Science Alert

Mouen-Bedimo, J. A.; Njiayouom, I.; Bieysse, D.; Ndoumbe-Nkeng, M.; Cilas, C.; Notteghem, J. L.

Coffee berry disease (CBD), caused by Colletotrichum kahawae, is a major constraint for Arabica coffee cultivation in Africa. The disease is specific to green berries and can lead to 60% harvest losses. In Cameroon, mixed cropping systems of coffee with other crops, such as fruit trees, are very widespread agricultural practices. Fruit trees are commonly planted at random on coffee farms, providing a heterogeneous shading pattern for coffee trees growing underneath. Based on a recent study of CBD, it is known that those plants can reduce disease incidence. To assess the specific effect of shade, in situ and in vitro disease development was compared between coffee trees shaded artificially by a net and trees located in full sunlight. In the field, assessments confirmed a reduction in CBD on trees grown under shade compared with those grown in full sunlight. Artificial inoculations in the laboratory showed that shade did not have any effect on the intrinsic susceptibility of coffee berries to CBD. Coffee shading mainly acts on environmental parameters in limiting disease incidence. In addition to reducing yield losses, agroforestry system may also be helpful in reducing chemical control of the disease and in diversifying coffee growers\' incomes.

Source : Phytopathology 2008 vol.98 (12), pp 1320 - 1325

Noonim, P.; Mahakarnchanakul, W.; Nielsen, K. F.; Frisvad, J. C.; Samson, R. A.

During 2006 and 2007, a total of 64 Thai dried coffee bean samples (Coffea arabica) from 2 growing sites in Chiangmai Province and 32 Thai dried coffee bean samples (Coffea canephora) from 2 growing sites in Chumporn Province, Thailand, were collected and assessed for fumonisin contamination by black aspergilli. No Fusarium species known to produce fumonisin were detected; however, black aspergilli had high incidences on both Arabica and Robusta Thai coffee beans. LC with high-resolution mass spectrometric (HRMS) detection showed that 67% of Aspergillus niger isolates from coffee beans were capable of producing fumonisins B2 (FB2) and B4 when grown on Czapek Yeast Agar with 5% NaCl. Small amounts (1-9.7 ng/g) of FB2 were detected in 7 of 12 selected coffee samples after ion-exchange purification and LC-MS/MS detection. 2 samples also contained FB4. This is the 1st record of freshly isolated A. niger strains producing fumonisins and the first report on the natural occurrence of FB2 and FB4 in coffee.

Source : Food Add Contam Part A Chemistry 2009 vol.26 (1), pp 94 - 100

Gil-Serna, J.; Gonzalez-Salgado, A.; Gonzalez-Jaen, M. A.; Vazquez, C.; Patino, B.

Aspergillus ochraceus and A. westerdijkiae are considered the most important Ochratoxin A (OTA) producing species included in Aspergillus section Circumdati which contaminate foodstuffs and beverages for human consumption. In this work a real-time quantitative PCR protocol was developed to detect both species using SYBR Green and primers designed on the basis of the multicopy ITS1 region of the rDNA. The assay had high efficiency (94%) and showed no inhibition by host or fungal DNA other than the target species. The lower detection limit of the target DNA was 2.5 pg/reaction. Accuracy of detection and quantification by qPCR were tested with genomic DNA obtained from green coffee beans and grapes artificially contaminated with spore suspensions of known concentrations. Spore concentrations equal or higher than 10(6) spore/ml could be detected by the assay directly without prior incubation of the samples and a positive relationship was observed between incubation time and qPCR values. The assay developed would allow rapid, specific, accurate and sensitive detection and quantification of A. ochraceus and A. westerdijkiae to be directly used in a critical point of the food chain, before harvesting green coffee and grape berries, to predict and control fungal growth and OTA production.

Source : Int J Food Microbiol 2009 vol.131 (2-3), pp 162 - 167

Mendonca, J.-C. F.; Franca, A. S.; Oliveira, L. S.

The presence of defective coffee beans is known to depreciate the quality of coffee beverage consumed worldwide. These beans represent about 15-20% of the total coffee produced in Brazil and, although they are separated from the non-defective beans, they are still commercialized in the coffee trading market. Thus, it was the aim of this work to verify if physical characteristics provide an effective discrimination of defective and non-defective coffees of both Arabica and Robusta species, before and after roasting. The evaluated parameters were size (volume), density and color. The results obtained in the present study showed that, within a given coffee species, defective beans can be separated from non-defective ones by sieving, before roasting. In the case of Arabica coffees, size separation between non-defective and defective can also be accomplished after roasting. Prior to roasting, color separation will be effective for Robusta coffees, but ineffective for separation of non-defective, immature and light sour Arabica beans.

Source : J Food Eng 2009 vol.92 (4), pp 474 - 479

Narasimharao, Kondamudi; Mohapatra, S. K.; Mano, Misra

Production of energy from renewable and waste materials is an attractive alternative to the conventional agricultural feed stocks such as corn and soybeans. This paper describes an approach to extract oil from spent coffee grounds and to further transesterify the processed oil to convert it into biodiesel. This process yields 10-15% oil depending on the coffee species (Arabica or Robusta). The biodiesel derived from the coffee grounds (100% conversion of oil to biodiesel) was found to be stable for >1 month under ambient conditions. It is projected that 340 million gallons of biodiesel can be produced from the waste coffee grounds around the world. Coffee grounds after oil extraction are ideal materials for garden fertilizer, feedstock for ethanol, and as fuel pellets.

Source : J Agric Food Chem 2008 vol.56(24), pp11757 - 11760

Cua, W. L.; Pease-Campbell, J. A.; Stewart, J. T.

Suboptimal seizure duration is commonly encountered in electroconvulsive therapy practice, especially in older patients with higher seizure thresholds. Intravenous caffeine is commonly used to improve seizure duration and quality in such patients and is generally well tolerated aside from occasional reports of relatively benign ventricular ectopy. We describe a patient with no previous history of cardiac disease or arrhythmia who developed sustained bigeminy and 2 brief runs of ventricular tachycardia after caffeine administration. Although intravenous caffeine is generally well tolerated, the clinician should be aware of the potential for unpredictable and serious ventricular arrhythmias.

Suorce : J ECT 2009 vol.25 (1), pp 70 - 71

Riksen, N. P.; Rongen, G. A.; Smits, P.

Despite decades of research, the question as to whether coffee intake increases the risk of coronary heart disease (CHD) remains controversial. In the current paper, we discuss the acute and long-term cardiovascular effects of coffee, and its major constituents, which could underlie such an association. Experimental studies have shown that administration of coffee or caffeine acutely raises blood pressure, circulating concentrations of (nor)epinephrine, increases arterial stiffness, impairs endothelium dependent vasodilation and inhibits ischemic preconditioning. The adverse effects of chronic coffee consumption on traditional risk factors for CHD are less consistent: although coffee intake slightly increases blood pressure, and plasma concentrations of homocysteine and cholesterol, there is no association with the incidence of hypertension, and a strong negative association with the incidence of type 2 diabetes mellitus. Moreover, common polymorphisms in genes involved in the metabolism of caffeine, catecholamines, homocysteine, and cholesterol can modulate the effect of coffee intake on cardiovascular parameters. Many epidemiological studies have explored the association between coffee drinking and CHD. Most prospective studies have not shown a positive association, whereas case-control studies in general have reported such an association. This discrepancy could be explained by an acute adverse effect of coffee, rather than a long-term adverse effect. We postulate that coffee drinking may have an acute detrimental effect in triggering coronary events and increasing infarct size in selected patient groups, rather than promoting the development of atherosclerosis in the general population, and we propose an alternative approach to explore such an effect in epidemiological studies.

Source : Pharmacol Ther 2009 vol.121(2), pp 185 - 191

Spinetta, M. J.; Woodlee, M. T.; Feinberg, L. M.; Stroud, C.; Schallert, K.; Cormack, L. K.; Schallert, T.

Ethanol and caffeine are two of the most widely consumed drugs in the world, often used in the same setting. Animal models may help to understand the conditions under which incidental memories formed just before ethanol intoxication might be lost or become difficult to retrieve. OBJECTIVES: Ethanol-induced retrograde amnesia was investigated using a new odor-recognition test. MATERIALS AND METHODS: Rats thoroughly explored a wood bead taken from the cage of another rat, and habituated to this novel odor (N1) over three trials. Immediately following habituation, rats received saline, 25 mg/kg pentylenetetrazol (a seizure-producing agent known to cause retrograde amnesia) to validate the test, 1.0 g/kg ethanol, or 3.0 g/kg ethanol. The next day, they were presented again with N1 and also a bead from a new rat\'s cage (N2). RESULTS: Rats receiving saline or the lower dose of ethanol showed overnight memory for N1, indicated by preferential exploration of N2 over N1. Rats receiving pentylenetetrazol or the higher dose of ethanol appeared not to remember N1, in that they showed equal exploration of N1 and N2. Caffeine (5 mg/kg), delivered either 1 h after the higher dose of ethanol or 20 min prior to habituation to N1, negated ethanol-induced impairment of memory for N1. A combination of a phosphodiesterase-5 inhibitor and an adenosine A(2A) antagonist, mimicking two major mechanisms of action of caffeine, likewise prevented the memory impairment, though either drug alone had no such effect. Binge alcohol can induce retrograde, caffeine-reversible disruption of social odor memory storage or recall.

Source : Psychopharmacology (Berl) 2008 vol.201 (3), pp 361-371

Childs, E.; Hohoff, C.; Deckert, J.; Xu, K.; Badner, J.; de Wit, H.

Caffeine produces mild psychostimulant and sometimes anxiogenic effects by antagonizing adenosine at A(1) and A(2A) receptors, and perhaps through interactions with other transmitter systems. Adenosine receptors are colocalized and functionally interact with dopamine receptors in the brain. Thus, functional polymorphisms in the genes for either adenosine or dopamine receptors may affect responses to caffeine. In this study, we examined associations between self-reported anxiogenic effects of caffeine and variation in the genes for A(2A) (ADORA2A) and DRD(2) (DRD2) receptors. Healthy male and female individuals (n=102), who consumed less than 300 mg caffeine per week, ingested capsules containing 0, 50, 150, and 450 mg caffeine under double-blind conditions in four separate experimental sessions. Subjective anxiety was measured before and at repeated times after capsules were consumed. At the 150 mg dose of caffeine, we found a significant association between caffeine-induced anxiety (Visual Analog Scales, VAS) and ADORA2A rs5751876 (1976C/T), rs2298383 (intron 1a) and rs4822492 (3\'-flank), and DRD2 rs1110976 (intron 6). Caffeine-induced anxiety (VAS) was also associated with two-loci interactions of selected ADORA2A and DRD2 polymorphisms. The lowest dose of caffeine did not increase ratings of anxiety while the highest dose increased anxiety in the majority of subjects. These findings provide support for an association between an ADORA2A polymorphism and self-reported anxiety after a moderate dose of caffeine. It is likely that other ADORA2A and DRD2 polymorphisms also contribute to responses to caffeine.

Source :  Neuropsychopharmacology 2008 vol.33 (12), pp 2791 - 2800

Ramalakshmi, K.; Rao, L.-J. M.; Takano-Ishikawa, Y.; Goto, M.

Methanolic extracts of low-grade green coffee beans (LCB) and spent coffee were analysed for radical-scavenging activity (alpha,alpha-diphenyl-beta-picrylhydrazyl radical) and oxygen radical absorbance capacity (ORAC). The extracts were also evaluated for anti-tumour (P388 cell assay), anti-inflammatory (J774A.1 cell assay) and anti-allergenic (RBL-2H3 cell line) activities in vitro. LCB extract was found to exhibit a radical-scavenging activity of 92.0% followed by spent Arabica (86.9%) and spent Robusta (82.0%) at a concentration of 50 ppm. The antioxidant activity of LCB extract, measured as Trolox equivalents (4416muM/g) was significantly (P < 0.05) higher than that of the spent coffee extracts. However, extracts of spent coffee exhibited significantly (P < 0.05) more anti-tumour activity than the LCB extract in terms of cell viability. This could be due to the possible role of brown pigments (melanoidins and phenolic polymers), formed during roasting, which may protect cells from oxidative damage in the biological system. However, both the extracts of LCB and spent coffee showed limited anti-inflammatory and anti-allergic activities. The presence of phenolics and chlorogenic acids in appreciable quantities along with brown pigments makes these coffee by-products a source for natural antioxidants.

Source : Food Chem 2009 vol.115 (1), pp 79 - 85

Wai-S-Tse; Chi-Choi-S-Chan; Shun-Yan, K. Shiu; Pik-Yee, A. Chung

Caffeinated drinks are commonly consumed in social gatherings. However, their effects on social behaviour remain unclear. The present study examined the effects of caffeinated coffee on antidepressant-related co-operative behaviour. 77 low-caffeine users took part in a randomized, double-blind, cross-over study of single dose of caffeinated coffee (150 mg caffeine) and decaffeinated coffee (9 mg caffeine) with at least a 3-day washout period. In each session, participants were asked to imagine a fictitious person and play the Mixed Motive Game with that person 45 min after coffee consumption. Heart rate, blood pressure and state moods were measured at baseline and at 45 min post-coffee consumption. After caffeinated coffee, participants exhibited significantly higher blood pressure. They also allocated significantly fewer scores to themselves and sent significantly more sadness message during the game. These results suggest that caffeinated coffee may help to improve social support and depressive symptoms.

Source : Nutritional Neuroscience 2009 vol.12 (1), pp 21 - 27

Kordosky-Herrera, K.; Grow, W. A.

As motor neurons approach skeletal muscle during development, agrin is released and induces acetylcholine receptor (AChR) clustering. Our laboratory investigates the effect of environmental agents on skeletal muscle development by using C2C12 cell culture. For the current project, we investigated both short-term and long-term exposure to caffeine, nicotine, or both, at physiologically relevant concentrations. Short-term exposure was limited to the last 48 h of myotube formation, whereas a long-term exposure of 2 weeks allowed for several generations of myoblast proliferation followed by myotube formation. Both agrin-induced and spontaneous AChR clustering frequencies were assessed. For agrin-induced AChR clustering, agrin was added for the last 16 h of myotube formation. Caffeine, nicotine, or
both significantly decreased agrin-induced AChR clustering during short-term and long-term exposure. Furthermore, caffeine, nicotine, or both significantly decreased spontaneous AChR clustering during long-term, but not short-term exposure. Surprisingly, caffeine and nicotine in combination did not decrease AChR clustering beyond the effect of either treatment alone. We conclude that physiologically relevant concentrations of caffeine or nicotine decrease AChR clustering. Moreover, we predict that fetuses exposed to caffeine or nicotine may be less likely to form appropriate neuromuscular synapses.

Source : Cell Tissue Res 2009 vol.335 (2), pp 341 - 348  

Masdrakis, V. G.; Markianos, M.; Vaidakis, N.; Papakostas, Y. G.; Oulis, P.

Breath-holding (BH) has been used as a simple probe to increase endogenous carbon dioxide (CO2). In patients with Panic Disorder (PD), lower baseline BH duration is associated with caffeine-induced panic attacks. In this paper, we assessed BH duration in PD patients in relation to panic attacks induced by caffeine intake. METHODS: BH duration and state anxiety were assessed in 40 PD patients (12 males), both at baseline and after a 400-mg caffeine challenge test. RESULTS: Patients panicking after caffeine administration (14 patients, 4 males) exhibited a significant reduction of their post-challenge BH duration, while no change of the BH duration was observed in non-panicking patients (26 patients, 8 males). Reduction in post-challenge BH duration was not related to higher anxiety levels--as reflected in the State-Trait Anxiety Inventory-State Form scores--independently of the occurrence of a panic attack. Panickers exhibited significantly lower baseline BH duration, compared to non-panickers.

CONCLUSIONS: Our findings indicate that in PD patients, caffeine-induced panic attacks are strongly associated with a significant reduction of BH duration at both pre- and post-challenge. Jointly, these findings suggest that in a subgroup of PD patients, sensitivity to endogenous CO2 accumulation may underlie both the lower BH durations and the caffeine-induced panic attacks. In this subgroup of PD patients, caffeine might exert its panicogenic properties through the exacerbation of patients\' already pathological hypersensitivity to CO2 accumulation, as indicated by both the significant decrease of their BH duration at post-challenge and by their significantly lower baseline BH duration respectively.

Source : Prog Neuropsychopharmacol Biol Psychiatry 2009 vol.33 (1), pp 41 - 44

Charles, B. G.; Townsend, S. R.; Steer, P. A.; Flenady, V. J.; Gray, P. H.; Shearman, A.

The objective of this study was to develop a population model of the pharmacokinetics (PK) of caffeine after orogastric or intravenous administration to extremely premature neonates with apnea of prematurity who were to undergo extubation from ventilation. Infants of gestational age <30 weeks were randomly allocated to receive maintenance caffeine citrate dosing of either 5 or 20 mg/kg/d. Four blood samples were drawn at prerandomized times from each infant during caffeine treatment. Serum caffeine was assayed by enzyme-multiplied immunoassay technique. Concentration data (431 samples, median: 4 per subject) were obtained from 110 (52 male) infants of mean birth weight of 1009 g, current mean weight (WT) of 992 g, mean gestational age of 27.6 weeks, and mean postnatal age (PNA) of 12 days. Of 1022 doses given, 145 were orogastric, permitting estimation of absolute bioavailability. A 1-compartment model with first-order absorption was fitted to the data in NONMEM. Patient characteristics were screened (P < 0.01) in nested models for pharmacokinetic influence. Model stability was assessed by nonparametric bootstrapping. Clearance (CL) increased nonlinearly with increasing PNA, whereas volume of distribution (Vd) increased linearly with WT, according to the following allometric models: CL (L/h) = 0.167 (WT/70) (PNA/12); Vd (L) = 58.7 (WT/70). The mean elimination half-life was 101. Interindividual variability (IIV) of CL and Vd was 18.8 % and 22.3 %, respectively. Interoccasion variability (IOV) of CL and Vd was 35.1% and 11.1%, respectively. This study established that the elimination of caffeine was severely depressed in extremely premature infants but increased nonlinearly after birth up to age 6 weeks. Caffeine was completely absorbed, which has favorable implications for switching between intravenous and orogastric routes. The interoccasion variability about CL was twice the interindividual variability, which, among other factors, indicates that routine serum concentration monitoring of caffeine in these patients is not warranted.

Source : Ther Drug Monit 2008 vol.30 (6), pp 709 - 716

Rossi, S.; De Chiara, V.; Musella, A.; Mataluni, G.; Sacchetti, L.; Siracusano, A.; Bernardi, G.; Usiello, A.;
Centonze, D.

Caffeine, the psychoactive ingredient of coffee and of many soft drinks, is frequently abused by humans especially during stressful live events. The endocannabinoid system is involved in the central effects of many psychoactive compounds and of stress. Whether caffeine alters the cannabinoid system and interferes with stress-induced synaptic alterations is however unknown. We have studied electrophysiologically the sensitivity of cannabinoid receptors modulating synaptic transmission in the striatum of mice exposed to caffeine in their drinking solution. Chronic caffeine assumption sensitized GABAergic synapses to the presynaptic effect of cannabinoid CB1 receptor stimulation by exo- and endocannabinoids. Caffeine was conversely unable to affect the sensitivity of cannabinoid receptors modulating glutamate transmission. The synaptic effects of caffeine were slowly reversible after its removal from the drinking solution. Furthermore, although exposure to caffeine for only 24h did not produce measurable changes of the sensitivity of cannabinoid CB1 receptors, it was able to contrast the down-regulation of CB1 receptor-mediated responses after social defeat stress. Our data suggest that the cannabinoid system is implicated in the psychoactive properties of caffeine and in the ability of caffeine to reduce the pathological consequences of stress.

Source : Neuropharmacology 2009 vol.56 (3), pp 590 - 597

Hume, J. R.; McAllister, C. E.; Wilson, S. M.

Caffeine is a well described and characterized ryanodine receptor (RyR) activator. Previous evidence from independent research studies also indicate caffeine inhibits InsP3 receptor functionality, which is important to activation of capacitative Ca2+ entry (CCE) in some cell types. In addition, RyR activation elicits excitatory-coupled Ca2+ entry (ECCE) in skeletal muscle myotubes. Recent studies by our group show that canine pulmonary arterial smooth muscle cells (PASMCs) have functional InsP3 receptors as well as RyRs, and that CCE is dependent on InsP3 receptor activity. The potential for caffeine to activate ECCE as well as inhibit InsP3 receptor function and CCE was examined using fura-2 fluorescent imaging in canine PASMCs. The data show caffeine causes transient as well as sustained cytosolic Ca2+ increases, though this is not due to CCE or ECCE activity as evidenced by a lack of an increase in Mn2+ quench of fura-2. The experiments also show caffeine reversibly inhibits 5-HT elicited-InsP3 mediated Ca2+ responses with an IC50 of 6.87x10(-4) M and 10 mM caffeine fully inhibits CCE. These studies provide the first evidence that caffeine is an inhibitor of InsP3 generated Ca2+ signals and CCE in PASMCs.

Source : Vascul Pharmacol 2009 vol.50 (3-4), pp 89 - 97

Chavez-Valdez, R.; Wills-Karp, M.; Ahlawat, R.; Cristofalo, E. A.; Nathan, A.; Gauda, E. B.

Caffeine, a nonspecific adenosine receptor (AR) antagonist is widely used to treat apnea of prematurity. Because adenosine modulates multiple biologic processes including inflammation, we hypothesized that AR blockade by caffeine would increase cytokine release from neonatal monocytes. Using cord blood monocytes (CBM), we investigated 1) the changes in AR mRNA profile by real time quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) and protein expression (western blot) after in vitro culture, caffeine or lipopolysaccharide (LPS) exposure, and 2) the modulation of cytokine release and cyclic adenosine monophosphate (cAMP) production by enzyme-linked immunosorbent assay (ELISA) induced by caffeine and specific AR antagonists: DPCPX(A1R), ZM241385(A2aR), MRS1754(A2bR), and MRS1220(A3R). After 48 h in culture, A2aR and A2bR gene expression increased 1.9 (p = 0.04) and 2.5¬fold (p = 0.003), respectively. A1R protein expression directly correlated with increasing LPS concentrations (p = 0.01), with minimal expression preexposure. Only caffeine (50 microM) and DPCPX (10 nM) decreased tumor necrosis factor-alpha (TNF-alpha) release from LPS activated-CBM by 20 and 25% (p = 0.01) and TNF-alpha gene expression by 30 and 50%, respectively, in conjunction with a > or
=2-fold increase in cAMP (p < 0.05). AR blockade did not modulate other measured cytokines. The induction of A1R after LPS exposure suggests an important role of this receptor in the control of inflammation in neonates. Our findings also suggest that caffeine, via A1R blockade, increases cAMP production and inhibits pretranscriptional TNF-alpha production by CBM.

Source :  Pediatr Res  2009 vol.65 (2), pp 203 - 208

Smith, A. P.

Most studies of the effects of caffeine on performance have been conducted in the laboratory and further information is required on the real-life effects of caffeine consumption on cognition. In addition, possible effects of caffeine consumption on a range of health outcomes should also be assessed in these studies to enable cost-benefit analyses to be conducted. OBJECTIVES: Secondary analyses of a large epidemiological database (N = 3223 non-working participants, 57% female, with a mean age of 49.6 years, range 17-92 years) were conducted to examine associations between caffeine consumption (mean caffeine consumption was 140 mg/day, range 0-1800 mg) and cognitive failures (errors of memory, attention and action) in a non-working sample. Associations between caffeine consumption and physical and mental health problems were also examined. METHODS: The study involved secondary analyses of a database formed by combining the Bristol Stress and Health at Work and Cardiff Health and Safety at Work studies. Associations between caffeine consumption and frequency of cognitive failures and health outcomes were examined in a sample of non-workers. RESULTS: After controlling for possible confounding factors significant associations between caffeine consumption and fewer cognitive failures were observed. Initial analyses suggested that many health variables were associated with regular level of caffeine consumption. However, most of the significant effects of caffeine disappeared when demographic and lifestyle factors were controlled for. Consumption of caffeine was, however, associated with a reduced risk of depression. These effects were also observed in separate analyses examining the source of the caffeine (coffee and tea).

CONCLUSIONS: Overall, the results show that caffeine consumption may benefit cognitive functioning in a non-working population. This confirms earlier findings from working samples. This beneficial effect of caffeine was not associated with negative health consequences. Indeed, consumption of caffeine was found to be associated with a reduced risk of depression.

Source : Hum Psychopharmacol 2009 vol.24 (1), pp 29 - 34

Chen, Y.; Parrish, T. B.

The blood-oxygenation-level-dependent (BOLD) signal is dependent on multiple physiological factors such as cerebral blood flow (CBF), local oxygen metabolism (CMRO(2)) and cerebral blood volume (CBV). Since caffeine affects both CBF and neural activity, its effects on BOLD remain controversial. The calibrated BOLD approach is an excellent tool to study caffeine because it combines CBF and BOLD measures to estimate changes in CMRO(2). The present study used the calibrated BOLD approach with 5% CO(2) to determine if a 2.5 mg/kg intravenous injection of caffeine changes the coupling between CBF and CMRO(2) during motor and visual tasks. The results show that caffeine decreases n, the CBF:CMRO(2) coupling ratio, from 2.58 to 2.33 in motor (p=0.006) and from 2.45 to 2.23 in visual (p=0.002) areas respectively. The current study also demonstrated that caffeine does not alter cerebrovascular reactivity to CO(2). These results highlight the importance of the calibrated BOLD approach in improving interpretation of the BOLD signal in the presence of substances like caffeine.

Source : Neuroimage 2009 vol.44 (3), pp 647 - 652

Reichardt, N.; Gniechwitz, D.; Steinhart, H.; Bunzel, M.; Blaut, M.

Different high mol. wt. (HMW) coffee fractions were prepared by ultrafiltration of coffee brews obtained from beans subjected to light, medium or dark roasting and in vitro fermentability of the different fractions by human intestinal microflora was examined. Total carbohydrate concn. in coffee fractions ranged from 28.6 to 56.7 g/100 g, with galactomannans and arabinogalactans the predominant polysaccharides. Coffee polysaccharides were extensively fermented by intestinal bacteria, leading to production of short chain fatty acids. Butyrate was produced in slightly higher molar proportions from light roasted coffee fractions than from medium and dark roasted fractions. Production of high amounts of acetate and propionate indicated preferential stimulation of Bacteroides-Prevotella group bacteria by coffee polysaccharides. Antioxidative activity of the different coffee fractions was still apparent after 24 h of in vitro fermentation.

Source : Mol Nutr Food Res 2009 vol. 53(2), pp 287 - 299

Mukamal, K. J.; Hallqvist, J.; Hammar, N.; Ljung, R.; Gemes, K.; Ahlbom, A.; Ahnve, S.; Janszky, I.

Cohort studies have suggested little effect of coffee consumption on risk of acute myocardial infarction. The effect of coffee consumption on prognosis after myocardial infarction is uncertain. METHODS: In a population-based inception cohort study, we followed 1,369 patients hospitalized with a confirmed first acute myocardial infarction between 1992 and 1994 in Stockholm County, Sweden, as part of the Stockholm Heart Epidemiology Program. Participants reported usual coffee consumption over the preceding year with a standardized questionnaire distributed during hospitalization and underwent a health examination 3 months after discharge. Participants were followed for hospitalizations and mortality with national registers through November 2001. RESULTS: A total of 289 patients died during follow-up. Compared with intake of <1 cup per day, coffee consumption was inversely associated with mortality, with multivariable-adjusted hazard ratios of 0.68 (95% confidence interval [CI] 0.45-1.02) for 1 to <3 cups, 0.56 (95% CI 0.37-0.85) for 3 to <5 cups, 0.52 (95% CI 0.34-0.83) for 5 to <7 cups, and 0.58 (95% CI 0.34-0.98) for > or =7 cups per day (P trend .06). Coffee intake was not associated with hospitalization for congestive heart failure or stroke. Candidate lipid and inflammatory biomarkers did not appear to account for the observed inverse association with mortality.

CONCLUSIONS: Self-reported coffee consumption at the time of hospitalization for myocardial infarction was inversely associated with subsequent postinfarction mortality in this population with broad coffee intake. If confirmed in other settings, identification of relevant mechanisms could lead to an improved prognosis for survivors of acute myocardial infarction.

Source : Am Heart J 2009 vol.157 (3), pp 495 - 501

Zhang, W. L.; Lopez-Garcia, E.; Li, T. Y.; Hu, F. B.; van Dam, R. M.

Coffee has been linked to both beneficial and harmful health effects, but data on its relationship with cardiovascular disease and mortality in patients with type 2 diabetes are sparse. METHODS: This was a prospective cohort study including 7,170 women with diagnosed type 2 diabetes but free of cardiovascular disease or cancer at baseline. Coffee consumption was assessed in 1980 and then every 2-4 years using validated questionnaires. A total of 658 incident cardiovascular events (434 coronary heart disease and 224 stroke) and 734 deaths from all causes were documented between 1980 and 2004. RESULTS: After adjustment for age, smoking and other cardiovascular risk factors, the relative risks were 0.76 (95% CI 0.50-1.14) for cardiovascular diseases (p trend = 0.09) and 0.80 (95% CI 0.55¬1.14) for all-cause mortality (p trend = 0.05) for the consumption of >or=4 cups/day of caffeinated coffee compared with non-drinkers. Similarly, multivariable RRs were 0.96 (95% CI 0.66-1.38) for cardiovascular diseases (p trend = 0.84) and 0.76 (95% CI 0.54-1.07) for all-cause mortality (p trend = 0.08) for the consumption of >or=2 cups/day of decaffeinated coffee compared with non-drinkers. Higher decaffeinated coffee consumption was associated with lower concentrations of HbA(1c) (6.2% for >or=2 cups/day versus 6.7% for <1 cup/month; p trend = 0.02).

CONCLUSIONS: These data provide evidence that habitual coffee consumption is not associated with increased risk of cardiovascular diseases or premature mortality among diabetic women.

Source : Diabetologia 2009 vol.52 (5), pp 810 - 817

Lopez-Garcia, E.; Rodriguez-Artalejo, F.; Rexrode, K. M.; Logroscino, G.; Hu, F. B.; van Dam, R. M.

Data on the association between coffee consumption and risk of stroke are sparse. We assessed the association between coffee consumption and the risk of stroke over 24 years of follow-up in women. METHODS AND RESULTS: We analyzed data from a prospective cohort of 83,076 women in the Nurses\' Health Study without history of stroke, coronary heart disease, diabetes, or cancer at baseline. Coffee consumption was assessed first in 1980 and then repeatedly every 2 to 4 years, with follow-up through 2004. We documented 2280 strokes, of which 426 were hemorrhagic, 1224 were ischemic, and 630 were undetermined. In multivariable Cox regression models with adjustment for age, smoking status, body mass index, physical activity, alcohol intake, menopausal status, hormone replacement therapy, aspirin use, and dietary factors, the relative risks (RRs) of stroke across categories of coffee consumption (<1 cup per month, 1 per month to 4 per week, 5 to 7 per week, 2 to 3 per day, and >or=4 per day) were 1, 0.98 (95% CI, 0.84 to 1.15), 0.88 (95% CI, 0.77 to 1.02), 0.81 (95% CI, 0.70 to 0.95), and 0.80 (95% CI, 0.64 to 0.98) (P for trend=0.003). After further adjustment for high blood pressure, hypercholesterolemia, and type 2 diabetes, the inverse association remained significant. The association was stronger among never and past smokers (RR for >or=4 cups a day versus <1 cup a month, 0.57; 95% CI, 0.39 to 0.84) than among current smokers (RR for >or=4 cups a day versus <1 cup a month, 0.97; 95% CI, 0.63 to 1.48). Other drinks containing caffeine such as tea and caffeinated soft drinks were not associated with stroke. Decaffeinated coffee was associated with a trend toward lower risk of stroke after adjustment for caffeinated coffee consumption (RR for >or=2 cups a day versus <1 cup a month, 0.89; 95% CI, 0.73 to 1.08; P for trend=0.05).

CONCLUSIONS: Long-term coffee consumption was not associated with an increased risk of stroke in women. In contrast, our data suggest that coffee consumption may modestly reduce risk of stroke.

Source : Circulation 2009 vol.119 (8), pp 1116 - 1123

Nkondjock, A.

Habitual coffee drinking has been associated with a reduced risk of mortality and chronic diseases, including cancer. The favourable influence of coffee is supported by several plausible mechanisms due to the presence of a variety of biological compounds such as caffeine, diterpenes, caffeic acid, polyphenols as well as volatile aroma and heterocyclic substances. Current evidence suggests that coffee consumption is associated with a reduced risk of liver, kidney, and to a lesser extent, premenopausal breast and colorectal cancers, while it is unrelated to prostate, pancreas and ovary cancers. Coffee drinking may still help reduce death due to liver cancer.

Source : Cancer Lett vol.277 (2), pp 121 - 125

Driessen, M. T.; Koppes, L. L.; Veldhuis, L.; Samoocha, D.; Twisk, J. W.

Coffee consumption has been postulated to decrease the risk of diabetes mellitus type II. The long-term effects of coffee consumption on the metabolic syndrome (MS) and its components are unknown. This study investigated the relationship of long-term coffee consumption between the age of 27 and 36 years with the prevalence of the MS at the age of 36 years. SUBJECT/METHODS: Data on coffee consumption and the MS components were derived from a healthy sample of 174 men and 194 women followed up from the age of 27 years onwards. Data analysis was performed with the use of generalized estimating equations and regression analysis. RESULTS: At the age of 36 years, the prevalence of the MS was 10.1%. The growth of coffee consumption did not differ significantly between subjects with or without the MS or its components. Regression analyses showed that one cup day(-1) higher coffee consumption was related to 0.11 mm Hg lower mean arterial blood pressure (P=0.03), 0.02 mg 100 ml(-1) higher triglyceride level (P=0.57), 0.04 mg 100 ml(-1) higher high-density lipoprotein cholesterol level (P=0.35), 0.09% higher HbA(1c) (P=0.12) and 0.02 cm larger waist circumference (P=0.57). After adjustment for physical activity, energy intake, smoking behaviour and alcohol consumption, none of the relationships between coffee consumption and the MS or its components was significant.

CONCLUSIONS: Coffee consumption is not associated with the MS or its components in a healthy sample followed up for 9 years.

Source : Eur J Clin Nutr 2009 vol.63 (4), pp 536 - 542

Bravi, F.; Scotti, L.; Bosetti, C.; Gallus, S.; Negri, E.; La Vecchia, C.; Tavani, A.

We conducted a metaanalysis of published studies on the relation between coffee drinking and endometrial cancer risk, which included 2 cohort (201 cases) and 7 case-control studies (2409 cases). The summary relative risk (RR) for coffee drinkers vs nondrinkers was 0.80 (95% confidence interval [CI], 0.68-0.94), with significant heterogeneity between studies. Compared with nondrinkers, the summary RR was 0.87 (95% CI, 0.78-0.97) for low-to-moderate coffee drinkers and 0.64 (95% CI, 0.48-0.86) for heavy coffee drinkers. The summary RR for an increase of 1 cup/d was 0.93 (95% CI, 0.89-0.97), which suggests an inverse relation between coffee and endometrial cancer. However, the causality must be confirmed.

Source : Am J Obstet Gynecol 2009 vol.200 (2), pp 130 - 135

Facheris, M. F.; Schneider, N. K.; Lesnick, T. G.; de Andrade, M.; Cunningham, J. M.; Rocca, W. A.; Maraganore, D. M.

An inverse association between coffee and Parkinson\'s disease (PD) has been reported. However, it remains uncertain why some but not all coffee drinkers are less susceptible to PD. We considered the possibility of a pharmacogenetic effect. In our study, we included 1,208 subjects (446 case-unaffected sibling pairs and 158 case-unrelated control pairs) recruited from an ongoing study of the molecular epidemiology of PD in the Upper Midwest (USA). We collected information on lifetime coffee drinking and we studied two genes: ADORA2A, which encodes the major receptor activity of caffeine in the brain (variants rs5751876 and rs3032740), and CYP1A2, which encodes the major rate-limiting step of caffeine metabolism (variants rs35694136 and rs762551). We did not observe significant associations of coffee drinking or of the genetic variants with PD susceptibility, either independently or jointly, in the sample overall and in most strata. Our study neither supports the hypothesis that coffee protects against PD nor provides evidence for a pharmacogenetic effect.

Source : Mov Disord 2008 vol.23 (14), pp 2033 - 2040

Tunnicliffe, J. M.; Shearer, J.

Epidemiological studies show coffee consumption to be correlated to large risk reductions in the prevalence of type 2 diabetes (T2D). Such correlations are seen with decaffeinated and caffeinated coffee, and occur regardless of gender, method of brewing, or geography. They also exist despite clear evidence showing that caffeine causes acute postprandial hyperglycemia and lower whole-body insulin sensitivity. As the beneficial effects of coffee consumption exist for both decaffeinated and caffeinated coffee, a component of coffee other than caffeine must be responsible. This review examines the specific coffee compounds responsible for coffee\'s effects on T2D, and their potential physiological mechanisms of action. Being plant-derived, coffee contains many beneficial compounds found in fruits and vegetables, including antioxidants. In fact, coffee is the largest source of dietary antioxidants in industrialized nations. When green coffee is roasted at high temperatures, Maillard reactions create a number of unique compounds. Roasting causes a portion of the antioxidant, chlorogenic acid, to be transformed into quinides, compounds known to alter blood glucose levels. Coffee consumption may also mediate levels of gut peptides (glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1), hormones intimately involved in the regulation of satiety and insulin secretion. Finally, coffee may have prebiotic-like properties, altering gut flora and ultimately digestion. In summary, it is evident that a better understanding of the role of coffee in the development and prevention of T2D has the potential to uncover novel therapeutic targets and nutraceutical formulations for the disease.

Source : Appl Physiol Nutr Metab 2008 vol.33 (6), pp 1290 - 1300

Tunnicliffe, J. M.; Erdman, K. A.; Reimer, R. A.; Lun, V.; Shearer, J.

Caffeine is a proven ergogenic aid, increasing athletic performance, endurance, and mental chronometry at doses as low as 1-3 mg.kg-1. As coffee is a readily available and commonly ingested form of caffeine, the two are often equated. However, coffee also contains hundreds of other biologically active compounds, many of which are metabolically distinct from caffeine. The purpose of this review was to examine the prevalence of coffee and (or) caffeine consumption among elite Canadian athletes, and to delineate the effects of coffee and caffeine on physical activity, weight maintenance, performance, and metabolism. A total of 270 self-reported 3-day food records were examined for caffeine intake from athletes registered with Canadian Sport Centres in 2005 and 2006. Athletes ranged in age from 16-45 years, and competed in 38 different sports. Results showed that 30% of athletes ingested >1 mg.kg-1.day-1 from a variety of sources. Average daily intake was 0.85 +/- 13 mg.kg-1. Caffeine intake was not correlated with any 1 sport; the 10 highest caffeine users were athletes from 9 different sports, including skill, endurance, and power sports. No differences were noted for average caffeine ingestion between summer and winter sports. High caffeine intakes corresponded to coffee ingestion, with the 25 highest individual intakes (193-895 mg.day-1) from coffee drinkers. In summary, it can be concluded that the majority of high-level Canadian athletes consume dietary caffeine primarily in the form of coffee. However, levels consumed are insufficient to elicit performance enhancement. Potential detrimental effects of caffeine consumption on exercise performance include gastric upset, withdrawal, sleep disturbance, and interactions with other dietary supplements.

Source : Appl Physiol Nutr Metab 2008 vol.33 (6), pp 1301 - 1310

Bjorklund, O.; Halldner-Henriksson, L.; Yang, J.; Eriksson, T. M.; Jacobson, M. A.; Dare, E.; Fredholm, B.B.

We have examined behavioral consequences of genetic deletion of the adenosine A3 receptors in mice. The open field behavior of A3 adenosine receptor knock-out (A3R KO) mice was investigated both under basal conditions and after stimulation with psychostimulants. Adolescent (21 day-old) and adult A3R KO males showed an increase in overall motor activity compared to wild type (WT) males, but the type of activity differed. The motor activity, especially rearing, was also higher in A3R KO compared to WT adult females. A3 receptors have a low affinity for caffeine and it was therefore surprising to find a decreased response to stimulation with either caffeine or amphetamine in A3R KO as compared to WT mice in males as well as females. Telemetry recordings also showed a significantly smaller increase in activity upon darkness in A3R KO. There were no compensatory changes in the mRNA expression of any other adenosine receptor subtypes (A1, A2A and A2B) or any changes in dopamine D1 and D2 receptor binding in A3R KO brains. Challenge with the developmental toxicant methylmercury (1 microM in drinking water) during pregnancy and lactation did not cause any behavioral alterations in adolescent and adult WT female offspring. In contrast, the A3R KO female offspring displayed changes in locomotion indicating an interaction between perinatal methylmercury and adenosine A3 receptors. In conclusion, despite low expression of A3 receptors in wild type mouse brain we observed several behavioral consequences of genetic elimination of the adenosine A3 receptors. The possibility that this is due to a role of A3 receptors in development is discussed.

Source : Physiol Behav 2008 vol.95 (5), pp 668 - 676

Terry, P.; Doumas, M.; Desai, R. I.; Wing, A. M.

The impacts of psychoactive drugs on timing have usefully informed theories of timing and its substrates. OBJECTIVES: The objectives of the study are to test the effects of alcohol and caffeine on the explicit timing involved in tapping with the implicit timing observed in the coordinated picking up of an object, and with the temporal discrimination. MATERIALS AND METHODS: Participants in the "alcohol" experiment (N = 16) received placebo, "low" (0.12 g/kg or 0.14 g/kg for women/men, respectively) or "high" (0.37 g/kg or 0.42 g/kg, respectively) doses of alcohol, and those in the "caffeine" experiment (N = 16) received placebo, 200 or 400 mg caffeine. Time production variability was measured by repetitive tapping of specified intervals, and sources of variance attributable to central timer processes and peripheral motor implementation were dissociated. The explicit timing in tapping was compared with the implicit timing in the coordinated picking up of an object. Time perception was measured as discrimination thresholds for intervals of similar duration. Drug effects on reaction time were also measured. RESULTS: For tapping, alcohol significantly increased timer variability, but not motor variability; it did not affect coordination timing in the grip-lift task. Conversely, for time perception, the low dose of alcohol improved temporal discrimination. Caffeine produced no effects on any of the timing tasks, despite significantly reducing reaction times.

CONCLUSIONS: The effects of alcohol argue against a common clock process underlying time interval perception and production in the range below 1 s. In contrast to reaction time measures, time perception and time production appear relatively insensitive to caffeine.

Source : Psychopharmacology (Berl) 2009 vol.202 (4), pp 719 - 729

Astorino, T. A.; Rohmann, R. L.; Firth, K.

Multiple studies corroborate the ergogenic properties of caffeine (CAF) for endurance performance, yet fewer investigations document the efficacy of acute caffeine intake for intense, short-term exercise. The aim of the study was to determine the ergogenic potential of caffeine during testing of muscular strength and endurance. Twenty-two resistance-trained men ingested CAF (6 mg/kg) or placebo (PL) 1 h pre-exercise in a randomized, double-blind crossover design. They refrained from caffeine intake and strenuous exercise 48 and 24 h, respectively, pre-visit. Initially, resting heart rate and blood pressure were obtained followed by one-repetition maximum (1-RM) testing on the barbell bench press and leg press. Upon determination of 1-RM, participants completed repetitions to failure at 60%1-RM. Heart rate, blood pressure, and rating of perceived exertion (RPE) were measured after the final repetition. Compared to PL, there was no effect (P > 0.05) of caffeine on muscular strength, as 1-RM bench press (116.4 +/- 23.6 kg vs. 114.9 +/- 22.8 kg) and leg press (410.6 +/- 92.4 kg vs. 394.8 +/- 95.4 kg) were similar. Total weight lifted during the 60% 1-RM trial was 11 and 12% higher for the bench press and leg press with caffeine compared to placebo, yet did not reach significance. RPE was similar at the end of resistance exercise with CAF vs. PL. Acute caffeine intake does not significantly alter muscular strength or endurance during intense bench press or leg press exercise, yet the practical importance of the increased muscular endurance remains to be explored.

Source : Eur J Appl Physiol 2008 vol.102 (2), pp 127 - 132

Carr, A.; Dawson, B.; Schneiker, K.; Goodman, C.; Lay, B.

This study examined the effects of 6 mgxkg(-1) caffeine ingestion in team-sport players (N.=10) on repeated-sprint running performance (5 sets of 6 x 20 m) and reaction times, 60 min after caffeine or placebo ingestion. METHODS: Best single sprint and total set sprint times, blood lactate and simple and choice reaction times (RT) were measured. RESULTS: Total sprint times across sets 1, 3 and 5 (departure every 25 s) were significantly faster after caffeine (85.49+/-5.55 s) than placebo (86.98+/-5.78 s) (P<0.05). Similarly, total sprint times across sets 2 and 4 (departure every 60 s), were significantly faster after caffeine (55.99+/-3.64 s) than placebo (56.77+/-3.74 s) (P<0.05). Significantly higher blood lactates were recorded in caffeine compared to placebo after set 3 (13.1+/-1.2 vs 10.3+/-1.4 mmolxL(-1)) (P<0.05) and set 5 (13.1+/-1.3 vs 10.3+/-1.6 mmolxL(-1)) (P<0.01). There were no significant effects on simple or choice RT, although effect sizes suggested improved post-exercise times after caffeine.

CONCLUSION: Caffeine ingestion 60 min prior to exercise can enhance repeated sprint running performance and is not detrimental to reaction times.

Source : J Sports Med Phys Fitness 2008 vol.48 (4), pp 472 - 478 (not available on line)

Carmen-Velazquez-Pereda, M.; Campos-Dieamant, G.; Eberlin, S.; Nogueira, C.; Colombi, D.; Di Stasi, L.C.; Souza-Queiroz, M. L.

Background Green Coffea arabica L. seed oil is being widely used in cosmetic formulations, although its effects on human skin cells are not clear and most observations are unpublished. Aims In this study, we evaluated the in vitro effects of green coffee (C. arabica L.) oil (GCO) on the synthesis of collagen, elastin,
and glycosaminoglycans (GAG) and in the release of transforming growth factor-beta1 (TGF-beta1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) by human skin fibroblasts. We also investigated the ability of GCO to increase aquaglycerolporins-3 (AQP-3) mRNA expression in cultured keratinocytes and human skin explants. Methods Human fibroblasts were incubated for 48 h with several GCO concentrations (3.12, 6.25, 12.5, 25.0 and 50.0 mg/mL). The levels of growth factors and extracellular matrix compounds in the culture supernatant were measured using commercial kits. To evaluate AQP-3 relative expression, using real-time reverse transcription polymerase chain reaction, keratinocytes were incubated for 3-6 h with the GCO optimal concentration of 25.0 mg/mL. Histological sections of human skin were also incubated with GCO (25.0 mg/mL) and immunostained by antiserum against AQP-3. Results Our results demonstrated that incubation with GCO produces a dose-dependent stimulation in the synthesis of collagen, elastin, and GAG, in addition to increasing the release of the growth factors TGF-beta1 and GM-CSF. GCO also induced the expression of AQP-3 mRNA, which reached levels up to 6.5-fold higher than those of the control cultures. Conclusion The findings presented herein suggest that GCO might improve physiological balance in the skin, thus allowing the formation of new connective tissue, and preventing epidermis dryness by increasing AQP-3 levels. Taking into account the limitations of in vitro studies, it is encouraging in this context to consider CGO as an adjuvant to be used in dermocosmetic formulations. Clinical studies are in progress in our laboratory aiming to further investigate the protective effects of CGO in the skin.

Source : J Cosmet Dermatol 2009 vol.8 (1), pp 56 - 62  (not available on line)

Smith, A.

Recent research has shown that even small doses (<40mg) of caffeine can improve alertness and increase performance efficiency on attention tasks. Previous studies have given the caffeine in a variety of beverages or in capsules and it was of interest to see whether similar effects could be observed when the caffeine was given in gum. In addition, chewing gum has been shown to have behavioural effects and the present study extended our knowledge of this topic. OBJECTIVES: To compare the effects of caffeinated gum (40 mg), placebo gum and no gum conditions on mood and attention. METHODS: A double blind placebo controlled study was conducted with volunteers being randomly assigned to one of the three conditions. Baseline measures of mood and attention were taken prior to chewing and a test session was then conducted. One hundred and eighteen young adults participated in the study. RESULTS: Caffeinated gum was associated with a more positive mood and better performance on tasks requiring sustained attention. The caffeine improved the speed of encoding of new information which is consistent with previous findings. Chewing placebo gum was also found to be associated with more positive mood, both shortly after chewing and at the end of the study. CONCLUSIONS: The implications of the present study are that chewing caffeinated gum has been shown to improve performance efficiency and mood by its alerting and energising effects. The profile of caffeine effects is what one would predict from the existing caffeine literature and such effects may be extremely beneficial in real-life situations. Prior chewing of placebo gum was associated with a more positive mood and this also confirms previous findings.

Source : Hum Psychopharmacol 2009 vol.24 (3), pp239 - 247

Justinova, Z.; Ferre, S.; Barnes, C.; Wertheim, C. E.; Pappas, L. A.; Goldberg, S. R.; Le Foll, B.

Adenosine receptors are involved in cocaine and methamphetamine discrimination and exposure to caffeine can affect behavioral effects of nicotine in rats. OBJECTIVES: Here we investigated the relative involvement of adenosine A(1) and A(2A) receptors in nicotine, cocaine, and methamphetamine discrimination, before and/or during chronic caffeine exposure. MATERIALS AND METHODS: The nonselective adenosine receptor antagonist caffeine, the A(1)-receptor antagonist cyclopentyltheophylline (CPT), and the A(2A)-receptor antagonist MSX-3 were evaluated in rats trained to discriminate 0.4 mg/kg nicotine from saline under a fixed-ratio schedule of food delivery. Effects of adenosine receptor antagonists were then compared in rats discriminating nicotine, methamphetamine, or cocaine from saline during chronic caffeine exposure in their drinking water. RESULTS: Caffeine, CPT, and MSX-3 partially generalized to nicotine and shifted nicotine dose-response curves leftwards. During chronic caffeine exposure, however, all three ligands failed to generalize to nicotine and failed to shift nicotine dose-response curves. In previous experiments, CPT and MSX-3 partially generalized to methamphetamine and cocaine and shifted dose-response curves leftwards. In the present experiments, CPT neither generalized nor shifted dose-response curves for methamphetamine or cocaine during chronic caffeine exposure. However, MSX-3 partially generalized to both psychostimulants and shifted their dose-response curves leftwards. Caffeine partially generalized to cocaine, but not methamphetamine, and shifted both dose-response curves leftwards. CONCLUSIONS: Both adenosine A(1) and A(2A) receptors are capable of modulating the discriminative-stimulus effects of nicotine. Chronic caffeine exposure produces complete tolerance to both A(1)- and A(2A)-mediated effects in nicotine-trained rats. In contrast, chronic caffeine exposure produces tolerance to adenosine A(1)-mediated, but not A(2A)-mediated, effects in methamphetamine- and cocaine-trained rats.

Source : Psychopharmacology (Berl) 2009 vol.203 (2), pp 355 - 367

Keane, M. A.; James, J. E.

Until recently, little account had been taken of the confounding effects of caffeine withdrawal and withdrawal reversal when examining the net effects of dietary caffeine. OBJECTIVES: By including a manipulation involving sleep restriction, the present study aimed to extend recent findings from research in which caffeine withdrawal and withdrawal reversal were controlled. The main aims of the study were to examine the net effects of caffeine, as well as its potential restorative effects following sleep restriction, on EEG, performance and mood. METHOD: A randomised cross-over design was used in which 15 participants alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for four consecutive weeks following either usual sleep or sleep restriction. EEG activity was measured at 32 sites during eyes closed, eyes open and performance of a vigilance task. RESULTS: Modest effects of caffeine were found in the delta and beta bandwidths, but no main effects of caffeine were observed in the theta or alpha bandwidths. Overall, the effects of caffeine on EEG activity were relatively few, weak and inconsistent, and no evidence was found of net restorative effects of caffeine for any outcome variables.

CONCLUSIONS: The findings do not support the use of caffeine as a means for enhancing human function or as an antidote to the negative effects of sleep loss.

Source : Hum Psychopharmacol 2008 vol.23 (8), pp 669 - 680

Silant\'eva, D. I.; Gainutdinova, T. K.; Andrianov, V. V.; Gainutdinov, KhL

Chronic administration of caffeine to common snails increased the rate of formation of a conditioned defensive reflex. When daily caffeine injections were given immediately after the training procedure, the conditioned defensive reflex was acquired more quickly than when caffeine injections were given before the training procedure started. Chronic caffeine administration to both trained and untrained snails led to depolarization changes in the membrane potential and reductions in the threshold potential of defensive behavior command neurons in common snails. Comparative studies showed that addition of caffeine to the solution bathing the mollusk nervous system resulted in decreases in the threshold potential of command neurons in both intact and trained snails; there was, however, no change in the membrane resting potential.

Source : Neurosci Behav Physiol 2009 vol.39 (4), pp 403 - 407

Bairam, A.; Montandon, G.; Joseph, V.; Lajeunesse, Y.; Kinkead, R.

Caffeine is a common treatment for apnea of prematurity. Although relatively safe, little is known about the potential long-term effects of this treatment on respiratory control development. We previously showed that adult male (but not female) rats previously subjected to neonatal caffeine treatment (NCT; 15mg/kg/day, postnatal days 3-12) show a higher breathing frequency response during the early phase of hypoxic exposure. To address the role of sexual hormones in this sexual dimorphism, the present study tested the hypothesis that in adult male rats, circulating testosterone contributes to NCT-related augmentation of the acute breathing frequency response to hypoxia. Whole body plethysmography was used to compare the acute ventilatory response to moderate hypoxia (FIO(2)=0.12; 20min) between rats previously subjected to NCT or neonatal water treatment (NWT; same treatment as NCT but using water). In each group, rats were either sham-operated or gonadectomized (GDX) 14 days prior to ventilatory measurements. In sham-operated rats, the increase in breathing frequency measured during the first 8min of hypoxia was greater in NCT rats versus NWT. The hypoxic ventilatory response measured at the end of the hypoxia was not affected by treatment, thus indicating that NCT mainly affected the peripheral component of the chemoreflex. Gonadectomy had no effect on NCT but augmented the frequency response of NWT rats to the same level of NCT, thus eliminating the between-group difference. NCT may interfere with the inhibitory effect of circulating testosterone on carotid body function. Although appealing, additional experiments are necessary to substantiate this interpretation.

Source : Respir Physiol Neurobiol 2009 vol.165 (2-3), pp 261 - 265

Monda, M.; Viggiano, A.; Vicidomini, C.; Viggiano, A.; lannaccone, T.; Tafuri, D.; Luca, B. de

Caffeine induces modifications of activity of the autonomic nervous system. This study analyzed the effect of a cup of espresso coffee on the heart rate variability (HRV) power spectral analysis, which is a method providing evaluation of the sympathetic and parasympathetic discharge. In young, healthy sedentary subjects (10 male, 10 female; aged 25-30 yr), the HRV-power spectrum was evaluated over a period of 150 min after the administration of espresso coffee (caffeine, 75 mg) or decaffeinated coffee (caffeine, <18 mg) in supine and seated positions. Absolute values of the spectrum were summed in low (LF) and high frequencies (HF). The LF and HF spectra were used to estimate the sympathetic and parasympathetic activity, respectively. In the supine position, coffee increased HF, while decaffeinated
coffee caused little modification of HF. In the seated position, HF was not modified by coffee or decaffeinated coffee. Coffee and decaffeinated coffee did not induce any modification of LF in either position. It is concluded that espresso coffee influences parasympathetic activity in the supine position.

Source : Nutritional Neuroscience 2009 vol.12 (1), pp 43 - 48  

Geleijnse, J. M.

This paper summarizes the current epidemiological evidence on coffee consumption in relation to blood pressure (BP) and risk of hypertension. Data from cross-sectional studies suggest an inverse linear or U-shaped association of habitual coffee use with BP in different populations. Prospective studies suggest a protective effect of high coffee intake (4 or more cups per day) against hypertension, mainly in women. Furthermore, the risk of hypertension may be lower in coffee abstainers. Randomized controlled trials, which are mostly of short duration (1-12 weeks), have shown that coffee intake around 5 cups per day causes a small elevation in BP (approximately 2/1 mmHg) when compared to abstinence or use of decaffeinated coffee. With regard to underlying biological mechanisms, most research has been devoted to BP-raising effects of caffeine. However, there are many other substances in coffee, such as polyphenols, soluble fibre and potassium, which could exert a beneficial effect in the cardiovascular
system. Although the precise nature of the relation between coffee and BP is still unclear, most evidence suggests that regular intake of caffeinated coffee does not increase the risk of hypertension.

Source : Vasc Health Risk Manag 2008 vol.4 (5), pp 963 - 970 Pub  (full text)

McCann, S. E.; Yeh, M.; Rodabaugh, K.; Moysich, K. B.

Several studies have investigated the associations between diet and endometrial cancer, but few have focused specifically on coffee and tea. In a hospital-based case-control study, we examined the associations between endometrial cancer risk and usual consumption of coffee, decaffeinated coffee, and black tea among 541 women with endometrial cancer and 541 women with an intact uterus but without a cancer diagnosis seen at Roswell Park Cancer Institute (Buffalo, New York) between 1982 and 1998. Daily frequency of consumption of coffee, decaffeinated coffee, and black tea in the few years prior to diagnosis in cases and questionnaire completion in controls was assessed with a self-administered epidemiologic questionnaire and categorized as none, 0.5 cups/d, 1-2 cups/d and >2 cups/d. Odds ratios (OR) and 95% confidence intervals (CI) for each category referent to nondrinkers were estimated with unconditional logistic regression adjusting for age, endometrial cancer risk factors and each beverage mutually adjusted for other beverages. Compared to nondrinkers, we observed a nonsignificant negative association with endometrial cancer risk among women who reported >2 cups/d regular coffee (OR 0.71, 95% CI 0.49-1.03), a significant inverse association with >2 cups/d black tea (OR 0.56, 95% CI 0.35-0.90) and a significant inverse association with >4 cups/d combined coffee and tea consumption (OR 0.47, 95%; CI 0.28-0.80). These findings suggest coffee and tea may be important in reducing endometrial cancer risk.

Source : Int J Cancer 2009 vol.124 (7), pp 1650 - 1653

Ivy, J. L.; Kammer, L.; Zhenping, Ding; Bei, Wang; Bernard, J. R.; Yi, Hung Liao; Jungyun, Hwang

Not all athletic competitions lend themselves to supplementation during the actual event, underscoring the importance of preexercise supplementation to extend endurance and improve exercise performance. Energy drinks are composed of ingredients that have been found to increase endurance and improve physical performance. The purpose of this study was to investigate the effects of a commercially available energy drink, ingested before exercise, on endurance performance. The study was a double-blind, randomized, crossover design. After a 12-h fast, 6 male and 6 female trained cyclists (mean age 27.3 ± 1.7 yr, mass 68.9 ± 3.2 kg, and VO2 54.9 ± 2.3 ml kg-1 min-1) consumed 500 ml of either flavored placebo or Red Bull energy drink (ED; 2.0 g taurine, 1.2 g glucuronolactone, 160 mg caffeine, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 mug vitamin B12) 40 min before a simulated cycling time trial. Performance was measured as time to complete a standardized amount of work equal to 1 h of cycling at 70% Wmax. Results indicated that performance improved with ED compared with placebo (3690 ± 64 s vs. 3874 ± 93 s, P < .01), but there was no difference in rating of perceived exertion between treatments. b-Endorphin levels increased during exercise, with the increase for ED approaching significance over placebo (P = 0.10). Substrate utilization, as measured by open-circuit spirometry, did not differ between treatments. It is concluded that consuming a commercially available ED before exercise can improve endurance performance and that this improvement might be in part the result of increased effort without a concomitant increase in perceived exertion.

Source : Intern J Sport Nutr Exer Metab 2009 vo/.19 (1), pp 61 - 78

Radzeviciene, L.; Ostrauskas, R.

The aim of the study was to determine the association between coffee consumption and the risk of type 2 diabetes mellitus. MATERIAL AND METHODS: A case-control study included 234 cases with newly confirmed diagnosis of type 2 diabetes mellitus and 468 controls who were free of the disease in 2001. Cases and controls were matched by gender and age (+/-5 years). Data on age, education level, occupation status, marital status, family history of diabetes, lifestyle (dietary habits, smoking habits, coffee consumption, alcohol consumption, physical activity), and stress were collected via a questionnaire. Variables were retained in models as confounders when their inclusion changed the value of the OR by more than 10% in any exposure category. Conditional logistic regression to compute the odds ratio (OR), 95% confidence interval (CI), and P for trend was used. RESULTS: After adjustment for possible confounders (family history of diabetes, body mass index, eating speed, morning exercise, cigarette smoking, years of education, and stress), a statistically significant relationship was observed between type 2 diabetes mellitus and coffee consumption. Individuals consuming four or more cups of coffee per day were at lower risk of 2 diabetes mellitus (OR=0.51; 95% CI, 0.27-0.97) compared to those who consumed one or less than one cup of coffee per day.

CONCLUSION: Habitual coffee consumption of four or more cups per day might be related to the lower risk of type 2 diabetes mellitus.

Source : Medicina (Kaunas.) 2009 vol.45 (1), pp 61 - 67

Miller, E. A.; Manning, S. E.; Rasmussen, S. A.; Reefhuis, J.; Honein, M. A.

Anorectal atresia is a congenital anomaly with mostly unknown risk factors. Studies have provided evidence of teratogenic effects of alcohol and tobacco, and animal studies have suggested that caffeine may potentiate their teratogenicity. However, it is unclear how these factors affect the risk of anorectal atresia. We analysed data from maternal telephone interviews in a multistate case-control study with 464 infants with anorectal atresia and 4940 infants with no major birth defects. We used unconditional logistic regression to determine the association of exposure to smoking, environmental tobacco smoke (ETS), alcohol or caffeine with anorectal atresia. Effect modification by caffeine intake was assessed on additive and multiplicative scales. There was no association with alcohol intake in this analysis. However, there was some evidence of an association between anorectal atresia and maternal exposure to tobacco smoke and caffeine. Compared with non-smokers not exposed to ETS, the crude odds ratio (OR) and 95% confidence interval [CI] for cigarette smoking was 1.2 [95% CI 1.0, 1.5]. The association with anorectal atresia for non-smokers exposed to ETS at home and work was OR = 2.3 [95% CI 1.2, 4.1]. Compared with the lowest level of caffeine intake (<10 mg/day), the association for the highest caffeine intake (> or =300 mg/day) was OR = 1.5 [95% CI 1.0, 2.2]. Results did not change after adjustment for covariates. This study found evidence of associations between anorectal atresia and caffeine intake, cigarette smoking and exposure to ETS. Because there are currently few additional data to support these results, further study is needed.

Source : Paediatr Perinat Epidemiol 2009 vol.23 (1), pp 9 - 17

Yang, J. N.; Bjorklund, O.; Lindstrom-Tornqvist, K.; Lindgren, E.; Eriksson, T. M.; Kahlstrom, J.; Chen, J. F.; Schwarzschild, M. A.; Tobler, I.; Fredholm, B. B.

Caffeine is believed to exert its stimulant effects by blocking A(2A) and A(1) adenosine receptors (A(2A)R and A(1)R). Although a genetic knockout of A(2A)R eliminates effects of caffeine, the phenotype of the knockout animal does not resemble that of caffeine treatment. In this study we explored the possibility that a mere reduction of the number of A(1)Rs and A(2A)Rs, achieved by deleting one of the two copies of the A(1)R and A(2A)R genes, would mimic some aspects of long-term caffeine ingestion. The A(1)R and A(2A)R double heterozygous (A(1)R-A(2A)R dHz) mice indeed had approximately one-half the number of A(1)R and A(2A)R, and there were little compensatory changes in A(2B) or A(3) adenosine receptor (A(2B)R or A(3)R) expression. The ability of a stable adenosine analog to activate receptors was shifted to the right by caffeine and in A(1)R-A(2A)R dHz tissue. Caffeine (0.3 g/l in drinking water for 7-10 days) and A(1)R-A(2A)R dHz genotype increased locomotor activity (LA) and decreased heart rate without significantly influencing body temperature. The acute stimulatory effect of a single injection of caffeine was reduced in A(1)R-A(2A)R dHz mice and in mice treated long term with oral caffeine. Thus at least some aspects of long-term caffeine use can be mimicked by genetic manipulation of the A(1)R and A(2A)R.

Source : J Appl Physiol 2009 vol.106 (2), pp 631 - 639

Kastorini, C. M.; Chrysohoou, C.; Panagiotakos, D.; Aggelopoulos, P.; Liontou, C.; Pitsavos, C.; Stefanadis, C.

The aim of the present work was to evaluate the association between coffee consumption and the development of left ventricular systolic dysfunction (LVSD) in patients who had had an acute coronary syndrome. During 2006-2007, 144 male (65 +/- 14 years) and 50 female (71 +/- 12 years) post-acute coronary syndrome patients who developed LVSD (ejection fraction <40%) after the cardiac event and 129 male (64 +/- 12 years) and 51 female (67 +/- 10 years) post-acute coronary syndrome patients without LVSD (ejection fraction >50%) were included in the study. Participants were consequently selected. Detailed information regarding their medical records, sociodemographic and anthropometric data, and various psychological and lifestyle characteristics (physical activity, smoking habits, etc.) were recorded. In particular, nutritional habits, including coffee consumption, were evaluated using a semiquantitative food-frequency questionnaire. Multi-adjusted analysis revealed that in normotensive patients coffee consumption of 1-2 cups/day was associated with 88% (95% confidence interval, 0.02¬0.84) lower likelihood of developing LVSD and consumption of >3 cups/day with 90% (95% confidence interval, 0.01-0.88) lower likelihood for LVSD, compared with no history of consumption of coffee and after adjusting for various confounders. In contrast, in hypertensive patients coffee consumption of >3 cups/day was associated with 4.5-fold higher likelihood for developing LVSD (95% confidence interval, 0.89-22.58) as compared with no history of coffee consumption. Coffee consumption has opposite effects on the likelihood of developing LVSD in post-acute coronary syndrome patients depending on their blood pressure levels.

Source : J Med Food 2009 vol.12 (1), pp 29 - 36

Yang, J. N.; Chen, J. F.; Fredholm, B. B.

Heart rate (HR), body temperature (Temp), locomotor activity (LA), and oxygen consumption (O(2)C) were studied in awake mice lacking one or both of the adenosine A(1) or A(2A) receptors (A(1)R or A(2A)R, respectively) using telemetry and respirometry, before and after caffeine administration. All parameters were lower during day than night and higher in females than males. When compared with wild-type (WT) littermates, HR was higher in male A(1)R knockout (A(1)RKO) mice but lower in A(2A)RKO mice and intermediate in A(1)-A(2A)R double KO mice. A single dose of an unselective beta-blocker (timolol; 1 mg/kg) abolished the HR differences between these genotypes. Deletion of A(1)Rs had little effect on Temp, whereas deletion of A(2A)Rs increased it in females and decreased it in males. A(1)-A(2A)RKO mice had lower Temp than WT mice. LA was unaltered in A(1)RKO mice and lower in A(2A)RKO and A(1)-A(2A)RKO mice than in WT mice. Caffeine injection increased LA but only in mice expressing A(2A)R. Caffeine ingestion also increased LA in an A(2A)R-dependent manner in male mice. Caffeine ingestion significantly increased O(2)C in WT mice, but less in the different KO mice. Injection of 30 mg/kg caffeine decreased Temp, especially in KO mice, and hence in a manner unrelated to A(1)R or A(2A)R blockade. Selective A(2B) antagonism had little or no effect. Thus A(1)R and A(2A)R influence HR, Temp, LA, and O(2)C in mice in a sex-dependent manner, indicating effects of endogenous adenosine. The A(2A)R plays an important role in the modulation of O(2)C and LA by acute and chronic caffeine administration. There is also evidence for effects of higher doses of caffeine being independent of both A(1)R and A(2A)R.

Source : Am J Physiol Heart Circ Physiol 2009 vol.296 (4), pp H1141 - H1149

Akashi, I.; Kagami, K.; Hirano, T.; Oka, K.

The protective effects of coffee-derived compounds on lipopolysaccharide/D-galactosamine (LPS/D-GalN) induced acute liver injury in rats were investigated. METHODS: Wistar rats were orally administered saline (control) or one of the test compounds (caffeine, chlorogenic acid, trigonelline, nicotinic acid or eight pyrazinoic acids) at a dose of 100 mg/kg, respectively. This was followed by intraperitoneal injection with LPS (100 mug/kg)/D-GalN (250 mg/kg) 1 h after administration of the test compounds. Blood samples were collected up to 12 h after LPS/D-GalN injection, followed by determination of plasma aspartate aminotransferase, alanine aminotransferase, tumour necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) levels. KEY FINDINGS: Plasma aspartate aminotransferase and alanine aminotransferase levels were significantly increased after LPS/D-GalN-treatment, but were suppressed by pretreatment with caffeine (n = 5), nicotinic acid, non-substituted pyrazinoic acid or 5-methylpyrazinoic acid (n = 6, respectively) 12 h after LPS/D-GalN-treatment (P < 0.01, respectively). Moreover, the animals pretreated with these test compounds showed significantly higher survival rates (83-100%) compared with the control (23%). Only pretreatment with caffeine significantly suppressed the LPS/D-GalN induced elevation of plasma TNF-alpha levels 1 and 2 h after LPS/D-GalN-treatment (P < 0.01, respectively). Pretreatment with caffeine, nicotinic acid or non-substituted pyrazinoic acid activated the LPS/D-GalN induced elevation of plasma IL-10 levels at 1 and 2 h, although there were no statistically significant differences in IL-10 levels between control and nicotinic acid or non-substituted pyrazinoic acid treated rats.

CONCLUSIONS: The results suggest that caffeine, nicotinic acid, non-substituted pyrazinoic acid and 5-methylpyrazinoic acid can protect against LPS/D-GalN induced acute liver injury, which may be mediated by the reduction of TNF-alpha production and/or increasing IL-10 production.

Source : J Pharm Pharmacol 2009 vol.61 (4), pp 473 - 478

Serafini, M.; Testa, M. F.

Plant-based foods (such as fruit and vegetables, wine, nuts, natural vegetable oils, and whole grains) are an important component of traditional diets in Mediterranean regions. A large, consistent body of scientific evidence demonstrates that diets rich in plant foods provide protection against degenerative diseases; however, despite the consensus of the evidence about the health effect of plant foods, it is unclear which components of plant-based foods are protective and what their mechanism of action is. One of the hypotheses postulated to explain the protective effect of plant food, the antioxidant hypothesis, is based on their high content of bioactive molecules. Recent evidence suggests that it is the variegate composition of the plant food, an optimal mixture of different antioxidants endowed with complementary mechanism of action and different redox potential, which is at the basis of their effect on health. The global antioxidant efficiency of complex matrixes can be assessed by measuring their total antioxidant capacity (TAC) representing the result of variables such as redox potentials of the compounds present in the matrix and their cumulative and synergistic interaction. In the last years different databases for TAC of plant foods have been developed. Results suggest that coffee might represent a potential contributor to dietary antioxidant intake. In this contribution after describing the main contributors to dietary TAC for different plant food group, we will discuss the potentiality of coffee as a source of "ready to drink" reducing equivalents.

Source : Clin Dermatol 2009 vol.27 (2), pp 225 - 229

Hsu, T. L.; Bau, J. G.; Wang, W. K.; Li, S. P.; Wang, Y. Y.

Previously, we found that qi-stimulating events exerted similar frequency-specific effects on the blood pressure pulse spectrum. Because coffee and qi induce similar stimulatory psychological responses, we aimed to determine whether they would induce similar pulse effects. Such a relationship would suggest a close linkage between the physiologic mechanisms underlying the psychostimulatory responses and vascular effects of coffee and qi. Therefore, the profound investigations into the mechanisms underlying the effects of coffee on the central nervous system and the vascular system may help to elucidate the underlying physiology mechanisms of qi. METHODS: Each test subject took three rounds of 150 mL coffee (0.1 g/kg, 0.05 g/kg, 0.05 g/kg) in a 30-minute interval. The subject\'s pulses were recorded at the end of each round. The changes in the test subject\'s pulse spectrum between before and after coffee consumption were compared with changes induced by a water placebo. RESULTS: Both coffee and qi caused the intensities of the third, sixth, and ninth harmonics of the pressure pulse spectrum to be relative peaks to their neighboring harmonics. CONCLUSION: Our results suggest that the coffee effect may be considered a qi-stimulating event, and there is a common physiologic factor determining the psychostimulatory responses of qi and coffee as well as their effects on the cardiovascular system, which results in a specific frequency pattern in the blood pulse spectrum. Adenosine, which is the main physiologic compound affected by coffee, might also be the key factor affected by qi.

Source : J Altern Complement Med. 2008 vol. 14 (9), pp 1145 - 1150

Hulston, C. J.; Jeukendrup, A. E.

PURPOSE: 1) To investigate the effect of caffeine on exogenous carbohydrate (CHO) oxidation and glucose kinetics during exercise; and 2) to determine whether combined ingestion of caffeine and CHO enhanced cycling performance compared with CHO alone. METHODS: Ten endurance-trained cyclists performed three experimental trials consisting of 105 min steady-state (SS) cycling at 62% VO2max followed by a time trial (TT) lasting approximately 45 min. During exercise, subjects ingested either of the following: a 6.4% glucose solution (GLU), a 6.4% glucose plus caffeine solution providing 5.3 mg kg(-1) of caffeine (GLU + CAF), or a placebo (PLA). Glucose solutions contained a trace amount of [U-C]glucose, and eight subjects received a primed continuous [6,6-H2]glucose infusion. RESULTS: Peak exogenous CHO oxidation rates were not significantly different between GLU and GLU + CAF trials (52.6 +/- 2.7 and 49.1 +/- 2.1 micromol kg.min(-1), respectively). Rates of appearance (Ra) and disappearance (Rd) of glucose were significantly higher with CHO ingestion than PLA (P < 0.01) but were not significantly different between GLU and GLU + CAF trials. Performance times were 43.45 +/- 0.86, 45.45 +/- 1.07, and 47.40 +/- 1.30 min for GLU + CAF, GLU, and PLA, respectively. Therefore, GLU + CAF ingestion enhanced TT performance by 4.6% (P < 0.05) compared with GLU and 9% (P < 0.05) compared with PLA.

CONCLUSION: The coingestion of caffeine (5.3 mg kg(-1)) with CHO during exercise enhanced TT performance by 4.6% compared with CHO and 9.0% compared with water placebo. However, caffeine did not influence exogenous CHO oxidation or glucose kinetics during SS exercise.

Source : Med Sci Sports Exerc 2008  vol.40 (12), pp 2096 - 2104

Sin, C. W.; Ho, J. S.; Chung, J. W.

The aim of the present study is to review the effects of caffeine abstinence on the quality of sleep. BACKGROUND: Insomnia is a common problem and abstinence from caffeine is the most popular component in sleep hygiene advice. However, there have been inconsistent results relating to the effectiveness of caffeine abstinence in improving sleep. DESIGN: Systematic review. METHODS: We browsed several electronic databases and reference lists of articles about the correlation of caffeine consumption and sleep deprivation. We selected the articles according to predefined inclusion and exclusion criteria. Two reviewers assessed the quality of trials, which were selected according to the Jadad quality assessment scale. We included the trials scoring three or above in the systematic review and extracted their data. We assessed the heterogeneity of the studies before we considered whether or not to combine the studies\' results. RESULTS: Three randomised control trials fulfilled the selection criteria among which two trials scored > or =3 on the Jadad scale. We included these two trials in our systematic review. The designs and outcome measurements of these two trials were not homogeneous, therefore, we did not combine their results. Instead, we conducted a critical appraisal. In one trial, caffeine abstinence was associated with significant lengthening of sleep duration (p < 0.01) and better sleep quality (p < 0.05). In another trial, subjects had less difficulty falling asleep on days when they drank decaffeinated coffee (p < 0.05).

CONCLUSIONS: The results showed that caffeine abstinence for a whole day could improve sleep quality. Thus, health practitioners were recommended to include caffeine abstinence in the instructions for sleep hygiene. RELEVANCE TO CLINICAL PRACTICE: This study demonstrates the effectiveness of caffeine abstinence in improving sleep quality. It provides evidence for the practice of including caffeine abstinence in sleep hygiene advice.

Source : J Clin Nurs  2009 vol.18 (1), pp 13 - 21

Kennedy, M. D.; Galloway, A. V.; Dickau, L. J.; Hudson, M. K.

Most North American workers drink coffee throughout their workday, although the cumulative effect of job stress and coffee is not well known. Research has shown that coffee affects the cardiovascular system and mental alertness primarily through the active ingredient caffeine; however, the dose of caffeine used in these studies is greater than a normal cup of coffee. In addition, these changes have been mostly determined in male caffeine-habituated consumers. Therefore, this study examined the effect of a normal cup of coffee on the cardiovascular and mental alertness response both before and after a mental stress task in 10 caffeine-naive (23 +/- 5.0 years) and 10 caffeine-habituated (25 +/- 6 years) females. Blood pressure, heart rate, and mental alertness were taken at baseline (before coffee), 50 minutes after finishing coffee and immediately after a 9-minute mental stress task. The volume of coffee ingested for a 15-minute period was 350 mL (12 oz), which is equivalent to 140 mg of caffeine. The combined effect of coffee and mental stress significantly decreased diastolic blood pressure (Delta8 mm Hg) and increased heart rate (Delta6 beats per minute) and mental alertness (Delta67.3%) in caffeine-naive and caffeine-habituated females, whereas systolic blood pressure (Delta10.3 mm Hg) only increased in the caffeine-naive participants. Our results indicate that a normal cup of coffee can effect changes in blood pressure and mental alertness and that mental stress may alter the magnitude of change; however, the transient increase in systolic blood pressure after drinking coffee in caffeine-naive participants requires further investigation.

Source : Nutr Res 2008  vol.28 (9) pp 609 - 614

Lesk, V. E.; Honey, T. E.; de Jager, C. A.

We investigated the effect of recent intake of caffeine-containing foodstuffs (CCFS) on a group of elderly participants (age range 67-95 years) on a series of neuropsychological tests. There was no significant effect of CCFS intake on performance in any of the tests in the battery used. However, a significant interaction effect was found between age and CCFS consumption on scores of some neuropsychological tests. In these tests, participants with recent consumption of CCFS show a linear decrease in performance with increasing age, a pattern not seen for those that have no CCFS in their system. Accuracy in the neuropsychological assessment is of great importance when determining whether someone has a cognitive impairment or early Alzheimer\'s disease. We therefore propose that recent consumption of CCFS should be taken into account when scoring the neuropsychological assessment.

Source : Dement Geriatr Cogn Disord  vol.27 (4), pp 322 - 328

McNaughton, L. R.; Lovell, R. J.; Siegler, J.; Midgley, A. W.; Moore, L.; Bentley, D. J.

The purpose of this work was to determine the effects of caffeine on high intensity time trial (TT) cycling performance in well-trained subjects. SUBJECTS: Six male cyclists with the following physical characteristics (mean +/- SD) age 30.7 +/- 12, height 179.3 +/- 7.5 cm, mass 70.0 +/- 7.5 kg, VO2max 65.0 +/- 6.3 mL.kg-1.min-1 undertook three 1-h TT performances, control (C), placebo (P) and caffeine (CAF), on a Velotron cycle ergometer conducted in a double-blind, random fashion. Subjects rested for 60 min and were then given CAF or P in a dose of 6 mg.kg-1 body mass and then commenced exercise after another 60 min of rest. Before ingestion, 60 min postingestion, and at the end of the TT, finger-prick blood samples were analyzed for lactate. RESULTS: The cyclists rode significantly further in the CAF trial (28.0 +/- 1.3 km) than they did in the C (26.3 +/- 1.5 km, P < .01) or P (26.4 +/- 1.5 km, P < .02) trials. No differences were seen in heart rate data throughout the TT (P > .05). Blood lactate levels were significantly higher at the end of the trials than either at rest or postingestion (P < .0001), but there were no differences between the three trial groups.

CONCLUSION: On the basis of the data, we concluded that performance was improved with the use of a caffeine supplement.

Source : Int J Sports Physiol Perform 2008 vol.3 (2), pp 157 - 163

Kelsey, J. E.; Langelier, N. A.; Oriel, B. S.; Reedy, C.

RATIONALE AND OBJECTIVES: Given that adenosine A2A antagonists appear to be therapeutic in several animal models of Parkinson\'s disease (PD), we examined the extent to which caffeine and selective A2A and A1 antagonists could enhance contralateral forepaw stepping in the unilateral 6-OHDA-lesioned rat. MATERIALS AND METHODS: Following unilateral injections of 12 microg 6-OHDA into the medial forebrain bundle (MFB), frequency of stepping with both front paws was counted separately as the paws were dragged anteriorally and laterally by a treadmill. RESULTS: The MFB lesions decreased contralateral stepping by 74-83%, and 8 mg/kg 3,4-dihydroxy-L-phenylalanine (L-DOPA) increased contralateral stepping by 25-26%. Caffeine given systemically (15 mg/kg) or into the dorsal striatum or external globus pallidus (GPE; 20-40 microg) increased contralateral forepaw stepping by 14%, 27%, and 26%, respectively, and enhanced the effect of 8 mg/kg L-DOPA on stepping. The selective A(2A) antagonist SCH-58261 (2 mg/kg) also increased stepping by 13% and enhanced the therapeutic effect of L-DOPA, whereas the selective A(1) [corrected] antagonist 8-cyclopentyltheophylline (3-7 mg/kg) and A(1) agonist N(6)-cyclopentyladenosine (0.03-0.2 mg/kg) had no effect. None of these drugs appeared to produce dyskinesic effects. CONCLUSIONS: In this well-validated animal model of the akinesic effects of PD, caffeine and a selective A2A, but not an A1, antagonist were able to provide both monotherapeutic and adjunctive therapeutic effects. These data are consistent with the hypothesis that A2A antagonists may be therapeutic in human PD patients and indicate that the dorsal striatum and GPE are critical sites of therapeutic action.

Source : Psychopharmacology (Berl) 2009 vol.201 (4), pp 529 - 539

Kapur, R.; Smith, M. D.

Caffeine overdoses produce multiple symptoms, most of which are commonly associated with a marked increase in adrenergic tone. These can include hypertension, tachycardia, dysrhythmias, and central nervous and skeletal muscle stimulation. This case illustrates a massive caffeine ingestion with resultant cardiovascular collapse. The patient was stabilized with a combination of lidocaine and phenylephrine in the emergency department and underwent hemodialysis in the intensive care unit, with rapid extubation
and return to baseline functioning. To our knowledge, this combination has not been previously used to treat massive caffeine ingestions.

Source : Am J Emerg Med  2009 vol.27 (2), pp 253 - 256 

Arisseto, A. P.; Figueiredo-Toledo, M. C.; Govaert, Y.; Loco, J. van; Fraselle, S.; Degroodt, J. M.

A modified sample preparation for acrylamide determination in difficult matrices such as cocoa and coffee by a liquid chromatography-tandem mass spectrometry method is presented in this work. For the sample pretreatment, different solvents, purification steps, and solid-phase extraction cartridges were evaluated. The analyses were carried out on a mu-Bondapak C18 column using acrylamide-D3 as internal standard. For identification and confirmation of acrylamide, relative retention time and two diagnostic ions were monitored. Good performance of the method was achieved by introducing a protein precipitation step with Carrez I and II solutions and a liquid-liquid extraction with ethyl acetate in combination with solid-phase extraction during the sample clean-up. A limit of detection of 10 mug/kg, a limit of quantitation of 20 mug/kg, mean recoveries ranging from 93 to 99%, coefficients of variation of 3.4% for repeatability, and from 1.7 to 10.8% for within-laboratory reproducibility were obtained during a laboratory validation procedure.

Source : Food Anal Meth 2008 vol.1 (1), pp 49 - 55

Perez-Martinez, M.; Sopelana, P.; Paz-de-Pena, M.; Cid, C.

This study aimed to obtain a black coffee brew that could be consumed hot, by extending its shelf life with the addition of additives. 4 pH-regulator agents (sodium and potassium carbonates and bicarbonates), 1 pH regulator and antioxidant (sodium citrate), 3 antioxidants (sodium ascorbate, EDTA and sodium sulfite) and lactoserum were tested by sensory analysis. Sodium carbonate and bicarbonate were selected for a study of physicochemical (soluble and volatile compounds related to sensory properties) and sensorial quality of coffee brew stored for 90 days at 4°C. Although both additives extended the shelf life of the coffee brew up to 60 days, sodium carbonate was the chosen additive because it was the most useful in limiting pH decrease and perception of sourness, which are some of the main factors involved in rejection of stored coffee brews, and it better maintained aroma and taste/flavour. Moreover, application of multivariate analysis facilitated 1st the description of global changes of coffee brews with or without additives throughout storage using principal component analysis and 2nd the obtainment of a simple equation with only pH and caffeic acid parameters to discriminate the 3 types of coffee brews and simplify the analytical process, by means of stepwise discriminant analysis.

Source : J Agric Food Chem 2008 vol.56 (24), pp 11845 - 11853

Andueza, S.; Manzocco, L.; Paz, de Pena; Cid, C.; Nicoli, C.

The potential of phenol antioxidants to undergo decomposition reactions leading to the formation of products showing prooxidant activity was examined in this study. A hydroalcoholic solution containing caffeic acid was examined for its antioxidant and prooxidant activity during heating, to simulate heat maintenance of coffee brews. Decomposition products were evaluated. A mechanistic route of caffeic acid decomposition under thermal conditions is proposed. Caffeic acid acted as an antioxidant and prooxidant, as a result of thermal decomposition.

Source : Food Res Intern 2009 vol.42 (1), pp 51-55

Rosal, R.; Rodriguez, A.; Perdigon-Melon, J. A.; Petre, A.; Garcia-Calvo, E.; Gomez, M. J.; Aguera, A.; Fernandez-Alba, A. R.

The ozonation of caffeine in water was performed at different pH values, including acidic conditions. Kinetic experiments were conducted by adding pulses of a concentrated caffeine solution to ozone saturated water. The results showed a rapid decrease of ozone concentration during the first 15s after injection, followed by a gradual decline at a much slower rate. The data were fitted to a second order kinetic model with rate constants increasing from 0.25 to 1.05 M(-1)s(-1) for pH in the 3-10 range. The initial ozone consumption per mol of ozonated caffeine was greater at high pH values, reflecting a higher ozone decomposition rate. The decomposition of ozone was positively affected by the concentration of caffeine, an effect that could be attributed to the presence of a reaction intermediate from the ozonation of caffeine that behaved as a strong promoter of ozone decomposition. A study of the transformation products identified by liquid chromatography in combination with time-of-flight mass spectrometry was carried out, which permitted a tentative degradation pathway to be proposed and several persistent by¬products to be identified at both pH 3 and 8. Most transformation products were the result of the opening of the imidazole ring after breaking caffeine\'s N9C8 double bond.

Source :  Chemosphere 2009 vol.74 (6), pp 825 - 831

Bianco, G.; Abate, S.; Labella, C.; Cataldi, T. R.

Liquid chromatography (LC) with positive ion electrospray ionization (ESI+) coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) was employed for the simultaneous determination of caffeine and its metabolites in human urine within a single chromatographic run. LC/ESI-FTICRMS led to the unambiguous determination of the molecular masses of the studied compounds without interference from other biomolecules. A systematic and comprehensive study of the mass spectral behaviour of caffeine and its fourteen metabolites by tandem mass spectrometry (MS/MS) was performed, through in-source ion trap collision-induced dissociation (CID) of the protonated molecules, [M+H](+). A retro-Diels-Alder (RDA) process along  with ring-contraction reactions were the major fragmentation pathways observed during CID. The base peak of xanthine precursors originates from the loss of methyl isocyanate (CH(3)NCO, 57 Da) or isocyanic acid (HNCO, 43 Da), which in turn lose a CO unit. Also uric acid derivatives shared a RDA rearrangement as a common fragmentation process and a successive loss of CO(2) or CO. The uracil derivatives showed a loss of a ketene unit (CH(2)CO, 42 Da) from the protonated molecule along with the loss of H(2)O or CO. To assess the potential of the present method three established metabolite ratios to measure P450 CYP1A2, N-acetyltransferase and xanthine oxidase activities were evaluated by a number of identified metabolites from healthy human urine samples after caffeine intake.

Source : Rapid Commun.Mass Spectrom 2009 vol.23 (7), pp 1065 - 1074

Alonso-Salces, R. M.; Guillou, C.; Berrueta, L. A.

Liquid chromatography coupled with a photodiode array detector, electrospray ionization, collision-induced dissociation and tandem mass spectrometry (LC-DAD/ESI-CID-MS/MS) on a triple quadrupole (QqQ) has been used to detect and characterize polyphenols and methylxanthines in green coffee beans: three phenolic acids (caffeic acid, ferulic acid and dimethoxycinnamic acid), three isomeric caffeoylquinic acids (M(r) 354), three feruloylquinic acids (M(r) 368), one p-coumaroylquinic acid (M(r) 338), three dicaffeoylquinic acids (M(r) 516), three feruloyl-caffeoylquinic acids (M(r) 530), four p-coumaroyl-caffeoylquinic acids (M(r) 500), three diferuloylquinic acids (M(r) 544), six dimethoxycinnamoyl-caffeoylquinic acids (M(r) 544), three dimethoxycinnamoyl-feruloylquinic acids (M(r) 558), six cinnamoyl-amino acid conjugates, three cinnamoyl glycosides, and three methylxanthines (caffeine, theobromine and theophylline). Dimethoxycinnamic acid, three isomers of dimethoxycinnamoyl-caffeoylquinic acids and another three of dimethoxycinnamoyl-feruloylquinic acids, as well as the three cinnamoyl glycosides, had not previously been reported in coffee beans. Structures have been assigned on the basis of the complementary information obtained from UV-visible spectra, relative hydrophobicity, scan mode MS spectra, and fragmentation patterns in MS(2) spectra (both in the positive and negative ion modes) obtained using a QqQ at different collision energies. A structure diagnosis scheme is provided for the identification of different isomers of polyphenols and methylxanthines.

Source : Rapid Commun Mass Spectrom 2009 vol.23 (3), pp 363 - 383

Ribeiro, J. S.; Augusto, F.; Salva, T.-J. G.; Thomaziello, R. A.; Ferreira, M.-M. C.

With the aim of developing an analytical method for determination of the sensory properties of roasted coffee, volatile compounds composition of 58 samples of arabica coffee from Brazil was analysed using solid phase microextraction followed by GC-FID or GC-MS. The samples were also subjected to sensory analysis for assessment of body, flavour, cleanliness and overall quality. Partial least squares calibration of the volatile compounds profiles for prediction of each sensory attribute studied was performed (correlation optimized warping and ordered predictors selection algorithms were first applied to the chromatographic data) and discriminant analysis was used to differentiate samples of differing overall quality. Potential chemical markers of overall quality were identified using the method and include 3-methylpropanal, 2-methylfuran, furfural, furfuryl formate, 5-methyl-2-furancarboxyaldehyde, 4-ethylguaiacol, 3-methylthiophene, 2-furanmethanol acetate, 2-ethyl-3,6-dimethylpyrazine and 1-(2-furanyl)-2-butanone.

Source : Analytica Chimica Acta 2009 vol.634(2), pp 172 - 179

Romero-Gonzalez, R. R.; Verpoorte, R.

In addition to sample solubility constraints, the use of polarity gradients in normal-phase centrifugal partition chromatography (CPC) for the purification of complex mixtures is also limited by the instability of biphasic systems as a consequence of dramatic changes in the settling times along the gradient, leading in many cases to column bleeding when working under maximum efficiency conditions. In this paper an electrostriction approach is proposed as a strategy in reversed-phase CPC to fractionate intermediate polarity extracts in a single run by bringing its components into the "sweet spot" in a controlled fashion through a stepwise reduction of salt concentration in the aqueous mobile phase. The salting-out gradient method was successfully tested with the separation of the major chlorogenic acids (CGAs, hydroxycinnamoylquinic acids) present in green coffee beans (5-caffeoylquinic acid (5-CQA), 5-feruloylquinic acid (5-FQA) and 3,5-dicaffeoylquinic acid (3,5-diCQA)) using ethyl acetate-hexane as the stationary phase and an ionic gradient of LiCl (5.0, 2.5 and 0.1M) as the mobile phase in one case and (NH(4))(2)SO(4)/KNO(3) (3.0 and 1.5M/1.5M) in another. Regioisomers of each chlorogenic acid obtained by base-catalyzed isomerisation were also separated by CPC using isocratic elution. The best resolution for both FQAs and diCQAs was achieved with a chloroform-n-butanol-0.01M pH 2.5 phosphate buffer (84:16:100; v/v) system, while CQAs were best isolated using chloroform-n-butanol-0.01M pH 2.5 phosphate buffer/5.0M LiCl (82:18:100; v/v).

Source : J Chromatogr A vol.1216 (19), pp 4245 - 4251

Chiralertpong, A.; Acree, T. E.; Barnard, J.; Siebert, K. J.

Espresso coffee samples were freshly prepared with 10% sucrose, 0.0143% sucralose (equivalent in sweetness to 10% sucrose), or unsweetened, each with and without nondairy creamer. A sensory panel rated the intensities of \'malty\', \'caramel\', \'roasty\' and \'coffee-like\' sensory properties. The concn. of flavour chemicals associated with the latter 3 sensations (furaneol, 2-ethyl-3,5-dimethyl (EDM) pyrazine and 2-furfuryl thiol, respectively) were determined by GC, using solid-phase microextraction sampling of coffee headspace. Furaneol and furfuryl thiol were essentially unaffected by creamer addition, but the more nonpolar EDM pyrazine was greatly reduced. The malty, caramel, roasty, and coffee-like flavour intensities were not significantly affected by creamer addition. This appears to be a case of disconnect between the absence of an aroma compound and perception. Furaneol, furfuryl thiol, and EDM pyrazine concn. were unaffected by adding either sweetener. The malty sensation was the same with and without added sweetener. The roasty and coffee-like ratings both decreased to similar extents in the samples with the 2 added sweeteners. The ratings for caramel were considerably increased, again to a similar extent, by both sweeteners. Since the added sweeteners were both nonvolatile, this is clearly a case where taste affected aroma perception.

Source : Chemosensory Perception 2008 vol.1 (2), pp 147 - 152

Rufian-Henares, J. A.; Cueva, S.-P. de-la

Melanoidins comprise a substantial proportion of severely heat-treated foods such as baked cereals or roasted coffee and are widely consumed dietary components. Antimicrobial activity of coffee melanoidins against different pathogenic bacteria was studied, and it was found that such activity was due to their metal-chelating properties. 3 different mechanisms were observed: at low concn., melanoidins exerted bacteriostatic activity mediated by Fe chelation from the culture medium; in the case of bacterial strains that were able to produce siderophores for Fe acquisition, melanoidins chelated the siderophore-Fe3+ complex, which could decrease the virulence of such pathogenic bacteria; and, finally, coffee melanoidins also exerted bactericidal activity at high concn. by removing Mg2+ cations from the outer membrane, promoting the disruption of the cell membrane and allowing the release of intracellular molecules.

Sourece : J Agric Food Chem.2009 vol.57(2), pp 432 - 438

Clarindo, W. R.; Carvalho, C. R.

Nuclear genome size has been measured in various plants, seeing that knowledge of the DNA content is useful for taxonomic and evolutive studies, plant breeding programs and genome sequencing projects. Besides the nuclear DNA content, tools and protocols to quantify the chromosomal DNA content have been also applied, expanding the data about genomic structure. This study was conducted in order to calculate the Coffea canephora and Coffea arabica chromosomal DNA content, associating cytogenetic methodologies with flow cytometry (FCM) and image cytometry (ICM) tools. FCM analysis showed that the mean nuclear DNA content of C. canephora and C. arabica is 2C = 1.41 and 2.62 pg, respectively. The cytogenetic methodology provided prometaphase and metaphase cells exhibiting adequate chromosomes for the ICM measurements and karyogram assembly. Based on cytogenetic, FCM and ICM results; it was possible to calculate the chromosomal DNA content of the two species. The 1C chromosomal DNA content of C. canephora ranged from 0.09 (chromosome 1) to 0.05 pg (chromosome 11) and C. arabica from 0.09 (chromosome 1) to 0.03 pg (chromosome 22). The methodology presented in this study was suitable for DNA content measuring of each chromosome of C. canephora and C. arabica. The cytogenetic characterization and chromosomal DNA content analyses evidenced that C. arabica is a true allotetraploid originated from a cross between Coffea diploid species. Besides, the same analyses also reinforce that C. canephora is a possible progenitor of C. arabica.

Source :  Plant Cell Rep 2009 vol.28 (1), pp 73 - 81

Joet, T.; Laffargue, A.; Salmona, J.; Doulbeau, S.; Descroix, F.; Bertrand, B.; de Kochko, A.; Dussert, S.

The genomic era facilitates the understanding of how transcriptional networks are interconnected to program seed development and filling. However, to date, little information is available regarding dicot seeds with a transient perisperm and a persistent, copious endosperm. Coffea arabica is the subject of increasing genomic research and is a model for nonorthodox albuminous dicot seeds of tropical origin. The aim of this study was to reconstruct the metabolic pathways involved in the biosynthesis of the main coffee seed storage compounds, namely cell wall polysaccharides, triacylglycerols, sucrose, and chlorogenic acids. For this purpose, we integrated transcriptomic and metabolite analyses, combining real-time RT-PCR performed on 137 selected genes (of which 79 were uncharacterized in Coffea) and metabolite profiling.  Our map-drawing approach derived from model plants enabled us to propose a rationale for the peculiar traits of the coffee endosperm, such as its unusual fatty acid composition, remarkable accumulation of chlorogenic acid and cell wall polysaccharides. * Comparison with the developmental features of exalbuminous seeds described in the literature revealed that the two seed types share important regulatory mechanisms for reserve biosynthesis, independent of the origin and ploidy level of the storage tissue.

Source :  New Phytol 2009 vol. 182 (1), pp 146 - 162