Hydrogen peroxide and coffee induce G:C-->T:A transversions in the lacI gene of catalase-defective Escherichia coli.
(9/677)
The mutagenicity of hydrogen peroxide (H2O2) was compared with that of coffee, a complex mixture which generates H2O2. An Escherichia coli strain defective in catalase activity (katG katE double mutant) and carrying a single copy mucAB (pRW144) plasmid was constructed to enhance the mutagenic response to oxidants. The ability of the mucAB genes to influence the type, frequency and distribution of H2O2-induced mutations was also investigated in isogenic bacteria lacking pRW144. Induced mutational spectra were characterized and compared with that of spontaneous mutagenesis. A total of 444 independent forward mutations affecting the first 210 bp of the lacI gene were identified by DNA sequence analysis. The spontaneous mutation spectrum showed no bias (P = 0.52) for substitutions at G:C base pairs. In contrast, in the H2O2-induced spectrum substitutions occurred preferentially at G:C base pairs (P < 0.0001) with a preponderance of G:C-->T:A transversions (43.4% of H2O2-induced mutants versus 17.3% of spontaneous mutants). These data support the view that 7,8-dihydro-8-oxoguanine is the main premutagenic lesion induced by H2O2 and that catalase-defective bacteria have elevated levels of 8-oxoguanine in chromosome DNA after H2O2 exposure. Coffee produced a similar distribution of mutational events as H2O2 (P > 0.05), suggesting that this compound may be the main cause of the coffee-induced mutagenesis. The presence of plasmid pRW144 did not affect the frequency of H2O2-induced G:C-->T:A transversions, but caused an increase in A:T-->T:A transversions and a decrease in -1 base frameshifts. Although the frequencies of G:C-->T:A transversions were similar in all three induced spectra (H2O2 and coffee +/- pRW144), differences were observed in location of mutations throughout the target gene. (+info)
Coffee and tea consumption in the Scottish Heart Health Study follow up: conflicting relations with coronary risk factors, coronary disease, and all cause mortality.
(10/677)
STUDY OBJECTIVE: To relate habitual (cups per day) tea and coffee consumption to conventional coronary risk factors and subsequent risk of coronary heart disease and death. DESIGN: Cohort study. SETTING: Nationwide random population study. PARTICIPANTS: Over 11,000 men and women aged 40-59 who took part in the Scottish Heart Health Study lifestyle and risk factor survey in 1984-87. Participants were followed up to the end of 1993, an average of 7.7 years, for all cause mortality, coronary death, or any major coronary event (death, non-fatal infarction or coronary artery surgery). Cox's proportional hazards regression model was used to estimate the hazard in consumers of tea and coffee relative to the zero consumption group, both before and after correction for other factors. MAIN RESULTS: Coffee and tea consumption showed a strong inverse relation. For many conventional risk factors, coffee showed a weak, but beneficial, gradient with increasing consumption, whereas increasing tea consumption showed the reverse. Increasing coffee consumption was associated with beneficial effects for mortality and coronary morbidity, whereas tea showed the opposite. Adjusting for age and social class had some effect in reducing associations. Multiple adjustment for other risk factors removed the associations for tea and most of those for coffee although there was a residual benefit of coffee consumption in avoiding heart disease among men. CONCLUSIONS: The epidemiological differences shown in this study occurred despite the pharmacological similarities between tea and coffee. Either they differ more than is realised, or they identify contrasting associated lifestyle and health risks, for which this multiple adjustment was inadequate. (+info)
Lifestyle and cardiovascular disease risk factors as determinants of total cysteine in plasma: the Hordaland Homocysteine Study.
(11/677)
BACKGROUND: Plasma total homocysteine (tHcy) is a cardiovascular disease risk factor and is related to several components of the established cardiovascular disease risk profile. Cysteine is structurally and metabolically related to homocysteine, but data on its association with cardiovascular disease and cardiovascular disease risk factors are sparse. OBJECTIVE: Our objective was to search for the determinants of plasma total cysteine (tCys) and compare them with those of tHcy. DESIGN: In this cross-sectional study, we studied 7591 healthy men and 8585 healthy women aged 40-67 y with no history of hypertension, diabetes mellitus, coronary heart disease, or cerebrovascular disease. RESULTS: In the group aged 40-42 y, tCys was significantly higher in men (&mean;: 273 micromol/L; 2.5-97.5 percentile: 219-338 micromol/L) than in women (253 micromol/L; 202-317 micromol/L) (P < 0.001). In the group aged 65-67 y, there was no significant sex difference in tCys: men (296 micromol/L; 233-362 micromol/L) and women (296 micromol/L; 234-361 micromol/L). As with tHcy, tCys was positively associated with age, total cholesterol concentration, diastolic blood pressure, and coffee consumption. Body mass index was a strong determinant of tCys but was not related to tHcy. Several factors known to influence tHcy, including smoking status, folate and vitamin intake, heart rate, and physical activity, were not associated or were only weakly associated with tCys. CONCLUSION: Plasma tCys is strongly related to several factors that constitute the cardiovascular disease risk profile. This should be an incentive to determine the role of tCys in cardiovascular disease. (+info)
Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: a randomized trial.
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BACKGROUND: An elevated plasma homocysteine concentration is a putative risk factor for cardiovascular disease. Observational studies have reported an association between coffee consumption and plasma homocysteine concentrations. OBJECTIVE: We studied the effect of coffee consumption on plasma homocysteine in a crossover trial. We used unfiltered coffee so as to include the possible effects of coffee diterpenes, which are removed by filtering. DESIGN: Sixty-four healthy volunteers (31 men and 33 women) with a mean (+/-SD) age of 43 +/- 11 y were randomly assigned to 2 groups. One group (n = 30) drank 1 L unfiltered cafetiere (French press) coffee daily for 2 wk. Such coffee is rich in the cholesterol-raising diterpenes kahweol and cafestol. The other group (n = 34) received water, milk, broth, tea, and chocolate drinks instead of coffee. After a washout period of 8 wk, both groups received the alternate intervention for another 2 wk. RESULTS: Consumption of 1 L unfiltered coffee/d for 2 wk significantly raised fasting plasma homocysteine concentrations by 10%, from 12.8 to 14.0 micromol/L. CONCLUSIONS: Unfiltered coffee increases plasma homocysteine concentrations in volunteers with normal initial concentrations. It is unclear whether the effect is caused by the cholesterol-raising diterpenes present exclusively in unfiltered coffee or by factors that are also present in filtered coffee. (+info)
Coffee and doughnut maculopathy: a cause of acute central ring scotomas.
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AIMS: To report the clinical features of five patients with non-progressive central ring scotomas of acute onset associated with excellent retained visual acuity. METHODS: Complete neuro-ophthalmological examinations were performed. Visual fields were performed by tangent screen, Goldmann, or Humphrey perimetry. In some cases further testing was carried out including fundus photography, fluorescein angiography, ERG, VEP, and neuroimaging. RESULTS: The patients were three women and two men whose ages ranged from 25 to 57 years. Four patients were heavy caffeine consumers while the fifth patient experienced an episode of hypotension. Vision loss was acute in all cases. The onset of vision loss was bilateral/simultaneous in three cases, bilateral/sequential in one case, and unilateral in one case. All affected eyes retained visual acuities of 20/25 or better. Colour vision was subnormal in three of four cases. Visual field defects were characterised by a central ring scotoma having an outer diameter less than 10 degrees. Fundus examination demonstrated temporal optic nerve pallor in three patients (five of 10 affected eyes) and reddish, petaloid macular lesions in one patient. Good visual acuity was maintained for the duration of follow up in all five patients. CONCLUSION: Central ring scotomas with excellent retained visual acuity may present as an acute, bilateral syndrome in patients who are heavy caffeine consumers. The configuration of visual field loss and its location, combined with the presence of temporal pallor in five eyes, suggest that the defect localises to the inner layers of the macula. While these cases could be considered an expansion of the clinical spectrum of acute macular neuroretinopathy, some may represent a distinct entity. (+info)
Association between coffee drinking and K-ras mutations in exocrine pancreatic cancer. PANKRAS II Study Group.
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STUDY OBJECTIVE: To analyse the relation between coffee consumption and mutations in the K-ras gene in exocrine pancreatic cancer. DESIGN: Case-case study. Consumption of coffee among cases with the activating mutation in the K-ras gene was compared with that of cases without the mutation. SETTING AND PATIENTS: All cases of pancreatic cancer newly diagnosed at five hospitals in Spain during three years were included in the PANKRAS II Study (n = 185, of whom 121 whose tissue was available for molecular analysis are the object of the present report). Over 88% were personally interviewed in hospital. DNA was amplified from paraffin wax embedded tissues, and mutations in codon 12 of K-ras were detected by the artificial RFLP technique. MAIN RESULTS: Mutations were found in tumours from 94 of 121 patients (77.7%). Mutations were more common among regular coffee drinkers than among non-regular coffee drinkers (82.0% v 55.6%, p = 0.018, n = 107). The odds ratio adjusted by age, sex, smoking and alcohol drinking was 5.41 (95% CI 1.64, 17.78). The weekly intake of coffee was significantly higher among patients with a mutated tumour (mean of 14.5 cups/week v 8.8 among patients with a wild type tumour, p < 0.05). With respect to non-regular coffee drinkers, the odds ratio of a mutated tumour adjusted by age, sex, smoking and alcohol drinking was 3.26 for drinkers of 2-7 cups/week, 5.77 for drinkers of 8-14 cups/week and 9.99 for drinkers of > or = 15 cups/week (p < 0.01, test for trend). CONCLUSIONS: Pancreatic cancer cases without activating mutations in the K-ras gene had drank significantly less coffee than cases with a mutation, with a significant dose response relation: the less they drank, the less likely their tumours were to harbour a mutation. In exocrine pancreatic cancer the K-ras gene may be activated less often among non-regular coffee drinkers than among regular drinkers. Caffeine, other coffee compounds or other factors with which coffee drinking is associated may modulate K-ras activation. (+info)
Effects of coffee consumption against the development of liver dysfunction: a 4-year follow-up study of middle-aged Japanese male office workers.
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The association of coffee consumption with the development of increased serum aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) activities over 4 years was studied in 1221 liver dysfunction-free (serum AST and ALT < or = 39 IU/l and no medical care for or no past history of liver disease) Japanese male office workers aged 35 to 56 years. From the analysis using the Kaplan-Meier method, the estimated incidence of serum AST and/or ALT > or = 40 IU/l, > or = 50 IU/l, and > or = 60 IU/l decreased with an increase in coffee consumption. From the Cox proportional hazards model, coffee drinking was independently inversely associated with the development of serum AST and/or ALT > or = 40 IU/l (p = 0.019 by test for tendency), > or = 50 IU/l (p = 0.002), and > or = 60 IU/l (p = 0.007), controlling for age, body mass index, alcohol intake, and cigarette smoking. These results suggest that coffee may be protectively against the liver dysfunction in middle-aged Japanese men. (+info)
Tea drinking and bone mineral density in older women.
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BACKGROUND: High caffeine intake is reportedly a risk factor for reduced bone mineral density (BMD) in women. Most studies, however, are from populations in which coffee drinking predominates and is the major caffeine source. Tea contains caffeine but also has other nutrients, such as flavonoids, that may influence bone mass in different ways. OBJECTIVE: We examined the relation between tea drinking and BMD in older women in Britain, where tea drinking is common. METHODS: We measured BMD at the lumbar spine, femoral neck, greater trochanter, and Ward's triangle in 1256 free-living women aged 65-76 y in Cambridge, United Kingdom. Tea drinking was assessed by self-completed questionnaire and women were categorized as tea drinkers or non-tea drinkers. RESULTS: There were 1134 tea drinkers (90.3%) and 122 non-tea drinkers (9.7%). Compared with non-tea drinkers, tea drinkers had significantly greater ( approximately 5%) mean BMD measurements, adjusted for age and body mass index, at the lumbar spine (0.033 g/cm(2); P = 0.03), greater trochanter (0.028 g/cm(2); P = 0.004), and Ward's triangle (0.025 g/cm(2); P = 0.02). Differences at the femoral neck (0.013 g/cm(2)) were not significant. These findings were independent of smoking status, use of hormone replacement therapy, coffee drinking, and whether milk was added to tea. CONCLUSIONS: Older women who drank tea had higher BMD measurements than did those who did not drink tea. Nutrients found in tea, such as flavonoids, may influence BMD. Tea drinking may protect against osteoporosis in older women. (+info)