Single-locus inheritance in the allotetraploid Coffea arabica L. and interspecific hybrid C. arabica x C. canephora.
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Molecular cytogenetic analysis has indicated that Coffea arabica is an amphidiploid formed from the hybridization between two closely related diploid progenitor species, C. canephora and C. eugenioides. Our aim was to determine the mode of inheritance in C. arabica and in a tetraploid interspecific hybrid (called arabusta) between C. arabica and C. canephora as revealed by segregation analyses of restriction fragment length polymorphism (RFLP) loci markers. The observed RFLP allele segregations in an F(2) progeny of C. arabica conform to disomic inheritance as expected, with regular bivalent pairing of homologous chromosomes in the F1 hybrid. In contrast, RFLP loci followed tetrasomic inheritance in the arabusta interspecific hybrid, although bivalents have been reported to predominate greatly at meiosis in its hybrid. These results suggest that homologous chromosomes do not pair in C. arabica, not as a consequence of structural differentiation, but because of the functioning of pairing regulating factors. Moreover, the arabusta hybrid seems to offer the possibility of gene exchange between the homologous genomes. (+info)
Polymorphisms in biotransformation enzymes and the risk for recurrent early pregnancy loss.
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An imbalance between phase I drug metabolizing enzymes and phase II detoxification enzymes may contribute to the development of pre-eclampsia. Polymorphic variants in the phase I enzyme, cytochrome P450 genes may lead to increased toxification, whereas polymorphisms in the phase II enzyme, glutathione S-transferase genes may result in impaired detoxification. Most abundant in placenta and decidua is glutathione S-transferase P1-1, which may therefore be of particular importance in reproduction. We studied the frequencies of polymorphic variants in those enzymes in 187 women with recurrent early pregnancy loss and in 109 women with an uncomplicated obstetric history. DNA was extracted and subsequently polymerase chain reaction based genotyping assays were used. chi(2)-Analysis and Fisher's exact test were used for statistical evaluation. The glutathione S-transferase P1b-1b genotype was found significantly more often in women with recurrent early pregnancy loss than in controls (12% versus 5%, P = 0.03), in particular in those who consumed coffee (P = 0.02) or smoked cigarettes (P = 0.04). Polymorphisms in other glutathione S-transferase and cytochrome P450 genes occurred equally frequently in cases and controls. In conclusion, the occurrence of the glutathione S-transferase P1b-1b genotype, leading to lower glutathione S-transferase Pi enzyme activity and consequently to impaired placental detoxification, may represent a risk factor for recurrent early pregnancy loss. (+info)
Caffeine during pregnancy? In moderation.
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QUESTION: Many of my female patients, those who plan pregnancy or have conceived, are afraid of any intake of caffeine. This often makes their lives miserable during pregnancy. Is this justified scientifically? ANSWER: Motherisk's recent meta-analysis suggests that the risks for miscarriage and fetal growth retardation increase only with daily doses of caffeine above 150 mg/d, equivalent to six typical cups of coffee a day. It is possible that some of this presumed risk is due to confounders, such as cigarette smoking. (+info)
Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability of dietary iron.
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BACKGROUND: Dietary iron absorption from a meal is determined by iron status, heme- and nonheme-iron contents, and amounts of various dietary factors that influence iron absorption. Limited information is available about the net effect of these factors. OBJECTIVE: The objective was to develop an algorithm for predicting the effects of factors known to influence heme- and nonheme-iron absorption from meals and diets. DESIGN: The basis for the algorithm was the absorption of iron from a wheat roll (22.1 +/- 0.18%) containing no known inhibitors or enhancers of iron absorption and adjusted to a reference dose absorption of 40%. This basal absorption was multiplied by the expected effect of different amounts of dietary factors known to influence iron absorption: phytate, polyphenols, ascorbic acid, meat, fish and seafood, calcium, egg, soy protein, and alcohol. For each factor, an equation describing the dose-effect relation was developed. Special considerations were made for interactions between individual factors. RESULTS: Good agreement was seen when measurements of iron absorption from 24 complete meals were compared with results from use of the algorithm (r(2) = 0.987) and when mean iron absorption in 31 subjects served a varied whole diet labeled with heme- and nonheme-iron tracers over a period of 5 d was compared with the mean total iron absorption calculated by using the algorithm (P = 0.958). CONCLUSIONS: This algorithm has several applications. It can be used to predict iron absorption from various diets, to estimate the effects expected by dietary modification, and to translate physiologic into dietary iron requirements from different types of diets. (+info)
Cigarettes and suicide: a prospective study of 50,000 men.
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OBJECTIVES: This study examined the relation between smoking and suicide, controlling for various confounders. METHODS: More than 50,000 predominantly White, middle-aged and elderly male health professionals were followed up prospectively with biennial questionnaires from 1986 through 1994. The primary end point was suicide. Characteristics controlled for included age, marital status, body mass index, physical activity, alcohol intake, coffee consumption, and history of cancer. RESULTS: Eighty-two members of the cohort committed suicide during the 8-year follow-up period. In age-adjusted analyses with never smokers as the comparison group, the relative risk of suicide was 1.4 (95% confidence interval [CI] = 0.8, 2.3) among former smokers, 2.6 (95% CI = 0.9, 7.5) for light smokers (< 15 cigarettes/day), and 4.5 (95% CI = 2.3, 8.8) among heavier smokers. After adjustment for potential confounders, the relative risks were 1.4 (95% CI = 0.9, 2.4), 2.5 (95% CI = 0.9, 7.3), and 4.3 (95% CI = 2.2, 8.5), respectively. CONCLUSION: We found a positive, dose-related association between smoking and suicide among White men. Although inference about causality is not justified, our findings indicate that the smoking-suicide connection is not entirely due to the greater tendency among smokers to be unmarried, to be sedentary, to drink heavily, or to develop cancers. (+info)
Coffee consumption, rheumatoid factor, and the risk of rheumatoid arthritis.
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BACKGROUND: Recent epidemiological studies have suggested that smoking is a risk factor for rheumatoid factor (RF) positive rheumatoid arthritis (RA). Being overweight, high serum cholesterol, and dietary factors have in some studies been found to be associated with the risk of RA. No attention, however, has been paid to coffee consumption as a risk determinant, though it is a shared covariate of the alleged risk factors. OBJECTIVES: This study aimed at examining coffee consumption for its associations with RF positivity and with the risk of RA. METHODS: Coffee consumption was studied, firstly, for its association with RF (sensitised sheep cell agglutination titre >/=128) in a cross sectional survey of 6809 subjects with no clinical arthritis, and secondly, for its prediction of RA in a cohort of 18 981 men and women who had neither arthritis nor a history of it at the baseline examination in 1973-76. Up to late 1989, 126 subjects of the cohort study had developed RA, of whom, 89 were positive for RF by the time of diagnosis. RESULTS: In the cross sectional survey the number of cups of coffee drunk daily was directly proportional to the prevalence of RF positivity. Adjusted for age and sex this association was significant (p value for linear trend, 0.008), but after further adjustment for smoking the linear trend declined below significance (p=0.06). In the cohort study there was an association between coffee consumption and the risk of RF positive RA that was not due to age, sex, level of education, smoking, alcohol intake, body mass index, or serum cholesterol. After adjustment for these potential confounders the users of four or more cups a day still had a relative risk of 2.20 (95% confidence interval 1.13 to 4.27) for developing RF positive RA compared with those drinking less. Coffee consumption did not predict the development of RF negative RA. CONCLUSION: Coffee consumption may be a risk factor for RA, possibly through mechanisms contributing to the production of RF. This hypothesis remains to be tested in further studies. (+info)
The effect of unfiltered coffee on potential biomarkers for colonic cancer risk in healthy volunteers: a randomized trial.
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BACKGROUND: Epidemiologic studies suggest that coffee use might protect against colorectal cancer. Inconsistencies as to the effect of coffee use and colorectal cancer between epidemiologic studies might be related to the type of coffee brew. OBJECTIVE: We studied the effect of unfiltered coffee consumption on putative biomarkers for colonic cancer risk. DESIGN: A total of 64 healthy volunteers (31 men and 33 women), with a mean age of 43 +/- 11 years were randomly assigned to two groups in a crossover design, with two intervention periods of 2 weeks separated by a washout period of 8 weeks. Treatments were 1 L of cafetiere (French press) coffee daily or no coffee. At the end of each intervention period, fasting blood samples, colorectal biopsies and 48 h faeces were collected. RESULTS: No effect of coffee on colorectal cell proliferation, assayed by estimating the Proliferating Cell Nuclear Antigen labelling index, was seen. Additionally, no effects were seen on the concentrations of faecal soluble bile acids and colorectal mucosal glutathione S-transferase activity. However, unfiltered coffee significantly increased the glutathione content in the colorectal mucosa by 8% and in plasma by 15%. Other aminothiols in plasma also increased on coffee. CONCLUSION: Unfiltered coffee does not influence the colorectal mucosal proliferation rate, but might increase the detoxification capacity and anti-mutagenic properties in the colorectal mucosa through an increase in glutathione concentration. Whether this effect indeed contributes to a lower colon cancer risk remains to be established. (+info)
Heavy coffee consumption and plasma homocysteine: a randomized controlled trial in healthy volunteers.
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BACKGROUND: An elevated plasma concentration of total homocysteine is considered to be a strong risk factor for cardiovascular disease. Heavy coffee drinking has been related to high homocysteine concentrations in epidemiologic studies and in one experiment in which healthy subjects drank unfiltered, boiled coffee. OBJECTIVE: Our goal was to determine whether daily consumption of paper-filtered coffee raises plasma concentrations of total homocysteine in healthy subjects. DESIGN: Twenty-six volunteers (18-53 y of age) consumed 1 L/d of paper-filtered coffee brewed with 70 g regular ground beans or no coffee for 4 wk each in a randomized, crossover design. RESULTS: The mean (+/-SD) plasma concentration of total homocysteine in fasting blood was 8.1 +/- 1.8 micromol/L after abstention from coffee and 9.6 +/- 2.9 micromol/L after 3-4 wk of coffee drinking, a difference of 1.5 micromol/L (95% CI: 0.9, 2.1 micromol/L) or 18% (P: < 0.001). Coffee increased homocysteine concentrations in 24 of 26 individuals. Circulating concentrations of vitamin B-6, vitamin B-12, and folate were unaffected. CONCLUSION: Drinking large quantities of paper-filtered coffee raises fasting plasma concentrations of total homocysteine in healthy individuals. (+info)