Familial correlations, segregation analysis, and nongenetic correlates of soy isoflavone-metabolizing phenotypes

Particular intestinal bacteria metabolize the soy isoflavone daidzein to equol and O-desmethylangolensin (O-DMA), metabolites that can be identified in urine. Individuals that harbor bacteria capable of producing equol or O-DMA are known as equol producers (approximately 30%-50% of the population) and O-DMA producers (approximately 80%-90% of the population), respectively. The equol-producer phenotype has been associated with sex hormone-related outcomes in several studies. However, the bacteria responsible for these phenotypes have not yet been identified and factors that influence the manifestation of these phenotypes are not well understood. To evaluate familial clustering of and nongenetic factors associated with these phenotypes, 410 individuals from 112 families participated in phenotyping (3-day soy challenge and Day 4 spot urine collection). In segregation analyses of the equol-producer phenotype, the Mendelian dominant model provided the most parsimonious fit to the data, suggesting that the pattern of inheritance of the equol-producer phenotype is consistent with an autosomal dominant trait. This phenotype was positively associated with education (p trend = 0.01), but not with sex, smoking, or several dietary factors. Results of the segregation analyses of the O-DMA-producer phenotype were inconclusive; no other models provided a more parsimonious fit to the data than the general model. This phenotype was inversely associated with age in a nonlinear model (p = 0.01), positively associated with age- and sex-adjusted height (odds ratio [OR] 10-cm increase = 0.38, 95% confidence interval [CI] = 0.15, 0.95) and body mass index (kg/m(2)) (OR = 0.91, 95% CI = 0.85, 0.96), but not with sex, education, smoking, or several dietary factors. These results suggest the equol-producer phenotype may be under some degree of genetic control and that there are likely other environmental factors not evaluated in the present analysis that contribute to both of these phenotypes. These results provide a foundation for further work to refine our understanding of heritable and environmental determinants of daidzein-metabolizing phenotypes.

Adrenaline infusion evokes increased thromboxane B2 production by platelets in healthy men: the effect of beta-adrenoceptor blockade

The effects of direct adrenergic stimulation, achieved by 60-min adrenaline infusion (0.1-0.2 microgram kg-1 min-1), on thromboxane B2 (TxB2) production by platelets in whole blood ex vivo and on ADP-induced platelet aggregation were studied in seven healthy male volunteers. The effects of two beta-adrenergic blocking agents, pindolol and practolol, on the adrenaline-induced changes were furthermore analyzed. Adrenaline administration resulted in an about ten-fold elevation in plasma adrenaline, and an about three-fold increase in TxB2 production by platelets at 30 min of infusion. The increased TxB2 production persisted throughout the entire adrenaline infusion, and up to 30 min of postinfusion period (recovery). Pindolol blunted markedly the effects of adrenaline on platelet TxB2 production, whereas practolol seemed to have only a weak effect. The sensitivity of platelets to ADP-induced aggregation did not change during the 60 min of adrenaline infusion. However, at 60 min of recovery the platelets showed a significantly increased sensitivity to ADP. Correspondingly, pindolol treatment did not affect platelet sensitivity during the infusion period, but at 60 min of recovery it had caused a significantly decreased sensitivity of platelets to ADP-stimulation. Plasma-free fatty acids increased markedly during the adrenaline infusion. This increase was totally blocked by pindolol, but only partly by practolol. The present results demonstrate that adrenaline, at plasma levels seen for example, in complicated myocardial infarction, stimulates platelet TxB2 production and increases the sensitivity of platelets to ADP after the infusion. Pindolol, but not practolol, inhibits these adrenaline-induced changes in platelet behaviour.