Relationships among biomarkers of one-carbon metabolism.

One-carbon metabolism is a network of metabolic pathways, disruption of which has been associated with cancer and other pathological conditions. Biomarkers of these pathways include homocysteine (HCY), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH). A better understanding of the relationships between these biomarkers is needed for their utilization in research. This study investigated the relationships between fasting concentrations of plasma HCY, SAM, SAH and the ratio of SAM:SAH, and serum folate, vitamin B(12) and creatinine in a healthy adult population. A cross-sectional study recruited 678 volunteers; only subjects with complete data (n = 581) were included in this analysis. Correlations were used to examine bivariate relationships among the biomarkers and multivariate linear regression determined independent relationships with HCY, SAM and SAH treated as dependent variables in separate models. Multivariate logistic regression examined determinants of a low SAM:SAH ratio (defined as having a SAM:SAH ratio in the bottom quartile and SAH value in the top quartile). HCY correlated inversely with folate and vitamin B(12) and weakly correlated with SAH and creatinine. Both SAM and SAH correlated with creatinine but were independent of serum folate and vitamin B(12). In multivariate analyses, folate, vitamin B(12), creatinine, sex and age were associated with HCY; age and creatinine were determinants of SAM, and sex and creatinine determinants of SAH. Finally, male sex and increasing creatinine levels were associated with having a low SAM:SAH ratio. Findings suggest that HCY, SAM and SAH are relatively independent parameters and reflect distinct aspects of one-carbon metabolism.

Randomised equivalence trial comparing three month and six month follow up of patients with hypertension by family practitioners.

OBJECTIVE: To compare blood pressure control, satisfaction, and adherence to drug treatment in patients with treated hypertension followed up by their family physicians either every three months or every six months for three years. DESIGN: Randomised equivalence clinical trial. Settings 50 family practices in south eastern Ontario, Canada. PARTICIPANTS: 609 patients aged 30-74 years with essential hypertension receiving drug treatment whose hypertension had been controlled for at least three months before entry into the study. RESULTS: 302 patients were randomly assigned to follow up every three months and 307 to follow up every six months. Baseline variables in the two groups were similar. As expected, patients in the six month group had significantly fewer visits, but patients in both groups visited their doctor more frequently than their assigned interval. Mean blood pressure was similar in the groups, as was control of hypertension. Patient satisfaction and adherence to treatment were similar in the groups. About 20% of patients in each group had blood pressures that were out of control during the study. CONCLUSIONS: Follow up of patients with treated essential hypertension every six months is equivalent to follow up every three months. Patient satisfaction and adherence to treatment are the same for these follow up intervals. As about 20% of patients' hypertension was out of control at any time during the study in both groups, the frequency of follow up may not the most important factor in the control of patients' hypertension by family practitioners.

Lack of association between activity or fitness and loss of control of hypertension.

BACKGROUND: Many treated hypertensive patients have inadequate control of their blood pressure. Physical activity and cardiorespiratory fitness are important in the development and treatment of hypertension. Less is known about their relationships with hypertension control in the context of long-term management. OBJECTIVES: To identify whether patients with lower levels of activity or fitness are at risk for loss of control of hypertension. METHODS: Follow-up blood pressure measurements were recorded over the period of a year in a cohort of initially controlled hypertensive patients, under the care of 50 family physicians in a variety of practice settings. A questionnaire for a one-year recall of leisure time physical activity and the Step Test, an indirect measure of maximal oxygen consumption, were administered to the patients at the end of the period of blood pressure observations. The study group for the activity questionnaire consisted of 385 patients; 310 of whom undertook the fitness test. Sociodemographic, clinical and lifestyle factors were analyzed as potential confounders in the relationships of main interest in this study: between activity and fitness, respectively, with loss of control of hypertension. RESULTS: Sixteen per cent of patients (95% CI 12, 20) had an increase of 20 mmHg systolic or 10 mmHg diastolic from baseline to the average of three follow-up blood pressures, and 14% (95% CI 11, 18) had blood pressures above the entry thresholds on at least two of three follow-up visits. No associations were found between loss of control of hypertension and physical activity or cardiorespiratory fitness. CONCLUSIONS: Lower levels of physical activity and fitness are not associated with loss of hypertension control. The identification of patients at risk for loss of hypertension control, which could be useful in targeting selected groups for increased follow-up and in understanding the high prevalence of uncontrolled hypertension, requires further study.