Search PubMed⌕ Search

Biomedical subjects

Michael Bursztyn

Publications and source records attributed to Michael Bursztyn.

33 records · Page 2Linked to original sources
PubMed2005

The siesta and mortality: twelve years of prospective observations in 70-year-olds.

STUDY OBJECTIVE: To examine effect of siesta on mortality. DESIGN: A 12 years prospective cohort. SETTING: Population sample. PARTICIPANTS: Residents of Jerusalem (n=455), 70 year olds. INTERVENTIONS: N/A. RESULTS: There were more males in the group with the siesta (n=276), 68% and more (16%) past myocardial infarction than those without the siesta, 6% (n=179) p < 0.01. After 12 years 147 subjects died. Survival was 64% in people practicing the siesta, and 74%, who did not p = 0.005. In a Cox proportional hazard model, that included many confounding factors hazard ratio (HR) for mortality was 1.6 95% confidence interval (CI) 1.2-2.7, for those who napped. After exclusion of the 19 subjects who died during the first 2 years of follow-up, the hazard ratio was not materially altered, HR of 1.6 95% CI, 1.0-2.6. CONCLUSION: Although causality is not clear, the siesta appears to be a significantly independent mortality predictor.

Aged↗
PubMed2004

Pulse pressure is more susceptible to the white coat effect than is systolic blood pressure: observations from real-life ambulatory blood pressure monitoring.

BACKGROUND: Pulse pressure is a derivative of arterial stiffness. We have previously demonstrated ambulatory pulse pressure to be relatively independent from the blood pressure (BP) lowering during sleep, and thus of a neurogenic effect. On the other hand, white coat BP effects are thought to involve neurogenic activation. The aim of this work was to analyze white coat induced variability in pulse pressure. METHODS: Percent clinic-awake differences in systolic BP (SBP) and pulse pressure (white coat effects) were calculated for 688 consecutive subjects (mean age 60 +/- 16 years, 58% female). Of the subjects, 23% had controlled hypertension, 45% uncontrolled hypertension, 8% normotension, and 4% isolated office hypertension; all were referred to our unit for 24 h ambulatory BP monitoring. RESULTS: Pulse pressure highly correlated with SBP (r = 0.82, P <.00001). We found a larger white coat effect on pulse pressure than on SBP (8.3% and 5.2%, respectively, P < or =.0001). This was true in all subgroups except in normotensive subjects. Specifically, the magnitude of the white coat effect on pulse pressure was greater than on SBP in subjects with treated hypertension, untreated hypertension, and isolated office hypertension, and in young hypertensive subjects, older subjects, and those with diabetes. CONCLUSIONS: Although pulse pressure is related to the mechanical properties of large arteries, it is also influenced by the white coat effect, a neurogenic process. Furthermore, in hypertensive but not in normotensive subjects, the white coat effect on pulse pressure is significantly more pronounced than on SBP.

Adult↗
PubMed2004

Is prolonged immobilization a risk factor for symptomatic venous thromboembolism in elderly bedridden patients? Results of a historical-cohort study.

Prolonged immobilization and advanced age are considered to be important risk factors for venous thromboembolism (VTE). Nevertheless, the need for VTE prophylaxis in long-term bedridden patients is not known. To assess whether very prolonged immobilization (i.e. over three months) carries an increased risk for clinically apparent VTE, we performed a historical-cohort study of nursing home residents during a ten-year period. Data concerning patient's mobility and incidence of overt deep vein thrombosis or pulmonary embolism were registered. The mean resident age was 85+/-8.4 years. Eighteen mobile and eight immobile patients were diagnosed with clinically significant thromboembolic events, during 1137 and 573 patient-years of follow up, respectively. The incidence of venous thromboembolic events was similar in both chronically immobilized and mobile patient groups, 13.9 and 15.8 per thousand patient years, respectively (p=0.77). The rate ratio for having a VTE event in the immobilized patient group as compared with the mobile group was 0.88 (95% Confidence Interval (CI) 0.33 to 2.13). When taking into account baseline characteristics, risk factors and death rates by various causes, no differences were found between the two groups. In conclusion, chronically immobile bedridden patients are no more prone to clinically overt venous thromboembolic events than institutionalized mobile patients. Until further studies are performed concerning the impact of very prolonged immobilization on the risk of VTE, there is no evidence to support primary prevention after the first three months of immobilization. Evidence for efficacy or cost effectiveness beyond this early period is not available.

Aged↗
PubMed2003

Sex differences in the effect of heart rate on mortality in the elderly.

OBJECTIVES: To examine the association between heart rate and mortality risk in the elderly. DESIGN: Longitudinal cohort. SETTING: Outpatient. PARTICIPANTS: Four hundred twenty-two people, aged 70 upon entry, were surveyed and followed for 6 years. MEASUREMENTS: Pulse rate was measured manually, while sitting and standing, and heart rate was measured from electrocardiogram recordings. The population was divided into quartiles of heart rate, with the top quartile comprising those with heart rate greater than 77 beats per minute (bpm) and the bottom quartile those with heart rate less than 60 bpm. RESULTS: After controlling for possible confounders, there was a clear correlation (r) between heart rate and all-cause mortality in elderly women (r=0.25, P=.0003). The correlation in women was observed using the three different methods for measuring heart rate. Heart rate was associated with all-cause and cardiovascular mortality. There was no relationship between heart rate and level of exercise or smoking status. In multiple regression analysis, the increased risk of death in the women was independent of previous cardiovascular or cerebrovascular disease, hypertension, anemia, congestive heart failure, smoking, and level of exercise or activities of daily living (relative odds ratio (ROR)=3.37, 95% confidence interval (CI)=0.96-11.8). When women using beta-blockers were excluded, this relationship became even stronger (ROR=8.5, 95% CI=1.19-60.1). CONCLUSION: Elevated heart rate is related to increased mortality in elderly women, thus representing a simple index of general health status in this population. Elevated heart rate did not predict mortality in elderly men.

Activities of Daily Living↗
PubMed2003

Insulin-induced hypertension, L-arginine, and endothelial nitric oxide synthase in pregnant rats.

Pregnancy-induced hypertension in rats with chronic exogenous hyperinsulinemia is associated with reduced urinary excretion of nitric oxide metabolites. We tested the hypothesis that there are perturbations of endothelial nitric oxide synthase in their kidneys. We studied three groups of rats: control pregnant rats (n = 6); pregnant rats with hyperinsulinemia by subcutaneous sustained-release insulin pellet (n = 5); and hyperinsulinemic pregnant rats treated with l-arginine 2 gL in drinking water (n = 5). By the end of pregnancy blood pressure was 78 +/- 12 mm Hg in controls, 119 +/- 15 mm Hg in hyperinsulinemic rats, and 77 +/- 8 mm Hg in l-arginine-treated hyperinsulinemic rats, p < 0.007. Serum creatinine was 0.4 mg/dl in controls, 0.6 mg/dl in hyperinsulinemic rats, and 0.5 mg/dl in l-arginine-treated rats, p < 0.05. Corresponding urinary excretion of nitric oxide metabolites was 2.1 +/- 0.5, 1.2 +/- 0.2, and 1.5 +/- 0.2 micromols/mg creatinine, p < 0.01. Expression of endothelial nitric oxide synthase protein in kidneys by Western blot was not different between controls and hyperinsulinemic rats, 5.6 +/- 2.4 and 5.8 +/- 3.4 OD x mm2, but was nearly doubled in l-arginine-treated rats, 10.8 +/- 2.3, p < 0.03. Thus, the salutary effect of l-arginine on hyperinsulinemic pregnancy-induced hypertension (PIH) may be mediated, in part, by endothelial nitric oxide synthase in their kidneys.

Amino Acids, Essential↗
PubMed2003

Ambulatory pulse pressure is a relatively sleep-independent variable.

OBJECTIVES: Characterization of sleep-induced pulse and mean arterial pressure (MAP) dip. DESIGN: Prospective study of consecutive referred patients. SETTING: Hypertension unit of community university hospital. PARTICIPANTS: A total of 500 consecutive subjects referred to our unit for ambulatory blood pressure (BP) monitoring. There were 200 men and 300 women, the majority of which were treated hypertensives. Mean age was 59.7 +/- 16.6 years. MAIN OUTCOME MEASURES: Effect of sleep on MAP and pulse pressure (PP). RESULTS: Twenty-four hour MAP was 98 +/- 10 mmHg. Awake and asleep MAPs were 101 +/- 11 and 87 +/- 11 mmHg, respectively. Twenty-four hour, awake and asleep pulse pressures were 60 +/- 13, 61 +/- 13 and 58 +/- 13 mmHg, respectively. MAP dip was 14%, 95% confidence interval (CI) 13.4-14.6, whereas PP dip was 5%, 95% CI 4.1-5.8. Thus, the MAP dip was almost three times the PP dip (P < 0.0001). This held true for normotensives, hypertensives (treated and untreated), men, women and diabetic subjects. CONCLUSIONS: Although pulse pressure is derived from BP, it is more stable during a 24-h period, with a lesser effect of sleep compared with MAP. This more rigid nature of the PP could explain its better prognostic value, compared to that of MAP.

Adult↗
PubMed2003

Accelerated coronary artery calcification in mildly reduced renal function of high-risk hypertensives: a 3-year prospective observation.

OBJECTIVE: To examine the effect of mild renal dysfunction on coronary artery calcifications. METHODS: We examined the progression of coronary atherosclerosis, as measured by dual-section spiral computed tomography, using the total coronary artery calcium score as a quantitative measure of the burden of atherosclerosis. Of 547 high-risk Israeli hypertensive patients, who were participants of the prospective calcification study (a side-arm of the international INSIGHT study), 313 patients completed the 3-year follow-up. Subjects were studied upon entry (on placebo) and again after 3 years of treatment (nifedipine or thiazide). Patients were divided into two groups depending on their creatinine clearance: (i) </= 60 ml/min, renal dysfunction (RD) (n = 53) and (ii) > 60 ml/min, normal renal function group (n = 263). RESULTS: Blood pressure, hypercholesterolemia, and smoking did not differ between the groups. After 3 years of treatment, blood pressure control was similar, whereas the total coronary artery calcium score progression was two-fold greater in the RD than the normal group (156 +/- 32 versus 64 +/- 8, respectively) (P = 0.006). In a multiple logistic regression analysis, the odds ratio (OR) for total coronary artery calcium score progression was higher for the RD group (2.1) [95% confidence interval (CI) 1.2-3.7]. Gender, body mass index, smoking, cholesterol, family history of ischaemic heart disease and diabetes were not significant predictors. Thiazide-based antihypertensive therapy predicted a faster progression compared to nifedipine (OR 1.66, 95% CI 1.09-2.51). CONCLUSIONS: Mild renal dysfunction accelerates coronary artery calcifications, above and beyond conventional risk factors.

Aged↗
PubMed2002

The siesta and mortality in the elderly: effect of rest without sleep and daytime sleep duration.

STUDY OBJECTIVE: To examine the effects of daytime rest without sleep and duration of the siesta on mortality. DESIGN: Longitudinal observation. SETTING AND PARTICIPANTS: Population sample of 442 community-dwelling 70-year-old subjects examined both at home and in a geriatric hospital. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Overall mortality for those who neither rested nor slept was 9.3%, for those who rested without sleep 10.9%, and for those who slept 19%, p<0.02. Males had higher mortality (19%) than females (10%), p<0.006. Rest without sleep had no effect on mortality: in males, 13%, 21%, 18% for no rest, rest of less than one hour, or more than one hour with respective 8%, 6% and 4% in females. However, daytime sleep in males of more than one hour had 28.2% mortality, whereas sleep of one hour or less had 13.6% mortality, p=0.02. In females mortality rate was not different by sleep duration: 16% and 13.6% for those who slept for one hour or less, or more than one hour, respectively. In a multivariate analysis in females, a siesta of one hour or less was associated with risk odds ratio (ROR) of 4.67 and 95% confidence interval (CI) 1.22-17.80 and of one to two hours, ROR was 5.57 and 95% CI 1.05-29.49. For males, siesta of less than one hour was not associated with excess risk, ROR 0.9 and 95% CI 0.39-2.38; a siesta of one to two hours with ROR of 2.61 and 95% CI 1.01-6.80; and two hours or more ROR 13.6 and 95% CI 0.98-2.10. CONCLUSIONS: Rest without sleep is not associated with excess risk of mortality. However, siesta of one to two hours is associated with increased mortality in males whereas, in women, a siesta of less than one hours confers the excess risk.

Aged↗