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Biomedical subjects

A G Bostom

Publications and source records attributed to A G Bostom.

66 records · Page 4Linked to original sources
PubMed1994

High dose ascorbate supplementation fails to affect plasma homocyst(e)ine levels in patients with coronary heart disease.

Pharmacologic doses of folate, in the absence of clinical folate deficiency, can reduce plasma levels of the putatively atherothrombotic amino acid, homocysteine (H(e)). Data suggesting that H(e) may accumulate in experimental scurvy prompted us to explore the efficacy of high dose ascorbate supplementation as a H(e)-lowering treatment, in the absence of clinical ascorbate deficiency. A randomized, placebo-controlled trial of 12 weeks of high dose (4.5 g/day) ascorbate supplementation was completed by 44 patients with established coronary heart disease. No significant change in mean fasting total plasma H(e) levels was demonstrable despite a marked increase in mean fasting plasma ascorbate levels amongst those patients randomized to active treatment. Ascorbate supplementation to prevent the development of fasting hyperhomocysteinemia may only be relevant at scorbutic levels of plasma ascorbate.

Ascorbic Acid↗
PubMed1994

A prospective investigation of elevated lipoprotein (a) detected by electrophoresis and cardiovascular disease in women. The Framingham Heart Study.

BACKGROUND: Sinking prebeta lipoprotein is a putative marker for elevated levels of lipoprotein (a). Although prospective data suggest that increased plasma lipoprotein (a) is an independent risk factor for coronary heart disease in men, no prospective studies are available in women. METHODS AND RESULTS: From 1968 through 1975, sinking prebeta lipoprotein was determined by paper electrophoresis in 3103 women Framingham Heart Study participants who were free of prevalent cardiovascular disease. A sinking prebeta lipoprotein band was detectable in 434 of the women (14%) studied. The median follow-up interval was approximately 12 years. Incident cardiovascular disease was associated with band presence using a proportional hazards model that included age, smoking, body mass index, systolic blood pressure, glucose intolerance, low- and high-density lipoprotein cholesterol, and ECG left ventricular hypertrophy. Multivariable adjusted relative risk estimates (with 95% confidence intervals) for outcomes in the band present versus absent groups were as follows: myocardial infarction (82 events), 2.37 (1.48 to 3.81); intermittent claudication (62 events), 1.94 (1.07 to 3.50); cerebrovascular disease (83 events), 1.88 (1.12 to 3.15); total coronary heart disease (174 events), 1.61 (1.13 to 2.29); and total cardiovascular disease (305 events), 1.44 (1.09 to 1.91). A subset analysis indicated that band presence was 50.9% sensitive and 95.4% specific for detecting plasma lipoprotein (a) levels of > 30 mg/dL, the threshold value linked to increased cardiovascular disease risk in men. CONCLUSIONS: Sinking prebeta lipoprotein was a valid surrogate for elevated lipoprotein (a) levels in Framingham Heart Study women. Band presence and, equivalently, elevated plasma lipoprotein (a), was a strong, independent predictor of myocardial infarction, intermittent claudication, and cerebrovascular disease. Confirmation of these findings in other longitudinal studies of women is needed.

Adult↗
PubMed1991

Lipid and lipoprotein profiles relate to peak aerobic power in spinal cord injured men.

The relationship between peak VO2 and serum lipids, lipoproteins, and apolipoproteins was assessed in nine traumatic spinal cord injured (SCI), active, male volunteers. Mean (SD) age, height, and weight were 30.6 (11.6) yr, 171.1 (11.3) cm, and 74.2 (12.5) kg, respectively. Peak VO2 (X = 2.13 l.min-1) was assessed by a graded arm-crank test to maximum, percent body fat (X = 28.7%) by densitometry, and lipid profile by measures of serum triglycerides, total cholesterol (TC), high and low density lipoprotein cholesterol (HDL-C and LDL-C, respectively), apolipoproteins (apoA-1, apoB), and various ratios of lipids, lipoproteins, and apolipoproteins. Significant inverse relationships emerged between peak VO2 and TC/HDL-C (r = -0.86; P less than 0.01), apoB/apoA-1 (r = -0.75; P less than 0.05), triglycerides (r = -0.73; P less than 0.05), and LDL-C/HDL-C (r = -0.72; P less than 0.05). Direct correlations (P less than 0.05) were demonstrated between peak VO2 and apoA-1/apoB (r = 0.71) and HDL-C/apoA-1 (r = 0.64). The present results indicate that, for active, mid-to-lower thoracic SCI men, the putative atherogenic and antiatherogenic lipid, lipoprotein, and apolipoprotein indices are significantly related to peak VO2 in a manner similar to that described for the able-bodied. These findings indicate the relevance of aerobic fitness assessment in planning CHD prevention strategies for the SCI.

Adult↗
PubMed1987

Ergometer modification for combined arm-leg use by lower extremity amputees in cardiovascular testing and training.

A commercial arm-leg ergometer was adapted so that combined bilateral arm-single leg work could be performed by unilateral lower extremity amputees from their own wheelchairs. Three middle-aged to elderly unilateral amputees performed progressive discontinuous bilateral arm crank and combined bilateral arm-single leg cycle exercise tests on the same air-braked ergometer adapted for either form of ergometry. Select amputees may achieve greater peak oxygen uptakes (VO2), power outputs (PO), and heart rates (HR) during combined bilateral arm-single leg cycle testing versus bilateral arm crank testing. Following 14 weeks of combined arm-leg training on the modified ergometer, a 73-year-old above-knee amputee demonstrated peak VO2 and PO increases of 25% (+3.8 mL X kg-1 X min-1) and 33% (+25W) respectively. Combined arm-leg ergometry as described herein may activate the largest available muscle mass and elicit the greatest oxygen uptake during exercise testing. In addition this exercise modality may simultaneously condition the arms and leg, providing functional gains in both wheelchair propulsion and prosthetic ambulation.

Amputees↗
PubMedDate not supplied

Residual renal function in a large cohort of peritoneal dialysis patients: change over time, impact on mortality and nutrition.

OBJECTIVE: Residual renal function contributes importantly to total solute clearance in peritoneal dialysis (PD) patients. This study was designed to examine the progression of residual renal function over time and its impact on nutrition and mortality in PD patients in the six New England states (ME, NH, VT, CT, MA, RI) comprising End Stage Renal Disease (ESRD) Network 1. DESIGN: As part of the ESRD Clinical Indicators Project, data on 990 PD patients in Network 1 were abstracted from data supplied by dialysis units in the fourth quarter of 1997. This included demographic information; dose of PD in L/day; weekly renal, dialysis, and total Kt/V urea; weekly renal, dialysis, and total creatinine clearance (CCr); serum albumin level; and mortality and transplantation information. Data collection was repeated in the second and fourth quarters of 1998 and in the second quarter of 1999. PATIENTS: 990 PD patients in Network 1. OUTCOME MEASURES: The change in total and renal solute clearances over time, the relationship between renal clearance and mortality, and the relationship between renal clearance and nutritional status, as represented by serum albumin. RESULTS: Over the 2-year period, mean weekly renal Kt/V urea and weekly renal CCr dropped significantly. To examine the effect of residual renal function on mortality, patients were divided into high and low (above and below the median) weekly renal Kt/V urea and weekly renal CCr groups. Patients above the median levels of both weekly renal Kt/V urea and weekly renal CCr had a significantly decreased risk of dying during the observation period, after controlling for age, gender, serum albumin level, and diabetic status [OR for high vs low renal Kt/V urea 0.54 (CI 0.34 - 0.84), OR for high vs low renal CCr 0.61 (CI 0.40 - 0.94)]. The mean weekly renal Kt/V urea was significantly and directly correlated with the mean serum albumin level by Spearman rank correlation (R = 0.133, p < 0.001), as was the mean weekly renal CCr (R = 0.115, p < 0.001). CONCLUSIONS: Residual renal function is an important contributor to total solute clearance in PD patients. Even at low levels it is linked to decreased mortality and better nutritional status.

Adolescent↗
PubMedDate not supplied

The effect of high-dose ascorbate supplementation on plasma lipoprotein(a) levels in patients with premature coronary heart disease.

STUDY OBJECTIVE: To determine the efficacy of high-dose ascorbate supplementation in lowering lipoprotein(a) [Lp(a)] levels in patients with premature coronary heart disease (CHD). DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Outpatient clinic. PATIENTS: Forty-four patients with documented premature CHD, defined as confirmed myocardial infarction and/or angiographically determined stenosis of 50% or greater in at least one major coronary artery before age 60 years. INTERVENTIONS: Patients were block randomized on the basis of age, gender, and screening Lp(a) concentrations to receive ascorbate 4.5 g/day or placebo for 12 weeks. MEASUREMENTS AND MAIN RESULTS: High-dose ascorbate was well tolerated and produced a marked elevation in mean plasma ascorbate levels (+1.2 mg/dl; p < 0.001). Multiple linear regression analysis revealed no significant effect of supplementation on postintervention Lp(a) levels (p = 0.39) in a model that included treatment group assignment, and baseline Lp(a) levels. CONCLUSIONS: Our findings do not support a clinically important lowering effect of high-dose ascorbate on plasma Lp(a) in patients with premature CHD.

Ascorbic Acid↗
PubMedDate not supplied

Family history and premature coronary heart disease.

BACKGROUND: We were interested in studying whether a family history of coronary heart disease (CHD) persisted as a significant risk factor for premature coronary heart disease after adjusting for traditional and nontraditional risk factors. METHODS: Ninety-five case patients with documented premature CHD (occurring in a person less than 60 years old and with greater than 50 percent occlusion of a major epicardial vessel or a documented myocardial infarction) and 95 community-based control patients were examined for risk factors including family history, hypertension, diabetes mellitus, sedentary lifestyle, smoking, body mass index, total cholesterol, high-density lipoprotein cholesterol, triglycerides, low-density lipoprotein cholesterol, lipoprotein(a), homocysteine, and fibrinogen. RESULTS: The risk of premature CHD for a positive family history ranged from an odds ratio (OR) of 3.25 for a standard family history of CHD in a first-degree relative, 5.9 for family history of early CHD in a first-degree relative before the age of 45 years, and 6.1 for a strong family history of CHD defined as CHD in at least two first-degree relatives. Family history persisted as a significant risk factor for premature CHD (OR = 3.9, 95 percent confidence interval [CI] 1.8-8.7) in multiple variable models that included traditional and nontraditional risk factors. It was rare, however, for a person with a positive family history not to have at least two other traditional or nontraditional risk factors. CONCLUSIONS: Family history of CHD should not be considered a simple binary risk factor for premature CHD, and a positive family history of CHD indicates that a person is at high risk for premature CHD independent of traditional and nontraditional risk factors.

Bias↗