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Biomedical subjects

D A Leaf

Publications and source records attributed to D A Leaf.

30 records · Page 2Linked to original sources
PubMed1990

Gender differences in coronary angiographic findings from 1972 through 1981 in Los Angeles, California.

The angiographic findings of 930 men and 257 women who were referred to a Los Angeles County hospital from 1972 through 1981 are compared. Chi square test results indicated triple-vessel disease was more common in men (37.1%) compared with women (18.7%). The prevalence of normal angiographic findings was higher in women (23.3%) than in men (8.1%). However, for men and women with evidence of coronary artery disease, virtually identical percentages of subjects had left main, single-, double-, and triple-vessel disease. Although the incidence of coronary artery disease decreased during this time for the Los Angeles population as a whole, no differences in patterns of coronary vessel lesions were evidenced.

Coronary Disease↗
PubMed1990

Overweight: assessment and management issues.

Obesity is associated with an increased risk of coronary artery disease, hypertension, diabetes, hypercholesterolemia, cancer and other conditions. Although generalized obesity is associated with increased risk, the android pattern of body fat distribution may be a more sensitive predictor of coronary artery disease. A gradual weight reduction program, including adherence to a low-fat, calorie-restricted diet and participation in daily exercise, is the best approach to reduce weight and body fat.

Diet, Reducing↗
PubMed1989

The hypolipidemic effects of gemfibrozil in type V hyperlipidemia. A double-blind, crossover study.

Thirteen patients with phenotypic type V hyperlipidemia were treated with either gemfibrozil (Lopid) or a placebo in a randomized, double-blind, crossover study for two 8-week periods. A 4-week baseline period of a low-fat diet preceded the study and served as a dietary control period. A 4-week washout period followed the two 8-week periods. Compared with the placebo phase, gemfibrozil produced a significant reduction in the concentrations of total plasma triglycerides (21.03 vs 5.50 mmol/L) and very low-density lipoprotein triglycerides (14.40 vs 4.59 mmol/L) as well as in total plasma cholesterol levels (10.88 vs 5.62 mmol/L) and very low-density lipoprotein cholesterol (6.66 vs 2.15 mmol/L). Chylomicronemia was virtually abolished by the drug treatment. As expected in treated patients with type V hyperlipidemia, concentrations of low-density lipoprotein cholesterol rose after therapy with gemfibrozil (3.08 mmol/L) as compared with placebo (1.84 mmol/L); high-density lipoprotein cholesterol also increased (0.85 mmol/L after therapy with gemfibrozil, 0.62 mmol/L after placebo). The previously very low values for both of these lipoproteins increased at the same time that the total plasma cholesterol value decreased. We conclude that gemfibrozil is a well-tolerated and effective hypolipidemic agent for the treatment of patients with severe hypertriglyceridemia when used in conjunction with a low-fat diet.

Adult↗
PubMed1989

Omega-3 fatty acids and coronary artery disease. More than a fish tale.

The use of omega-3 fatty acids to reduce the risks of coronary artery disease is appealing because this product occurs naturally in fish oil. Many questions remain to be answered conclusively, however, including how much omega-3 fatty acid is needed to provide this theoretical protective effect. Suitable trials to determine whether commercially marketed fish oil capsules are of benefit to the general population have not been done. However, increased consumption of seafood seems appropriate even without definitive evidence of its benefits.

Coronary Disease↗
PubMed1988

Triglycerides. Are they important?

The importance of lowering plasma cholesterol is well documented, but hypertriglyceridemia should not be ignored. Effective management requires proper measurement of plasma triglyceride levels and assessment of underlying causes. Conveniently, the same principles used in management of hypercholesterolemia can be applied to hypertriglyceridemia, and patients should be counseled regarding appropriate dietary measures. If these fail, medication may be necessary.

Adult↗
PubMed1988

A woman's heart. An update of coronary artery disease risk in women.

Coronary artery disease accounts for a third of all deaths in women. Traditionally, studies on this disease have been conducted with male subjects. A growing body of evidence indicates that oral contraceptive and postmenopausal estrogen use present risk factors for the disease that are unique to women. In addition, sex differences exist with regard to the relationship of most of these risk factors to the development of the disease. An understanding of these differences has an important role in expanding the management of coronary artery disease risk reduction for women and in defining directions for future research.

Adolescent↗
PubMed1985

Fitness: a new look at an old term (measurements of human aerobic performance).

Despite the increased public interest in being fit, there is no universally accepted definition of "fitness." Various reports equate fitness to oxygen consumption with exercise. This genetically determined V02 maximum is the limiting factor in high-intensity, short duration maximal aerobic exercise. For the nonathelete, however, this capacity may not be an accurate assessment of fitness. Instead, the ability of this individual to do less vigorous work of greater duration may be the best estimate of his fitness. Energy expenditure, a requirement of work, is obtained from the metabolism of carbohydrates and lipids. A measure of the relative utilization of these substrates is the respiratory quotient (R.Q.). Initial phases of exercise depend primarily on carbohydrate metabolism which is reflected by an RQ of 1.0. As exercise continues, substrate utilization relies upon an increasing percentage of free fatty acid metabolism and the R.Q. will approach 0.7. As nonathletes are trained, there is more rapid shift to free fatty acid metabolism which is reflected by a lower R.Q. in the early phases of exercise. The serial measurement of R.Q. as an individual steadily exercises below his anaerobic threshold will reflect his ability to utilize lipids as an energy source. The greater the rate of change of R.Q. with time, the greater is his ability to metabolize lipids. Increased utilization of lipids during exercise indicates his augmented capacity to do submaximal long-duration work, therefore, fitness.

Cytochrome c Group↗
PubMedDate not supplied

Urban ectopy in the mountains: carbon monoxide exposure at high altitude.

Environmental exposure to inhaled carbon monoxide (CO) increases coronary artery disease risk. Sudden cardiac death, a frequent manifestation of coronary artery disease, is usually a result of ventricular dysrhythmia. The effect of exposure to CO at sea level (CO/SL) and simulated high (2.1 km) altitudes (CO/HA) on the incidence of cardiac ectopy in subjects with coronary artery disease was investigated. A double-blind crossover study was conducted, with random-order assignment, and each subject served as his own control. Seventeen men with documented coronary artery disease and stable angina pectoris performed cardiopulmonary exercise stress tests after random exposure to either CO or clean air (CA) at sea level (CA/SL) or at a simulated 2.1-km high altitude (CA/HA). The individual CO and HA exposure conditions were each selected to reduce the percentage of oxygen saturation of the subjects' arterial blood by 4%. Subjects' blood carboxyhemoglobin levels were increased from an average of 0.62% after clean-air exposure to 3.91% of saturation after CO exposure. The percentage of oxygen saturation in arterial blood was reduced from a baseline level of 98% to approximately 94% after CO/SL or CA/HA and to approximately 90% after CO/HA. Compared with the CA/SL (i.e., 10 premature ventricular contractions [PVCs]), the average incidence of exercise-induced ventricular ectopy was approximately doubled after all exposures (CO/SL = 18 PVCs, CA/HA = 16 PVCs, and CO/HA = 19 PVCs), and a significant trend (p < .05) of increased ectopy with decreased oxygen saturation in arterial blood was observed. Yet, among subjects who were free from ectopy (n = 11) on CA/SL, only 2 subjects developed ectopy after CO/HA. No episodes of ventricular tachycardia or fibrillation occurred. The findings indicated that exposure to increased levels of hypoxemia, resulting from hypoxic and/or CO exposures, increased the susceptibility to ventricular ectopy during exercise in individuals with stable angina pectoris; however, this risk was nominal for those without ectopy.

Aged↗
PubMedDate not supplied

Urban angina in the mountains: effects of carbon monoxide and mild hypoxemia on subjects with chronic stable angina.

Seventeen men with stable angina pectoris who resided at or near sea level performed cardiopulmonary exercise stress tests after they were exposed to either carbon monoxide (3.9%), carboxyhemoglobin, or clean air. Investigators conducted the tests at sea level, and they simulated 2.1-km altitudes (i.e., reduced arterial oxygen saturation by approximately 4%) in a randomized double-blind experiment in which each subject acted as his or her own control. The duration of symptom-limited exercise, heart rate, indicators of cardiac ischemia and arrhythmia, blood pressure, and respiratory gas exchange were measured. Analyses of variance showed that both independent variables-altitude and carbon monoxide-significantly (p < or = .01) reduced total duration of exercise for the group as a whole (n=17) and reduced the time to onset of angina for a subset of 13 subjects who experienced angina during all four test conditions (p < .05). Time to onset of angina was reduced either after exposure to sea-level carbon monoxide (9%) or to simulated high-altitude clean-air exposures (11%), compared with clean air at sea level. Joint exposure to carbon monoxide at a simulated high altitude reduced the time to onset of angina, relative to clean air, by 18% (p < .05). Other cardiological, hemodynamic, and respiratory physiological parameters were also affected adversely by altitude and carbon monoxide exposures. None of the parameters measured were associated significantly with either altitude or carbon monoxide, indicating that the effects of carbon-monoxide-induced and high-altitude-induced hypoxia were additive. The results of this study suggest that high-altitude conditions exacerbate the effects of carbon monoxide exposures in unacclimatized individuals who have coronary artery disease.

Aged↗
PubMedDate not supplied

Reduction of serum estradiol in postmenopausal women given free access to low-fat high-carbohydrate diet.

The short-term effects of a low-fat (less than 10% of cal) high-fiber (35-45 g.1000 kcal-1.day-1) diet on estradiol levels were studied in 13 postmenopausal women under residential conditions with cafeteria food service. During this diet study (mean +/- SE duration 22 +/- 4.6 days), body weight declined from 84.9 +/- 6.4 to 82.3 +/- 6.0 kg (P less than 0.001). Serum cholesterol and low-density and high-density lipoprotein cholesterol also fell significantly, whereas triglycerides remained constant. Serum estradiol fell from 18.1 +/- 3.6 to 9.4 +/- 2.4 pg/ml (P less than 0.05). This study demonstrates that serum estradiol levels are reduced in normal to over-weight postmenopausal women given free access to a low-fat high-fiber diet. Most of these women were in negative caloric balance during the study, suggesting that short-term changes in caloric balance may affect estrogen synthesis in postmenopausal women prior to a large decrease in fat mass.

Adult↗