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Biomedical subjects

J L Probstfield

Publications and source records attributed to J L Probstfield.

54 records · Page 3Linked to original sources
PubMed1985

Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil.

This study's purpose was to evaluate the fasting human plasma lipid and lipoprotein responses to dietary beef fat (BF) by comparison with coconut oil (CO) and safflower oil (SO), fats customarily classified as saturated and polyunsaturated. Nineteen free-living normolipidemic men aged 25.6 +/- 3.5 yr consumed centrally-prepared lunches and dinners of common foods having 35% fat calories, 60% of which was the test fat. The test fats were isocalorically substituted, and each fed for five weeks in random sequences with intervening five weeks of habitual diets. Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations among individuals follows the same relative rank regardless of diet. Triglycerides (TG) concentrations among individuals also maintain their relative rank regardless of diet but in a different order from that of the cholesterols. Plasma TC, HDL-C, and LDL-C responses to BF were significantly lower and TG higher than to CO. As compared to SO, BF produced equivalent levels of TG, HDL-C, and LDL-C and marginally higher TC. Thus, the customary consideration of BF as "saturated" and grouping it with CO appears unwarranted.

Adult↗
PubMed1984

Clinical trials methods and the practice of medicine.

An important potential byproduct from clinical trials is validated clinical methods applicable to clinical practice. The potential for improved patient care is separate from the scientific and intellectual answers gained in such trials. The current mechanisms for the transfer of methodological information from clinical trials are inefficient and have identifiable barriers. Methods validated in clinical trials must be recognized and accentuated as a valuable resource. A central repository of clinical trials' methods and a retrieval system dedicated to this unique body of scientific literature is warranted. Reports of methodological advances from clinical trials should be published in the literature read by clinical practitioners. The effective transfer of methods information from clinical trials to the office of the clinical practitioner is possible but requires increased efforts on the part of clinical trials scientists.

Clinical Trials as Topic↗
PubMed1984

Coronary risk factors and exercise test performance in asymptomatic hypercholesterolemic men: application of proportional hazards analysis.

The association of established coronary risk factors with submaximal graded treadmill exercise test performance was examined in 6,850 asymptomatic, white 34--59-year-old hypercholesterolemic men screened between 1973 and 1976 at 12 North American Lipid Research Clinics for participation in their Coronary Primary Prevention Trial. The prevalence of ischemic electrocardiographic responses (greater than or equal to 1 mm S-T segment depression) was 8.6%. The Cox proportional hazards method was adapted so as to take into account the level of exercise at which ischemic responses occurred and to which subjects without ischemic responses were exposed. The results were compared with those obtained by standard logistic regression. In both models, age, blood pressure, plasma cholesterol, and (inversely) plasma high-density lipoprotein cholesterol and alcohol consumption were significant independent predictors of an ischemic response to exercise. Surprisingly, ischemic responses were less frequent in smokers than in nonsmokers. However, when the proportional hazards method was used, cigarette smoking was weakly but significantly (p less than 0.01) predictive of an ischemic response on the treadmill. Results from this model differed from those of the logistic model because the former takes into account the reduced exercise capacity of smokers, which renders them less likely to reach workloads sufficient to induce myocardial ischemia. The proportional hazards model similarly demonstrated a possible beneficial effect of habitual physical activity which was not apparent in the logistic model. Quetelet index and plasma triglyceride were only weakly associated with the probability of an ischemic response, and did not contribute significantly to either model.

Adult↗
PubMed1984

Intervention specialist: new role for dietitians' counseling skills.

Dietitians who want to expand their clinical responsibilities beyond dietary counseling should consider the role of the intervention specialist. The role is a logical expansion of the duties of the dietitian who is already serving as a health behavior counselor. The concept of dietitians' functioning as intervention specialists originated in clinical trials, when they served as adherence counselors. The intervention specialists in the clinical trials used the health behavior counseling process to help research participants adhere to the trials' protocols. This counseling process uses a systematic, problem-solving approach to assess, diagnose, intervene, and follow up on a targeted behavioral problem. Dietitians can prepare for the expanded counseling role of intervention specialist through interviewing and counseling skill assessment and further training. They must take an active role in defining how the services of an intervention specialist can be beneficial to physicians as well as to their patients. They should address the cost-effectiveness of behavior counseling in order to justify the increased initial costs. Dietitians will need to actively promote the role of intervention specialist in the medical community if they want this opportunity for increased professional responsibility.

Behavior Therapy↗
PubMed1983

Alterations in human serum alkaline phosphatase and its isoenzymes by hypolipidemic agents: colestipol and clofibrate.

Total serum alkaline phosphatase (TSAP) determinations were done as part of the biochemical screening in comparative studies of lipid lowering agents in type lla hyperlipoproteinemic patients. TSAP determinations were made by using a modification of the Bessey-Lowry method and the Statland method. Increases in TSAP following colestipol treatment of 20% (P less than 0.05) and 32% (P less than 0.005) were seen by using the respective methods. Isoenzymatic determinations were done by employing the Statland method and all fractions were increased from baseline levels during colestipol therapy. Clofibrate was associated with 34% (P less than 0.005) and 28% (P less than 0.005) reductions in TSAP activity by using the respective methods; significant reductions in both "bone" and "other" isoenzymatic components occurred. Gamma-glutamyltransferase (gamma GT) results did not consistently reflect TSAP or "liver" isoenzyme results.

Adult↗
PubMed1983

Development of standardized simulated patients for quality control of the clinical interview.

The evaluation and training of clinical trial staff who counsel patients in lifestyle changes for disease prevention is aided by a review of videorecorded interviews conducted with a simulated patient. This report describes the Inventory of Simulated Patient Characteristics, a listing of 34 generic parameters for developing a simulated patient for use in staff training and evaluation in counseling. The Inventory creates a complete person in all critical aspects of counseling for lifestyle change (e.g., daily routines, family, job). The Inventory was used in the Lipid Research Clinics' Coronary Primary Prevention Trial (CPPT) to examine the trial staff's skills in counseling for regimen adherence. In 1979 and 1980, 85 and 52 clinic staff, respectively, conducted a total of 548 interviews with four different simulated patients developed using the Inventory, and rated the portrayals as highly realistic. The Inventory also was used to verify that the simulated patient portrayals were greater than 90% faithful to their characterizations. While simulated patients limited to specific clinical syndromes have been used widely in medical education, no guidelines exist for their use in training trial staff in regimen counseling. The Inventory provides a simple template for creating simulated patients with broad characterizations that closely mimic actual trial participants.

Clinical Trials as Topic↗
PubMed1982

Occupational screenings: recruitment from private industry.

Occupational screening involving private sector employees represents a source with relatively high volumes of initial contacts and entries, a low ratio of entries to initial contacts, and a relatively high effort level requirement for the recruitment team. In the CPPT, all centers used this strategy, to provide, overall, 26% of initial contacts, 20% of first protocol visits and 17% of entries. Occupational screening is costly and involves careful planning and implementation of complex arrangements. Procedures for contacting industries and conducting screenings are described. Screening yield was inversely related to company size.

Adult↗
PubMed1981

Effect of colestipol and clofibrate on plasma lipid and lipoproteins in type IIa hyperlipoproteinemia.

The effects of 2.0 g of clofibrate and 15, 20 and 30 g of colestipol on plasma lipid and lipoprotein levels were evaluated in adult patients with Type IIa hyperlipoproteinemia. Clofibrate treatment was associated with decreases in 11.0% in plasma cholesterol. 15.2% in LDL cholesterol, 26.1% in triglycerides, and an 11.3% increase in HDL cholesterol. The reductions in total cholesterol with the various doses of colestipol ranged from 11.9 to 17.8% and reductions in LDL cholesterol ranged from 16.1 to 27.3%. Colestipol treatment was not associated with any significant change in HDL cholesterol levels and minor increases in triglycerides. The addition of clofibrate to patients receiving colestipol resulted in a significant increase in HDL cholesterol and a decrease in triglycerides, but no additional reduction in total or LDL cholesterol.

Adult↗
PubMed1981

TSH response to TRH in euthyroid, hypercholesterolemic patients treated with graded doses of dextrothyroxine.

In an attempt to determine the minimum dose of D-Thyroxine (D-T4) which will suppress pituitary TSH response to TRH, we have treated 6 euthyroid, hypercholesterolemic patients with graded doses of D-T4. TSH response was suppressed in 3 patients with 3 mg and in the remaining 3 patients with 4 mg D-T4 administered once daily. The mean TSH suppressive dose of 3.5 mg, as determined in this study, is considerably less than the 6 mg daily dose given to patients treated with D-T4 in the Coronary Drug Project. This suggests that the adverse effects observed with D-T4 treatment in the Coronary Drug Project may have been due to mild, undetected hyperthryroidism. D-T4 treatment in our patients was not associated with an increase in heart rate or ventricular ectopic beats as determined by Holter monitoring. However, bile samples obtained at the time of TSH suppression showed a significant increase in lithogenic index. In four patients, TSH suppressive doses of D-T4 were associated with a 12% decrease in mean cholesterol and a 17% decrease in mean LDL cholesterol concentrations.

Adult↗
PubMed1975

Ethacrynic acid induced inotropism.

Ethacrynic acid (ECA), a sulfhydryl group inhibiting diuretic was examined for positive inotropic effects. These were found to be present in isolated guinea pig left atria studied in 0.9 and 1.8 mM Ca bathing solutions and were partially dependent upon adrenergic mechanisms (presumably secondary to norepinephrine release from sympathetic nerve endings) and partly independent of such mechanisms as demonstrated by propranolol induced beta-blockade and reserpine-induced catecholamine depletion. The mechanism of the non-beta adrenergic inotropism is unclear but may relate to the ability of ECA to inhibit the sarcolemmal Na-K-Mg-dependent ATPase. ECA-induced premature contractile failure occurred in all atria as well as a late increase in diastolic tension, the latter being comparable to that described for toxic doses of cardiac glycosides in similar preparations.

Animals↗
PubMedDate not supplied

The systolic hypertension in the elderly program. Implications for nursing practice and research.

The Systolic Hypertension in the Elderly Program (SHEP) encompasses two clinical trials--a pilot study and a full-scale trial--investigating the safety and efficacy of antihypertensive therapy for patients aged 60 years and over with isolated systolic hypertension (ISH), that is, systolic blood pressure (SBP) greater than or equal to 160 mmHg and diastolic blood pressure (DBP) less than 90 mmHg. An optimal result of the full-scale trial should lead to recommendations for prescription of effective therapy that preserves the quality of life while reducing the long-term risks of stroke, other cardiovascular disease, and death. This article briefly describes the design, protocol, and organization for the pilot and fullscale SHEP studies. In these trials the nurses help plan study protocol, coordinate patient recruitment, provide patient care, and maintain protocol compliance. In order to accomplish their role in data collection and reporting, they undergo comprehensive training and certification. Nurses utilize the multicenter clinical trial as an opportunity to participate in research, both independently and collaboratively. The specific roles of nurses within these trials, as well as features of these trials that relate to nursing practice and research, are discussed.

Aged↗
PubMedDate not supplied

Decrease in plasma high-density lipoprotein cholesterol levels at puberty in boys with delayed adolescence. Correlation with plasma testosterone levels.

A three-phase study tested the hypothesis that the decrease in the high-density lipoprotein cholesterol (HDL-C) level observed in boys at puberty is related to an increase in the plasma testosterone concentration. In phase I, 57 boys aged 10 to 17 years were categorized into four pubertal stages based on clinical parameters and plasma testosterone levels. These four groups showed increasing plasma testosterone values and decreasing HDL-C levels. In phase II, 14 boys with delayed adolescence were treated with testosterone enanthate (100, 200, and 200 mg/mo, respectively, for three months). Plasma testosterone levels during therapy were in the adult male range. Levels of HDL-C decreased by a mean of 7.4 mg/dL (0.20 mmol/L) and 13.7 mg/dL (0.35 mmol/L), respectively, after the first two doses. In phase III, 13 boys with delayed adolescence demonstrated increasing plasma testosterone levels and decreasing HDL-C levels (-12.0 mg/dL [-0.30 mmol/L]) during spontaneous puberty. Levels of HDL-C and apolipoprotein A-1 were correlated during induced and spontaneous puberty. Testosterone should be considered a significant determinant (not necessarily directly causal) of plasma HDL-C levels during pubertal development.

Adolescent↗