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Biomedical subjects

Raymond R Townsend

Publications and source records attributed to Raymond R Townsend.

53 records · Page 3Linked to original sources
PubMed2003

The Chronic Renal Insufficiency Cohort (CRIC) Study: Design and Methods.

Insights into end-stage renal disease have emerged from many investigations but less is known about the epidemiology of chronic renal insufficiency (CRI) and its relationship to cardiovascular disease (CVD). The Chronic Renal Insufficiency Cohort (CRIC) Study was established to examine risk factors for progression of CRI and CVD among CRI patients and develop models to identify high-risk subgroups, informing future treatment trials, and increasing application of preventive therapies. CRIC will enroll approximately 3000 individuals at seven sites and follow participants for up to 5 yr. CRIC will include a racially and ethnically diverse group of adults aged 21 to 74 yr with a broad spectrum of renal disease severity, half of whom have diagnosed diabetes mellitus. CRIC will exclude subjects with polycystic kidney disease and those on active immunosuppression for glomerulonephritis. Subjects will undergo extensive clinical evaluation at baseline and at annual clinic visits and via telephone at 6 mo intervals. Data on quality of life, dietary assessment, physical activity, health behaviors, depression, cognitive function, health care resource utilization, as well as blood and urine specimens will be collected annually. (125)I-iothalamate clearances and CVD evaluations including a 12-lead surface electrocardiogram, an echocardiogram, and coronary electron beam or spiral CT will be performed serially. Analyses planned in CRIC will provide important information on potential risk factors for progressive CRI and CVD. Insights from CRIC should lead to the formulation of hypotheses regarding therapy that will serve as the basis for targeted interventional trials focused on reducing the burden of CRI and CVD.

Adult↗
PubMed2002

Large and small artery compliance changes during hemodialysis.

BACKGROUND: Cardiovascular disease is the major cause of mortality and morbidity in patients undergoing hemodialysis. Reduced arterial compliance is an independent predictor of cardiovascular mortality in end stage renal disease and can be measured noninvasively using pulse wave analysis technology. METHODS: Ten chronic hemodialysis patients were evaluated using pulse wave analysis to determine large and small vessel compliance before hemodialysis, midway through the treatment, and at the end of the treatment. Serum calcium was measured before and after hemodialysis. RESULTS: No significant changes in systolic blood pressure (BP), diastolic BP, pulse pressure, or heart rate occurred during hemodialysis. A significant decrease in small vessel compliance (C2) occurred during the treatment, with the mean C2 decreasing from 5.6 +/- 2.7 mL/mm Hg x 10 predialysis to 3.3 +/- 1.5 mL/mm Hg x 10 midway through the treatment (P = .04) and to 3.9 +/- 4.3 mL/mm Hg x 10 at the end of the dialysis treatment. There was no significant change in large vessel compliance (C1). Serum calcium increased significantly during the dialysis treatment from 8.0 +/- 1.2 mg/dL to 9.8 +/- 0.9 mg/dL (P = .003). CONCLUSIONS: Significant decreases in small artery compliance occur without systolic or diastolic BP changes during routine hemodialysis. A significant increase in serum calcium also occurred during hemodialysis. Measurements of arterial compliance during hemodialysis may be an important tool to identify patients with vascular responses, which may place them at greater risk for cardiovascular disease.

Adult↗
PubMed2002

Physicians' preferences for active-controlled versus placebo-controlled trials of new antihypertensive drugs.

OBJECTIVE: To evaluate physicians' preferences for referring patients to, and using information from, active-controlled trials (ACTs) versus placebo-controlled trials (PCTs) of new antihypertensive drugs. DESIGN AND SETTING: Nationwide mailed survey, with telephone contact of nonresponders to assess nonresponse bias. PARTICIPANTS: One thousand two hundred primary care physicians randomly selected from the American Medical Association's Master File. Of 1,154 physicians eligible to respond, 651 (56.4%) returned completed questionnaires. MEASUREMENTS AND MAIN RESULTS: We measured physicians' stated willingness to encourage hypertensive patients to enroll in ACTs and PCTs of new antihypertensive drugs, their views of the relative merits of ACTs versus PCTs, their stated willingness to prescribe new drugs tested in ACTs or PCTs, and their views regarding the overall justifiability of the 2 designs. Physicians were significantly more likely to indicate they would encourage their patients to enroll in ACTs than in PCTs (P <.0001). Physicians thought ACTs provided more valuable information for their practices, were more likely to lead to a public health benefit, offered enrolled patients greater opportunity for personal benefit, and were less likely to expose enrolled patients to unnecessary risks (all P <.0001). Physicians were more likely to prescribe new drugs that had been compared in ACTs (P <.0001), and viewed ACTs as a more justifiable method for testing new antihypertensive drugs (P <.0001). There was no evidence of nonresponse bias for these main results. CONCLUSIONS: Although PCTs remain the standard method for testing new antihypertensive drugs, physicians strongly prefer ACTs. Using ACTs to test new antihypertensive drugs may enhance the efficiency of patient recruitment and more strongly influence physicians' prescribing practices.

Antihypertensive Agents↗
PubMed2002

Differential effect of insulin on saturated and unsaturated fatty acids.

Fatty acids fulfill important roles in physiology. The plasma concentrations of fatty acids are principally regulated by insulin, which suppresses the release of fatty acids from lipid stores, and catecholamines, which increase their release from lipid stores. Although insulin regulates the concentration of plasma free fatty acids (FFAs), little is known about the relative effects of insulin on the saturated compared with the unsaturated plasma fatty acids. In the current study, we specifically measured the plasma concentration of 3 saturated and 4 unsaturated fatty acids along with an estimate of lipolytic activity using a stable isotope of glycerol during a 3-hour, 1-step, euglycemic clamp study in humans. The data showed the expected decline in plasma fatty acids from 0.26 +/- 0.02 to 0.06 +/- 0.01 micromol/mL. Saturated fatty acids were reduced from 0.12 +/- 0.01 to 0.05 +/- 0.005 micromol/mL and unsaturated fatty acids were reduced from 0.11 +/- 0.01 to 0.01 +/- 0.001 micromol/mL after 3 hours of insulin infusion. At baseline, the ratio of saturated to unsaturated fatty acid was 55:45, which increased to 82:18 by the end of study. The changes in fatty acids were evident within 1 hour. Whole body lipolytic rates were measured with deuterated glycerol and decreased from 1.48 +/- 0.56 micromol x kg(-1) x min(-1) to 0.75 +/- 0.34 micromol x kg(-1) x min(-1). Baseline postabsorptive plasma fatty acid concentrations were significantly correlated to insulin sensitivity (M value) as measured during the euglycemic clamp. There were no significant differences between the more insulin-sensitive subjects when compared with the more insulin-resistant subjects with respect to the relative decreases in saturated and unsaturated fatty acids during insulin infusion. These data demonstrate a sustained differential effect of insulin on the plasma fatty acid profile.

Adolescent↗
PubMedDate not supplied

Blood pressure changes in the leg on standing.

Normotensive and hypertensive patients develop peripheral arterial disease. The authors hypothesized that significant changes in lower extremity blood pressures occur upon standing, which could play a role in the pathogenesis of peripheral arterial disease. Forty-one subjects had blood pressure measurements performed in the arm and ankle in the supine and standing positions. The data show a marked increase in leg blood pressure on assuming the standing position, with mean increases of 65 mm Hg in systolic and 62 mm Hg in diastolic blood pressure in the lower extremities, compared with the arm on standing. In addition, the changes in diastolic pressure in the leg on standing were significantly correlated to height (r=0.47; p<0.002). These data reveal a previously unappreciated aspect of blood pressure, namely a large increase in lower extremity blood pressure values on standing, which may predispose to peripheral arterial disease.

Adult↗
PubMedDate not supplied

Aldersterone redux.

Explore the source record for details and available documents.

Aldosterone↗