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Biomedical subjects

T Bledsoe

Publications and source records attributed to T Bledsoe.

At least 19 recordsLinked to original sources
PubMed1990

The Rand Health Insurance Experiment and HMOs.

The Rand Health Insurance Experiment (HIE) provides the most persuasive evidence to date on the relative effects of health maintenance organization (HMO) and fee-for-service care on utilization, costs, client satisfaction, and health care outcomes. Publications from the HIE have suggested that HMO care was associated with lower costs because of reduced hospitalizations, lower client satisfaction, and poorer health status among the subgroup with limited incomes and initial health status. In our view, the evidence justifies the conclusions related to utilization, costs, and satisfaction, but not the suggestion that HMO care had adverse health effects on low-income, sick individuals.

Adult↗
PubMed1983

Hormonal responses to acute volume changes in anephric subjects.

The response of plasma aldosterone and cortisol concentrations to acute volume depletion was studied in 18 chronically anephric subjects and four recently nephrectomized subjects. Volume-depleting hemodialysis and hemodialysis without volume depletion produced insignificant changes in plasma aldosterone concentrations in chronically anephric subjects. Failure of volume depletion to increase plasma aldosterone concentrations in these subjects could not be attributed to reductions in plasma potassium concentrations and was in marked contrast to the effect on plasma cortisol concentrations, which increased significantly during volume depletion. Changes in plasma cortisol concentrations exhibited a negative correlation with changes in diastolic blood pressure (r = -0.712, P less than 0.001) and were shown to correspond to similar changes in plasma ACTH concentrations. Comparable increases in plasma cortisol and ACTH concentrations were also demonstrated in the studies on recently nephrectomized subjects, who, in contrast to chronically anephric subjects, exhibited increases in plasma aldosterone concentrations which were concordant with the changes in plasma cortisol and ACTH concentrations. These findings suggest that plasma aldosterone concentrations are regulated by a volume-sensitive mechanism in recently nephrectomized subjects but not in chronically anephric subjects. We interpret these data as evidence of aldosterone responsiveness to ACTH that persists for a limited time only after removal of the stimulus provided by the renin-angiotensin system. Volume-related changes in plasma cortisol and ACTH concentrations occur in the absence of stimulation by a functioning renin-angiotensin system.

Adolescent↗
PubMed1979

Dissociation of the diurnal variation of aldosterone and cortisol in anephric subjects.

Diurnal variation of plasma aldosterone and cortisol concentration in man was studied in 13 anephric subjects and 7 normal subjects. All subjects were ambulatory and active throughout the study except during an 8-hour sleep period. Six anephric subjects received Kayexalate (sodium polystyrene sulfonate) during the studies to prevent potassium accumulation and increase in plasma potassium concentration. Diurnal variation of plasma aldosterone concentration with peak and nadir concentrations at 12:00 noon and 12:00 midnight respectively was demonstrated in the studies on normal subjects. Changes in plasma aldosterone concentration were not significantly correlated with changes in plasma concentration but were highly correlated with changes in PRA (P less than 0.001). There was a highly significant correlation between plasma aldosterone and potassium concentration in the anephric subjects studied without Kayexalate administration (P less than 0.001). In the anephric subjects who received Kayexalate, plasma aldosterone and potassium concentration remained stable, and no correlation could be demonstrated. No diurnal variation of plasma aldosterone concentration could be demonstrated in either group of anephric subjects, whereas plasma cortisol concentration varied as in the studies on normal subjects. Conclusion. Diurnal variation of plasma aldosterone concentration is dependent on continued stimulation by the renin-angiotensin system. Loss of this stimulation has no demonstrable effect on the diurnal variation of plasma cortisol concentration.

Adult↗
PubMed1979

Studies comparing the metabolic clearance rate of 11 beta,17,21-trihydroxypregn-1,4-diene-3,20-dione (prednisolone) after oral 17,21-dihydroxypregn-1,4-diene-3,11,20-trione and intravenous prednisolone.

The MCR of prednisolone (11 beta,17,21-trihydroxypregn-1,4-diene-3,20-dione) and the absorption of prednisone (17,21-dihydroxypregn 1,4-diene-3,11,20-trione) were studied in five normal subjects and four patients. Plasma and urinary prednisolone were measured by a competitive radioassay. The MCR was determined after iv administration of 30 mg nonisotopic prednisolone using one-compartment (MCR1) and two-compartment (MCR2) analyses. These values were compared with the MCR determined after oral administration of nonisotopic prednisone (MCR0). MCR1 and MCR2 were closely correlated, indicating the applicability of first order kinetics to the study of prednisolone metabolism. In subjects with normal gastrointestinal function, MCR0 was consistently lower than MCR2 (mean MCR2 = 0.175 liters/h.kg; MCR0 = 0.145 liters/h.kg). In two patients with steroid malabsorption, the MCR0 was significantly greater than MCR2. Knowledge of the expected relationship between MCR0 and MCR2 allowed quantitation of the degree of malabsorption. With or without impaired absorption, the absorptive process was essentially complete by the time of the peak plasma concentration. Estrogen therapy lowered the MCR0, and high prednisone dose increased the MCR0. Those effects and the effects of iv prednisolone administration on the MCR are explained by the effects of plasma protein binding of prednisolone. These studies demonstrate the usefulness of the oral MCR determination in the evaluation of steroid absorption and metabolism.

Administration, Oral↗
PubMed1977

A comparison of primary care educational experiences in two urban pediatric settings.

The purpose of this study was to initiate the evaluation of the ambulatory care training programs of the Johns Hopkins Medical Institutions and affiliated programs as resources for primary care education, and to provide input into the development of a primary care educational curriculum. It was determined that these settings fell short of fulfilling an a priori set of educational objectives designed to emphasize primary as opposed to secondary care. Foresight must be exercised in the selection of sites and the design of the clinical practice of an acceptable training program in primary care is desired.

Ambulatory Care↗
PubMed1973

Modulation of plasma aldosterone concentration by plasma potassium in anephric man in the absence of a change in potassium balance.

In studies on seven anephric patients, glucose and insulin administration before hemodialysis produced a significant reduction in plasma potassium concentration (mean reduction = 1.3, 1.7, and 1.4 meq/liter at 60, 120, and 180 min, respectively) which was accompanied by a significant and sustained reduction in plasma aldosterone concentration. There was a significant correlation between plasma aldosterone and plasma potassium concentration (r = +0.74, P < 0.001) and between changes in the concentration of plasma aldosterone occurring in individual patients and the corresponding changes in plasma potassium concentration (r = +0.52, P < 0.01). There was no significant change in plasma sodium concentration, and plasma corticoid concentration, which was monitored as an index of ACTH elaboration, was reduced at 60 min but increased subsequently as symptoms attributable to hypoglycemia were observed. These studies demonstrate that plasma aldosterone concentration can be modulated acutely by transitory changes in plasma potassium concentration without a change in potassium balance. The effect of glucose and insulin administration on intracellular potassium in the adrenal cortex is uncertain, and although increased net movement of potassium into cells is the presumptive mechanism of the reduction in plasma potassium concentration, whether the potassium content of the adrenal cortex may have increased or decreased or remained essentially unchanged, cannot be inferred from our data.

Aldosterone↗