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Biomedical subjects

Y A Weiss

Publications and source records attributed to Y A Weiss.

44 records · Page 3Linked to original sources
PubMed1975

Overhydratation and renin in hypertensive patients with terminal renal failure: a hemodynamic study.

Twenty-nine patients with terminal renal failure were treated by periodic hemodialysis for 2 to 18 months. Serial determinations of blood pressure, blood volume, cardiac output, exchangeable sodium and plasma renin activity were performed. Bilateral nephrectomy was performed in 17 patients and followed by a fall in blood pressure. Cardiac index was elevated in all patients but the blood pressure changes were mainly related to resistance changes. In non-nephrectomized patients, mean arterial pressure was directly correlated to plasma volume (P less than 0.0001), exchangeable sodium (P less than 0.01) and plasma renin activity (P less than 0.001). In anephric patients, mean arterial pressure was only directly correlated to plasma volume (P less than o.005). The slope of the curve relating arterial pressure to plasma volume was significantly shallower in nephrectomized than in non-nephrectomized patients, indicating a lower sensitivity of pressure to volume changes. The study provides evidence that, in hypertensive patients with chronic renal failure, the positive pressure-volume relationship is the fundamental cause of the high blood pressure and that the renin-angiotensin system acts mainly by changing the sensitivity of this mechanism.

Adolescent↗
PubMedDate not supplied

Pharmacokinetics and hepatic extraction ratio of pindolol in hypertensive patients with normal and impaired renal function.

The intravenous and oral pharmacokinetics and the hepatic extraction ratio of pindolol were determined in 24 hypertensive patients with normal or impaired renal function. In patients with normal renal function, the total clearance was the sum of equal parts of the renal and nonrenal clearances. The nonrenal clearance was found to be equal to the hepatic clearance directly measured from the hepatic extraction ratio. Compared to patients with normal renal function, patients with chronic renal failure exhibited (i) unchanged K12 and K21 and nonrenal clearances, and (ii) significantly decreased values in half-life of the beta phase, Kel, and total renal clearance. The renal clearance was positively correlated (P less than 0.01) to the creatinine clearance. Bioavailability was significantly reduced (P less than 0.01) in the patients with renal failure. Assuming that the nonrenal clearance was equal to the hepatic clearance, the study provides evidence that, in patients with renal insufficiency, (i) no increased metabolism accompanies the decrease in renal function, and (ii) decreased availability is due to reduced absorption.

Administration, Oral↗
PubMedDate not supplied

Antihypertensive effects and plasma levels of guanfacine in man.

The antihypertensive effect and the plasma levels of guanfacine were studied for two months in 25 patients with sustained essential hypertension. In three patients, blood pressure was unchanged. In ten patients, blood pressure returned to the normal range within 15 days, at a daily dose of 2 mg. In 12 patients, increasing doses were necessary to normalize the blood pressure within two months. In these cases, the decrease in systolic pressure was negatively correlated with the daily dose of guanfacine (r = -0.40) and the steady-state plasma level (r = -0.62; P less than 0.01); analysis of the curves showed that the normalization of blood pressure coincided with a plasma drug level of 8 ng/ml, i.e., a 4-mg daily dose. This study demonstrated the efficacy of guanfacine monotherapy in hypertension and suggests that the normalization rate of blood pressure levels does not further increase with daily doses higher than 4 mg.

Adult↗
PubMedDate not supplied

Essential hypertension: an approach to clinical data by the use of models.

A new approach, based on animal circulatory models, was proposed for the study of clinical data in hypertension. Clinical data were identified with steady states in models. From the study of models, possible impairments, susceptible to account for the observed derivations of steady states in men, were analyzed. To be specific, the 1967-Guyton-Coleman model was confronted with a set of data on essential hypertension. The approach afforded a physiological interpretation for statistical results performed on clinical data.

Animals↗