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Biomedical subjects

J W Hollifield

Publications and source records attributed to J W Hollifield.

At least 19 recordsLinked to original sources
PubMed1991

The effects of benazepril, a new angiotensin-converting enzyme inhibitor, in mild to moderate essential hypertension: a multicenter study.

Benazepril hydrochloride is a new angiotensin-converting enzyme inhibitor. In a multicenter study, 206 patients with mild to moderate hypertension were randomized to receive benazepril at a dose of 2, 5, 10, or 20 mg, hydrochlorothiazide, 25 mg, or placebo once daily for 4 weeks. The 20 mg dosage of benazepril lowered blood pressure to a degree equal to that of 25 mg hydrochlorothiazide: -12.2/7.7 mm Hg and -13.4/-7.5 mm Hg, respectively. Hydrochlorothiazide proved to be more effective in black subjects. At lower dosage levels of benazepril (2, 5, and 10 mg), blood pressure reduction was not significantly different from that with placebo. In those patients who failed to achieve goal diastolic blood pressure of less than 90 mm Hg with monotherapy after 4 weeks, the addition of open-label hydrochlorothiazide (25 mg/day) to benazepril, hydrochlorothiazide, or placebo produced a substantial additional decrease in blood pressure over a 2-week period. No definite adverse effects on hematologic measurements, serum biochemistry test results, or urinalyses were noted. Subjective adverse experiences were common in all groups but except in three or possibly four instances were not considered causally related to the study drug.

Adult↗
PubMed1989

Thiazide treatment of systemic hypertension: effects on serum magnesium and ventricular ectopic activity.

Clinical and investigational evidence has proved an association between thiazide-induced electrolyte imbalances and ventricular arrhythmias. It is hypothesized that this increases the potential for sudden unexplained death. Elderly hypertensive patients are at particular risk because of their tendency to have significantly depressed serum magnesium levels, which decrease even further when treated with thiazide diuretics. Potassium supplementation does not effectively restore electrolyte balance unless accompanied by magnesium. Therefore, concomitant administration of potassium and magnesium supplementation appears to be an approach to reducing the risk of arrhythmias and death in thiazide-treated hypertensive patients.

Aged↗
PubMed1989

Electrolyte disarray and cardiovascular disease.

Thiazide diuretics have frequently been recommended as initial therapy in patients with mild to moderate hypertension. However, their undesirable metabolic consequences have been suspected of contributing to increases in cardiovascular morbidity and mortality. Even at low doses, there is a definite decrease in both potassium and magnesium levels. The degree of decrease in potassium and magnesium levels has been shown to be directly related to the hydrochlorothiazide dosage. Many investigators have now reported an increase in ventricular ectopy associated with diuretic-induced hypokalemia. Whereas there is no single study that conclusively proves that thiazide therapy results in malignant arrhythmias and an increased risk of sudden death, the circumstantial evidence is strong. Although sodium restriction is critical to potassium restoration, it rarely works alone. Potassium chloride supplementation can be effective in restoring potassium but not magnesium. Potassium-sparing diuretic combinations can both prevent and treat hypokalemia and hypomagnesemia, possibly reducing the risk of potentially lethal arrhythmias and sudden death.

Arrhythmias, Cardiac↗
PubMed1987

Magnesium depletion, diuretics, and arrhythmias.

Increasing information on the potentially serious risks of potassium and magnesium depletion associated with diuretic therapy demands a clinical focus on understanding the factors involved and on methods for preventing these electrolyte deficiencies. Data suggest that serum potassium and magnesium levels may be normal in the presence of tissue depletion, but decreases in serum levels are almost always associated with tissue and whole-body depletion of these electrolytes in patients in whom such depletion cannot be risked. Ventricular ectopy has also been associated with depletion of potassium and magnesium, which may explain the increased risk of sudden unexpected death in hypertensive patients. Any clinician who treats hypertension or congestive heart failure must consider whether to replete potassium and magnesium in patients already receiving diuretic therapy, or, better still, consider how to prevent depletion of these electrolytes in patients in whom such depletion cannot be risked. If prevention is selected, the clinician must then evaluate the data on available diuretic combinations for efficacy in electrolyte conservation, bioavailability, and dosage convenience. The combination of triamterene and hydrochlorothiazide (Maxzide, 75 mg triamterene/50 mg hydrochlorothiazide) has demonstrated electrolyte conservation, with bioavailability and dosage convenience.

Arrhythmias, Cardiac↗
PubMed1979

Prognostic factors in adrenal cortical tumors. A mathematical analysis of clinical and morphologic data.

Forty-one patients with adrenal cortical tumors were evaluated retrospectively for the presence of histologic and non-histologic features associated with malignant behavior. The patients who survived operation were followed at least five years. The association of these features with subsequent metastasis was examined by both parametric and nonparametric statistical methods. Twelve criteria were statistically significant in predicting subsequent metastasis. The most significant of these were: clinical evidence of weight loss, broad fibrous bands traversing the tumor, a diffuse growth pattern, vascular invasion, tumor cell necrosis, and tumor mass. The tendency toward metastasis for each tumor was expressed in indices that correlated well with diagnoses made by conventional histologic means, but were more accurate in predicting subsequent clinical behavior than nonquantitative methods of evaluation.

Adolescent↗
PubMed1979

Reduction of plasma renin activity by inhibition of the fatty acid cyclooxygenase in human subjects: independence of sodium retention.

We carried out the present studies to determine whether the suppression of plasma renin activity (PRA) that follows inhibition of prostaglandin (PG) synthesis can be dissociated from the sodium-retaining effects of these drugs. In an initial investigation we studied the effect of indomethacin on PRA in normal subjects in balance on a 10 mM Na+ diet to prevent Na+ retention. Under these experimental conditions indomethacin did not lower PRA even though the fatty acid cyclooxygenase was inhibited, as indicated by a greater than 70% reduction in the major urinary metabolite of prostaglandin E (PGE-M). Sodium depletion leads to enhanced sympathetic activity. We therefore studied the effect of indomethacin on a group of subjects in 10 mM Na+ balance in whom the effect of increased beta-sympathetic activity was blocked by the administration of propranolol. In this group, indomethacin caused 65% suppression of PGE-M and had no effect on Na+ balance, but reversibly reduced PRA in the supine and upright positions by 84% and 70%, respectively. In normal subjects in 10 mM Na+ balance, the isoproterenol-induced increase in PRA also was unaffected by indomethacin. These data establish that inhibition of the cyclooxygenase can result in a reduction of PRA that is independent of changes in Na+ balance or beta-sympathetic tone.

Adult↗
PubMed1979

Primary aldosteronism: diagnosis, localization, and treatment.

New diagnostic techniques have enhanced the detection of primary aldosteronism. However, the response of blood pressure after operation in unilateral and bilateral adrenal disease is different. We have compared four localizing techniques--adrenal venography, adrenal isotopic scanning, a modified adrenal venous sampling for steroid measurements, and the anomalous postural decrease in plasma aldosterone concentration--in 51 patients with primary aldosteronism, all of whom had undergone operative confirmation. Adrenalectomy resulted in normal blood pressure in 59%, improvement in 25%, and no change in 16%. Correct localization of the lesion was obtained in 47% by the adrenal isotopic scan, in 66% by adrenal venography, and in 91% by the modified adrenal venous hormone technique despite four false-positives. Of the 26 patients with an anomalous postural decrease in plasma aldosterone, 88% had a unilateral lesion.

Adenoma↗
PubMed1979

Revascularization of the poorly functioning kidney.

The effect of renal vascularization on renal function in kidneys with poor preoperative excretory function is summarized in this report. Twenty-five patients with kidneys having preoperative creatinine clearance of less than 30 ml/min, as determined during split renal function studies (SRFS), which were revascularized for treatment of secondary renovascular hypertension and then were reevaluated by repeat SRFS form the basis of this report. There were 13 male and 12 female patients. The type of renal artery lesion was atherosclerotic in 21 patients and fibromuscular dysplastic in four patients. Eight individuals had total renal artery occlusion. Significant contralateral renal artery disease was present in 15 patients (60%). Preoperative creatinine clearances in the affected kidneys ranged from 0.27 ml/min (mean, 16 +/- 9 ml/min). after operation, creatinine clearances ranged from 0 to 72 ml/min (mean, 32 +/- 16 ml/mn). Fifteen of the 16 kidneys with preoperative creatinine clearances less than 20 ml/min had improvement in renal function following revascularization (P less than 0.01). Improvement (60%) or cure (36%) in hypertension followed revascularization in 24 of the 25 patients. The most dependable predictor of successful management of both hypertension and retrieval of renal function in these patients was the arteriographic demonstration of a patent distal vessel without evidence of severe intrarenal stenoses. These results support an aggressive attitude toward the use of revascularization in the operative treatment of such patients with renovascular hypertension, even when the residual excretory function is minimal or absent.

Adult↗
PubMed1978

Effects of caffeine on plasma renin activity, catecholamines and blood pressure.

Using a double-blind, randomized, cross-over protocol, we studied the effect of a single dose of oral caffeine on plasma renin activity, catecholamines and cardiovascular control in nine healthy, young, non-coffee drinkers maintained in sodium balance throughout the study period. Caffeine (250 mg) or placebo was administered in a methylxanthine-free beverage to overnight-fasted supine subjects who had had no coffee, tea or cola in the previous three weeks. Caffeine increased plasma renin activity by 57 per cent, plasma norepinephrine by 75 per cent and plasma epinephrine by 207 per cent. Urinary normetanephrine and metanephrine were increased 52 per cent and 100 per cent respectively. Mean blood pressure rose 14/10 mm Hg one hour after caffeine ingestion. There was a slight fall and then a rise in heart rate. Plasma caffeine levels were usually maximal one hour after ingestion but there was considerable individual variation. A 20 per cent increase in respiratory rate correlated well with plasma caffeine levels. Under the conditions of study caffeine was a potent stimulator of plasma renin activity and adrenomedullary secretion. Whether habitual ingestion has similar effects remains to be determined.

Administration, Oral↗