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Biomedical subjects

R M Zusman

Publications and source records attributed to R M Zusman.

72 records · Page 4Linked to original sources
PubMed1977

The treatment of the hepatorenal syndrome with intra-renal administration of prostaglandin E1.

Three patients with the hepatorenal syndrome were treated with prostaglandin E1 administered through a selective renal arterial catheter. Prostaglandin E1 was given in progressively increasing doses (2 to 100 ng/kg/min) over a 60-minute period. Control plasma prostaglandin E levels were elevated in all three patients, 0.98, 0.91, and 0.83 ng/ml, respectively. At the end of the infusion, plasma prostaglandin E levels had risen to 10.4, 2.63, and 10.3 ng/ml in the three patients respectively. Plasma renin activity increased during the course of the infusion in two of the patients. The plasma aldosterone concentration did not change during the prostaglandin E1 infusion. Intrarenal prostaglandin E1 failed to increase urine volume or urinary sodium concentration in three patients with the hepatorenal syndrome.

Adult↗
PubMed1977

Prostaglandin biosynthesis by rabbit renomedullary interstitial cells in tissue culture. Stimulation by angiotensin II, bradykinin, and arginine vasopressin.

Rabbit renomedullary interstitial cells were isolated and grown in tissue culture. These cells synthesize 0.8 ng of prostaglandin E2 (PGE2) per microgram cellular protein per hour in monolayer tissue culture; prostaglandins A2 and F2alpha (PGA2 and PGF2alpha) biosynthesis was 10 and 5% of PGE2 biosynthesis, respectively. Arachidonic acid markedly stimulated the production of PGE2 and PGF2alpha, with conversion rates of 0.24 and 0.02%/h, respectively. Angiotensin II, hyperosmolality, bradykinin, and arginine vasopressin each stimulated PGE2 biosynthesis; maximum stimulation was 20, 3.7, 3.6, and 3.2 times basal production, respectively. PGE2 biosynthesis by the renomedullary interstitial cells was inhibited by isoproterenol, potassium, nonsteroidal anti-inflammatory agents (indomethacin, naproxen, ibuprofen, suprofen, meclofenamate, and acetylsalicylic acid), mepacrine (a phospholipase inhibitor), hydrocortisone, and cortisone. The rabbit renomedullary interstitial cell in tissue culture is a model system for the study of hormonal regulation of PGE2 biosynthesis.

Angiotensin II↗
PubMed1977

Vasopressin-stimulated prostaglandin E biosynthesis in the toad urinary bladder. Effect of water flow.

Prostaglandin E biosynthesis and its effect on water permeability were investigated in the toad urinary bladder. Arginine vasopressin (1 mU/ml) increased prostaglandin E (PGE) biosynthesis from 0.5+/-0.1 to 5.0+/-0.4 pmol/min per hemibladder (mean +/-SEM, n= 8, P less than 0.001). Maximal vasopressin-stimulated PGE biosynthesis, 6.4+/-0.2 pmol/min per hemibladder, occurred at vasopressin concentrations in excess of 3 mU/ml. Half-maximal stimulation of PGE biosynthesis occurred at a vasopressin concentration of approximately 0.7 mU/ml, whereas half-maximal stimulation of water flow occurred at a vasopressin concentration of approximately 5 mU/ml. Vasopressin-stimulated PGE biosynthesis did not depend on water flow along an osmotic gradient or upon sodium transport. Thin-layer chromatographic analysis of the lipids released from hemibladders labeled with tritium-arachidonic acid revealed that vasopressin stimulates the release of arachidonic acid from intracellular lipid stores without affecting the percentage of free arachidonic acid converted to PGE. Neither cyclic AMP nor theophylline stimulated PGE biosynthesis although they mimic arginine vasopressin (AVP) in stimulating water permeability. Biosynthesis of PGE was inhibited by mepacrine, a phospholipase inhibitor, and by agents that inhibit arachidonic acid oxygenase. The inhibition of PGE biosynthesis resulted in augmented vasopressin- and theophylline-stimulated water flow, but had no effect on cyclic AMP-stimulated water flow. We interpret these results to mean that endogenous PGE inhibits basal and vasopressin-stimulated adenylate cyclase activity. In contrast to the effects of AVP on permeability and transport, AVP stimulates PGE biosynthesis by a mechanism that does not depend on an increase in cellular cyclic AMP levels. The water permeability response of the toad urinary bladder to vasopressin is inhibited by PGE synthesized by the bladder in response to vasopressin.

Adenylyl Cyclases↗
PubMed1977

Inhibition of vasopressin-stimulated prostaglandin E biosynthesis by chlorpropamide in the toad urinary bladder. Mechanism of enhancement of vasopressin-stimulated water flow.

Chlorpropamide is known to enhance the water permeability response of the toad urinary bladder to vasopressin and to theophylline. In other studies, we have shown that prostaglandin E synthesis by the toad bladder inhibits the water permeability response to arginine vasopressin and to theophylline. In this study, the effect of chlorpropamide on vasopressin-, theophylline-, and cyclic AMP-stimulated water flow and on prostaglandin E biosynthesis was investigated in the toad urinary bladder in vitro. Chlorpropamide inhibited prostaglandin E biosynthesis during vasopressin-, theophylline- and cyclic AMP-stimulated water flow. Tolbutamide and glyburide, two other sulfonylurea compounds, also enhanced vasopressin-stimulated water flow and inhibited vasopressin-stimulated prostaglandin E biosynthesis. We conclude that the mechanism of enhancement on vasopressin-stimulated water flow by the sulfonylureas is the inhibition of prostaglandin E biosynthesis.

Animals↗
PubMed1977

Benign breast dysplasia causing hypercalcemia.

An adolescent female had hypercalcemia and massive, bilateral breast enlargement. At neck and mediastinal explorations three parathyroid glands were removed and found to be histologically normal. Following bilateral mastectomy the hypercalcemia resolved within two days and did not recur during a six-year period of followup. Microscopic examination of the excised breast tissue revealed marked dysplasia but no cancer. Those findings suggest that benign, dysplastic breast tissue can release humoral mediators of hypercalcemia.

Adolescent↗
PubMed1973

The effect of chronic sodium loading and sodium restriction on plasma prostaglandin A, E, and F concentrations in normal humans.

It has been suggested that prostaglandins may be involved in the control of sodium homeostasis. Prostaglandin A and prostaglandin E have been shown to increase renal blood flow and urinary sodium excretion and prostaglandin A has been shown to stimulate aldosterone release. The purpose of this study was to determine the effect of chronic sodium loading and sodium restriction on plasma prostaglandin A, E, and F concentrations. SEVEN NORMAL HUMAN VOLUNTEERS WERE PLACED ON THREE SODIUM INTAKE DIETS: (a) ad lib. sodium intake, (b) high sodium intake, and (c) low sodium intake. Plasma prostaglandin A, E, and F concentrations were measured by radioimmunoassay. Mean prostaglandin A levels on the ad lib. diet were 1.60 ng/ml. Prostaglandin A levels decreased 49% to 0.82 ng/ml on the high sodium intake and increased 34% to 2.14 ng/ml on the low sodium intake. Prostaglandin A levels increased 161% on the low sodium diet in comparison with levels on the high sodium diet. Plasma prostaglandin E and F concentrations did not change significantly during variation in sodium intake. These results show that dietary sodium content markedly effects plasma prostaglandin A levels and that prostaglandins may play a role in the physiologic mechanism of sodium homeostasis.

Adult↗
PubMedDate not supplied

Comparative evaluation of the three commercially available transdermal nitroglycerin delivery systems.

We comparatively evaluated the patient preference for each of the three commercially available transdermal nitroglycerin delivery systems using a randomized crossover study design. Preference was determined by ease of application, adhesion, occurrence of local irritation at the site of application, and systemic toxicities. In addition, we recorded the number of nitroglycerin tablets taken and angina attacks reported per treatment course. Each treatment course was one month long, with each patient participating for a total of three months. This allowed all patients to be exposed to each of the three products for one treatment course, thereby serving as their own controls. Thirty-eight patients completed the three-phase crossover and expressed a preference. Results showed that Transderm-Nitro was significantly preferred over both Nitro-Dur and Nitrodisc (p less than 0.005). Most of the preferences were based on cosmetic appearances or adhesive qualities. Additionally, results showed that there was no difference in efficacy among the three products when number of angina attacks reported and number of nitroglycerin tablets taken were compared.

Administration, Cutaneous↗
PubMedDate not supplied

The role of alpha 1-blockers in combination therapy for hypertension.

Antihypertensive monotherapy provides adequate blood pressure control in less than 50% of patients with hypertension (BP > 140/90 mmHg), especially those with stage 2-3 disease. This article reviews clinical studies that demonstrate that add-on therapy with an alpha1-blocker (doxazosin, terazosin or prazosin) is an effective and well-tolerated regimen for improving blood pressure control in patients with inadequately controlled hypertension. Furthermore, alpha1-blockers have therapeutic benefits that go beyond blood pressure management. They have a small but positive effect on the serum lipid profile and they have favourable or benign effects on conditions that frequently coexist with hypertension, such as type 2 diabetes mellitus and benign prostatic hyperplasia.

Adrenergic alpha-Antagonists↗