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Biomedical subjects

S A Kahn

Publications and source records attributed to S A Kahn.

9 recordsLinked to original sources
PubMed1997

Contribution of endothelin-1 to renal vasoconstriction in unilateral ureteral obstruction: reversal by verapamil.

PURPOSE: In unilateral ureteral obstruction (UUO) vasoconstriction occurs both during and after release of UUO. ET-1, an endogenous peptide, causes marked vasoconstriction mediated by an increase in cytosolic calcium. We measured renal output of endothelin-1 (ET-1) in dogs with UUO and examined if the renal vasoconstriction that persisted after release of UUO could be reversed by a calcium antagonist, verapamil. MATERIALS AND METHODS: Hemodynamic and clearance experiments were performed in anesthetized mongrel dogs in three groups. Group I consisted of 9 dogs with sham-operation. Group 2 consisted of 7 dogs in whom ureteral obstruction was released 1.9 hours after UUO. Group 3 consisted of 5 dogs in whom verapamil was infused into the renal artery at two doses (5 and 10 microg./min., respectively) after release of UUO of 19-hour duration. ET-1 concentrations (measured by radioimmunoassay) were determined for renal venous and arterial plasma. RESULTS: In Group 1 renal venous plasma ET-1 level was 16.7 +/- 2.2, significantly lowered than 22.8 +/- 3.2 pg./ml. in arterial plasma, indicating a net clearance of ET-1. In Group 2 and 3, renal venous plasma ET-1 levels (28.2 +/- 5.2 and 27.2 +/- 2.4 pg./ml., respectively) were significantly greater than those in arterial plasma (24.2 +/- 5.7 and 17.4 +/- 0.8 pg./ml., respectively), indicating a net output of ET-1 in the kidney, In addition, renal vasoconstriction occurred in Groups 2 and 3 as indicated by significantly lower renal blood flow and GFR than those in Group 1. In Group 3, intrarenal infusion of verapamil at two doses did not change arterial pressure but caused an ipsilateral, significant increase in RBF (from 132 +/- 4 17 to 1.84 +/- 19 and 180 +/- 16 ml./min., respectively) and dose-dependent increases in GFR (from 12 +/- 2 to 25 +/- 3 and 38 +/- 7 ml./min., respectively), associated with a profound dose-dependent ipsilateral diuresis and natriuresis. CONCLUSION: Profound renal vasoconstriction in UUO was associated with an increase in renal production of ET-1, possibly contributing to renal vasoconstriction, and was reversed by intrarenal infusion of verapamil.

Animals↗
PubMed1994

Osteoporosis and genetic influence: a three-generation study.

We have studied 27 triads of mother, daughter and grandmother for possible genetic influence on distal and proximal forearm bone density, measured by single photon absorptiometry. We found a significant correlation of bone density at the proximal forearm between the mothers and grandmothers (r = 0.499, P < 0.01). There was also a weak correlation between proximal forearm bone densities of mothers and daughters (r = 0.327, P < 0.1). Significant correlations were found between the three generations for grip strength, pedometry, height and triceps skinfold thickness. There was also significant correlation between mother and grandmother for alcohol intake. There was no correlation for contraceptive pill use, smoking, dietary calcium intake, body weight or body mass index. The study concludes that, although there are similarities in bone mineral content between the three generations, genetic factors cannot be conclusively proven to be the major determinant of bone density. Lifestyle and environmental factors may have a bearing on achieving the peak bone mass and subsequent development of osteoporosis.

Absorptiometry, Photon↗
PubMed1986

Hepatic disorders in the acquired immune deficiency syndrome: a clinical and pathological study.

We reviewed the clinical data, hepatic histology, and microbiological features of 21 patients with previously documented acquired immune deficiency syndrome who had liver biopsies. Diagnoses of specific infections were made on liver biopsy in 11/21 patients (57%). Granulomas were found in 10/21 patients (48%) and were most often a manifestation of infection with Mycobacterium avium-intracellulare. Elevated levels of serum alkaline phosphatase and longer duration of diagnosed illness were significantly associated with the presence of granulomatous disease.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Local area networks and the hospital.

Hospital information systems are characterized by their complexity of individual functions, heterogeneity of functions, and dependence upon integration. A distributed computerized information system is well suited to meeting the needs of hospitals. A local area communications network (LACN) removes a major impediment to the use of distributed systems. An advanced microprocessor-based LACN using fiberoptic communications has been developed by the Applied Physics Laboratory of The Johns Hopkins University and has been implemented at the University of California, San Francisco Hospital.

California↗
PubMed1982

A prototype generalized network technology for hospitals: initial implementation.

A demonstration implementation of a distributed data-processing hospital information system using an intelligent local area communications network (LACN) technology is described. This system is operational at the UCSF Medical Center and integrates four heterogeneous, stand-alone minicomputers. The applications systems are PID/Registration, Outpatient Pharmacy, Clinical Laboratory, and Radiology/Medical Records. Functional autonomy of these systems has been maintained, and no operating system changes have been required. The LACN uses a fiber-optic communications medium and provides extensive communications protocol support within the network, based on the ISO/OSI Model. The architecture is reconfigurable and expandable. This paper describes system architectural issues, the applications environment, and the local area network.

California↗