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Biomedical subjects

J S Davis

Publications and source records attributed to J S Davis.

At least 181 records · Page 10Linked to original sources
PubMed1976

Avascular necrosis in SLE. An apparent predilection for young patients.

Recent reports of avascular necrosis (AN) in systemic lupus erythematosus (SLE) have suggested that its occurrence may be most frequent in young patients. In our population of 99 patients with SLE, 7 young patients have developed AN. Patterns of prednisone therapy had no apparent relationship to the development of AN. AN may become apparent in patients who have relatively inactive lupus, when increased physical activity precipitates articular collapse. A diagnosis of AN should be considered in young patients with localized joint pain.

Adolescent↗
PubMed1975

Extracellular glomerular microparticles in nephrotic syndrome of heroin users.

Intracellular and extracellular glomerular microparticles (GMP) have been described in diverse human glomerulopathies. We have recently detected extracellular GMP in two heroin abusers with nephrotic syndrome. Most of the GMP were approximately 100 nm in diameter (range, 56 to 178 nm), and consisted ultrastructurally of an electron-dense central core surrounded by a concentric, lucent area and an electron-dense limiting membrane. Incomplete forms of GMP and residual laminated membranes without a central core were also present. The distribution of extracellular GMP was both intramembranous and subepithelial; they did not resemble virions morphologically. As these GMP have been observed in human glomerulopathies that are etiologically and morphologically varied, they probably represent nonspecific markers of glomerular injury. The prevalence of GMP in the nephrotic syndrome of heroin abusers awaits cumulative experience.

Adult↗
PubMed1973

Assay, purification, properties and mechanism of action of gamma-glutamylcysteine synthetase from the liver of the rat and Xenopus laevis.

1. An improved radioassay for glutathione synthetase and gamma-glutamylcysteine synthetase was developed. 2. Xenopus laevis liver gamma-glutamylcysteine synthetase was purified 324-fold by saline-bicarbonate extraction, protamine sulphate precipitation, CM-cellulose and DEAE-cellulose column chromatography, and gel filtration. 3. Rat liver gamma-glutamylcysteine synthetase was purified 11400-fold by a procedure similar to that employed for the Xenopus laevis enzyme. 4. Rat liver gamma-glutamylcysteine synthetase activity was inhibited by GSH and activated by glycine. These effects, which were not found in the enzyme from Xenopus laevis, may have a regulatory significance. 5. Isotope-exchange experiments revealed fundamental differences in the partial reactions catalysed by the rat and Xenopus laevis synthetases. The enzyme from Xenopus laevis appears to follow a Bi Bi Uni Uni Ping Pong mechanism, with glutamyl-enzyme as intermediate before the addition of cysteine and the release of gamma-glutamylcysteine. The results for the rat liver enzyme are consistent with a Tri Tri sequential mechanism.

Animals↗