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Biomedical subjects

G M Gray

Publications and source records attributed to G M Gray.

At least 55 records · Page 3Linked to original sources
PubMed1985

Abrupt induction of a membrane digestive enzyme by its intraintestinal substrate.

The regulation of amino-oligopeptidase (AOP), an intestinal brush border hydrolase essential for the surface digestion of peptide nutrients, was examined in rats in vivo. Short-term (30-minute) intraintestinal perfusion of a tetrapeptide substrate, Gly-Leu-Gly-Gly, or a synthetic substrate, leucyl-beta-naphthylamide, induced a doubling in the incorporation of [3H]leucine into the AOP in association with intracellular membranes. The subsequent conversion of AOP from nascent to mature enzyme and its membrane-associated transport to the brush border occurred at normal rates.

Aminopeptidases↗
PubMed1985

Complex subcellular distributions of enzymatic markers in intestinal epithelial cells.

Current procedures for isolating intestinal epithelial cell surface and intracellular membranes are based on the assumption that each organelle is marked by some unique constituent. This assumption seemed inconsistent with the dynamic picture of subcellular organization emerging from studies of membrane turnover and recycling. Therefore, we have designed an alternative fractionation which is independent of a priori marker assignments. We subjected mucosal homogenates to a sequence of separations based on sedimentation coefficient, equilibrium density, and partitioning in aqueous polymer two-phase systems. The resulting distributions of protein and enzymatic markers define a total of 17 physically and biochemically distinct membrane populations. Among these are: basal-lateral membranes, with Na,K-ATPase enriched 21-fold; brush-border membranes, with alkaline phosphatase enriched as much as 38-fold; two populations apparently derived from the endoplasmic reticulum; a series of five populations believed to have been derived from the Golgi complex; and a series of five acid phosphatase-rich populations which we cannot identify unequivocally. Each of the five enzymatic markers we have followed is associated with a multiplicity of membrane populations. Basallateral, endoplasmic reticulum, and Golgi membranes contain alkaline phosphatase at the same specific activity as the initial homogenate. Similarly, Na,K-ATPase appears to be associated with Golgi, endoplasmic reticulum, and brush-border membranes at specific activities two- to seven-fold that of the initial homogenate.

Acid Phosphatase↗
PubMed1983

Breast disease in young women. When is biopsy indicated?

The low incidence of breast cancer among women under the age of 25 years may not justify the routine excision biopsy of breast lumps in this age group. A policy of conservative management has been tested in 70 women between the ages of 17 and 25 years. Excision biopsy was eventually performed in 23 women - fewer than half of those with a palpable mass. No cancerous lesions were found; a high proportion of lumps removed were fibroadenomas. The accuracy of clinical diagnosis was high and, of 31 breast lumps diagnosed as benign mammary dysplasia, more than three-quarters resolved without surgical intervention. Indications for surgery are defined. Because breast cancer does occasionally occur in this age group, accurate clinical diagnosis and review are essential components of conservative management.

Adenofibroma↗
PubMed1983

Basal-lateral and intracellular membrane populations of rat exorbital lacrimal gland.

With the goal of isolating and identifying plasma membrane vesicle populations from epithelial cells of the rat exorbital lacrimal gland, we have designed an analytical fractionation of homogenates of the gland parenchyma. This fractionation utilizes separation procedures based on three independent physical properties of subcellular particles: sedimentation coefficient, density, and density after interaction of membrane cholesterol with digitonin. A commonly accepted marker for basal-lateral membranes, Na-K-ATPase, is associated with at least two physically distinct membrane populations. One population can be identified as basal-lateral membrane fragments on the basis of its fractional and specific contents of Na-K-ATPase; it accounts for 50% of the total Na-K-ATPase activity, enriched 29-fold with respect to the initial homogenate. With these values we calculate that the sample of basal membranes has been purified 60-fold with respect to the initial homogenate. The remaining Na-K-ATPase activity appears to be associated, at three- to fivefold lower specific activities, with intracellular membrane populations. We speculate that these populations have been derived from the Golgi complex.

Alkaline Phosphatase↗
PubMed1983

Location and activity of ulcerative and Crohn's colitis by indium 111 leukocyte scan. A prospective comparison study.

A prospective blinded study comparing the indium 111 leukocyte scan to barium enema, colonoscopy, or surgery or a combination of these, was carried out in 15 patients (10 with active ulcerative colitis and 5 with active Crohn's colitis). Correlation of disease location to colonic regions between indium scan and other diagnostic studies was excellent in 11 instances, good in 2, and poor in 3. In 2 of the 3 studies where major disagreement occurred, the comparative barium enema was performed greater than 2 mo after the indium scan. Disease activity, estimated by the intensity of radionuclide uptake, was compared to clinical disease activity assessed by the Crohn's Disease Activity Index for both forms of colitis. The relative degree of inflammation estimated by the indium scan correlated well with the independent clinical assessment (correlation coefficient = 0.81). The indium 111 leukocyte scan appears to be an accurate, noninvasive method for assessing the extent and the severity of the inflammation in patients with acute ulcerative or Crohn's colitis.

Adolescent↗
PubMed1982

Lipid composition of the superficial stratum corneum cells of pig epidermis.

Stratum corneum was removed from the surface of pig skin using a wet brushing technique. The material so obtained was fractionated into cell clumps, discrete cells and fine material by differential filtration through nylon gauzes. Ceramide, cholesterol and free fatty acid accounted for about 95% of the lipid present in each fraction: phospholipid and glycolipid were not detected. Material removed by successive brushings showed no detectable differences in lipid composition.

Animals↗
PubMed1981

Intestinal diffusion barrier: unstirred water layer or membrane surface mucous coat?

The dimensions of the small intestinal diffusion barrier interposed between luminal nutrients and their membrane receptors were determined from kinetic analysis of substrate hydrolysis by integral surface membrane enzymes. The calculated equivalent thickness of the unstirred water layer was too large to be compatible with the known dimensions of rat intestine. The discrepancy could be reconciled by consideration of the mucous coat overlying the intestinal surface membrane. Integral surface membrane proteins could not be labeled by an iodine-125 probe unless the surface coat was first removed. The mucoprotein surface coat appears to constitute an important diffusion barrier for nutrients seeking their digestive and transport sites on the outer intestinal membrane.

Animals↗
PubMed1980

The plasma membrane of Malpighian cells from pig epidermis: isolation and lipid and protein composition.

A plasma membrane fraction from Malpighian cells has been isolated by differential and density gradient centrifugation of a pig epidermal homogenate. It was enriched in the marker enzymes 2-naphthylamidase, 5'-nucleotidase, phosphodiesterase I and acid phosphatase and depleted of NADH-ferricyanide reductase and cytochrome c oxidase. It had a protein to lipid ratio of 3:2 by weight. The protein composition was complex with compounds ranging from a molecular weight of 150,000 down to 13,000. Major components with molecular weights 120,000 to 90,000 were glycoproteins. Two other components had molecular weights of 39,000 (actin ?) and 24,000. There were minor components with molecular weights from 63,000 to 46,000. About 76% of the total lipid was present as phospholipid, which was enriched in sphingomyelin. Most of the neutral lipids were accounted for by cholesterol, triacylglycerols and fatty acids: very little glycosphingolipid was present. The preparation was probably derived from non-desmosomal areas of the plasma membrane of Malpighian cells, as desmosomes were not seen in the preparation.

Animals↗
PubMed1980

Distribution of glycoproteins containing fucose in normal and psoriatic keratinocytes.

Electron microscope autoradiography has been used to compare the fucose-containing glycoproteins of normal and psoriatic epidermis. Normal keratinocytes and uninvolved psoriatic cells have most of their fucose on the plasma membrane, whereas involved psoriatic cells retain more within the cytoplasm. The fucose distribution in other epidermal cell types is also described.

Autoradiography↗