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Biomedical subjects

S Martin

Publications and source records attributed to S Martin.

At least 505 records · Page 28Linked to original sources
PubMed1990

Identification and characterization of glucose transport proteins in plasma membrane- and Golgi vesicle-enriched fractions prepared from lactating rat mammary gland.

Plasma membrane- and Golgi vesicle-enriched membrane fractions were prepared from day-10 lactating rat mammary glands. Each fraction was found to contain a single set of D-glucose-inhibitable cytochalasin B-binding sites: plasma membranes and Golgi vesicles bound 20 +/- 2 and 53 +/- 4 pmol of cytochalasin/mg of membrane protein (means +/- S.E.M.), with dissociation constants of 259 +/- 47 and 520 +/- 47 nM respectively. Anti-peptide antibodies against the C-terminal region (residues 477-492) of the rat brain/human erythrocyte glucose transporter labelled a sharp band of apparent Mr 50,000 on Western blots of both fractions. Treatment with endoglycosidase F before blotting decreased the apparent Mr of this band to 38,000, indicating that it corresponded to a glycoprotein. Confirmation that this immunologically cross-reactive band was a glucose transporter was provided by the demonstration that it could be photoaffinity-labelled, in a D-glucose-sensitive fashion, with cytochalasin B. Quantitative Western blotting studies yielded values of 28 +/- 5 and 23 +/- 3 pmol of immunologically cross-reactive glucose transporters/mg of membrane protein in the plasma membrane and Golgi vesicle fractions respectively. From comparison with the concentration of cytochalasin B-binding sites, it is concluded that a protein homologous to the rat brain glucose transporter constitutes the major glucose transport species in the plasma membranes of mammary gland epithelial cells. Glucose transporters are also found in the Golgi membranes of these cells, at least half of them being similar, if not identical, to the transporters of the plasma membrane. However, their function in this location remains unclear.

Animals↗
PubMed1990

Cellular stress induces a redistribution of the glucose transporter.

The mechanism by which cells increase their rate of glucose uptake in response to stress is unclear. Using an immunofluorescence technique to localize the glucose transporter protein in BHK cells, we found that hyperthermia, treatment with arsenite, infection with vesicular stomatitis virus or Semliki Forest virus, and treatment with insulin cause the transporter to move from an intracellular site in the perinuclear region to the plasma membrane; the degree of translocation correlates approximately with the increase in glucose uptake. We conclude that stress induces an insulin-like distribution of certain membrane proteins.

Animals↗
PubMed1990

Macroporous calcium phosphate ceramic for long bone surgery in humans and dogs. Clinical and histological study.

Our previous studies reported the performance of Macroporous Biphasic Calcium Phosphate (MBCP) in spine fusion. In the present study, this material was used in block forms in selected patients with tumoral resection in long bone. Two cases were chosen with large benign bone tumors. Clinical and radiographic assessments, CT scans, and NMR were performed after 16 months, and in one case control biopsies were taken. In order to understand the kinetic process of biodegradation of the MBCP blocks and bone formation at the expense of the ceramics, an experimental study in surgically created bond defects in canine femoral cortices was made. The MBCP blocks recovered after implantation period from 2 to 18 weeks were analyzed using histological, stereological, ultrastructural, electron microprobe, and IR spectroscopy analyses. This study demonstrated the efficiency of MBCP blocks for filling pathological defects in human long bone. The biointegration process of the MBCP blocks was due to a partial dissolution of the ceramics crystals (b-TCP content) by multinucleated cells. Simultaneously, bone ingrowth at the expense of the ceramic is observed. The new bone formation inside the MBCP macropores and in the spaces between the blocks, involved the formation of a new cortical bone on the outer part, and a trabecularlike bone with bone marrow in the inner part of the implant. The biological resorption of the MBCP ceramic decreased after 1 month implantation in dog, due to the protective role of the newly formed lamellar bone on the surface and in the core of the ceramics.

Animals↗
PubMed1990

Functional and morphological effects of interleukin-1 beta on the perfused rat pancreas.

We recently reported a potentiating effect of recombinant human interleukin-1 beta on glucose-stimulated insulin release from the isolated perfused pancreas. With the aim of determining whether the stimulatory effect of recombinant interleukin-1 beta on the B cell in the intact gland was modulated by varying the concentration, time of exposure to recombinant interleukin-1 beta or B-cell activity, and to elucidate a possible mechanism of action, we measured in the perfused rat pancreas the release of insulin, glucagon and/or prostaglandin E2 according to the following three different protocols: (1) perfusion with 20 ng/ml of recombinant interleukin-1 beta for 92 min at 5 and 20 mmol/l D-glucose (2) perfusion with varying concentrations of recombinant interleukin-1 beta ranging from 0.1 x 10(-3) ng/ml to 100 ng/ml at 5 and 20 mmol/l D-glucose (3) perfusion with 20 ng/ml of recombinant interleukin-1 beta at 5, 11 or 20 mmol/l D-glucose. Furthermore, in a separate set of experiments we examined the influence of the cytokine on the morphology of the endocrine pancreas. Interleukin-1 beta stimulated insulin secretion at 11 and 20 mmol/l D-glucose and potentiated first as well as second phase insulin release in a dose-dependent fashion, with decreasing effect at higher concentrations. Glucagon secretion was also stimulated by recombinant interleukin-1 beta, irrespective of increasing glucose (5, 11, 20 mmol/l) and insulin concentrations. The potentiating effect of recombinant interleukin-1 beta on insulin secretion was evident even after discontinued perfusion with the cytokine, suggesting a priming effect on B-cell function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Comparison of serologic and biochemical definitions of HLA class I polymorphisms in cadaver renal transplantation.

The role of biochemical variants in matching renal donors with recipients was investigated in a population of 26 donor recipient pairs from the period 1979-85. Serologic typing was compared with a biochemical analysis of HLA-A and -B antigens in a group in which there had been no mismatches for HLA-A and -B antigens by serology. HLA-A and -B serology was updated using stored material for 92.2% of the renal recipients and donors (n = 51), and HLA-A, -B, and -DR serology was updated for 84.3%. No inconsistencies were found with the HLA-A and -B antigens assigned at the time of transplant. HLA-A and -B antigens of 70% of the renal recipients and donors were analyzed by immunoprecipitation from lymphocytes and serum and analyzed after isoelectric focusing by autoradiography and Western blotting. No biochemical differences between recipient and donor were found for any one pair when HLA-A and -B antigens were serologically the same. This biochemical analysis was useful in providing results where there was doubt over the presence or absence of an antigen serologically. In a well-matched situation, HLA-A and -B serologic types were concordant with results obtained biochemically. However, in a poorly matched situation this could be different.

Antibodies, Monoclonal↗