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Biomedical subjects

D Pleasure

Publications and source records attributed to D Pleasure.

At least 127 records · Page 7Linked to original sources
PubMed1984

Metabolism of 15NH3 in organotypic cerebellar explants and cultured astrocytes: studies with gas chromatography-mass spectrometry.

Gas chromatography-mass spectrometry was used to study the metabolism of 15NH3 in organotypic cerebellar explants and cultured astrocyte monolayers. A steady-state level of 15NH3 was present by 1 min in both systems. Steady-state labeling in L-[amide-15N] glutamine, L-[15N]alanine, L-[15N]glutamate, and L-[15N]aspartate was attained by 1 min after 15NH3 addition in the organotypic cerebellar explants and by approximately 5 min in the cultured astrocytes. No measurable 15N labeling was noted in either glycine or serine in either system.

Ammonia↗
PubMed1983

Specific and potent mitogenic effect of axolemmal fraction on Schwann cells from rat sciatic nerves in serum-containing and defined media.

Using cultures of Schwann cells from neonatal rat sciatic nerves, we examined the mitogenic activity of an axolemmal fraction from adult rat CNS. Axolemmal fraction proved a potent mitogen, stimulating [3H]thymidine incorporation into Schwann cell DNA 13.5-fold over control values when axolemmal fraction equivalent to 16 micrograms of protein per culture microwell or more was added. Half maximal stimulation was obtained with addition of axolemmal fraction equivalent to 4 micrograms of protein. The concentration-dependence and magnitude of the mitogenic response of the cultured cells were nearly identical whether they were maintained in vitro for 1 day or for 2 weeks prior to addition of the axolemmal fraction. A study of the time-course of the effect of axolemmal fraction on Schwann cell mitosis showed that maximal [3H]thymidine incorporation took place during the fifth day after addition of axolemmal fraction. Axolemmal fraction also produced stimulation of [3H]thymidine incorporation into Schwann cells, seeded and cultured in a serum-free defined medium. Though the concentration-dependence of the mitogenic effect in the absence of serum was similar to that in a serum-containing medium, maximal stimulation in the defined medium was only 2.8-fold. The mitogenic activity of axolemmal fraction was rapidly and almost totally inactivated by sonication or homogenization, and was partially lost after exposure to heat. The mitogenic activities of plasma membrane fragments from rat skeletal muscle or rat erythrocytes, and of mitochondrial fragments (the major contaminant of the axolemmal fraction) were one-tenth that of axolemmal fraction or less. In contrast to glial growth factor prepared from bovine pituitaries (GGF-BP), which stimulates proliferation of both fibroblasts and Schwann cells, axolemmal fraction induced proliferation of Schwann cells but not of endoneurial fibroblasts; cultures treated with axolemmal fraction demonstrated a 3-fold increase in Schwann cell population in 10 days without detectable increase in number of fibroblasts. Also in contrast to GGF-BP, the mitogenic effect of which is considerably enhanced by simultaneous addition of cholera toxin to the medium, cholera toxin had no effect on the Schwann cell proliferative response to axolemmal fraction.

Animals↗
PubMed1983

[15N] leucine as a source of [15N] glutamate in organotypic cerebellar explants.

Approximately 26.0% of the [15N] glutamate and [alpha 15N] glutamine formed in organotypic cerebellar explants was derived from [15N] leucine. Approximately 14.0% of the 15NH3 and [amide 15N] glutamine synthesized came from leucine nitrogen. Another 4.0% of the alpha nitrogen of both glutamate and glutamine was derived from [15N] valine. These results suggest that branched-chain amino acids, particularly leucine, may be important for the synthesis of glutamic acid by the brain.

Amino Acids↗
PubMed1983

Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome.

We describe seven adults who had ataxia and severe sensory-nervous-system dysfunction after daily high-level pyridoxine (vitamin B6) consumption. Four were severely disabled; all improved after withdrawal. Weakness was not a feature of this condition, and the central nervous system was clinically spared. Although consumption of large doses of pyridoxine has gained wide public acceptance, this report indicates that it can cause sensory neuropathy or neuronopathy syndromes and that safe guidelines should be established for the use of this widely abused vitamin.

Adult↗
PubMed1983

Long-term culture of oligodendrocytes isolated from rat corpus callosum by Percoll density gradient. Lysis by polyclonal antigalactocerebroside serum.

Oligodendrocytes isolated from the corpus callosum of four-week-old rats by trypsimization and Percoll density gradient centrifugation were cultured on poly-1-lysine coated coverslips. Some cells extended short processes within 24 hours (h), and at that time up to 95% of the cells showed surface binding of rabbit antiserum to galactocerebroside (anti-GalC) as demonstrated by indirect immunofluorescence. Oligodendrocytes survived up to two months in culture, extending processes with membranous elaborations. Exposure of living oligodendrocytes to varying dilutions of rabbit anti-GalC serum in the presence of complement produced cytotoxicity which was directly proportional to the concentration of antiserum and duration of exposure, as assessed by a nigrosin dye exclusion test. This system of isolating and culturing rat oligodendrocytes will permit further developmental and immunologic studies related to demyelinating diseases.

Animals↗
PubMed1983

Peripheral nervous system myelin and Schwann cell glycoproteins: identification by lectin binding and partial purification of a peripheral nervous system myelin-specific 170,000 molecular weight glycoprotein.

Radioiodinated lectins were used to detect glycoproteins of peripheral nervous system (PNS) myelin (rat, human, bovine) and cultured rat Schwann cells. Proteins were resolved by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis and transferred to nitrocellulose filters. The filters were overlaid with radioiodinated lectins of known saccharide affinities. These included concanavalin A, Helix pomatia, Limulus polyphemus, Maclura pomifera, peanut, soybean, Ulex europaeus, and wheat germ agglutinins. Inclusion of the appropriate monosaccharide in the overlay solution (0.2 M) inhibited lectin binding to the nitrocellulose-fixed proteins. Fluorography permitted identification of 26 myelin glycoproteins and many more in Schwann cells. All lectins labeled a band present in myelin, but not Schwann cells, corresponding to the major PNS myelin protein, P0. Our attention focused on a high-molecular-weight myelin glycoprotein [apparent molecular weight (Mr) 170,000], which appeared abundant by Coomassie Blue staining and which was heavily labeled by all lectins except concanavalin A. A protein with approximately this Mr and lectin-binding pattern was present in human and bovine PNS myelin as well, but not detected in rat Schwann cells, CNS myelin, liver and fibroblast homogenates, or cultured bovine oligodendroglia. Hence this 170,000 Mr glycoprotein is apparently unique to PNS myelin.

Animals↗
PubMed1983

CSF antibodies to myelin basic protein and oligodendrocytes in multiple sclerosis and other neurological diseases.

Cerebrospinal fluid (CSF) from 18 multiple sclerosis (MS) patients, 13 subacute sclerosing panencephalitis (SSPE) patients, 22 other neurological disease (OND) patients, and 7 neurotic patients as controls were tested in an 125I-labeled anti-human F(ab')2 binding assay for the presence of antibodies to normal human brain cells from tissue culture, human fibroblasts, plasma membranes of MS and normal human brain, myelin basic protein (MBP) and bovine oligodendrocytes. Antibodies to MBP and to oligodendrocytes were found in the CSF of MS, SSPE and OND patients. Absorption of CSF with bovine CNS myelin significantly diminished binding activity to oligodendrocytes. Antibodies in the CSF against MBP and oligodendrocytes, on which some myelin determinants are expressed, seem to be a common feature of diseases in which demyelination is a component.

Antibodies↗
PubMed1982

Oligoclonal IgG in the cerebrospinal fluid of guinea pigs with acute experimental allergic encephalomyelitis.

The cerebrospinal fluid (CSF) of guniea pigs with experimental allergic encephalomyelitis was examined for the presence of oligoclonal IgG using polyacrylamide gel electrophoresis. Oligoclonal IgG (greater than or equal to 2 bands) was seen in the CSF obtained from 3/4 animals with experimental allergic encephalomyelitis induced by myelin basic protein and 2/3 with spinal cord-induced disease. It was not seen in CSF of 3 non-sensitized, 4 adjuvant-sensitized and 7 liver-sensitized guinea pigs. Scanning of stained gels confirmed the oligoclonal pattern. The bands were found in the region of gels which bound [125I]Staphylococcal Protein A. The data demonstrate that a non-infectious inflammatory reaction within the central nervous system can result in an oligoclonal IgG pattern in the CSF.

Animals↗
PubMed1981

Oligodendroglial glycerophospholipid synthesis: incorporation of radioactive precursors into ethanolamine glycerophospholipids by calf oligodendroglia prepared by a Percoll procedure and maintained in suspension culture.

Oligodendroglia prepared from minced calf cerebral white matter by trypsinization at pH 7.4, screening, and isosmotic Percoll (polyvinylpyrolidone-coated silica gel) density gradient centrifugation survived in culture on polylysine-coated glass, extending processes and maintaining phenotypic characteristics of oligodendroglia. In the present study, ethanolamine glycerophospholipid (EGP) metabolism of the freshly isolated cells was examined during short-term suspension culture by dual label time course and substrate concentration dependence experiments with [2-3H]glycerol and either [1,2-14C]ethanolamine or L-[U-14C]serine. Rates of incorporation of 3H from the glycerol and of 14C from the ethanolamine into EGP were constant for 14 h. In medium containing 3 mM-[1,2-14C]ethanolamine and 4.8 mM-[2-3H]glycerol, rates of incorporation of 14C and 3H into diacyl glycerophosphoethanolamine (diacyl GPE) were similar. Under the same conditions, 3H specific activities of alkylacyl GPE and alkenylacyl GPE were much lower than 14C specific activities, likely as a result of the loss of tritium during synthesis of these forms of EGP via dihydroxyacetone phosphate. L-[U-14C]serine was incorporated into serine glycerophospholipid (SGP) by base exchange rather than de novo synthesis. 14C from L-[U-14C]serine also appeared in EGP after an initial lag period of several hours. Methylation of oligodendroglial EGP to choline glycerophospholipid (CGP) was not detected.

Animals↗
PubMed1979

Immune response to isolated oligodendrocytes.

Oligodendrocytes were isolated from bovine white matter and were injected with complete Freund's adjuvant (CFA) into experimental animals. Indirect immunofluorescence studies using fluoresceinated goat anti-rabbit or anti-guinea pig immunoglobulin (GARIg; GAGPIg) showed that rabbit and guinea pig anti-oligodendrocyte (RAO, GPAO) sera reacted specifically with the surface of isolated oligodendrocytes in suspension, as well as with oligodendroglia in bovine and human brain sections, and in mouse cerebellum cultures. This activity of RAO was blocked by non-fluoresceinated GARIg and by GPAO, and absorbed by oligodendrocyte preparation (OP) or whole white matter, but not by purified myelin, neuroblastoma or non-brain tissue. Low levels of anti-basic protein antibodies were found in many RAO (but not GPAO) sera by radioimmunoassay, and a few showed significant anti-galactocerebroside antibody by agglutination and radioimmunoprecipation techniques. Guinea pigs sensitized with isolated oligodendrocytes in CFA showed cell-mediated immunity (CMI) to OP as manifested by delayed type skin test and induced in vitro lymphocyte transformation. CMI to purified myelin basic protein was not detected. The demonstration of humoral and CMI to the cell responsible for the production of CNS myelin may be related to some aspects of the immunopathogenesis of demyelinating disorders.

Animals↗
PubMed1979

Skeletal muscle calcium metabolism and contractile force in vitamin D-deficient chicks.

The myopathy associated with vitamin D deficiency has not been well characterized, and it is not known if weakness is a result of a specific effect of vitamin D deficiency on skeletal muscle. Chicks were raised from hatching on a vitamin D-deficient diet, and by 3 wk of age were hypocalcemic and appeared weak. Tension generated by triceps surae during repetitive stimulation of posterior tibial nerve was significantly less than that developed by chicks given vitamin D(3) supplements (309 g tension/g wet weight of triceps surae, SD 60, for vitamin D-deficient chicks; 470, SD 77, for vitamin D(3)-treated chicks, P < 0.01). Histochemical and electron microscopic examination of skeletal muscles of these chicks showed no abnormalities, and there were no electrophysiologic evidences of motor nerve or neuromuscular junction dysfunction. The concentration of ATP in skeletal muscle of the vitamin D-deficient chicks (5.75 mumol/g wet weight, SD 0.17) was not significantly different from that in vitamin D-treated chicks (5.60, SD 0.50). There was no correlation between strength and serum calcium, serum inorganic phosphate, or skeletal muscle inorganic phosphate. Relaxation of tension after tetanic stimulation was slowed in the vitamin D-deficient chicks (20.6 ms, SD 1.7, vs. 15.4, SD 1.3, in vitamin D-treated chicks and 15.3, SD 1.0, in normal control chicks), and in vitro (45)Ca(++) transport by sarcoplasmic reticulum from the vitamin D-deficient chicks was reduced. Calcium content of mitochondria prepared from leg muscles of vitamin D-deficient chicks (24 nmol/mg mitochondrial protein, SD 6) was considerably lower than that of mitochondria from normal control chicks (45, SD 8) or from chicks treated with vitamin D for 2 wk or more (66-100, depending upon level and duration of therapy). Treatment of the vitamin D-deficient chicks from hatching with sufficient dietary calcium to produce hypercalcemia did not significantly raise skeletal muscle mitochondrial calcium content (31 nmol/mg mitochondrial protein, SD 7) and did not prevent weakness. These studies demonstrate objective weakness as a result of myopathy in vitamin D-deficient chicks, and provide evidence that vitamin D deficiency has effects on skeletal muscle calcium metabolism not secondary to altered plasma concentrations of calcium and phosphate.

Animals↗
PubMed1979

Freeze-fracture studies of erythrocyte plasma membrane in human neuromuscular diseases.

Freeze-fracture studies were conducted in erythrocyte plasma membrane from 8 patients with Duchenne muscular dystrophy (DMD), 8 age-matched controls, 3 adult controls, 10 patients with myotonic muscular dystrophy, and 26 other neuromuscular disease controls. There was marked depletion of intramembranous particles in Duchenne dystrophy, whereas intramembranous particle density counts in other neuromuscular diseases were within normal limits. Therefore, the internal molecular architecture of the erythrocyte membrane is abnormal in Duchenne dystrophy, supporting the concept that a membrane defect involving multiple tissues is present in this disorder.

Erythrocyte Membrane↗
PubMed1978

Alteration in erythrocyte membrane structure in Duchenne muscular dystrophy.

Freeze-fracture studies of erythrocytes from patients with Duchenne muscular dystrophy revealed depletion of particles on both fracture faces of the plasma membrane. This study indicates that the structure of the erythrocyte plasma membrane is abnormal in Duchenne dystrophy and supports the concept that a generalized membrane abnormality is present in this disease.

Adolescent↗