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Biomedical subjects

T H Oh

Publications and source records attributed to T H Oh.

At least 73 records · Page 4Linked to original sources
PubMed1980

Sciatin: purification and characterization of a myotrophic protein from chicken sciatic nerves.

A protein isolated from sciatic nerves of adult chickens promotes the morphological maturation and maintenance of embryonic avian skeletal muscle cells in the absence of innervation and is required for normal myogenesis in vitro. This trophic protein, sciatin, has been purified by ion exchange column chromatography on DEAE-cellulose followed by gel filtration on Sephadex G-100. Sciatin migrated as a single polypeptide chain of molecular weight 84,000 on sodium dodecyl sulfategel electrophoresis. The native molecular weight of sciatin as determined by sedimentation equilibrium centrifugation was 86,400. Amino acid analysis revealed that sciatin is relatively deficient in tryptophan, histidine, glycine, and arginine, but enriched in cysteine, methionine, alanine, and lysine. Carbohydrate determination showed that sciatin in composed of 11% sugar by weight with no detectable N-acetylneuraminic acid residues. Sedimentation velocity centrifugation studies revealed an S20,w0 of 5.11 with a frictional coefficient of 1.31. Sciatin had no detectable protease or acetylcholinesterase activity. The results of the present study provide new biochemical information on a macromolecule with biological activities similar to those expressed by the "maintenance" group of growth factors which includes such proteins as nerve growth factor.

Acetylcholinesterase↗
PubMed1980

Dependence of in vitro myogenesis on a trophic protein present in chicken embryo extract.

A trophic protein (sciatin) purified from sciatic nerves has been shown to enhance the morphological development and to promote the maintenance of skeletal muscle cells in vitro [Markelonis, G. J. & Oh, T. H. (1979) Proc. Natl. Acad. Sci. USA 76, 2470-2474]. We have elicited a specific antiserum against purified sciatin in rabbits. By using this antiserum, we have examined whether sciatin is also required for the initial differentiation of avian myogenic cells in vitro. Sciatin was found to be a component of chicken embryo extract, a constituent of culture medium required for myogenesis in vitro, by an immunodiffusion assay and by NaDodSO4 gel electrophoresis of immunoprecipitates. The removal of sciatin from chicken embryo extracts by immunoprecipitation with antiserum against sciatin completely inhibited myogenesis. When myogenic cells were grown in culture medium from which sciatin had been removed, the cells failed to differentiate beyond the myoblast stage. However, when sciatin (25 microgram/ml) was added to the sciatin-absorbed culture medium, normal myogenesis ensued. Furthermore, myogenic cells underwent normal myogenesis in the absence of embryo extract if sciatin (25 microgram/ml) was added to the culture medium. These results demonstrate that sciatin is the component of chicken embryo extract required for myogenesis and that the protein influences the initial differentiation of myogenic cells in vitro.

Animals↗
PubMed1978

Neurotrophic protein regulates muscle acetylcholinesterase in culture.

Skeletal muscles lose acetylcholinesterase in culture as a result of denervation. A protein fraction isolated from peripheral nerves maintained the level of acetylcholinesterase in cultures of aneural embryonic muscle or denervated adult chicken muscle. These results indicate that trophic regulation of muscle acetylcholinesterase might be mediated by a protein produced by nerves.

Acetylcholinesterase↗
PubMed1975

Increased activity of choline acetyltransferase and acetylcholinesterase in developing cultures of chick spinal cord: a correlation with morphological development.

Explants of 10-12-day-old embryonic chick spinal cord were cultured for up to 20 days by the "coverslip-roller" method. Morphological development of neurons as shown by the presence of mature neurons, myelinated axons and synaptic structures, was demonstrated by light and electron microscopy. Two important enzymes associated with acetylcholine transmitter metabolism, choline acetyltransferase (ChAc) and acetylcholinesterase (AChE), were assayed in cultures at selected time intervals. The activity of ChAc and AChE exhibited an increase of 60 per cent and 80 per cent, respectively, over a 20-day period. It is concluded that organotypic cultures of embryonic chick spinal cord show differentiation not only in morphological aspects, but also in biochemical terms through progressive development of ChAc and AChE.

Acetylcholinesterase↗
PubMed1972

Neurotrophic effect on isolated chick embryo muscle in culture.

Acetylcholinesterase activity in cultures of dissociated skeletal muscle prepared from the thigh muscle of the 10-day-old chick embryo was increased by the presence of innervating spinal cord explants, spinal cord explants in a parabiotic environment, and by media containing brain-spinal cord extract.

Acetylcholinesterase↗
PubMedDate not supplied

Neuroglial responses to the dopaminergic neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mouse striatum.

We have studied the reactive responses of both astrocytes and microglia to dopaminergic denervation of the striatum by MPTP. Following MPTP treatment, increased GFAP immunoreactivity reached a peak at 2 days and persisted for at least 6 weeks. Immunoreactivity to vimentin was also markedly increased in astrocytes 48 h after MPTP treatment. Striatal laminin immunoreactivity, however, appeared to be unaffected by drug treatment. GFAP protein levels increased to 196% and 321% of control 24 and 48 hours after MPTP treatment, respectively. Concomitantly, GFAP mRNA levels increased to 560% and 1620% of control, respectively. These reactive changes in striatal astrocytes in response to MPTP treatment were also accompanied by a reactive microglial response as evidenced by increased immunohistochemical visualization of striatal microglia using antibodies to Mac-1. Our results and those reported previously by O'Callaghan et al., strongly suggest that MPTP-induced reactive gliosis in mouse striatum is associated with reactive microglia, albeit without increased interleukin-1 beta.

Animals↗