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Biomedical subjects

C Mezei

Publications and source records attributed to C Mezei.

At least 37 records · Page 2Linked to original sources
PubMed1985

In vitro translation of mRNA from the developing sciatic nerve.

Poly(A+)RNA from sciatic nerves of embryos and chicks was translated in a rabbit reticulocyte cell-free system. The 30-K mol. wt. PO protein which is the major and specific protein constituent of peripheral nervous system myelin was used as a marker of myelin synthesis in the preparations. Immunoprecipitation of total translation products with rabbit anti-PO protein antibody showed the presence of a 29K protein band on the autoradiograms. The intensity of this specific immunoprecipitated band increased significantly from very low levels with RNA from the 15-day embryonic nerve to a maximum with extracts from 1-day-old chicks. This increase parallels that of the rapid deposition of the PO protein in the developing sciatic nerve in vivo. The experiments demonstrate for the first time, that it is possible to show synthesis of PO protein in vitro using exogenous RNA as the template.

Animals↗
PubMed1984

PO protein and 2',3'-cyclic-nucleotide 3'-phosphodiesterase activity in the peripheral nerve and subcellular fractions of the Trembler mouse.

To investigate the biochemical abnormalities of the Trembler mouse, the level of the PO protein (as % of total protein) and the activity of CNP was compared in the sciatic nerve and subcellular fractions of normal and mutant littermates. There was a significant decrease in both of these myelin markers in total nerve homgenates of the neurological mutant compared with the control animals. Immunoassay of the PO protein and polyacrylamide gel analysis of proteins indicated an accumulation of a protein with an apparent molecular weight of 67K in mutant nerve extracts. The mutant nerve also had relatively decreased levels of a protein of molecular weight about 41K that cross-reacted with antibody to PO protein. The Trembler mouse exhibited a larger percentage recovery of PO protein and CNP activity in subcellular fractions denser than the myelin sheath. Together these results are consistent with the theories that these denser components represent immature forms of myelin and that the Trembler mutant is characterized by hypomyelination.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1984

Solid-phase immunoassay of PO glycoprotein of peripheral nerve myelin.

To explore the immunological properties of PO protein, antibodies were elicited in rabbits against the purified chick PO protein. Peripheral nervous system protein was fractionated on sodium dodecyl sulfate-polyacrylamide slab gels and then transferred electrophoretically ("blotted") onto nitrocellulose sheets. The PO protein was detected by its capacity to bind its specific antibody present in the rabbit serum. The PO-specific antibody complex was then exposed to goat anti-rabbit immunoglobulin G (IgG) coupled to peroxidase or labeled with 125I. The resulting PO antigen-antibody "sandwich" was visualized and quantitated by densitometry of the colored peroxidase reaction product or by autoradiography and gamma-radiation counting of the 125I-IgG complex. The methods permitted quantitation of the PO protein in various nerve extracts. The limit of detection of the PO antigen was about 1 ng of protein. The antibody was specific for the PO glycoprotein in the peripheral nerve extracts. The PO proteins from various species, including human, were also detected by the antibody to chick PO protein. Preliminary experiments indicate the solid-phase immunoassay is a useful method for monitoring PO protein levels in small quantities of tissue extracts under various physiological and pathological conditions.

Animals↗
PubMed1981

Effect of Wallerian degeneration on histamine concentration of the peripheral nerve.

One sciatic nerve of a White Leghorn hen was severed and the distal portion was allowed to undergo Wallerian degeneration. The change in histamine and DNA concentration and mast cell number was measured at different times following nerve sectioning in the proximal regenerating, distal degenerating, and intact, contralateral nerves. The experimental results revealed a significant accumulation of histamine in the proximal desheathed segment and in the contralateral "functional nerve," whereas the biogenic amine in the distal desheathed nerve significantly decreased. The pattern of change of histamine in the distal and proximal nerve sheaths was different: it dropped at 2 h and then rose in the later stages of Wallerian degeneration. In the distal desheathed nerves and in both the proximal and distal nerve sheaths DNA increased significantly by 14 days. The number of mast cells appeared to be highest in the 14-day distal nerve and in the 7-day proximal nerve sheaths. These results support a dual localization of histamine in the peripheral nerve, and are consistent with the interpretation that the amine has either some role in neurotransmission or in the process of growth and regeneration.

Animals↗
PubMed1981

The PO protein of chick sciatic nerve myelin: purification and partial characterization.

The PO protein of the myelin of chick sciatic nerve was isolated and purified by propanoic acid extraction of peripheral nervous system (PNS) myelin, delipidation, Sepharose CL-6B chromatography in the presence of sodium dodecyl sulfate (SDS), and preparative SDS-polyacrylamide gel electrophoresis (PAGE). Approximately 15% of the PO protein in the sciatic nerve myelin was recovered in a homogeneous state. The purified protein monomer has an apparent molecular weight of 32.1K as determined by gel electrophoresis. The PO protein undergoes extensive aggregation during exhaustive dialysis and freeze-drying and yields stable dimers, trimers, and tetramers. The aggregation of the PO protein after freeze-drying is independent of the presence of a reducing agent (2-mercaptoethanol) in the solubilizing medium. The PO protein is a glycoprotein. The amino acid composition of the chick PO protein indicates a definite species difference when compared with mammalian PO proteins although the NH2-terminal isoleucine residue seems to have been retained during evolution.

Amino Acids↗
PubMed1979

Studies on 2', 3'-cyclic AMP 3'-phosphohydrolase in rabbit skin.

Previous studies indicated that 2', 3'-cyclic AMP 3'-phosphohydrolase, an enzyme which splits the 3'-phosphate bond of the 2', 3'-cyclic AMP, is primarily confined to nervous tissue. The physiological function of this enzyme is still unknown. In the present study this enzyme was found to be active in various organs of rabbit, i.e. liver, kidney, heart and skin, although to a much lesser extent than in brain and sciatic nerve. The finding of this enzyme in the skin generated further studies to measure the enzyme activity in normal and diseased skin. Chemically induced (surfactant-treated) skin disorder was used as a model for the present study. Topical application of Polysorbate 85 resulted in a two fold increase of the enzyme activity in rabbit skin. The results suggest that this enzyme may have some role in the repair mechanisms, particularly in the regeneration of damaged membranes.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1978

Ontogenesis of histamine in the chick nervous system.

Tissues from the central and peripheral nervous systems of the chick were analyzed for concentration of histamine (Hm) during development. Of the three CNS organs examined, cerebral hemispheres had the highest Hm content. Expressed on the bases of wet weight, protein, and DNA concentrations, sciatic nerve and the pineal gland had the highest levels of this biogenic amine of the five tissues investigated. The concentration of Hm was higher in the cerebellum, cerebral hemispheres, and thalamus of adult animals than in the 15 to 17-day-old embryos. The level of Hm rose markedly in the sciatic nerve and pineal gland after the 15th day of embryonic development. These data might indicate a possible involvement of Hm in controlling the course of maturation of certain organs in the nervous system.

Age Factors↗
PubMed1976

Characterization of myelin of chick sciatic nerve during development.

Myelin was isolated from the sciatic nerves of chicks of ages 18-day embryonic, 1-day, 4-day, 7-day post-hatch, and adult to study developmental changes in lipid composition of this structure. The yield of myelin increased throughout the early stages of development and the preparations were of high purity. Although the lipid content of the myelin did not change, significant changes took place in lipid composition during development. The most significant changes were a relative increase in cerebrosides, phosphatidalethanolamine and long-chain fatty acids of cerebrosides, and a relative decrease in the content of phosphatidylserine and phosphatidylethanolamine. A second fraction ("lower band") was obtained during the isolation procedure. This "lower band" was present at all developmental stages and layered consistently at the interface of 1.2 and 0.8 M sucrose on a discontinuous gradient. The quantity of this fraction did not change during development and it differed from myelin in electron microscopic appearance. Its lipid composition, which did not change, resembled that of 18-day embryonic myelin in its high phospholipid:cholesterol ratio and low galactolipid content. The enzyme, 2':3'-cyclic-nucleosidemonophosphate phosphodiesterase was found to be present in both the myelin and "lower band" fractions; however there was no enrichment of this enzyme in purified myelin.

Aging↗
PubMed1975

Histamine-n-methyltransferase activity of the nervous system of the chick during development.

The developmental course of histamine-N-methyltransferase activity was determined in the chick pineal gland, thalamus, cerebral hemispheres, cerebellum and sciatic nerve from the 13-day embryo to 1-week post-hatching. In each tissue, low levels of enzyme activities were detectable in the 13-day embryo. Thereafter, to the stage of hatching activity rose rapidly in the pineals, thalamus and peripheral nerve. Enzyme activity in the pineals decreased after hatching and remined at a relatively low pre-hatch level in the 7-day chick. In the sciatic nerve and thalamus activity also dropped slightly after hatching. The increase of enzyme activity in the cerebellum and cerebellum hemispheres was very gradual after the 13th day of embryonic stage and maximum activities were obtained only 2 days after hatching. Highest specific activities of the enzyme were detected in the sciatic nerve, pineals and thalamus at each developmental stage. The Km values for histamine and S-adenosyl-l-methionine and the behavior towards certain drugs of the enzyme in the pineals and sciatic nerve did not change significantly during development.

Age Factors↗