PubMed Health⌕ Search

Biomedical subjects

B G Uzman

Publications and source records attributed to B G Uzman.

At least 19 recordsLinked to original sources
PubMed1990

Expression of GlN1-immunoreactive glycoproteins during development and regeneration in avian peripheral nerve.

Reactivity of the monoclonal antibody GlN1 was examined by immunocytochemistry and immunoblotting in quail and chick developing and regenerating wing nerves; its distribution is compared to that of HNK-1 which detects a carbohydrate epitope widely distributed in the nervous system. Reactivity was detected by immunofluorescence in cryostat sections, by a postembedding electron-microscopic immunogold technique and in immunoblots of nerve homogenates. From E11-E16, reactivity was detected in several large (120-260 kD) glycoprotein bands; and thereafter, principally, in 3 myelin-related glycoproteins (100, 26.5, and 21.5/ 19.5 kD). The HNK-1 carbohydrate epitope was detected in all these and in other bands permitting identification of the 100-kD moiety as the myelin-associated glycoprotein and the 26.5-kD protein as the P0 protein; the myelin-related 21.5/19.5-kD doublet appears as distinct, probable adhesion molecule(s). During development and regeneration, GlN1 reactivity detected by immunogold labeling of sections appeared first over the extracellular matrix, and later over thicker myelin sheaths. After transection, immunoreactivity in immunoblots was lost in distal stumps but reappeared with time; first in the larger (greater than 120 kD) moieties and then in the myelin-related bands, the same sequence observed in development. Electron-microscopic detection of both GlN1 and HNK-1 carbohydrate epitopes by immunogold labeling of resin-embedded sections is localized most consistently in the thicker (greater than 0.3 microns) myelin sheaths of nerves from chicks at or after hatching. Immunoblots of mature fowl nerve tissues homogenized at various stages of preparation for electron microscopy (after fixation or after fixation and dehydration) show sustained immunoreactivity in the 21.5/19.5-kD bands, reduction or complete suppression in others, and evidence of immunoreactivity in high molecular weight, presumably cross-linked, constituents that remain in the stacking gel portion of the blots.

Animals↗
PubMed1989

Peripheral nerve regeneration in quail-chick spinal cord chimeras treated with oral ciclosporin.

Regeneration of chimeric wing nerves in 2 quail-chick spinal cord chimeras is reported. The large DNA-containing quail nucleolar marker could not be distinguished in flattened cells, and in particular, in perineurial cell nuclei of chimeric nerves. With oral ciclosporin treatment, rejection of graft-derived nervous system tissues was acute and florid in one chimera, but followed a chronic, remitting course in the other.

Administration, Oral↗
PubMed1985

Rat neural tissue cathepsin D: ultrastructural immunocytochemistry.

The cellular and subcellular localization of cathepsin D, an aspartyl endopeptidase, was investigated in the central and peripheral nervous systems of the rat by light and electron microscopic immunocytochemistry. The reaction of rabbit anti-rat brain cathepsin D within ventral cervical spinal cord, cerebellum, corpus callosum, caudate nucleus, optic nerve, trigeminal ganglion, fifth cranial nerve and sciatic nerve was localized with an indirect immunoperoxidase technique. A number of tissue processing methods were utilized, but only in tissues fixed in paraformaldehyde-lysine-periodate and sectioned at thicknesses of 25-50 micron could antibody penetration, enzyme protein immunoreactivity and intact morphology be reliably attained. Immunoreactive cathepsin D was present in lysosomes and pleomorphic dense bodies of neurons in the anterior horn of spinal cord, cerebellar Purkinje and granule cell layers, caudate nucleus and trigeminal ganglion. Lysosomal localization of cathepsin D was also documented in oligodendrocytes, astrocytes, endothelial cells and Schwann cells. Reaction product was not observed in microglia although its presence there would be expected. With these methods, reaction product was not detected in the Golgi saccules of any cell type.

Aging↗
PubMed1984

Uses and contributions of diagnostic electron microscopy in surgical pathology: a study of 20 Veterans Administration hospitals.

Although the capability of electron microscopy to contribute to histopathologic diagnosis in selected instances, e.g., renal biopsies and biopsies of certain tumors, is generally recognized, its contribution in a broader range of surgical pathology accessions is not well established. To gain further information concerning this aspect of the use of electron microscopy, 7,193 surgical pathology reports, 290 (4 per cent) of which included electron microscopic findings, were analyzed; these reports represented all such accessions during the same single month at 20 VA medical centers. It was found that malignancies constituted 62 per cent of the lesions examined by electron microscopy but only 20 per cent of the total number of surgical cases examined by light microscopy. It was also found that the distribution of specimens by tissue site of origin differed considerably for specimens examined by electron microscopy and light microscopy; positive contributions of electron microscopy to diagnosis were found in 146 of the 290 electron microscopy cases (50 per cent), with higher percentages found in malignancies and in certain tissue site subsets (lower respiratory tract, soft tissue, kidney, skin, and lymph nodes with metastases); failure to examine some specimens (lung metastases to lymph nodes or other tissues and endobronchial biopsy specimens) suggests slight, but common, underutilization of electron microscopy in diagnosis.

Adult↗
PubMed1983

Mouse sciatic nerve regeneration through semipermeable tubes: a quantitative model.

The regeneration of transected mouse sciatic nerves using semipermeable acrylic copolymer tubes to enclose both stumps has been qualitatively assessed from 1 to 30 weeks post-operative. Quantitative morphometric analysis of electron micrograph montages of complete transverse sections of the segment regenerated between stumps has permitted determinations of the percents of total area occupied by the various tissue constituents--blood vessels, epineurium, perineurium, endoneurium, myelinated axon/Schwann cell units, and unmyelinated axon/Schwann cell units. Significant differences were found in the total cross-sectional area of segments regenerated through tubes of 1.0 mm versus 0.5 mm internal diameters. Segments regenerated with the distal stump inserted in the tube contained significantly greater percentages of neural units and were significantly larger at 8 weeks post-operative compared to segments regenerated for 9-10 weeks with the distal stump avulsed. The morphometric method permits rapid quantitation of sizeable electron micrograph montages which at 1300 X permit all types of tissue components, including the unmyelinated axons, to be visualized.

Acrylic Resins↗
PubMed1982

The renal degradation of myelin basic protein peptide 43-88 by two enzymes in different subcellular fractions.

Previous studies have demonstrated that the kidney is the major site for clearance and catabolism of a peptide (residues 43-88) of encephalitogenic or basic protein (BP) derived from central-nervous-system myelin. In the present investigation rat renal tissue was shown to be capable of degrading human BP peptide 43-88 over the pH range 4-11.5 with peaks of activity at pH5 and pH9. The enzymic activity at pH5 was localized mainly to the 5900 g pellet (crude mitochondrial fraction) and, on the basis of its sulphydryl features, was inferred to be cathepsin B. The enzyme activity at pH9 was greatly enriched in the 100 000 g pellet (microsomal brush-border fraction), and its sensitivity to inhibitors suggested that it was a metalloproteinase. The activity at alkaline pH in the 100 000 g pellet was stimulated 3-fold by non-ionic detergents and 20-fold by ATP and polyphosphates. Through a series of experiments the ATP stimulation of the alkaline proteinase activity was concluded to be the result of a reversal of inhibition imposed by the presence of another cationic protein, methylated bovine serum albumin. Inhibition by certain bivalent cations, the irregular effects of chelators and the effects of poly-L-lysine supported this conclusion. These studies indicate the availability of renal enzymes of different types and in different cellular compartments that are capable of degrading BP peptide 43-88. In particular, the relative amounts of bivalent cations, anions and charged proteins and peptides are likely to be major influences on the activity of the alkaline proteinase in vivo. The control of this degradation as well as the features of the smaller fragments of the peptide formed may determine biological and immune events subsequent to the release of this potentially autoantigenic material.

Adenosine Triphosphate↗
PubMed1981

Increased myelination related enzymatic activities in neuron-glial heterokarya.

Two enzymatic activities associated with myelination were determined in a neuron-glial heterokaryon system. Significant increases of 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNP) and UDP-galactose-ceramide galactosyl transferase (CGalt) activities were noted in heterokarya produced in vitro between 17-day-old rat cerebral neurons and differentiated cultured rat glioma (C6) cells; rat cerebral neurons and calf brain white matter glial cells or differentiated neuroblastoma 2a cells and differentiated C6 cells. Morphological expression of differentiation, such as neurite extension, was also noted in the heterokarya. Findings suggest that the glial expression of myelination related enzymatic activities could be under a neuronal regulatory control and further suggest that the interaction of neurons and glia is necessary for myelinogenesis and maintenance of the myelin sheath components.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1972

Fine structural localization of cholesterol-1,2- 3 H in degenerating and regenerating mouse sciatic nerve.

The localization of (3)H-labeled cholesterol in nerves undergoing degeneration and regeneration was studied by radioautography at the electron microscope level. Two types of experiments were carried out: (a) Cholesterol-1,2-(3)H was injected intraperitoneally into suckling mice. 5 wk later, Wallerian degeneration was induced in the middle branch of the sciatic nerve, carefully preserving the collateral branches. The animals were then sacrificed at various times after the operation. During degeneration, radioactivity was found over myelin debris and fat droplets. In early stages of regeneration, radioactivity was found in myelin debris and regenerating myelin sheaths. Afterwards, radioactivity was found predominantly over the regenerated myelin sheaths. Radioactivity was also associated with the myelin sheaths of the unaltered fibers, (b) Wallerian degeneration was induced in the middle branch of the sciatic nerves of an adult mouse, preserving the collateral branches. Cholesterol-1,2-(3)H was injected 24 and 48 hr after the operation and the animal was sacrificed 6 wk later. Radioactivity was found in the myelin sheaths of the regenerated and unaltered fibers. The results from these experiments indicate that: (a) exogenous cholesterol incorporated into peripheral nerve during myelination remains within the nerve when it undergoes degeneration. Such cholesterol is kept in the myelin debris as an exchangeable pool from which it is reutilized for the formation of the newly regenerating fibers, especially myelin. (b) exogenous cholesterol incorporated into the nerves at the time that degeneration is beginning is also used in the formation of new myelin sheaths during regeneration, (c) mature myelin maintains its ability to incorporate cholesterol.

Animals↗