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Biomedical subjects

L F Eng

Publications and source records attributed to L F Eng.

At least 109 records · Page 6Linked to original sources
PubMed1982

Analysis and comparison of in vitro synthesized glial fibrillary acidic protein with rat CNS intermediate filament proteins.

Intermediate filament (IF) proteins from rat spinal cord were analyzed by two-dimensional gel electrophoresis and compared with the in vitro translation products of a messenger RNA-dependent reticulocyte lysate system stimulated with 16-day-old rat brain polysomes. In two dimensions, the molecular weight 49,000 to 50,000 band of the IF preparation resolved to seven spots, whereas antiserum to glial fibrillary acidic (GFA) protein precipitated only two immediately adjacent radiolabeled in vitro synthesized products, with molecular weights of 49,000 to 50,000. Autoradiographs of two-dimensional gels of extracted IF proteins incubated with iodinated IgG fraction of GFA protein antiserum showed that all seven spots were recognized by the antiserum. These observations suggest that the primary gene product of GFA protein is modified either by post-translational processing or experimental artifact.

Animals↗
PubMed1982

Processing techniques for the demonstration of myelin basic protein in paraffin-embedded optic nerve: an immunoperoxidase study of the developing albino rat.

A comparison was made of the effects of various fixation and processing conditions upon the antigenicity of myelin basic protein (MBP) in sections of paraffin-embedded optic nerve from the developing albino rat as judged by the unlabeled peroxidase-antiperoxidase technique. The fixatives used were: Perfix, 4% and 2% buffered paraformaldehyde (pH 7.4), 10% buffered formalin (pH 7.4); Bouin's, Clark's, and Carnoy's fixatives, and 20% formalin in a solution of HgCl2 that had been saturated at 1 degrees C. Perfix appeared to be the best fixative for the preservation of morphology and MBP antigenicity during the early stages of myelinogenesis but was not satisfactory during the later stages. The buffered aldehydes were slightly more destructive of MBP antigenicity than was Perfix, but they produced satisfactory results following the first postnatal week. Bouin's fixative was similar in effect to the buffered aldehydes, but nonspecific background staining was higher. HgCl2/formalin, Clark's and Carnoy's fixatives were unsuitable. No differences were noted in staining between material processed for embedding using 5, 30, or 60 min schedules.

Acetates↗
PubMed1981

Glial fibrillary acidic protein in the optic nerve of the developing albino rat: an immunoperoxidase study of paraffin-embedded tissue.

The unlabeled peroxidase-anti-peroxidase method was used to stain glial fibrillary acidic (GFA) protein in the optic nerve of the developing albino rat. Optic nerves from animals ranging in age from the day of birth to adulthood were embedded in paraffin following fixation with various agents for times ranging from 30 minutes to 48 hours. GFA protein activity was demonstrable at birth in large astrocytic processes following fixation with alcohols or with Perfix for short intervals, but not with 4% or 2% buffered paraformaldehyde solutions. With increasing age, GFA protein could be demonstrated using higher aldehyde concentrations, longer fixation times, and longer paraffin embedding schedules. At all ages GFA protein activity was greater following treatment with nonaldehyde fixatives rather than those containing formaldehyde or glutaraldehyde. At birth the majority of GFA protein-containing processes were confined to planes which were perpendicular to the axons of the optic nerve. With increasing age, tangential and longitudinal processes became more numerous until, in the mature optic nerve, astrocytic processes were best characterized as being multidirectional.

Aging↗
PubMed1981

Glial fibrillary acidic protein in cryogenic lesions of the rat brain.

Histologic sections of rat brains obtained at time intervals ranging from 30 min to 48 h following a cryogenic lesion placed on the surface of the parietal lobe, were immunocytochemically stained for glial fibrillary acidic (GFA) protein (glial filaments), IgG and albumin. Intense staining for the GFA protein and enlargement of astrocytes in the subcortical white matter and corpus callosum, were demonstrated near the lesion at 30 min and spread throughout the white matter up to 48 h. The early reaction of the astrocytes suggests that disassembly of glial filaments or new GFA synthesis may contribute to astrocytic changes.

Animals↗
PubMed1981

Post-embedding immunoperoxidase staining of glial fibrillary acidic protein for light and electron microscopy.

Post-embedding peroxidase-antiperoxidase methods to stain glial fibrillary acidic (GFA) protein in Araldite-embedded sections for light and electron microscopy were developed. The Jimpy mouse spinal cord was used because it is gliotic and contains abundant glial filaments and GFA protein. For light microscopy, specific staining was obtained in thick and in ultrathin sections mounted on glass following removal of the plastic with sodium ethoxide. Consistent specific staining for GFA protein in ultrathin sections mounted on nickel grids required partial removal of the plastic with 1% sodium ethoxide and further treatment with 2% sodium dodecyl sulfate (SDS).

Animals↗
PubMed1981

Heterogeneity of Genotypic and phenotypic characteristics of fifteen permanent cell lines derived from human gliomas.

Six new permanent cell lines were established from human gliomas and compared to nine other cell lines from human gliomas. All fifteen lines had individually distinct HLA phenotypes and all but two, which were from a black patient, had type B glucose-6-phosphate-de;hydrogenase isoenzymes. Morphologically, the lines could be classified into four patterns descriptively designated as fibroblastic, fascicular, epithelial, or glial. Four of the lines grew progressively and could be serially transplanted when injected into athymic mice; two others grew initially and then regressed. From none to 100% of cells developed elongated tapering processes and showed reduction in nuclear-cytoplasmic ratio in the presence of 1 mM cyclic AMP and theophylline. Levels of 2'-3' cyclic nucleotide 3'-phosphohydrolase activity ranged from nondetectable to 12.78 +/- 1.49 micromoles 2' AMP formed per hr mgm total protein. None of the lines had detectable S-100 protein, but two had readily demonstrable glial fibrillary acidic protein in indirect immunofluorescence. Fibronectin levels in spent culture supernatants ranged from undetectable levels to 21.4 micrograms/ml/10(5) cells. All but one line shared surface antigens with normal human adult or fetal brain, as detected in absorption analyses with nonhuman primate antiserum raised against glioblastoma multiforme tissue or cell line U-251 MG. Although there were many common properties of the lines, each line had a unique profile of the parameters evaluated. This heterogeneity most likely reflects the individuality of the tumors of origin and individual genotypes and capacity for a range of phenotypic expression of cells.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1981

Glial fibrillary acidic protein in hepatic encephalopathy. An immunohistochemical study.

Basal ganglia, thalamus, cerebral cortex, and subcortical white matter were studied in ten cases of hepatic encephalopathy (HE), including three cases of acquired hepatocerebral degeneration (HCD), and in thirteen age-matched controls using the peroxidase-antiperoxidase immunohistochemical staining technique for glial fibrillary acidic (GFA) protein. HE cases all had pronounced Alzheimer type II astrocytosis. The perikarya and processes of Alzheimer type II glia did not stain for GFA protein. Staining of perivascular endfeet was evaluated by first selecting blood vessels throughout the gray and white matter in hematoxylin and eosin-stained slides to eliminate bias. The vessels were then identified in sections stained for GFA protein and graded as to complete circumferential, partial circumferential, or absence of staining. Both the degree and frequency of staining in the basal ganglia, thalamus, and cerebral cortex were significantly decreased in cases of HE; no statistically significant differences were found for the white matter. There were no significant differences in staining between HCD and other HE cases. These findings show that the Alzheimer II change is associated with a loss of immunohistochemically detectable GFA protein in cerebral gray matter.

Aged↗
PubMed1981

Anaplastic human gliomas grown in athymic mice. Morphology and glial fibrillary acidic protein expression.

The morphologic and biochemical characteristics of human surgical biopsy specimens taken from 17 patients with anaplastic human gliomas and of athymic mouse-grown tumors derived from them were examined. Fourteen were categorized as glioblastoma multiforme, one as an anaplastic astrocytoma, one as a recurrent glioblastoma multiforme, and one as a gliosarcoma. Fifteen of 17 tumors stained positively immunohistochemically for glial fibrillary acidic protein (GFAP), a glial-specific marker. When portions of the 17 surgical biopsy specimens were injected into the flank subcutaneous space of athymic mice, 16 produced tumors; different portions of a single biopsy specimen were used to establish three separate tumor lines; in toto, 18 tumor lines were established. Mouse-borne tumors contained various proportions of fibrillary and protoplasmic astrocytes, gemistocytes, small anaplastic cells, and multinucleated giant cells. Some were more homogeneous than the human tumors from which they were derived, while others contained a mixed population similar to that of the original biopsy specimen. Of these initial 18 tumors, 16 were stained for GFAP and 14 contained from fewer than 5% to almost 100% GFAP-expressing cells. Ten of the tumor lines were studied in serial passage, several demonstrating increased cellularity with increased passage. GFAP expression was followed through serial passage, and 7 of 10 tumor lines continued to express it, often in reduced amounts, and 2 of 10 ceased expression, one (the gliosarcoma) never having expressed it. These data demonstrate that while athymic mouse-borne human anaplastic gliomas retained some features of the human tumors from which they were derived, they varied from one another morphologically. These mouse-borne tumors also continued to evolve, often changing their levels of GFAP and demonstrating increased cellularity with passage.

Animals↗
PubMed1980

Glial fibrillary acidic protein in the retina of the developing albino rat: an immunoperoxidase study of paraffin-embedded tissue.

The peroxidase-anti-peroxidase method was used on paraffin-embedded material to demonstrate the distribution of glial fibrillary acidic (GFA) protein, an astrocyte-specific protein, in the developing retina of the albino rat. At birth activity was scant and was confined to scattered, poorly differentiated cells in the inner retinal layers near the optic disc. At 3 days primitive astrocytes which displayed GFA protein activity were confined to the stratum opticum near the optic disc. With increasing age these cells were found at greater distances from the optic disc and began to assume the appearance of typical fibrous astrocytes. By 30 days the perikarya of these cells were confined almost exclusively to the region between the nerve fiber layer and the inner limiting membrane. The processes of these cells terminated either in suckerlike end-feet upon blood vessels or, to a lesser extent, ended in relation to axon fascicles of the nerve fiber layer. A second population of GFA protein-active cells existed as perivascular glia which were found upon vessels in the inner portion of the stratum opticum in young animals. In the mature retina perivascular glia were found on vessels throughout the stratum opticum and in the inner portion of the inner plexiform layer. Unequivocal staining of Müller cells or their processes was not obtained. The best staining was obtained with fixatives containing minimal concentrations of aldehydes, especially in tissue from younger animals. The fixative which gave the best preservation of cellular structure along with preservation of GFA protein antigenicity was Perfix (Fischer Scientific Company).

Animals↗
PubMed1980

Immunoperoxidase staining of glial fibrillary acidic (GFA) protein polymerized in vitro: an ultramicroscopic study.

The unlabeled antibody peroxidase-antiperoxidase (PAP) method of Sternberger et al. has been employed at the ultramicroscopic level to stain filaments polymerized in vitro from aqueous extracts of multiple sclerosis (MS) plaques. The filaments were heavily decorated with antiserum to the glial fibrillary acidic (GFA) protein but not stained with serum absorbed with GFA protein, preimmunization serum, or anti-rat brain tubulin but was not stained with antiserum to the GFA protein. The present study provides direct morphological evidence that filaments polymerized in vitro from extracts of MS plaques contain the GFA protein.

Animals↗
PubMed1980

Cell-free synthesis of glial fibrillary acidic protein.

Glial fibrillary acidic (GFA) protein has been synthesized in an RNA-dependent cell-free system derived from rabbit reticulocytes. The cell-free synthesized product appears to have the same size as GFA protein isolated from bovine spinal cord, thus showing that GFA protein does not undergo detectable proteolytic processing.

Animals↗
PubMed1980

A neurochemical and immunocytochemical study of P2 protein in human and bovine nervous systems.

The anatomical distribution of P2 protein was studied in human autopsy tissue. Spinal cord (SC) and peripheral nerve (PN) were stained by the peroxidase-antiperoxidase method with antisera to bovine P2, glial fibrillary acidic protein, and myelin basic protein (BP). P2 antiserum did not stain all of the myelin in the PN. The staining was randomly distributed and discontinuous along a given myelinated axon. P2 antiserum also stained SC myelin in a pattern similar to the PN. Only a fraction of the sheaths stained, in contrast to BP antiserum that stained all myelin sheaths in both the SC and PN. P2-positive myelin was distributed throughout the SC white matter, including an occasional myelinated fiber in the SC grey matter. P2 and BP antisera did not stain regions of demyelination in a case of idiopathic polyneuritis, while adjacent myelinated PN stained normally. Absorption of the P2 antiserum with P2, bovine PN or bovine SC (carefully dissected to eliminate PN contamination) nullified the specific staining in both the PN and SC; however, absorption with BP or hemispheric myelin did not eliminate P2 staining. The P2 antiserum formed a single immunodiffusion line with pure P2 and acid extracts of bovine SC and PN myelin, but not with an acid extract of bovine hemispheric myelin. Electrophoresis of defatted bovine SC produced a distinct band corresponding to P2. Therefore, three lines of evidence, immunocytochemical, immunodiffusion and electrophoretic, suggest that P2 is present in PN and SC but not in hemispheric myelin.

Animals↗
PubMed1980

Immunocytologic analyses of 10 nm intermediate filaments in the nervous system of Myxicola.

Antibodies prepared in rabbits against Myxicola infundibulum neurofilaments have been employed to stain neurofilaments immunohistochemically in intact Myxicola infundibulum nervous tissue. Paraffin-embedded and frozen sections (5--6 mu) were examined at the light microscopic level with Sternberger's peroxidase-antiperoxidase method, and Vibratome (20--40 mu) sections were studied at the ultrastructural level with Nakane's conjugated peroxidase method. The neurofilament antibody stained only neurons and axons at the light microscopic level. The staining pattern at the electron microscopic level corresponded to the neurofilaments within axons and neurons. Glial cells, which surround the axons, contain large bundles of filaments that resemble astrocytic filaments in mammalian astrocytes. These filaments do not stain with the anti-neurofilament antibody. Neurons, neurofilaments, glial cells, glial filaments, and nonnervous tissue showed no peroxidase staining when specific antiserum absorbed with neurofilaments was used. These structures were also unstained when antiserum to the glial fibrillary acidic protein of mammalian central nervous system astrocytes was substituted for the neurofilament antiserum. Therefore, in Myxicola infundibulum, the antigenic determinants of the neurofilament protein, as recognized immunohistochemically by anti-neurofilament protein antibodies, are not shared with those of glial filaments.

Animals↗
PubMed1979

Studies of human and bovine spinal nerve roots and the outgrowth of CNS tissues into the nerve root entry zone.

The outpouching of CNS tissues into the entering spinal nerve roots was documented by light and electron microscopy of human and bovine tissues. Astrocytic processes containing large bundles of glial filaments were very prominent in the nerve entry zone and extended for short distances into the adjacent endoneurium of the spinal nerve roots. Antiserum raised to glial acidic fibrillary (GFA) protein stained these glial elements, thereby characterizing the dome-shaped evaginations of CNS tissues into the nerve root entry zones. Antisera to CNS basic protein showed enhanced staining in the nerve entry zone. Analyses of nerve proteins by SDS gel electrophoresis disclosed a prominent 49,000 MW protein in the bovine and human nerve root entry zone. This protein was also prominent in spinal cord white matter, but was not seen in nerve roots which were not admixed with glial tissues. This finding supported the view that a 49,000 MW protein is a glial filaments but is not a component of bovine or human neurofilaments.

Animals↗