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Biomedical subjects

L F Eng

Publications and source records attributed to L F Eng.

At least 91 records · Page 5Linked to original sources
PubMed1985

Immunocytochemical studies of substance P and Met-enkephalin in the basal ganglia and substantia nigra in Huntington's, Parkinson's and Alzheimer's diseases.

Immunocytochemical studies of the distribution and intensity of Substance P and Met-enkephalin staining in the basal ganglia and substantia nigra were carried out in five cases each of brains from patients with Huntington's disease, Parkinson's disease, Alzheimer's disease, and normal controls. The usefulness of the peroxidase-antiperoxidase method for human autopsy material was confirmed. Substance P and Met-enkephalin fibers were distributed in essentially the same pattern as described in experimental animals and in human brains. In Huntington's disease brains decreased Substance P staining was found in the internal globus pallidus and the substantia nigra, in agreement with radioimmunoassay studies by others. Met-enkephalin staining in the external globus pallidus was of normal intensity, although present within a shrunken area. In Parkinson's and Alzheimer's diseases there was intense immunoreactivity for Substance P in the globus pallidus and substantia nigra, and for Met-enkephalin in the globus pallidus, at variance with reported decreases in Parkinson's disease by radioimmunoassay, but in essential agreement with other immunocytochemical studies. Immunocytochemical methods complement radioimmunoassays of human brain and may help in mapping neuropeptidergic pathways and in pinpointing abnormalities in these pathways in basal ganglia disorders.

Aged↗
PubMed1985

Studies on a cerebellar 50,000-dalton protein associated with cerebellar hypoplasia in jaundiced Gunn rats: its identity with glial fibrillary acidic protein as evidenced by the improved immunoblotting method.

On the basis of our previous findings that a 50,000-dalton protein (GR-50) shows a marked increase in the hypoplastic cerebellum of jaundiced homozygous Gunn rats and its electrophoretic behavior is similar to that of glial fibrillary acidic protein (GFAP), we tried to identify GR-50 as GFAP by two-dimensional electrophoresis of rat cerebellar membrane proteins using an improved immunoblotting method. In this method a blot immunostained for a specific antigen was also visualized for other proteins, thereby enabling us to determine the location of the antigen on the blot more precisely. With the methodology it was found that GFAP antigen occupied exactly the same position as GR-50 on the blot, suggesting strongly the identity of both proteins. Immunohistochemical studies revealed that in the cerebellum of homozygotes compared with that of heterozygotes GFAP antigen was greatly increased and that it was especially rich in the homozygous rat cerebellar lobules with a high degree of hypoplasia. Further, it was shown that not only the fibers of the Bergmann glial cells but also their somata were intensely immunostained in the affected lobules. A 47,000-dalton protein (SG-47), which has been reported to be increased in staggerer mutant mice with cerebellar hypoplasia, also immunoreacted with the antiserum to GFAP.

Animals↗
PubMed1984

The structure of pseudomeissnerian corpuscles. An immunohistochemical study.

Immunohistochemical staining for S-100 protein was carried out on one case of von Recklinghausen's neurofibroma and one of giant congenital nevus. Uniformly positive staining was obtained in all cells of the numerous pseudomeissnerian corpuscles in both cases. These structures thus appear, like the true Wagner-Meissner tactile nerve endings, to consist entirely of Schwann cells and not to contain any demonstrable perineurial component.

Humans↗
PubMed1984

Myelin basic protein in the optic nerve of the developing albino rat: an immunoperoxidase study of paraffin embedded tissue.

The distribution of myelin basic protein (MBP) was determined by application of the unlabeled peroxidase-anti-peroxidase method to sections of paraffin embedded optic nerve taken from the developing albino rat. MBP was not detected in optic nerves from animals younger than 90 hours postnatum. MBP staining presented first as faint, diffuse deposits of chromagen which were found in approximately one-third of the 90 hour subjects. The number of MBP positive regions and the intensity of staining of these regions increased rapidly with age. There was no obvious radial gradient in the distribution of MBP in cross sections of developing optic nerves, nor were smooth central/peripheral gradients apparent in longitudinal sections.

Age Factors↗
PubMed1984

Metabolic studies in vitro of the CNS cytoskeletal proteins: synthesis and degradation.

General aspects of metabolic features of the most prominent CNS intermediate filament proteins, the 200,000 (200K), 150,000 (150K), and 70,000 (70K) dalton proteins of the neuron, and the glial fibrillary acidic protein (GFAP) have been explored using the incubated spinal cord slice from the rat. Measurement of short-term uptake of 3H-labeled amino acids into the individual proteins separated on polyacrylamide gels revealed that of the three neurofilament proteins, 200K was most metabolically active, 150K was less active, and 70K contained very little incorporated radioactivity. Glial fibrillary acidic protein based on Coomassie blue stain affinity showed less metabolic activity than any of the neurofilament proteins. Those relationships were constant at all ages, but the metabolic activity of all CNS intermediate filaments decreased with age. When Ca2+ was present in the medium of the incubated slices, the intermediate filaments were rapidly destroyed, but GFAP was more resistant to degradation than the neurofilament proteins. GFAP and probably the neurofilament proteins also were relatively resistant to Ca2+-activated degradative mechanisms in spinal cords of rats at younger ages (15 day) than in those of older animals (10-18 months). It is likely that the Ca2+ activated protease is less active in developing animals in which the nerve tracts are still elongating, than in adults. These results suggest that GFAP is less active metabolically and more resistant to degradation than the neurofilament proteins at all stages of maturation, but that metabolic activity of all CNS intermediate filaments decreases with age while the susceptibility to degradation increases.

Animals↗
PubMed1984

Glial fibrillary acidic protein in regenerating teleost spinal cord.

Immunohistological and ultrastructural studies were carried out on normal and regenerating spinal cord of the gymnotid Sternarchus albifrons, and in the brain and spinal cord of the goldfish Carassius auratus, to examine the distribution of glial fibrillary acidic protein (GFAP) in these tissues. Sections of normal goldfish brain and spinal cord exhibited positive staining for GFAP. In normal Sternarchus spinal cord, electron microscopy has revealed filament-filled astrocytic processes; however, such astrocytic profiles were more numerous in regenerated cord. Likewise, while normal Sternarchus spinal cord showed only a small amount of GFAP staining, regenerated cords were strongly positive for GFAP. Positive staining with anti-GFAP was observed along the entire length of the regenerated cord in Sternarchus, and was especially strong in the transition zone between regenerated and unregenerated cord. Both regeneration of neurites and production of new neuronal cell bodies occur readily in such regenerating Sternarchus spinal cords (Anderson MJ, Waxman SG: J Hirnforsch 24: 371, 1983). These results demonstrate that the presence of GFAP and reactive astrocytes in Sternarchus spinal cord does not prevent neuronal regeneration in this species.

Animals↗
PubMed1983

Immunocytochemical staining for glial fibrillary acidic protein and the metabolism of cytoskeletal proteins in experimental allergic encephalomyelitis.

Spinal cord sections from Lewis rats with acute experimental allergic encephalomyelitis (EAE) showed greatly increased staining of astrocytes when stained immunocytochemically for glial fibrillary acidic protein (GFAP). Fibrous processes in white matter were heavily stained early in the course of the disease when paralysis was first evident (10-12 days after injection of guinea pig spinal cord myelin), then protoplasmic astrocytes were stained in the gray matter and became more heavily stained at 20 days post-injection. The stained astrocytes were evenly distributed throughout the tissue, and did not correspond to the sites of the lesions. Spinal cord slices of control and EAE rats were incubated with [3H]amino acids, then cytoskeletal proteins were prepared in an enriched fraction, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the protein bands counted for radioactivity. In the EAE rat all cytoskeletal proteins, including the neurofilaments, vimentin, microtubules, GFAP and actin, showed increased uptake of radioactive amino acids. Immunoprecipitation of GFAP with specific antiserum showed increased radioactivity in the complex beginning at day 10 when cellular infiltration was beginning in the EAE animals. As the disease became acute, the radioactivity in the immunoprecipitated GFAP increased, in some cases to very high levels, then by day 18 when recovery was underway, the radioactivity had fallen to normal levels. Possible agents causing metabolic activation of protein synthesis in EAE animals include stimulating substances elaborated by infiltrating lymphoid cells, and the generalized edema accompanying the demyelinative condition. The activation of GFAP protein staining and metabolism in EAE might serve as a model for the activated growth of astrocyte processes which cause the severe gliosis seen in multiple sclerosis.

Animals↗
PubMed1983

Degradation of glial fibrillary acidic protein by a calcium dependent proteinase: an electroblot study.

In situ and in vitro degradation of glial fibrillary acidic (GFA) protein in mouse spinal cord was examined with electroblots stained for GFA protein by the peroxidase anti-peroxidase method. Non-degraded, intact GFA protein had a molecular weight of 48 Kdaltons and isoelectric points ranging from pH 5.8 to 6.4. The molecular weights of immunoreactive degradation products ranged from 47 to 28 Kdaltons. All of the degradation products had acid shifted isoelectric points (pH 5.8-5.2). Degradation was prevented by chelating calcium with EGTA. In contrast to in situ degradation, degradation in vitro with 3 mM CaCl2 occurred at a faster rate. The effect of pH and temperature on the degradation process were determined by incubating homogenized spinal cords in 3 mM CaCl2 solutions varying in pH from 4 to 10 and at 4, 37, and 60 degrees C. The greatest number of immunoreactive bands with the lowest molecular weights occurred at pH 8 and 37 degrees C. The results suggest that turnover of glial filaments is in part controlled by a calcium dependent proteinase active near neutral pH similar to that postulated for neurofilament turnover.

Animals↗
PubMed1983

Glial fibrillary acidic protein synthesized in vitro using messenger RNA from a human glioma cell line.

Messenger RNA (mRNA) extracted from a continuous human glioma cell line grown in culture or as a solid tumor was translated in an mRNA-dependent reticulocyte lysate system. Translation products labeled with [35S]methionine were immunoprecipitated with antiserum specific for glial fibrillary acidic (GFA) protein, separated by one- and two-dimensional polyacrylamide gel electrophoresis and analyzed fluorographically. Immunoprecipitates from both cell culture and tumor mRNA translations had a molecular weight of 49,000 daltons, consistent with GFA protein extracted from human tissue. In two dimensions, the 49,000-dalton band resolved into two to three spots at pH 5.7-5.9, the isoelectric point of GFA protein. Minor lower molecular weight products were detected in fluorographs of heavily overloaded gels or in film exposed for extended periods of time. These data indicate that the GFA protein produced by this glioma cell line is chemically and immunologically similar to normal human GFA protein, which suggests that the primary phenotypic expression of GFA protein in this tumor cell line is not altered by the neoplastic process.

Cell Line↗
PubMed1983

Study of glial fibrillary acidic protein in a human glioma cell line grown in culture and as a solid tumor.

A continuous human glioma cell line grown in culture and as a solid tumor was analyzed for glial fibrillary acidic (GFA) protein. This material provided a rich source for GFA protein that could also be manipulated and controlled. Immunoperoxidase staining at the light and electron microscopic levels revealed that the cell culture and tumor specimens were strongly positive for GFA protein. When aqueous soluble fractions of the cell culture and tumor were separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, electroblotted onto nitrocellulose, and stained immunochemically, they contained exclusively low molecular weight (41--43K-dalton) GFA peptides. SDS (0.15%)-soluble fractions contained either low molecular weight only (culture) or a mixture of peptides ranging from 41 to 49K daltons. SDS (1%) extracts of either cell culture or tumor contained only 49K-dalton GFA protein. Two-dimensional gel separation revealed that the GFA protein extracted from either the culture or tumor with 1% SDS resolved to two or three spots at pH 5.8. Low molecular weight GFA peptides (less than 49K daltons) in aqueous and 0.15% SDS-soluble extracts became increasingly more acidic with decreasing molecular weight. The extremely rapid degradation seen suggests that this cell line may be a valuable system for further study of intermediate filament protein turnover.

Cell Line↗
PubMed1982

Glial fibrillary acidic protein synthesized in vitro using messenger RNA from jimpy mouse spinal cord.

Glial fibrillary acidic (GFA) protein was synthesized in vitro in a rabbit reticulocyte lysate system programmed with messenger RNA (mRNA) extracted from Jimpy mouse spinal cord. It was identical in molecular weight and charge to that synthesized from normal mouse mRNA and GFA protein extracted from normal mouse cord. These data suggest that the Jimpy mutation does not affect the primary phenotypic expression of GFA protein.

Animals↗
PubMed1982

An ultrastructural and immunocytochemical study of astrocytic differentiation in vitro: changes in the composition and distribution of the cellular cytoskeleton.

Astroglia in cultures of dissociated neonatal rat optic nerves were studied by light microscopy, immunocytochemistry and electron microscopy to determine whether intermediate filaments play a role in defining the multipolar morphology of the mature astrocyte. Immature, polygonal astroblasts contained few glial filaments, in spite of exhibiting positive staining with antiserum against glial fibrillary acidic (GFA) protein. Microtubules were the most prominent cytoskeletal component at early stages of cytodifferentiation, but these were progressively reduced in number at later intervals and were gradually replaced by intermediate filaments. These observations suggest that microtubules are involved in the initial establishment of cytoplasmic asymmetry and process development. Subsequently, glial filaments may play a role in maintaining and stabilizing the overall geometry of the mature astrocyte.

Animals↗