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Biomedical subjects

E Bock

Publications and source records attributed to E Bock.

At least 199 records · Page 11Linked to original sources
PubMed1981

Isolation of intermediate filaments from rat astrocytes in culture.

Intermediate filaments from rat astrocytes in culture were isolated by subcellular fractionation. The fractionation was monitored by electron microscopy and by quantitative immunoelectrophoresis using rabbit antibody directed against human glial fibrillary acidic protein (GFA). Morphologically intermediate filaments appeared helical with a mean diameter of 10 nm. Isolated filaments were disassembled at highly alkaline pH. After lowering of pH to slightly acidic values reassembled filaments, approximately 17 nm in diameter, were observed. As revealed by sodium dodecyl sulfate polyacrylamide gel electrophoresis the filament preparation was composed predominantly of a 51,000 molecular weight protein, corresponding to GFA. At high loads additional proteins of molecular weights 43,000 and 58,000 were detected. These latter proteins may represent residual actin and vimentin, respectively.

Animals↗
PubMed1981

Responsiveness of fetal rat brain cells to glia maturation factor during neoplastic transformation in cell culture.

The effect of partially purified extracts from adult pig brains containing a glia maturation protein factor (BE) has been investigated on neural cells during carcinogenesis. Pregnant BD IX-rats were given a single transplacental dose of the carcinogen ethylnitrosourea (EtNU) on the 18th day of gestation. The brains of the treated fetuses were transferred to cell culture and underwent neoplastic transformation with a characteristic sequence of phenotypic alterations which could be divided into five different stages. During the first 40 days after explantation (stage I & II) BE induced morphological differentiation of epitheloid neural cells into astrocytes. This occurred in carcinogen treated cells as well as in untreated control cultures. At the same time cells with astrocyte morphology showed accumulation of glial fibrillary acidic protein (GFA) as tested by indirect immunofluorescence with monospecific antibodies against GFA. Thereafter, in the EtNU pre-treated cultures an increased number of cells with astrocyte morphology was seen, and BE further increased the number of cells with long cytoplasmic processes. Control cells were GFA negative, while some few strongly, as well as many weakly, positive cells were seen after treatment with BE (stage III). At the later stages of neoplastic transformation the effect of BE became gradually less, and in tumourigenic cells which occurred after about 200-300 days, only a slight morphological change took place in a few cell lines. No appreciable effect on GFA-content was seen any longer, although some few weakly GFA positive cells could be observed in all permanent cell lines. Fetal rat brain cells therefore seem to become less responsive to this differentiation inducer during neoplastic transformation in cell culture.

Animals↗
PubMed1981

Xeroradiography of tenomuscular traumatic pathologic conditions of the limbs.

Due to its intrinsic technical features xeroradiography is particularly suitable for the documentation of soft tissue abnormalities. Indications and advantages of the method in the posttraumatic alterations of the tenomuscular system of the limbs are discussed. Several examples of acute or chronic diseases are presented. The authors prefer this technique to the traditional films in view of the obtainable graphic results; a better demonstration of the tenomuscular structures is obtained. Often comparison with the contralateral side is necessary; the performance of "functional' xeroradiograms is essential, especially in smaller lesions. Xerography is a useful complement of clinical examinations for an early diagnosis of lesions, for detection of clinically doubtful lesions and for the follow-up after treatment.

Achilles Tendon↗
PubMed1980

Quantitation of glial fibrillary acidic protein in human brain tumours.

The glial fibrillary acidic protein (GFA) content of 58 human brain tumours was determined by quantitative immunoelectrophoresis, using monospecific antibody against GFA. Astrocytomas, glioblastomas, oligodendrogliomas, spongioblastomas, ependymomas and medulloblastomas contained relatively high amounts of GFA, up to 85 times the concentration in parietal grey substance of normal human brain. GFA was not found in neurinomas, meningiomas, adenomas of the hypophysis, or in a single case of metastasis of adenocarcinoma. Non-glial tumours of craniopharyngioma and haemangioblastoma were infiltrated by reactive astroglia and showed considerable amounts of GFA.

Albumins↗
PubMed1980

Biochemical and ultrastructural studies of cultured rat astroglial cells: effect of brain extract and dibutyryl cyclic AMP on glial fibrillary acidic protein and glial filaments.

The growth of astroglial cells in primary cultures derived from newborn rat cerebral hemispheres was investigated in the absence and in the presence of newborn rat brain extract or dBcAMP. The parameters chosen were the content of DNA, total protein, and glial fibrillary acidic protein (GFA) as well as the morphologic development of gliofilaments. During the entire culture period the DNA content increased in control culture indicating a continuous cell division, whereas the cells stopped dividing after 14 or 4 days of treatment with either brain extract or dBcAMP respectively. In contrast, a constant increase of total protein was found in both control and treated cultures. Since cell divisions had stopped in treated cultures, the increase in total protein in these cultures indicates growth of the individual cells. The GFA levels increased progressively and similarly in control cultures and in cultures treated with brain extract. The values in the treated cultures remained slightly higher than those in controls. Conversely, immediately after the addition of dBcAMP a sudden increase in GFA protein occurred and the amounts were statistically significantly different from those of the controls. The GFA levels were expressed relative to total protein indicating that GFA constitutes an increasing amount of the total protein of the individual cells during culture. The changes in the amount of GFA was shown to parallel the morphologic development of gliofilaments. Indeed, when the level of GFA increased a progressive accumulation of gliofilaments was observed. The results obtained were discussed in relation to the astrocytic maturation.

Animals↗
PubMed1980

Nervous system-specific proteins in developing rat cerebral cells in culture.

The nervous system-specific proteins; synaptin, D1, D2, D3, glial fibrillary acidic protein (GFA) and 14-3-2, were quantified in dissociated cerebral cells from the foetal rat brain at various times of growth in culture. By approximately 1 week in culture, the neuronal membrane markers synaptin, D1, D2, and D3 could all be demonstrated. A maximum concentration of 10-20% for synaptin, D1, and D3 and 160% for D2, in comparison with the levels in adult forebrain, was attained during the 2nd week in vitro. The astroglial gliofilament marker GFA increased continuously, reaching by 38 days of cultivation an 18-fold higher level than the concentration in adult forebrain. The neuronal cytoplasm marker 14-3-2 could be demonstrated in trace amounts, and only after more than 1 week in vitro. Neuronal cell bodies and processes stained by indirect immunofluorescence using an anti-D2 serum were strongly fluorescent after 1 week in vitro. Immunofluorescence staining for GFA revealed a cytoplasmic filamentous network in perinuclear areas and processes of, presumably, astroblasts.

Animals↗
PubMed1979

Characterization of a membrane protein from cholinergic synaptic vesicles isolated from the electric organ of Torpedo marmorata.

Rabbits were immunized with cholinergic synaptic vesicles isolated from the electric organ of Torpedo marmorata. The resultant antiserum had one major antibody activity against an antigen called the Torpedo vesicle antigen. This antigen could not be demonstrated in muscle, liver or blood and is therefore, suggested to be nervous-tissue specific. The vesicle antigen was quantified in various parts of the nervous system and in subcellular fractions of the electric organ of Torpedo marmorata and was found to be highly enriched in synaptic vesicle membranes. The antigen bound to concanavalin A, thereby demonstrating the presence of a carbohydrate moiety. By means of charge-shift electrophoresis, amphiphilicity was demonstrated, indicating that the Torpedo vesicle antigen is an intrinsic membrane protein. The antigen was immunochemically unrelated to other brain specific proteins such as 14-3-2, S-100, the glial fibrillary acidic protein and synaptin. Furthermore, it was unrelated to two other membrane proteins, the nicotinic acetylcholine receptor and acetylcholinesterase, present in Torpedo electric organ. The antiserum against Torpedo synaptic vesicles did not react with preparations of rat brain synaptic vesicles or ox adrenal medullary chromaffin granules.

Acetylcholine↗
PubMed1979

Immunochemically identical hydrophilic and amphiphilic forms of the bovine adrenomedullary dopamine beta-hydroxylase.

By means of a monospecific antibody, dopamine beta-hydroxylase was monitored immunoelectrophoretically in various extracts of chromaffin granules. Approximately one-third of the dopamine beta-hydroxylase present was located in the membrane fraction and could only be liberated with detergent. The dopamine beta-hydroxylases of the buffer and membrane fractions were antigenically identical, but differed in their amphiphilicity, as demonstrated by the change in precipitation patterns on removal of Triton X-100 from the gel, on charge-shift crossed immunoelectrophoresis and on crossed hydrophobic interaction immunoelectrophoresis with phenyl-Sepharose. Furthermore, immunoelectrophoretic analysis in the presence of Triton X-100 plus the cationic detergent cetyltrimethylammonium bromide indicates additional heterogeneity of the membrane-bound dopamine-beta-hydroxylase. By limited proteolysis with chymotrypsin and thermolysin the amphiphilic form could be convered into its hydrophilic counterpart.

Adrenal Medulla↗
PubMed1979

Brain-specific proteins in the occipital cortex of rats housed in enriched and impoverished environments.

The occipital cortex was dissected from the brain of rats housed in either enriched or impoverished environment for four weeks. In environmentally enriched rats the weight of occipital cortex was found to be increased 5.7%, compared to environmentally impoverished rats, and the amount of protein was increased 6.0%. The amount of six nervous system-specific proteins was measured by crossed immunoelectrophoresis. Synaptin increased 4.7%, D3 increased 8.3%, and D1 increased 9.6%, whereas D2 was not significantly increased. Compared to D2, D3 and D1 were still increased significantly, although all were present in synaptosomal membrane fractions. The protein S-100 was increased 3.4% and the neuronal protein 14-3-2 was increased 12.2% for the cathodal component whereas the anodal component was not increased. The results were interpreted as representing delayed development of environment-dependent neurons in the environmentally impoverished rats.

Animals↗
PubMed1979

Deoxyribonucleic acid in Nitrobacter carboxysomes.

Carboxysomes were isolated from Nitrobacter winogradskyi and Nitrobacter agilis. The icosahedral particles contained double-stranded deoxyribonucleic acid (DNA). In the presence of ethidium bromide and cesium chloride, the particle-bound DNA had a buoyant density of rho 25 = 1.701 g/cm3. Electron microscopy revealed the DNA to be a 14-micron circular molecule.

Centrifugation, Density Gradient↗