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G Gombos

Publications and source records attributed to G Gombos.

At least 55 records · Page 3Linked to original sources
PubMed1985

A developmentally modified neurone-specific marker in rodent cerebellum.

Out of several monoclonal antibodies secreted by hybridomas resulting from the fusion of a mouse myeloma cell line with spleen cells from mice immunized with cerebellar membranes from 12 day old rats, one, called 11.9, produced an unusual immunolabelling pattern when tested on sections of rat cerebellum. The cerebellar distribution of the antigenic sites recognized by this antibody using an immunoperoxidase technique at the optical and ultrastructural levels is described in detail in this report. The immunoreaction product was found in the adult rat to be associated with the microtubules and the zone immediately beneath the plasma membrane of parallel fibres. In young animals the density of immunostaining appears to be higher than in the adult, and the staining is detectable in addition in the perikaryal cytoplasm of granule cells. Biochemical studies using the Western immunoblot technique demonstrate that the antigens consist of two polypeptides of molecular weights 120 and 185 kD. The possible relation of the antigens to cytoskeletal structures is discussed and the labelling pattern is compared with that produced by other known monoclonal antibodies.

Animals↗
PubMed1984

Monoclonal antibodies specific for glial and neuronal antigens in the young rat cerebellum.

Monoclonal antibodies from 15 different hybridomas derived from the fusion of mouse spleen cells with a myeloma cell line were selected. Mice were immunized with the particulate fraction from 10-13-day-old rat cerebella. Hybridoma secreting antibodies were screened simultaneously by both immunocytochemistry and binding assay. Each antibody reacts with specific cerebellar neuronal or glial cells and structures.

Animals↗
PubMed1984

Muscarinic receptor during postnatal development of rat cerebellum: an index of cholinergic synapse formation?

Quantitative and qualitative modifications of the specific binding sites for [3H]quinuclidinyl benzylate (QNB), a muscarinic antagonist, were studied during rat cerebellar postnatal development. Specific binding sites for QNB (QNB-sbs), regardless of whether they correspond to muscarinic acetylcholine receptors, are present with the highest density in the archicerebellar cortex, but the total amount per region is about the same in the archi -, paleo-, and neocerebellar cortex regions. Large amounts of QNB-sbs are also present in a cerebellar fraction including central white matter and deep cerebellar nuclei. QNB-sbs are low but present at birth and then accumulate during ontogenic development according to a curve which duplicates, with a delay of a few days, the curve of DNA accumulation. Dissection studies indicated that this curve does not depend on the preferential localization of QNB-sbs in a specific cerebellar region nor on the particular development of this region. The similarity of the QNB-sbs and the DNA developmental curves might indicate that the QNB-sbs are present on granule cells; however, a comparative analysis of the data in the literature suggests that a great many QNB-sbs are located on the Purkinje cell dendrites in the molecular layer, where all or some of them might correspond to the extrajunctional muscarinic acetylcholine receptor detected there by electrophysiology. It would appear that only a small percentage of cerebellar QNB-sbs corresponds to the cholinergic synapses present in cerebellar cortex; hence, the question of muscarinic receptors in the cerebellum should be re-examined.

Acetylcholinesterase↗
PubMed1983

Uptake and metabolism of L-[3H]glutamate and L-[3H]glutamine in adult rat cerebellar slices.

Using very low concentrations (1 mumol range) of L-2-3-[3H]glutamate, (3H-Glu) or L-2-3-[3H]glutamine (3H-Gln), we have previously shown by autoradiography that these amino acids were preferentially taken up in the molecular layer of the cerebellar cortex. Furthermore, the accumulation of 3H-Glu was essentially glial in these conditions. We report here experiments in which uptake and metabolism of either (3H-Glu) or (3H-Gln) were studied in adult rat cerebellar slices. Both amino acids were rapidly converted into other metabolic compounds: after seven minutes of incubation in the presence of exogenous 3H-Glu, 70% of the tissue accumulated radioactivity was found to be in compounds other than glutamate. The main metabolites were Gln (42%), alpha-ketoglutarate (25%) and GABA (1,4%). In the presence of exogenous 3H-Gln the rate of metabolism was slightly slower (50% after seven minutes of incubation) and the metabolites were also Glu (29%), alpha-ketoglutarate (15%) and GABA (5%). Using depolarizing conditions (56 mM KCl) with either exogenous 3H-Glu or 3H-Gln, the radioactivity was preferentially accumulated in glutamate compared to control. From these results we conclude: i) there are two cellular compartments for the neurotransmission-glutamate-glutamine cycle; one is glial, the other neuronal; ii) these two cellular compartments contain both Gln and Glu; iii) transmitter glutamate is always in equilibrium with the so-called "metabolic" pool of glutamate; iv) the regulation of the glutamate-glutamine cycle occurs at least at two different levels: the uptake of glutamate and the enzymatic activity of the neuronal glutaminase.

Animals↗
PubMed1983

A monoclonal antibody recognizing subpopulations of neurones in mouse brain.

A monoclonal antibody, designated C138, was raised against a particulate fraction from young postnatal mouse cerebellum. In sections from adult mouse brain and cerebellum, this antibody stained a sub-population of neurons. Cell bodies of large neurones and fibre tracts were negative in all brain regions examined, whereas neuropil was heavily labelled. Immune-electron microscopy confirmed the specificity of the antibody for certain types of neurones and indicated that the antigen may be associated with microtubular structures. Immunofluorescence studies on dissociated cerebellar cultures showed that the antigen was expressed inside all tetanus toxin-positive neurones but not by non-neuronal cells.

Animals↗
PubMed1982

Immunocytology of carbonic anhydrase II in the central nervous system of jimpy mutant mice.

In agreement with previous observations in rats, carbonic anhydrase II (CAII) demonstrated immunocytochemically with a specific immune serum, is exclusively localized in oligodendrocytes in the central nervous system of both normal and dysmyelinating Jimpy mutant mice. In spite of the lack of myelin, the CAII-containing cells in Jimpy mice are abundant. These data suggest that oligodendrocytes are formed in Jimpy mice but they are not able to reach an advanced stage of maturation as defined by their capacity for producing myelin.

Animals↗
PubMed1982

Monoclonal antibodies as neural cell surface markers.

A comparison is made of the immunohistochemistry at the ultrastructural level of three monoclonal antibodies directed against surface components of DNS cells. Hybridomas secreting these antibodies were obtained from two cell fusions of a rat myeloma cell line and immune splenocytes derived from rats immunized either with primary mouse brain cultured cells or membrane components. In cultures one antibody, anti-BSP2 (Brain Surface Protein-2), was preferentially directed against neurons while another, anti-BSP-3 (Brain Surface Protein-3), preferentially labeled astrocytes. In mouse cerebellar sections, both labeled the surface of Purkinje cells, granule cells and astrocytes. In addition a cytoplasm localization was apparent in granule cells and astrocytes. Another antibody anti-MESA-1 (Mouse Endothelial Surface Antigen-1) reacted exclusively with the surface of endothelial cells lining blood vessels. These data are discussed with reference to the biochemical nature of the corresponding antigens and to known glycoproteins of neural cell membranes.

Animals↗
PubMed1982

Immunoelectron microscopy of alpha 2-glycoprotein. An astrocyte-specific antigen.

The cellular and fine structural localization of the soluble brain-specific acidic alpha 2-glycoprotein was investigated using the indirect immunohistochemical method. The electron microscope was used to unambiguously identify cells containing the antigen. A single type of cell, the astrocyte, was found to be labelled with specific antisera directed against alpha 2-glycoprotein. Immunoperoxidase reaction product was found in astrocyte perikarya, their processes and perivascular end feet. It was found to be apparently associated with the cytoplasmic surface of mitochondria, reticular membranes and the plasma membrane. No specific labelling of neurones, oligodendrocytes, myelin or capillary endothelial cells was observed. The data is discussed in relation to the immunological properties of alpha 2-glycoprotein already reported.

Animals↗
PubMed1982

Cellular localization of the brain specific alpha 2-glycoprotein in rat cerebellum: an immunohistological study.

The cellular localization of the brain-specific, soluble, acidic alpha 2-glycoprotein was studied in rat cerebellum by using the immunoperoxidase technique at the light-and electron-microscopy levels with monospecific immune serum directed against this glycoprotein. Only astrocytes, their processes, and their end feet (subpial or perivascular) contained heavy immunoperoxidase reaction product. Cerebellar neurones, oligodendrocytes, myelin and blood vessel endothelia did not stain. Thus it appears that alpha 2-glycoprotein is an astrocyte marker.

Animals↗
PubMed1982

A new brain cell surface glycoprotein identified by monoclonal antibody.

Of 207 monoclonal antibodies produced against cultured mouse cerebellar cells, 16 reacted with cerebellar cell surfaces and 4 reacted with glycoproteins. One of them, called an anti-BSP-3 (Brain cell Surface Protein-3) defines a 48,000 molecular weight protein which can be iodinated at the surface of cultured cerebellar cells. Lectin-binding and sugar incorporation studies established the glycoprotein nature of the antigen. Astroglia (glial fibrillary acidic protein-positive cells) in primary cerebellar cultures were labelled intensely for this antigen by the indirect immunofluorescence method while neuronal cells and their processes were more weakly labelled. Fibronectin-positive cells were negative for BSP-3. In cerebellar sections using the immunoperoxidase method at both the optical and electron microscope levels, the difference in staining intensity between astrocytes and neuronal cells was not significant: in Purkinje cells and in the large neurones present in the deep cerebellar nuclei the immunoperoxidase percipitate was confined to the plasma, membrane while in both astrocytes and granule cells cytoplasmic labelling was also observed. Oligodendrocytes do not appear to react with the anti-BSP-3 monoclonal antibody; neither do endothelial or leptomeningeal cells. The availability of a monoclonal antibody produced by a stable hybridoma line will be a powerful tool in attempts to purify the BSP-3 antigen and to elucidate its function.

Animals↗
PubMed1982

L-glutamate and L-glutamine uptake in adult rat cerebellum: an autoradiographic study.

The compartmentation of L-glutamate in the central nervous system has been extensively studied and L-glutamine is believed to be the precursor of the neuronal releasable pool of the L-glutamate. In order to localize the sites of uptake of both L-glutamate and L-glutamine, autoradiography was used in tissue slices of adult rat cerebellum, where granule cells are considered to be glutamatergic. Incubation of the tissue with low concentrations of [3H]L-glutamate or [3H]L-glutamine produces in both cases a heavy labelling of the molecular layer. [3H]L-glutamate uptake seems to be essentially glial (Golgi epithelial cells and Bergmann fibres) while [3H]L-glutamine is more diffusely distributed over the molecular layer. Although no conclusions can be drawn on the nature of L-glutamine uptake, these results are in agreement with the model which considers L-glutamate uptake by glial cells to be the inactivating process of glutamatergic synapses.

Animals↗
PubMed1982

A surface marker for murine vascular endothelial cells defined by monoclonal antibody.

Spleen cells from a rat immunized with mouse cerebellar cells were fused with mouse myeloma cells. One of the hybridomas secreted a monoclonal antibody that reacts with a surface antigen on vascular endothelial cells. The antibody stained endothelial cells lining blood vessels in brain, heart, lung, kidney, and liver. It did not, however, stain endothelial cells lining hepatic sinusoids. Parenchymal cells were always negative. So far, an antigen of similar tissue distribution has not been described in the mouse and we have called it mouse endothelial surface antigen-1 (MESA-1). The antibody could be used as a highly specific usefulness for identifying endothelium-derived cells in culture has been demonstrated on cultures of dissociated mouse cerebellum, where it stained a subclass of fibronectin-expressing cells.

Animals↗
PubMed1981

Specific and artefactual cellular localizations of S 100 protein: an astrocyte marker in rat cerebellum.

Immunohistological techniques with specific antisera have been used to reinvestigate the problem of cellular localization of the neurospecific protein S100. In adult rat cerebellum, this protein is exclusively localized in astrocytes as shown by revealing in the same tissue secretion S100 protein and an oligodendrocyte marker, the isoenzyme II of carbonic anhydrase. The exclusive astroglial localization of S100 protein was confirmed by immuno-electron microscopy. A number of technical artefacts which may be at the origin of the claimed localization of S100 protein in neuronal cytoplasm and nuclei were also determined and described.

Animals↗
PubMed1981

A biochemical and immunohistological study of S100 protein in developing rat cerebellum.

Specific immune sera, one directed against S100 protein and one against glial fibrillary acidic protein (both proteins are specific astrocytic markers in rat cerebellum), were used in immunohistological methods to follow the formation and maturation of astrocytes during the postnatal development of rat cerebellum. Throughout development, S100 protein is detected only in astrocytes. Immunofluorescent Golgi epithelial cells and other astrocytes are detected in the cerebellum of newborn rat, their number increases rapidly between birth and the 10th postnatal day and then more slowly until the end of the 3rd week. In contrast, the increase in S100 protein level, measured in cerebellar homogenates by radioimmunoassay, was small until the 10th postnatal day. The greater accumulation subsequently found corresponds to an increase in the content of each astrocyte during the process of maturation.

Aging↗