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C Pilgrim

Publications and source records attributed to C Pilgrim.

At least 127 records · Page 7Linked to original sources
PubMed1981

[In vitro studies on the fixation dependent artifact formation in electron microscope autoradiography].

The binding of 14C-labeled L-fucose to bovine serum albumin by glutaraldehyde was investigated. Separation of protein-bound radioactivity from free precursor was performed either by TCA precipitation, thin layer chromatography or gel chromatography on Sephadex columns. For a positive control, [14C] fucose was replaced by [14C] leucine which has repeatedly been reported to be subjected to artifactual retention in glutaraldehyde-fixed tissue. It is shown that, under conditions where substantial amounts of free leucine are bound to albumin, radioactivity from L-[14C]fucose is not detectable in the protein fractions.

Autoradiography↗
PubMed1979

Incorporation of [3H]leucine into hypothalamic nerve and glial cells. A comparison by EM autoradiography.

Incorporation of L-[3H]leucine into the arcuate and supraoptic nuclei of rat and mice hypothalamus was studied by EM autoradiography at 30 min after intracerebral and intravenous application, respectively. The analysis applied provides information about (1) the distribution and (2) the concentration of radioactivity in the various tissue compartments, in particular nerve and glial cells. In the supraoptic nucleus, the proportion of radioactivity present in neuronal perikarya markedly exceeds that in the neuropil. Similar amounts of radioactivity in neuronal perikarya and neuropil were found for the arcuate nucleus. In both hypothalamic nuclei, only a small percentage of radioactivity is localized in glial cell bodies. However, the concentration of radioactivity in glial cells is nearly as high as in nerve cells and is lowest in the neuropil. Furthermore analysis of the subcompartments of the neuropil reveals that a considerable proportion of its radioactivity can be attributed to astrocytic processes. Conditions are discussed under which grain densities can be taken as measurements of relative synthesis rates of proteins. The results which are at variance with earlier autoradiographic studies are largely consistent with those of more recent biochemical studies on brain tissue separated into neuronal and glial fractions.

Animals↗
PubMed1979

Metabolism of glycoconjugates in hypothalamic neurons and glial cells: comparison of incorporation of [3H]fucose and [3H]N-acetylmannosamine by electron microscopic autoradiography.

Incorporation of two glycoconjugate precursors, [3H]fucose and [3H]N-acetylmannosamine, in the arcuate nucleus of the rat hypothalamus is compared 30 min after intraventricular administration. Electron microscopic autoradiographs were analyzed by a sampling technique which provides information about (i) the distribution of radioactivity in the tissue, (ii) the relative volumes, and (iii) the amount of radioactivity per unit volume of the various tissue compartments. With both precursors, the highest incorporation was found in glial cell bodies, being about five to six times that of neurons. This holds true for all three types of glia. The concentration of radioactivity in the neuropil consisting of neuronal and glial processes was exceedingly low, although, due to its large volume, it contained the highest fraction of total tissue radioactivity. The limitations imposed on the interpretation of the data in terms of synthesis of fucosyl- and sialoglycoconjugates are discussed. It is proposed that the observations support the concept that high rates of synthesis for glycoproteins (and possibly gangliosides) are a characteristic metabolic property of glial cells.

Animals↗
PubMed1979

A system of cells in the unstimulated rat brain characterized by preferential accumulation of [3H]deoxyglucose.

An autoradiographic technique using cryostat sections is described which permits visualization of a system of small, probably glial cells accumulating 2-[3H]deoxyglucose (2-[3H]DG). These cells are localized mainly in periventricular regions and in certain parts of white matter. Deoxyglucose uptake of these cells is not influenced by various experimental conditions. An attempt to demonstrate by this technique activation of hypothalamic neurosecretory centers following water withdrawal for 3 days was unsuccessful.

Animals↗
PubMed1978

A microprobe analysis of Gomori-positive glial cells in the rat arcuate nucleus.

Astrocytes and microglial cells in the arcuate nucleus of the rat hypothalamus contain lipofuscin-like granules which react with chrome alum gallocyanin and exhibit endogenous peroxidase activity. These granules were assessed with energy dispersive X-ray microanalysis and compared to neuronal dense bodies and glial cytoplasm. The granules are distinguished by a consistent content of sulphur and a frequent presence of calcium. The localization of other elements such as iron, copper, potassium and chlorine is impaired by methodical difficulties. The sulphur content as well as the endogenous peroxidase activity is interpreted as indicating a special variant of lipofuscin. The presence of calcium is discussed with respect to recent concepts of glia as a regulator of the ionic environment of the CNS.

Animals↗
PubMed1978

Labelling of human resting lymphocytes by continuous infusion of [3H]thymidine. I. Characterization of cytoplasmic label.

After continuous 3H-TdR infusion in vivo or incubation with 3H-TdR in vitro human blood lymphocytes were examined by light-microscopic and electron-microscopic autoradiography. Using relatively long autoradiographic exposure times (50--300 days) not only nuclear but also cytoplasmic labelling was visualized, the cytoplasmic label being present in up to 96% of the cells. The cytoplasmic label was predominantly associated with the mitochondria and was removed from the cells nearly completely by treatment with DNase but not with RNase or cold perchloric acid. It is concluded that this cytoplasmic label mainly represents 3H-TdR incorporated into mitochondrial DNA which is continuously renewed in an average turnover time of 14 days or less. This value is compatible with a turnover time of 11 days for mitochondrial DNA in mammalian cells reported in the literature.

Autoradiography↗
PubMed1977

Incorporation of 3H-fucose into nerve and glial cells: assessment by electron microscopic autoradiography.

Incorporation of 3H-fucose into hypothalamic tissue of rats was studied between ten minutes and seven days after intraventricular injection. In EM autoradiographs grain densities over perikarya of neurons, astro-, and oligodendroglia, and neuropil were evaluated. Grain densities were consistently higher over both types of glial cells as compared to neurons. The glia/neuron ratio was especially high after short experimental intervals and declined with increasing time intervals. Concomitantly there was an increase of grain density over the neuropil. The discussion concentrates on the methodical aspects which have to be considered in interpreting the autoradiographic data. It is concluded that both astroglia and oligodendroglia exhibit a considerably higher synthesis rate of glycoproteins per unit volume than nerve cells. The implications of the results for the interpretation of biochemical data on glycoprotein metabolism of brain tissue are discussed.

Animals↗
PubMed1977

[Electrophoretic separation and properties of acid phosphatase isoenzymes from rat brain (author's transl)].

Following agar gel electrophoresis of the 20 000 X g supernatant of rat brain homogenate a single band with acid phosphatase activity could be visualized by means of azo dye techniques. By adding Triton X-100 to the homogenate, a second band with enzymatic activity was demonstrable. A third isoenzyme could be identified in the presence of zinc ions. A fourth band visible only when employing lead methods has to be considered an artefact as its appearance does not depend on the presence of a substrate. The substrate specificity of the isoenzymes and the possibilities of influencing their activity were examined. By specific choice of substrates and effectors, conditions could be defined rendering possible a selective identification of the individual isoenzymes.

Acid Phosphatase↗
PubMed1975

Glycoprotein metabolism in the hypothalamus of rat: significance of glial cells.

Incorporation of 3H-fucose injected into the CSF was studied in hypothalamus and hypophysis of rats by biochemical and autoradiographic techniques. The concentration of radioactivity was determined as a function of time from 10 minutes to 28 days in the acid soluble and the acid precipitable fraction of homogenates. The incorporated activity was localized by light microscopic autoradiography in several regions of the hypothalamus. The labelled proteins were transported to the pars nervosa at a velocity of 1.1 to 3.3 mm/hr, i.e. in the fast component of the axoplasmic flow. Differences were found between hypothalamic and pars nervosa tissue regarding rates of increase and maximum concentrations of protein-bound radioactivity. Values for both parameters were about 6 times higher in hypothalamus than in pars nervosa. On the basis of the autoradiographic observations it is concluded that this difference may be due to a considerably higher synthesis rate of glycoproteins in glial cells than in neurons.

Animals↗