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Biomedical subjects

H G Bernstein

Publications and source records attributed to H G Bernstein.

At least 19 recordsLinked to original sources
PubMed1992

Hippocampal mossy fiber distribution does not correlate with two-way active avoidance performance in backcross lines derived from inbred mouse strains DBA/2 and C3H.

To elucidate the relation of genetically induced variations in two-way active avoidance performance and the extent of the hippocampal infra/intrapyramidal mossy fiber system (IIP-Mf) in inbred mouse strains DBA/2 (high performance, small IIP-Mf) and C3H (low performance, large IIP-Mf) we investigated a backcross line containing the DBA/2-derived genetic determinants for high avoidance performance in a C3H background. In the seventh backcross generation variations in performance analogous to the original strains were observed whereas the extent of mossy fibers was nearly homogeneous. This result suggests that both variables are determined by separate genetic factors at least in these strains and that differences in mossy fiber distribution are not an essential prerequisite for different active avoidance performance.

Afferent Pathways↗
PubMed1992

Aminopeptidases in the circumventricular organs of the mouse brain: a histochemical study.

The localization of four membrane-bound aminopeptidases--aminopeptidase A, aminopeptidase M, dipeptidylpeptidase IV, and gamma-glutamyl transpeptidase--known as characteristic enzymes of the blood-brain barrier was studied in the microvasculature of some circumventricular organs of the mouse brain (subfornical organ, area postrema, choroid plexus, and neurohypophysis). Enzyme activities were demonstrated histochemically in chloroform-acetone-pretreated cryostat sections applying an azo-coupling method. Reactions were evaluated using light microscopy and end-point microdensitometry. The results revealed differences in microvascular enzyme pattern between circumventricular organs and regions having a blood-brain barrier. Moreover, the cytochemical picture of the circumventricular organs themselves was not uniform. Dipeptidylpeptidase IV reaction showed a strongly reduced activity in the microvessels of all studied circumventricular organs. On the other hand, aminopeptidase M seemed to be present in both the leaky and the tight capillaries. Only a low activity of aminopeptidase A was found in parts of the choroid endothelium and the subfornical organ microvasculature. gamma-Glutamyl transpeptidase could neither be detected in the capillary part of the choroid plexus nor in the neurohypophysis. We are led to conclude that at least dipeptidylpeptidase IV might be involved in special mechanisms of the blood-brain barrier.

Aminopeptidases↗
PubMed1992

Histochemistry of guanylate cyclase, phosphodiesterase, and NADPH-diaphorase (nitric oxide synthase) in rat brain vasculature.

The distribution of guanylate cyclase, phosphodiesterase, and NADPH-diaphorase [nitric oxide (NO) synthase] was studied in rat brain both at the light and electron microscopic level with special emphasis on the vascular system. We showed that the cGMP-generating enzyme is located in cells (glial cells and pericytes) surrounding cerebral vessels, but not in the endothelium. For NO synthase, a dual localization was observed. The enzyme is present in parts of the endothelium and in nerve endings apparently innervating larger brain vessels. We propose, therefore, that NO acts on guanylate cyclase both from a "synaptic" and endothelial source.

Amino Acid Oxidoreductases↗
PubMed1992

Lysosomal proteinases as putative diagnostic tools in human neuropathology: Alzheimer disease (AD) and schizophrenia.

The cathepsin B, D and L were studied by immunohistochemical techniques in the human postmortem brain. The enzyme were primarily localized in neurons. Makroglial cells were seldom immunostained. It is shown that cathepsins B and D frequently occur in neuritic plaques of Alzheimer victims, thereby raising the question, whether or not cathepsin immunohistochemistry is a useful tool in the diagnosis of this disease. Furthermore, we identified certain glial cells to be immunoreactive for cathepsins in schizophrenics.

Aged↗
PubMed1991

Ornithine decarboxylase in reversible cerebral ischemia: an immunohistochemical study.

Anesthetized Mongolian gerbils were subjected to 5-min ischemia and 8 h of recirculation. Vibratom sections were taken for studying changes in ornithine decarboxylase (ODC) immunoreactivity using an antiserum to ODC, and tissue samples were taken for measuring ODC activity. After 5-min ischemia and 8-h recirculation ODC activity increased 11.5-, 5.9-, and 7.9-fold in the cerebral cortex, striatum and hippocampus, respectively (P less than or equal to 0.05 to 0.01). In the cortex, striatum and hippocampus of control animals immunoreactivity was low but clearly above the detection limit. The reaction was confined to neurons. After 5-min ischemia and 8-h recirculation a sharp increase in immunoreactivity was observed confined to neurons, indicating that the postischemic activation of polyamine metabolism is a neuronal response to ischemia. The immunoreactivity was markedly increased in the perinuclear cytoplasm and the dendrites. In the striatum the density of neurons exhibiting a sharp increase in immunoreactivity was more pronounced in the lateral than in the ventral part. In the hippocampus a strong reaction was present in all subfields but the CA1 subfield was particularly affected. The present study demonstrates for the first time that biosynthesis of a protein is markedly activated during the first 24 h of recirculation after 5-min cerebral ischemia of gerbils even in the vulnerable CA1 subfield, in which the overall protein synthesis is sharply reduced at the same time. Studying polyamine metabolism after ischemia may, thus, provide new information about the basic molecular mechanisms responsible for the altered gene expression after metabolic stress.

Animals↗
PubMed1991

Second messenger enzymes in glial cells: a cytochemical point of view.

Knowledge about second messenger metabolizing enzymes in neuroglia is still rather fragmentary. Therefore, the aim of the present investigation was to localize adenylate cyclase, guanylate cyclase, cyclic nucleotide phosphodiesterase and protein kinase A in glial cells of the rat hippocampus and cerebellum. Enzyme histochemical and immunohistochemical methods were used to detect the enzymes at the light and electron microscopic level. Astroglial cells were found to contain all 4 enzymes. Especially the microvascular glial cell processes were reactive. Oligodendroglial cells were only stained for adenylate cyclase acticity. Intracellularly, microtubules and intracellular membranes were frequently stained. The results point to the regulation of glial cell metabolism and of transport processes by cyclic nucleotides.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1991

Pattern of NADPH-diaphorase active neurons in rat forebrain is unchanged after pentylenetetrazol kindling.

The activity of NADPH-diaphorase in rat telencephalic structures has been revealed by use of a histochemical method. Multiple neurons belonging to different nuclei were found to contain the enzyme. Furthermore, diaphorase reactive nerve fibres and terminal fields were observed to be widely distributed throughout rat brain. Chemical kindling induced by pentylenetetrazol (PTZ) did not effect the regional distribution and cellular localization of the enzyme in the rat CNS.

Animals↗
PubMed1991

Ultrastructural study of cathepsin B immunoreactivity in rat brain neurons: lysosomal and extralysosomal localizations of the antigen.

Cathepsin B was localized in multiple neurons of the rat central nervous system by means of the peroxidase-antiperoxidase technique and immunogold labeling using a polyclonal antiserum produced in rabbits against rat liver enzyme. The main intracellular locus of cathepsin B antigenic sites was in lysosomes. In some cases, however, immunoreactive material was also detected outside lysosomes (i.e. at the membranes of the rough endoplasmic reticulum). The findings are discussed with respect to the proposed role of the enzyme in the general protein metabolism of the brain and the potency of the antiserum to label the proform of cathepsin B.

Animals↗
PubMed1991

Quantitative morphological analysis of hippocampal structures in DBA1 and DBA2 inbred mice strains with genetically determined different shuttle box behavior: the mossy fiber system with reference data to the C3H strain.

The present work deals with morphological aspects which are likely related to a genetically determined learning behavior in the shuttle box paradigm. Subregions of the hippocampal mossy fiber system in two closely related inbred mice strains, DBA1 as a bad active avoider and DBA2 as a good one, are compared. Additionally, data derived from C3H (bad active avoider) studies are analyzed. Beside of certain structural similarities in DBA1 and DBA2 such as the elongation of infrapyramidal mossy fibers along the CA3 neurons this study pays attention to the topography of hilus and basal CA3 mossy fiber innervation.

Animals↗
PubMed1991

Ornithine decarboxylase immunoreactivity in the pituitary gland. A comparative lightmicroscopical study.

In the present study efforts are made to localize ornithine decarboxylase enzyme protein--the key enzyme of polyamine biosynthesis--in the adenohypophysis of different vertebrates by means of immunocytochemistry. The antigenic expression of ornithine decarboxylase was revealed in the pituitary of the clawed frog (Xenopus laevis D.), but not in rat and human adenohypophysis. The immunocytochemical results are compared with the staining pattern of the periodic acid-Schiff-reaction. No correlation between these results and the immunocytochemically obtained data has been found. Conclusions are drawn from the location of the enzyme and possible phylogenetic and humoral regulation mechanism.

Animals↗
PubMed1990

Antigenic expression of cathepsin B in aged human brain.

The lysosomal thiol proteinase, cathepsin B, has been localized in different regions of aged human brain by use of the peroxidase-antiperoxidase technique. Cathepsin B-immunoreactive material was detected in multiple neurons of human hippocampus, neocortical area A 10, prefrontal gyrus and nuc. basalis of Meynert as well as in single white matter astrocytes. In brains of Alzheimer disease-affected subjects cathepsin B was revealed in neuritic plaques too. Possible functional consequences with regard to normal aging, neuropeptide metabolism and pathological changes are discussed.

Aged↗
PubMed1989

Cell type-specific distribution of cathepsin B and D immunoreactivity within the rabbit retina.

The cellular localization of cathepsin B and D immunoreactivity was demonstrated at the light microscopic level in the retina of adult rabbits by use of the peroxidase-antiperoxidase technique. Antisera were raised against rat liver enzymes. Whereas cathepsin D immunoreactivity was confined to Müller (glial) cells, cathepsin B was demonstrated in some, but not all, neuronal cell types. It is proposed that the two enzymes might carry different functions within the neuronal versus glial compartment.

Animals↗
PubMed1989

Immunodetection of cathepsin D in neuritic plaques found in brains of patients with dementia of Alzheimer type.

The aspartic endopeptidase cathepsin D was immunolocalized in 21 human cadaver brains from patients with dementia and controls. Immunoreactive cathepsin D was found to be present in multiple neurons, neuritic plaques, some macroglial cells, and microvessels. It is suggested that the enzyme might be involved in certain posttranslational changes of cystoskeletal compounds that lead to the formation and/or further growth of neuritic plaques and neurofibrillary tangles.

Aged↗
PubMed1989

Cathepsin B immunoreactive neurons in rat brain. A combined light and electron microscopic study.

The regional distribution and cellular localization of the lysosomal proteinase cathepsin B was studied by use of monospecific antiserum. The application of the peroxidase-antiperoxidase technique at the light microscopic level revealed cathepsin B immunoreactive neurons in many brain areas. A strong immunoreaction was found in pyramidal cells of the cortex, large neurocytes of the septal region, some hippocampal neurons and magnocellular nerve cells of the hypothalamus. Immunogold labeling on ultrathin cryosections of rat neocortex revealed the enzyme protein to be associated with lysosomes.

Animals↗
PubMed1988

Cystatin C containing neurons in human postmortem hypothalamus.

The regional distribution and cellular localization of cystatin C in neurons of human postmortem hypothalamic was studied by use of peroxidase-anti-peroxidase technique. Cystatin C (earlier named gamma-trace) was found to be present in multiple nerve cells belonging to nuclei supraopticus, paraventricularis and arcuatus. We speculate that the occurrence of cystatin C in human cerebrospinal fluid is the result of a release of the protein from these neurons into the ventricular system.

Aged↗