Biomedical subjects
Publications and source records attributed to H G Bernstein.
Glucagon-like immunoreactivity was demonstrated in different parts of rat and sand rat central nervous system by the indirect immunofluorescence method. In hyperglycemic animals the level of immunoreactive material was reduced to a great extent.
Using immunofluorescence technique a positive reaction to insulin antiserum could be revealed in different parts of the CNS of Wistar rats and sand rats.
The hypothalamic and extrahypothalamic distribution of somatostatin-like immunoreactivity (SLI) was investigated in fed adult sand rats (Psammomys obesus) of both sexes using the immunofluorescence technique. Blood glucose and insulin concentrations were determined in these animals prior to decapitation. In a blind study, the amount of immunofluorescence of certain CNS areas and the glucose: Insulin ratio were compared and found to be connected: High amounts of SLI were detected in the dorsal hippocampus, in some hypothalamic nuclei and the median eminence of rats displaying low glucose levels. Sand rats with high blood glucose values did not show SLI in the hippocampal formation and the immunofluorescence of the circumventricular (hypothalamic) regions and the Eminentia mediana was drastically reduced. A possible correlation of SLI with insulin concentrations in the blood could not be revealed. The data obtained are discussed as a possible expression of a CNS influence on glucoregulation in this species.
Islets of Langerhans were investigated with the indirect immunofluorescence technique for somatostatin. Fluorescence was observed in cells which are by number and localization typical "D-cells". somatostatin-like immunoreactivity was also present in few cells of the exocrine part of pancreas.
Somatostatin-like immunoreactivity (SLI) was demonstrated in neurons of the dorsal hippocampus of the sand rat by means of the immunofluorescence technique.
This report describes the ultratopochemical localization of the thiamine pyrophosphatase in the pyramidal cells of the CA3 region of Wistar rat hippocampus. Attention was focussed on the occurrence of the enzyme out of the Golgi field. Thiamine pyrophosphatase was demonstrated in dendrites and - to a lesser extent - in axons. TTPase containing synapses were rather seldom and belonged to the axo-dendritic type. A hypothetic model concerning the transport and the distribution of the enzyme within the cell is presented.
The thiamine pyrophosphatase histochemical technique is believed to be a suitable approach to the selective staining of the Golgi vesicles of all animal cells, icluding the neuron. However, during the past decade a considerable number of data have been published, suggesting that the TPPase is in general a membrane-associated enzyme in the brain, which can be found in subcellular fractions other than Golgi lamellae. It has therefore become necessary to reconsider the view that thiamine pyrophosphatase is an exclusive marker enzyme of the Golgi apparatus.
The pattern and some substrates characteristic of the rat brain 5'-nucleotidase were studied using the isoelectric focusing technique, which revealed that the enzyme is present in a single form in hippocampus extracts. An alkaline phosphatase, which is also able to split nucleoside monophosphates, is not active at neutral pH values. The isoelectric points were found to be 6.4 +/- 0.1 for the specific 5'-nucleotidase and 6.8 +/- 0.1 for the phosphatase.
The fine structural localization of the 5'-nucleotidase was investigated in the CA3 region of the rat hippocampus. The attention was focussed on the occurrence of the enzyme in the synaptic region. The 5'-nucleotidase activity was demonstrated at the surface membranes of axons and dendrites. Prominent portions of enzyme activity were detectable in the nuclei and the nuclear envelope, whereas the cytoplasmic organelles were nearly devoid of reaction product. In synapses five types of 5'-nucleotidase localization were revealed. A participation of the enzyme in the process of neurotransmission is discussed.
The electron-microscopic localization of TDPase in the tanycytes of rat brain was studied. The reaction product was demonstrated in the membranes, but not in the Golgi apparatus of this cell type. Possible functional aspects of these findings were discussed.
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The effect of intracerebroventricularly applied insulin on one-trial learning passive avoidance behaviour has been studied in rats. Treatment with 10.3 pmole insulin 1 hr before the 24 hr retention test attenuated passive avoidance behaviour at both the 24 hr and 48 hr retention trials. The data suggest that insulin may play a role in processes relating to the retrieval of information stored in the brain.
The anatomical distribution of the neuronal calcium sensor proteins visinin-like protein-1 and -3 (VILIP-1 and -3) was investigated in various neocortical areas of Alzheimer's disease (AD) patients and controls. In AD and normal brains their cellular localization was confined to pyramidal and non-pyramidal neurons. In AD brains the intracellular immunostaining for VILIP-1 and to a lesser extent for VILIP-3 was found to be reduced in comparison to controls. Also, significantly less VILIP-1-immunoreactive neurons were found in the temporal cortex of AD patients as compared to normal brains. Accordingly, Western blot analysis revealed that immunoreactivity for VILIP-1 is less concentrated in tissue extracts of the temporal cortex of AD patients compared to controls. Extracellularly, VILIP-1 and VILIP-3 immunoreactive material was detected in close association with typical pathologic hallmarks of AD such as dystrophic nerve cell processes, amorphous and neuritic plaques, and extracellular tangles. In control brains an extraneuronal localization of VILIP-1 or VILIP-3 was never observed. Our morphological and neurochemical findings point to an involvement of these two neuronal calcium sensor proteins in pathology and possibly pathophysiology of changed calcium homeostasis in AD.
The neuroanatomical distribution of the proteinase kallikrein (EC. 3.4.21.35) in human brain was examined immunohistochemically by using antiserum against human tissue kallikrein. In normal nervous tissue only faint immunostaining of some neocortical and hippocampal neurons was observed. Glial cells were found to be immunonegative for kallikrein. In Alzheimer disease (AD) brains kallikrein-like immunoreactivity was associated, in some areas, with nerve cells and, especially in the neocortex, with numerous neuritic plaques. A possible function of the proteinase in AD-associated cascade of inflammatory response is supposed.