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Biomedical subjects

M Zaviacic

Publications and source records attributed to M Zaviacic.

At least 91 records · Page 5Linked to original sources
PubMed1979

Morphologic changes in the gastric mucosa of rats after administration of N-methyl-N'-nitro-N-nitrosoguanidine. Electronmicroscopic study.

Electron microscopic findings of the effects of exposure to the cancerogenic substance N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) upon the gastric mucosa of rats are presented. MNNG was administered in drinking water at a concentration of 83 mg/l over a period of eight weeks. The resulting findings included occurrence of myelin figures in membrane structures of epithelial cells, occasional disappearance of nuclear membrane, numerous intranuclear cytoplasmic pseudoinclusions, and increased number of perichromatin and interchromatin granules and of nuclear corpuscles. Narrowing of the layer of peripheral condensed chromatin and broadening of the layer of dispersed chromatin were frequently observed. In the cytoplasm of epithelial cells, production of autophagous vacuoles was detected in differentiated types of cells, the presence of great amount of polysomes and profiles of rough endoplasmic reticulum diversely deformed was seen in the undifferentiated neck cells. These cells presented a marked proliferative activity. Some of the changes described in the nuclei of epithelial cells were also observed in different mesenchymal elements in the lamina propria mucosae. The demonstrated changes are indicative of both regressive and progressive effects of the cancerogen used in our experiment.

Animals↗
PubMed1979

[Morphology of systemic anaphylactic reaction in rabbits to bovine serum albumin and ferritin. I. Manifestations of the reaction after antigen administration: laboratory, macroscopic and optical microscopic findings].

A report is presented on systemic anaphylactic reaction [SAR] of rabbits to bovine serum albumin and ferritin. Active anaphylactic sensibilization with a high yield of sensibilized animals was achieved by administering antigens to rabbits aged a few hours up to 3 months. Tre rabbits showed no presence of precipitins in the circulation, but there were reagins against bovine serum albumin or ferritin. There were various types of SAR activity. Macroscopic findings showed acute emphysema and signs of right heart overload. Apart from acute pulmonary emphysema, histology showed occasional bronchospasm and certain manifestations of RES activation as there was evidence of oedematous infiltration of the peribronchial and perivascular spaces. The above morphological findings cannot as yet be regarded as pathognomonic for SAR.

Anaphylaxis↗
PubMed1978

Influence of autolysis on rat gastric endocrine cells. Histochemical and electron microscopical study.

In the present study histochemical parameters of the rat gastric endocrine cells were followed up in the course of 24-h autolysis, and their ultrastructure was studied during autolysis lasting for 60 min. The autolysis occurred at 37 degrees C. In the light microscope, with the histochemical methods applied, only EC, ECL and G cells could be identified during the one-hour autolysis. With the autolysis proceeding for 6 and 12 h, only argyrophil method according to Grimelius (1968) enabled visualization of gastric argyrophilic cells. After 24 h of autolysis, none of the methods applied (not even the Grimelius method) proved to be adequate for successful demonstration of the gastric endocrine cells. In the course of 60-min autolysis, electron microscopic examination provided identification of the EC, ECL, AL, D1, and G cells with the characteristical ultrastructural appearance of granules. The granules of the endocrine cells (G cells included) were found to be considerably resistant to autolysis. The effect of 60-min autolysis did not induce granule "emiocytosis" or dissolution of granule content. Autolysis exceeding five minutes resulted in damage of the mitochondria of different degrees and in dilatation of the profiles of endoplasmic reticulum (particularly in G and AL cells). The results obtained in the present study demonstrate the feasibility of in vitro experimental stimulation since the endocrine granules have proved to be resistant to the effects of simultaneously developing autolysis.

Animals↗
PubMed1978

Experimental ultrastructural study on stimulation of the rat gastric endocrine cells. In vitro distension of the stomach by air inflation.

The effect of distension of the stomach by air (in vitro) upon the ultrastructural picture of gastric endocrine cells in rats starved for 72 hours was investigated. Distension of the stomach by air in vitro, lasting for 5, 10, 15 and 20 minutes, resulted in massive dissolution of gastrin granules that had accumulated in the course of starvation. In AL, D1, EC and ECL cells distension of the stomach by air failed to induce dissolution of granular content or release of granules by any other mechanism. In AL and D1 cells accumulation of secretory granules caused by starvation was observed, the ultrastructure of EC and ECL cells remained unchanged both under the effect of starvation and distension. Dilatation of endoplasmic reticulum profiles as well as other changes on some cell organelles observed on endocrine cells after distension of the stomach by air in vitro are due to the effect of autolysis.

Air↗
PubMed1978

Circadian rhythms of oxidoreductases in the rat gastric mucosa. Histochemical study.

Examination of selected oxidoreductases (succinate dehydrogenase, mitochondrial glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, NADH tetrazolium reductase) in the rat gastric mucosa revealed diurnal fluctation of enzyme activities with the most marked manifestation in succinate dehydrogenase. The maximum enzymatic activity found at 18.00 h and 24.00 h) points to the highest oxidoreductase capacity in the parietal cells just at the time when a rat usually expresses spontaneously the highest interest in food intake. The high activity of succinate dehydrogenase and other enzymes at that time is very likely the expression of a "fixed" metabolic adaptation of the parietal cells to the elevated production of hydrochloric acid, in connection with its role in the digestion of food in the stomach. The low enzymatic activity of most rat parietal cells during the day may represent the picture of "a resting afunctional".

Animals↗
PubMed1977

Histochemistry and cytochemistry of thiamine pyrophosphatase (TPP-ase 3.6.1.) in the rat gastric mucosa.

The paper deals with the histochemical and cytochemical distribution of thiamine pyrophosphatase (TPP-ase 3.6.1.) in the normal rat gastric mucosa using the method of NOVIKOFF and GOLDFISCHER (1961). In light microscopy, activity was demonstrated only in the GOLGI apparatus of the foveolar mucous cells; in the other specialized gastric mucosal cells no activity was established. At electron microscopic level, the reaction product was localized in the membranes of the cisternae of the GOLGI apparatus of foveolar mucous cells, undifferentiated neck cells, parietal cells, chief cells and in endocrine cells. The reaction product was not found in the endoplasmic reticulum of any of the above mentioned types of cells with the exception of parietal cells. The deposits of the reaction product in the cytoplasmic membrane, in the capillary endothelium and on the surface of the plasma membrane of foveolar mucous cells represents the sites of activity of alkaline phosphatase. The examination of the TPP-ase in the gastric mucosa inables us to estimate the activity of the GOLGI apparatus of gastric mucosal cells in the norm and in different pathological conditions connected with its changes.

Animals↗
PubMed1977

[Ultrastructure of the red pulp of the spleen in various thrombocytopenias].

The authors describe 10 cases of samples of spleen tissue obtained from patients with various thrombocytopenias which had been subjected to electron microscopical examinations. In splenomegalies associated with liver cirrhoses a certain proportion of platelets accumulated in the spleen, whereas others were ingested by macrophages. No significant polymorhism of the platelets was observed. In cases of idiopathic thrombocytopenic purpura marked polymorphism of the platelets as regards size and structure was observed. The platelets also showed a concoisuous relation to the polymorphonuclear laucotytes. The alterations of the inner structure of the platelets could not be regarded as specific, because they were also found in lymhogranuloma.

Humans↗
PubMed1977

[Ultrastructure of the red pulp of the spleen in various anemias].

Eighteen tissue samples of human spleens obtained from patients suffering from hereditary sphaerocytosis, acquired haemolytic anaemia, hypersplenism, Banti's syndrome and extralienal neoplastic disease were subjected to electron microscopical examinations. Lesioned erythrocytes were removed with the aid of the macrophages of the red pulp and in cases of a high number of injured erythrocytes the cells lining the sinuses were also involved. The proliferation of collagen connective tissue was possibly also involved in injuring the blood cells. The spleens obtained from patients with neoplastic disease not affecting the spleen could not be regarded as normal.

Anemia↗
PubMed1976

Histochemical findings in the rat gastric mucosa during starvation.

The influence of starving on the activity of enzymes of the rat gastric mucosa was investigated by selected histochemical methods. Beside the conventional methods of enzymatic histochemistry the technique of semipermeable membranes was used in the proof of lysosomal enzymes. Dehydrogenases were proved in aqueous and also in gel media with PMS. During the starvation in the parietal cells a marked increase took place in the activity of acid phosphatase, E-600 resistant esterase, less in beta-glucuronidase. High activity of the lysosomal enzymes in macrophages did not change during starvation. Nor did any changes took place in the activity of alkaline phosphatase in the endothelium of the capillaries. The chief cells in the control and starving animals, in contrast to the human gastric mucosa, did not contain any non-specific esterase. Concerning dehydrogenases, parietal cells with a different activity of these enzymes were observed both in starved and control animals. In the rat gastric mucosa starving induced changes in the activity of the enzymes which mark important organelles of the cells. Thus it is possible to consider the observed histochemical changes as a functional manifestation of morphological damage of cellular structures which are affected during starvation.

Acetylglucosaminidase↗
PubMed1976

Histochemical localization of enzymes in the normal rat gastric mucosa using the technique of the semipermeable membranes and the other methods.

In the paper we observed histochemically the distribution and activity of 16 enzymes in the normal rat gastric mucosa. The lysosomal enzymes were demonstrated by the method of semipermeable membranes (LOJDA 1972). At the proof of dehydrogenases aqueous and gel media were used. The parietal cells of the gastric mucosa contained a moderate activity of acid phosphatase, E-600 resistant esterase, and only a very slight activity of beta-glucuronidase and N-acetyl-beta-D-glucosaminidase. The macrophages of the interstice contained a high activity of beta-glucruonidase, acid phosphatase, E-600 resistant esterase and a low activity of N-acetyl-beta-D-glucosaminidase. The chief cells of the rat gastric mucosa, in contrast to the human, did not contain nonspecific esterase and also in them acid phosphatase was mostly lacking. The alkaline phosphatase was found only in the endothelium of the capillaries of the gastric mucosa. The parietal cells contained high activities of succinate dehydrogenase, alpha-glycerophosphate dehydrogenase, beta-hydroxybutyrate dehydrogenase, NADH tetrazolium reductase, a lower activity of NADPH tetrazolium reductase, as well as other soluable dehydrogenases. At the examination of dehydrogenases using aqueous as well as gel media with PMS during optimal short incubation periods, we found more and less active forms of parietal cells. The different oxidoreductase capacity of parietal cells in normal rat gastric mucosa can point to their unequal-functional load at the production of hydrochloric acid. The findings obtained are compared with the findings in older papers concerning different experimental animals and with the distribution of enzymes in the human gastric mucosa.

Acetylglucosaminidase↗