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Biomedical subjects

E ESSNER

Publications and source records attributed to E ESSNER.

At least 19 recordsLinked to original sources
PubMed1965

NUCLEOSIDE PHOSPHATASE ACTIVITIES IN RAT CARDIAC MUSCLE.

Localizations of aldehyde-resistant nucleoside phosphatase activities in frozen sections of rat cardiac muscle have been studied by electron microscopy. Activities are higher after fixation with formaldehyde than with glutaraldehyde. After incubation with adenosine triphosphate or inosine diphosphate at pH 7.2, reaction product is found in the "terminal cisternae" or "transverse sacs" of the sarcoplasmic reticulum, which, together with the "intermediary vesicles" (T system), constitute the "dyads" or "triads". Reaction product is also present at the membranes of micropinocytotic vacuoles which apparently form from the plasma membrane of capillary endothelial cells and from the sarcolemma. In certain regions of the intercalated discs, reaction product is found within the narrow spaces between sarcolemmas of adjacent cells and within micropinocytotic vacuoles that seem to form from the sarcolemma. With inosine diphosphate, reaction product is also found in other parts of the sarcoplasmic reticulum. After incubation with cytidine monophosphate at pH 5, reaction product is present in the transverse sacs of sarcoplasmic reticulum, in micropinocytotic vacuoles in capillary endothelium, and in lysosomes of muscle fibers and capillaries. The possible significance of the sarcoplasmic reticulum phosphatases is discussed in relation to the role the reticulum probably plays in moving calcium ions and thereby controlling contraction and relaxation of the muscle fiber.

Adenosine Triphosphate↗
PubMed1962

Cytochemical and electron microscopic studies of rat liver with reduced capacity to transport conjugated bilirubin.

ALTHOUGH THE LIVERS OF RATS TREATED WITH AGENTS KNOWN TO SUPPRESS BILIRUBIN TRANSPORT APPEARED RELATIVELY NORMAL ON ROUTINE HISTOLOGICAL SECTIONS, CYTOCHEMICAL AND ELECTRON MICROSCOPIC PREPARATIONS REVEALED MARKED CHANGES IN: (a) levels of alkaline phosphatase and apparent ATPase activities of the cell membrane at the sinusoids, bile canaliculi, and between adjacent cells; (b) morphology of the bile canaliculi such as dilatation, fragmentation, vesiculation and reduced numbers of microvilli; (c) the number of lysosomes and their distribution within the cell. Similar changes in the cytochemistry of the liver cell were induced by extrahepatic obstruction.

Bile↗
PubMed1961

Localization of acid phosphatase activity in hepatic lysosomes by means of electron microscopy.

Samples of liver from untreated rats, from rats infused with unconjugated bilirubin, and from biopsies of human liver were fixed overnight in cold formol-calcium. Frozen sections were stained for acid phosphatase activity by the Gomori lead-glycerophosphate procedure. Small blocks of fixed tissue were also incubated in this medium. These were then treated briefly with osmium tetroxide, dehydrated, and embedded in methacrylate. Thin sections were studied by electron microscopy. The sites of reaction product of acid phosphatase activity as visualized in electron micrographs are consistent with those seen in frozen sections studied by light microscopy. They indicate that the pericanalicular bodies of parenchymatous cells, the large spherical bodies of Kupffer cells, the microbodies appearing after bilirubin infusion and lipofuscin granules belong to the class of cytoplasmic organelles called lysosomes by de Duve.

Acid Phosphatase↗
PubMed1960

An electron microscopic study of erythrophagocytosis.

The present study describes a submicroscopic surface fragmentation of erythrocytes which occurs in the ascitic fluid of rats bearing the Novikoff ascites hepatoma. The resulting fragments attach to the surface of macrophages and are phagocytized by pseudopod formation. Plasma membrane in the region of these phagocytosis vacuoles appears to condense into electron-opaque material, suggesting an alteration in its physicochemical state. Stages in intracellular digestion of intact erythrocytes or small fragments within the phagocytosis vacuoles are illustrated; no particles resembling ferritin are observed. The phagocytosis vacuoles possess high levels of acid phosphatase activity. They may be called phagosomes, a type of lysosome. There is no indication of a connection between phagosomes and other formed cytoplasmic organelles. Small vacuoles of the order of 80 mmicro in diameter, which may represent pinocytosis vacuoles, are present in the cytoplasm and some appear to be in contact with the phagosome membrane, reminiscent of observations of Rose with HeLa cells.

Animals↗
PubMed1958

Adenosinetriphosphatase and 5-nucleotidase activities in the plasma membrane of liver cells as revealed by electron microscopy.

The sites of reaction product resulting from ATPase and 5-nucleotidase activities remaining in parenchymatous cells of osmium-fixed rat liver were studied by electron microscopy of thin sections. These indicate that both ATPase and 5-nucleotidase activities are localized in the plasma membrane where it folds to form the microvilli of the bile canaliculus, and that 5-nucleotidase activity is also present in the microvilli at the sinusoidal aspects of the cells. It is suggested that these enzymes, particularly ATPase, may play a role in molecular transport or in some kind of membrane activity at the cell surface. Of special interest is the apparent differential localization of these enzymes at the absorptive and secretory regions of the plasma membrane of the cell. It may be of interest to study changes in these enzyme localizations in pathologic states, as a sign of changed cell function. Some of the difficulties in the interpretation of enzyme reaction products seen in electron micrographs are discussed.

Adenosine Triphosphatases↗