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A B NOVIKOFF

Publications and source records attributed to A B NOVIKOFF.

At least 37 records · Page 2Linked to original sources
PubMed1960

The localization of enzyme activities in the rat brain.

Studies with rat brain illustrate the usefulness of formol-calcium-fixed tissue for studying both enzymatic "chemoarchitectonics" and intracellular organelles. Unembedded frozen sections and polyvinyl alcohol-embedded sections may be used to demonstrate the activities of DPNH-tetrazolium reductase localized in mitochondria and ergastoplasm, TPNH-tetrazolium reductase localized in mitochondria, ATPase (and/or apyrase or ADPase) in cell membranes, and acid phosphatase in lysosomes.(1) Among the observations recorded are: (1) the presence of lysosomes in all cells of the brain; (2) the presence of numerous large lysosomes near the nuclei of capillary endothelial cells; (3) a polarized arrangement of large lysosomes in epithelial cells of the ependyma and choroid plexus; (4) the presence of ATPase activity in the cell membranes of some neurons; (5) the presence of either an apyrase or combination of ATPase and ADPase in the cell membranes of neuroglia and capillaries; (6) the presence of both DPNH- and TPNH-tetrazolium reductase activities in neuroglia; (7) the presence of DPNH- and TPNH-tetrazolium reductase activities in mitochondria and of DPNH-tetrazolium reductase activity in Nissl substance. The possible functional significance of these localizations is briefly discussed, as is their relation to "quantitative histochemistry" data available in the literature.

Acid Phosphatase↗
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↗
PubMed1958

Adenosinetriphosphatase activity in the cell membranes of kidney tubule cells.

This cytochemical study demonstrates high levels of apparent ATPase activity in the infolded cell membranes of the proximal tubules (dog, rat, human, mouse, monkey, and opossum) and ascending loops of Henle (dog, rat, human and, to a variable degree, mouse). Electron microscopy has shown (see Rhodin (1)) that these membranes separate adjacent cells where they interlock with one another by multiple cytoplasmic lamellae containing oriented mitochondria. The significance of the high ATPase activity is considered in relation to possible movements of the membranes and to "active transport" believed to occur there. In the rat, enzyme activity in the proximal tubule membranes does not survive formol-calcium fixation, and it is therefore necessary to use unfixed sections for its demonstration. However, in edematous rats with experimental nephrosis (induced by the injection of aminonucleoside or with antikidney serum) marked ATPase activity is exhibited in these membranes even after formol-calcium fixation. When proximal tubule or Henle loop cells of the dog acquire an altered metabolism, as indicated by accumulated lipide spheres or by "droplets," the infolded ATPase-rich membranes are no longer demonstrable.

Adenosine Triphosphatases↗
PubMed1956

Electron microscopy: cytology of cell fractions.

It should be evident from this brief account that electron microscopy of thin sections is an invaluable asset in the study of fractions isolated by differential centrifugation. I have tried to indicate how the integrity of particles, purity of fractions, and the existence of new particles can be established through its use. I have also suggested the desirability of a common terminology for all cytology -classic, electron-microscopic, and biochemical. Some have expressed the opinion that neutral terms such as alpha, beta, and gamma membranes (59) are more useful than ergastoplasm, Golgi apparatus, and so forth. As helpful as such neutral terms may be in describing intracellular structures, they do not appear to me to substitute for historically rooted cytological names. Note added in proof: Since this article went to press there has appeared an important article by G. E. Palade and P. Siekevitz (60). These authors consider that the vesicles without granules found in the microsome fraction were "probably derived from the smooth surfaced parts of the endoplasmic reticulum." The latter were found to be continuous with the granule-studded membranes; "the two varieties of profiles represent local differentiation within a common system." The authors confirm the finding of Rouiller (18) and Novikoff et al. (7) of the dense bodies adjacent to the bile canaliculi and describe their presence in the microsome fraction as a "minor component."

Animals↗
PubMed1956

Electron microscopy of lysosomerich fractions from rat liver.

A preliminary electron microscope study has revealed the presence in lysosome-rich fractions, isolated from rat liver, of hitherto undescribed cytoplasmic particles, called "dense bodies." Approximately 0.37 micro in length, the dense bodies often possess an internal cavity and external membrane. They contain many electron-dense granules 55 to 77 A, or less, in diameter. Such dense bodies are also visible in electron micrographs of parenchymatous cells in liver sections. The correlations between dense bodies and lysosomes are listed, but until pure preparations are available it is not possible to assert that dense bodies and lysosomes are identical.

Animals↗