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Biomedical subjects

M L Karnovsky

Publications and source records attributed to M L Karnovsky.

At least 145 records · Page 8Linked to original sources
PubMed1969

Measurement of rates of phagocytosis: the use of cellular monolayers.

A method has been developed for measuring the rate of phagocytosis rather than the quantity of particles ingested per cell when the process is virtually complete. The method, which is simpler and more rapid than those described previously, utilizes cellular monolayers, radioactive particles, and short incubation times. Under the conditions described, the rate of uptake of particles by either guinea-pig peritoneal or human blood leukocytes was proportional to both cell concentration and the time of incubation, and was independent of changes in the concentration of particles during the measurement. The particles were retained by the cells for at least 90 min. The most suitable particles so far used have been (32)P-labeled Salmonella typhimurium, and acetyl-(14)C- or methyl-(14)C-labeled starch particles. The oxidation of (14)C-labeled glucose has been studied under the same conditions that were used for the assays of phagocytosis: the greatest increase in formation of (14)CO(2) from glucose-1-(14)C occurred a few minutes after the most rapid period of phagocytosis.

Animals↗
PubMed1969

Degranulation of leukocytes in chronic granulomatous disease.

Quantitative chemical analyses of the subcellular distribution patterns for acid and alkaline phosphatase, beta glucuronidase and peroxidase were obtained for human peripheral blood leukocytes of four patients with chronic granulomatous disease (CGD). Five young adults with acute infections served as controls. The observations were made on fractions obtained by homogenization and centrifugation of leukocytes previously incubated with or without particles for ingestion. Distributions in resting CGD and normal cells were very similar for acid and alkaline phosphatase and peroxidase, but the proportion of beta glucuronidase in the granule fraction of CGD cells was depressed, with an increased proportion in the soluble fraction. Release of granule-bound enzymes during phagocytosis of a variety of particles was the same for CGD and control cells, except that release of beta glucuronidase was less marked in CGD cells. Total enzymatic activity of CGD cells for the hydrolases studied was normal. The data indicated that granular enzymes are released in a normal fashion in phagocytizing CGD cells. Supportive evidence of release of enzymes into the phagocytic vacuole of CGD cells was obtained by an electron microscopic study of myeloperoxidase.

Acid Phosphatase↗
PubMed1968

Deficiency of reduced nicotinamide-adenine dinucleotide oxidase in chronic granulomatous disease.

Reduced nicotinamide-adenine dinucleotide oxidase of normal human polymorphonuclear leukocytes has properties that would qualify it as the enzyme responsible for the respiratory burst during phagocytosis. The enzyme was deficient in leukocytes of five patients with chronic granulomatous disease. This lack of adequate reduced nicotinamide-adenine dinucleotide oxidase could be the basis for the metabolic abnormalities characteristic of these leukocytes and for their diminished bactericidal activity.

Blood Bactericidal Activity↗
PubMed1968

Stages in the incorporation of fatty acids into red blood cells.

Mature human erythrocytes were incubated with (14)C-labeled palmitic acid bound to crystalline human albumin. Energy-dependent incorporation of the labeled palmitic acid into cell membrane phospholipids occurred, and various stages in this incorporation were defined. Initially the palmitic acid was rapidy transferred from the albumin to a "superficial" membrane pool of free fatty acid (F-1), which was removable when the cells were washed with defatted albumin. This process was independent of red cell metabolism. The labeled fatty acid then passed into a second "deeper" membrane pool of free fatty acids (F-2), which was not extractable with albumin. This process was energy-dependent and proceeded at a slower rate than the initial transfer from albumin to F-1. Ultimately the labeled fatty acid was incorporated into phosphatides (PL). This process also was dependent upon cellular metabolism. The kinetics of pulse label studies suggest that the processes observed were sequential and that precursor-product relationships exist between the F-1 and F-2 pools and the F-2 and PL pools. [Formula: see text] From the size and specific activities of these pools, calculations of the extent of phospholipid turnover were made. An approximate figure of 2% /hr or 30 nmoles/ml of packed red blood cells per hr was obtained. The figure was further calculated to represent an energy cost to the red blood cell of approximately 5% of the energy available from glycolysis.

Cell Membrane Permeability↗
PubMed1967

Sleep: effects on incorporation of inorganic phosphate into brain fractions.

During sleep there is a two- to threefold increase in the incorporation of inorganic orthophosphate-(32)P into a chemical fraction of the brain of the 20-day-old rat. This increase is not in the lipids or nucleic acids, but is associated with an acid-labile phosphate entity of the tissue residue after extraction of these fractions and phosphorus-containing substances of low molecular weight.

Animals↗
PubMed1967

Metabolic and morphological observations on the effect of surface-active agents of leukocytes.

Morphological and metabolic observations have been made on the effects of endotoxin, deoxycholate, and digitonin (at less than 50 microg/ml) on polymorphonuclear leukocytes and mononuclear cells. The agents stimulate the respiration and glucose oxidation of these cells in a manner similar to that seen during phagocytosis. Electron microscopy revealed no morphological changes with the first two agents, but dramatic membrane changes were seen in the case of digitonin. Here tubular projections of characteristic size and shape formed on and split off the membrane. All the agents stimulated uptake of inulin, but efforts to demonstrate increased pinocytosis by electron microscopy have not so far succeeded, probably due to limitations in present experimental techniques.

Animals↗
PubMed1967

Concomitant alterations of sodium flux and membrane phospholipid metabolism in red blood cells: studies in hereditary spherocytosis.

The role of membrane phosphatides in transport processes has been investigated in red cells from splenectomized patients with hereditary spherocytosis (HS). Incorporation of inorganic (32)phosphate into the membrane phosphatides of HS red cells was approximately twice normal, coinciding with the nearly twofold increment in flux of sodium ions in the cells.A consistent, inordinate increase in specific activity of a chromatographic fraction containing phosphatidylserine provided the bulk of the over-all increase in labeling of HS red cell phosphatides. The specific activity of phosphatidic acid was increased but not consistently. Radioactivity of the "acidic phosphatides" (phosphatidylserine and phosphatidic acid fractions) decreased, in general, when the sodium flux was low, i.e., when the cells were suspended in media of low sodium content. When the cation flux was elevated (hypotonic media), there was a marked (ca. 35%) increase in the labeling of phosphatidylserine fractions. Normal red cells whose permeability to cations was increased by exposure to 0.5 N butanol also exhibited increased labeling of acidic phosphatides. Considerations of the stoichiometry of cation transport and phosphatide labeling make it unlikely that phospholipids act directly as carrier molecules for cations in red cell membranes. On the other hand, the involvement of these lipid substances in cation movements is substantiated by correlating several different states of sodium flux with the labeling of the phosphatidic acid and phosphatidylserine fractions.

Biological Transport↗