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Biomedical subjects

S Fowler

Publications and source records attributed to S Fowler.

At least 109 records · Page 6Linked to original sources
PubMed1977

Polychlorinated biphenyls: penetration into the deep ocean by zooplankton fecal pellet transport.

High concentrations of polychlorinated biphenyls (PCB's) were found in fecal pellets from natural populations of euphausiids collected in the Ligurian Sea. Since biogenic particulate products, especially fecal pellets, are known to sink rapidly and intact to the ocean bottom, the transport of PCB's by such sinking particles could be an important mechanism which contributes to the penetration of PCB's into the deep sea.

Animals↗
PubMed1977

Subcellular fractionation and morphology of calf aortic smooth muscle cells. Studies on whole aorta, aortic explants, and subcultures grown under different conditions.

A comparative biochemical and morphological study was made of calf aortic smooth muscle cells found in situ and grown in vitro under various conditions. Striking alterations in enzyme contents, physical properties, and morphological appearances of lysosomes, endoplasmic reticulum, plasma membranes and, to a lesser extent, mitochondria were observed upon culturing of calf aortic smooth muscle cells. These changes first appeared in cells growing out of tissue explants. They developed further upon subculturing of the cells and depended greatly on the culture conditions used. The alterations included increases in specific activities of some 5- to 25-fold of four acid hydrolases, an average ninefold increase in 5' -nucleotidase, sevenfold increase in cytochrome oxidase, and fourfold increase in neutral alpha-glucosidase in subcultured smooth muscle cells compared to aortic cells in situ. Cell fractionation studies showed significant shifts in the equilibrium densities of plasma membranes, microsomes, and lysosomes, but not of mitochondria, in smooth muscle cells growing out from explants and in subcultured cells, compared to cells isolated from intact aortas. Although the cells grown in vitro exhibited typical phenotypic features of smooth muscle cells such as abundant myofilaments and surface vesicles, alterations in the morphological appearance of the endoplasmic reticulum, Golgi apparatus, and, especially, lysosomes were observed. These results demonstrate significant differences in specific cellular characteristics and functions of aortic smooth muscle cells grown in vitro compared to aortic cells in situ.

Aorta↗
PubMed1977

Characterization of lipid-laden aortic cells from cholesterol-fed rabbits. I. Resolution of aortic cell populations by metrizamide density gradient centrifugation.

Enzymatically isolated aortic cells from control and cholesterol-fed rabbits were subjected to isopycnic density gradient centrifugation in Metrizamide. Control cells formed a single band equilibrating at a median density of 1.13 to 1.14, while cells isolated from atheromatous aortas formed two distinct bands, one equilibrating in the density range of 1.12 to 1.14 and the other occurring at a lower density of 1.03 to 1.07. Morphologically, the low density cells exhibited typical features of aortic foam cells. They were found to be greatly enriched in free and esterified cholesterol and in four lysosomal hydrolases. Further studies showed these cells to contain lipid-laden lysosomes. The high density cells from cholesterol-fed rabbits were also enriched in cholesterol and lysosomal enzymes compared to control aortic cells but not to the extent showen by the low density foam cells. While exhibiting the ultrastructural characteristics of smooth muscle cells, the cells in this fraction showed a considerable degree of morphologic and biochemical heterogeneity, suggesting the occurrence of many transition forms between normal smooth muscle cells and fully transformed foam cells.

Animals↗
PubMed1976

Analytical study of microsomes and isolated subcellular membranes from rat liver. V. Immunological localization of cytochrome b5 by electron microscopy: methodology and application to various subcellular fractions.

The localization of cytochrome b5 on the membranes of various subcellular organelles of rat liver was studied by a cytoimmunological procedure using anti-cytochrome b5/anti-ferritin hybrid antibodies and ferritin as label. For this study, highly purified and biochemically characterized membrane preparations were employed. Outer mitochondrial membranes were found to be heavily labeled by the hybrid antibodies whereas Golgi and plasma membranes were not marked by the reagent. Peroxisome membranes were moderately labeled by the hybrid antibodies, suggesting that they may contain some cytochrome b5. The preparation and purification of hybrid antibodies without peptic digestion is described and an analysis made of the composition of the final reagent product.

Animals↗
PubMed1976

Analytical study of microsomes and isolated subcellular membranes from rat liver. VI. Electron microscope examination of microsomes for cytochrome b5 by means of a ferritin-labeled antibody.

The distribution of cytochrome b5 in rat liver microsomes, and in two microsomal subfractions isolated by density equilibration in a linear sucrose gradient, was studied under the electron microscope by means of a ferritin-labeled hybrid anti-cytochrome b5/anti-ferritin antibody. Results of this study show that cytochrome b5 is present in essentially all microsomal vesicles derived from endoplasmic reticulum (ER), whether rough or smooth. Thus, the dissociation of ER constituents into two groups (b and c), achieved by subfractionating microsomes by isopycnic centrifugation (Beaufay, H., A. Amar-Costesec, D. Thines-Sempoux, M. Wibo, M. Robbi, and J. Berthet. 1974. J. Cell Biol. 61:213-231), does not reflect the association of each group with distinct microsomal particles but reflects rather an enzymatic heterogeneity of the ER: the ratio of group c to group b enzymes increasing with the density and ribosome load of the particles.

Animals↗
PubMed1968

The large-scale separation of peroxisomes, mitochondria, and lysosomes from the livers of rats injected with triton WR-1339. Improved isolation procedures, automated analysis, biochemical and morphological properties of fractions.

Improved, largely automated methods are described for the purification and analysis o peroxisomes, lysosomes, and mitochondria from the livers of rats injected with Triton WR-1339. With these new methods, it has become possible to obtain, in less than 6 hr and with reliable reproducibility, mitochondria practically free of contaminants, as well as the rarer cytoplasmic particles in amounts (about 100 mg of protein) and in a state of purity (95%) that make them suitable for detailed biochemical studies. The results obtained so far on these preparations have made more conclusive and precise previous estimates of the biochemical and morphological properties of the three groups of cytoplasmic particles. In addition, peroxisomes were found to contain essentially all the L-alpha-hydroxy acid oxidase of the liver, as well as a small, but significant fraction of its NADP-linked isocitrate dehydrogenase activity. Another small fraction of the latter enzyme is present in the mitochondria, the remainder being associated with the cell sap. The mitochondrial localization of the metabolically active cytoplasmic DNA could be verified. The relative content of the fractions in mitochondria, whole peroxisomes, peroxisome cores, lysosomes, and endoplasmic reticulum was estimated independently by direct measurements on electron micrographs, and by linear programming (based on the assumption that the particles are biochemically homogeneous) of the results of enzyme assays. The two types of estimates agreed very well, except for one fraction in which low cytochrome oxidase activity was associated with mitochondrial damage.

Acid Phosphatase↗
PubMedDate not supplied

When consultants and clients clash.

This fictitious case study explores the issues that surround the relationships between consultants and their clients, as well as the dynamics of a newly merged organization. Susan Barlow, a senior consultant with the Statler Group, dreaded her upcoming status meeting. She had thought it a lucky break when she got assigned to the Kellogg-Champion project. Royce Kellogg, the CEO of the newly merged firm, had engaged the Statler Group for what seemed a simple project: to reconcile the policies and practices of the two former firms now that they had become one. But once on the job, Barlow realized that the issues were much more complex than they had seemed. The new firm needed help badly-but not the kind of help that the client had led Barlow to believe it needed. What would she and Jim Roussos, her partner on the assignment, tell Kellogg at the meeting? Kellogg, for his part, was not looking forward to the status meeting, either. From his point of view, the consultants had caused more problems than they had solved. What's more, he wasn't even dealing with the consultants he had hired. Where was George Gray, the senior partner he had met with originally? Maybe Barlow and Roussos were just too young and inexperienced. Kellogg felt he was getting a raw deal. How would he approach them in the morning? Should he fire them or make an attempt at damage control? Two experts advise the consultants and two advise the client on how to handle the status meeting.

Consultants↗