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Biomedical subjects

M M Friedman

Publications and source records attributed to M M Friedman.

At least 73 records · Page 4Linked to original sources
PubMed1984

Organelle-depleted human neutrophil cytoplasts used to study fmet-leu-phe receptor modulation and cell function.

Organelle-depleted human neutrophil cytoplasts were used to study N-formylmethionylleucylphenylalanine (fmet-leu-phe) receptor regulation and adaptation, aggregation, chemotaxis, and chemoattractant-elicited changes in shape, volume, and surface charge. Cytoplasts aggregated in response to the chemoattractant fmet-leu-phe, but the magnitude of the response was less than that in neutrophils. Unlike neutrophils, cytoplasts did not exhibit a second wave of aggregation with the addition of cytochalasin B and also failed to disaggregate. In chemotactic assays, cytoplasts migrated poorly into cellulose nitrate filters, and compared with intact neutrophils required a 100-fold greater concentration of fmet-leu-phe to elicit shape change. In contrast to neutrophils, cytoplasts did not decrease their surface charge in response to fmet-leu-phe and did not exhibit an increase in the binding of fmet-leu-[3H]phe after stimulation with phorbol myristate acetate. However, receptor adaptation and induced changes in membrane potential, as measured by using the membrane probe di-O-C5(3), were similar in cytoplasts and in neutrophils. The data suggest that the presence of functional intracellular organelles is required for normal aggregation and disaggregation, chemotaxis, and shape change induced by fmet-leu-phe, and also peptide receptor upregulation in response to secretagogues. The data show that peptide receptor adaptation occurs in the absence of secretory granules and is independent of receptor upregulation .

Carbocyanines↗
PubMed1983

Ultrastructural, biochemical, and functional characteristics of histamine-containing cells cloned from mouse bone marrow: tentative identification as mucosal mast cells.

Two histamine-containing granulated cell lines were cloned from mouse bone marrow by using sequential soft agar and limiting dilution techniques. Concanavalin A-stimulated mouse spleen cell supernatants were required for cell proliferation. Cloned cell lines were Lyt-1.2, Lyt-2.2, Thy-1.2, surface Ig negative, I-A positive, and failed to ingest latex particles. Cells expressed 6.4 to 9.0 X 10(4) IgE high affinity receptors and contained approximately 1 to 2 pg of histamine per cell. Electron microscopy revealed granule and surface membrane features characteristic of mast cells. The cloned histamine-containing granulated cell lines synthesized a proteoglycan containing glycosaminoglycan side chains with an estimated average m.w. of 40,000. The glycosaminoglycan side chains consisted only of chondroitin sulfates identified by charge characteristics and through the use of selective polysaccharidases. These cells degranulated to immunologic stimuli and the calcium ionophore A23187 but not to compound 48/80. Taken together, the above findings suggest that these histamine-containing granulated cell lines that are cloned from bone marrow are mucosal (atypical) mast cells.

Animals↗
PubMed1983

Phagocytosis of mast cell granules by cultured fibroblasts.

Cultured rat embryonic skin fibroblasts phagocytosed rat mast cell granules added to the medium or released from co-cultured mast cells by rabbit anti-rat IgE or Compound 48/80. Electron microscopy of fibroblasts incubated with mast cell granules revealed that granules adjacent to the plasmalemma were engulfed by long, thin cytoplasmic processes. Internalization proceeded to fusion of encircling processes and formation of phagosomes. Microtubules and 60 A microfilaments became closely associated with the phagosomal membrane to which small vesicles and cisternae of endoplasmic reticulum fused. The rate of uptake of mast cell granules by fibroblasts was dependent upon temperature and granule concentration. Cytochalasin B inhibited granule uptake whereas colchicine and nocodazole had little effect. Phagocytosis was not influenced by actinomycin D and cycloheximide, was partially inhibited by fluoride, and was markedly inhibited by cyanide, azide, and 2,4-dinitrophenol. Supernatants from fibroblast cultures incubated with mast cell granules for 24 and 48 hr, during which period phagocytosis occurred, contained elevated levels of collagenase and beta-hexosaminidase, but normal levels of lactate dehydrogenase and superoxide dismutase. These results support the concept that immediate hypersensitivity reactions are in part terminated by phagocytosis of biologically active discharged mast cell granules by resident connective tissue fibroblasts. Further, it is suggested that a consequence of this process is an alteration in fibroblast behavior, providing a unique link between immediate hypersensitivity reactions and connective tissue responses to inflammation.

Animals↗
PubMed1982

Effects of taxol on human neutrophils.

Taxol, a plant alkaloid, promotes and stabilizes microtubule assembly in cells and cellfree systems. In the present study, the effects of taxol on various functional, morphologic, and biochemical phenomena in human peripheral blood PMN (Hypaque-Ficoll) were examined. Taxol (10(-7) M) inhibited PMN chemotaxis stimulated by N-formyl-methionyl-leucyl-phenylalanine (f-met-leu-phe) or endotoxin-activated serum by more than 60%. The inhibition was not readily reversed by washing, and taxol itself was not a chemoattractant, nor is it a secretagogue. Spontaneous nondirected migration, cell spreading on a glass surface, and orientation of cell organelles in response to a chemoattractant gradient were also inhibited by taxol. Taxol (10(-5) M) decreased killing of Staphylococcus aureus, but did not alter phagocytosis of heat-killed Candida or hexose monophosphate shunt activity in resting or stimulated PMN. Ultrastructural studies showed that PMN incubated in f-met-leu-phe, taxol, or both had increased (p less than 0.001) numbers of centrosome-associated microtubules, and the microtubules of cells incubated in taxol with or without f-met-leu-phe were organized into bundles. Taxol (10(-5) M) markedly inhibited post-translational tyrosinolation of alpha-chains of tubulin in both resting and f-met-leu-phe-stimulated PMN. The data indicate that taxol inhibits PMN locomotion and bacterial killing, supporting a role for microtubules in these processes. The ultrastructural and biochemical data also support the view that taxol mediates its effects on PMN by its effect on microtubules.

Alkaloids↗
PubMed1975

Chemoreceptors and feeding in calanoid copepods (Arthropoda: Crustacea).

Ultrastructural studies of the mouthparts of the calanoid copepod Diaptomus pallidus have revealed the presence of numerous chemoreceptors, and the apparent absence of mechanoreceptors. The setae contain no muscles, and the setules are noncellular extensions of their chitin wall. This allows a new insight into the selective feeding of zooplankters.

Animals↗
PubMed1971

Dr. N.H. Myers.

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History, 20th Century↗