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Biomedical subjects

S W Green

Publications and source records attributed to S W Green.

28 records · Page 2Linked to original sources
PubMed1987

Exposure to gamma-irradiation increases phorbol myristate acetate-induced H2O2 production in human macrophages.

Cell number, protein, and phorbol myristate acetate (PMA)-induced H2O2 production were measured in cultured human peripheral blood monocytes for six days after exposure to varying doses of gamma-radiation. Both the number of adherent cells and the protein per dish decreased with increasing radiation doses. The dose of radiation decreasing the number of adherent cells by 37% on days 4 and 6 postirradiation was 29 Gy. Four hours postirradiation there was a small decrease in PMA-induced H2O2 production for doses of 7.5 Gy or greater; levels returned to normal by eight hours and increased at 24 hours postirradiation. By day 4 postirradiation significant increases in PMA-induced H2O2 production were noted at all radiation doses (2.5 to 50 Gy). This increase was not due to a shift in the PMA dose-response curve, a change in the time course of the PMA response, or an effect of decreased cell density on the assay system. Superoxide levels were not significantly changed in cells exposed to 20 Gy. Catalase, glutathione peroxidase, and superoxide dismutase levels also were unchanged. Culturing irradiated cells with gamma-interferon increased PMA-induced H2O2 release, which indicated that irradiated cells retained their capacity to respond to gamma-interferon. These data demonstrate that irradiation affects the PMA-induced H2O2 production of human monocytes in a time- and dose-dependent manner. An increase in the release of reactive oxygen intermediates by the macrophage may play a role in enhancing the deleterious effects of radiation in vivo.

Azides↗
PubMed1985

Enhanced activity of the macrophage-like cell line J774.1 following exposure to gamma radiation.

Exposure of the macrophage-like cell line J774.1 to 20 gray of cobalt-60 gamma radiation resulted in a block of tritiated thymidine incorporation, along with an increase in cell "activation," as assessed by increases in lysosomal enzyme and ectoenzyme content, PMA-induced H2O2 production, and NBT staining, ingestion of E(IgG), spreading, and membrane ruffling. These changes are evident within 1 day postradiation and peak at 4 days postradiation.

Animals↗
PubMed1984

Defective Fc-mediated phagocytosis in gamma-irradiated mouse peritoneal macrophages.

Ingestion of bovine red blood cells opsonized with IgG, by irradiated and control cultures of mouse peritoneal macrophages, was monitored at various times following exposure to 7.5-20 Gy of 60Co. Radiation produced decreases in the percentage of phagocytic cells and reduced the phagocytic index of the macrophages at 6-10 days post-irradiation. Only a small decrease in the phagocytic index of irradiated cultures was noted on day 3 post-irradiation. Cell survival as monitored by cell number and lactic dehydrogenase release as well as the levels of beta-glucuronidase and lysozyme were less sensitive to radiation exposure than was the phagocytic ability of the cultures. Addition of 8-bromo-3',5'-cyclic adenosine monophosphate and prostaglandin E2 to cultures increased the phagocytic ability of both irradiated and control cultures but did not abolish the deficit produced by radiation. The data indicate that in vitro radiation exposure produces time-dependent changes in the ability of mouse peritoneal cells to ingest IgG coated red blood cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1984

Ovarian steroid metabolism and oestrogens in the corpus luteum of the tammar wallaby.

Ovaries were obtained from tammar wallabies at various stages of the reproductive cycle to examine the occurrence of oestrogens in corpora lutea, and the synthesis and metabolism of steroids in the corpus luteum and ovarian cortical and interstitial tissues. Corpora lutea contained oestradiol-17 beta and oestrone during embryonic diapause and at all stages of pregnancy studied after blastocyst activation. Aryl sulphatase, 3 beta-hydroxysteroid dehydrogenase and 17 beta-oxidoreductase were shown to be present in luteal and other ovarian tissues by incubation in vitro with labelled substrates. Aromatase was undetectable in corpora lutea or in interstitial tissue, but was present in the ovarian tissues (including follicles) which remained after removal of corpora lutea. The probable source of the oestrogens detected in the corpus luteum is discussed in relation to their role in the inhibition of follicular development during embyronic diapause.

Androstenedione↗
PubMed1982

Changes in the milk proteins during lactation in the tammar wallaby, Macropus eugenii.

Samples of whey proteins from the milk of tammar wallabies, Macropus eugenii, were examined by acrylamide gel electrophoresis at all stages of lactation up to 280 days post partum. Whey albumin, beta-globulin and gamma-globulin fractions had similar electrophoretic mobility to that of the equivalent serum protein fractions, but the proteins in the alpha-globulin and pre-albumin regions differed markedly. The alpha-globulins are presumed polymorphic because individuals at the same stage of lactation showed great variability in these electrophoretic regions: up to five polymorphic bands were recognized. Milk proteins changed qualitatively throughout lactation, and in particular the concentration of the pre-albumin and alpha-globulin fractions increased from approximately day 180 to the end of lactation. Total protein concentration of both whole milk and whey approximately doubled in the second half of lactation compared to the first half, reaching maximum mean values of 114 +/- 47 and 96 +/- 50 gl-1, respectively. Whole milk contained consistently more protein than whey, presumably due to the casein it contains.

Aging↗
PubMed1982

Ontogeny of the brain in a marsupial (Macropus eugenii) throughout pouch life. I. Brain growth.

Growth characteristics of the tammar wallaby brain have been determined from 143 animals at various stages of growth from birth to adulthood, with particular emphasis on the 250 days of pouch life. The macroscopic anatomy of the brain is also described for pouch young at days 3, 5, 88 and 190 days after birth, and for the adult. The transition from the rapid to mature growth phases of each brain structure occurs between days 120 and 180 after birth, and coincides with the appearance of previously described developmental characters or behaviour. The allometric relationships of brain and body growth described in this marsupial resemble those described for primates. Because of the accessibility of the pouch young during the critical period of brain differentiation, this marsupial may provide a useful laboratory model for the study of brain development.

Aging↗
PubMed1981

Aldosterone stimulates Na+ transport without affecting citrate synthase activity in cultured cells.

Aldosterone increases citrate synthase activity in toad urinary bladder and mammalian kidney. It has been suggested that this action is important to aldosterone stimulation of Na+ transport, and it has been used as a marker of those epithelia which are stimulated by aldosterone. We describe three continuous lines of cultured cells derived from toad urinary bladder and toad kidney in which aldosterone increases active Na+ transport but does not increase the activity of citrate synthase. Therefore, in cultured cells at least, citrate synthase is not a critical enzyme for, or a suitable marker of, aldosterone stimulation of Na+ transport.

Aldosterone↗
PubMed1981

Epithelial organization and hormone sensitivity of toad urinary bladder cells in culture.

Two continuous cell lines (TB-M and TB-6c) derived from epithelial cells of the toad urinary bladder form epithelia in culture that manifest hormone-sensitive transepithelial transport. Development of transepithelial electrical resistance (R) and transport rate (ISC) are dependent on time and density of cells seeded, but steady-state ISC and R are characteristic for each cell line and independent of seeding density. Some responses of intact toad bladder are preserved in culture, whereas others are altered or absent. Neither cell line responds to vasopressin. Analogues of cAMP increase sodium transport and urea permeability in both cell lines but do not affect water permeability. The intramembrane particle aggregates associated with the vasopressin- and cAMP-induced increase in water permeability of the intact bladder could not be detected in the cell lines. Aldosterone increases sodium transport in both cell lines, and the time course and concentration dependence of the response to aldosterone are similar to those of the intact bladder. The relative effect of a series of steroids on ISC reveals corticosterone to be a more potent mineralocorticoid in cultured cells than in the intact bladder.

Animals↗
PubMed1979

Growth of the corpus luteum and its progesterone content during pregnancy in the tammar wallaby, Macropus eugenii.

Corpora lutea were obtained from wallabies at different stages of pregnancy, following removal of pouch young to initiate embryonic development. Progesterone was present at a concentration of 11.3 ng/mg in quiescent corpora lutea from lactating animals. Progesterone values rose with increasing corpus luteum weight to reach a maximum of 40--50 ng/mg in corpora lutea weighing 50--60 mg. Total progesterone reached a maximum of 1500 +/- 300 (s.e.m.) ng at Days 21--23 after removal of pouch young, but fell markedly at Days 24 and 25 (900 +/- 150 ng) immediately before parturition.

Animals↗