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Biomedical subjects

S L Gartner

Publications and source records attributed to S L Gartner.

12 recordsLinked to original sources
PubMed1993

Complement activation during saturation diving.

In this study, the levels of activated complement fragments C3a and C5a were measured on 11 U.S. Navy divers as they performed a 28-day saturation dive to a pressure equivalent of 1,000 feet of seawater (fsw, 31.3 atm abs). Two subjects developed symptoms consistent with the high pressure nervous syndrome (HPNS) and three were treated for type I DCS (joint pain only). These events allowed us to test two hypotheses: a) alterations in C3a or C5a levels during compression are related to the occurrence of HPNS and b) increases in complement fragments are an indicator of decompression stress associated with type I DCS. There was no correlation between changes in C3a and C5a levels during compression and the diagnosis of HPNS. Our results suggest that an increase in C3a and C5a levels during saturation diving correlates with decompression stress and the clinical diagnosis of type I DCS.

Analysis of Variance↗
PubMed1992

Modulation of interleukin-1 induced thymocyte proliferation by D-mannose.

We examined the effect of various carbohydrates on the proliferative response of murine thymocytes to cytokines. The monosaccharide, D-mannose (4-10 mM), significantly inhibited thymocyte proliferation induced by recombinant interleukin-1 (rIL-1). Mannose also inhibited the proliferation response to native, human IL-1. Inhibition was specific for D-mannose and methyl-alpha-D-mannopyranoside. Other carbohydrates, including L-mannose and D-glucose did not inhibit thymocyte growth. Thymocyte proliferation induced by either IL-2 or pokeweed mitogen was also inhibited by mannose. Mannose was effective in inhibiting T-cell proliferation even when added 48 hours after the start of the experiment. Mannose did not appear to be toxic to the thymocytes as judged by trypan blue exclusion. These data are consistent with the hypothesis that specific carbohydrates may alter immune function. Manipulation of immune function via blocking cytokine activity may be useful in certain pathological conditions.

Animals↗
PubMed1989

Phospholipase C activity in human polymorphonuclear leukocytes: partial characterization and effect of indomethacin.

Several hormones act at the cellular level to increase diacylglycerol via increased catabolism of phosphatidylinositol by phospholipase C. Diacylglycerol stimulates protein kinase C, leading to protein phosphorylation and hormone action. Since phospholipase C activity has not been well studied in man, we have established an assay for phospholipase C in human neutrophils. In this assay sonicates of neutrophils were incubated with L-3-phosphatidyl-[U 14C]-inositol and the incubation mixture extracted with chloroform/methanol. Following the additions of 2 mol/l KCl and chloroform, phospholipase C activity was determined by counting [14C] in the aqueous phase. The phospholipase C activity was linear with respect to time and the quantity of added enzyme. Optimum substrate concentration and pH were 2 mmol/l and 7.0, respectively. Optimal activity was dependent on Ca2+ (2 mmol/l) and deoxycholate (2 mmol/l). Naloxone, and PGD2, which affect various aspects of leucocyte function, had no significant effects on neutrophil PLC activity. The effects of various compounds with phospholipase A2 inhibitory activity were also tested on this enzyme. Of these, mepacrine, lidocaine and indomethacin inhibited the enzyme activity. The inhibition by indomethacin was of the noncompetitive type with an apparent Km of 0.17 X 10(-6) mol/l and apparent Ki of 3.6 X 10(-6) mol/l. From these data we conclude that indomethacin is capable of inhibiting phospholipase C activity in neutrophils at clinically significant levels and that this may be relevant in the therapeutic action of this drug.

Calcium↗
PubMed1988

Effects of lipopolysaccharide, lipid A, lipid X, and phorbol ester on cultured bovine endothelial cells.

In pursuing the mechanism of endotoxin action, we examined the effect of lipopolysaccharide (LPS) and its chemically defined components, lipid A and lipid X on cultured bovine endothelial cells. We report that LPS and lipid A caused detachment and altered morphology of endothelial cells while lipid X did not. Phorbol myristate acetate, a compound known to activate protein kinase C, also caused endothelial cell detachment. Morphologic changes were readily apparent in the endothelial cells after 6 hours of exposure to lipopolysaccharide (1 microgram/ml); at that time many of the cells had contracted and formed bleblike structures on the surface. Large vacuoles, dense bodies, and pyknotic nuclei were found in the detaching cells, indicating necrosis or cell death. Preceding the morphologic changes and actual detachment, endothelial cell DNA and RNA synthesis was impaired by LPS. The changes in DNA and RNA synthesis occurred within 4 hours of exposure to 1 microgram/ml of LPS when the cells were still able to maintain normal levels of ATP. In addition to the inhibition of nucleic acid synthesis, protein synthesis was inhibited after 6 and 8 hours of LPS exposure. DNA, RNA, and protein synthesis returned to control levels after 24 hours of exposure. Investigation on the cultured bovine endothelial cells as a model for LPS action was useful in that these cells are sensitive to relatively low levels of LPS and the endothelium may be an important target in sepsis.

Animals↗
PubMed1985

Enhanced phospholipase A2 activity in rat plasma, liver, and intestinal mucosa following endotoxin treatment: a possible explanation for the protective effect of indomethacin in endotoxic shock.

Endotoxin administration in rats produced a significant increase in plasma, hepatic, and intestinal phospholipase A2 activity within three minutes after injection. The elevated phospholipase A2 activity seen in these tissues returned to normal levels six minutes after injection. The changes in phospholipase A2 activity were dose-dependent within the 0, 10, and 20 mg/kg range of treatment with Escherichia coli endotoxin. This increase in plasma, hepatic, and intestinal phospholipase A2 was abolished by prior treatment of the rats with 3 mg/kg indomethacin, a drug known to improve survival in endotoxic shock. The fact that the change in phospholipase A2 occurs soon after endotoxin administration and that the change in phospholipase is blocked by protective doses of indomethacin suggests that phospholipase A2 activation may be an important initial event in the lethal action of endotoxin, and that the protective effects of indomethacin may be directly related to inhibition of phospholipase A2 activity. Further, in vitro studies of the effects of indomethacin on hepatic phospholipase A2 activity showed that indomethacin significantly inhibited this enzyme. Indomethacin (25 mumol/L) produced 56% inhibition in phospholipase A2 activity and the apparent Ki for indomethacin was 9.2 mumol/L. Kinetic analysis using the Lineweaver-Burk method showed that the indomethacin inhibition was of the noncompetitive type.

Animals↗
PubMed1977

Lead potentiation of endotoxin lethality in rats: lack of effect of kininase inhibition.

Although lead and SQ20881 are potent in vitro inhibitors of kininase II activity, SQ20881 does not alter the sensitivity of rats to endotoxin. These results indicate that marked changes in plasma kininase activity do not contribute to endotoxin morbidity and that kininase inhibition is not the mechanism whereby lead ions sensitize rats to endotoxin.

Angiotensin-Converting Enzyme Inhibitors↗