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S L Snyder

Publications and source records attributed to S L Snyder.

At least 37 records · Page 2Linked to original sources
PubMed1987

Quantification of gut injury with diamine oxidase activity: development of a fission neutron RBE and measurements with combined injury in mouse models.

Plasma and small intestine diamine oxidase (DAO) activities were measured on Days 2, 4, and 6 following irradiation of mice with a range of doses of fission neutrons and 60Co. With increasing doses of radiation, plasma DAO activity increased on Day 2 and intestinal DAO activity decreased on Day 4; moreover, the approximate relative biological effectiveness values for these changes in activity were 5.81 for plasma DAO activity on Day 2 and 3.88 for intestinal DAO activity on Day 4. On Day 6 relatively high levels of radiation caused DAO activity in the small intestine to remain depressed whereas low levels resulted in recovery with activities at or near controls. In animals with combined injury (radiation plus 30% surface burn or wound), changes in DAO activity in the intestine were similar to those with radiation alone; plasma DAO activity, in contrast to radiation alone, did not show an increase at the 2-day mark. These dose-dependent relationships should provide a basis for using DAO as a potential indicator of biological damage from radiation exposure within the lethal range.

Amine Oxidase (Copper-Containing)↗
PubMed1987

16,16-Dimethyl prostaglandin E2 increases survival in mice following irradiation.

16,16-Dimethyl prostaglandin E2 (DiPGE2), a stable analog of PGE2, increases the LD50/30 survival in CD2F1 male mice when given prior to ionizing radiation. Subcutaneous administration of 40 micrograms of DiPGE2 30 min prior to 60Co gamma irradiation extends the LD50/30 from 9.39 Gy in the control animals to 16.14 Gy in DiPGE2 treated, with a dose reduction factor of 1.72 [95% confidence limits: 1.62, 1.82]. The degree of protection is dependent on both the time of administration and the dose of the prostaglandin. Ten micrograms administered 5 min prior to receiving a lethal dose of 10 Gy provides 90% survival but only 10% survival if administered 30 min prior to irradiation. Experiments to determine the in vivo concentration of DiPGE2 in organs postinjection show increased levels over time, but these are not correlated with protection. At 30 min after injection, as much as 80% of the DiPGE2 present in the spleen and plasma is unmetabolized. These results suggest that the protection results from the physiologic action of DiPGE2 rather than direct in vivo detoxification of radicals.

Animals↗
PubMed1986

Radioprotective properties of detoxified lipid A from Salmonella minnesota R595.

In the past, the toxicity of bacterial lipopolysaccharide (LPS) or its principal bioactive component, lipid A, has detracted from their potential use as radioprotectants. Recently, a relatively nontoxic monophosphoryl Lipid A (LAM) that retains many of the immunobiologic properties of LPS has been isolated from a polysaccharide deficient Re mutant strain of Salmonella minnesota (R595). The ability of the native endotoxic glycolipid (GL) from S. minnesota (R595) as well as diphosphoryl lipid A (LAD) and nontoxic monophosphoryl lipid A (LAM) derived from GL to protect LPS responsive (CD2F1 or C3H/HeN) and nonresponsive (C3H/HeJ) mice from 60Co gamma irradiation has been studied. Administration of GL, LAD, or LAM to CD2F1 or C3H/HeN mice (400 micrograms/kg) 24 h prior to exposure provided significant radioprotection. No protection was afforded to C3H/HeJ mice. Experiments were also conducted to determine the relative abilities of GL, LAD, and LAM to stimulate hematopoiesis as reflected by the endogenous spleen colony (E-CFU) assay. Protection was not correlated with the ability of these substances to increase E-CFUs or to induce colony-stimulating activity (CSA).

Animals↗
PubMed1985

Radiation effects on diamine oxidase activities in intestine and plasma of the rat.

Diamine oxidase (DAO; EC 1.4.3.6) activity was measured in plasma and in ileal tissue homogenates prepared from male Sprague-Dawley rats euthanized at 1-15 days after acute whole-body irradiation with 14.5-MeV electrons. Animals irradiated with 1 Gy showed no diminution in plasma and ileal DAO activities through Day 13 relative to nonirradiated controls. Animals irradiated with 5, 10, and 12 Gy displayed marked declines in ileal DAO activity, with levels reaching a nadir on Day 3. This was paralleled by a decrease in plasma DAO activity in all three dose groups. Recovery of ileal and plasma DAO levels was later seen as early as Day 4 in animals irradiated with 5- and 10-Gy doses, but animals receiving 12 Gy did not survive beyond Day 3. The relationship between radiation dose and levels of plasma and ileal DAO on Day 3, the time of maximum decrease at all doses, was also investigated. Ileal DAO activity decreased almost linearly between 2 and 8 Gy. Plasma DAO activity closely paralleled the dose dependency of the ileal levels. These data suggest that plasma DAO activity might be useful as a biologic marker of intestinal epithelial injury and recovery after acute radiation exposure.

Amine Oxidase (Copper-Containing)↗
PubMed1984

Immunologic response to protein immobilized on the surface of liposomes via covalent azo-bonding.

A new method for immobilizing protein on the surface of liposomes is described. Inclusion of N-(p-aminophenyl) stearylamide in the lipid composition of vesicles resulted in liposomes that could be 'activated' by diazotization with NaNO2/HCl, and subsequently coupled with protein. Using this method 39.7 +/- 7.5 micrograms egg albumin/mumol phospholipid has been coupled to multilamellar vesicles composed of phosphatidylcholine, cholesterol, and N-(p-aminophenyl) stearylamide in a molar ratio of 15:75:1.1. Furthermore, when the immunologic response of mice to egg albumin that was encapsulated in, nonspecifically absorbed, or covalently linked to liposomes was investigated, only the covalent protein-liposome conjugates elicited pronounced and sustained elevations in antibody titers. These results suggest that the immunoadjuvant effects of liposomes can be maximized by covalently linking protein antigens to their surface.

Albumins↗
PubMed1978

Biologic properties of bacterial lipopolysaccharides treated with chromium chloride.

Addition of small amounts of chromium chloride to a saline suspension of Salmonella typhosa lipopolysaccharide (LPD; Difco) caused a marked reduction in several of the biologic activities of this substance including toxicity, B-cell mitogenicity, plasma colony-stimulating activity (CSA), radioprotective effect, and induction of the dermal Shwartzman reaction. Nevertheless, LPS treated with chromium chloride was found to be at least as effective as untreated LPS in enhancing resistance of B6CBF1 mice to the lethal effects of Klebsiella pneumoniae infection.

Adjuvants, Immunologic↗
PubMed1977

Role of zinc in the abatement of hepatocellular damage and mortality incidence in endotoxemic rats.

Intraperitoneal administration of zinc (ZnIP) as zinc chloride prior to or simultaneously with a lethal quantity of intraperitoneally administered Salmonella typhimurium endotoxin significantly protected rats against toxin-induced mortality and hepatocellular damage. Pretreatment with amounts of zinc chloride ranging from 0.4 to 2.0 mg/100 g of body weight resulted in 80 to 100% survival compared with 10% survival in untreated control rats at 24 h after endotoxin treatment. Zinc chloride treatment in excess of 2.0 mg/100 g of body weight appeared to be toxic and provided diminished protection. In contrast with the protection obtained with ZnIP, intravenously administered zinc did not provide protection. The effectiveness of ZnIP to enhance survival if it was given after endotoxin was greatly diminished as a function of time after endotoxin. The extent of hepatocellular damage was assessed at various times after endotoxin administration in ZnIP-treated and untreated rats by measurement of plasma ornithine carbamoyltransferase activity and histological examination of liver sections. Endotoxin absorption from the peritoneal cavity and hepatic uptake were studied by using 51Cr-labeled endotoxin. ZnIP pretreatment significantly reduced 51Cr-labeled endotoxin content of blood and liver when compared to untreated controls, and effectively prevented endotoxin-induced elevations in plasma ornithine carbamoyltransferase activity and hepatic tissue necrosis. These data indicate that protection afforded by ZnIP treatment results as a consequence of the ability of zinc to diminish absorption of the toxin from the peritoneal cavity and subsequent hepatic uptake.

Absorption↗