PubMed Health⌕ Search

Biomedical subjects

S W Cooper

Publications and source records attributed to S W Cooper.

8 recordsLinked to original sources
PubMed1995

Identification and characterization of a tolerogenic T cell determinant within residues 181-209 of chick type II collagen.

The murine model of collagen-induced arthritis is characterized by the development of an immune response against joint cartilage. Arthritis can be significantly suppressed by the administration of type II collagen (CII) or one of the CNBr peptides, CB11 (CII 124-402) as a tolerogen prior to immunization. We have previously shown that two synthetic peptides, representing sequences CII 260-270 and CII 181-209, are effective tolerogens. In this paper, we now characterize the T cell determinant with CII 181-209. A series of synthetic peptides overlapping CII 181-209 and analogs of chick CII 181-209 containing site-directed amino acid substitutions was developed and cultured with T cells from DBA/1 mice immunized with CII. Supernatants were collected and analyzed for the presence of the T cell lymphokine IFN-gamma. These data indicate the critical T cell determinant to be located within CII 190-200. This conclusion is further supported by the observation that an unodecapeptide representing CII 190-200 was just as effective as CII 181-209 in suppressing arthritis and anti-CII antibody response when tested as a tolerogen. Analogs containing single amino acid substitutions at residues 191, 194, 197, 198, or 200 were significantly less effective in inducing T cell responses. Each of these peptide analogs was then given as neonatal tolerogens to DBA/1 mice. Mice were subsequently immunized and observed for the development of arthritis. These studies identified residues 194, 197, 198, and 200, and probably residue 191, as critical for tolerance and the suppression of arthritis. Elucidation of the fine structures of T cell determinants which are critical for suppression of arthritis should allow these techniques to be used for developing specific immunotherapeutic approaches to autoimmune arthritis.

Amino Acid Sequence↗
PubMed1991

Dermal absorption of neat and aqueous volatile organic chemicals in the Fischer 344 rat.

Quantification of dermal absorption of volatile organic chemicals (VOCs) from aqueous solutions is required to understand the potential health hazards resulting from skin exposure to these chemicals in contaminated water. Male Fischer 344 rats were dermally exposed (3.1-cm2 dorsal skin) to neat, one-third saturated, two-thirds saturated, or saturated aqueous solutions of 14 VOCs for 24 hr. Blood samples were obtained via indwelling jugular catheters during exposure (0, 0.5, 1, 2, 4, 8, 12, and 24 hr), and analyzed for the VOCs by gas chromatography using headspace analysis. Absorption of the neat VOCs in this series of chemicals decreased as water solubility decreased. Peak blood levels of VOCs attained during exposure for 24 hr to neat chemicals were: 1,2-dichloroethane (135.1 micrograms/ml), bromochloromethane (113.3 micrograms/ml), chloroform (51.0 micrograms/ml), benzene (24.2 micrograms/ml), tetrachloroethylene (21.1 micrograms/ml), dibromomethane (18.2 micrograms/ml), trichloroethylene (11.6 micrograms/ml), toluene (9.5 micrograms/ml), xylene (8.8 micrograms/ml), hexane (8.0 micrograms/ml), ethylbenzene (5.6 micrograms/ml), styrene (5.3 micrograms/ml), carbon tetrachloride (5.0 micrograms/ml), and 1,1,1-trichloroethane (3.4 micrograms/ml). Blood levels of 1,2-dichloroethane and benzene continued to increase during the 24-hr exposure to neat chemical, while blood levels of the other neat VOCs peaked within 4 hr and then either decreased or remained about the same for the duration of the exposure. Absorption of VOCs from one-third, two-thirds, or saturated aqueous solutions was rapid, and resulted in depletion of the chemical from the solution although only a small amount of water was absorbed. Blood levels of each VOC were directly related to the exposure concentrations. The rapid appearance of VOCs in the blood from aqueous solutions demonstrates that detectable amounts of VOCs were absorbed during exposure of only about 1% of the skin surface area of the rat.

Animals↗
PubMed1985

Evaluation of xylan fermentation for the identification of Bacteroides ovatus and Bacteroides thetaiotaomicron.

The reliability of xylan fermentation in distinguishing Bacteroides ovatus from Bacteroides thetaiotaomicron was examined with strains previously identified by DNA homology studies or bacteriophage sensitivity testing or both. All of the 12 B. ovatus strains produced acid ranging from pH 5.0 to 5.6 in peptone-yeast-xylan broth; none of the 19 B. thetaiotaomicron strains produced acid, and the final pH was 6.0 or 6.1. Xylan fermentation and bacteriophage sensitivity-DNA homology appear to be equivalent in their ability to differentiate these two Bacteroides species.

Bacteriophage Typing↗
PubMed1984

Differentiation of Bacteroides ovatus and Bacteroides thetaiotaomicron by means of bacteriophage.

Two members of the Bacteroides fragilis group, B. ovatus and B. thetaiotaomicron, are difficult to distinguish by biochemical methods. They are currently identified on the basis of their variable ability to ferment salicin. We studied a method of identification for these two species by using cell lysis by bacteriophages. A total of 38 bacteriophages were used to distinguish the two species. Identification by bacteriophages was compared with species identification by prereduced anaerobically sterilized biochemical testing with salicin as the differentiating test. A total of 215 clinical isolates biochemically identified as B. ovatus or B. thetaiotaomicron were tested. A total of 100% of the strains identified as B. ovatus by bacteriophages produced strong acid in salicin (pH less than or equal to 5.4). However, 40% of the strains identified as B. thetaiotaomicron by bacteriophages also produced strong acid in salicin, and an additional 39% produced weak acid (pH 5.5 to 5.7). This study demonstrates that salicin fermentation is an inadequate test for the differentiation of B. ovatus and B. thetaiotaomicron.

Bacteriophage Typing↗
PubMed1981

Complement activation during cardiopulmonary bypass: evidence for generation of C3a and C5a anaphylatoxins.

We observed complement activation in 15 adults undergoing total cardiopulmonary bypass. Plasma levels of C3a were significantly elevated (P < 0.0001) at the beginning of the procedure, and they continued to increase steadily thereafter. At the end of the procedure, C3a levels were more than five times higher than preoperative levels. Plasma levels of C5a (a factor that binds avidly to neutrophils) did not change significantly during cardiopulmonary bypass. Instead, there was significant neutrophilia (P = 0.03) during bypass, and significant transpulmonary neutropenia (P = 0.0002) occurred when cardiopulmonary circulation was reestablished at partial bypass. The neutropenia is consistent with pulmonary-vascular sequestration of C5a-activated granulocytes. We also found that incubation of blood with the nylon-mesh liner of bubble oxygenators, as well as vigorous oxygenation of whole blood, promotes conversion of complement. We conclude that the complement-derived inflammatory mediators C3a and C5a produced during extracorporeal circulation may contribute to the pathogenesis of "post-pump syndromes."

Adult↗
PubMed1980

Acute dimethylnitrosamine poisoning outbreak.

In an 8-h period, five members of two kindred families suddenly became ill with nausea, vomiting, and malaise. This was followed by acute liver disease, a generalized bleeding tendency, and a low platelet count. Two of the patients died four and five days after onset of illness. It was established that dimethylnitrosamine had been intentionally added to lemonade and milk that were consumed by the victims.

Adult↗