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Biomedical subjects

D Stanton

Publications and source records attributed to D Stanton.

5 recordsLinked to original sources
PubMed1992

Depolymerization of heparin by complexed ferrous ions.

Treatment of porcine heparin with the ferrous-EDTA complex and ascorbic acid for 24 h at 37 degrees C results in the degradation of most of the glycosaminoglycan to smaller fragments. About 65% of the products comprise oligosaccharides composed of less than 30 sugar units. The extent of depolymerization is decreased significantly if ascorbate or EDTA is not included in the reaction mixture. Gel filtration of the reaction products yielded fractions with narrow chain length ranges. The sulfate content of the fractions and their electrophoretic mobilities on cellulose acetate indicate that the components have equivalent charge densities. Depolymerization products with 20 or more sugar units retain significant anticoagulant potencies as measured by their effect in accelerating the neutralization of factor Xa by antithrombin.

Animals↗
PubMed1992

Diagnostic accuracy of three clinical case definitions for advanced HIV disease.

OBJECTIVE: To assess the accuracy of three clinical case definitions for advanced HIV disease: the World Health Organization (WHO) case definition, and the original and revised Caracas case definitions. DESIGN: Retrospective chart review. SETTING: A clinic for patients with all stages of HIV infection at the Johns Hopkins Hospital, Baltimore, [correction of Bethesda] Maryland, USA, a tertiary care university hospital. PATIENTS, PARTICIPANTS: Two hundred and twenty-four HIV-positive adults who underwent initial evaluation between 1 January 1990 and 31 December 1990. MAIN OUTCOME MEASURES: A score for each definition was assigned based on initial evaluation. The sensitivity, specificity, and predictive values were calculated using the Centers for Disease Control (CDC) staging criteria, and results were correlated with total CD4 cell counts. RESULTS: The sensitivities of the WHO, and the original and revised Caracas definitions were 40, 67, and 60%, respectively, using CDC disease stage IV as a positive standard. Specificities were between 99 and 100%, using CDC stage II-III disease as a negative standard. Mean CD4 cell counts for patients with positive scores were 184, 160, and 158 x 10(6)/l, respectively, compared to 191 x 10(6)/l for CDC stage IV patients. Sensitivity was lower when the positive standard was expanded to include all patients with CD4 cell counts less than 200 x 10(6)/l. CONCLUSIONS: In our study population, case definitions were specific, but only moderately sensitive for advanced HIV disease. Prospective studies should be conducted in diverse geographic regions, using lymphocyte or CD4 cell counts when possible.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Protection by cysteine esters against chemically induced pulmonary oedema.

Perfluoroisobutene (PFIB) is a hydrophobic reactive gas produced by the pyrolysis of polytetrafluoroethane which induces pulmonary oedema similar to that induced by phosgene when inhaled. When a lethal dose is inhaled by Porton strain rats total non-protein thiol (NPSH) and glutathione (GSH) in the lung are reduced by between 30 and 49%, respectively. If the endogenous levels of thiols in the lung are reduced by pretreatment with buthionine sulfoximine (BSO) 16 hr before exposure to PFIB, the rats become more susceptible to the effects of the gas. The effect of BSO pretreatment on toxicity was prevented by pretreatment 30 min before exposure, with 5 mmol/kg N-acetylcysteine (NAc). NAc increased the levels of cysteine (CySH) in the lung by 150% and GSH was unaffected. Similarly pretreatment with 3 mmol/kg CySH also protected against toxicity and raised CySH levels by 100%. A series of cysteine esters and cystine dimethyl ester (CDME) have been synthesised which selectively raise lung levels of CySH in the rat lungs after intraperitoneal (i.p.) injection. The methyl ester and CDME raised lung levels of CySH by 4000 and 2000%, respectively, 10 min after i.p. injection whilst GSH levels remained unchanged. Cysteine isopropyl ester raised lung levels of CySH by 10,600% but liver levels by only 1400%. All esters except the t-butyl ester (CTBE) also raised maximal plasma levels of NPSH by up to 500%; however, when NAc was injected plasma levels increased by over 1500%. Rats treated with these esters at 3 mmol/kg and with NAc at 5 mmol/kg were protected against lethal doses of PFIB in all cases except when CTBE was used. It appears that these cysteine esters may distribute preferentially into the lung, unlike NAc. The selective enhancement of pulmonary CySH levels may provide a method for the protection of lungs against inhaled reactive toxicants by increasing intracellular CySH. Levels of CySH may also be raised in epithelial lining fluid thus reducing access of gaseous toxicants to pulmonary tissue.

Acetylcysteine↗