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Titolo:
DEPHOSPHORYLATION OF ENDOTOXIN BY ALKALINE-PHOSPHATASE IN-VIVO
Autore:
POELSTRA K; BAKKER WW; KLOK PA; KAMPS JAAM; HARDONK MJ; MEIJER DKF;
Indirizzi:
UNIV GRONINGEN,GUIDE,DEPT PHARMACOKINET & DRUG DELIVERY,ANT DEUSINGLAAN 1 NL-9713 AV GRONINGEN NETHERLANDS UNIV GRONINGEN,GUIDE,DEPT PATHOL NL-9713 AV GRONINGEN NETHERLANDS UNIV GRONINGEN,GUIDE,DEPT PHYSIOL CHEM NL-9713 AV GRONINGEN NETHERLANDS
Titolo Testata:
The American journal of pathology
fascicolo: 4, volume: 151, anno: 1997,
pagine: 1163 - 1169
SICI:
0002-9440(1997)151:4<1163:DOEBAI>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
TUMOR-NECROSIS-FACTOR; INTRACELLULAR COMPARTMENT; STAPHYLOCOCCUS-AUREUS; HUMAN-NEUTROPHILS; SEPTIC SHOCK; LIPID-A; BACTERIAL; SEPSIS; CELLS; LIPOPOLYSACCHARIDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
51
Recensione:
Indirizzi per estratti:
Citazione:
K. Poelstra et al., "DEPHOSPHORYLATION OF ENDOTOXIN BY ALKALINE-PHOSPHATASE IN-VIVO", The American journal of pathology, 151(4), 1997, pp. 1163-1169

Abstract

Natural substrates for alkaline phosphatase (AP) are at present not identified despite extensive investigations. Difficulties in imagining a possible physiological function involve its extremely high pH optimum for the usual exogenous substrates and its localization as an ecto-enzyme. As endotoxin is a substance that contains phosphate groups and is usually present in the extracellular space, we studied whether AP is able to dephosphorylate this bacterial product at physiological pH levels. We tested this in intestinal cryostat sections using histochemical methods with endotoxin from Escherichia coli and Salmonella minnesota R595 as substrate. Results show that dephosphorylation of both preparations occurs at pH 7.5 by AP activity. As phosphate residues in the lipid A moiety determine the toxicity of the molecule, we examined the effect of the AP inhibitor levamisole in vivo using a septicemia model in the rat. The results show that inhibition of endogenous AP by levamisole significantly reduces survival of rats intraperitoneally injected with E. coli bacteria, whereas this drug does not influence survival of rats receiving a sublethal dose of the gram-positive bacteria Staphylococcus aureus. In view of the endotoxin-dephosphorylating properties of AP demonstrated in vitro, we propose a crucial role for thisenzyme in host defense. The effects of levamisole during gram-negative bacterial infections and the localization of AP as an ecto-enzyme inmost organs as well as the induction of enzyme activity during inflammatory reactions and cholestasis is in accordance with such a protective role.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/09/20 alle ore 10:46:21