ISSN:1528-7394    

DOI:10.1080/009841000156655

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Chrysotile and crocidolite fibers incubated in normal human plasma (NHP) generated from the C5component of complement C5a-type fragments that stimulated polymorphonuclear leukocyte (PMN) chemotaxis. Absorption of NHP with antiserum against C5atotally abolished neutrophil chemotactic activity. Asbestos fibers also produced C5asmall peptides in the presence of ethylene glycol bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) but not ethylene diamine tetraacetic acid (EDTA). Activation of C5was significantly inhibited when asbestos fibers were pretreated with iron chelators such as sodium dithionite (DTN), deferoxamine (DFX), or ascorbate (AA). Concentration-related inhibition of C5activation was also observed when asbestos fibers were added concurrently to plasma in the presence of DFX, 1,3-dimethyl-2-thiourea (DMTU), a strong hydroxyl scavenger, or aprotinin (APR), a specific protease inhibitor. Further, chrysotile and crocidolite significantly increased plasma kallikrein activity. Data demonstrate that asbestos-induced C5activation plays a role in inflammatory reactions characteristic of asbestosis through mechanisms involving iron ions, hydroxyl radicals, and oxidized C5-like fragments. The ferrous ions present at the asbestos fiber surface trigger this activation and catalyze, via Fenton reaction, the production of hydroxyl radicals, which in turn convert native C5to an oxidized C5-like form. This product is then cleaved by kallikrein, activated by the same asbestos fibers, yielding an oxidized C5awith the same functional properties as C5a.

ISSN:1528-7394    

DOI:10.1080/009841000156664

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

This study was undertaken to investigate the effects of selenium dioxide (SeO2) on rat blood and femoral bone-marrow oxidant mechanisms. Treatment with SeO2, 67mug Se/kg ip daily for 14 d, significantly decreased lipid peroxidation and the concentrations of Fe in serum and bone marrow. The concentrations of Se in serum and bone-marrow cells were significantly increased after SeO2treatment. The activities of glutathione peroxidase (GPx) in blood and bone-marrow cells were markedly increased. The levels of oxyhemoglobin in blood were significantly increased, while the concentrations of methemoglobin were decreased after SeO2administration. The fragility of erythrocytes membranes was significantly decreased in SeO2-treated rats compared to controls. Data suggest that treatment with a low dose of SeO2may provide antioxidant nutrients to blood and bone marrow.

ISSN:1528-7394    

DOI:10.1080/009841000156673

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Associations between immunoglobulin G (IgG) levels and the organochlorine contaminants (OCs) polychlorinated biphenyls (PCBs), chlordanes, 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs) in blood plasma from polar bears caught at Svalbard were determined. The blood samples were collected from free-living polar bears of different age and sex between 1991 and 1994. The IgG concentration increased with age and was significantly higher in males than in females. IgG was negatively correlated withSigmaPCB level and with three individual PCB congeners, IUPAC numbers 99, 194, and 206. HCB was also negatively correlated with IgG. The significant negative OC correlation with IgG levels may indicate an immunotoxic effect.

ISSN:1528-7394    

DOI:10.1080/009841000156682

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Zinc (Zn) is a nutritionally essential metal, and deficiency results in severe health consequences to aquatic organisms. In this study toxicity data for Limnodrilus hoffmeisteri produced by Zn in systems using three natural sediments (trout farms: El Oyamel, El Truchon, and El Potrero) are presented. Hemoglobin, adenosine triphosphate (ATP), and protein concentrations were measured in L. hoffmeisteri exposed to spiked sediments, as indicators of exposure. Physicochemical characteristics of water and sediments were also considered. Zn concentrations were measured in water and sediment. El Oyamel, El Truchon, and El Potrero pond sediments did not have similar physicochemical characteristics. Zn concentrations of water obtained from the rustic ponds were near 0.4575 mg/ L; however, this metal was always found to be higher in the sediments (0.0271-0.9754 mg/kg). The bioassay with worms demonstrated that pond sediments from El Oyamel, El Potrero, and El Truchon produced toxicity since ATP and protein concentrations were low compared to controls (organisms without metal). All spiked sediments had a significant reduction effect on ATP, protein, and hemoglobin concentrations. This investigation clearly shows that sediments of El Truchon, El Oyamel, and El Potrero possess toxicity potential. These results suggest the usefulness of these bioassays to evaluate the toxicity of sediments polluted with heavy metals.

ISSN:1528-7394    

DOI:10.1080/009841000156691

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Antioxidant defense capacity was investigated in myocardial tissue from guinea pigs treated with 5-fluorouracil (5-FU) at a dose of 400 mg/kg/d daily for 5 d administered intraperitonally. Treatment with 5-FU lowered the activities of cardiac superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) accompanied by higher catalase (CAT) activity. Further, antioxidant potential (AOP) values were lower but oxidation resistance (OR) and malondialdehyde (MDA) levels were higher in the 5-FU-treated tissue. With regard to myocardial iron (Fe) and copper (Cu) levels, no significant differences were found between the groups. Results suggest that 5-FU treatment causes impairment in the myocardial antioxidant defense system and leads to cardiac peroxidation. It has been postulated that these changes might be responsible for the 5-FU cardiotoxicity seen in some patients, and antioxidant therapy might provide a therapeutic advantage.

ISSN:1528-7394    

DOI:10.1080/009841000156709

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor