摘要:

Respirable-sized quartz and kaolin dusts were pretreated with simulated pulmonary surfactant dispersions of dipalmitoyl phosphatidylcholine (DPPC) in saline to model the conditioning of particles depositing in alveolar regions of the lung. DPPC-treated and untreated dusts were used to challenge lavaged rat pulmonary alveolar macrophages in vitro. Cytotoxicity was determined over a 5-d period using both total and viable cell counts from a fluorescence-based viability assay. DNA damage, as an indication of genotoxicity, was determined over a 7-d period by the single-cell gel electrophoresis assay. Untreated quartz and kaolin both expressed a significant and potent cytotoxicity, which increased with concentration and time. DPPC-surfactant pretreatment delayed significant expression of this cytotoxicity until 3 to 5 d after challenge. Untreated quartz also caused DNA damage, which increased with concentration and time. DPPC-surfactant treatment of quartz delayed most DNA damage expression to 5 and 7 d. Untreated kaolin expressed weaker activity for DNA damage, significant at the highest concentration through 5 d, and at the higher concentrations on d 7. Surfactant treatment delayed most kaolin activity for DNA damage to 7 d after challenge.

ISSN:1528-7394    

DOI:10.1080/009841000156466

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

A distillate of light catalytic reformed naphtha (CAS number 64741-63-5, LCRN-D) administered by inhalation was tested for reproductive and developmental toxicity in Sprague-Dawley rats, following a modified OECD Guideline 421, Reproductive/Developmental Toxicity Screening protocol. LCRN-D was administered as a vapor, 6 h/d, 7 d/ wk at target concentrations of 0, 750, 2500 or 7500 ppm to female rats for approximately 6 wk from 2 wk prior to mating, during mating through gestational d 19, and to males beginning 2 wk prior to mating for approximately 7 consecutive weeks. Dams and litters were sacrificed on postnatal d 4 and males were sacrificed within the week after the last litter was necropsied. Parental systemic effects observed at the 7500 ppm exposure level included slightly lower body weights for males throughout the study. Increased kidney to body weight and increased liver to body weight ratio in male rats exposed to 7500 ppm LCRN-D may be related to slightly lower final mean body weights. Body and organ weight data for female rats in all exposure groups were comparable to controls. No test-material-related microscopic changes were observed in the reproductive organs or nasal turbinate tissue of either sex. Reproductive performance was unaffected by exposure to LCRN-D. The mating and fertility indices were 100% in all groups. There were no significant exposure-related differences in implantation sites or live pups per litter, and no gross abnormalities were observed in pups from treated dams. Pups born from LCRN-D-exposed dams showed comparable body weights and weight gain to control pups. The viability index on postpartum d 4 was 97%. Under conditions of this study, the no-observed-adverse-effect level (NOAEL) for exposure to light catalytic reformed naphtha distillate for parental effects was 2500 ppm and the NOAEL for reproductive and developmental toxicity was 7500 ppm.

ISSN:1528-7394    

DOI:10.1080/009841000156475

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Eight-week-old female and male NMRI mice treated neonatally with the synthetic estrogen diethylstilbestrol (DES), estradiol-17 b , or tamoxifen displayed an enlarged thymus when compared with controls (approximately 1.5-fold). In control females, either ovariectomy or adrenalectomy increased thymus weight to the level characteristic for DEStreated females, but these endocrine ablations had no significant effect in DES females. The serum estrogen levels were similar in intact DES, ovariectomized DES, and ovariectomized female controls; serum corticosterone was similar in controls and DES females. The expression of the Thy1.2+ marker and the percentages of CD4+CD8+ DP and CD4+ and CD8+ SP cell subsets were similar in thymocyte populations from 8-wk-old controls and DES females; the CD4+ and CD8+ SP subsets were similar in splenocyte populations. The levels of serum immunoglobulin (Ig) G and IgM autoantibodies to cardiolipin showed age-dependent fluctuations but were similar in controls and DES females; however, the IgG autoantibodies in DES females were qualitatively different from those in controls with respect to sensitivity to bovine serum (a source of Beta2-glycoprotein I). Contrary to females, DES-treated males had higher levels of autoantibodies than controls. The delayed-type hypersensitivity (DTH) response to oxazolone was similar in controls and DES animals at 8 wk, increased in DES females and males at 6 mo, but was reduced in DES females at 1 yr. Thus, even though adult mice with thymus enlargement after neonatal estrogen treatment do not differ from controls with respect to the expression of the Thy1.2 marker or percentages of CD4+/CD8+ DP or SP subsets in thymus and spleen, qualitative and quantitative differences occur in immune parameters (autoantibodies to cardiolipin) and a T-cell-dependent immune response (DTH).

ISSN:1528-7394    

DOI:10.1080/009841000156484

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor

摘要:

Blackfoot disease (BFD) is a peripheral arterial occlusive disease found among human inhabitants along the southwest coast of Taiwan. Well water used for drinking and cooking contains humic acid (HA), which may be a possible etiological factor. In this study, HA toxicity was investigated in human erythrocytes and was found to induce echinocytic formation. Morphological changes occurred in both a concentration- and time-dependent fashion. The presence of HA was also observed to facilitate the loading of erythrocytes with excess Ca2+(1 mM), which may have occurred following permeability changes in cell membranes, leading to echinocytic transformations. Sodium dodecyl sulfate (SDS) gel electrophoresis indicated that echinocyte formation was due to the oxidation of normal membrane proteins that were replaced by high-molecular-weight proteins. Humic acid also induced hemoglobin oxidation in erythrocytes. Data show that oxidative stress generated by HA as well as direct effects were exerted on the cytoskeleton of erythrocytes, and these may be significant factors in the etiology of BFD.

ISSN:1528-7394    

DOI:10.1080/009841000156493

出版商:Informa UK Ltd    

年代:2000

数据来源: Taylor