摘要:

Elevated levels of air pollution particulates 10 mum in diameter (PM10) have been associated with an increase in mortality and morbidity due to pulmonary complications, including pneumonia. Impairment of inflammatory and host defense functions of the alveolar macrophage (AM) may be a precipitating factor. The present study was undertaken to determine whether human AM and blood derived monocytes (MO) modulate the expression of receptors important for phagocytosis of opsonized microbes (CD11b, CD11c), gram-negative bacteria (CD14), extracellular matrix interaction (CD29), and immune responses (CD11a, CD54, HLA-DR) when exposed to particulates obtained from urban air (UAP). Furthermore, phagocytosis of and oxidant generation by opsonized yeast were investigated in particle-exposed cells. AM and MO exposed to UAP for 18 h expressed significantly lower levels of CD11b and CD29. CD14 expression was markedly decreased in MO but not in AM, and CD11c was reduced in AM but not in MO. CD11a, CD54, and HLA-DR were unaltered in both phagocyte populations. Decreased receptor expression was not dependent on particle load in the cells. Phagocytosis of Saccharomyces cerevisiae and the chemiluminescence response were also significantly inhibited by UAP. Time-course studies revealed that decreased oxidant generation was evident already at 3 h postexposure, while significant effects on phagocytosis and CD11b expression were found at 18 h. These data indicate that exposure to particulate pollution is likely to impair host defense functions of AM and MO, which are important in elimination of a variety of pathogens in the lung.

ISSN:1528-7394    

DOI:10.1080/009841098158278

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

The effects of in vitro exposure to different organochlorines were evaluated on immune functions of beluga whale peripheral blood leukocytes and splenocytes. The effects of different concentrations of four different congeners of PCBs (138, 153, 180, and 169) as well as two DDT metabolites (p,p '-DDT and p,p '-DDE) were evaluated on phagocytosis and cell proliferation. The effects of dioxins and mixtures of organochlorines were also evaluated on cell proliferation. The different compounds tested had no marked effect on phagocytosis. PCB 138 and p,p '-DDT, but not PCB 153, PCB 180, PCB 169, and p,p '-DDE, reduced significantly the proliferative response of beluga splenocytes cultured either with or without phytohemagglutinin A (PHA). Proliferation of beluga splenocytes was not markedly affected by exposure to 5 ppm of PCB 138, 153, 180, and 169 separately. Exposure to a mixture of congeners 138, 153, and 180 (5 ppm each) significantly reduced splenocytes proliferation, but not the mixture of congeners 138, 153, 180, and 169 (5 ppm each). TCDD did not affect cell proliferation in our study. The reduced proliferation of beluga cells exposed in vitro to mixtures of organochlorines at concentrations in the range of those observed in tissues of St. Lawrence belugas might provide a basis to support the hypothesis that contaminants induce immunosuppression in these animals.

ISSN:1528-7394    

DOI:10.1080/009841098158287

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

In this study the effects of lead on behavioral development of hatchling slider turtles (Trachemys scripta) from the Savannah River Site, near Aiken, SC, were examined. It was of interest to determine whether dose or size affects survival, growth, or behavior. Hatchlings from 1995 showed no significant differences in growth, survival, or behavior between control and lead-injected animals at a dose of 0.05 and 0.1 mg/g (n = 10 per group). In 1996, 48 hatchlings were divided into four groups injected with 0 (control), 0.25, 1, or 2.5 mg/g lead. Few significant differences occurred in growth or size as a function of lead treatment at 4 mo of age, but survival declined markedly as a function of lead dose. Righting response was significantly impaired by lead; time to right was directly related to lead dose. Size also affected behavior; larger hatchlings turned over more quickly and reached cover sooner than did smaller hatchlings.

ISSN:1528-7394    

DOI:10.1080/009841098158296

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Pyrene was chosen as a noncarcinogen model of polycyclic aromatic hydrocarbons (PAHs). Groups of male Wistar rats were dosed with pyrene and with mixture of pyrene and fluoranthene, pyrene and benz\[a]anthracene, or pyrene, fluoranthene, and benz\[a]anthracene at 20 mg/kg by intravenous or oral routes. Blood samples were taken at 0.25, 0.5, 1, 2, 3, 4, and 5 h after administration. The concentration of pyrene was determined by gas chromatography. The toxicokinetic parameters for pyrene were determined from the time course of blood concentration. A significant increase in the bioavailability of pyrene after treatment with other PAHs was observed. Urinary 1-hydroxypyrene excretion was analyzed after pretreatment with acenaphthene, naphthalene, chrysene, phenanthrene, benz\[a]anthracene, and benzo\[a]pyrene. The urine from rats was collected for 3 d and the concentration of 1-hydroxypyrene was determined using high-performance liquid chromatography (HPLC). Most compounds examined caused a decrease in the urinary excretion of the metabolite of pyrene.

ISSN:1528-7394    

DOI:10.1080/009841098158304

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Aflatoxin B1 (AFB1), a potent hepatocarcinogen, is known to impair specific and nonspecific immune responses. AFB1 mainly decreases lymphocyte functions and may also affect macrophages assisting lymphocyte functions. Macrophages play an important role in a host defense against tumors and bacteria. Furthermore, some macrophage products, including nitric oxide (NO), may be involved in cytotoxicity. The effect of aflatoxin B1 (AFB1) was investigated on NO production from murine peritoneal macrophages. Macrophages were pretreated with AFB1 for 24 h and then stimulated with lipopolysaccharide (LPS) for 24 h. AFB1 at 10 or 50 mu M reduced the production of NO. Compared to vehicle control, there was a greater reduction of NO production with increased AFB1 pretreatment and LPS stimulation. AFB1 at 10 or 50 mu M decreased inducible nitric oxide synthase (iNOS) activity about 24% and 28%, respectively, after stimulation with 1 mug/ml LPS and about 12% and 24%, respectively, after stimulation with 10 mug/ml LPS. AFB1 pretreatment also decreased the synthesis of iNOS protein and the mRNA of macrophages. Taken together, these results suggest that AFB1 pretreatment reduces NO production from murine peritoneal macrophages stimulated by LPS, which is mediated by the reduction of iNOS activity, mRNA, and protein.

ISSN:1528-7394    

DOI:10.1080/009841098158313

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor