ISSN:0098-4108    

DOI:10.1080/15287399509532045

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

It has been suggested that glass fibers in the respirable size range may pose a health hazard similar to asbestos because of the similarities in physical characteristics. To compare the pulmonary cell response with that described earlier with crocidolite asbestos, we administered a milled fiberglass sample to mice by intratracheal instillation. Little effect was seen at a dose of 0.1 mg, but at 1 mg there was epithelial injury and an inflammatory cell response concentrated at bronchiolar‐alveolar duct regions. Cellular incorporation of tritiated thymi‐dine showed that repair of both bronchiolar and alveolar epithelium occurred rapidly. This was followed by an extended increase in cell labeling, particularly in peribronchiolar fibroblasts, from 2 to 8 wk alter fiber instillation. Cranulomas formed at this site and later there was morphologic evidence of fibrosis, which was confirmed biochemically by a significant increase in lung collagen at 4–16 wk. Although 10 times higher dose is required, the results show that the lung response to fiberglass in this experimental system is similar to that described previously for crocidolite asbestos; the sites of cell injury and repair are the same, and the subsequent fibrotic response produces small airway disease.

ISSN:0098-4108    

DOI:10.1080/15287399509532046

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Occupational exposure to grain dusts can cause bronchitis, particularly to grain sorghum dust. Bronchitis is associated with the presence of increased numbers of neutrophils. To determine how grain dusts could cause neutrophil recruitment to the airways, extract of whole‐grain sorghum, corn, and soybean dusts and of pulverized components of these plants were made with Hanks balanced salt solution (HBSS) and used in direct neutrophil chemotaxis experiments. The glume of the grain sorghum plant, the structure holding the seeds in place, caused the migration of the greatest number of neutrophils compared to HBSS [132 ± 7 vs. 60 cells/high‐power field (hpf) ± 2 SEM,p< .001], followed by whole‐grain sorghum dust (121 ± 5 cells/hpf). Next, bovine bronchial epithelial cells (BBECs) were obtained from fresh lungs and grown to near confluence before challenge with a 10% solution of grain dust and grain plant extracts. The grain sorghum glume and whole‐grain sorghum dusts caused release of the greatest amount of neutrophil chemotactic activity (NCA) from BBECs compared to the medium M199 negative control (141 ± 6 and 153 ± 7, respectively, vs. 64 cells/hpf ± 3 SEM,p< .001). The ability to cause neutrophils to migrate by direct and indirect means did not correlate with levels in the grain dusts of endotoxin, which is known to cause release of NCA from bronchial epithelial cells. Therefore, this article describes additional mechanisms by which grain dusts can cause pulmonary inflammation and that are independent of endotoxin levels

ISSN:0098-4108    

DOI:10.1080/15287399509532047

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Covalent binding of radiolabel to tissue proteins following [14C]trichloroethene (TRI) exposure has been used as a measure of TRI activation. Cross binding of14C label does not differentiate between alternate routes of metabolism and can be confounded when there is significant metabolic incorporation of radiolabel. We examined the covalent association of14C label to hepatic and renal proteins in male F344 rats and B6C3F1 mice following oral treatment with [14C]TRI and three metabolites of TRI: [14C]trichloroacetate (TCA), [14C]dichloro‐acetate (DCA), and [14C]dichlorovinylcysteine (DCVC) in vivo. Association of radiolabel from [14C]TRI with hepatic proteins reached a maximum at 2 and 4 h in mouse and rat hepatic proteins, respectively. Association of radiolabel with renal proteins reached a maximum at 8 h in both species. An approach was developed based upon formation of protein adducts that release acetate and monochloroacetate (MCA) on acid hydrolysis. These adducts were found to be specifically associated with the activation of DCVC to reactive intermediates. Acetate and MCA were identified by using two different conditions of high‐performance liquid chromatography (HPLC) separation with differing selectivity. Diethylmaleate and aminooxyacetic acid pretreatment inhibited the formation of these adducts from TRI, consistent with requirements for glutathione and β‐lyase. No evidence of these adducts was detected following [14C]TCA and [14C]DCA treatment. Renal acid‐labile adduct formation from 25 mg/kg DCVC was approximately 12‐fold greater in male B6C3F1 mice than in male F344 rats. They accounted for 7.8 and 4.6% of the total adducts to renal protein in rats and mice, respectively. Acid‐labile adducts formed from 1000 mg/kg TRI were approximately two times greater in mice than rats. In this case, they accounted for 1.4 and 3.3% of the total adduct formed in renal proteins from TRI (corrected for metabolic incorporation), respectively. This greater dilution of adducts associated with DCVC in renal proteins of the rat suggests that covalent binding of TRI has less specificity for the DCVC pathway in rats than in mice.

ISSN:0098-4108    

DOI:10.1080/15287399509532048

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Covalent binding of reactive intermediates formed by renal β‐lyase activation ofS‐(1,2‐dichlorovinyl)‐L‐cysteine (DCVC) has been suggested to be responsible for the greater renal sensitivity of rats than mice to the carcinogenic effects of chronic treatment with trichloroethene (TRI). Previous work demonstrated that the activation of DCVC results in acid‐labile adducts to protein that can be distinguished from adducts formed by other pathways of TRI metabolism. By analyzing acid‐labile adduct formation, the relationship between DCVC formation and activation from TRI and increases in rates of cell division in the kidneys of male F344 rats and B6C3F1 mice could be investigated. The delivered dose of DCVC from an oral dose of 1000 mg/kg TRI was approximately six times greater in rats than mice. However, renal activation of DCVC in mice was approximately 12 times greater than in rats. Therefore, the overall activation of TRI was about two times greater in mice than rats. Induction of cell replication in liver and kidney following doses of 1, 5, or 25 mg/kg DCVC or 1000 mg/kg TRI was also measured through the use of miniosmotic pumps that delivered BrdU subcutaneously for 3 d. Acid‐labile adduct formation from DCVC and TRI displayed a consistent relationship with increased cell replication in mice and between mice and rats. Both cell replication and acid‐labile adduct formation in rats given 25 mg/kg DCVC were approximately equal to that observed in mice given 1 mg/kg. Increased cell replication was not observed in rats receiving 1 or 5 mg/kg DCVC or WOO mg/kg TRI, nor were there histological signs of nephrotoxicity. Thus, net activation of TRI by the cysteineS‐conjugate pathway was found to be greater in mice than rats and these findings appeared related to differences in cell proliferative responses of the kidneys of the two species. Based on these data, it would appear that other factors must contribute to the greater sensitivity of the rat to the induction of renal carcinogenesis by TRI.

ISSN:0098-4108    

DOI:10.1080/15287399509532049

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The process of ecological risk assessment should involve the ability to predict adverse outcomes of particular environmental contaminants or human intrusions. Ecological risk assessment generally focuses on populations, communities, and ecosystems, rather than on individual health. We explore the importance of life history strategies of aquatic turtles to their risk from environmental contaminants and other human activities using three examples: the wood turtleClemmys insculpta, a freshwater species; the diamondback terrapinMalaclemys terrapin, a littoral species; and marine turtles as a group. These turtles are partly herbivorous and are at low or intermediate levels on the food chain, yet are particularly vulnerable due to their life history strategies of being long‐lived with relatively low survival of young. They suffer a variety of natural mortality factors that include predation, starvation, and disease, as well as inundation and destruction of nesting beaches and their eggs by storms. Yet they also face a number of anthropogenic hazards, including toxic chemicals and floatables (plastics); capture for food, other products, and pets; incidental mortality in fishing gear; disturbance while nesting or moving on land; injuries or death by collision with boats; and increased predator exposure because of humans. The three turtle species (or groups of species) examined have experienced these natural and anthropogenic pressures differentially, with resultant differences in the rates of population declines. Because they are lower on the food chain than other obligate carnivores, they are less vulnerable to toxics, and to date, toxics seem a relatively inconsequential environmental risk to turtles

ISSN:0098-4108    

DOI:10.1080/15287399509532050

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The estuarine dinoflagellate Pfiesteria piscicida gen. et sp. nov. produces exotoxin(s) that can be absorbed from water or fine aerosols. Culture filtrate (0.22 μm porosity filters, >250 toxic flagellated cells/ml) induces formation of open ulcerative sores, hemorrhaging, and death of finfish and shellfish. Human exposure to aerosols from ichthyotoxic cultures (≥2000 cells/ml) has been associated with narcosis, respiratory distress with asthma‐like symptoms, severe stomach cramping, nausea, vomiting, and eye irritation with reddening and blurred vision (hours to days); autonomic nervous system dysfunction [localized sweating, erratic heart beat (weeks)]; central nervous system dysfunction [sudden rages and personality change (hours to days), and reversible cognitive impairment and short‐term memory loss (weeks)]; and chronic effects including asthma‐like symptoms, exercise fatigue, and sensory symptoms (tingling or numbness in lips, hands, and feet; months to years). Elevated hepatic enzyme levels and high phosphorus excretion in one human exposure suggested hepatic and renal dysfunction (weeks); easy infection and low counts of several T‐cell types may indicate immune system suppression (months to years). Pfiesteria piscicida is euryha‐line and eurythermal, and in bioassays a nontoxic flagellated stage has increased under P enrichment (≥ 100 μg SRP/L), suggesting a stimulatory role of nutrients. Pfiesteria‐like dinoflagellates have been tracked to fish kill sites in eutrophic estuaries from Delaware Bay through the Gulf Coast. Our data point to a critical need to characterize their chronic effects on human health as well as fish recruitment, disease resistance, and survival.

ISSN:0098-4108    

DOI:10.1080/15287399509532051

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/15287399509532044

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor