摘要:

Formaldehyde (HCHO) is a common chemical found in occupational and residential environments and has been suggested as a cause of asthmalike symptoms in some individuals. Clinical and animal studies suggest that HCHO adsorbed on respirable particles may elicit a greater pulmonary physiologic and inflammatory effect than gaseous HCHO alone. The purpose of this study was to determine if respirable carbon particles have a synergistic effect on the acute symptomatic and pulmonary physiologic response to HCHO inhalation. We randomly exposed 24 normal, nonsmoking, methacholine‐nonreactive subjects to 2 h each of clean air, 3 ppm formaldehyde, 0.5 mg/m3respirable activated carbon aerosol, and the combination of 3 ppm formaldehyde plus activated carbon aerosol. The subjects engaged in intermittent heavy bicycle exercise (VE= 57 l/min) for 15 min each half hour. Measures of response included symptom questionnaires, spirometry, body plethysmography, and postexposure serial peak flows. Formaldehyde exposure was associated with significant increases in reported eye irritation, nasal irritation, throat irritation, headache, chest discomfort, and odor. We observed synergistic increases in cough, but not in other irritant respiratory tract symptoms, with inhalation of formaldehyde and carbon. Small (<5%) synergistic decreases in FVC and FEV3were also seen. We observed no HCHO effect on FEV1; however, we did observe small (<10%) significant decreases in FEF25–75%d SGaw which may be indicative of increased airway tone. Overall, our results demonstrated synergism, but the effect is small and its clinical significance is uncertain.

ISSN:0098-4108    

DOI:10.1080/15287398909531347

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The potential of phenobarbital to interact with DNA has been studied using the sister chromatid exchange (SCE) assay in peripheral lymphocytes of nine adult male patients with epilepsy and of their matched controls. All patients were otherwise healthy individuals, treated chronically with phenobarbital in monotherapy. No statistically significant differences in SCE levels were found between the patient and control groups. Smoking was associated with increased SCE frequencies. The experiment was repeated with five available patients, using a slightly modified methodology. Although different SCE scores were obtained, the results of both tests were comparable.

ISSN:0098-4108    

DOI:10.1080/15287398909531348

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

There is evidence from animal studies that 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) impairs immune responses, with the thymus being a principal target organ. The purpose of this study was to evaluate thymic function, through measurement of thymic hormone levels, in persons exposed to TCDD. We examined thymosinalpha‐1(Thya‐1) levels in sera from a group of 94 persons who were presumed to be exposed to TCDD from living, working, or recreating in a contaminated residential area. We compared these results, along with results from in vitro and in vivo tests of immune function, with those from a group of 105 unexposed persons who were similar with regard to age, sex, and race. The exposed group had a significantly lower mean Thya‐1serum level (977.3 ± 304.1 pg/ml vs. 1148.7 ± 482.1 pg/ml,p< .01 by t‐test). We also found a statistically significant trend of decreasing Thya‐1levels with increasing number of years of residence in the TCDD‐contaminated area. However, Thya‐1levels were not associated with other measures of immune function in the TCDD‐exposed group. Thus, while the principal findings suggest that long‐term TCDD exposure may be associated with diminished secretion of Thya‐1. the lack of an association with an increased prevalence of clinically diagnosed immune suppression in these TCDD‐exposed persons makes the biologic significance of the findings unclear. Further studies are needed to more fully evaluate possible long‐term TCDD‐induced effects on the thymus and human immune function.

ISSN:0098-4108    

DOI:10.1080/15287398909531349

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Changes in body weight gain and in biochemical parameters of blood and liver were assessed in Sprague‐Dawley rats after multiple oral administration of three test doses of an Alberta crude oil (ACO). Rats treated with ACO (1.25–5 ml/kg) did not show statistically significant (p > .05) differences from control, corn‐oil treated (5 ml/kg) rats, in body weight gains, liver weight, and blood biochemical indicators of liver (alanine aminotransferase, gamma glutamyltransferase), kidney (blood urea nitrogen, creatinine), and erythrocyte (adenosine 5’ ‐triphosphate, 2,3‐diphosphoglyceric acid, reduced glutathione) cytotoxicity. Treatment with ACO, however, caused statistically significant (p < .05) and dose‐related increases from control in (1) microsomal protein and cytochrome P‐450 content, and NADPH‐cytochrome c reducíase, aryl hydrocarbon hydroxylase (AHH), and 7‐ethoxycoumarin‐O‐deethylase (7‐ECOD) activities, and (2) cytosolic glutathione transferase activity of liver. The induction of hepatic cytochrome P‐450 and xenobiotic‐metabolizing enzymes in microsomes of ACO‐treated rats was probably associated with dose‐related changes in isozymic forms of cytochrome P‐450, as evidenced by (1) appearance of a 448‐nm spectral peak in microsomes of ACO‐treated rats and (2) differences in the inhibition pattern of AHH and 7‐ECOD activities in microsomes of control and ACO‐treated rats upon treatment with metyrapone and 7,8‐benzoflavone.

ISSN:0098-4108    

DOI:10.1080/15287398909531350

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The teratogenic effects of Tordon 202c, a picloram and 2,4‐D combination formulation, are unknown. Pregnant CD‐1 mice were exposed to Tordon 202c in the drinking water at concentrations of 0.10, 0.21, and 0.42% from d 6 to 15 of gestation. Fetal growth parameters, including body weight and crown‐rump length, were reduced in a dose‐dependent manner, as was placental weight. The incidence of dead fetuses/ resorptions and malformed fetuses (especially cleft palate) was increased in the highest dosage group. A subtle indication of maternal toxicity was noted in the highest dosage group as evidenced by decreased water consumption and increased relative liver weight. The present study suggests that Tordon 202c is embryotoxic and teratogenic in CD‐1 mice when administered during organogenesis.

ISSN:0098-4108    

DOI:10.1080/15287398909531351

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Dermal absorption of the insecticide lindane was determined following topical application of ring14C‐labeled lindane to the tail of Sprague‐Dawley rats. The tail was tested as a practical alternative to the rat mid‐dorsal (back) region, and the data obtained were compared to those with rat back and with those of rhesus monkeys in our previous reports. There was no significant difference between total percentage urinary14C recovery for rats dosed on the tail with occlusive tail covers (52 ± 6.2%tv2= 2.7 d) compared to those with nonocclusive covers (55 ± 4.4%tv2= 2.9 d). Neither the total percentage urinary recovery nor the t1/2values obtained for the rat tail and rat back models differed significantly. Carbon‐14 activity was still detectable in urine samples taken after 72 d post‐treatment. However, an extensive tissue analysis failed to demonstrate14C activity persisting at 72 d, with the exception of trace levels detected in blood serum and tail tissue. Advantages of the rat tail model are highlighted.

ISSN:0098-4108    

DOI:10.1080/15287398909531352

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Technical chlordane (1,2,4,5,6,7,8,8‐octachloro‐3a, 4,7,7‐tetrahydro‐4,7‐methanoindane) is used extensively for control of certain wood‐boring insects. The present study was conducted to evaluate the inhalation toxicity of technical chlordane in rats and monkeys. Range‐finding (28‐d) and subchronic (90‐d) inhalation studies with Wistar rats, and subchronic (90‐d) inhalation studies with cynomolgus monkeys were conducted. In the range‐finding study in rats, the threshold of toxicity for technical chlordane was approximately 5.8 μg/1. Among the observations made during the course of the 90‐d study, in which technical chlordane was administered by inhalation to rats and monkeys at concentrations close to 0.1, 1.0, and 10 μg/l, the most significant were associated with alterations in the liver and were confined to rats only. However, in the rat, the effects on the liver were largely reversible during 90 d following cessation of administration of technical chlordane. The no‐effect level of chlordane inhalation in rats appears to be between 0.1 and 1.0 μg/l, while in monkeys the no‐effect level is in excess of 10 μg/l. This study demonstrated that the monkey, a species closely related to humans, can tolerate relatively high chlordane concentrations without any adverse effects.

ISSN:0098-4108    

DOI:10.1080/15287398909531353

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of oxidant exposure on the immediate airway response to immunologic challenge is controversial. We investigated the response of canine peripheral airways to antigen aerosol, 1–3 h and 24 h after a 5‐min exposure to 1 ppm ozone. In dogs that were natively sensitive toAscaris suumantigen, resistance to flow through the collateral system (Rcs) was measured using the wedged bronchoscope technique. In eight dogs, four sublobar segments of each lung were wedged: two were exposed to ozone for 5 min and two (control) received air with 5% CO2. Ozone caused a mean (±SE) increase inRcsof 75 ± 15%, which returned to baseline after 1–3 h. The increase inRcselicited by subsequent administration of antigen aerosol (25 μl, 0.27 mg protein/ml) to the ozone‐exposed segments (312.0 ± 70.6%) was attenuated by 22% compared to controls (398.9 ± 83.0% p < .05). In another series of experiments (n = 5), segments were exposed to ozone or air and challenged with antigen 24 h later and a significant attenuation (38%) of the antigen‐induced increase inRcswas detected compared to controls (178.5 ± 57.9 vs. 289.0 ± 62.2; p < .05). Cellular influx of polymorphonuclear leukocytes (PMNs) was not detected by bronchoalveolar lavage (BAL) 1–3 h after ozone, but was found after24 h (19.8 vs. 4.7% p < .01). A significant increase in PMNs was detected in exposed subepithelial tissues 1–3 h after ozone compared to unexposed tissues. Tissue PMNs were not significantly different from unexposed tissues after 24 h, but a shift toward degranulation of mast cells was detected in ozone‐exposed tissues at this time. These data suggest that theRCSresponse to antigen is attenuated 1–3 h and 24 h after acute (5 min) exposure to 1 ppm ozone, and this effect occurs independently of PMNs in the airways.

ISSN:0098-4108    

DOI:10.1080/15287398909531354

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The influence of exposure of the airways to ozone on acute allergic responsiveness has been investigated in several species. Little is known, however, about the effect of this environmental pollutant on the late asthmatic response (LAR) in animals in which it is exhibited. The purpose of this study was to evaluate this effect in the canine peripheral airways and to assess the potential role of mast cells in modulating the effect. A series of experiments on seven mongrel dogs demonstrated that the numbers of mast cells at the base of the epithelial region of small subsegmental airways exposed to 1 ppm ozone for 5 min were significantly (p< .01) increased 3 h following exposure compared to air exposed or nonexposed control airways. In a second series of experiments performed on eight additional mongrel dogs with inherent sensitivity toAscaris suumantigen, antigen aerosol was administered to the sub‐lobar segment 3 h following ozone preexposure when mast cell numbers were presumed to be increased. These experiments were performed to determine whether ozone preexposure could enhance the late‐phase response to antigen by virtue of acutely increasing the number of mast cells available to bind the antigen. Four of the eight dogs tested displayed a late‐phase response to antigen following air‐sham preexposure. In these four dogs, simultaneous ozone preexposure of a contralateral lobe completely blocked the late‐phase response to antigen. These results indicate that the consequences of a single exposure to ozone persist beyond its effects on acute antigen‐induced bronchoconstriction and extend to the complex processes involved with the late response. This attenuating effect of ozone is seen under conditions where mast‐cell numbers in the airways are increased above baseline levels.

ISSN:0098-4108    

DOI:10.1080/15287398909531355

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Because high barium concentrations (2–10 ppm) in human drinking water have been reported to be associated with elevated cardiovascular mortality, hypertension and other cardiovascular effects were sought in rats chronically exposed for 1–16 mo to drinking water containing 1, 10, or 100 ppm barium. From weaning, female Long‐Evans rats were kept in a “low contamination” environment and fed a diet low in trace metals. Their drinking water was deionized, fortified with 5 essential trace metals, and either 0,1, 10, or 100 ppm barium was added. Indirect systolic pressure of unanesthetized rats was measured in triplicate at 1, 2, 4, 8, 12, and 16 mo.

ISSN:0098-4108    

DOI:10.1080/15287398909531356

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor