摘要:

Autopsy kidney specimens from 24 children with kwashiorkor and 21 with other miscellaneous diseases, at the Obafemi Awolowo Teaching Hospital Complex, Ile-Ife, Nigeria, were analyzed for the presence of aflatoxins using high-performance liquid chromatography. Aflatoxins were detected in 14 children who died of kwashiorkor and in 13 of those who died from miscellaneous diseases. Aflatoxicol was detected in 10 specimens, 7 of which had severe gastroenteritis. Seven kidney specimens demonstrated the presence of more than one type of aflatoxin; four of these were kidneys of patients with kwashiorkor and the remaining three died from renal failure. No difference was found between the frequency of detection, type of aflatoxin detected, or mean concentrations of total aflatoxins in the kidney specimens of the kwashiorkor children when compared to the kidney specimens of children who died from miscellaneous diseases. These findings demonstrate that aflatoxins can be detected in the kidneys of children exposed to aflatoxins.

ISSN:1528-7394    

DOI:10.1080/009841098158368

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

The determination of chromosome aberrations (CA) in Chinese hamster lung fibroblast (CHL) cells was compared with that in normal human bronchial epithelial (BEAS-2B) cells, which upon adenovirus infection were reported to possess carcinogen metabolizing capacities similar to polycyclic aromatic hydrocarbons. CHL and BEAS-2B cells were treated with increasing concentrations of benzo\[a]pyrene ( BaP) or N -nitrosodiethylamine (NDEA) . In BEAS-2B cells, BaP, at a concentration of 50 mug/ml, produced a significant increase in the CA frequency, while NDEA did not markedly alter the number of aberrations in the absence of S9 mixture. The CHL cells exposed to BaP and NDEA in the presence of S9 mixture responded as anticipated with a 30% and 14% frequency of CA observed in the BaP (50 mug/ ml) and NDEA (1000 mug/ ml) treated cells, respectively. The results of this study show that the CA assay using human cell line with intrinsic metabolic activation system, such as BEAS-2B cells, may be a useful model for predicting human clastogens and carcinogens.

ISSN:1528-7394    

DOI:10.1080/009841098158377

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

2,3,7,8-Tetrachlorodibenzo- p -dioxin ( TCDD) alters the turnover of vitamin A in the body and inhibits the normal hepatic accumulation of dietary vitamin A. Vitamin A is absorbed in the small intestine, where it is incorporated into chylomicrons as retinyl esters for release into the lymph and further distributed via blood to the liver for storage. The aim of the present study was to investigate if the decreased hepatic vitamin A levels in TCDD-exposed rats could be due to impaired intestinal absorption of vitamin A via lymph. Male Sprague-Dawley rats were given a single oral dose of TCDD ( 10 mug/kg). Five days after administration, the main intestinal lymph duct of the rats was cannulated. After a 24-h recovery from surgery, the rats were each given a single dose of [3H]retinol in corn oil via gavage and the lymph was collected for 24 h. The cumulative radiolabel recovered in the intestinal lymph was significantly lower in TCDD-treated than in control rats during the first 6 h of absorption. However, no significant differences in radiolabel recovered in lymph were seen when looking at the entire 24-h collection period. In the intestinal mucosa, retinol esterification catalyzed by the enzyme lecithin:retinol acyl transferase ( LRAT) or acyl coenzyme A (CoA):retinol transferase (ARAT) was not statistically different between the groups. However, mucosal retinyl palmitate levels were significantly increased in TCDD-treated rats. In conclusion, a small and transient reduction was found of the uptake of vitamin A into the lymph of TCDD-treated rats. It is obvious that this finding cannot explain the TCDD-induced decrease in hepatic vitamin A levels in the rat. Rather, a combination of inhibited retinol esterification in hepatic stellate cells, increased release of endogenous vitamin A, and increased hepatic catabolism of retinoids could explain the effect of TCDD on liver retinoid levels.

ISSN:1528-7394    

DOI:10.1080/009841098158386

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Isoamyl nitrite (IAN) is a member of the family of volatile organic nitrites that exert vasodilatory effects and have recently exhibited a considerable potential for inhalation abuse. In an effort to provide mechanistic insight into the neurotoxic effects and abuse potential of these agents, the present study was designed to evaluate the acute effects of IAN on the hypothalamo-pituitary-adrenal (HPA) axis. Attempts were also made to correlate the neuroendocrine effects of IAN with its pharmacokinetic profile. Male Sprague-Dawley rats were exposed to 600 or 1200 ppm IAN by inhalation for 10 or 30 min. Following exposure, adrenocorticotropic hormone (ACTH) and corticosterone in plasma and corticotropin-releasing factor ( CRF) in three brain regions (hypothalamus, hippocampus, and frontal cortex) were determined by radioimmunoassay. Levels of IAN in the three brain regions as well as in blood were measured by gas chromatography to determine the target tissue concentrations responsible for neuroendocrine changes. Uptake of IAN into blood and all brain regions was very rapid, as stable concentrations were achieved within 10 min of exposure and maintained for 30 min of continuous inhalation. Plasma corticosterone decreased significantly after 10 min inhalation of both IAN doses, and returned to control levels after 30 min. Moreover, plasma ACTH was significantly increased by 10 and 30 min of exposure to 600 and 1200 ppm IAN, while hypothalamic CRF increased significantly after 30 min of exposure to the 600 ppm dose. These latter findings suggest activation of the hypothalamus and pituitary due to a reduction in negative feedback resulting from the initial decrease in corticosterone. Although plasma ACTH was greatly increased after 30 min, plasma corticosterone levels were unchanged, indicating that IAN primarily acts to inhibit the synthesis or secretion of adrenal steroids and that activation of the HPA axis is not involved in the behavioral manifestations of IAN inhalation. These compensatory effects of HPA axis regulation, and possibly the vasodilatory properties of IAN, also likely precluded the establishment of definitive relationships between observed changes in hormone levels and blood or regional brain concentrations of the inhalant.

ISSN:1528-7394    

DOI:10.1080/009841098158395

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Since tumor growth factor beta (TGF- ) and its receptor are ubiquitously expressed and because latent TGF- cannot bind to the cell surface receptor, the ability of a cell to activate latent TGF- upon secretion represents an important regulatory mechanism of TGF- action. In vivo, the protease plasm in is considered to be one of the main enzymes operative in the proteolytic cleavage of the latency-associated peptide moiety from TGF- , which converts it into the biologically active form. The TGF- response was characterized in alveolar macrophages during pulmonary inflammation (d 3) and fibrosis (d 120) induced by a single intratracheal instillation of silica particles ( 5 mg/ mouse). To appreciate the role of urokinase-type plasminogen activator (uPA) in the activation of TGF- , the production of total, active and latent TGF- by explanted alveolar macrophages was compared in uPA-deficient (uPA-/-) mice and their normal counterparts (uPA+/ +) . At d 3 and 120 after silica treatment, a significant increase in cell-associated PA activity was found in uPA+/ + mice compared to that of saline controls. As expected, this response was almost totally absent in uPA-/- mice. Alveolar macrophages from uPA+/ + controls were found to release TGF- mainly expressed in a biologically active form. In response to silica treatment, inflammatory cells were found to upregulate, especially at the fibrotic stage, their secretion of total and bioactive TGF- . No significant difference was found between uPA-/- and uPA+/ + silica-treated animals for the expression of total, active, or latent TGF- . Although it has previously been reported that macrophage surface activation of TGF- is dependent on both plasmin generation and uPA cell surface receptor, no evidence was found to support this hypothesis in the present study.

ISSN:1528-7394    

DOI:10.1080/009841098158403

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Interaction of tributyltin ( TBT) with 3,3',4,4',5-pentachlorobiphenyl (PCB-126)-induced ethoxyresorufin O -deethylase ( EROD) activity was examined in vitro using H4IIE rat hepatoma cells. H4IIE cells were exposed to TBT and PCB-126, individually or in combination, at different concentrations. TBT was cytotoxic at concentrations greater than 98 n M . PCB-126 was not cytotoxic in the concentration range of 49 to 3140 p M . At concentrations greater than 49 n M , PCB-126 enhanced the cytotoxicity of TBT in the 24-98 n M range. In the absence of inducers of EROD activity, TBT significantly inhibited constitutive EROD activity in H4IIE cells in a concentration-dependent manner. EROD activity in H4IIE cells was significantly increased by exposure to PCB-126 alone. This effect was potentiated by coexposure to low, noncytotoxic concentrations of TBT. The induction of cytochrome P-4501A (CYP1A) activity in the presence of both an inducer (PCB-126) and low concentrations of an inhibitor (TBT) indicates that TBT does not interfere with the Ah receptor binding, but acts at the transcriptional level. Potentiation of EROD activity and cytotoxicity as a consequence of coexposure to PCB-126 and TBT is of considerable toxicological significance, given their coaccumulation in a variety of marine organisms.

ISSN:1528-7394    

DOI:10.1080/009841098158412

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Removal efficiency of chloroform from tap water by rice bran was investigated. The adsorption rate by rice bran was similar to activated carbon. The amount of chloroform adsorbed was plotted against the equilibrium concentration of chloroform in solution on a logarithmic scale. A linear relationship was obtained, indicating that the adsorption reaction was a Freundlich type. The adsorption of chloroform by rice bran was observed in the range of pH 1-11. Chloroform was successfully removed from tap water with average removal efficiency of 70% after 60 min when rice bran was applied to tap water that contained 0.0064 mg/ L chloroform.

ISSN:1528-7394    

DOI:10.1080/009841098158421

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor