Biomedical subjects
K Abdo
Publications and source records attributed to K Abdo.
Local versus systemic immunotoxicity of isobutyl nitrite following subchronic inhalation exposure of female B6C3F1 mice.
Female B6C3F1 mice were exposed to isobutyl nitrite (IBN) by inhalation at 0, 37.5, 75, or 150 ppm for 6 hr per day, 5 days per week for 15 weeks. The potential of this compound to induce immunotoxicity was assessed during the 3rd, 13th, 14th, and 15th week of exposure and after 2 weeks of recovery following the 15 weeks of exposure. Both systemic and lung immune functions were examined, including body and lymphoid organs weights, pulmonary macrophage function and host defense, expression of splenic lymphocyte cell-surface markers, natural killer cell function, mixed lymphocyte reaction, and induction of specific antibody to a T-cell-dependent antigen. There was a dose-related suppression of T-cell-dependent antibody-forming cell responses in the spleen following IBN exposure; however, other measures of T-cell and nonspecific immunity were not significantly affected. A dose-related increase of H202 production by alveolar macrophages was present after 12 but not after 68 exposures to IBN. In contrast, pulmonary host defense mechanisms against Klebsiella pneumoniae were unaffected. These results suggest that in the absence of changes in host resistance, IBN may have selective and partially reversible effects on the immune system.
Effects of gavage versus dosed feed administration on the toxicokinetics of benzyl acetate in rats and mice.
Effects of gavage versus dosed feed administration on the toxicokinetics of benzyl acetate were studied in male F344 rats and B6C3F1 mice. Benzyl acetate was rapidly hydrolysed to benzyl alcohol and then oxidized to benzoic acid. After gavage administration of benzyl acetate in corn oil at 500 mg/kg (rats) and 1000 mg/kg (mice), high benzoic acid plasma concentrations were observed. In contrast, much lower benzoic acid plasma concentrations were found after dosed feed administration at about 615 mg/kg/day for rats and about 850 mg/kg/day for mice. Results show that although the daily doses of benzyl acetate are comparable, bolus gavage administration effectively saturated the benzoic acid elimination pathway whereas dosed feed administration did not. In contrast, hippuric acid plasma concentrations were similar after both gavage and dosed feed administration due to the depletion of the glycine supply pool. Study results could explain the different toxicity and carcinogenicity responses of benzyl acetate observed in 2-yr chronic gavage and dosed feed studies.
A new case of hyperoxaluria type II.
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Survey of community adjustment of previously institutionalized developmentally disabled persons.
A survey was conducted of the community adjustment of 108 developmentally disabled (mentally retarded) persons who had spent at least three years in an institution in southeastern Ontario. On average, they had resided 3.5 years in the community, were 40 years of age, with a mental age of five years and a median IQ of 41, and most had one or more moderate to severe physical disabilities. During their most recent year living in the community it was found that their daily living skills remained unchanged compared with their skill level in the year prior to community placement. As well, the community staff rated them as average in level of performance and amount of supervision required compared with others of similar ability. About one third were found to have a moderate to severe behavioural/psychiatric problem with aggressive disruptive behaviour being most frequent. Of the two-thirds capable of being interviewed, over three-quarters expressed satisfaction with their present living, work, education and recreation environment and had no desire to return to the institution. Most had few if any meaningful relationships with non developmentally disabled persons other than caregivers. Support agency staff and psychiatric consultants identified additional service needs for those with behavioural/psychiatric problems who may be placed in the community.
Prechronic inhalation toxicity studies of 2-mercaptobenzimidazole (2-MBI) in F344/N rats.
2-Mercaptobenzimidazole (2-MBI), used in rubber processing, is a suspect carcinogen structurally related to ethylene thiourea. The inhalation toxicity of 2-MBI was evaluated in male and female F344/N rats exposed 6 hr/day, 5 days/week to respirable aerosols generated by spray atomization of aqueous suspensions of the 2-MBI powder and subsequent drying of the resulting aerosols. Twelve exposures at target concentrations of 0, 6.3, 12.5, 25.0, 50.0, or 100 mg/m3 of 2-MBI produced a dose-related reduction in body weight gains, thyroid follicular cell hyperplasia, adrenal cortex fatty change, and pituitary atrophy. Sub-chronic exposures were conducted at target concentrations of 0, 3.1, 6.2, 12.5, 25.0, and 50.0 mg/m3 of 2-MBI. Rats at greater than or equal to 25 mg/m3 displayed hunched posture, hypoactivity, and reduced body weight gain, with compound related mortality at the highest exposure level. Anemia; increased SGPT, SGOT, alkaline phosphatase, sorbitol dehydrogenase, BUN, and cholesterol; and reduced free fatty acid were seen in rats at greater than or equal to 25 mg/m3. Increased thyroid weight and thyroid follicular cell hyperplasia were noted in both sexes at greater than or equal to 6.2 mg/m3, with reduced triiodothyronine and thyroxine levels in both sexes at greater than or equal to 12.5 mg/m3. Thyroid follicular cell hyperplasia was also seen in rats at 3.1 mg/m3. Thymus weights were significantly reduced in both sexes at all exposure levels with liver weight increases at greater than or equal to 6.2 mg/m3. Exposure-related histopathologic changes included pituitary cytoplasmic vacuolization, adrenal cortex necrosis, lymphoid depletion, thymic atrophy, liver cell hypertrophy, renal mineralization and tubular atrophy, and hypocellularity of the bone marrow.