Induction of hyperplasia in the bladder epithelium of rats by a dietary excess of acid or base: Implications for toxicity/carcinogenicity testing

In previous studies we observed an increased incidence of hyperplasia in the epithelium of the urinary bladder of rats fed cereal-based stock diet supplemented with 6% monosodium glutamate (MSG) for 3 months. Hyperplasia was not enhanced, however, when 6% MSG was fed in a purified casein diet. Further studies have been conducted to identify the...

Nasal tumours in rats after short-term exposure to a cytotoxic concentration of formaldehyde

Male Wistar rats were exposed to 0, 10 or 20 ppm formaldehyde vapour for 4, 8 or 13 weeks (6 h/day; 5 days/week), and were then observed for periods up to 126 weeks. Transient growth retardation occurred in both test groups. Death rate was not noticeably affected by formaldehyde. Despite recovery periods of at most 126 weeks, the nasal...

Pulmonary response of hamsters to fibrous glass. - Clearance and morphology after a single intratracheal instillation

In a one-year serial sacrifice study 10 mg glass fibres (length, 95% ?? 20 ??m, 89% ?? 12 ??m, 58% ?? 5 ??m and 25% ?? 2 ??m; diameter, 88% ?? 1.0 ??m, 60% ?? 0.5 ??m and 31% ??0.25 ??m) suspended in 0.2 ml saline solution were administered to Syrian golden hamsters by a single intratracheal instillation to determine the clearance of the glass...

Chronic (89-week) feeding study with hydroxypropyl distarch phosphate, starch acetate, lactose and sodium alginate in mice

Respiratory tract tumors in hamsters after severe focal injury to the trachea and intratracheal instillation of benzo[a]pyrene

Two groups of male and female Syrian golden hamsters, of which the trachea was severely injured by electrocoagulation, received 6 weekly intratracheal instillations of benzo[a]pyrene (BaP) + ferric oxide in saline or saline alone. Two comparable groups of hamsters were similarly treated but had an undamaged trachea. The experiment was terminated...

Pulmonary response of hamsters to fibrous glass: Chronic effects of repeated intratracheal instillation with or without benzo[a]pyrene

Syrian golden hamsters were given intratracheal instillations of glass fibres with or without benzo[a]pyrene suspended in saline, once a fortnight for 52 weeks. The experiment was terminated at week 85. 'Silicotic granulomas' consisting of tightly packed, iron-positive macrophages filled with glass fibres and surrounded by a layer of alveolar...

Restoration of the hamster tracheal wall following injury by electrocoagulation

The trachea of Syrian golden hamsters was injured by electrocoagulation. The lesions induced as well as the repair process were studied by light and scanning electron microscopy. The changes observed were considered to create the proper conditions for studying the significance of severe focal damage to the respiratory tract for the formation of...

Electrocoagulation as a method to induce local lesions in the tracheal wall of Syrian hamsters

Absence of an effect of lead acetate on sperm morphology, sister chromatid exchanges or on micronuclei formation in rabbits

The influence of lead on sperm morphology, sister chromatid exchanges or on micronuclei formation was studied on male rabbits after exposure to doses of 0, 0.25, and 0.50 mg lead acetate/kg body weight subcutaneously injected three times a week during 14 weeks, each on a group of five rabbits. At the end of exposure phase the lead in blood...

Repeated exposure to butenolide vapour: Subacute study in Syrian golden hamsters

The subacute inhalation toxicity of butenolide was examined in hamsters by repeated exposure of 4 groups of 10 males and 10 females to butenolide vapour at concentrations of 0, 5.4, 25 and 130 ppm respectively (6 h/day, 5 days/week) for a period of 13 weeks. The effects found at 130 ppm included eye irritation, salivation, nasal discharge,...

Repeated exposure to acrolein vapour: Subacute studies in hamsters, rats and rabbits

The subacute inhalation toxicity of acrolein was examined in 4 groups of 20 hamsters, 12 rats and 4 rabbits each, exposed repeatedly to acrolein vapour at concentrations of 0, 0.4, 1.4 and 4.9 ppm (6 hr/day, 5 days/week) for a 13-week period. The most important effects found at the highest level included mortality in rats, ocular and nasal...

Short term inhalation toxicity studies with peroxyacetyl nitrate in rats

The inhalation toxicity of peroxyacetyl nitrate (PAN) was examined in acute (single exposure), subacute (4-wk repeated exposure) and subchronic (13-wk repeated exposure) studies in rats. The 4-hr LC50 was found to be 95 ppm. In the 4-wk study rats were exposed to 0, 0.9, 4.1 or 11.8 ppm PAN vapor for 6 hr/day, 5 days/wk. Exposure to 11.8 ppm...