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Biomedical subjects

B N Gupta

Publications and source records attributed to B N Gupta.

At least 109 records · Page 6Linked to original sources
PubMed1981

The influence of malnutrition on the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in rats.

A single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (20 or 40 microgram/kg body wt) administered to rats resulted in reduced body weight gain, water intake, degenerative changes in the liver and involution of the thymus. Although a restricted diet alone caused thymic involutions it was shown that TCDD at 10 or 20 microgram/kg body wt accentuated this atrophy. Microscopically, a marked atrophy of the thymus and swelling and necrosis of the liver were found in the malnourished animals. The effects of TCDD were also tested in rats fed either 3.5%, 26% or 55% protein. There was no clear relation between the protein level and the influence of TCDD on the thymus. However, the effect of TCDD on body weight and the liver was more severe in rats given low protein diet. These effects were not reversed by high protein diet. Since it is unlikely that the influence of TCDD on the thymus is related to malnutrition, other mechanisms, such as depletion of energy reserves, a direct effect of TCDD on the thymus or a mediation by the hepatotoxic action may be involved.

Animals↗
PubMed1981

The influence of high and low sodium intake on blood volume in the dog.

Plasma volume and blood volume were measured using T-1824 in two groups of dogs which were kept on a diet differing only in its content of sodium chloride for periods exceeding six weeks. The group on low sodium intake received 0.55 mmol Na.g-1.day-1 and the group on high sodium intake received 12.4 mmol Na.g-1.day-1. Both plasma and blood volumes were distinctly greater in the group on high sodium intake than those in the group on low sodium intake, and there was no differences in the haematocrit between the two groups of dogs. It is concluded that a greater plasma volume and red cell volume resulted from high sodium intake than from low sodium intake.

Animals↗
PubMed1980

Role of the endocrine system in the action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the thymus.

Several experiments were conducted to study the involvement of the adrenal and the pituitary gland in the acute toxic effects of TCDD. Adrenalectomized or hypophysectomized rats were treated with a single oral dose of 10 or 20 microgram of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg body weight. The reduced growth rate, the hepatotoxic effects and thymic involution induced by TCDD were not prevented by the adrenalectomy. The pituitary gland did not appear to be involved in causing thymic involution. In fact, the thymic effects of TCDD intoxication were even somewhat increased in hypophysectomized rats. Treatment with growth hormone failed to prevent thymic involution or the influence of TCDD on the liver.

Adrenal Cortex Hormones↗
PubMed1980

A comparison of the effects of paraquat and diquat on lung compliance, lung volumes and single breath diffusing capacity in the rat.

Paraquat intoxication in its initial stage is characterized histologically in the lungs by atelectasis, hyaline membrane formation, alveolar edema and vascular hemorrhage often into the interstitium or air spaces. Information on the functional modification of paraquat-damaged lungs has been lacking. We evaluated lung volumes, single breath diffusing capacity of the lungs for carbon monoxide (DLCO) and static lung compliance (Cst(L)) in rats treated with paraquat or diquat. Measurements were made 12, 24, 48, and 72 h after treatment. Paraquat by intratracheal (i.t.) instillation 0.5 mg/kg or by intraperitoneal injection (i.p.) 27 mg/kg significantly decreased (P less than 0.01) the body weight, total lung capacity (TLC), functional residual capacity (FRC), vital capacity (VC), residual volume (RV), DLCO, apparent alveolar volume (VA) and Cst(L). At a lower dose level (13.5 mg/kg), the effects of paraquat peaked at about 24 h following treatment, causing a significantly decreased (P less than 0.01) VC and TLC. Diquat i.t. or i.p. had little effect on the lungs. However, diquat i.p. decreased body weight (P less than 0.01) and caused a slight increase (P less than 0.05) in VC. The data obtained are consistent with the known pathological changes seen in paraquat-damaged lungs in that, by both routes, paraquat caused severe lung damage associated with decreased elasticity of the lungs and thorax, destruction of gas exchanging alveolar surfaces, and edema. These changes were detected reliably by lung function measurements.

Animals↗
PubMed1979

Cold-sensitive afferents from the abdomen.

In cats afferent impulses from splanchnic and vagus nerve preparations were studied. In each splanchnic nerve serving the stomach or the adjacent part of the duodenum, cold-sensitive afferents could be recorded. There were also numerous mechanosensitive fibers originating from stomach, intestine, mesentery and the region of blood vessels. No thermal afferents were found in the vagus nerve. The cardiovascular and respiratory myelinated afferents were insensitive to thermal stimuli.

Abdomen↗
PubMed1979

Biochemical effects of pure isomers of hexachlorobiphenyl: fatty livers and cell structure.

The effects of a single oral dose (50 mg/kg body wt.) of 3,4,5,3',4',5'-hexachlorobiphenyl (HCB), 2,4,5,2',4',5'-HCB or 2,3,5,2',3',5'-HCB for a period of 72 h have been studied in the male rat. Only 3,4,5,3',4',5'-HCB caused necrosis of thymocytes. 3,4,5,3',4',5'-HCB caused marked pathological changes in the liver with less marked effects being caused by 2,4,5,2',4',5'-HCB and 2,3,5,2',3',5'-HCB. Total lipid content was increased by all the isomers studied, but 3,4,5,3',4',5'-HCB had more pronounced effect on total lipid content. Lipid accumulation was pericentral in the livers obtained from rats treated with 3,4,5,3',4',5'-HCB, but midzonal in the liver obtained from the rats treated with the other two isomers. Analysis of various lipid fractions showed that triacylglycerols were increased seven-fold only by 3,4,5,3',4',5'-HCB, while phospholipids were increased slightly by 2,4,5,2',4',5'-HCB or 2,3,5,2',3',5'-HCB. Only 3,4,5,3',4',5'-HCB increased the level of total and esterified cholesterol. These results show that the fatty livers caused by 3,4,5,3',4',5'-HCB were qualitatively and quantitatively different from those caused by the other two isomers at the same dose. For the first time a hexachlorobiphenyl unchlorinated in the para position, 2,3,5,2',3',5'-HCB has been shown to be a specific inducer of cytochrome P-450. The effects of 2,3,5,2',3',5'-HCB on cell structure and phospholipid content were quantitatively similar to those caused by 2,4,5,2',4',5'-HCB. Thus, chlorination at para (4,4') positions in chlorobiphenyls is not necessarily required for biological activity. It is hypothesized that net stereoelectronic properties of the isomers or resistance to metabolism may be the underlying factor in determining structure-activity relationships.

Animals↗
PubMed1979

The intrasanguineous host-mediated assay procedure distribution and retention of yeast in the mouse.

A study of the factors that could affect a method to detect mutations in cells recovered from different organs after intravenous injection in mice, was performed by using the D4 strain of Saccharomyces cerevisiae. The recovery of the yeast cells 5 min to 3 days after injection in the host animal was investigated. The circulation, distribution and localization of the cells were determined, and histopathologic analysis was performed in order to detect possible interactions between the mice and the microorganisms. We found that the yeast cells were trapped primarily in the capillaries of the organs; 3 days after injection no cells were found outside of the tissue-blood vessels. The spontaneous gene-conversion frequency of the yeast cells recovered at different times after injection was increased, but this increase was not time-dependent.

Animals↗
PubMed1979

Toxicologic assessments of a commercial polybrominated biphenyl mixture in the rat.

A polybrominated biphenyl fire retardant (Firemaster FF-1) was responsible for the widespread environmental contamination and animal losses in Michigan during 1973 and 1974. In Fischer 344/N rats orally given 30,100,300, and 1,000 mg/kg (5 days/week, 22 total doses) for 4.5 weeks and observed for 90 days after the start of treatment, the LD50 was determined to be 65 mg/kg/day (total 1.43 g/kg) for the female rat and 149 mg/kg/day (total 3.28 g/kg) for the male. All female rats given the dosage of 100 mg/kg/day (22 doses, total 2.20 g/kg) died between 41 and 53 days after the start of treatment, whereas 38% of the males died between 50 and 73 days. Pathologic changes in treated rats were large liver, accentuation of the hepatic lobular markings, and atrophy of thymus and spleen. Microscopically, hepatic changes were characterized by congestion, fatty metamorphosis, and multifocal liquefactive necrosis. Male rats given 100 mg/kg/day and dying after 90 days had subacute to chronic hepatitis with marked focal proliferation of bile ducts. Exposure to Firemaster FF-1 may produce atypical liver nodules in the rat as early as 6 months after they were first given the preparation. Marked hepatotoxic effect persisted in surviving rats when examined after 6 months.

Administration, Oral↗
PubMed1979

Toxicological studies of ammonium sulfamate in rat after repeated oral administration.

A 90-day study involving administration of O (group 1), 100 (group 2), 250 (group 3) and 500 mg/kg (group 4) of ammonium sulfamate to rats 6 days a week was carried out. No adverse effect was observed in respect of appearance, behaviour or survival of animals. No significant difference in the body weights of rats was observed except in case of adult rats (group 4) where the body weight was significantly less than the controls after the end of 60 days. In all the groups food intake gradually reduced whereas water intake increased as the experiment proceeded. No significant change in relative organ weights were noticed in all groups of rats. Haematological examination conducted at 30, 60 and 90 days revealed non-significant increase in the neutrophils in the adults and male weanling rats (group 4) after 90 days. In the histological examination, organs in all the groups of animals appeared normal except that the liver of 1 rat in adults (group 4) showed slight fatty degenerative changes after 90 days.

Administration, Oral↗
PubMed1978

Pulmonary aspergilloma in a rat.

Small grayish white nodules were observed in the lungs of a young female rat. Microscopically, the pulmonary nodules were composed of granulomatous tissue and septate branching mycelia. The organism was identified as Aspergillus sp by direct fluorescent antibody technique.

Animals↗