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Biomedical subjects

K S Khera

Publications and source records attributed to K S Khera.

At least 37 records · Page 2Linked to original sources
PubMed1984

Vomitoxin (4-deoxynivalenol): effects on reproduction of mice and rats.

Weanling male and female mice (F0) were fed daily diets containing 4-deoxynivalenol (DON) at concentrations that resulted in a dose of 0 or 2.0 mg/kg body wt in Experiment I and 0, 0.375, 0.75, or 1.5 mg/kg body wt in Experiment II. The test diets were continuously fed to the F0 parents and their progeny for the entire duration of these two experiments, which were similar in design. After 30 days of dietary feeding, the mice were allowed to mate within experimental groups for a maximum of three 5-day trials. Females found to have mated successfully were allowed to litter normally. The F1a progeny from 10 dams of each control and 1.5-mg DON/kg groups were cross-fostered at birth, whereas all of the remaining F1a progeny were reared by their natural dams. The progeny were examined until 21 days of age and discarded. The F0 mice were rebred. The females bred to produce the F1b litters were killed on Day 19 of gestation and their fetuses were examined for gross, visceral, and skeletal malformations. Reductions were observed in feed and water intakes and body weight of F0 male and female mice, the number of live pups and postnatal survivors, postnatal body weight of F1a progeny, number of live fetuses, and mean fetal weight of F1b fetuses. No adverse effects on fertility of F0 male and female mice and no major malformations in F1b were found. Cross-fostering offspring between control dams and 1.5-mg DON/kg-treated dams revealed that both postnatal survival and body weight were adversely affected by prenatal exposure as well as by a combined pre- and postnatal exposure. Male and female Sprague-Dawley rats were fed diets containing DON so as to deliver daily doses of 0.25, 0.5, or 1.0 mg/kg body wt. After 6 weeks of feeding, the rats were bred within groups and the males were then discarded. The mated females, maintained on their respective diets for the entire period of pregnancy, were killed on the last day of pregnancy and fetuses evaluated for effects on prenatal development. Except for dilation of renal pelvis and urinary bladder, the significance of which remains undetermined, no other adverse effect was observed.

Abnormalities, Drug-Induced↗
PubMed1984

Ethylenethiourea-induced hindpaw deformities in mice and effects of metabolic modifiers on their occurrence.

Time-mated Swiss-Webster mice were pretreated in separate experiments with phenobarbital (60 mg/kg X d sc on d 7-10 of pregnancy), SKF-525A (40 mg/kg ip on d 12 of pregnancy) or 3-methylcholanthrene (20 mg/kg X d on d 10-12 of pregnancy). On the d 12 of pregnancy (1 h after SKF-525A or 3-methylcholanthrene treatment), one group each of pretreated mice was given a single oral dose of 1600, 2000, or 2400 mg/kg of ethylenethiourea (ETU) as a 5% concentrate in a 1.5% aqueous gelatin solution, which as a vehicle was given to other pretreated groups. The respective volume doses were 3.2, 4.0, or 4.8 ml/100 g body weight with the controls given 4.8 ml/100 g body weight of vehicle alone. Maternal toxicity was observed in all groups given ETU, whether pretreated with metabolic modifiers or not. In the three experiments, treatment with ETU alone reduced fetal weight by 15% at 2400 mg/kg and 8% with the remaining 2 doses, and increased the incidence of resorptions (19-62% with the 2400 mg/kg dose, 8-59% at 2000 mg/kg, and 7-32% at the 1600 mg/kg dose). The significant defects with incidence ranges in three experiments were: hindpaw ectrodactyly, 2-6% at 1600 mg/kg, 4-20% at 2000, and 20-29% at 2400 mg/kg; and hindpaw syndactyle, 3% at 16 mg/kg, 6-14% at 2000, and 2-12% at 2400 mg/kg doses. Minor incidences of cleft palate and hindpaw polydactyly were also observed. Phenobarbital pretreatment did not change the ETU-induced maternal or fetal effects. SKF-525A enhanced the resorptions and reduced the litter-size but had no effect on fetal malformations. The 3-methylcholanthrene pretreatment reduced the ETU-induced incidences of hindpaw ectrodactyly, hindpaw syndactyly, and cleft palate at the 2000 and 2400 mg/kg doses. Previous studies with rats and hamsters revealed that SKF-525A enhanced the ETU-induced fetal malformations but phenobarbital and 3-methyl-cholanthrene had no effect in these two species.

Abnormalities, Drug-Induced↗
PubMed1982

Reduction of teratogenic effects of ethylenethiourea in rats by interaction with sodium nitrite in vivo.

Nitrites are present in a wide variety of foods and their daily intake in man has been estimated at 1.5 mg. Ethylenethiourea (ETU), a major food contaminant resulting from degradation of ethylenebisdithiocarbamate fungicides, is a potent rat teratogen. The co-administration of ETU (60 or 40 mg/kg) and NaNO2 (80 mg/kg) to rats by gavage on day 15 of gestation resulted in a higher survival of progeny than occurred with the corresponding dose of ETU alone. In a second study, ETU (60 mg/kg) and NaNO2 (80, 100 or 120 mg/kg) were administered, either individually or in combination, as a single dose on day 13 of gestation. Administered alone, NaNO2 did not produce any teratogenic response in full-term foetuses, whereas ETU produced a high incidence of various anomalies. However, the combined dosing resulted in the elimination of almost all the anomalies. The reducing effect of NaNO2 on ETU-induced malformations was reversed when the animals were pretreated with 200 mg ascorbic acid/kg or 360 mg sodium ascorbate/kg. Since both of these are well-known inhibitors of N-nitrosation reactions, it was presumed that the simultaneous oral dosing of ETU and NaNO2 resulted in the formation of N-nitrosoethylenethiourea.

Abnormalities, Drug-Induced↗
PubMed1982

Teratogenicity study on pyrethrum and rotenone (natural origin) and ronnel in pregnant rats.

Insecticidal formulations in the form of dusts or aerosols containing rotenone from the root of Derris elliptica and pyrethrum from the flower of Chrysanthemum cinerariaefolium are commonly used in homes and gardens. Ronnel (fenchlorphos), a systemic insecticide, is used to control house flies and, upon oral treatment, ectoparasites of cattle. These insecticides are extensively used and their teratologic potential has not been fully investigated. Technical grades of rotenone at 0, 2.5, 5, or 10 mg/kg, pyrethrum at 0, 50, 100, or 150 mg/kg (rotenone and pyrethrum were of natural origin) and ronnel at 0, 400, 600 or 800 mg/kg were tested. Each of these was suspended in corn oil and administered orally in single daily doses on d 6-15 of pregnancy to Wistar rats. The dams were killed on the last day of pregnancy, and all fetuses were evaluated following routine teratologic methods. Rotenone was associated with an increased number of nonpregnant rats and resorptions, at a dose of 10 mg/kg; reductions in maternal body weight gain, fetal weight, and skeletal ossification, together with an increased incidence of extra rib, were found at 5 and 10 mg/kg; but no significant effects were found at 2.5 mg/kg. Increases in the incidence of resorptions in pyrethrum-treated groups and of extra rib in ronnel-treated groups were also observed.

Animals↗
PubMed1981

Effects of pretreatment with SKF-525A, N-Methyl-2-thioimidazole, sodium phenobarbital, or methyl cholanthrene on ethylenethiourea-induced teratogenicity in rats.

SKF-525A (SKF), a well known inhibitor of P450 function, and N-methyl-2 thioimidazole (MMI), an antithyroid drug resembling ethylenethiourea, were tested at the respective dosages of 40 Mg/kg ip and 200 mg/kg po, for their individual or combined effect on the teratogenicity on an oral dose of 60 mg/kg ethylenethiourea (ETU). All chemicals were dissolved in distilled water and administered to rats on the 13th day of pregnancy. MMI and ETU were dosed simultaneously, one hour after dosing with SKF. Control groups were given equivalent doses of ETU (positive control), SKF, MMI, or SKF+MMI. Term fetuses were evaluated for anomalies according to the established procedures. No teratogenic activity was attributed to treatments with SKF, or MMI, of their combination. However, in the remaining test groups, MMI+SKF+ETU+, or SKF+ETU, the type, incidence, and intensity of anomalies, compared to the group given only ETU, were markedly increased and were similar to those previously reported to occur at 120 mg/kg or higher doses of ETU. Pretreatment with either 40, 60, or 80 mg/kg of sodium phenobarbital injected once or twice a day on days 9-12 of pregnancy, or 20 mg/kg/day of methylcholanthrene on days 11-13 of pregnancy, failed to alter significantly the teratogenicity of a subsequent dose of 60 mg/kg of ETU given orally on the 13th day of pregnancy.

Animals↗
PubMed1979

A teratogenicity study on hydroxyurea and diphenylhydantoin in cats.

Hydroxyurea, an antitumor drug and known teratogen in rat, miniature swine and dog, and diphenylhydantoin, a teratogen in mouse and rat, were assessed for teratogenic effects in cat. Pregnancies were induced, by synchronizing gonadotropin-stimulated estrus and ovulation with natural copulations. Hydroxyurea at 50 or 100 mg/kg, and sodium diphenylhydantoin at 1 or 2 mg/kg dosages, were administered orally in single daily doses from gestation days 10-22. Appropriate controls given empty capsules, were included for each drug. Cats were necropsied on gestation day 43. Fetuses were examined for external, visceral and skeletal malformations. Hydroxyurea at 50 mg/kg dose produced a low teratogenic activity and at 100 mg/kg a high incidence of non-pregnancy and resorptions with, consequently, fewer live fetuses. Diphenylhydantoin gave no clear evidence of teratogenicity at any test dose but was embryolethal at the maternally toxic dose of 2 mg/kg. So far, studies conducted suggest that the cat is a useful species for screening drugs and chemicals for their teratogenic potential.

Abnormalities, Drug-Induced↗
PubMed1979

Photomirex: a teratogenicity and tissue distribution study in the rabbit.

Adult New Zealand white does were intubated orally with single daily doses of 0, 5, or 10 mg of photomirex (8-monohydromirex) per kg body weight from the 6th through to the 18th day of gestation. Pregnancies were interrupted at term by cesarian section and fetuses removed and evaluated by following routine teratologic methods. Both maternal and fetal tissues were analyzed for residues of photomirex. None of the treated does showed any sign of toxicity. Except for a significant reduction in the mean fetal weight of the 10 mg/kg group all other parameters which evaluated fetal survival and fetal development were within the control range. Photomirex was found in all tissues examined. In the doe, the highest levels were found in fat followed by liver, kidney, spleen, heart, brain and blood. Photomirex was readily transferred across the placenta and accumulated in the fetus. However, in the fetus the highest levels were found in the heart, followed by liver, brain and blood. There were no teratogenic effects at the doses used in this study.

Animals↗
PubMed1979

Teratologic assessment of maleic hydrazide and daminozide, and formulations of ethoxyquin, thiabendazole and naled in rats.

Teratogenicity studies were conducted in rats treated orally from days 6-15 of gestation with single daily doses of 400-1600 mg/kg of maleic hydrazide, 300-1000 mg/kg daminozide, 125-500 mg/kg ethoxyquin or thiabendazole, or 25-100 mg/kg naled. Dams were killed on the 22nd day of gestation, and fetuses were evaluated by routine teratologic methods. No adverse effect was related to any treatment other than an increased incidence of anomalous fetuses at the highest dose (500 mg/kg) of thiabendazole.

Animals↗
PubMed1978

Dimethadione-induced fetotoxicity in rats.

The fetotoxic potential of dimethadione was studied in rats given single daily oral dosages of 0, 54, 433 or 541 mg/kg on days 1--21 or 6--15 of gestation. No maternal toxicity was observed following treatment on days 6--15. When administered from days 1 to 21 only the highest dose (541 mg/kg) produced a significant reduction in maternal body weight gain. Dimethadione caused a dose-related decrease in fetal weight and an increased incidence of umbilical hernia, ecchymoses and subcutaneous edema. There were also increased incidences of non-specific skeleton defects which consisted of unilateral or bilateral wavy ribs, additional ribs (14th rib, uni- and bilateral), retarded ossification of calvaria and a wide variety of sternal defects. Specific defects were bent radius and ulna, and bent tibia and fibula which increased with increasing dosages of dimethadione. Fetal mortality and incidence of skeletal anomalies were higher when the treatment was given on days 1--21 of gestation than on days 6--15 of pregnancy.

Abnormalities, Drug-Induced↗