Browsing by Author "R. Padmanabhan"

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A quantitative assessment of post-natal development in CF rats
(1978) R. Padmanabhan; S. Singh
The post-natal development in CF rats from 5 litters was followed anthropometrically from the day of delivery to day 75. Weight, CR length, tail length and patello-calcaneal length of individual rats were measured every day and the rate of gain per day was calculated for each parameter. During this period, the rate of gain in weight showed two peaks (from days 26 to 30 and 56 to 60). The CR length and tail length had only one such peak (from days 16 to 20 and 21 to 25, respectively). The patello-calcaneal length rather exhibited an initial fall in the rate of growth up to day 45 followed by a slight increase till day 50 after which it became steady. Robustness was found to be maximum in the first few days after birth. Body weight showed better correlations with other parameters than the gross age. The growth curves appeared as straight lines having breaks, indicating that though the growth was exponential it had sudden changes in its rate.
Axial skeletal malformations associated with cranioschisis aperta and exencephaly: the result of experimental intervention after the neural tube closure in rats
(Informa Healthcare, 1983) R. Padmanabhan; Shamer Singh
Maternal administration of a single dose of cyclophosphamide (20 mg/kg) after the neural tube closure (on day 12) resulted in exencephaly and cranioschisis in 100% of rat fetuses at term. Extensive hemorrhages and edema were regularly associated with these defects. Alizarin-red stained skeletal preparations revealed absence of skull vault, premature closure of basicranial synchondroses, exaggeration of the craniovertebral angle, and agenesis and hypoplasia of the vertebrae, ribs and sternum. It is suggested that failure of the neural tube to close is not the primary cause of axial skeletal malformations and even after closure, the axial skeletal anlagen remains susceptible to teratogenic insult. © 1983 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
Chlorpromazine effect on fetal brain in rats
(1978) R. Padmanabhan; S. Singh
[No abstract available]
Chlorpromazine effect on the fetal brain in rats
(1978) R. Padmanabhan; S. Singh
[No abstract available]
Comparison of teratogenicity of acetaldehyde and ethanol in the rat
(1982) R.N. Sreenathan; R. Padmanabhan; S. Shigh
[No abstract available]
Congenital anomalies of the eye: An experimental model
(1982) S. Singh; R. Padmanabhan; K.S. Mehra
[No abstract available]
Congenital malformations of the auditory apparatus induced by hypervitaminosis A in rat foetuses
(1980) G. Singh; R. Padmanabhan; S. Singh
Malformations of the external ear invariably associated with those of middle and internal ear were reported in 20 day rat fetuses, following maternal administration of 100,000-200,000 lacs I.U. of vitamin A to pregnant rats between 8th-14th days of gestation. In the present study, fetuses with apparently normal external ears were examined histologically and found to have equally severe malformations of the middle ear cavity, ear ossicles, cochlear and the semicircular canals which highlights the inadequacy of mere surface examination as a method of estimation of a teratogenic effect.
Dose-dependent toxicity and reduction deformity of hind limbs in CF rat fetuses: An experimental study
(1984) N. Jeyaseelan; S. Singh; R. Padmanabhan
[No abstract available]
Ear anomalies in rat fetuses induced by maternal administration of cyclophosphamide: A preliminary report
(1981) S. Singh; R. Padmanabhan
[No abstract available]
Effect of acetaldehyde on skeletogenesis in rats
(1984) R.N. Sreenathan; Shamer Singh; R. Padmanabhan
Acetaldehyde (ACH), the metabolite of ethanol was administered to pregnant CF rats intraperitoneally (50 mg/kg) from day 8 through 15 of gestation and fetuses from different mothers were collected from day 16 through 21 of gestation. Fetuses were processed for alizarin skeletal staining. There was significant delay in ossification besides certain skeletal malformations such as wavy ribs. The delay in ossification may be one of the reasons for reduced birth weight and increased postnatal mortality and growth. © 1983.
Effect of chlorpromazine (CPZ) on developing rat brain. A morphological and histological study
(1978) S. Singh; R. Padmanabhan
A single intraperitoneal injection of CPZ(50mg/kg) was administered to pregnant rats on day 12 of gestation and fetuses were collected on day 20 of gestation. The brains of treated fetuses measured after fixation showed statistically significant reduction in weight (P < 0.001) and in various dimensions of their different parts (P < 0.001). The treated fetuses were also markedly stunted as judged by their weights. However, the weights of brains in the experimental group showed negative correlation with body weight indicating positive reduction in brain size. Histological examination revealed hydrocephaly in 83% of the treated cases. Hydrocephalic brains also showed reduction in cellularity of their cortices. Degenerative neuronal vacuolisation was observed in brains of all treated cases even if there was no ventricular dilatation.
Effect of chlorpromazine on skeletogenesis: the result of maternal administration of the drug in experimental rats
(Informa Healthcare, 1979) Shamer Singh; R. Padmanabhan
Chlorpromazine hydrochloride (CPZ) is known to induce intrauterine and extrauterine growth retardation. A single dose of CPZ (100 mg/kg) was administered to pregnant CF rats on the 14th day of gestation (sperm positive = day 0). Fetuses were collected from the 16th to the 20th day of gestation and processed for alizarin red-S stain. Ossification was delayed by 1 to 3 days in the long bones of the extremities, by 1 day in the scapulae and by 2 to 3 days in the ilium. Ischium and pubis remained unossified until the 20th day of gestation. Ossification of the skull bones was also delayed as manifested by the presence of wide sutures in the treated cases. the number and range of ossified vertebral bodies and arches in the treated group were always less than those in the control group. the sternebrae were most affected. the ribs also showed a significant delay in maturity. © 1979 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
Effect of intrauterine position on foetal weight in CF rats
(1981) R. Padmanabhan; S. Singh
The effect of intrauterine position on foetal weight was assessed in 20 litters of normal CF rats. Only the ovarian, ovarian penultimate, intermediate, cervical penultimate and cervical positions were considered. The mean foetal weight, standard deviation, standard score and mean percentile ranking were calculated for each position. The intermediate position was found to be associated with more number of heavier foetuses as evidenced from the percentile ranking. The incidence of stunting was maximum at the cervical end.
Effect of low doses of ethanol on fetus and fetal milieu in rat
(1983) R.N. Sreenathan; R. Padmanabhan; S. Singh
Very low doses of ethanol (75, 200 or 300 mg/kg) were administered (ip) to pregnant CF rats daily throughout the period of organogenesis (day 8 to 15 of gestation)(sperm positive day = day 1). Fetuses collected at term showed gross malformation like microcephaly, micrognathia, micromelia, hemorrhage and digital anomalies which are in keeping with the malformations associated with fetal alcohol syndrome assessed clinically. Intrauterine growth retardation was evident from the significant reduction in body weight, crown rump length, tail length and transumbilical distance and impaired skeletogenesis as revealed by alizarin red preparations. The placental weight and umbilical cord length were reduced, and the amniotic fluid weight increased. It is suggested that even at these low doses, alcohol is terotogenic, probably due to ready conversion of alcohol into acetaldehyde, following intraperitoneal administration.
Effect of maternal hypervitaminosis A during late gestation on pre- and postnatal lung maturation in rat
(1983) S. Singh; R. Padmanabhan; G. Singh; G. Kaur
The effect of hypervitaminosis A on lung maturation was studied in rats following treatment (1.5-2 lac IU-Arovit) during late gestation (days 16-19,sperm+=day 0). One group of both treated and control animals was collected on day 20 of gestation and the other allowed to proceed for delivery. The treated fetuses of the first group showed significantly higher (P<0.001) mean volume/weight of amniotic fluid. The foam test positive cases (6%) in treated group were also significantly less as compared to control fetuses (85%). Histological examination of lungs of treated fetuses of this group showed differentiation being delayed by 2 days. In the second group, the donryu offsprings showed higher perinatal mortality, smaller litter size, low birth weight, delayed suckling and respiratory distress. Histological examination of the lungs of treated pups from postnatal day 1-7 revealed poor differentiation of pulmonary tissue, thick septae, near absence of secondary septae, delayed vascularisation as compared to control specimens which showed extensive elaboration of alveoli and secondary septae.
Effect of maternal hypervitaminosis A during late gestation on the offspring in the rat
(1980) R. Padmanabhan; S. Singh; G. Singh
[No abstract available]
Effect of maternal starvation during pregnancy on the postnatal growth in rats
(1980) R. Padmanabhan; S. Singh
Body weight, crown-rump (CR), tail and patellocalcaneal (PCL) lengths of the offspring of female rats starved for 24 hr on day 14 of gestation were compared with those of controls till postconception day 90. Growth retardation was evident with respect to all the parameters. There was no recovery in the patellocalcaneal length.
Effect of natural litter size on the post-natal growth in CF rats
(1980) R. Padmanabhan; Shamer Singh
The litter effect among natural litters (with minimal differences in size i.e. 6, 8 and 9) on the growth was studied in CF rats from post-conception (PC) day 22 to 90 by somatometric techniques. Body weight was found to be significantly low in larger litters up to PC day 50 although the difference persisted numerically until PC day 90. Crown-rump length, tail length and patellocalcaneal length were significantly (< 0.001) reduced in larger litters. Growth rate curves substantiated these observations. Since the differences in size among the three groups of litters were too small to cause any nutritional deprivation and the natural potential for growth was not altered, differences in mother-offspring and/or off- spring-offspring emotional interactions could be the possible factor responsible for the growth rate differences. © 1980 S. Karger AG, Basel.
Growth retardation in rat fetuses induced by chlorpromazine hydrochloride (CPZ)
(1979) S. Singh; R. Padmanabhan
Maternal administration of 100 mg/kg of chlorpromazine hydrochloride on 14th gestation day led to a significant (P < 0.001) intrauterine growth retardation (IUGR) in rat fetuses collected from 16th - 20th days of gestation. Besides weight of the fetus, other measurements were used to assess the stunted growth, e.g. CR length, tail length and trans-umbilical distance (TUD). The latter was as efficacious as the weight since with each one of them the IUGR was found in 88% of fetuses at - 2SD level on 20th day of gestation. The different components of the fetal environments, e.g. weight and volume of placenta, length of the umbilical cord, weight and volume of amniotic fluid were also investigated which showed a positive correlation between alteration in the fetal environment and IUGR.
Histopathological changes of placenta induced by cyclophosphamide in mice
(1980) R. Padmanabhan; S. Singh
Following injection of a single dose of 12 mg/kg cyclophosphamide to pregnant mice on day 9 of gestation, the fetuses and placentae were collected on day 18. Fetuses showed various abnormalities and growth retardation. The placentae were lighter. The decidua exhibited hemorrhage, necrosis and infarction. The basal zone contained clumps of glycogen cells and more giant cells than the controls. The labyrinths were hyalinised. The trichorial placental barrier was thicker due to failure of the fetal mesenchyme to disappear. The arborization of fetal vasculature was reduced. The necrotic patch at the rim was found to contain acidophilic matrix and giant cells. Such pathological changes and their consequent interference with the fetal supply line are suggestive of their probable role in fetal growth retardation and malformations induced by cyclophosphamide.