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Biomedical subjects

S Chandna

Publications and source records attributed to S Chandna.

11 recordsLinked to original sources
PubMed2004

Radiation responses of Sf9, a highly radioresistant lepidopteran insect cell line.

PURPOSE: Lepidopteran insect cells are known to exhibit very high radioresistance. Although very effective DNA excision-repair has been proposed as a contributing factor, a detailed understanding of insect cell radiation responses has not yet been obtained. Therefore, the study was carried out to understand the in vitro radiation responses of Sf9 lepidopteran cells. MATERIALS AND METHODS: Exponentially growing asynchronous Sf9 cells (derived from ovaries of Spodoptera frugiperda) were exposed to gamma-radiation doses of 2-200 Gy. Cell survival, growth inhibition, cell cycle progression delay, alterations in cell morphology as well as induction of DNA damage, micronuclei and apoptosis were studied at various post-irradiation time intervals. RESULTS: Biphasic survival response curves were obtained with D0 rising from 20 Gy (at doses < or = 60 Gy) to 85 Gy (between 60 and 200 Gy), corroborating earlier reports on lepidopteran cells. An additional downward deviation at 2 Gy indicated a hypersensitive response. Dose-dependent growth inhibition with a transient G2 delay starting 12 h and extending up to 48-96 h was observed at doses of 10-200 Gy, while a brief G1/S transition delay was observed only at higher doses (> or = 100 Gy). Significant DNA damage was detected only at 20 Gy and higher doses, in contrast with human cells that showed similar damage at 2 Gy. Interestingly, micronuclei were not induced at any of the doses tested, although spontaneous micronucleation was evident in <1% of cells. Lack of micronucleus induction even at doses that induced significant DNA damage and a transient G2 block (20-50 Gy) strongly indicated a role of holocentric lepidopteran chromosomes. Apoptosis was detected only in a small proportion of cells (3%) exposed to 200 Gy, and cell/nucleus size and granularity increased by 72-96 h post-irradiation in a dose-dependent manner. Sf9 nucleoids extracted at 2 M NaCl showed higher compactness than the nucleoids prepared from human cells. CONCLUSIONS: It is clearly shown that lepidopteran cells are highly resistant to the induction of DNA damage and micronuclei, and display very low induction of apoptosis at doses up to 200 Gy. While the lack of micronucleus induction seems to be primarily due to the holocentric nature of their chromosomes, certain unique signalling pathways might be responsible for the low induction of apoptosis. Factors causing protection of Sf9 cellular DNA from radiation-induced damage are presently being investigated.

Animals↗
PubMed2001

Relation between plasma leptin and anthropometric and metabolic covariates in lean and obese diabetic and hyperlipidaemic Asian Northern Indian subjects.

This study investigated the relationship of plasma leptin to obesity, diabetes and hyperlipidaemia in Asian Northern Indian subjects, considered to have a predisposition to abdominal obesity and metabolic syndrome. A total of 72 subjects, subcategorised into lean and obese healthy subjects, lean and obese Type 2 diabetic and lean and obese non-diabetic hyperlipidaemic subjects were recruited. High leptin values were observed in all obese groups, and obese diabetic patients showed the highest levels. In lean and obese diabetic subjects, plasma leptin did not show any correlation to any index of glycaemia. When all lean and all obese subjects were analysed in two separate groups, body mass index (BMI), percent total body fat, and body density significantly correlated with the plasma leptin levels (p<0.05). Leptin values, when correlated to all variables in all patients taken together, showed the greatest magnitude of correlation with BMI (r=0.64), percent total body fat (r=0.67), and waist circumference (r=0.51). Strong inverse correlation was seen with body density (r=-0.67). Levels of serum insulin did not show any correlation with leptin levels in all subjects combined, and separately in various groups. Multiple linear regression analysis performed in obese, non-diabetic and normolipidaemic subjects, all Type 2 diabetic and all non-diabetic hyperlipidaemic subjects separately showed that percent total body fat is the only significant predictor of plasma leptin concentration in all the 3 groups. The present study suggests that plasma leptin has a strong positive correlation with percent total body fat in Asian Northern Indian subjects. Among other components of metabolic syndrome, only abdominal obesity is weakly correlated to serum leptin levels.

Adipose Tissue↗
PubMed1998

Radioprotective effects of DNA ligands Hoechst-33342 and 33258 in whole body irradiated mice.

Radioprotective effects of bisbenzimidole derived DNA ligands Hoechst-33342 (H-342) and Hoechst-33258 (H-258) have been investigated in whole body irradiated stain-A and Balb/c mice (Co-60 Gamma-ray, absorbed doses of 2.5 to 10 Gy delivered at dose rates of 0.01 to 0.50 Gy/min). Biodistribution of Hoechst dyes (2 or 5 mg/kg, body wt., i.v.) and their effects on cell cycle kinetics in bone marrow were studied by flow cytometry. Protection against radiation-induced chromosomal aberrations, micronuclei formation, alterations in DNA content dispersion, inhibition of erythropoiesis and animal lethality were investigated. Significant amount of DNA bound Hoechst could be observed in liver, intestine, kidney and brain for more than 14 days after its administration, while in the bone marrow cells, a reduction in the bound Hoechst was noticed after 7 days. H-342 significantly reduced the radiation-induced chromosome aberrations mainly due to a decrease in the frequency of acentrics (nearly 30%), while a marginal decrease (10%) in the dicentrics was observed at all the dose rates studied. Both H-342 and H-258 reduced the radiation-induced micronuclei formation in a dose dependent manner (2-10 mg/kg body wt.) and this protective effect was observed up to 6 days after the administration. Neither of the two compounds induced any cytogenetic damage in the bone marrow cells of unirradiated animals nor induced tumours at the doses used here (< 5 mg/kg, body wt. i.v.). Reduction in cytogenetic damage of bone marrow cells led to a faster recovery of erythropoesis as observed by increased PCE/NCE ratio in the peripheral blood erythrocytes of the animals which received Hoechst before irradiation. H-258 (5 mg/kg body wt.) given 18 hr before irradiation reduced radiation-induced animal death (5-9 Gy), while no significant effect was observed at higher doses (10 Gy). However, H-342, which has a higher cell permeability, even at a lower dose (2 mg/kg body wt.) showed significant protection at 10 Gy. The protective effects could be enhanced further, by combining these DNA binding agents with the glucose analogue, 2-deoxy-D-glucose (2-DG) which has been shown earlier to protect bone marrow cells against radiation damage.

Animals↗
PubMed1996

The Whitaker hook in the treatment of posterior urethral valves.

OBJECTIVE: To assess the efficacy of the Whitaker diathermy hook in the treatment of posterior urethral valves (PUV). PATIENTS AND METHODS: Seventeen patients with PUV underwent primary treatment under general anaesthesia using a diathermy hook. The results were assessed by the clinical course of the patient, serial measurements of serum creatinine level and repeat cystography 6 weeks and 6 months after treatment. RESULTS: There were no complications in 12 patients and they required no further treatment of the valves. Three patients required a repeat procedure which resolved the urethral obstruction. Two patients continued to show incomplete disruption of the valves and required endoscopic treatment. Two patients developed ureteric obstruction after disruption of the valves, which was treated by supravesical diversion and later reversed with no further treatment of the valves. CONCLUSIONS: The Whitaker diathermy hook is a safe and effective instrument which has not gained its rightful place in the treatment of patients with PUV.

Creatinine↗
PubMed1991

Presence of embryotoxic factor in the sera of neonates affected by myelomeningocele: a study on chick embryo.

An experimental study on chick embryos was conducted where 0.02 mL of serum, taken from five neonates (1 to 7 days of age) with myelomeningocele was injected separately into the fertile white leghorn eggs, at zero hour of incubation. A total of 150 experimental and 135 control eggs were injected. It was observed that the embryos of chick exposed to experimental serum had an increased frequency of embryonic death and/or gross abnormalities as compared with the control group (chi 2 = 32.07; P less than .001). The anomalies observed were those of neural tube, gastrointestinal system, and musculoskeletal system. In addition, there was a generalized growth retardation among experimental embryos. These malformations are probably due to an embryotoxic factor, which is present in the serum of the baby with myelomeningocele and has been transmitted transplacentally.

Animals↗
PubMed1989

Accessory limb associated with spinal bifida.

A neonate with three legs associated with spina bifida cystica and accessory rudimentary external genitalia is presented. A detailed radiologic workup was done preoperatively. The nomenclature and morphogenesis of this anomaly is briefly discussed.

Female↗
PubMed1987

Hemangiolymphangioma of the urinary bladder in a child.

A rare case of hemangiolymphangioma of the urinary bladder with associated cutaneous hemangiomas of the shaft and glans penis and the scrotum is presented. Unusual features of clinical presentation, noninvasive diagnosis, and the surgical management are discussed.

Child↗