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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 343 records · Page 19Linked to original sources

Chemoprevention of carcinogen-DNA binding: the relative role of different oxygenated substituents on 4-methylcoumarins in the inhibition of aflatoxin B1-DNA binding in vitro.

Eighteen 4-methylcoumarins bearing methoxy/hydroxy/acetoxy functionalities have been reported to effectively inhibit the rat liver microsome-mediated aflatoxin B1-DNA binding in vitro. The contribution of functionality on coumarin nucleus towards the inhibition of AFB1-DNA binding is in the order acetoxy > hydroxy > methoxy. The results illustrate the structure-activity relationship.

Aflatoxin B1↗

Vortex or whorl formation of cultured human corneal epithelial cells induced by magnetic fields.

The terms 'vortex keratopathy' and 'hurricane keratopathy' describe two similar conditions affecting the corneal surface. In the former, a vortex or whorl pattern is seen on the corneal surface and is due to the deposition of substances such as pigment, iron or drugs in the epithelial cells. In the latter, a similar pattern is presented by migrating epithelial cells but, unlike the former, the pattern is rendered more visible by fluorescein staining. Both represent the migratory pattern of normal epithelial cells which is otherwise not visible due to the slow rate of epithelial turnover and migration. The whorl pattern has a clockwise predisposition in the majority of cases and is hypothesised to be due to the influence of ocular electro-magnetic fields on the migrating epithelial cells. In this study we tested in vitro the effect of static magnetic fields on corneal epithelial cells. We were able to reproduce dramatic vortex or whorl patterns in response to magnetic fields, but without preferential migration towards the North or South Pole.

Adult↗

Effect of arecoline on the curcumin-modulated hepatic biotransformation system enzymes in lactating mice and translactationally exposed F1 pups.

The present study assesses the potential of arecoline alkaloid to translactationally modify the chemopreventive efficacy of curcumin (diferuloyl methane) via neonatal modulation of hepatic biotransformation system enzymes. Curcumin (0.4 g/kg body wt/day) induced a significant increase in the hepatic levels of glutathione-S-transferase (GST), acid-soluble sulfhydryl (SH), cytochrome b5, and cytochrome P-450 in lactating dams and F1 pups at 14 or 21 days. Arecoline (20 mg/kg body wt/day) could not modulate the hepatic GST and SH levels, although significant induction was observed in the levels of cytochrome b5 and cytochrome P-450 in dams and suckling pups. Significant enhancement of hepatic GST, SH, cytochrome b5, and cytochrome P-450 levels was observed in groups treated with curcumin+arecoline. Curcumin-induced levels of GST and SH were depressed whereas cytochrome b5 and cytochrome P-450 were further elevated by curcumin+arecoline treatment. The elevated levels of Phase I enzymes were more significant with exposure to curcumin+arecoline than with arecoline exposure alone. Modulation in competing potential pathways of biotransformation system enzymes in lactating dams may affect the rate and extent of maternal detoxication and thus influence the passage of metabolites of administered xenobiotics to the suckling neonate.

Animals↗

Modulatory influence of chlorophyllin on the mouse skin papillomagenesis and xenobiotic detoxication system.

The present study evaluates the modulatory potential of chlorophyllin (CHL) on the murine skin papillomagenesis pattern and its influence on the levels of biotransformation system enzymes. Topical application of CHL (100 mg/kg body weight/day) during peri-, post- or peri- and post-initiational stages of 7,12-dimethylbenz[a]anthracene (DMBA)-induced papillomagenesis, significantly (P < 0.01) reduced the (i) tumor burden to 3.68, 3.56 and 3.33 (positive control value: 5.89); (ii) cumulative number of papillomas to 59, 57 and 60 (positive control value: 112); and (iii) incidence of mice bearing papillomas to 88%, 88% and 90%, respectively (positive control value 100%). CHL treatment alone or during peri-, post-, or peri- and post-initiational stages significantly elevated the glutathione S-transferase (GST) and -SH levels in the liver and skin tissue of the murine system. The potential of CHL in modulating the process of carcinogenesis is suggested by the altered levels of biotransformation system enzymes. The implications of the biochemical changes and inhibition of tumor incidence by CHL are discussed.

9,10-Dimethyl-1,2-benzanthracene↗

Lymphocyte subset responses to exercise and glucocorticoid suppression in healthy men.

It is well established that in vivo changes in ratios of lymphocyte phenotype subsets is altered by glucocorticoid administration. To determine whether the lymphocyte response would be further affected by strenuous exercise, since glucocorticoids are released during exercise, 14 physically fit men were randomly given placebo (P), 4 mg of dexamethasone (DEX), or 100 mg of hydrocortisone (HCO) 4 h before high-intensity treadmill running. Blood was drawn pre- and immediately post-exercise; lymphocyte subsets (CD3, CD4, CD8, CD19, and CD56) were determined by flow cytometry. Pre-exercise CD3 and CD4 percentages were lower, whereas CD8 and CD56 were higher with DEX and HCO as compared to P. Exercise induced a lymphocytosis after all treatments, but subsets did not change proportionally. With P, DEX, and HCO, the magnitudes of change were comparable: CD3 and CD4 decreased and CD8 and CD56 increased. Notably, for all treatments exercise induced in approximately 2-fold increase in the percentage of cells expressing CD56 (natural killer cells). Thus, a single oral dose of DEX or HCO did not alter the direction or magnitude of immediate post-exercise changes in lymphocyte subset expression. Whether glucocorticoid pretreatment influences lymphocyte responses during recovery from strenuous exercise remains to be determined.

Anti-Inflammatory Agents, Non-Steroidal↗

Hyperthyroidism manifested as hypercalcemia.

A patient with hypercalcemia was found to have thyrotoxicosis and no other underlying cause for the elevated serum calcium level. Radioiodine therapy relieved hyperthyroidism and hypercalcemia. We discuss the incidence of hypercalcemia in patients with thyrotoxicosis and mechanisms for hypercalcemia in hyperthyroidism.

Adult↗

Hyperlipidemia in children: the role of uremia, steroids and cyclosporine therapy.

At present, there are very few studies that look at the effect of uremia, prednisone and cyclosporine therapy on the lipid profiles of children. This effect is important because of the potential association of hyperlipidemia and increased risk of cardiovascular morbidity and mortality and glomerulosclerosis. We measured fasting lipid profiles in 73 children. There were 21 controls, 18 patients treated with cyclosporine and prednisone, 9 patients treated with cyclosporine alone and 25 dialysis patients. Lipoprotein (a) levels were measured using direct binding 'sandwich' ELISA. Uremic children had higher levels of triglycerides and very-low-density lipoprotein as compared with the control group. Children receiving combination of cyclosporine and prednisone also had higher total cholesterol, triglycerides, low-density lipoprotein, very-low-density lipoprotein as compared to the control group. However, children receiving cyclosporine monotherapy had lipid profiles similar to the control group. Patients receiving cyclosporine and prednisone had higher total cholesterol, high-density lipoprotein and low-density lipoprotein as compared with the dialysis group. Evaluating lipoprotein (a) levels, children on cyclosporine monotherapy had lower lipoprotein (a) levels as compared with children on dialysis and those receiving both combination therapy. The total cholesterol/high-density lipoprotein-cholesterol ratio (TC/HDL) was similar among the study groups. In summary, uremic children and children receiving steroids with cyclosporine have elevated lipid levels. However, the increased risk for atherosclerosis is not evident because of similar levels of lipoprotein (a) and TC/HDL ratios among the study groups.

Adolescent↗

Lupus nephritis in children: a longitudinal study of prognostic factors and therapy.

There are only a few studies in the pediatric literature that have analyzed risk factors for renal failure in childhood lupus nephritis. This study reviewed the outcome of 56 children (4 to 18 yr of age) with lupus nephritis seen at the authors' institution over a 27-yr period (1965 to 1992), in relation to risk factors and therapy. All children underwent percutaneous renal biopsy before the institution of therapy. From 1965 to 1987, treatment for Class III and IV lupus nephritis consisted of high-dose pulse methylprednisolone, 500 mg daily for 10 days, followed by oral prednisone. From 1987 to 1992, IV cyclophosphamide was given monthly for 6 months and then every 3 months for a period of 3 yr for patients with Class III and Class IV disease. Of 56 children, 42% had Class IV and 21% had Class III histology at onset. The mean follow-up period was 4 yr and ranged from 0.5 to 20.3 yr. Life-table analysis showed that the cumulative proportion of patients surviving was 82.8% at 5 yr and 67.7% at 10 yr. Renal survival was 44.4% at 5 yr and 29% at 10 yr, after the initial diagnosis of lupus nephritis was made. Age at diagnosis, race, sex, initial serum creatinine level, and the presence of proteinuria, hypertension, and DNA antibody titers were reviewed with respect to disease progression, as was the histological class at diagnosis. The effect of the different therapies was also examined. Univariate analysis revealed a significant association of progression to ESRD with an elevated serum creatinine level (P = 0.021), decreased C3 complement (P = 0.024), hypertension (P = 0.053), and histological classification of Class IV lupus nephritis (P = 0.031). Multivariate analysis demonstrated that progression to ESRD was independently associated with an initial Class IV histology (relative risk, 1.78; P < 0.003), hypertension at presentation (relative risk, 1.67; P < 0.003), and a low C3 complement level in conjuction with a high creatinine level (relative risk, 1.52; P < 0.028). Among children with lupus nephritis, those with Class IV disease, hypertension, high creatinine levels, and low C3 complement levels at the time of diagnosis are at increased risk for ESRD. Initial histological classification of lupus nephritis was the most reliable prognostic factor for disease progression. This study was unable to detect a difference in outcome for the two treatment groups.

Adolescent↗

Epidemiology of inclusion body hepatitis in poultry in northern India from 1990 to 1994.

The epidemiology of inclusion body hepatitis (IBH) was studied in poultry in northern India, from April 1990 to March 1994, to evaluate the various factors responsible for causing and determining the severity of the disease. Broiler chicks and Japanese quail (Coturnix coturnix japonica) were the species examined. The factor observed to be most commonly associated with IBH was the presence of aflatoxins in the feed at higher than permissible levels, i.e. 20 parts per billion. Avian adenovirus-1 was isolated from the livers of affected birds. In the final year of the study, a number of outbreaks of IBH caused heavy mortalities among three to five-week-old broiler chicks, which displayed typical IBH lesions in addition to hydropericardium.

Adenoviridae Infections↗

Alterations in the systemic acid-base status and blood gas dynamics during progressive hypocalcaemia in cow calves.

Hypocalcaemia, induced in cow calves by slow infusion of Na2EDTA for 6 hr, led to biphasic changes in acid-base status. Decrease in ionized plasma Ca2+ concentration upto 0.82 +/- 0.06 mmole 1(-1) was associated with metabolic alkalosis. Further decrease in ionized plasma Ca2+ concentration (0.61 +/- 0.09 mmole 1(-1)) led to metabolic acidosis, superimposed by a respiratory component. There was significant decrease in oxygen tension and saturation of arterial blood as well as impaired uptake of oxygen by peripheral tissues and pulmonary blood.

Acid-Base Imbalance↗

Ultrastructure of liver from piglets fed Tower rapeseed oil.

Effect of Tower rapeseed oil (RO) containing lower (0.4%) erucic acid on the piglet liver was studied by electron microscopy. The animals were placed in two groups of four and were fed the diets for eight weeks. Animals in the treated group were given a basal diet comprising corn-soybean plus Tower RO at a 10% concentration; animals that were given the basal diet with no added oil served as the controls. Architecture of the liver from animals of the control group appeared normal. Ultrastructural changes in the liver of RO-fed animals included dilation of lumens and loss of microvilli in bile canaliculi. In addition, closely aligned mitochondrial cristae, elevated number of peroxisomes, and an unusual increase in the size and number of membrane bound spaces in zone 3 of liver acini were noticed. These alterations may reflect a disturbance in piglet liver functions following Tower RO feeding.

Animals↗

Toxicity of PCB 156 in the rat liver: an ultrastructural and biochemical study.

PCB 156 (2,3,3',4,4',5-hexachlorobiphenyl) congener was given to weanling Sprague-Dawley rats in diets prepared by mixing it in 4% corn oil. The animals were placed in eight groups, each comprising 10 males or females and received diets that contained 0.01, 0.1, 1, 10 ppm PCB; in addition, two control groups of rats of each gender were given diets mixed with corn oil. Thirteen weeks after commencement of dosing, animals were euthanized and liver specimens were harvested and prepared for transmission electron microscopy. Hepatocyte architectural alterations comprised augmentation of smooth reticulum profiles and mitochondria with unorthodox cristae in animals regardless of gender from 1 and 10 ppm groups. Hepatic microsomal aminopyrine-N-demethylase was elevated significantly in both genders at highest (10 ppm) congener concentration. Based on our previous work, PCB 156 is estimated to be more toxic than PCB 153 or 28 in terms of liver morphologic expressions.

Administration, Oral↗

Community based estimation of perinatal mortality through record linkage.

OBJECTIVE: To estimate perinatal mortality through record linkage of Health Workers (HW) and Anganwadi Workers (AWW) in rural Haryana. DESIGN: Retrospective analysis of records (1991-92) of HW and AWW. Enquiry and home visits were made for tracing the fate of pregnancy in cases with incomplete records. SETTING: In 1993-95 in 45 villages selected purposively in Raipur Rani block, Ambala. MAIN OUTCOME MEASURE: Enlisting of perinatal deaths as the main outcome measure through scrutiny of records of HW and AWW. RESULTS: Perinatal mortality rate (PMR) was 42.25 and 45.78 per thousand births as per the record of HW and AWW, respectively for the 23 villages for whom records of both were available. Support by enquiry or home visit yielded a PMR of 59.42 for combined HW and AWW sources and 51.66 per 1000 births for AWW source alone. Concordance between AWW and HW records for fate of pregnancy was moderate (K = 0.46; 95% CI 0.35-0.57). CONCLUSIONS: There is a lack of a system of record linkage between and within the records of HW and AWW at primary health care level. AWW data was more accurate and up-to-date as compared to HW. Reasonably accurate estimates of perinatal mortality rate can be made through record linkage.

Child↗

Prevalence of tuberculosis in Kishtwar Tehsil of Jammu region in Jammu and Kashmir State.

A study of prevalence of tuberculosis in Kishtwar tehsil of Jammu region was conducted from June 1991 to May 1992. A total of one thousand two hundred ninety-eight rural as well as urban population suffering from various types of lung diseases was studied for prevalence of tuberculosis and a sizeable number (98) of patients were found to be positive of various types of tuberculosis, viz, pulmonary tuberculosis, tuberculous pleural effusion and miliary tuberculosis. Of the population studied 7.55% were found to be positive for tuberculosis and among them 88.76% patients were anaemic and the commonest type of anaemia was normocytic normochromic and normocytic hypochromic. The ESR was raised in almost of all the patients. Of the population, 80.61% were seen to be positive on skiagram chest and 58.16% were found to be positive on other diagnostic tests like Mantoux's tests, sputum for acid-fast bacilli, etc. Mantoux's test was positive in 27.55% cases and sputum was positive in 30.61% cases. All the cases studied were subjected to special investigations. The changes in parameters are consistent with the diagnosis of tuberculosis. Large family size, poverty, excessive smoking, illiteracy, etc, are the major contributing factors.

Adolescent↗

Evaluation of risk factors for fatal neonatal sepsis.

OBJECTIVE: To evaluate risk factors for fatal neonatal sepsis. DESIGN: Prospective study. SETTING: Referral neonatal unit of a teaching hospital. SUBJECTS: 171 neonates admitted with sepsis. METHODS: Clinical examination and investigations on the day of admission were recorded and the neonates followed up to determine the final outcome. RESULTS: The overall fatality was 48.5%. In the univariate analysis, the factors significantly associated with death were weight, gestational age, age at onset of sepsis, hypothermia, requirement of IPPV, presence of refractory septic shock, neutropenia, metabolic acidosis and raised prothrombin time. However, in the multivariate analysis, only neutropenia, metabolic acidosis, increased prothrombin time and refractory septic shock retained their significance. The adjusted odd's ratio (95% confidence interval) were 0.095 (0.04 = 0.22), 1.14 (1.04-1.25), 1.04 (1.002-1.08) and 11.82 (5.47-69.40), respectively. CONCLUSION: Even in a setting with high fatality rates, high risk of mortality in neonatal sepsis can be identified and targeted for intensive intervention.

Analysis of Variance↗