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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 325 records · Page 18Linked to original sources
PubMed1997

Epilepsy in rural Haryana--prevalence and treatment seeking behaviour.

A community-based epidemiological study on epilepsy was conducted in rural North India in 1992-94 to estimate the extent of the problem and to study the treatment seeking behaviour of epilepsy patients. A key informant-based survey was conducted by a social worker to enlist suspect epilepsy cases in catchment population (30,000) spreading over in 40 villages of a primary health centre. These cases were verified by a neurologist. The prevalence of epilepsy was 4.2/1000 and it was more in males and in young children (> 6 to 15 years). Majority (81%) had already been diagnosed by qualified doctors. Many (57%) had a fit in last year. In 68% cases the disease onset was in childhood (up to 14 years). Half of the cases had the disease for 6 years or more. Multiple agencies were consulted by most (74%) of them. Faith healers and local practitioners (not medical graduates) were consulted as the first agency in 57% cases. Positive family history was elicited in 36% cases.

Adolescent↗
PubMed1997

Control of aromatase activity in breast tumours: the role of the immune system.

Cytokines such as interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF alpha), have been identified as important regulators of aromatase activity in fibroblasts derived from normal and malignant breast tissues, and may play an important role in controlling aromatase activity in breast tumours. The major source of such cytokines within breast tumours remains to be established but macrophages and lymphocytes, which can infiltrate tumours, have been identified as a potential source of aromatase stimulatory cytokines. To obtain further insight into the possible role played by the immune system in cancer development, and in particular its ability to regulate aromatase activity via cytokine production, we have obtained peripheral blood monocytes and lymphocytes from an immunosuppressed kidney transplant recipient, receiving cyclosporin A therapy, and a woman with breast cancer. Monocytes and lymphocytes were stimulated with lipopolysaccharide (LPS), and the conditioned medium (CM) collected from these cells was tested for its ability to stimulate aromatase activity in fibroblasts derived from normal breast tissue from a woman undergoing lumpectomy for the removal of a breast tumour. The white blood cell count was lower for the immunosuppressed patient, mainly because of the reduction in the number of monocytes and lymphocytes. The ability of CM from the monocytes and lymphocytes of the immunosuppressed patient to stimulate aromatase activity was significantly reduced (68% and 82% for monocytes and lymphocytes, respectively) compared with that of CM from the cells of the woman with breast cancer. It is possible, therefore, that immunosuppression, which has been found to be associated with a reduction in the incidence of de novo breast cancer in kidney transplant recipients, may exert its effect by inhibiting cytokine production by the cells of the immune system and thus oestrogen synthesis. In contrast to the stimulatory effects that TNF alpha has on aromatase activity in breast fibroblasts, in MCF-7 breast cancer cells, which possess low aromatase activity, it reduced activity. However, the extent of inhibition of aromatase activity in these epithelial cells was much lower than the marked stimulation which it can induce in breast fibroblasts.

Adult↗
PubMed1996

Chiral molecular self-assembly of phospholipid tubules: a circular dichroism study.

We report on spectroscopic studies of the chiral structure in phospholipid tubules formed in mixtures of alcohol and water. Synthetic phospholipids containing diacetylenic moieties in the acyl chains self-assemble into hollow, cylindrical tubules in appropriate conditions. Circular dichroism provides a direct measure of chirality of the molecular structure. We find that the CD spectra of tubules formed in mixtures of alcohol and water depends strongly on the alcohol used and the lipid concentration. The relative spectral intensity of different circular dichroism bands correlates with the number of bilayers observed using microscopy. The results provide experimental evidence that tubule formation is based on chiral packing of the lipid molecules and that interbilayer interactions are important to the tubule structure.

Alcohols↗
PubMed1996

In vivo activity of 4-methylcoumarin-7-O-sulfamate, a nonsteroidal, nonestrogenic steroid sulfatase inhibitor.

Steroid sulfatase regulates the formation of estrone from estrone sulfate (E1S) and dehydroepiandrosterone (DHA) from DHA sulfate. DHA can be converted to androstenediol, a steroid with potent estrogenic properties, and inhibition of steroid sulfatase activity is therefore an important therapeutic target. Because nonsteroidal steroid sulfatase inhibitors may offer some advantage for use in the treatment of breast cancer, 4-methylcoumarin-7-O-sulfamate (COUMATE) was synthesized and shown to be active in vitro. In this study, in vitro and in vivo techniques have been used to confirm that COUMATE, in contrast to the steroidal steroid sulfatase inhibitor estrone-3-O-sulfamate, is devoid of estrogenic activity. COUMATE did not stimulate the growth of MCF-7 breast cancer cells or uteri of ovariectomized rats, in contrast to estrone-3-O-sulfamate. COUMATE was orally active in vivo and after multiple dosing (10 mg/kg/day for 7 days) inhibited liver estrone sulfatase activity by 85%. Seven days after single or multiple dosing with COUMATE, liver estrone sulfatase activity was almost fully restored. Measurement of estrone sulfatase activity in WBCs revealed a degree of inhibition similar to that detected in liver samples. COUMATE was able to completely block the ability of E1S to stimulate uterine growth in ovariectomized rats. The development of a potent nonsteroidal, nonestrogenic steroid sulfatase inhibitor should allow the therapeutic potential of this type of therapy to be evaluated.

Animals↗
PubMed1996

Malignancy in chronic leg ulcers.

OBJECTIVE: To evaluate the frequency of malignant ulcers in patients presenting with leg ulcers. DESIGN: A descriptive study from data collected between July 1988 and June 1995 from 981 patients (2448 ulcers) attending a leg ulcer clinic. SETTING: A specialised leg ulcer clinic at a tertiary teaching hospital. SUBJECTS: 43 patients with 55 malignant skin lesions. OUTCOME MEASURES: Tissue biopsies in ulcerated lesions that suggested malignancy or were not responding to appropriate treatment. RESULTS: Forty-three patients were found to have malignant lesions on the legs, giving a frequency of malignant ulcers of 4.4 per 100 leg ulcer patients, or 2.2 per 100 leg ulcers. Seventy-five per cent of the malignant ulcers were basal cell carcinoma and 25% were squamous cell carcinoma. CONCLUSIONS: Malignant skin changes are common in chronic leg ulcers. A biopsy should be taken from all suspicious ulcers or ulcers that do not respond to appropriate treatment.

Aged↗
PubMed1996

External beam radiation for retinoblastoma: results, patterns of failure, and a proposal for treatment guidelines.

PURPOSE: To analyze treatment results and patterns of failure following external beam radiation for retinoblastoma and propose treatment guidelines according to specific clinical variables. METHODS AND MATERIALS: We analyzed 27 patients (34 eyes) with retinoblastoma who received external beam radiation as initial treatment at Hahnemann University Hospital from October 1980 to December 1991 and have been followed for at least 1 year. Of the 34 eyes, 14 were Groups I-II (Reese-Ellsworth classification), 7 were Group III, and 13 were Groups IV-V. Doses ranged from 34.5-49.5 Gy (mean 44.3 Gy, median 45 Gy) in 1.5-2.0 Gy fractions generally delivered through anterior and lateral wedged pair fields. RESULTS: At a mean follow up of 35.2 months (range 12-93 months), local tumor control was obtained in 44% (15 out of 34) of eyes with external beam radiation alone. Salvage therapy (plaque brachytherapy, cryotherapy, and/or photocoagulation) controlled an additional 10 eyes (29.5%), so that overall ocular survival has been 73.5%. Local tumor control with external beam radiotherapy alone was obtained in 78.5% (11 out of 14) of eyes in Groups I-II, but in only 20% (4 out of 20) of eyes in Groups III-V. A total of 67 existing tumors were identified prior to treatment in the 34 treated eyes and local control with external beam radiation alone was obtained in 87% (46 out of 53) of tumors measuring 15 mm or less and in 50% (7 out of 14) of tumors measuring more than 15 mm. When analyzing patterns of failure in the 19 eyes that relapsed, a total of 28 failure sites were identified and consisted of progression of vitreous seeds in seven instances (25% of failure sites) recurrences from previously existing tumors in 10 instances (36% of failure sites) and development of new tumors in previously uninvolved retina in 11 instances (39% of failure sites). CONCLUSIONS: 1) We find that external beam radiation to a dose of 45 Gy in fractions of 1.5 to 2.0 Gy provides adequate tumor control in retinoblastoma eyes Groups I-II (Reese-Ellsworth classification) or tumors measuring 15 mm in diameter or less. Eyes in more advanced group staging or containing tumors larger than the 15 mm seem to require higher radiation doses. We propose treatment guidelines for external beam radiation of retinoblastoma that specifically take into account the important clinical variables of tumor stage and patient age. 2) External beam radiation does not prevent the appearance of new tumors in clinically uninvolved retina. Therefore, the traditional belief that external beam radiation can treat the retina "prophylactically" should be seriously questioned. Due to this finding and their significant less morbidity, focal treatment modalities (plaque brachytherapy, photocoagulation, and/or cryotherapy), when clinically feasible, should be considered the treatment of choice for intraocular retinoblastoma. External beam radiation should be considered only when focal treatment modalities are not clinically indicated.

Dose-Response Relationship, Radiation↗
PubMed1996

Postnatal effect of arecoline on chlorophyllin-modulated hepatic biotransformation system enzymes in suckling neonate and lactating mice.

The present study evaluates the potential of arecoline alkaloid on chlorophyllin (CHL) modulated levels of hepatic biotransformation system enzymes in suckling neonate and lactating mice. CHL [50, 100, or 200 mg/kg body weight (b.w.)/day] induced significant increases in the hepatic levels of glutathione S-transferase (GST) and sulfhydryl (-SH) in lactating dams and suckling pups of 14 or 21 days. The depleted level of hepatic Cytochrome (Cyt.) P-450 was observed only in lactating dams given 200 mg/kg b.w. CHL. Arecoline (20 mg/kg b.w.) could depress the CHL-induced levels of hepatic GST and -SH, while Cyt. P-450 and Cyt. b5 levels remained unaltered by arecoline alone or arecoline plus CHL treatment. In lactating dams the modulated levels of hepatic biotransformation system enzymes potentially could affect the detoxication efficacy of administered chemicals besides influencing the rate and extent of passage of metabolites to suckling neonate.

Animals↗
PubMed1996

Fermentation of xylose and rice straw hydrolysate to ethanol by Candida shehatae NCL-3501.

Candida shehatae NCL-3501 utilized glucose and xylose efficiently in batch cultures. The specific rate of ethanol production was higher with mixtures of glucose and xylose (0.64-0.83 g g-1 cells d-1) compared to that with individual sugars (0.38-0.58 g g-1 cells d-1). Although the optimum temperature for growth was 30 degrees C, this strain grew and produced appreciable levels of ethanol at 45 degrees C. A stable ethanol yield (0.40-0.43 g g-1 substrate utilized) was obtained between 10 g L-1 and 80 g L-1 of initial xylose concentration. Conversion efficiency was further improved by immobilization of the cells in calcium alginate beads. Free or immobilized cells of C. shehatae NCL-3501 efficiently utilized sugars present in rice straw hemicellulose hydrolysate, prepared by two different methods, with 48 h. Ethanol yields of 0.45 g g-1 and 0.5 g g-1 from autohydrolysate, and 0.37 g g-1 from acid hydrolysate were produced by free and immobilized cells, respectively.

Candida↗
PubMed1996

Unilateral video-assisted thoracic surgical lung reduction.

BACKGROUND: Lung reduction has been demonstrated to be a promising treatment for end-stage emphysema when performed on both lungs via sternotomy. The role for a thoracoscopic approach has not yet been determined. METHODS: Unilateral video-assisted thoracic surgical lung reduction was performed on 50 patients for the treatment of end-stage emphysema. There were 34 men and 16 women with a mean age of 61.5 years (range, 31 to 78 years). Emphysema was secondary to smoking in 45 patients (90%), and alpha 1-antitrypsin deficiency in 5 patients (10%), 4 of whom had smoked in the past. Lung reduction was performed unilaterally using a thoracoscope and a stapled resection without the routine use of bovine pericardium. The side to be operated on and site of resection were determined preoperatively by examination of the perfusion and computed tomographic scans of the lungs. The average amount of lung removed was 59 +/- 15 g (range, 29 to 111 g). RESULTS: Morbidity included prolonged air leak in 15 patients (30%), bleeding in 3 (6%), pneumonia requiring reintubation in 3 (6%), myocardial infarction in 1 (2%), and perforated ulcer in 1 (2%). Seven patients (14%) required a second thoracic procedure for management of these complications. Two patients died, for an operative mortality of 4%. Follow-up obtained between 1 and 3 months in 25 patients revealed significant improvement in forced expiratory volume in 1 second (0.71 to 0.95 L; p < 0.001), forced vital capacity (2.24 to 2.58 L; p < 0.01), and oxygen tension (59 to 67 mm Hg; p < 0.01). The improvement in functional capacity as measured by 6-minute walk approached statistical significance (771 to 923 ft; p = 0.06). CONCLUSIONS: Significant subjective improvement in dyspnea has been noted in 41 of 48 hospital survivors (85%). For patients with end-stage emphysema, unilateral video-assisted thoracic surgical lung reduction appears to be a preferable alternative to standard medical management.

Adult↗
PubMed1996

Response of two cultivars of Triticum aestivum L. to simulated acid rain.

The present experiment was aimed at assessing the impact of simulated acidic precipitation (SAR) on growth, biomass accumulation and yield of two cultivars of wheat (Triticum aestivum L.), Malviya 206 and 234, varying in cuticular thickness and leaf area. Wheat cultivars were exposed to simulated rain acidified to pH 5.6 (control), 5.0, 4.5, 4.0 and 3.0 from 30 days of age, twice a week for five weeks. The plants received ambient precipitation of unknown acidity, as well as the acid rain treatments. Growth parameters such as shoot height, root length, and leaf area were reduced significantly in treated plants at different growth stages. Above and below-ground biomass also decreased significantly in the plants treated with acidic precipitation. Relative to control, the number of grains per plant and yield per m(2) declined significantly at all SAR treatments. The hypothesis that the variety with thinner cuticle and greater leaf area would be more susceptible to acidic precipitation was not supported by the present study.

Journal Article↗
PubMed1996

Molluscicidal activity of neem (Azadirachta indica A. Juss).

Molluscicidal property of Azadirachta indica A. Juss (neem) against the snails Lymnaea acuminata and Indoplanorbis exustus was studied. It was observed that the molluscicidal activity of the leaf, bark, cake, neem oil and the neem-based pesticides, achook and nimbecidine, was both time- and dose-dependent. The toxic effect of pure azadirachtin against both the snails was greater than the synthetic molluscicides.

Animals↗
PubMed1996

Hypoxic brain injury: evaluation by single photon emission computed tomography.

Single photon emission computed tomography (SPECT) with 99mTc-labeled hexamethylpropylene-amine oxime (HMPAO) was used to evaluate cerebral blood flow in 6 patients with hypoxic brain injury (HBI). The SPECT scans were compared with electroencephalograms (EEGs), magnetic resonance imaging (MRI) scans, or computer tomography (CT) scans. The findings on SPECT scans in all 6 patients supported the clinical impression of HBI. SPECT showed decreased perfusion in regions of the brain including the hippocampus, cerebellum white matter, rostral brain stem, the cortex, and occiput. MRI, CT, and EEG provided information that was often not representative of HBI. It was believed that SPECT provided more useful information in the identification of HBI. SPECT imaging with 99mTc HMPAO appears to be a valuable adjunct for evaluation and clinical diagnosis of HBI patients.

Adult↗
PubMed1996

Inducible nitric oxide synthase in vascular smooth muscle cells from prehypertensive spontaneously hypertensive rats.

The inducible nitric oxide synthase (iNOS) present in vascular smooth muscle cells (VSMC) may play a role in the generation of nitric oxide (NO) in the vascular wall, regulating blood vessel tone in normotension and hypertension. In this study the effect of interleukin (IL)-1 beta, a cytokine that induces iNOS, on NO generation (measured as nitrite), cyclic guanosine monophosphate (cGMP) generation, and steady-state abundance of iNOS mRNA were examined in VSMC from 3 week old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats, during the period preceding the elevation of blood pressure. With cell density dependent variations in nitrite production eliminated, VSMC from SHR and WKY did not differ in NO generation except after prolonged incubation (30 h), when SHR cells produced less NO. However, cGMP concentrations associated with IL-1 beta stimulation were significantly smaller in SHR VSMC than in cells from WKY. IL-1 beta stimulation resulted in increased abundance of iNOS mRNA to the same extent in both WKY and SHR VSMC. Inhibitors of NOS, NG-monomethyl-L-arginine (L-NMMA) and N omega-nitro-L-arginine methyl ester (L-NAME), did not block the induction of iNOS mRNA, although nitrite production and cGMP generation were inhibited. The protein synthesis inhibitor cycloheximide and the RNA synthesis inhibitor actinomycin-D almost completely blocked the production of nitrite in cells from both strains of rats. Actinomycin-D completely blocked the induction of iNOS mRNA by IL-1 beta in cells from both strains of rats, whereas cycloheximide partially blocked its synthesis in WKY, but had no significant effect on IL-1 beta induced expression of iNOS mRNA in SHR VSMC. Thus, IL-1 beta controls iNOS gene expression at the transcriptional level, and an intermediate labile protein, whose synthesis is inhibited by cycloheximide, is required for IL-1 beta stimulated induction of iNOS mRNA transcription in WKY cells but not in SHR. We conclude that although iNOS is expressed to similar extent in VSMC of prehypertensive SHR and WKY and similar amounts of NO are initially generated, there are differences between the VSMC of SHR and WKY in the regulation of the transcription of iNOS mRNA, there is a lower sustained production of NO, and there is a reduced generation of cGMP in response to IL-1 beta stimulated NO production. These differences between VSMC from prehypertensive SHR and WKY may indicate a pathophysiological role of iNOS in early blood pressure elevation in SHR.

Animals↗