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Biomedical subjects

U Singh

Publications and source records attributed to U Singh.

At least 37 records · Page 2Linked to original sources
PubMed2001

Pretransitional optical activity of short-pitched chiral nematic liquid crystals.

We have developed, using the de Gennes theory of short-range orientational order in the isotropic phase, a closed-form expression for the temperature dependence of the pretransitional optical activity of chiral nematics. Detailed calculations are included and the results are expressed in a form that can be easily tested experimentally. The theoretical predictions are supported by experimental data.

Journal Article↗
PubMed2001

Comparative biochemical and immunocytochemical studies reveal differences in the effects of Clostridium perfringens enterotoxin on polarized CaCo-2 cells versus Vero cells.

Since most in vitro studies exploring the action of Clostridium perfringens enterotoxin (CPE) utilize either Vero or CaCo-2 cells, the current study directly compared the CPE responsiveness of those two cell lines. When CPE-treated in suspension, both CaCo-2 and Vero cells formed SDS-resistant, CPE-containing complexes of approximately 135, approximately 155, and approximately 200 kDa. However, confluent Transwell cultures of either cell line CPE-treated for 20 min formed only the approximately 155-kDa complex. Since those Transwell cultures also exhibited significant (86)Rb release, approximately 155-kDa complex formation is sufficient for CPE-induced cytotoxicity. Several differences in CPE responsiveness between the two cell lines were also detected. (i) CaCo-2 cells were more sensitive when CPE-treated on their basal surface, whereas Vero cells were more sensitive when CPE-treated on their apical surface; those sensitivity differences correlated with CPE binding the apical versus basolateral surfaces of these two cell lines. (ii) CPE-treated Vero cells released (86)Rb into both Transwell chambers, whereas CaCo-2 cells released (86)Rb only into the CPE-containing Transwell chamber. (iii) Vero cells express the tight junction (TJ) protein occludin but (unlike CaCo-2 cells) cannot form TJs. The ability of TJs to affect CPE responsiveness is supported by the similar effects of CPE on Transwell cultures of CaCo-2 cells and Madin-Darby canine kidney cells, another polarized cell forming TJs. Confluent CaCo-2 Transwell cultures CPE-treated for >1 h formed the approximately 200-kDa CPE complex (which also contains occludin), exhibited morphologic damage, and had occludin removed from their TJs. Collectively, these results identify CPE as a bifunctional toxin that, in confluent polarized cells, first exerts a cytotoxic effect mediated by the approximately 155-kDa complex. Resultant damage then provides CPE access to TJs, leading to approximately 200-kDa complex formation, internalization of some TJ proteins, and TJ damage that may increase paracellular permeability and thereby contribute to the diarrhea of CPE-induced gastrointestinal disease.

Actins↗
PubMed2001

Se-methylselenocysteine activates caspase-3 in mouse mammary epithelial tumor cells in vitro.

Se-methylselenocysteine (MSC) inhibits mouse mammary epithelial tumor cell (TM6) growth. When synchronized TM6 cells were exposed to 50 microM MSC, either for 30 minutes or continuous, the 116 kDa poly(ADP-ribose)polymerase (PARP) was cleaved to an 85 kDa fragment indicative of cells undergoing apoptosis. The earliest cleaved PARP appears at 24 hr time point followed by elevated levels of 85 kDa fragment at 34 hr and 48 hr time points when the cells were exposed to continuous treatment with MSC. Results also showed that MSC increased caspase-3 activity at 24 hr time point. In addition, continuous treatment with MSC induced DNA fragmentation at 34 hr and 48 hr time points with caspase-3 gene expression moderately increased at 16 hr and 24 hr time points. Caspase-6 and -8 were also involved in the MSC-induced apoptosis but to a lesser extent. These results suggest that MSC mediates cleavage of PARP and apoptosis by activating one or more caspases in synchronized TM6 cells and the events are dependent on the duration of treatment.

Animals↗
PubMed2001

Effect of 7beta-hydroxycholesterol on cellular redox status and heat shock protein 70 expression in macrophages.

The proatherogenic effects of oxidized low-density lipoproteins are attributed to oxysterols, particularly 7beta-hydroxycholesterol. In the present study, we have examined the effect of 7beta-hydroxycholesterol on cellular redox status and heat shock protein 70 (hsp70) expression. Murine peritoneal macrophages were incubated for 24 hours with increasing concentrations of 7beta-hydroxycholesterol (0-25 microg/ml). Intracellular reduced glutathione levels decreased and oxidized glutathione levels increased, thus increasing the redox ratio. Hsp70 expression in macrophages decreased in a dose-dependent fashion. It is suggested that 7beta-hydroxycholesterol exerts oxidative stress on macrophages and makes them more susceptible to its proatherogenic effects by impairing the cellular defense system consisting of antioxidants and stress proteins.

Animals↗
PubMed2001

Multiple vasculogenic disabilities : a challenge in rehabilitation.

A 37 year old male presented with left hemiplegia, left below knee amputation, right partial foot amputation and claudication pain. The limitations in the rehabilitation management in such a high-risk patient are multiplied. The appreciable benefits from supervised rehabilitation and judicious goal setting can help in improving the functional status and retard the disease progression in such patients. This study highlights that coexisting cerebrovascular, coronary and peripheral vascular diseases can pose a real challenge and can result in multiple disabilities.

Adult↗
PubMed2001

Cyclin-dependent kinase (cdk) inhibitors/cdk4/cdk2 complexes in early stages of mouse mammary preneoplasia.

The level of circulating ovarian hormones (estrogen and progesterone) alone or in combination with pituitary hormones have a potent mitogenic impact in the normal mammary gland, and they also play a pivotal role in the development and progression of mammary carcinoma. The differential effects of hormones on the molecular components of cyclin-dependent kinase (cdk) complexes in mammary epithelium of the hormone-dependent ductal outgrowth line, EL11, and the hormone-independent alveolar outgrowth line, TM2L, were the focus of this study. The two outgrowth lines, which represent early stages in mammary hyperplasia, were compared with normal mammary gland at different hormonal conditions: control, hormone stimulated by pituitary isograft, and hormone depleted by ovariectomy. Hormonal stimulation by a pituitary isograft resulted in DNA synthesis and lobuloalveolar development of normal mammary ducts, DNA synthesis but no lobuloalveolar development in the EL11 ductal outgrowth, and no changes either in DNA synthesis or in lobuloalveolar morphology in the TM2L outgrowth. The levels of cdk4- and cyclin D1-associated kinase activities were correlated with cell proliferation in only the alveolar phenotypes (i.e., in only hormonally stimulated normal virgin gland and in alveolar mammary outgrowth), whereas cyclin D2-dependent kinase activity was correlated with cell proliferation in only the alveolar preneoplasia. p16(INK4a) and p21(Cip1) protein levels were decreased at the earliest stages of preneoplasia, i.e., at immortalization, and were independent from changes in cyclin D1, which occurred later in preneoplasia. Although all cdk inhibitors changed in concordance with hormonal status reflected by proliferation levels, p27(Kip1) was the only cdk inhibitor that was up-regulated at the earliest stages of preneoplasia and may have a unique role in blocking alveolar differentiation in response to the loss of one or more of the cell cycle-negative regulators. We hypothesize that up-regulation of p27(Kip1) prevents immortalized ductal outgrowths (EL11) from progressing to the neoplastic state, even under hormonal stimulation.

Animals↗
PubMed2001

Influence of 7beta-hydroxycholesterol on glutathione status and nitric oxide production in macrophages: in vitro studies.

Incubation of murine peritoneal macrophages with 7beta-hydroxycholesterol (7beta-OH) for 24 hr led to dose-dependent reduction in cellular glutathione content as well as nitrite levels in the medium. Treatment with an inorganic form of selenium, sodium selenite which is a potent antioxidant, elevated the cellular glutathione levels and decreased nitrite levels. Our results suggest that 7beta-OH may exert its pro-atherogenic effect by inhibiting glutathione synthesis and nitric oxide production by macrophages present in the arterial wall and thus, impair the cellular antioxidant defense system.

Animals↗
PubMed2000

CaCo-2 cells treated with Clostridium perfringens enterotoxin form multiple large complex species, one of which contains the tight junction protein occludin.

The previous model for the action of Clostridium perfringens enterotoxin (CPE) proposed that (i) CPE binds to host cell receptor(s), forming a small ( approximately 90 kDa) complex, (ii) the small complex interacts with other eucaryotic protein(s), forming a large ( approximately 160 kDa) complex, and (iii) the large complex triggers massive permeability changes, thereby inducing enterocyte death. In the current study, Western immunoblot analysis demonstrated that CPE bound to CaCo-2 human intestinal cells at 37 degrees C forms multiple large complex species, with apparent sizes of approximately 200, approximately 155, and approximately 135 kDa. These immunoblot experiments also revealed that occludin, an approximately 65-kDa tight junction protein, is present in the approximately 200-kDa large complex but absent from the other large complex species. Immunoprecipitation studies confirmed that occludin physically associates with CPE in large complex material and also indicated that occludin is absent from small complex. These results strongly suggest that occludin becomes associated with CPE during formation of the approximately 200-kDa large complex. A postbinding association between CPE and occludin is consistent with the failure of rat fibroblast transfectants expressing occludin to bind CPE in the current study. Those occludin transfectants were also insensitive to CPE, strongly suggesting that occludin expression is not sufficient to confer CPE sensitivity. However, the occludin-containing, approximately 200-kDa large complex may contribute to CPE-induced cytotoxicity, because nontoxic CPE point mutants did not form any large complex species. By showing that large complex material is comprised of several species (one containing occludin), the current studies indicate that CPE action is more complicated than previously appreciated and also provide additional evidence for CPE interactions with tight junction proteins, which could be important for CPE-induced pathophysiology.

Animals↗
PubMed2000

Visual outcome following cataract surgery in rural punjab.

In a cluster sample survey in rural areas of Punjab visual outcome after cataract surgery was assessed. Three hundred patients (428 cataract operated eyes) were included in the study from 24 sampled villages. The mean age at cataract extraction was 61.70 +/- 9.82 years. The average interval since the cataract surgery was 7.05 +/- 5.86 years (range 0.11-32 years). Of the 428 operated eyes, 72 (16.82%) were blind (VA < 3/60), 162 (37.85%) had low visual acuity (VA 3/60-< 6/18) and 194 (45.33%) eyes gained good visual acuity (VA > or = 6/18). Cataract surgery related complications were the principal causes leading to blindness in 50 of 72 eyes; these included corneal oedema, (17/72;23.3%), retinal detachment (14/72;19.4%), and aphakic glaucoma (13/72;18.05%). This study emphasizes the need to improve the qualitative aspect of cataract surgery including long-term follow up in rural India.

Aged↗
PubMed1999

Disability and dementia in the emergency department.

The elderly consume medical services in an amount disproportionate to their number. Disability and dementia are commonly underdiagnosed and misunderstood in any emergency department setting. Educating emergency physicians regarding the evaluation of dementia, disability, and abuse is crucial to appropriate management and optimal outcome of these clinical problems.

Activities of Daily Living↗
PubMed1999

Variability in physicochemical and nutritional quality traits of parents, F2 and F3 generations of lentil crosses.

Ten physicochemical and nutritional quality traits (100-seed weight, seed volume, seed density, bulk density, hydration capacity, hydration index, swelling capacity, protein, tryptophan and energy value) were examined in the seed samples of parents, F2 and F3 generations of three microsperma x microsperma and two microsperma x macrosperma crosses of lentils. Significant variation for different traits was observed among the genotypes in both the groups and also among both types of crosses in F2 and F3 generations. Ranges, means and coefficients of variation (CV %) for various traits among parents, F2 and F3 generations of different crosses, along with the deviations between F2 and F3 generation means for various traits in different crosses are discussed. Also suggested is a breeding strategy for evolving lentil varieties with improved seed yield and nutritional quality parameters.

Crosses, Genetic↗
PubMed1999

Nutritional parameters and yield evaluation of newly developed genotypes of lentil (Lens culinaris Medik.).

Among the commonly consumed food legumes, lentils occupy an important place in human nutrition in the Indian subcontinent. Twenty-one lentil genotypes were evaluated for such nutrition related parameters as moisture, protein, crude fiber, fat, ash (total mineral matter), carbohydrates, total energy and metabolizable energy. These genotypes were also analyzed for 100-seed weight and seed yield/plant. Protein content ranged between 22.1 and 27.4% with significant differences among genotypes. Considerable variations were observed among the genotypes for calcium, phosphorus, iron and tannin contents. Large variations existed in yield and 100-seed weight of these genotypes. Seed yield/plant was not significantly correlated with any of the principal seed constituents analyzed in the present study. The genotypes, LH 97 and LH 37 were found to be better and hence could be explored for further development and selection of desirable characteristics.

Animals↗
PubMed1999

Orbital mass lesions: US-guided fine-needle aspiration biopsy--experience in 37 patients.

PURPOSE: To evaluate the safety and effectiveness of using ultrasonographic (US) guidance for performing fine-needle aspiration biopsies of orbital mass lesions. MATERIALS AND METHODS: Thirty-seven patients with mass lesions in the orbit underwent US-guided fine-needle aspiration biopsy. Computed tomographic scans were available in all patients. In 19 patients, the lesions were located in posterior orbit, whereas in 18 patients the lesions were located in (n = 3) or extended up to (n = 15) the anterior compartment. Fine-needle aspiration biopsy was performed with 22-25-gauge needles and use of the freehand technique. RESULTS: Needle biopsies were performed safely and easily, and real-time US monitoring of the needle position was used to avoid injury to the eyeball. No major complications were encountered. Diagnostic specimens were obtained in 29 (78%) of the 37 patients, and 19 benign and 10 malignant disease processes were diagnosed. In eight patients (22%), an appropriate diagnosis could not be made, as aspiration samples yielded insufficient tissue. CONCLUSION: US provides safe and effective guidance for performing fine-needle aspiration biopsy in orbital mass lesions and is especially useful in deep-seated nonpalpable retrobulbar lesions.

Adolescent↗
PubMed1998

The novel core promoter element GAAC in the hgl5 gene of Entamoeba histolytica is able to direct a transcription start site independent of TATA or initiator regions.

Entamoeba histolytica, an enteric protozoa, is the third leading parasitic cause of death worldwide. Investigation of the transcriptional machinery of this eukaryotic pathogen has revealed an unusual core promoter structure that consists of nonconsensus TATA and initiator regions and a novel third conserved core promoter sequence, the GAAC element. Mutation of this region in the hgl5 promoter decreases reporter gene expression and alters the transcription start site. Using positional analysis of this element, we have now demonstrated that it is able to direct a new transcription start site, 2-7 bases downstream of itself, independent of TATA and Inr regions. The GAAC region was also shown to control the rate of transcription via nuclear run on analysis and an amebic nuclear protein was demonstrated to specifically interact with this sequence. This is the first description in the eukaryotic literature of a third conserved core promoter element, distinct from TATA or initiator regions, that is able to direct a transcription start site. We have formulated two models for the role of the GAAC region: (i) the GAAC-binding protein is a part of the TFIID complex and (ii) the GAAC-binding protein functions to "tether" TATA-binding protein to the TATA box.

Animals↗
PubMed1998

Plasma progesterone profiles and fertility status of anestrus Zebu cattle treated with norgestomet-estradiol-eCG regimen.

Zebu cattle are notorious for poor fertility characterized by late maturity and long intercalving intervals attributed to a variety of factors, including genetic, nutritional and climatic. The aim of the present investigation, therefore, was to induce fertile estrus in acyclic pubertal heifers and postpartum anestrous Zebu cows by hormonal intervention. Pubertal Hariana and Sahiwal anestrous heifers (n = 51) and postpartum cows (n = 55) were either assigned a placebo (controls, n = 6 for each breed and parity) or treated with 10-d norgestomet (3 mg) subcutaneous ear implants, with an initial injection of 3 mg, i.m. norgestomet + 5 mg estradiol valerate, followed by 500 IU eCG at implant withdrawal (NOR-treated groups). Jugular venous plasma samples were obtained from a total of 28 animals (controls: 4 heifers and 4 cows; NOR-treated: 12 heifers and 8 cows) on Days 0 (implant insertion), 3, 7, 9 and Day 10 (implant withdrawal), every 12 h on Days 11 and 12, and then once daily on Days 17, 24 and 31. All the samples were assayed for progesterone. Almost all (97%) heifers and 81% cows were induced to estrus, the majority (92% heifers and 79% cows) within 120 h of implant removal. Synchrony of the induced estrus was better in cows, but interval to estrus and estrus duration were significantly longer in heifers (P < 0.05). Post-treatment fertility, based on Day 28 nonreturn rate, first service, and overall conception rates, was better in heifers (78.9, 60.5 and 73.7%, respectively) than cows (77.1, 48.6 and 62.9%, respectively), but the differences were significant only for the overall pregnancy rate (71.8% for heifers and 51.2% for cows; P < 0.05). Low pre-treatment plasma progesterone values (< 0.5 ng/mL) were consistent with ovarian inactivity, confirming the true anestrus status of experimental animals. Controls failed to exhibit estrus and maintained low progesterone concentrations throughout the study. In treated animals, high progesterone values from Day 17 onwards suggested ovulatory estrus. These early luteal phase progesterone concentrations in nonpregnant (P = 0.06) and nonpregnant, nonreturn (P < 0.05) animals were low in comparison with those of pregnant animals. Good fertility resulting from breeding according to estrus, inspite of variable intervals to estrus and estrus duration, advocates its advantage over fixed-time insemination in norgestomet-treated anestrous Zebu cattle.

Anestrus↗