Search PubMed⌕ Search

Biomedical subjects

S P Singh

Publications and source records attributed to S P Singh.

At least 19 recordsLinked to original sources
PubMed2003

Pseudoaneurysm.

Explore the source record for details and available documents.

Aneurysm, False↗
PubMed2002

Measurements of major ion concentration in settled coarse particles and aerosols at a semiarid rural site in India.

Deposition rates and deposition velocities of water-soluble ions (F, Cl, NO3, SO4, NH4, Ca, Mg, Na and K) were measured at a rural site (Gopalpura, Agra). Dry deposition samples were collected throughout the year from December 1995 to August 1997, while the aerosol samples were collected only during the winter season of 1996. Surrogate technique was used to collect the dry deposition samples, while aerosol samples were collected on PTFE membrane filter. Deposition velocities (Vd) of SO4 and NO3 are < or = 0.01 m s(-1) while Ca, Mg, Na, K, NH4, F and Cl exhibit greater than 0.01 m s(-1) Equivalent concentration ratios of K/Na, Ca/Na and Mg/Na conform with the corresponding ratios of local soil, indicating the dominant contribution of local sources. Deposition rates are maximum in winter, followed by summer and monsoon. No significant differences are found in dry deposition rates of all ions or in atmospheric concentrations of soil-derived elements with respect to wind direction. However, in aerosols, concentrations of F, Cl, NO3 and SO4 are higher with winds from southwesterly and westerly directions corresponding to pollution sources located in these directions. Deposition data have been used to calculate the critical load of S and N for soil with respect to Triticum vulgaris. The critical load of actual acidity was found to be 622.4 eq ha(-1) year(-1) within the range of 500-1,000 eq ha(-1) year(-1) as assessed by the RAINS-Asia model for this region. The present load of S and N (77.4 and 86.4 eq ha(-1) year(-1)) was much lower than the critical load of S and N (622.4 and 2,000 eq ha(-1) year(-1)), indicating that at present there is no harmful effect on ecosystem structure and function.

Aerosols↗
PubMed2002

Effects of molybdenum on fertility of male rats.

Sodium molybdate was administered orally to adult male rat at dose level of 10, 30, and 50 mg kg body weight (5 days per week) for 60 days. At higher dose levels significant decrease in absolute and organ-to-body weight ratios of testes, epididymides, seminal vesicles and ventral prostate was observed. The sperm abnormality, associated with decrease in sperm motility and sperm count was also observed. Significant alterations in the activities of marker testicular enzymes, viz. sorbitol dehydrogenase (decreases), lactate dehydrogenase (increases) and gamma-glutamyl transpeptidase (increases) associated with histopathological changes in testes was also observed. Accumulation of molybdenum in testes, epididymides and seminal vesicles was also observed. The study reveals that the oral ingestion of molybdenum may affect the histoarchitecture of testes and sperm morphology. The testicular and spermatotoxic changes may be responsible for observed male mediated developmental toxic effects.

Administration, Oral↗
PubMed2002

Molybdenum in rat tissue.

Male rats were given 50 mg/kg molybdenum (Mo; as sodium molybdate) in drinking water for eight consecutive doses. The feeding of Mo was associated with an increased concentration of Mo in body tissues. The highest concentrations of metal were found in the kidney while it was least in blood cells. The accumulation was considered to be significant.

Administration, Oral↗
PubMed2001

HIV-1 Vpr transactivates LTR-directed expression through sequences present within -278 to -176 and increases virus replication in vitro.

Human immunodeficiency virus type 1 (HIV-1) Vpr, a 14-kDa virion-associated protein, plays an important role in the viral life cycle. Using a panel of truncated HIV-1 LTR-CAT constructs and Vpr expression plasmid, we have identified sequences from nucleotide -278 to -176 in LTR as Vpr-mediated transactivation domain. This region includes the glucocorticoid response element (GRE) in HIV-1 LTR. Transactivation by Vpr was noted with the HIV-1 LTR reporter constructs containing CAT or luciferase. A similar effect was also observed with a construct in which the GRE motif was linked to CAT. Studies involving Vpr mutants identified that helical domains I and III, and amino acid residues at G75 and C76, are responsible for GRE-mediated LTR transactivation. The transactivation function of Vpr is independent of its cell cycle arrest activity. Further, viral replication studies indicated that Vpr-mediated increase in viral replication is directly correlated with the ability of Vpr to transactivate HIV-1 LTR. The results presented here demonstrate that Vpr activates HIV-1 LTR through the host GR pathway and suggest that an intact GRE in the LTR is critical for Vpr activity.

Gene Products, vpr↗
PubMed2001

Virion-associated HIV-1 Vpr: variable amount in virus particles derived from cells upon virus infection or proviral DNA transfection.

Human immunodeficiency virus type-1 (HIV-1) Vpr is a virion-associated protein implicated to have a role in AIDS pathogenesis. In regard to the amount of Vpr incorporated into virus particles, the published data vary widely. To address this, we quantitated Vpr in virus particles derived from diverse sources that are used to evaluate the biological effect of Vpr. Virus particles from infected cells showed only a small amount of Vpr. Interestingly, virus particles from cells cotransfected with HIV-1 proviral DNA lacking Vpr coding sequences (NLDeltaVpr) and a Vpr expression plasmid showed a drastic increase (29.4-fold) in the incorporation of Vpr. Furthermore, cotransfection involving NLDeltaVpr and different concentrations of Vpr expression plasmid resulted in virus particles containing Vpr in proportion to the Vpr expression plasmid used. The differences in virus particles with respect to Vpr as revealed by these studies should be taken into account in assessing the effect of Vpr.

Cell Line↗
PubMed2001

Two distinct 4-hydroxynonenal metabolizing glutathione S-transferase isozymes are differentially expressed in human tissues.

The two previously reported human glutathione S-transferase isozymes, hGST5.8 and hGSTA4-4, have been suggested to be similar because of their comparable activities toward 4-hydroxynonenal-GSH conjugation. Here, we demonstrate that hGST5.8 and hGSTA4-4 are distinct. Antibodies raised against hGSTA4-4 did not recognize hGST5.8, and antibodies raised against mouse GSTA4-4 that cross-react with hGST5.8 did not recognize hGSTA4-4. The pI value of hGSTA4-4 was found to be 8.4, as opposed to the pI value of 5.8 for hGST5.8. The two isozymes are differentially expressed in human tissues and there are significant differences in their kinetic properties. While both isozymes showed a strong expression in liver and testis, hGSTA4-4 was not detected in brain where hGST5.8 was present. In the pancreas, a strong expression of hGST5.8 was observed while hGSTA4-4 was barely detectable in this tissue.

Aldehydes↗
PubMed2001

The attitudes of 'tomorrow's doctors' towards mental illness and psychiatry: changes during the final undergraduate year.

AIMS: To compare the efficacy of two teaching styles, didactic teaching and problem based learning, in producing enduring change in final-year medical students' attitudes towards psychiatry and mental illness. METHOD: A 1-year follow-up questionnaire survey of two groups of medical students taught psychiatry in their fourth-year training by two different methods. One-year follow-up scores were compared with pre-attachment and post-attachment scores in the fourth year. RESULTS: 70 (68%) students completed both questionnaires at follow-up. The follow-up scores were significantly lower compared with both the fourth-year pre-attachment and post-attachment scores, suggesting that the positive change in attitudes following psychiatric training in the fourth year significantly decayed during the final year. The two teaching methods did not differ in the magnitude of this reduction. CONCLUSIONS: The positive change that occurs in medical students' attitude towards psychiatry, psychiatrists and mental illness after their fourth-year psychiatric training is transient and decays over the final year.

Attitude↗
PubMed2001

Construct design for efficient, effective and high-throughput gene silencing in plants.

Post-transcriptional silencing of plant genes using anti-sense or co-suppression constructs usually results in only a modest proportion of silenced individuals. Recent work has demonstrated the potential for constructs encoding self-complementary 'hairpin' RNA (hpRNA) to efficiently silence genes. In this study we examine design rules for efficient gene silencing, in terms of both the proportion of independent transgenic plants showing silencing, and the degree of silencing. Using hpRNA constructs containing sense/anti-sense arms ranging from 98 to 853 nt gave efficient silencing in a wide range of plant species, and inclusion of an intron in these constructs had a consistently enhancing effect. Intron-containing constructs (ihpRNA) generally gave 90-100% of independent transgenic plants showing silencing. The degree of silencing with these constructs was much greater than that obtained using either co-suppression or anti-sense constructs. We have made a generic vector, pHANNIBAL, that allows a simple, single PCR product from a gene of interest to be easily converted into a highly effective ihpRNA silencing construct. We have also created a high-throughput vector, pHELLSGATE, that should facilitate the cloning of gene libraries or large numbers of defined genes, such as those in EST collections, using an in vitro recombinase system. This system may facilitate the large-scale determination and discovery of plant gene functions in the same way as RNAi is being used to examine gene function in Caenorhabditis elegans.

Arabidopsis↗
PubMed2001

Catalytic function of Drosophila melanogaster glutathione S-transferase DmGSTS1-1 (GST-2) in conjugation of lipid peroxidation end products.

Drosophila melanogaster glutathione S-transferase DmGSTS1-1 (earlier designated as GST-2) is related to sigma class GSTs and was previously described as an indirect flight muscle-associated protein with no known catalytic properties. We now report that DmGSTS1-1 isolated from Drosophila or expressed in Escherichia coli is essentially inactive toward the commonly used synthetic substrate 1-chloro-2,4-dinitrobenzene (CDNB), but has relatively high glutathione-conjugating activity for 4-hydroxynonenal (4-HNE), an electrophilic aldehyde derived from lipid peroxidation. 4-HNE is thought to have signaling functions and, at higher concentrations, has been shown to be cytotoxic and involved in the etiology of various degenerative diseases. Drosophila strains carrying P-element insertions in the GstS1 gene have a reduced capacity for glutathione conjugation of 4-HNE. In flies with both, one, or none of the GstS1 alleles disrupted by P-element insertion, there is a linear correlation between DmGSTS1-1 protein content and 4-HNE-conjugating activity. This correlation indicates that in adult Drosophila 70 +/- 6% of the capacity to conjugate 4-HNE is attributable to DmGSTS1-1. The high abundance of DmGSTS1-1 (approximately 2% of the soluble protein in adult flies) and its previously reported localization in tissues that are either highly aerobic (indirect flight muscle) or especially sensitive to oxidative damage (neuronal tissue) suggest that the enzyme may have a protective role against deleterious effects of oxidative stress. Such function in insects would be analogous to that carried out in mammals by specialized alpha class glutathione S-transferases (e.g. GSTA4-4). The independent emergence of 4-HNE-conjugating activity in more than one branch of the glutathione S-transferase superfamily suggests that 4-HNE catabolism may be essential for aerobic life.

Aldehydes↗
PubMed2001

Intracellular nickel accumulation by Pseudomonas aeruginosa and its chemical nature.

AIMS: To investigate intracellular localization of nickel and its chemical nature in Pseudomonas aeruginosa. METHODS AND RESULTS: Transmission electron micrographs of Ni-loaded bacteria exhibited a darkened electron opaque zone throughout the cell periphery. Energy dispersive X-ray analysis confirmed the deposition of metallic nickel. Cell fractionation revealed that 88% of the accumulated nickel was restricted to the periplasm and membrane. X-ray diffraction patterns ascertained the chemical nature of cellular Ni as phosphide (Ni5P4, NiP2 and Ni12P5) and carbide (Ni3C) crystals. CONCLUSION: Pseudomonas aeruginosa accumulated nickel as its phosphide and carbide crystal mostly in the cell envelope region, indicating the predominant role of phosphoryl and carboxyl/carbonyl groups of cell wall/membrane components in cation sequestration. SIGNIFICANCE AND IMPACT OF THE STUDY: The data contribute significantly to a better understanding of bacteria-metal interaction and will be useful in developing biotechnological strategies for toxic metal bioremediation.

Biodegradation, Environmental↗
PubMed2001

Pryce's type I pulmonary intralobar sequestration presenting with massive hemoptysis.

Pryce's type I intralobar sequestration, in which a region of lung exhibits tracheobronchial continuity and aberrant systemic arterial supply, is most frequently asymptomatic and discovered incidentally. While hemoptysis may be a common presenting symptom, massive hemoptysis is rarely seen. We document a case of a 58-year-old man, previously asymptomatic, whose initial presentation was that of massive hemoptysis. The radiographic, intraoperative and pathologic findings in our patient confirm that his sequestration was of Pryce's type I. Ann Diagn Pathol 5:91-95, 2001.

Angiography↗
PubMed2001

Pleural amyloidosis mimicking mesothelioma: a clinicopathologic study of two cases.

Two cases of pleural amyloidosis are presented. The patients are two men, 70 and 72 years of age respectively. Neither patient had evidence of systemic amyloidosis. Each presented clinically with symptoms of chest pain and dyspnea. Radiologically, both patients showed diffuse pleural thickening similar to that observed in malignant mesothelioma. In both patients, surgical decortication of the pleura was performed. Histologically, the lesions were characterized by the presence of an amorphous eosinophilic material with focal collections of a lymphoplasmacytic infiltrate. Focal clusters of giant cells were admixed with the lymphoplasmacytic infiltrate. Histochemical stains for Congo red showed strong positive apple-green birefringency. Immunohistochemical studies using kappa and lambda light chains showed polyclonality. The cases discussed herein represent an unusual presentation of amyloid and one that needs to be considered in the differential diagnosis of malignant mesothelioma.

Aged↗