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Biomedical subjects

V Sharma

Publications and source records attributed to V Sharma.

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

Road-traffic accidents--a demographic and topographic analysis.

Injuries and fatalities occur in all forms of transportation, but numerically, road-traffic accidents account for the great majority worldwide. There is little that the autopsy surgeon can contribute to the elucidation of factors leading to the accident as it is largely the circumstantial and forensic laboratory evidence which is likely to reveal a non-accidental cause. However, the doctor's role in detecting the compatibility/incompatibility of the injuries with those usually sustained in traffic accidents (to detect any which are 'atypical', e.g. focal depressed fracture of the skull), distinguishing antemortem from postmortem injuries, demonstrating the presence of any disease capable of creating sudden incapacity and analysing samples for alcohol/drugs, etc., can go a long way in assigning roles to the human and to some extent vehicular and environmental factors. This warrants that a meticulous autopsy be conducted and not merely a catalogue of injuries. It must be appreciated that a fatal accident is likely to result in litigation and the extent of litigation cannot be anticipated at the time of the autopsy. One must, therefore, aim at the close study of any accident victim and a careful assessment of the case is always rewarding. The present study was undertaken in the Department of Forensic Medicine at (a) Government Medical College, Jammu (1991-93), (b) Mulana Azad Medical College, New Delhi (1993-95) and (c) Government Medical College, Chandigarh (1994-June 2000), with the object of doing a comparative analysis of the various aspects of the road-traffic accidents and accidental deaths in three topographically and demographically different cities in India and to suggest remedial measures to bring down the accident rate.

Accidents, Traffic↗
PubMed2001

The effect of electroconvulsive therapy on suicide risk in patients with mood disorders.

OBJECTIVE: To discuss the effect of electroconvulsive therapy (ECT) on suicide risk in patients with mood disorders. METHOD: A review of the available data on the short-term and long-term effects of ECT on suicide mortality among patients with mood disorders. CONCLUSION: ECT has an acute but not a long-term beneficial effect on suicidality. Due to the significant limitations of studies in this area, however, the data need to be interpreted with caution.

Antidepressive Agents↗
PubMed2000

Study of charmless hadronic B meson decays to pseudoscalar-vector final states.

We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated.

Journal Article↗
PubMed2000

Radiation therapy in T1-T2 glottic carcinoma: influence of various treatment parameters on local control/complications.

PURPOSE: To evaluate the influence of various treatment parameters on local control as well as complications in T1 and T2 glottic carcinomas. METHODS AND MATERIALS: Between 1975 and 1989, 676 patients with early glottic carcinoma (460 T1 and 216 T2) received curative radiation with three different treatment regimens, as follows: Regimen 1-50 Gy/15 Fr/3 weeks (3.33 Gy/daily) for 192 patients; Regimen 2-60-62.5 Gy/24-25 Fr/5 weeks (2.5 Gy/daily) for 352 patients; and Regimen 3-55-60 Gy/25-30 Fr/5-6 weeks (2-2.25 Gy/daily) for 132 patients. RESULTS: The local control at 10 years was 82% and 57% for T1 and T2 lesions respectively (p = 0.0). For the T1N0M0 group, field size had significant impact on local control with both univariate (p = 0.05) and multivariate (p = 0.03) analysis. For T2N0M0, group field size (p = 0.03) as well as registration year (p = 0.016) were significant in univariate analysis whereas only field size remained significant on multivariate analysis. Persistent radiation edema was noted in 146 (22%) patients and was significantly worse with larger field size (p = 0.000) but not related to different treatment regimens. CONCLUSION: The shorter fractionation schedule had comparable local control, without increased complications in comparison to the protracted schedule and is best suited for a busy department.

Adult↗
PubMed2000

Observation of B --> K(+/-) pi(0) and B --> (K)0 pi(0), and evidence for B --> pi(+)pi(-).

We have studied charmless hadronic decays of B mesons into two-body final states with kaons and pions and observe three new processes with the following branching fractions: beta(B-->pi(+)pi(-)) = (4.3(+1. 6)(-1.4)+/-0.5)x10(-6), beta(B-->K(0)pi(0)) = (14.6(+5.9+2.4)(-5.1-3. 3))x10(-6), and beta(B-->K(+)/-pi(0)) = (11.6(+3.0+1.4)(-2.7-1.3))x10(-6). We also update our previous measurements for the decays B-->K(+)/-pi(-/+) and B+/--->K(0)pi(+/-).

Journal Article↗
PubMed2000

Human T-cell lymphotropic virus type-I tax gene induces interleukin-8 secretion by autocrine mechanism and has No effect on interleukin-16 in transfected Jurkat cells.

Human T-cell lymphotropic virus I (HTLV-I) Tax has been shown to transactivate several cellular genes. In this study, we show that interleukin-8 (IL-8) is expressed and secreted in tax-transfected Jurkat cells that were further augmented by mitogen stimulation. Expression of high-affinity IL-8-R (Type A) mRNA in these cells suggests an autocrine role for this chemokine in HTLV-I-infected T-cells. However, interleukin-16 (IL-16) mRNA expression or protein secretion was not significantly modulated either constitutively or even upon mitogen stimulation in these tax-transfected cells.

Base Sequence↗
PubMed2000

Search for CP violation in B+/- --> J/psiK+/- and B+/- --> psi(2S)K+/- decays.

We present a search for direct CP violation in B+/--->J/psiK+/- and B+/--->psi(2S)K+/- decays. In a sample of 9.7x10(6) B&Bmacr; meson pairs collected with the CLEO detector, we have fully reconstructed 534 B+/--->J/psiK+/- and 120 B+/--->psi(2S)K+/- decays with very low background. We have measured the CP-violating charge asymmetry to be [+1.8+/-4.3(stat)+/-0.4(syst)]% for B+/--->J/psiK+/- and [+2.0+/-9. 1(stat)+/-1.0(syst)]% for B+/--->psi(2S)K+/-.

Journal Article↗
PubMed2000

The primary structure of the acidic lectin from winged bean (Psophocarpus tetragonolobus): insights in carbohydrate recognition, adenine binding and quaternary association.

The amino acid sequence of the winged bean acidic lectin (WBA II) was determined by chemical means and by recombinant techniques. From the N- and C-terminal sequence, obtained chemically, primers were designed for PCR amplification of the genomic DNA. The PCR product was cloned and sequenced to get the complete primary structure of WBA II. Peptide fragments for sequencing were also obtained by tryptic cleavages of the native lectin. The WBA II sequence showed a high degree of homology with that of WBA I and Erythrina corallodendron lectin (ECorL), especially in the regions involved in subunit association, where there is a very high conservation of residues. This perhaps implies the importance of this particular region in subunit interactions in this lectin. In addition, many of the residues, involved in carbohydrate binding in legume lectins, appear to be conserved in WBA II. The distinct differences in anomeric specificity observed amongst WBA I, WBA II, ECorL and peanut agglutinin (PNA) may be explained by subtle differences in sequence/structure of their D-loops. WBA II binds adenine quite strongly; a putative adenine binding sequence has been identified.

Adenine↗
PubMed2000

Ascorbic acid in idiopathic recurrent calcium urolithiasis in humans--does it have an abettor role in oxalate, and calcium oxalate crystallization?

The role of ascorbic acid (ASC) in the pathophysiology of renal calcium stones is not clear. We evaluated ASC in blood and urine of fasting male patients with idiopathic calcium urolithiasis (ICU) and healthy volunteers. Using smaller subgroups, we also evaluated their response to exogenous ASC [either intravenous or oral ASC (5 mg/kg bodyweight)] administered together with an oxalate-free test meal. The influence of ASC on calcium oxalate crystallization, the morphology of crystals at urinary pH 5, 6 and 7, and the effect of increasing duration of urine incubation on urinary oxalate at these pHs, without and with addition of ASC, were studied too. In normo- and hypercalciuric ICU, blood and urinary ASC from fasting patients remained unchanged, but the slope of the regression line of urinary ASC versus urinary oxalate was steeper than in the controls; the plasma ASC half-life did not differ between controls, normo- and hypercalciuric ICU; the ASC-supplemented meal caused an increase in the integrated plasma oxalate in the normocalciuric subgroup versus controls. In normo- and hypercalciuric ICU urinary oxalate, the oxalate/glycolate ratio, and calcium oxalate supersaturation were increased, but urinary glycolate was unchanged. In the controls, oral ASC did not affect calcium oxalate crystallization, while in ICU, ASC inhibited crystal growth. In control urine calcium oxalate dihydrate and calcium oxalate monohydrate develops, while in ICU urine only the former crystal type develops. In vitro oxalate neoformation from ASC did not occur. It was concluded that (1) under normal conditions an abettor role of ASC for renal stones is not recognizable, (2) in ICU, urinary oxalate excess unrelated to degradation of exogenous ASC is exhibited, and that this is most likely unrelated to an initial increase in oxalate biosynthesis, and (3) ASC appears to modulate directly calcium oxalate crystallization in ICU, although the true mode of action is still not known.

Administration, Oral↗
PubMed2000

Nephrocalcinosis and hyperlipidemia in rats fed a cholesterol- and fat-rich diet: association with hyperoxaluria, altered kidney and bone minerals, and renal tissue phospholipid-calcium interaction.

To determine whether an "atherogenic" diet (excess of cholesterol and neutral fat) induces pathological calcification in various organs, including the kidney, and abnormal oxalate metabolism, 24 male Sprague-Dawley rats were fed either normal lab chow (controls, n = 12) or the cholesterol- and fat-rich experimental diet (CH-F, n = 12) for 111 +/- 3 days. CH-F rats developed dyslipidemia [high blood levels of triglycerides, total, low-density lipoprotein (LDL)-, very low-density lipoprotein (VLDL)-, high-density lipoprotein (HDL)-bound cholesterol, total phospholipids], elevated serum total alkaline phosphatase and lactate dehydrogenase (LDH) levels, in the absence of changes in overall renal function, extracellular mineral homeostasis [serum protein-corrected total calcium, magnesium, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25(OH)2D)], plasma glycolate and oxalate levels. There was a redistribution of bone calcium and enhanced exchange of this within the extraosseous space, which was accompanied by significant bone calcium loss, but normal bone histomorphometry. Liver oxalate levels, if expressed per unit of defatted (DF) dry liver, were three times higher than in the controls. Urinary glycolate, oxalate, calcium and total protein excretion levels were elevated, the latter showing an excess of proteins > 100 kD and a deficit of proteins > 30-50 kD. Urinary calcium oxalate supersaturation was increased, and calcium phosphate supersaturation was unchanged. There were dramatically increased (by number, circumference, and area) renal calcium phosphate calcifications in the cortico-medullary region, but calcium oxalate deposits were not detectable. Electron microscopy (EM) and elemental analysis revealed intratubular calcium phosphate, apparently needle-like hydroxyapatite. Immunohistochemistry of renal tissue calcifications revealed co-localization of phospholipids and calcium phosphate. It is concluded that rats fed the CH-F diet exhibited: (1) a spectrum of metabolic abnormalities, the more prominent being dyslipidemia, hyperoxaluria, hypercalciuria, dysproteinuria, loss of bone calcium, and calcium phosphate nephrocalcinosis (NC); and (2) an interaction between calcium phosphate and phospholipids at the kidney level. The biological significance of these findings for the etiology of idiopathic calcium urolithiasis in humans is uncertain, but the presented animal model may be helpful when designing clinical studies.

Absorptiometry, Photon↗
PubMed2000

Glutathione depletion leads to delayed growth stasis in Saccharomyces cerevisiae: evidence of a partially overlapping role for thioredoxin.

Disruption of the first enzyme of glutathione biosynthesis in both Saccharomyces cerevisiae and Schizosaccharomyces pombe leads to a glutathione auxotrophy phenotype on plates. However, growth experiments in liquid medium revealed that the cessation of growth resulting from glutathione depletion in these yeasts is very delayed in S. cerevisiae compared to S. pombe. Glutathione metabolism was investigated to understand this delayed growth stasis in S. cerevisiae. The assimilation of reduced and oxidized glutathione, the intracellular storage pools of glutathione and the turnover of this compound were investigated and found to be similar in both yeasts. A possible overlapping role of intracellular thioredoxin in causing delayed stasis was studied. Yeast thioredoxin was overexpressed in S. cerevisiae and was found to partially relieve the dependence of S. cerevisiae glutathione auxotrophs on extracellular glutathione in glucose-grown cultures, as well as in glycerol-grown cultures where conditions of increased glutathione requirements exists in the cell. By partially, but not completely, compensating for glutathione deficiency in this yeast, thioredoxin thus appeared to be the major factor that was causing the delayed growth stasis following glutathione depletion in this yeast.

Culture Media↗
PubMed2000

Dendritic cells armed with anti-CD3 mAbs reduce pulmonary metastases, prolong survival, and engender antitumor effector cells demonstrable by adoptive transfer.

BACKGROUND: Dendritic cells (DCs) pulsed with tumor cells or peptides are effective antitumor agents in a number of tumor models. In light of our earlier demonstration that T-cell signaling via the CD3 proteins induces cytolytic activity and constrains tumor progression, we equipped DCs pulsed with tumor cells with anti-CD3 mAbs and tested their antitumor efficacy in a murine renal cell cancer pulmonary metastasis model. METHODS: We investigated the antitumor efficacy of DCs pulsed with whole irradiated tumor cells (DC/R) or DCs pulsed with irradiated tumor cells and armed with anti-CD3 mAbs (DC/R/anti-CD3 mAbs). Experimental end points included the number of pulmonary metastases and survival of tumor-inoculated mice. RESULTS: Our studies demonstrate that arming tumor-pulsed DCs with anti-CD3 mAbs results in a superior outcome compared to that from tumor-pulsed DCs alone in terms of reduction in the number of pulmonary metastases and survival times. Furthermore, adoptive transfer experiments revealed that the splenocytes from DC/R/anti-CD3 mAbs-treated mice are superior to splenocytes from DC/R-treated mice in reducing renal cancer pulmonary metastases in severe combined immunodeficient (SCID) beige mice. CONCLUSION: Our data suggest that the therapeutic efficacy of DCs pulsed with tumor cells can be augmented by arming them with anti-CD3 mAbs. DC-based treatment regimens that currently are being pursued in clinical trials might be improved by equipping such cells with anti-CD3 mAbs.

Adoptive Transfer↗
PubMed2000

Detecting disorder in spatial vision.

In normal foveal vision, visual space is accurately mapped from retina to cortex. However, the normal periphery, and the central field of strabismic amblyopes have elevated position discrimination thresholds, which have often been ascribed to increased 'intrinsic' spatial disorder. In the present study we evaluated the sensitivity of the human visual system (both normal and amblyopic) to spatial disorder, and asked whether there is increased 'intrinsic' topographical disorder in the amblyopic visual system. Specifically, we measured thresholds for detecting disorder (two-dimensional Gaussian position perturbations) either in a horizontal string of N equally spaced samples (Gabor patches), or in a ring of equally spaced samples over a wide range of feature separations. We also estimated both the 'equivalent intrinsic spatial disorder' and sampling efficiency using an equivalent noise approach. Our results suggest that both thresholds for detecting disorder, and equivalent intrinsic disorder depend strongly on separation, and are modestly increased in strabismic amblyopes. Strabismic amblyopes also show markedly reduced sampling efficiency. However, neither amblyopic nor peripheral vision performs like ideal or human observers with added separation-independent positional noise. Rather, the strong separation dependence suggests that the 'equivalent intrinsic disorder' may not reflect topographic disorder at all, but rather may reflect an abnormality in the amblyopes' Weber relationship.

Adolescent↗
PubMed2000

A note on suicidal deterioration with recovered memory treatment.

BACKGROUND: Many patients who have been told they have Multiple Personality/Dissociative Identity Disorder (MPD/DID) seem to have deteriorated clinically after being so diagnosed. We report here the results of a survey of suicide attempts in patients diagnosed as having MPD and a comparison group hospitalized with a mood disorder. METHODS: Twenty individuals who had been diagnosed as having MPD, had developed false memories, and had relinquished them, were surveyed with respect to suicide attempts before and after the diagnosis. Twelve of those approached agreed to provide data and were compared with 12 patients from an in-patient mood disorders unit, matched for age and sex. RESULTS: In the MPD group more patients attempted suicide after being diagnosed than before and they made more separate attempts at suicide than before. The reverse was true in the comparison group with patients and suicide attempts before and after hospitalization. Comparing the numbers of attempts in the groups before diagnosis/hospitalization and afterward Chi(2)=20.177, DF=1, P<0.001. LIMITATIONS AND CONCLUSIONS: Both samples were highly selected, and the comparison group does not provide an exact control. Nevertheless, the results support a trend in the literature that finds the diagnosis of multiple personality disorder and the use of recovered memory treatment are harmful.

Adult↗
PubMed2000

Novel gallium(III) complexes transported by MDR1 P-glycoprotein: potential PET imaging agents for probing P-glycoprotein-mediated transport activity in vivo.

BACKGROUND: Multidrug resistance (MDR) mediated by expression of MDR1 P-glycoprotein (Pgp) represents one of the best characterized barriers to chemotherapy in cancer patients. Positron emission tomography (PET) agents for analysis of Pgp-mediated drug transport activity in vivo would enable noninvasive assessment of chemotherapeutic regimens and MDR gene therapy. RESULTS: Candidate Schiff-base phenolic gallium(III) complexes were synthesized from their heptadentate precursors and gallium(III)acetylacetonate. Crystal structures demonstrated a hexacoordinated central gallium with overall trans-pseudo-octahedral geometry. Radiolabeled (67)Ga-complexes were obtained in high purity and screened in drug-sensitive (Pgp(-)) and MDR (Pgp(+)) tumor cells. Compared with control, lead compound 6. demonstrated antagonist-reversible 55-fold lower accumulation in Pgp-expressing MDR cells. Futhermore, compared with wild-type control, quantitative pharmacokinetic analysis showed markedly increased penetration and retention of 6. in brain and liver tissues of mdr1a/b((-/-)) gene disrupted mice, correctly mapping Pgp-mediated transport activity at the capillary blood-brain barrier and hepatocellular biliary cannalicular surface in vivo. CONCLUSIONS: These results indicate that gallium(III) complex 6. is recognized by MDR1 Pgp as an avid transport substrate, thereby providing a useful scaffold to generate (68)Ga radiopharmaceuticals for molecular imaging of Pgp transport activity in tumors and tissues in vivo using PET.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Structure-function modeling of the interactions of N-alkyl-N-hydroxyanilines with rat hepatic aryl sulfotransferase IV.

Although previous investigations have clearly shown that N-hydroxy arylamines and N-hydroxy heterocyclic amines are substrates for sulfotransferases, relatively little is known about which structural features of the N-hydroxy arylamines are important for sulfation to occur. The purpose of this investigation was to determine the extent to which secondary N-alkyl-N-hydroxy arylamines interact with aryl sulfotransferase (AST) IV (also known as tyrosine-ester sulfotransferase or ST1A1) and to evaluate these interactions using molecular modeling techniques. AST IV is a major cytosolic sulfotransferase in the rat, and it catalyzes the sulfation of various phenols, benzylic alcohols, arylhydroxamic acids, oximes, and primary N-hydroxy arylamines. In this study, three secondary N-hydroxy arylamines, N-hydroxy-N-methylaniline, N-ethyl-N-hydroxyaniline, and N-hydroxy-N-n-propylaniline, were found to be substrates for the purified rat hepatic AST IV. However, when the N-alkyl substituent was an n-butyl group (i.e., N-n-butyl-N-hydroxyaniline), the interaction with the enzyme changed from that of a substrate to competitive inhibition. This change in specificity was further explored through the construction and use of a model for AST IV based on mouse estrogen sulfotransferase, an enzyme whose crystal structure has been previously determined to high resolution. Molecular modeling techniques were used to dock each of the above N-hydroxy arylamines into the active site of the homology model of AST IV and determine optimum ligand geometries. The results of these experiments indicated that steric constraints on the orientation of binding of secondary N-alkyl-N-hydroxy arylamines at the active site of AST IV play a significant role in determining the nature of the interaction of the enzyme with these compounds.

Aminophenols↗