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Biomedical subjects

A Gupta

Publications and source records attributed to A Gupta.

At least 91 records · Page 5Linked to original sources
PubMed2005

Megaloblastosis: from morphos to molecules.

OBJECTIVE: Megaloblastosis (i.e., megaloblastic transformation of erythroid precursor cells in the bone marrow) is the cytomorphological hallmark of megaloblastic anemia resulting from vitamin B12 and folate deficiency. It is characterized by a finely stippled lacy pattern of nuclear chromatin, which is believed to be an expression of deranged cellular DNA synthesis. However, the molecular basis of these cytomorphological aberrations still remains obscure. The current presentation describes the results of our studies on some molecular events associated with the development of megaloblastosis. METHODS: Transmission electron microscopy was used to study megaloblasts as well as DNA fibers extracted from megaloblastic and normoblastic bone marrows with and without treatment with proteinase K during the extraction procedure; cellular DNA synthesis in bone marrow cultures was studied by incorporation of 3H-thymidine and deoxyuridine suppression test, while histone biosynthesis in bone marrow cells was studied by in vitro incorporation of 3H-tryptophan, 3H-lysine and 3H-arginine into histones. RESULTS: Derangement of DNA synthesis occurred due to an impaired de novo pathway of thymidylate synthesis in both vitamin-B12- and folate-deficient human megaloblastic bone marrows as well as in the bone marrows of rhesus monkeys and rats with experimentally induced folate deficiency. Interestingly, folate-deficient monkeys developed frank megaloblastic bone marrows, but folate-deficient rats did not. On the other hand, megaloblastic changes in the bone marrow of human patients with myelodysplastic syndrome and erythroleukemia were not associated with this DNA synthetic abnormality. Biosynthesis of predominantly arginine-rich histones in megaloblastic bone marrows was markedly reduced as compared to normoblastic bone marrows, which was consistently associated with elongation and despiralization of chromosomes and finely stippled nuclear chromatin in megaloblasts. CONCLUSION: The impaired biosynthesis of predominantly arginine-rich nuclear histones appeared to be a common molecular event (a denominator) underlying the development of megaloblastosis with or without abnormal DNA synthesis.

Adolescent↗
PubMed2005

An international outbreak of salmonellosis associated with raw almonds contaminated with a rare phage type of Salmonella enteritidis.

During the winter of 2000 to 2001, an outbreak due to Salmonella Enteritidis (SE) phage type 30 (PT30), a rare strain, was detected in Canada. The ensuing investigation involved Canadian and American public health and food regulatory agencies and an academic research laboratory. Enhanced laboratory surveillance, including phage typing and pulsed-field gel electrophoresis, was used to identify cases. Case questionnaires were administered to collect information about food and environmental exposures. A case-control study with 16 matched case-control pairs was conducted to test the hypothesis of an association between raw whole almond consumption and infection. Almond samples were collected from case homes, retail outlets, and the implicated processor, and environmental samples were collected from processing equipment and associated farms for microbiological testing. One hundred sixty-eight laboratory-confirmed cases of SE PT30 infection (157 in Canada, 11 in the United States) were identified between October 2000 and July 2001. The case-control study identified raw whole almonds as the source of infection (odds ration, 21.1; 95% confidence interval, 3.6 to infinity). SE PT30 was detected in raw whole natural almonds collected from home, retail, distribution, and warehouse sources and from environmental swabs of processing equipment and associated farmers' orchards. The frequent and prolonged recovery of this specific organism from a large agricultural area was an unexpected finding and may indicate significant diffuse contamination on these farms. Identification of almonds as the source of a foodborne outbreak is a previously undocumented finding, leading to a North American recall of this product and a review of current industry practices.

Adolescent↗
PubMed2005

Photooxidation of acyclovir in aqueous solution.

Photodegradation of an aqueous solution of acyclovir in phosphate buffer (pH 7) under aerobic conditions was studied with light of wavelength > 270 nm. Three major products were isolated and identified on the basis of IR, NMR and mass spectral studies. The products are: (2-hydroxyethoxy)methyl spiroiminodihydantoin (2), (2-hydroxyethoxy)methyl(amino)-2-imino-1,2-dihydroimidazole-5-one (3), and 2,2-diamino-4-[(2-hydroxyethoxy)methyl]amino)-5-[2H]-oxazolone (4). Furthermore the effects of D2O as reaction medium, addition of sodium azide and absence of oxygen on the photodegradation of acyclovir were examined, the observations indicating the involvement of singlet oxygen. The formation of the products is explained by the photooxidation of acyclovir.

Acyclovir↗
PubMed2005

Clinical characteristics of patients with multiple system atrophy in Singapore.

INTRODUCTION: Our study aimed to describe the clinical features of multiple system atrophy (MSA) in Singapore and verify its diagnosis using the consensus statement in the diagnosis of MSA. MATERIALS AND METHODS: All patients suspected to have MSA between 1995 and March 2005 were identified from the Movement Disorders database and the autonomic function testing results. The medical records were reviewed using a standardised data collection form. The diagnosis of MSA was verified using the consensus statement. Disease progression was evaluated using 2 pre-determined events: aid-requiring walking and wheelchair use. RESULTS: Seventy-two per cent (33/46) fulfilled the consensus statement. There were 85% Chinese, 9% Malays, and 6% Indians. The mean age at onset of the disease was 60 +/- 10 years. We found a predominance of males (M:F = 1.5:1) as well as MSA-C cases (67%). The most common initial presenting features were parkinsonism and cerebellar signs (27% each). Abnormal neuroimaging was seen in 29 patients (91%). Autonomic function testing was abnormal in 58% (7/12). The risk for aid-requiring walking and wheelchair use at 3 years from onset of the disease was 31% and 17%, respectively. By 5 years, this had increased to 45% and 30%, respectively. There was no difference in the events rate between MSA subtypes. CONCLUSIONS: The clinical characteristics of MSA in Singapore are presented. Our study revealed a predominance of MSA-C patients as well as a later age at onset of disease and longer median time to aid-requiring walking and wheelchair use compared to Japanese patients.

Adult↗
PubMed2005

Histopathological changes in cases of aluminium phosphide poisoning.

Of a total of 205 poisoning deaths in our hospital in 2003, 83 cases were due to Aluminium phosphide poisoning and were further analyzed. Most vulnerable age group was 21-40 years and M:F ratio was 2:1. On naked eye examination, almost all the vital organs were found to be congested. On microscopic study, the liver showed central venous congestion, degeneration, haemorrhage, sinusoidal dilation, bile stasis, centrilobular necrosis, Kupffer cell hyperplasia, infiltration by mononuclear cells and fatty change. Microscopy of the lungs revealed alveolar thickening, oedema, dilated capillaries, collapsed alveoli and haemorrhage. In the kidney, changes were degeneration, infiltration, tubular dilation and cloudy swelling. Changes in the brain included congestion and coagulative necrosis and in the stomach, congestion and haemorrhage. Easy availability of this cheap and highly toxic substance was responsible for the sudden spurt of poisoning with aluminium phosphide.

Adolescent↗
PubMed2004

Unusual presentation of lupus nephritis.

We report a male patient who presented with pyrexia, generalized lymphadenopathy, hepatosplenomegaly, and pleural effusion with no cutaneous or musculoskeletal symptoms. Despite extensive investigation, no cause was detected. His initial serology was also negative for autoantibodies. The patient was placed on a trial of antitubercular treatment in view of a positive Mantoux test. His disease evolved into the full clinical picture of systemic lupus erythematosus with nephritis (World Health Organisation class IV) and strongly positive antinuclear antibody and dsDNA over a period of months. He was treated successfully with intravenous cyclophosphamide pulses along with oral prednisolone, and the disease was still in remission after 3 years of follow-up.

Adult↗
PubMed2004

Multistrange baryon production in Au-Au collisions at sqrt[s(NN)]=130 GeV.

The transverse mass spectra and midrapidity yields for Xis and Omegas are presented. For the 10% most central collisions, the (-)Xi(+)/h(-) ratio increases from the Super Proton Synchrotron to the Relativistic Heavy Ion Collider energies while the Xi(-)/h(-) stays approximately constant. A hydrodynamically inspired model fit to the Xi spectra, which assumes a thermalized source, seems to indicate that these multistrange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to pi, K, p, and Lambdas.

Journal Article↗
PubMed2004

Cross sections and transverse single-spin asymmetries in forward neutral-pion production from proton collisions at sqrt[s]=200 GeV.

Measurements of the production of forward high-energy pi(0) mesons from transversely polarized proton collisions at sqrt[s]=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x(F) below about 0.3, and becomes positive and large at higher x(F), similar to the trend in data at sqrt[s]< or =20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p(T)>1 GeV/c at a polarized proton collider.

Journal Article↗
PubMed2004

Designing and executing scientific workflows with a programmable integrator.

MOTIVATION: As in many other fields of science, computational methods in molecular biology need to intersperse information access and algorithm execution in a computational workflow. Users often find difficulties when transferring data between data sources and applications. In most cases there is no standard solution for workflow design and execution and tailored scripting mechanisms are implemented in a case by case basis. RESULTS: In this paper, we present a general purpose 'programmable integrator' that can access information from a variety of sources in a coordinated manner. Its usefulness in complex bioinformatics applications is claimed and supported by some application examples. AVAILABILITY: Tools are freely available to non-profit educations and research institutions. Usage by commercial organizations requires a license agreement. Software requirements: Java v1.3 (http://java.sun.com), Xerces XML Parser (http://xml.apache.org/xerces-j) and Kweelt implementation of XQuery (http://kweelt.sourceforge.net/).

Algorithms↗
PubMed2004

Identified particle distributions in pp and Au+Au collisions at square root of (sNN)=200 GeV.

Transverse mass and rapidity distributions for charged pions, charged kaons, protons, and antiprotons are reported for square root of [sNN]=200 GeV pp and Au+Au collisions at Relativistic Heary Ion Collider (RHIC). Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

Journal Article↗
PubMed2004

Rho0 production and possible modification in Au+Au and p+p collisions at square root [sNN] = 200 GeV.

We report results on rho(770)(0)-->pi(+)pi(-) production at midrapidity in p+p and peripheral Au+Au collisions at sqrt[s(NN)]=200 GeV. This is the first direct measurement of rho(770)(0)-->pi(+)pi(-) in heavy-ion collisions. The measured rho(0) peak in the invariant mass distribution is shifted by approximately 40 MeV/c(2) in minimum bias p+p interactions and approximately 70 MeV/c(2) in peripheral Au+Au collisions. The rho(0) mass shift is dependent on transverse momentum and multiplicity. The modification of the rho(0) meson mass, width, and shape due to phase space and dynamical effects are discussed.

Journal Article↗
PubMed2004

Azimuthal anisotropy at the relativistic heavy ion collider: the first and fourth harmonics.

We report the first observations of the first harmonic (directed flow, v(1)) and the fourth harmonic (v(4)), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v(2)) generated at RHIC. From the correlation of v(2) with v(1) it is determined that v(2) is positive, or in-plane. The integrated v(4) is about a factor of 10 smaller than v(2). For the sixth (v(6)) and eighth (v(8)) harmonics upper limits on the magnitudes are reported.

Journal Article↗
PubMed2004

Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at square root of sNN=200 GeV.

We present STAR measurements of the azimuthal anisotropy parameter v(2) and the binary-collision scaled centrality ratio R(CP) for kaons and lambdas (Lambda+Lambda) at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV. In combination, the v(2) and R(CP) particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p(T) approximately 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K(0)(S) and Lambda+Lambda v(2) values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.

Journal Article↗
PubMed2004

A simple tendon retrieval method.

This report describes a simple technique of retrieving retracted proximal flexor tendon ends in Zone II injuries. This technique utilizes steel wires that are readily available in any hand set in the operating room. We have found that this is a consistently successful and atraumatic technique.

Bone Wires↗
PubMed2004

Selective use of mycophenolate mofetil in renal transplant patients in Indian scenario.

PURPOSE: Although mycophenolate mofetil (MMF) has emerged as a valuable immunosuppressive in renal transplantation, its high cost demands that it be used selectively. MATERIALS AND METHODS: This retrospectively study included 55 renal transplant patients on MMF for rescue therapy after treatment of acute vascular rejection (n = 45), acute/chronic liver disease with elevated transaminases (n = 4), early chronic rejection (n = 2), cyclosporine toxicity (n = 3), and cyclosporine-induced hemolytic-uremic syndrome (n = 1). The patients were given 1.5 to 2 g MMF in divided doses for at least 6 months, depending upon the tolerability, adverse effects, and finances, and followed for 1 year. The patients on MMF following treatment of acute rejections were compared with controls who received azathioprine-based triple immunosuppression after treatment of an acute rejection episode. RESULTS: The incidence of recurrent acute rejection in the first year was 18% in the MMF group compared to 42% in the control group (P < .005). The serum transaminases in the acute/chronic liver disease group reached normal levels at 3 to 6 months. The serum creatinine remained stable for a mean duration of 8 months in the early chronic rejection patients. The patients with cyclosporine toxicity showed stable graft function on low-dose cyclosporine. The patient with hemolytic-uremic syndrome showed stable graft function for 4 years. The MMF-based triple regimen is two times more expensive than an azathioprine-based regimen. CONCLUSION: MMF significantly decreases the recurrence of acute rejection. It is a good alternative agent in special situations like acute/chronic liver diseases with elevated transaminases, early chronic rejection, cyclosporine toxicity, and cyclosporine-induced hemolytic-uremic syndrome. Because of the high cost it should be used selectively in our population.

Acute Disease↗
PubMed2004

Fungal peritonitis in patients on continuous ambulatory peritoneal dialysis: a single centre Indian experience.

BACKGROUND: Fungal peritonitis (FP) is a serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD). We reviewed our FP cases to analyse the causative agents and possible risk factors in relation to FP and its outcome and mortality. METHODS: Records of all FP cases were reviewed. FP was diagnosed based on effluent cell count and positive fungal culture in suitable media. RESULTS: Between October 1993 and November 2001, 261 patients underwent CAPD. FP was detected in 28 patients, one episode in each patient (14.3% of the total peritonitis episodes). Candida species and dematiaceous fungi+/-Candida species were responsible for 89.3 and 10.7% of episodes, respectively. Patients with preceding bacterial peritonitis (BP) developed FP more frequently (25.6%) than de novo cases (2.9%) (P<0.0001) and lower proportion of them continued CAPD (8.6% vs. 60%; P=0.007). Mortality in patients having abdominal pain with and without fever, and catheter in situ was significantly higher than in those patients who did not have these risk factors (9/11 vs. 6/17, P=0.01; 13/17 vs. 2/11, P=0.003; 6/6, vs. 9/22, P=0.01, respectively). CONCLUSIONS: Higher proportion of our patients had FP; preceding BP was a significant risk factor for development of FP and technique failure. Abdominal pain+/-fever in patients and catheter in situ were identified as risk factors associated with mortality.

Female↗