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Biomedical subjects

S Das

Publications and source records attributed to S Das.

At least 91 records · Page 5Linked to original sources

Unicompartmental knee arthroplasty. 2- to 12-year results in a community hospital.

We report the outcome of 135 knees with anteromedial osteoarthritis in which the Oxford meniscal-bearing unicompartmental arthroplasty was inserted in a district general hospital by a single surgeon. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and the lateral compartment was uninvolved or had only minor osteoarthritis. The mean follow-up was 5.82 years (2 to 12). Using revision as the end-point, the outcome for every knee was established. Five knees have been revised giving a cumulative rate of survival of the prosthesis at ten years of 94.04% (95% confidence interval 84.0 to 97.8). Knee rating and patient function were assessed using the modified Knee Society scoring system. The mean knee score was 92.2 (51 to 100) and the mean functional score 76.2 (51 to 100). The survival of the implant is comparable to that reported by the designers of the prosthesis and not significantly different from that for total knee replacement. Unicompartmental knee replacement offers a viable alternative in patients with medial osteoarthritis. Appropriate selection of patients and good surgical technique are the key factors.

Aged↗

Life-threatening necrotizing fasciitis of the neck: an unusual consequence of a sore throat.

BACKGROUND: Necrotizing fasciitis is life-threatening bacterial infection which spreads with frightening speed along the fascial planes resulting in extensive tissue necrosis and often death. The infection is caused by either Group A streptococci or a combination of aerobic and anaerobic bacteria. Necrotizing fasciitis of the neck is rare and commonly has a dental origin. CASE REPORT: Here we present a unique case of the condition that was preceded by a sore throat in a young immunocompetent woman. We also describe, for the first time, a successful outcome involving primary skin closure and daily irrigation of the wound with hydrogen peroxide.

Adult↗

Simultaneous infection with multiple strains of Mycobacterium tuberculosis identified by restriction fragment length polymorphism analysis.

Simultaneous infection with multiple strains of Mycobacterium tuberculosis was confirmed in two isolates of a total of 543 culture-positive tuberculosis patients from the Model DOTS area of Thiruvallur, South India, using IS6110 and direct repeat restriction fragment length polymorphism (DR-RFLP). The two isolates showing different intensities of IS6110 band patterns were further analysed by repeating RFLP on their alternate cultures and individual colonies. The results showed respectively two and three distinct IS6110 RFLP patterns, indicating mixed infection. The possibility of cross contamination at laboratory or DNA level was ruled out. Additional DR-RFLP also confirmed infection with multiple strains. This study found evidence of co-infection with two or three different strains of M. tuberculosis, showing distinct RFLP patterns.

Adult↗

Comparative evaluation of cancer chemopreventive efficacy of alpha-tocopherol and quercetin in a murine model.

Chemopreventive efficacy and the mode of action of alpha-tocopherol and quercetin, both known to possess anti-oxidant properties, were evaluated during carcinogenesis in uterine cervix of mice by chronic exposure to methylcholanthrene. Oral administration of alpha-tocopherol and quercetin could reduce the genotoxic effect of the carcinogen as revealed by the micronucleus frequency in vaginal epithelial cells. Both could restrict the progression of dysplastic changes in cervix uteri leading to carcinoma in-situ but the influence of the quercetin was more pronounced. A decrease in lipid peroxides following ingestion of these agents suggests that their chemopreventive action is due to their protective role on DNA damage by free radicals. Increased glutathione and glutathione-s-transferase also indicate their involvement in detoxification. While alpha-tocopherol activated the PBL response towards mitogenic stimulation, quercetin had no such effect.

Animals↗

Repeated dose toxicity of alfa-cypermethrin in rats.

The present study was performed to investigate the subacute effect of alpha-cypermethrin (alpha-CP) in rats. Alfacypermethrin a synthetic pyrethroid insecticide, dissolved in dimethyl sulfoxide (DMSO) and oral LD50 was investigated after administering orally different doses in rats and was determined as 145 mg/kg. Other groups of rats were given repeated daily oral dose (1/10 LD50) of alpha-CP for 30 days. The animals were sacrificed on 31st day. Activities of various enzymes, cytochrome P450 and b5 contents in liver, hepatic antioxidant status, tissue residue concentration, haemogram and pathological changes were studied. It increased the serum aminotransaminases (AST, ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) activities and blood glucose level significantly. alpha-CP decreased RBC count, PCV and Hb level significantly. It significantly decreased cytochrome P450 in liver. Residues were present in different tissues. It increased malondialdehyde (MDA) level, while decreased the activities of catalase (CAT), superoxide dismutase (SOD) and glycogen level in liver significantly. Mild to moderate histological alterations were observed in lungs, liver, stomach, kidneys, testes and cerebellum. So repeated daily oral doses of alpha-CP at 1/10LD50 altered the biochemical parameters, decreased cytochrome P450 content, antioxidant status, which correlated with histopathological changes of tissues.

Alanine Transaminase↗

Pion-Kaon correlations in central Au+Au collisions at square root [sNN] = 130 GeV.

Pion-kaon correlation functions are constructed from central Au+Au STAR data taken at sqrt[s(NN)]=130 GeV by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e., transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion.

Journal Article↗

Mosaic mutations of the LIS1 gene cause subcortical band heterotopia.

BACKGROUND: Subcortical band heterotopia (SBH) is a neuronal migration disorder. DCX mutations are responsible for almost all familial cases, 80% of sporadic female cases, and 25% of sporadic male cases of SBH, and are associated with more severe gyral and migration abnormality over the anterior brain regions. Somatic mosaicism has previously been hypothesized in a patient with posteriorly predominant SBH and a mutation of the LIS1 gene, which is usually mutated in patients with severe lissencephaly. The authors identified mosaic mutations of LIS1 in two patients (Patients 1 and 2) with predominantly posterior SBH. METHODS: After ruling out DCX mutations, the authors performed sequencing of the LIS1 gene in lymphocyte DNA. Because sequence peaks in both patients were suggestive of mosaic mutations, they followed up with denaturing high-pressure liquid chromatography analysis on blood and hair root DNA and compared the areas of heteroduplex and homoduplex peaks. A third patient showing the same mutation as Patient 2 but with no evidence of mosaicism was used for comparing the phenotype of mosaic vs full mutation. RESULTS: The two patients with posterior SBH harbored a missense (Arg241Pro) and a nonsense (R8X) mosaic mutation of LIS1. The rate of mosaicism in Patient 1 was 18% in the blood and 21% in the hair roots, whereas in Patient 2 it was 24% and 31% in the same tissues. The patient with a full R8X mutation of LIS1 had severe lissencephaly. CONCLUSIONS: Subcortical band heterotopia can occur with mosaic mutations of the LIS1 gene. Mutation analysis of LIS1, using highly sensitive techniques such as denaturing high-pressure liquid chromatography, should be considered for patients with posteriorly predominant subcortical band heterotopia and pachygyria.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5<p(T)<12 GeV/c. The collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

Journal Article↗

Molecular characterization of a human rotavirus reveals porcine characteristics in most of the genes including VP6 and NSP4.

Long electropherotype with Subgroup I specificity is a common feature of animal rotaviruses. In an epidemic of infantile gastroenteritis in Manipur, India, long but SG I strains predominated in the outbreak in the year 1987-88. One such strain isolated from that region, following the outbreak had G9P [19] specificity. As this is a rare combination, the gene sequences encoding VP4, VP6, VP7, NSP1, NSP2, NSP3, NSP4 and NSP5 of this strain were analyzed. All these genes except VP7 were closely related to porcine rotaviruses (95-99% identity at amino acid level) and clustered with the porcine strains in phylogenetic analysis. In addition, it had subgroup I nature and belonged to NSP4 genotype B which is characteristic of animal rotaviruses. This is the first report of a rotavirus with VP6 and NSP4, two crucial proteins thought to be involved in host range restriction and pathogenicity, were of porcine origin and caused diarrhoea in a human host. Among the genes of this strain sequenced so far, only VP7 had highest identity to human strains at amino acid level. This study suggests reassortment may be occurring between human and other animal strains and some of the reassortant viruses may be virulent to humans.

Animals↗

Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC.

We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.

Journal Article↗

Swelling behaviour of poly(methylmethacrylate) thick resist layers in deep X-ray lithography.

The understanding and optimization of lithographic conditions are particularly important for irradiation of thick resist layers in deep X-ray lithography. The causes and consequences of radiation-induced formation and accumulation of gaseous species inside the poly(methylmethacrylate) (PMMA) resist matrix are discussed. Thick PMMA layers were exposed to high-energy photons from a bending-magnet beamline at the Center for Advanced Microstructures and Devices (CAMD). The focus of this work was to explore the swelling behaviour of PMMA resist of thickness between 50 micro m and 1.6 mm. The influence of various exposure parameters, such as photon energy, filtering conditions, electron current in the storage ring, scan length and scan speed, exposure atmosphere etc., on the swelling of the resist are discussed. The effect of pre-exposure annealing of the PMMA sheets and of temperature variation during irradiation was also investigated. Exposure with optimized X-ray spectral distribution, incident power density, absorbed dose and rate of energy deposition inside the resist allowed swelling of the resist to be minimized during exposure.

Journal Article↗

Changing trends in bacteriology of burns in the burns unit, Delhi, India.

A retrospective study of bacterial isolates from the wounds of patients admitted to burns unit, was undertaken at Guru Tegh Bahadur Hospital, University College of Medical Sciences, Delhi, India, over a period of 5 years between July 1997 and April 2002. The study compared the results obtained with the previous 5 years data (June 1993-June 1997) from the same unit to determine the changing patterns and emerging trends of bacterial isolates and their antimicrobial susceptibilities. Pseudomonas species (31%) and Staphylococcus aureus (22%) were the most common pathogens followed by Klebsiella species (19%). Multi-drug resistant (MDR) Acinetobacter species (9%) have emerged as an important nosocomial pathogen in our burn unit. Most of the gram-negative isolates obtained were found to be multi-drug resistant and 61% of the tested isolates were extended spectrum beta-lactamase (ESBL) producers. Concomitant resistance to penicillin and aminoglycosides was observed in 61% of Enterococcus fecalis isolates. When compared with the results of previous 5 years (June 1993-June 1997) Pseudomonas spp. was still the commonest pathogen in the burns unit. However, isolation of this organism and other gram-negative organisms has decreased in comparison to previous years. The incidence of antimicrobial resistance has markedly increased over the past years resulting in limitation of therapeutic options.

Burn Units↗

Hand-assisted laparoscopic vs the open (flank incision) approach to radical nephrectomy.

OBJECTIVE: To compare the outcome in contemporaneous groups of patients undergoing hand-assisted laparoscopic radical nephrectomy (HALRN) or open (flank) radical nephrectomy (ORN), as many series worldwide have confirmed the feasibility and advantages of LRN in managing renal cell carcinoma (RCC). PATIENTS AND METHODS: We retrospectively evaluated 44 patients who underwent radical nephrectomy for RCC from 1999 to 2001, 22 by HALRN and 22 by ORN, through an extraperitoneal 11th or 12th rib flank incision. Standard perioperative variables were assessed; a validated questionnaire was also sent to each patient after surgery, allowing them to report their overall satisfaction and the period needed for them to return to both routine and full activities. The outcomes of HALRN and ORN were compared using Wilcoxon rank-sum analysis. RESULTS: There was a statistically significant difference between HALRN and ORN in operative duration, length of hospital stay, total narcotic requirement, pain scores at 1 week and 1 month after surgery, and the time to resume routine and full activity, with all variables (except operative duration) lower in the HALRN group. There were no significant differences between the groups in pain at 1-3 days, estimated blood loss or overall satisfaction. CONCLUSION: Compared with ORN, HALRN is associated with lower narcotic requirement, pain scores, a shorter hospital stay and earlier resumption of routine and full activities. However, several obstacles remain, including increased operative duration and the increased equipment costs.

Age Factors↗

Tomato and garlic can modulate azoxymethane-induced colon carcinogenesis in rats.

Tomato (Lycopersicon esculentum) and garlic (Allium cepa) are important constituents of the human diet. Compounds like diallyl sulfides, diallyl disulfides and quercetin, which are active components of garlic, have known anti-inflammatory, antimutagenic activities. Similarly, active components in tomato, such as kaempferol and chlorogenic acid, have antimutagenic activities and lycopene is the most active oxygen quencher with potential chemopreventive activities. In view of this, an endeavour was made to evaluate the anticarcinogenic effect, if any, of tomato and garlic consumption individually and in combination on azoxymethane-induced colonic precancerous lesion, the aberrant crypt foci in animal model. Sprague-Dawley rats (4-5 weeks old) were injected with azoxymethane (15 mg/kg b.w.) and orally administered with 2% (w/v) of tomato, garlic and a combination of both. After 12 weeks of first azoxymethane injection, colons were assessed for aberrant crypt foci and compared with the carcinogen control group. Lipid peroxidation level and glutathione-S-transferase (GST) activity were assessed in liver as well as in colon. Furthermore, in situ cell proliferation and apoptosis were estimated using the Brdu incorporation method and TUNEL method respectively. It was observed that aberrant crypt foci were reduced in all treated groups (by 32.11% in garlic, by 76.14% in tomato and by 55.96% in the combination group). Among treated groups, GST activity was found to be induced in both liver and colon, whereas considerable reduction in lipid peroxidation level was observed in liver as well as in colon with respect to the carcinogen control group. Significant reduction in Brdu labelling index and increase in apoptotic index in colon was noted in the treated groups. These results suggest that tomato and garlic suspensions have a protective effect on colon carcinogenesis, which is mediated by modulation of different biological pathways during carcinogenesis.

Animals↗

Apophysomyces elegans: an emerging zygomycete in India.

Apophysomyces elegans was considered a rare but medically important zygomycete. We analyzed the clinical records of eight patients from a single center in whom zygomycosis due to A. elegans was diagnosed over a span of 25 months. We also attempted a DNA-based method for rapid identification of the fungi and looked for interstrain polymorphism using microsattelite primers. Three patients had cutaneous and subcutaneous infections, three had isolated renal involvement, one had rhino-orbital tissue infection, and the final patient had a disseminated infection involving the spleen and kidney. Underlying illnesses were found in two patients, one with diabetes mellitus and the other with chronic alcoholism. A history of traumatic implantation was available for three patients. All except two of the patients responded to surgical and/or medical therapy; the diagnosis for the two exceptions was made at the terminal stage of infection. Restriction enzyme (MboI, MspI, HinfI) digestion of the PCR-amplified internal transcribed spacer region helped with the rapid and specific identification of A. elegans. The strains could be divided into two groups according to their patterns, with clustering into one pattern obtained by using microsatellite [(GTG)(5) and (GAC)(5)] PCR fingerprinting. The study highlights the epidemiology, clinical spectrum, and diagnosis of emerging A. elegans infections.

Adult↗