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Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 307 records · Page 17Linked to original sources
PubMed2000

Molecular epidemiology of Entamoeba spp.: evidence of a bottleneck (Demographic sweep) and transcontinental spread of diploid parasites.

Entamoeba histolytica causes amebic colitis and liver abscess in developing countries such as Mexico and India. Entamoeba dispar is morphologically identical but is not associated with disease. Here we determined the ploidy of E. histolytica and developed PCR-based methods for distinguishing field isolates of E. histolytica or E. dispar. Fluorescence in situ hybridization showed that E. histolytica trophozoites are diploid for five "single-copy" probes tested. Intergenic sequences between superoxide dismutase and actin 3 genes of clinical isolates of E. histolytica from the New and Old Worlds were identical, as were those of E. dispar. These results suggest a bottleneck or demographic sweep in entamoebae which infect humans. In contrast, E. histolytica and E. dispar genes encoding repeat antigens on the surface of trophozoites (Ser-rich protein) or encysting parasites (chitinase) were highly polymorphic. chitinase alleles suggested that the early axenized strains of E. histolytica, HM-1 from Mexico City, Mexico, and NIH-200 from Calcutta, India, are still present and that similar E. dispar parasites can be identified in both the New and Old Worlds. Ser-rich protein alleles, which suggested the presence of the HM-1 strain in Mexico City, included some E. histolytica genes that predicted Ser-rich proteins with very few repeats. These results, which suggest diversifying selection at chitinase and Ser-rich protein loci, demonstrate the usefulness of these alleles for distinguishing clinical isolates of E. histolytica and E. dispar.

Actins↗
PubMed2000

Combination of didactic lecture with problem-based learning sessions in physiology teaching in a developing medical college in Nepal.

Physiology teaching as an essential part of medical education faces tremendous criticism regarding curriculum design, methods of implementation, and application of knowledge in clinical practice. In the traditional method of medical education, physiology is taught in the first year and involves little interdisciplinary interaction. The Manipal College of Medical Sciences, Pokhara, Nepal (affiliated with the Kathmandu Univ.) started in 1994 and adopted an integrated curriculum drawn along the lines of the student-centered, problem-based, integrated, community-based, elective-oriented, and systematic (SPICES) medical curriculum. Here, physiology is taught for the first 2 yr of the 4.5-yr Bachelor of Medicine, Bachelor of Surgery course. Methodology adopted is as follows. For a particular topic, objectives are clearly defined and priority content areas are identified. An overview is given in a didactic lecture class to the entire batch of 100 students. Tutorial classes are conducted thereafter with smaller groups of students (25/batch) divided further into five subgroups of five students each. In these sessions, a problem is presented to the students as a focus for learning or as an example of what has just been taught. Each problem was accompanied with relevant questions to streamline the students' thought processes. A tutor is present throughout the session not as an instructor but as a facilitator of the learning process. A questionnaire sought students' opinion on the usefulness of this approach, relevance of the combination of problem-based learning (PBL) sessions and didactic lectures in understanding a particular topic and relating clinical conditions to basic mechanisms, and improvement of performance on the university final examination. The majority of the students opined that the combination of didactic lectures and PBL sessions was definitely beneficial regarding all the above-mentioned aspects of learning. The university results corroborated their opinion. Thus it may be considered that a judicious mixture of didactic lectures and PBL sessions is beneficial as a teaching module of physiology in medical schools.

Clinical Competence↗
PubMed2000

Molecular mechanisms of NF-kappaB activation induced by bacterial lipopolysaccharide through Toll-like receptors.

Septic shock, caused by exaggerated host responses to various microbial products typified by lipopolysaccharide (LPS), remains the leading cause of death in trauma patients. Gaining insight into the nature of host interactions with LPS will certainly facilitate attempts to develop effective anti-sepsis drugs. Tremendous progress has been made during the past few years in understanding the mechanisms of pathogen-induced host responses. Toll-like receptor (TLR) 4 and 2 have been implicated as major receptors for signaling initiated by LPS and many other microbial products following their binding to CD14. In addition, many signaling intermediates involved in LPS-induced cell activation, particularly activation of the transcription factor NF-kappaB, have been identified and characterized. Further investigations with these molecules will certainly reward us with more effective therapeutic drugs to treat septic shock as well as many other inflammatory and infectious disorders.

Animals↗
PubMed2000

Treatment of central nervous system infections: a neurosurgical perspective.

Almost any microorganism has the potential to infect the human central nervous system. Neurosurgical intervention may be required for tissue assay, to establish a microbiologic diagnosis, for decompression of space-occupying lesions with significant mass effects, or for definitive treatments such as cerebrospinal fluid diversion. This article surveys the surgical management of intracranial infections with special emphasis on subdural and epidural empyema, brain abscesses, mycotic aneurysms, and neurocysticercosis.

Brain Diseases↗
PubMed2000

Respiratory syncytial virus infections in immunocompromised adults.

The past decade has witnessed a growing appreciation of the existence, frequency, and potential lethality of community respiratory virus infections such as RSV in some subsets of immunocompromised adults. The enigmatic "idiopathic pneumonia" and "pneumonia of unknown origin" have become more fathomable. As a result, a simple upper respiratory illness in a high-risk immunocompromised adult is no longer viewed as trivial. The paramount importance of simple hygienic practices has been underscored, and contamination of high-risk immunocompromised patients with respiratory secretions is now discouraged with the same rigor as contamination with urine, feces, or blood. Likewise, the risks and benefits of administering intensive chemotherapy in the setting of a seemingly benign upper respiratory illness are now weighed heavily. The diagnosis is suspected and pursued, and the available therapies are administered promptly. Widespread efforts are now under way to elucidate the pathogenesis of these viral pneumonias and to identify the immunodeficiencies predisposing patients to serious disease. In addition, efforts are being made to develop effective diagnostic, prophylactic, and therapeutic strategies. The growing need for more effective, easier-to-administer, less costly antiviral therapy is apparent.

AIDS-Related Opportunistic Infections↗
PubMed2000

Stromal sarcoma of breast: a case report.

A 34 years unmarried female was admitted with an ulcerated foul smelling growth in her right breast. On examination the fungating mass measured 17.5 cm x 15 cm in central and lower part of right breast involving the nipple and areola. The ulcer was covered with slough and rest part of the breast appeared bosselated. Her Hb was 4 g/dl and incision biopsy from the margin of the tumour showed histology of sarcoma. The patient was infused 6 units of blood and right sided total mastectomy was done. Histopathological examination confirmed it was a case of stromal sarcoma of breast. Chemotherapy was started with vincristine, adriamycin and cylophosphamide. The patient was doing well in next follow-up.

Adult↗
PubMed2000

Characterization of an in vitro model for the study of the short and prolonged effects of myocardial ischaemia and reperfusion in man.

The mechanisms underlying myocardial ischaemia and reperfusion-induced injury have been investigated, mainly by using animal experimental preparations in vitro and in vivo, but little is known of the process in human myocardium. The present studies characterize an in vitro model using human myocardium for the study of early and delayed effects of ischaemia and reperfusion. The right atrial appendage was manually sliced and incubated in buffer through which was bubbled O(2)/CO(2) (19:1, v/v) for various time periods. Lactate dehydrogenase (LDH) leakage, 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl-2H-tetrazolium bromide (MTT) reduction, oxygen consumption, nucleotide levels and tissue morphology were all investigated as markers of myocardial injury. The specimens remained stable and viable up to 24 h, but had significantly deteriorated by 48 h. The preparation responded to ischaemia in a time-related manner. Tissue viability was reduced by 25% after 30 min ischaemia, declined to 60% after 60 min ischaemia and to 75% after 120 min ischaemia. Interestingly, the tissue was more susceptible when ischaemia was induced after 24 h of aerobic incubation. The effects of the duration of reperfusion were investigated after a fixed 60 min ischaemic insult. The results of LDH leakage suggest that reperfusion injury is mainly sustained within the first 2 h of reperfusion. However, the results of MTT reduction show that there is a progressive decrease in tissue viability over the 24 h reperfusion period, possibly reflecting the occurrence of tissue necrosis and apoptosis at different reperfusion times. In conclusion, the data provide evidence that the incubation of human atrial tissue in vitro is stable, and slices are viable for at least 24 h, which permits the study of early and delayed consequences of ischaemia and reperfusion in the human myocardium.

Buffers↗
PubMed2000

Outbreak of cholera caused by Vibrio cholerae 01 intermediately resistant to norfloxacin at Malda, West Bengal.

During the end of September 1997, an unusual outbreak of severe dehydrating watery diarrhoea cases and deaths were reported from Malda town. Vibrio cholerae 01 El tor, the causative agent responsible for this episode was isolated from 56.5% of cases sampled. Three of the five drinking water samples were also positive for V cholerae 01. Majority of cases were adults. Isolated strains were uniformly resistant to furazolidone and intermediately to norfloxacin. Indiscriminate use of antibiotic should be discouraged for development of multidrug resistant strains.

Adult↗
PubMed2000

The newer unconventional indications of permanent pacemakers.

In recent years, the indications for permanent pacemakers have expanded. The interest has focussed on hypertrophic cardiomyopathy, dilated cardiomyopathy and a new entity called hypertensive hypertrophy with cavity obliteration (HHCO). Pacemaker therapy is establishing itself for the prevention of atrial fibrillation. Pacing for neurocardiogenic syncope with newer pacing mode has encouraging datas. Pacemaker for long QT syndrome, after cardiac transplant and for haemodynamic improvement in occasional cases of first degree atrio-ventricular block is getting attention. The AHA and ACC guidelines updated in 1998 for implantation of cardiac pacemakers, now include several of these newer indications.

Atrial Fibrillation↗
PubMed2000

Pilot-scale gasification of municipal solid wastes by high-rate and two-phase anaerobic digestion (TPAD).

Bioconversion of municipal solid waste-sludge blend by conventional high-rate and two-phase anaerobic digestion was studied. RDF (refused-derived fuel)-quality feed produced in a Madison, Wisconsin, USA, MRF (materials-recovery facility) was used. High-rate digestion experiments were conducted with bench-scale digesters under target operating conditions developed from an economic feasibility study. The effects of digestion temperature, RDF content of digester feed, HRT, loading rate, RDF particle size, and RDF pretreatment with cellulase or dilute solutions of NaOH or lime on digester performance were studied. A pilot-scale two-phase digestion plant was operated with 80:20 (weight ratio) RDF-sludge blends to show that this process exhibited a higher methane yield, and produced a higher methane-content digester gas than those obtained by single-stage, high-rate anaerobic digestion.

Bacteria, Anaerobic↗
PubMed2000

Kinetics of accelerated solid-state fermentation of organic-rich municipal solid waste.

Biotransformation of landfill solid wastes is a slow process requiring decades for completion. Accelerated anaerobic fermentation in modulated landfill environments may alleviate or eliminate pollution of land, water and air. This research was undertaken to demonstrate the application of biphasic fermentation to a simulated laboratory-scale landfill to effect rapid biomethanation of biodegradable solids. The biphasic process consisted of solid-state, acidogenic fermentation of the organic fraction of MSW followed by biomethanation of acidic hydrolysates in a separate methane fermenter. Solid-state fermentation of the MSW with effluent recirculation resulted in rapid hydrolysis, acidification and denitrification, with soluble COD and VFA concentrations accumulating to inhibitory levels of 60,000 mg/l and 13,000 mg/l, respectively, at a pH of 4.5. The landfill gas methane concentration reached a maximum of 55 mol.%. By comparison, the methanogenic reactor produced high methane-content (70-85 mol.%) gases. The biphasic process effected carbohydrate, lipid, and protein conversion efficiencies of 90%, 49%, and 37%, respectively. Development of a Monod-type product-formation model was undertaken to predict methane formation and to determine kinetic parameters for the methanogenic processes in the simulated landfill and separate methane reactors. A first-order solids hydrolysis rate constant of 0.017 day-1 was evaluated to show that landfill solids hydrolysis was slower than the inhibited methanogenesis rate.

Bacteria, Anaerobic↗