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Biomedical subjects

S Sengupta

Publications and source records attributed to S Sengupta.

At least 91 records · Page 5Linked to original sources
PubMed2000

Multistage electrophoresis system for the separation of cells, particles and solutes.

It is common to operate equilibrium-based separation methods, such as distillation and extraction, as multistage unit operations, in which equilibrium is presumably achieved within each stage. Two rate-based separation processes, free electrophoresis and magnetic particle separation, have now been operated in multistage mode. Preparative free electrophoresis of particles and solutes has resisted scale-up and is confined to a narrow range of ionic compositions. Natural convection induced in electrophoresis buffers by Ohmic heating has been a strong deterrent and has led to such measures as radial electrophoresis in Couette flow, free-flow electrophoresis, low-gravity electrophoresis, density gradient electrophoresis, and reorienting density gradient electrophoresis, to name a few. The short vertical electrophoresis path exploited in the last-mentioned forms the basis for multistage electrophoresis. A thin-layer countercurrent distribution apparatus was designed and constructed so that up to 20 fractions could be collected on the basis of electrophoretic mobility by applying an electric field. The mixture to be separated starts in a bottom cavity, and successive top cavities collect fractions as separand particles or molecules are electrophoresed upward out of the bottom cavity. Mathematical models of this process were developed, and experiments were performed to verify the predictions of the models by collecting and counting particles in each cavity after fractionation.

Animals↗
PubMed2000

Etoposide encapsulated in positively charged liposomes: pharmacokinetic studies in mice and formulation stability studies.

Etoposide is an antineoplastic agent which acts by forming a ternary complex with topoisomerase II and DNA, causing DNA breaks and cell death. In recent studies we have demonstrated that encapsulation in liposomes increases the antitumour efficacy and reduces the adverse effects associated with etoposide. The present study was thus conducted to evaluate whether encapsulation in cationic liposomes altered the pharmacokinetics of etoposide and to study the effect of cholesterol incorporation on the stability of the liposomes. Etoposide-encapsulated unilammellar liposomes were synthesized by thin film hydration followed by extrusion. The drug was administered to Swiss albino mice at a dose of 10 mg kg(-1). The concentration of the drug in plasma was analysed at different time points till 360 min after injection, using a h.p.l.c. method. The terbium chloride-dipicolinic acid interaction method was applied to study the stability of the formulation in mouse serum and also following storage at 0( composite function)C over a period of time. The effect of the free and liposomal drug on myelosuppression was evaluated at 10 mg m(-2)and 40 mg m(-2)dose levels by quantifying blood cell counts on day 15 and day 21 following a 5 day course of therapy. Encapsulation in cationic liposomes increased the area under the concentration vs time curve to 42.98 microghml(-1)from 24.18 microghml(-1)in the case of the free drug. Half-life (beta) was 58. 62 and 186 min in the case of free and liposomal etoposide, respectively. In the stability studies, incorporation of cholesterol progressively stabilized the formulation in serum. The use of sucrose at increasing concentrations as a cryoprotectant also increased the shelf stability of the formulation at 0( composite function)C. Toxicity studies using a dose of pure drug revealed that though myelosuppression was evident in both liposomal- and free drug-treated groups on day 15 it was reversed by day 21 following initiation of therapy. The present findings suggest that liposomes could serve as an alternative mode of delivery for etoposide.

Analysis of Variance↗
PubMed2000

Stethoscopes and nosocomial infection.

Stethoscopes are an essential tool of the medical profession and can become a source of nosocomial infection. A study conducted in the Department of Pediatrics, Kasturba Medical College and Hospital showed a high carriage of methicillin resistant staphylococcus (69.76%) and multi-drug resistant Gram negative bacilli (20.93%) on regularly used stethoscopes. The antibiogram of the bacterial isolates strongly suggested these to be nosocomial strains. A verbal survey revealed that regular cleaning is not common among doctors. A policy regarding cleaning of stethoscopes with an effective disinfectant may be helpful in reducing hospital-associated infections.

Child↗
PubMed2000

A note on the estimation of microbial glycosidase activities by dinitrosalicylic acid reagent.

In the estimation of glycosidase activity by dinitrosalicylic acid (DNS) reagent, the stoichiometry of DNS reduction was reported to increase proportionately with the increase in the number of glycosidic linkages present in oligosaccharides liberated by the enzyme. The relationship between increases in DNS reduction and increases in the number of glycosidic bonds was found to be represented by a part of a rectangular hyperbola. The increase was optimum with disaccharide and insignificant when the degree of polymerization (DP) was > or =10. The difference did not arise as a result of the DNSA discriminating between mono- and oligosaccharide oxidation. The relationship stemmed from the acidity of the hydroxyl group adjacent to the reducing group, which repressed DNS reduction. The acidity is likely to decrease with an increase in oligosaccharide chain length. It is suggested that DNS reduction is actually optimum and uniform for all oligosaccharides of DP > or = 10 and that it is minimum for monosaccharide. Thus the introduction of rectification factors in the estimation of glycosidase activities by the DNS method appears to be justified.

Agaricales↗
PubMed2000

Accumulation of a natural substrate of laccase in gills of Pleurotus florida during sporulation.

During sporulation, laccase activity of Pleurotus florida decreased to a minimum level in spite of increase in the number of isozymes. An endogenous laccase substrate was detected especially in the gill structure of the sporophore, which competitively inhibited oxidation of guaiacol by the enzyme during in vitro assay. Appearance of the laccase substrate in the gill structure may be linked with the sporulation phenomenon.

Guaiacol↗
PubMed2000

Case-control and qualitative study of attrition in a community epilepsy programme in rural India.

Dropout from epilepsy programmes is a serious problem in developing countries and has not been systematically studied before. We set up a community-based programme for children with epilepsy in rural India. The aim of this study was to assess reasons for dropout. We assessed medical and sociodemographic variables for their effect on dropout at 12 months using an unmatched case-control design on 32 cases and 62 controls. We also interviewed the parents of 32 children who dropped out of treatment, using a topic schedule. Two-thirds of the dropouts occurred within the first 6 months of treatment. Severely impaired children were more likely to drop out (odds ratio 4.60, 95% CI: 1.0-21.0) and families who had tried AEDs before were less likely to do so (odds ratio 0.12, 95% CI: 0.015-0.88). Denial of diagnosis, access problems and symptom resolution were the other main reasons underlying attrition. Active ascertainment methods should be reconsidered in community programmes. Very poor families without a male head or with long journey times are at high risk of dropout. People with severe impairments need appropriate integrated rehabilitation.

Adolescent↗
PubMed2000

CT analysis of caliceal anatomy in the supine and prone positions.

PURPOSE: To assess the effect of patient positioning on the position of the kidneys and their consequent projection onto plain radiographs, thus ascertaining the need for special preoperative imaging. PATIENTS AND METHODS: Fourteen patients were studied by obtaining fine (5-mm)-cut contrast-enhanced CT scans in the pyelogram phase in both the supine and prone position. The orientation of the kidneys relative to the midsagittal plane of the body and the orientation of the anterior and posterior calices relative to the axis of the kidney were measured from hardcopy images. Comparison was made between prone and supine positions for left and right kidneys separately, as well as overall. RESULTS: The position of the patient had a small effect on the orientation of the kidneys, with the mean angle changing from 56.6 degrees when supine to 61.6 degrees when prone (p < 0.05). However, no significant change in caliceal orientation or the relative projection of the anterior and posterior calices occurred as a result. CONCLUSION: There is no need to carry out special preoperative imaging in the operative or prone position.

Adult↗
PubMed2000

Environmental dosimetry performance criteria: pilot test of proposed ANSI draft standard N13.29. American National Standards Institute.

American National Standards Institute (ANSI) standards are a source of technical guidance on the application of passive radiation detectors in personnel and environmental monitoring programs. The proposed new ANSI Draft N13.29 describes performance tests for environmental dosimetry providers that are analogous to those now required in personnel dosimetry. The objective of this study was to pilot test the procedural specifications before Draft N13.29 is submitted for final balloting. The results of the performance tests are relevant to environmental surveillance programs, which may be affected if Draft N13.29 is approved. Seven environmental dosimetry providers submitted dosimeters for the pilot test, which included two phases. The first phase involved exposing dosimeters to laboratory gamma, beta, and x-ray sources at routine and accident dose levels. In the second phase, dosimeters were subjected to 90 d of simulated environmental conditions in a chamber that cycled through prescribed temperature and humidity parameters and lighting conditions. Two participants passed all categories of the laboratory test phase, and all seven passed the environmental test phase. We report here on the results of the performance tests; additional results relevant to finalizing Draft N13.29 are detailed elsewhere.

Environmental Monitoring↗
PubMed2000

Elastic constants from microscopic strain fluctuations

Fluctuations of the instantaneous local Lagrangian strain epsilon(ij)(r,t), measured with respect to a static "reference" lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse-grained by averaging them within subsystems (of size L(b)) of a system (of total size L) in the canonical ensemble. Using a simple finite size scaling theory we predict the behavior of the fluctuations as a function of L(b)/L and extract elastic constants of the system in the thermodynamic limit at nonzero temperature. Our method is simple to implement, efficient, and general enough to be able to handle a wide class of model systems, including those with singular potentials without any essential modification. We illustrate the technique by computing isothermal elastic constants of "hard" and "soft" disk triangular solids in two dimensions from Monte Carlo and molecular dynamics simulations. We compare our results with those from earlier simulations and theory.

Journal Article↗
PubMed2000

Elastic moduli, dislocation core energy, and melting of hard disks in two dimensions

Elastic moduli and dislocation core energy of the triangular solid of hard disks of diameter sigma are obtained in the limit of vanishing dislocation-antidislocation pair density, from Monte Carlo simulations that incorporate a constraint, namely that all moves altering the local connectivity away from that of the ideal triangular lattice are rejected. In this limit we show that the solid is stable against all other fluctuations at least up to densities as low as rhosigma(2)=0.88. Our system does not show any phase transition so diverging correlation lengths leading to finite size effects and slow relaxations do not exist. The dislocation pair formation probability is estimated from the fraction of moves rejected due to the constraint which yields, in turn, the core energy E(c) and the (bare) dislocation fugacity y. Using these quantities, we check the relative validity of first order and Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) melting scenarios and obtain numerical estimates of the typical expected transition densities and pressures. We conclude that a KTHNY transition from the solid to a hexatic phase preempts the solid to liquid first order transition in this system albeit by a very small margin, easily masked by crossover effects in unconstrained "brute- force" simulations with a small number of particles.

Journal Article↗
PubMed2000

Effect of retinoic acid on integrin receptors of B16F10 melanoma cells.

The intriguing problem of metastasis requires the spreading of metastatic cells through the basement membrane barrier. The interaction of the basement membrane with the metastatic cell is a cell surface activity involving the function of integrin receptors. Integrins are a group of alpha,beta heterodimeric proteins responsible for transducing intracellular signals on binding to the extracellular matrix proteins present in the basement membrane. To understand the role of integrin receptors in tumor metastasis, the cell surface receptor functions were modulated by All Trans Retinoic Acid (ATRA) treatment in B16F10 tumor cells. Our experimental results clearly indicate that All Trans Retinoic Acid (ATRA) inhibit metastatic potential of highly metastatic B16F10 melanoma cells by 1) downregulating the cell surface integrin receptors against ECM proteins specially laminin and vitronectin and 2) by inhibiting the 72 kd collagenase activity.

Antineoplastic Agents↗
PubMed2000

Evaluation of safety and efficacy of supirocin-B (mupirocin 2% + betamethasone dipropionate 0.05%) in infected dermatoses--a post marketing study.

The aim of the present post marketing study was to study the safety and efficacy of supirocin-B ointment (mupirocin 2% + betamethasone dipropionate 0.05%) in the treatment of infected dermatoses. For this purpose physicians from different parts of India were requested to keep the clinical records prospectively as per a specially designed proforma over a follow-up period of 7 days, whenever they prescribed supirocin-B ointment (mupirocin 2% + betamethasone dipropionate 0.05%) for local application, three times a day, to their patients having either primary infection complicated by dermatoses or dermatoses infected secondarily. From the analysis of 251 clinical records contributed by 27 physicians, it was evident that in clinical practice, supirocin-B ointment (mupirocin 2% + betamethasone dipropionate 0.05%) was found to be safe and very effective by physicians in the treatment of infected dermatoses in 94.8% of the patients. Similarly 92.4% of the patients reported more than 70% improvement in their symptoms after 7 days of treatment. No adverse effects were reported during the treatment period by any of the patients except worsening of skin lesions by one patient. Thus from this study, supirocin-B ointment (mupirocin 2% + betamethasone dipropionate 0.05%) seems to be safe and effective in the treatment of infected dermatoses.

Betamethasone↗
PubMed2000

Spectrum of antibiogram against pathogens related to respiratory tract infections with a special reference to ceftibuten: a multicentric study.

In a multicentric study at several leading hospitals of this country, microbiological assessment was carried out in 500 specimens from patients suffering from respiratory tract infections (RTIs; both upper and lower) for a period of 6 months from January, 1999 to June, 1999. The antibiotic sensitivity study was done in 201 isolates from 500 different specimens of throat swab, postpharyngeal swab, sinusitis drainage fluid, sputum, broncho-alveolar lavage (BL), etc. Ceftibuten, an orally active third generation cephalosporin showed encouraging results when compared with seven other selected antibiotics used for RTI. The majority of the patients with acute or chronic RTIs showed an excellent in vitro response to ceftibuten in the analysis of the isolates. Seventy to ninety per cent of the isolated respiratory pathogens were found to be sensitive to ceftibuten in vitro; which offers a promising alternative to other antibiotics included in this study.

Administration, Oral↗
PubMed2000

An evaluation of patient access to their electronic medical records via the World Wide Web.

This paper describes initial experience with the Web-based Patient Clinical Information System (PatCIS). The system was designed to serve as a framework for the integration of applications that help patients access their electronic medical record, add data to their record, review on-line health information, and apply their own clinical data (automatically) to guideline programs that offer health advice. The architecture supports security functions and records user activities, relieving application developers from concerns about safe information practices and the evaluation process. PatCIS is being used to study the social and cognitive impact of allowing patients to have access to their health records via the Web. To date, PatCIS has grown to include 15 clinical functions and 4 dynamic links to literature (called infobuttons). Eleven patients have been enrolled since April, 1999; five have been active users. Experience shows that the PatCIS architecture supports application integration while providing adequate security and evaluation functions. Initial caution with the patient enrollment process has limited recruitment and, consequently, usage. However, experience thus far suggests that PatCIS has good usability and utility. No adverse events, including undesirable impact on doctor-patient interactions, have been reported. There do not appear to be any technical impediments to scaling up the enrollment to continue to observe patient usage.

Computer Security↗
PubMed2000

Supracondylar fractures of the humerus in children--an epidemiological study of 132 consecutive cases.

132 consecutive cases of supracondylar fractures of the humerus admitted between July, 1997 and February, 1999 were included in a prospective study. There were 93 boys and 39 girls. The age ranges from one to 14 years old. The non-dominant arm was more often injured. Ethnic Malay constituted the majority. Accidents mainly occurred at home with a peak between 4 pm and 8 pm. Majority was presented within 24 hours of injury. Type III fracture with distal fragment in extension predominated. Nerve injuries occurred in 9 cases in which median nerve was the most commonly affected. There was only one open fracture and it was complicated by absent radial pulse and median nerve injury.

Adolescent↗
PubMed2000

Limb reconstruction surgery with external fixators--university hospital experience.

We are describing 21 limb reconstruction procedures performed in 18 patients with the use of external fixators from 1996 to 1998. The average age of patients was 21, ranging from 1 to 50 years old. Indications for surgery included short limb, non-union, pseudoarthrosis and bone or soft tissue deformities. Average length obtained for cases of limb lengthening was 6 cm. All the seven clubfoot deformities in five children were fully corrected. Equinus deformity recurred in one foot and was treated with supramalleolar osteotomy. Out of the seven cases with infected nonunion and bone loss, three failed to achieve union and required additional bone grafting procedures. One patient with unilateral external fixator for the correction of tibia shortening developed valgus deformity.

Adolescent↗