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Biomedical subjects

A Goswami

Publications and source records attributed to A Goswami.

At least 19 recordsLinked to original sources
PubMed2006

Formation of silver nanoparticles in poly(perfluorosulfonic) acid membrane.

The formation of silver nanoparticles by chemical reduction of Ag+-loaded Nafion-117 membrane with NaBH4 was studied using radioactivity tagged ions. The counterion-exchange method (Ag(m)+ <--> Na(s)+) was used to obtain a membrane sample with a varying proportion of Ag+ ions. The X-ray elemental mapping across the thickness of the membrane by energy-dispersive X-ray spectrometer attached to the environmental scanning electron microscope (ESEM/EDAX) indicated that Na+ and Ag+ were uniformly distributed in the membrane samples before reduction. The average size of nanoparticles formed after reduction was found to be 15 +/- 3 nm, irrespective of the concentration of silver ions present in the membrane before reduction. Energy-dispersive X-ray fluorescence (EDXRF) analyses of the membrane samples, carried out before and after reduction, indicated that the Ag concentration on the membrane surface was considerably increased after reduction. EDXRF measurements of the membrane samples, obtained from reduction carried out in a dead end cell, indicated that Ag nanoparticles were formed only on the membrane surface exposed to NaBH4 solution. Reduction carried out with NaBH4 tagged with 22Na showed that the formation of Ag nanoparticles involved exchange of Ag+ ions from ion-exchange sites in the interior of the membrane with Na+ ions, followed by reduction of Ag+ ions with BH4- ions at the surface of membrane. The study of self-diffusion of water, Na+, and Cs+ ions in the membrane loaded with Ag nanoparticles indicated that formation of Ag nanoparticles did not affect the diffusional transport properties of the membrane. The ion-exchange capacity and water uptake capacity were also not affected by the formation of Ag nanoparticles in the membrane. The spatial distribution of Ag nanoparticles across the thickness of the membrane obtained by ESEM/EDAX showed that Ag nanoparticles were confined to a few-micrometer surface layer of the membrane. Based on these observations, an attempt has been made to explain the mechanism of the formation of Ag nanoparticles in the membrane.

Journal Article↗
PubMed2006

Development and applications of the k0-based internal mono standard INAA method.

The k0-based internal monostandard instrumental neutron activation analysis (IM-INAA) method, developed and standardized in our laboratory, is capable of analyzing both small and large samples of different sizes and shapes. Use of in-situ relative efficiency makes the method geometry independent. In this paper, we present the development of this methodology and applications to two types of alloys namely, stainless steel and brass. A stainless steel certified reference material, BCS 466 was also analyzed to evaluate the accuracy of the method. Absolute concentrations in these alloys were arrived by a standard-less method. The method has also been applied for the analysis of large-size wheat samples (0.45-1 kg) and the results were compared with the data obtained for selected elements in sub-samples (50-1000 mg).

Journal Article↗
PubMed2003

Development of an internal monostandard instrumental neutron activation analysis method based on in situ detection efficiency for analysis of large and nonstandard geometry samples.

A k0-based internal monostandard instrumental neutron activation analysis method for determination of relative elemental concentration in samples of large size and irregular geometry has been developed. In this method, one of the elements present in the sample is used as comparator. A priori knowledge of the concentration of one of the constituents is required to convert the relative concentration into absolute values. The problems of gamma-ray self-attenuation and geometrical effects that arise in the assay of large and nonstandard geometry samples were overcome by an in situ relative detection efficiency calibration procedure, which requires one or more activation products emitting gamma-rays over a wide range of the spectrum. To minimize the problem of neutron flux perturbations that may arise in large samples, irradiations were carried out using a thermal column with thermal neutron component of more than 99.9%. The method has been standardized with samples of silica (approximately 0.5 kg) and water (0.5 L) spiked with known amounts of different elements and has been advantageously applied to some alloy and metal samples of irregular geometry, where complete compositional characterization was carried out using mass balance. This approach is highly valuable for analysis of large, irregularly shaped samples if not too high demands are set to the degree of accuracy.

Journal Article↗
PubMed2001

Biochemical approaches to the synthesis of ethyl 5-(s)-hydroxyhexanoate and 5-(s)-hydroxyhexanenitrile.

Three different biochemical approaches were used for the synthesis of ethyl 5-(S)-hydroxyhexanoate 1 and 5-(S)-hydroxyhexanenitrile 2. In the first approach, ethyl 5-oxo-hexanoate 3 and 5-oxo-hexanenitrile 4 were reduced by Pichia methanolica (SC 16116) to the corresponding (S)-alcohols, ethyl (S)-5-hydroxyhexanoate 1 and 5-(S)-hydroxyhexanenitrile 2, with an 80-90% yield and >95% enantiomeric excess (e.e). In the second approach, racemic 5-hydroxyhexanenitrile 5 was resolved by enzymatic succinylation, leading to the formation of (R)-5-hydroxyhexanenitrile hemisuccinate and leaving the desired alcohol 5-(S)-hydroxyhexanenitrile 2 with a yield of 34% (50% maximum yield) and >99% e.e. In the third approach, enzymatic hydrolysis of racemic 5-acetoxy hexanenitrile 6 resulted in the hydrolysis of the R-isomer to provide 5-(R)-hydroxyhexanenitrile, leaving 5-(S)-acetoxyhexanenitrile 7 with a 42% yield (50% maximum yield) and >99% e.e.

Journal Article↗
PubMed2001

A new spectrophotometric method for the determination of total and ferric iron in rain water at the ppb level.

A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source is described. It is based on the color reaction of Fe3+ with SCN- ions in the presence of a cationic surfactant, i.e. cetylpyridinium chloride (CPC), in strong HCl solution, and subsequent extraction of the complex with N-octylacetamide into toluene or chloroform. The apparent molar absorptivity of the complex is 2.60 x 10(5) L mol(-1) cm(-1) at lambdamax = 480 nm at an enrichment factor (EF) of 10. The detection limit (causing higher absorbance than the sum of the blank absorbance (0.009) and 3 SD) is 5 ng mL(-1) Fe. Ions commonly associated with iron did not interfere in the present method. The effect of analytical variables, i.e. amount and type of the reagents, acidity, solvent, temperature, dilution, etc., in the determination of iron are discussed. The validity of the present method is checked with GF-AAS. The method has been applied to the determination of iron at the ppb level in rain water samples.

Journal Article↗
PubMed2001

Microbial reduction of alpha-chloroketone to alpha-chlorohydrin.

Microbial reduction of alpha-chloroketone to alpha-chlorohydrin was studied as one of the approaches for construction of the chiral center of the corresponding epoxide. About 100 microorganisms covering many species of Candida, Pichia, Hansenula, Geotrichum, Rhodococcus and Aureobasidium were screened to reduce the alpha-chloroketone stereospecifically. Many strains provided the R-alpha-chlorohydrin with 100% enantiomeric excess (ee), e.g., Candida sonorensis SC 16117, Geotrichum candidum SC 5469, Rhodotorula glutinis SC 16293, Sphingomonas paucimobilis SC 16113, Pichia silvicola SC 16159 and Rhodococcus equi SC 15835. Few microorganisms showed preferential formation of S-alpha-chlorohydrin after reduction. Among them, Pichia pinus SC 13864 and two Pichia methanolica strains SC 16116 and SC 13860 were the best, providing the S-alpha-chlorohydrin with ee of 88%, 79% and 78%, respectively. The enantiospecificity of the reduction by these Pichia species can be modified by changing the pH or prior heat treatment of the cells and S-alpha-chlorohydrin with > or =95% ee was obtained by appropriate modification of reaction conditions.

Bacteria↗
PubMed2001

Review of safety in endoscopic laser foraminoplasty for the management of back pain.

OBJECTIVE: The purpose of this study was to analyze the incidence and gravity of reported complications that arise in spinal surgery and assess the comparative safety, or otherwise, of endoscopic laser foraminoplasty (ELF). BACKGROUND DATA: Chemonucleolysis, decompression, discectomy, and fusion have long been cited as treatments for chronic low back pain. Over recent years newer, less invasive surgical techniques have become available, one such being ELF. Although minimally invasive, the beneficial outcome must be interpreted in relation to concerns regarding the safety of the procedure and its risks relative to those of other forms of spinal surgery. The Spinal Foundation, Rochdale has performed 958 ELFs and has collated a comprehensive database of the results of all these operations. These prospective records provided the basis for a comparison of the safety of ELF to that reported with other spinal surgical techniques. METHODS: A total of 958 procedures have been performed on 716 patients. Complications that arose during the operation and the postoperative phase of 6 weeks following the procedure were elicited from patient records. These data were correlated and compared to a meta-analysis of randomized controlled clinical trial data of complications arising during and after conventional spinal surgery. The SPSS (statistical package for social sciences) and CIA (confidence interval analysis) statistical packages were used to draw conclusions regarding the safety of ELF. RESULTS: The cohort integrity of operation and outpatient review records at 6 weeks after surgery was 100%. In 958 ELFs performed, 24 complications occurred in 23 patients. There were 9 cases of discitis (1 infective, 8 aseptic) (0.9%), 1 dural tear (0.1%), 1 deep wound infection (0.1%), 2 patients suffered a foot drop (1 transient) (0.2%), 1 myocardial infarction (0.1%), 1 erectile dysfunction (0.1%), and 1 patient who developed panic attacks post-operatively (0.1%). This amounts to an overall surgical complication rate of 1.6%. Magnetic resonance imaging (MRI) follow up of clinically symptomatic patients highlighted 8 residual disc herniations (0.8%). Meta-analysis of randomized controlled trials of conventional spinal surgery for adult onset degenerative disc disease and/or sciatic pain reported overall complication rates for fusion (11.8%), decompression (7.6%), discectomy (6.0%), and chemonucleolysis (9.6%). CONCLUSIONS: The complication rate of ELF is shown to be significantly lower than that reported following conventional spinal surgery (p < 0.01). From these results, we conclude that ELF as a treatment for chronic low back pain and sciatica presents less risk to a patient than conventional methods of spinal surgery.

Chronic Disease↗
PubMed2001

Cervical percutaneous laser disc decompression: preliminary results of an ongoing prospective outcome study.

OBJECTIVE: This study identifies the efficacy of laser disc ablation and compares the relative efficacy of Holmium2100; YAG and KTP532 laser wavelengths in the treatment of broad-based cervical disc protrusions presenting with cervical axial pain with compressive or noncompressive radicular symptoms. BACKGROUND: A preliminary report on a prospective outcome study of cervical laser disc ablation and decompression in the management of cervical disc prolapse and discographically confirmed discogenic pain in association with radicular pain. METHODS: Patients with chronic cervical pain and radicular symptoms unresponsive to conservative treatment were assessed with magnetic resonance (MR) scans. Those with broad-based disc bulge or discal degeneration were assessed with provocative discography to isolate the source of pain. Percutaneous laser disc decompression was performed as a day case procedure on 105 patients at 108 levels under X-ray control via the anterior approach with side-firing probes in patients. RESULTS: At a minimum follow up of 24 months, 51% of patients demonstrated a sustained significant clinical benefit with an additional 25% in whom functional improvement was noted. No difference in outcome was identified either with the wavelengths used or with laser annealing or painful discal tears. The cohort integrity of the study was 80%. CONCLUSION: The sustained nature of the benefit (mean 3.5 years at final follow up) after long-term preoperative symptoms (mean 3.9 years) in 76% patients rules out placebo effect. Benefits occurred independently of the wavelength of laser used.

Adult↗
PubMed2001

Endoscopic foraminoplasty: a prospective study on 250 consecutive patients with independent evaluation.

OBJECTIVE: This study focused on the efficacy of endoscopic decompression of the foramen guided by endoscopic aware-state pain source definition. BACKGROUND DATA: Endoscopic foraminoplasty consists of undercutting of the facet joint and endoscopic discectomy, mobilization and neurolysis of the exiting and transiting nerves, and ablation of osteophytes. This study sought the outcome of endoscopic foraminoplasty in 250 consecutive patients followed for a minimum of 2 years, reviewed and assessed by an external independent assessor. It was applied to patients with back pain and sciatica in multilevel degenerative disc disease and also to those with prior surgery. METHODS: A prospective study of endoscopic laser foraminoplasty was performed on 121 males and 129 females with an average age of 48 years (21-86 years), followed for an average period of 30 months (26-43 months). The average preoperative duration of back, buttock, or leg pain was 6.1 years (5-11 years). A total of 30% had undergone prior open spinal surgery. RESULTS: The cohort integrity at follow up was 97%. Outcome was analyzed using the percentage change in Oswestry Disability Scores and visual analogue pain scores. Clinically relevant change in pain and disability was observed in 73%. Using a percentage change in Oswestry Disability Score of 50 or more to determine good and excellent outcomes, 60% of patients exceeded this score. A total of 95% patients required no further surgical intervention. CONCLUSIONS: Endoscopic laser foraminoplasty provides a minimalist means of exploring the extraforaminal zone, the foramen, the disc, and the epidural space and performing discectomy, lateral recess decompression, osteophytectomy, and neural mobilization. Performed in the aware state, it serves to identify and localize precisely the causal source of pain in multilevel disc disease, in revision surgery, and in the infirm and elderly without open fusion or decompression.

Adult↗
PubMed2001

Blood lactate concentration at selected of olympic modes weightlifting.

This study highlights the blood lactate response of weightlifters (N = 5) in two modes of olympic lifts: Snatch (SN) and Clean & Jerk (CJ), during three types of training namely (1) one repetition lift (ORL), (2) Multiple set session (MSS) and (3) one set session (OSS). In ORL, 30, 40, 50, and 60 kg, each of one repetition only, were lifted with an interval of 5 min between two consecutive loads. Both MSS and OSS consisted of 6 sets of lift: 50% x 6 (i.e. 50% of 1 Repetition Maximum x 6 repetitions), 60% x 5, 70% x 4, 80% x 3, 90% x 2, and 100% x 1. In MSS, 3 to 3.5 min interval was given between two successive sets whereas in OSS the interval was approximately 24 hours. Lactate levels were very low (< 3.5 mM) in ORL. In MSS, lactate reached peak at an intermediate set, but, it was maximum at the first set and then declined gradually in OSS. In most of the cases, however, lactate were significantly higher in CJ than SN. The study concludes that: (a) anaerobic glycolysis is not stimulated considerably when the lifting time is only 4-5 sec, (b) repetition of lift plays more important role, than intensity, in lactate production, (c) CJ is more strenuous than SN for a given %RM.

Adenosine Triphosphate↗
PubMed2001

A comparative study of cardiovascular stress during different swimming strokes.

The study was aimed: (i) to compare maximum heart rate during exhaustive running (HRmasr) and swimming (HRmaxs), (ii) to compare heart rate (HR) in various modes of swimming-front crawl (FC), butterfly (BF), breast stroke (BRS) and back stroke (BS). HRmaxr (192.3 +/- 4.9 beats/min) of the swimmers (N = 7) was higher, although not significantly (P < 0.05), than their HRmaxs (183.7 +/- 3.8). Peak HR of the swimmers in FC, BF, BRS and BS (each of 100 m distance) were 179.9 +/- 7.2, 180.3 +/- 7, 178.6 +/- 6.2 and 177.3 +/- 5.4 beats/min respectively. Average HR in the respective events were 167.3 +/- 15.8, 166.6 +/- 14.1, 163.3 +/- 13.5 and 165.8 +/- 14.6 beats/min. Differences were not significant between any two modes, either in peak HR or mean HR. The results conclude that: (i) maximum HR in swimming is approximately 8 beats/min lower than maximal running and (ii) when the effort is maximum, cardiovascular stress remains unaltered in different swimming modes.

Adult↗
PubMed2001

EMG characteristics and fibre composition: study on rectus femoris of sprinters and long distance runners.

The study was conducted on 9 sprinters and 5 long distance runners to investigate the difference in power spectral characteristics of rectus femoris muscle and the feasibility of using electromyographic techniques in categorization of muscle groups in slow dominant and fast dominant types. EMG signal was recorded, after digitization at 4 KHz, from rectus femoris muscle during isometric knee extension (at maximum voluntary contraction level) until fatigue. Digitized signal was processed for Fast Fourier Transform and Root Mean Square (RMS) voltage. Significant difference (P < 0.05) was found in RMS voltage between sprinters and long distance runners. Both groups showed decline in Mean Power Frequency (MPE) and rate of decline in sprinters was rapid. Normalized MPF showed better discrimination between the two groups. It is concluded that the EMG response observed in this study was possibly a result of differences in the muscle fibre composition of the athletes. EMG study using spectral characteristics would be useful in categorizing the sports persons in terms of suitability of the events.

Adult↗
PubMed2001

Melanotic neuroectodermal tumour of infancy: a case report.

Melanotic Neuroectodermal Tumour of Infancy is a rare tumour. Prompt recognition of such a case is essential for the Pediatric Dentist Presented here is a case of a four and a half month old child who reported in the dental out patient department of Guru Teg Bahadur Hospital with a swelling in the right anterior maxillary ridge region.

Child, Preschool↗
PubMed2000

Real-time inverse kinematics techniques for anthropomorphic limbs.

In this paper we develop a set of inverse kinematics algorithms suitable for an anthropomorphic arm or leg. We use a combination of analytical and numerical methods to solve generalized inverse kinematics problems including position, orientation, and aiming constraints. Our combination of analytical and numerical methods results in faster and more reliable algorithms than conventional inverse Jacobian and optimization-based techniques. Additionally, unlike conventional numerical algorithms, our methods allow the user to interactively explore all possible solutions using an intuitive set of parameters that define the redundancy of the system.

Algorithms↗
PubMed2000

Evaluating contraceptive choice through the method-mix approach. An Indian Council of Medical Research (ICMR) task force study.

The method-mix approach was used to evaluate informed contraceptive choices in the present study. A total of 8,077 potential clients were given a balanced presentation of all available contraceptive methods in the national program, ie, the CuT 200 intrauterine device (IUD), low-dose combined oral pills (OC), condom, and sterilization (female/male) along with a new method, Norplant(R).(1) The majority of women opted for spacing methods; among them, the IUD was preferred by about 60% of clients, followed by condoms (9%), OC (6%), and Norplant (5%). Sterilization, mainly female, was accepted by about 17% of the women making an informed choice. The economic status of couples did not influence the contraceptive choices, as all the methods were offered free of cost in the present study, which is the current practice in the national program. Illiterate women more often accepted sterilization (about 25%) than did literate women (15%). This is because illiterate women had more children; about 30% of illiterate women had three or more children, as opposed to 16.2% of literate women. However, literacy status did not influence the choice of any specific spacing method. The study also revealed that, by encouraging potential clients to make an informed choice, they could override the provider's bias while accepting a particular type of spacing method. This is evident from the observation that Norplant was the first choice of the provider for 35% of the women, whereas only 5% of women preferred and accepted Norplant. The present study stresses an urgent need to promote the practice of informed choices in the national program with a variety of contraceptive options-especially, spacing methods for improving contraceptive prevalence and reproductive health in the country.

Adolescent↗
PubMed2000

Isolation and structures of schleicherastatins 1-7 and schleicheols 1 and 2 from the teak forest medicinal tree Schleichera oleosa.

Bioassay (P-388 lymphocytic leukemia cell line)-guided separation of an extract prepared from the bark and stem of the Sri Lankan tree Schleichera oleosa led to the isolation of seven cancer cell growth inhibitory hydroxylated sterols designated schleicherastatins 1-7 (1-7) and two related sterols, schleicheols 1 and 2 (8, 9). The structure of schleicherastatin 1 (1) was completely elucidated by X-ray crystal structure determination. Based upon that defined structure, the remaining new sterol structures were deduced by highfield (300 and 500 MHz) NMR and MS interpretations. In this new series of sterols, hydroxylation at C-22 appears to be important for promoting cancer cell growth inhibition.

Antineoplastic Agents, Phytogenic↗