Search PubMed⌕ Search

Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 307 records · Page 17Linked to original sources
PubMed2001

Rapid non-destructive quantitative estimation of urania/thoria in mixed thorium uranium di-oxide pellets by high-resolution gamma-ray spectrometry.

A non-destructive technique using high-resolution gamma-ray spectrometry has been standardised for quantitative estimation of uranium/thorium in mixed (ThO2-UO2) fuel pellets of varying composition. Four gamma energies were selected; two each from the uranium and thorium series and the time of counting has been optimised. This technique can be used for rapid estimation of U/Th percentage in a large number of mixed fuel pellets from a production campaign.

Radiation Monitoring↗
PubMed2001

Applications of retrotransposons as genetic tools in plant biology.

Retrotransposons are mobile genetic elements that accomplish transposition via an RNA intermediate that is reverse transcribed before integration into a new location within the host genome. They are ubiquitous in eukaryotic organisms and constitute a major portion of the nuclear genome (often more than half of the total DNA) in plants. Furthermore, they are dispersed as interspersed repetitive sequences throughout most of the length of all host chromosomes. These unique properties of retrotransposons have been exploited as genetic tools for plant genome analysis. Major applications are in determining phylogeny and genetic diversity and in the functional analyses of genes in plants. Here, recent advances in molecular markers, gene tagging and functional genomics technologies using plant retrotransposons are described.

Genetic Linkage↗
PubMed2001

The effect of modifiers on the fluorescence and life-time of Gd3+ ions doped in borate glasses.

The effect of glass modifiers on the fluorescence and life time of the 6P(7/2) energy state of the Gd3+ ion has been investigated. A shift in the energy of maximum of the fluorescence has been observed. The results are explained on the basis of the relative cation and anion field strengths due to modifiers. A variation in the life-time of the 6P7.2 energy state of the Gd3 ion has also been noted.

Borates↗
PubMed2001

Towards elimination of lymphatic filariasis in India.

The global initiatives to eliminate lymphatic filariasis as a public health problem by the year 2020 have generated a great deal of debate in India, the largest endemic country. This has led to a shift in the focus from control to elimination of the disease. Although the campaign to eliminate filariasis has begun, much more needs to be done. Several recent research studies have provided an insight into various operational issues and prospects of elimination of lymphatic filariasis. In this article, the current scenario, recent research results, logistics and the prospects of eliminating lymphatic filariasis in India will be discussed.

Animals↗
PubMed2001

Locating, characterizing and minimizing sources of error for a paper case-based structured oral examination in a multi-campus clerkship.

OBJECTIVE: To determine consistency of assessment in a new paper case-based structured oral examination in a multi-community pediatrics clerkship, and to identify correctable problems in the administration of examination and assessment process. METHOD: Nine paper case-based oral examinations were audio-taped. From audio-tapes five community coordinators scored examiner behaviors and graded student performance. Correlations among examiner behaviors scores were examined. Graphs identified grading patterns of evaluators. The effect of exam-giving on evaluators was assessed by t-test. Reliability of grades was calculated and the effect of reducing assessment problems was modeled. RESULTS: Exam-givers differed most in their "teaching-guiding" behavior, and this negatively correlated with student grades. Exam reliability was lowered mainly by evaluator differences in leniency and grading pattern; less important was absence of standardization in cases. CONCLUSIONS: While grade reliability was low in early use of the paper case-based oral examination, modeling of plausible effects of training and monitoring for greater uniformity in administration of the examination and assigning scores suggests that more adequate reliabilities can be attained.

Clinical Clerkship↗
PubMed2001

Clinical and molecular studies of a large family with desmin-associated restrictive cardiomyopathy.

Patients with restrictive cardiomyopathy (RC) have impaired diastolic function, but intact systolic function until later stages of the disease, ultimately leading to heart failure. Primary RC is often sporadic, but also may be inherited in an autosomal dominant fashion, particularly the idiopathic forms. Recently there has been great interest in inherited cardiomyopathy associated with myocyte desmin deposition ('desminopathies'). In some such families, desmin or alpha-B crystallin gene mutation is the underlying cause, and the desmin accumulation affects skeletal muscle as well, usually causing skeletal myopathy. We describe a large family with apparent autosomal dominant inheritance of desmin-associated RC spanning four generations, with the age of onset and severity/rate of progression being highly variable. This family is relatively unique in that there is no symptom-based evidence of skeletal muscle involvement, and the known desminopathy and cardiomyopathy genes/loci have been ruled out. These data support literature suggesting that desmin deposition may be associated with different underlying gene defects, and that a novel desminopathy gene is responsible for the condition in this family.

Adolescent↗
PubMed2001

Sequential anastomosis of accessory renal artery to inferior epigastric artery in the management of multiple arteries in live related renal transplantation: a critical appraisal.

In live related renal transplant program, management of multiple renal arteries (MRA) is technically demanding and used to be considered a relative contraindication because of increased risk of vascular and urologic complications. We present a retrospective analysis of the outcome of grafts with MRA and suggest certain guidelines. Of the 680 live related kidney transplantations done, 53 allografts had MRA. Cases were grouped according to the reconstruction technique: group A, MRA reconstructed ex vivo into a single renal artery (n=27); group B, MRA with multiple anastomoses in vivo (n =13); group C, MRA with sequential revascularization using inferior epigastric artery (n=11). We compared serum creatinine, acute tubular necrosis, rejection rates and the rewarm ischemia time between the three groups. Overall patient survival and graft survival were excellent (100 and 96%). Mean serum creatinine at 1 yr did not differ significantly between the three groups. Rewarm ischemia time was significantly less in group C (p<0.01). Incidence of acute tubular necrosis and rejection episodes was also less in group C although the difference was statistically significant only between group C and group B. We conclude that allografts with MRA can be used successfully in a live related renal transplantation program. Bench reconstruction should be done whenever possible. For reconstruction of an accessory vessel, inferior epigastric artery with sequential revascularization is recommended.

Adolescent↗
PubMed2001

Cyclosporin A withdrawal in live related renal transplantation: long-term results.

Cyclosporin A (CsA) withdrawal after 1 yr of stable graft function has been shown to be beneficial in cadaveric renal transplantation. This strategy could be even more suitable for 'immunologically advantaged' grafts as in live related renal transplantation. We report the long-term outcome of patients in a live related transplantation programme undergoing early (between 1989 and 1992) and late (1993 onwards) CsA withdrawal as compared with those on long-term low dose CsA (1993 onwards). Two-hundred and fifty-two patients were divided into three groups based on the following immunosuppressive protocol: group ECyW (n=99), early CsA withdrawal (9 months after transplantation); group LCyW (n=44), late CsA withdrawal (median 16 months, range 13--22 months after transplantation); and group LDCy (n=109), long-term low dose CsA. The median period of follow-up was 66 months after transplantation (range 43--84 months). There was no difference in the actuarial 6-yr patient or graft survival among the three groups. Acute rejection episodes were more frequent in ECyW (54.4%) than in LDCy (31.8%) and LCyW (23.8%) (p=0.001). The risk of developing late (> or =9 months) acute rejection was highest in ECyW 32/99 (32.3%) as compared with LCyW 8/44 (18.4%; p=0.08) and LDCy 8/109 (7.3%; p=0.0001). Of the 32 ECyW patients who developed acute rejection episodes after CsA withdrawal, 13 (40.6%) lost their grafts either due to uncontrolled acute rejection or to chronic rejection. Chronic rejection was higher in ECyW (24%) than in LCyW (11%; p=0.04) and LDCy (17%; p=0.17). Antihypertensive requirement was highest in patients maintained on low dose CsA. Graft function, as measured by serum creatinine levels, was significantly better in LCyW (1.24+/-0.4 mg%) as compared with ECyW (1.49+/-0.5 mg%) and LDCy (1.48+/-0.6 mg%). Early CsA withdrawal after live related renal transplantation is associated with a significant risk of acute rejection and subsequent chronic rejection. Slow withdrawal after 1 yr is safe and more economical than the long-term administration of low dose CsA.

Acute Disease↗
PubMed2001

Effect of lovastatin, an HMG CoA reductase inhibitor, on acute renal allograft rejection.

3-Hydroxy-3-methyl glutaryl coenzyme A (HMG CoA) reductase inhibitors are established anti-lipidemic agents. They also exert immunomodulatory effects. Two recent reports suggest that pravastatin may be useful in decreasing the incidence and severity of acute rejections (ARs) in heart and kidney transplant recipients. We undertook this prospective, randomized, placebo-controlled, double blind trial to investigate the effect of lovastatin on acute renal allograft rejection. Sixty-five consecutive, one-haplotype-matched, living related first renal transplant recipients were randomized to receive either lovastatin 20 mg/d or placebo for 3 months, in addition to cyclosporine, azathioprine, and steroids. Lipid levels, AR episodes, and liver and muscle enzymes were followed for 3 months post-transplant. At the end of the study period, lovastatin had successfully controlled lipid levels. However, there was no effect on AR episodes (15.15% in the treatment group vs. 18.75% in the placebo group).

Adult↗
PubMed2001

Comparative study of vitrectomy for dropped nucleus with and without the use of perfluorocarbon liquid. Clinical, electrophysiological and visual field outcomes.

PURPOSE: To compare pars plana vitrectomy for dropped nucleus with and without perfluorocarbon liquid. METHODS: 24 eyes with dropped nucleus were randomized to undergo PPV with perfluorodecalin, (study, n=12) and without it (control, n=12). Visual acuity, IOP, visual evoked response and electroretinography were noted at study entry and up to 3 months after PPV. Humphrey perimetry was done at 3 months. RESULTS: Final visual acuity was >20/60 in 75% of study eyes and 41.6% of controls. The two groups were statistically comparable with regard to the above parameters before PPV and during follow-up. The timing of vitrectomy did not significantly influence the final visual acuity. A higher rate of complications was seen in the control group. CONCLUSIONS: Perfluorodecalin facilitated the procedure and possibly minimized complications, and was found to be safe for intraoperative use in terms of recovery of visual acuity, stable ERG and VER, and normal visual fields.

Adult↗
PubMed2001

Emerging technologies in yeast genomics.

The genomic revolution is undeniable: in the past year alone, the term 'genomics' was found in nearly 500 research articles, and at least 6 journals are devoted solely to genomic biology. More than just a buzzword, molecular biology has genuinely embraced genomics (the systematic, large-scale study of genomes and their functions). With its facile genetics, the budding yeast Saccharomyces cerevisiae has emerged as an important model organism in the development of many current genomic methodologies. These techniques have greatly influenced the manner in which biology is studied in yeast and in other organisms. In this review, we summarize the most promising technologies in yeast genomics.

Binding Sites↗
PubMed2001

Amyloid and nonfibrillar deposits in mice transgenic for wild-type human transthyretin: a possible model for senile systemic amyloidosis.

The human serum protein transthyretin (TTR) is highly fibrillogenic in vitro and is the fibril precursor in both autosomal dominant (familial amyloidotic polyneuropathy [FAP] and familial amyloidotic cardiomyopathy [FAC]) and sporadic (senile systemic amyloidosis [SSA]) forms of human cardiac amyloidosis. We have produced mouse strains transgenic for either wild-type or mutant (TTRLeu55Pro) human TTR genes. Eighty-four percent of C57BI/6xDBA/2 mice older than 18 months, transgenic for the wild-type human TTR gene, develop TTR deposits that occur primarily in heart and kidney. In most of the animals, the deposits are nonfibrillar and non-Congophilic, but 20% of animals older than 18 months that bear the transgene have human TTR cardiac amyloid deposits identical to the lesions seen in SSA. Amino terminal amino acid sequence analysis and mass spectrometry of the major component extracted from amyloid and nonamyloid deposits revealed that both were intact human TTR monomers with no evidence of proteolysis or codeposition of murine TTR. This is the first instance in which the proteins from amyloid and nonfibrillar deposits in the same or syngeneic animals have been shown to be identical by sequence analysis. It is also the first time in any form of amyloidosis that nonfibrillar deposits have been shown to systematically occur temporally before the appearance of fibrils derived from the same precursor in the same tissues. These findings suggest, but do not prove, that the nonamyloid deposits represent a precursor of the fibril. The differences in the ultrastructure and binding properties of the deposits, despite the identical sizes and amino terminal amino acid sequences of the TTR and the dissociation of deposition and fibril formation, provide evidence that in vivo factors, perhaps associated with aging, impact on both systemic precursor deposition and amyloid fibril formation.

Aging↗
PubMed2001

Evaluation of haloperidol--ketamine mixture (1:1) anaesthesia in dogs.

Four clinically healthy dogs of either sex, aged 3-5 years, weighing between 9 and 18 kg and maintained under uniform management conditions, were administered haloperidol (5 mg/ml) and ketamine (50 mg/ml) intravenously in 1:1 ratio until the pedal reflex was lost. The calculated doses of haloperidol and ketamine were 1.71 and 17.05 mg/kg body weight intravenously, respectively. Corneal and palpebral reflexes were maintained although pain reflexes were absent up to 20 min of the cocktail administration. The induction of anaesthesia was quick and smooth. There was moderate to good muscle relaxation and analgesia. Mean arterial and central venous pressures and tidal volume decreased significantly (P < 0.05) from baseline values. Significant tachycardia and hyperglycemia were observed.

Anesthetics, Combined↗
PubMed2001

Feasibility of day-care open cholecystectomy: evaluation in an inpatient model.

BACKGROUND: Open cholecystectomy is still a fairly frequently performed operation worldwide, and is used where laparoscopic surgery has failed or is contraindicated, and where some surgeons do not operate laparoscopically for technical reasons. In developing countries laparoscopic cholecystectomy is costly and is available only in a few centres. The present study was conducted to assess the feasibility of day-care open cholecystectomy using an inpatient model. METHODS: Thirty patients were subjected to open cholecystectomy. Intraoperative nasogastric decompression and local wound infiltration with 0.25% bupivacaine was carried out. Postoperatively patients were encouraged to be ambulant, pass urine and start oral fluids. Intravenous fluids and parenteral medication were stopped at 8 p.m. when patients were assessed for feasibility for discharge. All patients were reassessed the next morning for any adverse effects that could have occurred had the patients been discharged on the evening of surgery. RESULTS: Prospectively, 73.3% of patients were considered to be dischargeable on the evening of surgery; but on reassessment the next morning, retrospectively, 93.3% of patients were actually dischargeable on the evening of surgery. A total of 76.6% of patients was actually discharged within 24 h of surgery. No patient required readmission. On follow up there were no complications that could be attributable to early discharge. A total of 83.3% of patients approved of day-care open cholecystectomy. CONCLUSIONS: Day-care open cholecystectomy is safe and feasible. In developing countries, where the use of laparoscopic surgery is limited due to resource constraints, day-care open cholecystectomy can lead to substantial savings in health-care resources.

Adult↗
PubMed2001

Determinants of pancreaticoenteric anastomotic leak following pancreaticoduodenectomy.

BACKGROUND: The purpose of the present paper was to study the incidence, presentation and management of pancreaticoenteric anastomotic (PEA) leak following pancreaticoduodenectomy (PD) and to identify risk factors associated with PEA leak. METHODS: One hundred and twenty patients underwent PD for benign and malignant pancreatic and periampullary lesions from 1989 to 1998. Prospectively collected data were analysed for incidence and outcome of PEA leak. Four clinical, three laboratory parameters, preoperative biliary drainage (PBD), perioperative octreotide use, nine intraoperative parameters, site of tumour and stage of malignant tumours were analysed by univariate and multivariate logistic regression analysis to identify factors influencing PEA leak. RESULTS: Pancreatic leak developed in 15 (12.5%) patients. Nine patients (60%) had a PEA leak that manifested as controlled leak through the drain. All were managed conservatively and the leak stopped after a mean duration of 17 days (range: 6-32 days). Six (40%) patients had associated intra-abdominal complications, and three (50%) died in the postoperative period. Pancreatic fistula healed in the three remaining patients after a mean duration of 18 days (range: 15-25 days). Diabetes (P = 0.02; odds ratio (OR) = 4.60; 95% confidence interval (CI): 1.23-17.18), PBD (P = 0.03; OR = 4.82; 95% CI: 1.21-19.24), sequence of reconstruction (bilioenteric anastomosis as first anastomosis; P = 0.01; OR = 6.25; 95% CI: 1.45-26.83) and duration of surgery > 8 h (P = 0.01; OR: 5.61; 95% CI: 1.54-20.39) were associated with a significantly higher incidence of PEA leak. CONCLUSION: Pancreaticoenteric anastomotic leak occurred in 12% of patients undergoing PD for pancreatic and periampullary tumours. The majority of these were uncomplicated and healed with conservative treatment. Complicated leaks were associated with high mortality. Diabetes mellitus, PBD, prolonged surgery and the sequence of reconstruction were risk factors associated with an increased incidence of PEA leak.

Adult↗