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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 811 records · Page 45Linked to original sources
PubMed1996

Efficacy and safety of repeated hepatocyte transplantation for significant liver repopulation in rodents.

BACKGROUND & AIMS: Significant liver repopulation by hepatocyte transplantation will advance clinical applications. The aim of this study was to test the hypothesis that translocation of transplanted cells into liver plates will allow repeated cell transplantation for increasing the transplanted hepatocyte mass. METHODS: Hepatocytes were transplanted via spleen from either F344 rats into syngeneic recipients deficient in dipeptidyl peptidase IV or from transgenic hepatitis B surface antigen-producing G26 mice with hepatitis B virus into nontransgenic congeneic recipients. Portosystemic shunting was shown by radiological methods. RESULTS: Repeated hepatocyte transplantation led to progressively increased liver repopulation. Transplantation of 1.75 x 10(8) hepatocytes in three divided doses repopulated more than an estimated 5% of the host rat liver, with 3.8 x 10(6) +/- 0.1 x 10(6) transplanted cells/cm3 liver. This was a tenfold or threefold mean increase in transplanted cell number compared with recipients of 2.0 x 10(7) or 7.5 x 10(7) cells transplanted in single sessions, respectively (P < 0.001). Repeated hepatocyte transplantation interfered with neither cell integrations in liver parenchyma nor secretory function of transplanted cells. Portal hypertension, portasystemic collaterals, or intrahepatic shunting were not observed in cell recipients. CONCLUSIONS: Repeated transplantation of hepatocytes in large numbers is safe and effective and should advance strategies for liver repopulation.

Animals↗
PubMed1996

Results of a prospective evaluation of three methods of management of pediatric cataracts.

BACKGROUND: Although a variety of approaches to manage cataracts in children have been studied, no consensus exists on the optimum approach. The authors, therefore, conducted a prospective, nonrandomized, consecutive study to evaluate three most commonly adopted methods of management of pediatric cataracts. METHODS: Lensectomy anterior vitrectomy (LAV), extracapsular cataract extraction with intraocular lens implantation (ECCE + IOL) and ECCE, primary posterior capsulotomy, anterior vitrectomy with IOL (ECCE + PPC + AV + IOL) were the surgical procedures performed. Aphakia in the LAV group was corrected with spectacles or contact lenses. Intraoperative and postoperative results were analyzed. Discrete variables among the three groups were compared using chi square test. RESULTS: One hundred ninety-two eyes were included in the study. There was no statistically significant difference in the intraoperative complications in the three groups. During a mean follow-up period of 11.3 months, postoperative obscuration of the visual axis was seen in 43.7% of eyes in the ECCE + IOL group and in 3.65% of eyes in the ECCE + PC + AV + IOL (p < 0.001). Two of the seven patients in the LAV group in whom contact lenses were prescribed developed corneal infiltrates. Severe postoperative anterior uveitis occurred in 15.9% and 13.8% of eyes in the ECCE + PPC + AV + IOL and ECCE + IOL groups, respectively. None of the eyes that underwent LAV developed this complication (P < 0.001). There was no statistically significant difference in the incidence of retinal detachment, endophthalmitis, or glaucoma in the three groups. CONCLUSION: Of the three approaches, ECCE + PPC + AV + IOL was conducive to at least short-term maintenance of a clear visual axis, provided optimum refractive correction, and was not associated with increased risk of short-term complications. Continued follow-up of these eyes is necessary to conclude on the long term results of this technique.

Cataract↗
PubMed1996

Enlarged blind spots in chorioretinal inflammatory disorders.

PURPOSE: This study was undertaken to better characterize patients with multifocal choroiditis and panuveitis (MCP), punctate inner choroidopathy (PIC), multiple evanescent white dot syndrome (MEWDS), and diffuse subretinal fibrosis syndrome. The specific aim was to determine whether these disorders were different entities or part of a spectrum of diseases with similar features. METHODS: Seventy-nine patients were included in this study. Most of the patients have been followed up prospectively since July 1980 with some found retrospectively. RESULTS: Forty-one patients had MCP, 16 had PIC, 6 had diffuse subretinal fibrosis syndrome, and 16 had MEWDS. Patients with MCP had visual loss and visual field defects caused directly by visible lesions or recurrent inflammation around old lesions. In particular, clustering of lesions around the optic nerve and nasal periphery was seen in patients with MCP and appeared to be related to visual field loss. Patients with PIC also had enlarged blind spot and other field defects explained by fundus lesions. Patients with PIC and MCP did not have recurrent lesions on extended follow-up. Patients with diffuse subretinal fibrosis syndrome represented a subset of patients characterized with lesions in the posterior pole, sever scarring, and visual loss. Patients with MEWDS had the least inflammation with symmetrically distributed lesions. Minimal permanent chorioretinal scarring was seen in patients with MEWDS. Visual field defects improved in most patients with MEWDS and PIC, whereas most patients with MCP and diffuse subretinal fibrosis syndrome did not improve. CONCLUSIONS: Although enlarged blind spots are a feature of all four disorders, other clinical, angiographic, and electroretinographic evidence suggest that these are different entities.

Adolescent↗
PubMed1996

Presumed noninfectious endophthalmitis after cataract surgery.

PURPOSE: To study the clinical features and results of conservative management in cases of presumed noninfectious endophthalmitis after cataract surgery. SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: This retrospective study evaluated cases of presumed noninfectious endophthalmitis occurring after cataract surgery in a hospital-based population. Patients with minimal hypopyon and decreased visual acuity unassociated with pain, lid edema, conjunctival chemosis, corneal abscess, and obvious vitreous involvement were treated conservatively. The mainstays of treatment were topical and systemic steroids. Four eyes with clinical evidence of worsening required surgical intervention. Main outcome measures were resolution of inflammation and final visual acuity. RESULTS: In 23 of 27 patients, the inflammation resolved with medical therapy alone; 21 had a final visual acuity of 20/50 or better. In 3 of the 4 eyes that had surgery, the culture was positive for low virulent organisms; all had a satisfactory outcome. One eye with preoperative glaucoma developed absolute glaucoma with resolution of inflammation. CONCLUSION: Noninfectious endophthalmitis invariably presents with hypopyon and decreased vision unassociated with pain and lid edema. A trial of medical therapy with corticosteroids as the mainstay of treatment is often rewarding. Frequent monitoring and preparation for surgical intervention if required are key.

Adolescent↗
PubMed1996

Chemoprevention of carcinogen-DNA binding: the relative role of different oxygenated substituents on 4-methylcoumarins in the inhibition of aflatoxin B1-DNA binding in vitro.

Eighteen 4-methylcoumarins bearing methoxy/hydroxy/acetoxy functionalities have been reported to effectively inhibit the rat liver microsome-mediated aflatoxin B1-DNA binding in vitro. The contribution of functionality on coumarin nucleus towards the inhibition of AFB1-DNA binding is in the order acetoxy > hydroxy > methoxy. The results illustrate the structure-activity relationship.

Aflatoxin B1↗
PubMed1996

Surgical management of corrosive strictures following acid burns of upper gastrointestinal tract.

OBJECTIVE: Acid burns of the upper gastrointestinal tract produce a complex combination of lesions which can be grouped into five types, and existing surgical techniques have proved inadequate in treating some of these lesions. METHODS: Over the past 25 years 72 patients have needed operative treatment since they could not be managed by more conservative measures; the anatomical lesions in the five types and their surgical management are described. RESULTS: There were two early and one late death and morbidity was low in the long-term follow-up examinations, which included gastric secretory functions, transit time estimation with gamma camera and contrast radiography. CONCLUSIONS: The conclusions are 1) a variable approach is needed for each individual patient, 2) the right colon has proved suitable for esophageal bypass, 3) the ileum is included, when necessary, by making a side-to-side ileocaecoplasty to make it into a straight conduit and eliminate the caecal bulk and ileocaecal valve, 3) augmentation gastroduodenoplasty using a split jejunum or colon is very satisfactory for reconstructing a burnt contracted stomach, 4) posterior colopharyngeal anastomosis, performed as a pharyngoplasty by excising or widely incising the fibrosed posterior wall of the pharynx, restores normal deglutition, 5) parenteral vitamin B12 replacement is necessary in severe gastric burns.

Acids↗
PubMed1996

The maintenance of strain structure in populations of recombining infectious agents.

Using mathematical models that combine population genetic and epidemiological processes, we resolve the paradox that many important pathogens appear to persist as discrete strains despite the constant exchange of genetic material. We show that dominant polymorphic determinants (that is, those that elicit the most effective immune responses) will be organized into nonoverlapping combinations as a result of selection by the host immune system, thereby defining a set of discrete independently transmitted strains. By analysing 222 isolates of Neisseria meningitidis, we show that two highly polymorphic epitopes of the outer membrane protein PorA exist in nonoverlapping combinations as predicted by this general framework. The model indicates that dominant polymorphic determinants will be in linkage disequilibrium, despite frequent genetic exchange, even though they may be encoded by several unlinked genes. This suggests that the detection of nonrandom associations between epitope regions can be employed as a novel strategem for identifying dominant polymorphic antigens.

Genes, Dominant↗
PubMed1996

Phyllanthus amarus down-regulates hepatitis B virus mRNA transcription and replication.

The Phyllanthus amarus plant shows potential for treating hepatitis B virus. To define the mechanism of action of P. amarus, we used HepG2 2.2.15 cells, which support hepatitis B virus replication. P. amarus inhibited hepatitis B virus polymerase activity, decreased episomal hepatitis B virus DNA content and suppressed virus release into culture medium. To examine transcriptional control mechanisms, we used G26 hepatitis B virus transgenic mice, which produce serum HBsAg but neither HBcAg nor virion particles. When P. amarus was administered to transgenic mice, hepatic HBsAg mRNA levels decreased, indicating transcriptional or post-transcriptional down-regulation of the transgene. Increase in hepatitis B virus mRNA expression after stimulation of the glucocorticoid responsive element was also suppressed by P. amarus, suggesting involvement of the hepatitis B virus enhancer in this response. Disruption by P. amarus of hepatitis B virus polymerase activity, mRNA transcription and replication supports its role as an antiviral agent.

Animals↗
PubMed1996

Comparative study of lactate removal in short term massage of extremities, active recovery and a passive recovery period after supramaximal exercise sessions.

This investigation highlights the comparison of blood lactate removal during the period of recovery in which the subjects were required to sit down as a passive rest period, followed by active recovery at 30% VO(2)max and short term body massage, as the three modes of recovery used. Ten male athletes participated in the study. Exercise was performed on a bicycle ergometer with loads at 150% VO(2)max, each session lasting 1 min, interspaced with 15 sec rest periods, until exhaustion. Blood lactate concentration was recorded at recovery periods of 0,3, 5, 10, 20, 30, and 40 min, while VO(2), VCO(2) and heart rate were recorded every 30 sec for 30 min. The highest mean lactate value was found after 3 min of recovery irrespective of the type of modality applied. Significantly lower half life of lactate was observed during active recovery (15.7 +/- 2.5 min) period, while short term massage as a means of recovery required 21.8 +/- 3.5 min and did not show any significant difference from a passive type of sitting recovery period of 21.5 +/- 2.8 min. Analysis of lactate values indicated no remarkable difference between massage and a passive type of sitting recovery period. It was observed that in short term massage recovery, more oxygen was consumed as compared to a passive type of sitting recovery. It is concluded from the study that the short term body massage is ineffective in enhancing the lactate removal and that an active type of recovery is the best modality for enhancing lactate removal after exercise.

Adult↗
PubMed1996

Interactions of trans-acting factor(s) with the estradiol response element and nuclear factor 1 of the vitellogenin II gene of Japanese quail.

This study was directed at achieving an understanding of the mechanisms by which steroid hormones control the synthesis of vitellogenin (VTG) protein in the liver of the Japanese quail. Northern hybridization shows that administration of estradiol alone or with progesterone stimulates the synthesis of VTG mRNA. Gel mobility shift assay of DNA fragments containing the ERE and NF 1 shows that estradiol alone or with progesterone increases the levels of nuclear proteins that bind to these cis-acting elements of the promoter of the VTG gene. The cooperative effect of the two hormones seen at the level of expression of the VTG gene may be due to protein-protein interactions of trans-acting factors that bind to ERE and NF 1.

Animals↗
PubMed1996

Regulation of protein kinase C isoforms in FRTL-5 thyroid cells by TSH and phorbol ester.

Activation of protein kinase C (PKC) has been observed following TSH exposure in FRTL-5 thyroid cells. However, PKC exists as a family of isoforms displaying individual characteristics. Recently, Wang et al. identified alpha-, delta-, epsilon-, and zeta-PKC in FRTL-5 thyroid cells chronically exposed to TSH. To determine if these PKC isoforms are regulated by TSH, we examined PKC isoforms by Western blotting in FRTL-5 thyroid cells after depletion of TSH followed by short-term TSH exposure (100 microU/mL; 30 min). Phorbol 12-myristate 13-acetate (PMA; 100 nM, 10 min) served as a positive control. In untreated cells, alpha-, epsilon-, and zeta-PKC isoforms were identified in both cytosolic and membrane fractions. Using the specific antigenic peptide to the respective PKC isoforms identified, each band could be appropriately displaced. PMA caused the translocation of alpha-PKC from the cytosol to the membrane-bound fraction. Although membrane-bound epsilon-PKC and zeta-PKC were increased following PMA exposure, the cytosolic fraction was unaffected. TSH had no effect on the cytosolic fractions of any of the PKC isoforms identified but was able to increase the membrane-bound fractions of alpha-, epsilon-, and zeta-PKC. Although delta-PKC was observed in FRTL-5 thyroid cells cultured in TSH-supplemented medium, delta-PKC disappeared within 24 h of TSH depletion and reappeared 24 h after TSH reexposure with further increases up to 72 h. These studies indicate that the PKC isoforms present in FRTL-5 thyroid cells are regulated by both phorbol ester and TSH and that the duration of TSH exposure differentially regulates delta-PKC. These observations provide further evidence that PKC is a mediator of TSH action in FRTL-5 thyroid cells in vitro.

Blotting, Western↗
PubMed1996

Percutaneous balloon mitral valvotomy in mitral restenosis.

BACKGROUND: Mitral restenosis often occurs within 5 to 15 years of surgical valvotomy. Percutaneous balloon mitral valvotomy is well established as a safe and effective alternative to mitral stenosis surgery, but only a few small studies have reported on the procedure. AIM: (i) To evaluate the safety and efficacy of percutaneous balloon mitral valvotomy in patients with mitral restenosis. (ii) To evaluate the intermediate-term outcome of patients undergoing balloon mitral valvotomy after previous surgical valvotomy. (iii) To compare these patients with those undergoing balloon mitral valvotomy as the initial procedure. METHODS: We analysed our experience of 614 consecutive patients undergoing balloon valvotomy and identified 84 patients (13.7%) with mitral restenosis following prior surgical valvotomy (Group I). The remaining 530 patients (86.3%) had not undergone previous surgery (Group II). The incidence of atrial fibrillation (19% vs 5.6%), mitral valve calcification (50% vs 30.6%) and total echo score > 8 (54.8% vs 24.15%) was significantly higher in Group I. Both groups were comparable as regards their functional class, technique of valvotomy, mitral valve area (0.87 +/- 0.18 vs 0.87 +/- 0.15 cm2, P = ns), mean transmitral gradient (19.63 +/- 6.01 vs 19.21 +/- 5.67 mmHg, P = ns), and mean pulmonary artery pressure (42.2 +/- 19.0 vs 40.8 +/- 14.4 mmHg, P = ns). RESULTS: After percutaneous balloon mitral valvotomy, the final mitral valve area (1.67 +/- 0.28 vs 1.69 +/- 0.29 cm2, P = ns), mean transmitral-mitral gradient (6.12 +/- 3.68 vs 5.02 +/- 3.21 mmHg, P = ns) and mean pulmonary artery pressure (31.0 +/- 15.2 vs 28.5 +/- 11.1 mmHg, P = ns) were comparable. The success rate (93.0% vs 95.3%, P = ns) were similar in both groups. Significant mitral regurgitation was seen in four (4.8%) patients in Group I and 22 (4.1%) patients in Group II (P = ns). There were two deaths (2.4%) in Group I and five (0.9%) in Group II (P = ns). The clinical and echo Doppler follow-up (8-40 months) studies showed that both groups were of similar NYHA class, and had similar mitral valve area (1.65 +/- 0.21 vs 1.66 +/- 0.3 cm2) and transmitral gradients (7.1 +/- 3.8 vs 5.9 +/- 3.5 mmHg). CONCLUSION: We conclude that percutaneous balloon mitral valvotomy can be performed safely and effectively in patients with mitral restenosis following surgical valvotomy; the beneficial acute outcome is sustained, as shown at intermediate-term follow-up and is similar to that of patients undergoing balloon mitral valvotomy as an initial procedure.

Adult↗
PubMed1996

Urinary tract infection in nephrotic syndrome.

BACKGROUND: The aim was to study the frequency, etiology and predisposing factors of urinary tract infection (UTI) in children with nephrotic syndrome. METHODS: A retrospective analysis of all children with nephrotic syndrome was made to determine the occurrence of infectious complications. RESULTS: UTI was found to be the most common infection (40.26%); 49 episodes of culture-positive UTI were observed in 37 children. All 49 episodes occurred in patients who were initially considered to be steroid nonresponders or in relapse. Fourteen of the 49 episodes (28.6%) were asymptomatic. One child had Grade IV reflux and another had a ureteric calculus. The majority of the children had no underlying urinary tract malformations. The children with UTI had significantly lower serum albumin (P < 0.05) and higher serum cholesterol (P < 0.001) concentrations than the group of 206 children without infections. Non-Escherichia coli organisms accounted for 39% of the culture isolates. CONCLUSIONS: We believe that UTI is an important but often underdiagnosed infection in children with nephrotic syndrome.

Adolescent↗