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Biomedical subjects

S Sinha

Publications and source records attributed to S Sinha.

At least 307 records · Page 17Linked to original sources
PubMed1995

Genotoxicity of the herbicide butachlor in cultured human lymphocytes.

Butachlor, a pre-emergence herbicide was investigated for its ability to induce sister chromatid exchanges (SCE) and chromosome aberrations (CA) in cultured human peripheral blood lymphocytes. Mitogen-stimulated lymphocytes were treated with three different concentrations (5, 10 and 20 micrograms/ml) of butachlor for 24, 48 and 72 h. Our results indicate a dose-dependent increase in the frequency of chromosomal aberrations at 24, 48 and 72 h of treatment with butachlor. No SCE was promoted by butachlor.

Acetanilides↗
PubMed1995

Genotoxicity of the herbicide fluchloralin on human lymphocytes in vitro: chromosomal aberration and micronucleus tests.

Cultured human lymphocytes were exposed to three different concentrations (2.5, 5.0 and 10.0 micrograms/ml) of fluchloralin for 24 and 48 h to assess chromosomal aberrations. A significant dose-dependent increase of chromatid type aberration was observed in these cells. Multiple aberrations (MA) were scored at all concentrations after 48 h treatment. To support these results we did micronucleus (MN) test using cytochalasin B to block cytokinesis. At lower concentrations (2.5 to 10.0 micrograms/ml) the frequency of MN induction was not significantly different. Higher concentrations of fluchloralin (20, 40 and 50 micrograms/ml) resulted in a significant dose dependent increase in number of micronucleated cells. This is the first report on genotoxic effects of fluchloralin in human cells.

Aniline Compounds↗
PubMed1995

Hind III genomic polymorphism of the C3b receptor (CR1) in patients with SLE: low erythrocyte CR1 expression is an acquired phenomenon.

Expression of the human erythrocyte C3b receptor (CR1-CD35) and its Hind III RFLP was studied in a group of 37 patients with SLE, 15 consanguineous relatives of the patients and 48 healthy normal subjects. The CR1 number on erythrocytes was quantitated by ELISA using a mAb to CR1. Serum levels of complement proteins (C3, C4, C3d) and circulating immune complexes (CIC) were estimated simultaneously in controls and relatives. The patients were followed up during the course of the treatment. The CR1/erythrocyte (CR1/E) in patients were found to be significantly low in comparison to controls. The gene frequencies for the alleles H and L (7.4 and 6.9 kb Hind III restriction fragments) in the patients were 0.75 and 0.25, respectively, which did not differ significantly from the controls (0.77 and 0.23 in normal subjects and 0.79 and 0.21 in consanguineous relatives of the patients). However, patients expressed fewer CR1/E within each genotype than their relatives and healthy subjects. CR/E was found to be stable in consecutive samples in controls. In patients, the numbers varied between low and high during the course of the treatment. The variation in the numbers was significantly correlated with C3d and CIC as well as with the severity of the disease. Our results suggest that low levels of CR1 on erythrocytes in SLE patients are required during the course of the disease and that the 6.9 kb restriction fragment does not play a role in causing susceptibility to the disease.

Adolescent↗
PubMed1995

Serological distinction of integral plasma membrane proteins as a class of mycobacterial antigens and their relevance for human T cell activation.

This study pertains to classification and antigenic analysis of mycobacterial plasma membrane proteins in relation to human T cell proliferative responses, using a 'fast grower' Mycobacterium fortuitum as model. Membrane vesicles, prepared by sonication and differential centrifugation, were subjected to biphasic Triton X-114 extraction for isolation of integral peripheral (aqueous phase) proteins. Neither protein pool showed any appreciable overlap serologically. SDS-PAGE showed five prominent bands in peripheral and three in the integral protein pool, whereas immunoblotting with rabbit antisera identified only two major antigens (60 and 67 kD) in the former and five (24, 34, 42, 51 and 54 kD) in the latter. ELISA with a panel of anti-mycobacterial MoAbs revealed that nine out of 12 previously known antigens were present in the peripheral protein pool. Only two of them (33 and 40 kD) were additionally detected amongst integral proteins. The membrane-associated immunosuppressive moiety lipoarabinomannan was semiquantitatively located in aqueous phase. In bulk T cell proliferation assays, seven out of 10 subjects belonging to a 'responder' background (BT-BB leprosy patients and healthy contacts) showed high responses for Myco. fortuitum antigens. Proliferative response with integral proteins was comparable to that with whole membrane, but it was significantly higher (P < 0.0005) than the response with peripheral proteins. The distinction and relevance of integral membrane proteins as a class of mycobacterial antigens make them worthy of consideration in a subunit vaccine design.

Animals↗
PubMed1995

Role of gastrografin study in the assessment of anastomotic leaks from cervical oesophagogastric anastomosis.

Gastric pull-up with cervical oesophagogastric anastomosis is a common procedure after oesophageal resection. Contrast studies are used by many surgeons for detection of anastomotic leaks but may be unnecessary. A prospective study was undertaken to compare gastrografin study and test feeding using water for detection of cervical anastomotic leaks. In 25 patients, gastrografin study showed three leaks, two of which were clinically silent and patients did not have any problems. One patient had aspiration of contrast and the study could not be completed. Two of the leaks detected clinically were missed by contrast study (one because of an incomplete study and the other was a satisfactory study). Delayed leaks occurred in two patients. All leaks healed spontaneously. A contrast study may thus be unnecessary for evaluation of a cervical oesophagogastric anastomosis and can be replaced with the simpler and safer technique of 'test feeding' using water.

Adenocarcinoma↗
PubMed1995

Noninvasive assessment of myocardial perfusion and metabolism: feasibility of registering gated MR and PET images.

OBJECTIVE: Positron emission tomography (PET), the reference technique for in vivo noninvasive assessment of myocardial perfusion and metabolism, is hampered by limited resolution and low signal-to-noise ratio. Cardiac MR imaging, on the other hand, provides excellent soft-tissue contrast. This study examines the feasibility of combining the information of these two complementary techniques by the three-dimensional superimposition of regional myocardial blood flow or substrate metabolism as depicted in cardiac PET images on comparable MR images at the same cardiac phase and spatial location. SUBJECTS AND METHODS: Three-dimensional, gated PET and MR images of the heart were acquired at different phases of the cardiac cycle from six normal volunteers and from one patient with coronary artery disease that had been detected by coronary angiography. An interactive algorithm using morphologic operators was developed to contour the left ventricle on the MR and PET images. A three-dimensional surface-fitting technique was used to register the left ventricle surfaces. The accuracy of registration was estimated using 80 internal landmarks from six volunteer scans. RESULTS: These techniques yielded PET images resliced along the same spatial location and orientation as the MR images both in the transaxial and short-axis views. The average residual, a measure of the goodness of fit, was 26 (+/- 5.6) for the systolic and 13 (+/- 6.1) for the diastolic images compared with an increase of that index from 9.3 at the best fit to 13.2 when the images were deliberately misaligned by 2 mm in each of two directions. We verified that MR and PET images could be aligned with an accuracy of 1.95 mm (+/- 1.6), which was approximately equal to the larger of the two pixel sizes (i.e., 1.6 mm on PET images). CONCLUSION: MR and PET images of the heart at identical cardiac phases can be accurately superimposed. Both transaxial and short-axis views can be obtained, the latter being more useful for PET quantification. This technique offers the potential for characterizing regional interactions among contractile function, blood flow, and substrate metabolism, especially when these are altered regionally in cardiac diseases.

Algorithms↗
PubMed1995

Immunoreactive antigens of a candidate leprosy vaccine: Mycobacterium habana.

Mycobacterium habana (M. simiae serovar-1) is a candidate vaccine for mycobacterial infections on the basis of the protection shown by this strain. We prepared 3 fractions of M. habana, i.e. the cell wall (CW), the cell membrane (CM) and the cytosol (CS). Protein antigens of these fractions were resolved by SDS-PAGE and subsequently probed with the sera of leprosy and tuberculosis patients and also antiBCG antibodies. We saw 3 major protein bands at congruent to 33 kD in the CW, congruent to 38 kD in the CM and congruent to 22 kD in the cytosol (CS) after coomassie blue staining of the gels. Pool leprosy patients' serum had identified proteins of congruent to 26 kD in CW, congruent to 35 and congruent to 18 kD in CM and congruent to 24 kD in the CS which have not been seen by the TB patient's serum pool. Pool serum of tuberculosis patients has identified 1 protein at congruent to 10 kD in the CW and a broad band between 20 and 24 kD and 1 at congruent to 4 kD in the CM which have not been visualized in the pool leprosy patient's serum lane. The proteins of M. habana which are recognized only by leprosy antisera or only by tuberculosis antisera could be exploited for developing diagnostic agents against these infections.

Antigens, Bacterial↗
PubMed1995

Adaptation of a chemiluminescent DNA detection system to strongly positively charged nylon membranes: single copy gene detection in human genome.

Nonradioactive methods for detection of genes by Southern hybridization are limited to neutral or positively charged membranes which are supplied or explicitly recommended by the manufacturers of the chemiluminescent detection systems. The results of such kits with a known strongly positively charged nylon membrane (Genescreen plus) are disappointing. The adaption of a chemiluminescent detection system to such a strongly positively charged nylon membrane is demonstrated in this communication. The modifications include a blocking step (1% SDS) before prehybridization, use of 5% SDS during hybridization, and 5% SDS and 1% BSA during detection. The increased sensitivity of such a highly positively charged nylon membrane enabled us to detect 2.5 pg of target DNA. The detection of both the alleles of a single copy polymorphic target (YNZ22) in the human genome is also shown.

Cations↗
PubMed1995

Parameter estimation of cardiac geometry by ECG-gated PET imaging: validation using magnetic resonance imaging and echocardiography.

UNLABELLED: The purpose of this study was to apply and validate a previously developed model-based image analysis technique which derives estimates of regional myocardial wall thickness and the left ventricular radius directly from gated cardiac PET images. METHODS: In 11 normal volunteers, gated myocardial 18F-deoxyglucose (FDG) images with 16 equal gates spanning the entire cardiac cycle were acquired for 20 min. To improve count statistics and thus image quality, 3 and 5 of 16 gates were summed to obtain systolic and diastolic images. Based on a five-parameter model, radial profiles from systolic and diastolic PET images were fit by nonlinear regression for myocardial wall thickness, left ventricular radius and tracer activities in the blood pool, the myocardial tissue and the extracardiac background. Echocardiography and gated magnetic resonance imaging (MRI) were performed in 11 and 7 volunteers, respectively. RESULTS: We observed a significant (p < 0.001) correlation between measurements obtained by gated PET imaging and the correlative imaging modalities for myocardial wall thickness and left ventricular radius. While good agreement was observed between measurements of average radial shortening, estimates of average wall thickening differed significantly. CONCLUSION: This model-based analysis offers accurate estimates of regional recovery coefficients directly from gated cardiac PET images and may also prove useful for the assessment of myocardial contractile function. These recovery coefficients are essential for the correction of partial volume effects when quantitative PET studies are performed.

Deoxyglucose↗