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S Sarkar

Publications and source records attributed to S Sarkar.

At least 415 records · Page 23Linked to original sources
PubMed1966

Properties and regulation of the beta-D-galactosidase in Shigella dysenteriae and in Escherichia coli-Shigella dysenteriae hybrids.

Sarkar, S. (Massachusetts Institute of Technology, Cambridge). Properties and regulation of the beta-d-galactosidase in Shigella dysenteriae and in Escherichia coli-Shigella dysenteriae hybrids. J. Bacteriol. 91:1477-1488. 1966.-Shigella dysenteriae strain 60 has a beta-d-galactosidase related to that of Escherichia coli but more heat-sensitive and with a turnover number about 10 times lower. Hybridization by transduction produces strains with enzymes of intermediate properties by recombination within the z gene. Both E. coli and S. dysenteriae have a regulatory i(+) gene. Recombination between i(-) mutants of the two organisms leads to restoration of the i(+) genotype. In S. dysenteriae 60, most of the i(-) mutants are subject to genetic suppression by suppressor mutations at unlinked loci. The effect of these suppressors on the products of the suppressed i(-) genes is discussed.

Centrifugation↗
PubMedDate not supplied

Etiology and management of alimentary tract ulcers in pediatric intestinal transplantation patients.

Patients who undergo intestinal transplantation encounter several complications in the posttransplant period, one of them being ulcer formation in the alimentary tract. During postoperative endoscopic monitoring of 112 pediatric intestinal transplantation patients at our institution, we identified chronic ulcer formation in 11 patients. There were no common or defining demographic or clinical variables that were found in the patients with ulcers. The ulcers could be located within the allograft or in native tissue. Biopsies were obtained from the ulcer edge and the intervening mucosa as well as an evaluation of possible infectious agents. The most common changes in the ulcers were compatible with Epstein-Barr virus-associated posttransplant lymphoproliferative disorder (PTLD; seven cases), acute rejection (six cases), and less commonly, infectious causes (one case). These changes could occur concomitantly and retrospective analysis after therapy showed that the ulcers could have multiple etiologies. Directed biopsies of ulcer edges often displayed morphological changes compatible with acute rejection of the graft, although some biopsies of the intervening mucosa did not show similar changes. Some patients treated based on the changes within the intervening mucosa responded well and led to resolution of the ulcers. Our findings demonstrate that PTLD and acute rejection are the most common causes of chronic ulcer formation and that biopsy samples should be collected simultaneously from both the ulcer edge and intervening mucosa since pathological changes can vary depending on the underlying cause(s). Infectious agents were rarely present but could be seen superimposed with the underlying cause.

Biopsy↗
PubMedDate not supplied

Synthesis and processing of RNA by isolated human placental nuclei.

Conditions for isolating intact and active nuclei from human term pacenta and for studying their transcription products are described. The isolated nuclei can synthesize cell-free RNA for a prolonged period at 29 degree C in a medium containing 100 mM KCl and 5 mM MgCl2. Actinomycin D inhibited 92 per cent of RNA synthesis, whereas approximately 60 per cent of RNA synthesis was sensitive to alpha-amanitin. When nuclei were incubated at 29 degrees C for 1 h, about 27 per cent of the newly synthesized RNA was released into the medium outside the nucleus. Analysis of this released material by affinity chromatography on an oligo(dT)-cellulose column revealed that 2.4 per cent of the total released RNA was adsorbed at high salt concentration. Most of this fraction was eluted with a low-salt buffer at 45 degrees C and the remainder by 50 per cent formamide, conditions that are necessary for elution of poly(A)-containing mRNP particles from oligo(dT)-cellulose. These results show that placental nuclei incubated in vitro synthesize poly(A)-containing RNA, which is released as a protein-bound complex. This procedure allows exploration of changes in mRNA release during placental development.

Cell Fractionation↗
PubMedDate not supplied

Evaluation and progression analysis of pulmonary tuberculosis from digital chest radiographs.

Pulmonary tuberculosis is one of the most common infections in the third world countries. We propose a method for automated evaluation and progression analysis of this disease by processing a sequence of digital chest radiographs. The presence of radiological features characteristic to pulmonary tuberculosis is detected within the regions of interest using suitable image processing and pattern recognition techniques. The detected features are then quantified to evaluate the extent of the disease. The measures are evaluated for a sequence of radiographs of a patient and are normalized with respect to rib size measures. Temporal changes in these normalized measures indicate the progression of the disease during the period in which the sequence of radiographs is obtained. The details of the proposed technique and results of analysis of a number of tuberculous patients are given in the paper.

Clavicle↗
PubMedDate not supplied

Scar assessment: current problems and future solutions.

Current problems in the assessment of scars are discussed. The concept of subjective and objective aspects of scar assessment is introduced. The patient's own view of the scar (the subjective component) can currently be assessed and may be very influential in determining the patient's quality of life, irrespective of the actual physical characteristics of the scar. The objective aspects of the scar, including size, shape, texture, and pliability, are currently difficult to measure. Although the Vancouver Scar Scale has been used as the standard for objective measurements, there are problems with both the validity and reliability of this instrument. Various imaging techniques may permit more reliable and accurate methods for measuring the quantitative aspects of scars.

Burns↗
PubMedDate not supplied

Lactate dehydrogenase activity of the rat testis treated with cyproterone acetate during fetal life.

Histological changes, total LDH activity and LDH isozyme patterns of testicular tissues of rats, exposed to cyproterone acetate during fetal life, were studied at different days after birth. While such treated testes revealed all stages of spermatogenesis and normal patterns of LDH isozymes including LDH-X bands, complete loss of isozymes was discernible in the Leydig cell fraction. It is probable that this abnormality in the Leydig cell is a consequence of impairment in the hypothalamo-hypophyseal axis or due to improper scrotal development following CA exposure.

Age Factors↗
PubMedDate not supplied

Computer-aided semen analysis variables as predictors of male fertility potential.

A computer-aided semen analysis (CASA) was used to allow digitizing the motion of the spermatozoon. This procedure allows an objective means of judging semen quality, especially the translational movements of spermatozoa. Forty-three couples were included in the study. The average age of the male was 35.5 +/- 4.7 years and that of the female was 32.7 +/- 4.7 years. The average duration of infertility was 3.8 +/- 2.3 years. Using multiple linear regression analysis of 26 prognostic variables, a cluster of 8 variables significantly predicted pregnancy maximally. The 8 variables and the resultant multiple correlation coefficients were used to generate a multiple regression equation which allowed the correct separation of the population into fertile and infertile couples. The mean pregnancy predictor values of the fertile and infertile populations were significantly different using the analysis of variance.

Adult↗
PubMedDate not supplied

Cumulative pregnancy rates and probability of pregnancy in various indications for intrauterine insemination.

A total of 122 patients were evaluated in a retrospective study for the cumulative pregnancy rate after intrauterine insemination. The indications included idiopathic infertility, anovulation, male factor, poor postcoital test, endometriosis, and pelvic factor. The cumulative pregnancy rate by 3 cycles or less varied from 7.7 to 43.5%. The highest pregnancy rate was for the group with poor postcoital test. There was no increase in pregnancy rate after 3 cycles of treatment. The concentration and motility of sperm were not significantly different between pregnant and nonpregnant groups.

Adult↗
PubMedDate not supplied

Epidemic zoster and AIDS.

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Acquired Immunodeficiency Syndrome↗