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Biomedical subjects

V Mehta

Publications and source records attributed to V Mehta.

54 records · Page 3Linked to original sources
PubMed1990

Regulation of expression of TL genes of the mouse Mhc.

The expression of thymus leukemia (TL) antigens and genes in thymocytes and activated T cells was examined by immunoprecipitation, flow cytometric, northern, and nuclear run-off transcription analyses. Cell surface forms of TL were detectable by immunoprecipitation on activated peripheral T cells from Tla haplotypes except Tla(b), in agreement with expression observed on thymocytes. Approximately 40%-50% of concanavalin A (Con A) or anti-CD3-activated T cells were TL+, with expression detected on both the CD4 and CD8 subsets by dual-color analysis. Activated T cells expressed detectable levels of TL mRNA 48 h after stimulation, but no TL transcripts were detectable in unstimulated splenocytes. However, TL mRNA expression in mature activated T cells did not precisely mimic thymocyte expression: the level of expression was considerably lower in activated T cells, and in most haplotypes the transcripts produced in activated T cells appeared to represent a subset of the transcripts produced in thymocytes. By run-off transcription assays in isolated nuclei, TL gene expression was detected in activated but not resting T cells indicating that lack of expression of TL in resting T cells is not due to message instability. These data demonstrate that TL genes are inducible and transcriptionally regulated.

Animals↗
PubMed1990

Biochemical differences in Qa-2 antigens expressed by Qa-2+,6+ and Qa-2+,6- strains. Evidence for differential expression of the Q7 and Q9 genes.

Cell surface forms of Qa-6 class I molecules are biochemically indistinguishable from Qa-2 although Qa-6 maps telomeric to Qa-2 with the recombinant strain B6.K2. Analysis of appropriate F1 strains did not demonstrate the presence of a trans acting factor that could modify the Qa-2 molecule to produce the Qa-6 determinant. Also, neither a neighboring cell surface molecule nor oligosaccharides were found to block the recognition of the Qa-6 determinant in Qa-2+,6- strains. The 2-D gel profiles of neuraminidase or endoglycosidase treated anti-Qa-2 immunoprecipitates from lysates of cell surface iodinated Qa-2+,6+ strains revealed an additional basic polypeptide which was absent from that of Qa-2+,6- strains. Thus, differential sialylation/glycosylation of Qa-2 molecules masks detection of Qa-2 antigen heterogeneity when cell surface forms are analyzed. Qa-6+ phenotype associated polypeptides were also found at various stages of post-translational processing in cells metabolically labeled in the presence and absence of tunicamycin. Northern analyses using Q7 and Q9 specific oligonucleotide probes revealed appropriate sized transcripts for both genes in the Qa-2+,6+ strain B6 but only Q9 in the Qa-2+,6- strain B6.K2. These data demonstrate that there is structural heterogeneity in Qa-2 antigens expressed by Qa-2+,6+ and Qa-2+,6- strains which results from differential expression of the Q7 and Q9 genes.

Animals↗
PubMed1990

Therapeutic drug monitoring. Practical considerations for primary care physicians.

Primary care physicians who understand the complexities of drug dosing may be able to provide their patients with more effective pharmacologic therapy. Standard or empirical methods of dosing are appropriate for most agents. The evolution of pharmacokinetics and clinically useful drug assays has led to pharmacokinetic dosing, a more sophisticated and exact method of dosing certain agents.

Blood Specimen Collection↗
PubMed1990

Hypothalamic adrenoceptors concerned with control of temperature, elicited by chemical stimulation.

Norepinephrine (NE) and its blockers (alpha-1, alpha-2, beta-1 and beta-2) were micro-injected into the anterior hypothalamus of male albino rats and the effects of these injections on rectal temperature were recorded. The results indicated that the thermoregulatory effects of NE were dependent on ambient temperature. The present study further demonstrated the specific involvement of beta-2 receptors present in the anterior hypothalamus concerned with thermoregulation.

Animals↗
PubMed1987

Interleukin 2 mediates an alteration in the T200 antigen expressed on activated B lymphocytes.

We have examined the effect of exogenous IL 2 on cell surface antigen expression in LPS/dextran sulfate-activated murine B cells with the use of a panel of fluorescein-conjugated lectins. Elevated binding of the lectins PNA and SBA to activated B cells was found to be mediated by IL 2-containing supernatants from stimulated EL4 cells as well as by recombinant IL 2. These lectins have specificity for terminal beta-(1-3)-N-acetylgalactosaminyl residues; thus, the quantity or accessibility of these moieties is mediated by IL 2 in activated B lymphocytes. PNA binding in all strains tested, regardless of MHC or background genes, was found to be elevated fivefold to 15-fold by exogenous IL 2. To observe this effect, IL 2 must be added during the first 24 hr of culture. Based on anti-Thy-1 + complement depletion studies, T cells were not required, suggesting a direct effect of IL 2 on B cells. The glycoprotein responsible for this elevated binding of PNA has an Mr of approximately 220K and by immunodepletion was shown to belong to the T200 (Ly-5) family of cell surface antigens. These data demonstrate that exogenous IL 2 can mediate alterations in T200 expression on activated B cells that may be related to IL 2-driven modulation of B cell proliferation and/or differentiation.

Animals↗
PubMed1984

Development of the skin prick test for allergen assay.

The allergen skin prick test has been optimised for allergen assay for both D. pteronyssinus and grass pollen extracts. The use of an iterative algorithm to select the linear portion of the transformed dose response curve gave an assay that was stable to changes both in the composition of the panels of atopic subjects and in the time intervals between challenge and response measurement. The coefficient of variation of the assay was 18%. The overall robustness of the assay was shown by an isothermal stability trial in which glycerinated D. pteronyssinus remained comparable with a freeze-dried reference preparation at 5 and 20 degrees C for 3 years. A comparison was also made between the first International Reference Preparation to D. pteronyssinus and 'in house' reference preparations. The skin prick test is thus a valuable bioassay for allergen measurement and can provide a reference assay for the calibration of alternative in vitro assays.

Allergens↗
PubMedDate not supplied

Use of evidence in the process of practice change in a clinical team: a study-forming part of the Autocontrol Project.

The Autocontrol Project is concerned with the accessing, processing and communication of high quality information so that a clinical team can make and implement decisions for practice change, and then evaluate if improvement has been achieved. High quality information is used as evidence for change. In this study, we have evaluated how evidence is used by a clinical team to explain an identified problem of inappropriate use of blood gas tests. In an experimental study of the Surgical Intensive Care Unit, video recordings of team meetings of nurses and doctors were undertaken, structured according to a problem-based format. Evidence of current practice patterns derived from the hospital information system, as well as the results of a questionnaire to the unit's staff about knowledge and use of blood gas measurements, were supplied to the participants beforehand. At the second meeting, the output of the first meetings and a summarised analysis of pertinent literature were made available. This second meeting was required to finalise the list of causes of inappropriate blood gas use and propose pragmatic strategies for practice change. The video data of the meetings were coded to analyse the use of evidence, the categories of causes, issues and solutions proposed, and the quality of team interaction. The results indicate that in order to achieve consensus, the team used different types of evidence, including objective evidence of practice patterns, personal experience about direct and indirect organisational influences, and literature-based research evidence of best practice. Furthermore, group dynamics were favoured by the problem-based meeting structure, and a high level of cognitive critiquing between team members was observed. This research suggests that a combination of approaches involving identification of both operational factors (e.g. appropriate access to different types of evidence and meeting structure) and cognitive and behavioural approaches (e.g. ensuring expression of different viewpoints) is needed to support strategic decision-making for practice change in a clinical unit. This combined approach should favourably influence the provision of an effective and efficient evidence support environment for the clinical team.

Blood Gas Analysis↗
PubMedDate not supplied

Risks of intra-abdominal nonshunt surgery in cirrhotics.

We have reviewed the risks of various nonshunt intra-abdominal operations in cirrhotic patients. Most of these studies are retrospective reviews with limitations. Among various risk stratifications in cirrhosis, Child-Pugh classification is sufficiently informative. Elective surgery can be done safely in patients with Child's A or B class. Operations in Child's C patients and emergent surgery carry formidably high mortality. Limiting the extent of surgery, controlling ascites, correcting coagulation abnormality and malnutrition and aggressively treating infection, might reduce mortality. Laparoscopic cholecystectomy and endoscopic sphincterotomy in cirrhotics seem to be promising in reducing mortality and morbidity.

Digestive System Surgical Procedures↗
PubMedDate not supplied

Symptomatic small non-obstructing lower ureteric calculi: comparison of ureteroscopy and extra corporeal shock wave lithotripsy.

OBJECTIVE: To compare the success, efficacy and complications of ureteroscopy (URS) and extra corporeal shock wave lithotripsy (ESWL) for the treatment of symptomatic small non obstructing lower ureteric calculi. SUBJECTS AND METHODS: This prospective non-randomised study was conducted simultaneously at two urological referral centres, included 280 patients with symptomatic small (4-10 mm) lower ureteric calculi (situated below the sacroiliac joint), with good renal function on intravenous urography. Patients were offered both the treatment options. One hundred and sixty patients chose ureteroscopy, whereas 120 patients were treated by ESWL. Standard techniques of ureteroscopy and ESWL were employed. Patients were followed-up to assess the success rates and complications of the two procedures. RESULTS: Ureteroscopy achieved complete stone clearance in one session in 95% of patients. In six patients ureteroscopy had failed initially and was later accomplished in second session improving the success rate to 98.7%. Two patients had a proximal migration of calculus that needed ESWL. Of the 120 patients treated by ESWL, 90% achieved stone free status at three months. Ureteroscopy was needed for twelve patients (10%) where ESWL failed to achieve stone clearance. There were no significant ESWL related complications. ESWL was administered on outpatient basis, while patients needed hospitalisation and anaesthesia for ureteroscopy. CONCLUSION: ESWL can be the primary mode of treatment for symptomatic small non-obstructing lower ureteric calculi as it is minimally invasive and safe. Ureteroscopy can be offered to patients who demand immediate relief or when ESWL fails.

Adolescent↗
PubMedDate not supplied

Effect of tonicity on glucose absorption and histomorphology of rat intestinal mucosa.

Perfusion of the gut lumen with 2 ml of isotonic solutions showed uniform absorption of glucose and water over the four 15-minutes study periods, the absorption being maximum in jejunum and least in colon. With hypertonic solutions the glucose absorption decrease was related to the increasing osmolarity and duration of exposure to the solution as well as the nature of the substance used. Histological changes reflecting impaired functions were localised to the tips of the villi and were observed on exposure to hypertonic solution for 45 minutes or more.

Animals↗