Biomedical subjects
Publications and source records attributed to P Mehta.
An infant born in a compound presentation had ischemic forearm necrosis requiring amputation. Bilateral renal vein thrombosis predating labor and delivery was also diagnosed. The possibility of congenital ischemic necrosis in an extremity should not affect the obstetrical management of compound presentation, but if this complication occurs a search for an underlying coagulopathy is important.
Two widely used B16 melanoma cell lines of low and high lung colonizing potential (B16-F1 and B16-F10) were compared in their ability to induce platelet aggregation. The results of these experiments showed a reproducible difference in platelet aggregating activity of these two cell lines which directly correlated with their lung colonizing potentials. However, when clones were derived from these heterogeneous cell lines and tested for experimental metastatic potential, platelet aggregating ability and Met-72 expression, no correlation could be attached to the platelet aggregating activity of the clones. Results of these experiments provide direct evidence that platelet aggregation is not an accurate index of experimental metastatic potential of tumor cell clones, nor is it an essential trait of all metastatic cells. The ability of tumor cells to induce platelet aggregation is examined and discussed in the context of cellular heterogeneity.
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The mechanism of heparin-induced platelet aggregation potentiation is much debated. We examined the effects of heparin on platelet aggregation induced by cyclic endoperoxide analog u46, 619. Heparin enhanced platelet aggregation in a dose-related fashion. Potentiation of platelet aggregation was also found to be related to the incubation time of heparin and platelet rich plasma. Porcine intestinal heparin and bovine lung heparin exhibited similar patterns. To test the hypothesis of increased platelet thromboxane A2 production under the influence of heparin, we measured U46,619-induced thromboxane A2 generation. Heparin was found not to affect platelet thromboxane A2 generation over a wide range of concentrations. The platelet aggregation potentiating actions of heparin are thus unrelated to thromboxane A2 pathway.
Protein protein interactions play a significant role in maintaining the structural and functional integrity of the cell. We used multiple antigen peptides (MAPs) to analyze such interactions within the Ro (or SSA) ribonucleoprotein complex. Our data showed that 60 kD Ro and La colocalize in the nucleus of the cell. Previous data have indicated that 60 kD Ro and La co-exist via interactions with the hYRNAs. We were interested to see whether 60 kD Ro and La interact with each other through protein protein interactions. MAPs were produced with sequences derived from the autoepitopes of 60 kD Ro. When used in agarose immunodiffusion certain MAPs formed precipitin lines specifically with Ro and La antigens. Used in affinity chromatography the Ro MAPs purified the Ro ribonucleoprotein particle from lymphocyte extract. Solid phase immunoassay and surface plasmon resonance (SPR) confirmed the observations obtained with agarose diffusion. Using SPR, kinetic analyses gave an apparent affinity constant of about 1 x 10(7) M(-1) for Ro-MAP-60 kD Ro interactions. The autoantigens Ro and La are specific targets in autoimmune diseases, particularly systemic lupus erythematosus (SLE) and Sjögren's syndrome, and are known to exist together as a complex with hYRNAs. The present data indicate that there are protein-protein interactions between Ro and La.
Excess nitric oxide (NO) generation in the presence of superoxide anion (O2-) leads to the formation of peroxynitrite which may result in lung injury. Oxidant-mediated lung injury has a critical role in pulmonary diseases. We therefore determined whether peroxynitrite causes lung fluid accumulation, lipid peroxidation, and formation of nitrotyrosine using an isolated perfused rat lung model. The lung weight gain during bolus peroxynitrite infusion increased in a dose-dependent manner over a range of 3 to 30 mumole. Concomitantly, bronchoalveolar lavage Ficoll also increased, indicative of increased endothelial permeability. Peroxynitrite increased the production of thiobarbituric acid reactive substances, an index of lipid peroxidation. Furthermore, nitrotyrosine levels in lung tissue rose with increased concentration of peroxynitrite, as determined by Western blot using antinitrotyrosine antibodies. These results suggest that peroxynitrite, formed from NO and O2-, leads to increased pulmonary fluid accumulation, possibly through lipid peroxidation and/or nitration of cell membrane proteins.
The UK is a multi-ethnic, multicultural society with over 300 languages spoken in the capital (London) alone. This short report explores the implications of a diverse population on health and access to genetic services. It considers genetic, cultural and linguistic differences, and provides evidence of inequalities in access. Following recent legislation promoting race equality, the report highlights current activities and shortfalls, and proposes recommendations towards achieving greater equity of access within the context of clinical genetics service provision.
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Modification of platelet function and vessel wall prostaglandin synthesis by pharmacologic intervention has attracted considerable attention. We report our observations on the effects of aspirin and dipyridamole alone and their combination on platelet aggregation and vessel wall prostacyclin (PGI2) generation. Although dipyridamole alone had no effects on platelet aggregation, it potentiated the platelet aggregation inhibitory effects of aspirin in vitro in a dose-related fashion. Dipyridamole also enhanced the platelet aggregation inhibitory effect of synthetic PGI2 in vitro. Potentiation of aspirin- and PGI2-induced platelet aggregation inhibition was observed in therapeutic range (5-10 micrograms/ml). In an isolated umbilical vein model dipyridamole stimulated release of PGI2 at much higher concentration (50-100 microgram/ml). Treatment of umbilical vein with aspirin (180 micrograms/ml) for 10 min blocked the spontaneous release of PGI2. In aspirin-treated umbilical vein segments dipyridamole treatment did not cause PGI2 release as in the untreated segments. These experiments suggest that although dipyridamole enhances both aspirin- and PGI2-induced platelet aggregation inhibition in clinically achieved concentrations, much higher levels are necessary for PGI2 release from intact human vessels. Furthermore, aspirin treatment of human vessels may prevent release of PGI2 in response to dipyridamole by blocking cyclooxygenase enzyme.
Three models of the relations of coping efficacy, coping, and psychological problems of children of divorce were investigated. A structural equation model using cross-sectional data of 356 nine- to twelve-year-old children of divorce yielded results that supported coping efficacy as a mediator of the relations between both active coping and avoiding coping and psychological problems. In a prospective longitudinal model with a subsample of 162 of these children, support was found for Time 2 coping efficacy as a mediator of the relations between Time 1 active coping and Time 2 internalizing of problems. Individual growth curve models over four waves also found support for coping efficacy as a mediator of the relations between active coping and psychological problems. No support was found for alternative models of coping as a mediator of the relations between efficacy and symptoms or for coping efficacy as a moderator of the relations between coping and symptoms.
A portion of Alzheimer's disease (AD) patients have elevated serum levels of the acute phase reactant alpha 1-antichymotrypsin (A1ACT) compared to age-matched controls. We measured serum levels of A1ACT in AD patients, age-matched controls, Down's syndrome patients, and nondemented first-degree relatives of AD patients. Significantly elevated levels of A1ACT were found in both AD patients and first-degree-relatives. In AD patients, serum A1ACT concentrations decreased with increasing severity of cognitive impairment. These results may suggest that inflammatory phenomena may be an early component of AD pathophysiology.
In vivo circulating platelet aggregates (CPA) were evaluated in 18 patients aged 6 to 17 years with sickle cell disease and in 11 age and sex matched normal subjects. Twelve patients with sickle cell disease were in steady state and 6 had vaso-occlusive crises. CPA in patients in steady state were similar to those in normal subjects (mean 6 +/- 1% compared to 5 +/- 2%, respectively), whereas patients with vaso-occlusive crisis in acute state had significantly higher CPA (mean 39 +/- 8%) than patients in steady state or normal control individuals (both p less than 0.001). CPA decreased in patients with vaso-occlusive crisis (mean 11 +/- 4%) on the tenth day, in association with clinical improvement. This study suggests that in vivo platelet aggregate formation activity, although normal in sickle cell disease patients in steady state, is significantly increased in patients with vaso-occlusive crises.
Munchausen's syndrome and Munchausen's syndrome by proxy (MSBP) can cause many conditions, including bleeding problems, seizures, failure to thrive and others. We report here an unusual case in which a mother presented to the hospital for her hemophiliac son's failure to thrive, subsequently for her own self-inflected mutilating wounds, and finally for self-induced simulation of her son's hemophiliac bleeding and arthritic complications.
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Geriatric population forms a significant proportion of our total population. Hence, various problems affecting the overall health of the elderly need special consideration. In this context, studies were undertaken to assess the socio-demographic factors, diet and health profile of 320 elderly men and women of all the three income groups of Urban Baroda. Data on socio-demographic factors was collected using an open ended questionnaire. Nutritional status was assessed using anthropometric measurements of height, weight, mid upper arm circumference (MUAC) and body mass index (BMI). Information on dietary profile was collected by 24 hour dietary recall method. Fasting practices were also studied. Socio-demographic data of geriatric men of high, middle and low income groups revealed that majority of the subjects were married. A greater percentage of high income group (HIG) men had nuclear family whereas majority of low income groups (LIG) elderly men resided in a joint family. Socio-demographic profile of elderly women of all the 3 income groups revealed that most of the subjects were Hindus. The percentage of widowhood, illiteracy and joint family system were higher in LIG as compared to the elderly women in middle and high income groups (MIG and HIG). Nutrient intake data of elderly men of all the income groups revealed lower consumption of energy, protein, iron and beta-carotene as compared to the RDA whereas fats and vitamin C intakes were higher as compared to the RDA (p < 0.05). The mean nutrient intake, by the LIG elderly women, in terms of energy, protein, iron, calcium, beta-carotene and vitamin C were significantly (p < 0.05) lower than the RDA as well as when compared to the elderly women of MIG and HIG. Mean anthropometric measurements of weight and BMI were higher in elderly HIG and MIG men as compared to the elderly men from LIG. Significant difference was found in all the anthropometric measurements of elderly women of LIG as compared to HIG and MIG. Morbidity profile showed a striking rise in problems of oral cavity, cardio vascular disease, neurological problems and problems of gastro intestinal tract with advancing age in both elderly men and women. The study reveals striking differences in diet, health and disease profile with advancing age.
BACKGROUND AND AIM: Bacteriological studies are necessary to confirm the diagnosis of tuberculous lymphadenitis, as cytological appearances mimic other granulomatous lesions. The objective was to assess the diagnostic role of culture of fine needle aspiration done on clinically suspected cases of tuberculous lymphadenitis and to determine the prevalence of drug resistance in M. tuberculosis isolates. SETTING AND DESIGN: A prospective, double-blind study over a period of one year in a tertiary care hospital. MATERIAL AND METHODS: Fine needle aspiration cytology and culture were done on 250 patients with clinical suspicion of tuberculous lymphadenitis. STATISTICAL ANALYSIS: Data was statistically analysed using chi square test. Sensitivity, specificity, positive predictive and negative predictive values and likelihood ratio were also calculated. RESULT: Of the 161 cytologically or microbiologically proven cases of tuberculous lymphadenitis, cytological changes consistent with tuberculosis were observed in 133 patients, out of which mycobacteria were isolated in 102 aspirates. Mycobacteria were also isolated from 28 aspirates cytologically missed as tuberculous lymphadenitis. Of the 130-mycobacterial isolates, 5 were non-tuberculous mycobacteria. Culture positivity was significantly higher (P<0.001) than smear positivity. Drug susceptibility studies showed resistance to one or more drugs in 61% of isolated strains with maximum resistance to isoniazid (16% primary and 48% secondary) and minimum to ethambutol (4% primary and 12% secondary). CONCLUSION: Culture for mycobacteria should be carried out on all aspirates from patients suspected with tuberculous lymphadenitis.