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Biomedical subjects

T Singh

Publications and source records attributed to T Singh.

At least 109 records · Page 6Linked to original sources

Unusual complications of pancreatitis.

The computed tomography (CT) appearances of varying grades of severity of acute pancreatitis, and its complications, have been described. Bodywall ecchymosis in the periumbilical region (Cullen's sign) and loins (Grey Turner's sign), though rare, are frequently mentioned in the clinical literature. Massive, exclusively retroperitoneal, involvement is also exceedingly rare. Computed tomography depiction of these signs is sparsely documented. The CT documentation, with clinicosurgical correlation, of two cases of severe acute pancreatitis with these unusual complications, is presented.

Acute Disease↗

Clonal analysis of erythropoietin stimulated J2E cells reveals asynchrony during terminal differentiation.

J2E erythroid cells proliferate and differentiate in response to erythropoietin (epo), the red blood cell specific hormone. Using methylcellulose colony assays and suspension cultures we have demonstrated that nearly all the cells stimulated by epo synthesized haemoglobin. To achieve maximum production of haemoglobin J2E cells had to be treated with epo for only 6 h; hormone added subsequently did not enhance haemoglobin synthesis. Although virtually all viable J2E cells produced haemoglobin, the cells matured morphologically at different rates. Thus, upon exposure to epo J2E cells become committed to erythroid terminal differentiation but proceed in an asynchronous manner.

Cell Division↗

Marrow histomorphology and clinical staging of chronic lymphocytic leukemia--a rare disease in India: experience with 26 cases.

Chronic Lymphocytic Leukemia is a relatively uncommon hemopoietic malignancy in the Indian subcontinent. We have made an attempt to correlate the morphology of the marrow with staging and clinical course of the disease in 26 cases. Four out of 6 cases in Stage A showed a nodular/interstitial marrow pattern, while 18 out of 20 cases of stage B and C demonstrated a mixed/diffuse involvement of marrow. Cases showing a nodular/interstitial pattern had a relatively benign clinical course even without chemotherapy, while patients with diffuse/mixed marrow pattern required chemotherapy. Trephine histological pattern was found to be a good prognosticator and was useful in segregating cases requiring chemotherapy from those which do not.

Aged↗

Attitudes of medical students towards Objective Structured Clinical Examination (OSCE) in pediatrics.

A standardized Likert type scale containing 10 items was administered to 40 Fourth year medical students to assess their attitudes towards Objective Structured Clinical Examination (OSCE). The overall attitudes were favorable. However, on certain aspects, a near neutral attitude was observed. Remedial changes in the teaching methodology have been undertaken to mould the attitudes favorably as well as to make pediatric teaching more effective.

Attitude↗

Experiences with objective structured clinical examination (OSCE) as a tool for formative evaluation in pediatrics.

Mean scores obtained at objective structured clinical examination (OSCE) and clinical case (CC), by 4 groups of 15 students each were compared. The range of dispersion was more with OSCE as compared to CC. There was no correlation between the scores obtained at OSCE and CC. It is suggested that OSCE can be employed for evaluation of specific clinical skills; however, for comprehensive evaluation, a combination of OSCE and CC should be used.

Clinical Competence↗

Molecular pathology of Alzheimer neurofibrillary degeneration.

The most characteristic brain lesion of Alzheimer disease is the accumulation of paired helical filaments (PHF) in the affected neurons. Based on solubility in detergents there are two general populations of PHF, the readily soluble (PHF I) and the sparingly soluble (PHF II) types. The major polypeptides of PHF are the microtubule associated protein tau. Tau in PHF is present in abnormally phosphorylated forms. In addition to the PHF, the abnormal tau is also present in unpolymerized form in the AD brain. Small amounts of ubiquitin (%) are associated with PHF II but neither with PHF I nor with the unpolymerized abnormally phosphorylated tau in AD brain. Furthermore, the pretangle neurons can readily be immunolabeled for abnormally phosphorylated tau but not for ubiquitin. The level of tau in neocortex is several-fold higher than in AD aged control cases, but this increase is in the form of the abnormally phosphorylated protein. The microtubule associated proteins from AD brain do not promote the assembly of microtubules in vitro, whereas the in vitro dephosphorylated PHF polypeptides stimulate the binding of GTP to the exchangeable site of tubulin and the assembly of microtubules. In vitro the phosphate groups in PHF are less accessible than those of tau to alkaline phosphatase. It is suggested that a defect in the protein phosphorylation/dephosphorylation system leads to hyperphosphory-lation of tau. The altered tau contributes to a microtubule assembly defect and consequently compromises the axoplasmic flow and leads to neuronal degeneration.

Alzheimer Disease↗

Attitudes of medical students towards IAP Pediatric Quiz.

Attitudes of medical students towards IAP Pediatrics Quiz were assessed, using a 5 point pre-tested, standardized Likert type scale, developed in our own department. Students had a favorable attitude towards the Quiz and felt that it helps them in the study of Pediatrics, but they are not able to devote sufficient time for preparations because of their preoccupation with other major subjects. The attitudes demonstrated a decline towards unfavorableness when comparison was made between the scores of third year and final year medical students. The difference was statistically significant (p < 0.05). It is suggested that the timing of the Quiz should be changed, so that it doesn't coincide with final professional examinations. This will make it more popular besides generating interest of medical students in Pediatric. Giving more weightage to Pediatrics in university examinations is also re-emphasized as a means of making students more interested in pediatrics.

Attitude↗

Evaluation of sterically stabilized liposomes as a vehicle for targeting technetium-99m labelled radiopharmaceuticals.

Sterically stabilized neutral liposomes (multilamellar vesicles) were prepared by sonicating phosphatidylcholine and cholesterol (molar ratio 4:1) film in phosphate buffered saline (50 mM, pH 7.4) containing 4% Tween 20. Tc-99m-GHA was incorporated in these liposomes by treating 0.5 ml of the suspension with lyophilized GHA kit (5 mg GHA and 250 micrograms SnCl2 x 2 H2O) followed by addition of 1 ml 99mTcO4- (1-3 mCi). The labelling yield was 60-70%. Tween 20 has provided significant stability of the radiolabel as compared to that without its addition, when radiolabelled liposomes were incubated in serum up to 24 h. With respect to Tc-99m-GHA alone, radiolabelled liposomes exhibited 4- to 6-fold greater radioactivity in the blood of rabbits (15 min-24 h). Comparison of biodistribution data of radiolabelled liposomes and Tc-99m-GHA in mice demonstrated a 10- to 12-fold greater hepatic accumulation of radiolabelled liposomes with respect to that of Tc-99m-GHA throughout the period of study (15 min-24 h), though their concentration in the kidneys was comparable.

Animals↗

Eosinophilia-myalgia syndrome in patients ingesting a single source of L-tryptophan.

OBJECTIVE: To estimate the attack rate for eosinophilia-myalgia syndrome and to identify potential risk factors for illness among patients attending a New York City medical clinic, who purchased L-tryptophan containing products produced exclusively by Showa Denko K.K. METHODS: A case-control design was used. Cases and controls purchased L-tryptophan containing products at the medical clinic from July 1, 1989--December 1, 1989. All case-patients identified with illness onset during the study period were included. Controls were selected by a systematic sample of the 683 purchasers of L-tryptophan attending the same clinic. RESULTS: Twelve (2.2%) of an estimated 553 L-tryptophan users were case-patients. Multivariate analysis suggested that lot 2 use (adjusted odds ratio [OR] = 35.9), concomitant use of chromium (adjusted OR = 12.3), and concomitant use of pyridoxine (adjusted OR = 5.8) were associated with the development of illness. Chemical analysis of tablets corresponding to the 3 Showa Denko K.K. lots ingested by study participants showed that lot 2 had the highest concentration of ethylidenebis (L-tryptophan), a proposed causative agent or marker for a causative agent in the eosinophilia-myalgia syndrome. CONCLUSIONS: Information from our study of persons exposed to implicated L-tryptophan supports the role for a contaminant as the causative agent in the eosinophilia-myalgia syndrome and identifies possible cofactors that deserve further study.

Case-Control Studies↗

Trends in survival for children reported with maternally transmitted acquired immunodeficiency syndrome in New York City, 1982 to 1989.

To better understand the natural history of severe pediatric human immunodeficiency virus infection, reported cases of perinatally acquired pediatric acquired immunodeficiency syndrome (AIDS) in New York City were examined for differences in survival and age at diagnosis before and after implementation of an expanded case definition in 1987. One hundred ninety-six children reported through August, 1987, and 333 children reported between September, 1987, and February, 1990, and diagnosed through 1989 were compared. Significant differences were not found in survival by either gender or race/ethnicity although Hispanics were slightly more likely to be diagnosed with Pneumocystis carinii pneumonia (PCP) and blacks with lymphocytic interstitial pneumonitis (LIP). The most striking differences were noted regardless of race between children whose earliest AIDS-specific diagnosis was PCP and those whose earliest diagnosis was LIP. In the group reported through August, 1987, median survival from birth was 10 months with PCP vs. 54 months with LIP, median age at diagnosis 5 months vs. 20 months, and median survival after diagnosis 2 months vs. 22 months, respectively. Twelve-month survival for PCP improved in the two time periods examined, but survival with LIP did not. After implementation of the 1987 case definition, bacterial infections replaced LIP as the second most common diagnosis. This study provides data on children diagnosed and reported with AIDS. Ongoing prospective studies of children who have a full spectrum of human immunodeficiency virus infection with and without reportable AIDS wil further elucidate survival in children infected with human immunodeficiency virus.

Acquired Immunodeficiency Syndrome↗

Cardiovascular effects of omega-conopeptides in conscious rats: mechanisms of action.

We examined the effects of omega-conopeptides, a novel class of neuronal voltage-gated calcium channel antagonists, on hemodynamic responses in rats. Intravenous (i.v.) injections of SNX-111 (omega-conopeptide MVIIA) dose-dependently decreased arterial blood pressure (BP) in conscious rats. Intracerebroventricular (i.c.v.) SNX-111 injections (580 pmol) tended to increase BP and, after an initial decrease, to increase heart rate (HR). The dose-response curve for SNX-111 administered i.v. in conscious rats was biphasic. Beginning at subdepressor doses, SNX-111 caused a long-lasting blockade of pressor responses elicited by sympathetic nerve stimulation in pithed animals but did not prevent increases in BP evoked by exogenously administered norepinephrine (NE). Pretreatment of rats with histamine antagonists partially blocked the hypotensive effects of the higher (870 and 2,900 nmol/kg) doses of SNX-111. Substitution of alanine for arginine at position 10 ([Ala10]-MVIIA) markedly attenuated the histamine-mediated component of the vasodepressor response. Together, these findings indicate that SNX-111 administered i.v. decreases systemic BP by a combination of blockade of sympathetic neurotransmission and mast cell degranulation; the latter function appears to be dependent on the arginine residue in position 10 of the amino acid sequence of SNX-111.

Amino Acid Sequence↗