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Biomedical subjects

S Chawla

Publications and source records attributed to S Chawla.

At least 73 records · Page 4Linked to original sources
PubMed1978

Congenital duodenal stenosis. The duodenal cervix sign.

A case of congenital duodenal stenosis is reported complicated by recurrent pancreatitis. The diagnosis was not initially entertained because of the pancreatitis. The radiographic appearance on gastrointestinal series was unusual for pancreatitis. The finding of an anomalous celiac axis on arteriography suggested the possibility of other congenital anomalies. The diagnosis of congenital duodenal stenosis was confirmed at laparotomy. The obstruction was relieved with a duodenojejunostomy. Two year follow-up reveals the patient to be asymptomatic without recurrence of pancreatitis. This is the first endoscopic report of this lesion and the presence of the duodenal cervix sign should suggest the diagnosis of congenital duodenal stenosis.

Adult↗
PubMedDate not supplied

Aldehyde dehydrogenase in Drosophila: developmental and functional aspects.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities were determined in adult flies from several Drosophila species endowed with widely different tolerance to ethanol (ETOH). Plotting ALDH against ADH activities resulted in a high correlation coefficient (r = 0.966). This finding was confirmed in developmental studies. From early larval stage up to late adult life, ADH and ALDH activities demonstrated almost parallel profiles. In the highly ETOH tolerant species D. melanogaster (D.m.), ADH and ALDH profiles were U-shaped: high activities in larvae, low activities in pupae and high activities in adults. In D. simulans (D.s.), a species less tolerant to ETOH, the profiles were L-shaped: high activities in larvae but low activities in both pupae and adults. Interestingly, similar activities (ADH and ALDH) were observed in the larvae of both species. Subcellular distribution studies of larval ALDH in both species revealed that the total ALDH activity is largely contributed by a mitochondrial high affinity enzyme. ALDH activity, clearly distinguishable from aldehyde oxidase (ALDOX), was visualized through analytical isoelectric focusing of the subcellular fractions. The estimated pIs for D.m. and D.s. were 4.9 and 5.2 respectively, thus different from those of ADH. The key biological role initially attributed to Drosophila ALDH is further supported by the present data. In addition the Drosophila developmental model opens new avenues for research on the study of genetic regulation of ADH and ALDH expression.

Alcohol Dehydrogenase↗
PubMedDate not supplied

Mechanisms controlling gene expression by nuclear calcium signals.

Nuclear calcium is an important regulator of gene expression following membrane depolarisation of electrically excitable cells. Here we describe nuclear calcium transients in hippocampal neurons following activation of calcium influx through L-type voltage-sensitive calcium channels and N-methyl-D-aspartate (NMDA) receptors, as well as following calcium release from intracellular caffeine-sensitive stores. Increases in nuclear calcium activate gene transcription by a mechanism that is distinct from gene regulation by cytoplasmic calcium signals and involves the cAMP response element (CRE) and the CRE binding protein, CREB. The nuclear calcium/calmodulin dependent (CaM) protein kinase IV, which is expressed in cultured hippocampal neurons and in the mouse pituitary cell line AtT20, may function as a mediator of nuclear calcium-induced transcription.

Animals↗
PubMedDate not supplied

Social support as a moderator of cardiovascular reactivity in women: a test of the direct effects and buffering hypotheses.

This study examines the possibility that social support operates as a moderator of cardiovascular reactivity in women. Two models by which social support may operate were examined: the direct effects and buffering models. Twenty-six subjects were exposed to four conditions while playing a video game: two levels of stress (low, high) and two levels of social support (alone, together). Blood pressure and heart rate were monitored continuously. Ratings of stress were obtained for each condition. Results indicated that the support manipulation produced significant main effects for diastolic blood pressure and stress ratings, with lower diastolic blood pressure and ratings observed in the "together" condition, and that the interaction between support and stress produced lower reactivity for the cardiovascular measures in the high stress (but not the low stress) condition. No interaction was found for the stress ratings. We conclude that the results provide support for both the buffering and direct effects models. Implications concerning the (within-subjects) design of the study and the stress ratings are discussed.

Adolescent↗
PubMedDate not supplied

Aberrant oncogene expression in uncultured human sarcoma and melanoma.

Protooncogenes have the ability to induce and/or maintain the transformed state when they are overly expressed or altered by mutation or gene rearrangement. To study the possible involvement of these cellular oncogenes in the neoplastic transformation, we have analyzed their expression in 44 fresh samples obtained from primary, recurrent, or metastatic tumors from patients with a variety of sarcomas and a melanoma. Our analysis was carried out by the northern blot technique using poly (A)+ RNA hybridized with human cellular DNA probes. A normal 2.3-kb c-myc transcript was observed almost universally at various levels. A normal c-k-ras transcript of 5.2-kb was detected at a low level in most of the samples. In three samples we detected aberrant c-k-ras transcripts of 7.0 and 8.5-kb, while in two other samples we found an aberrant lower-molecular-weight transcript of 1.4-kb. N-myc was expressed in only three samples, and in all instances, the transcripts were aberrant (more than 10-kb). A normal 3.7-kb c-sis transcript was expressed at a low level in most of the sarcomas and the melanoma but was uniquely overexpressed in giant cell tumors of bone. C-fos (2.2-kb) was expressed at a low level in almost half of the samples; c-myb was never expressed. We conclude that c-k-ras, n-myc, c-sis, and c-myc are aberrantly or overexpressed in sarcoma/melanoma, and their activation may play a role in the transforming events leading to development and/or progression of these tumors.

Gene Expression Regulation↗