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Biomedical subjects

S Kannan

Publications and source records attributed to S Kannan.

At least 19 recordsLinked to original sources
PubMed2002

(Dibenzyl sulfoxide-kappa O)bis(1,3-diphenylpropane-1,3-dionato-kappa(2)O,O')dioxouranium(VI).

In the title compound, [UO(2)(C(15)H(11)O(2))(2)(C(14)H(14)OS)], the U(VI) atom is coordinated by seven O atoms in a distorted pentagonal-bipyramidal geometry. Both diphenylpropane-1,3-dionate systems are nearly planar. The sulfoxide moiety is in a distorted tetrahedral geometry, while its two aromatic rings are nearly orthogonal to one another. The crystal packing is stabilized by two bifurcated hydrogen-bonding interactions involving both uranyl O atoms.

Journal Article↗
PubMed2002

Amplification of extracellular nucleotide-induced leukocyte(s) degranulation by contingent autocrine and paracrine mode of leukotriene-mediated chemokine receptor activation.

Extracellular nucleotide-induced stimulation and activation of peripheral blood leukocytes and subsequent degranulation play a critical role in immediate-type hypersensitivity reaction and other inflammatory diseases. The extracellular nucleotides stimulate a P2Y receptor(s) on human PMN with the pharmacological profile similar to that of the P2Y2 receptor. Upon activation of P2Y2, arachidonic acid, formed from the membrane bound lipids by phospholipase A2, which subsequently metabolized by 5-lipoxygenase to form the leukotrienes. Of the several leukotrienes generated, LTB(4) is a potent pro-inflammatory chemokine. Upon its release LTB(4) binds to the PMN in a paracrine manner and also other leukocytes such as monocytes at the site of vascular injury, leading to an accelerated rate of degranulation. It is known that LTA(4) formed in the 5-lipoxygenase pathway in PMN could be released from PMN by receptor-mediated transport. Upon its release, the monocytes, erythrocytes, platelet, endothelial or smooth muscle cells can take up LTA(4). The endogenous LTA(4) hydrolase form the LTB(4) from LTA(4) in erythrocytes, platelet, endothelial or smooth muscle cells. As in PMN, LTB(4) is released from these cells via receptor-mediated transport to the extracellular milieu. Thus, released LTB(4) most likely acts as potentially accelerating factor in PMN and MN degranulation through its receptor-specific binding. It is not known whether any LTB(4) receptor exists in cytoplasm in any given cell type and also, the existence of any other signaling cascade for the extracellular nucleotide-induced leukocyte degranulation. Thus, it is convincing that the extracellular nucleotides released from the activated platelets and other damaged cell types exacerbate the inflammatory response by leukotriene generation. In turn the leukotriene will act in both autocrine and paracrine manner to amplify the degranulation processes in leukocytes invoked by extracellular nucleotides.

Animals↗
PubMed2002

Role of protease-activated receptors in neutrophil degranulation.

Inflammation is a process culminated by cellular components and soluble mediators act in concert to evolve a sustainable process to impart distress in vascularized tissue. The role of thrombin receptors in neutrophil degranulation is not fully understood. Thrombin-mediated signaling has been shown to occur at least in part by a family of G protein-coupled protease-activated receptors (PARs). Protease-activated receptors-1 (PAR1) is the prototype for understanding on the fundamental signaling mechanism and related characterization. The inference of thrombin receptors and various synthetic ligand formulations on neutrophil degranulation ascertained an enormous disparity in the response by human donors. Based on the previous reports and supposition in perpetuity, it is hypothesized that thrombin through its receptor, and its subtypes, may very improbably have any functional role in PMN degranulation.

Animals↗
PubMed2002

Infrequent loss of heterozygosity of the major tumour suppressor genes in Indian oral cancers.

The loss of heterozygosity (LOH) in tumour suppressor gene loci such as p53, retinoblastoma (rb) and adenomatous polyposis coli (apc) were analyzed in oral cancer tissues with matched controls by employing polymerase chain reaction based/restriction fragment length polymorphism (PCR-RFLP), variable number of tandem repeats (PCR-VNTR) analysis and microsatellite assay. The PCR-RFLP analysis showed an infrequent LOH in rb (17%), p53 (11%) and apc (10%) loci in these cases. The microsatellite assay also revealed only a low frequency of LOH in the microsatellite markers such as TP53 (25%), D5S505 (10%) and D3S1067 (0%) in the same samples. In contrast to the present study, similar studies from Western countries have reported a high frequency of LOH in p53, rb and apc genes in oral cancer tissues. The present preliminary study indicates that the gene aberration by LOH may be an insignificant mechanism in Indian oral cancers with respect to the tumour suppressor genes examined.

Adult↗
PubMed2002

E-NTPase/NTPDase: potential role as a regulatory element in inflammation.

Inflammation is a process culminated by cellular components and soluble mediators act in concert to evolve a sustainable process to impart distress in vascularized tissue. Among the contributors, extracellular nucleotides are prominent in PMN granule release (degranulation); chemotaxis, enhanced expression of adhesion molecule on the surface of PMN. However, co-stimulatory effectors such as chemokines are required for the extracellular nucleotide-induced maximal effect in inflammation. Enzymes, which degrade the extracellular nucleotide(s), could potentially attenuate or minimize the extracellular nucleotide(s) induced effect by degradation.

Acid Anhydride Hydrolases↗
PubMed2002

Termination of supraventricular tachycardia by propofol.

It is known that propofol can have effects on atrioventricular node conduction. We report a case where administration of propofol was associated with termination of supraventricular tachycardia. Although a similar phenomenon has been reported in children, this is the first such case in an adult.

Aged↗
PubMed2002

Flow-by induced hypoventilation in high spinal cord lesions--report of two cases.

Flow triggering in ventilators is an alternative to pressure triggering. Differences between these two trigger mechanisms may not be clinically significant in most patients. We report two patients with high spinal cord lesions in whom the use of flow triggering was unsuccessful. Severe muscle weakness in these patients made them sensitive to small changes in ventilator trigger characteristics.

Adult↗
PubMed2001

ATF-7, a novel bZIP protein, interacts with the PRL-1 protein-tyrosine phosphatase.

We have identified a novel basic leucine zipper (bZIP) protein, designated ATF-7, that physically interacts with the PRL-1 protein-tyrosine phosphatase (PTPase). PRL-1 is a predominantly nuclear, farnesylated PTPase that has been linked to the control of cellular growth and differentiation. This interaction was initially found using the yeast two-hybrid system. ATF-7 is most closely related to members of the ATF/CREB family of bZIP proteins, with highest homology to ATF-4. ATF-7 homodimers can bind specifically to CRE elements. ATF-7 is expressed in a number of different tissues and is expressed in association with differentiation in the Caco-2 cell model of intestinal differentiation. We have confirmed the PRL-1.ATF-7 interaction and mapped the regions of ATF-7 and PRL-1 important for interaction to ATF-7's bZIP region and PRL-1's phosphatase domain. Finally, we have determined that PRL-1 is able to dephosphorylate ATF-7 in vitro. Further insight into ATF-7's precise cellular roles, transcriptional function, and downstream targets are likely be of importance in understanding the mechanisms underlying the complex processes of maintenance, differentiation, and turnover of epithelial tissues.

Activating Transcription Factors↗
PubMed2001

Regulation of heparin-binding EGF-like growth factor expression in Ha-ras transformed human mammary epithelial cells.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) mRNA and protein expression is induced by EGF in MCF-10A nontransformed and Ha-ras transfected human mammary epithelial cells. The anti-EGF receptor (EGFR) blocking monoclonal antibody (MAb) 225 and the EGFR tyrosine kinase inhibitor PD153035 were able to inhibit the induction of HB-EGF mRNA levels in MCF-10A cells. However, the Ha-ras transformed MCF-10A cells were more refractory to inhibition by these agents and only a combination of the 225 MAb and PD153035 was able to significantly abrogate HB-EGF induction by EGF. The anti-erbB2 MAb L26 which interferes with heterodimer formation was able to block HB-EGF induction in response to EGF in MCF-10A cells and in the Ha-ras transformed cells only when used in combination with either the 225 MAb or PD153035. The MEK inhibitor PD90859 completely blocked EGF induction of HB-EGF mRNA levels in the nontransformed and Ha-ras transformed MCF-10A cells, which indicates that MAPK is involved in the signaling pathway of HB-EGF induction by EGF. An increase in the levels of HB-EGF may, therefore, be an important contributor to oncogenic transformation that is caused by Ha-ras overexpression in mammary epithelial cells. J. Cell. Physiol. 186:233-242, 2001. Published 2001 Wiley-Liss, Inc.

Antibodies, Monoclonal↗
PubMed2001

Chemistry of clitoral gland secretions of the laboratory rat: assessment of behavioural response to identified compounds.

The present investigations were carried out to find out the chemical nature of clitoral gland extracts and their involvement in reproductive and social behaviour. Homogenates of clitoral glands of mature estrous female rats were extracted with n-hexane and dichloromethane (1 : 1 ratio v/v) and analysed by gas chromatography linked mass spectrometry (GC-MS). Three peaks were found to be in higher concentration, which were identified as 6,11-dihydro-dibenz-b,e-oxepin-11-one (I); 2,6,10-dodecatrien-1-ol-3,7,11-trimethyl(Z) (II); and 1,2-benzene-dicarboxylic acid butyl(2-ethylpropyl) ester (III). Odour preference tests demonstrated that the first compound attracted conspecifics of the opposite sex. By contrast, the second and third compounds were found to attract both sexes. The results conclude that the clitoral gland of laboratory rat contains three major chemical compounds which have a unique function in maintaining social and reproductive status.

Animals↗
PubMed2001

Diffuse crescentic glomerulonephritis in bacterial endocarditis.

Renal involvement is common in patients with bacterial endocarditis. The most common bacteria are staphylococci and streptococci, and the commonest renal histopathological lesion is a diffuse proliferative and exudative type of glomerulonephritis. Very rarely, patients may present with an extensive glomerular epithelial crescent formation with a rapid deterioration in the renal function. This study reviews the published literature on diffuse crescentic glomerulonephritis in bacterial endocarditis and reports a 24-year-old male patient with endocarditis due to Capnocytophagia species, a gramnegative facultative anaerobic bacillus, which normally inhabits the oral cavity. Appropriate antibiotic therapy is essential to eradicate the infection. A brief course of corticosteroid therapy may be helpful in those with deteriorating renal function. Plasmapheresis may be useful in those with persistent hypocomplementemia, increased circulating immune complexes, and a progressive deterioration in the renal function. Removal of vegetation or valve replacement may be necessary. Prognosis is generally good.

Adult↗
PubMed2001

Protein digestibility-corrected amino acid scores for bean and bean-rice infant weaning food products.

Vegetable proteins are an integral part of infant weaning diets in Latin America. Protein quality in plant-based products, however, is constrained by amino acid composition and intrinsically present antinutritional factors. The goal of this study was to improve bean protein quality by utilizing fermentation and germination processing. The objectives were to determine if protein quality, as measured by Food and Agricultural Organization (FAO) approved True Protein Digestibility (TPD) and Protein Digestibility-Corrected Amino Acid Scores (PDCAAS), of formulated bean-based weaning products could be improved upon fermentation and germination and if protein quality could be further improved when processed beans were combined with cooked rice. Results showed that the highest TPD and PDCAAS values were obtained for cooked germinated beans combined with rice. The TPD values for products ranged from 80 to 91%, and the PDCAAS values were 0.38-0.51. There was no significant increase (P < 0.05) of either TPD or PDCAAS values upon fermentation. Germination increased TPD of cooked bean products; this increase was not, however, accompanied by an increase in PDCAAS. When combined with rice, the PDCAAS values for all bean products improved significantly, thus supporting the concept of cereal-legume complementation. In conclusion, this study showed the range of PDCAAS in processed black bean and bean-rice infant weaning food products. The potential for incorporation of these products into the diets of weaning age Latin American children would, however, be confirmed only after validation with growth or metabolic balance studies in human infants.

Amino Acids↗
PubMed2001

Iron and zinc bioavailability in rats fed intrinsically labeled bean and bean-rice infant weaning food products.

Beans are the core of the Latin American diet and contain iron and zinc. However, the bioavailability of these trace minerals from beans is low. The objective of this study was to determine if the bioavailability of iron and zinc could be improved with the use of fermentation and germination processing technologies. Black beans native to Costa Rica were grown hydroponically with either radioactive iron or zinc. The influence of fermentation and germination on iron and zinc bioavailability from intrinsically labeled infant weaning food products based on black beans and beans-rice was determined in rats. Mineral bioavailability was determined using whole-body (59)Fe retention for iron, and whole-body (65)Zn retention and incorporation of radiolabel into bone for zinc. Percent absorption of (59)Fe from fermented products ranged between 48.0 and 58.0. Percent absorption of (65)Zn ranged from 57.0 to 64.0. Fermentation did not increase iron bioavailability in rats fed fermented beans without rice. Fermentation of cooked beans significantly increased zinc retention. Germination significantly enhanced iron retention from cooked beans from 46 to 55% and from cooked beans-cooked rice from 34 to 48%. Germination significantly improved zinc absorption and retention from cooked beans without added rice.

Absorption↗