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Biomedical subjects

A Damodaran

Publications and source records attributed to A Damodaran.

17 recordsLinked to original sources
PubMed2005

Coastal resource complexes of South India: options for sustainable management.

India's coastal resource complexes were traditionally characterized by a continuum of 'common property resources' or 'commons' that stretched from the shores to the seas. The continuum aided the existence of sustainable livelihood systems for local communities. Today, fragmented policy approaches and economic welfare schemes have caused the disintegration of community control over the continuum. As a consequence, livelihood systems of local communities have declined. The introduction of coastal management guidelines in the 1990s has exacerbated the situation. With reference to a coastal village located in the State of Kerala in South West India, the paper describes the trajectory of unsustainable change that has taken place in the coastal area resource complexes of the country. The paper argues for restoring the continuum of commons in the study area through community driven systems of natural resource management that are based on networks of nested institutions.

Animals↗
PubMed2004

Role of keratinocytes in antigen presentation and polarization of human T lymphocytes.

Allergic contact dermatitis is a T-cell-mediated inflammatory skin disease in which interaction between skin keratinocytes and migrating T lymphocytes may play a critical part. In this study, the role of keratinocytes as allergen-/antigen-presenting cells (APCs) leading to activation of T lymphocytes is investigated using a human epidermal cell line A431. It is known that cultured cells do not express human leucocyte antigen (HLA) and hence can be used as APCs independent of HLA profile of both APCs and T cells from human volunteers. This cell line responded to common allergens and irritants by inducing or upregulating the cell-surface expression of HLA-DR, and intercellular adhesion molecule-1 and B7 mRNA transcripts in keratinocytes. In addition, allergen-primed A431 cells also induced allergen-specific proliferation of human T lymphocytes in cocultures. Anti-HLA-DR, interleukin-1alpha (IL-1alpha) antibodies and lysosomotropic agent chloroquine inhibited the proliferation. Allergens also upregulated cytokines IL-1alpha, granulocyte-macrophage colony-stimulating factor, Gro-alpha and IL-12 in keratinocytes. Further, keratinocytes activated by allergens induced polarization of activated T lymphocytes to the Th1 phenotype.

Antigen Presentation↗
PubMed2002

Therapeutic potential of yoga practices in modifying cardiovascular risk profile in middle aged men and women.

AIMS OF STUDY: To study effect of yoga on the physiological, psychological well being, psychomotor parameter and modifying cardiovascular risk factors in mild to moderate hypertensive patients. METHODS: Twenty patients (16 males, 4 females) in the age group of 35 to 55 years with mild to moderate essential hypertension underwent yogic practices daily for one hour for three months. Biochemical, physiological and psychological parameters were studied prior and following period of three months of yoga practices, biochemical parameters included, blood glucose, lipid profile, catecholmines, MDA, Vit. C cholinesterase and urinary VMA. Psychological evaluation was done by using personal orientation inventory and subjective well being. RESULTS: Results showed decrease in blood pressure and drug score modifying risk factors, i.e. blood glucose, cholesterol and triglycerides decreased overall improvement in subjective well being and quality of life. There was decrease in VMA catecholamine, and decrease MDA level suggestive decrease sympathetic activity and oxidant stress. CONCLUSION: Yoga can play an important role in risk modification for cardiovascular diseases in mild to moderate hypertension.

Adaptation, Physiological↗
PubMed2000

Effect of yogic practices on subjective well being.

Forty eight healthy volunteers who participated in the practice of yoga over a period of 4 months were assessed on Subjective Well Being Inventory (SUBI) before and after the course in order to evaluate the effect of practice of yoga on subjective feelings of well-being and quality of life. A significant improvement in 9 of the 11 factors of SUBI was observed at the end of 4 months, in these participants. The paper thus, reiterates the beneficial effects of regular practice of yoga on subjective well being.

Adult↗
PubMed1999

Stress due to exams in medical students--role of yoga.

A student under optimal stress does bring out his or her best, However extremes of stress can result in stress induced disorders and deteriorating performance. Can yoga be of benefit in stress induced effects in medical students? The present study was conducted in first MBBS students (n = 50) to determine the benefit if any of yogic practices on anxiety status during routine activities and prior to examination. Feedback scores were assessed to determine how the students had benefited from the practices. Anxiety status as assessed by Spillberger's anxiety scale showed a statistically significant reduction following practice. In addition the anxiety score which rose prior to exams showed a statistically significant reduction on the day of exam after practice. These results point to the beneficial role of yoga in not only causing reduction in basal anxiety level but also attenuating the increase in anxiety score in stressful state such as exams. The results of the exam indicated a statistically significant reduction in number of failures in yoga group as compared to the control group. The improvement in various parameters such as better sense of well being, feeling of relaxation, improved concentration, self confidence, improved efficiency, good interpersonal relationship, increased attentiveness, lowered irritability levels, and an optimistic outlook in life were some of the beneficial effects enjoyed by the yoga group indicated by feedback score.

Adult↗
PubMed1997

Ectopic production and processing of atrial natriuretic peptide in a small cell lung carcinoma cell line and tumor from a patient with hyponatremia.

BACKGROUND: Tumors and tumor cell lines from two patients with small cell lung carcinoma (SCLC) (one with and one without hyponatremia) were studied. Ectopic production and prohormone processing of atrial natriuretic peptide (ANP) were investigated to determine if a biologically active peptide was produced in a tumor cell line from a patient with hyponatremia and no evidence of arginine vasopressin (AVP) production. METHODS: Ribonuclease (RNase) protection assays were performed on mRNA isolated from tumors and tumor cell lines established from two SCLC patients, one with and one without hyponatremia. Cellular extracts and conditioned media were studied using reversed-phase high performance liquid chromatography (HPLC) to determine the immunoreactive form of ANP. Tumor cell line sonicates were studied for subcellular localization of enzymatic activity that cleaved pro-ANP peptide substrates. RESULTS: RNase protection assays showed a 200-base pair protected fragment in the mRNA isolated from the tumor and tumor cell line from the patient with hyponatremia (Patient 4). HPLC characterization of the cellular extract and conditioned medium from the tumor and tumor cell line from Patient 4 demonstrated ANP immunoreactivity in the same fraction as ANP- (S99-Y126). The tumor cell line extract that localizes to a subcellular fraction enriched for lysosomes and secretory organelles contains a 60-kilodalton molecular weight protein with enzyme activity that hydrolyzes synthetic pro-ANP substrates and catalyzes the formation of ANP-(S99-Y126). CONCLUSIONS: A tumor cell line from a patient with hyponatremia was able ectopically to produce, process, and secrete ANP in the same immunoreactive form as the biologically active molecule. Preliminary studies show that tumor cell line NCI-H1284 contains an enzyme that can cleave precursors at the same amino acid sequences needed to produce ANP-(S99-Y126) from pro-ANP.

Atrial Natriuretic Factor↗
PubMed1997

Analysis of DNA ploidy and expression of tumour-associated antigens on human oral carcinomas xenografted in nude mice.

Human squamous cell carcinomas (SCC) of the oral cavity were successfully established as xenografts in nude mice. Tumours with higher malignancy scores and involvement of lymph nodes in patients were more readily accepted as xenografts in nude mice. The xenografted tumours were characterised with respect to morphology, histology, DNA index and expression of tumour-associated antigens (TAA). Flow cytometric analysis of cellular DNA content revealed that many of the xenografts retained the parent tumour DNA pattern while some of the xenografts showed progression to aneuploidy. All the xenografted tumours expressed TAA recognised by monoclonal antibody (MAb) 3F8E3. On Western blotting, MAb 3F8E3 recognised proteins of molecular weight 62-64 kDa on parent and xenografted tumours. In general, the xenografts reflect many of the characteristics of the tumours from which they were derived and may provide a useful model for investigating newer approaches of treatment and diagnosis.

Animals↗
PubMed1995

Preparations of psi-peptide bond and peptide-aldehyde inhibitors of atrial granule serine proteinase, a candidate processing enzyme of pro-atrial natriuretic factor.

Pseudo-peptide bond inhibitors (psi-bond inhibitors) and peptide-aldehyde inhibitors of atrial granule serine proteinase, the candidate processing enzyme of pro-atrial natrieuretic factor, are prepared in high yield and purity by novel synthetic routes. The psi-bond compounds retain essential residues for enzyme binding, but place the enzyme inhibition site in the midst of the peptide sequence. Thus, Bz-APR-psi-LR and Bz-APR-psi-SLRR can be considered "readthrough inhibitors" of atrial granule serine proteinase. The most potent psi-peptide, Bz-APR-psi-SLRR (IC50=250 microM), is about fivefold less potent than the best peptide-aldehyde inhibitor (EACA-APR-CHO), and both the psi-bond and peptide-aldehyde compounds are competitive, reversible inhibitors of the enzyme. The psi-bond peptides containing two C-terminal Arg residues are three- to tenfold more potent than the analogous compounds containing only one C-terminal Arg residue, confirming the importance of both Arg residues in the enzyme processing recognition site. As expected, because of their moderate potencies, the psi-peptides are not useful affinity ligands for purification of atrial granule serine proteinase, but both peptide aldehydes are effective affinity ligands.

Aldehydes↗
PubMed1995

N-terminal sequence analysis of atrial granule serine proteinase purified by affinity chromatography.

Atrial granule serine proteinase is considered the leading candidate endoproteolytic processing enzyme of pro-atrial natriuretic factor. Its cleavage specificity is directed toward a monobasic amino acid processing site, and as such, the atrial enzyme is distinguished from the family of prohormone convertases which act at dibasic amino acid processing sites. To delineate the molecular mechanisms which distinguish monobasic from dibasic amino acid-directed processing enzymes, pure atrial enzyme is needed for sequence determination leading to molecular cloning, and for preparation of antisera. An affinity chromatography purification scheme seemed a logical modification of our established procedures to yield suitable amounts of enzyme for further studies [Damodaran and Harris (1995, J. Protein Chem., this issue] formed ineffective affinity ligands, even though these compounds contain essential residues on either side of what would be the scissile bond in a peptide substrate. On the other hand, tripeptide aldehydes (based on the substrate recognition sequence of the atrial enzyme) linked to Sepharose formed effective affinity matrices, permitting purification of the enzyme in a single step from a subcellular fraction enriched for atrial granules and lysosomes. Hence, the enzyme was purified 2000-fold in 90% overall yield, and subjected to N-terminal sequence analysis through 26 residues. The sequence determined, XXPEAAGLPG[R,L]GNPVP[F,G]R[Q,I]XY[G,E]XR(N,A]V, indicates that the atrial enzyme is unique, showing little sequence homology to other proteins in the database.

Amino Acid Sequence↗
PubMedDate not supplied

Characterization of tumor-associated antigens on human oral squamous cell carcinomas using monoclonal antibody 3F8E3.

Tumor associated antigen (TAA) on oral squamous cell carcinoma (SCC) was characterized using the monoclonal antibody (MAb) 3F8E3. Flow cytometric analysis revealed a varying degree of reactivity of MAb 3F8E3 to TAA on oral tumor cells. Pretreatment of SCC cells with pronase and trypsin annulled the reactivity of MAb 3F8E3. Sodium metaperiodate (NaIO4) and neuraminidase marginally enhanced the binding of 3F8E3 on oral SCC cells. The studies indicate that the TAA recognized by MAb 3F8E3 on oral tumors is a protein moiety. On Western blotting MAb 3F8E3 showed reactivity to proteins with a molecular weight of 60-66 kDa on oral tumor lysates. MAb 3F8E3 reacted strongly to recombinant human hsp60 and 70 in ELISA. The results suggest that MAb 3F8E3 may react to an epitope expressed on a family of heat shock proteins.

Animals↗