Biomedical subjects

S Jeganathan

Publications and source records attributed to S Jeganathan.

11 recordsLinked to original sources

PubMed2006

eEF1A2 activates Akt and stimulates Akt-dependent actin remodeling, invasion and migration.

eEF1A2 (eukaryotic protein elongation factor 1 alpha 2) is a protein translation factor that is likely a human oncogene by virtue of its capacity to transform mammalian cells and its high expression in tumors of the ovary, breast and lung. Here, we show that expression of eEF1A2 is sufficient to stimulate the formation of filopodia in BT549 human breast cancer cells and non-transformed Rat2 cells. Filopodia formation in eEF1A2-expressing cells is dependent on the activity of phosphatidylinositol-3 kinase (PI3K), and the ROCK and Akt kinases. Furthermore, eEF1A2 expression is sufficient to activate Akt in a PI3K-dependent fashion and inactivation of eEF1A2 by short interfering RNA reduces Akt activity. Using breast cancer cell line BT 549, we show that eEF1A2 expression stimulates cell migration and invasion in a largely PI3K- and Akt-dependent manner. These results suggest that eEF1A2 regulates oncogenesis through Akt and PI3K-dependent cytoskeletal remodeling.

Actins↗

PubMed2006

Spectroscopic approaches to the conformation of tau protein in solution and in paired helical filaments.

The abnormal aggregation of the microtubule-associated protein tau into paired helical filaments is one the hallmarks of Alzheimer's disease. This aggregation is based in the partial formation of beta-structure. In contrast, the soluble protein shows a mostly random coil structure, as judged by circular dichroism, Fourier transform infrared, X-ray scattering and biochemical assays. Here, we review the basis of the natively unstructured character of tau, as well as recent studies of residual structure and long-range interactions between different domains of the protein. Analysis of the primary structure reveals a very low content of hydrophobic amino acids and a high content of charged residues, both of which tend to counteract a well-folded globular state of proteins. In the case of tau, the low overall hydrophobicity is sufficient to explain the lack of folding. This is in contrast to other proteins which also carry an excess charge at physiological pH. By tryptophan scanning mutagenesis and fluorimetry we found that most of the sequence is solvent exposed. Analysis of the hydrodynamic radii confirms a mostly random coil structure of various tau isoforms and tau domains. The proteins can be further expanded by denaturation with GdHCl which indicates some global folding. This was substantiated by a FRET-based approach where the distances between different domains of tau were determined. The combined data show that tau is mostly disordered and flexible but tends to assume a hairpin-like overall fold which may be important in the transition to a pathological aggregate.

Animals↗

PubMed1997

Denture stomatitis in an elderly edentulous Asian population.

Denture stomatitis is a common oral disease in denture wearers. Multiple aetiological and predisposing factors are believed to be responsible for its initiation and progression. The aim of this study was to assess the relationship between denture age, denture hygiene habits, denture wearing and denture cleanliness in an elderly edentulous Asian population. Seventy-five edentulous patients, all wearing maxillary complete dentures were divided into two groups. The test group comprised 36 patients (14 male and 22 female) with Type II denture stomatitis. The control group comprised 39 subjects (14 male and 25 female) with clinically healthy palatal mucosa. A standardized interview and clinical appraisal were carried out. The dye disclosing method was used to assess denture cleanliness and the resultant staining pattern scored. Statistical appraisal between the two groups revealed significant differences in denture hygiene habits (P < 0.05), denture wearing behaviour (P < 0.01) and denture cleanliness (P < 0.01). No significant difference was observed in the age of dentures between the test group and controls (P > 0.05). In the studied Asian edentulous population, a relationship between denture hygiene habits, denture wearing behaviour and denture cleanliness to the presence of denture stomatitis was observed.

Case-Control Studies↗

PubMed1996

The use of removable partial dentures amongst private dental practitioners in Singapore.

A questionnaire survey was carried out in 1995 amongst university trained general dental practitioners in the city state of Singapore to assess the use of removable partial dentures (RPD). 37% of the original sample of 469 completed and returned the questionnaire. The results of this survey indicate that RPDs are a common treatment modality in Singapore. Acrylic partial dentures appear to be the preferred choice for RPD treatment. The work profile of those who had a postgraduate qualification in removable prosthodontics did not differ from that of the general dental practitioner.

Acrylic Resins↗

PubMed1996

A clinically viable index for quantifying denture plaque.

A denture plaque index using the dye disclosing method was evaluated in 24 patients with Type II denture stomatitis and 17 control subjects with healthy palatal mucosa. Patients with denture stomatitis had statistically significantly higher plaque scores than did controls, indicating a quantitative increase in denture plaque in patients with denture stomatitis. When this plaque index was tested by two examiners for intraexaminer and interexaminer reproducibility, it yielded a 92% to 96% reproducibility. The plaque index used in this study seems to satisfy the criteria for an ideal clinical index: It is simple, reliable, reproducible, and economical and can be carried out in the shortest possible time in a clinical setting.

Dental Plaque↗

PubMed1994

Copper electroplating of non-aqueous elastomeric impression materials: a subjective appraisal of their platability.

Electroplating of non-aqueous elastomeric impression materials is a well-documented technique. Electroplated silver or copper plated dies have many clinical advantages compared to other die systems. Silver electroplating appears to be used more frequently than copper electroplating. Utilization of silver for electroplating requires an appreciation of financial and biohazard considerations. Research on compatibility of copper electroplating with current non aqueous elastomeric impression materials is lacking. Samples of currently used non aqueous elastomeric impression materials were used to register impressions of conventional crown preparations on a typodont. These impressions were electroplated to form copper plated dies. The surface qualities of the dies were evaluated. Not all impression materials produced visually acceptable or workable copper plated dies.

Color↗

PubMed1993

Common faults in complete dentures: a review.

Complete-denture therapy involves a complex interplay between biologic demands and technical limitations. Success with complete-denture therapy is reportedly high. Dissatisfied denture patients, although few, do exist. This paper reviews some of the common faults reported with complete dentures.

Denture Retention↗

PubMed1992

Immunodiagnosis in oral candidiasis. A review.

Detection of anti-Candida antibodies in sera and saliva of patients with oral candidiasis has been regarded as a valuable laboratory technique in the diagnosis of the lesion. However, despite considerable research, the value of candidal immunodiagnosis remains controversial. Conflicting conclusions about the sensitivities and specificities of these techniques as applied to human sera and saliva have appeared. These controversies have arisen because of the use of different antigen preparations and immunologic techniques. For the present, the use of purified cytoplasmic protein antigen of Candida albicans and the ELISA technique seems to be the most reliable laboratory method.

Antibodies, Fungal↗

PubMed1992

Denture stomatitis--a review of the aetiology, diagnosis and management.

Denture stomatitis is a common recurring problem of the denture wearers. The aetiology of the disease includes infection, trauma and probably a defect in the host defence mechanism. Current thinking suggests an interplay of most of these factors in the pathogenesis of the disease. The extent of interplay of these factors is still a controversy. Candida albicans has been implicated as the causative organism. However, in the light of recent research it is debatable if it is the only causative organism. Recently, cases resistant to antifungal therapy have been reported. In such cases other micro-organisms have been isolated. At the moment, comprehensive management includes meticulous denture hygiene together with anti-fungal or antibacterial therapy and correction of denture faults.

Candidiasis, Oral↗

PubMed1987

Immunoglobulin A1 and A2 subclass of salivary antibodies to Candida albicans in patients with oral candidosis.

Immunoglobulin A antibody titres to a cytoplasmic protein extract of Candida albicans were determined by ELISA in saliva from 20 patients with oral candidosis and 21 controls. Patients had significantly increased levels of salivary IgA anti-Candida antibodies when compared with controls (P less than 0.001). Antibody levels were associated with IgA1 subclass in 90% of the patients; in contrast, IgA2 subclass was predominant in 67% of the controls. Antifungal therapy resulted in significantly decreased IgA1 titres (P less than 0.05) whilst the mean IgA2 antibody titre remained unchanged. The results indicate that Candida infection may change the subclass pattern of salivary IgA antibodies.

Adult↗

PubMedDate not supplied

Conformationally restricted mimics of vitamin D rotamers.

Drug developments in the vitamin D field have continued to focus on structure-function studies of analogs produced by chemically modifying the structure of 1alpha,25-dihydroxyvitamin D(3) (1,25-D3) and its metabolites. Direct structural information gleaned from X-ray crystallographic or NMR studies regarding the ligand-receptor complex and other guest-host systems, which are likely involved in initiating biologic responses, also offers potential insight into drug design. Evidence has accrued suggesting that topologically different conformers of 1,25-D3 may bind to proteins in different ways, including the induction of different conformations of protein. This paper concerns our progress on the chemical synthesis of analogs (e.g. ansa-steroids, suprasterols, vinylallenes and other analogs) conformationally locked or at least rotationally restricted to mimic higher energy conformers of 1,25-D3.

Animals↗