Biomedical subjects

V Kumaraswami

Publications and source records attributed to V Kumaraswami.

At least 19 recordsLinked to original sources

PubMed2006

A simple and rapid liquid chromatography method for simultaneous determination of zidovudine and nevirapine in plasma.

We describe a simple, fast, isocratic, reversed-phase high performance liquid chromatographic method for simultaneous determination of plasma zidovudine and nevirapine with UV detection at 260 nm. The method involves liquid-liquid extraction with ethyl acetate and using 3-isobutyl 1-methyl xanthine as internal standard. The system requires a C(18) column (150 mm x 4.6 mm I.D.) and a mobile phase composed of potassium dihydrogen phosphate (15 mM; pH 7.5) and acetonitrile in the ratio of 80:20 (v/v). The assay was linear from 0.025 to 10.0 microg/ml for zidovudine and 0.05 to 10.0 microg/ml for nevirapine. The intra- and inter-day variations were less than 10% for both the drugs. The method was specific and sensitive enough to allow quantification of zidovudine and nevirapine in concentrations observed clinically. The average recoveries of zidovudine and nevirapine from plasma were 95 and 94%, respectively. The method was applied to a pharmacokinetic study in HIV-infected patients who were receiving antiretroviral treatment with zidovudine and nevirapine containing regimens. The method spans the blood concentration range of clinical interest. Due to its simplicity, the assay can be used for pharmacokinetic studies and therapeutic drug monitoring in patients taking a combination treatment of zidovudine and nevirapine.

Adult↗

PubMed2006

Cutting edge: diminished T cell TLR expression and function modulates the immune response in human filarial infection.

Patent lymphatic filariasis is characterized by profound Ag-specific T cell hyporesponsiveness with impaired IFN-gamma and IL-2 production. Because T cells have been shown to express a number of TLR and to respond to TLR ligands, we hypothesized that diminished T cell TLR function could partially account for the T cell hyporesponsiveness in filariasis. T cells expressed TLR1, TLR2, TLR4, and TLR9, and the baseline expression of TLR1, TLR2, and TLR4, but not TLR9 was significantly lower in T cells of the filarial-infected individuals compared with the uninfected individuals (both endemic and nonendemic). TLR function was significantly diminished in the T cells of filarial-infected individuals based on decreased T cell activation/cytokine production in response to TLR ligands. Thus, diminished expression and function of T cell TLR is a novel mechanism underlying T cell immune tolerance in lymphatic filariasis.

Animals↗

PubMed2006

Simple and rapid liquid chromatography method for determination of efavirenz in plasma.

A simple and rapid high performance liquid chromatographic method for determination of efavirenz in human plasma was developed. The method involved extraction of sample with ethyl acetate and analysis using a reversed-phase C(18) column (150 mm) with UV detection. The assay was linear from 0.0625 to 10.0 microg/ml. The method was specific for efavirenz estimation and the drug was stable in plasma up to one month at -20 degrees C. The average recovery of efavirenz from plasma was 101%. Due to its simplicity, the assay can be used for pharmacokinetic studies and therapeutic drug monitoring of efavirenz.

Alkynes↗

PubMed2006

Regulatory networks induced by live parasites impair both Th1 and Th2 pathways in patent lymphatic filariasis: implications for parasite persistence.

Patent lymphatic filariasis is characterized by a profound down-regulation of immune responses with both parasite Ag-specific tolerance and bystander suppression. Although this down-regulation is confined to the Th1 arm of the immune system in response to parasite Ag, we hypothesized a more generalized suppression in response to live parasites. Indeed, when we examined the cytokine profile of a cohort of filaria-infected (n = 10) and uninfected (n = 10) individuals in response to live infective-stage larvae or microfilariae of Brugia malayi, we found significant impairment of both Th1 and Th2 cytokines characterized by diminished production of IFN-gamma, TNF-alpha, IL-4, IL-5, and IL-10 in infected patients. The molecular basis of this impaired Th1/Th2 response was examined, and we identified three major networks of immunoregulation and tolerance. First, impaired induction of T-bet and GATA-3 mRNA underlies the Th1/Th2 deficiency in infected individuals. Second, regulatory networks, as evidenced by significantly increased expression of Foxp3 (natural regulatory T cell marker) and regulatory effectors such as TGF-beta, CTLA-4, PD-1, ICOS, and indoleamine 2,3-dioxygenase play an important role in immunosuppression. Third, the compromise of effector T cell function is mediated by the enhanced induction of anergy-inducing factors cbl-b, c-cbl (cbl is abbreviation for Casitas B lymphoma), Itch, and Nedd4. Indeed, blocking CTLA-4 or neutralizing TGF-beta restored the ability to mount Th1/Th2 responses to live parasites and reversed the induction of anergy-inducing factors. Hence, we conclude that a profound impairment of live parasite-specific Th1 and Th2 immune responses occurs in lymphatic filariasis that is governed at the transcriptional level by a complex interplay of inhibitory mediators.

Animals↗

PubMed2006

Relationship of ARTI to incidence and prevalence of tuberculosis in a district of south India.

OBJECTIVE: To validate the currently used empirical relationship between annual risk of tuberculous infection (ARTI) and incidence and prevalence of smear-positive cases. SETTING: Two disease surveys to estimate the prevalence and incidence of tuberculosis (TB) among adults in Tiruvallur district, south India, and a tuberculin survey to estimate the ARTI among children. RESULTS: The incidence of TB was estimated to be 82 and prevalence 210 per 100,000 population and ARTI 1.6%. We estimated that 1% ARTI corresponded to 51 new and 131 prevalent cases. CONCLUSION: The currently used empirical relationship between ARTI and incidence can be used by programme managers as an effective monitoring tool.

Adult↗

PubMed2006

Coincident filarial, intestinal helminth, and mycobacterial infection: helminths fail to influence tuberculin reactivity, but BCG influences hookworm prevalence.

The prevalence of helminth and tuberculosis infections is high in South India, whereas Bacille-Calmette-Guerin (BCG) vaccine efficacy is low. Our aim was to determine whether concurrent helminth infection alters the ability to mount a delayed-type hypersensitivity response to tuberculin. In a cross-sectional study in southern India, individuals 6-65 years of age were screened for intestinal helminths, circulating filarial antigenemia, tuberculin reactivity, active tuberculosis, and history of BCG vaccination; 54% were purified protein derivative (PPD) positive, 32% had intestinal helminth infection, 9% were circulating filarial antigen positive, and 0.5% had culture-confirmed active tuberculosis. Only age and BCG vaccination were significantly associated with PPD reactivity; however, BCG vaccination was associated with a lower prevalence of hookworm infection relative to those without prior BCG vaccination. Neither intestinal helminth infection nor filarial infection was associated with diminished frequencies of PPD positivity. Our findings suggest that preceding helminth infection does not influence significantly the delayed-type hypersensitivity response to tuberculin.

Adolescent↗

PubMed2005

Diminished expression and function of TLR in lymphatic filariasis: a novel mechanism of immune dysregulation.

Lymphatic filariasis is a disease characterized by immune dysregulation involving APC and T cell populations. To assess the contribution of TLR in mediating this dysregulation, we examined the expression of TLR1, TLR2, TLR4, and TLR9 on B cells and monocytes of filaria-infected and uninfected individuals. Baseline expression of TLR was significantly lower in B cells but not in monocytes of the filaria-infected group compared with the uninfected group. Upon stimulation with filarial Ag, a diminished up-regulation of TLR was observed in both B cells and monocytes of infected individuals. Finally, stimulation of B cells and monocytes with TLR ligands resulted in decreased B cell and monocyte activation/cytokine production, indicating a state of immune tolerance. This dysregulation is associated with diminished CD4(+) T cell production of IFN-gamma and IL-5. The diminished expression and function of TLR is thus a likely consequence of chronic Ag stimulation and could serve as a novel mechanism underlying the dysfunctional immune response in filariasis.

Adult↗

PubMed2005

Chemokine receptors of T cells and of B cells in lymphatic filarial infection: a role for CCR9 in pathogenesis.

We examined the expression of chemokine receptors on the surfaces of T cells and B cells from 27 individuals either with lymphatic filarial disease (lymphedema), with the asymptomatic or subclinical form of filarial infection, or without filarial infection. Individuals with lymphedema exhibited increased percentages of CCR9-expressing T cells and CCR9-expressing B cells and decreased percentages of both CXCR1-and-CXCR3-expressing T cells and CXCR1-and-CXCR3-expressing B cells, compared with asymptomatic or uninfected individuals. A significant correlation was found between the grade of lymphedema and the percentage of CCR9-expressing T cells and CCR9-expressing B cells. The percentages of CCR9-expressing T cells and CCR9-expressing B cells from patients with lymphedema was significantly up-regulated in response to live, infective-stage larvae of Brugia malayi but not to microfilariae of this parasite. Finally, individuals with lymphedema had significantly higher concentrations of interleukin-8, macrophage inflammatory protein (MIP)-1alpha , MIP-1beta , monocyte chemotactic protein 1, thymus-and-activation-regulated chemokine, and interferon-inducible protein 10 in their serum than did uninfected individuals. These results suggest that chemokine receptors (particularly CCR9) are involved in the pathogenesis of lymphatic filarial disease and that trafficking of particular cellular subsets may influence clinical outcome.

Adult↗

PubMed2005

Transcriptional control of impaired Th1 responses in patent lymphatic filariasis by T-box expressed in T cells and suppressor of cytokine signaling genes.

T-bet (T-box expressed in T cells) and GATA-3 are transcription factors that play a critical role in the development of Th1 and Th2 cells, as do genes of the SOCS (suppressor of cytokine signaling) family, albeit indirectly. Another transcription factor, Foxp3, is a master regulator of natural regulatory T cells (Tregs). To identify the role of these factors in impaired Th1 responses of patent filarial infection, analysis of cytokine, SOCS, and transcription factor mRNA expression was performed on purified T cells of filaria-infected individuals (n = 6) and uninfected controls (n = 6). As expected (and in contrast to cells of uninfected individuals), there was a significant depression of gamma interferon (IFN-gamma) and a concomitant increase in interleukin-4 (IL-4), IL-5, and IL-10 mRNA expression following stimulation with parasite antigen (BmA) but not with a polyclonal T-cell (anti-CD3) stimulus. T-bet (but not GATA-3) was expressed at significantly lower levels in cells of filaria-infected individuals in response to BmA compared with those from the uninfected group, accounting, at least partially, for the diminished IFN-gamma expression. Second, we found no significant differences in expression of Foxp3 between the two groups, although induction of Foxp3 expression correlated with induced expression levels of IL-10, implicating Tregs in the IL-10 expression seen. Finally, parasite-specific T-cell expression of SOCS-1, SOCS-5, and SOCS-7 was significantly diminished among infected patients; in contrast, expression of SOCS-3 increased. Our data therefore indicate that the impaired Th1 responses observed in patent lymphatic filariasis are associated with decreased expression of T-bet, SOCS-1, SOCS-5, and SOCS-7 and increased expression of SOCS-3 in T cells.

Adult↗

PubMed2005

Genetic polymorphisms of eosinophil-derived neurotoxin and eosinophil cationic protein in tropical pulmonary eosinophilia.

Because eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) are critical in the pathogenesis of tropical pulmonary eosinophilia (TPE), we analyzed genetic polymorphisms of both in 181 individuals from southern India with varying clinical manifestations of Wuchereria bancrofti infection (including 26 with TPE). Using haplotype frequency analysis, we identified four known (of nine) and two novel haplotypes for EDN (1, 2, 7, 8, 10, and 11). For ECP, five (of seven known) haplotypes (1-5) were identified. Although we found no significant association between frequencies of EDN and ECP polymorphisms and TPE development, we observed a unique pattern of EDN and ECP polymorphism distribution among this population. Genotype TT at locus 1088 of ECP in one TPE patient was not observed in any other clinical group. Although the EDN and ECP polymorphisms appear unlikely to be associated with the development of TPE, further analyses will be more definitive.

Animals↗

PubMed2003

Localized eosinophil degranulation mediates disease in tropical pulmonary eosinophilia.

To explore the mechanisms underlying the eosinophil-mediated inflammation of tropical pulmonary eosinophilia (TPE), bronchoalveolar lavage (BAL) fluid, serum, and supernatants from pulmonary and blood leukocytes (WBC) from patients with acute TPE (n = 6) were compared with those obtained from healthy uninfected individuals (n = 4) and from patients with asthma (n = 4) or elephantiasis (n = 5). Although there were no significant differences in the levels of interleukin-4 (IL-4), IL-5, IL-13, eotaxin, granulocyte-macrophage colony-stimulating factor, RANTES, or eosinophil cationic protein, there was a marked increase in eosinophil-derived neurotoxin (EDN) both systemically and in the lungs of individuals with TPE compared to each of the control groups (P < 0.02). Moreover, there was a compartmentalization of this response, with EDN levels being higher in the BAL fluid than in the serum (P < 0.02). Supernatants from WBC from either whole blood or BAL cells were examined for chemokines, cytokines, eosinophil degranulation products, and arachidonic acid metabolites. Of the many mediators examined-particularly those associated with eosinophil trafficking-only EDN (in BAL fluid and WBC) and MIP-1alpha (in WBC) levels were higher for TPE patients than for the non-TPE control groups (P < 0.02). These data suggest it is the eosinophilic granular protein EDN, an RNase capable of damaging the lung epithelium, that plays the most important role in the pathogenesis of TPE.

Adolescent↗

PubMed2003

A qualitative study of the perceptions, practices and socio-psychological suffering related to chronic brugian filariasis in Kerala, southern India.

Lymphatic filariasis is a major health problem in many parts of the tropical world. Although the disease itself is rarely fatal, the disability caused by the swollen extremities, the acute attacks of adenolymphangitis and the consequent sufferings of those afflicted are considerable. The economic burden imposed by lymphatic filariasis is not fully quantified and information on the social and psychological problems caused by the disease is scanty. Semi-structured interviews were therefore used, in southern India, to assess the perceptions, practices and socio-psychological problems of 127 patients with brugian filariasis. The patients were aware of the causative factors and the precautions to be taken to prevent progression of the disease. However, depression and loss of job opportunities were common in the study population. Patients also complained that the disease eroded their standing in the community and diminished their prospects of marriage. Awareness of these factors will be of help in planning suitable disability-management packages, including the rehabilitation of those who find it difficult to carry on with their existing jobs because of the severity of their disease.

Activities of Daily Living↗

PubMed2003

A qualitative study on the feasibility and benefits of foot hygiene measures practiced by patients with brugian filariasis.

Disability alleviation is an important component of 'Global Programme for Elimination of Lymphatic Filariasis'. In Brugia malayi infection the disability is largely due to acute attacks of adenolymphangitis (ADL), which frequently prevent patients from attending their normal activities, causing much suffering and economic loss. The foot care programme has been shown to reduce the frequency and severity of these episodes. In the present study we used semi-structured interviews to evaluate the impact of the foot care in 127 patients with brugian filariasis. They were previously trained in this procedure and were advised to practice it regularly, unsupervised. All except one could recollect the various components of foot hygiene and were practicing it regularly. They were aware of the factors causing ADL attacks and were able to avoid them. Majority (95.2%) expressed their happiness with the relief provided by foot care, which prevented or reduced the ADL episodes. The motivation was such that they transmitted this knowledge to others suffering in the community and even physically helped them to carry out foot care. This study fully endorses the advocacy of foot care programme as an easy to carry out, effective, sustainable and economically feasible procedure to prevent acute ADL attacks.

Animals↗

PubMed2002

Efficacy and sustainability of a footcare programme in preventing acute attacks of adenolymphangitis in Brugian filariasis.

Lymphatic filariasis is associated with considerable disability related to the intensity and frequency of acute adenolymphangitis (ADL) attacks. The global programme for elimination of lymphatic filariasis emphasizes the need to combine transmission control with alleviation of disability. Footcare aimed at the prevention of secondary bacterial infections is the mainstay of disability alleviation programmes. We evaluated the efficacy and sustainability of an unsupervised, personal footcare programme by examining and interviewing 127 patients who had previously participated in a trial that assessed the efficacy of diethylcarbamazine, penicillin and footcare in the prevention of ADL. During the trial period these patients had been educated in footcare and were supervised. During the unsupervised period, which lasted 1 year or longer, 47 patients developed no ADL, and ADL occurred less frequently in 72.5%. Most patients were practising footcare as originally advised, unsupervised and without cost, which proves that such a programme is sustainable and effective.

Acute Disease↗

PubMed2002

Pattern recognition technique in immunological antigenic tests to identify Mycobacterium tuberculosis infection.

UNLABELLED: The importance of a diagnostic test that is simple and quick to identify Mycobacterium tuberculosis infection needs no emphasis. The tuberculin skin test (TST - 1 TU RT23) is the diagnostic tool for identifying M. tuberculosis infection at present. The test reaction on the skin is measured after 48-72 h. It is observed that often multi-modes are seen, when the reactions are drawn as a graph and the bimodality is seen very feebly. Because of the difficulties in the administration of TST, several serological tests were developed over three decades, but none of the studies showed the desired results. One study to evaluate purified protein derivative (PPD) antigen resulted in a claim of 80% sensitivity and 4% false-positivity rate (14), while other researchers were not able to obtain similar results. In addition, several problems were encountered due to the non-availability of antigens, and data analyses from an ELISA-based diagnostic test showed considerable overlap of distributions of optical density (OD) values among patients and healthy individuals (10). Classical statistical techniques cannot explain the cause of these overlaps. Hence, an attempt is made in this article to resolve these difficulties by the pattern recognition technique (PRT). The technique lies in splitting the data into clusters using a supervised algorithm. The data set is normally split into a training set, a test set and a validation set. The PRT gets "trained" through the training data set until the infected and uninfected groups of individuals are correctly classified. The training occurs based on an algorithm on the training set. On successful completion of the training, this technique is further tested and validated in the respective data sets. SETTING: A total of 273 finger-prick specimens were collected from five categories (Al, A2, B, C, D, E) of subjects not vaccinated with (bacille Calmette Guerin) (BCG) from Trivellore BCG Trial area adopted by the Tuberculosis Research Center, Chennai, India. OBJECTIVE: The study was conducted with the primary aim of evaluating purified antigens--r38 kDa, PPD and 30 kDa--for their usefulness as diagnostic tools and to test the applicability of the PRT in the evaluation of diagnostic tests. Individuals in two main categories (definitely not infected categories Al, A2 and D, and definitely infected categories B, E and C based on reaction to TST) were assembled for the purpose. RESULTS: The overall PRT performance of 30 kDa was 72.3% sensitivity and 90.9% specificity for identifying M. tuberculosis infection, while the r38 kDa antigen recorded a sensitivity of 73.8% and a specificity of 84.6%. In the case of PPD, the results were not promising. CONCLUSION: This paper on ELISA-based diagnostic tests attempts to implement an optimal decision support system through PRT that would identify the outcome (as infected or non-infected) based on the OD values. The PRT was able to predict the outcome for individual suspects. Further, Kullback-Leibler distance measurement has validated the PRT in distinguishing infected individuals from healthy subjects (based on the OD values).

Adolescent↗

PubMed2002

The pharmacokinetics, safety and tolerability of the co-administration of diethylcarbamazine and albendazole.

The pharmacokinetics, safety and tolerability of single, oral doses of diethylcarbamazine (DEC) and albendazole, given alone or in combination, were investigated in a double-blind, randomized and placebo-controlled trial involving 42 amicrofilaraemic subjects living in an area of India where lymphatic filariasis is endemic. The subjects (34 males and eight females, aged 18-52 years and weighing 46-66.5 kg) were randomly allocated to one of the three drug groups. Fourteen were given just DEC (6 mg/kg), another 14 were given just albendazole (400 mg) and the remaining 14 were given both DEC (6 mg/kg) and albendazole (400 mg). Blood samples for pharmacokinetic study were collected at specified intervals before and after drug administration. Plasma concentrations of DEC and albendazole/albendazole sulphoxide were estimated using gas chromatography and HPLC, respectively. The safety and tolerability of the treatments were evaluated through clinical and laboratory assessments. Both the DEC and albendazole were well tolerated when given alone or in combination, no adverse events being observed. In all three treatment groups, the drugs were rapidly absorbed from the gastro-intestinal tract although there was marked inter-individual#10; variation. The pharmacokinetics of DEC, albendazole and albendazole sulphoxide were similar, whether each drug was given alone or in combination. These results indicate that there is no adverse pharmacokinetic or pharmacodynamic reason why DEC and albendazole should not be co-administered to control lymphatic filariasis.

Administration, Oral↗

PubMed2001

Genetic polymorphisms in molecules of innate immunity and susceptibility to infection with Wuchereria bancrofti in South India.

A pilot study was conducted to determine if host genetic factors influence susceptibility and outcomes in human filariasis. Using the candidate gene approach, a well-characterized population in South India was studied using common polymorphisms in six genes (CHIT1, MPO, NRAMP, CYBA, NCF2, and MBL2). A total of 216 individuals from South India were genotyped; 67 normal (N), 63 asymptomatic microfilaria positive (MF+), 50 with chronic lymphatic dysfunction/elephantiasis (CP), and 36 tropical pulmonary eosinophilia (TPE). An association was observed between the HH variant CHIT1 genotype, which correlates with decreased activity and levels of chitotriosidase and susceptibility to filarial infection (MF+ and CP; P = 0.013). The heterozygosity of CHIT1 gene was over-represented in the normal individuals (P = 0.034). The XX genotype of the promoter region in MBL2 was associated with susceptibility to filariasis (P = 0.0093). Since analysis for MBL-sufficient vs insufficient haplotypes was not informative, it is possible the MBL2 promoter association results from linkage disequilibrium with neighboring loci. We have identified two polymorphisms, CHIT1 and MBL2 that are associated with susceptibility to human filarial infection, findings that merit further follow-up in a larger study.

Animals↗

PubMed2001

Regulation of the immune response in lymphatic filariasis: perspectives on acute and chronic infection with Wuchereria bancrofti in South India.

Delineating the immune responses in lymphatic filariasis has been complicated not only by the rapidly expanding knowledge of new immunological mediators and effortors, but also by new methodologies (in particular, circulating filarial antigen detection) for defining and categorizing filarial-infected individuals. By using assays for circulating antigen in the sera collected as part of the many immunological studies performed on individuals in a Wuchereria bancrofti-endemic region of South India, we have attempted to explore the influence of patency on the antigen-driven proliferative and cytokine responses seen in peripheral blood mononuclear cells of individuals with varying clinical manifestations of lymphatic filarial infection. Moreover, we have provided perspectives on the differences between acute and chronic infection with W. bancrofti and suggested mechanisms that may underly the modulation of the immune response as patency occurs.

Acute Disease↗