Search PubMed⌕ Search

Biomedical subjects

R Balasubramanian

Publications and source records attributed to R Balasubramanian.

At least 19 recordsLinked to original sources
PubMed2006

Contrasting reactive oxygen species and transition metal concentrations in combustion aerosols.

The presence of reactive oxygen species (ROS) and 10 transition metals (Ag, Cd, Co, Cu, Fe, Mn, Ni, Ti, V and Zn) in both the acid-soluble and water-soluble fractions of fine particles of combustion origin were determined. ROS was analyzed using the dichlorofluorescin fluorescence technique. Particles emitted from on-road vehicles, gas cooking, incense burning, and cigarette smoke were characterized along with those in the background air of outdoor and indoor environments. In addition, this study evaluated the possible relationships between ROS and individual transition metals. It is found that cigarette smoke which had the highest concentration of metals also contained the highest concentration of ROS. Regression analysis performed showed that water-soluble metals including Cd, Co, Cu, Fe, Mn, and Ni showed better correlation with ROS concentration as compared to acid-soluble (total) metals. The findings demonstrated that water-soluble metals could be one of the species influencing ROS formation in ambient air.

Air Pollutants↗
PubMed2006

Evaluation of the marine algae Ulva fasciata and Sargassum sp. for the biosorption of Cu(II) from aqueous solutions.

In this study, the adsorption properties of two different marine algae (Ulva fasciata (green algae) and Sargassum sp. (brown algae)) were investigated. Equilibrium isotherms and kinetics were studied to evaluate the relative ability of the two algae to sequester Cu(II) from aqueous solutions. The maximum biosorption capacity obtained was 73.5 mg g(-1) for U. fasciata and 72.5 mg g(-1) for Sargassum sp. at a solution pH of 5.5 +/- 0.5. A significant fraction of the total copper(II) uptake was achieved within 30 min. The copper(II) uptake by the biosorbents was best described by pseudo-second-order rate model.

Adsorption↗
PubMed2006

Risk assessment of exposure to indoor aerosols associated with Chinese cooking.

Cooking is an important source of indoor aerosols in residential homes and buildings with non-smokers, and thus has public health implications. However, limited information is currently available in the published literature on the physical and chemical characteristics of aerosols produced by gas cooking. Consequently, a comprehensive study was carried out to investigate the physical (number and mass concentrations and size distributions) and chemical (metals) properties in a typical Chinese food stall in Singapore where stir-frying in a wok is the most common cooking method using gas stove. To assess the contribution of cooking activities to indoor particle concentrations, aerosol measurements were performed in two distinct time periods, i.e., during cooking and non-cooking hours. The average mass concentrations of fine particles (PM(2.5)) and metals increased by a factor of 12 and 11, respectively, from 26.7 and 1.5microgm(-3) during non-cooking hours to 312.4 and 15.6microgm(-3) during cooking hours. The average number concentration was also elevated by a factor of 85, from 9.1x10(3)cm(-3) during non-cooking hours to 7.7x10(5)cm(-3) during cooking hours. Real-time particle measurements showed that about 80% of the particles associated with cooking are ultrafine particles in terms of particle counts. To evaluate the potential health threat due to inhalation of air pollutants released from gas cooking, the health risk estimates based on exposure and dose-response assessments of metals were calculated for a maximally exposed individual. The findings indicate that the indoor air quality existing at the food stall may pose adverse health effects over long-term exposure to cooking emissions.

Aerosols↗
PubMed2006

Elderly lady with ascites.

An elderly lady with amylase-rich ascites is presented, whose isoenzyme estimation revealed salivary type amylase. Tumour hyperamylasemia is an important group among the nonpancreatic causes of elevated amylase.

Amylases↗
PubMed2006

A rural public-private partnership model in tuberculosis control in south India.

SETTING: A rural tuberculosis (TB) unit in South India, 2001-2003. OBJECTIVE: To evaluate a rural public-private partnership model (PPPM) within the TB control programme (RNTCP). DESIGN: All of the private practitioners trained in modern medicine (PPs, n = 52) and the private laboratories (PLs, n = 13) in the area were listed. The PPs underwent training about the RNTCP, and PL staff were trained in sputum microscopy. PPPM included referral of TB suspects to the smear microscopy centres (government or PLs) for diagnosis and treatment of patients as per RNTCP guidelines. Patients were back-referred to the PPs. The directly observed treatment providers and centres were chosen by the PPs in consultation with their patients. The case detection rate, cure rate and profile of patients referred by the PPs were compared with those of self-reported patients. RESULTS: Of 489 TB suspects referred by the PPs, 24% were smear-positive compared to 10% of 15 278 self-reported patients (P < 0.001). Of 319 referred to PLs, 7% were smear-positive. The annual average case detection rate increased from 66 to 75 per 100 000 population. The cure rates of patients referred by the PPs were comparable to those of self-reported patients. CONCLUSIONS: This rural PPPM is effective and does not require additional staff or any direct financial incentives.

Adult↗
PubMed2005

Upper limits on a stochastic background of gravitational waves.

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of omega0 < 8.4 x 10(-4) in the 69-156 Hz band is approximately 10(5) times lower than the previous result in this frequency range.

Journal Article↗
PubMed2005

Limits on gravitational-wave emission from selected pulsars using LIGO data.

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Journal Article↗
PubMed2005

Evaluation of a microwave-assisted extraction technique for determination of water-soluble inorganic species in urban airborne particulate matter.

A simple and rapid microwave-assisted extraction (MAE) technique has been developed for the determination of water-soluble inorganic species (cations: Na+, NH4+, K+, Ca2+ and Mg2+ and anions: F-, Cl-, NO3-, PO4(3-) and SO4(2-)) in airborne particulate matter. The analytes were extracted under different treatment conditions such as microwave power and extraction time. They were quantified using ion chromatography. The observed concentrations and recovery yields obtained under different conditions were compared. The results of a comparison between this MAE and sonication using NIST SRM 1648 are also given in this paper. The optimized MAE technique gave results in good agreement with the values obtained by the sonication. For some ions, for example Mg2+ and K+, recovery was low with both techniques. The results demonstrated that the optimized MAE is fast and efficient compared with conventional ultrasonic extraction. Urban airborne particles were collected and subjected to the MAE followed by the IC analysis to determine the relative proportions of different water-soluble inorganic species. These results are briefly discussed.

Journal Article↗
PubMed2005

Perceptions of tuberculosis patients about their physical, mental and social well-being: a field report from south India.

Tuberculosis (TB) often leaves its impact physically, socially and mentally on patients. The goal of current tuberculosis services is microbiological cure of tuberculosis. Understanding patients' perceptions about TB will enable better design of a client-oriented comprehensive programme for tuberculosis. We interviewed patients registered for treatment during July-December 2000 in government health facilities of two tuberculosis units of south India. Data on perceptions of their illness before the onset of illness and during the treatment period were collected, using a modified SF36 questionnaire. Health status was measured for the following: physical functioning, social role limitations due to physical and emotional problems (stigma), mental health, energy vitality, pain and general health perceptions. Of 980 patients registered, 610 (206 females) cured or treatment completed patients were interviewed at two time points. The reaction of patients to the disclosure of the diagnosis was worry (50%) and suicidal thoughts (9%). 'Good health status' was perceived initially in less than 7% of patients, and compared to the status at the onset of illness, there was significant improvement after treatment (more than 78% trend chi square p<0.05). Despite microbiological cure, 47% of patients continued to have respiratory symptoms; this was significantly higher among patients who had delayed taking action for more than 3 months. Only 54% of patients perceived 'happy mental status' at the end of treatment, and there was no change in social stigma in both men and women. Tuberculosis control programmes should address issues such as continued respiratory symptoms, persistence of stigma, and poor emotional quality of life of patients with tuberculosis, even after they are cured. As well, providing social support for the needy, timely counseling and health education of patients, which will alleviate mental and social sufferings of patients, should be considered.

Activities of Daily Living↗
PubMed2004

Characterization and source identification of airborne trace metals in Singapore.

Airborne particulate trace metals have important health implications. As a consequence, their concentrations are increasingly monitored in many urban locations worldwide. In this study, fine atmospheric particles (PM(2.5)) were collected in Singapore over a period of 83 consecutive days during 2000, and analysed to determine the concentration of trace elements using ICP-MS. Altogether, eighteen airborne trace metals were quantified: Al, Ag, Ba, Cd, Cr, Co, Cu, Fe, Ga, Li, Mn, Ni, Pb, Sr, Zn, V, Si, and Ti. While Li was the least abundant trace metal with a mean concentration of 0.2 ng m(-3), Zn showed the maximum mean concentration of 279.1 ng m(-3). Calculation of enrichment factors indicated that the elements Pb, Zn, Cd, V, Ni, Cr, and Cu were enriched by factors of 30 to 5000 relative to their natural abundance in crustal soil. The extent of metal pollution in the study area was assessed by comparing the measured concentrations to those reported in the literature for a selected number of urban sites in other parts of the world. Factor analysis was used to identify the major sources affecting particulate air pollution in Singapore. The sources that contribute to the loading of trace metal-bearing aerosols in the Singapore urban atmosphere include fuel oil-fired power plants, metal processing industry, land reclamation and construction activities, municipal solid waste incinerators, and traffic emissions.

Acids↗
PubMed2004

Gender disparities in tuberculosis: report from a rural DOTS programme in south India.

SETTING: Tiruvallur District, south India. OBJECTIVES: To examine gender differences in tuberculosis among adults aged >14 years with respect to infection and disease prevalence, health care service access, care seeking behaviour, diagnostic delay, convenience of directly observed treatment (DOT), stigma and treatment adherence. METHODS: Data were collected from 1) community survey, 2) self-referred out-patients seeking care at governmental primary health institutions (PHIs), 3) tuberculosis suspects referred for sputum microscopy at PHIs, and 4) tuberculosis patients notified under DOTS. Community survey results were compared with those for patients notified at PHIs. RESULTS: In the community, 66% of males and 57% of females had tuberculosis infection. The prevalence of smear-positive tuberculosis was 568 and 87/100,000, respectively, among males and females. Fewer males than females attended PHIs (68 men for every 100 women). Females constituted 13% of all smear-positive patients detected in the community survey, and 20% of those detected at PHIs (P < 0.05). The probability of notification decreased significantly with age among both males and females. Significantly more females than males felt inhibited discussing their illness with family (21% vs. 14%) and needed to be accompanied for DOT (11% vs. 6%). Males had twice the risk of treatment default than females (19% vs. 8%; P < 0.01). CONCLUSIONS: Despite facing greater stigma and inconvenience, women were more likely than men to access health services, be notified under DOTS and adhere to treatment. Men and elderly patients need additional support to access diagnostic and DOT services.

Adolescent↗
PubMed2004

Near-fatal amlodipine poisoning.

Amlodipine poisoning is very rare and only few cases have been reported in English literature. We report here a case of severe amlodipine poisoning with non-cardiogenic pulmonary edema.

Adult↗
PubMed2003

Chemical characterization of rainwater at Singapore.

A short term study of the chemical composition of rainwater was carried out from November 1999 to October 2000 in Singapore. The rainwater was typically acidic with a mean pH of 4.2. Sulfate was the most abundant ion and comparable to the results reported for other industrialized regions. The concentrations of major ions (NH(4)(+), Ca(2+), K(+), Na(+), Mg(2+), SO(4)(2+), NO(3)(2-), Cl(-), HCOO(-), CH(3)COO(-)) varied monthly. Results show that local meteorological conditions influence the chemical compositions to a significant extent. The pollutants in rainwater were derived from long range and local (industry and traffic) sources.

Acid Rain↗
PubMed2003

Are community surveys to detect tuberculosis in high prevalence areas useful? Results of a comparative study from Tiruvallur District, South India.

BACKGROUND: In Tiruvallur District, South India, tuberculosis cases are detected at health facilities (HF) as part of a DOTS programme, and by screening adults through community survey (CS) as part of ongoing epidemiological research. OBJECTIVE: To compare socio-demographic, clinical and bacteriological characteristics and treatment outcomes of all patients detected at HF with those of all patients detected by CS during a 12-month period. RESULTS: Of 32,663 adults surveyed, 100 had smear-positive and 116 had smear-negative tuberculosis; of 65 smear-positive patients who began treatment, 44 were cured. Compared to HF patients, CS patients were significantly more likely to be older (AOR = 1.9), male (AOR = 2.7), non-literate (AOR = 1.7), and living in poor quality housing (AOR = 2.0), and were less likely to have cough >3 weeks (AOR = 3.4) or smear-positive tuberculosis (AOR = 4.2). Of 61 new smear-positive CS patients, 40 reported chest symptoms; of these, 32 (80%) had already consulted a health-care provider, but remained undiagnosed. CONCLUSIONS: The community survey was of little value in tuberculosis case detection even in this high-prevalence setting. Patients identified by the survey were less symptomatic and less infectious, and less than half were cured. Diagnostic services should be made more accessible to the elderly, the non-literate and men.

Adult↗
PubMed2002

Private pharmacies in tuberculosis control--a neglected link.

In most settings in India, private pharmacies dispense prescriptions for anti-tuberculosis drugs made out by private practitioners. In a cross-sectional study, we assessed the dispensing practices for tuberculosis and knowledge about the national tuberculosis programme of 300 pharmacies. In all, 2800 prescriptions were dispensed monthly by the pharmacies. Doctors' prescriptions were for durations of several months, but half of the patients bought drugs one dose at a time for self-administration. This practice might promote drug resistance. Although 95% of pharmacists were not aware of the existence of the tuberculosis programme, the majority (97%) were willing to learn and contribute towards tuberculosis control. The need and the potential of private pharmacies for participation in tuberculosis control are highlighted.

Antitubercular Agents↗
PubMed2001

Design and synthesis of novel chiral dendritic species derived from bile acids.

Bile acids have been used for the first time as the building block for the construction of dendritic units. Orthogonally functionalized 7-deoxycholic and cholic acid derivatives were synthesized. The construction of a bile acid heptamer, a nonamer, and a decamer using the convergent strategy are described in detail. Chromatographic, spectral, and optical properties of these molecules have been investigated. Molecular modeling suggests that these molecules have globular shapes with nanometric dimensions.

Bile Acids and Salts↗
PubMed2001

Estimation of the timing of perinatal transmission of HIV.

Knowledge of the timing of perinatal transmission of HIV would be valuable for the determination and evaluation of preventive treatments and would shed light on the mechanism of transmission. Estimation of the distribution of the time of perinatal transmission is difficult, however, because tests of infection status can only be undertaken after birth. DNA and RNA polymerase chain reaction (PCR) assays and HIV culture have been the most commonly used diagnostic tests for perinatal HIV infection. Such tests have high sensitivity and specificity, except when they are given shortly after infection. In this paper we use the time-dependent sensitivity of these diagnostic tests to make nonparametric and semiparametric inferences about the distribution of the time of perinatal HIV transmission as well as the cumulative probability of perinatal transmission. The methods are illustrated with data from a clinical trial conducted by the AIDS Clinical Trials group.

Anti-HIV Agents↗