PubMed Health⌕ Search

Biomedical subjects

S Anand

Publications and source records attributed to S Anand.

At least 19 recordsLinked to original sources
PubMed2006

Effect of DC/mDC iontophoresis and terpenes on transdermal permeation of methotrexate: in vitro study.

The systemic toxicity caused by methotrexate limits its use and transdermal delivery would be a possible alternative. Transdermal permeation of methotrexate loaded into polyacrylamide-based hydrogel patch, across mice skin was studied in vitro after pretreatment with terpenes and ethanol, alone or in combination with iontophoresis (DC/mDC). Polyacrylamide patches gave the maximum flux as compared to the copolymers of acrylamide and acrylic acid. Of the terpenes used, pure menthol showed maximum enhancement (38%), whereas pure limonene elicited a minimum of 9.9% enhancement. Binary combination of menthol and ethanol increased the permeation to 54.9%, which was further enhanced to 93.69% and 117% when used in combination with DC and square wave (mDC) iontophoresis, respectively. ATR-FTIR of the stratum corneum treated with terpenes showed a split in the asymmetric C-H stretching vibrations along with decrease in peak heights and areas of asymmetric, symmetric C-H stretching, C=O stretching and amide bands. A split in amide II band was observed with iontophoresis. ATR-FTIR studies suggest conformational changes in the lipid-protein domains thereby increasing permeation. Histopathological studies on treated skin samples, gave an insight about the anatomical changes brought by the application of various enhancers. Binary mixture of menthol and ethanol in combination with square wave gave best results.

Acrylic Resins↗
PubMed2006

Risk reduction counseling is associated with decreased HIV transmission-associated behaviors in high-risk Indian heterosexuals.

OBJECTIVE: To estimate the incidence of HIV and study the impact of risk-reduction counseling (RRC) in a cohort of people with high-risk behavior for HIV transmission in Chennai, India. DESIGN: Prospective cohort follow-up of 500 HIV-negative people (250 men and 250 women) at increased risk for HIV acquisition in Chennai, India for a maximum of 1 year was conducted. They received RRC at 0, 6, and 12 months. Generalized estimating equation methodology was used to determine the statistical significance of differences reported in behavior between baseline, 6 months, and 12 months. RESULTS: The overall HIV incidence in this cohort was 0.44 per 100 person-years (95% confidence interval: 0.05-1.60). In the course of the study, both male and female participants reported statistically significant decreases in the number of different sexual partners, the number of new partners, and the proportion of sexual encounters with nonprimary partners. Participants who had more than 3 different partners at baseline and/or exchanged money for sex in the 6 months before enrollment demonstrated the greatest reductions in the number of different sexual partners. CONCLUSIONS: Individualized sexual RRC seems to be a useful intervention to reduce risk-taking behavior among at-risk heterosexuals in India.

Adult↗
PubMed2006

Methotrexate used in combination with aminolaevulinic acid for photodynamic killing of prostate cancer cells.

Photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) to drive production of an intracellular photosensitiser, protoporphyrin IX (PpIX), is a promising cancer treatment. However, ALA-PDT is still suboptimal for thick or refractory tumours. Searching for new approaches, we tested a known inducer of cellular differentiation, methotrexate (MTX), in combination with ALA-PDT in LNCaP cells. Methotrexate alone promoted growth arrest, differentiation, and apoptosis. Methotrexate pretreatment (1 mg l(-1), 72 h) followed by ALA (0.3 mM, 4 h) resulted in a three-fold increase in intracellular PpIX, by biochemical and confocal analyses. After exposure to 512 nm light, killing was significantly enhanced in MTX-preconditioned cells. The reverse order of treatments, ALA-PDT followed by MTX, yielded no enhancement. Methotrexate caused a similar relative increase in PpIX, whether cells were incubated with ALA, methyl-ALA, or hexyl-ALA, arguing against a major effect upon ALA transport. Searching for an effect among porphyrin synthetic enzymes, we found that coproporphyrinogen oxidase (CPO) was increased three-fold by MTX at the mRNA and protein levels. Transfection of LNCaP cells with a CPO-expressing vector stimulated the accumulation of PpIX. Our data suggest that MTX, when used to modulate intracellular production of endogenous PpIX, may provide a new combination PDT approach for certain cancers.

Aminolevulinic Acid↗
PubMed2006

Removal of As(V) by Cu(II)-, Ni(II)-, or Co(II)-doped goethite samples.

The present study reports removal of As(V) by adsorption onto laboratory-prepared pure and Cu(II)-, Ni(II)-, and Co(II)-doped goethite samples. The X-ray diffraction patterns showed only goethite as the crystalline phase. Doping of ions in the goethite matrix resulted in shift of d-values. Various parameters chosen for adsorption were nature of adsorbent, percentage of doped cations in goethite matrix, contact time, solution pH, and percentage of adsorbate. It was observed that the pH(pzc) of the goethite surface depended on the nature and concentration of metal ions. The surface area as well as the loading capacity increased with the increase of dopant percentage in goethite matrix. A maximum loading capacity of 19.55 mg/g was observed for 2.7% Cu(II)-doped goethite. The adsorption kinetics for Ni(II), Co(II) and for undoped goethite attained a quasi-equilibrium state after 30 min with almost negligible adsorption beyond this time. In case of Cu(II)-doped goethite samples, the quasi-equilibrium state for As(V) adsorption was observed after 60 min. At each studied pH condition, it was observed that the percentage of adsorption of As(V) decreased in the order Cu(II)-doped goethite > or = Ni(II)-doped goethite > Co(II)-doped goethite > pure goethite. The adsorption followed: Langmuir isotherm, indicating monolayer formation.

Journal Article↗
PubMed2006

Comparison of auditory evoked potential parameters for predicting clinically anaesthetized state.

BACKGROUND: Most of the research efforts to monitor the depth of anaesthesia using the mid-latency auditory evoked potential (MLAEP) signal in humans are based on the detection of the amplitudes and latencies of the signal peaks. Attempts have also been made to combine different time-domain and frequency-domain parameters. A comparison of different parameters is required to identify those which best discriminate the awake state from the anaesthetized state. METHODS: Although the sensitivity of MLAEP signal peaks is appreciable in awake and light anaesthesia states, it is reduced considerably at the moderate anaesthesia level, rendering this method unsuitable for predicting the surgical stage of anaesthesia. To overcome this problem, a numerically derived quantity--the morphology index--was used which does not require location of the peaks of the signal, but, at the same time, reflects the changes in both the latency and amplitude of the peaks. AEPs were recorded in the hospital for 18 patients during various states, i.e. awake, induction, unconscious and after regaining consciousness from halothane anaesthesia. The peak latencies, amplitudes, morphology index and peak power frequency (PPF) were calculated. RESULTS: The sensitivity and specificity of PPF (89% and 95%, respectively) were found to be better than those for Pa and Nb peak amplitudes, their latencies and the morphology index. In addition, PPF showed minimum inter-patient variation. The mean value (standard deviation) of this parameter was 26.9 (0.67) during the awake state, decreased to 17.1 (1.2) during the anaesthetized state, and increased again to 26.1 (0.93) when the patients regained full consciousness. CONCLUSION: PPF is the best of the four studied MLAEP parameters for the clinical characterization of the anaesthetized state during surgery.

Acoustic Stimulation↗
PubMed2006

An enzyme-linked immunosorbent assay for monitoring of Aspergillus ochraceus growth in coffee powder, chilli powder and poultry feed.

AIMS: The work was carried out to develop an immunoassay for estimation of Aspergillus ochraceus biomass on solid substrate. METHODS AND RESULTS: An indirect noncompetitive enzyme-linked immunosorbent assay (ELISA) was developed for determination of fungal biomass in food commodities using antibody raised against A. ochraceus mycelial antigen. The sensitivity of the assay was linear in the range of 10-160 microg fungal biomass per millilitre extract of coffee (R(2)=0.989), poultry feed (R(2)=0.987) and chilli (R(2)=0.989). The growth of A. ochraceus in the food commodities like chilli, coffee beans and poultry feed, under the influence of two levels of moisture (20% and 30%) were monitored by the ELISA. The maximum fungal colonization was observed in poultry feed (9.8 and 11.8 mg g(-1)) followed by coffee beans (6.8 and 11.3 mg g(-1)) and chilli (5.1 and 6.3 mg g(-1)) at 20% and 30% moisture after 20 days of incubation. Similarly the fungus produced maximum ochratoxin A in poultry feed (25 and 120 microg g(-1)) followed by coffee beans (8 and 24 microg g(-1)) and chilli (0.2 and 0.45 microg g(-1)) at 20% and 30% moisture after 20 days of incubation. CONCLUSIONS: The method can be used for quantitative estimation of fungal biomass and comparison of fungal colonization in food substrates varying in composition. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be adapted for studying the fungal colonization in different solid substrates under different culture condition. The method is sensitive to mould colonization of >or=0.02% (w/w) and can be used for early detection of specific fungal infestation in food commodities.

Analysis of Variance↗
PubMed2005

Tuberculosis: an under-diagnosed aetiological agent in uveitis with an effective treatment.

PURPOSE: To highlight the diversity of clinical presentations with tubercular uveitis in a nonendemic setting, and discuss the diagnostic approach and an effective treatment. METHOD: Descriptive case series. RESULTS: A total of 12 cases of varied presentations of tubercular uveitis diagnosed over a period of 1 year of which six cases are described in detail. Presentations included choroidal tuberculomas, multifocal choroiditis, recurrent granulomatous uveitis, panuveitis with cystoid macular oedema, and serpiginous choroiditis. All cases had a chronic or recurrent course and responded very well to antitubercular treatment. Diagnosis was mainly assisted by positive tuberculin testing. CONCLUSION: A high index of suspicion helps diagnose ocular tuberculosis in areas of low prevalence of the disease. It forms part of the differential diagnosis of any chronic or recurrent uveitis, especially in an at-risk patient. Antitubercular treatment seems highly effective.

Adolescent↗
PubMed2005

Ethnic differences in the relationships between obesity and glucose-metabolic abnormalities: a cross-sectional population-based study.

OBJECTIVES: To evaluate whether body mass index (BMI) and other anthropometric indices of visceral obesity vary by ethnic group in their distribution and their relationship to metabolic abnormalities. DESIGN: Cross-sectional study. PARTICIPANTS: Canadian men and women, aged 35-75 years, of South Asian (n=342), Chinese (n=317), European (n=326) and Aboriginal (n=301) descent were recruited using stratified random sampling. PRIMARY MEASURES: Anthropometric indices (BMI, waist to hip ratio (WHR) and waist circumference (WC)), metabolic markers (fasting glucose, HbA1c, the ratio of total cholesterol/HDL) and clinical markers (systolic blood pressure) were assessed. RESULTS: In subjects with BMI<30 kg/m2, the mean marker levels in people with elevated WC (>88 cm in women, >102 cm in men) vs people with normal WC were 6.16 vs 5.34 mmol/l for fasting glucose, 6.05 vs 5.66% for HbA1c and 5.46 vs 4.68 for the ratio of total cholesterol to HDL (P<0.001 in each case). At nearly every given level of BMI, non-European ethnic groups displayed significantly higher marker levels than Europeans. For example, for a given BMI, age and sex, the difference between European and non-European groups in HbA1c levels was 0.53% (95% confidence interval (CI): 0.37-0.69) for South Asians, 0.37% (95% CI: 0.2-0.54) for Chinese and 0.95% (95% CI: 0.78-1.12) for Aboriginal People. CONCLUSIONS: Uniform cut-points for the classification of obesity using BMI, WHR or WC result in marked variation in the levels of glucose-metabolic abnormalities between ethnic groups. Existing action thresholds for these anthropometric indices do not apply to non-European ethnic groups and warrant revision.

Adult↗
PubMed2005

A multivariate study of three body measurements of different states of India.

Considerable attempts have been made to study the changes in three important body measurements (viz. body height, body weight and chest circumference) in young healthy males between different states of India using univariate statistical analysis in which body measurements are assumed to be independent of each other. Actually these body measurements are correlated with each other and thus the assumption of independence is violated in univariate statistical analysis. Hence the results obtained by univariate statistical analysis may be misleading. An attempt has, therefore, been made in the present study to apply multivariate statistical analysis in order to have an idea about the simultaneous changes in these three correlated measurements between different states of India in healthy Indian males of age ranging from 16-21 years. It has been concluded that significant changes take place in these three body measurements simultaneously of young healthy males of 16-21 years of age between different states of India.

Adolescent↗
PubMed2005

An approach to addressing ethical issues in a community-based risk assessment for HIV: a case from Chennai, India.

Community-based assessment of HIV prevalence and behavioural risk factors is the basis for deciding priorities of prevention and care programmes. Here, upholding the human rights of participants in assessment is of utmost importance. The objective of the paper was to describe the process of implementation of an epidemiological survey to assess HIV-related behavioural and biological factors in Chennai city in South India and to suggest an ethical framework for conducting similar assessment activities in developing-country settings. A survey was conducted with participation from residents (n=1,659) of low-income urban communities (slums) as part of a community-based HIV/STD-prevention trial. Administration of the survey was preceded by extensive community contact and household visits to inform community members about the trial and assessment activities. Formative research further strengthened rapport with community, highlighted community concerns, and identified HIV-related risk behaviours that informed questionnaire design. The process of obtaining informed consent began before assessment activities and provided an opportunity for individuals to discuss participation with their families and friends. Privacy during assessment, comprehensive follow-up care for those who tested positive for HIV/STDs, such as nutritional and prevention counselling, referral services for opportunistic infections, and antenatal-care options for pregnant women increased trust and credibility of the project. The sustained availability of trial staff to facilitate access to resources to address non-HIV/STD-related felt-needs further strengthened participation of the community members. These resources included liaison services with local government to obtain public services, such as water and electricity and resources, to address concerns, such as alcohol abuse and domestic violence. Based on this experience, an ethical framework is suggested for conducting HIV epidemiological risk assessment in developing countries. This framework discusses the role of community participation, transparent and comprehensive informed consent, timely dissemination of results, and access to follow-up care for those living with HIV/STDs.

Adolescent↗
PubMed2004

Perceptual learning of line orientation modifies the effects of transcranial magnetic stimulation of visual cortex.

Perceptual learning may be accompanied by physiological changes in early visual cortex. We used transcranial magnetic stimulation (TMS) to test the postulate that perceptual learning of a visual task initially performed at 60-65% accuracy strengthens visual processing in early visual cortex. Single pulse TMS was delivered to human occipital cortex at time delays of 70-154 ms after the onset of an odd-element, line orientation discrimination task. When TMS was delivered at a delay of 84 ms or later the accuracy of visual discrimination was transiently degraded in ten subjects. As visual performance in control trials without TMS improved with training, the absolute magnitude of TMS suppression of performance decreased in parallel. This result occurred both when TMS was delivered to broad areas of occipital cortex and when TMS was optimally delivered to early occipital cortex. No change in TMS suppression was observed when three new subjects were given feedback during an odd-element task that did not require substantial perceptual learning. Thus, perceptual learning improved visual performance and reduced TMS suppression of early visual cortex in parallel.

Adolescent↗
PubMed2004

Negative refraction at infrared wavelengths in a two-dimensional photonic crystal.

We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area.

Journal Article↗
PubMed2004

High-bandwidth transmission of an efficient photonic-crystal mode converter.

We have investigated both theoretically and experimentally the spectral behavior and the transmission and reflection performance of a photonic-crystal (PhC) mode converter upon an InP substrate. This taper exhibits 70% transmission efficiency on an 80-nm bandwidth when it couples a ridge access guide to a strongly confined single-missing-row PhC guide. Such a taper design included in a PhC bend contributes a large benefit to the overall transmission budget of the PhC-based link.

Journal Article↗
PubMed2004

Inactivation of the cytotoxic activity of repin, a sesquiterpene lactone from Centaurea repens.

Prolonged ingestion of Yellow Starthistle (Centaurea solstitialis) and Russian Knapweed (Centaurea repens) by horses has been shown to result in a fatal neurodegenerative disorder called equine nigropallidal encephalomalacia (ENE). Bioassay-guided fractionation of extracts from Centaurea species using the PC12 cell line have led to the identification of one of several putative agents, which may contribute to ENE, namely, the sesquiterpene lactone (SQL) repin (1), previously linked to ENE due to its abundance in C. repens. To characterize the molecular basis of repin-induced neurotoxicity, the present study was designed to identify reactive functional groups that may contribute overall to its toxicity. The reaction of repin (1) with glutathione (GSH) led to the exclusive addition of GSH to the alpha-methylenebutyrolactone affording a GSH conjugate (3b) that lacked toxicity in the PC12 cell assay, while selective reduction of the alpha-methylenebutyrolactone double bond of 1 also resulted in an analogue (2) that was devoid of toxicity relative to the parent compound. Unlike repin, analogue 2 failed to decrease cellular dopamine levels in PC12 cells, further substantiating the requirement of the alpha-methylenebutyrolactone group. Results from this study are suggestive that GSH depletion by the SQL repin may be a primary event in the etiology of ENE, increasing the susceptibility to oxidative damage.

Animals↗
PubMed2004

Endovascular management of intracranial pial arterio-venous fistulas.

From 1996-2002 we treated 5 consecutive cases of pial fistula. There were 3 patients with a single hole-single channel pial fistula and two patients had a complex pial fistula. Three patients presented with intracerebral hematoma and had a focal neurological deficit. One patient presented with history of seizures and 1 patient had headache. The results of the treatment were analyzed both clinically and angiographically. The follow-up period ranged from 6 months to 6 years. All fistulas were treated with concentrated glue. The glue cast included the distal part of the feeding artery, A-V connection and the proximal part of the vein. Post-embolisation angiography showed complete occlusion of two single-hole fistulas and one complex pial A-V fistula and near total occlusion of one single-hole and one complex pial A-V fistula. Four patients had excellent clinical outcome. One patient with single-hole fistula had a hemorrhagic venous infarct resulting in transient hemiparesis.

Adolescent↗