Comparative efficacy of different reference drugs on trinitrobenzenesulfonic acid-induced ulcerative colitis in the rat model.

Crohn’s disease and Ulcerative colitis were chronic inflammatory disorders of the bowel categorized as inflammatory bowel diseases. Trinitrobenzene sulfonic acid (TNBS)-induced colitis was one of the most common methods for studying inflammatory bowel disease in animal models. Several factors may, however, affect its reproducibility, rate of animal mortality, and macroscopic and histopathological outcomes.The current study was undertaken with the objective to validate the main contributing factors to this method and compare the effects of different reference drugs upon better amelioration of trinitrobenzenesulfonic acid (TNBS) induced colitis. With the above objectives, ulcerative colitis was induced by intrarectal administration of TNBS in male Wistar rats at a dose rate of 20 mg in 0.5 mL of ethanol per animal for all groups except the negative control group, which received 0.5 mL of normal saline. Different reference drugs like dexamethasone (1 mg/kg, intraperitoneally (i.p.) and 2 mg/kg, orally (p.o.)), hydrocortisone acetate (20 mg/kg, i.p.; 20 mg/kg, enema) and sulfasalazine 500mg/kg ,p.o.were administered daily once from Day 3 to 9 except the negative and positive controls which received normal saline at the rate of 10 mL/kg body weight. All the animals were sacrificed on Day 10; the colons were excised and the colon morphology and net weight of the colon segment were graded and measured, respectively. The intestinal damage had improved significantly in the experiment groups that received different reference drugs which is comparable with sulfasalazine treated group. The experimental observations, gross pathology of intestinal lesions and statistical analysis reveals no significant difference among the different reference drugs treated groups.

Effect of salinity on the predatory performance of Diplonychus rusticus (Fabricius).

Predatory efficiency of Diplonychus rusticus (Fabricius) was recorded at different prey density with different salinity ranges. When the salinity level (ppt) was increased, the predation rate of the bug decreased. Fifth nymphal stage showed higher predation in the 2, 4 and 6 ppt levels of salinityin both 1 hr and 24 hr period of exposure at prey densities 50, 100, 150 and 200. At prey density 150, adult bugs killed more prey in the 2 ppt level of salinity in both lhr and 24 hr treatments.

Long term follow up of HIV-infected patients with tuberculosis treated with 6-month intermittent short course chemotherapy.

BACKGROUND: Tuberculosis occurs in 60%-70% of HIV-positive persons in India. The outcome of HIV-positive patients treated with 6-month intermittent short course antituberculosis regimens in India is not well described. METHODS: This was a prospective observational feasibility study of 71 patients with HIV and tuberculosis who were treated with category I regimen of the Revised National Tuberculosis Control Programme (ethambutol, isoniazid, rifampicin and pyrazinamide thrice weekly for the initial 2 months followed by rifampicin and isoniazid thrice weekly for the next 4 months). Sputum was examined by smear and culture for Mycobacterium tuberculosis every month up to 24 months. Chest X-ray, CD4 cell count and viral load were done prior to and at the end of treatment. None of the patients received antiretroviral therapy. RESULTS: We present here the treatment response of patients with sputum culture-positive pulmonary tuberculosis to category I regimen. By efficacy analysis, among 43 patients treated with category I regimen, sputum smear conversion was observed in 79% and culture conversion in 82% at the second month. A favourable response was seen in 72% of patients. The mean (SD) CD4% fell from 12.6 (5.9) to 8.9 (4.9) (p < 0.001) with no significant change in mean (SD) CD4 cell count (169 [126] to 174 [158]; ns) at the end of treatment. Viral load change from 1.8 x 10(5) at baseline to 1.3 x 10(5) at the end of treatment was not statistically significant. Thirty-one patients, who completed the full course of treatment, were declared cured and were followed up for 24 months. Twelve had recurrent tuberculosis (39%); 16 of 43 (37%) patients had died by the end of 24 months, two-thirds due to causes other than tuberculosis. CONCLUSION: Though the early bacteriological response to intermittent short course antituberculosis regimen was satisfactory, the overall outcome was adversely affected by the high mortality (during and after completion of treatment) and recurrence rate among HIV-infected patients with tuberculosis. Immune status deteriorated in spite of antituberculosis treatment, highlighting the need for antiretroviral treatment in addition to antituberculosis treatment to improve the long term outcome. The results of this pilot study need to be confirmed by larger studies.

A pilot study on willingness to participate in future preventive HIV vaccine trials.

BACKGROUND & OBJECTIVES: In India, phase-I human clinical trials for a preventive HIV vaccine are being conducted at Pune and Chennai Centres. In order to find out the willingness of populations at risk to participate in future preventive HIV vaccine trials (HIVVTs) and to assess the factors that enhance or deter them from participation, a study was conducted at Chennai and Madurai in Tamil Nadu. METHODS: This cross-sectional study was conducted among transport workers, people attending sexually transmitted infection clinics, injection drug users, men having sex with men, women in sex industry and a representative sample of monogamous married women, by employing measurement scales. A structured questionnaire on knowledge and attitudes about the HIV vaccine was used to measure the participants' knowledge and attitudes about HIV vaccine and HIVVTs. RESULTS: Of the 112 participants, 67 (60%) were men. Mean age of the respondents was 32 yr; 68 per cent were high school educated. Majority of respondents were willing to participate in a future HIVVT and the reasons were altruism, protection from HIV, and support for the researchers. Major concerns were vaccine efficacy, side effects of the vaccine and the impact of a HIV vaccine on the participants' lives. Majority (85%) agreed that sex without condom would not be safe despite the availability of an HIV vaccine. INTERPRETATION & CONCLUSION: It is likely that high-risk volunteers will be willing to enroll in HIVVTs. Barriers and concerns should be dealt with carefully by providing correct information. Also there is a need for more education to ensure participants' understanding of key concepts of HIV vaccine trial.

A comprehensive back-calculation framework for estimation and prediction of HIV/AIDS in India.

HIV incubation period is the random time between the HIV-infection and the onset of clinical AIDS. Distribution of this non-negative random variable is known as HIV incubation period distribution. The Back-calculation method reconstructs the past pattern of HIV infection and predicts the future number of AIDS cases with the present infection status. It depends on three important factors: incubation distribution, incidence curve and observed number of AIDS cases over time. This method is very popular and requires less information and assumptions. Lack of information about incubation distribution, the effect of intervention therapy on incubation period, and errors in reported AIDS incidence leads to uncertainties associated with this method. The incubation distribution is assumed to be exactly known in back-calculation methodology. Incubation period of HIV is very long and highly variable within and between cohorts. The current prevalence of HIV-infection and the corresponding pattern of incidence from the beginning of the epidemic to the present time are mainly estimated by means of back-calculation method. It calculates the most likely temporal distribution of infected individuals compatible with the number of observed AIDS cases starting from the suitable estimate of the incubation period, derived from the available data. Most of the projections formulated the problem of estimation of future AIDS cases as estimation of parameters in multinomial likelihood with unknown sample size by EM algorithm. In this paper the various approaches for modeling the incubation distribution are compared using real and simulated data under various infection density distributions. The projected minimum AIDS cases in India based on the reported data for the years 2003, 2004, 2005 and 2006 are around 27000, 44000, 70000 and 113000 respectively. The corresponding figures based on the adjusted data are around 67000,100000,150000 and 230000 respectively.

Standardization of the method for estimation of ethambutol in pharmaceutical preparations and biological fluid.

A simple column chromatographic method for determination of ethambutol (EMB) in pharmaceutical preparations containing EMB in combination with other anti-TB drugs is presented. The method involved extraction of EMB into an organic solvent, followed by basification and column chromatographic separation on Amberlite CG 50 (100-200 mesh) and elution with suitable eluants and estimation at a wavelength of 270 nm. The assay was linear from 25 to 400 microg/ml. The relative standard deviations of intra and inter day assays were lower than 5%. Ethambutol was recovered from human urine quantitatively and stable for a period of at least one week in urine stored at -20 degrees C.

Bioavailability of rifampicin following concomitant administration of ethambutol or isoniazid or pyrazinamide or a combination of the three drugs.

BACKGROUND & OBJECTIVES: Poor bioavailability of rifampicin (R) in combination with other anti-tuberculosis drugs such as isoniazid (H), pyrazinamide (Z), and ethambutol (E) is a subject of much concern for the last few decades. This could be due to an interaction between R and other drugs. An investigation was therefore undertaken to examine the bioavailability of R in the presence of H, Z and E or a combination of the three drugs. METHODS: The study included eight healthy volunteers, each being investigated on four occasions at weekly intervals once with R alone and with three of the four combinations on the three remaining occasions. A partially balanced incomplete block design was employed and the allocation of R or the drug combinations was random. Plasma concentrations of R at intervals up to 12 h were determined by microbiological assay using Staphylococcus aureus as the test organism. The proportion (%) dose of R as R plus desacetyl R (DR) in urine excreted over the periods 0-8 and 8-12 h was also determined. Bioavailability was expressed as an index (BI) of area under time concentration curve (AUC) calculated from the plasma concentrations or proportion of dose of R excreted as R plus DR in urine with the combinations to that with R alone. RESULTS: The bioavailability indices based on AUC were 0.96 with RE, 0.76 with RH, 1.08 with RZ and 0.65 with REHZ. The indices based on urine estimations (0-8 h) were similar, the values being 0.94, 0.84, 0.94 and 0.75, respectively. A second investigation revealed that the decrease of bioavailability of R with H was not due to the excipients present in H tablets. INTERPRETATION & CONCLUSION: Isoniazid alone or in combination with E and Z reduces the bioavailability of R. Urinary excretion data offer a simple and non invasive method for the assessment of bioavailability of R.

Prevalence of asthma in urban and rural children in Tamil Nadu.

BACKGROUND: There are very few community-based studies on the prevalence of asthma in Indian children. We aimed to estimate the prevalence of asthma in children under 12 years of age and to study possible differences in the prevalence of childhood asthma in urban and rural areas of Tamil Nadu. METHODS: A total of 584 children from Chennai and 271 children from 25 villages around Chennai formed the urban and rural groups, respectively. From November 1999 to February 2000, data were collected using a simplified version of the ISAAC questionnaire, which was administered by trained students. Symptoms suggestive of asthma or hyperreactive airways disease in children under 12 years of age were recorded from the selected urban and rural populations by questioning the parents. The results were analysed separately for children 0-5 and 6-12 years of age. RESULTS: Of the 855 children studied, the overall prevalence of breathing difficulty (including asthma) was 18% and the prevalence of 'diagnosed' asthma was 5%. Twenty-two per cent of urban and 9% of rural children 6-12 years of age reported breathing difficulty 'at any time in the past' (p < 0.01). A significantly higher proportion of 6-12-year-old urban children also reported nocturnal drycough (28.4% v. 18.7%, p < 0.05). Urban children reported recent wheeze more often than rural children (92% v. 77%, p = 0.01). CONCLUSIONS: Symptoms suggestive of asthma were present in 18% of children under 12 years of age. Though the prevalence of diagnosed childhood asthma was about 5% in both urban and rural areas, the prevalence of 'breathing difficulty' and nocturnal cough was significantly higher among urban children in the age group of 6-12 years. Children living in urban areas also reported 'recent wheeze' more often than rural children. Our data suggest that the actual prevalence of asthma and other 'wheezy' illnesses may be higher than that previously documented. Further studies are needed to confirm the difference in prevalence between urban and rural children and also to identify possible causes that could account for the higher urban prevalence of asthma in Tamil Nadu.

Pulmonary function in normal south Indian children aged 7 to 19 years.

There are only a few studies that have established reference standards for pulmonary function of Indian children. Reference standards for pulmonary function that are reported for Indian children are mainly from northern and western parts of the country and there is a paucity of data on pulmonary function in normal South Indian children. Therefore, pulmonary function tests (spirometry and maximal expiratory flow rates) were carried out in 469 South Indian healthy children (246 boys and 223 girls) between 7-19 years of age to derive regression equations to predict pulmonary function. The correlations of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were, in general highest with height followed by weight and age. Peak expiratory flow rate (PEFR), forced mid-expiratory flow (FMF) and forced expiratory flow rates at 25%, 50% and 75% of FVC (FEF25% FVC, FEF50%FVC and FEF75%FVC) were also significantly correlated with physical characteristics (age, height and weight). With a view to find out regression equations to predict spirometric functions based on physical characteristics (age, height and/or weight), the functions were regressed over all possible combinations of regressor variables, i.e. age, height and weight separately for boys and girls. The height influences the prediction equation in males to a great extent, whereas age and weight had greater influence in girls. Regression equations were derived for boys and girls for predicting normal pulmonary functions for children in South India. The pulmonary function measurements in South Indian children were similar to those reported for subjects from Western India and lower than those reported for Caucasians.

Bioluminescence assay of adenosine triphosphate in drug susceptibility testing of Mycobacterium tuberculosis.

Twenty three clinical isolates M. tuberculosis and the reference strain, M. tuberculosis H37Rv were tested for their susceptibility to trifluoperazine (TFP) by the standard broth dilution method and the bioluminescence assay. The results showed that in 15 of the 23 isolates, the minimal inhibitory concentration (MIC) was identical in both the methods and in the remaining 8 isolates the difference in the MIC values between the methods, was less than two fold and was not significant. The findings suggest that the measurement of adenosine triphosphate (ATP) by bioluminescence assay can be employed as an alternative method for the rapid screening of clinical isolates for their susceptibility to anti-mycobacterial agents.

Aerobic capacity and cardiopulmonary response to exercise in healthy south Indian children.

OBJECTIVE: To examine the cardiorespiratory response to exercise in healthy South Indian school children. DESIGN: Prospective study. SETTING: Cardiopulmonary Medicine Unit, Tuberculosis Research Center, Madras. SUBJECTS: Data was obtained on 47 girls and 48 boys in the age group 7 to 14 years. INTERVENTION: The children performed a graded maximal exercise stress test on a computerized treadmill system. RESULTS: Maximum oxygen consumption (VO2max) increased significantly at 11 years of age in both sexes but while boys showed a progressive increase beyond 11 years, girls did not. When corrected for weight, only boys at 14 years had a significant increase in VO2max/kg. Boys had higher values of VO2max/kg than girls at all ages. Minute ventilation and oxygen pulse values also increased in both sexes at 11 to 12 years. The VO2max of South Indian children was lower than the predicted values available for North American children when prediction equations based on height were used. However, when regression equations based on weight were used, the predicted values for North American and South Indian boys were similar, though values for the Indian girls were still low. CONCLUSIONS: Nutritional and sociocultural factors may play a role in determining VO2max of children from different populations, rather than ethnic differences alone.

Immune response & modulation of immune response induced in the guinea-pigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area.

A total of 139 guineapigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were directly sensitised/immunised with different MAC strains. M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG at this time point. However, at 6 wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the protective response resulting from BCG was observed in the guineapigs sensitised with MAC and M. fortuitum from soil.

Effect of anti-tuberculosis drugs on the iron-sequestration mechanisms of mycobacteria.

The effect of sub-lethal concentrations of isoniazid, ethambutol, rifampicin and pyrazinamide on the growth in vitro and the production of both exochelins and mycobactins by the high virulent and the South Indian low virulent strains of M. tuberculosis was examined under iron-deficient and iron-rich conditions. There was a marked decrease in the growth of both strains in the presence of increasing concentrations of all four drugs, the inhibition being total in the presence of minimal inhibitory concentrations of the drugs. It was also observed that the growth-inhibitory effect of all four drugs was slightly reversed in the presence of high concentration of iron in the medium. A significant increase was observed in the concentrations of both siderophores in the presence of all four drugs, under both iron-deficient (or) iron-rich conditions.

Effect of hemoglobin on the growth of mycobacteria and the production of siderophores.

Hemoglobin is known to support the growth of several bacterial species. The growth and the production of siderophores by 4 strains of mycobacteria in the presence of hemoglobin was studied in vitro. The findings were compared with those obtained in the presence of equivalent concentrations of iron in the medium. Increase in the concentrations of hemoglobin caused an appreciable increase in the growth of all 4 strains. This was however, accompanied by a significant decrease in the production of both exochelins and mycobactins. It was also observed that hemoglobin supported the growth of all strains as well as that with free iron and the concentrations of both siderophores was significantly higher in the presence of hemoglobin than in that of free iron.

Reference values and prediction equations for maximal expiratory flow rates in non-smoking normal subjects in Madras.

Maximal Expiratory Flow Rates such as Peak Expiratory Flow Rate (PEFR), rates at 25%, 50% and 75% of forced vital capacity (V max 25%, V max 50% and V max 75%) and forced expiratory flow during the middle half of forced vital capacity (FEF 25-75%) were measured in 273 healthy non-smoking adults (144 males, 129 females) aged 15-63 years living in Madras. Regression equations were derived for men and women for predicting maximal expiratory flow rates for adults in South India. Expiratory Flow Rates at lower lung volumes in men were similar to those reported for caucasians, but higher than those reported for western Indian Subjects. However, in women the flow rates were similar to those of western Indians and lower than those of caucasians, probably due to indoor air pollution since childhood. These data may suggest that expiratory flow rates at lower lung volumes may not show ethnic variability.

Effect of treatment on maximal expiratory flow rates in tropical eosinophilia.

Maximal expiratory flow rates such as peak expiratory flow rate (PEFR), rates at 25%, 50% and 75% of vital capacity (VE max 25%, VE max 50%, VE max 75%) and forced expiratory flow during the middle half of forced vital capacity (FEF 25-75%) were recorded in 23 patients with tropical eosinophilia (TE) before and after treatment. The mean values of all flow rates were significantly lower (P < 0.001) in untreated TE patients compared to predicted values. After three weeks' treatment with diethylcarbamazine, although there was a significant rise in the mean values of all expiratory flow rates (P < 0.05) except VE max 75% (P > 0.2), all flow rates continued to be significantly lower (P < 0.01) at one month than predicted values.

Prediction equations for maximal voluntary ventilation in non-smoking normal subjects in Madras.

Maximal voluntary ventilation (MVV) was measured in 256 healthy non-smoking adults (132 males, 124 females) aged 15-63 years living in Madras. The mean MVV (+/- SD) in males was 126.7 +/- 31.9 and in females 77.7 +/- 16.4. Regression equations were derived for men and women for predicting maximal voluntary ventilation for adults in South India. MVV in South Indians were similar to those reported for other Indian subjects, but lower than those reported for caucasians.

Peak expiratory flow rate in south Indian children.

PEFR is a simple and reliable way of following patients with bronchial asthma and other obstructive airway diseases. Normal data is available for Caucasian and North Indian children but not for ethnic South Indian children. We, therefore, measured Peak Expiratory Flow Rate (PEFR) in 345 healthy South Indian children aged 4-15 years, using the Wright mini peak flow meter. A nomogram was constructed relating PEFR to height. Prediction equations for PEFR using height alone or height, age and weight were determined for both sexes. The prediction equation for boys based on height alone was PEFR = 4.08 height (cm)--284.55 and for girls was PEFR = 3.92 height (cm)--277.01.