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.

Malabsorption of rifampin and isoniazid in HIV-infected patients with and without tuberculosis

The absorption of rifampin, isoniazid, and D-xylose in patients with human immunodeficiency virus (HIV) infection and diarrhea, in patients with HIV infection and tuberculosis (TB), in patients with pulmonary TB alone, and in healthy subjects was studied. Percentage of dose of the drugs, their metabolites, and D-xylose excreted in urine were calculated. A significant reduction in the absorption of drugs and D-xylose in both the HIV infection/diarrhea and HIV infection/TB groups was observed (P<.05), and the correlation between them was significant. Our results indicate that patients with HIV infection and diarrhea and those with HIV infection and TB have malabsorption of rifampin and isoniazid.

Standardisation and evaluation of DNA-lanthanide fluorescence spectroscopy for determining rifampicin resistance in Mycobacterium tuberculosis clinical isolates

SETTING

Tuberculosis Research Centre, Chennai.

OBJECTIVE

To rapidly identify multidrug-resistant Mycobacterium tuberculosis using a novel method.

DESIGN

A new assay, based on DNA-lanthanide fluorescence, was standardised and evaluated using 93 each of coded rifampicin-resistant and rifampicin-sensitive M. tuberculosis clinical isolates for the correct identification of rifampicin resistance. The results obtained by the new assay were compared with the conventional results.

RESULTS AND CONCLUSION

The new assay gave a sensitivity and specificity of 88% and 85%, respectively. It is simple, easy to perform and requires 48 hours for the drug susceptibility results to be available after obtaining the primary culture.

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.

Native fluorescence spectroscopy of blood plasma in the characterization of oral malignancy

Native fluorescence characteristics of blood plasma were studied in the visible spectral region, at two different excitation wavelengths, 405 and 420 nm, to discriminate patients with different stages of oral malignancy from healthy subjects. The fluorescence spectra of blood plasma of oral malignant subjects exhibit characteristic spectral differences with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values at those emission wavelengths that give characteristic spectral features of each group of experimental subjects studied. These fluorescence intensity ratios were used as input variables for a multiple linear discriminant analysis across different groups. Leave-one out cross-validation was used to check the reliability of each discriminant analysis performed. The discriminant analysis performed across normal and oral cancerous subjects classified 94.7% of the original grouped cases and 93.7% of the cross-validated grouped cases. A classification algorithm was developed on the basis of the score of the discriminant functions (discriminant score) resulted in the analyses. The diagnostic potentiality of the present technique was also estimated in the discrimination of malignant subjects from normal and nonmalignant diseased subjects such as liver diseases. In the discriminant analysis performed across the three groups, normal, oral malignancy (including early and advanced stages) and liver diseases, 99% of the original grouped cases and 95.9% of the cross-validated grouped cases were correctly classified. Similar analysis performed across normal, early stage of oral malignancy, advanced oral malignancy and liver diseases correctly classified 94.9% of the original grouped cases and 91.8% of the cross-validated grouped cases.

Mu-opioid receptors are located postsynaptically and endomorphin-1 inhibits voltage-gated calcium currents in premotor cardiac parasympathetic neurons in the rat nucleus ambiguus

Activation of opioid receptors in the CNS evokes a dramatic decrease in heart rate which is mediated by increases in inhibitory parasympathetic activity to the heart. Injection of opiates into the nucleus ambiguus, where premotor cardiac parasympathetic nucleus ambiguus neurons are located elicits an increase in parasympathetic cardiac activity and bradycardia. However, the mechanisms responsible for altering the activity of premotor cardiac parasympathetic nucleus ambiguus neurons is unknown. This study examined at the electron microscopic level whether premotor cardiac parasympathetic nucleus ambiguus neurons possess postsynaptic opioid receptors and whether mu-opioid receptor agonists alter voltage-gated calcium currents in these neurons. Premotor cardiac parasympathetic nucleus ambiguus neurons were identified in the rat using retrograde fluorescent tracers. One series of experiments utilized dual-labeling immunocytochemical methods combined with electron microscopic analysis to determine if premotor cardiac parasympathetic nucleus ambiguus neurons contain mu-opioid receptors. In a second series of experiments whole cell patch clamp methodologies were used to determine whether activation of postsynaptic opioid receptors altered voltage-gated calcium currents in premotor cardiac parasympathetic nucleus ambiguus neurons in brainstem slices. The perikarya and 78% of the dendrites of premotor cardiac parasympathetic nucleus ambiguus neurons contain mu-opioid receptors. Voltage-gated calcium currents in premotor cardiac parasympathetic nucleus ambiguus neurons were comprised nearly entirely of omega-agatoxin-sensitive P/Q-type voltage-gated calcium currents. Activation of mu-opioid receptors inhibited these voltage-gated calcium currents and this inhibition was blocked by pretreatment with pertusis toxin. The mu-opioid receptor agonist endomorphin-1, but not the mu-opioid receptor agonist endomorphin-2, inhibited the calcium currents. In summary, mu-opioid receptors are located postsynaptically on premotor cardiac parasympathetic nucleus ambiguus neurons. The mu-opioid receptor agonist endomorphin1 inhibited the omega-agatoxin-sensitive P/Q-type voltage-gated calcium currents in premotor cardiac vagal nucleus ambiguus neurons. This inhibition is mediated via a G-protein mediated pathway which was blocked by pretreatment with pertusis toxin. It is possible that the inhibition of calcium currents may act to indirectly facilitate the activity of premotor cardiac parasympathetic nucleus ambiguus neurons by disinhibition, such as by a reduction in inhibitory calcium activated potassium currents.

Endomorphin-2 inhibits GABAergic inputs to cardiac parasympathetic neurons in the nucleus ambiguus

The nucleus ambiguus is an area containing cardiac vagal neurons, from which originates most of the parasympathetic control regulating heart rate and cardiac function. GABAergic pathways to these neurons have recently been described, yet modulation of this GABAergic input and its impact upon cardiac vagal neurons is unknown. The nucleus ambiguus has been shown to contain mu-opioid receptors and endomorphin-1 and endomorphin-2, the endogenous peptide ligands for the mu-receptor, whilst microinjections of opioids in the ambiguus area evoke bradycardia. The present study therefore examined the effects of endomorphin-1, endomorphin-2 and DAMGO (a synthetic, mu-selective agonist) on spontaneous GABAergic IPSCs in cardiac parasympathetic neurons. Only endomorphin-2 (100 microM) produced a significant inhibition, of both the frequency (-22.8%) and the amplitude (-30.5%) of the spontaneous IPSCs in cardiac vagal neurons. The inhibitory effects of endomorphin-2 were blocked by naloxonazine (10 microM), a selective mu(1) receptor antagonist. Naloxonazine alone (10 microM) had a potentiating effect on the frequency of the GABAergic IPSCs (+161.43%) but not on the amplitude, indicating that GABA release to cardiac vagal neurons may be under tonic control of opioids acting at the mu(1) receptor. Endomorphin-2 did not reduce the responses evoked by exogenous application of GABA. These results indicate that endomorphin-2 acts on mu(1) receptors located on precedent neurons to decrease GABAergic input to cardiac vagal neurons located in the nucleus ambiguus. The subsequent increase in parasympathetic outflow to the heart may be one mechanism by which mu-selective opioids act to induce bradycardia.

Dose related pharmacokinetics of ofloxacin in healthy volunteers

OBJECTIVE

To evaluate the pharmacokinetic profile of ofloxacin in healthy volunteers after single oral doses of 600 and 800 mg.

DESIGN

Seven healthy volunteers were administered 600 and 800 mg of ofloxacin on two occasions with an interval of one week. Paired samples of blood and saliva were collected after 1, 2, 3, 6, 9, 12, 24, 32 and 48 hours post-dose. Urine samples were collected over a period of 0-6, 6-12 and 12-24 hours. Concentrations of ofloxacin in plasma, saliva and urine were assayed by high performance liquid chromatography.

RESULTS

Increases of 22% in peak plasma concentration (Cmax) and 40% in area under the concentration-time curve (AUC0-24) were observed with the 800 mg dose. The other parameters, namely time to attain Cmax, half-life, the apparent volume of distribution, plasma and renal clearance and percentage of dose excreted in urine over 24 hours were independent of doses. The mean ratios of the concentration in saliva to the concentration in plasma ranged from 0.4-0.6, and the correlation coefficient was 0.94.

CONCLUSIONS

Dose proportionality was observed in Cmax and AUC0-24 when 600 and 800 mg doses of ofloxacin were given. Ofloxacin determined in saliva seems to be suitable for therapeutic drug monitoring.

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.

Arginine vasopressin enhances GABAergic inhibition of cardiac parasympathetic neurons in the nucleus ambiguus

Previous studies have shown that arginine vasopressin is an important neuropeptide that can modulate the reflex control of blood pressure and heart rate. The nucleus ambiguus, where cardiac parasympathetic neurons are located, receives dense arginine vasopressin projections. However the mechanisms by which arginine vasopressin alters cardiac parasympathetic activity are unknown. We tested the hypothesis that arginine vasopressin can alter the activity of cardiac parasympathetic neurons by altering the spontaneous GABAergic input to these neurons. Experiments were conducted using whole cell patch clamp recordings of cardiac parasympathetic neurons in an in vitro slice preparation in rats. The results of this study demonstrate that arginine vasopressin increases the frequency and amplitude of GABAergic inhibitory post-synaptic currents in cardiac parasympathetic neurons. Arginine vasopressin did not alter the GABAergic currents evoked by exogenous application of GABA. Similarly, in the presence of tetrodotoxin, arginine vasopressin did not alter the frequency, amplitude or decay time of GABAergic miniature synaptic events evoked by high osmolarity. These results indicate that arginine vasopressin likely acts on neurons precedent to cardiac parasympathetic neurons and that arginine vasopressin likely acts not at the synaptic terminal but at the soma or dendrites of the precedent neuron. Oxytocin and agonists for the V(2)-arginine vasopressin and V(1b)-arginine vasopressin receptors had no effect. By contrast, the arginine vasopressin-evoked responses were completely abolished by a selective V(1a)-arginine vasopressin receptor antagonist indicating arginine vasopressin responses are mediated by V(1a)-arginine vasopressin receptors. We conclude that the V(1a)-arginine vasopressin receptor-mediated increase in frequency and amplitude of inhibitory GABAergic activity to cardiac parasympathetic neurons may be at least one mechanism by which central arginine vasopressin may increase heart rate and inhibit reflex bradycardia.

Cytogenetic studies on spray painters in south India

Studies on the frequencies of chromosomal aberrations were carried out on 104 spray painters working in automobile body reconditioning, steel furniture making and refrigerator repainting workshops in the metro city, Chennai, of south India. Randomly selected 50 male subjects not connected with this occupation were included as controls in the study. Chromosomal analysis was carried out in 48h lymphocyte (short duration) cultures representing the first mitotic division, on a subset of samples consisting of 50 spray painters, 20 controls and 72h (longer duration) cultures representing the second cell division, on all subjects. Baseline frequency of chromosomal aberrations was significantly higher among painters as compared to matched controls. Smoking and alcoholism as modulating factors had no added effect on the frequency of aberrant metaphases. Stepwise multiple linear regression analysis indicated that duration of service and age were significant factors that influence the frequency of chromosomal aberrations observed.

Synaptic and neurotransmitter activation of cardiac vagal neurons in the nucleus ambiguus

Cardiac vagal neurons play a critical role in the control of heart rate and cardiac function. These neurons, which are primarily located in the nucleus ambiguus (NA) and the dorsal motor nucleus of the vagus (DMNX), dominate the neural control of heart rate under normal conditions. Cardiac vagal activity is diminished and unresponsive in many disease states, while restoration of parasympathetic activity to the heart lessens ischemia and arrhythmias and decreases the risk of sudden death. Recent work has demonstrated that cardiac vagal neurons are intrinsically silent and therefore rely on synaptic input to control their firing. To date, three major synaptic inputs to cardiac vagal neurons have been identified. Stimulation of the nucleus tractus solitarius evokes a glutamatergic pathway that activates both NMDA and non-NMDA glutamatergic postsynaptic currents in cardiac vagal neurons. Acetylcholine excites cardiac vagal neurons via three mechanisms, activating a direct ligand-gated postsynaptic nicotinic receptor, enhancing postsynaptic non-NMDA currents, and presynaptically by facilitating transmitter release. This enhancement by nicotine is dependent upon activation of pre- and postsynaptic P-type voltage-gated calcium channels. Additionally, there is a GABAergic innervation of cardiac vagal neurons. The transsynaptic pseudorabies virus that expresses GFP (PRV-GFP) has been used to identify, for subsequent electrophysiologic study, neurons that project to cardiac vagal neurons. Bartha PRV-GFP-labeled neurons retain their normal electrophysiological properties, and the labeled baroreflex pathways that control heart rate are unaltered by the virus.

Evaluation of PCR using TRC(4) and IS6110 primers in detection of tuberculous meningitis

We have evaluated a new set of primers (TRC(4)) in comparison with the IS6110 primers commonly used in PCR to detect tuberculous meningitis among children. The levels of concordance between the results of IS6110 PCR and TRC(4) PCR with cerebrospinal fluid specimens from patients with clinically confirmed tuberculous meningitis were 80 and 86%, respectively. Results with the two primer sets were concordant for 55 positive and 22 negative specimens (n = 98). We conclude that the sensitivity of PCR can be increased by using both IS6110 and TRC(4) primers.

Site-directed sulfhydryl labeling of the lactose permease of Escherichia coli: N-ethylmaleimide-sensitive face of helix II

Cys-scanning mutagenesis of helix II in the lactose permease of Escherichia coli [Frillingos, S., Sun, J. et al. (1997) Biochemistry 36, 269-273] indicates that one face contains positions where Cys replacement or Cys replacement followed by treatment with N-ethylmaleimide (NEM) significantly inactivates the protein. In this study, site-directed sulfhydryl modification is utilized in situ to study this face of helix II. [(14)C]NEM labeling of 13 single-Cys mutants, including the nine NEM-sensitive Cys replacements, in right-side-out membrane vesicles is examined. Permease mutants with a single-Cys residue in place of Gly46, Phe49, Gln60, Ser67, or Leu70 are alkylated by NEM at 25 degrees C in 10 min, and mutants with Cys in place of Thr45 and Ser53 are labeled only in the presence of ligand, while mutants with Cys in place of Ile52, Ser56, Leu57, Leu62, Phe63, or Leu65 do not react. Binding of substrate leads to a marked increase in labeling of Cys residues at positions 45, 49, or 53 in the periplasmic half of helix II and a slight decrease in labeling of Cys residues at positions 60 or 67 in the cytoplasmic half. Labeling studies with methanethiosulfonate ethylsulfonate (MTSES) show that positions 45 and 53 are accessible to solvent in the presence of ligand only, while positions 46, 49, 67, and 70 are accessible to solvent in the absence or presence of ligand. Position 60 is also exposed to solvent, and substrate binding causes a decrease in solvent accessibility. The findings demonstrate that the NEM-sensitive face of helix II participates in ligand-induced conformational changes. Remarkably, this membrane-spanning face is accessible to the aqueous phase from the periplasmic side of the membrane. In the following paper in this issue [Venkatesan, P., Hu, Y., and Kaback, H. R. (2000) Biochemistry 39, 10656-10661], the approach is applied to helix X.

Site-directed sulfhydryl labeling of the lactose permease of Escherichia coli: helix VII

Site-directed sulfhydryl modification in situ is employed to investigate structural and dynamic features of transmembrane helix VII and the beginning of the periplasmic loop between helices VII and VIII (loop VII/VIII). Essentially all of the Cys-replacement mutants in the periplasmic half of the helix and the portion of loop VII/VIII tested are labeled by N-[(14)C]ethylmaleimide (NEM). In contrast, with the exception of two mutants at the cytoplasmic end of helix VII, none of the mutants in the cytoplasmic half react with the alkylating agent. Labeling of most of the mutants is unaltered by ligand at 25 degrees C. However, at 4 degrees C, conformational changes induced by substrate binding become apparent. In the presence of ligand, permease mutants with a Cys residue at position 241, 242, 244, 245, 246, or 248 undergo a marked increase in labeling, while the reactivity of a Cys at position 238 is slightly decreased. Labeling of the remaining Cys-replacement mutants is unaffected by ligand. Studies with methanethiosulfonate ethylsulfonate (MTSES), a hydrophilic impermeant thiol reagent, show that most of the positions that react with NEM are accessible to MTSES; however, the two NEM-reactive mutants at the cytoplasmic end of helix VII and position 236 in the middle of the membrane-spanning domain are not. The findings demonstrate that positions in helix VII that reflect ligand-induced conformational changes are located in the periplasmic half and accessible to the aqueous phase from the periplasmic face of the membrane. In the following papers in this issue (Venkatesan, P., Lui, Z., Hu, Y., and Kaback H. R.; Venkatesan, P., Hu, Y., and Kaback H. R.), the approach is applied to helices II and X.

Site-directed sulfhydryl labeling of the lactose permease of Escherichia coli: helix X

Helix X in the lactose permease of Escherichia coli contains two residues that are irreplaceable with respect to active transport, His322 and Glu325, as well as Lys319, which is charge-paired with Asp240 in helix VII. Structural and dynamic features of transmembrane helix X are investigated here by site-directed thiol modification of 14 single-Cys replacement mutants with N-[(14)C]ethylmaleimide (NEM) in right-side-out membrane vesicles. Permease mutants with a Cys residue at position 326, 327, 329, 330, or 331 in the cytoplasmic half of the transmembrane domain are alkylated by NEM at 25 degrees C, a mutant with Cys at position 315 at the periplasmic surface is labeled in the presence of substrate exclusively, and mutants with Cys at positions 317, 318, 320, 321, 324, 328, 332, or 333 do not react with NEM under the conditions tested. Binding of substrate causes increased labeling of a Cys residue at position 315 and decreased labeling of Cys residues at positions 326, 327, and 329. Studies with methanethiosulfonate ethylsulfonate indicate that Cys residues at positions 326, 329, 330, and 331 in the cytoplasmic half are accessible to the aqueous phase from the periplasmic face of the membrane. Ligand binding results in clear attenuation of solvent accessibility of Cys at position 326 and a marginal increase in accessibility of Cys at position 327 to solvent. The findings indicate that the cytoplasmic half of helix X is more reactive/accessible to thiol reagents and more exposed to solvent than the periplasmic half. Furthermore, positions that reflect ligand-induced conformational changes are located on the same face of helix X as Lys319, His322, and Glu325.

Risk of development of tuberculosis in HIV-infected patients

OBJECTIVE

To estimate the rate of development of active tuberculosis (TB) in a cohort of human immunodeficiency virus (HIV) positive patients, and to identify the characteristics of these patients.

DESIGN

A total of 175 HIV-positive individuals were recruited from clinics for sexually transmitted diseases and followed up for 31 +/- 6.8 months. Clinical examination, chest X-ray, sputum smear for acid-fast bacilli and culture for mycobacteria and HIV serology were performed at the time of registration and repeated periodically.

RESULTS

Seventeen patients had TB at intake and another 24 developed TB during follow-up, giving a breakdown rate of 6.9/100 person-years (p-y) (95% confidence interval [CI] 4.1-9.6). The attack rates were similar in tuberculin positive (7.1/100 p-y, 95%CI 3.4-10.8) and negative (6.7/100 p-y, 95%CI 2.6-10.8) patients. There was a trend towards higher mortality in patients who developed TB (10.5/100 p-y, 95%CI 4.8-15.2) compared to those who did not (6.1/100 p-y, 95%CI 3.2-8.8).

CONCLUSIONS

The results of this study provide information regarding the high risk of development of active tuberculosis and its associated mortality in HIV-infected persons. The risk of developing TB appears to be equally high in tuberculin positive and negative individuals, suggesting that new infections could play a major role in this susceptible population.

Structure-activity relationships for the inhibition of lipid peroxidation and the scavenging of free radicals by synthetic symmetrical curcumin analogues

A number of ring substituted analogues of curcumin were synthesized. Their antioxidant properties were studied using three models, inhibition of lipid peroxidation, scavenging of 1,1'-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethyl-benzthiazoline-6-sulphonate radical (ABTS+.). In all the models, the phenolic analogues were more active than the non-phenolic analogues, some of which were inactive. The highest antioxidant activity was obtained when the phenolic group was sterically hindered by the introduction of two methyl groups at the ortho position. This and several other compounds were more active than the standard antioxidants alpha-tocopherol and trolox. This study has demonstrated that the phenolic group is important for the antioxidant activity of curcumin and that the structural features that enhance the antioxidant properties of phenols are optimized in curcumin to a significant extent.

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.

Inhibition of radiation-induced lipid peroxidation by tetrahydrocurcumin: possible mechanisms by pulse radiolysis

The antioxidant property of tetrahydrocurcumin (THC), a reduced derivative of curcumin, was examined by its ability to inhibit radiation-induced lipid peroxidation in rat liver microsomes and compared with curcumin. The lipid peroxidation caused by irradiation of N2O-purged and aerated buffered aqueous solutions was found to be inhibited by THC in a dose- and concentration-dependent manner. In order to understand the actual reaction mechanisms involved in the inhibition process, pulse radiolysis investigation of THC with radiolytically produced radicals like hydroxyl, model peroxyl radicals, and azide radicals were done and the transients were detected by kinetic spectrophotometry. The reaction of THC with hydroxyl and azide radicals gave rise to transient absorption in the region 200-400 nm with two peaks at 310 nm and 390 nm. From the spectral properties and kinetics of these radicals, a suitable mechanism is discussed to explain the antioxidant actions of THC.

Socio-economic impact of tuberculosis on patients and family in India

OBJECTIVE

To quantify the socio-economic impact of tuberculosis on patients and their families from the costs incurred by patients in rural and urban areas.

DESIGN

An interview schedule prepared from 17 focus group discussions was used to collect socio-economic demographic characteristics, employment, income particulars, expenditure on illness and effects on children from newly detected sputum-positive pulmonary tuberculosis patients. The direct and indirect costs included money spent on diagnosis, drugs, investigations, travel and loss of wages. Total costs were projected for the entire 6 months of treatment.

RESULTS

The study population consisted of 304 patients (government health care 202, non governmental organisation 77, private practitioner 25), 120 of whom were females. Mean direct cost was Rs.2052/-, indirect Rs.3934/-, and total cost was Rs.5986/- ($171 US). The mean number of work days lost was 83 and mean debts totalled Rs.2079/-. Both rural and urban female patients faced rejection by their families (15%). Eleven per cent of schoolchildren discontinued their studies; an additional 8% took up employment to support their family.

CONCLUSIONS

The total costs, and particularly indirect costs due to TB, were relatively high. The average period of loss of wages was 3 months. Care giving activities of female patients decreased significantly, and a fifth of schoolchildren discontinued their studies.

Free radical scavenging ability and antioxidant efficiency of curcumin and its substituted analogue

Free radical reactions of curcumin and its ethoxy substituted derivative (C1) 1,7-bis-(4-hydroxy-3-ethoxy phenyl)-1,6-heptadiene-3,5-dione have been studied using a pulse radiolysis technique in homogeneous aqueous-organic solutions like acetonitrile-water and isopropanol-water mixtures, as well as in neutral TX-100 and cationic CTAB micellar solutions. The phenoxyl radicals of curcumin or C1 were generated by one-electron transfer to several oxidants like N(3)(.), Br(2)(-.), CCl(3)O(2)(.), glutathione radicals which exhibit absorption from a 300-600-nm wavelength region with the maximum at 490-500 nm. Other important properties of the phenoxyl radicals such as extinction coefficient, radical lifetime and their formation and decay rate constants were also determined in these systems. The antioxidant property of curcumin and C1 were estimated in terms of their ability to inhibit the lipid peroxidation in liposomes and also in terms of trolox equivalent antioxidant capacity (TEAC). The results were compared with alpha-tocopherol.