Free radicals and theophylline neurotoxicity : an experimental study

Free radicals play a crucial role in health and disease and both reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been implicated in CNS effects like excitotoxicity. Theophylline, a re-emerging drug for the treatment of obstructive airway disease, has a narrow therapeutic index which precludes its safe use. The present study evaluated the possible involvement of free radicals in theophylline induced seizures in mice. Aminophylline (100-250 mg/kg) consistently induced seizures and post-ictal mortality, and conventional anticonvulsants and adenosine agonists were ineffective in antagonizing them. Further, phosphodiesterase inhibitors, per se, also did not show any significant seizurogenic potential. Pretreatments with antioxidants, ascorbic acid, alpha-tocopherol and melatonin, all dose dependently reduced seizure incidence and mortality after aminophylline, whereas, antioxidant depletion potentiated such excitotoxicity. Pretreatments with the NO synthase inhibitors, L-NAME and 7-NI blocked aminophylline seizures, whereas, the NO mimetics, L-arginine and glyceryl trinitrate, tended to potentiate this phenomenon. Sub-effective doses of aminophylline (100 mg/kg) also induced seizures when combined with subthreshold intensity of electroshock, and such seizures were similarly antagonized by the antioxidants and NO synthase inhibitors. Biochemical assay of brain homogenates showed that aminophylline seizures were associated with enhancements in brain MDA and NOx (NO metabolites) levels, whereas, SOD activity was reduced, and these changes were attenuated after melatonin and L-NAME pretreatments. The pharmacological and biochemical data are strongly suggestive of the involvement of both ROS and RNS during theophylline-induced seizures.

How to diagnose and manage common parasitic pneumonias

PURPOSE OF REVIEW

Parasitic pneumonia is being increasingly reported from many parts of the world due to globalization and travel across the continents. This review outlines the recent developments in the diagnosis and management of parasitic pneumonias.

RECENT FINDINGS

A polymerase chain reaction that can differentiate pathogenic Entamoeba histolytica from nonpathogenic species has been reported. It has been observed that pulmonary infection with Leishmania donovani can occur in immunodeficient and lung transplant patients. Acute respiratory distress syndrome, seen in severe falciparum malaria, has also been observed in vivax malaria. A study has demonstrated the return of chloroquine-sensitive falciparum malaria several years after chloroquine treatment was discontinued. Pulmonary hypertension has been reported in Schistosoma hematobium, S. mansoni and S. japonicum infections. Strongyloides hyperinfection and disseminated disease are frequently reported in immunocompromised individuals. Parenteral ivermectin is found to be useful in the treatment of disseminated strongyloidiasis. A chronic mild interstitial lung disease has been found to persist in tropical pulmonary eosinophilia despite treatment. Studies are in progress to develop vaccines against amoebiasis, malaria and hookworm infections.

SUMMARY

Parasitic pneumonia can sometimes be life threatening. If proper diagnosis is made early, the pneumonia can be treated successfully with currently available drugs.

Involvement of nitric oxide (NO) in the regulation of stress susceptibility and adaptation in rats

The present study evaluated the regulatory role of nitric oxide (NO) in stress susceptibility and adaptation in rats. Acute restraint stress (RS x1) reduced the number of entries and time spent in the open arms in the elevated plus maze (EPM) test and raised plasma corticosterone levels. RS (x1)-induced neurobehavioral suppression and raised corticosterone levels were attenuated by pretreatment with the NO precursor, L-arginine (500 and 1000 mg/kg)and unaffected or further aggravated by NO synthase inhibitor, L-NAME or 7-nitroindazole (10 and 50 mg/kg). Biochemical assay of plasma and brain homogenates showed that these RS - induced behavioral and neuroendocrinal changes were associated with lowered levels of plasma and brain total nitrates/nitrites (NOx). L-Arginine attenuated the RS-induced suppression of NOx levels in plasma and brain, whereas, the NO synthase inhibitors tended to produce reverse effects. In the experiments involving repeated stress i.e. RS (x5), exposure resulted in attenuation/reversal of (a) neurobehavioral suppression in the EPM test and (b) lowered brain NOx, that was seen after RS (x1). The RS (x5)-induced changes in EPM parameters and brain Nox were further potentiated after L-arginine pretreatment, whereas, the NO synthase inhibitors were less effective. Rats were screened as high and low emotional in the open-field test, and high emotional rats showed greater(a) behavioral suppression in the EPM, (b) corticosterone responses (c) brain NOx suppression, and (d) cold-restraint stress (CRS) induced gastric mucosal lesions as compared to their low emotional counterparts. L-Arginine pretreatment was more effective in modulating the above RS induced stress responses/markers in the high emotional group of rats. Our data suggest that NO plays a differential role during exposure to acute and repeated stress situations, and that the relationship between stress and emotionality status may be under the regulatory influence of NO.

High intensity exercise training programme following cardiac transplant

A 26-year-old male patient who presented with symptoms of end stage cardiac failure as a result of dilated cardiomyopathy, had an orthotopic cardiac transplantation. A comprehensive cardiac rehabilitation programme was provided to him and he was introduced to a sport (tennis). The exercise training programme progressed from low intensity training to high intensity programme over a period of 15 months. A cardio-pulmonary exercise test done 22 months after surgery suggested that he was able to achieve the aerobic capacity comparable to that of a normal South Indian subject. He participated successfully in the World Transplant Games in Sydney and returned safely. This suggests that after a proper cardiac rehabilitation programme, patients undergoing heart transplantation can achieve normal physiological responses to lead a normal active life.

Evaluation of peptone glucose fluconazole agar as a selective medium for rapid and enhanced isolation of Aspergillus fumigatus from the respiratory tract of bronchopulmonary aspergillosis patients colonized by Candida albicans

We have reported earlier that Aspergillus fumigatus is inhibited in vitro by Candida albicans which also interferes in its isolation from sputum experimentally seeded with predetermined graded inocula of the two fungi. It was further shown that this interference was neutralized by employing peptone glucose agar with incorporation of fluconazole which is more inhibitory to C. albicans than to A. fumigatus. This communication embodies the results of evaluation of peptone glucose fluconazole agar (PGFA) as a selective culture medium for rapid and enhanced isolation of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in the respiratory tract. Of the 23 sputum specimens and one broncho-alveolar lavage collected from 15 suspected aspergillosis patients, A. fumigatus was isolated from all (100%) on PGFA as against only 19 specimens (79%) that proved to be positive on the control PGA medium (P<0.05). The greater efficacy of PGFA than that of PGA was further evident from the 2-fold higher A. fumigatus mean colony count (8.2+/-1.87) on the former medium than on the latter (3.7+/-1.00), and this difference was found to be statistically significant (P<0.05). Besides, A. fumigatus colonies were macroscopically recognizable within 2-3 days on PGFA at 28 degrees C in strong contrast to 5-7 days required on PGA. Based upon these observations, PGFA is recommended for wider application as a selective medium for rapid and enhanced recovery of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in their respiratory tract.

Inhaled formoterol versus ipratropium bromide in chronic obstructive pulmonary disease

BACKGROUND

Short-acting anticholinergic bronchodilator, ipratropium bromide has been recommended as first-line drug in chronic obstructive pulmonary disease (COPD). More recently, long acting beta2-agonist (LABA) bronchodilators such as formoterol have been shown to be useful in COPD. Limited information is available on the relative efficacy of these two drugs in COPD.

METHODOLOGY

A randomised, double-blind, cross-over, placebo-controlled study was carried out. Forty-four stable patients with COPD received single doses of formoterol (12 microg), ipratropium bromide (40 microg) or placebo, administered through a metered-dose inhaler on three consecutive days in a random order. Spirometry, static lung volumes, pulse rate and blood pressure, and assessment of sensation of dyspnoea at rest using a visual analog scale (Borg Scale) were recorded at baseline. Subsequently, these were repeated for assessment of response: spirometry at 5, 30 and 60 minutes and static lung volumes, pulse rate, blood pressure and dyspnoea measurement at 60 minute.

RESULTS

Formoterol resulted in greater immediate improvement in lung function, with the change in FEV1 at 5 min being greater than that observed with ipratropium. The changes in static lung volumes were similar between the two but superior to placebo. Both the drugs reduced dyspnoea. Formoterol produced a significantly greater increase in heart rate and systolic blood pressure as compared to ipratropium, although the magnitude of these changes was small and clinically unimportant.

CONCLUSIONS

Single therapeutic doses of formoterol and ipratropium bromide are equally effective in improving lung function and reducing dyspnoea. However, formoterol appears to be a better bronchodilator producing a faster improvement in lung function.

Biological and epidemiological aspects of influenza virus H5N1 in context of India

Since 1997, highly pathogenic avian influenza (HPAI) H5N1 virus crossed the species barriers from birds to humans and caused fatal disease, leading to great speculation about a possible influenza pandemic. This subtype is characterized by its pathogenicity in a large number of animal species and resistance to older class of antiviral drugs. At present, two out of three general conditions for the onset of pandemic have been met, emergence of new virus; and its ability to replicate in humans causing serious illness. Next influenza pandemic might be due to human to human transmission. This review addresses the biological and epidemiological aspects of influenza in context of India.

A multicentric study on epidemiology of chronic obstructive pulmonary disease and its relationship with tobacco smoking and environmental tobacco smoke exposure

INTRODUCTION

Population prevalence of chronic obstructive pulmonary disease (COPD) and its relationship with tobacco smoking, environmental tobacco smoke (ETS) exposure and other variables were studied in adult subjects of 35 years and above at four different centres in India. Question-items for the diagnosis of COPD were included in the questionnaire used for the field study on asthma epidemiology.

METHODS

Field surveys were conducted in both the urban and the rural populations at Bangalore, Chandigarh, Delhi and Kanpur with the help of a structured and validated questionnaire for diagnosis of asthma and COPD. Separate sets of questions were used for the diagnoses of the two diseases. A two-stage stratified sample design was employed where a village or an urban locality formed the first stage unit and a household formed the second stage unit. A uniform methodology was used at all the four centres and the analyses were done at the central coordinating centre--Chandigarh. Chronic obstructive pulmonary disease, defined by chronic bronchitis (CB) criteria, was diagnosed from the presence of cough and expectoration on most of the days for at least three months in a year for two consecutive years or more.

RESULTS

Chronic obstructive pulmonary disease was diagnosed in 4.1% of 35295 subjects, with a male to female ratio of 1.56:1 and a smoker to nonsmoker ratio of 2.65: 1. Prevalence among bidi and cigarette smokers was 8.2% and 5.9%, respectively. Odds ratio (OR) for COPD was higher for men, elderly individuals, lower socio-economic status and urban (or mixed) residence. Environmental tobacco smoke exposure among nonsmokers had an OR of 1.4(95% CI 1.21-1.61). Combined exposure to both ETS and solid fuel combustion had higher OR than for ETS exposure alone.

CONCLUSIONS

Population prevalence of COPD is very high in India with some centre to centre differences. Smoking of both bidis and cigarettes, and ETS exposure among nonsmokers, were two important risk factors at all centres. It is important to employ uniform methodology for assessment of national burden and disease-surveillance programme.

Tobacco smoking in India: prevalence, quit-rates and respiratory morbidity

BACKGROUND

Population prevalence of tobacco smoking especially with reference to detailed habits such as the amount smoked, the smoking forms, quit-rates and relationship with demographic variables were studied at four different centres in India along with the study on epidemiology of asthma and chronic obstructive pulmonary disease.

METHODS

The study population included adults of over 15 years of age selected with two-stage stratified random sample design. A specifically designed questionnaire was used for the study.

RESULTS

There were 11496 (15.6%) ever smokers in the study sample of 73605 subjects. Among 37682 males, 10756 (28.5%) were ever smokers and among 35923 females, 740 (2.1%) were ever smokers. Bidi was the commonest form of smoking, more so in the rural areas. The mean number of cigarettes/bidis smoked per day was 14 (+/- 11.5) and the mean age of starting smoking was 20.5 (+/- 20.0) years. Increasing age, low socio-economic status and rural residence were important factors associated with smoking. Vigorous anti-tobacco measures under the tobacco control programmes yielded only a quit-rate of 10 percent. Nearly 14% of ever smokers had some respiratory symptoms.

CONCLUSIONS

A substantial proportion of population in India has current or past smoking habit with higher prevalence among males than females. The quit-rates have been low in spite of the various anti-tobacco measures. There is a significant respiratory morbidity associated with smoking.

Prevalence and risk factors for bronchial asthma in Indian adults: a multicentre study

BACKGROUND

There is limited information on field epidemiology of bronchial asthma in Indian adults.

OBJECTIVES

To estimate prevalence of bronchial asthma in different regions of India and to define risk factors influencing disease prevalence.

METHODS

A field study was conducted at Chandigarh, Delhi, Kanpur and Bangalore through a two stage stratified (urban/ rural) sampling and uniform methodology using a previously validated questionnaire. Asthma was diagnosed if the respondent answered affirmatively both to (a) whistling sound from chest, or chest tightness, or breathlessness in morning, and (b) having suffered from asthma, or having an attack of asthma in the past 12 months, or using bronchodilators. Besides demographic data, information on smoking habits, domestic cooking fuel used, atopic symptoms, and family history suggestive of asthma was also collected. Univariate and multivariate logistic regression modelling was performed to calculate odds ratio of various potential risk factors.

RESULTS

Data from 73605 respondents (37682 men, 35923 women) were analysed. One or more respiratory symptoms were present in 4.3-10.5% subjects. Asthma was diagnosed in 2.28%, 1.69%, 2.05 and 3.47% respondents respectively at Chandigarh, Delhi, Kanpur and Bangalore, with overall prevalence of 2.38%. Female sex, advancing age, usual residence in urban area, lower socio-economic status, history suggestive of atopy, history of asthma in a first degree relative, and all forms of tobacco smoking were associated with significantly higher odds of having asthma.

CONCLUSION

Prevalence estimates of asthma in adults in this study, although lower than several previously reported figures, point to a high overall national burden of disease.

Household environmental tobacco smoke exposure, respiratory symptoms and asthma in non-smoker adults: a multicentric population study from India

BACKGROUND

Exposure to environmental tobacco smoke (ETS) is a risk factor for childhood asthma. Its association with asthma in adults is less clear.

METHODS

In a multicentric population study on asthma prevalence in adults, specific enquiries were made into childhood and adulthood exposure to household ETS, and its relationship with asthma diagnosis were analysed.

RESULTS

From a total of 73605 respondents, 62109 were studied after excluding current or past smokers. Overall observed prevalence of asthma was 2.0% (men 1.5%,women 2.5%, p < 0.001). Of all asthma patients, history of ETS exposure was available in 48.6 percent. Prevalence of asthma in the ETS exposed subjects was higher compared to non-exposed individuals (2.2% vs 1.9%, p < 0.05). Multiple logistic regression analysis showed a higher risk of having asthma in persons who were exposed to ETS compared to those not exposed (odds ratio [OR] 1.22, 95% CI 1.08-1.38) after adjusting for age, gender, usual residence, exposure to biomass fuels and atopy. Stratification of ETS exposure revealed that exposure during childhood and both during childhood and adulthood were significantly associated with asthma prevalence. Exposure only in adulthood was not a significant risk factor (OR 1.13, 95% CI 0.95-1.33). Persons reporting combined environmental tobacco smoke exposure from parents during childhood and spouse during adulthood had highest risk of having asthma (OR 1.69, 95% CI 1.38-2.07). Environmental tobacco smoke exposure was also significantly associated with prevalence of respiratory symptoms such as wheezing, cough and breathlessness.

CONCLUSIONS

Environmental tobacco smoke exposure during childhood is an important risk factor for asthma and respiratory symptoms in non-smoking adults.

Pharmacological studies on mechanisms of aminophylline-induced seizures in rats

In the present study, the possible role of free radicals in aminophylline-induced seizures was evaluated in albino rats. Aminophylline (theophylline in ethylene diamine; 50 - 300 mg/kg) induced convulsions in rats in a dose-dependent manner, and both incidence of seizure and mortality were maximum at 300 mg/kg. Conventional anti-epileptics, diphenylhydantoin and dizocilpine, as well as adenosine agonists were ineffective in antagonizing these seizures. On the other hand, phosphodiesterase inhibitors, pentoxyphylline and rolipram, showed insignificant seizurogenic effects. Pretreatment with antioxidants (ascorbic acid, alpha-tocopherol, and melatonin) showed differential attenuating effects on aminophylline seizures and lethality. Further, prior administration of 1-buthionine sulfoxamine (BSO, glutathione depletor) and triethyltetramine (TETA, superoxide dismutase inhibitor), precipitated seizures and enhanced lethality in response to subthreshold doses of aminophylline. The present results suggested of the possible involvement of oxidative stress during aminophylline-induced seizures.

Possible role of free radicals in theophylline-induced seizures in mice

Theophylline is a methylxanthine bronchodilator with a narrow therapeutic index and is prone to induce seizures, the mechanisms for which are not clearly defined. Free radicals have considerable neurotoxic potential and the present study evaluated the possible involvement of these bioactive moieties in aminophylline-induced seizures in mice. Aminophylline (50-250 mg/kg) induced convulsions and mortality in mice in a dose-dependent manner. The anti-oxidants, melatonin (25-100 mg/kg) and N-actylcysteine (100 and 200 mg/kg) attenuated aminophylline seizures and mortality. Similar antagonism of aminophylline seizures was also observed after pretreatments with nitric oxide (NO) synthase inhibitors, L-NAME (3 and 10 mg/kg) and 7-nitroindazole (10 and 30 mg/kg). Further, combined treatment with otherwise sub-effective doses of melatonin and L-NAME or 7-nitroindazole produced marked protective effects against these seizures. Aminophylline-induced seizures enhanced malondialdehyde (MDA) concentrations and NO metabolite (NOx) levels in the brain homogenates of mice, and these were attenuated by melatonin and L-NAME pretreatments. The results are suggestive of the possible involvement of free radicals (reactive oxygen and reactive nitrogen species) in the convulsiogenic effects of aminophylline.

Pharmacological and biochemical studies on the possible role of nitric oxide in stress adaptation in rats

The involvement of nitric oxide (NO) in stress adaptation was evaluated in rats using the elevated plus maze test. Repeated restraint stress RS(x 5) for 5 days resulted in an increase in the percentage number of entries and percentage time spent when compared to a single restraint stress RS(x 1) exposure. In the repeated RS treatment groups, the nitric oxide donor, L-arginine (500 and 1000 mg/kg, i.p.) slightly increased the elevated plus maze test parameters when compared to the corresponding vehicle-treated group. The nitric oxide synthase (NOS) inhibitors, N-nitro-L-arginine methyl ester (L-NAME, 10 and 50 mg/kg, i.p.) and 7-nitroindazole (10 and 50 mg/kg, i.p.) produced differential responses in both the parameters with L-NAME exhibiting greater reduction in open arm entries and open arm time, whereas 7-nitroindazole produced only small differences in both the elevated plus maze parameters. Biochemical data showed that repeated restraint stress resulted in higher levels of brain nitrates and nitrites (NOx) as compared to that of single restraint stress exposure. Further, in L-arginine (1000 mg/kg, i.p.)-treated rats, brain NOx was lowest in the single restraint stress group, followed by repeated restraint stress and (no restraint stress) controls. The results are suggestive of the role of nitric oxide in stress adaptation and this may be due to the effects of restraint stress on brain NOS activity.

Pharmacotherapy of tobacco dependence

Smoking cessation activities and support for its implementation should be integrated into the health care system. The outcome of smoking cessation has improved with the availability of proper behavior approaches and medications. Incorporating these guidelines into daily clinical practice ensures that health care providers provide the opportunity for patients to quit smoking. The best hope of improved treatment comes from combining existing and new pharmacotherapies with effective behavioral therapy.

Reduced exercise capacity in non-cystic fibrosis bronchiectasis

OBJECTIVE

Bronchiectasis not due to cystic fibrosis is usually a consequence of severe bacterial or tuberculous infection of the lungs, which is commonly seen in children in developing countries. Our aim was to study its functional sequelae and affect on work capacity in children.

METHODS

Seventeen children (7-17 years of age) with clinical and radiological evidence of bronchiectasis of one or both lungs were studied at the Cardiopulmonary Unit of the Tuberculosis Research Centre. Pulmonary function tests including spirometry and lung volume measurements were performed. Incremental exercise stress test was done on a treadmill, and ventilatory and cardiac parameters were monitored. Control values were taken from a previous study.

RESULTS

Children with bronchiectasis had lower forced vital capacity (FVC) (1.1 + 0.4 L versus 1.5 + 0.4 L, p = 0.003) and FEV1 (0.95 +/- 0.2 L versus 1.4 +/- 0.3 L, p < 0.002) compared to age- and sex-matched healthy controls. The patient group had significantly higher residual lung volumes (0.7 +/- 0.3 L versus 0.4 + 0.1 L, p < 0.02). At maximal exercise, they had lower aerobic capacity (28 +/- 6 ml/min/kg versus 38 +/- 5 ml/min/kg, p < 0.0001) and maximal ventilation (24 +/- 8 L/min versus 39 +/- 10 L/min, p < 0.001). At maximal exercise, while none of the controls desaturated, oxygen saturation fell below 88% in eight of 17 patients.

CONCLUSION

The findings show that children and adolescents with non-cystic fibrosis bronchiectasis have abnormal pulmonary function and reduced exercise capacity. This is likely to interfere with their life as well as future work capacity. Efforts should be made to minimize lung damage in childhood by ensuring early diagnosis and instituting appropriate treatment of respiratory infections.

Chronic Klebsiella pneumonia in an immunocompetent host

A 55 years immunocompetent male was evaluated for chronic pulmonary disease of over 12-month duration for which he had twice been prescribed anti-tubercular therapy. Investigations led to the diagnosis of chronic Klebsiella pneumonia, which is rarely encountered in immunocompetent hosts in the antibiotic era.

Modulation of stress-induced neurobehavioral changes by nitric oxide in rats

The involvement of nitric oxide (NO) in stress-induced neurobehavioral changes in rats was evaluated using the elevated plus maze and open field tests. Restraint stress (1 h) reduced both the number of entries and time spent in open arms, with both expressed as percent of controls (no restraint stress), and these changes were reversed with diazepam (1 mg/kg) and the NO precursor, L-arginine (500 and 1000 mg/kg) pretreatment. The nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) (50 mg/kg), aggravated restraint stress effects in the elevated plus maze test, whereas the lower dose (10 mg/kg) of the drug attenuated the same. In the open field test, the restraint stress-induced (a) increased entry latency and (b) decreased ambulation and rearing were reversed by diazepam and L-arginine and L-NAME (10 mg/kg), whereas L-NAME (50 mg/kg) aggravated restraint stress effects. The neuronal nitric oxide synthase inhibitor, 7-nitroindazole (10 and 50 mg/kg), did not influence these restraint stress-induced behavioral changes to any significant extent. Biochemical data showed that L-NAME (10 and 50 mg/kg.) induced opposite effects on the total brain nitrate/nitrite content during restraint stress. The results indicate a possible involvement of NO in stress-induced neurobehavioral effects.