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Biomedical subjects

A Prakash

Publications and source records attributed to A Prakash.

At least 91 records · Page 5Linked to original sources
PubMed1997

Breeding and day resting habitats of Anopheles dirus in Assam, India.

Longitudinal surveys at monthly frequency were carried out during 1995-1996 in a forest fringed village of district Dibrugarh, Assam to decipher the breeding and day resting habitats of Anopheles dirus. It regularly bred in small, shallow, rain filled, transient, shady or partly shady puddles/ground pools in the rainy months and in the perinneal streams in the adjoining forest of the village during dry months. In pools, the degree of interspecific association (0.238 +/- 0.174) and index of association (0.428) of An. dirus breeding was highest with Aedes caecus. An. dirus was completely exophilic and rested during day time in the forest mostly on tree trunks upto the height of 4-5 feet from the ground in dark moist niches avoiding direct sun light.

Animals↗
PubMed1997

The role of pacemaker therapy in the prevention of atrial fibrillation.

Atrial fibrillation (AF) has been recognized, with increasing concern, as a potentially disabling illness, occurring either as a symptom of many cardiac diseases or as an isolated disorder. It can independently contribute to mortality and morbidity and may have serious prognostic importance in acute or chronic cardiac disease. In patients with symptomatic drug refractory atrial fibrillation, ventricular rate control by atrioventricular nodal ablation or modification commonly results in pacemaker implantation. The concept of AF prevention by pacemaker therapy has been introduced in patients with bradycardia-tachycardia syndrome or vagally mediated bradycardia-dependent AF. In patients with sick sinus syndrome, atrial pacing has proved to be more effective than VVI pacing in maintaining the electrical stability of the atrium in long-term follow up. Recently, the development of new techniques of atrial pacing employing pacing at two atrial sites may improve the effectiveness of the AF prevention by pacemaker therapy. Dual-site right atrial pacing using overdrive stimulation activates simultaneously the high right atrium and the left atrium via the ostium of the coronary sinus. Two main mechanisms have been proposed to explain the favourable effect of this technique. One is the suppression of atrial premature beats initiating AF by the overdrive pacing. The second is the alteration of atrial activation pattern by preexcitation of the area of the coronary sinus ostium which permits earlier recovery of excitability in sites of atrial conduction delay. The combination of drug therapy and pacing is essential for effective AF control. We have hitherto studied 30 patients with single- and dual-site pacing. Single-site pacing was performed at the high right atrium or coronary sinus ostium. The dual-site pacing mode increased the arrhythmia-free intervals, decreased patients' arrhythmia-related symptoms and anti-arrhythmic drug use as compared to the period preceding institution of pacing and incrementally over conventional high right atrial pacing alone. A multicentre randomized trial, Dual-site Atrial Pacing for Prevention of Atrial Fibrillation (DAPPAF), evaluating three pacing modes (dual-site, single-site and support pacing), is now in progress.

Atrial Fibrillation↗
PubMed1996

Prevention of recurrent atrial fibrillation with chronic dual-site right atrial pacing.

OBJECTIVES: We investigated 1) the feasibility, safety and efficacy of multisite right atrial pacing for prevention of atrial fibrillation (AF); and 2) the ability of atrial pacing in single- and dual-site modes to increase arrhythmia-free intervals in patients with drug-refractory AF. BACKGROUND: We recently developed and applied a novel technique of dual-site right atrial pacing in an unselected group of consecutive patients with AF requiring demand pacing. A prospective crossover study design was used to evaluate single- and dual-site right atrial pacing modes. METHODS: The frequency of AF during the 3 months before pacemaker implantation was analyzed. Consecutive consenting patients underwent insertion of two atrial leads and one ventricular lead with a DDDR pulse generator. Patients were placed in a dual-site pacing mode for the first 3 months and subsequently mode switched to single site pacing for 3 months. Mode switching was repeated at 6-month intervals thereafter. RESULTS: Atrial pacing resulted in a marked decline in AF recurrences (p < 0.001). During dual-site pacing with an optimal drug regimen, there was no AF recurrence in any patient compared with five recurrences in 12 patients during single-site pacing (p = 0.03). The mean (+/-SD) arrhythmia-free interval before pacing (14 +/- 14 days) was prolonged with dual- (89 +/- 7 days, p < 0.0001) and single-site pacing (76 +/- 27 days, p < 0.0001). Symptomatic AF episodes showed a declining trend during dual- and single-site pacing compared with those during the preimplantation period (p = 0.10). Mean antiarrhythmic drug use for all classes declined from 4 +/- 1.9 drugs before implantation to 1.5 +/- 0.5 (p < 0.01) drugs after implantation. Twelve (80%) of 15 patients remained in atrial paced rhythm at 13 +/- 3 months. CONCLUSIONS: We conclude that multisite right atrial pacing is feasible, effective and safe for long-term application. Atrial pacing significantly prolongs arrhythmia-free intervals in patients with drug-refractory paroxysmal AF. Dual-site right atrial pacing may offer additional benefits and should be considered either as the primary mode or in patients unresponsive to single-site pacing.

Adult↗
PubMed1996

New generations of implantable pacemaker defibrillators for ventricular and atrial tachyarrhythmias.

Implantable defibrillation devices have now been extensively applied to patients requiring cardioversion and defibrillation of sustained ventricular tachyarrhythmias. The focus of new developments is in improving technology, achieving physiologic operation in the atrium and ventricle, seeking new indications and identifying patient populations amenable to this therapy. Ventricular application technology is focusing on simplifying and improving robustness of lead systems yet seeking lower defibrillation thresholds. Dual chamber pacing, sensing and defibrillation are being developed. New populations for ventricular application include non-sustained ventricular tachycardia patients with coronary artery disease, dilated cardiomyopathy at risk for sudden death, long QT syndrome, pediatric patients with risk of sudden death and high risk postoperative coronary bypass patients. New applications include atrial defibrillation combined with atrial pacing in future devices. These devices are planned to have capabilities of ventricular defibrillation as a backup to address proarrhythmia concerns. It can be anticipated that implantable cardioverter defibrillator devices will be used for arrhythmia reversion in an expanding group of patients in the future.

Arrhythmias, Cardiac↗
PubMed1996

Effect of arteether alpha/beta on uncomplicated falciparum malaria cases in Upper Assam.

Thirty patients of uncomplicated Plasmodium falciparum malaria completed a clinical trial of arteether alpha/beta conducted in a malaria endemic tea garden of district Dibrugarh, Assam. Arteether was given intramuscularly in once a day dose of 150 mg for three consecutive days. The cure rate was 100 per cent with mean fever and parasite clearance time of 42.4 +/- 17.5 and 37.6 +/- 13.6 h respectively. Recrudescence/reinfection rate was 6.7 per cent. Palpable spleens of twenty out of twenty one cases on day 0 became non palpable within 28 days. Following the treatment, percentage of hemoglobin improved marginally with no remarkable change in total and differential leucocyte count. Arteether alpha/beta, besides being a potent and fast acting schizontocidal drug, also exhibited gametocytocidal action on P. falciparum.

Adolescent↗
PubMed1996

Vector incrimination in Tamulpur primary health centre, district Nalbari, lower Assam during malaria outbreak 1995.

A widespread outbreak of malaria occurred in different districts of lower Assam in April, 1995. Entomological investigations were carried out in Primary Health Centre Tamulpur, the worst hit area of Nalbari district. Of the nine anopheline species collected, Anopheles minimus was incriminated as the malaria vector with sporozoite rate of 6.5 per cent. The slow moving streamlets were identified as the sole breeding places of An. minimus.

Animals↗
PubMed1995

Clinical efficacy and safety of atrial defibrillation using biphasic shocks and current nonthoracotomy endocardial lead configurations.

We undertook a prospective randomized clinical trial evaluating efficacy and safety of internal atrial defibrillation in patients with drug-refractory atrial fibrillation (AF). Consecutive patients with paroxysmal or chronic AF were randomly tested with 3 internal atrial defibrillation lead configurations and biphasic shocks. Patients with implanted cardiac pacemakers were tested with the right atrium (RA) and left pulmonary artery or coronary sinus (CS) configuration. Shocks were initially delivered without anesthesia to assess patient tolerance. The need for backup ventricular defibrillation and pacing support was evaluated. Eighteen patients with (n = 15) or without (n = 3) structural heart disease, mean left ventricular ejection fraction 36 +/- 14%, and mean left atrial diameter 4.5 +/- 0.6 cm were studied. The mean defibrillation threshold in the best randomized lead configuration was 9.9 +/- 7.7 J. Mean defibrillation threshold for the right ventricle (RV) and superior vena cava configuration was 13.3 +/- 5 J, which was significantly lower than the RA and axilla configuration (20.1 +/- 7.4 J, p < 0.04) but not the RV to RA configuration (16.5 +/- 11 J, p > 0.2). The mean defibrillation threshold using the RA-left pulmonary artery/CS configuration was 8.9 +/- 9 J (p > 0.2 vs RV-superior vena cava). There was a bimodal distribution of defibrillation thresholds. Low atrial defibrillation thresholds correlated with absence of heart disease, higher ejection fraction, and smaller left ventricular end-diastolic diameter. Shocks were hemodynamically well tolerated, but 2 of 18 patients (11%) had nonsustained ventricular tachycardia after shock delivery. Six of 18 patients (33%) had postshock bradyarrhythmias. Fourteen of 16 patients perceived shocks > or = 3 J as intolerable.(ABSTRACT TRUNCATED AT 250 WORDS) [corrected]

Adult↗
PubMed1995

Electrophysiology in a district general hospital.

OBJECTIVE: To investigate the feasibility of performing electrophysiological studies at a district general hospital and to evaluate the importance of such studies in the management of patients with suspected arrhythmias. DESIGN: Retrospective study of patients having had electrophysiological studies during a three year period. SETTING: District general hospital. SUBJECTS: 93 patients (50 men, 43 women, mean age 45.9 years) with suspected arrhythmias. RESULTS: The patients were divided into two groups according to symptoms. Group 1 (34 patients) presented with syncope. Group 2 (59 patients) presented with palpitation. All had previously undergone non-invasive investigations. All had had multiple hospital admissions and outpatient attendances. In group 1 nine patients with no documented arrhythmias had inducible ventricular tachycardia and three of six with suspected bradyarrhythmias had ventricular tachycardia. Fourteen patients had suspected ventricular arrhythmias before electrophysiological studies, which were confirmed in all, four receiving automatic implantable cardioverter defibrillators. Electrophysiological studies were used to guide drug treatment in all patients. Group 2 consisted of 32 patients with reentrant supraventricular tachycardia and 15 with ventricular tachycardia; 12 had no documented arrhythmias. In those with supraventricular tachycardia, accessory pathways were identified in all. In 23 patients drug treatment (guided by electrophysiological studies) was successful. In nine, drug treatment guided by electrophysiological studies were ineffective and radiofrequency ablation was successful. In 15 patients with ventricular tachycardia and palpitations, 10 had their drugs changed after electrophysiological studies and their ventricular tachycardia was suppressed. In five patients electrophysiological studies showed that ventricular tachycardia was unsuppressed and they were referred for an operation or implantation of an automatic cardioverter defibrillator. In 12 patients with no documented arrhythmias electrophysiological studies identified significant arrhythmias in six. There were no complications. CONCLUSIONS: Diagnostic electrophysiological studies can safely and effectively be performed in a district general hospital. These studies are especially effective in investigating patients with syncope, and also provide a strategy for future arrhythmia management.

Adolescent↗
PubMed1995

Lung functions in malnourished children aged five to eleven years.

Lung functions including FVC, FEV1, PEFR, %FEV1/FVC and Empey Index were measured using P.K. Morgan's pocket spirometer on 122 children of both sexes in the age group of five to eleven years. There were 80 (65.57%) malnourished children according to the Indian Academy of Pediatrics classification. FVC and FEV1 were significantly (p < 0.02) reduced in malnourished children. FVC (r = 0.67, p < 0.001), FEV1 (r = 0.68, p < 0.001) and PEFR (r = 0.53, p < 0.001) showed linear relationship with body surface area in all age groups. Empey index was less than 10 in both healthy and malnourished children. Abnormal respiratory functions should be interpreted with caution in malnourished children.

Body Surface Area↗
PubMed1994

Correlation of malaria endemicity with An. culicifacies sibling species composition and malaria antibody profile in district Allahabad (U.P.).

Entomological, parasitological and serological surveys were conducted between October 1989 and November 1990 in 27 villages (population 33,250) belonging to three topographically different areas of district Allahabad, viz. Gangapar, Doaba and Yamunapar. A good correlation existed in all the three areas between malaria incidence vis-a-vis An. culicifacies sibling species composition and malaria antibodies titre in the populations. In Gangapar and Doaba villages, An. culicifacies densities were low and the proportions of vector species A and C were much less than that of species B, the non-vector species. Low endemicity of malaria was supported by low antibody titres observed in the population. In contrast, in Yamunapar villages An. culicifacies densities were high, species A and C together were almost equal to species B, and malaria incidence as well as antibody titre were high. Based on these observations, district Allahabad, Uttar Pradesh, could be divided into two zones, low malaria transmission zone--Gangapar and Doaba areas and high malaria transmission zone--Yamunapar area.

Adolescent↗
PubMed1994

Who decides?

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Child Health Services↗
PubMed1993

Determination of quinine in serum, plasma, red blood cells and whole blood in healthy and Plasmodium falciparum malaria cases by high-performance liquid chromatography.

A normal-phase high-performance liquid chromatographic method using dichloromethane-methanol-1 M perchloric acid (100:9:0.4, v/v) at a flow-rate of 0.8 ml/min on a Zorbax-Sil column with fluorescence detection has been developed for the separation of quinine and quinidine from other antimalarials. Within-day and day-to-day coefficients of variation averaged 0.74 and 7.56%, respectively. The extraction recovery of quinine for plasma, serum, red blood cells and whole blood (filter paper) was 88.13, 87.12, 78.0 and 77.5%, respectively. The method is capable of separating quinine from dihydroquinine, a compound usually found as an impurity in authentic quinine samples. The method has been used for the determination of quinine in plasma, serum, red blood cells and whole blood (filter paper) of six healthy and twenty Plasmodium falciparum malaria cases. The average quinine concentration in P. falciparum malaria cases was three to four times higher than that in healthy volunteers. Quinine was absorbed much less in red blood cells than in plasma or serum.

Adult↗