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Biomedical subjects

R Aggarwal

Publications and source records attributed to R Aggarwal.

At least 109 records · Page 6Linked to original sources
PubMed1995

Diminished Ca2+ and Ba2+ currents in myocytes surviving in the epicardial border zone of the 5-day infarcted canine heart.

Ventricular arrhythmias frequently occur in patients suffering from ischemic heart disease. In a canine model developed to understand the pathoelectrophysiological mechanisms of the ischemia-related arrhythmias, electrical stimulation can initiate and terminate reentrant ventricular tachyarrhythmias, which arise in surviving subepicardial muscle fibers (epicardial border zone [EBZ] fibers) of the left ventricle 5 days after coronary artery occlusion. Both the structural and electrical changes occurring in the EBZ provide the important substrate for generation of reentrant ventricular tachyarrhythmias. In this study, we tested the hypothesis that abnormalities exist in the electrophysiological properties of macroscopic Ca2+ currents in myocytes isolated from the EBZ of the 5-day infarcted canine heart (IZs). We recorded the T-type (ICa,T) and L-type (ICa,L) Ca2+ currents by using the whole-cell voltage-clamp technique with either Ca2+ or Ba2+ (5 mmol/L) as the charge carrier and under experimental conditions (Na(+)- and K(+)-free solutions, 10 mmol/L intracellular EGTA) that eliminated contamination by other currents. When Ca2+ served as the charge carrier, the density of peak ICa,T in IZs (0.89 +/- 0.5 pA/pF, n = 28) was similar to that in myocytes from normal noninfarcted hearts (NZs) (1.1 +/- 0.5 pA/pF, n = 32). Although no changes existed in the properties of ICa,T, dramatic changes occurred in the density and function of ICa.L in IZs compared with NZs. Density of peak ICa,L at a holding potential of -40 mV (8-second clamp-step interval) was significantly reduced in IZs (4.6 +/- 1.5 pA/pF, n = 40) compared with NZs (7.2 +/- 1.6 pA/pF, n = 53). The reduction in peak ICa,L density was not attributable to altered steady state inactivation relations or a delay in recovery of ICa,L from inactivation. The time course of decay of peak ICa,: was described by a biexponential function in both cell types, with the fast and slow time constants (tau 1 and tau 2, respectively) of decay being significantly faster in IZs (tau 1 12.3 +/- 3.6 ms; tau 2, 55.1 +/- 31.1 ms) than in NZs (tau 1, 16.1 +/- 4.1 ms; tau 2, 85.2 +/- 51.7 ms). In addition, rapid clamp stimulation (at 1-s intervals) of cells produced a larger frequency-dependent decrease of peak ICa,L density in IZs than NZs, suggesting that at more physiologically relevant rates, little ICA.L may be activated. Finally, a significant reduction and acceleration of decay of the ICa,L persisted even when Ca2+ was substituted by equimolar Ba2+ as the charge carrier.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Assisted ventilation for hyaline membrane disease.

OBJECTIVES: To study the outcome and complications of assisted ventilation in neonates with hyaline membrane disease (HMD). DESIGN: Retrospective study. SETTING: Hospital based. SUBJECTS: Seventy five premature neonates with HMD needing assisted ventilation born over a period of five years. MAIN OUTCOME MEASURES: Survival rate among those ventilated and complications of assisted ventilation. RESULTS: Survival on assisted ventilation improved from initial 22.2% in 1989 to 77.8% in 1993. Of 19 babies weighing between 750-1000 g, 8(42.1%) survived. Twelve of 27 babies (44.4%) with a gestation of less than 28 weeks survived. Survival rates in babies with gestation of more than 33 weeks was 94%. Intraventricular hemorrhage was the leading cause of death in 52% babies. Nosocomial infections were common and occurred in 50.6% of infants on ventilation and accounted for one-third of deaths. Pneumothorax occurred in one-fifth of babies and was responsible for 3 deaths. Pulmonary interstitial emphysems was observed in 6 babies. Six babies developed bronchopulmonary dysplasia while 7 had retinopathy of prematurity. CONCLUSIONS: Outcome of neonates needing assisted ventilation for HMD has shown consistent improvement over the period of study. Nosocomial infections continue to be a major complication of assisted ventilation in neonates.

Cause of Death↗
PubMed1994

The pattern of residual muscle paralysis in poliomyelitis.

Rural schoolchildren between the ages of 6 and 18 years were screened for residual paralysis following poliomyelitis; 503 (0.85%) out of a total of 58,592 were victims. Of these, only 16 (3.8%) had received poliomyelitis vaccine, while the remainder had not been immunised. The disease had occurred before the age of 4 years in nearly 90%, the lower limbs being affected (98%) more often than the upper (2%). In the lower limbs, the quadriceps, hip adductors and tibialis anterior were frequently affected. The muscles supplied by the L4 and L5 spinal segments were most commonly involved, while those supplied by L1 and S3 were least. Some order does exist in the apparently irregular distribution of paralysis after poliomyelitis.

Adolescent↗
PubMed1994

Hepatitis E: intrafamilial transmission versus waterborne spread.

The relative significance of intrafamilial transmission and continued water contamination in the spread of hepatitis E is not known. To resolve this question, two surveys were conducted during a large bimodal waterborne epidemic of hepatitis E in Kanpur, India, affecting an estimated 79,000 persons: i) April 1991: covering 420 houses (60 houses each in seven municipal wards) selected using multistage sampling and random number tables, and ii) May 1992: covering the same families in five municipal wards with incidence rates exceeding 1.5% in the first survey. The number of affected cases in each family and the time of onset of disease in each case were recorded. The time interval between the first ('index') case and the subsequent ('later') case(s) in each family was calculated. The temporal relationship of the occurrence of cases was correlated with the time of control of water contamination. One hundred and eleven hepatitis cases occurred in the 343 families (with 2018 members) studied. Eighty-one of these were single or first cases in their families. Twenty-two 'later' cases occurred within 2 weeks (minimum incubation period of hepatitis E) of the 'index' cases and could not be due to intrafamilial transmission. Thus, 103 of 111 (92.8%) cases were due to primary waterborne infection. Eight 'later' cases (7.2% of 111) that occurred 2-6 weeks after the index cases could be due either to direct spread or to intrafamilial transmission. No 'later' case occurred more than 6 weeks after the 'index' cases. New cases stopped appearing 9 weeks (upper limit of incubation period of hepatitis E) after steps to check water contamination were taken.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Premature infants in car seats: effect of sleep state on breathing.

Previous studies have shown that premature infants may be at risk for hypoxemia and bradycardia when placed in standard car seats. However, the relationship of such breathing abnormalities to sleep state have not been studied. The purpose of the present study was to investigate the effect of car seat positioning on respiratory patterns in preterm infants during sleep and to evaluate their relationship to sleep state. Complete polysomnography, including sleep and breathing parameters, was performed on twenty-eight premature infants. Each infant was randomly assigned to the car seat or prone (crib) position for the first recording period. Following the recording of at least two sleep cycles, the position was reversed. The percentage of active and quiet sleep was calculated and breathing parameters were measured. In the car seat, the infants spent significantly more time in active sleep and less time in quiet sleep than in the prone position, of the respiratory parameters, periodic breathing (PB) was significantly higher in the car seat. The presence of at least one abnormal breathing events (bradycardia, desaturation, PB apnoea) was also significantly higher in the car seat. An analysis of variance (ANOVA) of PB revealed significant sleep-state effect (active vs. quiet sleep), but no significant condition or interaction effects, indicating that PB was more frequent in active sleep regardless of the sleeping condition. It is concluded that increased active sleep in the car seat condition, rather than the positioning of the infant in the seat per se, may account for the increase in periodic breathing and possibly other breathing abnormalities reported in car seats.

Journal Article↗
PubMed1994

Incidence of congenital heart disease among hospital live births in India.

Ten thousand nine hundred and sixty four consecutive live births weighing more than 500 g and more than 28 weeks of gestation were subjected to a thorough clinical examination within 24 h of birth. Those suspected of having congenital heart disease (CHD) were followed up every 4-6 weeks for a period of 6 to 18 months (mean 9.75 months). Forty three of 10,964 infants had CHD, i.e., 3.9/1000 live births. Incidence of CHD was higher in pre-terms as compared to full term live births (22.69 vs 2.36/1000 live births). Diagnosis was confirmed by echocardiography including 2D, Doppler and color flow imaging. Twenty eight per cent of the infants with CHD had other associated somatic anomalies, Down's syndrome being the commonest (9.3%). Patent ductus arteriosus (41.9%) and ventricular septal defects (VSD) (34.9%), were the commonest lesions with an incidence of 1.6 and 1.4/1000 live births, respectively. Incidence of PDA was higher probably because of larger number of pre-term deliveries. During follow up of 6-18 months, 34.9% of the infants with CHD died. The diagnosis of CHD was confirmed at autopsy in 20% of the deaths.

Abnormalities, Multiple↗
PubMed1993

Role of infectious agents in exacerbations of ulcerative colitis in India. A study of Clostridium difficile.

Fifty patients with idiopathic ulcerative colitis--25 with acute exacerbation of the disease (Group I) and 25 in quiescent phase (Group II)--were studied. None of the patients had a history of recent exposure to antimicrobial drugs or hospitalization. Evidence of infection with protozoal and bacterial agents and/or presence of Clostridium difficile toxin was demonstrated in eight (32%) patients in group I and one (4%) patient in group II (group I vs. group II, p < 0.05; chi 2 test with Yate's correction). In five of the six patients with demonstrable Clostridium difficile toxin in the stool, one patient with Entamoeba trophozoites, and another with Salmonella infection, the exacerbation responded clinically and endoscopically to specific antimicrobial therapy. Another two patients who had Entamoeba histolytica cysts in the stool had no change in their clinical status with metronidazole. We conclude that infectious agents are responsible for some of the exacerbations in patients of ulcerative colitis in a tropical country like India, where careful microbiologic examination is in order in every acute exacerbation of this disease. This contrasts with the findings in developed countries.

Acute Disease↗
PubMed1993

Evaluation of phenolic glycolipid-I (PGL-I) antibody as a multidrug therapy (MDT) monitor.

Since phenolic glycolipid-I (PGL-I) is an unequivocal marker for Mycobacterium leprae, this antigen has been a good candidate for the serodiagnosis and monitoring of the effectiveness of leprosy chemotherapy. The present study, a continuation of an earlier report, was undertaken to estimate PGL-I antibody titers in 40 leprosy patients 3 and 6 months after starting MDT. All the leprosy groups showed significant declines in anti PGL-I reactivity after 6 months. There was a good correlation between bacteriological indices (BI) and anti PGL-I antibody levels. Thus, PGL-I based serology may be useful in monitoring the response to multidrug therapy.

Antigens, Bacterial↗
PubMed1993

Conjunctival amyloidosis: is it related to trachoma?

Due to presence of trachoma in a large percentage of cases of conjunctival amyloidosis, trachoma has been blamed for causing secondary localized amyloidosis. However, there is no study to demonstrate evidence of amyloidosis in tarsoconjunctival specimens of trachomatous lids. 50 eyes of 35 patients having trachomatous eyelids with thickened tarsal plate, trichiasis and entropion had a tarsoconjunctival biopsy (3 mm x 20 mm) from the upper lid. Histopathological examination using Haematoxylin--eosin and congo red stains failed to reveal evidence of amyloid deposition in any of the biopsies. This is the first histopathological study of amyloidosis in trachomatous patients. Our study rules out the long-standing concept of trachoma having causal relationship with conjunctival amyloidosis. It is concluded that conjunctival amyloidosis occurring in trachomatous lids should be considered as primary localized amyloidosis.

Aged↗