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Biomedical subjects

R Prasad

Publications and source records attributed to R Prasad.

At least 235 records · Page 13Linked to original sources
PubMed1989

The binding of 3H-(3-MeHis2) thyrotropin releasing hormone to brain and pituitary membranes of morphine tolerant-dependent and abstinent rats.

The effect of chronic administration of morphine and subsequent withdrawal on brain and pituitary receptors for thyrotropin releasing hormone (TRH) was investigated in Sprague-Dawley rats. The rats were implanted subcutaneously with four morphine pellets (each containing 75 mg of morphine free base) during a 3-day period. Placebo pellets, which contained all the excipients of morphine pellets except the morphine, were implanted in rats which served as controls. Both tolerance and physical dependence on morphine have been shown to develop as a result of this procedure. TRH receptors were labeled with 3H-(3-MeHis2) TRH (MeTRH). 3H-MeTRH bound to brain membranes at a single high affinity site with Bmax (receptor density) value of 24.6 +/- 2.2 fmol/mg protein and Kd (apparent dissociation constant) value of 3.7 +/- 0.4 nM. The binding of 3H-MeTRH to five regions of the brain namely, hypothalamus, cortex, striatum, midbrain and pons + medulla, as well as pituitary was also investigated. The binding of 3H-MeTRH to pituitary membranes was increased during the development of tolerance, whereas the binding to membranes prepared from different brain regions was unaffected. Serum concentration of triiodothyronine (T3) and thyroxine (T4) were found to be lower in chronic morphine-treated rats when compared to placebo-treated rats, however, serum TSH level remained unaltered. Twenty-four hours after the removal of morphine pellets (natural withdrawal), the binding of 3H-MeTRH to pons + medulla membranes was greater than in placebo control group. Naloxone-precipitated withdrawal produced results which were qualitatively similar to those obtained in rats from which pellets had been removed. The results suggest that the development of tolerance to morphine may be associated with changes in the pituitary-thyroid axis.

Animals↗
PubMed1989

Predicting relapse in schizophrenia: the development and implementation of an early signs monitoring system using patients and families as observers, a preliminary investigation.

Recognition of prodromal symptoms of schizophrenia offers the potential of early intervention to avert relapse and re-hospitalization (Carpenter & Heinrichs, 1983). The present study investigated how a strategy to detect prodromal signs might be effectively applied in the clinical setting. A standard monitoring system was developed involving completion of a new early signs scale (ESS) measuring changes in key symptoms phenomenologically (self-report) and behaviourally (observer report). The ESS was subject to rigorous psychometric evaluation and tested in a prospective pilot investigation. The ESS reliably identified early signs and predicted relapse with an overall accuracy of 79%. Several different patterns of relapse were identified. Observer reports compensated for loss of insight in some patients. In two cases where early signs indices were detected, prompt increases in medication appeared to arrest relapse and avert readmission. The ESS offers itself as a reliable, valid and administratively feasible measure and demonstrates considerable potential as a cost-effective procedure for secondary prevention.

Adult↗
PubMed1989

Rise in intracellular pH is concurrent with 'start' progression of Saccharomyces cerevisiae.

Intracellular pH (pHi) was determined during arrest and recovery of temperature sensitive-cell division cycle mutants of Saccharomyces cerevisiae. In all mutants, pHi decreased during arrest; but when the mutants were released from arrest a rapid increase in pHi ensued in only cdc28- and cdc37-arrested cells. Both of these mutations cause arrest at 'start', the sole regulatory point in the S. cerevisiae cell cycle. In cells with cdc4 or cdc7 mutations, which arrest past start, pHi remained constant and exhibited a decrease, respectively, upon recovery of growth. The activity of plasma membrane ATPase decreased during the first 30 min of recovery of cdc28-arrested cells, concomitant with the rise in pHi. During the same period, there was no significant change in activity in cdc4-bearing cells, whereas an increase was observed for cdc7-bearing cells. Increase in pHi may be used as a specific signal by S. cerevisiae for start traversal and commitment to a new cycle.

Cell Cycle↗
PubMed1989

Brain and pituitary receptors for thyrotropin-releasing hormone in hypothyroid rats.

The effect of hypothyroidism on the thyrotropin-releasing hormone (TRH) receptors in several brain regions and pituitary of rats was determined. TRH receptors were labeled with 3H-(3-MeHis2)TRH (3H-MeTRH). Hypothyroidism was induced in male Sprague-Dawley rats by administering methimazole (0.05% w/v) in drinking water for 32 days. Rats serving as controls were given water without the methimazole. The development of a hypothyroid state was evidenced by significant decreases in colonic temperature, systolic blood pressure, heart rate and serum concentration of triiodothyronine (total T3), thyroxine and T3 uptake (T3U) as compared to control rats. The rate of gain in body weight of methimazole-treated rats was significantly lower than that of control rats. Binding of 3H-MeTRH at 2 nM concentration to membranes prepared from brain regions (striatum, hypothalamus, cortex, midbrain and pons plus medulla) of methimazole-treated and control rats did not differ. However, binding of 3H-MeTRH to pituitary membranes of methimazole-treated rats was significantly lower as compared to the pituitary of control rats. The results indicate that, in the rat, development of hypothyroidism is associated with down-regulation of pituitary TRH receptors but brain receptors remain unaffected.

Animals↗
PubMed1989

Poor response to long-term albendazole therapy of hydatid liver cysts.

Seven patients with uncomplicated hepatic hydatid cysts (Echinococcus granulosus) were treated with albendazole 10 mg/kg/day for 2-6 months (mean 4 months). Serial sonographic evaluation showed reduction in cyst size in only 1 patient (the anteroposterior diameter decreased from 16.5 cm to 4.9 cm). Therapy in this patient was discontinued after 4 months due to development of jaundice. Albendazole appears to have a limited role in the treatment of hydatid disease of the liver.

Adult↗
PubMed1989

Retinal hemorrhages in newborn--fetal causative factors.

Two hundred and eight alive newborns examined within 2 hours of birth showed 37.50% incidence of retinal hemorrhage (RH). Out of these, 38.59% were full term and 29.17% were preterm. Head circumference had a significant correlation (p less than 0.05) with retinal hemorrhage, while sex of the newborn, birth weight, gestational age and fetal distress showed no significant correlation. Birth injuries especially ocular and periocular injuries showed a significantly higher incidence of retinal hemorrhage (83.33%).

Birth Injuries↗
PubMed1989

Alpha-1-antitrypsin activity in duodenal ulcer.

Alpha-1-antitrypsin activity was estimated in thirty-one duodenal ulcer patients and twenty-five age and sex matched controls. Statistically significant (P less than 0.05) decrease was noted in the mean alpha-1-antitrypsin activity in the patients sera. These observations indicate that alpha-1-antitrypsin deficiency may be one of the important factors in the aetiopathogenesis of duodenal ulcer in a considerable proportion of patients.

Duodenal Ulcer↗
PubMed1989

Relationship between fluidity and L-alanine transport in a fatty acid auxotroph of Saccharomyces cerevisiae.

The influence of the physical state of membrane on L-alanine uptake has been investigated in Saccharomyces cerevisiae KD115, an unsaturated fatty acid auxotrophic mutant. By monitoring the unsaturation index and steady state fluorescence polarization of 1,6 diphenyl hexatriene (DPH), it was observed that at mid log phase the membrane fluidity increased with an increase in the number of double bonds of supplemented fatty acid. Arrhenius plots of the velocities for L-alanine transport in cells grown on palmitoleate, oleate, linoleate and linolenate were biphasic and dependent on supplemented unsaturated fatty acid. Results illustrate a correlation between membrane fluidity and shift in transition points. Further, results confirm the role of fatty acyl milieu in regulation of transport activity of S. cerevisiae.

Alanine↗
PubMed1989

A clinico-bacteriological profile of leprosy in children.

Clinico-bacteriological profile of 106 leprosy patients below 15 years of age was studied. Majority of the patients were males and fell in the 10-15 years age group (p less than 0.01). Nearly 89% had not received any prior treatment because of financial constraints. Seventy per cent gave a positive history of contact with adult patients who were mainly of the lepromatous variety (p less than 0.01). Skin lesions were present in 103 cases, mainly on the exposed areas and their number was found to increase significantly with advancing age (p less than 0.01). These lesions were hypopigmented patches in 71% of the children and erythematous in the rest. Cutaneous sensations were affected in most of the patients while nerve thickening was observed in 45. Positivity of the skin smears increased significantly as the number of skin lesions per patient increased (p less than 0.05). With advancing age, the disease moved from the tuberculoid end of the spectrum towards the lepromatous end (p less than 0.01).

Adolescent↗
PubMed1989

Improvement of myocardial function by trifluoperazine, a calmodulin antagonist, after acute coronary artery occlusion and coronary revascularization.

Activation of an intracellular calcium-calmodulin complex may play an important role in myocardial injury induced by ischemia and reperfusion. Trifluoperazine, a calmodulin antagonist, was used before ischemia to enhance myocardial preservation by preventing intracellular calcium accumulation. The experimental model used an isolated in situ pig heart (19 control animals and 15 trifluoperazine-treated animals) subjected to occlusion of the left anterior descending coronary artery for 60 minutes followed by 60 minutes of hypothermic potassium crystalloid cardioplegic arrest and 60 minutes of reperfusion. Myocardial segmental function measured by ultrasonic crystals showed that active systolic segment shortening was abolished in the distribution of the left anterior descending artery after 60 minutes of occlusion irrespective of the treatment, whereas that not in the distribution of the left anterior descending artery increased by about 15% in both groups of animals. Restoration of systolic segment shortening in the distribution of the left anterior descending artery 60 minutes after reperfusion was 12% and 42% of baseline levels in untreated and trifluoperazine-treated animals, respectively (p less than 0.01). This improvement in segmental function by trifluoperazine was reflected in significantly (p less than 0.05) better global myocardial contractility and compliance and in significantly (p less than 0.01) greater total coronary blood flow and myocardial oxygen consumption. Trifluoperazine also increased myocardial creatine phosphate content in the distribution of the left anterior descending artery (p less than 0.01) during reperfusion, and creatine kinase release was reduced (p less than 0.05). Our results suggest that trifluoperazine improved regional myocardial function after acute occlusion of the left anterior descending artery and reperfusion and that global cardiac performance was thereby improved. The beneficial effects of trifluoperazine may be exerted by prevention of myocardial injury associated with the calcium-calmodulin complex in ischemic and reperfused myocardium.

Adenosine Triphosphate↗
PubMed1988

Dimorphism-associated changes in intracellular pH of Candida albicans.

Intracellular pH (pHi) was monitored during pH-regulated dimorphism of Candida albicans using two different methods: (1) by steady-state distribution of propionic acid and (2) by use of polyene antibiotic, nystatin. There was no significant change in pHi during the first 120 min in either bud- or germ tube-forming populations. However, there was a rapid increase around 135 min which also coincided with the time of evagination. The magnitude of increase in pHi was different in the two populations; being 0.44 and 0.14 pH units in bud- and germ tube-forming populations, respectively. In the two diverging populations, the transient increase in pHi was followed by a rapid drop. The sharp rise in pHi of the population destined to form buds was sensitive to orthovanadate and to the depletion of K+ from the medium while this was not the case with germ tube-forming cells. The results suggest that pHi may play an important role in the phenotypic divergence of C. albicans.

Candida albicans↗
PubMed1988

Long-term bepridil monotherapy for angina pectoris.

The long-term efficacy of bepridil as once-a-day monotherapy was studied in 19 men with stable angina pectoris. After 2 weeks of single-blind placebo therapy and a 12-week parallel placebo-controlled, dose-response study, each patient received open-label bepridil. After a dose-titration period of 3 months, patients received bepridil (100 to 400 mg once a day, mean 290 mg) for 24 months. The response to treatment was assessed by patient diaries and serial treadmill exercise testing 24 hours after dose administration, every 3 months. Only 2 patients were released from the study due to therapeutic failure. Compared with placebo, 3 months of bepridil therapy resulted in a significant reduction in the weekly frequency of angina from 10.3 +/- 9.1 to 1.8 +/- 3.5 (p less than 0.002) and nitroglycerin consumption from 5.0 +/- 5.4 to 1.4 +/- 2.3 (p less than 0.01). In addition, there was a simultaneous significant increase in the walking time to angina from 5.2 +/- 2.3 to 7.9 +/- 2.6 minutes (p less than 0.001) and total exercise time from 7.1 +/- 2.2 to 8.8 +/- 1.9 minutes (p less than 0.001). These favorable effects were sustained throughout the 24 months of the study. Although resting QTc interval was prolonged by 36 to 42 ms (p less than 0.001) during bepridil therapy, ventricular dysrhythmias were not observed immediately before or during exercise testing and were not manifested by symptoms. Neurologic and gastrointestinal side effects of mild to moderate severity were observed, but none required discontinuation of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Radon estimation in some Indian tobacco, tea and tooth powder using CR-39 nuclear track detector.

Radon contents in some samples of tobacco, tea and tooth powder have been estimated using CR-39 solid state nuclear track detectors. The Radon content in tobacco has been found to vary from 14.06 +/- 1.4 to 89.91 +/- 3.3 mBq/l. The Radon content in tea and tooth powder has been found to vary from 27.38 +/- 1.8 to 41.81 +/- 2.2 mBq/l and 26.27 +/- 1.4 to 413 +/- 6.0 mBq/l respectively. The present investigations are useful from the health hazards point of view.

Dentifrices↗