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Biomedical subjects

K Prasad

Publications and source records attributed to K Prasad.

At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

PISA: a noninvasive method in detection and quantification of acid-induced myocardial infarction in dogs.

Phase invariant signature algorithm (PISA), a new noninvasive technique, was used in the detection and quantification of acid-induced myocardial damage in anesthetized dogs. The diagnostic capabilities of this method were compared with those of conventional electrocardiogram and biochemical markers, MB-creatine phosphokinase (MB-CPK) and lactic dehydrogenase (LDH1). Myocardial damage of varying degree was induced by injecting diluted sulphuric acid (0.01 to 0.10 ml) into the free wall of the left ventricle. Conventional ECG, wideband ECG for PISA analysis, blood samples for LDH1, and MB-CPK were taken before and after 15, 30, 60, and 90 min of acid injection. The heart was removed at the end of 90 min for estimation of myocardial damage. PISA Index increased within 10-15 min of acid injection and remained elevated for the duration of the experiment (90 min). The increase in the PISA index was directly related to the extent of myocardial damage and the amount of acid injected. Although the conventional electrocardiogram detected large myocardial damage, it was unable to detect small myocardial damage. Also, most of initial change in conventional ECG with large myocardial damage disappeared within 90 min, while the PISA index was still elevated to the maximum level. The MB-CPK was not detected before or after myocardial damage. There was no significant change in the LDH1 at any time after myocardial infarction. These results suggest that the PISA technique is superior to the conventional ECG and the biochemical markers and would be a valuable diagnostic tool in the detection and quantification of incipient as well as advanced myocardial infarction.

Animals↗
PubMedDate not supplied

Mediation of H2O2-induced vascular relaxation by endothelium-derived relaxing factor.

We investigated the effects of H2O2 generated by glucose (G) and glucose glucose oxidase (GO) on the isolated rabbit aorta suspended in Krebs-Ringer solution. H2O2 produced contraction in small concentration and relaxation followed by contraction in large concentration. Contraction produced by large concentration was smaller than that produced by small concentration of H2O2. Relaxation was prevented by deendothelialization or NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthesis. These results suggest that H2O2 in large concentrations produces relaxation followed by contraction, and that the relaxation is endothelium-dependent and is mediated by nitric oxide, an endothelium-derived relaxing factor.

Animals↗
PubMedDate not supplied

Randomized, double-blind, placebo-controlled, clinical trial of D-alpha-tocopherol (vitamin E) as add-on therapy in uncontrolled epilepsy.

In a double-blind, cross-over trial, vitamin E, and placebo were compared as add-on therapy in 43 patients with uncontrolled epilepsy. The study consisted of a 3-month baseline period followed by two treatment phases of vitamin E or placebo with cross-over to the second phase after 3 months. No significant side effects were noted during the study. Mean seizure frequency in the baseline period was 15.9 +/- 10.5 as compared with 11.8 +/- 10.9 during the placebo phase and 13.7 +/- 11.1 during the vitamin E phase. No significant change in seizure frequency was observed with vitamin E as compared with placebo (p > 0.1). Similar observation was noted in subgroups with generalized seizures (n = 25), partial with secondarily generalized seizures (n = 11), or complex partial seizures (CPS) (n = 7). This study did not corroborate the earlier claims of therapeutic efficacy of vitamin E as add-on therapy in refractory epilepsy in adults.

Adolescent↗
PubMedDate not supplied

Comparison of the three strategies of verbal scoring of the Glasgow Coma Scale in patients with stroke.

Presence of aphasia in patients with stroke poses a problem in the use of the full form (eye-motor-verbal) Glasgow Coma Scale (GCS). Stroke investigators and clinicians have used three different strategies to deal with the untestable verbal subscale, i.e. eliminating the verbal subscale; pseudoscoring with 'one', and median value substitution; but the predictive accuracy of the strategies has not been compared. To compare the predictive accuracy of the three strategies for acute mortality in stroke, we prospectively applied the GCS to 275 consecutive patients with acute stroke and recorded their survival status before discharge from hospital. 95 (33.8%) patients died. 32 (12%) patients had untestable verbal score. Receiver-Operator-Characteristic curves for predicting mortality were constructed with the GCS sum score and with the multivariate logistic models, and areas under the curves were measured to compare the predictive accuracy. They were all found to be similar (0.87-0.88 sq unit). Specifically, the GCS with eye and motor subscale had 87% accuracy compared to 88% for the model with eye, motor and verbal scale. We conclude that the short-form (eye-motor) GCS is as good a predictor of early mortality (within 2 weeks) as the full form (eye-motor-verbal) GCS in patients with stroke.

Aged↗
PubMedDate not supplied

Cyclofusion in normal and superior oblique palsy subjects.

PURPOSE: To evaluate the cyclofusional status in normal and acquired superior oblique palsy subjects. To know the extent to which cyclodeviations can be tolerated asymptomatically. METHOD: Incyclovergence and excyclovergence break points and recovery points were evaluated in 40 normal subjects and 17 cases of acquired superior oblique palsy. A Polaroid dissociation stereoprojector was used with special torsional slides at fixation distances of 1 meter and 6 meters. In addition, maximum intorsion tolerated (MIT) and maximum extorsion tolerated (MET), ie, the torsion that allowed baseline horizontal fusion, were studied. The evaluation was repeated in the palsy group 1 month after recovery, which was spontaneous in 8 cases, and after surgery in 9 cases. RESULT: The normal values for incyclovergence and excyclovergence were in the range of 12 degrees (break point) and 8 degrees (recovery point). In the case of superior oblique palsy, only the incyclovergence recovery point was significantly diminished (p=.004), which improved after recovery to near normal values. The intorsion tolerance (MIT) and extorsion tolerance (MET) also showed deterioration in the palsy group. After recovery, the MIT normalized but the MET did not recover at 1-meter distance fixation. The maximum torsional tolerance values appear to be more critical. CONCLUSION: The cyclofusional vergence under physiological conditions are better than reported earlier. But MIT and MET are better indicators of cyclofusional potential. These low values demand more precise alignment of the torsion in weakening or strengthening surgery of the oblique muscles.

Eye Movements↗
PubMedDate not supplied

Ionic regulation of peripheral vascular tone and its interaction with norepinephrine.

The effects of various concentrations of K+ (0, 0.5, 1, 2.5, 5, 7.5, 10, 20, and 40 mM) on the tone of femoral arterial strips of rabbit were studied. None of the concentrations of K+ produced relaxation of the arterial strips. Potassium in the concentrations of 10 mM and above produced a concentration dependent increase in the arterial tone. Potassium-induced contraction was dependent upon extracellular Ca++. Norepinephrine (NE) produced contraction in the absence of K+ but the norepinephrine-induced contraction increased with increasing concentration of K+ to a limit. Potassium in lower concentrations (8, 16, 32 mM) accelerated the rate of relaxation of norepinephrine-induced contraction. Verapamil in the concentration of 0.1, 0.5 and 1 microgram/ml produced a concentration dependent inhibition of K+-induced contraction and this inhibition was inversely proportional to the extracellular Ca++. Verapamil in the concentration of 0, 0.1, 0.2, 0.5, 1, 2, 4, 8, and 10 micrograms/ml produced a concentration dependent inhibition of norepinephrine (1 microgram/ml) and potassium (40 mM)-induced contraction. The concentration of verapamil (2 micrograms/ml) which produced 92% inhibition of K+-induced contraction, produced only 48% inhibition of norepinephrine-induced contraction. Even 10 micrograms/ml of verapamil could not block the effect of NE. These results suggest that potassium is not a vasodilator and that there is interaction between K+ and Ca++, and K+ and NE. Ca++ channel blocker has a differential effect on the K+ and NE-induced contraction.

Animals↗
PubMedDate not supplied

Effects of increase in extracellular calcium on frequency-dependent inotropism in cardiac muscle.

Frequency-dependent effects on contractility in isolated rabbit papillary muscles were compared at different calcium concentrations ranging between 1 and 12.5 mM. Increase in extracellular calcium up to 3 mM resulted in an increase in the frequency-dependent positive inotropy. A further increase in extracellular calcium, up to 5 mM, brought about a quantitative decrease in the frequency-dependent positive inotropy. Still higher concentrations of extracellular calcium, 7.5 and 12.5 mM, altogether abolished the frequency-dependent increase in contractility. The latter at these concentrations of calcium was rather depressed in response to frequency increases. These characteristic changes in the frequency-dependent inotropism at different extracellular calcium concentrations may have been due to the occurrence of a moderate to severe intracellular calcium overload. It is suggested that heart function in certain cardiac diseases, associated with intracellular calcium overload, may not improve with an increase in heart rate.

Animals↗
PubMedDate not supplied

Bilateral recurrent laryngeal nerve palsy in systemic lupus erythematosus.

An unusual occurrence of bilateral recurrent laryngeal nerve palsy as an initial manifestation of systemic lupus erythematosus (SLE) is described. The patient had positive lupus anticoagulant (LAC) and high titers of anti-dsDNA antibody. She showed rapid improvement following intravenous pulse dexamethasone.

Adult↗
PubMedDate not supplied

Effect of hydrocortisone on the hemodynamics and serum CK and MBCK enzymes in acute myocardial infarct in dogs.

The effects of hydrocortisone on the hemodynamics and plasma creatine kinase (CK) in dogs with acute myocardial infarction were investigated. Acute myocardial infarction was produced by ligating the anterior descending branch of the left coronary artery and the effects on hemodynamics and plasma CK were observed for two hours. Complete coronary ligation produced a decrease in the cardiac index and left ventricular work index following two hours of coronary ligation. Other hemodynamic parameters (systemic and pulmonary arterial pressure, left ventricular pressure, right atrial pressure, pulmonary arterial wedge pressure, systemic and pulmonary vascular resistance, heart rate, cardiac effort) were essentially unaffected. There was a tendency for an increase in (dp/dt)/IIP but the increase was not significant. In hydrocortisone treated dogs, all the hemodynamic parameters were unaffected except the cardiac index which decreased significantly. Partial coronary ligation produced an increase in the systemic and pulmonary vascular resistance and a decrease in the cardiac index. The other hemodynamic parameters were unaffected. Plasma CK and MBCK increased significantly in dogs with partial or complete ligation of coronary artery. The serum CK was more in partially ligated than in complete coronary ligated dogs. Although hydrocortisone pretreatment decreased the rise of plasma CK it did not change the rise in MBCK observed in coronary ligated dogs without hydrocortisone treatment. These results indicate that hydrocortisone prevents, although not completely, the deleterious effects of ischemia on the plasma CK but has no effect on the increase in plasma MBCK and decrease in the cardiac index.

Animals↗
PubMedDate not supplied

PISA--a noninvasive method in the evaluation of protective effect of methylprednisolone on the ischemic myocardium.

This study deals with the assessment of the PISA--a new noninvasive method, in relation to conventional ECG, MBCPK and LDH1, in the detection and quantification of coronary ligation-induced myocardial damage. Also this study includes the applicability of the PISA method in the evaluation of the effectiveness of methylprednisolone in the protection of myocardial damage, induced by coronary ligation. The studies were conducted in 15 mongrel dogs: (untreated dogs: 9; methylprednisolone (30 mg/kg I.V.) treated dogs: 6). The PISA signature pattern was normal and the PISA index was small in all the dogs before coronary ligation. The PISA signature was phase-variant in all dogs in the untreated group following coronary ligation. The PISA index increased with time following coronary ligation but the changes at 60 minutes were less than at 30 and 120 minutes. There were no significant changes in the conventional ECG, serum MBCPK and LDH1 for the 120 minute duration of coronary ligation. These results indicate the superiority of the PISA method in the detection and quantification of coronary artery ligation-induced myocardial damage. Coronary ligation in methylprednisolone treated dogs produced significant increases in the PISA index with the time but the increases were significantly lower than those in untreated groups. These lower increases at 60 minutes as compared to 30 and 120 minutes observed in the untreated group were absent in the treated group. Methylprednisolone showed some protective effect against coronary ligation-induced myocardial damage. These results indicate that the PISA method may be a valuable tool in the detection and the measurement of the extent of cardiac injury and in constant monitoring of the changes in the size of myocardial damage.

Animals↗
PubMedDate not supplied

Mechanism of cardiac contracture during anoxic arrest using cardiopulmonary by-pass.

Cardiac contracture during anoxic cardiac arrest might result from a reduction in the adenosine triphosphate or from an accumulation of cytoplasmic calcium. The present study was undertaken to test the hypothesis that the accumulation of cytoplasmic calcium is a factor in the anoxic myocardial contracture in a setting similar to that used during cardiac surgery, using cardiopulmonary bypass. Anoxic cardiac arrest was produced for 30 and 60 minutes in 7 dogs each, by clamping the ascending aorta, using cardiopulmonary bypass. At the end of anoxic period, aorta was declamped for reperfusion of the heart for 30 minutes of termination of anoxic cardiac arrest. Total tissue and intracellular electrolytes were determined before and at various intervals (0, 5, 15, 30 minutes) after termination of anoxic cardiac arrest. Thirty minutes of anoxic cardiac arrest produced a significant decrease in the mean aortic and left ventricular systolic pressures, and left ventricular dp/dt/IIP; and a significant increase in the cardiac index. Total tissue and intracellular Na, Ca, and K did not change significantly at the end of 30 minutes of anoxia and during 30 minutes of reperfusion. Anoxic arrest for 60 minutes resulted in cardiac contracture in all dogs. The total and intracellular Ca decreased significantly at the end of 60 minutes of anoxia and during 30 minutes of reperfusion. Total tissue and intracellular Na, although, did not change during anoxic arrest, it increased significantly at 15 and 30 minutes of reperfusion. Cardiac potassium did not change significantly during the whole period of experiment. These studies suggest that total and intracellular calcium did not increase above the control values during anoxic myocardial contracture in a setting similar to that used during cardiac surgery, using cardiopulmonary bypass.

Animals↗