Search PubMed⌕ Search

Biomedical subjects

M Misra

Publications and source records attributed to M Misra.

At least 127 records · Page 7Linked to original sources
PubMed1988

Preparation and evaluation of technetium-99m labeled cardiac glycoside derivatives as potential myocardial imaging agent.

Three cardiac glycosides, two natural, cymarin and convallotoxin and one synthetic, strophanthidin-beta-D-glucoside were converted to their thiosemicarbazone and subsequently radiolabeled with 99mTc by chelation. The resulting radioactive chelate complexes were evaluated in animals to determine the suitability of this class of compounds for myocardial imaging. It was observed from the animal biodistribution data of the three radioactive compounds, there was a considerable variation in the heart to non-target organ uptake ratio. A possible explanation of this variation was offered in the light of their lipophilic character, protein binding ability and affinity towards non-target receptors. It is anticipated that this study may help to develop a 99mTc-cardiac glycoside complex with better distribution characteristics, and such a compound may offer a suitable alternative to 201Tl, which is at present used for myocardial imaging.

Animals↗
PubMed1988

Jaccoud's arthropathy--diagnostic and therapeutic implications.

A case of isolated chronic severe aortic regurgitation with Jaccoud's arthropathy involving the foot is presented. The interesting feature of the case is the absence of history of acute rheumatic arthritis at any stage of the illness. The diagnostic and possible therapeutic significance of this otherwise uncommon and benign condition are discussed.

Adult↗
PubMed1987

Sinus arrest caused by atenolol-verapamil combination.

A case on concomitant atenolol-verapamil therapy for hypertension and angina pectoris, developing sinus arrest and life-threatening bradycardia is described. The complication occurred with low doses of both the agents and normal electrophysiologic status of the heart. The example suggests that pharmacodynamic synergism contributes more than pharmacokinetic interaction causing adverse reactions during beta blocker-verapamil therapy.

Adult↗
PubMed1987

Value of the treadmill exercise test in asymptomatic and minimally symptomatic patients with chronic severe aortic regurgitation.

The value of the graded treadmill exercise test was assessed in 19 asymptomatic and minimally symptomatic (13 NYHA class I and 6 NYHA class II) male patients with chronic severe aortic regurgitation. It was observed that, in 2 patients who showed significant ST segment depression at peak exercise, the total exercise duration was significantly shorter (P less than 0.001) than in the patients not showing such changes. During left ventricular and aortic root angiography (in both patients) and selective left coronary angiography (in one of them), ST segment changes similar to those seen during exercise testing were observed. The mean rise in left ventricular end-diastolic pressure after injection of contrast material was significantly more (P less than 0.001) in these 2 patients compared to the other 17 patients. Both patients had normal resting M-mode echocardiographic parameters. It is concluded that ST segment depression on exercise testing and reduced exercise capacity are indicants of exercise-induced left ventricular dysfunction in asymptomatic and minimally symptomatic patients with chronic severe aortic regurgitation. Furthermore, it is suggested that this simple and cheap test can be used for serial evaluation of such patients in the absence of the facility of radionuclide cineangiography.

Adolescent↗
PubMed1987

Evaluation of chelating drugs on the toxicity, excretion, and distribution of nickel in poisoned rats.

The effects of various doses of two macrocyclic drugs, namely, 1,4,8,11-tetraazacyclotetradecane (Cyclam) and 5,7,7',12,14,14'-hexamethyl-1,4,8,11-tetraazacyclotetradecane++ + (Cyclam s), on the toxicity, distribution, and excretion of nickel were evaluated in nickel-poisoned rats and compared with the linear counterpart triethylenetetraamine (TETA) and a tripeptide, glutathione (GSH). Cyclam and Cyclam s revealed a higher order of efficacy against the lethal response of nickel even at a lower dose. These drugs significantly enhanced the urinary and biliary excretion of nickel and restored the altered levels of trace metals (viz., Cu, Zn, Fe, Mn) compared to TETA and GSH. The efficacy of these drugs in vivo may be related to their ability to transport nickel across an artificial lipid membrane, a phenomenon was not exhibited by TETA or GSH.

Animals↗
PubMed1987

The pharmacokinetics of enoxacin in elderly patients.

Twenty-three patients of greater than 70 years of age, with proven urinary tract infections were treated with 200 mg of enoxacin twice daily. Serial blood samples were taken on day 1 and peak and trough levels on days 3 and 5. Enoxacin and oxo-enoxacin plasma levels were measured. The mean plasma half-lives of enoxacin and the oxo-metabolite were 6.1 h and 6.7 h respectively. The 2 h plasma level of enoxacin increased from a mean of 1.5 mg/l on day 1 to 2.65 mg/l on day 3 and 2.80 mg/l on day 5. No significant accumulation of the oxo-metabolite (as judged by the 2 h level) occurred. No alteration in enoxacin dosing in the elderly compared with that in younger patients is suggested. Eighty-five per cent of the patients were cured of their infection and no significant adverse advents were noted.

Aged↗
PubMed1987

Development of subaortic stenosis and regurgitation several years after successful operation on a common atrium.

A patient who had had successful operation for a common atrium subsequently developed subaortic stenosis and regurgitation several years later. The diagnosis of subaortic lesion was confirmed by echocardiography. This case shows that the left ventricular outflow tract gradient should be measured before operation for common atrium and that after operation such cases should be examined by cross sectional echocardiography at follow up visits.

Aortic Valve Insufficiency↗
PubMed1986

Two-dimensional structure of phospholipase induced crystals of Ca2+-ATPase from sarcoplasmic reticulum.

A two-dimensional projection map was computed of the Ca2+-ATPase molecules in sarcoplasmic reticulum, isolated from rabbit skeletal muscle. Crystalline arrays of Ca2+-ATPase molecules were formed by incubating the membrane vesicles with phospholipase A2 and dialysing against Tris/HCl buffer. Ca2+-ATPase molecules appear as quasi-triangular blobs in the projection map and seem to form dimers. The projection map seems to indicate an enzyme conformation somewhat similar to vanadate-induced crystals but different from lanthanide-induced crystals of Ca2+-ATPase.

Animals↗
PubMed1986

Preparation and biodistribution of 99mTc chelate of strophanthidin--a cardiac aglycone.

Cardiac glycosides are well known to exert a specific and powerful effect on myocardial tissue, and there is a possibility that this class of compound with a 99mTc radiolabel may behave as a superior myocardial imaging agent in comparison to 201Tl which is at present used clinically. Because of the extreme chemical complexity of cardiac glycosides a simpler aglycone, strophanthidin was selected as the pilot compound for preliminary labelling and in vivo distribution studies. Strophanthidin was converted to 19-thiosemicarbazone which nicely accommodated 99mTc to produce a pure radiopharmaceutical of high specific activity. The distribution pattern in animal models was studied which is in accordance with the metabolic studies performed earlier with the ligand itself.

Animals↗
PubMed1985

Crystallization of Ca2+ ATPase in sarcoplasmic reticulum vesicles by phospholipase treatment.

Ca2+ ATPase molecules in sarcoplasmic reticulum, isolated from rabbit skeletal muscle, have been induced to crystallize into two-dimensional arrays by incubating the vesicles with phospholipase A2 and dialysing against dilute Tris/HCl buffer. These crystals differ in shape and size from those produced by treatment of the sarcoplasmic reticulum vesicles with Na3VO4. However, the unit-cell dimensions of both types of crystals are similar. The differences in shape and size are presumably due to differences in the mechanisms of crystal formation induced by treatment with phospholipase and Na3VO4.

Animals↗
PubMed1985

Assessment of electron irradiation damage to biomolecules using the Patterson function.

A method for the assessment of electron radiation damage to 5-iodouracil is described which involves the use of the Patterson function. Changes in Patterson maps computed from the electron diffraction patterns recorded at increasing electron irradiation have been related to structural and chemical damage to 5-iodouracil. The process of radiation damage is also discussed in terms of a disorder parameter which was found to increase with increasing irradiation.

Mathematics↗
PubMed1985

Effect of thiourea on the testicular steroidogenesis and secondary sexual characters of a tropical freshwater fish, Mystus (M) vittatus (Bloch).

300 ppm of thiourea solution was found to produce significant decline in the interstitial cells of the testes of Mystus (M) vittatus. The regressive changes have been observed both in the number and the size (diameter) of these cells. The thiourea though could not bring about appreciable changes up to the second week, but during third and fourth week marked cellular regression in the interstitial cells has been recorded. Such cellular changes appear to influence the development of the genital papilla and caudal thickening (the secondary sexual characters - SSC) in the male specimens. Changes in the interstitial cells indicative of gonadal steroidogenesis correlated with the SSC is for the first time reported in a tropical fish. Interesting findings have been described and discussed.

Animals↗
PubMed1984

Assessment of electron irradiation damage to biomolecules by electron diffraction and electron energy-loss spectroscopy.

Electron radiation damage is one of the most severe problems in high resolution electron microscopy by biomolecules. The techniques of electron diffraction and electron energy-loss spectroscopy were applied to gain a better understanding of radiation damage in amino acids and nucleic acid bases. The results when compared with G-values for the release of ammonia and hydrogen sulphide from amino acids seem to indicate that bond scission is an important cause of radiation damage at moderate doses of irradiation. High resolution structural disorder in nucleic acid bases was found to involve loss of atoms peripheral to the main ring structure.

Adenine↗
PubMed1984

Correlative changes in the Leydig's cells and male secondary sexual characters (SSC) in a freshwater fish Mystus (M) vittatus.

The study of testicular steroidogenic tissue in the freshwater fish Mystus (M) vittatus has been made by employing histochemical techniques to localize lipids. The Leydig's cells are steroidogenic. Their functional significance has been correlated with secondary sexual characters (SSC). The SSC have been found to follow a clear cut testicular cycle. The development of SSC is reflected by the abundance, numerical variations, size difference, hypertrophy and hyperplasia of the interstitial Leydig's cells. Functional identity of Sertoli cells in the development of SSC seems doubtful.

Animals↗