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Biomedical subjects

S K Bhatnagar

Publications and source records attributed to S K Bhatnagar.

At least 55 records · Page 3Linked to original sources
PubMed1986

Seasonal variation in the incidence of unstable angina and acute myocardial infarction: effect of dry hot climate on the occurrence of complications following acute myocardial infarction.

The incidence of unstable angina (UA) and acute myocardial infarction (AMI), and the occurrence of complications following AMI were studied retrospectively by utilizing data of 7859 patients admitted during three consecutive winter and summer periods from 1979 to 1982. In all patients, UA was more frequent during summer than in winter: 58 out of 3819 (1.5%) versus 37 out of 4040 (0.9%) respectively (P less than 0.05). A similar difference was observed for the incidence of AMI: 183 out of 3819 (4.8%) in summer versus 157 out of 4040 (3.9%) in winter (P less than 0.05). This seasonal variation in the incidence of UA and AMI was significant only in male patients (P less than 0.05). Shock and mortality were higher during summer than in winter in all, and in male AMI patients with or without previous infarction. It is suggested that a hot dry summer is an important risk factor for the occurrence of UA and AMI, and the associated serious complications following the latter in males.

Aged↗
PubMed1985

The role of prehospital discharge two-dimensional echocardiography in determining the prognosis of survivors of first myocardial infarction.

Two-dimensional echocardiography (2DE) was performed in 47 consecutive survivors (mean age 47 years) of a first myocardial infarction (MI), to assess its value in predicting major cardiac complications (MCC) during the posthospital phase. 2DE was undertaken 1 day before hospital discharge (mean 15 days). A wall motion score was derived by analyzing endocardial motion in 11 left ventricular segments. During a mean 17-month follow-up, 17 patients had MCC: eight (47%) had significant angina; two (12%) reinfarcted, and seven (41%) died. Wall motion scores of patients with MCC (9.2 +/- 0.9) (+/- SEM) were significantly higher compared to those without MCC (3.7 +/- 0.4 (p less than 0.005). A wall motion score greater than or equal to 8 was present in 82% (14 of 17) of patients with MCC compared to 7% (2 of 30) who remained asymptomatic. Patients who died had significantly higher wall motion scores compared to those who survived (11.3 +/- 0.9 vs 4.7 +/- 0.5) (p less than 0.005). Stepwise logistic regression and discriminant analysis, by means of age, infarct site, maximal Killip class, cardiac enzymes, and wall motion score, identified wall motion score and Killip class as the most significant predictors of MCC. Thus predischarge 2DE is capable of identifying high-risk patients prone to developing MCC after a first MI.

Adult↗
PubMed1985

Left ventricular thrombosis, wall motion abnormalities, and blood viscosity changes after first transmural anterior myocardial infarction.

Sixty-three consecutive patients with a first transmural anterior myocardial infarction (MI) were studied by serial two-dimensional echocardiography (2D echo) to relate left ventricular (LV) thrombosis with serial changes in blood and plasma viscosity and fibrinogen levels, and wall motion abnormalities at the thrombus site, in order to identify those prone to this complication. The results suggest that an early 2D echo be performed in all patients with acute transmural anterior MI to detect LV thrombi and to identify those at risk of thrombosis.

Adult↗
PubMed1984

The interaction of DNA polymerase III and the product of the Escherichia coli mutator gene, mutD.

A comparison of DNA polymerase III core enzyme (McHenry, C. S., and Crow, W. (1979) J. Biol. Chem. 254, 1748-1753) prepared from wild type Escherichia coli and a strain harboring the mutator gene, mutD5 (Degnen, G. E., and Cox, E. C. (1974) J. Bacteriol. 17, 477-487) has revealed several differences in their properties. Among these are alterations in the heat stability, divalent cation requirement, pH optimum, 3'----5'-single strand exonuclease activity, and DNA-dependent conversion of a deoxynucleoside triphosphate to its corresponding monophosphate ("turnover"). The decrease in the 3'-single strand exonuclease and turnover indicate a defect in the editing function of the mutD strain, which is at least in part responsible for the high spontaneous mutation rate in mutD. Transformation of mutD by a hybrid plasmid, pRD3, constructed from an EcoRI restriction fragment of E. coli and pBR322, cures mutD of its abnormally high mutation rate, and simultaneously restores its 3'-exonuclease activity. These observations are consistent with the notion that the mutD gene product is a subunit of DNA polymerase III, and it either contains the catalytic site for the 3'-exonuclease or modulates its activity. From a consideration of the known molecular weights of the subunits in DNA polymerase III core (McHenry C. S., and Crow, W. (1979) J. Biol. Chem. 254, 1748-1753) the molecular weights of the two proteins translated in maxicells transformed with pRD3, and from a comparison of our results with those obtained with the mutator dnaQ (Horiuchi, T., Maki, H., Maruyama, M., and Sekiguchi, M. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 3770-3774) and the work of Cox and Horner (Cox, E. C., and Horner, D. L. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 2295-2299) as well as Echols et al. (Echols, H., Lu, C., and Burgers, P. M. J. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 2189-2192) we tentatively assign the mutD gene product to the epsilon subunit of DNA polymerase III.

Bacterial Proteins↗
PubMed1984

Significance of early two-dimensional echocardiography after acute myocardial infarction.

We performed serial two-dimensional echocardiography (2D echo) in 35 patients with a first transmural myocardial infarction, to correlate initial left ventricular wall motion abnormalities with subsequent in-hospital cardiac complications, peak total creatine kinase level, and haemodynamic alterations, and to observe serial changes in the left ventricular wall motion. A wall motion score was derived by analysing endocardial motion in 15 left ventricular segments. Left ventricular wall motion could be analysed in 30 patients, 14 without (Group 1) and 16 with complications (Group 2). The initial wall motion score in Group 1 patients was 5.2 +/- 0.7 (+/- SEM) compared to 14.2 +/- 1.2 in Group 2 patients (P less than 0.001). A wall motion score of greater than or equal to 10 correlated with the occurrence of complications in 15 of 16 patients (sensitivity 93%, specificity 92%). Initial wall motion score did not correlate significantly with peak total serum creatine kinase and did not change significantly during the first 72 hr in both the groups. In 12 patients who underwent right heart catheterization together with 2D echo, the average wall motion score was 16.4 +/- 2.0 and cardiac index 2.4 +/- 0.3. Wall motion score correlated inversely with the cardiac index in these patients (r = -0.78; P less than 0.01). Thus, 2D echo performed in first transmural myocardial infarction patients soon after admission can identify those likely to have in-hospital complications. 2D echo wall motion score correlated significantly with the cardiac output in this study.

Adult↗
PubMed1984

Early two-dimensional echocardiography in acute myocardial infarction. A study of left ventricular wall motion abnormalities.

Two-dimensional echocardiography (2DE) was utilized in 49 patients with a first transmural myocardial infarction, within 6 hours (+/- 3SD) after admission and again at 48 hours, in order to correlate initial left ventricular wall motion (LVWM) abnormalities with subsequent in-hospital cardiac complications. Analysis of systolic endocardial motion was made in 15 left ventricular segments in each patient and a total wall motion (WM) score was derived as a measure of the extent of myocardial involvement. LVWM abnormalities in relation to Killip class, peak total serum creatine kinase (CK) and serum glutamic oxaloacetic transaminase (SGOT) enzyme levels were also studied. Adequate echocardiograms for LVWM analysis were obtained in 43 patients. Thirteen patients had no infarct-related complications (group I) and 30 had complications (group II). The mean initial WM score in group I patients was 5.7 +/- 2.6 which was significantly lower than the 13.5 +/- 3.9 in group II (p less than 0.0001). A WM score of greater than 10 correlated with the occurrence of complications in 93% of patients. The WM score was significantly higher in admission Killip class 1 and 2 patients in group II compared with group I patients in class 1. However, no difference was noticed between the mean WM score of patients assigned to these 2 classes in group II. Peak CK and SGOT levels showed a poor correlation with the WM score in group I patients. In group II patients, only the peak SGOT levels correlated significantly with this score. We conclude that in patients with acute infarction, 2DE soon after admission can identify those likely to have in-hospital cardiac complications.

Adult↗
PubMed1983

Left ventricular thrombi after acute myocardial infarction.

Two-dimensional echocardiography was utilized in a prospective study to find the incidence, characteristics and natural history of left ventricular thrombus in 50 consecutive patients with acute myocardial infarction. The overall incidence of thrombosis was 14%; 19% in anterior and 5% in inferior infarction. The thrombus was detected at the apex in 4, along the ventricular septum in 2 and at both these sites in one patient. It was observed 3-10 days after the infarction. Thrombus at the ventricular septum, seen in this study, has not been reported previously in acute myocardial infarction. Development of apical and septal thrombi was significantly associated with akinesis of these sites. Only 2 patients with protruding thrombi had systemic embolism. We conclude that the apex as well as the septum are common sites for thrombosis in patients with severe wall motion abnormalities following acute anterior infarction. Careful observation of these sites during echocardiography may reveal thrombi prone for embolization.

Adult↗
PubMed1982

Subcellular localization of adenylate cyclase of buffalo spermatozoa.

The intracellular localization of adenylate cyclase and 3',5'-cyclic nucleotide phosphodiesterase in buffalo sperm was examined. Adenylate cyclase activity is distributed in heads (8.4%), midpieces (16.6%), tails (49.5%) and 5.7% in the soluble supernatant; the total recovery being 81%. A 4-fold increase in specific activity was observed in the tail fraction relative to sonicated suspension. Further fractionation of the tail fraction into plasma membrane and microtubules by dialysis against low ionic strength buffer was followed by marker enzymes (Mg2+ -ATPase, 5'-nucleotidase and alkaline phosphatase) as well as by examination of fractions under electron microscope. The recovered adenylate cyclase (79%) was found in microtubules (45%) and plasma membrane (34%). Cyclic nucleotide phosphodiesterase in tails was distributed in tail plasma membrane (13.7%), microtubules (31.5%) and cytosol (34%) with a total recovery of 80%. Similar results were obtained when the distribution of adenylate cyclase and cyclic nucleotide phosphodiesterase was studied by treatment with Triton X-100; 40% activity of adenylate cyclase present in tails (about 20% relative to sperm sonicate) appeared in the soluble form by this method. The results are discussed in relation to control of cyclic AMP levels in buffalo sperm by adenylate cyclase and cyclic nucleotide phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Association of cyclic nucleotide phosphodiesterase of buffalo spermatozoa with sperm chromatin.

Buffalo sperm heads contain more than 50% of the total cyclic AMP-phosphodiesterase activity (EC 3.1.4.17) present in spermatozoa. Its distribution in sperm heads revealed no activity in acrosome and other membrane structures present in the head. All the cyclic AMP-phosphodiesterase activity was found firmly bound to sperm chromatin which could not be solubilized. In addition to cyclic AMP, cyclic GMP was also hydrolysed by chromatin preparation. The rate of hydrolysis was 2.5-times more rapid with cyclic AMP than with cyclic GMP at their optimum pH of 7.5 and 8.0, respectively. The pH and heat stability profiles, inhibition studies and the effect of divalent metal ions indicated that the two activities are not associated with the same protein. Mixed substrate analysis showed two sites at which the hydrolysis of cyclic AMP and cyclic GMP is catalysed. Chromatin cyclic nucleotide phosphodiesterases exhibited kinetics typical of one enzyme species both for cyclic AMP (K m = 100 microM; V = 1.0 nmol/min per mg protein) and cyclic GMP (Km = 23 microM; V = 0.4 nmol/min per mg protein). Each cyclic nucleotide was found to be a competitive inhibitor of the hydrolysis of the other with a Ki value of 30.18 microM for cyclic AMP hydrolysis and 256 microM for cyclic GMP hydrolysis. Hill coefficients of 1.0 obtained in the presence of cyclic AMP for cyclic GMP hydrolysis and vice-versa indicated no allosteric interactions. It is suggested that chromatin cyclic nucleotide phosphodiesterase may have a role post fertilization in cell growth and differentiation with no role in sperm motility which is regulated by similar enzymes present in sperm flagella.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1980

Echocardiography in infective endocarditis.

Two cases of infective endocarditis are reported. In both, vegetations on the cardiac valves characteristic of endocarditis were documented by echocardiography and confirmed at surgery in one of them. The various features of vegetative endocarditis on the echocardiogram are described. Differentiation of these echoes from those produced by other morbid states is discussed. Echocardiography is considered a useful non-invasive technique in the diagnosis of infective endocarditis. Cardiac surgery is usually found to be necessary in addition to medical therapy, when echoes characteristic of vegetative endocarditis are recorded by echocardiography.

Adult↗
PubMed1979

Adenosine 3'5'-monophosphate phosphodiesterase of buffalo spermatozoa.

The cyclic AMP-phosphodiesterase (EC 3.1.4.17) of buffalo spermatozoa is distributed in the head, mid-piece and tail fractions and has multiple forms, 70% of which is in the bound form. The bound enzyme was not solubilized by Triton X-100, lubrol or hyamine 2389. Kinetic measurements of the soluble enzyme showed two apparent Km values for low and high cAMP concentrations, i.e. 4.5 and 100 micro M with Vmax values of 0.25 and 2.0 nmol cAMP hydrolysed min-1 mg protein-1. The bound enzyme had an apparent Km of 66.6 microM with a Vmax of 0.75 nmol cAMP hydrolysed min-1 mg protein-1. The pH for optimum enzyme activity was 7.5 and Mg2+ was essential for the activity of the soluble and bound enzymes. Methylxanthines, ATP, ADP and ppi inhibited the soluble and bound enzymes, ATP being the most potent inhibitor.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Studies on the glycosidases of semen: purification and properties of alpha-D-mannopyranosidase from goat seminal plasma.

Alpha D-mannosidase activity in goat semen was observed to be distributed in sperm and seminal plasma. In sperm the enzyme, present in soluble and bound forms, was located within the acrosome. The bound enzyme was associated with the denuded sperm. Seminal plasma alpha-mannosidase was purified 100-fold and the final preparation was shown to be homogeneous by polyacrylamide and SDS gel electrophoresis and on isoelectric focusing. The molecular weight of the enzyme, determined by gel filtration and disc electrophoresis in the presence of SDS, was 220,000. The isoelectric pH was 7.42 and the amino acid composition is reported. alpha-Mannosidase catalyzed the hydrolysis of both synthetic and natural substrates. The Km of p-nitrophenyl alpha-D-mannoside and alpha-methyl D-mannoside were 0.695 mM and 71.9 mM at pH 4.0, the optimum pH. The natural substrates were hydrolysed to varying degrees. Zn2+ was not essential though it activated the enzyme activity over longer incubations. The enzyme was observed to be more stable at wider pH range in the presence of Zn2+ than in its absence. EDTA which did not affect the enzyme activity has effect on enzyme stability similar to Zn.2+ Seminal alpha-mannosidase is not a zinc metalloenzyme but is activated by Zn2+.

Acrosome↗