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R Sarma

Publications and source records attributed to R Sarma.

36 records · Page 2Linked to original sources
PubMed1980

Preliminary crystallographic data for protein S, a development-specific protein of Myxococcus xanthus.

Protein S, which is produced only during the developmental cycle of Myxococcus xanthus, has been crystallized using 2-methyl-2,4-pentanediol as a precipitating agent. The crystals were very stable in the x-ray beam for up to 150 h and diffracted to a resolution of 2.2 A. The crystals belong to the orthorhombic space group P212121 with unit cell dimensions a = 52.99 A, b = 60.10 A, and c = 102.16 A. Each asymmetric unit consists of two monomers of Protein S, each having a molecular weight of 23,000.

Bacterial Proteins↗
PubMed1980

Clinical experience with the Kay-Shiley mitral valve prosthesis: an eleven-year follow-up study.

A total of 63 patients, who survived mitral valve replacement with the Kay--Shiley caged disc mitral valve prosthesis, were followed for 11 years by single clinic group to assess long-term results post valve replacement. Sixty-one patients (97%) received a muscle guard type Kay--Shiley prosthesis. All patients received oral anticoagulation therapy. The valvular damage was caused by rheumatic disease in 51 patients, infectious endocarditis in six patients, myxomatous degeneration in two patients, coronary artery disease in two patients, and idiopathic ruptured chordae tendineae in two patients. Late death occurred in 21 patients (33%); the 10-year actuarial survival was 65%. Twenty-six patients had at least one thromboembolic event, and the total number of thromboembolic events was 10.3 per 1000 patient months. Two patients developed prosthetic valve endocarditis. Both patients were heroin addicts and died of valve ring abscess. Long-term periods of clinical observation are necessary to assess the effects and benefits of prosthetic valve implantation. These data are important for comparison with other "10-years" valves.

Adult↗
PubMed1979

Structure of Streptomyces erythraeus lysozyme at 6 A resolution.

A 6 A resolution electron density map has been calculated for a bacterial lysozyme produced by Streptomyces erythraeus. This lysozyme differs from the vertebrate lysozyme in its size, amino acid composition, and specificity. The structure was determined by the method of isomorphous replacement. Three heavy atom derivatives were obtained by soaking crystals of the lysozyme in HgCl2, K2PtCl4, and UO2(NO3)26H2O. The resulting electron density map clearly shows the molecular boundary. The molecule is ellipsoidal in shape with average dimensions 50 A X 35 A X 35 A. High resolution analysis and sequence analysis of the molecule are in progress.

Mercury↗
PubMed1977

Clinical experience with the Smeloff-Cutter aortic valve prosthesis: an 8-year follow-up study.

A total of 46 patients who survived aortic valve replacement with the present model Smeloff-Cutter prosthesis between 1968 and 1973 were followed up postoperatively. All patients received oral anticoagulant therapy. The average age at implantation was 44 +/- 13 (mean +/- standard deviation) years; 36 patients were male and 10 were female. The valve damage was caused by rheumatic disease in 19 (41 percent), infective endocarditis in 14 (30 percent), congenital heart disease in 7 (15 percent) and other factors in 6 (13 percent). Late death occurred in eight patients (17 percent). All available patients were followed up until December 1976. During the 8 years of follow-up study, seven patients, including four heroin addicts, had postoperative endocarditis (15 percent); five of the seven had cerebral involvement, possibly from septic emboli. Four patients were reoperated on; three had active endocarditis and one had a high transvalve pressure gradient. The mean follow-up time was 4.9 years per patient. Of the 38 living patients, 33 have functional improvement and are still being followed up. Only one patient had a bland embolism to a systemic artery. No ball variance or other types of material failure have been detected. Although the chronic aspects of valve disease remain after prosthetic valve replacement, the Smeloff-Cutter aortic prosthesis deserves strong consideration when selecting a rigid prosthesis for aortic valve replacement.

Adult↗
PubMed1976

Assessment of clinical laboratory techniques in the measurement of oxygen saturation in whole blood.

The accuracy and advantages of determining percentage of hemoglobin oxygen saturation of whole blood by advanced instruments of oximetry, gas chromatography, and the computation of oxygen saturation from pO2 and pH data are compared with the Van Slyke-Neill manometric method. It was found that oximetry is extremely fast, less expensive, and more accurate than in the past, the apparatus requires little training to operate and has diminutive service maintenance. The gas chromatograph proved to be highly accurate and could serve as a standard calibration check method in place of the more time-consuming Van Slyke-Neill apparatus for oximetry and pO2 and pH electrode instrumentation. Computation of O2 saturation from pO2 and pH data also proved to be accurate, confirming that this method is more useful during cardiac surgery because it can provide additional acid-base information. In the low oxygen saturation range (less than 60%), all three methods proved to be of similar sensitivity.

Chromatography, Gas↗
PubMed1975

Blood flow velocity in the carotid artery as a measure of myocardial contractility.

An attempt was made to derive a useful noninvasive index to evalute a change in myocardial contractile state using transcutaneous Doppler flow-velocity curve from the carotid artery. In 5 mongrel dogs and in 43 patients with various heart disease, Doppler flow velocity curves were obtained from the ascending aorta intravascularly using a Doppler catheter and/or from carotid artery transcutaneously using a Doppler probe. The first derivative of left ventricular pressure (dp/dt) and electrocardiogram (ECG) were recorded simultaneously. The following 3 indices were measured from the Doppler flow-velocity curves: (1) macimum acceleration of blood flow (dv/dt), (2) time from onset of ejection to peak flow (time-to-peak), (3) time interval between the beginning of Q wave of ECG to the peak of Doppler flow velocity curve (ECG Q-Doppler peak). Among these 3 indices, only ECG Q-Doppler peak demonstrated a significant correlation between the values measured intravascularly and transcutaneously. Also, only ECG Q-Doppler peak showed significant correlation with maximum of dp/dt (max dp/dt). Since ECG Q-Doppler peak showed correlation with heart rate, the difference between observed and predicted ECG Q-Doppler peak (delta ECG Q-Doppler peak) was calculated to exclude the effect of heart rate. Predicted value of ECG Q-Doppler peak was calculated from the regression equation between heart rate and ECG Q-Doppler peak in the separate experiments. There was significant correlation between delta ECG Q-Doppler peak and max dp/dt. In 15 patients with coronary artery disease and in 16 healthy subjects, delta ECG Q-Doppler peak and the other noninvasive method (systolic time intervals) were measured. Delta ECG Q-Doppler peak showed better result in the separation of 2 groups than by systolic timeintervals. It was concluded that delta ECG Q-Doppler peak is a useful index to evaluate the myocardial contractile state since this index is readily obtained noninvasively.

Adolescent↗
PubMedDate not supplied

Quartz crystal microbalance measurement of self-assembled micellar tubules of the amphiphilic decyl ester of D-tyrosine and their enzymatic polymerization.

Amphiphilic decyl derivatives of D-tyrosine self-assemble into long rodlike or tubular aggregate structures in aqueous buffered solution. In this report we demonstrate the novel use of the quartz crystal microbalance (QCM) to measure the presence in solution, and subequent enzymatic polymerization, of long rodlike monomer aggregates of the decyl ester of D-tyrosine (DEDT) as a function of their formation and increasing surface binding level as pH values increase from 3 to 7. From these data, using the Sauerbray equation to calculate the effective elastic mass surface binding of deprotonated DEDT aggregates, a pKapp of 8.3 is obtained for the DEDT alpha-NH2 group protonation-deprotonation and subsequent aggregation equilibrium. Furthermore, once aggregates are bound to the QCM surface, we initiate and subsequently monitor enzymatic polymerization of the DEDT monomers by horseradish peroxidase through the measurement of significant changes in the quartz crystal frequency and motional resistance. Following the onset of polymerization, the viscoelastic properties of the bound monomer aggregates change. A final polymerized state is achieved in which the altered physical properties of the polymerized rodlike aggregates make the solution immediately above the QCM surface-solution interface behave as a Newtonian fluid, producing a nearly pure viscosity-density energy dissipative effect on the measured crystal frequency and motional resistance values.

Biotechnology↗