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Biomedical subjects

S Raman

Publications and source records attributed to S Raman.

At least 73 records · Page 4Linked to original sources
PubMed1996

U.S. experience with the AddVent VDD(R) pacing system. AddVent Phase I Investigators.

The AddVent pacemaker generator and model 1328C AV single-pass lead is a new pacemaker system capable of VDD or VDDR modes. The purpose of this study was to present the initial experience with AddVent in the United States and Canada. Between May 10, 1995 and May 3, 1996, 53 devices were implanted in 52 patients and followed for a mean of 217 (+/- 39) days. At the predischarge, 1-, 3-, and 6-month follow-up evaluations, atrial sensing thresholds and ventricular sensing and capture thresholds were measured in the supine, sitting, and standing positions to evaluate stability of atrial sensing with respect to body posture at rest. At the 1-month follow-up, a treadmill exercise test was performed to evaluate atrial sensing during exercise and to evaluate two new features of the AddVent called "sensor-mediated rate smoothing" and "preferential P wave sensing." Atrial sensing thresholds were not significantly different (P > 0.05) among body postures for any follow-up period or among follow-up periods for each posture. At rest, the percentage of appropriately tracked P waves observed was > 99% at each follow-up period. During treadmill exercise, the percentage of appropriately tracked P waves was > 98.7%. Appropriate preferential P wave sensing and sensor-mediated rate smoothing (VDDR mode) was observed. The AddVent pacing system provides safe and effective pacing therapy. Several features of VDDR pacing offer advantages over standard VDD pacing.

Aged↗
PubMed1996

CFTR chloride channel activation by genistein: the role of serine/threonine protein phosphatases.

We have previously shown [B. Illek, H. Fischer, G. F. Santos, J. H. Widdicombe, T. E. Machen, and W. W. Reenstra, Am. J. Physiol. 268 (Cell Physiol. 37): C886-C893, 1995] that genistein, a tyrosine kinase inhibitor, activates the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel in NIH/3T3 cells that have been stably transfected with an expression vector for the CFTR (NIH-CFTR cells). In this study, we present evidence suggesting that both genistein and the serine/threonine protein phosphatase (PPase) inhibitor calyculin A activate the CFTR by inhibiting PPase activity. As measured by 125I efflux, genistein and calyculin A stimulate the CFTR to approximately 50% of the maximal activity with forskolin. Neither agonist increases CFTR activity at saturating forskolin concentrations, but genistein and calyculin A have an additive effect on CFTR activity. Forskolin, but neither genistein nor calyculin A, stimulates protein kinase A(PKA) activity. The PKA inhibitor H-89 inhibits CFTR activation and in vivo phosphorylation by all three agonists. Proteolytic digestion of in vivo phosphorylated CFTR suggests that the CFTR is phosphorylated on the same sites during stimulation with genistein and forskolin but on different sites stimulation with calyculin A. The data suggest that genistein and calyculin A inhibit different PPase activities, allowing CFTR phosphorylation and partial stimulation, by a basal PKA activity.

3T3 Cells↗
PubMed1995

Effect of amlodipine, atenolol and their combination on myocardial ischemia during treadmill exercise and ambulatory monitoring. Canadian Amlodipine/Atenolol in Silent Ischemia Study (CASIS) Investigators.

OBJECTIVES: This study compared the effects of amlodipine, atenolol and their combination on ischemia during treadmill testing and 48-h ambulatory monitoring. BACKGROUND: It is not known whether anti-ischemic drugs exert similar effects on ischemia during ambulatory monitoring and exercise treadmill testing. METHODS: Patients with stable coronary artery disease and ischemia during treadmill testing and ambulatory monitoring were randomized to receive amlodipine (n = 51) or atenolol (n = 49). Each group underwent a counterbalanced, crossover evaluation of single drug and placebo, followed by evaluation of the combination. RESULTS: Amlodipine and the combination prolonged exercise time to 0.1-mV ST segment depression by 29% and 34%, respectively (p < 0.001) versus 3% for atenolol (p = NS). During ambulatory monitoring, the frequency of ischemic episodes decreased by 28% with amlodipine (p = 0.083 [NS]), by 57% with atenolol (p < 0.001) and by 72% with the combination (p < 0.05 vs. both single drugs; p < 0.001 vs. placebo). Suppression of ischemia during exercise testing and ambulatory monitoring was similar in patients with and without exercise-induced angina. Exercise time to angina improved by 29% with amlodipine (p < 0.01), by 16% with atenolol (p < 0.05) and by 39% with the combination (p < 0.005 vs. placebo, atenolol and amlodipine). In patients with angina, total exercise time improved by 16% with amlodipine (p < 0.001), by 4% with atenolol (p = NS) and by 19% with the combination (p < 0.05 vs. placebo and either single drug). In those patients without angina, no therapy significantly improved total exercise time. CONCLUSIONS: Ischemia during treadmill testing was more effectively suppressed by amlodipine, whereas ischemia during ambulatory monitoring was more effectively suppressed by atenolol. The combination was more effective than either single drug in both settings.

Amlodipine↗
PubMed1995

Intravaginal misoprostol for termination of midtrimester pregnancy.

Misoprostol seems to be a drug with many potential uses apart from the treatment of gastric and duodenal ulcers. The oral tablet appears to be effective for termination of midtrimester pregnancy when administered intravaginally. Further research should be carried out to determine its full range of action in order that the drug can be utilized to its maximum potential.

Abortion, Induced↗
PubMed1994

Keratocyte loss after different methods of de-epithelialization.

PURPOSE: To evaluate the response of corneal stromal cells to different types of superficial injury. METHODS: Twenty-two rabbits were randomized into five groups of four (with 2 untreated controls), and their corneas de-epithelialized (1) with a blunt instrument alone; (2) with an instrument and application of 100% ethanol, 0.5% proparacaine, or 4% cocaine; or (3) with the excimer laser. Twenty-four hours after surgery, the eyes were enucleated, and histologic changes were quantitated. RESULTS: All the methods of de-epithelialization used resulted in a decrease in the number of keratocytes relative to the control numbers (P = 0.0001). There is a significantly greater decrease in keratocyte counts with 0.5% proparacaine and 100% ethanol when compared with eyes injured by mechanical means, with 4% cocaine, or with the excimer laser (P = 0.009). All treatment groups showed more polymorphonuclear leukocytes than did controls (P < 0.0001). Mechanical de-epithelialization alone or in conjunction with proparacaine produced the least inflammatory response, but de-epithelialization with the laser was associated with a greater inflammatory response (P < 0.0001). CONCLUSIONS: All methods of de-epithelialization produced a significant decrease in rabbit cornea stromal keratocytes 24 hours after injury, associated with acute inflammation. Thus, it may be appropriate to avoid using chemicals, or if chemicals are used, to at least avoid using 100% ethanol. The applicability of these findings to humans has not yet been established.

Animals↗
PubMed1993

A randomized, controlled trial of radiograph ordering for extremity trauma in a pediatric emergency department.

STUDY OBJECTIVES: The objectives of this study were to determine whether triage nurses using the Brand protocol would order fewer radiographs than would physicians carrying out standard practice procedures, without missing an increased number of joint or bone injuries; the test characteristics and the interobserver reliability of the Brand protocol; and whether having triage nurses order radiographs could reduce total patient waiting time in the emergency department. DESIGN: Randomized, controlled trial. SETTING: The ED of a free-standing children's hospital with approximately 55,000 visits annually. TYPE OF PARTICIPANTS: Children less than 18 years of age who had a history of extremity trauma in the preceding seven days. INTERVENTIONS: Triage nurses applied the Brand protocol to determine the need for a radiograph. MEASUREMENTS AND RESULTS: Of the Brand protocol group, 81.9% had radiographs ordered compared with 87.1% of the control group (P = .03). The percent of positive radiographs was 40.8% in the Brand protocol group compared with 42.6% in the control group (P = .21). There were 3.2% (16) missed radiographic findings in the Brand protocol group compared with none in the control group (P < .001). Patients randomized to the Brand protocol group spent 3.3 hours in the ED compared with 3.6 hours for the control group (P < .001). CONCLUSION: Having triage nurses use the Brand protocol reduced the number of radiographs ordered but at the same time increased the number of missed radiographic findings. However, having triage nurses order radiographs also significantly shortened waiting time in the ED.

Adolescent↗