Continued development of the Nimbus/University of Pittsburgh (UOP) axial flow left ventricular assist system

Nimbus and the University of Pittsburgh (UOP) have continued the development of a totally implanted axial flow blood pump under the National Institutes of Health (NIH) Innovative Ventricular Assist System (IVAS) program. This 62 cc device has an overall length of 84 mm and an outer diameter of 34.5 mm. The inner diameter of the blood pump is 12 mm. It is being designed to be a totally implanted permanent device. A key achievement during the past year was the completion of the Model 2 pump design. Ten of these pumps have been fabricated and are being used to conduct in vitro and in vivo experiments to evaluate the performance of different materials and hydraulic components. Efforts for optimizing the closed loop speed control have continued using mathematical modeling, computer simulations, and in vitro and in vivo testing. New hydraulic blade designs have been tested using computational fluid dynamics (CFD) and flow visualization. A second generation motor was designed with improved efficiency. To support the new motor, a new motor controller fabricated as a surface mount PC board has been completed. The program is now operating under a formal QA system.     

Mechanism of cardiovascular actions of the chromogranin A fragment catestatin in vivo

Catestatin (bovine chromogranin A(344-364); RSMRLSFRARGYGFRGPGLQL), reduces catecholamine secretion from chromaffin cells in vitro. We investigated the effects of this peptide on catecholamine release and blood pressure in vivo. Intravenous catestatin reduced pressor responses to activation of sympathetic outflow by electrical stimulation in rats, and the catestatin effect persisted even after adrenergic (alpha plus beta) blockade. Catestatin did not alter plasma norepinephrine levels, but increased plasma epinephrine 11-fold. Catestatin also blunted pressor responses to exogenous neuropeptide Y agonists. A control peptide (chromogranin A(141-160)) did not alter pressor or catecholamine responses to electrical stimulation. Pretreatment with a histamine H1 receptor antagonist blocked both the vasodepressor response to catestatin and the elevation in plasma epinephrine. Catestatin elevated endogenous circulating histamine 21-fold, and exogenous histamine mimicked both the epinephrine elevation and the vasodepressor actions of catestatin. We conclude that catestatin is a potent vasodilator in vivo whose actions appear to be mediated, at least in part, by histamine release and action at H1 receptors.     

Microbial resistance: what is to be done? Information from the panel of experts

This document represents the recommendations of a panel of Spanish experts on antibiotic use and resistance. In a Task Force, under the auspices of the Spanish Ministry of Health and Consumer Affairs that took place in 1994 in Madrid, the members were gravely concerned about the national increase in antibiotic resistance. They analysed the development, evolution and spread of antibiotic resistance among community-acquired human bacterial pathogens in Spain, its relation with antibiotic consumption, and they proposed future surveillance strategies for monitoring the patterns of antibiotic use and consumption. Success will require a collective action among the producers (pharmaceutical industry), prescribers (doctors, veterinarians), dispensers (pharmacists), and consumers (patients). Two similar documents have been recently published by the American Society of Microbiology and the World Health Organization showing the global concern about this topic.     

Does arterial revascularization decrease the risk of infarction after coronary artery bypass grafting?

BACKGROUND: This study sought to determine whether extensive arterial grafting reduces the prevalence and consequences of infarct after coronary artery bypass grafting. METHODS: Post-primary coronary artery bypass grafting infarcts and time-related events thereafter were identified by 99.9% complete follow-up of 9,600 patients (1971 to 1992). The contribution of arterial grafting to freedom from infarct was assessed by multivariable hazard function analysis to adjust for other risk factors. RESULTS: Unadjusted 1-month and 10-year freedom from infarction was 97% and 86%. By multivariable analysis, arterial grafting lowered the prevalence of periprocedural (p = 0.005), intermediate term (p = 0.007 and 0.006), and late infarction (arterial grafting to the left anterior descending coronary artery, p = 0.0006). Unadjusted survival after first infarct after coronary artery bypass grafting was 74% and 52% at 1 and 10 years; arterial grafting improved 10-year survival from 48% to 59% (p = 0.002). An additional benefit or cost of extending arterial grafting (n = 1,727) beyond a single one could not be identified (p > 0.1). CONCLUSIONS: Arterial conduits, particularly to the left anterior descending coronary artery, should be used for coronary artery bypass grafting to reduce early and late myocardial infarction and its consequences. However, use of more than a single arterial graft appears to confer no additional benefit.     

Relation between intracarotid amobarbital memory asymmetry scores and hippocampal sclerosis in patients undergoing anterior temporal lobe resections

The intracarotid amobarbital procedure (IAP) is used to evaluate memory function preoperatively in candidates for anterior temporal lobe resections (ATL). We examined IAP memory asymmetry scores in 30 patients undergoing ATL (17 R, 13 L), as a function of the presence (HS+) or absence (HS-) of hippocampal sclerosis. Ictal onset zones were determined by extraoperative recording with subdural strip electrodes in all but 3 patients in whom magnetic resonance imaging (MRI) scan showed HS. MRI scans were otherwise normal. All patients were left hemisphere dominant for language except 1, in whom language was represented bilaterally. IAP memory testing involved presentation of eight subjects during anesthesia of each hemisphere, followed by recognition testing after patients recovered from amobarbital effects. A score of 1 was given for each correctly recognized object, and 0.5 was deducted for each false-positive identification. There were 16 foils. A total asymmetry score was calculated, which was positive if there was agreement between the direction of the symmetry and side of operation and negative if reversed. The mean asymmetry score for HS- (n = 8) was 0.9; that for HS+ (n = 22) was 4.1 (p < 0.01). IAP memory performance provided lateralizing information (asymmetry score > or = + or -2) in 73% of cases; among these, the lateralization was correct in 91%. Our data indicate that IAP memory asymmetry predicts both laterality of ictal onset and the presence of HS.