Hypoproteinemia as a prognostic risk factor for arteriovenous fistula failure

Introduction: Any vascular access is of limited duration with many factors which influence survival in patients on chronic hemodialysis (HD). Hypoproteinemia as a marker of chronic illness is common among chronic HD patients. Our aim was to analyze the survival of the primary arteriovenous fistula (AVFs) and the risk factors which influence their patency and to test the hypothesis that patients with normal values of serum proteins have lower risk of AVF failure compared to patients with hypoproteinemia. Methods: Seven hundred thirty‐four consecutive patients were included who underwent creation of an AVF. The patients were prospectively followed‐up for 2 years. Only patients with AVF function after a month from its creation were analyzed. The patients were divided into two subgroups, with normal and low serum protein levels (<65 g/L). Findings: At follow‐up 497 (67.7%) AVFs were still functional while 237 (32.3%) AVFs failed due to thrombosis or stenosis. Serum proteins and AVFs created on the forearm were positive predictors while diabetes was a negative predictor of longer AVF survival (P < 0.001; P = 0.003; P = 0.043). When comparing patients with normal and low serum protein levels (<65 g/L), mean survival time was significantly longer in patients with normal serum levels (P < 0.001). Discussion: In this study, hypoproteinemia was an independent prognostic marker for AVF failure at 2 years. Hypoproteinemia, based on our results, is an independent, more sensitive and prognostic marker of possible vascular access failure than the presence of other common factors which influence shorter AVF survival.     

Splenocaval shunting for alleviation of portal hypertension in a dog: a case report

To demonstrate the usefulness of in vivo 31P nuclear magnetic resonance spectroscopy (MRS) in the diagnosis of ischemic heart disease, major findings from three clinical cardiac MRS investigations performed at our institute are summarized. The first study investigated whether 31P MRS with handgrip exercise testing could detect myocardial ischemia demonstrated by exercise 201Tl scintigraphy. Contrary to findings in normal subjects or patients with fixed thallium defects, the ratio of phosphocreatine (PCr) to ATP decreased significantly during exercise in patients with reversible thallium defects. In the second study, PCr and ATP content was measured by 31P MRS and compared in human myocardium with reversible ischemia or scar diagnosed by exercise thallium scintigraphy. Although the PCr content decreased in patients with either reversible or fixed thallium defects, the ATP content decreased only in the latter group. In the third study, postischemic myocardium with chronic mechanical dysfunction that exhibits recovery after revascularization in left ventriculography was metabolically characterized using quantitative cardiac 31P MRS. Postischemic myocardium with reversible mechanical dysfunction demonstrated reduced PCr but normal ATP content. These results suggest that 31P MRS is a clinically important method both for the detection of myocardial ischemia and in the evaluation of myocardial viability.     

Effect of local medical opinion leaders on quality of care for acute myocardial infarction: a randomized controlled trial

CONTEXT: The effectiveness of recruiting local medical opinion leaders to improve quality of care is poorly understood. OBJECTIVE: To evaluate a guideline-implementation intervention of clinician education by local opinion leaders and performance feedback to (1) increase use of lifesaving drugs (aspirin and thrombolytics in eligible elderly patients, beta-blockers in all eligible patients) for acute myocardial infarction (AMI), and (2) decrease use of a potentially harmful therapy (prophylactic lidocaine). DESIGN: Randomized controlled trial with hospital as the unit of randomization, intervention, and analysis. SETTING: Thirty-seven community hospitals in Minnesota. PATIENTS: All patients with AMI admitted to study hospitals over 10 months before (1992-1993, N=2409) or after (1995-1996, N=2938) the intervention. INTERVENTION: Using a validated survey, we identified opinion leaders at 20 experimental hospitals who influenced peers through small and large group discussions, informal consultations, and revisions of protocols and clinical pathways. They focused on (1) evidence (drug efficacy), (2) comparative performance, and (3) barriers to change. Control hospitals received mailed performance feedback. MAIN OUTCOME MEASURES: Hospital-specific changes before and after the intervention in the proportion of eligible patients receiving each study drug. RESULTS: Among experimental hospitals, the median change in the proportion of eligible elderly patients receiving aspirin was +0.13 (17% increase from 0.77 at baseline), compared with a change of -0.03 at control hospitals (P=.04). For beta-blockers, the respective changes were +0.31 (63% increase from 0.49 at baseline) vs +0.18 (30% increase from baseline) for controls (P=.02). Lidocaine use declined by about 50% in both groups. The intervention did not increase thrombolysis in the elderly (from 0.73 at baseline), but nearly two thirds of eligible nonrecipients were older than 85 years, had severe comorbidities, or presented after at least 6 hours. CONCLUSIONS: Working with opinion leaders and providing performance feedback can accelerate adoption of some beneficial AMI therapies (eg, aspirin, beta-blockers). Secular changes in knowledge and hospital protocols may extinguish outdated practices (eg, prophylactic lidocaine). However, it is more difficult to increase use of effective but riskier treatments (eg, thrombolysis) for frail elderly patients.     

The synergetic effect of learning styles on the interaction between virtual environments and the enhancement of spatial thinking

Students have difficulty learning 3D geometry; spatial thinking is an important aspect of the learning processes in this academic area. In light of the unique features of virtual environments and the influence of metacognitive processes (e.g., self-regulating questions) on the teaching of mathematics, we assumed that a combination of self-regulating questions and virtual environments would enhance spatial thinking through the exercise of certain spatial abilities with the VR Spaces 1.0 software. These two methods primarily focus on the cognitive domain. In terms of learning styles, we define different cognitive characteristics. The main objective of the present study was to examine whether students with a certain learning style would benefit more from this exercise than other students. To assess the effect of these methods, a sample of 192 10th graders were randomly assigned to four groups, two of which used Virtual Spaces 1.0 (Group 1 with virtual reality and self-regulating questions, N = 52; Group 2 with virtual reality only, N = 52) while the other two used non-Virtual Spaces 1.0 (Group 3 with self-regulating questions only, N = 45; Group 4 was the non-treatment group; N = 45). The findings indicate a differential impact of virtual environments on students with different modal and personal learning styles.     

Neurotransmitter interactions in the stomatogastric system of the spiny lobster: one peptide alters the response of a central pattern generator to a second peptide

Two of the peptides found in the stomatogastric nervous system of the spiny lobster, Panulirus interruptus, interacted to modulate the activity of the cardiac sac motor pattern. In the isolated stomatogastric ganglion, red-pigment-concentrating hormone (RPCH), but not proctolin, activated the bursting activity in the inferior ventricular (IV) neurons that drives the cardiac sac pattern. The cardiac sac pattern normally ceased within 15 min after the end of RPCH superfusion. However, when proctolin was applied within a few minutes of that time, it was likewise able to induce cardiac sac activity. Similarly, proctolin applied together with subthreshold RPCH induced cardiac sac bursting. The amplitude of the excitatory postsynaptic potentials from the IV neurons to the cardiac sac dilator neuron CD2 (1 of the 2 major motor neurons in the cardiac sac system) was potentiated in the presence of both proctolin and RPCH. The potentiation in RPCH was much greater than in proctolin alone. However, the potentiation in proctolin after RPCH was equivalent to that recorded in RPCH alone. Although we do not yet understand the mechanisms for these interactions of the two modulators, this study provides an example of one factor that can determine the "state" of the system that is critical in determining the effect of a modulator that is "state dependent," and it provides evidence for yet another level of flexibility in the motor output of this system.     

Designing an Evolutionary Strategizing Machine for Game Playing and Beyond

We have shown that genetically programming game players, after having imbued the evolutionary process with human intelligence, produces human-competitive strategies for three games: backgammon, chess endgames, and robocode (tank-fight simulation). Evolved game players are able to hold their own - and often win - against human or human-based competitors. This paper has a twofold objective: first, to review our results of applying genetic programming in the domain of games; second, to formulate the merits of genetic programming in acting as a tool for developing strategies in general, and to discuss the possible design of a strategizing machine.     

Interaction of hydrogen plasma with carbon-tungsten composite layer

Interaction of neutral hydrogen atoms with the layer of hydrogenated carbon-tungsten composite was studied. A 1 μm thick layer was prepared by sputter deposition from C and WC-targets in Ar/C₂-H₂ gas mixture. After deposition the samples were treated in weakly ionized highly dissociated hydrogen plasma created in a microwave discharge at a power of 1 kW. The gas flow was 13 l/h and pressure was 90 Pa. Temperature of the samples during treatment was about 850 K. After plasma treatment the samples were analyzed by AES (Auger electron spectroscopy) depth profiling, XPS (X-ray photoelectron spectroscopy) and SEM (scanning electron microscopy). It was found that during hydrogen plasma treatment selective etching of the C-W layer occurred. Carbon was preferentially removed from the C-W layer, and after about 10 min of treatment practically only tungsten with a huge porosity was detected.