MB Levels Research Articles

Postmortem cardiac troponin I and creatine kinase MB levels in the blood and pericardial fluid as markers of myocardial damage in medicolegal autopsy

The present study investigated cardiac troponin I (cTnI) and creatine kinase MB (CK-MB) in the blood and pericardial fluid from medicolegal autopsy cases ( n = 234, within 48 h postmortem) with regard to the cause of death. The cTnI and CK-MB levels in cardiac, peripheral blood and pericardial fluid generally showed a mild and gradual postmortem time-dependent elevation ( r = 0.231–0.449, P < 0.05–0.001). However, postmortem elevation of cTnI was larger for specific causes of death including acute myocardial infarction (AMI), cerebrovascular diseases (CVD), hyperthermia, fatal methamphetamine (MA) abuse and carbon monoxide (CO) intoxication and insignificant for recurrent myocardial infarction (RMI), chronic congestive heart diseases (CHD) and drowning, while that of CK-MB was greater for CO intoxication and insignificant for drowning. Cardiac blood and pericardial cTnI levels were relatively high for AMI, RMI, hyperthermia, MA abuse and CO intoxication, and was low for drowning. Elevated CK-MB level was observed for cardiac blood in asphyxiation and MA abuse cases and for peripheral blood in hyperthermia and MA abuse cases. When the cTnI/CK-MB ratio was estimated, it was independent of postmortem time, and the ratios for cardiac blood and pericardial fluid were significantly higher in cases of AMI, RMI, hyperthermia and CO intoxication but lower in cases of drowning. Elevations of cTnI levels in cardiac blood and pericardial fluid were related to the morphological severity of myocardial damage. These findings suggest that elevated cTnI and CK-MB levels in blood and pericardial fluid are related to ischemic, hypoxic and/or cytotoxic myocardial damage, which are characteristic of the cause of death, although the levels increase after death depending on myocardial damage at the time of death.

The effect of mannitol on oxygenation and creatine kinase MB release in patients undergoing multivessel off-pump coronary artery bypass surgery

Despite avoiding cardiopulmonary bypass, off-pump coronary artery bypass surgery is associated with reduction in PaO2 and postoperative respiratory compliance. Also, transient interruption of coronary flow is necessary during distal anastomoses and may impose ischemia-reperfusion myocardial injury. Mannitol is an osmotic diuretic with free radical scavenging properties, and we have evaluated the effects of mannitol on oxygenation and cardiac enzyme release in patients undergoing multivessel off-pump bypass surgery in a prospective, randomized, controlled, double-blind trial. Fifty patients were randomly allocated to receive either 20% mannitol 0.5 g/kg (n = 25) or normal saline 2.5 mL/kg (n = 25) during Y-graft construction. Pulmonary variables and serum sodium concentrations were measured 15 minutes after induction of anesthesia and sternum closure. Creatine kinase MB was measured before and after the operation. Intraoperative and postoperative fluid input and output, time to extubation, and intraoperative hemodynamic variables were also recorded. PaO2 after sternum closure was significantly higher in the mannitol group, with faster time to extubation and shorter length of stay in the intensive care unit. Intraoperative urine output was significantly greater in the mannitol group, without significant differences in fluid input, serum sodium concentration, and hemodynamic variables. Number of patients with a creatine kinase MB level more than 3 times the upper limit of normal was significantly higher in the control group. Mannitol could be safely used without adverse side effects in patients undergoing multivessel off-pump bypass surgery with beneficial effects in terms of preserving oxygenation, earlier extubation, and fewer patients with significant creatine kinase MB elevation.

Trimetazidine Administration Minimizes Myocardial Damage and Improves Left Ventricular Function after Percutaneous Coronary Intervention

The aim of this study was to evaluate whether the administration of trimetazidine, a piperazine derivative, to patients before and after percutaneous coronary intervention (PCI) minimizes the PCI-induced myocardial damage and improves left ventricular function 1 and 3 months after the procedure. Fifty-two patients hospitalized for acute coronary syndromes (ACS) were included in this study. Patients were randomized into two groups: group A (trimetazidine group; n = 27) and group B (placebo group; n = 25). All patients received conventional antianginal therapy. In addition, group A patients received oral trimetazidine 20 mg every 8 hours, starting 15 days before PCI and continuing for 3 months after the procedure. For each patient, serum troponin I and creatinine kinase (CK)-MB levels were measured before PCI, then at 6, 24, and 48 hours after the procedure; a 2D cardiac echocardiogram was performed before PCI and at 1 and 3 months after the procedure. Twenty-four hours after PCI, troponin I levels were >1 ng/mL in 7 of 27 patients (26%) of group A and 11 of 25 patients (44%) in group B. Fourty-eight hours after revascularization troponin levels remained elevated in 15% of patients in group A and in 32% of patients in group B. Twenty-two percent of patients in group A had CK-MB levels >5 ng/mL, 24 hours after PCI, compared with 40% of patients in group B; four patients of group A had high CK-MB levels prior to PCI procedure. Echocardiographic measurements before revascularization revealed that 11 of 27 patients (40%) in group A had an ejection fraction <50% versus 8 of 24 patients (33%) in group B . The number of patients with an ejection fraction <50% was significantly reduced in group A compared with group B at 1 and 3 months after PCI, i.e. 11% versus 16% (p = 0.046) at 1 month and 4% versus 16% (p = 0.017) at 3 months.A significant improvement in regional wall motion was noted after treatment with trimetazidine compared with placebo. One month after PCI, inferior left ventricular (LV) wall hypokinesia had improved in 4 of 6 trimetazidine recipients and in 4 of 14 placebo recipients (p = 0.014, group A vs group B). After 3 months inferior wall hypokinesia improved in four patients in group A versus six patients in group (p = 0.05). Similarly, anterior LV wall motion improved in 3 of 11 patients in group A and in 1 of 6 patients in group B at 1 month. After 3 months anterior wall hypokinesia had improved in eight patients in group A and in two patients in group B (p = 0.04, group A vs group B). The metabolic agent trimetazidine appears to minimize myocardial reperfusion injury during PCI and improves global and regional wall motion at 1 and 3 months after PCI. This study was limited by small patient numbers and further studies are necessary to evaluate exact mechanisms of action and clinical implications of using trimetazidine in conjunction with PCI.

Effect of intravenous N-acetylcysteine on outcomes after coronary artery bypass surgery: A randomized, double-blind, placebo-controlled clinical trial

N-acetylcysteine, a potent anti-inflammatory and antioxidant agent, is known to decrease the production of reactive oxygen species after cardiac surgery. The objective of this study was to evaluate the effects of intravenous N-acetylcysteine on clinical and biochemical outcomes after coronary artery bypass surgery with cardiopulmonary bypass. One hundred patients (mean age 60.5 years, range 43-78 years, 89% male) undergoing coronary artery bypass grafting at the Montreal Heart Institute were randomized to receive either N-acetylcysteine (600 mg orally the day before and the morning of the operation, a bolus of 150 mg/kg of intravenous N-acetylcysteine before skin incision, followed by perfusion at 12.5 mg x kg(-1) x h(-1) over 24 hours; n = 50) or placebo (n = 50). The patients and clinical team were blinded to group assignments. Preoperative characteristics were similar between the two groups. Postoperative clinical data (death, myocardial infarction, low-output syndromes, arrhythmias, bleeding, transfusion requirements, and intensive care unit and hospital lengths of stay) and biochemical markers (creatine kinase MB, troponin T, creatinine, hemoglobin, and platelet levels) were evaluated serially over 4 days. Clinical outcomes were not significantly different between the two groups with regard to the incidence of death, myocardial infarction, bleeding, transfusion requirements, intubation time, and hospital length of stay. No differences were found in postoperative biochemical markers (troponin T, creatine kinase MB, creatinine, hemoglobin, and platelets) between the groups. No differences were observed between the groups in interleukin-6 production (P = not significant). Prophylactic use of N-acetylcysteine in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass does not lead to improvement in clinical results or biochemical markers. Further strategies to decrease reperfusion injury should be devised.

Short-term prognosis of patients with acute coronary syndromes through the evaluation of physical activity status, the adoption of Mediterranean diet and smoking habits: the Greek Acute Coronary Syndromes (GREECS) study

Our aim was to evaluate whether healthy dietary habits, physical activity and non-smoking are associated with less severe acute coronary syndromes and better short-term prognosis. From October 2003 to September 2004, 2172 patients (1649 males), hospitalized for severe acute coronary syndromes in six major hospitals in Greece were included in the study. The severity of severe acute coronary syndromes was assessed through troponin-I and maximum creatinine kinase MB levels, while 30-day recurrent event rate (death or rehospitalization for cardiovascular disease, angioplasty or coronary artery bypass surgery) was used to evaluate the prognosis of the patients. A 'healthy index' that assessed adherence to the Mediterranean diet, moderate alcohol intake, physical activity and abstinence from smoking was developed (range 0-4). One unit increment in the healthy index was associated with -12.4+/-2.4 ng/ml decrease in troponin I levels (P=0.001) and -9.7+/-2.5 ng/ml decrease in maximum creatinine kinase MB levels (P=0.001). The in-hospital mortality rate was 3.2% in males and 5.7% in females (i.e. overall 82 deaths, P=0.009); during the first 30 days following hospitalization the event rate was 15.7% in males and 16.3% in females (P=0.001). Values of the healthy index above one (i.e. presence of two or more protective factors) seemed to be associated with 44-84% lower risk of having recurrent events (P<0.001), even after various adjustments were made. Among patients who had had severe acute coronary syndromes, a healthy lifestyle seemed to be associated with less severe cardiac events and lower risk of death or rehospitalization 30 days after the event.

An AVS HDTV video decoder architecture employing efficient HW/SW partitioning

In this paper, we propose an optimized real-time AVS (a Chinese next-generation audio/video coding standard) HDTV video decoder. The decoder has been implemented in a single SoC with HW/SW partitioning. AVS algorithms and complexity are first analyzed. Based on the analysis, a hardware implementation of the MB level 7-stage pipeline is selected. The software tasks are realized with a 32-bit RISC processor. We further propose the optimization of interface and RISC processor based on the proposed architecture. The AVS decoder (RISC processor and hardware accelerators) is described in high-level Verilog/VHDL hardware description language and implemented in a single-chip AVS HDTV real-time decoder. At 148.5 MHz working frequency, the decoder chip can support real-time decoding of NTSC, PAL or HDTV (720p@60 frames/s or 1080i@60 fields/s) bit-streams. Finally, the decoder has been fully tested on a prototyping board

Clinical importance of elevated CK-MB and troponin I levels in congestive heart failure

Myocyte necrosis has been considered to play a fundamental role in the pathophysiology of congestive heart failure (CHF), which has usually evolved as a consequence of depletion of compensatory mechanisms and contractile reserve of myocardium. Elevated levels of creatine kinase MB (CK-MB) and troponin I (Tn-I) have been regarded as biochemical markers of myocyte necrosis. This study was planned to investigate the specificity and sensitivity of Tn-I and CK-MB in CHF and to examine the correlation of these markers with disease severity. A total of 104 patients (38 female, 66 male; mean age, 66 y [range, 36-89]) with symptoms and signs of heart failure on admission and with a reduced left ventricular ejection fraction (EF; by transthoracic echocardiography) were labeled "the patient group," and 58 patients (40 female,18 male; mean age, 61 y [range, 34-77]) with no signs or symptoms of CHF and with a normal EF detected by transthoracic echocardiography were included in the study as "the control group." Left ventricular EFs, end-diastolic diameters, and end-systolic diameters of patients in both groups were measured. Blood samples were drawn from all patients in both groups on admission, so that levels of CK-MB and Tn-I could be measured. All patients in both groups also underwent coronary angiography. Conditions leading to elevation of CK-MB or Tn-I were considered exclusion criteria. The 2 groups failed to show any significant differences in terms of mean age and the presence of coronary artery disease, hypertension, or diabetes mellitus (P>.05). Mean EF in the patient group was lower than that in the control group (P<.05). Mean CK-MB and Tn-I in the patient group were significantly higher than in the control group (P<.05). In the patient group, hypertensive patients were found to have significantly higher mean values of CK-MB than were seen in normotensive patients in the same group (P<.05). In the patient group, 52 cases were considered to be class I-II (New York Heart Association [NYHA]) (group 1), and 52 were considered to be class III-IV (group 2). Group 1, group 2, and the control group did not differ significantly from one another with regard to the presence of coronary artery disease, hypertension, and diabetes mellitus (P>.05). The mean EF in group 2 was significantly lower than that in group 1 and in the control group (P<.05); the mean EF in group 1 was significantly lower than that in the control group (P<.05). Group 1 values did not differ significantly from those of group 2 or the control group in terms of enzymatic markers (P>.05), but group 2 had significantly higher mean values of CK-MB and Tn-I than were noted in the control group (P<.05). The uphill course of CK-MB and Tn-I values from the control group to group 2 (NYHA class III-IV) was statistically significant (P<.05). Serum concentrations of CK-MB and Tn-I may become elevated in severely symptomatic patients with CHF (particularly NYHA class III-IV), demonstrating a relationship between clinical severity of the disease and elevation of myocardial enzymes (CK-MB and Tn-I).

The UW solution has greater potential for longer preservation periods than the Celsior solution: comparative study for ventricular and coronary endothelial function after 24-h heart preservation

Improvement of long-term heart preservation methods would potentially increase the donor pool and improve survival. We compared the efficacies of the University of Wisconsin (UW) and Celsior solutions on ventricular and endothelial functions after 24-h preservation. We used an isolated heart preparation perfused with blood. The heart was excised from a rabbit, stored for 24 h in the UW or Celsior solution, and then perfused with blood from a support-rabbit. We evaluated cardiac output and coronary endothelial function. The Frank-Starling curve showed a significant left and upward shift in the UW group compared with that in the Celsior group (p<0.01). There were no significant differences between the groups for the coronary blood flow in response to sodium nitroprusside or acetylcholine. The serum creatine kinase MB level after reperfusion was significantly lower in the UW group than in the Celsior group (10.7+/-1.4 ng/mL vs 30.4+/-5.4 ng/mL, p<0.01), whereas lipid peroxide levels did not differ significantly between the two groups. The UW group showed better left ventricular function than the Celsior group, indicating that the UW solution has greater potential for long-term preservation than Celsior solution.

Metabolic indicators in the skeletal muscles of harbor seals (Phoca vitulina)

The goal of this study was to determine the distribution of citrate synthase (CS), beta-hydroxyacyl coenzyme A dehydrogenase (HOAD), and lactate dehydrogenase (LDH) activities and myoglobin (Mb) concentration in the locomotor muscles (epaxial muscles) and heart of harbor seals. The entire epaxial musculature, which produces most of the power for submerged swimming, was removed and weighed, and three transverse sections (cranial, middle, and caudal) were taken along the muscle bundle. Multiple samples were taken along points on a circular grid using a 6-mm biopsy. A single sample was taken from the left ventricle of the heart. Muscle groups of similar function were taken from three dogs as a control. Mean values were calculated for four roughly equal quadrants in each transverse section of the epaxial muscles. There were no significant differences among the quadrants within any of the transverse sections for the three enzymes or Mb. However, there were significant differences in the mean enzyme activities and Mb concentrations along the length of the muscle. The middle and caudal sections had significantly higher mean levels of CS, LDH, and Mb than the cranial section, which may be correlated with power production during swimming. The enzyme ratios CS/HOAD and LDH/CS exhibited no variation within transverse sections or along the length of the epaxial muscles. Relative to the dog, the epaxial muscles and heart of the harbor seal had higher HOAD levels and lower CS/HOAD, which, taken together, indicate an increased capacity for aerobic lipid metabolism during diving.

Plasma Thioredoxin Level and Its Correlation to Myocardial Damage in Patients with Acute Myocardial Infarction who Underwent Successful Primary Angioplasty

Backgroud and Objectives:Oxidative stress is thought to play important role in cardiovascular disease. Thiore- doxin is an important biomarker for determining the degree of oxidative stress. However, the relationship between the plasma thioredoxin levels and myocardial damage has not been investigated. Subjects and Methods:We measured the plasma thioredoxin levels in the patients suffering with acute myocardial infarction and who also underwent successful primary angioplasty. We then compared the plasma thioredoxin levels and the clinical parameters in acute myocardial infarction patients (n=37) in order to examine the relationship between oxida- tive stress and myocardial damage. Results:The plasma thioredoxin level was significantly related with the initial WBC count (r=0.349, p<0.05) and the myocardial damage, the peak CK level (r=0.489, p<0.01), the CK in- crement (r=0.452, p<0.05), the peak MB level (r=0.417, p<0.05), and the MB increment (r=0.364, p<0.05). We divided the patients into two groups according to the plasma thioredoxin levels. There was a significant diffe- rence in myocardial damage between the low and high plasma thoiredoxin levels at the initial WBC count (10174.2±3380.4/uL vs 13500±3740.7/uL, respectively; p<0.01) and the cardiac enzyme, the peak CK level (2565.2±1389.9 IU/L vs 4045.9±1978.9 IU/L, respectively; p=0.02), the CK increment (2309.6±1351.8 IU/L vs 3762.8±2079.7 IU/L, respectively; p=0.03), the peak MB level (208.7±127.5 IU/L vs 322.7±146.3 IU/L, respectively; p=0.02), and the MB increment (173.8±128.4 IU/L vs 277.7±158.9 IU/L, respectively; p=0.05). Conclusion:High thioredoxin levels were associated with the degree of oxidative stress and the extent of myocardial damage. Thioredoxin levels may be used as a new surrogate biomarker for the severity of oxidative stress and the extent of myocardial damage in the patients suffering with acute myocardial infarction. (Korean Circulation J 2006;36:39-45)

Validation of a test model of induced dysmenorrhea

The myometrial hyperactivity and reduced uterine blood flow of primary dysmenorrhea is to a large extent caused by increased vasopressin secretion. A new therapeutic approach for this condition is to develop antagonists of uterine vasopressin V1a receptors. We studied a test model of vasopressin-induced dysmenorrhea in healthy, sterilized women and compared responses against those in dysmenorrheic subjects. Eight women with primary dysmenorrhea and eight sterilized, healthy women participated in recordings of intrauterine pressure and experienced pain on days 1-2 of two menstruations. We tried to identify biochemical markers in plasma of uterine ischemia. Furthermore, the effects of repeated bolus injections of 10 pmol/kg b w of vasopressin or placebo on these parameters were assessed. The vasopressin injections caused statistically significant increases in the area under the intrauterine pressure curve (AUC) in both healthy volunteers and patients with dysmenorrhea, the overall responses being greater in healthy volunteers. The experienced pain measured by visual analog scale in individual dysmenorrheic subjects tended to show higher maximal post-dose scores for the vasopressin injections than for placebo. Maximum visual analog scale scores and maximum AUCs in individual subjects tended to be related. Mean creatine kinase MB levels were higher in women with dysmenorrhea than in healthy subjects both before and after vasopressin administration, the converse being observed for C-reactive protein levels. The present model appears to be useful for evaluating new drugs for the treatment of primary dysmenorrhea.

Effect of N-acetylcysteine on oxidative stress and ventricular function in patients with myocardial infarction

Recent evidence suggests that postischemic myocardial dysfunction ("stunning") may be mediated by oxygen free radicals. Various studies have reported the beneficial effects of antioxidants in ischemia-reperfusion injury. The aim of this study was to assess the effect of N-acetylcysteine (NAC) treatment on oxidative stress, infarct size, and left ventricular (LV) function, as adjunct therapy in myocardial infarction (MI). Patients with acute MI received either 15 g NAC infused over 24 h (n = 15) or no NAC (n = 15), combined with streptokinase. Peripheral venous blood was serially sampled to measure creatine kinase (CK)-MB levels. Plasma malondialdehyde (MDA) level was measured at admission and after 4 and 24 h. Echocardiography was performed within 3 days of MI and after 3 months. At admission, plasma MDA levels were not different between the groups. In the NAC-treated patients plasma MDA levels decreased, whereas in the nontreated NAC patients MDA levels increased at 4 and 24 h (P < 0.01 and P < 0.001, respectively). Left ventricular ejection fraction was higher (P < 0.05) and LV end-systolic and end-diastolic diameters were lower (P < 0.001 and P < 0.001) in patients receiving NAC on day 3. Left ventricular wall motion score index was significantly lower in patients treated with NAC on day 3 (P < 0.05). Left ventricular diastolic parameters were not different whether patients were treated with NAC or not. No difference in reduction of infarct size was detected between the groups according to CK-MB levels. It was thus demonstrated that administration of NAC in combination with streptokinase significantly diminished oxidative stress and improved LV function in patients with acute MI. These encouraging results would justify the performance of a larger controlled study.

Bivalirudin compared with IIb/IIIa inhibitors in patients with in-stent restenosis undergoing intracoronary brachytherapy

Bivalirudin is replacing heparin in percutaneous coronary interventions (PCIs), including vascular brachytherapy (VBT). The aim of the study was to compare bivalirudin with eptifibatide in patients with in-stent restenosis (ISR) undergoing PCI and VBT. One hundred forty-four patients treated with bivalirudin as a single antithrombotic agent were compared with 150 patients treated with eptifibatide. Bivalirudin as a bolus of 0.75 mg/kg followed by 1.75 mg/kg/h infusion until the end of the procedure, and eptifibatide as a double bolus of 180 microg/kg followed by 2 microg/kg/min infusion for 18 h after the procedure were used. The main outcome measures were in-hospital events and 30-day clinical outcomes. Baseline clinical characteristics were similar except that patients in the eptifibatide group were younger (P=.02) and had more saphenous vein graft lesions (P<.001). Patients in the bivalirudin group had a higher number of lesions in the right coronary artery (P<.001) and a higher number of vessels treated (P<.001). Postprocedure creatinine phosphokinase (CPK)-MB levels were significantly lower in the bivalirudin group (P<.03). In-hospital events showed significantly less minor bleeding (P=.01) and a trend toward lower major bleeding and major adverse cardiac events (MACE) in the bivalirudin group (P=.06). Thirty-day outcomes showed a significantly lower incidence of non-Q-wave myocardial infarction (MI) in the bivalirudin group (P=.004). Bivalirudin, as a single antithrombotic agent during PCI and VBT, is associated with significantly lower postprocedural CPK-MB elevation, minor bleeding complications, 30-day non-Q-wave MI rates, and a trend toward lower major bleeding and in-hospital MACE when compared with eptifibatide.

POSTOPERATIVE CREATINE KINASE MB LEVEL IS ASSOCIATED WITH IN-HOSPITAL MORTALITY AFTER CORONARY SURGERY

PURPOSE: Cardiac enzymes are widely used for evaluation of perioperative myocardial injury. This study was to investigate the potential relationship between postoperative creatine kinase MB (CKMB) level and clinical outcomes in the patients after isolated coronary artery bypass grafting (CABG).

Ginsenosides compound (shen-fu) attenuates gastrointestinal injury and inhibits inflammatory response after cardiopulmonary bypass in patients with congenital heart disease

This study was undertaken to demonstrate that gastrointestinal mucosal injury occurs during cardiopulmonary bypass in children, increasing systemic inflammatory responses, and to determine whether shen-fu injection (the major components of which are ginsenosides compound, extract of Panax ginseng shown to have antioxidant properties) could attenuate gastrointestinal mucosal injury and subsequent inflammatory responses. Twenty-four children undergoing heart surgery for congenital heart defects were randomly assigned to groups C (placebo control, n = 12) and G (1.35 mg/kg ginsenosides compound intravenously before and throughout the course of cardiopulmonary bypass, n = 12). Central venous blood samples were taken before cardiopulmonary bypass and at 60 and 120 minutes after aortic declamping (reperfusion). Gastric intramucosal pH was measured by perioperative tonometry. Plasma lipid peroxidation product malondialdehyde, myocardium-specific creatine kinase isoenzyme MB activity, diamine oxidase, lipopolysaccharide, and interleukin 6 were all measured. Significant decrease in gastric intramucosal pH and increase in plasma diamine oxidase were seen during reperfusion in group C, accompanied by increases in plasma levels of malondialdehyde, lipopolysaccharide, interleukin 6, and creatine kinase isoenzyme MB (P < .01 vs before cardiopulmonary bypass). Shen-fu injection significantly attenuated these changes (P < .05). Consequently, fewer patients in group G (2/12) than in group C (7/12) needed postoperative inotropic support. Postoperative intensive care unit stay was shorter in group G than in group C. A tight positive correlation was seen between diamine oxidase and interleukin 6 at 60 minutes after aortic declamping and between diamine oxidase and lipopolysaccharide at 120 minutes after aortic declamping (r = 0.79, P < .0001). Ginsenosides compound may attenuate gastrointestinal injury and inhibit inflammatory response after cardiopulmonary bypass in patients with congenital heart disease.

Relaxation dynamics of simple glass‐formers: The role of timescale separation and activated dynamics at the metabasin level

Within the landscape approach the dynamical heterogeneities presented by model glasses at low temperatures have been shown to represent well-defined elemental activated events in the exploration of the potential energy surface, PES. This last picture relies on the validity of a timescale separation hypothesis: Transitions within basins of attraction or Inherent Structures, ISs, of the PES must be fast compared to transitions between ISs. Additionally, ISs might be grouped in metabasins, MBs, the transition between them involving infrequent large scale rearrangements. In this work we clearly demonstrate the MB superstructure of the PES and study the T dependence of the MB dynamics. We find that beyond certain T timescale separation begins to break down both at the IS and the MB levels, which implies the cessation of the prevalence of activated dynamics as the system loses complexity, diversity and glassiness. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Can creatine kinase MB levels predict mortality after cardiac surgery?

Can creatine kinase MB levels predict mortality after cardiac surgery?

Randomized Trial of High Loading Dose of Clopidogrel for Reduction of Periprocedural Myocardial Infarction in Patients Undergoing Coronary Intervention

Aggressive platelet inhibition is crucial to reduce myocardial injury and early cardiac events after coronary intervention. Although observational data have suggested that pretreatment with a high loading dose of clopidogrel may be more effective than a conventional dose, this hypothesis has never been tested in a randomized trial. A total of 255 patients scheduled to undergo percutaneous coronary intervention were randomized to a 600-mg (n=126) or 300-mg (n=129) loading regimen of clopidogrel given 4 to 8 hours before the procedure. Creatine kinase MB, troponin I, and myoglobin levels were measured at baseline and at 8 and 24 hours after intervention. The primary end point was the 30-day occurrence of death, myocardial infarction (MI), or target vessel revascularization. The primary end point occurred in 4% of patients in the high loading dose versus 12% of those in the conventional loading dose group (P=0.041) and was due entirely to periprocedural MI. Peak values of all markers were significantly lower in patients treated with the 600-mg regimen (P< or =0.038). Safety end points were similar in the 2 arms. At multivariable analysis, the high loading regimen was associated with a 50% risk reduction of MI (OR 0.48, 95% CI 0.15 to 0.97, P=0.044). An incremental benefit was observed in patients randomized to the 600-mg dose who were receiving statins, with an 80% risk reduction. Pretreatment with a 600-mg loading dose of clopidogrel 4 to 8 hours before the procedure is safe and, as compared with the conventional 300-mg dose, significantly reduced periprocedural MI in patients undergoing percutaneous coronary intervention. These results may influence practice patterns with regard to antiplatelet therapy before percutaneous revascularization.

Rate Control for Real-Time Video Network Transmission on End-To-End Rate-Distortion and Application-Oriented QoS

In the merged multimedia packet-switched networks, the limited or no end-to-end Quality of Service (QoS) guarantees induce that rate control has been evolved to joint source-channel adjustment architecture based on application-oriented QoS. Based on the statistical analysis under the spatial intra and temporal inter prediction subject to a universal spatial-temporal coding framework and a general error concealment by the decoder, an end-to-end distortion estimation model is proposed. On the basis of the analytic model, this paper fulfills a picture quality parameters selection solution with rate-distortion (R-D) Lagrange optimization for a general coding engine including H.264/AVC, exploiting either the source-driven iterative prediction or feedback recursion. Further, a corresponding joint source-channel rate control strategy is proposed. For the real-time variable bit-rate (VBR) video transmission under a given time-varying network condition, the strategy could estimate an instantaneous available transmission rate on traffic smoothing and codec's buffer control, adopt the proposed an end-to-end distortion regressive model and a global optimal error control parameters selection, and address the consistent bit allocation in group of picture (GOP) level, picture level, and MB level. The extensive network simulation experiments show a better and more consistent end-to-end picture quality, in contrast with the locally optimal control strategy at MB level.

Increased creatine kinase MB level predicts postoperative mortality after cardiac surgery independent of new Q waves

Recent consensus statements recommend cardiac enzyme release as the essential criterion for diagnosing myocardial infarction. However, the outcome implications of cardiac enzyme release in patients undergoing coronary artery bypass grafting are controversial. Eight hundred patients were followed for 30 days after elective on-pump coronary artery bypass grafting in a multicenter, prospective, randomized trial of the anti-C5 complement antibody pexelizumab. Data from centralized electrocardiography and creatine kinase MB analyses were examined for any association with death or severe left ventricular dysfunction. More than half of the 800 patients had peak creatine kinase MB levels of more than 5 times the upper limit of 5 ng/mL set by the core laboratory. The median peak value was 29 ng/mL. The incidence of the combined outcome (death or severe left ventricular dysfunction) was 1.7% if the peak creatine kinase MB level was less than 25 ng/mL and 18.0% if 100 ng/mL or greater (P < .01). Similarly, the incidence of new Q-wave myocardial infarction was 3.9% if the peak creatine kinase MB level was less than 25 ng/mL and 30.6% if 100 ng/mL or greater (P < .01). In a multivariate analysis that included preoperative and intraoperative factors, as well as peak enzyme release and Q-wave myocardial infarction, the strongest predictor of the combined outcome was a peak creatine kinase MB level of 100 ng/mL or greater. New Q-wave myocardial infarction did not significantly predict the combined outcome. Increased postoperative peak creatine kinase MB level, especially when 20 times or more of the upper limit of normal, indicates increased risk of severe postoperative left ventricular dysfunction and mortality within 30 days of coronary artery bypass grafting. High peak enzyme level is a stronger predictor of adverse outcomes than is postoperative Q-wave myocardial infarction in this population.