Hyperglycemia exaggerates ischemia-reperfusion-induced cardiomyocyte injury: reversal with endothelin antagonism

Perioperative Glycemic Management in Cardiac Surgery: A Narrative Review

Diabetes and hyperglycemic events in cardiac surgical patients are associated with postoperative morbidity and mortality. The causes of dysglycemia, the abnormal fluctuations in blood glucose concentrations, in the perioperative period include surgical stress, surgical techniques, medications administered perioperatively, and patient factors. Both hyperglycemia and hypoglycemia lead to poor outcomes after cardiac surgery. While trying to control blood glucose concentration tightly for better postoperative outcomes, hypoglycemia is the main adverse event. Currently, there is no definite consensus on the optimum perioperative blood glucose concentration to be maintained in cardiac surgical patients. This review provides an overview of perioperative glucose homeostasis, the pathophysiology of dysglycemia, factors that affect glycemic control in cardiac surgery, and current practices for glycemic control in cardiac surgery.

High Glucose Activates Prolyl Hydroxylases and Disrupts HIF-α Signaling via the P53/TIGAR Pathway in Cardiomyocyte

The induction of hypoxia tolerance has emerged as a novel therapeutic strategy for the treatment of ischemic diseases. The disruption of hypoxic signaling by hyperglycemia has been shown to contribute to diabetic cardiomyopathy. In this study, we explored the potential molecular mechanisms by which high glucose (HG) impairs hypoxia-inducible factor-α (HIF-α) signaling in cardiomyocytes. The exposure of H9c2 cell lines to HG resulted in time- and concentration-dependent decreases in HIF-1α and HIF-2α expression together with an increase in prolyl hydroxylase-1,2 (PHD1 and PHD2) expression, the main regulators of HIF-α destabilization in the heart. The exposure of H9c2 cells to normal glucose (5.5 mM) and high glucose (15, 30, and 45 mM) led to dose-dependent increases in p53 and TIGAR and a decrease in SIRT3 expression. The pretreatment of H9c2 with p53 siRNA to knockdown p53 attenuated PHD1 and PHD2 expression, thus significantly enhancing HIF-1α and HIF-2α expression in H9c2 cells under HG conditions. Interestingly, pretreatment with p53 siRNA altered H9c2 cell metabolism by reducing oxygen consumption rate and increasing glycolysis. Similarly, pretreatment with TIGAR siRNA blunted HG-induced PHD1 and PHD2 expression. This was accompanied by an increase in HIF-1α and HIF-2α expression with a reduction in oxygen consumption rate in H9c2 cells. Furthermore, pretreatment with adenovirus-SIRT3 (Ad-SIRT3) significantly reduced the HG-induced expression of p53 and PHDs and increased HIF-1α levels in H9c2 cells. Ad-SIRT3 treatment also regulated PHDs-HIF-1α levels in the hearts of diabetic db/db mice. Our study revealed a novel role of the HG-induced disruption of PHDs-HIF-α signaling via upregulating p53 and TIGAR expression. Therefore, the p53/TIGAR signaling pathway may be a novel target for diabetic cardiomyopathy.

High Glucose-Induced Cardiomyocyte Damage Involves Interplay between Endothelin ET-1/ETA/ETB Receptor and mTOR Pathway

Patients with type two diabetes mellitus (T2DM) are at increased risk for cardiovascular diseases. Impairments of endothelin-1 (ET-1) signaling and mTOR pathway have been implicated in diabetic cardiomyopathies. However, the molecular interplay between the ET-1 and mTOR pathway under high glucose (HG) conditions in H9c2 cardiomyoblasts has not been investigated. We employed MTT assay, qPCR, western blotting, fluorescence assays, and confocal microscopy to assess the oxidative stress and mitochondrial damage under hyperglycemic conditions in H9c2 cells. Our results showed that HG-induced cellular stress leads to a significant decline in cell survival and an impairment in the activation of ETA-R/ETB-R and the mTOR main components, Raptor and Rictor. These changes induced by HG were accompanied by a reactive oxygen species (ROS) level increase and mitochondrial membrane potential (MMP) loss. In addition, the fragmentation of mitochondria and a decrease in mitochondrial size were observed. However, the inhibition of either ETA-R alone by ambrisentan or ETA-R/ETB-R by bosentan or the partial blockage of the mTOR function by silencing Raptor or Rictor counteracted those adverse effects on the cellular function. Altogether, our findings prove that ET-1 signaling under HG conditions leads to a significant mitochondrial dysfunction involving contributions from the mTOR pathway.

Effects of SGLT2 Inhibitors on Kidney and Cardiovascular Function

SGLT2 inhibitors are antihyperglycemic drugs that protect kidneys and the heart of patients with or without type 2 diabetes and preserved or reduced kidney function from failing. The involved protective mechanisms include blood glucose-dependent and -independent mechanisms: SGLT2 inhibitors prevent both hyper- and hypoglycemia, with expectedly little net effect on HbA1C. Metabolic adaptations to induced urinary glucose loss include reduced fat mass and more ketone bodies as additional fuel. SGLT2 inhibitors lower glomerular capillary hypertension and hyperfiltration, thereby reducing the physical stress on the filtration barrier, albuminuria, and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular gluco-toxicity, may preserve tubular function and glomerular filtration rate in the long term. SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves organ oxygen delivery. SGLT2 inhibitors are proximal tubule and osmotic diuretics that reduce volume retention and blood pressure and preserve heart function, potentially in part by overcoming the resistance to diuretics and atrial-natriuretic-peptide and inhibiting Na-H exchangers and sympathetic tone.

Stress hyperglycemia, cardiac glucotoxicity, and critically ill patient outcomes current clinical and pathophysiological evidence

Stress hyperglycemia is a transient increase in blood glucose during acute physiological stress in the absence of glucose homeostasis dysfunction. Its's presence has been described in critically ill patients who are subject to many physiological insults. In this regard, hyperglycemia and impaired glucose tolerance are also frequent in patients who are admitted to the intensive care unit for heart failure and cardiogenic shock. The hyperglycemia observed at the beginning of these cardiac disorders appears to be related to a variety of stress mechanisms. The release of major stress and steroid hormones, catecholamine overload, and glucagon all participate in generating a state of insulin resistance with increased hepatic glucose output and glycogen breakdown. In fact, the observed pathophysiological response, which appears to regulate a stress situation, is harmful because it induces mitochondrial impairment, oxidative stress-related injury to cells, endothelial damage, and dysfunction of several cellular channels. Paradigms are now being challenged by growing evidence of a phenomenon called glucotoxicity, providing an explanation for the benefits of lowering glucose levels with insulin therapy in these patients. In the present review, the authors present the data published on cardiac glucotoxicity and discuss the benefits of lowering plasma glucose to improve heart function and to positively affect the course of critical illness.

Recipient hypertonic saline infusion prevents cardiac allograft dysfunction

OBJECTIVE

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

METHODS

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

RESULTS

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

CONCLUSIONS

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.

Incidence, mechanisms and impact outcome of hyperglycaemia in severe scorpion-envenomed patients

Hyperglycaemia is often observed in severe scorpion-envenomed patients. It is due to a severe autonomic storm with a massive release of catecholamines, increased glucagon levels, cortisol levels, and either decreased insulin levels or insulin resistance. The presence of hyperglycaemia is an indicator of severity in this specific condition. Indeed, hyperglycaemia was associated with the severity of clinical manifestations of severe scorpion envenomation requiring intensive care unit (ICU) admission. In fact, the presence of hyperglycaemia was associated with the presence of respiratory failure, pulmonary oedema, haemodynamic instability, neurological failure, multisystem organ failure, and an increased mortality and ICU length of stay. As a consequence, we think the presence of hyperglycaemia in scorpion-envenomed patients at the emergency department prompts searching for presence of systemic manifestations or cardiorespiratory manifestations. As a consequence, the presence of hyperglycaemia can help screen severe patients at the emergency department. The current management of severe scorpion envenomation involves the admission and close surveillance in the ICU, where vital signs and continuous monitoring enable early initiation of therapy for life-threatening complications. The use of antivenom for scorpion stings remains controversial. All patients with pulmonary oedema should receive prazosin and possibly dobutamine, according the scorpion's species. Mechanical ventilation is usually used in severe cases. Insulin should be reserved for severe cases with confirmed excessive hyperglycaemia (>10 mmol/l).

Effects of Ischemic and Proton Pump Inhibitors Preconditioning on Oxidative Stress of Isolated Rat Heart

Aim of present study was to determine the participation of various biomarkers of oxidative damage: nitrite (NO2 −), superoxide anion radicals (O2 −), index of lipid peroxidation (TBARS) and hydrogen peroxide (H2O2) in coronary circulation after application of the different models of preconditioning such as ischemic and preconditioning with proton pump inhibitors.

Examining a biochemical markers of oxidative damage we did not notice any increased production values of any parameter, according to that we can hypothesize that possible occurrence of reperfusion injury after ischemia and PPIs preconditioning is not mediated by this mechanism.

Due to the very difficult and controversial application of ischemic preconditioning in clinical practice, the results of this study suggest that in the future proton pump inhibitors can contribute to the prevention of myocardial damage following ischemia

Blockade of Endothelin-1 Receptor Type B Ameliorates Glucose Intolerance and Insulin Resistance in a Mouse Model of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is associated with insulin resistance (IR) and glucose intolerance. Elevated endothelin-1 (ET-1) levels have been observed in OSA patients and in mice exposed to intermittent hypoxia (IH). We examined whether pharmacological blockade of type A and type B ET-1 receptors (ETA and ETB) would ameliorate glucose intolerance and IR in mice exposed to IH. Subcutaneously implanted pumps delivered BQ-123 (ETA antagonist; 200 nmol/kg/day), BQ-788 (ETB antagonist; 200 nmol/kg/day) or vehicle (saline or propyleneglycol [PG]) for 14 days in C57BL6/J mice (10/group). During treatment, mice were exposed to IH (decreasing the FiO2 from 20.9% to 6%, 60/h) or intermittent air (IA). After IH or IA exposure, insulin (0.5 IU/kg) or glucose (1 mg/kg) was injected intraperitoneally and plasma glucose determined after injection and area under glucose curve (AUC) was calculated. Fourteen-day IH increased fasting glucose levels (122 ± 7 vs. 157 ± 8 mg/dL, PG: 118 ± 6 vs. 139 ± 8; both p < 0.05) and impaired glucose tolerance (AUCglucose: 19,249 ± 1105 vs. 29,124 ± 1444, PG AUCglucose: 18,066 ± 947 vs. 25,135 ± 797; both p < 0.05) in vehicle-treated animals. IH-induced impairments in glucose tolerance were partially ameliorated with BQ-788 treatment (AUCglucose: 21,969 ± 662; p < 0.05). Fourteen-day IH also induced IR (AUCglucose: 7185 ± 401 vs. 8699 ± 401; p < 0.05). Treatment with BQ-788 decreased IR under IA (AUCglucose: 5281 ± 401, p < 0.05) and reduced worsening of IR with IH (AUCglucose: 7302 ± 401, p < 0.05). There was no effect of BQ-123 on IH-induced impairments in glucose tolerance or IR. Our results suggest that ET-1 plays a role in IH-induced impairments in glucose homeostasis.

Admission Glucose and In-hospital Mortality after Acute Myocardial Infarction in Patients with or without Diabetes: A Cross-sectional Study

Background:

Hyperglycemia on admission has been found to elevate risk for mortality and adverse clinical events after acute myocardial infarction (AMI), but there are evidences that the relationship of blood glucose and mortality may differ between diabetic and nondiabetic patients. Prior studies in China have provided mixed results and are limited by statistical power. Here, we used data from a large, nationally representative sample of patients hospitalized with AMI in China in 2001, 2006, and 2011 to assess if admission glucose is of prognostic value in China and if this relationship differs depending on the presence or absence of diabetes.

Methods:

Using a nationally representative sample of patients with AMI in China in 2001, 2006, and 2011, we categorized patients according to their glucose levels at admission (< 3.9, 3.9–7.7, 7.8–11.0, and ≥11.1 mmol/L) and compared in-hospital mortality across these admission glucose categories, stratified by diabetes status. Among diabetic and nondiabetic patients, separately, we employed logistic regression to assess the differences in outcomes across admission glucose levels while adjusting for the same covariates.

Results:

Compared to patients with euglycemia (5.8%), patients with moderate hyperglycemia (13.1%, odds ratio [OR] = 2.44, 95% confidence interval [CI, 2.08–2.86]), severe hyperglycemia (21.5%, OR = 4.42, 95% CI [3.78–5.18]), and hypoglycemia (13.8%, OR = 2.59, 95% CI [1.68–4.00]), all had higher crude in-hospital mortality after AMI regardless of the presence of recognized diabetes mellitus. After adjustment for patients’ characteristics and clinical status, however, the relationship between admission glucose and in-hospital mortality was different for diabetic and nondiabetic patients (P for interaction = 0.045). Among diabetic patients, hypoglycemia (OR = 3.02, 95% CI [1.20–7.63]), moderate hyperglycemia (OR = 1.75, 95% CI [1.04–2.92]), and severe hyperglycemia (OR = 2.97, 95% CI [1.87–4.71]) remained associated with elevated risk for mortality, but among nondiabetic patients, only patients with moderate hyperglycemia (OR = 2.34, 95% CI [1.93–2.84]) and severe hyperglycemia (OR = 3.92, 95% CI [3.04–5.04]) were at elevated mortality risk and not hypoglycemia (OR = 1.12, 95% CI [0.60–2.08]). This relationship was consistent across different study years (P for interaction = 0.900).

Conclusions:

The relationship between admission glucose and in-hospital mortality differs for diabetic and nondiabetic patients. Hypoglycemia was a bad prognostic marker among diabetic patients alone. The study results could be used to guide risk assessment among AMI patients using admission glucose.

Trial Registration:

www.clinicaltrials.gov, NCT01624883; https://clinicaltrials.gov/ct2/show/NCT01624883

Non-diabetic clinical applications of insulin

BACKGROUND

Introducing a new drug to the market is a time-consuming process, is complex, and involves consumption of a lot of resources. Therefore, discovering new uses for the old drugs (i.e. drug repurposing) benefits the patients by providing them time-tested drugs. With developments in insulin therapy still happening, it is worth keeping up to date on trends in the use of this powerful glucose-lowering agent. The aim of this article is to explore the potential non-diabetic clinical applications of insulin.

METHODS

Literature survey was carried out through the various scientific journals publishing experimental and clinical research papers regarding the diverse applications of insulin other than in diabetes mellitus. These applications include both therapeutic as well as diagnostic uses of insulin. The relevant information collected from these publications was paraphrased in the present paper.

RESULTS

On studying the literature, the non-diabetic uses of insulin include the following: wound healing, parenteral nutrition, antiaging, body building, cardioprotection in acute coronary syndromes, insulin tolerance test to test the hypothalamo-pituitary-adrenal axis functioning, cell culture, cancer treatment, organ preservation, and management of septic shock, calcium channel, β-blocker overdose and other critical illnesses in intensive care units.

CONCLUSIONS

This review attempts to survey some interesting new applications of insulin other than in diabetes mellitus.

Admission hyperglycemia is associated with poor outcome after emergent coronary bypass grafting surgery

PURPOSE

Hyperglycemia during or after cardiac surgery is a common finding that is associated with poor outcome. Very few data, however, are available regarding a correlation between admission blood glucose and outcomes after coronary artery bypass grafting (CABG). Thus, the goal of the current study was to examine the relationship between admission blood glucose and outcome after emergency CABG surgery.

MATERIALS AND METHODS

A retrospective analysis to evaluate whether admission hyperglycemia associated with increased morbidity or mortality was performed in patients after emergency CABG surgery. The records of all the patients undergoing emergency CABG surgery between January 1999 and December 2010 at the University of Virginia Health System were reviewed. Postoperative in-hospital mortality and complications were considered as study end points.

RESULTS

A total of 240 patients met the final inclusion criteria. Overall mortality was 14.1%. The median admission blood glucose in patients who died 7.4 (interquartile range, 5.9-10.1) mmol/L was significantly higher compared with survivors 6.1 (interquartile range, 5.4-7.2; P<.01). Furthermore, 59% of the patients who died had admission blood glucose levels higher than 6.6 mmol/L, whereas only 35% of the patients who survived had similar blood glucose levels (P=.01). On multivariable analysis, admission blood glucose was identified as an independent risk factor for death after emergency CABG (P=.01; odds ratio, 1.16; 95% confidence interval, 1.04-1.29). Admission blood glucose was further identified as independently associated with increased risk for a composite outcome of death, postoperative renal failure or stroke (P=.01; odds ratio, 1.14; 95% confidence interval, 1.03-1.27).

CONCLUSIONS

Our study shows for the first time that admission blood glucose is correlated with increased morbidity and mortality among patients undergoing emergency CABG surgery.

Erythropoietin protects myocardium against ischemia-reperfusion injury under moderate hyperglycemia

Erythropoietin (EPO), an essential hormone for erythropoiesis, provides protection against myocardial ischemia/reperfusion (I/R) injury. Hyperglycemia during acute myocardial infarction aggravates organ damage and attenuates the efficacies of various protective measures. This study aimed to investigate the protective role of EPO against myocardial I/R injury under a clinically relevant moderate hyperglycemic condition and its associated mechanisms. Eighty-two Sprague-Dawley rats were randomly assigned to six groups: normoglycemia-Sham, normoglycemia-I/R-control-saline (IRC), normoglycemia-I/R-EPO (IRE), hyperglycemia-Sham, hyperglycemia-IRC, and hyperglycemia-IRE. The rats received 1.2 g/kg dextrose or same volume of normal saline depending on the group. I/R was induced by a 30 min period of ischemia followed by reperfusion for 4 h. For 1 h before I/R injury, intravenous 4000 IU/kg of EPO was administered. EPO pretreatment significantly reduced the number of apoptotic cells and the infarct size compared with those of the control groups. EPO increased GATA-4 phosphorylation and acetylation against I/R in hyperglycemic myocardium. It also enhanced ERK induced GATA-4 post-translational modifications such as increased GATA-4 phosphorylation and acetylation, and decreased GATA-4 ubiquitination following hypoxia-reoxygenation in H9c2 cells in hyperglycemic medium. Increased GATA-4 stability by EPO diminished I/R-related down-regulation of Bcl-2 and reduction of caspase-3 activities in hyperglycemic myocardium. In conclusion, EPO pretreatment before I/R injury conveyed significant myocardial protection under moderate hyperglycemic condition through mechanisms involved in reduction of caspase-3 activity and up-regulation of Bcl-2 in association with enhanced ERK-induced GATA-4 stability.

Mechanisms involved in attenuated cardio-protective role of ischemic preconditioning in metabolic disorders

Myocardial infarction is a pathological state which occurs due to severe abrogation of the blood supply (ischemia) to a part of heart, which can cause myocardial damage. The short intermittent cycles of sub-lethal ischemia and reperfusion has shown to improve the tolerance of the myocardium against subsequent prolonged ischemia/reperfusion (I/R)-induced injury, which is known as ischemic preconditioning (IPC). Although, IPC-induced cardioprotection is well demonstrated in various species, including human beings, accumulated evidence clearly suggests critical abrogation of the beneficial effects of IPC in diabetes mellitus, hyperlipidemia and hyperhomocysteinemia. Various factors are involved in the attenuation of the cardioprotective effect of preconditioning, such as the reduced release of calcitonin gene-related peptide (CGRP), the over-expression of glycogen synthase kinase-3β (GSK-3β) and phosphatase and tensin homolog (PTEN), impairment of mito-KATP channels, the consequent opening of mitochondrial permeability transition pore (MPTP), etc. In this review, we have critically discussed the various signaling pathways involved in abrogated preconditioning in chronic diabetes mellitus, hyperlipidemia and hyperhomocysteinemia. We have also focused on the involvement of PTEN in abrogated preconditioning and the significance of PTEN inhibitors.

Protective effects of tight glucose control during cardiopulmonary bypass on myocardium in adult nondiabetic patients undergoing valve replacement

BACKGROUND

In this study, we aimed to evaluate the protective effect of tight glucose control during cardiopulmonary bypass on myocardium in adult nondiabetic patients undergoing isolated aortic valve replacement in a prospective and randomized trial.

METHODS

Sixty-five adult nondiabetic patients undergoing selective isolated aortic valve replacement were enrolled and randomly assigned to an insulin group (patients received a continuous insulin infusion during surgery; n = 33) or a control group (patients were not administered insulin unless their blood glucose level exceeded 200 mg/dL; n = 32). Cardiac troponin I was assayed preoperatively, and then at 2, 6, 12, 24, and 48 hours after aortic cross-declamping. The pre-, intra-, and postoperative relevant data of all selected patients were analyzed.

RESULTS

Tight glucose control reduced postoperative peak release by 48% for cardiac troponin I compared with the control group (0.48 ± 0.12 vs 0.71 ± 0.17 ng/mL; P < 0.0001). Patients with continuous insulin infusion had lower peak inotropic score during the first postoperative 24 hours and peak level of blood glucose (5.8 ± 2.2 vs 8.2 ± 3.1 μg/kg/min; P < 0.0001; 131.9 ± 23.8 vs 191.1 ± 38.5 mg/dL; P < 0.001, respectively), shorter duration of mechanical ventilation and intensive care unit stay and hospital stay compared with the control group (11.6 ± 2.9 hours vs 14.8 ± 3.5 hours; P = 0.0002; 28.4 ± 7.2 hours vs 36.5 ± 7.8 hours; P < 0.0001; 9.4 ± 3.3 days vs 11.5 ± 4.2 days; P = 0.0283, respectively).

CONCLUSIONS

Tight glucose control during cardiopulmonary bypass might provide myocardial protection in adult nondiabetic patients undergoing isolated aortic valve replacement.

How important is glycemic control during coronary artery bypass?

In summary, poor perioperative glycemic control in patients undergoing CABG is associated with increased morbidity and mortality. Maintaining serum glucose less than or equal to 180 mg/dL in patients with diabetes during CABG reduces morbidity and mortality, lowers the incidence of wound infections, reduces hospital length of stay, and enhances long-term survival. In nondiabetic patients undergoing CABG surgery, maintaining serum glucose less than 180 mg/dL has also resulted in improved perioperative outcomes. More aggressive glycemic control (80-120 mg/dL) provides no added improvement in CABG patients with less than or equal to 3 days of ICU care in the absence of ventilatory support or multiorgan failure. Although the precise value for achieving glycemic control in the perioperative period is the subject of much debate, the benefits of perioperative glycemic control with continuous insulin infusions in patients undergoing CABG is no longer debatable.

Prognostic value of admission blood glucose concentration and diabetes diagnosis on survival after acute myocardial infarction: results from 4702 index cases in routine practice

The diagnosis of diabetes and admission blood glucose concentration are associated with adverse outcome after acute coronary syndromes. We compared the relative association with survival after ST elevation AMI (acute myocardial infarction) of admission blood glucose concentration and of diabetes diagnosis. We carried out a retrospective cohort study in 4702 consecutive patients with STEMI (ST elevation AMI) occurring from 1 April 1993 to 31 December 2005, assessed for mortality at 30 days and 1 year. Patients were classified according to antecedent diabetes and by blood glucose concentration at admission (quartile 1, <7 mmol/l; quartile 2, 7–8.2 mmol/l;quartile 3, 8.3–10.9 mmol/l; quartile 4, 11 mmol/l). Multivariable models were constructed for determinants of mortality, including year of STEMI and demographic variables, entering blood glucose concentration and antecedent diabetes individually and together. All-cause 30-day and 1-year mortality were 22.8% and 31.3% for patients with antecedent diabetes, compared with 16.3% and 23.0% respectively for those without. For glucose quartiles 1, 2, 3 and 4, crude 30-day mortality was 9.0%, 10.6%, 17.9% and 31.0%. Adjusted 30-day mortality risk was similar in quartile 2, higher by >80% in quartile 3 and by >150% in quartile 4, compared with glucose quartile 1. Antecedent diabetes was associated with an increase in mortality [unadjusted odds ratio (OR)1.52 (95% CI 1.24, 1.86)]. On multivariable analysis (excluding glucose quartile), this reduced to 1.24 (0.98, 1.58) and changed to a small, statistically non-significant reduction in risk when glucose quartile was added to the analysis [adjusted OR 0.87 (0.67, 1.13)]. Inclusion of antecedent diabetes in multivariable models did not add to the predictive value for mortality of glucose quartile(P=0.368). Similar relationships were observed for 1 year mortality. In patients with STEMI, blood glucose concentration shows graded association with risk of 30-day and 1-year mortality and is of greater prognostic relevance than antecedent diabetes diagnosis. Moderate elevation of blood glucose, below levels previously considered to be clinically relevant, is associated with adverse impact on survival.

Production of free radicals and oxygen consumption by primary equine endothelial cells during anoxia-reoxygenation

The endothelium plays an active role in ischemia/reperfusion injuries. Herein, we report the effect of a single or successive cycles of anoxia/reoxygenation (A/R) on the mitochondrial respiratory function of equine endothelial cells (cultured from carotids) monitored by high resolution oxymetry, and on their production of reactive oxygen species (ROS). ROS were measured by electron paramagnetic resonance (ESR) using POBN and DMPO spin traps, and by gas chromatography (GC) of ethylene released by ROS-induced α-keto-γ-(methylthio)butyric acid (KMB) oxidation. The oxygen consumption significantly decreased with the number of A/R cycles, and POBN-ESR spectra were specific of adducts formed in the cells from superoxide anion. After a one-hour A/R cycle, high intensity DMPO-ESR spectra were observed and assigned to superoxide anion trapping; the GC results confirmed an important production of ROS compared to normoxic cells. These results show that A/R induces mitochondrial alterations in endothelial cells, and strongly stimulates their oxidative activity as demonstrated by ESR and GC methods.

Azelnidipine prevents cardiac dysfunction in streptozotocin-diabetic rats by reducing intracellular calcium accumulation, oxidative stress and apoptosis

BACKGROUND

Numerous evidences suggest that diabetic heart is characterized by compromised ventricular contraction and prolonged relaxation attributable to multiple causative factors including calcium accumulation, oxidative stress and apoptosis. Therapeutic interventions to prevent calcium accumulation and oxidative stress could be therefore helpful in improving the cardiac function under diabetic condition.

METHODS

This study was designed to examine the effect of long-acting calcium channel blocker (CCB), Azelnidipine (AZL) on contractile dysfunction, intracellular calcium (Ca2+) cycling proteins, stress-activated signaling molecules and apoptosis on cardiomyocytes in diabetes. Adult male Wistar rats were made diabetic by a single intraperitoneal (IP) injection of streptozotocin (STZ). Contractile functions were traced from live diabetic rats to isolated individual cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR90), maximal velocity of shortening/relengthening (± dL/dt) and intracellular Ca2+ fluorescence.

RESULTS

Diabetic heart showed significantly depressed PS, ± dL/dt, prolonged TPS, TR90 and intracellular Ca2+ clearing and showed an elevated resting intracellular Ca2+. AZL itself exhibited little effect on myocyte mechanics but it significantly alleviated STZ-induced myocyte contractile dysfunction. Diabetes increased the levels of superoxide, enhanced expression of the cardiac damage markers like troponin I, p67phox NADPH oxidase subunit, restored the levels of the mitochondrial superoxide dismutase (Mn-SOD), calcium regulatory proteins RyR2 and SERCA2a, and suppressed the levels of the anti-apoptotic Bcl-2 protein. All of these STZ-induced alterations were reconciled by AZL treatment.

CONCLUSION

Collectively, the data suggest beneficial effect of AZL in diabetic cardiomyopathy via altering intracellular Ca2+ handling proteins and preventing apoptosis by its antioxidant property.

Scorpion envenomation among children: clinical manifestations and outcome (analysis of 685 cases)

Our objective was to characterize both epidemiologically and clinically manifestations after severe scorpion envenomation and to define simple factors indicative of poor prognosis in children. We performed a retrospective study over 13 years (1990-2002) in the medical intensive care unit (ICU) of a university hospital (Sfax-Tunisia). The diagnosis of scorpion envenomation was based on a history of scorpion sting. The medical records of 685 children aged less than 16 years who were admitted for a scorpion sting were analyzed. There were 558 patients (81.5%) in the grade III group (with cardiogenic shock and/or pulmonary edema or severe neurological manifestation [coma and/or convulsion]) and 127 patients (18.5%) in the grade II group (with systemic manifestations). In this study, 434 patients (63.4%) had a pulmonary edema, and 80 patients had a cardiogenic shock; neurological manifestations were observed in 580 patients (84.7%), 555 patients (81%) developed systemic inflammatory response syndrome (SIRS), and 552 patients (80.6%) developed multi-organ failure. By the end of the stay in the ICU, evolution was marked by the death in 61 patients (8.9%). A multivariate analysis found the following factors to be correlated with a poor outcome: coma with Glasgow coma score ≤ 8/15 (odds ratio [OR] = 1.3), pulmonary edema (OR = 2.3), and cardiogenic shock (OR = 1.7). In addition, a significant association was found between the development of SIRS and heart failure. Moreover, a temperature > 39°C was associated with the presence of pulmonary edema, with a sensitivity at 20.6%, a specificity at 94.4%, and a positive predictive value at 91.7%. Finally, blood sugar levels above 15 mmol/L were significantly associated with a heart failure. In children admitted for severe scorpion envenomation, coma with Glasgow coma score ≤ 8/15, pulmonary edema, and cardiogenic shock were associated with a poor outcome. The presence of SIRS, a temperature > 39°C, and blood sugar levels above 15 mmol/L were associated with heart failure.

Effects of transgenic endothelin-2 overexpression on diabetic cardiomyopathy in rats

BACKGROUND

Transgenic overexpression of human endothelin-2 in rats was used to characterize the contribution of endothelin to diabetic cardiomyopathy.

MATERIALS AND METHODS

Diabetes mellitus was induced by streptozotocin in transgenic rats and transgene-negative controls. Nondiabetic animals were included as well to form a 4-group study design. Heart morphological and molecular alterations were analysed following 6 months of hyperglycaemia.

RESULTS

Plasma endothelin concentrations were significantly higher in both transgenic groups than in wild-type groups (nondiabetic: 3.5 +/- 0.4 vs. 2.1 +/- 0.2, P < 0.05; diabetic: 4.5 +/- 0.4 vs. 2.5 +/- 0.4 fmol mL(-1), P < 0.01). Diabetes induced cardiac hypertrophy in both wild-type and transgenic rats and showed the highest myocardial interstitial tissue volume density in diabetic transgenic rats (1.5 +/- 0.07%) as compared with nondiabetic transgenic (1.1 +/- 0.03%), nondiabetic wild-type (0.8 +/- 0.01%) and diabetic wild-type rats (1.1 +/- 0.03%; P < 0.01 for all comparisons). A similar pattern with the most severe changes in the enothelin-2 transgenic, diabetic animals was observed for hypertrophy of the large coronary arteries and the small intramyocardial arterioles respectively. Cardiac mRNA expression of endothelin-1, endothelin receptors type A and B were altered in some degree by diabetes or transgenic overexpression of endothelin-2, but not in a uniform manner. Blood pressure did not differ between any of the four groups.

CONCLUSIONS

Overexpression of the human endothelin-2 gene in rats aggravates diabetic cardiomyopathy by more severe coronary and intramyocardial vessel hypertrophy and myocardial interstitial fibrosis. This transgenic intervention provides further and independent support for a detrimental, blood pressure-independent role of endothelins in diabetic cardiac changes.

Total triterpene acids, active ingredients from Fructus Corni, attenuate diabetic cardiomyopathy by normalizing ET pathway and expression of FKBP12.6 and SERCA2a in streptozotocin-rats

Total triterpene acids (TTAs) isolated from Cornus officinalis Sieb., one of the herbs contained in Liuwei Dihuang decoction, were aimed at alleviating diabetic cardiomyopathy. We hypothesized that the benefits of TTAs may result from suppressing the endothelin-reactive oxidative species (ET-ROS) pathway in the myocardium. Diabetes was produced by a single injection of streptozotocin (STZ, 60 mg kg−1, i.p.) in rats. Assessment of cardiac function, calcium handling proteins, endothelin-1 (ET-1) and redox system was conducted 8 weeks after STZ injection. Medication with TTAs (50 mg kg−1, i.g.) was installed in the last 4 weeks. The compromised cardiac function was characterized by depressed contractility (LVSP and LV+dp/dtmax) and relaxation (LVEDP and -LVdp/dtmin) in association with hyperglycaemia (30.2 ± 2.6 mmol L−1) in STZ-injected rats. Down-regulated expression of FKBP12.6 (calstabin 2), sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) and phospholamban (PLB) were also found. These changes occurred in connection with an increased ET-1, up-regulated mRNA of propreET-1 and endothelin converting enzyme (ECE), and a state of oxidant stress was found by increased malondialdehyde (MDA), decreased superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activity, and an enhanced activity and expression of inducible nitric oxide synthase (iNOS) in the diabetic myocardium. After 4 weeks of treatment with TTAs, these changes were alleviated dramatically despite a mild reduction in hyperglycaemia (26.9 ± 3.4 mmol L−1). In conclusion, TTAs, as active ingredients of Liuwei Dihuang decoction, alleviated diabetic cardiomyopathy by normalizing the abnormality of FKBP12.6 and SERCA2a and ET-ROS pathway in the myocardium rather than by hypoglycaemic activity.

Perioperative blood glucose management in patients undergoing tumor hepatectomy

STUDY OBJECTIVE

To determine whether our institutional insulin management (modified Atlanta) protocol is efficient and safe in controlling blood glucose levels in the perioperative period in surgical patients undergoing tumor hepatectomy.

DESIGN

Retrospective study.

SETTING

Large community hospital.

PATIENTS

20 consecutive patients undergoing liver resection for hepatocellular carcinoma, liver metastasis, or other hepatobiliary tumors.

INTERVENTIONS AND MEASUREMENTS

All patients continuously received intravenous glucose (5% dextrose in water, one mL/kg/hr); insulin was administered according to a strict algorithm, and dose adjustments were based on measurements of whole-blood glucose intraoperatively at one-hour intervals, and in the intensive care unit (ICU). Lower and upper blood glucose limits were set at 85 mg/dL and 110 mg/dL, respectively, in the operating room (OR). In the ICU, lower and upper limits were 90 mg/dL and 140 mg/dL, respectively.

MAIN RESULTS

Intraoperatively, 51.3% of measurements were within the target range. In the ICU, 75.2% of measurements showed a blood glucose level of 90 - 140 mg/dL. Two of 78 (2.6%) and two of 363 (0.5%) measurements had a blood glucose level < 70 mg/dL in the OR and ICU, respectively. The lowest blood glucose levels were 65 mg/dL (OR) and 66 mg/dL (ICU).

CONCLUSIONS

The modified Atlanta protocol is efficient and safe in controlling blood glucose levels in the perioperative period of hepatic tumor resection. Because of decreased insulin needs in the ICU, the use of a more liberal algorithm successfully reduced the risk of hypoglycemia.

Inadequate blood glucose control is associated with in-hospital mortality and morbidity in diabetic and nondiabetic patients undergoing cardiac surgery

BACKGROUND

Derangement of glucose metabolism after surgery is not specific to patients with diabetes mellitus. We investigated the effect of different degrees of blood glucose control (BGC) on clinical outcomes after cardiac surgery.

METHODS AND RESULTS

We analyzed 8727 adults operated on between April 1996 and March 2004. The highest blood glucose level recorded over the first 60 hours postoperatively was used to classify patients as having good (<200 mg/dL), moderate (200 to 250 mg/dL), or poor (>250 mg/dL) BGC; 7547 patients (85%) had good, 905 (10%) had moderate, and 365 (4%) had poor BGC. Patients with inadequate BGC were more likely to present with advanced New York Heart Association class, congestive heart failure, hypertension, renal dysfunction, and ejection fraction <50% (P0<or=.001). We found that 52% of patients with poor, 31% with moderate, and 8% with good BGC had diabetes mellitus. Inadequate BGC, but not diabetes mellitus (P=0.79), was associated with in-hospital mortality (good, 1.8%; moderate, 4.2%; poor, 9.6%; adjusted odds ratio: poor versus good BGC, 3.90 [95% confidence interval, 2.47 to 6.15]; moderate versus good BGC, 1.68 [95% confidence interval, 1.25 to 2.25]). Inadequate BGC also was associated with postoperative myocardial infarction (eg, odds ratio, poor versus good BGC: 2.73 [95% confidence interval, 1.74 to 4.26]) and with pulmonary and renal complications in patients without known diabetes mellitus (eg, odds ratio, poor versus good BGC: 2.27 [95% confidence interval, 1.65 to 3.12] and 2.82 [95% confidence interval, 1.54 to 5.14] respectively).

CONCLUSIONS

More than 50% of patients with moderate to poor BGC after cardiac surgery were not previously identified as diabetic. Inadequate postoperative BGC is a predictor of in-hospital mortality and morbidity.

Critical role of angiopoietins/Tie-2 in hyperglycemic exacerbation of myocardial infarction and impaired angiogenesis

Angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) are the two ligands of the Tie-2 receptor, a receptor tyrosine kinase that is expressed on the endothelium. A balanced angiopoietin/Tie-2 system is critical for the maintenance of vascular integrity. We investigated the potential role of a disrupted angiopoietin/Tie-2 system on hyperglycemic exacerbation of myocardial infarction and impaired angiogenesis. Using streptozotocin (STZ) mice subjected to myocardial ischemia, we examined the effects of shifting the Ang-2-to-Ang-1 ratio on myocardial infarction size, apoptosis, bone marrow (BM) cell-endothelial progenitor cell (EPC) differentiation, and angiogenesis. In control mice, myocardial ischemia increased expression of both Ang-2 and Tie-2. In STZ mice, Ang-2 expression was elevated, whereas Tie-2 expression was reduced, and neither was significantly altered by ischemia. Myocardial infarct size and apoptosis were increased in STZ compared with control mice. Using in vivo administration of an adenovirus containing Ang-1 or Ang-2, we found that shifting the Ang-2-to-Ang-1 ratio to favor Ang-1 reduced myocardial apoptosis and infarct size in STZ mice, while shifting the Ang-2-to-Ang-1 ratio to favor Ang-2 resulted in a significant increase in myocardial infarct size and apoptosis in control mice. Myocardial ischemia-stimulated BM cell-EPC differentiation was inhibited and myocardial angiogenesis was reduced in STZ mice. Systemic administration of Ad-Ang-1 restored BM cell-EPC differentiation and increased myocardial VEGF expression and angiogenesis in STZ mice. Our data demonstrate that disturbed angiopoietin/Tie-2 signaling contributes to the hyperglycemic exacerbation of myocardial infarction and impaired angiogenesis. Restoration of the Ang-2-to-Ang-1 ratio may be a novel therapeutic strategy for the treatment of diabetic myocardial ischemic diseases.

The role of endothelin in the cerebrovascular response following intracerebral haemorrhage: experimental studies using the endothelin antagonist SB209670

Primary intracerebral haemorrhage (ICH) is associated with considerable morbidity and mortality. Local endothelin release following ICH may contribute to the pathophysiology of perilesional ischaemia. In diabetics, endothelin release can be enhanced by hyperglycaemia and cerebrovascular dilation may be inhibited by vascular endothelial dysfunction. To examine the effects of endothelin-mediated vasoconstriction after spontaneous ICH in the normal and diabetic brain, regional cerebral blood flow (rCBF) was examined in insulin dependent BB-rats and non-diabetic BB control rats. These experiments were performed 24 h following experimental ICH in both groups of animals that were either given the endothelin antagonist SB209670 or saline. Perilesional oligaemia was similar in control and SB209670 treated diabetic rats, but SB209670 reduced perilesional oligaemia in normal rats. In brain contralateral to the experimental ICH, rCBF was increased by SB209670 in diabetic rats, but not in non-diabetic rats. These studies show that there are differences in the cerebrovascular effects of endothelin in perilesional and contralateral brain in non-diabetic and diabetic rats following ICH.

Acute hyperglycemia exacerbates myocardial ischemia/reperfusion injury and blunts cardioprotective effect of GIK

There is a close association between hyperglycemia and increased risk of mortality after acute myocardial infarction (AMI). However, whether acute hyperglycemia exacerbates myocardial ischemia/reperfusion (MI/R) injury remains unclear. We observed the effects of acute hyperglycemia on MI/R injury and on the cardioprotective effect of glucose-insulin-potassium (GIK). Male rats were subjected to 30 min of myocardial ischemia and 6 h of reperfusion. Rats were randomly received one of the following treatments (at 4 ml.kg(-1).h(-1) iv): Vehicle, GIK (GIK during reperfusion; glucose: 200g/l, insulin: 60 U/l, KCL: 60 mmol/l), HG (high glucose during ischemia; glucose:500 g/l), GIK + HG (HG during I and GIK during R) or GIK + wortmannin (GIK during R and wortmannin 15 min before R). Blood glucose, plasma insulin concentration and left ventricular pressure (LVP) were monitored throughout the experiments. Hyperglycemia during ischemia not only significantly increased myocardial apoptosis (23.6 +/- 1.7% vs. 18.8 +/- 1.4%, P < 0.05 vs. vehicle), increased infarct size (IS) (45.6 +/- 3.0% vs. 37.6 +/- 2.0%, P < 0.05 vs. vehicle), decreased Akt and GSK-3beta phosphorylations (0.5 +/- 0.2 and 0.6 +/- 0.1% fold of vehicle, respectively, P < 0.05 vs. vehicle) following MI/R, but almost completely blocked the cardioprotective effect afforded by GIK, as evidenced by significantly increased apoptotic index (19.1 +/- 2.0 vs. 10.3 +/- 1.2%, P < 0.01 vs. GIK), increased myocardial IS (39.2 +/- 2.8 vs. 27.2 +/- 2.1%, P < 0.01 vs. GIK), decreased Akt phosphorylation (1.1 +/- 0.1 vs. 1.7 +/- 0.2%, P < 0.01 vs. GIK) and GSK-3beta phosphorylation (1.4 +/- 0.2 vs. 2.3 +/- 0.2%, P < 0.05 vs. GIK). Hyperglycemia significantly exacerbates MI/R injury and blocks the cardioprotective effect afforded by GIK, which is, at least in part, due to hyperglycemia-induced decrease of myocardial Akt activation.

Effect of intraoperative hyperglycemia during liver transplantation

BACKGROUND

Intensive blood glucose management has been shown to decrease mortality and infections for intensive care patients. The effect of intraoperative strict glucose control on surgical outcomes, including liver transplantation, has not been well evaluated.

MATERIALS AND METHODS

A retrospective review of all adult liver recipients transplanted between January 1, 2004 and July 6, 2006 was performed. Donor and recipient demographics, intraoperative variables, and outcomes were collected. Intraoperative glucose measurements were performed by the anesthesiology team and treated with intravenous insulin bolus or continuous infusion. Patients with strict glycemic control (mean blood glucose <150 mg/dL) were compared with those with poor control (mean blood glucose >or=150 mg/dL).

RESULTS

During the study period, a total of 184 patients met criteria for analysis. Recipients with strict glycemic control (n=60) had a mean glucose of 135 mg/dL compared with 184 mg/dL in the poorly controlled group (n=124). Other than recipient age (strict versus poor control, 47 +/- 2 y versus 53 +/- 1 y; P<0.01), both groups had similar donor and recipient characteristics. Although the incidence of most postoperative complications were similar, poor glycemic control was associated with a significantly increased infection rate at 30 d posttransplant (48% versus 30%; P=0.02), and also an increased 1 y mortality (21.9% versus 8.8%; P=0.05).

CONCLUSIONS

Intraoperative hyperglycemia during liver transplantation was associated with an increased risk of postoperative infection and mortality. Strict intraoperative glycemic control, possibly using insulin infusions, may improve outcomes following liver transplantation.

Alterations in myocardial metabolism in the diabetic myocardium

Free fatty acids are the preferred substrate for the myocardium. However, under conditions of ischemia, glucose becomes the primary myocardial energy source. Its metabolism avoids the toxic end-products of free fatty acids, which include oxygen free radicals. Patients with diabetes mellitus have impaired uptake of glucose. As a consequence the diabetic myocardium relies heavily on free fatty acid metabolism as its energy source. The results of these alterations in myocardial metabolism ultimately contribute to changes in endothelial function, inflammation, and oxidative stress. This review describes the defects in diabetic myocardial metabolism and how they contribute to cardiovascular dysfunction. The mechanisms by which intravenous insulin infusions can be used to modulate these changes in myocardial metabolism to improve clinical outcomes are discussed.

Selective Endothelin-A Receptor Inhibition After Cardiac Surgery: A Safety and Feasibility Study

BACKGROUND

Increased synthesis and release of the bioactive peptide endothelin has been shown to change hemodynamics and postoperative recovery after cardiac surgery. However, the clinical effects of selective interruption of endothelin signaling have not been studied. Because the endothelin-A (ET-A) receptor subtype is the primary cardiovascular effector for endothelin, this study used the ET-A receptor antagonist sitaxsentan sodium (TBC11251Na) to evaluate: (1) dose-dependent changes in pulmonary artery pressure (PAP) and pulmonary (PVRI) and systemic (SVRI) vascular resistance index in patients undergoing on-pump coronary revascularization; and (2) whether ET-RA administration was associated with increased adverse events.

METHODS

Patients (n = 44, age, 62 +/- 1 years) were randomized to receive vehicle (n = 9) or different bolus infusions of ET-A receptor antagonist: 0.1 (n = 9), 0.5 (n = 9) 1.0 (n = 9), and 2.0 mg/kg (n = 8) at separation from cardiopulmonary bypass (CPB). Adverse events were tabulated until hospital discharge. Results were expressed as changes from a composite baseline value, or from time 0 due to a high degree of intrapatient measurement variability in the postoperative period.

RESULTS

PAP increased by 27% +/- 13% from baseline (19 +/- 1 mm Hg) in the vehicle group at 6 hours post-CPB (p < 0.05). PAP fell from this post-CPB vehicle value in a dose-dependent manner with the ET-A receptor antagonist; with a significant reduction observed at 2 mg/kg (7% +/- 8% increase from baseline, p < 0.05). PVRI was reduced by 28.6% +/- 16% from baseline (249 +/- 22 dyn x s x cm(-5) x m(-2)) in the 2 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB and remained reduced up to 6 hours post-CPB (p < 0.05). SVRI was reduced from baseline (2770 +/- 106 dyn x s x cm(-5) x m(-2)) by 51% +/- 6% in the 2.0 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB (p < 0.05) and remained reduced up to 6 hours post-CPB. A total of 203 adverse events were tabulated in the postoperative period and were equally distributed across the five treatment groups, with no direct attributions to ET-A receptor antagonist treatment.

CONCLUSIONS

This unique study demonstrates that heightened endothelin-A receptor activation contributes to hemodynamic changes in patients after CPB. Selective inhibition of the endothelin receptor system can be successfully and safely performed in patients undergoing cardiac surgery and thereby reveals a potential, and clinically relevant therapeutic target.

Intensive insulin therapy in the intensive cardiac care unit

Treatment in the intensive cardiac care unit (ICCU) enables rigorous control of vital parameters such as heart rate, blood pressure, body temperature, oxygen saturation, serum electrolyte levels, urine output and many others. The importance of controlling the metabolic status of the acute cardiac patient and specifically the level of serum glucose was recently put in focus but is still underscored. This review aims to explain the rationale for providing intensive control of serum glucose levels in the ICCU, especially using intensive insulin therapy and summarizes the available clinical evidence suggesting its effectiveness.

Insulin-based regimens decrease mortality rates in critically ill patients: a systematic review

OBJECTIVES

To determine whether treatment with glucose-insulin-potassium (GIK), insulin and glucose, or insulin by itself is beneficial in limiting organ damage after acute myocardial infarction (AMI) and reducing mortality and morbidity among critically ill hyperglycaemic patients.

METHODS

Systematic review of randomized controlled trials.

MAIN OUTCOME MEASURE

To assess whether tight glycaemic control reduces morbidity and mortality.

STUDIES REVIEWED

Randomized controlled trials of insulin-based regimens in the treatment of critically ill patients.

RESULTS

Nine hundred and twenty-four potentially relevant studies were identified and screened for retrieval. Of these, 16 randomized controlled trials met the inclusion criteria (Table 1). Ten studies examined the effects of GIK, and six of these studies reported a mortality reduction with GIK treatment in addition to enhanced myocardial performance. Five studies examined the administration of insulin. Among these studies, tight glycaemic control of blood glucose in one study was shown to reduce morbidity and mortality of patients in intensive care. Only one study examined insulin/glucose therapy, and it showed a post-myocardial infarction mortality reduction of one year.

CONCLUSIONS

There is increasing evidence that maintaining normoglycaemia and treatment with insulin-based regimens is beneficial in limiting organ damage and significantly reduces both morbidity and mortality in critically ill patients who require intensive care therapy.

A novel endothelin receptor antagonist CPU0213 improves diabetic cardiac insufficiency attributed to up-regulation of the expression of FKBP12.6, SERCA2a, and PLB in rats

The depressed sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a) and Ca2+-release channels (ryanodine receptor RyR2) are involved in the diabetic cardiomyopathy. However, an implication of a down-regulation of FK506-binding protein or calstabin-2 (FKBP12.6) is undefined. It was hypothesized that the down-regulation of FKBP12.6 and SERCA2a of the intracellular calcium handling system is closely related to an up-regulated endothelin (ET) system. An ET receptor antagonist CPU0213 is newly discovered and expected to ameliorate cardiac insufficiency which is mediated by the depressed FKBP12.6 and SERCA2a in diabetic rat heart. Diabetes was developed in male Sprague-Dawley rats 8 weeks after an injection of streptozotocin (60 mg/kg IP), and CPU0213 was instituted 30 mg/kg, SC in the last 4 weeks. The assessment of the cardiac function, cardiac calcium handling proteins, endothelin system, and redox enzyme system were conducted. The compromised cardiac function in diabetic rats was accompanied by a significant down-regulation of expression of FKBP12.6 as well as SERCA2a and phospholamban. These were closely linked with an increased ET-1 and up-regulation of endothelin converting enzyme, PropreET1, and inducible nitric oxide synthase mRNA in diabetic cardiomyopathy. After 4-week treatment, CPU0213 was capable to attenuate completely the down-regulated FKBP12.6 and SERCA2a, and up-regulated ET system in association with a recovery of the cardiac insufficiency of diabetic cardiomyopathy.

Suppression of nitrative damage by metallothionein in diabetic heart contributes to the prevention of cardiomyopathy

Diabetic cardiomyopathy has become a major contributor to the increased mortality of diabetic patients. Although the development and progression of diabetic cardiomyopathy are considered to be associated with diabetes-derived oxidative stress, the precise mechanisms for and effectively preventive approaches to diabetic cardiomyopathy remain to be explored. Recent studies showed that reactive oxygen or nitrogen species (ROS/RNS) not only play a critical role in the initiation of diabetic cardiomyopathy, but also play an important role in physiological signaling. Therefore, this review will first discuss the dual roles of ROS/RNS in the physiological signaling and pathogenic remodeling leading to cardiomyopathy under diabetic conditions. The significant prevention of diabetic cardiomyopathy by metallothionein (MT) as a potent and nonspecific antioxidant will be also summarized. It is clearly revealed that although dual roles of peroxynitrite-nitrated proteins have been indicated under both physiological and pathogenic conditions, suppression of nitrative damage by MT in the diabetic heart is the major mechanism responsible for its prevention of diabetic cardiomyopathy. Finally the potential for clinical enhancement of the cardiac MT expression to prevent or delay the occurrence of cardiomyopathy in diabetic patients will also be addressed.

Factors associated with pulmonary edema in severe scorpion sting patients--a multivariate analysis of 428 cases

OBJECTIVE

To determine clinical and routine laboratory factors associated with pulmonary edema secondary to scorpion envenomation.

DESIGN AND SETTING

Retrospective study covering 13 years (1990-2002) in the medical Intensive Care Unit of a university hospital (Sfax-Tunisia).

PATIENTS

428 patients older than 3 years who were admitted to the intensive care unit for scorpion envenomation were included in this study. Patients were stratified into two groups according to the presence or absence of pulmonary edema as assessed by a medical committee.

MEASUREMENTS AND RESULTS

The mean (+/- SD) age was 17.5 +/- 17.7 years, ranging from 3 to 76 years. The pulmonary edema group included 294 patients (68.7%). A multivariate analysis found the following factors to be correlated with a pulmonary edema: age less than 5 years (p = 0.04), sweating (p = 0.004), agitation (p = 0.01), leukocytes of 25000 cells/mm3 or more (p = 0.02), and a plasma protein concentration of 72 g/L or more (p < 0.0001). In addition, a plasma protein concentration of 72 g/L or more predicted the presence of pulmonary edema with a sensitivity of 78% a specificity of 88%, a positive predictive value of 93%, and negative predictive value of 64%. Almost 84% of patients having a respiratory rate of > or = 30 breaths/minute associated with agitation and sweating were classified in the pulmonary edema group. This clinical association indicates the presence of pulmonary edema with a specificity of 84.3% and a positive predictive value of 87.5%.

CONCLUSION

In scorpion envenomation patients older than 3 years, the association of a respiratory rate of > or = 30 breaths/minute, agitation, sweating, or the presence of high plasma protein concentrations suggest the presence of pulmonary edema.

Natriuretic Peptides in the Perioperative Management of Cardiac Surgery Patients

Both heart failure (HF) and cardiac surgery with cardiopulmonary bypass result in a release of neurohormones, with a variety of physiologic effects. Administration of exogenous B-type natriuretic peptide (BNP) has beneficial hemodynamic effects and reduces the level of several neurohormones in HF patients. BNP is currently being investigated in the perioperative management of cardiac surgery patients and may be especially beneficial for patients with ventricular dysfunction, pulmonary hypertension, or renal dysfunction. Using a neurohormonal approach to supportive therapy may enhance future strategies for patients undergoing cardiac surgery, especially those at greatest risk for complications.

[Cardiovascular dysfunction following severe scorpion envenomation. Mechanisms and physiopathology]

The seriousness of scorpion envenomation results essentially from left cardiac function with pulmonary oedema and/or a state of shock. Adrenergic myocarditis, toxic myocarditis and myocardial ischemia are the 3 mechanisms that explain the cardiac dysfunction. Myocardial ischemia is not only due to the release of catecolamines but also the effect of the cytokines and/or neuropeptide Y on the coronary vessels. The cardiac damage can be due or enhanced by the depressive effect of the cytokines on the myocardial cells. The frequently observed hyperglycaemia only enhances the state of the already damaged myocardium.

Tight glycemic control in diabetic coronary artery bypass graft patients improves perioperative outcomes and decreases recurrent ischemic events

BACKGROUND

This study sought to determine whether tight glycemic control with a modified glucose-insulin-potassium (GIK) solution in diabetic coronary artery bypass graft (CABG) patients would improve perioperative outcomes.

METHODS AND RESULTS

One hundred forty-one diabetic patients undergoing CABG were prospectively randomized to tight glycemic control (serum glucose, 125 to 200 mg/dL) with GIK or standard therapy (serum glucose <250 mg/dL) using intermittent subcutaneous insulin beginning before anesthesia and continuing for 12 hours after surgery. GIK patients had lower serum glucose levels (138+/-4 versus 260+/-6 mg/dL; P<0.0001), a lower incidence of atrial fibrillation (16.6% versus 42%; P=0.0017), and a shorter postoperative length of stay (6.5+/-0.1 versus 9.2+/-0.3 days; P=0.003). GIK patients also showed a survival advantage over the initial 2 years after surgery (P=0.04) and decreased episodes of recurrent ischemia (5% versus 19%; P=0.01) and developed fewer recurrent wound infections (1% versus 10%, P=0.03).

CONCLUSIONS

Tight glycemic control with GIK in diabetic CABG patients improves perioperative outcomes, enhances survival, and decreases the incidence of ischemic events and wound complications.

Tetrahydrobiopterin attenuates homocysteine induced endothelial dysfunction

Homocysteine is an independent risk factor for atherosclerotic vascular disease. It impairs endothelial function via increasing superoxide production and quenching nitric oxide (NO) release. Tetrahydrobiopterin (BH4) is a critical cofactor that couples nitric oxide synthase and facilitates the production of nitric oxide (vs. superoxide anions). In the first study, the effects of hyperhomocysteinemia (0.1 mM, 3 h) on endothelium-dependent vasorelaxation to ACh and A23187 were examined in isolated segments of rat aortae in the presence or absence of BH4 (0.1 mM). In the second study, the effects of hyperhomocysteinemia (24 h) on nitric oxide production and superoxide release (using lucigenin chemiluminescence) were studied in human umbilical vein endothelial cells in the absence or presence of BH4 (10 microM). Homocysteine incubation impaired receptor-dependent and -independent endothelial function to ACh and A23187. This effect was attenuated by BH4. Furthermore, homocysteine exposure increased superoxide production and impaired agonist-stimulated nitric oxide release. These effects were attenuated by BH4 (p < 0.05). Hyperhomocysteinemia impairs endothelial function, in part due to a diminished bioavailability of BH4 with resultant uncoupling of nitric oxide synthase. BH4 may represent an important target for strategies aimed at improving endothelial dysfunction secondary to hyperhomocysteinemia.

Metabolic and nutritional support in acute cardiac failure

PURPOSE OF REVIEW

Cardiovascular disease is one of the most important causes of morbidity and mortality in western countries, generating an increasing number of admissions to intensive care units. Cardiac failure has long been associated with nutritional disorders, malnutrition and cachexia being frequent during the late phases of congestive heart failure: undernutrition is also a determinant of outcome, even after cardiac transplantation.

RECENT FINDINGS

It has been shown that early metabolic support can improve the recovery of the ischaemic heart. This paper reviews recent findings on substrates that can support the failing myocardium, which are mainly glucose-insulin, glutamine, taurine, selenium, thiamine, folic acid, and omega-3 fatty acids. Ischaemia-reperfusion generates tissue lesions that can be partly prevented through substrate manipulation.

SUMMARY

Shifting the substrate metabolism from lipids to carbohydrates and reinforcing the antioxidant status reduces the deleterious biological and clinical consequences of acute ischaemic events. The use of the glucose-insulin-potassium infusion has become widespread with the re-discovery of its value in modulating cellular metabolism and accelerating recovery of the ischaemic myocardium. Antioxidants have gained acceptance in the perioperative phase, as well as in chronic heart failure. This constitutes another piece of evidence in favour of early metabolic and nutritional intervention. There also appears to be room for the prevention of acute deterioration of cardiac function after surgery with the preoperative administration of oral supplements containing omega-3 fatty acids.