Reduced glucose transporter GLUT4 in skeletal muscle predicts insulin resistance in non-diabetic chronic heart failure patients independently of body composition.

BACKGROUND: In chronic heart failure (CHF) skeletal muscle insulin resistance occurs independently of etiology and contributes to impaired energy metabolism. GLUT4, the predominant glucose transporter in the skeletal muscle promotes the rate-limiting step of glucose utilization in skeletal muscle. The significance of skeletal muscle GLUT4 in patients with CHF has not been studied in detail. METHODS: In patients with CHF and free of diabetes mellitus (n=29; mean NYHA class 2.3+/-0.1, peak VO(2) 18.8+/-1.1 mL/kg/min) and healthy control subjects of similar age (n=7), GLUT4 protein was assessed from percutaneous skeletal muscle biopsies. Skeletal muscle insulin sensitivity was assessed by intravenous glucose tolerance testing using a minimal modeling technique. Body composition was analyzed by dual energy X-ray absorptiometry (DEXA) scanning. RESULTS: Skeletal muscle GLUT4 was lower in CHF patients than in controls (0.75+/-0.07 vs 1.24+/-0.19 density units, P<0.01) and decreased in parallel to severity of CHF, being lowest in NYHA III/IV (0.596+/-0.08, ANOVA P<0.01 vs controls). GLUT4 was lower in patients with an ischemic etiology compared to dilated cardiomyopathy and controls (ANOVA P<0.01). Patients and controls were similar for global parameters of body composition (weight: 78+/-4 vs 76+/-4 kg, BMI 25.5+/-0.8 vs 25.8+/-1.5 kg/m(2)), and total tissue amount and regional distribution of fat and lean tissue (all P>0.2). Low GLUT4 predicted impaired insulin sensitivity, i.e. insulin resistance (r=0.55, P<0.01). In multivariate analysis, GLUT4 levels predicted insulin sensitivity independently of age and parameters of body composition (including weight, BMI, and total and regional fat and lean tissue distribution). CONCLUSION: In non-diabetic patients with CHF, skeletal muscle GLUT4 transport protein is reduced in parallel to disease severity, independently of body composition. Low skeletal muscle GLUT4 contributes to insulin resistance in CHF.

Cardiotrophin-1 induces interleukin-6 synthesis in human monocytes.

BACKGROUND: Patients with congestive heart failure (CHF) show increased serum concentrations of cytokines like interleukin-6 (IL-6) and cardiotrophin-1 (CT-1). Additionally, monocyte function is modulated in CHF. The aim of this study was to examine if CT-1 is able to induce IL-6 in human monocytes and to investigate the underlying pathway. METHODS: Separated peripheral blood monocytes of healthy volunteers were cultured with increasing concentrations of CT-1 for different periods. IL-6 mRNA was determined by RT-PCR or real-time PCR and IL-6 protein concentration in the supernatant by ELISA. Phosphorylation of signal transducer and activation of transcription (STAT) 3 was analyzed by western blot or by FACS analysis. To clarify the signalling pathway of CT-1 induced IL-6 expression various inhibitors of possible signal transducing molecules were used. RESULTS: CT-1 induced IL-6 mRNA in monocytes in a time- and concentration-dependent manner. Maximal mRNA induction was detectable after 6h with 100 ng/ml CT-1. IL-6 protein also increased in a time- and concentration-dependent manner with a maximum after 48 h with 100 ng/ml CT-1. AG490 as well as SB 203580 and parthenolide blocked CT-1 induced IL-6 expression completely. AG 490 was able to inhibit STAT3 phosphorylation in western blot analysis completely. This indicates that JAK2/STAT3, p38 and nuclear factor kappaB (NFkappaB) are involved in this pathway. To exclude a possible influence of plastic adherence of monocytes on CT-1 induced IL-6 expression, we determined intracellular STAT3 phosphorylation in whole blood samples by FACS analysis and observed independently of culture conditions a CT-1 concentration-dependent STAT3 phosphorylation. CONCLUSION: CT-1 induces IL-6 mRNA and protein expression in a time- and concentration-dependent manner. The underlying pathway is Janus kinase (JAK)2/STAT3, p38 and NFkappaB dependent. These data may explain increased IL-6 serum concentrations and altered monocyte function found in patients with CHF. Modulation of the CT-1 pathway might be a interesting strategy in the treatment of CHF.

Improvement of the primary success rate of recanalization of chronic total coronary occlusions with the Safe-Cross system after failed conventional wire attempts.

BACKGROUND: In view of the improved long-term patency with drug-eluting stents, the challenge with chronic total coronary occlusion (CTO) remains the low primary success rate. Improved guide wires have increased this rate, but alternative devices may be of additional value. The goal of the present study was to determine the additional benefit of a new penetration device in CTOs after an extensive conventional wire approach. METHODS AND RESULTS: In 148 consecutive patients the recanalization of a CTO of >3 months was attempted. A conventional wire approach was used with recent dedicated recanalization wires, which was successful in 104 patients (70%). If after at least 20 min of fluoroscopic time no crossing of the wire was achieved, the Safe-Cross wire (SC) (Intralumina) was used which enables verification of the intraluminal wire position via optical reflectometry, and crossing of resistent occlusion caps by radiofrequency ablation. Due to severe dissections after the conventional approach, the SC was not used in 10 patients. In 34 patients the SC wire was applied, leading to successful lesion crossing in 14 patients (41%). Thus, the primary success rate was improved from 70.2% to 79.7%. No periprocedural major adverse events were observed with the SC wire. The successful attempts with the SC wire were predominantly in blunt occlusions. All patients with successful wire passage could be treated with one or more stents. CONCLUSIONS: In a real world cohort of patients with CTO, the SC wire could increase the primary success rate after failed extensive conventional wire attempt. In these worst case patients the SC success rate was 41%. This new wire appears to have additional potential in failures of a conventional wire approach.

Analysis of location and pattern of target vessel failure in chronic total occlusions after stent implantation and its potential for the efficient use of drug-eluting stents.

OBJECTIVES: The recanalization of chronic total occlusions (CTOs) is a complex procedure with high rates of target vessel failure (TVF), i.e., restenosis or reocclusion. Little is known about the localization of lesion recurrence, and whether extensive stenting should be performed. In this prospective analysis, the area at high risk for restenoses after recanalization of CTO was localized. METHODS: Angiograms of 97 consecutive patients and control angiograms after a mean period of 5 +/- 1.3 months were analyzed for location and length of the CTO and the sites of recurrences. RESULTS: In total, 158 stents were implanted (1.6 +/- 0.9 per lesion). Restenoses occurred in 39% and reocclusions in 17% of the patients. Patients with a TVF had a longer CTO than patients without TVF (17.9 +/- 10.2 vs 13.9 +/- 8.6 mm; P = 0.023). The TVF rate increased with the number of implanted stents. The stent diameter was smaller in lesions with subsequent reocclusions than in restenotic and nonrestenotic lesions (2.8 +/- 0.5 vs 3.0 +/- 0.4 and 3.2 +/- 0.4 mm resp.; P = 0.007). Analyzing the localization of the 38 restenoses, we only found 45% restricted to the area of the former CTO, while 82% were located in the area of the former CTO plus 10 mm in proximal and distal direction. CONCLUSIONS: Stents should not only cover the site of the CTO, but should enclose the high-risk area of recurrence within 10 mm proximal and distal of the former CTO. This may guide the rational use of drug-eluting stents.

Paclitaxel-eluting stents for the treatment of chronic total coronary occlusions: a strategy of extensive lesion coverage with drug-eluting stents.

The recanalization of a chronic total coronary occlusion (CTO) is hampered by a high rate of lesion recurrence. The goal of the present study is to assess the effect of paclitaxel-eluting stents in CTOs in a strategy of extensive stent coverage and the optional use of additional bare metal stents (BMSs). In 82 consecutive patients, a CTO (duration > 2 weeks) was successfully recanalized with implantation of one or more Taxus stents. These patients underwent a repeat angiography after 5.0 +/- 1.5 months and were assessed by quantitative angiography. The patients were compared with 82 clinically and lesion-matched patients from a consecutive series of 148 patients with CTOs treated by BMS in the preceding time period. In 21 of the 82 patients, additional lesions in the target artery not directly related to the original occlusion site were treated with BMSs (hybrid approach). The history of diabetes, extent of coronary artery disease, clinical symptoms, and angiographic features were similar in the Taxus and BMS group. Periprocedural adverse events were 3.3% with Taxus and 3.3% with BMS, but 12 months MACE was significantly lower in the group with exclusive use of Taxus (13.3% vs. 56.7%; P < 0.001), mainly due to a lower target lesion revascularization of 10.0% as compared to 53.4% (P < 0.001). There was only one late reocclusion with Taxus (1.7%) as compared to 21.7% with BMS (P < 0.05). However, in the hybrid group, the MACE rate was considerably higher, with 33.3%. Our data of a 80% reduction of target vessel failure as compared to BMS, with a lower risk of late reocclusions without increased acute adverse events, demonstrate the benefit of paclitaxel-eluting stents in CTOs. However, diffuse atherosclerosis in CTOs should be covered completely by the drug-eluting stents.

Cardiotrophin-1 induces interleukin-6 synthesis in human umbilical vein endothelial cells.

In patients with chronic heart failure (CHF) increased plasma concentrations of proinflammatory cytokines are found. For example, the plasma interleukin-6 (IL-6) concentration correlates with disease severity. Beside IL-6 cardiotrophin-1 (CT-1), a member of the IL-6 superfamily, is also increased in CHF. We examined whether CT-1 is able to induce IL-6 in human umbilical vein endothelial cells (HUVEC) and characterised the underlying pathway. IL-6 mRNA was determined by real-time PCR and by RT-PCR in HUVEC which were stimulated with different CT-1 concentrations and for different time periods. IL-6 concentration in the supernatant was determined by ELISA. For the pathway determination following inhibitors were used: piceatannol (signal transducer and activation of transcription (STAT)3 phosphorylation), wortmannin (phosphatiylinositol 3-kinase (PI3K)), SB203580 (p38 mitogen-activated protein kinase (MAPK)), AG490 (Janus kinase (JAK)2), PD98059 (mitogen-activated protein kinase kinase (MEK) 1/2), parthenolide (nuclear factor kappaB) and cycloheximide (protein biosynthesis). CT-1 caused a concentration- and time-dependent increase in IL-6 mRNA in HUVEC with a maximal induction seen after 6 h (2-fold compared to control) with 100 ng/ml CT-1. In the supernatant of HUVEC a concentration- and time-dependent increase of IL-6 protein was found. A maximum effect with 100 ng/ml CT-1 was found after 24 h (11-fold compared to control). AG490, SB203580, piceatannol, parthenolide and cycloheximide inhibit CT-1 induced IL-6 mRNA and protein expression whereas wortmannin and PD98059 did not inhibit IL-6 expression. CT-1 induced both IL-6 mRNA and protein in a concentration- and time-dependent manner in HUVEC. The underlying pathway includes activation of JAK2, STAT3, p38 and NFkappaB. CT-1 induced IL-6 expression and requires protein synthesis and IL-6 is not stored intracellularly. We speculate that in CHF CT-1 might be in part responsible for increased IL-6 plasma concentrations. Modulation of the CT-1 pathway may be a further strategy in CHF treatment.

No association between transmembrane protein-tyrosine phosphatase receptor type C (CD45) exon A point mutation (77C>G) and idiopathic dilated cardiomyopathy.

To investigate whether a 77C>G polymorphism in exon A of the CD45 gene causing a variant CD45RA expression pattern is associated with the development of idiopathic dilated cardiomyopathy (DCM), we studied a total of 414 individuals (104 patients and 310 controls). CD45RA expression pattern on lymphocytes was examined by flow cytometric analysis and subsequently the CD45 77C>G polymorphism was genotyped by polymerase chain reaction-allele specific restriction enzyme analysis (PCR-ASRA). We found 5 patients and 8 control individuals displaying the variant CD45RA expression pattern. All identified individuals carried the heterozygous CD45 77C>G polymorphism. The frequency of the 77G allele in the patient group was 2.4%, which was not significantly different from 1.3% found in the control group (p=0.327). In conclusion, the data of this preliminary study could not reveal any association between the CD45 77C>G polymorphism and susceptibility to idiopathic DCM in a German population.

Treatment with granulocyte colony-stimulating factor for mobilization of bone marrow cells in patients with acute myocardial infarction.

BACKGROUND: This study was undertaken to evaluate the hypothesis that treatment with granulocyte colony-stimulating factor (G-CSF) to mobilize bone marrow cells (BMCs) is feasible and safe and promotes neovascularization and myocardial function in patients with acute myocardial infarction. METHODS: Fourteen patients in the treatment group and 9 patients in the control group were enrolled in this prospective, nonrandomized, open-label study. Forty-eight hours after successful recanalization and stent implantation, the patients of the treatment group received 10 microg/kg body weight per day G-CSF subcutaneously for mean treatment duration of 7.0 +/- 1.0 days. Nine patients fulfilled the entry criteria but refused participation and served therefore as control group. In both groups, regional wall motion and perfusion was evaluated with electrocardiogram-gated sestamibi single-photon emission computed tomography imaging and ejection fraction with radionuclidventriculography before discharge and after 3 months. RESULTS: No severe side effects of G-CSF treatment were observed. There was a significant improvement of the regional wall motion and perfusion within the treatment group (P < .0001) and between the treatment and control group (P < .05 and P < .01, respectively). Ejection fraction in the treatment group increased from 0.40 +/- 0.11 to 0.48 +/- 0.13 (P < .01), whereas in the control group, ejection fraction increased from 0.40 +/- 0.13 to 0.43 +/- 0.13 (P = .049). A control angiography of the treatment group after 12.4 +/- 6.6 months showed an in-stent restenosis in 1 patient. CONCLUSION: In patients with acute myocardial infarction, treatment with G-CSF to mobilize BMCs is feasible and safe and seems to be effective under clinical conditions. The therapeutic effect might be attributed to BMC-associated promotion of myocardial regeneration and neovascularization.

The importance of the gastrointestinal system in the pathogenesis of heart failure.

Chronic heart failure (CHF) is a multi-organ disease with increasing evidence for the involvement of the gastrointestinal (GI) system in this syndrome. In recent research, the gut has received very little attention from cardiologists as its role in the pathogenesis of cardiovascular disease is poorly understood. Intestinal ischaemia may play an important role in bacterial translocation by increasing bowel permeability. Decreased cardiac function can reduce bowel perfusion and so clearly impairs the function of the intestinal barrier. There is an increasing evidence to suggest that a 'leaky' bowel wall may lead to translocation of bacteria and/or endotoxin, which may be an important stimulus for inflammatory cytokine activation in CHF. Impaired functioning of the GI system may also contribute to malnutrition and cachexia in CHF. It is hoped that by improving our understanding of the role of the gut in cardiac disease will lead to the development of novel therapeutic strategies in the future.

Outcome after cardiac arrest: predictive values and limitations of the neuroproteins neuron-specific enolase and protein S-100 and the Glasgow Coma Scale.

BACKGROUND AND PURPOSE: Patients resuscitated from cardiac arrest are at risk of subsequent death or poor neurological outcome up to a persistent vegetative state. We investigated the prognostic value of several epidemiological and clinical markers and two neuroproteins, neuron-specific enolase (NSE) and S-100 protein (S-100), in 97 patients undergoing cardiopulmonary resuscitation (CPR) after non-traumatic cardiac arrest between 1998 and 2002. RESULTS: 52.6% of the patients died, 28.8% survived with severe, moderate or without neurological disorders, and 18.6% remained in a persistent vegetative state. Unconsciousness>48 h after CPR predicted a 60.6-fold (95% CI 14.3287-257.205, p=0.001) and a Glasgow Coma Scale (GCS)<6 points after 72 h a 11.2-fold (CI 95%, 3.55-36.44, p<0.001) risk of poor neurological outcome. Serum levels>or=65 ng/ml for NSE and >or=1.5 microg/l for S-100 increased the risk of death and persistent vegetative state 16.8 (95% CI 2.146-131.520)- and 12.6 (95% CI 1.1093-99.210)-fold, respectively. By combination of the GCS with elevated serum concentrations of both neuroproteins above the cut off levels on third day after CPR a poor neurological outcome was predicted with a specificity of 100%. CONCLUSION: The combination of GCS with the serum levels of both neuroproteins at 72 h after CPR permit a more reliable prediction of outcome in post arrest coma than the single markers alone, independent of the application of anaesthetic agents.

Prevention of lesion recurrence in chronic total coronary occlusions by paclitaxel-eluting stents.

OBJECTIVES: The aim of this research was to assess the efficacy of paclitaxel-eluting stents in chronic total coronary occlusions (CTO). BACKGROUND: Percutaneous coronary interventions for CTOs are characterized by a high target vessel failure rate. METHODS: In 48 consecutive patients, paclitaxel-eluting stents (Taxus, Boston Scientific Corp., Natick, Massachusetts) were implanted after successful recanalization of a CTO (duration >2 weeks). Patients underwent an angiography after 6 months and were followed clinically for 12 months. They were compared with 48 lesion- and risk-matched patients with CTOs treated with bare metal stents (BMS). Primary clinical end point was the one-year incidence of major adverse cardiac events (MACE) (death, myocardial infarction, repeat revascularization); secondary end points were the rate of restenosis and re-occlusion. RESULTS: In-hospital MACE was 4.2% with Taxus, and 2.1% with BMS (p = NS). The one-year MACE rate was 12.5% in the Taxus group, and 47.9% in the BMS group (p < 0.001), which was due to a reduced need for repeat revascularization. The angiographic restenosis rate was 8.3% with Taxus versus 51.1% with BMS (p < 0.001). There was only one late re-occlusion with Taxus (2.1%) as compared with 23.4% with BMS (p < 0.005). The late loss was reduced in the Taxus group by 84% as compared with BMS. All nonocclusive restenoses in the Taxus group were focal and successfully treated by implanting an additional Taxus stent. CONCLUSIONS: The treatment of CTOs with a paclitaxel-eluting stent drastically reduces MACE and restenosis, and almost eliminates re-occlusion, which is typically frequent with BMS in CTOs. Chronic total coronary occlusion should be a preferred indication for drug-eluting stents.

Sirolimus-eluting stents for the prevention of restenosis in a worst-case scenario of diffuse and recurrent in-stent restenosis.

For recurrent in-stent restenosis (ISR), surgical revascularization or brachytherapy is still the principal therapeutic options. The present investigation explores the efficacy of a sirolimus-eluting stent to prevent restenosis in these lesions with a high risk of recurrence. In 22 consecutive patients with a recurrent and diffuse ISR, a sirolimus-eluting stent was implanted to cover the restenotic lesion. All patients were followed clinically for at least 1 year and underwent a repeat angiography after 7 months. A quantitative coronary angiographic analysis was done. The target vessel failure was 14% in the sirolimus-eluting stent group, with an angiographic late loss of only 0.39 +/- 0.54. No subacute stent thrombosis was observed, and the 1-year event-free survival was 86%. The three cases with restenosis were all focal and could be successfully treated by additional drug-eluting stent implantation. This study showed the efficacy of a sirolimus-eluting stent for the prevention of restenosis in a worst-case scenario of recurrent and diffuse ISR. The observed restenosis rate is lower than that reported after brachytherapy and suggests that sirolimus-eluting stents are a promising treatment option for ISR.

Growth factors in the collateral circulation of chronic total coronary occlusions: relation to duration of occlusion and collateral function.

BACKGROUND: Despite extensive animal experimental evidence, there are few data on the relation of growth factors and collateral function in humans. METHODS AND RESULTS: In 104 patients with a chronic total coronary occlusion (CTO; >2 weeks' duration), collateral function was assessed invasively during recanalization by intracoronary Doppler and pressure recordings. A collateral resistance index, R(Coll), was calculated. Blood samples were drawn from the distal coronary bed supplied by the collaterals and from the aortic root to measure basic fibroblast growth factor (bFGF), monocytic chemotactic protein-1 (MCP-1), transforming growth factor-beta (TGF-beta), placenta growth factor (PlGF), and tumor necrosis factor-alpha (TNF-alpha). The bFGF concentration in the collateralized artery was higher than in the aortic root (34+/-20 versus 18+/-14 pg/mL; P<0.001). bFGF was highest in recent occlusions (2 to 12 weeks) with the highest R(Coll). Higher collateral concentrations were also observed for MCP-1, TGF-beta, and PlGF, but without a close relation to the duration of occlusion. TNF-alpha was not increased in collaterals compared with the systemic circulation. MCP-1, PlGF, and TGF-beta were significantly increased in small collaterals with the highest shear stress. Diabetic patients had lower bFGF and higher MCP-1 levels than nondiabetics. CONCLUSIONS: In CTOs, the continuous release of bFGF into collaterals showed a close relation to the duration of occlusion and collateral function, which underscores its therapeutic potential. Other factors influencing growth factor release appeared to be shear stress for MCP-1, TGF-beta, and PlGF and the presence of diabetes.

Studies on intragastric PCO2 at rest and during exercise as a marker of intestinal perfusion in patients with chronic heart failure.

AIMS: The aim of this study was to investigate mesenteric ischaemia by determining intragastric PCO(2) (iPCO(2)) with gastric tonometry during rest and exercise stress testing in patients with chronic heart failure (CHF). In CHF inflammatory immune activation is hypothesized to result from a chronic endotoxin challenge due to bacterial translocation of hypoperfused intestinal mucosa. METHODS AND RESULTS: In 10 patients with CHF and ten healthy controls a tonometry catheter was inserted into the stomach. IPCO(2) was measured at rest and during bicycle exercise every 5 min. At rest arterial pCO(2) (aPCO(2)), intragastric pCO(2) (iPCO(2)) and the intragastric/arterial gap did not differ between patients and controls. During low level exercise (25 W), patients showed an increase in iPCO(2) compared to resting iPCO(2), whereas controls did not show an increase in iPCO(2) (change in iPCO(2): 12+/-2% vs. 1+/-0.4%, P<0.001). In CHF, iPCO(2) during peak exercise was 25+/-3% higher than at rest, compared to controls (increase 2+/-1, P<0.0001). CONCLUSIONS: Patients with CHF already at low level exercise develop an increase in iPCO(2). This is likely to reflect hypoperfusion of the intestinal mucosa, which may contribute to the development of bacterial translocation.

Iohexol contrast medium induces QT prolongation in amiodarone patients.

AIMS: Amiodarone is widely used in ventricular tachyarrhythmias and atrial fibrillation, known to prolong QT-intervals. Concurrent administration of drugs prolonging QT- time can induce life-threatening ventricular tachyarrhythmia. METHODS: QT-interval changes following use of Iohexol contrast-medium for coronarangiography were observed comparing 21 patients taking long-term amiodarone therapy with 21 controls not taking amiodarone or QT-prolonging drugs retrospectively. RESULTS: Concurrent use of Iohexol and amiodarone was associated with significant prolongation of QTc-interval (433, 95%CI: 419-448 ms vs. 480, 95%CI: 422-483 ms, P < 0.001) the day after coronarangiograpgy. 6/21 patients showed severe prolonged QTc-interval of >500 ms. CONCLUSION: Caution is advised until more is known about pro-arrhythmic effects of Iohexol.

Carvedilol inhibits platelet-derived growth factor-induced signal transduction in human cardiac fibroblasts.

In the current study, first the platelet-derived growth factor (PDGF)-induced stimulation of the PDGF-beta receptor kinase in human cardiac fibroblasts was examined, and then the possibility of counterbalancing this signal transduction by carvedilol, a beta-blocker with alpha1-blocking properties, was investigated. Human cardiac fibroblasts were cultured from myocardial biopsy samples taken from patients with idiopathic dilated cardiomyopathy. The stimulation of the PDGF-beta receptor kinase by recombinant human PDGF (BB) in the cells and the inhibitory effect of carvedilol (1, 5, 10, and 20 microM) were investigated by analyzing PDGF-induced PDGF receptor tyrosine phosphorylation using Western blotting and by measuring DNA synthesis with a colorimetric assay. In human cardiac fibroblasts, the PDGF receptor kinase could be stimulated with PDGF (100 ng/ml) and inhibited with carvedilol (5 microM). In addition, carvedilol at a concentration of 5 microM significantly decreased DNA synthesis by approximately 50%. The inhibition of PDGF-stimulated mitogenesis by carvedilol at concentrations of 10 and 20 microM was 64 or 75%, respectively. Other beta-adrenoceptor antagonists such as propranolol (10 microM) and metoprolol (10 microM) did not significantly affect the PDGF-induced beta-receptor autophosphorylation. These findings provide novel experimental support for the known beneficial clinical effects of carvedilol in the treatment of chronic heart failure associated with myocardial fibrosis.