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Biomedical subjects

Hugo A Katus

Publications and source records attributed to Hugo A Katus.

At least 55 records · Page 3Linked to original sources
PubMed2006

Real-time myocardial perfusion imaging for pharmacologic stress testing: added value to single photon emission computed tomography.

BACKGROUND: Little is known about the incremental value of real-time myocardial contrast echocardiography (MCE) as an adjunct to pharmacologic stress testing. This study was performed to evaluate the diagnostic value of MCE to detect abnormal myocardial perfusion by technetium Tc 99m sestamibi-single photon emission computed tomography (SPECT) and anatomically significant coronary artery disease (CAD) by angiography. METHODS: Myocardial contrast echocardiography was performed at rest and during vasodilator stress in consecutive patients (N = 120) undergoing SPECT imaging for known or suspected CAD. Myocardial opacification, wall motion, and tracer uptake were visually analyzed in 12 myocardial segments by 2 pairs of blinded observers. Concordance between the 2 methods was assessed using the kappa statistic. RESULTS: Of 1356 segments, 1025 (76%) were interpretable by MCE, wall motion, and SPECT. Sensitivity of wall motion was 75%, specificity 83%, and accuracy 81% for detecting abnormal myocardial perfusion by SPECT (kappa = 0.53). Myocardial contrast echocardiography and wall motion together yielded significantly higher sensitivity (85% vs 74%, P < .05), specificity of 83%, and accuracy of 85% (kappa = 0.64) for the detection of abnormal myocardial perfusion. In 89 patients who underwent coronary angiography, MCE and wall motion together yielded higher sensitivity (83% vs 64%, P < .05) and accuracy (77% vs 68%, P < .05) but similar specificity (72%) compared with SPECT for the detection of high-grade, stenotic (> or = 75%) coronary lesions. CONCLUSION: Assessment of myocardial perfusion adds value to conventional stress echocardiography by increasing its sensitivity for the detection of functionally abnormal myocardial perfusion. Myocardial contrast echocardiography and wall motion together provide higher sensitivity and accuracy for detection of CAD compared with SPECT.

Coronary Artery Disease↗
PubMed2006

Are beta-blockers needed in patients receiving spironolactone for severe chronic heart failure? An analysis of the COPERNICUS study.

BACKGROUND: The beneficial effects of beta-blockers and aldosterone receptor antagonists are now well established in patients with severe systolic chronic heart failure (CHF). However, it is unclear whether beta-blockers are able to provide additional benefit in patients already receiving aldosterone antagonists. We therefore examined this question in the COPERNICUS study of 2289 patients with severe CHF receiving the beta1-beta2/alpha1 blocker carvedilol compared with placebo. METHODS: Patients were divided post hoc into subgroups according to whether they were receiving spironolactone (n = 445) or not (n = 1844) at baseline. Consistency of the effect of carvedilol versus placebo was examined for these subgroups with respect to the predefined end points of all-cause mortality, death or CHF-related hospitalizations, death or cardiovascular hospitalizations, and death or all-cause hospitalizations. RESULTS: The beneficial effect of carvedilol was similar among patients who were or were not receiving spironolactone for each of the 4 efficacy measures. For all-cause mortality, the Cox model hazard ratio for carvedilol compared with placebo was 0.65 (95% CI 0.36-1.15) in patients receiving spironolactone and 0.65 (0.51-0.83) in patients not receiving spironolactone. Hazard ratios for death or all-cause hospitalization were 0.76 (0.55-1.05) versus 0.76 (0.66-0.88); for death or cardiovascular hospitalization, 0.61 (0.42-0.89) versus 0.75 (0.64-0.88); and for death or CHF hospitalization, 0.63 (0.43-0.94) versus 0.70 (0.59-0.84), in patients receiving and not receiving spironolactone, respectively. The safety and tolerability of treatment with carvedilol were also similar, regardless of background spironolactone. CONCLUSION: Carvedilol remained clinically efficacious in the COPERNICUS study of patients with severe CHF when added to background spironolactone in patients who were practically all receiving angiotensin-converting enzyme inhibitor (or angiotensin II antagonist) therapy. Therefore, the use of spironolactone in patients with severe CHF does not obviate the necessity of additional treatment that interferes with the adverse effects of sympathetic activation, specifically beta-blockade.

Adrenergic beta-Antagonists↗
PubMed2006

Preserved norepinephrine reuptake but reduced sympathetic nerve endings in hypertrophic volume-overloaded rat hearts.

BACKGROUND: In congestive heart failure (CHF), an activation of the cardiac sympathetic nervous system results in depleted cardiac norepinephrine (NE) stores. The underlying regulatory mechanisms are discussed controversially and were investigated in the present study in CHF resulting from volume overload. METHODS AND RESULTS: Aorto-caval shunt (AVS) was performed in rats. Plasma NE levels were determined by radioenzymatic assay, left ventricular NE by high-performance liquid chromatography, endothelin-1 by enzyme-linked immunosorbent assay. Tyrosine-hydroxylase (TH)- and nerve growth factor (NGF)-mRNA was determined by Northern blot analysis and ribonuclease-assay. Cardiac [3H]-NE uptake was measured in isolated perfused hearts. Glyoxylic acid-induced histofluorescence was used to quantify cardiac sympathetic nerves. Compared with sham-operated animals (SH), AVS rats were characterized by depleted cardiac NE stores and enhanced NE plasma levels. Neither TH-mRNA levels in stellate ganglia, nor cardiac [3H]-NE-uptake were reduced in AVS. The left ventricular density of sympathetic nerves was markedly decreased. Gene expression of myocardial NGF (a positive regulator of NE reuptake and cardiac sympathetic nerve density) and left ventricular endothelin-1 (a negative regulator of NE reuptake and positive regulator of cardiac NGF expression) were unchanged. CONCLUSION: In volume-overloaded hypertrophic hearts, depletion of cardiac NE stores is caused by a reduction of the sympathetic nerve density, whereas cardiac NE reuptake is preserved.

Animals↗
PubMed2006

A comparison of measured trough levels and abbreviated AUC estimation by limited sampling strategies for monitoring mycophenolic acid exposure in stable heart transplant patients receiving cyclosporin A-containing and cyclosporin A-free immunosuppressive regimens.

BACKGROUND: Mycophenolate mofetil (NIMF) pharmacokinetics vary widely, and enterohepatic recirculation of the drug and its metabolites may be altered by concurrently administered immunosuppressants, including the widely used agent cyclosporin A (CsA). A reliable method of achieving effective and well-tolerated levels of NIMF-based immunosuppression would be of eminent interest. OBJECTIVE: This study compared the use of measured mycophenolic acid (MPA) trough levels (C0) and abbreviated AUC estimation by limited-sampling strategies for monitoring MPA exposure in stable heart transplant recipients (>1 year after transplantation) receiving a CsA-containing or CsA-free immunosuppressive regimen. METHODS: The treatment groups were receiving chronic maintenance immunosuppressive regimens consisting of either CsA/MMF or rapamycin (RAPA)/MMF. An additional subgroup of patients was switched from the CsA-containing regimen to the RAPA-containing regimen. Fasting venous blood samples were obtained before dosing and at 40, 75, 120, and 240 minutes after administration of the morning dose of MME The validated Emit assay was used to measure MPA plasma concentrations. Dose adjustment of AUCs was performed by dividing the AUC by the morning NIMF dose in grams. Cmax after administration of the morning dose was determined from available MPA data points using curve-fitting analysis. The increase to Cmax (Cmax-C0) was calculated, and dose adjustment was performed as before. Abbreviated 12-hour MPA AUCs were estimated using a limited-sampling strategy (before dosing and 30 and 120 minutes after dosing) based on high-performance liquid chromatography data. Adverse events were monitored during routine follow-up visits. RESULTS: The study included 47 patients receiving CsA/MMF, 15 receiving RAPA/MMF, and 9 who were switched from CsA/MMF to RAPA/MME The population included 55 men and 7 women, with a mean age of 58.94 years and a mean weight of 81.85 kg. The only significant differences in baseline clinical characteristics between groups were the mean number of years since heart transplantation (3.62 CsA/MMF vs 8.53 RAPA/MMF; P<0.01) and the proportions of patients still receiving corticosteroids (44.7% vs 13.3%, respectively; P<0.01). Reported adverse events were generally mild, including leukopenia (8.1%), diarrhea (6.5%), and abdominal pain (4.8%), and did not require drug discontinuation. In patients receiving CsA/MMF, MPA AUCs ranged from 19.67 to 81.80 mg/h.L (mean [SD], 41.92 [14.14] mg/h.L). MPA Co levels were poorly correlated with total AUC (r2=0.36). MPA Co levels of 0.5 and 1.6 mg/L were correlated with AUCs of <30 and <40 mg/h.L, respectively. In patients receiving RAPA/MMF, MPA AUCs ranged from 34.40 to 87.60 mg/h.L (mean, 51.07 [15.80] mg/h.L). The correlation between Co and total AUC was better than in the CsA/MMF group (r2=0.61). MPA C0 levels of 1.0 and 2.3 mg/L were correlated with AUCs of 30 and 40 mg/h.L, respectively. Statistically significant differences between RAPA/MMF and CsA/MMF were noted in the mean MMF dosage (1.90 [0.71] vs 2.87 [0.78] g/d, respectively; P<0.001), the mean dose-adjusted MPA AUC (60.95 [27.42] vs 31.92 [16.12] mg/h.L.g MMF; P<0.001), and mean dose-adjusted MPA C0 levels (5.10 [3.41] vs 1.41 [0.95] mg/L.g; P<0.001). The dose-adjusted increase to Cmax after morning dosing was comparable between groups, and there was no difference in the frequency distribution of Cmax. In the group switched from the CsA-containing regimen to the RAPA-containing regimen, the changes in MMF dose, dose-adjusted AUC, and MPA C0 levels were similar to those in the CsA/MMF and RAPA/MMF groups. CONCLUSIONS: In this comparison of measured MPA C0 levels and 12-hour MPA AUCs estimated by a limited-sampling strategy in stable heart transplant patients receiving chronic maintenance immunosuppressive therapy with CsA/MMF or RAPA/MMF, abbreviated AUC estimation predicted drug exposure more accurately than did measured C0 levels. Thus, MPA AUCs obtained by limited sampling may be useful in guiding clinical management and dosing. However, further study is required, including validation of these findings in clinical outcome studies.

Area Under Curve↗
PubMed2006

Ultrasound exposure can increase the membrane permeability of human neutrophil granulocytes containing microbubbles without causing complete cell destruction.

Activated polymorphonuclear neutrophil (PMN) granulocytes can bind and subsequently phagocytose microbubbles used as ultrasound (US) contrast agents. The purpose of the present study was to assess insonation effects on cell membrane integrity and metabolic activity of activated PMN. Furthermore, we investigated whether or not there is an acoustic threshold at which insonation of PMN results in increase of membrane permeability without causing complete cell destruction. PMN isolated from healthy volunteers were activated with phorbol myristate acetate (PMA) for 15 min to allow phagocytosis of albumin and lipid microbubbles and were subsequently exposed to US with a mechanical index between 0.15 and 1.8. Apoptosis, loss of membrane integrity and formation of cell fragments were evaluated by measurement of lactate dehydrogenase leakage and by double staining with annexin V and propidium iodide, using flow cytometry. Neutrophil superoxide anion generation was measured photometrically. Insonation of activated PMN in the presence of microbubbles amplified apoptosis and lactate dehydrogenase leakage and induced loss of membrane integrity and complete cell destruction with increasing acoustic pressures. The bioeffects observed by insonation with high mechanical indices (1.0 to 1.8), and particularly the formation of cell fragments, were significantly more pronounced in the presence of albumin microbubbles. Insonation in the presence of lipid microbubbles increased cell membrane permeability, but caused significantly less cell destruction and left the metabolic activity of activated PMN uninfluenced. Thus, both albumin and lipid microbubbles induce apoptosis and membrane injury during insonation of activated PMN. However, insonation in the presence of lipid microbubbles seems to influence cell viability to a smaller extent. This could be of advantage in the setting of US-guided local drug delivery. In this setting, increase of membrane permeability may allow bioactive substances to enter into cells, which survive the US treatment, and specifically modify their function.

Albumins↗
PubMed2006

The potential of a new stable ultrasound contrast agent for site-specific targeting. An in vitro experiment.

Microbubble-based ultrasound contrast agents can be used for specific site targeting, but demonstrate time-limited opacification. We have previously demonstrated the potential of gold-bound microtubules to provide a stable ultrasound contrast effect. Aim of the present study was to test the feasibility of gold-bound microtubules specifically to bind to human thrombi and to inflammatory activated human umbilical vein endothelial cells (HUVEC) in vitro. HUVEC were incubated with tumor necrosis factor, to induce expression of adhesion molecules. Human clots and HUVEC were incubated with biotinylated monoclonal antifibrin and anti-E-selectin antibodies, respectively. Probes were incubated with excess avidin followed by biotinylated gold-bound microtubules and by secondary Cy3-anti-beta-tubulin antibody and processed for immune fluorescence microscopy. Clots were transferred in copolymer foils filled with buffer and were ultrasonographically imaged before and after their treatment with the antifibrin antibody and with biotinylated microtubules, using a broadband harmonic transducer, transmitting and receiving at a mean frequency of 1.7 MHz and 3.2 MHz. The feasibility of specific gold-bound microtubules conjugation to antibody treated clots and HUVEC was confirmed using immune fluorescence analysis. Contrast intensities of the clots significantly increased after their treatment with antifibrin antibody and incubation with gold-bound microtubules (39 +/- 2 dB versus 26 +/- 2 dB, p < 0.001) and remained high after 20 min of ultrasound exposure (37 +/- 2 dB versus 39 +/- 2 dB, p = NS). Thus, gold-bound microtubules can specifically bind to human thrombi and to endothelial cells, providing a significant contrast effect which remains stable in the ultrasound field. This may be a promising approach to target thrombi and inflammatory active atherosclerotic plaques.

Antibodies, Monoclonal↗
PubMed2006

Identification of a 94-bp GC-rich element in the smooth muscle myosin heavy-chain promoter controlling vascular smooth muscle cell-specific gene expression.

The previously described rabbit 2.3-kilobase smooth muscle myosin heavy-chain (SMHCwt) promoter targets gene expression in transgenic animals to vascular smooth muscle cells (SMCs), including coronary arteries. Therefore, SMHCwt is thought to provide a promising tool for human gene therapy. In the present study, we examined tissue specificity and expression levels of wild-type and mutated SMHC promoters within the system of high-capacity adenoviral (hcAd) vectors. SMHCwt and a series of SMHC promoter deletion mutants, a triple promoter as well as a cytomegalovirus-SMHC hybrid promoter driving the enhanced green fluorescence protein (EGFP) reporter gene were transiently transfected into aortic SMCs. Fluorescence intensity was measured by flow cytometric analysis. Consecutively, hcAd vectors were constructed with the SMHCwt and the mutant promoter with the highest fluorescence activity. Levels of EGFP expression were determined after transduction of SMCs derived from human coronary arteries. For analysis of tissue specificity, embryonic stem (ES) cell-derived SMCs (ESdSMHCs) and cardiomyocytes (ESdCMs) were used. In comparison with SMHCwt, only the SMHCdel94 mutant lacking a 94-bp GC-rich element revealed a 1.5-fold increased fluorescence activity. Transduction of primary SMCs of human coronary arteries with hcAd vectors confirmed an increased EGFP expression driven by the SMHCdel94 promoter. In ES-cell-derived embryoid bodies, SMHCwt was exclusively active in transduced ESdSMCs. In contrast, expression of SMHCdel94 was also found in ESdCMs and other nontarget cells of the embryoid body. The tissue-specific rabbit SMHCwt promoter seems to be suitable for adenoviral gene transfer in SMCs of human coronary arteries and deletion of a 94-bp negative cis-acting GC-rich element results in loss of specificity.

Animals↗
PubMed2006

Multicentre evaluation of a new point-of-care test for the determination of NT-proBNP in whole blood.

BACKGROUND: The Roche CARDIAC proBNP point-of-care (POC) test is the first test intended for the quantitative determination of N-terminal pro-brain natriuretic peptide (NT-proBNP) in whole blood as an aid in the diagnosis of suspected congestive heart failure, in the monitoring of patients with compensated left-ventricular dysfunction and in the risk stratification of patients with acute coronary syndromes. METHODS: A multicentre evaluation was carried out to assess the analytical performance of the POC NT-proBNP test at seven different sites. RESULTS: The majority of all coefficients of variation (CVs) obtained for within-series imprecision using native blood samples was below 10% for both 52 samples measured ten times and for 674 samples measured in duplicate. Using quality control material, the majority of CV values for day-to-day imprecision were below 14% for the low control level and below 13% for the high control level. In method comparisons for four lots of the POC NT-proBNP test with the laboratory reference method (Elecsys proBNP), the slope ranged from 0.93 to 1.10 and the intercept ranged from 1.8 to 6.9. The bias found between venous and arterial blood with the POC NT-proBNP method was < or =5%. All four lots of the POC NT-proBNP test investigated showed excellent agreement, with mean differences of between -5% and +4%. No significant interference was observed with lipaemic blood (triglyceride concentrations up to 6.3 mmol/L), icteric blood (bilirubin concentrations up to 582 micromol/L), haemolytic blood (haemoglobin concentrations up to 62 mg/L), biotin (up to 10 mg/L), rheumatoid factor (up to 42 IU/mL), or with 50 out of 52 standard or cardiological drugs in therapeutic concentrations. With bisoprolol and BNP, somewhat higher bias in the low NT-proBNP concentration range (<175 ng/L) was found. Haematocrit values between 28% and 58% had no influence on the test result. Interference may be caused by human anti-mouse antibodies (HAMA) types 1 and 2. No significant influence on the results with POC NT-proBNP was found using volumes of 140-165 muL. High NT-proBNP concentrations above the measuring range of the POC NT-proBNP test did not lead to false low results due to a potential high-dose hook effect. CONCLUSIONS: The POC NT-proBNP test showed good analytical performance and excellent agreement with the laboratory method. The POC NT-proBNP assay is therefore suitable in the POC setting.

Calibration↗
PubMed2006

Posttranslationally modified proteins as mediators of sustained intestinal inflammation.

Oxidative and carbonyl stress leads to generation of N(epsilon)-carboxymethyllysine-modified proteins (CML-mps), which are known to bind the receptor for advanced glycation end products (RAGE) and induce nuclear factor (NF)-kappaB-dependent proinflammatory gene expression. To determine the impact of CML-mps in vivo, RAGE-dependent sustained NF-kappaB activation was studied in resection gut specimens from patients with inflammatory bowel disease. Inflamed gut biopsy tissue demonstrated a significant up-regulation of RAGE and increased NF-kappaB activation. Protein extracts from the inflamed zones, but not from noninflamed resection borders, caused perpetuated NF-kappaB activation in cultured endothelial cells, which was mediated by CML-mps including CML-modified S100 proteins. The resulting NF-kappaB activation, lasting 5 days, was primarily inhibited by either depletion of CML-mps or by the addition of sRAGE, p44/42 and p38 MAPKinase-specific inhibitors. Consistently, CML-mps isolated from inflamed gut areas and rectally applied into mice caused NF-kappaB activation, increased proinflammatory gene expression, and histologically detectable inflammation in wild-type mice, but not in RAGE-/- mice. A comparable up-regulation of NF-kappaB and inflammation on rectal application of CML-mps was observed in IL-10-/- mice. Thus, CML-mps generated in inflammatory lesions have the capacity to elicit a RAGE-dependent intestinal inflammatory response.

Adult↗
PubMed2005

Injection of nerve growth factor into stellate ganglia improves norepinephrine reuptake into failing hearts.

An impairment of cardiac norepinephrine reuptake through the neuronal norepinephrine transporter promotes depletion of cardiac norepinephrine stores and local cardiac sympathetic activation in heart failure. Nerve growth factor regulates differentiation and survival of adult sympathetic cells and is decreased in failing hearts. We hypothesized that injection of nerve growth factor into stellate ganglia normalizes cardiac norepinephrine homeostasis in experimental heart failure. Rats with transverse aortic constriction characterized by heart failure, depleted cardiac norepinephrine stores, and impaired cardiac norepinephrine reuptake were used as an experimental model. Nerve growth factor (20 microg) or saline was directly injected into left stellate ganglia 4 weeks after transverse aortic constriction. Thirty-two hours after injection, determinants of cardiac norepinephrine homeostasis were measured. As compared with saline, nerve growth factor refilled depleted cardiac norepinephrine stores and improved cardiac [3H]-norepinephrine uptake into isolated perfused hearts of transverse aortic constricted rats. In addition, pharmacological blockade of the norepinephrine transporter led to a higher increase in the overflow of endogenous norepinephrine from hearts of nerve growth factor-injected than saline-injected transverse aortic constricted rats. Norepinephrine transporter mRNA levels and the density of cardiac sympathetic nerves were not changed. Thirty-two hours after nerve growth factor injection, echocardiography revealed an increase in fractional shortening as compared with 2 days before injection. In conclusion, nerve growth factor attenuates local cardiac sympathetic overdrive of hypertrophic hearts by improving cardiac norepinephrine reuptake and might represent a novel therapeutic principle in the treatment of heart failure.

Animals↗
PubMed2005

Critical role for monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha in induction of experimental autoimmune myocarditis and effective anti-monocyte chemoattractant protein-1 gene therapy.

BACKGROUND: Autoimmune myocarditis is a principal cause of heart failure among young adults and is often a precursor of dilated cardiomyopathy. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) are potent chemotactic factors for mononuclear cells. The inflammatory infiltrate observed in myocardial lesions of myocarditis consists of >70% mononuclear cells. To determine their critical role in the pathogenesis of myocarditis, we inhibited mononuclear cell activation and migration to see if it would affect disease severity and disease prevalence in experimental autoimmune myocarditis (EAM). METHODS AND RESULTS: In this report, we demonstrated that blockade of MCP-1 or MIP-1alpha with monoclonal antibodies significantly reduced severity of myocarditis in BALB/c mice immunized with cardiac myosin. Similar results were obtained when CCR2-/- and CCR5-/- mice were used. In CCR2-/- mice, not only disease severity but also disease prevalence was reduced. To further inhibit mononuclear cell activation and migration, we transfected the mice before inducing EAM with a dominant-negative inhibitor of MCP-1 gene (7ND). This transfection significantly reduced the disease severity, decreased mRNA expression levels, especially of the chemokines RANTES, MIP-2, IP-10, MCP-1, T-cell activation gene 3, and eotaxin in the myocardium, and resulted in a reduction in cardiac myosin-induced interleukin-1 and interleukin-4 and in an increase in interferon-gamma and interleukin-10 cytokine production by splenocytes. CONCLUSIONS: Overall, these findings suggest that the chemokines MCP-1 and MIP-1alpha, acting through their receptors CCR2 and CCR5, are important in the induction of EAM and that inhibition of MCP-1 with 7ND gene transfection significantly reduced disease severity. This strategy may be a new feasible form of gene therapy against autoimmune myocarditis.

Animals↗
PubMed2005

Myocardial preconditioning and remote renal preconditioning--identifying a protective factor using proteomic methods?

It is still unknown whether remote ischemic preconditioning is mediated by a humoral or a neurogenic mechanism from the preconditioning to the preconditioned tissue. The purpose of the following study was to identify a possible humoral trigger of ischemic myocardial preconditioning and remote renal preconditioning. Open chest rats were subjected to a coronary artery occlusion period of 45 min followed by 2 h of reperfusion (Control animals; n = 6). The coronary preconditioned group (IPC, n = 6) was subjected to a preceding preconditioning period of 5 min coronary artery occlusion followed by 5 min of reperfusion, repeated three times. The renal preconditioned group (IPR, n = 6) was subjected to a preceding renal artery occlusion period of 10 min followed by 20 min of reperfusion. Area at risk (AAR) and infarcted area (IA) were determined at the end of each protocol. Blood samples were taken at the end of the preconditioning protocols from parallel experiments for proteomic analysis using two-dimensional gel electrophoresis (2-DE), matrix assisted laser desorption and ionization-time of flight-mass spectrometry (MALDI-TOF-MS), and liquid chromatography-electrospray ionization-tandem mass spectrometry (nanoLC-ESI-MS/MS). IA/AAR was 87.8 +/- 10.7% in the control group. IPC and IPR significantly reduced IA/AAR (58.2 +/- 9.3% and 56.9 +/- 9.0%, p < 0.001). Proteomic analyses detected four protein spots which were either up- (n = 3) or down-regulated in the preconditioned groups vs. the control group. The three up-regulated protein spots were identified as albumin fragments, whereas the down-regulated spot was identified as liver regeneration-related protein (LRRG03). Interestingly, albumin modification by brief ischemia has been recently shown and evaluated for the clinical diagnosis of sublethal myocardial ischemia. However, no differentially abundant proteins which possess a known signaling function could be found. Hence, though there is a differential protein expression in blood following IPC and IPR, our data are not in favor of a humoral mediator of remote preconditioning with a molecular weight of more than 8 kDa. Our results rather suggest either a neurogenic pathway or a mediator smaller than 8 kDa.

Albumins↗
PubMed2005

Metabolic control analysis of the Warburg-effect in proliferating vascular smooth muscle cells.

The accumulation and proliferation of vascular smooth muscle cells (VSMC) within the vessel wall is an important pathogenic feature in the development of atherosclerosis. Glucose metabolism has been implicated to play an important role in this cellular mechanism. To further elucidate the role of glucose metabolism in atherogenesis, glycolysis and its regulation have been investigated in proliferating VSMC. Platelet derived growth factor (PDGF BB)-induced proliferation of VSMCs significantly stimulated glucose flux through glycolysis. Further evaluating the enzymatic regulation of this pathway, the analysis of flux:metabolite co-responses revealed that anaerobic glycolytic flux is controlled at different sites of gycolysis in proliferating VSMCs, being consistent with the concept of multisite modulation. These findings indicate that regulation of glycolytic flux in proliferating VSMCs differs from traditional concepts of metabolic control of the Embden-Meyerhof pathway.

Becaplermin↗
PubMed2005

Regulation of cardiac inwardly rectifying potassium current IK1 and Kir2.x channels by endothelin-1.

To elucidate the ionic mechanism of endothelin-1 (ET-1)-induced focal ventricular tachyarrhythmias, the regulation of I(K1) and its main molecular correlates, Kir2.1, Kir2.2 and Kir2.3 channels, by ET-1 was investigated. Native I(K1) in human atrial cardiomyocytes was studied with whole-cell patch clamp. Human endothelin receptors were coexpressed with human Kir2.1, Kir2.2 and Kir2.3 channels in Xenopus oocytes. Currents were measured with a two-microelectrode voltage clamp. In human cardiomyocytes, ET-1 induced a marked inhibition of I(K1) that could be suppressed by the protein kinase C (PKC) inhibitor staurosporine. To investigate the molecular mechanisms underlying this regulation, we studied the coupling of ET(A) receptors to homomeric and heteromeric Kir2.1, Kir2.2 and Kir2.3 channels in the Xenopus oocyte expression system. ET(A) receptors coupled functionally to Kir2.2 and Kir2.3 channels but not to Kir2.1 channels. In Kir2.2 channels lacking functional PKC phosphorylation sites, the inhibitory effect was abolished. The inhibition of Kir2.3 currents could be suppressed by the PKC inhibitors staurosporine and chelerythrine. The coupling of ET(A) receptors to heteromeric Kir2.1/Kir2.2 and Kir2.2/Kir2.3 channels resulted in a strong inhibition of currents comparable with the effect observed in Kir2.2 homomers. Surprisingly, in heteromeric Kir2.1/Kir2.3 channels, no effect was observed. ET-1 inhibits human cardiac I(K1) current via a PKC-mediated phosphorylation of Kir2.2 channel subunits and additional regulatory effects on Kir2.3 channels. This mechanism may contribute to the intrinsic arrhythmogenic potential of ET-1.

Aged↗
PubMed2005

Risk stratification of chest pain patients by point-of-care cardiac troponin T and myoglobin measured in the emergency department.

A prospective multicenter study including 1410 chest pain patients with suspected acute coronary syndromes was carried out to examine the predictive value of biological cardiac markers for adverse events measured by a point-of-care system. Admission cardiac troponin T (cTnT) and myoglobin were measured in parallel on a point-of-care system in the emergency department and -- together with CK-MB mass -- on lab analyzers. In a one-year follow-up, cardiac and non-cardiac death, acute myocardial infarction, unstable angina pectoris and need for revascularization were registered. Median time between onset of symptoms and admission was 285 min; 172 patients (12.2%) had no event during follow-up. If the cTnT, measured either by the point-of-care system or a conventional lab analyzer, was >0.05 microg/L, then the chance of a cardiac event during the follow-up period was doubled (18% vs. 9%). Serial cTnT measurement did not add any further value to the predictive power of the admission cTnT. Myoglobin and CK-MB mass identified increasing risk with increasing concentration quartiles; cardiac event rates were 2.8- to 4.4-fold higher between the quartiles with the lowest and those with the highest analyte concentration, respectively. There was no difference in non-cardiac death rates between any concentration quartiles. In conclusion, the prediction of clinical events by cardiac troponin T and myoglobin measured with a point-of-care analyzer in the emergency department was as good as that of the same cardiac markers and CK-MB mass measured on lab analyzers.

Aged↗