Association of aortic stiffness with biomarkers of myocardial wall stress after myocardial infarction.

BACKGROUND: Aortic pulse wave velocity (PWV) was linked to LV-geometry and -function in patients with kidney disease and non-ischemic cardiomyopathy. The role of aortic compliance after acute STEMI is so far unknown. In the present study, we prospectively investigated the relationship of increased aortic stiffness with biomarkers of myocardial wall stress 4 months after STEMI. METHODS: 48 STEMI patients who were reperfused by primary coronary angioplasty underwent cardiovascular magnetic resonance (CMR) at baseline and at 4-month follow-up. The CMR protocol comprised cine-CMR as well as gadolinium contrast-enhanced CMR. Aortic PWV was determined by velocity-encoded, phase-contrast CMR. Blood samples were routinely drawn at baseline and follow-up to determine N-terminal pro-B-type natriuretic peptide (NT-proBNP). In a subgroup of patients, mid-regional pro-adrenomedullin (MR-proADM) and mid-regional pro-A-type natriuretic peptide (MR-proANP) levels were determined. RESULTS: Patients with a PWV above median (>7.0m/s) had significantly higher NT-proBNP, MR-proADM and MR-proANP concentrations at 4-month follow-up than patients with a PWV below median (all p<0.02). PWV showed moderate to good correlation with NT-proBNP, MR-proAMD and MR-proANP levels 4 months after STEMI (all p<0.05). Multivariate analysis revealed PWV, beside myocardial infarct size, as an independent predictor of 4-month NT-proBNP levels after correction for age, creatinine and LV ejection fraction (model r: 0.781, p<0.001). CONCLUSION: Aortic stiffness is directly associated with biomarkers of myocardial wall stress 4 months after reperfused STEMI, suggesting a role for aortic stiffness in chronic LV-remodelling.

Antimicrobial and anticoagulant activities of N-chlorotaurine, N,N-dichloro-2,2-dimethyltaurine, and N-monochloro-2,2-dimethyltaurine in human blood.

The aim of this study was to determine the potential application of N-chlorotaurine (NCT), N,N-dichloro-2,2-dimethyltaurine (NVC-422), and N-monochloro-2,2-dimethyltaurine (NVC-612) as catheter lock solutions for the prevention of catheter blockage and catheter-related bloodstream infections by testing their anticoagulant and broad-spectrum antimicrobial activities in human blood. NCT, NVC-422, NVC-612, and control compounds were serially diluted in fresh human blood to evaluate the effects on prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, and direct thrombin inhibition. Quantitative killing assays against pathogens, including methicillin-resistant Staphylococcus aureus, Escherichia coli, and Candida albicans, were performed in the presence of heparin and human blood. NCT and NVC-612 (1.38 mM each) and 1.02 mM NVC-422 prolonged prothrombin time (Quick value, 17 to 30%), activated partial thromboplastin time 3- to 4-fold to 76 to 125 s, and thrombin time 2- to 4-fold to 34 to 68 s. Fibrinogen decreased from 258 to 283 mg/dl (range of controls) to <40 mg/dl. No direct thrombin inhibition was observed by NVC-422 or NVC-612. Heparin did not influence the bactericidal activity of NCT. The microbicidal activities of NCT, NVC-422, and NVC-612 were maintained in diluted human blood. NCT, NVC-612, and NVC-422 have broad-spectrum antimicrobial activity in blood and anticoagulant activity targeting both intrinsic and extrinsic pathways of the coagulation system. These properties support their application as catheter lock solutions.

The impact of cardiac natriuretic peptide determination on the diagnosis and management of heart failure.

The long-predicted endocrine function of the heart has been proven by the discovery of atrial natriuretic peptide (atrial natriuretic factor, A-type natriuretic peptide; ANP) 20 years ago. This subsequently led to the description of a whole family of structurally similar but genetically distinct peptides, the natriuretic peptide family, which contributes to cardiovascular homeostasis. These looped peptides promote natriuresis and diuresis, act as vasodilators, and exert antimitogenic effects on cardiovascular tissues. Two members, ANP and brain natriuretic peptide (B-type natriuretic peptide; BNP) are secreted by the heart mainly in response to myocardial stretch induced by volume load. The natriuretic peptides are synthesized as preprohormones. The C-terminal endocrinological active peptides (ANP, BNP) and their N-terminal prohormone fragments are found in plasma. The natriuretic peptide system is activated to its highest degree in ventricular dysfunction. However, natriuretic peptides are increased in all patients with edematous disorders which lead to an increase in atrial tension or central blood volume, such as renal failure or ascitic liver cirrhosis. It could be demonstrated that in chronic heart failure patients and during the subacute phase of myocardial infarction, of all tested neurohormones, the cardiac natriuretic peptides were best markers to identify heart failure and the most powerful predictors of morbidity and mortality. Natriuretic peptides are independent markers for risk assessment. In comparative studies BNP was superior to ANP and its N-terminal prohormone fragments in myocardial infarction as well as in chronic heart failure patients. Less data on N-terminal proBNP (NT-proBNP) is available, but BNP and NT-proBNP appear to be equivalent markers. For primary care physicians natriuretic peptide measurement is useful to decide which patient with suspected heart failure warrants further investigation, particularly when assessment of left ventricular function is not readily available. Natriuretic peptides have an excellent negative predictive value, particularly in high risk patients. An increase in BNP is serious enough to warrant follow-up examinations. For the cardiologists the natriuretic peptides are helpful for guidance of therapy and monitoring disease course in heart failure patients and for risk stratification in heart failure and myocardial infarction.

Head-to-head comparison of N-terminal pro-brain natriuretic peptide, brain natriuretic peptide and N-terminal pro-atrial natriuretic peptide in diagnosing left ventricular dysfunction.

Brain natriuretic peptide (BNP), NT-proBNP and NT-pro-atrial natriuretic peptide (NT-proANP) were measured in blood samples from 57 patients using immunoassays and immunoradiometric assays to evaluate the usefulness as diagnostic markers for the detection of heart failure. For the detection of impaired left ventricular ejection fraction (LVEF), receiver operating characteristic curves showed that BNP had the best diagnostic performance with an area under curve (AUC) of 0.75+/-0.06. However, NT-proBNP (AUC: 0.67+/-0.07) and NT-proANP (AUC: 0.69+/-0.08) showed no significant difference to BNP. In a further analysis for the detection of resting LVEF <40%, BNP again was the best marker with an AUC of 0.83+/-0.06. NT-proBNP showed only a slightly smaller AUC (0.79+/-0.07). The AUC for NT-proANP was significantly smaller (0.65+/-0.08) compared to BNP. Additionally, BNP and NT-proBNP correlated negatively with the resting LVEF (BNP: -0.472, p<0.001; NT-proBNP: -0.306, p=0.026), whereas NT-proANP showed no significant correlation. In summary, BNP was the best marker to detect patients with impaired LVEF compared to NT-proBNP and NT-proANP. However, NT-proBNP showed no significant differences to BNP and it is therefore a new promising alternative marker for the detection of left ventricular dysfunction.

Cardiac natriuretic peptides: new laboratory parameters in heart failure patients.

Natriuretic peptides, atrial natriuretic peptide and brain natriuretic peptide, are key regulators in the homeostasis of salt and water excretion and in the maintenance of blood pressure. During heart failure, these peptides are highly activated because of volume overload and increased myocardial wall tension. Among all natriuretic peptides and neurohormones, brain natriuretic peptide and its N-terminal prohormone fragment have been shown to be the best markers to identify patients with heart failure. They are useful prognostic markers as well. The stability of brain natriuretic peptides and N-terminal prohormones in ethylene-diamine-tetraacetic-acid whole blood is sufficient for routine use. Sensitive and specific assays without the need for plasma extraction are commercially available. The available data indicate that natriuretic peptides are powerful diagnostic and prognostic markers in heart failure patients. First data on treatment guidance are promising.

Hypoxia induces heat shock protein expression in human coronary artery bypass grafts.

OBJECTIVE: Heat shock proteins (HSPs) are molecular chaperones which are essential for cell survival. Heat shock and hypoxia markedly increase the expression of several HSPs in various tissues, i.e. heart. In our in vitro study, we investigated whether HSPs are inducible in human vessels which are used as coronary artery bypass grafts. METHODS: We used remnants of the saphenous vein and the internal mammary artery from 34 patients undergoing coronary artery bypass surgery. Each vessel was divided into segments, one for control conditions at 37 degrees C (5% CO(2)-95% air), the remaining ones for thermal (30 min at 42 degrees C) or hypoxic treatment (6 h oxygen deprivation with nitrogen). The expression of Hsp60, Hsp72 and Hsp73 was investigated by immunohistochemistry and Western-blot analysis. RESULTS: Compared to controls, segments of the saphenous vein undergoing heat treatment showed significantly increased expression of Hsp72 in the intima (P=0.035) and Hsp73 in the media (P=0.003). In the internal mammary artery, Hsp72 and Hsp73 were expressed in the intima at significantly higher levels (P=0.042 each). A 6 h oxygen deprivation with nitrogen resulted in elevated levels of Hsp60 (media: P=0.048), of Hsp72 (intima: P<0.001 and media: P=0.004) and of Hsp73 (intima: P=0.029) in the saphenous vein. In the internal mammary artery, Hsp73 expression was significantly enhanced (intima: P=0.048 and media: P=0.017). The results were confirmed by Western-blot analysis in representative veins. CONCLUSIONS: These findings demonstrate the common cellular defense mechanism of HSP expression in response to stress in coronary artery bypass grafts. Hypoxia and heat treatment strongly induce Hsp72 and Hsp73 expression in human coronary artery bypass grafts.

Clinical and experimental results on cardiac troponin expression in Duchenne muscular dystrophy.

BACKGROUND: Because of controversial earlier studies, the purpose of this study was to provide novel experimental and additional clinical data regarding the possible reexpression of cardiac troponin T (cTnT) in regenerating skeletal muscle in Duchenne muscular dystrophy (DMD). METHODS: Plasma from 14 patients (mean age, 7.5 years; range, 5.7-19.4 years) with DMD was investigated for creatine kinase (CK), the CK MB isoenzyme (CKMB), cTnT and cardiac troponin I (cTnI), and myoglobin. cTnT concentrations were measured by an ELISA (second-generation assay; Roche) using the ES 300 Analyzer. cTnI, myoglobin, and CKMB were measured by an ELISA using the ACCESS System (Beckman Diagnostics). Troponin isoform expression was studied by Western blot analysis in remnants of skeletal muscle biopsies of three patients with DMD and in an animal model of DMD (mdx mice; n = 6). RESULTS: There was no relation of cTnT and cTnI to clinical evidence for cardiac failure. cTnI concentrations remained below the upper reference limit in all patients. cTnT was increased (median, 0.11 microg/L; range, 0.06-0.16 microg/L) in 50% of patients. The only significant correlation was found for CK (median, 3938 U/L; range, 2763-5030 U/L) with age (median, 7.5 years; range, 6.8-10.9 years; r = -0.762; P = 0.042). Western blot analysis of human or mouse homogenized muscle specimens showed no evidence for cardiac TnT and cTnI expression, despite strong signals for skeletal muscle troponin isoforms. CONCLUSIONS: We found no evidence for cTnT reexpression in human early-stage DMD and in mdx mouse skeletal muscle biopsies. Discrepancies of cTnT and cTnI in plasma samples of DMD patients were found, but neither cTnT nor cTnI plasma concentrations were related with other clinical evidence for cardiac involvement.