Meike Coldewey

Heme Oxygenase-1. A Novel Key Player in the Development of Tolerance in Response to Organic Nitrates

Objective—Nitrate tolerance is likely attributable to an increased production of reactive oxygen species (ROS) leading to an inhibition of the mitochondrial aldehyde dehydrogenase (ALDH-2), representing the nitroglycerin (GTN) and pentaerythrityl tetranitrate (PETN) bioactivating enzyme, and to impaired nitric oxide bioactivity and signaling. We tested whether differences in their capacity to induce heme oxygenase-1 (HO-1) might explain why PETN and not GTN therapy is devoid of nitrate and cross-tolerance. Methods and Results—Wistar rats were treated with PETN or GTN (10.5 or 6.6 μg/kg/min for 4 days). In contrast to GTN, PETN did not induce nitrate tolerance or cross-tolerance as assessed by isometric tension recordings in isolated aortic rings. Vascular protein and mRNA expression of HO-1 and ferritin were increased in response to PETN but not GTN. In contrast to GTN therapy, NO signaling, ROS formation, and the activity of ALDH-2 (as assessed by an high-performance liquid chromatography–based method) were not significantly influenced by PETN. Inhibition of HO-1 expression by apigenin induced “tolerance” to PETN whereas HO-1 gene induction by hemin prevented tolerance in GTN treated rats. Conclusions—HO-1 expression and activity appear to play a key role in the development of nitrate tolerance and might represent an intrinsic antioxidative mechanism of therapeutic interest.

NADPH Oxidase Accounts for Enhanced Superoxide Production and Impaired Endothelium-Dependent Smooth Muscle Relaxation in BKβ1−/− Mice

Objective—Nitric oxide (NO)-induced vasorelaxation involves activation of large conductance Ca2+-activated K+ channels (BK). A regulatory BK&bgr;1 subunit confers Ca2+, voltage, and NO/cGMP sensitivity to the BK channel. We investigated whether endothelial function and NO/cGMP signaling is affected by a deletion of the &bgr;1-subunit. Methods and Results—Vascular superoxide in BK&bgr;1−/− was measured using the fluorescent dye hydroethidine and lucigenin-enhanced chemiluminescence. Vascular NO formation was analyzed using electron paramagnetic resonance (EPR), expression of NADPH oxidase subunits, the endothelial NO synthase (eNOS), the soluble guanylyl cyclase (sGC), as well as the activity and expression of the cyclic GMP-dependent kinase I (cGK-I) were assessed by Western blotting technique. eNOS, sGC, cGK-I expression and acetylcholine-induced NO production were unaltered in Bk&bgr;1−/− animals, whereas endothelial function was impaired and the activity of the cGK-I was reduced. Vascular O2− and expression of the NADPH oxidase subunits p67phox and Nox1 were increased. Endothelial dysfunction was normalized by the NADPH oxidase inhibitor apocynin. Potassium chloride- and iberiotoxin-induced depolarization mimicked the effect of BK&bgr;1-deletion by increasing vascular O2− in an NADPH-dependent fashion. Conclusions—The deletion of BK&bgr;1 causes endothelial dysfunction by increasing O2− formation via increasing activity and expression of the vascular NADPH oxidase.

Hyperglycemia and oxidative stress in cultured endothelial cells - a comparison of primary endothelial cells with an immortalized endothelial cell line

Diabetes mellitus is a major risk factor for the development of cardiovascular disease and oxidative stress plays an important role in this process. Therefore, we investigated the effects of hyperglycemia on the formation of reactive oxygen species (ROS) and nitric oxide/cGMP signaling in two different endothelial cell cultures. Human umbilical vein endothelial cells (HUVEC) and EA.hy 926 cells showed increased oxidative stress and impaired NO-cGMP signaling in response to hyperglycemia. The major difference between the two different cell types was the dramatic decrease in viability in HUVEC whereas EA.hy cells showed rather increased growth under hyperglycemic conditions. Starvation led to an additional substantial decrease in viability and increased superoxide formation in HUVEC. Both endothelial cell types, HUVEC and EA.hy 926, may be used as models for vascular hyperglycemia. However, high growth medium should be used to avoid starvation-induced oxidative stress and cell death.

Quality of oral anticoagulation with phenprocoumon in regular medical care and its potential for improvement in a telemedicine-based coagulation service – results from the prospective, multi-center, observational cohort study thrombEVAL

BackgroundThe majority of studies on quality of oral anticoagulation (OAC) therapy with vitamin K-antagonists are performed with short-acting warfarin. Data on long-acting phenprocoumon, which is frequently used in Europe for OAC therapy and is considered to enable more stable therapy adjustment, are scarce. In this study, we aimed to assess quality of OAC therapy with phenprocoumon in regular medical care and to evaluate its potential for optimization in a telemedicine-based coagulation service.MethodsIn the prospective observational cohort study program thrombEVAL we investigated 2,011 patients from regular medical care in a multi-center cohort study and 760 patients from a telemedicine-based coagulation service in a single-center cohort study. Data were obtained from self-reported data, computer-assisted personal interviews, and laboratory measurements according to standard operating procedures with detailed quality control. Time in therapeutic range (TTR) was calculated by linear interpolation method to assess quality of OAC therapy. Study monitoring was carried out by an independent institution.ResultsOverall, 15,377 treatment years and 48,955 international normalized ratio (INR) measurements were analyzed. Quality of anticoagulation, as measured by median TTR, was 66.3% (inte rquartile range (IQR) 47.8/81.9) in regular medical care and 75.5% (IQR 64.2/84.4) in the coagulation service (P <0.001). Stable anticoagulation control within therapeutic range was achieved in 63.8% of patients in regular medical care with TTR at 72.1% (IQR 58.3/84.7) as compared to 96.4% of patients in the coagulation service with TTR at 76.2% [(IQR 65.6/84.7); Pu2009=u20090.001)]. Prospective follow-up of coagulation service patients with pretreatment in regular medical care showed an improvement of the TTR from 66.2% (IQR 49.0/83.6) to 74.5% (IQR 62.9/84.2; P <0.0001) in the coagulation service. Treatment in the coagulation service contributed to an optimization of the profile of time outside therapeutic range, a 2.2-fold increase of stabile INR adjustment and a significant decrease in TTR variability by 36% (P <0.001).ConclusionsQuality of anticoagulation with phenprocoumon was comparably high in this real-world sample of regular medical care. Treatment in a telemedicine-based coagulation service substantially improved quality of OAC therapy with regard to TTR level, frequency of stable anticoagulation control, and TTR variability.Trial registrationClinicalTrials.gov, unique identifier NCT01809015, March 8, 2013.

Heart rate in pulmonary embolism

Heart rate is a rapidly available risk stratification parameter in acute pulmonary embolism (PE). We aimed to investigate the effectiveness of heart rate in predicting the outcome in acute PE. Data of 182 patients with acute PE were analysed retrospectively. Logistic regression models were calculated to investigate the associations between heart rate and in-hospital death, myocardial necrosis, PE status and presence of right ventricular dysfunction (RVD), respectively. ROC curve and cut-off values for heart rate predicting RVD as well as intermediate risk PE status in normotensive PE patients and for heart rate predicting in-hospital death and myocardial necrosis in all PE patients were calculated. ROC analysis for heart rate predicting RVD and intermediate risk PE were 0.706 and 0.718, respectively, with cut-off value of 86xa0beats/min. Regression models showed associations between heart rate >85xa0beats/min and both RVD (OR 4.871, 95xa0% CI 2.256–10.515, Pxa0=xa00.000055) and intermediate risk PE (OR 5.244, 95xa0% CI 2.418–11.377, Pxa0=xa00.000027). In hemodynamically stable and unstable PE patients, logistic regression models showed a borderline significant association between tachycardia and in-hospital death (OR 7.066, 95xa0% CI 0.764–65.292, Pxa0=xa00.0849) and a significant association between heart rate and myocardial necrosis (OR 0.975, 95xa0% CI 0.959–0.991, Pxa0=xa00.00203). ROC analysis for heart rate predicting in-hospital death and myocardial necrosis revealed AUC of 0.655 and 0.703 with heart rate cut-off values of 99.5xa0beats/min and 92.5xa0beats/min, respectively. An elevated heart rate in acute PE is connected with a worse outcome. Effectiveness in the prediction of RVD, intermediate PE status, cardiac injury and in-hospital death is acceptable. The cut-off value for the prediction of RVD and intermediate risk PE status in normotensive PE is 86xa0beats/min, while tachycardia predicts in-hospital death.

Right ventricular dysfunction in hemodynamically stable patients with acute pulmonary embolism

BACKGROUNDnEchocardiography for risk stratification in hemodynamically stable patients with pulmonary embolism (PE) is well-established. Right ventricular dysfunction (RVD) is associated with an elevated mortality and adverse outcome. The aim of our study was to compare RVD criteria and investigate the role of elevated systolic pulmonary artery pressure (sPAP) in the diagnosis of RVD.nnnMETHODSnWe retrospectively analyzed the echocardiographic and laboratory data of all hemodynamically stable patients with confirmed PE (2006-2011). The data were compared with three different definitions of RVD: Definition 1: RV dilatation, abnormal motion of interventricular septum, RV hypokinesis or tricuspid regurgitation. Definition 2: as with definition 1 but including elevated sPAP (>30mmHg). Definition 3: elevated sPAP (>30mmHg) as single RVD criterion.nnnRESULTSnA total number of 129 patients (59.7% women, age 70.0years (60.7/81.0)) were included in this study. Median Troponin I level was measured as 0.02ng/ml (0/0.14); mean sPAP 33.9±18.5mmHg. The troponin cut-off levels for predicting a RVD of the 3 RVD definitions were in definition 1-3: >0.01ng/ml, >0.01ng/ml and >0.00ng/ml. Analysis of the ROC curve showed an AUC for RVD definitions 1-3: 0.790, 0.796 and 0.635.nnnCONCLUSIONSnThe combination of commonly used RVD criteria with added elevated sPAP improves the diagnosis of RVD in acute PE. Troponin I values of >0.01ng/ml in acute PE point to an RVD.

Impact of advanced age on the severity of normotensive pulmonary embolism

The prevalence of pulmonary embolism (PE) increases progressively with age. Less data about the impact of increasing age on the severity of PE are available. The objectives of this study were to investigate the impact of increasing age on the severity of normotensive PE. Retrospective analysis of clinical, laboratory, radiological and echocardiagraphic data of normotensive patients with PE was performed. According to patients’ age at the moment of acute PE event, the total number of 129 normotensive PE patients was subdivided into 4 age groups. In age groups 18–59, 60–69, 70–79 and 80–94xa0years were, respectively, a number of 30, 31, 33 and 35 patients included. Percentage of women in age groups increased with advanced age (Pxa0=xa00.021). Systolic pulmonary artery pressure (PAP) (Pxa0<xa00.0001) and frequency of incomplete or complete right bundle-branch block (RBBB) (Pxa0=xa00.019), of right ventricular dysfunction (RVD) (Pxa0=xa00.00031) and of submassive PE stadium with intermediate risk (Pxa0=xa00.0016) increased significantly with growing age. Multivariable regression model confirmed an association between age and submassive PE [OR (per year) 1.04; 95xa0% CI, 1.02–1.07, Pxa0=xa00.0020] as well as female gender and submassive PE (OR 2.45; 95xa0% CI, 1.10–5.50, Pxa0=xa00.029) and tachycardia and submassive PE (OR 15.33; 95xa0% CI, 3.45–68.24, Pxa0=xa00.00034). Advanced age, female gender and tachycardia are risk factors for a submassive PE with intermediate risk in normotensive PE patients. The percentage of PE patients with submassive PE, right ventricular overload, RVD, RBBB, elevated systolic PAP increases with advanced age.

Evaluation of oral anticoagulation therapy: rationale and design of the thrombEVAL study programme.

Background Since decades, oral anticoagulation (OAC) with vitamin K antagonists (VKA) is an established therapy for both prevention and treatment of thromboembolism in daily clinical routine. Increasing life expectancy, demographic changes, and novel oral anticoagulants have led to an increasing complexity of medical therapy. However, data on quality and management of VKA therapy with phenprocoumon in current medical care are limited. Our aim is to investigate the quality of OAC with VKA in current health care and to evaluate the potential for improvements. Study design The investigator-initiated thrombEVAL study programme comprises two cohorts of patients treated with vitamin K antagonists for oral anticoagulation therapy in real-life settings: a multicentre cohort of patients in regular medical care and a multilocal, single-centre cohort of patients in a telemedicine-based coagulation service. The study programme is expected to enrol a total number of approximately 2000 to 2500 patients. Both cohorts will build on a detailed clinical assessment of participants and anticoagulation therapy at study enrolment. Subsequently active and passive follow-up investigations are carried out to document and validate complications of the treatment. The primary short-term outcome is the distribution of time in therapeutic range; the primary long-term outcome comprises the composite of stroke, systemic embolism, myocardial infarction, major and clinically relevant bleeding, and death. Conclusions The thrombEVAL project will provide a large prospective observational cohort of patients predominantly treated with phenprocoumon. It will evaluate the quality of oral anticoagulation in regular medical care and a telemedicine-based coagulation service.

The risk factor age in normotensive patients with pulmonary embolism: Effectiveness of age in predicting submassive pulmonary embolism, cardiac injury, right ventricular dysfunction and elevated systolic pulmonary artery pressure in normotensive pulmonary embolism patients.

INTRODUCTIONnRight ventricular dysfunction (RVD), submassive pulmonary embolism (PE), elevated systolic pulmonary artery pressure (sPAP), elevated cardiac troponin I (cTnI) and old age are well-known risk factors for poor outcome in acute normotensive PE. The aim of this analysis was to calculate age cut-off values to predict submassive PE, cardiac injury, RVD and elevated sPAP in normotensive PE patients.nnnMETHODSnRetrospective analysis of clinical, laboratory, radiological and echocardiographic data of normotensive PE patients (2006-2011) was performed. Receiver operating characteristic (ROC) curves and Youden indexes were used to test the effectiveness of using patients ages at the PE event to predict a submassive PE, cardiac injury (elevated cTnI >0.1ng/ml), RVD and elevated sPAP (>30mmHg) in normotensive PE patients and to calculate optimal cut-off values. Patients >76years were compared to those aged ≤76years.nnnRESULTSn129 normotensive PE patients (59.7% women) met the inclusion criteria and were included in this analysis. The optimal cut-off value for patient ages to predict submassive PE, cardiac injury (elevated cTnI >0.1ng/ml), RVD and elevated sPAP (>30mmHg) was 76.5, 81.5, 66.5 and 66.5years, respectively, with moderate effectiveness (AUC 0.69, 0.58, 0.71 and 0.69, respectively). Patients >76years old had higher percentages of submassive PE (91.1% vs. 63.1%, P=0.000680), RVD (91.1% vs. 58.3%, P=0.000119), sPAP (42.64±16.70 vs. 29.24±17.56mmHg, P=0.000044) and cTnI (0.22±0.40 vs. 0.10±0.25ng/ml, P=0.00488).nnnCONCLUSIONSnAge is an important prognostic factor in acute normotensive PE. In addition to cTn and RVD, age should be taken into account in determining the risk stratification for acute PE.

D-dimer for risk stratification in haemodynamically stable patients with acute pulmonary embolism

PURPOSEnPatients with submassive pulmonary embolism (PE) have a higher short-term mortality than those with low-risk PE. Rapid identification of submassive PE is important for adequate treatment of non-massive PE. We aimed to investigate the utility of D-dimer for the prediction of submassive PE stadium in normotensive PE patients.nnnPATIENTS AND METHODSnNormotensive PE patients were classified into submassive or low-risk PE groups. In addition to the comparison of the groups, area under the curve (AUC) and D-dimer cut-off for the prediction of submassive PE stadium, multi-variate logistic regression for association between D-dimer values above this cut-off and submassive PE stadium were also calculated.nnnRESULTSnThe data of 129 normotensive PE patients (59.7% women, mean age 70.0 years (60.7/81.0)) were analysed retrospectively. Patients with submassive PE were older (75.0 years (61.7/81.0) vs. 66.5 years (55.7/74.2), P=0.026) and more frequently female (63.6% vs. 53.8%, P=0.35). Heart rate (100.0beats/min (85.0/108.0) vs. 80.0beats/min (70.0/96.2), P<0.0001), systolic pulmonary-artery pressure (41.55±16.79mmHg vs. 22.62±14.81mmHg, P<0.0001), and D-dimer (2.00mg/l (1.09/3.98) vs. 1.21mg/l (0.75/1.99), P=0.011) were higher in patients with submassive PE. D-dimer values >1.32mg/l were indicative of submassive PE and shock-index ≥0.7. The effectiveness (AUC) of the test was 0.63 for submassive PE and 0.64 for shock-index ≥0.7. D-dimer values >1.32mg/l were associated with submassive PE stadium (OR 3.81 (95% CI: 1.74-8.35), P=0.00083) as well as with systolic blood pressure (OR 0.98 (95% CI: 0.97-0.99), P=0.033), heart rate (OR 1.02 (95% CI: 1.00-1.04), P=0.023) and shock-index value (OR 15.89 (95% CI: 1.94-130.08), P=0.0099).nnnCONCLUSIONSnD-dimer values >1.32mg/l are indicative of submassive PE stadium and shock-index ≥0.7. Efficacy of D-dimer for predicting submassive PE stadium was only weak to moderate.