In experimental animals and in patients with pulmonary arterial hypertension (PAH), a wide spectrum of structural and functional conditions is known that may be responsible for the switch of a... Show moreIn experimental animals and in patients with pulmonary arterial hypertension (PAH), a wide spectrum of structural and functional conditions is known that may be responsible for the switch of a state of "compensated" right ventricular (RV) hypertrophy to a state of RV failure. In recent years, therapy with differentiated cells, endothelial progenitor cells, and mesenchymal stem cells has been shown to cause partial or complete reversal of pathological characteristics of PAH. The therapeutic effects of stem or progenitor cell therapy are considered to be (1) paracrine effects from stem or progenitor cells that had engrafted in the myocardium (or elsewhere), by compounds that have anti-inflammatory, antiapoptotic, and proangiogenic actions and (2) unloading effects on the right ventricle due to stem or progenitor cell-induced decrease in pulmonary vascular resistance and decrease in pulmonary artery pressure. Show less
Broek, I. van den; Romijn, F.P.H.T.M.; Smit, N.P.M.; Laarse, A. van der; Drijfhout, J.W.; Burgt, Y.E.M. van der; Cobbaert, C.M. 2015
In this study, we have followed up on previous liquid chromatography (LC) multiple reaction monitoring (MRM) mass spectrometry (MS) approaches for measurement of apolipoprotein (apo) A-I and apo... Show moreIn this study, we have followed up on previous liquid chromatography (LC) multiple reaction monitoring (MRM) mass spectrometry (MS) approaches for measurement of apolipoprotein (apo) A-I and apo B100 in serum aiming for implementation of a multiplexed assay in a clinical chemistry laboratory with full metrological traceability. Signature peptides were selected and detected by dynamic MRM, and stable isotope labeled (SIL)-peptides were used as internal standards. Five apo A-I and four apo B100 peptides were measured in serum digests with linearity (R(2)>0.992) in the physiologically relevant concentration ranges. Linearity with regard to protein concentration was ascertained at five concentration levels (R(2)>0.926 and R(2)>0.965, for the apo A-I and apo B100 peptides, respectively). Three native value-assigned sera were used as external calibrators for further method verification. Imprecision values on sample preparation and LC-MS/MS acquisition were below the established minimal specifications for apo A-I and apo B100 (5.0% and 5.3%, respectively). Correlation of LC-MS/MS results with immunoturbidimetric assay results, for normo- and hypertriglyceridemic samples, showed R(2)>0.944 for apo A-I and R(2)>0.964 for apo B100. This LC-MS/MS method has potential for clinical application in normo- and dyslipidemic patients.\nBIOLOGICAL SIGNIFICANCE\nMeasurement of apo A-I and apo B100 may offer an alternative to high and low density lipoprotein cholesterol (HDL-c and LDL-c) methods for cardiovascular disease risk assessment in dyslipidemic patients [1]. An LC-MS/MS method for apo A-I and apo B100 has the advantage of antibody independent and specific detection of protein signature peptides. The introduction of an LC-MS/MS method for apo A-I and apo B100 can serve as an example for many existing and newly developed (multiplex) biomarker methods in quantitative clinical chemistry proteomics (qCCP). Such LC-MS/MS methods should meet basic clinical chemistry principles with regard to test evaluation [2]. Criteria for imprecision should be pre-defined, e.g., based on biological variation. The use of commutable and traceable serum-based calibrators will improve inter-laboratory reproducibility of LC-MS/MS methods and may contribute to a more rapid transition of biomarker discovery to clinical utility with benefit for the patient treatment and improvement of general health care. Show less
Buiten, M.; Rotmans, J.; Laarse, A. van der; Jukema, J. 2014
To improve patient outcome, point-of-care (POC) cardiac troponin I/T (cTn I/T) tests applied in a prehospital setting and/or emergency department might play a role as a substitute for central... Show moreTo improve patient outcome, point-of-care (POC) cardiac troponin I/T (cTn I/T) tests applied in a prehospital setting and/or emergency department might play a role as a substitute for central hospital laboratory high-sensitivity (hs) cTn I/T testing if their analytical and clinical performance are equivalent to central hospital laboratory hs cTn I/T tests and if they fulfill an unmet clinical need in the diagnostic work-up of patients with acute coronary syndrome (ACS). To date, current point-of-care (POC) cTn I/T tests are not yet sufficiently analytically sensitive and do not provide accurate and precise values in the reference range nor at the 99th percentile of a healthy reference population. Awaiting the development of improved hs POC cTn I/T tests, current POC cTn I/T tests should be combined with ECG as it takes several hours to detect a rise of cTn I/T in the circulation whereas ischemia-induced ECG changes may be observed soon after onset of chest pain. Although patients with acute ST-segment elevation myocardial infarction (STEMI) are generally diagnosed by ischemic symptoms and ECG only, hospitalized patients with non-STEMI and unstable angina pectoris (UAP) should preferentially be tested with ECG and central hospital laboratory hs cTn I/T tests unless the ECG has already demonstrated diagnostic changes. More evidence and future trials are needed to find out whether in patients with NSTE ACS hs cTn I/T tests should be combined with other tests, such as a test of B-type natriuretic peptide or NT-proBNP. Show less
Boden, H.; Ahmed, T.A.N.; Velders, M.A.; Hoeven, B.L. van der; Hoogslag, G.E.; Bootsma, M.; ... ; Schalij, M.J. 2013
The clinical use of advanced imaging modalities for early determination of infarct size and prognosis is limited. As a specific indicator of myocardial necrosis, cardiac troponin T(cTnT) can be... Show moreThe clinical use of advanced imaging modalities for early determination of infarct size and prognosis is limited. As a specific indicator of myocardial necrosis, cardiac troponin T(cTnT) can be used as a surrogate measure for this purpose. The present study sought to investigate the use of peak and serial 6-hour fixed-time high-sensitive (hs) cTnT for estimation of infarct size, left ventricular (LV) function, and prognosis in consecutive patients with ST-segment elevation myocardial infarction. The infarct size was expressed as the 48-hour cumulative creatine kinase release. LV function at 3 months was assessed using the echocardiographic wall motion score index and LV ejection fraction using radionuclide ventriculography. Adverse outcomes, comprising all-cause death, implantable cardioverter-defibrillator implantation, or hospitalization for heart failure, were recorded at 1 year of follow-up. In 188 patients, the peak and all fixed-time values correlated significantly with the 48-hour cumulative creatine kinase release, wall motion score index, and LV ejection fraction. The hs-cTnT value at 24 hours demonstrated the greatest correlation (r= 0.86, r=0.47, and r=−0.59, respectively; p <0.001 for all). In the multivariate regression models adjusted for the clinical parameters, almost all were independently associated with the 48-hour cumulative creatine kinase release, wall motion score index, and LV ejection fraction, with the hs-cTnT value at 24 hours having the largest effect. Moreover, all cTnT values independently predicted adverse outcomes, again, with the hs-cTnT value at 24hours showing the largest influence (hazard ratio 3.77, 95% confidence interval 2.12 to 6.73, p<0.001). In conclusion, not only peak, but all fixed-time hs-cTnT values were associated with infarct size, LV function at 3 months, and adverse outcomes 1 year after ST-segment elevation myocardial infarction. The value 24 hours after the onset of symptoms had the closest associations with all outcomes. Therefore, serial sampling for a peak value might be redundant. Show less
Ypey, D.L.; Meerwijk, W.P.M. van; Umar, S.; Pijnappels, D.A.; Schalij, M.J.; Laarse, A. van der 2012
Depolarization-induced automaticity (DIA) of cardiomyocytes is the property of those cells to generate pacemaker cell-like spontaneous electrical activity when subjected to a depolarizing current.... Show moreDepolarization-induced automaticity (DIA) of cardiomyocytes is the property of those cells to generate pacemaker cell-like spontaneous electrical activity when subjected to a depolarizing current. This property provides a candidate mechanism for generation of pathogenic ectopy in cardiac tissue. The purpose of this study was to determine the biophysical mechanism of DIA in terms of the ion conductance properties of the cardiomyocyte membrane. First, we determined, by use of the conventional whole-cell patch-clamp technique, the membrane conductance and DIA properties of ventricular cardiomyocytes isolated from adult rat heart. Second, we reproduced and analysed DIA properties by using an adapted version of the experimentally based mathematical cardiomyocyte model of Pandit et al. (Biophys J 81:3029-3051 2001, Biophys J 84:832-841 2003) and Padmala and Demir (J Cardiovasc Electrophysiol 14:990-995 2003). DIA in 23 rat cardiomyocytes was a damped membrane potential oscillation with a variable number of action potentials and/or waves, depending on the strength of the depolarizing current and the particular cell. The adapted model was used to reconstruct the DIA properties of a particular cardiomyocyte from its whole-cell voltage-clamp currents. The main currents involved in DIA were an L-type calcium current (I (CaL)) and a slowly activating and inactivating Kv current (I (ss)), with linear (I (B)) and inward rectifier (I (K1)) currents acting as background currents and I (Na) and I (t) as modulators. Essential for DIA is a sufficiently large window current of a slowly inactivating I (CaL) combined with a critically sized repolarizing current I (ss). Slow inactivation of I (ss) makes DIA transient. In conclusion, we established a membrane mechanism of DIA primarily based on I (CaL), I (ss) and inward rectifier properties; this may be helpful in understanding cardiac ectopy and its treatment. Show less
Boden, H.; Ahmed, T.A.N.; Velders, M.A.; Hoeven, B.L. van der; Hoogslag, G.E.; Bootsma, M.; ... ; Schalij, M.J. 2012
