Biomedical subjects

Hugo A Katus

Publications and source records attributed to Hugo A Katus.

At least 109 records · Page 6Linked to original sources

PubMed2004

Biventricular hypertrophy in dogs with chronic AV block: effects of cyclosporin A on morphology and electrophysiology.

Chronic atrioventricular (AV) block (CAVB) and biventricular hypertrophy in dogs increase susceptibility to drug-induced polymorphic ventricular tachycardia (PVT). In various rodent models, cyclosporin A (CsA) prevented hypertrophy. A similar effect in the CAVB model would allow us to determine whether hypertrophy represents an epiphenomenon, the cause of electrophysiological changes, and/or the anatomic substrate for PVTs. Upon AV node ablation, 6 dogs were studied acutely (AAVB), 25 dogs were kept for 6 (6W) and 12 wk (12W), receiving no treatment [CTL-CAVB-6W (n=6) and CTL-CAVB-12W (n=7)] or a daily oral dose of 10-20 mg/kg CsA directly (n=6, CsA-CAVB-6W) or 6 wk after radio-frequency ablation (n=6, CsA-CAVB-12W). For the final study, dogs were anesthetized, and 60 needles were inserted into both ventricles and connected to a multiplexer mapping system. Local effective refractory periods (ERPs) were determined at 56 +/- 22 randomly selected sites (extrastimulus technique, basic cycle length=800 ms). Arrhythmias within 30 min after application of almokalant (0.34 micromol/kg iv) were registered. The hearts were then excised to obtain the heart weight-body weight index (HBWI). Compared with AAVB, CTL-CAVB-6W and CTL-CAVB-12W showed increased HBWI and ERP associated with PVT inducibility in none of six AAVB dogs, four of six CTL-CAVB-6W dogs, and one of seven CTL-CAVB-12W dogs. Compared with CTL-CAVB-6W and CTL-CAVB-12W, CsA-CAVB-6W and CsA-CAVB-12W partially prevented hypertrophy or led to a regression of hypertrophy without reducing ERP prolongation. Despite ERP prolongation, PVTs were no longer inducible with CsA treatment. Thus prolongation of refractoriness seems to provide the trigger, but hypertrophy provides the essential substrate for the induction of PVTs in this model.

Animals↗

PubMed2004

Inhibition of cardiac HERG currents by the DNA topoisomerase II inhibitor amsacrine: mode of action.

1 The topoisomerase II inhibitor amsacrine is used in the treatment of acute myelogenous leukemia. Although most anticancer drugs are believed not to cause acquired long QT syndrome (LQTS), concerns have been raised by reports of QT interval prolongation, ventricular fibrillation and death associated with amsacrine treatment. Since blockade of cardiac human ether-a-go-go-related gene (HERG) potassium currents is an important cause of acquired LQTS, we investigated the acute effects of amsacrine on cloned HERG channels to determine the electrophysiological basis for its proarrhythmic potential. 2 HERG channels were heterologously expressed in human HEK 293 cells and Xenopus laevis oocytes, and the respective potassium currents were recorded using patch-clamp and two-microelectrode voltage-clamp electrophysiology. 3 Amsacrine blocked HERG currents in HEK 293 cells and Xenopus oocytes in a concentration-dependent manner, with IC50 values of 209.4 nm and 2.0 microm, respectively. 4 HERG channels were primarily blocked in the open and inactivated states, and no additional voltage dependence was observed. Amsacrine caused a negative shift in the voltage dependence of both activation (-7.6 mV) and inactivation (-7.6 mV). HERG current block by amsacrine was not frequency dependent. 5 The S6 domain mutations Y652A and F656A attenuated (Y652A) or abolished (F656A, Y652A/F656A) HERG current blockade, indicating that amsacrine binding requires a common drug receptor within the pore-S6 region. 6 In conclusion, these data demonstrate that the anticancer drug amsacrine is an antagonist of cloned HERG potassium channels, providing a molecular mechanism for the previously reported QTc interval prolongation during clinical administration of amsacrine.

Amsacrine↗

PubMed2004

Influence of pretreatment systolic blood pressure on the effect of carvedilol in patients with severe chronic heart failure: the Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) study.

OBJECTIVES: We sought to evaluate the influence of pretreatment systolic blood pressure (SBP) on the efficacy and safety of carvedilol in patients with chronic heart failure (CHF). BACKGROUND: Although beta-blockers reduce the risk of death in CHF, there is little reported experience with these drugs in patients with a low pretreatment SBP, who may respond poorly to beta-blockade. METHODS: We studied 2,289 patients with severe CHF who participated in the Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial. RESULTS: Compared with placebo, carvedilol improved the clinical status and reduced the risk of death and the combined risk of death or hospitalization for any reason, for a cardiovascular reason, or for worsening heart failure (p < 0.001 for all). The relative magnitude of these benefits did not vary as a function of the pretreatment SBP (all interaction: p > 0.10). However, because patients with the lowest SBP were at highest risk of an event, they experienced the greatest absolute benefit from treatment with carvedilol. The lower the pretreatment SBP, the more likely that patients would report an adverse event, be intolerant of high doses of the study drug, or require permanent withdrawal of treatment (p < 0.001 for all). However, these risks were primarily related to the severity of the underlying illness and not to treatment with carvedilol. CONCLUSIONS: The current study provides little support for concerns about using beta-blockers (particularly those with vasodilatory actions) in patients with severe CHF who have a low SBP. Pretreatment blood pressure can identify patients who have the greatest need for risk reduction with carvedilol.

Adrenergic beta-Antagonists↗

PubMed2004

Inhibition of human ether-a-go-go-related gene potassium channels by alpha 1-adrenoceptor antagonists prazosin, doxazosin, and terazosin.

Human ether-a-go-go-related gene (HERG) potassium channels are expressed in multiple tissues including the heart and adenocarcinomas. In cardiomyocytes, HERG encodes the alpha-subunit underlying the rapid component of the delayed rectifier potassium current, I(Kr), and pharmacological reduction of HERG currents may cause acquired long QT syndrome. In addition, HERG currents have been shown to be involved in the regulation of cell proliferation and apoptosis. Selective alpha 1-adrenoceptor antagonists are commonly used in the treatment of hypertension and benign prostatic hyperplasia. Recently, doxazosin has been associated with an increased risk of heart failure. Moreover, quinazoline-derived alpha 1-inhibitors induce apoptosis in cardiomyocytes and prostate tumor cells independently of alpha1-adrenoceptor blockade. To assess the action of the effects of prazosin, doxazosin, and terazosin on HERG currents, we investigated their acute electrophysiological effects on cloned HERG potassium channels heterologously expressed in Xenopus oocytes and HEK 293 cells.Prazosin, doxazosin, and terazosin blocked HERG currents in Xenopus oocytes with IC(50) values of 10.1, 18.2, and 113.2 microM respectively, whereas the IC(50) values for HERG channel inhibition in human HEK 293 cells were 1.57 microM, 585.1 nM, and 17.7 microM. Detailed biophysical studies revealed that inhibition by the prototype alpha 1-blocker prazosin occurred in closed, open, and inactivated channels. Analysis of the voltage-dependence of block displayed a reduction of inhibition at positive membrane potentials. Frequency-dependence was not observed. Prazosin caused a negative shift in the voltage-dependence of both activation (-3.8 mV) and inactivation (-9.4 mV). The S6 mutations Y652A and F656A partially attenuated (Y652A) or abolished (F656A) HERG current blockade, indicating that prazosin binds to a common drug receptor within the pore-S6 region. In conclusion, this study demonstrates that HERG potassium channels are blocked by prazosin, doxazosin, and terazosin. These data may provide a hypothetical molecular explanation for the apoptotic effect of quinazoline-derived alpha1-adrenoceptor antagonists.

Adrenergic alpha-Antagonists↗

PubMed2004

Adrenergic regulation of the rapid component of the cardiac delayed rectifier potassium current, I(Kr), and the underlying hERG ion channel.

Ventricular arrhythmias are often precipitated by physical or emotional stress, in particular in patients with ischemic heart disease or hereditary long QT syndrome. Stimulation of the sympathetic nervous system in response to exercise or emotional stress causes activation of cardiac alpha- and beta-adrenoceptors. The rapid component of the delayed rectifier potassium current, I(Kr), and the underlying hERG potassium channel are critical for the regulation of heart rhythm. Recent experimental studies revealed that hERG/I(Kr) currents are modulated by alpha- and beta-adrenergic stimulation, providing a pathophysiological explanation for the increased incidence of arrhythmias during stress. This review summarizes the current knowledge on hERG/I(Kr) channel modulation by adrenergic activity. In addition, therapeutic approaches to future effective, more genotype-specific antiarrhythmic therapies are discussed.

Adrenergic alpha-Agonists↗

PubMed2004

Hypertrophy of the heart: a new therapeutic target?

Recent studies call into question the necessity of hypertrophic growth of the heart as a "compensatory" response to hemodynamic stress. These findings, coupled with recent progress in dissecting the molecular bases of hypertrophy, raise the prospect of suppressing hypertrophy without provoking circulatory insufficiency. In this article, we focus on signaling pathways that hold promise as potential targets for therapeutic intervention. We also summarize observations from animal models and clinical trials that suggest benefit from an antihypertrophic strategy.

Adaptation, Physiological↗

PubMed2004

NT-proBNP in severe chronic heart failure: rationale, design and preliminary results of the COPERNICUS NT-proBNP substudy.

BACKGROUND: Neither profiles nor prognostic value of cardiac N-terminal proBNP (NT-proBNP) have been prospectively evaluated in a sufficient number of patients with severe chronic heart failure (CHF) treated with carvedilol or placebo. METHODS: Baseline and follow-up plasma concentrations of NT-proBNP were measured in the European part of the COPERNICUS Trial. This study enrolled patients with an ejection fraction <25% and symptoms of CHF at rest or on minimal exertion, equally randomized to placebo or carvedilol. RESULTS: NT-proBNP concentrations were increased at baseline (mean+/-S.D.=579+/-822 pmol/l, median=322.5 pmol/l) with a marked decrease during follow-up in the carvedilol, but not in the placebo group. One-year mortality rates were 3.9, 12 and 27.9% in the lower, middle and upper tertiles of NT-proBNP, respectively. When mortality was calculated separately in the placebo and carvedilol group, rates were 0.8, 6.3 and 19.1% in the carvedilol treated but 6.7, 17.9 and 36.9% in the placebo treated patients. CONCLUSIONS: NT-proBNP was a powerful predictor of subsequent all-cause mortality in patients with severe CHF. This marker should therefore be further evaluated for risk stratification and monitoring of therapy in CHF.

Aged↗

PubMed2004

Reduced hemoglobin after heart transplantation is no independent risk factor for survival but is associated closely with impaired renal function.

BACKGROUND: Reduced hemoglobin (Hb) levels after heart transplantation (HTX) are common; however, there are only limited data on the association of posttransplant anemia with survival. METHODS: In the present study, the effect of Hb levels determined 7 to 12 months after HTX on survival was investigated in 156 heart transplant recipients (129 men and 27 women; age at transplantation, 51.3+/-10.45 years; follow-up, 6.77+/-3.6 years) by univariate and multivariate analyses including a broad range of clinical and demographic patient characteristics. RESULTS: Anemia by standard definition was found in 141 of 156 (91.6%) patients. According to Hb levels above or below the gender-specific median (men, 12.07 g/dL; women, 11.69 g/dL), patients were separated into a high- or low-Hb group, respectively. Kaplan-Meier analysis demonstrated significantly worse survival in the low-Hb group (P =0.033). Those patients showed significantly lower body weight, higher serum creatinine levels, and lower calculated creatinine clearance; the association of creatinine clearance and Hb levels was highly significant (P <0.0001). No differences were demonstrated between groups for age, preoperative cardiac diagnosis, diabetes, azathioprine, steroid or angiotensin-converting enzyme inhibitor medication, leukocyte and thrombocyte levels, rejection index, or cytomegalovirus (CMV) infection or serostatus. Multivariate Cox stepwise regression analysis demonstrated that CMV infection, diabetes, and female donor gender were significant risk factors for post-HTX survival. An Hb level below the median was, however, completely lost as a risk factor (P =0.44); instead, a strong trend for reduced creatinine clearance could be demonstrated (P =0.09). Subsequently, a significant association was demonstrated between low calculated creatinine clearance and impaired survival by separate Kaplan-Meier analysis (P =0.02). CONCLUSIONS: Low Hb levels after HTX do not represent an independent risk factor for reduced survival, but the demonstrated correlation appears to be primarily caused by concomitant functional renal impairment. Further studies will be required to investigate the role of post-HTX anemia as a sensitive indicator of functional renal impairment and the effects of anemia treatment on long-term survival.

Adult↗

PubMed2004

Phosphorylation of eukaryotic translation initiation factor 2Bepsilon by glycogen synthase kinase-3beta regulates beta-adrenergic cardiac myocyte hypertrophy.

Glycogen synthase kinase 3beta (GSK-3beta) negatively regulates cardiac hypertrophy. A potential target mediating the antihypertrophic effect of GSK-3beta is eukaryotic translation initiation factor 2Bepsilon (eIF2Bepsilon). Overexpression of GSK-3beta increased the cellular kinase activity toward GST-eIF2Bepsilon in neonatal rat cardiac myocytes, whereas LiCl (10 mmol/L) or isoproterenol (ISO) (10 micromol/L), a treatment known to inhibit GSK-3beta, decreased it. Immunoblot analyses using anti-S535 phosphospecific eIF2Bepsilon antibody showed that S535 phosphorylation of endogenous eIF2Bepsilon was decreased by LiCl or ISO, suggesting that GSK-3beta is the predominant kinase regulating phosphorylation of eIF2Bepsilon-S535 in cardiac myocytes. Decreases in eIF2Bepsilon-S535 phosphorylation were also observed in a rat model of cardiac hypertrophy in vivo. Overexpression of wild-type eIF2Bepsilon alone moderately increased cell size (+31+/-11%; P<0.05 versus control), whereas treatment of eIF2Bepsilon-transduced myocytes with LiCl (+73+/-22% versus eIF2Bepsilon only; P<0.05) or ISO (+84+/-33% versus eIF2Bepsilon only; P<0.05) enhanced the effect of eIF2Bepsilon. Overexpression of eIF2Bepsilon-S535A, which is not phosphorylated by GSK-3beta, increased cell size (+107+/-35%) as strongly as ISO (+95+/-25%), and abolished antihypertrophic effects of GSK-3beta, indicating that S535 phosphorylation of eIF2Bepsilon critically mediates antihypertrophic effects of GSK-3beta. Furthermore, expression of eIF2Bepsilon-F259L, a dominant-negative mutant, inhibited ISO-induced hypertrophy, indicating that eIF2Bepsilon is required for beta-adrenergic hypertrophy. Interestingly, expression of eIF2Bepsilon-S535A partially increased cytoskeletal reorganization, whereas it did not increase expression of atrial natriuretic factor gene. These results suggest that GSK-3beta is the predominant kinase mediating phosphorylation of eIF2Bepsilon-S535 in cardiac myocytes, which in turn plays an important role in regulating cardiac hypertrophy primarily through protein synthesis.

Adenoviridae↗

PubMed2004

Pro- and antiarrhythmic effects of fast cardiac pacing in a canine model of acquired long QT syndrome.

Increasing the heart rate is one option for suppressing bradycardia-dependent polymorphic ventricular tachycardias (PVTs). The mechanisms underlying preventive pacing in acquired forms of the long QT syndrome (LQTs) are still not fully understood. Using two needle electrodes, local effective refractory periods (ERPs) were determined in the left (LV) and right ventricle (RV) in 20 dogs with acute AV node ablation before continuous pacing, during a 20-min period of continuous fast pacing (Cl 300 ms, fastpac) and during a 35-min recovery period with slow (Cl 500 ms) pacing. This protocol was applied to control dogs (5 dogs) and dogs with pretreatment of the IKs blocking agent chromanol 293b (5 dogs, LQTs1), the IKr-blocking agent dofetilide (5 dogs, LQTs2) or a combination thereof (5 dogs). Fastpac resulted in a significant abbreviation of ERPs in control dogs and dogs receiving dofetilide or chromanol 293b. During recovery, shortening of ERPs persisted in the control group, but diminished in dogs with acquired LQTs. In dogs with LQTs2 fastpac could not suppress inhomogeneity of refractoriness during recovery. With pretreatment of dofetilide and chromanol 293b in combination, MAP duration during fastpac significantly increased (first beat: 256+/-6 ms vs. sixth beat: 278+/-9 ms, p<0.05) and fastpac-induced PVTs were evident. ERP shortening and reduced inhomogeneity of refractoriness might be one antiarrhythmic action of fastpac in dogs with acute AV-block. However, in the acquired LQTs1 and 2 beneficial effects of fastpac diminished and in a combination thereof fastpac-induced PVTs are likely.

Action Potentials↗

PubMed2004

Hypoxia-induced inhibition of whole cell membrane currents and ion transport of A549 cells.

In excitable cells, hypoxia inhibits K channels, causes membrane depolarization, and initiates complex adaptive mechanisms. It is unclear whether K channels of alveolar epithelial cells reveal a similar response to hypoxia. A549 cells were exposed to hypoxia during whole cell patch-clamp measurements. Hypoxia reversibly inhibited a voltage-dependent outward current, consistent with a K current, because tetraethylamonium (TEA; 10 mM) abolished this effect; however, iberiotoxin (0.1 microM) does not. In normoxia, TEA and iberiotoxin inhibited whole cell current (-35%), whereas the K-channel inhibitors glibenclamide (1 microM), barium (1 mM), chromanol B293 (10 microM), and 4-aminopyridine (1 mM) were ineffective. (86)Rb uptake was measured to see whether K-channel modulation also affected transport activity. TEA, iberiotoxin, and 4-h hypoxia (1.5% O(2)) inhibited total (86)Rb uptake by 40, 20, and 35%, respectively. Increased extracellular K also inhibited (86)Rb uptake in a dose-dependent way. The K-channel opener 1-ethyl-2-benzimidazolinone (1 mM) increased (86)Rb uptake by 120% in normoxic and hypoxic cells by activation of Na-K pumps (+60%) and Na-K-2Cl cotransport (+170%). However, hypoxic transport inhibition was also seen in the presence of 1-ethyl-2-benzimidazolinone, TEA, and iberiotoxin. These results indicate that hypoxia, membrane depolarization, and K-channel inhibition decrease whole cell membrane currents and transport activity. It appears, therefore, that a hypoxia-induced change in membrane conductance and membrane potential might be a link between hypoxia and alveolar ion transport inhibition.

Cell Line, Tumor↗

PubMed2004

S100A1 gene transfer: a strategy to strengthen engineered cardiac grafts.

BACKGROUND: Cardiac tissue replacement therapy, although a promising novel approach for the potential treatment of heart failure, still suffers from insufficient contractile support to the failing myocardium. Here, we explore a strategy to improve contractile properties of engineered heart tissue (EHT) by S100A1 gene transfer. METHODS: EHTs were generated from neonatal rat cardiomyocytes and transfected (MOI 10 PFU) with the S100A1 adenovirus (AdvS100A1, n = 25) while an adenovirus devoid of the S100A1 cDNA served as a control (AdvGFP, n = 30). Contractile properties of transfected EHTs were measured 7 days following gene transfer. RESULTS: Western blot analysis confirmed a 8.7 +/- 3.6-fold S100A1 protein overexpression in AdvS100A1-transfected EHTs (n = 4; P < 0.01) that increased maximal isometric force (mN; AdvGFP 0.175 +/- 0.03 vs. AdvS100A1 0.47 +/- 0.06; P < 0.05) at 0.4 mmol/L extracellular calcium concentration [Ca(2+)](e). In addition, S100A1 overexpression enhanced both maximal Ca(2+)-stimulated force generation (+81%; P < 0.05) and Ca(2+)-sensitivity of EHTs (EC50% [Ca(2+)](e) mM; AdvGFP 0.33 +/- 0.04 vs. AdvS100A1 0.21 +/- 0.0022; P < 0.05). The S100A1-mediated gain in basal graft contractility was preserved throughout a series of isoproterenol interventions (10(-9) to 10(-6) M). Physiological properties of EHTs resembling intact heart preparations were preserved. CONCLUSIONS: S100A1 gene transfer in EHT is feasible and augments contractile performance, while characteristic physiological features of EHT remain unchanged. Thus, specific genetic manipulation of tissue constructs prior to implantation should be part of an improved tissue replacement strategy in heart failure.

Adenoviridae↗

PubMed2004

Time-dependent changes of hs-CRP serum concentration in patients with non-ST elevation acute coronary syndrome.

BACKGROUND: Atherosclerosis is typically associated with a low-grade vascular inflammation that can be measured with the highly sensitive C-reactive protein (hs-CRP) assay. Actually, acute coronary syndromes are thought to result from plaque rupture which is induced by the inflammatory process in the atherosclerotic tissue. Therefore, it is interesting to discuss the value of follow-up measurements of hs-CRP in patients with coronary artery disease (CAD). PATIENTS AND METHODS: The hs-CRP concentration of 133 patients consecutively admitted with an acute coronary syndrome (ACS) was measured on admission and after 6 months. The final assessment after 3 years was structured by questionnaire. RESULTS: 17 cardiac events occurred within 6 months, 30 during the following 3 years. The hs-CRP levels (median +/- SEM) decreased significantly (p < 0.001) from baseline (3.9 +/- 1.3 mg/l) to follow-up (2.9 +/- 0.9 mg/l). Subdivision according to cardiac events during the first observation period confirmed this decrease in patients without events (baseline: 3.9 +/- 1.5 mg/l, follow-up: 2.9 +/- 0.9 mg/l; p < 0.001), whereas patients with events showed a persistent elevation (baseline: 3.8 +/- 0.9 mg/l, follow-up: 4.1 +/- 1.0 mg/l; p = 0.426). Patients who developed a further event during the 6-month period showed hs-CRP levels at follow-up that were > 60% of the initial level. Interestingly, 80% of the events within the following 3 years occurred in patients with an hs-CRP level above this discriminator. With a follow-up hs-CRP value above this discriminator the relative risk of suffering an event was 3.4 (95% confidence interval 1.27-8.9; p < 0.05). CONCLUSION: Patients with a non-ST elevation ACS who showed no event within 6 months are characterized by a decrease in hs-CRP levels from baseline to follow-up. Most events in the observation period of 3 years occurred in patients with follow-up hs-CRP levels > 60% of the initial level. Therefore, it was hypothesized that a repeated measurement of hs-CRP levels in CAD patients could help to discriminate those at high risk of further events.

Acute Disease↗

PubMed2004

[Diagnosis of ischemia].

Clinically, coronary artery disease (CAD) presents either as stable angina pectoris or as an acute coronary syndrome. Atypical chest pain or silent myocardial ischemia is not uncommon and may obscure the diagnosis of CAD. Whereas primary or secondary prevention is indicated in all cases with suspected or documented atherosclerosis, cardiac catheterization and revascularization therapy is restricted to patients with significant CAD. In order to detect hemodynamically significant coronary artery stenoses, exercise stress tests or noninvasive stress imaging are usually implemented in the diagnostic workup. By contrast, patients presenting with an acute coronary syndrome require an initial risk stratification for estimation of the acute thrombotic risk associated with the underlying vulnerable plaque. Consecutively, patients without high-risk features need a thorough noninvasive evaluation for the presence of significant CAD which is comparable to patients presenting with chronic stable angina pectoris.

Angina, Unstable↗

PubMed2004

Radiation therapy-induced electrical reset of an implantable cardioverter defibrillator device located outside the irradiation field.

Given the overlap in risk factors for cardiac and malignant disease, some patients carrying implantable cardioverter defibrillators (ICDs) may require radiotherapy. Although pacemaker malfunction caused by radiotherapy is well known, few data exist on interactions between ICDs and radiation therapy. This report presents a patient with a single-chamber ICD and a history of bronchial carcinoma. During radiotherapy, electrical restart of the ICD device had occurred, although the device was not located inside the irradiation field. This case report highlights the diagnostic challenge represented by the environment of therapeutic radiation.

Aged↗

PubMed2004

Hope for a broken heart?

Heart failure affects 23 million people worldwide and results from cardiac dysfunction characterized by decreased responsiveness to beta-adrenergic stimulation. A recent publication by W.J. Koch and colleagues highlights evidence for targeted beta-adrenergic receptor kinase (betaARK1) inhibition by gene transfer to improve contractile function and beta-adrenergic responsiveness in failing human myocardium. This proof-of-concept study has great importance for future heart failure therapy because it provides evidence for the therapeutic effectiveness of betaARK1 inhibition in failing human myocardium.

Adenoviridae↗

PubMed2004

A locus on chromosome 7 determines dramatic up-regulation of osteopontin in dystrophic cardiac calcification in mice.

Calcification of necrotic tissue is frequently observed in chronic inflammation and atherosclerosis. A similar response of myocardium to injury, referred to as dystrophic cardiac calcinosis (DCC), occurs in certain inbred strains of mice. We now examined a putative inhibitor of calcification, osteopontin, in DCC after transdiaphragmal myocardial freeze-thaw injury. Strong osteopontin expression was found co-localizing with calcification in DCC-susceptible strain C3H/HeNCrlBr, which exhibited low osteopontin plasma concentrations otherwise. Osteopontin mRNA induction was 20-fold higher than in resistant strain C57BL/6NCrlBr, which exhibited fibrous lesions without calcification and little osteopontin expression. Sequence analysis identified several polymorphisms in calcium-binding and phosphorylation sites in osteopontin cDNA. Their potential relevance for DCC was tested in congenic mice, which shared the osteopontin locus with C57BL/6NCrlBr, but retained a chromosomal segment from C3H/HeNCrlBr on proximal chromosome 7. These mice exhibited strong osteopontin expression and DCC comparable to C3H/HeNCrlBr suggesting that a trans-activator of osteopontin transcription residing on chromosome 7 and not the osteopontin gene on chromosome 5 was responsible for the genetic differences in osteopontin expression. A known osteopontin activator encoded by a gene on chromosome 7 is the transforming growth factor-beta1, which was more induced (3.5x) in C3H/HeNCrlBr than in C57BL/6NCrlBr mice.

Animals↗

PubMed2004

Admission troponin T, advanced age and male gender identify patients with improved myocardial tissue perfusion after abciximab administration for ST-segment elevation myocardial infarction.

The aim was to investigate the effect of abciximab on microvascular perfusion in different subgroups of patients undergoing direct PCI for acute STEMI. We enrolled 145 consecutive patients with TIMI grade 3 flow after direct PCI for acute STEMI. The GPIIb/IIIa inhibitor abciximab was administered in 57 patients (39.3%). Myocardial perfusion was the primary outcome measure and was assessed by analysis of cardiac troponin T wash-out. Treatment effects on myocardial perfusion and clinical outcome were tested for predefined subgroups including patients with an admission cTnT > or = 0.1 microg/L, diabetes mellitus, male gender, age > 70 years, and time from symptom onset to reperfusion > 6 hours. A significant improvement of cTnT wash-out was seen in patients with an admission cTnT > or = 0.1 microg/L, in males and in older patients. Improved tissue level reperfusion did not translate into a significant reduction of cardiac mortality or the incidence of the combined endpoint consisting of cardiac death, nonfatal reinfarction and need for target vessel revascularisation during 30 day- and long-term follow-up (mean 274 days). In conclusion, adjunctive administration of abciximab improves myocardial perfusion in patients with normal epicardial flow after direct PCI, particularly in patients with an cTnT > or = 0.1 microg/L on admission, age over 70 years and male gender.

Abciximab↗