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Showing papers in "Cardiovascular Research in 2003"


Journal ArticleDOI
TL;DR: The dataset confirms the widely-held belief that most drugs associated with TdP in humans are also associated with hERG K(+) channel block at concentrations close to or superimposed upon the free plasma concentrations found in clinical use.
Abstract: Objective To attempt to determine the relative value of preclinical cardiac electrophysiology data (in vitro and in vivo) for predicting risk of torsade de pointes (TdP) in clinical use. Methods Published data on hERG (or I(Kr)) activity, cardiac action potential duration (at 90% repolarisation; APD(90)), and QT prolongation in dogs were compared against QT effects and reports of TdP in humans for 100 drugs. These data were set against the free plasma concentrations attained during clinical use (effective therapeutic plasma concentrations; ETPC(unbound)). The drugs were divided into five categories: (1) Class Ia and III antiarrhythmics; (2) Withdrawn from market due to TdP; (3) Measurable incidence/numerous reports of TdP in humans; (4) Isolated reports of TdP in humans; (5) No reports of TdP in humans. Results Data from hERG (or I(Kr)) assays in addition to ETPC(unbound) data were available for 52 drugs. For Category 1 drugs, data for hERG/I(Kr) IC(50), APD(90), QTc in animals and QTc in humans were generally close to or superimposed on the ETPC(unbound) values. This relationship was uncoupled in the other categories, with more complex relationships between the data. In Category 1 (except amiodarone), the ratios between hERG/I(Kr) IC(50) and ETPC(unbound) (max) ranged from 0.1- to 31-fold. Similar ranges were obtained for drugs in Category 2 (0.31- to 13-fold) and Category 3 (0.03- to 35-fold). A large spread was found for Category 4 drugs (0.13- to 35700-fold); this category embraced an assortment of mechanisms ranging from drugs which may well be affecting I(Kr) currents in clinical use (e.g. sparfloxacin) to others such as nifedipine (35700-fold) where channel block is not involved. Finally, for the majority of Category 5 drugs there was a >30-fold separation between hERG/I(Kr) activity and ETPC(unbound) values, with the notable exception of verapamil (1.7-fold), which is free from QT prolongation in man; this is probably explained by its multiple interactions with cardiac ion channels. Conclusions The dataset confirms the widely-held belief that most drugs associated with TdP in humans are also associated with hERG K(+) channel block at concentrations close to or superimposed upon the free plasma concentrations found in clinical use. A 30-fold margin between C(max) and hERG IC(50) may suffice for drugs currently undergoing clinical evaluation, but for future drug discovery programmes, pharmaceutical companies should consider increasing this margin, particularly for drugs aimed at non-debilitating diseases. However, interactions with multiple cardiac ion channels can either mitigate or exacerbate the prolongation of APD and QT that would ensue from block of I(Kr) currents alone, and delay of repolarisation per se is not necessarily torsadogenic. Clearly, an integrated assessment of in vitro and in vivo data is required in order to predict the torsadogenic risk of a new candidate drug in humans.

1,411 citations


Journal ArticleDOI
TL;DR: Although hard evidence for a role of microparticles in cardiovascular diseases at present is still only limited, new evidence is accumulating rapidly to support this theory and new intervention strategies for prevention and treatment of cardiovascular diseases are being developed.
Abstract: Microparticles are membrane vesicles released from many different cell types. There are two mechanisms that can result in their formation, cell activation and apoptosis. In these two mechanisms, different pathways are involved in microparticle generation. Microparticle generation seems to be a well regulated process. Microparticles vary in size, phospholipid and protein composition. They have a potent pro-inflammatory effect, promote coagulation and affect vascular function. Since these processes are all involved in the pathogenesis of cardiovascular disease and circulating microparticle numbers are altered in many cardiovascular diseases, a role for microparticles in the pathogenesis of cardiovascular diseases is likely. Although hard evidence for a role of microparticles in cardiovascular diseases at present is still only limited, new evidence is accumulating rapidly to support this theory. Elucidation of the microparticle composition and the mechanisms involved in exertion of their effects will supply this evidence and enable us to develop additional intervention strategies for prevention and treatment of cardiovascular diseases.

567 citations


Journal ArticleDOI
TL;DR: Inhibiting mPTP opening during the first few minutes of reperfusion, using sanglifehrin-A, limits infarct size and protects myocytes from oxidative stress.
Abstract: Objective: The opening of the mitochondrial permeability transition pore (mPTP) in the first few minutes of post-ischaemic reperfusion is a critical determinant of reperfusion-induced cell death We hypothesised that the novel immunosuppressant, sanglifehrin-A (SFA), given at the time of reperfusion, protects the myocardium from ischaemia–reperfusion injury, by suppressing mPTP opening Methods: Isolated perfused rat hearts were subjected to 35 min ischaemia/120 min reperfusion, and were treated with (1) SFA (10 μM) or (2) DMSO vehicle for the first 15 min of reperfusion or (3) SFA (10 μM) after the first 15 min of reperfusion We examined the effect of SFA on mPTP opening directly, using a myocyte model of oxidative stress Laser illumination of adult rat myocytes loaded with the fluorophore, TMRM, generates oxidative stress, which induces mPTP opening (represented by mitochondrial membrane depolarisation) followed by rigour contracture Results: In the isolated perfused heart model, SFA, given during the first 15 min of post-ischaemic reperfusion, reduced the infarct-risk volume ratio from 439±25% in the control group to 238±42% with SFA ( p = 0001) However, when SFA was given after the first 15 min of reperfusion, there was no change in infarct size (438±57% with SFA vs 439±25% in control; p = NS), suggesting that SFA has to be present during the first 15 min of reperfusion to induce protection In the isolated adult myocyte model, SFA was shown to inhibit mPTP opening in the setting of oxidative stress, represented by an increase in the ROS threshold required to induce: mitochondrial membrane depolarisation (from 269±21 to 777±100 s; p <0001) and rigour contracture (from 613±14 to 1329±129 s; p <0001) Conclusions: Inhibiting mPTP opening during the first few minutes of reperfusion, using sanglifehrin-A, limits infarct size and protects myocytes from oxidative stress

444 citations


Journal ArticleDOI
TL;DR: The relevance of the cross-talk between inflammation and coagulation is underlined by the promising results in the treatment of severe systemic infection with modulators of coagulations and inflammation.
Abstract: Severe infection and inflammation almost invariably lead to hemostatic abnormalities, ranging from insignificant laboratory changes to severe disseminated intravascular coagulation (DIC). Systemic inflammation results in activation of coagulation, due to tissue factor-mediated thrombin generation, downregulation of physiological anticoagulant mechanisms, and inhibition of fibrinolysis. Pro-inflammatory cytokines play a central role in the differential effects on the coagulation and fibrinolysis pathways. Vice-versa, activation of the coagulation system may importantly affect inflammatory responses by direct and indirect mechanisms. Apart from the general coagulation response to inflammation associated with severe infection, specific infections may cause distinct features, such as hemorrhagic fever or thrombotic microangiopathy. The relevance of the cross-talk between inflammation and coagulation is underlined by the promising results in the treatment of severe systemic infection with modulators of coagulation and inflammation.

430 citations


Journal ArticleDOI
TL;DR: The administration of L-arginine has been shown to improve endothelium-dependent vascular function in subjects with high ADMA levels, and is becoming a goal for pharmacotherapeutic intervention.
Abstract: There is abundant evidence that the endothelium plays a crucial role in the maintenance of vascular tone and structure. One of the major endothelium-derived vasoactive mediators is nitric oxide (NO). Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthase. ADMA inhibits vascular NO production at concentrations found in pathophysiological conditions (i.e., 3-15 micromol/l); ADMA also causes local vasoconstriction when it is infused intraarterially. The biochemical and physiological pathways related to ADMA are now well understood: dimethylarginines are the result of the degradation of methylated proteins; the methyl group is derived from S-adenosylmethionine. Both ADMA and its regioisomer, SDMA, are eliminated from the body by renal excretion, whereas only ADMA, but not SDMA, is metabolized via hydrolytic degradation to citrulline and dimethylamine by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). DDAH activity and/or expression may therefore contribute to the pathogenesis of endothelial dysfunction in various diseases. ADMA is increased in the plasma of humans with hypercholesterolemia, atherosclerosis, hypertension, chronic renal failure, and chronic heart failure. Increased ADMA levels are associated with reduced NO synthesis as assessed by impaired endothelium-dependent vasodilation. In several prospective and cross-sectional studies, ADMA evolved as a marker of cardiovascular risk. With our increasing knowledge of the role of ADMA in the pathogenesis of cardiovascular disease, ADMA is becoming a goal for pharmacotherapeutic intervention. Among other treatments, the administration of L-arginine has been shown to improve endothelium-dependent vascular function in subjects with high ADMA levels.

373 citations


Journal ArticleDOI
TL;DR: These data show reduced atherosclerosis and Th1 activity in spite of increased serum cholesterol in IL-18 deficient apoE(-/-) mice, which support a proatherogenic role for IL- 18.
Abstract: Objective: Atherosclerosis is an inflammatory disease in which T helper 1 (Th1) immunity has been proposed to play an important role. Naive CD4+ T cells differentiate into interferon-γ (IFN-γ) producing Th1 effector cells when stimulated by interleukin-18 (IL-18) and IL-12. We wanted to directly test whether the Th1 pathway is proatherogenic. Methods: We bred IL-18−/− mice with apolipoprotein E−/− (apoE−/−) mice and assessed atherosclerosis in the aortic root of the offspring. Results: 24-week-old IL-18 deficient apoE−/− mice exhibited substantially reduced lesion size (93 866±11 273 vs. 144 019±9667 μm2 in IL-18+/+×apoE−/− mice, P = 0.005). Lesion cells in compound knockout mice displayed reduced I-Ab expression, implying reduced local IFN-γ stimulation. These mice also had an increased proportion of α-SM-actin+ smooth muscle cells, compatible with a more stable lesion phenotype. Immunoglobulin G (IgG) subclass analysis of antibodies to malondialdehyde-modified low density lipoprotein indicated increased Th2 and reduced Th1 helper to B cell antibody production. Surprisingly, serum cholesterol and triglyceride levels were significantly higher in IL-18−/−×apoE−/− mice in spite of their reduced atherosclerosis. However, no changes in lipoprotein cholesterol patterns were registered. Conclusion: These data show reduced atherosclerosis and Th1 activity in spite of increased serum cholesterol in IL-18 deficient apoE−/− mice. They support a proatherogenic role for IL-18.

349 citations


Journal ArticleDOI
TL;DR: This brief review summarizes the recently obtained evidence which illustrates the beneficial effects of the endogenously produced antioxidant, melatonin, in reducing tissue damage and reversing cardiac pathophysiology in models of experimental ischemia/reperfusion in humans.
Abstract: This brief review summarizes the recently obtained evidence which illustrates the beneficial effects of the endogenously produced antioxidant, melatonin, in reducing tissue damage and reversing cardiac pathophysiology in models of experimental ischemia/reperfusion. The report also describes the actions of other antioxidants, especially vitamin E and antioxidative enzymes, in altering the degree of ischemia/reperfusion damage in the heart. Based on the data available, melatonin seems to have advantages over other antioxidants tested in terms of ameliorating the hypoxia and reoxygenation-induced damage. While the bulk of the studies that have used melatonin to overcome cardiac injury following transient arterial occlusion and subsequent reperfusion have used pharmacological doses to achieve protection, two recent reports have further shown that merely reducing endogenous circulating concentrations of melatonin (by surgical removal of a source of melatonin, i.e. the pineal gland) exaggerates the degree of injury and reduces survival of animals as a result of induced ischemia/reperfusion of the heart. These findings are consistent with observations in other organs where the loss of physiological concentrations of melatonin results in increased oxidative damage during hypoxia and reoxygenation. These findings have implications for the elderly since in the aged endogenous levels of melatonin are naturally reduced thereby possibly predisposing them to more severe cardiac damage during a heart attack. To date, the bulk of the studies relating to the protective actions of melatonin in reducing cardiac ischemia/reperfusion injury have used the rat as the experimental model. Considering the high efficacy of melatonin in limiting ischemia/reperfusion damage as well as melatonin's low toxicity, the studies should be expanded to include other species and models of cardiac ischemia/reperfusion. The results of these investigations would help to clarify the potential importance of the use of melatonin in situations of oxidative damage to the heart in humans.

312 citations


Journal ArticleDOI
TL;DR: In the present review, remarkable historical data on Chagas' disease studies putting special emphasis on histopathological findings and pathogenetic theories as well as recent discoveries based on the use of advanced modern technologies in pathology and immunology are summarized.
Abstract: In the present review we have summarized remarkable historical data on Chagas' disease studies putting special emphasis on histopathological findings and pathogenetic theories as well as recent discoveries based on the use of advanced modern technologies in pathology and immunology. A unified theory that links almost all of these findings is proposed. Chronic cardiac Chagas' disease represents the result of a close interaction between the host and the parasite, causing different clinical pictures: patients with an efficient immune response may adequately circumvent the parasitic infection and the individual will develop the indeterminate form. Deficient immune response of the host and/or a high initial parasitemia favor an immune imbalance that might lead to development of a permanent inadequate immunological response against the parasite. The inflammatory response, which is probably recurrent, undergoing periods of more accentuated exacerbation, is most likely responsible for progressive neuronal damage, microcirculatory alterations, heart matrix deformations and consequent organ failure.

306 citations


Journal ArticleDOI
TL;DR: In vitro evidence suggests that MMP activity may facilitate atherosclerosis, plaque destabilization, and platelet aggregation and limited evidence from clinical studies supports a role of MMPs in the development of acute coronary syndromes.
Abstract: Objective To summarize the structure, function, and regulation of matrix metalloproteinases (MMPs) and to review the literature to date on their potential role in the pathogenesis of acute coronary syndromes. Methods A recursive strategy starting with a Medline Search for primary articles in the last decade, followed by identification of additional articles of interest among the cited literature in the primary articles, followed by identification of additional articles of interest cited in the secondary articles. Results MMPs play a central role in many fundamental processes in human health and disease. In vitro evidence suggests that MMP activity may facilitate atherosclerosis, plaque destabilization, and platelet aggregation. Limited evidence from clinical studies supports a role of MMPs in the development of acute coronary syndromes. Conclusions MMP activity likely contributes to the development of acute coronary syndromes and may be an important therapeutic target for future drug development.

306 citations


Journal ArticleDOI
TL;DR: The balance of Na+ fluxes in heart cells may be complex, but myocyte Na+ regulation is functionally important and merits focused attention as in this issue, which discusses six sarcolemmal Na+ influx pathways.
Abstract: Intracellular [Na+] ([Na+]i) is regulated in cardiac myocytes by a balance of Na+ influx and efflux mechanisms. In the normal cell there is a large steady state electrochemical gradient favoring Na+ influx. This potential energy is used by numerous transport mechanisms, including Na+ channels and transporters which couple Na+ influx to either co- or counter-transport of other ions and solutes. Six sarcolemmal Na+ influx pathways are discussed in relatively quantitative terms: Na+ channels, Na+/Ca2+ exchange, Na+/H+ exchange, Na+/Mg2+ exchange, Na+/HCO3- cotransport and Na+/K+/2Cl- cotransport. Under normal conditions Na+/Ca2+ exchange and Na+ channels are the dominant Na+ influx pathways, but other transporters may become increasingly important during altered conditions (e.g. acidosis or cell volume stress). Mitochondria also exhibit Na+/Ca2+ antiporter and Na+/H+ exchange activity that are important in mitochondrial function. These coupled fluxes of Na+ with Ca2+, H+ and HCO3- make the detailed understanding of [Na+]i regulation pivotal to the understanding of both cardiac excitation-contraction coupling and pH regulation. The Na+/K+-ATPase is the main route for Na+ extrusion from cells and [Na+]i is a primary regulator under physiological conditions. [Na+]i is higher in rat than rabbit ventricular myocytes and the reason appears to be higher Na+ influx in rat with a consequent rise in Na+/K+-ATPase activity (rather than lower Na+/K+-ATPase function in rat). This has direct functional consequences. There may also be subcellular [Na+]i gradients locally in ventricular myocytes and this may also have important functional implications. Thus, the balance of Na+ fluxes in heart cells may be complex, but myocyte Na+ regulation is functionally important and merits focused attention as in this issue.

298 citations


Journal ArticleDOI
TL;DR: The increased Ca(2+)-responsiveness of the contractile apparatus in end-stage failing human hearts cannot be explained by a shift in contractile protein isoforms, but results from the complex interplay between changes in the phosphorylation status of MLC-2 and TnI.
Abstract: Objective: The alterations in contractile proteins underlying enhanced Ca2+-sensitivity of the contractile apparatus in end-stage failing human myocardium are still not resolved. In the present study an attempt was made to reveal to what extent protein alterations contribute to the increased Ca2+-responsiveness in human heart failure. Methods: Isometric force and its Ca2+-sensitivity were studied in single left ventricular myocytes from non-failing donor (n=6) and end-stage failing (n=10) hearts. To elucidate which protein alterations contribute to the increased Ca2+-responsiveness isoform composition and phosphorylation status of contractile proteins were analysed by one- and two-dimensional gel electrophoresis and Western immunoblotting. Results: Maximal tension did not differ between myocytes obtained from donor and failing hearts, while Ca2+-sensitivity of the contractile apparatus (pCa50) was significantly higher in failing myocardium (ΔpCa50=0.17). Protein analysis indicated that neither re-expression of atrial light chain 1 and fetal troponin T (TnT) nor degradation of myosin light chains and troponin I (TnI) are responsible for the observed increase in Ca2+-responsiveness. An inverse correlation was found between pCa50 and percentage of phosphorylated myosin light chain 2 (MLC-2), while phosphorylation of MLC-1 and TnT did not differ between donor and failing hearts. Incubation of myocytes with protein kinase A decreased Ca2+-sensitivity to a larger extent in failing (ΔpCa50=0.20) than in donor (ΔpCa50=0.03) myocytes, abolishing the difference in Ca2+-responsiveness. An increased percentage of dephosphorylated TnI was found in failing hearts, which significantly correlated with the enhanced Ca2+-responsiveness. Conclusions: The increased Ca2+-responsiveness of the contractile apparatus in end-stage failing human hearts cannot be explained by a shift in contractile protein isoforms, but results from the complex interplay between changes in the phosphorylation status of MLC-2 and TnI.

Journal ArticleDOI
TL;DR: Early studies in heart failure patients with anemia suggest that rHuEpo therapy is safe and effective in reducing left ventricular hypertrophy, enhancing exercise performance and increasing ejection fraction.
Abstract: Erythropoietin is a hypoxia-induced hormone that is essential for normal erythropoiesis. The production of recombinant human erythropoietin (rHuEpo) has revolutionized the treatment of anemia associated with chronic renal failure and chemotherapy, and has been used as prophylaxis to prevent anemia after surgery. The erythropoietin receptor is widely distributed in the cardiovascular system, including endothelial cells, smooth muscle cells and cardiomyocytes. Epo has potentially beneficial effects on the endothelium including anti-apoptotic, mitogenic and angiogenic activities. On the other hand, some reports suggest that rHuEpo may have pro-thrombotic or platelet-activating effects. Hypertension develops in 20-30% of renal patients treated with rHuEpo. Many patients with heart failure have anemia. Despite some potential adverse effects, early studies in heart failure patients with anemia suggest that rHuEpo therapy is safe and effective in reducing left ventricular hypertrophy, enhancing exercise performance and increasing ejection fraction. Further studies are warranted to define the role of rHuEpo in chronic heart failure and other cardiovascular settings.

Journal ArticleDOI
TL;DR: Although significant progress has been made in generating cardiac cell lineage by the combination of genetically manipulative methods with selective culture conditions for cell transplantation therapy, one of the remaining future challenges for transplantation in humans is the immunological rejection of the engrafted cardiomyocytes.
Abstract: Embryonic stem (ES) cells may represent an alternative source of functionally intact cardiomyocytes for the causal treatment of cardiovascular diseases However, this requires cardiac-specific differentiation of stem cells and the selection of pure lineages consisting of early embryonic cardiomyocytes Therefore, an understanding of the basic mechanisms of heart development is essential for selective differentiation of embryonic stem cells into cardiac cells The development of cardiac cells from embryonic stem cells is regulated by several soluble factors and signalling molecules together with cardiac specific transcription factors such as the zinc-finger GATA proteins and Nkx-25 GATA-4 and Nkx-25 seem to be essential for heart development The use of enhanced green fluorescent protein (EGFP) under the control of cardiac-specific promoters in combination with the ES cell system has allowed for the functional characterisation of cardiac precursor cells Embryonic stem cell-derived cardiomyocytes developmentally express similar cardiac-specific proteins, ion channels and signalling molecules to that of adult cardiomyocytes Furthermore, identification of growth factors and signalling molecules under cell culture conditions is crucial for the selective cardiac differentiation of embryonic stem cells Therefore, serum-free culture conditions have to be established in order to examine the influence of different growth factors and signalling molecules on cardiac development and/or formation from ES cells Although significant progress has been made in generating cardiac cell lineage by the combination of genetically manipulative methods with selective culture conditions for cell transplantation therapy, one of the remaining future challenges for transplantation in humans is the immunological rejection of the engrafted cardiomyocytes

Journal ArticleDOI
TL;DR: A review of studies wherein myocytes or stem cells with myogenic potential have been transplanted into the heart and issues pertaining to the tracking and functional consequences of cell transplantation are discussed.
Abstract: Cellular transplantation is emerging as a potential mechanism with which to augment myocyte number in diseased hearts. To date a number of cell types have been shown to successfully engraft into the myocardium, including fetal, neonatal, and embryonic stem cell-derived cardiomyocytes, skeletal myoblasts, and stem cells with apparent cardiomyogenic potential. Here we provide a review of studies wherein myocytes or stem cells with myogenic potential have been transplanted into the heart. In addition, issues pertaining to the tracking and functional consequences of cell transplantation are discussed.

Journal ArticleDOI
TL;DR: AC inhibition prevented increases in tissue angiotensin II concentration, phosphorylated ERK expression, Bax/Bcl-2 ratio, and cellular apoptosis, but did not affect total cell death, leukocyte infiltration, JNK or p38 activation, and reduced butdid not eliminate tissue fibrosis.
Abstract: Objective: Augmented atrial apoptosis, angiotensin II expression, and related signalling pathway activation have been shown in clinical atrial fibrillation (AF), but their significance is poorly understood. This study evaluated temporal relationships between changes in atrial histopathology, selected signalling mediators, and AF promotion, as well as effects of angiotensin-converting enzyme (ACE) inhibition, in a canine model of congestive heart failure (CHF). Methods: Dogs were subjected to ventricular tachypacing (VTP) for varying periods up to 5 weeks. Apoptosis was assessed by terminal dUTP nick-end labelling (TUNEL) and DNA fragmentation. Protein expression was determined by Western blot, angiotensin II concentration by ELISA (tissue) and radioimmunoassay (plasma), and caspase-3 activity by enzymatic assay. Histopathological analyses were used to quantify fibrosis, inflammation, and cell death. Results: Significant apoptosis developed 24 h after VTP onset and persisted for 1 week, returning to baseline thereafter. Apoptosis was preceded by increases in tissue (but not plasma) angiotensin II concentration; enhanced expression of phosphorylated mitogen-activated protein (MAP) kinases p38, JNK, and ERK; and augmented ratios of the proapoptotic protein Bax to the antiapoptotic protein Bcl-2. Increased cell death, leukocyte infiltration, and caspase-3 activity occurred at the time of peak apoptosis. Apoptosis was followed by interstitial fibrosis, which peaked at 5 weeks. ACE inhibition (enalapril) prevented increases in tissue angiotensin II concentration, phosphorylated ERK expression, Bax/Bcl-2 ratio, and cellular apoptosis, but did not affect total cell death, leukocyte infiltration, JNK or p38 activation, and reduced but did not eliminate tissue fibrosis. Conclusions: AF-promoting atrial structural remodeling in experimental CHF involves angiotensin II-dependent and angiotensin II-independent pathways. Significant apoptosis occurs, but prevention of apoptosis by ACE inhibition only partially prevents atrial structural remodeling.

Journal ArticleDOI
TL;DR: This review article focuses on the molecular mechanisms and components involved in the pathogenesis of sepsis with a major emphasis on the endothelium.
Abstract: Sepsis is one of the major causes of mortality in critically ill patients and develops as a result of the host response to infection. A complex network of events is set into motion in the body by the infection and results in the pathogenesis of sepsis. This review article focuses on the molecular mechanisms and components involved in the pathogenesis of sepsis with a major emphasis on the endothelium. This includes sepsis-inducing bacterial components (e.g. endotoxins), cellular targets of these molecules and their responses, host reactions, intracellular and cytokine networks, individual susceptibility and new therapeutic targets in sepsis treatment.

Journal ArticleDOI
TL;DR: Oral supplementation with combined B vitamins during 8 weeks does not improve endothelium-dependent vasodilation in PAOD patients with hyperhomocyst(e)inemia, whereas L-arginine significantly improved endothelial function in these patients.
Abstract: This editorial refers to an article by K. Sydow et al . [11][1] published in Cardiovascular Research in 2003 (see [Box 1][2]). It is accompanied by an editorial by J.-L. Balligand (doi:10.1093/cvr/cvs233) as part of this Spotlight on Landmark Papers in Cardiovascular Research . ### 1.1 Hyperhomocysteinaemia In 1997, when we were designing our clinical study, hyperhomocysteinaemia was considered to be a potential independent cardiovascular risk factor.1,2 A variety of underlying causes, i.e. inherited enzyme defects, renal insufficiency, and acquired defects in homocysteine metabolism, had been discovered. Since B vitamins and folic acid are relevant cofactors for metabolizing homocysteine, their combined treatment had been proved to significantly lower homocysteine plasma concentrations. However, the impact of combined B vitamin treatment on cardiovascular disease had been considered controversial. ### 1.2 Endothelial dysfunction: role of nitric oxide and asymmetric dimethylarginine Nitric oxide (NO) plays a crucial role in regulating vascular homoeostasis. Mechanisms that lead to endothelial dysfunction include a reduced NO production and/or an increased inactivation of NO. Asymmetric dimethylarginine (ADMA) is an endogenous NO synthase (NOS) inhibitor. In 1992, Vallance et al. 3 demonstrated elevated ADMA plasma concentrations in patients with renal insufficiency and revealed that exogenous administration of ADMA resulted in endothelial dysfunction with a concomitant increase in blood pressure. By the time we initiated our clinical study, the plasma concentrations of ADMA were shown to be elevated in hypercholesterolaemic rabbits and in patients with peripheral arterial disease (PAD) and hypercholesterolaemia.4,5 There was initial evidence that hyperhomocysteinaemia was associated with the NO pathway and endothelial dysfunction in animals and humans.6,7 Homocysteine increases the oxidative degradation of NO through the formation of disulfides and the generation of hydrogen peroxide and superoxide anion. Interestingly, ADMA plasma concentrations increased rapidly after acute methionine loading in humans.8 This methionine-induced increase in ADMA and homocysteine concentrations resulted in impaired flow-dependent vasodilation of the … [1]: #ref-11 [2]: #F1

Journal ArticleDOI
TL;DR: CRP causes NF-kappaB activation which could lead to the induction of MCP-1, IL-6, and iNOS gene expression and activates the MAPK-->c-Fos/cJun-->AP-1 pathway, which may play a role in atherogenesis by activating VSMC.
Abstract: Objective: C-reactive protein (CRP) is an important cardiovascular risk factor. Although the role of CRP has been implicated in atherogenesis, its direct effects on vascular cells are poorly defined. Methods: We investigated the responses to CRP in vascular smooth muscle cells (VSMC). Results: The present study shows that CRP induces parallel activation of the redox-responsive transcription factors NF-kappa B (NF-κB) and AP-1 and increases the activity of the MAP kinases (MAPKs), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38MAPK, in VSMC. C-reactive protein increased the expression of early response genes, c-fos and c-jun and inflammatory genes, monocyte chemoattractant peptide (MCP-1) and interleukin-6 (IL-6). When VSMC were incubated with CRP, the inducible nitric oxide synthase (iNOS) promoter was activated. CRP alone was a weak inducer of NO production in VSMC as measured by determining nitrite levels, and interferon-γ alone was totally ineffective, whereas CRP plus interferon-γ was a powerful stimulus. This synergy for NO production corresponded to the results of iNOS mRNA expression analyzed by Northern blotting. The NF-κB activation caused by CRP was inhibited by 15-deoxy-12,14-prostaglandin J2 and the PPARγ activators, rosiglitazone and pioglitazone. Fluvastatin and cerivastatin also reduced the activation of NF-κB by CRP. Conclusions: CRP causes NF-κB activation which could lead to the induction of MCP-1, IL-6, and iNOS gene expression. CRP also activates the MAPK→c-Fos/cJun→AP-1 pathway. Thus, CRP may play a role in atherogenesis by activating VSMC.

Journal ArticleDOI
TL;DR: Studies on different subclones of P19 cells, and what they have taught us about cardiac differentiation and physiology are reviewed.
Abstract: Many different stem cell types have been shown to differentiate into cardiac muscle cells in vitro but P19 embryonal carcinoma (EC) cells were one of the first examples described and have been the most extensively characterized. P19 EC cells, isolated from an experimental embryo-derived teratocarcinoma in mice, are multipotent and can differentiate into cell types of all three germ layers. Because of their capacity to form cardiomyocytes however, they have been used to dissect the role of cardiac-specific transcription factors and upstream signalling pathways in cardiac cell differentiation. Furthermore, they have shed light on unique aspects of cardiac cell physiology during heart cell differentiation, including regulation of the proteins underlying the electrical and contractile systems. Here, we review studies on different subclones of P19 cells, and what they have taught us about cardiac differentiation and physiology.

Journal ArticleDOI
TL;DR: The finding that EPCs home to sites of neovascularization and differentiate into endothelial cells (ECs) in situ is consistent with 'vasculogenesis', a critical paradigm well described for embryonic neov arteries but proposed recently in adults in which a reservoir of stem or progenitor cells contributes to vascular organogenesis.
Abstract: The isolation of endothelial progenitor cells (EPCs) derived from bone marrow (BM) was an outstanding event in the recognition of 'de novo vessel formation' in adults occurring as physiological and pathological responses. The finding that EPCs home to sites of neovascularization and differentiate into endothelial cells (ECs) in situ is consistent with 'vasculogenesis', a critical paradigm well described for embryonic neovascularization, but proposed recently in adults in which a reservoir of stem or progenitor cells contributes to vascular organogenesis. EPCs have also been considered as therapeutic agents to supply the potent origin of neovascularization under pathological conditions. This review provides an update of EPC biology as well as highlighting their potential use for therapeutic regeneration.

Journal ArticleDOI
TL;DR: An overview of current insights into the multiple roles of FGF-2 in the myocardium, as they pertain to two basic phenomena: ischemia-reperfusion injury and cardiac hypertrophy, is given.
Abstract: Fibroblast growth factor-2 (FGF-2) is a potent regulator of many cellular functions and phenomena, including cell proliferation, differentiation, survival, adhesion, migration, motility and apoptosis, and processes such as limb formation, wound healing, tumorigenesis, angiogenesis, vasculogenesis and blood vessel remodeling. In the adult myocardium, FGF-2 is expressed by various cell types, including cardiomyocytes, fibroblasts and smooth muscle cells. The biological effects of FGF-2 in the myocardium are mediated by the high-affinity tyrosine kinase receptor FGFR-1, the major FGF receptor in the heart. Here, we give an overview of current insights into the multiple roles of FGF-2 in the myocardium, as they pertain to two basic phenomena: ischemia-reperfusion injury and cardiac hypertrophy. The first category includes roles for FGF-2 in cardioprotection, the inflammatory response, angiogenesis and vascular remodeling, while the second includes myocyte hypertrophy, fibrosis, and gap junction functioning (conduction). Given the strong evidence for FGF-2 as both a cardioprotective and angiogenic agent, the therapeutic potential of FGF-2 in the ischemic myocardium is discussed.

Journal ArticleDOI
TL;DR: Moderate, short-term aerobic exercise can restore carotid arterial compliance in previously sedentary postmenopausal women taking HRT.
Abstract: Objective: Carotid arterial compliance is reduced with age in sedentary estrogen-deficient women, contributing to the development of cardiovascular disorders. We determined the effects of regular aerobic exercise, hormone replacement therapy (HRT), and their interaction on carotid arterial compliance using a combination of cross-sectional and intervention study designs. Methods: Cross-sectionally, we studied three groups of healthy postmenopausal women (50–80 years): 20 sedentary not taking HRT; 24 sedentary taking HRT; and 14 endurance-trained not taking HRT; and 11 sedentary premenopausal controls (20–37 years). In the intervention study, 12 sedentary postmenopausal women (58±3 years) who were taking HRT were studied before and after participation in a 3-month aerobic exercise (walking) program. Carotid arterial compliance was measured via simultaneous common carotid artery ultrasound imaging and applanation tonometry. Results : Cross-sectional study . Carotid arterial compliance was lower ( P <0.001) in all three postmenopausal groups compared with premenopausal women. Among the postmenopausal groups, arterial compliance was 33–43% higher in the sedentary HRT and endurance-trained women than in their sedentary estrogen-deficient peers. Intervention study . Arterial compliance increased ( P <0.05) by ∼40% to levels that were no longer different than premenopausal women. Conclusions: HRT use and regular aerobic exercise are associated with augmented carotid arterial compliance in healthy postmenopausal women. Moderate, short-term aerobic exercise can restore carotid arterial compliance in previously sedentary postmenopausal women taking HRT.

Journal ArticleDOI
TL;DR: The observation of TWA hastening ventricular tachyarrhythmias in an extraordinary variety of clinical and experimental conditions suggest potential universality of T WA in the pathophysiological mechanism of sudden death, and the precise sequence of events which triggers sudden cardiac death remains elusive.
Abstract: For nearly 100 years, beat to beat alternation of T wave amplitude, termed T wave alternans (TWA), has been closely linked to electrical instability in the heart. TWA is now established among the strongest markers of susceptibility to sudden cardiac death. Since computer technology allows for detection of very subtle yet clinically significant TWA during standard exercise testing, TWA has been used increasingly as a noninvasive clinical tool for identifying and treating patients at risk for sudden cardiac death. The observation of TWA hastening ventricular tachyarrhythmias in an extraordinary variety of clinical and experimental conditions suggest potential universality of TWA in the pathophysiological mechanism of sudden death. High resolution optical mapping studies have shown that TWA arises from alternans of repolarization at the level of the ventricular myocyte. Cellular alternans is likely due to the actions of one or more ionic currents and is closely related to, if not directly dependent on, the kinetics of intracellular calcium cycling. Impairment in calcium cycling at the cellular and sub-cellular levels has been implicated in the mechanism of cellulcar alternans. Importantly, spatially discordant alternans between cells is most likely a consequence of heterogeneities of electrophysiological properties between cells which span the ventricular wall, serving to amplify spatial heterogeneities of repolarization, and forming a substrate for reentrant excitation. Through this mechanism, TWA is linked directly and mechanistically to the pathogenesis of arrhythmias. Although available data would suggest that TWA is certainly closely related to a mechanism of arrhythmogenesis, and is a strong marker of clinical risk, the precise sequence of events which triggers sudden cardiac death, and the potential role of TWA in this process remains elusive.

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TL;DR: HIF-1alpha is essential for proper cardiac development by modulating both neural crest migration and ventricle formation by modulation of neural crest Migration and ventRICle formation.
Abstract: Objectives: Previous studies have revealed the essential role of hypoxia-inducible factor-1α (HIF-1α), a basic helix-loop-helix transcription factor, in cardiovascular development We attempted to further characterize the underlying mechanisms resulting in abnormal cardiogenesis and defective angiogenesis in mice deficient for HIF-1α (HIF-1α−/−) Methods: We analyzed cardiovascular development in HIF-1α−/− embryos at both the macroscopic and microscopic level Gene expression was determined by RT-PCR, in situ hybridization and immunohistochemistry Embryonic survival was studied using whole embryo culture Results: HIF-1α deficiency caused cardia bifida in some embryos, while cardiac looping was disturbed in others These defects did not result from abnormal cardiomyocyte commitment or differentiation, but may relate to defective ventricle formation caused by reduced expression of myocyte enhancer factor 2C (MEF2C) and eHAND In addition, remodeling of the aortic outflow tract and cephalic blood vessels was abnormal in HIF-1α−/− embryos These malformations, together with the hypoplastic pharyngeal arches, are presumably induced by defective neural crest cell (NCC) migration Impaired migration might be related to insufficient levels of semaphorin-3A (Sema3A) Hyperoxia prolonged survival but only partially rescued the developmental program of cultured HIF-1α−/− embryos Conclusion: HIF-1α is essential for proper cardiac development by modulating both neural crest migration and ventricle formation

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TL;DR: Characterization of the redifferentiation capabilities of cultured adult cardiac myocytes in culture provides an important system for comparing cardiomyocytes differentiating from human stem cells and provides the basis for an in vitro transplantation model to study interaction and communication between primary adult and stem cell-derived cardiomeocytes.
Abstract: Aim: Determination of the phenotype of adult human atrial and ventricular myocytes based on gene expression and morphology. Methods: Atrial and ventricular cardiomyocytes were obtained from patients undergoing cardiac surgery using a modified isolation procedure. Myocytes were isolated and cultured with or without serum. The relative cell attachment promoting efficiency of several reagents was evaluated and compared. Morphological changes during long-term culture were assessed with phase contrast microscopy, morphometric analysis and immunocytochemistry or RT-PCR of sarcomeric markers including α-actinin, myosin light chain-2 (MLC-2) and the adhesion molecule, cadherin. Results: The isolation method produced viable rod-shaped atrial (16.6±6.0%, mean±S.E.; n = 5) and ventricular cells (22.4±8.0%, mean±S.E.; n = 5) in addition to significant numbers of apoptotic and necrotic cells. Cell dedifferentiation was characterized by the loss of sarcomeric structure, condensation and extrusion of sarcomeric proteins. Cells cultured with low serum recovered and assumed a flattened, spread form with two distinct morphologies apparent. Type I cells were large, had extensive sarcolemmal spreading, with stress fibers and nascent myofibrils, whilst type II cells appeared smaller, with more mature myofibril organisation and focal adhesions. Conclusion: Characterization of the redifferentiation capabilities of cultured adult cardiac myocytes in culture, provides an important system for comparing cardiomyocytes differentiating from human stem cells and provides the basis for an in vitro transplantation model to study interaction and communication between primary adult and stem cell-derived cardiomyocytes.

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TL;DR: Sph-1-P, derived from platelets and dephosphorylated on the cell surface, may induce the contraction of coronary artery smooth muscle cells through the S1P(2)/Rho signaling.
Abstract: Objectives: Sphingosine 1-phosphate (Sph-1-P), a bioactive lipid derived from activated platelets, may play an important role in coronary artery spasm and hence the pathogenesis of ischemic heart diseases, since we reported that a decrease in coronary blood flow was induced by this lysophospholipid in an in vivo canine heart model [Cardiovasc Res 46 (2000) 119] In this study, metabolism related to and cellular responses elicited by Sph-1-P were examined in human coronary artery smooth muscle cells (CASMCs) Methods and results: [3H]Sphingosine (Sph), incorporated into CASMCs, was converted to [3H]Sph-1-P intracellularly, but its stimulation-dependent formation and extracellular release were not observed Furthermore, the cell surface Sph-1-P receptors of S1P family (previously called EDG) were found to be expressed in CASMCs Accordingly, Sph-1-P seems to act as an extracellular mediator in CASMCs Consistent with Sph-1-P-elicited coronary vasoconstriction in vivo, Sph-1-P strongly induced CASMC contraction, which was inhibited by JTE-013, a newly-developed specific antagonist of S1P2 (EDG-5) Furthermore, C3 exoenzyme or Y-27632 inhibited the CASMC contraction induced by Sph-1-P, indicating Rho involvement Finally, exogenously-added [3H]Sph-1-P underwent a rapid degradation Since lipid phosphate phosphatases, ectoenzymes capable of dephosphorylating Sph-1-P, were expressed in CASMCs, Sph-1-P may be dephosphorylated by the ectophosphatases Conclusions: Sph-1-P, derived from platelets and dephosphorylated on the cell surface, may induce the contraction of coronary artery smooth muscle cells through the S1P2/Rho signaling

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TL;DR: Anti-viral and anti-inflammatory therapies should be developed for their potential to prevent or ameliorate dilated cardiomyopathy (DCM).
Abstract: Myocarditis is a complex disease because multiple pathogenetic mechanisms play a role. While these mechanisms appear to act in a chronological cascade, they undoubtedly overlap in some cases, rendering diagnosis and treatment difficult. Ultimately, dilated cardiomyopathy (DCM) may result. A multitude of still-circumstantial evidence points to a major role of viral myocarditis in the etiology of DCM. The common presence of viral genetic material and viral proteins in the myocardium of patients with DCM provides the most compelling evidence, but proof of causality is still lacking. Nevertheless, because of the striking increase in heart failure prevalence in recent years, anti-viral and anti-inflammatory therapies should be developed for their potential to prevent or ameliorate DCM.

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TL;DR: Evidence suggests that direct phosphorylation at residue serine-38 in SERCA2a activates enzyme function and enhances Ca(2+)-reuptake into the sarcoplasmic reticulum (SR) and result in an overall increased SR Ca( 2+)-load and enhanced contractility.
Abstract: The cardiac SR Ca(2+)-ATPase (SERCA2a) regulates intracellular Ca(2+)-handling and thus, plays a crucial role in initiating cardiac contraction and relaxation. SERCA2a may be modulated through its accessory phosphoprotein phospholamban or by direct phosphorylation through Ca(2+)/calmodulin dependent protein kinase II (CaMK II). As an inhibitory component phospholamban, in its dephosphorylated form, inhibits the Ca(2+)-dependent SERCA2a function, while protein kinase A dependent phosphorylation of the phospho-residues serine-16 or Ca(2+)/calmodulin-dependent phosphorylation of threonine-17 relieves this inhibition. Recent evidence suggests that direct phosphorylation at residue serine-38 in SERCA2a activates enzyme function and enhances Ca(2+)-reuptake into the sarcoplasmic reticulum (SR). These effects that are mediated through phosphorylation result in an overall increased SR Ca(2+)-load and enhanced contractility. In human heart failure patients, as well as animal models with induced heart failure, these modulations are altered and may result in an attenuated SR Ca(2+)-storage and modulated contractility. It is also believed that abnormalities in Ca(2+)-cycling are responsible for blunting the frequency potentiation of contractile force in the failing human heart. Advanced gene expression and modulatory approaches have focused on enhancing SERCA2a function via overexpressing SERCA2a under physiological and pathophysiological conditions to restore cardiac function, cardiac energetics and survival rate.

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TL;DR: Failing canine ventricular myocytes exhibit prominent depletion of T-tubules and changes in the density of a variety of proteins in both surface and T- Tubular sarcolemma but with preservation of the protein composition of junctional complexes.
Abstract: Objective: The T-tubule membrane network is integrally involved in excitation–contraction coupling in ventricular myocytes. Ventricular myocytes from canine hearts with tachycardia-induced dilated cardiomyopathy exhibit a decrease in accessible T-tubules to the membrane-impermeant dye, di8-ANNEPs. The present study investigated the mechanism of loss of T-tubule staining and examined for changes in the subcellular distribution of membrane proteins essential for excitation–contraction coupling. Methods: Isolated ventricular myocytes from canine hearts with and without tachycardia-induced heart failure were studied using fluorescence confocal microscopy and membrane fractionation techniques using a variety of markers specific for sarcolemmal and sarcoplasmic reticulum proteins. Results: Probes for surface glycoproteins, Na/K ATPase, Na/Ca exchanger and Cav1.2 demonstrated a prominent but heterogeneous reduction in T-tubule labeling in both intact and permeabilised failing myocytes, indicating a true depletion of T-tubules and associated membrane proteins. Membrane fractionation studies showed reductions in L-type Ca2+ channels and β-adrenergic receptors but increased levels of Na/Ca exchanger protein in both surface sarcolemma and T-tubular sarcolemma-enriched fractions; however, the membrane fraction enriched in junctional complexes of sarcolemma and junctional sarcoplasmic reticulum demonstrated no significant changes in the density of any sarcolemmal protein or sarcoplasmic reticulum protein assayed. Conclusion: Failing canine ventricular myocytes exhibit prominent depletion of T-tubules and changes in the density of a variety of proteins in both surface and T-tubular sarcolemma but with preservation of the protein composition of junctional complexes. This subcellular remodeling contributes to abnormal excitation–contraction coupling in heart failure.

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TL;DR: Cholesterol-enriched diet-induced hyperlipidemia leads to an increase in cardiac ONOO(-) formation and a decrease in the bioavailability of NO which contributes to the deterioration of cardiac performance and may lead to further cardiac pathologies.
Abstract: Objective: We investigated the influence of experimental hyperlipidemia on the formation of cardiac NO, superoxide, and peroxynitrite (ONOO−) in rat hearts. Methods: Wistar rats were fed 2% cholesterol-enriched diet or normal diet for 8 weeks. Separate groups of normal and hyperlipidemic rats were injected twice intraperitoneally with 2×20 μmol/kg FeTPPS (5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-iron[III]), a ONOO− decomposition catalyst, 24 h and 1 h before isolation of the hearts. Results: A cholesterol diet significantly decreased myocardial NO content, however, myocardial Ca2+-dependent and Ca2+-independent NO synthase activity and NO synthase protein level did not change. Myocardial superoxide formation and xanthine oxidase activity were significantly increased; however, cardiac superoxide dismutase activity did not change in the cholesterol-fed group. Dityrosine in the perfusate, a marker of cardiac ONOO− formation, and plasma nitrotyrosine, a marker for systemic ONOO− formation, were both elevated in hyperlipidemic rats. In cholesterol-fed rats, left ventricular end-diastolic pressure (LVEDP) was significantly elevated as compared to controls. Administration of FeTPPS normalized LVEDP in the cholesterol-fed group. Conclusion: We conclude that cholesterol-enriched diet-induced hyperlipidemia leads to an increase in cardiac ONOO− formation and a decrease in the bioavailability of NO which contributes to the deterioration of cardiac performance and may lead to further cardiac pathologies.