Regulation of phosphodiesterase 3 and inducible cAMP early repressor in the heart

Growing evidence suggests that multiple spatially, temporally, and functionally distinct pools of cyclic nucleotides exist and regulate cardiac performance, from acute myocardial contractility to chronic gene expression and cardiac structural remodeling. Cyclic nucleotide phosphodiesterases (PDEs), by hydrolyzing cAMP and cyclic GMP, regulate the amplitude, duration, and compartmentation of cyclic nucleotide-mediated signaling. In particular, PDE3 enzymes play a major role in regulating cAMP metabolism in the cardiovascular system. PDE3 inhibitors, by raising cAMP content, have acute inotropic and vasodilatory effects in treating congestive heart failure but have increased mortality in long-term therapy. PDE3A expression is downregulated in human and animal failing hearts. In vitro, inhibition of PDE3A function is associated with myocyte apoptosis through sustained induction of a transcriptional repressor ICER (inducible cAMP early repressor) and thereby inhibition of antiapoptotic molecule Bcl-2 expression. Sustained induction of ICER may also cause the change of other protein expression implicated in human and animal failing hearts. These data suggest that the downregulation of PDE3A observed in failing hearts may play a causative role in the progression of heart failure, in part, by inducing ICER and promoting cardiac myocyte dysfunction. Hence, strategies that maintain PDE3A function may represent an attractive approach to circumvent myocyte apoptosis and cardiac dysfunction.

AMP-Activated Protein Kinase in the Heart

AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that is expressed in most mammalian tissues including cardiac muscle. Among the multiple biological processes influenced by AMPK, regulation of fuel supply and energy-generating pathways in response to the metabolic needs of the organism is fundamental and likely accounts for the remarkable evolutionary conservation of this enzyme complex. By regulating the activity of acetyl-coenzyme A carboxylase, AMPK affects levels of malonyl-coenzyme A, a key energy regulator in the cell. AMPK is generally quiescent under normal conditions but is activated in response to hormonal signals and stresses sufficient to produce an increase in AMP/ATP ratio, such as hypoglycemia, strenuous exercise, anoxia, and ischemia. Once active, muscle AMPK enhances uptake and oxidative metabolism of fatty acids as well as increases glucose transport and glycolysis. Data from AMPK deficiency models suggest that AMPK activity might influence the pathophysiology and therapy of diabetes and increase heart tolerance to ischemia. Effects that are not as well understood include AMPK regulation of transcription. Different AMPK isoforms are found in distinct locations within the cell and have distinct functions in different tissues. A principal mode of AMPK activation is phosphorylation by upstream kinases (eg, LKB1). These kinases have a fundamental role in cell-cycle regulation and protein synthesis, suggesting involvement in a number of human disorders including cardiac hypertrophy, apoptosis, cancer, and atherosclerosis. The physiological role played by AMPK during health and disease is far from being clearly defined. Naturally occurring mutations affecting the nucleotide-sensing modules in the regulatory gamma subunit of AMPK lead to enzyme dysregulation and inappropriate activation under resting conditions. Glycogen accumulation ensues, leading to human disease manifesting as cardiac hypertrophy, accessory atrioventricular connections, and degeneration of the physiological conduction system. Whether AMPK is a key participant or bystander in other disease states and whether its selective manipulation may significantly benefit these conditions remain important questions.

Micronuclei, genetic polymorphisms and cardiovascular disease mortality in a nested case-control study in Italy

AIM

To validate the predictive value of micronuclei (MN) in peripheral blood lymphocytes (PBL) and glutathione-S-transferases (GSTs) polymorphisms (GSTM1 and GSTT1) for mortality risk (MR) of cardiovascular diseases (CVD).

METHODS

Blood samples from 1650 healthy subjects selected from the general population were collected between June 1991 and November 1993, and slides were immediately prepared for MN assessment. The vital status, or the cause of death, was monitored for all subjects until January 2005. At the end of the follow-up, 111 deaths were recorded and 39 CVD cases were observed (age range=42-88 years). Two thousand binucleated (BN) cells/subject were scored for the MN assay and GSTs genotypes were assessed on the DNA extracted from the blood or serum samples.

RESULTS

A significantly higher MN frequency was recorded for the case group in comparison with the control group (n=67, Kruskall-Wallis test, p=0.006) and GSTT1 null genotype was significantly less frequent in CVD patients (chi(2)-test, p=0.036). The influence of other factors were evaluated using a unconditional logistic regression that confirmed a significant association of GSTT1 positive genotype with an increased OR for CVD (OR=6.29, 95% CI 1.32-29.95) beside a significant effect of age (OR=1.13, 95% CI 1.03-1.26 year(-1)). Finally, subjects with an higher MN frequency showed a higher MR for CVD (Log-rank test, p=0.001).

CONCLUSIONS

MN confirmed to be a suitable cytogenetic biomarker for early prediction of CVD death. The GSTT1 positive genotype is associated with an increased MR for CVD.

Cilostazol in the management of vascular disease

Cilostazol is a potent type III phosphodiesterase inhibitor with pharmacological effects that include vasodilatation, inhibition of platelet activation and aggregation, inhibition of thrombosis, increased blood flow to the limbs, improvement in serum lipids with lowering of triglycerides and elevation of high density lipoprotein cholesterol, and inhibition of vascular smooth muscle cell growth. It operates through its action as endothelium-target antithrombotic therapy, achieving its effects by improving endothelial cell function and reducing the number of platelets partially activated by interacting with activated endothelial cells. Since receiving approval from the Food and Drug Administration in 1999 in the United States for the treatment on intermittent claudication secondary to peripheral arterial disease, new data on its role on the prevention of restenosis after percutaneous transluminal angioplasty and the secondary prevention of cerebral infarction have increased interest in the drug. The aim of this study is to review cilostazol's beneficial effects and adverse events, and to present the results of the major clinical trials.

RhoA/Rho-kinase pathway: much more than just a modulation of vascular tone. Evidence from studies in humans

RhoA/Rho-kinase signaling and its relationship/balance with the nitric oxide level, angiotensin II and vasopressors for cardiovascular pathophysiology is of increasing importance, and its involvement goes far beyond blood pressure regulation. The deep involvement of this pathway in cardiovascular biology is now known to include a wide spectrum of conditions relating to the long-term complications of hypertension, and in general of cardiovascular pathophysiology, such as changes in cardiovascular structure (remodeling) and the induction of atherosclerosis, involvement in the pathophysiological relationships between inflammation and hypertension, and in those between hypertension, glucose metabolism and insulin resistance. Studies from our laboratory have made an important contribution to the understanding of the cellular and molecular mechanisms mediated by the RhoA/Rho-kinase pathway, which include all the aspects of cardiovascular pathophysiology in which this pathway plays a role. In addition, if it is considered that our contribution to the clarification of these mechanisms only comes from studies in humans, their impact on the scenario of the RhoA/Rho-kinase pathway's biology, essentially supported by studies 'in vitro' or in animal models, is immediate. This review examines all the aspects of RhoA/Rho-kinase signaling in the light of the available data, and gives an updated and useful overall picture of its involvement in cardiovascular pathophysiology.

Associations between the CYBA 242C/T and the MPO –463G/A Polymorphisms, Oxidative Stress and Cardiovascular Disease in Chronic Kidney Disease Patients

Genetic variations in the NADPH/MPO system in chronic kidney disease (CKD) patients might lead to altered activity of these enzymes, and thus to altered risk for oxidative stress (OS) and cardiovascular disease (CVD). We evaluated the impact of 242C/T CYBA and -463G/A MPO polymorphisms on OS and CVD mortality in stage 5 CKD patients starting dialysis. Two hundred and fifty-seven patients were genotyped using Pyrosequencing. Plasmalogen [dimethylacetal (DMA) 16/C16:0] was used as OS marker. CVD was assessed from patient history and clinical symptoms. Prevalence of CVD was higher (35%) in GG patients (MPO) compared to AG (26%) and AA (0%) patients (p < 0.01). Patients with CC genotype (CYBA) had lower levels of DMA 16/C16:0 (ratio 0.071 +/- 0.003) compared to TT patients (0.089 +/- 0.006; p < 0.05). These patients also had increased CVD mortality compared to CT and TT patients (chi(2) 2.19; p < 0.05). We conclude that genetic variations in the NADPH/MPO system are associated with OS, presence of CVD and CVD-related mortality in CKD patients.

[The role of matrix metalloproteinases in the development of vascular complications of diabetes mellitus--clinical implications]

Cardiovascular complications are the leading cause of increasing and premature mortality in diabetic patients. Matrix metalloproteinases (MMPs) play an important role in the development and progression of vascular lesions. Matrix metalloproteinases are members of endopeptidases and are capable of degrading many extracellular matrix components. Results of recent studies indicated that non-pharmacological and pharmacological treatment of diabetes influenced disturbed system of metalloproteinases and their inhibitors. Clinical trials are being performed in hope that the selective MMP inhibitors reduce the progression of pathological vascular remodeling in diabetes. Further basic and clinical research is required to confirm hypothesis.

The therapeutic potential of phospholipase A2 inhibitors in cardiovascular disease

Leukocyte recruitment and the expression of pro-inflammatory cytokines are prevalent characteristics of early atherogenesis. Recently, several inflammatory mediators have been linked to atheroma formation and inflammatory pathways have been shown to promote thrombosis. The discovery of mast cells, activated T lymphocytes and macrophages in atherosclerotic lesions, the detection of human leukocyte antigen class II expression, and the finding of local secretion of several cytokines all suggest the involvement of immune and inflammatory mechanisms in the pathogenesis of atherosclerosis. Recent research suggests activation of protease activated receptors (PAR) on the surface of endothelial cells may play a role in general mechanisms of inflammation. In previous studies, our laboratory has demonstrated that thrombin (which activates PAR-1) and tryptase (which activates PAR-2) stimulation of endothelial cells results in activation of calcium-independent phospholipase A(2) (iPLA(2)). iPLA(2) plays a critical role in the synthesis of membrane phospholipid-derived inflammatory mediators such as arachidonic acid, platelet activating factor (PAF), and prostaglandins, all demonstrated to be central in both the initiation and propagation of the inflammatory response. Activation of iPLA(2) results in release of choline lysophospholipids from endothelial cells, these metabolites may contribute to the initiation of ventricular arrhythmias following myocardial ischemia as a direct result of incorporation into the myocyte sarcolemma. This biochemical event represents a direct link between occlusion of a coronary vessel and the nearly immediate initiation of arrhythmogenesis often seen in myocardial ischemia.

Cardiovascular therapeutic aspects of soluble epoxide hydrolase inhibitors

Soluble epoxide hydrolase (sEH) is an enzyme responsible for the conversion of lipid epoxides to diols by the addition of water. Biological actions on the cardiovascular system that are attributed to epoxides include vasodilation, antiinflammatory actions and vascular smooth muscle cell antimigratory actions. Conversion of arachidonic acid epoxides to diols by sEH diminishes the beneficial cardiovascular properties of these epoxyeicosano-ids. Cardiovascular diseases in animal models and humans have been associated with decreased epoxygenase activity or increased sEH activity and these changes are responsible for the progression of the disease state. More recently, sEH gene polymorphisms in the human population have been associated with increased risk for cardiovascular diseases. Thus the biological actions of epoxyeicosanoids and the sEH enzyme are ideal therapeutic targets for cardiovascular diseases. The rapid development of 1,3-disubstituted urea based sEH inhibitors over the past five years has resulted in a number of studies demonstrating cardiovascular protection. sEH inhibitors have antihypertensive and antiinflammatory actions and have been demonstrated to decrease cerebral ischemic and renal injury in rat models of hypertension. These findings of beneficial actions in animal models of disease position the sEH enzyme as a promising therapeutic target for cardiovascular diseases.

p38 mitogen-activated protein kinase plays a critical role in the control of energy metabolism and development of cardiovascular diseases

p38 mitogen-activated protein kinase (p38) is a member of MAP kinase family. Its wide-spectrum roles in the control of energy metabolism have been indicated in numerous studies. p38 participates in the energy metabolism in all major tissues/organs involved in the control of energy metabolism, including adipose tissue, skeletal muscles, islet cells, and liver. In white adipose tissue, p38 plays an important role in adipose differentiation and glucose uptake although it is still inconclusive whether this role of p38 is stimulatory or inhibitory. The stimulatory role of p38 in transcription of the uncoupling protein 1 (UCP1) gene in brown adipose tissue is relatively clear. A fundamental role for p38 in the differentiation of skeletal muscles and mitochondrial biogenesis in skeletal muscles is rather definitive although the role of p38 in glucose uptake of skeletal muscles remains controversial. In islet cells, p38 appears to be involved in beta-cell apoptosis. p38 has been indicated in the control of preproinsulin gene transcription, but remains controversial. However, it seems clear that p38 does not play a significant role in insulin secretion. In the liver, p38 plays a central role in hepatic glucose and lipid metabolism. Activation of p38 participates in the processes to increase blood glucose levels through reducing glycogen synthesis and increasing hepatic gluconeogenesis. p38 appears to prevent fat storage by inhibiting hepatic lipogenesis and promoting fatty acid oxidation in the liver. Additionally, p38 may play a critical role in cholesterol metabolism by regulating expression of the LDLR gene and bile metabolism. p38 does not only participate in various physiological and pathophysiological processes in cardiomyocytes, but also is heavily involved in the development of atherosclerotic lessions through its influences on monocytes/macrophages, vascular endothelial cells, and vascular smooth muscle cells.

Association between lipoprotein-associated phospholipase A2 and cardiovascular disease: a systematic review

OBJECTIVE

To estimate the association between plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) levels and cardiovascular disease (CVD).

METHODS

We searched MEDLINE (January 1, 1985, through September 30, 2006), the Cochrane library (from inception through 2006), conference proceedings, and reference sections of obtained articles and contacted experts for unpublished studies. Eligible studies were cohorts with 1 year or more of follow-up or case-control designs that provided risk estimates for CVD according to blood levels of Lp-PLA2 that were unadjusted or adjusted for conventional CVD risk factors. We used random-effects meta-analysis to estimate the association between Lp-PLA2 and CVD risk and conducted preplanned subgroup analyses to identify risk-subgroup interactions that could explain between-study differences.

RESULTS

We found 14 eligible studies (N = 20,549 patients) that reported either Lp-PLA2 plasma activity (n = 5) or an immunoassay that measured the plasma concentration (n = 9). The meta-analytic estimate from the unadjusted odds ratio for the association between elevated Lp-PLA2 levels and CVD risk was 1.51 (95% confidence interval, 1.30-1.75) and from the odds ratio adjusted for conventional CVD risk factors was 1.60 (95% confidence interval, 1.36-1.89). Differences in study methods explained differences in results across studies.

CONCLUSIONS

Lipoprotein-associated phospholipase A2 is significantly associated with CVD. The risk estimate appears to be relatively unaffected by adjustment for conventional CVD risk factors. Measurement of Lp-PLA2 may be useful in CVD risk stratification. In addition, Lp-PLA2 may represent a potential therapeutic target for CVD risk reduction.

Smoking and atherosclerotic cardiovascular disease in women with lower levels of serum cholesterol

This cohort study of Koreans examines the relationship between smoking on atherosclerotic cardiovascular disease (ASCVD) and whether serum levels of total cholesterol modify the impact of smoking on ASCVD. A 10-year prospective cohort study was carried out on 234,399 Korean women, ranging 40-69 years of age who received health insurance from the National Health Insurance Corporation and had a medical evaluation in 1993. The main outcome measures were hospital admissions and deaths from ischemic heart disease (IHD), cerebrovascular disease (CVD), and total ASCVD. At baseline, 13,696 (5.8%) were current smokers and 105,755 (45.1%) had a total cholesterol <200mg/dl. Between 1994 and 2003, 4534 IHD (176/100,000 person year), 7961 CVD (310/100,000 person year), and 2418 other ASCVD events (94/100,000 person year) occurred. In multivariate Cox proportional hazard models controlling for age, hypertension, hypercholesterolemia, diabetes and alcohol drinking, current smoking increased the risk of IHD [hazard ratio (HR)=1.7 (95% CI: 1.5-1.9)], CVD [HR=1.6 (95% CI: 1.5-1.6)], and total ASCVD events [HR=1.6 (95% CI: 1.5-1.7)]. Throughout the range of serum cholesterol levels, current smoking significantly increased the risk of myocardial infarction and CVD, but not angina pectoris. There was no evidence of an interaction between smoking and serum cholesterol (p for interaction=0.469, 0.612, and 0.905 for IHD, CVD, and total ASCVD, respectively). This study demonstrated that smoking was a major independent risk factor for IHD, CVD and ASCVD in Korean women. A low cholesterol level confers no protective benefit against smoking-related ASCVD.

Regulation of endothelial and myocardial NO synthesis by multi-site eNOS phosphorylation

The controlled regulation of nitric oxide (NO) synthesis in endothelial cells and cardiomyocytes by the endothelial form of nitric oxide synthase (eNOS or NOS3) is essential for cardiovascular health. In recent years, a picture of complex and precise regulation of eNOS activity involving multi-site phosphorylation of specific serine and threonine residues has emerged. Regulation of endothelial NO synthesis by multi-site eNOS phosphorylation occurs in response to a wide variety of humoral, mechanical and pharmacological stimuli. This regulation involves numerous kinases and phosphatases, as well as interactions with other aspects of eNOS regulation such as Ca(2+) flux, protein-protein interactions and regulation of subcellular localization. Phosphorylation of eNOS-Ser(1177) close to the carboxy-terminal is a critical requirement for eNOS activation. In addition, phosphorylation of eNOS-Ser(633) in the flavin mononucleotide (FMN) binding domain also increases eNOS activity and appears particularly important for the maintenance of NO synthesis after initial activation by Ca(2+) flux and Ser(1177) phosphorylation. In contrast, NO synthesis is inhibited by phosphorylation of eNOS-Thr(495), which interferes with the binding of calmodulin to the eNOS calmodulin-binding domain. Regulated phosphorylation of eNOS also occurs at eNOS-Ser(114) and eNOS-Ser(615); however, the functions of these phosphorylation sites remain controversial. This review summarizes the present knowledge of the regulation of NO synthesis by multi-site eNOS phosphorylation and its relationship to other mechanisms of eNOS regulation. This progress in understanding important mechanisms controlling endothelial NO synthesis creates new opportunities to understand and potentially treat cardiovascular diseases characterized by deficient NO synthesis.

NOS3 polymorphisms, cigarette smoking, and cardiovascular disease risk: the Atherosclerosis Risk in Communities study

OBJECTIVE

Endothelial nitric oxide synthase (NOS3) activity and cigarette smoking significantly influence endothelial function. We sought to determine whether cigarette smoking modified the association between NOS3 polymorphisms and risk of coronary heart disease or stroke.

METHODS

All 1085 incident coronary heart disease cases, all 300 incident ischemic stroke cases, and 1065 reference individuals from the Atherosclerosis Risk in Communities study were genotyped for the T-786C and E298D polymorphisms in NOS3. Using a case-cohort design, associations between genotype/haplotype and disease risk were evaluated by multivariable proportional hazards regression. Multiplicative scale interaction testing evaluated the influence of cigarette smoking history at baseline on these associations.

RESULTS

In Caucasians, association between E298D genotype and risk of coronary heart disease was significantly modified by current smoking status (interaction P=0.013), with the highest risk observed in smokers carrying the variant D298 allele relative to nonsmokers carrying two E298 alleles (adjusted hazard rate ratio 2.07, 95% confidence interval 1.39-3.07). In African-Americans, association between T-786C genotype and risk of ischemic stroke was significantly modified by pack-year smoking history (interaction P=0.037), with the highest risk observed in >or=20 pack-year smokers carrying the variant C-786 allele relative to <20 pack-year smokers carrying two T-786 alleles (adjusted hazard rate ratio 4.03, 95% confidence interval 1.54-10.6).

CONCLUSIONS

An interaction between the E298D and T-786C polymorphisms in NOS3, cigarette smoking, and risk of incident coronary heart disease and ischemic stroke events appears to exist, suggesting a potential complex interplay between genetic and environmental factors and cardiovascular disease risk.

Rho kinase as potential therapeutic target for cardiovascular diseases: opportunities and challenges

Rho kinase (ROCK) belongs to a family of Ser/Thr protein kinases that are activated via interaction with the small GTP-binding protein RhoA. Growing evidence suggests that RhoA and ROCK participate in a variety of important physiological functions in vasculature including smooth muscle contraction, cell proliferation, cell adhesion and migration, and many aspects of inflammatory responses. As these processes mediate the onset and progression of cardiovascular disease, modulation of the Rho/ROCK signalling pathway is a potential strategy for targeting an array of cardiovascular indications. Two widely employed ROCK inhibitors, fasudil and Y-27632, have provided preliminary but compelling evidence supporting the potential cardiovascular benefits of ROCK inhibition in preclinical animal disease models and in the clinic. This review summarises the molecular biology of ROCK and its biological functions in smooth muscle, endothelium and other vascular tissues. In addition, there will be a focus on recent progress demonstrating the benefits of ROCK inhibition in several animal models of cardiovascular diseases. Finally, recent progress in the identification of novel ROCK inhibitors and challenges associated with their development for clinical use will be discussed.

Cyclooxygenase-2 Inhibition Increases Mortality, Enhances Left Ventricular Remodeling, and Impairs Systolic Function After Myocardial Infarction in the Pig

BACKGROUND

Cyclooxygenase (COX)-2 expression in the heart increases after myocardial infarction (MI). In murine models of MI, COX-2 inhibition preserves left ventricular dimensions and function. We studied the effect of selective COX-2 inhibition on left ventricular remodeling and function after MI in a pig model.

METHODS AND RESULTS

Twenty-two pigs were assigned to COX-2 inhibition with a COX-2 inhibitor (COX-2i; celecoxib 400 mg twice daily; n=14) or a control group (n=8). MI was induced by left circumflex coronary artery ligation, and the animals were euthanized 6 weeks later. Cardiac dimensions and function were assessed with echocardiography and conductance catheters. Infarct size and collagen density were analyzed with triphenyltetrazolium chloride staining and picrosirius red staining, respectively. COX-2 inhibition increased mortality compared with controls (50% versus 0%, P=0.022), whereas infarct size was similar (13.1+/-0.7% versus 14.1+/-0.1%, P=0.536). The decrease in thickness of the infarcted myocardial wall was more pronounced in the COX-2i group (60.6+/-9.6% versus 36.2+/-5.7%, P=0.001). End-diastolic volume was higher in the COX-2i group (133.9+/-33.5 versus 91.1+/-24.0 mL; P=0.021), as was the end-systolic volume at 100 mm Hg (81.7+/-27.8 versus 56.3+/-21.1 mL; P=0.037), which indicates that systolic function was more severely impaired. Infarct collagen density was lower after COX-2i treatment (25.3+/-3.9 versus 56.1+/-23.8 gray value/mm2; P=0.005).

CONCLUSIONS

In pigs, COX-2 inhibition after MI is associated with increased mortality, enhanced left ventricular remodeling, and impaired systolic function, probably due to decreased infarct collagen fiber density.

Myeloperoxidase predicts risk of vasculopathic events in hemizgygous males with Fabry disease

Fabry disease results in a global vasculopathy leading to early-onset stroke and renal and cardiac failure. We found that random myeloperoxidase in serum and plasma was significantly elevated in 73 consecutive male patients with Fabry disease. Random serum myeloperoxidase level in men predicted the risk of a Fabry vasculopathy-related event in subsequent years. Long-term enzyme replacement therapy did not reduce myeloperoxidase level or eliminate the risk of vasculopathic events.

[Age related changes of regulatory mechanisms of cardio-vascular system and significance of nitric oxide synthase in the norm and pathology]

The article sums up results of thirty-year period of studies of ontogenesis of autonomic nervous system conducted in laboratory of neuromorphology and electron microscopy. It contains discussion of pre- and postnatal ontogenesis of cardiovascular innervation and content of NO-synthase in cardiac ganglia at normal and pathological states. The studies included analysis of 12 series of human germs, examination of cardiovascular system of 23 human fetuses, and of material of 124 early autopsies of persons of different age who died suddenly or of some cardiac diseases. Methods of investigation included neurohistological, histochemical, and ultrastructural techniques; NO-synthase content was measured immunohistochemically. Data of time-frequency spectral analysis of heart rate variability of 43 subjects of different age ("normals" and with ischemic heart disease) are also presented. Conception of the neurotransmitter stage of ontogenesis of autonomic nervous system is formulated, and the phenomenon of early involution of its sympathetic part is described. Neurohistochemical data are compared with results of analysis of heart rate variability at normal and hypertensive states. The original data on nitric oxide synthase content in cardiac ganglia at normal state and coronary heart disease are provided. Prospects of immunohistochemical studies of central and autonomic nervous systems during ontogeny and at main cardiovascular diseases are outlined.

Influence of 677 C-->T polymorphism of methylenetetrahydrofolate reductase on medium-term prognosis after acute coronary syndromes

Various common genotypes of the polymorphism 677 C-->T of the methylenetetrahydrofolate reductase enzyme result in lower activity of the enzyme and in a subsequent increase in homocysteine levels. Many studies have analyzed the connection between this polymorphism and the beginning of coronary artery disease. However, conclusions have been controversial, and evidence of a connection between this polymorphism and the prognosis of coronary artery disease has been poorly evaluated. This prospective study evaluated the prognostic relevance of genotype TT in a cohort of 155 patients admitted to our hospital for treatment of an acute coronary syndrome accompanied by evidence of coronary atherosclerosis on coronary angiography. We found that patients with the genotype TT had higher homocysteine levels than did patients with the CT and CC genotypes (15.72 +/- 6.92 micromol/L vs 12.11 +/- 5.40 micromol/L and 12.01 +/- 4.25 micromol/L, P=0.01). After a mean follow-up of 13.4 +/- 7.4 months, we observed similar rates of major adverse cardiovascular events (CC, 29%; CT, 22%; and TT, 25%) and cardiovascular death (CC, 11%; CT, 7%; and TT, 8%). No difference in cardiovascular-death-free survival (log-rank analysis, 0.81; P=0.66) or event-free survival (log-rank analysis, 0.76; P=0.68) was found. The presence of genotype TT was not an independent predictor of prognosis after multivariate analysis by means of the Cox regression survival model. In conclusion, the presence of the TT genotype of the 677 C-->T polymorphism of the methylenetetrahydrofolate reductase enzyme was not related to prognosis in patients admitted to the hospital after an acute coronary syndrome.

Anti-inflammatory drugs in the 21st century

Historically, anti-inflammatory drugs had their origins in the serendipitous discovery of certain plants and their extracts being applied for the relief of pain, fever and inflammation. When salicylates were discovered in the mid-19th century to be the active components of Willow Spp., this enabled these compounds to be synthesized and from this, acetyl-salicylic acid or Aspirin was developed. Likewise, the chemical advances of the 19th-20th centuries lead to development of the non-steroidal anti-inflammatory drugs (NSAIDs), most of which were initially organic acids, but later non-acidic compounds were discovered. There were two periods of NSAID drug discovery post-World War 2, the period up to the 1970's which was the pre-prostaglandin period and thereafter up to the latter part of the last century in which their effects on prostaglandin production formed part of the screening in the drug-discovery process. Those drugs developed up to the 1980-late 90's were largely discovered empirically following screening for anti-inflammatory, analgesic and antipyretic activities in laboratory animal models. Some were successfully developed that showed low incidence of gastro-intestinal (GI) side effects (the principal adverse reaction seen with NSAIDs) than seen with their predecessors (e.g. aspirin, indomethacin, phenylbutazone); the GI reactions being detected and screened out in animal assays. In the 1990's an important discovery was made from elegant molecular and cellular biological studies that there are two cyclo-oxygenase (COX) enzyme systems controlling the production of prostanoids [prostaglandins (PGs) and thromboxane (TxA2)]; COX-1 that produces PGs and TxA2 that regulate gastrointestinal, renal, vascular and other physiological functions, and COX-2 that regulates production of PGs involved in inflammation, pain and fever. The stage was set in the 1990's for the discovery and development of drugs to selectively control COX-2 and spare the COX-1 that is central to physiological processes whose inhibition was considered a major factor in development of adverse reactions, including those in the GI tract. At the turn of this century, there was enormous commercial development following the introduction of two new highly selective COX-2 inhibitors, known as coxibs (celecoxib and rofecoxib) which were claimed to have low GI side effects. While found to have fulfilled these aims in part, an alarming turn of events took place in the late 2004 period when rofecoxib was withdrawn worldwide because of serious cardiovascular events and other coxibs were subsequently suspected to have this adverse reaction, although to a varying degree. Major efforts are currently underway to discover why cardiovascular reactions took place with coxibs, identify safer coxibs, as well as elucidate the roles of COX-2 and COX-1 in cardiovascular diseases and stroke in the hope that there may be some basis for developing newer agents (e.g. nitric oxide-donating NSAIDs) to control these conditions. The discovery of the COX isoforms led to establishing their importance in many non-arthritic or non-pain states where there is an inflammatory component to pathogenesis, including cancer, Alzheimer's and other neurodegenerative diseases. The applications of NSAIDs and the coxibs in the prevention and treatment of these conditions as well as aspirin and other analogues in the prevention of thrombo-embolic diseases now constitute one of the major therapeutic developments of the this century. Moreover, new anti-inflammatory drugs are being discovered and developed based on their effects on signal transduction and as anti-cytokine agents and these drugs are now being heralded as the new therapies to control those diseases where cytokines and other nonprostaglandin components of chronic inflammatory and neurodegenerative diseases are manifest. To a lesser extent safer application of corticosteroids and the applications of novel drug delivery systems for use with these drugs as well as with NSAIDs also represent newer technological developments of the 21st century. What started out as drugs to control inflammation, pain and fever in the last two centuries now has exploded to reveal an enormous range and type of anti-inflammatory agents and discovery of new therapeutic targets to treat a whole range of conditions that were never hitherto envisaged.

Role of poly(ADP-ribose) polymerase 1 (PARP-1) in cardiovascular diseases: the therapeutic potential of PARP inhibitors

Accumulating evidence suggests that the reactive oxygen and nitrogen species are generated in cardiomyocytes and endothelial cells during myocardial ischemia/reperfusion injury, various forms of heart failure or cardiomyopathies, circulatory shock, cardiovascular aging, diabetic complications, myocardial hypertrophy, atherosclerosis, and vascular remodeling following injury. These reactive species induce oxidative DNA damage and consequent activation of the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP-1), the most abundant isoform of the PARP enzyme family. PARP overactivation, on the one hand, depletes its substrate, NAD+, slowing the rate of glycolysis, electron transport, and ATP formation, eventually leading to the functional impairment or death of the endothelial cells and cardiomyocytes. On the other hand, PARP activation modulates important inflammatory pathways, and PARP-1 activity can also be modulated by several endogenous factors such as various kinases, purines, vitamin D, thyroid hormones, polyamines, and estrogens, just to mention a few. Recent studies have demonstrated that pharmacological inhibition of PARP provides significant benefits in animal models of cardiovascular disorders, and novel PARP inhibitors have entered clinical development for various cardiovascular indications. Because PARP inhibitors can enhance the effect of anticancer drugs and decrease angiogenesis, their therapeutic potential is also being explored for cancer treatment. This review discusses the therapeutic effects of PARP inhibitors in myocardial ischemia/reperfusion injury, various forms of heart failure, cardiomyopathies, circulatory shock, cardiovascular aging, diabetic cardiovascular complications, myocardial hypertrophy, atherosclerosis, vascular remodeling following injury, angiogenesis, and also summarizes our knowledge obtained from the use of PARP-1 knockout mice in the various preclinical models of cardiovascular diseases.