Serum γ-glutamyltransferase activity in patients with nonvalvular atrial fibrillation

Procoagulant and prothrombotic states in patients with chronic atrial fibrillation (AF) are higher than those in patients with normal sinus rhythm. We assessed and compared serum γ-glutamyltranferase (GGT) activity in elderly patients with nonvalvular AF and control participants with normal sinus rhythm. Consecutive patients (n = 81) with nonvalvular chronic AF and 210 age- and gender-matched control participants with normal sinus rhythm were retrospectively included in the study from the outpatient cardiology clinic. Presence of coronary artery disease, hypertension, gender, hyperlipidemia, diabetes mellitus, smoking status, glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and ejection fraction were comparable between the 2 groups (P > .05 for all). However, serum γ-GGT activity was significantly higher (P = .003) in patients with AF compared with those without AF. We have shown that serum γ-GGT activity is independently associated with chronic nonvalvular AF.

Critical reevaluation of endothelial progenitor cell phenotypes for therapeutic and diagnostic use

Diverse subsets of endothelial progenitor cells (EPCs) are used for the treatment of ischemic diseases in clinical trials, and circulating EPCs levels are considered as biomarkers for coronary and peripheral artery disease. However, despite significant steps forward in defining their potential for both therapeutic and diagnostic purposes, further progress has been mired by unresolved questions around the definition and the mechanism of action of EPCs. Diverse culturing methods and detection of various combinations of different surface antigens were used to enrich and identify EPCs. These attempts were particularly challenged by the close relationship and overlapping markers of the endothelial and hematopoietic lineages. This article will critically review the most commonly used protocols to define EPCs by culture assays or by fluorescence-activated cell sorter in the context of their therapeutic or diagnostic use. We also delineate new research avenues to move forward our knowledge on EPC biology.

Novel phytonutrient contributors to antioxidant protection against cardiovascular disease

The associations linking endothelial inflammation, endothelial oxidative stress, and atherogenesis and the potential for dietary phytonutrients to decrease the impact of these associations were assessed. A detailed literature review was conducted and summarized. A large body of scientific evidence describes the interactions among endothelial inflammation, endothelial oxidative stress, and atherogenesis. A growing body of research indicates that several dietary phytonutrients (astaxanthin, lycopene, lutein, and glabridin) can decrease the risk for atherosclerosis by decreasing endothelial inflammation and oxidative stress. The consumption of foods or dietary supplements that provide astaxanthin, lycopene, lutein, and glabridin can ameliorate endothelial inflammation and oxidative stress, retard atherogenesis, and decrease the risk for atherogenic cardiovascular disease.

Monomeric C-reactive protein alters fibrin clot properties on endothelial cells

Elevated plasma levels of C-reactive protein (CRP) are independently associated with increased risk of atherothrombosis. Several lines of evidence suggest that CRP has prothrombogenic effects on injured vessel wall(s) by enhancing tissue factor (TF) expression. Abnormal fibrin formation is correlated with increased thrombotic risk. However, the impact of localized, cell surface-driven in situ tissue factor generation by CRP on clot dynamics and fibrin architecture has not previously been evaluated. We examined the impact of native CRP and modified or monomeric CRP (mCRP) on the fibrin formation and structure in Human Umbilical Vein Endothelial Cells (HUVECs). Fibrin formation and structure were examined using laser scanning confocal microscopy. Incubation with mCRP on the cell surface had faster fibrin polymerization by the analysis of turbidimetry. Confocal microscopy of fibrin clots showed a significantly increased density in the treatment of mCRP compared with native CRP and control in the proximal versus distal relationship to the cell surface. The increased expression and activity of TF on the cell surface was observed by addition of mCRP. Blockage of tissue factor and lipid rafts significantly reduced the density of fibrin network produced by mCRP-stimulated endothelial cells. mCRP changes clot dynamics and alters fibrin architecture by enhancing TF on the endothelial cell surface. These results support the concept that elevated CRP levels may induce fibrinolytic resistance and endothelial dysfunction by altering fibrin clot structure.

A comparison of organic and inorganic nitrates/nitrites

Although both organic and inorganic nitrates/nitrites mediate their principal effects via nitric oxide, there are many important differences. Inorganic nitrate and nitrite have simple ionic structures and are produced endogenously and are present in the diet, whereas their organic counterparts are far more complex, and, with the exception of ethyl nitrite, are all medicinally synthesised products. These chemical differences underlie the differences in pharmacokinetic properties allowing for different modalities of administration, particularly of organic nitrates, due to the differences in their bioavailability and metabolic profiles. Whilst the enterosalivary circulation is a key pathway for orally ingested inorganic nitrate, preventing an abrupt effect or toxic levels of nitrite and prolonging the effects, this is not used by organic nitrates. The pharmacodynamic differences are even greater; while organic nitrates have potent acute effects causing vasodilation, inorganic nitrite's effects are more subtle and dependent on certain conditions. However, in chronic use, organic nitrates are considerably limited by the development of tolerance and endothelial dysfunction, whereas inorganic nitrate/nitrite may compensate for diminished endothelial function, and tolerance has not been reported. Also, while inorganic nitrate/nitrite has important cytoprotective effects against ischaemia-reperfusion injury, continuous use of organic nitrates may increase injury. While there are concerns that inorganic nitrate/nitrite may induce carcinogenesis, direct evidence of this in humans is lacking. While organic nitrates may continue to dominate the therapeutic arena, this may well change with the increasing recognition of their limitations, and ongoing discovery of beneficial effects and specific advantages of inorganic nitrate/nitrite.

Integrated approaches to functionally characterize novel factors in lipoprotein metabolism

PURPOSE OF REVIEW

To discuss if and how the combined analysis of large-scale datasets from multiple independent sources benefits the mapping of novel genetic elements with relevance to lipoprotein metabolism and allows for conclusions on underlying molecular mechanisms.

RECENT FINDINGS

Genome-wide association studies (GWAS) have identified numerous genomic loci associated with plasma lipid levels and cardiovascular disease. Yet, despite being highly successful in mapping novel loci the GWAS approach falls short to systematically extract functional information from genomic data. With the aim to complement GWAS for a better insight into disease mechanisms and identification of the most promising targets for drug development, a number of high-throughput functional genomics strategies have now been applied. These include computational approaches, consideration of gene-gene and gene-environment interactions, as well as unbiased gene-expression analyses in relevant tissues. For a limited number of loci, mechanistic insight has been gained through in-vitro and in-vivo studies by knockdown and overexpression of candidate genes.

SUMMARY

The integration of GWAS data with existing functional genomics strategies has contributed to ascertain the relevance of a number of novel factors for lipoprotein biology and disease. However, technologies are warranted that provide a more systematic insight into the molecular function and pathogenic relevance of promising candidate genes.

Safety and effectiveness of antithrombotic strategies in older adult patients with atrial fibrillation and non-ST elevation myocardial infarction

BACKGROUND

We aimed to study the comparative safety and effectiveness of various antithrombotic treatment strategies among older adults with non-ST elevation myocardial infarction (NSTEMI) and atrial fibrillation (AF).

METHODS

Using the CRUSADE registry linked to longitudinal Medicare claims data, we examined NSTEMI patients aged ≥ 65 years with a concomitant diagnosis of AF. Multivariable Cox analysis was used to compare risk of rehospitalization for bleeding and a major cardiac composite end point of death, readmission for myocardial infarction, or stroke, according to discharge antithrombotic strategy.

RESULTS

Among 7619 NSTEMI patients with AF, 29% were discharged on aspirin alone; 37%, on aspirin + clopidogrel; 7%, on warfarin alone; 17%, on aspirin + warfarin; and 10%, on warfarin + aspirin + clopidogrel. There was no difference in predicted stroke risk between groups. By 1 year, 12.2% of patients were rehospitalized for bleeding, and 33.1% had a major cardiac event. Relative to aspirin alone, antithrombotic intensification was associated with increased bleeding risk (aspirin + clopidogrel adjusted HR 1.22, 95% CI 1.03-1.46 and warfarin + aspirin HR 1.46, 95% CI 1.21-1.80). Patients treated with aspirin + clopidogrel + warfarin had the highest observed bleeding risk (HR 1.65, 95% CI 1.30-2.10). One-year risk of the major cardiac end point was similar between groups, although, relative to aspirin only, there was a trend toward lower risk for the warfarin + aspirin group (HR 0.88, 95% CI 0.78-1.00).

CONCLUSIONS

Older NSTEMI patients with AF are at high risk for subsequent bleeding and major cardiac events. Increased antithrombotic management was associated with increased bleeding risk. Further investigation is needed to clarify whether these risks are counterbalanced by reduced thromboembolic events in this population.

Rheumatologic emergencies in newborns, children, and adolescents

This article presents five clinical scenarios in which the initial manifestations of pediatric rheumatic diseases constitute life-threatening medical emergencies. It is intended as a problem-oriented guide for pediatricians to assist in the recognition of rheumatologic differentials in children presenting with critical illness and provides an approach to their initial investigation and management.

Heart of the matter: coronary dysfunction in metabolic syndrome

Metabolic syndrome (MetS) is a collection of risk factors including obesity, dyslipidemia, insulin resistance/impaired glucose tolerance, and/or hypertension. The incidence of obesity has reached pandemic levels, as ~20-30% of adults in most developed countries can be classified as having MetS. This increased prevalence of MetS is critical as it is associated with a two-fold elevated risk for cardiovascular disease. Although the pathophysiology underlying this increase in disease has not been clearly defined, recent evidence indicates that alterations in the control of coronary blood flow could play an important role. The purpose of this review is to highlight current understanding of the effects of MetS on regulation of coronary blood flow and to outline the potential mechanisms involved. In particular, the role of neurohumoral modulation via sympathetic α-adrenoceptors and the renin-angiotensin-aldosterone system (RAAS) are explored. Alterations in the contribution of end-effector K(+), Ca(2+), and transient receptor potential (TRP) channels are also addressed. Finally, future perspectives and potential therapeutic targeting of the microcirculation in MetS are discussed. This article is part of a Special Issue entitled "Coronary Blood Flow".

Berberine improves endothelial function by reducing endothelial microparticles-mediated oxidative stress in humans

BACKGROUND

Circulating endothelial microparticles (EMPs) lead to endothelial dysfunction by increasing oxidative stress. Berberine has a beneficial effect on endothelial function, but no data are available on the EMP-mediated oxidative stress. The present study tests the hypothesis that berberine contributes to the improvement of endothelial function in humans via inhibiting EMP-mediated oxidative stress in vascular endothelium.

METHODS

Twelve healthy subjects received a 1-month berberine therapy and eleven healthy subjects served as control. Endothelium-dependent and -independent function in the brachial artery was assessed by flow-mediated vasodilation (FMD) and sublingual nitroglyceride-mediated vasodilation (NMD). Circulating EMPs and serum malondialdehyde (MDA) were measured before and after therapy. Furthermore, in vitro human umbilical vein endothelial cells (HUVECs) were stimulated by EMPs with or without presence of anti-oxidant compound apocynin or berberine. Intracellular reactive oxygen species (ROS), nitric oxide (NO) production and NADPH oxidase 4 (Nox4) protein expressions were examined, respectively.

RESULTS

The levels of serum MDA and circulating CD31+/CD42- MPs were significantly reduced in the berberine group compared with the control group, which were associated with improvement of FMD. The EMPs in vitro facilitated ROS production and Nox4 protein expression and reduced NO synthesis in HUVECs. These alterations can be reversed by the presence of apocynin or berberine, respectively.

CONCLUSION

The present study demonstrated for the first time that EMP-induced upregulation of Nox4 expression may enhance ROS production in HUVECs. Berberine treatment contributes to the amelioration of endothelial function through a partially reducing oxidative stress of vascular endothelium induced by circulating CD31+/CD42- microparticles in humans.

Berberine attenuates doxorubicin-induced cardiotoxicity in mice

This study investigated the effects of berberine, a natural alkaloid, on doxorubicin-induced cardiotoxicity in mice. Mice were injected intraperitoneally with saline 10 ml/kg (n = 10), doxorubicin 2.5 mg/kg (n = 10), 60 mg/kg berberine 1 h before doxorubicin 2.5 mg/kg (n = 10), or 60 mg/kg berberine alone (n = 10) every other day for 14 days. Body weight, general condition and mortality were recorded over the 14-day study period. Electro cardiography was performed before the start of treatment and after 14 days and plasma lactate dehydrogenase (LDH) activity was measured after 14 days. At the end of the study period the heart was excised and examined histologically. An increase in mortality, an initial decrease in body weight, increased LDH activity, prolongation of QRS duration and increased myocardial injury were seen in the doxorubicin-treated group compared with the saline control group. These changes were significantly attenuated by pretreatment with berberine. The study suggests that berberine may have a potential protective role against doxorubicin-induced cardiotoxicity in mice.

Short-term outcomes in heart failure patients with chronic obstructive pulmonary disease in the community

AIM

To establish the short term outcomes of heart failure (HF) patients in the community who have concurrent chronic obstructive pulmonary disease (COPD).

METHODS

We evaluated 783 patients (27.2%) with left ventricular systolic dysfunction under the care of a regional nurse-led community HF team between June 2007 and June 2010 through a database analysis.

RESULTS

One hundred and one patients (12.9%) also had a diagnosis of COPD; 94% of patients were treated with loop diuretics, 83% with angiotensin converting enzyme inhibitors, 74% with β-blockers; 10.6% with bronchodilators; and 42% with aldosterone antagonists. The mean age of the patients was 77.9 ± 5.7 years; 43% were female and mean New York Heart Association class was 2.3 ± 0.6. The mean follow-up was 28.2 ± 2.9 mo. β-blocker utilization was markedly lower in patients receiving bronchodilators compared with those not taking bronchodilators (overall 21.7% vs 81%, P < 0.001). The 24-mo survival was 93% in patients with HF alone and 89% in those with both comorbidities (P = not significant). The presence of COPD was associated with increased risk of HF hospitalization [hazard ratio (HR): 1.56; 95% CI: 1.4-2.1; P < 0.001] and major adverse cardiovascular events (HR: 1.23; 95% CI: 1.03-1.75; P < 0.001).

CONCLUSION

COPD is a common comorbidity in ambulatory HF patients in the community and is a powerful predictor of worsening HF. It does not however appear to affect short-term mortality in ambulatory HF patients.

Assessment of ventricular pacing in the setting of an institutional improvement program: insights into physiological pacing

Background

Excessive ventricular pacing is known to be detrimental. The purpose of this study was to assess ventricular pacing in the setting of an institutional improvement program in order to decrease unnecessary pacing.

Method

This cross-sectional single-center study performed in a university hospital assessed 80 consecutive patients attending for a cardiac electronic device (pacemaker or cardioverter defibrillator) check. Forty percent of ventricular pacing was set as the cutoff level beyond which pacing was considered excessive.

Results

Three patients were excluded. Forty-six (59.7%) patients (group 1) had more than 40% ventricular pacing and 31 (40.3%) patients (group 2) showed ventricular pacing less than 41%. In group 1, corrective action was successful in 27 (58.7%) patients, but 19 (41.3%) continued to have ventricular pacing over 40% and were discussed accordingly. An improvement program was established at the institution in order to decrease unnecessary ventricular pacing.

Conclusion

Unnecessary ventricular pacing was encountered in many of the patients in this study, corrective actions were performed, and an institutional improvement project was set up as a consequence.

Hypoxic-ischemic injury in the developing brain: the role of reactive oxygen species originating in mitochondria

Mitochondrial dysfunction is the most fundamental mechanism of cell damage in cerebral hypoxia-ischemia and reperfusion. Mitochondrial respiratory chain (MRC) is increasingly recognized as a source for reactive oxygen species (ROS) in the postischemic tissue. Potentially, ROS originating in MRC can contribute to the reperfusion-driven oxidative stress, promoting mitochondrial membrane permeabilization. The loss of mitochondrial membranes integrity during reperfusion is considered as the major mechanism of secondary energy failure. This paper focuses on current data that support a pathogenic role of ROS originating from mitochondrial respiratory chain in the promotion of secondary energy failure and proposes potential therapeutic strategy against reperfusion-driven oxidative stress following hypoxia-ischemia-reperfusion injury of the developing brain.

The successful introduction of an adapted form of the mini extra corporeal circulation used for cardiac surgery in an obese patient

Obese patients undergoing cardiac surgery have been shown to have a high risk of developing postoperative complications, specifically: increased length of hospital stay, readmission to intensive care unit, acute renal failure, deep sternal wound infections and new onset of atrial fibrillation.A custom-made circuit was created to allow the use of Mini Extra Corporeal Circulation (MECC) but permitting the switch to a closed siphon drainage system in the case of difficulties.To limit artificial surface contact a small oxygenating device (Admiral, Eurosets) was employed in spite of the patients size. This adapted circuit permits a feasible and safer approach to using MECC. This report suggests that smaller oxygenators could be integrated into clinical practice in an adult MECC configuration, even for more obese patients, limiting artificial surface contact.

Therapeutic Potential of Moringa oleifera Leaves in Chronic Hyperglycemia and Dyslipidemia: A Review

Moringa oleifera (M. oleifera) is an angiosperm plant, native of the Indian subcontinent, where its various parts have been utilized throughout history as food and medicine. It is now cultivated in all tropical and sub-tropical regions of the world. The nutritional, prophylactic, and therapeutic virtues of this plant are being extolled on the Internet. Dietary consumption of its part is therein promoted as a strategy of personal health preservation and self-medication in various diseases. The enthusiasm for the health benefits of M. oleifera is in dire contrast with the scarcity of strong experimental and clinical evidence supporting them. Fortunately, the chasm is slowly being filled. In this article, I review current scientific data on the corrective potential of M. oleifera leaves in chronic hyperglycemia and dyslipidemia, as symptoms of diabetes and cardiovascular disease (CVD) risk. Reported studies in experimental animals and humans, although limited in number and variable in design, seem concordant in their support for this potential. However, before M. oleifera leaf formulations can be recommended as medication in the prevention or treatment of diabetes and CVD, it is necessary that the scientific basis of their efficacy, the therapeutic modalities of their administration and their possible side effects be more rigorously determined.

Does vitamin D protect against DNA damage?

Vitamin D is a secosteroid best known for its role in maintaining bone and muscle health. Adequate levels of vitamin D may also be beneficial in maintaining DNA integrity. This role of vitamin D can be divided into a primary function that prevents damage from DNA and a secondary function that regulates the growth rate of cells. The potential for vitamin D to reduce oxidative damage to DNA in a human has been suggested by clinical trial where vitamin D supplementation reduced 8-hydroxy-2'-deoxyguanosine, a marker of oxidative damage, in colorectal epithelial crypt cells. Studies in animal models and in different cell types have also shown marked reduction in oxidative stress damage and chromosomal aberrations, prevention of telomere shortening and inhibition of telomerase activity following treatment with vitamin D. The secondary function of vitamin D in preventing DNA damage includes regulation of the poly-ADP-ribose polymerase activity in the DNA damage response pathway involved in the detection of DNA lesions. It is also able to regulate the cell cycle to prevent the propagation of damaged DNA, and to regulate apoptosis to promote cell death. Vitamin D may contribute to prevention of human colorectal cancer, though there is little evidence to suggest that prevention of DNA damage mediates this effect, if real. Very limited human data mean that the intake of vitamin D required to minimise DNA damage remains uncertain.

Adipose tissue in the pathophysiology of cardiovascular disease: Who is guilty?

Epidemiological evidence has shown how abdominal obesity is closely associated with the development of cardiovascular disease. It has been demonstrated that patients with extensive adipose tissue usually have other concomitant cardiovascular risk factors, such insulin resistance, hypertension and dyslipidemia. Moreover, obese patients have a significantly higher risk of developing thrombophilic events compared with the non-obese. Thus, obesity is actually considered an independent cardiovascular risk factor. The pathophysiological mechanisms responsible for the association between obesity and cardiovascular disease remain largely unknown. However, it has been postulated that obese patients have an “inflammatory milieu” responsible for their metabolic disorders and vascular disease. In this context, adipocyte-derived molecules with inflammatory activity might play a pivotal role in the development of these mechanisms. In the present report, we provide an updated overview on the molecules produced by adipose tissue that are potentially involved in cardiovascular pathophysiology.

Designing a comprehensive strategy to improve one core measure: discharge of patients with myocardial infarction or heart failure on ACE inhibitors/ARBs

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ACEs/ARBs) have proven benefit for patients with myocardial infarction and heart failure; their use is a core measure of hospital quality for the Centers for Medicare and Medicaid Services. The authors' urban medical center has lower-than-average performance on this measure. The authors used published best practices to design and implement a comprehensive strategy to improve ACE/ARB performance with existing decision support and human resources. Chart reminders were targeted to providers of patients eligible for ACEs/ARBs but not receiving them. ACE/ARB performance increased 8.5% in postintervention patients compared with historical controls. The increase was 20.7% among patients not on ACEs/ARBs on admission (P =.03). Chronic kidney disease (CKD) was inversely associated with the effectiveness of the intervention. A comprehensive strategy can be effective in narrowing the performance gap even for populations with a high prevalence of CKD. However, future work is needed to improve performance among patients whose ACEs/ARBs are withheld during hospitalization.

Challenges for heart disease stem cell therapy

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. The use of stem cells to improve recovery of the injured heart after myocardial infarction (MI) is an important emerging therapeutic strategy. However, recent reviews of clinical trials of stem cell therapy for MI and ischemic heart disease recovery report that less than half of the trials found only small improvements in cardiac function. In clinical trials, bone marrow, peripheral blood, or umbilical cord blood cells were used as the source of stem cells delivered by intracoronary infusion. Some trials administered only a stem cell mobilizing agent that recruits endogenous sources of stem cells. Important challenges to improve the effectiveness of stem cell therapy for CVD include: (1) improved identification, recruitment, and expansion of autologous stem cells; (2) identification of mobilizing and homing agents that increase recruitment; and (3) development of strategies to improve stem cell survival and engraftment of both endogenous and exogenous sources of stem cells. This review is an overview of stem cell therapy for CVD and discusses the challenges these three areas present for maximum optimization of the efficacy of stem cell therapy for heart disease, and new strategies in progress.

Use of a miniaturized cardiopulmonary bypass circuit in neonates and infants is associated with fewer blood product transfusions

Miniaturized bypass circuits, including the Kids D100 oxygenator and the D130 arterial filter, were specially designed to reduce blood transfusions in small infants undergoing cardiac surgery. This study compared the number of blood product transfusions and short-term outcome between patients younger than 1 year undergoing cardiac surgery with a conventional and a miniaturized bypass circuit, after controlling for baseline characteristics and surgical complexity by 1:1 matching. Adjusted odds ratios (ORs) and 95% confidence intervals for exposure to transfusions and to any additional transfusion were estimated from binary and polytomous regression models. Of the 804 patients enrolled retrospectively, 246 were analyzed after matching. The use of the miniaturized circuit required a lower priming volume, 265.5 vs. 432.4 mL, p < 0.001, fewer packed red blood cell (PRBC) transfusions, 1.4 vs. 2.0 U, p < 0.001, and fewer platelet transfusions on the day of surgery, 57.7% vs. 76.4%, p < 0.001. After adjustment for the use of antifibrinolytics, the ultrafiltration rate, and the year of surgery, the use of the miniaturized circuit was independently related to a reduced risk of additional PRBC transfusions, OR 0.04 (0.01, 0.13), and exposure to platelet transfusions, OR 0.78 (0.63, 0.96). Short-term outcome was similar.

Why is coronary collateral growth impaired in type II diabetes and the metabolic syndrome?

Type II diabetes and the metabolic syndrome are strong predictors of severity of occlusive coronary disease and poorer outcomes of coronary revascularization therapies. Coronary collateral growth can provide an alternative or accessory pathway of revascularization. However, collateral growth is impaired in type II diabetes and the metabolic syndrome. Although many factors necessary for collateral growth are known and many interventions have shown promising results in animal studies, not a single attempt to induce coronary collateral growth in human clinical trials has led to satisfactory results. Accordingly, the first part of this review outlines the known deleterious effects of diabetes and the metabolic syndrome on factors necessary for collateral growth, including pro-angiogenic growth factors, endothelial function, the redox state of the coronary circulation, intracellular signaling, leukocytes and bone marrow-derived progenitors cells. The second section highlights the gaps in our current knowledge of how these factors interact with the radically altered environment of the coronary circulation in diabetes and the metabolic syndrome. The interplay between these pathologies and inadequately explored areas related to the temporal regulation of collateral remodeling and the roles of the extracellular matrix, vascular cell phenotype and pro-inflammatory cytokines are emphasized with implications to development of efficient therapies.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

Obesity and risk of vascular disease: importance of endothelium-dependent vasoconstriction

Obesity has become a serious global health issue affecting both adults and children. Recent devolopments in world demographics and declining health status of the world's population indicate that the prevalence of obesity will continue to increase in the next decades. As a disease, obesity has deleterious effects on metabolic homeostasis, and affects numerous organ systems including heart, kidney and the vascular system. Thus, obesity is now regarded as an independent risk factor for atherosclerosis-related diseases such as coronary artery disease, myocardial infarction and stroke. In the arterial system, endothelial cells are both the source and target of factors contributing to atherosclerosis. Endothelial vasoactive factors regulate vascular homeostasis under physiological conditions and maintain basal vascular tone. Obesity results in an imbalance between endothelium-derived vasoactive factors favouring vasoconstriction, cell growth and inflammatory activation. Abnormal regulation of these factors due to endothelial cell dysfunction is both a consequence and a cause of vascular disease processes. Finally, because of the similarities of the vascular pathomechanisms activated, obesity can be considered to cause accelerated, 'premature' vascular aging. Here, we will review some of the pathomechanisms involved in obesity-related activation of endothelium-dependent vasoconstriction, the clinical relevance of obesity-associated vascular risk, and therapeutic interventions using 'endothelial therapy' aiming at maintaining or restoring vascular endothelial health.

LINKED ARTICLES

This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.

Clinical and prognostic implications of atrial fibrillation in patients undergoing transcatheter aortic valve implantation

AIM

To study a cohort of consecutive patients undergoing transcatheter aortic valve implantation (TAVI) and compare the outcomes of atrial fibrillation (AF) patients vs patients in sinus rhythm (SR).

METHODS

All consecutive patients undergoing TAVI in our hospital were included. The AF group comprised patients in AF at the time of TAVI or with history of AF, and were compared with the SR group. Procedural, echocardiographic and follow-up variables were compared. Likewise, the CHA(2)DS(2)-VASC stroke risk score and HAS-BLED bleeding risk score and antithrombotic treatment at discharge in AF patients were compared with that in SR patients.

RESULTS

From a total of 34 patients undergoing TAVI, 17 (50%) were allocated to the AF group, of whom 15 (88%) were under chronic oral anticoagulation. Patients in the AF group were similar to those in the SR group except for a trend (P = 0.07) for a higher logistic EuroSCORE (28% vs 19%), and a higher prevalence of hypertension (82% vs 53%) and chronic renal failure (17% vs 0%). Risk of both stroke and bleeding was high in the AF group (mean CHA(2)DS(2)-VASC 4.3, mean HAS-BLED 2.9). In the AF group, treatment at discharge included chronic oral anticoagulation in all except one case, and in association with an antiplatelet drug in 57% of patients. During a mean follow-up of 11 mo (maximum 32), there were only two strokes, none of them during the peri-procedural period: one in the AF group at 30 mo and one in the SR group at 3 mo. There were no statistical differences in procedural success, and clinical outcome (survival at 1 year 81% vs 74% in AF and SR groups, respectively, P = NS).

CONCLUSION

Patients in AF undergoing TAVI show a trend to a higher surgical risk. However, in our cohort, patients in AF did not have a higher stroke rate compared to the SR group, and the prognosis was similar in both groups.

Prognostic significance of heart rate in hospitalized patients presenting with myocardial infarction

AIM

To investigate the prognostic significance of resting heart rate in patients with acute coronary syndrome (ACS), independent of other known factors.

METHODS

Patients 40 years of age or older who had been admitted with acute coronary syndrome (ACS) to one of the 94 hospitals participating in the Prevalence of Peripheral Arterial Disease in Patients with Acute Coronary Syndrome (PAMISCA) study were included. Patients were divided into two groups based on their resting heart rate (HR ≥ or < 70 bpm). Complications were recording during a follow-up period of 1 year.

RESULTS

There were 1054 ACS patients analyzed (43.5% with ST segment elevation and 56.5% without elevation). Mean age was 66.6 ± 11.7 years, 70.6% were male and 29.4% of subjects were female. During follow-up, more patients in the HR ≥ 70 bpm group were hospitalized for heart failure and they also had a higher mortality rate. In the multivariate analysis, a heart rate of ≥ 70 bpm was independently related to overall mortality during the follow-up period (hazard ratio 2.5; 95% confidence interval, 1.26-4.97, P = 0.009).

CONCLUSION

A resting heart rate ≥ 70 bpm in patients who survive an ACS is an indicator of a high risk of suffering cardiovascular events during follow-up.

Insulin resistance: Is it time for primary prevention?

Insulin resistance is a clinical condition characterized by a decrease in sensitivity and responsiveness to the metabolic actions of insulin, so that a given concentration of insulin produces a less-than-expected biological effect. As a result, higher levels of insulin are needed to maintain normal glucose tolerance. Hyperinsulinemia, indeed, is one of the principal characteristics of insulin resistance states. This feature is common in several pathologic conditions, such as type 2 diabetes, obesity, and dyslipidemia, and it is also a prominent component of hypertension, coronary heart disease, and atherosclerosis. The presence of endothelial dysfunction, related to insulin resistance, plays a key role in the development and progression of atherosclerosis in all of these disorders. Insulin resistance represents the earliest detectable abnormality in type 2 diabetes, and is one of the major underlying mechanisms of hypertension and cardiovascular diseases. Its early detection could be of great importance, in order to set a therapeutic attack and to counteract the higher risk of diabetes and cardiovascular diseases.

Aspirin suppresses cardiac fibroblast proliferation and collagen formation through downregulation of angiotensin type 1 receptor transcription

Aspirin (acetyl salicylic acid, ASA) is a common drug used for its analgesic and antipyretic effects. Recent studies show that ASA not only blocks cyclooxygenase, but also inhibits NADPH oxidase and resultant reactive oxygen species (ROS) generation, a pathway that underlies pathogenesis of several ailments, including hypertension and tissue remodeling after injury. In these disease states, angiotensin II (Ang II) activates NADPH oxidase via its type 1 receptor (AT1R) and leads to fibroblast growth and collagen synthesis. In this study, we examined if ASA would inhibit NADPH oxidase activation, upregulation of AT1R transcription, and subsequent collagen generation in mouse cardiac fibroblasts challenged with Ang II. Mouse heart fibroblasts were isolated and treated with Ang II with or without ASA. As expected, Ang II induced AT1R expression, and stimulated cardiac fibroblast growth and collagen synthesis. The AT1R blocker losartan attenuated these effects of Ang II. Similarly to losartan, ASA, and its SA moiety suppressed Ang II-mediated AT1R transcription and fibroblast proliferation as well as expression of collagens and MMPs. ASA also suppressed the expression of NADPH oxidase subunits (p22(phox), p47(phox), p67(phox), NOX2 and NOX4) and ROS generation. ASA did not affect total NF-κB p65, but inhibited its phosphorylation and activation. These observations suggest that ASA inhibits Ang II-induced NADPH oxidase expression, NF-κB activation and AT1R transcription in cardiac fibroblasts, and fibroblast proliferation and collagen expression. The critical role of NADPH oxidase activity in stimulation of AT1R transcription became apparent in experiments where ASA also inhibited AT1R transcription in cardiac fibroblasts challenged with H2O2. Since SA had similar effect as ASA on AT1R expression, we suggest that ASA's effect is mediated by its SA moiety.

The contribution of oxidative stress to drug-induced organ toxicity and its detection in vitro and in vivo

INTRODUCTION

Nowadays the 'redox hypothesis' is based on the fact that thiol/disulfide couples such as glutathione (GSH/GSSG), cysteine (Cys/CySS) and thioredoxin ((Trx-(SH)2/Trx-SS)) are functionally organized in redox circuits controlled by glutathione pools, thioredoxins and other control nodes, and they are not in equilibrium relative to each other. Although ROS can be important intermediates of cellular signaling pathways, disturbances in the normal cellular redox can result in widespread damage to several cell components. Moreover, oxidative stress has been linked to a variety of age-related diseases. In recent years, oxidative stress has also been identified to contribute to drug-induced liver, heart, renal and brain toxicity.

AREAS COVERED

This review provides an overview of current in vitro and in vivo methods that can be deployed throughout the drug discovery process. In addition, animal models and noninvasive biomarkers are described.

EXPERT OPINION

Reducing post-market drug withdrawals is essential for all pharmaceutical companies in a time of increased patient welfare and tight budgets. Predictive screens positioned early in the drug discovery process will help to reduce such liabilities. Although new and more efficient assays and models are being developed, the hunt for biomarkers and noninvasive techniques is still in progress.

Marine carotenoids and oxidative stress

Oxidative stress induced by reactive oxygen species plays an important role in the etiology of many diseases. Dietary phytochemical products, such as bioactive food components and marine carotenoids (asthaxantin, lutein, β-carotene, fucoxanthin), have shown an antioxidant effect in reducing oxidative markers stress. Scientific evidence supports the beneficial role of phytochemicals in the prevention of some chronic diseases. Many carotenoids with high antioxidant properties have shown a reduction in disease risk both in epidemiological studies and supplementation human trials. However, controlled clinical trials and dietary intervention studies using well-defined subjects population have not provided clear evidence of these substances in the prevention of diseases. The most important aspects of this special issue will cover the synthesis, biological activities, and clinical applications of marine carotenoids, with particular attention to recent evidence regarding anti-oxidant and anti-inflammatory properties in the prevention of cardiovascular disease.

Increased leukocyte Rho-associated coiled-coil containing protein kinase activity predicts the presence and severity of coronary vasospastic angina

OBJECTIVE

Although inhibition of Rho-associated coiled-coil containing protein kinase (ROCK) has been shown to prevent coronary vasospastic angina (CVA), direct evidence linking ROCK activity and CVA is lacking. Accordingly, we investigated whether ROCK activity is an independent marker for CVA and is altered after treatment with antispastic medications.

METHODS AND RESULTS

We prospectively studied 31 Taiwanese patients who were diagnosed with CVA and 33 control subjects. Subject demographics were recorded, and blood samples were obtained at baseline in all participants and in CVA patients after 3 months of antispastic treatment. Compared with control subjects, leukocyte ROCK activity was greater in CVA patients (136% versus 91%, P<0.001). A cutoff value for leukocyte ROCK activity of 104% predicted the presence of CVA with specificity and sensitivity rates of 88% and 84%, respectively. ROCK activity increased with the severity of CVA (P for trend<0.001). Following 3-month treatment of antispastic agents, leukocyte ROCK activity, high-sensitivity C-reactive protein, and interleukin-6 levels were reduced by 43%, 42% and 27%, respectively (P<0.05 for all).

CONCLUSIONS

Increased levels of leukocyte ROCK activity independently predicted the presence of CVA and correlated with CVA severity. Treatment with antispastic agents substantially reduced the level of leukocyte ROCK activity.

Involvement of upper torso stress amplification, tissue compression and distortion in the pathogenesis of keloids

Keloids are benign tumours composed of fibrous tissue produced during excessive tissue repair triggered by minor injury, trauma or surgical incision. Although it is recognized that keloids have a propensity to form in the upper torso of the body, the predisposing factors responsible for this have not been investigated. It is crucial that the aetiopathoical factors implicated in keloid formation be established to provide guidelines for well-informed more successful treatment. We compared keloid-prone and keloid-protected skin, identified pertinent morphological differences and explored how inherent structural characteristics and intrinsic factors may promote keloid formation. It was determined that keloid prone areas were covered with high tension skin that had low stretch and a low elastic modulus when compared with skin in keloid protected areas where the skin was lax with a high elastic modulus and low pre-stress level. Factors contributing to elevated internal stress in keloid susceptible skin were the protrusion of hard connective tissue such as bony prominences or cartilage into the dermis of skin as well as inherent skin characteristics such as the bundled arrangement of collagen in the reticular dermis, the existent high tension, the low elastic modulus, low stretch ability, contractile forces exerted by wound healing fibroblastic cells and external forces. Stress promotes keloid formation by causing dermal distortion and compression which subsequently stimulate proliferation and enhanced protein synthesis in wound healing fibroblastic cells. The strain caused by stress also compresses and occludes microvessels causing ischaemic effects and reperfusion injury which stimulate growth when blood rich in growth factors returns to the tissue. The growth promoting effects of increased internal stress, primarily, and growth factors released by reperfusing blood, manifest in keloid formation. Other inherent skin characteristics promoting keloid growth during the late stages of wound healing in the upper torso are the thinner epidermis, the presence of vellus hairs, the absence of protective immunoglobulin A (IgA), and the thick fragile quality of upper torso skin. As it is not known why there is a predilection for keloids to form in the upper torso of the body, this hypothesis implicating and associating inherent morphological characteristics and elevated stress in the aetiopathogenesis of keloids is of potential value in terms of prevention, management and treatment of these enigmatic tumours.

Assessment of left atrial dysfunction in obstructive sleep apnea patients with the two dimensional speckle-tracking echocardiography

BACKGROUND

The aim of this study was to compare left atrial (LA) longutidinal myocardial function in obstructive sleep apnea (OSA) patients with healthy individuals using two-dimensional speckle-tracking echocardiography method (2D-STE).

METHOD

Twenty one healthy individuals and 58 OSA patients were included. According to the AHI (apnea hypopnea index) patients were examined in mild, moderate and severe OSA groups. Images of the LA were acquired from the apical two- and four-chamber views. LA strain(LA(S)) and strain rate(LA(SR)) parameters [systolic (S), early diastolic (E), late diastolic (A) during atrial contraction] were assessed.

RESULTS

LA(S-S), LA(SR-S), LA(S-E) and LA(SR-E) values decreased with severity of OSA. Severe OSA patients have lower LA(S-S) and LA(SR-S) values (p < 0.03). While a difference in the LA(SR-E) value between groups was significant beginning with the moderate OSA group (p < 0.03), no LA(S-E) value differences were observed between moderate and mild OSA groups (p > 0.03). LA(S-A) and LA(SR-A) values were increasing with the disease severity up to moderate OSA. LA(S-A) and LA(SR-A) values of moderate OSA were greater than the mild OSA patients and healthy individuals (p < 0.03). These were lower in severe OSA than the moderate OSA (p < 0.03), however, they were greater than the healthy individuals (p < 0.03). The AHI was found to be negatively correlated with the LA(S-S), LA(SR-S) LA(S-E), LA(SR-E), whereas AHI was not correlated with the LA(S-A), LA(SR-A) values.

CONCLUSION

LA remodeling and dysfunction that accompany OSA can be detected in the subclinical stage with a detailed evaluation of active and passive functions of the LA using the 2D-STE method.

Hypertrophic cardiomyopathy: from mutation to functional analysis of defective protein

Aim

To analyze the genesis of hypertrophic cardiomyopathy on a large cohort of patients from molecular genetics point of view and perform the functional analysis of the 3D molecular model of defective myosin-7 protein in silico.

Methods

The study enrolled 153 patients with diagnosed hypertrophic cardiomyopathy from different parts of the Czech Republic. DNA samples were analyzed for mutations in exons 21 and 22 of the MYH7 gene, which have been associated with high mutation clustering. The 3D model of human myosin-7 was built using the x-ray structure of nucleotide-free scallop myosin S1 as the structural template. We performed de novo structure prediction of mutant and wild type peptides spanning the 769-788 amino acids region of the myosin-7 protein.

Results

The Arg⁸⁷⁰His and Asp⁷⁷⁸Val amino acid alterations were found in 2 unrelated patients with a severe form of hypertrophic cardiomyopathy. The Asp⁷⁷⁸Val variation was chosen for subsequent 3D molecular modeling in silico. The mutation of the Asp by Val not only changes the character of the interaction pattern with other amino acids or ions but Val, being a small hydrophobic amino acid, can also completely change the stability of the region.

Conclusion

Mutation location in the MYH7 gene and changes in amino acid composition may have a crucial negative impact on the outcome of the disease in patients with hypertrophic cardiomyopathy. In addition, a mutation that changes the charge of the amino acid is more likely to affect protein function than a conservative mutation.

The importance of diabetes mellitus in the global epidemic of cardiovascular disease: the case of the state of Qatar

As a manifestation of the epidemiologic transition being experienced throughout the developing world, the prevalence of diabetes mellitus (DM) is increasing. However, whether an individual's risk of cardiovascular diseases as a consequence of DM is also higher in these countries is unknown. We conducted a case-control study at the medical center in the state of Qatar comparing the prevalence of DM in 512 patients who were admitted with acute myocardial infarctions (MI) and 262 cases of cerebrovascular accidents (CVA) to 382 hospital and outpatient controls to calculate the odds ratios (OR) associated with DM for MI and CVA. The OR for MI was estimated to be 4.01 compared to 2.92 for other countries in the Middle East and 1.75 for North America. The OR was even higher for Qatari natives. Understanding the reasons for this increase, including genetic differences, lifestyle, and medical management issues, is critical for the design and prioritization of effective interventions.

Myocardial infarct size and area at risk assessment in mice

Mouse models of myocardial ischemia and infarction are important in cardiovascular research. Reliable and reproducible assessment of the area at risk (AAR) and infarct size (IS) in mice is vital for deciphering mechanisms behind these common diseases, and for developing and evaluating treatment strategies. The present review will briefly describe and discuss the most common methods for determining the AAR and IS in mouse models of cardiovascular disease. Several methods exist for ex vivo assessment of IS. Conventional histological stains target the fibrous scar and require several days to pass from the time of infarct induction until the animal is euthanized, whereas triphenyltetrazolium-based techniques stain the viable tissue surrounding the infarct and can be performed on tissue harvested within a few hours after infarction. The AAR is usually stained by injecting a dye into the circulation. This dye subsequently distributes to perfused tissue but leaves the AAR unstained. In vivo assessment enables serial measurements of the IS and/or AAR and is sometimes preferable to ex vivo techniques. Echocardiography is usually the method of choice but magnetic resonance imaging-based techniques are also used. The aim of the present review was to provide basic researchers with an introduction to the various techniques used to assess and quantify the IS and AAR in experimental mouse models of myocardial ischemia-reperfusion and infarction.

Fatty Acid Oxidation and Cardiovascular Risk during Menopause: A Mitochondrial Connection?

Menopause is a consequence of the normal aging process in women. This fact implies that the physiological and biochemical alterations resulting from menopause often blur with those from the aging process. It is thought that menopause in women presents a higher risk for cardiovascular disease although the precise mechanism is still under discussion. The postmenopause lipid profile is clearly altered, which can present a risk factor for cardiovascular disease. Due to the role of mitochondria in fatty acid oxidation, alterations of the lipid profile in the menopausal women will also influence mitochondrial fatty acid oxidation fluxes in several organs. In this paper, we propose that alterations of mitochondrial bioenergetics in the heart, consequence from normal aging and/or from the menopausal process, result in decreased fatty acid oxidation and accumulation of fatty acid intermediates in the cardiomyocyte cytosol, resulting in lipotoxicity and increasing the cardiovascular risk in the menopausal women.

Cell biology of ischemia/reperfusion injury

Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.

Pneumococcal Pyopericardium Masquerading as Acute Coronary Syndrome

A 54-year-old man was admitted with a one-week history of chest pain, increasing in severity and worsening dyspnoea. An ECG revealed changes consistent with an acute coronary syndrome (ACS) and a chest X-ray showed an enlarged cardiac shadow. Following admission to the coronary care unit for treatment of presumed ACS his condition deteriorated. A diagnosis of sepsis was made. A CT scan revealed a large pericardial and bilateral pleural effusions. Heart sounds were muffled and neck veins distended, suggesting pericardial tamponade. Echocardiography showed a global pericardial effusion ranging from 2–4 cm with haemodynamic compromise. Sub-xiphisternal pericardiocentesis revealed frank pus from the pericardial cavity and a total of 1,000 mL drained over 48 hours. Rapid haemodynamic improvement ensued. Streptococcus pneumoniae was isolated and the patient was successfully treated with intravenous antibiotics with no requirement for pericardial surgery. In the developed world acute purulent pericarditis is a rare entity with a high mortality rate. Only 10–20% of cases are diagnosed ante-mortem. The condition requires prompt recognition and immediate intervention. The diagnostic picture in this case was initially clouded by the suspicion of ischaemic coronary disease as well as the presence of sepsis. The presentation, management and risk factors associated with this unusual condition are discussed.