Arrhythmogenic effect of sympathetic histamine in mouse hearts subjected to acute ischemia

Effect of Histamine H2 Receptor Antagonists on All-Cause Mortality in Critically Ill Patients With Essential Hypertension: A Retrospective Cohort Study

Previous studies found that histamine H2 receptor antagonists (H2RAs) had blood pressure lowering and cardioprotective effects, but the impact of H2RAs on the survival outcomes of critically ill patients with essential hypertension is still unclear. The aim of this study was to investigate the association of H2RAs exposure with all-cause mortality in patients with essential hypertension based on Medical Information Mart for Intensive Care III database. A total of 17,739 patients were included, involving 8482 H2RAs users and 9257 non-H2RAs users. Propensity score matching (PSM) was performed to improve balance between 2 groups that were exposed to H2RAs or not. Kaplan-Meier survival curves were used to compare the cumulative survival rates and multivariable Cox regression models were performed to evaluate the association between H2RAs exposure and all-cause mortality. After 1:1 PSM, 4416 pairs of patients were enrolled. The results revealed potentially significant association between H2RAs exposure and decreased 30-day, 90-day, and 1-year mortalities in multivariate analyses (HR = 0.783, 95% CI: 0.696-0.882 for 30-day; HR = 0.860, 95% CI: 0.778-0.950 for 90-day; and HR = 0.883, 95% CI: 0.811-0.961 for 1-year mortality, respectively). Covariate effect analyses showed that the use of H2RAs was more beneficial in essential hypertension patients with age ≥ 60, BMI ≥ 25 kg/m2, coronary arteriosclerosis, stroke, and acute kidney failure, respectively. In conclusion, H2RAs exposure was related to lower mortalities in critically ill patients with essential hypertension, which provided novel potential strategy for the use of H2RAs in essential hypertension patients.

Health position paper and redox perspectives - Disease burden by transportation noise

Transportation noise is a ubiquitous urban exposure. In 2018, the World Health Organization concluded that chronic exposure to road traffic noise is a risk factor for ischemic heart disease. In contrast, they concluded that the quality of evidence for a link to other diseases was very low to moderate. Since then, several studies on the impact of noise on various diseases have been published. Also, studies investigating the mechanistic pathways underlying noise-induced health effects are emerging. We review the current evidence regarding effects of noise on health and the related disease-mechanisms. Several high-quality cohort studies consistently found road traffic noise to be associated with a higher risk of ischemic heart disease, heart failure, diabetes, and all-cause mortality. Furthermore, recent studies have indicated that road traffic and railway noise may increase the risk of diseases not commonly investigated in an environmental noise context, including breast cancer, dementia, and tinnitus. The harmful effects of noise are related to activation of a physiological stress response and nighttime sleep disturbance. Oxidative stress and inflammation downstream of stress hormone signaling and dysregulated circadian rhythms are identified as major disease-relevant pathomechanistic drivers. We discuss the role of reactive oxygen species and present results from antioxidant interventions. Lastly, we provide an overview of oxidative stress markers and adverse redox processes reported for noise-exposed animals and humans. This position paper summarizes all available epidemiological, clinical, and preclinical evidence of transportation noise as an important environmental risk factor for public health and discusses its implications on the population level.

Histamine H2 receptor antagonist exhibited comparable all-cause mortality-decreasing effect as β-blockers in critically ill patients with heart failure: a cohort study

Background: Our previous study reported that histamine H2 receptor antagonists (H2RAs) exposure was associated with decreased mortality in critically ill patients with heart failure (HF) through the same pharmacological mechanism as β-blockers. However, population-based clinical study directly comparing the efficacy of H2RAs and β-blockers on mortality of HF patients are still lacking. This study aims to compare the association difference of H2RAs and β-blockers on mortality in critically ill patients with HF using the Medical Information Mart for Intensive Care III database (MIMIC-III). Methods: Study population was divided into 4 groups: β-blockers + H2RAs group, β-blockers group, H2RAs group, and Non-β-blockers + Non-H2RAs group. Kaplan-Meier curves and multivariable Cox regression models were employed to evaluate the differences of all-cause mortalities among the 4 groups. Propensity score matching (PSM) was used to increase comparability of four groups. Results: A total of 5593 patients were included. After PSM, multivariate analyses showed that patients in H2RAs group had close all-cause mortality with patients in β-blockers group. Furthermore, 30-day, 1-year, 5-year and 10-year all-mortality of patients in β-blockers + H2RAs group were significantly lower than those of patients in β-blockers group, respectively (HR: 0.64, 95%CI: 0.50-0.82 for 30-day; HR: 0.80, 95%CI: 0.69-0.93 for 1-year mortality; HR: 0.83, 95%CI: 0.74-0.93 for 5-year mortality; and HR: 0.85, 95%CI: 0.76-0.94 for 10-year mortality, respectively). Conclusion: H2RAs exposure exhibited comparable all-cause mortality-decreasing effect as β-blockers; and, furthermore, H2RAs and β-blockers had additive or synergistic interactions to improve survival in critically ill patients with HF.

Importance of Mitochondria in Cardiac Pathologies: Focus on Uncoupling Proteins and Monoamine Oxidases

On the one hand, reactive oxygen species (ROS) are involved in the onset and progression of a wide array of diseases. On the other hand, these are a part of signaling pathways related to cell metabolism, growth and survival. While ROS are produced at various cellular sites, in cardiomyocytes the largest amount of ROS is generated by mitochondria. Apart from the electron transport chain and various other proteins, uncoupling protein (UCP) and monoamine oxidases (MAO) have been proposed to modify mitochondrial ROS formation. Here, we review the recent information on UCP and MAO in cardiac injuries induced by ischemia-reperfusion (I/R) as well as protection from I/R and heart failure secondary to I/R injury or pressure overload. The current data in the literature suggest that I/R will preferentially upregulate UCP2 in cardiac tissue but not UCP3. Studies addressing the consequences of such induction are currently inconclusive because the precise function of UCP2 in cardiac tissue is not well understood, and tissue- and species-specific aspects complicate the situation. In general, UCP2 may reduce oxidative stress by mild uncoupling and both UCP2 and UCP3 affect substrate utilization in cardiac tissue, thereby modifying post-ischemic remodeling. MAOs are important for the physiological regulation of substrate concentrations. Upon increased expression and or activity of MAOs, however, the increased production of ROS and reactive aldehydes contribute to cardiac alterations such as hypertrophy, inflammation, irreversible cardiomyocyte injury, and failure.

Sex Difference in Cardioprotection against Acute Myocardial Infarction in MAO-B Knockout Mice In Vivo

The cardiomyocyte-specific knockout (KO) of monoamine oxidase (MAO)-B, an enzyme involved in the formation of reactive oxygen species (ROS), reduced myocardial ischemia/reperfusion (I/R) injury in vitro. Because sex hormones have a strong impact on MAO metabolic pathways, we analyzed the myocardial infarct size (IS) following I/R in female and male MAO-B KO mice in vivo. Method and Results: To induce the deletion of MAO-B, MAO-B KO mice (Myh6 Cre+/MAO-Bfl/fl) and wild-type (WT, Cre-negative MAO-Bfl/fl littermates) were fed with tamoxifen for 2 weeks followed by 10 weeks of normal mice chow. Myocardial infarction (assessed by TTC staining and expressed as a percentage of the area at risk as determined by Evans blue staining)) was induced by 45 min coronary occlusion followed by 120 min of reperfusion. Results: The mortality following I/R was higher in male compared to female mice, with the lowest mortality found in MAO-B KO female mice. IS was significantly higher in male WT mice compared to female WT mice. MAO-B KO reduced IS in male mice but had no further impact on IS in female MAO-B KO mice. Interestingly, there was no difference in the plasma estradiol levels among the groups. Conclusion: The cardiomyocyte-specific knockout of MAO-B protects male mice against acute myocardial infarction but had no effect on the infarct size in female mice.

Histamine H2 receptor antagonist exposure was related to decreased all-cause mortality in critical ill patients with heart failure: a cohort study

BACKGROUND

Previous studies reported that histamine H2 receptor antagonists (H2RAs) had cardioprotective effects. However, the effect of H2RAs on mortality of critical ill patients with heart failure (HF) remains unclear. The aim of this study was to clarify the association between H2RAs and all-cause mortality of critical ill patients with HF based on Medical Information Mart for Intensive Care III database (MIMIC-III).

METHODS

Propensity score matching (PSM) was applied to account for the baseline differences between two groups that exposed to H2RAs or not. The study primary outcome was all-cause mortality. Kaplan-Meier curves and multivariable Cox regression models were employed to estimate the effects of H2RAs on mortality of critical ill patients with HF.

RESULTS

A total of 10 387 patients were included, involving 4440 H2RAs users and 5947 non-H2RAs users. After matching, 3130 pairs of patients were matched between H2RAs users and non-H2RAs users. The results showed significant association between H2RAs exposure and decreased 30-day, 90-day and 1-year mortality in both univariate analyses and multivariate analyses (HR = 0.73, 95%CI: 0.65-0.83 for 30-day; HR = 0.80, 95%CI: 0.72-0.89 for 90-day; and HR = 0.83, 95%CI: 0.76-0.90 for 1-year mortality, respectively) by Cox regression after PSM. Furthermore, stratified analyses revealed that the 30-day, 90-day and 1-year mortality of ranitidine users were significantly lower than those of famotidine users, respectively.

CONCLUSIONS

H2RAs exposure was associated with lower mortality in critical ill patients with HF. Furthermore, ranitidine might be superior to famotidine in reducing mortality of critical ill patients with HF.

The Roles of Cardiovascular H2-Histamine Receptors Under Normal and Pathophysiological Conditions

This review addresses pharmacological, structural and functional relationships among H₂-histamine receptors and H₁-histamine receptors in the mammalian heart. The role of both receptors in the regulation of force and rhythm, including their electrophysiological effects on the mammalian heart, will then be discussed in context. The potential clinical role of cardiac H₂-histamine-receptors in cardiac diseases will be examined. The use of H₂-histamine receptor agonists to acutely increase the force of contraction will be discussed. Special attention will be paid to the potential role of cardiac H₂-histamine receptors in the genesis of cardiac arrhythmias. Moreover, novel findings on the putative role of H₂-histamine receptor antagonists in treating chronic heart failure in animal models and patients will be reviewed. Some limitations in our biochemical understanding of the cardiac role of H₂-histamine receptors will be discussed. Recommendations for further basic and translational research on cardiac H₂-histamine receptors will be offered. We will speculate whether new knowledge might lead to novel roles of H₂-histamine receptors in cardiac disease and whether cardiomyocyte specific H₂-histamine receptor agonists and antagonists should be developed.

Histamine receptors in heart failure

The biogenic amine, histamine, is found predominantly in mast cells, as well as specific histaminergic neurons. Histamine exerts its many and varied actions via four G-protein-coupled receptors numbered one through four. Histamine has multiple effects on cardiac physiology, mainly via the histamine 1 and 2 receptors, which on a simplified level have opposing effects on heart rate, force of contraction, and coronary vasculature function. In heart failure, the actions of the histamine receptors are complex, the histamine 1 receptor appears to have detrimental actions predominantly in the coronary vasculature, while the histamine 2 receptor mediates adverse effects on cardiac remodeling via actions on cardiomyocytes, fibroblasts, and even endothelial cells. Conversely, there is growing evidence that the histamine 3 receptor exerts protective actions when activated. Little is known about the histamine 4 receptor in heart failure. Targeting histamine receptors as a therapeutic approach for heart failure is an important area of investigation given the over-the-counter access to many compounds targeting these receptors, and thus the relatively straight forward possibility of drug repurposing. In this review, we briefly describe histamine receptor signaling and the actions of each histamine receptor in normal cardiac physiology, before describing in more detail the known role of each histamine receptor in adverse cardiac remodeling and heart failure. This includes information from both clinical studies and experimental animal models. It is the goal of this review article to bring more focus to the possibility of targeting histamine receptors as therapy for heart failure.

Human histamine H2 receptors can initiate cardiac arrhythmias in a transgenic mouse

Histamine is known to lead to arrhythmias in the human heart. A mouse model to mimic these effects has hitherto not been available but might be useful to study the mechanism(s) of H₂-histamine receptor-induced arrhythmias and may support the search for new antiarrhythmic drugs. In order to establish such a model in mice, we studied here the incidence of cardiac arrhythmias under basal and under stimulated conditions in atrial and ventricular preparations from mice that overexpressed the human H₂-histamine receptors in a cardiac-specific way (H₂-TG) in comparison with their wild-type (WT) littermate controls. We had shown before that histamine exerted concentration and time-dependent positive inotropic and positive chronotropic effects only in cardiac preparations from H₂-TG and not from WT. We noted under basal conditions (no drug addition) that right atrial preparations from H₂-TG exhibited more spontaneous arrhythmias than right atrial preparations from WT. These arrhythmias in H₂-TG could be blocked by the H₂-histamine receptor antagonist cimetidine. In a similar fashion, histamine and dimaprit (an agonist at H₂ and not H₁-histamine receptors) more often induced arrhythmias in right atrial preparations from H₂-TG than from WT. To understand better the signal transduction mechanism(s) involved in these arrhythmias, we studied partially depolarized left atrial preparations. In these preparations, a positive inotropic effect of histamine was still present in the additional presence of 44 mM potassium ions (used to block sodium channels) in H₂-TG but not WT and this positive inotropic effect could be blocked by cimetidine and this is consistent with the involvement of calcium ion channels in the contractile and thus might mediate also the arrhythmogenic effects of histamine in H₂-TG. However, compounds reported to release histamine from cells and thereby leading to arrhythmias in humans, namely morphine, ketamine, and fentanyl, failed to induce a more pronounced positive inotropic effect in atrial preparations from H₂-TG compared to WT, arguing against an involvement of histamine release in their proarrhythmic side effects in patients. Measuring left ventricular contractility in isolated retrogradely perfused hearts (Langendorff mode), we detected under basal conditions (no drug application) more spontaneous arrhythmias in hearts from H₂-TG than from WT. In summary, we noted that overexpression of human H₂-histamine receptors in a novel transgenic animal model can lead to arrhythmias. We suggest that this model might be useful to understand the mechanism(s) of histamine-induced cardiac arrhythmias in humans better in a molecular way and may be of value to screen novel antiarrhythmic drugs.

Vegetal diamine oxidase alleviates histamine-induced contraction of colonic muscles

Excess of histamine in gut lumen generates a pronounced gastrointestinal discomfort, which may include diarrhea and peristalsis dysfunctions. Deleterious effects of histamine can be alleviated with antihistamine drugs targeting histamine receptors. However, many antihistamine agents come with various undesirable side effects. Vegetal diamine oxidase (vDAO) might be a relevant alternative owing to its histaminase activity. Mammalian intestinal mucosa contains an endogenous DAO, yet possessing lower activity compared to that of vDAO preparation. Moreover, in several pathological conditions such as inflammatory bowel disease and irritable bowel syndrome, this endogenous DAO enzyme can be lost or inactivated. Here, we tested the therapeutic potential of vDAO by focusing on the well-known effect of histamine on gut motility. Using ex vivo and in vitro assays, we found that vDAO is more potent than commercial anti-histamine drugs at inhibiting histamine-induced contraction of murine distal colon muscles. We also identified pyridoxal 5′-phosphate (the biologically active form of vitamin B6) as an effective enhancer of vDAO antispasmodic activity. Furthermore, we discovered that rectally administered vDAO can be retained on gut mucosa and remain active. These observations make administration of vDAO in the gut lumen a valid alternative treatment for histamine-induced intestinal dysfunctions.

Characterization of Stressed Transgenic Mice Overexpressing H2-Histamine Receptors in the Heart

We studied transgenic mice with cardiac-specific overexpression of H₂-histamine receptors (H₂-TG) by using the α-myosin heavy-chain promoter. We wanted to address whether this overexpression would protect the heart against paradigmatic stressors. To this end, we studied isolated atrial preparations in an organ bath under normoxic and hypoxic conditions and after prolonged exposure to high histamine concentrations. Moreover, we assessed cardiac function using echocardiography in mice with cardiac hypertrophy due to overexpression of the catalytic subunit of PP2A (PP2A-TG) in the heart [H₂-TG × PP2A-TG = double transgenic (DT)] or H₂-TG with cardiac systolic failure due to treatment of mice with lipopolysaccharides (LPSs). Furthermore, the effect of ischemia and reperfusion was studied in isolated perfused hearts (Langendorff mode) of H₂-TG. We detected evidence for the protective role of the overexpressed H₂-histamine receptors in the contractile dysfunction of DT and isolated atrial preparations subjected to hypoxia. In contrast, we noted the detrimental role of H₂-histamine receptor overexpression against ischemia (Langendorff perfusion) and LPS-induced systolic heart failure. Hence, the role of H₂-histamine receptors in the heart is context-sensitive: the results differ between hypoxia (in atrium) and ischemia (perfused whole heart), as well as between genetically induced hypertrophy (DT) and toxin-induced heart failure (LPS). The underlying molecular mechanisms for the protective or detrimental roles of H₂-histamine receptor overexpression in the mammalian heart remain to be elucidated. SIGNIFICANCE STATEMENT: The beneficial and detrimental effects of the cardiac effects of H₂-histamine receptors in the heart under stressful conditions, here intended to mimic clinical situations, were studied. The data suggest that depending on the clinically underlying cardiac pathophysiological mechanisms, H₂-histamine agonists or H₂-histamine antagonists might merit further research efforts to improve clinical drug therapy.

Modulation of Ion Channels in the Superior Cervical Ganglion Neurons by Myocardial Ischemia and Fluvastatin Treatment

Background: The superior cervical ganglion (SCG) of the autonomic nervous system plays an important role in different cardiovascular diseases. In this study, we investigated the effects of ischemia and fluvastatin treatment on the ion channel characteristics of SCG neurons in a rabbit myocardial ischemia (MI) model.

Methods: MI was induced by abdominal subcutaneous injections of isoproterenol (ISO). The properties of the delayed rectifier potassium channel current (I_K), sodium channel current (I_Na), and action potential (APs) on isolated SCG neurons in the control, MI-7d, MI-14d, fluvastatin-7d (fluvastatin pretreated 14 days and treated 7 days after ISO-induced MI), and fluvastatin-14d (fluvastatin pretreated 14 days and treated 14 days after ISO-induced MI) groups were studied. In addition, the RNA expressions of KCNQ3 and SCN9A in the SCG tissue were determined by performing real-time PCR. Intracellular calcium concentration was monitored using laser scanning confocal microscopy.

Results: Compared with the control group, the current amplitude of I_K and I_Na were increased in the MI-7d and MI-14d groups. KCNQ3 RNA (corresponding to channel proteins of I_K) expression and SCN9A RNA (corresponding to channel proteins of I_Na) expression were also increased in MI groups. Activation and inactivation curves for I_Na in the two MI groups shifted negatively compared with the control group. These changes were reversed by fluvastatin treatment. Intracellular calcium concentration in SCG neurons was not altered significantly by MI or fluvastatin treatment. By contrast, increased AP amplitude and shortened APD₉₀ were observed in the MI-7d and MI-14d groups. These changes were reversed in the fluvastatin-treated MI group.

Conclusion: Fluvastatin treatment partly reversed the characteristics of SCG neurons in MI. The ion channel of SCG neurons could be one of the potential targets of fluvastatin in treating coronary heart diseases.

Cardioprotective effect of histamine H2 antagonists in congestive heart failure: A systematic review and meta-analysis

BACKGROUND

Histamine H2 antagonists (H2RAs) have long been suggested to have beneficial effects on congestive heart failure (CHF). However, full agreement about the cardioprotective effects of H2RAs is still not reached yet. Therefore, this study aims to clarify the effects of H2RAs on myocardial function in CHF patients by meta-analysis.

METHODS

Electronic databases including PubMed, Embase, and Cochrane Library were retrieved. Randomized controlled trials comparing the cardiac effects of H2RAs and placebo or other medicines were collected. Pooled mean differences (MDs) with 95% confidence intervals (CIs) were calculated and meta-analysis was performed using RevMan 5.3 software.

RESULTS

A total of 10 studies (472 participants) were included in this meta-analysis. H2RAs exhibited significant negative inotropic and chronotropic effects to reduce heart rate (MD: -3.90; 95%CI: -7.07 to -0.73, P = .02). Furthermore, although H2RAs did not affect the blood pressure in health volunteers, they significantly decreased the blood pressure of CHF patients. Additionally, H2RAs were also associated with significant increase in pre-ejection period and the ratio of pre-ejection period to left ventricular ejection time.

CONCLUSION

In summary, these findings showed that H2RAs exerted negative inotropic and chronotropic effects to reduce heart rate and blood pressure, which, similar to beta-adrenergic receptor blockers, might decrease myocardial oxygen demand and eventually result in improvement of CHF symptoms. These data provided further evidence for the effect of H2RAs on cardiac function and novel potential strategy for treatment of CHF.

Rat Models of Ventricular Fibrillation Following Acute Myocardial Infarction

A number of animal models have been designed in order to unravel the underlying mechanisms of acute ischemia-induced arrhythmias and to test compounds and interventions for antiarrhythmic therapy. This is important as acute myocardial infarction (AMI) continues to be the major cause of sudden cardiac death, and we are yet to discover safe and effective treatments of the lethal arrhythmias occurring in the acute setting. Animal models therefore continue to be relevant for our understanding and treatment of acute ischemic arrhythmias. This review discusses the applicability of the rat as a model for ventricular arrhythmias occurring during the acute phase of AMI. It provides a description of models developed, advantages and disadvantages of rats, as well as an overview of the most important interventions investigated and the relevance for human pathophysiology.

Analytical Methods for the Quantification of Histamine and Histamine Metabolites

The endogenous metabolite histamine (HA) is synthesized in various mammalian cells but can also be ingested from exogenous sources. It is involved in a plethora of physiological and pathophysiological processes. So far, four different HA receptors (H₁R-H₄R) have been described and numerous HAR antagonists have been developed. Contemporary investigations regarding the various roles of HA and its main metabolites have been hampered by the lack of highly specific and sensitive analytic methods for all of these analytes. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is the method of choice for identification and sensitive quantification of many low-molecular weight endogenous metabolites. In this chapter, different methodological aspects of HA quantification as well as recommendations for LC-MS/MS methods suitable for analysis of HA and its main metabolites are summarized.

Associations of Polymorphisms in HRH2, HRH3, DAO, and HNMT Genes with Risk of Chronic Heart Failure

The pathophysiological functions of cardiac histamine level and related histamine receptors during the development of chronic heart failure (CHF) were intensively investigated previously. However, the relevance of polymorphisms in histamine-related genes, such as HRH2, HRH3, DAO, and HNMT, with CHF remains largely neglected. This study herein aims to analyze the clinical associations of polymorphisms in those genes with CHF risk. A total of 333 unrelated Chinese Han CHF patients and 354 ethnicity-matched healthy controls were recruited and 11 single nucleotide polymorphisms (SNPs) were genotyped. We found that the HRH3 rs3787429 polymorphism was associated with CHF risk (p < 0.001). The T allele of rs3787429 exhibited protective effect against CHF under the dominant (ORs = 0.455; 95% CIs = 0.322–0.642) and additive models (ORs = 0.662; 95% CIs = 0.523–0.838), while, for SNPs in HRH2, DAO, and HNMT, no significant associations were observed in the present study. These findings for the first time screen out one SNP (rs3787429) of HRH3 gene that was significantly associated with CHF in Chinese Han population, which may be a novel biomarker for personal prevention and treatment of CHF and provides novel highlights for investigating the contribution of this disease.

Histamine deficiency exacerbates myocardial injury in acute myocardial infarction through impaired macrophage infiltration and increased cardiomyocyte apoptosis

Histamine is a biogenic amine that is widely distributed and has multiple functions, but the role it plays in acute myocardial infarction (AMI) remains unclear. In this study, we investigated the origin and contribution of endogenous histamine to AMI. Histidine decarboxylase (HDC) is the unique enzyme responsible for histamine generation. Using HDC-EGFP bacterial artificial chromosome (BAC) transgenic mice in which EGFP expression is controlled by the HDC promoter, we identified HDC expression primarily in CD11b(+)Gr-1(+) immature myeloid cells (IMCs) that markedly increase in the early stages of AMI. Deficiency of histamine in HDC knockout mice (HDC(-/-)) reduced cardiac function and exacerbated the injury of infarcted heart. Furthermore, administering either an H1 receptor antagonist (pyrilamine) or an H2 receptor antagonist (cimetidine) demonstrated a protective effect of histamine against myocardial injury. The results of in vivo and in vitro assays showed that histamine deficiency promotes the apoptosis of cardiomyocytes and inhibits macrophage infiltration. In conclusion, CD11b(+)Gr-1(+) IMCs are the predominant HDC-expressing sites in AMI, and histamine plays a protective role in the process of AMI through inhibition of cardiomyocyte apoptosis and facilitation of macrophage infiltration.

Relation of polymorphism of the histidine decarboxylase gene to chronic heart failure in Han Chinese

Histidine decarboxylase (HDC) is a key determinant of the levels of endogenous histamine that has long been recognized to play important pathophysiological roles during development of chronic heart failure (CHF). Meanwhile, certain genetic variants in HDC gene were reported to affect the function of HDC and associated with histamine-related diseases. However, the relation between polymorphisms of HDC gene and CHF risk remains unclear. This study aims to investigate the associations between 2 nonsynonymous HDC polymorphisms (rs17740607 and rs2073440) and CHF. We designed a 2-stage case-control study, in which we genotyped 439 patients with CHF and 467 healthy controls recruited in Xi'an, China, and replicated this study in 413 patients with CHF and 452 healthy subjects in Kunming, China. We also performed in vitro experiments to further validate the functional consequences of variants positively associated with CHF. The rs17740607 polymorphism showed replicated associations with all-cause CHF according to genotype and allele distribution and also under a dominant and additive genetic model after adjusted for traditional cardiovascular-related factors. Functional experiments further demonstrated that rs17740607 polymorphism decreased the HDC activity. In conclusion, HDC rs17740607 polymorphism is at least a partial loss-of-function variant and acts as a protective factor against CHF, which provides novel highlights for investigating the contribution of CHF.

The impact of mast cells on cardiovascular diseases

Mast cells comprise an innate immune cell population, which accumulates in tissues proximal to the outside environment and, upon activation, augments the progression of immunological reactions through the release and diffusion of either pre-formed or newly generated mediators. The released products of mast cells include histamine, proteases, as well as a variety of cytokines, chemokines and growth factors, which act on the surrounding microenvironment thereby shaping the immune responses triggered in various diseased states. Mast cells have also been detected in the arterial wall and are implicated in the onset and progression of numerous cardiovascular diseases. Notably, modulation of distinct mast cell actions using genetic and pharmacological approaches highlights the crucial role of this cell type in cardiovascular syndromes. The acquired evidence renders mast cells and their mediators as potential prognostic markers and therapeutic targets in a broad spectrum of pathophysiological conditions related to cardiovascular diseases.

Lack of Association between rs2067474 Polymorphism in Histamine Receptor H2 Gene and Breast Cancer in Chinese Han Population

Histamine H₂ receptor (HRH2) was previously suggested to affect the proliferation of breast cancer cells and disease-free survival of breast cancer patients. Furthermore, a common polymorphism, rs2067474, was identified in an enhancer element of the HRH2 gene promoter and was reported to be associated with various diseases including cancer. However, the relationship between this polymorphism and breast cancer risk and malignant degree remains unclear. The aim of this study was to clarify the clinical association of rs2067474 polymorphism with breast cancer. A total of 201 unrelated Chinese Han breast cancer patients and 238 ethnicity-matched health controls were recruited and rs2067474 polymorphism was genotyped. Logistic regression analyses were performed to calculate the odds ratios (ORs) as a measure of association of genotype with breast cancer according to 3 genetic models (dominant, recessive, and additive). Although the percentage of hormone receptor negative cases tended to be higher in AA genotypes, we did not find any significant associations of rs2067474 polymorphism with breast cancer risk or with related clinicopathological parameters in the present study, which indicates that rs2067474 polymorphism of HRH2 gene might not be a risk factor in the development of breast cancer in Chinese Han population.

Ellagic acid improved arrhythmias induced by CaCL2 in the rat stress model

OBJECTIVE

In ventricular arrhythmias, due to their free radical scavenging action, antioxidant agents are usually used in the treatment of cardiovascular disease. Since stress is considered as risk factor for increased mortality by causing malignant arrhythmias, the study was designed to evaluate the cardioprotective effects of ellagic acid (EA) on CaCl2-induced arrhythmias in rat stress model.

MATERIALS AND METHODS

Male Sprague-Dawley rats (200-250 g) were divided into four groups: Group I: Control rats (2 ml of saline by gavage), Group II: Rats treated with EA (15 mg/kg, gavage), Group III: stress group, Group IV: received EA plus stress. Stress was applied in a restrainer box (6 hour/day, 21 days). After induction of anesthesia, lead II electrocardiogram was recorded for calculating heart rate and QRS complex. The arrhythmia was produced by injection of CaCl2 solution (140 mg/kg, iv) and incidences of Ventricular fibrillation, Ventricular premature beats and Ventricular tachycardia were recorded. Results were analyzed by using one-way ANOVA and Fisher`s exact test. p<0.05 was considered as significant level.

RESULTS

The results showed a positive inotropic effect and negative chronotropic effect for the EA group in comparison with the control group. Incidence rates (%) of premature beats, ventricular fibrillation and ventricular tachycardia in stress group and all the arrhythmia parameters decreased in groups which received EA.

CONCLUSIONS

By decreasing the incidence rates of premature beats, fibrillation and ventricular tachycardia in groups which received EA, ellagic acid probably acted as an anti-arrhythmic agent which showed to have aprotective functionin heart.

Prediction of gene-phenotype associations in humans, mice, and plants using phenologs

Background

Phenotypes and diseases may be related to seemingly dissimilar phenotypes in other species by means of the orthology of underlying genes. Such “orthologous phenotypes,” or “phenologs,” are examples of deep homology, and may be used to predict additional candidate disease genes.

Results

In this work, we develop an unsupervised algorithm for ranking phenolog-based candidate disease genes through the integration of predictions from the k nearest neighbor phenologs, comparing classifiers and weighting functions by cross-validation. We also improve upon the original method by extending the theory to paralogous phenotypes. Our algorithm makes use of additional phenotype data — from chicken, zebrafish, and E. coli, as well as new datasets for C. elegans — establishing that several types of annotations may be treated as phenotypes. We demonstrate the use of our algorithm to predict novel candidate genes for human atrial fibrillation (such as HRH2, ATP4A, ATP4B, and HOPX) and epilepsy (e.g., PAX6 and NKX2-1). We suggest gene candidates for pharmacologically-induced seizures in mouse, solely based on orthologous phenotypes from E. coli. We also explore the prediction of plant gene–phenotype associations, as for the Arabidopsis response to vernalization phenotype.

Conclusions

We are able to rank gene predictions for a significant portion of the diseases in the Online Mendelian Inheritance in Man database. Additionally, our method suggests candidate genes for mammalian seizures based only on bacterial phenotypes and gene orthology. We demonstrate that phenotype information may come from diverse sources, including drug sensitivities, gene ontology biological processes, and in situ hybridization annotations. Finally, we offer testable candidates for a variety of human diseases, plant traits, and other classes of phenotypes across a wide array of species.

Cardiac electrophysiology in mice: a matter of size

Over the last decade, mouse models have become a popular instrument for studying cardiac arrhythmias. This review assesses in which respects a mouse heart is a miniature human heart, a suitable model for studying mechanisms of cardiac arrhythmias in humans and in which respects human and murine hearts differ. Section I considers the issue of scaling of mammalian cardiac (electro) physiology to body mass. Then, we summarize differences between mice and humans in cardiac activation (section II) and the currents underlying the action potential in the murine working myocardium (section III). Changes in cardiac electrophysiology in mouse models of heart disease are briefly outlined in section IV, while section V discusses technical considerations pertaining to recording cardiac electrical activity in mice. Finally, section VI offers general considerations on the influence of cardiac size on the mechanisms of tachy-arrhythmias.