Cantharidin and sodium fluoride attenuate the negative inotropic effects of carbachol in the isolated human atrium.

Carbachol, an agonist at muscarinic receptors, exerts a negative inotropic effect in human atrium. Carbachol can activate protein phosphatases (PP1 or PP2A). We hypothesized that cantharidin or sodium fluoride, inhibitors of PP1 and PP2A, may attenuate a negative inotropic effect of carbachol. During bypass-surgery trabeculae carneae of human atrial preparations (HAP) were obtained. These trabeculae were mounted in organ baths and electrically stimulated (1 Hz). Force of contraction was measured under isometric conditions. For comparison, we studied isolated electrically stimulated left atrial preparations (LA) from mice. Cantharidin (100 µM) and sodium fluoride (3 mM) increased force of contraction in LA (n = 5-8, p < 0.05) by 113% ± 24.5% and by 100% ± 38.2% and in HAP (n = 13-15, p < 0.05) by 625% ± 169% and by 196% ± 23.5%, respectively. Carbachol (1 µM) alone exerted a rapid transient maximum negative inotropic effect in LA (n = 6) and HAP (n = 14) to 46.9% ± 3.63% and 19.4% ± 3.74%, respectively (p < 0.05). These negative inotropic effects were smaller in LA (n = 4-6) and HAP (n = 9-12) pretreated with 100 µM cantharidin and amounted to 58.0% ± 2.27% and 59.2% ± 6.19% or 3 mM sodium fluoride to 63.7% ± 9.84% and 46.3% ± 5.69%, (p < 0.05). We suggest that carbachol, at least in part, exerts a negative inotropic effect in the human atrium by stimulating the enzymatic activity of PP1 and/or PP2A.

Ergotamine Stimulates Human 5-HT4-Serotonin Receptors and Human H2-Histamine Receptors in the Heart.

Ergotamine (2'-methyl-5'α-benzyl-12'-hydroxy-3',6',18-trioxoergotaman) is a tryptamine-related alkaloid from the fungus Claviceps purpurea. Ergotamine is used to treat migraine. Ergotamine can bind to and activate several types of 5-HT1-serotonin receptors. Based on the structural formula of ergotamine, we hypothesized that ergotamine might stimulate 5-HT4-serotonin receptors or H2-histamine receptors in the human heart. We observed that ergotamine exerted concentration- and time-dependent positive inotropic effects in isolated left atrial preparations in H2-TG (mouse which exhibits cardiac-specific overexpression of the human H2-histamine receptor). Similarly, ergotamine increased force of contraction in left atrial preparations from 5-HT4-TG (mouse which exhibits cardiac-specific overexpression of the human 5-HT4-serotonin receptor). An amount of 10 µM ergotamine increased the left ventricular force of contraction in isolated retrogradely perfused spontaneously beating heart preparations of both 5-HT4-TG and H2-TG. In the presence of the phosphodiesterase inhibitor cilostamide (1 µM), ergotamine 10 µM exerted positive inotropic effects in isolated electrically stimulated human right atrial preparations, obtained during cardiac surgery, that were attenuated by 10 µM of the H2-histamine receptor antagonist cimetidine, but not by 10 µM of the 5-HT4-serotonin receptor antagonist tropisetron. These data suggest that ergotamine is in principle an agonist at human 5-HT4-serotonin receptors as well at human H2-histamine receptors. Ergotamine acts as an agonist on H2-histamine receptors in the human atrium.

Synthetic antibody-derived immunopeptide provides neuroprotection in glaucoma through molecular interaction with retinal protein histone H3.1.

Glaucoma is a group of optic neuropathies characterized by the progressive degeneration of retinal ganglion cells (RGCs) as well as their axons leading to irreversible loss of sight. Medical management of the intraocular pressure (IOP) still represents the gold standard in glaucoma therapy, which only manages a single risk factor and does not directly address the neurodegenerative component of this eye disease. Recently, our group showed that antibody-derived immunopeptides (encoding complementarity-determining regions, CDRs) provide attractive glaucoma medication candidates and directly interfere its pathogenic mechanisms by different modes of action. In accordance with these findings, the present study showed the synthetic complementary-determining region 2 (CDR2) peptide (INSDGSSTSYADSVK) significantly increased RGC viability in vitro in a concentration-dependent manner (p < 0.05 using a CDR2 concentration of 50 µg/mL). Employing state-of the-art immunoprecipitation experiments, we confirmed that synthetic CDR2 exhibited a high affinity toward the retinal target protein histone H3.1 (HIST1H3A) (p < 0.001 and log2-fold change > 3). Furthermore, molecular dynamics (MD) simulations along with virtual docking analyses predicted potential CDR2-specific binding regions of HIST1H3A, which might represent essential post-translational modification (PTM) sites for epigenetic regulations. Quantitative mass spectrometry (MS) analysis of retinas demonstrated 39 proteins significantly affected by CDR2 treatment (p < 0.05). An up-regulation of proteins involved in the energy production (e.g., ATP5F1B and MT-CO2) as well as the regulatory ubiquitin proteasome system (e.g., PSMC5) was induced by the synthetic CDR2 peptide. On the other hand, CDR2 reduced metabolic key enzymes (e.g., DDAH1 and MAOB) as well as ER stress-related proteins (e.g., SEC22B and VCP) and these data were partially confirmed by microarray technology. Our outcome measurements indicate that specific protein-peptide interactions influence the regulatory epigenetic function of HIST1H3A promoting the neuroprotective mechanism on RGCs in vitro. In addition to IOP management, such synthetic peptides as CDR2 might serve as a synergistic immunotherapy for glaucoma in the future.

Functional interaction of H2-receptors and 5HT4-receptors in atrial tissues isolated from double transgenic mice and from human patients.

In the past, we generated transgenic mice that overexpress the human histamine 2 (H2)-receptor (H2-TG) or that overexpress the human serotonin 4 (5-HT4)-receptor (5-HT4-TG) in the heart. Here, we crossbred these lines of mice to generate double transgenic mice that overexpress both receptors (DT). This was done to study a conceivable interaction between these receptors in the mouse heart as a model for the human heart. When in left atria, initially, force of contraction was elevated maximally with 1 µM serotonin, and subsequently, histamine was cumulatively applied; a biphasic effect of histamine was noted: the force of contraction initially decreased, maximally at 10 nM histamine, and thereafter, the force of contraction increased again at 1 µM histamine. Notably, functional interaction between 5-HT and histamine was also identified in isolated electrically stimulated trabeculae carneae from human right atrium (obtained during cardiac surgery). These functional and biochemical data together are consistent with a joint overexpression of inotropically active H2-receptors and 5-HT4-receptors in the same mouse heart. We also describe an antagonistic interaction on the force of contraction of both receptors in the mouse atrium (DT) and in the human atrial muscle strips. We speculate that via this interaction, histamine might act as a "brake" on the cardiac actions of 5-HT via inhibitory GTP-binding proteins acting on the activity of adenylyl cyclase.

Cardiac Effects of Novel Histamine H2 Receptor Agonists.

In an integrative approach, we studied cardiac effects of recently published novel H2 receptor agonists in the heart of mice that overexpress the human H2 receptor (H2-TG mice) and littermate wild type (WT) control mice and in isolated electrically driven muscle preparations from patients undergoing cardiac surgery. Under our experimental conditions, the H2 receptor agonists UR-Po563, UR-MB-158, and UR-MB-159 increased force of contraction in left atrium from H2-TG mice with pEC50 values of 8.27, 9.38, and 8.28, respectively, but not in WT mice. Likewise, UR-Po563, UR-MB-158, and UR-MB-159 increased the beating rate in right atrium from H2-TG mice with pEC50 values of 9.01, 9.24, and 7.91, respectively, but not from WT mice. These effects could be antagonized by famotidine, a H2 receptor antagonist. UR-Po563 (1 µM) increased force of contraction in Langendorff-perfused hearts from H2-TG but not WT mice. Similarly, UR-Po563, UR-MB-158, or UR-MB-159 increased the left ventricular ejection fraction in echocardiography of H2-TG mice. Finally, UR-Po563 increased force of contraction in isolated human right atrial muscle strips. The contractile effects of UR-Po563 in H2-TG mice were accompanied by an increase in the phosphorylation state of phospholamban. In summary, we report here three recently developed agonists functionally stimulating human cardiac H2 receptors in vitro and in vivo. We speculate that these compounds might be of some merit to treat neurologic disorders if their cardiac effects are blocked by concomitantly applied receptor antagonists that cannot pass through the blood-brain barrier or might be useful to treat congestive heart failure in patients. SIGNIFICANCE STATEMENT: Recently, a new generation of histamine H2 receptor (H2R) agonists has been developed as possible treatment option for Alzheimer's disease. Here, possible cardiac (side) effects of these novel H2R agonists have been evaluated.

One-year outcomes of cohort 1 in the Edwards SAPIEN Aortic Bioprosthesis European Outcome (SOURCE) registry: the European registry of transcatheter aortic valve implantation using the Edwards SAPIEN valve.

BACKGROUND: Transcatheter aortic valve implantation was developed to provide a therapeutic option for patients considered to be ineligible for, and to mitigate mortality and morbidity associated with, high-risk surgical aortic valve replacement. METHODS AND RESULTS: The Edwards SAPIEN Aortic Bioprosthesis European Outcome (SOURCE) Registry was designed to assess initial post commercial clinical transcatheter aortic valve implantation results of the Edwards SAPIEN valve in consecutive patients in Europe. Cohort 1 consists of 1038 patients enrolled at 32 centers. One-year outcomes are presented. Patients with the transapical approach (n=575) suffered more comorbidities than transfemoral patients (n=463) with a significantly higher logistic EuroSCORE (29% versus 25.8%; P=0.007). These groups are different; therefore, outcomes cannot be directly compared. Total Kaplan Meier 1-year survival was 76.1% overall, 72.1% for transapical and 81.1% for transfemoral patients, and 73.5% of surviving patients were in New York Heart Association (NYHA) class I or II at 1 year. Combined transapical and transfemoral causes of death were cardiac in 25.1%, noncardiac in 49.2%, and unknown in 25.7%. Pulmonary complications (23.9%), renal failure (12.5%), cancer (11.4%), and stroke (10.2%) were the most frequent noncardiac causes of death. Multivariable analysis identified logistic EuroSCORE, renal disease, liver disease, and smoking as variables with the highest hazard ratios for 1-year mortality whereas carotid artery stenosis, hyperlipidemia, and hypertension were associated with lower mortality. CONCLUSION: The SOURCE Registry is the largest consecutively enrolled registry for transcatheter aortic valve implantation procedures. It demonstrates that with new transcatheter aortic techniques excellent 1-year survival in high-risk and inoperable patients is achievable and provides a benchmark against which future transcatheter aortic valve implantation cohorts and devices can be measured.

Hepatitis A virus protein 2B suppresses beta interferon (IFN) gene transcription by interfering with IFN regulatory factor 3 activation.

Hepatitis A virus (HAV) antagonizes the innate immune response by inhibition of retinoic acid-inducible gene I-mediated and melanoma differentiation-associated gene 5-mediated beta interferon (IFN-beta) gene expression. This study showed that this is due to an interaction of HAV with mitochondrial antiviral signalling protein (MAVS)-dependent signalling, in which the viral non-structural protein 2B and the protein intermediate 3ABC recently suggested in this context seem to be involved, cooperatively affecting the activities of MAVS and the kinases TANK-binding kinase 1 (TBK1) and the inhibitor of NF-kappaB kinase epsilon (IKKepsilon). In consequence, interferon regulatory factor 3 (IRF-3) is not activated. As IRF-3 is necessary for IFN-beta transcription, inhibition of this factor results in efficient suppression of IFN-beta synthesis. This ability might be of vital importance for HAV, which is an exceptionally slow growing virus sensitive to IFN-beta, as it allows the virus to establish infection and maintain virus replication for a longer period of time.

Impact of total lymph node count on staging and survival after gastrectomy for gastric cancer: data from a large US-population database.

BACKGROUND: Prognosis of potentially curable (M0), completely resected gastric cancer is primarily determined by pathologic T and N staging criteria. The optimal regional dissection extent during gastrectomy for gastric adenocarcinoma continues to be debated. METHODS: A gastric cancer data set was created through structured queries to the Surveillance, Epidemiology, and End Results database (1973 to 1999). Relationships between the number of lymph nodes (LNs) examined and survival were analyzed for the stage subgroups T1/2N0, T1/2N1, T3N0, and T3N1. RESULTS: In every stage subgroup, overall survival was highly dependent on the number of LNs examined. Multivariate prognostic variables in the T1/2N0M0 subgroup were number of LNs examined, age (for both, P < .0001), race (P = .0004), sex (P = .0006), and tumor size (P = .02). A linear trend for superior survival based on more LNs examined could be confirmed for all four stage subgroups. Baseline model-predicted 5-year survival with only one LN examined was 56% (T1/2N0), 35% (T1/2N1), 29% (T3N0), or 13% (T3N1). For every 10 extra LNs dissected, survival improved by 7.6% (T1/2N0), 5.7% (T1/2N1), 11% (T3N0), or 7% (T3N1). A cut-point analysis yielded the greatest survival difference at 10 LNs examined but continued to detect significantly superior survival differences for cut points at up to 40 LNs, always in favor of more LNs examined. CONCLUSION: Although the impact of stage migration versus improved regional disease control cannot be separated on basis of the available information, the data provide support in favor of extended lymphadenectomy during potentially curative gastrectomy for gastric cancer.