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The isolated saline-perfused heart is used extensively to study cardiac physiology. Previous isolated heart studies have demonstrated lower tissue oxygenation compared with in vivo hearts based on myoglobin oxygenation and the mitochondrial redox state. These data, consistent with small anoxic regions, suggest that the homeostatic balance between work and oxygen delivery is impaired. We hypothesized that these anoxic regions are caused by inadequate local perfusion due to a paradoxical arteriole constriction generated by a disrupted vasoregulatory network. We tested this hypothesis by applying two exogenous vasodilatory agents, adenosine and cromakalim, to relax vascular tone in an isolated, saline-perfused, working rabbit heart. Oxygenation was monitored using differential optical transmission spectroscopy and full spectral fitting. Increases in coronary flow over control with adenosine (27 ± 4 ml/min) or cromakalim (44 ± 4 ml/min) were associated with proportional spectral changes indicative of myoglobin oxygenation and cytochrome oxidase (COX) oxidation, consistent with a decrease in tissue anoxia. Quantitatively, adenosine decreased deoxymyoglobin optical density (OD) across the wall by 0.053 ± 0.008 OD, whereas the reduced form of COX was decreased by 0.039 ± 0.005 OD. Cromakalim was more potent, decreasing deoxymyoglobin and reducing the level of COX by 0.070 ± 0.019 OD and 0.062 ± 0.019 OD, respectively. These effects were not species specific, as Langendorff-perfused mouse hearts treated with adenosine demonstrated similar changes. These data are consistent with paradoxical arteriole constriction as a major source of regional anoxia during saline heart perfusion. We suggest that the vasoregulatory network is disrupted by the washout of interstitial vasoactive metabolites in vitro. NEW & NOTEWORTHY Regional tissue anoxia is a common finding in the ubiquitous saline-perfused heart but is not found in vivo. Noninvasive optical techniques confirmed the presence of regional anoxia under control conditions and demonstrated that anoxia is diminished using exogenous vasodilators. These data are consistent with active arteriole constriction, occurring despite regional anoxia, generated by a disrupted vasoregulatory network. Washout of interstitial vasoactive metabolites may contribute to the disruption of normal vasoregulatory processes in vitro.

We study the conventional electron-phonon mediated superconducting properties of hole-doped black phosphorus by density functional calculations and get quite a large electron-phonon coupling (EPC) constant λ ~ 1.0 with transition temperature T C ~ 10 K, which is comparable to MgB 2 when holes are doped into the degenerate and nearly flat energy bands around the Fermi level. We predict that the softening of low-frequency [Formula: see text] optical mode and its phonon displacement, which breaks the lattice nonsymmorphic symmetry of gliding plane and lifts the band double degeneracy, lead to a large EPC. These factors are favorable for BCS superconductivity.

Objective: To evaluate the clinical diagnosis and treatment of hemorrhage after pancreatoduodenectomy via digital subtraction angiography (DSA) and transcatheter arterial embolization (TAE)., Methods: The clinical and imaging data of 23 patients receiving DSA examination and TAE treatment due to hemorrhage after pancreatoduodenectomy at our interventional center from October 2012 to October 2014 were retrospectively reviewed. And the manifestations of DSA and therapeutic efficacies of TAE were summarized and analyzed., Results: Among them, 16 patients showed positive signs of extravasation of contrast medium (n = 8), pseudoaneurysm formation (n = 3), ruptured pseudoaneurysm plus extravasation of contrast medium (n = 2) and local vascular spasm and non-smooth arterial intima (n = 3). And the remainder with negative signs (n = 7) underwent surgery. The 16 patients with positive signs underwent TAE with a technical success rate of 16/16. And clinical success was achieved in 12/16 patients. Among 4 rebleeders, two were successfully managed by surgery. And bleeding was caused by stress ulcer in gastrojejunal anastomosis (n = 1) and necrosis of pancreatic stump (n = 1). Another two on conservative treatment died from multiple organ failure., Conclusion: As first-line options, DSA and TAE are miniinvasive and accurate in the diagnosis and treatment of hemorrhage after pancreatoduodenectomy.

Previous studies have shown a role for nitric oxide and S-nitrosylation (SNO) in postconditioning (PostC), but specific SNO proteins and sites have not been identified in the myocardium after PostC. In this study, we examined SNO signaling in PostC using a Langendorff-perfused mouse heart model. After 20 min of equilibrium perfusion and 25 min of global ischemia, PostC was applied at the beginning of reperfusion with six cycles of 10 s of reperfusion and 10 s of ischemia. The total period of reperfusion was 90 min. Compared with the ischemia-reperfusion (I/R) control, PostC significantly reduced postischemic contractile dysfunction and infarct size. PostC-induced protection was blocked by treatment with N(G)-nitro-l-arginine methyl ester (l-NAME) (10 μmol/l; a constitutive NO synthase inhibitor), but not by either ODQ (10 μmol/l, a highly selective soluble guanylyl cyclase inhibitor) or KT5823 (1 μmol/l, a specific protein kinase G inhibitor). Two biotin switch based methods, two dimensional CyDye-maleimide difference gel electrophoresis (2D CyDye-maleimide DIGE) and SNO-resin-assisted capture (SNO-RAC), were utilized to identify SNO-modified proteins and sites. Using 2D CyDye-maleimide DIGE analysis, PostC was found to cause a 25% or greater increase in SNO of a number of proteins, which was blocked by treatment with l-NAME in parallel with the loss of protection. Using SNO-RAC, we identified 77 unique proteins with SNO sites after PostC. These results suggest that NO-mediated SNO signaling is involved in PostC-induced cardioprotection and these data provide the first set of candidate SNO proteins in PostC hearts.

Caveolae are flask-like invaginations of the plasma membrane enriched in cholesterol, sphingolipids, the marker protein caveolin and the coat protein cavin. In cardiomyocytes, multiple signaling molecules are concentrated and organized within the caveolae to mediate signaling transduction. Recent studies suggest that caveolae and caveolae-associated signaling molecules play an important role in protecting the myocardium against ischemia-reperfusion injury. For example, cardiac-specific overexpression of caveolin-3 has been shown to lead to protection that mimics ischemic preconditioning, while the knockout of caveolin-3 abolished ischemic preconditioning. In this review, we discuss the molecular mechanisms and signaling pathways that are involved in caveolae-mediated cardioprotection, and examine the potential for caveolae as a therapeutic target for pharmaceutical intervention to treat cardiovascular disease.

Methionine sulfoxide reductase A (MsrA) catalytically scavenges reactive oxygen species and also repairs oxidized methionines in proteins. Increasing MsrA protects cells and organs from a variety of oxidative stresses while decreasing MsrA enhances damage, but the mechanisms of action have not been elucidated. A single gene encodes MsrA of which ∼25% is targeted to the mitochondria, a major site of reactive oxygen species production. The other ∼75% is targeted to the cytosol and is posttranslationally modified by myristoylation. To determine the relative importance of MsrA in each compartment in protecting against ischemia-reperfusion damage, we created a series of transgenic mice overexpressing MsrA targeted to the mitochondria or the cytosol. We used a Langendorff model of ischemia-reperfusion and assayed both the rate pressure product and infarct size following ischemia and reperfusion as measures of injury. While the mitochondrially targeted MsrA was expected to be protective, it was not. Notably, the cytosolic form was protective but only if myristoylated. The nonmyristoylated, cytosolic form offered no protection against injury. We conclude that cytosolic MsrA protects the heart from ischemia-reperfusion damage. The requirement for myristoylation suggests that MsrA must interact with a hydrophobic domain to provide protection.

S-nitrosylation (SNO) is a reversible protein modification that has the ability to alter the activity of target proteins. However, only a small number of SNO proteins have been found in the myocardium, and even fewer specific sites of SNO have been identified. Therefore, this study aims to characterize potential SNO sites in the myocardium. We utilized a modified version of the SNO-resin-assisted capture technique in tandem with mass spectrometry. In brief, a modified biotin switch was performed using perfused mouse heart homogenates incubated with or without the S-nitrosylating agent S-nitrosoglutathione. Our modified SNO-resin-assisted capture protocol identified 116 unique SNO-modified proteins under basal conditions, and these represent the constitutive SNO proteome. These constitutive SNO proteins are likely to be physiologically relevant targets, since nitric oxide has been shown to play an important role in the regulation of normal cardiovascular physiology. Following S-nitrosoglutathione treatment, we identified 951 unique SNO proteins, many of which contained multiple SNO sites. These proteins show the potential for SNO. This study provides novel information regarding the constitutive SNO proteome of the myocardium, as well as potential myocardial SNO sites, and yields additional information on the SNO sites for many key proteins involved in myocardial contraction, metabolism, and cellular signaling.

Nitric oxide (NO) has been shown as an important signaling messenger involved in cardioprotection of ischemic preconditioning (IPC). To date, most studies suggest that NO might provide its protective effects by regulating the mitochondrial ATP-sensitive potassium (K(ATP)) channel via the classic NO/cGMP-dependent pathway. However, there is emerging data suggesting that NO might also elicit its physiological role through protein S-nitrosylation. Protein S-nitrosylation, the covalent attachment of an NO moiety to sulfhydryl group(s) of cysteine residue(s) of proteins, is a reversible post-translational protein modification involved in redox-based cellular signaling. IPC has been found to increase S-nitrosothiol content and result in increased S-nitrosylation of proteins, which not only induces the structural and functional changes of modified proteins, but also prevents the target cysteine residue(s) from the further oxidative modification. In addition, S-nitrosothiols could elicit pharmacological preconditioning effect and protect against myocardial ischemia-reperfusion injury. Thus, protein S-nitrosylation is emerging as an important contributor to cardioprotection in IPC, providing protection from cellular oxidative and nitrosative stress.

Mechanisms underlying gender differences in cardiovascular disease are poorly understood. We found previously that, under hypercontractile conditions, female hearts exhibit significantly less ischemia/reperfusion injury than males. Here we show that male wild-type (WT) mouse hearts pretreated with 10 nmol/L isoproterenol before ischemia exhibited increased injury versus female hearts, but this relative protection in females was absent in eNOS(-/-) and nNOS(-/-) hearts. In isoproterenol-treated female versus male hearts, there was also more endothelial NO synthase (eNOS) associated with cardiomyocyte caveolin-3, and more neuronal NOS (nNOS) translocation to caveolin-3 during ischemia/reperfusion. S-nitrosothiol (SNO) formation was increased in isoproterenol-treated ischemic/reperfused hearts in all mouse genotypes, but only in WT mice was SNO content significantly higher in females than males. Using the biotin switch method, we identified the L-type Ca2+ channel alpha1 subunit as the predominant S-nitrosylated protein in membrane fractions, and following isoproterenol and ischemia/reperfusion male/female differences in SNO were seen only in WT hearts, but not in constitutive NOS(-/-) genotypes. The isoproterenol-induced increase in L-type Ca2+ current (ICa) was smaller in females versus in males, but NOS blockade increased ICa in females. This gender difference in ICa in isoproterenol-treated myocytes (and abolition on NOS inhibition) was mirrored exactly in Ca2+ transients and SR Ca2+ contents. In conclusion, these data suggest that eNOS and nNOS both play roles in the gender differences observed in ischemia/reperfusion injury under adrenergic stimulation, and also demonstrate increased S-nitrosylation of the L-type Ca2+ channels in female cardiomyocytes.