A protective role of Nox1/NADPH oxidase in a mouse model with hypoxia-induced bradycardia.

Although it has been reported that endotoxin-induced expression of Nox1 in the heart contributes to apoptosis in cardiomyocytes, functional role of Nox1 at the physiological expression level has not been elucidated. The aim of this study was to clarify the role of Nox1 under a hypoxic condition using wild-type (WT, Nox1(+/Y)) and Nox1-deficient (Nox1(-/Y)) mice. ECG recordings from anesthetized mice revealed that Nox1(-/Y) mice were more sensitive to hypoxia, resulting in bradycardia, compared to WT mice. Atrial and ventricular electrocardiograms recorded from Langendorff-perfused hearts revealed that hypoxic perfusion more rapidly decreased heart rate in Nox1(-/Y) hearts compared with WT hearts. Sinus node recovery times measured under a hypoxic condition were prolonged more markedly in the Nox1(-/Y) hearts. Sinoatrial node dysfunction of Nox1(-/Y) hearts during hypoxia was ameriolated by the pre-treatment with the Ca(2+) channel blocker nifedipine or the K(+) channel opener pinacidil. Spontaneous action potentials were recorded from enzymatically-isolated sinoatrial node (SAN) cells under a hypoxic condition. There was no significant difference in the elapsed times from the commencement of hypoxia to asystole between WT and Nox1(-/Y) SAN cells. These findings suggest that Nox1 may have a protective effect against hypoxia-induced SAN dysfunction.

Termination of aconitine-induced atrial fibrillation by the KACh-channel blocker tertiapin: underlying electrophysiological mechanism.

The acetylcholine receptor-operated K(+) (KACh) channel may be a novel target for atrial-specific antiarrhythmic therapy. Recently it has been demonstrated that tertiapin, a selective blocker of KACh channel, suppressed aconitine-induced atrial fibrillation (AF) in dogs. However, the precise mechanism by which the KACh-channel blocker inhibits the aconitine-induced AF remains unknown. This study was undertaken to determine the role of KACh channel in aconitine-induced AF in guinea pigs. Tertiapin terminated the aconitine-induced AF in anesthetized guinea pigs. The results of an in vitro electrophysiological experiment using atrial cells and atrial preparations suggest that aconitine might activate KACh channels in atrial cells, probably by intracellular Na(+) accumulation, and inhibition of KACh channels by tertiapin might suppress AF by producing conduction block, probably due to further decrease in the resting membrane potential. Since it has been reported that constitutively active KACh channels can be observed in atrial cells of patients with chronic AF, aconitine-induced AF may be used as an experimental model for evaluation of drug effect on chronic AF.

Hemodialysis as a Risk Factor for Ceftriaxone-Associated Pseudolithiasis in Adults.

Ceftriaxone-associated biliary pseudolithiasis is common among children; however, there are only a few reports of pseudolithiasis in adult patients on HD. This retrospective cohort study included 278 adult patients on ceftriaxone therapy from 1 February 2016 to 1 September 2018. Pseudolithiasis was defined as a new development of sludge or stones in the gallbladder within 60 days of ceftriaxone therapy. After excluding patients with preexisting gallstones and a history of cholecystectomy, 113 patients on maintenance HD, and another 98 patients were enrolled as the HD and control group, respectively. Thirteen patients developed pseudolithiasis. Its incidence was significantly higher in the HD group than that in the control group. Multivariate logistic regression analyses showed that development of pseudolithiasis was significantly associated with HD and ceftriaxone dose. Therefore, HD in patients receiving ceftriaxone therapy appears to be associated with a risk of pseudolithiasis. These findings highlight the need for careful follow-up.

Infarct size limitation by adrenomedullin: protein kinase A but not PI3-kinase is linked to mitochondrial KCa channels.

AIM: Adrenomedullin (ADM) has been shown to protect the heart against ischaemic injury, but little is known of the underlying mechanism. Mitochondrial Ca(2+)-activated K(+) (mitoK(Ca)) channels play a key role in cardioprotection. This study examined whether mitoK(Ca) channel is involved in the protection afforded by ADM. METHODS: Flavoprotein fluorescence in rabbit ventricular myocytes was measured to assay mitoK(Ca) channel activity. Infarct size in the isolated perfused rabbit hearts subjected to 30-min global ischaemia and 120-min reperfusion was determined by triphenyltetrazolium chloride staining. RESULTS: The mitoK(Ca) channel opener NS1619 (30 microM) partially oxidized flavoprotein. ADM (10 nM) augmented the NS1619-induced flavoprotein oxidation when applied after the effect of NS1619 had reached steady state. This potentiating effect of ADM was prevented by the protein kinase A (PKA) inhibitor KT5720 (200 nM), but not by the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002 (5 microM). The mitoK(Ca) channel blocker paxilline (PX, 2 microM) completely blocked the oxidative effects of NS1619 in the presence of ADM. Treatment with ADM for 10 min before ischaemia significantly reduced infarct size after ischaemia/reperfusion from 63 +/- 3% in controls to 32 +/- 4% (P < 0.01). This infarct size-limiting effect of ADM was abolished by PX (61 +/- 2%), as well as by KT5720 (62 +/- 3%). ADM treatment for the first 10 min of reperfusion significantly reduced infarct size compared with controls (42 +/- 3%, P < 0.01). This cardioprotective effect of ADM was unaffected by PX (38 +/- 4%), but was abolished by LY294002 (60 +/- 4%). CONCLUSIONS: ADM augments the opening of mitoK(Ca) channels by PKA activation, but not by PI3-K activation. ADM treatment prior to ischaemia reduces infarct size via PKA-mediated activation of mitoK(Ca) channels. On the other hand, ADM treatment upon reperfusion reduces infarct size via a PI3-K-mediated pathway without activating mitoK(Ca) channels.

6-[4-(1-Cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2-(1H)quinolinone (cilostazol), a phosphodiesterase type 3 inhibitor, reduces infarct size via activation of mitochondrial Ca2+-activated K+ channels in rabbit hearts.

6-[4-(1-Cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2-(1H)quinolinone (cilostazol), a phosphodiesterase type 3 (PDE III) inhibitor, activates cAMP-dependent protein kinase A (PKA). The cAMP/PKA pathway potentiates the opening of mitochondrial Ca(2+)-activated K(+) (mitoK(Ca)) channels and confers cardioprotection. Although cilostazol has been reported to directly activate sarcolemmal large-conductance Ca(2+)-activated K(+) channels, it remains unclear whether cilostazol modulates the opening of mitoK(Ca) channels. Therefore, we tested the possibility that cilostazol opens mitoK(Ca) channels and protects hearts against ischemia/reperfusion injury. Flavoprotein fluorescence in rabbit ventricular myocytes was measured to assay mitoK(Ca) channel activity. Infarct size in the isolated perfused rabbit hearts subjected to 30-min global ischemia and 120-min reperfusion was determined by triphenyltetrazolium chloride staining. Cilostazol (1, 3, 10, and 30 microM) oxidized flavoprotein in a concentration-dependent manner. The oxidative effect of cilostazol (10 microM) was antagonized by the mitoK(Ca) channel blocker paxilline (2 microM). Activation of PKA by 8-bromoadenosine 3'5'-cyclic monophosphate (0.5 mM) potentiated the cilostazol-induced flavoprotein oxidation. Treatment with cilostazol (10 microM) for 10 min before ischemia significantly reduced the infarct size from 67.2 +/- 1.3 (control) to 33.6 +/- 5.3% (p < 0.05). This infarct size-limiting effect of cilostazol was abolished by paxilline (60.3 +/- 4.9%) but not by the PKA inhibitor (9S,10S,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]-benzodiazocine-10-carboxylic acid hexyl ester (KT5720) (200 nM, 40.5 +/- 3.5%). On the other hand, another PDE III inhibitor, milrinone (10 microM), neither oxidized flavoprotein nor reduced infarct size. Our results suggest that cilostazol exerts a cardioprotective effect via direct activation of mitoK(Ca) channels.

Physicochemical, morphological and therapeutic evaluation of agarose hydrogel particles as a reservoir for basic fibroblast growth factor.

Micron-sized agarose hydrogel particles were prepared using an emulsification/gelation method as a controlled release reservoir for basic fibroblast growth factor (bFGF). Mean particle size of agarose hydrogel particles decreased with an increase in stirring speed and also with an increasing temperature of the oil phase, as measured before cooling. Morphologies of agarose particles before and after dispersing into water were investigated by scanning electron microscopy (SEM) and cryogenic SEM, respectively. Freeze-dried agarose particles were spherical with rough surface. Porous polymer matrix structure was observed in the hydrogel particles by cryo-SEM. More than 99% of bFGF was encapsulated and the release from the agarose hydrogel particles was less than 3% during the incubation in phosphate buffered saline. bFGF molecules were not only adsorbed on the particle surface but also permeated and retained within the matrix. The therapeutic efficacy of bFGF retained in agarose hydrogel particles was significantly higher than that dissolved in saline. Agarose hydrogel particle seems to be a potential candidate for a bFGF reservoir.

Late-term regression of stenosis at the kink site in the internal thoracic artery in two cases.

A kink in the internal thoracic artery (ITA) is a rare postoperative complication after coronary artery bypass surgery. The kink can be accompanied by significant stenosis and has been observed after the ITAs are harvested by the skeletonization method. In this report, we present two cases in which early postoperative angiography showed the kink accompanied by significant stenosis, and late angiography revealed regression of stenosis at the kink site. Immediate intervention is not always necessary even when the kink, accompanied by significant stenosis was observed on early postoperative angiography.

Mitral stenosis after mitral valve repair using the duran flexible annuloplasty ring for degenerative mitral regurgitation.

The case is presented of a 47-year-old woman who had undergone mitral valve repair using the Duran annuloplasty ring four years earlier, and who was diagnosed with mitral stenosis owing to fibrous tissue overgrowth. In this patient, dense whitish fibrous tissue covered the annuloplasty ring and extended onto both leaflets of the mitral valve, narrowing its orifice and rendering the leaflets stiff and immobile. The pannus covering the mitral valve could not be stripped off without damaging the leaflets, making mitral valve replacement necessary. Mitral valve replacement with a St. Jude Medical mechanical heart valve prosthesis was successfully performed, and no major perioperative complications were encountered.

Long-term evaluation of bovine pericardial bioprostheses in young women: influence of pregnancy.

OBJECTIVES: To avoid the fetal and maternal risks associated with anticoagulant therapy during pregnancy, the use of bioprostheses has been advocated for young women with cardiac valve disease during the childbearing years. Several reports have suggested the probability of pregnancy-related accelerated structural valve deterioration (SVD). The aim of this study was to assess the effect of pregnancy and delivery on bovine pericardial bioprostheses. METHODS: Between 1986 and 2004, 13 female patients received 14 bioprostheses. The women were segregated into two groups based on whether pregnancy occurred during follow-up: eight in the Pregnant Group (Group P) (including one case who underwent two operations), and six in the Nonpregnant Group (Group NP). RESULT: Early mortality was not observed. Late mortality was 12.5% for Group P and 16.7% for Group NP. There were a total of ten valve-related reoperations (seven in Group P and three in Group NP); the major reason was SVD in 64.3% of the cases. Freedom from valve-related reoperation at nine years was 28.6% in Group P and 33.3% in Group NP (p=0.338). Overall time from primary surgery to reoperation was 111 +/- 24.7 months, with no significant difference between the two groups (p=0.615). The Group P of eight patients had 12 pregnancies: ten deliveries and two abortions. There were no maternal or neonatal deaths. CONCLUSION: Pregnancy did not significantly influence the incidence of SVD and reoperation. The bioprostheses appears to provide female patients with more opportunity for uncomplicated pregnancies, deliveries and normal children than mechanical valves.

Biochemistry and physiology of mitochondrial ion channels involved in cardioprotection.

Over the past decades there has been considerable progress in understanding the multifunctional roles of mitochondrial ion channels in metabolism, energy transduction, ion transport, signaling, and cell death. Recent data have suggested that some of these channels function under physiological condition, and others may be activated in response to pathological insults and play a key role in cytoprotection. This review outlines our current understanding of the molecular identity and pathophysiological roles of the mitochondrial ion channels in the heart with particular emphasis on cardioprotection against ischemia/reperfusion injury, and future research on mitochondrial ion channels.

New aspects for the treatment of cardiac diseases based on the diversity of functional controls on cardiac muscles: mitochondrial ion channels and cardioprotection.

Mitochondrial ATP-sensitive K(+) (mitoK(ATP)) and Ca(2+)-activated K(+) (mitoK(Ca)) channels exist in cardiac myocytes, and they play key roles in cardioprotection. We have recently reported that K(+) influx through mitoK(ATP) or mitoK(Ca) channels occurs independently of each other and confers cardioprotection in a similar manner. Activation of mitoK(ATP) channel is augmented by protein kinase C (PKC), whereas mitoK(Ca) channel is activated by protein kinase A (PKA). However, phosphatidylinositol 3-kinase (PI3-K) is linked to neither mitoK(ATP) nor mitoK(Ca) channels. We have demonstrated that bioactive substances modulate the opening of mitoK(ATP) channels via a PKC-dependent pathway or opening of mitoK(Ca) channels via a PKA-dependent pathway and thereby protecting the heart from ischemia/reperfusion injury. Several endogenous substances such as adenosine and bradykinin can reduce infarct size by activation of mitoK(ATP) channels in a PKC-dependent manner. Adrenomedullin, a potent vasodilator peptide, potentiates the opening of mitoK(Ca) channels by PKA activation. Treatment with adrenomedullin prior to ischemia results in the reduction of infarct size via a PKA-mediated activation of mitoK(Ca) channels. Thus, some endogenous substances confer cardioprotection via PKA- or PKC-mediated activation of mitoK(ATP) or mitoK(Ca) channels.

Glimepiride treatment upon reperfusion limits infarct size via the phosphatidylinositol 3-kinase/Akt pathway in rabbit hearts.

The phenomenon termed postconditioning, that is, brief episodes of ischemia/reperfusion at the onset of reperfusion reduce infarct size, is thought to involve the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Treatment with a drug activating PI3K at the onset of reperfusion may confer a similar cardioprotection. The sulfonylurea glimepiride has been shown to activate PI3K in human endothelial cells. We therefore tested in rabbit hearts whether glimepiride can produce postconditioning-mimetic actions. Langendorff-perfused rabbit hearts were subjected to 30 min of global ischemia and 120 min of reperfusion, and infarct size was determined by triphenyltetrazolium staining. Phosphorylation of Akt was analyzed by Western blotting. Glimepiride (10 microM) treatment for the first 10 min of reperfusion significantly reduced infarct size from 67.2 +/- 1.3% in controls to 35.8 +/- 4.5% (P < 0.01). This infarct size-limiting effect of glimepiride was abolished by a selective inhibitor of PI3K (5 microM LY294002, 65.4 +/- 3.4%). Phosphorylation of the PI3K substrate Akt was significantly increased in glimepiride-treated hearts when compared to controls (P < 0.05). Glimepiride-induced Akt phosphorylation was inhibited by LY294002. In conclusion, our study demonstrates that glimepiride treatment upon reperfusion reduces infarct size in rabbit hearts via a PI3K/Akt-mediated pathway. The postconditioning-mimetic action of glimepiride may be beneficial for the treatment of diabetic patients with ischemic heart disease.

[Inactivation mechanism of microorganisms by the synergy of silver and light irradiation, and the application in household electrical appliances].

The inactivation efficiencies of microorganisms were found to be enhanced by using silver solution together with ultraviolet light (UV-A, 395 nm) irradiation. The inactivation efficiencies were improved remarkably especially in eukaryotic microorganism. To make clear the inactivation mechanism of microorganisms by the combination effect of silver and ultraviolet light irradiation, the resultant solution was characterized by ESR (Electron spin resonance, ESR). Scanning electron microscopy (SEM) and the methnd for measuring enzyme activity of mitochondria for eukarvotic cells were used to conjecture the mechanism, by analysis of the morphological and physiologic changes in eukaryotic cells. It is proposed that silver oxide (Ag20) can be activated by ultraviolet light irradiation and react with water molecules to produce hydroxyl radical (.OH). Hydroxyl radical could damage cell wall of eukaryotic microorganisms, and inactivate the enzyme activity of mitochondria of eukaryotic microorganism cells. Accordingly, eukaryotic microorganism cells would die. In the experiment, Staphylococcus aureus was employed as the representative of prokaryotic microorganisms, and Candida albicans and Trichophyton mentagrophytes as the representative of eukaryotic microorganisms, respectively. Moreover, the results of the technology applied to washing machine were presented and discussed.

Effects of sulfonylureas on mitochondrial ATP-sensitive K+ channels in cardiac myocytes: implications for sulfonylurea controversy.

BACKGROUND: Mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel plays a key role in cardioprotection. Hence, a sulfonylurea that does not block mitoK(ATP) channels would be desirable to avoid damage to the heart. Accordingly, we examined the effects of sulfonylureas on the mitoK(ATP) channel and mitochondrial Ca(2+) overload. METHODS: Flavoprotein fluorescence in rabbit ventricular myocytes was measured to assay mitoK(ATP) channel activity. The mitochondrial Ca(2+) concentration was measured by loading cells with rhod-2. RESULTS: The mitoK(ATP) channel opener diazoxide (100 microM) reversibly increased flavoprotein oxidation to 31.8 +/- 4.3% (n = 5) of the maximum value induced by 2,4-dinitrophenol. Glimepiride (10 microM) alone did not oxidize the flavoprotein, and the oxidative effect of diazoxide was unaffected by glimepiride (35.4 +/- 3.2%, n = 5). Similarly, the diazoxide-induced flavoprotein oxidation was unaffected both by gliclazide (10 microM) and by tolbutamide (100 microM). Exposure to ouabain (1 mM) for 30 min produced mitochondrial Ca(2+) overload, and the intensity of rhod-2 fluorescence increased to 197.4 +/- 7.2% of baseline (n = 11). Treatment with diazoxide significantly reduced the ouabain-induced mitochondrial Ca(2+) overload (149.6 +/- 5.1%, n = 11, p < 0.05 versus ouabain alone), and the effect was antagonized by the mitoK(ATP) channel blocker 5-hydroxydecanoate (189.8 +/- 27.8%, n = 5) and glibenclamide (193.1 +/- 7.7%, n = 8). On the contrary, cardioprotective effect of diazoxide was not abolished by glimepiride (141.8 +/- 7.8%, n = 6), gliclazide (139.0 +/- 9.4%, n = 5), and tolbutamide (141.1 +/- 4.5%, n = 7). CONCLUSIONS: Our results indicate that glimepiride, gliclazide, and tolbutamide have no effect on mitoK(ATP) channel, and do not abolish the cardioprotective effects of diazoxide. Therefore, these sulfonylureas, unlike glibenclamide, do not interfere with the cellular pathways that confer cardioprotection.