Persistence of Caliciviruses in Artificially Contaminated Oysters during Depuration

The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters.     

Transient receptor potential channels in Alzheimer's disease

Cognitive impairment and emotional disturbances in Alzheimer's disease (AD) result from the degeneration of synapses and neuronal death in the limbic system and associated regions of the cerebral cortex. An alteration in the proteolytic processing of the amyloid precursor protein (APP) results in increased production and accumulation of amyloid beta-peptide (Abeta) in the brain. Abeta can render neurons vulnerable to excitotoxicity and apoptosis by disruption of cellular Ca(2+) homeostasis and neurotoxic factors including reactive oxygen species (ROS), nitric oxide (NO), and cytokines. Many lines of evidence have suggested that transient receptor potential (TRP) channels consisting of six main subfamilies termed the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and TRPA (ankyrin) are involved in Ca(2+) homeostasis disruption. Thus, emerging evidence of the pathophysiological role of TRP channels has yielded promising candidates for molecular entities mediating Ca(2+) homeostasis disruption in AD. In this review, we focus on the TRP channels in AD and highlight some TRP "suspects" for which a role in AD can be anticipated. An understanding of the involvement of TRP channels in AD may lead to the development of new target therapies.     

IKr and IKs remodeling differentially affects QT interval prolongation and dynamic adaptation to heart rate acceleration in bradycardic rabbits

Bradycardic ventricular electrical remodeling predisposes to lethal tachyarrhythmias. We investigated the early temporal sequence and reversibility of electrical remodeling in a rabbit complete heart block model subjected to bradycardic ventricular pacing for either 2 or 8 days, with a third group of animals undergoing 8 days of bradycardic pacing followed by 8 days of physiological-rate pacing. At specified time points after complete heart block induction and pacing initiation, steady-state QT interval measurements and variability as well as dynamic QT interval adaptation to abrupt heart rate acceleration were assessed in the absence and presence of isoproterenol. Rapidly (I(Kr)) and slowly (I(Ks)) activating delayed rectifier repolarizing K(+) tail current densities were evaluated using whole cell patch clamp in isolated right ventricular myocytes. Steady-state QT interval prolongation at both 2 and 8 days was associated with moderate I(Kr) reduction. I(Ks) downregulation was apparent by day 2 but more profound at day 8. Dynamic QT interval adaptation was impaired under baseline conditions at day 8 but only during isoproterenol administration at day 2. Both in vivo and cellular manifestations of remodeling reverted toward control values after 8 days of physiological-rate pacing. In conclusion, in this bradycardic model, I(Ks) downregulation 1) proceeds more gradually but more extensively than that of I(Kr) and 2) is most prominently associated with impaired dynamic QT interval adaptation to heart rate acceleration. Isoproterenol blunts the dynamic QT interval response in animals with partially downregulated I(Ks), consistent with stress-related phenomena in known I(Ks)-impaired states. Relative early sparing of I(Ks) could explain the delay in the onset of lethal tachyarrhythmia predisposition in bradycardic electrical remodeling. Reversibility of remodeling supports the potential utility of preventive pacing intervention soon after bradycardia onset.     

PTEN reduces cuff-induced neointima formation and proinflammatory cytokines

An inflammatory response followed by vascular injury plays an important role in neointima formation and development of atherosclerotic lesions, which are in part mediated by proinflammatory cytokines. Using a cuff injury model, we examined the effects of adenovirus-mediated overexpression of phosphatase and tensin homology deleted on chromosome 10 (PTEN) on neointima formation and the proinflammatory response. A cuff was placed around the femoral artery, and adenovirus expressing human PTEN type 1 (AdPTEN) or Escherichia coli beta-galactosidase (AdLacZ) was injected between the cuff and the adventitia. After 14 days, the arteries were examined histopathologically and by Western blotting. The significant reduction of neointima formation by AdPTEN compared with AdLacZ was accompanied by reduced cell proliferation and increased adventitial cell apoptosis. AdPTEN also reduced expression of phosphorylated I kappa B-alpha, but not nonphosphorylated I kappa B-alpha. Western blotting revealed that AdPTEN reduced the cuff injury-induced expression levels of monocyte chemoattractant protein-1, TNF-alpha, and IL-1 beta and their expression in all layers of the arterial wall. In contrast, cuff-induced macrophage invasion, which was also inhibited by AdPTEN, was detected only at the intimal surface and in the adventitia. In cultured vascular smooth muscle cells, PTEN directly inhibited ANG II-induced monocyte chemoattractant protein-1 expression as quantified by real-time PCR and Western blotting. Our results suggest that overexpression of PTEN reduces neointima formation, possibly in part through inhibition of the inflammatory response by macrophage invasion and proinflammatory cytokine expression.     

One set system for the synthesis and purification of glycosaminoglycan oligosaccharides reconstructed using a hyaluronidase‐immobilized column

Using the transglycosylation reaction as a reverse reaction for the hydrolysis of hyaluronidase, new artificial oligosaccharides may be synthesized by reconstructing natural glycosaminoglycans (GAGs) according to preliminary planned arrangements. However, as some problems have been associated with the method, including the low yields of reaction products and complicated processes of separation and purification, improvements in this method were investigated. Transglycosylation reactions were carried out using bovine testicular hyaluronidase‐immobilized resin packed in a column. For the transglycosylation reaction, pyridylaminated (PA) GAG hexasaccharides, which were the minimum size for hydrolysis sensitivity and the transglycosylation reaction, were used as acceptors, whereas large size GAGs were used as donors. The reaction mixture was pooled after incubation in the hyaluronidase‐immobilized resin column and was then introduced into continuously joined HPLC columns constructed from three steps: the first step of ion‐exchange HPLC for concentrating newly synthesized GAG oligosaccharides as reaction products, the second step of reverse phase HPLC for separating PA oligosaccharides from non‐PA oligosaccharides, and the third step of size fractionation HPLC for fractionating newly synthesized oligosaccharides. Newly synthesized oligosaccharides were obtained by one complete cycle of the transglycosylation reaction and separation. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 189–196, 2014.     

Contribution of calumin to embryogenesis through participation in the endoplasmic reticulum-associated degradation activity

Calumin is an endoplasmic reticulum (ER)-transmembrane protein, and little is known about its physiological roles. Here we showed that calumin homozygous mutant embryos die at embryonic days (E) 10.5−11.5. At mid-gestation, calumin was expressed predominantly in the yolk sac. Apoptosis was enhanced in calumin homozygous mutant yolk sacs at E9.5, pointing to a possible link to the embryonic lethality. Calumin co-immunoprecipitated with ERAD components such as p97, BIP, derlin-1, derlin-2 and VIMP, suggesting its involvement in ERAD. Indeed, calumin knockdown in HEK 293 cells resulted in ERAD being less efficient, as demonstrated by attenuation in both degradations of a misfolded α1-antitrypsin variant and the ER-to-cytosol dislocation of cholera toxin A1 subunit. In calumin homozygous mutant yolk sac endoderm cells, ER stress-associated alterations were observed, including lipid droplet accumulation, fragmentation of the ER and dissociation of ribosomes from the ER. In this context, the ER-overload response, assumed to be cytoprotective, was also triggered in the mutant endoderm cells, but seemed to fully counteract the excessive ER stress generated due to defective ERAD. Taken together, our findings suggested that calumin serves to maintain the yolk sac integrity through participation in the ERAD activity, contributing to embryonic development.     

A novel rabbit model of variably compensated complete heart block.

Complete heart block (CHB) provides a useful substrate for study of bradycardia-dependent ventricular arrhythmias and cardiac function. Existing CHB animal models are limited by surgical recovery time and reliance on intrinsic escape rhythms. We describe a novel closed-chest rabbit model of CHB involving transcatheter radiofrequency (RF) atrioventricular (AV) node ablation and ventricular rate control with chronic transvenous pacing. Permanent CHB was achieved in 34 of 38 attempts overall. Procedural mortality due to cardiac tamponade (n = 2), airway complications (n = 2), and unknown causes (n = 5) occurred in nine animals. Survivors with CHB (n = 28) were maintained for < or = 22 days, during which there were three late deaths related to infection (n = 1) or respiratory distress (n = 2). None of the survivors with CHB showed recovery of AV conduction or pacemaker capture loss during chronic ventricular pacing at about one-half normal sinus rates, and 25 animals surviving to death showed no overt signs of hemodynamic compromise such as lethargy, poor feeding, or respiratory distress. This approach provides a reproducible nonsurgical CHB model with adjustable ventricular rate control.