Evaluation of Antibacterial Activity of Selenium Nanoparticles against Food-Borne Pathogens.

Selenium is an essential micronutrient for all mammals and plays an important role in maintaining human physiological functions. Selenium nanoparticles (SeNPs) have been shown to demonstrate antioxidant and antimicrobial activity. The objective of this study was to explore whether SeNPs have the potential to be used as food preservatives with which to reduce food spoilage.

Ionic Liquids as Protein Crystallization Additives.

Among its attributes, the mythical philosopher's stone is supposedly capable of turning base metals to gold or silver. In an analogous fashion, we are finding that protein crystallization optimization using ionic liquids (ILs) often results in the conversion of base protein precipitate to crystals. Recombinant inorganic pyrophosphatases (8 of the 11 proteins) from pathogenic bacteria as well as several other proteins were tested for optimization by 23 ILs, plus a dHO control, at IL concentrations of 0.

Dielectrophoresis-Based Positioning of Carbon Nanotubes for Wafer-Scale Fabrication of Carbon Nanotube Devices.

In this paper, we report the wafer-scale fabrication of carbon nanotube field-effect transistors (CNTFETs) with the dielectrophoresis (DEP) method. Semiconducting carbon nanotubes (CNTs) were positioned as the active channel material in the fabrication of carbon nanotube field-effect transistors (CNTFETs) with dielectrophoresis (DEP). The drain-source current (I) was measured as a function of the drain-source voltage (V) and gate-source voltage (V) from each CNTFET on the fabricated wafer.

Enhanced Silver Nanoparticle Synthesis by Transformed with Metallothionein Gene.

In this study, the metallothionein gene of () was assembled by polymerase chain reaction (PCR), inserted into pUC19 vector, and further transformed into ) DH5α cells. The capacity of these recombinant DH5α cells to synthesize silver nanoparticles was examined. Our results demonstrated that the expression of metallothionein in promoted the bacterial tolerance to metal ions and increased yield of silver nanoparticle synthesis.

Trace fluorescent labeling for protein crystallization.

Fluorescence can be a powerful tool to aid in the crystallization of proteins. In the trace-labeling approach, the protein is covalently derivatized with a high-quantum-yield visible-wavelength fluorescent probe. The final probe concentration typically labels ≤0.

Triadin/Junctin double null mouse reveals a differential role for Triadin and Junctin in anchoring CASQ to the jSR and regulating Ca(2+) homeostasis.

Triadin (Tdn) and Junctin (Jct) are structurally related transmembrane proteins thought to be key mediators of structural and functional interactions between calsequestrin (CASQ) and ryanodine receptor (RyRs) at the junctional sarcoplasmic reticulum (jSR). However, the specific contribution of each protein to the jSR architecture and to excitation-contraction (e-c) coupling has not been fully established. Here, using mouse models lacking either Tdn (Tdn-null), Jct (Jct-null) or both (Tdn/Jct-null), we identify Tdn as the main component of periodically located anchors connecting CASQ to the RyR-bearing jSR membrane.

Ablation of junctin or triadin is associated with increased cardiac injury following ischaemia/reperfusion.

Aims: Junctin and triadin are calsequestrin-binding proteins that regulate sarcoplasmic reticulum (SR) Ca(2+) release by interacting with the ryanodine receptor. The levels of these proteins are significantly down-regulated in failing human hearts. However, the significance of such decreases is currently unknown.

The human phospholamban Arg14-deletion mutant localizes to plasma membrane and interacts with the Na/K-ATPase.

Depressed Ca-handling in cardiomyocytes is frequently attributed to impaired sarcoplasmic reticulum (SR) function in human and experimental heart failure. Phospholamban (PLN) is a key regulator of SR and cardiac function, and PLN mutations in humans have been associated with dilated cardiomyopathy (DCM). We previously reported the deletion of the highly conserved amino acid residue arginine 14 (nucleic acids 39, 40 and 41) in DCM patients.

Dual role of junctin in the regulation of ryanodine receptors and calcium release in cardiac ventricular myocytes.

Junctin, a 26 kDa intra-sarcoplasmic reticulum (SR) protein, forms a quaternary complex with triadin, calsequestrin and the ryanodine receptor (RyR) at the junctional SR membrane. The physiological role for junctin in the luminal regulation of RyR Ca(2+) release remains unresolved, but it appears to be essential for proper cardiac function since ablation of junctin results in increased ventricular automaticity. Given that the junctin levels are severely reduced in human failing hearts, we performed an in-depth study of the mechanisms affecting intracellular Ca(2+) homeostasis in junctin-deficient cardiomyocytes.

Small heat shock protein 20 interacts with protein phosphatase-1 and enhances sarcoplasmic reticulum calcium cycling.

Background: Heat shock proteins (Hsp) are known to enhance cell survival under various stress conditions. In the heart, the small Hsp20 has emerged as a key mediator of protection against apoptosis, remodeling, and ischemia/reperfusion injury. Moreover, Hsp20 has been implicated in modulation of cardiac contractility ex vivo.

Partial downregulation of junctin enhances cardiac calcium cycling without eliciting ventricular arrhythmias in mice.

Human failing hearts exhibit significant decreases in junctin expression levels with almost nondetectable levels, which may be associated with premature death, induced by lethal cardiac arrhythmias, based on mouse models. However, the specific contribution of junctin to the delayed afterdepolarizations has been difficult to delineate in the phase of increased Na(+)-Ca(2+) exchanger activity accompanying junctin ablation. Thus we characterized the heterozygous junctin-deficient hearts, which expressed 54% of junctin levels and similar increases in Na(+)-Ca(2+) exchanger activity, as the null model.

Endoplasmic reticulum-mitochondria crosstalk in NIX-mediated murine cell death.

Transcriptional upregulation of the proapoptotic BCL2 family protein NIX limits red blood cell formation and can cause heart failure by inducing cell death, but the requisite molecular events are poorly defined. Here, we show complementary mechanisms for NIX-mediated cell death involving direct and ER/sarcoplasmic reticulum-mediated (ER/SR-mediated) mitochondria disruption. Endogenous cardiac NIX and recombinant NIX localize both to the mitochondria and to the ER/SR.

Regulatory roles of junctin in sarcoplasmic reticulum calcium cycling and myocardial function.

Junctin (JCN), a 26-kd sarcoplasmic reticulum (SR) transmembrane protein, forms a quaternary protein complex with the ryanodine receptor, calsequestrin, and triadin in the SR lumen of cardiac muscle. Within this complex, calsequestrin, triadin, and JCN appear to be critical for normal regulation of ryanodine receptor-mediated calcium (Ca) release. Junctin and triadin exhibit 60% to 70% amino acid homology in their transmembrane domains, including repeated KEKE motifs important for macromolecular protein-protein interactions within their SR luminal tails.

Sarcoplasmic reticulum calcium overloading in junctin deficiency enhances cardiac contractility but increases ventricular automaticity.

Background: Abnormal sarcoplasmic reticulum calcium (Ca) cycling is increasingly recognized as an important mechanism for increased ventricular automaticity that leads to lethal ventricular arrhythmias. Previous studies have linked lethal familial arrhythmogenic disorders to mutations in the ryanodine receptor and calsequestrin genes, which interact with junctin and triadin to form a macromolecular Ca-signaling complex. The essential physiological effects of junctin and its potential regulatory roles in sarcoplasmic reticulum Ca cycling and Ca-dependent cardiac functions, such as myocyte contractility and automaticity, are unknown.

Junctin is a prominent regulator of contractility in cardiomyocytes.

Junctin is one of the components of the ryanodine receptor Ca release channel complex in sarcoplasmic reticulum. To determine the role of acute alteration of junctin protein levels on cardiomyocyte contractility, we used adenoviral-mediated gene transfer techniques in adult rat cardiomyocytes. Acute downregulation of junctin by 40% resulted in significant increases in cell shortening, rate of contraction (+dL/dt), and rate of relaxation (-dL/dt).

Small heat-shock protein Hsp20 attenuates beta-agonist-mediated cardiac remodeling through apoptosis signal-regulating kinase 1.

Chronic stimulation of the beta-adrenergic neurohormonal axis contributes to the progression of heart failure and mortality in animal models and human patients. In cardiomyocytes, activation of the beta-adrenergic pathway has been shown to result in transiently increased expression of a cardiac small heat-shock protein Hsp20. The present study shows that cardiac overexpression (10-fold) of Hsp20 may protect the heart against beta-agonist-induced cardiac remodeling, associated with isoproterenol (50 mug/g per day) infusion for 14 days.

The presence of Lys27 instead of Asn27 in human phospholamban promotes sarcoplasmic reticulum Ca2+-ATPase superinhibition and cardiac remodeling.

Background: Phospholamban (PLN) is an inhibitor of the Ca2+ affinity of sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2). The amino acid sequence of PLN is highly conserved, and although all species contain asparagine (Asn), human PLN is unique in containing lysine (Lys) at amino acid 27.

Methods And Results: Human PLN was introduced in the null background.

Novel cardioprotective role of a small heat-shock protein, Hsp20, against ischemia/reperfusion injury.

Background: Heat-shock proteins (Hsps) have been shown to render cardioprotection from stress-induced injury; however, little is known about the role of another small heat-shock protein, Hsp20, which regulates activities of vasodilation and platelet aggregation, in cardioprotection against ischemia injury. We recently reported that increased expression of Hsp20 in cardiomyocytes was associated with improved contraction and protection against beta-agonist-induced apoptosis.

Methods And Results: To investigate whether overexpression of Hsp20 exerts protective effects in both ex vivo and in vivo ischemia/reperfusion (I/R) injury, we generated a transgenic (TG) mouse model with cardiac-specific overexpression of Hsp20 (10-fold).

Small heat-shock protein Hsp20 phosphorylation inhibits beta-agonist-induced cardiac apoptosis.

Activation of the sympathetic nervous system is a common compensatory feature in heart failure, but sustained beta-adrenergic activation induces cardiomyocyte death, leading to cardiac remodeling and dysfunction. In mouse cardiomyocytes, we recently reported that prolonged exposure to beta-agonists is associated with transient increases in expression and phosphorylation of a small heat-shock protein, Hsp20. To determine the functional significance of Hsp20, we overexpressed this protein and its constitutively phosphorylated (S16D) or nonphosphorylated (S16A) mutant in adult rat cardiomyocytes.