[Application of computational fluid dynamics in the evaluation of left ventricular function in cardiomyopathies and coronary disease].

Computational fluid dynamics (CFD) is an emerging technology applied in the field of cardiovascular medicine, which can obtain hemodynamic data by simulating the blood flow in the patient's heart for cardiac function assessment and disease diagnosis. Left ventricular function plays a key role in the occurrence and development of cardiomyopathies and coronary disease. CFD can reconstruct the left ventricular anatomic structures of patients to clarify pathophysiologic mechanisms and analyze hemodynamic parameters to evaluate left ventricular function, verify surgical efficacy, and guide surgical strategy, which has a positive effect on achieving early diagnosis and reducing mortality from cardiomyopathies and coronary disease. At present, there are still technical limitations in the large-scale clinical application of CFD, and various solutions are being developed and tested, and further improvement and refinement are needed.

Methicillin-sensitive and methicillin-resistant Staphylococcus aureus strains and their toxin genes in the nostrils of dogs and workers at an animal shelter.

AIMS: Methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively) in the nostrils of dogs and workers at an animal shelter were cultured. Staphylococcal toxin genes were analysed to identify potential health concerns. METHODS AND RESULTS: Samples were obtained from 441 dogs and 9 workers. The respective isolation rates of S. aureus and MRSA were 49·0% (216/441) and 1·6% (7/441) for shelter dogs and 44·4% (4/9) and 33·3% (3/9) for workers, respectively. Isolation of S. aureus in summer (61·9%) and in adult dogs (59·2%) were significantly higher than those in winter (35·8%) and in juvenile dogs (33·3%) (P < 0·001), respectively. The predominant enterotoxin genotypes and combination profiles of S. aureus were (sea, seb, seg, sei, sem, sen, seo, seu) and (sea, sea-seb, and seg-sei-sem-sen-seo-seu), respectively, and 20% of isolates carried food poisoning-associated enterotoxins. The se profiles in shelter dogs were different from those in general pet dogs and their owners. MRSA isolates were identified as SCCmec IV and VII, and they shared se combination profiles of (sec-seg-sei-sel-sem-sen-seo-seu) and (seb-sek-seq). MRSA in this shelter had similar microbiological characteristics as those reported in CA-MRSA ST59 in humans. CONCLUSIONS: Human health-associated bacteria and food poisoning-related toxin genes were identified. Further evaluations of health concerns in animal shelters are necessary. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to focus on se prevalence and MRSA characteristics in an animal shelter in Taiwan. The MRSA characteristics determined in this study were similar to those of CA-MRSA strains isolated from communities in the past, indicating potential health risks in cities.

Heterogeneity and phylogenetic relationships of community-associated methicillin-sensitive/resistant Staphylococcus aureus isolates in healthy dogs, cats and their owners.

AIMS: To investigate the distribution of staphylococcal enterotoxin genes (se) and the molecular features of community-associated methicillin-sensitive/resistant Staphylococcus aureus (CA-MSSA/MRSA) isolates in the nostrils of healthy pets and their owners. METHODS AND RESULTS: A total of 114 Staph. aureus isolates were identified from 1563 nasal swab samples, and CA-MRSA accounted for 20·2% (n = 23) of the total identified isolates. CA-MRSA isolates (91·3%, 21/23) harboured higher percentage of se than did CA-MSSA isolates (58·2%, 53/91) (P < 0·01), and the two highest se profiles of CA-MRSA were seb-sek-seq (42·9%, 9/21) and seb-sek-seq-sep (28·6%, 6/21). Of the MSSAs, 42·8% (39/91) were resistant to at least one antimicrobial drug and 8·8% (8/91) were multidrug resistant (MDR). We identified nine staphylocoagulase (SC) types (I-VIII and X) and three multilocus sequence types (ST59-MRSA-IV/V, ST-239-MRSA-V and ST241-MRSA-V). SC VII (23·4%, 22/94), a staphylococcal food poisoning isolate found mainly in Japan, and ST-59-MRSA-IV/V (85%, 17/20), a widespread CA-MRSA clone found mainly in Taiwan, both were the most predominant types. Phylogenetic analysis together with se and molecular characteristics obtained using pulsed-field gel electrophoresis showed that high levels of antimicrobial resistance and the se-carrying clone ST59-MRSA-IV/V-SC VII were all clustered in genogroup 5. CONCLUSIONS: The CA-MRSA clone of se-carrying-MDR-ST-59-IV/V-SC VII was identified predominantly in this study, and this clone might play a significant role in staphylococcal food poisoning in community settings. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first study focussing on enterotoxin-carrying CA-MRSA/MSSA in pets and their owners, and the results support the future warnings in animal-human bond caused by CA-staphylococci in the commonwealth and the need to take cautions worldwide.

A novel splicing mutation of the CYLD gene in a Taiwanese family with multiple familial trichoepithelioma.

Multiple familial trichoepithelioma (MFT) is an autosomal dominant disease characterized by numerous skin-coloured papules on the central face. Mutations in the CYLD gene, which is also the gene responsible for familial cylindromatosis, have been reported recently. Recent studies indicate that CYLD is a tumour-suppressor gene. The CYLD protein is a negative regulator of the activation of transcription factor nuclear factor-kappaB, and loss of CYLD contributes to oncogenesis. We report a novel splicing mutation (IVS12 + 1 G-->A) in the CYLD gene in a Taiwanese pedigree with MFT, and discuss new developments in treatment options.

Serovar distribution and antimicrobial susceptibility of swine Salmonella isolates from clinically ill pigs in diagnostic submissions from Indiana in the United States.

AIMS: To determine serovar distribution and levels of antimicrobial susceptibility of Salmonella isolated from clinically ill pigs in diagnostic submissions. METHODS AND RESULTS: A total of 197 Salmonella isolates were obtained by the Indiana Animal Disease Diagnostic Laboratory from 2003 to 2005. Minimal inhibitory concentrations (MICs) were determined using the standard microbroth dilution method. The top four serovars identified were Salm. enterica serovar Typhimurium variant Copenhagen, Salm. Derby, Salm. Choleraesuis var. Kunzendorf and Salm. Typhimurium. All isolates were susceptible to the fluoroquinolones tested except that eight isolates were intermediate to difloxacin. The isolates showed a low prevalence of resistance to trimethoprim/sulphadiazine (Sxt), gentamicin (G), ceftiofur (Cf) and cephalothin (Cp) with low MIC(50) value of

Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source.

A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

Involvement of tyrosyl residues in the substrate binding of pigeon liver malic enzyme.

The reactions of pigeon liver malic enzyme (L-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) with tetranitromethane and N-acetylimidazole have been investigated to obtain information about the functional role of tyrosine residues in this enzyme. Incubation of the sulfhydryl-masked enzyme with tetranitromethane or N-acetylimidazole caused a time-dependent loss of all enzymatic activities of this enzyme. The absorption spectra of both the nitrated and acetylated enzyme indicated modification of tyrosine residues. The enzymatic activity of the acetylated enzyme was reversed by hydroxylamine. No amino group modification was observed. Preincubation of the enzyme with dicarboxylate substrate (or inhibitor), nucleotide coenzyme and divalent metal ions protected the enzyme against these reagents. The acetylated enzyme showed different kinetic properties from the native enzyme. The apparent Michaelis constants for malate and oxaloacetate increase by 2-5-fold. The binding between acetylated enzyme and NADPH was not abolished. These results strongly suggest the involvement of tyrosine residues in the dicarboxylic acid binding of malic enzyme.

Modification of essential arginine residues of pigeon liver malic enzyme.

The reaction of pigeon liver malic enzyme (L-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) with dicarbonyl compounds (2,3-butanedione, methylglyoxal, 2,4-pentanedione, and phenylglyoxal) resulted in a rapid loss of its enzymatic activity. The inactivation showed pseudo-first-order kinetics for all the dicarbonyls studied. All the log (pseudo-first-order rate constants) vs. log (dicarbonyl concentration) plots had slopes of near one, indicating approx. 1 : 1 reagent-active site complexes. Butanedione inactivation was reversible and was buffer-dependent. Pentanedione-modified enzyme showed a new absorption peak at 310 nM. NADP could completely protect the enzyme from inactivation. Oxaloacetate, ADP, AMP, NMN and adenosine were also effective in protection. Complete inactivation of the enzyme was accompanied by a loss of about six arginine residues per enzyme monomer. Butanedione-modified enzyme still bound NADPH as shown by fluorescence titration, nor was it binding with NADP impaired as determined by equilibrium gel filtration. The arginine residues, therefore, do not function in the coenzyme binding. However, the binding between the modified enzyme and [14C]malate was significantly decreased. These results led us to conclude that the arginine residues of malic enzyme are involved in the binding of the carboxyl group of substrate malate.

Pentoxifylline Decreases Dialysis Risk in Patients With Advanced Chronic Kidney Disease.

Few studies evaluated the effects of pentoxifylline on hard endpoints in patients with predialysis stage 5 chronic kidney disease (CKD). Thus, we tried to explore the effects of pentoxifylline and its interaction with renin-angiotensin-aldosterone system (RAAS) blockade on the development of endstage renal disease (ESRD) and mortality. This nationwide cohort study retrospectively included patients who had a serum creatinine level of >6 mg/dL and received erythropoiesis-stimulating agents (ESAs) between 2000 and 2010. We analyzed 7,366 pentoxifylline users and 7,366 propensity score-matched nonusers. Using Cox proportional hazard models, pentoxifylline reduced the risks of ESRD and the composite renal outcome but not that of mortality. In terms of the risks of developing ESRD, pentoxifylline alone exerted a comparable beneficial effect to combined therapy with an RAAS inhibitor and greater renoprotection than RAAS inhibitor monotherapy. This study suggests pentoxifylline is efficacious in slowing progression to ESRD in patients with predialysis stage 5 CKD.

Synthesis of 1-benzyl-3-(5'-hydroxymethyl-2'-furyl)indazole analogues as novel antiplatelet agents.

1-Benzyl-3-(5'-hydroxymethyl-2'-furyl)indazole (28, YC-1) was selected as the lead compound for systemic structural modification. After screening for antiplatelet activity, SARs of YC-1 analogues were established. Among these potent active derivatives, compounds 29, 30, 31, 44, and 45 functioned as potent activators of sGC and inhibitors of PDE5 with potency comparable to that of YC-1. In addition, compound 58 was found to be a selective and potent inhibitor of protease-activated receptor type 4 (PAR4)-dependent platelet activation.

Oxidation and cleavage of 3-aminopyridine adenine dinucleotide phosphate with periodate.

Treatment of 3-aminopyridine adenine dinucleotide phosphate with sodium periodate in the neutral pH resulted in oxidation of the ribose linked to 3-aminopyridine and cleavage of the dinucleotide into adenosine- and 3-aminopyridine-containing moieties. Separation of these moieties was afforded by thin-layer chromatography, high-performance liquid chromatography, and fast protein liquid chromatography. From fast atom bombardment mass spectra and nuclear magnetic resonance spectra, the adenosine-containing moiety was identified as 2'-phosphoadenosine 5'-phosphate while the aminopyridine moiety was present in a mixture of the hydrated 3-aminopyridine mononucleotide/nucleoside dialdehyde. Separation of the completely oxidized product by Pharmacia fast protein liquid chromatography gave three major peaks corresponding to 2'-phosphoadenosine 5'-phosphate, 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside, with minor amount of oxidized 3-aminopyridine mononucleotide. Thus the oxidized 3-aminopyridine adenine dinucleotide phosphate was shown to cleave by two pathways: it may either undergo beta-elimination to give 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside; or the phosphodiester linkage may be hydrolyzed to give 2'-phosphoadenosine 5'-phosphate and oxidized 3-aminopyridine mononucleotide. The latter compound may further undergo beta-elimination and eventually give oxidized 3-aminopyridine nucleoside. Hydrolysis could be prevented by storing the sample as lyophilized powder, while beta-elimination was diminished by lowering the storage temperature. We found that the lyophilized powder of oxidized 3-aminopyridine adenine dinucleotide phosphate can be stored at -50 degrees C for several months with minimum decomposition.

[Micellar chromatographic study of amines].

Aqueous solutions of the cationic surfactant, hexadecyl-trimethyl ammonium bromide (CTAB), and the anionic surfactant, sodium dodecylsulfate (SDS) were used as mobile phase in HPLC to study the micellar chromatographic retention mechanism of seven amines and weak organic acids with various distribution coefficients and to study the influence of different pH values mobile phase on the solute retention. An exponential model equation for micellar chromatographic retention mechanism was put forward, which gives a reasonable explanation of the effects of electrostatic interaction and hydrophobic interaction between the solute and the three phases (micelle phase, surfactant modified stationary phase and bulk water phase). This equation can be used to estimate the micellar chromatographic retention pattern of the solute.

Characterization of the tetramer-dimer-monomer equilibrium of the enzymatically active subunits of pigeon liver malic enzyme.

The tetrameric malic enzyme from pigeon liver was reversibly dissociated in the sequence of tetramer-dimer-monomer in an acidic environment (pH 4.5) or when the ionic strength or temperature of the solution was perturbed (0.2 M ammonium sulfate or < 10 degrees C). The dissociated monomer was enzymatically active according to the following criteria: (a) separation and direct activity staining of the monomer in the native gradient polyacrylamide gel, (b) activity staining of the monomer at its pI region in the isoelectric focusing gel, and (c) the enzyme showing lower but definite enzyme activity under conditions where only monomer existed in the solution. The catalytic constant (kcat) and specificity constant (kcat/KmMal) for the monomer were found to be 19 +/- 6 s-1 and 58 x 10(3) s-1.M-1, respectively, only one-seventh and one-seventeenth of those for the tetramer. Different types of interactions are involved in the monomer-monomer and dimer-dimer associations: (a) Two dissociation processes showed different pH dependences. The monomer-monomer interactions involve an amino acid with a side chain pKa value around 5.7, and an amino acid with a side chain pKa value of 7.2 is involved in the dimer-dimer association. (b) Ammonium sulfate up to 0.2 M only affects the monomer-monomer but not the dimer-dimer interactions. The Gibb's free energy, enthalpy, and entropy all have negative values for the above subunits' dissociations. The overall dissociation is an enthalpy-driven process. Association of the subunits to form dimers and tetramers involves salt-bridge, van der Waals, and hydrogen-bonding interactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversible dissociation of the catalytically active subunits of pigeon liver malic enzyme.

The pH-induced reversible dissociation of pigeon liver malic enzyme (EC 1.1.1.40) was studied by combined use of chemical cross-linking and SDS/polyacrylamide-gel electrophoresis. The tetrameric enzyme showed a pH-dependent dissociation in an acidic environment. At pH values above 8.0 most molecules existed as tetramers. The enzyme was gradually dissociated at lower pH. When the pH was below 5.0 most of the enzyme was present as the monomeric forms. Reassociation of the subunits was accomplished by adjusting the pH to neutrality. The dissociation and reassociation were almost instantaneous. No trimer was detected. The pigeon liver malic enzyme was thus shown to have a double-dimer quaternary structure with D2 symmetry. In the presence of substrates, the monomer-dimer-tetramer equilibrium favours the direction of dissociation. Tartronate, an L-malate analogue, was found to be more effective than L-malate in this process. When the monomeric forms were immobilized, the enzyme subunits were found to be fully active in catalysis. A possible arrangement of the four identical subunits of the enzyme molecule is proposed to account for the results obtained in this investigation. The origin of the half-of-the-sites reactivity of pigeon liver malic enzyme is also discussed.

Inhibition of octopus glutathione transferase by Meisenheimer complex analog, S-(2,4,6-trinitrophenyl) glutathione.

The tight binding of Meisenheimer intermediate with octopus digestive gland glutathione transferase was analyzed with 1,3,5-trinitrobenzene, which forms a trapped Meisenheimer complex with glutathione because there is no leaving group at the ipso carbon. By steady-state enzyme kinetic analysis, an inhibition constant of 1.89 +/- 0.17 microM was found for the transient formed, S-(2,4,6-trinitrophenyl) glutathione. The above inhibition constant is 407-fold smaller than the Km value for the substrate (2,4-dinitrochlorobenzene). Thus, S-(2,4,6-trinitrophenyl) glutathione is considered to be a transition-state analog. The tight binding of this inhibitor to the enzyme provides an explanation for the involvement of the biological binding effect on the rate enhancement in the glutathione transferase-catalyzed SNAr mechanism.

Inhibitory effect of magnesium ion on the human placental alkaline phosphatase-catalyzed reaction in a reverse micellar system.

Human placental alkaline phosphatase is a membrane-anchored protein. Entrapping the enzyme into a reverse micellar vesicle mimics the in vivo conditions and allows examination of the properties of the enzyme. Placental alkaline phosphatase is enzymatically active in Aerosol-OT/isooctane reverse micelles. Substantially different kinetic behavior of the enzyme has been observed in aqueous or reverse micellar systems. In aqueous solution, Mg2+ is a nonessential activator of the enzyme. In the experiments described in the present report Mg2+ was found to be an inhibitor for the enzyme in reverse micelles. This inhibition is presumably due to a time-dependent conformational change of the enzyme molecule, which resulted in a curvature in the recorder tracings of the enzyme assays. The Mg2+-induced conformational change of the enzyme was completely prevented by phosphate and partially reserved by EDTA. High concentrations of Zn2+ also strongly inhibited enzyme activity in both aqueous and reverse micellar solvent systems, presumably by occupying the Mg2+ (M3) site of the enzyme. However, binding of Zn2+ at the M3 site did not cause conformational change of the enzyme and the enzyme assay tracing was linear. The M3 site of the enzyme is proposed to have a modulatory role in vivo using magnesium ion as the modulator.

Mechanism of pigeon liver malic enzyme: modification of essential carboxyl groups.

The maximum velocity of the reaction catalyzed by the pigeon liver malic enzyme depends on the ionization of a functional group of pKa 6.7. This pKa value is independent of temperature within the range 30 degrees-49 degrees C, suggesting the ionization of a carboxyl group. The enzyme activity is inactivated by N-ethyl-5-phenylisoxazolium-3'-sulfonate (Woodward reagent K) at pH 6.0 and 25 degrees C. N-Methylhydroxamine regenerates the enzymatic activity whereas glycine ethyl ester does not. The addition of Mn2+, NADP+, and L-malate to the incubation mixture decreases the inactivation rate, suggesting that the reaction takes place in the active center. The binding capacities of the modified enzyme with NADP+, L-malate, pyruvate, and Mn2+ are not impaired. The kinetic and chemical evidence indicates that the inactivation is due to the modification of a carboxyl group which may be from glutamyl or aspartyl residues of the enzyme. This carboxyl group might function as a general acid-base catalyst. A detailed mechanism in terms of the exact amino acid residues involved is proposed.

Single-Mode Operation and Frequency Doubling of Fiber-Coupled Diode Butt-Coupling-Pumped Nd:YVO(4) Lasers.

We present a simple way to achieve single-frequency operation by using a fiber-coupled diode butt-coupling-pumped Nd:YVO(4) laser in a flat-flat cavity. Single-mode outputs of 620 and 260 mW for fundamental and second-harmonic wavelengths were obtained when the laser was pumped by an 1100-mW fiber-coupled laser diode. Experimental results show that thermal effects provide not only a stable resonator with a good overlap of laser mode and pump size but also enhance single-frequency performance.

Reverse micelles as life-mimicking systems.

In this review, we attempt to demonstrate that reverse micelles are simple artificial systems that mimic many life systems from cell division to the creation of an enzyme catalytic mechanism. For a membranous enzyme like placental alkaline phosphatase, the kinetic properties observed in reverse micelles might represent those found under physiological conditions. The reverse micellar system, consisting of a positively charged surfactant, mimics a detoxification enzyme glutathione transferase. We propose a novel island-in-oil-lake reverse micellar model for the glutathione transferase that can account for almost all the catalytic properties of this enzyme. Reverse micelles may provide an excellent model system in investigating the reaction mechanism of other detoxification enzymes.