Characterization of Magnesium Sulfate as an Antiarrhythmic Agent

Background

Recently, intravenous magnesium therapy has been used for the treatment of ventricular arrhythmias, but data to establish a causal link between the electrophysiological properties and the antiarrhythmic actions are lacking.

Methods and Results

The acute antiarrhythmic effect of magnesium sulfate was assessed using epinephrine-, digitalis-, and coronary ligation-induced canine ventricular arrhythmia models. The intravenous administration of magnesium sulfate (100 mg/kg) reduced the incidence of the ventricular arrhythmias of all models. The antiarrhythmic effect on the epinephrine-induced arrhythmia was potent and long-lasting, while those on the other arrhythmia models were weak and transient. The direct cardiovascular effects were assessed using the canine isolated, blood-perfused sinus node, papillary muscle, and atrioventricular node preparations. The intracoronary administration of magnesium sulfate (0.1–30 mg) suppressed sinoatrial automaticity and ventricular contraction, while it increased atrio-His and His-ventricular conduction time, coronary blood flow, and the duration of monophasic action potential in a dose-dependent manner. The effects on His-ventricular conduction and monophasic action potential duration were less potent compared with the other cardiovascular effects.

Conclusion

These results suggest that magnesium sulfate possesses multiple electrophysiological properties and that the effects related to the calcium channel inhibition may be the most relevant for the antiarrhythmic actions.

P5718Effects of the fluoroquinolones moxifloxacin and levofloxacin on the QT subintervals: sex differences in ventricular repolarization

Background

The effects of medicines affecting cardiac repolarization can be further evaluated by assessing the balance of inward and outward currents. These can be detected in the ECG by analysing the QT subintervals. Pure hERG potassium channel block was shown to prolong both early repolarization (J-Tpeak) and late repolarization (Tpeak-Tend), whereas multichannel blockers may shorten or have no effect on J-Tpeak.

The gender dependency of ventricular repolarization is also well known. Recently, Matsukura indicated that moxifloxacin significantly increased J-Tpeak and Tpeak-Tend and females in their study were more sensitive than males to the drug-induced J-Tpeak prolongation and QTcF.

Purpose

The purpose of the present study is to use data from two Thorough QT (TQT) studies to characterize the differences in depolarization (QRS), early repolarization (J-Tpeak), and late repolarization (Tpeak-Tend) between moxifloxacin and levofloxacin and further define the sex differences in QTc and subintervals.

Methods

Data from two TQT studies were used to further investigate the impact of moxifloxacin (400 mg) and levofloxacin (1000 and 1500 mg) on QT subintervals using validated algorithms for measurement of QRS, J-Tpeak and Tpeak–Tend intervals. Concentration-effect analyses were performed to establish a potential relationship between the ECG effects and the concentrations of the two fluoroquinolones as typically males and females also show differences in plasma concentrations due to differences in body weight.

Results

The relationships between moxifloxacin and levofloxacin plasma concentrations and their respective predicted ΔΔQTcF, ΔΔQRS, ΔΔJ-Tpeakc and ΔΔTpeak-Tend values are shown in Fig 1.

The plasma concentrations were higher for females than males in both drugs.

Moxifloxacin was shown to be a more potent prolonger of QTcF and had a pronounced effect on J-Tpeakc, consistent with its effects on both IKr and IKs channels while levofloxacin had little effect on J-Tpeakc. For moxifloxacin, the concentration-effect modelling showed a greater effect for females on QTcF and J-Tpeakc while for levofloxacin the inverse was true. Based on the assumption that repolarization reserve of females relies to a greater extent on IKs channels it would be reasonable to assume that they are more affected by a medicine that blocks IKs in addition to IKr.

Figure 1

Conclusions

This study showed that levofloxacin elicited a smaller ΔΔQTcF and ΔΔJ-Tpeakc prolongation when compared to moxifloxacin. The results of this study also showed a different pattern of sex difference in repolarization after administration of both drugs. which may suggest a difference in expression of IKs and possibly IKr channels.

Histopathological Features of Mycobacterium chelonae Infection in Two Farmed Japanese Pufferfish (Takifugu rubripes)

Granulomatous lesions were observed in the swim bladder, kidney, spleen and gills of two farmed Japanese pufferfish (Takifugu rubripes) infected with Mycobacterium chelonae. Three types of lesions were noted: unencapsulated clusters of epithelioid cells without central necrosis (type 1), encapsulated granulomas without central necrosis (type 2) and encapsulated granulomas with central necrosis (type 3). Type 3 lesions occurred most frequently in the swim bladder, while type 1 and type 2 lesions occurred frequently in the kidney and spleen, and the gills exhibited mostly type 1 lesions. This suggests that the lesions in the swim bladder were more fully developed than those occurring elsewhere and that the swim bladder may be more susceptible to infection with M. chelonae. This is the first report describing the histopathological features of M. chelonae infection in Tetraodontidae.

Development of Gating Foils To Inhibit Ion Feedback Using FPC Production Techniques

Positive ion feedback from a gas amplification device to the drift region of the Time Projection Chamber for the ILC can deteriorate the position resolution. In order to inhibit the feedback ions, MPGD-based gating foils having good electron transmission have been developed to be used instead of the conventional wire gate. The gating foil needs to control the electric field locally in opening or closing the gate. The gating foil with a GEM (gas electron multiplier)-like structure has larger holes and smaller thickness than standard GEMs for gas amplification. It is known that the foil transmits over 80 % of electrons and blocks ions almost completely. We have developed the gating foils using flexible printed circuit (FPC) production techniques including an improved single-mask process. In this paper, we report on the production technique of 335 μm pitch, 12.5 μm thick gating foil with 80 % transmittance of electrons in ILC conditions.

MR Imaging Features of the Cerebellum in Adult-Onset Neuronal Intranuclear Inclusion Disease: 8 Cases

Neuronal intranuclear inclusion disease is a neurodegenerative disorder pathologically characterized by eosinophilic hyaline intranuclear inclusions. A high-intensity signal along the corticomedullary junction on DWI has been described as a specific MR imaging finding of the cerebrum in neuronal intranuclear inclusion disease. However, MR imaging findings of the cerebellum in neuronal intranuclear inclusion disease have not been fully evaluated. Here, we review MR imaging findings of the cerebellum in a series of 8 patients with pathologically confirmed neuronal intranuclear inclusion disease. The MR imaging results showed cerebellar atrophy (8/8 patients) and high-intensity signal on FLAIR images in the medial part of the cerebellar hemisphere right beside the vermis (the "paravermal area") (6/8) and in the middle cerebellar peduncle (4/8). The paravermal abnormal signals had a characteristic distribution, and they could be an indicator of the diagnosis of neuronal intranuclear inclusion disease even when using the results of past MR imaging examinations in which DWI findings were not examined.

Characterization of micron-size hydrogen clusters using Mie scattering

Hydrogen clusters with diameters of a few micrometer range, composed of 10^8-10 hydrogen molecules, have been produced for the first time in an expansion of supercooled, high-pressure hydrogen gas into a vacuum through a conical nozzle connected to a cryogenic pulsed solenoid valve. The size distribution of the clusters has been evaluated by measuring the angular distribution of laser light scattered from the clusters. The data were analyzed based on the Mie scattering theory combined with the Tikhonov regularization method including the instrumental functions, the validity of which was assessed by performing a calibration study using a reference target consisting of standard micro-particles with two different sizes. The size distribution of the clusters was found discrete peaked at 0.33 ± 0.03, 0.65 ± 0.05, 0.81 ± 0.06, 1.40 ± 0.06 and 2.00 ± 0.13 µm in diameter. The highly reproducible and impurity-free nature of the micron-size hydrogen clusters can be a promising target for laser-driven multi-MeV proton sources with the currently available high power lasers.

Hashimoto's disease is a frequent comorbidity and an exacerbating factor of chronic spontaneous urticaria

BACKGROUND

The precise pathogenesis of chronic spontaneous urticaria (CSU) remains unknown. However, an important association between CSU and autoimmune disorders such as Hashimoto's disease (HD) has been reported. We investigated the frequency of HD as a comorbidity of CSU and the prevalence rate of autoreactivity among CSU patients with HD.

PATIENTS AND METHODS

The presence of thyroid autoantibodies and the levels of thyroid hormones were examined in 40 CSU patients who showed urticaria symptoms for >4 weeks. Patients who were diagnosed with HD, including subclinical ones, and were in need of treatment received thyroid therapy, and the changes in their urticarial symptoms were observed. An autologous serum skin test (ASST) was also performed to examine the relation of CSU with autoreactivity.

RESULTS

Eleven of the 40 CSU patients were diagnosed with HD, and 4 of the 5 patients who received and completed thyroid therapy showed considerable remission of urticarial symptoms during and after treatment. In addition, the rate of positive ASST results tended to be higher in CSU patients with HD (5 of 7) than in those without HD (2 of 6).

CONCLUSIONS

The comorbidity rate of HD in CSU patients was high, and such patients tended to have a positive ASST. Thyroid therapy in CSU patients with HD can lead to a considerable remission of urticarial symptoms, which may suggest that HD is possibly involved in the aetiology of CSU, or is at least a potential exacerbating factor for CSU.

Overexpression and Purification of Asparagine Synthetase fromEscherichia coli

Overexpression of the asnA gene from Escherichia coli K-12 coding for asparagine synthetase (EC 6.3.1.1) was achieved with a plasmid, pUNAd37, a derivative of pUC18, in E. coli. The plasmid was constructed by optimizing a DNA sequence between the promoter and the ribosome binding region. The enzyme, comprising ca. 15% of the total soluble protein in the E. coli cell, was readily purified to apparent homogeneity by DEAE-Cellulofine and Blue-Cellulofine column chromatographies. The amino-terminal sequence, amino acid composition, and molecular weight of the purified protein agreed with the predicted values based on the DNA sequence of the gene. Furthermore the native molecular weight measured by gel filtration confirmed that asparagine synthetase exists as a dimer of identical subunits.

Quantitative evaluation of bone development of the distal phalanx of the cow hind limb using computed tomography

Computed tomography (CT) was performed on 400 claws (200 inner and 200 outer claws) of 100 pairs of bovine hind limbs to investigate the etiological theory that an exacerbating factor for ulceration is exostosis of the tuberculum flexorium within the distal phalanx. A variety of morphological changes of the tuberculum flexorium of bovine hind limb claws was visualized by 3-dimensional CT, and the geometry of these claws suggested a growth pattern of bone development with respect to the assumed daily loading patterns. This growth occurs initially at the abaxial caudal aspect of the distal phalanx and is followed by horizontal progression toward the axial aspect. The length of downward bone development on the solar face of the distal phalanx was 2.73±1.32 mm in the outer claws, significantly greater than in the inner claws (2.38±0.96 mm). Ratios of downward (vertical) bone development to the thickness of the subcutis and the corium (VerBD ratios) did not differ between the outer and inner claws (36.7 vs. 38.3%, respectively). Ratios of horizontal bone development to the axial-to-abaxial line of the tuberculum flexorium (HorBD ratios) were approximately 60% for both outer and inner claws. These quantitative measures regarding horizontal and vertical bone development within the distal phalanx were positively correlated with age and VerBD ratios (r=0.53 and r=0.36 for the inner and outer claws, respectively). Correlations between claw width of the outer claw and length of vertical bone development (r=0.43), the HorBD ratio (r=0.51), and the VerBD ratio (r=0.42) suggested that the relative size difference between the inner and outer claws enhances bone development in the outer claw. Correlation coefficients between VerBD and HorBD ratios (r=0.52 and 0.63 for the inner and outer claws, respectively) suggested that horizontal and vertical bone development occurs as a synchronized process within the tuberculum flexorium. This age-related progress of bone development within the tuberculum flexorium is associated with increased exposure to several exacerbating factors and the laminitic process.

Production of prenylated flavonoids in tomato fruits expressing a prenyltransferase gene from Streptomyces coelicolor A3(2)

Flavonoids are natural compounds found in many plants, including the important fruit crop, tomato. Prenylated flavonoids consist of a large group of compounds, which often exhibit antitumour, antibacterial and/or anti-androgen activities. In this study, we engineered the biosynthesis of prenylated flavonoids using a Streptomyces prenyltransferase HypSc (SCO7190) possessing broad-range substrate specificity, in tomato as a host plant. LC/MS/MS analysis demonstrated the generation of 3'-dimethylallyl naringenin in tomato fruits when recombinant HypSc protein was targeted to the plastids, whereas the recombinant protein hardly produced this compound in vitro. This is the first report confirming the accumulation of a prenylated flavonoid using a bacterial prenyltransferase in transgenic plants, and our results suggest that the product specificities of prenyltransferases can be significantly influenced by the host plant.

High temporal and spatial quality petawatt-class Ti:sapphire chirped-pulse amplification laser system

Optical parametric chirped-pulse amplification (OPCPA) operation with low gain by seeding with high-energy, clean pulses is shown to significantly improve the contrast to better than 10(-10) to 10(-11) in a high-intensity Ti:sapphire laser system that is based on chirped-pulse amplification. In addition to the high-contrast broadband, high-energy output from the final amplifier is achieved with a flat-topped spatial profile of filling factor near 77%. This is the result of pump beam spatial profile homogenization with diffractive optical elements. Final pulse energies exceed 30 J, indicating capability for reaching peak powers in excess of 500 TW.

Electron optical injection with head-on and countercrossing colliding laser pulses

A high stability electron bunch is generated by laser wakefield acceleration with the help of a colliding laser pulse. The wakefield is generated by a laser pulse; the second laser pulse collides with the first pulse at 180 degrees and at 135 degrees realizing optical injection of an electron bunch. The electron bunch has high stability and high reproducibility compared with single pulse electron generation. In the case of 180 degrees collision, special measures have been taken to prevent damage. In the case of 135 degrees collision, since the second pulse is countercrossing, it cannot damage the laser system.

Long-term blockade of L/N-type Ca(2+) channels by cilnidipine ameliorates repolarization abnormality of the canine hypertrophied heart

BACKGROUND AND PURPOSE

The heart of the canine model of chronic atrioventricular block is known to have a ventricular electrical remodelling, which mimics the pathophysiology of long QT syndrome. Using this model, we explored a new pharmacological therapeutic strategy for the prevention of cardiac sudden death.

EXPERIMENTAL APPROACH

The L-type Ca(2+) channel blocker amlodipine (2.5 mg.day(-1)), L/N-type Ca(2+) channel blocker cilnidipine (5 mg.day(-1)), or the angiotensin II receptor blocker candesartan (12 mg.day(-1)) was administered orally to the dogs with chronic atrioventricular block for 4 weeks. Electropharmacological assessments with the monophasic action potential (MAP) recordings and blood sample analyses were performed before and 4 weeks after the start of drug administration.

KEY RESULTS

Amlodipine and cilnidipine decreased the blood pressure, while candesartan hardly affected it. The QT interval, MAP duration and beat-to-beat variability of the ventricular repolarization period were shortened only in the cilnidipine group, but such effects were not observed in the amlodipine or candesartan group. Plasma concentrations of adrenaline, angiotensin II and aldosterone decreased in the cilnidipine group. In contrast, plasma concentrations of angiotensin II and aldosterone were elevated in the amlodipine group, whereas in the candesartan group an increase in plasma levels of angiotensin II and a decrease in noradrenaline and adrenaline concentrations were observed.

CONCLUSIONS AND IMPLICATIONS

Long-term blockade of L/N-type Ca(2+) channels ameliorated the ventricular electrical remodelling in the hypertrophied heart which causes the prolongation of the QT interval. This could provide a novel therapeutic strategy for the treatment of cardiovascular diseases.

Search for a light pseudoscalar particle in the decay K_{L};{0}-->pi;{0}pi;{0}X

We performed a search for a light pseudoscalar particle X in the decay K_{L};{0}-->pi;{0}pi;{0}X, X-->gammagamma with the E391a detector at KEK. Such a particle with a mass of 214.3 MeV/c;{2} was suggested by the HyperCP experiment. We found no evidence for X and set an upper limit on the product branching ratio for K_{L};{0}-->pi;{0}pi;{0}X, X-->gammagamma of 2.4x10;{-7} at the 90% confidence level. Upper limits on the branching ratios in the mass region of X from 194.3 to 219.3 MeV/c;{2} are also presented.

Search for the Decay K L0-->pi0nu nu[over]

We performed a search for the K L0-->pi0nu nu[over] decay at the KEK 12-GeV proton synchrotron. No candidate events were observed. An upper limit on the branching ratio for the decay was set to be 6.7 x 10(-8) at the 90% confidence level.

Lymphangiosarcoma in a cat

This report describes a 5-year-old female cat with lymphangiosarcoma arising within the dermis and subcutis of the caudal mammary region. The mass presented as a large, poorly demarcated and fluctuant swelling with bruising of the overlying skin. Histopathologically, the dermis and subcutis in the affected region were diffusely oedematous, haemorrhagic, and infiltrated by plump spindle cells that formed irregular vascular clefts and cavernous channels. Neoplastic cells were aligned in one or more layers along oedematous collagenous trabeculae. The vascular clefts and channels contained only a few or no erythrocytes. The neoplastic cells had moderate to marked nuclear pleomorphism and prominent nucleoli. Lymphocytes and plasma cells were scattered throughout the neoplasm and the adjacent soft tissues. Immunohistochemical labelling revealed the neoplastic cells to express vimentin, factor VIII-related antigen and the lymphatic endothelial cell marker PROX-1, but the cells did not express cytokeratin. The nuclei of many neoplastic cells expressed the proliferation marker Ki67. These histopathological and immunohistochemical findings confirmed the diagnosis of lymphangiosarcoma. This is the first report describing the usefulness of expression of PROX-1 for differentiating between angiosarcoma of lymphatic and vascular origin in cats.

Renal dysplasia unrelated to claudin-16 deficiency in Japanese Black cattle

Renal lesions of the type usually found in claudin-16 (CL-16) defective Japanese Black cattle (homozygous for CL-16 deficiency) were identified in six animals of this breed, aged 28-59 months, which were either heterozygous for CL-16 deficiency (type 1) or normal, as judged by a DNA-based test associated with the CL-16 gene. Histopathologically, all six cases showed elongated focal lesions which ran through the cortex to terminate in the outer zone of the medulla. The lesions contained components that included: (1) immature tubules, (2) small irregularly shaped tubules with thickening of the basement membrane, (3) mesenchymal cells in an increased interstitium, (4) small atrophic glomeruli, and (5) immature glomeruli. The glomeruli were noticeably reduced in number, and large glomeruli with an increased number of mesangial cells were observed throughout the entire cortical area. Cystic dilation of tubules and flattening of the epithelium were noted in all areas of the kidney. Histopathologically, the renal lesions in the six cases were indistinguishable from those reported previously in cattle homozygous for CL-16 deficiency. These findings demonstrate that such renal lesions in Japanese Black cattle are not necessarily associated with homozygous deletion of the CL-16 gene.

Ultra-broadband optical parametric chirped-pulse amplification using an Yb: LiYF(4) chirped-pulse amplification pump laser

We demonstrate ultra-broadband optical parametric chirpedpulse amplification of 300-nm bandwidth pumped by a broadband pulse delivered from a diode-pumped, cryogenically-cooled Yb:YLF chirped- pulse amplification laser.

Deregulated expression of a novel component of TFTC/STAGA histone acetyltransferase complexes, rat SGF29, in hepatocellular carcinoma: possible implication for the oncogenic potential of c-Myc

c-Myc N-terminal conserved domains, MbI and MbII, are essential for c-Myc-mediated transformation and transactivation. These domains recruit the STAGA (SPT3-TAF9-GCN5-acetyltransferase) coactivator complex, but not TFTC (TATA-binding protein-free TAF-containing) to the target gene promoter. Although components of this complex are well conserved between yeast and mammals, four mammalian orthologs of yeast SPT8, SPT20, SGF11 and SGF29 remain to be identified. Here, we isolated a rat ortholog of yeast SGF29, a component of yeast SAGA (SPT-ADA-GCN5-acetyltransferase) complex. Both rat (r) SGF29 and c-myc mRNAs were overexpressed in five out of the eight tested rodent tumor cells. rSGF29 directly interacted with rADA3 and co-immunoprecipitated with two other TFTC/STAGA components, rGCN5 and rSPT3. rSGF29 was recruited to the c-Myc target gene promoters together with c-Myc, and it activated c-Myc target gene expressions. Downregulation of rSGF29 suppressed the expression of c-Myc target genes and inhibited anchorage-independent growth and tumorigenicity and lung metastasis of rat hepatoma K2 cells when injected into nude mice. These results show that rSGF29 is a novel component of TFTC/STAGA complexes and could be involved in the c-Myc-mediated malignant transformation.

Toll-like receptor 4-dependent recognition of structurally different forms of chemically synthesized lipid As of Porphyromonas gingivalis

Porphyromonas gingivalis is a Gram-negative anaerobic oral black-pigmented bacterium closely associated with chronic periodontitis. Lipopolysaccharide (LPS) derived from P. gingivalis is shown to be unusual because the LPS contains a greater number of lipid A species, such as tri-, tetra-, and/or penta-acylated lipid As. In this study, a lipid A possessing penta-fatty acyl chains derived from P. gingivalis strain 381 (compound PG-381-5FA) was synthesized, and examined for its immunobiological activities, compared with a tri-acylated lipid A (compound PG-381-3FA) synthesized previously. Compound PG-381-5FA, similar to compound PG-381-3FA, demonstrated weaker activity in a Limulus test as compared with Escherichia coli-type synthetic lipid A (compound 506). Compound PG-381-5FA, followed by compound PG-381-3FA, induced KC, interleukin-6, and tumour necrosis factor-alpha production in peritoneal macrophages from LPS-responsive C3H/HeN mice, but not in those from LPS-hyporesponsive C3H/HeJ mice. Furthermore, compound PG-381-5FA, as well as compound PG-381-3FA, activated nuclear factor-kappaB via Toll-like receptor (TLR)4/mD-2, but not TLR2, in a manner similar to compound 506, and worked as an antagonist for compound 506-induced cell activation. In the case of human peripheral blood mononuclear cells, compound PG-381-5FA showed much stronger IL-6-inducing activity than compound PG-381-3FA. The present results demonstrate that the chemical synthesis of a penta-acylated lipid A, mimicking the natural lipid A portion of LPS from P. gingivalis, is attributable to immune cell activation through TLR4, similar to that of compound 506.

Cardiac Vascular Hamartoma in Two Slaughtered Cattle

Two cases of cardiac vascular hamartoma were detected in slaughtered cattle. In each case, a single nodular protrusion (ca 2.5 cm in diameter) was located in the same part of the right atrium. Tortuous vessels of variable size with irregular lumina were seen on the cut surface of each nodule. Microscopically, there were many dysplastic vascular structures within the nodules. The vascular structures showed various changes such as irregular thickening of the tunica intima and the tunica media, walls with variable amounts of fibres (elastic, collagen and smooth muscle), some of which were disarranged. Mature adipose tissue and fibrous connective tissue were seen close to the vascular structures and intervascular tissue. In the nodules, bundles of cardiac muscle were disorganized, intermingled with connective tissue, and in some areas embedded within fibrous connective tissue.

Correlation between chemical structure and biological activities of Porphyromonas gingivalis synthetic lipopeptide derivatives

We recently separated a PG1828-encoded triacylated lipoprotein (Pg-LP), composed of two palmitoyl and one pentadecanoyl groups at the N-terminal of glycerocysteine from Porphyromonas gingivalis, a periodontopathic bacteria, and found that Pg-LP exhibited definite biological activities through Toll-like receptor (TLR) 2. In the present study, we synthesized 12 different Pg-LP N-terminal peptide moieties (PGTP) using four combinations of glyceryl (R and S) and cysteinyl (l and d) stereoisomers, and three different acyl group regioisomers, N-pentadecanoyl derivative (PGTP1), S-glycero 2-pentadecanoyl derivative (PGTP2) and S-glycero 3-pentadecanoyl derivative (PGTP3). All the PGTP compounds (RL, SL, SD, RD) tested showed TLR2-dependent cell activation. The activating capacities of the PGTP-R compounds were more potent than those of the PGTP-S compounds, whereas there were no differences between the PGTP-L and -D compounds. Furthermore, the production of interleukin (IL)-6 following stimulation with the PGTP1-RL, PGTP2-RL and PGTP3-RL compounds was impaired in peritoneal macrophages from TLR2 knock-out (KO), but not those from TLR1 KO or TLR6 KO mice. These results suggest that P. gingivalis triacylated lipopeptides are capable of activating host cells in a TLR2-dependent and TLR1-/TLR6-independent manner, and the fatty acid residue at the glycerol position in the PGTP molecule plays an important role in recognition by TLR2.

No proarrhythmic properties of the antibiotics Moxifloxacin or Azithromycin in anaesthetized dogs with chronic-AV block

BACKGROUND & PURPOSE

The therapeutically available quinolone antibiotic moxifloxacin has been used as a positive control for prolonging the QT interval in both clinical and non-clinical studies designed to assess the potential of new drugs to delay cardiac repolarization. Despite moxifloxacin prolonging QT, it has not been shown to cause torsades de pointes arrhythmias (TdP). Azithromycin is a macrolide antibiotic that has rarely been associated, clinically, with cases of proarrhythmia. As there is a lack of clinical data available, the cardiac safety of these drugs was assessed in a TdP-susceptible animal model by evaluating their repolarization and proarrhythmia effects.

EXPERIMENTAL APPROACH & KEY RESULTS

In transfected HEK cells, the IC(50)s for I (hERG) were 45+/-6 and 856+/-259 microg ml(-1) for moxifloxacin and azithromycin, respectively. Intravenous administration of 2 and 8 mg kg(-1) moxifloxacin (total peak-plasma concentrations 4.6+/-1.5 and 22.9+/-6.8 microg ml(-1)) prolonged the QT(c) in 6 anaesthetized dogs with chronic AV block by 7+/-3 and 21+/-19%, respectively. Similar intravenous doses of azithromycin (total peak-plasma concentrations 5.4+/-1.3 and 20.8+/-4.9 microg ml(-1)) had no electrophysiological effects in the same dogs. The reference compound, dofetilide (25 microg kg(-1) i.v.) caused QT(c) prolongation (29+/-15%) and TdP in all dogs. Beat-to-beat variability of repolarization (BVR), quantified as short-term variability of the left ventricular monophasic action potential duration, was only increased after dofetilide (1.8+/-0.7 to 3.8+/-1.5 ms; P<0.05).

CONCLUSION & IMPLICATIONS

As neither moxifloxacin nor azithromycin caused TdP or an increase in the BVR, we conclude that both drugs can be used safely in clinical situations.

Observation of a near-threshold D(0)D[over](0)pi(0) enhancement in B-->D(0)D[over](0)pi(0)Kappa decay

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.

Roles of virD4 and cagG genes in the cag pathogenicity island of Helicobacter pylori using a Mongolian gerbil model

BACKGROUND AND AIMS

The roles of the virD4 and the cagG genes in the cag pathogenicity island of Helicobacter pylori for gastroduodenal pathogenesis are unclear and their roles in vivo have not been examined.

METHODS

Seven week old male Mongolian gerbils were inoculated with the wild type H pylori TN2GF4, its isogenic virD4, or cagG mutants. Animals were sacrificed at 4, 12, and 24 weeks after inoculation. Gastric inflammation and H pylori density were evaluated by histology, inflammatory response (as measured by interleukin (IL)-1beta mRNA levels), proliferative activity (as assessed by 5'-bromo-2'deoxyuridine labelling indices), and host systemic reaction (as measured by anti-H pylori IgG antibody).

RESULTS

Degree of gastric inflammation, proliferative activity, and mucosal IL-1beta mRNA levels remained low throughout the first 12 weeks in gerbils infected with the virD4 mutants. Degree of gastric inflammation and proliferative activity increased at 24 weeks with the virD4 mutants reaching levels comparative with those seen at four weeks with the wild-type strains. Mucosal IL-1beta mRNA levels were also increased at 24 weeks with the virD4 mutants and levels at 24 weeks were similar between the wild-type and virD4 mutants. In contrast, gerbils infected with the cagG mutants had reduced ability to colonise gerbils, and no or little gastric inflammation or proliferative activity was observed.

CONCLUSIONS

Loss of the virD4 gene temporally retarded but did not abrogate gastric inflammation. Loss of the cagG gene abolished gastric inflammation partially via reduced ability to colonise gerbils. Unknown factors related to the type IV secretion system other than CagA may influence gastric inflammation.

Direct measurements of Ab and Ac using vertex and kaon charge tags at the SLAC detector

Exploiting the manipulation of the SLAC Linear Collider electron-beam polarization, we present precise direct measurements of the parity-violation parameters A(c) and A(b) in the Z-boson-c-quark and Z-boson-b-quark coupling. Quark-antiquark discrimination is accomplished via a unique algorithm that takes advantage of the precise SLAC Large Detector charge coupled device vertex detector, employing the net charge of displaced vertices as well as the charge of kaons that emanate from those vertices. From the 1996-1998 sample of 400 000 Z decays, produced with an average beam polarization of 73.4%, we find A(c)=0.673+/-0.029(stat)+/-0.023(syst) and A(b)=0.919+/-0.018(stat)+/-0.017(syst).

Physical and functional interaction between BH3-only protein Hrk and mitochondrial pore-forming protein p32

Bcl-2 homology domain (BH) 3-only proteins of the proapoptotic Bcl-2 subfamily play a key role as initiators of mitochondria-dependent apoptosis. To date, at least 10 mammalian BH3-only proteins have been identified, and it is now being realized that they have different roles and mechanisms of regulation in the transduction of apoptotic signals to mitochondria. Hrk/DP5 is one of the mammalian BH3-only proteins implicated in a variety of physiological and pathological apoptosis, yet the molecular mechanism involved in Hrk-mediated apoptosis remains poorly understood. In an attempt to identify cellular proteins participating in Hrk-mediated apoptosis, we have conducted yeast two-hybrid screening for Hrk-interacting proteins and isolated p32, a mitochondrial protein that has been shown to form a channel consisting of its homotrimer. In vitro binding, co-immunoprecipitation, as well as immunocytochemical analyses verified specific interaction and colocalization of Hrk and p32, both of which depended on the presence of the highly conserved C-terminal region of p32. Importantly, Hrk-induced apoptosis was suppressed by the expression of p32 mutants lacking the N-terminal mitochondrial signal sequence (p32(74-282)) and the conserved C-terminal region (p32 (1-221)), which are expected to inhibit binding of Hrk competitively to the endogenous p32 protein and to disrupt the channel function of p32, respectively. Furthermore, small interfering RNA-mediated knockdown of p32 conferred protection against Hrk-induced apoptosis. Altogether, these results suggest that p32 may be a key molecule that links Hrk to mitochondria and is critically involved in the regulation of Hrk-mediated apoptosis.

Evidence for direct CP violation in B0-->K+pi- decays

We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05<A(CP)(K+pi(0))<0.13 and -0.18<A(CP)(pi(+)pi(0))<0.14 at 90% confidence level.

Observation of B+-->psi(3770)K+

We report the first observation of the decay B+-->psi(3770)K+ where the psi(3770) is reconstructed in the D0(-)D(0) and D+D- decay channels. The obtained branching fraction is B(B+-->psi(3770)K+)=(0.48+/-0.11+/-0.07)x10(-3). We have measured the branching fraction for the decay B+-->D0(-)D0K+ to be (1.17+/-0.21+/-0.15)x10(-3) and set a 90% confidence level upper limit of 0.90 x 10(-3) for the decay B+-->D+D-K+. We also present the results of a search for possible decays to D(-)D and D0(-)D(0)pi(0) of the recently observed X(3872) particle. The analysis is based on 88 fb(-1) of data collected at the Upsilon(4S) resonance by the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.

Measurement of the CP asymmetry in B-->Xs gamma

Direct CP violation in the b-->sgamma process is a sensitive probe of physics beyond the standard model. We report a measurement of the CP asymmetry in B-->X(s)gamma, where the hadronic recoil system X(s) is reconstructed using a pseudoreconstruction technique. In this approach there is negligible contamination from b-->dgamma decays, which are expected to have a much larger CP asymmetry. We find A(CP)=0.002+/-0.050(stat)+/-0.030(syst) for B-->X(s)gamma events having recoil mass smaller than 2.1 GeV/c(2). The analysis is based on a data sample of 140 fb(-1) recorded at the upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring.

Thoracoscopic enucleation of esophageal stromal tumor

Gastrointestinal stromal tumor is a rare entity, especially in the esophagus. We report a patient with a stromal tumor of the esophagus who underwent a thoracoscopic enucleation of the tumor. The patient was a 61-year-old man complaining of slight dysphagia. A submucosal tumor of the middle thoracic esophagus was found endoscopically. The tumor was approximately 4.0 cm in diameter measured by endoscopic ultrasonography. On 17 May 2001, thoracoscopic enucleation of the esophageal tumor was performed using a Kodama Di-suction. The Kodama Di-suction was useful for the thoracoscopic enucleation of the submucosal tumor of the esophagus, acting as both a dissector and a sucker. The patient's course was uneventful after surgery. Histopathologically the esophageal tumor revealed a high cellularity, consisting of spindle cells, and the tumor cells were immunohistochemically positive for CD34 and c-kit protein, but not for a-smooth muscle actin or S-100 protein. From these findings, the esophageal submucosal tumor was diagnosed as gastrointestinal stromal tumor, distinguished from leiomyoma.

Observation of B(+)-->pppi+, B0-->ppK0, and B(+)-->ppK(*+)

We report the first observation of a b-->u type charmless baryonic B decay, B+-->pppi(+), as well as b-->s type B0-->ppK0 and B+-->ppK(*+) decays. The analysis is based on a 78 fb(-1) data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find B(B+-->pppi(+))=(3.06(+0.73)(-0.62)+/-0.37)x10(-6), B(B0-->ppK0)=(1.88(+0.77)(-0.60)+/-0.23)x10(-6), and B(B+-->ppK(*+))=(10.3(+3.6+1.3)(-2.8-1.7))x10(-6). We also update B(B+-->ppK+)=(5.66(+0.67)(-0.57)+/-0.62)x10(-6) and present an upper limit on B(B0-->ppK(*0)) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.

Measurement of /V(ub)/ using inclusive B-->X(u)lnu decays with a novel X(u)-reconstruction method

We report the measurement of an inclusive partial branching fraction for charmless semileptonic B decay and the extraction of /V(ub)/. Candidates for B-->X(u)lnu are identified with a novel X(u) reconstruction method based on neutrino reconstruction via missing 4-momentum and a technique called "simulated annealing." Based on 86.9 fb(-1) of data taken with the Belle detector, we obtain DeltaB(B-->X(u)lnu;M(X)<1.7 GeV/c2,q2>8.0 GeV2/c2)=[7.37+/-0.89(stat)+/-1.12(syst)+/-0.55(b-->c)+/-0.24(b-->u)]x10(-4) and determine |V(ub)|=[4.66+/-0.28(stat)+/-0.35(syst)+/-0.17(b-->c)+/-0.08(b-->u)+/-0.58(theory)]x10(-3).

Measurement of time-dependent CP-violating asymmetries in B0-->phiK(0)S, K+K-K0(S), and eta'K0(S) decays

We present an improved measurement of CP-violation parameters in B0-->phiK(0)(S), K(+)K(-)K(0)(S), and eta(')K(0)(S) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We find that the observed CP asymmetry in the B-->phiK(0)(S) decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.

Observation of B-->K*l+l-

We report the observation of the flavor-changing neutral current decay B-->K(*)l(+)l(-) and an im-proved measurement of the decay B-->Kl(+)l(-), where l represents an electron or a muon, with a data sample of 140 fb(-1) accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. The results for the branching fractions are B(B-->K(*)l(+)l(-))=(11.5(+2.6)(-2.4)+/-0.8+/-0.2)x10(-7) and B(B-->Kl(+)l(-))=(4.8(+1.0)(-0.9)+/-0.3+/-0.1)x10(-7), where the first error is statistical, the second is systematic and the third is from model dependence.

Observation of a narrow charmoniumlike state in exclusive B+/--->K+/-pi+pi-J/psi decays

We report the observation of a narrow charmoniumlike state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi. This state, which decays into pi(+)pi(-)J/psi, has a mass of 3872.0+/-0.6(stat)+/-0.5(syst) MeV, a value that is very near the M(D0)+M(D(*0)) mass threshold. The results are based on an analysis of 152M B-Bmacr; events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The signal has a statistical significance that is in excess of 10sigma.