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75 result(s) for "Takikawa Y."
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Pseudomonas syringae pv. actinidiae strains isolated from past and current epidemics to Actinidia spp. reveal a diverse population structure of the pathogen
A total of 40 Pseudomonas syringae pv. actinidiae (Psa) strains isolated from past and current epidemics of kiwifruit bacterial canker worldwide were compared using repetitive-sequence PCR (rep-PCR) fingerprinting with BOX, ERIC and REP primer sets. The strains were also assessed for the presence of 23 type III secretion system effector genes, tolerance to sodium arsenite, the presence of coronatine and phaseolotoxin and for growth trends in Actinidia deliciosa leaves. Rep-PCR revealed the occurrence of 11 different Psa lineages among the strains and indicated a relevant genetic variability within the strains isolated in Japan during 1984–2011, whereas all strains obtained from the current pandemic showed the same banding pattern. All lineages showed the same growth trend when inoculated into A. deliciosa leaves. The difference between Psa strains from past and current epidemics was confirmed by the detection of different repertoires of type III effector protein genes. Not all Psa strains isolated in Japan during past epidemics of kiwifruit bacterial canker amplify genes of the argK-tox cluster of phaseolotoxin, suggesting their absence or gene mutation. The results of an arsenic tolerance assay indicated that almost all strains isolated in Italy during the current epidemic of kiwifruit bacterial canker were relatively tolerant to 0.15–0.35 mM sodium arsenite, whereas those isolated in Chile and New Zealand were very sensitive. Remarkably, the two strains from China were tolerant or very sensitive. Collectively, these data indicate a composite population structure of this pathogen, which was able to diversify in Japan during 27 years of recurrent infections to A. deliciosa. The current naming of Psa populations based on their numbering and presence/absence of phytotoxins should be reconsidered.
Quantitative analysis of the lifelong production of conidia released from single colonies of Podosphaera xanthii on melon leaves using electrostatic techniques
Using an electrostatic rotational spore collector, we consecutively collected all of the conidia produced from single colonies of melon powdery mildew (Podosphaera xanthii Pollacci KMP-6 N) on leaves of living melon plants throughout the lifetime of the colony in a natural environment, and counted all conidia that were attracted to insulators. The collector consisted of an insulated round plastic container, a conductor (copper) film, an insulator (collector) film, an electrostatic voltage generator and a timer mechanism. Negative charge was supplied from the voltage generator to the conductor film, and the negatively charged conductor film caused dielectric polarization of the insulator film. The insulator film, which creates an attractive force for trapping conidia that enter the field, was placed ca. 2 cm from the apex of the single colony. Released conidia were successfully attracted to the electrostatically activated insulator films. Each collector film was exchanged for a new insulator film at 24 h intervals until KMP-6 N ceased to release conidia from single colonies. During a colony’s lifespan, KMP-6 N released an average of 12.6 × 104 conidia from each of the single colonies at ca. 744 h. Additionally, we found that 1) the number of conidia released from single colonies in daytime was larger than that in night-time, 2) conidia were released from single colonies for ca. 2–4 h longer in spring or summer than in autumn or winter, and 3) release of conidia from KMP-6 N decreased as light intensity declined. Thus, conidial release from conidiophores is affected by day-length and light intensity.
LIST OF NEW NAMES OF PLANT PATHOGENIC BACTERIA (2008-2010)
In 2010 the International Society of Plant Pathology Committee on the Taxonomy of Plant Pathogenic Bacteria published the Comprehensive List of Names of Plant Pathogenic Bacteria, 1980-2007 to provide an authoritative register of names of plant pathogens. In this manuscript we update the list of names by cataloguing names published from 2008 to 2010. We provide those names that have been validly and effectively published in this time frame, the proposed names that we judged to be invalid and names published earlier that did not make the previous lists. We also discuss problems that arise in the naming of strains that fall into the status Candidatus and nomenclatural problems in the genus Xanthomonas.
Fundamental study of subharmonic vibration of order 1 2 in automatic transmissions for cars
A torque converter is an element that transfers torque from the engine to the gear train in the automatic transmission of an automobile. The damper spring of the lock-up clutch in the torque converter is used to effectively absorb the torsional vibration caused by engine combustion. A damper with low stiffness reduces fluctuations in rotational speed but is difficult to use because of space limitations. In order to address this problem, the damper is designed using a piecewise-linear spring with three stiffness stages. However, the damper causes a nonlinear vibration referred to as a subharmonic vibration of order 1 2. In the subharmonic vibration, the frequency is half that of the vibrations from the engine. In order to clarify the mechanism of the subharmonic vibration, in the present study, experiments are conducted using the fundamental experimental apparatus of a single-degree-of-freedom system with two stiffness stages. In the experiments, countermeasures to reduce the subharmonic vibration by varying the conditions of the experiments are also performed. The results of the experiments are evaluated through numerical analysis using the shooting method. The experimental and analytical results were found to be in close agreement.
Optimal Design of Spring Characteristics of Damper for Subharmonic Vibration in Automatic Transmission Powertrain
In the torque converter, the damper of the lock-up clutch is used to effectively absorb the torsional vibration. The damper is designed using a piecewise-linear spring with three stiffness stages. However, a nonlinear vibration, referred to as a subharmonic vibration of order 1 2, occurred around the switching point in the piecewise-linear restoring torque characteristics because of the nonlinearity. In the present study, we analyze vibration reduction for subharmonic vibration. The model used herein includes the torque converter, the gear train, and the differential gear. The damper is modeled by a nonlinear rotational spring of the piecewise-linear spring. We focus on the optimum design of the spring characteristics of the damper in order to suppress the subharmonic vibration. A piecewise-linear spring with five stiffness stages is proposed, and the effect of the distance between switching points on the subharmonic vibration is investigated. The results of our analysis indicate that the subharmonic vibration can be suppressed by designing a damper with five stiffness stages to have a small spring constant ratio between the neighboring springs. The distances between switching points must be designed to be large enough that the amplitude of the main frequency component of the systems does not reach the neighboring switching point.
Effect of Stiffness Ratio of Piecewise-Linear Spring on the Occurrence of Subharmonic Nonlinear Vibration in Automatic Transmission Powertrain
In the torque converter, a damper with a piecewise-linear spring is used to reduce the forced vibration, and the subharmonic vibration occurs when the spring restoring torque characteristics approach the switching point. This research analyzed the effect of stiffness ratio between the neighboring piecewise-linear springs on the occurrence of the subharmonic nonlinear vibration in automatic transmission powertrain. The powertrain is modeled with multi degree-of-freedom nonlinear system as an actual vehicle. The result shows higher value of the stiffness ratio between the neighboring springs creates larger value of the subharmonic vibration.
Efficacy and safety of sofosbuvir–velpatasvir with or without ribavirin in HCV-infected Japanese patients with decompensated cirrhosis: an open-label phase 3 trial
BackgroundIn Japan, hepatitis C virus (HCV)-infected patients with decompensated cirrhosis currently have no treatment options. In this Phase 3 study, we evaluated sofosbuvir–velpatasvir with or without ribavirin for 12 weeks in patients with any HCV genotype and decompensated cirrhosis [Child–Pugh–Turcotte (CPT) class B or C] in Japan.MethodsPatients were randomized 1:1 to receive sofosbuvir–velpatasvir with or without ribavirin for 12 weeks. Randomization was stratified by CPT class and genotype. Sustained virologic response 12 weeks following completion of treatment (SVR12) was the primary efficacy endpoint.ResultsOf the 102 patients enrolled, 57% were treatment naive, 78% and 20% had genotype 1 and 2 HCV infection, respectively, and 77% and 20% had CPT class B and C cirrhosis, respectively, at baseline. Overall, 61% of patients were female and the mean age was 66 years (range 41–83). SVR12 rates were 92% (47/51) in each group. Among patients who achieved SVR12, 26% had improved CPT class from baseline to posttreatment week 12. Most adverse events (AEs) were consistent with clinical sequelae of advanced liver disease or known toxicities of ribavirin. Four patients (8%) who received sofosbuvir–velpatasvir and seven (14%) who received sofosbuvir–velpatasvir plus ribavirin experienced a serious AE. The 3 deaths (bacterial sepsis, gastric varices hemorrhage, hepatocellular carcinoma) were attributed to liver disease progression.ConclusionSofosbuvir–velpatasvir for 12 weeks provides a highly effective and well-tolerated therapy for Japanese patients with HCV and decompensated cirrhosis. Ribavirin did not improve efficacy but increased toxicity.
Occurrence of white top of pea caused by a new strain of Pseudomonas syringae pv. pisi
A new bacterial disease has been observed on pea in Shizuoka prefecture, Japan, since 1981. The disease occurs in early autumn when pea plants grow vigorously. The disease is characterized by chlorosis and whitening of apical shoots, including leaflets, stipules, and young pods. Usually, these white top (WT) symptoms are associated with extensive water-soaked lesions on stems and on leaflets at the basal part of the diseased plants. Thirty-four bacterial isolates from WT plants were characterized and identified together with 16 strains of Pseudomonas syringae pv. pisi from common bacterial blight of pea. The bacteria were gram-negative rods, having one to six polar flagella. The results of LOPAT tests were + - - - +, showing that they belong to P. syringe. In stab inoculation on stems, the WT isolates produced WT symptoms with water-soaked spots 14 days after inoculation. The 16 P. syringae pv. pisi strains never induced WT symptoms and, on the contrary, caused the typical bacterial blight. WT isolates were not pathogenic on any other plants tested. Phenotypic properties differentiated WT isolates and P. syringae pv. pisi strains into two groups; one consists of WT isolates and P. syringae pv. pisi group A, the other is P. syringae pv. pisi group B. Two distinct fingerprint profiles were identified by repetitive sequence based-polymerase chain reaction. WT isolates and P. syringae pv. pisi group A belonged to the same fingerprint type in rep-PCR, whereas a distinct fingerprint was shown by strains of the P. syringae pv. pisi group B. We concluded that the WT isolates should be included in P. syringae pv. pisi as a distinct strain in symptom expression.
Effects of Zinc Acetate on Serum Zinc Concentrations in Chronic Liver Diseases: a Multicenter, Double-Blind, Randomized, Placebo-Controlled Trial and a Dose Adjustment Trial
The essential trace element zinc maintains liver functions. Liver diseases can alter overall zinc concentrations, and hypozincemia is associated with various hepatic pathologies. Modulating systemic zinc through dietary supplementation is potentially useful for liver diseases. We evaluated the usefulness of zinc (NPC-02; acetate formulation) supplementation. We conducted two NPC-02 studies on zinc-deficient patients (serum zinc < 70 μg/dL). Study 1: double-blind, randomized, placebo-controlled trial on 57 subjects with chronic liver diseases comparing serum zinc in patients given NPC-02 (NPC-02 group) versus placebo (Placebo group). Study 2: dose adjustment study on 43 subjects with/without liver diseases to determine proportions maintaining serum zinc target (≥ 80 μg/dL but < 200 μg/dL). In study 1, NPC-02 subjects had higher serum zinc concentrations at week 8 than Placebo subjects (83.2 ± 20.2 and 61.3 ± 12.0, respectively; P  < 0.0001), and more NPC-02 than Placebo subjects achieved the serum zinc target (15/27 vs. 1/26). In study 2, the NPC-02-induced serum zinc increase was dose-dependent in subjects both with and without liver diseases ( r  = 0.5143, P  = 0.0022 and r  = 0.5753, P  = 0.0005, respectively). Interestingly, there was a marginally positive correlation between serum zinc and albumin levels in subjects with but not in those without liver diseases ( r  = 0.4028, P  = 0.0631 and r  = 0.1360, P  = 0.5567, respectively). NPC-02 dose-dependently increases serum zinc in hypozincemic patients, regardless of liver disease. NPC-02 is a potentially effective therapy for liver cirrhosis, in which zinc deficiency is common. Clinical trial registry number: NCT02337569, NCT02321865.
Prevention of critical telomere shortening by oestradiol in human normal hepatic cultured cells and carbon tetrachloride induced rat liver fibrosis
Background and aim: Significant telomere shortening of hepatocytes is associated with replicative senescence and a non-dividing state in chronic liver disease, resulting in end stage liver failure and/or development of hepatocellular carcinoma. To prevent critical telomere shortening in hepatocytes, we have focused on oestrogen dependent transactivation of the human telomerase reverse transcriptase (hTERT) gene as a form of telomerase therapy in chronic liver disease. Methods: We examined expression of hTERT mRNA and its protein, and telomerase activity (TA) in three human normal hepatic cell lines (Hc-cells, h-Nheps, and WRL-68) before and after treatment with 17β-oestradiol. The effects of exogenous oestradiol administration were examined in a carbon tetrachloride (CCl4) induced model of liver fibrosis in rats. Results: Expression of hTERT mRNA and its protein was upregulated by oestradiol treatment. Telomere length decreased in Hc-cells and h-Nheps with accumulated passages whereas with long term oestradiol exposure it was greater than without oestradiol. The incidence of β-galactosidase positive cells, indicating a state of senescence, decreased significantly in oestradiol treated cells in comparison with non-treated cells (p<0.05). TA in both male and female rats with CCl4 induced liver fibrosis was significantly higher with oestradiol administration than without (p<0.05). Long term oestradiol administration markedly rescued the hepatic telomere from extensive shortening in both male and female rats. Conclusion: These results suggest that oestradiol acts as a positive modulator of the hTERT gene in the liver. Oestrogen dependent transactivation of the hTERT gene is a new strategy for slowing the progression of chronic liver disease.