Prevalence of Salmonella isolates and antimicrobial resistance patterns in chicken meat throughout Japan

We investigated the prevalence of Salmonella in chicken meat from northern, central, and southern Japan. Between 2006 and 2008, 821 samples from these three regions were collected and examined. Salmonella isolates were detected in 164 (20.0%) of these samples, with 15 (10.0%) of 150, 113 (27.5%) of 411, and 36 (13.8%) of 260 recovered from the northern, central, and southern regions, respectively. We recovered 452 Salmonella isolates. From the isolates, 27 serovars were identified; the predominant serovars isolated were Salmonella Infantis (n=81), Salmonella Kalamu (n=56), and Salmonella Schwarzengrund (n=43). Of the 452 isolates, 443 (98.0%) were resistant to one or more antibiotics, and 221 (48.9%) showed multiple-antibiotic resistance, thereby implying that multiple-antibiotic resistant Salmonella organisms are widespread in chicken meat in Japan. Resistance to oxytetracycline was most common (72.6%), followed by dihydrostreptomycin (69.2%) and bicozamycin (49.1%). This study, the first to report Salmonella prevalence in chicken meat throughout Japan, could provide valuable data for monitoring and controlling Salmonella infection in the future.     

Involvement of calcium in interactions between gingival epithelial cells and Porphyromonas gingivalis

Porphyromonas gingivalis, a periodontal pathogen can invade primary cultures of gingival epithelial cells. This invasion was significantly inhibited (74-81%) by thapsigargin and 1,2-bis(2-aminophenoxy)ethane-N,N,N1,N1-tetraacetic acid, acetoxymethyl ester (BAPTA/AM), but not by EDTA or amiloride. Release of Ca2+ from an intracellular store and the subsequent increase in cytosolic [Ca2+] may, therefore, be involved in the invasion process, while Ca2+ influx is not. Moreover, cytosolic [Ca2+] was found to increase transiently in about 30% of gingival epithelial cells acutely exposed to P. gingivalis, but not in unexposed cells, or in cells exposed to noninvasive Escherichia coli. These findings indicate that P. gingivalis invasion of epithelial cells is correlated with activation of [Ca2+]-dependent host cell signaling systems.     

Optical-waveguide microdisplacement sensor

As a novel application of integrated optics, a detection method of microdisplacement is proposed and its first demonstration is reported. The sensor has the Michelson interferometer configuration composed of an optical waveguide hybrid coupler. The operation was confirmed by building and testing the sensor using a Ti-diffused LiNbO3 waveguide.     

Low-drive-power asymmetric Mach-Zehnder modulator with band-limitedoperation

A novel 2×2 asymmetric Mach-Zehnder interferometric modulator is fabricated on Ti:LiNbO₃ waveguide and tested at microwave frequency. Band-limited operation was realized by using a traveling-wave periodic polarity reversed structure with the asymmetric strip line as the modulator electrode instead of the conventional coplanar waveguide. For a modulator with a three-section polarity reversed electrode, a 3-dB bandwidth of 7 GHz was obtained experimentally from 9 to 16 GHz centered at 12 GHz     

Physically based reflectance model utilizing polarization measurement

A surface bidirectional reflectance distribution function (BRDF) depends on both the optical properties of the material and the microstructure of the surface and appears as combination of these factors. We propose a method for modeling the BRDF based on a separate optical-property (refractive-index) estimation by polarization measurement. Because the BRDF and the refractive index for precisely the same place can be determined, errors cased by individual difference or spatial dependence can be eliminated. Our BRDF model treats the surface as an aggregation of microfacets, and the diffractive effect is negligible because of randomness. An example model of a painted aluminum plate is presented.     

Picosecond pulse response of broad-band guided-wave interferometric light modulators

Picosecond pulse operation of the guided-wave light modulator is reported in this paper. First, we analyze the time responses of phase and intensity modulators of the traveling-wave type, and the modulated output waveforms related to the modulating pulses are discussed. It is shown that there is an optimum interaction (or electrode) length of the modulator whereby the drive voltage is minimized for a desired output pulse width. The traveling-wave push-pull light intensity modulator of Ti-diffused LiNbO3waveguides was modulated by a pulse train of 1 GHz repetition frequency, and the modulated output was observed by the image tube streak camera modified for sinusoidal scan at the same frequency. The duration of the modulated light pulses was less than 45 ps, which shows good agreement with the predicted one.     

Morphology and breaking of latex particle deposits at a cylindrical collector in a microfluidic chamber

We report an analysis for the morphology and breaking behavior of deposits of spherical latex particles (1 and 3.6 μm in diameter) at a cylindrical collector in a microfluidic channel fabricated by soft-lithography. In-situ observation of particle deposition over a large range of flow rate conditions evidence the relationship between deposit morphology and mode of particle transport toward the collector. For low Pe?clet number (Pe), particle deposits are nearly uniform all over the collector surface except at the rear where particles do not attach. Upon increase of Pe, deposits gradually adopt a columnar morphology at the collector stagnation point. These results are qualitatively consistent with previously reported Monte Carlo simulations of deposits formation in stagnation point flow systems. However, these simulations fail to quantitatively predict the observed deposition at the rear of the collector for sufficiently high flow rate. Additional deposit breaking experiments together with numerical evaluations of particle flux around the collector suggest that such "anomalous" deposition at large Pe is significantly governed by concomitant detachment of deposited particles at the stagnation point and the presence of recirculation flow at the collector rear. Finally, kinetics of deposition are discussed in connection with particle size-dependence of deposit breaking features.     

Detection of norovirus RNA in bivalve molluscs by using bacteria-culture-employed method (A3T method)

Norovirus (NV) RNA has rarely been detected in foods despite the use of highly sensitive methods such as RT-PCR and real-time RT-PCR. In the modified method (A3T method) reported previously, a bacterial culture process was introduced into the standard protocol for NV detection to remove some inhibitor(s) present in food ingredients. To confirm the efficiency of the A3T method and to examine NV contamination in bivalve molluscs, we tried to detect NV RNA in bivalve molluscs on the market and in oyster samples associated with foodborne outbreaks by using the standard method and the A3T method. NV RNAs were detected in 20 samples (18.0%) of 111 bivalve molluscs, including oysters, on the market by use of the A3T method, while only one sample (0.9%) was positive according to the standard method. NV RNA was also detected in 10 of 35 oyster samples related to foodborne outbreaks by the A3T method. Those results show that the A3T method is suitable for the detection of NV in bivalve molluscs in general laboratories.     

Photoanodic response of iron oxide electrode in aqueous solution and its application to Pb removal under visible light irradiation

The iron oxide electrode was prepared from thermal oxidation of iron at 600 °C for 3 h in air atmosphere. This electrode with the structure of Fe₃O₄ and α-Fe₂O₃ showed the response of photoanodic current to the light with wavelength shorter than 600 nm. The band gap energy of this electrode was 1.99 eV. The onset potential of distinct steady photocurrent and also the flatband potential were 0.80 and 0.09 V vs. Ag/AgCl, respectively, in 0.1 M HNO₃ aqueous solution. The cell consisting of the iron oxide photoanode in HNO₃-Pb(NO₃)₂ and the graphite cathode in H₂SO₄-Ce(SO₄)₂ caused the PbO₂ deposit on the surface of the former electrode due to visible light irradiation without application of voltage. By holding the potential of this electrode at more positive value than 0.90 V, the photoanodic removal rate of Pb²⁺ in HNO₃-Pb(NO₃)₂ solution was higher than that observed when Ce⁴⁺ was used as electron acceptor.