[Epidemiological investigation of colonic diverticulosis detected by computed tomography colonography].

Among 586 patients who underwent computed tomography colonography (CTC) from May 2012 to September 2017, 333 were diagnosed with colonic diverticulosis. The incidence of colonic diverticulosis increases with age. Despite a high frequency of ascending colonic diverticulosis, multiple diverticulosis (>10 in a colonic segment) were the most frequent in the sigmoid colon. In previous studies, the frequency of detection of colonic diverticulosis by CTC was higher than that by colonoscopy and barium enema. In addition, using CTC, the detection rate of colonic diverticulosis has been recently increasing, suggesting that CTC is the most sensitive procedure for detecting colonic diverticulosis.

Characterization of the Escherichia coli O157:H7 outbreak strain whose Shiga toxin 2 gene is inactivated by IS1203v insertion.

A total of 12 enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains were isolated during a recent outbreak in a nursery school in Ehime Prefecture, Japan. These isolates were considered to be derived from a common strain when analyzed using an IS-printing method and pulsed-field gel electrophoresis. PCR analysis revealed that the isolates harbor stx1, stx2, eae, and hlyA. However, assessment of the production of the Stx proteins revealed that these isolates produced Stx1 but not Stx2. We determined their stx2 variants such as stx2c and found that the size of the PCR product was much larger than the expected size. Sequencing of the entire stx2 gene revealed that a 1310-bp fragment was inserted into the coding region of the Stx2A subunit and that the sequences of the insert were identical to those of IS1203v. According to the sequences around the insertion site, additional amino acid residues should be attached at the C-terminus of the A subunit, which may hamper the Stx2 complex formation. Finally, this study also suggested that such an insertion may lead to the misinterpretation of results when screening EHEC isolates for virulence genes by PCR.

Food preservative potential of gassericin A-containing concentrate prepared from a cheese whey culture supernatant from Lactobacillus gasseri LA39.

Gassericin A (GA) is a circular bacteriocin produced by Lactobacillus gasseri LA39. In this study, GA-containing concentrate was prepared using a cross-flow membrane filtration device (30 kDa cut-off) from the culture supernatant of Lb. gasseri LA39 cultivated in a cheese whey-based food-grade medium. The bacteriocin activity titer in the concentrate was 16 times as high as that of the culture supernatant and was completely maintained through each incubation at 4°C for 3 months, 37°C for 2 months, 60°C for 5 h, and 100°C for 30 min. The GA-containing concentrate was used with glycine powder to make custard creams, and then four representative strains of custard cream spoilage bacteria (Bacillus cereus, Lactococcus lactis subsp. lactis, Achromobacter denitrificans and Pseudomonas fluorescens) were individually inoculated at c. 10(3) colony forming units/g in the custard creams. Throughout 30 days of incubation at 30°C, all of the inoculated bacteria were completely inhibited by the combination of 5% (w/w) of the GA-containing concentrate and 0.5% (w/w) glycine. This is the first highly practical application of GA to foods as a biopreservative, and the concentration method and the bacteriocin concentrate would contribute to biopreservation of several foods.

Development of a re-positionable aortic stent-valve: a preliminary study in swine.

BACKGROUND: Placement of aortic stent-valves in the proper position is difficult due to the high velocity and oscillation of blood flow and anatomical characteristics. To address this problem, a re-positionable stent-valve was designed and examined in a preliminary animal experiment. METHODS: Protocols for this animal study were approved by the institutional Animal Care and Use Committee. An umbrella-shaped polyurethane valve was attached at the tip of newly devised re-positionable metallic stent. The prosthesis (re-positionable stent-valve) was implanted in 5 female pigs via the right carotid artery using a 10-F introducer (Group A). As a control, the stent-without-valve was implanted in 4 female pigs (Group B). Efficacy of the valve was assessed by aortography and aortic pressure measurement. Animals were sacrificed 1 hour after stent-valve implantation for macroscopic examination. RESULTS: The stent-valve was successfully implanted in all pigs. In Group A, aortography showed good function of the polyurethane valve. No significant change in diastolic pressure was noted during valve testing. In Group B, aortography and aortic pressure measurement showed massive aortic regurgitation following dysfunction of the native aortic leaflets. Post-mortem examination showed small amounts of thrombus inside the polyurethane umbrella in Group A. CONCLUSION: Placement of the re-positionable stent-valve seems feasible and effective. However, the problem of thrombus formation inside the umbrella valve should be solved in future studies.

Automatic measurement of the nonlinearity parameter B/A in liquid media.

Using a 19-MHz focused Gaussian beam generated by a LiNbO(3) plate with an inverted polarization layer coupled to an acoustic lens, a method to automatically measure the nonlinearity parameter B/A in liquid media is presented. A liquid sample is poured into a cylindrical cell set with a glass tube on the lens surface. The focusing source emits burst waves. A tungsten rod immersed in the sample so that the top surface is normal to the beam axis behaves as a perfect reflector. The position of the reflector to maximize the amplitude receiving the returned wave determines the sound speed c of the sample. The amplitude measurement for the waves returned from the lens-sample interface and the reflector surface leads to the determination of the density rho and attenuation coefficient alpha, respectively. Then the B/A is finally derived by summarizing the measured result of the 38-MHz second harmonic amplitude contained in the sound returned back from the reflector, together with rho, c and alpha. All these are automatically processed in a short time less than 2 min with the performance of computer controlled instruments.

An ultrasonic transducer for second harmonic imaging using a LiNbO3 plate with a local ferroelectric inversion layer.

A new lithium niobate (LiNbO3) transducer of separated transmitter-receiver configuration is proposed for application to second harmonic imaging in a high-frequency range. In this transducer, a domain-inverted layer of half the plate thickness is formed selectively by Ti-diffusion and heat treatment in the central part of a LiNbO3 plate. The uniformly polarized surrounding region is used as the transmitter that will generate the fundamental wave component. A transducer with the transmission frequency of 50 MHz and the reception frequency of 100 MHz is fabricated using a 36 degrees rotated Y-cut LiNbO3 plate, and its performance is demonstrated.

Analysis of thickness-extensional waves propagating in the lateral direction of solidly mounted piezoelectric thin film resonators.

In a solidly mounted piezoelectric thin film resonator (SMR), acoustic waves propagate not only in the thickness direction but also in the lateral direction. In this study, we analyzed the acoustic wave in the SMR-type piezoelectric thin film resonator and derived the dispersion relation between the lateral wave number and frequency, considering wave propagation in the lateral direction. The lateral wave number was shown to be a complex number due to the leak of the acoustic energy to a substrate. It also was shown that the Q factor could be calculated from the complex cutoff frequency, and it becomes higher when the number of quarter-wave (lambda/4) layers increases. Using the dispersion relation, the trapped-energy resonant modes of an SMR were analyzed, considering the boundary conditions at the edge of the electrode.

OKP cells express the Na-dicarboxylate cotransporter NaDC-1.

Urinary citrate concentration, a major factor in the formation of kidney stones, is primarily determined by its rate of reabsorption in the proximal tubule. Citrate reabsorption is mediated by the Na-dicarboxylate cotransporter-1 (NaDC-1). The opossum kidney (OKP) cell line possesses many characteristics of the renal proximal tubule. The OKP NaDC-1 (oNaDC-1) cDNA was cloned and encodes a 2.4-kb mRNA. When injected into Xenopus oocytes, the cotransporter is expressed and demonstrates Na-coupled citrate transport with a stoichiometry of >or=3 Na:1 citrate, specificity for di- and tricarboxylates, pH-dependent citrate transport, and pH-independent succinate transport, all characteristics of the other NaDC-1 orthologs. Chronic metabolic acidosis increases proximal tubule citrate reabsorption, leading to profound hypocitraturia and an increased risk for stone formation. Under the conditions studied, endogenous OKP NaDC-1 mRNA abundance is not regulated by changes in media pH. In OKP cells transfected with a green fluorescent protein-oNaDC-1 construct, however, media acidification increases Na-dependent citrate uptake, demonstrating posttranscriptional acid regulation of NaDC-1 activity.

Broadband ultrasonic transducers using a LiNbO3 plate with a ferroelectric inversion layer.

Some heat treatment of a lithium niobate (LiNbO3) plate induces domain inversion, thereby yielding a ferroelectric inversion layer. In such a piezoelectric plate with an inversion layer, even-order thickness-extensional modes, as well as odd-order modes, can be excited piezoelectrically. Therefore, the ultrasonic transducer using such a piezoelectric plate is expected to operate over a wide frequency range. In this paper, it is shown that broadband ultrasonic transducers can be obtained at a certain thickness ratio of inversion layer to plate, and that the transducer characteristics differ depending on whether the inversion layer is on the front side or on the backside. The broadband characteristics are experimentally demonstrated by fabricating transducers with 9 MHz or 75 MHz center frequency using 36 degrees rotated Y-cut LiNbO3 plates with a ferroelectric inversion layer.