Deformation and fracture of single-crystal and sintered polycrystalline silicon carbide produced by cavitation

An investigation was conducted to examine the deformation and fracture behavior of single-crystal and sintered polycrystalline SiC surfaces exposed to cavitation. Cavitation erosion experiments were conducted in distilled water at 25 C by using a magnetostrictive oscillator in close proximity (1 mm) to the surface of SiC. The horn frequency was 20 kHz, and the double amplitude of the vibrating disk was 50 microns. The results of the investigation indicate that the SiC (0001) surface could be deformed in a plastic manner during cavitation. Dislocation etch pits were formed when the surface was chemically etched. The number of defects, including dislocations in the SiC (0001) surface, increased with increasing exposure time to cavitation. The presence of intrinsic defects such as voids in the surficial layers of the sintered polycrystalline SiC determined the zones at which fractured grains and fracture pits (pores) were generated. Single-crystal SiC had superior erosion resistance to that of sintered polycrystalline SiC

Monochloramine inhibits ultraviolet B-induced p53 activation and DNA repair response in human fibroblasts

AbstractMonochloramine (NH2Cl) is one of the inflammation-derived oxidants, and has various effects on cell cycle, apoptosis and signal transduction. We studied the effects of NH2Cl on DNA repair response induced by ultraviolet B (UVB) irradiation in normal human diploid fibroblasts, TIG-1. TIG-1 irradiated with 20 mJ/cm2 UVB showed marked increase in thymine dimer, which decreased by about 50% after 24 h. This decrease in thymine dimer was significantly attenuated (P<0.05) by the pretreatment of NH2Cl (200 μM), which indicated DNA repair inhibition. UVB induced p53 phosphorylation at Ser15, Ser20 and Ser37, and p53 accumulation, and NH2Cl also inhibited these changes. Consequently, UVB-induced increase in the downstream effectors of p53, namely p21Cip1 and Gadd45a, were almost completely inhibited by NH2Cl. Immunoprecipitation study indicated that the association of p53 and MDM2, an E3 ubiquitin ligase for p53, did not change substantially by NH2Cl and/or UVB. The phosphorylation of p53 (Ser15 and Ser37) by UVB is catalyzed by ATR (ataxia telangiectasia mutated and Rad3 related kinase), which works as DNA damage sensor, and ATR also phosphorylates checkpoint kinase 1(Chk1) at Ser345. NH2Cl also inhibited the phosphorylation of Chk1 (Ser345). As UVB-induced DNA damage is repaired by nucleotide excision repair (NER) in human cells, these findings indicated that NH2Cl inhibited NER through the inhibition of p53 phosphorylation and accumulation, and NH2Cl probably impaired DNA damage recognition and/or ATR activation. NH2Cl may facilitate carcinogenesis through the inhibition of NER that repairs DNA damages from various carcinogens

Oxidative modification of IκB by monochloramine inhibits tumor necrosis factor α-induced NF-κB activation

AbstractWe have previously reported that monochloramine (NH2Cl), a neutrophil-derived oxidant, inhibited tumor necrosis factor α (TNFα)-induced expression of cell adhesion molecules and nuclear factor-κB (NF-κB) activation (Free Radical Research 36 (2002) 845–852). Here, we studied the mechanism how NH2Cl inhibited TNFα-induced NF-κB activation, and compared the effects with taurine chloramine (Tau–NHCl). Pretreatment of Jurkat cells with NH2Cl at 70 μM resulted in suppression of TNFα-induced IκB phosphorylation and degradation, and inhibited NF-κB activation. In addition, a slow-moving IκB band appeared on SDS-PAGE. By contrast, Tau–NHCl for up to 200 μM had no effects. Interestingly, NH2Cl did not inhibit IκB kinase activation by TNFα. Protein phosphatase activity did not show apparent change. When recombinant IκB was oxidized by NH2Cl in vitro and phosphorylated by TNFα-stimulated Jurkat cell lysate, its phosphorylation occurred less effectively than non-oxidized IκB. In addition, when NF-κB–IκB complex was immunoprecipitated from NH2Cl-treated cells and phosphorylated in vitro by recombinant active IκB kinase, native IκB but not oxidized IκB was phosphorylated. Amino acid analysis of the in vitro oxidized IκB showed methionine oxidation to methionine sulfoxide. Although Tau–NHCl alone had little effects on TNFα-induced NF-κB activation, simultaneous presence of Tau–NHCl and ammonium ion significantly inhibited the NF-κB activation, probably through the conversion of Tau–NHCl to NH2Cl. These results indicated that NH2Cl inhibited TNFα-induced NF-κB activation through the oxidation of IκB, and that NH2Cl is physiologically more relevant than Tau–NHCl in modifying NF-κB-mediated cellular responses

Evaluation of tumor markers for the detection of hepatocellular carcinoma in Yangon General Hospital, Myanmar.

Levels of alpha-fetoprotein (AFP), its glycoforms AFP-L3 and AFP-P4, and proteins induced by vitamin K absence or antagonist-II (PIVKA-II) were determined in sera obtained from patients in Yangon General Hospital (20 with hepatocellular carcinoma (HCC), 29 with chronic liver diseases, including 3 with chronic hepatitis and 26 with cirrhosis of the liver, and 9 with other hepatobiliary diseases). Forty-five percent of the patients with HCC had serum AFP levels above 10,000 ng/ml, indicating that nearly half of the HCC patients were at an advanced stage of the disease. Thus, the AFP sensitivity was as high as 70% with 100% specificity for a cutoff level of 200 ng/ml. The sensitivity of AFP-L3 was 75% and a specificity 90% for a cutoff level of 15%. AFP-P4 showed a higher sensitivity of 80% and a similar specificity of 86% for a cutoff level of 12%. Combined evaluation of AFP-L3 and/or AFP-P4 increased the sensitivity to 90% with the same specificity of 86%, indicating that AFP-L3 and AFP-P4 are useful as adjuncts for diagnosis of HCC in the present population. PIVKA-II had a high sensitivity of 90%, although the specificity was lower than 45%, probably due to the low cutoff level, as some cholestatic patients were included in the control group.</p

Number of Yellow Plaques Detected in a Coronary Artery Is Associated With Future Risk of Acute Coronary Syndrome Detection of Vulnerable Patients by Angioscopy

ObjectivesWe sought to test whether the risk of acute coronary syndrome (ACS) can be estimated by angioscopy.BackgroundDisruption of vulnerable plaque and subsequent thrombosis is regarded as a major mechanism of ACS. Although yellow plaques are supposedly vulnerable, the association between angioscopically determined extent of coronary atherosclerosis and risk of ACS events has not been reported.MethodsPatients (n = 552) who received catheterization and angioscopic examination for the diagnosis of coronary artery diseases were prospectively included and followed up for new onset of ACS events. Yellow color intensities of all detected yellow plaques were graded as 1, 2, or 3 according to the standard colors. Number of yellow plaques (NYP) in a coronary artery and maximum color grade of detected yellow plaques (maxYP) were determined. Association between the incidence of ACS events and angioscopic findings were analyzed.ResultsFollow-up interval was 57.3 ± 22.1 months. Acute coronary syndrome events were detected in 39 patients (7.1%). Although maxYP was not statistically different (2.0 ± 0.7 vs. 1.8 ± 0.9; p = 0.18), NYP was higher in the patients with an ACS event than those without the event (3.1 ± 1.8 vs. 2.2 ± 1.5; p = 0.008). Patients with NYP ≥2 and those with NYP ≥5 had 2.2- and 3.8-fold higher event rates, respectively, than those with NYP 0 or 1 (9.0% and 15.6%, respectively, vs. 4.1%; p = 0.02). Multivariate logistic regression analysis revealed NYP and multivessel disease as the independent risk factors of ACS events.ConclusionsPatients with multiple yellow plaques per vessel have a higher risk of suffering ACS events than those with NYP 0 or 1. Angioscopy would be useful to detect vulnerable patients

In-Stent Yellow Plaque at 1 Year After Implantation Is Associated With Future Event of Very Late Stent Failure The DESNOTE Study (Detect the Event of Very late Stent Failure From the Drug-Eluting Stent Not Well Covered by Neointima Determined by Angioscopy)

AbstractObjectivesThis study examined whether coronary angioscopy-verified in-stent yellow plaque at 1 year after drug-eluting stent (DES) implantation is associated with future event of very late stent failure (VLSF).BackgroundAtherosclerosis detected as yellow plaque by angioscopy has been associated with future events of acute coronary syndrome. Development of in-stent neoatherosclerosis is a probable mechanism of VLSF.MethodsThis study included 360 consecutive patients who received successful angioscopic examination at 1 year after implantation of a DES. They were clinically followed up for VLSF defined as cardiac death, acute myocardial infarction or unstable angina, or need for revascularization associated with the stent site.ResultsThe follow-up interval was 1,558 ± 890 days (4.3 ± 2.4 years). The incidence of VLSF was significantly higher in the patients with yellow plaque than in those without (8.1% vs. 1.6%; log rank p = 0.02). Multivariable analysis revealed the presence of yellow plaque (hazard ratio [HR]: 5.38; p = 0.02) and absence of statin therapy (HR: 3.25; p = 0.02) as risks of VLSF.ConclusionsIn-stent atherosclerosis evaluated by yellow plaque at 1 year after the implantation of DES and the absence of statin therapy were risks of VLSF. The underlying mechanism of VLSF appeared to be the progression of atherosclerosis as demonstrated by the yellow plaque

The Nature of Ultra-Luminous Compact X-Ray Sources in Nearby Spiral Galaxies

Studies were made of ASCA spectra of seven ultra-luminous compact X-ray sources (ULXs) in nearby spiral galaxies; M33 X-8 (Takano et al. 1994), M81 X-6 (Fabbiano 1988b; Kohmura et al. 1994; Uno 1997), IC 342 Source 1 (Okada et al. 1998), Dwingeloo 1 X-1 (Reynolds et al. 1997), NGC 1313 Source B (Fabbiano & Trinchieri 1987; Petre et al. 1994), and two sources in NGC 4565 (Mizuno et al. 1999). With the 0.5--10 keV luminosities in the range 10^{39-40} ergs/s, they are thought to represent a class of enigmatic X-ray sources often found in spiral galaxies. For some of them, the ASCA data are newly processed, or the published spectra are reanalyzed. For others, the published results are quoted. The ASCA spectra of all these seven sources have been described successfully with so called multi-color disk blackbody (MCD) emission arising from optically-thick standard accretion disks around black holes. Except the case of M33 X-8, the spectra do not exhibit hard tails. For the source luminosities not to exceed the Eddington limits, the black holes are inferred to have rather high masses, up to ~100 solar masses. However, the observed innermost disk temperatures of these objects, Tin = 1.1--1.8 keV, are too high to be compatible with the required high black-hole masses, as long as the standard accretion disks around Schwarzschild black holes are assumed. Similarly high disk temperatures are also observed from two Galactic transients with superluminal motions, GRO 1655-40 and GRS 1915+105. The issue of unusually high disk temperature may be explained by the black hole rotation, which makes the disk get closer to the black hole, and hence hotter.Comment: submitted to ApJ, December 199

Modification of single-nucleotide polymorphism in a fully humanized CYP3A mouse by genome editing technology

Abe, S., Kobayashi, K., Oji, A. et al. Modification of single-nucleotide polymorphism in a fully humanized CYP3A mouse by genome editing technology. Sci Rep 7, 15189 (2017). https://doi.org/10.1038/s41598-017-15033-

High prevalence of hepatitis C in patients with thalassemia and patients with liver diseases in Myanmar (Burma).

We conducted Myanmar-Japan cooperation studies on hepatitis B and hepatitis C virus markers in patients with thalassemias and those with liver diseases. Among the 102 patients with liver diseases, 92% had a history of hepatitis B virus infection (antibody to hepatitis B core antigen positive), 35% were hepatitis B surface antigen positive, 39% were positive for anti-HCV. Among 28 patients with hepatocellular carcinoma, 46% had hepatitis B surface antigen, 21.4% had antibody to hepatitis C virus, and 7% were positive for both hepatitis B surface antigen and anti hepatitis C virus. The history of HCV infection among blood recipients at the Haematology Department of the Yangon General Hospital and at the Yangon Children's Hospital was found to be 55.5% and 46.7%, respectively, which is comparable to the history of hepatitis B infection (66.7% and 46.7%, respectively). This preliminary survey also encountered 2 cases positive for anti-HCV among 34 voluntary blood donors. This survey is the first one to report that hepatitis C is at the epidemic stage in Myanmar. As there is no effective treatment for hepatitis C in this country, a screening program for blood used in transfusion should be started immediately.</p