Prevention of TNF-induced necrotic cell death by rottlerin through a Nox1 NADPH oxidase

Previous studies have demonstrated that rottlerin, a specific PKCdelta inhibitor, potentiates death receptor- mediated apoptosis through a cytochrome c-dependent or -independent pathway. However, its ability to regulate necrotic cell death, as well as the underlying mechanism, remains unknown. We found that in murine fibrosarcoma L929 cells, treatment with rottlerin protected the cells against TNF-induced necrosis, whereas it sensitized the cells to apoptosis induced by co-treatment with Hsp90 inhibitor geldanamycin and TNF, in a manner independent of its ability to inhibit PKC-delta. TNF treatment induced rapid accumulation of mitochondrial superoxide (O2-) through the Nox1 NADPH oxidase when cells undergo necrosis. Moreover, pretreatment with rottlerin failed to induce the GTP-bound form of small GTPase Rac1 by TNF treatment, and subsequently suppressed mitochondrial O2- production and poly(ADP-ribose) polymerase activation, thus inhibiting necrotic cell death. Therefore, our study suggests that Nox1 NADPH oxidase is a new molecular target for anti-necrotic activity of rottlerin upon death-receptor ligation.     

Effect of burn-up on the radioactivation behavior of cladding hull materials studied using the ORIGEN-S code

The effect of fuel burn-up on the radioactivation behavior of cladding hull materials was investigated using the ORIGEN-S code for various materials of Zircaloy-4, Zirlo, HANA-4, and HANA-6 and for various fuel burn-ups of 30, 45, 60, and 75 GWD/MTU. The Zircaloy-4 material is the only one that does not contain Nb as an alloy constituent, and it was revealed that ¹²⁵Sb, ^125mTe, and ⁵⁵Fe are the major sources of radioactivity. On the other hand, ^93mNb was identified as the most radioactive nuclide for the other materials although minor radioactive nuclides varied owing to their different initial constituents. The radioactivity of ⁹⁴Nb was of particular focus owing to its acceptance limit against a Korean intermediate-/low-level waste repository. The radioactivation calculation results revealed that only Zircaloy-4 is acceptable for the Korean repository, while the other materials required at least 4,900 of Nb decontamination factor owing to the high radioactivity of ⁹⁴Nb regardless of the fuel burn-up. A discussion was also made on the feasibility of Zr recovery methods (chlorination and electrorefining) for selective recovery of Zr so that it can be disposed of in the Korean repository.     

Simple,coupled algorithms for solving creeping flows and their application to electro‐osmotic flows

In this study we developed simple, coupled algorithms for solving low‐Reynolds‐number flows applicable to micro‐scale flows such as electro‐osmotic flows. The most popular scheme, i.e. the projection method, is not suitable for such flows because of its undesirable slip effect on boundaries at low‐Reynolds‐numbers. In our method, the velocity and pressure are strongly coupled, and the momentum and pressure equations are solved iteratively by using the successive over relaxation (SOR) method while exchanging the unknown variables as soon as they have been updated. The developed methods are applied to a model flow for evaluating their performance. It was found that the coupled schemes are indeed superior to a projection method, i.e. the fractional‐step method, in both numerical accuracy and CPU time. The code is then applied to a dc electro‐osmotic flow within a cavity driven by electrical force acting on the ions spread in the fluid. In this application, the system of equations for the fluid flow and that for the ion transport are solved in a decoupled way, but each system is solved by using fully implicit schemes. From the simulations and by introducing the concept of vorticity source, we can identify two roles of the body force, one contributing to build‐up of the osmotic pressure and the other to the fluid flow. The interesting reverse flow occurring after the external potentials applied on the electrodes have been shut off is also investigated in terms of the vorticity source. Copyright © 2010 John Wiley & Sons, Ltd.     

The Fer tyrosine kinase regulates interactions of Rho GDP-Dissociation Inhibitor α with the small GTPase Rac

Background  

RhoGDI proteins are important regulators of the small GTPase Rac, because they shuttle Rac from the cytoplasm to membranes and also protect Rac from activation, deactivation and degradation. How the binding and release of Rac from RhoGDI is regulated is not precisely understood.     

Radionuclides analysis in hot spring waters in Korea by liquid scintillation counting

Tritium and ¹⁴C concentration in hot spring water in Korea were determined. Tritium in the most hot spring samples could not detected and concentration range was <0.5?C1.31?TU. And ¹⁴C contents were ranged 1.7?C78.6?pMC. From the ³H and ¹⁴C analysis, we found some hot springs are mixed with recent groundwater and hot spring water ages were estimated from 1,940 to 32,800?years. And also, ²²⁶Ra and ²²⁸Ra were determined simultaneously in hot spring water, and some other radionuclides were also analyzed. Content distribution of ²²²Rn was 50?C3,760?pCi/L, ²²⁶Ra was <0.003?C0.15?Bq/L and ²²⁸Ra was below the detection limit.     

Deoxydesulfurization of dibenzothiophene sulfone over cesium/MCM-41 catalysts

Dibenzothiophene sulfone, one of the products of the oxidative desulfurization of heavy oil, can be utilized through catalytic cracking. The object of the present study is to provide Cs/MCM-41 catalysts for the removal of sulfur dioxide from dibenzothiophene sulfone. Cesium oxide was deposited via an impregnation method on MCM-41, and the catalytic performances of the samples were investigated during the deoxydesulfurization of dibenzothiophene sulfone to biphenyl and sulfur dioxide gas. The influence of cesium loading on the basic properties of MCM-41 was estimated by the temperature-programmed desorption of carbon dioxide. The dibenzothiophene sulfone conversions of the MCM-41, Cs(1 wt%)/MCM-41, Cs(3 wt%)/MCM-41 and Cs(10 wt%)/MCM-41 catalysts were 38.5, 52.1, 72.4 and 40.9%, respectively, which implies that the Cs(3 wt%)/MCM-41 catalyst has the highest activity. This result agrees with the finding of the basicity enhancement of MCM-41 with the addition of cesium, in which Cs(3 wt%)/MCM-41 exhibited a maximum number of basic sites.     

Study on the effects of gadolinium-based MRI contrast medium on X-ray scanning

Gadolinium has a higher atomic mass (64) than iodine (53). The K-edge absorption energy of gadolinium is 50.2 keV, which is in the absorbed wavelength range of the X-rays used by a CT scanner, suggesting that it has a high X-ray absorption ability. This study examined the effects of a gadolinium-based MRI contrast medium on the quality (mAs) and the quality (kVp) of radiation during a X-ray scan. A contrast medium phantom was manufactured after diluting the contrast medium to various concentrations. A CT scanner (Siemens, Somatom Senation 64, Germany) was used to obtain images by changing the quality of radiation from 80 kVp to 100, 120, and 140 kVp. At a constant quality of radiation of 120 kVp, the mAs was changed from 100 mAs to 200 and 300 mAs and images were obtained under each condition. The Hounsfield units (HUs) in a test tube were measured for analysis and comparison. The contrast enhancement by the contrast medium for CT scanning was 100% at a tube voltage of 80 kVp. The contrast enhancements at 100 kVp, 120 kVp, and 140 kVp were 93.8%, 87.7%, and 69.5%, respectively. In addition, although the quantity increased a fixed tube voltage, the HU of the test tube remained relatively constant, indicating that the absorption of the contrast medium had little association with the quantity of X-rays but had some correlation with the quality of radiation. A tube voltage of 80 kVp or lower is recommended when a MRI contrast medium is used CT scanning. When MRI scanning and X-ray scanning are conducted together, X-ray scanning should be performed first or after sufficient gadolinium contrast medium has been excreted.

     

Facile preparation of 7,11‐di(4‐nitrobenzenesulfonyl)‐diaza‐1,4‐dioxa‐7,11‐spiro[4,7]dodecan‐9‐one

Compound 1 as a key intermediate for the synthesis of 3,3,7,7‐tetrakis‐(difluoroamino)octahydro‐1,5‐dinitro‐1,5‐diazocine (HNFX) and 3,3‐bis(difluoroamino)octahydro‐1,5,7,7‐tetranitro‐1,5‐diazocine (TNFX) is described. Cycloalkylation of 3 with 1,3‐dibromopropan‐2‐ol ( 4 ) afforded 1,5‐protected‐1,5‐diazocine 2 , followed by chromic acid oxidation to ketone 1 in good yield.