Brain acetylhydrolase that inactivates platelet-activating factor is a G-protein-like trimer

The platelet-activating factor PAF (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent lipid first messenger active in general cell activation, fertilization, inflammatory and allergic reactions, asthma, HIV pathogenesis, carcinogenesis, and apoptosis. There is substantial evidence that PAF is involved in intracellular signalling, but the pathways are poorly understood. Inactivation of PAF is carried out by specific intra- and extracellular acetylhydrolases (PAF-AHs), a subfamily of phospholipases A2 that remove the sn-2 acetyl group. Mammalian brain contains at least three intracellular isoforms, of which PAF-AH(Ib) is the best characterized. This isoform contains a heterodimer of two homologous catalytic subunits alpha1 and alpha2, each of relative molecular mass 26K, and a non-catalytic 45K beta-subunit, a homologue of the beta-subunit of trimeric G proteins. We now report the crystal structure of the bovine alpha1 subunit of PAF-AH(Ib) at 1.7 A resolution in complex with a reaction product, acetate. The tertiary fold of this protein is closely reminiscent of that found in p21(ras) and other GTPases. The active site is made up of a trypsin-like triad of Ser 47, His 195 and Asp 192. Thus, the intact PAF-AH(Ib) molecule is an unusual G-protein-like (alpha1/alpha2)beta trimer.     

Yielding behavior and its effect on uniform elongation in IF steel with various grain sizes

In the present study, IF steel specimens with different grain sizes ranging from 12 to 0.45 μm were fabricated by accumulative roll-bonding process and subsequent annealing. Tensile tests revealed that by decreasing the mean grain size down to an ultrafine range smaller than approximately 1.5 μm, yielding behavior of the IF steel gradually changed from continuous yielding to discontinuous yielding. An abrupt loss in the uniform elongation occurred, when the average grain size was smaller than about 1 μm. Hall–Petch analysis on the yield stress and uniform elongation implied that the abrupt loss in the uniform elongation in the UFG grain size range corresponded to the appearance of the discontinuous yielding behavior. As it has been found in many UFG materials, discontinuous yielding is believed to be a unique mechanical behavior of UFG materials, and it has significant importance on the uniform elongation of UFG materials.     

添加合金元素对奥氏体不锈钢等离子渗氮和渗碳的影响

奥氏体不锈钢众所周知有良好的耐蚀性,但是在工业上没有用于承受摩擦的工件上,因为它的硬度低,摩擦磨损性能差。奥氏体不锈钢经低温等离子体渗氮或渗碳能生成一层特殊的氮化物或碳化物层,称为S相,它具有高的硬度和优良的耐蚀性。这项研究中各种奥氏体不锈钢都经低温等离子体渗氮或渗碳,用各种分析技术研究了添加合金元素对S相特性的影响,用了光学显微镜和电子显微镜观察,做了X射线衍射分析,在5%H2SO4溶液中测量阳极极化,用球对平面摩擦装置做摩擦磨损测试。氮化物或碳化物层厚度随处理温度增加而加厚,AISI316钢上生成的渗层厚度是所有的基体钢材中最厚的。超过临界温度,由于氮化铬工碳化铬沉淀使耐蚀性降低。临界温度由渗氮的基材决定。另一方面,在渗碳层中临界温度不随基材变化。大部分样品上S相层的耐蚀性比没有处理的不锈钢的低。但是,AISI316和JIS-SUS304J3钢在400℃渗碳后都有和未处理钢一样优良的耐蚀性。每种不锈钢经渗氮或渗碳后耐磨性都有明显的改进。     

Zinc oxide-coated plasmonic chip modified with a bispecific antibody for sensitive detection of a fluorescent labeled-antigen

A plasmonic biosensor chip of silver-coated PMMA grating with a zinc oxide (ZnO) overlayer is fabricated for surface plasmon field-enhanced fluorescence (SPF) detection of Cy5-labeled green fluorescent protein (GFP). A bispecific antibody (anti-GFP x anti-ZnO antibody) prepared in our lab is densely immobilized on the sensor chip for GFP detection. The sensitivity of the plasmonic biosensors is improved due to densely packed antibodies and ZnO-coating that suppresses nonspecific protein adsorption and fluorescent quenching. With the ZnO-coated plasmonic chip, Cy5-labeled GFP of 10 pM can be detected through SPF. This sensitivity is 100 higher compared with the normal fluorescent detection on a ZnO-coated glass slide.     

Half-data-page insertion method for increasing recording density in angular multiplexing holographic memory

We have developed a method to use a half-size data page between two full-size data pages to increase the recording density in angular multiplexing holographic memory up to 1.5× as much as the conventional angular multiplexing sequence. In our recording sequence, the full- and half-size data pages are alternately multiplexed. This is because each plane wave from various points in a data page has different angular selectivity. A half-size data page has higher angular selectivity than a full-size data page. The required angular intervals were estimated by numerical simulation taking holographic medium tilt into account. Also, an angular multiplexing experiment using the half-data-page insertion method resulted in a low bit error rate of the order of 10(-3), which is sufficient for practical use.     

Control of wetting on Ti-based bulk metallic glass surfaces by a hydrothermal method

The surfaces of the Ti-based bulk metallic glasses (Ti₅₀Ni₂₀Cu₂₅Sn₅) were modified by a hydrothermal method using sodium hydroxide (NaOH) solution, and the surface wettability was investigated. No reflections were observed in the XRD patterns of the NaOH-treated samples even though there was a clear change of the color, indicating formation of amorphous oxide phases. The Raman spectra showed peaks attributed to sodium titanate compounds (Na–O–Ti) and titanium oxide. Some of the samples were observed to have a very rough surface microstructure such as a “house-of-cards” or leaf-like structure. The water contact angle of the treated samples decreased with increasing treatment temperature and time. These results indicate that the wettability of the sample surface was able to be controlled from hydrophobic to hydrophilic by changing the conditions of the hydrothermal treatment.     

Synthesis of non-equilibrium phases in immiscible metals mechanically mixed by high pressure torsion

The structural changes in mechanically mixed metals of immiscible combinations of elements caused by bulk mechanical alloying (MA) through the use of high pressure torsion (HPT) were investigated in Ag–Ni and Nb–Zr systems. There was no alloying between Ag and Ni on atomic scale even after 100 rotations of HPT. On the other hand, the β-Zr phase started to appear after HPT 2 rotations in the Nb–Zr system, even though β-Zr is a high temperature phase. Further, Nb and Zr were completely mixed to form a bcc structured single phase after HPT 100 rotations. The sequence of alloying in the Nb–Zr system during HPT was discussed. These results clearly suggest that non-equilibrium phases can form in the Nb–Zr system by bulk MA by the use of HPT.     

Increase in mucosal and connective tissue-type mast cells in the stomach with acetic acid-induced ulcer in rat

The fluorescent probe furaptra shows increases and decreases in the concentration of free magnesium ion, [Mg2+], in the mitochondrial matrix with changes in total Mg2+ and ligand availability. The factors involved in the calibration of these fluorescence changes in terms of absolute [Mg2+] have been investigated. The affinity of furaptra for Mg2+ is highly dependent on both temperature and ionic strength. The Kd for Mg-furaptra in solution in 100 mM KCl was found to be 2.1 +/- 0.1 mM at 25 degrees C. The use of this Kd to calculate matrix [Mg2+] is more reliable than in situ Kd measurements because ionophores, such as BrA23187 and ionomycin, do not equilibrate external Mg2+ with the matrix in an acceptable way. Furaptra is present at high concentrations (up to 500 microM) in the matrix when introduced by hydrolysis of the acetoxymethyl ester. However, absorbance spectra of aqueous solutions show no evidence of dimerization of the probe or other changes in properties at these concentrations. Fluorescence intensity at 340 nmex is strongly attenuated for matrix-sequestered furaptra, mag-fura-5, and mag-indo-1. This appears to result in part from preferential binding of the Mg-probe to mitochondrial proteins. The fluorescence of uncomplexed furaptra at 375-380 nmex seems unaffected by protein binding, however, and changes in intensity in this region of the spectrum can be used in conjunction with the Kd found in aqueous solution to estimate matrix [Mg2+]. The presence of secondary equilibria, such as protein binding, and possible changes in ionic strength may undermine exact quantitation by this method. However, values for matrix [Mg2+] obtained in this way (0.5 to 0.7 mM) correspond well to estimates by other available methods and each of these methods suffers from comparable uncertainties.     

Stress induced urinary incontinence in patients with spinocerebellar degeneration

To better understand genetic alterations in atypical adenomatous hyperplasia (AAH) of the prostate, we examined the prevalence of allelic imbalance at 5 microsatellite polymorphic markers on chromosomes 7q31-35, 8p12-21, 8p22, 8q22.2, and 18q12.2 from 15 patients with AAH. DNA samples were obtained from formalin-fixed paraffin-embedded sections using tissue microdissection. We found allelic imbalance in 7 of 15 (47%) cases of AAH. Genetic changes that commonly occur in early prostatic carcinogenesis and prostate carcinoma are found in AAH. Current data provide evidence of a genetic link between some cases of AAH and carcinoma.     

A 99-mm2 0.7-W single-chip MPEG-2 422P@ML video, audio,and system encoder with a 64-Mb embedded DRAM for portable 422P@HLencoder system

A scalable single-chip 422P@ML MPEG-2 video, audio, and system encoder LSI for portable 422P@HL system is described. The encoder LSI is implemented using 0.13-μm embedded DRAM technology. It integrates 3-M logic gates and 64-Mb DRAM in an area of 99-mm². The power consumption is suppressed to 0.7 W by adopting a low-power DRAM core. It performs real-time 422P@ML video encoding, audio encoding, and system encoding with no external DRAM. Furthermore, the encoder LSI realizes a 422P@HL video encoder with multichip configuration, due to its scalable architecture. This results in a PC-card size 422P@HL encoder for portable HDTV codec system