Hepatitis A virus (HAV) proteinase 3C inhibits HAV IRES-dependent translation and cleaves the polypyrimidine tract-binding protein.

Hepatitis A virus (HAV) infection is still an important issue worldwide. A distinct set of viruses encode proteins that enhance viral cap-independent translation initiation driven by an internal ribosome entry site (IRES) and suppress cap-dependent host translation. Unlike cytolytic picornaviruses, replication of HAV does not cause host cell shut off, and it has been questioned whether HAV proteins interfere with its own and/or host translation. HAV proteins were coexpressed in Huh-7 cells with reporter genes whose translation was initiated by either cap-dependent or cap-independent mechanisms. Among the proteins tested, HAV proteinase 3C suppressed viral IRES-dependent translation. Furthermore, 3C cleaved the polypyrimidine tract-binding protein (PTB) whose interaction with the HAV IRES had been demonstrated previously. The combined results suggest that 3C-mediated cleavage of PTB might be involved in down-regulation of viral translation to give way to subsequent viral genome replication.

Effect of coal ash on hydrazine degradation under stirring and ultrasonic irradiation conditions.

The degradation of hydrazine (N(2)H(4)) with concentrations of 0.1-5.0 mmol/L was investigated as a function of amount of coal ash (0.0-5.0 wt%) under the stirring (300 rpm) and ultrasonic irradiation (200 kHz, 200 W) conditions. It was found that the rate of decrease in the hydrazine concentration depended upon an amount of coal ash under the stirring and ultrasonic irradiation condition. It was considered under the stirring condition that hydrazine was adsorbed and degraded partly on coal ash. Furthermore, the sonochemically formed OH radicals were more effective in the hydrazine degradation than stirring condition in the presence of an intermediate amount of coal ash (0.6-2.4 wt%), whereas the effect of OH radicals disappeared in the presence of coal ash more than 2.4 wt%.

The effect of pH on sonochemical degradation of hydrazine.

The degradation of hydrazine (N(2)H(4)) with concentrations of 0.1 and 1.0 mmol/L was investigated as a function of pH under the stirring (300 rpm) and ultrasonic irradiation (200 kHz, 200 W) conditions. It was found that the hydrazine degradation depended greatly upon pH under the ultrasonic irradiation condition, while it did not take place over the whole pH range (0.8-9) under the stirring condition. The hydrazine degradation was suppressed by the addition of tertial butyl alcohol (t-BuOH) known as a scavenger of OH radicals. This result suggested that OH radicals played an important role in the hydrazine degradation. The pH dependence of the hydrazine degradation was discussed in terms of a dissociating form of hydrazine depending upon pH and the effect of OH radicals.

Effect of coal ash on sonochemical degradation of phenol in water.

The influences of coal ash on the degradation of phenol in water were investigated under the stirring or ultrasonic irradiation conditions. Phenol solution (10mg/L, 100mL) was sonicated at 200 kHz and 200 W with or without coal ash (53-106 microm in particle size and concentration of 0.0-1.5 wt%). It was found that the sonochemical degradation of phenol in the presence of coal ash was faster than that in the absence of coal ash, and the optimum amount of coal ash was a maximum at 0.4-0.6 wt%. It was confirmed that the phenol degradation did not occur by the addition of hydrogen peroxide and nitric acid under the stirring conditions. The sonochemical degradation with coal ash was depressed by the addition of tertiary butyl alcohol as a radical scavenger. These results indicated that the coal ash accelerated the phenol degradation due to the increase in the amount of hydroxyl radicals under the ultrasonic irradiation. Since the coal ash used had a porous and uneven surface, which was observed by SEM, it was assumed that the coal ash led to the increase in the nucleation site for cavitation bubble due to its surface roughness.

X-ray magnetic circular dichroism imaging with hard X-rays.

X-ray polarization-contrast images resulting from X-ray magnetic circular dichroism (XMCD) in the hard X-ray region have been successfully recorded for the first time. The apparatus used consisted of an X-ray polarizer, double X-ray phase retarders, and a high-spatial-resolution X-ray charge-coupled-device detector. The sample used was a hexagonal-close-packed cobalt polycrystal foil having a thickness of about 4 microns. The X-ray polarization-contrast image resulting from XMCD was observed at a photon energy of 10 eV above the cobalt K-absorption edge (7709 eV). The observed contrast in the image was reversed by inversion of the magnetic field. Furthermore, the contrast was reversed again at a photon energy of 32 eV above the cobalt K-absorption edge.

X-ray double phase retarders to compensate for off-axis aberration.

An X-ray double phase retarder system composed of two transmission-type phase retarders is proposed and developed in order to compensate for off-axis aberration (phase-shift inhomogeneity due to angular divergence of incident X-rays). The scattering planes of the two phase retarders are set to be inclined by 45 degrees with respect to the plane of incident polarization, but the two phase retarders give Bragg reflections in opposite directions. By using this X-ray optical system, vertically polarized X-rays with a 0.99 degree of linear polarization were obtained from horizontally polarized synchrotron radiation with a horizontal beam divergence of 20 arcsec (0.1 mrad). This value is favorably compared with the value of 0.87 which was obtained using a conventional single phase retarder of identical total thickness, 627 microns. The comparison was made at the nickel K-absorption edge (8333 eV) with the condition that 47% of incident X-rays were transmitted through the two phase retarder crystals. The crystals were (100)-oriented diamond plates giving asymmetric 111 Laue reflections.

Demonstration of X-ray linear dichroism imaging with hard X-rays.

X-ray polarization-contrast images resulting from X-ray linear dichroism (XLD) in the hard X-ray region have been successfully recorded for the first time. The apparatus used consisted of an X-ray polarizer, double X-ray phase retarders and a high-spatial-resolution X-ray charge-coupled device (CCD) detector. The sample used was a hexagonal close packed (h.c.p.) cobalt single-crystal foil of thickness about 12 microm. The experiment was performed at X-ray energies of 23 and 29 eV above the cobalt K edge (7709 eV), at which the maximum linear dichroisms (approximately 3%) were observed, with their signs reversed, in the XLD spectrum measured with quadruple X-ray phase retarders. The contrasts in the images at the two X-ray energies were reversed as a result of the XLD in the sample. Furthermore, the values of the contrast in the images arising from the linear dichroism (approximately 3%) were in good agreement with those yielded by the XLD spectrum.

Tunable X-ray polarization reflector with perfect crystals.

The possibility of a transmission-type X-ray linear polarizer is investigated using a thin Bragg reflector as a polarizing filter. In this device, the transmitted beam (rather than the Bragg-reflected beam) is the useful output of the device. Consequently, the position and the direction of the transmitted beam are unchanged as the energy is changed, or even when the polarization direction to be filtered out is changed. Theoretical considerations as well as preliminary transmissivity measurements are presented. The use of perfect crystals of silicon and diamond is examined. A polarization ratio, defined as I(H)/I(V), higher than 10(5) was observed in experiments to measure the performance characteristics of the proposed X-ray polarizing reflector. The transmission-type X-ray linear polarizer is well suited for spectroscopic measurements with polarized X-rays.

Transmission-type X-ray linear polarizer with perfect crystals.

Even though conventional X-ray polarizers with multiple-reflection channel-cut structures perform well, they suffer from the disadvantage that the polarized beam is non-stationary as the energy is scanned. In this paper the possibility of using a thin Bragg reflector as a polarizing filter is investigated, so that the transmitted beam (rather than the Bragg-reflected beam) is used. Consequently, the position and direction of the transmitted beam are unchanged as the energy is changed, or even when the polarization direction to be filtered out is changed. Theoretical considerations as well as experimental results on the performance characteristics of the proposed transmission-type X-ray linear polarizer are presented. A polarization ratio, defined as I(H)/I(V), higher than 10(5) was obtained.

X-ray linear birefringence and linear dichroism in a cobalt crystal measured with a tunable X-ray polarimeter.

X-ray linear birefringence and linear dichroism spectra have been measured simultaneously and quantitatively for the first time. The sample was a hexagonal cobalt single-crystal foil. The apparatus used was an energy-tunable X-ray polarimeter, consisting of a polarizer, a phase retarder and an analyser. The X-ray energy was scanned over a range of 350 eV near the K-absorption edge. The Kramers-Kronig relation between the refraction and absorption anisotropy has been confirmed on an absolute scale. The phase-difference sensitivity of the polarimeter as a polarization inferometer is as small as 2pi/10000, which is about 100 times smaller than that of the Bonse-Hart inferometer.

X-ray triple refraction and triple absorption in a cobalt-complex crystal.

X-ray triple refraction and triple absorption have been quantitatively measured for the first time. The samples were (100)-, (010)- and (001)-oriented plates of a cobalt-complex monoclinic crystal. The apparatus used was an energy-tunable X-ray polarimeter with a phase retarder. The X-ray energy was scanned over a range of 150 eV near the cobalt K-absorption edge. Both the spectra of ellipticity and rotation of polarization were completely different for each crystal plate, which revealed that the biaxial crystal had three refractive indices and three absorption coefficients in the X-ray region. The Kramers-Kronig relation between the real and imaginary parts of the dielectric anisotropy has been quantitatively confirmed for all three different orientations.

Sonochemical formation of gold particles in aqueous solution.

Gold(III) ions in aqueous solutions of NaAuCl4 were reduced to form gold particles by ultrasonic irradiation. The rate of formation of gold particles was accelerated in the presence of certain organic additives such as surfactants, water-soluble polymers and aliphatic alcohols and ketones. The rates of formation of gold particles from 1 mM Au(III) ions in pure water were 3 microM min-1 under argon atmosphere and approximately zero under air, and in solutions containing additive the rates were 9-133 microM min-1 under argon and 8-40 microM min-1 under air. Surfactants stabilized the particles as colloidal state for more than several months. The rates of formation of both hydrogen atoms and hydroxyl radicals were estimated to be equal to 25 microM min-1 in the sonolysis of pure water under argon. Three reaction pathways leading to the reduction of metal ions were proposed: (1) reduction by hydrogen atoms; (2) reduction by reducing radicals formed via reactions of hydroxyl radicals or hydrogen atoms with the additives; (3) reduction by radicals formed from thermal reaction of the additives at the interfacial region between cavitation bubbles and bulk solution and/or in the cavities. The order of the contribution of these three pathways to the reduction of gold ions was (3) > (2) > (1) in most cases. The number averages of the size of gold particles formed in surfactant solutions under argon atmosphere were about 10 nm with a fairly narrow size distribution.

Clinical features of 53 cases with pustulotic arthro-osteitis.

We have described clinical features of 53 cases with pustulotic arthro-osteitis. Anterior chest wall symptoms such as intersterno-costoclavicular or manubriosternal lesions were observed in all of 53 cases. Spondylitis or spondylodiscitis was found in 18 cases. Sacroiliitis resembling ankylosing spondylitis was seen in 7 cases. Peripheral inflammatory arthritis was seen in 14 cases, which were of nonerosive, of oligoarthritis type, and cured within 1 to 2 months, leaving no residue. HLA B27 was never found, and RAW factor was negative. Histological examinations revealed nonspecific chronic inflammation of bone and soft tissue. Pustulotic arthro-osteitis is apparently distinct from known rheumatic diseases such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and Reiter's disease. We have proposed that this condition should be classified as a member of the "seronegative spondylo-arthritis' group as designated by Wright and Moll.

HLA DR4 and rheumatoid arthritis in Japanese people.

Eighty-eight Japanese patients with rheumatoid arthritis and 104 normal Japanese persons were typed for HLA A, B, C, and DR antigens. The frequency of HLA DR4 was 70.5% in patients compared with 46.1% in normal controls (P less than 0.001). However, a sex difference in the frequency of HLA DR4 in patients was noted. HLA DR4 was found in 80.6% of male patients, which was highly significant compared with controls (P less than 0.0005), while only a borderline increase of 60.5% was found in female patients (P less than 0.05). In addition, the frequency of HLA DR2 was remarkably low in male patients. These suggest the possible heterogeneity of rheumatoid arthritis in Japanese.

[[HLA in rheumatoid arthritis (author's transl)].

Despite many reports on the association between ankylosing spondylitis and HLA-B27, most studies have failed to find a significant relationship between HLA-A or B antigen and rheumatoid arthritis. Stastny, however, showed a significantly high frequency of HLA-Dw4 in rheumatoid arthritis in 1976. The study of HLA antigens in Japanese patients with rheumatoid arthritis are thought to be significant in view of the pathogenesis of disease. Eighty-eight Japanese patients with "definite" or " classical" rheumatoid arthritis according to the ARA criteria and 104 normal individuals were typed for serologically detectable HLA-A, B, C, and D antigens. Though small discrepancies were observed in several of the HLA-A, B, and C, antigens, they were not definitely significant. The frequency of HLA-DR4 increased to 70.5% in patients compared to 46.1% in the control (i.e. normal) group (p less than 0.001). However, the frequency increased to 80.6% in male patients (p less than 0.0005). Of interest was the significantly high frequency of HLA-DR4 in males, compared to the low frequency of HLA-DR2 (p less than 0.02). Rheumatoid patients were subdivided into different groups according to the year of onset, the presence of the the rheumatoid factor or rheumatoid nodules, the functional grade and treatment. There were no significant differences in the frequency of HLA-DR4 among subgroups. The results indicate that rheumatoid arthritis, especially in males, is associated with genes of the HLA-D region and that immunogenetic factors linked to HLA have an important role in its pathogenesis.

[Comparative study on rat arthritis induced by various immune mechanisms (author's transl)].

Experimental arthritis was induced in rats by the use of horse ferritin as an antigen. The pathological findings were studied and the mechanisms of inflammation were analyzed. Arthritis was induced through various mode of actions: 1. Arthus reaction (antigen-induced arthritis). 2. Passive Arthus reaction. 3. Reverse passive Arthus reaction. 4. Arthritis induced by intra-articular injection of immune complex, by either single shot or repeated injections. 5. Arthritis induced by anamnestic reaction. Arthritis induced by repeated injections of immune complex or that induced by anamnestic reaction exhibited mild chronic synovitis characterized by round cell infiltration without detectable acute phase of inflammation. Arthritis induced through other immunological mechanisms revealed a sequential course of acute synovitis characterized by accumulation of polymorphonuclear leucocytes (PMN) followed by gradual disappearance of PMN and alternative increase of round cells or plasma cells and proliferation of synovial lining cells. All types of arthritis subsided with mild fibrosis of the synovial tissue without lasting over a significantly long time. Although the successful production of a long-lasting chronic arthritis has been reported in rabbits, it was impossible to induce such long standing arthritis through this experiment. The chronicity of the arthritis induced through immunological mechanism may not simply be due to the long-standing retention of immune complex within the involved joint but also due to other factors such as the species of the test animals, the nature of antigen used and local factors produced through acute joint inflammation.