Interaction of NADPH-adrenodoxin reductase with NADP+ as studied by pulse radiolysis

The reduction of flavin in NADH--adrenodoxin reductase by the hydrated electron (eaq-) was investigated by pulse radiolysis. The eaq- reduced directly the flavin of the reductase to form a blue semiquinone of the enzyme. Subsequently, the semiquinone decayed by dismutation to form the oxidized and fully reduced forms of the enzyme with a second-order rate constant of 4.4 x 10(4) M-1 s-1. In the presence of equimolar NADP+, the decay of eaq- accompanied an absorption increase at 400 nm, the spectrum of which, formed transiently, is identical to that of NADP radical (NADP.). Subsequently, the transient species decayed concomitantly with the formation of the semiquinone. The rate constant in the formation of the semiquinone was independent of the concentration of the enzyme (6.1 x 10(4) s-1 at pH 7.5). From these results, it is concluded that eaq- reacts with NADP+ bound to the enzyme to form NADP. initially, and subsequently, an electron flows from the NADP. to the flavin by an intracomplex electron transfer. A similar result was obtained in the reaction of CO2- or N-methylnicotinamide radical with the NADP(+)-adrenodoxin reductase complex. These results suggest that the nicotinamide moiety of NADP+ bound to the enzyme is accessible to the solvent and masks the flavin completely.     

Expression of glutathione-peroxidase (GSH-PO) in the rat ventral prostate--effect of castration and administration of testosterone

This series retrospectively reviewed 3657 patients who received thyroid ultrasonography with fine-needle aspiration cytological (FNAC) examinations at Chang Gung Memorial Hospital during the period from January 1, 1993 to December 31, 1993. Thyroid ultrasonography studies were performed using a real-time ultrasonographic machine with a 10 MHz transducer. The aspirates were air dried and stained by the Romanowsky-based Liu method. Three hundred seventy-eight cases (10.3%) received surgical treatment after the ultrasonographic and FNAC examinations. Benign lesions were diagnosed in 269 patients. Thyroid malignancy was confirmed histopathologically in 109 cases including 76 papillary thyroid carcinomas, 17 follicular carcinomas, 5 medullary thyroid carcinomas, 3 anaplastic carcinomas, 3 Hürthle cell carcinomas, and 3 lymphomas. Another 2 cases were metastatic cancer to thyroid. The results demonstrated that 28.8% of the surgically treated patients had histopathologically proven malignancies. The incidence of thyroid malignancy was 2.98% in this study. The sensitivity of the cytological diagnosis was 79.80% and the specificity was 98.66%. The positive predictive value was 96.34%. Negative predictive value was 91.70%. The false negative index was 20.20%. The diagnostic accuracy was 92.89%. Thyroid ultrasonography with the FNAC can provide high specificity and sensitivity in differentiating malignant lesions from benign.     

A case of sporadic acute type A hepatitis associated with acute renal failure

We report a case of sporadic acute type A hepatitis associated with acute renal failure, due to mesangioproliferative glomerulonephritis and interstitial nephritis. A 42 year-old-man was admitted to Mitsui Memorial Hospital because of jaundice and oliguria with fever in February, 1989. His serum creatinine was 12.2 mg/dl, BUN 87 mg/dl, GOT 57 U/l and GPT 358 U/l. The serum IgM antibody to hepatitis A virus was positive, which indicated recent infection with hepatitis A virus. Hemodialysis and steroidal therapy were started, and the patient's acute renal failure and liver dysfunction ameliorated within one month. Light microscopic examinations showed an increased number of mesangial cells and an increased amount of mesangial matrix, and also showed inflammatory cell invasion in the interstitium. Electron microscopic examinations showed proliferation of mesangial cells and matrix, and a dense deposit along the basement membrane. On immunofluoresent studies, fine granular deposits of IgA and Clq were observed in the mesangium.     

Direct measurements of gas diffusivity in a washcoat layer under steady state conditions at ambient temperature

A method for directly measuring gas diffusivity in a washcoat layer was established by preparing a simulated washcoat layer and modifying a Wicke–Kallenbach type counter-current diffusion cell. Three pairs of gases, N₂Ar, CO₂Ar and C₃H₈Ar, were used in the measurements. It was found to be possible to evaluate the pore-transport parameters of the washcoat layer based on the mean transport pore model and the modified Stefan–Maxwell equation. Analysis of the gas diffusion mechanism in the washcoat layer showed that bulk and Knudsen diffusion took place simultaneously, and the percentage value of the contribution by Knudsen transport to net diffusion transport was evaluated.     

THE BEHAVIOR OF MICROSCALED BROWNIAN PARTICLES IN A CYLINDER UNDER NATURAL-AND MAGNETIC-CONVECTION FLOW FIELD OF AIR

ABSTRACT

The behavior of carbon particles (mostly 1μm in diameter) in a natural-convection flow field of air and a magnetic field was studied numerically. One thousand particles were released randomly in a vertical cylinder whose height is equal to its radius. The bottom of the enclosure was heated and the side wall was cooled. A coil with electric current was set coaxially with the cylindrical enclosure. For the nano- and micro- order particles, Brownian motion was taken into consideration and the Langevin equation was solved for the particles. The results show that the behavior of 1-μm-sized particles depends mainly on the flow field. The magnetic field changes the flow mode of natural convection of air due to the paramagnetic susceptibility of oxygen and affects the behavior of the particles indirectly. The coil level, the aspect ratio of the cylinder, and the geometric arrangement of the hot and cold plates produce different flow fields, which makes the behavior of the particles different. The particles larger than 1μm circulate along the streak lines or cluster, but those smaller than 1μm are strongly driven by the Brownian motion.     

Modulated structure and magnetic properties of age-hardenable Fe-Mn-Al-C alloys

Microstructural changes in the age-hardenable Fe-(30 to 34) wt pct Mn-(8 to 11) wt pct Al-(0.9 to 1.0) wt pct C alloys during aging in the temperature range between 773 and 823 K have been investigated by means of transmission electron microscopy (TEM) and X-ray diffraction. The wavelength of the modulated structure was found to be nearly constant for short aging times and then to increase on further aging, whereas the compositional modulation amplitude was found to increase rapidly from the beginning of aging. The growth of a spinodally modulated structure along the orthogonal «100» directions results in a periodic arrangement of the κ-carbide precipitates, (Fe, Mn)₃AlC_x, in the austenite matrix. The increases in hardness and residual and saturation inductions in the early stage of aging were in accord with the increase in the amplitude.     

Characterization of a new mixed oxide catalyst derived from hydrogen storage alloy

A mixed oxide catalyst was prepared from a binary hydrogen storage alloy, Mg₂Cu. Oxidation of Mg₂Cu alloy gave mixed oxides of MgO and CuO, which showed high activity and high selectivity for the synthesis of alcohols from methyl linoleate. On the other hand, a catalyst prepared by the coprecipitation method deactivated with time. The nature of the catalytically active site was discussed on the basis of characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and infrared analysis (I.R.). The difference between these two catalysts could be attributed to differences in the co-ordination number of copper species at the surface.     

Phase relations and crystal chemistry in the ternary PrO1.5-UO2-O2 system

Phase relations and defect structures were studied in a PrO_1.5-UO₂-O₂ ternary system in the temperature range from 1200 to 1500°C. Phases and compositions of the products heated in either air, helium or vacuum were examined by $\text{X-}\text{ray}$ diffraction and chemical analysis, respectively. The regions of existence of solid solution having fluorite type structure, of rhombohedral phase and of A-type rare earth sesquioxide phase were determined. It was found that these phase relations could be classified by the mean valency of uranium and the type of oxygen defects. The change of cubic lattice parameter of the solid solution, $\text{Pr}{}_{\mathrm{y}}\text{U}{}_{\mathrm{1?y}}\text{O}{}_{\mathrm{2+x}}$, in single phase region ($\text{0 ≤ y ≤ 0.7}$) was expressed as linear equations of $\text{x}$ and $\text{y}$: $\text{a = 5.4704?0.127x ?0.007y, for x ≥ 0}$ and $\text{a = 5.4704?0.397x?0.007y, for x < 0}$. The change of lattice parameters was discussed in some detail.