Role of nitric oxide in rat nephrotoxic nephritis: comparison between inducible and constitutive nitric oxide synthase

Nitric oxide (NO), generated by inducible NO synthase (iNOS) in migrating macrophages, is increased in glomerulonephritis. This study investigates the effect of NO inhibition on rat nephrotoxic nephritis (NTN) to clarify the role of NO production in glomerular damage. NTN was induced in Sprague Dawley rats by an injection of an anti-glomerular basement membrane (GBM) antibody. Urinary nitrite excretion and nitrite release from kidney slices (5.47 +/- 1.19 versus 2.15 +/- 0.73 nmol/mg protein, NTN versus Control, P < 0.05) were increased in NTN on day 2. Glomerular macrophage infiltration and intercellular adhesion molecule (ICAM)-1 expression increased from day 2. iNOS expression was increased in interstitial macrophages. Glomerular endothelial cell NOS (ecNOS) expression evaluated by counting immunogold particles along GBM was suppressed (0.06 +/- 0.02 versus 0.35 +/- 0.04 gold/micron GBM, P < 0.0001). Glomerular damage developed progressively. NG-nitro-L-arginine methyl ester (L-NAME), which inhibits both iNOS and ecNOS and aminoguanidine (AG), a relatively selective inhibitor for iNOS, equally suppressed nitrite in urine and renal tissue. Glomerular ICAM-1 expression and macrophage infiltration were reduced by L-NAME, but not by AG. Expression of ecNOS was significantly increased by L-NAME (0.91 +/- 0.08, P < 0.0001 versus NTN), but slightly by AG (0.18 +/- 0.04). AG significantly and L-NAME slightly attenuated the glomerular damage at day 4. In conclusion, suppression of iNOS prevents glomerular damage in the early stage of NTN. Treatment by L-NAME reduces macrophage infiltration by suppression of ICAM-1 expression, which may be explained by an increase in ecNOS expression.     

Substrate-binding lipoprotein of the cyanobacterium Synechococcus sp. strain PCC 7942 involved in the transport of nitrate and nitrite

Of the four genes (nrtABCD) required for active transport of nitrate in the cyanobacterium Synechococcus sp. strain PCC 7942, nrtBCD encode membrane components of an ATP-binding cassette transporter involved in the transport of nitrite as well as of nitrate, whereas nrtA encodes a 45-kDa cytoplasmic membrane protein, the biochemical function of which remains unclear. Characterization of the nrtA deletional mutants showed that the 45-kDa protein is essential for the functioning of the nitrate/nitrite transporter. A truncated NrtA protein lacking the N-terminal 81 amino acids, expressed in Escherichia coli cells as a histidine-tagged soluble protein, was shown to bind nitrate and nitrite with high affinity (Kd = 0.3 microM). Immunoblotting analysis using the antibody against the 45-kDa protein revealed a 48-kDa precursor of the protein, which accumulated in the cyanobacterial cells treated with globomycin, an antibiotic that specifically inhibits cleavage of the signal peptide of lipoprotein precursors. These findings indicated that the nrtA gene product is a nitrate- and nitrite-binding lipoprotein. The N-terminal sequences of putative cyanobacterial substrate-binding proteins suggested that lipoprotein modification of substrate-binding proteins of ATP-binding cassette transporters is common in cyanobacteria.     

Nonlinear repetitive control with application to trajectory control of manipulators

In this article, a new control scheme named repetitive control is proposed for a class of nonlinear systems described by x(t) = Ax(t) + Bu(t) + n(x(t)) and y(t) = Cx(t), in which the controlled variables follow periodic reference commands. The stability condition is derived by applying the passivity theorem. We show how to apply the repetitive control scheme to the trajectory control of a manipulator. A simple repetitive control scheme is developed for the trajectory control of a manipulator by using nonlinear compensation and feedbacks of position and velocity signals. Experimental results for a three link manipulator verify that the proposed repetitive control reduces the tracking error to a very low level.     

Oxidative coupling of methane over CaO-MgO mixed oxide

Mixed oxide catalyst prepared by co-precipitating magnesium oxide and calcium oxide showed an excellent activity for the oxidative coupling of methane. The high performances were presumed to arise from the high basicity of the mixed oxide.     

Clonality in hepatocellular carcinoma: analysis of methylation pattern of polymorphic X-chromosome-linked phosphoglycerate kinase gene in females

Analysis of X-chromosome inactivation patterns in women has been used to assess the clonality of various tumors. In this report, we analyzed 27 liver tumors in women, including 18 samples obtained by the performance of ultrasonically guided thin-needle biopsies. By analysis of the heterogeneity of phosphoglycerate kinase gene, 11 of 27 (41%) cases were found to be heterozygous at the gene. Of these informative 11 cases with liver tumors, 7 cases were "large" tumors (> 25 mm in diameter) and 4 cases were "small" tumors (< 25 mm in diameter). All 7 large tumors showed monoclonal patterns by the phosphoglycerate kinase gene analysis. Of the 4 small tumors, 2 showed monoclonal, and 2 showed polyclonal patterns. The 2 with monoclonal patterns were pathologically diagnosed as hepatocellular carcinoma despite their small sizes (20 mm and 23 mm). Of the two with polyclonal patterns, the smallest one (15 mm) was diagnosed as benign adenomatous hyperplasia, and the other as hepatocellular carcinoma heavily infiltrated by lymphocytes. These data suggest that analysis of the methylation pattern of the phosphoglycerate kinase gene may be helpful on rare occasions in elucidating the nature of liver tumors but must in fact be used in conjunction with histological appearances to avoid errors secondary to inflammatory infiltrates.     

Assessment of the antioxidant capacity of a fermented grain food product,Antioxidant Biofactor (AOB), by using pyranine and pyrogallol red as a combined probe

The role of antioxidants contained in foods, beverages, and supplements against oxidative stress has received much attention. The capacity of antioxidants has been assessed by various methods. In this study, the antioxidant capacity of a complex mixture of fermented grains has been assessed by using two probes, pyranine and pyrogallol red (PGR). A supplement commercialised as Antioxidant Biofactor, AOB, was used as a substrate. The extracts from AOB obtained with water and dimethylsulphoxide (DMSO) inhibited the free radical-induced consumption of pyranine and PGR in a concentration-dependent manner. They also suppressed the free radical-induced oxidation of human plasma. It was estimated that 1 g of AOB contained, as Trolox equivalent, roughly 0.13 and 0.24 mmol (2.5 and 4.7 wt%) antioxidants, which could be extracted by water and DMSO, respectively. This study shows that the combination of the above two probes is useful for assessing the total content and activity of antioxidants contained in complex mixtures.     

Oxygen release behavior of metastable tetragonal t′meta-(Ce0.5Zr0.5)2 phases prepared by reduction and successive oxidation of t′ phase

Tetragonal CaF₂-related-type t′-/Ce_0.5Zr_0.5)O₂ phase was reduced at 773 K ≤ T_red. ≤ 1073 K to prepare precursors with various oxygen compositions: Ce₂Zr₂O_712d /0.111 < δ < 0.379). Metastable tetragonal t^′_meta-(Ce_0.5Zr_0.5)O₂ phases were prepared by oxidizing in O₂ at 873 K the precursors, and subjected to evolved oxygen gas analysis by heating the samples at a constant rate. When the precursor was prepared at T_red: ? 773 K; i.e. δ ? 0:379; the oxygen release behavior of the tetragonal phase agreed approximately with that of the t^′. For δ < 0.29, distinct features of the t^′_meta-(Ce_0.5Zr_0.5)O₂ appeared in the XRD results and Raman spectra. The temperature exhibiting the maximum release rate of oxygen from the t^′_meta became lower with decreasing the d value. It could be concluded that the thermodynamic behavior of the t^′_meta is related closely to the precursor composition and becomes more unstable with decrease in the δ value. The t^′ and t^′_meta phases with disordered arrangement of Ce and Zr ions may belong to the same space group; nevertheless, difference in the random arrays of the Ce and Zr ions was suggested on the basis of the present experimental results.     

Oxygen release behaviour of Ce(1−x)ZrxO2 powders and appearance of Ce(8−4y)Zr4yO(14−δ) solid solution in the ZrO2–CeO2–CeO1.5 system

To clarify the existence of metastable phases in the ZrO₂–CeO₂–CeO_1.5 system, evolved-oxygen gas analyses, (EGA), by heating a single phase of t′ and t″ (Ce_(1−x)Zr_xO₂) with various compositions, x, in a reducing gas and successive oxidation were carried out repeatedly. The oxygen release behaviour of the t′ and t″ phases was very complicated. The single κ phases, (Ce_(1−x)Zr_xO₂) with the composition, x=0.5 and 0.6, which were obtained by oxidizing the resulting pyrochlore as a precursor in O₂ gas at 873 K, exhibited a sharp oxygen release at the lowest temperature; the composition range of κ phase may be x=0.450.65. A new tetragonal phase t*, (Ce_(1−x)Zr_xO₂), which was attained by cyclic redox process together with annealing in O₂ gas at 1323 or 1423 K, exhibited a sharp oxygen release at the highest temperature; the composition range of t* phase may be as wide as x=0.200.65. A metastable solid solution expressed by a chemical formula of Ce_(8−4y)Zr_4yO_(14−δ) (y=01) possessing a CaF₂-related structure appeared on deoxidation of the t* phase. A ternary phase diagram containing the t* and Ce_(8−4y)Zr_4yO_(14−δ) solid solution was proposed.     

Electrical conductivity of metastable κ-CeZrO4 phase possessing ordered arrangement of Ce and Zr ions

Electrical conductivity σ_t of metastable κ-CeZrO₄ possessing ordered arrangement of Ce and Zr ions in a manner similar to a pyrochlore-type was measured as a function of temperature and time, and compared with tetragonal metastable t′-(Ce_0.5Zr_0.5)O₂ and t′_meta-(Ce_0.5Zr_0.5)O₂ phases possessing random arrangement of the cations. The κ disk was prepared by reoxidizing a pyrochlore-type precursor in O₂ gas at 873 K. The σ_t as measured for the κ-CeZrO₄ was reproducible as a function of temperatures between 957 and 1190 K. At increasing temperatures above 1233 K, the σ_t decreased gradually with time due to the phase transition: κ→t′, and became consistent with the t′. Although the κ-CeZrO₄ phase is thermodynamically less stable than the t′-(Ce_0.5Zr_0.5)O₂, it was virtually stable up to around 1233 K. It was found from the change in the σ_t due to the phase transition that the σ_t for the metastable κ-CeZrO₄ was an order of magnitude higher than that for the t′ and was similar to that for the t′_meta. It was previously reported that a phase transition, t′_meta→t′, occurred above 1143 K. The phase transition, κ→t′, accompanied by redistribution of the cations appeared to occur at higher temperatures than that for t′_meta→t′ leaving random cation arrangement.