Involvement of brain oxidation in the cognitive impairment in a triple transgenic mouse model of Alzheimer's disease: noninvasive measurement of the brain redox state by magnetic resonance imaging.

Oxidative stress is considered to be related to the onset and/or progression of Alzheimer's disease (AD), but there is insufficient evidence of its role(s). In this study, we evaluated the relationships between the brain redox state and cognitive function using a triple transgenic mouse model of AD (3 × Tg-AD mouse). One group of 3 × Tg-AD mice started to receive an α-tocopherol-supplemented diet at 2 months of age and another group of 3 × Tg-AD mice was fed a normal diet. The levels of α-tocopherol, reduced glutathione, oxidized glutathione, and lipid peroxidation were decreased in the cerebral cortex and hippocampus at 4 months of age in the 3 × Tg-AD mice fed a normal diet. These reductions were abrogated by the supplementation of α-tocopherol in the diet. During Morris water maze testing, the 3 × Tg-AD mice did not exhibit cognitive impairment at 4 months of age, but started to show cognitive dysfunction at 6 months of age, and α-tocopherol supplementation suppressed this dysfunction. Magnetic resonance imaging (MRI) using 3-hydroxymethyl-proxyl as a probe showed decreases in the signal intensity in the brains of 3 × Tg-AD mice at 4 months of age, and this reduction was clearly attenuated by α-tocopherol supplementation. Taken together, these findings suggest that oxidative stress can be associated with the cognitive impairment in 3 × Tg-AD mice. Furthermore, MRI might be a powerful tool to noninvasively evaluate the increases in reactive radicals, especially those occurring during the early stages of AD.

Environmental risk assessment of genetically engineered herbicide-tolerant Zoysia japonica.

Herbicide-tolerant Zoysia grass (Zoysia japonica Steud.) has been generated previously through Agrobacterium tumefaciens-mediated transformation. The genetically modified (GM) Zoysia grass survived Basta spraying and grew to maturity normally while the wild-type (WT) grass stopped growing and died. GM Zoysia grass will permit more efficient weed control for various turf grass plantings such as home lawns, golf courses, and parks. We examined the environmental/biodiversity risks of herbicide-tolerant GM Zoysia before applying to regulatory agencies for approval for commercial release. The GM and WT Zoysia grass' substantial trait equivalence, ability to cross-pollinate, and gene flow in confined and unconfined test fields were selectively analyzed for environmental/biodiversity effects. No difference between GM and WT Zoysia grass in substantial traits was found. To assess the potential for cross-pollination and gene flow, a non-selective herbicide, Basta, was used. Results showed that unintended cross-pollination with and gene flow from GM Zoysia grass were not detected in neighboring weed species examined, but were observed in WT Zoysia grass (on average, 6% at proximity, 1.2% at a distance of 0.5 m and 0.12% at a radius of 3 m, and 0% at distances over 3 m). On the basis of these initial studies, we conclude that the GM Zoysia grass generated in our laboratory and tested in the Nam Jeju County field does not appear to pose a significant risk when cultivated outside of test fields.

Liver abscess after transcatheter oily chemoembolization for hepatic tumors: incidence, predisposing factors, and clinical outcome.

PURPOSE: To evaluate the incidence of, predisposing factors for, and clinical outcome of liver abscess developing in patients with hepatic tumors after transcatheter oily chemoembolization (TOCE). MATERIALS AND METHODS: During the past 6-year period, 2,439 patients with hepatic tumors underwent a total of 6,255 TOCE procedures. With a retrospective review of medical records, the authors evaluated the occurrence of liver abscess, the statistical significance of potential predisposing factors including portal vein obstruction, metastatic tumors, biliary abnormalities (type 1, simple biliary obstruction; type 2, status prone to ascending biliary infection), malignant gastrointestinal mucosal lesions, and additional gelatin sponge particle embolization in liver abscess formation, and the clinical outcome of abscess. RESULTS: Fifteen liver abscesses occurred in 14 patients (0.2%). Liver abscesses developed in three of 987 (0.3%) TOCE procedures for portal vein obstruction, three of 114 (2.6%) procedures for metastatic tumors, one of 49 (1.8%) for type 1 biliary abnormality, four of 55 (7.4%) for type 2 biliary abnormality, two of 18 (11.1%) for malignant gastrointestinal mucosal lesion, and nine of 2,108 (0.4%) for additional gelatin sponge particle embolization. Univariate and multivariate statistical analysis showed that type 2 biliary abnormality was a significant predisposing factor. The mortality related to liver abscess occurred in two patients (13.3%). Thirteen liver abscesses were successfully treated with parenteral antibiotics and percutaneous catheter drainage. However, irreversible deterioration of liver function occurred in two patients. Two of nine further TOCE procedures in three patients caused recurrent septicemia and liver abscess. CONCLUSION: The biliary abnormality prone to ascending biliary infection was the most important predisposing factor to the development of liver abscess after TOCE. Postembolic liver abscess could be effectively managed with percutaneous catheter drainage.

Structure of apo-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor.

d-Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) shows cooperative properties for binding coenzymes. The structure of apo-GAPDH from Palinurus versicolor has been solved at 2.0 A resolution by X-ray crystallography. The final model gives a crystallographic R factor of 0.178 in the resolution range 8 to 2 A. The structural comparison with holo-GAPDH from the same species reveals a conformational change induced by coenzyme binding similar to that observed in Bacillus stearothermophilus GAPDH but to a lesser extent. The differences in magnitude during the apo-holo transition between these two enzymes were analyzed with respect to the change of the amino acid composition in the coenzyme binding pocket. In the crystalline state of apo-GAPDH, the overall structures of the subunits are similar to each other; however, significant differences in temperature factors and minor differences in domain rotation upon coenzyme binding were observed for different subunits. These structural features are discussed in relation to the environmental asymmetry of crystallographically independent subunits.

Structure of active site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor.

The structure of active site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor was determined in the presence of coenzyme NAD+ at 1.88 A resolution with a final R-factor of 0.175. The structure refinement was carried out on the basis of the structure of holo-GAPDH at 2.0 A resolution using the program XPLOR. The carboxymethyl group connected to Cys149 is stabilized by a hydrogen bond between its OZ1 and Cys149N, and charge interaction between the carboxyl group and the nicotinamide moiety. The modification of Cys149 induced conformational changes in the active site, in particular, the site of sulphate ion 501 (the proposed attacking inorganic phosphate ion in catalysis), and segment 208-218 nearby. Extensive hydrogen-bonding interactions occur in the active site, which contribute to the higher stability of the modified enzyme. The modification of the active site did not affect the conformation of GAPDH elsewhere, including the subunit interfaces. The structures of the green and red subunits in the asymmetric unit are nearly identical, suggesting that the half-site reactivity of this enzyme is from ligand-induced rather than pre-existing asymmetry. It is proposed that the carboxymethyl group takes the place of the acyl group of the reaction intermediate, and the catalytic mechanism of this enzyme is discussed in the light of a comparison of the structures of the native and the carboxymethylated GAPDH.

Structure of D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor carrying the fluorescent NAD derivatives at 2.7 A resolution.

Ultraviolet irradiation of carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase leads to the formation of a fluorescent NAD derivative. The structure of the enzyme from Palinurus versicolor carrying this derivative has been determined by molecular replacement and refined using the restrained least-squares method to 2.7 A with a final crystallographic R-factor of 0.205. The polypeptide chain folding and subunit arrangement closely resemble the known structure of Homarus americanus GAPDH. The structure at the modified active site confirms that the photochemical reaction is a half-of-the-sites reaction and occurs in the red and yellow subunit pair. The stereochemical relationship between the Trp residues at the active site shows that Trp 310 is most probably involved in a radiationless energy transfer to the fluorophore. A large solvent channel connecting the catalytic and NAD(+)-binding sites was found parallel to the crystallographic axis alpha from packing analysis, suggesting that this crystal form may be suitable for a kinetic crystallographic study of the apoenzyme.

Preliminary crystallographic studies of lobster D-glyceraldehyde-3-phosphate dehydrogenase and the modified enzyme carrying the fluorescent derivative.

When the active-site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase is irradiated with ultraviolet light in the presence of NAD+, a fluorescent NAD derivative that is covalently linked to the enzyme is obtained. A preliminary crystallographic study of this fluorescent derivative, as well as of the native and the carboxymethylated enzymes from Palinurus versicolor, showed that they are isomorphous and belong to space group C2 as reported for the native enzyme from Palinurus vulgaris. The three forms of the enzyme, although they have identical unit cell parameters, differ considerably in their diffraction patterns, indicating marked differences in conformation in spite of the fact that they differ chemically only in a restricted region around the active site.