The Effect of Antiozonants on the Reaction of Dyes with Ozone. 2 — Contribution of Antiozonant to the Performance of a ZnO-Rose Bengal Photosensor During Electrophotography

The breakdown of zinc oxide-Rose Bengal photosensor has been found to be caused by the fading of Rose Bengal and degradation of resin by ozone and singlet oxygen. When 4, 4′-methyiene-bis(2, 6-di-t-butyiphenol), an antiozonant, was added the life of the photosensor was extended from 500 to 2000 charge-light-decay cycles.     

Beneficial effects of the combination of idebenone and manidipine 2HCl on neurological deficits and histological changes following cerebrovascular lesions in stroke-prone spontaneously hypertensive rats

We investigated the effects of the combination of idebenone, an energy metabolism enhancer, and manidipine 2HCl, a dihydropyridine-derivative calcium antagonist, on neurological deficits and histological changes in the brain and kidneys of stroke-prone spontaneously hypertensive rats (SHRSP) with cerebrovascular lesions (stroke). The SHRSP were kept on a 1% NaCl solution as their drinking water to synchronize the onset of stroke. After the onset of stroke symptoms, the salt solution was replaced with tap water. On the day following the onset of stroke, idebenone (50 mg/kg), manidipine 2HCl (2 mg/kg) or a combination of idebenone (50 mg/kg) and manidipine 2HCl (2 mg/kg) was administered orally once a day for 3 weeks. In the combination group and manidipine 2HCl-treated group, the neurological deficits after the onset of stroke were ameliorated during the entire experimentalperiod. Especially, the combination significantly decreased the number of days with severe neurological deficits as compared to the control group. The combination and manidipine 2HCl significantly recovered the decrease in body weight and ameliorated the increase of brain weight, which was mainly caused by edema, significantly as compared to the control group. Manidipine 2HCl ameliorated the histological changes in the brain. In the combination group, the histological changes in both the brain and the kidneys were ameliorated. In conclusion, the combination of idebenone and manidipine 2HCl significantly ameliorated the neurological deficits and the histological changes in the brain and the kidney of SHRSP with stroke as compared to each individual treatment. We concluded that manidipine 2HCl enhances the therapeutic effect of idebenone in the treatment of cerebrovascular diseases.     

Membrane interaction of synthetic peptides related to the putative fusogenic region of PH-30 alpha, a protein in sperm-egg fusion

In order to investigate the relationship between structure and function of a putative fusogenic region of PH-30a, a protein active in sperm-egg fusion, two peptides, SFP22 and SFP23, whose sequences correspond to the residues 90-111 and 89-111 of PH-30 alpha, respectively, were chemically synthesized. An analog of SFP23, SFP23AA, which has an Ala-Ala sequence instead of the Pro-Pro sequence in SFP23, was also prepared. The CD study indicated that SFP22 and SFP23 mainly took a beta-structure in the presence of DPPC and DPPC/DPPG (3/1) vesicles, while SFP23AA showed an alpha-helical pattern though the alpha-helical content calculated was low (25-30%). alpha-Helical CD curve was observed for these peptides in trifluoroethanol. The membrane-perturbing activity of SFP22 and SFP23 was weaker than that of SFP23AA. On the other hand, the membrane-fusogenic activity of SFP22 and SFP23 to acidic phospholipid bilayers was much stronger than that of SFP23AA. All the peptides caused very weak cell lysis. These results are consistent with the reported speculation [Blobel, C. P. et al. (1992), Nature (London) 356, 248-252] that residues 90-111 of PH-30 alpha may be the fusogenic region and suggest that the Pro-Pro sequence is one of the important factors for holding the active secondary structure of the fusogenic region of PH-30 alpha in membranes.     

Enhancement of nucleoside phosphorylation activity in an acid phosphatase

Escherichia blattae non-specific acid phosphatase (EB-NSAP)possesses a pyrophosphate-nucleoside phosphotransferase activity,which is C-5'-position selective. Current mutational and structuraldata were used to generate a mutant EB-NSAP for a potentialindustrial application as an effective and economical proteincatalyst in synthesizing nucleotides from nucleosides. First,Gly74 and Ile153 were replaced by Asp and Thr, respectively,since the corresponding replacements in the homologous enzymefrom Morganella morganii reduced the K_m value for inosine andthus increased the productivity of 5'-IMP. We determined thecrystal structure of G74D/I153T, which has a reduced K_m valuefor inosine, as expected. The tertiary structure of G74D/I153Twas virtually identical to that of the wild-type. In addition,neither of the introduced side chains of Asp74 and Thr153 isdirectly involved in the interaction with inosine in a hypotheticalbinding mode of inosine to EB-NSAP, although both residues aresituated near a potential inosine-binding site. These findingssuggested that a slight structural change caused by an aminoacid replacement around the potential inosine-binding site couldsignificantly reduce the K_m value. Prompted by this hypothesis,we designed several mutations and introduced them to G74D/I153T,to decrease the K_m value further. This strategy produced a S72F/G74D/I153Tmutant with a 5.4-fold lower K_m value and a 2.7-fold higherV_max value as compared to the wild-type EB-NSAP.     

Estimation of daily intake of PCDDs, PCDFs and Co-PCBs from baby foods

A study of the dietary intake of dioxins, consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) through baby foods in the metropolitan Tokyo area was carried out. The samples were homemade baby foods prepared by the total diet-market basket method and baby foods (mainly commercial items) prepared by the duplicate portion method. The daily intake of dioxins per kg of body weight from baby foods in each weaning stage for the case of half intake of homemade baby foods and the other half of mainly commercial items was 0.32 pg TEQ/kg/day in the early stage, 0.45 pg TEQ/kg/day in the intermediate stage, 0.58 pg TEQ/kg/day in the late stage and 1.25 pg TEQ/kg/day in the completed stage. While the daily intakes increase with the weaning progress, they were less than the tolerable daily intake (TDI) of 4 pg TEQ/kg/day for dioxins established in Japan. Dioxins were mainly taken through formula milk in early stage of weaning period, but then were taken through protein-based foods in the subsequent weaning stage.