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51.
Kazuhisa Maeda Yasushi Tomita Masako Naganuma Hachiro Tagaml 《Photochemistry and photobiology》1996,64(1):220-223
Guinea pig skin becomes more pigmented following exposure to UV rays. This melanization was accompanied by enhanced intensity of tyrosinase-staining and increased number of tyrosinase-positive melanocytes (MELty+), with resultant enhancement of melanin synthesis. To clarify the regulatory mechanism for melanization following UV irradiation, organ-cultured guinea pig skins have been used to examine their melanogenic responses to exogenous stimulation. This organ culture system responded well to UV irradiation, by increasing melanogenic activity. Also, in this system, phospholipases (PL), arachidonic acid, interleukin-1α and melanocytestimulating hormone, but not endothelin-1 or phosphatidylinositol-specific PLC (PI-PLC), stimulated melanogenesis to various extents as indicated by the number of MELty+ and morphological changes. Among them, the PLA2 and PLD were found to have a potent stimulatory property for melanocytes. They might affect melanocytes directly or indirectly through an effect on keratinocytes. These results suggest that PLA2 and PLD play a key role in epidermal hyperpigmentation after UV irradiation or inflammation. 相似文献
52.
Soh N Imato T Kawamura K Maeda M Katayama Y 《Chemical communications (Cambridge, England)》2002,(22):2650-2651
A novel fluorescent probe, which could be the first example of a ratiometric molecular probe for direct monitoring of NO production, has been developed using a 'spin-exchange' mechanism. 相似文献
53.
1,3-Dipyrrolyl-1,3-propanediones, synthesized from pyrroles and malonyl chloride, form BF2 complexes, which represent a new class of naked-eye sensors for halide and oxoanions. The association mode for the interactions of both the pyrrolyl NH and bridging CH protons with anions was confirmed by 1H NMR chemical shifts in CD2Cl2 and supported by theoretical studies. The binding constants (Ka) were estimated as 8.1x10(4), 2.0x10(3), 3.3x10(2), 1.3x10(4), and 80 M(-1) for F-, Cl-, Br-, H2PO4(-), and HSO4(-) by UV/Vis absorption spectral changes in CH2Cl2. Augmentation of Ka compared with dipyrrolylquinoxaline for H2PO4(-) is much larger than those for other anions. Contrary to other anions, F- quenches the emission almost completely, which was detected by the fluorescence spectrum as well as the naked-eye. In the case of the chloride anion complex, the formation of Cl(-)-bridged 1D networks, in which anion is associated with two BF2 complexes, is observed in the solid state. 相似文献
54.
Hayami S Hashiguchi K Juhász G Ohba M Okawa H Maeda Y Kato K Osaka K Takata M Inoue K 《Inorganic chemistry》2004,43(14):4124-4126
Cobalt(II) compounds [Co(pyterpy)Cl(2)].MeOH (1.(MeOH)) and [Co(pyterpy)Cl(2)].2H(2)O (1.(2H(2)O)) were synthesized. The compound 1.(MeOH) forms the quasi 3-D networks by making pi-pi stacking between the 1-D chains. The methanol molecules from 1.(MeOH) can be removed by heating, and substituted by absorption of water molecules. The MeOH molecules in 1.(MeOH) are removed by heating at 410 K, and they are substituted by water molecules to form 1.(2H(2)O). 1.(2H(2)O) exhibits a S = (3)/(2) (HS) left arrow over right arrow S = (1)/(2) (LS) spin transition with a thermal hysteresis. We have succeeded in constructing a guest dependent 1-D spin-crossover cobalt(II) compound. 相似文献
55.
Ohno H Wakayama R Maeda S Iwasaki H Okumura M Iwata C Mikamiyama H Tanaka T 《The Journal of organic chemistry》2003,68(15):5909-5916
Alkyl radicals generated by treatment of thiocarbamates of conformationally favorable 3-alkyl-3-arylpropan-1-ols with tris(trimethylsilyl)silane and AIBN efficiently undergo intramolecular ipso substitution of the methoxy group, yielding the corresponding cyclized products. In contrast, either conformationally favorable or flexible 1-arylalkan-3- or 4-ones easily cyclize into five- or six-membered condensed rings by treatment with SmI(2) via ketyl radical intermediates. The addition of HMPA as cosolvent dramatically changes the cyclization mode of the SmI(2)-induced reaction, and the para-cyclization products are exclusively formed. This "HMPA effect" can be rationalized by the strong chelating ability of HMPA with the samarium atom. 相似文献
56.
57.
J Gon T Nakagawa H Maeda K Nakamura H Sakuma T Tashiro Y Matsuoka N Yamaguchi 《Radioisotopes》1988,37(1):7-14
Dynamic hepatobiliary image data were analyzed by the mathematical deconvolution to derive the transfer function (TF) which represents the impulse response function of the liver following direct bolus injection of a tracer into the liver. Biliary flow was evaluated by TF in patients with previous hepatobiliary surgery to detect abnormal flow causing problems such as cholangitis. Serial image data were collected for 60 min after intravenous injection of 37-75 MBq (1-2 mCi) of 99mTc-N-pyridoxyl-5-methyltryptophan (99mTc-PMT). TF was obtained by the matrix algorithm, using regional hepatogram as output and time-activity curve over the heart as input function. Minimum, mean and maximum transit time (Max. TT) were determined from TF. The functional image for each of the transit times was constructed by displaying the distribution of the values for matrix elements with a color scale. In this study, a critical Max. TT of 60 min was used to detect abnormal biliary flow. Of 30 cases, 9 positive cases were discriminated from 21 negative cases on the basis of the finding of presence or absence of areas with Max. TT of more than 60 min anywhere in the liver. Bowel activity overlapping the liver was excluded in the judgment. The validity of this method was evaluated in comparison with the clinical courses after surgery with (8 cases) or without (22 cases) problems. The results were sensitivity of 88%, specificity of 91%, accuracy of 90% and positive predictive value of 78%.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
58.
Kondo M Miyazawa M Irie Y Shinagawa R Horiba T Nakamura A Naito T Maeda K Utsuno S Uchida F 《Chemical communications (Cambridge, England)》2002,(18):2156-2157
A coordination polymer [Zn(pyta)(OH)] (pyta = 4-pyridylthioacetate), was synthesized and structurally characterized; it is constructed by an alternating assembly of two types of homo-chiral helices, [Zn-OH] and [Zn-pyta], in which the sulfide moieties are fastened in the latter columns. 相似文献
59.
A high-powered, microwave-induced nitrogen–oxygen plasma (N2–O2–MIP) generated by using an Okamoto cavity at atmospheric pressure was investigated when the observation height, the flow rate of carrier gas, and the oxygen content were varied as the experimental parameters. The emission characteristics of the plasma were evaluated with regard to the excitation temperature and the intensity ratio of atomic line to ionic line. The excitation temperature of the N2–O2–MIP was in the range of 5100–5700 K when the oxygen content was varied from 0 to 30% at the observation height of 7 mm and the carrier gas flow rate of 0.6 l/min. The intensity ratio of atomic line to ionic line was elevated with an increase in the oxygen content. 相似文献
60.
Diacyl peroxides reacted at room tempt with cytidine and adenosine. The former gave 4-acyl and 3-oxido derivatives and the latter gave 6-acyl and 1-oxido derivatives. At 90°, diacetyl peroxide reacted with guanosine, adenosine, cytidine, and uridine by a homolytic process to give their C-methylated derivatives. The latter reaction was accelerated by the presence of a ferrous ion. 相似文献