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排序方式: 共有297条查询结果,搜索用时 406 毫秒
91.
Irinotecan or 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) is an anticancer pro-drug used in the treatment of many types of cancer. We describe here the validation of an analytical method for CPT-11 and its metabolites, including an active metabolite, 7-ethyl-10-hydroxycamptothecin (SN-38), its glucuronidated form, SN-38G, and several cytochrome P450 3A-mediated products such as 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecin (APC) using a high-performance liquid chromatography connected to parallel fluorescence and mass spectrometry detection systems. This method is characterized as follows: (1) simple extraction of the analytes from biomaterials with perchloric acid/methanol; (2) sensitive quantitation of major metabolites (SN-38G, SN-38 and APC) with a fluorescence detector (FLD), where the limits of quantitation by FLD were 2.5 ng/mL for SN-38G and APC, 5 ng/mL for CPT-11 and 1 ng/mL for SN-38, respectively; (3) parallel selective monitoring of the metabolites including minor metabolites with a mass selected detector (MSD). There was no observed interference by other drugs expected to be co-administered. This method showed its usefulness by identifying a novel metabolite produced in human hepatic microsomes. The results indicate that this combination of FLD and MSD enables a highly selective analysis of CPT-11 and its metabolites, and is useful for studies both in vivo and in vitro. 相似文献
92.
Yoshihiro Ushigoe Shogo Tanaka Masatomo Nojima Kevin J. McCullough 《Tetrahedron letters》1994,35(52):9741-9744
-Hydroperoxyisochroman derivatives 5 react with formaldehyde under acidic conditions to produce mixtures of bicyclic 1,2,4,6-tetroxepane 9 and 1,2,4,6,8-pentoxonane 10 derivatives. The structure of the compound 10a was unambiguously established by the X-ray analysis. With acetaldehyde, only the corresponding 1,2,4,6-tetroxepanes 9 were obtained. 相似文献
93.
Qi Xue Bryan Kit Yue Ng Ho Wing Man Tai-Sing Wu Yun-Liang Soo Molly Mengjung Li Shogo Kawaguchi Kwok Yin Wong Shik Chi Edman Tsang Bolong Huang Tsz Woon Benedict Lo 《Chemical science》2021,13(1):50
Precisely tuning the nuclearity of supported metal nanoclusters is pivotal for designing more superior catalytic systems, but it remains practically challenging. By utilising the chemical and molecular specificity of UiO-66-NH2 (a Zr-based metal–organic framework), we report the controlled synthesis of supported bi- and trinuclear Cu-oxo nanoclusters on the Zr6O4 nodal centres of UiO-66-NH2. We revealed the interplay between the surface structures of the active sites, adsorption configurations, catalytic reactivities and associated reaction energetics of structurally related Cu-based ‘single atoms’ and bi- and trinuclear species over our model photocatalytic formic acid reforming reaction. This work will offer practical insight that fills the critical knowledge gap in the design and engineering of new-generation atomic and nanocluster catalysts. The precise control of the structure and surface sensitivities is important as it can effectively lead to more reactive and selective catalytic systems. The supported bi- and trinuclear Cu-oxo nanoclusters exhibit notably different catalytic properties compared with the mononuclear ‘Cu1’ analogue, which provides critical insight for the engineering of more superior catalytic systems.The controlled synthesis of novel bi- and trinuclear Cu-oxo nanoclusters supported on UiO-66-NH2 that show notably different catalytic properties in the photocatalytic formic acid decomposition reaction is reported. 相似文献
94.
Keisuke Fukumura Yuki Narimatsu Shogo Moriwaki Eiko Iwakoshi-Ukena Megumi Furumitsu Kazuyoshi Ukena 《Molecules (Basel, Switzerland)》2021,26(19)
We previously identified a novel small hypothalamic protein, neurosecretory protein GL (NPGL), which induces feeding behavior and fat accumulation in rodents depending on their diet. In the present study, we explored the effects of NPGL on feeding behavior and energy metabolism in mice placed on a long-term high-fat diet with 60% calories from fat (HFD 60). Overexpression of the NPGL precursor gene (Npgl) over 18 weeks increased food intake and weight. The weekly weight gain of Npgl-overexpressing mice was higher than that of controls until 7 weeks from induction of overexpression, after which it ceased to be so. Oral glucose tolerance tests showed that Npgl overexpression maintained glucose tolerance and increased blood insulin levels, and intraperitoneal insulin tolerance tests showed that it maintained insulin sensitivity. At the experimental endpoint, Npgl overexpression was associated with increased mass of the perirenal white adipose tissue (WAT) and decreased mass of the epididymal WAT (eWAT), resulting in little effect on the total WAT mass. These results suggest that under long-term HFD 60 feeding, Npgl overexpression may play a role in avoiding metabolic disturbance both by accelerating energy storage and by suppressing excess fat accumulation in certain tissues, such as the eWAT. 相似文献
95.
Shogo Kuriyama Shenglan Wei Takeru Kato Yoshiaki Nishibayashi 《Molecules (Basel, Switzerland)》2022,27(7)
A series of manganese complexes bearing an anionic pyrrole-based PNP-type pincer ligand and an anionic benzene-based PCP-type pincer ligand is synthesized and characterized. The reactivity of these complexes toward ammonia formation and silylamine formation from dinitrogen under mild conditions is evaluated to produce only stoichiometric amounts of ammonia and silylamine, probably because the manganese pincer complexes are unstable under reducing conditions. 相似文献
96.
97.
98.
The atom-probe field-ion microscope (atom-probe FIM) was applied for the first time to GaAs and GaP which belong to the III–V compound semiconductors. The general character of the pulsed field-evaporation of GaAs and GaP was quite similar. Ga field-evaporated predominantly in the form of singly charged ions. As and P also field-evaporated mainly as singly charged ions, but their abundances were small compared with Ga+. It appears that As (or P) atoms can field-evaporate more easily in the form of AsO+ (or PO+) in the presence of oxygen on the surface. In all experiments, GaAsn+ and GaPn+ were rarely detected. After chemical etching the surfaces were covered with oxide films and various oxide ions were detected. The abundance of oxide ions dramatically decreased after field evaporation in hydrogen. No distinct difference between the 〈111〉 orientations of these materials which have zinc-blende structure could be observed. Most of the experimental results obtained were explained in terms of the existing theory of field evaporation. It was concluded that field penetration effects have a considerable influence on the field evaporation processes of these materials as well as on the field ionization processes. 相似文献
99.
100.
Daisuke Tanaka Satoru Yoneda Yoko Yamashiro Akihiro Sakatoku Takuro Kayashima Kasumi Yamakawa Shogo Nakamura 《Applied biochemistry and biotechnology》2012,168(2):327-338
A psychrotrophic Pseudomonas sp. TK-3 was isolated from dirty and cool stream water in Toyama, Japan from which we cloned and characterized the bacterial lipase LipTK-3. The sequenced DNA fragment contains an open reading frame of 1,428?bp that encoded a protein of 476 amino acids with an estimated molecular mass of 50,132?Da. The lipase showed high sequence similarity to those of subfamily ??.3 lipase and had a conserved GXSXG motif around the catalytic Ser residue. Its optimal temperature was 20?C25?°C, lower than in most other subfamily ??.3 lipases. The lipase exhibited about 30?% of maximal activity at 5?°C. The optimal pH value was 8.0. The activity was strongly inhibited by EDTA and was highly dependent on Ca2+. Tricaprylin and p-nitrophenyl caprylate were the most favorable substrates among the triglycerides and p-nitrophenyl esters, respectively. LipTK-3 also showed high activity towards natural substrates including edible vegetable oils and animal fats. Furthermore, LipTK-3 was very active and stable in the presence of several detergents, metal ions, and organic solvents. This cold-adapted lipase may prove useful for future applications. 相似文献