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排序方式: 共有223条查询结果,搜索用时 172 毫秒
1.
Enantiomeric Cyclic Peptides with Different Caco‐2 Permeability Suggest Carrier‐Mediated Transport 下载免费PDF全文
B. Sc. Eduard Puig Prof. Dr. Beat Ernst Prof. Dr. Horst Kessler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8023-8027
Recently, oral absorption of cyclic hexapeptides was improved by N‐methylation of their backbone amides. However, the number and position of N‐methylations or of solvent exposed NHs did not correlate to intestinal permeability, measured in a Caco‐2 model. In this study, we investigate enantiomeric pairs of three polar and two lipophilic peptides to demonstrate the participation of carrier‐mediated transporters. As expected, all the enantiomeric peptides exhibited identical lipophilicity (logD7.4) and passive transcellular permeability determined by the parallel artificial membrane permeability assay (PAMPA). However, the enantiomeric polar peptides exhibited different Caco‐2 permeability (Papp) in both directions a–b and b–a. The same trend was observed for one of the lipophilic peptide, whereas the second lipophilic enantiomer pair showed identical Caco‐2 permeability (within the errors). These findings provide the first evidence for the involvement of carrier‐mediated transport for peptides, especially for those of polar nature. 相似文献
2.
Hejia Hu Linlin Wu Mei Li Cun Xue Guangcheng Wang Siying Chen Yong Huang Lin Zheng Aimin Wang Yueting Li Zipeng Gong 《Biomedical chromatography : BMC》2020,34(1):e4714
Eucommia ulmoides Oliv. (E. ulmoides) is a valuable and nourishing medicinal herb in China that has been used in the treatment of hypertension. Given the fact that most traditional Chinese medicine is mainly used to treat disease, investigating the pharmacokinetics of traditional Chinese medicines in the pathological state is more useful than that in the normal state. However, the differences in the absorption kinetics of active ingredients of E. ulmoides extract between pathological and physiological conditions have not been reported. Therefore, in this study, the rat intestinal in situ circulatory perfusion model was used to investigate the differences in absorption kinetics of seven active ingredients of E. ulmoides extract in normal and spontaneously hypertensive rats, namely, genipinic acid, protocatechuic acid, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, (+)-pinoresinol di-O-β-D -glucopyranoside and (+)-pinoresinol 4′-O-β-D -glucopyranoside. Our results indicate that the pathological state of spontaneous hypertension may change the absorption of active components of E. ulmoides extracts, and these findings may provide a reference for improving the rational use of E. ulmoides in the clinic. 相似文献
3.
采用示波极谱法对183名反复上呼吸道感染患儿及118名健康体检儿同时进行发样锌,铁,铜测定,结果表明,反复上呼吸道感染儿发锌,铁均低于健康体检儿,有高度显著性差异,铜只在婴儿组反复感儿高于健康体检儿,其它各年龄组反复上感儿低于健康栓检儿或无显著性差异,说明以2儿童进行常规发样微量元素普查,发现低锌,低铁者及时给予补充,可减少感染性疾病的发生率。铜与免疫功能的关系尚待研究。 相似文献
4.
Functional-based screening of crude β-galactosidase activities from 42 yeast strains resulted in the selection of a single
enzyme of potential interest as a digestive supplement. β-Galactosidase produced by Kluyveromyces marxianus DSM5418 was purified to homogeneity by a combination of gel filtration, ion-exchange, and hydroxylapatite chromatographies.
The denatured (123 kDa) and native molecular masses (251 kDa) suggest that the enzyme is a homodimer. The optimum pH and temperature
of the purified enzyme were 6.8 and 37°C, respectively. The unpurified β-galactosidase in particular displayed a high level
of stability when exposed to simulated intestinal conditions in vitro for 4 h. Matrix-assisted laser desorption ionization
mass sectrometry analysis revealed that the enzyme's trypsin-generated peptide mass fingerprint shares several peptide fragment
hits with β-galactosidases from Kluyveromyces lactis. This confirms the enzyme's identity and indicates that significant sequence homology exists between these enzymes. 相似文献
5.
6.
微量元素锌与反复呼吸道感染的相关性 总被引:2,自引:1,他引:2
陈洁 《广东微量元素科学》1996,3(1):22-23
对28例反复呼吸道感染患儿(下称复感儿)及26例健康儿进行微量元素发锌测定。发现前者发锌平均值为(92.3±14.7)×10~(-6),后者为(132.5±21.5)×10~(-6),P<0.01,差异非常显著。对复感儿进行口服锌治疗,观察其疗效及治疗前后发锌变化。治疗前发锌平均值为(92.3±14.7)×10~(-6),治疗后为(137.5±20.2)×10~(-6),P<0.01差异非常显著。有效率达85.7%。故缺锌可能是复感儿患病的影响因素之一,锌治疗小儿反复呼吸道感染是十分必要的。 相似文献
7.
Scientific evidence in the prevention and treatment of various disorders is accumulating regarding probiotics. The health
benefits supported by adequate clinical data include increased resistance to infectious disease, decreased duration of diarrhea,
management of inflammatory bowel disease, reduction of serum cholesterol, prevention of allergy, modulation of cytokine gene
expression, and suppression of carcinogen production. Recent ventures in metabolic engineering and heterologous protein expression
have enhanced the enzymatic and immunomodulatory effects of probiotics and, with time, may allow more active intervention
among critical care patients. In addition, a number of approaches are currently being explored, including the physical and
chemical protection of cells, to increase probiotic viability and its health benefits. Traditional immobilization of probiotics
in gel matrices, most notably calcium alginate and κ-carrageenan, has frequently been employed, with noted improvements in
viability during freezing and storage. Conflicting reports exist, however, on the protection offered by immobilization from
harsh physiologic environments. An alternative approach, microencapsulation in “artificial cells,” builds on immobilization
technologies by combining enhanced mechanical stability of the capsule membrane with improved mass transport, increased cell
loading, and greater control of parameters. This review summarizes the current clinical status of probiotics, examines the
promises and challenges of current immobilization technologies, and presents the concept of artificial cells for effective
delivery of therapeutic bacterial cells. 相似文献
8.
9.
LC–MS/MS determination and interaction of the main components from the traditional Chinese drug pair Danshen–Sanqi based on rat intestinal absorption 下载免费PDF全文
Juan Huang Jing Zhang Junqi Bai Wen Xu Dinghong Wu Xiaohui Qiu 《Biomedical chromatography : BMC》2016,30(12):1928-1934
The Chinese drug pair Danshen (Salvia miltiorrhiza)–Sanqi (Panax ginseng) has been widely used for centuries treating various cardiovascular disorders, among which salvianlic acid B (SAB), ginsenoside Rg1 (GRg1), ginsenoside Rb1 (GRb1) and notoginsenoside R1 (NGR1) were identified as the major components. The present study focused on the interaction between these components based on investigating their intestinal absorption using the Ussing chamber technique. The concentrations of SAB, GRg1, GRb1 and NGR1 in the intestinal perfusate were determined by LC–MS/MS method, followed by Q (accumulative quantity) and Papp (apparent permeability). The results showed that all these four main components displayed very low permeabilities, which implied their poor absorption in the rat intestine. The intestinal absorption level of SAB displayed regioselectivity: duodenum < jejunum < ileum. However, there was no significant difference in the absorption of GRg1 and GRb1 in the different segments. The Q and Papp values of the four main components were obviously increased in jejunum when co‐administrating Danshen extract with Sanqi extract. In conclusion, compatibility of Danshen and Sanqi could remarkably improve the intestinal absorption level of the main components in the pair. To some extent, this might explain the nature of the compatibility mechanisms of composite formulae in TCMs. 相似文献
10.
Biotransformation and metabolic profile of Xian‐Ling‐Gu‐Bao capsule,a traditional Chinese medicine prescription,with rat intestinal microflora by ultra‐performance liquid chromatography coupled with quadrupole time‐of‐flight tandem mass spectrometry analysis 下载免费PDF全文
《Biomedical chromatography : BMC》2018,32(4)