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81.
Kawakami T Nagata T Muraguchi A Nishimura T 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,787(1):223-229
Apoptosis is an essential process for selection of T lymphocytes specific for foreign antigen in the process of mammalian thymus maturation. Proteomics, a comprehensive study of proteins expressed in a cell, will facilitate the systematic analysis of protein molecules related to such a complicated biological system. Protein expression profiles including information about protein signatures, localization and their quantitative changes with extracellular stimulations are extremely useful to construct intracellular pathway models resulting in the apoptotic cell death. 相似文献
82.
We designed a novel type of cationic lipid, lipids with a cationic polar group in the polyamidoamine dendron, because these dendron-bearing lipids are expected to form complexes with plasmid DNA and achieve efficient transfection of cells by synergy of endosome buffering and membrane fusion with the endosome, both of which are useful for the promotion of the transfer of plasmid DNA from endosome to cytosol. Four kinds of lipids with polyamidoamine dendrons of first to fourth generations, DL-G1, DL-G2, DL-G3, and DL-G4, were synthesized. The lipid with a dendron of a higher generation exhibited greater ability to form lipoplexes with plasmid DNA, as estimated by agarose gel electrophoresis. While the DL-G1 lipoplex did not transfect CV1 cells, the lipoplexes containing the DL-G2, DL-G3, or DL-G4 could induce transfection of the cells, and their activity was elevated with increasing generation of the dendron. Addition of dioleoylphosphatidylethanolamine (DOPE), which is known to increase fusion ability of a lipid membrane, into the lipoplexes greatly enhanced their transfection activity. In addition, the comparison with DC-Chol-containing lipoplex, which is widely used as a nonviral vector, showed that the DL-G3-DOPE lipoplex exhibits more efficient transfections. These findings imply that these dendron-bearing lipids may form the basis for a novel family of cationic lipids for efficient gene delivery. 相似文献
83.
Yamamoto Y Tsutsumi Y Yoshioka Y Nishibata T Kobayashi K Okamoto T Mukai Y Shimizu T Nakagawa S Nagata S Mayumi T 《Nature biotechnology》2003,21(5):546-552
Addition of polyethylene glycol to protein (PEGylation) to improve stability and other characteristics is mostly nonspecific and may occur at all lysine residues, some of which may be within or near an active site. Resultant PEGylated proteins are heterogeneous and can show markedly lower bioactivity. We attempted to develop a strategy for site-specific mono-PEGylation using tumor necrosis factor-alpha (TNF-alpha). We prepared phage libraries expressing TNF-alpha mutants in which all the lysine residues were replaced with other amino acids. A fully bioactive lysine-deficient mutant TNF-alpha (mTNF-alpha-Lys(-)) was isolated by panning against TNF-alpha-neutralizing antibody despite reports that some lysine residues were essential for its bioactivity. mTNF-alpha-Lys(-) was site-specifically mono-PEGylated at its N terminus. This mono-PEGylated mTNF-alpha-Lys(-), with superior molecular uniformity, showed higher bioactivity in vitro and greater antitumor therapeutic potency than randomly mono-PEGylated wild-type TNF-alpha. These results suggest the usefulness of the phage display system for creating functional mutant proteins and of our site-specific PEGylation approach. 相似文献
84.
Masahiko?HirataEmail author Mihoko?Nakagawa Harumi?Funakoshi Takuya?Iwamoto Waka?Otozu Daisuke?Kiyota Shirou?Kuroki Kiichi?Fukuyama 《Journal of Ethology》2003,21(2):161-168
Distance between dam and offspring (1–121 days old) in a herd of Japanese Black cattle (Bos taurus) grazing a tropical grass (Paspalum notatum) pasture (1.5 ha) was investigated during 7-h grazing periods over grazing seasons from May (spring) to October (autumn).
The mother–young distance was not constant throughout the grazing period, repeatedly increasing and decreasing. Although significant
periodicity was always detected in the mother–young distance, there was no consistent dominant cycle, indicating the complexity
of the within-day pattern of mother–young distance. The mean mother–young distance over the grazing period increased as a
calf aged, reaching a plateau at an age of about 33 days. The mean distance of a calf from its mother was usually shorter
than that from a non-mother cow, with the difference between the mean distances decreasing sharply until a calf became about
35 days old. The results and literature show that mutual independence of mother and young rapidly develops in the first 30–50 days
after parturition.
Electronic Publication 相似文献
85.
Temporally distinct requirements for endothelin receptor B in the generation and migration of gut neural crest stem cells 总被引:19,自引:0,他引:19
Loss of Endothelin-3/Endothelin receptor B (EDNRB) signaling leads to aganglionosis of the distal gut (Hirschsprung's disease), but it is unclear whether it is required primarily for neural crest progenitor maintenance or migration. Ednrb-deficient gut neural crest stem cells (NCSCs) were reduced to 40% of wild-type levels by embryonic day 12.5 (E12.5), but no further depletion of NCSCs was subsequently observed. Undifferentiated NCSCs persisted in the proximal guts of Ednrb-deficient rats throughout fetal and postnatal development but exhibited migration defects after E12.5 that prevented distal gut colonization. EDNRB signaling may be required to modulate the response of neural crest progenitors to migratory cues, such as glial cell line-derived neurotrophic factor (GDNF). This migratory defect could be bypassed by transplanting wild-type NCSCs directly into the aganglionic region of the Ednrb(sl/sl) gut, where they engrafted and formed neurons as efficiently as in the wild-type gut. 相似文献
86.
An asymmetric carbon-carbon bond-forming reaction at the 2-position of a piperidine skeleton was exploited. This method consisted of a reaction between 1-(4-methoxybenzoyl)-3,4-didehydro-2-methoxypiperidines and dimethyl malonate catalyzed by Cu(II)-chiral 2,2'-isopropylidenebis(4-phenyl-2-oxazoline) to afford a 2-substituted piperidine skeleton with moderate enantioselectivity. 相似文献
87.
Muto T Feese MD Shimada Y Kudou Y Okamoto T Ozawa T Tahara T Ohashi H Ogami K Kato T Miyazaki H Kuroki R 《The Journal of biological chemistry》2000,275(16):12090-12094
Thrombopoietin (TPO) is a cytokine that primarily stimulates megakaryocytopoiesis and thrombopoiesis. TPO has a unique C-terminal tail peptide of about 160 amino acids that consists mostly of hydrophilic residues and contains six N-linked sugar chains. In order to investigate the biological function of the C-terminal domain, two series of mutations were performed. One is systematic truncation from the C terminus. Another is elimination of N-glycosylation sites in the C-terminal domain by Asn to Gln mutations. After the mutant proteins were expressed by mammalian cells, it was found that the elimination of the N-linked sugar sites did not affect the biological activity, whereas truncation of the C-terminal domain resulted in elevation of in vitro activity up to 4-fold. The C-terminal peptide itself was found to inhibit the in vitro activity. Moreover, both the C-terminal truncation and the elimination of the N-glycosylation sites decreased the secretion level progressively down to (1)/(10) that of wild type, and the amount of the mutant left in the cell increased. The N-glycosylation in the C-terminal region was found to be important for secretion of TPO. Among six N-glycosylation sites in the C-terminal region, two locations, Asn-213 and Asn-234, were found to be critical for secretion, and two other locations, Asn-319 and Asn-327, did not affect the secretion. 相似文献
88.
Growth control of epithelial cells differs substantially from other cell types. Activation of Fyn, a Src kinase family member, is required for normal keratinocyte differentiation. We report that increased Fyn activity by itself suppresses growth of keratinocytes, but not dermal fibroblasts, through downmodulation of EGF receptor (EGFR) signaling. Protein kinase C-eta has also been implicated in keratinocyte growth/differentiation control. We show that growth suppression of keratinocytes by PKC-eta depends mostly on Fyn. PKC-eta activity is both necessary and sufficient for Fyn activation, PKC-eta and Fyn are found in association, and recombinant PKC-eta directly activates Fyn. Thus, our findings reveal a direct cross talk between PKC-eta and Fyn, which presides over the decision between keratinocyte (epithelial) cell growth and differentiation. 相似文献
89.
Icatlo FC Yokoyama H Kuroki M Kobayashi C Goshima H Ikemori Y Kodama Y 《Microbiology and immunology》2000,44(9):773-776
Colonization by Helicobacter pylori partly depends on acid-dependent adherence by urease to gastric mucin. To further verify the relevance of urease adherence to colonization, the influence of acidity on the binding sites of H. pylori urease was investigated. When enzyme-based in vitro ligand capture assays were used, the effect of acidity on the binding site of H. pylori urease was determined against a backdrop medium consisting of acidic buffers simulating the luminal side of gastric mucus. A high degree of stability was exhibited by adherent urease, suggesting a pivotal role by the denatured enzyme in the persistence of the bacterium within the acidified compartment of gastric mucus. 相似文献
90.