共查询到20条相似文献,搜索用时 15 毫秒
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Alice V. Bakker June Daffeh Stanley Jung Lawrence A. Vincent Arthur A. Nagel Robin W. Spencer Fredric J. Vinick W. Stephen Faraci 《Bioorganic & medicinal chemistry letters》1991,1(11)
Inhibition of prolyl endopeptidase by Z-cyclohexyl prolinal and Z-indolinyl prolinal occurs with slow, tight binding inhibition and Ki values of 2 – 3 nM. In vivo enzyme inhibition is also observed with a half time for recovery of enzyme activity of 3 – 4 h.Inhibition of prolyl endopeptidase by Z-cyclohexyl prolinal and Z-indolinyl prolinal occurs with slow, tight binding inhibition and Ki values of 2 – 3 nM. In vivo enzyme inhibition is also observed with a half time for recovery of enzyme activity of 3 – 4 h. 相似文献
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Herman Adlercreutz Yaghoob Mousavi Jim Clark Krister Hckerstedt Esa Hmlinen Kristiina Whl Taru Mkel Tapio Hase 《The Journal of steroid biochemistry and molecular biology》1992,41(3-8)
Thirty postmenopausal women (11 omnivores, 10 vegetarians and 9 apparently healthy women with surgically removed breast cancer) were investigated with regard to the association of their urinary excretion of estrogens, lignans and isoflavonoids (all diphenols) with plasma sex hormone binding globulin (SHBG). A statistically significant positive correlation between urinary total diphenol excretion and plasma SHBG was found which remained statistically significant after elimination of the confounding effect of body mass determined by body mass index (BMI). Furthermore we found a statistically significant negative correlation between plasma SHBG and urinary excretion of 16α-hydroxyestrone and estriol which also remained significant after eliminating the effect of BMI. Furthermore we observed that enterolactone (Enl) stimulates the synthesis of SHBG by HepG2 liver cancer cells in culture acting synergistically with estradiol and at physiological concentrations. Enl was rapidly conjugated by the liver cells, mainly to its monosulfate. Several lignans and the isoflavonoids daidzein and equol were found to compete with estradiol for binding to the rat uterine type II estrogen binding site (the s.c. bioflavonoid receptor). It is suggested that lignans and isoflavonoids may affect uptake and metabolism of sex hormones by participating in the regulation of plasma SHBG levels and in this way influence their biological activity and that they may inhibit cancer cell growth like some flavonoids by competing with estradiol for the type II estrogen binding sites. 相似文献
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单核细胞增生李斯特氏菌(Listeria monocytogenes)是重要的食源性致病菌,能引发人类的李斯特菌病,是全球公共卫生问题之一。该菌易感染孕妇,引起胎儿和新生儿的侵袭性李斯特菌病,严重威胁母婴健康。因此,建立有效的单增李斯特菌感染胎盘体内外模型,解析和探究单增李斯特菌经胎盘感染机制,是预防和控制单增李斯特菌感染母婴的关键所在。本文综述了可用于研究单增李斯特菌母婴感染的体内外胎盘模型,总结和讨论了各类模型的优势和局限性;并着重分析了体外三维胎盘屏障模型在单增李斯特菌感染方面的研究进展和未来研究方向。以期为深入解析该菌经胎盘感染的途径、发病机制提供支持,并为预防和控制母婴李斯特菌病提供科学参考。 相似文献
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The phagocytic ability of carp (Cyprinus carpio L.) granulocytes was evaluated in vivo and in vitro. In suspensions of head kidney cells, neutrophil granulocytes incorporated both latex beads and coccidian merozoites. In intestinal tissues from carp with a Goussia carpelli infection, all granulocyte cell types (neutrophils and cells of the basophilic-eosinophilic complex) phagocytosed cell detritus and coccidian developmental stages, mainly merozoites. 相似文献
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E. Haehling J. Y. Niederkorn G. L. Stewart 《International journal for parasitology》1995,25(12):1393-1400
Immunoperoxidase staining of muscle infected with Trichinella spiralis for murine collagen types I and IV provided both qualitative and quantitative evidence of extensive synthesis of both types of collagen by fibroblasts in infected muscle compared to that seen uninfected muscle. Moreover, fibroblasts in muscle infected with T. pseudospiralis, a nonencapsulating species, showed significantly less staining for both types of collagen compared to muscle from mice infected with T. spiralis. Analysis of collagen composition of isolated nurse cells using an ELISA specific for either type I or type IV murine collagen suggested that of these 2 types of collagen, only type IV basement membrane collagen is found in Trichinella capsular collagen. Excretory/secretory products of T. spiralis and T. pseudospiralis induced extensive synthesis of exclusively type IV collagen by 3T3 murine fibroblasts in vitro. 相似文献
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Exposure of endothelium to a nominally uniform flow field in vivo and in vitrofrequently results in a heterogeneous distribution of individual cell responses. Extremes in response levels are often noted in neighboring cells. Such variations are important for the spatial interpretation of vascular responses to flow and for an understanding of mechanotransduction mechanisms at the level of single cells. We propose that variations of local forces defined by the cell surface geometry contribute to these differences. Atomic force microscopy measurements of cell surface topography in living endothelium both in vitro and in situ combined with computational fluid dynamics demonstrated large cell-to-cell variations in the distribution of flow-generated shear stresses at the endothelial luminal surface. The distribution of forces throughout the surface of individual cells of the monolayer was also found to vary considerably and to be defined by the surface geometry. We conclude that the endothelial three-dimensional surface geometry defines the detailed distribution of shear stresses and gradients at the single cell level, and that there are large variations in force magnitude and distribution between neighboring cells. The measurements support a topographic basis for differential endothelial responses to flow observed in vivo and in vitro. Included in these studies are the first preliminary measurements of the living endothelial cell surface in an intact artery. 相似文献
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Stephen P. Ethier Rochelle M. Van De Velde Kimberly C. Cundiff 《Experimental cell research》1989,182(2)
Agents that elevate intracellular cAMP levels are required for growth of many cell types in culture including normal rat mammary epithelial (RME) cells. To determine if the intracellular levels of cAMP that result from stimulation by agents such as cholera toxin (CT) or prostaglandin E-1 (PGE-1) are within the physiological range, cAMP levels were determined in RME cells growing in primary culture and compared to levels measured in freshly isolated mammary epithelium. The results indicate that the cAMP levels of mammary epithelial organoids obtained from 45-day-old virgin rats are 4 to 6 pmol/106 cells. Growth of RME cells in primary culture in the presence of CT results in cAMP levels of approximately 15 to 20 pmol/106 cells early in culture when cells are proliferating rapidly. As cells approach confluence, cAMP concentrations decrease to levels observed in fresh organoids. CT-stimulated cAMP levels appear to be within the range of those found in pregnant mammary epithelium in vivo. Growth of RME cells in medium supplemented with PGE-1 instead of CT results in cAMP levels equivalent to those found in fresh mammary epithelial organoids and under these conditions the growth rate is approximately half that found in CT-stimulated cells. These results indicate cAMP to be a positive regulator of cell growth in vivo at levels that are within the physiological range. 相似文献
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斑马鱼(zebrafish,Danio rerio)是生物学领域中公认的研究脊椎类生物的模式生物.胸苷酸合成酶(thymidylate synthase,TS)是DNA从头合成的限速酶,多年来一直作为肿瘤化疗的重要靶酶.前期的研究表明,人和大肠杆菌中TS能与自身的mRNA结合,在翻译水平上具有反馈抑制自调控现象.斑马鱼作为药物模型的研究已成为热点研究领域,为了探讨斑马鱼的胸苷酸合成酶的调控规律,以及与人TS的相关性,利用原核表达,纯化获得高均一性斑马鱼TS蛋白,采用凝胶迁移研究了TS和其mRNA的体外结合,采用免疫共沉淀:RT-PCR技术研究了它们在体内的相互作用,实验结果表明,斑马鱼的TS在体内外均与自身的mRNA存在特异性的相互作用.研究说明,斑马鱼和人的TS具有高度生物学过程相关性,为构建斑马鱼抗肿瘤药理模型提供了理论基础. 相似文献
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To determine if hormone-induced events leading to ovulation an granulosa cell luteinization might be associated with changes in the surface configuration of granulosa cells we have studied the morphology of granulosa cells from the preovulatory follicles both in vivo and in vitro. In vivo, granulosa cells in follicles from rats primed with estradiol and FSH developed bulbous protrusions termed blebs in response to injected hCG. The blebs were restricted to the adluminal granulosa cells which possess the least number of receptors for hCG. When granulosa cells from follicles of rats primed with estradiol and FSH were cultured in vitro, in the absence of serum, approximately 10% of the cells formed blebs. In the presence of 10% rat or fetal calf serum, nearly 90% of the cells formed blebs by 18 hr. Serum-induced bleb formation was prevented by 1 mM dibutyryl cycle-AMP plus 0.5 mM methyl isobutyl xanthine and by cytochalasin B (25 mug/ml), while 0.1 muM colchicine had no effect. Fibronectin at 25 mug/ml increased bleb formation three-fold over control values in serum-free medium. When hCG was included in serum containing medium, the majority of the cells remained smooth without any blebs. Thus, in contrast to its action in vivo, hCG inhibited the formation of blebs in vitro. When the cells incubated in the presence of dbcAMP plus methyl isobutyl xanthine in serum-containing medium, none of the cells formed blebs. One explanation for the seemingly opposite actions of hCG in vivo and in vitro is that hCG might act to alter the permeability of the pre-ovulatory follicles, and thereby allow the admission of serum. The admitted serum component(s) could then induce the formation of blebs on receptor-deficient adluminal cells that did not have elevated cAMP concentrations. The results suggest that fibronectin and/or other serum components, act to induce microfilament-dependent, cAMP-inhibited bleb formation on granulosa cells in vivo and in vitro. 相似文献
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To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettesin vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ribozyme embedded into the human snRNA U6, and detected the activity of the ribozymein vitro andin vivo. Meanwhile we compared it with the self-cleaving hammerhead ribozymes that we previously studied, and with the general ribozyme, cloned into RNA polymerase II expression systems. The results showed that the three ribozymes, p1.5RZ107, pRZ107 and pU6RZ107 had the correct structure, and that they could cleave caspase-3 mRNA exactly to produce two fragments: 143nt/553nt. p1.5RZ107 has the highest cleavage efficiencyin vitro, almost 80%. However, the U6 chimeric ribozyme, pU6RZ107, has the highest cleavage activityin vivo, almost to 65%, though it has lower cleavage activityin vitro. The cleavage results demonstrated that the pU6RZ107, the U6 chimeric ribozyme, could more efficiently express and downregulate the level of caspase-3in vivo, and the ribozyme could provide an alternative approach to the research into the mechanism of apoptosis and human gene therapy also. 相似文献
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Ji-Yuan Sun Hao Yang Shan Miao Ji-Peng Li Si-Wang Wang Miao-Zhang Zhu Yan-Hua Xie Jian-Bo Wang Zhe Liu Qian Yang 《Phytomedicine》2009,16(11):1070-1074
Swainsonine, an extract from Astragalus membranaceus, is known for its anti-cancer effects and could prevent metastases. In order to investigate the effects and mechanisms of swainsonine in C6 glioma cells, we carry out correlated experiments in vitro and in vivo. After treatment with swainsonine, the effective dose and IC50 value of swainsonine in the C6 glioma cell were examined using the MTT assay. Cell cycle distribution and apoptotic rates were analyzed using FCM and [Ca2+]i was measured by LSCM. Expressions of p16 and p53 protein were evaluated by immunocytochemical methods. Simultaneously, glioma-bearing rats were administered swainsonine at doses of 2, 4 and 8 mg/kg body wt. The inhibition rate was calculated and pathological sections were observed. The results indicated that the growth of C6 glioma cells is inhibited by swainsonine in vitro, with an IC50 value within 24 h of 0.05 μg/ml. Increases in swainsonine correlate with S phase percentages of 11.3%, 11.6% and 12.4%, respectively. Moreover, the expression of apoptosis inhibiting p53 and p16 protein decreases gradually. Tumor weight in vivo decreased clearly and HE dyeing of tumor tissue showed gray, its texture was soft, with necrosis and hemorrhagic concentrated inward. Swainsonine could inhibit the proliferation of C6 glioma cells in vitro and the growth of C6 glioma in vivo. The mechanisms of swainsonine-induced apoptosis may relate with the expression of apoptosis-related genes and overloading-[Ca2+]i-induced endoplasmic reticulum stress. 相似文献
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H.J. Kloosterboer W.G.E.J. Schoonen G.H. Deckers J.G.M. Klijn 《The Journal of steroid biochemistry and molecular biology》1994,49(4-6):311-318
Sex steroids, in particular estradiol (E2) and progesterone (P4), play, together with other hormones and growth factors, a role in the development of normal breast tissue. The effect of four progestagens (norethisterone, 3-ketodesogestrel, gestodene and P4) and Org OD14, a steroid with weak estrogenic, progestagenic and androgenic properties were studied on growth of breast tumor cells in vitro using two subclones of MCF-7 (H and A) and T47D (S and A) cells. In addition, we investigated the effects of 3-ketodesogestrel, gestodene and Org OD14 on the growth of 7,12-dimethyl-benz(a)anthracene(DMBA)-induced mammary tumors in rats. In the in vitro assays with MCF-7 cells norethisterone, 3-ketodesogestrel and gestodene stimulated growth only at high doses (10−7 M), whereas P4 had no effect. Gestodene was more potent than 3-ketodesogestrel and norethisterone. Org OD14, stimulated cell growth at a dose of 10−8 M, while E2 is active at 10−10 M. In T47D-A cells similar effects were found, but the subclone S did not respond to the progestagens and Org OD14. The two T47D subclones also reacted differently to progestagens during growth stimulation with E2. In T47D-S the progestagens and Org OD14 inhibited, while in T47D-A these compounds did not modulate the effect of E2. In the DMBA model we found that gestodene and 3-ketodesogestrel were able to inhibit tumor growth to the same extent. Surprisingly, Org OD14 was even more effective in the DMBA model using the therapeutic approach. Using the prophylaxic approach tumor development was delayed and tumor growth was strongly suppressed. The inhibitory effects of Org OD14 on tumor growth in the DMBA model may be attributed to its mixed hormonal profile. From these studies we conclude that different cell lines and even subclones thereof respond quite differently to steroids. Both in vitro and in vivo studies are required to judge whether synthetic steroids might be involved in an increased risk for the development of breast tumors. 相似文献
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Streptococcus thermophilus is a thermophilic gram-positive bacterium belonging to the lactic acid group. We report the isolation and characterization of a new 9.6-kDa DNA-binding protein, HSth, belonging to the HU family of nucleoid-associated proteins. The hsth gene was isolated in a 2.5-kb genomic region, upstream of a gene with strong homology to Lactococcus lactis pyrD. It is transcribed from a single E. coli sigma(70)-like promoter. Based on its high level of sequence similarity to B. subtilis and E. coli HU, HSth appears to be an HU homologue. The HSth protein shows biochemical and functional properties typical of HU proteins from gram-positive bacteria, being heat-stable, acid-soluble, and homodimeric. When expressed in HU-deficient E. coli cells, HSth supported the growth of bacteriophage Mu as efficiently as E. coli HU homo- and heterodimeric proteins. It did not, however, display any IHF-specific functions. Finally, we show that HSth binds to linear DNA with no apparent specificity, forming protein-DNA complexes similar but not identical to those observed with E. coli HU proteins. 相似文献
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Haim Leibovich Nina Raver Asael Herman Ewa L. Gregoraszczuk Elisha Gootwine Arieh Gertler 《Protein expression and purification》2001,22(3):489
Recombinant bovine Ala-prolactin (PRL) (GenBank Accession No. V00112) in prokaryotic expression plasmid pMON3401 was mutated using a mutagenesis kit, to prepare plasmid encoding ovine PRL (oPRL) (GenBank Accession No. M27057) Escherichia coli cells transformed with this latter plasmid overexpressed large amounts of oPRL upon induction with nalidixic acid. The expressed protein, found in inclusion bodies, was refolded and purified to homogeneity on a Q-Sepharose column, yielding an electrophoretically pure fraction composed of over 98% monomeric protein of the expected molecular mass of 23 kDa. The biological activity of the recombinant oPRL after proper renaturation was evidenced in vitro by its ability to stimulate proliferation of rat lymphoma Nb2 cells possessing PRL receptors, to stimulate luciferase activity in HEK 293 cells transiently transfected with oPRL receptors, and to induce progesterone secretion in primary cultures of luteal cells obtained from midpregnant ewes. In contrast to ovine growth hormone or ovine placental lactogen, recombinant oPRL had no galactopoietic effect in lactating ewes. 相似文献