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排序方式: 共有134条查询结果,搜索用时 421 毫秒
91.
W Tienrungroj S E Pratt J F Grippo A Holmgren W B Pratt 《Journal of steroid biochemistry》1987,28(5):449-457
Treatment of rat liver cytosol containing temperature-transformed [3H]dexamethasone-bound receptors at 0 degree C with the sulfhydryl modifying reagent methyl methanethiosulfonate (MMTS) inhibits the DNA-binding activity of the receptor, and DNA-binding activity is restored after addition of dithiothreitol (DTT). However, transformed receptors that are treated with MMTS and then separated from low Mr components of cytosol by passage through a column of Sephadex G-50 have very little DNA-binding activity when DTT is added to regenerate sulfhydryl moities. The receptors will bind to DNA if whole liver cytosol or boiled liver cytosol is added in addition to DTT. The effect of boiled cytosol is mimicked by purified rat thioredoxin or bovine RNase A in a manner that does not reflect the reducing activity of the former or the catalytic activity of the latter. This suggests that the reported ability of each of these heat-stable peptides to stimulate DNA binding by glucocorticoid receptors is not a biologically relevant action. We suggest that stimulation of DNA binding of partially purified receptors by boiled cytosol does not constitute a reconstitution of a complete cytosolic system in which the dissociated receptor must associate with a specific heat-stable accessory protein required for DNA binding, as has been suggested in the "two-step" model of receptor transformation recently proposed by Schmidt et al. (Schmidt T.J., Miller-Diener, A., Webb M.L. and Litwack G. (1985) J. biol. Chem. 260, 16255-16262). 相似文献
92.
The kinetics of manganese(II) ion uptake and efflux have been investigated using tracer54Mn(II) with glial cells cultured from chick cerebral cortex in chemically defined medium. The initial velocity of Mn(II) uptake versus [Mn(II)] exhibit saturation, with an apparent S0.518(±3) M. Both the rate and extent of Mn(II) uptake are inhibited by Ca(II), either added externally or preloaded into the glial cells. Preloading of glia with Mn(II) also inhibits the rate of external54Mn(II) uptake. Zn(II) inhibits but Cu(II) activates Mn(II) uptake. Efflux of Mn(II) from preloaded cells occurs as a biphasic process, with rapid release of 30–40% of total cell Mn(II), then much slower release of the remainder. Permeabilization of cells with dextran sulfate also rapidly released ca. 30% of total cell Mn(II). High external Mn(II) enhanced both the rate and extent of Mn(II) efflux. CCCP, an uncoupler of oxidative phosphorylation, inhibited both Mn(II) uptake and efflux significantly, but addition of cyanide, ouabain, insulin, hydrocortisone, K+, or Nd(III) had no effect on either process. Taken together, these data suggest a model in which Mn(II) is brought across the plasma membrane by facilitated diffusion, binds to cytosolic protein sites, and is partitioned into the mitochondria by an active transport mechanism. The fact that the Mn(II) flux rates observed with cultured glia are much faster than those reported for overall uptake and efflux of brain Mn(II)in vivo suggests that the blood-brain barrier may play a significant role in determining these latter rates in whole animals.Supported in part by NIH grant GM-33358 and a Biomedical Research Support Grant from the NIH administered by Penn State. 相似文献
93.
DNA replication during muscle cell differentiation: identification of multiple DNA-dependent DNA polymerases 总被引:1,自引:0,他引:1
DNA-dependent DNA polymerases have been studied during chick embryo muscle differentiation in vitro. The total activity, extracted at both low and high ionic strengths, does not change throughout the differentiative process, although DNA synthesis stops at the moment of fusion. Analyses by glycerol gradient centrifugation of the extracts at low and high ionic strengths show two major DNA polymerase forms, one sedimenting at 7.5 S and another at 3-4 S. Both enzymes are present in similar amounts in duplicating myoblasts and in post-mitotic myotubes. These data suggest that the arrest of DNA synthesis which accompanies myoblast differentiation is not dependent on the disappearance or decrease of the major DNA polymerase activities described. 相似文献
94.
95.
Adhemar Longatto Filho Tiago Gil Oliveira Céline Pinheiro Marcos Brasilino de Carvalho Otávio Alberto Curioni Ana Maria da Cunha Mercante Fernando C Schmitt Gilka JF Gattás 《World journal of surgical oncology》2007,5(1):140
Background
Lymphatic vessels are major routes for metastasis in head and neck squamous cell carcinoma (HNSCC), but lymphatic endothelial cells (LECs) are difficult to recognize in tumor histological sections. D2-40 stains podoplanin, a molecule expressed in LECs, however, the potential prognostic usefulness of this molecule is not completely understood in HNSCC. We aimed to investigate the value of assessing peritumoral and intratumoral lymphatic vessel density (LVD) as prognostic marker for HNSCC.Methods
Thirty-one cases of HNSCC were stained for D2-40 and CD31. LVD and blood vessel density (BVD) were assessed by counting positive reactions in 10 hotspot areas at ×200 magnification.Results
D2-40 was specific for lymphatic vessels and did not stain blood vascular endothelial cells. LECs showed more tortuous and disorganized structure in intratumoral lymphatic vessels than in peritumoral ones. No statistical differences were observed between peritumoral-LVD and intratumoral-LVD or between peritumoral-BVD and intratumoral-BVD. Tumor D2-40 staining was positively associated with lymphatic vessel invasion (p = 0.011).Conclusion
LVD is a powerful marker for HNSCC prognosis. We found significant differences in peritumoral and intratumoral D2-40 immunoreactivity, which could have important implications in future therapeutic strategies and outcome evaluation.96.
Saskia I. Johanns Richard G. Gantin Bawoubadi Wangala Kossi Komlan Wemboo A. Halatoko Meba Banla Potchoziou Karabou Adrian JF Luty Hartwig Schulz-Key Carsten Khler Peter T. Soboslay 《PLoS neglected tropical diseases》2022,16(5)
BackgroundAnnual mass drug administrations (MDA) of ivermectin will strongly reduce Onchocerca volvulus microfilariae (mf) in the skin and in the onchocerciasis patients’ eyes. Ivermectin treatment will also affect the expression of immunity in patients, such that activated immune defenses may help control and contribute to clearance of mf of O. volvulus. Longitudinal surveys are a prerequisite to determining the impact of ivermectin on the status of anti-parasite immunity, notably in risk zones where parasite transmission and active O. volvulus infections persist.Methodology/Principal findingsOnchocerciasis patients were treated annually with ivermectin and their Onchocerca volvulus antigen (OvAg) specific IgG and cellular responses were investigated before and at 30 years post initial ivermectin treatment (30yPT).Repeated annual ivermectin treatments eliminated persisting O. volvulus microfilariae (mf) from the skin of patients and abrogated patent infections. The OvAg-specific IgG1 and IgG4 responses were diminished at 30yPT to the levels observed in endemic controls. Prior to starting ivermectin treatment, OvAg-induced cellular productions of IL-10, IFN-γ, CCL13, CCL17 and CCL18 were low in patients, and at 30yPT, cellular cytokine and chemokine responses increased to the levels observed in endemic controls. In contrast, mitogen(PHA)- induced IL-10, IFN-γ, CCL17 and CCL18 cellular production was diminished. This divergent response profile thus revealed increased parasite antigen-specific but reduced polyclonal cellular responsiveness in patients. The transmission of O. volvulus continued at the patients’ location in the Mô river basin in central Togo 2018 and 2019 when 0.58% and 0.45%, respectively, of Simulium damnosum s.l. vector blackflies carried O. volvulus infections.Conclusions/SignificanceRepeated annual ivermectin treatment of onchocerciasis patients durably inhibited their patent O. volvulus infections despite ongoing low-level parasite transmission in the study area. Repeated MDA with ivermectin affects the expression of immunity in patients. O. volvulus parasite-specific antibody levels diminished to levels seen in infection-free endemic controls. With low antibody levels, antibody-dependent cellular cytotoxic responses against tissue-dwelling O. volvulus larvae will weaken. O. volvulus antigen inducible cytokine and chemokine production increased in treated mf-negative patients, while their innate responsiveness to mitogen declined. Such lower innate responsiveness in elderly patients could contribute to reduced adaptive immune responses to parasite infections and vaccines. On the other hand, increased specific cellular chemokine responses in mf-negative onchocerciasis patients could reflect effector cell activation against tissue invasive larval stages of O. volvulus. The annual Simulium damnosum s.l. biting rate observed in the Mô river basin was similar to levels prior to initiation of MDA with ivermectin, and the positive rtPCR results reported here confirm ongoing O. volvulus transmission. 相似文献
97.
Artim John M. Hook Alexandra Grippo Richard S. Sikkel Paul C. 《Coral reefs (Online)》2017,36(4):1213-1223
Coral Reefs - On coral reefs, gnathiid isopods are a common blood-feeding ectoparasite of reef fishes that can have significant impacts on reef-fish health and fitness. Cleaner fishes and shrimps... 相似文献
98.
Deoxyribonucleic acid polymerase of bacteriophage T7 总被引:22,自引:0,他引:22
99.
Identification of a DNA polymerase beta-like form in Drosophila melanogaster adult flies. 总被引:2,自引:0,他引:2
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DNA polymerase beta is widely distributed in the eukariotes. So far, few examples are known in which a DNA polymerase alpha -like form alone is reported. Surprisingly, DNA polymerase beta was not detected in Drosophila embryos, while it is present in the cells of multicellular species from sponge to mammals. In view of the relevance of Drosophila as a model biological system for studying the role of the various DNA metabolism enzymes in vivo we have reinvestigated the presence of the DNA polymerase beta-like form in Drosophila adult flies.Here we report the occurrence in Drosophila melanogaster adult flies of a DNA polymerase activity that, for its NEM(1) resistance, template specificity, sensitivity to ddTTP, sedimentation coefficient and nuclear localization can be classified as a beta-like form. 相似文献
100.
Quezada-Rivera JJ RE Soria-Guerra FS Pérez-Juárez L Martínez-González SE Valdés- Rodríguez NL Vasco-Méndez JF Morales-Domínguez 《Phyton》2019,88(1):25-35
The use of antimicrobial peptides (AMPs) synthesized
by bacteria (bacteriocins) is an alternative for combating multidrug
resistant bacterial strains and their production by recombinant route
is a viable option for their mass production. The bacteriocin E-760
isolated from the genus Enterococcus sp. has been shown to possess
inhibitory activity against Gram-negative and Gram-positive
bacteria. In this study, the expression of a chimeric protein coding
for E-760 in the nucleus of C. reinhardtii was evaluated, as well as,
its antibacterial activity. The synthetic gene E-760S was inserted
into the genome of C. reinhardtii using Agrobacterium tumefaciens.
A transgenic line was identified in TAP medium with hygromycin
and also by PCR. The increment in the culture medium temperature
of the transgenic strain at 35 °C for 10 minutes, increased the
production level of the recombinant protein from 0.14 (Noninduced
culture, NIC) to 0.36% (Induced culture, IC) of total soluble
proteins (TSP); this was quantified by an ELISA assay. Recombinant
E-760 possesses activity against Staphylococcus aureus in 0.34 U
log, Streptococcus agalactiae in 0.48 U log, Enterococcus faecium in
0.36 U log, Pseudomonas aeruginosa in 2 U log and for Klebsiella
pneumoniae, the activity was 0.07 U log. These results demonstrate
that the nucleus transformation of C. reinhardtii can function as
a stable expression platform for the production of the synthetic
gene E-760 and it can potentially be used as an antibacterial agent. 相似文献