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排序方式: 共有121条查询结果,搜索用时 390 毫秒
1.
Annette Burkhart Thomas Lars Andresen Achim Aigner Louiza Bohn Thomsen Torben Moos 《Cellular and molecular life sciences : CMLS》2017,74(13):2467-2485
Treatment of chronic disorders affecting the central nervous system (CNS) is complicated by the inability of drugs to cross the blood–brain barrier (BBB). Non-viral gene therapy applied to brain capillary endothelial cells (BCECs) denotes a novel approach to overcome the restraints in this passage, as turning BCECs into recombinant protein factories by transfection could result in protein secretion further into the brain. The present study aims to investigate the possibility of transfecting primary rat brain endothelial cells (RBECs) for recombinant protein synthesis and secretion of the neuroprotective protein erythropoietin (EPO). We previously showed that 4% of RBECs with BBB properties can be transfected without disrupting the BBB integrity in vitro, but it can be questioned whether this is sufficient to enable protein secretion at therapeutic levels. The present study examined various transfection vectors, with regard to increasing the transfection efficiency without disrupting the BBB integrity. Lipofectamine 3000? was the most potent vector compared to polyethylenimine (PEI) and Turbofect. When co-cultured with astrocytes, the genetically modified RBECs secreted recombinant EPO into the cell culture medium both luminally and abluminally, and despite lower levels of EPO reaching the abluminal chamber, the amount of recombinant EPO was sufficient to evolve a biological effect on astrocytes cultured at the abluminal side in terms of upregulated gene expression of brain-derived neurotropic factor (BDNF). In conclusion, non-viral gene therapy to RBECs leads to protein secretion and signifies a method for therapeutic proteins to target cells inside the CNS otherwise omitted due to the BBB. 相似文献
2.
Kharchenko PV Alekseyenko AA Schwartz YB Minoda A Riddle NC Ernst J Sabo PJ Larschan E Gorchakov AA Gu T Linder-Basso D Plachetka A Shanower G Tolstorukov MY Luquette LJ Xi R Jung YL Park RW Bishop EP Canfield TK Sandstrom R Thurman RE MacAlpine DM Stamatoyannopoulos JA Kellis M Elgin SC Kuroda MI Pirrotta V Karpen GH Park PJ 《Nature》2011,471(7339):480-485
Chromatin is composed of DNA and a variety of modified histones and non-histone proteins, which have an impact on cell differentiation, gene regulation and other key cellular processes. Here we present a genome-wide chromatin landscape for Drosophila melanogaster based on eighteen histone modifications, summarized by nine prevalent combinatorial patterns. Integrative analysis with other data (non-histone chromatin proteins, DNase I hypersensitivity, GRO-Seq reads produced by engaged polymerase, short/long RNA products) reveals discrete characteristics of chromosomes, genes, regulatory elements and other functional domains. We find that active genes display distinct chromatin signatures that are correlated with disparate gene lengths, exon patterns, regulatory functions and genomic contexts. We also demonstrate a diversity of signatures among Polycomb targets that include a subset with paused polymerase. This systematic profiling and integrative analysis of chromatin signatures provides insights into how genomic elements are regulated, and will serve as a resource for future experimental investigations of genome structure and function. 相似文献
3.
Recognition of protein structure in leukocyte chemotaxis 总被引:5,自引:0,他引:5
P C Wilkinson 《Nature》1973,244(5417):512-513
4.
Fromhold TM Patanè A Bujkiewicz S Wilkinson PB Fowler D Sherwood D Stapleton SP Krokhin AA Eaves L Henini M Sankeshwar NS Sheard FW 《Nature》2004,428(6984):726-730
Understanding how complex systems respond to change is of fundamental importance in the natural sciences. There is particular interest in systems whose classical newtonian motion becomes chaotic as an applied perturbation grows. The transition to chaos usually occurs by the gradual destruction of stable orbits in parameter space, in accordance with the Kolmogorov-Arnold-Moser (KAM) theorem--a cornerstone of nonlinear dynamics that explains, for example, gaps in the asteroid belt. By contrast, 'non-KAM' chaos switches on and off abruptly at critical values of the perturbation frequency. This type of dynamics has wide-ranging implications in the theory of plasma physics, tokamak fusion, turbulence, ion traps, and quasicrystals. Here we realize non-KAM chaos experimentally by exploiting the quantum properties of electrons in the periodic potential of a semiconductor superlattice with an applied voltage and magnetic field. The onset of chaos at discrete voltages is observed as a large increase in the current flow due to the creation of unbound electron orbits, which propagate through intricate web patterns in phase space. Non-KAM chaos therefore provides a mechanism for controlling the electrical conductivity of a condensed matter device: its extreme sensitivity could find applications in quantum electronics and photonics. 相似文献
5.
The Earth's climate has undergone a global transition over the past four million years, from warm conditions with global surface temperatures about 3 degrees C warmer than today, smaller ice sheets and higher sea levels to the current cooler conditions. Tectonic changes and their influence on ocean heat transport have been suggested as forcing factors for that transition, including the onset of significant Northern Hemisphere glaciation approximately 2.75 million years ago, but the ultimate causes for the climatic changes are still under debate. Here we compare climate records from high latitudes, subtropical regions and the tropics, indicating that the onset of large glacial/interglacial cycles did not coincide with a specific climate reorganization event at lower latitudes. The regional differences in the timing of cooling imply that global cooling was a gradual process, rather than the response to a single threshold or episodic event as previously suggested. We also find that high-latitude climate sensitivity to variations in solar heating increased gradually, culminating after cool tropical and subtropical upwelling conditions were established two million years ago. Our results suggest that mean low-latitude climate conditions can significantly influence global climate feedbacks. 相似文献
6.
HIV preferentially infects HIV-specific CD4+ T cells 总被引:34,自引:0,他引:34
Douek DC Brenchley JM Betts MR Ambrozak DR Hill BJ Okamoto Y Casazza JP Kuruppu J Kunstman K Wolinsky S Grossman Z Dybul M Oxenius A Price DA Connors M Koup RA 《Nature》2002,417(6884):95-98
HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption. 相似文献
7.
8.
In occupational therapy education in South Africa, community service (CS) focuses learning opportunities during fieldwork
placements. CS therefore enabled the researcher to utilise successive small scale research projects to guide learning of students
during fieldwork while simultaneously developing the occupational therapy service at a residential care facility. This community
setting provided a powerful environment through which research, in combination with opportunities for reflection, contributed
to nurturing skills needed by these future health professionals. A technical action research (AR) approach incorporated AR
cycles and opportunities for structured reflection. Therefore situations were created for the students to embrace experiential
learning. Experiential learning in the form of anticipatory reflection, reflection-in-action, reflection on reflection and
retrospective reflection impacted on the quality of the students’ work. Besides encouraging unique leaning opportunities for
students when engaging in research during their fieldwork placement, engagement in AR cycles simultaneously improved service
delivery to residents in the facility. Key benefits of this investigation were that fieldwork education utilising AR cycles
within a CS situation promoted students to identify voids in their theoretical background as well as practice skills; to apply
reflective practice that could contribute to their personal and professional development; and to utilize learning opportunities
optimally. Despite positive gains showed by this study, the role of power relations between the researcher as fieldwork educator
and the students prohibited the AR cycles from being more emancipatory in nature and should be addressed in follow-up studies. 相似文献
9.
Maria C. Shina Annette Müller-Taubenberger Can Ünal Michael Schleicher Michael Steinert Ludwig Eichinger Rolf Müller Rosemarie Blau-Wasser Gernot Glöckner Angelika A. Noegel 《Cellular and molecular life sciences : CMLS》2011,68(2):303-313
Dictyostelium discoideum harbors a short (CRN12) and a long coronin (CRN7) composed of one and two beta-propellers, respectively. They are primarily
present in the cell cortex and cells lacking CRN12 (corA
−) or CRN7 (corB
−) have defects in actin driven processes. We compared the characteristics of a mutant cell line (corA
−
/corB
−) lacking CRN12 and CRN7 with the single mutants focusing on cytokinesis, phagocytosis, chemotaxis and development. Cytokinesis,
uptake of small particles, and developmental defects were not enhanced in the corA
−
/corB
− strain as compared to the single mutants, whereas motility and phagocytosis of yeast particles were more severely impaired.
It appears that although both proteins affect the same processes they do not act in a redundant manner. Rather, they often
act antagonistically, which is in accordance with their proposed roles in the actin cytoskeleton where CRN12 acts in actin
disassembly whereas CRN7 stabilizes actin filaments and protects them from disassembly. 相似文献
10.
John T. Heiker Nora Klöting Peter Kovacs E. Bartholomeus Kuettner Norbert Sträter Stephan Schultz Matthias Kern Michael Stumvoll Matthias Blüher Annette G. Beck-Sickinger 《Cellular and molecular life sciences : CMLS》2013,70(14):2569-2583
The molecular target of the adipokine vaspin (visceral adipose tissue-derived serpin; serpinA12) and its mode of action are unknown. Here, we provide the vaspin crystal structure and identify human kallikrein 7 (hK7) as a first protease target of vaspin inhibited by classical serpin mechanism with high specificity in vitro. We detect vaspin–hK7 complexes in human plasma and find co-expression of both proteins in murine pancreatic β-cells. We further demonstrate that hK7 cleaves human insulin in the A- and B-chain. Vaspin treatment of isolated pancreatic islets leads to increased insulin concentration in the media upon glucose stimulation without influencing insulin secretion. By application of vaspin and generated inactive mutants, we find the significantly improved glucose tolerance in C57BL/6NTac and db/db mice treated with recombinant vaspin fully dependent on the vaspin serpin activity and not related to vaspin-mediated changes in insulin sensitivity as determined by euglycemic-hyperinsulinemic clamp studies. Improved glucose metabolism could be mediated by increased insulin plasma concentrations 150 min after a glucose challenge in db/db mice, supporting the hypothesis that vaspin may inhibit insulin degradation by hK7 in the circulation. In conclusion, we demonstrate the inhibitory serpin nature and the first protease target of the adipose tissue-derived serpin vaspin, and our findings suggest hK7 inhibition by vaspin as an underlying physiological mechanism for its compensatory actions on obesity-induced insulin resistance. 相似文献