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981.
Pilocytic astrocytoma (PA) is the most common brain tumor in children. This tumor is usually benign and has a good prognosis. Total resection is the treatment of choice and will cure the majority of patients. However, often only partial resection is possible due to the location of the tumor. In that case, spontaneous regression, regrowth, or progression to a more aggressive form have been observed. The dependency between the residual tumor size and spontaneous regression is not understood yet. Therefore, the prognosis is largely unpredictable and there is controversy regarding the management of patients for whom complete resection cannot be achieved. Strategies span from pure observation (wait and see) to combinations of surgery, adjuvant chemotherapy, and radiotherapy. Here, we introduce a mathematical model to investigate the growth and progression behavior of PA. In particular, we propose a Markov chain model incorporating cell proliferation and death as well as mutations. Our model analysis shows that the tumor behavior after partial resection is essentially determined by a risk coefficient γ, which can be deduced from epidemiological data about PA. Our results quantitatively predict the regression probability of a partially resected benign PA given the residual tumor size and lead to the hypothesis that this dependency is linear, implying that removing any amount of tumor mass will improve prognosis. This finding stands in contrast to diffuse malignant glioma where an extent of resection threshold has been experimentally shown, below which no benefit for survival is expected. These results have important implications for future therapeutic studies in PA that should include residual tumor volume as a prognostic factor. 相似文献
982.
Jens Prescher Viola Baumg?rtel Sergey Ivanchenko Adriano A. Torrano Christoph Br?uchle Barbara Müller Don C. Lamb 《PLoS pathogens》2015,11(2)
The cellular endosomal sorting complex required for transport (ESCRT) machinery is involved in membrane budding processes, such as multivesicular biogenesis and cytokinesis. In HIV-infected cells, HIV-1 hijacks the ESCRT machinery to drive HIV release. Early in the HIV-1 assembly process, the ESCRT-I protein Tsg101 and the ESCRT-related protein ALIX are recruited to the assembly site. Further downstream, components such as the ESCRT-III proteins CHMP4 and CHMP2 form transient membrane associated lattices, which are involved in virus-host membrane fission. Although various geometries of ESCRT-III assemblies could be observed, the actual membrane constriction and fission mechanism is not fully understood. Fission might be driven from inside the HIV-1 budding neck by narrowing the membranes from the outside by larger lattices surrounding the neck, or from within the bud. Here, we use super-resolution fluorescence microscopy to elucidate the size and structure of the ESCRT components Tsg101, ALIX, CHMP4B and CHMP2A during HIV-1 budding below the diffraction limit. To avoid the deleterious effects of using fusion proteins attached to ESCRT components, we performed measurements on the endogenous protein or, in the case of CHMP4B, constructs modified with the small HA tag. Due to the transient nature of the ESCRT interactions, the fraction of HIV-1 assembly sites with colocalizing ESCRT complexes was low (1.5%-3.4%). All colocalizing ESCRT clusters exhibited closed, circular structures with an average size (full-width at half-maximum) between 45 and 60 nm or a diameter (determined using a Ripley’s L-function analysis) of roughly 60 to 100 nm. The size distributions for colocalizing clusters were narrower than for non-colocalizing clusters, and significantly smaller than the HIV-1 bud. Hence, our results support a membrane scission process driven by ESCRT protein assemblies inside a confined structure, such as the bud neck, rather than by large lattices around the neck or in the bud lumen. In the case of ALIX, a cloud of individual molecules surrounding the central clusters was often observed, which we attribute to ALIX molecules incorporated into the nascent HIV-1 Gag shell. Experiments performed using YFP-tagged Tsg101 led to an over 10-fold increase in ESCRT structures colocalizing with HIV-1 budding sites indicating an influence of the fusion protein tag on the function of the ESCRT protein. 相似文献
983.
Tetsuji Yamashita Pierre Hakizimana Siva Wu Ahmed Hassan Stefan Jacob Jamshid Temirov Jie Fang Marcia Mellado-Lagarde Richard Gursky Linda Horner Barbara Leibiger Sara Leijon Victoria E. Centonze Per-Olof Berggren Sharon Frase Manfred Auer William E. Brownell Anders Fridberger Jian Zuo 《PLoS genetics》2015,11(9)
Nature’s fastest motors are the cochlear outer hair cells (OHCs). These sensory cells use a membrane protein, Slc26a5 (prestin), to generate mechanical force at high frequencies, which is essential for explaining the exquisite hearing sensitivity of mammalian ears. Previous studies suggest that Slc26a5 continuously diffuses within the membrane, but how can a freely moving motor protein effectively convey forces critical for hearing? To provide direct evidence in OHCs for freely moving Slc26a5 molecules, we created a knockin mouse where Slc26a5 is fused with YFP. These mice and four other strains expressing fluorescently labeled membrane proteins were used to examine their lateral diffusion in the OHC lateral wall. All five proteins showed minimal diffusion, but did move after pharmacological disruption of membrane-associated structures with a cholesterol-depleting agent and salicylate. Thus, our results demonstrate that OHC lateral wall structure constrains the mobility of plasma membrane proteins and that the integrity of such membrane-associated structures are critical for Slc26a5’s active and structural roles. The structural constraint of membrane proteins may exemplify convergent evolution of cellular motors across species. Our findings also suggest a possible mechanism for disorders of cholesterol metabolism with hearing loss such as Niemann-Pick Type C diseases. 相似文献
984.
Samuel K. Asinof Stacey J. Sukoff Rizzo Alexandra R. Buckley Barbara J. Beyer Verity A. Letts Wayne N. Frankel Rebecca M. Boumil 《PLoS genetics》2015,11(6)
The childhood epileptic encephalopathies (EE’s) are seizure disorders that broadly impact development including cognitive, sensory and motor progress with severe consequences and comorbidities. Recently, mutations in DNM1 (dynamin 1) have been implicated in two EE syndromes, Lennox-Gastaut Syndrome and Infantile Spasms. Dnm1 encodes dynamin 1, a large multimeric GTPase necessary for activity-dependent membrane recycling in neurons, including synaptic vesicle endocytosis. Dnm1Ftfl or “fitful” mice carry a spontaneous mutation in the mouse ortholog of DNM1 and recapitulate many of the disease features associated with human DNM1 patients, providing a relevant disease model of human EE’s. In order to examine the cellular etiology of seizures and behavioral and neurological comorbidities, we engineered a conditional Dnm1Ftfl mouse model of DNM1 EE. Observations of Dnm1
Ftfl/flox mice in combination with various neuronal subpopulation specific cre strains demonstrate unique seizure phenotypes and clear separation of major neurobehavioral comorbidities from severe seizures associated with the germline model. This demonstration of pleiotropy suggests that treating seizures per se may not prevent severe comorbidity observed in EE associated with dynamin-1 mutations, and is likely to have implications for other genetic forms of EE. 相似文献
985.
986.
The regulation of connective tissue growth factor expression influences the viability of human trabecular meshwork cells
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Barbara M. Braunger Ernst R. Tamm Rudolf Fuchshofer 《Journal of cellular and molecular medicine》2015,19(5):1010-1020
Connective tissue growth factor (CTGF) induces extracellular matrix (ECM) synthesis and contractility in human trabecular meshwork (HTM) cells. Both processes are involved in the pathogenesis of primary open‐angle glaucoma. To date, little is known about regulation and function of CTGF expression in the trabecular meshwork (TM). Therefore, we analysed the effects of different aqueous humour proteins and stressors on CTGF expression in HTM cells. HTM cells from three different donors were treated with endothelin‐1, insulin‐like growth factor (IGF)‐1, angiotensin‐II, H2O2 and heat shock and were analysed by immunohistochemistry, real‐time RT‐PCR and Western blotting. Viability after H2O2 treatment was measured in CTGF silenced HTM‐N cells and their controls. Latrunculin A reduced expression of CTGF by about 50% compared to untreated HTM cells, whereas endothelin‐1, IGF‐1, angiotensin‐II, heat shock and oxidative stress led to a significant increase. Silencing of CTGF resulted in a delayed expression of αB‐crystallin and in reduced cell viability in comparison to the controls after oxidative stress. Conversely, CTGF treatment led to a higher cell viability rate after H2O2 treatment. CTGF expression is induced by factors that have been linked to glaucoma. An increased level of CTGF appears to protect TM cells against damage induced by stress. The beneficial effect of CTGF for viability of TM cells is likely associated with the effects on increased ECM synthesis and higher contractility of the TM, thereby contributing to reduced aqueous humour outflow facility causing increased intraocular pressure. 相似文献
987.
988.
Chiara Fini Giorgia Committeri Barbara C. N. Müller Eliane Deschrijver Marcel Brass 《PloS one》2015,10(3)
The way we experience the space around us is highly subjective. It has been shown that motion potentialities that are intrinsic to our body influence our space categorization. Furthermore, we have recently demonstrated that in the extrapersonal space, our categorization also depends on the movement potential of other agents. When we have to categorize the space as “Near” or “Far” between a reference and a target, the space categorized as “Near” is wider if the reference corresponds to a biological agent that has the potential to walk, instead of a biological and non-biological agent that cannot walk. But what exactly drives this “Near space extension”? In the present paper, we tested whether abstract beliefs about the biological nature of an agent determine how we categorize the space between the agent and an object. Participants were asked to first read a Pinocchio story and watch a correspondent video in which Pinocchio acts like a real human, in order to become more transported into the initial story. Then they had to categorize the location ("Near" or "Far") of a target object located at progressively increasing or decreasing distances from a non-biological agent (i.e., a wooden dummy) and from a biological agent (i.e., a human-like avatar). The results indicate that being transported into the Pinocchio story, induces an equal “Near” space threshold with both the avatar and the wooden dummy as reference frames. 相似文献
989.
Manfred E. Beutel Sabine Fischbeck Harald Binder Maria Blettner Elmar Br?hler Katharina Emrich Peter Friedrich-Mai Barbara H. Imruck Veronika Weyer Sylke R. Zeissig 《PloS one》2015,10(1)
Aim
The purpose of the study was to determine anxiety and depression, quality of life, and their determinants in long-term survivors of malignant melanoma.Methods
In a state cancer registry a cohort of survivors of malignant melanoma was contacted via the physician registered. Of 1302 contactable patients, 689 (52.2%) completed a questionnaire including the Patient Health Questionnaire with generalized anxiety (GAD-7) and depression (PHQ-9) and the EORTC Quality of Life Questionnaire (EORTC QLQ 30). Based on multiple regression analysis, predictors of quality of life and distress were identified. Comparison data were assessed in two waves of representative face-to-face household surveys of the adult German population.Results
An average of 8.4 (5.7 to 12.2) years after diagnosis, distress was higher in women compared to men and in middle adulthood (vs. older patients). Symptoms were higher in women than in men, and there was a decline of functioning and increase of symptoms across the age range of both genders. Compared to the general population, there were slightly increased depression and anxiety (only women), but no impaired global quality of life. Yet, survivors evidenced functional decline and more physical symptoms. Distress and reduced quality of life were consistently predicted by lack of social support, fear of recurrence, pessimism and self-blame. Distress was increased by a family history of melanoma, and additional mental and somatic diseases.Conclusion
Overall, long-term survivors have adjusted well achieving a global quality of life comparable to the general population. Yet, compromised functional dimensions, physical symptoms and distress indicate the need for integrating psychooncological screening into oncological follow-up, which might be guided by predictors such as family history or social support. Further prospective study is needed to determine the course of adaptation to the disease and corroborate the risk factors identified. 相似文献990.
Ajit G. Thomas Rita Sattler Karen Tendyke Kara A. Loiacono Hans Hansen Vishal Sahni Yutaka Hashizume Camilo Rojas Barbara S. Slusher 《PloS one》2015,10(8)
The cystine-glutamate antiporter (system xc
-) is a Na+-independent amino acid transporter that exchanges extracellular cystine for intracellular glutamate. It is thought to play a critical role in cellular redox processes through regulation of intracellular glutathione synthesis via cystine uptake. In gliomas, system xc
- expression is universally up-regulated while that of glutamate transporters down-regulated, leading to a progressive accumulation of extracellular glutamate and excitotoxic cell death of the surrounding non-tumorous tissue. Additionally, up-regulation of system xc
- in activated microglia has been implicated in the pathogenesis of several neurodegenerative disorders mediated by excess glutamate. Consequently, system xc
- is a new drug target for brain cancer and neuroinflammatory diseases associated with excess extracellular glutamate. Unfortunately no potent and selective small molecule system xc
- inhibitors exist and to our knowledge, no high throughput screening (HTS) assay has been developed to identify new scaffolds for inhibitor design. To develop such an assay, various neuronal and non-neuronal human cells were evaluated as sources of system xc
-. Human glioma cells were chosen based on their high system xc
- activity. Using these cells, [14C]-cystine uptake and cystine-induced glutamate release assays were characterized and optimized with respect to cystine and protein concentrations and time of incubation. A pilot screen of the LOPAC/NINDS libraries using glutamate release demonstrated that the logistics of the assay were in place but unfortunately, did not yield meaningful pharmacophores. A larger, HTS campaign using the 384-well cystine-induced glutamate release as primary assay and the 96-well 14C-cystine uptake as confirmatory assay is currently underway. Unexpectedly, we observed that the rate of cystine uptake was significantly faster than the rate of glutamate release in human glioma cells. This was in contrast to the same rates of cystine uptake and glutamate release previously reported in normal human fibroblast cells. 相似文献