336 research outputs found

    FAK Is a Critical Regulator of Neuroblastoma Liver Metastasis

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    Neuroblastomas express increased levels of gastrin-releasing peptide receptor (GRP-R). However, the exact molecular mechanisms involved in GRP-R-mediated cell signaling in neuroblastoma growth and metastasis are unknown. Here, we report that focal adhesion kinase (FAK), as a critical downstream target of GRP-R, is an important regulator of neuroblastoma tumorigenicity. We found that FAK expression correlates with GRP-R expression in human neuroblastoma sections and cell lines. GRP-R overexpression in SK-N-SH cells increased FAK, integrin α3 and β1 expressions and cell migration. These cells demonstrated flatter cell morphology with broad lamellae, in which intense FAK expression was localized to the leading edges of lamellipodia. Interestingly, FAK activation was, in part, dependent on integrin α3 and β1 expression. Conversely, GRP-R silencing decreased FAK as well as Mycn levels in BE(2)-C cells, which displayed a denser cellular morphology. Importantly, rescue experiments in GRP-R silenced BE(2)-C cells showed FAK overexpression significantly enhanced cell viability and soft agar colony formation; similarly, FAK overexpression in SK-N-SH cells also resulted in increased cell growth. These effects were reversed in FAK silenced BE(2)-C cells in vitro as well as in vivo. Moreover, we evaluated the effect of FAK inhibition in vivo. FAK inhibitor (Y15) suppressed GRP-induced neuroblastoma growth and metastasis. Our results indicate that FAK is a critical downstream regulator of GRP-R, which mediates tumorigenesis and metastasis in neuroblastoma

    Patterns of Change Over Time in Knee Bone Shape Are Associated with Sex.

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    BackgroundKnee osteoarthritis (OA) is more common in females than in males; however, the biological mechanisms for the difference in sex in patients with knee OA are not well understood. Knee shape is associated with OA and with sex, but the patterns of change in the bone's shape over time and their relation to sex and OA are unknown and may help inform how sex is associated with shape and OA and whether the effect is exerted early or later in life.Questions/purposes (1) Does knee shape segregate stably into different groups of trajectories of change (groups of knees that share similar patterns of changes in bone shape over time)? (2) Do females and males have different trajectories of bone shape changes? (3) Is radiographic OA at baseline associated with trajectories of bone shape changes?MethodsWe used data collected from the NIH-funded Osteoarthritis Initiative (OAI) to evaluate a cohort of people aged 45 to 79 years at baseline who had either symptomatic knee OA or were at high risk of having it. The OAI cohort included 4796 participants (58% females; n = 2804) at baseline who either had symptomatic knee OA (defined as having radiographic tibiofemoral knee OA and answering positively to the question "have you had pain, aching or stiffness around the knee on most days for at least one month during the past 12 months") or were at high risk of symptomatic knee OA (defined as having knee symptoms during the prior 12 months along with any of the following: overweight; knee injury; knee surgery other than replacement; family history of total knee replacement for OA; presence of Heberden's nodes; daily knee bending activity) or were part of a small nonexposed subcohort. From these participants, we limited the eligible group to those with radiographs available and read at baseline, 2 years, and 4 years, and randomly selected participants from each OAI subcohort in a manner to enrich representation in the study of the progression and nonexposed subcohorts, which were smaller in number than the OA incidence subcohort. From these patients, we randomly sampled 473 knees with radiographs available at baseline, 2 years, and 4 years. We outlined the shape of the distal femur and proximal tibia on radiographs at all three timepoints using statistical shape modelling. Five modes (each mode represents a particular type of knee bone shape variation) were derived for the proximal tibia and distal femur's shape, accounting for 78% of the total variance in shape. Group-based trajectory modelling (a statistical approach to identify the clusters of participants following a similar progression of change of bone shape over time, that is, trajectory group) was used to identify distinctive patterns of change in the bone shape for each mode. We examined the association of sex and radiographic OA at baseline with the trajectories of each bone shape mode using a multivariable polytomous regression model while adjusting for age, BMI, and race.ResultsKnee bone shape change trajectories segregated stably into different groups. In all modes, three distinct trajectory groups were derived, with the mean posterior probabilities (a measure of an individual's probability of being in a particular group and often used to characterize how well the trajectory model is working to describe the population) ranging from 84% to 99%, indicating excellent model fitting. For most of the modes of both the femur and tibia, the intercepts for the three trajectory groups were different; however, the rates of change were generally similar in each mode. Females and males had different trajectories of bone shape change. For Mode 1 in the femur, females were more likely to be in trajectory Groups 3 (odds ratio 30.2 [95% CI 12.2 to 75.0]; p < 0.001) and 2 than males (OR 4.1 [95% CI 2.3 to 7.1]; p < 0.001); thus, females had increased depth of the intercondylar fossa and broader shaft width relative to epicondylar width compared with males. For Mode 1 in the tibia, females were less likely to be in trajectory Group 2 (OR 0.5 [95% CI 0.3 to 0.9]; p = 0.01) than males (that is, knees of females were less likely to display superior elevation of tibial plateau or decreased shaft width relative to head width). Radiographic OA at baseline was associated with specific shape-change trajectory groups. For Mode 1 in the femur, knees with OA were less likely to be in trajectory Groups 3 (OR 0.4 [95% CI 0.2 to 0.8]; p = 0.008) and 2 (OR 0.6 [95% CI 0.3 to 1.0]; p = 0.03) than knees without OA; thus, knees with OA had decreased depth of the intercondylar fossa and narrower shaft width relative to epicondylar width compared with knees without OA. For Mode 1 in the tibia, knees with OA were not associated with trajectory.ConclusionsThe shapes of the distal femur and proximal tibia did not change much over time. Sex and baseline knee radiographic OA status are associated with the trajectory of change in the bone's shape, suggesting that both may contribute earlier in life to the associations among trajectories observed in older individuals. Future studies might explore sex-related bone shape change earlier in life to help determine when the sex-specific shapes arise and also the degree to which these sex-related shapes are alterable by injury or other events.Level of evidenceLevel III, prognostic study

    Bridging Time Scales in Cellular Decision Making with a Stochastic Bistable Switch

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    Cellular transformations which involve a significant phenotypical change of the cell's state use bistable biochemical switches as underlying decision systems. In this work, we aim at linking cellular decisions taking place on a time scale of years to decades with the biochemical dynamics in signal transduction and gene regulation, occuring on a time scale of minutes to hours. We show that a stochastic bistable switch forms a viable biochemical mechanism to implement decision processes on long time scales. As a case study, the mechanism is applied to model the initiation of follicle growth in mammalian ovaries, where the physiological time scale of follicle pool depletion is on the order of the organism's lifespan. We construct a simple mathematical model for this process based on experimental evidence for the involved genetic mechanisms. Despite the underlying stochasticity, the proposed mechanism turns out to yield reliable behavior in large populations of cells subject to the considered decision process. Our model explains how the physiological time constant may emerge from the intrinsic stochasticity of the underlying gene regulatory network. Apart from ovarian follicles, the proposed mechanism may also be of relevance for other physiological systems where cells take binary decisions over a long time scale.Comment: 14 pages, 4 figure

    Methylome Dynamics of Bovine Gametes and in vivo Early Embryos

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    DNA methylation undergoes drastic fluctuation during early mammalian embryogenesis. The dynamics of global DNA methylation in bovine embryos, however, have mostly been studied by immunostaining. We adopted the whole genome bisulfite sequencing (WGBS) method to characterize stage-specific genome-wide DNA methylation in bovine sperm, immature oocytes, oocytes matured in vivo and in vitro, as well as in vivo developed single embryos at the 2-, 4-, 8-, and 16-cell stages. We found that the major wave of genome-wide DNA demethylation was complete by the 8-cell stage when de novo methylation became prominent. Sperm and oocytes were differentially methylated in numerous regions (DMRs), which were primarily intergenic, suggesting that these non-coding regions may play important roles in gamete specification. DMRs were also identified between in vivo and in vitro matured oocytes, suggesting environmental effects on epigenetic modifications. In addition, virtually no (less than 1.5%) DNA methylation was found in mitochondrial DNA. Finally, by using RNA-seq data generated from embryos at the same developmental stages, we revealed a weak inverse correlation between gene expression and promoter methylation. This comprehensive analysis provides insight into the critical features of the bovine embryo methylome, and serves as an important reference for embryos produced in vitro, such as by in vitro fertilization and cloning. Lastly, these data can also provide a model for the epigenetic dynamics in human early embryos

    A bifunctional ATPase drives tad pilus extension and retraction

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    A widespread class of prokaryotic motors powered by secretion motor adenosine triphosphatases (ATPases) drives the dynamic extension and retraction of extracellular fibers, such as type IV pili (T4P). Among these, the tight adherence (tad) pili are critical for surface sensing and biofilm formation. As for most other motors belonging to this class, how tad pili retract despite lacking a dedicated retraction motor ATPase has remained a mystery. Here, we find that a bifunctional pilus motor ATPase, CpaF, drives both activities through adenosine 5′-triphosphate (ATP) hydrolysis. We show that mutations within CpaF result in a correlated reduction in the rates of extension and retraction that directly scales with decreased ATP hydrolysis and retraction force. Thus, a single motor ATPase drives the bidirectional processes of pilus fiber extension and retraction

    Variation of cataract surgery costs in four different graded providers of China

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    <p>Abstract</p> <p>Background</p> <p>China has the largest population of cataract patients in the world. However, the cataract surgery rate per million remains low in China. We carried out a survey on costs of cataract surgery from four different graded providers in China and analyzed differences in cost among these clinics.</p> <p>Methods</p> <p>1,189 patients were recruited for the study in four eye clinics, located in two provinces, Guangdong province in southern China and Hubei province in central China. The average cost of each cataract surgery episode was calculated including cost of intraocular lens, cost of drugs and facility cost. We also collected information on reimbursement and disposable annual income of local residents.</p> <p>Results</p> <p>Mean total cost per cataract intervention of four different providers varied considerably, ranging from US1,293inUnionHospitaltoUS 1,293 in Union Hospital to US 536 in Jingshan County Hospital. In all providers, except for Jingshan County Hospital, the cost exceeded annual disposable income of local rural residents. As to the proportion of patients with reimbursement, the figure for Union Hospital was only 36%, while for other three clinics it was more than 60%. There was a significant difference between mean reimbursement ratios, with the highest ratio in Zhongshan Ophthalmic Center being 71%.</p> <p>Conclusions</p> <p>Significant differences in costs of cataract surgery were found among the 4 different graded providers. A part of the cost was borne by patients. Proportion of patients with reimbursement and mean reimbursement ratios were higher in economically developed regions than in economically developing regions. Much more financial support should be directed into the rural New Cooperative Medical Scheme to raise the reimbursement ratio in rural China.</p

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
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