1,040 research outputs found

    High-Resolution Patterned Cellular Constructs by Droplet-Based 3D Printing.

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    Bioprinting is an emerging technique for the fabrication of living tissues that allows cells to be arranged in predetermined three-dimensional (3D) architectures. However, to date, there are limited examples of bioprinted constructs containing multiple cell types patterned at high-resolution. Here we present a low-cost process that employs 3D printing of aqueous droplets containing mammalian cells to produce robust, patterned constructs in oil, which were reproducibly transferred to culture medium. Human embryonic kidney (HEK) cells and ovine mesenchymal stem cells (oMSCs) were printed at tissue-relevant densities (10(7) cells mL(-1)) and a high droplet resolution of 1 nL. High-resolution 3D geometries were printed with features of ≀200 μm; these included an arborised cell junction, a diagonal-plane junction and an osteochondral interface. The printed cells showed high viability (90% on average) and HEK cells within the printed structures were shown to proliferate under culture conditions. Significantly, a five-week tissue engineering study demonstrated that printed oMSCs could be differentiated down the chondrogenic lineage to generate cartilage-like structures containing type II collagen

    Existence, uniqueness and structure of second order absolute minimisers

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    Let βŠ† Rn be a bounded open C1,1 set. In this paper we prove the existence of a unique second order absolute minimiser u∞ of the functional E∞(u, O) := F(Β·, u)L∞(O), O βŠ† measurable, with prescribed boundary conditions for u and Du on βˆ‚ and under natural assumptions on F. We also show that u∞ is partially smooth and there exists a harmonic function f∞ ∈ L1() such that F(x, u∞(x)) = e∞ sgn f∞(x) for all x ∈ { f∞ = 0}, where e∞ is the infimum of the global energy

    Application of the Phenomenex EZ:faastβ„’ amino acid analysis kit for rapid gas-chromatographic determination of concentrations of plasma tryptophan and its brain uptake competitors

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    The Phenomenex EZ:faastβ„’ amino acid analysis kit is available for gas (GC) or liquid (LC) chromatographic analysis of amino acids (AA) using mass spectrometry (MS) and other GC detectors. We used it for rapid GC determination of plasma tryptophan, its brain uptake competitors (Val, Leu, Ile, Phe and Tyr) and many other amino acids. Based on solid-phase extraction, this fast method enables one person to process two plasma samples in 8–10Β min and six samples in ∼15Β min up to GC injection and a 7-min GC run per plasma sample. Using a Perkin-Elmer Clarus 500 GC, a Total Chrome software, a flame-ionisation detector (FID) and norvaline as internal standard, we used this method to analyse ∼1,000 plasma samples from normal subjects undergoing acute tryptophan depletion and loading tests. The limit of detection for most amino acids is 1Β nmol/ml (1Β ΞΌM) and in many cases less. With manual injection, coefficients of variation for the above six amino acids were 1.5–6.2% (intra-assay) and 3.8–9.7% (inter-assay). This simple, rapid and elegant method will be valuable to the amino acid analyst and researcher, as it can save much manpower time and meet urgent emergency requests and the demands of a high-throughput laboratory

    Aerobic exercise in adolescents with obesity: preliminary evaluation of a modular training program and the modified shuttle test

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    BACKGROUND: Increasing activity levels in adolescents with obesity requires the development of exercise programs that are both attractive to adolescents and easily reproducible. The aim of this study was to develop a modular aerobic training program for adolescents with severe obesity, with a focus on variety, individual targets and acquiring physical skills. We report here the effects on aerobic fitness from a pilot study. Furthermore, we examined the feasibility of the modified shuttle test (MST) as an outcome parameter for aerobic fitness in adolescents with severe obesity. METHODS: Fifteen adolescents from an inpatient body weight management program participated in the aerobic training study (age 14.7 Β± 2.1 yrs, body mass index 37.4 Β± 3.5). The subjects trained three days per week for 12 weeks, with each session lasting 30–60 minutes. The modular training program consisted of indoor, outdoor and swimming activities. Feasibility of the MST was studied by assessing construct validity, test-retest reliability and sensitivity to change. RESULTS: Comparing pretraining and end of training period showed large clinically relevant and significant improvements for all aerobic indices: e.g. VO(2 peak )17.5%, effect size (ES) 2.4; W(max )8%, ES 0.8. In addition, a significant improvement was found for the efficiency of the cardiovascular system as assessed by the oxygen pulse (15.8%, ES 1.6). Construct validity, test-retest reliability and sensitivity to change of the MST were very good. MST was significantly correlated with VO(2 peak )(r = 0.79) and W(max )(r = 0.84) but not with anthropometric measures. The MST walking distance improved significantly by 32.5%, ES 2.5. The attendance rate at the exercise sessions was excellent. CONCLUSION: This modular, varied aerobic training program has clinically relevant effects on aerobic performance in adolescents with severe obesity. The added value of our aerobic training program for body weight management programs for adolescents with severe obesity should be studied with a randomized trial. This study further demonstrated that the MST is a reliable, sensitive and easy to administer outcome measure for aerobic fitness in adolescent body weight management trials

    Glial Hsp70 Protects K+ Homeostasis in the Drosophila Brain during Repetitive Anoxic Depolarization

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    Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na+/K+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection

    Emergence of the Asian 1 Genotype of Dengue Virus Serotype 2 in Viet Nam: In Vivo Fitness Advantage and Lineage Replacement in South-East Asia

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    A better description of the extent and structure of genetic diversity in dengue virus (DENV) in endemic settings is central to its eventual control. To this end we determined the complete coding region sequence of 187 DENV-2 genomes and 68 E genes from viruses sampled from Vietnamese patients between 1995 and 2009. Strikingly, an episode of genotype replacement was observed, with Asian 1 lineage viruses entirely displacing the previously dominant Asian/American lineage viruses. This genotype replacement event also seems to have occurred within DENV-2 in Thailand and Cambodia, suggestive of a major difference in viral fitness. To determine the cause of this major evolutionary event we compared both the infectivity of the Asian 1 and Asian/American genotypes in mosquitoes and their viraemia levels in humans. Although there was little difference in infectivity in mosquitoes, we observed significantly higher plasma viraemia levels in paediatric patients infected with Asian 1 lineage viruses relative to Asian/American viruses, a phenotype that is predicted to result in a higher probability of human-to-mosquito transmission. These results provide a mechanistic basis to a marked change in the genetic structure of DENV-2 and more broadly underscore that an understanding of DENV evolutionary dynamics can inform the development of vaccines and anti-viral drugs

    Drosophila as a Model for MECP2 Gain of Function in Neurons

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    Methyl-CpG-binding protein 2 (MECP2) is a multi-functional regulator of gene expression. In humans loss of MECP2 function causes classic Rett syndrome, but gain of MECP2 function also causes mental retardation. Although mouse models provide valuable insight into Mecp2 gain and loss of function, the identification of MECP2 genetic targets and interactors remains time intensive and complicated. This study takes a step toward utilizing Drosophila as a model to identify genetic targets and cellular consequences of MECP2 gain-of function mutations in neurons, the principle cell type affected in patients with Rett-related mental retardation. We show that heterologous expression of human MECP2 in Drosophila motoneurons causes distinct defects in dendritic structure and motor behavior, as reported with MECP2 gain of function in humans and mice. Multiple lines of evidence suggest that these defects arise from specific MECP2 function. First, neurons with MECP2-induced dendrite loss show normal membrane currents. Second, dendritic phenotypes require an intact methyl-CpG-binding domain. Third, dendritic defects are amended by reducing the dose of the chromatin remodeling protein, osa, indicating that MECP2 may act via chromatin remodeling in Drosophila. MECP2-induced motoneuron dendritic defects cause specific motor behavior defects that are easy to score in genetic screening. In sum, our data show that some aspects of MECP2 function can be studied in the Drosophila model, thus expanding the repertoire of genetic reagents that can be used to unravel specific neural functions of MECP2. However, additional genes and signaling pathways identified through such approaches in Drosophila will require careful validation in the mouse model

    CEO Compensation

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    This paper surveys the recent literature on CEO compensation. The rapid rise in CEO pay over the past 30 years has sparked an intense debate about the nature of the pay-setting process. Many view the high level of CEO compensation as the result of powerful managers setting their own pay. Others interpret high pay as the result of optimal contracting in a competitive market for managerial talent. We describe and discuss the empirical evidence on the evolution of CEO pay and on the relationship between pay and firm performance since the 1930s. Our review suggests that both managerial power and competitive market forces are important determinants of CEO pay, but that neither approach is fully consistent with the available evidence. We briefly discuss promising directions for future research

    Results of NOPHO ALL2008 treatment for patients aged 1-45 years with acute lymphoblastic leukemia

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    Adults with acute lymphoblastic leukemia (ALL) do worse than children. From 7/2008 to 12/2014, Nordic and Baltic centers treated 1509 consecutive patients aged 1-45 years with Philadelphia chromosome-negative ALL according to the NOPHO ALL2008 without cranial irradiation. Overall, 1022 patients were of age 1-9 years (A), 266 were 10-17 years (B) and 221 were 18-45 years (C). Sixteen patients (three adults) died during induction. All others achieved remission after induction or 1-3 intensive blocks. Subsequently, 45 patients (12 adults) died, 122 patients relapsed (32 adults) with a median time to relapse of 1.6 years and 13 (no adult) developed a second malignancy. Median follow-up time was 4.6 years. Among the three age groups, older patients more often had higher risk ALL due to T-ALL (32%/25%/9%, PPeer reviewe
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