138 research outputs found

    The shape – morphing performance of magnetoactive soft materials

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    Magnetoactive soft materials (MSMs) are soft polymeric composites filled with magnetic particles that are an emerging class of smart and multifunctional materials with immense potentials to be used in various applications including but not limited to artificial muscles, soft robotics, controlled drug delivery, minimally invasive surgery, and metamaterials. Advantages of MSMs include remote contactless actuation with multiple actuation modes, high actuation strain and strain rate, self-sensing, and fast response etc. Having broad functional behaviours offered by the magnetic fillers embedded within non-magnetic matrices, MSMs are undoubtedly one of the most promising materials in applications where shape-morphing, dynamic locomotion, and reconfigurable structures are highly required. This review article provides a comprehensive picture of the MSMs focusing on the materials, manufacturing processes, programming and actuation techniques, behaviours, experimental characterisations, and device-related achievements with the current state-of-the-art and discusses future perspectives. Overall, this article not only provides a comprehensive overview of MSMs’ research and development but also functions as a systematic guideline towards the development of multifunctional, shape-morphing, and sophisticated magnetoactive devices

    Topological Evolution of Dynamical Networks: Global Criticality from Local Dynamics

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    We evolve network topology of an asymmetrically connected threshold network by a simple local rewiring rule: quiet nodes grow links, active nodes lose links. This leads to convergence of the average connectivity of the network towards the critical value Kc=2K_c =2 in the limit of large system size NN. How this principle could generate self-organization in natural complex systems is discussed for two examples: neural networks and regulatory networks in the genome.Comment: 4 pages RevTeX, 4 figures PostScript, revised versio

    Are providers prepared for genomic medicine: interpretation of Direct-to-Consumer genetic testing (DTC-GT) results and genetic self-efficacy by medical professionals

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    Background: Precision medicine is set to deliver a rich new data set of genomic information. However, the number of certified specialists in the United States is small, with only 4244 genetic counselors and 1302 clinical geneticists. We conducted a national survey of 264 medical professionals to evaluate how they interpret genetic test results, determine their confidence and self-efficacy of interpreting genetic test results with patients, and capture their opinions and experiences with direct-to-consumer genetic tests (DTC-GT). Methods: Participants were grouped into two categories, genetic specialists (genetic counselors and clinical geneticists) and medical providers (primary care, internists, physicians assistants, advanced nurse practitioners, etc.). The survey (full instrument can be found in the Additional file 1) presented three genetic test report scenarios for interpretation: a genetic risk for diabetes, genomic sequencing for symptoms report implicating a potential HMN7B: distal hereditary motor neuropathy VIIB diagnosis, and a statin-induced myopathy risk. Participants were also asked about their opinions on DTC-GT results and rank their own perceived level of preparedness to review genetic test results with patients. Results: The rates of correctly interpreting results were relatively high (74.4% for the providers compared to the specialist’s 83.4%) and age, prior genetic test consultation experience, and level of trust assigned to the reports were associated with higher correct interpretation rates. The self-selected efficacy and the level of preparedness to consult on a patient’s genetic results were higher for the specialists than the provider group. Conclusion: Specialists remain the best group to assist patients with DTC-GT, however, primary care providers may still provide accurate interpretation of test results when specialists are unavailable

    Magnetorheological brushes – Scarcely explored class of magnetic material

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    Magnetic materials such as magnetorheological (MR) fluids, and magnetorheological elastomers exhibit a broad change in their material properties, for example, viscosity and storage modulus in the presence of a magnetic field. Studies related to such MR fluid and elastomer materials are extensively available. The MR brush, meanwhile, is less frequently explored and understood. An MR brush is defined by the brush-like structures formed from chains of magnetic particles embedded within a carrier matrix, typically fluids or elastomers. In this study, we explore magnetorheological fluid (MRF) brush and magnetorheological elastomer (MRE) brush and investigate their magneto-mechanical properties. The investigation measured the stiffness and the MR response, defined as the change in properties in the presence of a magnetic field for MRF and MRE brushes. Further dependence of the magnetic effect on material and preparation parameters, mainly concentration of magnetic particles and curing flux density (for MRE brush) were investigated. The responsiveness of the brushes is compared using the Magnetorheological response index, as a proposed metric in this study. The results indicate that the MRE brush possess a greater absolute stiffness, but a lower MR response than that of the MRF brush. Both MRF and MRE brushes show an increase in the MR response with an increased concentration of magnetic fillers. MRE brush further demonstrate an enhanced MR response, which could be highly comparable to MRF brush coinciding with an increase in the magnetic flux density during the curing process. The fundamental investigation of both solid and fluid MR brushes in this study opens a new avenue in the area of magnetic materials. This new class of magnetically controllable materials could potentially be employed in applications where soft and tuneable bristle-like structures are desired

    MiR-212-3p Functions as a Tumor Suppressor Gene in Group 3 Medulloblastoma via Targeting Nuclear Factor I/B (NFIB)

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    Haploinsufficiency of chromosome 17p and c-Myc amplification distinguish group 3 medulloblastomas which are associated with early metastasis, rapid recurrence, and swift mortality. Tumor suppressor genes on this locus have not been adequately characterized. We elucidated the role of miR-212-3p in the pathophysiology of group 3 tumors. First, we learned that miR-212-3p undergoes epigenetic silencing by histone modifications in group 3 tumors. Restoring its expression reduced cancer cell proliferation, migration, colony formation, and wound healing in vitro and attenuated tumor burden and improved survival in vivo. MiR-212-3p also triggered c-Myc destabilization and degradation, leading to elevated apoptosis. We then isolated an oncogenic target of miR-212-3p, i.e. NFIB, a nuclear transcription factor implicated in metastasis and recurrence in various cancers. Increased expression of NFIB was confirmed in group 3 tumors and associated with poor survival. NFIB silencing reduced cancer cell proliferation, migration, and invasion. Concurrently, reduced medullosphere formation and stem cell markers (Nanog, Oct4, Sox2, CD133) were noted. These results substantiate the tumor-suppressive role of miR-212-3p in group 3 MB and identify a novel oncogenic target implicated in metastasis and tumor recurrence

    Inhibition of experimental autoimmune uveitis by intravitreal AAV-Equine-IL10 gene therapy

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    Equine recurrent uveitis (ERU) is a spontaneous, painful, and vision threatening disease affecting up to 25% of equine populations worldwide. Current treatments of ERU are nonspecific and have many side effects which limits them to short-term use. In order to develop an effective therapy for ERU, we investigated the use of adeno-associated virus (AAV) gene therapy, exploiting a natural immune tolerance mechanism induced by equine interleukin-10 (Equine-IL10). The purpose of this study was to evaluate the therapeutic efficacy of a single intravitreal (IVT) dose of AAV8-Equine-IL10 gene therapy for inhibition of experimental autoimmune uveitis (EAU) in rats. Each rat was dosed intravitreally (IVT) in both eyes with either balanced salt solution (BSS) (control; n = 4), AAV8-Equine-IL10 at a low dose (2.4x109 vg; n = 5) or high dose (2.4x1010 vg; n = 5). EAU was induced in all groups of rats 7 days after IVT injections and euthanized 21 days post-injection. Ophthalmic examination and aqueous humor (AH) cell counts were recorded with the observer blinded to the treatment groups. Histopathology and qPCR were performed on selected ocular tissues. Data presented herein demonstrate that AAV8-Equine-IL10 treated rats exhibited a significant decrease in clinical inflammatory scores and AH cell counts compared to BSS-treated EAU eyes on days 10, 12 and 14 post EAU induction at both administered vector doses. Mean cellular histologic infiltrative scores were also significantly less in AAV8-Equine-IL10 dosed rats compared to the BSS group. Intravitreal injection of AAV8-Equine-IL10 resulted in Equine-IL10 cDNA expression in the ciliary body, retina, cornea, and optic nerve in a dose-dependent manner. A single IVT injection of AAV8-Equine-IL10 appeared to be well-tolerated and inhibited EAU even at the lowest administered dose. These results demonstrate safety and efficacy of AAV8-Equine-IL10 to prevent EAU and support continued exploration of AAV gene therapy for the treatment of equine and perhaps human recurrent uveitis

    Neonatal resuscitation: EN-BIRTH multi-country validation study.

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    BACKGROUND: Annually, 14 million newborns require stimulation to initiate breathing at birth and 6 million require bag-mask-ventilation (BMV). Many countries have invested in facility-based neonatal resuscitation equipment and training. However, there is no consistent tracking for neonatal resuscitation coverage. METHODS: The EN-BIRTH study, in five hospitals in Bangladesh, Nepal, and Tanzania (2017-2018), collected time-stamped data for care around birth, including neonatal resuscitation. Researchers surveyed women and extracted data from routine labour ward registers. To assess accuracy, we compared gold standard observed coverage to survey-reported and register-recorded coverage, using absolute difference, validity ratios, and individual-level validation metrics (sensitivity, specificity, percent agreement). We analysed two resuscitation numerators (stimulation, BMV) and three denominators (live births and fresh stillbirths, non-crying, non-breathing). We also examined timeliness of BMV. Qualitative data were collected from health workers and data collectors regarding barriers and enablers to routine recording of resuscitation. RESULTS: Among 22,752 observed births, 5330 (23.4%) babies did not cry and 3860 (17.0%) did not breathe in the first minute after birth. 16.2% (n = 3688) of babies were stimulated and 4.4% (n = 998) received BMV. Survey-report underestimated coverage of stimulation and BMV. Four of five labour ward registers captured resuscitation numerators. Stimulation had variable accuracy (sensitivity 7.5-40.8%, specificity 66.8-99.5%), BMV accuracy was higher (sensitivity 12.4-48.4%, specificity > 93%), with small absolute differences between observed and recorded BMV. Accuracy did not vary by denominator option. < 1% of BMV was initiated within 1 min of birth. Enablers to register recording included training and data use while barriers included register design, documentation burden, and time pressure. CONCLUSIONS: Population-based surveys are unlikely to be useful for measuring resuscitation coverage given low validity of exit-survey report. Routine labour ward registers have potential to accurately capture BMV as the numerator. Measuring the true denominator for clinical need is complex; newborns may require BMV if breathing ineffectively or experiencing apnoea after initial drying/stimulation or subsequently at any time. Further denominator research is required to evaluate non-crying as a potential alternative in the context of respectful care. Measuring quality gaps, notably timely provision of resuscitation, is crucial for programme improvement and impact, but unlikely to be feasible in routine systems, requiring audits and special studies

    Loss of Dnmt3b function upregulates the tumor modifier Ment and accelerates mouse lymphomagenesis

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    DNA methyltransferase 3B (Dnmt3b) belongs to a family of enzymes responsible for methylation of cytosine residues in mammals. DNA methylation contributes to the epigenetic control of gene transcription and is deregulated in virtually all human tumors. To better understand the generation of cancer-specific methylation patterns, we genetically inactivated Dnmt3b in a mouse model of MYC-induced lymphomagenesis. Ablation of Dnmt3b function using a conditional knockout in T cells accelerated lymphomagenesis by increasing cellular proliferation, which suggests that Dnmt3b functions as a tumor suppressor. Global methylation profiling revealed numerous gene promoters as potential targets of Dnmt3b activity, the majority of which were demethylated in Dnmt3b–/– lymphomas, but not in Dnmt3b–/– pretumor thymocytes, implicating Dnmt3b in maintenance of cytosine methylation in cancer. Functional analysis identified the gene Gm128 (which we termed herein methylated in normal thymocytes [Ment]) as a target of Dnmt3b activity. We found that Ment was gradually demethylated and overexpressed during tumor progression in Dnmt3b–/– lymphomas. Similarly, MENT was overexpressed in 67% of human lymphomas, and its transcription inversely correlated with methylation and levels of DNMT3B. Importantly, knockdown of Ment inhibited growth of mouse and human cells, whereas overexpression of Ment provided Dnmt3b+/+ cells with a proliferative advantage. Our findings identify Ment as an enhancer of lymphomagenesis that contributes to the tumor suppressor function of Dnmt3b and suggest it could be a potential target for anticancer therapies

    A grammar-based distance metric enables fast and accurate clustering of large sets of 16S sequences

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    Background: We propose a sequence clustering algorithm and compare the partition quality and execution time of the proposed algorithm with those of a popular existing algorithm. The proposed clustering algorithm uses a grammar-based distance metric to determine partitioning for a set of biological sequences. The algorithm performs clustering in which new sequences are compared with cluster-representative sequences to determine membership. If comparison fails to identify a suitable cluster, a new cluster is created. Results: The performance of the proposed algorithm is validated via comparison to the popular DNA/RNA sequence clustering approach, CD-HIT-EST, and to the recently developed algorithm, UCLUST, using two different sets of 16S rDNA sequences from 2,255 genera. The proposed algorithm maintains a comparable CPU execution time with that of CD-HIT-EST which is much slower than UCLUST, and has successfully generated clusters with higher statistical accuracy than both CD-HIT-EST and UCLUST. The validation results are especially striking for large datasets. Conclusions: We introduce a fast and accurate clustering algorithm that relies on a grammar-based sequence distance. Its statistical clustering quality is validated by clustering large datasets containing 16S rDNA sequences
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