923 research outputs found

    Establishing operando diffraction capability through the study of Li-ion (de) intercalation in LiFePO4

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    We have used a laboratory diffractometer to perform operando X-ray diffraction on LiFePO4 during electrochemical cycling in a coin cell fitted with a Kapton window. The results obtained are in good agreement with previous studies, verifying that extraction of Li from LiFePO4 follows dual-phase solid solution behaviour, with neither LiFePO4 nor FePO4 maintaining a static composition during deintercalation

    The crest phenotype in domestic chicken is caused by a 197 bp duplication in the intron of HOXC10

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    The Crest mutation in chicken shows incomplete dominance and causes a spectacular phenotype in which the small feathers normally present on the head are replaced by much larger feathers normally present only in dorsal skin. Using whole-genome sequencing, we show that the crest phenotype is caused by a 197 bp duplication of an evolutionarily conserved sequence located in the intron of HOXC10 on chromosome 33. A diagnostic test showed that the duplication was present in all 54 crested chickens representing eight breeds and absent from all 433 non-crested chickens representing 214 populations. The mutation causes ectopic expression of at least five closely linked HOXC genes, including HOXC10, in cranial skin of crested chickens. The result is consistent with the interpretation that the crest feathers are caused by an altered body region identity. The upregulated HOXC gene expression is expanded to skull tissue of Polish chickens showing a large crest often associated with cerebral hernia, but not in Silkie chickens characterized by a small crest, both homozygous for the duplication. Thus, the 197 bp duplication is required for the development of a large crest and susceptibility to cerebral hernia because only crested chicken show this malformation. However, this mutation is not sufficient to cause herniation because this malformation is not present in breeds with a small crest, like Silkie chickens

    Hmga2 deficiency is associated with allometric growth retardation, infertility, and behavioral abnormalities in mice

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    The high mobility group AT-hook 2 (HMGA2) protein works as an architectural regulator by binding AT-rich DNA sequences to induce conformational changes affecting transcription. Genomic deletions disrupting HMGA2 coding sequences and flanking noncoding sequences cause dwarfism in mice and rabbits. Here, CRISPR/Cas9 was used in mice to generate an Hmga2 null allele that specifically disrupts only the coding sequence. The loss of one or both alleles of Hmga2 resulted in reduced body size of 20% and 60%, respectively, compared to wild-type littermates as well as an allometric reduction in skull length in Hmga2(-/-) mice. Both male and female Hmga2(-/-) mice are infertile, whereas Hmga2(+/-) mice are fertile. Examination of reproductive tissues of Hmga2(-/-) males revealed a significantly reduced size of testis, epididymis, and seminal vesicle compared to controls, and 70% of knock-out males showed externalized penis, but no cryptorchidism was observed. Sperm analyses revealed severe oligospermia in mutant males and slightly decreased sperm viability, increased DNA damage but normal sperm chromatin compaction. Testis histology surprisingly revealed a normal seminiferous epithelium, despite the significant reduction in testis size. In addition, Hmga2(-/-) mice showed a significantly reduced exploratory behavior. In summary, the phenotypic effects in mouse using targeted mutagenesis confirmed that Hmga2 is affecting prenatal and postnatal growth regulation, male reproductive tissue development, and presents the first indication that Hmga2 function is required for normal mouse behavior. No specific effect, despite an allometric reduction, on craniofacial development was noted in contrast to previous reports of an altered craniofacial development in mice and rabbits carrying deletions of both coding and noncoding sequences at the 5 ' part of Hmga2

    Extracellular High-Mobility Group Box 1 is Increased in Patients with Behçet's Disease with Intestinal Involvement

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    High-mobility group box 1 (HMGB1) protein has been demonstrated to play an important role in chronic inflammatory diseases including rheumatoid arthritis, and systemic lupus erythematosus. This study investigated the association between extracellular HMGB1 expression and disease activity, and clinical features of Behçet's disease (BD). Extracellular HMGB1 expression in the sera of 42 BD patients was measured and was compared to that of 22 age- and sex-matched healthy controls. HMGB1 expression was significantly increased in BD patients compared to healthy controls (78.70 ± 20.22 vs 10.79 ± 1.90 ng/mL, P = 0.002). In addition, HMGB1 expression was significantly elevated in BD patients with intestinal involvement compared to those without (179.61 ± 67.95 vs 61.89 ± 19.81 ng/mL, P = 0.04). No significant association was observed between HMGB1 concentration and other clinical manifestations, or disease activity. It is suggested that extracellular HMGB1 may play an important role in the pathogenesis of BD

    Characteristics, management and outcome of a large necrotising otitis externa case series: need for standardised case definition

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    Background: Necrotising otitis externa (NOE) is a severe ear infection for which there are no established diagnostic or treatment guidelines. Objective: Describe clinical characteristics, management and outcomes for patients managed as NOE at a UK tertiary referral centre. Methods: Retrospective case series. Results: 58 (63%) patients were classified as definite NOE cases, 31 (34%) as probable and 3 (3%) as possible cases. Median duration of intravenous and oral antimicrobial therapy was 6.0 weeks (0.49-44.9). 6% of patients relapsed a median of 16.4 weeks (IQR 23-121) after stopping antimicrobials. 28% of cases had complex disease. These patients were older (p=0.042), had a longer duration of symptoms prior to imaging (p= 0.0001) and higher CRP at diagnosis (p=0.005). Despite longer courses of intravenous antimicrobials (23 days v 14 days; p=0.032), complex cases were more likely to relapse (p=0.016). Conclusion: A standardised case-definition of NOE is needed to optimise diagnosis, management and research

    Simulation of Bonded Joints Failure using Progressive Mixed-Mode Damage Models

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    In the most recent years, structural applications of bonded joints haveincreased remarkably owing to their several advantages relative to otherjoining methods. As a consequence, the development of improved modelsto provide design effi ciency and, at the same time, increase the confi denceof designers acquires special relevancy. Recent developments consideringcohesive and continuum mixed-mode damage models have demonstratedthat these methods are able to deal with several details inherent tomechanical behaviour of bonded joints. Both methods allow simulationof damage initiation and propagation by combining classical strength ofmaterials approaches with fracture mechanics concepts.In this work, several different mixed-mode cohesive laws adapted todifferent types of adhesives mechanical behaviour are presented and discussed.Effectively, while mechanical behaviour of brittle or moderately ductileadhesives is well simulated by means of the simple bilinear cohesivelaw, adhesives with pronounced ductile behaviour require more sophisticatedcohesive laws. The aspects regarding determination of some cohesiveparameters are also given special attention in the present paper. A continuummixed-mode damage model is also presented using the bilinear softeningcohesive law. This model is advantageous since properties degradation takesplace inside solid elements used to simulate the adhesive, which allows theevaluation of specifi c issues like the infl uence of asymmetric propagationon joint mechanical behaviour in a more realistic manner. Important conclusionsabout advantages and drawbacks of both methodologies are drawn

    Duplication of chicken defensin7 gene generated by gene conversion and homologous recombination

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    Defensins constitute an evolutionary conserved family of cationic antimicrobial peptides that play a key role in host innate immune responses to infection. Defensin genes generally reside in complex genomic regions that are prone to structural variation, and defensin genes exhibit extensive copy number variation in humans and in other species. Copy number variation of defensin genes was examined in inbred lines of Leghorn and Fayoumi chickens, and a duplication of defensin7 was discovered in the Fayoumi breed. Analysis of junction sequences confirmed the occurrence of a simple tandem duplication of defensin7 with sequence identity at the junction, suggesting nonallelic homologous recombination between defensin7 and defensin6. The duplication event generated two chimeric promoters that are best explained by gene conversion followed by homologous recombination. Expression of defensin7 was not elevated in animals with two genes despite both genes being transcribed in the tissues examined. Computational prediction of promoter regions revealed the presence of several putative transcription factor binding sites generated by the duplication event. These data provide insight into the evolution and possible function of large gene families and specifically, the defensins

    What is the role of imaging in acute low back pain?

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    In patients with non specific acute low back pain, without the red flags, a conservative approach is preferable, with assessment in 4–6 weeks. The natural history of low back pain is favorable with improvement over time, thus reassurance to such patients is very important. However, a plain radiograph or more advanced imaging techniques like MRI/CT may be ordered in back pain associated with radiculopathy or spinal stenosis and back pain associated with progressive neurologic deficits. There is limited role of imaging in non specific acute low back pain without the red flags, as the findings correlate poorly with symptoms
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