448 research outputs found

    Influence of vertebrae and intervertebral disc on stresses in abdominal aortic aneurysms

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    Computational modelling of stress-strain states in Abdominal Aortic Aneurysms (AAAs) has become an important tool in assessment of their rupture risk in the last decades. As its application potential in clinical practice is increasing with every additional influencing factor considered in the model, many factors have been analysed already. Up-to-date models are based on patient-specific AAA geometry obtained typically from CT-A imaging under a known level of blood pressure. Mean arterial pressure (MAP) is used to create their unloaded geometry [1] which (with other additional features such as residual stresses) may increase the credibility of the results. Material behaviour is also a very important feature to be described correctly. Large deformations of the arterial wall and intraluminal thrombus (ILT) are mostly described using constitutive models based on mean population data gathered from mechanical testing of patient-specific specimens [3]. ILT can be taken into consideration not only for his poroelastic structure reducing the blood pressure on the AAA wall but also for its significant load-bearing contribution. Different mechanical properties across the ILT thickness. Can be considered as a significant feature too. ILT with large thickness also reduces oxygen supply into the AAA wall underneath and consequently changes its mechanical properties (strength)

    Cross-sectional TEM preparation of hybrid inorganic/organic materials systems by ultramicrotomy

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    Preparation of hybrid inorganic-organic systems (HIOS) for transmission electron microscopy (TEM) in cross sectional view is the key for understanding the interfacial structure. Strikingly different materials properties like hardness, cleavability and heat sensitivity limit the number of applicable preparation strategies. Successful preparation of a HIOS system combining ZnO and para-sexiphenyl (6P) is realized by ultramicrotomy. It is shown that the alignment of the cutting plane with respect to the (0001) cleavage plane of ZnO plays a decisive role for successful preparation of extended TEM lamellae and the preservation of the HIOS structure. In particular, for (0001) oriented ZnO substrates the optimum cut direction is parallel to the HIOS interface. In cross-sectional high-resolution TEM images (100) lattice planes of 6P are observed proving the appropriate preparation strategy.Peer Reviewe

    Avaliação do modelo CANEGRO/DSSAT para quatro cultivares de cana-de-açúcar.

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    A parametrização do modelo DSSAT/CANEGRO para a realidade brasileira é de grande importância para a obtenção de uma ferramenta para o monitoramento de safras agrícolas e para a elaboração de cenários agrícolas futuros. O presente trabalho enfocou as cultivares R570, NCo376, RB72-454 e SP83-2847 nas condições de Piracicaba/SP. Os dados biométricos foram coletados no Centro de Tecnologia Canavieira, comparando-se os valores observados com as simulações para as seguintes variáveis: perfilhamento, altura de colmo, IAF, número de folhas verdes; e a fitomassa da parte aérea. O modelo apresentou resultados satisfatórios para todas as cultivares testadas, com exceção da NCo376, para a qual houve subestimativa da massa seca da parte aérea (-32%) e índice de área foliar (-13%).CBA 2009

    Prognostic and predictive value of circulating tumor cells and CXCR4 expression as biomarkers for a CXCR4 peptide antagonist in combination with carboplatin-etoposide in small cell lung cancer: exploratory analysis of a phase II study.

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    Background Circulating tumor cells (CTCs) and chemokine (C-X-C motif) receptor 4 (CXCR4) expression in CTCs and tumor tissue were evaluated as prognostic or predictive markers of CXCR4 peptide antagonist LY2510924 plus carboplatin-etoposide (CE) versus CE in extensive-stage disease small cell lung cancer (ED-SCLC). Methods This exploratory analysis of a phase II study evaluated CXCR4 expression in baseline tumor tissue and peripheral blood CTCs and in post-treatment CTCs. Optimum cutoff values were determined for CTC counts and CXCR4 expression in tumors and CTCs as predictors of survival outcome. Kaplan-Meier estimates and hazard ratios were used to determine biomarker prognostic and predictive values. Results There was weak positive correlation at baseline between CXCR4 expression in tumor tissue and CTCs. Optimum cutoff values were H-score ≥ 210 for CXCR4+ tumor, ≥7% CTCs with CXCR4 expression (CXCR4+ CTCs), and ≥6 CTCs/7.5 mL blood. Baseline H-score for CXCR4+ tumor was not prognostic of progression-free survival (PFS) or overall survival (OS). Baseline CXCR4+ CTCs ≥7% was prognostic of shorter PFS. CTCs ≥6 at baseline and cycle 2, day 1 were prognostic of shorter PFS and OS. None of the biomarkers at their respective optimum cutoffs was predictive of treatment response of LY2510924 plus CE versus CE. Conclusions In patients with ED-SCLC, baseline CXCR4 expression in tumor tissue was not prognostic of survival or predictive of LY2510924 treatment response. Baseline CXCR4+ CTCs ≥7% was prognostic of shorter PFS. CTC count ≥6 at baseline and after 1 cycle of treatment were prognostic of shorter PFS and OS

    Cytoskeletal stability and metabolic alterations in primary human macrophages in long-term microgravity

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    The immune system is one of the most affected systems of the human body during space flight. The cells of the immune system are exceptionally sensitive to microgravity. Thus, serious concerns arise, whether space flight associated weakening of the immune system ultimately precludes the expansion of human presence beyond the Earth's orbit. For human space flight, it is an urgent need to understand the cellular and molecular mechanisms by which altered gravity influences and changes the functions of immune cells. The CELLBOX-PRIME (= CellBox-Primary Human Macrophages in Microgravity Environment) experiment investigated for the first time microgravity-associated long-term alterations in primary human macrophages, one of the most important effector cells of the immune system. The experiment was conducted in the U.S. National Laboratory on board of the International Space Station ISS using the NanoRacks laboratory and Biorack type I standard CELLBOX EUE type IV containers. Upload and download were performed with the SpaceX CRS-3 and the Dragon spaceship on April 18th, 2014 / May 18th, 2014. Surprisingly, primary human macrophages exhibited neither quantitative nor structural changes of the actin and vimentin cytoskeleton after 11 days in microgravity when compared to 1g controls. Neither CD18 or CD14 surface expression were altered in microgravity, however ICAM-1 expression was reduced. The analysis of 74 metabolites in the cell culture supernatant by GC-TOF-MS, revealed eight metabolites with significantly different quantities when compared to 1g controls. In particular, the significant increase of free fucose in the cell culture supernatant was associated with a significant decrease of cell surface-bound fucose. The reduced ICAM-1 expression and the loss of cell surface-bound fucose may contribute to functional impairments, e.g. the activation of T cells, migration and activation of the innate immune response. We assume that the surprisingly small and non-significant cytoskeletal alterations represent a stable "steady state" after adaptive processes are initiated in the new microgravity environment. Due to the utmost importance of the human macrophage system for the elimination of pathogens and the clearance of apoptotic cells, its apparent robustness to a low gravity environment is crucial for human health and performance during long-term space missions

    Angiogenic gene expression and vascular density are reflected in ultrasonographic features of synovitis in early Rheumatoid Arthritis: an observational study.

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    INTRODUCTION: Neovascularization contributes to the development of sustained synovial inflammation in the early stages of Rheumatoid Arthritis. Ultrasound (US) provides an indirect method of assessing synovial blood flow and has been shown to correlate with clinical disease activity in patients with Rheumatoid Arthritis. This study examines the relationship of US determined synovitis with synovial vascularity, angiogenic/lymphangiogenic factors and cellular mediators of inflammation in a cohort of patients with early Rheumatoid Arthritis (RA) patients prior to therapeutic intervention with disease modifying therapy or corticosteroids. METHODS: An ultrasound guided synovial biopsy of the supra-patella pouch was performed in 12 patients with early RA prior to treatment. Clinical, US and biochemical assessments were undertaken prior to the procedure. Ultrasound images and histological samples were obtained from the supra-patella pouch. Histological samples were stained for Factor VIII and a-SMA (a-smooth muscle actin). Using digital imaging analysis a vascular area score was recorded. QT-PCR (quantitative-PCR) of samples provided quantification of angiogenic and lymphangiogenic gene expression and immunohistochemistry stained tissue was scored for macrophage, T cell and B cell infiltration using an existing semi-quantitative score. RESULTS: Power Doppler showed a good correlation with histological vascular area (Spearman r--0.73) and angiogenic factors such as vascular endothelial growth factor-A (VEGF-A), Angiopoietin 2 and Tie-2. In addition, lymphangiogenic factors such as VEGF-C and VEGF-R3 correlated well with US assessment of synovitis. A significant correlation was also found between power Doppler and synovial thickness, pro-inflammatory cytokines and sub-lining macrophage infiltrate. Within the supra-patella pouch there was no significant difference in US findings, gene expression or inflammatory cell infiltrate between any regions of synovium biopsied. CONCLUSION: Ultrasound assessment of synovial tissue faithfully reflects synovial vascularity. Both grey scale and power Doppler synovitis in early RA patients correlate with a pro-angiogenic and lymphangiogenic gene expression profile. In early RA both grey scale and power Doppler synovitis are associated with a pro-inflammatory cellular and cytokine profile providing considerable validity in its use as an objective assessment of synovial inflammation in clinical practice

    Unguis incarnatus – konservative oder operative Therapie?

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    Unguis incarnatus, an ingrown toenail, is a common condition in primary care, which is encountered by various medical professions. Inconsistent conservative treatment and nonindicated surgical treatment often result in complications and recurrence of the disease. Patients must be thoroughly informed about the complexity of the nail organ. This is a prerequisite to prevent trivialization of the disease and to achieve appropriate patient compliance for treatment. In this article a practical diagnostic and treatment algorithm for unguis incarnatus is presented. In mild cases of acute unguis incarnatus a consistent conservative treatment is the first-line strategy showing promising results. In cases of moderate to severe forms of acute unguis incarnatus, surgical procedures that preserve the nail matrix should be applied. For cases of chronic unguis incarnatus without an acute infection, elective partial matrixectomy can be indicated. Prior to any surgical intervention, detailed informed consent must be obtained from the patients. ZUSAMMENFASSUNG Der Unguis incarnatus ist ein häufiges Krankheitsbild, mit dem sich Patienten in der Hausarztpraxis, der dermatologischen Klinik oder der chirurgischen Notaufnahme vorstellen. Häufig führt die inkonsequente konservative Therapie oder die falsch-indizierte operative Intervention zu langwierigen und komplikationsreichen Verläufen, inklusive Rezidiven. Die Patienten sollten über die Komplexität des Nagelorgans aufgeklärt werden, um der Banalisierung der Erkrankung vorzubeugen, und eine entsprechende Compliance in der Therapie zu erreichen. In diesem Manuskript wird die sachgerechte Versorgung des Unguis incarnatus im Sinne eines praktischen Behandlungsalgorithmus dargestellt. Die konsequente konservative Therapie ist bei akutem Unguis incarnatus mit milder Ausprägung die Therapie der ersten Wahl mit guten Behandlungsergebnissen. Nagelerhaltende operative Eingriffe kommen bei moderaten/schweren akuten Formen zum Einsatz. Der chronische Unguis incarnatus, ohne floride Infektion, stellt eine elektive Operationsindikation dar. Sowohl bei den nagelerhaltenden Eingriffen als auch bei erweiterten operativen Maßnahmen ist eine chirurgische Operationsaufklärung obligat

    Slope Failure in Loess. A detailed investigation Allandale, Banks Peninsula

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    This study investigates a slope failure complex in loess at Allandale, Lyttelton Harbour. Literature relevant to the slope stability and strength of Banks Peninsula loessial soils is reviewed. Laboratory and in situ strength testing shows that both C and P layer loess in a partially saturated state displays a significant reduction in undrained shear strength with increasing degree of saturation. Strength reduction can be attributed to reduced pore water tension due to capillary suction which results from an increased degree of saturation. The moisture controlled strength component in partially saturated loess can be defined by any two of dry density, moisture content and degree of saturation. When comparing loess C and P layer remoulded strengths with peak strengths, the P layer is significantly more sensitive to remoulding than C layer. Drained direct shear testing of C layer loess produces remoulded and peak strength parameters of c'=O, Ø'=28.4° and c'=6kPa, Ø '=28.4° respectively. Drained direct shear testing of P layer loess produced remoulded and peak shear strength parameters of c'=O, Ø '=28.4° and c'=20kPa, Ø '=28.4° respectively. The slope failure complex investigated has been formed by an earthflow initiated by a tension crack in C layer loess (which acts as an unconfined leaky aquifer). Subsequent retrogressive upslope and lateral migration of the slope failure complex involves "turfmat slides" in S layer loess which also acts as an unconfined leaky aquifer, and more tension crack initiated earth flows in C layer loess. Back analysis suggests both forms of slope movement may have failed by translational sliding at the base of their respective loess layer, with a piezometric level coincident with the ground surface. Mobilisation of the "turfmat slide", requires drained remoulded shear strengths, whereas mobilisation of the earth flow is more likely to involve drained peak shear strengths
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