Human pluripotent stem cells (hPSC) are used to study the early stages of human development in vitro and, increasingly due to somatic cell reprogramming, cellular and molecular mechanisms of disease. ...Cell culture medium is a critical factor for hPSC to maintain pluripotency and self-renewal. Numerous defined culture media have been empirically developed but never systematically optimized for culturing hPSC. We applied design of experiments (DOE), a powerful statistical tool, to improve the medium formulation for hPSC. Using pluripotency and cell growth as read-outs, we determined the optimal concentration of both basic fibroblast growth factor (bFGF) and neuregulin-1 beta 1 (NRG1β1). The resulting formulation, named iDEAL, improved the maintenance and passage of hPSC in both normal and stressful conditions, and affected trimethylated histone 3 lysine 27 (H3K27me3) epigenetic status after genetic reprogramming. It also enhances efficient hPSC plating as single cells. Altogether, iDEAL potentially allows scalable and controllable hPSC culture routine in translational research. Our DOE strategy could also be applied to hPSC differentiation protocols, which often require numerous and complex cell culture media.
Cervical spondylomyelopathy (CSM) is a disease that affects mostly large- and giant-breed dogs. It is characterized by abnormalities of the cervical spine that may cause damage to the spinal cord and ...nerve roots. Cervical disc arthroplasty has been proposed as a treatment option in veterinary medicine. The current study evaluated the main stresses in a novel canine vertebral disc prosthesis and vertebral bodies using finite element analysis. Two experimental groups were created based on the material used for the prosthesis: stainless steel group (SSG) and titanium alloy group (TAG). Vertebral and prosthetic average equivalents von-Mises stress (VMS) and minimum principal stress (MiPS) were assessed while compressive, tensile, and lateral bending shear loads were applied. The stainless steel group had greater VMS distribution on all the evaluated parameters while the titanium alloy group had greater MiPS. Stresses were more concentrated on the lateral and ventral surfaces of the vertebral bodies than on their endplates. The average prosthetic stresses were more concentrated on the bone/implant contact surface than on the prosthesis/screw interface. Maximum stresses were concentrated in the screws’ cranial surface. The novel prosthesis allows even distribution along the vertebral body. Comparing prosthesis materials, titanium alloy was marginally superior regarding average stresses in all directions and should be less likely to suffer subsidence.
RESUMO: Espondilomielopatia cervical (EMC) é uma doença que geralmente afeta cães de raças grandes e gigantes. Ela é caracterizada por anormalidades da coluna cervical que podem causar danos à medula espinhal ou às raízes nervosas. Artroplastia cervical com prótese de disco tem sido proposta como opção de tratamento na medicina veterinária. O presente estudo teve como objetivo avaliar os principais estresses em uma nova prótese de disco intervertebral canina e corpos vertebrais por meio da análise de elementos finitos. Foram compostos dois grupos experimentais que representaram o material constituinte da nova prótese: grupos aço inoxidável (SSG) e o liga de titânio (TAG). Tensões equivalente de von-Mises (VMS) e tensão principal mínima (MiPS) média foram avaliadas sob forças de compressão, tração e torção para vértebras e prótese. O grupo SSG teve maior distribuição de VMS para todos parâmetros avaliados, enquanto o grupo TAG teve maior MiPS. Estresses estiveram mais concentrados nas superfícies lateral e ventral dos corpos vertebrais do que nas placas terminais. Os estresses médios da prótese foram mais concentrados na superfície de contato osso/implante do que na interface prótese/parafuso. Estresses máximos foram concentrados na superfície cranial do parafuso. A nova prótese permitiu distribuição uniforme do estresse ao longo do corpo vertebral. Comparando os materiais da prótese, a liga de titânio foi marginalmente superior quanto aos estresses médios em todas as direções, sendo menos provável que sofra afundamento da prótese.
Skin models are used for many applications such as research and development or grafting. Unfortunately, most lack a proper microenvironment producing poor mechanical properties and inaccurate ...extra-cellular matrix composition and organization. In this report we focused on mechanical properties, extra-cellular matrix organization and cell interactions in human skin samples reconstructed with pure collagen or dermal decellularized extra-cellular matrices (S-dECM) and compared them to native human skin. We found that Full-thickness S-dECM samples presented stiffness two times higher than collagen gel and similar to ex vivo human skin, and proved for the first time that keratinocytes also impact dermal mechanical properties. This was correlated with larger fibers in S-dECM matrices compared to collagen samples and with a differential expression of F-actin, vinculin and tenascin C between S-dECM and collagen samples. This is clear proof of the microenvironment's impact on cell behaviors and mechanical properties.
In vitro skin models have been used for a long time for clinical applications or in vitro knowledge and evaluation studies. However, most lack a proper microenvironment producing a poor combination of mechanical properties and appropriate biological outcomes, partly due to inaccurate extra-cellular matrix (ECM) composition and organization. This can lead to limited predictivity and weakness of skin substitutes after grafting. This study shows, for the first time, the importance of a complex and rich microenvironment on cell behaviors, matrix macro- and micro-organization and mechanical properties. The increased composition and organization complexity of dermal skin decellularized extra-cellular matrix populated with differentiated cells produces in vitro skin models closer to native human skin physiology.
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Cookiecutter sharks are pelagic ectoparasites that feed on pieces of flesh from large marine animals. Knowledge on these sharks is still rather scant, with the few existing works successfully using ...bites found on prey to reveal ecological patterns. This study aims to identify cookiecutter shark bite patterns on pelagic fishes in aggregated schools to gain an understanding of the ecology of these sharks. Data were collected by accompanying landings and onboard in tuna fishing vessels in the western equatorial Atlantic Ocean off Brazil. A total of 138 bite wounds were found on the bigeye tuna (
Thunnus obesus
), common dolphinfish (
Coryphaena hippurus
), skipjack tuna (
Katsuwonus pelamis
), and yellowfin tuna (
Thunnus albacares
). The most bitten species were the bigeye and yellowfin tuna, together accounting for 85% of all bites. Our findings offer novel insights into ectoparasitic ecology between cookiecutter sharks and pelagic fishes, identifying three major patterns: (i) preference of the sharks for the ventral surface of pelagic fishes; (ii) plasticity in biting tactics, with both bottom-up and lateral attacks; and (iii) habitat-dependent bite incidence (larger sharks commonly bite the skipjack tuna in epipelagic zones, whereas smaller sharks predominantly bite the bigeye tuna in mesopelagic zones). These results contribute to narrowing the gaps in knowledge on the ecology of the elusive, dwarf cookiecutter sharks. Further studies are needed for a better understanding of how shark-pelagic fish interactions are affected by the fishing of aggregated schools.
Resumo Recorrendo ao conceito de “amigo crítico”, foi realizado um estudo que teve por objetivos identificar e caracterizar a importância que é atribuída à figura do “amigo crítico” como agente ...promotor de melhoria escolar. Os dados foram recolhidos em três escolas de Educação Básica envolvidas em um projeto de autoavaliação, apoiado por um assessor externo, por meio de entrevistas semiestruturadas aos gestores e de aplicação de um questionário aos elementos das comissões de autoavaliação. A análise de conteúdo das respostas aponta para um reconhecimento da ação do “amigo crítico”, nomeadamente por trazer uma visão crítica das situações e por promover oportunidades de refletir e de debater decisões que apoiam mudanças. O estudo permitiu concluir que as assessorias desenvolvidas na lógica do “amigo crítico” podem fortalecer culturas de autoavaliação de escolas geradoras de melhorias e oportunidades de construção de comunidades de aprendizagem transformacionais.
Abstract Based on the concept of “critical friend” it was developed a study with the following objectives: identify and characterize the importance attributed to the “critical friend” as a promoter of school improvement. The data were collected in three basic education schools involved in a self-assessment project, supported by an external advisor, using semi-structured interviews with managers and questionnaires to the self-assessment committees. The answers content analysis points to a recognition of the “critical friend” action, namely by bringing a critical view and questions that promote opportunities for reflection and by debating situations that support decision making for change. The study allows to conclude that the advisement developed in a “critical friend” way can strengthen self-assessment cultures to improve schools and opportunities to develop transformational learning communities.
Resumen Utilizando el concepto de “amigo crítico” se realizó un estudio que tuvo como objetivo identificar y caracterizar la importancia que se le atribuye a la figura del “amigo crítico” como agente promotor de la mejora escolar. Los datos fueron recolectados en tres escuelas de Educación Básica involucradas en un proyecto de autoevaluación, apoyado por un asesor externo, a través de entrevistas semiestructuradas con gestores y con la aplicación de un cuestionario a los miembros de las comisiones de autoevaluación. El análisis de contenido de las respuestas apunta a un reconocimiento de la acción del “amigo crítico”, es decir, para traer una visión crítica de las situaciones y para promover oportunidades para reflexionar y debatir decisiones que apoyen los cambios. El estudio permitió concluir que las consultorías desarrolladas en la lógica del “amigo crítico” pueden fortalecer culturas de autoevaluación en las escuelas que generan mejoras y oportunidades para construir comunidades de aprendizaje transformacionales.
hair follicle (HF) models are currently limited to
HF organ cultures (HFOCs) or 2D models that are of low availability and do not reproduce the architecture or behavior of the hair, leading to poor ...screening systems. To resolve this issue, we developed a technology for the construction of a human
hair construct based on the assemblage of different types of cells present in the hair organ. First, we demonstrated that epithelial cells, when isolated
, have similar genetic signatures regardless of their dissection site, and their trichogenic potential is dependent on the culture conditions. Then, using cell aggregation techniques, 3D spheres of dermal papilla (DP) were constructed, and subsequently, epithelial cells were added, enabling the production and organization of keratins in hair, similar to what is seen
. These reconstructed tissues resulted in the following hair compartments: K71 (inner root-sheath), K85 (matrix region), K75 (companion layer), and vimentin (DP). Furthermore, the new hair model was able to elongate similarly to
HFOC, resulting in a shaft-like shape several hundred micrometers in length. As expected, when the model was exposed to hair growth enhancers, such as ginseng extract, or inhibitors, such as TGF-B-1, significant effects similar to those
were observed. Moreover, when transplanted into skin biopsies, the new constructs showed signs of integration and hair bud generation. Owing to its simplicity and scalability, this model fully enables high throughput screening of molecules, which allows understanding of the mechanism by which new actives treat hair loss, finding optimal concentrations, and determining the synergy and antagonism among different raw materials. Therefore, this model could be a starting point for applying regenerative medicine approaches to treat hair loss.
Atopic dermatitis (AD) is a chronic inflammatory skin disease that is not fully understood. Defects in skin barrier function and dysregulation of the Th2 immune response are thought to be pivotal in ...AD pathogenesis. In this study, we used keratinocytes and AD-like skin equivalent models using Th2 cytokines IL-4 and IL-13. The keratinocytes and AD-like skin model were used to investigate the effect of dipotassium glycyrrhizinate (KG), which is widely used as an anti-inflammatory agent for AD treatment. KG decreased AD-related gene expression in keratinocytes stimulated with Th2 cytokines. KG alleviated AD-like phenotypes and gene expression patterns and inhibited release of AD-related cytokines in the AD-like skin equivalent models. These findings indicate KG has potential effectiveness in AD treatment and AD-like skin equivalent models may be useful for understanding AD pathogenesis.
Spinal metastasis with spinal cord involvement is a frequent complication in cancer patients. As the spinal compression frequently occurs ventrally, performing a simple posterior laminectomy alone is ...generally ineffective and dangerous. Many aggressive surgical strategies have been developed to improve outcomes for patients with metastatic spine disease. These strategies are associated with high morbidity and complication rates, especially in patients with numerous neoplasm-associated comorbidities, which can limit their indication in patients with a limited life expectancy. The authors performed a prospective evaluation of minimally invasive decompression and stabilization for the palliative management of symptomatic thoracolumbar spine metastasis.
Ten patients with metastasis to the thoracolumbar spine and neurological compromise underwent minimally invasive transpedicular vertebrectomy and spinal cord decompression through a tubular expandable retractor. Percutaneous stabilization was also systematically performed to ensure spinal stability.
No complications during the procedure were reported. The mean operative duration was 170 minutes and the mean estimated blood loss was 400 ml. The postoperative course of all patients was uneventful, with the exception of 1 benign urinary tract infection. Eight patients (80%) improved at least 1 Frankel grade.
Minimally invasive treatment of thoracolumbar spine metastasis is a safe and effective palliative option in patients with limited life expectancy, to limit morbidity and preserve quality of life.
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