How myosin VI traps its off-state, is activated and dimerizes.

Myosin VI (Myo6) is the only minus-end directed nanomotor on actin, allowing it to uniquely contribute to numerous cellular functions. As for other nanomotors, the proper functioning of Myo6 relies on precise spatiotemporal control of motor activity via a poorly defined off-state and interactions with partners. Our structural, functional, and cellular studies reveal key features of myosin regulation and indicate that not all partners can activate Myo6. TOM1 and Dab2 cannot bind the off-state, while GIPC1 binds Myo6, releases its auto-inhibition and triggers proximal dimerization. Myo6 partners thus differentially recruit Myo6. We solved a crystal structure of the proximal dimerization domain, and show that its disruption compromises endocytosis in HeLa cells, emphasizing the importance of Myo6 dimerization. Finally, we show that the L926Q deafness mutation disrupts Myo6 auto-inhibition and indirectly impairs proximal dimerization. Our study thus demonstrates the importance of partners in the control of Myo6 auto-inhibition, localization, and activation.

Transcending the amyloid-beta dominance paradigm in Alzheimer's disease: An exploration of behavioural, metabolic, and gut microbiota phenotypes in 5xFAD mice.

The amyloid cascade hypothesis is widely accepted as an explanation for the neuropathological changes in Alzheimer's disease (AD). However, the role of amyloid-beta (Aß) as the sole cause of these changes is being questioned. Using the 5xFAD mouse model of AD, we investigated various factors contributing to neuropathology, including genetic load (heterozygous (HTZ) versus homozygous (HZ) condition), behavioural phenotype, neuropathology markers, metabolic physiology, and gut microbiota composition at early (5 months of age) and late (12 months of age) stages of disease onset, and considering both sexes. At 5 months of age, both HTZ and HZ mice exhibited hippocampal alterations associated with Aß accumulation, leading to increased neuroinflammation and disrupted PI3K-Akt pathway. However, only HZ mice showed cognitive impairment in the Y-maze and Morris water maze tests, worsening with age. Dysregulation of both insulin and insulin secretion-regulating GIP peptide were observed at 5 months of age, disappearing later. Circulating levels of metabolic-regulating hormones, such as Ghrelin and resisting helped to differentiates HTZ mice from HZ mice. Differences between HTZ and HZ mice were also observed in gut microbiota composition, disrupted intestinal barrier proteins, and increased proinflammatory products in the intestine. These findings suggest that cognitive impairment in 5xFAD mice may not solely result from Aß aggregation. Other factors, including altered PI3K-Akt signalling, disrupted insulin-linked metabolic pathways, and changes in gut microbiota, contribute to disease progression. Targeting Aß deposition alone may not suffice. Understanding AD pathogenesis and its multiple contributing factors is vital for effective therapies.

Cursos online sobre aleitamento materno como estratégia para melhoria da qualidade assistencial: revisão de escopo / Online courses on breastfeeding as a strategy to improve the quality of care: a scoping review / Cursos en línea sobre lactancia materna como estrategia para mejorar la calidad de la atención: una revisión de alcance

Objetivo: analisar a produção científica sobre cursos online sobre aleitamento materno como estratégia para melhoria da qualidade assistencial. Métodos: Revisão de escopo, baseada no método proposto pelo Joanna Briggs Institute.As bases eletrônicas de dados utilizadas foram: PubMed; LILACS; CINAHL; SCOPUS; Web of Science; BDENF e EMBASE, publicados de 2015 a 2020. Resultados: De um total de 961 resumos, 15 artigos foram selecionados e lidos na íntegra, com inclusão de 9. As publicações ocorreram entre 2011 e 2020, com amostras entre 54 a 26.009 participantes. Em apenas 5 estudos (55,6%) utilizou-se algum método de avaliação da aprendizagem e a estratégia mais usada foi a aplicação de pré e pós teste. Conclusão: A escassez de estudos a respeito de cursos online sobre aleitamento materno para melhoria da qualidade assistencial evidencia uma lacuna de conhecimento sobre o tema. Também se constatou a necessidade de melhorar a descrição metodológica dos estudos publicados.

Objective: to analyze the scientific production on online courses on breastfeeding as a strategy to improve the quality of care.Methods: a scoping review, based on the method proposed by the Joanna Briggs Institute.The electronic databases used were: PubMed; LILACS; CINAHL; SCOPUS; Web of Science; BDENF and EMBASE, published from 2015 to 2020. Results: 961 abstracts were read, 15 articles in full for the final inclusion of 9 articles. The publications occurred between 2011 and 2020, their samples ranged from 54 to 26009 participants. In only 5 studies (55.6%) some method of learning assessment was used and the most used strategy was the application of pre and post test. Conclusion: the scarcity of studies on online courses on breastfeeding as a strategy to improve the quality of care shows a gap in knowledge on the subject. It was also found the need to improve the methodological description of the published studies.

Objetivo: analizar la producción científica sobre cursos online en aleatoriedad materna como estrategia para mejorar la calidad asistencial. Métodos: Revisión de escopo, basada en el método propuesto por el Instituto Joanna Briggs.Las bases de datos electrónicas utilizadas fueron: PubMed; LILACS; CINAHL; SCOPUS; Web of Science; BDENF y EMBASE, publicadas desde 2015 hasta 2020. Resultados: Se leyeron 961 resúmenes, 15 artículos completos para la inclusión final de 9 artículos. Las publicaciones se produjeron entre 2011 y 2020, sus muestras oscilaron entre 54 y 26009 participantes. Sólo en 5 estudios (55,6%) se utilizó algún método de evaluación del aprendizaje y la estrategia más utilizada fue la aplicación de pre y postest. Conclusión: La escasez de estudios a propósito de los cursos online sobre el aleitamento materno como estrategia para la mejora de la calidad asistencial evidencia una laguna de conocimiento sobre el tema. También se constató la necesidad de mejorar la descripción metodológica de los estudios publicados.

ER membrane contact sites support endosomal small GTPase conversion for exosome secretion.

Exosomes are endosome-derived extracellular vesicles involved in intercellular communication. They are generated as intraluminal vesicles within endosomal compartments that fuse with the plasma membrane (PM). The molecular events that generate secretory endosomes and lead to the release of exosomes are not well understood. We identified a subclass of non-proteolytic endosomes at prelysosomal stage as the compartment of origin of CD63 positive exosomes. These compartments undergo a Rab7a/Arl8b/Rab27a GTPase cascade to fuse with the PM. Dynamic endoplasmic reticulum (ER)-late endosome (LE) membrane contact sites (MCS) through ORP1L have the distinct capacity to modulate this process by affecting LE motility, maturation state, and small GTPase association. Thus, exosome secretion is a multi-step process regulated by GTPase switching and MCS, highlighting the ER as a new player in exosome-mediated intercellular communication.

Fecal calprotectin as a biomarker of microscopic bowel inflammation in patients with spondyloarthritis.

AIM: Microscopic bowel inflammation is present in up to 60% of all patients with spondyloarthritis (SpA) and appears to be associated with more severe joint disease and a higher risk of developing inflammatory bowel disease (IBD). This study aimed to determine the utility of fecal calprotectin (fCAL) in evaluating endoscopic and histological bowel inflammation in SpA patients. METHODS: Ileocolonoscopies with biopsies and fCAL measurements were performed in 65 patients with SpA. RESULTS: In 47 (72.3%) patients, the fCAL levels were higher than 50 µg/g, whereas in 20 (30.7%), these levels were greater than 250 µg/g. A total of 38 (58.5%) patients presented with microscopic bowel inflammation, and 13 (20%) presented with signs of endoscopic inflammation. fCAL levels were significantly higher in patients with microscopic bowel inflammation than in those without inflammatory findings (P < .001); additionally, these levels were slightly higher in patients with endoscopic signs of bowel inflammation (P = .053). A fCAL cutoff value of 96 µg/g predicted histological bowel inflammation with 73% sensitivity and 67% specificity. No statistically significant difference was observed in the fCAL levels between patients who had been treated or not treated with nonsteroidal anti-inflammatory drugs (NSAIDs). CONCLUSION: Our findings confirm a high prevalence of microscopic bowel inflammation in SpA patients, regardless of the use of NSAIDs. The evaluation of fCAL levels proved to be useful in the identification of microscopic inflammation and could help in the more judicious indication of ileocolonoscopy. These results support the use of fCAL for the evaluation of microscopic bowel inflammation in SpA patients.

The impact of ion chamber components onkB,Qfor reference dosimetry in MRgRT.

For reference dosimetry in MRgRT,kB,Qis used to correct for the impact of the magnetic field on the chamber calibration coefficient. It has been demonstrated that for accurate simulation ofkB,Qthe dead volume (DV) must be considered. This work goes one step further by analysing the contribution of secondary electrons generated in the various chamber components tokB,Q. The Farmer-type chamber PTW 30013 geometry was modelled for two different DVs. Monte Carlo simulations were performed for a60Co source and a 7 MV MRI-linac and the model was validated against measurements. Both parallel (α = 0° or 180°) and perpendicular (α = 90° or 270°) orientations of the chamber and the magnetic (B) field were considered, and severalB-field strengths between 0 T and 1.5 T. To study the dose contribution to the reduced volume (RV = cavity - DV) from the secondary electrons produced in certain components of the chamber the labelling of the particles was implemented in the PENELOPE user code PENMAIN. A separate model with each solid component of the chamber modelled as liquid water was used to investigate the impact of material choice onkB,Q. Results show that simulatedkB,Qvalues agree better with the measuredkB,Qwhen the DV is considered. It is demonstrated that small components of the chamber impactkB,Qconsiderably, since the contribution to the RV-dose from the bodies closer to the RV is higher than withoutB. Moreover, it is seen that the impact to the dose in the RV is reduced when the material of each component is modelled as liquid water. Therefore, chamber design and, to a lesser extent, choice of material affectkB,Q, and an accurate geometrical model of the chamber components and its further validation are important for correct calculations ofkB,Q.

Impact of the Timing and Use of an Insecticide on Arthropods in Cover-Crop-Corn Systems.

Cover crops provide a habitat for pests and beneficial arthropods. Unexpected pest pressure in a cover-crop-to-corn system can occur and result in increased use of insecticides. Eight site-years of on-farm field studies were conducted in 2019, 2020, and 2021. The objective of the study was to evaluate the impact of insecticide timing relative to cover-crop termination on arthropod activity in a cover-crop-to-corn system. The treatments consisted of (i) glyphosate to terminate the cover crop, (ii) glyphosate and pyrethroid tank mix to terminate the cover crop, and (iii) glyphosate to terminate the cover crop and pyrethroid application 25 days after the termination. Arthropod activity was measured with pitfall traps before and at each treatment application. A total of 33,316 arthropods were collected. Total arthropods, Collembola, and Aphididae were the only taxa reduced with an insecticide application. The other arthropod taxa were mainly influenced by the sampling period. No significant pest pressure occurred at any site-year. Insecticide applications are not generally needed in a cover-crop-to-corn system. Scouting for pests and applying strategies only when necessary is crucial to conserve potentially beneficial arthropods in the system.

Mahogunin Ring Finger 1 regulates pigmentation by controlling the pH of melanosomes in melanocytes and melanoma cells.

Mahogunin Ring Finger 1 (MGRN1) is an E3-ubiquitin ligase absent in dark-furred mahoganoid mice. We investigated the mechanisms of hyperpigmentation in Mgrn1-null melan-md1 melanocytes, Mgrn1-KO cells obtained by CRISPR-Cas9-mediated knockdown of Mgrn1 in melan-a6 melanocytes, and melan-a6 cells depleted of MGRN1 by siRNA treatment. Mgrn1-deficient melanocytes showed higher melanin content associated with increased melanosome abundance and higher fraction of melanosomes in highly melanized maturation stages III-IV. Expression, post-translational processing and enzymatic activity of the rate-limiting melanogenic enzyme tyrosinase measured in cell-free extracts were comparable in control and MGRN1-depleted cells. However, tyrosinase activity measured in situ in live cells and expression of genes associated with regulation of pH increased upon MGRN1 repression. Using pH-sensitive fluorescent probes, we found that downregulation of MGRN1 expression in melanocytes and melanoma cells increased the pH of acidic organelles, including melanosomes, strongly suggesting a previously unknown role of MGRN1 in the regulation of melanosomal pH. Among the pH regulatory genes upregulated by Mgrn1 knockdown, we identified those encoding several subunits of the vacuolar adenosine triphosphatase V-ATPase (mostly Atp6v0d2) and a calcium channel of the transient receptor potential channel family, Mucolipin 3 (Mcoln3). Manipulation of expression of the Mcoln3 gene showed that overexpression of Mcoln3 played a significant role in neutralization of the pH of acidic organelles and activation of tyrosinase in MGRN1-depleted cells. Therefore, lack of MGRN1 led to cell-autonomous stimulation of pigment production in melanocytes mostly by increasing tyrosinase specific activity through neutralization of the melanosomal pH in a MCOLN3-dependent manner.

Exercise Training Improved Pulmonary Gas Exchange Abnormalities in Pulmonary Hypertension due to Heart Failure: A Case Report

Abstract Heart failure (HF) is the most common cause of pulmonary hypertension (PH), and reduced exercise capacity and exertional dyspnea are the most frequent concerns in patients with PH-HF. Indeed, carbon dioxide end-tidal partial pressure (PETCO 2 ) during exercise is a well-established noninvasive marker of ventilation/perfusion ratio in PH. We aimed to evaluate the effect of aerobic exercise training on PETCO 2 response during exercise in a 59-year-old woman with PH secondary to idiopathic dilated cardiomyopathy. The patient with chronic fatigue and dyspnea at mild-to-moderate efforts was admitted to a cardiorespiratory rehabilitation program and had her cardiorespiratory response to exercise assessed during a cardiopulmonary exercise testing performed before and after three months of a thrice-weekly aerobic exercise training program. Improvements in aerobic capacity (23.9%) and endurance time (37.5%) and reduction in ventilatory inefficiency (-20.2%) was found after intervention. Post-intervention improvements in PETCO 2 at ventilatory anaerobic threshold (23.3%) and change in PETCO 2 kinetics pattern, with progressive increases from rest to peak of exercise, were also found. Patient also improved breathing pattern and timing of ventilation. This case report demonstrated for the first time that aerobic exercise training might be able to improve PETCO 2 response during exercise in a patient with PH-HF.

Real-world treatment patterns and disease control over one year in patients with inflammatory bowel disease in Brazil.

BACKGROUND: Crohn's disease (CD) and ulcerative colitis (UC) are inflammatory bowel diseases (IBDs) with a remission-relapsing presentation and symptomatic exacerbations that have detrimental impacts on patient quality of life and are associated with a high cost burden, especially in patients with moderate-to-severe disease. The Real-world Data of Moderate-to-Severe Inflammatory Bowel Disease in Brazil (RISE BR) study was a noninterventional study designed to evaluate disease control, treatment patterns, disease burden and health-related quality of life in patients with moderate-to-severe active IBD. We report findings from the prospective follow-up phase of the RISE BR study in patients with active UC or CD. AIM: To describe the 12-mo disease evolution and treatment patterns among patients with active moderate-to-severe IBD in Brazil. METHODS: This was a prospective, noninterventional study of adult patients with active Crohn's disease (CD: Harvey-Bradshaw Index ≥ 8, CD Activity Index ≥ 220), inadequate CD control (i.e., calprotectin > 200 µg/g or colonoscopy previous results), or active ulcerative colitis (UC: Partial Mayo score ≥ 5). Enrollment occurred in 14 centers from October 2016 to February 2017. The proportion of active IBD patients after 9-12 mo of follow-up, Kaplan-Meier estimates of the time to mild or no activity and a summary of treatment initiation, discontinuation and dose changes were examined. RESULTS: The study included 118 CD and 36 UC patients, with mean ± SD ages of 43.3 ± 12.6 and 44.9 ± 16.5 years, respectively. The most frequent drug classes at index were biologics for CD (62.7%) and 5-aminosalicylate derivates for UC patients (91.7%). During follow-up, 65.3% of CD and 86.1% of UC patients initiated a new treatment at least once. Discontinuations/dose changes occurred in 68.1% of CD patients [median 2.0 (IQR: 2-5)] and 94.3% of UC patients [median 4.0 (IQR: 3-7)]. On average, CD and UC patients had 4.4 ± 2.6 and 5.0 ± 3.3 outpatient visits, respectively. The median time to first mild or no activity was 319 (IQR: 239-358) d for CD and 320 (IQR: 288-358) d for UC patients. At 9-12 mo, 22.0% of CD and 20.0% of UC patients had active disease. CONCLUSION: Although a marked proportion of active IBD patients achieved disease control within one year, the considerable time to achieve this outcome represents an unmet medical need of the current standard of care in a Brazilian real-world setting.

Melanosome Biogenesis in the Pigmentation of Mammalian Skin.

Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and function are determined by a cohort of resident transmembrane proteins, many of which are expressed only in pigment cells and localize specifically to melanosomes. Defects in the genes that encode melanosome-specific proteins or components of the machinery required for their transport in and out of melanosomes underlie various forms of ocular or oculocutaneous albinism, characterized by hypopigmentation of the hair, skin, and eyes and by visual impairment. We review major components of melanosomes, including the enzymes that catalyze steps in melanin synthesis from tyrosine precursors, solute transporters that allow these enzymes to function, and structural proteins that underlie melanosome shape and melanin deposition. We then review the molecular mechanisms by which these components are biosynthetically delivered to newly forming melanosomes-many of which are shared by other cell types that generate cell type-specific lysosome-related organelles. We also highlight unanswered questions that need to be addressed by future investigation.

Implementation of care for the use of the extracorporeal oxygenation membrane in the COVID-19 pandemic.

OBJECTIVE: To report the experience of a quaternary care center on the implementation of a care program for patients with severe hypoxemic respiratory failure due to SARS-CoV-2 requiring an extracorporeal oxygenation membrane. METHOD: This is an experience report with a descriptive approach, analyzing the use of the extracorporeal oxygenation membrane in a quaternary care center in the city of Rio de Janeiro. RESULTS: The planning for the use of the extracorporeal oxygenation membrane included training with the professionals and use of the components related to the adaptation of the protocol, equipment, facilities, quality and safety. FINAL CONSIDERATIONS: Planning, resource allocation and regular training of the team to offer complex interventions, in line with recommendations for good practices in the care for patients with pulmonary complications related to the new coronavirus were essential for the development of the action plan for the use of extracorporeal oxygenation membrane in this pandemic period.

Implementation of care for the use of the extracorporeal oxygenation membrane in the COVID-19 pandemic / Implantación de cuidados para el uso de la membrana de oxigenación extracorpórea durante la pandemia por COVID-19 / Implementação de cuidados para uso de membrana de oxigenação extracorpórea na pandemia por COVID-19

ABSTRACT Objective: To report the experience of a quaternary care center on the implementation of a care program for patients with severe hypoxemic respiratory failure due to SARS-CoV-2 requiring an extracorporeal oxygenation membrane. Method: This is an experience report with a descriptive approach, analyzing the use of the extracorporeal oxygenation membrane in a quaternary care center in the city of Rio de Janeiro. Results: The planning for the use of the extracorporeal oxygenation membrane included training with the professionals and use of the components related to the adaptation of the protocol, equipment, facilities, quality and safety. Final Considerations: Planning, resource allocation and regular training of the team to offer complex interventions, in line with recommendations for good practices in the care for patients with pulmonary complications related to the new coronavirus were essential for the development of the action plan for the use of extracorporeal oxygenation membrane in this pandemic period.

RESUMEN Objetivo: Reportar sobre la experiencia de un centro cuaternario sobre la implantación de un programa de cuidados a pacientes con insuficiencia respiratoria hipoxémica grave por SARS-CoV-2, con necesidad de membrana de oxigenación extracorpórea. Método Se trata de un reporte de experiencia, con enfoque descriptivo, sobre la utilización de la membrana de oxigenación extracorpórea en un centro cuaternario de la ciudad de Río de Janeiro. Resultados: En la planificación para la utilización de la membrana de oxigenación extracorpórea, los profesionales recibieron capacitación respecto a los componentes relacionados con la adecuación del protocolo, equipos, instalaciones, calidad y seguridad. Consideraciones Finales: La planificación, asignación de recursos y mantenimiento de la capacitación regular del personal para realizar intervenciones complejas de acuerdo con las recomendaciones de buenas prácticas en la atención de pacientes con complicaciones pulmonares relacionadas con el nuevo coronavirus, fueron pilares fundamentales para el desarrollo del plan de acción para el uso de la membrana de oxigenación extracorpórea en este período pandémico.

RESUMO Objetivo: Relatar a experiência de um centro quaternário sobre a implementação de um programa de cuidados a pacientes com insuficiência respiratória hipoxêmica grave por SARS-CoV-2 com necessidade de membrana de oxigenação extracorpórea. Método: Trata-se de um relato de experiência, com abordagem descritiva, para utilização da membrana de oxigenação extracorpórea em um centro quaternário na cidade do Rio de Janeiro. Resultados: No planejamento para utilização da membrana de oxigenação extracorpórea, foram realizados treinamentos com os profissionais, utilizados os componentes relacionados a adequação do protocolo, equipamentos, instalações, qualidade e segurança. Considerações Finais: Planejamento, alocação de recursos e manutenção de treinamentos regulares com a equipe, para oferecer intervenções complexas, alinhadas com as recomendações para boas práticas no cuidado aos pacientes com complicações pulmonares relacionadas ao novo coronavírus, foram pilares fundamentais para o desenvolvimento do plano de ação na utilização da membrana de oxigenação extracorpórea neste período de pandemia.

Endoscopic clipping for gastrointestinal bleeding: emergency and prophylactic indications.

Endoscopic clipping has become a common practice among endoscopists. Several models are available, most frequently being introduced via the working channel of the endoscope (through-the-scope); however, larger clips can also be mounted onto the distal tip of the endoscope (over-the-scope). The main indications for endoclip placement include providing effective mechanical hemostasis for bleeding lesions and allowing endoscopic closure of gastrointestinal perforations. Endoclips can also be used prophylactically after endoscopic resection; however, this practice is still controversial. This review discusses the main indications for endoscopic clipping in the esophagus, stomach, duodenum and colon to manage acute bleeding lesions, and the criteria to be used in the prevention of delayed post-polypectomy bleeding.

Mahogunin Ring Finger 1 Is Required for Genomic Stability and Modulates the Malignant Phenotype of Melanoma Cells.

The mouse mahoganoid mutation abrogating Mahogunin Ring Finger-1 (MGRN1) E3 ubiquitin ligase expression causes hyperpigmentation, congenital heart defects and neurodegeneration. To study the pathophysiology of MGRN1 loss, we compared Mgrn1-knockout melanocytes with genetically matched controls and melan-md1 (mahoganoid) melanocytes. MGRN1 knockout induced a more differentiated and adherent phenotype, decreased motility, increased the percentage of cells in the S phase of the cell cycle and promoted genomic instability, as shown by stronger γH2AX labelling, increased burden of DNA breaks and higher abundance of aneuploid cells. Lack of MGRN1 expression decreased the ability of melanocytes to cope with DNA breaks generated by oxidizing agents or hydroxyurea-induced replicative stress, suggesting a contribution of genomic instability to the mahoganoid phenotype. MGRN1 knockout in B16-F10 melanoma cells also augmented pigmentation, increased cell adhesion to collagen, impaired 2D and 3D motility and caused genomic instability. Tumors formed by Mgrn1-KO B16-F10 cells had lower mitotic indices, fewer Ki67-positive cells and showed a trend towards smaller size. In short-term lung colonization assays Mgrn1-KO cells showed impaired colonization potential. Moreover, lower expression of MGRN1 is significantly associated with better survival of human melanoma patients. Therefore, MGRN1 might be an important phenotypic determinant of melanoma cells.

Coupling of melanocyte signaling and mechanics by caveolae is required for human skin pigmentation.

Tissue homeostasis requires regulation of cell-cell communication, which relies on signaling molecules and cell contacts. In skin epidermis, keratinocytes secrete factors transduced by melanocytes into signaling cues promoting their pigmentation and dendrite outgrowth, while melanocytes transfer melanin pigments to keratinocytes to convey skin photoprotection. How epidermal cells integrate these functions remains poorly characterized. Here, we show that caveolae are asymmetrically distributed in melanocytes and particularly abundant at the melanocyte-keratinocyte interface in epidermis. Caveolae in melanocytes are modulated by ultraviolet radiations and keratinocytes-released factors, like miRNAs. Preventing caveolae formation in melanocytes increases melanin pigment synthesis through upregulation of cAMP signaling and decreases cell protrusions, cell-cell contacts, pigment transfer and epidermis pigmentation. Altogether, we identify that caveolae serve as molecular hubs that couple signaling outputs from keratinocytes to mechanical plasticity of pigment cells. The coordination of intercellular communication and contacts by caveolae is thus crucial to skin pigmentation and tissue homeostasis.

Roughness and stability of compound resin color exposed to bleaching strips after surface treatment / Rugosidade e estabilidade de cor após clareamento caseiro

ABSTRACT Objective to analyze the surface roughness and color stability of the composite resin after surface treatment with the aluminum oxide discs and subsequent exposure to the Advanced Teeth Whitening Strips. Methods 20 specimens of the Filtek Z350XT restorer (3M®) were prepared and daily subjected to home bleaching for 30 minutes during 14 days. A precision rugosimeter was used in order to verify the roughness by means of 3 random readings in the same direction in each sample. For color stability the CIELAB system (L*, a*, b* values) was used through the spectrophotometer (MINOLTA CR -321, Japan). The means of the test specimens as well as the mean of each group were calculated using the random readings. Data statistical analysis were performed by ANOVA- analysis of variance. The level of significance was set at 5% (p ≤ 0.05). Results Roughness did not present great numerical variations. No statistically significant difference between the means obtained concerning the surface roughness of the composite resin with p = 0.44 was observed. However, it was found that there was a statistically significant difference between the means obtained in relation to the color stability of the composite resin, p=0. 007. Conclusion It was concluded that pre-contoured strips containing 6% hydrogen peroxide do not have a significant adverse effect on the roughness of Z350XT (3M®) resin. However, it was also concluded that according to the color stability analysis performed, there may be an indication of the restoration replacement after the bleaching treatment, due to their color change.

RESUMO Objetivo Analisar a rugosidade superficial e a estabilidade da cor da resina composta após tratamento de superfície com os discos de óxido de alumínio e posterior exposição à fita clareadora Advanced Teeth Whitening Strips. Métodos Foram confeccionados 20 corpos de prova do restaurador universal Filtek Z350XT (3M®), estes, foram submetidos ao clareamento caseiro por 30 minutos diários durante 14 dias. Utilizou-se um rugosímetro de precisão para verificação da rugosidade através de 3 leituras aleatórias no mesmo sentido em cada amostra, e para estabilidade de cor foi utilizado o sistema CIELAB (valores L*, a*, b*), através do espectofotômetro (MINOLTA CR-321, Japão). As leituras coletadas possibilitaram o cálculo das médias dos corpos de prova e a média de cada grupo. Em seguida, os dados foram submetidos a tratamento estatístico pela análise de variância ANOVA. O nível de significância estabelecido foi de 5% (p≤0,05). Resultados a rugosidade não sofreu grandes variações numéricas e também não houve diferença estatisticamente significantes entre as médias obtidas em relação a rugosidade superficial da resina composta (p=0,44). Contudo, verificou-se que houve diferenças estatisticamente significantes entre as medias obtidas em relação à estabilidade de cor da resina composta, com p= 0,007. Conclusão As fitas pré-contornadas contendo peróxido de hidrogênio a 6% não provocam efeito adverso significantes sobre a rugosidade da resina Z350XT (3M®). Contudo, também concluímos que, de acordo com a análise de estabilidade de cor realizada, poderá haver indicação da substituição das restaurações após o tratamento clareador devido à alteração na coloração das mesmas.

FluoroTome 1: An Apparatus for Tomographic Imaging of Radio-Fluorogenic (RFG) Gels.

Radio-fluorogenic (RFG) gels become permanently fluorescent when exposed to high-energy radiation with the intensity of the emission proportional to the local dose of radiation absorbed. An apparatus is described, FluoroTome 1, that is capable of taking a series of tomographic images (thin slices) of the fluorescence of such an irradiated RFG gel on-site and within minutes of radiation exposure. These images can then be compiled to construct a 3D movie of the dose distribution within the gel. The historical development via a laboratory-bench prototype to a readily transportable, user-friendly apparatus is described. Instrumental details and performance tests are presented.

Estimation of the aboveground biomass and carbon stocks in open Brazilian Savannah developed on sandy soils.

BACKGROUND: The Cerrado is the second largest biome in Brazil and the most biodiverse tropical savannah in the world and acts as a great sequester of atmospheric carbon. The lack of studies related to the quantification of its total biomass compromises the understanding of the dynamics of CO2 in this biome. Thus, it is relevant to develop studies aiming at obtaining accurate estimates of the carbon stock in the different phytophysiognomies that make the Cerrado, to include them in appropriate forest management models. Based on the hypothesis that the amount of carbon stored can vary according to the vegetation typology and vegetation compartments, the aerial stock of dry biomass and carbon were estimated in different compartments (arboreal, herbaceous-shrub and litter). The study was developed in open Brazilian savannah and soils on the sandstone and discussed the effect of fire on this phytophysiognomy. For the arboreal compartment were adjusted mathematical models to fit the biomass equations to estimate the individual stock of the trees in this compartment. The results of the stocks were discussed considering the effect of fire on the phytophysiognomy. RESULTS: Based on the precision and extra distribution measures, the Schumacher-Hall (non-logarithmic) equation presented better results to estimate the individual biomass and carbon stocks of the open Brazilian savannah trees. The aboveground biomass was 12.88 Mg ha-1, corresponding to a total carbon stock of 5.91 Mg ha-1, where most of the stocks are in the herbaceous-shrub compartment (44%). The arboreal compartment accounts for the smallest part of the stocks, followed by the litter. CONCLUSIONS: The observed values are in the interval verified for other areas of savannah studied in Brazil. The values verified for the open Brazilian savannah in sandy soils are at the lower limit of this range, due to the nutrient-poor nature of this type of soil. The distribution of stocks in the different compartments above the ground points to the fragility of this environment to the random fire effect, common in the region. That shows the need for conservation measures for vegetation maintenance and soil protection to preserve adequate nutrient cycling in the ecosystem.