981 resultados para Estádio serial
Resumo:
With the aid of the cobalt labelling technique, frog spinal cord motor neuron dendrites of the subpial dendritic plexus have been identified in serial electron micrographs. Computer reconstructions of various lengths (2.5-9.8 micron) of dendritic segments showed the contours of these dendrites to be highly irregular, and to present many thorn-like projections 0.4-1.8 micron long. Number, size and distribution of synaptic contacts were also determined. Almost half of the synapses occurred at the origins of the thorns and these synapses had the largest contact areas. Only 8 out of 54 synapses analysed were found on thorns and these were the smallest. For the total length of reconstructed dendrites there was, on average, one synapse per 1.2 micron, while 4.4% of the total dendritic surface was covered with synaptic contacts. The functional significance of these distal dendrites and their capacity to influence the soma membrane potential is discussed.
Resumo:
Neuroblastoma (NB) is a neural crest-derived childhood tumor characterized by a remarkable phenotypic diversity, ranging from spontaneous regression to fatal metastatic disease. Although the cancer stem cell (CSC) model provides a trail to characterize the cells responsible for tumor onset, the NB tumor-initiating cell (TIC) has not been identified. In this study, the relevance of the CSC model in NB was investigated by taking advantage of typical functional stem cell characteristics. A predictive association was established between self-renewal, as assessed by serial sphere formation, and clinical aggressiveness in primary tumors. Moreover, cell subsets gradually selected during serial sphere culture harbored increased in vivo tumorigenicity, only highlighted in an orthotopic microenvironment. A microarray time course analysis of serial spheres passages from metastatic cells allowed us to specifically "profile" the NB stem cell-like phenotype and to identify CD133, ABC transporter, and WNT and NOTCH genes as spheres markers. On the basis of combined sphere markers expression, at least two distinct tumorigenic cell subpopulations were identified, also shown to preexist in primary NB. However, sphere markers-mediated cell sorting of parental tumor failed to recapitulate the TIC phenotype in the orthotopic model, highlighting the complexity of the CSC model. Our data support the NB stem-like cells as a dynamic and heterogeneous cell population strongly dependent on microenvironmental signals and add novel candidate genes as potential therapeutic targets in the control of high-risk NB.
Resumo:
Background: Blood pressure (BP) is strongly associated with body weight and there is concern that the pediatric overweight epidemic could lead to an increase in children's mean BP. Objectives: We analyzed BP trends from 1998 to 2006 among children of the Seychelles, a rapidly developing middle-income country in Africa. Methods: Serial school-based surveys of weight, height and BP were conducted yearly between 1998-2006 among all students of the country in four school grades (kindergarten, 4th, 7th and 10th years of compulsory school). We used the CDC criteria to define "overweight" (BMI _95th sex-, and age-specific percentile) and the NHBPEP criteria for "elevated BP" (BP _95th sex-, age-, and height specific percentile). Methods for height, weight, and BP measurements were identical over the study period. The trends in mean BMI and mean systolic/diastolic BP were assessed with linear regression. Results: 27,703 children aged 4-18 years (participation rate: 79%) contributed 43,927 observations on weight, height, and BP. The prevalence of overweight increased from 5.1% in 1998-2000 to 8.1% in 2004-2006 among boys, and from 6.1% to 9.1% among girls, respectively. The prevalence of elevated BP was 8.4% in 1998-2000 and 6.9% in 2004-2006 among boys; 9.8% and 7.8% among girls, respectively. Over the 9-years study period, age-adjusted body mass index (BMI) increased by 0.078 kg/m2/year in boys and by 0.083 kg/m2/year in girls (both sexes, P_0.001). Age- and height-adjusted systolic BP decreased by -0.37 mmHg/year in boys and by -0.34 mmHg/year in girls (both sexes, P_0.001). Diastolic BP did not change in boys (-0.02 mmHg/year, P: 0.40) and slightly increased in girls (0.07 mmHg/year, P: 0.003). These trend estimates were altered modestly upon further adjustment for BMI or if analyses were based on median rather than mean values. Conclusion: Although body weight increased markedly between 1998 and 2006 in this population, systolic BP decreased and diastolic BP changed only marginally. This suggests that population increases in body weight are not necessarily associated with corresponding rises in BP in children.
Resumo:
Foram feitas observações do ciclo evolutivo do Triatoma vitticeps com alimentação semanal em camundongo, em condições de laboratório. De quatro casais virgens obtiveram-se 435 ovos, sendo que 149 destinaram-se ao ciclo evolutivo e 286 ao estudo da resistência ao jejum, o que constituirá a segunda etapa deste trabalho. Apenas 50 exemplares atingiram a fase adulta num período X (S) = 270 ± 45 dias. Quanto ao tempo de incubação, o 1° e o 2° estádios foram realizados, cada um, em menos de um mês, enquanto que os 3º, 4º e 5º estádios requereram cerca de um, dois e três meses, respectivamente. A procura pelo 1º repasto ocorreu de forma sensível no 3º, 6º e 10º dias. Em todos os estádios, mais de 50% dos exemplares realizaram apenas um repasto, com exceção do 5º, onde foram necessários dois. No que diz respeito ao intervalo de tempo entre o oferecimento do repasto, o ato de picar, e a duração do repasto, observou-se que estes aumentaram gradativamente de acordo com o estádio. Dos 423 repastos realizados, 390 não foram seguidos de defecação no prazo de 10 min. Sob este aspecto parece que o T. vitticeps não é um bom transmissor do T. cruzi. O experimento teve a duração de 13 meses e neste período as temperaturas máximas e mínimas e a umidade relativa do ar variaram em média de 28 ± 2°C a 25 ± 2°C e 80 ± 2%, respectivamente. O material é proveniente da criação mantida no Departamento de entomologia do Instituto Oswaldo Cruz.
Resumo:
Road safety has become an increasing concern in developed countries due to the significant amount of mortal victims and the economic losses derived. Only in 2005 these losses rose to 200.000 million euros, a significant amount - approximately the 2% of its GDP- that easily justifies any public intervention. One tool used by governments to face this challenge is the enactment of stricter policies and regulations. Since drunk driving is one of the most important concerns of public authorities on this field, several European countries decided to lower their illegal Blood Alcohol Content levels to 0.5 mg/ml during the last decade. This study evaluates for the first time the effectiveness of this transition using European panel-based data (CARE) for the period 1991-2003 using the Differences-in-Differences method in a fixed effects estimation that allows for any pattern of correlation (Cluster-Robust). My results show the existence of positive impacts on certain groups of road users and for the whole population when the policy is accompanied by some enforcement interventions. Moreover, a time lag of more than two years is found in that effectiveness. Finally, I also assert the importance of controlling for serial correlation in the evaluation of this kind of policies.
Resumo:
Em prosseguimento ao estudo da biologia do Triatoma vitticeps (Gonçalves et al., 1988), foram feitas observações sobre a sua resistência ao jejum. Dos 286 ovos obtidos, apenas 201 eclodiram e atingiram o estádio pretendido para as observações. Os demais não eclodiram, não completaram a muda ou morreram sem motivo aparente. As ninfas foram acondicionadas, individualmente em frascos de Borrel, devidamente registrados. Para a alimentação foram utilizados camundongos e a medida que as ninfas atingiam o estágio pretendido a alimentação era suspensa até ocorrer a morte. A avaliação da resistência ao jejum foi feita da seguinte forma: o intervalo de dias entre o último repasto e a morte e entre a muda e a morte. Verificou-se que a resistência está diretamente relacionada com a fase de desenvolvimento. Para os parâmetros último repasto/morte e muda/morte, ambos os sexos foram menos resistentes do que as ninfas de 3º e 2º estádios, respectivamente. O experimento teve duração de 15 meses e neste período as temperaturas máxima e mínima e a umidade relativa do ar variaram em média de 25 ± 2ºC e 81 ± 3% UR, respectivamente. O material foi proveniente da criação de triatomíneos mantida no Departamento de Entomologia do Instituto Oswaldo Cruz.
Resumo:
El sistema desarrollado en este trabajo permite la detección de fatiga del músculo de un paciente. Las señales electromiográficas generadas por el músculo son detectadas mediante electrodos superficiales, que sirven de entrada al circuito hacia los diferentes canales de entrada. Tras una primera etapa de amplificación, las señales son filtradas por un filtro pasabanda. Las señales acondicionadas se digitalizan mediante un conversor analógico digital que está conectado a un microcontrolador. Éste establece la comunicación con el PC enviándole los datos a través del puerto serie. Finalmente, mediante un programa implementado en Labview se procesan los datos y se determina la existencia o no de fatiga muscular.
Resumo:
Foi feito um estudo sobre a resistência ao jejum em todas as fases evolutivas e pesagens em diferentes situações nutricionais de Triatoma lecticularia (alimentado; não alimentado; na morte após o jejum) com temperatura e umidade registradas. Observou-se que os períodos de resistência das fases ninfais apresentaram médias (dias) crescentes: 1º: 45,84; 2º: 61; 3º: 88,74; 4º: 123,47; 5º 162,30. Na fase adulta as médias foram aproximadas à do 3º estádio (para os machos 88,94 e para as fêmeas 83,66). O procedimento de pesagens permitiu registrar a quantidade de sangue ingerido, a perda de peso durante o jejum e o respectivo percentual em relação ao peso inicial. Esta espécie tem assinalada sua distribuição geográfica na região Neártica, onde tem sido encontrda infectada com Trypanosoma cruzi associada a Neotoma micropus Baird e Spermophilus variagatus (Erxeleben).
Resumo:
The migration of larval Schistosoma mansoni was tracked by means of autoradiographic analysis in naive rabbits percutaneously exposed to L-(**75 Se) selenomethionine-labeled cercariae on serial intervals of 1, 2, 4, 6, 8, 10, 15, 20, 25, 30, 40 and 50 days post-infection. Autoradiographic foci were detected from the 1st day in the skin, up to the 15th day in the liver. Adult and mature worms were recovered either paired or not 60 days after infection, by perfusion of hepatic and mesenteric veins. Morphometric analysis under optical microscopy, showed that worms were within regular dimention limits as compared to adult worms harboured by other host species. These observations extend previous informations on the S. mansoni-rabbit association and clearly demonstrate the post-liver phase of S.mansoni life-cycle in this host.
Resumo:
Este trabajo analiza el rendimiento de cuatro nodos de cómputo multiprocesador de memoria compartida para resolver el problema N-body. Se paraleliza el algoritmo serie, y se codifica usando el lenguaje C extendido con OpenMP. El resultado son dos variantes que obedecen a dos criterios de optimización diferentes: minimizar los requisitos de memoria y minimizar el volumen de cómputo. Posteriormente, se realiza un proceso de análisis de las prestaciones del programa sobre los nodos de cómputo. Se modela el rendimiento de las variantes secuenciales y paralelas de la aplicación, y de los nodos de cómputo; se instrumentan y ejecutan los programas para obtener resultados en forma de varias métricas; finalmente se muestran e interpretan los resultados, proporcionando claves que explican ineficiencias y cuellos de botella en el rendimiento y posibles líneas de mejora. La experiencia de este estudio concreto ha permitido esbozar una incipiente metodología de análisis de rendimiento, identificación de problemas y sintonización de algoritmos a nodos de cómputo multiprocesador de memoria compartida.
Resumo:
BACKGROUND: We analysed 5-year treatment with agalsidase alfa enzyme replacement therapy in patients with Fabry's disease who were enrolled in the Fabry Outcome Survey observational database (FOS). METHODS: Baseline and 5-year data were available for up to 181 adults (126 men) in FOS. Serial data for cardiac mass and function, renal function, pain, and quality of life were assessed. Safety and sensitivity analyses were done in patients with baseline and at least one relevant follow-up measurement during the 5 years (n=555 and n=475, respectively). FINDINGS: In patients with baseline cardiac hypertrophy, treatment resulted in a sustained reduction in left ventricular mass (LVM) index after 5 years (from 71.4 [SD 22.5] g/m(2.7) to 64.1 [18.7] g/m(2.7), p=0.0111) and a significant increase in midwall fractional shortening (MFS) from 14.3% (2.3) to 16.0% (3.8) after 3 years (p=0.02). In patients without baseline hypertrophy, LVM index and MFS remained stable. Mean yearly fall in estimated glomerular filtration rate versus baseline after 5 years of enzyme replacement therapy was -3.17 mL/min per 1.73 m(2) for men and -0.89 mL/min per 1.73 m(2) for women. Average pain, measured by Brief Pain Inventory score, improved significantly, from 3.7 (2.3) at baseline to 2.5 (2.4) after 5 years (p=0.0023). Quality of life, measured by deviation scores from normal EuroQol values, improved significantly, from -0.24 (0.3) at baseline to -0.17 (0.3) after 5 years (p=0.0483). Findings were confirmed by sensitivity analysis. No unexpected safety concerns were identified. INTERPRETATION: By comparison with historical natural history data for patients with Fabry's disease who were not treated with enzyme replacement therapy, long-term treatment with agalsidase alfa leads to substantial and sustained clinical benefits. FUNDING: Shire Human Genetic Therapies AB.
Resumo:
To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.
Resumo:
In correlative microscopy, light microscopy provides the overview and orientation of the complex cells and tissue, while electron microscopy offers the detailed localization and correlation of subcellular structures. In this chapter we offer detailed high-quality electron microscopical preparation methods for optimum preservation of the cellular ultrastructure. From such preparations serial thin sections are collected and used for comparative histochemical, immunofluorescence, and immunogold staining.In light microscopy histological stains identify the orientation of the sample and immunofluorescence labeling facilitates to find the region of interest, namely, the labeled cells expressing the macromolecule under investigation. Sections, labeled with immunogold are analyzed by electron microscopy in order to identify the label within the cellular architecture at high resolution.
Resumo:
In this work we have studied the modifications in the biological properties of Trypanosoma cruzi when the parasite is maintained for a long time in axenic culture. The studies were done with a clone from an avirulent strain (Dm30L) and a non-cloned virulent strain (EP) of T. cruzi. Both parasiteswere maintained, for at least three years, by successive triatomine/mouse alternate passage (control condition), or by serial passage in axenic medium (culture condition), or only in the mouse (mouse condition). The comparison between parasites of culture and control condition showed that metacyclogenesis capacity was reduced in the former and that the resulting metacyclics displayed an attenuatedvirulence. In order to compare the virulence of metacyclics from the urine of the insect vector, Rhodnius prolixus were infected by artificial feeding with parasites of the control or culture condition. After three triatomine/triatomine passages, there was observed an almost identical biological behavior for these parasites, hence indicating that the maintenance of T. cruzi for a long time in axenic culture affects the differentiation capacity and the virulence of the parasite. Additionally, it was demonstrated that it is possible to maintain T. cruzi exclusively through passages in the invertebrate host.
Resumo:
Summary : Cancer stem cells (CSC) that display tumor-initiating properties have recently been identified in several distinct types of malignancies, holding promise for more effective therapeutic strategies. However, evidence of such cells in sarcomas, which include some of the most aggressive and therapy-resistant tumors, has not been demonstrated to date. Here, we .identify and characterize cancer stem cells in Ewing's sarcoma family tumors (ESPY), a highly aggressive pediatric malignancy believed to be of mesenchymal stem cell (MSC) origin. Using magnetic bead cell separation of primary ESFT, we have isolated a subpopulation of CD133+ tumor cells that display the capacity to initiate and sustain tumor growth through serial transplantation in NOD/SCID mice, re-establishing at each in vivo passage the parental tumor phenotype and hierarchical cell organization. Consistent with the plasticity of MSCs, in vitro differentiation assays showed that the CD133+ cell population retained the ability to differentiate along adipogenic, osteogenic and chondrogenic lineages. Quantitative Real-Time PCR analysis of genes implicated in stem cell maintenance revealed that CD133+ ESFT cells express significantly higher levels of OCT4 and NANOG than their CD133- counterparts. Taken together, our observations provide the first identification of ESFT cancer stem cells (ET-CSC) and demonstration of their mesenchymal stem cell properties, a critical step toward a better biological understanding and rational therapeutic targeting of these tumors. Résumé : Des cellules souches tumorales avec des propriétés exclusives d'initiation tumorale ont récemment été identifiées dans différents types de cancers, permettant ainsi d'espérer le développement de thérapies plus efficaces. Cependant, l'existence de telles cellules dans les sarcomes, un sous-groupe de cancers d'origine mésenchymateuse très agressifs, n'a pas encore été démontrée. Dans ce travail de recherche, nous identifions et caractérisons des cellules souches tumorales dans le sarcome d'Ewing, une tumeur pédiatrique très agressive vraisemblablement dérivée de cellules souches mésenchymateuses (MSC). Afin de séparer des populations cellulaires dans des échantillons primaires de sarcome d'Ewing, nous avons utilisé des billes magnétiques couplées à des anticorps monoclonaux. Ceci nous a permis d'isoler une sous-population de cellules tumorales CD133+ qui ont la capacité d'initier et de maintenir la croissance tumorale dans des xénotransplantations en série effectuées dans des souris immunodéficientes NOD/SCID. Ces cellules reétablissent à chaque passage in vivo le phénotype de la tumeur d'origine ainsi que son organisation hiérarchique. En accord avec la plasticité des MSC, des tests de différentiation in vitro ont montré que les cellules CD133+ maintiennent la capacité de se différentier en adipocytes, ostéocytes et chondrocytes. Une analyse par PCR quantitative de gènes impliqués dans le maintien des cellules souches a montré que les cellules CD133+ expriment un niveau beaucoup plus élevé de OCT4 and NANOG que les cellules CD133-. En résumé, nos observations constituent la première identification de cellules souches tumorales dans le sarcome d'Ewing et démontrent leur propriété de cellules souches mésenchymateuses. Ceci constitue une étape clé vers une meilleure compréhension biologique et une meilleure approche thérapeutique de ces tumeurs.