Migration and horizontal gene transfer divide microbial genomes into multiple niches.

Horizontal gene transfer is central to microbial evolution, because it enables genetic regions to spread horizontally through diverse communities. However, how gene transfer exerts such a strong effect is not understood. Here we develop an eco-evolutionary model and show how genetic transfer, even when rare, can transform the evolution and ecology of microbes. We recapitulate existing models, which suggest that asexual reproduction will overpower horizontal transfer and greatly limit its effects. We then show that allowing immigration completely changes these predictions. With migration, the rates and impacts of horizontal transfer are greatly increased, and transfer is most frequent for loci under positive natural selection. Our analysis explains how ecologically important loci can sweep through competing strains and species. In this way, microbial genomes can evolve to become ecologically diverse where different genomic regions encode for partially overlapping, but distinct, ecologies. Under these conditions ecological species do not exist, because genes, not species, inhabit niches.

Nuclear Factor I-C acts as a regulator of hepatocyte proliferation at the onset of liver regeneration.

BACKGROUND & AIMS: Knockout studies of the murine Nuclear Factor I-C (NFI-C) transcription factor revealed abnormal skin wound healing and growth of its appendages, suggesting a role in controlling cell proliferation in adult regenerative processes. Liver regeneration following partial hepatectomy (PH) is a well-established regenerative model whereby changes elicited in hepatocytes lead to their rapid and phased proliferation. Although NFI-C is highly expressed in the liver, no hepatic function was yet established for this transcription factor. This study aimed to determine whether NFI-C may play a role in hepatocyte proliferation and liver regeneration. METHODS: Liver regeneration and cell proliferation pathways following two-thirds PH were investigated in NFI-C knockout (ko) and wild-type (wt) mice. RESULTS: We show that the absence of NFI-C impaired hepatocyte proliferation because of plasminogen activator I (PAI-1) overexpression and the subsequent suppression of urokinase plasminogen activator (uPA) activity and hepatocyte growth factor (HGF) signalling, a potent hepatocyte mitogen. This indicated that NFI-C first acts to promote hepatocyte proliferation at the onset of liver regeneration in wt mice. The subsequent transient down regulation of NFI-C, as can be explained by a self-regulatory feedback loop with transforming growth factor beta 1 (TGF-ß1), may limit the number of hepatocytes entering the first wave of cell division and/or prevent late initiations of mitosis. CONCLUSION: NFI-C acts as a regulator of the phased hepatocyte proliferation during liver regeneration.

Information transfer between large and small two-dimensional polyacrylamide gel electrophoresis.

To determine the feasibility of data transfer, an interlaboratory comparison was conducted on colon carcinoma cell line (DLD-1) proteins resolved by two-dimensional polyacrylamide gel electrophoresis either on small (6 x 7 cm) or large (16x18 cm) gels. The gels were silver-stained and scanned by laser densitometry, and the image obtained was analyzed using Melanie software. The number of spots detected was 1337+/-161 vs. 2382+/-176 for small vs. large format gels, respectively. After gel calibration using landmarks determined using pl and Mr markers, large- and small-format gels were matched and 712+/-36 proteins were found on both types of gels. Having performed accurate gel matching it was possible to acquire additional information after accessing a 2-D PAGE reference database (http://www.expasy.ch/ cgibin/map2/def?DLD1_HUMAN). Thus, the difference in gel size is not an obstacle for data transfer. This will facilitate exchanges between laboratories or consultation concerning existing databases.

Análise dosimétrica de acompanhantes de pacientes de medicina nuclear internados em quarto terapêutico

OBJETIVO: Este trabalho avaliou doses recebidas por acompanhantes que compartilharam o mesmo quarto terapêutico com pacientes tratados com câncer de tireóide ingerindo iodo-131 (131I) e comparou os resultados obtidos aos limites determinados pelas normas brasileiras de radioproteção. MATERIAIS E MÉTODOS: Avaliaram-se seis grupos de pessoas. Cada grupo foi formado por um acompanhante e um paciente, que compartilharam o mesmo quarto terapêutico. Realizaram-se, também, 23 outros experimentos, sendo que nestes um simulador foi usado em substituição à segunda pessoa no quarto terapêutico. As atividades de 131I administradas aos pacientes foram de 3.700 MBq ou 5.550 MBq. Dosímetros termoluminescentes na forma de pó, fluoreto de lítio dopado com magnésio, titânio e sódio foram usados para a avaliação das doses. RESULTADOS: Os resultados mostraram que uma pessoa que compartilha o mesmo quarto terapêutico, durante dois dias, com um paciente tratado com 3.700 MBq ou 5.550 MBq de 131I, seguindo as orientações de radioproteção fornecidas pela equipe médica, é exposta a uma dose média de (0,51 ± 0,02) mSv, para um nível de confiança de 99%. CONCLUSÃO: De acordo com as normas brasileiras, do ponto de vista da radioproteção, não há impedimento acompanhar um paciente de medicina nuclear durante esse tratamento.

Levantamento do controle de qualidade de calibradores de dose de radiofármacos em serviços de medicina nuclear na cidade de São Paulo

OBJETIVO: Realizar levantamento sobre quais testes de controle de qualidade são realizados nos calibradores de dose dos serviços de medicina nuclear da cidade de São Paulo, SP. Estudar a exatidão das medições de atividade de sete calibradores de dose no Laboratório de Calibração de Instrumentos do Instituto de Pesquisas Energéticas e Nucleares, usando fontes de radionuclídeos importantes clinicamente. MATERIAIS E MÉTODOS: O levantamento sobre o controle de qualidade foi realizado a partir de questionários enviados aos serviços. Foram utilizados, no estudo de exatidão dos sete calibradores de dose, fontes de Ga-67, Tc-99m e Tl-201 e um instrumento padrão secundário. RESULTADOS: Os resultados do levantamento sobre os testes de controle de qualidade mostraram algumas impropriedades, por exemplo, a falta da realização diária do teste de reprodutibilidade por todos os serviços. Os resultados do teste de exatidão para os sete calibradores de dose estudados mostraram-se dentro do limite de aceitação da norma nacional (±10%). CONCLUSÃO: A situação com relação ao controle de qualidade de calibradores de dose é insatisfatória, de acordo com o pequeno número de serviços que participaram do levantamento. O estudo da exatidão em sete calibradores de dose não indicou falhas de desempenho e estabeleceu uma calibração desses instrumentos para as fontes utilizadas.

Taxation of nuclear waste in Spain

Law 15/2012 established in Spain four new environmental taxes and extended the scope objective excise duties on mineral oils to tax the use of natural gas and coal as sources of electricity. One of the newly created taxes falls on all electric power producers, and has as tax base the turnover. The second one tax hydropower production, and the other two fall on the nuclear industry. So, there are two new taxes in Spain on the production of electricity from nuclear sources. The first one is a tax on nuclear waste production; the second one is a tax on the storage of nuclear waste. However, these are not the only levies in the Spanish tax system affecting nuclear waste. At the State level there are already several charges on nuclear waste. At the regional level, on the other hand, two Autonomous Communities were taxing nuclear waste. The creation of these new State taxes will finish with the regional taxes, but the State will be oblige to compensate these regions for losing revenues. The purpose of this work is to carry out a critical analysis of the Spanish system of taxation on nuclear waste.

Electron scattering in isotonic chains as a probe of the proton shell structure of unstable nuclei

Electron scattering on unstable nuclei is planned in future facilities of the GSI and RIKEN upgrades. Motivated by this fact, we study theoretical predictions for elastic electron scattering in the N=82, N=50, and N=14 isotonic chains from very proton-deficient to very proton-rich isotones. We compute the scattering observables by performing Dirac partial-wave calculations. The charge density of the nucleus is obtained with a covariant nuclear mean-field model that accounts for the low-energy electromagnetic structure of the nucleon. For the discussion of the dependence of scattering observables at low-momentum transfer on the gross properties of the charge density, we fit Helm model distributions to the self-consistent mean-field densities. We find that the changes shown by the electric charge form factor along each isotonic chain are strongly correlated with the underlying proton shell structure of the isotones. We conclude that elastic electron scattering experiments on isotones can provide valuable information about the filling order and occupation of the single-particle levels of protons.

Effects of medium on nuclear properties in multifragmentation

In multifragmentation of hot nuclear matter, properties of fragments embedded in a soup of nucleonic gas and other fragments should be modified as compared with isolated nuclei. Such modifications are studied within a simple model where only nucleons and one kind of heavy nuclei are considered. The interaction between different species is described with a momentum-dependent two-body potential whose parameters are fitted to reproduce properties of cold isolated nuclei. The internal energy of heavy fragments is parametrized according to a liquid-drop model with density- and temperature-dependent parameters. Calculations are carried out for several subnuclear densities and moderate temperatures, for isospin-symmetric and asymmetric systems. We find that the fragments get stretched due to interactions with the medium and their binding energies decrease with increasing temperature and density of nuclear matter.

Teste de proficiência para medições de radioatividade na medicina nuclear

OBJETIVO: Avaliar o desempenho dos calibradores de radionuclídeos de 55 serviços de medicina nuclear brasileiros em medição de atividade de radiofármaco contendo 99Tc m. Testes de proficiência foram aplicados em 63 resultados originados do programa de comparação promovido pelo Laboratório Nacional de Metrologia das Radiações Ionizantes do Instituto de Radioproteção e Dosimetria. MATERIAIS E MÉTODOS: O desempenho foi avaliado em relação ao critério de aceitação de ±10% de exatidão exigido pela norma brasileira e também aos critérios estabelecidos pela ISO/IEC Guide 43-1, e classificado como "aceitável" ou "não aceitável". Amostras de 99Tc m usadas nas comparações foram fornecidas por alguns dos participantes e calibradas no Laboratório Nacional de Metrologia das Radiações Ionizantes para determinar o valor de referência da atividade. RESULTADOS: Esta comparação com o 99Tc m mostrou que o desempenho aceitável atendendo à exigência da norma regulatória foi de 82,5%, enquanto pelos critérios estabelecidos pela norma ISO/IEC 43-1 foi de 81,0%. Por outro lado, calibradores de radionuclídeos com detector Geiger-Müller apresentaram desempenho inferior quando comparados com os dotados com câmara de ionização. CONCLU-SÃO: Nesta comparação, a avaliação do desempenho baseada nos critérios da ISO/IEC 43-1, os quais são aplicados a laboratórios analíticos, apesar de serem mais restritivas, foi bastante consistente com o critério de exatidão exigido pela norma nacional.

Verifique sus conocimientos sobre medicina nuclear (1): gammagrafía

La presente entrega de la serie de Nursing sobre pruebas complementarias está dedicada a la gammagrafía. La gammagrafía es una técnica de diagnóstico por la imagen de medicina nuclear. Las exploraciones de medicina nuclear se pueden clasificar en medicina nuclear convencional (gammagrafía) y medicina nuclear por tomografía por emisión de positrones (PET), que se estudiará en la siguiente entrega de Nursing sobre pruebas complementarias. La gammagrafía es una técnica diagnóstica que utiliza sustancias radiactivas (isótopos) para estudiar la anatomía y el funcionalismo de diferentes órganos y tejidos del cuerpo. La gran ventaja de esta modalidad diagnóstica es su carácter funcional y su capacidad para evidenciar procesos pre-anatómicos de desarrollo patológico o anómalo que, junto con su elevada sensibilidad, permite diagnosticar alteraciones en fases muy precoces para poder ser tratadas. En el presente artículo se exponen las pruebas diagnósticas de gammagrafía más habituales, teniendo en cuenta que también existe la posibilidad de tratamientos terapéuticos que no son objeto de este trabajo. La enfermera, además del cuidado del paciente durante la preparación y después de la técnica, puede resolver las inquietudes relacionadas con las exploraciones gammagráficas, que normalmente tienen que ver con las características de cada prueba, la duración y el grado de molestia.

Verifique sus conocimientos sobre medicina nuclear (2): tomografía por emisión de positrones (PET) y PET con tomografía computerizada (PET-TC)

La presente entrega de la serie de Nursing sobre las pruebas complementarias está dedicada a la tomografía por emisión de positrones o PET, acrónimo de positron emission tomography. La PET es una técnica de diagnóstico por la imagen de medicina nuclear en la cual se administra al paciente un radiofármaco emisor de positrones. Este radiofármaco se incorpora a los tejidos adecuados siguiendo una vía metabólica determinada. La radiactividad emitida por esos tejidos del paciente es detectable por los equipos PET y se obtienen imágenes que proporcionan una información funcional in vivo. El radiofármaco PET más habitual es un análogo de la glucosa que se llama F-18-fluordesoxiglucosa, conocido como FDG, el cual permite estudiar la actividad metabólica. La incorporación de la tomografía computarizada (TC) en el mismo equipo híbrido PET-TC permite obtener además la información anatómica del paciente. En el presente artículo se describen los fundamentos físicos y fisiológicos básicos de las exploraciones PET-TC con FDG en oncología, así como los procedimientos de enfermería necesarios para el cuidado del paciente y la correcta obtención de las imágenes.

Transition of young people with chronic conditions: a cross-sectional study of patient perceptions before and after transfer from pediatric to adult health care.

UNLABELLED: The aim of this study was to compare perceived barriers to and the most preferred age for successful transition to adult health care between young people with chronic disorders who had not yet transferred from pediatric to adult health care (pre-transfer) and those who had already transferred (post-transfer). In a cross-sectional study, we compared 283 pre-transfer with 89 post-transfer young people, using a 28-item questionnaire that focused on perceived barriers to transition and beliefs about the most preferred age to transfer. Feeling at ease with the pediatrician was the most important barrier to successful transition in both groups, but was rated significantly higher in the pre-transfer compared to the post-transfer group (OR = 2.03, 95 %CI 1.12-3.71). Anxiety and lack of information were the next most important barriers, rated equally highly by the two groups (OR = 0.67, 95 %CI 0.35-1.28 and OR = 0.71, 95 %CI 0.36-1.38, respectively). More than 80 % of the respondents in both groups reported that 16-19 years was the most preferred age to transfer; more than half of all the respondents reported 18-19 years and older as the most preferred age. CONCLUSION: Better transition planning through the provision of regular and more detailed information about adult health-care providers and the transition process could reduce anxiety and contribute to a more positive attitude to overcome perceived barriers to transition from young people's perspective. Young people's preferences about transferring to adult health care provide a challenge to those children's hospitals that transfer to adult health care at a younger age.