Genetic transformation of novel isolates of chicken Lactobacillus bearing probiotic features for expression of heterologous proteins: a tool to develop live oral vaccines

BACKGROUND: The use of lactic acid bacteria as vehicles to delivery antigens to immunize animals is a promising issue. When genetically modified, these bacteria can induce a specific local and systemic immune response against selected pathogens. Gastric acid and bile salts tolerance, production of antagonistic substances against pathogenic microorganisms, and adhesive ability to gut epithelium are other important characteristics that make these bacteria useful for oral immunization. RESULTS: Bacteria isolated on de Man, Rogosa and Sharpe medium (MRS) from different gastrointestinal portions of broiler chicks were evaluated for their resistance to artificial gastric acid and bile salts, production of hydrogen peroxide, and cell surface hydrophobicity. Thirty-eight isolates were first typed at species level by PCR amplification of 16S-23S rRNA intergenic spacers using universal primers that anneal within 16S and 23S genes, followed by restriction digestion analyses of PCR amplicons (PCR-ARDRA). An expression cassette was assembled onto the pCR2.1-Topo vector by cloning the promoter, leader peptide, cell wall anchor and terminator sequences derived from the laminin binding S-layer protein gene of L. crispatus strain F5.7 (lbs gene). A sequence encoding the green fluorescent protein (GFP) was inserted as reporter gene, and an erythromycin resistance gene was added as selective marker. All constructs were able to express GFP in the cloning host E. coli XL1-Blue and different Lactobacillus strains as verified by FACS and laser scanning confocal microscopy. CONCLUSION: Lactobacillus isolated from gastrointestinal tract of broiler chickens and selected for probiotic characteristics can be genetically modified by introducing an expression cassette into the lbs locus. The transformed bacteria expressed on its cell wall surface different fluorescent proteins used as reporters of promoter function. It is possible then that similar bacterial model expressing pathogen antigens can be used as live oral vaccines to immunize broilers against infectious diseases

Redução de fratura de maxila em equino por odontossíntese e osteossíntese semi-rígida

O artigo não apresenta resumo

Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

BACKGROUND: To report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy. METHODS: Between August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months. RESULTS: From the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042). CONCLUSION: IMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication

Unrevealing the interactive effects of climate change and oil contamination on lab-simulated estuarine benthic communities

There is growing concern that modifications to the global environment such as ocean acidification and increased ultraviolet radiation may interact with anthropogenic pollutants to adversely affect the future marine environment. Despite this, little is known about the nature of the potential risks posed by such interactions. Here, we performed a multifactorial microcosm experiment to assess the impact of ocean acidification, ultraviolet radiation B (UV-B) and oil hydrocarbon contamination on sediment chemistry, the microbial community (composition and function) and biochemical marker response of selected indicator species. We found that increased ocean acidification and oil contamination in the absence of UV-B will significantly alter bacterial composition by, among other changes, greatly reducing the relative abundance of Desulfobacterales, known to be important oil hydrocarbon degraders. Along with changes in bacterial composition, we identified concomitant shifts in the composition of aromatic hydrocarbons in the sediment and an increase in oxidative stress effects on our indicator species. Interestingly, our study identifies UV-B as a critical component in the interaction between these factors, since its presence alleviates harmful effects caused by the combination of reduced pH and oil pollution. The model system used here shows that the interactive effect of reduced pH and oil contamination can adversely affect the structure and functioning of sediment benthic communities, with the potential to exacerbate the toxicity of oil hydrocarbons in marine ecosystems

Stabilizability and Disturbance Rejection with State-Derivative Feedback

In some practical problems, for instance in the control of mechanical systems using accelerometers as sensors, it is easier to obtain the state-derivative signals than the state signals. This paper shows that (i) linear time-invariant plants given by the state-space model matrices {A,B,C,D} with output equal to the state-derivative vector are not observable and can not be stabilizable by using an output feedback if det⁡(A)=0 and (ii) the rejection of a constant disturbance added to the input of the aforementioned plants, considering det⁡(A)≠0, and a static output feedback controller is not possible. The proposed results can be useful in the analysis and design of control systems with state-derivative feedback

Aspectos moleculares da transmissão sináptica

O Sistema Nervoso Central produz o nosso estado consciente mediante um contínuo fluxo de informações e armazenamento de memórias ao longo da vida, a partir de diferentes estímulos externos. Ao mesmo tempo, controla a concentração dos nossos fluidos internos e o trabalho de músculos e glândulas. A transmissão sináptica é o processo básico de toda esta atividade. Bilhões de neurônios se comunicam entre si via milhares de sinapses, e cada sinapse, por sua vez, é uma estrutura regulada independentemente. A partir desta complexidade, em lugar de caos, surge uma singular ordem na informação processada pelo cérebro. A secreção de neurotransmissores na zona ativa da sinapse é o evento primário da comunicação interneuronal. Este processo é regulado por um tráfego de membranas altamente orquestrado dentro do terminal présináptico. Os neurotransmissores são armazenados em vesículas sinápticas. A despolarização de um terminal nervoso por um potencial de ação resulta na abertura de canais de cálcio, operados por voltagem. O influxo de Ca resultante deflagra a exocitose, que é uma rápida fusão de vesículas com a membrana plasmática, liberando neurotransmissores para a fenda sináptica. A exocitose envolve a junção de proteínas intrínsecas das membranas plasmáticas, vesicular e pré-sináptica, mediante proteínas específicas de ancoragem e fusão na zona ativa (SNARE). Em seguida à liberação, as membranas das vesículas são rapidamente reincorporadas via endocitose e recicladas dentro do terminal sináptico. O terminal é, portanto, uma unidade autônoma que contém todos os elementos requeridos para a exocitose das vesículas, as proteínas responsáveis pela biossíntese do neurotransmissor e recaptação das vesículas. Uma vez liberado, o neurotransmissor difunde através da fenda sináptica e interage com proteínas receptoras na membrana do neurônio póssináptico produzindo, em uma fração de milissegundo, uma permeabilidade intensa e temporária aos íons Na + e K+, provocando a despolarização total de cerca de 100 mV desde um potencial de repouso em torno de -60mV. Isto gera um potencial de ação que se difunde ao longo da membrana do neurônio pós-sináptico, podendo alcançar o seu próprio  erminal e deflagrar novo movimento de Ca 2+ para o citosol, gerando um novo potencial. Várias proteínas dentro do terminal pós-sináptico estão envolvidas neste processo. É geralmente aceito que os processos de aprendizado e memória resultam de mudanças estruturais e bioquímicas em sinapses específicas que alteram a liberação de neurotransmissores e a ação pós-sináptica. Tais alterações podem ser registradas eletrofisiologicamente como uma potenciação ou depressão de duração longa (LTP ou LTD) ou a combinação de ambas. The Central Nervous System produces our conscious state out of various externa inputs in a continuous stream of information and storing a lifetime of memories, while keeping track of the concentration of our internal fluids and the work of muscles and glands. Synaptic transmission is the key process of all that activity. Billions of neurons communicate with each other via thousands of synapses, each of which is independently regulated. From that complexity, instead of chaos, arises the pristine order of information processed by the brain. The secretion of neurotransmitters at the synaptic active zone is the primary event of interneuronal communication. This process is regulated by a highly orchestrated cycle of membrane trafficking within the presynaptic nerve terminal. Neurotransmitters are stored in synaptic vesicles. Depolarization of the nerve terminal by an action potential results in the opening of voltage-gated Ca 2+ channels. The resulting influx of calcium ions triggers exocytosis which is a rapid fusion of the vesicles with the plasma membrane, releasing neurotransmitters into the synaptic cleft. Exocytosis involves the linking of intrinsic membrane proteins of the vesicle and the plasma membranes by specific docking and fusion, the SNARE proteins, at the active zone. The vesicle membranes are rapidly retrieved by endocytosis and the synaptic vesicles recycled within the nerve terminal. The nerve terminal is thus an autonomous unit that contains all elements required for synaptic vesicle exocytosis and proteins responsible for neurotransmitter biosynthesis and vesicular uptake. Once the neurotransmitter have been released, diffuses across the synaptic cleft and combines with receptor molecules in the membrane of the postsynaptic neuron producing, in a fraction millisecond, a large transient increased permeability to Na + and K+ ions, provoking a net depolarization to about 100mV from the resting potential of about -60mV. This generates an action potential which spreads along the surface of the postsynaptic cell membrane which in turn may trigger Ca 2+ movement to the cytosol in the synaptic terminal to generate a new response. Several proteins inside the post synaptic terminal are involved in this process. It is generally accepted that learning and memory result from structural and biochemical changes in specific synapses which alter neurotransmitter release and post synaptic action. These alterations are perceivable electrophysiologically as a long term potentiation (LTP),long term depression (LTD), or a combination of both.&nbsp

Metodología activa en el proceso de aprendizaje: estudio realizado con estudiantes del segundo Ciclo, 4º. 5º. Y 6º grado del nivel primario de la Escuela Oficial Rural Mixta del Cantón Llano del Pinal, Quetzaltenango.

Estudio realizado con estudiantes del segundo ciclo del nivel de Educación Primaria, que comprende el cuarto, quinto y sexto grado de la Escuela Oficial Rural Mixta del Cantón Llano del Pinal, Quetzaltenango. El objetivo fue establecer la incidencia de la metodología activa en el proceso de aprendizaje. El enfoque que se utilizó fue cualitativo; mientras que las técnicas fueron la investigación documental e investigación de campo. Se aplicó el método aleatorio, la muestra fue de 102 estudiantes y 31 docentes. Se propone al personal docente un Manual de técnicas y estrategias de metodología activa, para que tengan una guía de aplicación que le permita apropiarse de esa herramienta en forma consciente, de tal forma que su desarrollo no sea producto de la imposición, sino que esté intrínsecamente ligado a la necesidad de participar en la consecución de un verdadero proceso de aprendizaje de los estudiantes