25 research outputs found
3-Dimensional Electron Microscopy of Biological Specimens
No full textThree-dimensional (3D) imaging is an important tool in electron microscopy, especially in biological specimens where the main focus is the structure of the cells. Many times important information is lost because the exact orientation of a specimen is unknown. We tested two different 3D imaging techniques, focused ion beam (FIB) slice and view, and cryo-FIB thinning of samples for use in cryo transmission electron tomography (cryo-TEM) and cryo-electron tomography (cryo-ET).
We began our research with room temperature FIB slice and view, with an intention to move onto slice and view at cryogenic temperatures. We found this technique to be difficult to control and the time required to produce results was simply too high. We moved on to investigating cryo-FIB milling as a tool for thinning cryo-ET specimens. Advances in cryo-ET have enabled high-resolution 3D imaging of complex assemblies and determination of cellular architectures in their close-to-native states. However, one major limitation, the accessible specimen thickness, has hindered its broader application in cellular biology. Recent efforts have been made to create thin, frozen-hydrated sections using cryo-ultramicrotomy, but with many mechanical artifacts and low yields. Here, we report a method that applies a focused ion beam (FIB) at cryogenic temperature (cryo-FIB) to reduce the thickness of frozen-hydrated cells, including mammalian cells, to a degree suitable for cryo-ET
Thermotoga lettingae sp. nov., a novel thermophilic, methanol-degrading bacterium isolated from a thermophilic anaerobic reactor
No full textA novel, anaerobic, non-spore-forming, mobile, Gram-negative, thermophilic bacterium, strain TMO(T), was isolated from a thermophilic sulfate-reducing bioreactor operated at 65 degrees C with methanol as the sole substrate. The G C content of the DNA of strain TMO(T) was 39.2 molÐThe optimum pH, NaCl concentration, and temperature for growth were 7.0, 1.0°and 65 degrees C, respectively. Strain TMO(T) was able to degrade methanol to CO(2) and H(2) in syntrophic culture with Methanothermobacter thermautotrophicus DeltaH or Thermodesulfovibrio yellowstonii. Thiosulfate, elemental sulfur, Fe(III) and anthraquinone-2,6-disulfonate were able to serve as electron acceptors during methanol degradation. In the presence of thiosulfate or elemental sulfur, methanol was converted to CO(2) and partly to alanine. In pure culture, strain TMO(T) was also able to ferment methanol to acetate, CO(2) and H(2). However, this degradation occurred slower than in syntrophic cultures or in the presence of electron acceptors. Yeast extract was required for growth. Besides growing on methanol, strain TMO(T) grew by fermentation on a variety of carbohydrates including monomeric and oligomeric sugars, starch and xylan. Acetate, alanine, CO(2), H(2), and traces of ethanol, lactate and alpha-aminobutyrate were produced during glucose fermentation. Comparison of 16S rDNA genes revealed that strain TMO(T) is related to Thermotoga subterranea (98€and Thermotoga elfii (98Ž The type strain is TMO(T) (=DSM 14385(T)=ATCC BAA-301(T)). On the basis of the fact that these organisms differ physiologically from strain TMO(T), it is proposed that strain TMO(T) be classified as a new species, within the genus Thermotoga, as Thermotoga lettingae
The development and validation of a multidimensional measure of male body dissatisfaction and its preliminary use in exploring the relationship between body dissatisfaction and exercise
No full textHistorically, research has focused predominately on female experience of body dissatisfaction (BD). More recently there has been an increased focus upon BD in men. The current literature review indicates that research in BD in men is its infancy compared to BD in females and the review highlights the differences between the experience of BD in men and women and the difficulties in applying evidence that has been found in female samples to males. In line with this, tools used to assess females may not be appropriate to assess males. It is therefore important to develop an instrument that accurately assesses BD in males to identify those who may be at risk. The literature review also pays attention to the coping strategies that men may engage in with a particular focus on exercise and its potential role as both a protective and risk factor.The purpose of the empirical paper was to explore the structure of a new measure: The Male Body Dissatisfaction Inventory (M-BoDI). A Principal Components Analysis revealed a four-component structure. The study provided evidence of concurrent validity for the M-BoDI and good internal reliability and the scores on the M-BoDI were stable over a 4-week period. A significant relationship was found between negative reasons for exercising and BD as measured by the M-BoDI, and negative reasons for exercising were also linked to core excessive exercise features. Implications of the current findings and ideas for further research are discussed
Neonatal sepsis: need for consensus definition, collaboration and core outcomes
No full textThe original version of this Article contained an error in the spelling of the author Marina Degtyareva, which was incorrectly given as Marina Degtyaeva. This has now been corrected in both the PDF and HTML versions of the Article
Competition and coexistence of sulfate-reducing bacteria, acetogens and methanogens in a lab-scale anaerobic bioreactor as affected by changing substrate to sulfate ratio
No full textThe microbial population structure and function of natural anaerobic communities maintained in lab-scale continuously stirred tank reactors at different lactate to sulfate ratios and in the absence of sulfate were analyzed using an integrated approach of molecular techniques and chemical analysis. The population structure, determined by denaturing gradient gel electrophoresis and by the use of oligonucleotide probes, was linked to the functional changes in the reactors. At the influent lactate to sulfate molar ratio of 0.35 mol mol?1, i.e., electron donor limitation, lactate oxidation was mainly carried out by incompletely oxidizing sulfate-reducing bacteria, which formed 80–85% of the total bacterial population. Desulfomicrobium- and Desulfovibriolike species were the most abundant sulfate-reducing bacteria. Acetogens and methanogenic Archaea were mostly outcompeted, although less than 2% of an acetogenic population could still be observed at this limiting concentration of lactate. In the near absence of sulfate (i.e., at very high lactate/sulfate ratio), acetogens and methanogenic Archaea were the dominant microbial communities. Acetogenic bacteria represented by Dendrosporobacter quercicolus-like species formed more than 70% of the population, while methanogenic bacteria related to uncultured Archaea comprising about 10–15% of the microbial community. At an influent lactate to sulfate molar ratio of 2 mol mol?1, i.e., under sulfate-limiting conditions, a different metabolic route was followed by the mixed anaerobic community. Apparently, lactate was fermented to acetate and propionate, while the majority of sulfidogenesis and methanogenesis were dependent on these fermentation products. This was consistent with the presence of significant levels (40–45% of total bacteria) of D.quercicolus-like heteroacetogens and a corresponding increase of propionate-oxidizing Desulfobulbus-like sulfate-reducing bacteria (20% of the total bacteria). Methanogenic Archaea accounted for 10% of the total microbial community.BiotechnologyApplied Science
Microbiological analysis of the population of extremely haloalkaliphilic sulfur-oxidizing bacteria dominating in lab-scale sulfide-removing bioreactors
No full textThiopaq biotechnology for partial sulfide oxidation to elemental sulfur is an efficient way to remove H2S from biogases. However, its application for high-pressure natural gas desulfurization needs upgrading. Particularly, an increase in alkalinity of the scrubbing liquid is required. Therefore, the feasibility of sulfide oxidation into elemental sulfur under oxygen limitation was tested at extremely haloalkaline conditions in lab-scale bioreactors using mix sediments from hypersaline soda lakes as inoculum. The microbiological analysis, both culture dependent and independent, of the successfully operating bioreactors revealed a domination of obligately chemolithoautotrophic and extremely haloalkaliphilic sulfur-oxidizing bacteria belonging to the genus Thioalkalivibrio. Two subgroups were recognized among the isolates. The subgroup enriched from the reactors operating at pH 10 clustered with Thioalkalivibrio jannaschii–Thioalkalivibrio versutus core group of the genus Thioalkalivibrio. Another subgroup, obtained mostly with sulfide as substrate and at lower pH, belonged to the cluster of facultatively alkaliphilic Thioalkalivibrio halophilus. Overall, the results clearly indicate a large potential of the genus Thiolalkalivibrio to efficiently oxidize sulfide at extremely haloalkaline conditions, which makes it suitable for application in the natural gas desulfurizationBiotechnologyApplied Science
Spin-orbit interaction in chiral carbon nanotubes probed in pulsed magnetic fields
No full textThe magneto-conductance of an open carbon nanotube (CNT)-quantum wire was measured in pulsed magnetic fields. At low temperatures we find a peculiar split magneto-conductance peak close to the charge neutrality point. Our analysis of the data reveals that this splitting is intimately connected to the spin-orbit interaction and the tube chirality. Band structure calculations suggest that the current in the peak regions is highly spin-polarized, which calls for application in future CNT-based spintronic devices
Research on Scientific Journals: Implications for Editors and Authors
No full textA review of editorial policies of leading journals and of research relevant to scientific journals revealed conflicts between 'science' and 'scientists.” Owing to these conflicts, papers are often weak on objectivity and replicability. Furthermore, papers often fall short on importance, competence, intelligibility, or efficiency. Suggestions were made for editorial policies such as: (1) structured guidelines for referees, (2) open peer review, (3) blind reviews, and (4) full disclosure of data and method. Of major importance, an author's “Note to Referees” (describing the hypotheses and design, but not the results) was suggested to improve the objectivity of the ratings of importance and competence. Also, recommendations are made to authors for improving contributions to science (such as the use of multiple hypotheses) and for promoting their careers (such as using complex methods and obtuse writing).scientific journals, authors, research, editors
A new look at the pathogenesis of asthma
No full textAsthma is an inflammatory disorder of the conducting airways that has strong association with allergic sensitization. The disease is characterized by a polarized Th-2 (T-helper-2)-type T-cell response, but in general targeting this component of the disease with selective therapies has been disappointing and most therapy still relies on bronchodilators and corticosteroids rather than treating underlying disease mechanisms. With the disappointing outcomes of targeting individual Th-2 cytokines or manipulating T-cells, the time has come to re-evaluate the direction of research in this disease. A case is made that asthma has its origins in the airways themselves involving defective structural and functional behaviour of the epithelium in relation to environmental insults. Specifically, a defect in barrier function and an impaired innate immune response to viral infection may provide the substrate upon which allergic sensitization takes place. Once sensitized, the repeated allergen exposure will lead to disease persistence. These mechanisms could also be used to explain airway wall remodelling and the susceptibility of the asthmatic lung to exacerbations provoked by respiratory viruses, air pollution episodes and exposure to biologically active allergens. Variable activation of this epithelial-mesenchymal trophic unit could also lead to the emergence of different asthma phenotypes and a more targeted approach to the treatment of these. It also raises the possibility of developing treatments that increase the lung's resistance to the inhaled environment rather than concentrating all efforts on trying to suppress inflammation once it has become established.<br/
Associação entre o comportamento sedentário e o consumo de produtos ultraprocessados em adultos: estudo de base populacional
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Nutrição, Florianópolis, 2014Introdução: A melhoria das condições socioeconômicas e do aumento da escolaridade ocorrida nos últimos cinquenta anos no Brasil ocasionou mudanças nos padrões dietéticos e nutricionais da população principalmente em relação as fontes alimentícias, levando os indivíduos a um consumo elevado de alimentos e bebidas altamente processados. O consumo de produtos ultraprocessados (PUP) tem sido crescente, esses caracterizam-se por alimentos que passam por um intenso processamento industrial, com a finalidade de criar produtos "prontos para aquecer ou consumir". No Brasil, o consumo de PUP é responsável por quase um quarto do total do consumo de alimentos. Uma dieta com elevado consumo de PUP, que em sua maior parte constituem-se de quantidades bastante significativas de açúcar, sal e/ou gordura saturada e trans, pode aumentar a prevalência de obesidade e de DCNT. O consumo de PUP pode ser favorecido por comportamentos sedentários como assistir televisão ou utilizar o computador, seja porque nesses meios de comunicação existe um grande número de propagandas voltadas para esse tipo de produto, ou pela facilidade do consumo de PUP nessas situações. Objetivos: Estimar a prevalência de consumo elevado de PUP, caracterizar a distribuição do consumo segundo variáveis sociodemográficas e investigar a sua associação com variáveis indicadoras de comportamento sedentário. Metodologia: Estudo transversal de base populacional realizado com 450 adultos residentes na zona urbana da cidade de Florianópolis no estado de Santa Catarina, Sul do Brasil no ano de 2012. O consumo de PUP foi coletado através de dois R24h (o primeiro em entrevista face a face e o segundo via telefone), as informações sobre as variáveis de exposição tempo de tela (assistir televisão e utilizar o computador) durante os dias da semana e durante o final de semana e foram coletadas através de entrevista telefônica por meio de um questionário, as variáveis sociodemográficas também foram coletadas por questionário pré-testado em entrevista face a face. Os dados de alimentação foram tabulados no software NDSR e posteriormente transferidos para o software STATA 11 no qual também foram realizadas as análises estatísticas respeitando um nível de significância de 5%. As análises foram realizadas considerando o processo de amostragem por conglomerados e os respectivos pesos amostrais. Os resultados foram ajustados para variáveis sociodemográficas usando regressão logística. Resultados: Dos 450 avaliados, 41,3% deles eram sexo masculino. O consumo elevado de PUP esteve presente em 34% dos avaliados sendo este valor semelhante entre o sexo, cor da pele e renda. O consumo elevado foi significativamente maior entre os mais jovens (38,9%), solteiros (41,5%) e com maior escolaridade (38,5%) (valor-p 0,043, 0,021, 0,029 respectivamente). Na análise bruta as variáveis de comportamento sedentário que estiveram associadas ao consumo elevado de PUP foram às horas de utilização do computador tanto em dias de semana como em finais de semana (p- valor 0,021 e 0,003 respectivamente). As horas de televisão não estiveram associadas ao consumo em excesso de PUP. Foi analisada ainda uma variável que combinou o tempo total diário de televisão e computador. Para esta encontrou-se associação positiva com o consumo de PUP (valor-p=0,032). Após ajuste para variáveis sociodemográficas a única que permaneceu associada foi o tempo de utilização do computador no final de semana (odds 76% maior para =4 horas/dia do que entre aqueles com =1 hora/dia). Conclusão: Os resultados do estudo mostraram uma alta prevalência de consumo de PUP e uma associação positiva entre o comportamento sedentário e o consumo desses produtos indicando que quanto maior o tempo de tela maior o consumo de PUP. Considerando que este tipo de produto contém alto teor de sal, açúcar e gordura saturada pode contribuir para o aumento da obesidade e DCNT. Desta forma, o desafio para a saúde pública não é apenas investigar as prevalências de consumo desses produtos, mas também os motivos para o aumento do consumo de PUP, e assim definir políticas e programas de saúde abrangentes que favoreçam mudanças de comportamento na população.Abstract: Introduction: The improvement of socioeconomic conditions and increased schooling occurred in the last fifty years in Brazil caused changes in dietary and nutritional standards of the population especially regarding food sources, leading individuals to a high consumption of highly processed foods and beverages. These changes led to an increase in the prevalence of obesity as well as rise of chronic non-communicable diseases (NCDs). The consumption ultraprocessados products (PUP) has been increasing in Brazil PUP consumption accounts for almost a quarter of total food consumption. A diet with high consumption of PUP, which mostly are made up of large amounts of sugar, salt and / or saturated and trans fat may increase the prevalence of obesity and consequently several NCDs. The consumption of PUP may be favored by sedentary behaviors such as watching television or using the computer, it's because those media are a large number of advertisements aimed at this type of product, or the ease of use of PUP in these situations. Objectives: To estimate the prevalence of high intake of PUP, characterizing the distribution of consumption by sociodemographic variables and investigate their association with variables indicative of sedentary behavior. Methodology: Cross-sectional population-based study conducted with 450 adults living in the urban area of the city of Florianópolis in the state of Santa Catarina, southern Brazil in the year 2012 consumption PUP was collected through two R24h (in the first face to face interview and the second via telephone), information on exposure variables screen time (watching television and using the computer) during the weekdays and during the weekend and were collected by telephone interview using a questionnaire, the variables sociodemographic characteristics were also collected by pre-tested questionnaire administered face to face. The data were tabulated in power NDSR software and then transferred to STATA 11 software which also respecting the statistical analyzes a significance level of 5% were performed. The analyzes were performed considering the process of cluster sampling and their sampling weights. Results were adjusted for sociodemographic variables using logistic regression. Results: Of the 450 evaluated, 41.3% were male. The high consumption of PUP was present in 34% of the assessed value this being similar between gender, race and income. High consumption was significantly higher among younger (38,9%), single (41.5%) and higher education (38.5%) (p-value 0,043, 0,021, 0,029 respectively). In the crude analysis, the variables of sedentary behavior were associated with high consumption of SSP were to hours of computer use both on weekdays and on weekends (p-value 0.021 and 0.003 respectively). The hours of television were not associated with excessive consumption of PUP. A variable that combined the daily time of television and computer with four categories was also analyzed. For this positive association was found with consumption of SSP (p-value = 0.032). After adjusting for sociodemographic variables that remained associated only was the time of computer use on weekends (76% higher odds for = 4 hours / day than among those with = 1 hour / day). Conclusion: The results of the study showed a high prevalence of PUP and a positive association between sedentary behavior and the consumption of these products as more longer exposure time consumption. Since this type of product with a high content of salt, sugar and saturated fat may contribute to the rise in obesity and NCD. Thus the challenge for public health is not only to investigate the prevalence of consumption of these products plus also the reasons for the increased consumption of PUP, and so set of comprehensive health policies and programs that promote behavior change in the population
