926 resultados para Structural Diversity of Antimicrobial Peptides


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Regular use of mouth rinses modifies the oral habitat, since bacterial populations are submitted to a high selective pressure during the treatment exercised by the active presence of the disinfectant. Mostly mouth rinses are based on the antibacterial effect of Chlorhexidine, Triclosan, essential oils and other antibacterials although other pharmaceutical characteristics can also affect their effectiveness. In this paper we compare"in vitro" the antibacterial effect of different oral rinsing solutions. Minimal Inhibitory Concentrations (MIC) and Minimal Bactericidal Concentrations (MBC) were determined as well as the kinetics of bacterial death in the presence of letal concentrations of the mouth rinses. MIC values expressed as Maximal Inhibitory Dilution (MID) of the mouth rinse ranged from 1 to 1/2048 depending on the microorganism and product, whereas Minimal Biocidal Concentration (MBC), expressed as Maximal Biocidal Dilution (MBD) ranged from 1 to 1/1024, being in general one dilution less than MIC. Maximal Biocidal Dilution is a good tool to measure the actual efficiency of mouth washing solutions. However, kinetics of death seems to be better in our work killing curves demonstrate that bacterial populations are mostly eliminated during the first minute after the contact of bacterial suspension and the mouth-washing solution. In all tested bacterial species mouth-washing solutions tested were able to reduce until suspension treated except 1 and 5

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Chlamydia and Chlamydia-related bacteria are known to infect various organisms and may cause a wide range of diseases, especially in ruminants. To gain insight into the prevalence of these bacteria in the ruminant environment, we applied a pan-Chlamydiales PCR followed by sequencing to 72 ruminant environmental samples from water, feed bunks and floors. Chlamydiales from four family-level lineages were detected indicating a high biodiversity of Chlamydiales in ruminant farms. Parachlamydiaceae were detected in all three types of environmental samples and was the most abundant family-level taxon (60%). In contrast, only one bacterium from each of the following family-level lineages was identified: Chlamydiaceae, Criblamydiaceae and Simkaniaceae. The observed high prevalence of Parachlamydiaceae in water samples may suggest water as the main source of contamination for ruminants as well as their environment due to spoilage. The absence of reported infections in the investigated ruminant farms might indicate that either detected Chlamydiales are of reduced pathogenicity or infective doses have not been reached.

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The objectives of this study were to evaluate the performance of cultivars, to quantify the variability and to estimate the genetic distances of 66 wine grape accessions in the Grape Germplasm Bank of the EMBRAPA Semi-Arid, in Juazeiro, BA, Brazil, through the characterization of discrete and continuous phenotypic variables. Multivariate statistics, such as, principal components, Tocher's optimization procedure, and the graphic of the distance, were efficient in grouping more similar genotypes, according to their phenotypic characteristics. There was no agreement in the formation of groups between continuous and discrete morpho-agronomic traits, when Tocher's optimization procedure was used. Discrete variables allowed the separation of Vitis vinifera and hybrids in different groups. Significant positive correlations were observed between weight, length and width of bunches, and a negative correlation between titratable acidity and TSS/TTA. The major part (84.12%) of the total variation present in the original data was explained by the four principal components. The results revealed little variability between wine grape accessions in the Grape Germplasm Bank of Embrapa Semi-Arid.

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[cat] El comerç internacional en béns agrícoles té el potencial d'accelerar la transformació estructural dels països amb baixa productivitat agrícola perquè els dóna la possiblitat d'importar aliments. L'objectiu d'aquest article és estudiar l'importància del comerç internacional en aquest context a través dels exemples de Corea del Sud i el Regne Unit. Per fer l'anàlisi, introdueixo comerç internacional en un model de creixement neoclàssicc amb dos sectors, agricultura i no-agricultura. Una característica clau del model és la baixa elasticitat-ingrés del bé agrícola.

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[cat] El comerç internacional en béns agrícoles té el potencial d'accelerar la transformació estructural dels països amb baixa productivitat agrícola perquè els dóna la possiblitat d'importar aliments. L'objectiu d'aquest article és estudiar l'importància del comerç internacional en aquest context a través dels exemples de Corea del Sud i el Regne Unit. Per fer l'anàlisi, introdueixo comerç internacional en un model de creixement neoclàssicc amb dos sectors, agricultura i no-agricultura. Una característica clau del model és la baixa elasticitat-ingrés del bé agrícola.

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The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.

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In the Arabidopsis thaliana genome, over 1000 putative genes encoding small, presumably secreted, signalling peptides can be recognized. However, a major obstacle in identifying the function of genes encoding small signalling peptides is the limited number of available loss-of-function mutants. To overcome this, a promising new tool, antagonistic peptide technology, was recently developed. Here, this antagonistic peptide technology was tested on selected CLE peptides and the related IDA peptide and its usefulness in the context of studies of peptide function discussed. Based on the analyses, it was concluded that the antagonistic peptide approach is not the ultimate means to overcome redundancy or lack of loss-of-function lines. However, information collected using antagonistic peptide approaches (in the broad sense) can be very useful, but these approaches do not work in all cases and require a deep insight on the interaction between the ligand and its receptor to be successful. This, as well as peptide ligand structure considerations, should be taken into account before ordering a wide range of synthetic peptide variants and/or generating transgenic plants.

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Fish eggs are associated with microbes, whose roles range from mutualism to parasitism. Recent laboratory experiments have shown that the taxonomic composition of associated microbial communities on the egg influences embryonic development. Host genetics also plays an important role in determining the consequences for embryonic growth and survival in this interaction. Moreover, it has been found that the importance of host genetics increases during embryogenesis. These findings suggest that during embryogenesis, the host increasingly influences the composition of its associated microbial community. However, little is known about the composition of microbial communities associated with naturally spawned eggs in the wild. We sampled fertilized whitefish eggs (Coregonus spp.) of different developmental stages from six sub-Alpine lakes and used a universal primer pair and 454 pyrosequencing in order to describe the taxonomic composition of egg-associated bacterial communities. We found bacterial communities on early embryos to be very diverse and to resemble the bacterial composition of the surrounding water environment. The bacterial communities on late embryos were significantly less diverse than on early embryos and displayed a clear shift in taxonomic composition that corresponded poorly with the bacterial composition of the surrounding water environment. The main bacterial components on whitefish eggs in this study were Proteobacteria, Actinobacteria, and Firmicutes, while the five most common families were Leuconostocaceae, Streptococcaceae, Comamonadaceae, Oxalobacteraceae and Moraxellaceae. Their putative relationships with the host are discussed. We conclude that natural symbiotic bacterial communities become more specialized during embryogenesis because of specific interactions with their embryo host.

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A review of health sciences literature shows a substantial increase in qualitative publications. This work incorporates a certain number of research quality guidelines. We present the results of the Alceste® lexicometric analysis, which includes 133 quality grids for qualitative research covering five disciplinary fields of the health sciences: medicine and epidemiology, public health and health education, nursing, health sociology and anthropology, psychiatry and psychology. This analysis helped to cross-check the disciplinary fields with the various objectives assigned to the different criteria in the grids examined. The results obtained with Alceste® show the variability of the objectives sought by the authors of the guidelines. These discrepancies are not directly associated to disciplinary fields, and appear to be more closely linked to different qualitative research conceptualizations within the disciplines, and with essential qualitative research validation criteria. These conceptualizations must be clarified to help users better understand the objectives targeted by the grids, and promote more appreciation for qualitative research in the health sciences.

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Purpose: To assess the feasibility of a method based on microwave spectrometry to detect structural distortions of metallic stents in open air conditions and envisage the prospects of this approach toward possible medical applicability for the evaluation of implanted stents. Methods: Microwave absorbance spectra between 2.0 and 18.0 GHz were acquired in open air for the characterization of a set of commercial stents using a specifically design setup. Rotating each sample over 360º, 2D absorbance diagrams were generated as a function of frequency and rotation angle. To check our approach for detecting changes in stent length (fracture) and diameter (recoil), two specific tests were performed in open air. Finally, with a few adjustments, this same system provides 2D absorbance diagrams of stents immersed in a water-based phantom, this time over a bandwidth ranging from 0.2 to 1.8 GHz. Results: The authors show that metallic stents exhibit characteristic resonant frequencies in their microwave absorbance spectra in open air which depend on their length and, as a result, may reflect the occurrence of structural distortions. These resonances can be understood considering that such devices behave like dipole antennas in terms of microwave scattering. From fracture tests, the authors infer that microwave spectrometry provides signs of presence of Type I to Type IV stent fractures and allows in particular a quantitative evaluation of Type III and Type IV fractures. Recoil tests show that microwave spectrometry seems able to provide some quantitative assessment of diametrical shrinkage, but only if it involves longitudinal shortening. Finally, the authors observe that the resonant frequencies of stents placed inside the phantom shift down with respect to the corresponding open air frequencies, as it should be expected considering the increase of dielectric permittivity from air to water. Conclusions: The evaluation of stent resonant frequencies provided by microwave spectrometry allows detection and some quantitative assessment of stent fracture and recoil in open air conditions. Resonances of stents immersed in water can be also detected and their characteristic frequencies are in good agreement with theoretical estimates. Although these are promising results, further verifica tion in a more relevant phantom is required in order to foresee the real potential of this approach.

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The taxonomic composition of egg-associated microbial communities can play a crucial role in the development of fish embryos. In response, hosts increasingly influence the composition of their associated microbial communities during embryogenesis, as concluded from recent field studies and laboratory experiments. However, little is known about the taxonomic composition and the diversity of egg-associated microbial communities within ecosystems; e.g., river networks. We sampled late embryonic stages of naturally spawned brown trout at nine locations within two different river networks and applied 16S rRNA pyrosequencing to describe their bacterial communities. We found no evidence for a significant isolation-by-distance effect on the composition of bacterial communities, and no association between neutral genetic divergence of fish host (based on 11 microsatellites) and phylogenetic distances of the composition of their associated bacterial communities. We characterized core bacterial communities on brown trout eggs and compared them to corresponding water samples with regard to bacterial composition and its presumptive function. Bacterial diversity was positively correlated with water temperature at the spawning locations. We discuss this finding in the context of the increased water temperatures that have been recorded during the last 25 years in the study area.

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The Chlamydiales order is composed of nine families of strictly intracellular bacteria. Among them, Chlamydia trachomatis, C. pneumoniae, and C. psittaci are established human pathogens, whereas Waddlia chondrophila and Parachlamydia acanthamoebae have emerged as new pathogens in humans. However, despite their medical importance, their biodiversity and ecology remain to be studied. Even if arthropods and, particularly, ticks are well known to be vectors of numerous infectious agents such as viruses and bacteria, virtually nothing is known about ticks and chlamydia. This study investigated the prevalence of Chlamydiae in ticks. Specifically, 62,889 Ixodes ricinus ticks, consolidated into 8,534 pools, were sampled in 172 collection sites throughout Switzerland and were investigated using pan-Chlamydiales quantitative PCR (qPCR) for the presence of Chlamydiales DNA. Among the pools, 543 (6.4%) gave positive results and the estimated prevalence in individual ticks was 0.89%. Among those pools with positive results, we obtained 16S rRNA sequences for 359 samples, allowing classification of Chlamydiales DNA at the family level. A high level of biodiversity was observed, since six of the nine families belonging to the Chlamydiales order were detected. Those most common were Parachlamydiaceae (33.1%) and Rhabdochlamydiaceae (29.2%). "Unclassified Chlamydiales" (31.8%) were also often detected. Thanks to the huge amount of Chlamydiales DNA recovered from ticks, this report opens up new perspectives on further work focusing on whole-genome sequencing to increase our knowledge about Chlamydiales biodiversity. This report of an epidemiological study also demonstrates the presence of Chlamydia-related bacteria within Ixodes ricinus ticks and suggests a role for ticks in the transmission of and as a reservoir for these emerging pathogenic Chlamydia-related bacteria.

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PURPOSE: Needs assessment is recognized to be a key element of mental health care. Patients tend to present heterogeneous profiles of needs. However, there is no consensus in previous research about how patients' needs are organized. This study investigates both general and specific dimensions of patients' needs for care. METHODS: Patients' needs were assessed with ELADEB, an 18-domain self-report scale. The use of a self-assessment scale represents a unique way of obtaining patients' perceptions. A patient-centered psychiatric practice facilitates empowerment as it is based on the patients' personal motivations, needs, and wants. Four seventy-one patients' profiles were analyzed through exploratory factor analysis. RESULTS: A four-factor bifactor model, including one general factor and three specific factors of needs, was most adequate. Specific factors were (a) "finances" and "administrative tasks"; (b) "transports," "public places," "self-care," "housework," and "food"; and (c) "family," "children," "intimate relationships," and "friendship." CONCLUSION: As revealed by the general factor, patients expressing urgent needs in some domains are also more susceptible to report urgent needs in several other domains. This general factor relates to high versus low utilizers of public mental healthcare. Patients also present specific needs in life domains, which are organized in three dimensions: management, functional disabilities, and familial and interpersonal relationships. These dimensions relate to the different types of existing social support described in the literature.