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101.
Monica Moschioni Morena Lo Sapio Giovanni Crisafulli Giulia Torricelli Silvia Guidotti Alessandro Muzzi Michèle A. Barocchi Claudio Donati 《PloS one》2013,8(4)
Multi-Locus Sequence Typing (MLST) of Streptococcus pneumoniae is based on the sequence of seven housekeeping gene fragments. The analysis of MLST allelic profiles by eBURST allows the grouping of genetically related strains into Clonal Complexes (CCs) including those genotypes with a common descent from a predicted ancestor. However, the increasing use of MLST to characterize S. pneumoniae strains has led to the identification of a large number of new Sequence Types (STs) causing the merger of formerly distinct lineages into larger CCs. An example of this is the CC156, displaying a high level of complexity and including strains with allelic profiles differing in all seven of the MLST loci, capsular type and the presence of the Pilus Islet-1 (PI-1). Detailed analysis of the CC156 indicates that the identification of new STs, such as ST4945, induced the merging of formerly distinct clonal complexes. In order to discriminate the strain diversity within CC156, a recently developed typing schema, 96-MLST, was used to analyse 66 strains representative of 41 different STs. Analysis of allelic profiles by hierarchical clustering and a minimum spanning tree identified ten genetically distinct evolutionary lineages. Similar results were obtained by phylogenetic analysis on the concatenated sequences with different methods. The identified lineages are homogenous in capsular type and PI-1 presence. ST4945 strains were unequivocally assigned to one of the lineages. In conclusion, the identification of new STs through an exhaustive analysis of pneumococcal strains from various laboratories has highlighted that potentially unrelated subgroups can be grouped into a single CC by eBURST. The analysis of additional loci, such as those included in the 96-MLST schema, will be necessary to accurately discriminate the clonal evolution of the pneumococcal population. 相似文献
102.
Shao-Fu Huang Lun-Jou Lo 《Computer methods in biomechanics and biomedical engineering》2016,19(16):1704-1713
This study investigates the biomechanical interaction of different mini-plate fixation types (shapes/sizes and patterns) with segmental advancement levels on the Le Fort I osteotomy using the non-linear finite element (FE) approach. Nine models were generated under a standard 1-piece LeFort I osteotomy for advancement with 3, 6 and 9 mm distances and four mini-plates with three fixation patterns including LL, LI, and II patterns placed on the maxillae models by integrating computed tomography images and computer-aided design system. The axial and oblique occlusal forces were 250 N applied to each premolar/molar and 125 N applied at 30° inclination to the tooth long axis and from palatal to buccal, respectively. The relative micro-movement values between the two maxillary bone segments and maximum mini-plate stress increased obviously with maxilla advancement increment and the increasing trend can be fitted by exponential curve. The corresponding values in II mini-plate fixation presented apparently high values in all simulated cases. The mini-plate stress concentration locations were found at the bending regions to increase high fracture risk. The mini-plate yield strength can be mapped to a critical (limited) advancement for three types of fixations for safe consideration. This study concluded that L-shaped mini-plates with lateral fixation are recommended to provide better stability. The risk for mini-plate fracture and bone relapse increases when maxillary advancement is larger than a critical value of 5 mm in the Le Fort I osteotomy. 相似文献
103.
Abstract. Throughout the history of studies on cellulose digestion in termites, carboxymethyl-cellulose has been preferably used as a substrate for measuring cellulase activity in termites due to its high solubility. However, carboxymethyl-cellulose degradation is not directly related to digestibility of naturally occurring cellulose because many noncellulolytic organisms can also hydrolyse carboxymethyl-cellulose. To address this issue, a comparative study of microcrystalline cellulose digestion is performed in diverse xylophagous termites, using gut homogenates. For those termites harbouring gut flagellates , the majority of crystalline cellulose appears to be digested in the hindgut, both in the supernatant and the pellet. For Nasutitermes takasagoensis , a termite free of gut flagellates, crystalline cellulose is degraded primarily in the midgut supernatant, and partially in the pellet of the hindgut. The fungus-growing termite Odontotermes formosanus , which also does not possess intestinal flagellates, shows only a trace of crystalline cellulose hydrolysis throughout the gut. Comparison of levels of activity against crystalline cellulose with previously reported levels of activity against carboxymethyl-cellulose in the gut of each termite reveals significant differences between these activities. The results suggest that the hindgut flagellates produce commonly cellobiohydrolases in addition to endo-β-1,4-glucanases, which presumably act synergistically to digest cellulose. Preliminary evidence for the involvement of bacteria in the cellulose digestion of N. takasagoensis is also found. 相似文献
104.
Leflaive J Céréghino R Danger M Lacroix G Ten-Hage L 《Journal of microbiological methods》2005,62(1):89-102
The use of community-level physiological profiles obtained with Biolog microplates is widely employed to consider the functional diversity of bacterial communities. Biolog produces a great amount of data which analysis has been the subject of many studies. In most cases, after some transformations, these data were investigated with classical multivariate analyses. Here we provided an alternative to this method, that is the use of an artificial intelligence technique, the Self-Organizing Maps (SOM, unsupervised neural network). We used data from a microcosm study of algae-associated bacterial communities placed in various nutritive conditions. Analyses were carried out on the net absorbances at two incubation times for each substrates and on the chemical guild categorization of the total bacterial activity. Compared to Principal Components Analysis and cluster analysis, SOM appeared as a valuable tool for community classification, and to establish clear relationships between clusters of bacterial communities and sole-carbon sources utilization. Specifically, SOM offered a clear bidimensional projection of a relatively large volume of data and were easier to interpret than plots commonly obtained with multivariate analyses. They would be recommended to pattern the temporal evolution of communities' functional diversity. 相似文献
105.
Dengqun Liu Megan D Radyk Rebecca L Cunningham Joseph Burclaff Greg Sibbel Hei‐Yong G Lo Valerie Blanc Nicholas O Davidson Zhen‐Ning Wang Jason C Mills 《The EMBO journal》2018,37(7)
In 1900, Adami speculated that a sequence of context‐independent energetic and structural changes governed the reversion of differentiated cells to a proliferative, regenerative state. Accordingly, we show here that differentiated cells in diverse organs become proliferative via a shared program. Metaplasia‐inducing injury caused both gastric chief and pancreatic acinar cells to decrease mTORC1 activity and massively upregulate lysosomes/autophagosomes; then increase damage associated metaplastic genes such as Sox9; and finally reactivate mTORC1 and re‐enter the cell cycle. Blocking mTORC1 permitted autophagy and metaplastic gene induction but blocked cell cycle re‐entry at S‐phase. In kidney and liver regeneration and in human gastric metaplasia, mTORC1 also correlated with proliferation. In lysosome‐defective Gnptab?/? mice, both metaplasia‐associated gene expression changes and mTORC1‐mediated proliferation were deficient in pancreas and stomach. Our findings indicate differentiated cells become proliferative using a sequential program with intervening checkpoints: (i) differentiated cell structure degradation; (ii) metaplasia‐ or progenitor‐associated gene induction; (iii) cell cycle re‐entry. We propose this program, which we term “paligenosis”, is a fundamental process, like apoptosis, available to differentiated cells to fuel regeneration following injury. 相似文献
106.
Marco Barbero Roberto Gatti Loredana Lo Conte Fiona Macmillan Fiona Coutts Roberto MerlettiAuthor vitae 《Journal of electromyography and kinesiology》2011,21(5):827-833
The identification of the motor unit (MU) innervation zone (IZ) using surface electromyographic (sEMG) signals detected on the skin with a linear array or a matrix of electrodes has been recently proposed in the literature. However, an analysis of the reliability of this procedure and, therefore, of the suitability of the sEMG signals for this purpose has not been reported.The purpose of this work is to describe the intra and inter-rater reliability and the suitability of surface EMG in locating the innervation zone of the upper trapezius muscle.Two operators were trained on electrode matrix positioning and sEMG signal analysis. Ten healthy subjects, instructed to perform a series of isometric contractions of the upper trapezius muscle participated in the study. The two operators collected sEMG signals and then independently estimated the IZ location through visual analysis.Results showed an almost perfect agreement for intra-rater and inter-rater reliability. The constancy of IZ location could be affected by the factors reflecting the population of active MUs and their IZs, including: the contraction intensity, the acquisition period analyzed, the contraction repetition. In almost all cases the IZ location shift due to these factors did not exceed 4 mm. Results generalization to other muscles should be made with caution. 相似文献
107.
Bonhomme J Le Goff L Lemée V Gargala G Ballet JJ Favennec L 《Parasitology international》2011,60(3):327-330
The intestinal protozoan Giardia duodenalis includes 2 genetically distinct assemblages, A and B, which are responsible for human infections. Little is known so far on the genotypes of G. duodenalis human isolates in France. The present characterization of 19 French clinical isolates was aimed at determining their genotype patterns and associations with clinical symptoms, and in vivo metronidazole resistance, respectively. Based on both triose-phosphate isomerase (tpi) and β-giardin (bg) gene sequences, twelve isolates were identified as assemblage A, and 7 as assemblage B for the 2 gene loci. Sub-genotyping heterogeneities were observed in 15/19 isolates attributed to either A or B assemblage. They include frequent mismatches and intra-assemblage discordances and mixed positions, which were found more frequently in tpi than in bg sequences, and in assemblage B than in assemblage A sequences. No association was found between sub-genotypes, clinical symptoms and metronidazole sensitivity. Present data underline the need for improvements in the standardization of G. duodenalis multilocus genotyping approach for further molecular epidemiologic studies of giardiasis. 相似文献
108.
Hepatitis C virus core protein interacts with the cytoplasmic tail of lymphotoxin-beta receptor. 总被引:20,自引:2,他引:20 下载免费PDF全文
M Matsumoto T Y Hsieh N Zhu T VanArsdale S B Hwang K S Jeng A E Gorbalenya S Y Lo J H Ou C F Ware M M Lai 《Journal of virology》1997,71(2):1301-1309
Hepatitis C virus (HCV) core protein is a multifunctional protein. We examined whether it can interact with cellular proteins, thus contributing to viral pathogenesis. Using the HCV core protein as a bait to screen a human liver cDNA library in a yeast two-hybrid screening system, we have isolated several positive clones encoding cellular proteins that interact with the HCV core protein. Interestingly, more than half of these clones encode the cytoplasmic domain of lymphotoxin-beta receptor (LT betaR), which is a member of the tumor necrosis factor receptor family. Their binding was confirmed by in vitro glutathione S-transferase fusion protein binding assay and protein-protein blotting assay to be direct and specific. The binding sites were mapped within a 58-amino-acid region of the cytoplasmic tail of LT betaR. The binding site in the HCV core protein was localized within amino acid residues 36 to 91 from the N terminus, corresponding to the hydrophilic region of the protein. In mammalian cells, the core protein was found to be associated with the membrane-bound LT betaR. Since the LT betaR is involved in germinal center formation and developmental regulation of peripheral lymphoid organs, lymph node development, and apoptotic signaling, the binding of HCV core protein to LT betaR suggests the possibility that this viral protein has an immunomodulating function and may explain the mechanism of viral persistence and pathogenesis of HCV. 相似文献
109.
Edmond Pui-Hang Choi Janet Yuen-Ha Wong Herman Hay-Ming Lo Wendy Wong Jasmine Hin-Man Chio Daniel Yee-Tak Fong 《PloS one》2016,11(11)
Dating applications (apps) on smartphones have become increasingly popular. The aim of this study was to explore the association between the use of dating apps and risky sexual behaviours. Data were collected in four university campuses in Hong Kong. Subjects completed a structured questionnaire asking about the use of dating apps, sexual behaviours, and sociodemographics. Multiple linear and logistics regressions were used to explore factors associated with sexual risk behaviours. Six hundred sixty-six subjects were included in the data analysis. Factors associated with having unprotected sexual intercourse with more lifetime sexual partners included use of dating apps (β = 0.93, p<0.01), having one’s first sexual intercourse before 16 years of age (β = 1.74, p<0.01), being older (β = 0.4, p<0.01), currently being in a relationship (= 0.69, p<0.05), having a monthly income at least HKD$5,000 (β = 1.34, p<0.01), being a current smoker (β = 1.52, p<0.01), and being a current drinker (β = 0.7, p<0.01). The results of a multiple logistic regression analysis found that users of dating apps (adjust odds ratio: 0.52, p<0.05) and current drinkers (adjust odds ratio: 0.40, p<0.01) were less likely to have consistent condom use. Users of dating apps (adjust odds ratio: 1.93, p<0.05), bisexual/homosexual subjects (adjust odds ratio: 2.57, p<0.01) and female subjects (adjust odds ratio: 2.00, p<0.05) were more likely not to have used condoms the last time they had sexual intercourse. The present study found a robust association between using dating apps and sexual risk behaviours, suggesting that app users had greater sexual risks. Interventions that can target app users so that they can stay safe when seeking sexual partners through dating apps should be developed. 相似文献
110.
Cornille Fabrice Martin Loïc Lenoir Christine Cussac Didier Roques Bernard P. Fournié-Zaluski Marie-Claude 《International journal of peptide research and therapeutics》1997,4(4-6):207-212
Summary The light chain of tetanus neurotoxin (TeNTL chain) has been shown to be endowed with zine endopeptidase activity, selectively
directed towards the Gln76-Phe77 bond of synaptobrevin, a vesicle-associated membrane protein critically involved in neuroexocytosis. In previous reports,
truncations at the NH2- and COOH-terminus of synaptobrevin have shown that the sequence 39–88 of synaptobrevin is the minimum substrate of TeNT,
suggesting either the requirement of a well-defined three-dimensional structure of synaptobrevin or a role in the mechanism
of substrate hydrolysis for residues distal from the cleavage site. In this study, the addition of NH2- and COOH-terminal peptides of synaptobrevin, S 27–55 (S1) and S 82–93 (S2), to the synaptobrevin fragment S 56–81 allowed the cleavage of this latter peptide by TeNT to occur. This appears to result
from an activation process mediated by the simultaneous binding of S1 and S2 with complementary sites present on TeNT as shown by surface plasmon resonance experiments. All these results favor an exosite-controlled
hydrolysis of synaptobrevin by TeNT probably involving a conformational change of the toxin. This could accound for the high
degree of substrate specificity of TeNT and, probably, botulinum neurotoxins. 相似文献