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排序方式: 共有160条查询结果,搜索用时 46 毫秒
81.
Badreddine Douzi Eric Durand C��dric Bernard S��bastien Alphonse Christian Cambillau Alain Filloux Mariella Tegoni Rom�� Voulhoux 《The Journal of biological chemistry》2009,284(50):34580-34589
Gram-negative bacteria use the sophisticated type II secretion system (T2SS) to secrete a large number of exoproteins into the extracellular environment. Five proteins of the T2SS, the pseudopilins GspG-H-I-J-K, are proposed to assemble into a pseudopilus involved in the extrusion of the substrate through the outer membrane channel. Recent structural data have suggested that the three pseudopilins GspI-J-K are organized in a trimeric complex located at the tip of the GspG-containing pseudopilus. In the present work we combined two biochemical techniques to investigate the protein-protein interaction network between the five Pseudomonas aeruginosa Xcp pseudopilins. The soluble domains of XcpT-U-V-W-X (respectively homologous to GspG-H-I-J-K) were purified, and the interactions were tested by surface plasmon resonance and affinity co-purification in all possible combinations. We found an XcpVI-WJ-XK complex, which demonstrates that the crystallized trimeric complex also exists in the P. aeruginosa T2SS. Interestingly, our systematic approach revealed an additional and yet uncharacterized interaction between XcpUH and XcpWJ. This observation suggested the existence of a quaternary, rather than ternary, complex (XcpUH-VI-WJ-XK) at the tip of the pseudopilus. The assembly of this quaternary complex was further demonstrated by co-purification using affinity chromatography. Moreover, by testing various combinations of pseudopilins by surface plasmon resonance and affinity chromatography, we were able to dissect the different possible successive steps occurring during the formation of the quaternary complex. We propose a model in which XcpVI is the nucleator that first binds XcpXK and XcpWJ at different sites. Then the ternary complex recruits XcpUH through a direct interaction with XcpWJ. 相似文献
82.
83.
Anna E. M. F. M. Oliveira Jonatas L. Duarte Jesus R. R. Amado Rodrigo A. S. Cruz Clarice F. Rocha Raimundo N. P. Souto Ricardo M. A. Ferreira Karen Santos Edemilson C. da Concei??o Leandra A. R. de Oliveira Alphonse Kelecom Caio P. Fernandes José C. T. Carvalho 《PloS one》2016,11(1)
Pterodon emarginatus Vogel is a Brazilian species that belongs to the family Fabaceae, popularly known as sucupira. Its oil has several biological activities, including potent larvicidal property against Aedes aegypti. This insect is the vector of dengue, a tropical disease that has been considered a critical health problem in developing countries, such as Brazil. Most of dengue control methods involve larvicidal agents suspended or diluted in water and making active lipophilic natural products available is therefore considered a technological challenge. In this context, nanoemulsions appear as viable alternatives to solve this major problem. The present study describes the development of a novel nanoemulsion with larvicidal activity against A. aegypti along with the required Hydrophile Lipophile Balance determination of this oil. It was suggested that the mechanism of action might involve reversible inhibition of acetylcholinesterase and our results also suggest that the P. emarginatus nanoemulsion is not toxic for mammals. Thus, it contributes significantly to alternative integrative practices of dengue control, as well as to develop sucupira based nanoproducts for application in aqueous media. 相似文献
84.
85.
Njamnshi AK Seke Etet PF Perrig S Acho A Funsah JY Mumba D Muyembe JJ Kristensson K Bentivoglio M 《PLoS neglected tropical diseases》2012,6(2):e1525
Background
Human African trypanosomiasis (HAT) or sleeping sickness leads to a complex neuropsychiatric syndrome with characteristic sleep alterations. Current division into a first, hemolymphatic stage and second, meningoencephalitic stage is primarily based on the detection of white blood cells and/or trypanosomes in the cerebrospinal fluid. The validity of this criterion is, however, debated, and novel laboratory biomarkers are under study. Objective clinical HAT evaluation and monitoring is therefore needed. Polysomnography has effectively documented sleep-wake disturbances during HAT, but could be difficult to apply as routine technology in field work. The non-invasive, cost-effective technique of actigraphy has been widely validated as a tool for the ambulatory evaluation of sleep disturbances. In this pilot study, actigraphy was applied to the clinical assessment of HAT patients.Methods/Principal Findings
Actigraphy was recorded in patients infected by Trypanosoma brucei gambiense, and age- and sex-matched control subjects. Simultaneous nocturnal polysomnography was also performed in the patients. Nine patients, including one child, were analyzed at admission and two of them also during specific treatment. Parameters, analyzed with user-friendly software, included sleep time evaluated from rest-activity signals, rest-activity rhythm waveform and characteristics. The findings showed sleep-wake alterations of various degrees of severity, which in some patients did not parallel white blood cell counts in the cerebrospinal fluid. Actigraphic recording also showed improvement of the analyzed parameters after treatment initiation. Nocturnal polysomnography showed alterations of sleep time closely corresponding to those derived from actigraphy.Conclusions/Significance
The data indicate that actigraphy can be an interesting tool for HAT evaluation, providing valuable clinical information through simple technology, well suited also for long-term follow-up. Actigraphy could therefore objectively contribute to the clinical assessment of HAT patients. This method could be incorporated into a clinical scoring system adapted to HAT to be used in the evaluation of novel treatments and laboratory biomarkers. 相似文献86.
87.
Martin W. Bratschi Miriam Bolz Jacques C. Minyem Leticia Grize Fidèle G. Wantong Sarah Kerber Earnest Njih Tabah Marie-Thérèse Ruf Ferdinand Mou Djeunga Noumen Alphonse Um Boock Gerd Pluschke 《PLoS neglected tropical diseases》2013,7(6)
Buruli ulcer (BU), a neglected tropical disease of the skin, caused by Mycobacterium ulcerans, occurs most frequently in children in West Africa. Risk factors for BU include proximity to slow flowing water, poor wound care and not wearing protective clothing. Man-made alterations of the environment have been suggested to lead to increased BU incidence. M. ulcerans DNA has been detected in the environment, water bugs and recently also in mosquitoes. Despite these findings, the mode of transmission of BU remains poorly understood and both transmission by insects or direct inoculation from contaminated environment have been suggested. Here, we investigated the BU epidemiology in the Mapé basin of Cameroon where the damming of the Mapé River since 1988 is believed to have increased the incidence of BU. Through a house-by-house survey in spring 2010, which also examined the local population for leprosy and yaws, and continued surveillance thereafter, we identified, till June 2012, altogether 88 RT-PCR positive cases of BU. We found that the age adjusted cumulative incidence of BU was highest in young teenagers and in individuals above the age of 50 and that very young children (<5) were underrepresented among cases. BU lesions clustered around the ankles and at the back of the elbows. This pattern neither matches any of the published mosquito biting site patterns, nor the published distribution of small skin injuries in children, where lesions on the knees are much more frequent. The option of multiple modes of transmission should thus be considered. Analyzing the geographic distribution of cases in the Mapé Dam area revealed a closer association with the Mbam River than with the artificial lake. 相似文献
88.
Godet AN Guergnon J Galioot A Falanga PB Colle JH Cayla X Garcia A 《Médecine sciences : M/S》2011,27(12):1106-1111
Protein phosphatase 2A (PP2A) is a large family of holoenzymes that comprises 1% of total cellular proteins and accounts for the majority of Ser/Thr phosphatase activity in eukaryotic cells. PP2A proteins are made of a core dimer, composed of a catalytic (C) subunit and a structural (A) subunit, in association with a third variable -regulatory (B) subunit. Although initially considered as a constitutive housekeeping enzyme, PP2A is indeed highly regulated by post-translational modifications of its catalytic subunit or by the identity of a regulatory type B subunit, which determines substrate specificity, subcellular localization and enzymatic activity of a defined holoenzyme. During the two last decades, multiple studies of structural and functional regulation of PP2A holoenzymes by viral proteins led to the identification of critical pathways for both viral biology and tumorigenesis. To date a dozen of different viruses (ADN/ARN or retrovirus) have been identified that encode viral proteins associated to PP2A. In this review, we analyze a biological strategy, used by various viruses based on the targeting of PP2A enzymes by viral proteins, in order to specifically deregulate cellular pathways of their hosts. The impact of such PP2A targeting for biomedical search, and in further therapeutic developments against cancer, will also be discussed. 相似文献
89.
Konaté AT Yaro JB Ouédraogo AZ Diarra A Gansané A Soulama I Kangoyé DT Kaboré Y Ouédraogo E Ouédraogo A Tiono AB Ouédraogo IN Chandramohan D Cousens S Milligan PJ Sirima SB Greenwood BM Diallo DA 《PloS one》2011,6(8):e23391
Background
Interventions that reduce exposure to malaria infection may lead to delayed malaria morbidity and mortality. We investigated whether intermittent preventive treatment of malaria in children (IPTc) was associated with an increase in the incidence of malaria after cessation of the intervention.Methods
An individually randomised, trial of IPTc, comparing three courses of sulphadoxine pyrimethamine (SP) plus amodiaquine (AQ) with placebos was implemented in children aged 3–59 months during the 2008 malaria transmission season in Burkina Faso. All children in the trial were given a long lasting insecticide treated net; 1509 children received SP+AQ and 1505 received placebos. Passive surveillance for malaria was maintained until the end of the subsequent malaria transmission season in 2009, and active surveillance for malaria infection, anaemia and malnutrition was conducted.Results
On thousand, four hundred and sixteen children (93.8%) and 1399 children (93.0%) initially enrolled in the intervention and control arms of the trial respectively were followed during the 2009 malaria transmission season. During the period July 2009 to November 2009, incidence rates of clinical malaria were 3.84 (95%CI; 3.67–4.02) and 3.45 (95%CI; 3.29–3.62) episodes per child during the follow up period in children who had previously received IPT or placebos, indicating a small increase in risk for children in the former intervention arm (IRR = 1.12; 95%CI 1.04–1.20) (P = 0.003). Children who had received SP+AQ had a lower prevalence of malaria infection (adjusted PR: 0.88 95%CI: 0.79–0.98) (P = 0.04) but they had a higher parasite density (P = 0.001) if they were infected. There was no evidence that the risks of moderately severe anaemia (Hb<8 g/dL), wasting, stunting, or of being underweight in children differed between treatment arms.Conclusion
IPT with SP+AQ was associated with a small increase in the incidence of clinical malaria in the subsequent malaria transmission season.Trial Registration
ClinicalTrials.gov NCT00738946相似文献90.
Konaté AT Yaro JB Ouédraogo AZ Diarra A Gansané A Soulama I Kangoyé DT Kaboré Y Ouédraogo E Ouédraogo A Tiono AB Ouédraogo IN Chandramohan D Cousens S Milligan PJ Sirima SB Greenwood B Diallo DA 《PLoS medicine》2011,8(2):e1000408