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排序方式: 共有1937条查询结果,搜索用时 31 毫秒
21.
Alison E. Murray Fabien Kenig Christian H. Fritsen Christopher P. McKay Kaelin M. Cawley Ross Edwards Emanuele Kuhn Diane M. McKnight Nathaniel E. Ostrom Vivian Peng Adrian Ponce John C. Priscu Vladimir Samarkin Ashley T. Townsend Protima Wagh Seth A. Young Pung To Yung Peter T. Doran 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(50):20626-20631
The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (−13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H2), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L−1 nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans. 相似文献
22.
Possible role of CYP2B6 genetic polymorphisms in ifosfamide‐induced encephalopathy: report of three cases
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Thomas Duflot Aude Marie‐Cardine Céline Verstuyft Bruno Filhon Tony Pereira Nathalie Massy‐Guillemant Robinson Joannidès Jérémy Bellien Fabien Lamoureux 《Fundamental & clinical pharmacology》2018,32(3):337-342
Ifosfamide (IFA) is a potent alkylating antitumoral agent, but its use is limited by neurological side effects. IFA is a racemic mixture of two enantiomeric forms, R‐IFA and S‐IFA with a stereoselective metabolism by CYP3A4 and CYP2B6, leading either to bioactive or to toxic pathways. In three consecutive cases of pediatric patients who exhibited IFA‐induced encephalopathy (IIE), genotyping of clinically relevant single‐nucleotide polymorphisms associated with decreased CYP3A4 and CYP2B6 activities was performed. Genetic investigations revealed the presence of CYP2B6 rs4803419 (C>T) in one patient while the two others carried the CYP2B6*6 allelic variant. All patients carried CYP3A4 wild‐type genotype (CYP3A4*1/*1). Because CYP2B6‐deficient alleles may be responsible for an increased conversion of S‐IFA into neurotoxic metabolites, screening for CYP2B6 polymorphisms may help to avoid IIE and improve clinical outcomes. 相似文献
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Our objective was to evaluate whether the severity of vestibular loss and old-age (>65) affect a patient's ability to benefit from training using head-position based, tongue-placed electrotactile feedback. Seventy-one chronic dizzy patients, who had reached a plateau with their conventional rehabilitation, followed six 1-h training sessions during 4 consecutive days (once on days 1 and 4, twice on days 2 and 3). They presented bilateral vestibular areflexia (BVA), bilateral vestibular losses (BVL), unilateral vestibular areflexia or unilateral vestibular losses and were divided into two age-subgroups (≤65 and >65). Posturographic assessments were performed without the device, 4 h before and after the training. Patients were tested with eyes opened and eyes closed (EC) on static and dynamic (passively tilting) platforms. The studied posturographic scores improved significantly, especially under test conditions restricting either visual or somatosensory input. This 4-h retention effect was greater in older compared to younger patients and was proportional to the degree of vestibular loss, patients with increased vestibular losses showing greater improvements. In bilateral patients, who constantly fell under dynamic-EC condition at the baseline, the therapy effect was expressed by disappearance of falls in BVL and significant prolongation in time-to-fall in BVA subgroups.Globally, our data showed that short training with head-position based, tongue-placed electrotactile biofeedback improves balance in chronic vestibulopathic patients some 16.74% beyond that achieved with standard balance physiotherapy. Further studies with longer use of this biofeedback are needed to investigate whether this approach could have long-lasting retention effect on balance and quality of life. 相似文献
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Franck Brulle Fabien Bernard Franck Vandenbulcke Damien Cuny Sylvain Dumez 《Ecotoxicology (London, England)》2014,23(3):459-471
Real-time quantitative PCR is nowadays a standard method to study gene expression variations in various samples and experimental conditions. However, to interpret results accurately, data normalization with appropriate reference genes appears to be crucial. The present study describes the identification and the validation of suitable reference genes in Brassica oleracea leaves. Expression stability of eight candidates was tested following drought and cold abiotic stresses by using three different softwares (BestKeeper, NormFinder and geNorm). Four genes (BolC.TUB6, BolC.SAND1, BolC.UBQ2 and BolC.TBP1) emerged as the most stable across the tested conditions. Further gene expression analysis of a drought- and a cold-responsive gene (BolC.DREB2A and BolC.ELIP, respectively), confirmed the stability and the reliability of the identified reference genes when used for normalization in the leaves of B. oleracea. These four genes were finally tested upon a benzene exposure and all appeared to be useful reference genes along this toxicological condition. These results provide a good starting point for future studies involving gene expression measurement on leaves of B. oleracea exposed to environmental modifications. 相似文献
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Delphine Payros Thomas Secher Michèle Boury Camille Brehin Sandrine Ménard Christel Salvador-Cartier Gabriel Cuevas-Ramos Claude Watrin Ingrid Marcq Jean-Philippe Nougayrède Damien Dubois Antoine Bedu Fabien Garnier Olivier Clermont Erick Denamur Pascale Plaisancié Vassilia Theodorou Jean Fioramonti Ma?wenn Olier Eric Oswald 《Gut microbes》2014,5(3):313-325
The neonatal gut is rapidly colonized by a newly dominant group of commensal Escherichia coli strains among which a large proportion produces a genotoxin called colibactin. In order to analyze the short- and long-term effects resulting from such evolution, we developed a rat model mimicking the natural transmission of E. coli from mothers to neonates. Genotoxic and non-genotoxic E. coli strains were equally transmitted to the offspring and stably colonized the gut across generations. DNA damage was only detected in neonates colonized with genotoxic E. coli strains. Signs of genotoxic stress such as anaphase bridges, higher occurrence of crypt fission and accelerated renewal of the mature epithelium were detected at adulthood. In addition, we observed alterations of secretory cell populations and gut epithelial barrier. Our findings illustrate how critical is the genotype of E. coli strains acquired at birth for gut homeostasis at adulthood. 相似文献
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Nidaa Mikail Khadija Benali Besma Mahida Jonathan Vigne Fabien Hyafil François Rouzet Dominique Le Guludec 《Current cardiology reports》2018,20(3):14
Purpose of review
This review analyzes recent studies evaluating the diagnostic value of 18F-FDG-PET/CT for the detection of peripheral emboli and secondary infectious foci in patients with infective endocarditis and cardiac device infections.Recent findings
Detection of extracardiac septic localizations in patients with infective endocarditis and cardiac device infections is crucial, as it may impact the diagnosis, prognosis, and therapeutic management. Recent literature substantiated the clinical usefulness of 18F-FDG-PET/CT in this setting.Summary
18F-FDG-PET/CT has proven its high diagnostic value for the detection of peripheral emboli in patients with infective endocarditis and cardiac device infections, substantially affecting patients’ outcome and treatment. A multimodal approach, combining the high sensitivity of 18F-FDG-PET/CT with morphological imaging seems promising.30.
Mayer A Ploix C Orgiazzi J Desbos A Moreira A Vidal H Monier JC Bienvenu J Fabien N 《The Journal of clinical endocrinology and metabolism》2004,89(9):4484-4488
We investigated the presence of autoantibodies (aAbs) directed against the parathyroid gland in 17 patients with spontaneous isolated acquired hypoparathyroidism. Fourteen patients with acquired hypoparathyroidism (AH) associated with type I or II autoimmune polyendocrinopathy syndrome were also tested in comparison with a control group of 68 subjects without AH, including patients with other autoimmune diseases and healthy blood donors. aAbs against parathyroid tissue were screened using an indirect immunofluorescence technique on primate parathyroid tissue and human parathyroid adenoma. aAbs against the calcium-sensing receptor (CaSR) were analyzed using an immunoblotting assay with the recombinant extracellular domain of the human CaSR as antigen. Seven of the 31 patients with AH were positive for CaSR aAbs. Five of the positive sera were obtained from the group with isolated AH. The two other positive sera were from patients with autoimmune polyendocrinopathy syndrome. The sensitivity of the immunoblotting technique was higher than that of both the radioimmunological test using the extracellular domain of the CaSR and the indirect immunofluorescence technique. There were no positive sera in the control group. In conclusion, using an immunoblotting assay, we demonstrate the presence of CaSR aAbs in about one third of the patients with isolated AH, pointing out the value of detecting such aAbs to assess the autoimmune origin of the disease. 相似文献