Hafnia, an enterobacterial genus naturally resistant to colistin revealed by three susceptibility testing methods

ObjectivesTo determine the susceptibility to colistin of Hafnia alvei and Hafnia paralvei, and to compare methods for colistin resistance detection in the Hafnia genus.MethodsA collection of 25 Hafnia isolates was studied. Species were identified by using 16S rRNA gene sequencing with subsequent phylogeny analysis. Susceptibility to colistin was determined using the broth microdilution (BMD) reference method, the Phoenix automated system, the Rapid Polymyxin NP test, the Etest system and the disc diffusion method.ResultsThe collection consisted of 15 H. alvei and 10 H. paralvei isolates. Based on the 16S rRNA analysis, a close relationship of the Hafnia genus with naturally colistin-resistant enterobacterial genera (Proteus, Morganella, Providencia and Serratia) was identified. Susceptibility testing performed using the BMD method, the Phoenix automated system and the Rapid Polymyxin NP test revealed a high rate of colistin resistance (96%). Underestimation of colistin resistance using Etest strips (72%) and the disc diffusion method (0%) was observed.ConclusionsThe high rate of colistin resistance observed within the Hafnia genus and its close phylogenetic relationship with naturally colistin-resistant genera suggest that Hafnia is a naturally colistin-resistant enterobacterial genus

Conception d'un BioMicroRobot autonome

Cet article présente les avancements technologiques pour la conception théorique et pratique d'une architecture élémentaire et minimale d'un BioMicroRobot (BMR) hexapode autonome. L'autonomie minimale dépend du système de gestion des événements globaux, régionaux et locaux. Cette gestion est avant tout perçue par deux types de récepteurs : les extérocepteurs internes (vision) et ceux externes (système de repérage et de détection de l'environnement). La planification des événements dans un environnement confiné repose sur un système complexe qui incorpore un microcontrôleur d'architecture RISC, un système de propulsion bio-inspiré indépendant qui agit comme un pilote, un système d'alimentation et de communication et finalement un détecteur de proximité qui agit à titre d'extérocepteurs internes. L'avant dernière section présente un procédé de fabrication de la structure complète du BMR qui peut supporter une hiérarchie hybride à deux niveaux avec la logique floue

Mode-locked operation of a diode-pumped femtosecond Yb : SrF2 laser

International audienceFemtosecond mode-locked operation is demonstrated for the first time, to our knowledge, with a Yb:SrF2 crystal. The shortest pulse duration is 143 fs for an average power of 450 mW. The highest average power is 620 mW for a pulse duration of 173 fs. Since Yb:SrF2 corresponds to the longest-lifetime Yb-doped crystal with which the mode-locking operation has been achieved, a detailed analysis is carried out to characterize the quality of the solitonlike regime

Thermal behaviour of ytterbium-doped fluorite crystals under high power pumping

International audienceWe report an in situ thermal study of Yb-doped fluorite crystals Yb:CaF2 and Yb:SrF2 under high power pumping, with or without laser operation. The experiment combines simultaneously thermography and measurement of the thermal aberrations. This setup allows us to measure temperature gradients, thermal lens, and absorption coefficients. From these measurements, we evaluate the thermal conductivity, fractional thermal load, and thermo-optic coefficient. Great differences are observed between the lasing and non lasing regimes. Our measured thermal lenses are greater than what are expected from the thermo-optic parameters found in previous work. Based on this thermal study, we design a laser cavity operating with large output power and TEM00, leading to better performances for Yb:CaF2 than Yb:SrF2

An interactional network of genes involved in chitin synthesis in Saccharomyces cerevisiae

BACKGROUND: In S. cerevisiae the β-1,4-linked N-acetylglucosamine polymer, chitin, is synthesized by a family of 3 specialized but interacting chitin synthases encoded by CHS1, CHS2 and CHS3. Chs2p makes chitin in the primary septum, while Chs3p makes chitin in the lateral cell wall and in the bud neck, and can partially compensate for the lack of Chs2p. Chs3p requires a pathway of Bni4p, Chs4p, Chs5p, Chs6p and Chs7p for its localization and activity. Chs1p is thought to have a septum repair function after cell separation. To further explore interactions in the chitin synthase family and to find processes buffering chitin synthesis, we compiled a genetic interaction network of genes showing synthetic interactions with CHS1, CHS3 and genes involved in Chs3p localization and function and made a phenotypic analysis of their mutants. RESULTS: Using deletion mutants in CHS1, CHS3, CHS4, CHS5, CHS6, CHS7 and BNI4 in a synthetic genetic array analysis we assembled a network of 316 interactions among 163 genes. The interaction network with CHS3, CHS4, CHS5, CHS6, CHS7 or BNI4 forms a dense neighborhood, with many genes functioning in cell wall assembly or polarized secretion. Chitin levels were altered in 54 of the mutants in individually deleted genes, indicating a functional relationship between them and chitin synthesis. 32 of these mutants triggered the chitin stress response, with elevated chitin levels and a dependence on CHS3. A large fraction of the CHS1-interaction set was distinct from that of the CHS3 network, indicating broad roles for Chs1p in buffering both Chs2p function and more global cell wall robustness. CONCLUSION: Based on their interaction patterns and chitin levels we group interacting mutants into functional categories. Genes interacting with CHS3 are involved in the amelioration of cell wall defects and in septum or bud neck chitin synthesis, and we newly assign a number of genes to these functions. Our genetic analysis of genes not interacting with CHS3 indicate expanded roles for Chs4p, Chs5p and Chs6p in secretory protein trafficking and of Bni4p in bud neck organization

Association between the TNFRII 196R allele and diagnosis of rheumatoid arthritis

Tumour necrosis factor (TNF)-α plays a key role in the pathogenesis of rheumatoid arthritis (RA). It binds to two receptors, namely TNF receptor (TNFR)I and TNFRII. Several studies have suggested an association between TNFRII 196R/R genotype and RA. The objective of the present study was to evaluate the predictive value of the TNFRII 196R allele for RA diagnosis and prognosis in a cohort of patients with very early arthritis. We followed up a total of 278 patients recruited from the community, who had swelling of at least two joints that had persisted for longer than 4 weeks but had been evolving for less than 6 months, and who had not received disease-modifying antirheumatic drugs or steroid therapy. At 2 years, patients were classified according to the American College of Rheumatology criteria. All patients were genotyped with respect to TNFRII 196M/R polymorphism. Radiographs of hands and feet (read according to the modified Sharp method) and the Health Assessment Questionnaire were used to quantify structural and functional severity. The cohort of 278 patients was found to include 156 and 122 RA and non-RA patients, respectively. The TNFRII 196R allele was found to be associated with RA (P = 0.002). However, progression of radiographic severity and Health Assessment Questionnaire scores over 1 year did not differ between carriers of the 196R allele and noncarriers. Our findings suggest that the TNFRII 196R allele may be associated with RA diagnosis but that it does not predict early radiographic progression or functional severity in patients with very early, unclassified arthritis

Higher maternal leptin levels at second trimester are associated with subsequent greater gestational weight gain in late pregnancy

Background: Excessive gestational weight gain (GWG) is associated with adverse pregnancy outcomes. In non-pregnant populations, low leptin levels stimulate positive energy balance. In pregnancy, both the placenta and adipose tissue contribute to circulating leptin levels. We tested whether maternal leptin levels are associated with subsequent GWG and whether this association varies depending on stage of pregnancy and on maternal body mass index (BMI). Methods: This prospective cohort study included 675 pregnant women followed from 1st trimester until delivery. We collected anthropometric measurements, blood samples at 1st and 2nd trimester, and clinical data until delivery. Maternal leptin was measured by ELISA (Luminex technology). We classified women by BMI measured at 1st trimester: BMI < 25 kg/m2 = normal weight; 25 ≤ BMI < 30 kg/m2 = overweight; and BMI ≥ 30 kg/m2 = obese. Results: Women gained a mean of 6.7 ± 3.0 kg between 1st and 2nd trimester (mid pregnancy GWG) and 5.6 ± 2.5 kg between 2nd and the end of 3rd trimester (late pregnancy GWG). Higher 1st trimester leptin levels were associated with lower mid pregnancy GWG, but the association was no longer significant after adjusting for % body fat (%BF; β = 0.38 kg per log-leptin; SE = 0.52; P = 0.46). Higher 2nd trimester leptin levels were associated with greater late pregnancy GWG and this association remained significant after adjustment for BMI (β = 2.35; SE = 0.41; P < 0.0001) or %BF (β = 2.01; SE = 0.42; P < 0.0001). In BMI stratified analyses, higher 2nd trimester leptin levels were associated with greater late pregnancy GWG in normal weight women (β = 1.33; SE = 0.42; P = 0.002), and this association was stronger in overweight women (β = 2.85; SE = 0.94; P = 0.003 – P for interaction = 0.05). Conclusions: Our results suggest that leptin may regulate weight gain differentially at 1st versus 2nd trimester of pregnancy: at 2nd trimester, higher leptin levels were associated with greater subsequent weight gain – the opposite of its physiologic regulation in non-pregnancy – and this association was stronger in overweight women. We suspect the existence of a feed-forward signal from leptin in second half of pregnancy, stimulating a positive energy balance and leading to greater weight gain. Electronic supplementary material The online version of this article (doi:10.1186/s12884-016-0842-y) contains supplementary material, which is available to authorized users

Elimination of the Warburg effect in Chinese hamster ovary (CHO) cells improves cell phenotype as a protein production platform

Lactate is a common metabolite and is central to many important processes. One of its more prominent roles is in the Warburg effect, in which cancer cells exhibit high rates of glycolytic flux followed by secretion of lactate, even in the presence of oxygen. This fermentation of pyruvate to lactate via lactate dehydrogenase (Ldh) accompanies increased proliferation of cancer cells and several other types of rapidly proliferating cell types in immune cell activation and embryonic development. Aerobic glycolysis is also prominent in biotherapeutic protein production, where mammalian production cells often secrete high levels of lactate. The accumulation of lactate is deleterious for cell growth, viability, product formation, and quality, both directly via acidification of the media and indirectly through base addition to control culture pH. Despite a clear genetic target, efforts to eliminate lactate secretion via knockout of Ldh(s) in mammalian cells have been unsuccessful, pointing to the essentiality of Ldh mediated NAD regeneration. A wide variety of approaches have been utilized to limit lactate accumulation in culture, including knockdown or inhibition of Ldh, replacement of glucose with alternate sugars, controlled feeding strategies, and many others, however none have proven successful in eliminating the Warburg effect. We report the elimination of the Warburg effect in a CHO cell line by using CRISPR/Cas9-based engineering to simultaneously knockout enzymes responsible for lactate production and ancillary regulators. The resulting cell lines remain proliferative while consuming significantly less glucose and can be used to generate protein producing lines using standard industrial processes. In a pH-controlled fedbatch process, the Warburg null cells require minimal base addition to maintain a stable pH, allowing an extended growth phase. The knockout strategy was also successfully applied to a CHO cell line producing Rituximab, again resulting in a prolonged growth phase. Additionally, protein production was maintained, while product quality was improved with increased glycan galactosylation. Thus, CHO cells without the capacity of Warburg metabolism may be useful for engineering production cell lines with enhanced bioproduction traits

Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.

Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine