Quantum control of a cat qubit with bit-flip times exceeding ten seconds.

Quantum bits (qubits) are prone to several types of error as the result of uncontrolled interactions with their environment. Common strategies to correct these errors are based on architectures of qubits involving daunting hardware overheads1. One possible solution is to build qubits that are inherently protected against certain types of error, so the overhead required to correct the remaining errors is greatly reduced2-7. However, this strategy relies on one condition: any quantum manipulations of the qubit must not break the protection that has been so carefully engineered5,8. A type of qubit known as a cat qubit is encoded in the manifold of metastable states of a quantum dynamical system, and thereby acquires continuous and autonomous protection against bit-flips. Here, in a superconducting-circuit experiment, we implemented a cat qubit with bit-flip times exceeding 10 s. This is an improvement of four orders of magnitude over previously published cat-qubit implementations. We prepared and imaged quantum superposition states, and measured phase-flip times greater than 490 ns. Most importantly, we controlled the phase of these quantum superpositions without breaking the bit-flip protection. This experiment demonstrates the compatibility of quantum control and inherent bit-flip protection at an unprecedented level, showing the viability of these dynamical qubits for future quantum technologies.

New opto-electro-mechanical sensor for two-dimensions dosimetry based on radiochromic films.

This work presents the validation of a new Opto‒Electro-Mechanical (MOEM) system consisting of a matrix of photodetectors for two-dimensional dosimetry evaluation with radiochromic films. The proposed system is based on a 5 × 10 matrix of photodetectors controlled by both in-house electronic circuit and graphical user interface, which enables optical measurements directly. We present the first tests performed in an X-ray machine and 137Cs source with that array by using Gafchromic EBT3 films. We obtained similar results than with a standard method (e.g. flat-bed scanner). Results were compared with Monte Carlo simulations and very good agreement was found. Results show the feasibility of using this system for dose evaluations. To the best of our knowledge, this is the first MOEM sensor for radiotherapy. Further developments are ongoing to create an advanced 16 × 16 LDRs system covering 1.6 cm × 1.6 cm with a 1 mm of spatial resolution. We point to develop a portable dosimetry tool delivering dose maps in real time to improve the clinical application of radiochromic films.

Perception of Protective Stabilization by Pediatric Dentists: A Qualitative Study.

INTRODUCTION: Pediatric dentists sometimes have to care for children who refuse to cooperate with the oral examination or dental treatment. Behavior management strategies are used, such as "tell-show-do," distraction, and positive reinforcement. Anxiety management can also be performed by the use of conscious sedation (oral premedication, nitrous oxide/oxygen inhalation). Unfortunately, these techniques are sometimes insufficient for providing oral care, and protective stabilization may be an option in some situations. Little is known on the impact of physical restraint and how practitioners feel about it. The objective of this study was to evaluate the perception of dentists using protective stabilization for dental care in children. METHODS: Semistructured qualitative interviews on the perception of pediatric dentists concerning protective stabilization were conducted in the pediatric dentistry department of the University Hospital of Toulouse, France. A thematic analysis of interview transcripts was provided via NVivo software. RESULTS: This analysis highlighted 3 main themes. First, the perceptions of dentists concerning protective stabilization showed that this procedure has a major psychological impact and led to a feeling of professional failure. Second, the reasons for which the child was stabilized were described; these concerned the child (behavior, age, number of treatments) and the environment (the parents and the medical team). Finally, we detailed how dentists manage the effects of using of protective stabilization. CONCLUSION: Dental surgeons must balance their requirement to make concrete decisions regarding the provision of care with their personal convictions about protective stabilization. This study also shows the need for specific training on this subject, as well as the desire of certain dentists that public authorities implement legislation on this matter. KNOWLEDGE TRANSFER STATEMENT: The findings of this study will improve the management of young patients by identifying situations where protective stabilization may be useful (age of the child, diagnosis, protection of the child or the medical team), while showing its psychological impact on practitioners. Finally, this work provides a basis for decision makers to propose a framework for the use of physical restraint.

Cadmium bioaccumulation and gastric bioaccessibility in cacao: A field study in areas impacted by oil activities in Ecuador.

Cacao from South America is especially used to produce premium quality chocolate. Although the European Food Safety Authority has not established a limit for cadmium (Cd) in chocolate raw material, recent studies demonstrate that Cd concentrations in cacao beans can reach levels higher than the legal limits for dark chocolate (0.8 mg kg-1, effective January 1st, 2019). Despite the fact that the presence of Cd in agricultural soils is related to contamination by fertilizers, other potential sources must be considered in Ecuador. This field study was conducted to investigate Cd content in soils and cacao cultivated on Ecuadorian farms in areas impacted by oil activities. Soils, cacao leaves, and pod husks were collected from 31 farms in the northern Amazon and Pacific coastal regions exposed to oil production and refining and compared to two control areas. Human gastric bioaccessibility was determined in raw cacao beans and cacao liquor samples in order to assess potential health risks involved. Our results show that topsoils (0-20 cm) have higher Cd concentrations than deeper layers, exceeding the Ecuadorian legislation limit in 39% of the sampling sites. Cacao leaves accumulate more Cd than pod husks or beans but, nevertheless, 50% of the sampled beans have Cd contents above 0.8 mg kg-1. Root-to-cacao transfer seems to be the main pathway of Cd uptake, which is not only regulated by physico-chemical soil properties but also agricultural practices. Additionally, natural Cd enrichment by volcanic inputs must not be neglected. Finally, Cd in cacao trees cannot be considered as a tracer of oil activities. Assuming that total Cd content and its bioaccessible fraction (up to 90%) in cacao beans and liquor is directly linked to those in chocolate, the health risk associated with Cd exposure varies from low to moderate.

A reinvestigation of the mechanism of Pseudomonas testosteroni delta 5-3-ketosteroid isomerase.

The mechanism of the isomerisation of delta 5-3,17-androstenedione by the isomerase (3-oxosteroid delta 4-delta 5-isomerase, EC 5.3.3.1) of Pseudomonas testosteroni has been reinvestigated with delta 5-[4-beta-2H]androstenedione as substrate in H2O and delta 5-androstenedione in 2H2O. A precise localisation of the label in delta 4-androstenendione has revealed that the previously reported 4 beta leads to 6 beta deuterium transfer accounts for only a part of the reaction. Along with this process, removal of the 4 alpha proton is also occurring. This has already been observed with mammalian isomerases. Hence the assumed difference in mechanism between the bacterial and mammalian enzymes is very unlikely.

Avidin binding of biotinylated analogues of substance P.

We report the bioactivities of three biotinylated analogues of Substance P, [alpha-biotinyl-Lys3]Substance P-(3-11), [alpha-biotinyl-Arg1]Substance P, [epsilon-biotinyl-Lys3]Substance P, as well as the bioactivities of their complexes with avidin on guinea pig ileum. The rate of dissociation of an [alpha-biotinyl-Arg1]Substance P-avidin complex has been determined in the presence of 2-(4'-hydroxyazobenzene) benzoic acid and [3H]biotin. The biphasic dissociation of a 4:4 complex between [alpha-biotinyl-Arg1]Substance P and avidin led us to postulate the existence of two sets of binding sites, with the following rates of dissociation, at 4 degrees C, kappa-1 = 6 x 10(-4) x s-1 and kappa-1 = 1.2 x 10(-5) x s-1. We have confirmed this non-equivalence of the four binding sites of avidin by nuclear magnetic resonance using a spin-echo technique. The [alpha-biotinyl-Arg1]Substance P-avidin may be used for the affinity chromatography of Substance P receptors and the decreased affinity of this complex may be taken as an advantage since it can be displaced under mild conditions, i.e. by biotin-containing buffer.

A reinvestigation of the mechanism of delta 5-3-ketosteroid isomerase from bovine adrenal glands.

The mechanism of the isomerization of androst-5-ene 3,17-dione by the isomerase of bovine adrenals has been reinvestigated using the methodology previously developed for the study of the bacterial enzyme of Pseudomonas testosteroni. However, owing to the lower activity of the mammalian enzyme, competitive non-enzymic reaction cannot be neglected. It has been shown that even in the absence of spontaneous isomerization, epimerization and exchange of the label on C4 takes place in the buffer. This prevents any quantitative discussion of the course of the reaction. It is however possible to conclude that the mechanism we have proposed for the bacterial enzyme that is, besides the classical 4 beta leads to 6 beta transfer and exchange with the medium, a competitive abstraction of the 4 alpha proton, accounts for the data obtained with the mammalian microsomes.

Cloning of the gp63 surface protease of Leishmania infantum. Differential post-translational modifications correlated with different infective forms.

The Leishmania cell surface virulence factor gp63 is a protease family that plays an important role in the survival of the parasite protozoon into the host macrophages. We have cloned and characterised the gp63 gene from L. infantum. The sequence analysis of the gene indicates the existence of a high degree of conservation with the other old world species L. major and L. donovani. The similarity is lower with new world species with the exception of L. chagasi which shows a strikingly high percentage of identity (99-100%). In L. infantum the gp63 gene expresses two polypeptides of 58 and 60 kDa, respectively, which show a similar proteolytic activity. The 60 kDa polypeptide is expressed during the whole life cycle of the promastigote form of the parasite with a moderate increase at the stationary phase of growth while the 58 kDa product, although slightly present in the logarithmic phase, notable increases its expression during the highly infectious stationary phase. RNA analysis showed that the presence in L. chagasi of these two polypeptides correlates with two RNA molecules and with the degree of parasite infectivity, whereas in the case of L. infantum a single 3 kb messenger RNA is detected through the whole promastigote life cycle. Our data indicate that in L. infantum, the differences in gene expression of the gp63 protease family according to parasite phase of growth seem to be due to a differential pattern of glycosilation of the polypeptides which correlates with the different infective forms of the promastigote form of the parasite.

Effect of reduced vitamin K esters on vitamin K-dependent carboxylation.

The hypothesis of a vitamin K hydroquinone hemicarbonate as intermediate of vitamin K-dependent carboxylation of glutamic residues, has been examined, by testing several vitamin K hydroquinone esters as inhibitors of the reaction. Among the esters that have been synthetized, a monoacetate proved to be an inhibitor. Kinetic analysis shows that the inhibition is no competitive with respect to vitamin K.

Photoaffinity labelling of the human mineralocorticoid receptor with steroids having a reactive group at position 3, 18 or 21.

The ability of a glucocorticoid (triamcinolone acetonide: TA) and three progesterone derivatives with photoreactive groups at different positions (promegestone: R5020; 18-oxo-18-vinylprogesterone: 18OVP; 21-diazoprogesterone: 21DP) to bind covalently to the human mineralocorticoid receptor (hMR) expressed in Sf9 insect cells was assessed. Sedimentation gradient analysis and exchange assays with aldosterone showed that [3H]TA, a partial mineralocorticoid agonist, and [3H]R5020, a pure antimineralocorticoid, were covalently bound to hMR after UV irradiation, with a labelling efficiency of approx. 3-5%. UV irradiation did not alter the heterooligomeric structure of the hMR, since the irradiated [3H]TA- and [3H]R5020-hMR complexes sedimented at approx. 9-10 S, as did the non-irradiated complexes. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed a band labelled by [3H]TA or [3H]R5020, having a molecular mass of 120 kDa. This band was not detected in the presence of an excess of the corresponding unlabelled steroid or when the cytosol was recovered from non-infected Sf9 cells. Electrophoresis of a truncated hMR (hMRDelta(1-351)) photolabelled with [3H]TA revealed a 80 kDa band, compatible with the molecular mass of the truncated hMR. Limited chymotrypsin proteolysis of the [3H]TA photolabelled hMR generated a 30 kDa fragment covalently associated with [3H]TA. As the 30 kDa fragment generated by chymotrypsin has been shown to encompass the entire ligand-binding domain of the hMR (B. Couette, J. Fagart, S. Jalaguier, M. Lombès, A. Souque, M.E. Rafestin-Oblin, Biochem. J. 315 (1996) 421-427), the present experiments provide evidence that [3H]TA is covalently bound to the ligand binding domain of the hMR. Exchange assays with [3H]A also revealed that unlabelled 18OVP and 21DP, two mineralocorticoid agonists bearing photoreactive groups at skeleton positions crucial for the ligand-MR interaction, are covalently bound to hMR with an approx. 30-35% labelling efficiency.

Enzymology of carbon-sulfur bond formation.

Mobilization of the sulfur of cysteine as persulfide is the first step of sulfur transfer into thiamin, molydopterin, 4-thiouridine, biotin and lipoic acid, but then the pathways diverge completely. For the first three compounds, one or several proteinic persulfides are involved, ending in the nucleophilic attack of a sulfur, persulfide, sulfide or thiocarboxylate on a carbonyl equivalent. Several proteins have been newly characterized, revealing homologies between the three biosynthetic routes and evolutionary relationships. In the case of biotin, and very probably of lipoic acid, the sulfur is transferred as sulfide into the [Fe-S] center of the enzyme. This [Fe-S] center is the ultimate sulfur donor, which quenches a carbon radical on the substrate. This radical is produced by homolytic cleavage of a C-H bond by a deoxyadenosyl radical arising from the reduction of S-adenosylmethionine.

Three years of antibiotic consumption evaluation in French nursing homes.

OBJECTIVES: We had for aim to assess antibiotic consumption and to better understand their use in nursing homes so as to target messages on relevant practice procedures sent to prescribers. DESIGN: The MedQual network asked nursing homes with in-house pharmacies to participate in a retrospective collection of yearly antibiotic consumption data with an Excel(®) spread sheet according to the Health Ministry recommendations. RESULTS: Fifty-two nursing homes participated in 2011, 2012, and 74 in 2013, accounting for 10% of the Pays de la Loire region's nursing homes and 15% of beds. The medians of total antibiotic consumption in daily-defined dose for 1000 patient-days were respectively 39 (32.4-49.0), 39.3 (34.4-52.9), and 44.8 (33.6-55.4). There was no significant difference between 2011 and 2013. Penicillins (J01C) were the most commonly used class with a median of 25.7 [IQ 18.8; 33.8] in 2011 and 30.4 [IQ 23.6; 41.3] in 2013. Quinolones (J01M) were the second most commonly used class with a median of 4.6 [IQ 2.9; 5.9] in 2011 and 3.8 [IQ 2.3; 6.5] in 2013, followed by the other beta-lactams (J01D) with a median of 2.5 [IQ 1.7; 4.5] in 2011 and 2,8 [IQ 1.7; 3.8] in 2013. CONCLUSION: The monitoring of antibiotic consumption in nursing homes in the Pays de la Loire Region since 2011 has allowed identifying inappropriate use and helped improve practices. No increase of overall consumption was observed in nursing homes but the distribution according to antibiotic class changed. The current objective is to extend this monitoring and to send personalized messages to prescribers.

The mineralocorticoid activity of progesterone derivatives depends on the nature of the C18 substituent.

To investigate the role of the C18 substituents in the agonist/antagonist properties of mineralocorticoids, the activities of certain C18-substituted progesterone (P) derivatives were examined. These compounds were characterized by an unsaturated side-chain in the case of 18-vinylprogesterone (18VP) and 18-ethynylprogesterone (18EP) and by an enone group in the case of 18-oxo-18-vinylprogesterone (18OVP). P and its 18-substituted derivatives bind to the recombinant human MR (hMR) overexpressed in Sf9 cells with the following hierarchy of affinity: P > aldosterone > 18VP > 18EP >> 18OVP. Functional cotransfection assays in CV-1 cells, using mouse mammary tumor virus promoter as a steroid receptor-inducible DNA target sequence, indicated that the mineralocorticoid activity depends on the nature of the C18 substituent. 18VP and 18EP retained the antimineralocorticoid feature of P, with the following order of activity: P = 18VP > 18EP. The antagonist potency of 18VP was higher (IC50, approximately 10(-8) M) than that of spironolactone (IC50, approximately 7 x 10(-8) M), the most widely used aldosterone antagonist. Interestingly, introducing an oxo function at C18 conferred agonist mineralocorticoid properties; 18OVP behaves as a full agonist (ED50, approximately 10(-7) M) with no antagonist activity. In contrast to what was observed when the three 18-substituted P derivatives acted through hMR, they retained the agonist feature of P through the human P receptor, with the following order of potency: P > 18VP = 18OVP > 18EP. The activity of the 18-substituted P derivatives through the human glucocorticoid receptor was only detected at concentrations higher than 10(-6) M; P and 18VP displayed a partial antagonist activity, whereas 18OVP had a full agonist activity (ED50, approximately 2 x 10(-6) M). Thus, the presence of an oxo group at C18(18OVP) does not change the agonist feature of P through human P receptor, but confers to the ligand an agonist activity through hMR, suggesting that the C18 carbonyl group of aldosterone plays a crucial role in its agonist activity.

The active site region of the vitamin K-dependent carboxylase includes both the amino-terminal hydrophobic and carboxy-terminal hydrophilic domains of the protein.

In order to localize the active site of the vitamin K-dependent carboxylase, we developed an affinity probe containing the propeptide and the first two carboxylatable glutamate residues conserved in many native substrates. This probe crosslinked to both the hydrophobic amino-terminal and hydrophilic carboxy-terminal domains of the carboxylase, in contrast with previous work which localized both the catalytic and the propeptide binding site within the amino-terminal hydrophobic domain. Amino acid analysis revealed that the mass of an amino-terminal fragment is seriously underestimated by SDS-PAGE. Reanalysis of the published data in light of this information suggests that a portion of the propeptide binding site resides within the carboxy-terminal hydrophilic domain.

Cloning, molecular analysis and differential cell localisation of the p36 RACK analogue antigen from the parasite protozoon Crithidia fasciculata.

The family of the RACK molecules (receptors for activated C kinases) are present in all the species studied so far. In the genus Leishmania, these molecules also induce a strong immune reaction against the infection. We have cloned and characterised the gene that encodes the RACK analogue from the parasite trypanosomatid Crithidia fasciculata (CACK). The molecule seems to be encoded by two genes. The sequence analysis of the cloned open reading frame indicates the existence of a high degree of conservation not only with other members of the Trypanosomatidae but also with mammalians. The study of the protein kinase C phosphorylation sites shows the presence of three of them, shared with the mammalian species, additional to those present in the other protozoa suggesting a certain phylogenetic distance between the protozoon Crithidia fasciculata and the rest of the Trypanosomatidae. The CACK-encoded polypeptide shows an additional sequence of four amino acids at the carboxy-terminal end, which produces a different folding of the fragment with the presence of an alpha-helix instead of the beta-sheet usual in all the other species studied. A similar result is elicited at the amino-terminal end by the change of three amino acid residues. The immunolocalisation experiments show that the CACK displays a pattern with a distribution mainly at the plasma membrane, different from that of the related Leishmania species used as control, that displays a distribution close to the nucleus. Altogether, the data suggest that the existence of the structural differences found may have functional consequences.

Biotin synthase mechanism: on the origin of sulphur.

Biotin synthase catalyses the last step of the biosynthesis of biotin in microorganisms and plants. The active protein isolated from Bacillus sphaericus and Escherichia coli contains an iron-sulphur (FeS) cluster. The native enzymes were depleted of their iron and inorganic sulphide and the resulting apoenzymes were chemically reconstituted with FeCl3 and Na2[34S] to give labelled (Fe34S) enzymes. These enzymes were functional and when assayed in vitro produced labelled biotin containing about 65% of 34S. These data strongly support the hypothesis that the sulphur of biotin is derived from the (FeS) centre of the enzyme.

Mössbauer studies of Escherichia coli biotin synthase: evidence for reversible interconversion between [2Fe-2S](2+) and [4Fe-4S](2+) clusters.

The nature and properties of the iron-sulphur (Fe-S) cluster in as-prepared and reduced biotin synthase of Escherichia coli have been investigated by Mössbauer spectroscopy. Our data clearly demonstrate that in the as-prepared sample, the cluster is present as [2Fe-2S](2+) with isomer shift, delta = 0.29 mm/s and quadrupole splitting, DeltaE(Q) = 0.53 mm/s, indicating incomplete cysteinyl-S coordination. Anaerobic reduction by dithionite in the presence of 55% (v/v) glycerol converts this form to [4Fe-4S](2+) (delta = 0.45 mm/s and DeltaE(Q) = 1.11 mm/s) and is accompanied by some destruction to Fe(2+). This cluster conversion is reversible and when exposed to air, the [4Fe-4S](2+) cluster is quantitatively reconverted to the [2Fe-2S](2+) cluster without any further cluster degradation.

Vitamin K dependent carboxylation: synthesis and biological properties of tetrazolyl analogues of pentapeptidic substrates.

The pentapeptides Phe-Leu-X-Glu-Val and Phe-Leu-X-X-Val, where X = 4-(5H-tetrazolyl)-2-aminobutyric acid (tetrazolyl analogue of glutamic acid), were synthesized by addition of tri-n-butyltin azide to the corresponding nitrile-containing peptides. These tetrazolyl peptides and a dinitrile precursor were tested as possible substrates and inhibitors of the vitamin K dependent carboxylation. Phe-Leu-X-Glu-Val was carboxylated (40% of the reference peptide Phe-Leu-Glu-Glu-Val, Km = 20 mM) exclusively on the glutamyl residue, whereas the dinitrile precursor and Phe-Leu-X-X-Val were not carboxylated. The latter was a competitive inhibitor with an affinity (Ki = 3 mM) close to that of the reference peptide (Km = 3 mM).