An active x-ray beamstop based on single crystal CVD diamond at beamline SWING.

A compact active x-ray beamstop has been developed for the SWING beamline at Synchrotron SOLEIL with two main functions, blocking the x-ray beam directly transmitted by the sample to protect the Dectris EigerX4M 2D detector and monitoring its intensity. The beamstop is composed of a sensor inserted in a well of tungsten carbide. The sensor is based on a piece of free-standing single crystal chemical vapor deposited diamond used in the ionization chamber mode. The beamstop has been installed on the beamline detector stage within the detection vacuum chamber, just upstream of the large 2D detector. The intensity monitoring performance (rms noise over signal) is shown to be better than 0.06% and the linearity is shown to be better than 2% for over more than five decades. The beamstop has been calibrated between 5 and 16 keV to provide the photon flux measurements in absolute units (ph/s). The specific design of the beamstop increases the small-angle x-ray scattering q-range by a factor of 1.5 in the low angle side, as compared to the previous active beamstop, based on a more standard commercial Si diode. The beamstop has been available for three years for SWING user operation (5-17 keV). It is fully compatible with the different beamline operating modes and fluxes, except in the microbeam mode, where the very divergent beam becomes too large at the beamstop position, and the previous, larger, beamstop is then more appropriate.

COMET: a new end-station at SOLEIL for coherent magnetic scattering in transmission.

A new instrument named COMET for COherent Magnetic scattering Experiments in Transmission using polarized soft X-rays has been designed and built. This high-vacuum setup is placed at the intermediate focal point of the elastic branch of the SEXTANTS beamline at Synchrotron SOLEIL. The main application is in solid state physics, the instrument being optimized for studying material properties using coherent scattering of soft X-rays with an emphasis on imaging, with chemical selectivity, the magnetic domains of artificially nano-structured materials. The instrument's principal features are presented and illustrated through recently performed experiments.

Tomography and imaging at the PSICHE beam line of the SOLEIL synchrotron.

PSICHE (Pressure, Structure and Imaging by Contrast at High Energy) is the high-energy beam line of the SOLEIL synchrotron. The beam line is designed to study samples at extreme pressures, using diffraction, and to perform imaging and tomography for materials science and other diverse applications. This paper presents the tomograph and the use of the beam line for imaging, with emphasis on developments made with respect to existing instruments. Of particular note are the high load capacity rotation stage with free central aperture for installing large or complex samples and sample environments, x-ray mirror and filter optics for pink beam imaging, and multiple options for combining imaging and diffraction measurement. We describe how x-ray imaging techniques have been integrated into high-pressure experiments. The design and the specifications of the beam line are described, and several case studies drawn from the first user experiments are presented.

In adult patients with type 1 diabetes healthy lifestyle associates with a better cardiometabolic profile.

BACKGROUND/AIMS: Little is known about lifestyle habits of adults with type 1 diabetes (T1D) and their association with cardiometabolic risk (CMR) factors. The aims of the present study were to determine the prevalence of adults with T1D who adopted a healthy lifestyle and to explore the association between a healthy lifestyle and the cardiometabolic profile. METHODS AND RESULTS: This is a cross-sectional analysis of 115 adults with T1D. Participants wore a motion sensor and completed a 3-day food record. The following CMR factors were assessed: body mass index, waist circumference, body composition (iDXA), glycated hemoglobin, lipids and blood pressure. Insulin resistance was estimated (estimated glucose disposal rate). Participants were classified according to the number of healthy lifestyle habits adopted (ranging from 0 to 3): regular physical activity (physical activity level ≥1.7), good diet quality (Canadian Healthy Eating Index score >80) and none-smoking status. The proportion of participants who adopted 3, 2, 1 or 0 lifestyle habits were 11%, 30%, 37%, and 23%, respectively. As the number of healthy lifestyle habits adopted increased, participants had significantly lower body mass index, waist circumference, body fat, total cholesterol, non-HDL-cholesterol, triglycerides and systolic blood pressure (p < 0.05). In addition, a trend for lower estimated insulin resistance was observed (p = 0.06). For each increase of one healthy lifestyle habit, body mass index decreased by 1.9 kg/m(2), waist circumference by 4.0 cm for men and 4.8 cm for women and trunk fat by 3.6% for men and 4.1% for women. CONCLUSIONS: These results suggest the importance of a healthy lifestyle among adults with T1D in order to control CMR factors.

Are bedtime nutritional strategies effective in preventing nocturnal hypoglycaemia in patients with type 1 diabetes?

Hypoglycaemia remains the major limiting factor for adequate diabetes control for patients with type 1 diabetes (T1D), especially during the night-time. Although nutritional strategies for nocturnal hypoglycaemia (NH) prevention are regularly suggested in clinical practice, there is no evidence-based recommendation for the usefulness and optimal composition of a bedtime snack. The aim of this narrative review was to analyse the current state of knowledge on nutritional strategies to prevent NH in individuals with T1D. A literature search was conducted, using PubMed and Medline (1946 to 2013); 16 studies were retrieved. Overall, the level of evidence was low. Results indicated that a calibrated bedtime snack based on bedtime blood glucose (BG) level could be effective to reduce NH occurrence for patients treated with human or animal insulin (short-acting combined with lente, ultralente and/or intermediate-acting insulin), but there is no evidence for patients treated with insulin analogues as part of multiple daily injections or insulin pump regimen. Some evidence suggests that including uncooked cornstarch or alanine in the bedtime snack composition could provide some benefits for the prevention of NH. Individualized recommendations of a bedtime snack intake for patients or situations at high risk for NH (long standing diabetes, hypoglycaemia unawareness, prior physical activity, alcohol consumption, bedtime BG close to hypoglycaemia threshold) appear as a prudent recommendation. On the basis of the available evidence, a bedtime snack cannot be recommended systematically but it might be useful if prescribed in an individualized fashion; further research is needed to evaluate these strategies.

Carbohydrate counting accuracy and blood glucose variability in adults with type 1 diabetes.

AIMS: Carbohydrate counting is an established approach used by patients with type 1 diabetes to improve their glycemic control. The aims of this study were to evaluate, in real life conditions, the accuracy of meal carbohydrate estimate and its impact on glycemic variability. METHODS: In this cross-sectional study, we observed the ability of 50 adults (48% women) with type 1 diabetes (age: 42.7±11.1 years); diabetes duration: 21.4±12.7 years; HbA1c: 7.2±1.2% (60±10 mmol/mol) to accurately estimate carbohydrates by analyzing 72-h food records and their corresponding 72-h blood glucose excursions using a continuous glucose monitor. RESULTS: The mean meal carbohydrate difference, between the patients' estimates and those assessed by a dietitian using a computerized analysis program, was 15.4±7.8 g or 20.9±9.7% of the total CHO content per meal (72.4±34.7 g per meal). Sixty-three percent of the 448 meals analyzed were underestimated. Greater differences in CHO's estimates predicted higher glycemic variability, as measured by the MAGE index and glucose standard deviation, and decreased time with glucose values between 4 and 10 mmol/L (R²=0.110, 0.114 and 0.110, respectively; P<0.05). CONCLUSION: Inaccurate carbohydrate counting is frequent and associated with higher daily blood glucose variability in adults with type 1 diabetes.

The Barriers to Physical Activity in Type 1 Diabetes (BAPAD-1) scale: predictive validity and reliability.

AIM: Perceived barriers are one determinant of physical activity. Depending on the study population, these barriers can vary. The aim of this study was to assess the reliability and predictive validity of the 'Barriers to Physical Activity in Type 1 Diabetes' (BAPAD-1) scale, developed by Dubé et al. METHODS: A total of 77 adults (48% women; age: 43.5±10.4; body mass index: 25.2±4.3kg/m(2); HbA(1c): 7.6±1.3%) with type 1 diabetes completed the questionnaire and an evaluation of their physical activity using an accelerometer (8.4±1.2 days) and cardiorespiratory fitness assessment (VO(2)(peak)). To evaluate the temporal stability of the questionnaire, a subgroup of 17 participants answered the BAPAD-1 scale on both visits required by the protocol (10±4 days). RESULTS: The BAPAD-1 scale showed good internal validity with an inter-items correlation coefficient (Cronbach's correlation) of 0.85. The intraclass correlation coefficient for the two times the scales were completed was 0.80. The BAPAD-1 score was negatively correlated with both physical activity energy expenditure (r=-0.25; P=0.03) and VO(2)(peak) adjusted for gender and age (r=-0.27; P=0.02). CONCLUSION: The BAPAD-1 scale is a reliable and valid tool for assessing salient barriers to physical activity. In future, this scale could be used to describe the factors accounting for physical activity, and for planning interventions aimed at promoting physical activity among adults with type 1 diabetes.

Phosphate groups modifying myelin basic proteins are metabolically labile; methyl groups are stable.

Young and adult rats received intracranial injections of [33P]orthophosphoric acid. The time course of the appearance and decay of the radioactive label on basic proteins in isolated myelin was followed for 1 mo. Incorporation was maximal by 1 h, followed by a decay phase with a half-life of approximately 2 wk. However, radioactivity in the acid-soluble precursor pool (which always constituted at least half of the total radioactivity) decayed with a similar half-life, suggesting that the true turnover time of basic protein phosphates might be masked by continued exchange with a long-lived radioactive precursor pool. Calculations based on the rate of incorporation were made to more closely determine the true turnover time; it was found that most of the phosphate groups of basic protein turned over in a matter of minutes. Incorporation was independent of the rate of myelin synthesis but was proportional to the amount of myelin present. Experiments in which myelin was subfractionated to yield fractions differing in degree of compaction suggested that even the basic protein phosphate groups of primarily compacted myelin participated in this rapid exchange. Similar studies were carried out on the metabolism of radioactive amino acids incorporated into the peptide backbone of myelin basic proteins. The metabolism of the methyl groups of methylarginines also was monitored using [methyl-3H]methionine as a precursor. In contrast to the basic protein phosphate groups, both the peptide backbone and the modifying methyl groups had a metabolic half-life of months, which cannot be accounted for by reutilization from a pool of soluble precursor. The demonstration that the phosphate groups of myelin basic protein turn over rapidly suggests that, in contrast to the static morphological picture, basic proteins may be readily accessible to cytoplasm in vivo.