Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu.

Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu's surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-meter-long elliptical crater. This exposed material is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500 to 700 kilograms per cubic meter, which is about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 grams of material, which will be delivered to Earth in 2023.

Immediate reinforcement increased duration of time riding the stationary bicycle in children with autism spectrum disorder: a pilot study.

The necessity of promoting physical activity in individuals with Autism Spectrum Disorder (ASD) has been emphasized for decades. One of the barriers to participate in physical activity for individuals with ASD is limited interest and motivation. Therefore, understanding the motivation to exercise in this population is important. The objective was to determine the effect of using contingent reinforcement in the form of watching a preferred DVD to increase duration of time pedalling on a stationary bicycle within their predetermined target heart rate zone (THRZ) in children with ASD. Using a crossover design, seven participants (11 2.7 years) who were diagnosed with ASD were randomly assigned to either Group A or B. Time spent pedalling on a bicycle within the THRZ was analysed using a linear mixed-effect model with Bonferroni adjustments. The results showed that the DVD intervention motivated children with ASD to exercise for more than 10 minutes in moderate to vigorous physical activity compared to when they were exercising without watching a DVD. This result is significant as number of studies have revealed that 10 minutes of exercise could bring improvements in activities of daily living such as behaviors and academic performance in school.

Associations of adolescent lifestyle behaviors with body mass index within a nationally representative sample of US adolescents: a quantile regression analysis.

OBJECTIVES: The purpose of this study was to examine the associations between lifestyle behavior variables such as physical activity, television watching, computer use, and school night sleep duration with body mass index percentile (BMI%) using quantile regression within a representative sample of adolescents who completed the 2017 US National Youth Risk Behavior Survey. STUDY DESIGN: The study design was a cross-sectional study. METHODS: A multistage cluster sampling procedure obtained a representative sample of US adolescents. The number of sampled adolescents submitting questionnaires with BMI% data was 13,146. To examine the associations between lifestyle behaviors and BMI%, simultaneous quantile regression was used. RESULTS: When relationships were modeled at every 10th percentile, more precise parameter estimates were observed at higher percentiles. Across the interquartile range, physical activity associated with lower BMI% at the 50th and 75th percentiles (brange = -2.27% to -5.24%, P < 0.05), television watching associated with higher BMI% at the 25th to 75th percentiles (brange = 2.29%-4.16%, P < 0.05), sleep durations less than 8 h per school night associated with higher BMI% at the 25th and 50th percentile (brange = 2.81%-8.26%, P < 0.05), and 10 or more hours of school night sleep associated with higher BMI% at the 50th and 75th percentile (brange = 3.43%-7.53%, P < 0.05). CONCLUSIONS: Higher levels of physical activity associated with lower BMI% and longer time watching television, school night sleep durations less than 8 h, and school night sleep durations of 10 h or more at higher quantiles associated with higher BMI% in adolescents. Estimates of association were more precise within higher quantiles.

Biosynthesis of all-trans-retinoic acid from retinal. Recognition of retinal bound to cellular retinol binding protein (type I) as substrate by a purified cytosolic dehydrogenase.

An NAD-dependent rat liver cytosolic dehydrogenase accepted as substrate retinal generated in situ by microsomes from retinol bound to excess CRBP (cellular retinol binding protein, type I). This activity, which was not retained by anion-exchange chromatography at pH 9.15, was designated P1. P1 activity increased 2.5-fold, with no statistically significant change in its K or Hill coefficient, in liver cytosol from rats fed a retinoid-deficient diet. Orally dosed retinoic acid partially suppressed the increase. Activities chromatographically similar to hepatic P1 were observed in cytosols from rat kidney and testes. P1, purified from rat liver cytosol, had a pI of approximately 8.3, migrated as a tetramer (214 kDa) on a Sephadex G-200 column, and had a subunit molecular mass of 55 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. With free retinal it catalyzed a maximum rate of retinoic acid synthesis of 265 nmol/min/mg of protein and exhibited allosteric kinetics with a K of 0.76 +/- 0.35 microM and a Hill coefficient of 1.5 +/- 0.13 (mean +/- S.D., n = 4). Substrate inhibition was noted with retinal concentrations greater than 6 microM. The purified enzyme not only recognized retinal generated by microsomes as substrate, but also recognized retinal bound to CRBP. The rates of retinoic acid synthesis from CRBP-retinal, with a series of increasing apoCRBP concentrations, exceeded the rates that would be supported by the free retinal present. The CRBP-retinal complex exhibited allosteric kinetics (K, 0.13 microM; Hill coefficient, 1.75; averages of duplicates) in the presence of excess apoCRBP (the ratio total CRBP/total retinal at each concentration of retinal was 2). This enzyme is likely to play a significant role in retinoic acid synthesis in vivo, because it participates in the synthesis of retinoic acid from a physiologically occurring form of retinol (holoCRBP), reflects retinoid status, and is distributed in extrahepatic tissues in addition to liver. These results also suggest a novel role for CRBP in retinoid metabolism, facilitating the conversion of retinal into retinoic acid.

Microsomal retinal synthesis: retinol vs. holo-CRBP as substrate and evaluation of NADP, NAD and NADPH as cofactors.

Holo-CRBP (cellular retinol binding protein) is recognized specifically by an NADP-dependent microsomal retinol dehydrogenase and protects retinol from conversion into retinal by NAD and NADPH dependent dehydrogenases. The synthesis of retinal from free retinol is catalyzed by both NADP- and NAD-dependent pathways, with the former being the preferred one (Km of 4 vs. 22 microM for retinol, and Vmax/Km of 33 vs. 9, respectively). NADPH does not support quantitatively significant retinal synthesis from physiological concentrations of retinol or holo-CRBP, if an NADPH regenerating system is used to prevent NADP formation.

Holocellular retinol binding protein as a substrate for microsomal retinal synthesis.

Holocellular retinol binding protein (holo-CRBP) was substrate for retinal synthesis at physiological pH with microsomes prepared from rat liver, kidney, lung, and testes. Four observations indicated that retinal synthesis was supported by holo-CRBP directly, rather than by the unbound retinol in equilibrium with CRBP. First, the rate of retinal synthesis with holo-CRBP exceeded the rate that was observed from the concentration of unbound retinol in equilibrium with CRBP. Second, NADP was the preferred cofactor only with holo-CRBP, supporting a rate about 3-fold greater than that of NAD. In contrast, with unbound retinol as substrate, similar rates of retinal formation were supported by either NAD or NADP. Third, the rate of retinal synthesis was not related to the decrease in the concentration of unbound retinol in equilibrium with holo-CRBP caused by increasing the concentration of apo-CRBP. Fourth, the rate of retinal synthesis increased with increases in the concentration of holo-CRBP as a fixed concentration of unbound retinol was maintained. This was achieved by increasing both apo-CRBP and holo-CRBP, but keeping constant the ratio apo-CRBP/holo-CRBP. Retinal formation from holo-CRBP displayed typical Michaelis-Menten kinetics with a Km about 1.6 microM, less than the physiological retinal concentration of 4-10 microM in the livers of rats fed diets with recommended vitamin A levels. The Vmax for retinal formation from holo-CRBP was 14-17 pmol min-1 (mg of protein)-1, a rate sufficiently high to generate adequate retinal to contribute significantly to retinoic acid synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)