Site-directed mutagenesis was used to replace Lys68 of the human hypoxanthine phosphoribosyltransferase~HGPRTase! with alanine to exploit this less reactive form of the enzyme to gain additional insights into the structure activity relationship of HGPRTase. Although this substitution resulted in only a minimal~one-to threefold! increase in the K m values for binding pyrophosphate or phosphoribosylpyrophosphate, the catalytic efficiencies~k cat 0K m ! of the forward and reverse reactions were more severely reduced~6-to 30-fold!, and the mutant enzyme showed positive cooperativity in binding of a-d-5-phosphoribosyl-1-pyrophosphate~PRPP! and nucleotide. The K68A form of the human HGPRTase was cocrystallized with 7-hydroxy @4,3-d# pyrazolo pyrimidine~HPP! and Mg PRPP, and the refined structure reported. The PRPP molecule built into the @~F o Ϫ F c !f calc # electron density shows atomic interactions between the Mg PRPP and enzyme residues in the pyrophosphate binding domain as well as in a long flexible loop~residues Leu101 to Gly111! that closes over the active site. Loop closure reveals the functional roles for the conserved SY dipeptide of the loop as well as the molecular basis for one form of gouty arthritis~S103R!. In addition, the closed loop conformation provides structural information relevant to the mechanism of catalysis in human HGPRTase.
Background and objectives: In Andalusia there were no studies including a representative sample of children and adolescent population assessing growth and weight increase. Our objectives were to develop reference standards for weight, height and BMI for the Andalusian pediatric population, from 3 to 18 years of age for both genders, and to identify the final adult height in Andalusia.
Objective: To describe physical activity, sedentary behaviors and sleep duration in toddlers' participants of the WIC program in Puerto Rico and assess its association with excessive weight.Methods: This was a cross-sectional analysis of data gathered in the follow-up visit (12 months later) of a longitudinal study among toddlers 12-36 months old participants of the WIC program. In this follow-up visit, a Sleep, Sedentary Behaviors and Physical Activity Questionnaire was included.Results: From the 213 eligible participants for the follow-up visit, 76 completed the follow-up visit. Most were girls (52.6%), with median age 21 months and most were categorized as healthy weight (76.3%). In general, toddlers spent a total median of 142 min/d in sedentary behaviors, 300 min/d in physical activities and 690 min/d sleeping. There was a higher duration of physical activities among overweight/obese compared to healthy weights (p<0.05) but similar duration of sedentary behaviors and sleep by weight status (p>0.05). There was a greater proportion of overweight/obese toddlers meeting the screen time recommendation (88.9%) compared to healthy weight toddlers (62.1%; p<0.05). Also, there was a significant positive age-adjusted correlation between time spent in unstructured physical activity (R=0.23, p<0.05) with weightfor-length z-score. Infant weight status was not significantly correlated to parent's perception or knowledge of physical activity or sleep in toddlers (p>0.05).
Conclusion:Most toddlers studied met the recommendations for duration of sleep, sedentary behaviors, and physical activity. Overweight/obese toddlers engage in more physical activities than those with a healthy weight status. These findings could be due to educational interventions by the WIC program to promote physical activities, as these toddlers are active WIC participants.
El ámbito objetivo de aplicación de la ley de contratos del sector público SUMARIO: I. El nuEvo EnfoquE dE lA lEgIslAcIón dE contrAtos. II. lA tIpologíA dE EntIdAdEs y contrAtos En lA lEy dE con-trAtos dEl sEctor públIco. lA nuEvA cAtEgorIzAcIón dE los contrAtos AdMInIstrAtIvos y prIvAdos En funcIón dE lA EntIdAd contrAtAntE. III. los contrAtos suJEtos A rEgu-lAcIón ArMonIzAdA y los contrAtos AsIMIlAdos. El concEpto dE podEr AdJudIcAdor. Iv. nEgocIos y rElAcIonEs JurídI-cAs ExcluIdAs. dElIMItAcIón gEnErAl y AplIcAcIón dE los prIncIpIos gEnErAlEs dE lA lcsp. v. los convEnIos dE colAbo-rAcIón cElEbrAdos EntrE lAs AdMInIstrAcIonEs y lAs EntI-dAdEs públIcAs y su ExclusIón dE lA lcsp. vI. los contrAtos "In housE provIdIng". vII. lA ExclusIón dE los contrAtos En El sEctor dE lA dEfEnsA. lA fAltA dE AplIcAcIón dE los prIncIpIos dE concurrEncIA y trAnspArEncIA En El áMbIto dE los contrAtos públIcos dE dEfEnsA. lA nEcEsIdAd dE gA-rAntIzAr El rEspEto dE los prIncIpIos dE lA contrAtAcIón públIcA con AlgunAs EspEcIAlIdAdEs. vIII. los contrAtos dE sErvIcIos y suMInIstro pArA lA EJEcucIón dE proyEctos dE InvEstIgAcIón.
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