Differential regulation of protein synthesis in skeletal muscle and liver of neonatal pigs by leucine through an mTORC1-dependent pathway

Neonatal growth is characterized by a high protein synthesis rate that is largely due to an enhanced sensitivity to the postprandial rise in insulin and amino acids, especially leucine. The mechanism of leucine＇s action in vivo is not well understood. In this study, we investigated the effect of leucine infusion on protein synthesis in skeletal muscle and liver of neonatal pigs. To evaluate the mode of action of leucine, we used rapamycin, an inhibitor of mammalian target of rapamycin （mTOR） complex-1 （mTORC1）. Overnight-fasted 7-day-old piglets were treated with rapamycin for 1 hour and then infused with leucine （400 μmol·kg^-1·h^-1） for 1 hour. Leucine infusion increased the rate of protein synthesis, and ribosomal protein S6 kinase 1 （S6K1） and eukaryotic initiation factor （elF） 4E-binding protein-1 （4E-BP1） phosphorylation in gastrocnemius and masseter muscles （P 〈 0.05）, but not in the liver. The leucine-induced stimulation of protein synthesis and S6K1 and 4E-BP1 phosphorylation were completely blocked by rapamycin, suggesting that leucine action is by an mTORC1-dependent mechanism. Neither leucine nor rapamycin had any effect on the activation of the upstream mTQRC1 regulators, AMP-activated protein kinase and protein kinase B, in skeletal muscle or liver. The activation of elF2α and elongation factor 2 was not affected by leucine or rapamycin, indicating that these two pathways are not limiting steps of leucine-induced protein synthesis. These results suggest that leucine stimulates muscle protein synthesis in neonatal pigs by inducing the activation of mTORC1 and its downstream pathway leading to mRNA translation.

Validation of the Physical Activity Questionnaire for Older Children(PAQ-C) among Chinese Children

Objective This study initially validates the Chinese version of the Physical Activity Questionnaire for Older Children （PAQ-C）, which has been identified as a potentially valid instrument to assess moderate-to-vigorous physical activity （MVPA） in children among diverse racial groups. Methods The psychometric properties of the PAQ-C with 742 Hong Kong Chinese children were assessed with the scale＇s internal consistency, reliability, test-retest reliability, confirmatory factory analysis （CFA） in the overall sample, and multistep invariance tests across gender groups as well as convergent validity with body mass index （BMI）, and an accelerometry-based MVPA. Results The Cronbach alpha coefficient （α=0.79）, composite reliability value （p=0.81）, and the intraclass correlation coefficient （α=0.82） indicate the satisfactory reliability of the PAQ-C score. The CFA indicated data fit a single factor model, suggesting that the PAQ-C measures only one construct, on MVPA over the previous 7 days. The multiple-group CFAs suggested that the factor Ioadings and variances and covariances of the PAQ-C measurement model were invariant across gender groups. The PAQ-C score was related to accelerometry-based MVPA （r=0.33） and inversely related to BMI （r=0.18）. Conclusion This study demonstrates the reliability and validity of the PAQ-C in Chinese children.

Regulation of protein degradation pathways by amino acids and insulin in skeletal muscle of neonatal pigs

Background： The rapid gain in lean mass in neonates requires greater rates of protein synthesis than degradation. We previously delineated the molecular mechanisms by which insulin and amino acids, especially leucine, modulate skeletal muscle protein synthesis and how this changes with development. In the current study, we identified mechanisms involved in protein degradation regulation. In experiment 1,6- and 26-d-old pigs were studied during 1） euinsulinemic-euglycemic-euaminoacidemic, 2） euinsulinemic-euglycemiohyperaminoacidemic, and 3） hyperinsulinemic-euglycemic-euaminoacidemic clamps for 2 h. In experiment 2, 5-d-old pigs were studied during 1） euinsulinemic-euglycemic-euaminoacidemic-euleucinemic, 2） euinsulinemic-euglycemic-hypoaminoacidemic- hyperleucinemic, and 3） euinsulinemic-euglycemic-euaminoacidemic-hyperleucinemic clamps for 24 h. We determined in muscle indices of ubiquitin-proteasome, i.e., atrogin-1 （MAFbx） and muscle RING-finger protein-1 （MuRF1） and autophagy-lysosome systems, i.e., unc51-1ike kinase 1 （UKL1）, microtubule-associated protein light chain 3 （LC3）, and lysosomal-associated membrane protein 2 （Lamp-2）. For comparison, we measured ribosomal protein 56 （rpS6） and eukaryotic initiation factor 4E （elF4E） activation, components of translation initiation. Results： Abundance of atrogin-1, but not MuRF1, was greater in 26- than 6-d-old pigs and was not affected by insulin, amino acids, or leucine. Abundance of ULK1 and LC3 was higher in younger pigs and not affected by treatment. The LC3-11/LC3-1 ratio was reduced and ULK1 phosphorylation increased by insulin, amino acids, and leucine. These responses were more profound in younger pigs. Abundance of Lamp-2 was not affected by treatment or development. Abundance of elF4E, but not rpS6, was higher in 6- than 26-d-old-pigs but unaffected by treatment. Phosphorylation of elF4E was not affected by treatment, however, insulin, amino acids, and leucine stimulated rpS6 phosphorylation, and the responses decreased with development.

人生的第二智慧——杨凤先生对科学的不懈探索

我国动物营养学发展到今天,凝聚了无数前辈、专家的智慧。他们对科学的不懈探索让人感动。在他们身上,沉淀的不仅仅是科学知识宝藏,更加闪烁着人生的感悟与哲学。他们不仅为动物营养事业做出了卓越贡献,更重要的是,言传身教感染着身边每一位满怀激情的学子。也正因为此,我们的事业才得以永续发展。杨凤先生即是如此。作为动物营养界泰斗,先生不仅在动物营养研究领域,尤其是在利用能量动态平衡和代谢组学来重新确定营养需要量的研究中贡献卓越,而且为人师表,启迪智慧,培养了大量的人才。在先生90寿辰来临之前,先生的学生,曾获"海外华人杰出青年科学家"荣誉的关新富教授,特撰此文,表达谢意。编辑部借此机会,向杨凤先生以及其他各位曾经对我国饲料及畜牧业做出突出贡献的前辈们表达敬意!

Conjugated Linoleic Acid and Dietary Fats Differentially Affect Hepatic ACAT Activity and LDL-Cholesterol in Postweanling Pigs Fed Low-Fat Diets

ABSTRACT：Two separate studies tested the hypoth- esis that plasma low-density lipoprotein cholesterol LDL-C ） can be decreased by conjugated linoleic acid （CLA） by depressing hepatic acyl-coenzyme A： cholesterol acyltransferase （ACAT） activity. In the first experiment, 3 groups of 6 early-weaned piglets were fed low-fat diets containing either 1.5% CLA, 1.5% corn oil or 1.5% beef tallow;fat provided 8% of the energy intake. In the second experiment, 4 groups of 6 early-weaned piglets were fed high-fat di- ets containing either 15% beef tallow, 12% beef tal- low plus 3% CLA, 15% corn oil, or 12% corn oil plus 3% CLA; fat provided 29% of energy intake. Cholesterol was balanced across diets in both experi-ments. In pigs fed the low-fat diets, all dietary fats in- creased LDL-C and triacylglycerols and decreased high-density lipoprotein cholesterol （ HDL-C ） and very low-density lipoprotein cholesterol （VLDL-C）. LDL-C was the same in pigs fed low-fat tallow or low-fat CLA diets. However, ACAT activity was near- ly 80% higher in pigs fed the low-fat tallow diet than in pigs fed the low-fat CLA diets. All high-fat diets increased LDL-C, HDL-C and triacylglycerols equally with no effect on VLDL-C. There were no unique fat- ty acid effects of the high-fat diets on ACAT activity. We conclude that supplemental fats had differential effects on hepatic ACAT activity and LDL-C, but on- ly in pigs fed low-fat diets.

补充抗氧化剂对马拉维儿童恶性营养不良症的预防作用:随机双盲安慰剂对照试验

Objective: To evaluate the efficacy of antioxidant supplementation in preventi ng kwashiorkor in a population of Malawian children at high risk of developing k washiorkor. Design: Prospective, double blind, placebo controlled trial randomis ed by household. Setting: 8 villages in rural southern Malawi. Participants: 237 2 children in 2156 households aged 1-4 years were enrolled; 2332 completed the trial. Intervention: Daily supplementation with an antioxidant powder containing riboflavin, vitamin E, selenium, and N-acetylcysteine in a dose that provided about three times the recommended dietary allowance of each nutrient or placebo for 20 weeks. Main outcome measures: The primary outcome was the incidence of oe dema. Secondary outcomes were the rates of change for weight and length and the number of days of infectious symptoms. Results: 62 children developed kwashiorko r (defined by the presence of oedema); 39/1184 (3.3%)-were in the antioxidant group and 23/1188 (1.9%) were in the placebo group (relative risk 1.70, 95%con fidence interval 0.98 to 2.42). The two groups did not differ in rates of weight or height gain. Children who received antioxidant supplementation did not exper ience less fever, cough, or diarrhoea. Conclusions: Antioxidant supplementation at the dose provided did not prevent the onset of kwashiorkor. This finding does not support the hypothesis that depletion of vitamin E, selenium, cysteine, or riboflavin has a role in the development of kwashiorkor.

西班牙儿童代谢综合征的遗传学定量分析

Childhood obesity is associated with a constellation of metabolic derangements including glucose intolerance, hypertension, and dyslipidemia, referred to as metabolic syndrome. The purpose of this study was to investigate genetic and environmental factors contributing to the metabolic syndrome in Hispanic children. Metabolic syndrome, defined as having three or more metabolic risk components, was determined in 1030 Hispanic children, ages 4- 19 y, from 319 families enrolled in the VIVA LA FAMILIA study. Anthropometry, body composition by dual energy x- ray absorptiometry, clinical signs, and serum biochemistries were measured using standard techniques. Risk factor analysis and quantitative genetic analysis were performed. Of the overweight children, 20% , or 28% if abnormal liver function is included in the definition, presented with the metabolic syndrome. Odds ratios for the metabolic syndrome were significantly increased by body mass index z score and fasting serum insulin; independent effects of sex, age, puberty, and body composition were not seen. Heritabilities ± SE for waist circumference, triglycerides (TG), HDL, systolic blood pressure (SBP), glucose, and alanine aminotransferase (ALT) were highly significant. Pleiotropy (a common set of genes affecting two traits) detected between SBP and waist circumference, SBP and glucose, HDL and waist circumference, ALT and waist circumference, and TG and ALT may underlie the clustering of the components of the metabolic syndrome. Significant heritabilities and pleiotropy seen for the components of the metabolic syndrome indicate a strong genetic contribution to the metabolic syndrome in overweight Hispanic children.

The Plant Vascular System: Evolution, Development and Functions

The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essentialfunctions performed by the vascular system, namely the delivery of resources （water, essential mineral nutrients, sugars and amino acids） to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.

Plant calcium oxalate crystal formation, function, and its impact on human health

Crystals of calcium oxalate have been observed among members from most taxonomic groups of photosynthetic organisms ranging from the smallest algae to the largest trees. The biological roles for calcium oxalate crystal formation in plant growth and development include high-capacity calcium regulation, protection against herbivory, and tolerance to heavy metals. Using a variety of experimental approaches researchers have begun to unravel the complex mechanisms controlling formation of this biomineral. Given the important roles for calcium oxalate formation in plant survival and the antinutrient and pathological impact on human health through its presence in plant foods, researchers are avidly seeking a more comprehensive understanding of how these crystals form. Such an understanding will be useful in efforts to design strategies aimed at improving the nutritional quality and production of plant foods.

儿童功能性胃肠病罗马Ⅳ标准

罗马标准是目前关于功能性胃肠病（ FGID）分类最全面且不断更新的标准。罗马Ⅰ、Ⅱ标准分别于1994年、1999年发布。罗马Ⅱ标准开始单列儿童FGID分类。2006年，根据年龄不同，婴幼儿（0-36个月）和儿童（〉36个月） FGID的罗马Ⅲ诊断标准发布，但相关的流行病学、病理生理学、诊断检查、治疗策略以及预后等资料都很少。

Hyperactivity of a midbrain dopamine to 5-HT circuit causes anorexia

Anorexia nervosa(AN)is a severe eating disorder that can eventually lead to death,buteffective the rapiesare missing dueto a lack of knowledge about its pathophysiology.Dopamine(DA)neurons in theventral tegmental area(VTA)and serotonin(5-HT)neurons in the dorsal Raphe nucleus(DRN)play essential roles in the control of eating and have been reported to be as sociated with human AN(Zhou and Palmiter,1995;Xu et al.,2017;Watson et al.,2019;He et al.,2021).