Role of nutrients in the regulation of in vivo protein metabolism in humans

Nutrients regulate protein metabolism both in an acute fashion and on a long-term basis. The ingestion of meals is associated with a dramatic switch from an overall catabolic state to a state of net protein anabolism. The acute response of protein metabolism to meal ingestion is mediated, in part, by an increase in insulin secretion, itself a consequence of glucose absorption. Whereas insulin may primarily suppress rates of proteolysis, amino acids are responsible for the stimulation of protein synthesis that follows food intake. In the long run, the effects of nutrition on protein metabolism depend on the energy supply, the source of the energy (carbohydrate versus fat) and dietary protein intake. Finally, specific amino acids, such as glutamine, may play an additional role as protein anabolic agents.     

早期营养对肝脏脂代谢程序化影响的研究进展

生命早期营养状况与成年期肥胖及代谢综合征的发生密切相关.脂代谢异常是影响成年期疾病发生的重要机制.肝脏是脂代谢的主要场所,进行脂肪酸的摄入、合成、酯化、氧化及输出.生命早期不良营养环境使肝脏及其组织结构的发育、细胞数目和代谢功能产生适应性的改变,持续影响后期肝脏脂代谢的各个途径,研究并阐明早期营养对肝脏脂代谢功能的程序化影响及其相关的分子调控机制,可为成年期疾病的早期防治提供理论依据及潜在的分子靶标.     

肥胖男童骨密度变化与骨代谢指标及胰岛素抵抗的关系探讨

目的 探讨单纯性肥胖男童骨密度变化与骨代谢生化指标及胰岛素抵抗之间的关系,以了解肥胖男童骨代谢异常可能的发病机制.方法 应用定量骨密度超声仪测定70例7～14岁小同体质指数(BMI≥23)的肥胖男童及20例年龄、性别匹配的健康男童的桡骨远端的超声传播速度(SOS),对其骨骼矿物质密度(BMD)进行评价.并对其空腹血钙(Ca)、磷(P)、碱性磷酸酶(ALP)、血糖(FBG)、胰岛素(FINS)、骨钙素(OC)、甲状旁腺素(PTH)进行监测.用稳态模式(HOMA)计算胰岛素抵抗指数(IR=FBG×FINS/22.5)、胰岛β细胞分泌指数[IS=20×FINs/(FBG-3.5)1.结果 BMI≥25的肥胖男童BMD、OC明显低于正常对照组(P<0.01),而FBG、FINS、HOMA-IR、DTH、ALP均显著高于正常对照组(P<0.01);经双变量相关分析,BMD分别与BMI、FINS及HOMA-IR呈负相关(r=-0.50,r5=-0.58、-0.60,P均<0.01),与OC呈正相关(r=0.63,P<0.01).结论 严重肥胖男童存在明显的骨代谢异常,且与肥胖程度、高胰岛素血症和胰岛素抵抗密切相关.     

高敏C反应蛋白水平与肥胖及糖代谢异常儿童相关因素的研究

目的 了解高敏C反应蛋白（hs-CRP）与肥胖及糖代谢异常儿童的体量指标及血清参数相关性;探讨hs-CRP与儿童肥胖患者及糖尿病或糖代谢异常的关系。方法 选择肥胖儿童70例作为研究对象,并选择正常儿童30例作为对照组（组1）,根据OGTF试验将肥胖儿童分为不伴糖代谢异常组54例（组2）和糖代谢异常组16例（组3）,测定体量指标及相关参数。结果 肥胖儿童hs-CRP水平2．44（0．01～14．6）mg／L,明显高于对照组[0．1（0．01-2．1）mg／L]。血糖和血脂于正常范围时,肥胖儿童的hs-CRP水平为2．4（0．01-9．0）mg／L,胰岛素抵抗指数（IRI）明显升高。糖脂代谢异常时,hs-CRP水平为2．6（0．1-14．6）mg／L。Pearson相关分析显示,血清hs-CRP水平与BMI、腰围、臀围、腰臀比呈正相关,其中与BMI的相关性最强,多元线性回归分析示,BMI是惟一与hs-CRP相关的指标。结论 肥胖儿童存在低度炎症状态和胰岛素抵抗。hs-CRP与BMI独立相关。hs-CRP和胰岛素抵抗指数的异常升高早于血糖和血脂,hs-CRP增高对糖脂代谢的异常有较好的预测能力。     

Insulin: the other anabolic hormone of puberty

To determine the effect of puberty on isulin action, we used the euglycaemic-hyperinsulinaemic clamp technique in combination with stable isotopes and indirect calorimetry in lean preadolescents, adolescents and; adults. These studies indicated that the insulin resistance induced by normal puberty alters glucose metabolism but is insufficient to adversely affect insulin-stimulated protein metabolism or to inhibit lipolysis. Using the hyperglycaemic clamp technique, we evaluated the impact of the insulin resistance on insulin secretion in pre-adolescents, adolescents and young adults. These studies revealed that the insulin and C-peptide responses to a standardized intravenous hyperglycaemic stimulus were two-to threefold greater in adolescents than in preadolescent children and adults. As growth hormone (GH), insulin-like growth factor 1 (IGF-1) and insulin levels normally peak during puberty, we examined the influence of insulin on IGF-1 regulation by measuring basal GH, total and free IGF-I, and IGF binding protein (IGFBP) levels in lean adolescents and young adults. During the clamp studies, the adolescents exhibited low levels of IGFBP-1 and -2 as well as a reduced insulin-induced suppression of IGFBP-1, compared with lean adults. Thus, we postulate that the insulin resistance of puberty induces compensatory hyperinsulinaemia, which in turn suppresses circulating levels of IGFBP-1, which in turn leads to increased levels of free IGF-I.     

Glucose metabolism and insulin secretion in children with cyanotic congenital heart disease

The aim of the study was to reveal differences in carbohydrate metabolism in children with cyanotic congenital heart diseases (CHD). Thirteen children with diseases of these kinds were investigated with regard to glucose tolerance and insulin secretion and comparisons were made with healthy controls of the same age. Investigations included an intravenous glucose tolerance test, insulin response to the glucose load in plasma and insulin secretion rate. The results reveal lower fasting glucose levels and signs of a higher insulin secretion rate in the relatively few patients in the CHD group where C-peptide measurements were performed, but no differences in glucose tolerance. The reasons for the differences are unclear, but the chronic increases in circulating catecholamines in combination with the impaired nutritional status of these children with CHD are probably the most important factors. We conclude that these divergences in carbohydrate metabolism should be emphasized in the care of children with CHD.     

Physiological Role of Growth Hormone in Adult Life

Salomon, F. and Sonksen, P. H. (Department of Medicine, St Thomas's Hospital, London, UK). Physiological role of growth hormone in adult life. Acta Paediatr Scand [Suppl] 337:158, 1987.
Some historical background on the physiological effects of pituitary gland extract and later of purified hGH in experimental animals is given, and the regulatory role of hGH in the human adult is reviewed. The effects of hGH on Carbohydrate, protein and lipid metabolism are complex and closely linked to the action of other hormones, particularly insulin.     

Protein metabolism in preterm infants with particular reference to intrauterine growth restriction

There is growing evidence that neonatal and long-term morbidity in preterm infants, particularly those born before 32 weeks' gestation, can be modified by attained growth rate in the neonatal period. Guidelines for optimal growth and the nutritional intakes, particular of protein, required to achieve this are not well defined. Due to delays in postnatal feeding and a lack of energy stores developed in the last trimester of pregnancy, preterm infants often suffer early postnatal catabolism until feeding is established. There are indications that infants born with intrauterine growth restriction have perturbations in protein metabolism. Therefore, they may have different protein requirements than appropriate for gestational age infants. This review summarises what is known about protein requirements and metabolism in the fetus and preterm infant, with particular emphasis on the distinct requirements of the growth-restricted infant.     

Growth in relation to protein intake of low birth weight infants

In a prospective longitudinal study of 48 very low birth weight and preterm infants with mean birth weight 1385 ± 343 g and gestational age 30.8 ± 2.9 weeks an assessment was made of the impact of varying the protein intake in the postnatal period from the 3rd to 7th week of life. The infants were randomly allocated to one of three dietary groups with isocaloric energy supply but different protein content, i.e. human milk (1.6 g/100 kcal), formula 1 (2.3 g/100 kcal) and formula 2 (3.0 g/100 kcal). In the human milk group 12 of 18 infants were fed their own mother's breastmilk.During the study period the mean weight gain was slightly higher in the infants red formula. There were no group differences in S-albumin but B-urea-N and B-base deficit were significantly higher in formula-fed infants compared to infants red human milk.After the study period that lasted to about 20 weeks of age the slope in weight gain remained slightly higher for formula fed infants, whereas the gain in body length and head circumference was equal in all three groups. After around 8 months of age there was no difference in any growth parameter. Neurodevelopmental examinations showed no group differences during the follow-up period to 2 years of age.With few exceptions breastmilk-preferably from their own mothers-was adequate for both early and longterm growth and development of the very low birth weight infants in this population.     

Cerebral energy metabolism in insulin induced hypoglycemia in newborn piglets: in vivo31P-nuclear magnetic resonance spectroscopy

The effect of insulin induced hypoglycemia on cerebral energy metabolism was examined in four newborn piglets. Cerebral energy metabolism was assessed using in vivo ³¹P-nuclear magnetic resonance spectroscopy. It was demonstrated that the normal level of phosphocreatine/inorganic phosphate (PCr/Pi), an indicator of phosphorylation potential, was maintained at a blood glucose level of 40 mg/dL or above, whereas when blood glucose was reduced to less than 40 mg/dL, PCr/Pi rapidly decreased in parallel with this. Below the critical blood glucose level of 40 mg/dL, a positive correlation (y = 0.02x + 0.632; r = 0.668; P < 0.001) existed between blood glucose and PCr/Pi. In the present investigation, a reduction of blood glucose level to 20 mg/dL or lower resulted in a PCr/Pi of less than 1, indicating a state of cerebral energy failure. The intracellular pH (pHi) was 7.08 ± 0.05 at the onset and 7.15 ± 0.07 in the hypoglycemic state, indicating no significant difference between the two groups. The present study has clarified that cerebral energy failure occurs when the blood glucose level is about 20 mg/dL or lower. The critical point of blood glucose exists to maintain brain energy metabolism.     

Effect of insulin with oral nutrients on whole-body protein metabolism in growing pubertal children with type 1 diabetes

Insulin treatment of children with insulin-dependent diabetes mellitus improves whole body protein balance. Our recent study, conducted in pubertal children with type 1 diabetes with provision of both insulin and amino acids, indicated a positive effect of insulin on protein balance, primarily through decreased protein degradation. The current study was undertaken to assess the effect of insulin on protein metabolism in adolescents with type 1 diabetes during oral provision of a complete diet. Whole-body protein metabolism in six pubertal children (13-17 y) with type 1 diabetes mellitus was assessed with L-[1-13C]leucine during a basal (insulin-withdrawn) period and during infusion of 0.15 U/kg/h regular insulin with hourly meals to meet protein and energy requirements. Net leucine balance was significantly higher with insulin and nutrients (13.1 +/- 6.3 micromol leucine/kg/h) than in the basal state (-21.4 +/- 2.8, p < 0.01) with protein degradation decreased from 138 +/- 5.6 mumol leucine/kg/h to 108 +/- 5.9 (p < 0.01) and no significant change in protein synthesis. Even with an ample supply of nutrients, insulin does not increase whole-body protein synthesis in pubertal children with type 1 diabetes mellitus and positive protein balance is solely due to a substantial reduction in the rate at which protein is degraded.     

新生儿肺炎能量代谢测定研究

为探讨新生儿肺炎能量代谢的规律 ,应用开放式间接能量测定仪对15例新生儿肺炎患儿进行睡眠代谢率 (SMR)测定 ,并对19例新生儿肺炎患儿进行静息能量消耗 (REE)测定。结果显示 :新生儿肺炎SMR为166.1±24.1kJ/(kg·d) ,与测定时的体重、体表面积、预测值均呈显著相关关系 ;其REE为171.7±30.3kJ/(kg·d),与肺炎病理状况有关。研究表明 :新生儿肺炎能量代谢有其特殊性 ,进行具体测定对患儿合理的营养支持非常必要     

Endocrine control and disturbances of calcium and phosphate metabolism in children

Most disorders of extracellular calcium and phosphate metabolism in childhood can be attributed to primary increased or decreased secretion/action of 1,25-dihydroxyvitamin D₃ and parathyroid hormone or primary increased or decreased urinary excretion of phosphate and calcium. Based on this pathogenetic classification the most important diseases related to calcium and phosphate metabolism will be discussed.Abbreviations PTH parathyroid hormone - 1,25(OH)₂D₃ 1,25-dihydroxyvitamin D₃ - 25(OH)D₃ 25-hydroxyvitamin D₃ - 24,25(OH)₂D₃ 24,25-dihydroxyvitamin D₃ - VDR vitamin D deficiency rickets - VDDR vitamin D dependency rickets - MEN multiple endocrine neoplasia - HP hypoparathyroidism - PHP pseudohypoparathyroidism - AHO Albright's hereditary osteodystrophy - XLH X-linked familial hypophosphataemic rickets     

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??Nutrition support is an essential management of critically ill patients??and enteral nutrition conforms to the physiological state of the body??which can maintain the integrity of intestinal mucosal structure and function??thus ensure the enough intake of calories and protein and preventing the risk of intestinal bacterial translocation effectively. Endoscope-guided placement of feeding tubes is a kind of simple??direct and accurate method to establish enteral nutrition in clinic. The method has high success rate??relatively simple operation. Thus??it is a safe and effective treatment for enteral nutrition, which is worthy of clinical application.     

On the pathogenesis of anticonvulsant-drug-induced alterations of calcium metabolism

Conclusion Recent investigations have illuminated the pathogenesis of anticonvulsant-drug-induced alterations of calcium metabolism. Antiepileptic drugs may provoke renal conservation of calcium and phosphate and possibly compensate partly other of the above mentioned negative effects on calcium and bone metabolism. This may explain the relatively low incidence of manifest rickets or osteomalacia despite long-term treatment with drugs that are now well known to interfere with so many improtant factors of calcium homeostasis.Curriculum vitae. Klaus Kruse was born 1943 in Eutin, Germany. Graduation and thesis 1969 at the faculty of Medicine in Kiel, Germany. 1971 and 1972 fellowship at the Institute of Medical Molecular Biology of the Medical Academy of Lübeck, Germany. Postgraduate training in Pediatrics at the Children's Hospital of the Medical Academy Lübeck (Director: Prof. H. G. Hansen). Since 1974 clinical training at the Children's Hospital of the University of Kiel under Prof. H.-R. Wiedemann and Prof. J. Schaub. Main research interest: Pediatric endocrinology, especially disorders of calcium and carbohydrate metabolism. Member of the European Society for Pediatric Research since 1981. Recipient of a stipend from the German Research Council (studies on the pathogenesis of idiopathic hyperaclciuria and anticonvulsant bone disease).     

Measurement of resting energy expenditure in infants

OBJECTIVE: The method for measurement of basal metabolic rate (BMR) using indirect calorimetry in adults is well established but is impractical in infants. METHODS: In this prospective study energy expenditure was measured using indirect calorimetry in 14 infants when sleeping and when lying quietly awake. RESULTS: Sleeping metabolic rate (SMR) was lower than energy expenditure (EE) measured in the same infants in a quiet resting state (mean difference [SD]: 297 [162] kJ/d; P < 0.005; 55 [33.4] kJ/kg per day; P < 0.005). The correlation within individuals suggests that these differences are related to the level of arousal. Awake EE, but not SMR, was significantly greater than estimated BMR using the FAO/WHO/UNU predictive equation. CONCLUSIONS: In infants, the level of arousal during measurement of EE can significantly impact on the interpretation of EE results. A standardized method for the measurement of EE in infants using indirect calorimetry is proposed.