稳定同位素技术在组织蛋白质代谢研究中的应用

总体蛋白质代谢不能反映机体特定器官组织的蛋白质代谢情况,因此需要对组织蛋白质代谢进行研究。本文介绍了稳定同位素示踪技术在组织蛋白质代谢研究中的应用原理、主要方法和研究进展,并分析了各种方法的优点和局限性。     

O11 稳定同位素技术及其在钙代谢研究中的应用

稳定同位素技术是一种应用钙稳定同位素来研究待测钙源在体内代谢情况的方法.该法具有安全、准确、操作简便等特点,尤其适于儿童青少年、孕妇和乳母的钙代谢研究.目前,该技术已成为测定钙吸收率的最佳选择.此外,在钙需要量研究和钙代谢动力学研究等领域,该技术的应用也逐渐增多.不过,昂贵的价格和复杂的检测方法始终是制约该技术广泛应用的主要因素.     

稳定同位素技术及其在钙代谢研究中的应用

稳定同位素技术是一种应用钙稳定同位素来研究待测钙源在体内代谢情况的方法。该法具有安全、准确、操作简便等特点，尤其适于儿童青少年、孕妇和乳母的钙代谢研究。目前，该技术已成为测定钙吸收率的最佳选择。此外，在钙需要量研究和钙代谢动力学研究等领域，该技术的应用也逐渐增多。不过，昂贵的价格和复杂的检测方法始终是制约该技术广泛应用的主要因素。     

氨基酸代谢动力学研究中坪台期探讨

目的探讨在以稳定同位素标记的氨基酸做为示踪剂研究氨基酸的代谢动力学的过程中,同位素丰度值什么时间达到一个稳定的坪台期。方法选取5名健康成年男性做为研究对象,食用日常膳食5天后,在第6天经静脉给予稳定同位素13C标记的亮氨酸3h,在输液过程中及输注结束后的1h内收集受试者的呼出气样本,测定13C的丰度值,以确定同位素丰度值的坪台期。结果5名受试者的呼出气样品中13C的丰度值在输液结束前的1h内处于一个相对较高的坪台期,在输液结束后丰度值立刻降低。结论利用稳定同位素示踪技术研究氨基酸的代谢动力学,取样的适宜时机是在输注结束前的1h内。     

稳定性同位素示踪技术的蛋白质代谢动力学研究

同位素示踪技术是公认的用于研究蛋白质代谢动力学的最佳方法。起初,由于放射性同位素具有方便、经济、检测技术成熟等优点而得到广泛应用,但因它的放射性限制了在人体代谢研究中的应用。随着稳定性同位素标记技术的成熟和质谱分析技术的发展和普及,稳定性同位素被广泛用于人体代谢动力学研究中。以下就稳定性同位素用于研究蛋白质代谢动力学中的基本原理、方法、检测手段和应用作一综述。     

稳定的同位素标记探针在人体溶剂药物动力学研究中价值

稳定的同位素标记探针在人体溶剂药物动力学研究中价值Ｍ．Ｓ．Ｍｏｒｇａｎｅｔａｌ．本研究的主要目的为：１）对有控制地急性吸入甲苯及其稳定同位素标记的甲苯受检者，确定描述上述化合物的吸收、分布、代谢和排泄的药物动力学参数；２）比较甲苯及同位素标记的甲苯的...     

进食状态下口服~(13)C-亮氨酸呼出气平台期研究

目的探讨在进食状态下口服13C-亮氨酸作为示踪剂进行氨基酸代谢动力学研究时,呼出气中同位素含量在什么时间达到稳定的平台期。方法选取6名健康成年女性作为研究对象,给予日常膳食5天,在第6天持续口服13C-亮氨酸4h,并伴随食物摄入,收集给予同位素过程中及给予结束后1h的呼出气样本,测定13C的千分差值,以确定同位素的平台期。结果6名受试者的呼出气样品中13C的千分差值在口服同位素结束前后各半小时内处于相对较高的平台期,随后逐渐下降。结论在进食状态下口服13C-亮氨酸示踪剂进行氨基酸代谢动力学研究,取样的适宜时间是在给予同位素结束前后各半小时内。     

稳定同位素示踪技术在氨基酸生理需要量研究中的应用

本文简要综述了稳定同位素示踪技术研究氨基酸生理需要量的研究模型、直接氧化法和指示剂氨基酸氧化法的实验原理以及它们在实验中的应用,通过这种方法可以对氨基酸的代谢过程做一动态观察,计算相关的参数,评估各种必需氨基酸的需要量,所得出的相关数值均高于世界卫生组织所给出的数值。     

稳定性同位素技术对锌生物利用率的研究

锌是人体必需微量元素之一 ,锌稳态主要通过改变肠道吸收效率和内源性排泌 ,即调节生物利用率来实现。研究锌的生物利用率对全面理解锌的代谢和可靠评价人群锌营养状况起着重要的作用。稳定性同位素是目前研究矿物元素生物利用和代谢的有效工具。锌的稳定性同位素可以作为示踪物安全应用于所有人群而无放射性危害。自 80年代以来 ,许多不同的稳定性同位素方法被发展起来用以分析锌的吸收代谢 ;然而 ,一些方法学的问题尚待解决。此外 ,分析仪器的发展和应用不仅使锌稳定性同位素的应用成为可能 ,也大大降低了该技术的难度和成本。本文主要对其发展历史、应用特点、主要的研究方法及分析技术做一综述。     

妊娠或哺乳不增加妇女饮食钙需要量

既往研究认为，由于妇女在妊娠和哺乳期消耗钙量大大增加，故应予膳食补充。近年来，由于更新了研究手段，采用了稳定同位素，定量ＣＴ以及双能量Ｘ射线吸收骨密度测定等先进方法，精密测定了骨钙含量的改变，得出了不同的结论。目前研究认为，胎儿及乳汁的钙来自母体代谢改变的结果，而这种代谢改变明显然不受膳食中钙的影响，反映上述最新研究结果的《美国和加拿大膳食指导》修订版明确指出；妊娠及哺乳妇女不需要增加钙的摄入。     

热断层扫描评估血糖代谢的试验研究

目的应用热断层扫描技术（TTM）及空腹血糖检查对血糖异常代谢进行评估与诊断,并比较两种检查方法的吻合度,旨在评价TTM对糖代谢异常的评估应用价值。方法选取行TTM全身检测与空腹血糖检查者16955例,将TTM检测的阳性和阴性与空腹血糖检查诊断的血糖升高和正常这4个参数进行诊断试验（四格表运算）,以取得各项评价指标,并将TIM评估与空腹血糖检查诊断血糖代谢的情况进行X系数检验。对空腹血糖值正常而TIM评估血糖升高的体检者进行4年随访,并统计分析其空腹血糖值的变化。结果TTM对血糖代谢异常的评估特异性较强（75％）,准确度及敏感度分别为71．9％、53．2％;两种诊断方法的吻合系数为κ=0．196,P=0．000〈0．05。结论TTM对血糖代谢异常的早期筛查有一定的应用价值,将其用于健康体检进行疾病的早期筛查,值得我们不断研究和探索。     

Microbial Metabolism of Naringin and the Impact on Antioxidant Capacity

Naringin is a dietary flavonoid glycoside with broad bioactivities, and it has been found to undergo extensive microbial metabolism in human gut. Microbial metabolites are believed to play an important role in the overall bioactivity of naringin. However, knowledge is scarce about its microbial metabolism in laboratory rats, which are the most commonly used animal model for naringin-related biomedical studies. Herein, we profiled the microbial metabolism of naringin in rat by an in vitro anaerobic fermentation combined with LC-MS/MS methods. A total of 35 microbial metabolites were identified, and corresponding metabolic pathways were proposed. Naringin and its metabolites were further quantified in fermentation samples. Rhoifolin, neoeriocitrin, neohesperidin, naringenin, methylated naringin, and hydroxylated naringin were detected as the primary microbial metabolites. Moreover, antioxidant capacity assays suggested that fermentation-associated microbial metabolites exhibited higher antioxidant activity than original naringin. Obtained results contribute to a more comprehensive understanding of the microbial metabolism and antioxidant capacity of naringin.     

乙醛脱氢酶基因型对2-乙氧基乙醇代谢影响的研究

探讨乙醛脱氢酶（ALDH2）不同基因型代谢2－乙氧基乙醇（EE）的能力是否存在差异。方法 采用个体采样,毛细柱气相色谱分析技术及PCR检测方法,比较不同基因型个累计接触EE剂量与2－乙氧基乙酸（EAA）浓度对数值回归直线的回归系数。结果 ALDH2不同基因型个体累计接触EE剂量与EAA浓度对数值存在线性关系,A基因型回归系数大于B基因型。结论 ALDH2A基因型代谢EE能力强于B基因型。     

Methodological approaches to the study of metabolism across individual tissues in man

PURPOSE OF REVIEW: This article is intended to briefly overview available methodological approaches for the study of regional metabolism in man in vivo, and to summarize recent advances in this field of research. RECENT FINDINGS: Several methods have been developed and currently allow for the qualitative and quantitative assessment of energy interconversions and substrate fluxes across individual tissues of man, including the measurement of arteriovenous concentration differences, microdialysis, and nuclear magnetic resonance spectroscopy of carbon, hydrogen, and phosphorus isotopes. Each method alone has been used rather extensively to examine certain aspects of organ and tissue metabolism under a variety of experimental conditions, and has contributed novel information in this regard. The most exciting development appears to be the combined use of more than one investigational technique, across one or more tissues simultaneously. A handful of recent studies have employed complex experimental designs or hybrid methodologies, ultimately demonstrating the potential for a more detailed assessment of metabolism at the local level. SUMMARY: Clearly, advances in the use, performance, and applications of available methods are expected to provide improved and more powerful tools for the metabolic investigation of organs and tissues in humans in vivo.     

Evaluation of the exposure to organic solvent mixture

Summary A comparative study was conducted in a printing plant regarding various methods of measuring environmental concentrations of a solvent vapour mixture, the major components of which were n-hexane, ethyl acetate and toluene. Introduction of a portable gas-liquid chromatograph made it possible to analyze spot-air samples at the site of the exposure, and thereby obtain immediate information on its quality and quantity. The results were compared with those from personal sampling and continuous stationary sampling coupled with gas-liquid chromatographic analysis well as detection tube methods. Spot-air, personal and continuous stationary sampling methods were in good parallel while the detection tube method was less valid in the case of vapour mixture exposure. Studies on toluene metabolism revealed that the biological half-life of toluene was about 7.5 hrs and that the metabolism was not significantly disrupted by the co-presence of other solvents such as ethyl acetate and n-hexane.This work was supported in part by a research grant from the Fujiwara Memorial Foundation, and presented at the 47th Annual Meeting of the Japanese Association of Industrial Health, Nagoya, Japan, March 29–31, 1974.     

Intestinal transit and systemic metabolism of apple polyphenols

Background  

Apples are the most widely consumed fruits in Germany and various other countries. Positive health effects of apple-derived polyphenols in vivo depend on their absorption, metabolism, distribution, and elimination from the body after consumption. Data on the metabolism of these polyphenols in humans are scarce. In order to study the intestinal transit and metabolism of apple polyphenols in humans, a variety of experiments were carried out.     

Methods of measuring metabolism during surgery in humans: focus on the liver-brain relationship

PURPOSE OF REVIEW: The purpose of this work is to review recent advances in setting methods and models for measuring metabolism during surgery in humans. Surgery, especially solid organ transplantation, may offer unique experimental models in which it is ethically acceptable to gain information on difficult problems of amino acid and protein metabolism. RECENT FINDINGS: Two areas are reviewed: the metabolic study of the anhepatic phase during liver transplantation and brain microdialysis during cerebral surgery. The first model offers an innovative approach to understand the relative role of liver and extrahepatic organs in gluconeogenesis, and to evaluate whether other organs can perform functions believed to be exclusively or almost exclusively performed by the liver. The second model offers an insight to intracerebral metabolism that is closely bound to that of the liver. SUMMARY: The recent advances in metabolic research during surgery provide knowledge immediately useful for perioperative patient management and for a better control of surgical stress. The studies during the anhepatic phase of liver transplantation have showed that gluconeogenesis and glutamine metabolism are very active processes outside the liver. One of the critical organs for extrahepatic glutamine metabolism is the brain. Microdialysis studies helped to prove that in humans there is an intense trafficking of glutamine, glutamate and alanine among neurons and astrocytes. This delicate network is influenced by systemic amino acid metabolism. The metabolic dialogue between the liver and the brain is beginning to be understood in this light in order to explain the metabolic events of brain damage during liver failure.     

骨胶原代谢标志物的研究进展

在骨代谢异常疾病的研究中 ,由于骨活检 ,放射学 ,血生化 ,同位素等检测的局限性 ,寻找特异性强 ,重复性好 ,侵入性小的指标日益受到重视。骨胶原是骨组织构成的重要组成部分 ,本文对其标志物的研究进展进行综述。