新型氨基酸制剂对创伤大鼠血游离氨基酸的影响

观察了富含牛磺酸 (Tau)、谷氨酰胺 (Gln)以及高支链氨基酸 (HBCAA)的新型氨基酸制剂对创伤大鼠血中游离氨基酸浓度的影响。结果表明 ,创伤后三天起 ,血浆游离氨基酸总和均显著降低 ,对照组基本无改变 ;创伤后Tau、BCAA、精氨酸以及天冬氨酸等具有抗氧化和免疫调节作用的氨基酸含量明显降低 ,新处方使用一周后其浓度有效回升 ,且效果好于 17种氨基酸 ,从而有利于机体伤口的愈合。这些结果为进一步阐明复合氨基酸制剂促进创伤愈合的作用及其开发应用提供了理论依据     

复方高支链氨基酸对肝硬化大鼠肝功能及营养状况的影响

将SD雄性大鼠用四氯化碳处理建立肝硬化大鼠模型,并随机分为A、B、C三组,A组大鼠给予静脉输注生理盐水,B组、C组大鼠分别给予输注等量的普通氨基酸注射液和复方高支链氨基酸注射液,分别于实验第0d、第14d测定大鼠体质量、肝功能指标及营养学指标水平。实验结束后,B、C两组大鼠体质量明显增加,与A组相比,B、C两组大鼠肝功能各指标水平显著降低,血清蛋白水平显著升高,且C组相比,B组大鼠肝功能水平与血清蛋白水平改善作用更为明显(p<0.05)。说明复方高支链氨基酸能改善肝硬化大鼠的肝功能指标,抑制血浆蛋白分解,有效控制肝硬化病症的进一步恶化。     

烧伤患者血浆和红细胞游离氨基酸变化及输注氨基酸对其变化的影响

动态测定烧伤患者血浆及红细胞内游离氨基酸的含量 ,探讨输入外源性氨基酸后对血及红细胞内游离氨基酸的影响。以日立 835— 5 0型氨基酸自动分析仪测定烧伤患者血浆及红细胞内游离氨基酸含量。结果发现烧伤患者血浆总游离氨基酸浓度从伤后到 2 1天均显著降低 (P <0 .0 5～ 0 .0 1) ;赖、苯丙和苯丙 酪氨酸比值显著升高 (P <0 .0 5～ 0 .0 1) ;色、组、精、丙、甘、苏、脯和丝氨酸比值显著降低 (P <0 .0 5～ 0 .0 1) ;缬、亮、异亮、酪、胱和支链氨基酸伤后早期降低。烧伤患者红细胞内总游离氨基酸含量不同程度降低 ,其中 1、3、7天降低显著 (P <0 .0 5～ 0 .0 1) ;红细胞内苯丙和苯丙 酪氨酸比值未见显著性升高 ;色、蛋、精、脯氨酸含量很低或基本未测出。输注复合氨基酸注射液后未能显著改善患者血及红细胞内游离氨基酸含量。结果提示烧伤患者红细胞内游离氨基酸含量的变化趋势与血浆游离氨基酸变化趋势基本一致 ;烧伤后红细胞内苯丙氨酸及苯丙 酪氨酸比值有别于血浆变化。本研究条件下补充外源性氨基酸未能显著改变烧伤患者血浆及红细胞内游离氨基酸的含量     

富含BCAA 的PN 对肝硬化大鼠肝部分切除术后肝脏NK 的影响

目的:探讨富含支链氨基酸的肠外营养对肝硬化大鼠肝部分切除术后肝脏自然杀伤细胞(NK细胞)的影响。方法:20只肝硬化大鼠随机分为肝部分切除术后行8.5%Novamin的肠外营养5 d组10只,肝部分切除术后行10%Hepa的肠外营养5 d组10只。应用流式细胞仪测定大鼠肝脏NK细胞的百分率;应用4小时51Cr释放法测定肝脏NK细胞的杀伤活性。结果:与8.5%Novamin的肠外营养5 d组比较,10%Hepa的肠外营养5 d组肝脏NK细胞占全部淋巴细胞的百分比和肝脏NK细胞杀伤活性明显升高(P<0.05)。结论:富含支链氨基酸的肠外营养可以增加肝脏NK细胞的百分率和肝脏NK细胞的杀伤活性。     

大豆蛋白对急性放射性肠炎大鼠血清氨基酸的影响

为确定大豆蛋白对急性放射性肠炎大鼠血清氨基酸的影响 ,用SD大鼠复制急性放射性肠炎动物模型 ,给予含大豆蛋白饲料 ,测量血清氨基酸含量。结果显示 :使用大豆蛋白后细菌移位率显著降低 ,血LPS含量和肠通透性均未见升高 ,回肠绒毛高度、肠全层厚度和粘膜厚度均高于实验对照组 ,血清谷氨酰胺和支链氨基酸的含量均显著高于对照组。说明大豆蛋白使大鼠血清谷氨酰胺和支链氨基酸的含量明显升高 ,可以提高急性放性射肠炎时的肠屏障功能。     

急性肝损伤大鼠模型的血浆氨基酸代谢变化模式

以Ｄ－氨基半乳糖（Ｄ－Ｇａｌａｃｔｏｓａｍｉｎｅ,Ｄ－ＧａｌＮ）造成急性肝损伤（急性肝炎、急性肝坏死）大鼠模型后、对照观察了急性肝损伤大鼠血浆氨基酸的变化,建立了大鼠急性肝损伤时血浆氨基酸的变化模式并对其发生机理进行了探讨。大鼠血浆氨基酸的测定采用聚酰薄层荧光分析技术,其测定结果是：急性肝炎组,酪氨酸（Ｔｙｒ）、天冬氨酸（Ａｓｐ）、谷氨酰胺（Ｇｌｎ）和鸟氨酸（Ｏｒｎ）升高,精氨酸（Ａｒｇ）下降,其余氨基酸无显著变化。急性肝坏死组,除Ａｒｇ显著下降外,其余所有氨基酸都显著升高,而两组支链氨基酸（ＢＣＡＡ）／芳香族氨基酸（ＡＡＡ）克分子比值均显著下降。     

圈养大熊猫粘液水解氨基酸含量的初步研究

收集了成都大熊猫繁育研究基地的 8只圈养大熊猫的 12个粘液样品并测定了其中 17种水解氨基酸(AA)的含量。结果如下 :粘液干物质中Glu含量最高 ,为 9 2 4 %± 0 4 7% ,其次为Leu、Asn、Thr、Ser、Pro、Val、Lys、Ala、Tyr、Arg、Gly、Ile、Phe、Cys、His,Met含量 (1 2 5 %± 0 18% )最低 ,不同样品中同一种AA的含量不同。样品中 9种非必需氨基酸 (NEAA)的总平均含量为 4 1 1%± 2 2 % ,8种必需氨基酸(EAA)的总平均含量为 2 9 8%± 1 8% ,NEAA/EAA的平均值为 1 38± 0 0 4 ,不同粘液样品的这些数值相近。不同样品中同一种EAA与该样品中Lys含量的比值存在不同程度的差异 ,样品中 (Tyr Phe) /Lys值最高 ,为1 79± 0 31;其次为Leu/Lys和Thr/Lys;而Met/Lys值最低 ,为 0 31± 0 0 5。各种氨基酸相对于总氨基酸含量的高低顺序与各AA绝对含量高低顺序完全相同 ,Glu含量最高为 13 0 %± 0 30 % ,Met含量为 1 76 %±0 2 5 %。结果表明 ,大熊猫粘液样品各种AA特别是EAA含量丰富 ,不同样品含量存在不同程度的差异 ;认为对排粘频繁和每次排粘量大的大熊猫 ,必须补充适量的优质蛋白以弥补由粘液排泄而造成的损失 ,以促进其体况的尽快恢复。     

高效液相色谱法测定17AA氨基酸注射液中N-乙酰-L-半胱氨酸和N-乙酰-L-酪氨酸

建立了一种用高效液相色谱测定 17AA氨基酸注射液中N 乙酰 L 半胱氨酸和N 乙酰 L 酪氨酸含量的方法。样品经稀释后 ,直接上机测定 ,其色谱条件为 :WatersSymmetryC18色谱柱 ,流动相为 8.5mmol/LNaAc - 5 %CH3 OH (pH =4.0 ) ,柱温36℃ ,流速 1.0ml/min ,检测波长 195nm ,N 乙酰 L 半胱氨酸在 5 .4mg/L到 5 40mg/L、N 乙酰 L 酪氨酸在 4.9mg/L到 490mg/L之间 ,标准曲线呈良好的线性关系 (r2 >0 .9999)。该方法具有良好的重现性 ,日内相对标准偏差小于 3% ,日间相对平均误差小于 7% ,样品回收率在 90 %～ 110 %之间。该方法与测定氨基酸注射液的其它高效液相色谱法相结合 ,能够对 17AA氨基酸注射液中所有氨基酸成分进行全面检测。     

谷氨酰胺活性肽营养液对大鼠小肠营养作用的研究

用氨甲蝶呤诱发小肠炎后 ,SD大鼠分别饲喂Gln含量不等的氨基酸营养液 ,结果表明 ,72h内 ,第一组 (零剂量组 )大鼠的死亡率为 6 6 .7% ,第二组 (含Gln质量分数 2 % )为 16 .7% ,第三组 (活性肽组 ,含Gln质量分数 2 0 % )和第四组 (结晶氨基酸液 ,含Gln质量分数 2 0 % )为 0 ,并且第三组和第四组的体重、蔗糖酶活、氨肽酶活、DNA和RNA的含量增加 ,说明Gln活性肽营养液对小肠具有明显的营养作用。     

心血瘀阻与气阴两虚证心肌缺血大鼠模型的代谢组学表征与辨识

本实验建立了心血瘀阻和气阴两虚证心肌缺血大鼠模型,基于气相色谱/飞行时间质谱（GC/TOF-MS）检测技术的代谢组学方法,分析血浆中的内源性小分子代谢物,发现两种中医证和正常大鼠之间代谢图谱存在明显差异,数据处理和模式识别后各组可被清晰地区分.与正常大鼠相比,模型大鼠血浆中羟脯氨酸、苏糖酸、谷氨酰胺、柠檬酸等化合物的相对含量发生了显著变化.两种“证型”大鼠间血浆中缬氨酸、丝氨酸、苏氨酸、鸟氨酸、羟脯氨酸、赖氨酸、2-羟基丁酸、3-羟基丁酸、呋喃半乳糖、肌醇等化合物的相对含量存在显著差异,这些化合物是区分这两种中医证型的潜在生物标志物.研究结果提示,这两种证型与能量代谢异常、氧化应激反应、氨基酸代谢异常等体内变化密切相关.此发现为探索这两种基于心肌缺血的中医证的科学内涵、病理机制及科学“辨证”提供了研究基础.     

Glutamine synthesis in the developing porcine placenta

Glutamine plays a vital role in fetal carbon and nitrogen metabolism and exhibits the highest fetal:maternal plasma ratio among all amino acids in pigs. Such disparate glutamine levels between mother and fetus suggest that glutamine may be actively synthesized and released into the fetal circulation by the porcine placenta. We hypothesized that branched-chain amino acid (BCAA) metabolism in the placenta plays an important role in placental glutamine synthesis. This hypothesis was tested by studying conceptuses from gilts on Days 20, 30, 35, 40, 45, 50, 60, 90, or 110 of gestation (n = 6 per day). Placental tissue was analyzed for amino acid concentrations, BCAA transport, BCAA degradation, and glutamine synthesis as well as the activities of related enzymes (including BCAA transaminase, branched-chain alpha-ketoacid dehydrogenase, glutamine synthetase, glutamate-pyruvate transaminase, and glutaminase). On all days of gestation, rates of BCAA transamination were much greater than rates of branched-chain alpha-ketoacid decarboxylation. The glutamate generated from BCAA transamination was primarily directed to glutamine synthesis and, to a much lesser extent, alanine production. Placental BCAA transport, BCAA transamination, glutamine synthesis, and activities of related enzymes increased markedly between Days 20 and 40 of gestation, as did glutamine in fetal allantoic fluid. Accordingly, placental BCAA levels decreased after Day 20 of gestation in association with a marked increase in BCAA catabolism and concentrations of glutamine. There was no detectable catabolism of glutamine in pig placenta throughout pregnancy, which would ensure maximum output of glutamine by this tissue. These novel results demonstrate glutamine synthesis from BCAAs in pig placentae, aid in explaining the abundance of glutamine in the fetus, and provide valuable insight into the dynamic role of the placenta in fetal metabolism and nutrition.     

Regulation of RNA degradation in cultured rat hepatocytes: Effects of specific amino acids and insulin

The regulation of RNA degradation by specific amino acids and insulin was investigated in cultured rat hepatocytes from fed rats previously injected in vivo with [6-¹⁴C]orotic acid. The effects of three groups of amino acids were compared to those of a complete amino acid mixture. The first one consisted of the eight amino acids (leucine, proline, glutamine, histidine, phenylalanine, tyrosine, methionine, tryptophan) previously found to be particularly effective in the control of proteolysis. The two other groups were defined from our study with single additions of amino acids, one consisting of proline, asparagine, glutamine, alanine, phenylalanine, and leucine and the other including the latter group with serine, histidine, and tyrosine. The results showed that these three groups were able to strongly inhibit deprivation-induced RNA breakdown at one and ten times normal plasma concentrations but to a lower extent than the complete amino acid mixture. Six amino acids (proline, asparagine, glutamine, alanine, phenylalanine, leucine) inhibited individually RNA degradation by more than 20%. However, the deletions of proline, asparagine, glutamine, or alanine from the group of these six amino acids were not followed by a loss of inhibitory effect. On the contrary, an important loss of inhibition was observed when leucine and phenylalanine were deleted. Furthermore, only these two amino acids exhibited an additive inhibitory effect. Thus leucine and phenylalanine could be considered as important inhibitors of RNA breakdown in cultured rat hepatocytes. Finally, insulin which had no significant effect on RNA degradation in the absence of amino acids, was able to potentiate the inhibitory effect of different amino acid groups. © 1993 Wiley-Liss, Inc.     

Plasma amino acid patterns in hepatocellular carcinoma

Plasma amino acid levels were determined in 23 patients in comparison with 16 normal subjects and 17 patients with liver cirrhosis. Patients with hepatocellular carcinoma had elevated levels of the aromatic amino acids and lowered levels of the branched-chain amino acids, as seen in liver cirrhosis; however, they had lowered levels of alanine and glutamine as compared with normal subjects and with liver cirrhosis patients. Following treatment with intraarterial chemotherapy and/or transcatheter arterial embolization, plasma levels of alanine and glutamine recovered. These results suggest that the consumption of alanine and glutamine increase in hepatocellular carcinoma.     

烫伤大鼠早期口服谷氨酰胺对血浆氨基酸代谢的影响

研究烫伤早期口服谷氨酰胺 (GLN)后GLN及其相关氨基酸的代谢变化。以Wistar大鼠为烫伤模型 ,烫伤后早期口服GLN ,并以 83 5-50型氨基酸自动分析仪的生理体液法测定血浆游离氨基酸。结果烫伤后饲标准饲料(C)组血浆GLN在烫伤后 2d和 5d降低 ,与GLN代谢相关的丙氨酸和氨无显著性变化 ;GLN饲料 (G)组各时相点GLN均增加 ,1 0h和 8d增加显著 ,与GLN代谢相关的丙氨酸和血氨增加显著 ;GLN +精氨酸 (G +A)组GLN在 2d降低 ,血氨升高显著。与C组比 ,G和G +A组血浆总氨基酸、支琏氨基酸、GLN、丙氨酸、r-氨基丁酸和氨均较C组高。提示 ,烫伤后早期口服GLN能提高血GLN和与之代谢相关的氨基酸浓度。     

The effects of starvation and refeeding on plasma amino acid levels in carp, Cyprinus carpio L., 1758

Plasma amino acid (AA) levels of carp, Cyprinus carpio L., 1758, were analysed after various periods of starvation as well as after 12 days of refeeding. The levels were compared to control groups, which had been previously fasted for 24 h. A positive correlation between dietary and plasma essential amino acid (EAA) concentrations was observed in all of the control groups.
The effect of starvation on the dynamics of AA concentration was different according to the period of starvation. Fasting already produced a decrease of total α-AA levels at 2 days, and these low levels were maintained until 5 and 8 days. These short periods of fasting affected the levels of EAA (especially branched-chain AA) more than those of non-essential amino acids (NEAA). The only AA that increased was Ala, which rose at 5 days of starvation, surpassing the levels of the control group. These high levels were maintained until 19 days of starvation.
A different situation was observed at 19 days, when an important increase of total α-AA levels was produced, the branched-chain AA being the most notable among EAA and Glu/Gln among NEAA. Later, at 50 days of starvation, total α-AA, EAA (except Leu and Ile) and NEAA decreased.
After 50 days of starvation, 12 days of refeeding did not modify the levels of EAA and NEAA, and their concentrations were lower than those of the control group, which presented an increase of total AA at this time. The differences observed on the changes of individual AA levels are discussed.     

Combination of BCAAs and glutamine enhances dermal collagen protein synthesis in protein-malnourished rats

Skin collagen decreases in protein-malnourished states. Amino acids regulate protein metabolism, glutamine stimulates collagen synthesis through the conversion process to proline and provides 75 % of the intracellular free proline in fibroblasts. However, the impact of these amino acids on collagen synthesis under malnutrition has not been examined. We investigated the effect of amino acids on dermal tropocollagen synthesis in protein-malnourished rats. The fractional synthesis rate (FSR, %/h) of dermal tropocollagen was evaluated by the incorporation of l-[ring-²H₅]-phenylalanine after 4 h infusion of each amino acid and the stable isotope. None of the infused 12 single amino acids (glutamine, proline, alanine, arginine, glutamate, glycine, aspartate, serine, histidine, lysine, phenylalanine and threonine) significantly increased the FSR (P = 0.343, one-way ANOVA). In contrast, amino acid mixtures of essential amino acids + glutamine + arginine (EAARQ) and branched-chain amino acids + glutamine (BCAAQ) significantly increased the FSR compared to saline, but the branched-chain amino acids (BCAAs) and amino acid mixture of collagen protein (AAC) did not alter the FSR (saline, 0.96 ± 0.24 %/h; EAARQ, 1.76 ± 0.89 %/h; BCAAQ 1.71 ± 0.36 %/h; BCAAs, 1.08 ± 0.20 %/h and AAC 1.39 ± 0.35 %/h, P < 0.05, Tukey’s test). Proline conversion from glutamine represented only 3.9 % of the free proline in skin, as evaluated by the primed-constant infusion of l-d7-proline and l-α-15N-glutamine in rats. These results suggested that the combination of BCAAQ is a key factor for the enhancement of skin collagen synthesis in protein-malnourished rats. The contribution of extracellular free glutamine on de novo proline synthesis and collagen synthesis is very low in vivo compared to the contribution in vitro.     

Amino acid metabolism in the Zucker diabetic fatty rat: effects of insulin resistance and of type 2 diabetes

We investigated amino acid metabolism in the Zucker diabetic fatty (ZDF Gmi fa/fa) rat during the prediabetic insulin-resistant stage and the frank type 2 diabetic stage. Amino acids were measured in plasma, liver, and skeletal muscle, and the ratios of plasma/liver and plasma/skeletal muscle were calculated. At the insulin-resistant stage, the plasma concentrations of the gluconeogenic amino acids aspartate, serine, glutamine, glycine, and histidine were decreased in the ZDF Gmi fa/fa rats, whereas taurine, alpha-aminoadipic acid, methionine, phenylalanine, tryptophan, and the 3 branched-chain amino acids were significantly increased. At the diabetic stage, a larger number of gluconeogenic amino acids had decreased plasma concentrations. The 3 branched-chain amino acids had elevated plasma concentrations. In the liver and the skeletal muscles, concentrations of many of the gluconeogenic amino acids were lower at both stages, whereas the levels of 1 or all of the branched-chain amino acids were elevated. These changes in amino acid concentrations are similar to changes seen in type 1 diabetes. It is evident that insulin resistance alone is capable of bringing about many of the changes in amino acid metabolism observed in type 2 diabetes.     

Traumatic Brain Injury-Induced Excitotoxicity Assessed in a Controlled Cortical Impact Model

Using a controlled cortical impact model of traumatic brain injury (TBI) coupled with tissue microdialysis, interstitial concentrations of aspartate and glutamate (together with serine and glutamine) were assessed in rat frontal cortex. Histological analysis indicated that the severity of injury following severe TBI (depth of deformation = 3.5 mm) was approximately twice that occurring following moderate TBI (depth of deformation = 1.5 mm). Both groups demonstrated significant postinjury maximal increases in excitatory amino acid (EAA) concentration, which were proportional to the severity of injury. The mean ± SEM fold increase in dialysate concentrations of aspartate was 38 ± 13 (n = 5) for moderate TBI and 74 ± 12 (n = 5) for severe TBI. Fold increases in glutamate concentrations were 81 ± 26 and 144 ± 23 for moderate and severe TBI, respectively. Although these increases normalized within 20–30 min following moderate TBI, concentrations of aspartate and glutamate took >60 min to normalize after severe TBI. Changes in levels of nontransmitter amino acids were much smaller. Fold increases for serine concentrations were 4.6 ± 0.6 and 7.6 ± 1.7 in moderate and severe TBI, respectively; glutamine concentrations had similar small fold increases (2.6 ± 0.2 and 4.1 ± 0.6, respectively). Calculation of interstitial concentrations following severe TBI indicated that aspartate and glutamate maximally increased to 123 ± 20 and 414 ± 66 μM, respectively. To determine the extent to which such tissue concentrations of EAAs could contribute to the injury seen in TBI, the EAA receptor agonists N-methyl-d - aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid were slowly injected into rat cortex. Remarkably similar histological injuries were produced by this procedure, supporting the notion that TBI is an excitotoxic injury.     

Amino acid catabolism by perfused rat hindquarter. The metabolic fates of valine.

Hindquarters from starved rats were perfused with plasma concentrations of amino acids, but without other added substrates. Release of amino acids was similar to that previously reported, but, if total amino acid changes were recorded, alanine and glutamine were not formed in excess of their occurrence in muscle proteins. In protein balance (excess insulin) there was no net formation of either alanine or glutamine, even though the branched-chain amino acids and methionine were consumed. If [U-14C]valine was present, radiolabelled 3-hydroxyisobutyrate and, to a lesser extent, 2-oxo-3-methylbutyrate accumulated and radiolabel was incorporated into citrate-cycle intermediates and metabolites closely associated with the citrate cycle (glutamine and glutamate, and, to a smaller extent, lactate and alanine). If a 2-chloro-4-methylvalerate was present to stimulate the branched-chain oxo acid dehydrogenase, flux through this step was accelerated, resulting in increased accumulation of 3-hydroxyisobutyrate, decreased accumulation of 2-oxo-3-methylbutyrate, and markedly increased incorporation of radiolabel (specific and total) into all measured metabolites formed after 3-hydroxyisobutyrate. It is concluded that: amino acid catabolism by skeletal muscle is confined to degradation of the branched-chain amino acids, methionine and those that are interconvertible with the citrate cycle; amino acid catabolism is relatively minor in supplying carbon for net synthesis of alanine and glutamine; and partial degradation products of the branched-chain amino acids are quantitatively significant substrates released from muscle for hepatic gluconeogenesis. For valine, 3-hydroxyisobutyrate appears to be quantitatively the most important intermediate released from muscle. A side path for inter-organ disposition of the branched-chain amino acids is proposed.