Diagnostic value of methylated branched chain amino acid transaminase 1/IKAROS family zinc finger 1 for colorectal cancer

BACKGROUND The diagnostic value of combined methylated branched chain amino acid transaminase 1(BCAT1)/IKAROS family zinc finger 1(IKZF1)in plasma for colorectal cancer(CRC)has been explored since 2015.Recently,several related studies have published their results and showed its diagnostic efficacy.AIM To analyze the diagnostic value of methylated BCAT1/IKZF1 in plasma for screening and postoperative follow-up of CRC.METHODS The candidate studies were identified by searching the PubMed,Embase,Cochrane Library,CNKI,and Wanfang databases from May 31,2003 to June 1,2023.Sensitivity,specificity,and diagnostic accuracy were calculated by merging ratios or means.RESULTS Twelve eligible studies were included in the analysis,involving 6561 participants.The sensitivity of methylated BCAT1/IKZF1 in plasma for CRC diagnosis was 60%[95%confidence interval(CI)53-67]and specificity was 92%(95%CI:90-94).The positive and negative likelihood ratios were 8.0(95%CI:5.8-11.0)and 0.43(95%CI:0.36-0.52),respectively.Diagnostic odds ratio was 19(95%CI:11-30)and area under the curve was 0.88(95%CI:0.85-0.91).The sensitivity and specificity for CRC screening were 64%(95%CI:59-69)and 92%(95%CI:91-93),respectively.The sensitivity and specificity for recurrence detection during follow-up were 54%CONCLUSION The detection of methylated BCAT1/IKZF1 in plasma,as a non-invasive detection method of circulating tumor DNA,has potential CRC diagnosis,but the clinical application prospect needs to be further explored.

Branched-chain amino acids in liver diseases

Branched chain amino acids(BCAAs)have been shown to affect gene expression,protein metabolism,apoptosis and regeneration of hepatocytes,and insulin resistance.They have also been shown to inhibit the proliferation of liver cancer cells in vitro,and are essential for lymphocyte proliferation and dendritic cell maturation.In patients with advanced chronic liver disease,BCAA concentrations are low,whereas the concentrations of aromatic amino acids such as phenylalanine and tyrosine are high,conditions that may be closely associated with hepatic encephalopathy and the prognosis of these patients.Based on these basic observations,patients with advanced chronic liver disease have been treated clinically with BCAA-rich medicines,with positive effects.

Impairment of innate immune responses in cirrhotic patients and treatment by branched-chain amino acids

It has been reported that host defense responses, such as phagocytic function of neutrophils and natural killer (NK) cell activity of lymphocytes, are impaired in cirrhotic patients. This review will concentrate on the impairment of innate immune responses in decompensated cirrhotic patients and the effect of the treatment by branched-chain amino acids (BCAA) on innate immune responses. We already reported that phagocytic function of neutrophils was significantly improved by 3-mo BCAA supplementation. In addition, the changes of NK activity were also significant at 3 mo of supplementation compared with before supplementation. Also, Fisher’s ratios were reported to be significantly increased at 3 mo of BCAA supplementation compared with those before oral supplementation. Therefore, administration of BCAA could reduce the risk of bacterial and viral infection in patients with decompensated cirrhosis by restoring impaired innate immune responses of the host. In addition, it was also revealed that BCAA oral supplementation could reduce the risk of development of hepatocellular carcinoma in cirrhotic patients. The mechanisms of the effects will also be discussed in this review article.

Synergistic renoprotective effect of a compiled branched-chain amino acids and Cymbopogon schoenanthus extract against experimentally induced oxido-nitrosative renal insult

Objective: To better investigate the protective role of branched-chain amino acids(BCAAs)and Cymbopogon schoenanthus(CS) extract against the potassium dichromate(PDC)-induced oxido-nitrosative nephrotoxic insult in the experimental rat model. Methods: Thirty male rats were randomly divided into five equal groups: The 1 st group served as control; the 2^(nd)was injected with a single dose of PDC(15 mg/kg b.w i.p.);the 3^(rd), 4^(th), and 5^(th) groups were respectively treated with BCAAs, CS, and their combination for 15 d prior to induction of renal insult via PDC single dose(15 mg/kg b.w s.c.). The experimental period was terminated in all groups 2 d after induction of renal insult. The harvested kdney samples were divided for biochemical assays and histological examination. Results: The PDC-induced nephrotoxic effect caused a depletion of renal oxidative scavengers glutathione, superoxide dismutase with consequent lipo-oxidative cellular membrane deterioration manifested by a rise in malonaldehyde, oxidized glutathione, myeloperoxidase and the concomitant increase in inflammatory response elements tumor necrosis factor α, nitric oxide, and interleukin 1 β.Moreover, the comet assay and increased 8-hydroxy-2-deoxyguanosine proved an accelerated apoptotic DNA fragmentation. These local renal changes were met with global altered blood biochemistry. The BCAAs and CS or their compiled administration showed an ameliorative effect against PDC-induced nephrotoxic in a synergistic pattern. Conclusions: Both BCAAs and CS or their combined administration afford potential competitors against renal insult induced by polyvalent anion pollutants in experimentally studied animals model. As a route for novel drug discovery, further investigation should be attempted to optimize their augmenting reno-protecting potential.

Effect of branched-chain amino acids in patients receiving intervention for hepatocellular carcinoma

AIM: To investigate the usefulness of branched-chain amino acids (BCAA) before transarterial chemoembolization (TACE) or radiofrequency ablation (RFA).

Herbicide-Resistant Mutations in Acetolactate Synthase Can Reduce Feedback Inhibition and Lead to Accumulation of Branched-Chain Amino Acids

The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids that are critical for animal growth and development. Animals need to obtain BCAAs from their diet because they cannot synthesize them. Plants are the ultimate source of these amino acids. Acetolactate synthase (ALS) is the first common enzyme in the biosynthesis of BCAAs. The metabolic control of BCAA biosynthesis involves allosteric regulation of ALS by the end-products of the pathway, i.e., valine, leucine and isoleucine. ALS holoenzyme seems to consist of two large catalytic subunits and two small regulatory subunits. In a previous study, using homologous recombination dependent gene targeting we created rice plants in which W548Land S627I mutations were induced into the endogenous gene encoding the ALS catalytic subunit. These two amino acid substitutions conferred hypertolerance to the ALS-inhibiting herbicide bispyripac-sodium. In this study, we revealed that feedback regulation by valine and leucine was reduced by these two amino acid substitutions. Furthermore, in leaves and seeds of ALS mutants with W548Land/or S627I substitution, a 2- to 3-fold increase in BCAAs was detected. Our results suggest that the ALS catalytic subunit is also involved in feedback regulation of ALS, and that judicious modification of the regulatory and catalytic subunits of ALS-coding genes by gene targeting can lead to the efficient accumulation of BCAA in plants.

OPTICALLY ACTIVE AMINO ACIDS WITH HIGHLY BRANCHED SIDE CHAIN (I) SYNTHESIS OF D- AND L- 2-AMINO-5,5-DIMETHYLHEXANOIC ACID AND 2-AMINO-6,6-DIMETHYLHEPTANOIC ACID

The title compounds were prepared by the enzymatic resolution of the corresponding N-acetylated DL-amino acids methyl esters, which were obtained from t-butyl chloride via an 8-step synthesis.

Functional microbiomics reveals branched-chain amino acids depletion for alleviation of insulin resistance by berberine

Increased circulating branched-chain amino acids(BCAAs)have been involved in the pathogenesis of obesity and insulin resistance.However,evidence relating berberine(BBR),gut microbiota,BCAAs,and insulin resis⁃tance is limited.Here,we showed that BBR could effectively rectify steatohepatitis and glucose intolerance in high-fat diet(HFD)-fed mice.BBR reorganized gut microbiota populations under both the normal chow diet(NCD)and HFD.Particu⁃larly,BBR noticeably decreased the relative abundance of BCAA-producing bacteria,including order Clostridiales;fami⁃lies Streptococcaceae,Clostridiaceae,and Prevotellaceae;and genera Streptococcus and Prevotella.Compared with the HFD group,predictive metagenomics indicated a reduction in the proportion of gut microbiota genes involved in BCAA biosynthesis but the enrichment genes for BCAA degradation and transport by BBR treatment.Accordingly,the elevated serum BCAAs of HFD group were significantly decreased by BBR.Furthermore,the Western blotting results implied that BBR could promote the BCAA catabolism in the liver and epididymal white adipose tissues of HFD-fed mice by acti⁃vation of the multienzyme branched-chain α-ketoacid dehydrogenase complex,whereas by inhibition of the phosphoryla⁃tion state of BCKDHA(E1α subunit)and branched-chain α-ketoacid dehydrogenase kinase.The ex vivo assay further confirmed that BBR could increase BCAA catabolism in both AML12 hepatocytes and 3T3-L1 adipocytes.Finally,data from healthy subjects and diabetics confirmed that BBR could improve glycemic control and modulate circulating BCAAs.Besides,functional microbiomics integrated high-throughput microbial genomics,metabolomics and molecular biotechnology has also been successfully applied to reveal the anti-obesity mechanism of hydroxysafflor yellow A.

Plasma Levels of Amino Acids in Japanese Men and Their Changes after the Administration of Glucose and Sucrose

Background: It is not known whether plasma amino acids levels are different between young and old men in Japan. No research has been reported about changes in plasma levels of amino acids after the administration of glucose or sucrose to young and aged men. Objective: We want to know whether there are age differences in plasma levels of amino acids and if the administration of glucose or sucrose influences their levels. Results: Old people had lower plasma levels of most of amino acids, especially essential and branched-chain amino acids than young men. Plasma levels of amino acids were measured after the administration of 50 grams of glucose or sucrose to young (18 - 22 years old) and aged (≥50 years old) male adults. Plasma levels of total amino acids decreased after the administration of glucose. Decrease in the total amino acid levels was significant in aged men after the administration of sucrose. A significant decrease in plasma levels of total non-essential amino acids was observed at 120 min after the administration of glucose but not sucrose in both aged and young men. Both glucose and sucrose administrations resulted in a significant decrease in the plasma levels of the total essential amino acid levels and branched amino acids in young and aged men. Conclusion: These results suggest that there are age differences in plasma levels of amino acids. Upon the administration of glucose or sucrose amino acids, particularly essential amino acids, decreased in plasma. These amino acids may be transported from the blood soon after the administration of sugar (glucose or sucrose) to the tissues, such as muscles, possibly due to an increase in the insulin levels.

支链氨基酸转氨酶1在食管鳞癌中的表达及其临床意义

目的探讨食管鳞癌(ESCC)患者癌组织中支链氨基酸转氨酶1(BCAT1)的表达及临床意义。方法采用qRT-PCR和Western blot技术检测食管鳞癌细胞系中BCAT1基因的表达水平,筛选出合适的食管癌细胞,作为后续研究。敲低和过表达BCAT1,采用Western blot检测ESCC细胞中BCAT1的蛋白表达水平。CCK-8活力测定、克隆形成实验、划痕实验、Transwell检测ESCC细胞增殖、迁移和侵袭等细胞表型的变化。结果qRT-PCR和Western blot结果显示,与正常细胞相比,BCAT1在ESCC中的相对表达量降低,尤其是KYSE150和Eca109细胞更为明显,因此选择这两株细胞进行研究。CCK-8细胞增殖实验结果显示,细胞在转染BCAT1 siRNA 48 h后,其增殖率明显高于对照组;而过表达BCAT1之后,效果则相反。克隆形成实验结果表明,BCAT1的敲低显著促进ESCC细胞的克隆形成,而BCAT1的过表达显著抑制ESCC细胞的克隆形成。细胞划痕实验和Transwell实验结果表明,与Control siRNA组相比,BCAT1 siRNA组ESCC细胞的迁移和侵袭明显升高;而过表达组中ESCC细胞的迁移和侵袭明显受到抑制。结论BCAT1在ESCC中低表达,BCAT1低表达显著促进ESCC细胞增殖、迁移和侵袭。

BCAT1抑制剂BAY-069的合成工艺优化

BAY-069是目前体外活性最强的支链氨基酸转氨酶1(BCAT1)抑制剂,但其报道的合成路线存在原料成本较高、总收率极低和中间体结构表征不充分等缺点。本研究基于已有合成路线,重点对其合成工艺中的Ullmann偶联反应进行了系统优化。以1-硝基萘(1)为起始原料,经过7步反应和手性色谱柱手性拆分合成目标化合物BAY-069。所有中间体和目标化合物均经1 H NMR,13 C NMR和HR-MS表征。以Ullmann偶联反应为主要优化步骤的路线,其优化后的总收率为11.0%(3b→(±)-BAY-069),是原总收率1.6%(3a→(±)-BAY-069)的6.9倍。

BCAT1作为胰腺导管腺癌潜在诊断标志物的临床应用价值研究

目的 本研究拟验证前期研究发现的bcat1基因表达产物支链氨基酸转氨酶1(BCAT1)作为胰腺导管腺癌潜在血清学诊断标志物的临床应用价值。方法 收集临床PDAC患者血清样本作为实验组,收集胃癌、肝癌、结直肠癌、慢性胰腺炎患者及健康人群血清样本作为对照,采用酶联免疫吸附实验(ELISA)检测血清样本BCAT1浓度,验证其作为标志物的临床诊断价值。结果 ELISA结果显示PDAC组患者血清BCAT1浓度显著高于健康对照组,差异有统计学意义(P<0.05,U=1 206)。PDAC组患者血清BCAT1浓度高于慢性胰腺炎组,差异有统计学意义(P<0.05,H=33.80);与其他消化道肿瘤相比,高于肝癌组和结直肠癌组,差异有统计学意义(P<0.05,H=33.80),与胃癌组差异无统计学意义(P>0.05,H=33.80)。BCAT1与CA19-9的相关性较好,且差异有统计学意义(P<0.05,R^(2)=0.080 52),与CEA(R^(2)=2.265e-005)、CA125(R^(2)=0.025 88)和CA72-4(R^(2)=0.007 7)相关性较低,差异无统计学意义(P>0.05);BCAT1诊断PDAC的AUC优于CA72-4,与CA125和CEA相当,劣于CA19-9;BCAT1 cut off值为1.556ng/mL,敏感度为64.1%,特异度为80%。BCAT1在PDAC早中期患者血清浓度中位数为0.283 ng/mL,晚期患者升高为0.482 ng/mL,差异有统计学意义(P<0.05,U=1029);在肿瘤≥40 mm(U=641)、中低分化(U=435)、胰头部位(H=2.767)均表现为表达水平升高,差异无统计学意义(P均>0.05)。动态观测的BCAT1浓度在第0天和1~30天(U=44)、31~60天和61~90天(U=36)浓度差异有统计学意义(P均<0.05)。结论 BCAT1作为潜在的血清学标志物,对于PDAC的鉴别诊断、肿瘤分期、疾病进展判断具有参考价值,是目前现有的PDAC血清标志物的有益补充。

补喂支链氨基酸对速步马1km速步赛成绩及赛前、赛后血浆生化指标的影响

本试验旨在通过研究补喂支链氨基酸对速步马1 km速步赛成绩及赛前、赛后血浆抗氧化指标以及激素、肌酸、葡萄糖、乳酸、肌酐含量的影响,为支链氨基酸在速步马训练、比赛中的应用提供参考数据。试验选取年龄相近(4岁左右)、体重相近[(457±50)kg]并经过严格训练的伊犁马公马8匹(速步赛用马),随机分为2组,分别为对照组、试验组,每组4匹。每天每匹马分别饲喂3 kg颗粒精料,苜蓿干草自由采食,在此基础上试验组每天每匹马补喂72 g支链氨基酸(由35.0 g亮氨酸、16.6 g异亮氨基酸、20.4 g缬氨酸组成),进行为期38 d(预试期7 d,正试期31 d)的补饲试验及训练试验。结果表明:补喂支链氨基酸可提高速步马的比赛成绩,同时显著提高速步马赛后30 min血浆总抗氧化能力及赛后24 h血浆超氧化物歧化酶活力(P<0.05),但对血浆中激素、肌酸、葡萄糖、乳酸、肌酐含量无显著影响(P>0.05)。由此得出,补喂支链氨基酸可缩短速步马比赛用时,提高速步马机体的抗氧化能力,但对血浆中激素、葡萄糖、肌酸、乳酸、肌酐含量无显著影响。

支链氨基酸转氨酶1在上皮性卵巢癌中的表达及临床意义

目的:探讨上皮性卵巢癌(epithelial ovarian cancer,EOC)患者癌组织中支链氨基酸转氨酶1(branched-chain amino-acid transaminase 1,BCAT1)的表达及临床意义。方法:采用免疫组织化学法检测133例EOC癌组织中BCAT1表达情况,根据免疫组织化学评分分为BCAT1高表达组(n=41)及低表达组(n=92),卡方检验分析BCAT1的表达与临床病理因素间的关系,Kaplan-Meier生存曲线和对数秩检验比较BCAT1高、低表达组患者无瘤生存率及总生存率的差异,Cox比例风险模型分析影响EOC患者预后的因素。结果:BCAT1表达与宫颈癌国际妇产科联盟(Federation International of Gynecology and Obstetrics, FIGO)分期(P=0.004)、淋巴结转移(P=0.001)显著相关,与糖类抗原125(CA125)水平(P=0.538)、组织学类型(P=0.306)、年龄(P=0.524)、肿瘤大小(P=0.632)、腹水(P=0.178)无显著相关性(P>0.05)。BCAT1高表达组患者1年、3年无瘤生存率及总生存率显著低于BCAT1低表达组(P<0.001)。单因素分析示CA125(P<0.001)、肿瘤大小(P=0.003)、组织学类型(P=0.004)、淋巴结转移(P<0.001)、FIGO分期(P<0.001)和BCAT1表达(P<0.001)是影响EOC患者无瘤生存率的危险因素。多因素分析示FIGO分期(P<0.001)和BCAT1表达(P=0.013)是影响EOC患者无瘤生存率的独立危险因素。单因素分析示FIGO分期(P=0.022)、BCAT1表达(P=0.004)及淋巴结转移(P=0.046)是影响EOC患者总生存率的危险因素;多因素分析示FIGO分期(P<0.001)和BCAT1表达(P=0.025)是影响EOC患者总生存率的独立危险因素。结论:EOC癌组织中BACT1高表达,且与FIGO分期、淋巴结转移和预后显著相关,是影响EOC患者预后的分子标志物。

BCAT1促进肿瘤发生发展的研究进展

支链氨基酸转移酶1(branched-chain amino acid transaminase 1,BCAT1)是催化支链氨基酸代谢的关键酶.国内外研究已证实BCAT1在多种恶性肿瘤中呈现高表达,并提示与肿瘤细胞增殖、转移及侵袭密切相关.本文拟就BCAT1的理化性质、生物学功能及其与肿瘤发生、发展的相关研究进行简要综述,为进一步研究BCAT1与恶性肿瘤的关系提供线索.

华蟾素通过支链氨基酸氨基转移酶1调控直肠癌细胞增殖的机制研究

目的探究华蟾素通过支链氨基酸氨基转移酶1 (branched-chain amino acid transferase-1,BCAT1)调控直肠癌细胞增殖的机制。方法 SW480细胞分为四组:正常对照组、低浓度华蟾素组(22.5μg/L)、中浓度华蟾素组(45μg/L)、高浓度华蟾素组(90μg/L),分别处理12 h、24 h、48 h。QPCR、蛋白质免疫印迹法(Western blot)检测SW480细胞中BCAT1表达水平。采用siRNA沉默BCAT1后,观察SW480细胞的生长状态和凋亡率。各组细胞处理后,CCK-8检测华蟾素对细胞的增殖影响;Q-PCR检测各组细胞BCAT1 mRNA表达水平;Western blot检测各组细胞BCAT1蛋白表达水平。JC-1检测各组细胞线粒体膜电位。结果 Western blot和Q-PCR结果显示SW480细胞中BCAT1高表达。不同浓度华蟾素作用直肠癌细胞后,低浓度华蟾素处理后就可以抑制SW480细胞的增殖,且在不同时间点,华蟾素能够以浓度依赖的方式显著抑制SW480细胞的活力,差异有统计学意义(P<0.05)。分别采用不同浓度华蟾素处理SW480细胞48 h后,检测各组细胞线粒体膜电位,结果显示,低浓度的华蟾素处理后,SW480细胞的线粒体膜电位降低,且随着华蟾素浓度的增高,线粒体膜电位下降显著,差异有统计学意义(P<0.05)。Q-PCR检测各组细胞BCAT1 mRNA的表达量,Western blot检测其蛋白表达量,结果显示,与正常对照组细胞相比,低浓度的华蟾素处理48 h后,BCAT1mRNA、蛋白的表达量出现明显下降,且随着华蟾素浓度的升高,BCAT1 mRNA。蛋白的表达量下降更为明显,呈浓度依赖,差异有统计学意义(P<0.05)。沉默BCAT1后,细胞较正常的SW480细胞增殖率降低,且差异有统计学意义(P<0.05)。结论华蟾素可以通过抑制BCAT1的活性来抑制直肠癌细胞的增殖。

杂合子亲属活体肝移植治疗儿童BCKDHB基因新复合突变枫糖尿病1例并文献复习

目的总结枫糖尿病的杂合子亲属活体肝移植治疗效果。方法1例男性3岁患儿,因发现枫糖尿病半年于2017年7月5日入院。患儿空腹状态出现阵发性口齿不清、下肢运动功能障碍半年,枫糖样体味明显,语言发育稍迟缓,无其他生长发育异常和智力缺陷。血清支链氨基酸(BCAA)检查示亮氨酸684μmol/L,缬氨酸559μmol/L,经基因检测结合BCAA检查诊断为枫糖尿病Ⅰb型。行亲属活体肝移植,供者为患儿父亲。术后常规应用免疫抑制、抗病毒、抗感染方案及维持水、电解质、酸碱平衡等必要营养支持。他克莫司剂量根据生化指标和受者细胞色素P450(CYP)3A5基因型进行调整。糖皮质激素于术后6个月左右停用。结果受者肝功能于术后1个月恢复至正常范围,术后3年基本趋于稳定。受者氨基酸水平术后即降至正常,术后正常饮食1个月BCAA继续降低。截止至投稿日,受者生长发育良好,情况稳定,生活质量高。结论突变杂合子亲属活体肝移植治疗枫糖尿病安全有效,降低了突发急性代谢事件的可能性,极大地改善了受者的生活质量,为枫糖尿病的外科治疗提供了新思路。

1H nuclear magnetic resonance spectroscopy-basedmetabonomic study in patients with cirrhosis and hepaticencephalopathy

AIM: To identify plasma metabolites used as biomarkers in order to distinguish cirrhotics from controls and encephalopathics.METHODS: A clinical study involving stable cirrhotic patients with and without overt hepatic encephalopathy was designed. A control group of healthy volunteers was used. Plasma from those patients was analysed using 1H- nuclear magnetic resonance spectroscopy. We used the Carr Purcell Meiboom Gill sequence to process the sample spectra at ambient probe temperature. We used a gated secondary irradiation field for water signal suppression. Samples were calibrated and referenced using the sodium trimethyl silyl propionate peak at 0.00 ppm. For each sample 128 transients(FID's) were acquired into 32 K complex data points over a spectral width of 6 KHz. 30 degree pulses were applied with an acquisition time of 4.0 s in order to achieve better resolution, followed by a recovery delay of 12 s, to allow for complete relaxation and recovery of the magnetisation. A metabolic profile was created for stable cirrhotic patients without signs of overt hepatic encephalopathy and encephalopathic patients as well as healthy controls. Stepwise discriminant analysis was then used and discriminant factors were created to differentiate between the three groups.RESULTS: Eighteen stabled cirrhotic patients, eighteen patients with overt hepatic encephalopathy and seventeen healthy volunteers were recruited. Patients with cirrhosis had significantly impaired ketone body metabolism, urea synthesis and gluconeogenesis. This was demonstrated by higher concentrations of acetoacetate(0.23 ± 0.02 vs 0.05 ± 0.00, P < 0.01), and b-hydroxybutarate(0.58 ± 0.14 vs 0.08 ± 0.00, P < 0.01), lower concentrations of glutamine(0.44 ± 0.08 vs 0.63 ± 0.03, P < 0.05), histidine(0.16 ± 0.01 vs 0.36 ± 0.04, P < 0.01) and arginine(0.08 ± 0.01 vs 0.14 ± 0.02, P < 0.03) and higher concentrations of glutamate(1.36 ± 0.25 vs 0.58 ± 0.04, P < 0.01), lactate(1.53 ± 0.11 vs 0.42 ± 0.05, P < 0.01), pyruvate(0.11 ± 0.02 vs 0.03 ± 0.00, P < 0.01) threonine(0.39 ± 0.02 vs 0.08 ± 0.01, P < 0.01) and aspartate(0.37 ± 0.03 vs 0.03 ± 0.01). A five metabolite signature by stepwise discriminant analysis could separate between controls and cirrhotic patients with an accuracy of 98%. In patients with encephalopathy we observed further derangement of ketone body metabolism, impaired production of glycerol and myoinositol, reversal of Fischer's ratio and impaired glutamine production as demonstrated by lower b-hydroxybutyrate(0.58 ± 0.14 vs 0.16 ± 0.02, P < 0.0002), higher acetoacetate(0.23 ± 0.02 vs 0.41 ± 0.16, P < 0.05), leucine(0.33 ± 0.02 vs 0.49 ± 0.05, P < 0.005) and isoleucine(0.12 ± 0.02 vs 0.27 ± 0.02, P < 0.0004) and lower glutamine(0.44 ± 0.08 vs 0.36 ± 0.04, P < 0.013), glycerol(0.53 ± 0.03 vs 0.19 ± 0.02, P < 0.000) and myoinositol(0.36 ± 0.04 vs 0.18 ± 0.02, P < 0.010) concentrations. A four metabolite signature by stepwise discriminant analysis could separate between encephalopathic and cirrhotic patients with an accuracy of 87%.CONCLUSION: Patients with cirrhosis and patients with hepatic encephalopathy exhibit distinct metabolic abnormalities and the use of metabonomics can select biomarkers for these diseases.

Enhancement of precursor amino acid supplies for improving bacitracin production by activation of branched chain amino acid transporter BrnQ and deletion of its regulator gene lrp in Bacillus licheniformis

Bacitracin,a new type of cyclic peptide antibiotic,is widely used as the feed additive in feed industry.Branched chain amino acids(BCAAs)are the key precursors for bacitracin synthesis.In this research,soybean meal was served as the raw material to supply precursor amino acids for bacitracin synthesis,and enhanced production of bacitracin was attempted by engineering BCAA transporter BrnQ and its regulator Lrp in the bacitracin industrial production strain Bacillus licheniformis DW2.Firstly,our results confirmed that Lrp negatively affected bacitracin synthesis in DW2,and deletion of lrp improved intracellular BCAA accumulations,as well as the expression level of BCAA transporter BrnQ,which further led to a 14.71%increase of bacitracin yield,compared with that of DW2.On the contrary,overexpression of Lrp decreased bacitracin yield by 12.28%.Secondly,it was suggested that BrnQ acted as a BCAA importer in DW2,and overexpression of BrnQ enhanced the intracellular BCAA accumulations and 10.43%of bacitracin yield.While,the bacitracin yield decreased by 18.27%in the brnQ deletion strain DW2△brnQ.Finally,BrnQ was further overexpressed in lrp deletion strain DW2△lrp,and bacitracin yield produced by the final strain DW2△lrp::BrnQ was 965.34 U/mL,increased by 22.42%compared with that of DW2(788.48 U/mL).Collectively,this research confirmed that Lrp affected bacitracin synthesis via regulating the expression of BCAA transporter BrnQ and BCAA distributions,and provided a promising strain for industrial production of bacitracin.

支链氨基酸转氨酶1基因沉默对缺血脑损伤大鼠的保护作用

目的:探讨支链氨基酸转氨酶1(BCAT1)基因沉默对大鼠缺血性脑损伤的保护作用。方法:选取40只成年雄性SD大鼠随机分为假手术组(sham)、MCAO模型组(MCAO)、MCAO+空白质粒脑室注射组(NC-shRNA)、MCAO+BCAT1干扰质粒脑室注射组(BCAT1-shRNA),利用大脑中动脉栓塞法(MCAO)制备脑缺血模型,通过神经功能缺损评分判断大鼠神经功能损伤情况;real time RT-PCR检测大鼠脑缺血部位BCAT1 mRNA的表达水平;利用商品化试剂盒测定缺血脑组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量;TUNEL染色检测缺血脑组织细胞凋亡情况。结果:MCAO组大鼠神经功能缺损评分升高(P<0.05),BCAT1 mRNA表达水平升高(P<0.05),脑组织梗死灶增大,SOD活性降低(P<0.05),MDA水平升高(P<0.05),TUNEL染色阳性细胞数量增多(P<0.05)。而BCAT1基因沉默可降低缺血性脑损伤后大鼠神经功能缺损评分(P<0.05),降低BCAT1 mRNA表达水平(P<0.05),缩小脑组织梗死灶范围,上调SOD活性(P<0.05),下调MDA含量(P<0.05),减少细胞凋亡(P<0.05)。结论:大鼠脑缺血可导致BCAT1表达上调,BCAT1基因沉默具有一定神经保护作用。