高同型半胱氨酸诱导血管内皮功能障碍促进微循环障碍和微血栓形成

目的：采用蛋氨酸灌胃复制高同型半胱氨酸血症(hyperhomocysteinemia,HHcy)致内皮功能障碍,在此基础上，联合脂多糖（lipopolysaccharide，LPS）和角叉菜胶（carrageenan，Ca）造成大鼠体内广泛微血栓形成，观察血管内皮损伤和功能障碍对大鼠体内微血栓形成的促进作用。方法: ①内皮损伤模型的建立。SD大鼠随机分为对照组（control）、内皮功能障碍组（HHcy）。HHcy组采用蛋氨酸灌胃4周复制HHcy致内皮功能障碍模型，对照组以等量纯净水灌胃。4 周后检测血浆同型半胱氨酸（homocysteine，Hcy）水平，并取大鼠胸主动脉段进行血管舒张功能检测，同时检测血浆一氧化氮（NO）和血管性假血友病因子（von Willebrand factor，vWF）水平，以评价血管内皮功能状况。②Ca/LPS诱导微血栓形成。SD大鼠随机分为对照组（control）、微血栓组（Ca/LPS）、内皮功能障碍加微血栓组（HHcy＋Ca/LPS）。Ca/LPS组大鼠腹腔注射Ca，16 h再腹腔注射LPS。注射LPS 20 h后心脏采血检测凝血功能和血小板计数，镜下观测肠系膜微循环，24 h大鼠颈动脉采血结束实验，检测血浆NO和vWF值。对照组腹腔注射等量生理盐水，检测指标同模型组。HHcy＋Ca/LPS组大鼠经蛋氨酸灌胃持续4周后，再按照上述方法注射Ca/LPS，观察内皮功能障碍对大鼠微循环障碍和微血栓形成的影响。结果： ①蛋氨酸灌胃4周导致HHcy,血浆vWF水平显著升高，NO水平降低，内皮依赖性血管舒张功能显著降低，提示血管内皮功能受损，大鼠内皮功能障碍模型复制成功。②Ca/LPS组肠系膜微循环可见广泛微血栓形成，注射LPS后20 h ，通过检测凝血指标可见血液处于高凝状态。而与之比较，HHcy＋Ca/LPS组微循环障碍进一步加强，血小板计数减少，血浆NO值降低，vWF升高；注射LPS 20 h后可见血液处于继高凝状态之后的消耗性低凝状态。结论： 蛋氨酸灌胃4周导致HHcy,诱导血管内皮功能障碍。联合Ca/ LPS 造模可建立微循环障碍和微血栓形成的动物模型，而内皮功能障碍能加速加重微循环障碍和微血栓形成。     

广东汉族人蛋氨酸合成酶基因多态性

目的了解广东汉族人蛋氨酸合成酶基因的分布特点.方法应用聚合酶链反应技术对211例正常人蛋氨酸合成酶基因进行扩增,进行图谱分析.并结合文献进行了不同种族间的分析比较.结果广东汉族人群中MS基因型以AA最多见,AG次之.AA基因型频率为0.8009、AG为0.1802、GG为0.0189.A基因型频率为0.8910、G为0.1090.与其他种族相比较,MS基因型在中国正常人群中的分布与白种人群中的分布差异显著.结论蛋氨酸合成酶基因因多态性在不同种族间分布存在着明显的差异.     

蛋脑啡肽对猴免疫缺陷病毒感染CEM×174细胞kappa阿片受体表达的调节作用(英文)

目的：研究蛋脑啡肽对猴免疫缺陷病毒（ＳＩＶ）感染ＣＥＭ×１７４ 细胞ｋａｐｐａ 阿片受体表达的调节作用。方法：用ＳＩＶ 感染ＣＥＭ×１７４ 细胞并加入不同浓度蛋脑啡肽。在２４ ｈ 提取ＲＮＡ,用ＲＴ－ＰＣＲ 方法扩增ｋａｐｐａ 阿片受体ｍ ＲＮＡ 并且进行定量分析。结果：显示ＳＩＶ 能够抑制ＣＥＭ×１７４ 细胞的生长。在１０－ ７ｍ ｏｌ／Ｌ蛋脑啡肽存在下,ＳＩＶ 对细胞的损害减轻。１０－ ７ｍ ｏｌ／Ｌ和１０－ ６ｍ ｏｌ／Ｌ蛋脑啡肽不能改变正常细胞ｋａｐｐａ 阿片受体的表达,但是在ＳＩＶ 感染组的表达显著增高。结论：实验结果提示蛋脑啡肽能够维持正常淋巴细胞的生长。Ｋａｐｐａ 阿片受体表达的改变可能与蛋脑啡肽对免疫细胞的调节机理有关     

蛋氨酸合成酶还原酶基因A66G多态性与Down综合征发生的相关研究

目的:研究蛋氨酸合成酶还原酶(MTRR)基因A66G多态性与Down综合征的关系。方法:采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)法对32例DS患儿母亲及70例未生育DS患儿女性MTRR的A66G进行基因分析。比较上述各组基因型和等位基因频率分布有无差异。结果:MTRR基因A66G突变型等位基因G频率在实验组和对照组中有显著性差异,GG基因型频率分布差异有显著性(P<0·05)。AG基因型比AA基因型生育DS患儿风险高1·98倍,GG基因型比AA基因型生育DS患儿风险高5·2倍。结论:MTRR A66G基因多态性与Down综合征发生相关,AG、GG基因型增加了Down综合征的发生风险。     

Cutting back on the essentials: Can manipulating intake of specific amino acids modulate health and lifespan?

With few exceptions, nutritional and dietary interventions generally impact upon both old-age quality of life and longevity. The life prolonging effects, commonly observed with dietary restriction reportedly are linked to alterations in protein intake and specifically limiting the dietary intake of certain essential amino acids. There is however a paucity of data methodically evaluating the various essential amino acids on health- and lifespan and the mechanisms involved. Rodent diets containing either lower methionine content, or tryptophan, than that found in commercially available chow, appear to elicit beneficial effects. It is unclear whether all of these favorable effects associated with restricted intake of methionine and tryptophan are due to their specific unique properties or if restriction of other essential amino acids, or proteins in general, may produce similar results. Considerably more work remains to be done to elucidate the mechanisms by which limiting these vital molecules may delay the onset of age-associated diseases and improve quality of life at older ages.     

Polymorphisms in <Emphasis Type="Italic">methionine synthase</Emphasis> (A2756G) and <Emphasis Type="Italic">cystathionine β-synthase</Emphasis> (844ins68) and susceptibility to carcinomas of the upper gastrointestinal tract

Purpose

Folate deficiency is considered to increase the risk for the development of malignant tumors such as prostate and colorectal cancer. Methionine synthase (MTR) and cystathionine ß-synthase (CBS) are enzymes that play a central role in folate metabolism, thereby affecting DNA methylation and synthesis. A single A→G substitution at nucleotide 2756 of the MTR and a 68 bp CBS insertion polymorphism in exon 8 have been associated with decreased enzyme activity. The purpose of this study is to compare the association of the MTR A2756G polymorphism and CBS insertion polymorphism with susceptibility to carcinomas of the upper gastrointestinal tract.

Methods

Using the restriction fragment length polymorphism (RFLP)-PCR, the prevalence of MTR A2756G and CBS insertion polymorphism was determined in healthy controls (n = 257) and in patients with esophageal squamous cell carcinoma (ESCC) (n = 263), Barrett’s esophagus-associated esophageal adenocarcinoma (BC) (n = 89), cardiac carcinoma (CC) (n = 144), or gastric carcinoma (GC) (n = 221) from German Caucasian subjects.

Results

No significant difference in MTR A2756G genotype distribution was observed between controls (A/A 66.9%, A/G 29.8%, G/G 3.3%) and patients with ESCC (A/A 61.7%, A/G 36.3%, G/G 2.1%), BC (A/A 69.2%, A/G 26.9%, G/G 3.9%), CC (A/A 51.8%, A/G 44.6%, G/G 3.6%), or GC (A/A 73.4%, A/G 20.9%, G/G 5.7%). Similarly, the CBS genotype (I: allele with 68 bp insertion; N: allele without insertion) distribution among German patients with ESCC (N/N 86.8%, I/N 13.2%), BC (N/N 90.2%, I/N 9.8%), CC (N/N 90.1%, I/N 9.9%) or GC (N/N 91.3%, I/N 8.7%) was not different from healthy controls (N/N 90.4%, I/N 9.6%). The gene allele constellation I/I was not present.

Conclusions

The current study suggests that there is no association between MTR A2756G polymorphism and the CBS (844ins68) insertion polymorphism and cancer of the upper gastrointestinal tract.

     

过量服用蛋氨酸所致高同型半胱氨酸血症对缺血性血管新生的抑制作用

高同型半胱氨酸血症是引起动脉粥样硬化的一种独立危险因素。过量服用蛋氨酸会导致血清中同型半胱氨酸浓度增高、内皮功能受损、血管舒缩功能减弱。本研究使用过量服用蛋氨酸导致高同型半胱氨酸血症大鼠，与对照组比较，观察缺血下肢血管新生的情况，判断高同型半胱氨酸血症对缺血性血管新生的影响。将36只雄性Sprague-Dawley大鼠分为两组：对照组和高同型半胱氨酸血症组。对照组始终给予自来水；高同型半胱氨酸血症组则给予含有0．5％蛋氨酸的饮水。两组动物分别按上述方法给予不同饮水2周后，手术切除左侧股动、静脉，观察缺血28d内缺血区域血管新生和侧枝血管形成的情况。过量服用蛋氨酸导致的高同型半胱氨酸血症减弱了大鼠下肢慢性缺血性血管新生和侧枝血管的建立，这可能与高同型半胱氨酸血症减弱内皮源性一氧化氮生物活性有关。     

Arachidyl amido cholanoic acid improves liver glucose and lipid homeostasis in nonalcoholic steatohepatitis via AMPK and mTOR regulation

BACKGROUND Arachidyl amido cholanoic acid(Aramchol) is a potent downregulator of hepatic stearoyl-CoA desaturase 1(SCD1) protein expression that reduces liver triglycerides and fibrosis in animal models of steatohepatitis. In a phase IIb clinical trial in patients with nonalcoholic steatohepatitis(NASH), 52 wk of treatment with Aramchol reduced blood levels of glycated hemoglobin A1c, an indicator of glycemic control.AIM To assess lipid and glucose metabolism in mouse hepatocytes and in a NASH mouse model [induced with a 0.1% methionine and choline deficient diet(0.1 MCD)] after treatment with Aramchol.METHODS Isolated primary mouse hepatocytes were incubated with 20 μmol/L Aramchol or vehicle for 48 h. Subsequently, analyses were performed including Western blot, proteomics by mass spectrometry, and fluxomic analysis with ~(13)C-uniformly labeled glucose. For the in vivo part of the study, male C57 BL/6 J mice were randomly fed a control or 0.1 MCD for 4 wk and received 1 or 5 mg/kg/d Aramchol or vehicle by intragastric gavage for the last 2 wk. Liver metabolomics were assessed using ultra-high-performance liquid chromatography-time of flight-MS for the determination of glucose metabolism-related metabolites.RESULTS Combination of proteomics and Western blot analyses showed increased AMPK activity while the activity of nutrient sensor mTORC1 was decreased by Aramchol in hepatocytes. This translated into changes in the content of their downstream targets including proteins involved in fatty acid(FA) synthesis and oxidation [PACCα/β(S79), SCD1, CPT1A/B, HADHA, and HADHB], oxidative phosphorylation(NDUFA9, NDUFB11, NDUFS1, NDUFV1, ETFDH, and UQCRC2), tricarboxylic acid(TCA) cycle(MDH2, SUCLA2, and SUCLG2), and ribosome(P-p70S6K[T389] and P-S6[S235/S236]). Flux experiments with ~(13)C uniformely labeled glucose showed that TCA cycle cataplerosis was reduced by Aramchol in hepatocytes, as indicated by the increase in the number of rounds that malate remained in the TCA cycle. Finally, liver metabolomic analysis showed that glucose homeostasis was improved by Aramchol in 0.1 MCD fed mice in a dose-dependent manner, showing normalization of glucose, G6P, F6P, UDP-glucose, and Rbl5 P/Xyl5 P.CONCLUSION Aramchol exerts its effect on glucose and lipid metabolism in NASH through activation of AMPK and inhibition of mTORC1, which in turn activate FA β-oxidation and oxidative phosphorylation.     

L-甲硫氨酸通过调节脊髓DNA甲基化水平减轻甲醛溶液所致急性炎性痛机制研究

背景　甲硫氨酸能够促进DNA甲基化的发生,DNA甲基化参与疼痛的发生发展和维持。急性炎性痛是临床常见症状,控制不及时会转化成慢性炎性痛,外源性补充甲硫氨酸可能通过调节DNA甲基化参与调节急性炎性痛,改善患者疼痛症状。目的　本研究采用甲醛溶液诱导急性炎性痛模型大鼠,观察注射L-甲硫氨酸（L-MET）是否会减轻大鼠足底急性炎性痛并探讨其机制,以期为寻找新的疼痛生物标志物和开发理想的镇痛新药提供理论依据。方法　2017年7月-2018年12月,将24只健康成年清洁级雄性Sprague-Dawley（SD）大鼠按照随机数字表法分为A组（0.9%氯化钠溶液+0.9%氯化钠溶液组）、B组（L-MET+0.9%氯化钠溶液组）、C组（0.9%氯化钠溶液+2 g/L甲醛溶液组）、D组（L-MET+2 g/L甲醛溶液组）,每组6只。B组、D组腹腔注射L-MET,2次/d,总量不超过0.18 mg/kg,连续注射3 d;A组、C组注射等量0.9%氯化钠溶液。C组、D组左后足足跖部皮下注射2 g/L甲醛溶液20 μl,制作甲醛溶液所致急性炎性痛模型,大鼠足部肿胀并会出现相应的抬足舔足行为视为模型制作成功;A组、B组注射等量0.9%氯化钠溶液。全程记录给药后60 min大鼠行为学,并记录疼痛次数,每隔3 min为1个观察时段,共分20个观察时段。行为学检测结束后,将大鼠处死,取脊髓L4~L6之间脊髓组织,检测大鼠脊髓全基因组DNA甲基化水平及大鼠脊髓DNA甲基化转移酶（DNMT）1、DNMT2、DNMT3a、DNMT3b RNA水平。结果　A组、B组大鼠无明显不适异常反应;C组、D组大鼠出现躁动不安、注射足抬起不着地、舔咬或抖动注射足等反应,其疼痛行为反应呈典型的双相变化,从注射后即刻开始,持续3~5 min的急性疼痛时相（第一时相）,5~10 min的静息期,随后出现可持续0~45 min的继发性疼痛时相（第二时相）。C组、D组大鼠各时间点疼痛次数均多于A组、B组（P<0.05）;D组大鼠6~39 min疼痛次数少于C组（P<0.05）。B组、D组大鼠脊髓全基因组DNA甲基化水平高于A组（P<0.05）;C组、D组大鼠脊髓全基因组DNA甲基化水平低于B组（P<0.05）;D组大鼠脊髓全基因组DNA甲基化水平高于C组（P<0.05）。C组、D组大鼠脊髓DNMT3a、DNMT3b RNA水平高于A组、B组（P<0.05）;D组大鼠脊髓DNMT3a RNA水平低于C组,DNMT3b RNA水平高于C组（P<0.05）。结论　L-MET对于甲醛溶液所致急性炎性痛模型大鼠具有明显镇痛作用,其机制与脊髓全基因组DNA甲基化水平以及DNMT水平的变化有关。     

Applications of positron emission tomography in neuro-oncology: A clinical approach

The field of neuro-oncology is concerned with some of the most challenging and difficult to treat conditions in medicine. Despite modern therapies patients diagnosed with primary brain tumours often have a poor prognosis. Imaging can play an important role in evaluating the disease status of such patients. In addition to the structural information derived from MRI and CT scans, positron emission tomography (PET) provides important quantitative metabolic assessment of brain tumours. This review describes the use of PET with radiolabelled glucose and amino acid analogues to aid in the diagnosis of tumours, differentiate between recurrent tumour and radiation necrosis and guide biopsy or treatment. [¹⁸F]Fluorodeoxyglucose (FDG) is the tracer that has been used most widely because it has a 2 h half life and can be transported to imaging centres remote from the cyclotron and radiochemistry facilities which synthesise the tracers. The high uptake of FDG in normal grey matter however limits its use in some low grade tumours which may not be visualised. [¹¹C] methionine (MET) is an amino acid tracer with low accumulation in normal brain which can detect low grade gliomas, but its short 20 min half life has limited its use to imaging sites with their own cyclotron. The emergence of new fluorinated amino acid tracers like [¹⁸F]Fluoroethyl-l-tyrosine (FET) will likely increase the availability and utility of PET for patients with primary brain tumours. PET can, further, characterise brain tumours by investigating other metabolic processes such as DNA synthesis or thymidine kinase activity, phospholipid membrane biosynthesis, hypoxia, receptor binding and oxygen metabolism and blood flow, which will be important in the future assessment of targeted therapy.