基于耐消化肽的核桃主要过敏原Jug r 2的线性表位筛选

由于核桃Jug r 2是核桃中的主要过敏原,Jug r 2的线性表位是引发核桃过敏反应的关键因素,因此筛选Jug r 2线性表位工作是必要的。本研究利用免疫信息学中的DNAStar Protean系统和ABCpred在线工具预测Jug r 2中的B细胞线性表位。利用体外模拟胃肠消化和HPLC-MS/MS对抗消化肽段的一级序列进行分析,并对两种免疫信息学工具预测得到的B细胞线性表位和抗消化肽段在Jug r 2模拟三维结构上进行定位分析。结果表明:预测得到8个B细胞线性表位(AA186~199、AA226~230、AA257~263、AA284~289、AA373~382、AA389~398、AA408~414、AA472~487)和11个抗消化肽段(AA215~220、AA250~260、AA323~337、AA351~356、AA363~388、AA428~438、AA470~483、AA488~513、AA514~526、AA527~541、AA545~572)。在抗消化肽段中,4条与预测或已知真实的B细胞线性表位序列重合,8条与已知真实的T细胞表位序列重合,并且抗消化肽段在Jug r 2三维结构的定位中表现出亲水性和柔韧性的良好抗原性质。综上,研究食物过敏原的耐消化特性可能是研究Jug r 2的线性表位的一个潜在策略。

燕麦耐消化肽纳米载体的制备表征及其对咖啡酸苯乙酯的包埋作用研究

为提高燕麦蛋白的水溶性并提高其在纳米材料领域的应用价值,通过酶水解法制备了燕麦耐消化肽纳米颗粒,并评估其包封疏水活性物质的能力及耐消化特性。燕麦蛋白经胃蛋白酶和胰蛋白酶消化制备出燕麦肽纳米颗粒,为50 nm的球形胶束。燕麦蛋白经过胃蛋白酶消化水解度为3.1%,胰蛋白酶消化水解度为10.7%。对内部相互作用进行分析表明,燕麦肽纳米颗粒主要由疏水作用驱动自组装,氢键和二硫键对维持结构稳定有一定作用。表面活性研究表明,燕麦肽纳米颗粒表面具有一定的疏水性和亲油性,水解改性大大增强了纳米颗粒的水溶性。以咖啡酸苯乙酯为模型药物评估燕麦肽纳米颗粒的载药性能,包封率为71%,载药量为3.5%,咖啡酸苯乙酯在水中的质量浓度从1.8提升至140μg/mL。载药纳米颗粒体外模拟消化结果表明,耐消化肽纳米颗粒具有较强的耐消化特性,在胃肠液中咖啡酸苯乙酯的释放率低。稳态荧光光谱分析表明,疏水相互作用是咖啡酸苯乙酯与肽分子结合的主要作用力。研究表明,燕麦肽纳米颗粒是增加疏水物质溶解度的良好载体。

奥曲肽联合奥美拉唑治疗上消化道出血的疗效观察

目的:探讨奥曲肽联合奥美拉唑治疗上消化道出血的临床疗效。方法:收治上消化道出血患者88例,随机分成对照组和观察组,每组44例。对照组应用奥曲肽0.1mg,加入生理盐水20ml中缓慢静脉推注。观察组在对照组的基础上25mg/小时静滴维持,奥美拉唑40mg加入生理盐水100ml中静滴,2次/日,疗程3天。结果:观察组总有效率为95.5%,对照组为63.6%,两组比较差异有显著性(P<0.05)。结论:奥美拉唑和奥曲肽联合治疗上消化道出血疗效显著,值得推广。

豆腐蛋白体外消化物抑制胶束转运胆固醇作用分析

大豆蛋白肽具有显著的降血脂功效,但目前研究主要集中在小分子肽段,且对蛋白肽降血脂作用的分子机理探究较少.模拟豆腐蛋白的胃肠道消化,得到豆腐蛋白的体外消化物,按相对分子质量（MR）分为3 个级别：〉10 000、3 000～10 000和〈3 000,利用胆固醇胶束实验（采用两种实验基质及两种检测方法）检测其抑制膳食混合胶粒转运胆固醇的作用.结果表明,在分级的3 种豆腐消化物中,MR〉10 000具有最强的抑制膳食混合胶粒转运胆固醇作用,其胆固醇胶束吸收率为62.40%,小于阳性对照（Val-Ala-Trp-Met-Tyr,其胆固醇胶束吸收率为68.41%）,且MR〉10 000豆腐消化物的抑制胶束转运胆固醇作用随着样品质量浓度增大呈先增强后减弱的趋势.此外,胆固醇胶束实验中采用的两种“膳食混合胶粒”的转运效果及两种检测方法的结果均具有-致性,说明豆腐蛋白消化物具有影响膳食混合胶粒转运和胆固醇吸收的作用.

模拟消化方法在食物过敏原潜在致敏性评价中的应用进展

食物过敏已成为全球范围内日益严重的食品安全问题。对食物过敏原的潜在致敏性进行评价有助于更好地了解食物过敏原自身特性及其对过敏人群免疫系统的影响。模拟消化实验是食物过敏原潜在致敏性评价的有力手段。食物过敏原蛋白的消化稳定性为其潜在致敏性评价结果提供了重要参考依据,但并非所有食物过敏原均具有较强的消化稳定性。食物过敏原的潜在致敏性一方面取决于过敏原蛋白在通过消化道时的消化稳定性,另一方面取决于消化产物中具有免疫刺激能力的过敏原表位的丰度。不同模拟消化方法的应用对食物过敏原的消化结果及潜在致敏性评价结果的真实性和可比性具有重要影响。本文系统地介绍了体内及体外模拟消化方法的优缺点及在食物过敏原潜在致敏性评价中的应用研究进展,并综述了食物过敏原消化稳定性与其潜在致敏性评价结果的关系。以期对食物过敏原致敏性评价体系的进一步完善和发展有所帮助。

花生主要过敏原Ara h 1线性B细胞表位的预测及鉴定

花生过敏由于其高致敏率和致敏严重性而引起了人们的广泛关注。Ara h 1是花生中的主要过敏原,属于Cupin超家族,通过抗原表位识别结合免疫球蛋白E引发花生过敏。本研究采用生物信息学分析花生主要过敏原Cupin超家族Ara h 1线性B细胞表位氨基酸组成,及其与Ara h 1二级、三级结构之间关系,通过质谱分析Ara h 1氨基酸序列中的抗消化肽段,并分析抗消化肽段与预测线性B细胞表位的关系。结果表明,Ara h 1的线性B细胞表位富含亲水性氨基酸和带电氨基酸;其二级结构没有明显的分布规律,具有一定的回转折叠结构;分析Ara h 1三级结构发现,表位主要位于单体之间的疏水相互作用区域,部分表位埋入三聚体构象内部;Ara h 1抗消化序列与表位之间存在部分重叠。综上,质谱检测体外模拟胃肠道消化肽段并结合表位生物信息学分析可以作为鉴定Cupin超家族线性B细胞表位的新方法。

Expression Pattern of Peptide and Amino Acid Genes in Digestive Tract of Transporter Juvenile Turbot(Scophthalmus maximus L.)

Turbot(Scophthalmus maximus L.),a carnivorous fish species with high dietary protein requirement,was chosen to examine the expression pattern of peptide and amino acid transporter genes along its digestive tract which was divided into six segments including stomach,pyloric caeca,rectum,and three equal parts of the remainder of the intestine.The results showed that the expression of two peptide and eleven amino acid transporters genes exhibited distinct patterns.Peptide transporter 1(Pep T1) was rich in proximal intestine while peptide transporter 2(PepT2) was abundant in distal intestine.A number of neutral and cationic amino acid transporters expressed richly in whole intestine including B^0-type amino acid transporter 1(B^0AT1),L-type amino acid transporter 2(LAT2),T-type amino acid transporter 1(TAT1),proton-coupled amino acid transporter 1(PAT1),y^+L-type amino acid transporter 1(y^+LAT1),and cationic amino acid transporter 2(CAT2) while ASC amino acid transporter 2(ASCT2),sodium-coupled neutral amino acid transporter 2(SNAT2),and y^+L-type amino acid transporter 2(y^+LAT2) abundantly expressed in stomach.In addition,system b^(0,+) transporters(rBAT and b^(0,+)AT) existed richly in distal intestine.These findings comprehensively characterized the distribution of solute carrier family proteins,which revealed the relative importance of peptide and amino acid absorption through luminal membrane.Our findings are helpful to understand the mechanism of the utilization of dietary protein in fish with a short digestive tract.

Separation of growth-stimulating peptides for Bifidobacterium from soybean conglycinin

AIM： To isolate and identify the soybean conglycinin peptides that selectively stimulates the growth of bifidobacteria in vitro, and to investigate the effect of soybean conglycinin peptides on intestinal ecosystem in vivo. METHODS： Soybean conglycinin was purified from soybean seeds by gel filtration （Sepharose-CL-6B）. These proteins were submitted to hydrolysis by pepsin. Several growth-stimulating peptides for bifidobacteria were isolated chromatographically from pepsin hydrolysis of soybean conglycinin and identified by means of matrixassisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS）. Parallel to in vitro study, in vivo experiments with soybean conglycinin peptides were performed in mice. Ninety male KM mice were randomly assigned into five groups of 16 mice each, and each group was administered for 21d intragastrically with physiological saline （control）, conglycinin, pepsin-treated conglycinin （PTC）, the most active fraction which isolated from pepsin-treated conglycinin （P2-PTC） and HCl-full hydrolysis of conglycinin （HCl-FHC）, respectively. Intestinal microflora were evaluated by standard microbiologic methods and biochemical assays of cecal content samples after treatment. RESULTS： The results showed that the peptides which were isolated from soybean conglycinin could stimulate the growth of bifidobacteria in vitro, and the molecular mass of purified peptides with MALDI-TOF-MS ranged from 693.32 to 1829.55. Compared with control group, in vivo experiments showed that P2-PTC group decreased cecal pH （7.08±0.08 vs7.21±0.09, P〈0.05） and enterococcicounts （5.38±0.26 log10CFU/g vs 5.78±0.19 log10CFU/g, P〈0.05）, significantly increased sIgA level （172.08±35.40 ng/g vs 118.27±33.93 ng/g, P〈0.01） and β-galactosidase activity （1.28±0.23 U/g vs 1.82±0.58 U/g, P〈0.05） CONCLUSION： The results have shown that conglycinin is good source for enzyme-mediated production of peptides which stimulate the growth of bifidobacteria. These peptides are inactive within the sequence of the parent protein but can be released during enzymatic hydrolysis, and in vivo experiments demonstrate that conglycinin peptides may be beneficial for improving gastrointestinal health.

Presence of CCK-A, B receptors and effect of gastrin and cholecystokinin on growth of pancreatobiliary cancer cell lines

AIM: To investigate the effects of gastrin and cholecystokinin (CCK) and their specific antagonists on the growth of pancreatic and biliary tract cancer cell lines. METHODS: Five pancreatic and 6 biliary cancer cell lines with 2 conrtol cells were used in this study. Cell proliferation study was done using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) test and direct cell count method. Reverse transcription-polymerase chain reaction (RT-PCR) and slot blot hybridization were performed to examine and quantify the expression of hormonal receptors in these cell lines. RESULTS: SNU-308 showed a growth stimulating effect by gastrin-17, as did SNU-478 by both gastrin-17 and CCK-8. The trophic effect of these two hormones was completely blocked by specific antagonists (L-365, 260 for gastrin and L-364, 718 for CCK). Other cell lines did not respond to gastrin or CCK. In RT-PCR, the presence of CCK-A receptor and CCK-B/gastrin receptor mRNA was detected in all biliary and pancreatic cancer cell lines. In slot blot hybridization, compared to the cell lines which did not respond to hormones, those that responded to hormones showed high expression of receptor mRNA. CONCLUSION: Gastrin and CCK exert a trophic action on some of the biliary tract cancers.

Effect of Gastrointestinal Protease Digestion on Bioactivity of Marine Peptides

Focus in nutritional science has turned towards components in, or added to, foods that may possess health beneficial activities beyond the classical nutritional value, namely functional food. Bioactive peptides are examples of such components. In vitro studies on bioactivities have mainly been executed without concerning subsequent digestion after intake and the aim of this work was hence to investigate how the in vitro antioxidative, antihypertensive and caspase activating activities of peptides are affected by digestion with gastrointestinal （GI） proteases. Five different fish protein hydrolysates were chosen to study the effect of in vitro digestion on bioactivity. The protein concentration decreased in all samples during digestion and the molecular weight distribution of the peptides shifted towards lower values. Thus, in vitro digestion with GI proteases resulted in a further degradation of the peptides obtained by hydrolysis. The antihypertensive effect increased in all samples after digestion with GI proteases whereas the antioxidative capacity decreased. The effect on the caspase activity depended on the proteases used in the preparation of hydrolysates. In conclusion, the caspase activity and antihypertensive activity are maintained during digestion with GI proteases, while the antioxidative capacity seems to be reduced.

Mercury (Hg^(2+)) effect on enzyme activities and hepatopancreas histostructures of juvenile Chinese mitten crab Eriocheir sinensis

We studied the effects of mercury (Hg2+) on antioxidant and digestive enzyme activities in terms of LC50 value and on hepatopancreas histostructures of juvenile Chinese mitten crabs Eriocheir sinensis in 40-day exposure to various concentrations of Hg2+ (0, 0.01, 0.05, 0.10, 0.20, and 0.30 mg/L). The results show that the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) significantly increased in the concentrations of 0.01 and 0.05 mg/L, while that of enzyme decreased in 0.10, 0.20 and 0.30 mg/L treatments. Meanwhile, Hg2+ disrupted the histostructures of the hepatopancreas, causing decreases in activities of pepsin, tryptase, amylase, and cellulose, which are synthesized in the hepatopancreas. Moreover, as the Hg2+ concentration increased, the survival rate of the crabs decreased, worst at 56.57% in 0.30 mg/L. Therefore, although crabs are able to tolerate low levels of mercury pollution, high levels lead to cellular injury and tissue damage in hepatopancreas, which then loses some of its vital physiological functions such as absorption, storage, and secretion.

Relationship between metabolic enzyme polymorphism and colorectal cancer

AIM: To clarify the influence of genetic polymorphisms on colorectal cancer. METHODS: The results of 42 related studies from 1990 to 2001 were analyzed by meta-analysis. Mantel-Haenzel fixed-effect model or Dersimonian-Laird random-effect model and ReviewManager 4.1 statistical program were applied in processing the data. RESULTS: Meta analysis of these studies showed that GSTT1 deletion (pooled OR= 1.42), N-acetyltransferase 2 (NAT2)-rapid acetylator phenotype and genotye (pooled OR = 1.08) and NAT2-rapid acetylator phenotype (pooled OR = 1.15) had a significantly increased risk for colorectal cancer (P<0.05), other genotypes like GSTM1 deletion, GSTP1 1le105Val, NAT1*10, NAT2-rapid acetylator genotype CYP1A1 Lle462Val, CYP1A1 MspI*C, MTHFR C677T and MTR A2759G had no significant relationship with colorectal cancer (P>0.05). CONCLUSION: Risks for colorectal cancer are significantly associated with the genetic polymorphisms of GSTT1 deletion, NAT2-rapid acetylator phenotype and genotye and NAT2-rapid acetylator phenotype.

Differences in platelet endothelial cell adhesion molecule-1 expression between peripheral circulation and pancreatic microcirculation in cerulein-induced acute edematous pancreatitis

AIM: To investigate the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1) expression on polymorphonuclear leukocytes (PMNs) in peripheral circulation and pancreatic microcirculation in cerulein-induced acute edematous pancreatitis (AEP).METHODS: Fifty Wistar rats were randomly divided into control group (n=10) and AEP group (n=40). A model of AEP was established by subcutaneous injection of cerulein 5.5 and 7.5 μg/kg at 0 and 1 h after the beginning of experiment respectively. PECAM-1 expression on PMNs from splenic vein and inferior vena cava was determined by RT-PCR at mRNA level and determined by flow cytometry at protein level.RESULTS: In experimental rats, an increased PECAM-1mRNA expression was seen from 4 to 8 h of AEP in peripheral circulation (0.77±0.25%, 0.76±0.28%, 0.89±0.30%,1.00±0.21% ), while in pancreatic microcirculation,expression decreased from 2 h and reached the lowest level at 6 h of AEP (0.78±0.29%, 0.75±0.26%, 0.62±0.28%,0.66±0.20%). There were significant differences at 8-h time point of AEP between peripheral circulation and pancreatic microcirculation (1.00±0.21% vs0.66±0.20%, P＜0.05).Meanwhile,the difference at protein level was also found.CONCLUSION: A reverse expression of PECAM-1 on PMNs was found between peripheral circulation and pancreatic microcirculation, suggesting that inhibition of PECAM-1expression may improve the pathological change of AEP.

Effects of Moxibustion Pretreatment on GSH-Px,SOD and MDA in Gastric Mucosa of Rats with Stress Ulcer

Objective：To observe the effects of moxibustion pretreatment on Glutathione Peroxidase（GSH-Px）,Superoxide Dismutase（SOD）,and Malondialchehyche（MDA）in gastric mucosa of rats with stress ulcer,and to investigate the mechanism of moxibustion pretreatment preventing the oxidized injury of gastric mucosa.Methods：Forty-eight healthy SD rats were randomly allocated into 4 groups,namely control group,model group,acupoint moxibustion group,and non-acupoint moxibustion group.The ulcer model was developed by restraint and water immersion stress,Ulcer index（UI）was calculated with Guth method,and the contents of GSH-Px,and MDA and SOD activity in the gastric tissues were measured with chromatometry method.Results：Compared those in the model group and nonacupoint moxibustion group,moxibustion at Zusanli（ST 36）could decrease the UI（P〈0.01）and MDA（P〈0.05）contents,and increase the activity of GSH-Px（P〈0.01）and SOD（P〈0.05）.Conclusion：Pretreatment of moxibustion at Zusanli（ST 36）could promote the recovery of gastric injury in rats induced by restraint and water immersion stress by enhancing the activity of GSH-Px and SOD,and lower MDA content.

Efficacy and effect on related brain-gut peptides of acupoint sticking therapy for functional dyspepsia

Objective:To observe the efficacy of acupoint sticking with Jianpi Tongjing Zhitong ointmerrt in the treatment of functional dyspepsia due to liver-qi stagnation and spleen deficiency and its effect on serum 5-hydroxytryptamine(5-HT)and ghrelin con tents.Methods:One hun dred patients with functi onal dyspepsia due to liver-qi stag nation and spleen deficiency were divided into a treatment group and a control group by the random number table method,with 50 cases in each group.The treatment group received acupoint sticking with Jianpi Tongjing Zhitong ointment and the control group was treated with mosapride citrate orally.Patients were treated for 4 weeks as a course.The therapeutic efficacy was compared after one-course treatment and the differences in gastric emptying rate,and serum 5-HT and ghrelin contents between groups were compared before and after treatment.Results:The total effective rate was 79.6%in the control group and 89.4%in the treatment group,showing significantly differe nt between groups(P<0.05).After treatme nt,the gastric empt ying rate and serum ghreli n con tent of the two groups in creased significantly,and the serum 5-HT content decreased significantly,the intra-group differe nces were significant(all P<0.01).After treatment,the gastric emptying rate and serum ghrelin content were significantly higher in the treatment group than those in the control group,while the serum 5-HT was significant lower in the treatment group,the inter-group differences were significant(all P<0.05).A negative correlation(r=-0.59)was observed between serum 5-HT content and gastric emptying rate,and a positive correlation(r=0.64)was observed between serum ghrelin content and gastric emptying rate,showing statistical significance(all P<0.01).Conclusion:Acupoint sticking with Jianpi Tongjing Zhitong ointment has a remarkable ciinical efficacy in treating patie nts with functional dyspepsia due to liver-qi stagnation and spleen deficiency and is able to in fluence the secretion of serum 5-HT and ghrelin-1 mproving the gastrointestinal motility through the regulation of related brain-gut peptides is suggested as an underlying mechanism for this therapy.