钆和镱对人红细胞膜脂及膜蛋白的作用

利用荧光偏振,自旋标标顺磁共振波谱和激光拉曼技术研究了钆和镱对人红细胞膜结构和功能的影响。结果表明,低浓度的Ｇｄ３＋（０．５μｍｏｌ／Ｌ）对（Ｎａ＋＋Ｋ＋）－ＡＴＰ酶和Ｍｇ２＋－ＡＴＰ酶有轻微的激活作用,而随着其浓度的增大,则明显抑制酶的活性,Ｇｄ３＋与Ｙｂ３＋和人红细胞膜作用后,降低膜脂流动性,并使膜蛋白酰胺Ｉ＇－α螺旋振动强度减弱．     

我国青年人红细胞膜血型糖蛋白变异的筛查

采用免疫印迹技术首次调查我国人群红细胞膜血型糖蛋白(Glycophorins; GP)的变种。受检者114人,年龄17—25岁,男80名,女34名。以对GP分子不同区域具特异性的4种抗血清为探针,调查发现3个类型的10例变种,总检出率达8.8％。其中汉族的检出率为5.7％,黎族为25％,其余民族中未检出变种。4例Ⅰ型先证者红细胞膜GP的免疫印迹图谱与st~a表型相似,其中1例经血清学检查确证。1例Ⅱ型缺失δGP。其余5例Ⅲ型变种尚未见有文献报道。7例GP变种红细胞膜的唾液酸含量明显高于正常人。     

人干细胞实验动物嵌合体模型的研究进展

动物模型是疾病研究、发病机制、药物治疗的必要工具,目前一些困扰人类健康的重大疾病如艾滋病、乙型肝炎等因为还没有能反映人类疾病发病机理的理想动物模型。人干细胞是能在体外长期培养的、高度未分化的全能细胞系,亚全能细胞系和分化的干细胞等。如果能将人的干细胞成功移植入实验动物体内形成人源化嵌合体动物,有希望为艾滋病、肝炎等的研究制备适当的模型。人类干细胞在动物中的移植研究中主要的实验动物是绵羊,小鼠等,本文介绍了人干细胞在动物体内移植的研究进展。     

稀土离子对磷脂酰胆碱脂质体及人红细胞膜自由基氧化的影响

通过荧光和电泳方法研究了稀土离子对磷脂酰胆碱（PC）脂质体及人红细胞膜脂质过氧化的影响．结果表明稀土离子（除钇外）都能够强烈的抑制膜的脂质过氧化,其作用强度随不同的稀土离子可有较大的差别．稀土离子对分离的人红细胞膜的脂质过氧化的抑制作用比对PC脂质体更强．但是,对完整红细胞用稀土离子处理反而会导致膜的脂质过氧化大大加强．     

我国人红细胞膜MiⅢ血型糖蛋白的基因结构分析

在１１４名青年人中筛查出的两例血型糖蛋白（ＧＰ）变种,携有ＭｉⅢ基因特殊的变异片段．先证者均为海南省黎族男性,属杂合子．借助聚合酶链式反应（ＰＣＲ）获得跨越ＭｉⅢ基因外显子２～４的基因组序列,再进行被扩增ＤＮＡ的直接测序,确证其基因结构属（δ－α－δ）杂化体．通过基因的微转换机理,δ基因的假外显子在其３＇端同显示５＇剪接信号的α基因外显子３及内含子３融合,前两者形成一组合外显子３．ＭｉⅢ基因的近端（δ－α）断点（Ｂｒｅａｋｐｏｉｎｔ）在组合外显子３内（第８２５～８５０位核苷酸）;而远端（α－δ）断点则在内含子３内（第９０４～９６８位核苷酸）．     

用稳态荧光探针研究竹红菌乙素光敏损伤对人红细胞膜流动性的影响

本文以红细胞膜为材料,用了三种稳态荧光探针研究了HB光敏作用引起人红细胞膜流动性的改变.实验结果表明在HB光敏作用下,膜的旋转扩散速度和侧向扩散速度均发生明显变化,ANS和DPH探针测得HB引起膜流动性降低,也就是膜粘度增加,用芘探针结果则表明膜的侧向扩散变慢.本文还对HB光敏作用的机理进行了探讨,我们观察了数种单重态氧猝灭剂,羟自山基猝灭剂和抗氧化剂对于光敏作用的影响,分别测定了膜流动性和膜的内源荧光的变化,发现在HB光敏作用中,除了~1O_2的作用之外,还存在其它自由基的作用.在HB与HA光敏能力的比较中发现,在比较高一些浓度条件下,存在着HB大于HA的趋向.     

竹红菌乙素敏化的人红细胞膜结构光损伤的Raman光谱特征

采用Raman光谱从分子水平揭示了竹红菌乙素光敏损伤的人红细胞膜发生膜蛋白交联和膜脂脂质过氧化导致其功能变化 ;膜流动性和离子通透性增加的本质是竹红菌乙素产生的活性氧 ( ¹O₂ ,O₂ ^-·和·OH等 )破坏了红细胞膜的有序结构 ,使膜蛋白主链结构的α 螺旋、β 折叠明显减少 ,无规卷曲增加并使其侧链结构的巯基基团、吲哚环、对羟苯基环、单基取代苯基环等也明显减少 .与此同时 ,随着光照时间的增加 ,膜脂的反式构象呈先增加后减少的趋势 ,它的扭曲构象则正好相反 .膜蛋白和膜脂构象不灵敏的CH₂ 和CH₃弯曲振动谱线的明显下降 ,揭示它们有链的断裂 .     

大强度训练及恢复后大鼠红细胞变形能力和红细胞膜蛋白的变化

目的 :探讨运动对红细胞变形性和红细胞膜蛋白的影响及其相互关系。方法 :设计不同强度的训练方案 ,用激光衍射法测定红细胞变形能力 ,用SDS PAGE方法测定一定体积大鼠红细胞膜中的重要蛋白带 3蛋白 (band 3)和肌动蛋白 (actin)的含量 ,研究运动即刻和恢复后红细胞变形性及膜蛋白的变化。结果 :长期的运动训练会促进大鼠红细胞变形能力的改善和红细胞膜band 3蛋白和actin的良好发展 ,一次大强度训练会引起红细胞膜band 3蛋白和actin含量的减少 ,大鼠红细胞变形能力降低 ,一周和二周的大强度训练会提高恢复期大鼠红细胞的变形能力和红细胞膜band 3蛋白和actin含量。结论 :运动训练造成的红细胞膜蛋白含量的变化 ,导致了红细胞膜结构的改变 ,从而影响红细胞变形能力 ,可能是训练对红细胞变形能力的作用机制之一。     

荧光素酶标的人肝癌细胞裸鼠异种移植瘤模型的生物发光成像和PET-CT成像比较

目的利用荧光素酶基因标记的人肝癌细胞株BEL-7402建立裸鼠肝原位移植模型,及小鼠肝原位移植模型的生物发光和小动物PET-CT成像的比较。方法构建表达荧光素酶基因的真核表达载体并将其转入人肝癌细胞BEL-7402,经梯度浓度G418筛选获得稳定表达荧光素酶基因的细胞克隆并扩大培养。BALB/cA-nu裸鼠肝门静脉接种5×105个发光细胞使其成瘤,活体荧光成像和小动物PET-CT成像系统观察肿瘤的生长情况。结果获得了稳定表达Luc的人肝癌细胞株,将其接种到裸鼠体内,活体荧光成像系统观察发现能够成瘤,小动物PET-CT影像观察发现小鼠肝脏边缘对18 F-FDG有高摄取区域。结论利用荧光素酶基因标记的人肝癌细胞BEL-7402成功建立了原位肝癌裸鼠模型,小动物活体成像结合小动物PET-CT技术为原位肿瘤模型的建立提供了一种新的可靠的技术,为进一步研究肝癌生长转移机制和药物开发提供了新的有用工具。     

基于数据挖掘及动物实验探讨维持洛哌丁胺诱导便秘小鼠模型稳定性的研究

目的 通过文献数据挖掘与实验研究相结合的方法,挖掘洛哌丁胺诱导便秘小鼠模型造模特点及影响因素,为建立稳定的实验便秘模型提供一定参考。方法 文献研究部分以便秘及动物模型为主题词,检索中英文数据库,筛选使用洛哌丁胺诱导便秘小鼠模型的实验研究,提取资料并进行分析;动物实验部分,采用雄性C57BL/6小鼠,给予5 mg/kg及10 mg/kg的洛哌丁胺灌胃,每日给药1次。从含水率、首次黑便时间、小肠推进率等评价造模效果,观察洛哌丁胺不同剂量及给药时间对便秘小鼠的影响。结果 纳入符合标准的文献69篇,洛哌丁胺给药剂量多为5、10 mg/kg,多用灌胃给药,频率为给药1次,给药时间多为30 min。根据文献研究结果,实验部分从造模第1天开始,5 mg/kg及10 mg/kg组与空白组相比含水率显著降低,差异具有统计学意义(P<0.05),而造模第7～14天,5 mg/kg组与10 mg/kg相比含水率明显升高(P<0.05),对比造模3、7、14 d后含水率变化情况,各模型组均在停药1 d后升高,至停药后14 d含水率均保持在较高水平;对比造模3、7、14 d的首次黑便时间,造模7、1...     

Abnormality of Long-Chain Fatty Acids in Erythrocyte Membrane Sphingomyelin from Patients with Adrenoleukodystrophy

Abstract: We have devised an analytical method for the determination of fatty acid composition of erythrocyte membrane sphingomyelin by chemical ionization mass spectrometry combined with capillary column gas-liquid chromatography. Fatty acid composition of erythrocyte membrane sphingomyelin from 8 patients with adrenoleukodystrophy (ALD) and 16 healthy controls were examined by this method. The ratio of hexacosanoic acid (C_26.0) to docosanoic acid (C_22:0) in erythrocyte membrane sphingomyelin from ALD patients was 2.6-fold higher than that of the controls. This result suggests that biochemical diagnosis of ALD is possible by the analysis of fatty acid composition of erythrocyte membrane sphingomyelin. Furthermore, it demonstrates that biochemical abnormality in ALD is the generalized abnormal metabolism of very long-chain saturated fatty acids.     

The Relationship Between Plasma and Brain Quinolinic Acid Levels and the Severity of Hepatic Encephalopathy in Animal Models of Fulminant Hepatic Failure

Abstract: Quinolinic acid is an excitatory, neurotoxic tryptophan metabolite proposed to play a role in the pathogenesis of hepatic encephalopathy. This involvement was investigated in rat and rabbit models of fulminant hepatic failure at different stages of hepatic encephalopathy. Although plasma and brain tryptophan levels were significantly increased in all stages of hepatic encephalopathy, quinolinic acid levels increased three- to sevenfold only in the plasma, CSF, and brain regions of animals in stage IV hepatic encephalopathy. Plasma-CSF and plasma-brain quinolinic acid levels in rats and rabbits with fulminant hepatic failure were strongly correlated, with CSF and brain concentrations ∼10% those of plasma levels. Moreover, there was no significant regional difference in brain quinolinic acid concentrations in either model. Extrahepatic indoleamine-2,3-dioxygenase activity was not altered in rats in stage IV hepatic encephalopathy, but hepatic l -tryptophan-2,3-dioxygenase activity was increased. These results suggest that quinolinic acid synthesized in the liver enters the plasma and then accumulates in the CNS after crossing a permeabilized blood-brain barrier in the end stages of liver failure. Furthermore, the observation of low brain concentrations of quinolinic acid only in stage IV encephalopathy suggests that the contribution of quinolinic acid to the pathogenesis of hepatic encephalopathy in these animal models is minor.     

Studies on the mechanism of capacitation II. Evidence for lipid transfer between plasma membrane of rat sperm and serum albumin during capacitation in vitro

1. 1. Evidence has been provided for the transfer of phosphatidyl[¹⁴C]choline and [³H]cholesterol between bovine serum albumin and cauda epididymal rat spermatozoa in Krebs-Ringer bicarbonate medium, which can promote sperm capacitation.

2. 2. An analysis of the lipid composition in both albumin and spermatozoa revealed that phospholipid levels decreased in the protein and increased by roughly comparable amounts in sperm cells during incubation in vitro.

3. 3. Cholesterol (free + ester) increased in albumin and decreased in spermatozoa. Changes in the amount of esterified cholesterol were solely responsible for the increase associated with albumin, whereas whole sperm cell extracts showed a significant decline in free cholesterol.

4. 4. The composition of albumin-bound fatty acids did not alter appreciably as a result of incubation with spermatozoa.

5. 5. Rates of [¹⁴C]palmitic acid utilization by spermatozoa suggest that lipid synthesis accounted for less than 5% of the changes observed under the conditions of this study.

6. 6. These results are interpreted as broadly supporting our previous proposal that lipid exchange between albumin and sperm cells is implicated in sperm capacitation in vitro. Specifically, the results are compatible with the idea that a decreased cholesterol/phospholipid ratio in the sperm plasma membrane facilitates this transformation.