Evidence of a Stimulatory Effect of Cyclic AMP on Pancreatic Lipase and Colipase Synthesis in Rats

The effects of endogenous and exogenous cyclic AMP on the synthesis of pancreatic lipase, colipase, and amylase were studied. Pancreatic lobules were prepared and incubated with forskolin, dibutyryl cyclic AMP (dbcAMP), and dibutyryl cyclic GMP (dbcGMP), respectively, in the presence of “S-cysteine”. The individual pancreatic enzymes were isolated by polyacrylamide gel electrophoresis, and the incorporation of radioactive cysteine into lipase, colipase, and amylase was determined. Incubation with forskolin (25 uM) rapidly increased lipase synthesis rate within 30 min, followed by an increase in colipase synthesis rate after 60 min of incubation. Amylase synthesis rate did not change during the 1st h of incubation but decreased slightly when incubated for 2h. Incubation of pancreatic lobules with dbcAMP (1 mM) for 1 h also stimulated the incorporation of cysteine into lipase and colipase by 21% and 25%, respectively, whereas incubation with dbcGMP had no effect on the synthesis rates of lipase and colipase. Neither dbcAMP nor dbcGMP had any effect on synthesis rate of amylase. It is concluded that cyclic AMP might be an important intracellular signal for the synthesis of pancreatic lipase and colipase in the rat     

脂蛋白脂酶基因PvuⅡ酶切位点多态性与胰岛素抵抗关系的研究

目的旨在探讨脂蛋白脂酶基因第6内含子PvuⅡ酶切位点多态性与胰岛素抵抗、2型糖尿病的发生之间是否有关联。方法随机选取163例2型糖尿病患者作为病例组，106例正常人作为正常对照组，对第6号内含子PvuⅡI酶切位点进行多态性分析。结果病例组中P＋P＋组高密度脂蛋白胆固醇水平明显低于P-P-组，而血清三酰甘油、胰岛素抵抗指数指标水平高于P-P-组。结论PvuⅡ酶切位点多态性与2型糖尿病中胰岛素抵抗有关。     

蛇床子素对动物体内雌二醇和脂酶的影响及其相互关系的研究

目的观察蛇床子素对体内血脂、雌二醇(E2)和脂酶的影响及其相互关系。方法在建立高脂血症小鼠模型的同时,分组给予蛇床子素10～40mg.kg-1,3wk后测定肝素化后血浆LPL和HL活性及血浆TC、TG和HDL-C水平。分组给予正常小鼠蛇床子素10～40mg.kg-1,1wk后用ELISA方法观测血清E2水平的变化。建立去卵巢大鼠模型,给予蛇床子素10mg.kg-1,12wk后测定血清E2、TC和TG水平。结果给予蛇床子素10～20mg.kg-1后,能升高高脂血症小鼠肝素化后血浆LPL、HL活性和正常小鼠血清E2水平(P<0.05或P<0.01),也可使高脂血症小鼠血浆TC、TG和LDL-C降低(P<0.05或P<0.01),升高HDL-C(P<0.01)。蛇床子素剂量增至40mg.kg-1时,虽能升高正常小鼠血清E2水平(P<0.01),但高脂血症小鼠的血浆LPL、HL活性反而降低,对降低血浆TC、TG、LDL-C和升高HDL-C水平的幅度也不如低剂量的蛇床子素。去卵巢大鼠给予蛇床子素10mg.kg-1后,能增加血清E2水平(P<0.05),也能降低血清TG水平(P<0.05),TC的水平也有一定的降低。结论较低剂量的蛇床子素可通过增加血中E2水平,提高LPL和HL活性而降低血脂水平,较高剂量的蛇床子素虽可进一步增加血中E2水平,但LPL和HL活性反而降低,导致调脂作用减弱。     

组织特异性脂蛋白脂酶在2型糖尿病大鼠表达变化的作用

目的比较2型糖尿病大鼠和正常大鼠骨骼肌和脂肪组织脂蛋白脂酶（LPL）基因表达的差异,探讨组织特异性LPL表达异常在胰岛素抵抗（IR）的发生中所起的作用。方法实验大鼠22只分2组：正常对照组10只,2型糖尿病组12只;分别取对照组和实验组各2只大鼠同侧大腿骨骼肌组织及腹部大网膜脂肪,同时取骨骼肌组织送电镜检查;分别从骨骼肌及脂肪组织中抽提RNA,经逆转录分别用Cy3、Cy5荧光标记,获得两组动物来源的cDNA探针;cDNA探针与含糖脂代谢相关基因的芯片杂交,结果由扫描仪扫描并用软件进行统计分析;半定量RT-PCR验证两组织部分基因表达水平。结果在电镜下,2型糖尿病组大鼠骨骼肌细胞内可见脂质沉积;2型糖尿病大鼠骨骼肌组织中LPL基因表达上调,脂肪组织LPL基因表达下调;骨骼肌及脂肪组织脂肪酸b氧化相关酶基因表达上调;用半定量RT-PCR证实了基因芯片的结果。结论2型糖尿病大鼠骨骼肌及脂肪组织特异性LPL表达变化在胰岛素抵抗的发病机制可能起一定作用。     

Lipoprotein Alterations and Plasma Lipoprotein Lipase Reduction in Familial Hemophagocytic Lymphohistiocytosis

ABSTRACT. Serum lipid abnormalities are common in familial hemophagocytic lymphohistocytosis (FHL), a disorder also characterized by fever, hepatosplenomegaly, pancytopenia and a prominent lymphohistiocytic accumulation in the mononuclear phagocyte system. The lipoprotein pattern in nine children with FHL was studied with a quantitative method measuring cholesterol and triglycerides in each major class of lipoproteins. Triglycerides were markedly elevated during active FHL in serum, very low density lipoproteins, and low density lipoproteins. Cholesterol was increased in very low density lipoproteins whereas both triglycerides and cholesterol were extremely low in high density lipoproteins. These lipoprotein abnormalities, reversible on successful therapy, are compatible with a depressed lipolytic activity. Post-heparin levels of lipoprotein lipase and hepatic lipase in plasma were studied in four children and found to be markedly low during active FHL. We suggest that inflammatory cytokines, which may strongly suppress lipoprotein lipase activity, can be important mediators in the pathophysiology of FHL and that they may participate in the development of the lipid abnormalities.     

人脂蛋白脂酶基因重组质粒的构建及其表达

目的研究野生型人脂蛋白脂酶(LPL)cDNA重组表达质粒的构建了及其在COS-1细胞中的表达。方法采用RT-PCR法从人大网膜脂肪组织获取LPL cDNA基因,以pcDNA3.1Zeo( )质粒作为载体,运用基因克隆技术构建野生型人LPLcDNA重组质粒,限制性内切酶酶切、PCR以及双向测序鉴定重组质粒;运用L ipofectam ine 2000TM将重组pcDNA3.1Zeo( )-LPLcDNA质粒导入COS-1细胞,RT-PCR法检测LPL mRNA,ELISA法和比色法分别检测细胞裂解液及细胞培养基中LPL浓度及活性。结果经限制性内切酶酶切及PCR鉴定,证实LPL基因已被连接到pcDNA3.1Zeo( )质粒中;DNA双向测序证实其产物与基因库中LPL基因序列完全一致。LPL mRNA和蛋白表达及其活性测定结果表明,pcDNA3.1Zeo( )-LPL cDNA重组质粒已转染入COS-1细胞中。结论实验成功构建野生型人LPL cDNA重组表达质粒,并证实其能在COS-1细胞中有效表达。     

脂蛋白脂酶在胰岛素抵抗和动脉粥样硬化的发病中的矛盾作用

脂蛋白脂酶为甘油三酯代谢的限速酶,脂蛋白脂酶因活性和含量而改变其脂解功能,影响全身脂质代谢和分布,产生的血脂紊乱、高甘油三酯血症、低HDL血症是胰岛素抵抗和动脉硬化的基础。同时,脂蛋白脂酶对动脉粥样硬化和胰岛素抵抗形成具有截然不同的矛盾作用。     

脂蛋白脂酶与脑血管疾病

研究发现,脂蛋白脂酶(LPL)在调节体内甘油三酯(TG)代谢和血浆脂蛋白(LDL、HDL-C、VLPL)水平方面发挥关键作用,且与脑卒中等有关。随着医学分子生物学技术的发展,在分子水平上探讨脑血管疾病的发生与发展越来越受到人们的关注。LPL基因多态性与动脉粥样硬化性疾病或卒中的关系成为近年来的研究热点。这些基因多态性与血脂异常、动脉粥样硬化和脑血管疾病之间存在一定的关系。     

脂质代谢与妊娠高血压疾病的研究进展

内皮细胞损伤是妊娠期高血压疾病一系列病理生理变化的关键环节,脂代谢与内皮损伤直接相关,因此,推测与脂代谢有关的关键物质脂蛋白脂酶、载脂蛋白E可能在妊娠期高血压疾病中起一定作用.     

一种新的脂蛋白脂肪酶基因突变（C^56→T）

目的：筛查国人（天津地区）脂蛋白脂肪酶基因突变情况，并探讨其对血脂水平的影响。方法：利用聚合酶链反应-单链构象多态性分析技术，对386例患者（血脂正常组278例，血脂异常组108例）的脂蛋白脂肪酶基因进行突变筛查，对可疑突变的扩增样品进行DNA序列测定。结果：在386例样本中，检出1例外显子3 C^56→T（Leu^103→Leu）同义突变杂合子。结论：新LPL突变（C^56→T）的发现，对进一步阐述IJPL结构与功能的关系有重要的参考价值。