P-glycoprotein and ‘lipid rafts’: some ambiguous mutual relationships (floating on them, building them or meeting them by chance?)

P-glycoprotein (P-gp) is an active membrane transporter responsible for cell detoxification against numerous amphiphilic compounds, leading to multidrug resistance in tumor cells. It displays entangled connections with its membrane environment since it recognizes its substrates within the cytosolic leaflet and it also translocates some endogenous lipids to the exoplasmic leaflet. Regarding its relationships with membrane microdomains, ‘lipid rafts’, a literature analysis concludes that (i) P-gp also exists in rafts and non-raft membrane domains, depending on the cell considered, the experimental conditions and the method used to test it; (ii) cholesterol has a positive influence on P-gp function, and this may be a direct effect of the free cholesterol present in membrane or an indirect effect mediated by the cholesterol-enriched microdomains; (iii) when present in rafts, P-gp interacts with protein partners regulating its activity; (iv) P-gp is a lipid translocase that handles the raft-constituting lipids with particular efficiency, and it also influences membrane trafficking in the cell. Received 18 November 2005; received after revision 23 December 2005; accepted 12 January 2006     

Antigen presentation by CD1 molecules and the generation of lipid-specific T cell immunity

It is now well demonstrated that the repertoire of T cells includes not only cells that recognize specific MHC-presented peptide antigens, but also cells that recognize specific self and foreign lipid antigens. This T cell recognition of lipid antigens is mediated by a family of conserved MHC class I-like cell surface glycoproteins known as CD1 molecules. These are specialized antigen-presenting molecules that directly bind a wide variety of lipids and present them for T cell recognition at the surface of antigen-presenting cells. Distinct populations of T cells exist that recognize CD1-presented lipids of microbial, environmental or self origin, and these T cells participate in immune responses associated with infectious, neoplastic, autoimmune and allergic diseases. Here we review the current knowledge of the biology of the CD1 system, including the structure, biosynthesis and trafficking of CD1 molecules, the structures of defined lipid antigens and the types of functional responses mediated by T cells specific for CD1-presented lipids.     

力竭运动对小鼠体内脂质过氧化作用及肾上腺超微结构的影响

观察了力竭运动对小鼠体内脂质过氧化作用及对肾上腺超微结构的影响．结果表明：连续７次力竭运动后，小鼠肝内丙二醛（ＭＤＡ）含量明显升高；肾上腺皮质及髓质细胞呈现了高度的可变性．提示力竭运动后，小鼠体内所产生的脂质过氧化代谢产物增加，进而可导致细胞膜系及超微结构的改变     

预知灵对小白鼠肝微粒体LPO及SOD活性的影响

分别给小鼠以大、中、小剂量的预知灵溶液灌胃,测定肝微粒体脂质过氧化物(LPO)及超氧化物歧化酶(SOD)的活性,来探讨预知灵对小白鼠肝微粒体LPO及SOD的影响.试验结果表明,大、中剂量的预知灵和人参煎液均能显著降低肝微粒体LPO水平并提高其SOD的活力.提示预知灵和人参煎液有抗衰老作用,并且预知灵抗衰老作用明显优于人参煎液(P<0.01).     

榆黄蘑发酵液的抗衰老研究

本文以“中央衰老钟”和“自由基”学说为依据,以昆明种十月龄雄性小鼠为实验对象,对榆黄蘑发酵液的抗衰老作用进行了研究.结果表明,榆黄蘑发酵液能抑制脑B型单胺氧化酶(MAO—B)的活性(29.48％);对肝MAO—B活性无显著影响(P>0.05);能降低肝过氧化脂质(LPO)的含量(34.62％);使心肌脂褐素含量下降(40.50％);增高皮肤羟脯氨酸(HYP)的含量(6.41％)以及提高红细胞中超氧化物歧化酶(SOD)的活性(14.10％).据此,可以认为榆黄蘑发酵液具有良好的延缓衰老的作用。     

Membrane fusion: the process and its energy suppliers

Membrane fusion constitutes a pivotal process in eukaryotic cell physiology. Both specialized proteins and membrane lipids play key roles in fusion. Here, our current understanding of the mechanism of membrane fusion is reviewed. The focus is on the relatively simple and well-understood proteinaceous fusion machinery of enveloped viruses and the physical properties of lipids that appear to be of great relevance for fusion progression. Recent observations suggest that viral fusion proteins use packed conformational energy and bilayer-destabilizing domains to (i) bring participating membranes into intimate contact, (ii) merge proximal lipid monolayers through highly curved stalk/hemifusion intermediates, and (iii) generate a lipid-containing fusion pore, thereby terminating the fusion process. Received 4 January 2002; received after revision 3 April 2002; accepted 5 April 2002     

枸杞降血脂作用的实验研究

以大鼠为实验动物,研究了枸杞对大鼠血脂水平的影响,结果表明,枸杞可有效降低血清中甘油三脂（TG）,胆固醇（TC）,低密度脂蛋白（LDL－C）含量及LDL－C／HDL－C（高密度脂蛋白）比值,具有明显的降血脂作用。     

双氢杨梅树皮素对链脲霉素所致糖尿病大鼠的降糖作用

用链脲霉素（ＳＴＺ）所致的大鼠糖尿病作模型,给予双氢杨梅树皮素（ＡＰ）连续治疗３０ｄ,探讨ＡＰ的降糖作用机理。结果表明：ＡＰ能使ＳＴＸ糖尿病大鼠的高血糖反应减轻,增加血清中ＳＯＤ－ｃｕ．ｚｎ活性,降低ＭＤＡ含量,对血脂中的甘油三酯（ＴＧ）水平有降低趋势;可提高血清中胰岛素水平。组织学研究可见ＡＰ组大鼠胰腺组织中的胰岛数目较模型组增多,淋巴细胞浸减少,炎症反应减轻。其作用机理可能是通过ＡＰ的抗氧化作     

灵芝降血脂作用的实验研究

以大鼠为实验动物,研究了灵芝对大鼠血脂水平的影响,结果表明,灵芝可有效降低血清中甘油三脂(TG)、胆固醇(TC)、低密度脂蛋白(LDL—C)含量及LDL—C／HDL—C比值,具有明显的降血脂作用．