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THE INSULIN-LIKE ACTIVITY OF HUMAN SERUM (GROWTH FACTORS, FIBROBLASTS, BOUND INSULIN)

机译：人体血清的胰岛素样活性（生长因子，成纤维细胞，有界胰岛素）

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摘要

Use of in vitro isolated tissue bioassays for insulin resulted in numerous reports of insulin-like activity (ILA) that didn't exhibit the physicochemical properties of insulin; for instance, 90% of serum ILA determined by the rat fat pad assay was not abolished by anti-insulin serum. Aqueous adipose tissue extracts, biotin and heparin were found to increase ILA measured with the rat diaphragm assay, leading several investigators to propose an insulin-binding protein in human serum. This study was carried out to determine whether an insulin-binding protein exists in normal human serum and the extent to which serum growth factors contribute to the observed ILA.;A systematic examination of the ability of human serum and plasma components to bind exogenous radiolabeled insulin specifically and reversibly was performed using gel chromatography and dextran-coated charcoal adsorption according to methods previously employed to elucidate other hormone carriers. These studies demonstrated that 1.5-3.5% of radiolabeled insulin incubated with serum or plasma apparently became associated with a specific protein fraction, but that radioactivity was not dissociated from this material by an excess of unlabeled insulin or 8 M urea. Affinity chromatography revealed that more than 80% of the radioactivity in the fraction was bound to albumin, confirming the hypothesis that no insulin-binding protein exists in normal human serum and that exogenous radiolabeled insulin apparently associated with serum components represents "damaged" label irreversibly bound to serum proteins, particularly albumin.;A cultured fibroblast bioassay capable of discriminating between specific ILA (stimulation of glucose uptake rate) and the effects of growth factors (stimulation of cell proliferation) was developed in order to test the hypothesis that most serum ILA is due to the effects of growth factors. This assay was used to examine normal human serum fractionated by molecular size. More than 90% of total serum ILA (measured by total glucose uptake), 20% of which was specific, exhibited a molecular weight of about 250,000 daltons and was accompanied by virtually all of the serum's capacity to stimulate cell proliferation and 23% of serum immunoreactive insulin, confirming the hypothesis, but suggesting the existence of circulating insulin aggregates.
机译：使用体外分离的组织生物测定法进行胰岛素治疗后，产生了许多关于胰岛素样活性（ILA）的报道，但并未表现出胰岛素的理化特性。例如，通过大鼠脂肪垫测定法测定的90％血清ILA并未被抗胰岛素血清废除。发现用大鼠隔膜测定法测量的脂肪组织水提取物，生物素和肝素会增加ILA，从而导致一些研究者提出了人血清中的胰岛素结合蛋白。这项研究旨在确定正常人血清中是否存在胰岛素结合蛋白，以及血清生长因子在何种程度上有助于观察到的ILA。系统检查人血清和血浆成分结合外源放射性标记胰岛素的能力根据先前用于阐明其他激素载体的方法，使用凝胶色谱法和葡聚糖包被的木炭吸附法可逆地进行特异性和可逆性检测。这些研究表明，与血清或血浆一起温育的放射性标记胰岛素的1.5-3.5％显然与特定的蛋白质组分相关，但过量的未标记胰岛素或8 M尿素并未从这种物质上解离放射性。亲和色谱法显示该级分中超过80％的放射性与白蛋白结合，从而证实了以下假设：正常人血清中不存在胰岛素结合蛋白，而与血清成分明显相关的外源性放射性标记的胰岛素代表不可逆结合的“受损”标记血清蛋白，特别是白蛋白。；一种培养的成纤维细胞生物测定法能够区分特定的ILA（刺激葡萄糖摄取率）和生长因子的影响（刺激细胞增殖），以检验大多数血清ILA是由于生长因子的影响。该测定法用于检查按分子大小分级的正常人血清。总血清ILA的90％以上（通过总葡萄糖摄取量来衡量）（其中20％是特异性的）表现出约250,000道尔顿的分子量，并伴随着几乎所有血清刺激细胞增殖的能力和23％的血清免疫反应性胰岛素，证实了这一假设，但提示存在循环胰岛素聚集体。

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  • 作者

    KLEGERMAN, MELVIN EARL.;

  • 作者单位

    Loyola University Chicago.;

  • 授予单位 Loyola University Chicago.;
  • 学科 Biochemistry.
  • 学位 Ph.D.
  • 年度 1984
  • 页码 468 p.
  • 总页数 468
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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