宫内发育迟缓与胰岛素样生长因子及其结合蛋白关系的研究

为探讨宫内发育迟缓（IUGR）的发生机制,检测了86例新生儿脐血胰岛素样生长因子－1（IGF－1）、胰岛素样生长因子结合蛋白－3（IGFBP－3）水平,并分析上述指标变化与胎儿期生长的关系。将86例新生儿分为两组,IUGR（即小于胎龄儿）组22例,适于胎龄儿（AGA）组64例,采用竞争性放射免疫分析法（RIA）测定两组脐血IGF－1水平,非竞争性免疫放射分析法（IRMA）测定IGFBP－3水平。结果显示,与AGA组相比,IUGR组脐血IGF－1和IGFBP－3水平显著降低（P＜0．001）;IGF－1水平随胎龄及出生体重增加而增加（P＜0．01）;IGFBP－3水平与胎龄及出生体重呈相关（P＜0．01）;IGF－1与IGFBP－3呈正相关（P＜0．01）。认为IUGR与IGF－1及其结合蛋白密切相关,不论何种原因引起的IUGR,其脐血IGF－1、IGFBP－3水平均低,IGF－1水平下降与IGFBP－3下降相伴随;脐血IGF－1、IGFBP－3水平与胎龄及出生体重呈正相关,随着胎龄的增加和出生体重的增长,IGF－1、IGFBP－3水平不断升高。     

Interactions of growth hormone secretagogues and growth hormone-releasing hormone/somatostatin

The class of novel synthetic compounds termed growth hormone secretagogues (GHSs) act in the hypothalamus through, as yet, unknown pathways. We performed physiologic and histochemical studies to further understand how the GHS system interacts with the well-established somatostatin (SRIF)/growth hormone-releasing hormone (GHRH) neuroendocrine system for regulating pulsatile GH secretion. Comparison of the GH-releasing activities of the hexapeptide growth hormone-releasing peptide-6 (GHRP-6) and GHRH administered intravenously to conscious adult male rats showed that the pattern of GH responsiveness to GHRP-6 was markedly time-dependent, similar to that observed with GHRH. Immunoneutralization of endogenous SRIF reversed the blunted GH response to GHRP-6 at trough times, suggesting that GHRP-6 neither disrupts nor inhibits the cyclical release of endogenous hypothalamic SRIF. By striking contrast, passive immunization with anti-GHRH serum virtually obliterated the GH responses to GHRP-6, irrespective of the time of administration. These findings suggest that the GHSs do not act by altering SRIF release but, rather, stimulate GH release via GHRH-dependent pathways. Our dual chromogenic and autoradiographic in situ hybridization experiments revealed that a subpopulation of GHRH mRNA-containing neurons in the arcuate (Arc) nucleus and ventromedial nucleus (VMN) of the hypothalamus expressed the GHS receptor (GHS-R) gene. These results provide strong anatomic evidence that GHSs may directly stimulate GHRH release into hypophyseal portal blood, and thereby influence GH secretion, through interaction with the GHS-R on GHRH- containing neurons. Altogether, these findings support the notion that an additional neuroendocrine pathway may exist to regulate pulsatile GH secretion, possibly through the influence of the newly discovered GHS natural peptide, ghrelin.     

The role of the growth hormone-insulin-like growth factor axis in glucose homeostasis.

Homeostatic mechanisms normally maintain the plasma glucose concentration within narrow limits despite major fluctuations in supply and demand. There is increasing evidence that the growth hormone (GH)-insulin-like growth factor (IGF) axis may play an important role in glucose metabolism. GH has potent effects on intermediary metabolism, some of which antagonize the actions of insulin. In contrast, IGF-I has insulin-like actions, which are, in the case of glucose metabolism, opposite to those of GH. There is often deranged glucose metabolism in situations where GH is deficient or in excess. The clinical administration of GH or IGF-I results in altered glucose metabolism and changes in insulin resistance. Despite these observations, the precise role of GH and IGF-I and their interactions with insulin in controlling normal glucose homeostasis are unknown. In diabetes, GH secretion is abnormally increased as a result of reduced portal insulin resulting in impaired hepatic IGF-I generation. Evidence suggests that this may contribute to the development of diabetic microvascular complications. IGF-I 'replacement' in diabetes is under investigation and new methods of delivering IGF-I as a complex with IGFBP-3 offer exciting new prospects.     

Epidermal growth factor-stimulated rabbit oesophageal mucosal growth: Role of polyamines

Abstract Factors operative in oesophageal mucosal growth are poorly characterized. Epidermal growth factor (EGF) has been shown to stimulate mucosal growth throughout the gastrointestinal tract. The present study was performed to test the hypothesis that polyamine biosynthesis is required for stimulation of epithelial growth by EGF in oesophageal mucosa. Using an in vitro explant model, oesophageal mucosal growth was quantified in the presence or absence of EGF and α-difluoromethylornithine (DFMO), a specific inhibitor of polyamine synthesis. Administration of 50 nmol/L EGF significantly increased the rate of epithelial growth in oesophageal explants. Treatment with DFMO for 3 and 7 days not only depleted the tissue polyamines putrescine, spermidine and spermine, but also significantly impaired mucosal growth. The inhibitory effect of DFMO on mucosal growth was partially but significantly prevented when exogenous putrescine was given. Additionally, stimulation of epithelial growth by EGF was also blocked by depletion of cellular polyamines in DFMO-treated oesophageal explants. These results indicate that EGF stimulates epithelial growth of oesophageal mucosa at least partly through a process involving polyamine biosynthesis.     

Outcome of growth hormone therapy in children with growth hormone deficiency showing an inadequate response to growth hormone-releasing hormone

Saizen (recombinant growth hormone [GH]), 0.2 mg/(kg x wk), was given in an open-label fashion for an average of 51 mo to 27 children with presumed idiopathic GH deficiency who had withdrawn from a trial of Geref (recombinant GH-releasing hormone [GHRH] 1-29) because of inadequate height velocity (HV) (25 children), the onset of puberty (1 child), or injection site reactions (1 child). Measurements were made every 3-12 mo of a number of auxologic variables, including HV, height standard deviation score, and bone age. The children in the study showed excellent responses to Saizen. Moreover, first-year growth during Saizen therapy was inversely correlated with the GH response to provocative GHRH testing carried out 6 and 12 mo after the initiation of Geref treatment. These findings indicate that GH is effective in accelerating growth in GH-deficient children who do not show or maintain a satisfactory response to treatment with GHRH. In addition, they suggest that the initial response to GH therapy used in this way can be predicted by means of provoc-ative testing.     

Increased epidermal growth factor in experimental diabetes related kidney growth in rats

Summary Renal enlargement is a characteristic feature of human and experimental diabetes mellitus that may be predictive of subsequent nephropathy. In the streptozotocin diabetic rat kidney growth rapidly follows the induction of experimental diabetes but the mechanisms responsible for this growth are poorly understood. Epidermal growth factor (EGF) is a potent mitogen for renal tubular cells. Thirty one male Sprague-Dawley rats aged 13 weeks were randomised to receive either streptozotocin (diabetic, n = 20) or buffer (control, n = 11). Animals were studied on days 1, 3, 5 and 7 following streptozotocin. Diabetes was associated with a 3-fold increase in urinary EGF excretion (223 ± 15 vs 59 ± 5 ng/day, mean ± SEM, diabetic vs control, p < 0.0001) and 3–6 fold increase in renal EGF mRNA relative to controls (p < 0.001). A transient rise in kidney EGF protein was noted on day 1. There was no difference between diabetic and control animals with regard to intrarenal sites of EGF expression or in plasma EGF. These data suggest that the increased urinary EGF excretion in diabetic animals is the result of enhanced local production and that EGF is not stored for a prolonged period within renal tubular cells but is released following its synthesis. In the context of the known intrarenal actions of EGF this growth factor may play a role in the pathogenesis of diabetes related kidney growth. [Diabetologia (1997) 40: 778–785] Received: 16 December 1996 and in revised form: 4 March 1997     

非小细胞肺癌患者血清血管内皮生长因子、血小板衍生生长因子和表皮生长因子受体测定的临床意义

目的 探讨血清血管内皮生长因子(vascular endothelial growth factor,VEGF)、血小板衍生生长因子(platelet-derived growth factor,PDGF)和表皮生长因子受体(epidermal growth factor receptor,EGFR)测定在非小细胞肺癌(non-small cell lung cancer,NSCLC)诊断和预后判定中的意义.方法 采用双抗体夹心ABC-ELISA法测定31例NSCLC患者及30名健康者血清VEGF、PDGF和EGFR的含量.结果 NSCLC患者血清VEGF、PDGF和EGFR测定值均高于健康对照组(P值均＜0.01).血清VEGF、PDGF和EGFR测定值与NSCLC病理分型无关(P值均＞0.05),与远处转移有关,远处转移组的测定值高于未转移组(P＜0.05～0.01).NSCLC患者血清VEGF与PDGF测定值之间呈显著正相关(r=0.641,P＜0.01),血清VEGF和EGFR测定值呈正相关(r=0.369,P＜0.05).结论 检测血清VEGF、PDGF和EGFR水平对NSCLC的诊断和预后判定具有一定价值.     

Effects of epidermal growth factor on neonatal pancreatic growth in the guinea pig

Summary Conclusion EGF and/or transforming growth factor-α (TGF-α) are likely to be important in the rapid pancreatic growth that occurs in the neonatal guinea pig. Background Rapid pancreatic growth is observed during the neonatal period in the guinea pig. The growth factors that are involved are not known but may include members of the EGF family. Methods Mini-osmotic pumps were implanted on the day of birth for continuous infusion of EGF (30 μg/d). Pancreatic DNA, RNA, and protein contents were determined at 4 and 15 d, along with wet weights of the pancreas, duodenum, jejunoileum, colon, and gallbladder. Pancreatic EGF and TGF-α concentrations were measured in adult controls, in control neonates at 1, 4, 8, and 15 d, and also at d 4 and 15 in guinea pigs receiving either EGF or the cholecystokinin receptor antagonist devazepide (25 nmol/kg/h). Results EGF infusion significantly increased the weight of the stomach and duodenum at 4 d and all the gastrointestinal organs, including the pancreas, at 15 d. Exogenous EGF increased pancreatic DNA, RNA, and protein content at 4 and 15 d. Endogenous EGF and TGF-α concentrations in the pancreas were significantly higher at birth than in adults (P<0.001 andP<0.01, respectively) and declined during the first 2 wk postpartum. At 15 d, EGF concentrations remained significantly higher than adult levels (P<0.01), but TGF-α concentrations had declined to adult values. Infusion of EGF decreased concentrations of endogenous EGF in the pancreas at 4 and 15 d (bothP<0.05) and decreased TGF-α concentrations at 4 d (P<0.001). Devazepide infusion caused a significant decrease in endogenous pancreatic EGF concentrations at 15 d (P<0.05).     

探讨TGFβ1、PDGF、VEGF对特发性肺纤维化诊断及病情评估的临床意义

目的探讨分泌转化生长因子-β、血小板衍生生长因子、血管内皮生长因子在特发性肺纤维化(IPF)患者支气管肺泡灌洗液(BALF)和血清中的表达水平及评估病情进展的临床意义。 方法选择2014年1月至2018年12月在我院呼吸科诊治的35例IPF患者作为观察组,18例肺结节病患者(Ⅰ期)作为对照组;采用免疫印迹观察TGFβ1、PDGF、VEGF在IPF患者血清中是否存在表达;用酶联免疫吸附法(ELISA)观察2组患者BALF和血清中TGFβ1、PDGF、VEGF的表达水平;最后分析IPF患者BALF和血清中TGFβ1、PDGF、VEGF表达水平与肺功能及血氧饱和度的相关性。 结果TGFβ1、PDGF、VEGF细胞印在IPF患者血清存在表达;与对照组相比,BALF及血清中的TGFβ1、PDGF、VEGF表达上调(P<0.05);IPF组患者BALF及血清中TGFβ1、PDGF、VEGF表达水平与肺功能中FVC%、FEV₁%和DLCO%呈负性相关(P<0.05);与血氧饱和度也呈显著负相关(P<0.05)。 结论IPF患者BALF和血清中TGFβ1、PDGF、VEGF的表达水平明显升高;TGFβ1、PDGF、VEGF与患者的肺功能及血氧饱和度呈负相关,可作为评估IPF患者病情的临床评价指标。     

风湿性心脏病心房颤动患者心房组织肝细胞生长因子结缔组织生长因子与转化生长因子β1基因表达的研究

目的 观察风湿性心脏病心房颤动患者心房组织中肝细胞生长因子(HGF)、结缔组织生长因子(CTGF)、转化生长因子(TGF)-β1基因表达的变化.方法 35例行心脏手术者于术中获取的右心耳(约200 mg)分为3组,风湿性心脏病27例,其中窦性心律者8例,慢性持续性心房颤动者19例(≥16个月),分别列为风湿性心脏病窦性心律组和风湿性心脏病心房颤动组,另先天性心脏病患者8例(均为窦性心律)作为对照组,以β-肌动蛋白为内参照基因,通过实时荧光定量聚合酶链反应(real time PCR)技术,测定各组心房组织中HGF、CTGF、TGF-β1与Ⅰ型和Ⅲ型胶原mRNA的含量,苏木素-伊红(HE)和Massom病理染色观察右心耳组织纤维化程度.结果 与对照组比较,CTGF、TGF-β1、Ⅰ型胶原、Ⅲ型胶原mRNA表达在风湿性心脏病窦性心律组和风湿性心脏病心房颤动组均显著增加(P<0.05),且风湿性心脏病心房颤动组与风湿性心脏病窦性心律组比较也明显增加(P<0.05);HGF在风湿性心脏病窦性心律组较对照组增加,但比较差异无统计学意义,而在风湿性心脏病心房颤动组HGF下降明显,与对照组和风湿性心脏病窦性心律组比较差异均有统计学意义(P<0.05);相关性分析显示风湿性心脏病心房颤动患者心房组织Ⅰ型胶原、Ⅲ型胶原、TGF-β1和CTGF的mRNA表达与左房直径和组织纤维化面积有相关性.结论 风湿性心脏病患者Ⅰ型胶原和Ⅲ型胶原mRNA表达增加,CTGF、TGF-β1mRNA表达上调.具有抗纤维化作用的HGF mRNA表达在心房颤动时下降,可能是使得风湿性心脏病患者心房颤动易于发生和维持的重要原因.     

Role of the growth hormone/insulin-like growth factor-1 paracrine axis in rheumatic diseases

OBJECTIVES: Hypothalamic-pituitary axis abnormalities have been associated with systemic disturbances in several rheumatic diseases. Longitudinal analysis of erythrocyte, serum, urinary and synovial fluid growth hormone (GH), insulin-like growth factor-1 (IGF-1), and somatostatin levels could provide important surrogate measures of disease activity in rheumatic diseases. METHODS: The authors reviewed the population and longitudinal studies literature on GH, IGF-1, and somatostatin levels in rheumatic disorders using the PubMed and Medlines databases from the National Library of Medicine. In addition to the literature search, primary data were analyzed for basal somatostatin levels in patients with hand, knee, and spine osteoarthritis (OA) as well as primary and secondary hip OA. RESULTS: A review of the literature supports the view that hypothalamic-pituitary axis dysfunction accompanies clinical symptoms in many rheumatic diseases. In studies from our laboratory, serum GH levels were elevated in patients with OA, rheumatoid arthritis (RA), fibromyalgia, and diffuse idiopathic skeletal hyperostosis but not in patients with gout, pseudogout, or systemic lupus erythematosus. In OA and RA, synovial fluid GH levels exceeded serum GH levels. However, the literature remains controversial regarding the significance of changes in IGF-1 levels in rheumatic disorders. Many studies support an inverse relationship between age and IGF-1. Elevated serum GH levels in various rheumatic diseases were not coupled to changes in serum IGF-1 in diffuse idiopathic skeletal hyperostosis, RA, and fibromyalgia. In particular, serum IGF-1 levels in OA were shown to be lower or no different compared with age-matched normal subjects. Further, in OA, impaired articular chondrocyte response to IGF-1 was attributed, in part, to low synovial fluid IGF-1 that further compromised IGF-1 chondrocyte responses as a result of increased levels of synovial fluid IGF-1 binding proteins. Of note, serum somatostatin levels and "specific" somatostatin receptor levels were often lower in RA and systemic lupus erythematosus, but basal serum somatostatin levels were generally not altered in OA. CONCLUSIONS: The results of these analyses support the view that some rheumatic diseases such as OA and diffuse idiopathic skeletal hyperostosis, heretofore considered to be purely focal and degenerative, could be reclassified as systemic metabolic disturbances. We propose that serum GH, IGF-1, and somatostatin levels be monitored on a longitudinal basis during the course of medical therapy of rheumatic diseases to determine the extent to which changes in clinical symptoms (exemplified by reduced pain and inflammation and improved range of joint motion) are accompanied by changes in the basal concentration of these hypothalamic/pituitary-related hormones.     

血小板衍化生长因子-BB与糖尿病肾病

血小板衍化生长因子-BB(PDGF-BB)是PDGF经典的存在形式之一,其在肾脏中的作用主要包括诱导肾脏系膜细胞增生,促进细胞外基质积聚及单核-巨噬细胞在肾组织浸润。PDGF-BB在糖尿病肾病肾脏中表达增高,高水平的PDGF-BB可引起肾小球系膜细胞增生和细胞外基质积聚,亦参与肾小管及其间质改变,从而在糖尿病肾病的发生发展中起着重要作用。PDGF-BB还能通过诱导转化生长因子-β表达协同促进糖尿病肾病肾纤维化的发展。阻止PDGF-BB表达及其信号转导将有可能是糖尿病肾病的一种治疗手段。     

重组人生长激素治疗青春期前生长激素缺乏症的临床观察

目的探讨重组人生长激素（ｒｈＧＨ）对青春期前特发性生长激素缺乏症（ＩＧＨＤ）患者的疗效。方法对３家医院的６３例ＩＧＨＤ以ｒｈＧＨ进行治疗,每晚临睡前皮下注射０．１ＩＵ／ｋｇ共６个月。结果６３例患儿身高平均增加（７．０±１．６）厘米,年生长速度由治疗前的（２．９±０．９）厘米／年,增加到（１４．０±３．２）厘米／年,身高标准差计分（ＳＤＳ）由治疗前的（－４．８±１．７）变为（－３．９±１．６）;体重也明显增加,但对骨龄无明显促进作用。治疗期间有３９．７％的患儿出现亚临床甲状腺功能低减,２２．４％的患儿于注射局部曾出现短暂的红肿或痒等,７．９％的患儿出现血清ＡＬＴ轻度升高,但所有这些现象均未影响患儿体格的线性增长。结论ｒｈＧＨ是治疗ＩＧＨＤ的一种安全、有效的促生长药物。     

The bone mineral density in acquired growth hormone deficiency correlates with circulating levels of insulin-like growth factor I.

Insulin-like growth factor I (IGF-I) is an important anabolic factor for osteoblasts in vitro. Low plasma levels of IGF-I have been observed in young men with osteoporosis. In the present study, we have studied bone mineral density (BMD) and the circulating levels of IGF-I and growth hormone (GH) in adults with acquired GH deficiency. BMD was determined by dual-energy x-ray absorptiometry in 17 men and 12 women (age 27-54 years). Spinal BMD was positively correlated with the plasma levels of IGF-I (r = 0.43, P = 0.019), with the median of GH values obtained by repeated sampling at night (r = 0.43, P = 0.0019), and with the peak of GH values during GHRH provocation test (r = 0.49, P = 0.039). The total BMD was positively related to plasma IGF-I and median of GH values, but not to peak GH by GHRH provocation. In a multiple regression analysis model, IGF-I, peak GH by GHRH provocation test and duration of GH deficiency explained 49% of the variation in spinal BMD. As compared to healthy controls, total, but not spinal, bone mass was lower in men with GH deficiency, but no clinical symptoms of osteoporosis were observed. The positive relationships between BMD and circulating IGF-I and other indices of GH secretion suggest that IGF-I has an endocrine effect on bone mass.     

Therapeutic aspects of growth hormone and insulin-like growth factor-I treatment on visceral fat and insulin sensitivity in adults

Growth hormone (GH) is generally considered to exert anti-insulin actions, whereas insulin-like growth factor I (IGF-I) has insulin-like properties. Paradoxically, GH deficient adults and those with acromegaly are both predisposed to insulin resistance, but one cannot extrapolate from these pathological conditions to determine the normal metabolic roles of GH and IGF-I on glucose homeostasis. High doses of GH treatment have major effects on lipolysis, which plays a crucial role in promoting its anti-insulin effects, whereas IGF-I acts as an insulin sensitizer that does not exert any direct effect on lipolysis or lipogenesis. Under physiological conditions, the insulin-sensitizing effect of IGF-I is only evident after feeding when the bioavailability of circulating IGF-I is increased. In contrast, many studies in GH deficient adults have consistently shown that GH replacement improves the body composition profile although these studies differ considerably in terms of age, the presence or absence of multiple pituitary hormone deficiency, and whether GH deficiency was childhood or adult-onset. However, the improvement in body composition does not necessarily translate into improvements in insulin sensitivity presumably due to the anti-insulin effects of high doses of GH therapy. More recently, we have found that a very low dose GH therapy (0.1 mg/day) improved insulin sensitivity without affecting body composition in GH-deficient adults and in subjects with metabolic syndrome, and we postulate that these effects are mediated by its ability to increase free 'bioavailable' IGF-I without the induction of lipolysis. These results raise the possibility that this low GH dose may play a role in preventing the decline of beta-cell function and the development of type 2 diabetes in these "high risk" subjects.     

Effects of growth factors on the growth and differentiation of mouse fetal liver epithelial cells in primary cultures

BACKGROUND AND AIMS: Growth factors (GF) are thought to affect the growth and differentiation of hepatocytes during liver development. However, in the midfetal liver, little is known concerning the role of GF. METHODS: The DNA synthesis of fetal liver epithelial cells (FLEC) in monolayer culture and the liver-specific gene expressions of FLEC in 3-D culture were examined in medium supplemented with various GF. RESULTS: DNA synthesis of FLEC was higher than that of adult hepatocytes without GF, and was increased by hepatocyte growth factor (HGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha). However, FLEC responded less to GF in terms of DNA synthesis than adult hepatocytes. The liver-specific gene expressions were increased in the presence of HGF, HB-EGF, bFGF and EGF. In embryonic day (E) 13.5 FLEC, this increase was more apparent in the presence of HB-EGF, whereas in E14.5 FLEC, it was more apparent in the presence of HGF. CONCLUSIONS: Hepatocyte growth factor, HB-EGF, bFGF, EGF and TGF-alpha increased DNA synthesis of FLEC. HGF, HB-EGF, bFGF and EGF led to an increase in liver-specific gene expressions; and their effects on differentiation differ as a function of gestation age.     

Thyrotropin-releasing hormone increases serum levels of growth hormone-releasing hormone and growth hormone in patients with acromegaly.

The effect of intravenous injection of thyrotropin-releasing hormone (TRH) on the plasma concentrations of growth hormone (GH) and growth hormone-releasing hormone (GHRH) was studied in seven patients with acromegaly and in five control subjects. TRH had no effect on plasma GH or GHRH in the five control subjects. A 'paradoxical' increase in plasma GH in response to TRH was observed in four of the seven patients with acromegaly. In these four patients plasma GHRH also increased in response to TRH. No TRH-induced increase in GHRH levels was observed in the other three patients with acromegaly who did not display an increase in GH in response to TRH. The present results imply that GHRH may be involved in the plasma GH response to TRH in patients with acromegaly.     

血管成形术后生长因子的基因表达

本实验在于观察血管成形术对生长因子基因表达的影响.本实验用球囊导管拉伤血管内膜和高脂饲养的方法建立兔髋动脉粥样硬化模型,再对模型兔进行球囊血管成形术.作者用Northern印迹同位素杂交和RT-PCR技术观察了血管成形术前后转移生长因子(TGF-β_1)、表皮生长因子受体(EGFR)和成纤维细胞生长因子碱性分子(bFGF)基因表达的情况.在血管成形术后1周和2周,TGF-β_1、EGFR和bFGF的mRNA表达较血管成形术前明显升高.血管成形术使兔髂动脉组织生长因子基因表达升高,可能与血管成形术后再狭窄有关.     

类胰岛素生长因子与肝癌

肝癌是常见的恶性肿瘤之一,其病程快且预后很差.其发生是一个多因素多步骤协同的复杂过程.近来的研究报道,肝癌发生分子机制与类胰岛素生长因子体系信号通路异常相关,类胰岛素生长因子是一种多功能细胞增殖调控因子,他在胚胎发育、中枢神经系统发育及肿瘤细胞增殖等方面具有重要的生物学功能.类胰岛素生长因子的生物学活性受到包括类胰岛素...