The insulin-like growth factors constitute a family of peptides which have structural homology with proinsulin, and which possess broad anabolic and mitogenic action in wide variety of tissues. The two main forms of IGFs in serum of adults are insulin-like growth factor I (IGFI) and insulin-like growth factor II (IGFII). IGFI appears to be the major growth factor involved in postnatal growth and is believed to mediate most (if not all) of the growth promoting effects of growth hormone (GH). IGFII may be involved in embryonic and fetal growth. It is the aim of this article to present an account of recent advances in the understanding of the origins, functions, and clinical significance of these peptides. Particularly the role of IGFs in fetal growth during normal and diabetic pregnancies.

The solution structures of the homologous growth factors hEGF and hTGF-alpha, have been determined independently from high resolution nuclear magnetic resonance (NMR) data. A model of the insulin-like growth factor structure based on insulin coordinates (Blundell et al. (1978) Proc natn. Acad. Sci. U.S.A. 75, 180-184), has also been refined using molecular dynamics simulations with NMR-determined restraints. Knowledge of these structures, together with known sequences of other homologous proteins and experiments with site-specific residue changes, allows predictions to be made about growth factor residues which might be involved in the receptor-ligand interfaces.

IGFI signaling pathway is sufficient to regulate myofibre hypertrophy postnatally, which is associated with muscle mass in economically livestock. In the present study, we drafted the developmental expression pattern of eight genes implicated in IGFI system across six stages of postnatal myofibre growth in Yorkshire and Tongcheng pigs. The results indicated that GRB2 may contribute to increased DNA content in postnatal myofibre hypertrophy via GRB2-Ras-Raf-MEK-ERK sub-pathway; INSR, PDK1, IRS1 and eIF4E may contribute to high growth rate via stimulating the rate of protein synthesis and inhibiting the rate of protein degradation. In addition, the results suggested 60 days maybe a very important stage in postnatal myofibre growth. Moreover, higher mRNA level of IRS1 and GLUT4 maybe associated with inferior meat quality in Yorkshire compared to Tongcheng pig. Therefore, IGFI signaling pathway regulates myofibre hypertrophy postnatally via complicated signal effectors, which may have negative impact on meat quality simultaneously.

OBJECTIVE

To investigate the mechanism of growth hormone insensitivity of rats under the endotoxemic condition.

METHODS

Sprague Dawley rats (n = 180) were injected endotoxin, TNF-alpha, and IL-6 respectively. Part of endotoxin injected rats were treated with exogenous somatotropin simultaneously, and all rats were killed at different time points. Liver expression of IGF I, GHR and SOCS-3 mRNA was detected by RT-PCR, the levels of growth hormone (GH) were measured by radioimmunoassay, and the levels of TNF-alpha and IL-6 were detected by ELISA.

RESULTS

Serum GH levels showed no significant change after endotoxin injection; however, liver IGF I and GHR mRNA expressions were obviously down-regulated in endotoxemic rats, with the lowest decrease of 53% and 89% respectively. Although SOCS-3 mRNA was weakly expressed in control rats, it was strongly up-regulated in endotoxemic rats and the marked increase was 7.84 folds. The higher LPS dosage induced marked GHR mRNA down-regulation and marked SOCS-3 mRNA up-regulation. Exogenous GH made IGFI mRNA expression increase 25% in the control rats, but it did fail to prevent the decline in IGFI mRNA expression in endotoxemic rats. Endotoxin stimulated the production of TNF-alpha and IL-6, and the elevated IL-6 levels showed a positive correlation with increased SOCS-3 mRNA expression. Liver GHR mRNA expression was obviously down-regulated after TNF-alpha i.v. injection, but for IL-6, it mainly up-regulated the liver SOCS-3 mRNA expression.

CONCLUSIONS

The growth hormone insensitivity could be induced by LPS injection, which might be associated with down-regulated GHR mRNA expression and up-regulated SOCS-3 mRNA expression. The in vivo biological activities of LPS may be partially mediated by TNF-alpha and IL-6 at different aspects.

The insulin-like growth factor (IGF) system plays a pivotal role in the regulation of growth, and IGF binding proteins (IGFBPs) are important regulatory factors in the IGF system. Generally, IGFBPs inhibit IGF actions by preventing its binding to receptors. Under some conditions, the IGFBPs can also enhance IGF actions. IGFBP1 is generally inhibitory to IGFI. In this study, the grouper (Epinephelus coioides) igfbp1 (MK621003) gene was cloned from the liver. The sequence of igfbp1 cDNA was 1055 bp and contained a 5'UTR of 127 bp and a 3'UTR of 247 bp, and the ORF of grouper igfbp1 was 741 bp, encoding 246 amino acids. The tissue distribution results showed that igfbp1 has a higher expression in the liver. In the nutritional status experiment, igfbp1 expression was significantly increased in the liver after 7 days of fasting and was markedly decreased after refeeding. In in vitro experiments, igfbp1 expression in grouper primary hepatocytes was significantly inhibited by recombinant grouper Gh (growth hormone) in a dose-dependent manner. Additionally, igfbp1 expression decreased in grouper primary hepatocytes upon incubation with insulin. This is the first report describing grouper igfbp1, and these findings contribute to understanding the roles of IGFBP1 in metabolism and growth in grouper.

Objective: Insulin-like growth factor 1 (IGFI) is one of several growth factors which is induced by growth hormone (GH), which activates the Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) pathway, and plays crucial roles in normal human growth, metabolism, and systemic energy homeostasis. However, little is known about the negative regulation of IGF-I production under different physiological or pathological conditions. Herein, we explore whether activation of endoplasmic reticulum (ER) stress regulates IGF-I production and normal body growth.

Materials and methods: C57BL/6 J mice were challenged with tunicamycin (Tm) to induce ER stress activation. 24 h after stimulation, hepatic mRNA expression was analyzed by RNA-Seq and validated by qPCR. Enzyme-linked immunosorbent assay (ELISA) was performed 24 h after Tm stimulation. Body growth was determined 16 days after Tm stimulation. Animals were then sacrificed and liver tissues were collected for further analysis.

Results: Mice challenged with Tm displayed a retardation of growth. Molecularly, we found that ER stress inhibited phosphorylation of STAT5. IGF-I transcription and circulating IGF-I were also dramatically decreased under ER stress activation. Moreover, our results demonstrate that IGF-I administration ameliorates Tm-induced growth retardation.

Conclusions: ER stress induces growth retardation. ER stress inhibits hepatic GH-JAK2 signaling activation and its downstream target gene expression. These results warrant further research to explore the crosstalk between ER stress and growth hormone signaling in improving body growth.

Keywords: Body growth; ER stress; IGF-I.

Defects in the growth hormone (GH)-insulin-like growth factor (IGF)I axis may cause GH resistance characterized by IGFI deficiency and growth failure. The range of defects causing GH resistance is broad as are their biochemical and phenotypical characteristics. We propose that GH-IGFI axis defects form a continuum of clinical and biochemical effects ranging from GH deficiency to GH resistance. The pathophysiology of GH resistance is described followed by a scheme for investigation of the child with severe short stature and normal GH secretion. We critically discuss GH therapy for such patients and define acceptable growth responsiveness. Finally we discuss therapy with IGF-I within the limits of the USA Food and Drug Administration and European Medicines Agency labels for GH resistance.

The paper deals with a study of growth factors in blood serum from patients with locally-advanced and metastatic cancer of prostate prior to treatment. Twelve months after diagnosis was made, the data were compared with the initial indices. Immunoenzymatic assay was used in combination with the existing standard procedures of examination of cancer patients. Data were compared with clinico-morphological and serologic evidence on tumor process using medico-biological statistics.

We have established a hepatocarcinoma cell line (LFCl2A) that produces voluminous tumors when injected into syngeneic Commentary rats. We have previously shown that when these cells were transfected with an episomal vector expressing the antisense IGFI cDNA the transduced cells partly lost their tumorigenic properties and were able to induce the regression of established hepatocarcinoma in syngeneic animals. In this paper, our aim was to determine if one could substitute the use of episomal expression vector by constructing a recombinant adenoviral vector that should be, in theory, easier to supply to humans. We have shown that, in vitro, the cells transfected as well as those infected have lost their tumorigenic properties, but in vivo the infected cells (which are no more tumorigenics) are not able to prevent tumor development.

BACKGROUND

Growth hormone (GH) secretion is increased in pre-pubertal children with type 1 diabetes and GH excess produces insulin resistance. Early-morning insulinopenia contributes to lower insulin-like growth factor (IGF-I) levels and to GH hypersecretion.

OBJECTIVE

To evaluate differences in GH/IGF-I axis of pre-pubertal children with type 1 diabetes treated with glargine or detemir as long-acting insulin analogues, which was the main outcome measure, and to compare insulin effects in obtaining good metabolic control.

METHODS

Children with type 1 diabetes.

METHODS

This was a 32-week, randomized, open-label, two-period, cross-over comparison between bedtime glargine and twice-daily detemir insulin, involving pre-pubertal children in care at a diabetes pediatric centre. After a 8-week-run-in period subjects were randomized to bedtime glargine or twice-daily detemir insulin administration. After a 12-week period treatments were inverted and continued for additional 12 weeks.

RESULTS

Overall, 15 pre-pubertal children (53.3% males, mean age 8.6±1.5 years, duration of diabetes 4.2±1.5 years) completed the study. Groups did not differ for GH/IGF axis and HbA1c levels. Treatment with glargine was associated with lower fasting glucose values than treatment with detemir (8.1±1.5 vs. 8.2±1.7 mmol/L, p=0.01). Incidence rate of hypoglycemia was not different between insulin treatments (IRR=1.18, 95%CI 1.00-1.38; p=0.07). Detemir treatment was associated with a higher increase in body weight (p=0.008) and height (p=0.02) when compared with glargine.

CONCLUSIONS

Detemir and glargine not show significant differential effects on the GH/IGFI axis. The greater weight gain and height associated with detemir treatment, apparently not related to the level of pubertal growth, deserve further investigation.

Developmental changes in hepatic growth hormone binding sites were examined in the genetically obese male fa/fa rats and in the lean littermates. At 16 days, fa/fa pups are normoinsulinemic; the specific binding of 125I-hGH to liver membranes is comparable in the two genotypes. At 4 weeks and later on, plasma membranes and Golgi fractions of male obese Zucker rats have more GH binding sites than lean littermates. The GH pituitary content is comparable in the two genotypes from 2 to 8 weeks and in 14-week-old fa/fa rats it is half that in lean animals. In the two genotypes plasma IGFI dramatically increases during puberty. At 4 weeks, plasma IGFI level is significantly higher in fa/fa rats than in lean littermates. In this model of genetic obesity, an increased GH binding to liver membranes is observed after the third week of life, shortly after the onset of hyperinsulinemia in the fa/fa rat.

Background: A common growth hormone receptor polymorphism with deletion of exon 3 (d3-GHR) has previously been linked to increased postnatal growth on the one hand and decreased fetal growth on the other. Regulation of fetal growth is positively dependent on secretion of placental GH (hGH-V).

Objective: We explored the effect of the fetal d3-GHR genotype on maternal serum levels of hGH-V and fetal growth. The cellular localization of hGH-V synthesis and the GH receptors were determined in normal placentas.

Methods: 43 healthy mother-child pairs were examined during pregnancy with measurements of hGH-V during third trimester, and serial ultrasound measurements determined fetal growth rate. Birth anthropometrics were obtained. The GHR genotype of the child was analysed postnatally. Immunohistochemical (IHC) analysis was conducted on four placentas.

Results: The presence of the d3-GHR genotype was associated with a markedly reduced concentration of hGH-V in maternal serum (β -0.52, SE 0.24, p = 0.04) compared to those who had a fl/fl genotype. Accordingly, a tendency towards reduced fetal growth rate during third trimester (β -25.8, SE 12.7, p = 0.05) and a lower birth weight were found among carriers of the d3-GHR allele, but these associations did not reach statistical significance (p = 0.08). IHC analysis showed expression of placental GH and GHR in the villous syncytiotrophoblast, the extravillous trophoblast, and the decidual cells and smooth muscle cells in chorionic vessels.

Conclusions: The presence of the d3-GHR polymorphism in the fetus was associated with lower maternal serum levels of hGH-V, decreased fetal growth rate in third trimester and lower birth weight compared to the wildtype.

Keywords: Fetal growth; Insulin-like growth factor-I (IGFI); Placental growth hormone (hGH-V).

The insulin-like growth factor 1 receptor (IGF1R) is a key factor in intrauterine and postnatal growth by mediating the biological function of IGF-I. Mutations of IGF1R gene are usually associated with growth retardation, but the clinical picture of IGF1R mutation carriers is heterogeneous. Indeed, these patients show clinical signs compatible with Silver-Russell syndrome (SRS), and some IGF1R mutation carriers have been identified in SRS cohorts. We therefore investigated deoxyribonucleic acid samples of 19 growth-retarded patients with SRS features. Apart from 8 non-pathogenic variants, we detected heterozygosity for the unknown duplication, c.1056_1057dup, leading to a premature termination in one patient and his growth retarded sister. Due to its nature, we assumed that this variant is probably pathogenic. However, the patient and his sister exhibited spontaneous catch-up growth in later life. We therefore hypothesize that the c.1056_1057dup does not result in a significant disruption to the GH-IGFI axis. Thus, this IGF1R mutation without obvious clinical consequence might challenge the actual concept of IGF1R haploinsufficiency as a general cause for disturbed growth in IGF1R mutation carriers. In the future, mutation analysis of IGF1R should be considered in growth-retarded patients with microcephaly and minor SRS features, but not in probands with the characteristic SRS phenotype including macrocephaly.

We characterised IGFI and IGFII receptors and located them in bovine muscle during foetal growth. Semitendinosus muscle samples were taken from foetuses ranging from 80 to 270 days post-conception. The relative affinities of 125I-IGFII and 125I-IGFI mark the presence of typical type II and type I receptors in foetal muscle membranes. IGFII-specific binding is consistently five times greater than that of IGFI. The patterns of 125I-IGFII- and 125I-IGFI-specific binding are similar. They increase up to 110 and 170 days post-conception, respectively (P < 0.05); thereafter, they decrease (P < 0.05). This decrease was due to a fall in the number of receptors without any change in affinity. At the adult stage the specific binding of both the 125I-IGF is very low. In foetal muscle, type II receptors are located both in the muscle bundles and in the connective tissue while type I receptors are only located in the muscle bundles.

Chromium (Cr) has been reported to enhance immune function and improve insulin sensitivity and performance in beef and dairy cattle. However, its effect on bovine macrophage inflammatory and metabolic response is unknown. The objective of this study was to characterize the effect of dietary Cr on the inflammatory and metabolic response of polarized macrophages ex vivo. Twelve primiparous and 16 multiparous healthy Holstein cows in mid lactation (143 ± 37 d in milk) were enrolled in this study. Cows were fed a common total mixed ration once per day that was top-dressed with 200 g of ground corn containing 1 of 2 dietary treatments: control (CTL, no Cr supplementation) or Cr propionate (CrP, 8 mg of Cr/cow per day) for 35 d. At d 1, 17, and 35 of treatment, blood monocytes were isolated and cultured to obtain 3 monocyte-derived macrophage (MDM) phenotypes: M0 (non-polarized), M1 (pro-inflammatory; IFN-γ polarized) and M2 (anti-inflammatory; IL-4 polarized). The experiment was set in a randomized complete block design. Neither dry matter intake nor milk yield was affected by treatment. Plasma concentrations of metabolites and the metabolic and inflammatory response of MDM in spent media were not affected by treatment. Neither the whole blood cell population nor the specific proportion of leukocytes was affected by the main effect of treatment. However, we did observe a trend for fewer circulating neutrophils in cows fed CrP than in cows fed CTL for 35 d, which may be partly attributable to a greater influx of neutrophils into peripheral tissues, a reduced pro-inflammatory response during disease, or both; this warrants future study. Expression of IGFI was increased in MDM-M0, and expression of CXCL11 tended to increase in MDM-M2 from cows fed CrP compared with cows fed CTL. Expression of SLC2A3 also tended to increase in MDM-M2 from cows fed CrP compared with cows fed CTL at 17 d. Our results suggest that CrP has minimal effect on the inflammatory and metabolic response of MDM for Holstein dairy cows in mid lactation. Future studies are warranted to evaluate the differential regulation of Cr on the inflammatory and metabolic response of leukocytes from dairy cows at different stages of lactation and parity.

The aim of the present study was to examine the effects of insulin on glucose uptake and glycogen synthesis in crab Chasmagnathus granulata gills. We observed an increased glucose uptake and incorporation of d-[(14)C]glucose into glycogen when posterior C. granulata gills were incubated in the presence of insulin; however, this was not observed in anterior gills, despite the presence of similar insulin receptors. In posterior gills, basal glucose uptake in the summer was significantly higher than in the winter. Moreover, in the summer, the insulin dose required to stimulate glucose uptake was twice as high as in the winter. However, there was no significant difference in terms of basal glycogen synthesis in summer and winter. In crustaceans, the endogenous insulin/IGFI substance might be involved in the rapid restoration of glycogen levels in the gills, increasing glucose uptake and glycogen synthesis. Bovine insulin seems to have a stimulatory effect on glycogen metabolism only in posterior gills.

Growth hormone (GH) insensitivity is associated with several different mutations of the GH receptor gene and a recently described new genetic disorder of the IFGI gene. The phenotype and biochemical characteristics were studied in 82 patients with growth hormone insensitivity, from 23 different countries, with a mean age of 8.25 years. Mean height SDS was -6.09. SDS of the IGF binding protein -3 (IGF BP3) was 7.99. Twenty three per cent of the patients were GH binding protein (GHBP) positive >> 10%). Mean height SDS score was -6.5 in the GHBP negative patients and -4.9 in the GHBP positive patients (p < 0.001). Fifteen different mutations of the GH receptor gene were identified in 27 patients. There were no relationships between the type of mutation or the involved GH receptor gene exon and height or IGFBP-3 SDS. The new phenotype due to a partial deletion of the IGFI gene was described in a 15-year-old boy who presented with a severe intrauterine growth retardation, a very poor postnatal statural growth, a neurosensorial deafness and a mild mental retardation. He had elevated GH levels, normal levels of IGFBP3, undetectable levels of IGFI, and showed no response to GH treatment. A partial deletion concerning the exons 4 and 5 of the IGFI gene was found. Thus, GH insensitivity is associated with large variations in the clinical and biochemical phenotypes.

Pleomorphic adenoma is a slow-growing salivary gland tumor frequently arising from the parotid gland. In this study, we investigated the role of the insulin-like growth factor I-II receptor (IGFI-IIR) levels on the development of parotid gland pleomorphic adenomas. The study included 20 males and 20 females who had superficial parotidectomy with a histopathological diagnosis of pleomorphic adenoma in Fırat University Otorhinolaryngology Clinic between 2000 and 2011. The ages of the patients ranged between 20 and 50 years. The control tissues were obtained unilaterally from the parotid glands of five female and five male cadavers during autopsy, and consisted of 0.5 × 0.5 cm sized normal parotid gland tissues. The expression of IGFI-IIR were measured in both tumor and tumor-free normal parotid tissue in the study group while only the normal parotid tissues were studied in the cadavers. Primary polyclonal antibodies against IGFI-IIR were used with "Streptavidin-Biotin Complex" method for immunohistochemical staining of both the study and the control groups' tissue sections. In this study, the IGFI-IIR levels were found significantly higher in the pleomorphic adenoma tissue (p < 0.05). In addition, IGFI-IIR expression was greater in normal parotid tissues of the study group when compared to the normal parotid tissues of the cadavers. However, the difference was not statistically significant (p>> 0.017). Greater expression for IGFI-IIR in pleomorphic adenoma when compared to normal parotid tissues of the patients and the cadavers suggests that IGFI-II may be important factors in the development of pleomorphic adenoma.

Many sex differences in liver gene expression originate in the brain, depend on GH secretion and may underlie sex disparities in hepatic disease. Because epigenetic mechanisms may contribute, we studied promoter methylation and microRNA abundance in the liver, associated with expression of sexual dimorphic genes in mice with selective disruption of the dopamine D2 receptor in neurons (neuroDrd2KO), which decreases hypothalamic Ghrh, pituitary GH, and serum IGFI; and in neonatally androgenized female mice which have increased pituitary GH content and serum IGFI. We evaluated mRNA levels of the female predominant genes prolactin receptor (Prlr), alcohol dehydrogenase 1 (Adh1), Cyp2a4, hepatocyte nuclear transcription factor 6 (Hnf6), and the male predominant gene, Cyp7b1. Female predominant genes had higher mRNA levels compared to males, but lower methylation was only detected in the Prlr and Cyp2a4 female promoters. In neuroDrd2KO mice sexual dimorphism was lost for all genes; the upregulation (feminization) of Prlr and Cyp2a4 in males correlated with decreased methylation of their promoters, and the downregulation (masculinization) of Hnf-6 mRNA in females correlated inversely with its promoter methylation. Neonatal androgenization of females evoked a loss of sexual dimorphism only for the female predominant Hnf6, and Adh1 genes, but no differences in promoter methylation were found. Finally, mmu-miR-155-5p, predicted to target Cyp7b1 expression, was lower in males in association with higher Cyp7b1 mRNA levels compared to females, and was not modified in neuroDrd2KO or TP mice. Our results suggest specific regulation of gene sexually dimorphic expression in the liver by methylation or miRNAs.

An original method for the culture of granulosa and thecal cells of the domestic hen was developed and used to investigate the effects of serum, of EGF and of IGFI on the multiplication of these cell types and on their secretion of steroid hormones. The growth of the cultures (measured by the accumulation of DNA in the culture wells) over a 72 hour period was judged to be satisfactory although slower without serum. Both growth factors stimulated cell growth and EGF inhibited steroidogenesis in both cell types. IGFI inhibits the secretion of oestrogens by thecal cells but it stimulates the secretion of progesterone by granulosa cells towards the end of the period of culture.

The chimeric molecules of "Insulin-Insulin-like Growth Factor-I", Ins/IGFI(8) and Ins/IGF-I(11) were obtained by means of enzymatic semisynthesis. The growth promoting activity of these chimeric molecules were evaluated with a mouse mammary tumor derived cell line, GR2H6, and compared with that of IGF-I, insulin and desoctapeptide insulin (DOI). Both compounds have lower activities than IGF-I and effects similar to insulin, but are more potent mitogens than DOI. These results indicate that the C-terminus of insulin B-chain is importantly involved in its growth promoting activities.

The objective of the present study was to investigate the dynamic change of serum parameters and milk composition by dietary FA supplementation with ewes with different litter size from mating to lambing. The ewes were divided into six treatments (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) according to dietary FA levels (control, CON; 16 or 32 mg·kg^-1 rumen-protect-FA supplementation, F16 and F32) and litter size (twin born, TW; and triplet born, TR). In serum, the concentration of folate increased linearly with dietary FA supplementation (P < 0.05), regardless of the litter size, they showed a quadratic response to gestation progression (P < 0.05). With dietary FA addition, IGFI-I levels significant increased from late gestation to after lambing (P < 0.05), and linearly increased immunoglobulin during the perinatal period (P < 0.05). In colostrum and milk at d 15, the content of folate, lactoferrin, and IgG were affected positively by FA supplementation (P < 0.05). IgG was higher in the TW group than TR in colostrum (P < 0.05), and lactoferrin in TW was lower than TR in milk of d 15 (P < 0.05). FA supplementation increased protein content in colostrum (P < 0.05), while it had no effect on the fat, lactose, and BUN of colostrum and milk of d 15 (P > 0.05). These results suggest that FA supplementation during gestation could regulate maternal blood metabolism and contribute to milk immune composition.

BACKGROUND

Growth hormone (GH) treatment currently requires years of treatment. Maintaining full compliance with daily injections has been difficult. Teens have the highest rate of non-concordance (missing injections 1-2 per week). In adults the rate of low concordance (low IGFI) rises with each year of treatment. Improving compliance to GH therapy by less burdensome means of GH replacement can be achieved either by changing GH delivery frequency (weekly, monthly) or by changing injection device characteristics (minimal preparation, easy setting, minimal pain, automatic needle insertion, needle free devices). LONG ACTING FORMULATIONS: Long-acting forms of GH have been developed either as sustained-release preparations of GH (Nutropin-depot, which has been withdrawn in 2004 and LB 03002 once weekly GH, which has received a positive opinion by CHMP of EMA in early 2013) or as the conjugated analogues which prolong the half life of GH. Currently a variety of modified GH molecules which delay GH clearance (CTP modified GH, recombinant polypeptide XTEN, GH conjugated with albumin, GH linked to immunoglobulin) are studied and the ongoing studies are in different phases (from I-III). Each of these preparations has been tested in experimental animal models. EFFICACY AND SAFETY: Although different types of formulations have been studied, all are pharmacokinetically and pharmacodynamically effective in extending GH action and result in prolonged increase in IGF-I concentrations. Clinical data are available for once-weekly sustained-release GH treatment and the data show beneficial effects in adults with GH deficiency over a 12 month period and adequate growth rate in pre-pubertal children with GH deficiency over the period of three-years.

CONCLUSIONS

Clinical data are still very limited. Available short-term studies show that treatment with long-acting GH preparation is effective and safe in GH deficient children and adults. A different physiology underlies the long-acting GH and we still need to improve our knowledge about these formulations of GH. Long-term studies are needed to confirm the value and safety (greater exposure to GH) of these agents.

In this study an exons-connecting technique was used to amplify the complete DNA sequence encoding the mature peptide of IGF-I. Two pairs of primers were synthesized, primer a (Pa) and primer b (Pb) were used to amplify exon 2 coding fragment while primer c (Pc) and primer d (Pd) for amplifying exon 3 coding fragment. Pb was 40 bp, 18 bp at its 5' end was same with the anti-sense of exon 3's 5' end. Pc consisted of 41 bp with 22 bp at its 5' end consistent with the sense of the exon 2's 3' end. Genome DNA was extracted from rat liver. Using rat genome DNA as template PCR was performed with Pa, Pb and Pc, Pd as primers respectively. Two kinds of PCR products were obtained. One was 90 bp corresponding with the exon 2, another was 160 bp corresponding with the exon 3. Another PCR was done with these two PCR products used as not only template but also primers for each other. A 210 bp DNA fragment was produced, which encodes the mature peptide of rat IGF-I. Firstly the gene was cloned into plasmid pUC18. Then the recombinant plasmid pUC-IGF-I was digested with restriction endonuclease BamHI and EcoRI, plasmid pGEX-3X was digested with the same enzyme. IGF-I gene was linked into pGEX-3X and expressing plasmid pGEX-IGF-I was constructed. Plasmid pGEX-IGF-I was transformed into E. coli DH5 alpha and induced to express by IPTG. Expressed protein was analysized by SDS-PAGE. A fusion protein of GST-IGFI about 32.5 kDa could be observed. Western blot was performed with goat anti-human IGF-I IgG as primary antibody and donkey anti-goat IgG HRP as secondary antibody. Its result confirmed that the fusion protein really containing IGF-I. GST-IGFI was purified by affinity-chromatography and carrier-protein GST was cut off by Factor Xa. The bioactivity of purified IGF-I was detected with cultured NIH3T3 cell. The recombinant rat IGF-I can promote cell proliferation, shown by the elevation of 3H-TdR incorporation.