Validation of serum IGF-I as a biomarker to monitor the bioactivity of exogenous growth hormone agonists and antagonists in rabbits

The Effects of 20-kDa Human Placental GH in Male and Female GH-deficient Mice: An Improved Human GH?

A rare 20K isoform of GH-V (here abbreviated as GHv) was discovered in 1998. To date, only 1 research article has characterized this isoform in vivo, observing that GHv treatment in male high-fat fed rats had several GH-like activities, but unlike GH lacked diabetogenic and lactogenic activities and failed to increase IGF-1 or body length. Therefore, the current study was conducted to further characterize the in vivo activities of GHv in a separate species and in a GH-deficient model (GH-/- mice) and with both sexes represented. GHv-treated GH-/- mice had significant increases to serum IGF-1, femur length, body length, body weight, and lean body mass and reduced body fat mass similar to mice receiving GH treatment. GH treatment increased circulating insulin levels and impaired insulin sensitivity; in contrast, both measures were unchanged in GHv-treated mice. Since GHv lacks prolactin receptor (PRLR) binding activity, we tested the ability of GH and GHv to stimulate the proliferation of human cancer cell lines and found that GHv has a decreased proliferative response in cancers with high PRLR. Our findings demonstrate that GHv can stimulate insulin-like growth factor-1 and subsequent longitudinal body growth in GH-deficient mice similar to GH, but unlike GH, GHv promoted growth without inhibiting insulin action and without promoting the growth of PRLR-positive cancers in vitro. Thus, GHv may represent improvements to current GH therapies especially for individuals at risk for metabolic syndrome or PRLR-positive cancers.

Enhancement of The Stability of Human Growth Hormone by Using Tris(hydroxymethyl)aminomethane: Molecular Docking and Experimental Analysis

Objective

It is so difficult to formulate human growth hormone (hGH) in a solution with high stability and new drug delivery system (NDDs) due to physiochemical instability. The purpose of this study was to investigate the possibility of using Tris as a hGH stabilizer.

Materials and Methods

In this experimental study, the role of tris(hydroxymethyl)aminomethane (Tris) was evaluated as a hGH stabilizing agent in phosphate buffer, as a practical aqueous solution and a media to release NDDs. Highperformance liquid chromatography (HPLC) and enzyme-linked immune sorbent assay (ELISA) were applied to investigate the stability of hGH in solutions and dynamic light scattering (DLS) was used to measure the effect of Tris on the hydrodynamic size of hGH in aqueous solutions. Ultra violet (UV) spectrophotometry was used to check the hGH spectrum. In computational study, formation of ligand-protein complex of the Tris-hGH, and the intermolecular interactions between Tris and hGH were studied by molecular docking modeling.

Results

The results demonstrated that Tris at the optimum concentration, increases hGH stability in aqueous solutions. Also, molecular docking modeling confirmed that amino acid residues such as tyrosine (Tyr), proline (Pro), glutamic acid (Glu), aspartic acid (Asp), leucine (Leu), and phenylalanine (Phe) in hGH structure, were linked with Tris as a ligand.

Conclusion

It seems that interactions between hGH and Tris are the most important reason for increment of the physicochemical stability of hGH in aqueous solutions containing Tris.

Serum and seminal plasma IGF-1 associations with semen variables and effect of IGF-1 supplementation on semen freezing capacity in buffalo bulls

The objective of the study was to establish correlation of seminal and serum IGF-1 with seminal attributes, estimate antioxidant potential of IGF-1 by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays and to study the effect of IGF-1 supplementation on semen cryopreservation. For this study, buffalo bulls were divided into sub-fertile (n = 2) and normal (n = 5) on the basis of sperm mass motility and individual motility. The serum IGF-1 concentration of normal bulls was greater than in sub-fertile bulls, but there was no difference in the seminal IGF-1 concentration among the groups. The values from correlation analyses indicated that serum IGF-1 concentration is positively correlated with semen mass motility and sperm concentration. In the second experiment, IGF-1 did not have antioxidant activities when assessed with DPPH and FRAP assays. In the third experiment, the ejaculates of normal and sub-fertile bulls were cryopreserved using semen extender in which there was IGF-1 supplementation at 0 (control), 50, 100, 150, 200, 250, 350 and 450 ng/mL of extender. Supplementation of IGF-1 at 250 ng/ml resulted in improved sperm motility, longevity and membrane intactness as compared to control after cryopreservation of semen from normal buffalo bulls, but not sub-fertile bulls. In summary, serum IGF-1 concentration was correlated with sperm mass motility and concentration in buffalo bulls and supplementation of IGF-1 protected sperm during the cryopreservation process but effects were not due to direct antioxidant activity.

Characterization of igf1 and igf2 genes during maraena whitefish (Coregonus maraena) ontogeny and the effect of temperature on embryogenesis and igf expression

The insulin-like growth factors IGF-1 and IGF-2 play important roles in the growth, development, and metabolism of teleost fish. We isolated cDNA sequences of igf1, and igf2 genes from maraena whitefish. We quantified the mRNA and protein expressions of IGFs in different tissues of marketable juvenile maraena whitefish. Moreover, we analyzed the gene expression profiles during maraena whitefish development from unfertilized egg to fingerling and examined the effect of incubation temperature on igf1, and igf2 gene expression during embryonic and early larval development. Transcripts encoding IGF-1 or IGF-2 were detected in all tested tissues, with the greatest abundance in the liver. We measured higher igf2 than igf1 copy numbers in all tissues and at all developmental stages examined, even at advanced juvenile stages. Using the Western blot technique, we demonstrated that several isoforms of IGF-1 are expressed in the liver and gills but not in muscle tissue, indicating tissue-specific protein expression of IGF-1. We observed an accelerated embryonic development with increasing temperature, resulting in shortened hatching periods. Out of the three tested temperatures, we observed the highest hatching rate, larval hatching size, and larval growth at 6 °C. At 9 °C, hatching rate, larval hatching size and larval growth were reduced compared to the values we observed at 4 °C and 6 °C, since incubation temperature might have exceeded the optimum. To our knowledge, our data show for the first time that both igf1 and igf2 expression were upregulated due to elevated incubation temperature within embryonic development of fish. Further, we found significantly higher igf expression for the best-developing larvae (6 °C group) at specific life stages of maraena whitefish.

Control of (pre)-analytical aspects in immunoassay measurements of metabolic hormones in rodents

The measurement of circulating hormones by immunoassay remains a cornerstone in preclinical endocrine research. For scientists conducting and interpreting immunoassay measurements of rodent samples, the paramount aim usually is to obtain reliable and meaningful measurement data in order to draw conclusions on biological processes. However, the biological variability between samples is not the only variable affecting the readout of an immunoassay measurement and a considerable amount of unwanted or unintended variability can be quickly introduced during the pre-analytical and analytical phase. This review aims to increase the awareness for the factors 'pre-analytical' and 'analytical' variability particularly in the context of immunoassay measurement of circulating metabolic hormones in rodent samples. In addition, guidance is provided how to gain control over these variables and how to avoid common pitfalls associated with sample collection, processing, storage and measurement. Furthermore, recommendations are given on how to perform a basic validation of novel single and multiplex immunoassays for the measurement of metabolic hormones in rodents. Finally, practical examples from immunoassay measurements of plasma insulin in mice address the factors 'sampling site and inhalation anesthesia' as frequent sources of introducing an unwanted variability during the pre-analytical phase. The knowledge about the influence of both types of variability on the immunoassay measurement of circulating hormones as well as strategies to control these variables are crucial, on the one hand, for planning and realization of metabolic rodent studies and, on the other hand, for the generation and interpretation of meaningful immunoassay data from rodent samples.

Effects of Transport Duration and Environmental Conditions in Winter or Summer on the Concentrations of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Plasma of Market-Weight Pigs

In previous work using market-weight pigs, we had demonstrated that insulin-like growth factors (IGFs) and insulin-like growth factor binding proteins (IGFBPs) are regulated during shipment characterized by changing conditions of stress due to loading or unloading, transportation, lairage, and slaughter. In addition, we found in a previous study that IGFBP-2 concentrations were lower in pigs transported for longer periods of time. Therefore, we performed a more detailed study on the effects of transport duration and season on the plasma concentrations of IGFs and IGFBPs in adult pigs. For the study, exsanguination blood was collected from 240 market-weight barrows that were transported for 6, 12, or 18 h in January or July. IGF-I and -II were detected using commercial ELISAs whereas IGFBPs were quantified by quantitative Western ligand blotting. In addition, established markers of stress and metabolism were studied in the animals. The results show that plasma concentrations of IGFBP-3 were significantly reduced after 18 h of transport compared to shorter transport durations (6 and 12 h; p < 0.05). The concentrations of IGF-I in plasma were higher (p < 0.001) in pigs transported 12 h compared to shorter or longer durations. Season influenced plasma concentrations of IGFBP-3 and IGF-II (p < 0.05 and p < 0.01, respectively). Neither transport duration nor differential environmental conditions of winter or summer had an effect on glucocorticoids, albumin, triglycerides, or glucose concentrations (p > 0.05). However, low-density lipoprotein concentrations decreased after 18 h compared to 6 h of transport (p < 0.05), whereas high-density lipoprotein concentrations were higher (p < 0.05) in pigs transported for 12 or 18 h compared to those transported for only 6 h. Our findings indicate differential regulation of IGF-compounds in response to longer transport duration or seasonal changes and support current evidence of IGFs and IGFBPs as innovative animal-based indicators of psycho-social or metabolic stress in pigs.

Interference of stress with the somatotropic axis in pigs - lights on new biomarkers

The acceptance of animal products is increasingly associated with standardized animal welfare, which relates to appropriate animal husbandry from birth to slaughter. In particular, shipment to the slaughterhouse is considered as a critical process exposing the animals to a number of, in part severe, stressors. New biomarkers may be useful for the assessment of animal welfare. The IGF-system has been assessed in a commercial pig transport in conjunction with established markers of stress response. Furthermore, the effect of repeated restraint as an experimental model for repeated acute stress was investigated. During shipment from farm to slaughterhouse, plasma concentrations of IGFBP-3 and IGFBP-2 were significantly reduced (p < 0.01). After shipment, the plasma concentrations of IGFBP-5, glucocorticoids and IL-2 increased but decreased after lairage (p < 0.05) whereas IGF-1 decreased after shipment (p < 0.01). Repeated acute stress increased concentrations of IGFBP-3 and IGF-1 in exsanguination blood (p < 0.05). Differential IGF- signatures can indicate altered endocrine or metabolic control and thus contain complex animal-related information. The somatotropic axis may be of particular interest when established biomarkers such as cortisol, glucose, or lactate cannot be used for the assessment of animal stress or welfare.

Long-Acting C-Terminal Peptide-Modified hGH (MOD-4023): Results of a Safety and Dose-Finding Study in GHD Children

CONTEXT

Daily injections are required for growth hormone (GH) replacement therapy, which may cause low compliance as a result of inconvenience and distress in patients.

OBJECTIVE

C-terminal peptide-modified human GH (MOD-4023) is developed for once-a-week dosing regimen in GH-deficient (GHD) adults and children. The present trial was a safety and dose-finding study for weekly MOD-4023 in GHD children.

DESIGN

A multicenter, open-label, randomized, controlled phase 2 study in children with GHD, evaluating the safety, tolerability, pharmacokinetics/pharmacodynamics, and efficacy of three different weekly MOD-4023 doses, compared with daily recombinant human GH (r-hGH).

SETTING

The trial was conducted in 14 endocrinology centers in Europe.

PATIENTS

Fifty-three prepubertal children with GHD completed 12 months of treatment with either MOD-4023 (N = 42) or r-hGH (N = 11).

INTERVENTIONS

C-terminal peptide-modified hGH (MOD-4023) was administered weekly at a dose of either 0.25, 0.48, or 0.66 mg/kg/wk and compared with daily hGH at a dose of 0.24 mg/kg/wk.

RESULTS

MOD-4023 showed an estimated half-life approximately fivefold to 10-fold longer when compared with daily r-hGH. Insulin-like growth factor (IGF)-I and IGF-binding peptide 3 showed a dose-dependent increase during MOD-4023 treatment. IGF-I standard deviation score for MOD-4023 did not exceed +2. All MOD-4023 cohorts demonstrated adequate catch-up growth. The 0.66 mg/kg/wk dose demonstrated efficacy closest to daily r-hGH. No serious adverse events were observed during MOD-4023 treatment, and its tolerability was consistent with known properties of r-hGH.

CONCLUSIONS

This study confirms the long-acting properties of MOD-4023 and shows a promising safety and tolerability profile. This provides support for initiation of a phase 3 study in GHD children using a single weekly injection of MOD-4023.

A long-acting GH receptor antagonist through fusion to GH binding protein

Acromegaly is a human disease of growth hormone (GH) excess with considerable morbidity and increased mortality. Somatostatin analogues are first line medical treatment but the disease remains uncontrolled in up to 40% of patients. GH receptor (GHR) antagonist therapy is more effective but requires frequent high-dose injections. We have developed an alternative technology for generating a long acting potent GHR antagonist through translational fusion of a mutated GH linked to GH binding protein and tested three candidate molecules. All molecules had the amino acid change (G120R), creating a competitive GHR antagonist and we tested the hypothesis that an amino acid change in the GH binding domain (W104A) would increase biological activity. All were antagonists in bioassays. In rats all antagonists had terminal half-lives >20 hours. After subcutaneous administration in rabbits one variant displayed a terminal half-life of 40.5 hours. A single subcutaneous injection of the same variant in rabbits resulted in a 14% fall in IGF-I over 7 days.

IN CONCLUSION

we provide proof of concept that a fusion of GHR antagonist to its binding protein generates a long acting GHR antagonist and we confirmed that introducing the W104A amino acid change in the GH binding domain enhances antagonist activity.

Quantitative Western ligand blotting reveals common patterns and differential features of IGFBP-fingerprints in domestic ruminant breeds and species

The insulin-like growth factor binding proteins (IGFBPs) are determinants of local IGF-effects and thus have an impact on growth and metabolism in vertebrate species. In farm animals, IGFBPs are associated with traits such as growth rate, body composition, milk production, or fertility. It may be assumed, that selective breeding and characteristic phenotypes of breeds are related to differential expression of IGFBPs. Therefore, the aim of the present study was to investigate the effects of selective breeding on blood IGFBP concentrations of farm animals. Breeds of the sheep, goat, and cattle species were investigated. IGFBP-3, -2, and -4 were analyzed with quantitative Western ligand blotting (qWLB), enabling comprehensive monitoring of intact IGFBPs with IGF-binding capacity. We show that in sera of all species and breeds investigated, IGFBP-3, -2, and -4 were simultaneously detectable by qWLB analysis. IGFBP-3 and the total amount of IGFBPs were significantly increased (P<0.05) in Cameroon sheep, if compared to 3 of 4 other sheep breeds, as well as in Dwarf goats versus Toggenburg and Boer goats (P<0.01). IGFBP-2 was elevated in Cameroon sheep and Boer goats, if compared to other breeds of these species (P<0.01), respectively. Holstein Friesian dairy cows had higher levels of IGFBP-4 (P<0.05), if compared to conventional crossbreeds of beef cattle. In Dwarf goats the ratio of IGFBP-3/IGFBP-2 was about 3-fold higher than in other goat breeds (P<0.001). The total IGFBP amount of Toggenburg goats was reduced (P<0.05), compared to the other goat breeds. In conclusion, our data indicate that common and specific features of IGFBP fingerprints are found in different ruminant species and breeds. Our findings may introduce quantitative Western ligand blotting as an attractive tool for biomarker development and molecular phenotyping in farm animal breeds.

The biochemistry of blister fluid from pediatric burn injuries: proteomics and metabolomics aspects

Burn injury is a prevalent and traumatic event for pediatric patients. At present, the diagnosis of burn injury severity is subjective and lacks a clinically relevant quantitative measure. This is due in part to a lack of knowledge surrounding the biochemistry of burn injuries and that of blister fluid. A more complete understanding of the blister fluid biochemistry may open new avenues for diagnostic and prognostic development. Burn insult induces a highly complex network of signaling processes and numerous changes within various biochemical systems, which can ultimately be examined using proteome and metabolome measurements. This review reports on the current understanding of burn wound biochemistry and outlines a technical approach for 'omics' profiling of blister fluid from burn wounds of differing severity.

Growth hormone binding protein - physiological and analytical aspects

A significant proportion of total circulating growth hormone (GH) is bound to a high affinity growth hormone binding protein (GHBP). Several low affinity binding proteins have also been described. Significant differences between species exist with respect to origin and regulation of GHBP, but generally it resembles the extracellular domain of the GH receptor. Concentrations are associated with GH status, body composition and other factors. Although the clinical relevance of GHBP is not fully understood it is suggested that concentrations indirectly reflect GH receptor status. This is supported by cases of Laron's syndrome where a molecular defect in the extracellular domain of the GH receptor is associated with low or unmeasurable GHBP concentrations. Methods to measure GHBP have evolved from chromatographic, activity based procedures to direct immunoassays. In clinical practice, measurement of GHBP can be helpful to differentiate between GH deficiency and GH insensitivity, particularly if GHBP is absent.