Somatomedins (Total 26170 Papers Found)

For several years, it has been well accepted that insulin-like growth factor 1 (IGF-1) plays a critical role in peripubertal growth. Recently, we have provided evidence to suggest that this peptide may also be involved in the sexual maturation process, via an action to stimulate hypothalamic luteinizing hormone releasing hormone release. Because ethanol (ETOH) delays puberty, an event that is associated with depressed growth rates and decreased growth hormone and luteinizing hormone (LH) secreti ...
CONTEXT Factors involved in the biology of normal and cancer stem/precursor cells from the thyroid are unknown. Thyroid cancer cells are responsive to insulin and IGF-I and IGF-II and often overexpress the insulin receptor (IR) and the IGF-I receptor (IGF-IR). OBJECTIVE We investigated the role of IR isoforms (IR-A and IR-B), IGF-IR, and their ligands in thyroid follicular cell precursors both normal and malignant. DESIGN We established cultures of follicular cell precursors as thyrospheres ...
We determined the genetic contribution of 18 anthropometric and metabolic risk factors of type 2 diabetes using a young healthy twin population. Traits were measured in 240 monozygotic (MZ) and 138 dizygotic (DZ) twin pairs aged 18 to 34 years. Twins were recruited from the Belgian population-based East Flanders Prospective Twin Survey, which is characterised by its accurate zygosity determination and extensive collection of perinatal and placental data, including information on chorionicity. H ...
Osteoporosis is a growing health problem in women and in men. This cross-sectional study examined the association of anthropometric, lifestyle, and hormonal factors with bone mineral density (BMD) in 152 healthy Korean middle-aged men. Smoking habits and alcohol consumption were assessed by interview. Serum testosterone and insulin-like growth factor-I (IGF-I) levels were measured by radioimmunoassay, and serum growth hormone (GH) levels were measured by immunoradiometric assay. GH stimulation t ...
OBJECTIVES The IGF-II gene has four promoters (P1-P4); each initiates promoter-specific transcription. Studies have shown that IGF-II promoters normally active during fetal growth, but silent in postnatal life, are reactivated in cancer. In a previous study, we found IGF-II transcription evaluated at a common translated region was associated with ovarian cancer progression. This study was conducted to further determine which IGF-II promoters were responsible for the association. METHODS Promot ...
We examined the possible role of insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-Ir) during multistage carcinogenesis in mouse skin. For this purpose, the expression of both IGF-I and IGF-Ir was investigated in mouse skin during tumor promoter treatment and in primary papillomas and squamous cell carcinomas (SCCs) obtained from SENCAR mice treated with standard initiation-promotion regimens. IGF-I transcripts were not detectable or only weakly detectable in normal SENCAR mouse epide ...
OBJECTIVE To evaluate the possible biochemical effect of diet and heredity on the rates of monozygotic and dizygotic twinning. STUDY DESIGN In that insulin-like growth factor (IGF) has been found to be elevated in cows selected for their demonstrated increased twinning rate, the effect of agents that influence the level of IGF in women was examined. This was correlated with their prior history of singleton versus twin birthing. In particular, the effect of diets consisting of or excluding anim ...
The aim of the present study was to investigate, in human lung cancer, the relationship between weight loss and the existence of a low body cell mass (BCM) on the one hand, and the putative presence of systemic inflammation, an increased acute-phase response, anorexia, hypermetabolism and changes in circulating levels of several anabolic and catabolic hormones on the other. In 20 male lung cancer patients, pre-stratified by weight loss of >/=10% (n=10) or of <10% (n=10), the following meas ...
OBJECTIVE Short-term growth hormone (GH) treatment normalises body fluid distribution in adult GH deficient patients, but the impact of long-term treatment on body fluid homeostasis has hitherto not been thoroughly examined in placebo controlled trials. To investigate if the water retaining effect of GH persists for a longer time we examined the impact of 4 months GH treatment on extracellular volume (ECV) and plasma volume (PV) in GH deficient adults. DESIGN Twenty-four (18 male, 6 female) ad ...
Ghrelin, an acylated 28-amino acid polypeptide, was primary isolated from the stomach, and the stomach is a main source of circulating ghrelin. Ghrelin strongly and dose-dependently stimulates release of growth hormone from the anterior pituitary, as well as increases food intake and fat deposition. Previous studies showed that ghrelin exhibits protective and therapeutic effect in different parts of the gastrointestinal system, including the oral cavity. The aim of present study was to examine t ...
An indolent non-healing wound and insulin and/or insulin-like growth factor (IGF1) resistance are cardinal features of diabetes, inflammation and hypercortisolemia. Little is known about why these phenomena occur in so many contexts. Do the various triggers that induce insulin and/or IGF1 resistance and retard wound healing act through a common mechanism? Cultured dermal fibroblasts from rats and full-thickness excisional wounds were used as models to test the premise that reactive oxygen specie ...
IGF-binding protein (IGFBP)-3 is produced by cultured porcine embryonic myogenic cell (PEMC) cultures and is secreted into the medium. Levels of secreted IGFBP-3 and IGFBP-3 mRNA are significantly reduced during differentiation and increase after differentiation is complete, suggesting that IGFBP-3 may play some role in myogenesis and/or in changes in myogenic cell proliferation that accompany differentiation. IGFBP-3 reportedly may either suppress or stimulate proliferation of cultured cells de ...
Lifespan regulation by mitochondrial proteins has been well described, however, the mechanism of this regulation is not fully understood. Amongst the mitochondrial proteins profoundly affecting ageing are prohibitins (PHB-1 and PHB-2). Paradoxically, in C. elegans prohibitin depletion shortens the lifespan of wild type animals while dramatically extending that of metabolically compromised animals, such as daf-2-insulin-receptor mutants. Here we show that amongst the three kinases known to act do ...
Title of dissertation: THE INFLUENCE OF INSULIN-LIKE GROWTH FACTOR PATHWAY GENE POLYMORPHISMS ON THE STRENGTH TRAINING RESPONSE OF MUSCLE PHENOTYPES IN OLDER ADULTS Brian Dudley Hand, Doctor of Philosophy, 2006 Dissertation directed by: Professor Ben F. Hurley Department of Kinesiology Strength training (ST) is considered an intervention of choice for the prevention and treatment of the adverse consequences of sarcopenia. Our group previously reported that the CA dinucleotide repeat polymorphism ...
GH secretion was evaluated in 214 children and adolescents (age, 5-16 yr; 160 males and 54 females) with short stature (height, < or = 5th percentile) by assessing mean spontaneous overnight GH concentration (normal values, > or = 3 and 3.9 micrograms/L for prepubertal and pubertal subjects, respectively) and responsiveness to stimulation with GH-releasing hormone combined with pyridostigmine (normal peak values, > or = 20 micrograms/L). Plasma insulin-like growth factor-I (IGF-I) was a ...
Insulin receptor substrates (IRS) are phosphorylated by activated insulin/insulin-like growth factor I receptor tyrosine kinases, with this comprising an initial key event for downstream signaling and bioactivities. Despite the structural similarities, increasing evidence shows that IRS family proteins have nonredundant functions. Although the specificity of insulin/insulin-like growth factor signaling and biological responses partly reflects which IRS proteins are dominantly phosphorylated by t ...
The production of Long-R -IGF-1 (an IGF-1 fusion analog) by constant-rate, fed-batch fermentation of Escherichia coli yielded 2.6 g fusion protein/L, corresponding to an actual IGF-1 concentration of 2.2 g/L. A novel strategy employing three distinct feeding stages was developed which raised product concentration to 4.3 g/L (3.6 g/L of IGF-1) while minimising glucose and acetate accumulation. This improved productivity was not accompanied by an increase in inclusion body size. ...
Increased expression of insulin-like growth factor-I (IGF-I) in embryonic neural progenitors in vivo has been shown to accelerate neuron proliferation in the neocortex. In the present study, the in vivo actions of (IGF-I) on naturally occurring neuron death in the cerebral cortex were investigated during embryonic and early postnatal development in a line of transgenic (Tg) mice that overexpress IGF-I in the brain, directed by nestin genomic regulatory elements, beginning at least as early as em ...
Eight growth-hormone-deficient children were treated with recombinant human GH (rhGH). Results of the short-term metabolic response to rhGH performed at the start of therapy during a 5-day introduction period and long-term results on growth were analyzed. We could not find any correlation between the effects on the short-term metabolic test and the growth response during long-term therapy, namely between the urea and insulin-like growth factor-I response during the short test and the increase in ...
Life-span extension in laboratory rodents induced by long-term caloric restriction correlates with decreased serum insulin-like growth factor-I (IGF-I) levels. Reduced activity of the growth hormone/IGF-I signaling system slows aging and increases longevity in mutant mouse models. In the present study, we show that long-term caloric restriction achieved by two different interventions for 4 years, either laparoscopic-adjustable gastric banding or reducing diet, leads to reduced IGF-I serum levels ...
BACKGROUND Polysaccharide isolated from Bletilla striata, a well-known traditional Chinese medicine (Bletilla striata polysaccharide [BSP]) has been found to play important roles in endothelial cells proliferation, inducible nitric oxide stimulation, wound healing acceleration and other processes. Recent studies found that B. striata has anti-oxidative properties, however, potential anti-aging effects of BSP in whole organisms has not been characterized. OBJECTIVE To investigate whether BSP ha ...
The avian embryo has been a useful model system for studies on the role of insulin and its close relative insulin-like growth factor-I (IGF-I) in development. The unfertilized chicken egg contains both peptides from maternal origin, and the embryo expresses insulin and IGF-I before the major organs are formed. Insulin receptors and IGF-I receptors are found in the blastoderm and in all tissues examined during organogenesis. When exogenous insulin or IGF-I are added to the embryo, growth and diff ...
Although abundant mRNA for IGF-II has been detected in the human ovary, a role for IGF-II in steroidogenesis has not yet been established. In rat adipocytes, incubation with insulin greatly increases cell-surface IGF-II receptor (5-fold) and the receptor is rapidly internalised in the absence of insulin. We have therefore investigated the effects of insulin preincubation on the response of granulosa cells from unstimulated ovaries to a range of doses of IGF-II. In the absence of insulin, IGF-II ...
A growing body of evidence has been accumulated recently suggesting that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) affect cardiac function, but their mechanism(s) of action is unclear. In the present study, GH and IGF-1 were administered to isolated isovolumic aequorin-loaded rat whole hearts and ferret papillary muscles. Although GH had no effect on the indices of cardiac function, IGF-1 increased isovolumic developed pressure by 24% above baseline. The aequorin transients we ...
We have previously demonstrated that IGF-binding protein-1 (IGFBP-1) levels rise steadily during fasting, following an inverse relationship with insulin. The function of the IGFBP-1 rise is unknown, but it has been hypothesized that IGFBP-1 serves as a glucose counterregulatory hormone during fasting and hypoglycemia by binding free IGFs, thus inhibiting IGF interactions with IGF receptors. Our objective in this study was to determine levels of free and total IGFs during fasting together with th ...
Increasing evidence suggests that insulin-like growth factors I and II (IGF-I, IGF-II) have a regulatory role in animal granulosa cells. This study was undertaken to investigate the presence of IGF-I and IGF-II, as well as that of their binding proteins (BP), IGFBP-1 and IGFBP-3 in human serum and follicular fluid (FF). Preovulatory FF was obtained from 51 patients undergoing in-vitro fertilization. The IGFBP-1 level was found to be significantly higher (P less than 0.01) in FF than in serum, wh ...
Semantic Scholar extracted view of "Reply to Comment on: Ong KK, Petry CJ, Emmett PM et al.; ALSPAC study team (2004) Insulin sensitivity and secretion in normal children related to size at birth, postnatal growth, and plasma insulin-like growth factor-I levels. Diabetologia 47:1064–1070" by K. K. Ong et al. ...
INTRODUCTION Bone repair frequently requires time-consuming implant construction, particularly when using un-formed implants with poor handling properties. We therefore developed osteoinductive, micro-fibrous surface patterned demineralized bone matrix (DBM) fibers for engineering both defect-matched and general three-dimensional implants. METHODS AND RESULTS Implant molds were filled with demineralized human cortical bone fibers there were compressed and lyophilized, forming mechanically stro ...
BACKGROUND In trauma patients a specific pattern of the hormone endocrine response to injury has been described. Conflicting data exist regarding the hormonal changes during sepsis. We studied the time course and variability of the hormonal and metabolic responses to severe sepsis in twelve medical patients. METHODS Hormone levels were measured every 6 hours. Urinary nitrogen and 3-methylhistidine excretion were measured daily. Indirect calorimetry was used to calculate energy production rate ...
The cellular microenvironment impacts how signals are transduced by cells and plays a key role in tissue homeostasis. Although pH is generally well regulated, there are a number of situations where acidosis occurs and our work addresses how low pH impacts cell association of insulin-like growth factor-I (IGF-I) in the presence of IGF binding protein-3 (IGFBP-3). We have previously shown that IGF-I cell binding was enhanced in the presence of IGFBP-3 at low pH and now show that this binding is IG ...
Hypoglycemia is reported to be one of the manifestations of a patient with hypothalamic sarcoid infiltrates due to impaired counter-regulation of glucose. But, without hypothalamic lesion, patients with sarcoidosis would not be expected to have hypoglycemia. We recently identified a patient with an isolated sarcoidosis of the spleen who had experienced frequent fasting hypoglycemia which completely disappeared after splenectomy. During hypoglycemia, serum insulin was undetectable. Endocrinologic ...
Linear growth retardation is common in uncontrolled insulin-deficient diabetes, but individual organs such as kidney may hypertrophy. To explore whether this heterogeneity of response might be mediated by differential local insulin-like growth factor-I (IGF-I) gene regulation, we injected rats with ip saline, 65, 120, or 175 mg/kg streptozotocin (STZ). Diabetics were untreated or received daily insulin. Animals were killed 24, 48, or 72 h after documentation of diabetes, and liver, kidney, and l ...
OBJECTIVE Modest elevations in circulating IGF-I levels have been suggested to protect against the development of glucose intolerance in insulin-resistant subjects. To further understand the interactions of GH and IGF-I on beta-cell function and post-load glucose tolerance in glucose-intolerant subjects predisposed to diabetes, we performed a pilot study in 12 subjects with impaired glucose tolerance and the metabolic syndrome using a low GH dose (1.7 microg/kg per day) known to increase endogen ...
Aging is associated with low-grade neuroinflammation including primed microglia that may contribute to deficits in neural plasticity and cognitive function. The current study evaluated whether exercise modulates division and/or activation state of microglia in the dentate gyrus of the hippocampus, as activated microglia can express a classic inflammatory or an alternative neuroprotective phenotype. We also assessed hippocampal neurogenesis to determine whether changes in microglia were associate ...
CONTEXT The somatomedin/IGF hypothesis was based on the observation that GH was inactive when added to an in vitro incubation system but required a GH-dependent substance in the circulation to mediate its activity. Newer experimental evidence has led to several modifications of the hypothesis, but none of the proposed modifications accounts for all of the integrated actions of GH and IGF-I. In this paper, we propose an augmentative/counteractive modification of the existing hypothesis that takes ...
Bone loss with aging may at least in part be due to inadequate bone formation. In this study, we examined whether the proliferation of osteoblast-like cells in vitro in response to local and systemic factors might be attenuated with age. A total of 36 cultures of osteoblast-like cells were obtained from outgrowths of human trabecular bone. Parathyroid hormone, growth hormone, calcitonin, transforming growth factor beta, insulin-like growth factor I, and platelet-derived growth factor BB dose dep ...
Growth hormone plays a central role in the change in nutrient metabolism that occurs during the initiation of lactation. The actions of growth hormone are mediated by the growth hormone receptor (GHR) whose mRNA is present in three alternatively spliced forms (GHR 1A, 1B, and 1C). Liver-specific GHR 1A mRNA is transiently decreased around parturition, but the exact timing of the decline is not known. Our objective was to generate a daily profile for total GHR (GHRtot; all GHR transcripts), GHR 1 ...
The insulin-like growth factor system, which includes insulin-like growth factors (IGF-I and IGF-II), IGF receptors (IGF-IR and IGF-IIR) and IGF binding proteins (IGFBPs), plays an important role in epithelial growth, anti-apoptosis and mitogenesis. There is a growing body of evidence showing that IGFs control growth and proliferation of several types of cancer. This review introduces the latest information on the biology of the IGF system and its pathophysiological role in the development of co ...
Apolipoprotein M (apoM) is a novel apolipoprotein present mostly in high-density lipoprotein (HDL) in human plasma. In the present study, we demonstrate that insulin, insulin-like growth factor I (IGF-I), and IGF-I potential peptide (IGF-IPP) significantly inhibits apoM expression, in a dose- and a time-dependent manner, in the human hepatoma cell line, HepG2 cells. Insulin-induced down-regulation of apoM was blocked by AG1024 (a specific insulin receptor inhibitor) and LY294002 (a phosphatidyli ...
Insulin/insulin-like growth factor-I (IGF-I) hybrid receptors are composed of an alpha beta-heterodimer from an insulin receptor and an alpha beta-heterodimer from an IGF-I receptor. In this study, we evaluate the effect of insulin receptor overexpression on hybrid formation. The more human insulin receptors expressed in rodent fibroblasts, the greater the percentage of endogenous rat IGF-I receptors that form hybrid receptors. The IGF-I receptor in rodent fibroblasts has two receptor isoforms, ...
A minority of meningiomas are difficult to treat with surgery or radiotherapy, and chemotherapeutic alternatives are limited. This study aims to better understand pathways that are active in meningiomas, in order to direct future treatment strategies. We investigated the expression and activation of multiple growth factor receptors, their ligands and downstream signalling pathways in 30 meningiomas using immunohistochemistry. Expression was correlated with chromosome 22q loss. Membrane expressio ...
Hepatocellular carcinoma is mainly associated with viral hepatitis B and C. Activation of cell growth stimulator IGF-II gene is observed in tumor formation especially in viral associated hepatocellular carcinoma. Elevated IGF-II levels are indicator of increased risk for cholangiocellular and hepatocellular carcinomas through over saturation of IGF-II binding capacities with IGF receptors leading to cellular dedifferentiation. In HCV, core protein is believed to trans-activate host IGF-II recept ...
The present study was conducted to examine the relationship between plasma concentrations of testosterone, insulin-like growth factor I (IGF-I) and IGF-binding proteins (IGFBPs) during puberty, in male calves treated with GnRH or testosterone propionate. Twelve male Holstein calves (10 weeks old) were assigned to the control group (n = 6), the GnRH-treated group (n = 3) or the testosterone-treated group (n = 3). For 8 weeks, the GnRH-treated group received a single i.v. injection of GnRH (0.5 mi ...
Development in vitro is influenced by embryo density, serum, somatic cell co-culture and the production of 'embryotrophic' paracrine and autocrine factors. Research in our laboratory has focussed principally on the insulin-like growth factor (IGF) family. We have demonstrated that pre-attachment bovine and ovine embryos express mRNAs encoding a number of growth factor ligand and receptor genes including all members of the IGF ligand and receptor family throughout this developmental interval. In ...
The immunocytochemical localization of insulin-like growth factor I (IGF-I) and platelet-derived growth factor A (PDGF-A) chain ligands, PDGF-chain receptors, and the intermediate filaments cytokeratin, desmin, and vimentin in the tissue reorganization and development during the establishment of the porcine epitheliochorial placenta was studied at light and electron microscopic levels in sections of endometrium and/or placenta of gilts during early pregnancy up to day 40 postmating. The endometr ...
The insulin/insulin growth factor (IGF) pathway is a critical mediator of longevity and aging. Efforts to extend longevity by altering the insulin/IGF pathway may have varying effects on other physiological processes. Reduced insulin/IGF levels may decrease the incidence of certain cancers as well as the risk of developing metastatic disease. However, it may also increase the risk of developing cardiovascular disease as well as cardiovascular related mortality. Pursuing the right insulin/IGF pat ...
While the GH receptor (GHR) plays a key role during adult life, its role during fetal development is not well understood. Recent data suggest that GHRs are present in ovine fetal hepatic tissue at mid-gestation. However, the levels of GHR expression are markedly lower in fetal hepatic tissue in comparison with postnatal values. The present study investigates whether the neonatal induction of the hepatic GHR and plasma levels of IGF-I follow a pattern of strictly age-related development or whethe ...
Fat mass (FM) in overweight/obese subjects has a primary role in determining low-grade chronic inflammation and, in turn, insulin resistance (IR) and ectopic lipid storage within the liver. Obesity, aging, and FM influence the growth hormone/insulin-like growth factor (IGF)-I axis, and chronic inflammation might reduce IGF-I signaling. Altered IGF-I axis is frequently observed in patients with Hepatic steatosis (HS). We tested the hypothesis that FM, or spleen volume and C-reactive protein (CRP) ...
Fetuses swallow large volumes of amniotic fluid. Absence of swallowing results in gastrointestinal tract (GIT) growth deficits. While it is not yet known to what extent the growth factors present in amniotic fluid are involved in GIT ontogeny, milk-derived growth factors are considered to be important for neonatal growth. Our experiment tested the hypothesis that a luminal growth factor (insulin-like growth factor-I, IGF-I) can sustain or promote GIT growth in utero in a model of gastrointestina ...