Acid-labile subunit levels and the association with response to growth hormone treatment in short children born small for gestational age

Catch-Up Growth as a Risk Factor for Rapid Weight Gain, Earlier Menarche and Earlier Pubertal Growth Spurt in Girls Born Small for Gestational Age (SGA)-A Longitudinal Study

Most children born small for gestational age (SGA) have rapid postnatal growth. Despite its positive aspects, catch-up growth may affect the level of adipose tissue in the pre-pubertal and pubertal periods and therefore affect the age of puberty. The aim of this study was to determine the associations between size at birth, catch-up growth in infancy, BMI in peripubertal period, age at menarche, and the parameters of adolescent growth spurt of body height in girls born SGA. For 297 girls (22.6% SGA; 77.4% appropriate for gestational age (AGA)) complete body weight and height measurements and age at menarche were obtained. Adolescent growth spurt parameters were estimated using the JPA2 model (AUXAL SSI 3.1). Calculations were made in the Statistica 13 program using the Kruskal-Wallis and Kaplan-Meier tests. Girls born SGA with catch-up had the highest BMIs at the age of 8 years (H = 94.22, p < 0.001) and at menarche (H = 58.21, p < 0.001), experienced menarche earliest (H = 21.77, p < 0.001), same as the onset (H = 6.54, p = 0.012) and peak height velocity (H = 11.71, p = 0.003) of their adolescent growth spurt compared to SGA girls without catch-up and AGA girls. In SGA girls, catch-up growth has far-reaching consequences such as increased risk of fat accumulation and a rapid transition to puberty.

Insulin-Like Peptide Receptor-Mediated Signaling Pathways Orchestrate Regulation of Growth in the Pacific Oyster (Crassostrea gigas), as Revealed by Gene Expression Profiles

The involvement of insulin/insulin-like growth factor signaling (IIS) pathways in the growth regulation of marine invertebrates remains largely unexplored. In this study, we used a fast-growing Pacific oyster (Crassostrea gigas) variety “Haida No.1” as the material with which to unravel the role of IIS systems in growth regulation in oysters. Systematic bioinformatics analyses allowed us to identify major components of the IIS signaling pathway and insulin-like peptide receptor (ILPR)-mediated signaling pathways, including PI3K-AKT, RAS-MAPK, and TOR, in C. gigas. The expression levels of the major genes in IIS and its downstream signaling pathways were significantly higher in “Haida No.1” than in wild oysters, suggesting their involvement in the growth regulation of C. gigas. The expression profiles of IIS and its downstream signaling pathway genes were significantly altered by nutrient abundance and culture temperature. These results suggest that the IIS signaling pathway coupled with the ILPR-mediated signaling pathways orchestrate the regulation of energy metabolism to control growth in Pacific oysters.

New Horizons in Short Children Born Small for Gestational Age

Children born small for gestational age (SGA) comprise a heterogeneous group due to the varied nature of the cause. Approximately 85-90% have catch-up growth within the first 4 postnatal years, while the remainder remain short. In later life, children born SGA have an increased risk to develop metabolic abnormalities, including visceral adiposity, insulin resistance, and cardiovascular problems, and may have impaired pubertal onset and growth. The third "360° European Meeting on Growth and Endocrine Disorders" in Rome, Italy, in February 2018, funded by Merck KGaA, Germany, included a session that examined aspects of short children born SGA, with three presentations followed by a discussion period, on which this report is based. Children born SGA who remain short are eligible for GH treatment, which is an approved indication. GH treatment increases linear growth and can also improve some metabolic abnormalities. After stopping GH at near-adult height, metabolic parameters normalize, but pharmacological effects on lean body mass and fat mass are lost; continued monitoring of body composition and metabolic changes may be necessary. Guidelines have been published on diagnosis and management of children with Silver-Russell syndrome, who comprise a specific group of those born SGA; these children rarely have catch-up growth and GH treatment initiation as early as possible is recommended. Early and moderate pubertal growth spurt can occur in children born SGA, including those with Silver-Russell syndrome, and reduce adult height. Treatments that delay puberty, specifically metformin and gonadotropin releasing hormone analogs in combination with GH, have been proposed, but are used off-label, currently lack replication of data, and require further studies of efficacy and safety.

Current Insights into the Role of the Growth Hormone-Insulin-Like Growth Factor System in Short Children Born Small for Gestational Age

BACKGROUND

The reason for the insufficient catch-up growth seen in 10% of children born small for gestational age (SGA) is poorly understood. Disturbances in the growth hormone (GH) - insulin-like growth factor (IGF) axis might underlie this failure to show sufficient catch-up growth.

CONCLUSION

This review summarizes insights gained in the molecular and (epi) genetic mechanisms of the GH-IGF axis in short children born SGA. The most notable anomalies of the IGF system are the lowered IGF-I levels in both cord blood and the placenta, and the increased expression of IGF-binding proteins (IGFBP)-1 and IGFBP-2, which inhibit IGF-I, in the placenta of SGA neonates. These observations suggest a decreased bioactivity of IGF-I in utero. IGF-I levels remain reduced in SGA children with short stature, as well as IGFBP-3 and acid-labile subunit levels. Proteolysis of IGFBP-3 appears to be increased.

Children Born Small for Gestational Age: Differential Diagnosis, Molecular Genetic Evaluation, and Implications

Children born small for gestational age (SGA), defined as a birth weight and/or length below -2 SD score (SDS), comprise a heterogeneous group. The causes of SGA are multifactorial and include maternal lifestyle and obstetric factors, placental dysfunction, and numerous fetal (epi)genetic abnormalities. Short-term consequences of SGA include increased risks of hypothermia, polycythemia, and hypoglycemia. Although most SGA infants show catch-up growth by 2 years of age, ∼10% remain short. Short children born SGA are amenable to GH treatment, which increases their adult height by on average 1.25 SD. Add-on treatment with a gonadotropin-releasing hormone agonist may be considered in early pubertal children with an expected adult height below -2.5 SDS. A small birth size increases the risk of later neurodevelopmental problems and cardiometabolic diseases. GH treatment does not pose an additional risk.

Quantitative analysis of the concentrations of IGFs and several IGF-binding proteins in a large fibrous abdominal tumor and the circulation of a patient with hypoglycemia

The syndrome of nonislet cell tumor induced hypoglycemia (NICTH) represent extreme cases of excessive expression and production of incompletely processed high-molecular-mass pro-IGF-II forms (big IGF-II) by an often large tumor. Tumor-derived big IGF-II is responsible for enhanced insulin-like effects in the body through complicated mechanisms, leading to hypoglycemia. Case studies on NICTH usually focus on measurements of diagnostic parameters in the circulation of patients. Some studies have also reported on qualitative immunohistochemical analysis of tumor tissue, in particular with respect to the expression of IGF-II at the mRNA or protein level. However, quantitative data on the concentrations of IGFs and IGFBPs in tumor specimen causing NICTH, in relation to their corresponding plasma levels are lacking. Such an analysis would provide an estimate of the total potential of (big) IGF-II retained by the tumor and more insight in the relative levels of different IGFBPs and their origin in the circulation, that is, systemically induced by tumor related factors or directly tumor-derived. Here we investigated quantitatively the levels of IGFs and IGFBPs in a large, 1.76 kg weighing, solitary fibrous tumor from a typical case of NICTH using highly specific immunometric assays. Besides a high level of big IGF-II, patient's plasma also contained increased levels of both IGFBP-2 and -6 which declined after removal of the tumor. These IGFBPs have a higher affinity for (pro-) IGF-II than IGF-I and exhibit intrinsic IGF-independent bioactivities. Tumor tissue contained high amounts of big IGF-II and IGFBP-6, exceeding that in patient's circulation many-fold. A relatively low tumor content of IGFBP-2 was found suggesting that the preoperative high levels in plasma were attributable to systemic mechanisms. The background literature and possible implications of these findings are briefly discussed. Based on the present results we postulate that tumor tissue is not the source of the elevated levels of IGFBP-2 often seen in NICTH patients. Large tumors that cause NICTH can produce IGFBP-6 leading to enhanced levels of this IGFBP in the circulation. Hence, the measurement of IGFBP-6 in plasma may serve as an additional marker of this disease pattern.