Antepartal insulin-like growth factor concentrations indicating differences in the metabolic adaptive capacity of dairy cows

Cows with different Insulin-like Growth Factor-I (IGF-I) concentrations showed comparable expression levels of hepatic growth hormone receptor (GHR). Suppressor of cytokine signaling 2 (SOCS2), could be responsible for additional inhibition of the GHR signal cascade. The aims were to monitor cows with high or low antepartal IGF-I concentrations (IGF-I(high) or IGF-I(low)), evaluate the interrelationships of endocrine endpoints, and measure hepatic SOCS2 expression. Dairy cows (n = 20) were selected (240 to 254 days after artificial insemination (AI)). Blood samples were drawn daily (day -17 until calving) and IGF-I, GH, insulin, thyroid hormones, estradiol, and progesterone concentrations were measured. Liver biopsies were taken (day 264 +/- 1 after AI and postpartum) to measure mRNA expression (IGF-I, IGFBP-2, IGFBP-3, IGFBP-4, acid labile subunit (ALS), SOCS2, deiodinase1, GHR1A). IGF-I concentrations in the two groups were different (p 0.05). Thyroxine levels and ALS expression were higher in the IGF-I(high) cows compared to IGF-I(low) cows. Estradiol concentration tended to be greater in the IGF-I(low) group (p = 0.06). It was hypothesized that low IGF-I levels are associated with enhanced SOCS2 expression although this could not be decisively confirmed by the present study.

Insulin-like growth factor binding protein-3 in preterm infants with retinopathy of prematurity.

Background: Retinopathy of prematurity (ROP) is the main cause of visual impairment in preterm newborn infants. Objective: This study was conducted to determine whether insulin-like growth factor binding protein -3 (IGFBP-3) is associated with proliferative ROP and has a role in pathogenesis of the disease in premature infants. Materials and Methods: A total of 71 preterm infants born at or before 32 weeks of gestation participated in this study. Studied patients consisted of 41 neonates without vaso-proliferative findings of ROP as the control group and 30 preterm infants with evidence of severe ROP in follow up eye examination as the case group. Blood samples obtained from these infants 6-8 weeks after birth and blood levels of IGFBP-3 were measured using enzyme-linked immunosorbent assay (ELISA). Results: The mean gestation age and birth weight of the studied patients were 28.2±1.6 weeks and 1120.7±197 gram in the case group and 28.4±1.6 weeks and 1189.4±454 gram in the control group (P=0.25 and P=0.44 respectively). The infants in the case group had significantly lower Apgar score at first and 5 min after birth. Insulin-like growth factor binding protein -3 (IGFBP-3) was significantly lower in the patients with proliferative ROP than the patients without ROP [592.5±472.9 vs. 995.5±422.2 ng/ml (P=0.009)]. Using a cut-off point 770.45 ng/ml for the plasma IGFBP-3, we obtained a sensitivity of 65.9% and a specificity of 66.7% in the preterm infants with vasoproliferative ROP. Conclusion: Our data demonstrated that the blood levels IGFBP-3 was significantly lower in the patients with ROP and it is suspected that IGFBP-3 deficiency in the premature infants may have a pathogenetic role in proliferative ROP.

Insulin-like growth factors and their binding proteins in children with IDDM.

The structure of insulin-like growth factor (IGF), especially IGF-I, and its receptor is similar to that of insulin. Therefore, the changes of IGFs and IGF-binding proteins may be related to glucose homeostasis in children with insulin dependent diabetes mellitus (IDDM). Sixty-three fasting blood samples of 21 children with IDDM attending 3 consecutive diabetic clinics were studied. The HbA1c progressively decreased from the 1st to the 3rd visit. IGF-I levels, both total and free forms, were not significantly different from that of control. IGFBP-3 levels in 3 visits (3406+/-305, 3376+/-252, and 2406+/-247 ng/mL) were significantly lower than that of control (5020+/-415 ng/mL) with the p value of 0.007, 0.002, and < 0.001 respectively. IGFBP-1 levels in the 1st and 2nd visits (102.1+/-12.9 and 114.1+/-14.5 ng/mL) were significantly higher than that of control (60.1+/-15.2 ng/mL) with the p value of 0.03 and 0.01 respectively, but not in the 3rd visit. IGF-I level had a positive correlation with IGFBP-3 (R=0.56, p=0.01) and free IGF-I (R=0.53, p=0.01). Free IGF-I had a negative correlation with IGFBP-1 (R=-0.64, p=0.01). IGF-II at the 15 visit had a negative correlation with HbA1c (R=-0.49, p=0.047). The authors found no correlations between IGF-I, IGFBP-3, free IGF-I, IGFBP-1 and HbA1c in the study. The patients' height SDS followed the genetic height potential. It was, therefore, postulated that a near normal free IGF-I level in diabetic children resulted from a balance of interaction between IGFBP-1 and IGFBP-3 to total IGF-I in order to keep the normal metabolic status as much as possible.

The usefulness of serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) for evaluation of children with short stature.

The diagnostic value of serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) was studied in 24 growth hormone deficient (GHD) and 36 normal variant short stature (NVSS) children. The serum IGF-1 and IGFBP-3 concentrations were markedly below the 5th centile for chronological age in all 24 GHD children, but were in the low normal range for age in most of the NVSS children. The concentrations of IGF-1 and IGFBP-3 significantly correlated with peak GH concentration, height age, and bone age. To account for the age- and sex-dependency, IGF-1 and IGFBP-3 levels were transformed to standard deviation score (SDS). Using the -2 SDS as a cut-off level to differentiate between GHD and NVSS, the diagnostic value of IGF, as well as IGFBP-3, showed sensitivity 100 per cent, specificity 66.7 per cent, and accuracy 80 per cent. The combined use of IGF-1 and IGFBP-3 < -2 SDS improved the diagnostic value with sensitivity 100 per cent, specificity 77.8 per cent, and accuracy 86.7 per cent. We concluded that the serum concentrations of IGF-1 and IGFBP-3 could reflect endogenous GH secretion and could be used as a screening evaluation of GH status in short children.