Analysis of the IGF-system in milk from farm animals - Occurrence, regulation, and biomarker potential

IGFs and IGF-binding proteins (IGFBPs) are abundantly present in milk and in dairy products. Compared to the IGFs, the IGFBP have received less attention in milk, although truncated IGFBPs and IGFBP-glycosylation have been described in milk. Thereby, complex control of local IGF-effects can be assumed on the levels of IGFBPs, proteases, and protease inhibitors. The present review collects the current knowledge both on presence and regulation of IGFs and IGFBPs in milk particularly from dairy animal species. As a rule higher levels of IGF-I, IGF-II, and IGFBPs are measured around parturition if compared to later time-points of lactation. In all farm animal species included in this review, it is found that the relative abundancies of IGFBPs in milk and serum are similar, with IGFBP-3 and -2 characterized by higher concentrations if compared to IGFBP-4 or -5. The concentrations of IGFs and IGFBPs in milk or dairy products can be altered by hormones, dairy processing, or fermentation. Because milk can be used for non-invasive biomarker research, quality management, and health monitoring, we discuss novel directions of IGF-analysis and potential on-site biomarker research in milk.

Functional analysis of the IGF-system in milk

The development of milk during evolution is considered a more recent step to provide the neonate with adequate amounts of energy, nutrients, and specific hormonal signals thereby, granting a fast and efficient rate of postnatal growth and development. Since the insulin- or the insulin-like growth factor (IGF) systems were evolved much earlier, it can be assumed that the functionality of the IGF-system has been integrated into the novel matrix milk containing casein and whey proteins from the beginnings. In fact, IGFs and IGF-binding proteins (IGFBPs) are abundantly present in milk, which is particularly true for fore-milk or colostrum and the potential effects of milk-borne IGF-compounds on the consuming organisms have in fact been addressed by several studies. Those studies examined, if orally administered IGFs can be absorbed by the consumer's gastro-intestinal tract and thus contribute e.g. to the somatic growth of infants. A second line of studies assessed local effects of milk-borne IGFs on growth and development of the gastro-intestinal tract itself. Finally, distinct functions of isolated IGF-compounds for growth and involution of the mammary gland have also been provided in the past. While the consumption of milk seems not to represent a major source of endogenous IGFs, accumulating evidence indicates secondary effects of milk on the endogenous IGF-system, which may be mediated by micronutrients such as branched amino acids and metabolic programming. By contrast, direct effects on growth and development of oesophageal and intestinal cells have been observed if IGFs were administered orally.

The influence of nutrition on the insulin-like growth factor system and the concentrations of growth hormone, glucose, insulin, gonadotropins and progesterone in ovarian follicular fluid and plasma from adult female horses (Equus caballus)

BACKGROUND

Feed intake affects the GH-IGF system and may be a key factor in determining the ovarian follicular growth rate. In fat mares, the plasma IGF-1 concentration is high with low GH and a quick follicular growth rate, in contrast to values observed in thin mares. Nothing is known regarding the long-term effects of differential feed intake on the IGF system. The objective of this experiment was to quantify IGFs, IGFBPs, GH, glucose, insulin, gonadotropin and progesterone (P4) in blood and in preovulatory follicular fluid (FF) in relation to feeding levels in mares.

METHODS

Three years prior to the experiment, Welsh Pony mares were assigned to a restricted diet group (R, n = 10) or a well-fed group (WF, n = 9). All mares were in good health and exhibited differences in body weight and subcutaneous fat thickness. Follicular development was scanned daily and plasma was also collected daily. Preovulatory FF was collected by ultrasound-guided follicular aspiration. Hormone levels were assayed in FF and plasma with a validated RIA.

RESULTS

According to scans, the total number of follicles in group R was 53% lower than group WF. Insulin and IGF-1 concentrations were higher in WF than in R mares. GH and IGF-2 concentrations were lower in plasma from WF mares than from R mares, but the difference was not significant in FF. The IGFBP-2/IGFBP-3 ratio in FF was not affected by feeding but was dramatically increased in R mare plasma. No difference in gonadotropin concentration was found with the exception of FSH, which was higher in the plasma of R mares. On the day of puncture, P4 concentrations were not affected by feeding but were higher in preovulatory FF than in plasma.

CONCLUSIONS

The bioavailability of IGF-1 or IGF-2, represented by the IGFBP2/IGFBP3 ratio, is modified by feed intake in plasma but not in FF. These differences partially explain the variability in follicular growth observed between well-fed mares and mares on restricted diets.

Determination of IGFs and their binding proteins

The worldwide clinical and scientific interest in peptides belonging to the insulin-like growth factor (IGF) system has brought along a call for standardization of assays used to quantify the different IGF related proteins. This relates in particular to the measurement of IGF-I, which has stood the test of time as an important biochemical tool in the diagnosis and treatment of growth hormone (GH) related disorders. The first international consensus statement on the measurement of IGF-I in 2011 represents an important milestone and will undoubtedly improve commutability of reference ranges for IGF-I and clinically applicable cut-off values. By contrast, there is no consensus addressing the measurements of the other IGF-related peptides. Nevertheless, measurement of these peptides may be of interest, either as additional tools in GH disorders or as prognostic biomarkers of various diseases. Therefore, standardization of assays for the other IGF-related peptides is highly relevant. This chapter discusses the recent consensus on IGF-I measurements and how this approach may be applied to measurement of the other IGF-related peptides. In addition, assay pitfalls, pre- and post-analytical challenges, alternative methods for IGF-I measurements and potential assays of tomorrow will be discussed.

Evaluation of protein expression pattern of stanniocalcin 2, insulin-like growth factor-binding protein 7, inhibin beta A and four and a half LIM domains 1 in esophageal squamous cell carcinoma

The pathogenesis of esophageal squamous cell carcinoma (ESCC) involves both genetic and environmental factors. Previously, we have carried out gene and protein expression profiling of ESCC using DNA microarrays and mass spectrometry-based quantitative proteomics, respectively. These studies resulted in identification of several potential biomarkers of ESCC, some with known reports of differential expression in the scientific literature and others that were novel observations from our studies. We report systematic validation of selected markers from our studies on a larger cohort of cancer tissue sections by immunohistochemical labeling of tissue microarrays. We have validated expression of insulin-like growth factor-binding protein 7 (IGFBP7), stanniocalcin 2 (STC2), inhibin beta A (INHBA) and four and a half LIM domains 1 (FHL1). Immunohistochemical labeling with anti-stanniocalcin 2 antibody demonstrated its overexpression in 132/140 (94%) cases, IGFBP7 showed overexpression in 127/140 (91%) cases and overexpression of INHBA was observed in 62/105 (59%) of ESCC cases. In contrast, FHL1 expression was observed only in 12/143 (8%) of ESCC cases suggesting its possible involvement in tumor suppression. These data suggest that IGFBP7, INHBA, STC2 and FHL1 might play an important role in ESCC tumorigenesis, which can be explored in future studies. Overall, our findings open up new avenues for development of novel therapeutics and/or diagnostic approaches in ESCC.

Development of IGF signaling antibody arrays for the identification of hepatocellular carcinoma biomarkers

Purpose

Our objective was to develop a system to simultaneously and quantitatively measure the expression levels of the insulin-like growth factor (IGF) family proteins in numerous samples and to apply this approach to profile the IGF family proteins levels in cancer and adjacent tissues from patients with hepatocellular carcinoma (HCC).

Experimental Design

Antibodies against ten IGF family proteins (IGF-1, IGF-1R, IGF-2, IGF-2R, IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6, and Insulin) were immobilized on the surface of a glass slide in an array format to create an IGF signaling antibody array. Tissue lysates prepared from patient's liver cancer tissues and adjacent tissues were then applied to the arrays. The proteins captured by antibodies on the arrays were then incubated with a cocktail of biotinylated detection antibodies and visualized with a fluorescence detection system. By comparison with standard protein amount, the exact protein concentrations in the samples can be determined. The expression levels of the ten IGF family proteins in 25 pairs of HCC and adjacent tissues were quantitatively measured using this novel antibody array technology. The differential expression levels between cancer tissues and adjacent tissues were statistically analyzed.

Results

A novel IGF signaling antibody array was developed which allows the researcher to simultaneously detect ten proteins involved in IGF signal pathway with high sensitivity and specificity. Using this approach, we found that the levels of IGF-2R and IGFBP-2 in HCC tissues were higher than those in adjacent tissues.

Conclusion

Our IGF signaling antibody array which can detect the expression of ten IGF family members with high sensitivity and specificity will undoubtedly prove a powerful tool for drug and biomarker discovery.

Quantification of the GH/IGF-axis components: lessons from human studies

Originally, the circulating bioactivity of IGF-I was estimated by bioassays measuring the ability of serum to stimulate uptake of labeled sulfate or thymidine in cultures of costal cartilage or by the ability of serum to stimulate the uptake of glucose in fat tissue cultures. However, because of their laborious and unspecific nature, the original bioassays were quickly abandoned with the development of the first RIA for IGF-I in 1977. Consequently, for the past three decades the endogenous IGF-I bioactivity has been almost exclusively estimated by the use of immunoassays. Beyond any doubt, the immunoassays have provided an extensive insight into IGF-I physiology and pathophysiology. However, immunoassays ignore the presence of the IGFBPs, which are important regulators of IGF-I action in vivo. In addition, immunoassays do not consider the presence of IGF-II, which also interacts with the IGF-I receptor (IGF-IR). This aroused our interest to reintroduce the bioassay; therefore, we established a cell-based kinase receptor activation (KIRA) assay based on cells transfected with the human IGF-IR. The output signal of the KIRA assay is IGF-IR phosphorylation, and, as such, it is highly specific. Further, because detection of phosphorylated IGF-IRs is based on modern immunoassay techniques, the overall performance of the assay is close to that of a traditional IGF-I immunoassay. The first part of this review comprises a short description of the bioassay, and a more in-depth presentation of the data that have been obtained so far. It will be demonstrated that the bioassay is indeed able to yield novel information on the IGF system, most likely because it is able to integrate the different components of the IGF system into one signal: IGF-IR activation. As IGF-I, circulating GH is bound to larger proteins, the far most important GH-binding protein (GHBP) is identical to the extracellular domain of the GH receptor (GHR). Because of its origin, GHBP binds GH with the same affinity as GHR and, consequently, GHBP may affect GH bioactivity as well as pharmacokinetics. To improve our knowledge on the complex interaction between GH and GHBP in vivo, we found it of interest to develop a method for determination of free GH. To this end, we developed an ultrafiltration assay that enabled isolation of free GH in undiluted serum during approached in vivo-like conditions. The last part of this review presents our current data on free GH and its interaction with GHBP.

Diurnal secretion profiles of growth hormone, thyrotrophin and prolactin in Parkinson's disease

Recently, a massive loss of both hypocretin and melanin-concentrating hormone (MCH) neurones was found in the hypothalamus of Parkinson's disease (PD) patients. Because both hypocretin and MCH play a key role in the regulation of sleep, energy homeostasis and autonomic function, partly by modulation of the somatotrophic, thyrotrophic and lactotrophic axes, neuroendocrine dysregulation may contribute to some of the non-motor features of PD. In eight de novo, medication-free PD patients and eight age-, sex- and body mass index-matched controls, we measured serum levels of growth hormone (GH), thyroid-stimulating hormone (TSH) and prolactin every 10 min for 24 h. Auto-deconvolution, cosinor and approximate entropy analysis were applied to quantify GH, TSH and prolactin secretion rates, diurnal rhythmicity, as well as regularity of hormone release. Sleep was polygraphically-recorded throughout the night. Total 24-h secretion of GH (191 ± 31 versus 130 ± 39 mU/l/24 h), TSH (38 ± 9 versus 36 ± 2 mU/l/24 h) and prolactin (102 ± 14 versus 116 ± 17 μg/l/24 h), as well as their diurnal rhythmicity and regularity of release, were not significantly different between PD patients and controls (all P ≥ 0.12). Fasting levels of insulin-like growth factor-1 were also unaltered in PD patients. However, free thyroxine (T(4) ) levels were significantly higher in PD patients compared to controls (16.19 ± 0.80 versus 13.88 ± 0.40 pmol/l; P = 0.031). In PD patients, prolactin levels were related to disease duration (r = 0.76, P = 0.028), whereas both GH (r = -0.91, P = 0.002) and free T(4) (r = -0.71, P = 0.050) levels correlated inversely with body fat content. Apart from a mild increase in free T(4) levels, we found no indications for altered somatotrophic, thyrotrophic and lactotrophic axes activity in early-stage PD patients.

Components of the porcine anterior pituitary insulin-like growth factor system throughout the estrous cycle

Components of the circulating and anterior pituitary insulin-like growth factor (IGF) system vary in response to steroids in pigs. However, whether serum and anterior pituitary concentrations of the IGF system vary throughout the estrous cycle has not been determined. To further examine this relationship, estrus was synchronized in 40 gilts of similar age and weight (180 d; 120 kg) by feeding 15 mg altrenogest for 15 d to synchronize estrus. Gilts were checked twice daily for expression of estrus beginning 3 d after the end of altrenogest treatment and continuing for 7 d. The first day each gilt exhibited estrus was designated as day 1 of the estrous cycle. Blood samples were obtained by jugular venipuncture on days 1, 4, 7, 10, 13, 16, 19, and 22 of the estrous cycle. On days 7, 13, 19, and 22 of the estrous cycle 10 pigs were killed and anterior pituitary glands (AP) were collected. Serum concentrations of IGF-I and AP concentrations of IGF-I were determined by radioimmunoassay. Relative amounts of AP IGF binding protein (IGFBP) were determined by western ligand blot analysis. Relative expression of AP IGF-I, IGF-I receptor (IGF-I-R), gonadotropin-releasing hormone receptor (GnRHR), and luteinizing hormone (LH)-β subunit were determined by real-time reverse transcription polymerase chain reaction. Serum concentrations of IGF-I fluctuated throughout the estrous cycle. Mean serum concentrations of IGF-I decreased (P < 0.02) from day 1 through day 10, increased (P < 0.02) on days 13 through 16, and then decreased (P < 0.02) from days 19 through 22. Mean AP concentrations of IGF-I were greater (P < 0.03) on day 19 than on all other days, whereas no difference was detected (P > 0.05) in mean AP concentrations of IGF-I on days 7, 13, and 22. Mean relative amounts of AP IGFBP-2 and -5 were each greater (P < 0.02) in gilts on day 19 than on all other days, whereas no difference was detected (P > 0.05) in mean relative amounts of AP IGFBP-2 and -5 among pigs on days 7, 13, and 22 of the estrous cycle. Relative expression AP IGF-I was greater (P < 0.05) on days 13, 19, and 22 than on day 7 of the estrous cycle. Similarly, the relative expression of AP IGF-IR was increased (P < 0.05) in gilts on days 13, 19, and 22 compared with day 7. The relative expression of GnRHR was greater (P < 0.05) on days 13 and 22 of the estrous cycle than on day 7. The relative expression of LHβ subunit was greater (P < 0.05) on day 19 of the estrous cycle than on days 7, 13, and 22. Anterior pituitary release of LH throughout the porcine estrous cycle may be modulated by changes in the intrapituitary IGF system.

Exercise training, physical fitness and the growth hormone-insulin-like growth factor-1 axis and cytokine balance

The effect of exercise training on anabolic hormones and inflammatory mediators is particularly important during childhood and puberty, since during this period there is a spontaneous increase in anabolic hormones that leads to the marked puberty-related growth spurt. Therefore, any training-associated hormonal and/or inflammatory effect during this critical period may have profound consequences on growth and development, especially if the effect is maintained for long periods. Several studies suggest the hypothesis that a sudden imposition of a training program which is associated with substantial increase in energy expenditure leads initially to an increase in pro-inflammatory cytokines, and as a consequence, to decreases in IGF-1 levels. Further, if the training adaptation is successful, the proinflammatory cytokines fall, and with that decrease, the suppression of IGF-1 diminishes, an anabolic 'rebound' in the GH-IGF-1 axis may ensue, and IGF-1 level exceed the pretraining level. Exactly how and when this switch takes place, and whether the initial catabolic-type stage is necessary for the ultimate anabolic adaptation remains unknown. Consistent with the two phases hypothesis, longer periods of training were indeed associated with stable or with increases in circulating GH and IGF-1 levels. Despite the early training-associated decrease in circulating IGF-1 levels, there is an increase in muscle mass and fitness may improve, suggesting that the local tissue effect of exercise on growth factors differ from systemic effects. Total caloric intake as well as macronutrient content, consumption and timing influence the anabolic and inflammatory response to training. Finally, changes in the balance of anabolic and catabolic hormones and inflammatory mediators during the training season may help elite athletes and their coaches in their training and preparation for competition.

Marked reductions in bioactive insulin-like growth factor I (IGF-I) during hemodialysis

OBJECTIVE

Hemodialysis (HD) patients lose lean body mass, even when they are adequately dialysed. One reason may be a decreased activity of the IGF-system. However, data on changes in bioactive IGF-I during HD are sparse.

DESIGN

Ten stable, non-diabetic HD patients were studied with 30 min intervals during a scheduled HD, with blood sampling before (-15 and 0 min), during (4 h) and after (1 h) the session. Patients were fasted for at least 6 h before and during the study. Arterial and venous blood was sampled for determination of IGF-I bioactivity, free and total IGF-I and IGF-II, IGF binding protein-1 (IGFBP-1), IGFBP-1 complexed IGF-I and IGFBP-2.

RESULTS

Total IGF-I and -II decreased marginally (<12%) at the very end of the study (P<0.05). By contrast, at 3 h free and bioactive IGF-I had declined by approximately 35% and 50%, respectively, and levels remained suppressed for the rest of the study (P<0.05). Concomitantly, IGFBP-1 and IGFBP-1:IGF-I complex formation increased 5.0-fold and 2.6-fold, respectively (P<0.05). By contrast, IGFBP-2 did not increase as a result of HD. No major differences between arterial and venous concentrations were observed.

CONCLUSION

Despite marginal reductions in total IGF-I and -II, bioactive and free IGF-I declined markedly during and after HD. This is likely a consequence of the increase in IGFBP-1, sequestering free IGF-I, and reducing bioactive IGF-I. Based on the present data we hypothesize that the catabolism induced by HD is in part related to the observed reductions in bioactive IGF-I.

Insulin-like growth factor binding protein: a possible marker for the metabolic syndrome?

Insulin-like growth factor (IGF) binding proteins (IGFBPs) moved on to contain both IGF high- and low-affinity binders, exerting mitogenic and metabolic actions through its complex interplay between IGF/insulin and its IGF/insulin-independent manner. Progress on the metabolic-related function of IGFBPs has been rapid in recent years. A wealth of studies in 3T3-L1 adipocytes and the transgenic mice models demonstrated that IGFBPs played important roles in the pathogenesis of obesity and insulin resistance. Studies conducted in humans demonstrated the close relation between IGFBPs and the components of the metabolic syndrome. Abnormal expression of IGFBP was detected in various states of the metabolic disorders, suggesting that it could be used as a convenient and sensitive marker of insulin resistance, identification of insulin-resistant individuals at high cardiovascular risk, and may be an earlier marker of the metabolic syndrome. These exciting findings bring us new insight into the elucidation of the metabolic syndrome, which may have important clinical implications.

Racial differences in the association between body mass index and serum IGF1, IGF2, and IGFBP3

African-American (AA) race/ethnicity, lower body mass index (BMI), and higher IGF1 levels are associated with premenopausal breast cancer risk. This cross-sectional analysis investigated whether BMI or BMI at age 21 years contributes to racial differences in IGF1, IGF2, IGF-binding protein 3 (IGFBP3), or free IGF1. Participants included 816 white and 821 AA women between ages 40 and 79 years across a wide BMI range (18.5-40 kg/m(2)). Compared with white women, AA women had higher mean IGF1 (146.3 vs 134.4 ng/ml) and free IGF1 (0.145 vs 0.127) levels, and lower IGF2 (1633.0 vs 1769.3 ng/ml) and IGFBP3 (3663.3 vs 3842.5 ng/ml) levels (all P<0.01; adjusted for age, height, BMI, BMI at age 21 years, and menopausal status). Regardless of race, IGF1 and free IGF1 levels rose sharply as BMI increased to 22-24 kg/m(2), and then declined thereafter, while IGF2 and IGFBP3 levels tended to rise with BMI. In contrast, BMI at age 21 years was inversely associated with all IGF levels, but only among white women (P-interaction=0.01). With the decline in IGF1 with BMI at age 21 years among whites, racial differences in IGF1 significantly increased among women who were obese in early adulthood. In summary, BMI was associated with IGF1 levels regardless of race/ethnicity, while obesity during childhood or young adulthood may have a greater impact on IGF1 levels among white women. The effects of obesity throughout life on the IGF axis and racial differences in breast cancer risk require study.

The current status of IGF-I assays--a 2009 update

For almost three decades, the measurement of circulating IGF-I has constituted a highly important biochemical tool in the management of GH disorders. In fact, in acromegaly the importance of circulating IGF-I has increased following the introduction of the GH receptor antagonist pegvisomant, as the use of this drug makes it impossible to use circulating GH as a monitor of disease activity. In addition, determination of circulating IGF-I constitutes a valuable scientific tool in various research areas, from epidemiological investigations through clinical trials and experimental studies. The multiple facets of IGF-I physiology and patho-physiology may explain why numerous endocrine laboratories have invested in IGF-I assays, by means of either in-house assays or commercial kits. However, despite its widespread use, the measurement of IGF-I is by no means trivial. On the contrary, the pronounced binding of IGF-I to the high-affinity IGF-binding proteins (IGFBPs) constitutes a notorious source of error, which has necessitated the development of methods that more or less successfully circumvent interference from the IGFBPs. Furthermore, there are some unsolved issues with the international standardization of the different IGF-I assays and there is no consensus regarding the procedures used when collecting and storing samples for measurement of circulating IGF-I. The aim of this review is to discuss the current state of the art of IGF-I immunoassays and to present the current analytical problems with IGF-I measurements. Finally, we would like to suggest an agenda that may be used when trying to produce internationally accepted uniform requirements for future IGF-I assays.

Ovarian cysts in high-yielding dairy cows

We examined the hormonal and morphologic changes associated with ovarian cyst formation in high-yielding dairy cows. Follicle fluid was aspirated from 90 cysts and 15 preovulatory and 18 subordinate follicles and used for hormonal determination. Pieces of cystic wall were subjected to morphologic and immunohistochemical evaluation. Cysts were characterized by low concentrations of insulin, insulin-like growth factor-I (IGF-I), and glucose and high activity of IGF binding proteins (IGFBPs). Insulin and IGF-I levels were (mean+/-SEM) 205+/-22 pg/mL and 146+/-42 ng/mL in preovulatory follicles and 3+/-1 pg/mL and 61+/-6 ng/mL in cysts, respectively (P<0.001). Insulin-like growth factor-binding proteins activity was about 10 times higher in cysts than in preovulatory follicles. Cysts were classified into three types according to their estradiol-to-progesterone (E/P) ratio. Type 1 cysts (n=23) exhibited the highest E/P ratio (10.8+/-2.3), partial loss of granulosa cells, and severe morphologic changes in the theca interna. Expression of P(450) side-chain cleavage and P(450) 17 alpha-hydroxylase was noted in theca cells and expression of inhibin-alpha in granulosa cells. Type 2 cysts (n=35) had a low E/P ratio (0.07+/-0.02), and patches of luteal-like tissue in the cystic wall. Type 3 cysts (n=32) had an E/P ratio of 0.91+/-0.17, and no recognizable granulosa or theca cells. In summary, intrafollicular steroid levels as expressed by E/P ratio, together with IGF-I and insulin levels and morphologic changes in the follicular wall, may serve as accurate cyst-classification parameters. Because IGF-I and/or insulin play an essential role in the final stage of follicle development, it can be speculated that abnormal levels of these metabolic hormones might lead to follicle dysfunction, resulting in follicular regression or cyst formation.

Fresh-frozen plasma as a source of exogenous insulin-like growth factor-I in the extremely preterm infant

CONTEXT

Preterm birth is followed by a decrease in circulatory levels of IGF-I and IGF binding protein (IGFBP)-3, proteins with important neurogenic and angiogenic properties.

OBJECTIVE

Our objective was to evaluate the effects of iv administration of fresh-frozen plasma (FFP) from adult donors on circulatory levels of IGF-I and IGFBP-3 in extremely preterm infants.

DESIGN, SETTING, AND PATIENTS

A prospective cohort study was performed in 20 extremely preterm infants [mean (SD) gestational age 25.3 (1.3) wk] with clinical requirement of FFP during the first postnatal week. Sampling was performed before initiation of transfusion, directly after, and at 6, 12, 24, and 48 h after completed FFP transfusion.

MAIN OUTCOME MEASURES

Concentrations of IGF-I and IGFBP-3 before and after transfusion of FFP were determined.

RESULTS

FFP with a mean (SD) volume of 11 ml/kg (3.1) was administered at a median postnatal age of 2 d (range 1-7). Mean (SD) IGF-I and IGFBP-3 concentrations in administered FFP were 130 (39) and 2840 microg/liter (615), respectively. Immediately after FFP transfusion, mean (SD) concentrations of IGF-I increased by 133% from 11 (6.4) to 25 microg/liter (9.3) (P < 0.001) and IGFBP-3 by 61% from 815 (451) to 1311 microg/liter (508) (P < 0.001). Concentrations of IGF-I and IGFBP-3 remained higher at 6 (P < 0.001, P = 0.009) and 12 h (P = 0.017, P = 0.018), respectively, as compared with concentrations before FFP transfusion. Typical half-life of administrated IGF-I was 3.4 h for a 1-kg infant.

CONCLUSION

Transfusion of FFP to extremely preterm infants during the first postnatal week elevates levels of IGF-I and IGFBP-3.

Cellular and molecular regulation of muscle growth and development in meat animals1,2

Although in vivo and in vitro studies have established that anabolic steroids, transforming growth factor-beta (TGF-beta), and myostatin affect muscle growth in meat-producing animals, their mechanisms of action are not completely understood. Anabolic steroids have been widely used as growth promoters in feedlot cattle for over 50 yr. A growing body of evidence suggests that increased muscle levels of IGF-I and increased muscle satellite cell numbers play a role in anabolic steroid enhanced muscle growth. In contrast to anabolic steroids, the members of the TGF-beta-myostatin family suppress muscle growth in vivo and suppress both proliferation and differentiation of cultured myogenic cells. Recent evidence suggests that IGFBP-3 and IGFBP-5 play a role in mediating the proliferation-suppressing actions of both TGF-beta and myostatin on cultured myogenic cells. Consequently, this review will focus on the roles of IGF-I and IGFBP in the cellular and molecular mechanisms of action of anabolic steroids and TGF-beta and myostatin, respectively.

Large variation in steroid concentrations and insulin-like growth factor binding proteins exists among individual small antral follicles collected from within cows at random stages of the estrous cycle

Variation in the biochemical status of individual small (< or = 5 mm diameter) antral follicles within the ovaries of a cow at any given time likely influences the capacity for undergoing recruitment, selection, and establishing dominance. The objectives of this study were to provide insight into the magnitude of variation in follicular fluid concentrations of steroids and activities of IGFBP that exists among individual small antral follicles within and between cows, and to determine the relationships between follicular fluid IGFBP and steroid concentrations in these follicles. A total of 108 small antral follicles were collected from 6 cows at random stages of the estrous cycle, with 10 to 26 follicles/cow. Concentrations of steroids (ng/mL of follicular fluid) in the overall population of follicles ranged from 0.1 (lowest detectable limit) to 51 for estradiol (E2), 4 to 1,149 for progesterone (P4), and 5 to 504 for androstenedione (A4). Concentrations of E2 and A4 were associated positively (r = 0.2; P < 0.02), but E2 (r = -0.4) and A4 (r = -0.4) were associated negatively, with P4. The proportion of variation in steroid concentrations accounted for by differences among animals (P < 0.05) was small for E2 (12%), moderate for P4 (43%), and greatest for A4 (74%). Least differences between minimum and maximum concentrations of steroids observed in follicles from within a cow were 21-, 5.5-, and 3.5-fold for E2, P4, and A4, respectively, whereas the greatest differences between minimum and maximum concentrations were 505-, 108-, and 26-fold for E2, P4, and A4, respectively. Ranges of IGFBP concentrations (arbitrary densitometer units) detected in fluid from a sub-sample of 43 follicles were 1.18 to 4.50 for IGFBP-3, 0.54 to 4.68 for IGFBP-2, 0.07 to 2.56 for IGFBP-4, and 0.01 to 6.71 for IGFBP-5. Concentrations of E2 were correlated negatively with each IGFBP (r = -0.4 to -0.8; P < 0.05) except IGFBP-3. In contrast, concentrations of A4 were correlated positively with IGFBP-3 (r = 0.4; P < 0.05) but were not correlated with other IGFBP. Concentrations of P4 were correlated positively (r > 0.4; P < 0.05) with IGFBP-4 and -5. The results indicate that steroid concentrations and IGFBP activities vary substantially among small antral follicles collected from within and among individual animals and that increasing production of E2, the hallmark of a developing follicle, was associated with reduced activity of all IGFBP except IGFBP-3, thereby implicating these IGFBP in the regulation of follicular recruitment.

Growth hormone therapy does not alter the insulin-like growth factor-I/insulin-like growth factor binding protein-3 molar ratio in growth hormone-deficient children

BACKGROUND

Recent studies have linked raised levels of IGF-I and/or reduced levels of its main binding protein, IGF binding protein (IGFBP)-3, with the risk of developing cancer. A GH dose-dependent increase in IGF-I/IGFBP-3 molar ratio has been reported in subjects treated with GH, raising concern about the long-term safety.

OBJECTIVE

The aim of this study was to evaluate changes in serum IGF-I, IGFBP-3, and IGF-I/IGFBP-3 molar ratio over the first 12 months of replacement GH therapy in GH deficient (GHD) children.

METHODS

The study included 20 GHD children who had not previously received GH treatment, and 40 untreated non-GHD short children closely matched for age, gender, pubertal stage, and body mass index (BMI), as controls. Serum IGF-I, IGFBP-3 levels were measured before and after 12 months of GH treatment. Based on the molecular weight of IGF-I (7500) and IGFBP- 3 (40,000, mean of glycosylated variants), we calculated the molar ratio of IGF-I/IGFBP-3.

RESULTS

IGF-I/IGFBP-3 molar ratio significantly increased during GH therapy (p=0.01). No significant difference in IGF-I/IGFBP-3 ratio was found between GHD children and controls at the different time points. In the multiple regression analysis, BMI (beta=0.33) and age (beta=0.33) proved to be the major predictors of the IGF-I/IGFBP-3 molar ratio (adjusted r2=0.53, p<0.0001).

CONCLUSIONS

Our results suggest that at a conventional replacement dose GH does not alter the IGF-I/IGFBP-3 molar ratio. Potential fears related to long-term cancer risk are likely to be greatest in patients exposed to high-dose GH therapy and with genetic predisposition to high IGF-I and/or low IGFBP-3 concentrations.

Differential influence of open surgery and sepsis on the circulating insulin-like growth factors and their binding proteins as representative metabolic markers

OBJECTIVES

In critical illnesses and stress conditions many endocrine systems are disturbed. In the current study we determined the influence of open surgery, post-operative sepsis and its early therapy on the components of the insulin-like growth factor (IGF) system in patients with malignant gastric or pancreatic tumors.

DESIGN AND METHODS

Twenty-one patients and eighty-one age- and sex-matched healthy subjects were included in this study. IGF-I, IGF-II, IGF binding proteins (IGFBPs), cortisol, insulin and protein concentrations (total, albumin and IgG) were determined pre-operatively, post-operatively, when sepsis was diagnosed and 48 h after initiating therapy.

RESULTS

The concentrations of circulating IGF-I, IGF-II and IGFBP-3 were significantly lower in pre-operative patients compared to healthy subjects. Sepsis caused a further decrease in IGF-I and IGFBP-3 but an increase in IGFBP-1, IGFBP-2 and IGFBP-4 resulting in a redistribution of IGF molecules from ternary to binary complexes.

CONCLUSIONS

The presence of malignant gastric or pancreatic tumors followed by post-operative sepsis caused a serious misbalance in components of the IGF system which failed to recover during the time of our longitudinal study.

Fetal programming of colon cancer in adult rats: correlations with altered neonatal growth trajectory, circulating IGF-I and IGF binding proteins, and testosterone

We examined effects of dietary soy protein isolate (SPI) or genistein (GEN; soy isoflavone) during pregnancy on development of colon cancer in male progeny Sprague-Dawley rats. Four groups of rats were used: a lifetime casein-fed group (CAS; control diet), a lifetime SPI-fed group (positive control for protective effect of diet on colon carcinogenesis), a group whose dams received SPI only during pregnancy and CAS thereafter (SPI/CAS), and a group whose dams received CAS+GEN only during pregnancy and CAS thereafter (GEN/CAS). At 47 and 55 days of age, male progeny were administered the intestinal carcinogen azoxymethane (AOM). Tumors, endocrine status, and colon gene expression were evaluated at 20 week post-AOM. The SPI group had 47% decreased colon tumor incidence compared with the CAS group (P<0.05), whereas SPI/CAS, GEN/CAS, and CAS groups did not differ in this regard. Maternal-only SPI increased the percentage of animals bearing multiple colon tumors (P<0.05), an effect not mimicked by GEN. Serum insulin and leptin concentrations were decreased by lifetime SPI (P<0.05), whereas serum IGF-I was elevated in the SPI/CAS group (P<0.05). The SPI/CAS group had reduced serum testosterone levels (P<0.05) and exhibited a tendency for increased mucosal expression of IGF-I receptor and glucose transporter-1 mRNAs. Results indicate an effect of dietary protein type during pregnancy on colon tumor multiplicity and colon tissue gene expression, and serum IGF-I and testosterone in progeny rats as later adults.

Indications, limitations and pitfalls in the determination of human growth hormone, IGF-I and their binding proteins

Deviations from normal growth are a major part of Pediatric Endocrinology. The principal post-natal growth promoting hormones are pituitary growth hormone (GH) and insulin-like growth factor-I (IGF-I). The GH-IGF-I axis has many links and portals, the secrets of which have been disclosed in recent years by scientific advances (genetic and biochemical technologies). In this article, we describe the players in the GH axis, the auxological indications for performing GH evaluation tests, enumerate the most frequently used tests and discuss the laboratory tests which help to define the pathological entities along the GH axis. Emphasis is put on the limitations of methods used, lack of standards, norms and the possible errors in diagnosis and treatment indications that may evolve. As both hGH and IGF-I immunoassay measurements represent cornerstones in the diagnosis and monitoring of the different etiological entities presenting with short stature, clinicians must have an insight into the variability and limitations of these analytical techniques. Interpretation of biochemical results without proper reference data and without knowledge of the assay-inherent characteristics inevitably leads to misdiagnosis, unnecessary further testing and treatment and imposes a burden on the child, family and the health care system.

Insulin-like growth factor binding proteins in follicular fluid from morphologically distinct healthy and atretic bovine antral follicles

In bovine follicles 2-5 mm in diameter, two morphologically distinct types of healthy follicles and two types of atretic follicles have been described recently. Healthy follicles either have columnar basal granulosa cells with follicular basal lamina composed of many layers or 'loops' or they have rounded basal cells with a conventional single-layered, aligned follicular basal lamina. In atretic follicles, cell death either commences at the basal layer and progresses to the antrum (basal atresia) with macrophage penetration of the membrana granulosa or death progresses from the antrum in a basal direction (antral atresia). Little is known about how these different phenotypes develop. To determine whether insulin-like growth factor binding protein (IGFBP) levels in follicular fluid differ between these different types of follicles, we measured IGFBP levels in fluids from these follicles. A total of 61 follicles were assessed by light microscopy and characterized by morphological analysis as either healthy, with columnar or rounded basal granulosa cells, or as undergoing antral or basal atresia. The IGFBP concentration in the follicular fluid of individual follicles from the four groups (n = 12-20 per group) was identified by Western ligand blots using (125)I-insulin-like growth factor (IGF)-II as a probe. Insulin-like growth factor binding proteins 2, 3 (44 and 40 kDa), 4 (glycosylated and non-glycosylated) and 5 were observed. The levels (per volume of fluid) of IGFBPs 2, 4 and 5 were greater in atretic follicles than in healthy follicles. However, there were no statistical differences in levels of each IGFBP between either the two types of healthy follicle or between the two types of atretic follicles. Thus, IGFBP levels are not related to the different types of healthy or atretic follicles.

Vascularity and expression of angiogenic factors in bovine dominant follicles of the first follicular wave1

To determine the relationships among vascularity, expression of angiogenic factors, and selected intrafollicular factors in dominant and nondominant follicles of the first follicular wave, ovaries were obtained on d 3 of the estrous cycle from mature cross-bred beef heifers (n = 8) after a synchronized estrus. Follicular fluid (FF) was collected from all follicles > or = 3 mm for determination of estradiol-17beta (E), progesterone (P4), vascular endothelial growth factor (VEGF), and IGFBP concentrations. The ovaries were then perfusion-fixed and used for histochemical detection of lectin BS-1 (a marker of endothelial cells and thus vascularization) binding, and immunolocalization of VEGF, endothelial nitric oxide synthase (eNOS), and proliferating cell nuclear antigen, followed by image analysis of selected follicles. Follicles were classified, based on E and P4 concentrations in FF, as dominant, estrogen-active (EA; E:P4 > or = 1) or nondominant, estrogen-inactive (EI; E:P4 <1). Concentrations of E and VEGF in FF, the area of positive staining for lectin BS-1, VEGF, and eNOS, and the labeling index (an index of the percentage of cells proliferating) in granulosa and theca layers were greater (P < 0.05) in the EA than in the EI follicles, but concentrations of P4 and IGFBP in FF were less (P < 0.05) in EA than in EI follicles. In addition, vascularity was positively correlated (P < 0.05) with VEGF and eNOS protein expression, and tended (P < 0.1) to be positively correlated with the E:P4 ratio in FF but tended (P < 0.1) to be negatively correlated with IGFBP and P4 concentrations in FF. These data highlight the importance of vascularity, angiogenic factors, and IGFBP in the health of the dominant follicle in heifers, and indicate that the FF concentrations of E, VEGF, IGFBP, and P4, and the E:P4 ratio can be used as markers of dominant follicles.

Differential Expression and Prognostic Implications of the CCN Family Members WISP-1, WISP-2, and WISP-3 in Human Breast Cancer

BACKGROUND

The CCN family has three Wnt-inducted secreted proteins named WISP-1, WISP-2 and WISP-3. These molecules are known to play a diverse role in cells, but their role in cancer cells remains controversial.

METHODS

In this study, we analyzed the expression of the three WISP molecules at the mRNA and protein levels in a cohort of 122 human breast tumors and 32 normal breast tissues, and we correlated these findings with patients' clinical outcomes.

RESULTS

WISP-1 transcripts were found in lower levels in node-positive tumors compared with node-negative tumors (P < .05); were lower in patients with a moderate (P = .01) and poor Nottingham Prognostic Index prognosis (P < .05) compared with good prognostic groups; were of significantly lower level in grade 3 differentiated tumors (P < .05) compared with grade 1; and were of lower levels in patients who developed metastasis and died from breast cancer-related causes (P < .05 in both comparisons). Almost the reverse was found to be true for WISP-2, which had greater levels of expression in node-positive tumors (P = .0043); higher levels in both moderate and poor prognostic groups compared with the good prognostic group (both P < .05); greater level in both grade 2 and 3 when compared with grade 1 (both P < .05); and higher levels in patients who went on to develop metastases (P < .01). WISP-3 transcript levels showed no statistically significant differences between groups.

CONCLUSIONS

WISPs may play important but contrasting roles in breast cancer. WISP-1 seems to act as a tumor suppressor and WISP-2 as a factor that stimulates aggressiveness; WISP-3 has no definable beneficial or detrimental role.

IGFBP7 plays a potential tumor suppressor role in colorectal carcinogenesis

Insulin-like growth factor binding protein-7 (IGFBP7) is a gene identified as being low expressed in colorectal adenocarcinoma (CRC) cell lines. In the current study, we investigated the function of IGFBP7 in CRC by transfection studies. We found that IGFBP7 could inhibit cell growth, decrease soft agar colony formation activity and induce apoptosis in RKO and SW620 cells. Correlation analysis between the expression of IGFBP7 in CRC tissue and the prognosis in 218 patients showed that high expression of IGFBP7 was associated with favorable prognosis. Based on above results, we conclude that IGFBP7 plays a potential tumor suppressor role in colorectal carcinogenesis.

Insulin-like growth factors and binding proteins in early milk from mothers of preterm and term infants

Breast-fed preterm infants often show a better outcome, partly ascribed to the benefit of insulin-like growth factors (IGFs) and their binding proteins (IGFBP). We compared IGF-I, IGF-II, IGFBP-2 and IGFBP-3 levels, measured by radioimmunoassays in milk samples from 30 mothers of preterm (<31 weeks) and from 19 mothers of term (>37 weeks) infants at days 7 and 21 postpartum. Proteolysis of IGFBP-2 within mother's milk and digestion of (125)I-IGF-II and (125)I-IGFBP-2 by gastric juice from neonates were assessed by electrophoretic techniques. Mean concentrations did not differ between preterm and term milk: IGF-I (2.8 +/- 0.2 vs. 2.3 +/- 0.1 ng/ml), IGF-II (12.0 +/- 0.4 vs. 12.2 +/- 0.5 ng/ml), IGFBP-3 (100.0 +/- 5.1 vs. 80.0 +/- 5.8 ng/ml), but did so for IGFBP-2 (3,144 +/- 172 vs. 2,428 +/- 188 ng/ml, p < 0.02). Immunoblots revealed 42% (p < 0.05) more IGFBP-2 fragments of 14 and 25 kDa in preterm milk. Incubation with gastric juice caused cleavage of (125)I-IGFBP-2 and partial cleavage of (125)I-IGF-II. Mutual complexation protected IGF-II and IGFBP-2 from cleavage, suggesting that both are likely to arrive in the bowel in an intact form to exert promotive effects. The results provide further evidence that IGFBP-2 and IGF-II in breast milk are relevant factors for the early development of preterm infants.

Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) has potential tumour-suppressive activity in human lung cancer

The expression of insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) is decreased in various tumours, but the role of IGFBP-rP1 in lung cancer is not yet clear. In this study, IGFBP-rP1 expression in lung cancer cell lines was evaluated and reduced expression of IGFBP-rP1 was found. In tissue microarrays containing 138 primary tumours and 20 normal lung tissues analysed by immunohistochemistry, 58 tumours (42%) exhibited no expression of IGFBP-rP1, while all 20 normal lung tissues showed high expression. In squamous cell lung cancer, low expression of IGFBP-rP1 was significantly linked to high-grade tumours. Treatment with 5-aza-2'-deoxycytidine restored the expression of IGFBP-rP1 in three of four lung cancer cell lines. Sequencing of PCR products of sodium bisulphite-treated genomic DNA from the three lung cancer cell lines revealed a heterogeneous methylation pattern in the region of exon 1 and intron 1. Stable transfection of IGFBP-rP1 full-length cDNA into the H2170 lung cancer cell line led to increased expression of IGFBP-rP1 protein. IGFBP-rP1-positive transfectants exhibited remarkably reduced colony-forming ability in soft agar, suppression of tumour growth rate in nude mice, and increased apoptotic cell number as well as activated caspase-3 expression level. The data suggest that IGFBP-rP1 is a tumour suppressor inactivated by DNA methylation in human lung cancer.

Wound healing process of a full-thickness skin wound model in rats

Using a rat full-thickness skin wound model, confocal laser scanning microscopy was carried out for examination of angiogenesis in granulation tissue formation. By semi-quantitation analysis with reverse transcription-polymerase chain reaction (RT-PCR), assessment was made of mRNA expression in the vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF). Immunohistological analysis was also made to determine the location of these factors in granulation tissue at the protein level. Comparison was made of the cytokines in granulation and angiogenesis. Chronic granulation tissue with advanced fibrosis could be clearly demonstrated by the inhibition of wound contraction and epithelialization. From the results of the present study, VEGF would appear quite closely involved in angiogenesis in granulation tissue formation and pericytes may possibly give rise to VEGF and have significant roles in angiogenesis even with inhibition of epithelialization. CTGF expression in parenchyma is considerable during granulation and thus possibly may be related to the progress of fibrosis.

Value of insulin-like growth factor system markers in the assessment of growth hormone status

Insulin-like growth factor-I (IGF-I) has been measured extensively in a variety of clinical settings. Total IGF-I frequently is used to assess the clinical impact of disorders of GH secretion and to monitor patients' response to therapy. It does not have sufficient precision to be used as a stand-alone test in the diagnosis of GH deficiency. Free IGF-I, IGF binding protein-3, or acid-labile subunit may provide useful information regarding GH secretion in specific conditions but are not superior to IGF-I for making the diagnosis of GH deficiency or acromegaly.

IGFBP-3 and IGFBP-10 (CYR61) up-regulation during the development of Barrett's oesophagus and associated oesophageal adenocarcinoma: potential biomarkers of disease risk

Dys-regulation of the insulin-like growth factor (IGF) system increases the risk of a number of malignancies. The aim of this study was to investigate the role of members of the IGF binding protein (IGFBP) superfamily in the development of oesophageal adenocarcinoma (EAC) and their possible use as markers of disease risk. Expression of IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 was assessed using Real-Time-polymerase chain reaction (PCR) and immunohistochemistry in oesophageal tissues from Barrett's oesophagus (BE) patients with and without associated EAC, and in control subjects. IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 mRNA levels were up-regulated in Barrett's (n=17) and tumour tissue of EAC patients (n=18) compared with normal tissue of control subjects without BE or EAC (n=18) (p<0.001). Over-expression of IGFBP-3 and IGFBP-10/CYR61 proteins was observed in Barrett's, dysplastic and tumour tissue of EAC cases (n=47 for IGFBP-10; n=39 for IGFBP-3) compared with adjacent normal epithelium (p<0.050). Notably, IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 expression in Barrett's tissue of EAC cases (n=17) was significantly (p<0.001) higher than in Barrett's tissue of BE patients with no sign of progression to cancer (n=15). Overall, the results suggest that members of the IGFBP superfamily are up-regulated during oesophageal carcinogenesis and merit further investigation as markers of EAC risk.

[Complex treatment of inflammatory breast cancer]

Inflammatory breast cancer represents 2-5% of all malignant breast lesions. Its rapid progression, the rather short medical history of the disease is unique and seems to be very typical. The combined modality treatment of inflammatory breast cancer is a special challenge for the medical oncologists. Preoperative chemotherapy is of great importance. After getting fair remission, surgery and radiotherapy should be delivered. With combined modality therapy the 5-year overall survival is about 50%. Knowing more pharmaco-genomic details on the disease and delivering new medicaments the effectiveness of the treatment will be further enhanced.

Local changes in the insulin-like growth factor system in human skeletal muscle assessed by microdialysis and arterio-venous differences technique

IGF-I plays a direct role in whole body glucose homeostasis primarily by stimulating skeletal muscle glucose uptake. IGF-I is also involved in exercise induced muscle hypertrophy. Knowledge regarding local changes in muscle IGF-I bioavailability and its regulation by IGFBPs at rest and during exercise is limited. We have therefore explored changes in total IGF-I levels as well as circulating IGFBP levels and their post-translational modifications over an exercising leg. For the first time we have determined IGF-I levels in exercising skeletal muscle microdialysate in an attempt to assess local IGF-I bioavailability. Eighteen healthy young men performed one legged knee-extension exercise during 45min. Blood samples were taken from the femoral artery and vein of the exercising leg. No significant differences between arterial and venous concentrations of total IGF-I or IGFBP-1 were detected over the leg at any time. IGF-I concentrations increased significantly during exercise in the artery but not in the vein. Total IGFBP-1 increased after exercise in both artery and vein. The increase in non-plus less phosphorylated forms of IGFBP-1 was less pronounced and did not reach statistical significance. The proportion of fragmented IGFBP-3 (IGFBP-3 proteolysis) assessed by Western immunoblotting did not change significantly during or after exercise. Although optimization and validation of IGF-I determinations in muscle microdialysate (md) will be required, our first results using this technique demonstrate a significant 2-fold increase in mdIGF-I collected during and after exercise. We conclude that determination of A-V-differences appears to be of limited value in the assessments of local muscle change in the IGF-system. A substantial release of IGF-I during short time is required to detect significant change in the large circulating store of IGF-I. We suggest that an optimized and validated microdialysis technique for determination of local IGF-I may be advantageous in future studies.

Circulating growth hormone binding protein levels and mononuclear cell growth hormone receptor expression in uremia

BACKGROUND

Resistance to growth hormone (GH) in end-stage renal disease (ESRD) causes growth retardation and muscle wasting. In humans, circulating GH binding protein (GHBP), the extracellular domain of the GH receptor that is shed into the circulation and is believed to reflect tissue GH receptor levels, is reduced in uremia and suggests that cellular GH receptor levels are correspondingly reduced. If true, this could be a cause of GH resistance. We set out to establish whether serum GHBP levels reflect cellular GH receptor levels and whether changes in serum GHBP levels are related to nutritional or inflammatory status.

METHODS

GH receptor protein expression in peripheral blood mononuclear cells (PBMC) from 21 ESRD and 14 normal subjects were analyzed by fluorochrome flow cytometry.

RESULTS

The GH receptor density and percent total PBMCs expressing the GH receptor were similar in the 2 groups, and there was no difference in percent GH receptor positive T or B cells or monocytes. In contrast, serum GHBP levels were 80% lower in ESRD. GHBP levels did not correlate with serum albumin, body mass index, or muscle mass but seemed to be partly related to the log serum C-reactive protein levels.

CONCLUSIONS

Serum GHBP levels are markedly reduced in ESRD; this seems to occur independent of nutritional status and may in part be caused by inflammation. Because GH receptor expression on PBMC of ESRD and control subjects was similar, our findings argue against a reduction in GH receptor as a cause of GH resistance and the use of serum GHBP levels as a reliable marker of specific tissue GH receptor levels.

Immunohistochemical localization of components of the insulin-like growth factor system in human permanent teeth

There is growing evidence that the insulin-like growth factor (IGF) system plays an important role in the biology of oro-dento-facial tissues and organs, including the development, homeostasis and regeneration of the periodontium. To obtain basic data on the occurrence and distribution of IGF components in human permanent teeth we immunohistochemically investigated 25 extracted, decalcified and paraffin-embedded teeth using mono and polyclonal antibodies against the ligands IGF-I and -II, the IGF1 receptor (IGF1R) and all six IGF binding proteins (IGFBP-1 to -6). In the extracellular matrix (ECM) of the adhering periodontal ligament (PDL), immunoreactivity for IGF-I, -II and IGFBP-1 and -6 was observed. PDL fibroblasts showed immunostaining for the IGF1R. For the cementum, in the acellular cementum only IGF-II could be detected, while outer cementum layers with inserting Sharpey's fibers reacted with all antibodies applied except for IGFBP-4 and -6. In the pulp, mainly fibrotic areas and areas around denticles were immunoreactive for IGF-I, IGFBP-1, -3, -5 and -6. Predentin and odontoblastic processes were stained for IGF-I and IGFBP-3. The spatially oriented occurrence of components of the IGF system in human permanent teeth indicates that specific functions of the IGFs may be localized in particular tissue compartments. In the cementum, several IGF components were found indicating roles in tissue homeostasis or attachment. The PDL may function as a reservoir for IGFs probably bound to ECM components. PDL fibroblasts could then respond in a paracrine manner. In the pulp, the IGF system may be involved in odontoblast biology, fibrosis and denticle formation.

Alterations in follicular IGFBP mRNA expression and follicular fluid IGFBP concentrations during the first follicle wave in beef heifers

The objective was to determine the pattern of IGFBP-2, -3 and -4 gene expression and follicular fluid concentrations of IGFBP-2, -3, -4 and -5 during emergence, selection and dominance of the first follicle wave of the estrous cycle in cattle and during exogenous steroid treatment. Heifers (n = 35) were ovariectomized at 36 (n = 7), 66 (n = 8), 84 (n = 12) and 108 (n = 8) h after the onset of estrus. Heifers in the 84 h ovariectomy group were sub-divided to receive either no treatment (n = 6) or were treated with a progesterone-releasing intravaginal device (n = 6, PRID) and 0.75 mg estradiol benzoate i.m. at the approximate time of ovulation, 30 h post estrus until ovariectomy. Within heifers the four largest follicles recovered following ovariectomy were ranked on size (F1, F2, F3 and F4). At 36 h IGFBP gene expression and follicular fluid IGFBP concentrations were similar in all follicles (F1-F4). Mean diameter of the F1 follicle increased (P < 0.05) between 36 and 84 h with no difference between 84 and 108 h. The F1 follicle had the highest (P < 0.05) concentration of estradiol compared with the F2, F3 and F4 at 84 and 108 h. There was no granulosa cell IGFBP-2 mRNA in F1 follicles at 84 or 108 h. Intrafolliclar IGFBP-2 concentrations were lower (P < 0.05) in the F1 compared with F3 and F4 follicles at 108 h. There was no difference in theca cell IGFBP-4 mRNA expression at 108h, but amounts of follicular fluid IGFBP-4 were lower (P < 0.05) in F1 follicles compared with F3 and F4 follicles at 108 h. IGFBP-3 mRNA was localized in the theca layer of all follicles examined with no difference in expression or follicular fluid concentrations during emergence, selection and dominance of the first follicle wave. IGFBP-5 concentrations were higher (P < 0.05) in follicular fluid of F3 follicles at 108 h compared with the F3 at 36 h. In conclusion follicular dominance was associated with low or decreased follicular fluid concentrations of IGFBP-4 and -5, increased estradiol and differential regulation of IGFBP production.

The value of the insulin-like growth factor binding protein-1 in the cervical–vaginal secretion detected by immunochromatographic dipstick test in the prediction of delivery in women with clinically unconfirmed preterm premature rupture of membranes

OBJECTIVE

The aim of this study was to determine the value of detecting insulin-like growth factor binding protein-1 (IGFBP-1) in the cervical-vaginal secretion in the prediction of delivery in women with clinically uncorfirmed preterm premature rupture of membranes (PPROM).

MATERIAL AND METHODS

A total of 87 women, gestational age between 20 and 36 weeks were enrolled into this prospective study. Based on the clinical diagnosis, patients were grouped as clinically evident PPROM (n = 25), clinically suspected PPROM (n = 42) and women with intact fetal membranes (n = 20). Detection of IGFBP-1 in the cervical-vaginal secretions was done using a one-step immunochromatographic dipstick test in all women. The outcome measures were gestational age at delivery, neonatal birth weight and duration of the interval between the test and delivery between women with positive and negative test results.

RESULTS

The test was positive in all 25 women (100% sensitivity) with clinically evident PPROM and all delivered prematurely, and negative in 19 out of the 20 (95% specificity) women with intact fetal membranes. Among 36 women with clinically suspected PPROM, 13 (36%) tested positive and 23 (63%) tested negative for IGFBP-1. In this group, the mean gestational age and birth weight at the time of delivery were significantly lower in patients with positive test (31.38+/-2.6 weeks versus 38.61+/-0.99 weeks and 1761+/-527g versus 3500+/-355g, P < 0.05 for both). Eleven (85%) of the 13 women with positive test, delivered within 2 weeks after the performance of the test whereas all the women with negative test results delivered after 2 weeks (P = 0.001). The test had 100, 92, 84 and 100% sensitivity, specificity, positive predictive value and negative predictive value, respectively, for the outcome measure of test-delivery interval.

CONCLUSION

The screening test for IGFBP-1 in the cervical-vaginal secretions is a useful adjunct in the prediction of delivery in women with clinically unconfirmed PPROM.

IGF-I differentially regulates IGF-binding protein expression in primary mammary fibroblasts and epithelial cells

Elucidating how mitogens facilitate epithelial/stromal interactions is critical given that mitogens regulate mammary gland development and function. IGF-I is a potent mammary cell mitogen that is locally produced in the mammary gland. Since IGF-binding proteins (IGFBPs) regulate IGF-I bioavailability, we characterized the cell-type-specific production of IGFBP in primary bovine mammary epithelial (BME) and fibroblast (BMF) cells. Cells were treated with IGF-I and mRNA levels were analyzed via quantitative real-time (qRT)-PCR and Northern blot analysis. Media conditioned by cells treated with IGF-I for 48 h were analyzed via ligand blotting with 125I-labeled IGF-I and -II and immunoblotting with specific IGFBP antibodies. A reciprocal regulation of IGFBP-3 and -5 by IGF-I was observed between the two cell types. IGF-I induced large dose-dependent increases in IGFBP-3 mRNA and protein levels in BME cells, while IGFBP-5 protein was barely detectable and mRNA levels were detectable only by qRT-PCR. In BMFs, IGF-I induced large increases in IGFBP-5 mRNA and protein while IGFBP-3 mRNA was only slightly increased by IGF-I treatment and the protein was difficult to detect. IGFBP-6 mRNA was detected by Northern blot analysis in both cell types but was not regulated by IGF-I. In BME cells, IGFBP-6 protein levels were readily detectable under basal conditions and were increased by IGF-I. Interestingly, IGFBP-6 protein could not be detected in media conditioned by BMFs. IGFBP-4 mRNA was readily seen by Northern blot analysis in BMFs, however qRT-PCR was required to detect IGFBP-4 mRNA in BME cells. IGF-I increased IGFBP-4 mRNA levels by 2-fold in both cell types. IGFBP-4 protein was only detectable in media conditioned by BME cells when stimulated by IGF-I. In contrast, IGFBP-4 was present in media conditioned by untreated BMFs but was not consistently increased by IGF-I treatment. This was explained by the finding that IGF-I stimulated proteolysis of IGFBP-4, as evidenced by the appearance of two immuno-responsive fragments of 18 and 14 kDa. This proteolysis was specific to IGFBP-4, and was not observed in BME cells. We confirmed the protease to be pregnancy-associated plasma protein A (PAPP-A) by immunoblotting with an antibody against human PAPP-A/proMBP (pro form of eosinophil major basic protein) complex. In vitro immuno-neutralization experiments showed that blocking PAPP-A prevented the ability of IGF-I to stimulate IGFBP-4 proteolysis. IGFBP-2 mRNA and protein levels were observed under basal conditions in both cell types, with no significant regulation by IGF-I. The analysis of cell-type-specific regulation of the IGF system in both primary mammary epithelial cells and stromal cells will assist in the characterization of the mechanisms behind the role of the IGF system in normal mammary physiology and ultimately breast cancer.

Low IGF-I in synovial fluid and serum in patients with aseptic prosthesis loosening

BACKGROUND

We have previously shown that proliferation in primary cultures of human osteoblast-like cells is lower after exposure to synovial fluid from patients with aseptic prosthesis loosening than after exposure to synovial fluid from patients with osteoarthrosis.

MATERIALS AND METHODS

Insulin-like growth factors (IGF) I and II and IGF binding proteins (IGFBP) 3-6, were measured with radioimmunoassy in synovial fluid and in serum from patients with aseptic prosthesis loosening or osteoarthrosis. Proliferation in osteoblast-like MG-63 cells was studied with the CyQUANT assay.

RESULTS

IGF-I and IGFBP-4 concentrations were lower whereas the concentration of IGFBP-6 was higher in synovial fluids from patients with prosthesis loosening than in synovial fluid from patients with osteoarthrosis. IGF-I concentrations in serum from patients with prosthesis loosening were also lower than in the osteoarthrosis group, and were even below the normal range in most cases (72%). Synovial fluid from patients with aseptic loosening had a weaker stimulatory effect on MG63 osteoblast-like cell proliferation than synovial fluid from patients with osteoarthrosis, but there was no difference between the two groups when a human IGF-I antibody was added.

INTERPRETATION

Low levels of IGF-I in synovial fluid possibly result from low serum levels and may be a mechanism leading to aseptic prosthesis loosening.

Enhanced expression of insulin-like growth factor-binding proteins in human osteoarthritic cartilage detected by immunohistochemistry and in situ hybridization

OBJECTIVE

To determine the roles of insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) in the pathogenesis of osteoarthritis (OA).

DESIGN

Cartilage tissues were obtained from the femoral heads of patients with OA, and those from patients with femoral neck fractures were used as a control. The expression of IGFBP-3, -4, and -5 was examined using immunohistochemistry and in situ hybridization, and IGF-I and IGF-I receptors were also immunohistochemically detected. The percentages of positive chondrocytes were determined by counting the total number of chondrocytes over the area of the surface, middle, and deep zones of the cartilage.

RESULTS

There was a marked increase in the percentage of positive chondrocytes in all IGFBPs on protein and messenger RNA levels for OA compared to that of the control cartilage. Furthermore, enhanced expression of IGFBPs and the IGF-I/IGF-I receptor was positively correlated with the histologic score for cartilage lesions.

CONCLUSION

Up-regulation of IGFBPs as well as IGF-I and its receptor was observed for OA cartilage tissue, suggesting the involvement of IGFBPs in the pathogenesis of OA.

Altered expression of IGFs and IGF-binding proteins during intrauterine growth restriction in guinea pigs

The IGF system is one of the most important endocrine and paracrine growth factor systems that regulate fetal and placental growth. We hypothesized that intrauterine growth restriction (IUGR) in guinea pigs is mediated by the altered expression of IGFs and/or IGF binding protein (BP) mRNAs in tissues and is related to growth of specific tissues. IUGR was induced by unilateral uterine artery ligation on day 30 of gestation, and fetal plasma, amniotic fluid and tissue samples were collected at 55-57 days (term about 68 days) from paired IUGR and control fetuses (n=6). Western ligand blotting and immunoblotting were used to compare IGFBP levels in plasma and amniotic fluid. Total RNA was extracted from placenta and fetal tissues, and the relative abundance of IGF-II and IGFBP-1-6 mRNA was determined by Northern blotting, using species-specific probes where available. IUGR fetuses had decreased (P<0.01, by Student's t-test) placental weight and body weight with an increase in the brain:liver weight ratio. The principal IGFBPs in fetal plasma migrated at 40-35, 30 and 25 kDa and were identified as IGFBP-3, -2 and -4 respectively. IUGR was associated with elevated plasma IGFBP-2 and IGFBP-4 and reduced IGFBP-3 levels. IGFBPs were detected at low levels in amniotic fluid of control fetuses but at higher levels in IUGR fetuses. In IUGR placentae, there was a small increase in IGFBP-4 mRNA (P<0.05). IGFBP-2 mRNA increased (P<0.001) in liver of IUGR fetuses. IGF-II and IGFBP mRNA expression did not change in fetal muscle. The results are consistent with reduced IGF action, directly or through inhibition by IGFBPs, particularly by circulating and tissue IGFBP-2, as a potential causal factor in decreased growth of the placenta and certain fetal tissues.

Distribution of components of the insulin-like growth factor system in the temporomandibular joint of the aging mouse

The temporomandibular joint (TMJ) is a exceptional joint involved in growth as well as mastication. In adult mice, it provides a model for age related natural osteoarthritis (OA). The insulin-like growth factor (IGF-) system plays was tested because it plays important roles in cartilage biology and OA pathogenesis. Decalcified and paraffin embedded TMJs of 48 NMRI mice sacrificed in groups of three male and females each at the ages of 3, 4, 5, 7, 9, 10, 12, and 18 months were prepared for histopathology and immunohistochemistry for IGF-I and -II, IGF1 receptor and IGF binding proteins -1, -2, -3, -4, -5, and -6. Histopathological signs of OA were obvious in the TMJ of all animals older than 5 months, but did not show a clear age-related staging. Immunoreactivity for all IGF components was found in unchanged anterior and posterior regions of the condyle and in regions of advanced OA lesions. Receptor immunostaining was obvious in all ages. Most IGFBPs showed immunostaining patterns similar to IGFs. While the anterior and posterior zones of the condylar cartilage appear to be specialized judging by structure and IGF immunostaining pattern, probably due to metabolic or biomechanical peculiarities, the central portion undergoes early degeneration. In advanced OA stages, the IGF system seems to be upregulated to induce repair processes. According to their mainly inhibiting functions, IGFBPs may suppress anabolic IGF activities.

Effects of diet consistency on the expression of insulin-like growth factors (IGFs), IGF receptors and IGF binding proteins during the development of rat masseter muscle soon after weaning

A soft diet facilitates the development of faster-type fibres in rat masseter muscle in the 9 days after weaning compared with a hard diet. To determine whether insulin-like growth factors (IGFs), IGF receptors (IGFRs) and IGF binding proteins (IGFBPs) are involved in this fibre-type alteration, the expression of myosin heavy chain (MHC), IGF, IGFR and IGFBP mRNAs in the masseter muscle of rats fed a hard or soft diet for 9 days after weaning was analysed using competitive, reverse transcriptase-polymerase chain reaction. A soft diet decreased the expression of MHC IIa (slower type) by 70%, but increased the expression of MHC IIx (intermediate type) and IIb (faster type) by 80 and 582%, respectively, compared with a hard diet. These findings verified that a soft diet facilitates the development of faster-type fibres in rat masseter muscle compared with a hard diet. A soft diet induced reductions of 25-76% (P < 0.05-0.01) in the expression of IGF-I, IGF-II, IGFR2, IGFBP4 and IGFBP6 compared with a hard diet, but induced a 25% (P < 0.05) increase only in expression of IGFBP3. These findings suggest that the changes in expression of IGF-I, IGF-II, IGFR2, IGFBP3, IGFBP4 and IGFBP6 are associated with the fibre-type alteration of rat masseter muscle in response to diet consistency soon after weaning.

Metalloproteinases, insulin-like growth factor-I and its binding proteins in aortic aneurysm

Abdominal aortic aneurysm is accompanied by the impairment of collagen metabolism in arterial wall. Metalloproteinases and collagen-stimulating factors play an important role in the maintenance of balance between collagen biosynthesis and degradation in tissues. Insulin-like growth factor-I (IGF-I) plays a major role in the stimulation of collagen biosynthesis. Its activity and bioavailability to target cells are modulated by IGF binding proteins (IGFBPs). The potential role of these factors in the mechanism of collagen metabolism deregulation in aortic aneurysm is the purpose of this study. Therefore, we have compared the content of collagen, gelatinolytic activity, IGF-I, IGFBP-1 and IGFBP-3 in normal human aorta and aortic aneurysm. The content of hydroxyproline (representing collagen content) in the proteins of aortic aneurysm was found to be similar to that found in normal aorta. Taking into account that some of the hydroxyproline may be derived from collagen degradation products (CDPs), they were separated and hydroxyproline was determined. It has been found that CDP-derived hydroxyproline content in aortic aneurysm was increased as compared with normal aorta, suggesting an increased collagen degradation. In contrast, zymography showed a decrease of collagenolytic activity in aortic aneurysm tissue, but an increase in mural thrombus, compared to respective controls. IGF-I concentration in aortic aneurysm was decreased, while the concentrations of BP-1 and BP-3 were both increased compared to control. The data suggest that increased collagen degradation in aortic aneurysm is due to the increase in collagenolytic activity in mural thrombus accompanying aneurysm tissue. It suggests that the mural thrombus may play a critical role in the pathogenesis of abdominal aortic aneurysm.

A potentially deleterious role of IGFBP-2 on bone density in aging men and women

The role of the IGFs and IGFBPs on age-related changes in BMD in adult men and women is not well understood. Studying an age-stratified community based sample of 344 men and 276 women, we found higher IGFBP-2 levels to be associated with lower BMD. IGFBP-2, which increases with age in both men and women, was the strongest, most consistent predictor of BMD among the IGF/IGFBPs studied.

INTRODUCTION

Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are important regulators of tissue growth and metabolism, but their association with BMD in adult men and women is controversial.

MATERIALS AND METHODS

In an age-stratified, random sample of the community population, we examined the role of serum levels of IGF-I, IGF-II, and IGFBP-1, -2, and -3 on BMD of the proximal femur (total hip), lateral spine, midshaft, and ultradistal radius as measured by DXA. We explored the association before and after adjustment for potential confounders, including age, bioavailable estradiol and testosterone, sex hormone binding globulin (SHBG), and measures of total fat and skeletal muscle mass.

RESULTS

We studied 344 men (age, 23-90 years) and 276 women (age, 21-93 years; 166 postmenopausal) not on hormone replacement or oral contraceptives. In both men and women, IGF-I and IGFBP-3 levels fell with advancing age, whereas IGFBP-2 levels tended to rise with age. There was an inverse association of IGFBP-2 with BMD at most skeletal sites in men and both premenopausal and postmenopausal women, whereas lower IGF-I and IGFBP-3 were associated with lower BMD in men and postmenopausal women only. Lower IGF-II was associated with lower BMD in men only. There were no associations between IGFBP-1 and BMD in either sex. After adjustment for age, in most cases, we found no further associations between IGF-I, IGF-II, or IGFBP-3 and BMD. In contrast, after age adjustment, higher IGFBP-2 remained a predictor of lower BMD in men and postmenopausal women at all sites except for the lateral spine (for men: r = -0.21, -0.20, and -0.19, all p < 0.001; and for postmenopausal women: r = -0.34, -0.24, and -0.25, all p < 0.01, for the total hip, midshaft, and ultradistal radius, respectively). IGFBP-2 remained an independent negative predictor of BMD in men, postmenopausal women, and all women combined after additional adjustment for bioavailable sex steroids, but not at all sites after adjustment for SHBG and muscle mass. In premenopausal women, IGFBP-2 had similar associations as seen in postmenopausal women, but they were weaker and not statistically robust.

CONCLUSIONS

Among the IGF/IGFBPs in our study, IGFBP-2 was a key negative predictor of BMD among men and women, particularly postmenopausal women. Our findings suggest a potential role of the IGF/IGFBP system in regulating bone loss in aging men and women and identify a previously under-recognized, potentially deleterious role for IGFBP-2, a known inhibitor of IGF action that increases with age in both sexes. Whether the action of the IGF/IGFBP system on bone metabolism is mediated partly through its effects on muscle mass or SHBG deserves further study.

Expression of the insulin-like growth factor binding proteins during postnatal development of the murine mammary gland

IGF-I and IGF-II have known roles in postnatal development of the mammary gland. In contrast, the function of the high-affinity IGF binding proteins (IGFBPs) in mammary growth and differentiation is largely unknown. The goal of these studies was to determine the patterns and levels of IGFBP expression during postnatal growth of the murine mammary gland. IGFBP-1 to -5 proteins were detected in mammary tissue by immunoblotting during both pubertal and pregnancy-induced growth; however, the regulation of each IGFBP was distinct through these developmental periods. IGFBP-2 to -5 mRNAs were readily detectable in the developing gland by in situ hybridization analyses but were expressed in distinct cellular sites. IGFBP-3 and -5 mRNAs were expressed in the developing epithelial structures and in isolated stromal cells during ductal growth and alveolar differentiation. In the terminal end buds (TEBs), IGFBP-3 mRNA expression was consistent with its localization in the cap cells, whereas IGFBP-5 was highly expressed in the body cells of the TEB. In contrast, IGFBP-2 and -4 mRNAs were expressed predominantly in stromal cells. IGFBP-2 mRNA was localized to restricted sites in the neck of the TEB and along the ductal structures, whereas IGFBP-4 mRNA was widely expressed in the stroma surrounding the epithelial structures. Protein and mRNA expression for most of the IGFBPs decreased during lactational ages. Levels of IGFBP-2 and -5 protein increased after pup removal during forced involution. Taken together, these data suggest important functions for the family of IGFBPs during postnatal growth and differentiation of the mammary epithelium.

Basal and stimulated levels of growth hormone, insulin-like growth factor-I (IGF-I), IGF-I binding and IGF-binding proteins in beta-thalassemia major

A significant percentage of children with beta-thalassemia major shows retardation in longitudinal growth as they progress towards puberty due to skeletal dysplasia, endocrine gland hypofunction or trace element deficiencies. The aim of this study was to evaluate GH/IGF-I secretion and action in prepubertal patients with beta-thalas-semia major. Eight prepubertal patients with short stature (group A) and seven prepubertal patients with normal stature (group B) were studied. Basal and stimulated (after administration of the hexapeptide Hexarelin) GH levels were measured with IRMA (Nichols); IGF-I and IGFBP-3 levels were measured with RIA (Nichols). IGF-I binding proteins (IGFBPs) were analyzed qualitatively with Western ligand blot. IGF-I binding to B-lymphocytes of the patients was also measured with competitive binding studies using human recombinant IGF-I and 125I-IGF-I (Amersham). Basal GH levels did not differ statistically between the groups. Peak GH levels after Hexarelin stimulation test were higher in group A (A: 27.9 +/- 15.6 ng/ml vs B: 9.1 +/- 4.7 ng/ml) (Wilcoxon test, p < 0.05). IGF-I levels in the two groups were low-normal and comparable (A: 168.0 +/- 81.6 ng/ml vs B: 126.6 +/- 25.5 ng/ml). IGFBP-3 levels were low in both groups (A: 1.21 +/- 0.27 microg/ml vs B: 1.08 +/- 0.20 microg/ml). Western ligand blot did not reveal any discernible difference in IGFBPs. However, IGF-I binding on B-lymphocytes was at least 20% lower in group A compared to group B (t-test, p < 0.01). IGF-I binding inversely correlated with peak GH levels (r = -0.54, p < 0.05). Patients in group A were older and chronological age correlated with IGF-I levels (r = 0.53, p < 0.05) whereas it inversely correlated with IGF-I binding (r = -0.63, p < 0.05). Moreover, patients in group A had higher ferritin levels. No correlation was found between ferritin levels, desferrioxamine dose/compliance or liver enzyme levels and the parameters of the GH axis studied. However, desferrioxamine dose x years correlated with IGFBP-3 (r = 0.56, p < 0.05) and correlated inversely with IGF-I binding (r = -0.74, p < 0.01). In conclusion, we have shown adequate GH secretion, higher secretive capacity after the administration of Hexarelin and lower IGF-I binding in prepubertal beta-thalassemic patients with short stature. Whatever the cause, reduced IGF-I action has to be considered when treating beta-thalassemic patients with short stature.

Isocaloric maternal low-protein diet alters IGF-I, IGFBPs, and hepatocyte proliferation in the fetal rat

We investigated the effect of an isocaloric maternal low-protein diet during pregnancy in rats on the proliferative capacity of cultured fetal hepatocytes. The potential roles of these changes on the IGF-IGF-binding protein (IGFBP) axis, and the role of insulin and glucocorticoids in liver growth retardation, were also evaluated. Pregnant Wistar rats were fed a control (C) diet (20% protein) or a low-protein (LP) diet (8%) throughout gestation. In primary culture, the DNA synthesis of hepatocytes derived from LP fetuses was decreased by approximately 30% compared with control hepatocytes (P < 0.05). In parallel, in vivo moderate protein restriction in the dam reduced the fetal liver weight and IGF-I level in fetal plasma (P < 0.01) and augmented the abundance of 29- to 32-kDa IGFBPs in fetal plasma (P < 0.01) and fetal liver (P < 0.01). By contrast, the abundance of IGF-II mRNA in liver of LP fetuses was unaffected by the LP diet. In vitro, the LP-derived hepatocytes produced less IGF-I (P < 0.01) and more 29- to 32-kDa IGFBPs (P < 0.01) than hepatocytes derived from control fetuses. These alterations still appeared after 3-4 days of culture, indicating some persistence in programming. Dexamethasone treatment of control-derived hepatocytes decreased cell proliferation (54 +/- 2.3%, P < 0.01) and stimulated 29- to 32-kDa IGFBPs, whereas insulin promoted fetal hepatocyte growth (127 +/- 5.5%, P < 0.01) and inhibited 29- to 32-kDa IGFBPs. These results show that liver growth and cell proliferation in association with IGF-I and IGFBP levels are affected in utero by fetal undernutrition. It also suggests that glucocorticoids and insulin may modulate these effects.