Analysis of bone mineral density and turnover in patients with cystic fibrosis: associations between the IGF system and inflammatory cytokines

BACKGROUND

Cystic fibrosis (CF) patients present an increased risk of osteoporosis, and increased fracture rate. Several factors have been identified as modulators of bone metabolism and bone mineral density (BMD).

AIMS

To evaluate BMD and serum markers of bone turnover and establish their relationships with serum concentrations of interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha, IGF-I, IGF-II, IGF binding protein (IGFBP)-2, IGFBP-3, and parathyroid hormone (PTH) in young adult CF patients.

METHODS

Seventeen young adult CF patients (4 M, 13 F; mean age: 26.6 +/- 1.1 years) were enrolled in the study and analysed as a whole and as two subgroups according to the Shwachman-Kulczycki score. BMD was assessed at the lumbar spine (L1-L4) by dual energy X-ray absorptiometry (DXA Hologic QDR 2000). Bone turnover was assessed by measuring serum levels of osteocalcin (OC) and serum carboxyterminal propeptide of type I collagen (PICP) as markers of bone formation, and serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) as a marker of bone resorption. Serum IGFs, IGFBPs, and cytokines were assayed using special commercial kits. Daily calcium intake and weekly physical activity were estimated by questionnaires. Forced expiratory volume in one second was used to assess pulmonary function.

RESULTS

Lumbar BMD was normal, although there was a tendency to be lower in the patients with a lower clinical score. Both OC and PICP were increased, whereas ICTP was normal. Lumbar BMD was positively correlated with pulmonary function. IL-6 and C-reactive protein (markers of inflammation) were inversely correlated with PICP. Serum ICTP levels were correlated with serum IGF-I levels. No significant relationship was detected among lumbar BMD, markers of bone turnover and PTH, IGF-I, IGF-II, IGFBP-2, IGFBP-3, TNF-alpha, IL-1beta, and body mass index Z-score.

CONCLUSIONS

Bone turnover is abnormal in CF patients. Young adult CF patients with satisfying clinical status and nutritional conditions have normal BMD and increased serum OC and PICP levels.

Gap analysis of pediatric reference intervals related to thyroid hormones and the growth hormone–insulin growth factor axis

Efficacy of laboratory medicine in assisting attending physicians in their diagnostic and follow-up endeavors is intimately linked to an access to meaningful and reliable reference values. Pediatrics is particularly sensitive to this problem as the processes, associated with growth and development, are imposing rapid discontinuous changes on the physiology of the individuals. Some developmental stages are more critical than others. The neonatal and the pubertal periods, for which we lack reference ranges, are two such examples. Beyond biological considerations, we realize that, over the last 2 decades, technology has evolved, both at the analytical and reagent levels. This technological evolution inexorably leads to the need in redefining reference values. It is for this reason that a group of clinical and medical biochemists have joined their efforts in creating the Canadian Laboratory Initiative in Paediatric Reference (CALIPER) which objective is to define a pan-Canadian set of reference values from birth to late adolescence. To illustrate the need of such a venture, a brief gap analysis for biochemical variables related to the thyroid function, and the growth hormone-insulin-like growth factors axis follows.

Hypopituitarism findings in patients with primary brain tumors 1 year after neurosurgical treatment: preliminary report

Hypopituitarism represents the consequence of many conditions, in both the adult and child population. It may occur after neurosurgical treatment of brain tumors arising near sella turcica. Much more attention has been focused on lesions far from the hypothalamic-pituitary region as possible causes of pituitary impairment, validating the concept of the particular fragility of these structures. The aim of this study was to evaluate pituitary function in particular GH deficiency (GHD) in patients submitted to neurosurgery for benign tumors of the central nervous system (CNS) not involving hypothalamic-pituitary region. We observed 37 patients with benign brain tumors [13 males, 24 females, age: 54.6+/-13.9 yr; body mass index (BMI): 25.1+/-4.0 kg/m2] performing a basic evaluation of the pituitary function and a dynamic test of the GH/IGF-I axis [GHRH (1 microg/kg iv)+arginine (0.5 g/kg iv) test] for 3 and 12 months after the neurosurgical treatment. Some degree of hypopituitarism was shown in 16 patients (43.2%) at the 3-months follow-up. Hypogonadism was present in 4 patients, hypoadrenalism in another 4 and hypothyroidism in 2. Two patients showed mild hyperprolactinemia and no patients had diabetes insipidus. Seven patients (18.9%) were GH deficient (peak GH <16.5 microg/dl). At 12 months retesting, some degree of hypopituitarism was confirmed in 8 patients, hypogonadism in 2 and hypothyroidism in one; no patients showed hypoadrenalism and GHD was present in 5. This data suggests that hypopituitarism of various degree may develop in patients who are submitted to neurosurgery for primary brain tumors, even far from hypothalamic-pituitary region.

Peripartum maternal and foetal ghrelin, growth hormones, IGFs and insulin interrelations

OBJECTIVE

Ghrelin may influence GH secretion and is associated with insulin sensitivity. In pregnancy, placental growth hormone (PGH) replaces GH. The aim of this study was to investigate the relationship between PGH and ghrelin and their relationship to insulin sensitivity in pregnancy.

DESIGN

Prospective, descriptive study.

PATIENTS

Thirty-seven singleton pregnant and six twin pregnant women

MEASUREMENTS

Maternal blood samples were drawn before and 2 days after elective caesarian section (CS). Serum total ghrelin, PGH, GH, GH-binding protein, insulin and IGF-I and IGF-II, and plasma glucose were determined. Insulin sensitivity indices (ISIs) were calculated. Cord blood samples were drawn at delivery for ghrelin determination.

RESULTS

Serum ghrelin only displayed a minimal, although statistically significant, decrease after CS. Prior to delivery serum PGH increased by 25% during fasting, and was undetectable the day after CS. Serum levels of GH were low until 48 h after CS. No significant correlations were detected between PGH or ghrelin and ISIs, although a trend was observed for ghrelin. Twin pregnancies had higher PGH levels than singletons; however, levels of IGFs were similar. In cord blood, ghrelin levels were higher in arterial than venous samples.

CONCLUSIONS

Maternal ghrelin levels were only minimally affected by parturition, suggesting that maternal ghrelin is not involved in the transition from PGH to GH secretion. The increased arterial ghrelin levels in the foetus suggest foetal ghrelin production. Serum PGH appears to be influenced by fasting. Finally, elevated PGH levels in twin pregnancies do not appear to affect maternal IGF levels.

Evaluation of the components of the insulin-like growth factors system in GH-deficient adults: effects of twelve-month rhGH treatment

The impact of GH deficiency and rhGH replacement therapy on IGF-I, IGFBP-3 and ALS levels has been widely studied. There is less information available on IGF-II levels, the component of the ternary complex poorly dependent on GH. We investigate the components of IGFs system in 36 GHD adults (28M, 8F, age 45 +/- 14 yrs) before and after 12 months of rhGH therapy (mean dose 0.3 +/- 0.1 mg/day). One-hundred healthy sex- and age-matched subjects were studied for comparison. At baseline, GHD patients showed IGF-I and IGF-II levels and IGFs to IGFBP-3 molar ratios that were lower than controls. During therapy, IGF-I levels increased (p < 0.01) to normal range. IGF-II levels, though higher than at baseline (p < 0.01), remained lower than in controls (p < 0.01). ALS and IGFBP-3 significantly increased (p < 0.001). These modifications resulted in normalization in IGF-I to IGFBP-3 ratio, while no change in IGF-II to IGFBP-3 ratio was observed. In conclusion, the increase of serum IGF-II levels during rhGH treatment in GHD patients probably reflects the increase in the other components of ternary complex (ALS and IGFBP-3). However, serum IGF-II levels as well as IGF-II to IGFBP-3 ratio, although increased, were definitely lower than in controls. This last result, given the increasing evidences of a direct implication of IGF-II in cancer, may further confirm the safety of rhGH replacement in adults with severe GHD as diagnosed by appropriate stimulation tests.

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.

The IGF system in a case of Costello syndrome

Costello syndrome is characterized by facial dysmorphia, hyperpigmented skin, palmar and plantar hyperkeratosis, curly hair, perioral and nasal papillomata (more rarely localized anally and on vocal cords), short stature, mental retardation and sociable personality. Although growth retardation is typical of Costello syndrome, its cause is not defined. We report on a 10-yr-old Caucasian girl affected by Costello syndrome with fasting hypoglycemia and short stature, associated low circulating levels of acid-labile subunit (ALS), relatively low levels of IGF-I and IGFBP-3, and normal IGF-II, mostly circulating in a binary complex with IGFBP-2 and -6 instead of in a 150 kDa ternary complex. The reduced ALS concentration and the consequent impaired formation of the circulating 150 kDa ternary complex can induce an accelerated clearance rate of IGF peptides and of IGFBP-3, contributing to the decreased IGF-I growth promoting activity in our patient. Moreover, the presence of IGF-II in the binary complex, which has been postulated to increase the insulin-like effects of these peptides, can explain, at least in part, the patient's asymptomatic fasting hypoglycemia.

Racial differences in premenopausal endogenous hormones

Differences in breast cancer incidence across racial groups are well documented. African Americans have the highest rates of premenopausal breast cancer and Asians have lower breast cancer rates across all age groups. We hypothesized that levels of premenopausal endogenous hormones and growth factors, risk factors that have been predictive of breast cancer, would differ by race. Using a cross-sectional study design, we tested this hypothesis in the Nurses' Health Study II. We assayed estradiol, progesterone, prolactin, sex hormone binding globulin (SHBG), insulin-like growth factor-I (IGF-I), and IGFBP-3 in 111 African American and 111 Asian American women, matched to 111 Caucasian women on age, day of luteal phase, and day, time, and fasting status at blood collection. We analyzed the association between race and hormone levels using robust linear regression methods. In multivariate models, compared with Caucasians, African Americans had 18% higher levels of estradiol (P < 0.01), 17% higher free estradiol (P < 0.01), 11% lower SHBG (P = 0.05), 11% higher IGF-I (P < 0.01), 25% higher free IGF-I (P < 0.01), and 9% lower IGFBP-3 (P < 0.01) levels. In multivariate models, compared with Caucasian women, Asian Americans had 22% higher calculated free estradiol (P < 0.01), 31% lower SHBG (P < 0.01), and 25% higher free IGF-I (P < 0.01) levels. No racial differences were found in progesterone and prolactin levels. Our study showed hormone differences consistent with breast cancer risk between Caucasians and African Americans but inconsistent with breast cancer risk between Asian Americans and Caucasians. Further research is needed to explore differences across racial groups and the link between endogenous hormones and breast cancer risk.

A prospective study of the insulin-like growth factor axis in relation with prostate cancer in the SU.VI.MAX trial

Several epidemiologic studies have examined with diverging results the relationships between circulating levels of insulin-like growth factors (IGF) and of IGF-binding proteins (IGFBP) and prostate cancer risk. We assessed the association of prediagnostic plasma levels of IGF-I, IGF-II, IGFBP-2, and IGFBP-3 and subsequent occurrence of prostate cancer in a case-control study nested in the SU.VI.MAX trial. The SU.VI.MAX study was a primary prevention trial testing a daily supplementation with low-dose antioxidant vitamins and minerals in male and female middle-aged volunteers in France. One hundred prostate cancer cases were diagnosed among 4,855 SU.VI.MAX participants over a 9-year follow-up period. For each case, four age-matched controls were selected randomly. Frozen baseline plasma samples were used to measure IGF-I, IGF-II, IGFBP-2, and IGFBP-3. Conditional logistic regression was used to assess the association between these four biochemical markers and prostate cancer risk. After controlling for the intervention group in the trial and the other IGF axis variables, the odds ratios and 95% confidence interval (95% CI) comparing the upper quartile to the baseline quartile were 1.83 (95% CI, 0.85-3.95), 1.05 (95% CI, 0.35-3.18), 0.79 (95% CI, 0.39-1.58), and 0.42 (95% CI, 0.12-1.52) for IGF-I, IGF-II, IGFBP-2, and IGFBP-3, respectively. More suggestive associations for IGF-I and IGFBP-3 were observed with advanced and aggressive cancers. Our results are consistent with those of some previous prospective studies and suggest that IGF axis variables are not long-term predictors of the occurrence of prostate cancer.

Insulin resistance, apoptosis, and colorectal adenoma risk

Compelling evidence from epidemiologic studies indicates that elevated circulating insulin-like growth factor (IGF)-I, insulin resistance, and associated complications, such as elevated fasting plasma insulin, glucose and free fatty acids, glucose intolerance, increased body mass index, and visceral adiposity, are linked with increased risk of colorectal cancer. However, the role of insulin and markers of glucose control in the development of adenomas, precursors to colorectal cancer, has not been fully explored. We evaluated the relationship between plasma insulin, glucose, IGF-I, IGF-II, IGF-binding protein-3 (IGFBP-3), apoptosis, and colorectal adenomas in a case-control study. Participants were drawn from consenting patients undergoing colonoscopy at the University of North Carolina hospitals (Chapel Hill, NC). Participants were classified as cases or controls based on whether they had one or more colorectal adenomatous polyps. Fasting plasma insulin, IGF-I, IGF-II, and IGFBP-3 levels were assessed by ELISA. Glucose was measured by glucose hexokinase assay. Apoptosis was assessed by morphology on H&E-stained sections. Dietary and lifestyle information were obtained by telephone interview. Logistic regression was used to examine the association between adenoma status and insulin-IGF markers. Adenoma cases (n = 239) and adenoma-free controls (n = 517) provided rectal biopsies and/or blood samples and interview data. Consistent with prior findings, cases were more likely to be males, older, have higher waist-to-hip ratio, lower calcium intake, lower apoptosis, and less likely to report nonsteroidal anti-inflammatory drug use. Those in the highest quartile of insulin (adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.2) and glucose (adjusted odds ratio, 1.8; 95% confidence interval, 0.9-3.6) were more likely to have an adenoma compared with the lowest quartile. Similarly, subjects in the highest two quartiles of insulin were more likely to be in the lowest two quartiles of apoptosis. Overall, there were no significant differences between mean circulating levels of glucose, IGF-I, IGF-II, and IGFBP-3 among cases and controls and no association between these variables and apoptosis. The results provide novel evidence that elevated insulin and glucose are associated with increased adenoma risk and decreased apoptosis in normal rectal mucosa. These findings suggest that insulin may act early in the adenoma-carcinoma sequence to promote the development of colorectal adenoma by decreasing apoptosis in the normal mucosa.

Erythropoietin administration does not influence the GH--IGF axis or makers of bone turnover in recreational athletes

OBJECTIVE

Measurement of biochemical markers of the IGF-system and of collagen turnover is a potential approach to detect GH abuse in sport. These markers are increased in patients on dialysis treated with recombinant human erythropoietin (r-HuEPO), mimicking the effects of GH. The aim was to determine whether r-HuEPO induces similar effects on the IGF-system and collagen turnover in healthy athletes.

SUBJECTS AND MEASUREMENTS

Young male Caucasian recreational athletes were administered 50 U/kg r-HuEPO (n=14) or placebo (n=16) three times a week for 25 days, followed by a 4-week wash-out period. IGF-I, IGFBP-3, the acid labile subunit (ALS), N-terminal propeptide of type I collagen (PINP), C-terminal telopeptide of type I collagen (ICTP) and N-terminal propeptide of type III collagen (PIIINP) were measured in samples collected at baseline (two samples), after 10, 22 and 24 days of r-HuEPO treatment and at the end of the 4-week wash-out period.

RESULTS

Treatment with r-HuEPO resulted in approximately threefold elevation of serum EPO and marked elevation of markers of erythropoiesis. There was no significant treatment effect of r-HuEPO compared to baseline on IGF-I, IGFBP-3, ALS, PINP, ICTP or PIIINP.

CONCLUSIONS

r-HuEPO administration did not change markers of the IGF-system and of collagen turnover in young healthy male athletes. Therefore, use of r-HuEPO in athletes should not affect the validity of a GH doping test using these GH-responsive markers.

[Maternal blood and amniotic fluid insulin-like growth factor detection and amniotic cavity drug delivery for early diagnosis and management of fetal growth restriction]

OBJECTIVE

To explore the relationship between insulin-like growth factors (IGFs) and fetal growth restriction (FGR) and early treatment of FGR.

METHODS

The levels of IGF-I and IGF-II were detected with radioimmunoassay in maternal blood and amniotic fluid samples of 44 pregnant women with FGR and 36 normal gravidas. The 44 gravidas with FGR were randomized into treatment group with amino acid by a pediatric administration to the amniotic cavity formula and control group with intravenous infusion of compound amino acid. The therapeutic effects were compared between the two groups on the basis of B-type ultrasound findings.

RESULTS

Maternal blood IGF-I and amniotic fluid IGF-I and IGF-II levels in the pregnant women with FGR were significantly lower than those in normal gravidas (P<0.01). After therapy, IGF-I and IGF-II levels were significantly increased in the treatment group (P<0.01), but no obvious changes in IGF-I and IGF-II levels were observed in the control group (P>0.05). Compared with the control group, IGF-I and IGF-II levels increased significantly in the amniotic fluid in the treatment group, with also marked elevation of IGF-I levels in maternal blood (P<0.01). Better therapeutic effects were achieved in the treatment group than in the control group (P<0.01), and the birth weights of the neonates in the treatment group were basically normal.

CONCLUSIONS

Detection of amniotic fluid IGF-I and IGF-II and maternal blood IGF-I can help predict the condition and facilitate early diagnosis of FGR. Injection of pediatric amino acid into the amniotic cavity can be effective for treatment of FGR.

Associations among circulating sex hormones, insulin-like growth factor, lipids, and mammographic density in postmenopausal women

OBJECTIVE

Hormone therapy use has been positively associated with mammographic density in several studies. However, few studies have examined the association between endogenous hormone levels and mammographic density. Therefore, we evaluated the relationship of endogenous sex hormones, insulin-like growth factor (IGF), and lipids with mammographic density in 88 overweight, postmenopausal women not taking hormone therapy.

METHODS

Percent density and dense area were evaluated as continuous measures using a computer-assisted program. We used multiple linear regression to evaluate the associations of sex hormones, IGF, and cholesterol with mammographic density, adjusting for confounders, including adiposity. We evaluated stratification by history of hormone therapy use (former versus never) and hormone therapy latency (<5 versus > or = 5 years).

RESULTS

Among former hormone therapy users, mammographic density was inversely associated with circulating levels of estrone (P = 0.01), estradiol (P = 0.003), free estradiol (P = 0.004), testosterone (P = 0.04), free testosterone (P = 0.02), androstenedione (P < 0.001), dehydroepiandrosterone (P = 0.01), and the ratio of IGF-I to its binding protein (IGF-I/IGFBP-3; P = 0.04). We found similar associations when we limited the analyses to women who had used hormone therapy within the past 5 years. We also noted positive associations of mammographic density with total cholesterol (P = 0.03) and low-density lipoprotein (P = 0.03) among former hormone therapy users. No associations were noted among women who had never used hormone therapy.

CONCLUSIONS

These results suggest that there is an inverse relationship between endogenous sex hormones and mammographic density in postmenopausal women among former users of hormone therapy. This is not consistent with the hormone therapy literature and should be confirmed in larger studies.

Circulating levels of insulin-like growth factors, their binding proteins, and breast cancer risk

BACKGROUND

Earlier data support the hypothesis that the relation between circulating insulin-like growth factor-I (IGF-I) levels and breast cancer risk differs by menopausal status. The strong association of IGF-I with height in childhood and weak or no association between adult levels and adult height also suggest that IGF levels in young women may better reflect an exposure time period of importance to breast cancer. Few studies have assessed IGF binding protein-1 (IGFBP-1) or free IGF and breast cancer risk.

MATERIALS AND METHODS

We conducted a large case-control study nested within the prospective Nurses' Health Study. Plasma concentrations of IGF-I, free IGF, IGFBP-3, and IGFBP-1 were measured in blood samples collected in 1989 to 1990. Eight hundred women were identified who had a diagnosis of invasive or in situ breast cancer after blood collection, up to 1998, 27% of whom were premenopausal at blood collection. To those 800 women, one to two controls were age-matched for a total of 1,129 controls. We used logistic regression models to estimate the relative risk (RR) of breast cancer associated with IGF levels.

FINDINGS

Among postmenopausal women, neither IGF-I, IGFBP-3, IGFBP-1, nor free IGF was associated with breast cancer risk [RRs, top versus bottom quintile: IGF-I, 1.0; 95% confidence interval (95% CI), 0.7-1.4; IGFBP-3, 0.8; 95% CI, 0.6-1.1; IGFBP-1, 0.9; 95% CI, 0.6-1.5; and free IGF, 1.0; 95% CI, 0.6-1.4]. Among premenopausal women, IGFBP-3, IGFBP-1, and free IGF similarly were not associated with breast cancer risk (RRs, top versus bottom quintile: IGFBP-3, 1.2; 95% CI, 0.8-2.3; IGFBP-1, 1.5; 95% CI, 0.8-3.0; and free IGF, 1.1; 95% CI, 0.7-2.1). Higher IGF-I plasma levels, however, were associated with a modestly elevated breast cancer risk (RR, 1.6; 95% CI, 1.0-2.6) among the premenopausal women, with a stronger association among premenopausal women ages < or =50 (RR, 2.5; 95% CI, 1.4-4.3); further adjustment for IGFBP-3 did not greatly change these estimates.

INTERPRETATION

Circulating IGF-I levels seem to be modestly associated with breast cancer risk among premenopausal women, but not among postmenopausal women. IGFBP-3, IGFBP-1, and free IGF are not associated with breast cancer risk in either premenopausal or postmenopausal women in this cohort.

Effects of an enhanced vitamin A intake during the dry period on retinoids, lactoferrin, IGF system, mammary gland epithelial cell apoptosis, and subsequent lactation in dairy cows

Studies in vitro show important interactions among vitamin A, lactoferrin, and insulin-like growth factor (IGF) binding proteins (IGFBP) and, thus, the IGF system. As a consequence, mammary gland epithelial cell proliferation and apoptosis during the bovine dry period and potential milk yield may be affected. We have studied effects of feeding vitamin A (550,000 IU/ d) that exceed daily requirements about 8-fold for up to 2 mo to dairy cows during the dry period on concentrations of retinol and its metabolites in plasma and milk, milk lactoferrin, plasma and milk IGF-I and IGFBP-3, lactoferrin and IGF-I mRNA levels in mammary gland tissue, mammary gland apoptosis, and 100-d milk yield in the ensuing lactation. In the group supplemented with vitamin A, the peripartal decrease of plasma retinol was delayed and attenuated, and colostral retinol plus retinylester concentration was enhanced, but colostral beta-carotene concentration decreased. The retinoic acid isomer 9,13-dicis retinoic acid that coeluted with 13-cis retinoic acid, was the predominant circulating retinoic acid and was higher in GrA than the control group. Plasma IGFBP-3 concentrations were positively correlated with plasma retinol concentrations (r = 0.51), but there were no group differences. Numbers of apoptotic epithelial cells in mammary epithelium were higher at drying off and parturition than in the middle of the dry period, coinciding with high concentrations of IGF-I and lactoferrin in mammary secretions. At parturition, numbers of apoptotic cells in mammary gland biopsies in cows supplemented with vitamin A were higher than in control cows. In conclusion, supplementation of dairy cows during the dry period with high amounts of vitamin A did not significantly modify concentrations of lactoferrin, IGFBP-3, and IGF-I in plasma and in mammary secretions, but slightly decreased energy-corrected 100-d milk yield and milk fat yield, possibly because of enhanced apoptic rates of mammary cells.

Insulin-like growth factors as diagnostic tools in growth hormone deficiency during childhood and adolescence: the KIGS experience

Growth hormone (GH) deficiency in children covers a spectrum of disorders involving an impairment in GH secretion and a clinical syndrome characterized by permanent stunting of growth. Ascertaining impairments in GH secretion directly is complex, especially if GH deficiency (GHD) is isolated and not caused by congenital or acquired pituitary defects or genetic abnormalities. It has been established that the concentrations of GH-dependent peptides, such as insulin-like growth factor I (IGF-I) and IGF-binding protein 3 (IGFBP-3), are low in patients with GHD. Their levels are, however, also influenced by a multitude of factors, such as age, gender, height, liver function, nutritional status and other hormones. In addition, the type of complex formed, e.g. either binary or ternary, may influence the measurements of IGFs and their binding proteins. Therefore, levels of IGF-I and IGFBP-3 are generally lower in short children compared with age-matched norms. The reported diagnostic value of sub-normal basal levels of IGF-I and IGFBP-3 is, in terms of sensitivity and specificity, approximately 70%. Thus, definite proof of GHD can only be achieved by means of GH measurements. As the diagnosis of GHD is somewhat unlikely if IGF testing shows normal values, it is clearly advantageous to schedule these tests as part of the initial diagnostic work-up in short children, as their implementation is not only practical but also inexpensive. The Pfizer International Growth Database (KIGS) analysis of IGF-I (n = 2,750) and IGFBP-3 (n = 1,300) levels in children with idiopathic GHD shows that these two parameters are now firmly embedded in diagnostic strategies around the world.

The IGF system in the neonatal ovine uterus

Postnatal development of the ovine uterus primarily involves uterine gland morphogenesis or adenogenesis. Adenogenesis involves the budding differentiation of the glandular epithelium (GE) from the luminal epithelium (LE) and then GE proliferation and coiling/branching morphogenetic development within the stroma between birth (postnatal day or PND 0) and PND 56. Insulin-like growth factor (IGF)-I and IGF-II mRNAs were previously found to be expressed only in the endometrial stroma, whereas the IGF receptor (IGF-1R) mRNA was most abundant in epithelia and in stroma, suggesting that an intrinsic IGF system regulates postnatal development of the uterus. Given that the biological activities of IGFs are modulated by a family of six IGF binding proteins (IGFBPs) and specific proteases, the objective was to determine the effects of age and estrogen disruption on expression of IGFs, IGFBPs and pregnancy-associated plasma protein A (PAPP-A or IGFBP-4 protease) in the ovine uterus. In Study One, circulating levels of IGF-I and IGF-II in the serum of neonatal ewes did not change between PND 0 and PND 56. Levels of immunoreactive IGF-I, IGF-II and IGF-1R protein were most abundant on the apical surface of the endometrial LE and GE. RT-PCR analyses detected expression of IGFBPs (3, 4, 5 and 6) as well as PAPP-A mRNAs in the uterus, but not IGFBP-1 and IGFBP-2 mRNAs. IGFBP-3 and IGFBP-4 mRNAs were expressed specifically in the endometrial stroma and myometrium and increased after birth. PAPP-A mRNA was expressed specifically in the endometrial stroma and increased after birth. In Study Two, ewes were treated from birth with estradiol-17beta valerate (EV), which reduces uterine growth and inhibits endometrial adenogenesis. On PNDs 14 and 56, IGFBP-3 mRNA was decreased in the uterus of EV-treated ewes, but IGF-1R and IGFBP-4 mRNAs were not affected. PAPP-A mRNA was increased by EV treatment on PND 14, but decreased on PND 56. These results support the hypothesis that an intrinsic IGF system in the uterus regulates epithelial-stromal interactions important for postnatal uterine growth and endometrial gland morphogenesis in the sheep.

Associations between Plasma Insulin-Like Growth Factor Proteins and C-Peptide and Quality of Life in Patients with Metastatic Colorectal Cancer

OBJECTIVE

Predictors of quality of life (QOL) in patients with metastatic colorectal cancer are lacking. The insulin-like growth factor (IGF) family of proteins is associated with QOL in noncancer populations. We sought to study whether these proteins are associated with QOL in patients with colorectal cancer.

METHOD

We used a cohort of 526 patients with metastatic colorectal cancer treated with combination chemotherapy. Plasma samples of IGF-I, IGF-II, IGF binding protein-3, and C-peptide were collected before initiation of chemotherapy. QOL was measured by the uniscale instrument and the Symptom Distress Scale at baseline and throughout treatment.

RESULTS

Baseline plasma levels of IGF-I and IGF-II before initiation of chemotherapy were significantly associated with several important baseline QOL measures in patients with metastatic colorectal cancer. Patients with lower levels of IGF-I reported increased distress with regard to appearance, appetite, cough, and nausea intensity after adjustment for potential confounders. Similarly, decreased levels of IGF-II were predictive of worse quality related to appearance, appetite, fatigue, nausea frequency and intensity, pain frequency, and composite Symptom Distress Scale score. IGF binding protein-3 and C-peptide were not predictive of baseline QOL. Baseline biomarkers were not associated with subsequent changes in QOL during treatment. Higher body mass index was significantly associated with superior baseline QOL in several areas; nonetheless, the association of IGF-I and IGF-II with baseline QOL measures remained significant even after controlling for baseline body mass index.

CONCLUSION

Baseline plasma IGF-I and IGF-II are significantly associated with symptom distress. Whether this association is simply reflective of patient nutritional status and/or disease burden or represents an independent biological effect of IGFs on QOL remains uncertain. Nonetheless, these data suggest that molecular biomarkers may be useful predictors of QOL in cancer patients.

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.

Growth impairment of primary chondrocyte cells by serum of rats with chronic renal failure

Insulin-like growth factor (IGF)/IGF binding protein (IGFBP) abnormalities may be important in the pathogenesis of growth failure in chronic renal failure (CRF). We induced experimental CRF by 5/6 nephrectomy in Sprague Dawley rats (100 g) and observed for 2 weeks comparing with sham-operated pair-fed control rats (Sham- C). CRF rats gained 30% less height than Sham- C rats (P < 0.01). Serum IGFBP profiles by Western ligand blot revealed that IGFBP4 was elevated two fold in CRF rats (P < 0.01 vs. Sham-C). However, IGFBP4 mRNA levels in liver or skeletal muscle were not different in two groups. To determine if the increase of serum IGFBP4 in CRF retarded the growth of cartilage, epiphyseal chondrocytes were isolated from CRF or control rats and cultured in the presence of control or CRF rat sera. Incubation with 10% CRF serum reduced proliferations of normal chondrocytes and L6 rat skeletal muscle cells. In contrast, 10% CRF serum did not inhibit the growth of CRF chondrocytes. Rat sera from two groups were separated into two different fractions, high (>10 kDa, containing IGFBPs) and low (<10 kDa, containing free IGF) molecular weight fractions using a gel filtration column. Both fractions obtained from CRF sera decreased the growth of control chondrocytes up to 40% compared with those from control sera. We suggest that the pathogenesis of growth failure in CRF may be involved in the increase of circulating IGFBP4 as well as the unidentified small molecular weight uremic serum factors which block the growth of chondrocytes in growth plate.

Effects of tamoxifen and octreotide LAR on the IGF-system compared with tamoxifen monotherapy

The insulin-like growth factor (IGF)-system was evaluated in 150 breast cancer patients participating in a randomised phase III trial comparing octreotide pamoate and tamoxifen with tamoxifen+placebo. Alterations in the IGF-system in the two treatment arms and individual changes with respect to outcome were compared. Serum IGF-I and -II, free IGF-I, and insulin-like growth factor binding protein 1-3 (IGFBP1-3) were measured by radioimmmunoassay (RIA)/immunoradiometric assay (IRMA) and IGFBPs by Western ligand blots (WLB) before and during treatment. Combined treatment caused a higher increase in IGFBP-1 and larger suppression of total and free IGF-I, IGF-II, and IGFBP-3 (P<0.01 for all), but less suppression of IGFBP-2 (P<0.05) compared with tamoxifen monotherapy. An increase in IGFBP-2 25% was associated with decreased progression-free survival (PFS) in the total patient population and combined treatment group. Similar response rates and time to progression in the treatment arms suggests moderate suppression of circulating IGF-I has no influence on clinical outcome.

Antioxidant vitamin and mineral supplementation and prostate cancer prevention in the SU.VI.MAX trial

Randomized trials have shown, unexpectedly, that supplementation with selenium or vitamin E is associated with a reduction of prostate cancer risk. We assess whether a supplementation with low doses of antioxidant vitamins and minerals could reduce the occurrence of prostate cancer and influence biochemical markers. The SU.VI.MAX trial comprised 5,141 men randomized to take either a placebo or a supplementation with nutritional doses of vitamin C, vitamin E, beta-carotene, selenium and zinc daily for 8 years. Biochemical markers of prostate cancer risk such as prostate-specific antigen (PSA) and insulin-like growth factors (IGFs) were measured on plasma samples collected at enrollment and at the end of follow-up from 3,616 men. Cox regression models were used to estimate the hazard ratio and related 95% confidence interval of prostate cancer associated with the supplementation and to examine whether the effect differed among predetermined susceptible subgroups. During the follow-up, 103 cases of prostate cancer were diagnosed. Overall, there was a moderate nonsignificant reduction in prostate cancer rate associated with the supplementation (hazard ratio = 0.88; 95% CI = 0.60-1.29). However, the effect differed significantly between men with normal baseline PSA (< 3 microg/L) and those with elevated PSA (p = 0.009). Among men with normal PSA, there was a marked statistically significant reduction in the rate of prostate cancer for men receiving the supplements (hazard ratio = 0.52; 95% CI = 0.29-0.92). In men with elevated PSA at baseline, the supplementation was associated with an increased incidence of prostate cancer of borderline statistical significance (hazard ratio = 1.54; 95% CI = 0.87-2.72). The supplementation had no effect on PSA or IGF levels. Our findings support the hypothesis that chemoprevention of prostate cancer can be achieved with nutritional doses of antioxidant vitamins and minerals.

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.

Longitudinal changes of insulin-like growth factors and their binding proteins throughout normal pregnancy

BACKGROUND

Insulin-like growth factors (IGFs) are anabolic proteins that are essential regulators of cell division, differentiation and growth. We describe the longitudinal changes in IGF-I, IGF-II and the binding proteins IGFBP-1, -2 and -3 before and during normal pregnancy.

METHOD

Serum samples were taken before conception and then at 12, 24 and 36 weeks of gestation in 41 healthy women with uncomplicated pregnancies. We measured IGF-I using an automated chemiluminescent method, IGF-II and IGFBP-2 using in-house radioimmunoassays (RIAs), and IGFBP-1 and IGFBP-3 using commercial enzyme-linked immunosorbent assay (ELISA) and RIA kits, respectively. Because of the potential haemodilution effects during pregnancy, albumin was also measured in all samples.

RESULTS

There was a significant fall in IGF-I during the first (36%) and second trimesters (21%) followed by an increase of 25% at 36 weeks. During pregnancy, the mean IGF-II concentrations fell by 12% at 12 weeks, 8% at 24 and 8% at 36 weeks compared with pre-conception values. When IGF-II results were adjusted for the haemodilution of pregnancy, its concentrations increased. During pregnancy, there was a rapid increase in mean IGFBP-1 levels by 17-fold (12 weeks), 24-fold (24 weeks) and 25-fold (36 weeks). IGFBP-2 concentrations fell after conception but started to increase towards term. This increase was more significant when adjusted for haemodilution. In contrast, IGFBP-3 concentrations increased significantly throughout pregnancy.

CONCLUSION

Our data on the physiological changes of IGFs and their binding proteins add further evidence of the vital roles of these hormones throughout normal pregnancy.