Home About us Contact
|
Home About us Contact | ||
|
|
||
IGF-I Concentrations (igf-i + concentration)
Selected AbstractsEndogenous sex hormones, prolactin and mammographic density in postmenopausal Norwegian womenINTERNATIONAL JOURNAL OF CANCER, Issue 11 2007Yngve Bremnes Abstract The associations between endogenous sex hormone levels and breast cancer risk in postmenopausal women are well established. Mammographic density is a strong risk factor for breast cancer, and possibly an intermediate marker. However, the results from studies on the associations between endogenous sex hormones and mammographic density are conflicting. The authors examined the associations between circulating levels of sex hormones, sex hormone binding globulin (SHBG) and prolactin and mammographic densities among postmenopausal women not currently using postmenopausal hormone therapy (HT). The authors also examined if insulin-like growth factor-I (IGF-I) levels influenced the association between estrogen and mammographic density. Altogether, 722 postmenopausal participants in the Norwegian governmental mammographic screening program had endogenous hormone concentrations measured. Mammograms were classified according to percent and absolute mammographic density using a previously validated computer-assisted method. After adjustment for age, number of children, age at menopause, body mass index and HT use, both plasma concentrations of SHBG (p -trend = 0.003) and estrone (p -trend = 0.07) were positively associated with percent mammographic density. When the analyses were stratified according to median IGF-I concentration, the weak association between estrone and mammographic density was strengthened among women with IGF-I levels below median, while the association disappeared among women with over median IGF-I levels (p for interaction = 0.02). In summary, the authors found a positive association between plasma SHBG levels and mammographic densities among 722 postmenopausal Norwegian women not currently using HT. Further, the authors found a positive but weak association between plasma estrone concentration and mammographic density, which appeared to be modified by IGF-I levels. © 2007 Wiley-Liss, Inc. [source] Insulin-like growth factor I in growing thoroughbredsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2007W. B. Staniar Summary The objective of this longitudinal study was to characterize growth and plasma insulin-like growth factor I (IGF-I) concentrations in pasture-raised thoroughbreds fed two sources of dietary energy. Mares and foals were randomly assigned to either a sugar and starch (SS) or fat and fibre (FF)-rich feed, and plasma IGF-I and growth were measured once a month from 1 to 16 months of age. These dependent variables were also compared with day length and ambient temperature. There was an association between plasma IGF-I concentration and average daily gain (ADG) (r = 0.32, p < 0.001). There were also clear seasonal patterns in both ADG and plasma IGF-I, with high values in June and May, and a low value in March. Plasma IGF-I and ADG were positively associated with day length and temperature. Plasma IGF-I was never higher (p > 0.10) in the FF group when compared with the SS group, and was higher in the SS group during a rapid growth phase in the spring of year 2 (p < 0.10). The results establish an association between ADG and IGF-I in the horse and indicate that environment and age may influence this relationship. In addition, plasma IGF-I is influenced by dietary energy source at particular times of year. This link has important implications in designing feeding management strategies that are aimed at addressing skeletal development. [source] Serum Insulin-Like Growth Factor-I Concentration in Cats with Diabetes Mellitus and AcromegalyJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2007Rebecca I.M. Berg Background: Serum insulin-like growth factor-I (IGF-I) has been used in place of serum growth hormone quantification for identifying acromegaly in diabetic cats. The utility of IGF-I as a screening test for acromegaly has not been critically evaluated. This retrospective study was performed to evaluate the usefulness of serum IGF-I concentration for identifying acromegaly. Hypothesis: Serum IGF-I is a useful screening test for acromegaly in diabetic cats. Animals: A review was made of the medical records of 74 diabetic cats that had serum IGF-I quantified. The diabetes was classified as well controlled (15 cats), poorly controlled because of problems with the insulin treatment regimen, concurrent disease, or both (40), or poorly controlled with clinical findings consistent with acromegaly (19). Methods: A review of medical records was made. Results: Serum IGF-I concentration was significantly (P < .0001) increased in acromegalic diabetic cats, compared with well-controlled and poorly controlled diabetic cats. Sensitivity and specificity for serum IGF-I concentration were 84% (95% confidence interval [CI] = 60.4,96.6%) and 92% (95% CI = 81.3,97.2%), respectively. There was no significant correlation between serum IGF-I concentration and duration of insulin treatment (r = 0.23, P= .089), insulin dosage (r = 0.14, P= .30), age (r = 0.16, P= .12), and pituitary volume (r = 0.40, P= .11), but a modest correlation was found between serum IGF-I concentration and body weight (r = 0.48, P < .0001). Conclusions and Clinical Importance: Results support the use of serum IGF-I concentration as a screening test for acromegaly in diabetic cats that have clinical findings supportive of the disease. [source] Confirmation of severe GH deficiency after final height in patients diagnosed as GH deficient during childhoodCLINICAL ENDOCRINOLOGY, Issue 4 2002Andrea F. Attanasio Summary objective Human GH treatment of patients with childhood-onset (CO) growth hormone deficiency (GHD) ceases when they reach final height; this provides an opportunity to retest GH status in all patients before determining whether GH therapy will be required in adult life. At present, the diagnostic approach to these patients is not fully standardized. This study aimed to characterize a large group of previously GH-treated CO GHD patients and establish their GH status. patients and methods The multinational study included 167 patients diagnosed as GH deficient and treated with hGH to final height during childhood. Mean age was 19·2 years and mean height standard deviation score (SDS) was ,1·08. Peak serum GH concentrations were determined in standard GH stimulation tests. IGF-I and IGFBP-3 concentrations were determined at a central laboratory and converted to SDS values by reference to a normal population. results Using only a peak GH value of less than 3 µg/l (1 mg = 3 U) in stimulation tests as the cut-off, 133 (79·6%) patients would be classed as GH deficient. Using only an IGF-I value less than ,2 SDS as the cut-off, 134 (80·2%) patients would be classed as GH deficient. However, by using both criteria there were 120 (71·9%) patients who were definitely severely GH deficient (group 1) and 20 (12·0%) who were not GH deficient (group 2), leaving 14 (8·4%) classed as GH deficient from IGF-I SDS only (group 3) and 13 (7·8%) classed as GH deficient from stimulation test only (group 4). There was no difference between the groups in height SDS or body mass index (BMI), but the GH-deficient patients tended to have been diagnosed at a younger age (group 1, 8·2 ± 3·9; group 2, 10·0 ± 4·0; P = 0·052). For patients classed as GH deficient compared with those not GH deficient, the percentage of males was lower (group 1, 64·2%; group 2, 90·0%; P = 0·022) and the percentage with multiple pituitary hormone deficiencies was higher (group 1, 81·7%; group 2, 20·0%; P < 0·001), with the other two groups being intermediate in each case. Only the group classed as GH deficient by both criteria had a mean IGFBP-3 less than ,2 SDS and both IGF-I SDS and IGFBP-3 SDS increased steadily across the four groups. conclusions A high percentage (71·9%) of these childhood-onset GH-deficient patients were still GH deficient in adult life and are likely to require further hGH treatment. While 12·0% could be classed as definitely no longer GH deficient, there are some patients who are intermediate (16·2%) and may be classed as GH deficient by one criterion but not the other. When GH stimulation test results and IGF-I concentration are discordant, the IGFBP-3 level does not establish diagnosis and the hGH treatment requirement of such patients remains a dilemma. [source] Insulin-like growth factors in patients with liver cystsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2004Olgica Nedi Abstract Insulin-like growth factors (IGFs) play an important role in cell growth and differentiation, and the liver is the main source of IGFs and IGF-binding proteins (IGFBPs) that appear in the circulation. The effect of liver cysts on the circulating IGF system was studied in this work. Serum concentrations of IGF-I and -II were measured by radioimmunoassay, IGFBP patterns were characterised by ligand-affinity and immunoblotting, and a lectin-binding assay was used to investigate the glyco component of IGFBP-3 complexes. IGF-I and -II concentrations in patients with cysts were significantly lower compared to those in healthy individuals (P<0.0001 and P<0.01, respectively), and the decrease was related to age but not sex. The overall mean concentrations of IGF-I and -II were not significantly different whether the cysts were caused by Echinococcus granulosus, cross-reactive pathologies, or some other factor. IGFBP profiles correlated with the amount of IGF present: patients with lower IGF-I concentrations expressed decreased IGFBP-3 and elevated IGFBP-2 levels. Increased IGFBP-3 proteolytic activity in the patients' blood was not detected by immunoblotting. In the lectin-binding assay, IGFBP-3 complexes in the circulation of patients demonstrated reactivity similar to that in healthy persons, suggesting that the overall structure of the saccharide moieties of the IGFBP-3 complexes was not significantly altered due to liver cyst formation. J. Clin. Lab. Anal. 18:299,304, 2004. © 2004 Wiley-Liss, Inc. [source] The Inhibition of Inducible Nitric Oxide Synthase Reverts Arthritic-Induced Decrease in Pituitary Growth Hormone mRNA But Not in Liver Insulin-Like Growth Factor I mRNA ExpressionJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2003I. Ibáńez De Cáceres Abstract Experimental arthritis induced by Freund-adjuvant administration is a model of chronic inflammation and rheumatoid arthritis associated with a decrease in pituitary growth hormone (GH) and hepatic insulin-like growth factor I (IGF-I) gene expression. Excessive nitric oxide (NO) synthesis by inducible NO synthase (iNOS) has been implicated in the pathogenesis of inflammatory illness. Moreover, NO participates in the regulation of GH secretion at both the hypothalamus and the pituitary. We have examined the role of iNOS activation in producing the changes in the GH-IGF-I axis in arthritic rats. Adult male Wistar rats received aminoguanidine or vehicle from day 20, after adjuvant or vehicle injection, until day 28. Two hours and 30 min after the last aminoguanidine injection, all rats were killed by decapitation. Arthritis increased hypothalamic expression of somatostatin mRNA while it decreased pituitary GH mRNA expression, and both effects were prevented by aminoguanidine administration. In arthritic rats, the parallel decrease in serum IGF-I, and in hepatic IGF-I content and mRNA expression, correlates with the decrease in circulating GH concentrations. Aminoguanidine administration to arthritic rats did not modify either serum GH or serum IGF-I concentrations, or hepatic IGF-I mRNA expression. However, aminoguanidine administration to control rats resulted in a decrease in serum GH concentrations and in a decrease in both hepatic IGF-I mRNA expression and serum IGF-I concentrations. These data suggest that NO mediates the arthritis-induced decrease in GH mRNA expression by acting at a hypothalamic level, but it is not involved in the decrease in hepatic IGF-I mRNA expression. [source] Profound changes in the GH,IGF-I system in adolescent girls with IDDM: can IGFBP1 be used to reflect overall glucose regulation?PEDIATRIC DIABETES, Issue 3 2000MU Halldin Disturbances in the relations between insulin, growth hormone (GH) and insulin-like growth factor I (IGF-I) may be a major cause behind deteriorated metabolic control in adolescent girls with type I diabetes. These patients have increased GH secretion and low IGF-I concentrations. The aim of this study was to identify possible endocrine mechanisms behind good and poor glycaemic control in such girls, focusing on the insulin,GH,IGF-I axis. Ten girls with well-controlled insulin-dependent diabetes mellitus (IDDM), hemoglobin A1c (HbA1c) 6.5±0.4% (normal range 3.9,5.2%) and nine healthy controls were investigated and compared with 11 girls with poor glucose regulation, HbA1c 10.9±0.4%, and their corresponding controls. Serum profiles of glucose, insulin, GH and IGF-binding protein 1 (IGFBP1) were analysed in addition to IGF-I and HbA1c. Two interesting observations were made. GH concentrations were equally elevated in the two diabetic groups regardless of metabolic control (mean 24 h GH , girls with poorly controlled diabetes 10.0±1.0 mU/L vs 9.8±1.7 , girls with well-controlled diabetes; p=ns). Likewise, the IGF-I concentrations were reduced to the same extent (233±19 vs 242±23 ,g/L; p=0.75). Secondly, despite similar insulin concentrations (mean 24 h insulin , girls with poorly controlled diabetes 22.9±2.6 and girls with well-controlled diabetes 27.3±2.9 mU/L, respectively; p=0.26), there was a marked difference in IGFBP1 concentrations between the two groups with IDDM (mean IGFBP1 , girls with poorly controlled diabetes 70.5±9.1 ,g/L vs girls with well-controlled diabetes 28.6±3.3; p<0.001). Despite equally elevated GH concentrations that may induce insulin resistance, the markedly lower concentrations of IGFBP1 in the well-controlled group indicate a higher hepatic insulin sensitivity in these girls compared with those with a poor control. Furthermore, in spite of similar total IGF-I concentrations, the lower IGFBP1 concentrations may result in higher IGF-I bioactivity in the well-controlled group. This may be reflected in better growth of the well-controlled group whose height of 168.7±0.9 vs 163.6±1.2 cm was significantly different (p<0.004). IGFBP1 may be a marker of overall insulinization in adolescents with type 1 diabetes, independent of the absolute insulin dose used for therapy. [source] One-year follow-up of patients with acromegaly treated with fixed or titrated doses of lanreotide Autogel®CLINICAL ENDOCRINOLOGY, Issue 6 2004Ph. Caron Summary objective, Somatostatin analogue treatment is first-line medical therapy for acromegaly. This study compared the efficacy and tolerability of titrated doses of the long-acting somatostatin analogue preparation lanreotide Autogel® with fixed doses and with lanreotide prolonged release (PR) 30 mg microparticles. patients, Patients entering the initial study had received a diagnosis of active acromegaly within the previous 5 years. design, This open, comparative, multicentre study was a 1-year extension of a previous trial during which patients with acromegaly had switched from lanreotide PR 30 mg microparticles injected intramuscularly every 7, 10 or 14 days, for at least 3 months, to one of three fixed doses of lanreotide Autogel® (120, 90, or 60 mg every 28 days, respectively). In this extension study, patients continued to receive 60, 90, or 120 mg of lanreotide Autogel® by deep subcutaneous injection every 28 days for 1 year. Doses could be titrated at entry or after four or eight injections, according to the GH/IGF-I response (dose increased if GH > 2·5 µg/l, or decreased if GH < 1 µg/l with normal IGF-I). measurements, Mean ± SEM GH and IGF-I concentrations were analysed and gallbladder echography performed at weeks 0, 16, 32, and 48. Acromegaly symptoms were recorded monthly and tolerance and side-effects were monitored throughout the study. results, In total, 130 patients entered this extension phase. After 1 year of treatment with titrated doses of lanreotide Autogel®, mean GH (2·4 ± 0·2 µg/l) and IGF-I (287 ± 12 µg/l) concentrations were significantly lower than with lanreotide microparticles (GH, 2·8 ± 0·2 µg/l, P < 0·001; IGF-I, 332 ± 15 µg/l, P < 0·01) or with fixed-dose lanreotide Autogel® (GH, 3·0 ± 0·2 µg/l, P < 0·001; IGF-I, 310 ± 14 µg/l, P = 0·02). GH hypersecretion was reduced to , 2·5 µg/l in 68% of patients with titrated-dose lanreotide Autogel® compared with 49% with microparticles (P < 0·001) and 56% with fixed-dose lanreotide Autogel® (P , 0·005). In the 65 patients who did not require any dose titration, there was no substantial change in serum lanreotide concentration, GH or IGF-I levels over the 12-month study duration. Acromegaly was effectively controlled (GH , 2·5 µg/l and normalized IGF-I) in significantly more patients (43%) compared with microparticles (32%; P < 0·05). There was a trend for improved control of acromegalic symptoms with dose titration, whereas the incidence of gastrointestinal symptoms and local tolerance was similar with lanreotide Autogel® and lanreotide microparticles. Gallbladder echographies showed new lithiasis in 8% of lanreotide Autogel® patients. conclusion, Dose titration of lanreotide Autogel® improved GH and IGF-I control in patients with acromegaly beyond that achieved using fixed doses of lanreotide Autogel® or lanreotide microparticles. Titrated long-term lanreotide Autogel® treatment is well tolerated. [source] | ||||||||||