Urinary growth hormone (GH), insulin-like growth factor I (IGF-I), and IGF-binding protein-3 measurements in the diagnosis of adult GH deficiency

The diagnosis of GH deficiency (GHD) in the elderly is based at present on the peak GH concentration during a stimulation test. We have now evaluated the performance of urinary GH (uGH), urinary insulin-like growth factor I (uIGF-I), and urinary IGF-binding protein-3 (uIGFBP-3) in the diagnosis of GHD in this group. Twenty GHD elderly patients with a history of pituitary disease and a peak GH response to arginine stimulation of less than 3 ng/mL (15 men and 5 women; age, 61.1-83.4 yr) and 19 controls (12 men and 7 women; age, 60.8-87.5 yr) were studied. GH secretion was assessed by 24-h profile and expressed as the area under the curve (AUCGH). Serum (s) IGF-I and sIGFBP-3 were measured in a single morning, fasted sample. Urinary GH, uIGF-I, and uIGFBP-3 were measured in a 24-h urine sample collected over the same interval as the GH profile, and results were expressed as total amount excreted in 24 h (tuGH24, nanograms; tuIGF-I24, nanograms; tuIGFBP-3(24), micrograms). Data are presented as the mean +/- SD, except for AUCGH, tuGH24, and tuIGFBP-3(24), which are presented as the geometric mean (-1, +1 tolerance factor). AUCGH, sIGF-I, and sIGFBP-3 were significantly lower in GHD subjects than in controls. Total uGH24 was lower in GHD subjects, but tuIGF-I24 and tuIGFBP-3(24) excretion were not different in the two groups. AUCGH provided the best separation between GHD and control subjects, whereas there was substantial overlap for sIGF-I, sIGFBP-3, and tuGH24. In both groups sIGF-I was correlated to sIGFBP-3 (GHD, r = 0.75; controls, r = 0.65; both P < 0.01), whereas tuIGF-I24 was not correlated to tuIGFBP-3(24) in either group. Moreover, tuIGF-I24 and tuIGFBP-3(24) were not related to their respective serum concentrations in either group. Total uGH24 was correlated with AUCGH only in controls (r = 0.54; P < 0.05). These data demonstrate that urinary GH and urinary and serum IGF-I and IGFBP-3 are not suitable diagnostic markers for GHD in elderly subjects.     

Developmental changes in serum levels of free and total insulin-like growth factor I (IGF-I), IGF-binding protein-1 and -3, and the acid-labile subunit in rats

We have recently described a competitive binding assay for rat insulin-like growth factor-binding protein-3 (IGFBP-3) based on the ability of IGFBP-3 to form a ternary complex with the acid-labile subunit (ALS) in the presence of IGF-I. Using this assay we studied groups of male (n = 6) and female rats (n = 6) at 20, 30, 40, 50, 60, 80, and 130 days of age. Nonfasting serum levels of IGFBP-3 were compared with those of total (extractable) IGF-I (tIGF-I) and ALS as well as IGFBP-3 determined by ligand blotting. Additionally, we studied the relationship between ultrafiltered free IGF-I (fIGF-I) and immunoassayable IGFBP-1. IGFBP-3 was dependent on age only (P < 0.0001), but tended to be higher in males than in females (P = 0.06); between 20-130 days levels increased from 6.5 +/- 1.7 to 73.6 +/- 7.2 nmol/liter in males and from 5.4 +/- 1.6 to 51.3 +/- 8.0 nmol/liter in females. IGFBP-3 correlated positively with tIGF-I (r = 0.90; P < 0.0001), ALS (r = 0.92; P < 0.0001), and IGFBP-3, as determined by ligand blotting (r = 0.88; P < 0.0001). The molar ratio of IGFBP-3 to tIGF-I increased from 0.23 +/- 0.04 to 0.76 +/- 0.04 (P < 0.0001) without any sex dependence. An age- and sex-dependent decrease in IGFBP-1 was observed (P < 0.0001), from 10.9 +/- 2.5 to 1.2 +/- 0.2 nmol/liter in females and from 8.9 +/- 0.7 to 0.2 +/- 0.04 nmol/liter in males. Free IGF-I (fIGF-I) increased with age (from 0.7 +/- 0.2 to 7.1 +/- 0.5 nmol/liter; P < 0.0001), and levels were inversely correlated with IGFBP-1 (r = -0.80; P < 0.0001). In young rats, IGFBP-1 circulated in a 10-fold molar excess over the level of fIGF-I, whereas in older rats, fIGF-I exceeded IGFBP-1 by an average of 9-fold in females and by up to almost 60-fold in males. We conclude that in rats 1) IGFBP-3 and fIGF-I are strongly age dependent; 2) IGFBP-3 correlates positively with ALS and tIGF-I; and 3) fIGF-I and IGFBP-1 are inversely correlated. This is in accordance with clinical findings. However, in humans the adult level of fIGF-I rarely exceeds 0.3 nmol/liter, and IGFBP-1 usually circulates in excess of fIGF-I. Thus, our results also imply species differences in the IGF systems of humans and rats.     

Osteogenic protein-1 regulates insulin-like growth factor-I (IGF-I), IGF-II, and IGF-binding protein-5 (IGFBP-5) gene expression in fetal rat calvaria cells by different mechanisms

Agrobacterium tumefaciens beta-glucosidase, Cbg1 was extensively characterised and found to be a retaining aryl-glucosidase and an aryl-xylosidase. Cbg1s specificity for p-nitrophenyl beta-d-xylopyranoside was 73% that for p-nitrophenyl beta-d-glucopyranoside when measured by the ratio kcat/Km. The enzyme also hydrolysed p-nitrophenyl beta-d-fucopyranoside, and p-nitrophenyl beta-d-galactopyranoside with moderate efficiency. The enzyme released only terminal glucose from p-nitrophenyl beta-cellobioside and had a 20 000-fold preference for its natural substrate coniferin over cellobiose as indicated by the ratio kcat/Km. The enzyme was activated in the presence of 20 mM 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol. In the case of butanol this activation was investigated and shown to be due to transglycosylation activity with over 80% of p-nitrophenyl beta-d-glucopyranoside being converted to 1-butyl beta-d-glucopyranoside in the presence of Cbg1 and 100 mM 1-butanol.     

Alcohol withdrawal-induced change in lipoprotein(a): association with the growth hormone/insulin-like growth factor-I (IGF-I)/IGF-binding protein-1 (IGFBP-1) axis

Lipoprotein(a) [Lp(a)] is an important risk factor for cardiovascular disease. Alcohol is one of the few nongenetic factors that lower Lp(a) levels, but the metabolic mechanisms of this action are unknown. Alcohol inhibits the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. Alcohol might also affect IGF-binding protein-1 (IGFBP-1), which is an acute inhibitor of IGF-I. We studied how alcohol withdrawal affects Lp(a) levels and the GH/IGF-I/IGFBP-1 axis. Male alcohol abusers (n=27; 20 to 64 years old) were monitored immediately after alcohol withdrawal for 4 days. Twenty-six healthy men, mainly moderate drinkers, served as control subjects. Fasting blood samples were drawn to determine Lp(a), IGF-I, and IGFBP-1 (by ELISA, RIA, and immunoenzymometric assay, respectively). Nocturnal (12 hours) urine collection was performed in 9 alcoholics and 11 control subjects for GH analyses (RIA). The groups were similar in age and body mass index. Lp(a), GH, and IGF-I tended to be lower and IGFBP-1 higher in the alcoholics immediately after alcohol withdrawal than in the control subjects. During the 4-day observation in alcoholics, Lp(a) levels increased by 64% and IGF-I levels by 41%, whereas IGFBP-1 levels decreased by 59% (P<.001 after ANOVA for all comparisons). Urinary GH levels tended to decline. The increase in Lp(a) correlated inversely with the changes in IGFBP-1 (r= -.63, P<.001, n=27) and GH (r=-.70, P<.05, n=9), but not with IGF-I. In multiple regression analysis, the main predictors for the increase in Lp(a) were IGFBP-1 and urinary GH. In conclusion, alcohol withdrawal induces interrelated and potentially atherogenic changes in Lp(a) and IGFBP-1 levels.     

Filter paper blood spot assay of human insulin-like growth factor I (IGF-I) and IGF-binding protein-3 and preliminary application in the evaluation of growth hormone status

To facilitate broader applications of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) analysis, we developed procedures for their measurements in extracts of whole blood dried on filter paper. A single 8-mm diameter filter paper disc containing about 13 microL blood was used. IGFBP-3 was efficiently extracted in a buffer within 1 h of incubation. IGF-I extraction involved incubation in buffer followed by acidification and neutralization steps. Blood spot assays showed intra- and interassay coefficients of variation (including interspot variations) of 5.4-16.7% for IGF-I and 6.6-11.7% for IGFBP-3; recoveries were 97 +/- 7.1% and 101 +/- 8.7%, respectively. Recoveries of IGF-I and IGFBP-3 in response to 4- to 8-fold variations in extraction buffer volume were 97 +/- 8.2% and 107 +/- 6.1%, respectively. Dried blood spot IGF-I and IGFBP-3 showed greater than 1-month stability at -20 C, 4 C, and room temperature and retained more than 65% of the immunoreactivity after approximately 1 month at 37 C. Both IGF-I and IGFBP-3 were contained within the plasma fraction of whole blood, and variations (mean +/- SD) in IGF-I (204 +/- 29 micrograms/L) and IGFBP-3 (4.4 +/- 0.48 mg/L) measured in extracts of dried blood spot with adjusted hematocrit of 0.2-0.62 were acceptable. IGF-I and IGFBP-3 in paired plasma and dried blood spot extracts of random samples (n = 46) showed excellent correlation (r > 0.94) with slopes of near unity. Compared to conventional methods, the filter paper procedures were equally effective in distinguishing IGF-I and IGFBP-3 levels in untreated GH receptor-deficient (n = 11) and age-matched normal controls (n = 16). We conclude that blood collected on filter paper is ideal for IGF-I and IGFBP-3 analysis and may find applications in pediatric and large scale infant screening programs.     

Structure of the IGF-binding domain of the insulin-like growth factor-binding protein-5 (IGFBP-5): implications for IGF and IGF-I receptor interactions

Binding proteins for insulin-like growth factors (IGFs) IGF-I and IGF-II, known as IGFBPs, control the distribution, function and activity of IGFs in various cell tissues and body fluids. Insulin-like growth factor-binding protein-5 (IGFBP-5) is known to modulate the stimulatory effects of IGFs and is the major IGF-binding protein in bone tissue. We have expressed two N-terminal fragments of IGFBP-5 in Escherichia coli; the first encodes the N-terminal domain of the protein (residues 1-104) and the second, mini-IGFBP-5, comprises residues Ala40 to Ile92. We show that the entire IGFBP-5 protein contains only one high-affinity binding site for IGFs, located in mini-IGFBP-5. The solution structure of mini-IGFBP-5, determined by nuclear magnetic resonance spectroscopy, discloses a rigid, globular structure that consists of a centrally located three-stranded anti-parallel beta-sheet. Its scaffold is stabilized further by two inside packed disulfide bridges. The binding to IGFs, which is in the nanomolar range, involves conserved Leu and Val residues localized in a hydrophobic patch on the surface of the IGFBP-5 protein. Remarkably, the IGF-I receptor binding assays of IGFBP-5 showed that IGFBP-5 inhibits the binding of IGFs to the IGF-I receptor, resulting in reduction of receptor stimulation and autophosphorylation. Compared with the full-length IGFBP-5, the smaller N-terminal fragments were less efficient inhibitors of the IGF-I receptor binding of IGFs.     

Use of insulin-like growth factor I (IGF-I) and IGF-binding protein measurements to monitor feeding of premature infants

To determine whether peptides of the insulin-like growth factor (IGF) system might be useful indicators of nutritional adequacy in premature infants, we studied 50 premature (25-34 weeks gestation) infants prospectively to define the relationship between nutrient intake and serum concentrations of IGF-I, IGF-binding protein-2 (IGFBP-2), and IGFBP-3. Each infant was monitored for at least 2 weeks. Nutrient intake was quantified from daily logs; weight was determined daily, and measurements of IGF-I, IGFBP-2, and IGFBP-3 in serum were made twice weekly. Serum IGF-I correlated strongly with length of gestation, increasing 4.03 +/- 0.95 ng/mL for each additional week of gestation (P < 0.0001) and 0.36 +/- 0.07 ng/mL day each day since birth (P < 0.0001). A higher intake of calories increased IGF-I by 0.07 +/- 0.01 ng/mL for each calorie per kg ingested over the previous 3 days (P < 0.0001). IGF-I increased quadratically as protein intake increased. For each change of 1% in calories as protein squared, IGF-I increased 0.36 +/- 0.11 ng/mL (P < 0.0001). Serum IGFBP-3 concentrations also correlated with length of gestation, increasing 25.06 +/- 11.83 micrograms/L.wk (P = 0.035) and 4.14 +/- 1.33 micrograms/.day since birth (P = 0.003). Unlike IGF-I, variation in the amount of protein supplied did not change IGFBP-3. As calorie intake increased, IGFBP-3 increased by 0.54 +/- 0.17 microgram/L for each calorie per kg consumed over the previous 3 days (P = 0.0015). In contrast to IGF-I and IGFBP-3, IGFBP-2 declined as the length of gestation increased (56.12 +/- 16.92 ng/mL.week; P = 0.001) and with each additional day of life (7.57 +/- 2.44 ng/mL.day; P = 0.003). Dietary protein, the predominant regulator of IGFBP-2, caused a decrease of 33.22 +/- 9.00 ng/mL with each percent increase in dietary calories as protein (P < 0.0003). Calorie intake had less effect on IGFBP-2 than protein intake. These results indicate that each of the three peptides studied is regulated in premature infants by nutritional intake, and that their regulatory patterns are qualitatively similar to those observed in older individuals. Measurements of these peptides in premature infants may be useful indicators of nutritional status and adequacy of nutrient intake.     

Use of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in the diagnosis of acromegaly and growth hormone deficiency in adults

The goal of our study was to compare the clinical usefulness of plasma insulin-like growth factor-I (IGF-I) (with and without binding protein extraction) and IGF binding protein-3 (IGFBP-3) measurements in the diagnosis of growth hormone (GH) disorders in adults. IGF-I and IGFBP-3 concentrations were measured in 25 acromegalic and 25 GH-deficient adult (GHDA) subjects (20-76 years) by comparison to a control population (n = 81) after age and sex stratification. In untreated acromegaly, IGF-I and IGFBP-3 were clearly increased (10 times the mean of controls for unextracted IGF-I, 4 times for extracted IGF-I and 2 times for IGFBP-3). Using the mean + 2SD of the control population as the cut-off point, the sensitivity of IGF-I for the diagnosis of acromegaly was higher than that of IGFBP-3 (unextracted IGF-I: 96% and extracted IGF-I: 100% vs IGFBP-3: 76%). In GHDAs, IGF-I and IGFBP-3 were decreased (34% of the mean of controls for unextracted IGF-I, 37% for extracted IGF-I and 70% for IGFBP-3). Using the mean - 2SD of the control population as the cut-off point, the sensitivity of IGF-I measurement for the diagnosis of GHDA was relatively low, but better for unextracted (68%) than for extracted IGF-I (52%). The sensitivity of IGFBP-3 was much lower (36%), thus invalidating this parameter for the diagnosis of GHDA. Our observations demonstrate that IGF-I measurement is a more powerful tool than IGFBP-3 measurement for the diagnosis of GH disorders in adults. Both IGF-I and IGFBP-3 are very useful for the diagnosis of acromegaly, but they are less reliable for diagnosing GHDA, as normal IGF-I or IGFBP-3 values do not rule out GH deficiency.     

Regulation of experimental autoimmune encephalomyelitis with insulin-like growth factor (IGF-1) and IGF-1/IGF-binding protein-3 complex (IGF-1/IGFBP3)

Insulin-like growth factor (IGF)-1 is a cytokine that promotes oligodendrocyte development and myelin production. This study investigated whether treatment of chronic, relapsing murine experimental autoimmune encephalomyelitis (EAE) with IGF-1 or IGF-1 associated with its binding protein, IGFBP3, altered the course of disease. Administration of IGF-1/IGFBP3 (1-100 mg/kg per day) delayed the onset of disease in a dose-dependent manner and histologic examination showed a delay in inflammatory cells entering the central nervous system. However, once signs of EAE developed, disease was enhanced in the mice that had been given the highest dose of IGF-1/IGFBP3. Treatment with IGF-1/IGFBP3 after the onset of signs resulted in a severe relapse. Administration of free IGF-1 (10 mg/kg per day) provided mild protection when given before disease onset, but did not significantly alter the course of disease if given after disease onset. Possible mechanisms that could explain the altered disease in IGF-1/IGFBP3-treated mice included (a) IGF-1/IGFBP3 administration delayed the onset of EAE by downregulating ICAM-1 gene expression in the central nervous system, and (b) IGF-1/IGFBP3 treatment of EAE resulted in more severe disease due to enhanced expansion of encephalitogenic T cells. Although IGF-1 may enhance remyelination, these results indicate that administration of IGF-1 associated with IGFBP3 may also accentuate autoimmune demyelinating disease.     

Randomised placebo-controlled trial of human recombinant insulin-like growth factor I plus intensive insulin therapy in adolescents with insulin-dependent diabetes mellitus

BACKGROUND: Good glycaemic control in insulin-dependent diabetes mellitus (IDDM) to prevent complications may be difficult to achieve during adolescence, because abnormalities in production of growth hormone or insulin-like growth-factor-I (IGF-I) can lead to lower insulin sensitivity. Recombinant human IGF-I (rhIGF-I) given as an adjunct to insulin therapy in IDDM, might improve glycaemic control in adolescents; we investigated the effects of the addition of IGF-I in a randomised, double-blind, placebo-controlled trial. METHODS: 53 patients with IDDM (26 male, 27 female) with a median age of 16.1 years (range 10.8-20.6) and diabetes of more than 2 years' duration were randomly assigned subcutaneous rhIGF-I (20 or 40 microg/kg daily [n=18, n=18, respectively]) or placebo (n=17), both in addition to multiple-injection insulin therapy for 24 weeks. The primary endpoint, glycated haemoglobin (HbA1c) and routine biochemistry were measured every 4 weeks. Retinal photographs and glomerular-filtration rates were assessed at base line and at the end of the study. Data were analysed by intention to treat. FINDINGS: With a dose of 40 microg/kg rhIGF-I daily, we found significant reductions in HbA1c compared with placebo (p=0.03), without changes in body-mass index, rate of hypoglycaemia, insulin dose, or circulating concentrations of IGF-binding proteins 1 and 3. The greatest median change in HbA1c of -0.6% (range -2.8 to -1.5%) was seen with rhIGF-I 40 microg/kg at week 12, but was not sustained at week 24. The greatest reductions in HbA1c at week 24 were seen among patients with the greatest changes in IGF-I concentrations (r=-0442, p=0.002). Retinal photographs, renal function (glomerular filtration rate and urinary albumin excretion), and routine biochemistry showed no adverse events. INTERPRETATION: Our data confirm that rhIGF-I as an adjunct to insulin therapy can improve HbA1c values in adolescents with IDDM without overt toxic effects, but they raise questions about whether these effects can be sustained in cases of poor compliance or reduced bioefficacy.     

Long-term effects of insulin-like growth factor (IGF)-I on serum IGF-I, IGF-binding protein-3 and acid labile subunit in Laron syndrome patients with normal growth hormone binding protein

A minority of patients with Laron syndrome have normal serum GH binding protein (GHBP), indicating that the defect is elsewhere than in the extracellular domain of the GH receptor. We have evaluated the effect of long-term IGF-I treatment on serum IGF-binding protein (IGFBP)-3 and the acid-labile subunit (ALS) in three sibling with Laron syndrome caused by a GH post-receptor defect and with normal GHBP. The children (a boy aged 3 years, a girl aged 4 years and a boy aged 10 years) were treated by daily s.c. injection of IGF-I in a dose of 150 micrograms/kg. IGFBP-3 was measured by RIA and Western ligand blotting, ALS by RIA. Based values of IGFBP-3 and ALS were low. During IGF-I treatment, the IGFBP-3 concentrations in the girl gradually increased, whereas in the boys there was a 60% decrease during the first week, followed by gradual increase towards baseline. The ALS concentrations followed a similar pattern. We conclude that IGF-I treatment induces and initial suppression and then an increase in the IGFBP-3 and ALS concentrations, confirming data from animal experiments that IGFBP-3 synthesis is not solely under GH control. The differences in responsiveness between the female and male siblings may reflect genetic differences, or lower circulating concentrations of IGF-I in the boys compared with the girl.     

Serum free and total insulin-like growth factor-I, insulin-like growth factor binding protein-1 and insulin-like growth factor binding protein-3 Levels in healthy elderly individuals. Relation to self-reported quality of health and disability

Numerous controlled trials have demonstrated the efficacy of specific immunotherapy, although its mechanism is not completely understood. Few studies have addressed the effects of immunotherapy on the release of mediators. We measured in vitro sulphidoleukotriene (sLT) and histamine release after specific stimulus (Dermatophagoides pteronyssinus or Lollium perenne) in a group of patients under immunotherapy (n = 35) and compared the results with those obtained in a group of allergic patients without immunotherapy (n = 57). SLT quantification was carried out by cellular stimulation allergen test (CAST)-ELISA and we measured the amount of histamine release using a fluorometric method. We found a significant (p < 0.05) reduction of allergen-specific mediator release on the group of patients under immunotherapy treatment. When we studied the group of patients sensitive to D. pteronyssinus we also observed a significant reduction in sLT release after the in vitro stimulus with anti-IgE. In vitro sLT production could be a good marker for follow-up immunotherapy. This study provides more evidence to support the immunological and cellular changes induced by immunotherapy.     

Developmental pattern of fetal growth hormone, insulin-like growth factor I, growth hormone binding protein and insulin-like growth factor binding protein-3

AIMS: To evaluate the developmental pattern of fetal growth hormone (GH), insulin-like growth factor I (IGF-I), GH binding protein (GHBP) and IGF binding protein-3 (IGF-3); to determine the implications for fetal growth. METHODS: Serum GH, IGF-I, GHBP and IGFBP-3 were measured in 53 fetuses, 41 aged 20-26 weeks (group A) and 12 aged 31-38 weeks (group B). Fetal blood samples were obtained by direct puncture of the umbilical vein in utero. Fetal blood samples were taken to rule out beta thalassaemia, chromosome alterations, mother to fetus transmissible infections, and for maternal rhesus factor. GHBP was determined by gel filtration chromatography of serum incubated overnight with 125I-GH. GH, IGF-I and IGFBP-3 were determined by radioimmunoassay. RESULTS: Fetal serum GH concentrations in group A (median 29 micrograms/l, range 11-92) were significantly higher (P < 0.01) than those of group B (median 16.7 micrograms/l, range 4.5-29). IGF-I in group A (median 20 micrograms/l, range 4.1-53.3) was significantly lower (P < 0.01) than in group B (median 75.2 micrograms/l, range 27.8-122.3). Similarly, IGFBP-3 concentrations in group A (median 950 micrograms/l, range 580-1260) were significantly lower than those of group B (median 1920 micrograms/l, range 1070-1770). There was no significant difference between GHBP values in group A (median 8.6%, range 6.6-12.6) and group B (median 8.3%, range 6-14.3). Gestational age correlated positively with IGF-I concentrations (P < 0.0001) and IGFBP-3 (P < 0.0001) and negatively with GH (P < 0.0001). GHBP values did not correlate with gestational age. Multiple regression analysis showed a negative correlation between GH:IGF-I ratio and fetal growth indices CONCLUSIONS: The simultaneous evaluation of fetal GH, IGF-I, IGFBP-3 and GHBP suggests that the GH-IGF-I axis might already be functional in utero. The progressive improvement in the efficiency of this axis in the last part of gestation does not seem to be due to an increase in GH receptors.     

Improvement of lipid profile in type 2 (non-insulin-dependent) diabetes mellitus by insulin-like growth factor I

Type 2 (non-insulin-dependent) diabetes mellitus is associated with increased glucose, insulin, total and VLDL-triglyceride, and often total and LDL-cholesterol levels which promote vascular disease. Recombinant human insulin-like growth factor-I which mimics many effects of insulin, decreased insulin, total and VLDL-triglyceride, and total and LDL-cholesterol levels in healthy man as well as glucose and insulin levels in Type 2 diabetic patients. We, therefore, investigated total and fractionated triglyceride and cholesterol levels, lipoprotein(a), non-esterified fatty acid, and apolipoprotein levels in eight Type 2 diabetic patients during five control, five treatment, and three wash-out days. They received a constant diet throughout and daily 2 x 120 micrograms insulin-like growth factor-I/kg s.c. during the treatment period. Fasting total and VLDL-triglyceride, total and LDL-cholesterol control levels were (mean +/- SD) 3.1 +/- 2.6, 1.3 +/- 1.0, 6.3 +/- 1.3, and 4.5 +/- 1.1 mmol/l and decreased to 1.6 +/- 0.8, 0.6 +/- 0.4, 5.0 +/- 1.0, and 3.5 +/- 1.1 mmol/l, respectively, on the last treatment day (p < 0.01). During therapy, fasting lipoprotein(a) levels and the postprandial area under the triglyceride curve decreased by 48 +/- 22 and 32 +/- 18% of control (p < 0.01), respectively. In conclusion, insulin-like growth factor-I lowered lipid levels in Type 2 diabetic patients directly or indirectly or both because of decreased glucose and insulin levels. Long-term trials would be of interest with respect to the cardiovascular risk in Type 2 diabetes and patients with hyperlipidaemia.     

Effects of treatment with megestrol acetate, aminoglutethimide, or formestane on insulin-like growth factor (IGF) I and II, IGF-binding proteins (IGFBPs), and IGFBP-3 protease status in patients with advanced breast cancer

The effects of treatment with the aromatase inhibitors aminoglutethimide (AG) and formestane or the synthetic progestin megestrol acetate (MA) on plasma levels of insulin-like growth factor I (IGF-1), IGF-II, IGF-binding proteins (IGFBPs), and IGFBP-3 protease status were investigated in 39 patients suffering from advanced breast cancer. Treatment with AG and MA elevated plasma levels of IGF-I by mean values of 27% (n = 15; P < 0.025) and 81% (n = 7; P < 0.025), respectively, whereas treatment with formestane had no effect (n = 13). Treatment with AG increased plasma levels of IGFBP-2, as evaluated by Western blotting (P < 0.01). MA caused a significant reduction in IGFBP-3 protease activity (mean reduction, 69%; P < 0.05). These alterations in plasma IGF-I and IGFBP-3 protease activity were reversed 4 weeks after terminating MA therapy (n = 8; P < 0.025). Taken together, 13 of 15 patients had reduced IGFBP-3 protease activity during treatment with MA compared to the control situation (P < 0.0025). Total levels of IGFBP-3 as measured by RIA were moderately elevated by treatment with MA (mean increase, 19%; P < 0.05), and Western immunoblotting revealed an increase in the amount of intact IGFBP-3 and reduced amounts of IGFBP-3 in the modified form. None of the treatment modalities had any influence on plasma levels of IGF-II. The increase in the plasma IGF-I concentration seen during treatment with MA may be secondary to an increased level of intact IGFBP-3. This could reflect an alteration in IGF availability that contributes to the antitumor effect of MA.     

Biosensor measurement of the binding of insulin-like growth factors I and II and their analogues to the insulin-like growth factor-binding protein-3

Most insulin-like growth factor (IGF) molecules in the circulation are found in a 150-kDa complex containing IGF-binding protein-3 (IGFBP-3) and an acid-labile subunit, which does not itself bind IGF. Affinities (Kd values) between 0.03 and 0.5 nM have been reported for IGF-I/IGFBP-3 binding, but no kinetic data are available. In this study we measured the high affinity binding of unlabeled IGFs and IGF analogues to recombinant unglycosylated IGFBP-3, using a BIAcoretrade mark instrument (Pharmacia Biosensor AB). IGF-I binding showed fast association and slow non-first-order dissociation kinetics, and an equilibrium Kd of 0.23 nM. IGF-II had similar kinetics with slightly higher affinity. Analogues with mutations in the first 3 amino acids of the B-region (des(1-3) IGF-I and long IGF-I) showed 25 and 50 times lower affinity than IGF-I. Replacement of residues 28-37 by Gly-Gly-Gly-Gly or deletion of residues 29-41 in the C-region had little effect on the kinetic parameters, contrasting with the markedly impaired binding of these analogues to the IGF-I receptor. Swapping of the disulfide bridges in IGF-I and the C-region mutants decreased the affinity dramatically for IGFBP-3, primarily by decreasing the association rate. Insulin had approximately 1000 times lower affinity than IGF-I.     

Porcine insulin-like growth factor (IGF)-binding protein-3 elicits bi-phasic effects on IGF-I stimulated DNA synthesis in neonatal porcine skin fibroblasts

The present study was undertaken to investigate the effects of porcine IGFBP-3 on IGF-I stimulated DNA synthesis in neonatal porcine skin fibroblasts. IGF-I stimulated DNA synthesis in skin fibroblasts in a concentration dependent manner. DNA synthesis was maximally stimulated by 5 to 20 fold at 5 nM IGF-I; half-maximal stimulation was observed at approximately 1 nM IGF-I. Co-incubation of IGFBP-3 with a maximally effective dose of IGF-I (10 nM) did not inhibit the stimulatory effects of IGF-I on DNA synthesis. In contrast, when IGFBP-3 at concentrations of 0 to 20 nM was co-incubated with 1 nM IGF-I, a bi-phasic dose response was observed with IGFBP-3 being inhibitory only at a 10 to 20 fold molar excess to IGF-I. Based on the approximately equal molar ratio of IGFBP-3:IGF-I present in the circulation of control and pST-treated pigs our results suggest that IGFBP-3 does not inhibit the mitogenic effects of IGF-I. In summary, these results indicate that the combination of IGFBP-3 with IGF-I optimizes mitogenic signalling via the type I IGF receptor and suggest that IGFBP-3 does not inhibit the effects of ST that are mediated by IGF-I.     

Signal-averaged electrocardiogram in patients with insulin-dependent (type 1) diabetes mellitus with and without diabetic neuropathy

The medical charts and operative files of 112 patients (combined inception cohort) with well to moderately differentiated invasive glottic squamous cell carcinoma presenting fixation (22) or impaired motion (90) of the true vocal cord (TVC) consecutively treated with cricohyoidoepiglottopexy (CHEP) at our institutions from 1972 to 1989 were retrospectively reviewed. A minimum 5-year follow-up was always achieved. The Kaplan-Meier 5-year actuarial survival, local recurrence, nodal recurrence, distant metastasis, and metachronous second primary tumor estimate for the entire group of patients were 84.7%, 5.4%, 6.4%, 1.2%, and 10.8%, respectively. The 5-year absolute and cause-specific survival rates were 85.5% and 94.1% for patients with fixation of the TVC and 81.3% and 96% for patients with impaired motion of the TVC. The 5-year actuarial local control rates for patients with fixation or impaired motion of the TVC were 95.4% and 94.4%, respectively. Local recurrence was statistically more likely in patients with positive margins (p = .007). Nodal recurrence was statistically more likely in patients with local recurrence (p = .005). Permanent tracheostomy related to postoperative laryngeal stenosis was requested in 2 patients. Aspiration-related completion total laryngectomy and/or permanent gastrostomy were never requested. Overall, local control and laryngeal preservation were achieved in 97.3%, and 95.5% of patients, respectively. At our institutions, the change from the conservative treatment modalities of radiotherapy and vertical partial laryngectomy to CHEP has brought about an increase in long-term survival, local control, and laryngeal preservation rates when compared to historical controls using vertical partial laryngectomy or radiotherapy.     

Decrease in insulin and insulin-like growth factor I (IGF-I) binding to erythrocytes from patients with cystic fibrosis

Guidelines for a healthy diet often recommend limiting dietary sugars and fats. Some researchers have called these aims mutually incompatible, suggesting that fat and sugar intakes, when expressed as percent dietary energy, are inversely linked. Others have argued that sugar, more specifically sucrose, acts as a vehicle for dietary fat and serves to suppress the overall quality of the diet. This study examined the relationship between age, sucrose and fat intakes, body mass index (BMI), and measures of dietary diversity and variety in a community-based sample of 837 French adults. Consistent with other studies, high consumption of added sucrose (in g/day or g/1000 kcal per day) was associated with higher consumption of energy and fat and lower consumption of vegetables and fruit. However, eating patterns were strongly influenced by age. High-sucrose consumers were significantly younger and had lower BMI values than did low-sucrose consumers, who were both older and had higher BMIs. High-sucrose diets had minimal effect on the diet diversity score and were associated with more varied diets, as evidenced by a higher dietary variety score.