PubMed Health⌕ Search

Biomedical subjects

F Minuto

Publications and source records attributed to F Minuto.

At least 55 records · Page 3Linked to original sources
PubMed1996

Intrafollicular insulin-like growth factor-II levels in normally ovulating women and in patients with polycystic ovary syndrome.

OBJECTIVE: To investigate intrafollicular insulin-like growth factor II (IGF-II) in patients affected with polycystic ovary syndrome (PCOS) in comparison with normal women. DESIGN: Insulin-like growth factor-II was determined in 103 follicular fluids (FF) from normally ovulating women and in 102 FF from patients with PCOS. Ribonucleic acid was extracted from granulosa cells of follicles obtained from control and PCOS patients and from tissue from polycystic ovaries. SETTING: Procedures were performed in a university laboratory. PATIENTS: Twenty-nine normally ovulating women and 19 patients with PCOS underwent ovulation induction for IVF-ET with LH-releasing hormone (LH-RH) analog and gonadotropins. Eleven of them, 4 to 8 months later, underwent ovulation induction with approximately the same dosage of gonadotropins plus a standard dosage of GH. MAIN OUTCOME MEASURES: Intrafollicular IGF-II, IGF-I, epidermal growth factor (EGF), transforming growth factor beta 2, (TGF-beta 2), inhibin, and steroids were evaluated by appropriate RIA, immunoenzymatic assay (EIA), and ELISA assays. The expression of the gene encoding IGF-II was analyzed by Northern blot. RESULTS: Intrafollicular IGF-II was lower in PCOS than in controls. Accordingly, IGF-II messenger RNA expression was lower in PCO than in normal granulosa cells. Several differences in FF IGF-I, EGF, inhibin, and TGF-beta 2 concentrations were observed between PCOS and controls. CONCLUSIONS: Both IGF-II and IGF-I were reduced in PCOS, confirming a possible role of an IGF imbalance in the development of this disease.

Adult↗
PubMed1996

Function of the GH/IGF-1 axis in healthy middle-aged male runners.

In an attempt to examine the effect of prolonged physical activity on the function of the GH/IGF-1 axis during the aging process in man, we have evaluated basal and GHRH (GHRH-29: 1 microgram/kg i.v. as a bolus) stimulated GH secretion as well as basal plasma IGF-1 levels in a group of 25 healthy runners (50-60 years, mean age 55.5 +/- 0.6) and 24 age-matched relatively sedentary normal controls (mean age 55.8 +/- 0.7). The runners had a minimum distance in kilometers of 26 km/week for at least 15 years, and competed in distances ranging from 16 km to the marathon. In runners, GHRH induced an increase of GH which was significantly higher (p < 0.001) than that observed in the age-matched controls. Baseline IGF-1 levels were significantly higher (p < 0.001) in trained runners (171 +/- 8.4 micrograms/1) compared to the controls (91.1 +/- 5.5 micrograms/1). These data show that in middle-age prolonged physical activity increases the function of the GH/IGF-1 axis. To clarify the possible mechanisms underlying the GH/IGF-1 secretory pattern in the runners, the GH responses to both single and combined administration of GHRH and arginine (ARG: 30 g infused over 30 min), a GH secretagogue likely acting via inhibition of hypothalamic somatostatin release, were investigated in 6 runners (mean age 55 +/- 1.9 years) and 6 controls (mean age 55 +/- 0.9 years). ARG clearly increased the GH response to GHRH in the controls, whereas it was unable to further potentiate the GH-releasing effect of GHRH in runners, thus suggesting that the increased GH responsiveness to GHRH might be due to an exercise-related decrease in endogenous hypothalamic somatostatinergic activity.

Aging↗
PubMed1995

Epidermal growth factor content of breast cyst fluids from women with breast cancer or proliferative disease of the breast.

The intracystic electrolyte content is generally used to identify different breast cyst subpopulations: cysts containing high K+ levels have been associated with an increased risk of subsequent breast cancer. In order to define whether other biochemical features of breast cyst fluid (BCF) might further explain such an increased risk, we determined the content of epidermal growth factor (EGF), a known mitogenic factor for normal and transformed breast epithelium, in cysts of women with breast cancer or proliferative lesions of the breast (atypical ductal or lobular hyperplasia and proliferative disease without atypia). Median intracystic EGF levels were significantly higher in patients with breast cancer or atypical hyperplasia than in cysts of women without any clinical or instrumental evidence of proliferative disease chosen as controls (p < 0.05 and p < 0.01, respectively). In patients affected by proliferative disease without atypia, intracystic EGF levels were not different either from controls or from the other study groups. No significant difference among groups was observed in the prevalence of Na+/K+ < 3 cysts, this being the most frequently observed type of cysts in all groups except in that with proliferative disease without atypia. No significant difference in EGF levels between cysts ipsilateral or contralateral to the biopsy was observed within each histological group. Our results indicate that EGF levels are higher in cysts aspirated from breasts with an associated proliferative pathology, either benign or neoplastic. The determination of intracystic EGF, combined with that of electrolyte content, might help to identify a subset of patients with gross cystic disease of the breast at potentially higher risk of developing breast cancer.

Adult↗
PubMed1995

Functions and regulation of the acid-labile subunit of the 150 K complex.

In normal subjects, the major form of circulating IGF is the GH-dependent 150 K complex. As demonstrated by gel-permeation chromatography, the acid-labile subunit (ALS) purified from human serum, incubated for 2 h at 20 degrees C with [125I]IGF-I and rIGFBP-3, is able to increase not only the molecular weight (mol. wt.) of the IGF-IGFBP-3 complex, but also the amount of IGF-I bound. In both charcoal and polyethylene glycol ligand binding assays, competitive binding curves for the displacement of [125I]IGF-I from rIGFBP-3 by increasing concentrations of unlabeled IGF-I showed an increased binding activity of rIGFBP-3 in the presence of ALS. The effect of ALS on rIGFBP-3 binding activity was dose dependent. In addition, ligand and immunoblot revealed that ALS and rIGFBP-3 are able to form a high mol. wt. complex in the absence of IGF peptide. On the basis of these data, ALS seems to have a more complex function than that of simply increasing the mol. wt of the IGF-IGFBP-3 complex. The regulation of ALS synthesis by rat hepatocytes in primary culture has also been evaluated by immunoblot. In agreement with the in vivo finding of an inhibitory effect of octreotide (a somatostatin analog) on the formation of the 150 K complex in acromegalic subjects, we could observe in vitro that octreotide produces a dose-dependent inhibition of ALS secretion into the hepatocyte conditioned medium. TGF-beta 1 was also inhibitory at high doses. On the contrary, we could not evidence any effect of IGF-I or IGF-II, while a small increase has been noted after incubation with T3.

Animals↗
PubMed1995

Effect of octreotide on circulating IGF-I chromatographic profile: evidence for an inhibitory action on the formation of the 150-kDa ternary complex.

OBJECTIVE: The increasing use in clinical practice of octreotide (a somatostatin analogue which inhibits the secretion of GH and other peptide hormones) led us to study the effects of this treatment on GH, insulin-like growth factors (IGF)-I and II and IGF-binding protein (IGFBP)-3, as well as on circulating IGFBP complexes in acromegalic patients. DESIGN: The circulating concentrations of GH, IGF-I, IGF-II and IGFBP-3 were measured in acromegalic patients before and after 3, 6, 9, and 12 months of treatment with octreotide (group I: n = 5), and compared with those found in a group of patients (group II) treated with bromocriptine (n = 3), cabergoline (n = 7) radiotherapy (n = 3) or surgical therapy (n = 2). In pools of serum obtained from patients treated with octreotide, dopaminergic drugs, surgery and radiation, before and after therapy, immunoreactive IGF-I and IGFBP-3 were also evaluated after Superdex 200 gel filtration in neutral conditions. RESULTS: Before treatment, the concentration of IGF-I and IGFBP-3 were above the normal range in all patients, while IGF-II levels were slightly reduced. After treatment with octreotide, IGF-I (P = 0.004), IGF-II (P = 0.02) and IGFBP-3 (P < 0.001) were significantly reduced as compared to basal levels. In subjects of group II, only IGF-I concentration was significantly reduced by the treatment (P = 0.02), and a negative correlation between IGF-I and IGF-II concentrations was found (r = -0.58, P < 0.0001). After gel filtration immunoreactive IGF-I and IGFBP-3 were found in the 150-kDa mol.wt. region in serum obtained from untreated patients and from treated patients of group II, while in the serum of octreotide-treated patients the IGF-I and IGFBP-3 peaks were shifted to the 60-kDa mol.wt. region, thus suggesting that the acid-labile subunit of the 150-kDa complex was drastically reduced. Since the GH concentrations in groups I and II were similar (M +/- SEM; 13.8 +/- 7.4 and 21.2 +/- 10.6 mU/l respectively), the marked reduction in acid-labile subunit in the octreotide treated patients can be explained by a direct inhibitory effect of somatostatin on the subunit. CONCLUSIONS: Octreotide exerts an inhibitory effect not only on IGF-I but also on IGF-II. The reduced formation of the 150-kDa complex probably causes an increased metabolic clearance rate of IGF peptides which can account for the reduced concentration of both IGFs after treatment with octreotide.

Acromegaly↗
PubMed1995

Effect of the acid-labile subunit on the binding of insulin-like growth factor (IGF)-binding protein-3 to [125I]IGF-I.

In normal subjects, the major form of circulating insulin-like growth factor (IGF) is the GH-dependent 150K complex. This complex is formed by the IGF peptide, the acid-stable binding protein IG-FBP-3, and the acid-labile subunit (ALS), which, although not binding IGF, appears to be necessary to reconstitute the complex in its natural form. The ALS was purified in our laboratory from human serum by ammonium sulfate precipitation, ion exchange chromatography using DEAE-Sephadex A-50, Concanavalin-A-Sepharose-4B chromatography, and two sequential gel filtrations by fast performance liquid chromatography. As demonstrated by gel permeation chromatography on fast performance liquid chromatography, incubation for 2 h at 20 C of this preparation with [125I]IGF-I and recombinant IGFBP-3 (rIGFBP-3) allows the reconstitution of a complex of about 150 kilodaltons. In these experimental conditions, the ALS is not only able to increase the mol wt of the complex, but also to greatly increase the amount of IGF-I bound; in the absence of ALS, radioactivity in the mol wt volume of the complexed forms was lower than that in the mol wt volume of the free form (percentage of total [125I]IGF-I: rIGFBP-3 alone, 15% and 44%; in the presence of ALS, 41% and 24%, respectively). In both charcoal and polyethylene glycol ligand binding assays, competitive binding curves for the displacement of [125I]IGF-I from rIGFBP-3 by increasing concentrations of unlabeled IGF-I showed an increased binding activity of rIGFBP-3 in the presence of ALS. The effect of ALS on rIGFBP-3-binding activity was dose dependent. These data show that the non-IGF-binding ALS subunit of the 150-kilodalton complex can play an important role in the regulation of IGF-I or IGF-II binding to rIGFBP-3 and, therefore, on the levels of free IGF peptide, possibly by inducing conformational changes in rIGFBP-3. In addition, ligand and immunoblot reveal that ALS and rIGFBP-3 are able to form a high mol wt complex in the absence of IGF peptide. On the basis of these data, ALS seems to have a more complex function than that of simply increasing the mol wt of the IGF-IGFBP-3 complex.

Binding, Competitive↗
PubMed1995

Hypoglycemia in a dog with a leiomyoma of the gastric wall producing an insulin-like growth factor II-like peptide.

A 12-year-old mixed-breed male dog was referred to the Clinica Medica Veterinaria of Bologna University for recurrent episodes of seizures due to hypoglycemia with abnormally low plasma insulin levels (18 pmol/l). Resection of a large leiomyoma (780 g) of the gastric wall resulted in a permanent resolution of the hypoglycemic episodes. Insulin-like growth factors I and II (IGF-I and -II) were measured by RIA in serum before and after surgery and in tumor tissue. Results were compared to the serum concentration of 54 normal and to the tissue concentration observed in eight non-hypoglycemic dog gastric wall extracts. Before surgery, circulating immunoreactive IGF-I was 0.92 nmol/l, which is significantly lower than the control values (16.92 +/- 8.44 nmol/l, range 3.53-35.03), while IGF-II was 152 nmol/l, which is significantly higher than the control values (42.21 +/- 3.75, range 31.99-50.74). After surgery, IGF-I increased to 6.80 nmol/l while IGF-II decreased to 45.52 nmol/l. Tumor tissue IGF-II concentration was higher than normal (5.66 nmol/kg tissue as compared to a range in normal gastric wall tissue of 1.14-3.72 nmol/kg), while IGF-I was 0.08 nmol/kg tissue, which is close to the lowest normal value (range in controls, 0.08-1.18 nmol/kg). Partial characterization of IGF-II immunoreactivity extracted from tissue evidenced a molecular weight similar to that of mature IGF-II, thus excluding that peptide released by the tumor is a precursor molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Presence of immunoassayable transforming growth factor-beta 1 (TGF-beta 1) in breast cyst fluid (BCF): relationship with the intracystic electrolyte and epidermal-growth-factor (EGF) content.

We evaluated the presence and distribution of transforming growth factor-beta 1 (TGF-beta 1) in breast cyst fluid (BCF), and its relationship with intracystic epidermal growth factor (EGF). EGF and TGF-beta 1 were determined by radioimmunoassay on 47 BCFs (27 of the Na+/K+ < 3 type and 20 of the Na+/K+ > 3 type). As expected, EGF levels were inversely correlated with the Na+/K+ ratio, and were consequently higher in Na+/K+ < 3 cysts as compared with Na+/K+ > 3 cysts, (p < 0.005). By contrast, TGF-beta 1 levels were directly correlated with the Na+/K+ ratio (p < 0.01), being higher in Na+/K+ > 3 cysts, though not significantly (p = 0.057). A significant negative relationship was found between EGF and TGF-beta 1 concentration. When the analysis was performed separately in the 2 cyst sub-populations, EGF and TGF-beta 1 were found to be negatively and significantly correlated in Na+/K+ < 3 cysts only (p < 0.01). Our results demonstrate that Na+/K+ < 3 cysts contain high levels of EGF, a growth-stimulating factor, and very low levels of TGF-beta 1, a growth-inhibiting factor. This may provide an explanation for the higher risk of breast cancer observed in women with Na+/K+ < 3 cysts. Our results also suggest that EGF accumulation in this type of cysts might be regulated by TGF-beta 1.

Epidermal Growth Factor↗
PubMed1994

Assessment of growth hormone insulin like growth factor-I axis in Down's syndrome.

As GH therapy has been reported to increase growth velocity in children with Down's syndrome (DS), we studied the GH-IGF-I axis in some DS patients affected by growth retardation without serious congenital malformation, malnutrition or pathological thyroid or adrenal function. IGF-I and IGF-II were evaluated in 39 patients in basal conditions. The patients were subsequently divided into two groups with respect to the IGF-I basal value: Group 1 (GR 1) consisting of patients with abnormally low basal IGF-I concentration as compared to age matched control subjects, group 2 (GR 2) consisting of patients with IGF-I in the normal range. In 6 GR 1 patients and 12 GR 2 patients we evaluated GH and IGF-I concentrations after stimulation with arginine (0.5 g/kg bw), and recombinant GH (4 IU im). In the same patients, GH radioreceptor assay and serum GH-binding protein were evaluated. In all patients IGF-II proved normal (534 +/- 23 ng/ml; mean +/- SE), while IGF-I was pathological in 36% of subjects. The cause of the defective IGF-I secretion in these patients does not seem to depend on an impaired GH axis, as no significant difference in arginine-stimulated GH peak values was seen between GR 1 (29.6 +/- 5.3 ng/ml) and GR 2 (15.1 +/- 2.24 ng/ml). IGF-I concentration evaluated 12, 24, and 48 h after arginine stimulation was significantly increased only in GR 2 patients (peak value: 0.95 +/- 0.1, p = 0.0003 vs baseline; GR 1: 0.34 +/- 0.05 U/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Carrier Proteins↗
PubMed1993

In vivo and in vitro effect of growth hormone on estradiol secretion by human granulosa cells.

GH therapy increases the ovarian response to gonadotropin stimulation in women presenting with ovaries that are relatively resistant to conventional gonadotropin therapy. As it is not completely certain whether GH modulates the actions of FSH on granulosa cells directly or via insulin-like growth factor-I (IGF-I) production, we studied its effect on steroid release by human granulosa cells obtained from subjects affected by unexplained or male factor infertility. In all subjects, superovulation for in vitro fertilization/embryo transfer was induced by treatment with gonadotropins or GH plus gonadotropins combined. The effects of the different in vivo treatments were evaluated in the conditioned medium obtained after the first 24 h of incubation; granulosa cells from patients treated with GH released higher amounts of estradiol and progesterone into the medium than did granulosa cells from patients treated with gonadotropins alone. When the release of steroid due to the in vivo treatment was exhausted, cells were subjected to increasing concentrations of GH in the presence or absence of 200 nmol anti-IGF Sm 1.2 monoclonal antibody (MoAb) or the antitype I receptor alpha IR3 MoAb. The results revealed that GH stimulates estradiol production in a dose-dependent fashion, and the presence of the MoAbs drastically reduces the GH effect. These data demonstrate that the established stimulatory effect of GH on ovarian function is dependent not only on the increased levels of circulating IGF-I, but also on a direct effect of GH on granulosa cells, which seems to be mediated at least in part by the autocrine action of IGF, particularly IGF-II. In fact, chromatographic analysis of medium conditioned by human granulosa cells revealed that these cells clearly produce IGF-II and IGF-binding proteins and only small amounts of IGF-I. Since GH appears to be able to increase the in vitro effect of both IGF-I and IGF-II, we can hypothesize a sensitization of the granulosa cells to the IGF-II produced by the cells themselves, which acts through the IGF-I receptor.

Adult↗
PubMed1993

Somatotropic function in short stature: evaluation by integrated auxological and hormonal indices in 214 children. The Italian Collaborative Group of Neuroendocrinology.

GH secretion was evaluated in 214 children and adolescents (age, 5-16 yr; 160 males and 54 females) with short stature (height, < or = 5th percentile) by assessing mean spontaneous overnight GH concentration (normal values, > or = 3 and 3.9 micrograms/L for prepubertal and pubertal subjects, respectively) and responsiveness to stimulation with GH-releasing hormone combined with pyridostigmine (normal peak values, > or = 20 micrograms/L). Plasma insulin-like growth factor-I (IGF-I) was also measured. According to their GH secretory status, children were grouped as follows: group I, 154 subjects with normal spontaneous and stimulated GH (43 slow-growing and 111 normally growing); group II, 39 subjects with low spontaneous, but normal stimulated, GH (27 slow-growing and 12 normally growing); group III, 18 slow-growing subjects with low spontaneous and stimulated GH; and group IV, 3 subjects with normal spontaneous, but low stimulated, GH. The following conclusions were drawn. 1) Forty-five slow-growing subjects (21% of the total sample) had GH deficiency; 27 (12.6%) belonged to group II (with a preserved GH pituitary reserve, denoting a hypothalamic dysfunction) and 18 (8.4%) to group III (with a reduced GH pituitary reserve). 2) Forty-three slow-growing children in group I had normal GH secretion but low mean IGF-I, which may indicate nutritional problems or a biologically hypoactive GH molecule. 3) The remaining 111 subjects in group I (52%), with normal growth rate, but low mean parental height, were considered as having familial and/or constitutional short stature. GH responses after pyridostigmine plus GH-releasing hormone were normal in all children with a normal growth rate. These findings show that besides clinical evaluation, the assessment of spontaneous GH secretion, GH pituitary reserve, and IGF-I concentration allows proper pathophysiological characterization of short stature. By this approach, the frequency of GH deficiency in our sample was higher than commonly thought.

Adolescent↗
PubMed1993

Long-term endocrine effects of administration of either a non-steroidal antiandrogen or a luteinizing hormone-releasing hormone agonist in men with prostate cancer.

The claimed ability of non-steroidal antiandrogens to preserve libido and sexual potency is sought as a potential improvement in the palliative management of prostate cancer. A critical issue for the clinical use of these compounds is, however, the reported evidence in the rat of an excessive increase in testosterone concentrations as a consequence of the androgen negative feedback interruption. On the other hand, the recovery of testicular function after long-term inhibition by luteinizing hormone-releasing hormone (LHRH) analogs is also an important concern in view of the proposed use of these compounds for the treatment of several non-malignant conditions. We addressed these issues by studying the long-term endocrine effects induced by the administration of either the non-steroidal antiandrogen nilutamide or the depot preparation of D-Trp6-LHRH in men with prostate cancer. Treatment with the antiandrogen induced a marked increase in gonadotropin levels, LH concentrations rising from a mean (SEM) of 17.5 +/- 1.6 to a maximum of 56.6 +/- 6.9 kU/l (p < 0.001), while mean testosterone and 17 beta estradiol-concentrations rose only by about 50% and 70% over pretreatment values, testosterone levels reaching a plateau after 1 month of treatment. In the subjects treated with the LHRH agonist, 6 months after discontinuation of long-term administration the mean (+/- SEM) LH had risen to 36.9 +/- 6.8 IU/l while mean testosterone levels were still as low as 1.7 +/- 0.7 and rose only to a maximum of 4.2 +/- 1 nmol/l after high-dose human chorionic gonadotropin loadings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

In vitro paracrine regulation of human keratinocyte growth by fibroblast-derived insulin-like growth factors.

Human keratinocytes isolated from a skin biopsy and cultured in vitro on a feeder-layer of irradiated fibroblasts reconstitute a stratified squamous epithelium suitable for grafting onto patients suffering from large burn wounds. Since conditioned medium from 3T3-J2 cells can partially substitute for the intact feeder-layer, we studied the possible involvement of insulin-like growth factors acting in a paracrine fashion. IGFs were measured (after Sephadex G-50 gel-chromatography in acid conditions) in media conditioned by a feeder-layer of lethally irradiated 3T3-J2 fibroblasts on which keratinocytes were grown. Immunoreactive (IR) IGF-I, IGF-II, and IGF binding activity were present in the medium conditioned by the feeder-layer. The medium conditioned by keratinocytes showed nearly undetectable amounts of IR IGF-I and IGF-II, suggesting that keratinocytes are unable to synthesize IGFs peptides. Recombinant IGF-I and IGF-II, and conditioned medium from 3T3-J2 cells, caused a dose-dependent increase of 3H-thymydine incorporation in cultured keratinocytes. The stimulatory effect of IGF and of 3T3-J2 conditioned medium was inhibited by the MoAb Sm 1.2, which recognizes both IGF-I and IGF-II but not insulin, and by the MoAb alpha IR-3, which is a specific antagonist of type-I IGF receptor. Fetal mouse-derived 3T3-J2 cells and adult human skin fibroblasts were equally able to sustain keratinocyte growth and in both cases addition of Sm 1.2 MoAb causes a 50% decrease in the keratinocyte number. When the non-IGF-producing BALB/c 3T3 cells were used as a feeder-layer, the keratinocytes number was similar to that observed with 3T3-J2 and with human fibroblasts plus the Sm 1.2 MoAb. IGF-I and IGF-II restored the BALB/c 3T3 growth promoting activity to the level of 3T3-J2 and of normal human fibroblasts. Our results suggest that fetal mouse 3T3-J2 and human fibroblasts synthesize IGF peptides, while keratinocytes do not. Fibroblast-derived IGFs stimulate keratinocyte growth in a paracrine fashion, suggesting their role in the regulation of keratinocyte proliferation in skin growth and in wound healing.

Animals↗
PubMed1992

Effect of epidermal growth factor on insulin-like growth factor-I (IGF-I) and IGF-binding protein synthesis by adult rat hepatocytes.

Growth hormone has been established as a primary regulator of IGF-I gene expression in adults, not only in liver but also in many extrahepatic tissues. We considered the possibility that IGF-I production by adult rat liver could also be stimulated by epidermal growth factor (EGF), a peptide known to be involved in liver regeneration. Chromatographic analysis performed after acid treatment of conditioned media revealed the presence of both immunoreactive (IR) IGF-I and IGF binding protein (IGFBP). Both IR IGF-I and IGFBP were present in the conditioned medium of adult rat hepatocytes in basal conditions. The stimulation of IGF-I and IGFBP secretion by EGF appears to be dose-dependent with a significant increment already evident at 5 nM. That EGF stimulates secretion is supported by the finding that IGF-I and IGFBP-1 mRNA levels are increased after EGF supplementation. We conclude that adult rat hepatocytes spontaneously produce IGF-I and IGFBP, and that EGF is able to increase their synthesis and secretion. This non-growth hormone-dependent regulation of IGF-I and IGFBP-1 production by adult rat hepatocytes in culture indicates an important autocrine/paracrine role for IGF-I, particularly during liver regeneration after extensive organ mass loss.

Animals↗
PubMed1992

Effects of growth hormone administration in addition to gonadotrophins in normally ovulating women and polycystic ovary syndrome (PCO) patients.

Follicular fluid sex-steroids, insulin-like growth factor-I (IGF-I), IGF-I binding protein (IGF-I-BP) and epidermal growth factor were investigated in patients with polycystic ovaries and normally ovulating women, following ovulation induction with gonadotrophins or growth hormone plus gonadotrophins. Growth hormone supplementation enhanced the ovarian response to gonadotrophins, and significantly increased follicular fluid IGF-I in both groups, without affecting follicular fluid epidermal growth factor; growth hormone supplementation significantly decreased follicular fluid androstenedione in both groups.

Adult↗
PubMed1992

[Insulin-like growth factors in human pathology].

IGFs-I and -II are single chain polypeptides (70 ad 67 aa respectively) structurally similar to proinsulin, synthesized ubiquitously and circulating carried by specific binding proteins. The IGFs act through two types of specific membrane receptors: the so called "type 1" or IGF-I receptor, and the "type 2" or IGF-II receptor. In physiological conditions IGF-I is correlated with GH secretion. However it is also influenced by other hormonal and non-hormonal factors. Little is known about the physiological significance of IGF-II, whose concentration, at variance with IGF-I, is not increased in acromegalic subjects. It has been recently postulated that IGF-II has a critical role in prenatal growth, while IGF-I exerts its action after birth. IGF-I is important in the clinical evaluation of growth defects and of acromegalic patients. As to growth defects an overlapping of values is reported between normal and hypopituitary subjects under 5-6 years of life. However, although it is possible that a normal subject presents with a reduced IGF-I concentration, it never happens to find a hypopituitary subject with normal values. It is, therefore, possible to establish a cut-off value (100 micrograms/l in our experience) over which the occurrence of hypopituitarism is excluded. On the contrary IGF-I concentration is extremely useful in the evaluation of acromegaly, in particular to evidence the disease activity status. Moreover the IGF-I concentration seems to be useful to evaluate the nutritional status, particularly in association with serum transferrin, in subclinical conditions and in the monitoring of the nutritional therapy.

Acromegaly↗