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β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is an NADPH-dependent reductase that converts cortisone to cortisol in adipose tissue. We previously reported that GH and IGF-I decrease 11β-HSD1 activity and mRNA levels in adipocytes. Hexose-6-phosphate dehydrogenase (H6PDH) is involved in the production of NADPH, which is a coenzyme for 11β-HSD1. The aim of the present study was to clarify further the mechanism of repression of 11β-HSD1 activity by GH using linsitinib, an IGF-I receptor inhibitor. The suppression of 11β-HSD1 mRNA by IGF-I was attenuated in the presence of 1 μM linsitinib (17.2% vs. 53.3% of basal level, P

The somatostatin analog lanreotide Autogel has proven to be efficacious for treating acromegaly in international studies and in clinical practices around the world. However, its efficacy in Japanese patients has not been extensively evaluated. We examined the dose-response relationship and long-term efficacy and safety in Japanese patients with acromegaly or pituitary gigantism. In an open-label, parallel-group, dose-response study, 32 patients (29 with acromegaly, 3 with pituitary gigantism) received 5 injections of 60, 90, or 120 mg of lanreotide Autogel over 24 weeks. Four weeks after the first injection, 41% of patients achieved serum GH level of

In Japan, the growth hormone (GH) assay has been standardized since April 2005 through use of a uniform recombinant human GH (rhGH) standard. Since then, GH values measured using the rhGH standard have been approximately 40% lower than previous values measured using kit standards based on the WHO standards for hGH of pituitary origin. However, the Japanese criteria for evaluating treatment outcomes for acromegaly have remained the same: a nadir GH during a 75 g OGTT1 µg/L is considered cured, 1≤GH2.5µg/L is considered inadequately controlled, and ≥2.5 µg/L is considered poorly controlled, instead of these levels were lowered to 60%, i.e. from 1 to 0.6 µg/L for cured and from 2.5 to 1.5µg/L for inadequately controlled (termed as "newly proposed criteria" in this study). We investigated the effects of standardization of the GH assay on the evaluation of post-surgical disease activity in 50 patients with acromegaly (M/F 19/31, 21-72 yr.). Post-surgical nadir GH levels during OGTT were positively correlated with the IGF-I SD score 3 months after TSS. Five of 6 patients whose post-surgical nadir GH levels ranged between 0.6 and 1 µg/L had normal serum IGF-I levels 3 months after TSS. Rates of improvement in glucose metabolism did not differ when patients were classified based on the present criteria vs. the newly proposed criteria. In conclusion, the current Japanese remission criteria for acromegaly still accurately reflect post-surgical disease activity in most patients, though long-term observation is still required.

Patients with growth hormone (GH) deficiency (GHD) have a clinical feature of visceral adiposity and it has been reported that these patients have an increased active cortisol (F)/inactive cortisone (E) metabolite ratio. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is an enzyme expressed in liver and adipose tissue that acts principally as a reductase converting E to F. In the present study, we investigated the effects of GH or IGF-I on the activity of 11beta- HSD1 in 3T3-L1 cell homogenates and its mRNA expression. First, we showed that 11beta-HSD1 activity and mRNA levels were low in preadipocytes and increased throughout the process of adipogenesis. When fully differentiated adipocytes were treated with GH for various times, the activity of 11beta-HSD1 was significantly decreased after 4 h and 8 h but was restored to basal levels after 24 h. After 8 h of GH stimulation, 11beta-HSD1 mRNA levels were decreased compared with basal levels. IGF-I treatment of adipocytes resulted in rapid decreases in 11beta-HSD1 activity as well as mRNA levels; however, IGF-I treatment for 24 h increased 11beta-HSD1 activity. In long-term cultured adipocytes, GH or IGF-I showed only inhibitory effects on 11beta-HSD1 activity. In conclusion, 11beta-HSD1 activity was suppressed by GH or IGF-I in differentiated adipocytes, probably due to a reduction of 11beta-HSD1 mRNA levels. These data suggest that under the conditions of low GH or IGF-I concentrations, 11beta-HSD1 activity in adipose tissue is maintained at high levels, leading to an increase in active cortisol that induces adipogenesis and/or lipogenesis. Thus, visceral adiposity in patients with GHD might be related to increased 11beta-HSD1 activity.

It has been reported that patients with acromegaly may have an increased risk of developing several types of cancers, such as colorectal, breast and prostate tumors. However, some reports do not support these findings and therefore the prevalence of cancers in patients with acromegaly remains controversial. In this study, we determined the prevalence of benign and malignant neoplasms in patients with acromegaly. A retrospective chart analysis was performed on 140 patients with active acromegaly who had attended our outpatient clinic (M/F 54/86, age 55 +/- 25 yr, range 21-86). Colon cancer was found in 10 patients, thyroid cancer in 5, breast cancer in 4 and gastric cancer in 2. When compared with the local population, the standardized incidence ratios (SIRs) for thyroid cancer in patients with acromegaly were 61.74 (95% confidence interval (CI): 0.51-114.63) for females and 272.4 (95% CI: 29.12-876.71) for males. The SIRs for colon cancer in the acromegalic patients were 17.4 (95% CI: 4.74-44.55) for females and 19.0 (95% CI: 5.18-48.64) for male patients in comparison with the local population. Of the benign tumors, multinodular goiter and colonic, gastric and gallbladder polyps were observed in 57% (47/83), 40% (35/87), 23% (10/43), and 14% (11/77) [corrected] of the patients, respectively. This study suggested that patients with acromegaly have an increased risk of colon cancer and polyps. Moreover, it is speculated that the risk for thyroid cancer is increased in male patients. It is therefore recommended that patients with acromegaly should undergo screening colonoscopy and ultrasonography of the thyroid.

GH therapy was approved in 2006 for treatment of adult growth hormone deficiency (GHD) in Japan. Until then, GH was used only to treat short stature in children with GHD and the treatment was stopped when the final height was reached. In the present study, we investigated metabolic co-morbidities experienced by adults with childhood-onset (CO) GHD after the cessation of GH. Forty-two patients with COGHD (M/F 22/20, age at follow up when the retrospective analysis was carried out: 18-52 yr) treated with GH in childhood were studied. We reviewed the medical records of these patients to determine the metabolic co-morbidities that developed after cessation of GH. The median age was 19 yrs (range: 14-38) at cessation of GH, and the following co-morbidities were observed: hypertriglyceridemia in 15 (41%) patients, non-alcoholic fatty liver disease (NAFLD) in 11 (29%) patients, hypercholesterolemia in 10 (26%) patients, diabetes mellitus (DM) in 4 (10%) patients, and hypertension in 1 (2.4%) patient. The median BMI when these complications became overt was 23.5 kg/m(2) for those with hypertriglyceridemia, 26.0 kg/m(2) for those with NAFLD, 20.9 kg/m(2) for those with hypercholesterolemia, and 27.2 kg/m(2 ) for those with DM. More than two co-morbidities were experienced by 32% of men and 30% of women. In conclusion, adults with COGHD after the cessation of GH have multiple metabolic co-morbidities. Lifelong GH replacement might be important for improving the overall metabolic profiles in these patients.

In TSH-secreting pituitary adenomas (TSHoma), octreotide (OCT) therapy reduces tumor size and TSH secretion in some cases but not in others. As OCT acts through various types of somatostatin receptors (SSTRs), the different responses of TSHoma to OCT might be explained by the differences of SSTR expression. We therefore studied the expression of subtype-specific SSTR mRNA transcripts in tumor tissues by RT-PCR. Type 2 (SSTR2) mRNA transcripts were detected in all 8 tumors but those of SSTR3 and SSTR5 were demonstrated only in 5 of them. Serum TSH levels were decreased by OCT administration test in all patients but OCT therapy was effective in two patients out of three. SSTR5 mRNA was detected in two tumors from the responder, but not in one tumor that was resistant to OCT. These observations suggest that the temporal decrease of TSH by OCT may be mediated by SSTR2, and that the long term response to OCT therapy may be related with the expression of SSTR5. Therefore, the expression of SSTR5 in TSHoma may be a useful marker for predicting the outcome of the therapy, but further studies with larger numbers of patients are necessary.

In this study, we sent questionnaires to doctors treating severe short stature with severe GH deficiency (GHD) (height SDS (HtSDS) below -4 and all peak GH to provocative stimuli below 2 micro/L) (abbreviated as Severe Case), and obtained effective replies of 51 cases. The clinical characteristics, etiologies, and pathophysiology of these patients were examined. Among the 51 Severe Cases no consanguinity was observed, 44 were IGHD (24 males and 20 females), 3 were GH-1 gene deletion, 2 were Pit-1 gene mutation, and 2 were achondroplasia. HtSDS in these Severe Cases was already remarkably low at 12 (-3.0) and 24 months old (-3.9), while their birth weight and birth length were within normal ranges. Among 44 patients with IGHD, 12 were isolated GHD, and the remaining 32 were combined pituitary hormone deficiency (CPHD). Pituitary MRI was undergone in 25 idiopathic GHD, and abnormal findings (pituitary atrophy, interruption of stalk, and ectopic posterior lobe) were observed in 21 patients with CPHD. More than half of these patients had the history of breech delivery. Three patients with GH-1 gene mutation showed normal pituitary MRI, whereas one of two patients with Pit-1 mutation showed pituitary atrophy and narrowing of pituitary stalk. In conclusion, Severe Cases tended to have CPHD, and the incidence of Severe Case was only 0.6% of total IGHD. Although GHD due to genetic disorders is considered to be extremely rare (0.06% of total IGHD), the incidence reaches high levels (9.8%) among Severe Cases. Growth disorders in these Severe Cases seem to occur soon after delivery. Much earlier diagnosis and hGH treatment are desirable to attain better final height in the Severe Cases. GH-1 and Pit-1 gene analyses are crucial, when genetic abnormalities other than achondroplasia are suspected.

We describe a rare case of hypoglycemia associated with a high molecular weight form of insulin-like growth factor II (big IGF-II) produced during the development of malignant fibrous histiocytoma (MFH). A 66-year-old man was referred to our department for further evaluation of hypoglycemia. At the age of 59, he had been diagnosed as having a MFH in the retroperitoneum, and underwent incomplete resection of the tumor. He had no symptoms of hypoglycemia at that time. Within the last few years, he developed symptoms of hypoglycemia in the early morning. Computerized tomography scans of the abdomen showed multiple tumors around the peritoneum and the liver. Serum insulin levels were decreased although no other hormonal deficiencies were observed. Serum IGF-II levels were elevated as a result of big IGF-II production. Taken together, these results indicated that hypoglycemia in this patient was associated with the production of big IGF-II by the MFH. The most effective therapeutic modality in patients with non-islet cell tumor hypoglycemia is resection of the tumor. In our case, as complete resection was impossible, dexamethasone and glucagon were administered and proved to be effective for preventing hypoglycemia.

In serum, insulin-like growth factors (IGFs) are primarily present as a approximately 150 kDa ternary protein complex, which consists of IGFs, IGF binding protein-3 (IGFBP-3), and acid-labile subunit (ALS). Like IGF-I and IGFBP-3, serum levels of ALS depend on growth hormone (GH). To date, the diagnostic relevance of ALS in adult GH deficiency (GHD) has remained uncertain. To clarify the clinical utility of ALS measurement in adults, we measured serum ALS levels in patients with adult GHD or acromegaly. We also measured the levels of serum IGF-I and IGFBP-3 in these patients to compare the utility of ALS with IGF-I and IGFBP-3 as a marker of GH secretion. Serum ALS was measured by radioimmunoassay (RIA) kit, and serum IGF-I and IGFBP-3 were measured by immunoradiometric assay (IRMA) kits in 56 patients with adult GHD (adult-onset (AO)/child-onset (CO), 13/43) and 43 patients with acromegaly. Serum ALS levels were less than 5th percentile in 40 of 56 (71%) patients with adult GHD (32/43 (74%) for CO and 8/13 (62%) for AO), and more than 95th percentile in 38 of 43 (88%) patients with acromegaly, respectively. Serum IGF-I levels were less than -1.96 SD in 43 of 56 (77%) patients with adult GHD (35/43 (81%) for CO and 8/13 (62%) for AO) and more than +1.96 SD in 42 of 43 (98%) patients with acromegaly, respectively. Serum IGFBP-3 levels were less than -1.96 SD in 51 of 56 (91%) patients with adult GHD (42/43 (98%) for CO and 9/13 (69%) for AO) and more than +1.96 SD in 31 of 43 (72%) patients with acromegaly, respectively. These data suggested that measurement of ALS offers no advantage over measurements of serum IGF-I and IGFBP-3. Furthermore, our results indicate that serum IGFBP-3 is the most suitable marker of GH secretion for adult GHD, especially CO, while IGF-I may be the most useful in acromegaly.

The Foundation for Growth Science has been controlling the use of GH by its registration system, which includes a scoring system for the eligibility for GH treatment according to the diagnostic criteria for GH deficiency (GHD) established by the Study Group for Hypothalamo-pituitary Disorder of the Ministry of Health and Welfare. Until 1995, 28,876 patients with GHD (19,432 boys and 9,444 girls) had been registered as eligible for GH treatment. The number of patients registered in a year increased gradually till 1990 due to the unlimited hGH supply by recombinant techniques and the change in the criteria for GH treatment and the number registered became stable after 1990. The frequency of GH-treated patients is calculated to be 55.2/100,000 persons (72.2/100,000 in boys and 37.1/100,000 in girls) in patients born between 1960 and 1990. The highest frequency was 148.4/100,000 persons (191.7/ 100,000 boys and 103.7/100,000 girls) in 1981, when 2,278 patients (1,508 boys and 770 girls) were born. Eligibility for GH treatment is assessed according to the scoring system which is basically dependent on peak GH values in provocation tests so that standardization of GH values measured with the various commercial GH kits is required to avoid inequality of patients' access to the treatment. In samples obtained by GRF test in 10 normal volunteers, hGH was measured with seven human GH (hGH) kits at a laboratory center. Since the RIA value has been used historically for the diagnosis of GHD, the mean of two RIA measurements was selected as the basis for the standardization procedure and the linear regression formula was used for each hGH kit. After the freely available supply of hGH obtained by recombinant DNA techniques, the role of the Foundation for Growth Science has changed to avoid hGH abuse. Even with this regulation, the frequency of registered patients may indicate a tendency to GH overuse.

With a euglycemic hyperinsulinemic clamp method, whole-body insulin resistance was assessed in 6 cases with acromegaly associated with diabetes mellitus before and after transsphenoidal adenomectomy. The glucose infusion rate (GIR) correlated well with the plasma IGF-I level but poorly with that of GH. Further improvement in insulin sensitivity occurred 3-4 months after operation without substantial changes in plasma levels of both GH and IGF-I or glycemic control. These results indicate that GH excess can induce insulin resistance in association with plasma IGF-I and also through undefined secondary effect.

Insulin-like growth factor II (IGF-II) in serum and tumor extracts from five patients with non-islet-cell tumor hypoglycemia (NICTH) has been characterized. These tumors contained large quantities of IGF-II (2.4-14.2 micrograms/g tissues). The serum IGF-II levels in four of five patients were a little high and the serum IGF-I levels in five patients were low. The serum IGF-II/IGF-I ratios in these patients ranged from 24.1 to 64.2, and the values were significantly greater than those in normal subjects (1.7-7.1). When the sera were gel-filtered on a Sephacryl S-200 column under neutral conditions, the proportion of the free form of IGF-II was not increased. However, in four of five patients, an abnormal IGF-II-IGF binding protein complex was found. When serum IGF binding proteins (IGFBPs) were analyzed by Western ligand blotting, serum IGFBP-2 increased in these patients. When the tumor extracts and sera were gel-filtered on a Biogel P-60 column under acidic conditions, the majority of IGF-II in these sera was a big form of IGF-II. As compared to authentic IGF-II, insulin receptor reactivities and IGF-II receptor reactivities of tumor extracted IGF-II increased in two of three patients. These data indicate that in patients with NICTH, heterogenous IGF-II is produced in respect of size and bioactivities, and that the characteristics of IGF binding protein are altered. Thus, to find IGF-II producing tumors among extrapancreatic tumors associated with hypoglycemia, the quality of IGF-II as well as the quantity should be studied.

Insulin--like growth factors bind to specific binding proteins (IGFBPs) in serum and tissues. At present, six different IGFBPs have been characterized. Recent studies suggest that IGFBPs act as a reservoir for IGFs but also modulate the bioavailability of IGFs. Binding protein for growth hormone (GH) in serum has been recognized recently. Interestingly, the high affinity GH binding protein (GHBP) is identical with the extracellular domain of GH receptor and is absent in patients with Laron-type dwarfism, suggesting that serum GHBP might serve as a marker for the GH receptor in tissue. In this short review, updated information on serum GHBP and IGFBP is presented.

Specific insulin-like growth factor I (IGF-I) receptors on human promyelocytic leukemia cell line (HL-60) were identified and characterized. [125I]IGF-I specifically bound to the cells, and [125I]IGF-I binding to the cells was displaced by unlabeled IGF-I in a dose dependent manner. [125I]IGF-I binding to the cells were displaced by multiplication stimulating activity (MSA) and porcine insulin, with potencies that were 10 and 100 times less than that of IGF-I, respectively. By an affinity labeling technique, IGF type I receptors were found to be present on the HL-60 cells. After the cells were differentiated to the macrophage-like cells by 12-o-tetra-decanoyl-phorbol-13-acetate (TPA) and 1,25-dihydroxy-vitamin D3 (1,25(OH)2D3), [125I]IGF-I binding to the cells decreased significantly. By Scatchard analysis, it was found to be due to a decrease in the number of IGF-I receptors. Thus, the differentiation of HL-60 cells to the macrophage-like cells was accompanied by a decrease in IGF-I receptors.

Degradative activities of somatomedin A (SMA) have been examined in various tissue homogenates of rat using trichloracetic acid precipitable radioactivity of 125I-SMA. Kidney and testis showed higher specific activities and liver and brain lower activities. They were dependent on SH reagents; 0.5 mM HgCl2 inhibited the degradative activity of liver completely and 1 mM dithiothreitol (DTT) augmented the activity slightly. The activities in liver were separated by differential centrifugation; about 90 per cent of the total activity in the whole homogenate was recovered in the supernatant fraction at 100,00 x g for 60 min, and 10 per cent in the precipitate. The pH profile of each fraction was different; that of the supernatant showed a single peak at pH 7.4 and that of the pellet revealed two peaks at pH 5.9 and 7.4. However, both fractions showed similar SH-dependency.

Synthetic human pancreatic growth hormone-releasing factor (hpGRF-44) was infused intravenously at a constant rate of 2.5 micrograms/min for 180 minutes in 3 normal boys of short stature. Plasma GH levels reached a peak at 60-120 min with a mean value (+/- SEM) of 69.1 +/- 14.3 ng/ml, and then, declined gradually in spite of continuous hpGRF-44 infusion up to 180 minutes. Similarly, constant infusion of hpGRF-44 at a rate of 2.5 micrograms/min in 5 normal but short boys for 90 minutes, together with an iv bolus injection of hpGRF-44 (2 micrograms/kg) administered at 0 and 90 minutes, elicited a prompt rise in plasma GH 15-30 minutes after the first bolus but no significant elevation of GH was observed after the second bolus. In contrast, when two iv bolus injections of hpGRF-44 (2 micrograms/kg) were given in 4 normal boys with short stature at 0 and 90 minutes, respectively, significant elevation of plasma GH was found after each bolus. These results suggest that under constant infusion of GRF the pituitary experiences a down-regulation after the initial peak of GH response, possibly due to desensitization to GRF.

We studied the plasma GH profiles in 6 patients with Turner's syndrome and 6 normal girls of short stature by sampling every 20 min for 24 hours. We observed episodic secretion of GH in these subjects. The mean plasma 24 h GH level in patients with Turner's syndrome was 3.6 +/- 1.4 (SD) ng/ml which was significantly lower than that of normal short girls (7.1 +/- 2.2 ng/ml, p less than 0.01). The GH secretion during both nighttime and daytime was decreased in the patients with Turner's syndrome, however the number of pulses did not differ significantly. There were no correlations between the mean plasma 24 h GH level on one hand and peak GH level obtained after GH provocative test and plasma somatomedin C on the other. Plasma FSH and LH levels were also measured in 4 patients with Turner's syndrome. Both levels were elevated and there observed no clear pulsatile secretion of FSH, but, some pulsatile secretion of LH was observed in two patients. These data indicate that patients with Turner's syndrome have decreased endogenous GH secretion, even though they show normal GH responses to GH provocative tests.

The scarcity of somatomedin/insulin-like growth factor (SM/IGF) has prevented investigation of the mechanism of SM/IGF action. Recently insulin-like growth factor I (IGF-I) has been synthesized by recombinant DNA technology. With the availability of large quantities of the biosynthetic IGF-I, we undertook a study of biological effects of IGF-I in vivo in rats. 120μg/day of IGF-I was administered continuously for 7 days via subcutaneous implanted osmotic minipump to hypophysectomized (hypox), normal, and diabetic rats. The body weights and tibial epiphyseal widths after 7 day treatment of IGF-I in both hypox and normal rats were significantly greater than those for untreated rats. Blood urea nitrogen levels in both hypox and normal rats treated with IGF-I were significantly lower than those for untreated rats, suggesting that IGF-I has anabolic action in vivo. In contrast to hypox and normal rats, in diabetic rats, IGF-I treatment did not stimulate growth in vivo, but, had a little anabolic and insulin-like effects in vivo.This study demonstrates that IGF-I has growth promoting, anabolic and insulin-like effects in vivo and suggests that IGF-I might be useful in the treatment of growth retardation but not that for diabetes mellitus.

The effect of a long-acting somatostatin analogue SMS 201-995 on GH secretion was investigated. Eleven acromegalic patients received a single dose of 50 micrograms SMS 201-995 administered subcutaneously, and plasma GH, IGF-I, GRF, TSH, IRI and blood glucose were determined at regular intervals. Nine of 11 patients had elevated basal plasma GH levels above 5 ng/ml. In all patients, plasma GH levels fell immediately from 39.5 +/- 17.3 ng/ml (mean +/- SEM) to 4.3 +/- 1.6 ng/ml (P less than 0.05) with a maximal inhibition of 82.9 +/- 3.3% of the basal levels and the suppression persisted for about 6 h of the observation period. IGF-I and GRF levels were not apparently altered. TSH and IRI levels also rapidly fell. Blood glucose levels fell slightly by 0.5 h. Ten of 11 patients had pain at injection sites. Except for this, no side effects were observed. Our results show that the new somatostatin analogue SMS 201-995 may inhibit GH hypersecretion in acromegalic patients for significant periods, suggesting that this agent can be a useful clinical tool for the treatment of acromegaly.

Serum somatomedin A was determined by a radioreceptor assay in six patients with GH deficiency before and after im administration of GH in doses between 0.5 and 8mg. The mean basal value of somatomedin A, 0.36±0.02 U/ml (mean±SEM), was significantly lower than that of age-matched controls, 0.82±0.02 U/ml. There was no diurnal variation. Somatomedin A levels increased significantly eight hours after GH administration, remained elevated for 48 hours and returned to basal levels after 72 hours. The mean levels of somatomedin A found 24 hours after 1, 2, 4 and 8 mg of GH were 0.45±0.05, 0.68±0.10, 0.71±0.08 and 1.03±0.02 U/ml, respectively. A linear dose-response curve between the logarithmic dose of GH and the somatomedin A increase was found in three of six patients.

The pituitary growth hormone (GH) responses during a 20-hour iv infusion of saline or human GH-releasing factor (hGRF-44) at 40 micrograms/h, followed by an iv bolus injection of hGRF at 2 micrograms/kg body weight, were studied in four normal adult men. During saline infusion only one or two pulses of plasma GH were observed. However, during hGRF infusion up to eight or ten pulses of GH were measured with an amplitude not different from that obtained during saline infusion. The mean +/- SEM integrated amount of GH secreted was 107 +/- 38.2 ng/ml.h in response to hGRF infusion, which was greater than the value of 25.4 +/- 3.5 ng/ml.h obtained during saline infusion. Plasma somatomedin-C also increased after hGRF infusion, but not after saline. After saline or hGRF infusion most of the subjects still responded to an iv bolus injection of the peptide (2 micrograms/kg). These results indicate that hGRF infusion augments GH secretion by increasing the number, but not the amplitude of GH pulses and that the infusion does not cause the pituitary somatotrophs to lose their capacity and ability to respond to hGRF subsequently.

We have investigated the effects of hormones and serum on glycosaminoglycan (GAG) synthesis, using cultured rat chondrocytes isolated from growing cartilage. Somatomedin A stimulated GAG synthesis at a physiological concentration, however in the case of insulin the dose required to stimulate GAG synthesis was 500 times as great as the physiological concentration. Parathyroid hormone also increased GAG synthesis. In contrast, hydrocortisone inhibited GAG synthesis at a pharmacological dosage. None of the following had any effect on GAG synthesis: epidermal growth factor, fibroblast growth factor, triiodothyronine, growth hormone, sex steroid or vitamin D3. Human serum up to a concentration of 1% stimulated GAG synthesis. Serum from patients with acromegaly stimulated GAG synthesis more than that from those with hypopituitarism.

Four patients with GH deficiency aged 6-14 years old were treated with hGRF for 6 months. Before the treatment maximal plasma GH responses to 50 micrograms iv hGRF administration were 48.6, 12.1, 24.3 and 13.0 ng/ml, respectively. Human GRF was administered at a dosage of 50-100 micrograms twice a day subcutaneously. In two patients, the growth rate was increased from 2.4 and 2.0 cm/year to 8.2 and 9.8 cm/year, respectively. In the other two patients, the growth rate did not change with hGRF treatment. Plasma somatomedin C levels increased in one patient but did not change in the other three. Antibody to hGRF was observed in two patients during the treatment, but the presence of antibody did not affect the growth rate.

125I-Labeled hGH was bound to liver plasma membranes which were obtained from female rats. The binding was displaced by hGH, hPRL, bPRL, rPRL and bGH but not by rGH. This result indicated that hGH was bound to lactogenic binding sites in rat livers. After hypophysectomy, the binding was markedly decreased. Treatment of hypophysectomized rats with hGH (80 micrograms/day) for 10 days increased the binding sites for hGH. These binding sites were different from those found in normal female rat livers because of their high affinity and specificity for hGH. These results indicate that hGH induces specific binding sites for hGH in rat livers.

The release of somatomedin from perfused livers of normal and hypophysectomized (hypox) rats has been studied. Somatomedin was determined by the radioreceptor assay for somatomedin A. The release of somatomedin in the perfusates of normal livers was observed during the initial 30 minutes and maintained during the second and third 30 minutes of recirculation. The addition of insulin at a concentration of 10 mU/ml to the perfusates caused a significant increase in the release of somatomedin in the 1st, 2nd and 3rd 30-minutes recirculatory perfusates. The addition of human growth hormone (25 micrograms/ml) and/or insulin (1 mU/ml) to the perfusates caused a significant increase in somatomedin after 120 minutes of recirculation. Hypox rats released amounts of somatomedin in perfusates similar to those of normal rats. The effect of insulin on the release of somatomedin was greater in hypox rats than that observed in normal rats. The molecular size of the somatomedin released in the perfusate was greater than that of purified somatomedin, suggesting that this somatomedin is bound to carrier proteins.

Plasma growth hormone (GH) responses to the repetitive administrations of synthetic human pancreatic growth hormone releasing factor (hpGRF-44) were studied in 15 patients with GH deficiency (11 diagnosed as idiopathic and 4 diagnosed as secondary to hypothalamo-pituitary tumor). hpGRF-44 was administered by single iv bolus (2 micrograms/kg), repetitive im (100 micrograms, twice a day), and/or repetitive iv infusion (2.5 micrograms/min for 90 min, once a day) for three to six consecutive days. Three of the eleven idiopathic GH deficient patients had plasma GH responses to both single iv bolus injection and repetitive administrations by im, or iv infusion of hpGRF. In four of the remaining eight, who had not had peak plasma GH levels above 5 ng/ml to a single iv bolus of the peptide, repetitive administrations of hpGRF-44 by im injection and/or iv infusion induced GH responses to the peptide. In the four patients with secondary GH deficiency, three had plasma GH response to hpGRF administration but one patient, who had indications of pituitary disorder, did not show any plasma GH response to either single iv injection or repetitive administrations of hpGRF-44. These data show that repetitive administrations of hpGRF-44 can induce plasma GH responses in some GH deficient patients who do not respond to a single iv bolus of the peptide.

Human growth hormone (hGH) in the pituitary extracts from patients with acromegaly and normal subjects was measured by radioimmunoassay (RIA) and radioreceptor assay (RRA) using pregnant rabbit liver membrane, and the RRA to RIA ratios of hGH were calculated. The RRA to RIA ratio of hGH for acromegaly was higher than that for normal (0.90 +/- 0.03 vs 0.75 +/- 0.03, p less than 0.01). When the pituitary extracts were gel filtered on Sephadex G-100 column there were three immunoreactive hGH peaks ("pre-big", "big", and "little" hGH); there were no significant differences in gel filtration patterns of hGH between acromegaly and normal. The "little" hGH component (major component) had a higher RRA to RIA ratio than "pre-big" hGH and "big" hGH in both acromegaly and normal. "Little" hGH extracted from acromegaly had a higher RRA to RIA ratio than that from normal (1.14 +/- 0.09 vs 0.93 +/- 0.04, p less than 0.05). These data support the hypothesis that hGH synthesized in acromegaly may be different from normal.

In a primary culture of bovine adrenal zona glomerulosa cells, insulin-like growth factor I (IGF-I)/somatomedin C stimulated DNA synthesis, as measured by [3H] thymidine uptake, at concentrations of 10(-9) and 10(-7) M. IGF-I also prevented ACTH-induced suppression of [3H] thymidine uptake. IGF-I in no way affected aldosterone secretion during short-term exposure to cultured cells, however. Our findings suggest that IGF-I plays an important role in the proliferation of adrenal zona glomerulosa cells.

Ten acromegalic patients were treated with the somatostatin analogue SMS 201-995 (SMS) for 3-38 weeks in various doses and by different administration routines (thrice daily or multiple sc injection). Plasma GH daily profiles, plasma IGF-I, urinary GH, serum TSH, IRI and fasting blood glucose (FBG) concentrations were measured before and during SMS treatment. Plasma GH rapidly decreased within one hour in all patients and was suppressed for at least 4 h after a 50 micrograms sc injection of SMS in 8 patients. Multiple injections of 300-600 micrograms/day SMS (25-50 micrograms X 12) suppressed GH throughout the day. Plasma IGF-I was completely normalized in 4 patients, and, in all but one of the others, decreased markedly. Urinary GH decreased within the first week of treatment in all patients and normalization was obtained in 3 patients. Shrinkage of the pituitary tumor, as determined by CT or MRI, was observed in 7 of 9 patients. Other clinical improvements, such as diminution or complete disappearance of swelling of soft tissues, excessive perspiration, and headache, were observed in 7 of 8 patients. Changes in serum TSH, IRI and FBG were seen in 3-4 patients, but without any apparent clinical problems. In conclusion, SMS is a useful clinical tool for treatment of acromegaly, and a multiple sc injection method seems to be preferable.

We produced antiserum to insulin-like growth factor I (IGF-I), and developed a specific and sensitive radioimmunoassay (RIA) for IGF-I using the biosynthetic IGF-I. This antiserum to IGF-I was specific for IGF-I; no cross-reactivities with multiplication stimulating activity, porcine insulin or human growth hormone (hGH) were detected. The sensitivity was 10-25 pg/tube with 50% displacement at 125 pg/tube. The intra- and inter-assay coefficients of variation for IGF-I were 5.4 and 9.7%, respectively. The plasma IGF-I levels as determined by RIA in normal adults (N = 46), patients with active acromegaly (N = 31), and pituitary dwarfs (N = 31) were 21.6 +/- 1.0, 157.3 +/- 17.0, and 2.5 +/- 0.3 ng/ml (Mean +/- SEM), respectively, indicating the levels were GH-dependent. The plasma IGF-I levels were significantly increased from 2.2 +/- 0.2 to 26.5 +/- 3.2 ng/ml after hGH administrations for three consecutive days in five pituitary dwarfs. The IGF-I levels were low in patients with hypothyroidism and liver cirrhosis, but were normal in patients with chronic renal failure. These data confirm previous reports and this radioimmunoassay proves useful in evaluating plasma IGF-I levels.

Specific insulin-like growth factor I (IGF-I) receptors on the Madin-Darby canine kidney (MDCK) cell line were identified and characterized. [125I]IGF-I specifically bound to the cells, but [125I]insulin bindings to the cells was minimal. Unlabeled IGF-I displaced both the IGF-I and insulin bindings with potencies that were 100 and 10 times as great as insulin. By an affinity labeling technique, IGF type I receptors were present in the MDCK cells. IGF-I stimulated DNA synthesis and cell proliferation at physiological concentrations. On the other hand, insulin had a little effect on DNA synthesis. These data suggest that IGF type I receptors as demonstrated in MDCK cells are involved in DNA synthesis and cell proliferation.

Synthetic human pancreatic GRF (hpGRF-44) was administered as an iv bolus to 139 normal children of short stature and 63 patients with GH deficiency. After a dose of 1 and 2 μg hpGRF-44/kg BW, mean plasma GH levels peaked at 15 and 30 min, respectively, with corresponding values of 32.2 ± 3.6 and 31.8 ± 2.4 (± SE) ng/ml in normal but short children. There were no differences according to sex or age in plasma GH response to hpGRF-44 between the ages of 4 and 18 years. A similar plasma GH response was observed when 2 μg hpGRF-44/kg BW was administered two hours after lunch. The overall plasma GH response was greater than that of insulininduced hypoglycemia and was similar to that obtained in the glucagonpropranolol test.Thirty-five of 63 patients with GH deficiency did not respond to a 2 μg hpGRF-44/kg BW. However, plasma GH increases to greater than 5 ng/ml occurred in the remaining 28 patients. Their mean GH level reached a peak at 90 min with a value of 8.8 ± 0.8 ng/ml. The peak values ranged between 5.1 and 17.8 ng/ml with a mean of 9.5 ± 0.8 ng/ml.These results suggest that hpGRF-44 is useful for evaluating pituitary Gil reserve in children of short stature and that some patients with GH deficiency, diagnosed on the basis of established tests, have Gil responses to hpGRF-44.

The effect of thyroid hormone on the serum level of somatomedin A was studied using a radioreceptor assay for somatomedin A. In 13 patients with hyperthyroidism, the mean level of somatomedin A was 0.06 +/- 0.05 U/ml, which was within the normal range. Low levels were found in 19 patients with primary hypothyroidism with a mean of 0.39 +/- 0.04 U/ml. After treating these patients with thyroxine, the serum somatomedin A levels returned to the normal range. There was a significant correlation between the somatomedin A level on one hand and T3 (r = 0.49) and T4 (r = 0.55) level on the other. The serum level of somatomedin A did not decrease for 7 days after thyroidectomy nor increase after treating hypophysectomized rats with 2 microgram of thyroxine for 14 days. However, the effect of growth hormone on serum somatomedin A was augmented 42.2% by the combined administration of the same amount of T4 for 7 days. There was a positive correlation between the serum level of somatomedin A and the percentage increase in body weight (4 = 0.73). These data suggest that thyroxine potentiates the effect of GH on synthesis and/or the secretion of somatomedin A.

Specific insulin-like growth factor I (IGF-I) receptors on a human erythroleukemia cell line (K-562 cells) were identified and characterized. [125I]-IGF-I specifically bound to K-562 cells and the binding was displaced by unlabeled IGF-I in a dose dependent manner, and half maximal inhibition of the binding was observed at 7 ng/ml IGF-I. [125I]IGF-I binding to the cells was displaced by multiplication stimulating activity (MSA) and by porcine insulin, with potencies that were 10, and 100 times less than that of IGF-I, respectively. By an affinity labeling technique, IGF type I receptors were found to be present in the K-562 cells. When the cells were differentiated by hemin (40 microM), specific binding of [125I]IGF-I to the cells was decreased to 56.8 +/- 5.0% of that for undifferentiated cells. Furthermore, at physiological concentration of IGF-I stimulated thymidine incorporation into DNA and increased the number of cells. These data demonstrate that K-562 cells have specific receptors for IGF-I which may be functionally important for these cells, and that the IGF-I binding sites decrease with cell differentiation. This system might be useful in studying the interaction of IGF-I receptors.

The concentration of somatomedin A (SMA) in various rat tissues was determined directly by the radioreceptor assay in supernates of tissue homogenates at 100,000 x g for 60 min. The SMA concentrations in pancreas, kidney, lung, liver, spleen, testis, brain and muscle were 2.56, 2.40, 2.28, 2.16, 1.56, 1.44, 0.60 and 0.30 U/g of wet tissue, respectively. The SMA content in rat serum was 6.66 U/ml. The SMA concentration in tissues never exceeded that in serum. When the 100,000 x g pellet of liver was treated with a hypotonic solution, the SMA content in the hypotonic solution was about 35% of that in the initial supernate. This result indicates that about 30% of the SMA in liver was stored in organellae. SMA in tissues decreased with incubation at 37 degrees C, though SMA in serum did not. This decrease could be precluded by adding 0.75 mM HgCl2 to the liver homogenate. The SMA content of the liver homogenate was dependent on growth hormone in experiments both in vivo and in vitro.