[Extrapancreatic hypoglycemic tumors. Apropos of a case of pleural fibrosarcoma]. / Tumeurs hypoglycémiantes extra-pancréatiques. Etude à propos d'un cas de fibrosarcome pleural.

The authors report a case of pleural fibrosarcoma associated with severe hypoglycaemia. Chromatography of the patient's serum and tumour fragments revealed a substance with a high molecular weight and an insulin-like activity. Professor Poffengarger's laboratory identified this substance as Non Suppressible Insulin-Like Protein or NSILAp which induces insulin-like effects on various tissues. A review of the literature is presented in the light of this case.

Insulina em invertebrados / Insulin in invertebrates

Este artigo reúne referências ao estudo de insulina e de substância insulina-símile em invertebrados publicadas na última década, constituindo-se numa revisäo de interesse para os que se dedicam ao ensino e à pesquisa na área de ciências biológicas. Analisa as metodologias utilizadas pelos diversos autores, os achados em protistas, procariotos e eucariotos e os conceitos admitidos em relaçäo à funcionalidade das estruturas estudadas

Growth hormone, somatomedin C, and nonsuppressible insulin-like activity levels compared in premature, small, average birth weight, and large infants.

We have investigated the relationship between growth hormone, somatomedin C, nonsuppressible insulin-like activity, weight, gestational age, and 1-minute Apgar score in newborn infants. The 153 infants were categorized as small for gestational age (n = 19), average for gestational age (n = 59), large for gestational age (n = 60), and premature (gestational age at birth, 36 weeks or less (n = 15). Our study showed that (1) growth hormone levels were elevated in premature infants and correlated with Apgar scores and birth weights; (2) somatomedin C and nonsuppressible insulin-like activity levels were significantly lower in premature than in term infants; and (3) the birth weight of all infants studied had a significant overall effect on both somatomedin C and nonsuppressible insulin-like activity levels, suggesting that these factors may be involved in fetal growth. However, because in small for gestational age infants somatomedin C and nonsuppressible insulin-like activity were similar to levels in average for gestational age infants, it is suggested that other factors may inhibit fetal growth.

Nonsuppressible insulin-like activity and somatomedin C levels in normal pregnant women, in pregnant women with gestational diabetes, and in umbilical cord blood of mature and premature infants.

This study was undertaken to determine the significance of the changes in nonsuppressible insulin-like activity as measured by the fat pad assay and by the levels of immunoreactive somatomedin C, growth hormone, and human placental lactogen in sera of term normal pregnant women, mothers who delivered prematurely, and women with gestational diabetes at term as compared to normal nonpregnant subjects. These hormones were also measured in the umbilical cord blood of these patients at the time of delivery to determine the possible mechanisms of the fetal growth in utero. Our investigations showed that (1) nonsuppressible insulin-like activity is elevated during pregnancy, but its level was lower in mothers with gestational diabetes in spite of significantly higher serum human placental lactogen compared with normal pregnant mothers; (2) nonsuppressible insulin-like activity is significantly lower in premature infants than in term infants; (3) somatomedin C levels were significantly elevated in pregnant mothers in spite of suppression of growth hormone; (4) nonsuppressible insulin-like activity and somatomedin C levels in infants of mothers with gestational diabetes were not significantly elevated in spite of higher birth weight, indicating that nonsuppressible insulin-like activity and somatomedins are not the only factors responsible for the increase of birth weight of children of diabetic mothers; (5) there was marked discordance between the growth hormone level in the neonates and somatomedin C levels.

Partial purification and characterization of somatomedin from sheep serum.

A rapid, high yield preparative technique for the isolation of sheep somatomedin is reported. Purification of biologically active somatomedin from the 60% ammonium sulfate precipitate of sheep serum was accomplished using three gentle fractionation steps. Biological activity during purification was monitored using the rat adipocyte nonsuppressible insulin-like activity (NSILA) assay. A stepwise pH elution (pH 2.85, 3.5, 4.5, and 6.0) from SP-Sephadex resulted in the elimination of more than 99% of the serum proteins and a 500-fold enhancement of biological activity. The active fraction eluted at pH 6.0 and was further fractionated on Sephadex G-50 (fine) chromatography at pH 2.85. This resulted in about a 10,000-fold enhancement of activity over serum activity. The most active fractions from Sephadex chromatography were further separated on reverse phase HPLC in 0.1% trifluoroacetic acid using a linear gradient of 24-60% acetonitrile. The biological activity of the final preparation was enhanced 61,000- to 182,000-fold over that of serum (mean, 93,000-fold) when assayed in the NSILA assay. Protein yield was estimated to be 467 micrograms/liter serum. In addition to the NSILA activity, the final preparation demonstrated dose-dependent sulfation factor activity in the embryonic chick pelvic leaflet bioassay. Sheep somatomedin was active at physiological levels in both bioassays. Analysis of the somatomedin preparation by sodium dodecyl sulfate-electrophoresis at pH 8.8 showed that it was homogeneous by this criterion. The activity eluted from Sephadex G-50 was estimated to have a molecular size of 6900. Two Coomassie blue-stained bands were present in the final sheep somatomedin preparation after polyacrylamide gel electrophoresis at pH 3.2. Our purification process is a rapid, high yield technique which yields a polypeptide fraction enriched in NSILA and somatomedin-like activity. The molecular size and biological activity in the NSILA and sulfation factor assays suggest that our sheep NSILA is analogous to somatomedins purified from other species of animals.

[Serum levels of receptor assayable insulin-like activity in various diseases].

Utilizing an acid gel chromatography and insulin radioreceptor assay (RRA), serum levels of receptor assayable insulin-like activities were measured under various conditions. Acid gel filtration of sera on a Sephadex G-50 was adopted to separate small molecular ILAs from binding proteins before the assay by RRA. By employing 125I-pork insulin as the tracer, and pork insulin as the standard, an RRA for insulin was developed, in which kidneys of sacrificed pregnant guinea pigs were used as the source of the solubilized receptor. After gel-filtration of the sera, pooled fractions, which grossly corresponded to those of 125I-insulin marker, were assayed by RRA. The subjects consisted of fifty-nine cases: normal control subjects (n = 19), active acromegaly (6), Sheehan's syndrome (5), liver cirrhosis (7), chronic renal failure (10), non-insulin dependent diabetes mellitus (6), overt hyperthyroidism (5) and Nelson's syndrome (1). The average receptor assayable ILA of the normal control subjects was 40.2 +/- 12.2 ng/ml. As insulin RRA has a big interassay variation, receptor assayable ILA-ratio was used to minimize the variation, and each data was shown as the ratio to the average ILA of the normal controls. By this method, sera from normal adults had a mean (+/- SD) receptor assayable ILA ratio of 1.00 +/- 0.28. Four out of six cases of acromegaly revealed significantly high concentrations, and the average receptor assayable ILA-ratio of acromegaly was 1.30 +/- 0.28 (mean +/- SD, p less than 0.015). In the cases of Sheehan's syndrome, the ILA-ratio was 0.30 +/- 0.12, which was significantly low (p less than 0.001). Therefore, GH dependency was suspected from these two factors. However, the direct correlation was not indicated between GH and receptor assayable ILA. It was also considered that receptor assayable ILA was influenced not only by GH but also by some other factors. Furthermore, the subjects with liver cirrhosis indicated the low levels of receptor assayable ILA-ratio of 0.46 +/- 0.31, while the subjects with chronic renal failure showed the high ILA-ratio of 1.59 +/- 0.45 (p less than 0.05). No differences in ILA-ratio were found in the subjects with diabetes mellitus, hyperthyroidism and Nelson's syndrome, compared to the normal subjects.

Nonsuppressible insulinlike activity (NSILA) and the glucose dyshomeostasis of agonal sepsis.

Peritonitis was induced through the ligation and puncture of rat ceca. The rats were divided into three groups: 1) rats whose ceca were ligated and punctured (CLP); 2) rats whose ceca were isolated and replaced without being tied or perforated (SHAM); and 3) rats which were fasted but not subjected to surgery (FC). Plasma glucose levels, serum insulin content, basal and stimulated glucose oxidation rates of adipose tissue, and nonsuppressible insulinlike activity were measured at the time of death or sacrifice. CLP rats were hypoglycemic (35.9 +/- 2.7 mg/dl) at death whereas both FC and SHAM groups were normoglycemic at 101 +/- 1.6 mg/dl and 94.3 +/- 3.9 mg/dl, respectively. Terminal serum immunoreactive insulin content for the three groups did not vary from each other. The oxidation of 14C-glucose to 14CO2 by the septic rats' epididymal fat pads was significantly greater than either SHAM or FC (56.3 +/- 6.4 vs 35.0 +/- 3.3 or 24.5 +/- 2.4 X 10(3) 14CO2 dpm/g/h). When a suprastimulatory concentration of insulin (1 mU/ml) was added in vitro, the septic rats' fat pads were further stimulated to a greater glucose oxidation rate than either SHAM or FC group. Finally, nonsuppressible insulinlike activity (NSILA) was assessed by the addition of guinea pig antiinsulin serum (GPAIS) and rat sera to the in vitro preparations. CLP sera demonstrated a significantly greater NSILA level than either control group. The gathered data suggest that enhanced peripheral tissue glucose oxidation in late sepsis is associated with elevated NSILA.

Deficiency of non-suppressible insulin-like activity in thalassaemia major.

The commonly occurring short stature in the condition of thalassaemia major was investigated with respect to the possible role of the somatomedin growth factor low molecular weight non-suppressible insulin-like activity (NSILAs). Nineteen affected patients (12 boys, 7 girls) aged between 2 and 21 years were studied. Twelve of them were on or below the 10th centile for height of whom 7 were on or below the 3rd centile for height. Serum immunoreactive growth hormone responses to exercise were normal in 9 of 11 subjects tested. Using an isolated fat cell bioassay NSILAs was undetectable in 10 and was more than 2 SD below the normal mean value in the other 9 subjects. High molecular weight NSILA (not a growth factor) was very low or undetectable in all 9 subjects tested. Low molecular weight NSILAs did not show the normal correlation with age in childhood, nor was there any correlation with height, height velocity, or bone age. The 2 children above the 50th centile for height had undetectable NSILAs. There was no evidence of iron or ferritin interfering in the bioassay, and mixing experiments showed no evidence of inhibitory activity towards NSILAs in thalassaemic sera. Low circulating levels of the somatomedin NSILAs may contribute to the short stature in thalassaemia major, but other factors may permit normal growth in some affected children.

[Mesenchymatous tumour of the thigh causing hypoglycaemia with circulating protein of high insulin activity (author's transl)]. / Tumeur mésenchymateuse hypoglycémiante de la cuisse. Presence d'une protéine circulante d'activité insulinique élevée.

An 87-year-old woman underwent surgery for a dermato-fibrosarcoma of the thigh, responsible for hypoglycaemic episodes. There was a high level of NSILP contrasting with a low level of NSILAs. This is the second case where such a finding has been made in a patient suffering from an extra-pancreatic tumour causing hypoglycaemia. The possible aetiological role of NSILP in extra-pancreatic tumours causing hypoglycaemia is discussed.

[Mesenchymal tumor associated with hypoglycemia and an elevated NSILP (author's transl)]. / Tumeur mésenchymateuse hypoglycémiante de la cuisse avec NSILP élevé.

An unusually located mesenchymal tumor with hypoglycemia is observed. Insulin, cortisol, growth hormone, glucagon levels are within the normals. The glucogenic aminoacids have also been measured, as well as the NSILP which was three times as high as the upper limit of normal values. The various processes which might have brought about the patient's hypoglycemia are discussed.

[Contribution of the IGF (insulin-like growth factors or somatomedins) competitive binding assay in the study of growth disorders in children (results for 124 observations) (author's transl)]. / Apport du dosage par compétition des IGF (insulin-like growth factors ou somatomédines) dans l'étude des troubles de croissance de l'enfant. Résultats de 124 observations.

A competitive binding assay for IGF (insulin-like growth factors) employing a specific carrier protein produced by rat liver in culture has been used in a study of a variety of growth disorders in children. In 34 subjects with a total somatotropic deficiency, serum IGF levels were significantly (p < 0.001) lower than those in normal children for whom the means were 0.57 +/- 0.05 (SEM) U/ml between the ages of 1 and 5, and 1.01 +/- 0.11 U/ml between the ages of 5 and 15. Within this group of patients, there was also a significant difference in IGF levels depending on whether the deficiency was idiopathic (0.16 +/- 0.03 U/ml) or caused by a tumour (0.49 +/- 0.06 U/ml). IGF levels were particularly low in 2 cases of Laron's syndrome (0.08 and 0.03 U/ml) and 6 cases of coeliac disease (0.19-0.27 U/ml). In the later group, a gluten-free diet resulted in a rise in IGF levels. However, the stunted growth observed in 10 cases of Cushing's syndrome was found to be independent of IGF levels which fell within the normal range (1.02 +/- 0.11 U/ml). For 34 children investigated because of idiopathic retarded growth varying from --2 to --4 SD, the mean IGF levels (0.68 +/- 0.04 U/ml) were significantly lower than controls (p < 0.001). By contrast, abnormally high IGF levels were found in children with tall stature (> 3 SD). In 7 children aged between 1 and 5, the mean was 0.94 +/- 0.05 U/ml and in 17 older patients, 1.47 +/- 0.11 U/ml, with some cases reaching levels similar to those of untreated acromegalics. In both age groups the means were significantly higher than control levels (p < 0.001). Oestrogen treatment led to a progressive drop in IGF levels accompanied by slower growth, and normal levels were reached by the time ossification was established.

Serum levels of the acid-ethanol soluble component of non-suppressible insulin-like activity in untreated and treated streptozotocin-diabetic rats.

Streptozotocin-diabetic rats suffered growth failure and had reduced serum levels of the acid--ethanol soluble component of non-suppressible insulin-like activity (NSILA-S) compared with normal rats. Chronic insulin substitution (6 weeks) resulted in a normalization of serum levels of NSILA-S; this was accompanied by a normal increase in weight. Insulin therapy for 3 days resulted in a partial recovery of serum levels of NSILA-S and a slight but significant accompanying gain in weight. Short-term administration of GH also resulted in a partial recovery of the serum level of NSILA-S, in spite of continued uncontrolled diabetes. These results demonstrate that, in the rat, insulin as well as GH contributes to the regulation of serum levels of NSILA-S.

Determination of nonsuppressible insulin-like activity in human serum by a sensitive protein-binding assay.

We describe a sensitive protein-binding assay for non-suppressible insulin-like activity in human serum. It can detect as little as 0.2 microunits (corresponding to 0.5 ng) of the activity in 0.4 ml of the assay mixture. It is measured in a low-molecular-weight fraction (termed "biological material") obtained by chromatography of serum on Sephadex G-50 in 1 mol/liter acetic acid. This fraction has been shown earlier to contain nearly all this billogically active material that is present in serum. A partially purified carrier protein from human serum is used as the binding protein; different concentrations of a partially purified preparation of material with the activity serve as standards, which compete with 125l-labeled tracer for binding. Biological material dilutes more or less in parallel with the standard over a 10-fold concentration range. In the chromatographed serum fractions, displacing activity appears between 50 and 80% bed volume, with the peak at 60%, and coincides with the distribution and the peak of radioactivity obtained by chromatography of tracer. A good correlation (r = 0.88) is observed between the values determined for this activity in the rat fat-pad assay and the protein-binding assay, although the latter yields about two fold higher results (190 +/- 37 milliunits/liter vs. 345+- 65 milliunits/liter, mean values for 18 normal sera). Values determined in the protein-binding assay are decreased in hypopituitary patients (183 +/- 27 milliunits/liter) and increased in acromegalics (486 +/- 88 milliunits/liter), in accord with the results of the bioassay (68 +/- 21 milliunits/liter for hypopituitary patients, 293 +/- 53 for acromegalics).