Insulin-like Activity In Serum Research Articles

Inhibition of tumor size by streptozotocin-induced diabetes mellitus

The effects of experimental diabetes mellitus on tumor growth were studied. Male Fischer rats were rendered diabetic with a single intravenous injection of streptozotocin. Ten days later they were inoculated with 10 6 cells of a methylcholanthrene-induced sarcoma, and tumor growth was observed for 28 days. In three consecutive experiments diabetes selectively inhibited tumor size at Day 28 following inoculation, by 65% ( n = 24, P < 0.05), 63% ( n = 30, P < 0.001), and 81% ( n = 54, P < 0.001) compared to nondiabetic controls. Tumors became palpable in diabetic animals later than in control animals, but palpable tumors grew at a similar rate in the two groups. In diabetic animals with tumors, fasting blood glucose was inversely related to tumor size ( r = −0.80, P < 0.001). This decrease in blood glucose in diabetic animals with large tumors could not be explained by increased insulin or insulin-like activity in serum or tumor extracts. Insulin binding studies to isolated tumor cells showed that tumor cells from diabetic animals had increased numbers of lower-affinity insulin receptors compared to tumor cells from nondiabetic animals. These findings suggest that insulin deficiency or an associated factor in diabetes mellitus causes a marked delay in tumor appearance.

The nature of human serum insulin-like activity (ILA)P Characterization of ILA in serum and serum fractions obtained by acid-ethanol extraction and adsorption chromatography.

Studies were undertaken in an attempt to clarify the apparent heterogeneous nature of human serum insulin-like activity. Methods of preparative zone electrophoresis on Pevikon, acid-ethanol extraction of trichloroacetic acid serum protein precipitates, adsorption chromatography on DEAE-cellulose and Dowex 50, gel filtration chromatography, and insulin antiserum immunoreactivity were used. The results establish the presence of a substance in serum with in vitro biological properties similar to insuln but with different physicochemical properties. The major portion of serum ILA measured by bioassay techniques can be attributed to the effects of this substance. Whereas the in vitro biological effects of this substance on muscle and adipose cells were similar to those of crystalline insulin, the substance is distinguished from insulin by: (1) the failure of insulin antiserum to inhibit its in vitro biological effect; (2) a slower electrophoretic mobility (in the gamma-beta globulin zone); and (3) a larger molecular weight, between 40,000 and 50,000 in these studies. It is similar to insulin since both are soluble in acid-ethanol. The results further indicate that previously described insulin-like activity in gamma-beta globulin preparations, the major portion of total serum insulin activity described in acid-ethanol extracts of serum, "bound" insulin, "atypical" insulin, and antibody nonsuppressible insulin-like activity bioassayed in diluted serum are all one and the same substance.

Quantitation and partial characterization of nonsuppressible insulin-like activity in serum and tissue extracts of the rat.

Nonsuppressible insulin-like activity (NSILA), as measured in the presence of insulin specific antiserum (GPAS) in the isolated fat cell and rat hemidiaphragm bio-assays, was demonstrated in the serum and in acid-ethanol extracts of tissues of the male Wistar rat. By this technique, no clear single organ site of synthesis or storage of this material was discerned. When rat serum was chromatographed on Dowex 50 × 8 resin and subjected to zone electrophoresis on a Pevikon block, its behavior was identical with that of human serum. Further studies were carried out on a single selected tissue extract, liver, employing: Pevikon electrophoresis, Sephadex G-100 gel filtration, biologic activity on muscle and adipose tissue, heating and thiol inactivation. By these criteria, NSILA, extracted from rat liver, has a molecular weight approximating 50,000, migrates in the gamma and beta globulin region on electrophoresis and in all other ways tested is quite analogous in its behavior to human serum NSILA. Isolated rat...

Non-suppressible insulin-like activity of human serum I. Physicochemical properties, extraction and partial purification

1. 1. Human serum insulin-like activity (ILA) measured by the rat adipose tissue assay is only partially neutralized by anti-insulin serum. Since the portionot suppressed by anti-insulin serum (non-suppressible ILA) represents the major part of serum ILA, it seemed of importance to investigate its physiochemical properties, 2. 2. The molecular weight of non-suppressible ILA in serum as estimated by gel filtration was between 70 000 and 150 000. On paper electrophoresis it migrated with the α 2- and β-globulins. 3. 3. A purified material containing 1775 μU non-suppressible ILA per mg was obtained from human plasma by a modified Cohn fractionation procedure followed by extraction in acidic ethanol and by gel filtration. 4. 4. Paper electrophoresis separated the purified material into two components, a basic protein devoid of non-suppressible ILA and a β-globulin containing all the non-suppressible ILA. 5. 5. No insulin A-chain was found in purified non-suppressible ILA by paper electrophoresis in 20% formic acid. 6. 6. Purified non-suppressible ILA was heat stable (80°). It was inactivated by alkali and by reduced glutathione. 7. 7. Gel filtration revealed that at neutral pH non-suppressible ILA formed aggregates of different size, which in 5M acetic acid dissociated into one uniform species of molecules with a molecular weight between 6000 and 10 000. 8. 8. The identity of the purified non-suppressible ILA with that present in native serum has not yet been proved.

Non-suppressible insulin-like activity of human serum: II. Biological properties of plasma extracts with non-suppressible insulin-like activity

1. 1. Extracts of human plasma globulins with 52 (extract B) to 1775 (purified extract B) μU non-suppressible insulin-like activity (ILA) per mg protein were tested with regard to their biological properties in several insulin-assay procedures in vitro and in vivo. 2. 2. The effects of purified extract B on glucose metabolism of rat and human adipose tissue and on isolated fat cells in vitro were the same as those of crystalline insulin. Extract B stimulated the transport of glucose from the extracellular into the intracellular space of rat adipose tissue. Glycerol release of adipose tissue of fasted-refed rats was inhibited by extract B as well as by crystalline insulin in the absence of glucose in the medium. 3. 3. Incorporation of uniformly labelled [ 14C]glucose into glycogen of mouse diaphragm in vitro was stimulated by extract B as well as by crystalline insulin. 4. 4. When injected intraperitoneally into mice, extract B enhanced [ 14C]glucose incorporation into muscle glycogen and adipose tissue lipids. 5. 5. Purified extract B administered intravenously to rats lowered their serum glucose, decreased the biological half-life of serum glucose from a basal level of 18 to 9 min and enhanced the incorporation of [6- 14C]glucose into the glycogen of the diaphragm and into the total lipids of adipose tissue. Compared with crystalline insulin, the effects of purified extract B on the diaphragm clearly surpassed those on adipose tissue. 6. 6. Whereas the effects of crystalline insulin were inhibited by the simulataneous injection of anti-insulin serum, those of purified extract B were not. 7. 7. The increase of glucose assimilation brought about by these small doses of insulin and purified extract B subsided 15 min after injection, whereas the effects on the tissues remained more or less constant up to 30 min. 8. 8. The apparent inefficacy of unaltered non-suppressible ILA in human serum in vivo contrasts with its effectiveness in vitro and with the effects of extracted non-suppressible ILA in vivo. These phenomena are discussed with regard to a possible physiological role of non-suppressible ILA.

Insulin and insulin-like activity in serum and extravascular fluid

In fasted, fed or i. v. glucose injected rats, the close approximation between immuno-reactive insulin (IRI) and insulin-like activity (ILA) in the abdominal lymph, contrasts with the high discrepancy between IRI and ILA in the corresponding serum. Implications of the physiological role of IRI and ILA are discussed.

INSULIN-LIKE ACTIVITY IN SERUM OF NORMAL AND DIABETIC SUBJECTS. RESULTS OBTAINED WITH DUAL ASSAY MEASURING CONVERSION OF C-14 GLUCOSE TO CO2 AND TO LIPID IN RAT ADIPOSE TISSUE.

Epididymal fat pad assays of insulin-like activity in plasma of normal and diabetic subjects have been carried out. When conversion of l-C-14 glucose to C-14-O2 was used as a measure of ILA, diabetics revealed elevated fasting levels, and adult diabetics showed an exaggerated ILA response to glucose loads. Juvenile-type diabetics had lower levels of ILA than the adult diabetics and responded less well to glucose. When the measure was the conversion of 6-C-14 glucose to lipid, no elevation in fasting ILA was found in diabetics. Evidence was obtained indicating that elevated levels of NEFA may inhibit the effect of insulin on adipose tissue with respect to fat synthesis from glucose and not CO2 production. Possible explanations for the discrepancy in the two ILA parameters are discussed.

The Insulin‐like Activity in Serum Determined by the Rat Epididymal Fat Method

Acta Medica ScandinavicaVolume 175, Issue 4 p. 401-408 The Insulin-like Activity in Serum Determined by the Rat Epididymal Fat Method V. The Distribution of Insulin-like Activity in Electrophoretically-separated Serum Protein Fractions from Normal Fasting Subjects and the Effect of Ingestion of Glucose JENS LYNGSØE, JENS LYNGSØE Second University Clinic of Internal Medicine (Head: K. Lundbæk, M. D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this author JENS LYNGSØE, JENS LYNGSØE Second University Clinic of Internal Medicine (Head: K. Lundbæk, M. D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this author First published: January/December 1964 https://doi.org/10.1111/j.0954-6820.1964.tb00589.xCitations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume175, Issue4January/December 1964Pages 401-408 RelatedInformation

Studies on the state of insulin in blood: materials and methods for the estimation of "free" and "bound" insulin-like activity in serum.

New techniques have been introduced by the authors and collaborators in the course of their studies on the state, transport and regulation of insulin in man. The discovery that a portion of insulin in blood circulates in a complex form extractable by cationic exchange resins (Nacycle) led to the development of a simple technique for the separation of this portion of insulin from whole serum. The observation that insulin in its complex form is devoid of insulin activity, when assayed in vitro under specified conditions, resulted in the finding that factors present in adipose tissue extracts could dissociate the blood insulin complex (es). Methods have been developed therefore for the extraction, storage, preservation and “standardization” of these factors from adipose tissue. Studies on the ratio of “free” and “bound” insulin-like activity in serum suggest that this ratio does not represent a purely physicochemical equilibrium between “bound” and “free” insulin. This ratio depends upon the metabolic state ...

IDIOPATHIC SPONTANEOUS HYPOGLYCEMIA IN CHILDREN

Seven cases of idiopathic spontaneous hypoglycemia in children are reported. A review is made of 51 case reports of this condition found in the literature. The onset of symptoms occurred under the age of 6 months in 60% of the cases and of these, over half showed permanent neurologic sequelae. Of 23 cases first developing symptoms when over 6 months of age only 3 later showed permanent brain damage. Of the total 58 cases, 90% first developed symptoms when under 2 years of age. Although an elevation of the blood sugar to normal levels is often seen during treatment with ACTH, some patients do not respond favorably to this treatment, nor to treatment with adrenocorticosteroids. Treatment by dietary means is of little value. Of the 58 cases, 25 underwent partial pancreatectomy; 15 were cured and 10 were not. It is the authors' belief that partial pancreatectomy should be performed in those cases which do not respond to medical treatment within 1 to 2 years. The pancreas was examined histologically in 29 cases and in 9 of these there was evidence of hypertrophy or hyperplasia of the islets of Langerhans. No familial incidence was noted with the exception of two reported series. Of the total 58 cases, 7 died; in 3, the death was a direct result of the hypoglycemia. The etiology is discussed. Although few cases have been studied, high levels of circulating insulin-like activity in serum have been previously recorded in two patients. A normal value in one patient is recorded here. Cases may be classified as leucine-sensitive and leucine-insensitive according to the blood sugar response to this amino acid. The possibility exists that another cause may be an inability to raise the blood glucose by the release of adrenalin. The "syndrome of idiopathic hypoglycemia of infants" as described by McQuarrie is believed by the authors not to be a single clinical entity.