ABSTRACT
We studied the ability of ATP to inhibit in vitro the degrading activity of insulin-degrading enzyme. The enzyme was purified from rat skeletal muscle by successive chromatographic steps. The last purification step showed two bands at 110 and 60 kDa in polyacrylamide gel. The enzyme was characterized by its insulin degradation activity, the substrate competition of unlabeled to labeled insulin, the profile of enzyme inhibitors, and the recognition by a specific antibody. One to 5 mM ATP induced a dose-dependent inhibition of insulin degradation (determined by trichloroacetic acid precipitation and insulin antibody binding). Inhibition by 3 mM adenosine 5'-diphosphate, adenosine 5'-monophosphate, guanosine 5'-triphosphate, pyrophosphate, beta-gamma-methyleneadenosine 5'-triphosphate, adenosine 5'-O-(3 thiotriphosphate), and dibutiryl cyclic adenosine 5'-monophosphate was 74%, 4%, 38%, 46%, 65%, 36%, and 0%, respectively, of that produced by 3 mM ATP. Kinetic analysis of ATP inhibition suggested an allosteric effect as the plot of 1/v (insulin degradation) versus ATP concentration was not linear and the Hill coefficient was more than 1 (1.51 and 2.44). The binding constant for allosteric inhibition was KiT = 1.5 x 10(-7) M showing a decrease of enzyme affinity induced by ATP. We conclude that ATP has an inhibitory effect on the insulin degradation activity of the enzyme.
Subject(s)
Adenosine Triphosphate/pharmacology , Insulin/metabolism , Insulysin/antagonists & inhibitors , Animals , Antibodies , Chromatography, Affinity , Electrophoresis, Polyacrylamide Gel , Enzyme Inhibitors/pharmacology , Enzyme Stability , Immunoblotting , Insulin/immunology , Insulysin/immunology , Insulysin/isolation & purification , Male , Muscle, Skeletal/enzymology , Rats , Rats, Wistar , Trichloroacetic AcidABSTRACT
Insulin degrading enzyme (IDE) is a metalloprotease that has been involved in amyloid beta peptide (A(beta)) degradation in the brain. We analyzed the ability of human brain soluble fraction to degrade A(beta) analogs 1-40, 1-42 and the Dutch variant 1-40Q at physiological concentrations (1 nM). The rate of synthetic 125I-A(beta) degradation was similar among the A(beta) analogs, as demonstrated by trichloroacetic acid precipitation and SDS-PAGE. A 110 kDa protein, corresponding to the molecular mass of IDE, was affinity labeled with either 125I-insulin, 125I-Abeta 1-40 or 125I-A(beta) 1-42 and both A(beta) degradation and cross-linking were specifically inhibited by an excess of each peptide. Sensitivity to inhibitors was consistent with the reported inhibitor profile of IDE. Taken together, these results suggested that the degradation of A(beta) analogs was due to IDE or a closely related protease. The apparent Km, as determined using partially purified IDE from rat liver, were 2.2 +/- 0.4, 2.0 +/- 0.1 and 2.3 +/- 0.3 microM for A(beta) 1-40, A(beta) 1-42 and A(beta) 1-40Q, respectively. Comparison of IDE activity from seven AD brain cytosolic fractions and six age-matched controls revealed a significant decrease in A(beta) degrading activity in the first group, supporting the hypothesis that a reduced IDE activity may contribute to A(beta) accumulation in the brain.
Subject(s)
Alzheimer Disease/enzymology , Amyloid beta-Peptides/metabolism , Brain/enzymology , Insulysin/metabolism , Peptide Fragments/metabolism , Animals , Blotting, Western , Case-Control Studies , Electrophoresis, Polyacrylamide Gel , Humans , Hydrolysis , Rats , Rats, Wistar , Substrate SpecificityABSTRACT
The study was done using 39 guinea pigs grouped as followed; 18 were injected with 0.5 mg of porcine insulin emulsified in complete Freund's adjuvant; 12 were injected with saline and 9 were used as control of cardiac bleeding during the assay. Intraperitoneal glucose tolerance tests (IGTT) were carried out on days 0, 11, 32 and 38. Seven of the thirteen guinea pigs immunized with insulin which survived after the study, showed glucose intolerance on day 32 at 90 and 120 min (p < 0.01 and p < 0.001) and on day 38 at 120 min (p < 0.05). Anti-idiotypic IgG partially purified from a sera pool from these animals inhibited 125-Insulin binding to rat hepatocytes, immunoprecipitated 125I-rat insulin receptors and recognized the alpha-subunit of insulin receptor in immunoblotting. We conclude that insulin anti-idiotypes in guinea pigs offer a simple way to produce antibodies against insulin receptor binding site. The methodology for anti-idiotype identification can be applied to patients with insulin resistance.
Subject(s)
Antibodies, Anti-Idiotypic/isolation & purification , Antibody Formation/immunology , Blood Glucose/immunology , Insulin/immunology , Animals , Glucose Tolerance Test , Guinea Pigs , Male , Rats , Rats, Wistar , Receptor, Insulin , Time FactorsABSTRACT
Twenty six children with hypoglycaemia were diagnosed and followed between 1975 and 1995. Diagnosis was confirmed by a high insulin:glucose ratio, and low free fatty acid and 3-hydroxybutyrate on fasting. All patients were treated with diazoxide at a maximum dose of 20 mg/kg/day. Requirement of a higher dose was considered as a failure of medical treatment and an indication for surgery. Sixteen children Responded to diazoxide; 10 failed to respond and underwent pancreatic resection. Six of the latter group started with symptoms in the neonatal period. Eleven of the 26 children have neurological sequelae. Head growth and neurological outcome correlated well. Additionally, non-specific electroencephalogram abnormalities (slow waves) appear to be indicative of subclinical hypoglycaemia during follow up.
Subject(s)
Hyperinsulinism/therapy , Hypoglycemia/therapy , Pancreatectomy , Diazoxide/therapeutic use , Electroencephalography , Female , Follow-Up Studies , Head/growth & development , Humans , Hyperinsulinism/diagnosis , Hyperinsulinism/physiopathology , Hypoglycemia/diagnosis , Hypoglycemia/physiopathology , Infant , Infant, Newborn , MaleABSTRACT
The study was done using 39 guinea pigs grouped as followed: 18 were with 0.5 mg of porcine insulin emulsified in complete Freund´s adjuvant; 12 were injected with saline and 9 were as control of cardiac bleeding during the assay. Intraperitoneal glucose tolerance tests (IGTT) were carried out on days 0, 11,32 and 38. Seven of the thirteen guinea pigs immunized with insulin which survived after the study, showed glucose intolerance on day 32 at 90 and 120 min (p<0.01 and p<0.001) and on day 38 at 120 min (p<0.05). Anti-idiotypic IgG partially purified from a sera pool from these animals inhibited (125-)Insulin binding to rat hepatocytes, immunoprecipitated (125)I-rat insulin receptors and recognized the alpha-subunit of insulin receptor in immunobloting. We conclude that insulin anti-idiotypes in guinea pigs offer a simple way to produce antibodies against insulin receptor binding site. The methodology for anti-idiotype identification can be applied to patients with insulin resistance.
Subject(s)
Male , Animals , Guinea Pigs , Rats , Antibodies, Anti-Idiotypic/isolation & purification , Antibody Formation/immunology , Blood Glucose/immunology , Insulin/immunology , Glucose Tolerance Test , Immunoblotting , Rats, Wistar , Receptor, Insulin , Time FactorsABSTRACT
The study was done using 39 guinea pigs grouped as followed: 18 were with 0.5 mg of porcine insulin emulsified in complete Freund s adjuvant; 12 were injected with saline and 9 were as control of cardiac bleeding during the assay. Intraperitoneal glucose tolerance tests (IGTT) were carried out on days 0, 11,32 and 38. Seven of the thirteen guinea pigs immunized with insulin which survived after the study, showed glucose intolerance on day 32 at 90 and 120 min (p<0.01 and p<0.001) and on day 38 at 120 min (p<0.05). Anti-idiotypic IgG partially purified from a sera pool from these animals inhibited (125-)Insulin binding to rat hepatocytes, immunoprecipitated (125)I-rat insulin receptors and recognized the alpha-subunit of insulin receptor in immunobloting. We conclude that insulin anti-idiotypes in guinea pigs offer a simple way to produce antibodies against insulin receptor binding site. The methodology for anti-idiotype identification can be applied to patients with insulin resistance. (AU)
Subject(s)
Male , Animals , Guinea Pigs , RESEARCH SUPPORT, NON-U.S. GOVT , Rats , Insulin/immunology , Blood Glucose/immunology , Antibodies, Anti-Idiotypic/isolation & purification , Antibody Formation/immunology , Time Factors , Receptor, Insulin , Rats, Wistar , Immunoblotting , Glucose Tolerance TestABSTRACT
The so-called Xp21 contiguous deletion syndrome or complex glycerol kinase deficiency (GKD) usually presents with classical Duchenne muscular dystrophy (DMD) or a milder dystrophic myopathy, adrenal hypoplasia, and GKD. A number of syndromic and nonsyndromic cases of agenesis of the corpus callosum (ACC) also map to that location. To date, none of the cases of complex GKD have been associated with ACC. Here, we report on a patient with a complex phenotype as a result of the Xp21 contiguous deletion syndrome in association with ACC. Biochemical, cytogenetic, and molecular analyses were performed to detect and establish the size of the genomic deletion. It is at least 3 million base pairs in length; however, exact limits could not be determined in the present study. Nevertheless, we suggest the presence of a primary gene involved in the embryogenesis of the corpus callosum between Xp21.1 and Xp22.11.
Subject(s)
Agenesis of Corpus Callosum , Gene Deletion , Glycerol Kinase/genetics , X Chromosome , Child , Humans , Infant, Newborn , Male , SyndromeABSTRACT
In the present study we describe a non-enzymatic technique for the isolation of rat hepatocytes by perfusion of liver through portal vein. The perfusion media consist of 1 mM sodium perchlorate, 5 mM sodium citrate, 10 mM glucose, 129 mM NaCl and 0.1% bovine-serum albumin at pH 7.4. After purification through diatrizoate gradient, electron microscopical studies revealed that most of purified hepatocytes were well preserved and presented a normal ultrastructure, thus correlating with previous biochemical results. The present method enables the recovery of metabolically and morphologically normal hepatocytes.
Subject(s)
Cell Separation/methods , Citrates , Liver/ultrastructure , Perchlorates , Sodium Compounds , Animals , Cell Survival , Centrifugation, Density Gradient , Diatrizoate , Male , Perfusion , Rats , Rats, Wistar , Sodium CitrateABSTRACT
A 33 year old woman with episodes of severe hypoglycemia is presented. The studies showed anti-insulin antibodies and variable C-peptide levels. Circulating insulin measured after acid-ethanol extraction, was of 1,600 uU/ml and shown to be human insulin after characterization by HLPC. Specific anti-human insulin antibodies were of high affinity (Ka1: 6.20 x 10(10) M-1; Ka2: 2.42 x 10(9) M-1). A small cross-reactive porcine and bovine antibody subpopulation was also detected (IgG, light k type chain). Plasmapheresis was undertaken when symptoms were spontaneously declining and turned antibody title negative. Prolonged follow-up showed no relapse of this syndrome.
Subject(s)
Autoimmune Diseases/immunology , Hypoglycemia/immunology , Insulin Antibodies , Adult , Autoimmune Diseases/therapy , Chromatography, Affinity , Cross Reactions , Female , Humans , Hypoglycemia/therapy , Insulin/blood , Plasmapheresis , SyndromeABSTRACT
In the present study we describe a non-enzymatic technique for the isolation of rat hepatocytes by perfusion of liver through portal vein. The perfusion media consist of 1 mM sodium percholorate. 5 mM sodium citrate, 10 mM glucose, 129 mM NaCl and 0.1 per cent bovine-serum albumin at pH 7.4. After purification through diatrizoate gradient, electron microscopical studies revealed that most of purified hepatocytes were well preserved and presented a normal ultrastructure, thus correlating with previous biochemical results. The present method enables the recovery of metabolically and morphologically normal hepatocytes.
Subject(s)
Animals , Male , Rats , Citrates , Liver/ultrastructure , Perchlorates , Cell Separation/methods , Sodium Compounds , Cell Survival , Centrifugation, Density Gradient , Diatrizoate , Perfusion , Rats, WistarABSTRACT
In the present study we describe a non-enzymatic technique for the isolation of rat hepatocytes by perfusion of liver through portal vein. The perfusion media consist of 1 mM sodium percholorate. 5 mM sodium citrate, 10 mM glucose, 129 mM NaCl and 0.1 per cent bovine-serum albumin at pH 7.4. After purification through diatrizoate gradient, electron microscopical studies revealed that most of purified hepatocytes were well preserved and presented a normal ultrastructure, thus correlating with previous biochemical results. The present method enables the recovery of metabolically and morphologically normal hepatocytes. (AU)
Subject(s)
Animals , Male , Rats , Cell Separation/methods , Liver/ultrastructure , Perchlorates , Sodium Compounds , Citrates , Perfusion , Diatrizoate , Centrifugation, Density Gradient , Cell Survival , Rats, WistarABSTRACT
Entre 1989 y 1994, 7 pacientes fueron tratados con pancreatectomía subtotal por hipoglucemia hiperinsulinémica persistente.Los pacientes que presentaron sintomatologá en la primera semana de vida, sufrieron formas más graves y requirieron ser operados con urgencia, mientras que aquellos con presentación tardía, pudieron ser controlados sin cirugía hasta edades mayores (13 meses,16 años, 19 años). en todos se realizó tratamiento médico y se indicó la intervención quirúrgica por hipoglucemia intratable o signos neurológicos evolutivos.La resección del 90-95 por ciento del páncreas resultó un tratamiento efectivo para la hipoglucemia por hiperinsulinemia. De los pacientes operados, sólo dos presentaron secuelas adjudicables a la intervención.Un paciente necesitó resección total luego de dos reintervenciones porque presentaba lesiones de nesidioblastosis predominantemente en la región cefálica del páncreas.El otro presentó una pancreatitis y fístula pancreática, que curó con tratamiento médico.Todos los niños presentaron hiperplasia de los islotes de Langerhans, en algunos casos difusa y en otros localizada, indetectables en el acto quirúrgico. Parece evidente que cuando áreas de hiperplasia persisten en el páncreas remanente, pueden determinar la persistencia de la enfermedad.
Subject(s)
Hypoglycemia/surgery , Pancreatectomy , PediatricsABSTRACT
Entre 1989 y 1994, 7 pacientes fueron tratados con pancreatectomía subtotal por hipoglucemia hiperinsulinémica persistente.Los pacientes que presentaron sintomatologá en la primera semana de vida, sufrieron formas más graves y requirieron ser operados con urgencia, mientras que aquellos con presentación tardía, pudieron ser controlados sin cirugía hasta edades mayores (13 meses,16 años, 19 años). en todos se realizó tratamiento médico y se indicó la intervención quirúrgica por hipoglucemia intratable o signos neurológicos evolutivos.La resección del 90-95 por ciento del páncreas resultó un tratamiento efectivo para la hipoglucemia por hiperinsulinemia. De los pacientes operados, sólo dos presentaron secuelas adjudicables a la intervención.Un paciente necesitó resección total luego de dos reintervenciones porque presentaba lesiones de nesidioblastosis predominantemente en la región cefálica del páncreas.El otro presentó una pancreatitis y fístula pancreática, que curó con tratamiento médico.Todos los niños presentaron hiperplasia de los islotes de Langerhans, en algunos casos difusa y en otros localizada, indetectables en el acto quirúrgico. Parece evidente que cuando áreas de hiperplasia persisten en el páncreas remanente, pueden determinar la persistencia de la enfermedad.
Subject(s)
Hypoglycemia/surgery , Pancreatectomy , PediatricsABSTRACT
The kallikrein-kinin system was studied in 9 normals, healthy subjects (6 men, 3 women, age range 1 to 14 years) and 15 diabetic patients (9 men, 6 women age range 2 to 14 years) with an evolution of the disease between 1 to 14 years. Diabetic patients with low microalbuminuria (6.62 +/- 0.97 mg/24 h) show increased total and pre-kallikrein respect to control (3 and 2 fold respectively). On the other hand patients with high microalbuminuria (44.7 +/- 13.2 mg/24 h) show a total and pre-kallikrein of more than 4 and 8 fold increased respectively, compare with the control. According with these results we can concluded: 1) The total kallikrein and pre-kallikrein is increased in the diabetic state. 2) When microalbuminuria is high, the total and pre-kallikrein correlates with those increasing. 3) These changes could modified the renal hemodynamic in diabetes.
Subject(s)
Diabetes Mellitus/urine , Kallikreins/urine , Adolescent , Albuminuria , Child , Child, Preschool , Diabetes Mellitus/enzymology , Diabetes Mellitus/physiopathology , Female , Glomerular Filtration Rate , Glycosuria , Humans , Infant , Male , Prekallikrein/urine , Reference ValuesABSTRACT
Definimos como "remisión diabética" la suspensión del tratamiento insulínico por un período mayor de 15 días, luego de la normalización de as glucemias y desaparición de las glucosurias. Hemos estudiado 21 niños diabéticos insulino-dependientes en el período de remisión (10 niños y 11 niñas) y 29 niños normales como control. Dos clases de pruebas fueron realizadas: glucosa intravenosa (GEV) y glucosa post-tolbutamida (GPT). Se separaron dos grupos en los niños que efectuaron la prueba de GEV. En uno se dosó glucosa, insulina, somatotrofina y glucagon plasmáticos y en el otro se determinó glucosa y péptido-C. La glucemia fue menor en los normales que en los niños en remisión. La desaparicióon de la glucosa (constante "K") fue máas alta en los normales (p < 0,001) indicando claramente el hipoinsulinismo hallado. La secreción de insulina lluego de ;a glucosa EV fue muy baja en el grupo en remisión, no pasando del valor basal. Solo dos niñas mostraron un valor normal o alto luego de la sobrecarga de glucosa y una de ellas en uns egundo estudio mostró el hipoinsulinismo común del grupo diabético en remisión. La cinética de la secreción de glucagon y somatotrofina en elg rupo en remisión fue normal, pero los niveles de glucagon fueron bajos. Cuando el área integrada (0-120 min) fue determinada para la insulina, somatotrofina y glucagon, se observó que la insulina y el glucagon eran bajos en relación a los normales (p < 0,05) y la somatotrofina igual. Sin embargo , la relación insulina/glucagon fue similar en ambos grupos. El péptido-C en la prueba de GEV mostró en los niños en remisión un valor menor que en el grupo normal semejando el comportamiento del otro grupo en remisión en donde se dosó la insulina. Durante la prueba de glucosa psot-tolbutamida, el grupo normal respondió con un pico de secreción de insulina en cada estímulo, siendo mayor la respuesta a la glucosa post-tolbutamida. En el grupo en remisión, la glucemia fue más elevada que en el grupo normal y la secreción de insulina no sobrepasó el nivel basal luego de los estímulos. La secreción de la somatotrofina en la fase de glucosa fue mas baja que en los normales y el glucagon fue consistentemente menor en este grupo. Podemos concluir que los niños en remisión no presentan una velocidad de desaparición de glucosa normal, coincidente con un marcado hipoinsulinismo. El glucagon es proporcionalmente tan bajo como la secreción de insulina, lo que permite que el índice insulina/glucagon sea similar en lo
Subject(s)
Blood Glucose/analysis , Diabetes Mellitus, Type 1/physiopathology , Glucagon/blood , Insulin/metabolism , C-Peptide/blood , Diabetes Mellitus, Type 1/blood , Glucose Tolerance Test , Insulin/adverse effects , Substance Withdrawal SyndromeABSTRACT
Definimos como "remisión diabética" la suspensión del tratamiento insulínico por un período mayor de 15 días, luego de la normalización de as glucemias y desaparición de las glucosurias. Hemos estudiado 21 niños diabéticos insulino-dependientes en el período de remisión (10 niños y 11 niñas) y 29 niños normales como control. Dos clases de pruebas fueron realizadas: glucosa intravenosa (GEV) y glucosa post-tolbutamida (GPT). Se separaron dos grupos en los niños que efectuaron la prueba de GEV. En uno se dosó glucosa, insulina, somatotrofina y glucagon plasmáticos y en el otro se determinó glucosa y péptido-C. La glucemia fue menor en los normales que en los niños en remisión. La desaparicióon de la glucosa (constante "K") fue máas alta en los normales (p < 0,001) indicando claramente el hipoinsulinismo hallado. La secreción de insulina lluego de ;a glucosa EV fue muy baja en el grupo en remisión, no pasando del valor basal. Solo dos niñas mostraron un valor normal o alto luego de la sobrecarga de glucosa y una de ellas en uns egundo estudio mostró el hipoinsulinismo común del grupo diabético en remisión. La cinética de la secreción de glucagon y somatotrofina en elg rupo en remisión fue normal, pero los niveles de glucagon fueron bajos. Cuando el área integrada (0-120 min) fue determinada para la insulina, somatotrofina y glucagon, se observó que la insulina y el glucagon eran bajos en relación a los normales (p < 0,05) y la somatotrofina igual. Sin embargo , la relación insulina/glucagon fue similar en ambos grupos. El péptido-C en la prueba de GEV mostró en los niños en remisión un valor menor que en el grupo normal semejando el comportamiento del otro grupo en remisión en donde se dosó la insulina. Durante la prueba de glucosa psot-tolbutamida, el grupo normal respondió con un pico de secreción de insulina en cada estímulo, siendo mayor la respuesta a la glucosa post-tolbutamida. En el grupo en remisión, la glucemia fue más elevada que en el grupo normal y la secreción de insulina no sobrepasó el nivel basal luego de los estímulos. La secreción de la somatotrofina en la fase de glucosa fue mas baja que en los normales y el glucagon fue consistentemente menor en este grupo. Podemos concluir que los niños en remisión no presentan una velocidad de desaparición de glucosa normal, coincidente con un marcado hipoinsulinismo. El glucagon es proporcionalmente tan bajo como la secreción de insulina, lo que permite que el índice insulina/glucagon sea similar en lo
Subject(s)
Diabetes Mellitus, Type 1/physiopathology , Blood Glucose/analysis , Glucagon/blood , Insulin/metabolism , Diabetes Mellitus, Type 1/blood , Insulin/adverse effects , C-Peptide/blood , Substance Withdrawal Syndrome , Glucose Tolerance TestABSTRACT
We define diabetic remission as the disappearance of clinical symptoms with normalization of blood glucose for a period over 15 days after withdrawal of insulin therapy. We studied 21 insulin-dependent diabetic children in remission (10 boys and 11 girls) and 29 normal children matched in age and sex as controls. Two tests were performed, intravenous glucose (IVGT) and glucose post-tolbutamide (PTGT). Two remission groups were studied with IVGT. Glucose, insulin, somatotropin and glucagon were determined in one and glucose and C-peptide in the other. Insulin secretion after IVGT was very low in the remission group, not surpassing basal value when stimulated. Only two girls showed normal or high insulin values during the study, and one of them showed the common hypoinsulinism of the remission group in a second study. The kinetics of glucagon and somatotropin secretion in the remission group were normal with low values of glucagon. When the integrated area (0-120 min) of hormone secretion (insulin, somatotropin and glucagon) was determined, the remission group had lower insulin and glucagon values (p less than 0.05) and identical growth hormone as the normal group. The insulin/glucagon ratio in normals and in remission were similar. During IVGT the remission group studied for C-peptide showed lower C-peptide values than normal group, resembling insulin behavior. In both groups, the glucose disappearance rate ("K" value) was higher in normals than in remissions (p less than 0.001). During the PTGT the normal group showed a peak of insulin secretion after tolbutamide and glucose stimulation. In the remission group, glucose was higher and insulin secretion lower than in the normal group, without a peak of insulin, and growth hormone and glucagon secretion were also lower.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Blood Glucose/analysis , Diabetes Mellitus, Type 1/physiopathology , Glucagon/blood , Insulin/metabolism , Adolescent , C-Peptide/blood , Child , Child, Preschool , Diabetes Mellitus, Type 1/blood , Female , Glucose Tolerance Test , Humans , Insulin/adverse effects , Insulin Secretion , Male , Remission InductionABSTRACT
We define diabetic remission as the disappearance of clinical symptoms with normalization of blood glucose for a period over 15 days after withdrawal of insulin therapy. We studied 21 insulin-dependent diabetic children in remission (10 boys and 11 girls) and 29 normal children matched in age and sex as controls. Two tests were performed, intravenous glucose (IVGT) and glucose post-tolbutamide (PTGT). Two remission groups were studied with IVGT. Glucose, insulin, somatotropin and glucagon were determined in one and glucose and C-peptide in the other. Insulin secretion after IVGT was very low in the remission group, not surpassing basal value when stimulated. Only two girls showed normal or high insulin values during the study, and one of them showed the common hypoinsulinism of the remission group in a second study. The kinetics of glucagon and somatotropin secretion in the remission group were normal with low values of glucagon. When the integrated area (0-120 min) of hormone secretion (insulin, somatotropin and glucagon) was determined, the remission group had lower insulin and glucagon values (p less than 0.05) and identical growth hormone as the normal group. The insulin/glucagon ratio in normals and in remission were similar. During IVGT the remission group studied for C-peptide showed lower C-peptide values than normal group, resembling insulin behavior. In both groups, the glucose disappearance rate ([quot ]K[quot ] value) was higher in normals than in remissions (p less than 0.001). During the PTGT the normal group showed a peak of insulin secretion after tolbutamide and glucose stimulation. In the remission group, glucose was higher and insulin secretion lower than in the normal group, without a peak of insulin, and growth hormone and glucagon secretion were also lower.(ABSTRACT TRUNCATED AT 250 WORDS)
ABSTRACT
Degradation of internalized insulin was studied after binding at 25 degrees C and 37 degrees C to isolated hepatocytes. The cells were washed to avoid extracellular insulin contamination. Degradation of both, intracellular and extracellular 125I-insulin, was measured with TCA and insulin antibody. In these conditions binding at 25 degrees C and 37 degrees C was equal but both intra and extracellular degradation were greater at 37 degrees C than at 25 degrees C. At both temperatures, intracellular degradation was greater than extracellular degradation with accumulation of degraded and non-degraded intracellular insulin. To study in what state hepatocytes release internalized insulin into the medium, 125I-insulin association was performed at an intermediate temperature (30 degrees C). Extracellular insulin contamination (whether associated or not) was avoided by three methods: 1) washing; 2) treatment with insulin degrading enzyme(s) and washing; 3) treatment with insulin degrading enzyme(s) then with trypsin and washing. Kinetics of radioactivity released from the cells was identical in the three conditions and the radioactivity was released throughout the experiments. Complete degradation of the released insulin was observed by gel filtration when the previous binding was 0.4 ng insulin/10(6) cells. When the dose of associated insulin increased (25 ng/10(6) cells) 3.5% of non-degraded insulin was liberated and when the dose was 14,300 ng/10(6) cells, the insulin released was 44.3%. In one experiment during the first 30 min, the insulin released was 52.88% and in the last 45 min 39.59%. To study the biologic behavior of the insulin released from cells, a group of mice were injected with this insulin (8.4 mU/mouse) and blood glucose was measured. The released insulin behaved as intact insulin as far as blood glucose responses were concerned. We may conclude that liver cells have the ability to internalize insulin and release biologically active insulin after accumulation.
Subject(s)
Insulin/metabolism , Liver/metabolism , Animals , Blood Glucose/analysis , Cells, Cultured , Kinetics , Liver/cytology , Male , Mice , Mice, Inbred BALB C , Models, Biological , Rats , Rats, Inbred Strains , Receptor, Insulin/metabolism , Temperature , Tetracaine/pharmacology , Trypsin/pharmacologyABSTRACT
It is well known that 30 to 50% of patients with Type I Diabetes develop nephropathy and that chronic renal failure, it's final pathway, is the main cause of death. Assessment of urinary albumin becomes an essential tool for identifying the population at risk of developing nephropathy, to study its physiopathologic mechanisms and to evaluate the response to therapeutic trials. The present article is a preliminary report on the study of urinary albumin excretion rate (AER) in a pediatric population with Type I Diabetes and its relation to teh duration of the disease. A RIA technique with double antibody was developed for albumin assessment, with a displacement range of 1 to 300 ng/tube. Urine samples were collected during short periods with water load as suggested by Mogensen. Thirty nine children (30 patients and 9 controls) free of renal disease and with normal blood pressure were studied. Patients were divided according to duration of the disease in: Group I: less than 5 years, Group II: 5 to 10 years and Group III: more than 10 years. Results (mean +/- SD) in micrograms/min/1.73 m2 were: Control Group (n = 9) 4.30 +/- 2.53, GI: (n = 12) 10.44 +/- 9.47, GII (n = 10) 8.03 +/- 7.27 and GIII (n = 8) 8.56 +/- 4.26. The mean value of the Control Group (+3 SD) 12 micrograms/min/1.73 m2, was considered as the upper normal limit. Thus, 16.6%, 40%, and 12.5% of children in Groups I, II and III had microalbuminuria.(ABSTRACT TRUNCATED AT 250 WORDS)
