1/15. gene expression and serum levels of insulin-like growth factors (IGFs) and IGF-binding proteins in a case of non-islet cell tumour hypoglycaemia.We describe a case of non-islet cell tumour hypoglycaemia (NICTH) associated with a renal cell carcinoma. serum insulin-like growth factors (IGFs) (including IGF-II E peptide), IGF-binding proteins (IGFBPs), insulin and c-peptide were measured before and after surgical removal of the tumour. IGFBPs were visualized by Western ligand blotting. Preoperatively 'big' IGF-II and IGFBP-2 levels were raised. IGF-I, IGFBP-1 and IGFBP-3 were low, while insulin, c-peptide and GH were undetectable. These changes were reversed by 2 days postoperatively. Protease assays showed little IGFBP-3 protease activity preoperatively. Preoperatively, neutral chromatography demonstrated most of the immunoassayable IGFBP-3 in a high molecular weight form with a small amount of IGF-II. Most of the IGF-II and big IGF-II eluted in lower molecular weight forms. Postoperative samples showed a shift in IGF-II which became increasingly associated with IGFBP-3 in both low and high molecular weight complexes. By Northern blotting, expression of all species of IGF-II mRNA in the tumour was 10-fold greater than in normal human liver. The tumour did not express IGFBP-1 or IGFBP-2. IGFBP-3 was expressed in small amounts, while the expression of IGFBP-4 was two-fold higher than in liver. In conclusion, we have confirmed high levels of big IGF-II and IGFBP-2 in NICTH, changes which are reversed postoperatively. The IGF-II is derived from the tumour which overexpresses these genes but IGFBP-2 probably arises from extratumour upregulation.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
2/15. Hypoglycaemia due to insulin autoimmune syndrome: report of two cases with characterisation of HLA alleles and insulin autoantibodies.OBJECTIVE: Insulin autoimmune syndrome (IAS) has been reported mainly in japan and so far only 27 IAS cases have been described from outside asia. We describe two unrelated Portuguese patients with IAS and characterise their insulin autoantibodies and HLA alleles. patients: Patient 1, a 24-year-old white female suffered an episode of unconsciousness in the late postprandial state and blood glucose was found to be 33 mg/dl with serum insulin levels of >3980 microIU/ml (normal range 0-30 microIU/ml). She was receiving monthly injections of penicillin g for the prophylaxis of recurrent tonsillitis. Patient 2, was a 19-year-old white female, with episodes of sweating, hand tremor, weakness and hunger occurring in the postprandial state and blood glucose levels during the attacks of 28-56 mg/dl. Very high insulin levels (602-708 microIU/ml) were present. methods AND RESULTS: Anti-insulin antibodies, determined by a semi-quantitative method, were strongly positive in both patients (91.7% in patient 1 and 88.6% in patient 2; normal range < or =7%). Sephadex G-100 chromatography of the sera showed most of insulin immunoreactivity present in the void volume which was retained by an affinity column with anti-human-immunoglobulin g antibodies (87% and 95% from patients 1 and 2 respectively). Scatchard plot analysis and molecular typing of the DRB1 gene revealed a polyclonal antibody and DRB1*0406 in patient 1, and a monoclonal antibody and DRB1*0403 in patient 2. CONCLUSIONS: These two Portuguese patients with IAS had different HLA-DR4 subtypes and insulin autoantibodies: DRB1*0406 and a polyclonal antibody in a patient treated with penicillin, and DRB1*0403 and a monoclonal antibody in a patient with "idiopathic" IAS.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
3/15. An insulin-like growth factor ii-producing histiocytoma associated with hypoglycemia: analysis of the peptide, its gene expression, and glucose transporter isoforms.An insulin-like growth factor ii (IGF-II)-producing histiocytoma was detected in a patient presenting with the classical findings of tumor-related hypoglycemia (low serum insulin and IGF-I concentrations, glucose intolerance, and only modestly increased serum IGF-II levels). Acid-gel filtration of serum extracts showed a single peak of IGF-II immunoreactivity that emerged at the same site as the 125I-labeled human IGF-II standard. High-performance liquid chromatography (HPLC) analysis of the tumor IGF-II demonstrated that it had an identical retention time to that of recombinant human IGF-II. The tumor IGF-II content was extremely high, messenger rna (mRNA) for IGF-II showed a 100-fold increase in expression compared with normal human liver tissue. Of special interest, a newly identified exon (hE1) was shown to be predominantly expressed in the tumor by Northern blot analysis using leader exon-specific rat IGF-II complementary dna (cDNA) probes. Although the significance of this finding remains uncertain, this is the first evidence of a new transcription unit in the human IGF-II gene. In addition, immunoblotting showed that the levels of the glucose transporters, GLUT1 and GLUT4, in the tumor were low and undetectable, respectively. This finding makes it unlikely that increased glucose consumption by the tumor accounted for the hypoglycemia in this patient. This case report provides an interesting insight into the pathophysiology of tumor-induced hypoglycemia and new evidence of the abnormal regulation of IGF-II gene expression in human tumors.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
4/15. hypoglycemia due to surreptitious injection of insulin. Identification of insulin species by high-performance liquid chromatography.OBJECTIVE: To identify the circulating species of insulin after separation by high-performance liquid chromatography (HPLC) in patients with factitious hypoglycemia. research design AND methods: In three of four patients presented, the diagnosis of surreptitious insulin injection was made by documenting the presence of animal insulin in the circulation after separation of the circulating insulin forms by HPLC. RESULTS: Animal insulin was identified. CONCLUSIONS: Thus, the identification of the circulating form of insulin in the circulation by HPLC may be a useful adjunct in the diagnosis of factitious hypoglycemia if animal insulin has been injected and if the simultaneously measured concentrations of insulin and c-peptide are inconclusive.- - - - - - - - - - ranking = 5keywords = chromatography (Clic here for more details about this article) |
5/15. Deficiency of long-chain 3-hydroxyacyl-coa dehydrogenase: a cause of lethal myopathy and cardiomyopathy in early childhood.A child presented in early childhood with episodes of coma and hypoglycemia and a rapidly evolutive myopathy and cardiomyopathy leading to death at 9 mo of age. ketosis was decreased (blood beta-hydroxybutyrate: 0.07 mmol/L) despite normal plasma levels of fatty acids (0.81 mmol/L). The patient's urine contained excessive amounts of the C6 to C10 dicarboxylic acids present in almost all defects of fatty acid mitochondrial oxidation. More specifically, gas chromatography-mass spectrometry identified an accumulation of medium- and long-chain (C8 to C14) 3-hydroxy-dicarboxylic acids, suggesting a defect of the mitochondrial enzyme that normally dehydrogenates these 3-hydroxyacyl-CoA esters. Biochemical studies in the patient's cultured fibroblasts confirmed the impairment of medium- and long-chain fatty acid oxidation, and allowed the recognition of the deficiency of long-chain 3-hydroxyacyl-coa dehydrogenase. The activities of long-, medium-, and short-chain acyl-coa dehydrogenases and 3-ketoacyl-CoA thiolase were normal. These results describe a disorder of fatty acid metabolism that affects the liver, skeletal muscles, and myocardium. It is important to point out that long-chain 3-hydroxyacyl-CoA deficiency shares many clinical similarities with systemic carnitine deficiency, as well as with carnitine-palmityl-CoA transferase and long-chain acyl-CoA dehydrogenase deficiencies. The differential diagnosis of this disease relies on the demonstration of long-chain urinary dicarboxylic acids with a hydroxyl group in 3-position and the study of the enzyme activity in cultured fibroblasts.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
6/15. Aberrant insulinoma in the duodenum.A rare case of aberrant insulinoma in the duodenum is described. Hyperinsulinemia with typical hypoglycemic symptoms was induced by prolonged fasting. Selective angiography demonstrated a tumor supplied from the first branch of the jejunal artery, and duodenoscopy revealed a submucosal tumor at the third portion of the duodenum. An increase in venous plasma immunoreactive insulin concentration was evident in the vein draining from the tumor, by sampling through percutaneous transhepatic catheterization. hypoglycemia was ameliorated after the removal of the submucosal tumor of the duodenum. Histologic and immunocytochemical characterization of the tumor showed an insulinoma, predominantly composed of cells with typical B-cell-like granules. The acid extract of the tumor contained 1.2 U/g of insulin, and this insulin, analyzed by reverse-phase high-pressure liquid chromatography, revealed that it had the same amino acid structure as that of human insulin.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
7/15. 3-Hydroxyoctanoic aciduria: identification of a new organic acid in the urine of a patient with non-ketotic hypoglycemia.A four-month-old child with non-ketotic hypoglycemia and rapidly progressive cirrhosis excreted in her urine large amounts of two unidentified organic acids in addition to a spectrum of saturated, unsaturated, and 3-hydroxy dicarboxylic acids in her urine. Gas chromatography/mass spectrometry of the trimethylsilyl derivative of one of the unknown compounds suggested the structure of 3-hydroxyoctanoic acid, which was confirmed by similar analysis of the authentic compound. The same organic acid was found in the child's plasma. The significance of 3-hydroxyoctanoic aciduria as a possible marker for a primary defect of 3-hydroxy fatty acid metabolism is discussed.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
8/15. Clinical and biochemical aspects of the insulin autoimmune syndrome (IAIS).A 44-year old patient presented with recurrent hypoglycemic attacks after ingestion of carbohydrates. High insulin levels in the range of 350 microU/ml (normal range less than 20 microU/ml) were detected which rose to peak levels of 2,460 microU/ml (normal range less than 300 microU/ml) after oral glucose. The apparently high insulin concentrations were caused by insulin autoantibodies interfering in the radioimmunoassay (RIA) system (and thus with correct insulin quantitation). 125I-insulin added to the patient's serum was not bound to dextran-coated charcoal but was precipitated with antihuman IgG serum. The antibodies bound human, porcine, and bovine insulin with similar affinity. Following Sephadex G-50 gel filtration, the patient's insulin eluted after the void volume. Free insulin was extracted from serum using Sep-Pak C 18 cartridges and characterized by high pressure liquid chromatography (HPLC); it eluted similarly to synthetic human insulin. Quantitation of free insulin during a hypoglycemic attack (3.5 h after oral glucose, with a blood sugar of 20 mg/dl) showed an increased insulin level of 50 microU/ml. Insulin receptor concentration on erythrocytes was near the lower normal limit. We believe that the insulin antibodies present in this patient's serum (who supposedly never received insulin) led to the formation of a large circulating insulin pool, binding the insulin released after glucose stimulation, and causing hypoglycemias by delayed postprandial liberation of bound insulin.- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
9/15. Antibodies to insulin receptor followed by anti-idiotype. Antibodies to insulin in child with hypoglycemia.A child presenting severe hypoglycemia despite low or normal secretion of insulin was found to have IgM antibodies to the insulin receptor. These antibodies stimulated lipogenesis in fat cells in vitro and competed with insulin for binding to insulin receptors. After treatment with glucocorticoids, the anti-receptor antibodies and the hypoglycemia both disappeared, and antibodies to insulin appeared in the patient's serum. The anti-insulin antibodies were isolated by affinity chromatography and were found to inhibit the anti-insulin-receptor antibodies that were present earlier. The interaction between the patient's anti-insulin antibodies and his anti-receptor antibodies suggests that these two species of antibodies are related as idiotypes and anti-idiotypes. We also studied the interaction of the hypoglycemic patient's anti-receptor antibodies with anti-insulin antibodies of a diabetic patient and with anti-insulin antibodies of mice immunized to insulin. The hypoglycemic patient's anti-receptor antibodies were neutralized by the diabetic patient's anti-insulin antibodies, indicating that anti-insulin antibodies with a common idiotype may arise in both diabetes and hypoglycemia. Moreover, mouse anti-insulin antibodies that interacted with mouse anti-receptor antibodies neutralized the hypoglycemic patient's anti-receptor antibodies. In contrast, mouse anti-insulin antibodies that did not interact with the mouse anti-receptor antibodies did not neutralize the hypoglycemic patient's anti-receptor antibodies. Thus, the human anti-insulin antibodies share an idiotype with a specific class of mouse anti-insulin antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)- - - - - - - - - - ranking = 1keywords = chromatography (Clic here for more details about this article) |
10/15. High performance liquid chromatography used to distinguish the autoimmune hypoglycemia syndrome from factitious hypoglycemia.Recurrent episodes of spontaneous hypoglycemia developed in a 30-yr-old woman who had received a brief course of insulin therapy 10 yr previously. She denied surreptitious insulin administration, and the autoimmune hypoglycemia syndrome was considered. Her insulin levels could not be reliably measured because of the presence of circulating antiinsulin antibodies, which interfere with standard RIA techniques. Reverse phase high performance liquid chromatographic analysis of serum obtained during a hypoglycemic episode revealed a mixture of beef and pork insulins but no human insulin, firmly establishing the diagnosis of factitious hypoglycemia. This case illustrates the value of reverse phase high performance liquid chromatography in characterizing patients in whom the autoimmune hypoglycemia syndrome is suspected.- - - - - - - - - - ranking = 5keywords = chromatography (Clic here for more details about this article) |
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