High-Performance Liquid Chromatographic Determination of Insulin in Rat and Human Plasma

Khaksa, G; Nalini, K; Bhat, Mohd Shafi; Udupa, N.

doi:10.1006/abio.1998.2660

Cited by 30 publications

(17 citation statements)

References 8 publications

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“…Insulin from the cell culture media of ARIP cells was isolated using the method described by Khaksa et al for rat and human blood plasma high-performance liquid chromatography (HPLC) analyses (20). In brief, 1 ml of the cell culture medium was removed and treated with 1 ml of dichloromethane by rotating for 5 min.…”

Section: Stable Isotope Based Metabolic Profilingmentioning

confidence: 99%

GLP-1 stimulates glucose-derived de novo fatty acid synthesis and chain elongation during cell differentiation and insulin release

Bulotta

Perfetti

Hui

et al. 2003

Journal of Lipid Research

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Glucagon-like peptide-1 (GLP-1, 7-36) is capable of restoring normal glucose tolerance in aging, glucose-intolerant Wistar rats and is a potent causal factor in differentiation of human islet duodenal homeobox-1-expressing cells into insulin-releasing ␤ cells. Here we report stable isotope-based dynamic metabolic profiles of rat pancreatic epithelial (ARIP) and human ductal tumor (PANC-1) cells responding to 10 nM GLP-1 treatment in 48 h cultures. Macromolecule synthesis patterns and substrate flow measurements using gas chromatography/mass spectrometry (MS) and the stable [1,2-13 C 2 ]glucose isotope as the tracer showed that GLP-1 induced a significant 20% and 60% increase in de novo fatty acid palmitate synthesis in ARIP and PANC-1 cells, respectively, and it also induced a significant increase in palmitate chain elongation into stearate utilizing glucose as the primary substrate. Distribution of 13 C in other metabolites indicated no changes in the rates of nucleic acid ribose synthesis, glutamate oxidation, or lactate production. Tandem Glucagon-like peptide-1 (GLP-1; 7-36) of the intestine enhances insulin secretion from pancreatic ␤ cells in response to food intake and restores normal glucose tolerance in glucose-intolerant aging Wistar rats (1). Expression of insulin mRNA and high insulin contents were described after transfection of insulinoma cells with the GLP-1 receptor in epithelial cells of the pancreas (2). Additionally, both rat and human cells readily differentiate into insulin-secreting cells in response to GLP-1 treatment (3, 4). Cell differentiation and insulin release by pancreatic cells in response to GLP-1 require the presence of functioning specific receptors and the presence of the islet duodenal homeobox-1 (PDX-1) transcript protein, which translocates to the nucleus (5). This process is triggered by a ligand-induced activation of adenylyl cyclase that increases intracellular cAMP levels, which, in turn, activate protein kinase A during epithelial cell differentiation (6, 7).Stable isotope-based dynamic metabolic profiling (SID-MAP) technology helps detail mechanisms of hormone actions by revealing genotype-phenotype-metabolome interactions and by tracking metabolic pathway substrate flow changes ( Fig. 1 ) (8, 9). Fatty acid metabolism appears to be a critical factor in cell differentiation and in mediating the antitumor activities of newly characterized potent kinase targeting treatment modalities (10-13). In the present study, we have investigated the metabolic substrate flow regulating effects of GLP-1 in two epithelial tumor cell lines, which both differentiate into insulin-secreting ␤ -like cells in culture. This paper demonstrates that cell differentiation and regulation of insulin release after GLP-1 treatment are accompanied by important metabolic adaptive changes that primarily affect the contribution of glucose to de novo fatty acid synthesis and chain elongation of the saturated long-chain species primarily utilized for triglyceride and membrane synthesis. MATERIAL...

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Section: Stable Isotope Based Metabolic Profilingmentioning

confidence: 99%

GLP-1 stimulates glucose-derived de novo fatty acid synthesis and chain elongation during cell differentiation and insulin release

Bulotta

Perfetti

Hui

et al. 2003

Journal of Lipid Research

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“…Finally, plasma insulin concentration is determined from the standard curve of insulin. Owing to the small sample volume required, this procedure is particularly suitable for paediatric microsamples [31].…”

Section: Enzymatic Techniques Please Refer To "Enzymatic Techniques" mentioning

confidence: 99%

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the area of blood glucose and insulin concentrations

et al. 2018

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Most requests for authorization to bear health claims under Articles 13(5) and 14 related to blood glucose and insulin concentration/regulation presented to the European Food Safety Authority (EFSA) receive a negative opinion. Reasons for such decisions are mainly ascribable to poor substantiation of the claimed effects. In this scenario, a project was carried out aiming at critically analysing the outcome variables (OVs) and methods of measurement (MMs) to be used to substantiate health claims, with the final purpose to improve the quality of applications provided by stakeholders to EFSA. This manuscript provides a position statement of the experts involved in the project, reporting the results of an investigation aimed to collect, collate and critically analyse the information relevant to claimed effects (CEs), OVs and MMs related to blood glucose and insulin levels and homoeostasis compliant with Regulation 1924Regulation /2006. The critical analysis of OVs and MMs was performed with the aid of the pertinent scientific literature and was aimed at defining their appropriateness (alone or in combination with others) to support a specific CE. The results can be used to properly select OVs and MMs in a randomized controlled trial, for an effective substantiation of the claims, using the reference method(s) whenever available. Moreover, results can help EFSA in updating the guidance for the scientific requirements of health claims.

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“…The pH of both the donor and receptor solutions were measured after iontophoresis and the sample from the donor compartment was analysed by TLC, SDSpolyacrylamide gel electrophoresis (SDS-PAGE) and HPLC in addition to testing for hypoglycaemic activity. A modified HPLC method (Khaksa et al 1998) was followed for analysis of insulin. The mobile phase was composed of acetonitrile and sodium sulfate (0.2 M) in the ratio of 25:75.…”

Section: Hplc Analysismentioning

confidence: 99%

Transdermal iontophoresis of insulin. Part 1: A study on the issues associated with the use of platinum electrodes on rat skin

Pillai

Kumar

Dey

et al. 2003

Journal of Pharmacy and Pharmacology

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We have studied the issues associated with the use of platinum electrodes for transdermal iontophoretic delivery of peptides, using insulin as a model peptide. Insulin permeation was studied using full-thickness rat skin by varying the donor solution pH as a function of electrode polarity. The stability of insulin under the iontophoretic conditions was studied using TLC, SDS-polyacrylamide gel electrophoresis and HPLC. Large pH shifts were observed during anodal iontophoresis (AI), when the donor solution pH was above the isoelectric point of insulin and in cathodal iontophoresis (CI), when the donor solution pH was below the isoelectric point of insulin. The direction and magnitude of electroosmotic flow was influenced by pH of the donor solution and the electrode polarity. On the other hand, the buffer used to maintain the pH governed the contribution of electrorepulsion to the overall transport of insulin. Electrochemical degradation of insulin was significant during AI at pH 7.4. Among the pH investigated, AI of insulin at pH 3.6 and CI at pH 8.35 were better, as the pH shift was relatively less and electrochemically more stable during iontophoresis as compared with other pH. In summary, the pH shift caused by platinum electrodes had a significant influence on the permeation and stability of insulin.

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High-Performance Liquid Chromatographic Determination of Insulin in Rat and Human Plasma

Cited by 30 publications

References 8 publications

GLP-1 stimulates glucose-derived de novo fatty acid synthesis and chain elongation during cell differentiation and insulin release

GLP-1 stimulates glucose-derived de novo fatty acid synthesis and chain elongation during cell differentiation and insulin release

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the area of blood glucose and insulin concentrations

Transdermal iontophoresis of insulin. Part 1: A study on the issues associated with the use of platinum electrodes on rat skin

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