General Methods

Hormones - RIA

  • Used to measure ACTH, corticosterone, cortisol, c-peptide, ghrelin, glucagon (also available by ELISA; see below), insulin, leptin, PYY, testosterone, T3 and T4
  • Hormones are assayed by RIA using a double antibody procedure, allowing for the detection of minute concentrations of biological (hormones) or pharmacological substances in blood or other fluid samples using antigen/antibody reactions.
  • The method provides a very sensitive, inexpensive method of measurement.
  • Final analysis is accomplished by quantifying the bound radioactive counts with a Packard Gamma counter connected to a computerized data reduction station.
  • These assays are high volume and their major benefit is in accuracy and cost savings.
  • See the Assays page for vendor information
  • See the Sample Prep page for information about sample collection / required additives

Glucagon - ELISA

  • In addition to the traditionally used RIA (see above) we now also offer analysis by the Mercodia Glucagon ELISA.
  • This is a high quality two-site enzyme sandwich immunoassay for sensitive and specific determination of glucagon.
  • There is little or no cross-reactivity to peptides oxyntomodulin, glicentin, mini-glucagon, GLP-1, GLP2 and GRPP. In contrast, ~20% of what is measured in the glucagon RIA is non-specific cross reacting material. 
  • Other advantages include low sample volume requirements (20 µl for duplicate analysis) and high sensitivity (2-180 pmol/L measurement range).
  • See also: Specificity and sensitivity of commercially available assays for glucagon and oxyntomodulin measurement in humans

Catecholamines - HPLC

  • Plasma norepinephrine and epinephrine are routinely measured by HPLC via electrochemical detection. Dopamine is not measured. 
  • Plasma is absorbed onto alumina at a ph of 8.6, eluted with dilute perchloric acid, and auto-injected onto a c18 reversed-phase column.
  • An internal standard (dehydroxylbenzylamine/DHBA) is included with each extraction to monitor recovery and aid in quantification.
  • Results are quantified through a chromatography data station.
  • This service is widely used and provides a precise and sensitive estimate of catecholamine levels in biologic tissues and fluids.
  • Catecholamines are unstable. See the Sample Prep page for information about sample collection, required additives, and tissue prep.

Amino Acids - HPLC

  • Performed by HPLC using the dedicated Biochrom 30 amino acid analyzer, using lithium-based ion exchange with post-column ninhydrin, which is then analyzed to procure quantitative results. Sample preparation entails deproteinizing plasma with sulfosalicylic acid and adding lithium loading buffer to adjust the pH to an ideal level.
  • The following can be measured: 1-Methylhistidine, 3-Methylhistidine, Alanine, Ammonia, Anserine, Arginine, Asparagine, Aspartic Acid, Carnosine, Citrulline, Cystathionine, Cysteine, Ethanolamine, Glutamic Acid, Glutamine, Glycine, Histidine, Homocystine, Hydroxylysine-1, Hydroxylysine-2, Hydroxyproline, Isoleucine, Leucine, Lysine, Methionine, Norleucine, Ornithine, Phenylalanine, Phosphoethanolamine, Phosphoserine, Proline, Sarcosine, Serine, Taurine, Threonine, Tryptophan, Tyrosine, Urea, Valine, α-Aminoadipic acid, α-Aminoisobutyric acid, α-Amino-n-butyric acid, β-Alanine, γ-aminobutyric acid
  • An abbreviated "gluconeogenic" selection can be run at a lower cost: Alanine, Asparagine, Aspartic Acid, Glutamic Acid, Glutamine, Glycine, Serine, Threonine, Urea 
  • See the Sample Prep page for information about tissue prep.

Nucleotides - HPLC

  • An HPLC method was developed for the separation and quantification of AMP, ADP, ATP, ZMP and cAMP in tissue samples.
  • Separation is achieved within 30 minutes on a LC18-T chromatography column.
  • Detection is carried out using a Waters 490 UV detector.
  • These methods are unique and sensitive. Assays are carried out sporadically as the need arises.
  • See the Sample Prep page for information about tissue prep.

Luminex multiplex

  • This instrument allows for the x-map analysis of multiple analytes from a single small aliquot of sample.
  • See the Luminex page for more information.

Glucose - enzymatic 

​Lipids

 

***This core is supported by NIH grant DK020593 (DRTC). Please acknowledge this in your publications.***