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Core Lab
Hormone Assays: The following assays of plasma hormones were offered initially:
Recent additions: The purchase of a radiometric detector by the GCRC for the HPLC system in the Department of Surgery, has enabled the assay of Catecholamines and DOPA to be offered also. By continual update and improvement of techniques, quality will be enhanced, with expansion of range of hormones to be assayed, in response to requests by GCRC users. Plasma metabolites and other substances: Initially the Core Laboratory offered assays of glucose in blood and plasma. Recent additions: The purchase by the GCRC of a special column for the HPLC in the Dept. of Surgery has allowed measurements of amino acid profiles in physiological fluids and protein hydrolysates to be offered. Measurement of the plasma concentration of Indocyanine green in plasma will also be performed, to facilitate the determination of plasma volume and blood flow. Mass Spectrometry: Initially the facility provided the following range of services: i) Analysis of isotopic enrichments in samples containing: the isotopes 13C, 2H, and 15N in amino acids from blood, tissues, urine, saliva, tissue proteins and plasma proteins; 2H and 13C in keto acids from blood, tissues, urine and saliva. ii) Protocols for measuring: whole-body protein turnover with 13C labeled amino acids; oxidation rates of amino acids and other compounds by monitoring the production of 13CO2; body bicarbonate kinetics; glucose entry rate; gluconeogenesis from amino acids and other precursors; nitrate biosynthesis from 15N]arginine; protein synthesis rates in tissues taken by biopsy (eg. muscle, liver, colon, heart, stomach, tumors); protein synthesis and degradation, glucose entry and gluconeogenesis in organs/limbs by arterio-venous difference; synthesis of plasma proteins. New Developments: Currently, the enrichment of glucose and glycerol labeled with 2H and 13C is measured in a commercial laboratory, but the techniques for performing this assay in the Core Laboratory are currently being established. Special protocols are also being developed for the following:- measurement of whole-body and tissue protein turnover in preterm infants; use of groups of differently labeled tracers for repeating measurements of tissue protein synthesis in the same subject (eg. [2H5phenylalanine followed by [1-13C]phenylalanine), without incurring an increase in baseline enrichment; studies of intracellular pools and precursor compartmentation; more sensitive methods of analysis of amino acids from tissue protein hydrolysates [eg. 2], permitting measurements when only very small biopsies are available and allowing measurements on individual cell types and specific proteins. The Core laboratory also interfaces with commercial or other GCRC laboratories for measurement of isotopes and labels that require instruments not available to the Stony Brook GCRC (eg. breath 13CO2 or urinary 15NO3- by Gas Isotope Ratio Mass Spectrometry - GCIRMS). General Services:
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