Document Detail

Estimation of urea production rate with [15N2]urea and [13C]urea to measure catabolic rates in diabetes mellitus.
MedLine Citation:
PMID:  9854845     Owner:  NLM     Status:  MEDLINE    
For verifying catabolic states in insulin-dependent patients and dogs the method estimating urea production rates with 13C and with doubly 15N labeled urea, respectively, has been established. For a fast steady state of urea tracer dilution, a prime of 600 times the continuous infusion rate had to be injected. Urea was isolated from plasma samples by protein precipitation and cation exchange chromatography with a consecutive derivatization of the dried urea fraction (trimethylsilyl derivatives). The masses of the fragment ions m/z 189 (14N14N), 190 (14N15N) and 191 (15N15N) urea are monitored to estimate the [15N2] urea frequency in the overall body urea pool in mol percent excess (MPE). 1 to 15 ng of derivatized urea were measured efficiently. An excellent correlation between expected standard and measured MPE (r = 0.9977) was achieved from solutions containing 1 to 7% [15N2]urea. The interassay coefficient of variation amounted to < 10% for a [15N2]urea portion of > or = 3%. Normoglycemic diabetic patients who were treated with insulin overnight showed significantly higher urea production compared to healthy controls (9.22 +/- 2.07 vs. 5.4 +/- 0.32; p < 0.05). Measurements in chronic diabetic dogs proved an increased rate of amino acid catabolism (+20% urea production) in systemic versus portal application of insulin in paired studies. This increased nitrogen load in diabetics may accelerate progression of diabetic nephropathy. Thus, the established stable isotope technique may serve as a sensitive and useful indicator of amino acid catabolism in clinical and experimental research.
E J Freyse; S Knospe
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Isotopes in environmental and health studies     Volume:  34     ISSN:  1025-6016     ISO Abbreviation:  Isotopes Environ Health Stud     Publication Date:  1998  
Date Detail:
Created Date:  1999-01-28     Completed Date:  1999-01-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9602611     Medline TA:  Isotopes Environ Health Stud     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  107-18     Citation Subset:  IM    
Institut für Diabetes Gerhardt Katsch e. V., Karlsburg, Deutschland.
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MeSH Terms
Carbon Isotopes
Case-Control Studies
Diabetes Mellitus, Type 1 / drug therapy,  metabolism*
Diabetic Nephropathies / etiology,  metabolism
Insulin / therapeutic use
Insulin Infusion Systems
Nitrogen Isotopes
Urea / administration & dosage,  metabolism*
Reg. No./Substance:
0/Carbon Isotopes; 0/Nitrogen Isotopes; 11061-68-0/Insulin; 57-13-6/Urea

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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