A novel radioassay for the determination of folate in serum and red cells and new observations on the stability of serum folate
Description
A Competitive Protein Binding assay for the determination of folate in serum and red cells has been developed. The assay has been fully validated in hospital trials and comparisons have been made with the microbiological assay. We have based the standardization of the radioassay on N5-methyltetrahydrofolate (N5-MTHF) as this is the predominant folate derivative in serum samples. At about pH 9.5 pteroylglutamic acid (PGA) and N5-MTHF demonstrate the same affinity for folate binding proteins. Therefore, many folate assays have adopted PGA largely because of the popular belief that N5-MTHF is highly unstable. However, we have demonstrated that N5-MTHF in serum standards is surprisingly stable at -200C. All the reagents for the assay (including the N5-MTHF standards) have shown perfectly acceptable stability, permitting their storage for at least three weeks at -200C and one week at 40C. Evidence will be presented to support the use of N5-MTHF as being the more appropriate standard. Folate in human serum samples is stable even at room temperature in the presence of 0.1% sodium azide. (orig./AJ)
Availability note (English)
MF available from INIS under the Report Number.Abstract (German)
Es wurde ein Proteinbindetest zur Bestimmung von Folat im Serum und roten Zellen entwickelt. Der Test wurde in Krankenhaeusern ausprobiert und es wurden Vergleiche mit dem mikrobiologischen Test gemacht. Wir haben als Grundlage die Standardisierung des Radiotests auf N5-Methytetrahydrofolat (N5-MTHF) genommen, da dies das dominierende Folatderivat in Serumproben ist. Bei ca. pH 95, zeigen Pterylglutaminsaeure (PGA) und N5-MTHF die gleiche Affinitaet zu folatbindenden Proteinen. Deshalb haben viele Folattests PGA weitgehend aufgenommen, da allgemein der Glaube herrscht, dass N5-MTHF sehr unstabil sei. Wir haben jedoch gezeigt, dass N5-MTHF bei -200CC ueberraschend stabil ist. Alle Reagenzien fuer den Test (einschliesslich der N5-MTHF-Standards) zeigten durchwegs annehmbare Stabilitaet, die es gestattet, dass sie fuer mindestens 3 Wochen bei -200C und eine Woche bei 40C gespeichert werden koennen. Es werden Beweise dafuer aufgefuehrt, dass N5-MTHF der bessere Standard ist. Folat in menschlichen Serumproben ist sogar bei Zimmertemperatur unter Vorhandensein von 0,1% Natrium-Azid stabil. (orig./AJ)
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Additional details
Publishing Information
- Imprint Pagination
- 8 p.
- Report number
- AED-Conf--77-461-020
Conference
- Title
- International symposium on radioimmunoassay and related procedures in medicine.
- Dates
- 31 Oct - 4 Nov 1977.
- Place
- Berlin, Germany, F.R.
INIS
- Country of Publication
- Germany
- Country of Input or Organization
- Germany
- INIS RN
- 9386236
- Subject category
- S60: APPLIED LIFE SCIENCES;
- Resource subtype / Literary indicator
- Conference
- Descriptors DEI
- BLOOD SERUM; DIAGNOSTIC TECHNIQUES; ERYTHROCYTES; FOLIC ACID; LABELLED COMPOUNDS; NUCLEAR MEDICINE; RADIOIMMUNOASSAY; SELENIUM 75; STORAGE
- Descriptors DEC
- AMINO ACIDS; BETA DECAY RADIOISOTOPES; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; CARBOXYLIC ACIDS; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; EVEN-ODD NUCLEI; HETEROCYCLIC COMPOUNDS; HYDROXY COMPOUNDS; INTERMEDIATE MASS NUCLEI; ISOTOPE APPLICATIONS; ISOTOPES; MEDICINE; NUCLEI; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PTERIDINES; RADIOISOTOPES; SELENIUM ISOTOPES; TRACER TECHNIQUES; VITAMIN B GROUP; VITAMINS
Optional Information
- Notes
- 2 figs.; 3 tabs.; 12 refs.
- Secondary number(s)
- IAEA-SM--220/32.