Determination of blood ammonia by derivative spectrometry.
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Biomedical subjects
Publications and source records attributed to J Savory.
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Progress in understanding the role of trace metals in biology has been largely dependent on the development of sensitive, accurate and precise analytical methods. Atomic spectroscopic techniques, particularly atomic absorption, have made the greatest contribution. Key to the success of such analytical techniques has been the simplification of sample processing so that contamination is minimized. Electrothermal atomization has allowed sensitivity limits to be lowered sufficiently so that even ultra-trace metals can be detected. More recently, mass spectrometric detection of metal ions has added to the repertoire of available instrumentation, particularly with the use of inductively coupled plasma to introduce ions into the mass analyzer. These analyzers are suitable for multielement analysis. More conventional mass spectrometric analysis of metal chelates offer an alternate solution but require considerable specimen preparation time. Intracellular localization of trace metals necessitates complex specimen processing prior to analysis on instruments that are highly sophisticated and expensive. Metal speciation is a rapidly growing area of trace metal research, with the major advances coming from coupling of the separation process, such as capillary electrophoresis or high performance liquid chromatography, with the analytical instrument for metal detection. Inductively coupled plasma-mass spectrometry has proved to be an excellent choice for such detection purposes. Refinement of these methods as well as more widely available instruments for microanalysis will add greatly to continued advances in our knowledge of the role of trace metals in biology and medicine.
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Polyamines in serum and urine have been found to be elevated in patients with cancer. A variety of methods employed for these measurements are discussed. Normal values obtained by the most recent methods are presented, and a survey has been made of polyamine levels in cancer patients.
New methods and modifications of existing methods for the determination of amino acids in biological fluids are reviewed. The application of classical ion exhcange, gas chromatography, and combined gas chromatography/mass spectrometry methodology in the clinical biochemistry laboratory are examined and the advantages and disadvantages are noted for these techniques.
The effects of long-term aluminum exposure on erythroid parameters were investigated in a rabbit system. Healthy young adult male rabbits were maintained on drinking water containing five mg per L of aluminum citrate; others were treated with an intravenous solution of aluminum maltol, 0.225 mmol of aluminum per week. In the oral study, decreases in the hematocrit, hemoglobin, and red cell count were observed over a 12-month period in those animals on soft water with a low calcium content and containing aluminum citrate; however, no changes were seen in those on hard water containing aluminum citrate nor in rabbits maintained on a normal diet. Small amounts of aluminum were observed in bone marrow macrophages, usually accompanied by iron, in both the orally- and intravenously-treated animals. There was poor correlation between bone marrow aluminum content and length of exposure.
Procedures have been developed for the determination in serum and urine of 21 drugs which include all of the barbiturates, methyprylon, glutethimide, meprobamate, propoxyphene, methaqualone, primidone, diphenylhydantoin, methadone, codeine, morphine, amphetamine and methamphetamine. The method involves pipeting 1.0 ml of serum or urine into an extraction tube, adding an internal standard together with either a pH 4.9 or pH 8.3 buffer and extracting with chloroform. The drugs in the extract are concentrated by exaporation of the organic layer and identified and quantitated by gas-liquid chromatography (GLC) using a column packed with 3 percent OV 17. GLC analysis times are kept below seven minutes by using temperature programming which allows good separations of drugs of widely varying volatilities. All calculations are based on peak areas determined by an electronic integrator. Losses of drugs during extraction, evaporation and chromatography steps are compensated for by the use of internal standards. Actual extraction efficiencies of drugs from serum or urine range from 75 to 100 percent although recoveries, based on standards carried through the entire procedures, are quantitative. Precision (s.d.) based on replicate determinations is approximately plus or minus 0.2 mg per dl.
A stable isotope dilution gas chromatography/mass spectrometry method for the measurement of prostaglandin F2 alpha (PGF2 alpha) in plasma has been developed. The linearity of the method was 0 to 250 pg per ml, day-to-day precision of five percent at a level of 80 pg per ml, and a limit of detection of one pg per ml. Evaluation of the absolute recovery of PGF2 alpha through the sample clean-up steps using tritium labelled PGF2 alpha gave recoveries of 68 +/- 5 percent. A preliminary reference range estimated a mean plasma PGF2 alpha level of 83 +/- 13 pg per ml (n = 7) with a range of 62 to 103 pg per ml in healthy adults. The major application of this method will be in research protocols studying changes of PGF2 alpha in toxemia of pregnancy.
The effects of chelation therapy by intravenous and intraperitoneal administration of deferoxamine were compared during maintenance continuous ambulatory peritoneal dialysis (CAPD) in a child with end stage renal disease and hemosiderosis. We demonstrate that intraperitoneally administered deferoxamine is safer, more practical and efficient than weekly intravenously administered deferoxamine for the treatment of iron overload in the pediatric patient undergoing CAPD.