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D J Trafford

Publications and source records attributed to D J Trafford.

At least 55 records · Page 3Linked to original sources
PubMed1980

The estimation of vitamin D and some metabolites in human plasma by mass fragmentography.

A mass fragmentographic assay for vitamin D3, 25-hydroxyvitamin D3, 25-hydroxyvitamin D2 and 24,25-dihydroxyvitamin D3 is described. After extraction of plasma with methanol and dichloromethane, Lipidex 5000 chromatography was used to separate the plasma extract into three fractions (a vitamin D fraction, a 25-hydroxyvitamin D fraction and a 24,25-dihydroxyvitamin D fraction). Cholesterol was removed from the vitamin D fractio by thin-layer chromatography. :After addition of vitamin D2 to each fraction, isotachysterol trimethylsilyl ethers were formed. Recoveries prior to gas chromatography-mass spectrometry were assessed by the use of tritiated standards added to the plasma before extraction. Using this procedure, normal ranges were established (vitamin D3: 3--17.7, 25-hydroxyvitamin D3: 5.9--35.2, 25-hydroxyvitamin D2: 0.6---1.0 and 24,25-dihydroxyvitamin D3: 0.6--2.9 micrograms/l).

24,25-Dihydroxyvitamin D 3↗
PubMed1980

Plasma concentrations of alphaxalone by gas chromatography: comparison with other gas chromatographic methods and gas chromatography-mass spectrometry.

Existing methods for the measurement of plasma or tissue alphaxalone concentrations by gas chromatography are not wholly satisfactory because of the problems of interfering peaks and detector contamination by the silylation reagent. This paper describes an alternative gas chromatographic method using the nitrogen selective alkali flame ionization detector. Plasma samples from patients given Althesin (alphaxalone-alphadolone acetate) were extracted with light petroleum. O-Methyl oximes were formed using methoxyamine hydrochloride, and the O-methyloxime-3-acetate prepared by heating the extract with acetic anhydride-pyridine. Gas liquid chromatography was carried out on a column of 3% OV 17 ON Celite 545 (mesh 80-100), initial temperature 235 degrees C and increasing by a degree C min-1. Comparison has been made of the O-methyl oxime acetates with trimethylsilyl ethers using both gas chromatography and gas chromatography-mass spectrometry. The results of the two methods were not significantly different. The coefficient of variation for the O-methyloxime-3-acetates at a plasma concentration of 1.09 microliter-1 was 6.9%. This method has an improved sensitivity and selectivity over the existing method, and allows determination of the plasma alphaxalone concentrations found in patients receiving Althesin-supplemented anaesthesia.

Chromatography, Gas↗
PubMed1980

Defective cortisol binding globulin affinity in association with adrenal hyperfunction: a case report.

A patient with an apparent abnormality of cortisol binding globulin (CBG) is reported. Investigations showed that while the plasma CBG binding capacity (equivalent to the plasma CBG concentration) was normal, the binding affinity was reduced by a factor of four. The significance of this observation is discussed with regard to its possible role in the development of the adrenocortical hyperfunction also seen in this patient.

Adrenocortical Hyperfunction↗
PubMed1978

Effect of anticonvulsants on plasma testosterone and sex hormone binding globulin levels.

Plasma sex hormone binding globulin (SHBG) and testosterone levels were measured in 29 patients with epilepsy (16 men and 13 women), most of them on chronic therapy with anticonvulsant drugs. Sex hormone binding globulin concentrations were increased in both sexes and testosterone levels in male patients. It is postulated that anticonvulsants may induce hepatic synthesis of SHBG.

Anticonvulsants↗
PubMed1977

Male pseudohermaphroditism due to partial end-organ insensitivity to androgens.

A 46XY individual with incomplete male pseudohermaphroditism was studied. The phenotype was distinctive, with a masculine habitus despite a small phallus, gynaecomastia and diminished virilization. Plasma levels of testosterone, oestrogens, gonadotrophins and sex-hormone binding globulin were elevated. It is proposed that this syndrome is a variant of Type I incomplete male pseudohermaphroditism.

Adult↗
PubMed1976

Hydroxyapatite - a reagent for the separation of free and antibody-bound steroid during the radioimmunoassay.

The use of hydroxyapatite to absorb antibody-bound steroid and thus separate free and antibody-bound steroid during radioimmunoassay has been examined using three steroid antisera (to testosterone, to 17-hydroxyprogesterone and to estradiol-17beta). For all three antisera studied the separation was shown to be independent of length of time in contact with hydroxyapatite (up to 1h); temperature variations from 4 degrees -37 degrees and pH over the range 4.9-8.0. The presence of protein affected the absorption of antibody-bound steroid but this effect could be overcome by the addition of increasing amounts of hydroxyapatite. Further increase in the amount of hydroxyapatite added had no effect on the separation of free and bound steroid. Sodium phosphate buffers of molarity greater than 0.01M eluted antibody-bount steroid from hydroxyapatite, but Tris-HC1 buffers up to molarities of 0.1 M had no effect. Hydroxyapatite when used as a dry powder had the same effects as suspensions. No effect on the cross-reactivities of the antisera used could be demonstrated when hydroxyapatite was used and plasma testosterone assays on 22 plasma samples using hydroxyapatite gave essentially the same results as assays on the plasma using a coated-tube assay. Hydroxyapatite can also be successfully pumped along small bore plastic tubing without settling and can thus be used in automated immunoassay systems.

Estradiol↗
PubMed1968

The partial characterization of 1-oxygenated steroids from urine of a hypertensive newborn child.

1. Four substances from the urine of a hypertensive newborn girl were partially characterized and shown to be 17alpha-hydroxy-5beta-pregnane-1,3,20-trione, 3alpha,17alpha-dihydroxy-5beta-pregnane-1,20-dione, 3alpha,17alpha,20alpha-trihydroxy-5beta-pregnan-1-one and 5beta-pregnane-1beta,3alpha,17alpha,20alpha-tetrol. 2. The characterization rested mainly on R(M) analysis of the substances and their derivatives by glycol fission, providing evidence for position and degree of substitution and for steroidal character. Supporting evidence was provided by chemically specific location reactions. 3. Certain problems in the manipulation of these beta-disubstituted steroids are discussed.

Chemical Phenomena↗
PubMedDate not supplied

Gas chromatography-mass spectrometry and the measurement of vitamin D metabolites in human serum or plasma.

Although methods for the measurement of vitamin D metabolites continue to be developed, few have been properly validated by comparison with methods based on gas chromatography-mass spectrometry, widely accepted as being the definitive methodology. To the best of our knowledge, only three such comparisons have been carried out (14, 42, 83), all three examining HPLC assays for 25-OH-D. This lack of proper validation leads to lack of certainty as to the specificity of many assays widely used for clinical investigation. In our view there is an obvious need for the continuing development of mass fragmentographic assays for vitamin D and its metabolites, primarily for use as reference procedures for the evaluation of less rigorous methodologies. Provided standards, both labeled and unlabeled, become more widely available, development of specific mass fragmentographic assays for any metabolite of vitamin D should be possible. For metabolites where no specific binding protein or antiserum is available, mass fragmentography may be the only alternative.

Gas Chromatography-Mass Spectrometry↗