Biomedical subjects

R Mallein

Publications and source records attributed to R Mallein.

At least 19 recordsLinked to original sources

PubMed1989

Radioimmunoassay of testosterone not bound to sex-steroid-binding protein in plasma.

To measure the concentration of testosterone (T) that is not bound to sex-steroid-binding protein (SBP) in plasma, we quantified by radioimmunoassay the T in the supernates of plasma samples after precipitation with 50%-saturated ammonium sulfate. The concentrations of non-SBP-bound T. directly measured with this assay, correlated significantly (P less than 0.001) with those deduced from measurement of the percentage of non-SBP-bound T determined with [3H]T as tracer or from mathematical models according to the law of mass action. It also correlated significantly with the ratio of T to SBP and with the concentration of nonbound T. As determined with this assay, the mean concentration of non-SBP-bound T in normal men was higher in young (4.67, SD 2.68 nmol/L; n = 30) than in older (greater than 40 years) subjects (2.48, SD 1.61 nmol/L; n = 35; P less than 0.001) and lower than normal in hyperthyroid (1.61, SD 0.91 nmol/L; P less than 0.01) or infertile men (3.28, SD 1.70 nmol/L; P less than 0.01). In women, non-SBP-bound T was higher in hirsute patients (0.24, SD 0.11 nmol/L; P less than 0.01) and was lower during pregnancy (0.09, SD 0.05 nmol/L; P less than 0.05) than in normal women during the follicular phase (0.16, SD 0.07 nmol/L). We conclude that this direct measurement of non-SBP-bound T in plasma is suitable for routine use and represents a reliable index of androgenicity in human pathology, particularly when alterations of the binding capacity of SBP modify the concentrations of total T.

Adult↗

PubMed1988

New approach to competitive lanthanide immunoassay: time-resolved fluoroimmunoassay of progesterone with labeled analyte.

This solid-phase competitive europium immunoassay of progesterone in plasma relies on antigen labeling. With this new approach, time-resolved fluoroimmunoassay can attain sensitivity and precision similar to that of conventional radioimmunoassay. The europium-labeling involves coupling diethylenetriaminepentaacetic acid (chelating agent for Eu3+) to a progesterone-protein conjugate. The solid-phase antibody is immobilized inside polystyrene tubes in which plasma samples (50 microL) are assayed directly, without preliminary extraction. After incubation in the presence of trichloroacetic acid, the tubes are washed and the fluorescence intensity of europium is measured by time-wavelength-resolved fluorometry, with a nitrogen laser as the pulsed excitation source. Progesterone values obtained by this procedure agreed well with those obtained by radioimmunoassay (r = 0.98, n = 97). The detection limit was equivalent to that of most RIAs (0.2 micrograms/L).

Adult↗

PubMed1983

Pharmacokinetics of disopyramide in patients with chronic renal failure.

The pharmacokinetics study of a single oral dose of 200 mg of disopyramide was performed in 22 normal control subjects and 33 patients with chronic renal failure (CRF). The latter were subdivided into 3 groups of 11 patients each as a function of the gravity of renal insufficiency. With the exception of maximum concentration (C max), which was only slightly modified, and of the apparent distribution volume which remained unchanged, all the other pharmacokinetic blood parameters (t max, concentration at 24th hour, elimination constant (ke h-1), elimination half-life, area under the curve and plasma clearance) were significantly modified in the CRF group; in particular, the elimination half-life was significantly increased (for 22 cases of CRF with mean plasma creatinine greater than 250 microM at 16.3 hours compared to 8.0 hours in controls). The urinary elimination of disopyramide was studied in 14 renal insufficiency patients and in 6 controls. The decreased rate of urinary excretion of disopyramide and its monodealkylated derivative (NMD), during the first 24 hours, was directly related to the severity of renal insufficiency. The ratio of urinary NMD/(disopyramide + NMD) was unchanged in CRF patients as compared to the controls. The results suggest that the dosage of disopyramide should be decreased when plasma creatinine values are greater than 250 microM, and creatinine clearance is less than 30 ml/min. The dose for a 70 kg subject would be 100 mg, administered every 12 hours.

Adolescent↗

PubMed1982

Comparative immunochemical study of serum and urine proteins in Macaca irus and in humans.

1. A study of serum and urinary proteins of Macaca irus was performed in normal animals in comparison to values normally encountered in humans. 2. Conventional electrophoretic and immunochemical techniques showed that the main variations involved the plasma concentrations of certain proteins, the immunoelectrophoretic profile and the type of haptoglobin. 3. The authors could nevertheless demonstrate the existence of a common antigenicity for a number of proteins.

Animals↗

PubMed1978