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Tapio Hase - One of the best experts on this subject based on the ideXlab platform.

Tapio Mäkelä - One of the best experts on this subject based on the ideXlab platform.

Jorma Matikainen - One of the best experts on this subject based on the ideXlab platform.

Kiran K Soma - One of the best experts on this subject based on the ideXlab platform.

  • analysis of steroids in songbird plasma and brain by coupling solid phase extraction to radioimmunoassay
    General and Comparative Endocrinology, 2008
    Co-Authors: Amy E M Newman, Eunice H Chin, Kim L Schmidt, L Bond, Katherine E Wynneedwards, Kiran K Soma
    Abstract:

    It is a common practice to extract steroids from plasma, serum, or tissue samples prior to steroid measurement by radioimmunoassay (Ria) or enzyme immunoassay (EIA). Steroid extraction is critical because it can remove substances that interfere with the Ria or EIA. Steroid extraction is commonly achieved using organic solvents, such as diethyl ether or dichloromethane. However, organic solvent extractions can suffer from low recovery, imprecise recovery, or incomplete removal of assay interference. Here, we describe validations of a simple protocol to extract steroids (e.g., dehydroepiandrosterone, corticosterone, and estradiol) from avian plasma, serum, and brain tissue using solid phase extraction (SPE) with commercially available C18 columns. We compare various methods for (1) eluting steroids from columns, (2) drying eluates, and (3) resuspending dried eluates prior to Ria. The SPE method yields high and consistent recoveries. The SPE method also effectively separates steroids from interfering substances, even when extracting steroids from lipid-rich plasma and brain tissue. These data indicate that SPE is superior to organic solvent extraction on several measures. SPE should be broadly useful for extracting steroids from plasma or tissue samples.

Bill L Lasley - One of the best experts on this subject based on the ideXlab platform.

  • relationship of serum estradiol and progesterone concentrations to the excretion profiles of their major urinary metabolites as measured by enzyme immunoassay and radioimmunoassay
    Clinical Chemistry, 1991
    Co-Authors: C J Munro, G H Stabenfeldt, Jeffrey R Cragun, L A Addiego, James W Overstreet, Bill L Lasley
    Abstract:

    Paired daily blood and urine samples were collected from 10 apparently healthy premenopausal women to compare the hormone profiles of estradiol (E2) and progesterone in serum with those of estrone conjugates (E1Conj) and pregnanediol-3-glucuronide (PdG) in urine. Serum hormones were measured by radioimmunoassay (Ria) kits, whereas the urinary steroid metabolites were assessed by both Ria and enzyme immunoassay (EIA). Ria and EIA values for urinary E1Conj and PdG were not different, and both methods produced urinary profiles that paralleled the profile of the parent steroid in serum. However, the simplicity, flexibility, and economy of EIA will make this method more widely applicable. Mean E1Conj values lagged behind concentrations of serum E2 by one day or less, whereas daily urinary PdG profiles lagged behind serum progesterone by one to two days. Mean urinary profiles of E1Conj were similar whether or not creatinine was used to adjust for urine volume; however, creatinine indexing was beneficial when urinary profiles in individual cycles were compared with changes of serum E2.