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Biomedical subjects

M Hiroi

Publications and source records attributed to M Hiroi.

At least 181 records · Page 10Linked to original sources
PubMed1978

[Effects of several estrogenic compounds on serum corticosteroid-binding globulin (CBG) and the estrogen thresholds for increasing CBG (author's transl)].

The effects of several estrogen substances--alone, or in combination with norgestrel--on serum CBG in humans are reported in this paper. CBG was measured by a modified charcoal adsorption technique. Daily oral doses of Premarin, from 0.3 to 2.5mg, were given to healthy postmenopausal women for 14 days. Dose-dependent increases in CBG-BC were observed. Ovral, which contains ethinylestradiol and norgestrel, also induced significant increases in the levels of CBG-BC. Similar results were seen with Lo Ovral, but it had less influence than Ovral. When given alone, daily for 21 days, norgestrel had no effect on CBG-BC. The maximum rise of serum CBG-BC was found after 10 days of the daily doses of Ovral, and then the levels remained quite constant during the period of treatment. Exogenous estrogens of other types also caused increases in CBG-BC. The response of CBG to exogenous estrogens is of use in comparing the estrogen potencies of the compounds. CBG-BC levels remained constant throughout the menstrual cycle in five normal women despite fluctuating levels of estradiol which reached peaks of 190 approximately 430 pg/ml. In pregnant women and in HMG-treated women, however, serum levels of CBG-BC increased beginning when estradiol levels were greater than 1 ng/ml.

Adult↗
PubMed1978

[A double adsorption technique for the determination of corticosteroid-binding globulin in human serum (author's transl)].

Despite the widespread use of many different estrogenic compounds in hormonal contraception and estrogen replacement, in the human a simple test for comparing the potencies of the compounds is lacking. Many of the estrogenic compounds are difficult to measure, and animal studies may not relate directly to those done on humans in terms of potency. Corticosteroid-binding globulin (CBG) in human serum has been known since 1958 to increase in response to estrogen administration, and the degree of its elevation has been shown to be closely dose-related and reasonably sensitive. Therefore, CBG represents a biological parameter that provides for the specific quantal analysis of estrogenicity in the human. In this paper a simple and reliable method for the determination of the cortisol-binding capacity of CBG (CBG-BC) in human serum is described. The procedure is based on the amount of cortisol required to saturate the CBG binding sites. All endogenous steroids are initially removed from the serum by adsorption on dextran-coated charcoal (DCC). A mixture of a known amount of unlabeled and labeled cortisol is added to the sample in order to saturate the "stripped" binding sites of CBG. The unbound cortisol is removed by DCC at 4 degrees C, and the supernatant represents the total cortisol-binding capacity of the serum sample. To distinguish between cortisol-binding to CBG and to albumin, "stripped" serum is heated for 30 min at 60 degrees C, the temperature which does not influence cortisol binding by albumin but which does inactivate CBG. The samples are subsequently equilibrated with a mixture of labeled and unlabeled cortisol. The free cortisol is removed by DCC and the bound cortisol remaining in the supernatant is designated as the albumin-bound cortisol. Thus, CBG-BC is assayed by a double adsorption technique as differential binding to native and heat-inactivated serum. The cortisol determined by this method corresponds to CBG-bound cortisol, and CBG-BC is expressed as micrograms of cortisol bound per 100 ml serum. The precision and accuracy of the method were found to be good. The values of CBG-BC obtained by this method were 14.9 +/- 1.9 (SD) microgram/100ml in adult men and 16.0 +/- 1.8 microgram/100ml in adult women. Daily serum samples in five women revealed no significant variations in CBG-BC throughout the normal menstrual cycle despite fluctuating levels of serum estradiol. CBG-BC was also found not to vary significantly with age. In pregnancy, however CBG-BC increased significantly.

Adsorption↗
PubMed1975

Radioimmunoassay of serum medroxyprogesterone acetate (Provera) in women following oral and intravaginal administration.

A radioimmunoassay (RIA) method for measuring medroxyprogesterone acetate (MPA, Provera) in serum has been developed utilizing benzene:iso-octane extraction, 3H-MPA to assess procedural losses, goat anti-MPA-3-(0-carboxymethyl) oxime-bovine serum albumin serum and dextran-coated charcoal separation. Control serum blanks were undetectable, 200 pg/ml of MPA was measurable with a high reliability, and intra- and interassay coefficients of variation were 6 and 13 percent, respectively. MPA added to control serum was quantitatively recovered. Serum MPA levels measured in 2 women after ingestion of 10 mg MPA rose to 3.4 to 4.4 ng/ml within 1 to 4 hours after oral intake and fell rapidly thereafter to 0.3 to 0.6 ng/ml within 24 hours. Insertion of Silastic intra-vaginal rings (IVRs), containing 100 or 200 mg of MPA, into 4 women for periods of 3 weeks resulted in a rapid rise of serum MPA after insertion, rather stable MPA levels of 0.9 to 1.6 ng/ml while the IVRs were in place, and a rapid decline of serum MPA following IVR removal. Serum estradiol-17beta and progesterone concentrations, measured about 3 times a week in these patients, indicated that ovulation was consistently inhibited. The serum MPA levels observed in this study were approximately 5 times lower than those reported by other investigators using a double-antibody RIA of MPA in unextracted serum.

Administration, Oral↗