Molecular dissection of an hCG-beta epitope using single-step solid phase radioimmunoassay.

BACKGROUND: Peptides and proteins have both sequence-specific (contiguous) and conformation-specific (discontiguous) epitopes. Sequence-specific epitopes are delineated by peptide approach and other robust methods like competition assays, gene expression assays, synthetic peptide library based assays etc. Available methods for delineation of conformation-specific epitopes are cumbersome (X-ray crystallography etc.), time-consuming and require costly sophisticated equipments. Hence, there is a need to develop a simple method for identification and mapping of conformation-specific epitopes. METHOD: In the single-step solid phase radioimmunoassay (SS-SPRIA), an immunochemical bridge of 'mouse IgG-anti-mouse IgG' was prepared in the polypropylene wells followed by adsorption with hCG specific monoclonal antibody (MAb) G(1)G(10).1. The extent of competitive inhibition in binding ability of (125)IhCG-beta with chemically or enzymatically modified hCG-beta to immobilized MAb G(1)G(10).1 in comparison to hCG-beta standards was utilized to identify the epitopic amino acid involved in epitope-paratope interaction. RESULTS: Data clearly suggest that the epitope under investigation consisted of Arg (94, 95) and Asp (99) at the core region with a Lys (104) and a His (106) in the proximity and absence of chymotrypsin susceptible Phe or Tyr in this region. CONCLUSION: The data of SS-SPRIA revealed the 93-100 loop of amino acid sequence, as the core region of conformation-specific epitope of hCG-beta at or near the receptor-binding region. Hence, SS-SPRIA seems to be a simple method for identification and mapping of conformation-specific epitopes.

Enzyme immunoassay of cortisol in human plasma using penicillinase as label.

An enzyme immunoassay for cortisol in human plasma using an antiserum raised against cortisol-3-O-carboxy-methyloxime bovine serum albumin and cortisol-21-hemisuccinate conjugated to penicillinase as tracer is described. Although employing immunoassay plates for separation of antigen-antibody complex from the free components was less time consuming, the slope and sensitivity of the standard curve were improved by the addition of goat anti-rabbit gamma globulin for precipitating the complex. There was good correlation between radioimmunoassay and enzyme immunoassay results obtained for cortisol levels present in normal human plasma.

Enzyme immunosorbant assay of oestradiol in unextracted plasma using penicillinase as label.

An enzyme-linked immunosorbant assay (ELISA) for measuring oestradiol directly in plasma without extraction utilizing antibodies raised against oestradiol-3-(O-carboxymethyl) ether-bovine serum albumin conjugate, and oestradiol-6-(O-carboxymethyl) oxime linked to penicillinase (EC 3.5.2.6) as a marker was developed. Polyvinyl 96-well microtitre plates were used for immobilization of anti-oestradiol IgG. Standards of oestradiol (92 to 9,190 pmol/l were prepared in oestradiol-free plasma and 8-anilino-1-naphthalene sulphonic acid (8-ANS, 5 mg/ml of 10 mmol/l PBS) was added to the microtitre plate wells to displace oestradiol from plasma binding proteins. The assay had a lower limit of detection of 92 pmol/l plasma and could be performed within 4 h. Comparison of oestradiol values of 51 plasma specimens obtained by ELISA with those of radioimmunoassay (RIA), in which oestradiol was extracted with diethyl ether, showed good correlation (y = 0.786x + 0.03; r = 0.900).

Hormonal control of implantation in guinea pigs.

In the guinea pig, for which implantation is supposedly progesterone-dependent, actual hormonal requirements were assessed by measuring the levels of circulating estradiol and progesterone and correlating them with their content in the ovaries and uterus, and uterine concentrations of their receptors prior to, during, and immediately after implantation. Ovarian and uterine content and plasma levels of estradiol and progesterone, as well as uterine cytosolic receptors of these two hormones, were high at proestrus. Up to day 3 of pregnancy, estradiol remained high in peripheral plasma, ovarian and uterine tissues, but reached low levels at the time of implantation. The levels of progesterone showed a gradual increase in plasma and ovaries till the time of implantation, with the embryonic site of the uterus accumulating more of progesterone compared to estradiol. As pregnancy progressed, a gradual translocation of cytosolic to nuclear receptors occurred, both with estradiol and progesterone receptors. Comparing the receptor values for estradiol at each uterine site showed no significant alterations between embryonic and interembryonic cytosolic receptors. While significantly high levels of nuclear estradiol receptor were found at the inter-embryonic site on day 9 of pregnancy, the cytosolic and nuclear progesterone receptor concentrations were greater at the embryonic site on the same day. These findings demonstrated that the uterus is adequately exposed to estradiol and progesterone prior to ovulation and again in early pregnancy (day 1-3), thus facilitating implantation in the guinea pig (on days 7-8).

Influence of different combinations of antibodies and penicillinase-labeled testosterone derivatives on sensitivity and specificity of immunoassays.

Three antisera raised against bovine serum albumin (BSA) conjugates of testosterone-3-(O-carboxy-methyl)-oxime (T-3-CMO), 11 beta-hydroxytestosterone-11-carboxymethyl ether (T-11 beta-O-CME) and 19-hydroxytestosterone-19-carboxymethyl-ether (T-19-O-CME) were evaluated in enzyme immunoassays (EIAs) in combinations with penicillinase-labeled T-3-CMO, T-11 beta-O-CME, T-19-O-CME, and testosterone-17 beta-hemisuccinate (T-17 beta-HS) for their influence on the sensitivity and specificity of EIAs. Of the various combinations, anti-T-3-CMO antiserum along with T-11 beta-O-CME-penicillinase showed no cross-reaction with any of the closely related steroids, although the same antibody had 21.6% binding to 5 alpha-dihydrotestosterone (5 alpha-DHT) in radioimmunoassay. All the homologous combinations appeared to be less sensitive due to their low affinity for testosterone. It was also apparent that of all the heterologous systems tested, only two combinations, (a) anti-T-19-O-CME antiserum and T-3-CMO-penicillinase and (b) anti-T-3-CMO antiserum and T-11 beta-O-CME-penicillinase, were found to be more sensitive. The former was less specific; it showed 70% cross-reaction with 5 alpha-DHT. The ability of testosterone to displace the hapten-enzyme conjugate and the specificity of the assay appear to depend on the position of the enzyme label on the steroid molecule as well as on the availability of antigenic sites in particular combinations of antibody and hapten-enzyme conjugates.

Application of seminal germ cell morphology and semen biochemistry in the diagnosis and management of azoospermic subjects.

AIM: To evaluate whether the study of seminal germ cell morphology (SGCM) and semen biochemistry could be fruitfully utilized for the diagnosis and management of azoospermic subjects. METHODS: In the semen, mature and immature germ cells are contributed by the testes, 70% of glycerylphosphoryl choline (GPC) by the epididymis, fructose mostly or solely by the seminal vesicles and acid phosphatase [corrected] (ACP) by the prostate. In 16 normal volunteers, 12 vasectomized subjects and 186 azoospermic subjects, these parameters have been studied and the data have been analyzed. RESULTS: Both mature and immature germ cells are absent in the semen of vasectomized subjects as well as in obstructive azoospermia; GPC level is also significantly decreased in both these groups. In cases with non-obstructive azoospermia immature germ cells are present and seminal GPC, ACP and fructose levels are normal. The diagnosis of obstructive and non-obstructive azoospermia based on these parameters correlated well with "correct" testicular biopsy findings. In some cases of azoospermia due to hypospermatogenesis or spermatogenic developmental arrest, the SGCM studies were very helpful in objectively monitoring the response of the germinal tissue to specific treatments. CONCLUSION: SGCM and semen biochemical parameters are very valuable non-invasive markers for differentiating obstructive from non-obstructive azoospermia. The SGCM findings serve as a dependable non-invasive testicular marker with high predictive value.

Urinary steroid hormone patterns: III. Effect of continuous daily administration of low dose megestrol acetate.

PIP: The effect of megestrol acetate, administered in daily doses of .5 mg, on urinary steroid levels was studied before, during, and after therapy in 4 women volunteers. In each case, pregnanediol levels were reduced, though ovulatory biphasic patterns, as reflected in basal body temperature patterns, were apparent in the majority of the cycles, which suggests that corpus luteum function, but not ovulation, was impaired. 17-ketosteroid levels were significantly (p less than .001) increased either during or after treatment, while 17-hydroxycorticoid levels were reduced in 3 of the women. 2 subjects showed a marked reduction in levels of 17-ketogenic steroids and corticoid levels. Total estrogen levels seemed to correlate with the levels of corticoid excretion.^ieng

Effect of synthetic progestins on the uptake of labelled testosterone and estradiol-17beta by the accessory genital organs of male rats.

PIP: The effect of pretreatment with norethindrone (NE) or 17-hydroxyprogesterone caproate (17-OHPC) on the uptake of tritiated testosterone and estradiol-17beta by the accessory sex organs of castrated and intact rats was investigated. A selective in vivo increase in the incorporation of tritiated testosterone and estradiol-17beta was observed at 48 hours after castration. The uptake of testosterone was greatest in the epididymis, while the maximum incorporation of estradiol-17beta was by the vas deferens. Pretreatment with NE or 17-OHPC decreased the incorporation of testosterone by all the accessory organs of castrated rats. NE decreased the incorporation of tritiated estradiol-17beta in the epididymis and seminal vesicles only, while 17-OHPC decreased the uptake in all accessory organs.^ieng

Effect of Centchroman administration in normospermic & oligospermic individuals.

PIP: The effect of Centchroman, 3,4-trans-2,2-dimethyl-3-phenyl-4-para-(beta -pyrrolidinoethocy)-phenyl-7-methorychroman, administration was investigated in normospermic and oligospermic subjects. 3 normal volunteers, aged 32-40 years, were treated with increasing doses (30, 60, and 120 mg/day, each dose for 2 weeks). The sperm count was decreased in 1 volunteer but the percentages of nonmotile and abnormal spermatozoa were increased in all 3. There was no change in plasma testosterone and urinary 17-ketosteroid (17-KS) levels but the 17-ketogenic steroids (17-KGSs) were decreased in all of them. 3 out of 5 oligospermic subjects, aged 24-35 years, who received 30 mg/day for 6 weeks revealed increased sperm counts. Plasma testosterone levels were decreased in 4, urinary 17-KGSs were decreased in 2, and 17-KSs were decreased in 1 subject. Acid phosphatase, fructose, sialic acid and glycerylphosphoryl choline levels in semen, and serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, alkaline phosphatase, and urea in blood were not markedly altered in either group.^ieng