Systemic bioavailability of ocularly applied 1% atropine eyedrops.

PURPOSE: To investigate the pharmacological basis of systemic effects of atropine eyedrops, we estimated the bioavailability of ophthalmic 1% atropine solution in healthy volunteers. METHODS: In a randomized crossover study we administered 0.3 mg atropine either intravenously or ocularly to six healthy volunteers. The plasma concentrations of the biologically active atropine enantiomer, 1-hyoscyamine, were determined using a muscarinic cholinoceptor binding assay. RESULTS: The mean area under the curve from zero to infinitum (AUC0-infinity) for 1-hyoscyamine was 1.862+/-0.580 microg/L x hr after intravenous, and 1.092+/-0.381 microl/L x hr after ocular administration (mean+/-sd, n=6), respectively. The mean bioavailability was 63.5+/-28.6% (mean+/-SD, n=6; min 19%, max 95%). Large interindividual differences characterized the absorption and elimination phases of 1-hyoscyamine kinetics. The terminal half-life (t1/2beta) of 1-hyoscyamine in plasma was not affected by the route of drug administration. CONCLUSION: The systemic bioavailability of 1-hyoscyamine was considerable and may explain the systemic anticholinergic side effects reported in association with the clinical use of atropine eyedrops.

Steroid receptors and Ki-67 reactivity in ovarian cancer and in normal ovary: correlation with DNA flow cytometry, biochemical receptor assay, and patient survival.

Steroid hormone receptors and reactivity for Ki-67 proliferation antigen were studied immunohistochemically in non-neoplastic post-menopausal human ovary and in 29 ovarian cancers. In the normal ovary, oestrogen (OR) and progesterone receptors (PR) were found in the surface epithelium and PR also in the ovarian stroma. Of the ovarian carcinomas 38 per cent (11/29) contained OR and 69 per cent (20/29) PR. Oestrogen receptor expression was confined to malignant cells, whereas PR was present occasionally also in the tumour stroma. In most cases, ORs and PRs were found only in a small population of cancer cells. The growth fractions assessed by the percentage of Ki-67-positive cells ranged from 1 to 59 per cent (mean 19.7 per cent) with a significant correlation (r = 0.74, P less than 0.0001) to S-phase values (mean 12.9 per cent, range 1.2-25.9 per cent) determined by DNA flow cytometry. High Ki-67 (greater than or equal to 15 per cent) and S-phase levels (greater than or equal to 7.5 per cent) correlated with advanced disease stage and patient survival but not with OR or PR status, suggesting that hormone-receptor pathways and proliferative activity are not related in ovarian cancer. Positive OR status, however, identified patients with a better prognosis (P = 0.02), suggesting a correlation with tumour differentiation. The independent prognostic value of oestrogen receptor status and Ki-67 remains to be determined, but the prognostic impact of Ki-67 was comparable to that of S-phase values.

An immunocytochemical study of the progesterone receptor in rabbit ovary.

Distribution of progesterone receptor (PR) was studied immunohistochemically in rabbit ovary and uterus using a monoclonal anti-receptor antibody. At the subcellular level, PR was located in cell nuclei of prepubertal rabbits, which were either non-treated, primed with estrogen or made pseudopregnant. At the tissue level, germinal epithelium, the external theca cell layer and granulosa cell layer were PR-positive. The internal theca cell layer had no PR immunoreactivity. The corpora lutea of pseudopregnant rabbits contained small amounts of PR in some of the animals. During pseudopregnancy, the distribution and staining intensity of PR-positive cells in the ovary was essentially similar to that in non-treated rabbits except for weak PR immunoreactivity in the internal theca cell layer. This differed significantly from the uterus, in which pseudopregnancy caused a marked decrease in PR immunoreactivity. This implies that receptor downregulation by endogenous progesterone is not the same in different organs and cell types. Immunohistochemical techniques give valuable information as to the steroid hormone target cell types and their distribution which are not available by conventional steroid-binding assays.

Immunocytochemical localization of progesterone receptor in the chick ovary.

The distribution of progesterone receptor (PR) in the chick ovary was studied using light- and electron-microscopic immunocytochemical methods. With the light microscopic technique, PR was observed in the germinal epithelium cells of estrogen-treated and estrogen-untreated immature chicks. With the preembedding immunocytochemical technique, which proved to be more sensitive than immunohistochemistry using paraffin sections, the germinal epithelium and also part of the thecal and stromal cells were stained when immature chicks were not treated with estrogen. After estrogen treatment, the number of PR-positive stromal and thecal cells increased, as did the immunostaining intensity in their nuclei. The granulosa cells were PR-positive only after estrogen treatment. In the ovary of laying hens, the most intense staining for PR was localized in the germinal epithelium. PR was also present in the thecal, stromal, and granulosa cells. At the subcellular level, PR was detected only in the cell nuclei, indicating that ovarian PR is intranuclear independent of the presence of progesterone. In conclusion, immunocytochemical methods proved to be suitable for studying steroid hormone receptors in steroid-producing tissues (e.g. the ovary), because excess endogenous hormones do not affect detection of the receptor with the antibody as they do detection with labeled ligands. Immunocytochemically, the germinal epithelium, stromal, thecal, and granulosa cells of the laying hen ovary were shown to be target cells for progesterone. The inducibility of PR by estrogen in the thecal, stromal, and granulosa cells suggests that these cell types are also sensitive to estrogen.