Biomedical subjects

Koji Ozaki

Publications and source records attributed to Koji Ozaki.

3 recordsLinked to original sources

PubMed2006

Insulin-lowering agents inhibit synthesis of testosterone in ovaries of DHEA-induced PCOS rats.

BACKGROUND: Insulin-lowering agents are reported to be useful in treating polycystic ovary syndrome (PCOS) anovulation. It has been suggested that lower insulin levels secondarily affect ovarian tissue, although the direct mechanism of action has not yet been verified. Here we investigated if these agents directly affect the ovary. METHODS: Thirty female Wister rats were studied. Six control rats were injected subcutaneously with 0.2 ml sesame oil, while 24 rats used as PCOS models were injected subcutaneously with dehydroepiandrosterone (DHEA) and divided into four groups. Six rats were injected with only DHEA, while the remaining 18 rats received metformin, pioglitazone or troglitazone. The ovaries were immunohistochemically stained with anti- testosterone and anti-17beta-HSD antibodies, and then evaluated for morphological changes. RESULTS: In the DHEA administration group, the number of atretic follicles significantly increased compared to that of control rats. The insulin-lowering agents did not improve the multicystic appearance. Serum testosterone concentrations significantly increased with DHEA administration, but the increase was inhibited by oral administration of insulin-lowering agents. Testosterone deposits in ovarian tissue were also reduced by feeding rats insulin-lowering agents. CONCLUSION: Insulin-lowering agents affected ovarian tissue by inhibiting testosterone biosynthesis in vivo.

17-Hydroxysteroid Dehydrogenases↗

PubMed2003

Using a vortex mixer for testicular sperm collection.

OBJECTIVE: To evaluate 2 methods of processing testicular tissue for the retrieval of viable sperm from men with nonobstructive azoospermia. STUDY DESIGN: Fresh testicular tissue was obtained from nonobstructive azoospermia patients using a biopsy needle. The specimens were divided into 2 fractions. All specimens were minced and immersed in human tubal fluid (HTF). The first fraction was filtered through a nylon filter and incubated for 3 hours. The supernatant was centrifuged, resuspended in HTF and analyzed. The second fraction was immediately vortexed for 5 minutes and filtered through a nylon filter. The supernatant was centrifuged, resuspended in HTF and analyzed. RESULTS: Spermatozoa were obtained in 13 of 24 cases (54.2%) using the vortex method and in 5 of 24 cases (20.8%) with the nylon filter method. CONCLUSION: The vortex mixing method may be a better option than the conventional method for processing testicular tissue for sperm collection.

Adult↗

PubMed2003

Expression and distribution of cyclooxygenase-2 in human ovary during follicular development.

Prostaglandins play important roles for oocyte maturation and follicular rupture. Cyclooxygenase-2 (COX-2), an inducible isoform of a prostaglandin metabolic enzyme, is essential for the timed production of prostaglandins in the ovary. The aim of the present study is to examine expression and distribution of COX-2 in human ovarian follicles at each of the maturation stages. Immunohistochemical staining shows that COX-2 is expressed in the granulosa cell layer of secondary and developing follicles, but is not detected in primary and Graafian follicles. Western blotting analysis revealed the existence of COX-2 in periovulatory follicular fluid at a mean concentration of 5.6 +/- 0.6 ng/ml. COX-2 might begin to be produced at the secondary follicle stage, and once a follicle reaches the Graafian follicle stage, the production of this enzyme is stopped. After exposure to luteinizing hormone (LH) surge, follicles might resume production of COX-2, and this is secreted into the follicular fluid.

Adult↗