DNA topoisomerases I and II in human mature sperm cells: characterization and unique properties.

BACKGROUND: The condensed state of the human sperm's chromatin is essential for the compact structure of the spermatozoon head, which is important for the fertilization process. The enzymes DNA topoisomerases (topo I and topo II) are responsible for the topological structure of the chromatin in somatic cells. The activities and the characterization of topoisomerases in mature human sperm cells have not been previously investigated. METHODS: Sperm cells were purified from the semen of healthy donors by standard procedures and assays measuring the activities, protein size and sensitivity to inhibitors of topoisomerases were performed. RESULTS: Topo I and topo II DNA relaxation activities are present in nuclear extracts derived from human sperm. The sperm topo I activity is inhibited by camptothecin, similarly to the somatic enzyme. An 85 kDa sperm protein, compared with the 100 kDa somatic topo IB enzyme, reacted with anti-human topo I antibody. Sperm topo II lacks the DNA decatenation activity of the somatic enzyme and a 97 kDa protein, compared with the 170 kDa somatic topo IIalpha enzyme, was detected with anti-human topo II antibody. Sperm nuclear extracts contained inhibitors of somatic topo II decatenation activity. CONCLUSIONS: Topoisomerase I and II activities as well as topo I and topo II proteins are present in mature human sperm cells. These enzymes possess unique properties compared with their somatic counterparts.

Monozygotic twins following blastocyst transfer: a report of two cases.

Several studies have shown an increased risk for monozygotic twinning after fertilization treatments. We present the clinical and sonographic characteristics of two monozygotic twin cases following blastocyst transfer. It is suggested that delayed transfer of the embryo in the blastocyst stage is a contributing factor to monozygotic twinning.

Does transcervical intra-fallopian insemination improve pregnancy rates in cases of oligoteratoasthenozoospermia? A prospective, randomized study.

The relatively low pregnancy rates (PR) after treatment of patients with oligoteratoasthenozoospermia (OTA) result in a search for different treatment modalities. The objective of this study was to assess the efficacy of transcervical intrafallopian insemination (IFI) with husband's semen in comparison to intrauterine insemination (IUI) in couples with OTA. A prospective, randomized study included 30 couples with OTA-related infertility (according to WHO criteria). The female patients underwent individually adjusted controlled ovarian stimulation by gonadotropins. Spermatozoa was prepared using the Percoll 70% technique and insemination was performed 36-40 h after human chorionic gonadotropin (HCG) administration. The Tomcat Catheter was used for IUI and the Jansen-Anderson Catheter for IFI to the fallopian tube leading to the ovary that contained more dominant follicles. The couples were divided according to sperm count, into group A (9 couples): < 10 mill ml-1 and group B (21 couples): > 10 mill ml-1. Within the groups the patients were randomly assigned for IUI or IFI treatment. Among group B couples, two pregnancies out of 15 IUI cycles (13.3% PR) and two pregnancies out of 18 IFI cycles (11.1% PR) were achieved. Group A patients completed 7 IUI and 9 IFI treatment cycles with no pregnancies observed. These data did not demonstrate a statistically significant advantage for either technique.

The relationship between endogenous oestradiol and vitamin D3 metabolites in serum and follicular fluid during ovarian stimulation for in-vitro fertilization and embryo transfer.

The present study was undertaken to examine the effect of circulating oestradiol on serum levels of 25-hydroxyvitamin D3 (25-OHD3), 24,25-dihydroxyvitamin D3[24,25-(OH)2D3], and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] during gonadotrophin-induced ovarian stimulation in 10 healthy women undergoing in-vitro fertilization and embryo transfer (IVF). The presence of these metabolites in the follicular fluid was also investigated. Plasma oestradiol increased from 25 +/- 3.2 (mean +/- SE) pg/ml before initiation of treatment to 2563 +/- 328 pg/ml on the day of injection of human chorionic gonadotrophin (HCG) and 1641 +/- 299 pg/ml on the day of ovum retrieval (P < 0.01). Serum levels of 1,25-(OH)2D3 increased from 32.0 +/- 1.9 (mean +/- SE) pg/ml to 46.6 +/- 8.1 and 48.5 +/- 7.7 pg/ml (P < 0.05) on the day of HCG and ovum retrieval, respectively. No changes in blood levels of 25-OHD3 and 24,25-(OH)2D3 were found. The presence of vitamin D metabolites in follicular fluid is documented herein for the first time. All three metabolites were present in the follicular fluid but were significantly lower than in the concurrent serum (P < 0.01). A highly significant correlation was found between serum and follicular fluid levels: r = 0.787, P < 0.001 for 1,25-(OH)2D3; r = 0.738, P < 0.01 for 25-OHD3; and r = 0.751, P < 0.01 for 24,25-(OH)2D3. Our results suggest that raised levels of circulating oestradiol during gonadotrophin-induced ovarian stimulation are associated with a significant increase of serum 1,25-(OH)2D3.