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Masahito Tachibana

Publications and source records attributed to Masahito Tachibana.

5 recordsLinked to original sources
PubMed2006

Successful strategy for the hysteroscopic myomectomy of a submucous myoma arising from the uterine fundus.

OBJECTIVE: To introduce a technique for hysteroscopic resection of submucous myoma arising from the uterine fundus. DESIGN: Case report. SETTING: University hospital. PATIENT(S): A 43-year-old nulliparous Japanese woman. INTERVENTION(S): An original combination technique of hysteroresectoscopy using circumferential myoma scraping, central vaporization, and intraoperative injection of prostaglandin F2alpha. MAIN OUTCOME MEASURE(S): Evaluation of clinical symptoms and imaging diagnosis. RESULT(S): Resection of a 40-mm fundal myoma was performed hysteroscopically, and the menorrhagia of the patient was remedied by the operation. CONCLUSION(S): Although large sessile fundal myomas are difficult to resect by hysteroscopic myomectomy, our original strategy may allow safe and certain surgery in such cases.

Adult↗
PubMed2005

A trial to restore defective human sperm centrosomal function.

BACKGROUND: In human fertilization, sperm centrosome function is essential for male and female pronuclear movement and fusion. In this study, we investigated the possibility of restoring human sperm centrosomal function in sperm exhibiting abnormalities in microtubule organization. METHODS: Semen was obtained from both a fertile donor and a patient with dysplasia of the fibrous sheath (DFS). Following heterologous ICSI using human sperm, we examined microtubules and chromatin configuration in bovine oocytes. Sperm were treated with dithiothreitol (DTT) prior to ICSI, while the oocytes were treated with the cytoskeletal stabilizer paclitaxel after ICSI. RESULTS: The combination of DTT and paclitaxel treatment induced microtubule organization in dead sperm from the fertile donor following heterologous ICSI. This treatment, however, was not effective for DFS sperm. In addition, expression of centrin, a protein functioning within the sperm centrosome, was reduced in DFS sperm from that of the normal levels observed in fertile donor sperm. CONCLUSION: These results indicate that sperm centrosomal function could be induced by the treatment of sperm with DTT before ICSI and of oocytes with paclitaxel after ICSI. DFS sperm are likely to exhibit such severe dysfunction of sperm centrosome that cannot be compensated for by this treatment; therefore, this method may be a practical way to discern the degree of sperm centrosomal dysfunction.

Adult↗
PubMed2005

Dynamic changes in the cytoskeleton during human spermiogenesis.

OBJECTIVE: To investigate the structural changes in the cytoskeleton (microtubules, microfilaments) and examine the expression of centrosomal functional proteins during human spermiogenesis. DESIGN: Immunofluorescent staining of human spermiogenic cells. SETTING: University hospital and IVF clinic. PATIENT(S): Human testicular tissues were obtained by testicular sperm aspiration (TESA) under informed consent. Three cases of obstructive azoospermia, with confirmed normal spermatogenesis, were examined. INTERVENTION(S): Spermatogenic cells were fixed with microtubule-stabilizing buffer. Immunocytochemical detection of microtubules, microfilaments, and centrosome was performed using monoclonal antibodies against alpha- and beta-tubulin, phalloidin, and functional centrosomal proteins. MAIN OUTCOME MEASURE(S): Samples were examined using epifluorescence and laser scanning confocal microscopes. RESULT(S): During the Sb2 period, microtubules formed the manchette structure, which extended from the equator of the nucleus through the cytoplasm. Microfilaments were organized in the periacrosamal region during spermiogenesis (Sa to Sd). Although centrin was observed throughout the spermiogenic period, gamma-tubulin was detected only in the Sb2 period. CONCLUSION(S): Dynamic cytoskeletal movement was observed during human spermiogenesis. Cytoskeletal rearrangements in the Sb2 period appear to play important roles in the morphologic changes that occur during human spermiogenesis. Studies of the cytoskeletal system during spermiogenesis may help identify some causes of male infertility (e.g., teratozoospermia, maturation arrest).

Adult↗
PubMed2004

Use of Mammalian eggs for assessment of human sperm function: molecular and cellular analyses of fertilization by intracytoplasmic sperm injection.

PROBLEMS: Intracytoplasmic sperm injection (ICSI ) has been described as the 'cure' for male sterility because a single sperm can now be directly introduced into an egg with some chance of pregnancy. While ICSI has revolutionized the practice of assisted reproductive techniques (ART), there are few molecular and cellular studies about its safety and efficacy. Even by using ICSI, fertilization in humans succeeds only if the sperm effectively accomplishes a number of tasks including 'post-ICSI events' in fertilization. To assess the function of human sperm after ICSI, we used heterologous ICSI with human sperm into animal eggs. Egg activation, sperm decondensation and sperm centorosomal function were examined in sperm from fertile men and infertile patients. METHODS: Sperm from fertile men and infertile patients were injected into hamster, rabbit and bovine eggs by Piezo micromanipulator, and studied in decondensation of sperm nuclei, egg activation and microtubule organization. RESULTS: Decondensation human sperm head following ICSI into hamster eggs occurred initially form basal lesion, and apical portion of sperm nuclei which is surrounded by acrosome and perinuclear theca, still condensed in early pronuclear stage. Radial array of microtubules from sperm centrosome 'sperm aster' which is essential for pronuclear movement was observed in 30% rabbit eggs following ICSI with human sperm. By heterologous ICSI system with fertile human sperm and bovine eggs, 83.3% of eggs was activated and 60% eggs had sperm aster, indicating that bovine Piezo ICSI system is appropriate for assessing human sperm oocyte activation ability and human sperm centrosomal function. Oocyte activation and sperm centrosomal function were significantly low in sperm from men with globozoospermia and men with dysplasia of fibrous sheath. CONCLUSION: These assays indicate differences of the process of fertilization between in vitro fertilization and ICSI, and reflect the human sperm function especially for the 'post-ICSI events' in fertilization. More molecular and cellular analyses in fertilization by ICSI are needed for improvement of ART.

Acrosome↗