Biomedical subjects

M Hatsuta

Publications and source records attributed to M Hatsuta.

3 recordsLinked to original sources

PubMed2001

Virtual reality system using force feedback device for molecular modeling.

We designed two new concept of computer aided molecular modeling system using virtual reality technologies. Although it is still a prototype, the most characteristic function of the system is enabling its user to "touch" and feel the electrostatic potential field of a protein or a drug molecule. User can scan surface of a protein using a globular probe, which is given an electrostatic charge, controlled by a force feedback devise. The electrostatic force between the protein and the probe is calculated in real time, and immediately fed back into the force feedback device. The user can easily search interactively for positions where the probe is strongly attracted to the force field. Such positions can be regarded as candidate sites where small chemical groups corresponding to the probe, functional parts of lead compounds, can bind to the target protein. We also developed a binding simulator which we can bind a small molecule (drug) to a large molecule (protein). In this system, we placed a camera, so that we can not only "feel" but also "see" how drug fits into the binding site. Our prototype system has the potential to serve as a new application method as well as being applicable to conventional VR technologies, especially to force feedback technologies.

Computer Simulation↗

PubMed1998

Inhibitory regulation of inhibin gene expression by thyroid hormone during ovarian development in immature rats.

To explore the role of the thyroid gland in ovarian development during the initiation process of puberty, we examined the effects of hypothyroidism on the secretion of ovarian hormones during equine chorionic gonadotropin (eCG)-induced follicle development in immature female rats. Immature rats at 22 days of age were thyroidectomized (Tx) to cause hypothyroidism and then given a single s.c. injection of 5 IU eCG at 26 days of age to induce normal first ovulation. The blood samples were collected at 0, 24, and 48 h after eCG treatment to measure inhibin and estradiol by radioimmunoassay. Serum inhibin and estradiol levels in eCG-primed Tx animals were significantly higher at 24 and 48 h after eCG treatment than those in controls (eCG treated non-Tx rats). The number of healthy follicles larger than 400 microns in diameter and ovarian weight were significantly increased in Tx rats at 48 h after eCG treatment, compared to those in controls. The number of oocytes which are ovulated by an injection of human chorionic gonadotropin (10 IU) was significantly increased on the day after eCG treatment, compared to that of eCG treated non-Tx rats. The increments in both hormones levels, the number of large antral follicles, and ovarian weight in eCG-primed Tx animals were suppressed up to control levels with daily administrations of 5.0 micrograms thyroxine (T4) for 6 days during 22 to 27 days of age. The expression of mRNAs for inhibin alpha and beta A subunits increased in eCG-primed Tx rats at 48 hr after eCG treatment, and the increase in inhibin mRNAs was suppressed by T4 treatment up to control levels. These results clearly demonstrate that thyroid hormone takes part in an inhibitory regulation of ovarian hormonal secretion and folliculogenesis in eCG-primed immature female rats.

Animals↗

PubMed1998

Blockage of gonadotropin-induced first ovulation caused by thyroidectomy and its possible mechanisms in rats.

To determine the role of the thyroid gland on the ovarian functions during the initiation process of puberty, we examined the effects and its mechanisms of hypothyroidism on the first ovulation induced by equine chorionic gonadotropin (eCG) in immature female rats. Animals were thyroidectomized on day 22 and were injected with 5 IU of eCG on day 26 to induce the first ovulation on day 29. The number of antral follicles that secrete inhibin and the ovarian weight were significantly increased in thyroidectomized rats (Tx rats) 48 h after eCG treatment compared with those in non-Tx rats. However, thyroidectomy (Tx) significantly suppressed the rates of ovulating animals on day 29. The blockage of ovulation in Tx rats was recovered by administration of human chorionic gonadotropin or luteinizing hormone (LH)-releasing hormone (LHRH) on day 28. Inhibition of serum LH (not follicle-stimulating hormone) levels induced by Tx was almost restored to control levels by injection of LHRH. A significant increment in prolactin levels in Tx rats was also observed on day 28. The present data indicate that Tx before puberty in female rats causes the blockage of the first ovulation and that the inhibitory effects on ovulation are mainly due to the reduction in the preovulatory LH surge, which is partially mediated through an inhibition of LHRH action on the secretion of LH.

Animals↗