Biomedical subjects

Tatsuya Sugita

Publications and source records attributed to Tatsuya Sugita.

4 recordsLinked to original sources

PubMed2006

Aberration properties in a chirped grating for coarse wavelength division demultiplexing.

We studied the imaging performance of a chirped grating for a demultiplexer designed for coarse wavelength division multiplexing using a wavefront aberration analysis and the ray tracing simulation. The demultiplexer was composed of a chirped grating, cylindrical lenses, and a waveguide. The best image point and the spot shape focused by the chirped grating were effectively calculated with the wavefront aberration. We applied the aberration analysis to design a waveguide to connect branched beams to photodetectors, and we confirmed the demultiplexing performance experimentally.

Journal Article↗

PubMed2006

Ovarian hyperstimulation caused by gonadotroph cell adenoma: a case report and review of the literature.

OBJECTIVE: We present a case of spontaneous ovarian hyperstimulation caused by pituitary gonadotroph macroadenoma, and include a review of the literature. CASE REPORT: A 27-year-old woman presented with irregular menstruation and bilateral multicystic enlargement of the ovaries. Serum estradiol (E(2)) levels were marginally elevated for the follicular phase but within the physiological range. Serum luteinizing hormone (LH) was extremely low, follicle-stimulating hormone (FSH) was normal, and prolactin (PRL) was high. Magnetic resonance imaging disclosed a pituitary macroadenoma. Immunohistochemical examination of the surgically removed adenoma showed intense reactivity for FSH and LH. After the operation, E(2), LH and PRL levels were normalized, the ovaries returned to a normal morphology, and regular menstrual cycles were resumed. CONCLUSION: A review of the literature showed that ovarian hyperstimulation caused by pituitary gonadotroph adenoma is not always accompanied by elevated FSH levels. High PRL and E(2) and low LH were reported in the majority of the cases, but E(2) may stay within the range observed in normal menstrual cycles.

Adenoma↗

PubMed2005

Bidirectional optical coupler for plastic optical fibers.

We have developed a low-loss bidirectional optical coupler for high-speed optical communication with plastic optical fibers (POFs). The coupler, which is fabricated by an injection molding method that uses poly (methyl methacrylate), has an antisymmetric tapered shape. We show that the coupler has low insertion and branching losses. The tapered shape of the receiving branch reduces beam diameter and increases detection efficiency coupling to a photodetector, whose area is smaller than that of the plastic optical fiber. The possibility of more than 15-m bidirectional transmission with a signaling bit rate up to 500 Mbits/s for simplex step-index POFs is demonstrated.

Journal Article↗

PubMed2005

Successful pregnancy and delivery after removal of gonadotrope adenoma secreting follicle-stimulating hormone in a 29-year-old amenorrheic woman.

We report a case of ovarian hyperstimulation related to a gonadotroph adenoma in a 29-year-old woman. The patient presented with amenorrhea and large cystic ovaries. Her serum estradiol was markedly elevated (up to 31,100 pmol/l). Serum LH was low, but serum FSH and PRL were normal. Cranial magnetic resonance imaging study revealed a pituitary macroadenoma. After successful removal of the pituitary tumor, FSH, LH and estradiol normalized and fluctuated within normal ranges thereafter. The patient resumed regular cycles of menstruation and conceived spontaneously. During pregnancy, estradiol increased and FSH and LH decreased. The finding confirms restoration of negative feedback of estradiol on FSH and LH secretion. The pregnancy course was uneventful and enlargement of ovaries did not occur.

Adenoma↗