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Biomedical subjects

Y Takaoka

Publications and source records attributed to Y Takaoka.

At least 19 recordsLinked to original sources
PubMed1995

CT-assisted percutaneous anterior cordotomy: technical note.

Percutaneous radiofrequency cordotomy remains a useful modality for managing selected patients with unremitting pain due to malignancy. Although the lateral C1-C2 method is widely used, certain clinical situations may call for a low anterior cervical approach via the disc space. The anterior method can be technically exacting due to the need for precision in the angle of approach at the point of disc space entry. Here we describe how CT-imaging can be used to simplify target localization during percutaneous anterior cervical cordotomy.

Cordotomy↗
PubMed1995

The effect of a TXA2 receptor antagonist ON-579 on experimental allergic reactions.

The effect of a thromboxane A2 (TXA2) receptor antagonist, ON-579, on experimental allergic skin and airway reactions was studied in vivo. ON-579 at doses of 1 and 20 mg/kg clearly inhibited U-46619-induced increases in respiratory resistance (Rrs) in guinea pigs. ON-579 at doses of 1, 20 and 50 mg/kg inhibited the aerosolized antigen-induced biphasic increase in Rrs in guinea pigs. Moreover, ON-579 clearly inhibited repeated aeroantigen-induced airway hyperreactivity in guinea pigs. ON-579, however, did not have any significant effects on allergic cutaneous reactions in rats. These results suggest that ON-579 is a relatively selective TXA2 antagonist, especially in the airways, and indicate the efficacy of ON-579 on antigen-induced increase in airway resistance and antigen-induced airway hyperreactivity in guinea pigs.

Aerosols↗
PubMed1995

Plasma membrane block to polyspermy in human oocytes and preimplantation embryos.

The existence and time course of the human plasma membrane block to polyspermy were investigated by an in vitro fertilization assay using zona pellucida-free unfertilized oocytes, pronuclear oocytes and embryos. In the time course study using a high sperm concentration (10(5) spermatozoa ml-1), the number of penetrating spermatozoa at 30 and 60 min after insemination were 1.3 +/- 0.3 and 2.9 +/- 0.4, respectively. By 2 h after insemination, spermatozoa penetration reached a maximum. A lower maximum number of penetrating spermatozoa was observed at a low sperm concentration (10(4) spermatozoa ml-1), but the number of penetrating spermatozoa still reached a maximum by 2 h after insemination. A reinsemination experiment demonstrated that the number of penetrating spermatozoa was not significantly different between control and reinseminated oocytes, while sperm penetration was not observed in the oocyte beyond the two-cell stage. Furthermore, the number of binding spermatozoa decreased after fertilization and most of the four-cell stage embryos displayed no sperm binding. These results suggest that the plasma membrane block plays an important role in the prevention of polyspermy in the human oocyte, and that the plasma membrane block may involve permanent changes in the binding or fusion ability of spermatozoa in the oolemma after fertilization.

Blastocyst↗
PubMed1995

The use of zona-free aged unfertilized human oocytes as a predictor for successful subzonal insemination.

OBJECTIVE: To examine the reliability of the zona-free aged (1 day old) human unfertilized oocyte sperm penetration assay for assessing sperm fertilizing ability and to determine the predictive value of this assay for subsequent subzonal insemination (SUZI) outcomes. DESIGN: A total of 253 unfertilized oocytes from total fertilization failure patients and from good fertilization rate (> 70%) patients in standard IVF were inseminated with donors' spermatozoa, and penetration rates were compared in each group. Two hundred seventy-two unfertilized oocytes from total fertilization failure, poor fertilization (< 30%), and normal fertilization (> 30%) were inseminated with husbands' spermatozoa, and penetration rates were compared between the three groups. In 29 patients, the results of the zona-free assay performed in previous IVF were compared with the fertilization rates of subsequent SUZI. RESULTS: In the zona-free assay using donors' spermatozoa, there was no difference in penetration rates between the two groups (109/122, 89.3% versus 114/131, 87.0%). Penetration rates using partners' spermatozoa were positively correlated with fertilization rates in standard IVF (total fertilization failure 34/75, 45.3%; poor fertilization 56/77, 72.7%; normal fertilization 108/120, 90.0%). There was a significant difference in fertilization rates after SUZI between the patients with negative and positive penetration in zona-free assay (4/53, 7.5%, versus 54/174, 31.0%). CONCLUSION: The zona-free human oocyte assay may primarily reflect sperm fertilizing ability. This asssay also could be a reliable predictor for subsequent SUZI outcome.

Cellular Senescence↗
PubMed1994

Extracts of porcine pancreas prevent progression of hypercalcemia and cachexia and prolong survival in nude mice bearing a human squamous carcinoma.

Porcine pancreatic extracts (PXs) have previously been shown to decrease blood ionized calcium in BALB/c mice (T. Yoneda, Y. Takaoka, and G. R. Mundy. FEBS Lett., 278: 171-174, 1991). In the present study, we show that the PX is effective in preventing progression of hypercalcemia and decreasing osteoclastic bone resorption associated with a human squamous carcinoma in nude mice. PX inhibited osteoclast-like cell formation in mouse bone marrow cultures and bone resorption in organ cultures of fetal rat long bones which had been stimulated by serum-free culture supernatants of this cancer. In addition, PX increased food intake, decreased weight loss, and prevented development of cachexia. In parallel with these effects, PX prolonged survival of tumor-bearing animals. PX might have therapeutic potential for management of hypercalcemia and cachexia associated with malignancy.

Animals↗
PubMed1994

The model of arthritis induced by superantigen in mice.

Subcutaneous injection of Staphylococcal enterotoxin B (SEB) produced by Staphylococcus aureus, caused severe arthritis in DBA/1J mice which had been previously immunized with bovine type II collagen. The severity of this arthritis was dose dependent and prolonged joint inflammation with erosion of bone was observed. Anti- type II collage antibodies were detected in the serum of arthritic mice. Effector T cells against type II collagen were also detected by means of delayed type hypersensitivity in the skin. Moreover, a significant decrease in the ratio between T cells and B cells and an increase in the ratio between CD4+ cells and CD8+ cells was observed in spleen cells from arthritic mice. Prednisolone suppresses the induction and development of clinical signs of arthritis in mice. This evidence suggests that this experimental arthritis model may provide a means to examine the role of superantigens and the efficacy of pharmacological agents for the treatment of rheumatoid arthritis.

Animals↗
PubMed1994

A randomized prospective study of gonadotrophin with or without gonadotrophin-releasing hormone agonist for treatment of unexplained infertility.

The use of gonadotrophin-releasing hormone agonist (GnRHa) in combination with human menopausal gonadotrophin (HMG) for ovulation induction has been advocated for the treatment, particularly by in-vitro fertilization (IVF) of various types of infertility. The present study was designed to compare the clinical efficacy of HMG alone with a short protocol of GnRHa/HMG for treatment of unexplained infertility. A total of 91 couples with unexplained infertility were randomly assigned to one of two treatments; either HMG with intra-uterine insemination (IUI) (45 patients, 62 cycles) or GnRHa/HMG with IUI (46 patients, 69 cycles) treatments. Progesterone concentrations on the day of human chorionic gonadotrophin (HCG) administration were significantly higher in HMG (1.5 +/- 0.9 ng/ml) versus GnRHa/HMG (0.8 +/- 0.6 ng/ml; P < 0.05) cycles. Furthermore, GnRHa suppressed the occurrences of premature luteinization (GnRHa/HMG 5.8% and HMG 24.2% respectively). However, there were no significant differences in HMG dose requirements, plasma oestradiol concentrations or follicular development on the day of HCG administration between the two groups. Nor were any significant differences found in the pregnancy rates between the two treatment protocols (GnRHa/HMG 13.0% and HMG 11.3% respectively). Our results suggest no beneficial effect of GnRHa/HMG compared to HMG alone for the treatment of unexplained infertility, based on pregnancy rates.

Adult↗
PubMed1994

A novel mutation in the erythrocyte protein 4.2 gene of Japanese patients with hereditary spherocytosis (protein 4.2 Fukuoka).

Human erythrocyte protein 4.2 (band 4.2; pallidin) is a major membrane protein that comprises 5% of the total weight of the human erythrocyte membrane. Deficiencies of this protein have been observed in hereditary spherocytosis with anaemia, suggesting a role of protein 4.2 in erythrocyte stability and integrity. The molecular basis of this disorder remains unknown. As a first step in elucidating the pathogenesis of hereditary spherocytosis associated with protein 4.2 deficiency, we cloned and sequenced the erythrocyte protein 4.2 gene from a normal Japanese person. We prepared sets of oligonucleotide primers for polymerase chain reaction (PCR) and determined nucleotide sequences of exons and exon-intron boundaries of the protein 4.2 gene from three unrelated Japanese patients with hereditary spherocytosis due to a complete defect of protein 4.2, using PCR-related techniques. Two patients were homozygous for a missense mutation in codon 142 with the Ala (GCT)-->Thr (ACT) amino acid substitution that has been reported previously (protein 4.2NIPPON), whereas one patient was compound heterozygous for the same missense mutation in codon 142 and a guanine-adenine transition in codon 119 that changes the codon for Trp (TGG) to the termination codon (TGA) (protein 4.2Fukuoka). No additional mutation was identified in other exons of the protein 4.2 genes. Dot-blot hybridization with allele-specific oligonucleotide probes showed that homozygosity for the missense mutation in codon 142 and compound heterozygosity for the codon 142 and the codon 119 mutations were related to protein 4.2 deficiency in the families. Although two alleles of missense mutation of the codon 142 were also detected in 100 alleles of healthy Japanese, results obtained in this study indicate that the two mutations described above are closely related to the pathogenesis of hereditary spherocytosis due to protein 4.2 defect.

Adult↗
PubMed1994

Evaluation of intercostal pacing to provide artificial ventilation in quadriplegics.

The purpose of this study was to assess the utility of intercostal muscle pacing by spinal cord stimulation (SCS) to provide artificial ventilation in ventilator-dependent quadriplegic patients. Five ventilator-dependent quadriplegics with phrenic nerve injury (and therefore not candidates for phrenic nerve pacing) were studied. During an initial surgical procedure, a quadripolar epidural disc electrode was positioned on the ventral portion of the upper thoracic spinal cord via a hemilaminectomy and subsequently connected to a radio-frequency receiver implanted subcutaneously over the anterior rib cage. In four of the five patients, initial SCS stimulation resulted in inspired volumes between 150 and 240 ml. Stimulation resulted in no effect in one patient, due to probable cystic degeneration of the thoracic spinal cord. Reconditioning of the intercostal muscles caused substantial increases in inspired volume in three of four patients of 670 to 850 ml. In one patient, reconditioning resulted in a much smaller increase (to 470 ml). The maximum duration that ventilation could be sustained by low-frequency (13 Hz) intercostal pacing ranged between 20 min and 2 3/4 h. Our findings indicate that intercostal pacing via SCS does not result in sufficient inspired volume production to support ventilation for prolonged periods. However, this modality may be a useful adjunct to enhance tidal volume in patients with suboptimal inspired volume by phrenic nerve pacing.

Chronic Disease↗
PubMed1994

Intraventricular cerebral neuroblastoma. Analysis of subtypes and comparison with hemispheric neuroblastoma.

Two cases of intraventricular neuroblastomas were compared with cases of intraventricular and hemispheric neuroblastomas that have been reported in the published literature. The following order of tumor subtypes was found in patients with increasing age: hemispheric neuroblastoma, intraventricular undifferentiated neuroblastoma, intraventricular differentiated neuroblastoma, and intraventricular neurocytoma; for patients with intraventricular neuroblastomas, this was also the order of increasing cellular maturation and survival. Neuronal morphologic or epitope differentiation was associated with a longer survival time than lack of differentiation by Kaplan-Meier product-limit estimates and with a better survival rate (chi 2) for intraventricular tumors but not for hemispheric tumors. Pathologic distinction of a neurocytoma was confirmed with immunostaining or ultrastructural studies that suggested that a neurocytoma is a matured neuroblastoma of a granule-cell (interneuron) phenotype. Differences among neuroblastoma groups bolster previous suggestions that intraventricular tumors arise differently than do cases of hemispheric tumors and follow a more benign course when neuronal differentiation is present.

Adult↗
PubMed1993

Effects of platelet activating factor on human sperm function in vitro.

The direct effects of platelet activating factor (PAF) and the specific PAF receptor antagonist, CV-3988, on the fertilizing ability of human spermatozoa were investigated. PAF (10(-7)-10(-11) M) increased the human sperm penetration rates in a sperm penetration assay at all doses > 10(-11) M. In contrast, treatment of the spermatozoa with 10(-5) CV-3988 caused a significant decrease in human sperm penetration of zona-free hamster oocytes and adversely affected sperm motility after 24 h of incubation. This suppression was reversed by the addition of PAF. The acrosome reaction was also enhanced by PAF treatment of spermatozoa but this effect was not observed in calcium-free medium. While 10(-5) M CV-3988 decreased the acrosome reaction, the inhibition was also reversed by the addition of PAF. These results suggest that PAF may have a direct role in the fertilizing capacity of human spermatozoa. These findings also suggest that PAF may have a clinical application in an in-vitro fertilization programme.

Acrosome↗
PubMed1991

Porcine pancreas extract decreases blood-ionized calcium in mice and inhibits osteoclast formation and bone resorption in culture.

Patients with acute pancreatitis commonly manifest hypocalcemia for reasons which are unknown. We found that porcine pancreas extracts (PX) significantly decreased blood-ionized calcium in Balb/c mice. Partially-purified PX with a molecular mass of approximately 27 kDa decreased blood-ionized calcium in the mice. Partially-purified PX suppressed not only 45Ca release from fetal rat long bones which had been stimulated by parathyroid hormone, interleukin-1 alpha, tumor necrosis factor, transforming growth factor-alpha, 1,25-dihydroxyvitamin D3 and prostaglandin E2, but tartrate-resistant acid phosphatase-positive multinucleated cell formation in the presence of 1,25-dihydroxyvitamin D3 in mouse marrow cultures. The results suggest that there is an as yet-unidentified bone metabolism-regulating substance in porcine pancreas which might be responsible for the hypocalcemia associated with acute pancreatitis.

Animals↗
PubMed1991

A "PICA communicating artery" aneurysm: case report.

We present an unusual case of an aneurysm of the distal posterior inferior cerebellar artery (PICA). The aneurysm was associated with a unilateral PICA that supplied both cerebellar hemispheres and arose from an anastomotic vessel to the contralateral circulation, a branch of the contralateral PICA. Such an aneurysm has not been reported previously. The associated of vascular anomalies with aneurysms of the PICA is discussed.

Cerebellum↗
PubMed1990

[A study on measurement of auditory reaction time].

In order to determine auditory reaction time, different test methods for central conducting modes (simple reaction, choice reaction, simultaneous reaction and time lag reaction) were carried out on normal subjects. As test sounds, pure tone, white noise and Japanese vowels were employed. The following results were obtained. 1) The results were simple reaction time 186 ms, choice reaction time 283 ms, simultaneous reaction time 288 ms and time lag reaction time 370 ms (delay time 50 ms), 361 ms (delay time 100 ms), 298 ms (delay time 200 ms) and 273 ms (delay time 400 ms). 2) Simple reaction time by stimulus sound pressure level of over 40 dB sensation level was almost a certain value, the determination of reaction time of about 40 dB sensation level was considered to be suitable. 3) In each sound and each examination method, no significant differences between reaction times according to left and right ears were found. 4) According to examination method, the tendency of significant shortening was found only in white noise. This was considered to be due to broad frequency component of white noise or its tonality, accordingly if it was used as test sound, it needed to be loudness balanced with other test sound. 5) In simultaneous reaction and time lag reaction, such acoustic psychological problems as binaural fusion, interaural attentional switching mechanism and warning effect of preceding sound needed to be considered. 6) In the subjects having normal auditory function, it might be estimated that identification time may be about 100 ms and discrimination time may be about 70-80 ms. 7) Auditory reaction time includes the time required in central information conducting process as direct real time, and conveniency of its examination items were superior to the other methods. Also, the analyses of identification time and discrimination time were considered to be applicable for the diagnosis of quantitative auditory function of the central auditory handicapped persons in future.

Adult↗