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C Oka

Publications and source records attributed to C Oka.

At least 19 recordsLinked to original sources
PubMed2006

Artificial shrinkage of blastocoeles using either a micro-needle or a laser pulse prior to the cooling steps of vitrification improves survival rate and pregnancy outcome of vitrified human blastocysts.

BACKGROUND: Since we reported the first successful birth from a blastocyst vitrified using a cryoloop technique, our results showed that the survival rate of vitrified blastocysts was negatively correlated with the expansion of the blastocoele. We speculated that a large blastocoele may disturb the efficacy of vitrification. Therefore, we evaluated the effectiveness of artificial shrinkage (AS) of blastocoeles before vitrification, on increasing the survival rate of vitrified blastocysts. METHODS: Supernumerary expanded blastocysts on day 5 were vitrified after AS, which was performed by puncturing the blastocoele with a micro-needle, or by making a hole in the blastocoele with a laser pulse. After warming, viable blastocysts (confirmed by re-expansion of the blastocoele) were transferred to patients with hormone replacement cycle. We compared these data with those of our previous report where AS was not carried out. RESULTS: The survival rate was significantly higher (97.2%, 488/502) in this study than that of the previous report (86%). After 266 transferable cycles, 160 patients became pregnant (60.2%), which was significantly higher than our previous results (34.1%, 29/85). The implantation rate was 46.7% (209/448). CONCLUSIONS: Our results revealed that the survival rate and the pregnancy rate of vitrified expanded and hatching blastocysts can be improved by using AS to collapse the blastocele before vitrification.

Adult↗
PubMed2003

Vitrification of human blastocysts using cryoloops: clinical outcome of 223 cycles.

BACKGROUND: The need to cryopreserve human blastocysts is increasing. The successful birth has been reported of a baby from a blastocyst vitrified using the cryoloop technique. The present study expands on this earlier report to confirm the effectiveness of this vitrification procedure. METHODS: In patients undergoing IVF at one of three clinics, supernumerary blastocysts on day 5 or 6 at various stages of development were vitrified using cryoloops. RESULTS: Of 725 vitrified blastocysts, 583 (80.4%) survived. After the transfer of 493 blastocysts in 207 cycles, 76 women (37%) became clinically pregnant. Among these women, 21 pregnancies ended in miscarriage, 23 healthy babies were born in 18 deliveries, and 37 pregnancies are ongoing. The survival rate of day 5 blastocysts (87%) was higher than that of day 6 blastocysts (55%), but implantation rates and pregnancy rates were not statistically significantly different. CONCLUSIONS: Clinical outcomes with 725 blastocysts and 207 transfers showed that vitrification using cryoloops is effective and practical for the cryopreservation of human blastocysts. Early blastocysts on day 5 seem to be the most suitable in terms of stage and age for cryopreservation, but developed and day 6 blastocysts can also be cryopreserved.

Adult↗
PubMed2001

p48 subunit of mouse PTF1 binds to RBP-Jkappa/CBF-1, the intracellular mediator of Notch signalling, and is expressed in the neural tube of early stage embryos.

BACKGROUND: Development of the pancreas and the nervous tissues is regulated by common transcription factors. A basic helix-loop-helix protein, p48 of pancreas transcription factor 1 (PTF1), is essential for differentiation of the exocrine acinar cells. RESULTS: We isolated PTF1 p48 from 9.5-day mouse embryos as a binding protein of RBP-Jkappa, a mediator of Notch signalling. p48 bound to RBP-Jkappa more strongly than and in a distinct way from Notch1. In 9.5-12.5 day embryos, p48 was expressed in the dorsal part of the neural tube as well as in the pancreatic buds. Two lines of evidence suggested functions of p48 in neurogenesis: (i) expression of p48 was induced in P19 cells when they committed to neural fate upon retinoic acid treatment, and (ii) p48 over-expressed in Xenopus embryos repressed the development of neuronal precursors. p48 inhibited the MASH1-activated transcription from the E-box, while p48 stimulated transcription from the PTF1 motif synergistically with E47. The p48/E47-activated transcription from the PTF1 motif was stimulated further by RBP-Jkappa and RBP-Jkappa derivatives that mimicked the active RBP-Jkappa/Notch complex. CONCLUSIONS: In developing embryos, p48 is expressed in both the nervous system and the pancreas. p48 inhibits neuronal differentiation. We propose possible mechanisms for this inhibition.

3T3 Cells↗
PubMed2000

Rapid serum vancomycin assay by high-performance liquid chromatography using a semipermeable surface packing material column.

A new isocratic high-performance liquid chromatographic (HPLC) assay has been developed for vancomycin that uses direct injection of microquantities of serum into a separation column filled with octyl-C(8) silica support that has a semipermeable surface. A mixture of disodium hydrogen phosphate buffer (pH 7.0) and acetonitrile is used as the mobile phase, and vancomycin is directly detected at 240 nm. The minimum limit of detection was 0.5 microg/ml at a signal-to-noise ratio of 3:1. Linearity was established from 0 to 100 microg/ml. The coefficient of variation for within-run reproducibility was 1.1-2.7% for a concentration range of 2.9-52.5 microg/ml; for day-to-day reproducibility it was 4.0% and 3.1% for a concentration range of 5.8-26.4 microg/ml, and the recovery rate was 94-105%. There was no interference from 41 antibiotics or other drugs currently in use. The correlation coefficient between the fluorescence polarization immunoassay (x) and this method (y) was 0.995 with a linear equation, y = 1.06x - 0.924. This method is simple, rapid, and provides an economical quantification of serum vancomycin.

Anti-Bacterial Agents↗
PubMed1999

Human lysozyme secretion increased by alpha-factor pro-sequence in Pichia pastoris.

To get high level secretion of human lysozyme in Pichia pastoris, the following three signal sequences and one prepro sequence were evaluated: chicken lysozyme signal peptide, leucine-rich artificial signal peptide, Saccharomyces invertase signal peptide, and Saccharomyces prepro sequence of alpha factor (MF-alpha Prepro). Transformants harboring a lysozyme gene with MF-alpha Prepro secreted 20-fold more lysozyme than those harboring the lysozyme gene with any one of the other three signal sequences. Three mutant leader sequences derived from MF-alpha Prepro were constructed to discover the function of the pro region. The secretion was dramatically decreased by eliminating the pro region of MF-alpha Prepro. In contrast, MF-alpha Prepro with the EAEAEA sequence directed the secretion of an equivalent level of lysozyme having the extra amino acids (EAEAEA) in its N-terminus. For the effective secretion of native human lysozyme, MF-alpha Prepro without any spacer sequences was most suitable. The secreted protein by MF-alpha Prepro construct was identical with the authentic human lysozyme, judging from N-terminal amino acid sequencing and molecular mass spectrometric and crystallographic analysis.

Amino Acid Sequence↗
PubMed1995

Epidemiologic characteristics of rhegmatogenous retinal detachment in Kumamoto, Japan.

BACKGROUND: The epidemiology of rhegmatogenous retinal detachment in Asians is not well known. We studied the epidemiologic characteristics of rhegmatogenous retinal detachment in Kumamoto, Japan. METHODS: The study was based on a retrospective chart review of hospital patients who were treated for primary rhegmatogenous retinal detachment in 1990. The data were collected from seven hospitals in the Kumamoto area. RESULTS: From a population of 1 840 000, 192 residents developed retinal detachment. The annual incidence was therefore 10.4 per 100 000 population (9.6 for males, 11.2 for females). The incidences of three types of detachment-nontraumatic phakic, aphakic, and blunt trauma--were 9.8, 0.5 and 0.2 per 100 000 population, respectively. In 109 of 180 patients (60.6%) with nontraumatic phakic detachment, retinal breaks were associated with lattice degeneration. In females, 14 of 106 nontraumatic phakic cases (13.2%) were secondary to macular holes. CONCLUSION: Compared with previously published studies from other countries, the incidence of detachments associated with lattice degeneration and macular hole was higher, while the incidences of aphakic detachment and detachment due to blunt trauma were lower in Japan. Racial factors and living habits may affect the development of retinal detachment.

Adolescent↗
PubMed1995

V(D)J recombination of immunoglobulin genes.

We have constructed transgenic mice carrying an artificial substrate of V(D)J recombination. In this substrate, the only DNA fragments derived from Ig genes were short stretches of recombination signal sequences. This artificial substrate was rearranged at high frequency in lymphocytes, although in non-lymphoid cells no rearrangement was detected even by a sensitive PCR assay. This result indicates that the V(D)J recombination requires only the signal sequences and that a recombination similar to the V(D)J recombination does not occur in non-lymphoid tissues including the central nervous tissue. A protein binding to the V(D)J recombination signals was purified and its cDNA was cloned. This protein, termed RBP-J kappa, was initially considered to be involved in V(D)J recombination because of its DNA binding specificity and structural similarity to site-specific recombinases known as the integrase family. However, further study on the Drosophila homolog of RBP-J kappa indicated that RBP-J kappa probably functions as a transcription factor in the differentiation of the peripheral nervous tissues. The exact function of RBP-J kappa is still unknown. Analogous to the Drosophila gene, it is suggested that mouse RBP-J kappa participates in the regulation of differentiation of various tissues.

Amino Acid Sequence↗
PubMed1995

Loss of immunostaining of the RBP-J kappa transcription factor upon F9 cell differentiation induced by retinoic acid.

RBP-Jkappa is a novel type of transcriptional regulatory protein that does not contain any known DNA-binding motif. We raised anti-RBP-Jkappa monoclonal antibodies (K0043 and T6709) to investigate the roles of RBP-Jkappa in cell differentiation. These antibodies stained nuclei of undifferentiated embryonic stem cells and F9 cells but not those of the other differentiated cell lines tested so far although the RBP-Jkappa protein is expressed at similar levels. Interestingly, differentiated F9 cells lost the immunostaining reaction with the anti-RBP-Jkappa monoclonal antibodies. Biochemical subcellular fractionation study showed that the majority of RBP-Jkappa was localized in nuclei of F9 cells and that there are at least two forms of the RBP-Jkapppa protein in the nuclei of undifferentiated F9 cells, a free form and a chromatin-bound form. Upon induction of F9 cell differentiation, free nuclear RBP-Jkappa disappeared concomitantly with the loss of immunostaining, suggesting that the anti-RBP-Jkapppa antibodies cannot recognize chromatin-bound RBP-Jkappa. Since there is no evidence to indicate covalent modification of RBP-Jkappa, we assume that chromatin-bound RBP-Jkappa interacts with a large number of proteins which block the exposure of RBP-Jkappa epitopes to the monoclonal antibodies.

3T3 Cells↗
PubMed1995

Disruption of the mouse RBP-J kappa gene results in early embryonic death.

The RBP-J kappa protein is a transcription factor that recognizes the sequence C(T)GTGGGGA. The RBP-J kappa gene is highly conserved in a wide variety of species and the Drosophila homologue has been shown to be identical to Suppressor of Hairless [Su(H)] which plays important roles in the development of the peripheral nervous system. To explore the function of the RBP-J kappa gene in mouse embryogenesis, a mutation was introduced into the functional RBP-J kappa gene in embryonic stem (ES) cells by homologous recombination. Null mutant ES cells survived but null mutant mice showed embryonic lethality before 10.5 days of gestation. The mutant mice showed severe growth retardation as early as 8.5 days of gestation. Developmental abnormalities, including incomplete turning of the body axis, microencephaly, abnormal placental development, anterior neuropore opening and defective somitogenesis, were observed in the mutant mice at 9.5 days of gestation. RBP-J kappa mutant embryos expressed a posterior mesodermal marker FGFR1. Their irregularly shaped somites expressed a somite marker gene Mox 1 but failed to express myogenin. The RBP-J kappa gene was revealed to be essential for postimplantation development of mice.

Animals↗
PubMed1994

A yeast gene necessary for bud-site selection encodes a protein similar to insulin-degrading enzymes.

Cells of the yeast Saccharomyces cerevisiae choose bud sites in a non-random spatial pattern that depends on mating type: axial for haploid cells and bipolar for a/alpha diploid cells. We identified a mutant yeast, axl 1, in which the budding pattern is altered from axial to bipolar. Expression of the AXL1 gene is repressed in a/alpha diploid cells. With the ectopic expression of AXL1, a/alpha cells exhibited an axial budding pattern, thus AXL1 is a key morphological determinant that distinguishes the budding pattern of haploid cells from that of a/alpha diploid cells. AXL1 encodes a protein similar in sequence of the human and Drosophila insulin-degrading enzymes and to the Escherichia coli ptr gene product. The axial budding pattern might result from degradation of a target protein by the putative Axl1 protease.

Amino Acid Sequence↗
PubMed1994

The age of onset of posterior vitreous detachment.

The age of onset of posterior vitreous detachment (PVD) was studied in 930 eyes with a clearly defined onset time and no vitreoretinal diseases except refractive error or equatorial degeneration. We found a positive correlation between onset age of PVD and refractive error, with the regression line y = 0.91 x + 60.93 (y onset age, x diopter of refractive error). The higher the degree of myopia, the younger the onset age of PVD. Comparing onset ages for 240 eyes from males and 690 eyes from females, there was a possible tendency toward a lower PVD onset age for females. There was no significant difference in onset age between 112 eyes with and 818 eyes without equatorial degeneration of the retina.

Adult↗
PubMed1994

Retinal detachment with atopic dermatitis similar to traumatic retinal detachment.

PURPOSE: The cause of retinal detachment (RD) with atopic dermatitis remains uncertain. The purpose of this study is to show that the probable cause of RD with atopic dermatitis is ocular contusion. METHODS: The authors retrospectively compared the fundus findings of 24 eyes (16 patients) that had RD and atopic dermatitis with 36 eyes (36 patients) that had traumatic RD. RESULTS: The authors found similar characteristics. Retinal breaks at vitreous base borders characterized by ocular contusion occurred in 79.2% of eyes with RD and atopic dermatitis and in 75.0% of eyes with traumatic RD. Irregular retinal traumatic breaks in the equatorial zone occurred in 20.8% of eyes with RD and atopic dermatitis and in 47.2% of eyes with traumatic RD. Objective signs of ocular contusion outside the retina appeared in 54.2% of eyes with RD and atopic dermatitis. CONCLUSIONS: The authors' data support the conclusion that self-inflected ocular contusion by tapping the eyes can cause RD with atopic dermatitis.

Adolescent↗
PubMed1992

Survey of 1120 Japanese women with a history of recurrent spontaneous abortions.

Our recent 7-year clinical survey showed that among the 1120 women with repeated spontaneous abortions registered in this clinic, 2898 out of a total of 3216 pregnancies (90.1%) had terminated in spontaneous abortion. Among these wastages, 84.2% occurred before 12 weeks of gestation, and 11.1 percent occurred between 12 and 15 weeks. Through routine examination of reproductive wastage, 82 (9.9%) of the 825 Japanese couples examined were shown to have either a chromosomal abnormality or normal variants in the wife and/or husband, thus demonstrating no racial difference in the incidence of chromosomal abnormalities in infertile patients in comparison with studies performed in other countries. One hundred and forty-seven congenital uterine anomalies (14.7%) were found in 1000 hysterosalpingographies, and 12 of 148 examined females were positive for anti-cardiolipin antibody. 393 other females with no major abnormalities likely to induce spontaneous abortions were indicated for immunotherapy. Ample time spent on genetic counseling prevented further reproductive wastage, and ideal metroplasty resulted in a successful post-operative pregnancy course in more than 85% of cases. Immunosuppressant and anticoagulant therapy decreased the serum titer of anti-cardiolipin antibody, enabling pregnancies to be maintained to term. Immunotherapy utilizing the husband's lymphocytes also brought more than 80% of pregnancies to successful completion, with 200 deliveries achieved with this therapy. In contrast, 64.1% of pregnancies again terminated spontaneously in patients who were indicated for immunotherapy but did not receive treatment. The findings of the present study suggest that the causes of reproductive wastage, especially the etiology of early recurrent spontaneous abortion, are complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Habitual↗
PubMed1992

Genomic organization of mouse J kappa recombination signal binding protein (RBP-J kappa) gene.

We have isolated a cDNA clone (RBP-2) for the protein (RBP-J kappa) which binds to immunoglobulin recombination signals with 23-base pair spacers (Matsunami, N., Hamaguchi, Y., Yamamoto, Y., Kuze, K., Kangawa, K., Matsuo, H., Kawaichi, M., and Honjo, T. (1989) Nature 342, 934-937). During further screening of a cDNA library from the same mouse pre-B cell line (38B9), we have isolated a second cDNA clone (RBP-2N) which differs from RBP-2 in its 5' sequence. RNase protection assays indicated that the RBP-2N type mRNA was produced in 10-20 times the quantity as RBP-2 mRNA. To elucidate the relationship between these two mRNAs, we analyzed the genomic organization of the RBP-J kappa gene. Southern hybridization of mouse genomic DNA detected at least 7 EcoRI fragments hybridizing to an RBP-2 cDNA probe, suggesting a complex structure for the RBP-J kappa gene. Cloning of each EcoRI fragment revealed one functional RBP-J kappa gene and three related genes. The functional gene was composed of 11 exons and spanned at least 50 kilobase pairs. The sequence of exon 1 and its 5'-flanking region contained a GC-rich promoter-like region but no apparent TATA box. The initiation site of transcription was heterogeneous, and the two types of mRNA are produced from the same exon by transcription initiation at different sites and by different usage of splice signals. Two of the three related genes were processed pseudogenes with scattered stop codons. The other was also a processed gene with a sequence exactly the same as that of RBP-2, except that this gene lacked the sequence corresponding to the first exon of the functional gene.

Animals↗
PubMed1991

Neovascularization of the iris in rhegmatogenous retinal detachment.

To identify conditions associated with neovascularization of the iris in rhegmatogenous retinal detachment, we examined 36 eyes with this disorder seen at our hospital between 1979 and 1990. Clinical courses of disease were divided into the following three groups: (1) neovascularization of the iris without a history of a vitreoretinal operation (four eyes), (2) neovascularization of the iris after an unsuccessful vitreoretinal operation (26 eyes), and (3) neovascularization of the iris after surgical complications (six eyes). In all eyes of Groups 1 and 2, retinal detachment persisted at the onset of iris neovascularization; however, in six eyes, iris neovascularization subsided after retinal reattachment. Characteristic features of Groups 2 and 3 were patient age of 50 years or more, severe myopia, a history of increased intraocular pressure, a history of choroidal detachment, and a large scleral buckle.

Age Factors↗
PubMed1991

Recombination of exogenous interleukin 2 receptor gene flanked by immunoglobulin recombination signal sequences in a pre-B cell line and transgenic mice.

We have constructed a plasmid, pLTR100, which contains human interleukin 2 receptor light (IL-2R L) chain cDNA in the inverted orientation relative to the upstream SV40 promoter. The cDNA segment is flanked by the immunoglobulin gene recombination signal sequences so that the cDNA segment can invert and the human IL-2R L chain is subsequently expressed under the control of the SV40 promoter. A murine pre-B cell line, 38B9, transfected with pLTR100 began to express the human IL-2R L chain on the cell surface. The frequency of human IL-2R L chain positive cells increased almost linearly up to 50% for 60 days of culture after transfection. Southern blot analysis and sequencing of the DNA fragments at the recombination junction confirmed that the cDNA segment was inverted in a signal sequence-dependent manner by the variable-diversity-joining recombination process. Transgenic mice bearing the recombination substrate DNA similar to pLTR100 expressed the human IL-2 L chain in the spleen, thymus, and bone marrow, but not in the other tissues examined at the detectable level. Both IgM- and CD3-positive cells expressed the human IL-2R L chain, indicating that this artificial DNA can serve as a substrate for recombination both in B- and T-cells and that another DNA segment may be necessary to confer the cell-type specificity on the substrate DNA.

Animals↗