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K Sekikawa

Publications and source records attributed to K Sekikawa.

At least 55 records · Page 3Linked to original sources
PubMed1998

Differential expression of activin subunits, activin receptors and follistatin genes in bovine oocytes and preimplantation embryos.

The presence of inhibin subunits (alpha, betaA and betaB), activin binding protein follistatin and activin receptors (ActR-I, ActR-IB, ActR-II and ActR-IIB) mRNA transcripts in bovine oocytes and preimplantation embryos was examined by reverse transcription-polymerase chain reaction. Immature and matured oocytes, zygotes, 2-cell, 3-4-cell, 5-8-cell, 9-16-cell embryos, morulae, blastocysts and hatched blastocysts were produced by in vitro maturation, fertilization and culture for this study. Activin betaA subunit and follistatin transcripts were detected in all of the stages tested. However, alpha subunit transcripts were detected only in oocytes (immature and matured), blastocysts and hatched blastocysts, and no betaB subunit transcripts were found in any of the stages. Whereas ActR-I transcripts were detectable in all stages, ActR-IB transcripts were not detectable in oocytes or embryos except in matured oocytes. Activin type II receptors (ActR-II and ActR-IIB) transcripts were detectable in oocytes and embryos except for ActR-IIB, which was not found in the 5-8-cell stage embryos. The results suggest that bovine embryos may produce activin A (homodimer of the betaA subunits) at least from zygotes to morulae. Furthermore, bovine oocytes and embryos express the activin receptors mainly by the combination of ActR-I and either ActR-II or ActR-IIB.

Activin Receptors↗
PubMed1998

Molecular cloning of bovine thyrotropin-releasing hormone receptor gene.

The genomic DNA encoding bovine Thyrotropin-Releasing Hormone Receptor (TRHR) was isolated from a bovine (Holstein) genomic library. Using PCR fragments of bovine candidate TRHR Transmembrane domain (TMD-III-IV) and C-terminus domain of mouse TRHR cDNA as probes, 9 x 10(5) plaques were screened to obtain several clones each containing the N-terminus or C-terminus domain. The bovine TRHR gene encoded 398 amino acids and has a long intron. The identity of the deduced amino acid sequence of bovine TRHR exceeded 88% that of mouse, rat or human. RT-PCR analysis indicated TRHR mRNA to be expressed in the pituitary and brain.

Amino Acid Sequence↗
PubMed1998

Genetic analysis of non-insulin-dependent diabetes mellitus in KK and KK-Ay mice.

The KK mouse is considered suitable as a polygenic model for human non-insulin-dependent diabetes mellitus. To identify the quantitative trait loci (QTLs) responsible for hyperglycemia and impaired glucose tolerance in KK mice, linkage analysis using 97 microsatellite markers was carried out in a 192 F2 progeny, comprising 93 mice with the a/a genotype at the agouti locus (chromosome 2) and 99 mice with the Ay/a genotype, produced by a cross between a C57BL/6J female and a KK-Ay (Ay congenic) male. In F2 a/a progenies, we identified a QTL for fasting glucose levels on chromosome 6 (LOD score 6.0) and three loci with suggestive linkage on chromosomes 3, 5 and 14, but could not identify loci accounting for glucose tolerance and plasma insulin levels. In F2 Ay/a progenies, there were no loci with statistically significant linkage, but three suggestive loci were identified: a locus for fasting glucose on chromosome 9, and two loci for glucose tolerance on chromosomes 1 and 8. It would thus appear that. although the fasting glucose level is controlled by QTLs in KK mice, these QTLs may be masked by the strong hyperglycemic influence of the Ay allele. Suggestive loci accounting for glucose tolerance may interact with the Ay allele, since these loci were identified only in F2 Ay/a progeny. This is consistent with the finding that the impaired glucose tolerance in KK mice is moderate and becomes overt when associated with the Ay allele.

Alleles↗
PubMed1998

Inhibition in a microgravity environment of the recovery of Escherichia coli cells damaged by heavy ion beams during the NASDA ISS phase I program of NASA Shuttle/Mir mission no. 6.

We participated in a space experiment, part of the National Space Development Agency of Japan (NASDA) Phase I Space Radiation Environment Measurement Program, conducted during the National Aeronautics and Space Administration (NASA) Shuttle/Mir Mission No. 6 (S/MM-6) project. The aim of our study was to investigate the effects of microgravity on the DNA repair processes of living organisms in the in orbit. Heavy ion beam radiation- or ç-irradiation-damaged biological samples of Escherichia coli and the radioresistant bacterium Deinococcus radiodurans were prepared and placed in a biospecimen box, which was loaded into the RRMD III sensor unit of the Space Shuttle. Two identical sets of samples were left in the Spacehab's Payload Processing Facility (SPPF) in Florida, USA, as a control. (flight No. STS-84) was launched from NASA John F. Kennedy Space Center (KSC) in Florida, USA, on May 15, 1997. The mission duration was 9.22 days. An astronaut activated the biological samples in the biospecimen box in the Spacehab during orbit in order to start repair of the DNA damaged by heavy ion beams or ç-irradiation and the samples were incubated for 19 h 35 min at about 22ûC, the cabin temperature. The control specimens in the SPPF were subjected to the same treatment under terrestrial gravity. After returned to earth, we investigated cell recovery by comparing the repair of the radiation-damaged DNA of E. coli and D. radiodurans in the microgravity environment in space with that on Earth. The results indicated that the DNA repair process of E. coli, but not of D. radiodurans, cells was inhibited in a microgravity environment.

Cell Survival↗
PubMed1998

[Effect of CDDP/5'-DFUR combination chemotherapy for advanced or recurrent gastric cancer].

CDDP/5'-DFUR combination chemotherapy was performed on 17 patients with non-resected and recurrent gastric cancer (clinical stage were IVb in all patients). They were treated with 1,400 mg/m2 of 5'-DFUR on days 1-4 orally following by withdrawal 10 days, every 2 weeks repeatedly and 80 mg/m2 of CDDP (c. i. v., on day 5, every 4 weeks). This chemotherapy was performed for at least 2 courses on all patients. Eight of 17 patients achieved a partial response and the overall response rate was 47.1% (differentiated type 57.1%, undifferentiated type 45.5%). Response rates of each lesion were as follows: primary foci 42.9%, abdominal lymph nodes 57.1%, hepatic metastasis 60.0% and ascites 33.3%, respectively. Improvement of performance status was seen in 12 of 17 patients (70.6%). The overall median survival time was 227 days. The median outpatient period was 113 days. There was no high-grade toxicity over grade 2. Therapeutic toxicity of grade 2 was manifested as renal dysfunction (23.5%), nausea/vomiting (17.6%), leukopenia (5.9%) and anemia (5.9%). We evaluated the therapeutic effect by visual examination after completion of the second course. However, poor effect and high incidence of renal dysfunction were found in patients treated with this therapy over four times. Therefore, the maximum effect seemed to be revealed after completion of the fourth course. From the present study, CDDP/5'-DFUR combination chemotherapy seems to be effective for patients with high-grade advanced gastric cancer and improved their quality of life.

Adenocarcinoma↗
PubMed1997

Differential patterns of blastulation in bovine morulae cultured in synthetic oviduct fluid medium containing FCS or BSA.

This study examined the effects of fetal calf serum (FCS) supplementation of culture medium on blastulation and hatching of bovine morulae cultured in vitro. The presumptive zygotes derived from in vitro maturation and fertilization (IVM/IVF) were cultured in the modified synthetic oviduct fluid medium containing 3 mg/ml BSA (mSOF-BSA). At 120 h post insemination, morulae were randomly assigned to culture with mSOF-BSA (control) or mSOF containing 5% FCS (mSOF-FCS) instead of BSA. The replacement of BSA with FCS in mSOF significantly increased the percentage of blastocyst formation from Day 6 to Day 10 (Day 0 = the day of in vitro insemination) and the hatching rate of embryos on Days 8 and 9. The total number of cells in morulae and blastocysts on Day 6, in blastocysts on Day 7, and in blastocysts and hatched blastocysts on Day 8 were similar among the treatments. However, the replacement of BSA with FCS in mSOF significantly increased the total number of cells in hatched blastocysts on Day 10. Although the time of blastulation of embryos was significantly accelerated by the replacement of BSA with FCS in mSOF, the total number of cells in embryos at blastulation was lowered. The total number of cells in embryos at blastulation showed a time-dependent decrease when the embryos were cultured in mSOF-BSA. In contrast, the total number of cells in embryos that were cultured in mSOF-FCS depended little on the time after in vitro insemination. The results indicate that FCS supplementation of culture medium increased the percentage of embryos developing to the blastocyst stage without an increase in the total number of cells. However, an acceleration in the hatching rate and an increase in the total number of cells in hatched blastocysts were observed, compared with that in BSA-supplemented medium. It is suggested that FCS in the culture medium initiates earlier blastulation with fewer total numbers of cells in the morulae than BSA during in vitro culture of bovine embryos.

Journal Article↗
PubMed1997

Suppression of concanavalin A-induced hepatitis in IFN-gamma(-/-) mice, but not in TNF-alpha(-/-) mice: role for IFN-gamma in activating apoptosis of hepatocytes.

Con A-induced hepatitis (Con A-hepatitis) is a hepatitis model in which hepatic injury is supposed to be caused by cytokines from activated T cells. To elucidate the pathogenesis of this disease, we analyzed the roles of IFN-gamma and TNF-alpha using deficient mice of these cytokines. Development of hepatitis was reduced significantly in IFN-gamma(-/-) mice, while susceptibility of TNF-alpha(-/-) mice was not changed. Interestingly, apoptotic cell death was observed in the affected livers of control or TNF-alpha(-/-) mice, but not in those of IFN-gamma(-/-) mice. Fas mRNA expression was increased in the livers of hepatitis mice, but less abundantly in those of IFN-gamma(-/-) mice. Since apoptosis of liver cells was rarely observed in Con A-treated lpr/lpr mice, involvement of the Fas-Fas ligand system in this apoptotic process was suggested. These observations suggest that IFN-gamma plays a central role in Con A-hepatitis by activating Fas-induced apoptosis of liver cells.

Animals↗
PubMed1997

Molecular cloning of bovine CD14 gene.

Genomic DNA encoding bovine CD14 was isolated from a bovine (Holstein) genomic library. Utilizing PCR fragment of mouse CD14 gene as a probe, we screened 9 x 10(5) plaques and obtained 3 clones containing the bovine CD14 gene. DNA sequencing showed that bovine CD14 gene encodes 373 amino acids, and the coding sequence was separated by a 90 nt intron. The identity of the deduced amino acid sequence of bovine CD14 was 61-73% to those of mouse, rabbit and human. Northern blot analysis revealed that CD14 mRNA (1.5 kb) was expressed in the lung. Expression of CD14 mRNA was stimulated about 2-fold in bovine peripheral blood macrophage activated with LPS in vitro.

Amino Acid Sequence↗
PubMed1997

Failure of germinal center formation and impairment of response to endotoxin in tumor necrosis factor alpha-deficient mice.

To study the pathophysiologic roles of TNF alpha, we produced TNF alpha gene-disrupted mice by gene targeting. TNF alpha-deficient mice develop normally without any alteration in the lymphocyte populations. However, in these mice, the germinal center formation in the peripheral lymphoid organs failed in response to the T cell-dependent antigens. TNF alpha-deficient mice are resistant to lethal doses of endotoxin and D-galactosamine without hepatocyte apoptosis, yet demonstrate thymus apoptosis. Our results indicated an important role for TNF alpha in germinal center formation and in the sepsis-induced hepatocyte apoptosis that precedes liver failure.

Animals↗
PubMed1994

Cloning of thyroid hormone receptor genes expressed in metamorphosing flounder.

Two distinct cDNAs encoding thyroid hormone receptors (THRs) were cloned from a lambda gt10 library prepared from the whole bodies of metamorphosing flounder larvae (Paralichthys olivaceus). Deduced amino acid sequences of the two isolated cDNAs shared 96% and 92% homologies in their DNA- and hormone-binding domains, respectively. These were highly conserved when compared to THRs for other vertebrates: 88-96% in the DNA-binding domain and 84-94% in the hormone-binding domain. Other receptors in the nuclear receptor family showed lower homologies than those of THRs. Both THRs for the flounder had higher homologies with the alpha-type THRs of other vertebrates than with the beta-type. Thus, the two THRs for flounder were designated as fTHR alpha A and fTHR alpha B.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence and transcriptional mapping of the major capsid protein gene of pseudorabies virus.

The gene encoding the 142-kDa major capsid protein (MCP142) of pseudorabies virus (PrV) was isolated and sequenced. Nucleotide sequence analysis revealed that the MCP142 gene has a single open reading frame of 3993 nucleotides (nt) encoding 1330 amino acids. The 4400-nt major RNA from the MCP142 gene was detected in PrV-infected cells. The 5' end of the transcript was located 60 nt upstream of the initiation codon. The 3' end of the transcript was located 18 nt downstream of a putative poly(A) signal sequence TATAAA and 133 nt downstream of the termination codon. In comparing amino acid sequence homology between MCP142 of PrV and other available herpesviruses MCP was shown to have 58% homology with herpes simplex virus type 1 and varicella-zoster virus, 27% with Epstein-Barr virus, and 24% with human herpesvirus 6 and human cytomegalovirus. It has greater homology with those of the alpha-herpesviruses than with those of the beta-herpesviruses and the gamma-herpesviruses.

Amino Acid Sequence↗
PubMed1991

Construction and functional characterization of mutants of the bovine leukaemia virus trans-activator protein p34tax.

The p34tax protein [p38tax, p34, p38(XBL), XBL-I] of bovine leukaemia virus (BLV) activates transcription from the BLV long terminal repeat (LTR) promoter. To analyse the functional properties of this protein, inframe insertions and internal deletions were systematically introduced in a plasmid-encoded copy of the p34tax gene. The abilities of wild-type and mutant genes to activate gene expression from the LTR promoter linked to the chloramphenicol acetyltransferase gene and to inhibit trans-activation by the wild-type protein were studied. The trans-activating activity of 14 of the 18 mutants tested was completely abolished, but four mutants each containing a lesion in the internal portion of the polypeptide retained activity. Taken together, these results suggest the presence of an internal region of the polypeptide where structural integrity is less strictly required for the functional activity of this protein. Among the mutants incompetent in the transactivation assay, only two with mutations in the N-terminal region of the polypeptide inhibited transactivation by the wild-type protein in a dose-dependent manner. These results facilitate understanding of the physiological function of the tax protein family.

Amino Acid Sequence↗
PubMed1990

Colonic mucosal changes in nude mice associated with orthotopic xenografts of human colon cancer cells.

We used the nude mouse tumour xenograft model to study the pathogenesis of mucosa alterations in the large bowel surrounding a carcinoma. In mouse colonic mucosa overlying HT-29 colonic carcinoma xenografts in the caecum, the crypts were elongated in comparison with those in distant mucosa and also frequently showed a shift towards sialomucin production. These features, which are comparable with socalled transitional mucosa (TM) in man, were absent in control animals inoculated with Indian Ink instead of HT-29 cells. Although the localization of the proliferative cell compartment in mouse colonic mucosa overlying HT-29 xenografts appeared to be confined to the lower half of the crypt as in normal mucosa, the relative length of the DNA synthesizing cell compartment along the crypts was slightly elongated. These data strongly suggest that TM should be regarded as a secondary phenomenon rather than a premalignant change in large intestinal epithelium and that higher proliferative activity of epithelial cells contributes little to the elongation of crypts in TM.

Animals↗
PubMed1990

Flow cytometric DNA analysis of thyroid carcinoma.

Abnormal DNA content has been considered as an additional criterion for determining the biological behavior of a tumor. Flowcytometric DNA analysis was done on 121 patients with thyroid carcinoma encountered during the period between 1975 and 1987. Tumor tissues were sampled from paraffin-embedded blocks and the histology of thyroid carcinoma found to consist of 91 papillary, 23 follicular, 2 medullary, 1 squamous cell and 4 anaplastic carcinomas. The incidence of aneuploidy in thyroid carcinoma was 7.4 per cent (9 patients) while that of diploidy was 92.6 per cent (112 patients). The aneuploid specimens consisted of 6 papillary, 1 follicular, 1 medullary and 1 anaplastic carcinomas and, of 4 anaplastic carcinoma patients with subsequent death within 6 months, only 1 was aneuploid. As an indicator of proliferative potential, S-phase fraction (SPF) was also determined by flow cytometry, but this could not be used as an independent prognostic factor. The aneuploid patients showed a significantly decreased survival rate (p less than 0.01). Thus, although DNA measurement proved useful for predicting the survival of aneuploid patients, there is some discrepancy between DNA content and the biological behavior of the tumor.

Adenoma↗
PubMed1989

Characteristics of lymphocytes appearing in persistent lymphocytosis induced experimentally in cattle by bovine leukemia virus infection.

Properties of peripheral blood lymphocytes (PBL) appearing during persistent lymphocytosis (PL) of cattle that was induced by inoculation of a large number of bovine leukemia virus (BLV)-infected lymphocytes were studied. The PBL possessed surface immunoglobulin at a high ratio and had high syncytium-forming activity. The PBL could not be distinguished from normal PBL cytogenetically. These PBL were shown to be polyclonal cells integrating BLV-proviral DNA randomly into their cellular DNA. These properties were similar to those of PBL appearing at the stage of PL of cattle naturally infected with BLV. The BLV-proviral DNA content of PBL and transcription of viral genes increased in parallel with development of PL and decreased along with a decline of PL indicating the possibility that gene expression and activation of BLV play an important role in induction and maintenance of PL.

Animals↗