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Biomedical subjects

R Ohta

Publications and source records attributed to R Ohta.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of the mutagenic potential of ubidecarenone using three short-term assays.

Addition of ubidecarenone, coenzyme Q(10) (CoQ(10)), to foods has been proposed for its nutritive value. Ubidecarenone is present naturally in a number of foods, including meats (e.g., beef, chicken) and fish (e.g., herring, rainbow trout), and on average, people are estimated to consume 2-20 mg/day of this metabolically important substance. Currently, relatively little formal evidence regarding the safety of ubidecarenone has been identified in the toxicology literature, despite its consumption by humans for centuries without reported notable adverse effects. As such, a series of toxicological studies, including mouse bone marrow micronucleus, chromosomal aberration, and bacterial reverse mutation tests, were conducted to evaluate the in vivo and in vitro mutagenic potential of CoQ(10). The test article, ubidecarenone, was devoid of clastogenic activity when administered orally to mice at doses up to 2000 mg/kg/day. In addition, the test article did not induce chromosomal aberration in CHL/IU cells exposed to concentrations as great as 5.0 mg/ml, nor did it induce reverse mutations in Salmonella typhimurium and Escherichia coli at concentrations as great as 5000 microg/plate.

Animals↗
PubMed2004

Minor involvement of somatic growth in the onset of puberty of Hatano high- and low-avoidance rats.

The present study was planned to examine the effects of somatic growth on the determination of timing of puberty using Hatano high- and low-avoidance rats (HAAs and LAAs); the rats were genetically selected from Sprague-Dawley (SD) rats for good or poor performance in a two-way active avoidance-learning test. Since these two lines were found to have different characteristics, such as body weight at birth, maternal care and timing of male puberty, the present study characterized female puberty in Hatano rats and then compared postnatal growth and timing of puberty between the two lines of rats when they were nursed by foster SD dams. When nursed under biological dams, HAAs became heavier, exhibited vaginal opening at a younger age and first ovulation was accompanied by more oocytes than LAAs. In all of the HAAs, but none of the LAAs, ovulation was induced by a single s.c. injection of 5 IU equine chorionic gonadotropin (eCG) on day 22 after birth. An additional treatment with 10 IU human CG revealed that, in the ovaries of LAAs, a small number of follicles had developed to an ovulable stage as a result of the treatment. The fostering improved somatic growth, and weights of LAAs were sustained at a heavier level than those of fostered HAAs. The fostering, however, did not eliminate the line difference in the timing of puberty of both sexes; it did accelerate the vaginal opening of LAAs but not the balanopreputial separation. Thus, there is a phenotypic difference in the timing of female puberty in Hatano rats exhibiting a different timing of ovarian development in response to gonadotropin. The present study indicates that postnatal somatic growth is not the predominant determinant in the onset of puberty in Hatano rats.

Animals↗
PubMed2004

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats.

The high- and low-avoidance animal (HAA and LAA respectively) strains of Hatano rats were originally selected and bred from Sprague-Dawley rats for their performance in the shuttle-box task. The present study focused on the activity of the hypothalamo-pituitary-adrenocortical (HPA) axis of HAA and LAA rats in response to restraint stress. The restraint stress induced an elevation in plasma concentrations of ACTH, prolactin, corticosterone and progesterone. Peak levels of plasma ACTH during stress conditions were significantly higher in HAA rats than in LAA rats, while peak levels of prolactin were significantly lower in HAA rats than in LAA rats. Under stress conditions, ACTH and prolactin synthesis in the anterior pituitary glands was significantly higher in HAA rats compared with LAA rats. The peak plasma concentrations of corticosterone, during restraint stress, were significantly higher in LAA rats compared with HAA rats. These results indicate that the response of the hypothalamo-pituitary axis to acute restraint stress is greater in HAA rats than in LAA rats, whereas the ACTH-induced adrenal response of corticosterone release is higher in LAA rats than in HAA rats. On the other hand, prolactin secretory activity is higher in LAA rats compared with HAA rats. These differences in endocrine responses to stress may be involved in the regulation of the avoidance responses in the shuttle-box task.

Adrenocorticotropic Hormone↗
PubMed2004

Endocrinological responses during suckling in Hatano high- and low-avoidance rats.

Hatano high-avoidance (HAA) and low-avoidance (LAA) animals were originally selected from Sprague-Dawley rats for good and poor active avoidance learning in a shuttle box. We studied the endocrinological profile in lactating rats to determine the effect of suckling during mid-lactation in HAA and LAA rats. The pups were separated from their mother rats 6 h before the onset of suckling and blood samples were drawn from unanaesthetized mother rats via a jugular cannula at 0, 5 and 15 min after the suckling stimulus and then 15, 45 and 105 min after pups were removed. Plasma concentrations of oxytocin in HAA rats were significantly higher than in LAA rats during the suckling period. Plasma concentrations of prolactin and ACTH in HAA rats were significantly higher than in LAA rats during the suckling period, and at 15 min and 45 min after the pups were removed. However, there were no strain differences in circulating corticosterone between the two lines, indicating that the response of the hypothalamo-pituitary axis to the suckling stimulus was greater in HAA rats than in LAA rats, whereas the ACTH-induced adrenal response of corticosterone release was higher in LAA rats than in HAA rats. Since dopamine from the median eminence inhibits prolactin secretion from the lactotrophs of the anterior pituitary, and tuberoinfundibular dopaminergic neurones are partially regulated by the level of circulating prolactin, we evaluated the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine biosynthesis. TH, measured by the accumulation of 3,4-dihydroxyphenylalanine, was significantly higher in HAA rats than in LAA rats before the suckling stimulus. After the suckling stimulus, TH activity in HAA rats was significantly lower than before suckling, whereas TH activity in LAA rats was not changed. These findings clearly demonstrated that apparent differences between the two Hatano lines exist in endocrinological profiles during suckling. These strain differences probably originate from neurotransmitter changes, such as dopamine.

Adrenocorticotropic Hormone↗
PubMed2003

Effects of reduction of the number of primordial follicles on follicular development to achieve puberty in female rats.

Effects of reduction of the number of primordial follicles on follicular development and concentrations of circulating hormones were examined in immature female rat offspring of dams given busulfan intraperitoneally on day 14 of gestation. The offspring of dams treated with 5 mg busulfan kg(-1) showed vaginal opening at an age comparable with the offspring of dams treated with 2.5 mg busulfan kg(-1) or with corn oil as a control, although they exhibited an irregular oestrous cycle until week 14 after birth. The serum concentrations of immunoreactive inhibin and FSH on day 26 after birth of the offspring treated with 5 mg busulfan kg(-1) were similar to those of age-matched controls. On day 15 after birth, however, the concentration of their immunoreactive inhibin was markedly lower than that of controls, whereas the concentration of their FSH was increased inversely. Comparison of the numbers of ovarian follicles in the controls and groups treated with 2.5 mg busulfan kg(-1) and 5 mg busulfan kg(-1) revealed that prenatal treatment with busulfan reduced the number of follicles in the primordial or primary phase and in the preantral phase on day 7 after birth. Although the increase of the ratio of the number of preantral follicles during days 7-13 after birth tended to vary with the prenatal dose of busulfan, the number of preantral follicles in the group treated with 5 mg busulfan kg(-1) was still smaller than in the controls. The concentration of serum immunoreactive inhibin of the offspring treated with busulfan was reduced on day 7 after birth without alteration of the concentration of gonadotrophin. On day 13 after birth, the concentration of serum immunoreactive inhibin was reduced only in the offspring treated with 5 mg busulfan kg(-1), and the concentration of serum FSH of the offspring was increased inversely as found on day 15 after birth. These results indicate that a reduction in the number of primordial follicles decreases the number of follicles that enter the growing phase, a major source of circulating inhibin in the neonatal and infantile ovary, and that consequently increased circulating FSH may accelerate follicular development to achieve puberty.

Alkylating Agents↗
PubMed2001

Beneficial effects of 3-dimensional visualization on hepatic vein reconstruction in living donor liver transplantation using right lobe graft.

BACKGROUND: Recently, virtual operation planning and navigation systems have been introduced in the field of neurosurgery and orthopedic surgery. We report here the beneficial effects of 3-dimensional (3D) visualization on hepatic venous reconstruction in living donor liver transplantation (LDLT) using right lobe graft. METHODS: 3D-image reconstruction of the liver was rendered with 3-mm slices of helical computed tomography (CT) data using zioM900 (Zio Software Inc., Tokyo, Japan). To understand the anatomy of the donor's vessels and design an operation plan, a picture of the vessels in and around the liver was reconstructed. RESULTS: The 3D image demonstrated two short hepatic veins next to the inferior right hepatic vein (IRHV) as well as a large IRHV. The 3D image showed a more precise diameter of the right hepatic vein (RHV) and the IRHV and a more accurate distance between the two hepatic veins than did images measured by 2-dimensional CT. This preoperative information allowed the donor surgeon to dissect the inferior vena cava (IVC) and hepatic veins with reduced blood loss because of reduced risk of injury to the blood vessels. The 3D image revealed that both the RHV and the IRHV branched off at the same angle from the cylindrical IVC. Preoperative planning based on this information secured smooth anastomosis. CONCLUSIONS: 3D visualization is useful for hepatic venous reconstruction of the recipient as well as for donor surgery in LDLT using right lobe graft.

Female↗
PubMed2001

Experimental study of a type 3 phosphodiesterase inhibitor on liver graft function.

BACKGROUND: The number of liver transplant recipients is increasing but donor organ shortages have become more severe. The effect of milrinone, a type 3 phosphodiesterase inhibitor (PDEI), on non-heart-beating donor grafts was evaluated using an orthotopic liver transplantation model in rats. METHODS: Type 3 PDEI or normal saline (control group) was given intravenously to the donor animals for 60 min continuously (50 microg kg-1 min-1 ) before 60 min of warm ischaemia followed by cold preservation and subsequent transplantation. Survival, serum chemistry, bile output, histopathological findings and tissue cyclic 3',5'-adenosine monophosphate (cAMP) concentrations were then compared. RESULTS: Five of seven animals in the PDEI group were alive at 7 days, compared with only one of seven rats in the control group (P < 0.01). Serum levels of alanine aminotransferase 2 and 6 h after reperfusion, and hyaluronic acid levels 6 h after reperfusion, were significantly lower in the PDEI group than in the control group. Bile output from the transplanted graft was significantly greater in the PDEI group than in controls 2 h after reperfusion (P < 0.01). The mean necrotic area 6 h after reperfusion was also reduced in the PDEI-treated grafts (P < 0.01). cAMP levels in liver tissue at the end of both warm and cold ischaemia, and 2 and 6 h after reperfusion, were significantly higher in the PDEI group compared with those in the control group. CONCLUSION: Type 3 PDEI attenuated the graft injury caused by warm and cold ischaemia and subsequent reperfusion injury via an increase in intracellular cAMP levels. This treatment may be a novel pharmacological intervention for safe and efficient usage of liver grafts from non-heart-beating donors.

Animals↗
PubMed2001

Characterization of glycosylphosphatidylinositol-anchored decay accelerating factor (GPI-DAF) and transmembrane DAF gene expression in wild-type and GPI-DAF gene knockout mice using polyclonal and monoclonal antibodies with dual or single specificity.

Decay-accelerating factor (DAF, CD55) is a glycosylphosphatidylinositol (GPI)-linked membrane inhibitor of complement activation. While human and other mammalian species contain only one DAF gene, two distinct DAF genes, referred to as GPI-DAF and transmembrane (TM)-DAF, respectively, have been identified in the mouse. Using several independently generated monoclonal and polyclonal antibodies, either with dual or single specificity for GPI-DAF and TM-DAF gene products, we have examined the expression of the two DAF genes in tissues of the wild-type and a strain of knockout mouse whose GPI-DAF gene has been inactivated. By fluorescence-activated cell sorting (FACS) analysis, we found that DAF protein is present on the wild-type mouse erythrocytes and lymphocytes but no signal was detectable on the same cells of GPI-DAF gene knockout mice. Both T and B lymphocytes and splenic macrophages express the GPI-DAF gene but the expression level is higher on B lymphocytes than on T lymphocytes. Within the T cell population, both CD4+ and CD8+ T cells are positive. DAF protein was detected by immunohistochemistry at high levels on wild-type mouse spermatids and mature sperm. In contrast, only mature sperm stained positive in the GPI-DAF gene knockout mouse testis, suggesting that GPI-DAF but not the TM-DAF gene is expressed on spermatids. Examination of the fetoplacental unit at the day 7.5 stage revealed that GPI-DAF but not the TM-DAF gene is expressed in the maternal decidua cells surrounding the trophoectoderm of the embryo. No DAF expression was detected on trophoblast or the embryo proper. These findings suggest that although the TM-DAF gene is irrelevant on mouse blood cells, the two DAF genes may have different roles in germ cell development and/or mature sperm function. Because complement receptor 1-related gene/protein y (Crry) has been shown to be expressed on early mouse embryos, the complete lack of GPI-DAF and TM-DAF gene expression in early mouse development may explain the observed sensitivity of Crry-deficient embryos to maternal complement attack.

Animals↗
PubMed2001

Tissue distribution of products of the mouse decay-accelerating factor (DAF) genes. Exploitation of a Daf1 knock-out mouse and site-specific monoclonal antibodies.

Decay-accelerating factor (DAF) is a membrane regulator of C3 activation that protects self cells from autologous complement attack. In humans, DAF is uniformly expressed as a glycosylphosphatidylinositol (GPI)-anchored molecule. In mice, both GPI-anchored and transmembrane-anchored DAF proteins are produced, each of which can be derived from two different genes (Daf1 and Daf2). In this report, we describe a Daf1 gene knock-out mouse arising as the first product of a strategy for targeting one or both Daf genes. As part of the work, we characterize recently described monoclonal antibodies against murine DAF protein using deletion mutants synthesized in yeast, and then employ the monoclonal antibodies in conjunction with wild-type and the Daf1 knock-out mice to determine the tissue distribution of the mouse Daf1 and Daf2 gene products. To enhance the immunohistochemical detection of murine DAF protein, we utilized the sensitive tyramide fluorescence method. In wild-type mice, we found strong DAF labelling of glomeruli, airway and gut epithelium, the spleen, vascular endothelium throughout all tissues, and seminiferous tubules of the testis. In Daf1 knock-out mice, DAF labelling was ablated in most tissues, but strong labelling of the testis and splenic dendritic cells remained. In both sites, reverse transcription-polymerase chain reaction analyses identified both GPI and transmembrane forms of Daf2 gene-derived protein. The results have relevance for studies of in vivo murine DAF function and of murine DAF structure.

Animals↗
PubMed2000

Expression of Bra r 1 gene in transgenic tobacco and Bra r 1 promoter activity in pollen of various plant species.

Bra r 1 encodes a Ca2+-binding protein specifically expressed in anthers of Brassica rapa. In this study, we isolated a genomic clone of Bra r 1 and found sequences similar to Pollen Box core motifs and LAT56/59 box, pollen-specific cis-acting element, in the 5' upstream region of Bra r 1. Reporter gene fusion revealed that the Bra r 1 promoter directs male gametophytic expression in Nicotiana tabacum, Arabidopsis thaliana and B. napus, showing strong expression in mature pollen grains similar to that of endogenous Bra r 1. Genomic DNA of Bra r 1 was introduced into tobacco plants and the highest accumulation of Bra r 1 protein was observed in mature pollen in the same manner as reporter gene expression. Using in vitro-germinated pollen tubes of transgenic tobacco, we firstly demonstrated the subcellular localization of Bra r 1 in pollen tubes. Bra r 1 protein was distributed throughout the pollen tube of transgenic tobacco and slightly intense signals of Bra r 1 were observed in the tip region. In long-germinated pollen tubes, Bra r 1 was detected only in the cytoplasmic compartments while no signals were observed in the empty part of the pollen tube, indicating that cytoplasmic movement toward the tube tip is accompanied by Bra r 1. Hence, we suggest that Bra r 1 is involved in pollen germination and pollen tube growth.

Amino Acid Sequence↗
PubMed2000

A novel auxiliary partial orthotopic liver transplantation model in rats.

BACKGROUND: Although auxiliary partial orthotopic liver transplantation (APOLT) has become a well-accepted procedure recently, a practical experiment model in APOLT using small animals has yet to be developed. METHODS: Male Lewis rats were used for both donors and recipients. An auxiliary partial graft was obtained by ex vivo resection of the donor right and caudate lobes, and was transplanted orthotopically into the recipient after resection of the recipient medial and left hepatic lobes. Portal vein and hepatic duct reconstructions were by the cuff technique, and supra- and intrahepatic vena cava were sutured continuously. Operative outcomes, serum chemistry, liver tissue blood flow, angiographic and histopathological findings were then examined. Conventional orthotopic liver transplantation (OLT) procedures were also undertaken as a control. RESULTS: One-day, 1-week and 1-month survival rate of APOLT group was 100, 85 and 85%, respectively. AST in the APOLT group on the 1st postoperative day was significantly higher than in the OLT group. No significant differences were recognized in serum albumin and total bilirubin levels between the two groups. Although the portogram of an APOLT rat showed slight narrowing at the cuff anastomosis site, both the graft and the native liver were opacified similarly. The liver tissue blood flow on the 5th postoperative day in the native liver and the graft returned to as high as 95 and 74% of the values on laparotomy, respectively. Histological examinations of the auxiliary graft 1 month after transplantation showed mild ductular proliferation and mononuclear cell infiltration around the portal triads. CONCLUSION: This novel APOLT model in rats allows practical and reproducible results, and may be of value in the basic study of APOLT procedures.

Angiography↗
PubMed2000

[Living donor liver transplantation in Kyushu University].

We performed living donor liver transplantation (LDLT) for 40 patients at Kyushu University Hospital, Fukuoka Japan during the period from October 1996 to April 2000. The patients consisted of 32 adults and 8 children with a mean age of 35.8 years (range: 1 year and 10 months to 65 years old). The underlying liver diseases of the 40 patients included the fulminant hepatic failure (n = 14), biliary atresia (n = 7), liver cirrhosis (HCV) (n = 6), primary biliary cirrhosis (n = 5), primary sclerosing cholangitis (n = 2), familiar amyloidotic polyneuropathy (n = 2), Alagille syndrome (n = 1), glycogen storage disease (n = 1), huge hepatic hemangiomas (n = 1), and Wilson's disease (n = 1). All liver grafts were obtained from each patient's family members except for one domino transplant donor's case, comprised of 13 parents, 13 sons and daughters, 11 brothers and sisters, and 3 wives. The donors are presently all doing well. The patient survival rate is presently 92.5%.

Adolescent↗
PubMed1999

Structural basis for the regulation of UDP-N-acetyl-alpha-D-galactosamine: polypeptide N-acetylgalactosaminyl transferase-3 gene expression in adenocarcinoma cells.

The UDP-N-acetyl-alpha-D-galactosamine: polypeptide N-acetylgalactosaminyl transferase-3 (Gal NAc-T3) gene, a member of the Gal NAc transferase gene family, is expressed in a tissue-specific manner. To elucidate the function of this gene, we have focused on the molecular mechanism underlying regulation of gene expression. We have cloned Gal NAc-T3 cDNA and used it to show that Gal NAc-T3 mRNA is expressed in tumor cell lines derived from secretory epithelial tissue adenocarcinomas but not in cell lines derived from bladder and epidermoid carcinomas. Using a polyclonal antibody to Gal NAc-T3, we observed protein expression in adenocarcinoma but not non-adenocarcinoma cell lines, and in breast carcinoma cells but not in normal breast tissue. We used Gal NAc-T3 cDNA to isolate three overlapping genomic clones containing the 5'-portion of the human Gal NAc-T3 gene, and we sequenced 1.6 kb around the first exon. A transient expression assay using the luciferase gene showed that promoter activity was much higher in MCF-7 cells than in KB cells. In vivo footprint experiments showed significant protection of a distal GC box, an NRF-1 site, and an AP-2 site in MCF-7 cells. A novel stem and loop structure extending from nucleotide -103 to nucleotide -165 and contiguous to these transcription factor binding sites seemed to be functional in regulating Gal NAc-T3 gene transcription, and a KMnO4 footprint experiment showed that this stem and loop structure could be formed in vivo. We also observed dimethyl sulfate hypersensitive sites in the untranslated region around nucleotide +50 in MCF-7 but not in KB cells. These findings indicate that Gal NAc-T3 gene expression is regulated by multiple systems, including transcription factor binding sites and a stem-and-loop structure, and that this regulation is restricted to cell lines derived from epithelial gland adenocarcinomas but not cells derived from nonsecretory epithelial tissue carcinomas. In addition, our immunohistochemical results suggest that our anti-Gal NAc-T3 antibody may be useful for diagnostic purposes in the early stages of breast cancer.

Adenocarcinoma↗
PubMed1999

Plasma ACTH levels during early, two-way avoidance acquisition in high- and low-avoidance rats (Hatano strains).

Having successfully bred for high- and low-avoidance rats (HAA and LAA, respectively) on a shuttlebox task, we performed three experiments designed to identify factors which might be related to the phenotypic differences seen in avoidance behavior. In experiment 1, shuttlebox behavior was measured to determine whether the phenotypic difference was activity related. In terms of intertrial responses, there was no difference between HAA and LAA rats in locomotor activity during the conditioning process. Experiment 2 compared adrenal weights of HAA and LAA rats at 11 weeks of age. The observation that the adrenal glands were heavier in HAA than in LAA rats suggested that these strains might differ in aspects of endocrine response. In experiment 3, plasma levels of ACTH and corticosterone were determined during early escape/avoidance acquisition in the shuttlebox. Plasma levels of ACTH after the shuttlebox testing were higher in HAA than in LAA rats. There was no difference between the two strains in plasma levels of corticosterone after testing, possibly due to a ceiling effect. These results suggest that the phenotypic differences in the acquisition of avoidance behavior of HAA and LAA rats may be related to different endocrine responses, rather than to locomotor activity.

Adrenal Glands↗
PubMed1999

Characterization of mouse DAF on transfectant cells using monoclonal antibodies which recognize different epitopes.

Several membrane proteins prevent host cells from homologous complement attack. In humans, one such protein, decay-accelerating factor (DAF), exists as two isoforms, a GPI anchored form and a secreted form, which are generated by alternative splicing. DAF in mouse is also expressed as two isoforms, a GPI anchored form (GPI-DAF) and a transmembrane form (TM-DAF), which are produced from two separate genes. In this study, we transfected cDNA of mouse GPI-DAF or TM-DAF into Chinese hamster ovary (CHO) cells. Both isoforms of DAF on CHO cells were shown to regulate mouse complement C3 deposition mediated by the classical and alternative pathways and the inhibitory activity of both isoforms was species restricted. The two mouse DAF isoforms were effective against rat complement but not against human and guinea pig complement. Furthermore, we produced hamster mAbs to mouse DAF using GPI-DAF transfectant cells and established seven unique mAbs (RIKO-1-7). Western blotting analysis using RIKO-3, which reacts with both GPI-DAF and TM-DAF, and RIKO-4, which is an anti-GPI-DAF specific mAb, indicated that GPI-DAF was expressed on erythrocytes, spleen and testis, and that TM-DAF was expressed only in testis.

Animals↗
PubMed1999

An organosulfur compound isolated from oil-macerated garlic extract, and its antimicrobial effect.

An organosulfur compound was isolated from oil-macerated garlic extract by silica gel column chromatography and preparative TLC. From the results of NMR, IR, and MS analyses, its structure was determined as E-4,5,9-trithiadeca-1,7-diene-9-oxide (iso-E-10-devinylajoene, iso-E-10-DA). This compound was different from E-4,5,9-trithiadeca-1,6-diene-9-oxide (E-10-devinylajoene, E-10-DA) only in the position of a double bond. Iso-E-10-DA had antimicrobial activity against Gram-positive bacteria, such as Bacillus cereus, B. subtilis, and Staphylococcus aureus, and yeasts at the concentration lower than 100 micrograms/ml, but Gram-negative bacteria were not inhibited at the same concentration. The antimicrobial activity of iso-E-10-DA was inferior to those of similar oil-macerated garlic extract compounds such as E-ajoene, Z-ajoene, and Z-10-DA. From these results, it was suggested that trans structure and/or the position of double bond of iso-E-10-DA reduce the antimicrobial activity.

Anti-Bacterial Agents↗