Search PubMed⌕ Search

Biomedical subjects

Yukio Nakamura

Publications and source records attributed to Yukio Nakamura.

At least 37 records · Page 2Linked to original sources
PubMed2005

Rebamipide significantly inhibits indomethacin-induced mitochondrial damage, lipid peroxidation, and apoptosis in gastric epithelial RGM-1 cells.

Nonsteroidal antiinflammatory drugs (NSAIDs) cause complications such as gastrointestinal injury. NSAIDs were recently reported to cause mitochondrial injury: to dissipate the mitochondrial transmembrane potential (MTP), and to induce mitochondrial permeability transition pore (PTP), which liberates cytochrome c. This enzyme generates reactive oxygen species (ROS) thereby triggers caspase cascade and cellular lipid peroxidation, resulting in cellular apoptosis. However, the mechanism of this NSAID-induced MTP's role in cellular apoptosis remains unknown. Rebamipide, an antiulcer drug, is reported to scavenge ROS and to show the protective effects on indomethacin-induced tissue peroxidations. Since cytochrome c and its generation of ROS are involved in indomethacin-induced cellular apoptosis, rebamipide may attenuate mitochondrial damage. The aim of this study was to elucidate whether indomethacin induces both the MTP decrease and cellular apoptosis, and the effect of rebamipide on these phenomena. We examined the effect of rebamipide on 1) MTP change, 2) lipid peroxidation, 3) apoptosis, and 4) caspase activation using gastric mucosal epithelial cell-line treated with indomethacin. With a specially designed fluorescence analyzing microscope system, MTP change, cellular lipid peroxidation, and cellular apoptosis were investigated with the small star, filled following fluorescent dyes, MitoRed, DPPP, and Hoechst 33,258, respectively. Indomethacin treatment decreased MTP but increased both cellular lipid peroxidation and cellular apoptosis via caspase 3 and 9 activation. Rebamipide clearly inhibited these phenomena {in vitro}. We demonstrated that fluorescent dyes such as MitoRed, DPPP, and Hoechst 33,258 are useful indicators for detecting oxidative cellular injuries in living cells. Rebamipide exerts a protective effect on mitochondrial membrane stability in gastric epithelial cells.

Alanine↗
PubMed2005

Low dose fibroblast growth factor-2 (FGF-2) enhances bone morphogenetic protein-2 (BMP-2)-induced ectopic bone formation in mice.

To examine how fibroblast growth factor-2 (FGF-2) affects the BMP signaling pathway during bone morphogenetic protein-2 (BMP-2)-induced ectopic bone formation, we implanted type I collagen disks containing constant amounts of BMP-2 (5 micrograms) and varying amounts of FGF-2 onto the back muscles of adult male mice. We then performed histological analyses and histomorphometry, and measured bone mineral density and radiopaque area on the discs 1, 2, and 3 weeks after implantation. We also determined the expression profiles of several genes involved in bone formation and the BMP signaling pathway in the muscle that had been adjacent to the implanted disc and in muscle-derived primary culture cells that had similarly been treated with a constant concentration of BMP-2 and a varying concentration of FGF-2. In the presence of a constant amount of BMP-2, we confirmed that low doses of FGF-2 increased ectopic bone formation in vivo and high doses inhibited bone formation. Northern and/or Western blots of recovered muscle from the in vivo experiment and treated muscle-derived primary culture cells from the in vitro experiment revealed that low doses of FGF-2, but not high doses, increased the expression BMP receptor (BMPR)-1B, phosphorylated Smad1, Noggin, and Osteocalcin. Our results indicate that low-dose FGF-2 may facilitate BMP-2-induced ectopic bone formation by altering the expression of BMPRs on the surface of bone forming progenitor cells. They also indicate that the inhibitory effect of high-dose FGF-2 is not mediated via increased expression of the BMP inhibitor Noggin.

Animals↗
PubMed2005

Meningioma arising in Werner syndrome confirmed by mutation analysis.

OBJECTIVE AND IMPORTANCE: Meningioma arising in Werner syndrome has been described previously, but never in association with a mutation analysis. We present the first reported case of meningioma in a patient with Werner syndrome and a confirmed major mutation. In addition, we review 27 previously reported patients with meningioma associated with Werner syndrome. CLINICAL PRESENTATION: We report a 56-year-old Japanese woman with Werner syndrome and a meningioma. She presented with pain and redness of the right eye and a headache. Cranial CT revealed a tumor the in right frontal and temporal lobes. Pathological examination after surgical removal confirmed meningioma. She displayed typical features of Werner syndrome including juvenile cataract, short stature and low weight, a bird-like face, a hoarse voice, and dry, atrophic, pigmented skin. INVESTIGATION: To confirm the clinical diagnosis, a mutation analysis based on the mutant allele-specific amplification (MASA) method was performed. CONCLUSION: Mutation analysis of peripheral blood leukocyte DNA showed amplification of the mutation 4/4. There were 22 patients with Werner syndrome and meningioma reported from Japan and 5 from outside Japan. There was only one malignant meningioma. Meningiomas in Werner syndrome have a higher frequency in males and occur at a younger age than those of the general population.

Adult↗
PubMed2005

Expression profiles and functional analyses of Wnt-related genes in human joint disorders.

Rheumatoid arthritis (RA) and osteoarthritis (OA) are joint disorders that cause major public health problems. Previous studies of the etiology of RA and OA have implicated Wnt genes, although the exact nature of their involvement remains unclear. To further clarify the relationship between RA, OA, and the Wnt gene family, gene expression analyses were performed on articular cartilage, bone, and synovial tissues in knee joints taken from RA, OA, and nor-mal/control patients. Cytokine assays were also performed in cells transfected with Wnt-7b, a member of the gene family most closely linked to RA and OA. Of the human Wnt genes, real-time PCR analysis revealed significant up-regulation of Wnt-7b in OA cartilage and RA synovium. In situ hybridization and immunohistochemistry also revealed that Wnt-7b was present in articular cartilage, bone, and synovium of RA samples and in osteophytes, articular cartilage, bone marrow, and synovium of OA samples. The levels of the cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 were significantly increased in RA synovium and Wnt-7b-transfected normal synovial cells when compared with normal samples. These results point to the potential involvement of Wnt signaling in the pathobiology of both RA and OA.

Arthritis, Rheumatoid↗
PubMed2005

Efficacy of root canal preparation by Er,Cr:YSGG laser irradiation with crown-down technique in vitro.

OBJECTIVE: The purpose of this study was to compare the efficacy of Er,Cr:YSGG laser in root canal preparation and its effectiveness in removing debris and smear layer with the efficacy of the conventional hand instrument, in vitro. BACKGROUND DATA: Recently, the use of the Er,Cr:YSGG laser device in root canal preparation has been excepted in the dental clinic. However, there have been no published reports on root canal preparation by using the Er,Cr:YSGG laser irradiation. MATERIALS AND METHODS: A total of 40 straight root canals were prepared by an Er,Cr:YSGG laser at a output power of 2 W, and 40 canals were shaped by using the K file under irrigation with NaOCl and H2O2 by using the crown-down technique (control). The achievement degree of root canal preparation and debris score was morphologically investigated. RESULTS: The results showed that great improvement in the cleanliness of the walls was found using the laser technique as compared with the control technique; a significant decrease in smear layer or debris was also recognized in laser-prepared canals (p < 0.01). But canal preparations with the laser device sometime result in ledge, zipped, perforation, or over-instrumentation. CONCLUSION: The results demonstrated that root canal preparations with the laser device were significantly worse than in the control group. Further development in laser device and technique are required to ensure its success in root canal preparation.

Anti-Infective Agents, Local↗
PubMed2005

Differentiation of human amniotic membrane cells into osteoblasts in vitro.

OBJECTIVE: Pluripotent stem cells may be exist in the human amniotic membrane (HAM). The present article was aimed at establishing HAM cell lines and investigating their differentiation into osteoblasts in vitro. METHODS: HAM cell lineswere established using routine cell culture techniques and expanded in vitro. RESULTS: HAM cells were propagated from 45 out of 50 specimens (90%) and all were maintained normal karyotypes in vitro. Alkaline phosphatase (ALP) activity and alizarin red S stain were positive for 12 out of 22 HAM cell lines (54.5%). The 22 HAM cell lines were selectedat random. CONCLUSIONS: This study demonstrates that this isolation method II was more effective for establishing cell lines which differentiate into osteoblast rather than method I.

Amnion↗
PubMed2005

Effect of endoscopic transthoracic sympathicotomy on plasma natriuretic peptide concentrations in humans.

BACKGROUND: The effects of endoscopic transthoracic sympathicotomy (ETS) on plasma natriuretic peptides concentrations in humans were examined in order to elucidate the role of the sympathetic nervous system in their regulation. METHODS AND RESULTS: Thirty-seven patients with palmar hyperhidrosis underwent ETS. Cardiac functional indices were assessed by echocardiography, and plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations were measured before and after ETS. ETS caused decreases in heart rate, mean arterial pressure, systemic vascular resistance, and increases in left ventricular (LV) end-diastolic volume, stroke index, ejection fraction, and left atrial diameter. LV end-systolic volume and cardiac index remained unchanged. Following ETS, ANP increased from 10.7+/-5.9 to 24.7+/-16.8 pg/ml (p < 0.01), and BNP increased from 5.1+/-4.2 to 19.7+/-21.5 pg/ml (p < 0.01). From the multivariate regression analysis, ETS, age and gender were determined to be significant predictors of changes in the ANP and BNP concentrations. None of the hemodynamic parameters were useful as independent predictors. CONCLUSION: The plasma concentrations of ANP and BNP increased after ETS, independent of hemodynamic changes, and apparently because of the release of the inhibitory effects of the cardiac sympathetic nerves on natriuretic peptide secretion.

Adult↗
PubMed2005

Angiotensin III as well as angiotensin II regulates water flow through aquaporins in a clam worm.

Angiotensin III has been reported to exist in various animals and tissues. The physiological role, however, is still unclear except that brain angiotensin III is a central regulator of vasopressin release. In this study, angiotensin III as well as angiotensin II enhanced an increase in body weight of clam worms of Perinereis sp. under a hypo-osmotic condition and suppressed a decrease in body weight under a hyper-osmotic condition. When clam worms were treated with tetrachloroaurate (III) after angiotensin-treatment, these enhancing and suppressive effects of the angiotensins under hypo- and hyper-osmotic conditions were inhibited. In contrast, when clam worms were pretreated with tetrachloroaurate (III) before angiotensin-treatment, these effects of angiotensins were not inhibited. Since tetrachloroaurate (III) is a representative blocker of aquaporins, these results indicate that angiotensin III as well as angiotensin II regulates water flow through aquaporins in clam worms.

Angiotensin II↗
PubMed2005

Roles of His9 (P2 subsite) and His13 (P3' subsite) in angiotensinogen for catalytic reaction of renin.

Roles of His9 (P2) and His13 (P3') of angiotensinogen for the catalytic reaction of renin were investigated using purified recombinant ovine angiotensinogen and its mutants H9Q and H13Q. The pH depended reaction of human renin with angiotensinogens of wild-type, H9Q and H13Q showed peaks at pH 6.5 and 8.5, but the altitude of each peak was different. The Vmax of the reaction between H9Q and H13Q with human renin was decreased by about 50 and 70%, respectively, in comparison to wild-type angiotensinogen, at pH 6.5. At pH 8.5, the Vmax of H9Q and H13Q was 50 and 100% of that of wild-type, respectively. At pH 6.5, it was revealed that the catalytic efficiency of renin (Vmax/Km) reduced to 20 and 60% after mutation of angiotensinogen at His9 and His13 with Gln, respectively. At pH 8.5, the catalytic efficiency decreased to 10 and 70% after these mutations, respectively. These findings, therefore, indicate that histidine residues at both P2 and P3' positions probably associate with the renin catalytic reaction for angiotensin I generation.

Amino Acid Sequence↗
PubMed2004

Solitary fibrous tumor of the pleura presenting as an aneurysm-like lesion with the strongly contrasted tumor stain by angiography.

We treated a patient with solitary fibrous tumor of the pleura (SFT) whose angiograms demonstrated its feeders and strongly contrasted tumor stain. Although no one has clearly identified the specific features of SFT on angiograms, SFT can be suspected in the clinical setting if a localized chest wall tumor presents with the feeders and strongly contrasted tumor stain shown by angiography.

Aneurysm↗
PubMed2004

Rationale for the use of combination angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker therapy in heart failure.

BACKGROUND: The present multicenter study investigated whether the combination of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB) is more beneficial for preventing left ventricular remodeling and suppressing neurohumoral factors than either ACEI or ARB alone. METHODS AND RESULTS: One hundred and six patients with mild-to-moderate congestive heart failure treated in 26 Japanese institutes were randomly assigned to the combination therapy or monotherapy. Changes in physical activity (New York Heart Association functional classes, Specific Activity Scale (SAS)), concentrations of neurohumoral factors (plasma renin activity, angiotensin II, aldosterone, and brain natriuretic peptide (BNP)), and cardiac function for 6 months were compared between the 2 groups. It was found that the combination therapy, which was administered at doses standard in Japan, increased the SAS score (4.5 +/- 1.5 to 4.9 +/- 1.5, p<0.05) and decreased the plasma BNP concentration (183 +/- 163 to 135 +/- 118 pg/ml, p<0.05). In contrast, there were no changes in SAS score (4.5 +/- 1.4 to 4.6 +/- 1.4, NS) or BNP concentration (156 +/- 157 to 151 +/- 185 pg/ml, NS) in the patients receiving monotherapy. CONCLUSIONS: The results of the study demonstrate that the combination therapy, even at the standard doses for Japan, improves physical activity and plasma BNP concentration more than the monotherapy. A larger study is required to assess the effects of the combination therapy on major clinical outcomes.

Adrenergic beta-Antagonists↗
PubMed2004

A simple and efficient cryopreservation method for primate embryonic stem cells.

Human embryonic stem (ES) cells have the potential to differentiate into all cell types. As these cells may be able to provide an unlimited cell source for transplantation therapies, it is necessary to establish reliable methods for their handling and manipulation, including human ES cell cryopreservation. Here, we report the development of a simple and efficient cryopreservation method for primate ES cell lines using vitrification in conventional cryovials. Using standard slow-rate cooling methods, the cryopreservation efficiency for cynomolgus monkey ES cell lines was approximately 0.4%, while that for a human ES cell line was virtually 0%. Primate ES cell lines, however, were successfully cryopreserved by the present vitrification method using conventional cryovials yielding a survival rate of about 6.5% for monkey ES cells and 12.2% for human ES cells. Vitrified ES cells quickly recovered after thawing and exhibited a morphology indistinguishable from non-vitrified cells. In addition, they retained a normal karyotype and continued to express ES cell markers after thawing. Thus, our vitrification ES cell cryopreservation method expands the utility of primate ES cells for various research and clinical purposes.

Animals↗
PubMed2004

Autologous bone marrow stromal cell transplantation for repair of full-thickness articular cartilage defects in human patellae: two case reports.

This study assessed the effectiveness of autologous bone marrow stromal cell transplantation for the repair of full-thickness articular cartilage defects in the patellae of a 26-year-old female and a 44-year-old male. These two patients presented in our clinic because their knee pain prevented them from walking normally. After thorough examination, we concluded that the knee pain was due to the injured articular cartilage and decided to repair the defect with bone marrow stromal cell transplantation. Three weeks before transplantation, bone marrow was aspirated from the iliac crest of each patient. After erythrocytes had been removed by use of dextran, the remaining nucleated cells were placed in culture. When the attached cells reached subconfluence, they were passaged to expand in culture. Adherent cells were subsequently collected, embedded in a collagen gel, transplanted into the articular cartilage defect in the patellae, and covered with autologous periosteum. Six months after transplantation, clinical symptoms (pain and walking ability) had improved significantly and the improvement has remained in effect (5 years and 9 months posttransplantation in one case, and 4 years in the other), and both patients have been satisfied with the outcome. As early as 2 months after transplantation, the defects were covered with tissue that showed slight metachromatic staining. Two years after the first and 1 year after the second transplantation, arthroscopy was performed and the defects were repaired with fibrocartilage. Results indicate autologous bone marrow stromal cell transplantation is an effective approach in promoting the repair of articular cartilage defects.

Adult↗
PubMed2004

Embryonic stem cells form articular cartilage, not teratomas, in osteochondral defects of rat joints.

Embryonic stem (ES) cells are considered to be a potential tool for repairing articular cartilage defects, but so far it has been impossible to cause these cells to differentiate into chondrocytes exclusively, either in vivo or in vitro. To explore a potential new cell source of cell transplantation for articular cartilage defects, we transplanted ES cells into articular cartilage defects in immunosuppressed rats. ES cells (AB2.2 or CCE cells) were transplanted into articular cartilage defects in the patellar groove of immunosuppressed rats treated with cyclosporine. The cells were histologically observed until 8 weeks after transplantation. To determine whether the repair tissue in the defect in the AB2.2-transplanted group was derived from the transplanted cells, the neomycin-resistant gene, which had been transfected into AB2.2 cells but does not exist in rat cells, was used for detection. The cells produced cartilage, resulting in repair of the defects from 4 weeks until 8 weeks after the transplantation without forming any teratomas. The neomycin-resistant gene was detected in every sample, demonstrating that the repair tissue in the AB2.2-transplanted group was derived from the transplanted AB2.2 cells. The environment of osteochondral defects is chondrogenic for ES cells. ES cells may thus be a potential tool for repairing articular cartilage defects.

Animals↗
PubMed2003

Erythropoietin regulates tumour growth of human malignancies.

In addition to the chief function of erythropoietin (Epo) in promoting erythropoiesis, some other roles have been found in the brain and uterus. We have reported that signalling pathways of Epo and Epo receptor (EpoR) are involved in the tumourigenesis of ovarian and uterine cancers. To determine whether Epo plays a similar role in other malignancies, we studied the expression of Epo in several malignant human cell lines. We found that 24 malignant human cell lines examined express Epo and EpoR regardless of their origins, types, genetic characteristics and biological properties and secrete a very small amount of Epo individually and that most of them respond to hypoxic stimuli by enhanced secretion of Epo. To determine whether the Epo-EpoR pathway operates in tumours of these cell lines, we transplanted several cell lines into nude mice and confirmed the presence of Epo-responsive sites in xenografts in which the phosphorylation of the STAT5 (signal transducer and activator of transcription) is detectable. Furthermore, in nude mice we blocked the Epo signalling in xenografts of two representative cell lines, stomach choriocarcinoma and melanoma, by i.p. injections of EpoR antagonist and found inhibition of angiogenesis and survival of tumour cells leading to destruction of tumour masses and disturbances of phosphorylation of STAT5. In contrast, Epo mimetic peptide promotes angiogenesis and tumour cell survival. These findings suggest that Epo is indispensable for the growth and viability of malignant tumour and also that the deprivation of Epo signalling may be a promising therapy for human malignancy.

Cell Division↗
PubMed2003

Successful multilineage engraftment of human cord blood cells in pigs after in utero transplantation.

BACKGROUND: Successful engraftment of human hematopoietic stem and progenitor cells (HSPCs) in a large animal may serve not only as a model to study human hematopoiesis but also as a bioreactor to expand human HSPCs in vivo. The aim of this study was to accomplish xenotransplantation of human HSPCs into pig. METHODS: Total mononuclear or CD34-positive HSPCs obtained from human cord blood were xenotransplanted percutaneously under an ultrasonographic guidance into preimmune pig fetuses. Peripheral blood and bone marrow (BM) cells of recipient pigs were collected and analyzed for the presence of human cells by a polymerase chain reaction to detect human specific Alu sequence on DNA extracted from those cells. Fluorescence-activated cell sorting (FACS) analysis was also performed to detect human hematopoietic cells. RESULTS: Transplantation of human cord blood cells into pig fetuses aged less than 52 days postcoitus resulted in a good engraftment rate. In one case, engraftment was detected up to 315 days posttransplantation by polymerase chain reaction. Human hematopoietic cells were detectable also by FACS in peripheral blood and BM. Furthermore, human CD34+ HSPCs were also observed in the BM of recipients. Those CD34+ cells in BM were sorted by FACS and subjected to further analyses. First, in vitro colony formation assay resulted in formations of multilineage colonies. Second, when they were transplanted into an immunodeficient mouse they were engrafted in the mouse. CONCLUSIONS: These data indicate an engraftment of human HSPCs in pig BM. In utero transplantation of human HSPCs into a preimmune pig fetus is useful to establish a pig reproducing human hematopoiesis.

Animals↗
PubMed2003

Human prorenin has "gate and handle" regions for its non-proteolytic activation.

We investigated the mechanism for non-proteolytic activation of human prorenin using five kinds of antibodies. Each of the antigens, L1PPTDTTTFKRI11P, T7PFKRIFLKRMP17P, I11PFLKRMPSIRESLKER26P, M16PPSIRESLKER26P, and G27PVDMARLGPEWSQPM41P, was designed from the tertiary structure of predicted prorenin. These antibodies were labeled anti-01/06, anti-07/10, anti-11/26, anti-16/26, and anti-27/41, respectively, for their binding specificities. Inactive recombinant human prorenin (0.1 nM) bound to various concentrations of anti-01/06, anti-11/26, and anti-27/41 antibodies at 4 degrees C with equilibrium dissociation constants of 138, 41, and 22 nM, respectively. However, intact prorenin (0.1 nM) did not show significant binding to 200 nM anti-07/10 and anti-16/26 antibodies for 20 h. Ninety percent of prorenin (0.1 nM) was found to be non-proteolytically activated by incubation with anti-11/26 antibodies (200 nM) at 4 degrees C for 20 h. Prorenin was not active even under complex with either anti-01/06 or anti-27/41 antibodies. Prorenin was also reversibly activated at pH 3.3 and 4 degrees C for 25 h. The acid-activated prorenin bound to anti-07/10 and anti-16/26 antibodies as well as to anti-01/06, anti-11/15, and anti-27/41 antibodies at neutral pH and 4 degrees C in 2 h. Their dissociation constants were 13, 40, 8.6, 3.6, and 14 nM, respectively. The acid-activated prorenin was re-inactivated by incubation at pH 7.4 and 4 degrees C in 50 h. Anti-07/10 and anti-11/26 antibodies inhibited such re-inactivation at 25 degrees C by more than 90% and 50%, respectively, whereas other kinds of antibodies did not prevent the re-inactivation at 25 degrees C. These results indicate that prorenin has "gate" (T7PFKR10P) and "handle" (I11PFLKR15P) regions critical for its non-proteolytic activation.

Amino Acid Sequence↗