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Biomedical subjects

K Muraoka

Publications and source records attributed to K Muraoka.

At least 19 recordsLinked to original sources
PubMed2006

The high integration and differentiation potential of autologous neural stem cell transplantation compared with allogeneic transplantation in adult rat hippocampus.

Cell therapy is thought to have a central role in restorative therapy, which aims to restore function to the damaged nervous system. The purpose of this study was to establish an autologous neural stem cell (NSC) transplantation model using adult rats and to compare survival, migration, and differentiation between this system and allogeneic NSC transplantation. Furthermore, we compared the immunologic response of the host tissue between autologous and allogeneic transplantation. NSCs were removed from the subventricular zone of adult Fischer 344 rats using stereotactic methods. NSCs were expanded and microinjected into normal hippocampus in the autologous brain. Allogeneic NSC (derived from adult Wistar rats) transplantation was performed using the same procedure, and hippocampal sections were analyzed immunohistologically 3 weeks post-transplantation. The cell survival and migration rate were higher for autologous transplantation than for allogeneic transplantation, and the neuronal differentiation rate in the autologous transplanted cells far exceeded that of allogeneic transplantation. Furthermore, there was less astrocyte and microglia reactivity in the host tissue of the autologous transplantation compared with allogeneic transplantation. These findings demonstrate that immunoreactivity of the host tissue strongly influences cell transplantation in the CNS as the autologous transplantation did not induce host tissue immunoreactivity; the microenvironment was essentially maintained in an optimal condition for the transplanted cells.

Animals↗
PubMed2001

Method to measure the electric field vector in an argon glow discharge using laser polarization spectroscopy.

A method for measurement of the direction of the electric field in a glow discharge is reported. This method uses the dependence of the electronic excitation spectrum of argon atoms on the polarization of the laser radiation. In this research, laser radiation was used to excite argon atoms in a plasma from the 4s [3 / 2](2) metastable level to Rydberg levels, and excitation spectra were measured using laser optogalvanic (LOG) spectroscopy. In addition, LOG spectra of argon atoms interacting with an electric field were calculated by solving the Schrödinger equation. Good agreement was found between experimental and theoretical LOG spectra obtained for different polarizations of the laser radiation.

Journal Article↗
PubMed2000

Measurement method for electric fields based on stark spectroscopy of argon atoms

We report the development of a method for the measurement of electric fields in glow discharge plasmas, based on Stark spectroscopy of argon atoms. The method is based on laser excitation of transitions in atomic argon. The key feature of the method is that the electric field is determined by matching experimentally obtained absorption spectra to theoretically calculated spectra. The dependence of the positions of energy levels of argon atoms on the strength of the electric field was calculated by solving the Schrodinger equation for the argon atom. Measurements of Stark spectra were made in the sheath region of a glow discharge using laser optogalvanic spectroscopy. The wavelength of the laser radiation was tuned to the transitions 4s-->nf (n=7,8,ellipsis,14) of the argon atom. For n=11, the lower limit for electric field measurements was estimated to be 14 V/mm.

Journal Article↗
PubMed2000

[Extragonadal germ cell tumor coexisted with renal cell carcinoma--a case report].

A patient was 31-year-old man with the chief complaint of 38 degrees C fever. He was pointed out left renal tumor by abdominal ultrasonography and computerized tomography (CT). CT revealed left infraclavicular, mediastinal and retroperitoneal lymph nodes swelling and left renal tumor. Serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (HCG-beta) level were elevated. The diagnosis of extragonadal germ cell tumor and left renal cell carcinoma was confirmed pathologically by infraclavicular lymph node and renal biopsy. He was treated with 4 courses of BEP regimen and interferon-alpha, cimetidine therapy for 2 weeks preoperatively. After serum tumor markers were normal level, he underwent left radical nephrectomy and left infraclavicular, mediastinal and retroperitoneal lymph node dissection. The histology of all lymph nodes was necrotic tissue, but operation was incomplete. Therefore VIP therapy was performed postoperatively. This is the first case of extragonadal germ cell tumor coexisted with renal cell carcinoma in the world.

Adult↗
PubMed1999

Immunosuppressant FK506 activates NF-kappaB through the proteasome-mediated degradation of IkappaBalpha. Requirement for Ikappabalpha n-terminal phosphorylation but not ubiquitination sites.

The immunosuppressant FK506 activates NF-kappaB through IkappaBalpha degradation in nonlymphoid cells. In the present study, we analyzed mechanisms by which FK506 induces IkappaBalpha degradation. We found that FK506 induces the degradation of both IkappaBalpha and IkappaBbeta and that the time courses of the FK506-induced degradation are quite different from degradation induced by interleukin 1 (IL-1). Despite this difference, FK506-induced IkappaBalpha degradation was dependent on the N-terminal Ser-32 and Ser-36 phosphorylation sites and was mediated by proteasomes, as is the case for IL-1-induced IkappaBalpha degradation. We further showed that FK506 induces weak and slow phosphorylation of IkappaBalpha at Ser-32. However, unlike IL-1-induced degradation, IKK-1 and IKK-2 were not activated significantly nor was FK506-induced IkappaBalpha degradation dependent on the N-terminal ubiquitination sites (Lys-21 and Lys-22). These results therefore indicate that FK506 and IL-1 utilize similar but distinct mechanisms to induce the phosphorylation and degradation of IkappaBalpha.

Amino Acid Sequence↗
PubMed1999

Soluble interleukin-6 (IL-6) receptor with IL-6 stimulates megakaryopoiesis from human CD34(+) cells through glycoprotein (gp)130 signaling.

We have recently shown that stimulation of glycoprotein (gp) 130, the membrane-anchored signal transducing receptor component of IL-6, by a complex of human soluble interleukin-6 receptor (sIL-6R) and IL-6 (sIL-6R/IL-6), potently stimulates the ex vivo expansion as well as erythropoiesis of human stem/progenitor cells in the presence of stem cell factor (SCF). Here we show that sIL-6R dose-dependently enhanced the generation of megakaryocytes (Mks) (IIbIIIa-positive cells) from human CD34(+) cells in serum-free suspension culture supplemented with IL-6 and SCF. The sIL-6R/IL-6 complex also synergistically acted with IL-3 and thrombopoietin (TPO) on the generation of Mks from CD34(+) cells, whereas the synergy of IL-6 alone with TPO was barely detectable. Accordingly, the addition of sIL-6R to the combination of SCF + IL-6 also supported a substantial number of Mk colonies from CD34(+) cells in serum-free methylcellulose culture, whereas SCF + IL-6 in the absence of sIL-6R rarely induced Mk colonies. The addition of monoclonal antibodies against gp130 to the suspension and clonal cultures completely abrogated the megakaryopoiesis induced by sIL-6R/IL-6 in the presence of SCF, whereas an anti-TPO antibody did not, indicating that the observed megakaryopoiesis by sIL-6R/IL-6 is a response to gp130 signaling and independent of TPO. Furthermore, human CD34(+) cells were subfractionated into two populations of IL-6R-negative (CD34(+) IL-6R-) and IL-6R-positive (CD34(+) IL-6R+) cells by fluorescence-activated cell sorting. The CD34(+) IL-6R- cells produced a number of Mks as well as Mk colonies in cultures supplemented with sIL-6R/IL-6 or TPO in the presence of SCF. In contrast, CD34(+) IL-6R+ cells generated much less Mks and lacked Mk colony forming activity under the same conditions. Collectively, the present results indicate that most of the human Mk progenitors do not express IL-6R, and that sIL-6R confers the responsiveness of human Mk progenitors to IL-6. Together with the presence of functional sIL-6R in human serum and relative unresponsiveness of human Mk progenitors to IL-6 in vitro, current results suggest that the role of IL-6 may be mainly mediated by sIL-6R, and that the gp130 signaling initiated by the sIL-6R/ IL-6 complex is involved in human megakaryopoiesis in vivo.

Antigens, CD↗
PubMed1999

Restricted diversification of T-cells in chronic active Epstein-Barr virus infection: potential inclination to T-lymphoproliferative disease.

To assess the abnormal T-cell expansion in chronic active Epstein-Barr virus infection (CAEBV), T-cell antigen receptor (TCR) repertoire was analyzed in four patients with the disease. All fulfilled the diagnostic criteria of CAEBV, presenting with fever, hepatosplenomegaly, cytopenia, abnormal high titers of anti EBV-antibodies, and positive EBV genome of unknown cause. Southern blotting probed with EBV-terminal repeats and TCR Cbeta gene indicated clonal expansion of the infected cells in 3 and 2 patients, respectively. The number of CD4+ HLA-DR+ cells appreciably increased in patients 1 (59%) and 2 (24%), who had a coronary aneurysm and central nervous system involvement, respectively. TCR gene expression examined by the inverse polymerase chain reaction methods revealed that Vbeta gene usages were preferential in all patients (Vbeta7 and Vbeta12: patient 1, Vbeta4: patient 2, Vbeta13: patients 3 and 4), compared with those in healthy controls. Valpha18 gene expression was remarkably high in patients 1 and 2. Moreover, Jbeta gene expression was skewing in the reigning Vbeta clones in all patients. Vbeta4-Jbeta1.5 and Vbeta13-Jbeta1.5 genes were clonally expressed in patients 2 and 4, respectively. These results suggest that CAEBV is associated with the restricted diversity of T-cells, which may stem from the sustained expansion of oligoclonal T-cells possibly driven by conventional viral antigens, but not, superantigens. Although the study is limited by the small number of patients, the unbalanced T-cell repertoire might contribute to the evolution of T-lymphoproliferative disease, otherwise, imply the innate defective immunity to EBV in CAEBV patients.

Adolescent↗
PubMed1999

[Examination for indication of systematic biopsy for diagnosis of prostate cancer].

BACKGROUND: Systematic biopsy has been commonly used for detection of prostate cancer. Nevertheless, as this examination occasionally gives patients severe complications it is necessary to give careful consideration for application of this examination. Thus, we analyzed retrospectively 145 cases who underwent transrectal ultrasonography (TRUS) guided systematic biopsy to evaluate the application of systematic biopsy, correlating with the findings of digital rectal examination (DRE), prostate specific antigen (PSA), the findings of transrectal ultrasonography (TRUS) and the results of biopsies. METHODS: Between May, 1995 and May, 1997, 143 patients who were suspected to have prostate cancer with either of PSA and DRE, and 2 patients who received visual laser ablation of prostate (VLAP), underwent TRUS guided systematic biopsy of prostate. We evaluated diagnostic efficacy of PSA, DRE, TRUS, prostate-volume-specific PSA, and PSA density (PSAD). RESULTS: Sensitivity, specificity and positive predictive value (P.P.V.) are 78.4%, 62.8% and 53.5% for DRE, 100.0%, 4.4% and 41.8% for PSA, 88.2%, 60.0% and 52.9% for TRUS, 87.8%, 72.1% and 64.2% for prostate-volume-specific PSA, 100.0%, 30.6% and 45.4% for PSAD, respectively. Ten of 69 patients (14.5%) whose PSA levels were 4.0 to 10.0 ng/ml were diagnosed as cancer, and positive for both or either of DRE and TRUS. Twenty-seven who were negative for both of DRE and TRUS were not diagnosed as prostate cancer. Using the combination of prostate-volume-specific PSA, DRE and TRUS, we could eliminate 29 non-cancer men (21.5%) whose PSA level was greater than 4.0 ng/ml from systematic biopsy. CONCLUSION: On the diagnosis of prostate cancer, the combination of prostate-volume-specific PSA, DRE and TRUS is very useful to exclude unnecessary systematic biopsy, if an urologist could be used to and trained for DRE and TRUS.

Aged↗
PubMed1998

Formation of retinochoroidal collaterals in central retinal vein occlusion.

PURPOSE: To demonstrate the drainage routes that compensate the venous congestion in central retinal vein occlusion. METHODS: Indocyanine green angiography was performed in 13 eyes of 13 patients with central retinal vein occlusion at the involutional stage using a scanning laser ophthalmoscope. The interval between onset of central retinal vein occlusion and indocyanine green angiography ranged from 1.0 to 9.3 years (mean, 3.6 years). Panoramic indocyanine green angiograms that covered the entire choroidal vasculature were produced by composing regional angiograms. RESULTS: Retinochoroidal collateral routes were found in 10 eyes that had papillary vascular loops. They were not observed in three eyes that did not have the vascular loops. Papillary vascular loops served as the collaterals to connect retinal veins and choroidal veins. The blood in the retinal veins was drained through the papillary vascular loops into the choroidal veins. These choroidal veins were selectively dilated and acted as drainage routes to the vortex veins. Nasal vortex veins served as extraocular exits of the drainage routes in all 10 eyes, and temporal vortex veins served as extraocular exits of the drainage routes in three of the 10 eyes. CONCLUSIONS: In central retinal vein occlusion with papillary loops, blood in the retinal veins ultimately drained into the vortex veins through the retinochoroidal collaterals.

Aged↗
PubMed1998

Reperfusion of occluded capillary beds in diabetic retinopathy.

PURPOSE: To demonstrate the reperfusion of nonperfused capillary beds in diabetic retinopathy. METHODS: In a retrospective study, we reviewed 292 fluorescein angiograms of 94 eyes of 74 patients (mean age, 52 years; range, 20 to 68 years) with diabetic retinopathy. Fluorescein angiography was performed repeatedly (mean, three times; range, two to eight times) during a mean follow-up period of 2 years (range, 3 months to 12 years). None of the 94 eyes received laser photocoagulation. RESULTS: Reperfusion of occluded capillary beds was observed in 65 (69%) of 94 eyes. Reperfusion was characterized by recanalization in 22 (34%) of the 65 eyes or by intraretinal neovascularization in 54 (83%) of the 65 eyes. The former took place in small nonperfused areas and the latter in larger nonperfused areas. Reperfusion occurred throughout the entire fundus in six of 94 eyes, resulting in resolution of diabetic retinopathy. Reperfused capillary beds with intraretinal neovascularization left vascular remodeling, which was seen as twisted or kinked abnormal vessels. CONCLUSIONS: In diabetic retinopathy, occluded capillary beds may be reperfused. Twisted abnormal vessels may represent the reperfusion process through intraretinal neovascularization.

Adult↗
PubMed1998

Radiation choroidopathy with remodeling of the choroidal venous system.

PURPOSE: To describe a case of radiation choroidopathy manifesting drastic remodeling of choroidal drainage routes. METHOD: Case report. A 34-year-old man who had received radiation treatment for a tumor in the upper eyelid of his right eye 15 years earlier had floating black spots. He was examined ophthalmologically, including with indocyanine green angiography using a scanning laser ophthalmoscope. RESULTS: The right eye manifested classic features of radiation retinopathy in the superior fundus. Indocyanine green angiography showed vaso-occlusion of choroidal arteries, capillaries, and veins in a wider area than that affected by radiation retinopathy. The superotemporal vortex vein was obliterated, resulting in a remodeling of the choroidal veins in the same quadrant. The blood in this quadrant drained into the inferotemporal vortex vein through collateral venovenous drainage routes. CONCLUSION: The diagnosis in this eye was radiation retinopathy and radiation choroidopathy. Choroidal vascular lesions were more pronounced and involved a wider area than retinal vascular lesions did. This case illustrates that the choroidal veins may manifest a vast plasticity to remodel the drainage route after obliteration of a major vortex vein.

Adult↗
PubMed1998

Retinal arteriovenous shunt at the arteriovenous crossing.

OBJECTIVE: The purpose of the study was to demonstrate that the arteriovenous shunt at the arteriovenous crossing could occur in major retinal vascular diseases other than Takayasu disease. DESIGN: Clinical review of consecutive case series. PARTICIPANTS: The authors studied 1885 eyes with retinal vascular diseases such as diabetic retinopathy, branch retinal vein occlusion, central retinal vein occlusion, central retinal artery occlusion, Leber's miliary aneurysms, Eales disease, Behçet disease, and systemic lupus erythematosus retinopathy. INTERVENTION: Fluorescein fundus angiography using a wide-field fundus camera (60 degrees) was performed. MAIN OUTCOME MEASURES: Dye transit from artery to vein through sequential angiography. RESULTS: The arteriovenous shunt at the arteriovenous crossing was found in 8 eyes with proliferative diabetic retinopathy, 27 eyes with branch retinal vein occlusion in the chronic stage, 2 eyes with central retinal vein occlusion, 2 eyes with central retinal artery occlusion, and 2 eyes with miliary aneurysms. The arteriovenous shunt was formed by a direct inflow from artery to vein, showing vasodilation and hyperpermeability, followed by obliteration peripheral to the shunts. The pattern of initial inflow was classified into axial flow and laminar flow, and the inflow became wider and more rapid in the advanced stage. CONCLUSIONS: These findings indicate that the arteriovenous shunt at the arteriovenous crossing is not a unique phenomenon in Takayasu disease but rather is a basic pattern of retinal vascular reaction pathologic states.

Adult↗
PubMed1998

Chemical synthesis of a novel aromatic amine mutagen isolated from water of the Nishitakase River in Kyoto and a possible route of its formation.

Among five mutagenic compounds isolated from water samples, taken at sites below the sewage plants of the Nishitakase River in Kyoto, Japan, the structure of compound I has been determined to be 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1). Since this novel aromatic amine mutagen has characteristic substituents in its molecule, it is postulated that the azo dye, 2-[(2-bromo-4, 6-dinitrophenyl)azo]-4-methoxy-5-[bis(2-methoxyethyl)amino]acetoanili de (AZO DYE-1), used as an industrial material, is converted to the corresponding 2-phenylbenzotriazole derivative with a reducing reagent and subsequently to PBTA-1 by chlorination. In fact, AZO DYE-1 changed to the dechlorinated derivative of PBTA-1 (deClPBTA-1) on treatment with sodium hydrosulfite, and this reacted with sodium hypochlorite to produce PBTA-1. Moreover, the presence of deClPBTA-1 was confirmed in a river water sample, along with PBTA-1. PBTA-1 showed potent mutagenic activities in Salmonella typhimurium TA98 and YG1024, inducing 88 000 and 3 000 000 revertants, respectively, per microg, with S9 mix. deClPBTA-1 was also mutagenic, but less potent. From these observations, it is suggested that PBTA-1 is produced from AZO DYE-1 through deClPBTA-1, during industrial processes at dyeing factories and the treatment of wastewater at sewage plants.

Japan↗
PubMed1998

Interferon-gamma and human megakaryopoiesis.

Interferon-gamma (IFN-gamma) exhibits various properties including antigrowth activity in neoplastic and normal cells and regulatory roles in immune responses and hematopoiesis, but studies of IFN-gamma effects on human megakaryopoiesis have been inconclusive. Recently we have used serum-free culture of purified CD34+ cells to demonstrate that IFN-gamma stimulates the proliferation of relatively mature megakaryocytic progenitors independently of thrombopoietin. It has been also shown that IFN-gamma stimulates the maturation of megakaryocytes, and has a significant synergism with stem cell factor in human megakaryopoiesis. Further studies are needed to clarify the in vivo effect of IFN-gamma on human megakaryopoiesis and the clinical relevance of IFN-gamma.

Cellular Senescence↗
PubMed1997

Synergistic action of Flt3 and gp130 signalings in human hematopoiesis.

We recently showed that c-kit signal synergizes with glycoprotein (gp)130 signal mediated by a complex of interleukin (IL)-6 and soluble IL-6 receptor (IL-6/sIL-6R) to stimulate the expansion of human primitive hematopoietic progenitor cells and erythropoietin-independent erythropoiesis. In the present study, we examined the effect of a ligand for Flt3 (FL), whose receptor tyrosine kinase is closely related to c-kit, in combination with IL-6/sIL-6R on human hematopoiesis in vitro. In serum-containing methylcellulose clonal culture of cord blood CD34(+) cells, whereas FL alone stimulated only granulocyte-macrophage (GM) colony formation, erythroid bursts and mixed colonies in addition to GM colonies were induced by FL with IL-6/sIL-6R, but not IL-6/sIL-6R alone. In suspension culture, CD34(+) cells generated a small number of myeloid cells in the presence of FL or IL-6/sIL-6R alone. However, the addition of IL-6/sIL-6R to the culture with FL induced the generation of a significant number of erythroid cells and megakaryocytes in addition to myeloid cells. The combination of FL and IL-6/sIL-6R also induced a remarkable expansion of GM colony- and erythroid burst-forming cells and multipotential progenitors, although FL or IL-6/sIL-6R alone induced the generation of only a small number of progenitors for GM colonies. The synergistic effects of FL and IL-6/sIL-6R were confirmed in serum-free clonal and suspension cultures. In addition, the addition of anti-human gp130 monoclonal antibodies abrogated the synergistic action. These results indicate that Flt3 signal, as well as c-kit signal, synergizes with gp130 signal to stimulate human myelopoiesis, erythropoiesis and megakaryopoiesis, and the expansion of primitive multipotential hematopoietic progenitor cells.

Antibodies, Monoclonal↗
PubMed1997

Hypoxia, but not reoxygenation, induces interleukin 6 gene expression through NF-kappa B activation.

Interleukin (IL) 6 is one of major mediators of inflammation, and IL-6 gene activation during hypoxia/reoxygenation has been implicated in the pathogenesis of ischemia/reperfusion injury. However, molecular events involved in IL-6 gene expression during hypoxia/reoxygenation remain to be identified. We have previously shown that NF-kappa B plays an essential and indispensable role in the transcriptional activation of the IL-6 gene induced by various stimuli, including IL-1 and tumor necrosis factor-alpha. We show here that hypoxia, but not reoxygenation, induces the activation of NF-kappa B through the degradation of a major inhibitor of NF-kappa B, I kappa B alpha. This hypoxia-induced NF-kappa B activation resulted in the kappa B-dependent transcriptional activation of the IL-6 gene. Interestingly, the time course of hypoxia-induced NF-kappa B activation was rather slow as compared with those of NF-kappa B activation induced by other stimuli, such as IL-1: a significant NF-kappa B activation was not observed before 1 hr of hypoxia treatment and persisted for up to 7 hr of hypoxia treatment. However, hypoxia-induced NF-kappa B activation was not inhibited by cycloheximide, which indicates that hypoxia directly triggers NF-kappa B activation. Furthermore, while hypoxia is unlikely to generate reactive oxygen intermediates, pretreatment of cells with antioxidants such as N-acetyl cysteine and alpha-tocopherol inhibited NF-kappa B activation induced by hypoxia. Thus, we discuss possible implications of these results for a postulated role of reactive oxygen intermediates in NF-kappa B activation.

Animals↗