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Biomedical subjects

Minoru Tanaka

Publications and source records attributed to Minoru Tanaka.

At least 19 recordsLinked to original sources
PubMed2007

Pattern VEPs before and after idiopathic epiretinal membrane removal.

Pattern visual evoked potentials (pVEPs) were used to assess the visual function before, and 1 and 6 months after removal of an idiopathic epiretinal membrane (ERM) from eight eyes. All patients underwent a standard three-port pars plana vitrectomy to remove the ERM removal and cataract surgery. pVEPs were elicited by check sizes of 15', 30', 60', and 120' with a reversal rate of 2 reversals/s. One hundred responses were averaged with an analysis time of 300 ms. The amplitude ratio (affected eye/fellow eye) of the P100 component were significantly larger at 6 months with smaller check sizes, and the increase was accompanied by an improvement of the VA. The mean peak latency of P100 did not change significantly for all check sizes. We conclude that the improvement of the P100 amplitude with smaller check sizes resulted from the recovery of visual function after the ERM removal.

Aged↗
PubMed2006

The suppressive effect of Mekabu fucoidan on an attachment of Cryptosporidium parvum oocysts to the intestinal epithelial cells in neonatal mice.

The present study was done to investigate the effects of fucoidan and de-sulfated fucoidan isolated from the sporophyll of Undaria pinnatifida on the C. parvum adhesion to the cultured human intestinal cells and on the C. parvum infection in neonatal mice. The C. parvum adhesion to human Intestinal 407 cells was significantly suppressed by a low dose (1 micro g/ml) of Mekabu fucoidan (1 micro g/ml) (approx. 20.5 oocysts, p<0.0001), but not by de-sulfated fucoidan (approx. 138.2 oocysts), as compared with that (approx. 121.0 oocysts) of phosphate-buffered saline (PBS). The in vivo experiments presented here revealed that C. parvum oocysts in the fucoidan-treated mice was reduced nearly one fifth (approx. 5.4x10(4) oocysts, p<0.02) of the total number of oocysts (approx. 3.0x10(5)) in mice treated with PBS, but no significant effect of de-sulfated fucoidan was observed. These results show that (i) fucoidan effectively inhibits the growth of C. parvum in mice; and (ii) the ester sulfate of fucoidan is an active site to prevent the adhesion of C. parvum to the intestinal epithelial cells. Finally, we concluded that fucoidan might inhibit cryptosporidiosis through the direct binding of fucoidan to the C. parvum-derived functional mediators in the intestinal epithelial cells in neonatal mice.

Animals↗
PubMed2006

Oncostatin M inhibits adipogenesis through the RAS/ERK and STAT5 signaling pathways.

Adipocytes play a key role in energy homeostasis and several cytokines have been shown to regulate adipogenesis. While the interleukin (IL)-6 family of cytokines was previously reported to be involved in adipogenesis, roles of this family in adipogenesis and their mechanisms of action are not fully understood. Here we show that among the IL-6 family, oncostatin M (OSM) most strongly inhibits adipogenesis of 3T3-L1 cells and mouse embryonic fibroblasts (MEFs). We also demonstrate that OSM inhibits adipogenesis through the Ras/extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription (STAT) 5 signaling pathways. In addition, OSM inhibits the early phase of the differentiation without affecting cell proliferation throughout adipogenesis including mitotic clonal expansion. CCAAT/enhancer-binding protein (C/EBP) alpha, C/EBPbeta, and peroxisome proliferator-activated receptor (PPAR) gamma are known to be required for adipogenesis. Expression of C/EBPalpha and PPARgamma was almost completely abrogated by OSM. In contrast, neither the mRNA nor protein level of C/EBPbeta was affected by OSM. Forced expression of C/EBPbeta induced differentiation in the presence of troglitazone, and OSM inhibited this C/EBPbeta-induced differentiation. Taken together, our results indicate that OSM inhibits the onset of terminal differentiation of adipocytes through the Ras/ERK and STAT5 signaling pathways by possibly regulating C/EBPbeta activity.

3T3-L1 Cells↗
PubMed2006

Identification and lineage tracing of two populations of somatic gonadal precursors in medaka embryos.

The gonad contains two major cell lineages, germline and somatic cells. Little is known, however, about the somatic gonadal cell lineage in vertebrates. Using fate mapping studies and ablation experiments in medaka fish (Oryzias latipes), we determined that somatic gonadal precursors arise from the most posterior part of the sdf-1a expression domain in the lateral plate mesoderm at the early segmentation stage; this region has the properties of a gonadal field. Somatic gonadal precursors in this field, which continuously express sdf-1a, move anteriorly and medially to the prospective gonadal area by convergent movement. By the stage at which these somatic gonadal precursors have become located adjacent to the embryonic body, the precursors no longer replace the surrounding lateral plate mesoderm, becoming spatially organized into two distinct populations. We further show that, prior to reaching the prospective gonadal area, these populations can be distinguished by expression of either ftz-f1 or sox9b. These results clearly indicate that different populations of gonadal precursors are present before the formation of a single gonadal primordium, shedding new light on the developmental processes of somatic gonadal cell and subsequent sex differentiation.

Animals↗
PubMed2006

Complement factor H polymorphisms in Japanese population with age-related macular degeneration.

PURPOSE: To study the frequency of five haplotypes previously reported in the complement factor H (CFH) gene for Japanese patients with age-related macular degeneration (AMD). METHODS: Genomic DNA was isolated from peripheral blood samples taken from 96 Japanese AMD patients and 89 age-matched controls. All patients were diagnosed as having exudative (wet-type) AMD. The amplified polymerase chain reaction (PCR) products of CFH exons 2, 9, and 13, and intron 6 were analyzed by temperature gradient capillary electrophoresis (TGCE) and by direct sequencing. The haplotypes were identified, and their frequencies were calculated and compared with reported results. RESULTS: Five haplotypes were identified in the Japanese population including four already reported in the American population. The frequencies of these haplotypes were significantly different between Japanese and American in both control and case groups. The haplotype containing Y402H, which was previously reported to be associated with AMD, was only 4% in the control and case population, with a p value of 0.802. However, two other haplotypes were found as risk factors, which gave an increased likelihood of AMD of 1.9 and 2.5 fold (95% CI 1.12-3.69 and 1.42-6.38). One protective haplotype that decreased the likelihood of AMD by 1.6 fold (95% CI 0.26-0.67) was identified. CONCLUSIONS: The frequencies for five haplotypes previously identified were analyzed in a Japanese population with AMD. Four previously found haplotypes were identified and one additional haplotype was found. The frequencies of each haplotype were significantly different from that in found Americans affected with AMD. Two of the haplotypes were identified as risk factors and one was considered protective.

Aged↗
PubMed2006

Time-lapse analysis reveals different modes of primordial germ cell migration in the medaka Oryzias latipes.

Previous studies have shown that medaka primordial germ cells (PGC) are first distinguishable by olvas expression during late gastrulation, and that they migrate to the gonadal region through the lateral plate mesoderm. Here, we demonstrate that medaka nanos expression marks the germ line at early gastrulation stage. By marking the germ line with green fluorescent protein (GFP) fused to the nanos 3' untranslated region, we were able to visualize the behavior of PGC using time-lapse imaging. We show that there are three distinct modes of PGC migration that function at different stages of development. At early gastrulation stage, PGC actively migrate towards the marginal zone, a process that requires the function of a chemokine receptor, CXCR4. However, at late gastrulation stage, PGC change the mode and direction of their movement, as they are carried towards the midline along with somatic cells undergoing convergent movements. After aligning bilaterally, PGC actively migrate to the posterior end of the lateral plate mesoderm. This posterior movement depends on the activity of both HMGCoAR and a ligand of CXCR4, SDF-1a. These results demonstrate that PGC undergo different modes of migration to reach the prospective gonadal region of the embryo.

Amino Acid Sequence↗
PubMed2006

Visualization of primordial germ cells in vivo using GFP-nos1 3'UTR mRNA.

In some teleost fish, primordial germ cells (PGCs) inherit specific maternal cytoplasmic factors such as vasa and nanos 1 (nos1) mRNA. It has been shown that the 3'untranslated regions (UTRs) of vasa and nos1 have critical roles for stabilization of these RNAs in zebrafish PGCs. In this study, to determine whether this role of the nos 1 3'UTR is conserved between teleost species, we injected artificially synthesized mRNA, combining green fluorescent protein (GFP) and the zebrafish nos 1 3'UTR (GFP-nos 1 3'UTR mRNA), into the fertilized eggs of various fish species. The 3'UTR of the Oryzias latipes vasa homologue (olvas ) mRNA was assayed in the same manner. We demonstrate that the PGCs of seven teleost species could be visualized using GFP-nos 1 3'UTR mRNA. GFP-olvas 3'UTR mRNA did not identify PGCs in herring or loach embryos, but did enable visualization of the PGCs in medaka embryos. Our results indicate that the 3'UTR of the zebrafish nos1 mRNA can promote maintenance of RNAs in the PGCs of different fish species. Finally, we describe and compare the migration routes of PGCs in seven teleost species.

3' Untranslated Regions↗
PubMed2006

Oncostatin m maintains the hematopoietic microenvironment and retains hematopoietic progenitors in the bone marrow.

Bone marrow (BM) functions as the primary hematopoietic tissue throughout adult life by providing a microenvironment for the proliferation, differentiation, and retention of hematopoietic stem cells and progenitors. We describe novel roles for oncostatin M (OSM) in the BM hematopoietic microenvironment. Hematopoietic progenitor activity in OSM-deficient mice was reduced in BM but elevated in the spleen and peripheral blood. The level of circulating granulocyte colony-stimulating factor (G-CSF) was increased, whereas that of stromal cell-derived factor 1 (SDF-1) was decreased in OSM-deficient mice. Moreover, the ability of OSM-deficient BM stromal cells to support hematopoiesis in vitro was significantly reduced. These results indicate that OSM plays a unique role in hematopoiesis by maintaining the proper microenvironment for BM hematopoiesis; it also retains hematopoietic progenitors in BM by regulating G-CSF and SDF-1 levels.

Animals↗
PubMed2005

Dicarboxylic degradation products of nonylphenol polyethoxylates. Determination and structural elucidation in water samples by solid-phase extraction and gas chromatography-mass spectrometry after methylation.

A reliable method combining solid-phase extraction, derivatization and gas chromatography-chemical ionization mass spectrometry (GC-CI-MS) was developed for the measurement, in river and sewage effluent water, of four select model compounds of dicarboxylic metabolites (dm-CA(5-8)P1EC) and other dicarboxylic metabolites (CA(5-8)P1ECs) of nonylphenol polyethoxylates. These selected isomers were referred as dm-CA(5-8)P1ECs because they have an alpha,alpha-dimethyl configuration (expressed as "dm"), five to eight C atoms and a carboxyl group in the alkyl chain, and an ethoxy acetic acid group. The derivatization of terminal carboxyl groups was successful with (trimethylsilyl)diazomethane. The best extraction conditions were obtained using an Oasis HLB cartridge as a sorbent bed and 4 ml of MTBE/methanol (9:1, v/v) elution mixture. The method detection limits of 0.03-0.07 microg/l for dm-CA(5-8)P1ECs were attained in 500 ml pure water. The recovery was then evaluated for pure water, river and sewage effluent water samples. The high recoveries of typically >89% for each isomer indicated the high performance of the method. Although dm-CA(5-8)P1ECs were not detected in the collected water samples, 21 isomers of CA(5-8)P1ECs were identified by CI-MS and the tentative structures of six out of them were elucidated, mainly limited to the branch at alpha-C atom, by studying the EI-mass spectra. The relative concentrations of individual CA(5-8)P1EC metabolites were calculated based on dm-CA(5-8)P1ECs. The results showed that the main degradation on the nonyl chain occurred via the elimination of two carbon-units and the concentrations in Japan were much lower than those in Taiwan and Italy.

Chemical Fractionation↗
PubMed2005

Relation between stage of endogenous fungal endophthalmitis and prognosis.

BACKGROUND: Although many studies have been published on the risk factors and therapies for endogenous fungal endophthalmitis (EFE), only a few have been published on the relationship between the stage of EFE at the initial examination and the prognosis. Thus, the purpose of this study was to determine the relation between the stage of EFE at the initial examination and the prognosis. METHODS: A total of 103 eyes of 58 patients (40 men, 18 women) with EFE, examined over a 20-year period (1984-2004), were studied. The severity of the EFE at the initial examination was classified into four stages. In addition, the type of fungus, general status, initial and final visual acuity, findings of the anterior and posterior segments, latent fungal infection, duration from initial symptoms to initial visit, history of intravenous hyperalimentation (IVH), results of the Candida Detection System, and beta-D-glucan levels were analyzed. RESULTS: More than 95% of the patients had some type of underlying disorder. Candida albicans was detected initially in the blood in 40 patients. The stage of the EFE advanced as the time from the initial symptoms to the beginning of therapy increased. The final visual acuity was significantly correlated with the stage of EFE at the initial examination. In 20 of 21 patients, blood beta-D-glucan was positive, and 42 patients (90%) were receiving IVH. CONCLUSIONS: Because the stage of EFE advanced with the time between the initial symptoms and the beginning of therapy, and because of the high correlation between the stage of EFE and the final visual acuity, it is very important that treatment be begun as soon as possible. Thus, in patients with visual symptoms and susceptible to opportunistic infections, an early consultation with an ophthalmologist is highly recommended.

Adolescent↗
PubMed2005

Selective activation of STAT5 unveils its role in stem cell self-renewal in normal and leukemic hematopoiesis.

Although the concept of a leukemic stem cell system has recently been well accepted, its nature and the underlying molecular mechanisms remain obscure. Constitutive activation of signal transducers and activators of transcription 3 (STAT3) and STAT5 is frequently detected in various hematopoietic tumors. To evaluate their role in normal and leukemic stem cells, we took advantage of constitutively active STAT mutants to activate STAT signaling selectively in hematopoietic stem cells (HSCs). Activation of STAT5 in CD34- c-Kit+ Sca-1+ lineage marker- (CD34- KSL) HSCs led to a drastic expansion of multipotential progenitors and promoted HSC self-renewal ex vivo. In sharp contrast, STAT3 was demonstrated to be dispensable for the HSC maintenance in vivo, and its activation facilitated lineage commitment of HSCs in vitro. In a mouse model of myeloproliferative disease (MPD), sustained STAT5 activation in CD34- KSL HSCs but not in CD34+ KSL multipotential progenitors induced fatal MPD, indicating that the capacity of STAT5 to promote self-renewal of hematopoietic stem cells is crucial to MPD development. Our findings collectively establish a specific role for STAT5 in self-renewal of normal as well as leukemic stem cells.

Animals↗
PubMed2005

Ion-pair solid-phase extractive derivatization of 4-alkylphenols with pentafluoropyridine for gas chromatography-mass spectrometry.

The ion-pair solid-phase extraction (SPE) of 4-alkylphenols followed by derivatization with pentafluoropyridine is demonstrated. Under alkaline conditions, the 4-alkylphenols could be efficiently adsorbed on a C18 SPE cartridge conditioned with an ion-pair reagent, tetra-n-hexylammonium bromide. The ion pairs, ammonium phenolates, formed on the C18 solid phase, were eluted with a solvent containing the derivatizing reagent, pentafluoropyridine, and completely derivatized during the elution. After optimization of the adsorption and derivatization, we established a method for the determination of the 4-alkylphenols in water samples. The method showed good linearity between 20 and 1000 ng (200-10,000 ng for nonylphenol). By processing 20-ml samples, the method detection limits (MDL) were in the range of 5.2-8.9 ng/l for the 4-alkylphenols (76 ng/l for nonylphenol). To evaluate its applicability to a real aqueous matrix, several river water samples were analyzed.

Gas Chromatography-Mass Spectrometry↗
PubMed2005

High-dose conformal radiotherapy for supratentorial malignant glioma: a historical comparison.

BACKGROUND: Although radiotherapy remains the main postoperative treatment for patients with malignant glioma, modifications to regimens have not improved the poor outlook of patients with this disease. We aimed to investigate whether high-dose conformal radiotherapy improves the survival of patients with supratentorial malignant glioma compared with conventional radiotherapy. METHODS: 29 patients with anaplastic astrocytoma and 61 patients with glioblastoma who received high-dose conformal radiotherapy during 1990-2002 were compared with 34 patients with anaplastic astrocytoma and 60 patients with glioblastoma who received conventional 60 Gy radiotherapy during 1979-89. 77 of the 90 patients receiving high-dose radiotherapy were given 80 Gy; the remaining 13 patients, all with glioblastoma, received 90 Gy. Radiotherapy was planned on the basis of images taken before surgery, and doses were delivered in 2 Gy per fraction per day for 5 days a week. Hazard ratios for death were calculated with a Cox model, and were adjusted for age, Karnofsky performance scale, tumour size, and extent of resection. FINDINGS: Patients who received high-dose radiotherapy had significantly longer overall survival compared with those who received conventional radiotherapy (adjusted hazard ratio 0.30 [95% CI 0.12-0.76], p=0.011 for anaplastic astrocytoma and 0.49 [0.28-0.87], p=0.014 for glioblastoma). Patients with anaplastic astrocytoma in the high-dose group have not yet reached median survival; median survival in the conventional radiotherapy group was 22.3 months (95% CI 20.6-24.0). 5-year survival was 51.3% (29.2-73.4) for the high-dose group and 14.7% (0.0-30.0) for the conventional group. Median survival in patients with glioblastoma was 16.2 months (12.8-19.6) for the high-dose group and 12.4 months (10.0-14.8) for the conventional group. 2-year survival was 38.4% (23.5-53.3) for the high-dose group and 11.4% (0.0-25.3) for the conventional group. Survival did not differ between those that received 80 Gy radiotherapy and those that received 90 Gy (hazard ratio 0.94 [95% CI 0.42-2.12]). The higher frequency of radiation-induced white matter abnormality in the high-dose group compared with the conventional radiotherapy group did not lead to increased disability. INTERPRETATION: High-dose, standard-fractionated radiotherapy shows potential as the main postoperative treatment for patients with supratentorial malignant glioma.

Adolescent↗
PubMed2005

Neuronal leucine-rich repeat protein 4 functions in hippocampus-dependent long-lasting memory.

Neuronal leucine-rich repeat proteins (NLRRs) are type I transmembrane proteins and expressed in neuronal tissues, but their function remains unknown. Here, we describe the identification and characterization of a new member of the NLRR family, NLRR4, and its potential role in long-lasting memory. We generated NLRR4-deficient (NLRR4(-/-)) mice and found that they showed impaired memory retention. In hippocampus-dependent learning tasks, NLRR4(-/-) mice were able to learn and maintain the memories for one day but unable to retain the memories for four days after learning. In contrast, in a hippocampus-independent task, NLRR4(-/-) mice were able to retain the memory normally for at least seven days. These results suggest that NLRR4 plays a key role in hippocampus-dependent long-lasting memory.

Amino Acid Sequence↗
PubMed2005

Safety of in vivo pharmacologic vitreolysis with recombinant microplasmin in rabbit eyes.

PURPOSE: To investigate the safety of intravitreal microplasmin in rabbits and to confirm previous findings of posterior vitreous detachment (PVD). METHODS: Different doses of microplasmin, from 12.5 microg to 250 microg, in 0.1 mL balanced salt solution (BSS) were injected into the vitreous cavity of rabbit eyes to induce PVD. Fellow eyes were injected with the same volume of BSS. Slit-lamp biomicroscopy, ophthalmoscopic fundus examinations, A- and B-mode ultrasonography, and electroretinography were performed to assess the retina. Electroretinograms (ERGs) were recorded up to 90 days after injection. Morphologic alterations were assessed by light microscopy, scanning electron microscopy (SEM), and transmission (TEM) electron microscopy. RESULTS: A slight aqueous flare and cells were observed in the anterior chamber after microplasmin and BSS injection. A slight inflammatory reaction was also observed transiently in the vitreous cavity. In control eyes, B-mode ultrasonography and SEM examination demonstrated that PVD did not develop after BSS injection. Intravitreal injections of 125 microg or greater of microplasmin induced complete PVD with an internal limiting membrane (ILM) devoid of vitreous collagen fibrils. Eyes injected with 12.5 microg microplasmin had partial PVD, and SEM showed residual fibrils covering the ILM. In all eyes, there was a transient reduction in the a- and b-waves of the ERG on days 2 through 7. The ERGs showed less effect with < 250 microg microplasmin. CONCLUSIONS: Intravitreal injection of recombinant microplasmin in the rabbit induces no ERG or retinal ultrastructural abnormalities. Pharmacologic vitreolysis with this agent may be a useful adjunct to vitreous surgery and could be used to induce PVD without vitreous surgery.

Animals↗
PubMed2005

Quantitative bio-imaging analysis for evaluation of sexual differentiation in germ cells of olvas-GFP/ST-II YI medaka (Oryzias latipes) nanoinjected in ovo with ethinylestradiol.

We examined the effects on sexual differentiation of nanoinjecting ethinylestradiol (EE2) into embryos of olvas-GFP/ST-II YI medaka (Oryzias latipes). This strain contains the green fluorescent protein (GFP) gene fused to the regulatory region of the medaka vasa gene, and germ-cell-specific expression of GFP can be visualized in living (transparent) individuals. The number of germ cells in untreated genotypic females (XX) was approximately 10-fold that in untreated genotypic males (XY) at 10 d posthatch (dph). Germ cell proliferation was prevented in XX females that developed from embryos nanoinjected with 0.5, 2.5, or 5.0 ng of EE2. Some 10-dph XY males from embryos injected with 0.5 ng or more of EE2 showed a larger fluorescent area and more germ cells than those of pooled control groups. Males and females from embryos injected with 5.0 ng of EE2 had no significant difference in germ cell number or fluorescent area. Thus, EE2 injection into embryos caused abnormal gonadal development in both sexes. Observations of external secondary sex characteristics and histological examination of adult gonads showed complete sex reversal in some males after 0.5-, 2.5-, and 5.0-ng treatments but no changes in XX females after any treatment. Thus, quantitative bio-imaging can aid in evaluating the effects of endocrine-disrupting chemicals on fish within 10 dph.

Animals↗
PubMed2004

Dicarboxylic degradation products of nonylphenol polyethoxylates: synthesis and identification by gas chromatography-mass spectrometry using electron and chemical ionization modes.

The synthesis, mass spectra and detectability of four selected dicarboxylic degradation products (CAPECs) of nonylphenol polyethoxylates (NPEOs) are reported. The selected isomers have an alpha,alpha-dimethyl configuration (expressed as "dm" in their abbreviation), five to eight C atoms and a carboxyl group in the alkyl chain, and a carboxymethoxy acid group (dm-CA5-8P1ECs). The synthesis was successfully accomplished via a reaction sequence that started from anisole. After trimethylsilylation with N,O-bis(trimethylsilyl)acetamide or methylation with (trimethylsilyl)diazomethane, the derivatives of the dm-CA5-8P1ECs were subjected to a GC-electron ionization (EI)-MS and GC-isobutane chemical ionization (CI)-MS. In EI-MS, ion peaks at m/z = 265 and 207, corresponding to the alpha,alpha-dimethyl structures via the benzyl cleavage of carboxyalkyl chain, were the most significant ions of the trimethylsilyl and methyl derivatives, respectively. In CI-MS, the main ion peaks of dm-CA5-, dm-CA6-, dm-CA7-, and dm-CA8P1EC after methylation were at m/z= 129, 143, 157, and 171, respectively, corresponding to the loss of methyl phenoxyacetate from [M+ H]+; meanwhile significant peaks were detected at 321, 335, 349, and 363, corresponding to the loss of the trimethylsilanol after trimethylsilylation. The potential for the identification and quantification of individual branched carboxyalkyl isomeric mixtures of CA5-, CA6-, CA7-, and CA8P1EC metabolites based on corresponding dm-CA5-8P1ECs revealed the advantage of the GC-CI-MS although the detection limits in CI were clearly higher than those in EI.

Dicarboxylic Acids↗