Biomedical subjects

Yoshiaki Takahashi

Publications and source records attributed to Yoshiaki Takahashi.

15 recordsLinked to original sources

PubMed2006

Human T-cell leukemia virus type-I Tax induces expression of interleukin-6 receptor (IL-6R): Shedding of soluble IL-6R and activation of STAT3 signaling.

Human T-cell leukemia virus type-I (HTLV-I) encodes for the viral protein Tax, which is known to significantly disrupt transcriptional control of cytokines, cytokine receptors and other immuno-modulatory proteins in T cells. Specific dysregulation of these factors can alter the course and pathogenesis of infection. Soluble interleukin-6 receptor (sIL-6R) was shown to circulate at elevated levels in HTLV-I-infected patients, and high expressions of IL-6R and sIL-6R by HTLV-I-infected T cells were clinically and experimentally associated with Tax activity. To examine roles of Tax in expression of the IL-6R gene, the JPX-9 cell line was used, which is derived from Jurkat cell line expressing Tax cDNA. Over-expression of Tax enhanced IL-6R expression but not in Tax mutant JPX-9/M cell line. The clinical relevance of these observations was further demonstrated by ELISA using sera obtained from HTLV-I-infected patients. Our results revealed that sIL-6R levels were apparently elevated in HAM/TSP patients who were expressing Tax in their cells, while ATL patients' cells barely expressed Tax. HTLV-I-infected T-cell lines stimulated by IL-6/sIL-6R showed gp130-mediated STAT3 activity. IL-6/sIL-6R enhanced proliferation of HTLV-I-infected T cells in association with activation of STAT3. Consequently, Tax-mediated regulations of IL-6R and sIL-6R observed in HTLV-I-associated disorders may contribute to proliferation of HTLV-I-infected T cells through activation of inducible STAT3, and ultimately affect malignant growth and transformation of T cells by HTLV-I.

Cell Line↗

PubMed2006

Reduced expression of p63 has prognostic implications for patients with esophageal squamous cell carcinoma.

The p63 gene is a member of the p53 family that plays a role in cell differentiation, development and carcinogenesis. The relationship between p63 expression and the prognosis of esophageal squamous cell carcinoma (ESCC) remains unknown. The present study examines the clinical impact of p63 in patients with ESCC. Resected specimens from 180 patients with ESCC were immunostained for p63 and p53. After establishing a cut-off value for p63 expression, we statistically examined its clinical impact and relationship to p53 expression. At a 50% cut-off value for p63 expression, the 5-year overall survival was significantly longer in p63-positive (46.4%) than -negative patients (11.1%, p=0.05). Among the 180 ESCC patients, 171 (95.0%) were p63 immunoreactive and only 9 (5.0%) were negative. The correlation between p63 status and clinicopathological parameters was not significant, although p63-negativity tended to correlate with distant metastasis (p=0.06) and clinical stage (p=0.08). Univariate analysis demonstrated significant correlations between patient survival and tumor diameter, depth of invasion, lymphatic invasion, vascular invasion, lymph node metastasis and distant metastasis. The survival of patients who did not express p63 and p53 was obviously unfavorable (p=0.03). Multivariate analysis revealed that only lymph node metastasis was a critical independent prognostic marker for overall survival (p=0.0015). Expression of p63 was not an independent prognostic factor for overall survival in this study (p=0.69). These data suggest that, although a reduced expression of p63 is infrequent, it has a prognostic impact upon patients with ESCC.

Aged↗

PubMed2005

Development of molecular probes for dinophysis (dinophyceae) plastid: a tool to predict blooming and explore plastid origin.

Dinophysis are species of dinoflagellates that cause diarrhetic shellfish poisoning. We have previously reported that they probably acquire plastids from cryptophytes in the environment, after which they bloom. Thus monitoring the intracellular plastid density in Dinophysis and the source cryptophytes occurring in the field should allow prediction of Dinophysis blooming. In this study the nucleotide sequences of the plastid-encoded small subunit ribosomal RNA gene and rbcL (encoding the large subunit of RuBisCO) from Dinophysis spp. were compared with those of cryptophytes, and genetic probes specific for the Dinophysis plastid were designed. Fluorescent in situ hybridization (FISH) showed that the probes bound specifically to Dinophysis plastids. Also, FISH on collected nanoplankton showed the presence of probe-hybridized eukaryotes, possibly cryptophytes with plastids identical to those of Dinophysis. These probes are useful not only as markers for plastid density and activity of Dinophysis, but also as tools for monitoring cryptophytes that may be sources of Dinophysis plastids.

Animals↗

PubMed2005

Caprazamycins, novel lipo-nucleoside antibiotics, from Streptomyces sp. II. Structure elucidation of caprazamycins.

Novel antibiotics, active against acid-fast bacteria, caprazamycins, were isolated from the culture broth of Streptomyces sp. MK730-62F2. The planar structures of the compounds were determined by 2D NMR spectroscopic study. Furthermore, the absolute structure of caprazamycin B (2) was established by NMR spectroscopy and X-ray crystallography of its degradation products and by total synthesis of the 5-amino-5-deoxy-D-ribose moiety. In the course of degradation studies of 2 under alkaline and acidic conditions, we obtained the two core components, caprazene (11) and caprazol (14), respectively, in high yield. Structurally, caprazamycins belong to a family of lipouridyl antibiotics, which have been discovered as specific inhibitors of a bacterial translocase.

Animals↗

PubMed2005

Ribosomal proteins cross-linked to the initiator AUG codon of a mRNA in the translation initiation complex by UV-irradiation.

Eukaryotic ribosomal proteins constituting the binding site for the initiator codon AUG on the ribosome at the translation initiation step were investigated by UV-induced cross-linking between protein and mRNA. The 80S-initiation complex was formed in a rabbit reticulocyte cell-free system in the presence of sparsomycin with radiolabeled Omega-fragment as a template, which was a 73-base 5'-leader sequence of tobacco mosaic virus RNA having AUG at the extreme 3'-terminal end and extended with 32pCp. Two radioactive peaks were sedimented by sucrose gradient centrifugation, one being the 80S initiation complex formed at the 3'-terminal AUG codon, and the other presumably a "disome" with an additional 80S ribosome bound at an upstream AUU codon, formed when Omega-fragment was incubated with sparsomycin [Filipowicz and Henni (1979) Proc. Natl. Acad. Sci. USA 76, 3111-3115]. Cross-links between ribosomal proteins and the radiolabeled Omega-fragment were induced in situ by UV-irradiation at 254 nm. After extensive nuclease digestion of the complexes, ribosomal proteins were separated by two-dimensional gel electrophoresis. Autoradiography identified the proteins S7, S10, S25, S29, and L5 of the 80S initiation complex and S7, S25, S29 and L5 of that in the disome as 32P-labeled proteins. Together with the results of cross-linking experiments of other investigators and recently solved crystal structures of prokaryotic ribosomes, the spatial arrangement of eukaryotic ribosomal proteins at the AUG-binding domain is discussed.

Animals↗

PubMed2005

Impact of nuclear galectin-3 expression on histological differentiation and vascular invasion in patients with esophageal squamous cell carcinoma.

Expression of galectin-3, a member of the beta-galactosidase binding lectin family, is reported to correlate with cell adhesion. The present immunohistochemical study was performed to clarify the impact of galectin-3 expression on patients with esophageal squamous cell carcinoma. Galectin-3 expression was examined immunohistochemically in 154 patients with esophageal squamous carcinoma, who had undergone surgery without preoperative supplemental therapy at the Department of Surgery II in the Hospital of the Faculty of Medicine, Oita University, between 1990 and 2000. The cases with > or =30% nuclear-stained cancer cells were considered high nuclear expression cases. In contrast, the cases with > or =45% cytoplasm-stained cancer cells were considered high cytoplasm expression cases. Twenty-three of 154 ESCC cases were regarded as high nuclear expression (14.9%) and 72 of 154 cases were regarded as high cytoplasm-expression (46.5%). High expression of galectin-3 in the nuclei inversely correlated with vascular invasion (p=0.030) and histological differentiation (p=0.0064). In contrast, cytoplasmic expression of galectin-3 revealed no significant impact on clinicopathological factors. Neither nuclear nor cytoplasmic expression of galectin-3 was a prognostic indicator in ESCC. Elevated expression of galectin-3 in the nuclei but not the cytoplasm may be an important biological parameter related to histological differentiation and vascular invasion in patients with ESCC.

Adult↗

PubMed2004

Anomalous decrease in lamellar spacing by shear flow in a nonionic surfactant/water system.

We study the effects of shear flow on the structure of a lamellar phase in a C16E7 [hepta(oxyethylene glycol)-n-hexadecyl ether]/water system (40-55 wt % of C16E7) at 70 degrees C using small-angle neutron scattering in the range of shear rate of 10(-3)-30 s(-1). At the shear rate 0.1-1 s(-1), the repeat distance (d) is decreased significantly (down to about 40% of d at rest in the most significant case) and discontinuously with increasing shear rate. With the further increase in the shear rate, d increases through a sharp minimum (referred to as d*). Such a shear rate dependence of d is obtained for all the principal orientations of lamellae. As the concentration of C16E7 decreases from 55 to 40 wt %, d increases from 6.5 to 8.5 nm at rest whereas d* remains almost constant (approximately equal to 5 nm). Moreover, d* is found to be almost equal to the thickness of bilayers obtained from the line shape analysis of small-angle X-ray scattering at rest. The results strongly suggest that the water layer is excluded by shear flow and that the lamellar phase segregates into surfactant-rich and water-rich regions, although these regions do not reach macroscopic size.

Letter↗

PubMed2004

Regrowth of lymphatic vessels following transection of the muscle coat in the rat small intestine.

Regeneration of lymphatic vessels after transection of the muscle coat in the rat jejunum was studied by histochemical methods. The lymphatic regrowth occurred behind the regeneration of blood vessels. Enzyme histochemistry for 5'-nucleotidase (5'-Nase) demonstrated the manner of lymphatic regrowth, which was essentially attributed to vascular sprouting from preexisting lymphatics, and structural changes of the endothelial cells indicating their high migratory potential. The lymphatic regeneration progressively advanced with vascular maturation throughout the experimental period. The expression of 5'-Nase in the regenerating lymphatics was increased in proportion to their growth. VEGF-C, a highly specific lymphangiogenic factor, was highly expressed in a subpopulation of interstitial cells, being close to the regrowing lymphatics with immunoreactivity of its receptor, VEGFR-3, in the regenerative area. The present findings suggest that transection of the intestinal muscle coat affords a useful experimental model for the investigation of lymphatic regeneration in tissue repair and that the interstitium may play a crucial role in lymphangiogenesis.

5'-Nucleotidase↗

PubMed2003

Homozygous deletions and point mutations of the Rit1/Bcl11b gene in gamma-ray induced mouse thymic lymphomas.

Allelic loss (LOH) mapping and sequence analysis were conducted for gamma-ray induced mouse thymic lymphomas and a novel tumor suppressor gene, Rit1/Bcl11b, on chromosome 12 was isolated. Bi-allelic changes were found in 17 of the 66 p53-proficient lymphomas with Rit1 LOH but in only 2 of the 54 p53-deficient lymphomas. This suggests an association between the presence of functional p53 and inactivation of the Rit1 gene in the lymphoma development. Introduction of Rit1 into HeLa cells lacking Rit1 expression suppressed cell growth. These results indicate that loss-of-function mutations of Rit1 contribute to mouse lymphomagenesis and possibly to human cancer development.

Alleles↗

PubMed2003

Induction of protective immune responses against R5 human immunodeficiency virus type 1 (HIV-1) infection in hu-PBL-SCID mice by intrasplenic immunization with HIV-1-pulsed dendritic cells: possible involvement of a novel factor of human CD4(+) T-cell origin.

The potential of a dendritic cell (DC)-based vaccine against human immunodeficiency virus type 1 (HIV-1) infection in humans was explored with SCID mice reconstituted with human peripheral blood mononuclear cells (PBMC). HIV-1-negative normal human PBMC were transplanted directly into the spleens of SCID mice (hu-PBL-SCID-spl mice) together with autologous mature DCs pulsed with either inactivated HIV-1 (strain R5 or X4) or ovalbumin (OVA), followed by a booster injection 5 days later with autologous DCs pulsed with the same respective antigens. Five days later, these mice were challenged intraperitoneally with R5 HIV-1(JR-CSF). Analysis of infection at 7 days postinfection showed that the DC-HIV-1-immunized hu-PBL-SCID-spl mice, irrespective of the HIV-1 isolate used for immunization, were protected against HIV-1 infection. In contrast, none of the DC-OVA-immunized mice were protected. Sera from the DC-HIV-1- but not the DC-OVA-immunized mice inhibited the in vitro infection of activated PBMC and macrophages with R5, but not X4, HIV-1. Upon restimulation with HIV-1 in vitro, the human CD4(+) T cells derived from the DC-HIV-1-immunized mice produced a similar R5 HIV-1 suppressor factor. Neutralizing antibodies against human RANTES, MIP-1alpha, MIP-1beta, alpha interferon (IFN-alpha), IFN-beta, IFN-gamma, interleukin-4 (IL-4), IL-10, IL-13, IL-16, MCP-1, MCP-3, tumor necrosis factor alpha (TNF-alpha), or TNF-beta failed to reverse the HIV-1-suppressive activity. These results show that inactivated HIV-1-pulsed autologous DCs can stimulate splenic resident human CD4(+) T cells in hu-PBL-SCID-spl mice to produce a yet-to-be-defined, novel soluble factor(s) with protective properties against R5 HIV-1 infection.

AIDS Vaccines↗

PubMed2003

Ribonuclease inhibitors in Malus x domestica (common apple): isolation and partial characterization.

A ribonuclease inhibitory activity was detected in the fruits of common apple, Malus x domestica, cv. Fuji, and purified by affinity chromatography on ribonuclease A-Sepharose. It inhibited hydrolysis of cyclic-2':3'-CMP by bovine pancreatic ribonuclease A with an apparent inhibition constant of about 5 x 10(-8) M. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of the purified protein gave two peaks corresponding to the mass numbers of 55,658 and 62,839, while three bands of 43-, 34-, and 21-kDa were detected by SDS-PAGE. These results suggested that the inhibitor preparation was a mixture of two proteins comprised of 43- and 21-kDa subunits or of 34- and 21-kDa subunits. Attempts to separate these two proteins were unsuccessful. Amino acid composition and N-terminal amino acid sequence of these subunits were also identified and N-terminal sequences showed some similarity to that of cottonseed storage globulin. The significance of the presence of ribonuclease inhibitors in apple fruits is not clear, but it might allow some speculation about their possible involvement in the control of the self-incompatibility ribonuclease of Rosaceae plants.

Amino Acid Sequence↗

PubMed2003

[An autopsy case of multiple system atrophy with a heteroallelic ceruloplasmin gene mutation].

We reported a 69-year-old woman with multiple system atrophy (MSA), who had a heteroallelic missense mutation (G1874A, Gly-->Glu) in the exon 11 of the ceruloplasmin (Cp) gene. At the age of 64, she began to complain of progressive gait disturbance, which was resistant to anti-Parkinsonian drug treatment. Neurological examination revealed parkinsonism such as rigidity, akinesia, mild tremor and postural instability, accompanying saccadic eye movement, dysarthria, dysphagia, orthostatic hypotension and bladder disturbance. She showed neither cerebellar signs nor dementia. Serum Cp and copper concentrations were 13-18 mg/dl and 38-56 micrograms/dl, respectively, which were decreased to about a half of normal values. Brain MRIs revealed high intensity areas in the bilateral putamens in the T2-weighted image, and mild pontine base atrophy. She died of respiratory failure due to laryngeal paresis after five years from the onset. Neuropathological examination revealed brown-colored putamens, where there was severe neuronal cell loss with gliosis. Though atrophy of the pontine base was mild, transverse myelinated fibers were pale in Klüver-Barrera stain. There were Purkinje cell loss of moderate degree and appearance of torpedos in the cerebellum. Both silver staining and immunohistochemical staining to alpha-synuclein showed glial cytoplasmic inclusions, which were found predominantly in the putamens. These clinical features and neuropathological findings were compatible with multiple system atrophy (MSA). Iron staining of the brain revealed iron deposition in the putamens and the substantia nigra, but not in the pontine base nor in the cerebellum. Furthermore, we failed to reveal it in both the liver and the pancreas as well as the thalamus and the caudate nucleus, which were common sites of iron deposition in the previous cases of Cp gene mutation. We have already reported three other MSA cases with a- or hypo-ceruloplasminemia with similar clinical and pathological features to this case. One of them, in which gene analysis was also available, did not have any mutations in its Cp gene. Therefore, the gene mutation of this case may not be a direct cause to MSA, but the fact that the most cases of MSA with hypoceruloplasminemia showed striatonigral degeneration (SND) type implies some relationship between hypoceruloplasminemia and SND.

Aged↗

PubMed2002

A patient with primary gastric choriocarcinoma who received a correct preoperative diagnosis and achieved prolonged survival.

Primary choriocarcinoma of the stomach is an extremely rare and highly malignant tumor. A 68-year-old Japanese man was admitted to our department with symptoms of epigastric pain, abdominal fullness, and dizziness. Primary gastric choriocarcinoma with regional lymph node metastases was diagnosed preoperatively by the detection of elevated serum levels of a tumor marker, radiography, and immunohistochemical staining of biopsy specimens. The patient underwent total gastrectomy and jejunal reconstruction (Roux-en-Y method), followed by chemotherapy. Histological examination of the resected stomach revealed typical choriocarcinoma accompanied by common adenocarcinomatous elements. After postoperative chemotherapy the patient survived for 4 years and 6 months, and died with no evidence of recurrence of carcinoma. This is the first known patient with primary gastric choriocarcinoma to have survived for such a long period without recurrent elevation of the serum level of human chorionic gonadotropin (HCG), which was a useful marker when reevaluating the patient.

Adult↗

PubMed2002

Scanning electron microscopic observation of immunohistochemically specified stromal cells following the NaOH maceration method.

The present study introduces a method combining immunohistochemistry and a chemical digestion technique applied to scanning electron microscopy (SEM) observation of chemically characterized stromal cells in the myenteric layer of the monkey small intestine. The whole-mount preparation containing the myenteric layer was treated immunohistochemically using small colloidal gold and silver enhancements for detecting a certain type of stromal cell, followed by an alkali maceration method to remove extracellular matrices covering the immunohistochemically stained cells. This method permitted direct SEM observation of the stained stromal cells. Secondary and backscatter electron images clearly visualized the ultrastructure of the immunohistochemically-stained cells and the spatial distribution of the reaction products, respectively. It is suggested that the present method is useful for demonstrating the three-dimensional organization of the chemically specified stromal cells.

Animals↗

PubMed2002

Identification of the ribosomal proteins present in the vicinity of globin mRNA in the 40S initiation complex.

The interaction of ribosomal proteins with mRNA in the 40S initiation complex was examined by chemical cross-linking. 40S initiation complexes were formed by incubating rat liver [(3)H]Met-tRNAi, rat liver 40S ribosomal subunits, rabbit globin mRNA, and partially purified initiation factors of rabbit reticulocytes in the presence of guanylyl(beta, gamma-methylene)-diphosphonate. The initiation complexes were then treated with 1,3-butadiene diepoxide to introduce crosslinks between the mRNA and proteins. The covalent mRNA-protein conjugates were isolated by chromatography on an oligo(dT) cellulose column in the presence of sodium dodecyl sulfate, followed by sucrose density gradient centrifugation. Proteins cross-linked to the mRNA were labeled with Na(125)I, extracted by extensive ribonuclease digestion, and analyzed by two-dimensional and diagonal polyacrylamide gel electrophoresis. Three ribosomal proteins, S6, S8, and S23/S24, together with small amounts of S3/S3a, S27, and S30, were identified as the protein components cross-linked to the globin mRNA protein complex, and were shown to attach directly to the mRNA. It is suggested that these proteins constitute the ribosomal binding site for mRNA in the 40S initiation complex.

Animals↗