Biomedical subjects

T Otsuka

Publications and source records attributed to T Otsuka.

At least 73 records · Page 4Linked to original sources

PubMed2000

Synovial inflammation and hyperplasia induced by gliostatin/platelet-derived endothelial cell growth factor in rabbit knees.

Neovascularization, proliferation of synovial cells, and mononuclear cell influx and activation are characteristic events observed in synovial joints in the pathohistology of rheumatoid arthritis (RA). The objective of this study was to examine synovial inflammation in rabbit knees induced by intra-articular administration of human gliostatin/platelet-derived endothelial cell growth factor (GLS/PD-ECGF), which shares a high degree of chemical homology with thymidine phosphorylase (dThdPase) and is known to have angiogenic activity. Purified recombinant human gliostatin (rHuGLS) and its mutant protein, which was prepared by site-directed mutagenesis and which lacks dThdPase activity, were administered at various doses to rabbit knee joints. The effects of rHuGLS and the mutant were examined histologically. Intra-articular injection of rHuGLS resulted in the development of diffuse synovitis resembling RA. The mutant protein also brought about the same effect. These findings suggest that human GLS can cause RA-like synovitis in rabbit knee joints via a mechanism other than its dThdPase activity.

Animals↗

PubMed2000

Constituents of Boronia pinnata.

A novel quinolone, pinolinone (1); seven new phenylpropanoids, boropinols A (2), B (3), C (4), boropinals A (5), B (6), C (7), and boropinic acid (8); and a new lignan, boropinan (9), were isolated from the roots of Boronia pinnata, and their structures were elucidated by NMR and MS analyses. In a search for novel cancer chemopreventive agents (antitumor-promoters), we screened 10 compounds isolated from the plant for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate in Raji cells. Boropinic acid (8) and 4'-hydroxy-3'-prenylcinnamaldehyde were observed to significantly inhibit the EBV-EA activation.

Alkaloids↗

PubMed2000

Association of SYT-SSX fusion types with proliferative activity and prognosis in synovial sarcoma.

The t(X;18)(p11.2;q11.2) translocation commonly found in synovial sarcoma (SS) results in the fusion of the SYT gene on chromosome 18 to either of two closely related genes, SSX1 and SSX2, on chromosome X. It has been suggested that patients who have SS bearing SYT-SSX1 fusion have worse prognosis than those bearing SYT-SSX2 fusion. However, little is known about the biologic basis or the relationship with the histopathologic risk factors in regard to the different fusion types. We analyzed 19 cases of SS with no metastasis at diagnosis. These tumors were classified by reverse transcription-polymerase chain reaction to SYT-SSX1 and SYT-SSX2 types. The expression of Ki-67, p27, p53, and bcl-2 and various clinicopathologic parameters including mitotic rate were compared between the two fusion types. The SYT-SSX1 type fusion was associated with high Ki-67 expression (P = .011) and high mitotic rate (P = .070). No significant differences were found between the two types as to the expression of p27, p53, and bcl-2 and other clinicopathologic parameters. The survival analysis showed that SYT-SSX1-type fusion, high Ki-67 expression, and high mitotic rate correlated with shorter metastasis-free survival. These data suggested that SYT-SSX fusion type is associated with tumor cell proliferative activity and prognosis of patients who have SS.

Adolescent↗

PubMed2000

Proliferative involvement of ENX-1, a putative human polycomb group gene, in haematopoietic cells.

Homeobox genes have important roles in haematopoiesis and are regulated in an activated state by the trithorax group (trxG) of genes. In a repressed state, they are regulated by the Polycomb group (PcG) of genes. ENX-1, a putative human PcG gene product, interacts with the proto-oncogene product Vav. We report an investigation of the role of ENX-1 in human haematopoiesis. CD34+ cells mobilized to peripheral blood strongly expressed ENX-1. When stimulated to proliferate, both T and B lymphocytes rapidly up-regulated ENX-1. ENX-1 was expressed in all cell lines of the various lineages examined. When HL-60 cells were differentiated to mature granulocytes with all-trans retinoic acid, ENX-1 was down-regulated. Moreover, ENX-1 antisense oligodeoxynucleotide suppressed DNA synthesis in HL-60 cells. Our data indicate that ENX-1 is involved in the proliferation of both normal and malignant haematopoietic cells.

Antineoplastic Agents↗

PubMed2000

Human thymic epithelial cells maintain long-term survival of clonogenic myeloid and erythroid progenitor cells in vitro.

Precursor cells that migrate into the thymus are still multipotent. Therefore, thymic epithelial cells (TECs) may provide microenvironments not only for T-cell development, but also for maintenance of multipotent precursor cells until they undergo T-cell commitment. In the present study, we performed long-term cultures of CD34+ bone-marrow (BM) cells on TEC lines that were derived from cortical epithelial cells of post-natal thymus, to investigate whether human TECs could maintain long-term nonlymphoid haematopoiesis. Haematopoietic cells maintained in direct contact with established TEC lines were able to generate clonogenic progeny to both myeloid and erythroid cells for periods in excess of 5 weeks. Their abilities to support colony-forming units of granulocytes-macrophages (CFU-GM) and burst-forming units of erythroids (BFU-E) were almost equal to those of BM stromal cells. We observed similar results by using cloned TEC lines derived by limiting dilution, as well as those by using parental TEC lines. Colony-forming activities were maintained even when haematopoietic progenitor cells were physically separated from TEC lines and cultured on microporous membrane. These observations indicate that haematopoiesis maintained in TEC-contact long-term cultures may depend on soluble factors produced by TEC lines. Our results suggest that thymic cortical epithelial cells have the ability to support not only the differentiation of haematopoietic cells, but also long-term survival of clonogenic myeloid/erythroid progenitor cells.

Antigens, CD34↗

PubMed2000

Induction of MTG8-specific cytotoxic T-cell lines: MTG8 is probably a tumour antigen that is recognized by cytotoxic T cells in AML1-MTG8-fused gene-positive acute myelogenous leukaemia.

Several reports have demonstrated the persistent detection of AML1-MTG8 fusion products, representing minimal residual disease (MRD), in patients with t(8;21) acute myelogenous leukaemia (AML) who are in long-term remission. It is probable that immune-mediated mechanisms that are able to suppress the expansion of MRD may result in the continuance of remission. It was previously shown that some t(8;21) AML patients had high anti-MTG8 antibody titres. MTG8 expression in normal adult tissues is limited to the brain or heart in which human leucocyte antigen (HLA) class I cell-surface antigens are either not or are only faintly detectable. We hypothesized that the overexpression of the MTG8 gene in t(8;21) AML cells could act as a possible tumour antigen, which might be able to induce the immune-mediated suppression of the expansion of MRD. We were able to induce HLA-A0201-restricted cytotoxic T-lymphocyte (CTL) lines against an MTG8 peptide (MTG8b amino acids 182-191) using monocyte-derived dendritic cells from a healthy donor. T-cell receptor (TCR)Valpha17, TCRVbeta14 and 15, and TCRJbeta2.1 and 2.3 are predominantly used in these CTL lines. Our data, which suggest that the MTG8 protein could be one of the tumour antigens recognized by CTLs, may be helpful in further investigations of TCR analysis in t(8;21) AML patients with HLA-A0201 who are in long-term remission.

Antigens, Neoplasm↗

PubMed2000

Ribonuclease H attack of leukaemic fused transcripts AML1-MTG8 (ETO) by DNA/RNA chimeric hammerhead ribozymes.

BACKGROUND: Catalytic anti-sense oligonucleotides might be useful tools for controlling specific gene expression. However, to obtain effective oligonucleotides of the desired function in vivo is still a difficult task. RESULTS: To evaluate the usefulness of synthesized DNA/RNA hammerhead ribozymes targeting AML1-MTG8 (ETO) leukaemic fusion transcripts in vivo, we analysed their effects on cell growth and the mechanism of action using isolated cell nuclei. These ribozymes inhibited the growth of leukaemic cell lines expressing the AML1 -MTG8 and degraded AML1-MTG8 mRNA in isolated nuclei of these cells. However, the reactions gave rise to additional cleavage products. Systematic cleavage analyses using an anti-sense oligonucleotide array revealed that the cleavage was induced by endogenous RNase H at specific sites, in accordance with their calculated melting temperature (Tm) values. With suppression of RNase H by sulfhydryl agents, the DNA/RNA ribozyme had a ribozyme catalytic activity. In addition, the ribozymes and anti-sense oligonucleotides suppressed the AML1-MTG8 protein in the leukaemic cells. CONCLUSIONS: The DNA/RNA ribozymes inhibited cell growth primarily via anti-sense effects, the main role of which was the activation of RNase H-digestion by their DNA arms. In addition, the isolated nuclei provided a useful assay system for modelling in vivo conditions for the quantitative evaluation of anti-sense/ribozyme activity.

Antisense Elements (Genetics)↗

PubMed2000

Pharmacokinetics of a parenteral carbapenem, biapenem, in patients with end-stage renal disease and influence of haemodialysis.

The effects of haemodialysis on the pharmacokinetics of a carbapenem, biapenem, were evaluated in five patients with end-stage renal disease, who received 1 h iv infusions of 300 mg biapenem on both the days on and off 4 h haemodialysis. With haemodialysis, plasma biapenem exhibited two elimination phases, one during and the other after haemodialysis with half-lives of 1.16 +/- 0.12 and 3.33 +/- 0. 91 h, respectively. Ninety percent of biapenem was removed from blood to dialysate. Without haemodialysis, plasma biapenem was mono-exponentially eliminated with a half-life of 4.35 +/- 1.30 h.

Adult↗

PubMed2000

The role of telomerase activity in hepatocellular carcinoma.

OBJECTIVE: The aim of this study was to clarify the role of telomerase activity in hepatocellular carcinoma (HCC). METHODS: Specimens from both HCC and noncancerous liver were obtained from 39 patients with HCC using a 14-gauge biopsy needle immediately after laparotomy. Telomerase activity was determined using a telomeric repeat amplification protocol assay. The 3+ of telomerase activity in HCC was defined as a high telomerase group, and 2+ or less of HCC telomerase activity was defined as a low telomerase group. In noncancerous liver, 2+ or more of telomerase activity was defined as an increased telomerase group, and 1+ or less of telomerase activity was defined as a nonincreased telomerase group. The correlation between telomerase activity in HCC or noncancerous liver and clinicopathological factors, including prognosis, was investigated. RESULTS: Telomerase activities in HCCs were 0 in one patient, 1+ in two, 2+ in seven, and 3+ in 29 patients. The disease-free survival rate in the high telomerase group was significantly worse than that in the low telomerase group. The des-gamma-carboxy prothrombin level in a high telomerase group (median, 330 mAU/ml) was significantly higher than that in the low telomerase group (median, 150 mAU/ml). A multivariate analysis revealed that higher TNM stage, high telomerase activity in HCC, female gender, and high alpha-fetoprotein value were independent significant factors related to be early recurrence. The incidence of multicentric HCC occurrence in the increased telomerase group (53.3%) tended to be higher than that in the nonincreased telomerase group (27.3%). CONCLUSION: A high telomerase activity in HCC correlated with the potential of HCC to be more malignant, which was expressed as both a high level of des-gamma-carboxy prothrombin and an earlier recurrence after hepatectomy than that of HCC with a low telomerase activity.

Adult↗

PubMed2000

Disassociation of met-mediated biological responses in vivo: the natural hepatocyte growth factor/scatter factor splice variant NK2 antagonizes growth but facilitates metastasis.

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates numerous cellular activities capable of contributing to the metastatic phenotype, including growth, motility, invasiveness, and morphogenetic transformation. When inappropriately expressed in vivo, an HGF/SF transgene induces numerous hyperplastic and neoplastic lesions. NK1 and NK2 are natural splice variants of HGF/SF; all interact with a common receptor, Met. Although both agonistic and antagonistic properties have been ascribed to each isoform in vitro, NK1 retains the full spectrum of HGF/SF-like activities when expressed as a transgene in vivo. Here we report that transgenic mice broadly expressing NK2 exhibit none of the phenotypes characteristic of HGF/SF or NK1 transgenic mice. Instead, when coexpressed in NK2-HGF/SF bitransgenic mice, NK2 antagonizes the pathological consequences of HGF/SF and discourages the subcutaneous growth of transplanted Met-containing melanoma cells. Remarkably, the metastatic efficiency of these same melanoma cells is dramatically enhanced in NK2 transgenic host mice relative to wild-type recipients, rivaling levels achieved in HGF/SF and NK1 transgenic hosts. Considered in conjunction with reports that in vitro NK2 induces scatter, but not other activities, these data strongly suggest that cellular motility is a critical determinant of metastasis. Moreover, our results demonstrate how alternatively structured ligands can be exploited in vivo to functionally dissociate Met-mediated activities and their downstream pathways.

Animals↗

PubMed2000

Characterization of Ca(2+) channels in rat subthalamic nucleus neurons.

The subthalamic nucleus (STN) plays a key role in motor control. Although previous studies have suggested that Ca(2+) conductances may be involved in regulating the activity of STN neurons, Ca(2+) channels in this region have not yet been characterized. We have therefore investigated the subtypes and functional characteristics of Ca(2+) conductances in STN neurons, in both acutely isolated and slice preparations. Acutely isolated STN cells were identified by retrograde filling with the fluorescent dye, Fluoro-Gold. In acutely isolated STN neurons, Cd(2+)-sensitive, depolarization-activated Ba(2+) currents were observed in all cells studied. The current-voltage relationship and current kinetics were characteristic of high-voltage-activated Ca(2+) channels. The steady-state voltage-dependent activation curves and inactivation curves could both be fitted with a single Boltzmann function. Currents evoked with a prolonged pulse, however, inactivated with multiple time constants, suggesting either the presence of more than one Ca(2+) channel subtype or multiple inactivation processes with a single channel type in STN neurons. Experiments using organic Ca(2+) channel blockers revealed that on average, 21% of the current was nifedipine sensitive, 52% was sensitive to omega-conotoxin GVIA, 16% was blocked by a high concentration of omega-agatoxin IVA (200 nM), and the remainder of the current (9%) was resistant to the co-application of all blockers. These currents had similar voltage dependencies, but the nifedipine-sensitive current and the resistant current activated at slightly lower voltages. omega-Agatoxin IVA at 20 nM was ineffective in blocking the current. Together, the above results suggest that acutely isolated STN neurons have all subtypes of high-voltage-activated Ca(2+) channels except for P-type, but have no low-voltage-activated channels. Although acutely isolated neurons provide a good preparation for whole cell voltage-clamp study, dendritic processes are lost during dissociation. To gain information on Ca(2+) channels in dendrites, we thus studied Ca(2+) channels of STN neurons in a slice preparation, focusing on low-voltage-activated channels. In current-clamp recordings, a slow spike was always observed following termination of an injected hyperpolarizing current. The slow spike occurred at resting membrane potentials and was sensitive to micromolar concentrations of Ni(2+), suggesting that it is a low-threshold Ca(2+) spike. Together, our results suggest that STN neurons express low-voltage-activated Ca(2+) channels and several high-voltage-activated subtypes. Our results also suggest the possibility that the low-voltage-activated channels have a preferential distribution to the dendritic processes.

Action Potentials↗

PubMed2000

Chemical constituents of Micromelum minutum. Isolation and structural elucidation of new coumarins.

The chemical constituents of an acetone extract of the stems of Micromelum minutum Wight et Arn (Rutaceae), collected at Nakorn-Rachasima province in Thailand, were studied. Six new coumarins, named micromarin-A (1), -B (2), -C (3), -F (4), -G (5), and -H (6), were isolated along with six known coumarins, and their structures were elucidated by chemical and spectroscopic methods.

Coumarins↗

PubMed2000

Paraneoplastic pemphigus associated with bronchiolitis obliterans.

Paraneoplastic pemphigus (PNP) is an autoantibody-mediated mucocutaneous blistering disease associated with underlying neoplasms. Autoantibodies of PNP bind to the plakin family of cytoplasmic proteins and desmogleins of cell-surface target antigens. We describe a 36-year-old female patient with PNP who had non-Hodgkin's lymphoma, and who developed bronchiolitis obliterans and died of respiratory failure. Autopsy findings confirmed luminal narrowing of bronchioles by scarring, which is a histopathologic features of bronchiolitis obliterans. After the onset of respiratory failure, the reaction of autoantibodies against the plakins detected by immunoprecipitation at the onset of PNP disappeared with negative immunofluorescence within the bronchial epithelium. It is thought that autoantibodies against some of these antigens play a role in causing acute inflammation of the respiratory epithelium. In treating PNP, the possibility of the patient developing the lethal complication bronchiolitis obliterans should be kept in mind. Furthermore, prevention of the initial autoantibody-mediated injury to the respiratory epithelium should be an important treatment goal.

Adult↗

PubMed2000

Vaccination of a refractory essential monoclonal cryoglobulinemia patient with cryoglobulin-pulsed dendritic cells.

We vaccinated a refractory essential monoclonal cryoglobulinemia patient with monocyte-derived DCs (Mo-DCs) pulsed with purified cryoglobulin as a tumor antigen. During the vaccinations, his acrocyanosis improved and we were able to reduce the number of hot baths used to treat his symptoms, with no side effects. Furthermore, cryoglobulin-specific proliferative responses were observed after the vaccination. As there was a recurrence of acrocyanosis after the final vaccination, vaccination with Mo-DCs pulsed with purified cryoglobulin would seem to be a useful treatment for refractory essential monoclonal cryoglobulinemia.

Antigens↗

PubMed2000

WF14865A and B, new cathepsins B and L inhibitors produced by Aphanoascus fulvescens. I. Taxonomy, production, purification and biological properties.

WF14865A and B, novel cathepsins B and L inhibitors, were produced and isolated separately from the culture mycelium of a fungal strain Aphanoascus fulvescens No. 14865. Spectroscopic analysis revealed that both WF14865A and B were composed of trans-epoxysuccinyl moieties, 1-H-imidazole-2-ylamine, and isoleucine or leucine. These compounds inhibited human cathepsins B and L with IC50 values in the range of 8.4 approximately 72nM in vitro. Though their in vitro properties were typical as trans-epoxysuccinyl type inhibitors, they exerted strong bone resorption inhibitory effects in low-calcium-diet-fed mouse model at 3.2 approximately 10 mg/kg.

Animals↗

PubMed2000

[Clinicopathological study of left ventricular remodeling after first acute myocardial infarction].

The morphological characteristics of post-infarction ventricular remodeling were determined by comparison of infarct location and histological changes of noninfarcted myocardium at autopsy. A total of 94 cases of first acute myocardial infarction with clinical courses of 0 to 37 days were studied. Hearts were sliced on the short axis at the level of 1/3 of the distance from the atrioventricular ring to the apex. Wall thicknesses of the infarcted and noninfarcted areas, and the endocardial and epicardial perimeter lengths of the left ventricle were measured. Myocyte diameter and number of myocytes in the noninfarcted area were measured. Infarcts were classified into 3 groups based on infarct location (51 anterior, 22 posterior, and 21 nontransmural circumferential) and each group was further divided according to the clinical course of less than 72 hours or longer. Fifty two patients died within 72 hours. Cardiac rupture was the most common cause of death in the anterior group. Patients in the posterior group chiefly died due to cardiogenic shock and in the circumferential group chiefly died to pump failure. According to the number of stenosed coronary arteries, cardiac rupture was the most common cause of death in single-vessel disease in both anterior and posterior groups (62.1% and 55.6%, respectively). In double-vessel disease, the most common cause of death in the anterior group was still cardiac rupture (50.0%). On the other hand, 50.0% of the posterior group died of cardiogenic shock in double-vessel disease. Patients with triple-vessel disease mainly died due to heart failure in all groups. Wall thickness of the infarcted myocardium was decreased in the anterior group after 72 hours (11.8 +/- 3.5 vs 7.8 +/- 2.5 mm). Endocardial perimeter length was increased in the anterior and circumferential groups (83.6 +/- 25.6 vs 116.3 +/- 29.5 mm, 75.2 +/- 12.0 vs 117.6 +/- 3.1 mm, respectively). Endocardial/epicardial perimeter length ratio increased with longer clinical course in the anterior group. No specific change in wall thickness or perimeter length was found in the posterior group. Noninfarcted wall thickness was preserved in both the anterior and posterior groups. Myocyte diameter and number of myocytes in the noninfarcted area showed no significant difference after 72 hours. The nature of ventricular remodeling differs with infarct location. Ventricular dilation occurred during the clinical course in the anterior group. The transmural and adjacent areas are more important than the remote noninfarcted area in post-infarction remodeling within this period.

Adult↗

PubMed2000

Down-regulation of human telomeric protein TRF1 gene expression during myeloid differentiation in human hematopoietic cells.

The maintenance of telomere length is crucial for cell survival. Recently, it has been indicated that the human telomeric protein TRF1 is involved in the negative feedback mechanism that stabilizes telomere length. We studied TRF1 mRNA expression in hematopoietic cells to clarify the relation between TRF1 and telomerase by semiquantitative reverse transcriptase-polymerase chain reaction. In polymorphonuclear cells and monocytes isolated from peripheral blood, relatively low levels of TRF1 mRNA expression were seen, compared with those of lymphocytes and CD34+. We then assessed TRF1 mRNA expression in CD34+ cells cultured in vitro with growth factors. After 4 weeks of culture, all the cells showed myeloid differentiation, and telomerase activity was down-regulated. TRF1 mRNA was expressed in CD34+ cells but was down-regulated in cells cultured for 4 weeks. We conclude that TRF1 mRNA expression is down-regulated in accordance with telomerase down-regulation during the course of myeloid differentiation.

Antigens, CD34↗

PubMed1999

Production of soluble granulocyte colony-stimulating factor receptors from myelomonocytic cells.

It has been speculated that a soluble form of G-CSFR might be physiologically present in humans, since G-CSFR mRNA that lacks a transmembrane domain has been identified from a human myelomonocytic cell line. Here, we demonstrate human soluble G-CSFR (sG-CSFR) of two different molecular sizes (80 and 85 kDa) on an immunoblot analysis using Abs generated against the amino-terminal, extracellular domain of the full-length G-CSFR. Both isoforms of sG-CSFR were able to bind recombinant human G-CSF (rhG-CSF). RT-PCR analysis with primers targeted outside of the transmenbrane region revealed that membrane-anchored G-CSFR is expressed at all maturation stages of purified myeloid cells, including CD34+CD13+ cells (blasts), CD11b-CD15+ cells (promyelocytes or myelocytes), CD11b+CD15+ cells (metamyelocytes and mature neutrophils), and CD14+ cells (monocytes). On the other hand, sG-CSFR mRNA was detectable in CD11b-CD15+, CD11b+CD15+, and CD14+ cells, but not in the CD34+CD13+ blast population. The serum concentration of both isoforms of sG-CSFR appeared to be correlated with the numbers of neutrophils/monocytes before and after rhG-CSF treatment in normal individuals. Thus, two isoforms of sG-CSFR are physiologically secreted from relatively mature myeloid cells and might play an important role in myelopoiesis through their binding to serum G-CSF.

Amino Acid Sequence↗