Biomedical subjects

S Takada

Publications and source records attributed to S Takada.

At least 91 records · Page 5Linked to original sources

PubMed1998

Monitoring of occupational exposure to dichloromethane by diffuse vapor sampling and urinalysis.

OBJECTIVE: The aim of the present study was to develop valid methods for monitoring of occupational exposure to dichloromethane (DCM). METHODS: Carbon cloth as an adsorbent in diffusive sampling was tested for its capacity to adsorb DCM vapor and to retain adsorbed DCM after termination of the exposure. Urine samples collected from DCM-exposed workers were analyzed for DCM by the head-space technique. After extraction with carbon disulfide, DCM in the cloth was analyzed on a DB-WAX capillary column by flame-ionization detection gas chromatography (FID-GC) and DCM in urine was analyzed by electron-capture detection (ECD)-GC. RESULTS: The diffusive sampling with carbon cloth as an adsorbent is applicable to 4-h monitoring of exposure to up to 100 ppm DCM vapor. DCM concentrations detected in end-of-shift urine samples correlated linearly with time-weighted average DCM concentrations measured in the breathing-zone air of the exposed workers; essentially the same exposure-excretion relationship was obtained by vapor monitoring for the afternoon 4-h period as compared with a whole day (8-h) of vapor monitoring. There was no sex difference in the exposure-excretion relation. CONCLUSIONS: Both personal diffusive sampling (at up to 100 ppm DCM and for up to 4 h) and biological exposure monitoring by urinalysis for DCM are applicable in occupational health as reliable measures of exposure to this chlorinated hydrocarbon solvent.

Air Pollutants, Occupational↗

PubMed1998

Fulminant, CMV-associated, haemophagocytic syndrome following unrelated bone marrow transplantation.

We report a case of haemophagocytic syndrome (HPS) occurring after allogeneic bone marrow transplantation (BMT) for acute promyelocytic leukaemia (APL) in a patient in fourth complete remission (CR). Anti-cytomegalovirus (CMV) antibody (Ab) was negative in this patient before BMT. BMT was performed from an HLA-identical unrelated donor who was positive for CMV Ab. After bone marrow engraftment and haematological recovery, severe acute graft-versus-host disease (GVHD) developed. This patient was treated with methylprednisolone in addition to cyclosporin A (CsA). Acute GVHD showed partial improvement, but CMV antigenaemia was observed. Despite administration of gancyclovir and immunoglobulin, CMV antigenaemia showed no improvement and HPS developed. As no other infections or malignancies were observed, we suspect that CMV infection was the trigger for development of HPS.

Adult↗

PubMed1998

Post-transcriptional control of the level of mRNA by hepatitis B virus X gene in the transient expression system using human hepatic cells.

BACKGROUND: Hepatitis B virus (HBV) infection is closely related to the development of not only acute or chronic hepatitis, but also hepatocellular carcinoma. Among the HBV genes, the X gene has been implicated in the carcinogenicity of this virus as a major causative factor by its ability to activate viral and cellular genes in trans via protein-protein interaction with cellular factors without binding to DNA. RESULTS: To explore the possibility of other functions of the X gene, we examined the effect of X protein on the transient expression system of simian virus 40 (SV40) large T-antigen or chloramphenicol acetyltransferase (CAT) mRNA using SV40 promoter or EF-1alpha (human elongation factor 1alpha) promoter, by co-transfecting an X gene expression plasmid to human hepatic cell lines, HepG2 and Huh7. In contrast to the SV40 promoter-mediated expression, the level of both T-antigen and CAT mRNAs expressed from the EF-1alpha promoter was strikingly decreased by X protein in both hepatic cells. The nuclear run-on assay and the mRNA decay experiment using actinomycin D, indicated that the effect of X protein on the lowering of the level of chimeric mRNA was due to the degradation of mRNA, but not repression of transcriptional initiation. Moreover, this effect was dependent on the 22 bp sequence in the 5' untranslated region of mRNA derived from the EF-1alpha promoter. CONCLUSION: The present data suggest a new function of the X gene to post-transcriptionally control the stability of mRNA through the 5' untranslated region derived from the EF-1alpha promoter in human hepatic cells.

Antigens, Polyomavirus Transforming↗

PubMed1998

Cytoskeletal reorganization by soluble Wnt-3a protein signalling.

BACKGROUND: Wnt-3a is an intercellular signalling molecule that is involved in a variety of morphogenetic events. However, the molecular mechanisms underlying Wnt-3a signalling are poorly understood. We have sought to establish in vitro systems to assay the activity of this protein and investigate its biological roles. RESULTS: We prepared mouse L cells transfected with Wnt-3a cDNA, and found that their beta-catenin protein level was up-regulated. When conditioned medium (CM) was collected from cultures of the transfectants and added to nontransfected L cells, the beta-catenin level of the latter was also increased. Approximately 50% of the Wnt-3a proteins synthesized by the transfectants were secreted into the CM in a soluble form. These secreted Wnt-3a proteins formed an activity gradient in the environment surrounding the transfectants. Then, we studied whether Wnt-3a had any effect on cellular behaviour in vitro. When the CM containing Wnt-3a (W3a-CM) was added to cultures of C57MG mammary epithelial cells, their morphology was altered to exhibit closer intercellular contacts. Immunostaining for various adhesion and cytoskeletal proteins showed that the actin-microfilamental system was re-organized by the W3a-CM treatment. It induced a directional alignment of actin stress fibres and other actin-associated proteins. Moreover, villin, localized only at the perinuclear regions in untreated C57MG cells, was re-distributed to the leading edges of the cells, co-localizing with F-actin, in the presence of Wnt-3a. CONCLUSION: Our findings suggest that Wnt-3a protein, in the soluble form, can act to re-organize cytoskeletal structures.

Actins↗

PubMed1998

Regulation of invasive potential of human prostate cancer cell lines by hepatocyte growth factor.

BACKGROUND: The growth and progression of prostate cancer depends on the stromal-epithelial interaction which is under paracrine control. Hepatocyte growth factor (HGF), produced by mesenchymal cells, is a multifunctional growth factor stimulating the movement and growth of epithelial cells including cancer cells. We therefore assessed the relationship between the invasive potential of prostate cancer and HGF in vitro. METHODS: Three human prostate cancer cell lines were used including PC-3 and DU145 (androgen-independent), and LNCaP (androgen-dependent). We studied the expression of the HGF receptor c-met proto-oncogene (c-met) by Western blot analysis, and also determined the effects of HGF on cell scattering, and the mechanisms of invasion and proliferation, by microscopic observation, the matrigel invasion chamber assay, and the MTT assay. RESULTS: c-met was detected in PC-3 and DU145 cells, but not in the LNCaP cells. There was increased cell motility in the scatter assay and an increased cell invasive potential in the matrigel invasion chamber assay by stimulation with HGF only with DU145 cells. CONCLUSION: HGF plays an important role in the invasion and metastasis of the DU145 cell line through a paracrine mechanism mediated by the c-metreceptor. In the PC-3 cell line, the lack of downstream signal transduction after the c-met receptor is suggested.

Biocompatible Materials↗

PubMed1998

Translocation breakpoint possibly predisposes to nonrandom X-chromosome inactivation in mouse embryos bearing Searle's T(X;16)16H translocation.

To clarify the sequence of events that ultimately achieves the nonrandom inactivation of the paternally inherited X chromosome in postpartum female mice heterozygous for T(X;16)16H, we set out to examine the expression of Xist alleles and the X-linked HMG-lacZ transgene in embryos recovered at the egg cylinder stage. Lack of expression of the Xist(b) allele on the 16X translocation chromosome in the embryonic region of 7.5 d postcoitum (dpc) X16/X(n)Xist(a);16(X)Xist(b)/16 embryos strongly suggested the occurrence of nonrandom inactivation in favor of the normal X chromosome. The simplest explanation would be biased choice, followed by postinactivation selection against genetically unbalanced cells. However, the frequency and distribution of beta-galactosidase-positive cells in X16/X(n)lacZ;16X/16 embryos at 6.5 and 7.5 dpc, together with earlier cytogenetic data, raised an intriguing possibility that the majority of 16X chromosomes were prevented from completing the inactivation process, when they had been chosen to be silenced. Phenotypes of female mice carrying a spontaneous recombination between Xn and 16X in the segment defined by the T16H breakpoint and the X-linked Ta locus suggested that the nonrandomness was brought about by disruption of an X-chromosomal sequence or structure at the translocation breakpoint.

Animals↗

PubMed1998

Wnt signaling from the dorsal neural tube is required for the formation of the medial dermomyotome.

Signals originating from tissues surrounding somites are involved in mediolateral and dorsoventral patterning of somites and in the differentiation of the myotome. Wnt-1 and Wnt-3a, which encode members of the Wnt family of cystein-rich secreted signaling molecules, are coexpressed at the dorsal midline of the developing neural tube, an area adjacent to the dorsomedial portion of the somite. Several lines of evidence indicate that Wnt-1 and Wnt-3a have the ability to induce the development of the medial and dorsal portion of somites, as well as to induce myogenesis. To address whether these Wnt signalings are really essential for the development of somites during normal embryogenesis, we investigated the development of somites in mouse embryos lacking both Wnt-1 and Wnt-3a. Here we demonstrate that the medial compartment of the dermomyotome is not formed and the expression of a lateral dermomyotome marker gene, Sim-1, is expanded more medially in the absence of these Wnt signalings. In addition, the expression of a myogenic gene, Myf-5, is decreased at 9.5 days post coitum whereas the level of expression of a number of myogenic genes in the later stage appeared normal. These results indicate that Wnt-1 and Wnt-3a signalings actually regulate the formation of the medial compartment of the dermomyotome and the early part of myogenesis.

Animals↗

PubMed1998

[Design and development of controlled release of drugs from injectable microcapsules].

Monolithic microcapsules were designed and developed for controlled release of leuprorelin for one month following a single injection. Copoly (DL-lactic/glycolic) acid (PLGA) of copolymer ratio of 75/25 and average molecular weight of 14,000 was suitable for achieving steady serum leuprorelin levels in rats and dogs for 4 weeks. The clinical efficacy of these injectable microcapsules of leuprorelin has been widely proved for prostate cancer, endometriosis, and other sex hormone dependent diseases in about sixty countries. The interaction between the basic functional group of the drug and the carboxylic end group of PLGA was found to be the most important factor in preparing the microcapsules with a small initial burst, as shown with thyrotropin releasing hormone (TRH) and a water-soluble GPIIb/IIIa antagonist (TAK-029).

Animals↗

PubMed1998

Hepatitis B virus DNA is frequently found in liver biopsy samples from hepatitis C virus-infected chronic hepatitis patients.

Human hepatitis B virus (HBV) and hepatitis C virus (HCV) are two major etiologic agents of chronic hepatitis, which is closely related to the development of hepatocellular carcinoma (HCC). A possible involvement of HBV co-infection was investigated in ongoing HCV-related liver diseases in HCV-infected patients. A prevalence of anti-HBc in anti-HCV-positive/HBsAg-negative chronic hepatitis patients and a low copy number of HBV DNA were found in most of the liver biopsy samples of anti-HCV-positive/HBsAg-negative patients. The present data suggest that HBV co-infects frequently with HCV and may play an important role in the development of HCC in the anti-HCV-positive/HBsAg-negative patients with chronic hepatitis.

Adult↗

PubMed1998

[A case report of neoadjuvant intra-arterial injection chemotherapy combined with peripheral blood stem cell reinfusion in an advanced breast cancer patient].

A seventy-one year-old woman suffered from Stage IIIb advanced breast cancer complicated with direct thoracic invasion and skin eruption. An indwelling intra-arterial catheter was inserted into the subclavian artery for the administration of anti tumor agents. After three courses of neoadjuvant chemotherapy combined with G-CSF and/or PBSCT reinfusion, the breast cancer revealed a remarkable size reduction and was absent from direct thoracic and pectoral muscle, invasion within the physical status and visual analysis by CT scan. Thereafter, the patient underwent a radical mastectomy. In the pathological findings of the operation specimen, despite a remarkable tumor collapse, the microscopic invasion remained in the shallow layer of the pectoral muscle. Thus, the patient should be given additional postoperative irradiation. The patients has had six months of stable tumor-free survival since the mastectomy.

Aged↗

PubMed1998

[Incidence of cerebral palsy in Himeji City 1983-1992].

We investigated the incidence of cerebral palsy (CP) in Himeji City with a total population of about 470,000. In 1983-87 the total number of CP patients and the incidence of CP per 1,000 live births were 40 and 1.4, respectively. In 1988-92, the figures were 51 and 2.0. Periventricular leukomalacia was indicated in MRI in 11 out of 40 cases (27.5%) in 1983-87, and in 25 out of 51 (49.0%) in 1988-92. These results suggest that the increase in the incidence of CP mainly depends on changes of medical care for neonates.

Birth Weight↗

PubMed1997

Wnt signalling required for expansion of neural crest and CNS progenitors.

Interactions between cells help to elaborate pattern within the vertebrate central nervous system (CNS). The genes Wnt-1 and Wnt-3a, which encode members of the Wnt family of cysteine-rich secreted signals, are coexpressed at the dorsal midline of the developing neural tube, coincident with dorsal patterning. Each signal is essential for embryonic development, Wnt-1 for midbrain patterning, and Wnt-3a for formation of the paraxial mesoderm, but the absence of a dorsal neural-tube phenotype in each mutant suggests that Wnt signalling may be redundant. Here we demonstrate that in the absence of both Wnt- and Wnt-3a there is a marked deficiency in neural crest derivatives, which originate from the dorsal neural tube, and a pronounced reduction in dorsolateral neural precursors within the neural tube itself. These phenotypes do not seem to result from a disruption in the mechanisms responsible for establishing normal dorsoventral polarity. Rather, our results are consistent with a model in which local Wnt signalling regulates the expansion of dorsal neural precursors. Given the widespread expression of different Wnt genes in discrete areas of the mammalian neural tube, this may represent a general model for the action of Wnt signalling in the developing CNS.

Animals↗

PubMed1997

Cytoplasmic retention of the p53 tumor suppressor gene product is observed in the hepatitis B virus X gene-transfected cells.

It has been suggested that hepatitis B virus (HBV) X gene activates X gene expression by disrupting the function of p53 tumor suppressor gene (Takada et al., 1996). To find out their connection, effect of X protein expression on the nuclear localization of p53 protein in human hepatoma cells was examined by the immunofluorescent double-staining technique. The location of transiently-expressed p53 protein was examined in X gene-transfected cells, where X protein was detected in the cytoplasm. The nuclear location of transiently-expressed p53 protein was changed to the cytoplasm by X protein co-expression. Endogenous p53 protein was also observed in the cytoplasm by X protein expression. The transcriptional activation domain of X protein and the carboxy-terminal region of p53 protein were found mutually responsible for the cytoplasmic retention of p53 protein in X gene-transfected cells. Therefore, the cytoplasmic retention of p53 protein may be closely correlated to the function of X protein expressed in transfected cells.

Biological Transport↗

PubMed1997

Transcription properties of a cell type-specific TATA-binding protein, TRF.

Eukaryotic cells are thought to contain a single TATA-binding protein (TBP) that directs transcription by cellular RNA polymerases. Here we report a cell type-specific TBP-related factor (TRF) that can form a stable TRF/IIA/IIB TATA DNA complex and substitute for TBP in directing RNA polymerase II transcription in vitro. Transfection studies reveal that TRF can differentially mediate activation by some enhancer proteins but not others. Like TBP, TRF forms a stable complex containing multiple novel subunits, nTAFs. Antibody staining of embryos and polytene chromosomes reveals cell type-specific expression and gene-selective properties consistent with the shaker/male sterile phenotype of trf mutants. These findings suggest TRF is a homolog of TBP that functions to direct tissue- and gene-specific transcription.

Animals↗

PubMed1997

Characterization of a specific region in the hepatitis B virus enhancer I for the efficient expression of X gene in the hepatic cell.

Hepatitis B virus (HBV) enhancer I has been shown to consist of several cis-acting sequences for the HBV gene expression efficiently in certain types of cells. Transcriptional regulation of HBV X gene mediated by enhancer I might be one of the mechanisms by which HBV obtains hepatotropism. By mutagenesis analysis of enhancer I function in the enhancer I/X gene promoter complex, we characterized a specific transcriptional regulatory region (designated as a LSR element, nt 989-1030) of enhancer I for the X gene promoter by means of the transient transfection technique using hepatic and nonhepatic cells. Based on the analysis of protein factors interacting with the LSR element, liver-enriched transcriptional factors, HNF3 and HNF4 or retinoid X receptor alpha (RXR alpha), are probably implicated in the activity of enhancer I for the efficient expression of X gene through their interaction with the LSR element in the hepatic cell. Furthermore, the isolated LSR element was demonstrated to function alone as a specific cis-acting element and to be able to activate transcription from the X gene promoter efficiently in the hepatic cell in an orientation-independent manner.

Base Sequence↗

PubMed1997

Neural activity and intracellular Ca2+ mobilization in the CA1 area of hippocampal slices from immature and mature rats during ischemia or glucose deprivation.

To investigate the correlation between neural activity and intracellular Ca2+ ([Ca2+]i) mobilization in immature and adult brain during ischemia (hypoxia and glucose deprivation) and deprivation of glucose, hippocampal slices were prepared from 7-, 10-day-old and adult rats. Population spikes (PS) and antidromic responses (AR) were recorded in the pyramidal cell layer of the CA1 area as an index of neural function. [Ca2+]i mobilization of the stratum radiatum in the CA1 area was measured using the fluorescent dye fura-2 AM. The rise in [Ca2+]i occurred earlier in the adult animal and the decay times for the orthodromic PS and antidromic responses were shorter in the adult during ischemia. The field potentials and antidromic responses decreased substantially prior to the elevation of [Ca2+]i in both developing and adult brains. Furthermore, ATP levels decreased substantially before the elevation of [Ca2+]i during ischemia. These results suggest that neural activity and intracellular Ca2+ homeostasis in the immature rats brain are more resistant to energy failure than adult rats and that neuronal activity in the developing and adult brain is impaired initially by energy depletion during ischemia. In the immature animal, during glucose deprivation, the antidromic responses were slowly decayed or even failed to extinguish and [Ca2+]i levels were maintained for a longer period or even failed to rise in spite of the rapid loss of PS. Furthermore, ATP levels were well preserved at the time of PS loss. These results agree well with our previous reports showing that glucose plays an important role in the preservation of synaptic transmission in addition to its major function as an energy substrate.

Aging↗

PubMed1997

Transcriptional activation of the human c-myc gene by simian virus 40 large T antigen without binding to p53 and RB proteins in the transient expression system.

Transcriptional activation of the human c-myc gene by SV40 large T antigen was examined using HepG2 cells by co-transfecting a T antigen expression plasmid with a myc-CAT construct containing the 2.3-kb upstream region from the P1 promoter and the P2 promoter region fused to the CAT gene. T antigen increased the basal activity of the P2 promoter region containing the E2F binding site, but both the P2 promoter region and the upstream region from the P1 promoter were important for overall activation by T antigen. CAT assay using mutated T antigen lacking p53 or the RB binding site indicated that p53 or RB was not mainly involved in transcriptional activation of the c-myc gene. It appears that activation of the c-myc gene by T antigen is probably dependent upon E2F and a cellular factor through a mechanism which is independent of binding of T antigen to p53 and RB.

Antigens, Polyomavirus Transforming↗

PubMed1997

The Chlamydomonas reinhardtii ODA3 gene encodes a protein of the outer dynein arm docking complex.

We have used an insertional mutagenesis/ gene tagging technique to generate new Chlamydomonas reinhardtii mutants that are defective in assembly of the uter ynein rm. Among 39 insertional oda mutants characterized, two are alleles of the previously uncloned ODA3 gene, one is an allele of the uncloned ODA10 gene, and one represents a novel ODA gene (termed ODA12). ODA3 is of particular interest because it is essential for assembly of both the outer dynein arm and the outer dynein arm docking complex (ODA-DC) onto flagellar doublet microtubules (Takada, S., and R. Kamiya. 1994. J. Cell Biol. 126:737- 745). Beginning with the inserted DNA as a tag, the ODA3 gene and a full-length cDNA were cloned. The cloned gene rescues the phenotype of oda3 mutants. The cDNA sequence predicts a novel 83. 4-kD protein with extensive coiled-coil domains. The ODA-DC contains three polypeptides; direct amino acid sequencing indicates that the largest of these polypeptides corresponds to ODA3. This protein is likely to have an important role in the precise positioning of the outer dynein arms on the flagellar axoneme.

Amino Acid Sequence↗