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Biomedical subjects

T Tsukada

Publications and source records attributed to T Tsukada.

At least 73 records · Page 4Linked to original sources
PubMed1997

A fraction unresponsive to growth inhibition by TGF-beta among the high-proliferative potential progenitor cells in bone marrow of p53-deficient mice.

Transforming growth factor-beta (TGF-beta) has been found to block the progression of the cell-cycle by up-regulating a Cdk inhibitor, p15, only in epithelial cells; on the other hand, wild-type p53 was shown to activate transcriptionally the gene for another Cdk inhibitor, p21. The regulatory effects of TGF-beta on hematopoietic tissues is poorly understood. Hence, we investigated the effect of TGF-beta on hematopoietic progenitor cells in p53-deficient mice to determine whether an inhibitory signal from TGF-beta is linked to p53 in hematopoietic regulation. We found that the proliferation of megakaryocyte-progenitors (CFU-Mk) in our wild-type mice was markedly inhibited by TGF-beta. Contrary to an earlier report, an erythroid and a granulocyte-macrophage progenitor, stimulated by IL-3, were not significantly inhibited, whereas TGF-beta also completely inhibited the growth of high-proliferative potential progenitor cells (HPP-CFC) in the marrow of mice with 5-fluorouracil (5FU), as reported. It is interesting that in the p53-deficient mice, the inhibitory action of TGF-beta on the HPP-CFC was incompletely abolished. The response curve we obtained for graded doses of TGF-beta suggests that there is, at least, a subpopulation of HPP-CFC which is less sensitive to the regulation by TGF-beta. In contrast to HPP-CFC, the CFU-Mk, which TGF-beta inhibited only in wild-type mice not treated with 5FU, remained inhibited in the p53-deficient strain. Thus, HPP-CFC might be regulated by TGF-beta through their signal pathways which are linked to p53.

Animals↗
PubMed1997

Mechanical agitation induces gene expression of NOR-1 and its closely related orphan nuclear receptors in leukemic cell lines.

NOR-1, NGFI-B and Nurr1 are closely related transcription factors that constitute a distinct subfamily within the nuclear receptor superfamily. Genes for these proteins are immediate-early genes, and are inducible in diverse cell types by various stimuli. In the present study, we investigated the effect of mechanical agitation on the gene expression of these transcription factors in cultured suspension cells by the quantitative reverse transcription-polymerase chain reaction. We found that mechanical agitation transiently induced NOR-1, NGFI-B and Nurr1 mRNAs in several leukemic cell lines in a dose-dependent manner. This induction was most pronounced in the HL-60 promyelocytic leukemia cell line, but also occurred to a lesser extent in other cell lines including KG-1, THP-1 and U937 cells. The induction was attenuated by serum or albumin, which are shear stress protectants for suspension culture cells. These reagents did not suppress forskolin-induced NOR-1 gene expression. These findings suggest the involvement of fluid shear stress in agitation-induced immediate-early gene expression. Since even moderate agitation could cause the induction, investigators should be cautious when evaluating the expression of immediate-early genes in some leukemic cell lines.

DNA-Binding Proteins↗
PubMed1997

Effects of rapamycin on apoptosis of rheumatoid synovial cells.

In the present study, we investigated the effects of an immunosuppressant, rapamycin, on bcl-2 expression and the susceptibility of human rheumatoid synovial fibroblasts to Fas-mediated apoptosis. Rapamycin treatment down-regulated bcl-2 expression on rheumatoid synovial cells in a dose-dependent manner. In contrast, Fas antigen expression was not influenced by rapamycin treatment. Rapamycin treatment also enhanced the susceptibility of rheumatoid synovial cells to anti-Fas monoclonal antibody-mediated apoptosis. Our results suggest that rapamycin augments the sensitivity of rheumatoid synovial fibroblasts to apoptosis by down-regulating bcl-2 expression. This pharmacological alteration of sensitivity to apoptosis in the rheumatoid synovium may represent a new therapeutic approach for rheumatoid arthritis.

Adult↗
PubMed1997

Differential expression of NGFI-B and RNR-1 genes in various tissues and developing brain of the rat: comparative study by quantitative reverse transcription-polymerase chain reaction.

NGFI-B and RNR-1 are closely related transcription factors that constitute a distinct subclass within the steroid/thyroid hormone receptor superfamily. They have been implicated in neuronal differentiation, neuroendocrine regulation of adrenocortical function and T-cell apoptosis. In this study, we measured and compared NGFI-B and RNR-1 mRNA levels in various adult rat tissues and in the developing rat brain by means of the quantitative reverse transcription-polymerase chain reaction. The use of RNA standards synthesized in vitro allowed direct comparison of the amount of the transcripts of these two genes. We demonstrated that the transcripts of both genes were present in all tissues examined although the expression levels widely varied. We found the highest constitutive expression of both genes in the pituitary. High levels of NGFI-B were also expressed in the cerebral cortex, muscle, ventral prostate, thymus and adrenal glands, whereas high levels of RNR-1 expression were restricted to the pituitary and cerebral cortex. These findings were consistent with the notion that NGFI-B and RNR-1 are involved in various signal transduction systems in diverse cell types. The amount of NGFI-B mRNA was greater than that of RNR-1 mRNA in all adult rat tissues, with the highest ratio of NGFI-B relative to RNR-1 expression in the muscle and leukocytes. In contrast, fetal rat brain showed relatively high RNR-1 gene expression. These findings suggested that the NGFI-B and RNR-1 genes are differentially expressed in a tissue-specific and developmentally regulated manner.

Adrenal Glands↗
PubMed1997

Multiple endocrine neoplasia type 1 presented with manic-depressive disorder: a case report with an identified MEN1 gene mutation.

We report a case of multiple endocrine neoplasia type 1 who had repeated hypoglycemic episodes and had previously been diagnosed with bipolar manic-depressive disorder. The patient had a positive family history of multiple endocrine neoplasia type 1 and had multiple pancreatic endocrine tumors, hyperparathyroidism and possibly a pituitary tumor. The pancreatic tumors were resected by subtotal pancreatectomy and examined by histochemical staining and gene analysis. The tumor cells were positive for immunoreactive insulin and glucagon. A microsatellite polymorphism analysis revealed loss of heterozygosity on 11q13 in the tumors. By polymerase chain reaction-based nucleotide sequencing, we identified a germline mutation 483del2 of the MEN1 gene in the normal pancreatic tissue of the patient. This mutation causes a shift of the reading frame of menin mRNA at codon 125. It seems that the wild type allele of the MEN1 gene had been lost in the tumor cells whereas the mutant allele remained intact. This is the first identified MEN1 gene mutation in Japanese families and is different from all MEN1 gene mutations reported previously.

Adult↗
PubMed1997

Germline mutations of the MEN1 gene in Japanese kindred with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant familial cancer syndrome. The responsible gene MEN1 has recently been isolated, and its germline mutations have been identified in affected individuals in the United States, Canada and Europe. We screened for MEN1 mutations by direct nucleotide sequencing of all protein-coding regions, and identified five distinct germline mutations in five among six Japanese kindreds with familial MEN1 or familial hyperparathyroidism. The mutations were dispersed across the gene. These findings suggest that, because of the absence of an obvious founder effect, the entire MEN1 gene region should be examined for germline mutations in the probands of MEN1 and related syndromes in Japanese families.

DNA, Neoplasm↗
PubMed1997

Expression of the putative transcription factor NOR-1 in the nervous, the endocrine and the immune systems and the developing brain of the rat.

NOR-1 is a novel member of the NGFI-B/RNR-1 subfamily within the nuclear receptor superfamily, and has been implicated in signal transduction mediated by various second messengers. To investigate the physiological role of NOR-1, we examined its gene expression in various adult rat tissues and developing rat brain by the quantitative reverse transcription-polymerase chain reaction using in vitro synthesized RNA as an internal standard. The NOR-1 gene was expressed in all tissues examined, but predominantly in the cerebral cortex and pituitary glands. Thymus, adrenal glands, spleen, epididymis, submandibular glands and deferent ducts showed moderate expression. In the brain, NOR-1 gene expression was developmentally regulated, with the peak levels on gestational day 18. These findings suggest a ubiquitous role of NOR-1 in signal transduction in diverse tissues. These findings also suggest that the nervous, endocrine and immune systems may be highly exposed to NOR-1-inducing stimuli under normal conditions in adult rats. Developing rat brain cells may most frequently receive the relevant signal on day 18 of gestation.

Animals↗
PubMed1997

Effect of intraluminal pressure on the intimal thickening in injured rabbit carotid arteries in an organ-culture system.

We developed an organ culture system in order to examine the effect of intraluminal pressure on intimal thickening in injured arteries. After endothelial denudation, an excised rabbit common carotid artery was incubated at 37 degrees C in a glass bottle perfused with Dulbecco's modified Eagle medium containing 10% fetal calf serum at a constant flow rate of 6 ml/h at various static pressure of 60, 95, 130, 165, or 200 cmH2O. Intimal thickening, which consisted of smooth muscle cells and extracellular matrix, increased in a time- and pressure-dependent manner up to 130 cmH2O. Excessive pressured (165 and 200 cmH2O), however, caused necrosis in the media. These results suggest that a rise in intraluminal pressure accelerates intimal thickening in injured arteries.

Animals↗
PubMed1997

Signal transduction of granulocyte macrophage-colony stimulating factor in a human endothelium-derived cell line.

Granulocyte macrophage-colony stimulating factor (GM-CSF) regulates the growth and differentiation of hematopoietic cells and is also involved in angiogenesis. The induction of protein tyrosine phosphorylation is critical for cytokines and growth factor-mediated signal transduction. The protein tyrosine kinase (PTK), JAK2 is involved in signaling through a number of cytokine receptors, including GM-CSF receptors. In the present study, we investigated the effect of GM-CSF on the cell cycle and protein tyrosine phosphorylation in a human endothelial cell-derived cell line, EA.hy 926 cells. GM-CSF induced the cell cycle progression and tyrosine phosphorylation of cellular proteins including JAK2 kinase in EA.hy 926 cells. Herbimycin A, a PTK inhibitor, completely blocked the GM-CSF-induced cell cycle progression, protein tyrosine phosphorylation and JAK2 kinase activation in EA.hy 926 cells. Our results demonstrate that protein tyrosine phosphorylation and JAK2 kinase activation are closely related to the GM-CSF-mediated signal transduction and growth in vascular endothelial cells, and suggest the efficacy of herbimycin A in controlling angiogenesis.

Benzoquinones↗
PubMed1997

[Evaluation of intramyocardial coronary flow velocity pattern before and after surgical repair of Bland-White-Garland syndrome by pulsed Doppler echocardiography].

Anomalous origin of the left main coronary artery from the pulmonary artery (Bland-White-Garland syndrome) is a rare congenital anomaly. Intramyocardial coronary flow dynamics by pulsed Doppler echocardiography were studied in three patients with this syndrome who underwent surgical repair by Hamilton's method. Before surgery, the intramyocardial flow at the ventricular septum showed a retrograde velocity pattern which had two peaks in systole and diastole in all patients. After surgery, two patients with successful repair showed a biphasic intramyocardial flow pattern which consisted of retrograde and antegrade flows in systole and diastole, respectively. In contrast, one patient who had a residual shunt between the left coronary artery and the pulmonary artery showed a biphasic pattern which had antegrade flow in systole and retrograde flow in diastole. These results may suggest that the evaluation of postoperative intramyocardial coronary flow velocity pattern by pulsed Doppler echocardiography is useful for detecting a residual shunt after surgical repair of Bland-White-Garland syndrome.

Adult↗
PubMed1996

Structure, mapping and expression of a human NOR-1 gene, the third member of the Nur77/NGFI-B family.

We identified a human homologue of NOR-1 (neuron-derived orphan receptor) from the fetal brain. There are two transcripts for human NOR-1, encoding 626 amino acid residues with a calculated molecular mass of 68 kDa. The high homology between hNOR-1, mNur77/rNGFI-B/hTR3, and mNurr1/rRNR-1/hNOT indicated that these three orphan receptors form a distinct subfamily within the steroid/thyroid receptor superfamily. Human NOR-1 mRNA was detected in the adult heart and skeletal muscle as well as in the fetal brain, indicating that its expression is not restricted to events that occur during neural development. The hNOR-1 gene is more than 35 kilobases long and interrupted by seven introns. The exon-intron structure of the gene is generally conserved when compared with the steroid/thyroid receptor superfamily and is remarkably similar to that of the Nur77/NGFI-B genes. This suggests that the Nur77/NGFI-B family has evolved from a common ancestral gene. Fluorescence in situ hybridization (FISH) revealed that the gene is located on chromosome 9q.

Amino Acid Sequence↗
PubMed1996

Decrease in neuron-restrictive silencer factor (NRSF) mRNA levels during differentiation of cultured neuroblastoma cells.

Non-neuronal cells and undifferentiated neuronal progenitors express the neuron-restrictive silencer factor (NRSF), a silencer protein which represses neuronal gene transcription in these cell types. Neuroblastoma, a childhood tumor of neuroectodermal origin, shares some biological properties with neuronal progenitor cells and can acquire neuronal phenotypes in response to a variety of agents, including cyclic AMP and staurosporine. We report here that NRSF mRNA content was markedly decreased in a human neuroblastoma cell line following differentiation induced by staurosporine plus cyclic AMP, with a concomitant increase in mRNA levels of synapsin I, whose expression is restricted to neuronal cell types. Our novel finding suggests that NRSF expression is related to an undifferentiated state and regarded as a biochemical marker of neuronal differentiation in neuroblastoma cells.

Actins↗
PubMed1996

Human CAAF1 gene--molecular cloning, gene structure, and chromosome mapping.

We have isolated and characterized a cDNA and the gene of the human homologue of CAAF1, a novel member of the S100 calcium-binding protein family. The 276-bp open reading frame encoded a 92-amino acid polypeptide with a predicted molecular mass of 10,575 Da. The deduced amino acid sequence of human CAAF1 showed 66% homology to bovine CAAF1. The human CAAF1 gene consisted of three exons, with the two EF hand motifs of the CAAF1 protein separately encoded by exons 2 and 3. This gene was expressed at a high level in polymorphonuclear leukocytes and at an intermediate level in esophageal mucosa. The tissue distribution of CAAF1 mRNA was different from that of other S100 proteins. Direct R-banding fluorescence in situ hybridization revealed that the human CAAF1 gene was mapped to chromosome 1q21.2-q22, where most of the S100 genes form a cluster.

Amino Acid Sequence↗
PubMed1996

A follistatin-like gene, mac25, may act as a growth suppressor of osteosarcoma cells.

mac25, a retinoic acid-inducible gene that is expressed at high levels in senescent epithelial cells, was initially cloned as a gene that is differentially expressed in meningioma. Although the homology of its product with members of family of insulin-like growth factor-binding proteins was suggested, the product also exhibits strong homology to follistatin, an activin-binding protein. However, a domain corresponding to the carboxyl terminus of follistatin is not found in mac25. The carboxyl-terminally truncated form of follistatin, generated by alternative splicing, has stronger activin-binding activity than the complete form. This result suggests that mac25 might act as an activated follistatin. Clonal growth of a p53-deficient osteosarcoma cell line was strongly inhibited when the murine mac25 gene, as well as the p53 gene, was introduced. Resembling activins that belong to the transforming growth factor-beta (TGF-beta) superfamily, mac25 and p53 might associate with similar but distinct targets, namely cyclin-dependent kinase inhibitors. However, there is no evidence for compensation of p53 function by mac25 in the development of p53-deficient mice, as judged from the pattern of expression of mac25 in mice. mac25 might act as a tumor suppressor, modulating signaling of the TGF-beta family, as does alpha-inhibin.

Amino Acid Sequence↗
PubMed1996

Wegener's granulomatosis overlapped with Takayasu arteritis.

A 27-year-old woman presented with destructive scleritis of the left eye with subcutaneous haemorrhage and swelling of the lower eyelid. She had experienced recurrent nasal bleeding for the last six years, and chronic sinusitis resulting in the destruction of the nasal septum and left maxillary sinus. Nasal mucosal biopsies demonstrated granuloma formation with no evidence of vasculitis. The level of serum cytoplasmic anti-neutrophil cytoplasm antibody (c-ANCA) was significantly increased. Furthermore, multiple sites of complete occlusions were detected in the left subclavian and common carotid arteries by subtraction angiography and MRI. We describe a case of Wegener's granulomatosis overlapped with Takayasu arteritis, which, to our knowledge, has not been previously reported.

Adult↗
PubMed1996

Long-term regulation of synapsin I gene expression and neuronal morphology by cyclic AMP and low-dose staurosporine.

We examined the phenotypic changes of neuroblastoma cells chronically treated with cAMP and nanomolar concentrations of staurosporine. These agents, given together, produced cells with a neuronal morphology and a delayed increase (approximately 10 days) in synapsin I mRNA levels. Dopamine-beta hydroxylase mRNA was upregulated within 24 h. We provide evidence that low-dose staurosporine acts cooperatively with cyclic AMP in the acquisition of mature neuronal phenotypes.

Adenylyl Cyclases↗
PubMed1996

The effects of the immunosuppressant rapamycin on the growth of rheumatoid arthritis (RA) synovial fibroblast.

RA is a chronic inflammatory disease characterized by mononuclear cell infiltration and the overgrowth of synovial fibroblast. This invasive growth of synovial tissues corresponds with the progressive destruction of articular cartilage and bone. Several immunosuppressive agents, such as cyclophosphamide, cyclosporin A and mizoribine, have been clinically used to control disease progression, though relatively little is known of their effects on rheumatoid synovium. Rapamycin exhibits a strong immunosuppressive activity by acting on T cell signalling pathways. In the present study we examined the effects of rapamycin on the growth of synovial fibroblast isolated from RA patients. Platelet-derived growth factor (PDGF) is a potent growth factor in synovial fibroblasts isolated from RA patients. PDGF and serum stimulation resulted in a rapid phosphorylation of tyrosine and activation of mitogen-activated protein kinase (MAP kinase), 70-kD-S6 kinase (P70S6k) and 90-kD-S6 kinase (P90rsk). Rapamycin, a macrolide immunosuppressant, inhibited completely growth factor-induced synovial fibroblast proliferation and P70S6k activation. In contrast, tyrosine phosphorylation and activation of MAP kinases and P90rsk were not influenced by rapamycin treatment. Our data demonstrate that growth factor-mediated P70S6k activation is closely related to the growth of synovial fibroblast, and suggest the efficacy of rapamycin for controlling synovial hyperplasia in RA.

Arthritis, Rheumatoid↗