PubMed Health⌕ Search

Biomedical subjects

T Yuasa

Publications and source records attributed to T Yuasa.

At least 19 recordsLinked to original sources
PubMed1998

Potential role of cbfa1, an essential transcriptional factor for osteoblast differentiation, in osteoclastogenesis: regulation of mRNA expression of osteoclast differentiation factor (ODF).

The role of Cbfa1 (core binding factor alpha1), an essential transcriptional factor for osteoblast differentiation, in osteoclastogenesis was investigated in vitro and in vivo using Cbfa1-deficient calvarial cells and mice. Co-cultures of calvarial cells isolated from embryos with three different Cbfa1 genotypes (Cbfa1+/+, Cbfa1+/- and Cbfa1-/-) and normal spleen cells generated TRAP-positive multinucleated osteoclast-like cells (OCLs) in response to 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] and dexamethasone, but the number and bone-resorbing activity of OCLs formed in co-culture with Cbfa1-/- calvarial cells were significantly decreased in comparison with those formed in co-cultures with Cbfa1+/+ or Cbfa1+/- calvarial cells. The expression of osteoclast differentiation factor/osteoprotegerin ligand (ODF/OPGL) mRNA was increased by the treatment with 1alpha, 25(OH)2D3 and dexamethasone in calvarial cells from Cbfa1+/+ and Cbfa1+/- mouse embryos, but not from Cbfa1-/- embryos. In contrast, the expression of osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF) mRNA was inhibited by 1alpha,25(OH)2D3 and dexamethasone similarly in all three types of calvarial cells. ODF/OPGL and OPG/OCIF mRNAs were highly expressed in the tibia and femur of Cbfa1+/+ and Cbfa1+/- embryos. In the tibia and femur of Cbfa1-/- embryos, however, ODF/OPGL mRNA was undetectable and the expression of OPG/OCIF mRNA was also decreased compared with those in Cbfa1+/+ and Cbfa1+/- embryos. These results suggested that Cbfa1 is somehow involved in osteoclastogenesis through regulation of ODF/OPGL.

Animals↗
PubMed1998

Tumor necrosis factor signaling to stress-activated protein kinase (SAPK)/Jun NH2-terminal kinase (JNK) and p38. Germinal center kinase couples TRAF2 to mitogen-activated protein kinase/ERK kinase kinase 1 and SAPK while receptor interacting protein associates with a mitogen-activated protein kinase kinase kinase upstream of MKK6 and p38.

Tumor necrosis factor (TNF) elicits a diverse array of inflammatory responses through engagement of its type-1 receptor (TNFR1). Many of these responses require de novo gene expression mediated by the activator protein-1 (AP-1) transcription factor. We investigated the mechanism by which TNFR1 recruits the stress-activated protein kinases (SAPKs) and the p38s, two mitogen-activated protein kinase (MAPK) families that together regulate AP-1. We show that the human SPS1 homologue germinal center kinase (GCK) can interact in vivo with the TNFR1 signal transducer TNFR-associated factor-2 (TRAF2) and with MAPK/ERK kinase kinase 1 (MEKK1), a MAPK kinase kinase (MAPKKK) upstream of the SAPKs, thereby coupling TRAF2 to the SAPKs. Receptor interacting protein (RIP) is a second TNFR signal transducer which can bind TRAF2. We show that RIP activates both p38 and SAPK; and that TRAF2 activation of p38 requires RIP. We also demonstrate that the RIP noncatalytic intermediate domain associates in vivo with an endogenous MAPKKK that can activate the p38 pathway in vitro. Thus, TRAF2 initiates SAPK and p38 activation by binding two proximal protein kinases: GCK and RIP. GCK and RIP, in turn, signal by binding MAPKKKs upstream of the SAPKs and p38s.

Binding Sites↗
PubMed1998

Phenotype variation correlates with CAG repeat length in SCA2--a study of 28 Japanese patients.

Spinocerebellar ataxia-2 (SCA2) is an autosomal dominant ataxia caused by an abnormal CAG repeat expansion in a novel gene on chromosome 12q24.1. The size of the mutant allele is unstable during transmission, and correlates inversely with age at onset. We studied eight Japanese SCA2 families, including 28 patients, to assess the effect of repeat length on the phenotype features of SCA2. Frequencies of slow eye movements (SEM), reflex activity, dementia, choreiform movements, and axial tremor correlated significantly with CAG repeat size. Parkinsonism was seen in a man homozygote for SCA2 mutation. The clinical variety of SCA2 is apparently influenced by the size of the mutant allele, as is the case in other CAG repeat disorders.

Adolescent↗
PubMed1998

Association of tyrosine phosphatases SHP-1 and SHP-2, inositol 5-phosphatase SHIP with gp49B1, and chromosomal assignment of the gene.

We have analyzed the molecules participating in the inhibitory function of gp49B1, a murine type I transmembrane glycoprotein expressed on mast cells and natural killer cells, as well as the chromosomal location of its gene. As assessed by SDS-polyacrylamide gel electrophoresis and immunoblot analysis, tyrosine-phosphorylated, but not nonphosphorylated, synthetic peptides matching each of the two immunoreceptor tyrosine-based inhibitory motif (ITIM)-like sequences found in the cytoplasmic portion of gp49B1 associated with the approximately 65-kDa tyrosine phosphatase SHP-1 and approximately 70-kDa SHP-2 derived from RBL-2H3 cells. In addition, the phosphotyrosyl peptide matching the second ITIM-like sequence also bound the approximately 145-kDa inositol polyphosphate 5-phosphatase SHIP. Thus, it has been strongly suggested that the inhibitory nature of gp49B involves the recruitment of SHP-1, SHP-2, and SHIP for the delivery of inhibitory signal to the cell interior upon phosphorylation of tyrosine residues in their ITIMs. The gp49B gene has been found to be in the juxtaposition of its cognate gene, gp49A. The gene pair was shown to locate in the B4 band of mouse chromosome 10. In this region, no conserved linkage homology to human chromosome 19, where the genes for killer cell inhibitory receptors are found, has been identified.

Animals↗
PubMed1998

Progressive atrophy of cerebellum and brainstem as a function of age and the size of the expanded CAG repeats in the MJD1 gene in Machado-Joseph disease.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disease characterized by cerebellar ataxia associated to varying degrees with pyramidal signs, extrapyramidal signs, or peripheral amyotrophy. It is caused by unstable expansion of the CAG repeat in the MJD1 gene on chromosome 14q32.1. To determine how the neurodegenerative process in the central nervous system of patients with MJD correlates with the size of expanded CAG repeats in the MJD1 gene and other factors, we performed detailed quantitative analyses of findings of magnetic resonance imaging of the central nervous system of 21 patients with MJD of various ages and with various sizes of expanded CAG repeats. We found that atrophy of the brainstem and cerebellar vermis in MJD patients is closely correlated not only with the size of expanded CAG repeat in the MJD1 gene but also with patient age, which suggests that the neurodegenerative process in MJD is regulated by the size of expanded CAG repeats as well as by the patient age.

Adult↗
PubMed1998

The O6-methylguanine-DNA methyltransferase from the hyperthermophilic archaeon Pyrococcus sp. KOD1: a thermostable repair enzyme.

The enzyme O6-methylguanine-DNA methyltransferase (MGMT) is the most common form of cellular defense against the biological effects of O6-methylguanine (O6-MeG) in DNA. Based on PCR amplification using primers derived from conserved amino acid sequences of MGMTs from 11 species, we isolated the DNA region coding for MGMT from the hyperthermophilic archaeon Pyrococcus sp. KOD1. The MGMT gene from KOD1 (mgtk) comprises 522 nucleotides, encoding 174 amino acid residues; its product shows considerable similarity to the corresponding mammalian, yeast and bacterial enzymes, especially around putative methyl acceptor sites. Phylogenetic analysis of MGMTs showed that archaeal MGMTs were grouped with their bacterial counterparts. The location of the MGMT gene on the KOD1 chromosome was also determined. The cloned KOD1 MGMT gene was overexpressed using the T7 RNA polymerase expression system, and the recombinant protein was purified by ammonium sulfate fractionation, heat treatment, ion-exchange chromatography and gel filtration chromatography. The purified recombinant protein was assayed for its enzyme activity by monitoring transfer of [3H]methyl groups from the substrate DNA to the MGMT protein; the activity was found to be stable at 90 degrees C for at least 30 min. When the mgtk gene was placed under the control of the lac promoter and expressed in the methyltransferase-deficient Escherichia coli strain KT233 (delta ada, delta ogt) cells, a MGMT was produced. The enzyme was functional in vivo and complemented the mutant phenotype, making the cells resistant to the cytotoxic properties of the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine.

Amino Acid Sequence↗
PubMed1998

Improved efficiency of energy transfer to external work in chronic cardiomyoplasty based on the pressure-volume relationship.

OBJECTIVE: Cardiomyoplasty is a surgical procedure to support the failing heart, in which a burst-stimulated latissimus dorsi muscle flap is transposed and wrapped around the ventricles. The effect of dynamic cardiac compression, implemented as cardiomyoplasty, on left ventricular performance remains controversial; the mechanism by which clinical symptoms are improved remains unclear. To investigate the mechanism for improvement of patients' symptoms, it is important to evaluate the effects of cardiomyoplasty on left ventricular energetics and on left ventricular systolic and diastolic function. We therefore evaluated the efficiency of energy transfer from the native pressure-volume area to external work under conditions of 1:3 skeletal muscle burst pacing in an animal model with chronic heart failure. METHODS: In seven Merino-Wether sheep, cardiomyoplasty was performed after stable heart failure was induced by staged coronary embolizations (ejection fraction < 35%). Hemodynamic assessment including the assessment of the pressure-volume relationship was performed 8 weeks after cardiomyoplasty when the latissimus dorsi muscle was fully trained. Instantaneous left ventricular pressure and volume were measured with a catheter-tipped manometer and a conductance catheter during steady-state conditions and after a transient inferior vena cava occlusion. The effect of dynamic cardiac compression on left ventricular systolic function was assessed by comparing pre-assisted and assisted beats and on diastolic function by comparing assisted and post-assisted beats. RESULT: The slope of the end-systolic pressure-volume relationship decreased by 30.5% +/- 27.8% (p = 0.02) during assisted beats. However, left ventricular pump performance improved by increasing stroke volume and external work by 35.9% +/- 36.0% (p = 0.03) and 9.7% +/- 6.8% (p = 0.03), respectively, resulting in a reduction of the volume intercept. As a result, the end-systolic pressure-volume relationship shifted to the left. The efficiency of energy transfer from the native pressure-volume area to the overall external work improved by 7.6% +/- 8.2% (p = 0.04). Cardiomyoplasty did not affect the time constant of left ventricular isovolumic pressure decline or the maximal rate of pressure decay, which suggested that cardiomyoplasty did not affect left ventricular relaxation. CONCLUSIONS: Dynamic cardiac compression in the form of cardiomyoplasty enhanced left ventricular pump performance without interrupting left ventricular filling. The ratio of energy transfer from the native pressure-volume area to the overall external work suggests a myocardial oxygen-sparing effect of cardiomyoplasty.

Animals↗
PubMed1998

Expression of uroplakin Ib and uroplakin III genes in tissues and peripheral blood of patients with transitional cell carcinoma.

Uroplakins (UPs), urothelium-specific transmembrane proteins, are present only in urothelial cells. We have determined the nucleotide sequences of human UP-Ib and UP-III and synthesized specific primer pairs. The two UP genes were expressed in both cancerous and noncancerous urothelial taken from all patients examined by reverse transcription-polymerase chain reaction (RT-PCR). These genes were also detected in the peripheral blood of 3 patients with metastatic transitional cell carcinoma (TCC), but not in that from 9 patients with non-metastatic TCC or 3 healthy volunteers. The sensitivity of our assay was sufficient to detect one cancer cell in 5 ml of peripheral blood. Detection of UP gene-expression in blood by RT-PCR may provide helpful information for the diagnosis and management of TCC.

Adult↗
PubMed1998

Antitumor killer lymphocytes in the peripheral blood of a patient with transitional cell carcinoma of the bladder.

BACKGROUND: Peripheral blood lymphocytes (PBL) from patients with bladder cancer also contain cells possessing cytotoxic activity against autologous tumor cells. These cells are phenotypically heterogenous and include natural killer (NK) and cytotoxic T cells. This study investigated the role of cytotoxic lymphocytes directed against autologous bladder cancer cells. METHODS: PBL were obtained at intervals before and after surgery and analyzed for cytotoxic activity against autologous bladder cancer cells in 4-hour 51Cr release assay. PBL stimulated with autologous tumor cells were also transformed with human T-lymphotropic virus type-1, establishing a cell line (KB31) which was analyzed for phenotype and cytotoxic activity against the autologous tumor cells. RESULTS: PBL preoperative cytotoxic activity was low, but increased after surgery. Cytotoxic activity was found not only against autologous bladder cancer cells, but also against heterologous bladder cancer (KK-47) and myeloid leukemia (K562) cells, with the highest activity against the heterologous cell lines. The cytotoxic activity of KB31 was 40% against autologous tumor cells 6 weeks after initiation of the cell line, but decreased to 5% by 6 months. This activity was lower than that against the other cell lines, and was similar to that of PBL in short-term culture. Fluorescence-activated cell sorter (FACS) analysis demonstrated that in KB31 cells at 6 weeks, CD8+ cells were dominant, but CD56+ cells predominated at 6 months. CONCLUSION: These results suggest that the presence of cytotoxic activity in the peripheral blood of the patient was due to both cytotoxic T cells and NK cells. The cytotoxic activity was lowest prior to surgery and increased postoperatively.

Aged↗
PubMed1998

Electrophysiological features of central motor conduction in spinocerebellar atrophy type 1, type 2, and Machado-Joseph disease.

OBJECTIVES: To characterise electrophysiologically the central motor conduction of spinocerebellar atrophy type 1 (SCA1), type 2 (SCA2), and Machado-Joseph disease (MJD). METHODS: Motor evoked potentials (MEPs) triggered by transcranial magnetic stimulation (TMS) was used to investigate the functions of corticospinal tracts of 10 patients with SCA1, 10 with MJD, and eight with SCA2 in addition to pathological study of the spinal cord in a patient with SCA1. RESULTS: Central motor conduction time (CMCT) was extremely prolonged and the MEP threshold increased in all patients with SCA1, whereas both were normal in patients with SCA2 or MJD. The MEP size in MJD was larger than normal, but was normal in SCA1 and SCA2. A pathological investigation of the corticospinal tract of the spinal cord of a patient with SCA1 showed selective loss of large diameter fibres. CONCLUSIONS: SCA1, SCA2, and MJD differ in their pathophysiological features of the central motor tract and can be differentiated from each other by MEP values for the lower limb muscles, even though their neurological symptoms are sometimes similar.

Adult↗
PubMed1998

Spectral analysis of heart rate, arterial pressure, and muscle sympathetic nerve activity in normal humans.

We investigated the frequency components of fluctuations in heart rate, arterial pressure, respiration, and muscle sympathetic nerve activity (MSNA) in 11 healthy women using an autoregressive model and examined the relation among variables using Akaike's relative power contribution analysis with multivariate autoregressive model fitting. Power spectral analysis of MSNA revealed two peaks, with low-frequency (LF) and high-frequency (HF) components. The LF component of MSNA was a major determinant of the LF component of arterial pressure and R-R interval variability (0.70 +/- 0.07 and 0.18 +/- 0.05, respectively). The effect of the LF component of MSNA on arterial pressure showed no change in response to propranolol but was diminished (0.35 +/- 0.08) by phentolamine (P < 0.02). The effect of the LF component of MSNA on R-R interval was not altered by pharmacological sympathetic nerve blockade. The HF component of MSNA did not influence other variables but was influenced by R-R interval, arterial pressure, and respiration. These findings indicate that the LF component of MSNA reflects autonomic oscillations, whereas the HF component is passive and influenced by other cardiovascular variables.

Adolescent↗
PubMed1998

Bilateral coronary artery fistulas with multiple sites of drainage.

A 49-year-old woman presented with bilateral coronary fistulas with multiple sites of drainage. She had been referred to hospital for evaluation of a cardiac murmur, and a coronary arteriogram revealed multiple coronary fistulas. One fistula originated from the proximal part of the left anterior descending coronary artery and connected to the main pulmonary artery. Three coronary artery fistulas arised from a conal branch of the right coronary artery and drained into the main pulmonary artery, the right atrium and the great cardiac vein. This is the first reported case of bilateral coronary fistulas with multiple sites of drainage.

Coronary Angiography↗
PubMed1998

Germinoma causing wallerian degeneration. Case report and review of the literature.

Germinomas occurring in the thalamus and basal ganglia sometimes cause atrophy of the cerebral hemisphere on the affected side. The authors present the case of a 12-year-old girl with a germinoma that developed in the basal frontal lobe and cerebral basal ganglia. Magnetic resonance imaging showed atrophy not only of the cerebrum but also of the brainstem. A T2-weighted image revealed an area of high intensity that proved to be wallerian degeneration extending from the corona radiata and internal capsule to the brainstem. The authors suggest that this pathological change may be involved in the development of the symptoms and hemiatrophy associated with germinomas in this region of the brain.

Brain Neoplasms↗
PubMed1998

[A case report of epidural abscess due to anaerobic bacteria, producing a mass of gas].

A 54-year-old female was admitted to our hospital on May 8, 1996, for evaluation of fever and headache. Her cerebrospinal fluid showed elevation of the cell count and total protein. The thoracic and lumbar MRIs revealed abnormal gas occupying the epidural space at the sacral level, and extended as high as 9th thoracic level. The gas spread inside the iliopsoas and paraspinal muscles. Anaerobic bacteria such as Bacteroides fragilis and Peptostreptococcus productus were cultured from the spinal fluid and Bacteroides was also detected from the epidural tissues obtained during laminectomy. The infectious source was decubitus extending around the sacral bone. The combination therapy of debridement with peroxide, catheter drainage of epidural abscess, intravenous and intrathecal antibiotics, and laminectomy presented her good outcome. This is a rare case of anaerobic bacterial spinal abscess, showing epidural and intramuscular gas as a prominent feature.

Abscess↗
PubMed1997

Estrogen inhibits bone resorption by directly inducing apoptosis of the bone-resorbing osteoclasts.

Estrogen deficiency causes bone loss, which can be prevented by estrogen replacement therapy. Using a recently developed technique for isolation of highly purified mammalian osteoclasts, we showed that 17 beta-estradiol (E2) was able to directly inhibit osteoclastic bone resorption. At concentrations effective for inhibiting bone resorption, E2 also directly induced osteoclast apoptosis in a dose- and time-dependent manner. ICI164,384 and tamoxifen, as pure and partial antagonists, respectively, completely or partially blocked the effect of E2 on both inhibition of osteoclastic bone resorption and induction of osteoclast apoptosis. These data suggest that the protective effects of estrogen against postmenopausal osteoporosis are mediated in part by the direct induction of apoptosis of the bone-resorbing osteoclasts by an estrogen receptor- mediated mechanism.

Animals↗
PubMed1997

Severe cutaneous and venous damage after DIC therapy.

A 79-year-old woman with skin ulcers caused by disseminated intravascular coagulation (DIC) therapy is reported. The patient had been treated by injection of drugs, including gabexate mesilate, into the right great saphenous vein. The maximum concentration of gabexate mesilate was calculated as 0.893%. Although the drugs did not extravasate, purpura initially appeared around the affected vein, followed by brown pigmentation with infiltration and ulcers with widely necrotic tissue from the middle portion of her thigh to the malleolus along her right great saphenous vein. As the ulcer showed no tendency to heal for more than 3 months, surgical debridement and skin grafts were performed.

Aged↗
PubMed1997

Osteoclasts are present in gp130-deficient mice.

Interleukin (IL)-6, IL-11, leukemia inhibitory factor, and oncostatin M similarly induce osteoclast formation in cocultures of osteoblastic cells and bone marrow cells. These cytokines share a common signal transducer, gp130, which forms a receptor complex with the specific receptor for each cytokine. To investigate the role of gp130 in osteoclast development, we examined bone tissues in gp130-deficient and wild-type newborn mice of the ICR background. Soft x-ray radiographs and microfocus x-ray computed tomographs revealed that bone marrow cavities were present in tibiae and radii of both wild-type and gp130-deficient mice. Microfocus x-ray computed tomography and histological examination demonstrated a decrease in the amount of trabeculae at the metaphysial region in tibiae and radii of the gp130-deficient mice compared with the wild-type mice. The number ofosteoclasts in gp130-deficient mice was about double that in the wild-type mice. There were no apparent differences in the distributions of alkaline phosphatase-positive osteoblasts and the osteoid surface on the trabecular bone at the metaphysial region between the wild-type and gp130-deficient mice. The volume of mineralized trabecular bones was also decreased at mandibulae, accompanied by the increased number of osteoclasts in gp130-deficient mice compared with the wild-type and heterozygous mice. These results suggest that the formation of osteoclasts is not solely dependent on gp130 signaling, at least during fetal development. The osteoclastic bone resorption in gp130-deficient mice may be caused by the functional redundancy of bone-resorbing hormones and cytokines other than those of the IL-6 family.

Animals↗