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T Tsukada

Publications and source records attributed to T Tsukada.

At least 55 records · Page 3Linked to original sources
PubMed1998

Apoptosis induction in synovial fibroblasts by ceramide: in vitro and in vivo effects.

Several lipid second messengers are important mediators of extracellular signals. Among them ceramide, which is formed by cell membrane sphingomyelin, influences the apoptotic signal pathway through Fas antigen. We examined the apoptotic effect of cell-permeable C2-ceramide on rheumatoid synovial fibroblasts in vitro and in vivo. Exposure of cultured human rheumatoid synovial fibroblasts to C2-ceramide for 24 hours produced internucleosomal DNA fragmentation and morphologic changes characteristic of apoptosis. This C2-ceramide-mediated apoptosis was dose dependent as confirmed by analysis of cytosolic oligonucleosome-bound DNA of treated synovial fibroblasts. We also demonstrated that intra-articular administration of C2-ceramide into Fas-deficient MRL lpr/lpr mice produced a profound reduction of synovial hyperplasia within 24 hours. In situ nick end labeling analysis confirmed the induction of apoptosis in synovial lining cells. Our results indicate that C2-ceramide may function as a potent inducer of apoptosis in the synovium and suggest that pharmacologically-induced apoptosis may be useful as a new therapeutic modality for rheumatoid arthritis.

Animals↗
PubMed1998

Impact of presence of abnormal wall motion on echocardiographic determination of left ventricular function with automated boundary detection technique: re-evaluation.

It is still unclear whether echocardiography with an automated boundary detection technique (ABD) can accurately determine the left ventricular (LV) volume and function particularly in the presence of LV wall asynergy. We intended to re-evaluate the reliability and application of the ABD, which was based on the acoustic quantification technique (Sonos 2500, Hewlett Packard) for the LV volume measurement in patients without or with LV wall asynergy. A total of 80 patients (mean age 56 years) who underwent left ventriculography (LVG) were divided into two groups. The group A consisted of 29 patients with normal LV wall motion and the group B consisted of 51 patients with generalized or regional LV wall motion abnormality. In group A patients, the LV end-diastolic volume (LVEDV) was 96 +/- 25 ml by ABD and 112 +/- 33 ml by LVG and those of LV end-systolic volume (LVESV) were 44 +/- 14 ml by ABD and 48 +/- 17 ml by LVG, thus resulting in the underestimation of LV volume by 12% in average. Under these conditions, the LV ejection fraction (LVEF) by ABD, 54 +/- 8%, correlated well with that by LVG, 58 +/- 7%. Although underestimation of LV volume by 17% in average also occurred in groups B (N.S.), LVEF was found to correlate well with that by LVG; 27 +/- 8% vs 30 +/- 11% (r = 0.87, SEE = 3.1%) for 21 patients with the generalized LV asynergy; 39 +/- 10% vs 39 +/- 12% (r = 0.86. SEE = 3.3%) for 30 patients with the regional LV asynergy. These results demonstrate the feasibility of the ABD in determining the LVEF, although underestimation can occur in measuring the absolute LV volume in patients with or without LV asynergy.

Case-Control Studies↗
PubMed1998

Enhanced NOR-1 gene expression by exposure of Chinese hamster cells to high-density 50 Hz magnetic fields.

Enhanced expression of neuron derived orphan receptor (NOR-1) gene was observed by exposure of Chinese hamster ovary K1 (CHO-K1) cells to an extremely low frequency magnetic field (ELFMF) of 50 Hz at 400 mT, but not at 5 mT. The enhanced expression, reaching the maximum at 6 h, was transient and reduced to the control level after exposure to 400 mT ELFMF for 24 h. The NOR-1 expression induced by treatment with forskolin and TPA was further enhanced by the simultaneous treatment with 400 mT ELFMF, in which the maximum response was at 3 h. The NOR-1 expression by these treatments was induced more earlier than that by 400 mT ELFMF alone. When cells were treated with an inhibitor of the protein kinase C (calphostin C or crocetin) and Ca2+ entry blockers (nifedipin and dantrolen) during the 400 mT ELFMF exposure, the enhanced NOR-1 expression was not observed. Exposure of CHO-K1 cells to the high-density 400 mT ELFMF may affect the signal transduction in the cells, resulting in the enhanced NOR-1 gene expression.

Animals↗
PubMed1998

Apa I polymorphism in the vitamin D receptor gene may affect the parathyroid response in Japanese with end-stage renal disease.

Vitamin D [1,25(OH)2D3] plays a key role in the pathogenesis of secondary hyperparathyroidism. A polymorphism in the vitamin D receptor (VDR) gene is reported to be involved in bone mineral density and the serum level of intact-osteocalcin (i-OC) in patients with osteoporosis. We investigated the relationship between VDR gene polymorphisms and the levels of intact PTH (i-PTH) and i-OC in 129 Japanese patients with end-stage renal disease (ESRD). The VDR gene sequences were PCR-amplified, and the product was cleaved with the restriction enzymes Bsm I and Apa I. Undigested alleles were designated as B and A, and the digested alleles as b and a, respectively. The frequencies for the Bsm I polymorphism were 0.0% BB, 19.4% Bb, and 80.6% bb, while those for Apa I polymorphism were 14.2% AA, 47.2% Aa, and 38.6% aa. The Bsm I polymorphism of VDR was greatly biased in Japanese people. The i-PTH level in the aa group was about twice as high as those in the both AA group and Aa group (P < or = 0.04). The i-OC concentrations in the aa group was also approximately double those in both the AA group and Aa group (P < or = 0.03). In contrast, no significant differences in age, duration of dialysis, male/female ratio, or the incidence of diabetic nephropathy were observed among these three groups. On the other hand, there was no significant differences in i-PTH and i-OC between the Bb and bb groups. These results suggest that VDR gene polymorphisms can affect parathyroid response in ESRD patients, and the Apa I polymorphism is more informative in Japanese patients than the Bsm I polymorphism. The VDR a gene allele may define the pathogenesis of secondary hyperparathyroidism and of high turnover bone disease in patients with ESRD.

Alleles↗
PubMed1998

A large germline deletion of the MEN1 gene in a family with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is a familial cancer syndrome inherited as an autosomal dominant trait. Various heterozygous germline mutations of the responsible gene, MEN1, have been identified within its exons in many, but not all, affected individuals. We here demonstrate, by DNA polymorphism analysis and gene dosage analysis with polymerase chain reaction (PCR), a large heterozygous germline MEN1 deletion in a kindred with MEN1, in whom no mutation could be detected in the PCR-amplified exons. The deletion spanned an at least 7 kb region containing the entire MEN1 gene. These findings indicate that a large germline deletion of the MEN1 gene, which escapes detection in PCR-based sequence analysis, should be considered as a potential cause of MEN1.

Chromosome Deletion↗
PubMed1998

Comparison of automatic boundary detection and manual tracing technique in echocardiographic determination of left atrial volume.

Previous reports have indicated that echocardiography with automatic boundary detection (ABD) is useful for the noninvasive estimation of left ventricular volume. However, few data exist regarding the measurement of left atrial (LA) volume, which also provides pivotal information in the clinical setting. Therefore, the feasibility of LA volume measurement by ABD in comparison with the manual tracing using modified Simpson's method (SM) was evaluated. Fifty-nine patients with coronary artery-disease with sinus rhythm were examined. Using ABD, a region of interest was set around the LA border and mitral annulus from an apical four-chamber view. The maximal and minimal LA volume (Vmax and Vmin) were measured from the volume waveform. Using the SM, the maximal and minimal LA volume were measured by the manual tracing on frozen frames at the apical four-chamber view. The ABD displayed a curve of LA volume change that consisted of passive emptying, diastasis, and active emptying phases during the left ventricular diastolic period. Under these conditions, the Vmax and Vmin were 43.7 +/- 11.2 ml and 21.1 +/- 7.6 ml, respectively, yielding the volume change of 22.6 +/- 6.0 ml. By the SM, Vmax and Vmin were 43.1 +/- 9.9 ml (r = 0.94, p < 0.0001, y(ABD) = 0.91x (SM) + 3.6) and 22.0 +/- 9.0 ml (r = 0.91, p < 0.0001, y = 0.94x + 0.7), respectively, and the volume change was 22.8 +/- 6.1 ml (r = 0.82, p < 0.0001, y = 0.84x + 3.8). These results indicate that the ABD from the apical four-chamber approach could provide an accurate estimation of LA volume change, suggesting the potential value of this method in assessing LA function, although some technical difficulties need to be further overcome.

Adult↗
PubMed1998

The NGFI-B subfamily of the nuclear receptor superfamily (review).

NGFI-B, Nurr1 and NOR-1 have structural features of ligand-activated transcriptional regulators and constitute the NGFI-B subfamily within the nuclear receptor superfamily. Since specific ligands for these molecules have not yet been identified, they are often called orphan nuclear receptors. Genes of the NGFI-B subfamily are classified as immediate-early genes that are induced rapidly but transiently by a variety of stimuli. Evidence accumulated over the past decade suggests this subfamily is involved in important physiological processes and cancer development. In this communication, we summarize and discuss their structural features, gene expression, physiological roles and oncological significance.

Animals↗
PubMed1998

[Experience of weaning from left ventricular assist system in an acutely-ill patient with dilated cardiomyopathy and severe left ventricular dysfunction: a case report].

A 21-year-old man with dilated cardiomyopathy recovered from terminal heart failure with the long-term use of the left ventricular assist system (LVAS). His heart failure was refractory to maximum medical therapy including beta-blockade and intravenous catecholamines. Application of LVAS restored renal and hepatic function and even cardiac function. Left ventricular size decreased from 79 to 57 mm, and cardiac index increased from 1.6 to 2.2 l/min/m2. After 6 weeks of LVAS application, he could walk in the ward and could start exercise on a bicycle ergometer 3 months after. Ninety-five days after implantation, the LVAS could be removed. His general condition remained good and stable for more than a year after the removal of the LVAS. Timely application of LVAS seems to be one of the most important factors for successful circulatory support. Detailed criteria for LVAS application are not established yet.

Adult↗
PubMed1998

Effect of fluvastatin sodium on the smooth muscle cells in atherosclerotic plaques. In vivo study using low-density lipoprotein receptor deficient Watanabe heritable hyperlipidemic (WHHL) rabbits.

The effects of fluvastatin sodium (CAS 93957-55-2, XU 62-320), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on the smooth muscle cells in the atherosclerotic plaques of Watanabe heritable hyperlipidemic (WHHL) rabbits, a low density lipoprotein (LDL) receptor deficient animal model, were examined. Fluvastatin was administered to WHHL rabbits for 32 weeks at a dose of 50 mg/kg of body weight. The control WHHL rabbits were administered distilled water as placebo. Compared to the control group, the total cholesterol levels in the sera, very low density lipoprotein, intermediate density lipoprotein, and LDL decreased by 34%, 72%, 63%, and 25%, respectively. Although the surface lesion area of the aorta in the treated group was not different from that in the control group, intimal thickening in the treated group was significantly lower than that in the control group. Of the lesional components of atherosclerosis, the relative area of smooth muscle cells, collagen fibers, and extracellular lipid deposits in the treated group decreased significantly. It is concluded that fluvastatin decreased in the smooth muscle cell content of the atherosclerotic plaques and delayed progression of the aortic atherosclerosis in addition to the potent hyperlipidemic effect.

Animals↗
PubMed1997

Apoptosis induction in human peripheral blood T lymphocytes by high-dose steroid therapy.

High-dose steroid pulse therapy is effective in transplant rejection and severe autoimmune diseases. Our goal was to identify the mechanism by which high-dose steroid exerts specific immunosuppressive actions. In this study, we investigated the in vivo effects of high-dose (1 g) methylprednisolone infusion on peripheral blood T lymphocyte apoptosis induction in 15 patients with severe autoimmune diseases. DNA fragmentation was detected in peripheral blood T cells isolated from these patients after 2 and 4 hr of steroid infusion. In contrast, T cells isolated from the same patients before or 8 or more hours after infusion did not show DNA fragmentation. DNA fragmentation was more significant in CD4+ than CD8+ T cells. The susceptibility of CD4+ T cells to apoptosis was associated with a lower expression of Bcl-2 in these cells compared with that on CD8+ T cells. To support the T-cell apoptosis induction by pulse therapy, peripheral blood T cells from normal subjects underwent DNA fragmentation after in vitro exposure to 2.5-10 microg/ml of methylprednisolone for 30 min. Our results indicate that induction of peripheral blood T-cell apoptosis is an important mechanism contributing to the immunosuppression observed after high-dose steroid therapy.

Adult↗
PubMed1997

Retinoic acids differentially regulate NOR-1 and its closely related orphan nuclear receptor genes in breast cancer cell line MCF-7.

NOR-1, NGFI-B, and Nurr1 are closely related orphan nuclear receptors implicated in diverse biological processes including cell growth and differentiation. We examined the effect of retinoic acids on the expression of these putative transcription factor genes in the breast cancer cell line MCF-7 by a quantitative reverse transcription and polymerase chain reaction. Both all-trans and 9-cis retinoic acids markedly induced NOR-1 mRNA and slightly increased Nurr1 mRNA. In contrast, NGFI-B mRNA was decreased. In the presence of cycloheximide, all-trans retinoic acid superinduced NOR-1 mRNA, whereas all-trans and 9-cis retinoic acids strongly suppressed the NGFI-B mRNA accumulation. The differential effects of retinoic acids on the expression of these genes are in contrast with the effects of forskolin and 12-O-tetradecanoylphorbol-13-acetate, both of which induced mRNAs of all three genes. These findings suggest that NOR-1, NGFI-B, and Nurr1 play distinct roles in the retinoic acid signaling in MCF-7 cells.

Alitretinoin↗
PubMed1997

Superantigen-induced stromelysin production from rheumatoid synovial cells.

Superantigens activate a large number of T cells in a V beta-restricted manner after binding to MHC class II molecules on the antigen presenting cells (APC). Superantigens also activate APC directly by interacting with their ligands, MHC class II molecules. In the present study, we examined the effects of superantigens on matrix metalloproteinases (MMPs) secretion from rheumatoid synovial fibroblasts. We demonstrated that stimulation of interferon (IFN)-gamma-treated synovial fibroblasts with staphylococcal enterotoxin A (SEA) selectively induced the secretion of stromelysin, a neutral MMP, from synovial fibroblasts. Pretreatment of synovial fibroblasts with cycloheximide, an inhibitor of protein synthesis, prevented MMP-3 secretion from rheumatoid synovial cells suggesting that protein synthesis was required for SEA-induced MMP-3 secretion after SEA binding to MHC class II molecules. Our data suggest that in the synovium, bacterial superantigens are potent inducers of stromelysin which plays a critical role in articular destruction observed in inflammatory joint disease.

Arthritis, Rheumatoid↗
PubMed1997

Differentiation of cultured neuroblastoma induced by staurosporine and cyclic AMP: methods for assessing a neuronal phenotype.

In cultured neuronal cells, neurite outgrowth provides a prominent morphological marker for assessing neurotrophic activity derived from different sources. Permanent cell lines are often used for such studies; however, the process of differentiation should be evaluated biochemically or electrophysiologically to determine whether the affected cells acquire a neuronal phenotype. We have reported that low-dose staurosporine acts synergistically with cyclic AMP to induce neuronal differentiation in a human neuroblastoma cell line. This protocol describes a method for examining phenotypic changes in cultured cells.

Cell Differentiation↗