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Biomedical subjects

K Takeuchi

Publications and source records attributed to K Takeuchi.

At least 127 records · Page 7Linked to original sources
PubMed2001

Clinical significance of antibiotic therapy in guided tissue regeneration with a resorbable membrane.

This study was designed to evaluate the clinical significance of antibiotic therapy combined with guided tissue regeneration (GTR) therapy with a collagen membrane. The subjects were 20 adults diagnosed with periodontitis (20 intrabony periodontal defects). Ten patients were treated with GTR alone (control group) and the other 10 patients were treated with a combination of GTR and antibiotics (antibiotic group). In the antibiotic group, minocycline ointment was applied locally before GTR therapy, and doxycycline and amoxyline were systemically administered after GTR therapy. Clinical manifestations, the presence or absence of exposed membrane, and microbiological findings were assessed 1 month before, immediately after, and 2 weeks, 6 weeks, and 3 months after GTR therapy. The results showed no significant differences in reduction of probing depth, probing attachment gain (PAG), or the ratio of PAG to intraoperative depth of the intrabony defect (vertical relative attachment gain) between the antibiotic group and the control group before and 3 months after GTR therapy. A DNA probe test and specific enzymatic activity test revealed no significant differences in the improvement and the rate of bacterial negativity before, and 6 weeks and 3 months after, GTR therapy. These findings indicate that antibiotic therapy is not clinically beneficial when combined with GTR therapy with a collagen membrane.

Absorbable Implants↗
PubMed2001

[Therapeutic plasmapheresis for the prevention of congenital complete heart block associated with anti-SS-A/Ro antibody and anti-SS-B/La antibody].

OBJECTIVES: Neonatal lupus erythematosus is characterized by transient lupus abnormalities, various systemic and hematological abnormalities, and congenital complete heart block (CCHB). It is well known that anti-SS-A/Ro antibody (52 kD/60 kD) and anti-SS-B/La antibody are associated with CCHB. This study was conducted to evaluate the effects of the removal of anti-SS-A/Ro antibody (52 kD/60 kD) and anti-SS-B/La antibody from plasma in pregnant women whose fetuses are at a high risk of developing CCHB. MATERIALS & METHODS: Fifteen pregnant patients positive for anti-SS-A/Ro antibody and anti-SS-B/Laantibody were subjected weekly to double filtration plasmapheresis to remove both antibodies. Antibody titers were measured by double immunodiffusion (DID) and ELISA. RESULTS: As a result, all women gave birth to live babies, but CCHB was recognized in one baby. No transient lupus abnormalities were recognized in any of the babies. Fourteen patients showed decreased antibody titers by ELISA during plasmapheresis. However, the patient who was delivered of a baby with CCHB showed an increase of antibody titers by ELISA while the DID method showed a decrease of antibody titers. CONCLUSION: Our study suggested that plasmapheresis prevents CCHB associated with anti-SS-A/Ro and anti-SS-B/La antibody. Also, it is important to monitor the antibody titer regularly during the course of pregnancy, because it may increase due to worsening of the mother's primary disease.

Adult↗
PubMed2001

[A high aged case of herpes simplex viral encephalitis associated with progressive cerebral white matter lesion].

An 80-year-old male without abnormal past medical history presented with coma, general seizures, and fever subsequent to abnormal behavior. The pressure of the cerebrospinal fluid(CSF) elevated(13.5-20.5 cm H2O), and CSF examination revealed pleocytosis with predominant mononuclear cells(80-879/mm3) and elevated protein level(32-130 mg/dl). DNAs of herpes simplex virus(HSV) type 1 and 2 in CSF were not confirmed by polymerase chain reaction method in the acute phase. The HSV(type 1) antibody(HSV-1 Ab) ratio of serum to CSF(= [serum HSV-1 Ab]/[CSF HSV-1 Ab]) was 0.98 and HSV-1 Ab index(= [CSF HSV-1 Ab]/[serum HSV-1 Ab] divided by [CSF albumin]/[serum albumin]) was 62.4. Initial fluid attenuated inversion recovery(FLAIR) (TR/TE/TI = 6,882/110/1,700 msec) axial magnetic resonance(MR) imaging showed hyperintensity in the subfrontal area, inferomedial portions of the temporal lobes, cingulate gyri, and insular cortices bilaterally. Meningoencephalitis caused by HSV-1 was diagnosed based on the values of HSV-1 Ab ratio of serum to CSF(less than 20), of HSV-1 Ab index(larger than 1.91), and the findings of MR imaging. Diffuse white matter lesions manifesting hyperintensity on FLAIR imaging in the bilateral frontal and temporal lobes close to the affected cortices developed approximately six weeks after the onset despite administration of antiviral agent and steroid. The lesion extensively involved the white matter of the bilateral frontal and temporal lobes finally. The initial value of myelin basic protein(MBP) in CSF was 0.9 ng/ml (normal value: less than 4 ng/ml). Subsequent measurement of MBP in CSF about two, six weeks, two, three, and six months after the onset showed a marked increase of 233.9 ng/ml followed by a gradual decrease of 25.4 ng/ml, 18.4 ng/ml, 7.4 ng/ml and 4.3 ng/ml, respectively. Therefore, demyelination of the lesion in the cerebral white matter was suggested by the chronological change in FLAIR imaging and MBP in CSF.

Aged↗
PubMed2001

[A case of bronchogenic cyst which developed from negative findings to a thin-walled cavity for about 6 years].

A 56-year-old man whose chest radiograph in 1993 was normal was referred to our hospital because of a productive cough in 1997. Chest radiographs showed a thin-walled cavity filled with air. We followed his condition radiographically for three years and observed enlargement of the diameter of the lesion and appearance of an air fluid level, and we therefore decided to perform thoracoscopic middle lobe resection in 1999. Histological examination showed a communication between the cavity and a bronchus. As far as we know, there are no previous reports about intrapulmonary bronchogenic cysts which on radiographic observation developed from negative findings to a thin-walled cavity filled with air over a 6-year period.

Bronchogenic Cyst↗
PubMed2001

[Spinal cord sarcoidosis without abnormal shadows on chest radiography or chest CT diagnosed by transbronchial lung biopsy].

The patient was a woman aged 56 years. In February 1998, she complained of fatigability of the right upper limb and disturbed extension of the right fourth finger. Because her condition deteriorated gradually and myelopathic signs such as difficulty in walking developed, she was hospitalized in May 1999 for close examination and appropriate treatment; and she was a few days later transferred to our hospital because of progressive myelopathy. In T2-weighted MR images of the cervical spine, the high-intensity area ranged between C2 and Th1, and in Gd-DTPA enhanced MRI the high-intensity area was seen between C3 and C7. Although chest radiographs and chest CT scans were normal, spinal cord sarcoidosis could not be ruled out, and therefore, bronchoscopic examination was performed. Specimens obtained from transbronchial lung biopsy (TBLB) revealed non-caseating epithelioid cell granulomas, and so and the disease was diagnosed as spinal cord sarcoidosis. Both symptoms and MRI findings were improved by treatment with corticosteroids. It is suggested that, in patients suspected of spinal cord sarcoidosis from MRI findings. TBLB should be aggressively attempted, even if chest radiographs and chest CT scans are normal.

Biopsy↗
PubMed2000

Myosin light-chain kinase regulates endothelial calcium entry and endothelium-dependent vasodilation.

Activation of smooth muscle myosin light-chain kinase (MLCK) causes contraction. Here we have proven that MLCK controls Ca2+ entry (CE) in endothelial cells (ECs): MLCK antisense oligonucleotides strongly prevented bradykinin (BK)- and thapsigargin (TG)-induced endothelial Ca2+ response, while MLCK sense did not. We also show that the relevant mechanism is not phosphorylation of myosin light-chain (MLC): MLC phosphorylation by BK required CE, but MLC phosphorylation caused by the phosphatase inhibitor calyculin A did not trigger Ca2+ response. Most important, we provide for the first time strong evidence that, in contrast to its role in smooth muscle cells, activation of MLCK in ECs stimulates the production of important endothelium-derived vascular relaxing factors: MLCK antisense and MLCK inhibitors abolished BK- and TG-induced nitric oxide production, and MLCK inhibitors substantially inhibited acetylcholine-stimulated hyperpolarization of smooth muscle cell membrane in rat mesenteric artery. These results indicate that MLCK controls endothelial CE, but not through MLC phosphorylation, and unveils a hitherto unknown physiological function of the enzyme: vasodilation through its action in endothelial cells. The study discovers a counter-balancing role of MLCK in the regulation of vascular tone.

Acetylcholine↗
PubMed2000

Nadrin, a novel neuron-specific GTPase-activating protein involved in regulated exocytosis.

It has been proposed that the cortical actin filament networks act as a cortical barrier that must be reorganized to enable docking and fusion of the synaptic vesicles with the plasma membranes. We identified a novel neuron-associated developmentally regulated protein, designated as Nadrin. Expression of Nadrin is restricted to neurons and correlates well with the differentiation of neurons. Nadrin has a unique structure; it contains a GTPase-activating protein (GAP) domain for Rho family GTPases, a potential coiled-coil domain, and a succession of 29 glutamines. In vitro the GAP domain activates RhoA, Rac1, and Cdc42 GTPases. Expression of Nadrin in NIH3T3 cells markedly reduced the number of the actin stress fibers and the formation of the ruffled membranes, suggesting that Nadrin regulates actin filament reorganization. In PC12 cells, Nadrin colocalized with synaptotagmin in the neurite termini and also with cortical actin filaments in the subplasmalemmal regions. Expression of Nadrin or its mutant composed of the coiled-coil and GAP domain enhanced Ca(2+)-dependent exocytosis of PC12 cells, but a mutant lacking the GAP domain inhibited exocytosis. These results suggest that Nadrin plays a role in regulating Ca(2+)-dependent exocytosis, most likely by catalyzing GTPase activity of Rho family proteins and by inducing the reorganization of the cortical actin filaments.

Actins↗
PubMed2000

Vesnarinone restores contractility and calcium handling in early endotoxemia.

BACKGROUND: Endotoxin (lipopolysaccharide, LPS) is a trigger of the systemic inflammatory response. We have previously found that vesnarinone and amrinone, when given before LPS, prevented cytokine production and LPS-related cardiac dysfunction. We tested the hypothesis that vesnarinone would improve intracellular Ca(2+) handling and calcium-activated contractile force after the onset of endotoxemia. METHODS AND RESULTS: Adult rabbits received a bolus injection of LPS or vehicle. Vesnarinone (3 mg/kg) was given intravenously 90 minutes later. Two hours after LPS administration, hearts were perfused in the isolated Langendorff mode. Peak left ventricular developed pressure, +/-dp/dt, oxygen consumption (MVO(2)), and ratexpressure product were evaluated in conjunction with fluorescent spectroscopic determinations of intracellular calcium concentrations (Ca(i)) and the rate of Ca(i) transient decline during diastole (tauCa). Peak left ventricular developed pressure and +/-dp/dt were significantly lower in the LPS group. These were completely restored by vesnarinone. There was significantly slower diastolic calcium removal (increased tauCa) in LPS hearts that was also corrected by vesnarinone; however, the cytosolic calcium overload characteristic of LPS hearts was only partially improved. Reduced mechanical inefficiency (the ratio of rate-pressure product to MVO(2)) and myofilament sensitivity to Ca(i) were also significantly improved by vesnarinone. CONCLUSIONS: Acute endotoxemia caused contractile protein calcium insensitivity, oxygen wastage, and abnormal calcium cycling. Vesnarinone, given in the rescue mode, normalized LPS-induced myocardial dysfunction and partially restored abnormal calcium cycling. Although the mechanisms responsible for these effects require further clarification, it appears that agents such as vesnarinone may be useful to treat inflammatory-induced myocardial dysfunction.

Animals↗
PubMed2000

Involvement of gangliosides in glycosylphosphatidylinositol-anchored neuronal cell adhesion molecule TAG-1 signaling in lipid rafts.

The association of ganglioside GD3 with TAG-1, a glycosylphosphatidylinositol-anchored neuronal cell adhesion molecule, was examined by coimmunoprecipitation experiments. Previously, we have shown that the anti-ganglioside GD3 antibody (R24) immunoprecipitated the Src family kinase Lyn from the rat cerebellum, and R24 treatment of primary cerebellar cultures induced Lyn activation and rapid tyrosine phosphorylation of an 80-kDa protein (p80). We now report that R24 coimmunoprecipitates a 135-kDa protein (p135) from primary cerebellar cultures. Treatment with phosphatidylinositol-specific phospholipase C revealed that p135 was glycosylphosphatidylinositol-anchored to the membrane. It was identified as TAG-1 by sequential immunoprecipitation with an anti-TAG-1 antibody. Antibody-mediated cross-linking of TAG-1 induced Lyn activation and rapid tyrosine phosphorylation of p80. Selective inhibitor for Src family kinases reduced the tyrosine phosphorylation of p80. Sucrose density gradient analysis revealed that the TAG-1 and tyrosine-phosphorylated p80 in cerebellar cultures were present in the lipid raft fraction. These data show that TAG-1 transduces signals via Lyn to p80 in the lipid rafts of the cerebellum. Furthermore, degradation of cell-surface glycosphingolipids by endoglycoceramidase induced an alteration of TAG-1 distribution on an OptiPrep gradient and reduced the TAG-1-mediated Lyn activation and tyrosine phosphorylation of p80. These observations suggest that glycosphingolipids are involved in TAG-1-mediated signaling in lipid rafts.

Animals↗
PubMed2000

Prognostic significance of CD56 expression for ALK-positive and ALK-negative anaplastic large-cell lymphoma of T/null cell phenotype.

Anaplastic large cell lymphoma (ALCL) is a distinct entity of non-Hodgkin lymphoma, characterized by a proliferation of pleomorphic large lymphoid cells that express CD30. Recent studies have found that a subset of ALCL aberrantly expresses a chimeric anaplastic lymphoma kinase (ALK) protein as a result of t(2;5)(p23;q35) or variant translocations. ALK-positive ALCLs feature good prognosis, but some of them lead to poor outcomes. Since CD56 is expressed in some ALCLs, its clinical significance was examined in a series of T/null cell type ALCLs. Of 143 patients, 83 (58%) showed ALK-positive staining, and of 140 patients, 25 (18%) expressed CD56. The ALK-positive subgroup was characterized by a younger age of onset (P <.0001), lower serum lactate dehydrogenase level (P =.01), better performance status (P =.03), less frequent extranodal involvement (P =.01), lower international prognostic index (IPI) categories (P =.002), and superior survival (P =.0009) in comparison with the ALK-negative group, suggesting that ALK is a specific marker defining a distinct subtype. CD56(+) cases showed a significantly poor prognosis overall (P =.002) as well as in both ALK-positive and ALK-negative subgroups (P =.02 and P =.04, respectively). Multivariate analysis confirmed that CD56 is independent of other prognostic factors, including IPI. Although CD56(+) cases showed a higher incidence of bone involvement, no other differences in clinicopathologic parameters were found between the CD56(+) and CD56(-) groups. These findings suggest that CD56 is not a marker to identify a distinct subtype of ALCL, but a strong clinical prognostic factor. Effective therapeutic approaches should be explored for high-risk ALCL patients, who can be identified by means of a prognostic model, including CD56.

Adolescent↗
PubMed2000

Mutations of the AML1 gene in myelodysplastic syndrome and their functional implications in leukemogenesis.

The AML1 gene encodes a DNA-binding protein that contains the runt domain and is the most frequent target of translocations associated with human leukemias. Here, point mutations of the AML1 gene, V105ter (single-letter amino acid code) and R139G, (single-letter amino acid codes) were identified in 2 cases of myelodysplastic syndrome (MDS) by means of the reverse transcriptase-polymerase chain reaction single-strand conformation polymorphism method. Both mutations are present in the region encoding the runt domain of AML1 and cause loss of the DNA-binding ability of the resultant products. Of these mutants, V105ter has also lost the ability to heterodimerize with polyomavirus enhancer binding protein 2/core binding factor beta (PEBP2beta/CBFbeta). On the other hand, the R139G mutant acts as a dominant negative inhibitor by competing with wild-type AML1 for interaction with PEBP2beta/CBFbeta. This study is the first report that describes mutations of AML1 in patients with MDS and the mechanism whereby the mutant acts as a dominant negative inhibitor of wild-type AML1.

Amino Acid Substitution↗
PubMed2000

Suppression of rat thromboxane synthase gene transcription by peroxisome proliferator-activated receptor gamma in macrophages via an interaction with NRF2.

We have studied the transcription regulation of the rat thromboxane synthase (TXS) gene by peroxisome proliferator-activated receptor gamma (PPARgamma) in macrophages. The transcription activity of a cloned 5'-flanking region (1.6 kilobases) of the rat TXS gene (5'FL-TXS) was examined by luciferase reporter gene assay. TXS mRNA expression and the transcription activity of 5'FL-TXS were inhibited by PPARgamma ligands, 15-deoxy-Delta(12,14)-prostaglandin J(2) (PGJ(2)), and the thiazolidinedione troglitazone (TRO) in a dose-dependent manner. Overexpression of PPARgamma also significantly suppressed transcription, and further addition of PGJ(2) or TRO augmented the suppression. Deletion analysis showed that the element responsible for the PPARgamma effect is located in a region containing the nuclear factor E2 (NF-E2)/AP-1 site (-98/-88), which was indicated to be the major promoter of the TXS gene. By electrophoretic mobility shift assay using the NF-E2/AP-1 site and nuclear extracts from macrophages, we observed a specific protein-DNA complex formation, which was inhibited by a specific antibody against the transcription factor NRF2 (NF-E2-related factor 2). Moreover, the complex was decreased with PGJ(2), TRO, or in vitro translated PPARgamma. The transcription suppression by PPARgamma was confirmed using this truncated NRF2-binding element (-98/-88) by the reporter gene assay. Finally, a direct interaction between PPARgamma and NRF2 was confirmed by glutathione S-transferase pull-down assay. In conclusion, the NRF2-binding site (-98/-88) is the major promoter of 5'FL-TXS which can be suppressed by activated PPARgamma via a protein-protein interaction with NRF2 in macrophages.

Animals↗
PubMed2000

Arsenite induces apoptosis of murine T lymphocytes through membrane raft-linked signaling for activation of c-Jun amino-terminal kinase.

Because of its dual roles in acute toxicity and in therapeutic application in cancer treatment, arsenic has recently attracted a renewed attention. In this study, we report NaAsO(2)-induced signal cascades from the cell surface to the nucleus of murine thymic T lymphocytes that involve membrane rafts as an initial signal transducer. NaAsO(2) induced apoptosis through fragmentation of DNA, activation of caspase, and reciprocal regulation of Bcl-2/Bax with the concomitant reduction of membrane potential. We demonstrated that NaAsO(2)-induced caspase activation is dependent on curcumin-sensitive c-Jun amino-terminal kinase and barely dependent on SB203580-sensitive p38 kinase or PD98059-sensitive extracellular signal-regulated kinase. Additionally, staurosporine, which severely inhibited the activation of mitogen-activated protein (MAP) family kinases and c-Jun, partially blocked the NaAsO(2)-mediated signal for poly(ADP-ribose) polymerase (PARP) degradation. Potentially as the initial cell surface event for intracellular signaling, NaAsO(2) induced aggregation of GPI-anchored protein Thy-1 and superoxide production. This Thy-1 aggregation and subsequent activation of MAP family kinase and c-Jun and the degradation of PARP induced by NaAsO(2) were all inhibited by DTT, suggesting the requirement of interaction between arsenic and protein sulfhydryl groups for those effects. beta cyclodextrin, which sequestrates cholesterol from the membrane rafts, inhibited NaAsO(2)-induced activation of protein tyrosine kinases and MAP family kinases, degradation of PARP, and production of superoxide. In addition, beta cyclodextrin dispersed NaAsO(2)-induced Thy-1 clustering. These results suggest that a membrane raft integrity-dependent cell surface event is a prerequisite for NaAsO(2)-induced protein tyrosine kinase/c-Jun amino-terminal kinase activation, superoxide production, and downstream caspase activation.

Animals↗
PubMed2000

Midkine inhibits bradykinin-stimulated Ca(2+) signaling and nitric oxide production in endothelial cells.

Effects of the heparin-binding growth factor midkine (MK) were investigated on endothelial Ca(2+) signaling and nitric oxide (NO) production. Bradykinin (10 nM) and thapsigargin (1 microM) provoked large Ca(2+) influxes under fura-2/AM fluoroscopy. Pretreatment with human MK dose-dependently (1-500 ng/ml) inhibited the Ca(2+) response to bradykinin but not that to thapsigargin. Anti-MK antibody prevented this effect. In Ca(2+)-free medium, MK greatly inhibited intracellular Ca(2+) store release by bradykinin and not that by thapsigargin, which effect was prevented by the antibody. Bradykinin increased NO production by 6.7-fold, which was inhibited 6, 44, 79, and 90% by MK at 1, 10, 100, and 500 ng/ml, respectively. MK did not affect thapsigargin-induced NO production. Our data clearly indicate that MK inhibits bradykinin-induced Ca(2+) response and NO production from endothelial cells.

Animals↗
PubMed2000

Acid-catalyzed rearrangement of ethynylcycloheptatriene to phenylallene.

7-Ethynylcycloheptatriene (1) cleanly isomerizes to phenylallene in the presence of acid. A mechanism involving the protonation of ethynylnorcaradiene, which is in equilibrium with 1, followed by the cleavage of a three-membered ring to give an arenium ion, is proposed. The rearrangement is accelerated by a factor of 370 by introducing tert-butyl groups on C-2 and C-5, indicating the importance of the equilibrium concentration of the norcaradiene form as a rate-controlling factor.

Journal Article↗
PubMed2000

Corticosteroid-responsive diabetes mellitus associated with autoimmune pancreatitis.

Autoimmune pancreatitis, which can be treated with corticosteroid therapy, has the potential to induce diabetes. In a cohort study of 2220 patients with suspected chronic pancreatitis, we found that all four patients with autoimmune chronic pancreatitis also had diabetes. Treatment with prednisolone subsequently improved insulin secretion and glycaemic control in these patients.

Aged↗