Biomedical subjects

T Kawai

Publications and source records attributed to T Kawai.

At least 145 records · Page 8Linked to original sources

PubMed1999

Death-associated protein kinase 2 is a new calcium/calmodulin-dependent protein kinase that signals apoptosis through its catalytic activity.

We have identified and characterized a new calcium/calmodulin (Ca2+/CaM) dependent protein kinase termed death-associated protein kinase 2 (DAPK2) that contains an N-terminal protein kinase domain followed by a conserved CaM-binding domain with significant homologies to those of DAP kinase, a protein kinase involved in apoptosis. DAPK2 mRNA is expressed abundantly in heart, lung and skeletal muscle. The mapping results indicated that DAPK2 is located in the central region of mouse chromosome 9. In vitro kinase assay revealed that DAPK2 is autophosphorylated and phosphorylates myosin light chain (MLC) as an exogenous substrate. DAPK2 binds directly to CaM and is activated in a Ca2+/CaM-dependent manner. A constitutively active DAPK2 mutant is generated by removal of the CaM-binding domain (deltaCaM). Treatment of agonists that elevate intracellular Ca2+-concentration led to the activation of DAPK2 and transfection studies revealed that DAPK2 is localized in the cytoplasm. Overexpression of DAPK2, but not the kinase negative mutant, significantly induced the morphological changes characteristic of apoptosis. These results indicate that DAPK2 is an additional member of DAP kinase family involved in apoptotic signaling.

3T3 Cells↗

PubMed1999

Molecular cloning of a novel human collectin from liver (CL-L1).

Collectins are a C-lectin family with collagen-like sequences and carbohydrate recognition domains. These proteins can bind to carbohydrate antigens of microorganisms and inhibit their infection by direct neutralization and agglutination, the activation of complement through the lectin pathway, and opsonization by collectin receptors. Here we report the cloning of a cDNA encoding human collectin from liver (CL-L1 (collectin liver 1)) that has typical collectin structural characteristics, consisting of an N-terminal cysteine-rich domain, a collagen-like domain, a neck domain, and a carbohydrate recognition domain. The cDNA has an insert of 831 base pairs coding for a protein of 277 amino acid residues. The deduced amino acid sequence shows that this collectin has a unique repeat of four lysine residues in its C-terminal area. Northern blot, Western blot, and reverse transcription-polymerase chain reaction analyses showed that CL-L1 is present mainly in liver as a cytosolic protein and at low levels in placenta. More sensitive analyses by reverse transcription-polymerase chain reactions showed that most tissues (except skeletal muscle) have CL-L1 mRNA. Zoo-blot analysis indicated that CL-L1 is limited to mammals and birds. A chromosomal localization study indicated that the CL-L1 gene localizes to chromosome 8q23-q24.1, different from chromosome 10 of other human collectin genes. Expression studies of fusion proteins lacking the collagen and N-terminal domains produced in Escherichia coli affirmed that CL-L1 binds mannose weakly. CL-L1 and recombinant CL-L1 fusion proteins do not bind to mannan columns. Analysis of the phylogenetic tree of CL-L1 and other collectins indicated that CL-L1 belongs to a fourth subfamily of collectins following the mannan-binding protein, surfactant protein A, and surfactant protein D subfamilies including bovine conglutinin and collectin-43 (CL-43). These findings indicate that CL-L1 may be involved in different biological functions.

Amino Acid Sequence↗

PubMed1999

Cutting edge: generation of IL-18 receptor-deficient mice: evidence for IL-1 receptor-related protein as an essential IL-18 binding receptor.

IL-18 is a proinflammatory cytokine that plays an important role in NK cell activation and Th1 cell response. Recently IL-1R-related protein (IL-1Rrp) has been cloned as the receptor for IL-18. However, the functional role of IL-1Rrp is still controversial due to its low affinity to IL-18 as well as the possibility of the presence of another high-affinity binding receptor. In the present study, we have generated and characterized IL-1Rrp-deficient mice. The binding of murine rIL-18 was not detected in Th1-developing splenic CD4+ T cells isolated from IL-1Rrp-deficient mice. The activation of NF-kappa B or c-Jun N-terminal kinase were also not observed in the Th1 cells. NK cells from IL-1Rrp-deficient mice had defects in cytolytic activity and IFN-gamma production in response to IL-18. Th1 cell development was also impaired in IL-1Rrp-deficient mice. These data demonstrate that IL-1Rrp is a ligand-binding receptor that is essential for IL-18-mediated signaling events.

Animals↗

PubMed1999

TLR6: A novel member of an expanding toll-like receptor family.

Drosophila Toll protein is shown to activate the innate immune system in adult and regulate the dorsoventral patterning in the developing embryo. Recently, five human homologs of Drosophila Toll, designated as Toll-like receptors (TLRs), have been identified and shown to play a role in the innate immune response. We report here the molecular cloning and characterization of a new member of Toll-like receptor family, Toll-like receptor 6 (TLR6). Human and murine TLR6 are type-I transmembrane receptors that contain both an extracellular leucine-rich repeat (LRR) domain and a cytoplasmic Toll/IL-1 receptor (IL-1R)-like region. The amino acid sequence of human TLR6 (hTLR6) is most similar to that of hTLR1 with 69% identity. RT-PCR analysis revealed that murine TLR6 is expressed predominantly in spleen, thymus, ovary and lung. Like other TLR family members, constitutively active TLR6 activates both NF-kappaB and c-Jun N-terminal kinase (JNK). The TLR6 gene, as well as the TLR1 gene, mapped to the proximal region of murine chromosome 5 within 1.7cM of each other. These results suggest that TLR6 is a novel member of an expanding TLR family.

3T3 Cells↗

PubMed1999

A Study on the Surface Silanol Groups Developed by Hydrothermal and Acid Treatment of Faujasite Type Zeolites.

The surface silanol groups on faujasite type zeolites, which were formed by hydrothermal and acid treatments and considered to be lattice defect, were characterized. IR measurements of silanol groups were made in situ and thermogravimetic analysis was conducted under vacuum so as to quantify their content. It was thus possible to quantify separately the concentration of silanol groups forming hydroxy nests and the concentration of terminal silanol groups present on the secondary pores and crystal external surfaces. As the evacuation temperature increased, silanol groups forming hydroxy nests were found to decrease as a result of dehydroxylation condensation. The number of terminal silanol groups on the secondary pores and external surface remained virtually unchanged. The concentration of terminal silanol groups agreed well with the value calculated according to the proposed destruction model of the zeolite framework. This justified the model that there remained the double 6-ring structure on the secondary pore surfaces after the sodalite cage was collapsed as a result of the treatments. The effect of silanol groups forming hydroxy nests on the zeolite surface polarity was examined by measuring immersional heats in various solvents. It turned out that the extremely localized silanol groups forming hydroxy nests in the framework were linked via hydrogen bond to each other and showed nonpolar behavior. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Limb and skin abnormalities in mice lacking IKKalpha.

The gene encoding inhibitor of kappa B (IkappaB) kinase alpha (IKKalpha; also called IKK1) was disrupted by gene targeting. IKKalpha-deficient mice died perinatally. In IKKalpha-deficient fetuses, limb outgrowth was severely impaired despite unaffected skeletal development. The epidermal cells in IKKalpha-deficient fetuses were highly proliferative with dysregulated epidermal differentiation. In the basal layer, degradation of IkappaB and nuclear localization of nuclear factor kappa B (NF-kappaB) were not observed. Thus, IKKalpha is essential for NF-kappaB activation in the limb and skin during embryogenesis. In contrast, there was no impairment of NF-kappaB activation induced by either interleukin-1 or tumor necrosis factor-alpha in IKKalpha-deficient embryonic fibroblasts and thymocytes, indicating that IKKalpha is not essential for cytokine-induced activation of NF-kappaB.

Animals↗

PubMed1999

Cutting edge: Toll-like receptor 4 (TLR4)-deficient mice are hyporesponsive to lipopolysaccharide: evidence for TLR4 as the Lps gene product.

The human homologue of Drosophila Toll (hToll), also called Toll-like receptor 4 (TLR4), is a recently cloned receptor of the IL-1/Toll receptor family. Interestingly, the TLR4 gene has been localized to the same region to which the Lps locus (endotoxin unresponsive gene locus) is mapped. To examine the role of TLR4 in LPS responsiveness, we have generated mice lacking TLR4. Macrophages and B cells from TLR4-deficient mice did not respond to LPS. All these manifestations were quite similar to those of LPS-hyporesponsive C3H/HeJ mice. Furthermore, C3H/HeJ mice have, in the cytoplasmic portion of TLR4, a single point mutation of the amino acid that is highly conserved among the IL-1/Toll receptor family. Overexpression of wild-type TLR4 but not the mutant TLR4 from C3H/HeJ mice activated NF-kappaB. Taken together, the present study demonstrates that TLR4 is the gene product that regulates LPS response.

Amino Acid Sequence↗

PubMed1999

Duet is a novel serine/threonine kinase with Dbl-Homology (DH) and Pleckstrin-Homology (PH) domains.

We show here the identification of Duet, a novel molecule bearing serine/threonine kinase, Dbl-Homology (DH), and Pleckstrin-Homology (PH) domains. The kinase domain of Duet shows a homology to that of DAP kinase that is involved in apoptosis, and Duet is autophosphorylated by an in-vitro kinase assay. The DH- and PH-domains are closely related to those of Trio and Kalirin. Trad mRNA is specifically expressed in skeletal muscle. Duet protein was localized to actin-associated cytoskeletal elements. These data suggest a role of Duet in the cytoskeleton-dependent cell function.

3T3 Cells↗

PubMed1999

High-level and effective production of human mannan-binding lectin (MBL) in Chinese hamster ovary (CHO) cells.

We have developed a high-expression system of recombinant human mannan-binding lectin (MBL) with CHO cells. Geneticin-resistant transformants harboring human MBL cDNA in the expression vector pNOW/CMV-A were screened by immunoblot analysis for secretion of recombinant MBL. Cloning and selection by both geneticin and methotrexate resulted in the production of recombinant MBL to a final concentration of 128.8 microg/ml in media after four days of culture. SDS-PAGE and gel-filtration analyses showed that recombinant MBL is characterized by two lower-order oligomeric structures (apparent molecular weights: 1150 kDa and 300 kDa) compared to native MBL (apparent molecular weight: 1300 kDa). The recombinant human MBL has both sugar-binding and complement activation activity and, like native MBL, can inhibit hemagglutination of influenza A virus. Lectin blots with recombinant MBL indicate that it can bind such microorganisms as HIV and influenza virus suggesting that it might inhibit their infection of hosts. This high-level expression of human MBL with the full range of biological activity will be useful for studies on the immunological role of MBL in humans.

Animals↗

PubMed1999

Evaluation of coronary artery bypass grafts using helical scan computed tomography.

The patency of coronary artery bypass grafts was evaluated by helical computed tomographic (CT) scan. One hundred forty patients who received an enhanced chest CT scan and a coronary angiography after bypass surgery were studied before discharge at the Fukui Cardiovascular Center. Among them was a total of 398 grafts and 436 anastomoses. For the evaluation of 248 vein grafts, the CT scan showed a 99.5% correct positive ratio and an overall accuracy of 96.4%. In 122 internal thoracic arteries tested, an overall accuracy of 64.7% was obtained. In gastroepiploic artery tests the overall accuracy was 33.3% and in radial artery tests it was 45.5%. Thirty-seven venous sequential anastomoses in 34 grafts and 1 internal thoracic artery sequential anastomosis were also evaluated. In the venous sequential anastomosis, the CT scan showed a 73.0% of accuracy overall. This study showed that the helical CT scan was useful to evaluate graft patency following bypass surgery.

Adolescent↗

PubMed1999

Serum levels of Clara cell 10-kDa protein are decreased in patients with asthma.

Clara cell 10-kDa protein (CC10), the predominant product from nonciliated cells in the epithelial lining of bronchioles (Clara cells), has been shown to have immunomodulatory and antiinflammatory activity and may play a role in controlling airway inflammation. This study was designed to measure serum CC10 concentrations in healthy and asthmatic nonsmokers. Serum CC10 concentrations in asthmatic nonsmokers were significantly lower than in healthy nonsmokers. Asthmatic patients with a long duration of the disease (>/=10 years) had significantly lower serum CC10 levels than those with a short duration of the disease (<10 years). There was no significant difference in serum CC10 levels in asthmatic patients between the time of the asthmatic attack and the stable condition. Serum CC10 levels may reflect decreased production of CC10 caused by remodeling of the small airways in asthma.

Asthma↗

PubMed1999

Effects of troglitazone on fat distribution in the treatment of male type 2 diabetes.

We investigated the efficacy of additional administration of 400 mg troglitazone (+T), which became available as a treatment for type 2 diabetes following the demonstration of its ability to reduce insulin resistance, in combination with diet (D + T) or sulfonylurea (S + T) therapy. Body fat area as determined by computed tomographic (CT) scanning at the umbilical level, as well as several clinical and biochemical parameters of glycemic control and lipid metabolism, were compared before and after 3 months of additional treatment with troglitazone. The body mass index (BMI) tended to increase in both groups (22.7 +/- 0.6 v 23.2 +/- 0.6 kg/m2 in D + T, nonsignificant [NS]; 22.2 +/- 0.5 v 22.3 +/- 0.5 kg/m2 in S + T, NS), while it tended to decrease in the control group (only diet therapy, 23.6 +/- 0.6 v 23.1 +/- 0.8 kg/m2, NS). Mean blood pressure ([BP] 96 +/- 3 v 89 +/- 4 mm Hg, P < .05) decreased significantly in the D + T group. Changes in the glycemic and lipid profile and leptin did not reach statistical significance. The D + T group showed a significant decline in immunoreactive insulin ([IRI] 12.4 +/- 1.2 v 8.0 +/- 1.0 microU/mL, P < .05), reflecting markedly reduced insulin resistance, as well as a significant increase in plasma insulin-like growth factor-1 ([IGF-1] 175.7 +/- 14.2 v 189.8 +/- 12.6 ng/mL, P < .05). A slight weight gain was associated with a tendency for subcutaneous fat to increase, while visceral fat decreased in both troglitazone-treated groups. The decrease in the visceral to subcutaneous fat ratio (V/S ratio) was statistically significant in the D + T group (1.09 +/- 0.11 v 0.94 +/- 0.09, P < .05), while the V/S ratio in the control group did not change. A notable finding of this study is the difference in the response to troglitazone between subcutaneous and visceral adipose tissue. It is suggested that troglitazone may exert beneficial effects by reducing visceral fat.

Adipose Tissue↗

PubMed1999

Tolerance to vascularized organ allografts in large-animal models.

Although studies of tolerance induction in large animals remain limited compared with murine studies, a number of encouraging observations have been recently reported - especially in nonhuman primate models. The development of antibodies or proteins binding to costimulatory molecules and of an immunotoxin that is active on T cells have been particularly important advances leading to expanded opportunities for extending strategies for tolerance induction to large animals.

Abatacept↗

PubMed1999

Unresponsiveness of MyD88-deficient mice to endotoxin.

MyD88 is a general adaptor protein that plays an important role in the Toll/IL-1 receptor family signalings. Recently, Toll-like receptors 2 and 4 (TLR2 and TLR4) have been suggested to be the signaling receptors for lipopolysaccharide (LPS). In this study, we demonstrate that MyD88 knockout mice lack the ability to respond to LPS as measured by shock response, B cell proliferative response, and secretion of cytokines by macrophages and embryonic fibroblasts. However, activation of neither NF-kappaB nor the mitogen-activated protein (MAP) kinase family is abolished in MyD88 knockout mice. These findings demonstrate that signaling via MyD88 is essential for LPS response, but the inability of MyD88 knockout mice to induce LPS-dependent gene expression cannot simply be attributed to lack of the activation of MAP kinases and NF-kappaB.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Differential roles of TLR2 and TLR4 in recognition of gram-negative and gram-positive bacterial cell wall components.

Toll-like receptor (TLR) 2 and TLR4 are implicated in the recognition of various bacterial cell wall components, such as lipopolysaccharide (LPS). To investigate in vivo roles of TLR2, we generated TLR2-deficient mice. In contrast to LPS unresponsiveness in TLR4-deficient mice, TLR2-deficient mice responded to LPS to the same extent as wild-type mice. TLR2-deficient macrophages were hyporesponsive to several Gram-positive bacterial cell walls as well as Staphylococcus aureus peptidoglycan. TLR4-deficient macrophages lacked the response to Gram-positive lipoteichoic acids. These results demonstrate that TLR2 and TLR4 recognize different bacterial cell wall components in vivo and TLR2 plays a major role in Gram-positive bacterial recognition.

Animals↗

PubMed1999

A unique case of desmoplastic ameloblastoma of the mandible: report of a case and brief review of the English language literature.

A unique case of desmoplastic ameloblastoma is reported from the clinical, radiographic, and histologic viewpoints. The patient was a 56-year-old man who complained of a painless swelling on the buccal aspect of the left mandible. Periapical and panoramic radiographs revealed a rounded, slightly radiolucent area with blurred osteosclerotic margins. Occlusal radiograph and computed tomography images disclosed buccal bone expansion outlined by thinned cortices. Computed tomography images exhibited an enhanced area in the anterior portion of the lesion. Interestingly, the coronal computed tomography images revealed a close relationship between the periodontal membrane of the left mandibular second premolar and the enhanced area. Biopsy specimens from the anterior portion of the lesion displayed typical histologic features of the desmoplastic variant of ameloblastoma. However, those from the posterior portion disclosed a large cystic formation. Oxytalan fibers were identified in the stromal tissue of the tumor, which suggested that the tumor arose from the epithelial rests of Malassez in the periodontal membrane of the related tooth. We also reviewed previously reported 41 cases. In 36 of 38 cases in which the location was specified, the tumor was found in the anterior to premolar region of the maxilla or mandible. A radiographic description was given in only 29 previous cases, 28 of which involved multilocular lesions. No cyst as large as the one in the present case was found among the previously reported desmoplastic ameloblastomas. Although the present case deviates from the usual desmoplastic variant of ameloblastoma in terms of locus, radiologic appearance, and cyst formation, it still meets the histologic criteria for this variant in both the stromal and epithelial components.

Ameloblastoma↗

PubMed1999

Cemento-osseous dysplasia of the jaws in 54 Japanese patients: a radiographic study.

OBJECTIVE: The aim of this study was to describe the radiographic patterns of cemento-osseous dysplasia. STUDY DESIGN: Fifty-four patients affected with benign fibro-osseous jaw lesions that showed periapical radiopacities and/or radiolucencies in a focal or a multiplex form were studied. The clinical, radiographic, and histopathologic features of the patients with cemento-osseous dysplasia were retrospectively studied. Radiographic features of the cemento-osseous dysplasia lesions were classified according to the appearance of calcified bodies. Radiographic visibility of periodontal ligament spaces of related teeth was assessed. RESULTS: Forty-nine (91 %) of the 54 patients were women. The mean age of the total group was 50.8 years, and that of the male group was 64.6 years. The cemento-osseous dysplasia lesions could be classified into 6 types radiographically. Eighteen patients had at least 2 or more types of cemento-osseous dysplasia lesions. Of 147 related teeth, 142 had periodontal ligament spaces clearly visible. Six of 9 patients who had a total of 25 teeth with active hypercementosis showed concomitant occurrence of other types of cemento-osseous dysplasia lesions. Biopsy specimens showed various amounts of bonelike and cementumlike tissues. CONCLUSIONS: It is likely that cemento-osseous dysplasia consists of 3 variations of a single entity, all with the same unknown cause. In one variation, the entity originates from the periodontium; in another, it is of medullary bone origin; and in the third it results from the simultaneous involvement of both tissues.

Adult↗

PubMed1999

Human mannan-binding lectin inhibits the infection of influenza A virus without complement.

Mannan-binding lectin (MBL) is a C-type serum lectin that is believed to play an important role in innate immunity. It is one of the collectin family, which is characterized by having a collagen-like sequence and a carbohydrate recognition domain. MBL can bind to sugar determinants of several micro-organisms, neutralize them and inhibit infection by complement activation through the lectin pathway and opsonization by collectin receptors. Bovine conglutinin and mouse MBL inhibit the infective and haemagglutinating activities of influenza A viruses. To identify the direct antiviral activity of human MBL against influenza A viruses that does not depend on complement activation or opsonization, we isolated native MBL from human serum and produced a recombinant MBL in Chinese hamster ovary (CHO) cells using a pNOW/CMV-A expression vector system. Native and recombinant human MBL exhibited neutralization activity against A/Ibaraki/1/90 (H3N2), with the plaque focus reduction assay at the viral attachment phase. Their activities were inhibited by EDTA, mannose and anti-human MBL antibody. Furthermore, at the viral expansion phase both MBL in culture medium prevented viral spreading from primary infected cells to neighbour cells. A virus recovery study using EDTA indicated that interaction between MBL and virus was reversible and non-damaging to the virus. Lectin blot and immunohistochemistry assays showed that these antiviral activities involved binding between MBL and two viral envelope proteins, haemagglutinin and neuraminidase. These findings suggest that human MBL can play an important role in innate immunity by direct viral neutralization and inhibition of viral spread, as well as an indirect role through opsonization and complement activation.

Animals↗