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T Sasaki

Publications and source records attributed to T Sasaki.

At least 127 records · Page 7Linked to original sources
PubMed2002

Detection of maternal-fetal microchimerism in the inflammatory lesions of patients with Sjögren's syndrome.

BACKGROUND: A possible relation between maternal-fetal microchimerism and autoimmune diseases with some similarities to chronic graft versus host disease (cGVHD) has been reported. OBJECTIVE: To investigate whether cells with male DNA exist in female patients with Sjögren's syndrome (SS) as SS has clinical features similar to those of cGVHD. METHODS: DNA was extracted from 27 samples of peripheral blood mononuclear cells (PBMC), 42 biopsy samples of labial salivary glands (LSG), and nine samples of bronchoalveolar lavage fluid (BALF) cells from 56 female patients with SS. The presence of male DNA was determined by nested polymerase chain reaction (PCR) and by fluorescence in situ hybridisation (FISH). RESULTS: Among 56 female patients with SS, 42 patients had at least one male child. Among those 42 patients, none of the 22 PBMC but 10/28 (36%) LSG samples tested positive by PCR for the Y chromosome-specific sequence (p=0.0013). The Y chromosome-specific sequence was not detected in the samples of LSG in 10 patients without SS. In the BALF samples 2/9 (22%) patients with SS tested positive by PCR. Cells containing the Y chromosome were shown to exist in all the LSG specimens from three female patients with SS by FISH. CONCLUSIONS: Maternal-fetal microchimerism was shown for the first time to exist in the salivary glands and lungs of female patients with SS in this study. The presence of non-host cells in the inflammatory lesions but not in the peripheral blood suggests a possible role for maternal-fetal microchimerism in the pathogenesis of SS.

Adolescent↗
PubMed2002

[Genetic divergence of Far Eastern dace species belonging to the genus Tribolodon (Pisces, Cyprinidae) and closely related taxa].

Based on a biochemical-genetic approach, heterozygosity and divergence of structural genes of 30 enzyme loci were analyzed in six dace species. In addition, intra- and interspecific divergence of gene expression was analyzed based on a sample of 12 to 15 loci. Mean heterozygosities per individual varied as follows: Tribolodon species, Hobs = 0.007 +/- 0.007 and Hexp = 0.007 +/- 0.007; T. ezoe, Hobs = 0.045 +/- 0.016 and Hexp = 0.067 +/- 0.029. Several variants of genetic distances were estimated. Standard Nei's distances (DN) varied from 0.145 to 0.284 in four dace species studied. As related to Tribolodon dace species, the following genetic distances were obtained for two members of other genera: Pseudaspius leptocephalus, DN = 0.269; Leuciscus waleckii, DN = 0.769. Based on the distance matrices, different clustering algorithms were realized. The main feature shared by different dendrograms was a separate position of the cluster joining Far-Eastern dace species, to which P. leptocephalus and L. waleckii are successively added. Among the species studied, the proportion of loci similar by expression (E) varied from 87 to 100%. The greatest difference was found between anadromous and nonanadromous ecotypes of T. hakonensis, E = 67%. The following conclusions can be made: (1) Four studied species of the genus Tribolodon are rather well genetically differentiated. Diagnostic loci are available. (2) A nominal dace species, T. species, should be considered the fourth isolated species of this genus, which is confirmed by its recent zoological acceptance of this species. (3) The origin and divergence of dace species belonging to the genus Tribolodon are relatively late (1 to 3 Myr ago) historical events. (4) Taxonomically, the genus Tribolodon belong to the tribe Pseudaspinini together with P. leptocephalus, which is confirmed by genetic data. (5) Data on heterozygosity and the divergence of structural and regulatory elements of genome, along with the proposed scheme of speciation types, suggest the following speciation modes for the species studied: for four species, adaptive divergence and for two species, genetic transformation.

Animals↗
PubMed2001

Genomic structure and regulation of a novel human gene, Klp1.

Klp1 (K562 cells-derived leucine zipper-like protein 1) is a transcription factor which binds to the coproporphyrinogen oxidase promoter regulatory element (GGACTACAG). In order to clarify the function of Klp1, we determined the complete human Klp1 genomic structure and regulatory element in the promoter region. The gene spans about 2.4 kb and has three exons. Its promoter region has multiple GC boxes, E2F binding site, one cAMP response element (CRE), and no TATA box with multiple transcription initiation sites, which is characteristic of housekeeping and growth regulating genes. Promoter analysis showed that the promoter was more active in K562 cells entered into the cell cycle by serum stimulation than quiescent cells. Further promoter analysis revealed that CRE at -42 is essential for full promoter activity, and c-Jun and activation transcription factor 1/cAMP response element binding protein 1 proteins bind to this element. These structural characteristics and the promoter function suggest that Klp1 may play a role in cell cycle regulation.

Base Sequence↗
PubMed2001

Syntheses and absolute stereochemistries of UPA0043 and UPA0044, cytotoxic antibiotics having a p-quinone-methide structure.

The first syntheses of new antibiotics UPA0043 and UPA0044 were accomplished starting from commercially available 18beta-glycyrrhetinic acid and vanillin. The present syntheses involve the coupling of a sesquiterpenoid aldehyde and an aryllithium, the stereoselective formation of a p-quinone-methide system, and regioselective intramolecular cyclization via an epoxy ring opening. [reaction: see text]

Antibiotics, Antineoplastic↗
PubMed2001

Superconducting gap structure of kappa-(BEDT-TTF)2Cu(NCS)2 probed by thermal conductivity tensor.

The thermal conductivity of organic superconductor kappa-(BEDT-TTF)2Cu(NCS)2 (Tc = 10.4 K) has been studied in a magnetic field rotating within the 2D superconducting planes with high alignment precision. At low temperatures ( T < or = 0.5 K), a clear fourfold symmetry in the angular variation, which is characteristic of a d-wave superconducting gap with nodes along the directions rotated 45 degrees relative to the b and c axes of the crystal, was resolved. The determined nodal structure is inconsistent with recent theoretical predictions of superconductivity induced by the antiferromagnetic spin fluctuation.

Journal Article↗
PubMed2001

Molecular cloning of a member of the facilitative glucose transporter gene family GLUT11 (SLC2A11) and identification of transcription variants.

We isolated a member of the facilitative glucose transporter (GLUT) gene family (GLUT11; SLC2A11 as a HGMW-approved symbol) based on the analysis of a human genomic BAC clone KB1125A3 located on band q11.2 of human chromosome 22. The gene GLUT11/SLC2A11 consists of 12 exons spanning over 29 kb in size and is located between two genes, SMARCB1 and MIF. The deduced amino acid sequence indicated the topological features of transmembrane helices and sequence motifs which are common to the GLUT protein family. The cDNA cloning revealed the presence of three types of variation in its transcripts. The first variation is caused by the existence of three distinct first exons (SLC2A11-a, -b, and -c). PCR analysis of multi-tissue-derived cDNA panels indicated the differential expression of these transcript variants. The second variation is caused by skipping over one exon (exon 6). The third variation is caused by the premature transcription termination at a site between exon 8 and exon 9. Both exon skipping and premature termination caused frameshift, resulting in the production of truncated GLUT11/SLC2A11 transcripts. These results suggested that transcription of GLUT11/SCL2A11 gene is controlled in a complex manner.

Amino Acid Motifs↗
PubMed2001

Short arm region of laminin-5 gamma2 chain: structure, mechanism of processing and binding to heparin and proteins.

Laminin-5 is a typical component of several epithelial tissues and contains a unique gamma2 chain which can be proteolytically processed by BMP-1. This occurs in the N-terminal half of the gamma2 chain (606 residues), which consists of two rod-like tandem arrays of LE modules, LE1-3 and LE4-6, that flank a globular L4m module containing the cleavage site. Recombinant analysis of L4m, which includes an additional imperfect LE module essential for proper folding, demonstrated an unusual pattern of disulfide bonding. These connectivities prevented the release of gamma2LE1-3L4 m after BMP-1 cleavage which required in addition disulfide reshuffling by isomerases. The liberated segment bound through its L4 m module to heparin, nidogen-1, fibulin-1 and fibulin-2. A further heparin/sulfatide-binding site could be attributed to some arginine residues in module LE1. The gamma2LE4-6 segment remaining in processed laminin-5 showed only a strong binding to fibulin-2. Immunological studies showed a similar partial processing in cell culture and tissues and the persistence of the released fragment in tissues. This indicated that both N-terminal regions of the gamma2 chain may have a function in vivo.

Amino Acid Sequence↗
PubMed2001

Domain IVa of laminin alpha5 chain is cell-adhesive and binds beta1 and alphaVbeta3 integrins through Arg-Gly-Asp.

The globular domain IVa from the short arm region of mouse laminin alpha5 chain was obtained by recombinant production and shown to be a cell-adhesive substrate and to bind alphaVbeta3 integrin in solid-phase assays. These interactions were blocked by RGD peptides and a restricted panel of anti-integrin antibodies. The two RGD sequences present in alpha5IVa were shown by site-directed mutagenesis to make different contributions to cell adhesion but were equivalent in binding alphaVbeta3 integrin. A quantitative radioimmuno-inhibition assay was established based on domain alpha5IVa which demonstrated distinct amounts of alpha5 chain in various tissues, particularly in vessel walls. There it could play a role in angiogenesis steps requiring RGD-dependent integrins.

Animals↗
PubMed2001

Porcine enamel matrix derivative enhances trabecular bone regeneration during wound healing of injured rat femur.

To elucidate the effects of enamel matrix derivative (EMD: Emdogain) on bone regeneration in rat femurs after drill-hole injury, defects in bone were filled with either EMD or its carrier, PGA, as control. On postoperative days 4 to 28, dissected femurs were examined by means of various morphological approaches. In both experimental groups, formation of trabecular bone, which was immunostained for bone sialoproteins (BSP), had occurred in the medullary cavities at cylindrical bone defects on Day 7 postoperatively. Cuboidal osteoblasts were clearly observed on these newly-formed BSP-positive bone trabeculae. On Days 7 and 14, many multinucleated giant cells, which strongly expressed cathepsin K, had appeared on these bone trabeculae, indicating active bone remodeling. In these bone trabeculae, Ca and P weight % and Ca/P ratio were similar to those of cortical bone, and there was no significant difference between the PGA- and EMD-applied groups. Bone volume fraction of newly-formed bone trabeculae on Day 7 postoperatively was significantly higher in the EMD-applied group than in the PGA-applied controls. Because of active bone remodeling and the marked decrease of bone volume, on Days 14 and 28 postoperatively, however, there was no longer a significant difference in trabecular bone volume fraction between the experimental groups. Our results suggest that EMD possesses an osteo-promotive effect on bone and medullary regeneration during wound healing of injured long bones.

Animals↗
PubMed2001

Sphingosine 1-phosphate contracts canine basilar arteries in vitro and in vivo: possible role in pathogenesis of cerebral vasospasm.

BACKGROUND AND PURPOSE: Sphingosine 1-phosphate (S1P) is a platelet-derived bioactive lipid that exerts a variety of biological responses, including vasocontraction. To understand the involvement of S1P in cerebral vasospasm, we investigated the effect of S1P on vasocontraction of the canine basilar artery in vitro and in vivo. METHODS: We recorded isometric tension in basilar arterial rings from dogs in vitro and estimated time-course changes in the diameter of canine basilar arteries and the S1P concentration in cerebrospinal fluid (CSF) by angiography and radioreceptor assays, respectively, after administering S1P into the cisterna magna. Changes in the supernatant S1P concentration during clot formation were monitored by using the in vitro subarachnoid hemorrhage model, in which blood is mixed with CSF. RESULTS: At concentrations ranging between 100 nmol/L and 10 micromol/L, S1P induced a dose-dependent contraction of the basilar artery in vitro. This effect was significantly inhibited by Y-27632, a highly selective Rho-kinase inhibitor. The administration of S1P into the CSF induced a 60% to 70% decrease in the arterial diameter within 15 minutes, and vasocontraction continued for 2 days thereafter. The concentration of S1P in the supernatant during clot formation in vitro reached approximately 300 nmol/L. CONCLUSIONS: S1P induces vasocontraction in the canine basilar artery in vitro and in vivo, possibly through a mechanism involving activation of the Rho/Rho-kinase pathway. Thus, S1P might be considered as a novel spasmogenic substance involved in cerebral vasospasm after subarachnoid hemorrhage.

Amides↗
PubMed2001

Involvement of phosphoinositide 3-kinases in neutrophil activation and the development of acute lung injury.

Activated neutrophils contribute to the development and severity of acute lung injury (ALI). Phosphoinositide 3-kinases (PI3-K) and the downstream serine/threonine kinase Akt/protein kinase B have a central role in modulating neutrophil function, including respiratory burst, chemotaxis, and apoptosis. In the present study, we found that exposure of neutrophils to endotoxin resulted in phosphorylation of Akt, activation of NF-kappaB, and expression of the proinflammatory cytokines IL-1beta and TNF-alpha through PI3-K-dependent pathways. In vivo, endotoxin administration to mice resulted in activation of PI3-K and Akt in neutrophils that accumulated in the lungs. The severity of endotoxemia-induced ALI was significantly diminished in mice lacking the p110gamma catalytic subunit of PI3-K. In PI3-Kgamma(-/-) mice, lung edema, neutrophil recruitment, nuclear translocation of NF-kappaB, and pulmonary levels of IL-1beta and TNF-alpha were significantly lower after endotoxemia as compared with PI3-Kgamma(+/+) controls. Among neutrophils that did accumulate in the lungs of the PI3-Kgamma(-/-) mice after endotoxin administration, activation of NF-kappaB and expression of proinflammatory cytokines was diminished compared with levels present in lung neutrophils from PI3-Kgamma(+/+) mice. These results show that PI3-K, and particularly PI3-Kgamma, occupies a central position in regulating endotoxin-induced neutrophil activation, including that involved in ALI.

Animals↗
PubMed2001

Immunolocalization of vacuolar-type H+-ATPase, cathepsin K, matrix metalloproteinase-9, and receptor activator of NFkappaB ligand in odontoclasts during physiological root resorption of human deciduous teeth.

To investigate the cellular mechanisms of physiological root resorption in human deciduous teeth, the authors examined the immunocytochemical localization of vacuolar-type H+-ATPase, a lysosomal cysteine proteinase, cathepsin K, matrix metalloproteinase-9 (MMP-9), and receptor activator of NFKB ligand (RANKL) in odontoclasts. H+-ATPase, cathepsin K, and MMP-9 are the most important enzymes for decalcification of apatite crystals and degradation of type-I collagen. In addition, RANKL is one of the key regulatory molecules in osteoclast formation and functions. Odontoclasts developed extensive ruffled borders and clear zones apposed to the resorbing root dentine surfaces. On immunoelectron microscopy, the expression of vacuolar-type H+-ATPase was detected along the limiting membranes of pale vacuoles and the ruffled border membranes of odontoclasts. Cathepsin K in odontoclasts was localized within pale vacuoles, lysosomes, the extracellular canals of ruffled borders, and the underlying resorbing dentine surfaces. MMP-9 localization in odontoclasts was similar to those of cathepsin K. RANKL was detected in both mononuclear stromal cells and odontoclasts located on resorbing dentine surfaces. These results suggest that (1) odontoclasts are directly involved in decalcification of apatite crystals by active extrusion of proton ions mediated by H+-ATPase and (2) extracellular degradation of dentine type-I collagen by both cathepsin K and MMP-9, and (3) odontoclast differentiation and activity are regulated, at least in part, by RANKL, possibly produced by mononuclear stromal cells and odontoclasts themselves in the resorbing tissues. Thus, the cellular mechanisms of physiological root resorption appear to be quite similar to those of osteoclastic bone resorption.

Carrier Proteins↗
PubMed2001

Drebrin expression is increased in spinal motoneurons of rats after axotomy.

Drebrin has been known to act on actin filaments at dendritic spines to cause morphological change, and might be related to the plasticity of synaptic transmission. In the present study, changes of drebrin were examined immunohistochemically in the spinal motoneurons of rats following unilateral sciatic nerve transection. Drebrin-immunoreactivity (-ir) in the motoneurons was significantly increased on the lesioned side after 3 days. Confocal laser-scanning microscopic images of the motoneurons revealed conspicuous increase in drebrin in the submembranous region of the cells. After 10 weeks, drebrin-ir on the lesioned side decreased to a level not significantly different from that on the unlesioned side. The results suggested that drebrin played important roles in synaptic restoration in axotomized motoneurons.

Animals↗
PubMed2001

The stress kinase mitogen-activated protein kinase kinase (MKK)7 is a negative regulator of antigen receptor and growth factor receptor-induced proliferation in hematopoietic cells.

The dual specificity kinases mitogen-activated protein kinase (MAPK) kinase (MKK)7 and MKK4 are the only molecules known to directly activate the stress kinases stress-activated protein kinases (SAPKs)/c-Jun N-terminal kinases (JNKs) in response to environmental or mitogenic stimuli. To examine the physiological role of MKK7 in hematopoietic cells, we used a gene targeting strategy to mutate MKK7 in murine T and B cells and non-lymphoid mast cells. Loss of MKK7 in thymocytes and mature B cells results in hyperproliferation in response to growth factor and antigen receptor stimulation and increased thymic cellularity. Mutation of mkk7 in mast cells resulted in hyperproliferation in response to the cytokines interleukin (IL)-3 and stem cell factor (SCF). SAPK/JNK activation was completely abolished in the absence of MKK7, even though expression of MKK4 was strongly upregulated in mkk7(-/-) mast cell lines, and phosphorylation of MKK4 occurred normally in response to multiple stress stimuli. Loss of MKK7 did not affect activation of extracellular signal-regulated kinase (ERK)1/2 or p38 MAPK. mkk7(-/-) mast cells display reduced expression of JunB and the cell cycle inhibitor p16INK4a and upregulation of cyclinD1. Reexpression of p16INK4a in mkk7(-/-) mast cells abrogates the hyperproliferative response. Apoptotic responses to a variety of stimuli were not affected. Thus, MKK7 is an essential and specific regulator of stress-induced SAPK/JNK activation in mast cells and MKK7 negatively regulates growth factor and antigen receptor-driven proliferation in hematopoietic cells. These results indicate that the MKK7-regulated stress signaling pathway can function as negative regulator of cell growth in multiple hematopoietic lineages.

Animals↗
PubMed2001

The genomic structure and promoter region of the human parkin gene.

Parkin has been identified as a causative gene of the autosomal recessive juvenile parkinsonism (AR-JP). In this study, we determined the genomic structure of the Parkin gene and identified a core promoter region based on the DNA sequence of 1.4 Mb. The 5'-flanking region contained no apparent TATA or CAAT box elements but several putative cis-elements for various transcription factors. The GC- and CpG-rich regions were observed not only in the 5'-flanking sequence but also in the 5'-part of the first intron of Parkin. We identified an exact starting point of Parkin transcription. A core promoter region was determined by transfecting a series of deletion constructs with a dual luciferase reporter system into human neuroblastoma cells. Furthermore, we located a neighboring novel gene in a head-to-head direction with Parkin with only a 198-bp interval.

Base Sequence↗
PubMed2001

Modification of the laminin alpha 4 chain by chondroitin sulfate attachment to its N-terminal domain.

The N-terminal domain of laminin alpha 4 chains corresponds to a short rod-like structure which after recombinant production was found to be modified by chondroitin sulfate. Substitution occurred mainly to a single serine in its N-terminal ASGDG sequence. A similar yet partial modification was also demonstrated for the alpha 4 chain present in extracts of adult mouse tissues. Antibodies to the fragment were useful to demonstrate a relatively high content of alpha 4 in several tissues and for the immunolocalization in various blood vessels, some basement membranes and interstitial regions.

Animals↗
PubMed2001

Novel and recurrent mutations in lamin A/C in patients with Emery-Dreifuss muscular dystrophy.

Emery-Dreifuss muscular dystrophy (EDMD) is characterized by slowly progressive muscle wasting and weakness; early contractures of the elbows, Achilles tendons, and spine; and cardiomyopathy associated with cardiac conduction defects. Clinically indistinguishable X-linked and autosomal forms of EDMD have been described. Mutations in the STA gene, encoding the nuclear envelope protein emerin, are responsible for X-linked EDMD, while mutations in the LMNA gene encoding lamins A and C by alternative splicing have been found in patients with autosomal dominant, autosomal recessive, and sporadic forms of EDMD. We report mutations in LMNA found in four familial and seven sporadic cases of EDMD, including seven novel mutations. Nine missense mutations and two small in-frame deletions were detected distributed throughout the gene. Most mutations (7/11) were detected within the LMNA exons encoding the central rod domain common to both lamins A/C. All of these missense mutations alter residues in the lamin A/C proteins conserved throughout evolution, implying an essential structural and/or functional role of these residues. One severely affected patient possesed two mutations, one specific to lamin A that may modify the phenotype of this patient. Mutations in LMNA were frequently identified among patients with sporadic and familial forms of EDMD. Further studies are needed to identify the factors modifying disease phenotype among patients harboring mutations within lamin A/C and to determine the effect of various mutations on lamin A/C structure and function.

Adult↗