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Biomedical subjects

Kenji Watanabe

Publications and source records attributed to Kenji Watanabe.

At least 73 records · Page 4Linked to original sources
PubMed2003

Insight into a natural Diels-Alder reaction from the structure of macrophomate synthase.

The Diels-Alder reaction, which forms a six-membered ring from an alkene (dienophile) and a 1,3-diene, is synthetically very useful for construction of cyclic products with high regio- and stereoselectivity under mild conditions. It has been applied to the synthesis of complex pharmaceutical and biologically active compounds. Although evidence on natural Diels-Alderases has been accumulated in the biosynthesis of secondary metabolites, there has been no report on the structural details of the natural Diels-Alderases. The function and catalytic mechanism of the natural Diels-Alderase are of great interest owing to the diversity of molecular skeletons in natural Diels-Alder adducts. Here we present the 1.70 A resolution crystal structure of the natural Diels-Alderase, fungal macrophomate synthase (MPS), in complex with pyruvate. The active site of the enzyme is large and hydrophobic, contributing amino acid residues that can hydrogen-bond to the substrate 2-pyrone. These data provide information on the catalytic mechanism of MPS, and suggest that the reaction proceeds via a large-scale structural reorganization of the product.

Alcohols↗
PubMed2003

A simple "soaking method" for RNA interference in the planarian Dugesia japonica.

A simple method was developed for RNA interference (RNAi) in the planarian Dugesia japonica. The DjIFb ( Dugesia japonica intermediate filament b) gene was used to evaluate the effect of RNAi because both the cDNA and an antiserum against the gene product were available. After transverse cutting at the pre- and post-pharyngeal regions, the middle part of the body fragment was soaked in water containing double-stranded RNA (dsRNA) for about 5 h and then allowed to regenerate in water. On the 5th day of regeneration, little DjIFb protein was detected in the new tissues. When the worms were cut after soaking in dsRNA water, no RNAi effect was observed, suggesting that the dsRNA was introduced through the cut surface. A high concentration of dsRNA or repeated "cutting and soaking" resulted in more effective RNAi. This simple soaking method in combination with expressed sequence tag analysis should be very useful for high-throughput analyses of gene functions in planarian regeneration.

Animals↗
PubMed2003

Enhanced expression of B7.2 (CD86) by percutaneous sensitization with house dust mite antigen.

House dust mite antigen is a well-known allergen in the pathogenesis of atopic dermatitis (AD), a chronic relapsing inflammatory skin disease. We evaluated the AD model mice sensitized with house dust mite antigen and observed a Th2-dominant immune response. In this experiment, BALB/c mice were sensitized percutaneously with house dust mite antigen three times with 7 days interval after skin barrier disruption. A remarkable infiltration of polymorphonuclear granulocytes and monocytes in the cutis was observed in mice treated with this antigen, high serum IgE levels and IL-4 mRNA expression in local lymph node cells was also observed. CD19(+) B cell numbers overturned to CD4(+) helper T cells. In these mice, there was significant increase of B7.2 (CD86) expression on CD19(+) B cells. These results indicate that house dust mite antigen sensitizes BALB/c mice and skews their Th1/Th2 balance toward Th2.

Administration, Cutaneous↗
PubMed2003

Mediolateral intercalation in planarians revealed by grafting experiments.

We investigated how planarians organize their left-right axis by using ectopic grafting. Planarians have three body axes: anteroposterior (A-P), dorsoventral (D-V), and left-right (L-R). When a small piece is implanted into an ectopic region along the A-P and D-V axes, intercalary structures are always formed to compensate for positional gaps. There are two hypotheses regarding L-R axis formation in this organism: first, that the left and right sides of the animal may be recognized as different parts, and L-R intercalation can induce midline structures (asymmetry hypothesis); second, that both sides may have symmetrical positional values, and mediolateral (M-L) intercalation creates positional values along the L-R axis (symmetry hypothesis). We performed ectopic grafting experiments in the head region of the planarian, Dugesia japonica, to examine these hypotheses. A left lateral fragment containing a left auricle was implanted into the medial region of the host. Ectopic structures were always formed only on the left side of the graft, where lateral tissues abutted onto the medial tissues. However, no morphologic change was induced on the right side of the graft, where left-sided tissues faced onto right-sided tissues. Molecular marker analyses indicated that ectopic structures formed on the left side of the graft were induced by M-L intercalation, supporting the "symmetry hypothesis." When the midline tissues were implanted into a lateral region, they induced a complete ectopic head, demonstrating that M-L intercalation may be sufficient to establish the L-R axis in planarians.

Animals↗
PubMed2003

Crohn's disease complicated by adult-onset Still's disease.

A 31-year-old man with Crohn's disease developed arthritis, spiking fever, and skin rash indistinguishable from that of adult-onset Still's disease. He was admitted to our hospital because of a periumbilical intestinal skin fistula. Crohn's disease had been diagnosed in 1991, and had required intestinal resection twice, and schizophrenia had been diagnosed in 1993. He developed polyarthritis and spiking fever, accompanied by a macular skin rash on both forearms. Marked hepatosplenomegaly and bilateral pleural effusion were detected on computed tomography examination. These findings are indistinguishable from those of adult-onset Still's disease. Because his mental status had deteriorated following high-dose prednisolone on a previous admission, he was treated with an immunosuppressive agent on this occasion, with the treatment being successful. This is the first report of adult-onset Still's disease complicating Crohn's disease. In patients with Crohn's disease, polyarthritis and skin rash can easily be misdiagnosed as enteropathic arthritis with erythema nodosum associated with the Crohn's disease. Although adult-onset Still's disease may not be fatal, early diagnosis is important because it can, in rare cases, result in life-threatening complications.

Adult↗
PubMed2003

The expression of planarian brain factor homologs, DjFoxG and DjFoxD.

Recent accumulating evidence revealed that planarian central nervous system (CNS) has numerous functional domains distinguished by a large number of neural markers, suggesting that primitive animals which developed CNS already had the framework of the brain development. It is of interest to investigate genes which have been acquired at an early stage of evolution for brain pattern formation. One such candidate is FoxG1 (BF-1), specifically expressed in the telencephalon and implicated in brain development. We identified a FoxG1 (BF-1) homolog gene in planarians (DjFoxG). We also identified a FoxD class gene, DjFoxD. DjFoxG is expressed in the body and brain, with strong expression in the mesenchyme surrounding the gut. During regeneration, an intense anterior signal is detected, but this is not restricted to the head. DjFoxD is expressed in the mid-apex of the head, between the two lobes of the brain. Strong expression was detected in the mid-anterior blastema. Thus, FoxG and FoxD homologs do exist in planarians, but are regulated differently than those in vertebrates.

Amino Acid Sequence↗
PubMed2003

Outpatient treatment of moderately severe active ulcerative colitis with pulsed steroid therapy and conventional steroid therapy.

Pulsed steroid therapy may induce rapid remission in patients with moderately severe ulcerative colitis in outpatient clinics. A total of 19 patients with moderately severe active ulcerative colitis who refused hospitalization were treated between October 1999 and September 2001 in the outpatient clinic. Patients were treated with either conventional oral steroid therapy or intravenous pulsed steroid therapy followed by conventional oral steroid therapy. Eight patients received conventional steroid therapy and 11 patients received pulsed steroid therapy followed by conventional steroid therapy. The efficacies of the two types of steroid therapy were equal, but patients with active colitis responded more quickly to pulsed steroid therapy than to conventional steroid therapy. No serious adverse effects were observed. Moderately severe colitis can be safely treated with either conventional or pulsed steroid therapy in the outpatient clinic, but pulsed steroid therapy may induce clinical remission more quickly than conventional steroid therapy.

Administration, Oral↗
PubMed2003

Aberrant utilization of nitric oxide and regulation of soluble guanylate cyclase in rat diabetic retinopathy.

Although nitric oxide (NO) was shown not only to exert biological activities through activation of soluble guanylate cyclase (sGC), but also to cause oxidative stress, mechanisms for switching these pathways are unknown. This study aimed to examine aberrant utilization of NO under disease conditions such as diabetes mellitus. Diabetes was induced in male Wistar rats by injecting streptozotocin (STZ; 50 mg/kg body weight, i.p.). Retina was perfusion-fixed for immunohistochemistry to detect the gas-mediated activation of sGC by anti-sGC antibodies that are function-sensitive [monoclonal antibody (MoAb) 3221] and -insensitive (MoAb28131). Regional lipid peroxidation was also examined by an anti-acrolein MoAb. At 6 weeks after STZ injection, inducible NO synthase induction became evident, coinciding with the overproduction of nitrotyrosine, followed by that of acrolein. Despite such NO overproduction, sGC did not exhibit any notable activation. When STZ-treated animals were posttreated with a derivative of superoxide dismutase that stays in circulation without undergoing renal ultrafiltration, immunoreactivities to MoAb3221 but not to MoAb28131 increased markedly in diabetic retina, suggesting that superoxide cancels free NO for local sGC activation. These results provide evidence of aberrant utilization of NO and suggest that superoxide plays a role in interfering with NO-mediated sGC activation for phototransducing events in this neural tissue.

Animals↗
PubMed2003

Distinct elevation of levels of anti-Caenorhabditis elegans antibody in sera of patients with inflammatory bowel disease.

Dysregulation of immune responses to intestinal exogenous antigens contributes to the pathogenesis of inflammatory bowel disease, but the specific antigen responsible for the pathogenesis of inflammatory bowel disease is unknown. We measured serum antibody titers against Caenorhabditis elegans antigens. Immunoglobulin G (IgG) and IgG subclass anti-C. elegans antibodies in serum samples from 29 patients with ulcerative colitis, 30 patients with Crohn's disease, 7 patients with intestinal Behçet's disease, and 11 healthy controls were measured by enzyme-linked immunosorbent assay. Serum IgG and IgG2 antibody titers against C. elegans were significantly higher in patients with inflammatory bowel disease than in controls. Antibody levels were not affected by age, gender, disease activity, extent of disease, or small bowel involvement. The anti-C. elegans antibody titer was significantly lower in patients with Crohn's disease taking mesalazine or sulfasalazine than in patients not taking these drugs. The increased immune responses to C. elegans found in patients with inflammatory bowel disease reflect dysregulated immune responses to enteric antigens, which might play a role in the pathogenesis of inflammatory bowel disease.

Adult↗
PubMed2003

Inhibitory effects of antiparkinsonian drugs and caspase inhibitors in a parkinsonian flatworm model.

It has been known that rotenone and 1-methyl-4-phenylpyridinium ion (MPP(+), a metabolite of MPTP), which inhibit mitochondrial complex I, are useful tools for parkinsonian models in vertebrates such as primates and rodents. Planarian, an invertebrate flatworm, has a high potential for regeneration, and dopamine plays a key role in its behavior. In the present study, we examined a cloned planarian, the GI strain from Dugesia japonica. Planarians that were treated with rotenone or MPTP underwent autolysis and individual death in a concentration- and time-dependent manner. In addition, these effects induced by rotenone or MPTP were inhibited by several antiparkinsonian drugs and caspase inhibitors. These results suggest that the degeneration of planarian dopaminergic system induced by rotenone or MPTP may be mediated through caspase-like activation.

Animals↗
PubMed2003

Changes in respiratory condition after thymectomy for patients with myasthenia gravis.

BACKGROUND: Anesthesia without muscle relaxants has been reported to be effective for early extubation after thymectomy, but postoperative respiratory status of the patients has not been studied intensively. METHODS: Fifty-two consecutive patients undergoing thymectomies for myasthenia gravis (MG) were evaluated. RESULTS: Forty-two (81%) of the 52 patients were extubated in the operating room, and 49 (94%) patients were extubated within 24 hours. However, 6 (12%) patients required subsequent reintubation for respiratory support. There was a sudden increase in the respiratory rate (RR) and PaCO(2). The mean value of the increase in PaCO(2) at the time of reintubation was 23 mmHg (12-58 mmHg). The mean value of the increase in RR above the preoperative level at the time of reintubation was 16/min (7-30/min). In univariate analysis, vital capacity (VC), %VC, the preoperative pyridostigmine dose and the duration of surgery correlated with reintubation, but with multivariate analyses, the pyridostigmine dose was the only significant factor related to reintubation. CONCLUSION: The patients who received at least or more than 240 mg of pyridostigmine should be monitored carefully after tracheal extubation.

Adolescent↗
PubMed2003

Differential expression of homing receptor CD103 on lamina propria lymphocytes and association of CD103 with epithelial adhesion molecules in inflammatory bowel disease.

Intraepithelial lymphocytes play an important role in mucosal immunology, and are involved in the pathogenesis of inflammatory bowel disease. We studied expression of CD103 on mucosal lymphocytes with epithelial adhesion molecules in patients with inflammatory bowel disease. Surgical specimens of human colon were obtained from 12 patients with ulcerative colitis, 12 patients with Crohn's disease, and 5 controls. Frozen sections were cut and expression of CD103 on lymphocytes, E-cadherin, CD44V3, and CD44v6 on intestinal epithelium was studied. Frequency of CD103-positive intraepithelial lymphocytes did not differ among controls, patients with ulcerative colitis, and patients with Crohn's disease. The frequency of CD103-positive lamina propria lymphocytes was significantly higher in patients with Crohn's disease than in controls and patients with ulcerative colitis. The frequency of CD103-positive intraepithelial lymphocytes was significantly correlated with that of lamina propria lymphocytes in patients with ulcerative colitis. The frequency of CD103-positive intraepithelial lymphocytes was significantly correlated with epithelial E-cadherin expression but that of lamina propria lymphocytes was not. Differential up-regulation of CD103 expression on lamina propria lymphocytes in Crohn's disease may indicate differential humoral or cellular regulation in inducing CD103 molecules on lymphocytes in patients with this disease.

Antigens, CD↗
PubMed2003

[A case of brain abscess associated with asymptomatic multiple myeloma].

A 55-year-old male was admitted to our hospital because of confusion and mild weakness of his left arm and leg. His condition had taken a gradual turn for the worse for several months. Computed tomography (CT) demonstrated a mixed density mass with multiple cysts and massive perifocal edema. Magnetic resonance imaging (MRI) demonstrated an irregular-shaped mass with multiple cysts sized 6 x 4 x 6 cm in the temporal lobe, which manifested mixed signal intensity on both the T1 weighted image and the T2 weighted image. MRI also revealed massive perifocal edema and marked midline shift. Gd-DTPA study showed ring-like enhancement. Angiography showed no tumor stain and a suppressed right posterior cerebral artery. A right extended temporo-occipital craniotomy was performed to extirpate the abscess subtotally. The histological examination showed brain abscess and Gram stain of the pus revealed the presence of gram-positive bacilli. The gram-positive bacillus, Corynebacterium only was subsequently cultured from the pus. After the operation his hemiparesis seemed to disappear. In spite of the treatment with multiple intravenous antibiotics, his hemiparesis worsened again. CT and MRI demonstrated recurrence of the brain abscess in the occipital lobe and marked perifocal edema. The second operation was performed and removed all the infected brain tissue with abscess. After the second operation, otorhinological and cardiovascular examinations were carried out, but no causal disease was found. Immunoelectrophoresis (total protein 12.2 g/d/) revealed the peak of M protein. Bone marrow revealed dysplasia of the plasma cell and he was diagnosed as having multiple myeloma that had made him an immunocompromised host.

Brain Abscess↗
PubMed2002

Induction of a noggin-like gene by ectopic DV interaction during planarian regeneration.

In previous studies, we have shown that dorsoventral (DV) interaction evokes not only blastema formation, but also morphogenetic events similar to those that occur in regeneration. However, it is still unclear what kinds of signal molecules are involved in the DV interaction. To investigate the signal systems involved in the DV interaction, we focused on a noggin-like gene (Djnlg) identified by the planarian EST project. Djnlg is the first noggin homologue isolated from an invertebrate. In DjNLG, the positions of nine cysteine residues which may be essential for dimer formation were well conserved, but overall, the amino acid sequence of DjNLG did not show high similarity to the sequences of vertebrate Noggins. Expression of Djnlg was observed only in the proximal region of the branch structures in the brain of intact planarians, suggesting that Djnlg may have a role in pattern formation in the brain. Interestingly, transient strong expression of Djnlg was observed in the amputated region of regenerating planarians. Djnlg-expressing cells were detected beneath the muscle 9 h after amputation and were then detected in the ventral subepidermal region of the blastema. The induction of Djnlg expression by amputation was not affected by X-ray irradiation, even though the stem cells were completely eliminated, implying the existence of signal-producing cells which may provide a positional cue to the stem cells. In DV reversed grafting, expression of Djnlg was strongly induced in the DV boundary between the host and donor. These results suggest that ectopic DV interaction may induce expression of Djnlg in the positional cue-producing cells, and that it might be involved in stimulation of blastema formation as well as DV patterning of the body.

Amino Acid Sequence↗
PubMed2002

The body margin of the planarian Dugesia japonica: characterization by the expression of an intermediate filament gene.

We have cloned and sequenced a cDNA encoding an intermediate filament protein (IF) from the planarian Dugesia japonica named DjIFb. The deduced amino acid sequence of DjIFb has similarity to those of protostomic IFs and lamins, supporting a previous hypothesis that the protostomic IFs, including DjIFb, are evolutionarily closer to lamins than to vertebrate cytoplasmic IFs. In addition, analysis of the exon/intron organization revealed that 8 out of 10 introns of DjIFb were coincident in their position, even in the codon phase, with those of the non-neuronal IF of the snail Helix aspersa. This suggests that the Platyhelminthes are not the most primitive Bilateria but instead are evolutionarily close to the Mollusca. The DjIFb gene was expressed in particular cells, probably a kind of adhesive gland cell, which were present in the marginal region encircling the planarian body. The localization of DjIFb protein suggests that it plays an important role in the secretion of an adhesive substance. The specific expression pattern of the DjIFb gene enabled us to monitor how the body margin forms during planarian regeneration.

Amino Acid Sequence↗
PubMed2002

Uncoupling protein 2 plays an important role in nitric oxide production of lipopolysaccharide-stimulated macrophages.

The expression of uncoupling protein 2 (UCP2) was reduced in macrophages after stimulation with lipopolysaccharide (LPS). The physiological consequence and the regulatory mechanisms of the UCP2 down-regulation by LPS were investigated in a macrophage cell line, RAW264 cells. UCP2 overexpression in RAW264 cells transfected with eukaryotic expression vector containing ucp2 cDNA markedly reduced the production of intracellular reactive oxygen species. Furthermore, in the UCP2 transfectant, nitric oxide (NO) synthesis, inducible NO synthase (NOS II) protein, NOS II mRNA, and NOS II promoter activity were definitely decreased after LPS stimulation compared with those in parental RAW264 or RAW264 cells transfected with the vector alone. Reporter assays suggested that an enhancer element was located in the region of intron 2 of the UCP2 gene and that the UCP2 expression was down-regulated not by the 7.3-kb promoter region but by the 5' region of the UCP2 gene containing two introns. Deletion of intron 2 resulted in the low transcriptional activities and abolishment of the LPS-associated negative regulation. In addition, the mRNA expression of transfected UCP2 was suppressed in RAW264 cells transfected with expression vector containing UCP2 genomic DNA, but was markedly increased in cells transfected with the vector containing UCP2 intronless cDNA. These findings suggest that the LPS-stimulated signals suppress UCP2 expression by interrupting the function of intronic enhancer, leading to an up-regulation of intracellular reactive oxygen species, which activate the signal transduction cascade of NOS II expression, probably to ensure rapid and sufficient cellular responses to a microbial attack.

Animals↗
PubMed2002

Identification of a novel non-structural maintenance of chromosomes (SMC) component of the SMC5-SMC6 complex involved in DNA repair.

Structural maintenance of chromosomes (SMC) proteins play central roles in chromosome organization and dynamics. They have been classified into six subtypes, termed SMC1 to SMC6, and function as heterodimer components of large protein complexes that also include several non-SMC proteins. The SMC2-SMC4 and SMC1-SMC3 complexes are also known as condensin and cohesin, respectively, but the recently identified SMC5 and SMC6 complex is less well characterized. Here, we report that NSE1 from Saccharomyces cerevisiae encodes a novel non-SMC component of the SMC5(Yol034wp)-SMC6(Rhc18p) complex corresponding to the 2-3-MDa molecular mass. Nse1p is essential for cell proliferation and localizes primarily in the nucleus. nse1 mutants are highly sensitive to DNA-damaging treatments and exhibit abnormal cellular morphologies, suggesting aberrant mitosis as a terminal morphological phenotype. These results are consistent with the reported features of the Schizosaccharomyces pombe SMC6 gene, rad18, which is thought to be involved in recombinational DNA repair. We conclude that Nse1p and the SMC5-SMC6 heterodimer together form a high molecular mass complex that is conserved in eukaryotes and required for both DNA repair and proliferation.

Amino Acid Sequence↗