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Shin Mizutani

Publications and source records attributed to Shin Mizutani.

14 recordsLinked to original sources
PubMed2007

[A case of stage IV advanced gastric cancer responding to TS-1/CDDP neoadjuvant chemotherapy which leads to a pathological complete response].

A 72-year-old male with advanced gastric cancer (cT3N2M0H0P0CY1, cStage IV) was treated with TS-1/CDDP as neoadjuvant chemotherapy. TS-1 (60 mg/m(2)/day) was orally administered for 3 weeks followed by 2 drug free weeks as a course, and CDDP (60 mg/m(2)) was administered by intravenous drip on day 8. After the fourth course,a significant tumor reduction was obtained. Total gastrectomy, splenectomy, and D 2 type nodal dissection were performed. The histological diagnosis revealed complete disappearance of cancer cells in the stomach and all of the lymph nodes, which is a so-called pathological complete response. The patient has now been in good health without a recurrence for 24 months after surgery. This case suggests that neoadjuvant chemotherapy with TS-1/CDDP is a potential regimen for advanced gastric cancer.

Adenocarcinoma↗
PubMed2006

Unresectable gastric cancer with multiple liver metastases effectively treated with combined paclitaxel and doxifluridine chemotherapy.

We report a 72-year-old man who was diagnosed by gastroscopy as having a type III poorly differentiated adenocarcinoma in the lesser curvature, with the longest diameter being 10 cm. An abdominal computed tomography (CT) scan revealed multiple liver metastases, thickening of the gastric wall, and an enlarged paraaortic lymph node. The serum carcinoembryonic antigen (CEA) level was 60 ng/ml and the carbohydrate antigen (CA) 19-9 level was 1355 U/ml. The patient received combined chemotherapy with doxifluridine (800 mg/body per day) and paclitaxel (one course comprised three weekly infusions at a dose of 70 mg/m(2) followed by 1-week rest). After the completion of three courses, the patient achieved a complete response (CR), with complete disappearance of the primary tumor, the metastatic foci in the liver, and the enlarged abdominal lymph nodes; as well, the tumor markers were normalized. Adverse effects included only mild anorexia that was limited to grade 1. He maintained a CR for 1 year and 2 months. Combination chemotherapy with paclitaxel and doxifluridine can be an effective treatment for unresectable advanced gastric carcinoma.

Aged↗
PubMed2006

A subset of p23 localized on secretory granules in pancreatic beta-cells.

Proteins on the membrane of secretory granules (SGs) involved in their biogenesis and exocytosis are poorly characterized compared with those of synaptic vesicle in neurons. Thus the secretory granule membrane was prepared from a mouse pancreatic beta-cell line MIN6 by subcellular fractionation, and protein constituents were analyzed by microscale two-dimensional liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Using this proteomics approach, one of the p24 family proteins, p23, was unexpectedly found in the granule fraction, although p24 proteins are generally regarded as functioning in the early secretory pathways between the endoplasmic reticulum and the Golgi apparatus. We further showed that p23 is expressed at high levels in endocrine cells. Furthermore, immunocytochemical analyses of pancreatic beta-cells at the light and electron microscopic levels demonstrated that a significant amount of p23 is localized on the insulin granule membrane, although it is most intensely concentrated at the cis-Golgi compartment as previously shown in non-endocrine cells. These findings suggest that a fraction of p23 enters post-Golgi compartments and may function in the biogenesis and/or quality control of SGs.

Animals↗
PubMed2006

Chromosome 2 locus Nidd5 has a potent effect on adiposity in the TSOD mouse.

We previously reported a quantitative trait locus for body weight, non-insulin-dependent diabetes 5 (Nidd5), on Chromosome 2 in the TSOD (Tsumura, Suzuki, Obese Diabetes) mouse, a model of polygenic obese type 2 diabetes. To find the gene responsible for a specific component of the pathogenesis, we used a marker-assisted selection protocol to produce congenic strains. These mice are designed to carry a control BALB/cA-derived genomic interval and a TSOD background to look for loss of phenotype. One of the strains with the widest congenic interval, D2Mit297-D2Mit304, showed reductions in both body weight and adiposity compared with TSOD mice. The phenotypic analyses of other congenic strains further narrowed the locus in a 9.4-Mb interval between D2Mit433 and D2Mit91, around which numerous loci for body weight and adiposity have been mapped previously. Although the locus showed a relatively modest effect on body weight, it had a major influence on fat mass that explains approximately 60% of the difference in the adipose index between parental TSOD and BALB/cA mice. Furthermore, the congenic strain with a minimal BALB/cA-derived region showed significantly smaller cell sizes of white and brown adipocytes compared with the control littermates. However, the locus did not primarily affect food consumption, general activity, or rectal temperature after cold exposure, although there are clear differences in these traits between the parental strains. The present work physically delineates the major locus for adiposity in the TSOD mouse.

Adipose Tissue↗
PubMed2006

[Combined chemotherapy with weekly Paclitaxel and doxifluridine for advanced and recurrent gastric cancers].

We conducted combined therapy of weekly paclitaxel and doxifluridine (5'-DFUR) for 23 cases of advanced and recurrent gastric carcinomas to investigate their efficacy and safety. Subjects included 7 unresectable cases, 5 noncurative resection cases, and 11 recurrent cases. Twenty of the 23 subjects had a history of prior treatment with another anticancer drug. The treatment regime consisted of one course comprising 70 mg/m(2)of paclitaxel weekly for three consecutive weeks followed by one week rest, combined with 800 mg/day of 5'-DFUR orally. Results revealed a response rate of 17.6% (3/17), with 2 cases of CR, 1 case of PR, 10 cases of NC, and 4 cases of PD. One of the CR cases was an unresectable case involving a primary tumor, liver metastasis, and abdominal lymph node metastasis, while the other was a recurrent case involving abdominal lymph node metastasis. The median survival period was 387 days. The one-and two-year survival rates were 52% and 24%, respectively. In terms of adverse effects, there were only single cases of grade 3 leukopenia and grade 3 neutropenia, with no cases of grade 4 hemotoxicity. Both patients could be treated as outpatients. Combination therapy of weekly paclitaxel and 5'-DFUR can be an effective and safe therapy for advanced and recurrent gastric carcinomas.

Adult↗
PubMed2005

Granuphilin molecularly docks insulin granules to the fusion machinery.

The Rab27a effector granuphilin is specifically localized on insulin granules and is involved in their exocytosis. Here we show that the number of insulin granules morphologically docked to the plasma membrane is markedly reduced in granuphilin-deficient beta cells. Surprisingly, despite the docking defect, the exocytosis of insulin granules in response to a physiological glucose stimulus is significantly augmented, which results in increased glucose tolerance in granuphilin-null mice. The enhanced secretion in mutant beta cells is correlated with a decrease in the formation of the fusion-incompetent syntaxin-1a-Munc18-1 complex, with which granuphilin normally interacts. Furthermore, in contrast to wild-type granuphilin, its mutant that is defective in binding to syntaxin-1a fails to restore granule docking or the protein level of syntaxin-1a in granuphilin-null beta cells. Thus, granuphilin not only is essential for the docking of insulin granules but simultaneously imposes a fusion constraint on them through an interaction with the syntaxin-1a fusion machinery. These findings provide a novel paradigm for the docking machinery in regulated exocytosis.

Adenoviridae↗
PubMed2005

Rab27a mediates the tight docking of insulin granules onto the plasma membrane during glucose stimulation.

The monomeric small GTPase Rab27a is specifically localized on both secretory granules and lysosome-related organelles. Although natural mutations of the Rab27a gene in human Griscelli syndrome and in ashen mice cause partial albinism and immunodeficiency reflecting the dysfunction of lysosome-related organelles, phenotypes resulting from the defective exocytosis of secretory granules have not been reported. To explore the roles of Rab27a in secretory granules, we analyzed insulin secretion profiles in ashen mice. Ashen mice showed glucose intolerance after a glucose load without signs of insulin resistance in peripheral tissues or insulin deficiency in the pancreas. Insulin secretion from isolated islets was decreased specifically in response to high glucose concentrations but not other nonphysiological secretagogues such as high K+ concentrations, forskolin, or phorbol ester. Neither the intracellular Ca2+ concentration nor the dynamics of fusion pore opening after glucose stimulation were altered. There were, however, marked reductions in the exocytosis from insulin granules predocked on the plasma membrane and in the replenishment of docked granules during glucose stimulation. These results provide the first genetic evidence to our knowledge for the role of Rab27a in the exocytosis of secretory granules and suggest that the Rab27a/effector system mediates glucose-specific signals for the exocytosis of insulin granules in pancreatic beta cells.

Albinism↗
PubMed2004

Deterministic stochastic resonance in a Rössler oscillator.

We discuss the characteristics of stochastic resonancelike behavior observed in a deterministic system. If a periodically forced Rössler oscillator strays from the phase locking state, it exhibits the intermittent behavior known as phase slips. When the periodic force is modulated by a weak signal, the phase slips synchronize with the weak signal statistically. We numerically demonstrate, in terms of interslip intervals and signal to noise ratio, that the maximum synchronization can be achieved with the optimum intensity of chaotic fluctuations. It is shown that the stochastic resonancelike behavior can be observed regardless of the choice of parameters. The frequency dependence of the signal indicates that there is an optimum frequency for the maximum resonance. The phase slip rate is derived based on the fact that the phase slips are caused by a boundary crisis caused by an unstable-unstable pair bifurcation. The interslip distributions obtained from the derived slip rate and the approximation theory of the time-dependent Poisson process agree with those obtained by numerical simulations. In addition, the maximum enhancement of a weak signal is shown to be achieved by adjusting the chaotic fluctuations even if a signal becomes mixed with noise.

Journal Article↗
PubMed2004

Noise-induced enhancement of fluctuation and spurious synchronization in uncoupled type-I intermittent chaotic systems.

We study the dynamics of a pair of two uncoupled identical type-I intermittent chaotic systems driven by common random forcing. We first observe that the degree of the fluctuation of the local expansion rate of orbits to perturbations of a single system as a function of the noise intensity shows a convex curve and takes its maximum value at a certain noise intensity, whereas the Liapunov exponent itself monotonically increases in this range. Furthermore, it is numerically demonstrated that this nontrivial enhancement of fluctuation causes that two orbits with different initial conditions may synchronize each other after a finite interval of time. As pointed out by Pikovsky [Phys. Lett. A 165, 33 (1992)], since the Liapunov exponent of the present system is positive, the synchronization that we observed is a numerical artifact due to the finite precision of calculations. The spurious noise-induced synchronization in an ensemble of uncoupled type-I intermittent chaotic systems are numerically characterized and the relations between these features and the fluctuation properties of the local expansion rate are also discussed.

Journal Article↗
PubMed2003

The roles of Rab27 and its effectors in the regulated secretory pathways.

Regulated secretory pathways are highly developed in multicellular organisms as a means of intercellular communication. Each of these pathways harbors unique store organelles, such as granules in endocrine and exocrine tissues and melanosomes in melanocytes. It has recently been shown that the monomeric GTPase Rab27 subfamily regulates the exocytosis of these cell-specific store organelles. Furthermore, genetic alterations of Rab27a cause Griscelli syndrome in humans that manifests as pigmentary dilution of the skin and the hair and variable immunodeficiency due to defects in the transport of melanosomes in melanocytes and lytic granules in cytotoxic T-lymphocytes. Rab27 acts through organelle-specific effector proteins, such as granuphilin in pancreatic beta cells and melanophilin in melanocytes. The Rab27 and effector complex then interacts with proteins that are essential for membrane transport and fusion, such as syntaxin 1a and Munc18-1 for granuphilin and myosin Va for melanophilin. Genome information suggests that other putative Rab27 effector proteins, tentatively termed as exophilins or Slp/Slac2, are predicted to exist because these proteins share the conserved N-terminal Rab27-binding domain and show Rab27-binding activity in vitro or when overexpressed in cell lines. These findings suggest that the Rab27 subfamily regulates various exocytotic pathways using multiple organelle-specific effector proteins.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Parathyroid hormone-related protein induces insulin expression through activation of MAP kinase-specific phosphatase-1 that dephosphorylates c-Jun NH2-terminal kinase in pancreatic beta-cells.

Parathyroid hormone-related protein (PTHrP) increases the content and mRNA level of insulin in a mouse beta-cell line, MIN6, and primary-cultured mouse islets. We examined the mechanism of PTHrP-induced insulin expression. The PTHrP effect was markedly augmented by SB203580, a mitogen-activated protein (MAP) kinase inhibitor, and SB203580 itself increased insulin expression extensively, even without PTHrP. Because SB203580 inhibits both p38 and c-jun NH(2)-terminal kinases (JNKs), we investigated the JNK-specific inhibitor SP600125. SP600125 also increased insulin content and its mRNA level. PTHrP induced dephosphorylation of JNK1/2, and PTHrP-induced insulin expression was blocked by a dominant-negative type JNK-APF. We suspected that dual specificity MAP kinase phosphatases (MKPs) may be involved in the PTHrP-induced insulin expression by inactivating JNK1/2. MIN6 cells contained at least five MKPs, among which only MKP-1 was inducible by PTHrP. PTHrP-induced insulin expression was blocked by the MKP-1 expression inhibitor Ro-31-8220, indicating that the PTHrP effect is mediated by MKP-1. Indeed, adenoviral MKP-1 expression increased insulin expression by decreasing a phosphorylation form of JNKs and a resulting phosphorylated form of c-jun in MIN6 cells. The phosphorylated form of c-jun is known to repress cAMP-dependent insulin gene promoter activity. Thus, MKP-1 controls the insulin expression by downregulating a JNK/c-jun pathway.

Animals↗
PubMed2002

Anti-(Raf-1) RNA aptamers that inhibit Ras-induced Raf-1 activation.

RNA aptamers with affinity for the Ras-binding domain (RBD) of Raf-1 were isolated from a degenerate pool by in vitro selection. These aptamers efficiently inhibited the Ras interaction with the Raf-1 RBD, and also inhibited Ras-induced Raf-1 activation in a cell-free system. The RNA aptamer with the most potent inhibitory effect specifically inhibited the Ras-Raf-1 interaction and had no affinity for the RBD of the RGL protein, a homolog of the Ral GDP dissociation stimulator. Although the aptamer was capable of binding to the B-Raf RBD, the RNA did not inhibit the interaction between Ras and the B-Raf RBD. Enzymatic and chemical probing experiments indicated that the aptamer was folded into a pseudoknot structure, and some loop regions of the pseudoknot were located at the binding interface for the Raf-1 RBD.

Base Sequence↗
PubMed2001

Dynamical origin of deterministic stochastic resonance.

We numerically demonstrate stochastic-resonance-like behavior in a deterministic chaotic oscillator system, using a modified Rössler system driven by a sinusoidal external force: intermittent 2 pi phase slips between the system and the external force synchronize with a periodic input signal that weakly modulates the external force in an appropriate parameter range. We show that the dynamical mechanism of this stochastic-resonance-like behavior is explained by a boundary crisis that depends on two bifurcation parameters.

Journal Article↗