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Biomedical subjects

Shinji Hashimoto

Publications and source records attributed to Shinji Hashimoto.

11 recordsLinked to original sources
PubMed2007

Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.

Glucokinase (Gck) functions as a glucose sensor for insulin secretion, and in mice fed standard chow, haploinsufficiency of beta cell-specific Gck (Gck(+/-)) causes impaired insulin secretion to glucose, although the animals have a normal beta cell mass. When fed a high-fat (HF) diet, wild-type mice showed marked beta cell hyperplasia, whereas Gck(+/-) mice demonstrated decreased beta cell replication and insufficient beta cell hyperplasia despite showing a similar degree of insulin resistance. DNA chip analysis revealed decreased insulin receptor substrate 2 (Irs2) expression in HF diet-fed Gck(+/-) mouse islets compared with wild-type islets. Western blot analyses confirmed upregulated Irs2 expression in the islets of HF diet-fed wild-type mice compared with those fed standard chow and reduced expression in HF diet-fed Gck(+/-) mice compared with those of HF diet-fed wild-type mice. HF diet-fed Irs2(+/-) mice failed to show a sufficient increase in beta cell mass, and overexpression of Irs2 in beta cells of HF diet-fed Gck(+/-) mice partially prevented diabetes by increasing beta cell mass. These results suggest that Gck and Irs2 are critical requirements for beta cell hyperplasia to occur in response to HF diet-induced insulin resistance.

Animals↗
PubMed2006

Protonation and hydrogen-bonding state of the distal histidine in the CO complex of horseradish peroxidase as studied by ultraviolet resonance Raman spectroscopy.

Ultraviolet resonance Raman (UVRR) spectroscopy has been used to characterize the structure and hydrogen bonding state of the distal histidine (His42) in horseradish peroxidase (HRP) complexed with carbon monoxide (HRP-CO). The HRP-CO - HRP UVRR difference spectrum in D(2)O solution at pD 7.0 shows two positive peaks at 1408 and 1388 cm(-)(1), which are ascribable to medium-to-weak and strong hydrogen bonding states, respectively, of the protonated imidazolium side chain of His42 in HRP-CO. Both His42 peaks decrease in intensity with increase of pD with a midpoint of transition at pD 8.8, indicating that the pK(a) of His42 in HRP-CO is 8.8. The CO ligand exhibits two C-O stretching Raman peaks at 1932 and 1902 cm(-)(1), the latter of which diminishes at alkaline pD and is assignable to a strong hydrogen-bonded state. It is most probable that the imidazolium side chain of His42 forms a strong hydrogen bond with CO, giving a His42 peak at 1388 cm(-)(1) and a CO peak at 1902 cm(-)(1), in one conformer. The other hydrogen bonding state of His42, giving the 1408 cm(-)(1) peak, is ascribed to another conformer forming a medium-to-weak hydrogen bond with a water molecule in the distal cavity. The present finding that His42 can act as a strong proton donor to CO and decrease the CO bond order is consistent with the role of His42 as a general acid to cleave the O-O bond of hydrogen peroxide, a specific oxidizing agent, in the catalytic cycle of HRP.

Binding Sites↗
PubMed2005

Direct mating between diploid sake strains of Saccharomyces cerevisiae.

Various auxotrophic mutants of diploid heterothallic Japanese sake strains of Saccharomyces cerevisiae were utilized for selecting mating-competent diploid isolates. The auxotrophic mutants were exposed to ultraviolet (UV) irradiation and crossed with laboratory haploid tester strains carrying complementary auxotrophic markers. Zygotes were then selected on minimal medium. Sake strains exhibiting a MATa or MATalpha mating type were easily obtained at high frequency without prior sporulation, suggesting that the UV irradiation induced homozygosity at the MAT locus. Flow cytometric analysis of a hybrid showed a twofold higher DNA content than the sake diploid parent, consistent with tetraploidy. By crossing strains of opposite mating type in all possible combinations, a number of hybrids were constructed. Hybrids formed in crosses between traditional sake strains and between a natural nonhaploid isolate and traditional sake strains displayed equivalent fermentation ability without any apparent defects and produced comparable or improved sake. Isolation of mating-competent auxotrophic mutants directly from industrial yeast strains allows crossbreeding to construct polyploids suitable for industrial use without dependence on sporulation.

Alcoholic Beverages↗
PubMed2005

Effect of intraportal infusion to improve small for size graft injury in living donor adult liver transplantation.

The most important problem in the living donor adult liver transplantation (LDALT) is a small for size graft. Although a right lobe graft is used in many cases in order to avoid small for size graft, for a donor, the risk has few in left lobe graft. We evaluate the effect of an intraportal infusion treatment to the small for size graft. One hundred and twelve patients who underwent LDALT were studied. The graft weight recipient standard liver volume ratio (GV/SLV) of these patients were 50% or less. We divided the patients into following two groups; infusion group (n = 53) and control group (n = 59). For the infusion group, 16 G double lumen catheter was inserted into portal vein and nafamostat mesilate (protease inhibitor which stabilize coagulofibrinolytic state; 200 mg/day), prostaglandin E(1) (vasodilator and hepatoprotective effect; 500 microg/day) and thromboxane A(2) synthetase inhibitor (vasodilator and anticoagulant effect; 160 mg/day) were administrated continuously for 7 days. Small-for-size graft syndrome was defined as bilirubin >10 mg/dl and ascites >1000 cc on postoperative day (POD) 14. Comparison examination of a background factors and postoperative bilirubin and amount of ascites was carried out. The mean GV/SLV did not have the difference at 39.1% of infusion group, and 38.3% of control group (P = 0.58). By the control group, 15 patients (25.4%) were small-for-size graft syndrome, however, there was only two (3.8%) small-for-size graft syndrome in infusion group (P = 0.04). The bilirubin levels of infusion and control group on 7 and 14 POD were 9.9 and 7.8 vs. 9.5 and 10.5 mg/dl, respectively. The amount of ascites of infusion group on 7 and 14 POD were 870 and 430 cc, respectively. On the contrary, in control group, the amount of ascites on 7 and 14 POD were 1290 and 1070 cc, respectively. Bilirubin levels and the amount of ascites on 7 and 14 POD were lower in the patients with infusion group then those with control group. There were no differences between infusion group and control group in age, sex and Child's classification. The intraportal infusion had an effect in prevention of hyperbilirubinemia and loss in quality of excessive ascites in the patients with small for size graft. This was suggested to be what is depended on the improvement of the microcirculation insufficiency considered one of the causes of small-for-size graft syndrome.

Adult↗
PubMed2005

Isolation of auxotrophic mutants of diploid industrial yeast strains after UV mutagenesis.

Auxotrophic mutants of the yeast Saccharomyces cerevisiae are usually isolated in haploid strains because the isolation of recessive mutations in diploids is thought to be difficult due to the presence of two sets of genes. We show here that auxotrophic mutants of diploid industrial sake yeast strains were routinely obtained by a standard mutant selection procedure following UV mutagenesis. We isolated His(-), Met(-), Lys(-), Trp(-), Leu(-), Arg(-), and Ura(-) auxotrophic mutants of five sake strains, Kyokai no. 7, no. 9, no. 10, no. 701, and no. 901, by screening only 1,700 to 3,400 colonies from each treated strain. Wild-type alleles were cloned and used as markers for transformation. With HIS3 as a selectable marker, the yeast TDH3 overexpression promoter was inserted upstream of ATF1, encoding alcohol acetyltransferase, by one-step gene replacement in a his3 mutant of Kyokai no. 7. The resulting strain contained exclusively yeast DNA, making it acceptable for commercial use, and produced a larger amount of isoamyl acetate, a banana-like flavor. We argue that the generally recognized difficulty of isolating auxotrophic mutants of diploid industrial yeast strains is misleading and that genetic techniques used for haploid laboratory strains are applicable for this purpose.

Amino Acids, Essential↗
PubMed2004

alpha1-acid glycoprotein fucosylation as a marker of carcinoma progression and prognosis.

BACKGROUND: Serum alpha1-acid glycoprotein (AGP), an acute-phase protein secreted by the liver, carries alpha(1,3)-fucosylated structures on its 5 highly branched, N-linked sugar chains. METHODS: Serum AGP levels in patients with various types of malignancies (n=214 patients) were measured using an enzyme-linked immunosorbent assay with anti-AGP antibody. To investigate glycoforms that differed in their degree of branching and extent of fucosylation, serum AGP samples were analyzed by crossed affinoimmunoelectrophoresis (CAIE) with concanavalin A, and Aleuria aurantia lectin (AAL), and anti-AGP antibody. RESULTS: A significant difference (P <0.001) in serum AGP levels was observed in preoperative patients compared with levels in the healthy control group, but the levels in individual patients did not reflect their clinical status. Conversely, it was found not only that the patterns of AGP glycoforms differed widely in the patient group compared with the healthy control group, but they also changed depending on each patient's clinical status. Furthermore, AGP glycoforms seemed to be appropriate markers of disease progression and prognosis according to follow-up studies of 45 patients during prolonged preoperative and postoperative periods. CONCLUSIONS: Patients with advanced malignancies who had AGP glycoforms that contained highly fucosylated triantennary and tetraantennary sugar chains for long periods after surgery were likely to have a poor prognosis. However, patients who had AGP glycoforms without such changes were expected to have a good prognosis.

Biomarkers, Tumor↗
PubMed2002

Neurochemical and behavioural characterization of milnacipran, a serotonin and noradrenaline reuptake inhibitor in rats.

RATIONALE: The prefrontal cortex is implicated in the pathophysiology of depression, and hypoactivity of this brain area has been found in depressed patients. Reduced function of the serotonergic and noradrenergic systems is another feature of depression. OBJECTIVES: The present study was aimed at characterizing neurochemically and behaviorally the serotonin and noradrenaline reuptake inhibitor (SNRI), milnacipran, in the prefrontal cortex in comparison with tricyclic antidepressants and selective serotonin reuptake inhibitors. METHODS: Sodium-dependent monoamine uptake measurement, radioligand binding assays, microdialysis procedure, forced swimming test and conditioned fear stress test were carried out in rats. RESULTS: Milnacipran selectively inhibited sodium-dependent [(3)H]serotonin (5-hydroxytryptamine, 5-HT) and [(3)H]noradrenaline (NA) uptake into the synaptosomes from rat cerebral cortex (IC(50)=28.0 and 29.6 nM, respectively) without any affinities for various neuroreceptors. In the medial prefrontal cortex, milnacipran (10 and 30 mg/kg, PO) caused a dose-related increase in the extracellular levels of 5-HT and NA with similar potency, whereas imipramine (10 and 30 mg/kg, PO) caused a dominant increase in the output of NA compared to 5-HT. Milnacipran (30 and 60 mg/kg, PO) significantly reduced the duration of both the immobility time in the forced swimming test and the freezing time in the conditioned fear stress test in rats, which are animal behavioral models for depression and anxiety, respectively. Imipramine and maprotiline were active in the former test, but not in the latter. Fluoxetine and fluvoxamine on the other hand were more active in the conditioned fear test. CONCLUSION: These findings show that milnacipran acts as a SNRI in vitro and in vivo and may be useful for the treatment of anxiety as well as depression.

Adrenergic Uptake Inhibitors↗
PubMed2002

Changes in hydrogen bonding and environment of tryptophan residues on helix F of bacteriorhodopsin during the photocycle: a time-resolved ultraviolet resonance Raman study.

Protein structural changes during the photocycle of bacteriorhodopsin were examined by time-resolved ultraviolet resonance Raman (UVRR) spectroscopy. Most of the 244-nm UVRR difference signals of Trp were assigned to either Trp182 or Trp189 using the Trp182 --> Phe and Trp189 --> Phe mutants. The W17 mode of Trp182 shows a wavenumber downshift in the M(1) --> M(2) transition, indicating an increase in hydrogen bonding strength at the indole nitrogen. On the other hand, Trp189 shows Raman intensity increases of the W16 and W18 modes ascribable to an increased hydrophobic interaction. These observations suggest that the tilt of helix F, which ensures that reprotonation of the Schiff base is from the cytoplasmic side, occurs in the M(1) --> M(2) transition. In the M(2) --> N transition, the environment of Trp189 returns to the initial state, whereas the hydrophobic interaction of Trp182 decreases drastically. The decrease in hydrophobic interaction of Trp182 in the N state suggests an invasion of water molecules that promote the proton transfer from Asp96 to the Schiff base. Structural reorganization of the protein after the tilt of helix F may be important for efficient reprotonation of the Schiff base.

Bacteriorhodopsins↗
PubMedDate not supplied

Resected case of a double cancer, a hepatocellular carcinoma and a cholangiocellular carcinoma, and their spread to the skin.

Combined hepatocellular and cholangiocellular carcinomas are rare. Moreover, double cancer cases of hepatocellular carcinoma and cholangiocellular carcinoma are very rare. This report describes a patient with double cancer. A correct clinical diagnosis was made with successful resection, and cutaneous metastases occurred near the exit site of an abdominal drain after the resection of the tumor. The patient, a 66-year-old man with chronic hepatitis C, was admitted to our hospital because he was suspected of having primary liver cancer. Two liver masses in the anteroinferior segment were detected by using angiography, computed tomography during angiography, and computed tomography during arterioportography. These clinical findings indicated that the tumor in the right lobe was hepatocellular carcinoma. A resection of the S5 subsegmentectomy was performed. One mass was diagnosed histologically as hepatocellular carcinoma, and the other mass was diagnosed as cholangiocellular carcinoma. One year after the operation, the patient palpated a hard subcutaneous nodule 4.0 cm in diameter in the right lower abdominal wall. A subcutaneous tumor was excised, and a histological examination revealed moderately differentiated hepatocellular carcinoma. The patient is currently doing well without further recurrence of hepatocellular carcinoma or cholangiocellular carcinoma, 18 months after subsegmentectomy and six months after excision of the subcutaneous tumor.

Aged↗
PubMedDate not supplied

A localized primary sclerosing cholangitis preoperatively diagnosed as hilar cholangiocarcinoma; report of a case.

The authors report herein a case of primary sclerosing cholangitis localized to the hepatic hilum which occurred in a 67-year-old male. The direct cholangiography revealed bile duct stenosis from the common hepatic duct to bilateral hepatic ducts. We could not confirm bile duct malignancy, however, hilar cholangiocarcinoma was most suspicious. We performed right trisegmentectomy of the liver with caudate lobectomy and lymph node dissection 3 weeks after right portal embolization. Pathological findings confirmed localized primary sclerosing cholangitis. Surgical resection of the affected bile duct is most effective in localized primary sclerosing cholangitis, because the prognosis of the disease is poor and secondary carcinogenesis in primary sclerosing cholangitis has high incidence.

Aged↗