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Biomedical subjects

S Hirota

Publications and source records attributed to S Hirota.

At least 19 recordsLinked to original sources
PubMed2005

Reduction of ferricytochrome c by tyrosyltyrosylphenylalanine.

Cytochrome c (cyt c) was reduced by a tyrosine-containing peptide, tyrosyltyrosylphenylalanine (TyrTyrPhe), at pH 6.0-8.0, while tyrosinol or tyrosyltyrosine (TyrTyr) could not reduce cyt c effectively under the same condition. Cyt c was reduced at high peptide concentration, whereas the reaction did not occur effectively at low concentration. The reaction rate varied with time owing to a decrease in the TyrTyrPhe concentration and the production of tyrosine derivatives during the reaction. The initial rate constants were 2.4 x 10(-4) and 8.1 x 10(-4) s(-1) at pH 7.0 and 8.0, respectively, for the reaction with 1.0 mM TyrTyrPhe in 10 mM phosphate buffer at 15 degrees C. The reciprocal initial rate constant (1/k(int)) increased linearly against the reciprocal peptide concentration and against the linear proton concentration, whereas logk(int) decreased linearly against the root of the ionic strength. These results show that deprotonated (TyrTyrPhe)(-), presumably deprotonated at a tyrosine site, reduces cyt c by formation of an electrostatic complex. No significant difference in the reaction rate was observed between the reaction under nitrogen and oxygen atmospheres. From the matrix-assisted laser desorption ionization time-of-flight mass spectra of the reaction products, formation of a quinone and other tyrosine derivatives of the peptide was supported. These products should have been produced from a tyrosyl radical. We interpret the results that a cyt c(ox)/(TyrTyrPhe)(-)right harpoon over left harpooncyt c(red)/(TyrTyrPhe)(*) equilibrium is formed, which is usually shifted to the left. This equilibrium may shift to the right by reaction of the produced tyrosyl radical with the tyrosine sites of unreacted TyrTyrPhe peptides.

Animals↗
PubMed2005

Comparison of a combination of midazolam and diazepam and midazolam alone as oral premedication on preanesthetic and emergence condition in children.

BACKGROUND: Preanesthetic anxiety and emergence agitation are major challenges for anesthesiologists in pediatric anesthesia. Thus, midazolam has been used as premedication for children. However, midazolam alone is not effective for emergence agitation. The present study tested the effect of a combination of midazolam and diazepam on the preanesthetic condition and emergence behavior in children. METHODS: Forty-two children were allocated to one of three groups: the NoPre group received no premedication; the Mi group received midazolam 0.5 mg kg(-1) orally; and the Mi + Di group received midazolam 0.25 mg kg(-1) and diazepam 0.25 mg kg(-1) orally. When anesthesia was induced with 7% sevoflurane in 100% oxygen, qualities of mask induction and sedation were rated. Anesthesia was maintained with sevoflurane (3-5%) in 100% oxygen. During emergence from anesthesia, the score of the child's emergence behavior was rated. RESULTS: Children in the Mi and Mi + Di groups were more sedated than those in the NoPre group. A combination of midazolam and diazepam provided a better quality of mask induction, when compared with no premedication. Also, the children in the Mi + Di group were less agitated than those in the other groups during the emergence. CONCLUSION: Children in the Mi + Di group were significantly more sedated at induction of anesthesia and less agitated during emergence from anesthesia.

Adenoidectomy↗
PubMed2005

The "pulvinar sign" in a case of paraneoplastic limbic encephalitis associated with non-Hodgkin's lymphoma.

This paper reports a 59 year old woman with paraneoplastic limbic encephalitis associated with diffuse large B cell lymphoma. Her brain magnetic resonance imaging scan showed bilateral posterior thalamic hyperintensities, similar to the "pulvinar sign". Her symptoms included progressive psychiatric disturbance and resembled the initial symptoms of variant Creutzfeldt-Jakob disease (vCJD). Clinicians should consider this treatable disorder in the differential diagnosis of vCJD.

Axilla↗
PubMed2003

Ectopically expressed PDX-1 in liver initiates endocrine and exocrine pancreas differentiation but causes dysmorphogenesis.

To date, the potency of pancreatic and duodenal homeobox gene 1 (PDX-1) in inducing differentiation into insulin-producing cells has been demonstrated in some cells and tissues. In order to carry out efficient screening of somatic tissues and cells that can transdifferentiate into beta-cell-like cells in response to PDX-1, we generated CAG-CAT-PDX1 transgenic mice carrying a transgene cassette composed of the chicken beta-actin gene (CAG) promoter and a floxed stuffer DNA sequence (CAT) linked to PDX-1 cDNA. When the mice were crossed with Alb-Cre mice, which express the Cre recombinase driven by the rat albumin gene promoter, PDX-1 was expressed in more than 50% of hepatocytes and cholangiocytes. The PDX-1 (+) livers expressed a variety of endocrine hormone genes such as insulin, glucagon, somatostatin, and pancreatic polypeptide. In addition, they expressed exocrine genes such as elastase-1 and chymotrypsinogen 1B. However, the mice exhibited marked jaundice due to conjugated hyperbilirubinemia, and the liver tissue displayed abnormal lobe structures and multiple cystic lesions. Thus, the in vivo ectopic expression of PDX-1 in albumin-producing cells was able to initiate but not complete the differentiation of liver cells into pancreatic cells. The conditional PDX-1 transgenic mouse system developed in this study appeared to be useful for efficient screening of PDX-1 responsive somatic tissues and cells.

Animals↗
PubMed2003

Vasodilatory and electrophysiological actions of 8-iso-prostaglandin E2 in porcine coronary artery.

We examined the effects of several E-ring and F-ring isoprostanes on mechanical and electrophysiological activity in porcine coronary artery. Several isoprostanes evoked concentration-dependent contractions, with 8-iso-PGE2 being the most potent (-log EC50 of 6.9 +/- 0.1); this excitatory effect has been described in detail elsewhere and was not examined further here. 8-iso-PGE2 evoked dose-dependent relaxations in tissues preconstricted with the thromboxane A2-agonist U46619 (10(-6) M), with a negative log EC50 of 6.0 +/- 0.1 (n = 5). 8-iso-PGE1 and 8-iso-PGF2 beta also evoked relaxations (albeit with lower potency), whereas the other F-ring isoprostanes (8-iso-PGF1 alpha, 8-iso-PGF1 beta, and 8-iso-PGF2 alpha) were largely ineffective in this respect. The potency and efficacy of 8-iso-PGE2 in reversing tone were not dependent upon the concentration of U46619 used to preconstrict the tissues (10(-8) to 10(-6) M), indicating a lack of U46619-induced functional antagonism of these responses. 8-iso-PGE2 was able to completely relax tissues that had been denuded of endothelium (as indicated by loss of responsiveness to bradykinin). 8-iso-PGE2-evoked relaxations were markedly reduced by elevating the K+ equilibrium potential using 30 mM KCl and abolished by 60 mM KCl; they were also sensitive to charybdotoxin (10(-7) M) but not to 4-aminopyridine (1 mM). 8-iso-PGE2 also caused membrane hyperpolarization and augmentation of outward K+ current. We conclude that 8-iso-prostaglandin E2 acts directly on the smooth muscle to increase K+ conductance, leading to membrane hyperpolarization and vasodilation.

Animals↗
PubMed2003

The shape parameter of liposomes and DNA-lipid complexes determined by viscometry utilizing small sample volumes.

A minicapillary viscometer utilizing <0.5 ml of sample at a volume fraction of <0.1% is described. The calculated a/b of DPPC/DPPG multilamellar liposome was 1.14 as prolate ellipsoids and a/b of dioleoylpropyltrimethyl ammonium methylsulfate-DNA complex at a charge ratio of 4:1 (+/-) was 3.7 as prolate ellipsoids or 4.9 as oblate ellipsoids. The deviation of shape from perfect sphere is thus expressed quantitatively in more than two significant figures. In these measurement, the necessary amount of DNA is <0.5 mg.

Capillary Action↗
PubMed2002

Polyclonal nature of diffuse proliferation of interstitial cells of Cajal in patients with familial and multiple gastrointestinal stromal tumours.

BACKGROUND: Diffuse proliferation of interstitial cells of Cajal (ICCs) in the myenteric plexus layer of the intestine has been described in patients with familial and multiple gastrointestinal stromal tumours (GISTs). However, it is not fully understood whether proliferation is polyclonal or monoclonal. AIMS: To evaluate the clonal nature of diffuse ICC proliferation in familial and multiple GIST cases, we carried out clonal analysis using inactivation at the human androgen receptor (HUMARA) locus. MATERIALS AND METHODS: Diffuse ICC proliferation tissues from three female patients were microdissected using a laser capture microdissection (LCM) system. Normal intestinal mucosal tissues were also microdissected for polyclonal controls and GIST tissues for monoclonal controls from the same patients, and genomic DNA was extracted. After digestion by restriction enzyme HhaI, the HUMARA locus was amplified by a fluorescent polymerase chain reaction (PCR) procedure and the PCR products were analysed. RESULTS: One case was uninformative because it was homozygous at the HUMARA locus. In the two other cases, PCR products from the diffuse ICC proliferation showed two alleles as well as those from normal intestinal mucosal tissues, indicating that ICC proliferation was polyclonal. In contrast, PCR products from associated GIST tissues showed only one allele, indicating that GISTs were monoclonal. CONCLUSION: The results suggested that diffuse ICC proliferation in familial and multiple GIST cases was non-neoplastic hyperplasia.

Cell Division↗
PubMed2001

Spectroscopic observation of intermediates formed during the oxidative half-reaction of copper/topa quinone-containing phenylethylamine oxidase.

The catalytic reaction of copper/topa quinone (TPQ) containing amine oxidase consists of the initial, well-characterized, reductive half-reaction and the following, less studied, oxidative half-reaction. We have analyzed the oxidative half-reaction catalyzed by phenylethylamine oxidase from Arthrobacter globiformis (AGAO) by rapid-scan stopped-flow measurements. Upon addition of dioxygen to the substrate-reduced AGAO at pH 8.2, the absorption bands derived from the semiquinone (TPQ(sq)) and aminoresorcinol forms of the TPQ cofactor disappeared within the dead time (<1 ms) of the measurements, indicating that the reaction of the substrate-reduced enzyme with dioxygen is very rapid. Concomitantly, an early intermediate exhibiting an absorption band at about 410 nm was formed, which then decayed with a rate constant of 390 +/- 50 s(-1). This intermediate was detected more prominently in the reaction in D2O buffer (pD 8.1) and was assigned to a Cu(II)-peroxy species. The assignment was based on the observation that addition of H2O2 to the substrate-reduced AGAO under anaerobic conditions led to the formation of a new band at about 415 nm, accompanied by partial quenching of absorption bands derived from TPQ(sq). Other intermediates exhibiting absorption bands at about 310 and 340 nm were also observed in the oxidative half-reaction. Kinetics of the disappearance of these latter bands did not correspond with that of the Cu(II)-peroxy band at 410 nm but did well with that of the increase of the 480 nm absorption band due to the reoxidized TPQ. Rapid increase of the absorption in the 320-370 nm region was also observed for the reaction of the substrate-reduced, Ni-substituted enzyme with dioxygen. On the basis of these results, a possible mechanism is proposed for the oxidative half-reaction of the bacterial copper amine oxidase.

Amine Oxidase (Copper-Containing)↗
PubMed2001

Localized aggressive non-Hodgkin's lymphoma of the nasal cavity: a survey by the Japan Lymphoma Radiation Therapy Group.

PURPOSE: To clarify the role of radiotherapy and chemotherapy in the treatment of patients with localized aggressive non-Hodgkin's lymphomas (NHL) originating in the nasal cavity. METHODS AND MATERIALS: The survey, administered at 25 Japanese institutes in 1998, enabled us to collect the clinical data for 787 patients with localized aggressive NHL who were treated between 1988 and 1992. RESULTS: There were 42 patients (5%) with nasal lymphomas. Twelve of these patients received radiotherapy alone, and 30 were treated with a combination of radiotherapy and chemotherapy. The median radiation dose was 47 Gy (22-66). Twelve patients were reviewed histopathologically according to REAL (Revised European-American Classification of Lymphoid neoplasms) classification. T-cell or natural killer (NK) cell lymphomas were detected in 9 patients (75%), and diffuse large B-cell lymphomas in 3 (25%). The 5-year overall and disease-free survival (DFS) rates of all patients were 57% and 59%, respectively. The 5-year DFS rate for the 30 patients treated with the combined therapy was 64% and that for the 12 patients treated with radiotherapy alone was 46% (p = 0.021). For the 34 patients with stage-modified International Prognostic Index (m-IPI) 0-1, the 5-year DFS rates of those treated with the combined therapy and radiotherapy alone were 68% and 45%, respectively (p = 0.020), but there was no difference in DFS rate among the two groups of patients with m-IPI 2-3. The 5-year local control rates of the patients who received >46 Gy (n = 22) and < or =46 Gy (n = 20) were 95% and 76% (p = 0.087), respectively. There was no significant difference among the 5-year DFS rates (62% vs. 67%) and local control rates (87% vs. 100%) of the patients with T-cell or NK-cell lymphoma and diffuse large B-cell lymphoma. CONCLUSIONS: Patients with nasal lymphomas (m-IPI 0-1) should be treated with combined therapy. For the patients with high risk (m-IPI 2-3), the effectiveness of combined therapy was not clarified because of the small number of the patients. A high radiation dose >46 Gy may need to be used to achieve good local control.

Adolescent↗
PubMed2001

Dosimetric predictors of radiation esophagitis in patients treated for non-small-cell lung cancer with carboplatin/paclitaxel/radiotherapy.

PURPOSE: To establish dosimetric predictors of radiation esophagitis (RE) in patients treated with a combination of carboplatin, paclitaxel, and radiotherapy. METHODS AND MATERIALS: Three-dimensional radiotherapy plans of 26 patients with non-small-cell lung cancer who received 50-60 Gy of radiotherapy concurrently with weekly administration of carboplatin (AUC 2) and paclitaxel (40-45 mg/m(2)) were reviewed in conjunction with RE. The factors analyzed included the following: percentages of organ volumes receiving >40 Gy (V40), >45 Gy (V45), >50 Gy (V50), and >55 Gy (V55); the length of esophagus (total circumference) treated with >40 Gy (LETT40), >45 Gy (LETT45), >50 Gy (LETT50), and >55 Gy (LETT55); the maximum dose in the esophagus (Dmax); and the mean dose in the esophagus (Dmean). Data were obtained on the basis of superposition algorithm. RESULTS: All factors except Dmax showed statistical correlation with RE. Good correlations were shown between RE and LETT45 (rho = 0.714) and V45 (rho = 0.686). CONCLUSIONS: LETT45 and V45 appear to be useful dosimetric predictors of RE. It is also suggested that Dmax does not predict RE.

Adult↗
PubMed2001

Cathelicidin family of antibacterial peptides CAP18 and CAP11 inhibit the expression of TNF-alpha by blocking the binding of LPS to CD14(+) cells.

Mammalian myeloid and epithelial cells express several kinds of antibacterial peptides (alpha-/beta-defensins and cathelicidins) that contribute to the innate host defense by killing invading micro-organisms. In this study we evaluated the LPS-neutralizing activities of cathelicidin peptides human CAP18 (cationic antibacterial proteins of 18 kDa) and guinea pig CAP11 using the CD14(+) murine macrophage cell line RAW264.7 and the murine endotoxin shock model. Flow cytometric analysis revealed that CAP18 and CAP11 inhibited the binding of FITC-conjugated LPS to RAW264.7 cells. Likewise, Northern and Western blot analyses indicated that CAP18 and CAP11 suppressed LPS-induced TNF-alpha mRNA and protein expression by RAW264.7 cells. Interestingly, CAP18 and CAP11 possessed LPS-binding activities, and they strongly suppressed the interaction of LPS with LPS binding protein that mediates the transport of LPS to CD14 to facilitate the activation of CD14(+) cells by LPS. Moreover, when CAP18 and CAP11 were preincubated with RAW264.7 cells, they bound to the cell surface CD14 and inhibited the binding of FITC-LPS to the cells. Furthermore, in the murine endotoxin shock model, CAP18 or CAP11 administration inhibited the binding of LPS to CD14(+) cells (peritoneal macrophages) and suppressed LPS-induced TNF-alpha expression by these cells. Together these observations indicate that cathelicidin peptides CAP18 and CAP11 probably exert protective actions against endotoxin shock by blocking the binding of LPS to CD14(+) cells, thereby suppressing the production of cytokines by these cells via their potent binding activities for LPS and CD14.

Acute-Phase Proteins↗
PubMed2001

Differentiation-associated Na+-dependent inorganic phosphate cotransporter (DNPI) is a vesicular glutamate transporter in endocrine glutamatergic systems.

Vesicular glutamate transporter is present in neuronal synaptic vesicles and endocrine synaptic-like microvesicles and is responsible for vesicular storage of L-glutamate. A brain-specific Na(+)-dependent inorganic phosphate transporter (BNPI) functions as a vesicular glutamate transporter in synaptic vesicles, and the expression of this BNPI defines the glutamatergic phenotype in the central nervous system (Bellocchio, E. E., Reimer, R. J., Fremeau, R. T., Jr., and Edwards, R. H. (2000) Science 289, 957-960; Takamori, S., Rhee, J. S., Rosenmund, C., and Jahn, R. (2000) Nature 407, 189-194). However, since not all glutamatergic neurons contain BNPI, an additional transporter(s) responsible for vesicular glutamate uptake has been postulated. Here we report that differentiation-associated Na(+)-dependent inorganic phosphate cotransporter (DNPI), an isoform of BNPI (Aihara, Y., Mashima, H., Onda, H., Hisano, S., Kasuya, H., Hori, T., Yamada, S., Tomura, H., Yamada, Y., Inoue, I., Kojima, I., and Takeda, J. (2000) J. Neurochem. 74, 2622-2625), also transports L-glutamate at the expense of an electrochemical gradient of protons established by the vacuolar proton pump when expressed in COS7 cells. Molecular, biological, and immunohistochemical studies have indicated that besides its presence in neuronal cells DNPI is preferentially expressed in mammalian pinealocytes, alphaTC6 cells, clonal pancreatic alpha cells, and alpha cells of Langerhans islets, these cells being proven to secrete L-glutamate through Ca(2+)-dependent regulated exocytosis followed by its vesicular storage. Pancreatic polypeptide-secreting F cells of Langerhans islets also expressed DNPI. These results constitute evidence that DNPI functions as another vesicular transporter in glutamatergic endocrine cells as well as in neurons.

Adenosine Triphosphate↗
PubMed2001

A loss-of-function mutation of c-kit results in depletion of mast cells and interstitial cells of Cajal, while its gain-of-function mutation results in their oncogenesis.

Loss-of-function mutations of the c-kit receptor tyrosine kinase (KIT) result in depletion of mast cells and interstitial cells of Cajal (ICCs). In contrast, gain-of-function mutations of KIT induce neoplasms of mast cells and ICCs. In humans, the sites of mutations are different between mast cell neoplasms and those of ICCs. The former were found in the juxtamembrane domain between the transmembrane and tyrosine kinase domains, and the latter in the tyrosine kinase domain. Moreover, the mechanism of constitutive activation is different. Point mutations and/or deletions in the juxtamembrane domain induced the KIT dimerization, and the dimerized KIT was activated. A point mutation at the particular aspartic acid in the tyrosine kinase domain induced spontaneous activation without forming dimers. Mutations of the c-kit gene are a good model for understanding the relationship between mutations and diseases in both humans and mice.

Animals↗
PubMed2001

Carbon monoxide complex of cytochrome b(5) at acidic pH.

CO complex of cyt b(5) generated at acidic pH is investigated by absorption, resonance Raman (RR), and far UV CD measurements. The Soret maximum wavelength blue-shifted to 420 nm with other absorption bands observed around 540 and 570 nm for reduced cyt b(5) upon interaction with CO at acidic pH (pH 3.1-3.5). Under this condition, the iron-carbon stretching RR band was observed at 529 cm(-1) (520 cm(-1) for C(18)O), which indicated formation of a heme&bond;CO adduct with a histidine as an axial ligand. Heme dissociated from the reduced cyt b(5) protein at pH approximately 3.5, whereas its rate decreased under CO atmosphere compared with N(2) atmosphere, due to formation of a heme&bond;CO adduct with a histidine as an axial ligand.

Carbon Monoxide↗