Biomedical subjects

T Oguchi

Publications and source records attributed to T Oguchi.

At least 37 records · Page 2Linked to original sources

PubMed2000

Pollution regimes and variability in river water quality across the Humber catchment: interrogation and mapping of an extensive and highly heterogeneous spatial dataset

Water quality inter-relationships based on an extensive Environment Agency database are used to identify seven key types of clean and polluted riverine environments within the Humber catchment. These types were selected on the basis of linear separations between average concentrations of ammonium, chloride, dissolved nickel and chromium and acid-available particulate nickel and chromium. However, a more detailed analysis of determinand and flow relationships at each type locality revealed complex patterns due to the highly variable nature of pollutant sources at the local scale. The information presented contrasts systems at a larger scale, where simpler integrated features are observed, and which can be represented by two-component mixing models. Scale and hydrology seem to be important features in determining the simplicity or complexity of determinand inter-relationships, and the implications of these findings are discussed.

Journal Article↗

PubMed2000

Effect of water-soluble carriers on dissolution characteristics of nifedipine solid dispersions.

Solid dispersions of nifedipine (NP) with polyethylene glycols (PEG4000 and PEG6000), hydroxypropyl-beta-cyclodextrin (HP beta CD), and poloxamer 407 (PXM 407) in four mixing ratios were prepared by melting, solvent, and kneading methods in order to improve the dissolution of NP. The enhancement of the dissolution rate and the time for 80% NP dissolution T80% depended on the mixing ratio and the preparation method. The highest dissolution rate and the T80% as short as 15 min were obtained from PXM 407 solid dispersion prepared by the melting method at the mixing ratio of 1:10. The X-ray diffraction (XRD) patterns of solid dispersions at higher proportions of carriers demonstrated consistent with the results from differential scanning calorimetric (DSC) thermograms that NP existed in the amorphous state. The wettability and solubility were markedly improved in the PXM 407 system. The presence of intermolecular hydrogen bonding between NP and PEGs and between HP beta CD and PXM 407 was shown by infrared (IR) spectroscopy.

Calcium Channel Blockers↗

PubMed2000

Water vapor adsorption properties of amorphous cefditoren pivoxil evaluated by adsorption isotherms and microcalorimetry.

Water vapor adsorption of ground cefditoren pivoxil was studied. The amount of water adsorbed increased with a decrease in the crystallinity of cefditoren pivoxil. It was found from the microcalorimetric measurements that the differential heat of water vapor adsorption at 1.5% adsorbed water increased with decreasing crystallinity of cefditoren pivoxil, suggesting that hygroscopicity of cefditoren pivoxil was enhanced by grinding. These results indicated that hydrophilic adsorption sites in cefditoren pivoxil increased through the grinding process. The results of infrared (IR) spectra examination suggested that the increment of hydrophilic adsorption sites through the grinding process resulted from the change of the environment of the carbonyl groups in two esters and amide.

Anti-Bacterial Agents↗

PubMed2000

An improved integration replacement/disruption method for mutagenesis of yeast essential genes.

We improved the integration replacement/disruption method (Shortle, D., Novic, P., and Botstein, D. Proc. Natl. Acad. Sci. USA 81: 4889-4893, 1984) for isolating mutants in any of essential genes of the yeast Saccharomyces cerevisiae by integrating mutagenized DNA into the wild type gene of interest. We adopted this method to isolate temperature-sensitive mutants of the MPC1 gene encoding the YLL031C ORF. To facilitate integration of the mutagenic plasmid at a site near the 5' end of the ORF, a BamHI site was created at 300 bp downstream of the 5' end of the truncated ORF to be mutagenized. The MPC1 gene was disrupted in the wild type haploid strain by integrating a 5'-truncated derivative of the gene with mutations induced by in vitro mutagenesis. Transformants thus obtained were subjected for diagnosis of conditional lethality by replica-plating onto an appropriate selection medium to detect mutants. A primary mutant isolated by this method reverted in a high frequency due to a tandem repeat created by mutagenic integration. We deviced a method to obtain a stable temperature-sensitive strain by disrupting the tandem duplication. Two stable temperature-sensitive mutants thus obtained were found to be remedial either with 1 M sorbitol or with 0.1 M Mg2+ and to be sensitive to local anestheticum, tetracaine, at 25 degrees C.

Cell Division↗

PubMed2000

Usefulness of PCR in situ hybridization as a technique for morphological detection of human papillomavirus in uterine cervical neoplasia.

This study was designed in order to devise fitting conditions in polymerase chain reaction (PCR)-in situ hybridization (ISH) for observing human papillomavirus (HPV) infection morphologically in uterine cervical neoplasias and to compare the detection rates of HPV by PCR-ISH and solution phase PCR (S-PCR) as well as fluorescence ISH (FISH). Tissues were obtained from 23 patients with cervical intraepithelial neoplasia 3, who visited our hospital between 1994 and 1997. To detect HPV-16, a HPVpF forward primer and a HPVp 16 reverse primer were used. Compared with the traditional methods, the PCR-ISH technique performed in this study was contrived as follows. To prevent detachment, the specimens were attached to silane-coated slides at 90 degrees C and successively left at room temperature for 36 hours. In proteopepsis, pepsin was used. PCR products were fixed with 4% paraformaldehyde. PCR-ISH, S-PCR, and FISH showed HPV-16 positivity in 52.2%, 56.5% and 21.7%, respectively. The positive rate of HPV-16 detected by PCR-ISH as well as S-PCR was significantly higher than that by FISH (p<0.01, respectively). There was no significant difference between the positive rates of HPV-16 detected by PCR-ISH and S-PCR. HPV-16 was detected by S-PCR in all 12 specimens in which HPV-16 expression was judged as positive using PCR-ISH. Similarly, HPV-16 was found by PCR-ISH in all five specimens in which HPV-16 expression was regarded as positive using FISH. While the FISH technique detected HPV-16 signals only in the superficial and middle layers of squamous cells, the PCR-ISH technique demonstrated them in all the layers including the parabasal and basal layers. The PCR-ISH technique contrived in this study has a high sensitivity to HPV-16 equal to that of S-PCR. The difference in detection rate and distribution of HPV DNA between PCR-ISH and FISH might suggest that HPV does not infect the superficial layer but rather the parabasal layer.

Adult↗

PubMed1999

Physicochemical Properties of Ursodeoxycholic Acid Dispersed in Controlled Pore Glass.

The objective of this study was to reduce the crystallinity of ursodeoxycholic acid (UDCA) by solid dispersion with controlled pore glass (CPG). To evaluate the effect of pore diameter and pore volume of CPG on the crystalline properties of UDCA, we used powder X-ray diffractometry (PXRD) and differential scanning calorimetry (DSC). PXRD patterns and the DSC data indicated the presence of UDCA in a crystalline state in the physical mixtures. It was found that amorphous UDCA could be formed via solid dispersion with CPG obtained by a solvent method. The DSC thermograms of solid dispersions showed that there were two states of UDCA, amorphous and crystalline. The amount of crystalline fraction in the solid dispersions depended on the pore size, pore volume, and the specific surface area of CPG. When UDCA was mixed with different pore diameters of CPG, it was found that UDCA molecules preferentially interacted with pores of smaller size. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Hydroxyl radical formation during inhalation anesthesia in the reperfused working rat heart.

PURPOSE: To determine whether isoflurane, sevoflurane and halothane influenced hydroxyl radical production in the ischemic rat heart. METHODS: Twenty-four male Wistar rats were divided into four groups; control (C), isoflurane 1.4% (I), sevoflurane 2.5% (S) and halothane 1% (H). The hearts were perfused with modified Krebs-Henseleit bicarbonate buffer by a working heart model for 10 min. Then, whole heart ischemia was induced by severely restricting coronary perfusion for 15 min. Reperfusion of the hearts after this ischemic period lasted for 20 min. The coronary effluent was collected before and during ischemia and at 1, 5, 10, 20 min after reperfusion. At the end of reperfusion, hearts were removed and prepared for measurement. Hydroxyl radicals were identified by their reaction with salicylic acid to yield dihydroxybenzoic acids (DHBAs). RESULTS: Before and after ischemia, there were no differences in coronary flow and heart rate among the four groups, but cardiac output and LV dP/dt maximum in the anesthetic groups were lower than in the control group. Hydroxyl radical products in the heart were significantly lower in the I group than the other groups (e.g. C vs I, 278.1 +/- 24.3 vs 219.3 +/- 14.4 microM x g(-1), P < 0.05). The concentrations of DHBAs in the coronary effluent at some points in the I and H groups were less than in the C and S groups. CONCLUSION: These results indicate that isoflurane and halothane (to a lesser extent), reduce hydroxyl radical production in the ischemic heart, but sevoflurane does not.

Anesthetics, Inhalation↗

PubMed1999

Transmission of and liver injury by TT virus in patients on maintenance hemodialysis.

To study the prevalence and clinical significance of TT virus (TTV) infection in hemodialysis patients, we tested for TTV DNA in serum, using the nested polymerase chain reaction. The prevalence of TTV DNA in 352 hemodialysis patients was 32%, significantly higher than that in 50 healthy blood donors (12%). The prevalence increased with age (P = 0.0098): it was 20% (22/110) in patients aged less than 49 years, 37% (69/188) in those aged 50-69 years, and 41% (22/ 54) in those aged over 70 years. Other clinical features and the prevalence of other hepatitis viral markers tested did not differ between patients with TTV DNA and those without it. The detection rate of hepatitis C virus (HCV) and hepatitis G virus (HGV) viremias increased with duration of hemodialysis and with the number of blood transfusion units, but the prevalence of TTV viremia did not. Twenty-nine of 91 patients followed for 5 years were initially positive for TTV DNA. Of these 29 patients, 17 (59%) carried this viremia for at least 5 years. Fourteen of the 62 patients (23%) who were initially negative for TTV DNA acquired TTV viremia. Serum alanine aminotransferase (ALT) levels were elevated in patients with HCV viremia but not in patients with HGV or TTV viremia. However, the mean ALT level in patients with all three viremias (HCV, HGV, and TTV) was significantly higher than that in patients with one or two of the viremias. More than 30% of the hemodialysis patients had TTV viremia and the carrier state was maintained for years. The hemodialysis procedures, including blood transfusion, did not seem to be crucial for the transmission of TTV. The pathogenic effects of TTV on hepatitis appear to be limited.

Adolescent↗

PubMed1999

Urinary excretion of the vitronectin receptor (integrin alpha V beta 3) in patients with Fabry disease.

A renal disorder is one of the important manifestations of Fabry disease, but the details of the pathogenesis have not been clarified yet. We examined the possibility that the vitronectin receptor (VNR, integrin alpha V beta 3), one of the integrins, is involved in the progression of the renal injury in Fabry disease. We measured the urinary excretion of beta 3 originating from VNR in Fabry patients by immunoblotting analysis and enzyme-linked immunosorbent assay (ELISA). Immunofluorescent microscopic analyses for VNR and globotriaosylceramide were performed on urinary sediments from Fabry patients. Furthermore, beta 3 and vitronectin in kidney tissues were analyzed immunohistochemically. Immunoblotting analysis and ELISA showed that the urinary excretion of beta 3 originating from VNR was significantly increased in the Fabry group compared with both the pathological and healthy control groups. Immunofluorescent microscopy revealed the expression of VNR and accumulation of globotriaosylceramide in urinary sediments from the Fabry patients. Increased expression of beta 3 was observed in glomerular epithelial cells, and in Bowman's capsular epithelial layer and tubular cells, and the amount of vitronectin was moderately increased in the kidney tissues from the Fabry patients. The urinary excretion of VNR was increased, and the expression of VNR was observed in Fabry kidney tissues. The expression of VNR may be involved in the progression of the renal injury in this disease.

Adolescent↗

PubMed1999

Physicochemical properties of amorphous clarithromycin obtained by grinding and spray drying.

In order to characterize the amorphous clarithromycin (CAM) obtained by grinding and spray drying, physicochemical properties (crystallinity, thermal behavior, stability and solubility parameters) were evaluated. From powder X-ray diffraction, it was estimated that the crystalline state of CAM was changed into an amorphous state by grinding and spray drying. In differential scanning calorimetry measurements, both broad and sharp peaks for crystallization were observed in ground samples, whereas spray dried samples showed one broad peak due to crystallization. As to the stability test under high humidity, structural difference was confirmed between ground CAMs and spray dried CAM. The heat of dissolution of ground CAMs was greater than that of intact CAM. In the solubility parameter measurement, the increase of the special term, deltas, indicated that the energy change was due to the polarity of the surface energy of the powder particles by grinding.

Anti-Bacterial Agents↗

PubMed1999

Differences in crystallization behavior between quenched and ground amorphous ursodeoxycholic acid.

PURPOSE: To study the crystallization of ground and quenched ursodeoxycholic acid (UDCA) and to characterize their amorphous states. METHODS: Amorphous UDCA was prepared by grinding and also by rapid cooling of the melt. These samples were characterized by powder X-ray diffraction (XRD), near IR spectra and dynamic water sorption. The heat associated with crystallization was measured in an isothermal microcalorimeter at 25 degrees C at various relative humidities (RH) (50%-100%) and, in the presence of the vapour from a mixed solvent of ethanol and water (ethanol conc. 10%-100%). The specific surface area was calculated from krypton adsorption. Contact angles were measured by using a Wilhelmy plate to calculate the surface energy of the samples. RESULTS: Ground and quenched samples yielded amorphous XRD patterns. Differential scanning calorimetry thermographs of the milled sample revealed that crystallization occurred at around 80 degrees C, whereas the quenched sample did not crystallize. Exposure to humid air did not result in crystallization of either amorphous sample during the microcalorimetric experiments. In the presence of ethanol vapour, the ground sample did, but the quenched sample did not, crystallize. The amount of water sorption into the quenched sample was larger than that of the ground sample at low RH. The surface energy of the quenched material was different to that of the ground. Peak shifts were observed in the NIR spectra at around 1450, 2100 nm, allowing differentiation between the ground and quenched samples. CONCLUSIONS: It can be concluded that different molecular states of amorphous UDCA were obtained depending on the preparation method. The crystallisation of amorphous UDCA was related to the molecular state of disorder.

Crystallization↗

PubMed1999

The Pho85 kinase, a member of the yeast cyclin-dependent kinase (Cdk) family, has a regulation mechanism different from Cdks functioning throughout the cell cycle.

BACKGROUND: The PHO85 gene is a negative regulator of the PHO system in the yeast Saccharomyces cerevisiae and encodes a protein kinase (Pho85p) which is highly homologous to the Cdc28 kinase (Cdc28p). Although the two kinases share a 51% identity and their functional domains are well conserved, PHO85 fails to replace CDC28. Pho85p forms complexes with G1-cyclin homologues, including Pcl1p, Pcl2p and Pcl9p, and is thought to be involved in the cell-cycle regulation at G1 and the end of M. By analysing the genetic and biochemical properties of Pho85p, we studied whether the regulation of Pho85p activity is similar to other cyclin-dependent kinases (Cdks) directly involved in cell cycle regulation. RESULTS: A functional analysis of various Pho85 mutants revealed that E53 in the PSTAIRE sequence was important for Pho85p function. On the other hand, residues in the T-loop including S166, S167 and E168, appeared dispensable for Pho85p function, suggesting that the phosphorylation of S166, corresponding to T161 of Cdc2p and T169 of Cdc28p, was not required for the kinase activity of Pho85p. Instead, we found that phosphorylation of Y18, corresponding to Y15 of Cdc2p and Y19 of Cdc28p, may be important for the binding of Pho80p but not of Pcl1p, suggesting that tyrosine phosphorylation may function as a signal which discriminates various Pho85-cyclins. CONCLUSION: In Cdks functioning throughout the cell cycle, tyrosine phosphorylation is inhibitory to the activation of kinase, whereas the phosphorylation of threonine in the T-loop is essential for activation. Our finding indicates that the regulation mechanism of Pho85p activation appears to be distinct from these Cdks.

Amino Acid Motifs↗

PubMed1999

Las21 participates in extracellular/cell surface phenomena in Saccharomyces cerevisiae.

Las21 (Yj1062W) is a member of the major facilitator super family, possessing multimembrane spanning domains. The LAS21 gene was identified as a responsible gene for a Saccharomyces cerevisiae mutan which shows sensitivity to a local anestheticum, tetracaine. The null las21 mutant (las21 delta) is viable but shows temperature sensitive growth. We found, in addition to this phenotype, that the las21 delta strain shows a number of defects; mating deficiency, calcofluor resistance, and formation of Zymolyase sensitive spores. Temperature sensitive growth of the las21 delta mutant was found to be suppressed by 0.1 M MgSO4. Two multicopy suppressors were obtained. They are ECM33 (YBR078W) and PIR2/HSP150 (YJR159W) both have some roles in an extracellular function. The common features of the suppressors, genetic and physiological, of the las21 delta mutation suggest that Las21 participates in a global activity of extracellular phenomena. The las 21 phenotypes are consistent with the idea that Las21/Gpi7 acts in metabolism of glycosylphosphatidylinositol.

Benzenesulfonates↗

PubMed1999

[Hyperkalemia after irradiated blood transfusion].

A 70-yr-old woman was scheduled for hepatectomy and colectomy. We gave general anesthesia with N2O-O2-Isoflurane and continuous epidural block. About 4.5 hours after the start of the operation, 8 units of irradiated RBC-MAP were transfused. Then elevated T waves were noted and serum potassium was increased to 5.4 mmol.l-1. The transfusion of RBC-MAP was stopped and calcium gluconate was administered immediately. Then serum potassium decreased to 4.3 mmol.l-1 and ECG returned to normal. During the operation, 10 units of irradiated RBC-MAP were transfused and 8 units of them had been stored more than 1 week after the irradiation. We suspect that hyperkalemia was induced by high concentration of potassium in RBC-MAP. Irradiation of blood products is an effective way to prevent post-transfusion graft versus host disease. However, the increase in potassium is greater in the irradiated than nonirradiated RBC-MAP. We must pay attention to the high concentration of potassium in th eplasma of RBC-MAP stored after irradiation.

Aged↗

PubMed1999

[Premixing of 5% dextrose in Ringer's acetate solution with propofol reduces incidence and severity of pain on propofol injection].

The purpose of this study was to compare the effect of premixed 5% dextrose in Ringer's acetate solution and premixed lidocaine with propofpl on the reduction of pain during injection of propofol in adult patients. We conducted a prospective, randomized, double-blinded trial. Ninety-six patients were randomly allocated to one of three groups according to the agents added to 1% propofol 20 ml; Group C, normal saline 2 ml, Group L, 2% lidocaine 2 ml, and Group A, 5% dextrose in Ringer's acetate solution 2 ml. The pain on injection was rated as none, mild, moderate, or severe. Seventy percent of patients in the C group experienced pain, while 33% and 25% of patients experienced pain in the A group and the L group, respectively. Forty-two percent of patients in the C group complained moderate to severe pain but only one patient in both A group and L group. In conclusion, 5% dextrose in Ringer's acetate solution premixed with 200 mg propofol significantly reduces incidence and severity of pain associated with propofol injection and is easier to use than premixed lidocaine.

Adult↗

PubMed1998

Right ventricular responses to vagus stimulation of fibers to discrete cardiac regions in dog hearts.

To investigate the role on the right ventricular function of the parasympathetic nerves in discrete cardiac regions, we studied the effects of stimulation of the intracardiac parasympathetic nerves to the atrioventricular (AV) nodal area (AVPS) or sinoatrial (SA) nodal area (SAPS), and stimulation of the cervical vagus nerves (CVS) on the right atrial and ventricular function in the autonomically decentralized heart of the anesthetized dog. AVPS prolonged AV conduction time (AVCT) and decreased the ventricular rate without changes in atrial rate, right atrial 'a' wave pressure (RAP), its first derivative (RAd P/dt), right ventricular pressure (RVP) and its first derivative (RVd P/dt) in the spontaneously beating heart. On the other hand, AVPS prolonged the AVCT in the atrium paced electrically and further decreased the ventricular rate with decreases in ventricular pressure responses but not atrial responses. SAPS decreased atrial and ventricular rates without AVCT changes and attenuated the right atrial and ventricular pressure responses. In the atrial paced heart, SAPS decreased the ventricular responses less than those responses in the spontaneously beating heart with similar decreases in the atrial pressure responses, but it changed neither the AVCT nor ventricular rate. On the other hand, CVS decreased the atrial and ventricular rate or pressure responses, and increased the AVCT. CVS in the paced heart also decreased the atrial and ventricular pressure responses with the prolongation of AVCT. The cardiac responses to parasympathetic stimulations were abolished by atropine. These results suggest that AVPS decreases ventricular rate without direct right ventricular pressure effects but the negative chronotropic effects of AVPS and SAPS decrease the ventricular pressure responses rate-dependently in the dog heart.

Animals↗

PubMed1998

Fluorometric Studies of Pyrene Adsorption on Porous Crystalline Cellulose.

Pyrene crystals were physically mixed with either porous crystalline cellulose (PCC) or octa decyl siryl silica-80Tm (ODS). Solid-state fluorescence spectra of pyrene were analyzed to estimate the interaction between pyrene and porous materials. Pyrene monomer emission was observed at 398 nm immediately after being mixed with PCC, while pyrene crystals showed only excimer emission at 475 nm, indicating that the pyrene molecules adsorbed onto the PCC surface in a short period. For the PCC system containing 1.0% pyrene, long-term storage caused an increase in the intensity of excimer-like emission peak at 477 nm accompanied by a decrease in the intensity of monomer emission peak at 398 nm. For the ODS system containing 1.0% pyrene, spectrometric changes were similar to those for the PCC system. In the process of interaction formation between pyrene and an additive, a two-step mechanism was proposed, i.e., the adsorption of pyrene molecules onto the surface of porous additives, and the formation of a ground state dimer of pyrene. The formation of dimeric pyrene could be associated with the surface polarity of additives. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

X-ray triple refraction and triple absorption in a cobalt-complex crystal.

X-ray triple refraction and triple absorption have been quantitatively measured for the first time. The samples were (100)-, (010)- and (001)-oriented plates of a cobalt-complex monoclinic crystal. The apparatus used was an energy-tunable X-ray polarimeter with a phase retarder. The X-ray energy was scanned over a range of 150 eV near the cobalt K-absorption edge. Both the spectra of ellipticity and rotation of polarization were completely different for each crystal plate, which revealed that the biaxial crystal had three refractive indices and three absorption coefficients in the X-ray region. The Kramers-Kronig relation between the real and imaginary parts of the dielectric anisotropy has been quantitatively confirmed for all three different orientations.

Journal Article↗