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Biomedical subjects

H Oyanagi

Publications and source records attributed to H Oyanagi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Enteral nutrition prevents bacterial translocation but does not improve survival during acute pancreatitis.

OBJECTIVE: To evaluate the effect of enteral nutrition (EN) in attenuating bacterial and/or endotoxin translocation, maintaining immune responsiveness, and improving outcome in early acute pancreatitis (AP) in Wistar male rats. DESIGN: Acute pancreatitis was induced in rats receiving total parenteral nutrition (TPN) (AP/TPN group) (n=34) and EN (AP/EN group) (n=35) by pressure injection of 1% deoxycholate into the biliopancreatic duct (0.6 mg/kg of body weight). Rats in the sham/TPN and sham/EN groups (n=10 each) underwent laparotomy without induction of AP. Catheters for TPN and EN were placed into the external jugular vein and jejunum, respectively. Rats were infused with Ringer lactate solution for 48 hours followed by TPN in the AP/TPN and sham/TPN groups, and EN in the AP/EN and sham/EN groups until day 7. The fluid volume and energy (calories) intake were similar in all groups. SETTING: Medical school research laboratory. MAIN OUTCOME MEASURES: Survival, blood endotoxin level, villus height, 5-bromo-2'-deoxyuridine (BrdU) uptake in the jejunum and ileum, bacterial culture of mesenteric lymph nodes, and CD4/CD8 ratio of T cells in mesenteric lymph nodes, spleen, and peripheral blood. RESULTS: There was no difference in survival and pancreatic healing between the AP/TPN and AP/EN groups. Colony-forming units of the mesenteric lymph nodes and the endotoxin level were significantly lower in the AP/EN group than in the AP/TPN group (P<.05). Villus height and BrdU intake was significantly higher in the AP/EN group than in the AP/TPN group (P<.05). The CD4/CD8 ratio of T cells in spleen and peripheral blood was higher in the AP/EN group than in the AP/TPN group (P<.05), whereas there was no difference in mesenteric lymph nodes. CONCLUSIONS: Jejunal administration of EN is well tolerated in early AP, maintains immune responsiveness and gut integrity, and reduces bacterial and/or endotoxin translocation. However, compared with TPN, EN does not improve outcome. These results suggest that factors other than bacterial and/or endotoxin translocation may be responsible for mortality in this rat model of early AP. However, additional studies of both early bacterial and/or endotoxin translocation and late assessment of outcome are indicated.

Acute Disease↗
PubMed1999

Handlebar hernia: case report and review of pediatric cases.

The authors describe a rare case of handlebar hernia in a 9-year-old-boy. All layers of his abdominal wall were disrupted by a fall on a bicycle; however, his skin and intra-abdominal organs were completely intact. Computed tomography demonstrated subcutaneous intestinal loops protruding through the rent. Surgical repair was performed, and his postoperative course was uneventful.

Abdominal Muscles↗
PubMed1998

Pump and probe X-ray absorption fine structure using high-brilliance photon sources.

Pump and probe X-ray absorption fine structure (XAFS) is used as a local probe of excited atoms, which can provide direct information on lattice distortion, relaxation and atomic rearrangements associated with electronic excitations. In situ XAFS experiments during optical excitation are reported. Utilizing a grazing-incidence fluorescence excitation, which minimizes the mismatch between the probing depths of X-ray excitation and optical pumping, it is found that the dominant photoinduced defect state in amorphous selenium at low temperature is a pair of threefold neutral $C^0_3$ states: $2C^*_2 \rightarrow (C^0_3-C^0_3)$, where $C^*_2$ denotes the twofold excited lone-pair state. The results indicate that optical pumping of chalcogen atoms at low temperature leads to locally over-coordinated defect pairs similar to those in the liquid state. The origin of reversible photostructural changes, such as photodarkening or photoinduced fluidity, is attributed to the structural disorder caused by the formation and annihilation of dynamical interchain bonds during optical melting.

Journal Article↗
PubMed1998

Development of a compact six-circle goniometer.

A compact versatile six-axis goniometer has been built which can be used with the scattering plane vertical or horizontal for anomalous X-ray diffraction and diffraction X-ray absorption fine structure using a tunable X-ray undulator at SPring-8. The diffractometer consists of a four-circle goniometer for the standard omega, 2theta, phi and chi motions and a two-circle goniometer on the 2theta arm for mounting the detector and analyser crystal. The goniometer is controlled via Ethernet, and standard data-acquisition software with a graphical user interface has been developed. A closed-cycle helium cryostat is mounted on the omega axis for temperature-dependent experiments from 330 K to 14 K. Preliminary experiments on a Bi(2)Sr(2)CaCu(2)O(8) single crystal demonstrate the performance. Superstructure peaks due to the one-dimensional spatial modulations in the b axis were recorded as a function of temperature above 20 K using an image plate.

Journal Article↗
PubMed1998

A new apparatus for polarized X-ray absorption fine structure using a grazing-incidence fluorescence excitation.

A new apparatus is described for surface-sensitive X-ray absorption fine structure (XAFS) at the 27-pole wiggler beamline BL13B at the Photon Factory. The apparatus is designed for polarized XAFS experiments at low temperature. A closed-cycle helium cryostat is rotated around the omega axis of a vertically mounted high-precision goniometer. The apparatus can be used for XAFS and X-ray standing-wave experiments, sharing a 19-element pure-Ge detector array as a fluorescence detector. The available temperature range is 15-300 K. The performance is demonstrated by in-plane polarized Cu K-EXAFS for a YBa2Cu307 thin film (approximately 1000 A) epitaxically grown on an SrTiO3 single crystal. An in-situ study of amorphous selenium under optical excitation revealed that neutral defect pairs (C3(0)-C3(0)) are formed by photoexcitation of lone pairs. This indicates that grazing-incidence fluorescence excitation is advantageous for 'pump-and-probe' experiments which can minimize the mismatch in the probing depth between X-ray and optical excitation.

Journal Article↗
PubMed1998

[Clinical significance and problems in parenteral nutritional care].

The clinical indications for and types of intravenous nutritional support are reviewed from the standpoint of their advantages and disadvantages. Total parenteral nutrition (TPN, also known as intravenous hyperalimentation) improves and maintains not only nutritional status but immunocompetence in patients with restricted food intake, because almost all essential nutritional substrates can be administered in the parenteral root alone to meet energy requirements. In surgical fields, TPN reduces perioperative risk and complication rates and enhances postoperative recovery of patients with severe stress such as those under going thoracic esophagectomy or pancreatoduodenectomy. In addition to calory administration, another type of parenteral nutrition a the disease-specific formulation has been attempted to improve directly such pathophysiologic conditions as renal failure, hepatic failure, or sever acute pancreatitis. Despite the great benefits of TPN, it is associated with several complications related to the indwelling catheter or to inadequate substrates administered, Disuse atrophy of the intestinal mucosa in patients receiving TPN to decreases the host defense against bacterial infection. To avoid the abuse of TPN, the indications for it should be selected rigorously. Moderate calory administration of a maximum of 15-20 cal/kg/day via a peripherally inserted catheter has been reevaluated in patients on short-term fasts.

Humans↗
PubMed1997

Intratumoral necrosis of lung carcinoma: a potential diagnostic pitfall in incremental dynamic computed tomography analysis of solitary pulmonary nodules?

The authors determined the pattern and enhancement range of necrotic lung carcinoma using incremental dynamic computed tomography (CT). Thirty-seven pathologically proven lung cancers (range, 8-57 mm in diameter) were evaluated using incremental dynamic CT. Scans were obtained before and 30 seconds, 2 minutes, and 5 minutes after the onset of contrast material injection. Computed tomography numbers in circular regions of interest (60% of tumor diameter) were calculated, and the difference in CT number between nonenhanced and the scan showing maximum attenuation was determined. In cavitary necrotic carcinomas, regions of interest were established excluding areas of cavitation. Nine (24%) of 37 lung carcinomas had intratumoral necrosis; four (11%) had noncavitary necrosis, and five (14%) had cavitary necrosis. Maximum attenuation of four noncavitary necrotic carcinomas (mean 31 +/- standard deviation 25 HU; range, -3-56 HU) was lower than cavitary necrotic carcinomas (42 +/- 8 HU; range, 35-51 HU; p = 0.36) and non-necrotic carcinomas (48 +/- 17 HU; range, 25-91 HU; p = 0.07). All carcinomas showed maximum attenuation > or = 25 HU except for one noncavitary necrotic carcinoma (maximum attenuation = -3 HU; 36 mm in diameter). Noncavitary necrosis was recognized as low attenuation on noncontrast scan in two of four cases and as an unenhanced area on enhanced scan in four of four cases. Although noncavitary necrotic lung carcinoma may rarely show maximum attenuation < or = 15 HU, necrotic material is recognized as unenhanced area on enhanced scan.

Aged↗
PubMed1995

Nitrite reductase from the magnetotactic bacterium Magnetospirillum magnetotacticum. A novel cytochrome cd1 with Fe(II):nitrite oxidoreductase activity.

Cytochrome cd1 nitrite reductase was isolated from magnetite-containing cells of the magnetotactic bacterium Magnetospirillum (formerly Aquaspirillum) magnetotacticum, which was microaerobically cultivated under denitrifying conditions. The enzyme showed absorption maxima at 643 nm and 409 nm in the oxidized form, and at 663, 551, 522, and 418 nm in the reduced form. A distinctive split absorption band did not occur at about 550 nm. The pyridine ferrohemochrome spectra suggested the presence of heme c and heme d1 in the molecule. The enzyme was composed of two identical subunits each with a molecular mass of 54 kDa; each subunit contained one c-type and one d-type heme. The isoelectric point was 9.2. The redox potentials of heme c and heme d1 were estimated to be +191 mV and +180 mV, respectively. Although the enzyme showed cyanide-sensitive N,N,N',N'-tetramethyl-p-phenylenediamine-O2 oxidoreductase activity and N,N,N',N'-tetramethyl-p-phenylenediamine-nitrite oxidoreductase activity, the enzyme did not oxidize M. magnetotacticum ferrocytochrome c-550 and Pseudomonas aeruginosa ferrocytochrome c-551 in the presence of nitrite. Furthermore, sodium succinate did not cause the reduction of cytochrome cd1 in the crude cell-free extract prepared from the magnetite-containing bacterial cells. However, M. magnetotacticum cytochrome cd1 showed a novel Fe(II):nitrite oxidoreductase activity whereas P. aeruginosa cytochromes cd1 had no Fe(II):nitrite oxidoreductase activity. These results suggest that M. magnetotacticum cytochrome cd1 may function as a Fe(II)-oxidizing enzyme under microaerobic conditions using nitrite as electron acceptor.

Cytochrome c Group↗