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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 19 recordsLinked to original sources
PubMed2006

Randomized clinical trial of hepatectomy using intermittent pedicle occlusion with ischaemic intervals of 15 versus 30 minutes.

BACKGROUND: The optimal ischaemic interval during hepatectomy with intermittent pedicle occlusion (IPO) remains to be established. The aim of the present randomized clinical trial was to compare the short-term outcome of hepatectomy using IPO with an ischaemic interval of 15 versus 30 min. METHODS: Between October 2002 and September 2004, 108 consecutive patients scheduled to undergo hepatectomy without bilioenterostomy were enrolled. During liver transection, IPO was performed with an ischaemic interval of either 15 min with 5 min of reperfusion (standard group, SG) or 30 min with 5 min of reperfusion (prolonged group, PG). After randomization and subsequent exclusion of certain patients, 44 patients in the SG and 48 in the PG were analysed. RESULTS: The mean(s.d.) bilirubin ratio (serum total bilirubin level on day 2 after operation divided by the preoperative level) was 1.6(0.8) in the SG and 1.7(0.8) in the PG (P = 0.874). The transection area per unit transection time was significantly greater in the latter group (median (range) 1.0 (0.4-2.1) versus 0.8 (0.0-1.5) cm(2)/min; P = 0.046). CONCLUSION: There was no difference in the bilirubin ratio when IPO was carried out for 30 or 15 min. By extension of IPO to 30 min, a greater resection area per unit time was possible with preservation of remnant liver function.

Adult↗
PubMed2006

Evaluation of hydrological processes in a mountainous small basin using a quinone biomarker.

An applicability of quinone biomarker to the analysis of hillslope runoff was investigated. At first, quinone profiles of three streams as well as a hillslope runoff in a forested headwater catchment were compared. The quinone composition of hillslope runoff differed from others. Moreover, there were remarkable differences in quinone profile of hillslope runoff under different rainfall conditions. Then, the behavior of quinone biomarker during the increase and decrease of hillslope runoff after a rainfall event was examined. The fractional changes in Q-9 (H2), Q-10 (H2), Q-11, MK-6 and MK-10 suggested the effect of interflow.

Biomarkers↗
PubMed2006

[Avoidance of patient-prosthesis mismatch].

To minimize the incidence of patient-prosthesis mismatch (PPM), we have routinely adopted aortic root enlargement to avoid PPM for patients with small aortic annulus. The aim of this study was to review our strategy of avoiding PPM. The Carpentier-Edwards Perimount (CEP) valves were implanted in 53 patients who were mostly aged over 65 and the St. Jude Medical (SJM) mechanical valves were used in 128 patients aged under 65. A standard 21-mm SJM valve was used in only 3 patients and no 19-mm valves were employed. However, 19-mm CEP valves were used in 12 patients with a small body surface area (1.43 +/- 0.14 m2). Of these, 26 patients (14.4%) who had a small aortic annulus and 24 patients aged under 65 underwent aortic root enlargement. No patient receiving an SJM valve had an projected indexed effective orifice area (EOAI) < or = 0.85 cm2/m2 because of performing aortic valve replacement (AVR) with annular enlargement and only 2 (3.8%) out of 53 patients receiving CEP valves developed PPM. Consequently, the prevalence of PPM was 1.1% in this series. The prevalence of PPM was low in patients over 65 years old with a relatively small body size who received bioprosthetic valves. A pericardial bioprosthesis was considered to be an appropriate valve in older population with regard to avoiding PPM. In patients under 65 years old with a small annulus, the first choice for avoiding PPM is aortic annular enlargement, which may be avoided by high performance mechanical valves with larger EOA.

Adult↗
PubMed2005

Spontaneous regression of hepatocellular carcinoma with complete necrosis: case report.

Spontaneous regression of hepatocellular carcinoma is rare phenomenon. A 74-year-old man was found to have a hepatocellular carcinoma with intrahepatic metastases in the lateral segment of the liver. Before surgery, he developed severe cholangitis due to choledocholithiasis and was treated endoscopically. The tumor marker level decreased markedly, and hepatectomy was performed. The resected tumor demonstrated complete necrosis.

Aged↗
PubMed2005

Current clamp at zero level in JT-60U current hole plasmas.

It is found that no current is driven in a central region of a tokamak plasma once the central current density becomes nearly zero ("current hole"), in spite of high electric conductivity, at the current drive by a toroidal electric field and a radio-frequency wave in experiments on the JT-60U tokamak. This is a new, stiff, self-organized structure of a magnetic field in an axisymmetric toroidal plasma.

Journal Article↗
PubMed2005

Acute stress reduces intraparenchymal lung natural killer cells via beta-adrenergic stimulation.

There are lines of evidence that natural killer (NK) cells are sensitive to physical and psychological stress. Alterations in the immune system including NK cells are known to differ among tissues and organs. The effect of stress on the lung immune system, however, has not been well documented in spite of the fact that the lungs always confront viral or bacterial attacks as well as tumour cell metastasis. In this study, we intended to investigate the effect of restraint stress on lung lymphocytes including NK cells. C57BL/6 mice were exposed to 2 h restraint stress. The concentration of plasma epinephrine significantly rose immediately after the release from restraint as compared to home-cage control mice. Flow cytometric analysis revealed that the numbers of most lymphocyte subsets including NK cells were decreased in the lungs and blood but not in the spleen, immediately after restraint stress. Immunohistochemical examination revealed that the number of NK cells was decreased in the intraparenchymal region of the lungs, while the number of alveolar macrophages did not change. The decrease in the number of NK cells in the lungs and blood was reversed by the administration of propranolol, a nonselective beta adrenergic antagonist. Taken together, our findings suggest that acute stress reduces the number of intraparenchymal lung NK cells via activation of beta adrenergic receptors.

Adrenergic beta-Antagonists↗
PubMed2005

[Off-pump coronary artery bypasssurgery in patients with mitral regurgitation].

Introduction of off-pump coronary artery bypass grafting (off-pump CABG : OPCAB) makes it possible to shorten the bypass time and cardiac arrest time in patients with both ischemic heart disease and valvular disease. This may be beneficial in patients with poor cardiac function and renal dysfunction. However, it is unclear whether such patients can tolerate the changes of hemodynamics during vertical displacement of the heart. In 3 patients who had ischemic heart disease with non-ischemic mitral regurgitation, we performed OPCAB prior to mitral valve plasty. The changes of mitral regurgitation observed by transesophageal echocardiography and several hemodynamic parameters were monitored as the heart was moved to various positions during OPCAB. When a heart positioner (Starfish) was used, hemodynamic deterioration was not observed, and there was also no aggravation of mitral regurgitation. Based on these results, we conclude that it may be possible to carry out OPCAB safely in patients with associated mitral regurgitation.

Adult↗
PubMed2004

Site-specific effect of ascorbic acid deficiency on the structure and function of odontoblasts in the teeth of osteogenic disorder rat in vivo.

The influence of chronic L-ascorbic acid (AsA) deficiency on dentinogenesis was examined in Osteogenic Disorder Shionogi (ODS) rat, which bear inborn lack of L-gulonolactone oxidase. Weanling male rats were kept on AsA-free diet for 4 weeks until all suffered from scurvy. Control rats were given AsA in drinking water. The dentin of molars and incisors of the scorbutic rats was thinner than that in control, except for the crown-analogue (enamel-related) of incisors. Predentin in scorbutic molars showed irregular thickness, and was almost lacking in roots. In the root-analogue (cementum-related) region of scorbutic incisors, dentin displayed metachromatic incremental lines, and the thickened predentin contained collagen fibrils of irregular diameter. The odontoblasts facing the affected regions contained dilated rough endoplasmic reticulum cisternae. In the crown-analogue of scorbutic incisors, however, dentin, predentin, and odontoblasts were comparable to those of controls. These data indicate that AsA deficiency differentially affects the synthetic and/or secretory activity of odontoblasts in ODS rat teeth in a site-specific manner. The regional differences implicate the presence of putative local factor(s) in the crown-analogue of incisors that might have compensated for AsA deficiency. The odontoblasts in the crown-analogue of incisors may have different requirements for AsA from those in molars and the root-analogue of incisors.

Animals↗
PubMed2004

Ethanol stimulates glycogenolysis and inhibits both glycogenesis via gluconeogenesis and from exogenous glucose in perfused rat liver.

AIMS: Although it is commonly recognized that ethanol suppresses gluconeogenesis, the influence of alcohol intake on blood glucose levels remains controversial. Ethanol may act on both glucose production and glucose consumption in the liver. Thus, we studied each effect of ethanol on glucose oxidation, gluconeogenesis, glycogenesis and glycogenolysis in the liver. METHODS: The rat liver was isolated and cyclically perfused with a medium containing 50 mmol/l ethanol. RESULTS: Ethanol enhanced 14C-glucose oxidation in the liver from 1.09 +/- 0.11 to 1.41 +/- 0.14 micromol for 20 min (p < 0.05). Gluconeogenesis from 14C-lactate was markedly reduced by ethanol from 8.0 +/- 1.3 to 1.5 +/- 0.6 micromol for 12 min (p < 0.01). Ethanol increased glycogenolysis (net hepatic glucose output, 0.47 +/- 0.10 vs. 0.22 +/- 0.04 mmol/30 min, p < 0.01), and then decreased hepatic glycogen content (179 +/- 38 vs. 273 +/- 39 mg in the presence of 1 mU/ml insulin after 30 min of perfusion, p < 0.05). Ethanol decreased the direct glycogenesis from 14C-glucose from 0.55 +/- 0.08 to 0.33 +/- 0.05 micromol per 100 mg glycogen for 30 min (p < 0.01). Ethanol inhibited the indirect glycogenesis from 14C-lactate from 0.21 +/- 0.04 to 0.09 +/- 0.01 micromol per 100 mg glycogen for 30 min (p < 0.01). DISCUSSION: The influence of ethanol on the blood glucose regulation by the liver seems to be different between fasted and fed states. Namely, ethanol has both the hypoglycemic effects through decreased gluconeogenesis and increased glucose oxidation and the hyperglycemic effects through decreased glycogenesis and increased glycogenolysis.

Animals↗
PubMed2004

Supernumerary muscle bundles in the submental triangle: their positional relationships according to innervation.

The positional relationships between the supernumerary muscle bundles within the submental triangle and their innervating branches from the mylohyoid nerve were investigated. Ten heads of Japanese cadavers that showed aberrant muscle bundles within the submental triangle were examined. Three additional heads without such aberrant bundles were used for comparison. All cadavers were fixed with 8% formalin and preserved in 30% ethanol. After the examination of the origin and insertion of the muscles, the bony elements were removed, and then their innervating branches from the mylohyoid nerve were examined in detail under a binocular microscope. In 11 head-halves of six cadavers unilateral supernumerary bundles were found. Right and left mylohyoid nerves gave off branches that crossed the inner surface of the bundles of each respective side. Supernumerary bundles ran across the median line in two heads. In one head, the twigs from the mylohyoid nerve of the same side as the mandibular origin entered the inner surface of the bundles. The other head received double innervation from right and left nerves. Three heads showed supernumerary bundles that attached to the mandible or the hyoid bone at one end and joined the mylohyoid muscle at the other end. The branches from the mylohyoid nerve of the digastric side entered the inner surface of the bundles, and those of the mylohyoid side entered their outer surface. After giving off branches to the muscles, the mylohyoid nerve continued as a cutaneous nerve of the submental region. Based on the innervation patterns of the aberrant bundles within the submental triangle, it was suggested that these bundles result from the combination of the remnants of the primordia of the mylohyoid muscle and the anterior belly of the digastric.

Aged↗
PubMed2004

Formation of advanced tokamak plasmas without the use of an ohmic-heating solenoid.

A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This was accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, and the loop voltage supplied by the vertical field and shaping coils. The Ohmic heating (OH) solenoid was not used but a small inboard coil (part of the shaping coil), providing less than 20% of total poloidal flux, was used. The plasma thus obtained had both internal and edge transport barriers, with an energy confinement time of 1.6 times H-mode scaling, a poloidal beta of 3.6, and a normalized beta of 1.6, and a large bootstrap current fraction (>90%). This result opens up a possibility to reduce, and eventually eliminate, the OH solenoid from a tokamak reactor, which will greatly improve its economic competitiveness.

Journal Article↗
PubMed2004

Interleukin-8 is involved in cervical dilatation but not in prelabour cervical ripening.

Our aim was to determine the amount and source of interleukin (IL)-8 and to study IL-8 receptor expression in the human cervix during pregnancy and after labour. Cervical biopsies were obtained from six non-pregnant women, eight women undergoing pregnancy termination, 17 women undergoing elective caesarean section and 11 women after vaginal delivery. IL-8 levels were compared in women with and without a ripe cervix, as determined by cervical Bishop score and cervicovaginal fetal fibronectin levels. Levels of IL-8 and IL-1beta, a regulator of IL-8 expression, were determined by enzyme-linked immunosorbent assay (ELISA). IL-8, IL-1beta and IL-8 receptor proteins were localized by immunohistochemistry. Compared with late pregnancy, IL-8 levels increased after labour and vaginal delivery (P < 0.01) but there was no correlation with cervical ripening. IL-8 was localized to stromal cells, macrophages and granulocytes. There were no significant differences in IL-1beta levels between groups. IL-8 receptors were expressed primarily on granulocytes and macrophages after vaginal delivery. We conclude that IL-8 is involved in cervical dilatation but not in cervical ripening.

Cervical Ripening↗
PubMed2003

Spatial relationships between masticatory muscles and their innervating nerves in man with special reference to the medial pterygoid muscle and its accessory muscle bundle.

The relationships between the positional arrangement of the surrounding and innervating nerves of the muscles supplied by the mandibular nerve, in particular those medial to the main trunk of the nerve, were examined in 24 head halves from 12 Japanese cadavers by dissection from the inside after removal of the bony elements except for the mandible. In ten sides of five heads, the lingual nerve pierced the medial pterygoid muscle, and the bundle lateral to the nerve was found to be separated as an accessory muscle bundle. The accessory bundle was frequently attached to the mylohyoid muscle. In addition, the inferior alveolar nerve and the lingual nerve frequently communicated, and in four specimens a branch from the lingual nerve entered the mylohyoid to communicate with the proper nerve. The innervation pattern indicated that the medial pterygoid muscle consists of the anteromedial and the posterolateral main parts, and sometimes has an accessory bundle. Based on the present findings and the previous studies of the positional relationships between the muscles and nerves by our research group, we propose that the muscles innervated by the mandibular nerve could be classified as an inner group (the lateral pterygoid) and an outer group (the other muscles). A possible scheme of the positional relationships between the muscles and nerves is presented.

Aged↗
PubMed2003

Scavenger receptors for oxidized and glycated proteins.

Our present knowledge on chemically modified proteins and their receptor systems is originated from a proposal by Goldstein and Brown in 1979 for the receptor for acetylated LDL which is involved in foam cell formation, one of critical steps in atherogenesis. Subsequent extensive studies using oxidized LDL (OxLDL) as a representative ligand disclosed at least 11 different scavenger receptors which are collectively categorized as "scavenger receptor family". Advanced glycation endproducts (AGE) and their receptor systems have been studied independently until recent findings that AGE-proteins are also recognized as active ligands by scavenger receptors including class A scavenger receptor (SR-A), class B scavenger receptors such as CD36 and SR-BI, type D scavenger receptor (LOX-1) and FEEL-1/FEEL-2. Three messages can be summarized from these experiments; (i) endocytic uptake of OxLDL and AGE-proteins by macrophages or macrophage-derived cells is mainly mediated by SR-A and CD36, which is an important step for foam cell formation in the early stage of atherosclerosis, (ii) selective uptake of cholesteryl esters of high density lipoprotein (HDL) mediated by SR-BI is inhibited by AGE-proteins, suggesting a potential pathological role of AGE in a HDL-mediated reverse cholesterol transport system, (iii) a novel scavenger receptor is involved in hepatic clearance of plasma OxLDL and AGE-proteins.

Animals↗
PubMed2003

Effects of deicing salt on the vitality and health of two spruce species, Picea abies Karst., and Picea glehnii Masters planted along roadsides in northern Japan.

In northern Japan, the growth of Picea abies Karst., and Picea glehnii Masters, which have been planted along the highways, is often suppressed due to several environmental stresses. To examine the adverse effects of deicing salt, the primary source of stress,we measured needle life span, photosynthetic capacity, and water potential and transpiration rate of the two spruce species at a site with damaged trees, near the roadside and a site with healthy trees, located far from the highway. Results from the analysis showed large amounts of sodium and chlorine in the soil and snow at the damaged site. These elements had accumulated in the needles of the spruce. Moreover, physiological traits of the spruce, at the damaged site were also affected. Therefore, we concluded that poor physiological traits might be attributed to an accumulation of deicing salt in the needles, resulting in the suppression of tree growth.

Absorption↗
PubMed2003

Conversion coefficients from fluence to effective dose for heavy ions with energies up to 3 GeV/A.

Radiological protection against high-energy heavy ions has been an essential issue in the planning of long-term space missions. The fluence to effective dose conversion coefficients have been calculated for heavy ions using the particle and heavy ion transport code system PHITS coupled with an anthropomorphic phantom of the MIRD5 type. The calculations were performed for incidences of protons and typical space heavy ions--deuterons, tritons, 3He, alpha particles, 12C, 20Ne, 40Ar, 40Ca and 56Fe--with energies up to 3 GeV/A in the isotropic and anterior-posterior irradiation geometries. A simple fitting formula that can predict the effective dose from almost all kinds of space heavy ions below 3 GeV/A within an accuracy of 30% is deduced from the results.

Algorithms↗
PubMed2003

Analysis of dose-LET distribution in the human body irradiated by high energy hadrons.

For the purposes of radiological protection, it is important to analyse profiles of the particle field inside a human body irradiated by high energy hadrons, since they can produce a variety of secondary particles which play an important role in the energy deposition process, and characterise their radiation qualities. Therefore Monte Carlo calculations were performed to evaluate dose distributions in terms of the linear energy transfer of ionising particles (dose-LET distribution) using a newly developed particle transport code (Particle and Heavy Ion Transport code System, PHITS) for incidences of neutrons, protons and pions with energies from 100 MeV to 200 GeV. Based on these calculations, it was found that more than 80% and 90% of the total deposition energies are attributed to ionisation by particles with LET below 10 keV microm(-1) for the irradiations of neutrons and the charged particles, respectively.

Body Burden↗