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Biomedical subjects

Y Sugawara

Publications and source records attributed to Y Sugawara.

At least 19 recordsLinked to original sources
PubMed2003

Left liver grafts for patients with MELD score of less than 15.

Left liver grafts are now seldom used for adult recipients of living donor liver transplantations because the left liver is believed to be insufficient to meet patient metabolic demands. At the University of Tokyo Hospital, left liver grafts have been limited to patients with fulminant hepatic failure or chronic hepatic failure with a model for end-stage liver disease (MELD) score of less than 15. Since 2000 25 adult patients received left liver grafts. The mean graft weight to standard liver volume ratio was 44%. The rates of acute rejection, vascular, and biliary complications were 24%, 0%, and 25%, respectively. All patients survived the operation and are doing well with a mean follow-up of 17 months. The present results suggest that left liver grafts provide acceptable results among patients satisfying our criteria.

Adult↗
PubMed2003

Disturbance of neural respiratory control in neonatal mice lacking GABA synthesizing enzyme 67-kDa isoform of glutamic acid decarboxylase.

To examine the role of GABA in the respiratory rhythm and pattern generation in neonatal mice, we analyzed the function of the respiratory control system of 67-kDa isoform of glutamic acid decarboxylase (GAD67)-deficient neonatal mice. In these mutant (GAD67-/-) mice, GABA levels in the brainstem were reduced to about 30% of those in wild-type (GAD67+/+) mice. In in vivo preparations, ventilatory parameters were analyzed by whole body plethysmography and electromyography of intercostal muscles. GAD67-/- mice exhibited abnormal respiratory patterns, i.e. irregular respiratory rhythm, and periodic gasp-like respiration followed by shallow breathing with short inspiratory duration and apnea. In in vitro GAD67-/- brainstem-spinal cord preparations, inspiratory C4 burst duration was shorter than that in GAD67+/+ preparations. Whole cell recordings revealed that activities of inspiratory neurons in the ventral medulla of GAD67-/- mice were characterized by a short depolarization period and a paucity of firing during the inspiratory phase. Superfusion of the in vitro GAD67-/- preparation with 10 microM GABA prolonged C4 burst duration and partly restored a normal pattern of inspiration, although the restoration was limited. These results indicate that reduced GABA levels during the perinatal period induce malfunction in the respiratory control system. We suggest that GABAergic transmission is not essential for basic respiratory rhythm generation but plays an important role in the maintenance of regular respiratory rhythm and normal inspiratory pattern in neonatal mice.

Animals↗
PubMed2003

Hemichrome formation observed in human haemoglobin A under various buffer conditions.

AIM: To observe hemichrome formation in human haemoglobin A under various buffer conditions. METHOD: Hemichrome formation of human oxyhaemoglobin A (HbO2) was studied spectrophotometrically in 0.1 m buffer at various temperatures and pH values. RESULTS: Following autoxidation in ferrous HbO2, it was evident that formation of hemichrome, which tends to precipitate, occurred at various stages during the course of the autoxidation reaction namely at initial, intermediate or final stages, depending on temperature and pH of the solution. By varying temperature of the solution from 35 to 55 degrees C and pH from 4.5 to 10.5, it is shown here that HbO2 exhibits high susceptibility for hemichrome formation and its occurrence is a function of pH, temperature and progress of autoxidation of HbO2. Unlike HbO2 and its separated haemoglobin chains, monomeric bovine heart myoglobin (MbO2) did not easily form hemichrome. CONCLUSION: These findings provide a clue on the crucial role of haemoglobin molecule for senescent cell recognition or homeostasis in the blood circulation.

Animals↗
PubMed2002

Watching ripples on crystals.

We present a new method for imaging surface phonon focusing and dispersion at frequencies up to 1 GHz that makes use of ultrafast optical excitation and detection. Animations of coherent surface phonon wave packets emanating from a point source on isotropic and anisotropic solids are obtained with micron lateral resolution. We resolve rounded-square shaped wave fronts on the (100) plane of LiF and discover isolated pockets of pseudosurface wave propagation with exceptionally high group velocity in the (001) plane of TeO(2). Surface phonon refraction and concentration in a minute gold pyramid is also revealed.

Journal Article↗
PubMed2002

Spatiotemporal mapping of surface acoustic waves in isotropic and anisotropic materials.

We demonstrate a new method for a real-time imaging of surface acoustic waves at frequencies up to 1 GHz with picosecond temporal and micron spatial resolutions using an ultrafast optical pump and probe technique combined with a common path interferometer. Using samples with isotropic or anisotropic substrates coated with metallic thin films, we observe the propagation of Rayleigh-like modes and surface-skimming bulk modes as well as resolving surface phonon focusing effects. In addition we image surface acoustic wave propagation in a laterally inhomogeneous sample.

Journal Article↗
PubMed2002

Mapping and control of atomic force on Si(1 1 1)square root(3) x square root(3)-Ag surface using noncontact atomic force microscope.

We demonstrated the possibility of measuring the three-dimensional force-related map with true atomic resolution between an Si tip and Si(1 1 1)square root(3) x square root(3)-Ag sample surface by measuring the tip-sample distance dependence of noncontact atomic force microscope (NC-AFM) image, i.e. atomically resolved atomic force spectroscopy. Furthermore, we demonstrated the possibility of controlling the interaction force between the atom on the tip apex and a sample atom of Si(1 1 1)square root(3) x square root(3)-Ag surface on an atomic scale by placing an Ag atom on the Si tip apex instead of Si atom.

Journal Article↗
PubMed2002

Correlation between optimal tacrolimus doses and the graft weight in living donor liver transplantation.

The optimal doses of tacrolimus (FK) needed to reach and maintain a target blood level vary among cases of living donor liver transplantation (LDLT). One hundred and twenty four LDLTs in 122 patients were included in this study. Tacrolimus was administered by continuous intravenous infusion at a rate of 2.5 microg/kg/h just after the operation. The time needed to reach the target blood level and the dose needed to maintain this level for 1 week (17-18 ng/mL) were defined as the initial duration (ID) and secondary dose (SD), respectively. In the first 100 LDLTs, the correlations between ID or SD and some clinical factors were examined and equations for predicting ID or SD were derived. In the latest 24 LDLTs, FK was administered using these equations and the actual and calculated ID and SD values were compared. A multiple regression analysis revealed that only the graft weight/recipient standard liver volume (GW/SLV) ratio (%) correlated with ID or SD. Stepwise regression analysis led to the equations ID (h) = 0.4 x GW/SLV ratio + 0.2; SD (microg/kg/h) = 0.02 x GW/SLV ratio - 0.4. Simple regression analysis revealed a significant correlation between the actual and calculated ID and SD values (p < 0.0001). Initial duration and SD can be estimated from equations using the GW/SLV ratio.

Adolescent↗
PubMed2002

CT imaging of intrabiliary growth of colorectal liver metastases: a comparison of pathological findings of resected specimens.

The objective of this study was to assess the usefulness of CT in the pre-operative evaluation of macroscopic intrabiliary tumour growth of colorectal liver metastases. 25 metastatic nodules of 18 patients who underwent an initial hepatectomy for colorectal liver metastasis were retrospectively evaluated. The CT appearance and pathological findings of the resected specimens were correlated. A number of unusual peritumoral features associated with intrabiliary tumour growth were detected by pre-operative CT. These were classified into three patterns: (1) thickened portal tract; (2) intrahepatic bile duct dilatation; and (3) a wedge-shaped area with enhancement. In 8 (32%) of the 25 nodules the portal tract was depicted as thicker than usual and these features were found proximal to the tumour in three instances, distal to the tumour in four instances, and both proximal and distal in one instance. All of the three intrabiliary tumours larger than 30 mm resulted in thickening of the portal tract. Intrahepatic bile duct dilatation was detected in association with 10 (40%) of 25 nodules. Bile duct dilatation was observed in more than one segment when intrabiliary tumour reached the hepatic hilus from the tumour. The presence of bile duct dilatation was not related to either the size of the tumour or the extent of intrabiliary tumour growth. An abnormally high density wedge-shaped area on contrast enhanced CT was another feature indicating intrabiliary tumour growth and was seen in association with four nodules. Such areas were seen in the liver parenchyma distal to the tumour on three occasions, or encompassing the tumour on one accasion. This wedge-shaped area appeared as a well demarcated dark red-brown region in the cut surface of the resected specimen. CT was useful for detecting the presence of intrabiliary tumour growth with these three patterns of radiological findings in patients with liver metastases from colorectal cancer

Aged↗