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Biomedical subjects

Y Sugawara

Publications and source records attributed to Y Sugawara.

At least 19 recordsLinked to original sources
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↗
PubMed2002

Prediction of improvement in regional left ventricular function after coronary artery bypass grafting: quantitative stress-redistribution 201Tl imaging in detection of myocardial viability.

BACKGROUND: This study investigated the usefulness of quantitative assessment of Thallium-201 stress redistribution myocardial scintigraphy combined with quantitative assessment of regional left ventricular function using the centerline method for predicting of recovery regional left ventricular function following myocardial revascularization. METHODS: Twenty patients with chronic total obstruction of the proximal portion of left anterior descending artery and/or right coronary artery were studied. Percent Tl-uptake method was used to evaluate myocardial viability before CABG. Regional LV function was evaluated before and after CABG with the centerline method. The territory of LAD was defined by chords 10 to 58 and that of RCA was defined by chords 59 to 80 in the centerline method. The parameter of regional left ventricular function was the mean (SF-Av.)/SD of each LAD and RCA territory. RESULTS: In cases showing a % uptake value under 50%, the preoperative value of (SF-Av.)/SD was -3.18+/-0.74 and postoperative value was -2.63+/-0.8 1. The difference between these values was not significant. When the %uptake value over 50%, the preoperative value of (SF-Av.)/SD was -2.80+/-0.49 and the postoperative value was -2.27+/-0.28. The postoperative value was significantly higher than the preoperative value(p=0.007). CONCLUSIONS: Even in cases of severe left ventricular dysfunction, regional left ventricular function improved if the value of % uptake in the redistribution Thallium imaging was 50% or over. Quantitative analysis of myocardial scintigraphy combined with quantitative analysis of left ventriculography is a useful method for predicting recovery of regional left ventricular function following myocardial revascularization.

Aged↗
PubMed2001

Living-related liver transplantation for primary biliary cirrhosis.

BACKGROUND: The prognosis of patients with primary biliary cirrhosis has improved since the introduction of transplantation. However, there has been limited experience with living-related liver transplantation for primary biliary cirrhosis. PATIENTS AND METHODS: Between January 1996 and October 2000, 105 patients underwent living-related liver transplantation at the University of Tokyo Hospital. Eighteen of these patients with primary biliary cirrhosis were the subjects of this study. The risk scores in the conventional and updated Mayo models ranged from 5.9 to 11.6 and 6.9 to 13.7, respectively. RESULTS: The graft weight ranged from 330 to 533 g, corresponding to 33 to 55% of the recipient's standard liver volume. Two patients died of pneumonia, 1 died due to sepsis, and the remaining 15 patients survived. The risk scores for the conventional and updated Mayo models correlated well with the duration of hospitalization (P=0.01, R=0.67 for both). The scores of the dead patients by the two models were more than 10 and 12, respectively. The postoperative courses of all of the donors were uneventful. CONCLUSIONS: The risk score in the Mayo model adequately reflected the outcome of the patients. To achieve the best possible outcome, further therapeutic tactics are necessary for patients with conventional or updated Mayo risk scores of more than 10 or 12, respectively.

Adult↗
PubMed2001

Atomic resolution noncontact atomic force and scanning tunneling microscopy of TiO2(110)-(1 x 1) and - (1 x 2): simultaneous imaging of surface structures and electronic states.

We present simultaneous imaging of TiO2(110)-(1 x 1) and - (1 x 2) using noncontact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM). The surface topography was imaged under NC-AFM feedback, while the surface electronic states were imaged by STM. The image contrasts of NC-AFM and STM were antiphase in (1 x 1) and in phase in (1 x 2). The uppermost oxygen and Ti atoms underneath were, respectively, imaged by NC-AFM and STM. The NC-AFM image contrast was close to the true surface topography in (1 x 2), but reduced in (1 x 1).

Journal Article↗
PubMed2001

Phosphate decreases osteoclastogenesis in coculture of osteoblast and bone marrow.

Alkaline phosphatase (ALP) activity increases dramatically during osteoblast maturation, a phenomenon that is related to calcification of teeth and bone. Although the relation between ALP and calcification is widely known, there is a paucity of date relating ALP and osteoclast formation. Very recently, we showed that osteoblast maturation suppresses osteoclast formation. However, the relation between osteoblast maturation and osteoclastogenesis remains unclear. In the present study, we examined the effect of extracellular phosphate on osteoclastogenesis. As osteoblasts matured, osteoclast formation decreased, and ALP activity and inorganic phosphate in extracellular matrix increased. Inorganic phosphate in extracellular matrix and extracellular phosphate was suppressed osteoclast formation. These results suggest that phosphate released by ALP may be related not only to calcification but also to suppression of osteoclastogenesis.

Alkaline Phosphatase↗
PubMed2001

Congestion of right liver graft in living donor liver transplantation.

BACKGROUND: Left liver graft from a small donor will not meet the metabolic demands of a larger adult recipient. One solution to this problem is to use a right liver graft without a middle hepatic vein (MHV). However, the need for drainage from the MHV tributaries has not yet been described. METHODS: Five right liver grafts without a MHV were transplanted in patients including two hepatitis B virus-cirrhosis, two fulminant hepatic failure and one secondary biliary cirrhosis. The graft weight ranged from 650 to 1,000 g, corresponding to 48 to 83% of the standard liver volume of the recipients. RESULTS: Two of five recipients were complicated with severe congestion of the right median sector immediately after reperfusion, followed by prolonged massive ascites and severe liver dysfunction. One of the patients died of sepsis with progressive hepatic dysfunction 20 days after the operation. CONCLUSIONS: Preservation and reconstruction of the MHV tributaries is recommended to prevent congestion of the right liver graft without MHV.

Body Weight↗
PubMed2001

Twenty-four-hour Tl-201 delayed scan underestimates myocardial viability in patients with acute myocardial infarction after percutaneous transluminal coronary angioplasty.

BACKGROUND: Myocardial viability in area at risk of acute myocardial infarction (AMI) after reperfusion therapy may be underestimated by the 24-hour images due to reverse redistribution (r-RD). METHODS: Subjects were 37 AMI patients in whom Tc-99m pyrophosphate (PYP)/Tl-201 dual-isotope SPECT was positive. The 24-hour delayed scan was performed with only a Tl window. One month later, follow up rest Tl SPECT was performed to evaluate myocardial viability. In early (at PYP/Tl-201 dual-isotope SPECT), 24-hour, and one month follow up Tl studies, Tl uptake in the area of AMI was scored into four grades: 3 as normal to 0 as severely reduced. The scores were evaluated. RESULTS: Among the 37 AMI lesions, there were 16 r-RD, 3 RD, 16 fixed defect (FD) and 2 normal (positive PYP and normal Tl). Mean Tl scores were early; 1.4 +/- 1.1, 24-hr; 0.9 +/- 0.9 and one month; 1.3 +/- 1.1. The 24-hour Tl score was lower than the early and one month Tl scores (p < 0.01). CONCLUSION: Reverse redistribution is frequently observed in an area at risk where PYP SPECT was positive. Nuclear medicine physicians should be aware of the existence of frequent r-RD in Tl scan to avoid the underestimation of myocardial viability in the acute phase after PTCA.

Aged↗
PubMed2001

Initial experience with off-pump coronary artery bypass grafting.

Off-pump coronary artery bypass grafting (OPCAB) is clearly preferable for patients with extracardiac complications. The aim of this study was to evaluate the initial outcome of OPCAB, and its validity for patients with extracardiac complications. One hundred and fifty-seven consecutive coronary artery bypass graft (CABG) patients were divided into two groups: 30 OPCAB patients and 127 on-pump CABG patients. The early outcomes of the two groups were compared. Preoperatively, OPCAB patients had more extracardiac risk factors than on-pump CABG patients. There were no differences in age or cardiac function between the groups, but the off-pump group had a higher incidence of previous surgery, cerebrovascular disease, and renal failure. There were no differences in graft patency, stroke, or mortality between the two groups, even though the OPCAB patients had more risk factors than the on-pump patients. Our initial experience with OPCAB showed that it is acceptable for high-risk patients in view of the serious nature of their extracardiac condition.

Aged↗