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Masaharu Yoshikawa

Publications and source records attributed to Masaharu Yoshikawa.

At least 19 recordsLinked to original sources
PubMed2007

Contrast-enhanced three-dimensional fusion sonography of small liver metastases with pathologic correlation.

PURPOSE: To demonstrate that liver metastases with a diameter of < or =40 mm show characteristic features on three-dimensional (3D) fusion sonographic images and that these sonographic findings can be correlated with histopathologic features of surgical specimens. METHODS: Liver metastases measuring < or =40 mm were examined via contrast-enhanced 3D fusion sonography. The characteristic sonographic findings of 17 tumor nodules in 11 patients with a histopathologically confirmed diagnosis of liver metastases were investigated, and their correspondence to the pathologic features were examined in 12 resected nodules. RESULTS: On sonograms, central vessels were visualized in all 17 tumor nodules and peripheral vessels were visualized in 12 nodules. On histopathologic examination, the portal triad vessels corresponded to the central vessels and were located at the center of the tumors. A thin layer of peritumoral hepatocytes showing various changes was also observed, and a group of tiny vessels were seen running along this layer of cells. CONCLUSIONS: Liver metastases measuring 40 mm or less in diameter were characterized by the presence of both central and peripheral vessels on contrast-enhanced 3D fusion sonography. There was good correlation between sonographic and histopathologic findings.

Adult↗
PubMed2006

Multidetector helical CT plus superparamagnetic iron oxide-enhanced MR imaging for focal hepatic lesions in cirrhotic liver: a comparison with multi-phase CT during hepatic arteriography.

The aim of this study was to evaluate multidetector helical computed tomography (MDCT), superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging, and CT arterial portography (CTAP) and CT during hepatic arteriography (CTHA) for the detection and diagnosis of hepatocellular carcinomas (HCC). This included visual correlations of MDCT and SPIO-MR imaging in the detection of HCC using receiver operating characteristic (ROC) analysis. Twenty-five patients with 57 nodular HCCs were retrospectively analyzed. A total of 200 segments, including 49 segments with 57 HCCs, were reviewed independently by three observers. Each observer read four sets of images (set 1, MDCT; set 2, unenhanced and SPIO-enhanced MR images; set 3, combined MDCT and SPIO-enhanced MR images; set 4, combined CTAP and CTHA). The mean Az values representing the diagnostic accuracy for HCCs of sets 1, 2, 3, and 4 were 0.777, 0.814, 0.849, and 0.911, respectively, and there was no significant difference between sets 3 and 4. The sensitivity of set 4 was significantly higher than those of set 3 for all the lesions and for lesions 10 mm or smaller (p<0.05); however, for lesions larger than 10mm, the sensitivities of the two sets were similar. No significant difference in positive predictive value and specificity was observed between set 3 and set 4. Combined MDCT and SPIO-enhanced MR imaging may obviate the need for more invasive CTAP and CTHA for the pre-therapeutic evaluation of patients with HCC more than 10mm.

Carcinoma, Hepatocellular↗
PubMed2006

Relationship between therapeutic efficacy of arterial infusion chemotherapy and expression of P-glycoprotein and p53 protein in advanced hepatocellular carcinoma.

AIM: To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein (PGP) and p53 protein in advanced hepatocellular carcinoma (HCC). METHODS: The study was conducted on 41 patients with advanced HCC who were treated by repeated arterial infusion chemotherapy. Biopsy specimens from the tumor were collected before the start of treatment in all the patients, and the specimens were stored frozen until immunohistochemical staining, which was performed after the start of treatment, to detect PGP and p53 protein expressions. Twenty of the forty-one patients were treated with an anthracycline drug (epirubicin hydrochloride; anthracycline group), and the remaining 21 were treated with a non-anthracycline drug (mitoxantrone hydrochloride in 11 patients and carboplatin in 10 patients; non-anthracycline group). The relationship between the chemotherapeutic efficacy and the results of immunostaining were compared between the two groups. RESULTS: Before the start of the treatment, PGP-positive rate was 90.2% (strongly-positive, 36.6%) and p53 protein-positive rate was 34.1% (strongly-positive, 19.5%). In the anthracycline group, the response rate was 40.0%. The number of patients showing poor response to the treatment was significantly larger in the patients with strongly positive PGP expression (P=0.005), and their prognoses were poor (P=0.001). In the non-anthracycline group, the response rate was 42.9%, and there was no significant relationship between the chemotherapeutic drug efficacy and the PGP or p53 protein expression. When only the data from the 11 patients treated with anthraquinone drug, mitoxantrone, were analyzed, however, the number of patients who showed poor response to treatment was significantly higher among the p53-positive patients (P=0.012), irrespective of the survival outcome. CONCLUSION: The chemotherapeutic efficacy with an anthracycline drug for advanced HCC can be predicted by immunohistochemical analysis of PGP expression. Similarly, immunostaining to evaluate p53 protein may be useful to predict the response in patients treated with an anthraquinone drug.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Midterm results for endovascular stent grafts via median sternotomy for distal aortic arch aneurysm.

Dislocation or perigraft leakage is a major problem during the follow-up period for endovascular stent graft (EVG) implantation via median sternotomy for distal aortic arch aneurysm. Anchoring sutures have been applied for the prevention of these complications. Here, we evaluate the midterm results and the efficacy of anchoring sutures. There were 21 male and 2 female patients enrolled in the study with an average age of 70 years (59-83). Aneurysm types were 21 true aneurysms (13 fusiform, 8 saccular), 1 chronic dissection, and 1 penetrating aortic ulcer. Total arch replacement was performed in two patients and aortocoronary bypass grafting was combined in four patients. Anchoring sutures to fix the EVG via median sternotomy were applied for 11 recent patients. The average follow-up period was 44 (22-79) months. There were no operative mortalities, but one case of paraplegia, one of stroke, and two of temporary spinal cord dysfunction. Complications related to EVG via median sternotomy occurred in five patients who had not received anchoring sutures, but the 11 patients with anchoring sutures showed no EVG-related complications. A chronic type B dissection revealed impending rupture due to false lumen infection 1 year after operation and repeat surgery was performed. Stent dislocation occurred in four patients, two of whom required repeat surgery via left thoracotomy due to endoleakage 3 and 4 years after surgery. One died from aneurismal rupture 5 years after surgery. One required emergency graft replacement because of graft perforation 5 years after surgery. The proportion of patients free from EVG-related events at 5 years after surgery was 75%. Anchoring sutures (P = 0.0155) and a large aneurysm of more than 80 mm (P = 0.0190) were predictors of late EVG-related complications. There were five late deaths: two were from stroke, one from rupture, one from cancer, and one from multiple organ failure after repeat surgery. EVG shortens postoperative recovery with relatively lower mortality, but spinal cord injury is a complication occurring with a relatively high rate. Patients with large aneurysms are not good candidates for EVG implantation via median sternotomy Anchoring sutures to fix the EVG to the aortic wall should help prevent EVG-related events and improve the durability of EVG.

Aged↗
PubMed2006

Computational fluid dynamics analysis of the pediatric tiny centrifugal blood pump (TinyPump).

We have developed a tiny rotary centrifugal blood pump for the purpose of supporting circulation of children and infants. The pump is designed to provide a flow of 0.1-4.0 L/min against a head pressure of 50-120 mm Hg. The diameter of the impeller is 30 mm with six straight vanes. The impeller is supported by a hydrodynamic bearing at its center and rotated with a radial coupled magnetic driver. The bearing that supports rotation of the impeller of the tiny centrifugal blood pump is very critical to achieve durability, and clot-free and antihemolytic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify the secondary flow through the hydrodynamic bearing at the center of the impeller and investigated the effects of bearing clearance on shear stress to optimize hemolytic performance of the pump. Two types of bearing clearance (0.1 and 0.2 mm) were studied. The wall shear stress of the 0.1-mm bearing clearance was lower than that of 0.2-mm bearing clearance at 2 L/min and 3000 rpm. This was because the axial component of the shear rate significantly decreased due to the narrower clearance even though the circumferential component of the shear rate increased. Hemolysis tests showed that the normalized index of hemolysis was reduced to 0.0076 g/100 L when the bearing clearance was reduced to 0.1 mm. It was found that the CFD prediction supported the experimental trend. The CFD is a useful tool for optimization of the hydrodynamic bearing design of the centrifugal rotary blood pump to optimize the performance of the pump in terms of mechanical effect on blood cell elements, durability of the bearing, and antithrombogenic performance.

Biomedical Engineering↗
PubMed2006

Late mortality and morbidity in elderly patients with mechanical heart valves.

A retrospective study was performed in patients under and over 65 years old implanted with a mechanical valve, to compare late mortality and morbidity. Of 381 patients who underwent mechanical valve replacement at Nagoya University in the 1990s, 357 (11 hospital deaths and 13 lost to follow-up; 96.4% follow-up rate) were followed up for 7.9 +/- 3.3 years (2,811 patient-years). They were divided into two groups either side of 65 years of age at operation. The young and elderly patient groups contained 275 and 82 patients, respectively. The survival rate in the young group was 96.1% (95% confidence interval, 93.7%-98.5%) at 5 years and 92.0% (95% confidence interval, 88.3%-95.7%) at 10 years, which was significantly better than 88.0% (95% confidence interval, 80.6%-95.4%) at 5 years and 73.8% (95% confidence interval, 66.2%-85.4%) at 10 years in the elderly group. The two groups did not differ significantly in the incidence of thromboembolic events, bleeding events, endocarditis, or reoperation. We are also encouraged by the fact that mechanical valves are not a risk factor for late mortality or morbidity, even in elderly patients.

Age Factors↗
PubMed2005

A pilot approach for quantitative assessment of liver fibrosis using ultrasound: preliminary results in 79 cases.

BACKGROUND/AIMS: Ultrasound is noninvasive and useful to evaluate liver disease despite its operator dependency. This pilot study was conducted to quantitatively assess liver fibrosis using ultrasound. METHODS: Fibrosis extraction ratios (FER) (fiber volume/total volume) of ultrasound and histological images of 8 autopsy specimens were compared. We also compared FER of ultrasound images from clinical patients (n=79) with histological fibrosis stages. RESULTS: In the autopsy study, FER correlation coefficient between histological images and ultrasound images was 0.992. Regarding clinical patients, there was sufficient evidence to indicate differences in the distributions of FER for each fibrosis stage (Kruskal-Wallis test P<0.0001). With FER cut-off to distinguish > or =F2 from F0 and F1 defined as mean plus standard deviation of F0 and F1, sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were 62, 75, 78, 57%, and 2.47, respectively. Regarding HCV cohort (n=44), they were 55, 87, 89, 50%, and 4.14, respectively. Areas under receiver operating characteristic curves were 0.78, 0.79, 0.83 and 0.83 for > or =F1, > or =F2, > or =F3 and =F4, respectively. Regarding HCV cohort, they were 0.74, 0.71, 0.79 for > or =F2, > or =3 and =4, respectively. CONCLUSIONS: The FER method has great potential for diagnosing liver fibrosis using ultrasound.

Adult↗
PubMed2005

Early clinical results of St. Jude Medical Symmetry aortic connector.

An automated anastomosis device named St. Jude Medical symmetry aortic connector has been used worldwide for off-pump coronary artery bypass grafting. However, early graft obstruction was recently reported, and its predictors should be clarified. From April 2002 to March 2004, 38 patients in our institution underwent off-pump coronary artery bypass grafting using the St. Jude Medical Symmetry aortic connector for saphenous vein graft (SVG) procedures; measurement of intraoperative graft flow and postoperative coronary angiography was performed. Early SVG events occurred in 9 (24%) patients: 8 occlusion cases and 1 case of stenosis. Predictors of early SVG events were assessed from a comparative study. Univariate logistic regression identified hyperlipidemia as the only significant predictor of early SVG events (P = 0.02, odds ratio 7.78). Lower SVG flow rate and poor ejection fraction did not show statistical significance (P = 0.09, odds ratio 1.09 and P = 0.09, odds ratio 0.96). The SVG event rate was much higher for the left circumflex branch compared with other locations (31% vs. 9%, P = 0.03) and decreased with increasing aortic connector size (small, 32%; median, 14%; large, 0%). Multivariate analysis did not identify a predictor of SVG events. The aortic connector is associated with a high incidence of early SVG events. Patients should be cautiously selected and the procedure should not be used for left anterior descending coronary artery or culprit lesions.

Aged↗
PubMed2005

Thoracic aneurysm rupture due to graft perforation after endovascular stent-grafting via median sternotomy.

We performed emergency repeat surgery for aneurismal rupture due to graft perforation with mechanical stress of the Z stent in a kinking graft after frozen elephant trunk procedure. Graft kinking occurred due to cranial migration of the Z stent. It is important to prevent stent dislodgement in order to achieve long-term durability and reliability in the frozen elephant trunk procedure.

Aged↗
PubMed2005

Arch-first technique performed under hypothermic circulatory arrest with retrograde cerebral perfusion improves neurological outcomes for total arch replacement.

OBJECTIVE: From 1998, we have adopted the arch first technique (reconstruction of arch vessels first and distal anastomosis second) instead of the distal anastomosis first technique for total arch replacement. The aim is to reduce the period of deep hypothermic circulatory arrest and the retrograde cerebral perfusion time. We evaluate the surgical results of the arch first technique. METHODS: The arch first technique was used in 50 cases (38 male and 12 female), of average age 68 years, from 1998 to 2003. There were 33 true aneurysms and 10 chronic and seven acute type A dissections. Clinical results were evaluated and compared with the distal first technique used in 24 cases operated on between 1992 and 1998. These were 14 males and 10 females, with an average age of 68 years. There were 16 true aneurysms, and three chronic and five acute aortic dissections. RESULTS: For the arch first technique there is a significantly shorter circulatory arrest time (32 vs. 72min, P<0.0001), but similar body ischemic times (76 vs. 72min, N.S.). With the arch first technique, all but two patients awoke within 24h, with an average delay of 9.3h. In the distal first technique, two patients did not awaken and three patients showed delayed awakening, with an average awakening time of 24h. The arch first technique led to one hospital death (2%), due to residual aneurysm rupture. Reversible ischemic neurological deficit (RIND) was complicated in three cases (6%), but no stroke occurred during operation. In the distal first technique there were four strokes, one RIND and three hospital deaths (12.5%). The arch first technique gave a significantly lower intra-operative stroke rate (P=0.0030) and smaller hospital mortality (P=0.0615). The arch first technique led to five late deaths, with an 84.5% 3 year survival rate, and the distal first technique led to six late deaths with a 59.1% 3-year survival rate. CONCLUSIONS: The arch first technique is clearly superior to the conventional distal first technique in surgical mortality and morbidity regarding neurological outcome, and provides a higher survival rate and better quality of life. The arch first technique is an excellent method for total arch replacement.

Adult↗
PubMed2005

Percutaneous ethanol injection for small hepatocellular carcinoma: therapeutic efficacy based on 20-year observation.

BACKGROUND/AIMS: To evaluate the therapeutic efficacy of percutaneous ethanol injection (PEI) for patients with < or = 3 lesions of small (< or = 3 cm diameter) hepatocellular carcinoma (HCC). METHODS: PEI was applied to 270 patients with small HCC as the first-line treatment option during a 20-year period. RESULTS: (1) There was no treatment-related deaths, and only 2.2% of severe complications; (2) PEI induced a complete response of all HCCs according to CT evaluation performed within one month after the procedure, and the local recurrence rate at 3 years was 10%; (3) the overall 3- and 5-year survival rates after treatment were 81.6 and 60.3%, respectively, but the rates were higher, 87.3 and 78.3%, in Child A patients with a solitary tumor < or = 2 cm in diameter; (4) factors significantly influencing survival were liver function (P = 0.0033) and serum alpha-fetoprotein level (P = 0.0014), and (5) the recurrence rate at remote sites in the liver was lower in patients with HCC < or = 2 cm (P = 0.0395) and in those with a solitary HCC (P < 0.0001) according to Cox's proportional hazard model. (6) Radiofrequency ablation would not have been performed in approximately 25% of these patients. CONCLUSIONS: PEI is considered a reliable treatment for small HCC in terms of safety and efficacy.

Adult↗
PubMed2005

Large regenerative nodule perfused by the portal vein.

In a 42-year-old Japanese woman with esophageal varices, abdominal ultrasound (US) demonstrated a hyperechoic lesion 3 cm in diameter in segment 4 (S4). This nodular lesion had high intensity on T1-weighted magnetic resonance imaging (MRI), low intensity on T2, and very high intensity on superparamagnetic iron oxide (SPIO) enhanced MRI. Angiography showed sparse distribution of arterial branches and dense distribution of portal branches in S4. Meandering, thin arteries were seen in the peripheral area of the right lobe. The second branches of the portal vein were hardly visualized anywhere in the liver. Computed tomography arterioportography (CTAP) revealed portal blood flow dominance in this nodular lesion. There was no evidence of ischemic liver damage, such as thromboembolic episodes, laboratory data of liver damage, coagulation abnormalities etc. Therefore this abnormality was more likely to be caused by anomalous changes than thrombotic changes. Needle biopsy revealed no atypical cells. Two years later, the nodule size was reduced to 1.9 cm, showing its benign nature. Based on these findings, this lesion was classified as a new type of large regenerative nodule (LRN) associated with anomalies in the portal veins and arteries. This is the first report of an LRN of this size in which portal vein perfusion was dominant. Moreover, this lesion was difficult to differentiate from hepatocellular carcinoma (HCC) by imaging. Analysis of the images and pathological features of this case would contribute to a better understanding of the pathogenesis of nodular lesions of the liver.

Adult↗
PubMed2005

Natural history of a dilated ascending aorta after aortic valve replacement.

BACKGROUND: Little information is available regarding the incidence of aortic dissection or rupture in patients with a dilated ascending aorta after aortic valve replacement (AVR). The present clinical study aimed to demonstrate the incidence of aortic complications after AVR in patients with a dilated ascending aorta and to clarify those risk factors associated with the progression of a dilated ascending aorta or late aortic events. METHODS AND RESULTS: A total of 35 patients with a dilated ascending aorta at the time of AVR were enrolled. A dilated ascending aorta was defined as 40 mm or greater in diameter by preoperative computed tomography or operative findings. The baseline ascending aorta diameter ranged from 40 to 55 mm with a mean of 44.8+/-4.4 mm. There was a high frequency of bicuspid valve disease in patients with a dilated ascending aorta (57%). The mean follow-up interval was 8.1+/-3.5 years (range: 2.3-13). Aortic events occurred in 5 patients (aortic dissection in 1, rupture in 2, reoperation in 2) during the follow-up. One aortic dissection developed at a baseline aortic size of 42 mm, whereas 2 aortic ruptures occurred at baseline aortic sizes of 47 mm and 50 mm. There was no statistically significant univariate association between any of the patient clinical characteristics and late aortic events or ascending aortic progression. CONCLUSION: Although the clinical course of patients with a dilated ascending aorta is unpredictable, aortic events may occur even in patients with a baseline aortic diameter of <50 mm. Therefore, preventive aortic surgery at the time of AVR should be considered to prevent aortic dissection or rupture in patients with an even slightly dilated ascending aorta with a diameter of 40 to 50 mm, unless the patient has a high operative risk or older age.

Adolescent↗
PubMed2004

Immunohistochemical metallothionein expression in hepatocellular carcinoma: relation to tumor progression and chemoresistance to platinum agents.

BACKGROUND: Metallothionein (MT), which is known to detoxify heavy metal ions, is considered to serve as a mechanism of resistance to platinum complex compounds. In the present study, MT expression in hepatocellular carcinoma (HCC) was immunohistologically investigated to clarify its relationship to clinical background factors and responsiveness to anticancer drugs. METHODS: Specimens from 117 patients with HCC were immunohistologically studied, using a monoclonal anti-MT antibody. the percentage of MT-positive HCC (MT ratio) cells was determined, to evaluate the extent of staining with anti-MT antibody. Staining with an MT ratio of more than 50% was categorized as diffusely positive; an MT ratio of 5% to less than 50% was focally positive; and an MT ratio of less than 5% was negative. Twenty-two patients received repeated arterial infusion chemotherapy with carboplatin (CBDCA), a platinum-containing compound, and the MT expression was analyzed in relation to their chemotherapeutic response. RESULTS: The ratio of MT-positive cells in HCC decreased with the degree of histological differentiation and also decreased with higher tumor stage. In patients treated with CBDCA, the ratio of MT-positive cells in responders was significantly lower than that in non-responders. CONCLUSIONS: MT expression decreases with the degree of histological differentiation and decreases with increasing tumor stage in HCC. In addition, MT expression may lower the antitumor effect of CBDCA.

Antineoplastic Agents↗
PubMed2004

Real time 3-D echocardiography in cardiac surgery.

OBJECTIVE: Real time 3-D echocardiography provides real time live images of intracardiac anatomy. We evaluate its clinical application for intraoperative echocardiography. METHOD: The "xStream"3-D architecture designed with "xMatrix array" using approximately 3,000 transducer elements achieves live digital volume imaging in real time 3-D echocardiography (SONOS 7500, Philips Medical Systems, Inc.). Intraoperative echocardiography was performed in mitral (n = 14) and aortic valve diseases (n = 6), 4 heart anomaly, 4 aortic diseases and 15 normal anatomies. RESULTS: Heart valves were depicted via enface view. Simultaneous movement of leaflets and subvalvular apparatus can be observed. Prolapsed leaflets are easily detected and regurgitated jets are detected as 3-D color images. The four cardiac chambers were observed in their real shape and size. Septum defects were also depicted in real shape, size and position. Precise intracardiac anatomy was observed in cardiac anomalies. Information on the endothelium, intimal flap, entry, reentry and aortic wall character was provided and allowed for planning in aortic surgery. CONCLUSION: Live 3-D echocardiography provides excellent depiction of any cardiac and aortic anatomy in any direction and greatly enhances efficiencies in planning appropriate surgical procedures.

Cardiac Surgical Procedures↗
PubMed2004

Beating mitral valve replacement for a patient with porcelain aorta.

Beating mitral valve replacement was performed for mitral valve stenosis in a patient with a porcelain aorta after aortic valve replacement. The 77-year-old patient had developed heart failure several times. A chest computed tomographic scan revealed severe calcification on the ascending aorta and aortic arch. A cardiopulmonary bypass was established by bicaval drainage and aortic return after epiaortic echographic evaluation of the ascending aorta. The mitral valve was successfully replaced under a beating heart.

Aged↗
PubMed2004

Metal contents of liver parenchyma after percutaneous ethanol injection or radiofrequency ablation in patients with hepatocellular carcinoma before and after trientine hydrochloride therapy.

We administered trientine hydrochloride, a drug used in the treatment of Wilson's disease, to patients with hepatocellular carcinoma after radical treatment with percutaneous ethanol injection or radiofrequency ablation, and examined its effect on the reduction of liver-tissue copper content. We enrolled 24 patients with 3 or fewer primary lesions of Child class A or B hepatocellular carcinoma with diameters of 3 cm or less who had undergone radical treatment with percutaneous ethanol injection or radiofrequency ablation. Trientine hydrochloride was orally administered in a single daily dose of 250 mg to 12 patients before a meal (at fasting, group 1) or at a total daily dosage of 750 mg, divided into 3 doses, to 12 patients (group 2). This study was a randomized between-groups comparative study of 12 weeks' duration. We used the particle-induced x-ray-emission method to determine liver-tissue mineral content. Urine copper and serum mineral levels were also measured, and transaminase levels were examined. Liver-tissue copper content decreased significantly, to 160.1 microg/g dry weight, after treatment, compared with the pretreatment level of 306.8 microg/g dry weight (P <.05). We detected no significant difference in iron or zinc content before and after treatment. The copper content was significantly reduced after treatment in both groups (P <.05). The urine copper level was significantly increased after 1 week of treatment but decreased thereafter. Serum copper levels were significantly reduced after treatment (P <.01). We detected no significant difference in transaminase level before and after treatment. Iron-deficiency anemia in 1 patient after 12 weeks' treatment was the only adverse reaction, and it was improved by the administration of an iron product. We noted no other overt adverse reactions. In patients with hepatocellular carcinoma, trientine hydrochloride therapy may significantly reduce copper content in liver tissue.

Aged↗