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Biomedical subjects

M Kitamura

Publications and source records attributed to M Kitamura.

At least 199 records · Page 11Linked to original sources
PubMed1997

Contrast mapping and evaluation for electronic X-ray images on CRT display monitor.

Simple chest X rays on film are the most common type of image in medical diagnosis. However, amongst the various types of medical X-ray images, they require the highest level of display quality due to the fact that the body structures they capture on film have varying degrees of permeability to X rays. Conventional high-definition digital display technology has not always been able to match the quality of such film images. This has been a major impediment against progress toward the complete digitization of simple chest X rays. The intent of this paper is to examine that, when applied to medical diagnosis of chest X rays, super-high-definition (SHD) images (digital images with resolution exceeding that of HDTV) are capable of producing a level of quality of diagnostic accuracy on a par with conventional film images. We will start out by seeking out the overall transmission characteristics of a system that uses digital radiography and a film digitizer to digitize images. We will then derive gray-scale transform characteristics based on the luminance linear method for approximating, as closely as possible on a CRT, film images on a light box that have wide dynamic range and high luminance. Finally, we will present the results of image evaluation experiments using high-definition CRT monitors. These results indicate that conventional film images and those on super-high-definition CRT monitors have nearly the same quality. They will also show that the contrast mapping selected by radiologists and theoretical luminance linear characteristics were almost the same except in low-luminance regions. We will also discuss radiologists' comments on CRT monitors after they participated in the evaluation experiment.

Data Display↗
PubMed1997

Small cell carcinoma of the kidney: case report.

An 83-year-old female diagnosed with small cell carcinoma of the kidney is reported on. The clinical picture was similar to that seen with transitional cell carcinoma of the renal pelvis. A right nephroureterectomy was performed and a histological examination revealed similar morphological features to those of small cell carcinoma of the lung. Neuroendocrine differentiation was proven by a positive immunoreaction to neuron-specific enolase. A review of the literature indicated that in the urinary tract, most of the cases of small cell carcinoma occurred in the urinary bladder, with this case being the eleventh reported case of small cell carcinoma originating in the kidney. As with many of the other cases of small cell carcinoma of the urinary tract, this patient's tumor was associated with both adenomatous and squamous differentiation. The patient died 2 months after surgery, prior to any chemotherapy administration.

Aged↗
PubMed1997

Effective cross-circulation technique of venoarterial bypass for differential hypoxia condition.

We examined a new technique of cross-circulation (CC) venoarterial bypass (VAB) with femoral arterial perfusion and superior vena cava drainage through a long femoral venous cannula. Six adult mongrel dogs weighing 15 to 20 kg underwent the CC-VAB with oxygenation after introduction of respiratory failure (RF). The flow of the CC-VAB was maintained at half the level of the control cardiac output, and the hemodynamic parameters were monitored. To evaluate hypoxia in the upper body, the arterial partial pressure of oxygen (PaO2 [mm Hg]) in the carotid artery and the venous saturation of oxygen (SvO2 [%]) in the pulmonary artery were measured during control, RF, standard VAB, and CC-VAB conditions. The PaO2 decreased significantly after the introduction of RF (41.7 +/- 12.4), and it returned to normal levels only after CC-VAB (151.2 +/- 24.5, p < 0.05). The SvO2 during CC-VAB (98.6 +/- 2.1) was significantly higher than that during VAB without CC (53.5 +/- 3.4, p < 0.05). These results suggest that this cross-circulation technique could be applied to patients with differential hypoxia during femoral VAB with oxygenation or percutaneous cardiopulmonary support (PCPS).

Analysis of Variance↗
PubMed1997

Significant left ventricular unloading with transaortic catheter venting during venoarterial bypass.

Insufficient unloading of the left ventricle with blood stagnation is a main cause of unsuccessful left ventricular (LV) recovery during percutaneous cardiopulmonary support (PCPS). The purpose of this investigation was to evaluate the effectiveness of transaortic catheter venting (TACV) for LV unloading. Six adult mongrel dogs (mean weight 16.3 kg, range 14-20 kg) underwent venoarterial bypass (VAB) with TACV. Bypass flow ranged from 0.8-1.2 L/min, and TACV flow ranged from 160-240 ml/min. In addition to monitoring the standard hemodynamic parameters, the slope of the LV end-systolic pressure-volume relation (Emax) during transient occlusion of the inferior vena cava, the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the stroke work (SW), the LV pressure-volume area (PVA), and the slope of the SW end-diastolic volume relation, the preload recruitable stroke work (PRSW) were assessed by means of a microtip manometer and a conductance catheter. The LV contractility (Emax) and aortic elastance (Ea) were equivalent in the 2 groups with or without TACV (7.7 +/- 1.1 versus 8.4 +/- 1.5 mm Hg/ml and 8.2 +/- 1.4 versus 7.6 +/- 1.3 mm Hg/ml). Comparing the measurements for the baseline to those for VAB with TACV, the SW was significantly reduced, and the PVA/SW was increased by TACV (1,685 +/- 309 versus 867 +/- 188 x 10(-4) J, p < 0.05 and 1.32 +/- 0.03 versus 1.58 +/- 0.11, p < 0.05, respectively). Furthermore, the PRSW was gradually decreased from the baseline value to the value resulting from VAB with TACV (75 +/- 8 versus 44 +/- 3 x 10(-4) J/ml, p < 0.01). In comparison, the percent reduction of SW between VAB and VAB with TACV tended to be increased by TACV (23.2 +/- 7.2% versus 46.9 +/- 7.7%, p = 0.05). These results suggest that TACV might reduce LV work (SW and PRSW) and might increase the LV energetic charge. In conclusion, TACV would be an adjunctive technique to VAB or PCPS for patients with LV failure.

Angioplasty, Balloon, Coronary↗
PubMed1997

Echographic detection of latent severe thrombotic stenosis of the superior vena cava and innominate vein in patients with a pacemaker: integrated diagnosis using sonography, pulse Doppler, and color flow.

Thrombosis of the innominate vein and SVC is a serious complication in patients with pacemakers, inducing pulmonary embolism or SVC syndrome. Venography is the definitive method for its diagnosis; however, it is too invasive for related studies. The purpose of this study was to validate sonography, pulse Doppler, and color flow in detecting noninvasively innominate vein or SVC thrombosis in patients with pacemakers. In 53 patients with pacemakers, the 1 severe SVC stenosis and 18 severe innominate vein stenoses due to thrombosis were diagnosed by digital subtraction angiography. Sonography accurately showed the severe SVC stenosis due to thrombosis, but had limitations on the innominate vein thrombosis. Color flow demonstrated mosaic flow, indicating poststenotic turbulence due to stenosis of the innominate vein and SVC caused by thrombosis in 15 of 16 patients, and pulse Doppler disclosed absence of flow due to complete occlusion of the innominate vein in 2 of 2 patients. Sensitivity and specificity for detecting severe innominate vein stenosis due to thrombosis using combined color flow and pulse Doppler was 94% and 100%, respectively. In conclusion, sonography, pulse Doppler, and color flow allow accurate detection of severe innominate vein or SVC stenosis due to thrombosis, and are therefore useful for the follow-up of patients with a pacemaker.

Aged↗
PubMed1997

Construction of adenovirus vectors through Cre-lox recombination.

Two barriers prevent adenovirus-based vectors from having wide application. One is the difficulty of making new adenoviruses, and the second is the strong immunological reaction to viral proteins. Here we describe uses of Cre-lox recombination to overcome these problems. First, we demonstrate a simple method for constructing E1-substituted adenoviruses. Second, we demonstrate a method to construct adenovirus vectors carrying recombinant genes in place of all of the viral genes, so-called gutless adenovirus vectors. The pivotal feature in each method is the use of a negatively selected adenovirus named psi5. We engineered a cis-acting selection into psi5 by flanking its packaging site with loxP sites. When psi5 was grown in cells making a high level of Cre recombinase, the packaging site was deleted by recombination and the yield of psi5 was reduced to 5% of the wild-type level. To make a new E1-substituted virus, we used psi5 as a donor virus and recombined it with a shuttle vector via a loxP site. The resulting recombinant virus has a single loxP site next to the packaging site and therefore outgrows psi5 in the presence of Cre recombinase. To make a gutless virus, we used psi5 as a helper virus. The only viral sequences included in the gutless vector are those needed in cis for its replication and packaging. We found that a loxP site next to the packaging site of the gutless virus was necessary to neutralize homologous recombination between psi5 and the gutless viruses within their packaging domains.

Adenoviridae↗
PubMed1997

Hemorrhagic and nonhemorrhagic stroke: diagnosis with diffusion-weighted and T2-weighted echo-planar MR imaging.

PURPOSE: To determine if diffusion- and T2-weighted echo-planar magnetic resonance (MR) imaging can be used to detect acute hemorrhagic stroke and to differentiate hemorrhagic from nonhemorrhagic stroke. MATERIALS AND METHODS: A total of 118 examinations (diffusion- and T2-weighted MR imaging) in 19 patients with 27 nonhemorrhagic strokes and in six patients with seven hemorrhagic strokes were performed. The ratios of apparent diffusion coefficient and of signal intensity on T2-weighted MR images in lesions to those in contralateral control areas were calculated. RESULTS: Decreased ADC was shown in lesions of acute (0-3 days) hemorrhagic stroke, as well as in lesions of acute nonhemorrhagic stroke. Hypointense areas were seen on T2-weighted MR images in patients with acute hemorrhagic stroke, in contrast to normal to increased signal intensity in those with acute nonhemorrhagic stroke. Apparent diffusion coefficient tended to remain decreased in hemorrhagic stroke lesions even 100 days after onset, in contrast to the increased coefficient in nonhemorrhagic stroke lesions at the late chronic stage (31 days or older). CONCLUSION: Diffusion- and T2-weighted echo-planar MR imaging can be used to detect and distinguish between acute hemorrhagic and nonhemorrhagic stroke.

Acute Disease↗
PubMed1997

Unexpected protection of glomerular mesangial cells from oxidant-triggered apoptosis by bioflavonoid quercetin.

Bioflavonoid quercetin is known as an anti-cancer agent that induces apoptosis of tumor cells. Currently, however, little is understood about the effect of this drug on the function of normal cells. In this report, we address an unexpected, novel action of quercetin against apoptosis. Pretreatment with quercetin protected mesangial cells from hydrogen peroxide (H2O2)-induced apoptosis. A similar effect was observed in other cell types including LLC-PK1 epithelial cells and NRK49F fibroblasts. To explore the molecular mechanisms involved, we tested the effect of quercetin on c-Jun/activator protein-1 AP-1), the crucial mediator for H2O2-initiated apoptosis. Northern blot analysis revealed that quercetin suppressed the c-jun expression by H2O2. This was correlated with blunted activation of 12-O-tetradecanoylphorbol 13-acetate response element (TRE) in response to H2O2. These results suggested that quercetin inhibited apoptosis via intervention in the c-Jun/AP-1 pathway. To further investigate the action of quercetin, its effect on tyrosine kinases was studied. Immunoblot analysis revealed that H2O2 induced tyrosine phosphorylation. Quercetin inhibited this process in a dose-dependent manner. Inactivation of tyrosine kinases was an event upstream of c-Jun/AP-1, because tyrosine kinase inhibitors suppressed both activation of c-Jun/AP-1 and induction of apoptosis by H2O2. These findings elucidated the novel action of quercetin as an apoptosis inhibitor. This cytoprotective effect was found to be via suppression of the tyrosine kinase-c-Jun/AP-1 pathway triggered by oxidant stress.

Animals↗
PubMed1997

Quantitative evaluation of the rate of myocardial interstitial fibrosis using a personal computer.

We investigated the reliability and reproducibility of an image-analyzing system run on a personal computer for measurement of myocardial interstitial fibrosis. Measurements of myocardial interstitial fibrosis in right ventricular endomyocardial biopsies obtained from patients with hypertrophic cardiomyopathy determined by this image-analyzing system were compared with measurements determined by the point-counting method. We also investigated the correlation between measurements of interstitial fibrosis obtained by image analysis and biochemical measurements of myocardial levels of hydroxyproline in normal and cardiomyopathic hamsters. The intra- and interobserver variability were significantly lower for measurements obtained by the image-analyzing system than for measurements obtained by the point-counting system. Reproducibility was superior with the image-analyzing method. The rate of myocardial interstitial fibrosis determined by the computer image-analyzing method was positively correlated with the hydroxyproline measurement (r = 0.89). Our results suggest that an image-analyzing system using a personal computer provides reproducible results with a high level of reliability.

Adult↗
PubMed1997

Gene amplification of int-2 and erbB in human esophageal cancer: relationship to clinicopathological variables.

Gene amplification is a relatively frequent event in human malignant tumors and is believed to play an important role in tumor progression. The int-2 and erbB genes are amplified more frequently than any other genes in human esophageal cancer. In order to investigate the correlation between these two proto-oncogenes and the clinical behavior of esophageal cancer, we examined DNA amplification of int-2 and erbB and analyzed their relationship to clinicopathological variables. Genomic DNA was extracted from 21 esophageal squamous carcinomas and normal esophageal mucosa, as well as from 4 metastatic tumors. We used Southern blot analysis for detection of gene amplification. Amplification of int-2 was observed in 13 of 21 cases (62%) and in all the metastatic tumors (4/4; 100%). We found a significant correlation between amplification of int-2 and the length of the primary lesion. Amplification of erbB was detected in 3 of 18 patients (17%). All patients who showed amplification of erbB also demonstrated amplification of int-2. These results suggest that amplification of int-2 or neighboring genes on 11q may participate in tumor progression and metastasis in patients with esophageal squamous cancer.

Age Factors↗
PubMed1997

Hypertrophic obstructive cardiomyopathy with abnormalities of the mitral valve complex.

The mechanism of obstruction of the left ventricular outflow tract (LVOT) in hypertrophic obstructive cardiomyopathy (HOCM) is mainly due to dynamic systolic anterior motion (SAM) of the mitral valve. We report a case of HOCM with mitral regurgitation (MR) associated with complicated abnormalities of the mitral apparatus which contributed to a high pressure gradient through the LVOT. A small, 53-year-old woman was admitted for chest pain and palpitation. Examinations revealed asymmetric septal hypertrophy of the left ventricle, MR, SAM of the mitral valve and a high pressure gradient (108 mmHg) through the LVOT. Operative findings revealed an abnormally hypertrophied interventricular septum, an extensively thickened and enlarged anterior mitral leaflet (AML), malposition of the origin of the anterior papillary muscle arising closer to the aortic annulus than normal, and its direct insertion into the AML without any distinguishable chordae tendineae. The hypertrophied septum and the large and protruding AML appeared to obstruct the LVOT, resulting in a loss of subaortic clearance that was recovered after mitral valve replacement and myectomy. Pathology of the papillary muscle was characteristic of HOCM, showing disorganization and disarray of myocardial fibers, bizarre-shaped nuclei, and intercellular fibrosis, while those of the mitral leaflets negated both rheumatic changes and endocarditis.

Cardiomyopathy, Hypertrophic↗
PubMed1997

[A case of DVR with Nicks's procedure for active infective endocarditis with periannular abscess].

We successfully performed DVR with aortic annular reconstruction by Nick's procedure for a case of active infective endocarditis (IE) with perianular abscess. The patient was 26-year-old woman, who suffered from acute AR and MR due to active IE. At operation, a bicuspid aortic valve was noted with scattered vegetations. The periannular abscess extended from the aortic annulus to the anterior mitral leaflet on which there was a leaflet aneurysm. The complete debridement of infected lesions resulted in the defect of aortic annulus at the area of the aorto-mitral fibrous continuity. We reconstructed the aortic annulus by the equine pericardial patch and performed DVR, followed by the reconstruction of the aortic root by Nicks's procedure. After the operation the antibiotics had been administrated to the patient until CRP became completely negative. The patient was discharged from our hospital at 59 POD with no evidence of recurrence of IE. In such cases, we acknowledge the importance of as much complete debridement of infected lesions as possible and regard Nicks's procedure useful as one of the options for reconstruction of aortic root after debridement.

Abscess↗
PubMed1997

[Simultaneous tricuspid valve operation in patients undergoing aortic and mitral double valve replacement].

In triple valvular surgery, AVR+MVR+TVR or TVP, there are some problems around operation, because patients impaired cardiac function after a long history of the disease and some of them are reoperation cases. The sixty-five patients operated from May in 1980 to June in 1993 were examined. They were divided into two groups, group P and group R, depending upon procedure of tricuspid position. Group P consisted of 51 patients and group R of 14 patients. There were 22 (34%) reoperations. In group P, organic changes in tricuspid valve were mild, however in group R, there were commissural fusion in 8 patients, destruction of leaflet due to infectious endocarditis in one patient, and marked tricuspid annular dilatation in five patients. There was one early death in group R, no early death in group P. Actuarial survival rate at the 10th postoperative year was good as 81.6% in group P and 85.7% in group R. There were no significant differences in operative mortality and actuarial survival between group P and R.

Adult↗
PubMed1997

Remitting seronegative symmetrical synovitis with pitting edema associated with gastric carcinoma.

We report a case of remitting seronegative symmetrical synovitis with pitting edema (RS3PE syndrome) associated with gastric carcinoma in an 80-year-old woman who developed polyarthritis with marked pitting edema of the dorsa of both hands and feet 7 days after fiberscopic examination of the stomach. A mass lesion was identified and histology of the biopsy specimen revealed gastric carcinoma. Polyarthritis and edema were partially relieved by an intraarticular injection of corticosteroid. Shortly after resection of the gastric carcinoma, her symptoms and signs disappeared. She has been free of symptoms for 3 yrs without medication.

Adenocarcinoma↗
PubMed1997

[Aortic valve replacement with the Toronto stentless porcine valve in a patient with clipping for cerebral arterial aneurysm].

A 48-year-old man, who had a cerebral arterial aneurysm, was admitted in our institution for operation of aortic valve stenosis. At first, he underwent clipping for cerebral arterial aneurysm under precise management of his hemodynamic condition. After the clipping operation, we performed aortic valve replacement with the Toronto stentless porcine valve because no anticoagulant therapy was ideal for patient with cerebrovascular disease and larger effective orifice area was preferable for stenotic aortic annulus. By means of echocardiography, mean pressure gradient of the aoric valve decreased from 42 mmHg to 22 mmHg after the valve operation. He was discharged from the hospital on the 23rd postoperative day, and he has been doing well without thromboembolic events and bleeding complications for five postoperative months. This experience suggest that the Toronto stentless porcine valve might be one of the valve of choice for patients with aortic valve disease and cerebrovascular disease.

Aortic Valve Stenosis↗
PubMed1997

[Detection of pulsated blood flow by cine mode 3D angiography].

The phase contrast(PC) has an advantage to get an information about flow speed of blood along the gradient axis. The cine mode 3D-PC MRA was performed by a 1.5T clinical MR system(GE; Signa) using multi-slices gradient echo sequence with ECG gating and velocity-encoding gradient along three orthogonal axes. The cine mode 3D-PC data in three axes was constructed from 10 cardiac phases, respectively. The black and white cine mode 3D-PC MRA enabled to get an information of blood flow speed. The color MRA, in which flow direction was assigned with RGB colors, enabled to observe flow orientation of blood. Furthermore, the flow speed vector in each pixel showed a detail flow information in the intravascular space.

Basilar Artery↗