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Biomedical subjects

Hiroshi Oka

Publications and source records attributed to Hiroshi Oka.

At least 19 recordsLinked to original sources
PubMed2006

Quantitative assessment of tumour extraction from dermoscopy images and evaluation of computer-based extraction methods for an automatic melanoma diagnostic system.

The aims of this study were to provide a quantitative assessment of the tumour area extracted by dermatologists and to evaluate computer-based methods from dermoscopy images for refining a computer-based melanoma diagnostic system. Dermoscopic images of 188 Clark naevi, 56 Reed naevi and 75 melanomas were examined. Five dermatologists manually drew the border of each lesion with a tablet computer. The inter-observer variability was evaluated and the standard tumour area (STA) for each dermoscopy image was defined. Manual extractions by 10 non-medical individuals and by two computer-based methods were evaluated with STA-based assessment criteria: precision and recall. Our new computer-based method introduced the region-growing approach in order to yield results close to those obtained by dermatologists. The effectiveness of our extraction method with regard to diagnostic accuracy was evaluated. Two linear classifiers were built using the results of conventional and new computer-based tumour area extraction methods. The final diagnostic accuracy was evaluated by drawing the receiver operating curve (ROC) of each classifier, and the area under each ROC was evaluated. The standard deviations of the tumour area extracted by five dermatologists and 10 non-medical individuals were 8.9% and 10.7%, respectively. After assessment of the extraction results by dermatologists, the STA was defined as the area that was selected by more than two dermatologists. Dermatologists selected the melanoma area with statistically smaller divergence than that of Clark naevus or Reed naevus (P = 0.05). By contrast, non-medical individuals did not show this difference. Our new computer-based extraction algorithm showed superior performance (precision, 94.1%; recall, 95.3%) to the conventional thresholding method (precision, 99.5%; recall, 87.6%). These results indicate that our new algorithm extracted a tumour area close to that obtained by dermatologists and, in particular, the border part of the tumour was adequately extracted. With this refinement, the area under the ROC increased from 0.795 to 0.875 and the diagnostic accuracy showed an increase of approximately 20% in specificity when the sensitivity was 80%. It can be concluded that our computer-based tumour extraction algorithm extracted almost the same area as that obtained by dermatologists and provided improved computer-based diagnostic accuracy.

Algorithms↗
PubMed2006

Abnormal lamellar granules in a case of CHILD syndrome.

BACKGROUND: A 32-year-old female had cutaneous and musculoskeletal changes consistent with congenital hemidysplasia with ichthyosiform erythroderma and limb defects (CHILD) syndrome. She was born with the dysplastic, shortened right-sided arm and leg. Erythematous, hyperkeratotic lesion occurred on the trunk initially and extended to the right-sided arm and leg. Almost all area of her right-side body except the head and neck was covered by the erythematous lesion with yellow waxy scales, and the distal end of the rudimentary leg showed a verrucous appearance. METHODS AND RESULTS: The histology shared many features with verruciform xanthoma. Electron microscopy revealed vesicular structures in the intercellular spaces of the stratum corneum and vacuoles or vesicular structures in upper prickle cell layer. Some of them can be recognized as abnormal lamellar granules. Within the foamy cells in the papillary dermis, large vacuoles were found. CONCLUSION: These findings suggested that abnormal lipid metabolism involving lamellar granules may be responsible to the skin lesion of CHILD syndrome.

Abnormalities, Multiple↗
PubMed2005

Cutaneous type pemphigus vulgaris: a rare clinical phenotype of pemphigus.

Pemphigus is an autoimmune blistering disease of the skin, mucous membranes, or both. There are two main categories of pemphigus: pemphigus foliaceus (PF) and pemphigus vulgaris (PV). PV is further subdivided into mucosal dominant and mucocutaneous types, according to the extent of cutaneous lesions. These classes of pemphigus have distinct histopathologic and serologic findings, with most cases falling into these subtypes. We report 4 cases that clinically showed blisters and erosions in the skin only, without mucosal involvement. Histologic examination of cutaneous lesions demonstrated suprabasilar acantholysis, a typical finding for PV. These patients had predominant anti-desmoglein 1 (Dsg1) IgG autoantibodies as well as anti-Dsg3 IgG autoantibodies, as determined by enzyme-linked immunosorbent assay. The desmoglein compensation theory posits that this rare phenotype can be produced by pathogenically weak anti-Dsg3 IgG in the presence of potent anti-Dsg1 IgG autoantibodies. Thus, cutaneous type PV without apparent mucosal involvement is observed as a rare clinical and histologic expression of pemphigus. This expression can be a transient phenotype that may develop from, or evolve into, other subtypes of pemphigus.

Autoantibodies↗
PubMed2005

Relationship between anxiety and thyroid function in patients with panic disorder.

The aim of this study was to investigate correlations between thyroid function and severity of anxiety or panic attacks in patients with panic disorder. The authors examined 66 out-patients with panic disorder (medicated, n=41; non-medicated, n=25), and measured their free thriiodothyronine (T3), free thyroxine (T4) and thyroid-stimulating hormone (TSH) levels. Significant correlations between the thyroid hormone levels and clinical features were observed in the non-medicated patients. The more severe current panic attacks were, the higher the TSH levels were. In addition, severity of anxiety correlated negatively with free T4 levels. In this study, we discuss relationship between thyroid function and the clinical severity or features of panic disorder.

Adolescent↗
PubMed2005

In vivo ultrastructural localization of the desmoglein 3 adhesive interface to the desmosome mid-line.

Desmoglein (Dsg) is a cadherin cell-cell adhesion molecule located in desmosomes and its precise mechanism for cell-cell adhesion still remains to be elucidated. Opposing cadherin molecules may adhere to the N-terminal EC1 domains, or the entire length of the extracellular (EC) domains may overlap. To solve this controversy, we performed immunoelectron microscopy to map the Dsg3 epitopes in desmosomes. Three different hybridoma cell lines producing anti-Dsg3 monoclonal antibodies (mAb) were intraperitoneally injected into immunodeficient mice and the precise ultrastructural location of bound IgG between the mucosal epithelial cells in vivo was statistically measured and analyzed. The binding site of the AK23 mAb that recognizes the N-terminal EC1 domain was localized to the electron-dense mid-line of desmosomes. The binding sites of AK7 and AK18, which recognize the C-terminal membrane proximal and middle portions of the EC domains, were localized to the desmosomal region proximal to the membrane and the region between the plasma membrane and the dense mid-line, respectively. These results indicate that the N-terminal regions of Dsg3 from opposing cells interact at the dense mid-line of desmosomes where EC1 overlaps.

Animals↗
PubMed2005

Panic disorder with and without agoraphobia: comorbidity within a half-year of the onset of panic disorder.

The present study was performed to compare the clinical features of patients with panic disorder with and without agoraphobia. The subjects were 233 outpatients with panic disorder (99 males and 134 females) diagnosed according to DSM-IV criteria. Sixty-three patients met the criteria for panic disorder without agoraphobia, and 170 met the criteria for panic disorder with agoraphobia. Patients with agoraphobia showed a significantly longer duration of panic disorder and higher prevalence of generalized anxiety disorder. However, there were no significant differences in prevalence of major depressive episodes, in current severity of panic attacks, or in gender ratio between the two groups. The second aim of the present study was to investigate the effects of onset age and sex differences on the development of agoraphobia within a half-year. The subjects were divided into two groups according to their self-report: patients who did or did not develop agoraphobia within 24 weeks of onset of panic disorder. A total of 40.6% of the patients developed agoraphobia within 24 weeks of the onset of panic disorder, and onset age and sex differences had no robust effect on the development of agoraphobia within 24 weeks.

Adult↗
PubMed2005

Systemic sclerosis with unusual panniculitis and overlying discoid lupus erythematosus-like lesions.

A 33-year-old men presented with systemic sclerosis accompanied by both unusual panniculitis and overlying discoid lupus erythematosus (DLE)-like skin changes on the left buttock. The lesion did not completely match either lupus erythematosus profundus or morphea profunda but featured clinical and pathological findings halfway between the two entities. No case report of co-existence of systemic sclerosis and morphea profunda was found in the literature, but there are three case reports of patients with systemic sclerosis and lupus erythematosus profundus. One of the three cases had DLE-like changes on the surface of the lesion, a clinical picture similar to our case. We speculated that the DLE-like changes in the overlying skin were due to local tissue ischemia. The accompanying panniculitis in our case was considered to be unique and somehow different from morphea profunda or lupus erythematosus profundus.

Adult↗
PubMed2005

EEG coherence analysis in never-medicated patients with panic disorder.

To investigate the functional abnormalities in the central nervous system (CNS) of patients with panic disorder (PD), we compared the electroencephalography (EEG) coherence values in 18 never-medicated PD patients with those in age-matched normal control subjects, and examined the relationships between EEG coherence values and both the duration of disease and the severity of panic attacks. EEG data were recorded in the resting state. The PD patients had lower coherence values with significant differences in F3-F4, C3-C4, P3-P4, F7-T5, and F8-T6. There were positive correlations for the higher alpha band between coherence values and both the duration of disease and the severity of panic attacks. These findings provide further evidence that PD patients have a lower degree of inter-hemispheric functional connectivity in the frontal region and intra-hemispheric functional connectivity in the bilateral temporal region, and that chronic condition or frequent panic attacks in PD patients may be related to the pathophysiological CNS changes.

Adult↗
PubMed2004

Linear discriminant analysis of dermoscopic parameters for the differentiation of early melanomas from Clark naevi.

As a first step to develop a screening system for pigmented skin lesions, we performed digital discriminant analyses between early melanomas and Clark naevi. A total of 59 cases of melanoma, including 23 melanoma in situ and 36 thin invasive melanomas (Breslow thickness < or =0.75 mm), and 188 clinically equivocal, histopathologically diagnosed Clark naevi were used in our study. After calculating 62 mathematical variables related to the colour, texture, asymmetry and circularity based on the dermoscopic findings of the pigmented skin lesions, we performed multivariate stepwise discriminant analysis using these variables to differentiate melanomas from naevi. The sensitivities and specificities of our model were 94.4 and 98.4%, respectively, for discriminating between melanomas (Breslow thickness < or =0.75 mm) and Clark naevi, and 73.9 and 85.6%, respectively, for discriminating between melanoma in situ and Clark naevi. Our algorithm accurately discriminated invasive melanomas from Clark naevi, but not melanomas in situ from Clark naevi.

Dermatology↗
PubMed2004

Prevalence of Helicobacter pylori antibodies in long-term dialysis patients.

BACKGROUND: Helicobacter pylori has been reported to play an important role in the development of gastritis and gastric ulcer. METHODS: This study included 168 patients with end-stage renal disease (ESRD; 30 non-dialysis patients, 138 patients receiving dialysis; mean duration of dialysis: 57.3 +/- 61.7 months) and 138 control volunteers. We investigated the prevalence of H. pylori infection by measuring H. pylori antibody (IgG) levels. RESULTS: The prevalence of H. pylori infection was 62.3% in the control group, 53.3% in the non-dialysis patients, and 36.9% in the dialysis patients. The percentage decreased with a reduction of renal function. In addition, the proportion of H. pylori-positive patients decreased with the duration of dialysis, and the antibody titre was also significantly decreased. There was no association between long-term oral administration of H2RA (H2 receptor antagonist) and the incidence of H. pylori infection. CONCLUSION: Among dialysis patients, the proportion of H. pylori-positive patients was low. An aetiological factor other than H2RA agents was suggested. Renal failure or dialysis treatment may influence H. pylori infection.

Adult↗
PubMed2003

Renal preservation in low ectopic right renal artery reconstruction during abdominal aortic aneurysm repair: report of a case.

Renal hypothermia achieved using cold (4 degrees C) heparinized Ringer's lactate is an effective method of preventing renal compromise during abdominal aortic surgery. We present the case of a 62-year-old man with an abdominal aortic aneurysm (AAA), complicated by involvement of an ectopic right renal artery with a low abdominal aortic origin and passage across the ventral side of the inferior vena cava. The patient underwent AAA repair and right renal artery reconstruction using renal perfusion with cold heparinized Ringer's lactate, and no deterioration of renal function occurred.

Aortic Aneurysm, Abdominal↗
PubMed2003

Noninvasive quantitative measurement of tissue blood flow in hepatocellular carcinoma using xenon-enhanced computed tomography.

The aim of this study was to quantitatively measure tissue blood flow (TBF) in hepatocellular carcinoma (HCC) by a noninvasive method using xenon (Xe) inhalation/CT scans and to correlate the measured TBF with histological features. TBF was measured in HCC with xenon-enhanced CT (xenon/CT) in 20 patients. In 15 patients with HCC diagnosed as hypervascular tumors by conventional CT, TBF of the tumors was significantly higher than that of noncancerous liver tissue (151.1 +/- 20 vs 42.6 +/- 20 ml/min/100 g). Histologically, these tumors were diagnosed as moderately-to-poorly differentiated HCC. In contrast, in five patients with hypovascular HCC, TBF of HCC was almost comparable to that of the noncancerous regions (45.3 +/- 6 vs 48.3 +/- 6 ml/min/100 g). All these tumors were well-differentiated HCC. In conclusions, the measured values of TBF correlate with the clinicopathologic features of liver tumors and nontumorous liver tissue in patients with HCC.

Administration, Inhalation↗
PubMed2002

Intravascular extraction of permanent pacemaker leads.

PURPOSE: Cardiac leads that became infected, fail, or are otherwise problematic present difficulties in the management of patients. In this report, we assess our intravascular countertraction technique. METHOD: Between February 1990 and January 2001, 13 leads were removed from 11 patients using the intravascular countertraction technique. The reasons for lead extraction were pacemaker infection and lead dysfunction. RESULTS: In two of these patients, the ventricular leads could not be completely removed. The complete success rate was 85% and the overall success rate was 92%. There were no serious complications such as cardiac rupture, vein injury, or death, and there were no clinical signs of pulmonary embolism. In one of the patients whose ventricular leads could not be removed completely, the ventricular lead was stretched from its previous round shape, but tricuspid valve regurgitation did not occur during the 3-year follow-up period. In the other patient, the distal electrode was left in the subclavian vein. However, this residual distal electrode did not migrate, and there were no clinical signs of any recurrence of infection. CONCLUSIONS: The present study suggests that to remove leads successfully, the largest locking stylet that can be easily passed to the lead's tip through the coil lumen should be chosen in order to avoid valve injury, which can sometimes occur when a ventricular lead's locking stylet is left in the coil lumen.

Aged↗
PubMed2002

Percutaneous cardiopulmonary support for the treatment of right ventricular thrombus.

The management of patients with acute pulmonary embolism (PE) remains controversial, despite an improved understanding of its pathogenesis and diagnosis. Haemodynamic instability due to right ventricular failure and hypoxia following PE is associated with a high mortality rate. This report describes a case of a 22-year-old woman with leukaemia in which percutaneous cardiopulmonary support (PCPS) was used as an adjunct to thrombolytic therapy in the treatment of right ventricular thrombus with acute PE. The patient has since undergone regular follow-up on an outpatient basis without showing any recurrence of thromboembolism at 2 years postoperatively. This experience suggests that supportive PCPS may provide favourable clinical outcomes in high-risk patients with severe PE.

Adult↗
PubMed2002

Two cases of a free-floating ball thrombus in the left atrium.

A free-floating ball thrombus in the left atrium is an unusual occurrence that may cause fatal systemic emboli or left ventricular inflow obstruction, often resulting in sudden death. The first of 2 cases was a 59-year-old female with mitral stenosis and chronic atrial fibrillation who presented with severe dyspnea. Transthoracic echocardiography revealed a free-floating ball thrombus and emergency thrombectomy and mitral valve replacement were performed successfully. A second thrombus, which was not found at preoperative examination, was attached to the anterior mitral leaflet and may have been the source of the free-floating ball thrombus. The second case was a 79-year-old female with chronic renal failure who underwent mitral valve replacement 11 years prior to admission. She had been dependent on hemodialysis for 10 years, and had suffered several recent transient cerebral ischemic attacks. Computed tomography showed a ring-shaped, high-density area in the left atrium and transthoracic echocardiography revealed a floating ball thrombus in the left atrium. Thrombectomy was performed, but the patient died as a result of postoperative pneumonia 2 months later. Case 2 appears to be the first reported case of a ball thrombus in a hemodialysis patient who had previously undergone mitral valve replacement.

Aged↗
PubMed2002

[Clinical investigation of perforated duodenal ulcer--with special reference to the presence of Helicobacter pylori infection and rate of recurrence].

Perforated duodenal ulcer was clinically evaluated with respect to Helicobacter pylori infection and rate of recurrence in 38 ulcer patients perforated and 154 patients with non-perforated duodenal ulcer who visited our hospital in past 5 years and 6 months. The frequency of occurrence of H. pylori-positivity was 42.1% in patients with perforated duodenal ulcer, significantly lower than that of 92.9% in patients with non-perforated lesions. This result suggests that H. pylori is hardly involved in the development of perforated duodenal ulcer. The rate of recurrence was significantly lower for perforated duodenal ulcer than for non-perforated ulcer. In particular, perforated duodenal ulcer did not recur in the group on maintenance therapy with H2-recepter antagonists. Maintenance therapy using inhibitors of gastric acid secretion seems effective for the prevention of recurrence of perforated duodenal ulcer.

Adult↗
PubMed2002

[Refraction-contrast bone imaging using synchrotron radiation].

The X-ray refraction-contrast imaging using synchrotron radiation with some X-ray energies is successfully performed at B120B2 of SPring-8. The refraction-contrast images of bone samples such as human dried proximal phalanx, wrist, upper cervical vertebrae and sella turcica, and as mouse proximal femur, using the synchrotron X-ray are always better in image contrast and resolution than those of the absorption-contrast images using the synchrotron X-ray and/or the conventional X-ray tube. There is much likeness in the image contrast and resolution of trabeculae bone in the human dried proximal phalanx between X-ray energy of 30 keV at sample-to-film distance of 1m and those of 40, 50 keV at those of 4,5m, respectively. High-energy refraction-constrast imaging with suitable sample-to-film distance could reduce the exposure dose in human imaging. In the refraction-contrast imaging of human wrist, upper cervical vertebrae, sella turcica and mouse proximal femur using the synchrotoron X-ray, we can obtain better image contrast and resolution to correctly extract morphological information for diagnosis corresponding to each of the clinical field than those of the absorption-contrast images.

Animals↗