Biomedical subjects

Jun Aoki

Publications and source records attributed to Jun Aoki.

At least 19 recordsLinked to original sources

PubMed2006

MR signal of the solid portion of pilocytic astrocytoma on T2-weighted images: is it useful for differentiation from medulloblastoma?

BACKGROUND AND PURPOSE: Although imaging features of cerebellar pilocytic astrocytoma and medulloblastoma have been described in many texts, original comparisons of magnetic resonance intensity between these two tumours are limited. In the present study the results of magnetic resonance imaging (MRI) were reviewed, focusing especially on the signal intensity of the solid portion of these neoplasms. METHODS: MR images of ten cerebellar pilocytic astrocytomas and ten medulloblastomas were reviewed. The signal intensities of the solid components were graded on a scale of 1 to 5, with higher scores indicating a signal intensity closer to that of water. The degree of enhancement, tumour cysts and peripheral oedema were evaluated on MR images. When the solid portion was heterogeneous (i.e. mixed signal intensity or degree of enhancement), the dominant area was selected for evaluation. RESULTS: On T2-weighted images, the signal intensity of the solid portion was equal to that of cerebrospinal fluid (CSF) in 50% of pilocytic astrocytomas. No medulloblastomas showed such hyperintensity. Most medulloblastomas (80%) were isointense to grey matter. On T1-weighted images, the signal intensity varied widely in pilocytic astrocytomas; however, all medulloblastomas were iso- or hypointense to grey matter. The MR enhancement pattern, cystic component and peripheral oedema all varied in both tumour types and no specific features were identified. CONCLUSION: A signal intensity of the solid portion isointense to CSF on T2-weighted images was characteristic of cerebellar pilocytic astrocytomas; this was not observed in medulloblastomas. Attention to T2-weighted imaging of the solid portions of a tumour is easy and helpful in differentiating between cerebellar pilocytic astrocytoma and medulloblastoma.

Adolescent↗

PubMed2005

Normal cranial nerves in the cavernous sinuses: contrast-enhanced three-dimensional constructive interference in the steady state MR imaging.

BACKGROUND AND PURPOSE: Three-dimensional (3D) constructive interference in steady state (CISS) MR imaging is useful for demonstrating cranial nerves (CNs) in the cistern. The purpose of this study was to evaluate normal CNs III, IV, V1, V2, and VI in the cavernous sinuses by using contrast-enhanced, three-dimensional (3D), Fourier transformation CISS MR imaging. METHODS: In 76 normal cavernous sinuses from 38 patients, detectability of CNs III-VI in the bilateral cavernous sinuses was evaluated by using contrast-enhanced 3D CISS MR imaging. In 40 cavernous sinuses from 20 patients, contrast-enhanced 3D CISS and contrast-enhanced T1-weighted MR imaging were compared for the detectability of these CNs. RESULTS: Each CN was separately demonstrated, and in 11 patients (29%), all CNs in the cavernous sinuses were identified on contrast-enhanced 3D CISS MR imaging. The images depicted the intracavernous segments of CNs III, IV, V1, V2, and VI in 76 (100%), 46 (61%), 70 (92%), 67 (88%), and 73 (96%) of the 76 sinuses, respectively. In comparison of imaging techniques, contrast-enhanced 3D CISS MR imaging had a detection rate significantly higher than that of enhanced T1-weighting imaging (P < .05) in all CNs except for CN III, which was detected in 100% of cases with both techniques. CONCLUSION: Contrast-enhanced 3D CISS MR imaging provides clear images of each CN in the cavernous segment. This useful method may contribute to the diagnosis of diseases involving the cavernous sinuses, such as Tolosa-Hunt syndrome.

Adolescent↗

PubMed2005

Clinical background and its relation to results of percutaneous needle biopsy of suspected bone metastasis under guidance with CT fluoroscopy.

PURPOSE: To investigate the clinical background of needle biopsy of suspected bone metastasis under guidance with CT fluoroscopy. PATIENTS AND METHODS: During a 3-year period (from April 2000 to March 2003), 103 needle biopsies on 101 lesions of 90 patients were performed for pathological evaluation of suspected bone metastasis. The clinical course of these patients prior to biopsy and its relation to the biopsy results were retrospectively reviewed. RESULTS: Sixty-two patients (69% of total cases) were referred for biopsy from orthopedic surgeons, and 51 of these patients consulted orthopedic surgeons on the initial presentation. Malignancy was pathologically proved in 47 (76%) of the 62 orthopedic patients, and in 19 (68%) of the 28 patients referred from other clinicians. Thirteen (21%) of the orthopedic patients had a history of malignancy, while 22 (78%) of the non-orthopedic patients were cancer patients. Metastasis was pathologically proved in 23 (66%) of the 35 patients with a history of malignancy, while malignancy was pathologically proved in 43 (78%) of the 55 patients without known malignancy. Diagnostic accuracy of the needle bone biopsy was 96%, and its complication rate was 0.7%. CONCLUSION: In the era of CT fluoroscopy, needle biopsy for suspected bone metastasis was most frequently requested for the patients who consulted orthopedic surgeons for the occurrence of local bone pain as the initial symptom of unknown malignancy. Frequency of malignancy proved by the biopsy in those patients was as high as that in the cancer patients referred from other clinicians.

Adolescent↗

PubMed2004

Bone scintigraphic and CT evaluation of chondrosarcoma of the rib: correlation with histological grade in 6 cases.

OBJECTIVE: The objective of this study is to assess the value of CT and bone scintigraphic findings for grading of rib chondrosarcoma. METHODS: Included in this study were six cases of histologically proven chondrosarcoma of the rib, in which bone scintigraphy and/or CT was performed. Correlation of histologic grade (I-III), tumor size on CT, CT grading (modified Brown's system), the pattern (nodular or peripheral, presence or absence of extended uptake pattern) and the intensity (Simon and Kirchner's grade, 0-4) of scintigraphic uptake were assessed. RESULTS: CT grade was III, except for one case of dedifferentiated chondrosarcoma. Scintigraphic grade was 3 or 4 in all the cases. CONCLUSION: The patterns of CT and bone scintigraphic findings more likely reflect the size of the mass and ossification, and are not well correlated with the histological grading.

Adult↗

PubMed2004

Noninvasive determination of regional myocardial perfusion with first-pass magnetic resonance (MR) imaging.

RATIONALE AND OBJECTIVES: To develop a method to provide absolute values of regional myocardial perfusion by means of color maps, and to determine myocardial perfusion reserve using magnetic resonance imaging during the first pass of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). MATERIALS AND METHODS: The study population consisted of five patients with hypertrophic cardiomyopathy, two with dilated cardiomyopathy, four with coronary artery disease, and one with normal coronary arteries who presented with mildly abnormal electrocardiogram findings. For each heartbeat, six continuous slices were acquired during the first pass of Gd-DTPA (0.05 mmol/kg body weight) before and during adenosine triphosphate (ATP) **stress using an electrocardiogram-triggered fast low-angle shot (FLASH) sequence on a 1.5-T magnetic resonance unit. Myocardial perfusion images were created and displayed by means of a color scale. The parameters were calculated pixel by pixel, using the upslope method. Myocardial perfusion reserve was then calculated, as the quotient of myocardial perfusion during ATP stress and perfusion before ATP stress. RESULTS: Myocardial perfusion during ATP stress in patients with normal coronary arteries (n = 1) or after successful percutaneous coronary intervention (n = 2) was increased compared with that before ATP stress. However, the patients with coronary artery disease (n = 2) failed to show increased myocardial perfusion. The patients with hypertrophic cardiomyopathy showed increased myocardial perfusion during ATP stress, although two with dilated cardiomyopathy did not. CONCLUSION: Our new technique can provide absolute values of regional myocardial perfusion by means of color maps, and has potential for widespread use for evaluation of ischemic and other types of heart disease.

Adenosine Triphosphate↗

PubMed2004

Role of Nup98 in nuclear entry of human immunodeficiency virus type 1 cDNA.

Human immunodeficiency virus type 1 (HIV-1), like other lentiviruses, can infect non-dividing cells. The lentiviruses are most likely to have evolved a nuclear import strategy to import HIV-1 cDNA and viral protein complex through the nuclear pore complex (NPC) formed by nucleoporin proteins (Nup). In this study, we found that synthesis of integrated and 2LTR but not full-length form of HIV-1 cDNA was clearly impaired in culture via transduction of vesicular stomatitis virus matrix protein (VSV M), an inhibitor protein, through binding to the phenylalanine-glycine (FG) repeat region of Nup98. The impairment of synthesis of integrated and 2LTR DNA with VSV M was restored by ectopic overexpression of Nup98. A series of experiments using Nup98-depleted NPC by the small interfering RNA (siRNA) technique showed specific impairment of NPC structure and some functions, including nuclear import of HIV-1 cDNA. Our results suggest that Nup98 on the NPC specifically participates in the nuclear entry of HIV-1 cDNA following HIV-1 entry.

Active Transport, Cell Nucleus↗

PubMed2004

Quantitative perfusion map of malignant liver tumors, created from dynamic computed tomography data.

RATIONALE AND OBJECTIVES: To apply perfusion computed tomography (CT) technique to variable malignant liver tumors, and to define the usefulness of quantitative color mapping. MATERIALS AND METHODS: Perfusion CT images were created for 36 malignant liver tumors in 28 patients (age, 66.4 +/- 10.1 years; range, 48-85) with metastatic liver tumors (n = 17; nine colorectal carcinomas, eight other malignant tumors) and hepatocellular carcinomas (n = 11). A single-slice dynamic CT was performed after an intravenous bolus injection of 40 mL of contrast material (320 mgI/mL) with 8 mL/sec. The parameters were calculated pixel-by-pixel using maximum slope method, and quantitative maps of arterial and portal perfusion were created. In four patients who underwent transcatheter arterial chemoembolization, perfusion CT was performed before and after transcatheter arterial chemoembolization. RESULTS: In all patients, liver tumors were shown as hypervascular lesions on arterial perfusion CT. The average arterial perfusion value of the metastatic tumors from the colorectal carcinomas was 0.67 +/- 0.33 mL/min/mL, and that of hepatocellular carcinomas was 0.94 +/- 0.26 mL/min/mL (P = .03). The other metastatic tumors from various primary tumors showed a wide range (0.19-1.45 mL/min/mL) of arterial perfusion. Arterial perfusion of the liver tumors was obviously decreased after successful transcatheter arterial chemoembolization. In 12 of 15 tumors, in which portal perfusion CT images could be created, region-of-interest analysis showed no portal perfusion in the tumors. In two cases, decreased portal perfusion in the segments, which malignant tumors involved, was demonstrated. CONCLUSION: Perfusion CT can provide quantitative information about arterial and portal perfusion of liver tumors, combined with good anatomic detail in one image. This technique has a potential to evaluate the angiogenesis of liver tumors, to show secondary changes in perfusion, such as decreased portal perfusion in apparently normal liver adjacent to metastases, and to monitor the therapeutic response in vivo.

Aged↗

PubMed2004

Agonist-induced internalization of leukotriene B(4) receptor 1 requires G-protein-coupled receptor kinase 2 but not arrestins.

The leukotriene B(4) (LTB(4)) receptor (BLT1) becomes desensitized upon repeated agonist stimulation. Little is known, however, about BLT1 internalization, which follows desensitization in most G-protein-coupled receptors (GPCR). In the current study, transiently expressed BLT1 readily internalized, after LTB(4) stimulation, in RBL-2H3 cells that express high levels of endogenous GPCR kinase 2 (GRK2) but did not in COS-7 or human embryonic kidney (HEK) 293 cells, which do not overexpress GRK. The internalization of BLT1 could be blocked in RBL-2H3 cells by coexpressing dominant-negative (DN) GRK2 K220R and could be promoted in HEK293 cells by coexpressing wild-type (WT) GRK2. Coexpression of WT or DN nonvisual arrestins had no effect on BLT1 internalization. Moreover, upon stimulation with LTB(4), BLT1 did not induce arrestin-green fluorescence protein redistribution in either cell type, even in the presence of overexpressed GRK2. Coimmunoprecipitation experiments confirmed that BLT1 could associate with GRK2 but not with arrestins. A C-tail-truncated mutant of BLT1 lost the capacity to internalize and associate with GRK2 upon exposure to LTB(4), suggesting that the C-tail was required for receptor internalization and association with GRK2. Taken together, our results indicate that the C terminus of BLT1 plays a pivotal role in receptor internalization and GRK2 association. Moreover, ligand-induced BLT1 internalization is dependent on GRK2 but independent of arrestins. This may allow differential, cell-type-specific signaling in response to LTB(4), depending on GRK expression levels.

Animals↗

PubMed2004

A lentiviral cDNA library employing lambda recombination used to clone an inhibitor of human immunodeficiency virus type 1-induced cell death.

Expression cloning technology of cDNAs is a suitable tool for identifying novel functional properties of genes. Here, we generated a lentiviral cDNA library-expressing system for human T cells based on a site-specific recombination system of phage lambda for transferring cDNA libraries with a minimum loss of its complexity. The library-transduced CD4(+) T cells were challenged with wild-type human immunodeficiency virus type 1 (HIV-1), and the cells that acquired resistance to HIV-1-induced cytopathic effect (CPE) were selected. From these cells, CD14 was isolated and proved to inhibit the entry of HIV-1 and the HIV-1-induced CPE. This cloning system allows rapid identification of genes encoding novel properties in human T cells and probably other mammalian cells.

Apoptosis↗

PubMed2004

Pulmonary thromboembolism. Evaluating the indication and effect of a vena caval filter with indium-111-platelet scintigraphy.

A 63-year-old woman complained of chest pain and was referred to hospital where she was found to have left pleural effusion and swelling, local heat and edema of the right lower leg. Initial pulmonary perfusion scintigraphy demonstrated multiple defects and pulmonary thromboembolism (PTE) was confirmed during the anticoagulant and thrombolytic therapy against thrombophlebitis. A Greenfield filter was inserted in the inferior vena cava to prevent recurrence of PTE from the thrombosis that was resistant to therapy. In-111-labeled platelet scintigraphy (platelet scintigraphy) showed abnormal uptake of platelets in the chest, femoral veins and abdomen, which suggested active thrombus formation in those regions, including the filter, and a risk of recurrent PTE. Therefore, the thrombolytic therapy was terminated and the anticoagulant therapy intensified. A computed tomography (CT) scan revealed thrombus at the filter, which was markedly decreased 1 month later on platelet scintigraphy. Pulmonary ventilation and perfusion scintigraphy revealed remarkable improvement of the PTE. In this case, platelet scintigraphy complemented CT in demonstrating the activity and localization of the thrombus and can be used to evaluate the risk of recurrence during thrombolytic therapy after insertion of a filter.

Blood Platelets↗

PubMed2004

Serous surface papillary carcinoma of the peritoneum: clinical, radiologic, and pathologic findings in 11 patients.

OBJECTIVE: The purpose of our study was to describe the clinical, radiologic, and pathologic findings of serous surface papillary carcinoma of the peritoneum in 11 patients. CONCLUSION: Serous surface papillary carcinoma of the peritoneum should be included in the differential diagnosis when ascites, omental caking, and peritoneal nodules or enhancement are observed in a postmenopausal woman with or without ovarian enlargement.

Aged↗

PubMed2004

Effect of pouched reconstruction after total gastrectomy on ERCP and ENBD--report of two cases.

Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic nasobiliary drainage (ENBD) are well known to be useful but these procedures are rarely indicated in patients after total gastrectomy, because the endoscopic approach is more difficult in the patients with standard reconstructions such as Roux-en-y esophagojejunostomy after total gastrectomy. Gastric replacement with various enteric reservoirs after gastrectomy has been used to improve the postprandial symptoms and nutrition of patients after total gastrectomy. We have been performing jejunal pouch double tract reconstruction (JPD) after gastrectomy and the patients' postoperative course has been satisfactory. In this report, we describe two cases of biliary tract disorders after total gastrectomy. One was choledocholithiasis and the other was bile leakage after cholecystectomy. In each case, we performed ERCP, and treated with ENBD tube placement, and we obtained satisfactory results. We emphasize that ERCP and ENBD are also useful and easy procedures for biliary tract disease in postgastrectomy patients with JPD reconstruction as well as in patients who have not undergone intestinal reconstruction. The advantages of JPD reconstruction are not only improving the postprandial symptoms and the nutrition of patients after total gastrectomy, but that it provides an easy endoscopic approach to the papilla of Vater.

Aged↗

PubMed2003

Utility of FDG-PET in differential diagnosis of benign and malignant fractures in acute to subacute phase.

OBJECTIVE: To evaluate the usefulness of positron emission tomography with [fluorine-18] 2-deoxy-2-fluoro-D-glucose (FDG-PET) for early differential diagnosis of benign and malignant fractures. MATERIALS AND METHODS: Among 1,164 patients who had received FDG-PET between January 1999 and December 2000, 20 patients were found to have an acute fracture on review of clinical charts and/or radiologic images taken within one month before or after FDG-PET examination. The fractures were finally diagnosed by clinical follow up of at least five months duration. Standardized uptake values (SUV) for the benign and malignant bone lesions were calculated and compared. RESULTS: Ten of the 20 patients were finally diagnosed to have a benign fracture, nine patients to have a malignant fracture, and one patient to have both a benign and a malignant fracture at different locations. A statistically significant difference in the SUV was found between the benign group (SUV: 1.36 +/- 0.49) and the malignant group (SUV: 4.46 +/- 2.12) (p = 0.0006, the nonparametric Mann-Whitney U test). CONCLUSIONS: FDG-PET can be a useful method for early differentiation between acute benign and metastatic fractures. Our retrospective study indicates that an acute benign fracture itself does not show significant FDG uptake.

Aged↗

PubMed2003

High [18F] 2-fluoro-2-deoxy-D-glucose (FDG) uptake of adrenocortical adenoma showing subclinical Cushing's syndrome.

A 48-year-old woman with left adrenal tumor, which showed increased uptake of [18F] 2-fluoro-2-deoxy-D-glucose (FDG) was presented. Her adrenal tumor was incidentally discovered, although she had no remarkable illness, and her blood pressure was normal. Hormonal examination including dexamethason suppression test and diurnal variation in serum cortisol level confirmed preclinical Cushing's syndrome. CT, MRI and 131I-adosterol scintigraphy showed findings consistent with adenoma. FDG-PET revealed that tumor had standardized uptake value of 4.8, which was higher than usual benign tumors. Histological diagnosis of the resected adrenal tumor was adrenocortical adenoma without evidence of malignancy. Although the current literature showed that adenomas in general did not exhibit increased FDG uptake, adenoma in the present case with subclinical Cushing's syndrome showed intense uptake of FDG, suggesting FDG-PET could evaluate hormonal function of an adrenocortical adenoma in a completely asymptomatic normocortisolism patient.

Adrenal Cortex Neoplasms↗

PubMed2003

FDG-PET for evaluating musculoskeletal tumors: a review.

Positron-emission tomography (PET) can provide an in vivo method for evaluating metabolism and physiology in normal and diseased tissues. Clinical trials with [(18)F]2-deoxy-2-fluoro- d-glucose (FDG), the most commonly used radiolabeled tracer for PET imaging, have demonstrated increased accumulation of FDG in several cancer tissues. In this article, we introduce the basic principles of FDG-PET and review current knowledge about FDG-PET for evaluating musculoskeletal tumors. Recent reports and our own experience suggest that FDG-PET cannot be a screening method for differential diagnosis between benign and malignant musculoskeletal lesions, including many neoplasms originating from different tissues altogether. FDG-PET might not accurately reflect the malignant potential of musculoskeletal tumors, but rather might implicate cellular components included in the lesions. A high accumulation of FDG can be observed in histiocytic, fibroblastic, and some neurogenic lesions, regardless of whether they are benign or malignant. More specific uses of FDG-PET, such as grading, staging, and monitoring of musculoskeletal sarcomas, should be considered for each tumor of a different histologic subtype.

Bone Neoplasms↗

PubMed2003

The effect of fatty infiltration on the liver tissue enhancement during portal phase computed tomography.

RATIONALE AND OBJECTIVES: To correlate the presence of fatty liver and the enhancement value of liver tissue during portal phase computed tomography. MATERIALS AND METHODS: Liver tissue enhancements during portal phase computed tomography were measured in 16 fatty liver and 35 control patients. All patients intravenously received 100 mL of non-ionic contrast material (320 mg iodine/ mL) at a rate of 3 mL/second, and the image acquisition started at 70 seconds. Attenuation values were measured on the 80-second portal phase images and the corresponding unenhanced images, and the contrast enhancement value (HU) of the liver tissue was calculated. Adjusted enhancement values were also calculated with the following equation: adjusted enhancement value = enhancement value (HU)/[dose (grams of iodine)/body weight (kg)]. RESULTS: The contrast enhancement value was significantly reduced in the fatty liver patients compared with the normal controls (37.0 +/- 7.2 vs 49.8 +/- 12.0 HU; P < .0001). This difference was still significant in adjusted enhancement value (80.1 +/- 13.7 vs 93.6 +/- 23.0 HU kg g(-1); P = .01). CONCLUSION: The liver tissue with fatty infiltration was less enhanced than controls, probably because of decreased portal perfusion.

Case-Control Studies↗

PubMed2003

Contribution of the diagnostic test to the physician's diagnostic thinking: new method to evaluate the effect.

RATIONALE AND OBJECTIVES: The purpose of this study was to develop and test a method for evaluating the effect of diagnostic tests on physicians' diagnostic thinking. MATERIALS AND METHODS: The authors applied the method to data obtained in a previous study. The diagnoses of surgeons in the emergency department before and after contrast material-enhanced computed tomography (CT) and their certainty were collected from the cases of 125 adult patients with acute abdominal pain. When the pre- or post-CT diagnosis was not consistent with the final diagnosis, the diagnostic certainty reported by a physician was converted to a negative value (true diagnostic certainty). Change in true diagnostic certainty was calculated by subtracting the values for diagnostic certainty before CT from those after CT. RESULTS: In 118 cases, the change in true diagnostic certainty was positive, which indicates that the CT information was beneficial for the physician's diagnostic thinking. The true diagnostic certainty before CT was 32.9% +/- 57.6 (range: -90% to 100%; 95% confidence interval: 22.7%, 43.1%) and that after CT was 73.4% +/- 37.0 (range: -80% to 100%; 95% confidence interval: 66.8%, 80.0%; P < .0001). Thus, the increase in true diagnostic certainty was 40.5% +/- 58.8 (range: -160% to 170%; 95% confidence interval: 30.1%, 69.2%). CONCLUSION: This method may be useful for estimating the effect of diagnostic tests on physicians' diagnostic thinking in variable conditions.

Abdomen, Acute↗

PubMed2003

Brain microhemorrhages detected on T2*-weighted gradient-echo MR images.

BACKGROUND AND PURPOSE: Multifocal microhemorrhages have been reported to be commonly found in the brain of patients with systemic hypertension and spontaneous brain hemorrhage. The factors associated with these lesions detected on T2*-weighted gradient-echo images were examined to determine whether these lesions serve to indicate different types of microangiopathy and to predict a patient's risk for symptomatic hemorrhage. METHODS: The study population consisted of 2164 patients who underwent 2416 consecutive brain MR imaging studies performed during 3 years. The patients with intracerebral hemorrhages due to vascular malformations, neoplasms, trauma, or intracranial surgery and those with incomplete medical records were excluded; 2019 cases were analyzed. RESULTS: The overall incidence of microhemorrhages was 9.8%, predominantly in the lentiform nucleus (n = 96), thalamus (n = 88), and cortical-subcortical region (n = 93). Presence of microhemorrhages had the highest significant correlation with history of hemorrhagic stroke (P <.0001); advancing age, hypertension, and prominent white matter hyperintensity on T2-weighted images had the next highest significant correlation. Cortical-subcortical microhemorrhages were more frequently observed in patients who had previous lobar hemorrhagic stroke (P <.005). Among 139 patients with microhemorrhages who could be clinically followed up for more than 1 month, four (2.9%) had new hemorrhagic stroke. CONCLUSION: The presence of microhemorrhages may be not only a direct marker of bleeding-prone small-vessel diseases but also an indicator of different types of microangiopathy and a predictor of further hemorrhagic stroke.

Adult↗