Search PubMed⌕ Search

Biomedical subjects

Y Hama

Publications and source records attributed to Y Hama.

At least 37 records · Page 2Linked to original sources
PubMed2001

Geographic variation in the number of authors on scientific abstracts.

OBJECTIVE: To determine if there was statistically significant geographic variation in the number of authors on abstracts of the 1999 Radiological Society of North America (RSNA) Scientific Assembly. METHODS: Information on type of presentation, number of authors listed in each presentation and country of origin was obtained for 2450 abstracts from the 1999 RSNA Scientific Assembly (1292 for scientific sessions, 1158 for scientific exhibitions). RESULTS: In scientific sessions, there were significantly more multiauthor (> 6 authors) presentations from Japan (32%, p < 0.001) and Germany (19%, p = 0.004) than there were from North America (United States and Canada) (11%). There were also significantly more multiauthor scientific exhibitions from Japan (29%, p < 0.001) than from North America (9%). Overall, the percentages of multiauthor presentations from Japan (30%, p < 0.001) and Germany (18%, p < 0.001) were significantly higher than those from North America (10%). CONCLUSION: There seems to be significant geographic variation in the number of authors credited on scientific presentations.

Abstracting and Indexing↗
PubMed2001

Preassignment examination for personnel on Iwo Jima.

The Japan Maritime Self-Defense Force (JMSDF) requires all personnel assigned to Iwo Jima to undergo a preassignment medical examination. The efficacy and benefit of this mandatory examination has not been evaluated objectively in depth. Our purpose was to review the health status of JMSDF personnel assigned to Iwo Jima and to evaluate the correlation of the preassignment medical examination to their current health status for the study period. We divided the participants into two groups. Group Y was composed of JMSDF personnel receiving a preassignment medical examination, and group N was composed of those personnel who did not receive the examination. After the annual health examination, health status was evaluated using objective criteria. We found little statistically significant difference among group Y and group N participants. However, proportionally more patients currently receiving care for or diagnosed with hypertension, hyperuricemia, or severe obesity were identified as being members of group N than group Y. We have demonstrated that the preassignment medical examination may contribute to predicting the health status of potential Iwo Jima personnel and may contribute to controlling the cost of care associated with these specific diagnoses by limiting the assignment of at-risk personnel.

Adult↗
PubMed2001

Technetium Tc 99m DTPA galactosyl human serum albumin to measure changes in hepatic functional reserve after transcatheter arterial embolization of the liver.

OBJECTIVE: To describe the acute and subacute changes in hepatic functional reserve using technetium Tc 99m diethylenetriaminepentaacetic acid galactosyl human serum albumin (Tc-99m DTPA GSA) in patients with hepatocellular carcinoma and liver cirrhosis who had undergone transcatheter arterial embolization (TAE). METHODS: Sequential Tc-99m DTPA GSA hepatic scintigraphies were performed prospectively in 26 consecutive patients with hepatocellular carcinoma and liver cirrhosis approximately 1 week before, 2 days after and 1 month after TAE. Counts per 10 seconds of the heart region of interest on 3- and 15-min images and the liver region of interest on a 15-min image were calculated. RESULTS: Clearance index decreased (p < 0.001) and receptor index and modified receptor index increased 2 days after TAE (p < 0.001 and p = 0.004, respectively), but these changes did not persist 1 month later. CONCLUSION: This study has established an expected pattern of behaviour of the liver after TAE, which could be used to monitor progress of patients who undergo the procedure.

Aged↗
PubMed2000

Intrafractional tumor position stability during computed tomography (CT)-guided frameless stereotactic radiation therapy for lung or liver cancers with a fusion of CT and linear accelerator (FOCAL) unit.

PURPOSE: To evaluate intrafractional tumor position stability during computed tomography (CT)-guided frameless stereotactic radiation therapy (SRT) for lung or liver cancers, we checked repeated CT scanning, with a fusion of CT and linear accelerator (FOCAL) unit. METHODS AND MATERIALS: The FOCAL unit is a combination of a linear accelerator (Linac), CT scanner, X-ray simulator (X-S), and carbon table, and is designed to achieve CT-guided SRT with daily CT positioning followed by immediate irradiation while patients keep reduced shallow respirations. To evaluate intrafractional tumor position stability, 50 lung or liver lesions in 20 patients were checked by repeated CT scanning just before and after irradiation, and the obtained images were compared. RESULTS: There was no case with the intrafractional error judged to be greater than 10 mm. In 68% of cases, the intrafractional positioning errors were negligible (0-5 mm). CONCLUSIONS: Using the FOCAL unit, SRT for lung or liver cancers could be performed with intrafractional positioning errors not greater than 10 mm.

Equipment Design↗
PubMed2000

Releasing profiles of gene products from recombinant Escherichia coli in a high-voltage pulsed electric field.

Release of recombinant proteins from gene-engineered Escherichia coli by applying a pulsed electric field (PEF) to a cell suspension was studied. When E. coli/pNC1, which produces beta-glucosidase and accumulates it in cytoplasm, was exposed to PEF, the most effective release of this enzyme was achieved in the cell suspension of 5% glycine and 15% PEG solution under 10kV/cm and 280J/ml of a PEF in a needle-plate electrode chamber. However, the amount of released beta-glucosidase by PEF treatment was only 26% of that by ultrasonic treatment. On the other hand, alpha-amylase produced by E. coli/pHI301A and accumulated in the periplasmic space could be easily released by PEF treatment. When this recombinant E. coli was suspended in 0.9% NaCl and 10% PEG solution and exposed to 10kV/cm and 200J/ml of a PEF in a plate-plate electrode chamber, 89% of intracellular alpha-amylase with nine-times higher specific activity compared with that by ultrasonic treatment was released. The release tendency of cellobiohydrolase, produced by E. coli/pNB6 and accumulated in both the cytoplasm and periplasmic space, was intermediate between those of beta-glucosidase and alpha-amylase. In this case, 70% of cellobiohydrolase with 1.9-times higher specific activity compared with that by ultrasonic treatment could be released when E. coli/pNB6 was suspended in 15% PEG and 10kV/cm and 200J/ml of a PEF was applied in a needle-plate electrode chamber. These results indicated that PEF treatment could easily disrupt the outer membrane, but it was difficult to disrupt the cytoplasmic membrane simultaneously. Therefore, PEF treatment is useful for easy release of periplasmic protein with selectivity.

Journal Article↗
PubMed2000

The likely transformation of papillary thyroid carcinoma into anaplastic carcinoma during postoperative radioactive iodine-131 therapy: report of a case.

We report herein a case of papillary carcinoma which appeared to transform into anaplastic carcinoma during postoperative radioactive iodine-131 (131I) therapy. A 67-year-old man who was diagnosed as having papillary thyroid carcinoma with bilateral neck lymph node involvement and multiple lung metastases underwent total thyroidectomy prior to 131I therapy. Immediately after a second course of 131I therapy, the patient complained of right neck pain and swelling, and a biopsy of the swollen neck lymph node was taken. Histologic examination of this biopsy specimen revealed anaplastic carcinoma. With p53 immunohistochemical staining, both the primary tumor and the biopsy specimen were positive. We speculate that first, some DNA damage in tumor cells was induced by the initial 131I therapy, but neither DNA repair nor cell apoptosis occurred because the p53 gene was already mutated; then further DNA damage was induced by the second 131I therapy, leading to anaplastic transformation.

Aged↗
PubMed2000

Expression of vascular endothelial growth factor and angiogenesis in cardiac myxoma: a study of fifteen patients.

OBJECTIVE: To clarify the association between angiogenesis and the clinicopathologic features in cardiac myxoma, vascular endothelial growth factor expression in the myxoma was examined by using reverse transcriptase polymerase chain reaction and immunohistochemistry, and the microvessel density was determined by counting microvessels in the myxoma by using immunostaining for platelet endothelial cell adhesion molecule 1. METHODS: Seven fresh-frozen and 15 formalin-embedded tissues were analyzed by means of reverse transcriptase polymerase chain reaction and immunostaining for vascular endothelial growth factor, respectively. The microvessel density was measured in the 15 formalin-embedded tissues. Furthermore, immunostaining for proliferating cell nuclear antigen was performed, and the proliferating cell nuclear antigen-labeling index was calculated. RESULTS: All of the 7 analyzed myxomas were positive for vascular endothelial growth factor messenger RNA, as determined by means of reverse transcriptase polymerase chain reaction, whereas atrial septum and atrium tissues were negative. Positive immunohistochemical reaction for vascular endothelial growth factor was observed in the cells of all 15 myxomas. The size of myxomas with high vascular endothelial growth factor expression was smaller than that of myxomas with low vascular endothelial growth factor expression. The microvessel density in myxomas with high vascular endothelial growth factor expression was higher than that in myxomas with low vascular endothelial growth factor expression. There was an inverse correlation between the tumor size and the ratio of the microvessel density in the central part to the microvessel density in the peripheral part of myxomas. Furthermore, there was an inverse correlation between the proliferating cell nuclear antigen-labeling index and the tumor size, and the prolferating cell nuclear antigen-labeling index in myxomas with high vascular endothelial growth factor expression was higher than that in myxomas with low vascular endothelial growth factor expression. CONCLUSIONS: Cardiac myxomas produce vascular endothelial growth factor, which probably induces angiogenesis for tumor growth.

Adult↗
PubMed2000

Microcapsulated parathyroid tissue in vitro.

Ideally, microcapsules will make it possible to transplant parathyroid tissue for allo- and xenotransplantation in hypoparathyroid patients. In this study, parathyroid tissues capsulated by polyelectrolyte complex were evaluated in vitro. Hormone secretion ability was significantly (P < 0.001) greater in sediment than in supernatant. There was no difference in hormone secretion ability between the parathyroid tissue thawed at room temperature and the tissue thawed in a bath at 37 degrees C. Both non-capsulated and capsulated parathyroid tissues were incubated for three weeks. The ability of capsulated parathyroid to secrete hormones in vitro was reduced gradually and disappeared within three weeks. There are still several problems to be solved before the clinical application of parathyroid allotransplantation using microcapsulation.

Cryopreservation↗
PubMed2000

Clinicopathological characteristics of atypical cystic duct (ACD) of the breast: assessment of ACD as a precancerous lesion.

To clarify the clinicopathological features of an atypical cystic duct (ACD) as defined by Tsuchiya's criteria as a precancerous lesion of the breast, we used 200 whole mammary gland serial sections of breast cancer. Forty-four (22%) of the 200 breast cancer patients had ACD breast lesions. The frequency of patients with ACD increased in premenopausal women (P = 0.001). There was no correlation between the ACD-present group and the ACD-absent group for immunohistochemical status of the estrogen receptor (ER), progesterone receptor (PgR), p53, or c-erbB2; Ki-67 labeling index of cancer tissues; size of tumor, or lymph node metastases. A number of ACD lesions displayed continuity to cancer lesions. In 500 serial sections of a paraffin-embedded tissue of a ACD case at 3 microm intervals, an apparent transition from ACD into ductal carcinoma in situ was observed. Immunohistochemical analysis using alpha-smooth muscle actin showed that myoepithelial cells of ACD stained strongly, and their nuclei and cytoplasm were thinning. In 16 of the 44 (36%) ACD-present patients, carcinoma cells stained positive for p53. Within those 16 cases, 12 cases (75%) were positive for p53 in ACD lesions. There was a significant correlation between the expression of p53 protein in malignant cells and ACD (P = 0.001). All 44 ACD lesions had no staining of c-erbB2, regardless of staining in malignant lesions. The mean Ki-67 labeling index of ACD lesions was low (0.3%), suggesting that ACD had a low proliferative rate. We suggest that ACD is the precancerous breast lesion because of a histologic continuum between ACD and malignancy, and because of p53 protein expression in ACD.

Adult↗
PubMed2000

Clinical recurrence of papillary thyroid cancer in the remnant lobe.

OBJECTIVE: To find out which factors predict recurrence of cancer in the remnant after unilateral thyroid lobectomy for patients with papillary cancer. DESIGN: Retrospective study. SETTING: Teaching hospital, Japan. SUBJECTS: One hundred thirty-three patients with a clinically solitary papillary thyroid cancer who had unilateral lobectomy for the primary disease between 1966 and 1990 and were followed up for more than 60 months. Twelve patients had developed recurrences in the remnant gland by the time of the second operation and 121 patients had not as judged by a second operation, an ultrasound examination, or by palpation. RESULT: The primary tumour size in those who developed recurrences was significantly larger than in those who did not (p < 0.0001), and clinical signs of regional lymph node involvement or distant metastases were also significantly more common (p = 0.006). No patient died of their cancer. CONCLUSION: Size of the primary tumour is an important prognostic factor for recurrence of solitary papillary thyroid cancer in the remnant after unilateral lobectomy. Such recurrences are unlikely to be lethal.

Adolescent↗
PubMed1999

Tumor Marker Levels Elevate False-Positively in Postsurgical Breast Cancer Patients with High sGPT Levels or with Receiving Oral 5-FU or Its Derivatives.

BACKGROUND: False elevation of tumor marker levels (TM) has been encountered in some postsurgical breast cancer patients. METHODS: We investigated 33 postsurgical breast cancer patients whose TM (CEA, CA15-3, NCC-ST-439, or BCA225) measured every 3 months, showed elevation 3 times in a row in a 6-month period, and in whom metastases were not detected at theend of the 6-month period. Nine patients developed recurrence within 36 months of the end of the 6-month period and 24 patients did not develop recurrence for more than 36 months after the end of the 6-month period. RESULTS: Seven patients who stopped treatment with oral 5-FU or its derivatives because of severe nausea and appetite loss did not develop recurrence. Normalization of TM (CEA, NCC-ST-439, or BCA225) manifested within 3 months of the interruption of the medication. Six patients who showed simultaneous increase in serum glutamic-pyruvic transaminase (sGPT) and TM (CEA or BCA225) in the initial 6months did not develop recurrence. Three of 6 patients did not take any anti-cancer drugs. Correlation coefficiencies of sGPT with CEA in 4 patients were 0.467, 0.569, 0.738, and 0.910 and those of sGPT with BCA225 in 3 patients were 0.663, 0.826, and 0.840. CONCLUSION: A false-positive increase in CEA, NCC-ST-439 or BCA225 might be caused by treatment with oral 5-FU or its derivatives. CEA or BCA225 elevates false-positively in patients with high sGPT levels.

Journal Article↗
PubMed1999

Preoperative embolization of meningiomas with pial supply: successful treatment of two cases.

BACKGROUND: The efficacy of preoperative embolization for hypervascular meningiomas fed by the pial branches of the internal carotid artery was evaluated. METHODS: Two cases of hypervascular meningiomas fed by the cortical branches of the internal carotid arteries are presented. In the first patient, the left anterior frontal internal artery was embolized with gelatin sponge (Gelfoam) as a preoperative treatment using a microcatheter. The tumor was totally resected with 1,000 ml of blood loss. In the second patient, the right sulcal artery was embolized with Gelfoam. The patient subsequently underwent surgical resection with 100 mL of blood loss. RESULTS: No neurological deficit appeared after the embolization or the surgery in either case. CONCLUSION: Preoperative embolization of hypervascular meningiomas, mainly fed by the cortical branches of the internal carotid arteries, may be possible and effective.

Carotid Artery, Internal↗
PubMed1999

Daily positioning accuracy of frameless stereotactic radiation therapy with a fusion of computed tomography and linear accelerator (focal) unit: evaluation of z-axis with a z-marker.

To evaluate quantitative positioning errors of frameless stereotactic radiation therapy with a fusion of computed tomography (CT) and linear accelerator unit, Z-type CT markers were attached to patients, and CT images were obtained before and after daily treatment. In 40 verification tests, geometrical errors were never more than 1 mm.

Brain Neoplasms↗
PubMed1999

Three-dimensional structure of the micro-blood vessels in thyroid tumors analyzed by immunohistochemistry coupled with image analysis.

The structure of micro-blood vessels, one of the most important factors influencing the tumor growth and tumor metastasis among histological types of thyroid malignancy, was analyzed immunochemically by staining tissues for platelet endothelial cell adhesion molecule-1 (PECAM-1). Human thyroid tumor tissue obtained at surgery, consisting of 18 cases of papillary carcinoma, 9 cases of follicular carcinoma, and 9 cases of anaplastic carcinoma were fixed in formalin solution, and paraffin sections were made. They were stained for PECAM-1 using the avidin-biotin complex (ABC) technique. The volume of the blood vessels and their three-dimensional (3D) structure were analyzed using an image analyzer. The volume ratios of blood vessels in thyroid tissues were: normal tissues, 1.10%; papillary carcinoma, 3.01%; follicular carcinoma, 8.13%; and anaplastic carcinoma, 0.91%. Ratios in malignant tumors were larger than in normal tissues, except for anaplastic carcinoma. The typical 3D structure of micro-blood vessels was histopathologically varied: branching tree-like blood vessels in papillary carcinomas; vessels of varied diameter surrounding follicle structure in follicular carcinomas; and simple and immature vessels in anaplastic carcinomas. The volume and 3D structure of micro-blood vessels in thyroid malignant tumors differed from those in normal tissues, and varied according to histological classification.

Adenocarcinoma, Follicular↗