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Biomedical subjects

Keiko Koyama

Publications and source records attributed to Keiko Koyama.

8 recordsLinked to original sources
PubMed2006

PET and PET/CT using 18F-FDG in the diagnosis and management of cancer patients.

Positron emission tomography (PET) using 2-(18)F-fluoro-2-deoxy-D-glucose (FDG), a radioactive derivative of glucose, is an advanced imaging tool, based on the increased glucose consumption of cancer cells. FDG-PET provides information that is not obtainable with other imaging modalities, and is very effective in the diagnosis and management of patients with various types of cancers. However, there are some limitations, such as low FDG uptake in some cancers, substantial FDG uptake in inflammatory cells, and the lack of anatomical information and poor imaging quality of PET. A recently developed integrated PET/computed tomography (CT) system, which combines a PET camera and CT scanner in a single session, has overcome these drawbacks by providing both anatomical and functional imaging at the same position. PET and/or PET/CT using FDG is clinically useful in the detection of cancer, the differentiation of malignant and benign lesions, the staging of cancer before therapy, and the assessment of cancer therapy, as well as for determining the recurrence after therapy of most cancers, including lung cancer, gastrointestinal cancer, breast cancer, and malignant lymphoma. PET/CT has become the new standard approach to imaging in the diagnosis and management of many cancer patients.

Breast Neoplasms↗
PubMed2006

Estimation of premorbid IQ in individuals with Alzheimer's disease using Japanese ideographic script (Kanji) compound words: Japanese version of National Adult Reading Test.

The National Adult Reading Test (NART) is widely used as a measure of premorbid IQ of the English-speaking patients with dementia. The purpose of the present study was to develop a Japanese version of the NART (JART), using 50 Japanese irregular words, all of which are Kanji (ideographic script) compound words. Reading performance based on JART and IQ as measured by the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was examined in a sample of 100 normal elderly (NE) persons and in 70 age-, sex-, and education-matched patients with Alzheimer's disease (AD). The NE group was randomly divided into the NE calculation group (n=50) and the NE validation group (n=50). Using the NE calculation group, a linear regression equation was obtained in which the observed full-scale IQ (FSIQ) was regressed on the reading errors of the JART. When the regressed equation computed from the NE calculation group was applied to the NE validation group, the predicted FSIQ adequately fit the observed FSIQ (R2=0.78). Further, independent t-tests showed that the JART-predicted IQs were not significantly different between the NE and AD groups, whereas the AD group performed worse in the observed IQs. The reading ability of Kanji compound words is well-preserved in Japanese patients with AD. The JART is a valid scale for evaluating premorbid IQ in patients with AD.

Aged↗
PubMed2005

Pulmonary vein morphology before and after segmental isolation in patients with atrial fibrillation.

BACKGROUND: The morphology of the pulmonary veins (PVs) before and after segmental isolation of the PVs has not been sufficiently characterized. METHODS AND RESULTS: Multi-slice computed tomography was performed before and 3 +/- 1 months after ablation in 30 patients with atrial fibrillation who underwent PV isolation. Before ablation, PV narrowing (> or =25% luminal reduction) was found in nine (8%) PVs. After ablation, de novo PV narrowing was found in 24 PVs (26%) and was detected only in the supero-inferior direction in 14 PVs (58%). The diameter reduction inside the PVs after ablation was greater in the supero-inferior direction (14 +/- 12%) than in the antero-posterior direction (9 +/- 13%; P < 0.0001). In the ablated PVs, the PV trunk was shorter than before ablation (P < 0.0001). The reduction in the diameters of both the PV ostium and the ablation site in the ablated PVs, as well as the diameter of the PV ostium in the nonablated PVs, correlated with the decrease in the left atrial diameter. Shortening of the PV trunk correlated with the severity of PV narrowing, but it was not related to the percent diameter reduction of the left atrium. PV narrowing before or after ablation did not result in any clinical consequences. CONCLUSIONS: PV narrowing is present in about 10% of PVs before ablation. Asymmetric luminal reduction and longitudinal shrinkage of the PV trunk occur after ablation. Reverse remodeling of the PV and contraction of the PV wall may contribute to the reduction in the PV diameter. PV morphology should be assessed with multi-directional views to avoid missing heterogeneous legions.

Analysis of Variance↗
PubMed2005

Three-dimensional visualization of the coronary venous system using multidetector row computed tomography.

BACKGROUND: This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of the coronary venous system (CVS) by multidetector row computed tomography (MDCT). METHODS AND RESULTS: A total of 70 patients underwent MDCT and for each patient, 6 data sets were created throughout the cardiac cycle. The number and location of coronary veins were evaluated in 3-dimensional images using the 6 data sets. The quality of all images reconstructed from the 6 data sets was too poor to evaluate the CVS in 6 patients (9%). In the remaining 64 patients (91%), the diameter of the CVS was usually greater in the images reconstructed from data acquired during systole than in those reconstructed from data acquired during diastole. However, artifacts were observed more often in images from systole than from diastole. The coronary sinus and middle cardiac vein were visible in all 64 patients. The left marginal and posterior veins also were identified in 54 (84%) and 60 patients (94%), respectively. CONCLUSIONS: MDCT can be used as a non-invasive modality for evaluating the CVS anatomy in most patients.

Adult↗
PubMed2003

Protective effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids against oxidative stress-induced DNA damage of rat liver in vivo.

The present study was undertaken to know the effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids (PUFA) on oxidative stress-induced DNA damage of rat liver in vivo. Male Wistar rats were fed a diet containing fish oil or safflower oil with high n-6 PUFA at 50 g/kg of diet and an equal amount of vitamin E at 59 mg/kg of diet for 6 weeks. Livers of rats fed fish oil were rich in n-3 PUFA, whereas those of rats fed safflower oil were rich in n-6 PUFA. Ferric nitrilotriacetate was intraperitoneally injected to induce oxidative stress. The degree of lipid peroxidation of the liver was assessed by the levels of phospholipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and the degree of oxidative DNA damage was assessed by comet type characterization in alkaline single-cell gel electrophoresis and 8-hydroxy-2'-deoxyguanosine levels. The levels of TBARS of the livers of the fish oil diet group increased to a greater extent than those of the safflower oil diet group, whereas the levels of the hydroperoxides of the livers of both diet groups increased to a similar extent. The vitamin E level of livers of the fish oil diet group was remarkably decreased. The degree of DNA damage of both diet groups was increased, but the increased level of the fish oil diet group was remarkably lower than that of the safflower oil diet group. The above results indicate that fish oil supplementation does not enhance but appears to protect against oxidative stress-induced DNA damage and suggest that lipid peroxidation does not enhance but lowers the DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Effect of supplementation of n-3 polyunsaturated fatty acids on oxidative stress-induced DNA damage of rat hepatocytes.

The effect of supplementation of n-3 polyunsaturated fatty acids (PUFA) on oxidative stress-induced DNA damage of rat hepatocytes was examined. Male Wistar rats were fed a diet containing safflower oil (control n-6 PUFA diet) or fish oil (n-3 PUFA diet) in 50 g/kg of dried diet and an equal amount of vitamin E in 59 mg/kg of dried diet for 6 weeks. The liver of rats fed safflower oil was rich in n-6 PUFA, whereas that of rats fed fish oil was rich in n-3 PUFA. Isolated hepatocytes were treated in vitro with ADP/Fe (II) ion or hydrogen peroxide at 37 degrees C for 30 min to induce oxidative stress. The degree of lipid peroxidation was assessed by the levels of phospholipid hydroperoxides and thiobarbituric acid-reactive substances. The degree of oxidative DNA damage was assessed based on comet-type characterization in alkaline single-cell gel electrophoresis and 8-hydroxy-deoxyguanosine levels. In both ADP/Fe(II) ion and hydrogen peroxide oxidation, the degree of lipid peroxidation of hepatocytes increased in both diet groups, and the level of increase in the fish oil diet group was slightly higher than that in the safflower oil diet group. In ADP/Fe(II) ion oxidation, the degree of DNA damage increased in both diet groups, but there were no significant differences in the level of increase. In contrast, in hydrogen peroxide oxidation, the degree of DNA damage increased in both diet, and the increase in the fish oil diet group was significantly lower than that in the safflower oil diet group. It is unlikely that an n-3 PUFA-rich diet enhances oxidative stress-induced hepatocyte DNA damage as compared with the control n-6 PUFA-rich diet.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Survey of dental hygienists and healthcare workers for microorganisms in the oral cavity.

Over 350 bacterial species are known to form communities on tooth surfaces in the oral cavity, and opportunistic pathogens are frequently isolated from samples taken from the oral cavities of immunocompromised hosts, as well as elderly people with poor oral hygiene. To confirm the correlation between the prevalence of opportunistic pathogens in the oral cavity and oral hygiene, dental plaque and saliva samples from 15 dental hygienists and 15 healthcare workers were investigated. No opportunistic pathogens were found in the samples from dental hygienists, however, they were isolated from 10 of the 15 healthcare workers (66.7%). The total amounts of Streptococcus sp. and Lactobacillus sp. were also significantly higher in the healthcare workers. The amount of Streptococcus mutans was also higher, although the difference was not significant. From our results, we concluded that the prevalence of opportunistic pathogens and cariogenic bacteria in the oral cavity may be reduced by proper oral hygiene measures.

Adult↗