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Biomedical subjects

G Matsunaga

Publications and source records attributed to G Matsunaga.

17 recordsLinked to original sources
PubMed2006

Forced magnetic reconnection and field penetration of an externally applied rotating helical magnetic field in the TEXTOR tokamak.

The magnetic field penetration process into a magnetized plasma is of basic interest both for plasma physics and astrophysics. In this context special measurements on the field penetration and field amplification are performed by a Hall probe on the dynamic ergodic divertor (DED) on the TEXTOR tokamak and the data are interpreted by a two-fluid plasma model. It is observed that the growth of the forced magnetic reconnection by the rotating DED field is accompanied by a change of the plasma fluid rotation. The differential rotation frequency between the DED field and the plasma plays an important role in the process of the excitation of tearing modes. The momentum input from the rotating DED field to the plasma is interpreted by both a ponderomotive force at the rational surface and a radial electric field modified by an edge ergodization.

Journal Article↗
PubMed2005

Excitation of toroidicity-induced Alfvén eigenmodes by the electrodes inserted in a heliotron/torsatron plasma.

A novel method of exciting shear Alfvén waves using electrodes inserted in a plasma was developed for basic study of Alfvén eigenmodes in a heliotron/torsatron plasma. The electrodes can induce excitation current along the confinement field line, and generate magnetic perturbations perpendicular to the confinement field. By sweeping the frequency of the current in a cold plasma, the toroidicity-induced Alfvén eigenmode was resonantly excited at the predicted frequency and radial location. Plasma response to the applied magnetic perturbations indicates a fairly large damping rate caused by continuum damping.

Journal Article↗
PubMed2005

Toroidal plasma rotation induced by the dynamic ergodic divertor in the TEXTOR tokamak.

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always in the direction of the plasma current, even if the toroidal projection of the rotating magnetic field perturbation is in the opposite direction. The observed toroidal rotation direction is consistent with a radial electric field, generated by an enhanced electron transport in the ergodic layers near the resonances of the perturbation. This is an effect different from theoretical predictions, which assume a direct coupling between rotating perturbation and plasma to be the dominant effect of momentum transfer.

Journal Article↗
PubMed2000

Inward turbulent transport produced by positively sheared radial electric field in stellarators.

Inward turbulent particle transport observed in the rf heated plasma of the H-1 toroidal heliac is reproduced in the CHS heliotron/torsatron by generating a region of positive radial electric field shear (E'(r)>0) using electron cyclotron resonance heating of the plasma edge. Empirical condition of the radial reversal of the turbulent flux derived from two experiments indicates that the shear electric field might be universally responsible for the recorrelation of the density and plasma potential fluctuations leading to the inward transport.

Journal Article↗
PubMed1997

Correlations between p21 expression and clinicopathological findings, p53 gene and protein alterations, and survival in patients with endometrial carcinoma.

The p21 protein inhibits cyclin-dependent kinases and mediates cell-cycle arrest and cell differentiation. It is induced by wild-type p53, but not by mutant p53. This study of 75 patients with endometrial carcinoma investigates the relationship between p21 expression and the functional status of p53, and the usefulness of p21 as a prognostic marker. Correlations were determined between p21 immunoreactivity, p53 overexpression as examined by immunohistochemistry, p53 DNA mutations as examined by polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) analysis, and clinicopathological features, including the clinical outcome. Immunoreactivity for p21 and p53 mutations were detected in 47 (62.7 per cent), 37 (49 per cent), and 23 (31 per cent) patients, respectively. There were no significant correlations between the presence or absence of p21 immunoreactivity and p53 overexpression and DNA mutations. Survival curves revealed that patients with p53 overexpression tended to have a poorer prognosis than those without p53 overexpression (P = 0.104), that patients with p53 mutations had a significantly worse prognosis than those without mutations (P = 0.035), and that patients with p21 expression tended to have a better prognosis than those without p21 expression (P = 0.074). Immunohistochemical analysis of p21 was not useful for evaluating the functional status of p53 in patients with endometrial carcinoma. Both p21 expression and p53 abnormalities were considered as prognostic indicators in patients with endometrioid endometrial carcinoma.

Biomarkers, Tumor↗
PubMed1997

Aromatase in human bone tissue.

Peripheral aromatization of androgens exert estrogenic actions in many tissues. Recently in situ production of estrogens by aromatase was detected in human bone and cultured osteoblasts and has been proposed to participate in the maintenance of bone mass. We examined aromatase expression by immunohistochemistry and mRNA in situ hybridization in 16 cases of tibia (female 2 male, 14 female, 62 +/- 5.2 years old) and quantified the level of aromatase mRNA in 28 cases of rib, femur, and lumbar vertebrae (16 male, 12 female, 58.0 +/- 11.3 years old) by reverse transcriptase-polymerase chain reaction (RT-PCR) in order to study whether or not and in which cell types aromatase was expressed in human bone tissues. We also studied alternative use of multiple exons 1 of its gene and immunolocalization of type I 17 beta-hydroxysteroid dehydrogenase (HSD), which converts estrone produced by aromatase to estradiol. Strong aromatase immunoreactivity and mRNA hybridization as well as type I 17 beta-HSD immunoreactivity were detected in lining cells, osteoblasts, chondrocytes of articular cartilage, and adipocytes adjacent to bone trabeculae in all the cases examined. Amounts of aromatase mRNA varied greatly among the subjects (11.25 +/- 9.77, 0.61-42.84 attomol/ng of total RNA). The amount of aromatase expression was not correlated with age or gender of the subjects but positively correlated with the degree of osteroporotic changes evaluated by radiological findings of lumbar vertebrae. Analysis of multiple exons 1 revealed that 1b or fibroblast type was predominantly (23/26) utilized as a promoter of aromatase gene expression. These results demonstrated that aromatase is expressed widely in human bone tissue and may play important roles in maintenance of human bone tissue.

17-Hydroxysteroid Dehydrogenases↗
PubMed1997

Cost-effective analysis of mass screening for cervical cancer in Japan.

Cost-effectiveness analysis for cervical cancer screening in Japan was performed to estimate the cost per life-year saved by the screening; cost-effectiveness ratio (CER). The analysis was made using a simulation model to estimate long-term cost and effectiveness of the screening programs. CER of cervical cancer screening was estimated to be US$ 40,604 which was 2.4 times more expensive than that for gastric cancer screening but was about the same as that for colorectal cancer screening. It was within the range of cost-effectiveness of other cancer screening programs financed under the Health and Medical Services Law for the Aged in Japan. We performed sensitivity analysis on the following seven estimates, the screening charge, the sensitivity and the specificity of the screening test, the frequency of carcinoma in situ (CIS) among cases detected in the screening program, the initial cost and the terminal cost for patients with invasive cancer, and the incidence rate of cervical cancer. The sensitivity analysis demonstrated that the screening charge was the most influential factor on CER. CER was fairly stable under various assumptions on the accuracy of the screening test, the frequency of carcinoma in situ (CIS), the treatment cost for patient, and the incidence of cervical cancer. CER was less sensitive to the changes in incidence, even to as low as a 50% decrease of the current figure. Then if the incidence rate becomes 85% of the current figure in 2015, CER would be US$ 48,176 and it was suggested that the cervical cancer screening would remain reasonably cost-effective until the year 2015.

Adult↗
PubMed1997

Immunohistochemical study of Ki-67 and DNA topoisomerase II in human endometrium.

Topoisomerase II (topo II) separates the chromosomes at the end of mitosis, and its expression is limited mostly to the S-to-G2/M phases of the normal cell cycle. We examined the expression of topo II immunohistochemically in 56 specimens of the human endometrium that were retrieved from surgical pathology files. Specimens included proliferative phase mucosa (n = 7), secretory phase mucosa (n = 5), nonatypical adenomatous hyperplasia (n = 7), atypical adenomatous hyperplasia (n = 7) and endometrioid adenocarcinoma (n = 30). We calculated the labeling index (LI) for topo II and correlated the findings with the LI for Ki-67. A significant positive correlation was obtained between the Ki-67 and topo II LIs in all of the specimens examined. The levels of the topo II and Ki-67 LIs in secretory phase endometrium were each significantly lower than in the other cases examined. The levels of the topo II and Ki-67 LIs in adenocarcinoma were significantly higher than those in proliferative phase endometrium and nonatypical hyperplasia. There were no significant differences between atypical hyperplasia and adenocarcinoma in the Ki-67 and topo II LIs. The level of the topo II LI in atypical hyperplasia was significantly higher than that in nonatypical hyperplasia, whereas the Ki-67 LI did not differ between atypical and nonatypical hyperplasia. The levels of the Ki-67 LI were significantly higher than those of the topo II LI in proliferative phase endometrium and in nonatypical hyperplasia, but no significant differences were observed between the LIs in atypical hyperplasia and adenocarcinoma. Topo II immunostaining can identify proliferative cells in routinely processed surgical pathology specimens of human endometrium. The relative overexpression of topo II as compared with Ki-67 in adenocarcinoma suggests a dysregulation or qualitative alteration in topo II associated with malignancy, as reported in other tissues. Such over-expression in atypical hyperplasia might reflect the possible premalignant nature of this type of endometrial hyperplasia.

Antigens, Neoplasm↗
PubMed1996

Prevalence of HPV DNA in cervical lesions in patients from Ecuador and Japan.

Cervical cancer is about 6 times more frequent in Ecuador than in Japan. We investigated the association between infection by the human papillomavirus (HPV) and the genesis of cervical cancer in specimens of lesions of the cervical epithelium obtained from patients in Ecuador and Japan. We also examined the results of HPV DNA detection and typing by the polymerase chain reaction (PCR) performed under the same technical conditions in areas with differing rates of cervical cancer. Purified tissue DNA from paraffin-embedded samples was amplified by PCR with universal and type-specific primers. HPV DNA was detected in 8 (20%) of 40 normal cervical epithelial samples from Ecuadorian patients, 19 (45%) of 42 low-grade squamous intraepithelial lesions (LSIL), 16 (50%) of 32 high-grade squamous intraepithelial lesions (HSIL), and 38 (81%) of 47 invasive squamous cell carcinomas (SCC) compared with 3 (10%) of 30 normal cervical specimens from Japanese patients, 107 (51%) of 210 HSILs, and 45 (71%) of 63 SCCs. The prevalence of HPV types 16 and 18 rose significantly with increasing histological grade (p < 0.05). The prevalence of HPV DNA decreased with increasing age in both Ecuadorian and Japanese patients. The detection rate and type-specific distribution of HPV DNA were not correlated with geographic location. Findings suggest that risk factors associated with poverty and underdevelopment may influence the prevalence of HPV infection and the sequence of events after HPV infection culminating in cervical cancer. These factors may help to explain the differing geographic distribution of this disease.

Adult↗
PubMed1995

Prognostic value of epidermal growth factor receptor expression in endometrioid endometrial carcinoma.

We report here a retrospective study of epidermal growth factor receptor (EGFR) expression in 140 patients with human endometrioid endometrial carcinoma (median period of follow-up, 43.8 months; ranging from 1 to 155 months). Tumor specimens were immunohistochemically examined for the overexpression of EGFR, and the correlation among EGFR status, various clinicopathologic parameters, and prognosis was statistically evaluated. Monoclonal antibody (clone 31 G 7), which recognizes the extracellular domain of the EGFR molecule, was used for immunostaining. Ninety-four of 140 cases were immunohistochemically positive for EGFR (67.1%). The presence or absence of EGFR did not correlate with surgical stage, depth of myometrial invasion (DI), or lymph node involvement, but did correlate with histological grade and patient's age. Furthermore, patients with EGFR-positive endometrial carcinoma had a statistically significant shorter length of survival than those with EGFR-negative tumors (P = .018). This trend is more apparent among the patients more than 50 years old (P = .003). When adjusted for surgical stage, DI, and patient age, EGFR status retained prognostic value by multivariate analysis. However, when adjusted for surgical stage, histological grade, DI, and patient age, EGFR status failed to retain prognostic value by multivariate analysis. The results of this study suggest that EGFR expression is correlated with histological grade and greater invasiveness of human endometrioid endometrial carcinoma.

Carcinoma, Endometrioid↗
PubMedDate not supplied

Mass screening for cancer of the endometrium in Miyagi Prefecture, Japan.

OBJECTIVE: To survey the results of mass screening for cancer of the endometrium performed over a six-year period in Miyagi Prefecture, Japan. STUDY DESIGN: Materials were cytodiagnostic samples of the endometrium examined by the Miyagi Cancer Society. The samples were classified into two groups: The mass screening group, from whom samples were collected according to the Health and Medical Service Law for the Aged, and the outpatient group, consisting of samples from other patients. The rates of subjects judged to require close examination and the detection rate of cancer of the endometrium in the two groups were compared. RESULTS: In the mass screening group, the rate of subjects judged to require close examination and the detection rate of cancer of the endometrium were 2.3% and 0.11%, respectively, while they were 5.9% and 0.39%, respectively, in the outpatient group; the differences between the two groups were significant. CONCLUSION: To improve the detection rate in mass screening for endometrial cancer according to the Health and Medical Service Law for the Aged, it is necessary to establish a new criterion for selecting subjects.

Endometrial Neoplasms↗
PubMedDate not supplied

Mass screening for cancer of the uterine cervix in Miyagi Prefecture, Japan. Effects and problems.

OBJECTIVE: To evaluate the effects of and problems with mass screening and in Miyagi Prefecture, Japan. STUDY DESIGN: About 3,570,000 females who underwent mass screening for cervical cancer between 1962 and 1994. RESULTS: The screening rate in the female population aged 30 years or older was 9.5% in 1970, gradually increased and exceeded that rate in 1991 but showed only slight changes thereafter. The standardized death rate due to malignant neoplasm of the cervix fell from 12.1 per 100,000 in 1961 to 4.0 in 1994. CONCLUSION: There still remain various problems, such as lack of a further increase in the screening rate, the fixation of examinees and an increase in the incidence of cervical cancer in young females.

Adult↗
PubMedDate not supplied

Localization of mineralocorticoid receptor and 11 beta-hydroxysteroid dehydrogenase type II in human breast and its disorders.

Mineralocorticoid receptors have been detected in the normal human breast and breast cancers. The expression of mineralocorticoid receptor (MR) and 11 beta-hydroxysteroid dehydrogenase type II (11sHSD2), which confers specificity on MR for aldosterone, was examined by immunohistochemistry in 114 samples from normal human breast and benign and malignant breast lesions in order to study its possible biological significance. MR and 11sHSD2 were immunolocalized in the ductal epithelium in 39/40 (98%) and 36/40 cases (90%) of normal breast, 21/22 (95%) and 15/22 cases (68%) of fibrocystic changes, and 11/11 (100%) and 8/11 (73%) cases of fibroadenoma, respectively. Cases positive for 11 sHSD2 also expressed MR but the patterns of expression varied greatly among examples of normal breast and benign breast diseases. There was a significant correlation between labeling indices of MR and 11sHSD2 in normal breast (p < 0.01) and in benign breast disease (fibrocystic change (p < 0.05) and fibroadenoma (p < 0.05)). In invasive carcinomas, immunoreactivity for MR and 11sHSD2 was detected in malignant cells in 32/41(78%) and 16/41(39%) cases. Both MR and 11sHSD2 labeling indices were significantly higher in invasive ductal carcinoma (22 cases) than invasive lobular carcinoma (19 cases) (p < 0.01). There was a significant correlation between labeling indices of MR and 11sHSD2 when analyzing all infiltrating carcinomas (p < 0.01), but not when assessing invasive lobular or invasive ductal carcinomas separately. These results indicate that the 11 sHSD2 enzyme generally colocalizes with the MR in the ductal epithelial cells of human breast, which may allow aldosterone to occupy its physiological receptor, and the expression of MR and 11sHSD2 appears to be related to ductal differentiation of breast carcinomas.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

Immunolocalization of cyclins D and E and cyclin dependent kinase (cdk) 2 and 4 in human breast carcinoma.

We studied the immunolocalization of cyclins D1 and E and their corresponding partner cyclin dependent kinases (cdk), cdk4 and cdk2 in 41 cases of human breast malignancy (21 invasive ductal carcinomas and 19 invasive lobular carcinomas) and examined the correlation of the labeling indexes among these cyclins, cdks, Ki67, estrogen receptor (ER) and progesterone receptor (PR). Cyclin D1 immunoreactivity was observed exclusively in the nuclei of tumor cells in 27/41 (65%) of the cases examined. Immunoreactivity for cyclin E and cdk2 was detected in all the cases and observed in the nuclei of both carcinoma and non-carcinoma cells. cdk4 immunoreactivity was detected in 39/41 (95%) cases and found in carcinoma and non-carcinoma cells. In all carcinomas examined, a significant correlation was observed only between Ki67 and cyclin D1 (p = 0.0037). However, when examining only invasive ductal carcinomas, a significant correlation was detected between Ki67 and cyclin D1 (p = 0.0069), Ki67 and cdk2 (p = 0.0043) and cyclin D1 and cdk4 (P = 0.0024). Only cyclin D1 correlated with the pathologic stages of the disease and histological grades of invasive ductal carcinoma. Among these cyclins and cdk, overexpression of cyclin D1 is considered to play an important role in the development of human breast malignancy through abnormal proliferation. No significant correlation was observed between steroid receptor status and any of cyclins and cdks examined. Cyclin D1 and cdk2 expression correlated with cell proliferation (Ki67) and cyclin D1 expression with expression of cdk4 in invasive ductal carcinoma but not invasive lobular carcinoma. Cyclin E expression did not correlate with cell proliferation, cyclin D1 or cdks possibly due to deregulation of its expression. These results also indicate different patterns of cyclin D1, cyclin E, cdk2 and cdk4 expression between invasive ductal and lobular carcinoma of human breast.

Breast Neoplasms↗