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K Nanbu

Publications and source records attributed to K Nanbu.

At least 19 recordsLinked to original sources
PubMed2002

Collision group and renormalization of the Boltzmann collision integral.

On the basis of a recently discovered collision group [V. L. Saveliev, in Rarefied Gas Dynamics: 22nd International Symposium, edited by T. J. Bartel and M. Gallis, AIP Conf. Proc. No. 585 (AIP, Melville, NY, 2001), p. 101], the Boltzmann collision integral is exactly rewritten in two parts. The first part describes the scattering of particles with small angles. In this part the infinity due to the infinite cross sections is extracted from the Boltzmann collision integral. Moreover, the Boltzmann collision integral is represented as a divergence of the flow in velocity space. Owing to this, the role of collisions in the kinetic equation can be interpreted in terms of the nonlocal friction force that depends on the distribution function.

Journal Article↗
PubMed2000

Theory of collision algorithms for gases and plasmas based on the boltzmann equation and the landau-fokker-planck equation

A time-explicit formula that describes the time evolution of velocity distribution functions of gases and plasmas is derived from the Boltzmann equation. The formula can be used to construct collision simulation algorithms. Specialization of the formula to the case of the Coulomb interaction shows that the previous method [K. Nanbu, Phys. Rev. E 55, 4642 (1997)] for a Coulomb collision simulation is a solution method of the Landau-Fokker-Planck equation in the limit of a small time step. Also, a collision simulation algorithm for multicomponent plasmas is proposed based on the time-explicit formula derived.

Journal Article↗
PubMed1998

Human chorionic gonadotropin (hCG) inhibits cisplatin-induced apoptosis in ovarian cancer cells: possible role of up-regulation of insulin-like growth factor-1 by hCG.

Gonadotropins have been suggested to play a role in the development or progression of ovarian cancer, and we have previously reported the expression of luteinizing hormone/ human chorionic gonadotropin (LH/hCG) receptor in 40% of epithelial ovarian carcinomas. To examine the biological effect of LH/hCG on ovarian cancer cells, apoptosis induced by cisplatin with or without hCG treatment was investigated in 2 ovarian cancer cell lines, OVCAR-3 and SK-OV-3. Stimulation of cell proliferation by hCG was also studied. In addition, to analyze further the mechanism of hCG signaling involved in apoptosis-inhibition, we examined the expression of LH/hCG receptors and the regulation by hCG for apoptosis-inhibitory pathways, such as the bcl-2/bax system and the insulin-like growth factor-1 (IGF-1)/IGF-1 receptor (IGFR) system. hCG did not increase cell proliferation in either cell line. However, hCG treatment suppressed cisplatin-induced apoptosis by 58% in the OVCAR-3 cells, as shown by immunofluorescent staining and quantitation of DNA fragmentation. LH/hCG receptor mRNA was expressed only in OVCAR-3, and no apoptosis-inhibitory effect of hCG was observed in the SK-OV-3 cells that did not express the receptor. In the OVCAR-3 cells, hCG significantly increased mRNA expression of IGF-1, but did not change mRNA levels of bcl-2/bax. Our findings suggest that LH/hCG influences the chemosensitivity of ovarian cancer cells through an apoptosis-inhibitory signal possibly via up-regulation of IGF-1 expression.

Apoptosis↗
PubMed1998

Tumor response to neoadjuvant chemotherapy correlates with the expression of P-glycoprotein and PCNA but not GST-pi in the tumor cells of cervical carcinoma.

OBJECTIVE: To identify the clinicopathological and chemoresistant factors predicting the response to neoadjuvant chemotherapy and the patient prognosis in high-risk cervical carcinomas. METHODS: We retrospectively reviewed 47 patients with locally advanced or bulky cervical carcinoma treated with two courses of intraarterial infusion of cisplatin, doxorubicin, mitomycin C, and 5-fluorouracil (5-FU), followed by radical hysterectomy at our hospital between 1988 and 1995. Expressions of the chemoresistance-related proteins, such as P-glycoprotein, glutathione S-transferase pi (GST-pi), and proliferating cell nuclear antigen (PCNA) in the tumor cells, were examined by immunohistochemistry using pretreatment biopsy specimens. These results were compared with the chemotherapeutic response, which was evaluated by magnetic resonance imaging (MRI) and histopathology. Outcome of the patients was also studied. RESULTS: Chemotherapeutic effect of either complete (CR) or partial (PR) response on MRI was obtained in 36 of the 47 (86%) patients. Poor response to chemotherapy was significantly correlated with P-glycoprotein expression (P < 0.005) and low PCNA labeling (P < 0. 05), but not GST-pi expression in the tumor cells. Independent prognostic factors for patient survival were parametrial involvement and lymph node metastasis. Neither the expression of GST-pi nor PCNA was correlated with the patient survival. CONCLUSION: Assessment of the expression of P-glycoprotein and PCNA is potentially useful for the prediction of tumor response to neoadjuvant chemotherapy for cervical carcinomas.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Heterogeneous distribution of K-ras-mutated epithelia in mucinous ovarian tumors with special reference to histopathology.

The carcinogenic process of epithelial ovarian carcinomas is still unknown, and both pathways of de novo carcinogenesis from the surface epithelium and malignant transformation of benign cystadenoma have been suggested. Especially in mucinous ovarian tumors, the transition from benign cystadenomas to tumors of low malignant potential (LMP) or carcinomas has been implicated. To elucidate this possibility, we analyzed the presence or absence of heterogeneity of the K-ras mutation corresponding to the histological heterogeneity in 71 epithelial ovarian tumors, including 31 mucinous tumors. K-ras mutation was identified in nine mucinous tumors (4 of 10 carcinomas, 4 of 14 LMP tumors, and 1 of 7 cystadenomas) and in two nonmucinous carcinomas. Microdissection of multiple sites with reference to their histological appearance showed the heterogeneous distribution of K-ras-mutated epithelia in two of the nine mucinous tumors. One mucinous carcinoma showed K-ras mutation in all of the histologically LMP and malignant portions, but not in benign portions. In another LMP tumor, all of the LMP portions and one of the benign portions showed K-ras mutation, whereas the other two benign portions had no mutation. In the remaining seven mucinous tumors with K-ras mutation, however, there was a homogeneous distribution of K-ras-mutated epithelia irrespective of their histological appearance. These findings suggest that the K-ras mutation occurs during the transformation from benign cystadenomas to LMP or malignant lesions, providing molecular genetic support for the hypothesis of the "adenoma-carcinoma sequence" in some mucinous ovarian tumors, but in other cases an alternative pathway may also be possible.

Adenocarcinoma, Mucinous↗
PubMed1998

Expression of abnormal transcripts of the FHIT (fragile histidine triad) gene in ovarian carcinoma.

To elucidate the role of the FHIT (fragile histidine triad) gene in ovarian carcinogenesis, the expression of the gene was analysed by reverse transcription-polymerase chain reaction (RT-PCR) in 51 cases of ovarian carcinoma, 6 cases of borderline tumour and 4 cases of benign ovarian tumour. The concomitant expressions of normal and abnormal FHIT transcripts were detected in 39% of carcinomas and in 83% of borderline tumours, while benign tumours and normal ovarian tissues expressed only normal transcript. In addition, there were 4 (8%) cases of carcinoma lacking expression of normal FHIT transcript, all of which were in advanced stages (stage III-IV) and poorly differentiated. These results suggest that the expression of abnormal transcripts of the FHIT gene is a feature of ovarian malignant/borderline tumours and that the complete loss of normal FHIT expression is related to the progression of ovarian carcinoma in a subset of the cases. However, abnormal FHIT transcripts themselves were not associated with any clinicopathological parameters, such as clinical stage, histological subtype of tumour, grade of differentiation or outcome of the patient. Additionally, abnormal FHIT expression was not associated with the presence of loss of heterozygosity (LOH) at this locus, suggesting that abnormal FHIT transcripts are not derived from genetic alteration or that genetic alteration at this locus is complicated.

Acid Anhydride Hydrolases↗
PubMed1998

Prognostic significance of heat shock proteins HSP70 and HSP90 in endometrial carcinomas.

Heat shock proteins HSP70 and HSP90 are sex steroid receptor-associated proteins, and HSP90 expression has reportedly been correlated with sex steroid receptor status in endometrial carcinomas. HSP70 is also known to associate with several oncogene products such as p53 protein, and expression of HSP70 has been reported to be a prognostic factor in several malignant neoplasms. In endometrial carcinomas, however, little is known about the prognostic significance of these proteins. Therefore, we analyzed the survival of 44 endometrial carcinoma patients treated in our hospital with reference to the immunohistochemical expressions of HSP70 and HSP90, as well as the clinicopathological factors such as age, menstrual status, FIGO stage, histologic grade, p53 protein overexpression, and sex steroid receptor status. The expression of HSP70 was observed in 50% (22 cases), and strong HSP90 expression in 30% (13 cases) of the 44 carcinomas. The patients with HSP70-positive tumors showed significantly poorer survival than the patients with HSP70-negative tumors (p = 0.045), although multivariate analysis did not reveal HSP70 expression to be an independent prognostic factor. In contrast, the strong expression of HSP90 in the tumor was significantly correlated with a favorable prognosis of the patient (p = 0.026). Other prognostic indicators were FIGO stage (p = 0.0086) and the expression of progesterone receptor (p = 0.042). Accordingly, expressions of HSP70 and HSP90 each have different prognostic significance in endometrial carcinoma and may be useful for prediction of patient survival.

Adult↗
PubMed1998

Early invasive adenocarcinoma of the fallopian tube: a case report and review of the literature.

We present an early invasive adenocarcinoma of the fallopian tube, which was incidentally found in a 45-year-old woman undergoing a laparotomy for uterine myoma. Histological examination of the hydropic tubes revealed widespread endosalpingeal hyperplasia without atypia in both tubes. In addition, the left tube contained 3 scattered lesions of carcinoma in situ, one of which was accompanied by a microfocus of definite stromal invasion confined within the endosalpingeal mucosa. Such a case seems extremely rare, and it might represent the histological appearance of an early invasive feature of tubal carcinoma. We reviewed previously reported cases of in situ and/or early invasive carcinomas of the fallopian tube with respect to the pathological diagnosis and histogenesis of primary tubal adenocarcinomas.

Adenocarcinoma↗
PubMed1997

Increased expression of LH/hCG receptors in endometrial hyperplasia and carcinoma in anovulatory women.

Endometrial hyperplasias and carcinomas are well documented to occur in anovulatory women with or without polycystic ovarian syndrome (PCO), which is characterized by hypersecretion of luteinizing hormone (LH). Although overexpression of LH/human chorionic gonadotropin (hCG) receptors has been demonstrated in endometrial carcinomas, whether LH/hCG receptors are also expressed in the endometrial hyperplasias is not known. In this study, the expression of LH/hCG receptors as well as that of progesterone receptors (PR) was analyzed by immunohistochemistry in 20 cases of normal endometria and 24 cases of endometrial hyperplasia and carcinoma (9 simple hyperplasias, 6 complex hyperplasias, 6 atypical hyperplasias, and 3 well-differentiated carcinomas). Fifteen of the 24 patients were 40 years old or younger, presumably anovulatory by BBT chart. Serum levels of LH, follicular stimulating hormone (FSH), prolactin, estradiol, and testosterone were measured by radioimmunoassay. Expression of LH/hCG receptors was detected in 19 of the 21 hyperplasias with a relatively stronger staining intensity in the glandular cells of complex or atypical hyperplasia as compared with normal endometrial glands or simple hyperplasia. In addition, all of the 3 carcinoma specimens showed stronger expression of LH/hCG receptors compared with normal endometria. The expression of LH/hCG receptors was well correlated with the staining for PR. Hormonal assay revealed 3 women to have the typical endocrinological profile of PCO. These findings suggest that the increased expression of LH/hCG receptors is a feature of endometrial hyperplasia and carcinoma developing in younger anovulatory women including those with PCO.

Adult↗
PubMed1997

Time-course ultrasonographic observation of a mesenteric pseudocyst of the sigmoid colon: report of a case.

A 35-year-old woman was referred to our hospital for investigation of lower abdominal pain and a feeling of fullness. At her first consultation, a transvaginal ultrasonography (US) revealed a homogeneous cystic mass in the lower abdomen. Over a period of 8 months the US findings of the content of this mass changed from fine and faint internal echoes to moderate amounts of irregularly contoured internal echoes. At laparotomy, the cystic mass, which measured 3.0 x 3.0 x 3.5 cm, appeared to arise in the sigmoid mesocolon and tightly adhered to the appendix. The cyst was unilocular and contained a slightly yellow gelatinous fluid. Microscopically, its wall was fibrous and lacked an epithelial lining, suggesting that it was a so-called pseudocyst arising from the sigmoid mesocolon. To our knowledge, this is the first case report documenting the time-course ultrasonographic observations of a mesenteric pseudocyst. Our findings suggest that the time-elapsed ultrasonographic changes might have been dependent on the interval between the onset of cystic formation and the US examination.

Adult↗
PubMed1997

Messenger ribonucleic acid expression of LH/hCG receptor gene in human ovarian carcinomas.

The mRNA expression of luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors was analysed by the RT-nested PCR method in five normal ovarian tissues, 62 ovarian tumours (5 benign, 7 borderline and 43 malignant epithelial tumours, 3 sex cord-stromal tumours and 4 germ cell tumours) and in 2 ovarian cancer cell lines. In normal ovaries, two cDNA fragments of different sizes were detected using primers designed to amplify a region including exon 9. Sequencing revealed that the larger fragment was derived from a full-length receptor, while the smaller fragment was a splice variant lacking exon 9. In ovarian tumours, the larger fragment of LH/hCG receptors was detected in 40% of the epithelial ovarian carcinomas, none of the germ cell tumours, all of the sex cord-stromal tumours and one of the 2 ovarian cancer cell lines. Immunohistochemistry confirmed the localisation of LH/hCG receptor protein in the tumour cells which correlated with mRNA expression. Patients with full-length LH/hCG receptors in carcinomas showed a better prognosis compared with those without the receptors.

Biomarkers, Tumor↗
PubMed1997

Expression of vascular endothelial growth factor (VEGF) in epithelial ovarian neoplasms: correlation with clinicopathology and patient survival, and analysis of serum VEGF levels.

Vascular endothelial growth factor (VEGF) is known to be produced by various solid tumours and is thought to be involved in microvascular permeability and/or angiogenesis. To examine the relationship between VEGF expression in ovarian neoplasms and clinicopathological factors or patient survival, expression of VEGF was analysed immunohistochemically in 110 epithelial ovarian tumours. In addition, VEGF levels in the tumour fluid (17 patients), ascites (12 patients) and sera (38 patients) were determined using enzyme immunoassay. Positive immunostaining for VEGF was observed in 97% (68 out of 70) of ovarian carcinomas, which was significantly higher than that of tumours of low malignant potential (LMP) (13 out of 25; 52%) and benign cystadenomas (5 out of 15; 33%) (P < 0.01). In ovarian carcinomas, strong VEGF immunostaining was also observed more frequently in tumours of clear cell type (P < 0.05) in the advanced stage of disease (P < 0.05) and with positive peritoneal cytology (P < 0.01). Patients with strong VEGF staining had poorer survival rates than those with weak or no immunostaining for VEGF (P < 0.01). These findings suggest that strong VEGF expression plays an important role in the tumour progression of ovarian carcinoma. The enzyme immunoassay revealed higher serum VEGF levels in carcinoma patients than those in patients with LMP or benign tumours (P < 0.01). Serum VEGF levels decreased after the successful removal of tumours in ovarian cancer patients and, in one patient, the serum VEGF level was re-elevated during relapse. Therefore, serum VEGF could be used as a marker for monitoring the clinical course of ovarian cancer patients.

Adult↗
PubMed1997

Extraovarian sex cord-stromal tumor: case report and review of the literature.

A 45-year-old woman was found at laparotomy to have a multinodular solid tumor within the broad ligament, which was removed by total hysterectomy and bilateral salpingo-oophorectomy. Both ovaries were unremarkable. Three years after the operation, retroperitoneal tumor was detected, which was associated with clinical evidence of estrogen production. Histological examination of the primary and retroperitoneal tumors showed histological features that resembled those of granulosa cell tumors. Previously reported sex cord-stromal tumors arising in extraovarian sites were reviewed with respect to the histogenesis of these tumors.

Cell Nucleus↗
PubMed1997

Diffuse cystic change of a term placenta with a normal newborn.

We recently encountered a case of term placenta with a diffuse cystic lesion of the villi. A 19-year-old primipara at 36 weeks of gestation underwent cesarean section due to breech presentation with premature rupture of the membranes; she delivered a mature male baby of 2,502 g with an Apgar score of 9/9. The placenta was 940 g in weight and 29 x 20 x 3 cm in size, and macroscopically had multiple cystic lesions (3-8 mm in diameter) that resembled hydatidiform moles. However, histopathological examination revealed that the severe hydropic change was localized in the stem villi but not remarkable in the terminal chorionic villi. Moreover, abnormal proliferation of the trophoblast was not observed. However, the hypertrophic change was observed in the vascular wall of stem villi, in which hyperplasia of smooth muscle-like cells was present. The urinary hCG levels at 1 month and 2 months after delivery were less than 50 IU/l. These findings indicate that the multiple cystic lesions of the placenta in this case are essentially different from those of a trophoblastic disease, and that the diffuse cystic lesion of the villi might have been secondary to changes in the local circulation.

Actins↗
PubMed1997

Messenger ribonucleic acid expression of heat shock proteins HSP70 and HSP90 in human endometrium and myometrium during the menstrual cycle.

Heat shock proteins of 72 and 90 kDa (HSP70, HSP90) are thought to be involved in the functional modulation of sex steroid receptors. To examine the expression and transcriptional regulation of HSP70 and HSP90 in both the endometrium and myometrium, messenger ribonucleic acid (mRNA) and protein level expression of these HSPs during various phases of the menstrual cycle were analyzed by Northern blotting and immunohistochemistry. In the endometrium, HSP70 mRNA levels increased during the secretory phase compared with levels during the proliferative phase; this is consistent with the stronger immunostaining of HSP70 in glandular cells in the secretory phase. In the myometrium, however, mRNA and protein expression of HSP70 were higher in the proliferative phase than in the secretory phase. This indicates that the regulatory mechanism of HSP70 expression during the menstrual cycle differs between the endometrial glandular cells and myometrial smooth muscle cells and may be correlated with the period of sex steroid-related functions of the respective cells. Expression of the HSP90 mRNA and protein in the myometrium was higher in the proliferative phase than in the secretory phase. In the endometrium, HSP90 immunostaining in the glandular cells was also stronger in the proliferative phase, although expression of HSP90 mRNA was not significantly different between the tissues of the two phases.

Adult↗
PubMed1997

Immunohistochemical localization of basic fibroblast growth factor (bFGF) during folliculogenesis in the human ovary.

Basic fibroblast growth factor (bFGF) has been suggested to be one of the intraovarian regulators of ovarian folliculogenesis, but its localization in the human ovary remains to be determined. We examined the immunohistochemical reactivity for bFGF in the course of follicular development and corpora lutea formation in the human ovary. Pregranulosa cells in the primordial follicle were negative, but at the preantral stage both granulosa and theca cells showed weakly positive immunostaining for bFGF. In the antral follicles, both granulosa and theca interna cells showed stronger staining for bFGF with the increase in follicular diameter. In atretic follicles at various stages, granulosa cells were negative or weakly positive for bFGF, whereas luteinized theca cells showed strong immunoreactivity. In the corpora lutea during the early luteal phase, granulosa lutein cells were strongly positive for bFGF but in the late luteal phase became immunonegative. On the other hand, bFGF staining in theca lutein cells was strong throughout the course of corpora lutea formation and regression. These findings suggest that bFGF is localized not only in granulosa cells but also in theca cells, and in the latter, bFGF immunoreactivity is associated with luteinization.

Adult↗
PubMed1997

Expression of vascular endothelial growth factor (VEGF) during folliculogenesis and corpus luteum formation in the human ovary.

Vascular endothelial growth factor (VEGF) has been suggested to be involved in angiogenesis and microvascular hyperpermeability. We examined immunohistochemically the expression of VEGF in the granulosa and theca cells, along with that of proliferating cell nuclear antigen (PCNA), in the vascular endothelium during the course of follicular development and corpora lutea formation in human ovaries. The immunolocalization of VEGF in these cells was compared with that of another putative angiogenic factor, basic fibroblast growth factor (bFGF). The granulosa cells in the primordial and primary follicles were VEGF negative, but at the preantral stage, the granulosa cells showed weakly positive immunostaining for VEGF. However, the VEGF immunostaining in the granulosa cells was weak throughout the folliculogenesis. In contrast, the theca interna cells of developing follicles showed strong staining for VEGF, which was well correlated with the PCNA positivity in the vascular endothelial cells in the thecal layer. In the atretic follicles, the granulosa and theca cells were VEGF negative. In the corpora lutea, VEGF was strongly expressed in both granulosa and theca lutein cells in the early luteal phase when the PCNA positivity in the endothelium increased, but the VEGF staining in these cells became weak in the mid- and late luteal phases. Accordingly, the PCNA positivity in the vascular endothelium was well correlated with the expression of VEGF in the theca cells during follicular development and atresia, and that in the granulosa and theca lutein cells in corpora lutea formation and regression. In addition, the immunolocalization of VEGF was different from that of bFGF.

Biopsy↗