Biomedical subjects

K Okamura

Publications and source records attributed to K Okamura.

At least 19 recordsLinked to original sources

PubMed2006

Effective dose of A-bomb radiation in Hiroshima and Nagasaki as assessed by chromosomal effectiveness of spectrum energy photons and neutrons.

The effective dose of combined spectrum energy neutrons and high energy spectrum gamma-rays in A-bomb survivors in Hiroshima and Nagasaki has long been a matter of discussion. The reason is largely due to the paucity of biological data for high energy photons, particularly for those with an energy of tens of MeV. To circumvent this problem, a mathematical formalism was developed for the photon energy dependency of chromosomal effectiveness by reviewing a large number of data sets published in the literature on dicentric chromosome formation in human lymphocytes. The chromosomal effectiveness was expressed by a simple multiparametric function of photon energy, which made it possible to estimate the effective dose of spectrum energy photons and differential evaluation in the field of mixed neutron and gamma-ray exposure with an internal reference radiation. The effective dose of reactor-produced spectrum energy neutrons was insensitive to the fine structure of the energy distribution and was accessible by a generalized formula applicable to the A-bomb neutrons. Energy spectra of all sources of A-bomb gamma-rays at different tissue depths were simulated by a Monte Carlo calculation applied on an ICRU sphere. Using kerma-weighted chromosomal effectiveness of A-bomb spectrum energy photons, the effective dose of A-bomb neutrons was determined, where the relative biological effectiveness (RBE) of neutrons was expressed by a dose-dependent variable RBE, RBE(gamma, D (n)), against A-bomb gamma-rays as an internal reference radiation. When the newly estimated variable RBE(gamma, D (n)) was applied to the chromosome data of A-bomb survivors in Hiroshima and Nagasaki, the city difference was completely eliminated. The revised effective dose was about 35% larger in Hiroshima, 19% larger in Nagasaki and 26% larger for the combined cohort compared with that based on a constant RBE of 10. Since the differences are significantly large, the proposed effective dose might have an impact on the magnitude of the risk estimates deduced from the A-bomb survivor cohort.

Adult↗

PubMed2006

Clinical outcome and risk factors for recurrence in borderline ovarian tumours.

We investigated the long-term prognosis of borderline ovarian tumours and determined risk factors for recurrence. One hundred and twenty-one borderline ovarian tumours treated between 1994 and 2003 at the participating institutions in the Tohoku Gynecologic Cancer Unit were retrospectively investigated for clinical stage, histopathological subtype, surgical technique, postoperative chemotherapy, the presence or absence of recurrence, and prognosis. The median follow-up period was 57 months (1-126 months). One hundred and nine cases (90.6%) were at clinical stage I. The histopathological subtypes consisted of 91 cases of mucinous tumour (75.2%), 27 cases of serous tumour (22.3%), and three cases of endometrioid tumour. Conservative surgery was used in 53 cases (43.8%), radical surgery in 68 cases (56.2%), a staging laparotomy in 43 cases (35.5%), and postoperative adjuvant therapy in 30 cases (24.8%). Recurrence was found in eight cases, but no tumour-related deaths were reported. Although no significant difference in disease-free survival rate was seen between different clinical stages, the difference in disease-free survival rate between serous and non-serous (mucinous and endometrioid) types was significant (P<0.05). The 10-year disease-free survival rate was 89.1% for the radical surgery group and 57.4% for the conservative surgery group -- this difference was significant (P<0.05). In the conservative surgery group, cystectomy and serous tumour were independent risk factors for recurrence. Although recurrence was observed, the long-term prognosis of borderline ovarian tumour was favourable, without tumour-related deaths. Considering the favourable prognosis, conservative surgery can be chosen as far as the patient has a non-serous tumour and receive adnexectomy. However, in cases of serous type and/or receiving cystectomy special care should be given as relative risk rates of recurrence elevate by 2-4-folds.

Adult↗

PubMed2006

Cervicothoracic malignant peripheral nerve sheath tumor in a 12-year-old girl with neurofibromatosis type 1.

We encountered a 12-year-old girl with neurofibromatosis type 1 (NF1) who developed a low-grade cervicothoracic malignant peripheral nerve sheath tumor (MPNST). Computed tomography of the neck showed an elastic firm tumor measuring 7 x 6 x 4 cm and arising from the upper mediastinum. She had no pain or neurological symptoms, but the tumor enlarged to ca. 8 x 8 x 4 cm over the following 7 months. Although we had diagnosed a neurofibroma by preoperative incisional biopsy, the resected tumor showed low-grade MPNST in the central portion of the tumor. In treating a tumor in a patient with NF1, we must recognize that partial biopsies do not necessarily establish a definitive diagnosis and that a growing tumor may indicate malignant transformation.

Child↗

PubMed2006

Lessons from comparative analysis of species-specific imprinted genes.

Genomic imprinting is generally believed to be conserved in all mammals except for egg-laying monotremes, suggesting that it is closely related to placental and fetal growth. As expected, the imprinting status of most imprinted genes is conserved between mouse and human, and some are imprinted even in marsupials. On the other hand, a small number of genes were reported to exhibit species-specific imprinting that is not necessarily accounted for by either the placenta or conflict hypotheses. Since mouse and human represent a single, phylogenetically restricted clade in the mammalian class, a much broader comparison including mammals diverged earlier than rodents is necessary to fully understand the species-specificity and variation in evolution of genomic imprinting. Indeed, comparative analysis of a species-specific imprinted gene Impact using a broader range of mammals led us to propose an alternative dosage control hypothesis for the evolution of genomic imprinting.

Animals↗

PubMed2006

Roles of CLCA and CFTR in electrolyte re-absorption from rat saliva.

A molecular basis for Cl- re-absorption has not been well-characterized in salivary ductal cells. Previously, we found strong expression of a rat homologue proposed to be Ca2+-dependent Cl- channels (rCLCA) in the intralobular ducts of the rat submandibular gland. To address the question as to whether rCLCA and cystic fibrosis transmembrane conductance regulator (CFTR) are involved in Cl- re-absorption, we evaluated the electrolyte content of saliva from glands pre-treated with a small interfering RNA (siRNA). Retrograde injection into a given submandibular duct of an siRNA designed to knock down either rCLCA or CFTR reduced the expression of each of the proteins. rCLCA and CFTR siRNAs significantly increased Cl- concentration in the final saliva during pilocarpine stimulation. These results represent the first in vivo evidence for a physiological significance of rCLCA, along with CFTR, in transepithelial Cl- transport in the ductal system of the rat submandibular gland.

Absorption↗

PubMed2006

CT analysis of the Stafne's bone defects of the mandible.

OBJECTIVE: To investigate the aetiology of Stafne's bone defects by analysing the CT findings of two types of defects, which appeared differently on panoramic radiographs. METHODS: 32 lesions with suspicion of the Stafne's bone defect on a panoramic radiograph were categorised into two groups: typical "Stafne type", which showed the connection to the base of the mandible, and non-typical "Cyst type", which showed no connection. Age, sex, the existence of hypertension and the following CT findings: location, size and inner content of the defect, existence of expansion of the buccal cortical bone, and location of submandibular glands, were analysed. RESULTS: There were 14 "Stafne type" and 17 "Cyst type" on the panoramic radiographs. One lesion in the "Cyst type" was a true cystic lesion and was excluded from further review. The "Stafne type" was seen primarily in the posterior and inferior locations, while the "Cyst type" was seen in the anterior and superior locations on the CT. The size of the defect was significantly larger in the "Stafne type". Buccal cortical expansion was observed only in three lesions in the "Stafne type". While the "Cyst type" contained mainly fatty tissue, the "Stafne type" contained other soft tissues. Though the submandibular glands on the defect side were located anteriorly in both types compared with those on the contralateral side and on the control patients, they spread mainly outwards in the "Stafne type". CONCLUSION: The Stafne's bone defects are thought to be caused by the dislocated submandibular gland. The differences between the two types might occur as a result of a different location of the submandibular gland.

Adipose Tissue↗

PubMed2005

International transmission of uncompressed endoscopic surgery images via superfast broadband Internet connections.

BACKGROUND: Although telecommunication is increasing in popularity, poor-quality images sent through a narrowband network limit its use in the medical field. METHODS: Kyushu University Hospital in Japan and four hospitals in Korea were linked via superfast broadband Internet connection. The digital video transfer system, which can transmit digital videos without loss of image quality, was used, and the bandwidth was 30 Mbps per line. RESULTS: Of the 16 teleconferences conducted, 6 demonstrated real-time endoscopic surgery. In addition to the surgical images, preoperative diagnostic images, images of the operating room, and images of the staff in the conference room were transmitted to facilitate discussion. The network remained stable, and the sound delay was restricted to less than 0.3 s. In the other 10 teleconferences, recorded video images were used for discussion. CONCLUSIONS: The authors have established a high-quality, practical teleconference system that is economical and easy to use in clinical practice. This system shows promise for remote education beyond geographic borders.

Cholecystectomy, Laparoscopic↗

PubMed2005

IL-1beta treatment does not co-ordinately up-regulate mPGES-1 and COX-2 mRNA expression, but results in higher degree of cellular and intracellular co-localization of their immunoreactive proteins in human placenta trophoblast cells.

PGE2 is involved in initiation and progression of labor in many species. Biosynthesis of PGE2 is mediated by cyclooxygenases (COX) and prostaglandin E synthases (PGES). mPGES-1 and COX-2 form an inducible pathway for PGE2 production in many cell systems. In this study we investigated whether mPGES-1 is involved in cytokine induced PGE2 biosynthesis in human trophoblast cells. We have evaluated the cellular and intracellular co-localization of mPGES-1 and COX-2, as well as cPGES and COX-1 in human trophoblast cells by dual immunofluorescent staining. The effect of IL-1beta on mPGES-1 and COX-2 co-localization, such as would occur with infection, and the regulatory effects of pro-inflammatory cytokines IL-1beta and TNF-alpha on transcriptional activity of mPGES-1 and COX-2 in these cells were also studied. We found that in cultured unstimulated trophoblasts, some cells expressed predominantly either mPGES-1 or COX-2, though there were cells co-expressing both enzymes. With IL-1beta treatment, mPGES-1 and COX-2 became more consistently co-localized. mPGES-1 was not transcriptionally co-induced with COX-2 by the cytokine treatment. We conclude that mPGES-1 is not involved in the inducible COX-2 mediated pathway for PGE2 biosynthesis at the transcriptional level, however, the treatment with IL-1beta results in a higher degree of co-ordination of the mPGES-1 and COX-2 protein immunolocalization, eliciting PGE2 synthesis.

Adult↗

PubMed2005

The macrophage stimulating protein/RON system: a potential novel target for prevention and treatment of endometriosis.

Our recent DNA microarray analysis using tissue obtained by laser capture microdissection (LCM) identified up-regulation of RON (a tyrosine kinase receptor) during the late secretory phase in eutopic endometrial epithelial cells from patients with deep endometriosis compared with control endometrium from women with macroscopically normal pelvic cavities. In the present study, we further investigated mRNA expression of RON and its ligand, macrophage stimulating protein (MSP), in deep endometriotic lesions, eutopic endometrium from patients with deep endometriosis and control endometrium by using LCM and quantitative real-time RT-PCR. MSP mRNA expression in endometrial epithelial cells was significantly up-regulated in endometriosis patients during the late secretory phase compared with expression in controls. Furthermore, we detected up-regulation of MSP mRNA in ectopic endometrial epithelial cells compared with matched eutopic endometrial epithelial cells within the same patients regardless of the menstrual phase. MSP has an intrinsically dual functional nature through its receptor RON-it is a trophic cytokine preventing apoptosis and a scatter factor promoting invasion, both of which may be necessary for the initial development and growth of endometriosis. The present findings suggest that the MSP/RON system may be involved in the pathophysiology of endometriosis.

Adult↗

PubMed2005

Keratan sulphate levels in mucopolysaccharidoses and mucolipidoses.

The mucopolysaccharidoses (MPS) is characterized by accumulation of glycosaminoglycans (GAGs), and mucolipidosis (ML) by accumulation of GAGs and sphingolipids. Each type of MPS accumulates specific GAGs. The lysosomal enzymes N-acetylgalactosamine-6-sulphate sulphatase and beta-galactosidase involve the stepwise degradation of keratan sulphate (KS). Deficiency of these enzymes results in elevation of KS levels in the body fluids and in tissues, leading to MPS IV disease. In this study, we evaluated blood and urine KS levels in types of MPS and ML other than MPS IV. Eighty-five plasma samples came from MPS I (n = 18), MPS II (n = 28), MPS III (n = 20), MPS VI (n = 3), MPS VII (n = 5) and ML (n = 11) patients while 127 urine samples came from MPS I (n = 34), MPS II (n = 34), MPS III (n = 32), MPS VI (n = 7), MPS VII (n = 9) and ML (n = 11) patients. KS levels were determined using the ELISA method. Plasma KS levels varied with age in both control and patient populations. In all age groups, the mean values of plasma KS in MPS and ML patients were significantly higher than those in the age-matched controls. Plasma KS values in four newborn patients were above the mean + 2SD of the age-matched controls (mean, 41 ng/ml). Overall, 85.9% of individual values in non-type IV MPS and ML patients were above the mean + 2SD of the age-matched controls. For urine KS levels, 24.4% of individual values in patients were above the mean + 2SD of the age-matched controls. In conclusion, KS in blood is elevated in each type of non-type IV MPS examined, in contrast to the conventional understanding. This finding suggests that measurement of KS level provides a new diagnostic biomarker in a wide variety of mucopolysaccharidoses and mucolipidoses in addition to MPS IV.

Adolescent↗

PubMed2005

Correlation between diagnostic accuracy and perceptibility.

OBJECTIVES: To correlate diagnostic accuracy for proximal caries with perceptibility of low contrast image details using regression analysis. The other purpose was to determine the attenuation range required for proximal caries diagnosis. METHODS: The results of the two types of observer performance tests described above were retrieved from previous studies. Recording media included in those studies were the Compuray and the Dixel, direct digital radiographic systems, and Ektaspeed Plus film. The average numbers of perceptibility of image details from five observers were calculated for each step and for every combination of contiguous steps of the aluminium test phantom from the perceptibility test. The average diagnostic accuracy for proximal caries from the same five observers was correlated with the total number of perceptible details from the phantom using regression analysis. Finally, attenuation range required for proximal caries diagnosis was calculated from the attenuation range of the phantom where the maximum correlation coefficient was obtained. RESULTS: Maximum correlation (r=0.68) was obtained at the combination of five contiguous steps of the aluminium test phantom. Attenuation range required for proximal caries diagnosis corresponded to the 2 mm to 6 mm thickness of aluminium with acrylic block of 12 mm thickness. CONCLUSIONS: There is a correlation between perceptibility of low contrast image details and diagnostic accuracy for proximal caries. There may be a possibility to simplify observer performance tests for proximal caries diagnosis by using the standardized phantom simulating its attenuation range.

Adolescent↗

PubMed2005

Effects of the automatic exposure compensation on the proximal caries diagnosis.

OBJECTIVE: To elucidate the effect of automatic exposure compensation (AEC) on the diagnostic accuracy of proximal caries by comparing several digital intraoral imaging systems with a film. MATERIALS AND METHODS: Twenty-seven extracted teeth served as proximal caries samples. Three digital radiographic systems; the Compuray, the Dixel, and the Sens-A-Ray without scintillator layer, and Kodak Ekta-speed Plus films were used as recording media. Radiographs of the teeth samples were obtained with each recording medium under seven to eight different exposures including the optimum level. Six oral radiologists evaluated the possibility of proximal caries with the five-grade-confidence-scale. On digital radiographs, image manipulations were allowed after the initial assessment. Receiver operating characteristic (ROC) curves were obtained at each exposure in each recording medium. The area under the ROC curve (Az) was used as the representative value of diagnostic accuracy. Diagnostic accuracy (DA) curves were obtained by plotting averaged Az values from all observers as a function of incident exposure in each system. RESULTS: The effect of exposure variation on the DA was slight in the film while it was significantly larger in the digital systems without AEC. Among digital systems, the effect of exposure variation was smaller in the system with AEC than those without AEC. There was no significant effect on the diagnostic accuracy even if digital image manipulation was employed. CONCLUSION: AEC minimizes the decrease of DA due to inadequate exposures. Since it compensates for the narrow exposure range in the digital intraoral sensor systems, the system with AEC may be preferable for the clinical diagnostic tasks.

Adolescent↗

PubMed2005

Differentiation effects by the combination of spheroid formation and sodium butyrate treatment in human hepatoblastoma cell line (Hep G2): a possible cell source for hybrid artificial liver.

The aim of this study was to investigate the feasibility of human hepatoblastoma cell line (Hep G2), which differentiates by spheroid formation, and treatment with sodium butyrate (SB) as a cell source for hybrid artificial liver (HAL). Hep G2 spontaneously formed spheroids in polyurethane foam (PUF) within 3 days of culture and restored weak ammonia removal activity. Treatment with SB, which is a histone deacetylase inhibitor, further increased the ammonia removal activity of Hep G2 spheroids in a concentration-dependent manner. The activation of ornithine transcarbamylase--a urea cycle enzyme--was significantly related to the upregulation of ammonia removal by spheroid formation, but scarcely contributed to the further upregulation following SB treatment. In contrast with ammonia removal, treatment with SB reduced the albumin secretion of Hep G2 spheroids in a concentration-dependent manner. In the PUF-HAL module in a circulation culture, the ammonia removal rate and albumin secretion rate (per unit volume of the module) of Hep G2 spheroids treated with 5 mM SB were almost the same as those of primary porcine hepatocyte spheroids. These results suggest that simultaneous use of spheroid formation and SB treatment in Hep G2 is beneficial in enhancing the functions of human hepatocytes with potential applications in regenerative medicine and drug screening.

Albumins↗

PubMed2004

DNA microarray analysis of gene expression profiles in deep endometriosis using laser capture microdissection.

Endometriosis, a common gynecological disorder that causes infertility and pelvic pain, is defined as the presence of endometrial glands and stroma within extra-uterine sites. However, despite extensive studies its etiology and pathogenesis are not completely understood. Differentially expressed genes were investigated in epithelial and stromal cells from deep endometriosis and matched eutopic endometrium using cDNA microarrays and laser capture microdissection. Validation of results of several up- and down-regulated genes was performed by quantitative real-time RT-PCR. Our data showed that platelet-derived growth factor receptor alpha (PDGFRA), protein kinase C beta1 (PKC beta1) and janus kinase 1 (JAK1) were upregulated, and Sprouty2 and mitogen-activated protein kinase kinase 7 (MKK7) were downregulated in endometriosis stromal cells, suggesting the involvement of the RAS/RAF/MAPK signaling pathway through PDGFRA in endometriosis pathophysiology. In addition, two potential negative regulators of aromatase expression, chicken ovalbumin upstream promoter transcription factor 2 (COUP-TF2) and prostaglandin E2 receptor subtype EP3 (PGE2EP3), were downregulated in endometriosis epithelial cells, which might result in increased local production of estrogen in endometriosis epithelial cells. Furthermore, three potential candidate genes that might be involved in endometriosis related pain were identified: tyrosine kinase receptor B (TRkB) in endometriosis epithelial cells, and serotonin transporter (5HTT) and mu opioid receptor (MOR) in endometriosis stromal cells were all upregulated. One of the candidate genes, MOR, may be involved in a defective immune system in endometriosis. This study has provided new insights into endometriosis pathophysiology.

Endometriosis↗

PubMed2004

Expression of EBAG9/RCAS1 is associated with advanced disease in human epithelial ovarian cancer.

Oestrogen receptor-binding fragment associated gene 9, EBAG9, is an oestrogen-responsive gene that was identified in MCF-7 human breast carcinoma cell line. It is identical to RCAS 1, a cancer cell surface antigen possibly involved in immune escape. In the present study, we examined the expression of EBAG9/RCAS1 in human epithelial ovarian cancer using immunohistochemistry, immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR). A total of 90 epithelial ovarian cancer cases were examined immunohistochemically by means of the antibodies for EBAG9 and ERalpha. The correlation between EBAG9 immunoreactivity and clinicopathological parameters was examined. mRNA expression of EBAG9 and ERalpha were evaluated by RT-PCR in 22 cases. The expression for EBAG9 and ERalpha was examined by immunoblotting in 12 ovarian cancer cell lines. EBAG9 immunoreactivity was detected in the surface and cytoplasm of carcinoma cells in 46 out of 90 cases (51.1%). EBAG9 expression was significantly higher in serous histology (P=0.0402) and advanced disease (P=0.0206). No significant relationship was detected between EBAG9 immunoreactivity and overall survival (P=0.689). There was a highly significant correlation between EBAG9 and ER immunoreactivity (P<0.0001). The EBAG9 mRNA was detected in 20 out of 22 cases. In all of the cases that were positive for ERalpha mRNA, they were also positive for EBAG9 mRNA. Immunoreactive band corresponding to EBAG9 was detected in 11 out of 12 of ovarian cancer cell lines, and was consistent with ERalpha expression. In conclusion, the wide distribution of EBAG9 and its relation to advanced disease suggest that this protein may play important roles in epithelial ovarian cancer.

Antigens, Neoplasm↗

PubMed2004

Elevated bone resorption markers in a patient with hypercalcemia associated with post-partum thyrotoxicosis and hypoadrenocorticism due to pituitary failure.

A 36-yr-old woman began to suffer from headache, anorexia and general fatigue at 35 weeks' gestation. About 2 or 3 months after the delivery, fever, tachycardia and generalized musculoskeletal disorder appeared. Thereafter, they worsened rapidly, accompanied by a disturbance of consciousness and hypercalcemia. Thyrotoxicosis, due to a post-partum thyroiditis, and glucocorticoid deficiency, due to a pituitary failure, probably associated with lymphocytic hypophysitis, were also observed. All the symptoms and hypercalcemia disappeared after the glucocorticoid replacement therapy and the normalization of thyroid hormone levels. Serum and urinary bone resorption markers, such as urine pyridinoline (U-Pyr), urine deoxypyridinoline (U-DPD), urine amino-terminal telopeptide of type I collagen (U-NTx) and serum carboxy-terminal telopeptide of type I collagen (ICTP), were extremely high at the hypercalcemic state. In this case, they were 10 to 20 times higher than the normal upper limits, and then markedly decreased in a normocalcemic state, thereby showing an extreme acceleration of bone resorption in a state of both thyrotoxicosis and glucocorticoid deficiency.

Adrenal Insufficiency↗

PubMed2004

Pulmonary thromboembolism following gynecologic surgery and cesarean section.

OBJECTIVE: To investigate the incidence and risk factors of symptomatic pulmonary thromboembolism (PTE) in patients following gynecologic surgery or cesarean section in Japan. METHOD: We examined the clinical records of all patients who have undergone gynecologic surgery or cesarean section at 32 hospitals affiliated with the Tohoku University Hospital between 1990 and 1999. RESULT: The total number of gynecologic surgical procedures and cesarean sections were 61648 and 26502, respectively. Twenty-five of the 88150 (0.028%) patients developed clinical PTE. Among the PTE patients who underwent gynecologic surgery, 86% were more than 40 years of age, 36% were obese (BMI>25 kg/m(2)) and 43% had uterine body cancer. Among the PTE patients who underwent cesarean section, 36% were more than 35 years of age and 55% were obese (BMI>29 kg/m(2)). CONCLUSION: Risk factors in Japanese patients undergoing gynecologic surgery may include age and cancer of the uterine body; risk factors for the development of PTE following cesarean section may include age and obesity.

Adult↗

PubMed2004

Avulsion fracture of peroneus longus at the first metatarsal insertion: a case report.

Reports of isolated avulsion fracture at the planter lateral base of the first metatarsal without injury of the tarsometatarsal joint are very rare. A 24 year old man sustained an avulsion fracture at the plantar lateral base of the first metatarsal. Normal alignment of metatarsal bones and tarsometatarsal joint was maintained. In this paper, we describe internal fixation of the displaced fragment using x ray and minimally invasive surgery with good results.

Adult↗