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K Ichimura

Publications and source records attributed to K Ichimura.

At least 19 recordsLinked to original sources
PubMed2006

Search for the invisible decay of neutrons with KamLAND.

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.

Journal Article↗
PubMed2006

Small regions of overlapping deletions on 6q26 in human astrocytic tumours identified using chromosome 6 tile path array-CGH.

Deletions of chromosome 6 are a common abnormality in diverse human malignancies including astrocytic tumours, suggesting the presence of tumour suppressor genes (TSG). In order to help identify candidate TSGs, we have constructed a chromosome 6 tile path microarray. The array contains 1,780 clones (778 P1-derived artificial chromosome and 1,002 bacterial artificial chromosome) that cover 98.3% of the published chromosome 6 sequences. A total of 104 adult astrocytic tumours (10 diffuse astrocytomas, 30 anaplastic astrocytomas (AA), 64 glioblastomas (GB)) were analysed using this array. Single copy number change was successfully detected and the result was in general concordant with a microsatellite analysis. The pattern of copy number change was complex with multiple interstitial deletions/gains. However, a predominance of telomeric 6q deletions was seen. Two small common and overlapping regions of deletion at 6q26 were identified. One was 1,002 kb in size and contained PACRG and QKI, while the second was 199 kb and harbours a single gene, ARID1B. The data show that the chromosome 6 tile path array is useful in mapping copy number changes with high resolution and accuracy. We confirmed the high frequency of chromosome 6 deletions in AA and GB, and identified two novel commonly deleted regions that may harbour TSGs.

Astrocytoma↗
PubMed2005

Experimental investigation of geologically produced antineutrinos with KamLAND.

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

Journal Article↗
PubMed2005

Mutations in Rb1 pathway-related genes are associated with poor prognosis in anaplastic astrocytomas.

Anaplastic astrocytoma (AA, WHO grade III) is, second to Glioblastoma, the most common and most malignant type of adult CNS tumour. Since survival for patients with AA varies markedly and there are no known useful prognostic or therapy response indicators, the primary purpose of this study was to examine whether knowledge of the known genetic abnormalities found in AA had any clinical value. The survival data on 37 carefully sampled AA was correlated with the results of a detailed analysis of the status of nine genes known to be involved in the development of astrocytic tumours. These included three genes coding for proteins in the p53 pathway (TP53, p14(ARF)and MDM2), four in the Rb1 pathway (CDKN2A, CDKN2B, RB1 and CDK4) and PTEN and EGFR. We found that loss of both wild-type copies of any of the three tumour suppressor genes CDKN2A, CDKN2B and RB1 or gene amplification of CDK4, disrupting the Rb1 pathway, were associated with shorter survival (P=0.009). This association was consistent in multivariate analysis, including adjustment for age (P=0.013). The findings suggest that analysis of the genes coding for Rb1 pathway components provides additional prognostic information in AA patients receiving conventional therapy.

Adolescent↗
PubMed2005

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion.

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

Journal Article↗
PubMed2004

Effect of total knee arthroplasty on patients' bone quality-ultrasound measurement of the calcaneus.

We used ultrasonographic heel measurements to compare the bone quality of patients who underwent total knee arthroplasty (TKA), age-matched controls and patients who suffered from hip fracture. The broadband ultrasound attenuation (BUA; dB/MHz) of the TKA (70), control (70) and hip fracture (107) groups was 42.2+/-15.5, 40.2+/-14.9 and 22.9+/-13.3, respectively. The hip fracture group was significantly different from both the TKA and control groups (P<0.0001). The TKA group had better BUA than the control group, although the difference was not significant (P=0.712). The increase in activity after artificial replacement of an arthritic joint might result in bone quality equivalent to that of controls. Considering that none of TKA patients suffered from hip fracture in the follow-up period, which ranged from 62 to 113 months, TKA might contribute to a decrease in the risk of later hip fracture, by allowing increased mobility and maintaining or improving bone quality.

Aged↗
PubMed2004

Amelioration by active hexose correlated compound of endocrine disturbances induced by oxidative stress in the rat.

OBJECTIVE: Active hexose correlated compound (AHCC), an extract derived from fungi of Basidiomycetes family, has been found to be a potent antioxidant. Since the secretion of some hormones can be affected by reactive oxygen species, the objective of this study was to examine how ferric nitrilotriacetate (FeNTA), which generates hydroxyl radicals in vivo, modulates the hormone secretion and the effects of AHCC. METHODS: AHCC at 3 % in drinking water was given to male rats for one week, and the animals were decapitated at different time intervals after the treatment with FeNTA intraperitoneally. Serum levels of hormones (corticosterone, testosterone, thyroxine and triiodothyronine), adrenal ascorbic acid as well as changes in hepatic oxidative status were evaluated by immunoassay and spectrometry. RESULTS: Serum corticosterone levels increased significantly following FeNTA treatment, while AHCC reduced the increased levels to normal. Adrenal ascorbic acid levels that reflect ACTH secretion, were decreased by FeNTA and restored to normal by AHCC. Serum levels of testosterone and thyroxine (T4) decreased rapidly after FeNTA treatment, while AHCC pretreatment prevented this fall. Serum triiodothyroxine (T3) levels remained unchanged either by FeNTA or AHCC treatment. The hepatic oxidized glutathione, glutathione-related enzymes and also serum lipid peroxide were greatly enhanced after FeNTA treatment. All of these changes were restored to normal by AHCC pretreatment. CONCLUSION: FeNTA induces various endocrine disorders and AHCC ameliorates these effects by acting as an antioxidant.

Animals↗
PubMed2003

Suicide gene therapy using AAV-HSVtk/ganciclovir in combination with irradiation results in regression of human head and neck cancer xenografts in nude mice.

The application of adeno-associated virus (AAV) vectors to cancers is limited by their low transduction efficiency. Previously, we reported that gamma-ray enhanced the second-strand synthesis, leading to the improvement of the transgene expression, and cytocidal effect of the herpes simplex virus type-1 thymidine kinase (HSVtk) and ganciclovir (GCV) system. In this study, we extended this in vitro findings to in vivo. First, the laryngeal cancer cell line (HEp-2) and HeLa were treated with AAVtk/GCV, the number of surviving cells was reduced as the concentration of GCV increased. Furthermore, the 4 Gy irradiation enhanced the killing effects of AAVtk/GCV by four-fold on HeLa cells and 15-fold on HEp-2 cells. Following the in vitro experiments, we evaluated the transgene expression and the antitumor activity of the AAV vectors in combination with gamma-ray in nude mice inoculated with HEp-2 subcutaneously. The LacZ expression was observed in the xenografted tumors and significantly increased by gamma-ray. The AAVtk/GCV system suppressed the tumors growth, and gamma-ray augmented the antitumor activity by five-fold. These findings suggest that the combination of AAVtk/GCV system with radiotherapy is significantly effective in the treatment of cancers and may lead to reduction of the potential toxicity of both AAVtk/GCV and gamma-ray.

Animals↗
PubMed2003

Coumestrol as well as isoflavones in soybean extract prevent bone resorption in ovariectomized rats.

OBJECTIVE: Soybeans contain an abundance of phytoestrogens such as genistein and daidzein, and these compounds are thought to protect against bone loss under estrogen deficient conditions. It is possible, however, that phytoestrogens other than isoflavones may suppress bone resorption. The objective of the present study was to determine whether there are any phytoestrogens other than isoflavones in soybeans that can act as antiosteoporotic agents. METHODS: The isoflavones genistein and daidzein, and an extract of soybeans that contained very low levels of isoflavones were tested for their ability to reduce bone resorption in ovariectomized rats. The extract of soybeans was further analyzed for its main components by thin layer chromatography and gas chromatography-mass spectrometry. RESULTS: The soybean extract, as well as the two isoflavones, were effective to reduce urinary excretion of deoxypyridinoline and pyridinoline, typical markers of bone resorption in ovariectomized rats. However the extract, unlike the isoflavones, increased the uterine weight of ovariectomized rats significantly. Analysis by thin-layer and gas chromatography revealed that the main constituent of this extract exhibited a chromatographic profile corresponding to coumestrol. This substance was positively identified as coumestrol by gas chromatography-mass spectrometry. CONCLUSION: These results suggest that the phytoestrogens including coumestrol and isoflavones in soybeans may exert effective prevention against bone resorption in estrogen deficient conditions.

Amino Acids↗
PubMed2001

Cloning and chromosomal localization of human WIG-1/PAG608 and demonstration of amplification with increased expression in primary squamous cell carcinoma of the lung.

In this report, we describe the cloning of the coding region of human WIG-1 cDNA. The human 8 and 6 kb WIG-1 transcripts are both upregulated following ionizing irradiation of the human colon cancer cell lines HCT116 and LoVo which have wild type TP53 but not in DLD1 cells that lack wild type TP53. Basal levels of both WIG-1 transcripts were detected in human adult brain, kidney, and testis, but not in fetal brain, heart, pancreas, adrenal gland, fetal liver, and small intestine. FISH analysis mapped the human WIG-1 gene to 3q26.3. Investigation of squamous cell carcinomas of the lung by Southern blot and semiquantitative RT-PCR analysis showed amplification in combination with increased expression of WIG-1 in 1/7 tumors and increased expression in a further two cases.

Amino Acid Sequence↗
PubMed2001

Caspase-3-deficiency induces hyperplasia of supporting cells and degeneration of sensory cells resulting in the hearing loss.

Caspase-3 is one of the cystein proteases that play essential roles in programmed cell death. As such, brain development is profoundly affected by caspase-3-deficiency, resulting in hyperplasia and abnormal cell organization (Kuida et al., Nature 1996;384:368-372). In the present study, we used caspase-3 (-/-) mice to show that caspase-3 deficiency results in severe hearing loss, hyperplasia of supporting cells and degeneration of sensory hair cells. The greater epithelial ridge, a remnant of the primordial organ of Corti, persists throughout all of the turns of cochlea in 2-week-old caspase-3 (-/-) mice, which indicates that the morphology of the cochlea is immature. The number of border cells, that develop from the greater epithelial ridge and are one of the supporting cells of the inner hair cell, increase significantly in both 2- and 5-week-old caspase-3 (-/-) mice. On the other hand, abnormal fused stereocilia can be seen in both 2- and 5-week-old caspase-3 (-/-) mice, and disarrangement and loss of sensory hair cells are observed in 5-week-old caspase-3 (-/-) mice. Taken together, both hyperplasia and degeneration occur simultaneously in the inner ear of the caspase-3 (-/-) mice, suggesting that caspase-3-dependent apoptosis is necessary for the development and formation of a properly functioning auditory system in mammals.

Animals↗
PubMed2001

Multiple organ mucosa-associated lymphoid tissue lymphomas often involve the intestine.

BACKGROUND: Low grade mucosa-associated lymphoid tissue (MALT) lymphomas usually are confined to single extranodal organs. Although some case reports have been published, clinicopathologic characteristics of multiorgan MALT lymphomas remain unclear. METHODS: The authors evaluated 7 MALT lymphoma cases involving multiorgans in the past 7 years. In this period, they experienced 304 cases of MALT lymphomas. They analyzed the clinicopathologic features of these cases, including examination of clonal comparison among the lesions. RESULTS: The patients, 4 females and 3 males, were aged 55-68 years old (average, 60.1 years). Four cases showed multiple organ involvement at the initial diagnosis or after a short period. In the other three cases, primary foci were the stomach, thyroid gland, and ocular adnexa; after a rather long period (3 years or more), distant metastases were found. Although intestinal primary lymphomas are rather rare, six of the seven cases showed large intestinal involvement. Lymph node involvement was proven in only three cases. The patients were rather resistant to the various therapeutic approaches. Although six patients are alive, five are with disease. DNA analyses revealed that in five of the cases evaluated, identical clones were detected among the different affected organs. CONCLUSIONS: Multiorgan MALT lymphomas are rather rare. Most cases probably derived from a single clone, and lymphoma cells may selectively move among MALTs via a homing system with preferential involvement of the colon. Because multiorgan MALT lymphomas rarely achieve complete remission by treatment with combination chemotherapy or irradiation, MALT lymphomatous lesions should be checked carefully, especially in the large intestine.

Aged↗
PubMed2001

Peripheral T/natural killer-cell lymphoma involving the female genital tract: a clinicopathologic study of 5 cases.

Malignant lymphoma of the female genital tract (FGT) is rare. In this study, 5 peripheral T/natural killer (NK)-cell lymphomas (PTCLs) involving the FGT are reported. They include 2 from the uterus and 1 each from ovary, uterus and ovary, and vagina, and were detected between 1996 and 2000. One of the 2 ovarian tumors was bilateral. In all cases, the FGT was the initial site of clinical presentation of disease. Age at presentation ranged from 21 to 52 years (median, 36 years). One case was stage I disease, 2 were stage II, and 2 were stage IV. All 5 tumors were positive for CD3epsilon, and 3 harbored the Epstein-Barr virus, although the detailed immunophenotypic profiles varied. Three were diagnosed as nasal type T/NK-cell lymphoma, 1 as anaplastic large-cell lymphoma (anaplastic lymphoma kinase [ALK]-positive), and 1 as unspecified PTCL of cytotoxic phenotype, according to the forthcoming World Health Organization classification. Four of 5 patients received laparotomy and chemotherapy. Four patients (in stages II and IV) died of disease within 16 months of the initial diagnosis, whereas only 1 patient (in stage I) is alive without disease at 39 months of follow-up. Our experience in this series provided clinically relevant information on diagnosis, treatment, and outcome for extremely rare tumors of the FGT.

Adult↗
PubMed2001

Concurrent Hodgkin's disease (mixed cellularity type) and T-cell chronic lymphocytic leukemia/prolymphocytic leukemia.

We describe a patient with leukopenic T-cell chronic lymphocytic leukemia/prolymphocytic leukemia (T-CLL/PLL), according to the Revised European-American Classification of Lymphoid Neoplasms. This patient simultaneously developed classic Hodgkin's disease (HD), a combination previously unreported. The leukemic cells were small and mature, did not have cytoplasmic granulation, and appeared similar to B-cell chronic lymphocytic leukemia. Immunophenotyping of the bone marrow-infiltrating cells revealed a postthymic suppressor/cytotoxic phenotype of CD2+, CD3+, CD4, CD5+, CD8+, CD25-, TCR-alpha beta. A lymph node biopsy showed the histological features of HD (mixed cellularity) with infiltrating CD8+ lymphocytes, and immunohistochemical examination revealed the following phenotype of Reed-Sternberg cells: LeuM1/CD15+, BerH2/CD30+, L26/PanB-, UCHL-1/CD45RO-, cyCD3-, CD4, CD8-, CD20-, CD79a-, EMA-, EBER-1+, LMP-1+. Southern blot analysis of the bone marrow and lymph node revealed the same rearrangement of bands of T-cell-receptor genes. Although the HD was treated with chemotherapy that resulted in complete remission, the T-PLL/CLL took an indolent course. This case may suggest the existence of a subtype of T-CLL/PLL with leukopenia and an indolent clinical course. Both diseases were believed to be independent and not a transformation of one to the other.

Aged↗
PubMed2001

Pregnancy-associated cytotoxic lymphoma: a report of 4 cases.

The clinicopathological and biological significance of Hodgkin's disease and non-Hodgkin's lymphoma, which are infrequently encountered in women of childbearing age, remains to be clarified. We recently reviewed 4 cases of non-Hodgkin's lymphoma of the T/natural killer (T/NK)-cell phenotype, all of which were associated with pregnancy and characterized by the expression of the cytotoxic granule-associated proteins T-cell intracellular antigen-1 and/or granzyme B. The 4 cases selected had presented between November 1993 and May 1999. The criteria for selection were that the onset of clinical manifestations occurred during pregnancy or within 6 months after delivery. The patients comprised 1 patient with p80/anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL), 1 with p80/ALK-negative ALCL, and 2 with peripheral T/NK-cell lymphomas of unspecified type. The diseases followed aggressive clinical courses: 3 patients died within 6.5 months after diagnosis, and only 1 was still alive with the disease 17 months after diagnosis. The diseases appeared to progress rapidly after delivery. Maternal immunity and hormonal changes during pregnancy may be closely related to the biological behavior of these unusual tumors. This study is, to the best of our knowledge, the first to address pregnancy-associated cytotoxic lymphoma.

Adult↗
PubMed2001

Upregulation of histidine decarboxylase mRNA expression in scleroderma skin.

The involvement of histamine in the pathogenesis of systemic sclerosis (SSc) has been suggested. Possible involvement of histamine and histidine decarboxylase (HDC), the synthesizing enzyme for histamine, in the formation of the skin abnormalities in SSc was studied. Skin histamine concentrations in SSc were significantly lower than in normal controls (P < 0.02). In situ hybridization with an HDC probe revealed that the expression of the HDC gene in SSc was greater than in normal controls. The number of cells and the mean grain number per cell expressing HDC mRNA were both significantly greater in SSc than in normal controls (both P < 0.01). These results show a reduction in histamine concentration and an elevated HDC gene expression in SSc skin, indicating an increase in both histamine release and HDC gene expression. The upregulation of histamine turnover appears to be involved in the formation of the skin abnormalities of SSc.

Adult↗
PubMed2001

Alterations of the tumor suppressor genes CDKN2A (p16(INK4a)), p14(ARF), CDKN2B (p15(INK4b)), and CDKN2C (p18(INK4c)) in atypical and anaplastic meningiomas.

We investigated 67 meningothelial tumors (20 benign meningiomas, 34 atypical meningiomas, and 13 anaplastic meningiomas) for losses of genetic information from chromosome arms 1p and 9p, as well as for deletion, mutation, and expression of the tumor suppressor genes CDKN2A (p16(INKa)/MTS1), p14(ARF), CDKN2B (p15(INK4b)/MTS2) (all located at 9p21) and CDKN2C (1p32). Comparative genomic hybridization and microsatellite analysis showed losses on 1p in 11 anaplastic meningiomas (85%), 23 atypical meningiomas (68%), and 5 benign meningiomas (25%). One atypical meningioma with loss of heterozygosity on 1p carried a somatic CDKN2C mutation (c.202C>T: R68X). Losses on 9p were found in five anaplastic meningiomas (38%), six atypical meningiomas (18%), and one benign meningioma (5%). Six anaplastic meningiomas (46%) and one atypical meningioma (3%) showed homozygous deletions of the CDKN2A, p14(ARF), and CDKN2B genes. Two anaplastic meningiomas carried somatic point mutations in CDKN2A (c.262G>T: E88X and c.262G>A: E88K) and p14(ARF) (c.305G>T: G102V and c.305G>A: G102E). One anaplastic meningioma, three atypical meningiomas, and one benign meningioma without a demonstrated homozygous deletion or mutation of CDKN2A, p14(ARF), or CDKN2B lacked detectable transcripts from at least one of these genes. Hypermethylation of CDKN2A, p14(ARF), and CDKN2B could be demonstrated in one of these cases. Taken together, our results indicate that CDKN2C is rarely altered in meningiomas. However, the majority of anaplastic meningiomas either show homozygous deletions of CDKN2A, p14(ARF), and CDKN2B, mutations in CDKN2A and p14(ARF), or lack of expression of one or more of these genes. Thus, inactivation of the G(1)/S-phase cell-cycle checkpoint is an important aberration in anaplastic meningiomas.

Adult↗