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N Yahata

Publications and source records attributed to N Yahata.

At least 19 recordsLinked to original sources
PubMed2006

A functional MRI study: cerebral laterality for lexical-semantic processing and human voice perception.

BACKGROUND AND PURPOSE: Language dominance research using functional neuroimaging has made important contributions to clinical applications. Nevertheless, although recent neuroimaging studies demonstrated right-lateralized activation by human voice perception, the influence of voice perception in terms of language dominance has not been adequately studied. We aimed to accurately clarify language dominance for lexical-semantic processing in the temporal cortices by focusing on human voice perception. METHODS: Thirty normal right-handed subjects were scanned by functional MR imaging while listening to sentences (SEN), reverse sentences (rSEN), and identifiable nonvocal sounds (SND). We investigated cerebral activation and the distribution of individual Laterality Index under 3 contrasts: rSEN-SND, SEN-SND, and SEN-rSEN. RESULTS: The rSEN-SND contrast, including human voice perception, revealed right-lateralized activation in the anterior temporal cortices. Both SEN-SND and SEN-rSEN contrasts, including lexical-semantic processing, showed left-lateralized activation in the inferior and middle frontal gyrus and middle temporal gyrus. The SEN-rSEN contrast, without the influence of human voice perception, showed no temporal activation in the right hemisphere. Symmetrical or right-lateralized activation was observed in 22 of 27 subjects (81.4%) under the rSEN-SND contrast in the temporal cortices. Although 9 of 27 subjects (33.3%) showed symmetrical or right-lateralized activation under the SEN-SND contrast in the temporal cortices, all subjects showed left-lateralized activation under the SEN-rSEN contrast. CONCLUSION: Our results demonstrated that right-lateralized activation by human voice perception could mask left-lateralized activation by lexical-semantic processing. This finding suggests that the influence of human voice perception should be adequately taken into account when language dominance is determined.

Adult↗
PubMed2001

In situ telomerase activity in pleural effusions: a promising marker for malignancy.

Telomerase activity in 16 pleural effusions was studied using an in situ telomerase repeat amplification protocol (TRAP) assay on cytospin preparations. Six of nine cytologically malignant specimens contained telomerase-positive cells (67%), and in two further specimens, suspicious positive cells were seen. Two of four atypical specimens contained telomerase-positive cells, whereas two benign cases were telomerase-negative. No mesothelial cells showed telomerase reactivity. Thus, telomerase activity was specific for malignancy and it was always found only in malignant cells. The results suggest that telomerase activity measured with this in situ method can be a valuable complement in the assessment of malignancy in pleural effusions.

Biomarkers, Tumor↗
PubMed2001

MALT lymphoma originating in breast and uvula.

A case of marginal zone B cell lymphoma of MALT type arising in the uvula and breast is reported. The patient, a 30-year-old woman who delivered a child and lactated in 1997, was suffering from Sjögren syndrome (SS). She was diagnosed with MALT lymphoma after a biopsy of the right breast and uvula. To investigate the relationship of the delivery, lactation and MALT lymphoma, we examined the immunohistochemical analysis of hormone receptors. As a result, lymphoid cells of the breast were stained with anti-progesterone receptor antibodies in the cytoplasm. Consequently, the MALT lymphoma of the uvula appeared to be associated with SS. Moreover, hormones such as progesterone may have influenced the breast involvement of MALT lymphoma in our case.

Adult↗
PubMed2001

Telomere dynamics in myelodysplastic syndromes and acute leukemic transformation.

Myelodysplastic syndromes (MDS) are characterized by cytopenias in the blood and dysplastic features in the hematopoietic cells. Although the impact of cytogenetic abnormalities is considerable for prognosis, the exact genetic mechanism of MDS remains undetermined. In this study we assessed cytogenetic changes, microsatellite alterations, and telomere dynamics in order to obtain further insight into the pathogenesis of MDS. Thirty-three percentage of MDS patients and 60% of post-MDS acute leukemia (post-MDS AML) had de novo microsatellite changes. In the MDS phase, however, > 60% of patients showed reduction of telomere lengths without microsatellite changes, indicating that telomere reduction in most MDS patients does not seem to be directly linked to genome instability, or that reduction of telomere length does not induce microsatellite changes in the MDS phase. Some MDS patients had microsatellite changes without telomerase elevation, indicating that genome instability might accumulate during the disease progression in some MDS patients, and this condition (cellular senescence) may be related to ineffective hemopoiesis in MDS patients. In contrast, 40% of post-MDS AML patients had elevated telomerase activity with microsatellite changes, indicating that approximately 40% of patients with post-MDS AML patients had accumulation of genome instability resulting in elevated telomerase activity in an attempt to obtain genetic stability. However, the remaining MDS patients had microsatellite changes without telomerase up-regulation, suggesting that some MDS had genome instability even after leukemic transformation. Most MDS patients with elevated telomerase activity in the AML phase had elevated telomerase activity even in the MDS phase without apparent change in telomere length before and after leukemic transformation. These findings indicate that telomerase activity in the MDS phase may be independent of telomere length, although telomere shortening seems to be related to genomic instability, and this process may be linked to apoptosis of MDS cells.

Cell Transformation, Neoplastic↗
PubMed2001

Impaired telomere regulation mechanism by TRF1 (telomere-binding protein), but not TRF2 expression, in acute leukemia cells.

Telomere regulation is suggested to be an important mechanism in cellular proliferation and cellular senescence not only in normal diploid cells but also in neoplastic cells, including human leukemia cells. We studied the possible correlation among telomere length, telomerase (a ribonuclear protein that synthesizes the telemeres de novo) activity, hTERT (a catalytic subunit of telomerase) expression, and TRF1 and TRF2 (telomere DNA binding proteins) expression in human acute leukemia cells. The hTERT expression level was strongly associated with telomerase activity (P=0.0001), indicating that the expression level of the catalytic subunit (hTERT) regulates telomerase activity in human acute leukemia cells. TRF1 expression, which is believed to control telomere length, was significantly elevated in patients with acute lymphoblastic leukemia (ALL) (P=0.0232) compared to those in acute myeloid leukemia (AML); TRF1 expression tended to be higher in patients without telomere shortening (P=0.077) and in those with hTERT expression (P=0.055). This indicates that TRF1 may act to monitor telomere length under the condition of up-regulated telomerase activity in some neoplastic cells. In contrast, TRF2 expression in acute leukemia did not show any correlation with telomere parameters in this study. Although the precise regulation mechanism of telomere length is still uncertain, these results may suggest that regulation of telomere length is partially associated with TRF1 expression, whereas dysfunction of TRF1 expression may be speculated in a subset of acute leukemia.

Adolescent↗
PubMed2000

Unusual spectral energy distribution of a galaxy previously reported to be at redshift 6.68.

Observations of distant galaxies are important both for understanding how galaxies form and for probing the physical conditions of the Universe at early times. It is, however, very difficult to identify galaxies at redshifts z > 5, because they are so faint and have few spectral characteristics. We previously reported the probable identification of a galaxy at z = 6.68, based on one line and an apparent break in the spectrum just shortwards of that, which we interpreted as Lyman alpha emission and the Lyman alpha break, where photons with shorter wavelengths are absorbed by the intervening neutral hydrogen gas. Here we present optical photometry that shows moderate detections of light in the B- and V-band images, which are inconsistent with the expected absence of flux shortwards of the Lyman alpha break for alpha galaxy at z > 5, and inconsistent with the previous flux measurement. Moreover, the spectral energy distribution for this object cannot readily be fitted by any known galaxy spectral template at any redshift, so the redshift is undetermined.

Journal Article↗
PubMed2000

Correlation between morphology and telomerase activity in cells from exfoliative lung cytologic specimens.

BACKGROUND: Telomerase is a ribonucleoprotein that compensates for the erosion of telomeres (chromosomal termini). Telomerase activity is detected in more than 85% of cancerous lesions and is therefore considered a novel marker of cancer. The authors compared cytologic morphology and telomerase activity at the cellular level to obtain further insight into their association. METHODS: The authors used bronchial washing and brushing materials obtained from 18 patients with lung carcinomas (6 squamous cell, 8 adenocarcinoma, 2 large cell, 1 small cell, and 1 metastasis from colon carcinoma) and 20 patients with nonmalignant disease. An in situ telomeric repeat amplification protocol (TRAP) assay was performed, and routine Papanicolaou-stained slides using the same sample were assessed. RESULTS: Nuclear fluorescent signals at the nuclear area, corresponding to telomerase activity, shown by the in situ TRAP assay were only detected in samples containing morphologically malignant cells. No nuclear fluorescence was seen in the keratinizing component of well-differentiated squamous cell carcinoma. Nuclear staining was not seen in metaplastic or basal hyperplastic cells. Cytoplasmic fluorescence was only found in macrophages and polymorphonuclear leukocytes. CONCLUSIONS: Nuclear fluorescence corresponding to telomerase activity was not demonstrated in metaplastic or basal hyperplastic cells, thus indicating that detection of telomerase activity is closely associated with the presence of malignant cells, but not premalignant lesions, in lung carcinoma patients. Moreover, in some samples with cancer, cells failed to show telomerase activity, suggesting the limitation of this method for the detection of malignant cells in certain lung carcinoma patients.

Adenocarcinoma↗
PubMed2000

Interleukin 6 receptor expression by human cord blood- or peripheral blood-derived primitive haematopoietic progenitors implies acquisition of different functional properties.

The significance of interleukin 6 receptor (IL-6R) expression by cord blood (CB)- and peripheral blood (PB)-derived primitive haematopoietic progenitors was investigated. IL-6R was preferentially expressed by PB-derived myeloid progenitors. Most PB-derived erythroid bursts (BFU-E) and mixed colony-forming cells (CFU-Mix) did not express this receptor. However, CB-derived primitive progenitor cells possessed multipotentiality, irrespective of IL-6R expression. Interestingly, the long-term culture-initiating cell (LTC-IC) population was enriched in PB-derived CD34+ IL-6R+ cells, but the extended LTC-IC (ELTC-IC) population, which represents a less mature class of haematopoietic progenitors, seemed to be equally distributed in the IL-6R+ and IL-6R- cell populations. In contrast, the number of LTC-ICs and ELTC-ICs was similar in CB-derived CD34+ IL-6R+ or IL-6R- cells. It is noteworthy that the number of LTC-ICs and ELTC-ICs in CB-derived CD34+ cells was markedly higher than that in PB-derived CD34+ cells regardless of IL-6R expression. Telomerase activity was consistently lower in PB-derived CD34+ IL-6R- cells than in CD34+ IL-6R+ cells. In contrast, telomerase activity was similar in CB-derived CD34+ IL-6R+ or IL-6R- cells. The pattern of telomerase induction upon cytokine stimulation differed between CB- and PB-derived CD34+ IL-6R+ or IL-6R- cells. However, overall telomerase activity per dish was well correlated with the proliferative potential of both cell populations, suggesting that induction of telomerase plays an important role in the escape from replicative senescence of primitive haematopoietic progenitors. Collectively, these results suggest that CB-derived primitive progenitors are less mature than PB-derived progenitors and that the expression of IL-6R by primitive haematopoietic progenitors may have different implications for PB- and CB-derived CD34+ cells.

Antigens, CD↗
PubMed2000

Detection of telomerase activity in biopsy specimens for diagnosis of biliary tract cancers.

BACKGROUND: Telomerase activity is detectable in more than 85% of primary cancers. We determined telomerase activity in biopsy specimens obtained from biliary tract cancers to evaluate the clinical application of telomerase activity detection in combination with p53 immunostaining and routine histologic examination. METHODS: Biopsy specimens obtained during percutaneous transhepatic cholangioscopy from 13 patients with cholangiocarcinoma, 3 patients with gallbladder carcinoma, and 4 patients with intrahepatic bile duct stones were evaluated by routine histologic examination, p53 immunostaining, and telomerase activity. Semiquantitative determination of telomerase activity was performed using a fluorescence-based telomeric repeat amplification protocol. RESULTS: Thirteen of 16 specimens of malignant tissue had detectable telomerase activity, whereas no specimen of nonmalignant tissue had detectable telomerase activity. A p53 overexpression was recognized by immunostaining in 9 of 16 samples with cancers. Combining both telomerase activity and p53 overexpression resulted in the detection of all cancer with a sensitivity of 100%. There were no false-positive results by either modality (specificity 100%). CONCLUSIONS: The detection of telomerase activity in biopsy specimens and p53 overexpression in combination with routine histologic examination may improve the diagnosis of biliary tract cancers. (Gastrointest Endosc 2000;52:380-6).

Aged↗
PubMed2000

Chronic lymphocytic leukemia complicated by plasmacytoma originating from different clones.

In a woman with chronic lymphocytic leukemia (CLL), a plasmacytoma developed on the back region after four years. CLL cases complicated with plasmacytoma are rare. In the present case, the plasmacytoma showed kappa cytoplasmic immunoglobulin (Ig), and the CLL showed gamma lambda surface Ig. To reveal the clonal origin of CLL and plasmacytoma, we analyzed Ig gene rearrangements in the patient's peripheral blood and plasmacytoma. Ig gene DNA analysis confirmed the presence of different rearrangements in the heavy and light chain genes of CLL and plasmacytoma. These findings suggest that in this patient, the two B cell malignancies arose from expansion of two phenotypically and genotypically distinct clones.

Blotting, Southern↗
PubMed1999

Expression of telomerase subunits and localization of telomerase activation in hydatidiform mole.

Activation of telomerase compensating for the loss of telomeres has been implicated in human cell immortalization and carcinogenesis. Telomeric repeat amplification protocol (TRAP) assay can be used to detect telomerase activity in a variety of malignant tumours, including those of the female reproductive tract which have been found to have high levels of telomerase activity. However, it is unclear whether all the cells or only a subset of cells within a tumour have telomerase activity. To determine the regulation mechanism of telomerase activity in hydatidiform moles, we studied telomerase activity at the single cell level (using an in situ TRAP assay), and expression of TLP1 (telomerase protein 1), TERC (telomerase RNA component) and TERT (telomerase reverse transcriptase component). Expression of TERC and TLP1 was observed in all normal chorionic villi, as well as in trophoblastic diseases, and various cell lines irrespective of telomerase activity. TERT expression was observed in trophoblastic diseases and normal chorionic villi with telomerase activity but not in normal chorionic villi without telomerase activity, except in some cases in the present series, indicating that TERT expression is closely associated with telomerase activity. Upregulation of TERT expression may thus play an important role in telomerase reactivation.

Carrier Proteins↗
PubMed1999

Improvement in detecting telomerase activity using silica-based resin treatment: An experience of urine in bladder carcinoma.

To improve the telomeric repeat amplification protocol (TRAP) assay to detect telomerase activity using a small amount of sample, we used a resin-column to purify and to concentrate the TS extension DNA sequence. We used 14 samples of naturally voided urine (10 ml) from patients with bladder carcinoma and 9 urine samples from patients with non-malignant urological neoplasias. We used ethylenediamine tetraacetic acid (EDTA) to stabilize telomerase activity and resin treatment to concentrate TS-extended DNA and to exclude PCR inhibitor(s), and then performed extract-based fluorescence TRAP to detect telomerase activity. None of the urinary samples without resin-column treatment had detectable telomerase activity, whereas, in resin-column treated samples, 4/9 (44%) urine samples without EDTA and 9/14 (64%) with EDTA treatment had detectable telomerase activity. A combination of EDTA treatment and resin-column thus may be available to detect telomerase activity using a relatively small amount of secretion fluids, including exfoliated urinary cells.

Adult↗
PubMed1999

Subsequential telomerase activity in exfoliated urinary cells detects recurrent disease in bladder cancer after transurethral resection.

We assessed urinary telomerase activity in bladder cancer patients to provide additional information for monitoring after transurethral resection (TUR). Urinary telomerase activity was detected in 22/26 (84.6%) patients with known bladder tumor before TUR. Ten of 11 patients who were available for sequential follow-up examination had urinary telomerase activity before TUR. In 4 of the 10 patients, urinary telomerase activity disappeared following TUR with or without adjuvant intravesical therapy. Three of the remaining 6 patients had recurrent bladder tumors within three months after TUR. Urinary telomerase activity analysis from patients after TUR provides important information on microscopic recurrent bladder cancer.

Aged↗
PubMed1999

Detection of telomerase activity in exfoliated cancer cells obtained from bile.

Telomerase is detected by the telomeric repeat amplification protocol (TRAP) assay in more than 85% of primary cancers. In the present study, we determined telomerase activity using exfoliated bile cells obtained from biliary tract neoplasia specimens. The aim of this study was to provide additional information regarding minimally invasive approaches to the detection of biliary tract cancer in combination with routine cytologic examination. We analyzed for telomerase activity bile juice from patients with gallbladder carcinoma, cholangiocarcinoma, cholecystitis and cholangitis. Semiquantitative determination of telomerase activity was performed using both a fluorescence-based TRAP assay on cell extracts and at the cellular level by an in situ TRAP assay. The fluorescence-based TRAP assay detected bile telomerase activity in samples from 4 of 10 patients with biliary tract cancer. In contrast, the in situ TRAP assay detected telomerase positive cells in samples from 6 of 10 patients with biliary tract cancer. However, only one of these samples showed class V cytology. A combination of semiquantitative analysis and an in situ TRAP assay to detect telomerase positive cells may improve the diagnosis of biliary tract cancers with the combination of routine cytologic examination.

Adult↗
PubMed1999

Telomere stability is frequently impaired in high-risk groups of patients with myelodysplastic syndromes.

Genomic instability induces an accumulation of genetic changes and may play a role in the pathogenesis of myelodysplastic syndromes (MDS). To clarify the possible association between genomic instability and clinical outcome in MDS patients, we compared telomere dynamics to the recently established International Prognostic Scoring System (IPSS) risk groups for MDS. We measured the terminal restriction fragments (TRFs) of 93 patients with MDS at the time of diagnosis, and telomerase activity was analyzed in 62 patients with MDS using the PCR-based telomeric repeat amplification protocol (TRAP) assay. A total of 53 of 93 MDS patients had TRFs within the age-matched normal range, and the remaining patients showed shortened TRFs (35 patients) or elongated TRFs (5 patients). MDS patients with shortened TRFs had a significantly low hemoglobin concentration (P = 0.04), a high percentage of marrow blasts (P = 0.02), and a high incidence of cytogenetic abnormalities (P < 0.05). The incidence of leukemic transformation was significantly high in patients with shortened TRF length (P < 0.05). In addition, patients with shortened TRF length were frequently seen in the IPSS high-risk group (P < 0.01). Most of the MDS patients had normal-to-low levels of telomerase activity, suggesting that changes in TRF length rather than telomerase activity may more accurately reflect the pathophysiology of MDS. MDS patients with shortened TRF length had a very poor prognosis (P < 0.01), suggesting that telomere dynamics may be linked to clinical outcome in MDS patients. Thus, an abnormal mechanism of telomere maintenance in subgroups of MDS patients may be an early indication of genomic instability. This study demonstrates that telomere stability is frequently impaired in a high-risk group of MDS patients and suggests that, in combination with the IPSS classification system, measurement of TRFs may be useful in the future to stratify MDS patients according to risk and manage the care of MDS patients.

Acute Disease↗
PubMed1999

[Hypereosinophilic syndrome complicated by myelofibrosis].

Hypereosinophilic syndrome (HES) with myelofibrosis was diagnosed in a 36-year-old man on the basis of bone marrow biopsy findings and clinical features. Although the patient was treated with steroid (1 mg/kg), hydroxyurea, and immunosuppressive therapy, eosinophilia persisted. Patients with HES and myelofibrosis are usually unresponsive to antineoplastic agents and/or immunosuppressants. However, cyclosporin may be an effective alternative for such patients.

Adult↗
PubMed1998

A combination of semiquantitative telomerase assay and in-cell telomerase activity measurement using exfoliated urothelial cells for the detection of urothelial neoplasia.

BACKGROUND: Telomerase is a ribonucleoprotein that synthesizes telomeres. It is detected in more than 85% of samples obtained from cancer tissues, including urologic neoplasia. The authors determined telomerase activity semiquantatively and in-cell telomerase activity in exfoliated urothelial cells obtained from urologic neoplasia specimens. The goal of this study was to provide additional information regarding a noninvasive approach to the detection of urologic neoplasia. METHODS: The authors used voided urine from 23 patients with urologic neoplasia, 2 patients with nonmalignant urologic disorders, and 10 normal individuals. Semiquantative determination of telomerase activity was performed using a fluorescence-based telomeric repeat amplification protocol (TRAP), and telomerase activity at the cellular level was determined by an in situ TRAP assay. RESULTS: The fluorescence-based TRAP assay detected urinary telomerase activity in samples from 10 of 13 patients with urologic neoplasia before treatment, whereas urinary cells obtained from 3 of 10 patients (including 1 patient with relapse) during or after treatment had detectable telomerase activity. In contrast, the in situ TRAP assay detected telomerase positive cells in samples from 11 of 13 patients before treatment and 6 of 10 patients during or after treatment. Of note was a dissociation of the results of the fluorescence-based TRAP assay and those of the in situ TRAP assay for some patients. Some patients for whom telomerase activity was not detected with the fluorescence-based TRAP assay had a low frequency of telomerase positive cells in their urine. CONCLUSIONS: A combination of semiquantative analysis and an in situ TRAP assay to detect telomerase positive cells might be a useful tool in the identification and monitoring of patients with urothelial neoplasia.

Adult↗