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Articles by A Takahashi
Total Records ( 6 ) for A Takahashi
  Y Koga , M Yasunaga , A Takahashi , J Kuroda , Y Moriya , T Akasu , S Fujita , S Yamamoto , H Baba and Y. Matsumura
 

To reduce the colorectal cancer (CRC) mortality rate, we have reported several CRC screening methods using colonocytes isolated from feces. Expression analysis of oncogenic microRNA (miRNA) in peripheral blood was recently reported for CRC detection. In the present study, we conducted miRNA expression analysis of exfoliated colonocytes isolated from feces for CRC screening. Two hundred six CRC patients and 134 healthy volunteers were enrolled in the study. miRNA expression of the miR-17-92 cluster, miR-21, and miR-135 in colonocytes isolated from feces as well as frozen tissues was analyzed by quantitative real-time PCR. The expression of the miR-17-92 cluster, miR-21, and miR-135 was significantly higher in CRC tissues compared with normal tissues. The exfoliated colonocytes of 197 CRC patients and 119 healthy volunteers were analyzed because of the presence of sufficient miRNA concentration. miR-21 expression did not differ significantly between CRC patients and healthy volunteers (P = 0.6). The expression of miR-17-92 cluster and miR-135 was significantly higher in CRC patients than in healthy volunteers (P < 0.0001). The overall sensitivity and specificity by using miRNA expression was 74.1% (146/197; 95% confidence interval, 67.4-80.1) and 79.0% (94/119; 95% confidence interval, 70.6-85.9), respectively. Sensitivity was dependent only on tumor location (P = 0.0001). miRNA was relatively well conserved in exfoliated colonocytes from feces both of CRC patients and healthy volunteers. miRNA expression analysis of the isolated colonocytes may be a useful method for CRC screening. Furthermore, oncogenic miRNA highly expressed in CRC should be investigated for CRC screening tests in the future. Cancer Prev Res; 3(11); 1435–42. ©2010 AACR.

  Y Takahashi , A Takahashi , T Kuwahara , T Fujino , K Okubo , S Kusa , A Fujii , A Yagishita , S Miyazaki , T Nozato , H Hikita , K Hirao and M. Isobe
  Background—

We sought to characterize patients with persistent atrial fibrillation (AF) who were successfully treated by ablation targeting the left atrium (LA).

Methods and Results—

Ninety-three patients (58±10 years, 79 male) undergoing ablation of persistent AF were studied. During the first procedure, ablation was performed in the LA and coronary sinus, consisting of pulmonary vein isolation, linear ablation, and electrogram-based ablation. During follow-up after the first procedure, 35 patients (38%) remained free from tachyarrhythmias, 27 patients (29%) had atrial tachycardia, and 31 patients (33%) had AF. Duration of persistent AF according to medical history and whether AF was terminated by ablation were associated with the outcome (P=0.005, P=0.004, respectively). In multivariate analysis, the duration of persistent AF was the only predictor of freedom from AF (sinus rhythm or atrial tachycardia) (odds ratio, 0.80 for a 1-year increase; 95% confidence interval, 0.67 to 0.95; P=0.01). Of 31 patients in whom AF recurred during follow-up, electrogram-based ablation was performed in the right atrium in 26 patients. Sixteen of those patients (62%) remained free from AF during follow-up. Overall, 82% of patients were free from any tachyarrhythmias at 2-year follow-up after a median of 2 procedures.

Conclusions—

Patients with shorter duration of persistent AF were more likely to be free from AF by LA ablation. Right atrial ablation may provide incremental efficacy in patients who are refractory to LA ablation.

  T Tanaka , H Kitamura , A Takahashi , N Masumori and T. Tsukamoto
  Objective

We retrospectively assessed long-term outcomes of chemotherapy for advanced germ cell tumors (GCTs) at our institution.

Methods

Ninety-five consecutive males with advanced GCTs of the testis or extragonadal origin who received chemotherapy between 1980 and 2006 were enrolled. All patients underwent induction chemotherapy including cisplatin.

Results

The median follow-up period was 36.1 months (0 – 288.5) for all patients and 52.6 months (2.2 – 288.5) for the 73 current survivors. Totally, 75 patients (78.9%) achieved complete remission (CR). CR was achieved in 61.1%, 37.9% and 75.0% of the patients after induction therapy, second-line therapy and third-line or more, respectively. As salvage therapy, high-dose chemotherapy was performed in 11 patients (11.7%) and regimens with novel anticancer agents such as paclitaxel and irinotecan were employed for 8 patients (8.5%) from 2003 and later. The era of the treatment, extrapulmonary metastasis and serum -fetoprotein were independent prognostic factors for patients. The 5-year overall survival of patients after 1992 was 83.0%, which was significantly higher than that of those before 1992 (56.3%). CR was never achieved in 20 patients and most of them met the criteria of the poor-prognosis group. Disease recurrence after CR was found in nine patients who were initially classified into the good- or intermediate-prognosis group.

Conclusions

Improvement of medical management during chemotherapy and the development of several regimens for salvage chemotherapy seemed to contribute to improving outcomes of patients with advanced testicular cancer. Newly established chemotherapy regimens are needed for improvement of survival of patients in the poor-prognosis group.

  K Hashimoto , S. i Hisasue , N Masumori , K Kobayashi , R Kato , F Fukuta , A Takahashi , T Hasegawa and T. Tsukamoto
  Objective

We investigated the clinical safety and feasibility of an algorithm we developed for the decision-making on neurovascular bundle preservation in radical prostatectomy to decrease the incidence of positive surgical margins.

Methods

We prospectively applied our algorithm to 82 patients (164 prostate sides) with clinically localized prostate cancer who underwent radical prostatectomy at our institution between October 2004 and September 2006. The algorithm was developed using the apical core characteristics, clinical T stage, preoperative prostate-specific antigen level and Gleason sum. All prostate sides were divided into two groups by the algorithm: 115 sides (70.1%) were qualified for neurovascular bundle preservation (favorable algorithm side group) and 49 sides (29.9%) for non-neurovascular bundle preservation (unfavorable algorithm side group).

Results

Median patient age was 66 years (range: 52–77) and median prostate-specific antigen was 7.1 ng/ml (range: 1.4–29.6). Overall, a positive surgical margin was observed in 23 sides (14.0%). The incidence of positive surgical margins at the apex was significantly correlated with the maximal diameter of the tumor in the apex (P < 0.001). The incidence of positive surgical margins was 8.7% in the favorable algorithm group, whereas it was 26.5% in the unfavorable algorithm group (P = 0.003). When this algorithm was combined with surgeons' intraoperative assessments, the incidence of positive surgical margins was 2.1% in neurovascular bundle preservation sides, compared with 25.0% in non-neurovascular bundle preservation sides (P = 0.002).

Conclusions

This simple algorithm is safe and feasible for the decision-making on neurovascular bundle preservation from the aspect of cancer control in radical prostatectomy patients.

  H Uozumi , T Sugita , T Aizawa , A Takahashi , M Ohnuma and E. Itoi
  Background

The histologic findings of osteochondritis dissecans of the knee vary widely, leading to differences in the interpretation of its origins.

Hypothesis

The differences in the histologic findings of osteochondritis dissecans might represent a course of pathologic progression.

Study Design

Descriptive laboratory study.

Methods

Twelve knees in 11 patients (average age, 16 years) with osteochondritis dissecans of the medial femoral condyle were treated by biological internal fixation. During the surgery, cylinder osteochondral plugs were taken from the center of the osteochondritis dissecans lesion and examined with light microscopy.

Results

A complete or partial cleft separated the specimens into 2 parts: basal and fragment sides. The surface of the basal side was covered with dense fibrous or cartilaginous tissue and active bone remodeling was found beneath the surface. In the fragment side, the deep surface was also covered with dense fibrous or cartilaginous tissue and the articular surface consisted of normal articular cartilage. The area between these 2 surfaces could be classified into 3 types: (1) necrotic subchondral trabeculae, (2) viable subchondral trabeculae, and (3) cartilage without bone trabeculae.

Conclusion

Based on the histologic findings of this study, the following origins and the pathologic progression of osteochondritis dissecans might be assumed: the initial change in the subchondral area is bone necrosis or subchondral fracture; the necrotic bone is then absorbed and replaced either by viable subchondral trabeculae or cartilage without bone trabeculae.

Clinical Relevance

The results of this histologic study provide readers with several insights about the causes and treatment options of osteochondritis dissecans.

  K Yamakoshi , A Takahashi , F Hirota , R Nakayama , N Ishimaru , Y Kubo , D. J Mann , M Ohmura , A Hirao , H Saya , S Arase , Y Hayashi , K Nakao , M Matsumoto , N Ohtani and E. Hara
 

Expression of the p16Ink4a tumor suppressor gene, a sensor of oncogenic stress, is up-regulated by a variety of potentially oncogenic stimuli in cultured primary cells. However, because p16Ink4a expression is also induced by tissue culture stress, physiological mechanisms regulating p16Ink4a expression remain unclear. To eliminate any potential problems arising from tissue culture–imposed stress, we used bioluminescence imaging for noninvasive and real-time analysis of p16Ink4a expression under various physiological conditions in living mice. In this study, we show that oncogenic insults such as ras activation provoke epigenetic derepression of p16Ink4a expression through reduction of DNMT1 (DNA methyl transferase 1) levels as a DNA damage response in vivo. This pathway is accelerated in the absence of p53, indicating that p53 normally holds the p16Ink4a response in check. These results unveil a backup tumor suppressor role for p16Ink4a in the event of p53 inactivation, expanding our understanding of how p16Ink4a expression is regulated in vivo.

 
 
 
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