检索结果-南通市图书馆

Open Journal of Statistics 2016年第5期6卷 766-776页

作者： yasutaka chiba Clinical Research Center Kinki University Hospital Osaka Japan

The main purpose in many randomized trials is to make an inference about the average causal effect of a treatment. Therefore, on a binary outcome, the null hypothesis for the hypothesis test should be that the causal risks are equal in the two groups. This null hypothesis is referred to as the weak causal null hypothesis. Nevertheless, at present, hypothesis tests applied in actual randomized trials are not for this null hypothesis;Fisher’s exact test is a test for the sharp causal null hypothesis that the causal effect of treatment is the same for all subjects. In general, the rejection of the sharp causal null hypothesis does not mean that the weak causal null hypothesis is rejected. Recently, chiba developed new exact tests for the weak causal null hypothesis: a conditional exact test, which requires that a marginal total is fixed, and an unconditional exact test, which does not require that a marginal total is fixed and depends rather on the ratio of random assignment. To apply these exact tests in actual randomized trials, it is inevitable that the sample size calculation must be performed during the study design. In this paper, we present a sample size calculation procedure for these exact tests. Given the sample size, the procedure can derive the exact test power, because it examines all the patterns that can be obtained as observed data under the alternative hypothesis without large sample theories and any assumptions.

关键词： Causal Inference Conditional and Unconditional Exact Test Potential Outcome Two-by-Two Contingency Table

A Simple Method of Measuring Vaccine Effects on Infectiousness and Contagion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Statistics 2013年第4期3卷 7-15页

作者： yasutaka chiba Division of Biostatistics Clinical Research Center Kinki University School of Medicine Osaka Japan

The vaccination of one person may prevent another from becoming infected, either because the vaccine may prevent the first person from acquiring the infection and thereby reduce the probability of transmission to the second, or because, if the first person is infected, the vaccine may impair the ability of the infectious agent to initiate new infections. The former mechanism is referred as a contagion effect and the latter is referred as an infectiousness effect. By applying a principal stratification approach, the conditional infectiousness effect has been defined, but the contagion effect is not defined using this approach. Recently, new definitions of unconditional infectiousness and contagion effects were provided by applying a mediation analysis approach. In addition, a simple relationship between conditional and unconditional infectiousness effects was found under a number of assumptions. These two infectiousness effects can be assessed by very simple estimation and sensitivity analysis methods under the assumptions. Nevertheless, such simple methods to assess the contagion effect have not been discussed. In this paper, we review the methods of assessing infectiousness effects, and apply them to the inference of the contagion effect. The methods provided here are illustrated with hypothetical vaccine trial data.

关键词： Indirect Effect Interference Mediation Analysis Potential Outcome Principal Stratification

Causal Measures for Prognostic and Predictive Biomarkers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Statistics 2018年第2期8卷 241-248页

作者： yasutaka chiba Clinical Research Center Kinki University Hospital Osaka Japan

Researchers conducting randomized clinical trials with two treatment groups sometimes wish to determine whether biomarkers are predictive and/or prognostic. They can use regression models with interaction terms to assess the role of the biomarker of interest. However, although the interaction term is undoubtedly a suitable measure for prediction, the optimal way to measure prognosis is less clear. In this article, we define causal measures that can be used for prognosis and prediction based on biomarkers. The causal measure for prognosis is defined as the average of two differences in status between biomarker-positive and -negative subjects under treatment and control conditions. The causal measure for prediction is defined as the difference between the causal effect of the treatment for biomarker-positive and biomarker-negative subjects. We also explain the relationship between the proposed measures and the regression parameters. The causal measure for prognosis corresponds to the terms for the biomarker in a regression model, where the values of the dummy variables representing the explanatory variables are -1/2 or 1/2. The causal measure for prediction is simply the causal effect of the interaction term in a regression model. In addition, for a binary outcome, we express the causal measures in terms of four response types: always-responder, complier, non-complier, and never-responder. The causal measure for prognosis can be expressed as a function of always- and never-responders, and the causal measure for prediction as a function of compliers and non-compliers. This enables us to demonstrate that the proposed measures are plausible in the case of a binary outcome. Our causal measures should be used to assess whether a biomarker is prognostic and/or predictive.

关键词： Causal Inference Interaction Potential Outcome Response Type

Clinical utility of treatment method conversion during single-session endoscopic ultrasound-guided biliary drainage

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2020年第9期26卷 947-959页

作者： Kosuke Minaga Mamoru Takenaka Kentaro Yamao Ken Kamata Shunsuke Omoto Atsushi Nakai Tomohiro Yamazaki Ayana Okamoto Rei Ishikawa Tomoe Yoshikawa yasutaka chiba Tomohiro Watanabe Masatoshi Kudo Department of Gastroenterology and Hepatology Kindai University Faculty of MedicineOsaka-Sayama 589-8511Japan Clinical Research Center Kindai University HospitalOsaka-Sayama 589-8511Japan

BACKGROUND Although several techniques for endoscopic ultrasound-guided biliary drainage(EUS-BD)are available at present,an optimal treatment algorithm of EUS-BD has not yet been *** To evaluate the clinical utility of treatment method conversion during single endoscopic sessions for difficult cases in initially planned *** This was a single-center retrospective analysis using a prospectively accumulated *** with biliary obstruction undergoing EUS-BD between May 2008 and April 2016 were *** primary outcome was to evaluate the improvement in EUS-BD success rates by converting the treatment methods during a single endoscopic *** outcomes were clarification of the factors leading to the conversion from the initial EUS-BD and the assessment of efficacy and safety of the conversion as judged by technical success,clinical success,and adverse events(AEs).RESULTS A total of 208 patients underwent EUS-BD during the study *** 18.8%(39/208)of the patients,the treatment methods were converted to another EUSBD technique from the initial *** obstruction was caused by pancreatobiliary malignancies,other malignant lesions,biliary stones,and other benign lesions in 22,11,4,and 2 patients,*** reasons for the difficulty with the initial EUS-BD were classified into the following 3 procedures:Target puncture(n=13),guidewire manipulation(n=18),and puncture tract dilation(n=8).Technical success was achieved in 97.4%(38/39)of the cases and clinical success was achieved in 89.5%of patients(34/38).AEs occurred in 10.3%of patients,including bile leakage(n=2),bleeding(n=1),and cholecystitis(n=1).The puncture target and drainage technique were altered in subsequent EUSBD procedures in 25 and 14 patients,*** final technical success rate with 95%CI for all 208 cases was 97.1%(95%CI:93.8%-98.9%),while that of the initially planned EUS-BD was 78.8%(95%CI:72.6%-84.2%).CONCLUSION Among multi-step pro

关键词： Endoscopic ultrasound Endoscopic ultrasound-guided biliary drainage Interventional endoscopic ultrasound Biliary drainage Biliary obstruction

Contrast-enhanced harmonic endoscopic ultrasonography for assessment of lymph node metastases in pancreatobiliary carcinoma

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2016年第12期22卷 3381-3391页

作者： Takeshi Miyata Masayuki Kitano Shunsuke Omoto Kumpei Kadosaka Ken Kamata Hajime Imai Hiroki Sakamoto Naoshi Nisida Yogesh Harwani Takamichi Murakami Yoshifumi Takeyama yasutaka chiba Masatoshi Kudo Department of Gastroenterology and Hepatology Kinki University Faculty of Medicine Department of Radiology Kinki University Faculty of Medicine Department of Surgery Kinki University Faculty of Medicine Division of Biostatistics Clinical Research Center Kinki University Faculty of Medicine

AIM: To assess the usefulness of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) for lymph node metastasis in pancreatobiliary ***: All patients suspected of pancreatobiliary carcinoma with visible lymph nodes after standard EUS between June, 2009 and January, 2012 were enrolled. In the primary analysis, patients with successful EUS-fine needle aspiration (FNA) were included. The lymph nodes were assessed by several standard EUS variables (short and long axis lengths, shape, edge characteristic and echogenicity), color Doppler EUS variable [central intranodal blood vessel (CIV) presence] and CH-EUS variable (heterogeneous/homogeneous enhancement patterns). The diagnostic accuracy relative to EUS-FNA was calculated. In the second analysis, N-stage diagnostic accuracy of CH-EUS was compared with EUS-FNA in patients who underwent surgical ***: One hundred and nine patients (143 lymph nodes) fulfilled the criteria. The short axis cut-off ≥ 13 mm predicted malignancy with a sensitivity and specificity of 72% and 85%, respectively. These values were 72% and 63% for the long axis cut-off ≥ 20 mm, 62% and 75% for the round shape variable, 81% and 30% for the sharp edge variable, 66% and 61% for the hypoechogenicity variable, 70% and 72% for the CIV-absent variable, and 83% and 91% for the heterogeneous CH-EUS-enhancement variable, respectively. CH-EUS was more accurate than standard and color Doppler EUS, except the short axis cut-off. Notably, three patients excluded because of EUS-FNA failure were correctly N-staged by ***: CH-EUS complements standard and color Doppler EUS and EUS-FNA for assessment of lymph node metastases.

关键词： Contrast-enhanced harmonic endoscopic ultrasonography Sensitivity and specificity Lymph node Pancreatobiliary carcinoma Endoscopic ultrasonography-fine needle aspiration

Removal of diminutive colorectal polyps: A prospective randomized clinical trial between cold snare polypectomy and hot forceps biopsy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2017年第2期23卷 328-335页

作者： Yoriaki Komeda Hiroshi Kashida Toshiharu Sakurai George Tribonias Kazuki Okamoto Masashi Kono Mitsunari Yamada Teppei Adachi Hiromasa Mine Tomoyuki Nagai Yutaka Asakuma Satoru Hagiwara Shigenaga Matsui Tomohiro Watanabe Masayuki Kitano Takaaki Chikugo yasutaka chiba Masatoshi Kudo Department of Gastroenterology and Hepatology Kindai University Faculty of Medicine Department of Pathology Kindai University Faculty of Medicine Clinical Research Center Kindai University Hospital

AIMTo compare the efficacy and safety of cold snare polypectomy (CSP) and hot forceps biopsy (HFB) for diminutive colorectal *** prospective, randomized single-center clinical trial included consecutive patients ≥ 20 years of age with diminutive colorectal polyps 3-5 mm from December 2014 to October 2015. The primary outcome measures were en-bloc resection (endoscopic evaluation) and complete resection rates (pathological evaluation). The secondary outcome measures were the immediate bleeding or immediate perforation rate after polypectomy, delayed bleeding or delayed perforation rate after polypectomy, use of clipping for bleeding or perforation, and polyp retrieval rate. Prophylactic clipping after polyp removal wasn’t routinely *** hundred eight patients were randomized into the CSP (102), HFB (106) and 283 polyps were evaluated (CSP: 148, HFB: 135). The en-bloc resection rate was significantly higher with CSP than with HFB [99.3% (147/148) vs 80.0% (108/135), P < 0.0001]. The complete resection rate was significantly higher with CSP than with HFB [80.4% (119/148) vs 47.4% (64/135), P < 0.0001]. The immediate bleeding rate was similar between the groups [8.6% (13/148) vs 8.1% (11/135), P = 1.000], and endoscopic hemostasis with hemoclips was successful in all cases. No cases of perforation or delayed bleeding occurred. The rate of severe tissue injury to the pathological specimen was higher HFB than CSP [52.6% (71/135) vs 1.3% (2/148), P < 0.0001]. Polyp retrieval failure was encountered CSP (7), HFB (2).CONCLUSIONCSP is more effective than HFB for resecting diminutive polyps. Further long-term follow-up study is required.

关键词： Cold snare polypectomy Colonoscopy Polypectomy Colorectal diminutive polyps Hot forceps biopsy

Saturated hydraulic conductivity of compacted bentonite-sand mixtures before and after gas migration in artificial seawater

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 216-226页

作者： yasutaka Watanabe Shingo Yokoyama Misato Shimbashi Yoichi Yamamoto Takahiro Goto Sustainable System Research Laboratory Central Research Institute of Electric Power IndustryChibaJapan Science and Technology Department Nuclear Waste Management Organization of JapanTokyoJapan

To understand the self-healing property of an engineered barrier for radioactive waste disposal,the hydraulic conductivity of compacted bentoniteesand mixtures saturated with artificial seawater(SW)before and after gas migration was ***-and Ca-bentonites were mixed with fine sand at a ratio of 70%bentonite in dry *** aspects were considered during the experiment:the hydraulic conductivity of the specimen that was resaturated after gas migration and the distribution of water content immediately after gas migration to study gas migration *** gas migrated through the entire cross-section of the specimen,and gas breakthrough occurred in the equilibrium swelling pressure range ***,the gas flow rate reached a sufficient large value when the gas pressure was approximately twice the equilibrium axial pressure(the sum of swelling and confining pressures),which excluded the back *** the gas migration pathway was not visible when the specimen was observed immediately after gas migration,the water content distribution showed that several parts of the specimen with lower water content were connected in the direction of gas *** resaturation,the change in permeability was within a limited rangedtwo to three times larger than that before gas migration for each type of bentonite in *** slight change suggests that gas migration creates a pore structure that cannot be sealed via crystalline swelling of montmorillonite in SW,even if highly compacted bentonite is used under a constant-volume condition.

关键词： Bentonite Gas migration Hydraulic conductivity Seawater(SW) Self-healing

Treatment strategy for metastatic prostate cancer with extremely high PSA level： reconsidering the value of vintage therapy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2018年第5期20卷 432-437页

作者： yasutaka Yamada Shinichi Sakamoto Yoshiyasu Amiya Makoto Sasaki Takayuki Shima Akira Komiya Noriyuki Suzuki Koichiro Akakura Tomohiko Ichikawae Hiroomi Nakatsu Department of Urology Asahi General Hospital Asahi 289-2511 Japan Department of Urology Chiba University Graduate School of Medicine Chiba 260-8677 Japan Department of Urology Japan Community Healthcare Organization Tokyo Shinjuku Medical Center Tokyo 162-8543 Japan

The prognostic significance of initial prostate-specific antigen （PSA） level for metastatic prostate cancer remains uncertain. We investigated the differences in prognosis and response to hormonal therapies of metastatic prostate cancer patients according to initial PSA levels. We analyzed 184 patients diagnosed with metastatic prostate cancer and divided them into three PSA level groups as follows： low （〈100 ng ml-1）, intermediate （100–999 ng ml-1）, and high （≥1000 ng ml-1）. All patients received androgen deprivation therapy （ADT） immediately. We investigated PSA progression-free survival （PFS） for first-line ADT and overall survival （OS） within each of the three groups. Furthermore, we analyzed response to antiandrogen withdrawal （AW） and alternative antiandrogen （AA） therapies after development of castration-resistant prostate cancer （CRPC）. No significant differences in OS were observed among the three groups （P = 0.654）. Patients with high PSA levels had significantly short PFS for first-line ADT （P = 0.037）. Conversely, patients in the high PSA level group had significantly longer PFS when treated with AW than those in the low PSA level group （P = 0.047）. Furthermore, patients with high PSA levels had significantly longer PFS when provided with AA therapy （P = 0.049）. PSA responders to AW and AA therapies had significantly longer survival after CRPC development than nonresponders （P = 0.011 and P 〈 0.001, respectively）. Thus, extremely high PSA level predicted favorable response to vintage sequential ADT and AW. The current data suggest a novel aspect of extremely high PSA value as a favorable prognostic marker after development of CRPC.

关键词： alternative antiandrogen therapy antiandrogen withdrawal hormonal therapy metastatic prostate cancer prostate-specificantigen

Outcomes of patients older than 75 years with non-metastatic prostate cancer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Urology 2017年第2期4卷 102-106页

作者： Yoshiyasu Amiya yasutaka Yamada Masahiro Sugiura Makoto Sasaki Takayuki Shima Noriyuki Suzuki Hiroomi Nakatsu Shino Murakami Jun Shimazaki Department of Urology Asahi General HospitalAsahiJapan Department of Urology Graduate School of MedicineChiba UniversityChibaJapan

Objective:Prostate cancer in elderly patients was formerly treated with androgen deprivation *** the latter of the 1990s new technologies were introduced into treatments,then strategies have *** aimed to observe the outcomes of elderly patients treated during transition period and compare each stage with ***:During 2008 and 2010,255 patients with prostate cancer older than 75 years were sequentially *** exception of patients with bone and/or visceral metastasis,outcomes of 199 patients with localized and locally advanced stages were *** records were obtained by the end of ***:In total,122(61%),28(14%),37(19%)and 12(6%)of patients were in stages T1c-T2a,T2b-c,T3 and T4,*** generally presented with abnormal screening or lower urinary tract ***-one percent of patients received androgen deprivation therapy as monotherapy and 22% of the radiation-treated patients added androgen deprivation *** in stage T1c-T2a and T2b-c showed a favorable *** cancer death appeared in patients with T3 and T4 during observation ***-seven percent of patients died from prostate cancer-independent complications:pneumonia,heart disease,and brain vascular *** is similar to that of Japanese elderly male *** remarkable side effects from androgen deprivation therapy were noticed.

关键词： Prostate cancer Elderly Androgen deprivation Non-metastatic prostate cancer Radiation therapy

Short-Time Preparation of NaOH-Activated Carbon from Sugar Cane Bagasse Using Microwave Plasma Heating

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Green and Sustainable Chemistry 2017年第4期7卷 259-269页

作者： Katsuya Konno Yusuke Oike yasutaka Ohba Osamu Sasaki Yasuyuki Takiguchi Kaoru Onoe Tatsuaki Yamaguchi Department of Life and Environmental Sciences Faculty of Engineering Chiba Institute of Technology Chiba Japan (Present Address) Hitachi Automotive Systems Ltd. Advanced Development Centre Kawasaki Japan

The microwave induced argon plasma was applied to the preparation of NaOH-activated carbon from sugar cane bagasse. The distinguished feature of the heating technique with this cold plasma is the short operation time. The carbonization and the activation process were finalized in one step within 3 min. The prepared activated carbon with NaOH ratio 3 to bagasse characterized using N2 adsorption of type IV (IUPAC classification) to give specific surface area of 1980 m2/g and mesopore volume of 0.73 ml/g. It also showed a higher specific capacitance of 201 F/g in 1 M H2SO4 solution (with standard three electrodes) than the corresponding one by the conventional heating, previously reported. The other features were the absence of oxygen groups and the presence of carbon centered stable radicals, detected by ESR spectra, on the surface.

关键词： Bagasse Plasma Heating NaOH Activated Carbon EDLC Free Radical