Characterizing scale dependence of effective diffusion driven by fluid flows

We study the scale dependence of effective diffusion of fluid tracers, specifically, its dependence on the P\'{e}clet number, a dimensionless parameter of the ratio between advection and molecular diffusion. Here, we address the case that length and time scales on which the effective diffusion can be described are not separated from those of advection and molecular diffusion. For this, we propose a new method for characterizing the effective diffusivity without relying on the scale separation. For a given spatial domain inside which the effective diffusion can emerge, a time constant related to the diffusion is identified by considering the spatio-temporal evolution of a test advection-diffusion equation, where its initial condition is set at a pulse function. Then, the value of effective diffusivity is identified by minimizing the $L_\infty$ distance between solutions of the above test equation and the diffusion one with mean drift. With this method, for time-independent gyre and time-periodic shear flows, we numerically show that the scale dependence of the effective diffusivity changes beyond the conventional theoretical regime. Their kinematic origins are revealed as the development of the molecular diffusion across flow cells of the gyre and as the suppression of the drift motion due to a temporal oscillation in the shear.Comment: 10 pages, 4 figure

Effects of Perioperative Management Training Program on the Awareness of Team Medicine among Trainee Dentists

　質が高く、安心・安全な医療を実現していくために、チーム医療の促進は重要な課題であり、チーム医療を担う医療人の育成が必要とされている。岡山大学病院歯科医師臨床研修では、平成23年度から周術期管理センターを研修の場とする「チーム医療研修プログラム」を開始した。本報告では、研修歯科医のプログラムに対する関心とチーム医療に関する理解に与えた効果をアンケート調査によって検討することを目的とした。対象は平成23年度本学病院研修歯科医44名とし、医師、看護師、薬剤師、理学療法士、管理栄養士など多職種によって行われる周術期管理チーム医療を体験させた。受講前には本プログラムに対する期待度を、受講後には満足度、有意義度について質問し、研修歯科医のプログラムに対する関心度を評価した。また、プログラム受講前後に周術期チーム医療に関する用語や職種について質問し、チーム医療に関する理解度を評価した。90.9%の研修歯科医がプログラムに対して期待し、受講後は88.6%が満足だった、84.1%が有意義だったと回答した。さらに、周術期管理に関する用語について主観的理解度が向上し、チーム医療にかかわる職種についての理解が深まった。歯科医師臨床研修におけるチーム医療教育の方法として、周術期管理チーム医療の現場に実際に関与させるプログラムは、研修歯科医の関心が高く、研修歯科医の周術期管理チーム医療に対する理解を深めることが示唆された

Daikenchuto accelerates the recovery from prolonged postoperative ileus after open abdominal surgery : a subgroup analysis of three randomized controlled trials

Purpose Prolonged postoperative ileus (POI) is a common complication after open abdominal surgery (OAS). Daikenchuto (DKT), a traditional Japanese medicine that peripherally stimulates the neurogenic pathway, is used to treat prolonged POI in Japan. To analyze whether DKT accelerates the recovery from prolonged POI after OAS, we conducted a secondary analysis of three multicenter randomized controlled trials (RCTs). Methods A secondary analysis of the three RCTs supported by the Japanese Foundation for Multidisciplinary Treatment of Cancer (project numbers 39-0902, 40-1001, 42-1002) assessing the effect of DKT on prolonged POI in patients who had undergone OAS for colon, liver, or gastric cancer was performed. The subgroup included 410 patients with no bowel movement (BM) before the first diet, a DKT group (n = 214), and a placebo group (n = 196). Patients received either 5 g DKT or a placebo orally, three times a day. The primary endpoint was defined as the time from the end of surgery to the first bowel movement (FBM). A sensitivity analysis was also performed on the age, body mass index and dosage as subgroup analyses. Results The primary endpoint was significantly accelerated in the DKT group compared with the placebo group (p = 0.004; hazard ratio 1.337). The median time to the FBM was 113.8 h in the placebo group and 99.1 h in the DKT treatment group. Conclusions The subgroup analysis showed that DKT significantly accelerated the recovery from prolonged POI following OAS

Cigarette smoking, genetic polymorphisms and colorectal cancer risk: the Fukuoka Colorectal Cancer Study

Background: It is uncertain whether smoking is related to colorectal cancer risk. Cytochrome P-450 CYP1A1, glutathione-S-transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1) are important enzymes in the metabolism of tobacco carcinogens, and functional genetic polymorphisms are known for these enzymes. We investigated the relation of cigarette smoking and related genetic polymorphisms to colorectal cancer risk, with special reference to the interaction between smoking and genetic polymorphism. Methods: We used data from the Fukuoka Colorectal Cancer Study, a population-based case-control study, including 685 cases and 778 controls who gave informed consent to genetic analysis. Interview was conducted to assess lifestyle factors, and DNA was extracted from buffy coat. Results: In comparison with lifelong nonsmokers, the odds ratios (OR) of colorectal cancer for <400, 400-799 and ≥800 cigarette-years were 0.65 (95 % confidence interval [CI], 0.45-0.89), 1.16 (0.83-1.62) and 1.14 (0.73-1.77), respectively. A decreased risk associated with light smoking was observed only for colon cancer, and rectal cancer showed an increased risk among those with ≥400 cigarette-years (OR 1.60, 95 % CI 1.04-2.45). None of the polymorphisms under study was singly associated with colorectal cancer risk. Of the gene-gene interactions studied, the composite genotype of CYP1A1*2A or CYP1A1*2C and GSTT1 polymorphisms was associated with a decreased risk of colorecta

課題別各研究の紹介

調査研究から情報発信へ─4年目を迎え大幅な組織改編─It Is Time for Us to Present Our Results at Larg

Biological mechanism and clinical effect of protein-bound polysaccharide K (KRESTIN®): review of development and future perspectives

The mechanism of action of protein-bound polysaccharide K (PSK; KRESTIN®) involves the following actions: (1) recovery from immunosuppression induced by humoral factors such as transforming growth factor (TGF)-β or as a result of surgery and chemotherapy; (2) activation of antitumor immune responses including maturation of dendritic cells, correction of Th1/Th2 imbalance, and promotion of interleukin-15 production by monocytes; and (3) enhancement of the antitumor effect of chemotherapy by induction of apoptosis and inhibition of metastasis through direct actions on tumor cells. The clinical effectiveness of PSK has been demonstrated for various cancers. In patients with gastric or colorectal cancer, combined use of PSK with postoperative adjuvant chemotherapy prolongs survival, and this effect has been confirmed in multiple meta-analyses. For small-cell lung carcinoma, PSK in conjunction with chemotherapy prolongs the remission period. In addition, PSK has been shown to be effective against various other cancers, reduce the adverse effects of chemotherapy, and improve quality of life. Future studies should examine the effects of PSK under different host immune conditions and tumor properties, elucidate the mechanism of action exhibited in each situation, and identify biomarkers