Growth responses of Escherichia coli and Myxococcus xanthus on agar gel substrates with different levels of stiffness

Bacteria colonize surfaces responding to the physicochemical properties of substrates. A systematic study was carried out with growing single bacterial colonies on the surface of agar media to decipher the interaction between bacterial growth and substrate stiffness. We investigated the growth kinetics of wild-type Escherichia coli, non-motile E. coli, and Myxococcus xanthus, cultured on semi-solid agar substrates containing different amounts of nutrient and agar. We found that substrate stiffness, which was controlled by agar concentration, modulates the growth of motile bacteria, such as wild-type E. coli and M. xanthus, independently of the nutrient level, but does not affect the growth response of non-motile E. coli. Interestingly, growth of M. xanthus moving with type IV pili correlates negatively with the substrate stiffness in contrast to wild-type E. coli propelled by flagella. The present study demonstrates that the type of surface motility is a key  determinant of the growth response of bacteria to substrate stiffness, and has potential application to the design of surfaces that prevent or promote biofilm formation.Key words: Bacterial colonization, substrate stiffness, surface motility, swarming, Escherichia coli, Myxococcus xanthus

A Self-Propelled Biological Process Plk1-Dependent Product-Activated, Feed-Forward Mechanism

Comment on: Park JE, et al. Proc Natl Acad Sci USA 2011; 108:8200-05.Molecular and Cellular Biolog

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Improving disclosure of medical error through educational program as a first step toward patient safety

Participant’s Response to medical errors. Description of data: Raw data of participant’s response to medical errors (3 clinical cases with different severity of error outcome), satisfaction and change after the education program. (XLSX 18 kb

The Prognostic Implications of Cystic Change in Clear Cell Renal Cell Carcinoma

Background : Cystic renal cell carcinoma has been reported to have a good prognosis. However, previous studies included cases of multilocular cystic renal cell carcinoma, which has an excellent prognosis, and renal cell carcinoma with cystic necrosis, which has an adverse prognosis. Therefore, we analyzed the prognostic influence of cystic change in clear cell renal cell carcinoma after excluding those morphological features. Methods : We identified 225 patients with clear cell renal cell carcinoma who underwent nephrectomy between 2001 and 2003. The clinicopathologic features were compared with clinical outcomes. Results : Cystic change in clear cell renal cell carcinoma (n = 66) was significantly associated with younger patient age (< 55), smaller tumor size (<= 4 cm), lower pT stage (pT1, T2), M0 stage at initial diagnosis, lower tumor, node, and metastasis stage (I, II), and lower nuclear grade (1, 2). Patients with cystic change in clear cell renal cell carcinoma had significantly longer cancer-specific (p = 0.015) and progression-free survival (p = 0.004) than those without cystic change, by univariate analysis. Multivariate analysis revealed that cystic change significantly decreased the risk of cancer progression (risk ratio, 0.27; 95% confidence interval, 0.11 to 0.69). Conclusions : In patients with clear cell renal cell carcinoma, cystic change is a good independent predictor for survival.This work was supported by grant No. 04-2009-007 from the SNUH Research Fund.Jemal A, 2009, CA-CANCER J CLIN, V59, P225, DOI 10.3322/caac.20006Lopez-Beltran A, 2009, INT J UROL, V16, P432, DOI 10.1111/j.1442-2042.2009.02302.xGobbo S, 2008, AM J SURG PATHOL, V32, P1239Gong K, 2008, J CANCER RES CLIN, V134, P433, DOI 10.1007/s00432-007-0302-1Webster WS, 2007, UROLOGY, V70, P900, DOI 10.1016/j.urology.2007.05.029Lopez-Beltran A, 2006, EUR UROL, V49, P798, DOI 10.1016/j.eururo.2005.11.035Suzigan S, 2006, AM J CLIN PATHOL, V125, P217, DOI 10.1039/AH6FC77PYR2V6YAYFrank I, 2005, J UROLOGY, V173, P1889, DOI 10.1097/01.ju.0000158043.94525.d6Patard JJ, 2005, J CLIN ONCOL, V23, P2763, DOI 10.1200/JCO.2005.07.055Kim H, 2004, HUM PATHOL, V35, P1556, DOI 10.1016/j.humpath.2004.06.011Ficarra V, 2004, EUR UROL, V46, P559, DOI 10.1016/j.eururo.2004.07.002Han KR, 2004, UROL ONCOL-SEMIN ORI, V22, P410, DOI 10.1016/S1078-1439(03)00173-XImura J, 2004, APMIS, V112, P183Cheville JC, 2003, AM J SURG PATHOL, V27, P612Frank I, 2002, J UROLOGY, V168, P2395, DOI 10.1097/01.ju.0000035885.91935.d5Nassir A, 2002, UROLOGY, V60, P421GREENE FL, 2002, AJCC CANC STAGING MACorica FA, 1999, J UROLOGY, V161, P408Bielsa O, 1998, BRIT J UROL, V82, P16USUBUTUN A, 1998, INT UROL NEPHROL, V30, P391LYNCH CF, 1995, CANCER, V75, P316HARTMAN DS, 1986, UROLOGY, V28, P145

Benign Aspirates on Follow-Up FNA May Be Enough in Patients with Initial Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance

Background. Management of thyroid nodules with benign aspirates following atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is not well established. We reviewed the risk of malignancy and the role of ultrasound (US) features among thyroid nodules with benign results following initial AUS/FLUS diagnoses. Methods. From December 2009 to February 2011, a total of 114 nodules in 114 patients diagnosed as benign on follow-up fine-needle aspiration (FNA) after AUS/FLUS results were included in our study. Eight among 114 nodules were confirmed pathologically and 106 were clinically observed by a follow-up FNA or US. Suspicious US features were defined as markedly hypoechogenicity, irregular or microlobulated margin, presence of microcalcifications, and taller than wide shape. Results. There were 110 (96.5%) benign nodules and 4 (3.5%) malignant nodules. Two (4.8%) among 42 nodules without suspicious US features and 2 (2.8%) out of 72 nodules with suspicious US features were confirmed as malignancy, but there were no significant associations between the malignancy rate and US features (P=0.625). Conclusion. Clinical follow-up instead of surgical excision or continuous repeat FNA may be enough for benign thyroid nodules after AUS/FLUS. The role of US features might be insignificant in the management of these nodules

Self-regulated mechanism of Plk1 localization to kinetochores: lessons from the Plk1-PBIP1 interaction

Mammalian polo-like kinase 1 (Plk1) has been studied extensively as a critical element in regulating various mitotic events during M-phase progression. Plk1 function is spatially regulated through the targeting activity of the conserved polo-box domain (PBD) present in the C-terminal non-catalytic region. Recent progress in our understanding of Plk1 localization to the centromeres shows that Plk1 self-regulates its initial recruitment by phosphorylating a centromeric component PBIP1 and generating its own PBD-binding site. Paradoxically, Plk1 also induces PBIP1 delocalization and degradation from the mitotic kinetochores late in the cell cycle, consequently permitting itself to bind to other kinetochore components. Thus, PBIP1-dependent self-recruitment of Plk1 to the interphase centromeres serves as a prelude to the efficient delivery of Plk1 itself to other kinetochore components whose interactions with Plk1 are vital for proper mitotic progression

Delta neutrophil index as a predictor of vesicoureteral reflux in children with febrile urinary tract infection

Purpose Delta neutrophil index (DNI) indicates immature granulocytes in peripheral blood and has been confirmed to be effective as a prognostic factor for neonatal sepsis. Also, it has been reported to have diagnostic value in acute pyelonephritis and in predicting vesicoureteral reflux (VUR) in the infant. We conducted the study to verify whether DNI is also helpful in the entire pediatric age group with febrile urinary tract infection (UTI). Methods Medical records of children hospitalized for febrile UTIs were analyzed retrospectively. All subjects underwent kidney ultrasound and voiding cystourethrography. In the group with and without VUR, we compared sex and age, and the following laboratory values: the white blood cell count, neutrophil, polymorphonuclear leucocyte, eosinophil, hemoglobin, platelet count, C-reactive protein, DNI value, and the finding of ultrasound. Results A total of 315 patients (163 males and 152 females; range, 0–127 months) were eligible, and 41 patients (13%) had VUR. As a result of univariate analysis, the white blood cell count, neutrophil, DNI, and ultrasonic abnormalities were high in the reflux group, and the hemoglobin and lymphocyte fraction values were low. The value of DNI and the abnormal ultrasound were significantly higher in the reflux group on the multivariate analysis. The area under the curve value of the receiver operating curve was higher in DNI (0.640; 95% confidence interval, 0.536–0.744; P=0.004), and the DNI cutoff value for VUR prediction was 1.85%. Conclusions We identified that ultrasound findings and DNI values were helpful predictors of VUR in pediatric febrile UTIs