1,797 research outputs found

    Regulation of Growth in Avena Stem Segments by Gibberellic Acid and Kinetin

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    Kinetin at physiological concentrations causes significant reduction of GA 3 -promoted growth in excised Avena stem segments. Kinetin is therefore considered to be a gibberellin-antagonist in this system. A Lineweaver-Burke plot reveals that kinetin acts non-competitively with GA 3 . The kinetin inhibition of GA 3 -promoted growth can be seen within 6 hours. It was found that soluble protein is markedly increased by kinetin in the tissue during the first 3 hours, thus preceding the inhibition of GA 3 -promoted growth by several hours. At the cellular level, kinetin negated the blocking effect of GA 3 on cell division in the intercalary meristem portions of these segments. In fact, kinetin promotes both lateral and longitudinal cell divisions in intercalary meristem cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73968/1/j.1399-3054.1971.tb03524.x.pd

    Racial disparities in treatment patterns and clinical outcomes in patients with HER2-positive metastatic breast cancer.

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    Data characterizing demographics, treatment patterns, and clinical outcomes in black patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) are limited. registHER is a large, observational cohort study of patients (n = 1,001) with HER2-positive MBC diagnosed ≤6 months of enrollment and followed until death, disenrollment, or June 2009 (median follow-up of 27 months). Demographics, treatment patterns, and clinical outcomes were described for black (n = 126) and white patients (n = 793). Progression-free survival (PFS) following first-line therapy and overall survival (OS) were examined. Multivariate analyses adjusted for baseline and treatment factors. Black patients were more likely than white patients to be obese (body mass index ≥30), to have diabetes, and to have a history of cardiovascular disease; they were also less likely to have estrogen receptor or progesterone receptor positive disease. In patients treated with trastuzumab, the incidence of cardiac safety events (grade ≥3) was higher in black patients (10.9 %) than in white patients (7.9 %). Unadjusted median OS and PFS (months) were significantly lower in black patients than in white patients (OS: black: 27.1, 95 % confidence interval [CI] 21.3-32.1; white: 37.3, 95 % CI 34.6-41.1; PFS: black: 7.0, 95 % CI 5.7-8.2; white: 10.2, 95 % CI 9.3-11.2). The adjusted OS hazard ratio (HR) for black patients compared with white patients was 1.29 (95 % CI 1.00-1.65); adjusted PFS HR was 1.29 (95 % CI 1.05-1.59). This real-world evaluation of a large cohort of patients with HER2-positive MBC shows poorer prognostic factors and independently worse clinical outcomes in black versus white patients. Further research is needed to identify potential biologic differences that could have predictive impact for black patients or that could explain these differences

    Role of lateral cell–cell border location and extracellular/transmembrane domains in PECAM/CD31 mechanosensation

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    Phosphorylation of tyrosine residues on platelet–endothelial cell adhesion molecule-1 (PECAM-1), followed by signal trans- 13 duction events, has been described in endothelial cells following exposure to hyperosmotic and fluid shear stress. However, it is 14 unclear whether PECAM-1 functions as a primary mechanosensor in this process. Utilizing a PECAM-1–null EC-like cell line, we 15 examined the importance of cellular localization and the extracellular and transmembrane domains in PECAM-1 phosphorylation 16 responses to mechanical stress. Tyrosine phosphorylation of PECAM-1 was stimulated in response to mechanical stress in null cells 17 transfected either with full length PECAM-1 or with PECAM-1 mutants that do not localize to the lateral cell–cell adhesion site and 18 that do not support homophilic binding between PECAM-1 molecules. Furthermore, null cells transfected with a construct that 19 contains the intact cytoplasmic domain of PECAM-1 fused to the extracellular and transmembrane domains of the interleukin-2 20 receptor also underwent mechanical stress-induced PECAM-1 tyrosine phosphorylation. These findings suggest that mechano- 21 sensitive PECAM-1 may lie downstream of a primary mechanosensor that activates a tyrosine kinase

    Treatment patterns and clinical outcomes in elderly patients with HER2-positive metastatic breast cancer from the registHER observational study.

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    Limited data exist regarding treatment patterns and outcomes in elderly patients with HER2-positive metastatic breast cancer (MBC). registHER is an observational study of patients (N = 1,001) with HER2-positive MBC diagnosed within 6 months of enrollment and followed until death, disenrollment, or June 2009 (median follow-up 27 months). Outcomes were analyzed by age at MBC diagnosis: younger (<65 years), older (65-74 years), elderly (≥75 years). For progression-free survival (PFS) and overall survival (OS) analyses of first-line trastuzumab versus nontrastuzumab, older and elderly patients were combined. Cox regression analyses were adjusted for baseline characteristics and treatments. Estrogen receptor/progesterone receptor status was similar across age groups. Underlying cardiovascular disease was most common in elderly patients. In patients receiving trastuzumab-based first-line treatment, elderly patients were less likely to receive chemotherapy. In trastuzumab-treated patients, incidence of left ventricular dysfunction (LVD) and congestive heart failure (CHF) (grades ≥ 3) were highest in elderly patients (LVD: elderly 4.8 %, younger 2.8 %, older 1.5 %; CHF: elderly 3.2 %, younger 1.9 %, older 1.5 %). Unadjusted median PFS (months) was significantly higher in patients treated with first-line trastuzumab than those who were not (<65 years: 11.0 vs. 3.4, respectively; ≥65 years: 11.7 vs. 4.8, respectively). In patients <65 years, unadjusted median OS (months) was significantly higher in trastuzumab-treated patients; in patients ≥65 years, median OS was similar (<65 years: 40.4 vs. 25.9; ≥65 years: 31.2 vs. 28.5). In multivariate analyses, first-line trastuzumab use was associated with significant improvement in PFS across age. For OS, significant improvement was observed for patients <65 years and nonsignificant improvement for patients ≥65 years. Elderly patients with HER2-positive MBC had higher rates of underlying cardiovascular disease than their younger counterparts and received less aggressive treatment, including less first-line trastuzumab. These real-world data suggest improved PFS across all age groups and similar trends for OS

    Upregulation of Isoflavonoids and Soluble Proteins in Edible Legumes by Light and Fungal Elicitor Treatments

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    Objective: In this study, our working hypothesis was that continuous light and fungal elicitation treatment of legume seedlings would lead to enhanced levels of isoflavonoids and soluble proteins. Results: Based on short-term light and dark treatments, isoflavonoid (genistein, genistin, daidzein, and daidzin) and soluble protein concentrations were significantly upregulated in the "light" environment compared to the "dark" environment for all edible legume species (kudzu vine, soybean, garbanzo bean, fava bean, mung bean, adzuki bean) that were tested. Kudzu seedlings showed the highest levels of both isoflavonoids and soluble proteins after light-elicited upregulation compared to the other legumes analyzed. All legumes showed less up-regulation of isoflavonoid synthesis when treated with Phytophtora sojae fungal elicitor. Oligosaccharide fungal elicitor caused no such upregulation. Conclusions: The findings in this study show that edible legume seedlings have enhanced levels of isoflavonoids and soluble proteins when they are grown in the light compared to the conventional practice of growing such seedlings in the dark. This will clearly result in significant improvement in their nutritive and medicinal value.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63222/1/107555303765551598.pd

    On Resolution of the Selectivity/Conductivity Paradox for the Potassium Ion Channel

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    The ability of the potassium channel to conduct K+ at almost the rate of free diffusion, while discriminating strongly against the (smaller) Na+ ion, is of enormous biological importance [1]. Yet its function remains at the center of a “many-voiced debate” [2,3]. In this presentation, a first-principles explanation is provided for the seemingly paradoxical coexistence of high conductivity with high selectivity between monovalent ions within the channel. It is shown that the conductivity of the selectivity filter is described by the generalized Einstein relation. A novel analytic approach to the analysis of the conductivity is proposed, based on the derivation of an effective grand canonical ensemble for ions within the filter. The conditions for barrier-less diffusion-limited conduction through the KcsA filter are introduced, and the relationships between system parameters required to satisfy these conditions are derived. It is shown that the Eisenman selectivity equation is one of these, and that it follows directly from the condition for barrier-less conduction. The proposed theory provides analytical insight into the “knock-on” [1] and Coulomb blockade [4] mechanisms of K+ conduction through the KcsA filter. It confirms and illuminates an earlier argument [3] that the “snug-fit" model cannot describe the fast diffusion-limited conduction seen in experiments. Numerical examples are provided illustrating agreement of the theory with experimentally-measured I-V curves. The results are not restricted to biological systems, but also carry implications for the design of artificial nanopores
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