21 research outputs found

    A Graphical Null Model for Scaling Biodiversity–Ecosystem Functioning Relationships

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    Global biodiversity is declining at rates faster than at any other point in human history. Experimental manipulations at small spatial scales have demonstrated that communities with fewer species consistently produce less biomass than higher diversity communities. Understanding the consequences of the global extinction crisis for ecosystem functioning requires understanding how local experimental results are likely to change with increasing spatial and temporal scales and from experiments to naturally assembled systems. Scaling across time and space in a changing world requires baseline predictions. Here, we provide a graphical null model for area scaling of biodiversity–ecosystem functioning relationships using observed macroecological patterns: the species–area curve and the biomass–area curve. We use species–area and biomass–area curves to predict how species richness–biomass relationships are likely to change with increasing sampling extent. We then validate these predictions with data from two naturally assembled ecosystems: a Minnesota savanna and a Panamanian tropical dry forest. Our graphical null model predicts that biodiversity–ecosystem functioning relationships are scale-dependent. However, we note two important caveats. First, our results indicate an apparent contradiction between predictions based on measurements in biodiversity–ecosystem functioning experiments and from scaling theory. When ecosystem functioning is measured as per unit area (e.g. biomass per m2), as is common in biodiversity–ecosystem functioning experiments, the slope of the biodiversity ecosystem functioning relationship should decrease with increasing scale. Alternatively, when ecosystem functioning is not measured per unit area (e.g. summed total biomass), as is common in scaling studies, the slope of the biodiversity–ecosystem functioning relationship should increase with increasing spatial scale. Second, the underlying macroecological patterns of biodiversity experiments are predictably different from some naturally assembled systems. These differences between the underlying patterns of experiments and naturally assembled systems may enable us to better understand when patterns from biodiversity–ecosystem functioning experiments will be valid in naturally assembled systems. Synthesis. This paper provides a simple graphical null model that can be extended to any relationship between biodiversity and any ecosystem functioning across space or time. Furthermore, these predictions provide crucial insights into how and when we may be able to extend results from small-scale biodiversity experiments to naturally assembled regional and global ecosystems where biodiversity is changing

    Impact of KRAS mutation status on the efficacy of immunotherapy in lung cancer brain metastases

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    Immune checkpoint inhibitors (ICIs) have resulted in improved outcomes in non-small cell lung cancer (NSCLC) patients. However, data demonstrating the efficacy of ICIs in NSCLC brain metastases (NSCLCBM) is limited. We analyzed overall survival (OS) in patients with NSCLCBM treated with ICIs within 90 days of NSCLCBM diagnosis (ICI-90) and compared them to patients who never received ICIs (no-ICI). We reviewed 800 patients with LCBM who were diagnosed between 2010 and 2019 at a major tertiary care institution, 97% of whom received stereotactic radiosurgery (SRS) for local treatment of BM. OS from BM was compared between the ICI-90 and no-ICI groups using the Log-Rank test and Cox proportional-hazards model. Additionally, the impact of KRAS mutational status on the efficacy of ICI was investigated. After accounting for known prognostic factors, ICI-90 in addition to SRS led to significantly improved OS compared to no-ICI (12.5 months vs 9.1, p \u3c 0.001). In the 109 patients who had both a known PD-L1 expression and KRAS status, 80.4% of patients with KRAS mutation had PD-L1 expression vs 61.9% in wild-type KRAS patients (p = 0.04). In patients without a KRAS mutation, there was no difference in OS between the ICI-90 vs no-ICI cohort with a one-year survival of 60.2% vs 54.8% (p = 0.84). However, in patients with a KRAS mutation, ICI-90 led to a one-year survival of 60.4% vs 34.1% (p = 0.004). Patients with NSCLCBM who received ICI-90 had improved OS compared to no-ICI patients. Additionally, this benefit appears to be observed primarily in patients with KRAS mutations that may drive the overall benefit, which should be taken into account in the development of future trials

    SerpinB3 Drives Cancer Stem Cell Survival in Glioblastoma

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    Despite therapeutic interventions for glioblastoma (GBM), cancer stem cells (CSCs) drive recurrence. The precise mechanisms underlying CSC resistance, namely inhibition of cell death, are unclear. We built on previous observations that the high cell surface expression of junctional adhesion molecule-A drives CSC maintenance and identified downstream signaling networks, including the cysteine protease inhibitor SerpinB3. Using genetic depletion approaches, we found that SerpinB3 is necessary for CSC maintenance, survival, and tumor growth, as well as CSC pathway activation. Knockdown of SerpinB3 also increased apoptosis and susceptibility to radiation therapy. SerpinB3 was essential to buffer cathepsin L-mediated cell death, which was enhanced with radiation. Finally, we found that SerpinB3 knockdown increased the efficacy of radiation in pre-clinical models. Taken together, our findings identify a GBM CSC-specific survival mechanism involving a cysteine protease inhibitor, SerpinB3, and provide a potential target to improve the efficacy of GBM therapies against therapeutically resistant CSCs

    Environmental catalysers of economic distress-induced self-harm

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    This thesis examines the relationship between the unemployment rates and suicide rates in Czech and Slovak districts from 2002 to 2020 by fixed effects model. The thesis found a positive link between the male suicide rate and the unemployment rate. For the female suicide rate, the link was insignificant. It was found that the moderating effect of built-up areas was estimated as negative, while the effect of population density was positive. These findings were only partially according to the literature, as we expected that both effects will be negative. The moderating effects of greenery and divorce rate were estimated as insignificant. However, the validity of these findings is questionable, as the goodness of fit measures are poor and were increased only after increasing the level of aggregation from NUTS4 to NUTS

    Environmentální faktory sebepoškozování způsobené ekonomickou tísní

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    This thesis examines the relationship between the unemployment rates and suicide rates in Czech and Slovak districts from 2002 to 2020 by fixed effects model. The thesis found a positive link between the male suicide rate and the unemployment rate. For the female suicide rate, the link was insignificant. It was found that the moderating effect of built-up areas was estimated as negative, while the effect of population density was positive. These findings were only partially according to the literature, as we expected that both effects will be negative. The moderating effects of greenery and divorce rate were estimated as insignificant. However, the validity of these findings is questionable, as the goodness of fit measures are poor and were increased only after increasing the level of aggregation from NUTS4 to NUTS3Práca skúma vzťah medzi nezamestnanosťou a samovražednosťou v českých a slovenských okresoch v rokoch 2002 až 2020 pomocou fixed-effects (within) modelu. Práca našla pozitívny vzťah medzi samovražednosťou a nezamestnanosťou u mužov, pre ženy bol efekt štatisticky nevýznamný. Zistili sme, že efekt interakcie proporcie zastavaných území s nezamestnanosťou je negatívny, zatiaľčo efekt interakcie hustoty obyvateľstva a nezamestnanosti je pozitívny. Tieto zistenia boli iba čiastočne v súlade s literatúrou; očakávali sme, že oba efekty prostredia budú negatívne. Interakcie nezamestnanosti s množstvom ze lene a mierou rozvodovosti boli štatisticky nevýznamné. Avšak, hodnota zistení je relatívne nízka, R2 modelu bolo extrémne nízke a zvýšilo sa až po zvýšení úrovne agregácie z NUTS4 na NUTS3.Institut ekonomických studiíInstitute of Economic StudiesFaculty of Social SciencesFakulta sociálních vě
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