Heparin increases the antibiotic efficacy of colistin

The increasing antibiotic resistance in bacteria is an alarming phenomenon all around the world. Certain strains have developed resistance against multiple antimicrobial molecules, in which cases, the final option is to use a last-resort drug. These drugs, however, are last-resort for a reason: they can pose serious risk on vital organ functions in the patient. To mitigate the risk of severe side-effects and to reduce the rate of bacterial mutation, co-administration with other molecules that increase their efficacy seems to be the only suitable option. This leads to a reduced dose while maintaining the same level of antibiotic activity within the body. In this study, the effect of heparin derivatives on the antibiotic activity of colistin and their interactions were studied by ion mobility, mass spectrometry, and bacterium growth assays. The results show that during the association of colistin and heparin, they retain their structure while higher-stoichiometry complexes can form. When long-chain heparin is co-administered, multiple colistin molecules can associate with it, which increases the antibiotic activity by ∼40% relative to the sole administration of colistin

Adaptive stopping criterion for top-down segmentation of ALS point clouds in temperate coniferous forests

The development of new approaches to individual tree crown delineation for forest inventory and management is an important area of ongoing research. The increasing availability of high density ALS (Airborne Laser Scanning) point clouds offers the opportunity to segment the individual tree crowns and deduce their geometric properties with a high level of accuracy. Top-down segmentation methods such as normalized cut are established approaches for delineation of single trees in ALS point clouds. However, overlapping crowns and branches of nearby trees frequently cause over- and under-segmentation due to the difficulty of defining a single criterion for stopping the partitioning process. In this work, we investigate an adaptive stopping criterion based on the visual appearance of trees within the point clouds. We focus on coniferous trees due to their well-defined crown shapes in comparison to deciduous trees. This approach is based on modeling the coniferous tree crowns with elliptic paraboloids to infer whether a given 3D scene contains exactly one or more than one tree. For each processed scene, candidate tree peaks are generated from local maxima found within the point cloud. Next, paraboloids are fitted at the peaks using a random sample consensus procedure and classified based on their geometric properties. The decision to stop or continue partitioning is determined by finding a set of non-overlapping paraboloids. Experiments were performed on three plots from the Bavarian Forest National Park in Germany. Based on validation data from the field inventory, results show that our approach improves the segmentation quality by up to 10% across plots with different properties, such as average tree height and density. This indicates that the new adaptive stopping criterion for normalized cut segmentation is capable of delineating tree crowns more accurately than a static stopping criterion based on a constant Ncut threshold value

Estimation of regeneration coverage in a temperate forest by 3D segmentation using airborne laser scanning data

Forest understory and regeneration are important factors in sustainable forest management. However, understanding their spatial distribution in multilayered forests requires accurate and continuously updated field data, which are difficult and time-consuming to obtain. Therefore, cost-efficient inventory methods are required, and airborne laser scanning (ALS) is a promising tool for obtaining such information. In this study, we examine a clustering-based 3D segmentation in combination with ALS data for regeneration coverage estimation in a multilayered temperate forest. The core of our method is a two-tiered segmentation of the 3D point clouds into segments associated with regeneration trees. First, small parts of trees (super-voxels) are constructed through mean shift clustering, a nonparametric procedure for finding the local maxima of a density function. In the second step, we form a graph based on the mean shift clusters and merge them into larger segments using the normalized cut algorithm. These segments are used to obtain regeneration coverage of the target plot. Results show that, based on validation data from field inventory and terrestrial laser scanning (TLS), our approach correctly estimates up to 70% of regeneration coverage across the plots with different properties, such as tree height and tree species. The proposed method is negatively impacted by the density of the overstory because of decreasing ground point density. In addition, the estimated coverage has a strong relationship with the overstory tree species composition.</p

Lyn and PECAM-1 function as interdependent inhibitors of platelet aggregation

Inhibition of platelet responsiveness is important to control pathologic thrombus formation. Platelet–endothelial cell adhesion molecule-1 (PECAM-1) and the Src family kinase Lyn inhibit platelet activation by the glycoprotein VI (GPVI) collagen receptor; however, it is not known whether PECAM-1 and Lyn function in the same or different inhibitory pathways. In these studies, we found that, relative to wild-type platelets, platelets derived from PECAM-1–deficient, Lyn-deficient, or PECAM-1/Lyn double-deficient mice were equally hyperresponsive to stimulation with a GPVI-specific agonist, indicating that PECAM-1 and Lyn participate in the same inhibitory pathway. Lyn was required for PECAM-1 tyrosine phosphorylation and subsequent binding of the Src homology 2 domain–containing phosphatase-2, SHP-2. These results support a model in which PECAM-1/SHP-2 complexes, formed in a Lyn-dependent manner, suppress GPVI signaling