Analysis of mechanics of side impact test defined in UN/ECE Regulation 129

<p><b>Objective</b>: This article discusses differences between a side impact procedure described in United Nations/Economic Commission for Europe (UN/ECE) Regulation 129 and scenarios observed in real-world cases.</p> <p><b>Methods</b>: Numerical simulations of side impact tests utilizing different boundary conditions are used to compare the severity of the Regulation 129 test and the other tests with different kinematics of child restraint systems (CRSs). In the simulations, the authors use a validated finite element (FE) model of real-world CRSs together with a fully deformable numerical model of the Q3 anthropomorphic test device (ATD) by Humanetics Innovative Solution, Inc.</p> <p><b>Results</b>: The comparison of 5 selected cases is based on the head injury criterion (HIC) index. Numerical investigations reveal that the presence of oblique velocity components or the way in which the CRS is mounted to the test bench seat fixture is among the significant factors influencing ATD kinematics. The results of analyses show that the side impact test procedure is very sensitive to these parameters. A side impact setup defined in Regulation 129 may minimize the effects of the impact.</p> <p><b>Conclusions</b>: It is demonstrated that an artificial anchorage in the Regulation 129 test does not account for a rotation of the CRS, which should appear in the case of a realistic anchorage. Therefore, the adopted procedure generates the smallest HIC value, which is at the level of the far-side impact scenario where there are no obstacles. It is also shown that the presence of nonlateral acceleration components challenges the quality of a CRS and its headrest much more than a pure lateral setup.</p

Modification of Lipooligosaccharide with Phosphoethanolamine by LptA in Neisseria meningitidis Enhances Meningococcal Adhesion to Human Endothelial and Epithelial Cells▿

The lipooligosaccharide (LOS) of Neisseria meningitidis can be decorated with phosphoethanolamine (PEA) at the 4′ position of lipid A and at the O-3 and O-6 positions of the inner core of the heptose II residue. The biological role of PEA modification in N. meningitidis remains unclear. During the course of our studies to elucidate the pathogenicity of the ST-2032 (invasive) meningococcal clonal group, disruption of lptA, the gene that encodes the PEA transferase for 4′ lipid A, led to a approximately 10-fold decrease in N. meningitidis adhesion to four kinds of human endothelial and epithelial cell lines at an multiplicity of infection of 5,000. Complementation of the lptA gene in a ΔlptA mutant restored wild-type adherence. By matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analysis, PEA was lost from the lipid A of the ΔlptA mutant compared to that of the wild-type strain. The effect of LptA on meningococcal adhesion was independent of other adhesins such as pili, Opc, Opa, and PilC but was inhibited by the presence of capsule. These results indicate that modification of LOS with PEA by LptA enhances meningococcal adhesion to human endothelial and epithelial cells in unencapsulated N. meningitidis

Biochemical characterization of Sinorhizobium meliloti mutants reveals gene products involved in the biosynthesis of the unusual lipid a very long-chain fatty acid

Sinorhizobium meliloti forms a symbiosis with the legume alfalfa, whereby it differentiates into a nitrogen-fixing bacteroid. The lipid A species of S. meliloti are modified with very long-chain fatty acids (VLCFAs), which play a central role in bacteroid development. A six-gene cluster was hypothesized to be essential for the biosynthesis of VLCFA-modified lipid A. Previously, two cluster gene products, AcpXL and LpxXL, were found to be essential for S. meliloti lipid A VLCFA biosynthesis. In this paper, we show that the remaining four cluster genes are all involved in lipid A VLCFA biosynthesis. Therefore, we have identified novel gene products involved in the biosynthesis of these unusual lipid modifications. By physiological characterization of the cluster mutant strains, we demonstrate the importance of this gene cluster in the legume symbiosis and for growth in the absence of salt. Bacterial LPS species modified with VLCFAs are substantially less immunogenic than Escherichia coli LPS species, which lack VLCFAs. However, we show that the VLCFA modifications do not suppress the immunogenicity of S. meliloti LPS or affect the ability of S. meliloti to induce fluorescent plant defense molecules within the legume. Because VLCFA-modified lipids are produced by other rhizobia and mammalian pathogens, these findings will also be important in understanding the function and biosynthesis of these unusual fatty acids in diverse bacterial species

A glycan receptor kinase facilitates intracellular accommodation of arbuscular mycorrhiza and symbiotic rhizobia in the legume Lotus japonicus.

Receptors that distinguish the multitude of microbes surrounding plants in the environment enable dynamic responses to the biotic and abiotic conditions encountered. In this study, we identify and characterise a glycan receptor kinase, EPR3a, closely related to the exopolysaccharide receptor EPR3. Epr3a is up-regulated in roots colonised by arbuscular mycorrhizal (AM) fungi and is able to bind glucans with a branching pattern characteristic of surface-exposed fungal glucans. Expression studies with cellular resolution show localised activation of the Epr3a promoter in cortical root cells containing arbuscules. Fungal infection and intracellular arbuscule formation are reduced in epr3a mutants. In vitro, the EPR3a ectodomain binds cell wall glucans in affinity gel electrophoresis assays. In microscale thermophoresis (MST) assays, rhizobial exopolysaccharide binding is detected with affinities comparable to those observed for EPR3, and both EPR3a and EPR3 bind a well-defined β-1,3/β-1,6 decasaccharide derived from exopolysaccharides of endophytic and pathogenic fungi. Both EPR3a and EPR3 function in the intracellular accommodation of microbes. However, contrasting expression patterns and divergent ligand affinities result in distinct functions in AM colonisation and rhizobial infection in Lotus japonicus. The presence of Epr3a and Epr3 genes in both eudicot and monocot plant genomes suggest a conserved function of these receptor kinases in glycan perception