Microscopic Observation of Leukocyte Kinesis in the Vascular Bed during Hemodialysis Using the Rabbit Ear Chamber Technique

Leukocyte kinesis in the capillary vascular bed during hemodialysis (HD) was investigated to elucidate the mechanism of transient leukopenia. Leukocyte movement was observed microscopically during HD using the rabbit ear chamber (REC) technique, which permits visualization of the movement of blood corpuscles in capillaries. Blood was drawn from the femoral artery and returned into the auricular and/or carotid artery so that the blood passing through the hollow fiber artificial kidney (HFAK) flowed into capillaries in the REC. Leukocyte counts of blood samples taken from the afferent and efferent limbs of the HD circuit, the right jugular vein and the right atrium were determined consecutively during HD. The difference in the leukocyte count was observed between the afferent and efferent limbs for the first 15 minutes and thereafter between the efferent limb and the jugular vein. The “transpulmonary” difference in the leukocyte count was not noticed throughout HD. Between 15 and 90 minutes after the start of HD, scarcely any circulating leukocytes were found in capillaries in the REC and some leukocytes were attached to the endothelial surface. Thereafter circulating leukocytes were seen again and detachment of leukocytes from the endothelial surface was observed. No leukocyte aggregation or embolization of aggregating leukocytes was noticed. This evidence suggests that leukopenia may be attributed to the transient shift of leukocytes to the marginal pool of the vessel lumen and this process may not be specific for the pulmonary vasculature, but may occur in the first capillary bed into which the blood passing through the HFAK flows. The attachment of leukocytes to the surface membrane of the HFAK may contribute to the transient leukopenia especially during the initial period of the HD.

Measurements of Multiparticle Correlations in d+Au Collisions at 200, 62.4, 39, and 19.6 GeV and p+Au Collisions at 200 GeV and Implications for Collective Behavior

Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of two-, four-, and six-particle angular correlations in d+Au collisions at sqrt[s_{NN}]=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrt[s_{NN}]=200  GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200 GeV

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Distribution of anaerobic carbon monoxide dehydrogenase genes in deep subseafloor sediments

Carbon monoxide (CO) is the simplest oxocarbon generated by the decomposition of organic compounds, and it is expected to be in marine sediments in substantial amounts. However, the availability of CO in the deep subseafloor sedimentary biosphere is largely unknown even though anaerobic oxidation of CO is a thermodynamically favourable reaction that possibly occurs with sulphate reduction, methanogenesis, acetogenesis and hydrogenesis. In this study, we surveyed for the first time the distribution of the CO dehydrogenase gene (cooS), which encodes the catalytic beta subunit of anaerobic CO dehydrogenase (CODH), in subseafloor sediment-core samples from the eastern flank of the Juan de Fuca Ridge, Mars-Ursa Basin, Kumano Basin, and off the Shimokita Peninsula, Japan, during Integrated Ocean Drilling Program (IODP) Expeditions 301, 308 and 315 and the D/V Chikyu shakedown cruise CK06-06, respectively. Our results show the occurrence of diverse cooS genes from the seafloor down to about 390 m below the seafloor, suggesting that microbial communities have metabolic functions to utilize CO in anoxic microbial ecosystems beneath the ocean floor, and that the microbial community potentially responsible for anaerobic CO oxidation differs in accordance with possible energy-yielding metabolic reactions in the deep subseafloor sedimentary biosphere.

SIGNIFICANCE AND IMPACT OF THE STUDY

Little is known about the microbial community associated with carbon monoxide (CO) in the deep subseafloor. This study is the first survey of a functional gene encoding anaerobic carbon monoxide dehydrogenase (CODH). The widespread occurrence of previously undiscovered CO dehydrogenase genes (cooS) suggests that diverse micro-organisms are capable of anaerobic oxidation of CO in the deep subseafloor sedimentary biosphere.

Differential and Quantitative Analyses of mRNA Expression of Glucosyltransferases from Streptococcus mutans MT8148

Streptococcus mutans produces three glucosyltransferases, coded by gtfB, gtfC, and gtfD, whose cooperative action is essential for sucrose-dependent cellular adhesion. This cellular adhesion plays an important role in the formation of dental plaque and the initiation of dental caries. Since they bear genetic similarities and are large in size, differentiation of their gene expression has been difficult, and little is known about the dynamic process of gtf expression. Using a real-time reverse-transcription/polymerase chain-reaction, we determined the expression of each gtf. Under various conditions, the relative levels of transcription were gtfB > gtfD > gtfC. Sucrose enhanced gtfD expression, whereas it reduced that of gtfB and gtfC, suggesting the presence of independent promoters. Quantitative analyses demonstrated coincidence between the ratio of expression of each gtf and the ratio previously identified as optimal for sucrose-dependent adhesion in vitro, suggesting that S. mutans produces GTF at an optimal ratio to adhere to the tooth surface.

Correction: β-Amyrin synthase from Euphorbia tirucalli L. functional analyses of the highly conserved aromatic residues Phe413, Tyr259 and Trp257 disclose the importance of the appropriate steric bulk, and cation–π and CH–π interactions for the efficient catalytic action of the polyolefin cyclization cascade

Correction for ‘β-Amyrin synthase from Euphorbia tirucalli L. functional analyses of the highly conserved aromatic residues Phe413, Tyr259 and Trp257 disclose the importance of the appropriate steric bulk, and cation–π and CH–π interactions for the efficient catalytic action of the polyolefin cyclization cascade’ by Ryousuke Ito et al., Org. Biomol. Chem., 2017, 15, 177–188.

β-Amyrin biosynthesis: catalytic mechanism and substrate recognition

In the past five years, there have been remarkable advances in the study of β-amyrin synthase. This review outlines the catalytic mechanism and substrate recognition in β-amyrin biosynthesis, which have been attained by the site-directed mutagenesis and substrate analog experiments.

β-Amyrin synthase from Euphorbia tirucalli L. functional analyses of the highly conserved aromatic residues Phe413, Tyr259 and Trp257 disclose the importance of the appropriate steric bulk, and cation-π and CH-π interactions for the efficient catalytic action of the polyolefin cyclization cascade

Many of the functions of the active site residues in β-amyrin synthase and its catalytic mechanism remain unclear. Herein, we examined the functions of the highly conserved Phe413, Tyr259, and Trp257 residues in the β-amyrin synthase of Euphorbia tirucalli. The site-specific mutants F413V and F413M [corrected] showed nearly the same enzymatic activities as the wild type, indicating that π-electrons are not needed for the catalytic reaction. However, the F413A [corrected] mutant yielded a large amount of the tetracyclic dammarane skeleton, with decreased production of β-amyrin. This indicates that the Phe413 [corrected] residue is located near the D-ring formation site and works to position the oxidosqualene substrate correctly within the reaction cavity. On the other hand, the major catalysis-related function of the Tyr259 and Trp257 residues is to yield their π-electrons to the cationic intermediates. The Y259F variant showed nearly equivalent activity to that of the wild type, but aliphatic mutants such as the Ala, Val, and Leu variants showed significantly decreased the activity and yielded the tetracyclic dammarane scaffold, strongly demonstrating that the Tyr259 residue stabilizes the baccharenyl secondary cation via cation-π interaction. The aliphatic variants of Trp257 exhibited remarkably decreased enzymatic activity, and lupeol was produced in a high production ratio, indicating that Trp257 stabilizes the oleanyl cation via cation-π interaction. The aromatic Phe and Tyr mutants exhibited high activities owing to their more increased π-electron density relative to that of the aliphatic mutants, but lupeol was produced in a significantly high yield besides β-amyrin. The Trp residue is likely to be responsible for the robust binding of Me-30 through CH-π interaction. The decreased π-electron density of the Phe and Tyr mutants compared to that of Trp would have resulted in the high production of lupeol.