Autotaxin, an ectoenzyme that produces lysophosphatidic acid, promotes the entry of lymphocytes into secondary lymphoid organs

The extracellular lysophospholipase D autotaxin (ATX) and its product, lysophosphatidic acid, have diverse functions in development and cancer, but little is known about their functions in the immune system. Here we found that ATX had high expression in the high endothelial venules of lymphoid organs and was secreted. Chemokine-activated lymphocytes expressed receptors with enhanced affinity for ATX, which provides a mechanism for targeting the secreted ATX to lymphocytes undergoing recruitment. Lysophosphatidic acid induced chemokinesis in T cells. Intravenous injection of enzymatically inactive ATX attenuated the homing of T cells to lymphoid tissues, probably through competition with endogenous ATX and exertion of a dominant negative effect. Our results support the idea of a new and general step in the homing cascade in which the ectoenzyme ATX facilitates the entry of lymphocytes into lymphoid organs

Nepmucin, a novel HEV sialomucin, mediates L-selectin–dependent lymphocyte rolling and promotes lymphocyte adhesion under flow

Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin contains a single V-type immunoglobulin (Ig) domain and a mucin-like domain. Using materials affinity-purified from LN lysates with soluble L-selectin, we found that two higher molecular weight species of nepmucin (75 and 95 kD) were decorated with oligosaccharides that bind L-selectin as well as an HEV-specific MECA-79 monoclonal antibody. Electron microscopic analysis showed that nepmucin accumulates in the extended luminal microvillus processes of LN HEVs. Upon appropriate glycosylation, nepmucin supported lymphocyte rolling via its mucin-like domain under physiological flow conditions. Furthermore, unlike most other sialomucins, nepmucin bound lymphocytes via its Ig domain, apparently independently of lymphocyte function–associated antigen 1 and very late antigen 4, and promoted shear-resistant lymphocyte binding in combination with intercellular adhesion molecule 1. Collectively, these results suggest that nepmucin may serve as a dual-functioning PNAd in LN HEVs, mediating both lymphocyte rolling and binding via different functional domains

Angular distributions of atoms sputtered by ion bombarding

The apparatus for measuring angular distributions of atoms sputtered from metals by ion bomberding has been constructed. It has a hollow cathode type ion source, an ion beam focusing system and a target chamber in which a target and collectors of sputtered atoms are set. The angular distributions of the sputtered atoms have been measured using inert gas, copper and silver ions and two metals. A rotating target is used to collect quantitative amounts of atoms for atomic absorption analyses on collectors with a possibly low ion dose, since a high ion dose erodes topographically a target surface probably to affect the angular distributions. It has been observed that the atoms sputtered in the opposite direction to an ion beam incidence decease as the ion dose becomes high and mass ratio of the ion to the target atom increases

Activation Analysis of Some Metals Sticking on a Si-Wafer

The neutron activation analysis was used to identify elements and measure quantitatively the number of metalic atoms sticked on a Si-wafer which was a single crystal of 10 mm×10 mm×0.2 mm. In order to obtain measuring effciencies and limits in the analysis, the metalic samples of V, Fe, Ni and Cu were irradiated by neutrons from a reactor. The γ-rays from the activated samples were analyzed by means of a γ-ray spectrometer connected to a data acquisition and processing system. The limits of detection obtained are 0.2μg for V;500μg, Fe;2μg， Ni;1μg, Cu. These values are valid under the condition that the elements associated with the Siwafer mentioned above are packaged in the bag made of a sheet of polyethylene with 25 mm×50 mm×0.03 mm in size. The predicted values by Currie\u27s formula for the limits of detection are fairly consistent with the experimental ones. It is also found that if the lower values of detection Iimits are desired, further care should be taken to reduce the background resulted dominantly from the γ-rays emitted from ^<24>Na and ^<41>Ar contained in the package bag of polyethylene sheet

A Helium Atom Measurement System using for the Helium Accumulation Method in Neutron Dosimetry

In the helium accumulation method for neutron dosimetry, it is applied that the number of helium atoms produced through (n,xα) reaction is proportional to neutron fluence in fast neutron irradiation fields. Besides, activities measuring in the activation method saturate to the value depending on their half-lives. A helium atom measurement, system for detecting of helium atoms accumulated in neutron-irradiated samples has been constructed and tested. The samples are vaporized in a furnace to release helium contained in them. The number of helium atoms is measured with a quadrupole mass spectrometer calibrated by a standard helium gas supply which is consist of a known-volume vessel, a pressure gauge and a thermometer. It has been proposed in this work that helium-ion implanted aluminum disks are applied to calibrate the helium atom measurement system. This method has succeeded to obtain results agreed with the standard helium gas supply system