Differential binding to HLA-C of p50-activating and p58-inhibitory natural killer cell receptors

Natural killer (NK) cell cytotoxicity is regulated in large part by the expression of NK cell receptors able to bind class I major histocompatibility complex glycoproteins. The receptors associated with recognition of HLA-C allospecificities are the two-domain Ig-like molecules, p50 and p58 proteins, with highly homologous extracellular domains but differing in that they have either an activating or inhibitory function, respectively, depending on the transmembrane domain and cytoplasmic tails that they possess. We have compared the binding to HLA-Cw7 of an inhibitory p58 molecule, NKAT2, the highly homologous activating p50 molecule, clone 49, and a second activating p50 molecule, clone 39, which has homologies to both NKAT1 and NKAT2. NKAT2 binds to HLA-Cw7 with very rapid association and dissociation rates. However, the p50 receptors bind only very weakly, if at all, to HLA-C. The molecular basis of this difference is analyzed, and the functional significance of these observations is discussed.

The α1 domain of HLA-G1 and HLA-G2 inhibits cytotoxicity induced by natural killer cells: Is HLA-G the public ligand for natural killer cell inhibitory receptors?

We have investigated the protective role of the membrane-bound HLA-G1 and HLA-G2 isoforms against natural killer (NK) cell cytotoxicity. For this purpose, HLA-G1 and HLA-G2 cDNAs were transfected into the HLA class I-negative human K562 cell line, a known reference target for NK lysis. The HLA-G1 protein, encoded by a full-length mRNA, presents a structure similar to that of classical HLA class I antigens. The HLA-G2 protein, deduced from an alternatively spliced transcript, consists of the α1 domain linked to the α3 domain. In this study we demonstrate that (i) HLA-G2 is present at the cell surface as a truncated class I molecule associated with β2-microglobulin; (ii) NK cytolysis, observed in peripheral blood mononuclear cells and in polyclonal CD3− CD16+ CD56+ NK cells obtained from 20 donors, is inhibited by both HLA-G1 and HLA-G2; this HLA-G-mediated inhibition is reversed by blocking HLA-G with a specific mAb; this led us to the conjecture that HLA-G is the public ligand for NK inhibitory receptors (NKIR) present in all individuals; (iii) the α1 domain common to HLA-G1 and HLA-G2 could mediate this protection from NK lysis; and (iv) when transfected into the K562 cell line, both HLA-G1 and HLA-G2 abolish lysis by the T cell leukemia NK-like YT2C2 clone due to interaction between the HLA-G isoform on the target cell surface and a membrane receptor on YT2C2. Because NKIR1 and NKIR2, known to interact with HLA-G, were undetectable on YT2C2, we conclude that a yet-unknown specific receptor for HLA-G1 and HLA-G2 is present on these cells.

Cortical processing of change detection: Dissociation between natural vowels and two-frequency complex tones

We compared magnetoencephalographic responses for natural vowels and for sounds consisting of two pure tones that represent the two lowest formant frequencies of these vowels. Our aim was to determine whether spectral changes in successive stimuli are detected differently for speech and nonspeech sounds. The stimuli were presented in four blocks applying an oddball paradigm (20% deviants, 80% standards): (i) /α/ tokens as deviants vs. /i/ tokens as standards; (ii) /e/ vs. /i/; (iii) complex tones representing /α/ formants vs. /i/ formants; and (iv) complex tones representing /e/ formants vs. /i/ formants. Mismatch fields (MMFs) were calculated by subtracting the source waveform produced by standards from that produced by deviants. As expected, MMF amplitudes for the complex tones reflected acoustic deviation: the amplitudes were stronger for the complex tones representing /α/ than /e/ formants, i.e., when the spectral difference between standards and deviants was larger. In contrast, MMF amplitudes for the vowels were similar despite their different spectral composition, whereas the MMF onset time was longer for /e/ than for /α/. Thus the degree of spectral difference between standards and deviants was reflected by the MMF amplitude for the nonspeech sounds and by the MMF latency for the vowels.

La roca magica: Uses of natural zeolites in agriculture and industry

For nearly 200 years since their discovery in 1756, geologists considered the zeolite minerals to occur as fairly large crystals in the vugs and cavities of basalts and other traprock formations. Here, they were prized by mineral collectors, but their small abundance and polymineralic nature defied commercial exploitation. As the synthetic zeolite (molecular sieve) business began to take hold in the late 1950s, huge beds of zeolite-rich sediments, formed by the alteration of volcanic ash (glass) in lake and marine waters, were discovered in the western United States and elsewhere in the world. These beds were found to contain as much as 95% of a single zeolite; they were generally flat-lying and easily mined by surface methods. The properties of these low-cost natural materials mimicked those of many of their synthetic counterparts, and considerable effort has made since that time to develop applications for them based on their unique adsorption, cation-exchange, dehydration–rehydration, and catalytic properties. Natural zeolites (i.e., those found in volcanogenic sedimentary rocks) have been and are being used as building stone, as lightweight aggregate and pozzolans in cements and concretes, as filler in paper, in the take-up of Cs and Sr from nuclear waste and fallout, as soil amendments in agronomy and horticulture, in the removal of ammonia from municipal, industrial, and agricultural waste and drinking waters, as energy exchangers in solar refrigerators, as dietary supplements in animal diets, as consumer deodorizers, in pet litters, in taking up ammonia from animal manures, and as ammonia filters in kidney-dialysis units. From their use in construction during Roman times, to their role as hydroponic (zeoponic) substrate for growing plants on space missions, to their recent success in the healing of cuts and wounds, natural zeolites are now considered to be full-fledged mineral commodities, the use of which promise to expand even more in the future.

Onset of natural killer cell lymphomas in transgenic mice carrying a truncated HMGI-C gene by the chronic stimulation of the IL-2 and IL-15 pathway

Rearrangements of the high mobility group protein I-C (HMGI-C) gene, consisting in the loss of the carboxyl-terminal tail, have been frequently detected in benign human tumors of mesenchymal origin. We have previously demonstrated that transgenic (TG) mice carrying a truncated HMGI-C construct (HMGI-C/T) exhibit a giant phenotype together with a predominantly abdominal/pelvic lipomatosis. Here, we report that HMGI-C/T TG mice develop natural killer (NK)-T/NK cell lymphomas starting from 12 months of age. We found an increased expression of IL-2 and IL-15 proteins and their receptors in these lymphomas, and we demonstrate that HMGI-C/T protein positively regulates their expression in vitro. Therefore, the HMGI-C/T-mediated chronic stimulation of the IL-2/IL-15 pathway could be responsible for the onset of NK-T/NK cell lymphomas in HMGI-C/T TG mice.

Augmented Reality for preschoolers: an experience around Natural Sciences educational contents

Early education is a key element for the future success of students in the education system. This work analyzes the feasibility of using augmented reality contents with preschool students (four and five years old) as a tool for improving their learning process. A quasi experimental design based on a nonequivalent groups posttest-only design was used. A didactic unit has been developed around the topic “animals” by the participant teachers. The control group followed all the didactic activities defined in the developed didactic materials, while the experimental group was provided in addition with some augmented reality contents. Results show improved learning outcomes in the experimental group with respect to the control group.

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.2 1890

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.3 1893

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.3

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.2

On the initiation of boudinage and folding instabilities in layered elasto-visco-plastic solids - Insights from natural microstructures and numerical simulations

The present understanding of the initiation of boudinage and folding structures is based on viscosity contrasts and stress exponents, considering an intrinsically unstable state of the layer. The criterion of localization is believed to be prescribed by geometry-material interactions, which are often encountered in natural structures. An alternative localization phenomenon has been established for ductile materials, in which instability emerges for critical material parameters and loading rates from homogeneous conditions. In this thesis, conditions are sought under which this type of instability prevails and whether localization in geological materials necessarily requires a trigger by geometric imperfections. The relevance of critical deformation conditions, material parameters and the spatial configuration of instabilities are discussed in a geological context. In order to analyze boudinage geometries, a numerical eigenmode analysis is introduced. This method allows determining natural frequencies and wavelengths of a structure and inducing perturbations on these frequencies. In the subsequent coupled thermo-mechanical simulations, using a grain size evolution and end-member flow laws, localization emerges when material softening through grain size sensitive viscous creep sets in. Pinch-and-swell structures evolve along slip lines through a positive feedback between the matrix response and material bifurcations inside the layer, independent from the mesh-discretization length scale. Since boudinage and folding are considered to express the same general instability, both structures should arise independently of the sign of the loading conditions and for identical material parameters. To this end, the link between material to energy instabilities is approached by means of bifurcation analyses of the field equations and finite element simulations of the coupled system of equations. Boudinage and folding structures develop at the same critical energy threshold, where dissipative work by temperature-sensitive creep overcomes the diffusive capacity of the layer. This finding provides basis for a unified theory for strain localization in layered ductile materials. The numerical simulations are compared to natural pinch-and-swell microstructures, tracing the adaption of grain sizes, textures and creep mechanisms in calcite veins. The switch from dislocation to diffusion creep relates to strain-rate weakening, which is induced by dissipated heat from grain size reduction, and marks the onset of continuous necking. The time-dependent sequence uncovers multiple steady states at different time intervals. Microstructurally and mechanically stable conditions are finally expressed in the pinch-and-swell end members. The major outcome of this study is that boudinage and folding can be described as the same coupled energy-mechanical bifurcation, or as one critical energy attractor. This finding allows the derivation of critical deformation conditions and fundamental material parameters directly from localized structures in the field.

Statistical-physical models of man-made and natural radio noise : part IV, Determination of the first-order parameters of class A and B interference /

Issued Sept. 1978.

Conference on disease with natural foci and parasitological problems...[Moscow, Leningrad, Academy of Science USSR, 1959]

"Sponsored by the Academy of Sciences of the USSR (Zoological Institute, Leningrad) and the Academy of Medical Sciences (Institute of Epidemiology and Microbiology imeni)...N. F. Gamaley."

Prodrome of a work to aid the teaching of the vegetable materia medica by the natural families of plants in the Therapeutic Inst. of Philadelphia.

Mode of access: Internet.

The silk culture in the United States; embracing complete accounts of the latest and most approved modes of hatching, rearing and feeding the silk-worm, managing a cocoonery, reeling, spinning, and manufacturing the silk, &c. ... With brief historical sketches of the silk business, natural history of the silk-worm, the mulberry, &c. comp. from the most approved and reliable works ... To which is added Blydenburgh's Manual of the silk culture; statistics of silk imports, &c., &c.

"The work ... has been prepared ... with the aid of Mr. I. R. Barbour ... we have ... profited by the article on silk in Dr. Ures ... dictionary of arts and sciences, Mr. Bliss's report on silk ... to the legislature of Ohio, Mr. Colman's report to the Massachusetts legislature, &c.; while we have quoted entire The silk manual of ... Mr. Blydenburgh." Advertisement, p. [3]