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Clonal analysis of a human antibody response. Quantitation of precursors of antibody-producing cells and generation and characterization of monoclonal IgM, IgG, and IgA to rabies virus.
We quantitated and characterized the changes in the human B cell repertoire, at the clonal level, before and after immunization with rabies virus. Moreover, we generated 10 monoclonal cell lines producing IgM, IgG, and IgA antibodies to the virus. We found that in healthy subjects, not previously exposed to the virus, nearly 2% of the circulating B lymphocytes were committed to the production of antibodies that bound the virus. These B cells expressed the surface CD5 molecule. The antibodies they produced were polyreactive IgM that displayed a relatively low affinity for the virus components (Kd, 1.0-2.4 x 10(-6) g/microliters). After immunization, different anti-virus (IgG and IgA) antibody-producing cells consistently appeared in the circulation and increased from less than 0.005% to greater than 10% of the total B cells committed to the production of IgG and IgA, respectively. Most of such B cells do not express CD5 and produce monoreactive antibodies of high affinity for rabies virus (Kd, 6.5 x 10(-9) to 1.2 x 10(-10) g/microliters). One of these IgG mAbs efficiently neutralized rabies virus in vitro and in vivo, as detailed elsewhere (Dietzschold, B., P. Casali, Y. Ueki, M. Gore, C. E. Rupprecht, A. L. Notkins, and H. Koprowski, manuscript submitted for publication). Hybridization experiments using probes specific for the different human V gene segment families revealed that cell precursors producing low affinity IgM binding to rabies virus utilized a restricted number of VH gene segments (i.e., only members of the VHIIIb subfamily), whereas cell precursors producing high affinity IgG and IgA to rabies virus utilized an assortment of different VH gene segments (i.e., members of the VHI, VHIII, VHIV, and VHVI families and VHIIIb subfamily). In conclusion, our studies show that EBV transformation in conjunction with limiting dilution technology and somatic cell hybridization techniques are useful methods for quantitating, at the B cell clonal level, the human antibody response to foreign Ags and for generating human mAbs of predetermined specificity and high affinity
Existence and uniqueness of the integrated density of states for Schr\"odinger operators with magnetic fields and unbounded random potentials
The object of the present study is the integrated density of states of a
quantum particle in multi-dimensional Euclidean space which is characterized by
a Schr\"odinger operator with a constant magnetic field and a random potential
which may be unbounded from above and from below. For an ergodic random
potential satisfying a simple moment condition, we give a detailed proof that
the infinite-volume limits of spatial eigenvalue concentrations of
finite-volume operators with different boundary conditions exist almost surely.
Since all these limits are shown to coincide with the expectation of the trace
of the spatially localized spectral family of the infinite-volume operator, the
integrated density of states is almost surely non-random and independent of the
chosen boundary condition. Our proof of the independence of the boundary
condition builds on and generalizes certain results by S. Doi, A. Iwatsuka and
T. Mine [Math. Z. {\bf 237} (2001) 335-371] and S. Nakamura [J. Funct. Anal.
{\bf 173} (2001) 136-152].Comment: This paper is a revised version of the first part of the first
version of math-ph/0010013. For a revised version of the second part, see
math-ph/0105046. To appear in Reviews in Mathematical Physic
Low lying spectrum of weak-disorder quantum waveguides
We study the low-lying spectrum of the Dirichlet Laplace operator on a
randomly wiggled strip. More precisely, our results are formulated in terms of
the eigenvalues of finite segment approximations of the infinite waveguide.
Under appropriate weak-disorder assumptions we obtain deterministic and
probabilistic bounds on the position of the lowest eigenvalue. A Combes-Thomas
argument allows us to obtain so-called 'initial length scale decay estimates'
at they are used in the proof of spectral localization using the multiscale
analysis.Comment: Accepted for publication in Journal of Statistical Physics
http://www.springerlink.com/content/0022-471
A New Experimental Approach to Evaluate Plasma-induced Damage in Microcantilever
Plasma etching, during micro-fabrication processing is indispensable for fabricating MEMS structures. During the plasma processes, two major matters, charged ions and vacuum–ultraviolet (VUV) irradiation damage, take charge of reliability degradation. The charged ions induce unwanted sidewall etching, generally called as “notching”, which causes degradation in brittle strength. Furthermore, the VUV irradiation gives rise to crystal defects on the etching surface. To overcome the problem, neutral beam etching (NBE), which use neutral particles without the VUV irradiation, has been developed. In order to evaluate the effect of the NBE quantitatively, we measured the resonance property of a micro-cantilever before and after NBE treatment. The thickness of damage layer (δ) times the imaginary part of the complex Young's modulus (Eds) were then compared, which is a parameter of surface damage. Although plasma processes make the initial surface of cantilevers damaged during their fabrication, the removal of that damage by NBE was confirmed as the reduction in δEds. NBE will realize a damage-free surface for microstructures
Wettability characteristics of an Al2O3/SiO2-based ceramic modified with CO2, Nd:YAG, excimer and high-power diode lasers
Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the
surface of an Al2O3/SiO2 based ceramic was found to effect significant changes in the
wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG
and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330
respectively. In contrast, interaction with excimer laser radiation resulted an increase in the
contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial
vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2,
Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic
increasing after interaction with excimer laser radiation. (iii) the surface oxygen content of the
Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation.
The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could
be controlled and/or modified with laser surface treatment. In particular, whether the laser
radiation had the propensity to cause surface melting. However, a wavelength dependance of
the change of the wetting properties could not be deduced from the findings of this work
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