Fc receptor binding of anti-CD3 monoclonal antibodies is not essential for immunosuppression, but triggers cytokine-related side effects

A major drawback to the use of OKT3, a mouse anti-CD3 monoclonal antibody (mAb), as an immunosuppressive agent is the associated cytokine release syndrome. We used a mouse model to elucidate the properties of anti-CD3 mAb responsible for these cytokine-related side effects. We have previously demonstrated that the hamster anti-CD3 mAb 145-2C11 induced strong cytokine release and morbidity in vivo, whereas two rat anti-CD3 mAb 17A2 and KT3 did not. In the current study, we show that the mitogenic capacity of soluble anti-CD3 mAb in vitro correlates with their induction of side effects in vivo. Mitogenesis in vitro and tumor necrosis factor-α (TNF-α) release in vivo induced by anti-CD3 mAb could be inhibited by the anti-FcγR mAb 2.4G2, indicating that FcγR binding of anti-CD3 mAb is responsible for their mitogenic properties and for their induction of side effects. Importantly, the two non-mitogenic rat anti-CD3 mAb were equally capable of suppressing skin allograft rejection as the mitogenic hamster anti-CD3 mAb, suggesting FcγR binding of anti-CD3 mAb is not essential for their immunosuppressive properties. This suggestion is reinforced by our demonstration that administration of 2.4G2 in vivo did not interfere with immunosuppression of skin allograft rejection by 145-2C11. These findings suggest that clinical use of non-mitogenic anti-CD3 mAb will result in effective immunosuppression without cytokine-related side effects

Wideband synthetic aperture sonar backprojection with maximization of wave number domain support

Wideband and widebeam synthetic aperture sonar (SAS) can provide information on the frequency- and aspect-dependent scattering in a scene. We suggest an approach to predict the quality of the sensor data over the available frequencies and aspect angles. We relate the typical spatial domain quality metrics to their wave number domain (WD) counterpart, and use these to map the data quality in WD. Because SAS arrays often are undersampled along-track, we pay particular attention to data degradation from aliasing. We use the proposed approach to examine how three SAS image formation algorithms based on time domain backprojection (TDBP) access data of different quality from wideband SAS systems. We illustrate the results with predictions for a generic SAS design and demonstrate the findings on two experimental systems. We observe that the maximum support of high-quality data is achieved through BP onto a high-resolution grid followed by WD filtering.<br/

Deconvolution of land seismic data for source and receiver characteristics and near-surface structure

Seismic reflection methods are widely used for the detection of hydrocarbons in subsurface structures up to several kilometers depth. However, since most data are acquired at or close to the Earth's surface, it is essential to understand the influence of the near-surface on the acquired data in order that its effects are not interpreted as pertaining to the reservoir. The near-surface effect on seismic data has two main origins: (i) near-surface wave propagation and (ii) wavefield acquisition. Wavefield acquisition comprises both wavefield excitation and wavefield measurement, i.e. source and receiver effects. Since both P- and S-wave velocities are observed to vary rapidly close to the Earth's surface, wave propagation in the near-surface is often very complex. In order to improve our understanding of near-surface wave propagation, we investigated and developed methods to determine near-surface P- and S-wave velocities. For this purpose, we used dense recording geometries including buried geophones, since these material properties cannot be resolved with a conventional acquisition geometry using geophones only at the free surface. One of the methods developed is based on the estimation and inversion of the propagator matrix, and therefore referred to as propagator inversion. The propagator inversion was applied to data which we acquired in Zeist, The Netherlands. We obtained a low near-surface P velocity, namely 270 ± 15 m/s, which is well below the sound velocity in air, and 150 ± 9 m/s for the S velocity. The buried geophone was located at approximately 1.0 m depth, thus the obtained velocities are only representative of the top meter of the near-surface. The second part of this thesis is devoted to the influence of wavefield acquisition. Corrections for source and receiver perturbations are necessary when their behaviour changes within a given survey, and should be performed in the early stages of processing. However, existing techniques, such as surface-consistent deconvolution, require prior processing before even they can be applied. We developed an alternative approach to compensate for source and receiver amplitude perturbations which has the advantage of being purely a raw data preprocessing step. It is applicable to the whole seismic trace, and does not impose additional assumptions on the subsurface. The approach is based on reciprocity of the medium response. This implies that differences between normal and reciprocal traces can be attributed to the source and receiver perturbations. We successfully demonstrated the procedure to compensate for these perturbations on both synthetic and field data. The field data were acquired in Manistee County, Michigan (courtesy of WesternGeco). Along the acquisition line, near-surface conditions change from moist-to-wet sediments to dry sands. The obtained source corrections are strongly correlated to these changing near-surface conditions, whereas the receiver corrections vary more strongly from geophone to geophone. Compensation of the recorded data for the source and receiver perturbations resulted in a significant improvement of the signal-to-noise ratio, both on prestack and poststack data. Finally, the receiver response we found did not agree with the generally accepted damped harmonic oscillator model, implying that this model need to be revised

“Full-waveform static corrections using blind channel identification,” <i>Robbert van Vossen and Jeannot Trampert</i>, G<scp>EOPHYSICS</scp>, <b>72</b>, no. 4, U55–U66.

Figure 15 appeared distorted. We apologize for any inconvenience caused by this error. </jats:p

The effect of wind-generated bubbles on sea-surface backscattering at 940 Hz

Reliable predictions of sea-surface backscattering strength are required for sonar performance modeling. These are, however, difficult to obtain as measurements of sea-surface backscattering are not available at small grazing angles relevant to low-frequency active sonar (1-3 kHz). Accurate theoretical predictions of scattering strength require a good understanding of physical mechanisms giving rise to the scattering and the relative importance of these. In this paper, scattering from individual resonant bubbles is introduced as a potential mechanism and a scattering model is derived that incorporates the contribution from these together with that of rough surface scattering. The model results are fitted to Critical Sea Test (CST) measurements at a frequency of 940 Hz, treating the number of large bubbles, parameterized through the spectral slope of the size spectrum for bubbles whose radii exceed 1 mm, as a free parameter. This procedure illustrates that the CST data can be explained by scattering from a small number of large resonant bubbles, indicating that these provide an alternative mechanism to that of scattering from bubble clouds. © 2011 Acoustical Society of America