Simulations of string vibrations with boundary conditions of third kind using the functional transformation method.

The functional transformation method (FTM) is an established mathematical method for accurate simulation of multidimensional physical systems from various fields of science, including optics, heat and mass transfer, electrical engineering, and acoustics. It is a frequency-domain method based on the decomposition into eigenvectors and eigenfrequencies of the underlying physical problem. In this article, the FTM is applied to real-time simulations of vibrating strings which are ideally fixed at one end while the fixing at the other end is modeled by a frequency-dependent input impedance. Thus, boundary conditions of third kind are applied to the model at the end fixed with the input impedance. It is shown that accurate and stable simulations are achieved with nearly the same computational cost as with strings ideally fixed at both ends.

Frequent contribution of T cell clonotypes with public TCR features to the chronic response against a dominant EBV-derived epitope: application to direct detection of their molecular imprint on the human peripheral T cell repertoire.

In an attempt to provide a global picture of the TCR repertoire diversity of a chronic T cell response against a common Ag, we performed an extensive TCR analysis of cells reactive against a dominant HLA-A2-restricted EBV epitope (hereafter referred to as GLC/A2), obtained after sorting PBL or synovial fluid lymphocytes from EBV-seropositive individuals using MHC/peptide multimers. Although TCR beta-chain diversity of GLC/A2+ T cells was extensive and varied greatly from one donor to another, we identified in most cell lines several recurrent Vbeta subsets (Vbeta2, Vbeta4, and Vbeta16 positive) with highly conserved TCRbeta complementarity-determining region 3 (CDR3) length and junctional motifs, which represented from 11 to 98% (mean, 50%) of GLC/A2-reactive cells. While TCR beta-chains expressed by these subsets showed limited CDR1, CDR2, and CDR3 homology among themselves, their TCR alpha-chains comprised the same TCRAV region, thus suggesting hierarchical contribution of TCR alpha-chain vs TCR beta-chain CDR to recognition of this particular MHC/peptide complex. The common occurrence of T cell clonotypes with public TCR features within GLC/A2-specific T cells allowed their direct detection within unsorted PBL using ad hoc clonotypic primers. These results, which suggest an unexpectedly high contribution of public clonotypes to the TCR repertoire against a dominant epitope, have several implications for the follow-up and modulation of T cell-mediated immunity.

Detection of HBsAg in blood donors. A comparative study using radioimmunoassay, enzymeimmunoassay, reverse passive haemagglutination and latex tests.

Several "third generation" tests were compared: 5 reverse passive haemagglutination methods (RPHA), 2 enzyme immunoassays (EIA), 1 radioimmunoassay (RIA) and 1 latex test. As far as the sensitivity is concerned RPHA techniques are less sensitive than the RIA. However, differences exist among the different RPHA methods. RPHA methods which utilize human red cells demonstrated a better sensitivity than those which utilize animal red cells. The RIA is widely accepted for blood donor screening. The test is well standardized, highly sensitive and specific. Also the EIA has been found to be highly sensitive but showed a greater degree of non-specificity. Rapid HBsAg screening in blood donors can be performed by RPHA methods or by a latex test. For the latter Antigex TG was used. This test has a sensitivity which is similar to that of some the RPHA methods. The most striking results was the observation that Antigex TG can cause a prozone phenomenon. This phenomenon can be avoided when the serum specimen was spread out before the latex reagent was added.

[Experiences with an enzyme-immunoassay for hepatitis B antigen detection in blood donors (author's transl)]. / Erfahrungen mit einem Enzymimmunoassay zum Nachweis von Hepatitis B antigen bei Blutspendern.

In a comparative study 12,080 sera from unpaid donors were tested simultaneously for Hepatitis B Antigen (HBsAg) by enzyme-immunoassay (EIA) and radioimmunoassay (RIA). A relatively high number of sera reacted positive in the EIA-secreening test but were negative after repeated investigation. This percentage could be markedly reduced when using an automated washing apparatus. After neutralization 0.31 per cent were considered as true positive in EIA and RIA, thus demonstrating that no differences did exist as far as sensitivity is concerned. The EIA needs more incubation time than the RIA, however, the EIA has the advantage of using enzyme-labelled antibodies instead of radio-iodinated reagents. The results are read immediately and no sophisticated equipment is required. The EIA is easy to handle, two technicians can perform 1000 tests per day.