Columns employed so far in capillary electrochromatography (CEC) contain both a packed and an open segment with concomitant changes of the electric field strength and the flow velocity at the interface of the two segments in such duplex columns. To take this into account in measuring, processing, and interpreting CEC data, a framework is presented for the evaluation of the conductivity ratio and the interstitial electrosmotic flow (EOF) mobility and their usage as tools for characterizing CEC columns. This is illustrated by experimental data obtained from measurement of the current and the EOF in capillary columns packed with different stationary phases. The current data yielded the ratio of the conductivities of the packed and open segments that has been shown to be useful for the evaluation of the porosity and tortuosity. It is assumed that these important packing characteristics are the same for the flow of current and for the flow of the bulk mobile phase in the CEC column. The EOF mobility in such duplex columns is defined in two different ways. The apparent mobility, which is widely reported at present, is obtained from the length of packed segment, the migration time, and the overall electric field strength. On the other hand, the actual mobility is obtained after taking into account the porosity and tortuosity of the packing as well. Thus, the actual mobility is made independent of the porosity and tortuosity and therefore can be useful to estimate the zeta potential for characterizing the packing surface. Measurements of both the apparent and actual electrosmotic mobilities for a number of different columns have shown that the apparent and actual mobilities are significantly different in their magnitude. For this reason, it is recommended that, instead of the apparent EOF mobility, the actual mobility is used for the characterization of the packing in CEC columns.
Conventional influenza vaccines can prevent infection, but their efficacy depends on the degree of antigenic "match" between the strains used for vaccine preparation and those circulating in the population. A universal influenza vaccine based on invariant regions of the virus, able to provide broadly cross-reactive protection, without requiring continuous manufacturing update, would solve a major medical need. Since the temporal and geographical dominance of the influenza virus type and/or subtype (A/H3, A/H1, or B) cannot yet be predicted, a universal vaccine, like the vaccines currently in use, should include both type A and type B influenza virus components. However, while encouraging preclinical data are available for influenza A virus, no candidate universal vaccine is available for influenza B virus. We show here that a peptide conjugate vaccine, based on the highly conserved maturational cleavage site of the HA 0 precursor of the influenza B virus hemagglutinin, can elicit a protective immune response against lethal challenge with viruses belonging to either one of the representative, non-antigenically cross-reactive influenza B virus lineages. We demonstrate that protection by the HA 0 vaccine is mediated by antibodies, probably through effector mechanisms, and that a major part of the protective response targets the most conserved region of HA 0 , the P1 residue of the scissile bond and the fusion peptide domain. In addition, we present preliminary evidence that the approach can be extended to influenza A virus, although the equivalent HA 0 conjugate is not as efficacious as for influenza B virus.
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