Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Class switch frequency

Jung, S., Siebenkotten, G. and Radbruch, A. (1994). Frequency of immunoglobulin E class switching is autonomously determined and independent of prior switching to other classes. J. Exp. Med. 179, 2023-2026. [Pg.49]

In polyclonally activated B cells class switch recombination precedes or rapidly follows the switch in CH-gene expression. Switching by a differential RNA splicing mechanism would apply for a very short period, if at all. The frequency of cells expressing surface IgG3 begins to increase after day 3 of LPS stimulation and already by day 6 about half of the IgH loci of these cells have performed switch recombination. [Pg.144]

Class switch recombination is also found to take place in plasmacytoma and hy-bridoma cells. These rare variant cells can be detected in many cell lines at frequencies of 1(T4 to 1CT7 (see Section 2.2.5.). In all cases analysed so far intermediate CH genes have been deleted from the active IgH loci. Frequently, however, the recombination sites were outside of the switch region - most drastically in the IgD variants (see review [C]), there being no switch sequence in front of C5 [56], This could be the reason why in normal B cells switching from IgM to IgD is rare upon activation. [Pg.144]

FIGURE 7.62 The half-wave Class D switch-mode pair in (a) produce power at the iiindamental component of the switching frequency. Near 100% efficiency may be achieved when the transistors are modeled as ideal switches. The on-resistance of the transistors and drain-source capacitance prevents 100% efficient operation. Drive waveform may be of any shape, but must transition through the on-off threshold region (- -4 V) very fast to avoid the active region. [Pg.605]

Quasi-resonant converters are a separate class of switching power supplies that tune the ac power waveforms to reduce or eliminate the switching loss within the supply. This is done by placing resonant tank circuits within the ac current paths to create pseudo-sinusoidal voltage or current waveforms. Because the tank circuits have one resonant frequency, the method of control needs to be modified to a variable frequency control where the resonant period is fixed and the control varies the period of the non-resonant period. The quasi-resonant converters usually operate in the 300 kHz to 2 MHz frequency range. [Pg.151]

The differences in the structures of the various switch regions raise the possibility of class-specific switch recombination, which would make no sense without a corresponding regulatory mechanism. It is known that the frequency of cells expressing various immunoglobulin classes can be regulated by T cell derived lym-phokines [3-9], although no lymphokine has been clearly demonstrated to induce the switch directly rather than to expand switched cells or switch precursors. [Pg.135]

Upon activation, the naive B cell stops to express IgD, starts secretion of IgM and, at a high frequency, is induced to a second type of switching (Fig. 3). This switch from IgM to any other immunoglobulin class is performed by repeated recombinations within and between switch regions through several rounds of replication. It occurs only in induced cells and on both IgH alleles. Lymphokines -switch factors - may be required to determine which switch regions are open for... [Pg.147]


See other pages where Class switch frequency is mentioned: [Pg.98]    [Pg.46]    [Pg.254]    [Pg.127]    [Pg.431]    [Pg.135]    [Pg.136]    [Pg.136]    [Pg.137]    [Pg.137]    [Pg.138]    [Pg.138]    [Pg.605]    [Pg.433]    [Pg.134]    [Pg.140]    [Pg.349]    [Pg.464]    [Pg.10]    [Pg.640]    [Pg.139]    [Pg.2765]    [Pg.31]    [Pg.313]    [Pg.160]    [Pg.208]    [Pg.211]    [Pg.2764]    [Pg.313]    [Pg.90]    [Pg.67]    [Pg.300]    [Pg.303]    [Pg.475]    [Pg.282]    [Pg.1297]    [Pg.17]    [Pg.987]    [Pg.678]    [Pg.151]   
See also in sourсe #XX -- [ Pg.136 ]




SEARCH



Class switch

Class switching

© 2024 chempedia.info