Congenic resistant strains

Congenic resistant strains are inbred strains which are genetically identical to some standard inbred strain, such as C57BL/10 (BIO), except for the substitution of a distinct H-2 chromosomal segment from another strain. Thus a series of such strains may exist, all identical except that each carries a different set of H-2 genes. 

In vitro cultures of spleen cells from inbred and congenic-resistant strains in the presence of 1 or 10 lug of soluble GAT have shown identical results as those observed in vivo. Soluble GAT in these concentrations stimulates the development of IgG GAT-specific PFC responses in cultures of spleen cells from responder C57BL/6 (H-2 ), Fi(C57 x SJL) (H-2 ) and A/J (H-2") mice. Soluble GAT did not stimulate the development of GAT-specific PFC responses in cultures of spleen cells from non-responder H-2 mice (SJL, BIO.S, A.SW) or H-2 mice (DBA/1). It is of interest to note that GAT did not stimulate antibody production of the IgM class by responder or non-responder strains either in vivo or in vitro. The GAT terpolymer differs, therefore, markedly in this respect from the branched polymers such as (T,G)-A--L which stimulate the synthesis of IgM antibodies in both responder and nonresponder strains. 

Ring enlargement of the natural product to its 15-membered aza-congener, followed by A-methylation, resulted in an antibiotic that has revolutionized the therapy of many infective diseases, in particular, those caused by highly resistant strains [23]. 

The protocol and data from a representative experiment using congenic-resistant mouse strains demonstrating the involvement of the H-2 gene complex in physiological lymphocyte interactions are shown in Figure 4.8. The DNP-primed B cells were derived from congenic-resistant BIO.A H-2 )... 

Many strains are resistant due to production of /1-lactamases. tThere are other congeners of ampicillin see the text. 

The carboxypenicillins, carbenicillin and ticarcillin, are active against some isolates of P. aeruginosa and certain indole-positive Proteus spp. that are resistant to ampicilhn and its congeners. They are ineffective against most strains of S. aureus. Enterococcus faecalis, Klebsiella, and... 

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