Cholera toxin genes: nucleotide sequence, deletion analysis and vaccine development

Nucleotide sequence and deletion analysis have been used to identify the regulatory and coding sequences comprising the cholera toxin operon (ctx). Incorporation of defined in vitro-generated ctx deletion mutations into Vibrio cholerae by in vivo genetic recombination produced strains which have practical value in cholera vaccine development.     

Effects of pyridoxal phosphate andl-dopapyridoxal phosphate on DOPA decarboxylase activity

Sommaire Les résultats obtenus démontrent une inhibition de l'activité de la DOPA decarboxylase par de haute concentration de PLP ou de faible concentration del-DOPA plus PLP. Ceci pourrait expliquer les observations cliniques et expérimentales précédentes démontrant que la pyridoxine antagonise l'effet del-DOPA utilisé dans le traitement de la maladie de Parkinson.     

Processing of a minimal antigenic peptide alters its interaction with MHC molecules

Before their recognition by T lymphocytes, protein antigens generally require processing by antigen-presenting cells. In a poorly understood series of events, the protein antigen is internalized, transformed and re-expressed on the surface of the antigen-presenting cell in association with gene products of the major histocompatibility complex (MHC). Small peptides derived from the native protein can be recognized in the absence of antigen processing, suggesting that processing involves proteolytic degradation. These peptides are thought to mimic the naturally produced peptide fragment. We describe here a synthetic peptide antigen of this type which does not require processing but which is nevertheless further processed by splenic antigen-presenting cells. Interestingly, this processing event specifically alters the interaction of the peptide with the class II MHC (Ia) molecule, markedly affecting both its potency as an antigen in vitro and its immunogenicity in vivo (IR gene control).     

The effects of diltiazem onPeriplaneta americana

Summary The effects of the calcium antagonist diltiazem on nerve and muscle in the cockroachPeriplaneta americana were examined. Diltiazem was observed to inhibit myogenic and glutamate-induced contractions of the visceral muscle while having either a potentiating, an inhibiting or a biphasic effect against proctolin-induced contractions. Against the isolated nervous system, diltiazem induced an increase in spontaneous discharge activity, followed by nerve block. Injection of diltiazem into cockroaches produced behavioral and toxic effects.Acknowledgments. The expert technical assistance of Miss Susan Auffarth is gratefully acknowledged. Bioresmethrin was provided by Dr. G.J.P. Singh. We would like to thank Nordic Laboratories for the gift of diltiazem.