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Biomedical subjects

L Spero

Publications and source records attributed to L Spero.

At least 55 records · Page 3Linked to original sources
PubMed1971

Guanidination and nitroguanidination of staphylococcal enterotoxin B.

Guanidination of the free amino groups of staphylococcal enterotoxin B with 3,5-dimethyl-1-guanylpyrazole converted 31-32 of 33 epsilon-amino groups and 30% of the N-terminal residue. This product, although markedly reduced in solubility, suffered no gross change in conformation and retained full biological activity. A derivative prepared by reaction with O-methylisourea with only one lysyl residue unaltered lost most of its emetic activity. Nitroguanidination with 3,5-dimethyl-1-nitroguanylpyrazole converted up to 28 of the epsilon-amino groups and essentially all of the N-terminus. This material was greatly reduced in ability to produce emesis and like the O-methylisourea prepared guanidinated enterotoxin, gave only a line of partial identity in double diffusion. The loss of activity is attributed to unfolding and it is concluded that the free amino groups of enterotoxin B do not critically participate in either its antigenic determinants or its active center for emesis.

Affinity Labels↗
PubMed1970

The effects of calcium and magnesium on the response of intestine smooth muscle to drugs.

1. The sensitivity of the longitudinal muscle of the guinea-pig ileum to muscarinic drugs producing contraction depends on optimum concentrations of calcium and magnesium. It can also be reduced by changes in sodium concentration and osmolarity.2. The rubidium efflux response to these same drugs is insensitive to any of these changes in the external medium.3. Raised calcium or magnesium concentration has the effect of largely annulling the differences in structure-activity relationships of the two responses as they exist in optimal media.4. The effects are explained in terms of a labile coupling process between a single receptor and the contractile process compared with a stable coupling process of the efflux process.

Animals↗
PubMed1970

Molecular weight of type a botulinum toxin.

Clostridium botulinum type A does not produce a 12,000 molecular weight toxin. The reported isolation of such a material by Gerwing et al. could not be confirmed.

Journal Article↗