Peptidylarginine deiminase type 4, anticitrullinated peptide antibodies, and rheumatoid arthritis.

Anticitrullinated peptide antibodies seem to be one of the most clinically reliable serologic markers for rheumatoid arthritis (RA). A genetic approach revealed that one of the citrullinating enzymes has a RA-susceptible variant. Peptidyl citrullination alters the chemical character of peptides and, subsequently, their antigenicity as well.

Destruxin B, a specific and readily reversible inhibitor of vacuolar-type H(+)-translocating ATPase.

Destruxin B, a peptide antibiotic, inhibits vacuolar-type ATPase (V-ATPase) specifically and dose-dependently among ATPases examined. Acidification of intracellular organelles is also blocked by destruxin B at comparable concentrations when assessed by accumulation of acridine orange. The inhibitory activity of destruxin B is weaker than that of bafilomycin A1 and folimycin, well known macrolide inhibitors of V-ATPase, when compared at the same molar concentration.

Homologous recombination at c-fyn locus of mouse embryonic stem cells with use of diphtheria toxin A-fragment gene in negative selection.

In attempting to produce a mutant mouse with embryonic stem cells, the critical step is the efficient isolation of homologous recombinants; the frequency of the homologous recombination is usually low and the potency of the cells to differentiate into germ cells is unstable in culture. Here, we report an efficacious method for such isolation in which the diphtheria toxin A-fragment gene is used to negatively select nonhomologous recombinants. In contrast to the use of the herpes simplex virus thymidine kinase gene, the selection can be made singly by the neomycin analog G418 without using a drug such as ganciclovir, a nucleoside analog.