Experiments were performed to determine whether the expression and/or repair of potentially lethal damage could be observed in mammalian cells exposed to hemataporphyrin derivative (HPD) photodynamic therapy (PDT). Photodynamic therapy was combined with posttreatment protocols known to inhibit the repair of potentially lethal damage in cells treated with X-rays, ultraviolet radiation, or alkyla...

ULLER in 1927 stated that the “partial sterility” of X-rayed males M of Drosophila wasdue,at least to an appreciable extent, to dominant lethal changes induced in the sperm. It was impossible, however, to determine whether the eggs were actually “fertilized.” In Drosophila the result would be the same; the eggs would fail to develop, whether dominant lethals were induced or the sperm were inact...

These studies are primarily concerned with recovery from sublethal actinomycin D or radiation damage as measured by joint lethality of the two treatments separated by an interval of 1 hr to 4 days. In mice given actinomycin D and challenged with radiation, the high mortality attributable to joint treatment decreased steadily between the 6-hr and the 3-day challenge. On the other hand, in mice g...

Clostridium sordellii lethal toxin (TcsL) is a large clostridial toxin (LCT) that glucosylates Ras, Rac, and Ral. TcsL differs from other LCTs because it modifies Ras, which does not cycle from cytosol to membrane. By using a suite of inhibitors, steps in cell entry by TcsL were dissected, and entry appears to be dependent on endosomal acidification. However, in contrast to TcdB, TcsL was subst...

Anthrax lethal toxin (LT) is a major virulence factor of Bacillus anthracis. LT challenge suppresses platelet counts and platelet function in mice, however, the mechanism responsible for thrombocytopenia remains unclear. LT inhibits cellular mitogen-activated protein kinases (MAPKs), which are vital pathways responsible for cell survival, differentiation, and maturation. One of the MAPKs, the M...

Six pregnant cows received, by injection into the rumen, 0.20 to 0.30 g urea/kg body-weight at 104 to 148 days of pregnancy, 0.35 g/kg at 124 to 169 days of pregnancy, 0.35 g/kg at 208 to 226 days of pregnancy and 0.30 g/kg at 256 to 273 days of pregnancy. The change in blood ammonia concentration was followed for approximately seven hours after dosing. Five cows survived until calving and gave...

Treatment of rabbits, rats, and mice with D-galactosamine increased their sensitivity to the lethal effects of lipopolysaccharide several thousand fold. The susceptibility of the animals was highest when the lipopolysaccharide was injected together with galactosamine and decreased successively when injection was carried out 1, 2, and 3 hr later. Sensitization was absent when the lipopolysacchar...