Polyamine oxidase in human retroplacental serum inhibits the growth of Plasmodium falciparum

Human retroplacental serum (RPS) containing polyamine oxidase inhibited the growth of the Camp strain of Plasmodium falciparum in vitro as assayed by the parasite's decreased incorporation of 3H-hypoxanthine. Inhibition was dose-dependent on the concentrations of serum polyamine oxidase and added polyamines. Almost complete inhibition was seen in 96-hr asynchronous cultures containing 10% RPS and in those containing 1.2% RPS plus 50 microM polyamine. Subtle morphologic changes in mature stages and decreased numbers of new rings were associated with inhibition seen in 19-hr synchronous cultures initiated at the trophozoite stage. These incubation times were longer than in previous reports showing inhibition of malaria parasites by bovine polyamine oxidase but not by human polyamine oxidase. Macrophages contain polyamine oxidase, the reaction products of which are known to be similar to those of RPS polyamine oxidase but different from those of bovine polyamine oxidase. It remains to be determined whether human polyamine oxidase, acting upon ubiquitous polyamines, contributes to host defenses against malaria.

Isolation of cold-sensitive mutants of measles virus from persistently infected murine neuroblastoma cells

Clone NS20Y of the mouse neuroblastoma C1300 was infected with wild-type Edmonston measles virus, and, after a transition to a carrier culture, became persistently infected. Persistently infected clones were derived and characterized morphologically by the appearance of multinucleate giant cells and nucleocapsid matrices in cytoplasm and nucleus, but very few budding virus particles. Antimeasles antibodies markedly suppressed the expression of viral antigens and giant cells, and the effect was totally reversible. When the cells were cultured at 33 degrees C, the number of giant cells began to diminish and ultimately disappeared; in contrast, when cultured at 39 degrees C, the cultures invariably lysed. Yields at 33 degrees C were ca. 2 logs lower than those at 39 degrees C. Cells cultured at 33 degrees C produced relatively high levels of interferon, whereas those at 39 degrees C produced little or no interferon. When the persistently infected cultures were exposed to anti-interferon alpha/beta serum at a nonpermissive temperature, there was a marked increase in multinucleate cells, suggesting that maintenance of the persistence state and its regulation by temperature may be related to the production of interferon. Viral isolates from cells cultured at 39 degrees C were obtained, and 90% of viral clones were found to be cold sensitive. Complementation studies with different viral clones indicated that the cold-sensitive defect was probably associated with the same genetic function. Western blot analysis of the persistently infected cells indicated a significant diminution and expression of all measles-specific proteins at a nonpermissive temperature. Infection of NS20Y neuroblastoma cells with the cold-sensitive virus isolates resulted in the development of an immediate persistent infection, whereas infection of Vero or HeLa cells resulted in a characteristic lytic infection, suggesting that the cold-sensitive mutants may be selected or adapted for persistent infection in cells of neural origin.

Hageman factor activation and tight junction disruption in mice challenged with attenuated endotoxin

Endotoxin treated with chromium chloride is less toxic to mice than the parent molecule, but can disrupt intestinal permeability barriers and has an enhanced ability to activate Hageman factor.

Possible association of granulocyte mobilization to the peritoneal cavity with ZnCl2-induced protection against endotoxin

We have attempted to determine which components of the inflammatory response are responsible for ZnCl2-induced retention of endotoxin in the peritoneal cavity and enhancement of survival following challange with the toxin. ZnCl2 injected intraperitoneally into mice caused accumulation of granulocytes in the peritoneal cavity, but these cells were apparently not responsible for the trapping process. This contention in supported by our observation that reduction of hepatosplenic uptake of 51CR-labeled endotonxin was similar in unirradiated mice and in mice made by irradiation (1000 rad 60 Co) 1 rad = 10 (-2) J/kg). Hepatosplenic uptake was also depressed when untreated mice were injected with endotoxin suspended in cell-free plasma. Furthermore, zinc did not protect irradiated mice challanged with endotoxin, although it enhanced survival in urirradiated animals. Lack of protection in irradiated mice may be due to a deficiency in the cellular response in the peritoneal cavity.

Antibiotic decontamination of the dog and its consequences

An isolation-decontamination regimen was developed which effectively reduced the numbers of resident flora of the dog. Bacterial counts in four dogs before treatment were 3.8 X 10(9) per gram of feces; no organisms were detectable in these same dogs after treatment, however, the intestinal flora had returned to slightly above normal levels 1 week after treatment. Decontamination was accomplished in a laminar air flow system designed to minimize the area that had to be under controlled conditions. By determining the antibiotic sensitivities of 67 isolated organisms representing eight species or groups of bacteria recovered from the four dogs, a standardized antibiotic regimen was developed consisting of bacitracin and neomycin administered as a dry powder in the food. The decontamination treatment apparently did not affect host metabolism because no alterations in serum levels of urea nitrogen, glucose, phosphate, total protein, chloride, sodium, potassium, serum glutamic oxalacetic transaminase, or serum glutamic pyruvic transaminase were found in the antibiotic-treated dogs. The decontamination process did, however, reduce normal granulopoietic stimulation.