Acyclic analogue of lipid A stimulates TNF-alpha and arachidonate release via a unique LPS-signaling pathway.

LPS has been implicated in the pathogenesis of Gram-negative bacterial sepsis. Despite intensive efforts to define the LPS-signal transduction pathway, CD14 is the sole molecule clearly demonstrated to possess signaling capabilities. However, it remains unclear whether CD14 is the only LPS-signaling molecule expressed in phagocytes and how CD14-mediated signaling occurs. Compound SDZ 280.961 is a synthetic triacylated amino acid that structurally resembles the reducing sugar moiety of lipid A. SDZ 280.961 effectively stimulated TNF-alpha release from human PBMC. Co-incubation of PBMC with the specific LPS inhibitor Rhodobacter sphaeroides lipid A inhibited SDZ 280.961-mediated stimulation of TNF-alpha release, indicating that this analogue signals mononuclear cells via a LPS-activated signaling pathway. Induction of TNF-alpha release from mononuclear cells by SDZ 280.961 was strongly dependent on the presence of serum and was enabled by the presence of purified LPS-binding protein, characteristics of CD14-mediated signaling. In contrast, SDZ 280.961-mediated signaling was not inhibited by blocking anti-CD14 mAbs. A Chinese hamster ovary fibroblast line transfected with human CD14, which responds to LPS in a manner qualitatively similar to that of macrophage cell lines, failed to respond to SDZ 280.961. Taken together, these data suggest that the lipid A analogue SDZ 280.961 activates monocytes via a unique LPS-signal transduction pathway that appears to be independent of CD14.

Cremophor and Emulphor induced alterations of serum lipids and lipoprotein electrophoretic patterns of dogs.

The effects of Cremophor and Emulphor, two polyethoxylated castor oil vehicles, on serum lipids and lipoproteins electrophoretic patterns were examined in beagle dogs. The vehicles were given as daily intravenous (i.v.) infusions of 0.5 ml/kg. Flushing of the skin, edematous wrinkling of the skin above the eyes and shaking of the head were observed during or shortly after each infusion of either vehicle. Thrombocytopenia occurred in Emulphor-treated dogs but increased platelet counts occurred in Cremophor-treated dogs. The spleen, lymph nodes, livers and kidneys all had excessive amounts of lipid present. There were increased serum levels of triglycerides, lipids, cholesterol and lipoproteins. Electrophoresis of sera revealed decreased alpha-lipoprotein fraction and the appearance of a new, as yet unidentified, peak near the origin. The lipid and lipoprotein changes were more marked in dogs treated with Cremophor. It appears that daily infusion with either vehicle results in changes in serum lipids, lipoprotein patterns and tissue lipid content.

Chronobiologic fluctuation of cyclophosphamide induced urinary bladder damage in mice.

Cyclophosphamide is the most widely used alkylating agent in clinical medicine. The usefulness of this drug is often limited by its propensity to produce hemorrhagic cystitis. To be active cyclophosphamide must be metabolized by the mixed function oxidase system. It has been previously demonstrated that the oncolytic activity and host lethality of cyclophosphamide are dependent upon circadian fluctuations. When cyclophosphamide is administered i.p. to male mice there is a dose dependent increase in urinary bladder weight. Histopathologic examination of these bladders revealed hemorrhage, edema, inflammation and stretching of the epithelial lining. When administered i.p. at 4-h intervals throughout a 24-h time period, cyclophosphamide produced maximum bladder damage when administered at 0500 and 1700 and little or no damage to the bladder when administered at 0100 or 1300. These studies suggest that cyclophosphamide induced cystitis, a toxicity resulting from the metabolic production of acrolein, may also be dependent upon chronobiologic fluctuations.