Expression Of Biological Activity Research Articles

Mitogenic activities of lipid A and liposome-associated lipid A: effects of epitope density.

Among eight purified lipid A fractions, there was heterogeneity of mitogenic activity, but the relative activity could not be predicted by limulus amebocyte lysate assay. Analysis of mitogenic activity after the incorporation of lipid A into liposomes demonstrated that epitope density of lipid A was a crucial factor that strongly modulated expression of lipid A. The results suggest that lipid A hydrophobic groups are responsible for mitogenic activity and that the surface accessibility of lipid A hydrophobic groups in membranes may be influenced by epitope density. The data are compared with previous results derived from parallel studies on limulus amebocytes. Both approaches lead to the conclusion that the activities of purified lipid A fractions are heterogeneous and that epitope density is critically important for the expression of biologic activity of membrane-associated lipid A.

Complement-independent activation of the fifth component (C5) of human complement: limited trypsin digestion resulting in the expression of biological activity.

Complement-independent activation of the fifth component (C5) of human complement: limited trypsin digestion resulting in the expression of biological activity.

Effects of cold-restraint stress on rat gastric and hepatic glutathione: A potential determinant of response to chemical carcinogens

Stressor-induced decreases in glutathione (GSH) concentrations were demonstrated in the liver and the gastric mucosa. Either food deprivation and/or the time of day the stressor was administered could affect the extent of stressor-induced decreases in GSH. The system described may be useful for further exploration of potential stressor-induced alterations in susceptibility to chemical carcinogens and/or other toxins whose expression of biological activity may be dependent upon GSH.

Evaluation of human follicle-stimulating hormone preparations.

SUMMARY A procedure for the purification of human pituitary follicle-stimulating hormone (FSH) is outlined. Various methods of protein determination were applied to the preparation (CP 150), and the results obtained compared with those of amino acid analysis. The composition of CP 150 with respect to amino acid and carbohydrate components is reported, and is suggested as the most suitable basis for expression of biological activity and stability. CP 150 sedimented as a single boundary with S20,w = 2·8s. The composition of various reported FSH preparations including CP 150 are compared, and attention is drawn to some striking similarities.