Studies of low density lipoprotein molecular weight in human beings with coronary artery disease

Low density lipoprotein molecular weight (LDL MW) correlates positively with coronary artery disease in cholesterol-fed nonhuman primates. To evaluate this in human beings with coronary artery disease (CAD) we measured LDL MW in 93 volunteers undergoing coronary angiography (47 controls and 46 CAD patients). LDL MW of CAD patients was less than that of controls (patients, 2.79 +/- 0.17 g/mumol; controls, 2.93 +/- 0.19 g/mumol; P less than 0.001). However, LDL MW decreased as plasma triglyceride increased and concentrations of triglyceride were greater in CAD patients than in controls. Since decreased LDL MW is likely to result, in part, from increased plasma triglyceride concentrations, we attempted to determine the effect of triglyceride on the relation of LDL MW to CAD in this study. After covariance adjustment for triglyceride, there was no LDL MW difference between CAD patients and controls. Because LDL heterogeneity has been identified in other studies and was apparent on inspection of agarose column profiles of LDL of these volunteers, we sought differences in the profiles that might distinguish coronary disease cases from controls. No differences could be found. In addition, we used density gradient ultracentrifugation to characterize LDL in more detail in a subset of volunteers who had a wide range of plasma triglyceride concentrations (50 mg/dl to 900 mg/dl). LDL mean hydrated density was inversely related to LDL MW and increased as triglyceride increased. The increase in peak density was reflected in an increase in percent of total protein in LDL found to have d greater than 1.045 g/ml and a decrease in protein in LDL of d 1.035-1.040 g/ml. These interrelationships were not apparently influenced by coronary artery status.     

Stimulation by heme of steryl ester synthase and aerobic sterol exclusion in the yeast Saccharomyces cerevisiae.

Saccharomyces cerevisiae sterol and heme auxotrophs were used to elucidate a role for hemes in sterol esterification. Steryl ester synthase (SES) activity was stimulated on average fourfold in cells supplemented with 50 micrograms/ml delta-aminolevulinic acid (ALA). This stimulation was not dependent on ALA per se, but on the ability of this precursor to effect heme competency. The addition of ALA stimulated SES activity of yeast on either fermentative or respiratory carbon sources. The elevation of SES activity was independent of intracellular free sterol, unsaturated fatty acid, or methionine levels. SES activity increases as the cells enter stationary phase, and this increase is enhanced by heme competency. SES was directly inhibited by the hypocholesterolemic drug lovastatin (mevinolin). The inhibition of SES activity by lovastatin was enhanced in heme-competent cells.     

Control of matrix metalloproteinase catalytic activity

As their name implies, MMPs were first described as proteases that degrade extracellular matrix proteins, such as collagens, elastin, proteoglycans, and laminins. However, studies of MMP function in vivo have revealed that these proteinases act on a variety of extracellular protein substrates, often to activate latent forms of effector proteins, such as antimicrobial peptides and cytokines, or to alter protein function, such as shedding of cell-surface proteins. Because their substrates are diverse, MMPs are involved in variety of homeostatic functions, such as bone remodeling, wound healing, and several aspects of immunity. However, MMPs are also involved in a number of pathological processes, such as tumor progression, fibrosis, chronic inflammation, tissue destruction, and more. A key step in regulating MMP proteolysis is the conversion of the zymogen into an active proteinase. Several proMMPs are activated in the secretion pathway by furin proprotein convertases, but for most the activation mechanisms are largely not known. In this review, we discuss both authentic and potential mechanisms of proMMP activation.     

Incorporation of Host Complement Regulatory Proteins into Newcastle Disease Virus Enhances Complement Evasion

Newcastle disease virus (NDV), an avian paramyxovirus, is inherently tumor selective and is currently being considered as a clinical oncolytic virus and vaccine vector. In this study, we analyzed the effect of complement on the neutralization of NDV purified from embryonated chicken eggs, a common source for virus production. Fresh normal human serum (NHS) neutralized NDV by multiple pathways of complement activation, independent of neutralizing antibodies. Neutralization was associated with C3 deposition and the activation of C2, C3, C4, and C5 components. Interestingly, NDV grown in mammalian cell lines was resistant to complement neutralization by NHS. To confirm whether the incorporation of regulators of complement activity (RCA) into the viral envelope afforded complement resistance, we grew NDV in CHO cells stably transfected with CD46 or HeLa cells, which strongly express CD46 and CD55. NDV grown in RCA-expressing cells was resistant to complement by incorporating CD46 and CD55 on virions. Mammalian CD46 and CD55 molecules on virions exhibited homologous restriction, since chicken sera devoid of neutralizing antibodies to NDV were able to effectively neutralize these virions. The incorporation of chicken RCA into NDV produced in embryonated eggs similarly provided species specificity toward chicken sera.