Abstract-Treatment of low density lipoprotein (LDL) with degrading enzymes transforms the molecule to a moiety that is micromorphologically indistinguishable from lipoproteinaceous particles that are present in atherosclerotic plaques, and enzymatically modified LDL (E-LDL), but not oxidized LDL (ox-LDL), spontaneously activates the alternative complement pathway, as do lesion lipoprotein derivatives. Furthermore, because E-LDL is a potent inducer of macrophage foam cell formation, we propose that enzymatic degradation may be the key process that renders LDL atherogenic. In this article, we report the production of two murine monoclonal antibodies recognizing cryptic epitopes in human apolipoprotein B that become exposed after enzymatic attack on LDL. One antibody reacted with LDL after single treatment with trypsin, whereas recognition by the second antibody required combined treatment of LDL with trypsin and cholesterol esterase. In ELISAs, both antibodies reacted with E-LDL produced in vitro and with lesion complement activator derived from human atherosclerotic plaques, but they were unreactive with native LDL or ox-LDL. The antibodies stained E-LDL, but not native LDL or ox-LDL, that had been artificially injected into arterial vessel walls. With the use of these antibodies, we have demonstrated that early human atherosclerotic coronary lesions obtained at autopsy as well as lesions examined in freshly explanted hearts always contain extensive extracellular deposits of E-LDL. Terminal complement complexes, detected with a monoclonal antibody specific for a C5b-9 neoepitope, colocalized with E-LDL within the intima, which is compatible with the proposal that subendothelially deposited LDL is enzymatically transformed to a complement activator at the earliest stages in lesion development. (Arterioscler Thromb Vasc Biol. 1998;18:369-378.)

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Direct detection technologies for pathogenic microorganisms are emerging to be applied in the diagnosis of serious bloodstream infections and infections at sterile body sites, as well as for quality control measures prior to the release of sterile blood products and to ascertain microbial safety of food. Standard blood cultures as the current gold standard for detection of bacteraemia/sepsis and other culture-based microbiological identification procedures are comparatively slow and have limited sensitivity for fastidious or slow-growing microorganisms. Rapid nucleic acid-based technologies with PCR amplification or hybridisation probes for specific pathogens, broad-range bacterial or fungal assays, flow cytometry, as well as protein-based characterisation by mass spectrometry, aim at identification of pathogenic microorganisms within minutes to hours. Interpretation of direct detection of panbacterial or panfungal nucleic acids instead of living microorganisms in blood is complex, given the risk of contamination, the ubiquitous presence of bacterial and fungal DNA, and the lack of a gold standard. Since many of the infections at sterile sites, particularly sepsis, are medical emergencies requiring immediate therapeutic responses, rapid technologies could contribute to reduction of morbidity, mortality, and of the economic burden. This review summarises the currently available data on rapid non-culture-based technologies and outlines the potential clinical usefulness in infectious disease diagnosis.

Abstract-Complement activation occurs in temporal correlation with the subendothelial deposition of LDL during early atherogenesis, and complement also plays a pathogenetic role in promoting lesion progression. Two lesion components have been identified that may be responsible for complement activation. First, enzymatic degradation of LDL generates a derivative that can spontaneously activate complement, and enzymatically degraded LDL (E-LDL) has been detected in the lesions. Second, C-reactive protein (CRP) colocalizes with complement C5b-9, as evidenced by immunohistological studies of early atherosclerotic lesions, so the possibility exists that this acute phase protein also fulfills a complement-activating function. Here, we report that addition of LDL and CRP to human serum did not result in significant C3 turnover. Addition of E-LDL provoked complement activation, which was markedly enhanced by CRP.Binding of CRP to E-LDL was demonstrated by sucrose flotation experiments. Binding was Ca 2ϩ -dependent and inhibitable by phosphorylcholine, and the complement-activating property of E-LDL was destroyed by treatment with phospholipase C. These results indicated that CRP binds to phosphorylcholine groups that become exposed in enzymatically degraded LDL particles. Immunohistological studies complemented these findings in showing that CRP colocalizes with E-LDL in early human atherosclerotic lesions. Thus enzymatic, nonoxidative modification of tissue-deposited LDL can be expected to confer CRP-binding capacity onto the molecule. The ensuing enhancement of complement activation may be relevant to the development and progression of the atherosclerotic lesion. Key Words: atherogenesis Ⅲ corrective protein Ⅲ complement Ⅲ LDL C omplement and C-reactive protein (CRP) are emerging as 2 components that may play important roles in atherogenesis. Early studies indicated that activated complement components 1,2 and CRP 3,4 are present in atherosclerotic lesions, and the demonstration followed that in situ C5b-9 generation occurred in temporal correlation with lipid deposition. 5 The search for a complement-activating entity led to the isolation of an LDL derivative, termed lesion complement activator (LCA), that had the capacity to activate the alternative complement pathway. 6 We are considering that the high content of free cholesterol in the LCA particles is important because unesterified cholesterol activates complement. 7 Similar lipidic moieties were isolated in other laboratories, 8,9 although their capacity to activate complement was not tested. Furthermore, fused LDL particles micromorphologically similar to LCA were visualized in extracellular location by deep freeze-etch electronmicroscopy in arteries of cholesterol-fed rabbits. 10 Collectively, these studies indicated that tissue-deposited LDL is modified extracellularly to yield lipid droplets with a high content of free cholesterol that have intrinsic complement-activating capacity.Subsequently, it was shown that LDL, but not HDL or VLDL, could be transformed...