To prevent the development of atherosclerotic diseases, the Japanese guideline for prevention of atherosclerotic cardiovascular diseases (released from Japan Atherosclerosis Society in 2007) is clinically referred. In addition, the importance of evaluating not only the level but also the quality of low-density lipoprotein (LDL) has been advocated. Small dense LDL (sdLDL) is regarded as representation of the quality of LDL. With the Lipoprint^TM LDL subfraction system, utilizing non-denaturing polyacrylamide gel electrophoresis method which can evaluate several sdLDL-related parameters such as the area percentage of sdLDL, mean LDL particle size (mean LDL-PS), relative mobility in the form of the relative flotation rate (Rf), and LDL size-based phenotypic patterns. We attempted to assess the Japanese guideline for prevention of atherosclerotic cardiovascular diseases in terms of sdLDL-related parameters. We studied with 46 asymptomatic and cardiovascular disease-free dyslipidemic subjects (23 men, aged 30-58 years olds; 23 women, 31-58 years olds), who were within the primary prevention level. From the increased number of categories in the guideline, the following trends were observed; the smaller LDL-PS (p=0.002), the larger of area percentage of sdLDL (p=0.042), an increase in Rf (p=0.068), and an increase in the presence of pattern B (atherogenic phenotype) (p=0.031). These results suggested that, with the Lipoprint^TM system, the usage of Japanese guideline may clinically reflect well the sdLDL-related parameters, in particular the mean LDL-PS, the area percentage of sdLDL and the pattern B.

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We previously confirmed that crude streptolysin O (SLO) consists of heterogeneous components with different isoelectric points (pIs) and hemolytic efficiency, as determined by the slope of the titration curve. The two preparations of SLO having different pI distributions were further characterized in this research. The pIs of the major components of the two SLO preparations are around pH 6 (acidic) and 7.5 (neutral). Although the neutral SLO was shown to be more hydrophobic than the acidic SLO based on the behavior on hydrophobic interaction chromatography, the capacities of the two types to bind to erythrocytes did not differ. On the other hand, the neutral SLO destroyed liposomes to some extent, whereas the acidic SLO did not, even at concentrations of 100 HD₅₀ (50% hemolytic dose), suggesting that the mode of membrane damage by the two types of SLO are different. Furthermore, electron microscopic observation indicated that the acidic SLO preferably formed an irregular-shaped complex and semicircular pores on erythrocyte membranes, in contrast to the complete pore formation by the neutral SLO. Thus, we clarified that the two hemolytic forms of SLO have different pore formation efficiencies based on liposome membrane damage and electron micrographs of ghosts.

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