Flotation rate, lipoprotein concentration

Experimental data thus far accumulated indicate that within the range 0-4,000 mg. % of lipoprotein, with flotation rates S/ 3-10, the value of k is 6,210 (mg. %) b This value was obtained by experimental measurement of flotation rate as a function of concentration. It is evident that the assumption of linear variation in flotation rate with concentration is not valid as the lipoprotein concentration becomes extremely high. For a more critical analysis it would be necessary to use the actual F vs. c function over the entire range of lipoprotein concentration involved. 

One of the capabilities of the present methodology is the evaluation of potential relationships that may eidst between flotation rate of the major component of the Sf 0-12 lipoprotein class and the concentration of each narrow segment of both the high- and low-density lipoprotein spectra. Such a relationship might indicate, for instance, that a certain lipoprotein proflle is associated with either a slow or fast Sf° rate of the major 0-12 class. In order to visualize such relationships, we have plotted in Fig. 8 the correlation coeflBcients observed between these variables in both our male and female populations. 

In many sera there exists either a host of lipoprotein species which give rise to closely spaced boundaries or an actual continuum of lipoproteins with respect to flotation rate. This complicates the problem of the determination of the concentration of individual lipoprotein species. Figure 6 is a reproduction of the analytical ultracentrifuge film record of a human lipoprotein concentrate (Preparative Type 1), showing a broad deflection... 

Fig. 7. Schematic interpretation of the broad deflection observed in the analysis of a continuum of lipoproteins (see text). The observed pattern is interpreted as arising from the summation of overlapping deflections due to many individually migrating lipoprotein boundaries. Concentrations in such patterns are measured between chosen flotation rate limits (designated here as limit A and limit B).

The choice of flotation rate limits between which the sum of lipoprotein concentrations is measured is at the discretion of the investigator. The... 

In lipoprotein analysis of the continuum type we have made the approximation that a particular lipoprotein band, e. g., the Sf 0-12 lipoprotein band, can be considered as a discrete component and assigned a flotation rate, which is determined by the position on the x axis of the integral curve that divides the total concentration for that band in half. This position is referred to as the mid-area position. The flotation rates corresponding to such mid-area positions (by use of the Svedbeig identity) are used in applications of the Johnston-Ogston correction. 

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