Patent ID: 8278118

Claim:
A method for the fractionation of cell lysates, tissue lysates, cell homogenates, or tissue homogenates contained in a sample into separate particles with different densities by centrifugal sedimentation in a centrifuge sedimentation chamber containing the sample suspended in a volume of an extracting medium of specific density such that said particles having a density less than or equal to said extracting medium will not sediment and said particles having a density greater than said extracting medium will move through the volume of the extracting medium, said method comprising the steps of: (a) delivering said sample to be analyzed as a suspension in said volume of an extracting medium of specific density to said sedimentation chamber; (b) spinning said centrifuge sedimentation chamber at the axis of rotation for a period of time between about 1 minute to about 2 hours at a centrifugal force between about 500 g to about 200,000 g; (c) allowing said particles having a density greater than said extracting medium of specific density to form a deposit on the inside wall of said sedimentation chamber; (d) removing the extracting medium from the sedimentation chamber to recover said particles having a density less than or equal to said extracting medium of specific density; (e) delivering to said sedimentation chamber a liquid volume of an extracting medium of a specific density that is different from that used in the extracting medium of step (c); (f) resuspending in said sedimentation chamber the deposited particles from step (c) by agitation with the extracting medium of step (e); (g) repeating steps (b)-(f) to isolate at least two fractions of different densities from said sample; (h) repeating steps (a)-(g) with a second sample to isolate at least two fractions of said second sample where the second sample fractions are the same densities as the fractions in step (g); (i) quantitatively analyzing one or more biomarkers within each of said fractions from steps (g) and (h) from each sample to obtain a value; (j) pairing the value for each fraction within a sample to the value for every other fraction within the sample to determine ratios between all pairs of fractions from step (g) and all pairs of fractions from step (h); and (k) comparing said ratios obtained from step (j) for the group of fractions from step (g) to said ratios obtained from step (j) for the group of fractions from step (h) to determine whether there is a statistical difference between said ratios.