Lipid-dispersed solution, production thereof and use in determining lipid levels

Abstract

.[.There is disclosed an aqueous dispersed solution as a standard solution for determining lipid levels, having a dispersion form and a particle size, which are similar to those of serum lipids. A lipid-dispersed solution is obtained by evaporating an organic solvent from a mixture prepared by adding cholesterol, a phospholipid, a bile acid or bile acid salt, and a neutral lipid and/or a cholesterol ester in the organic solvent, swelling the resultant thin-film like mixture with water or buffer heated at a temperature higher than a phase transition temperature of the lecithin, and then dispersing the solution by a physical shear force. There can be easily obtained a solution having a cholesterol concentration of about less than 1,000 mg/dl, which is extremely stable and can be stored for a long period of time..]. .Iadd.There is disclosed an aqueous dispersed solution as a standard solution for determining lipid levels, having a dispersion form and a particle size, which are similar to those of serum lipids. A lipid-dispersed solution is obtained by evaporating an organic solvent from a mixture prepared by adding cholesterol, a phospholipid, a bile acid or bile acid salt, and a neutral lipid and/or a cholesterol ester in the organic solvent, swelling the resultant thin-film like mixture with water or buffer heated at a temperature higher than a phase transition temperature of the lecithin, and then dispersing the solution by a physical shear force. These can be easily obtained a solution having a cholesterol concentration of about less than 1,000 mg/dl, which is extremely stable and can be stored for a long period of time. The lipid dispersed solution is used as a standard solution in calibrating a device for performing enzymatic lipid level determination, and the calibrated device is used to determine the lipid level (e.g. cholesterol) in a solution.

What is claimed is: 
     
       1. A process for producing a lipid-dispersed solution, which comprises the steps of dissolving a bile acid or a salt thereof and lipids in an organic solvent, wherein the lipids comprise a phospholipid, cholesterol and at least one member selected from the group consisting of a cholesterol ester and a neutral lipid, evaporating the organic solvent from the resultant solution at a temperature where the bile acid or the salt thereof and the lipids can be dissolved in the organic solvent, adding water or an aqueous solvent to the residual solid content, and applying a physical shear force. 
     
     
       2. The process for producing a lipid-dispersed solution in accordance with claim 1, wherein the step of applying the physical shear force is a step of irradiating with an ultrasonic wave. 
     
     
       3. The process for producing a lipid-dispersed solution in accordance with claim 1, wherein the step of evaporating the organic solvent is conducted under a deoxygenated atmosphere. 
     
     
       4. The process for producing a lipid-dispersed solution in accordance with claim 1, wherein a weight ratio of a sum of cholesterol and cholesterol ester to phospholipid is from 1:1 to 1:4, a weight ratio of bile acid salt to phospholipid is from 1:1 to 1:20, and a weight ratio of neutral lipid to phospholipid is from 1:10 to 1:5. .Iadd.5. A method for determination of lipid levels using a lipid-dispersed solution as a standard, comprising (1) providing a lipid-dispersed solution comprising a bile acid or a salt thereof; a phospholipid, cholesterol, and at least one member selected from the group consisting of a cholesterol ester and a neutral lipid as the lipids; and water or an aqueous solvent as a dispersing medium, said bile acid or salt thereof and said lipids being dispersed in said water or aqueous solvent, (2) calibrating a device for performing enzymatic lipid level determination using said lipid-dispersed solution as a standard solution, and (3) using said device to determine the lipid level of a solution..Iaddend..Iadd.6. The method according to claim 5, wherein the lipid levels to be determined are those of a bodily fluid..Iaddend..Iadd.7. The method according to claim 6, wherein the bodily fluid lipid level to be determined is a cholesterol level..Iaddend..Iadd.8. The method according to claim 5, wherein the phospholipid is lecithin and wherein a weight ratio of the sum of the cholesterol and cholesterol ester to the lecithin is from 1:1 to 1:4, a weight ratio of the bile acid salt to the lecithin is from 1:1 to 1:20, a weight ratio of the neutral lipid to the lecithin is from 1:10 to 1:15, and a concentration of the lecithin is not more than 1,000 
     
     
        mg/dl..Iaddend..Iadd.9.  The method of claim 5, wherein the concentration of said bile acid or salt thereof in said lipid-dispersed solution is from 50 to 1000 mg/dl..Iaddend.