Lipidology is the scientific study of lipids. Lipidology is the scientific study of lipids. Compared to other biomedical fields, lipidology was originally less popular since the constant handling of oils, smears, and greases was unappealing and separation was difficult. The field became more popular following the advent of chromatography which allowed lipids to be isolated and analyzed. The field was further popularized following the cytologic application of the electron microscope which found that many metabolic pathways take place on the cell membrane, whose properties are strongly influenced by its lipid composition. The Framingham Heart Study and other epidemiological studies have found a correlation between lipoproteins and cardiovascular disease. A class of lipids known as phospholipids help make up what is known as lipoproteins, and a type of lipoprotein is called high density lipoprotein (HDL). A high concentration of high density lipoproteins-cholesterols (HDL-C) have what is known as a vasoprotective effect on the body, a finding that correlates with an enhanced cardiovascular effect. There is also a correlation between those with diseases such as chronic kidney disease, coronary artery disease, or diabetes mellitus and the possibility of low vasoprotective effect from HDL.