No abstract

Biomarkers, 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 , are important indicators of the vitamin D general status and are monitored in several pathophysiological disorders, such as osteoporosis, diabetes, heart disease, etc. A novel ultra-HPLC with MS/MS methodology for the analysis of 25-hydroxyvitamin D derivatives coupled with a very simple and highly rapid sample preparation step was developed. Analytical parameters obtained showed linearity (R(2) ) above 0.999 for both vitamins with accuracies between 95.8 and 102%. The LODs were as low as 0.22 and 0.67 nmol/L for 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 , respectively. Intra-assay precision (%RSD) was lower than 4.5%, and inter-assay precision (%RSD) was lower than 6.5%. The feasibility of the developed methodology to be applied in clinical routine analysis has been proved by its application in blood samples from non-agenarian patients, patients with familial hypercholesterolemia and patients suffering from age-related macular degeneration.

A complete change in lifestyle, a strict diet and intensive combined pharmacotherapy (HMG CoA reductase inhibitors are the most important components) are necessary for patients with familial hypercholesterolemia (FH) and provide excellent results in most patients. Unfortunately, these measures are not sufficient for all patients (1-6). Homozygous FH patients usually fail to show any response to pharmacotherapy. LDL-apheresis has become the standard treatment for individuals homozygous for FH (7-9). In homozygous FH, statins provide a range of responses, decreasing the plasma LDL anywhere from 0% to 48%, with an average of approximately 15% for receptor-negative individuals and approximately 26% for receptor-defective individuals (5). LDL-apheresis could be offered to treat symptomatic coronary heart disease in individuals who are heterozygous FH and whose LDL remains high (.160 mg/ dL, 4.2 mmol/L) or decreases by ,40% in response to maximal medical treatment (1).Term LDL-apheresis was originally used in 1981 by Stoffel et al. (10) as an immunoadsorption elimination extracorporeal method (10). Nowadays, "LDL-apheresis" or "lipoprotein apheresis" is used for all types of extracorporeal eliminations of cholesterol. In our study we used a modification of the Stoffel and Borberg LDLapheresis-immunoadsorption method and also double filtration plasmapheresis (the primary filter is replaced by a centrifugal separator), which additionally eliminates fibrinogen and has an influence on rheological properties. For our study we will use for the first mentioned method the term "LDL-apheresis" and for the second mentioned method the term "rheohaemapheresis."LDL-apheresis is an invasive and relatively expensive but safe procedure (11, 12); it decreases cholesterol radically but it is also troubling to the patient's standard AS CR v.v.i., Olomouc, Czech Republic (Received June 26, 2014) Summary Lipid apheresis (extracorporeal lipoprotein elimination) is administered to patients with familial hypercholesterolemia who fail to respond to standard therapy. The nature of the treatment process raises the suspicion that it decreases not only cholesterol but also antioxidants. A group of 12 patients (average age 47617 y, 4 homozygous and 8 heterozygous individuals) with familial hypercholesterolemia treated by LDL-apheresis or rheohaemapheresis for 3-12 y was included in the study. In addition to cholesterol and triacylglycerol levels, vitamin E and vitamin A and also other markers of antioxidant activity were investigated. Nevertheless, the most important determined parameter was the vitamin E/cholesterol ratio in serum and lipoproteins. The results indicate that both extracorporeal elimination methods are effective and suitable ways to treat severe familial hypercholesterolemia, as the LDL fraction of cholesterol decreased by approximately 77% and 66% following LDL-apheresis and rheohaemapheresis, respectively. In addition, the serum vitamin E decreased by 54% and 57% and the decrease of the serum vitamin A was approximately 20%...