Determination of endocannabinoids and endocannabinoid-like substances in human K3EDTA plasma - LC-MS/MS method validation and pre-analytical characteristics

The determination of endocannabinoids and endocannabinoid-like substances in biological human samples is a vibrant field of research with great significance due to postulated relevance of these substances in diseases such as Alzheimer's disease, multiple sclerosis, cancer and cardiovascular diseases. For a possible use as biomarker in early prediction or diagnosis of a disease as well as examination of a successful treatment, the valid determination of the analytes in common accessible human samples, such as plasma or serum, is of great importance. A method for the determination of arachidonoyl ethanolamide, oleoyl ethanolamide, palmitoyl ethanolamide, 1-arachidonoyl glycerol and 2-arachidonoyl glycerol in human K3EDTA plasma using liquid-liquid-extraction in combination with liquid chromatography-tandem-mass spectrometry has been developed and validated for the quantification of the aforementioned analytes. Particular emphasis was placed on the chromatographic separation of the isomers 1-arachidonoyl glycerol and 2-arachidonoyl glycerol, arachidonoyl ethanolamide and O-arachidonoyl ethanolamine (virodhamine) as well as oleoyl ethanolamide and vaccenic acid ethanolamide. During the validation process, increasing concentrations of 1-arachidonoyl glycerol and 2-arachidonoyl glycerol while storing plasma samples were observed. In-depth investigation of pre-analytical sample handling revealed rising concentrations for both analytes in plasma and for arachidonoyl ethanolamide, oleoyl ethanolamide and palmitoyl ethanolamide in whole blood, dependent on the period and temperature of storage. Prevention of the increase in concentration was not possible, raising the question whether human K3EDTA plasma is suitable for the determination of endocannabinoids and endocannabinoid-like substances. Especially the common practice to calculate the concentration of 2-arachidonoyl glycerol as sum of 1-arachidonoyl glycerol and 2-arachidonoyl glycerol is highly questionable because the concentrations of both analytes increase unequally while storing the plasma samples in the fridge.

[Presenile dementia in memory clinics--incidence rates and clinical features]

This study describes the clinical features of presenile dementia diagnosed in memory clinics. It further gives an estimate of the declared incidence for the German city of Munich and surrounding counties. Twelve memory clinics in Switzerland and Germany were considered, among them all of the four in Munich. A total of 267 patients with onset of illness under the age of 65 were included. Only 16 patients (6%) were younger than 50. Men and women were affected about equally often. The most common cause of dementia was Alzheimer's disease (67%), followed by frontotemporal degeneration (13.5%) and vascular (5.6%) dementia. The declared incidence was estimated at 8.3 new cases of dementia per year among 100,000 persons in the 50-64 age range, with an incidence rate of Alzheimer's disease at 6.3/100,000. It can be concluded that memory clinics fulfill an important function in the care of patients with presenile dementia, since they are highly utilized by younger patients in early stages of the illness.