[Prostate cancer screening using prostate-specific antigen: The views of general and laboratory physicians]. / Cribado del cáncer de próstata mediante antígeno prostático específico: perspectiva del médico en atención primaria y en el laboratorio clínico.

INTRODUCTION: It is currently recommended to provide individualised information on benefit-risk balance and shared decision-making in prostate cancer screening using prostate-specific antigen (PSA). AIM: To determine the usual practice and the views of general and laboratory practitioners in the screening of prostate cancer using PSA. MATERIAL AND METHODS: A cross-sectional study based on a questionnaire and on PSA screening requests from Primary Health Care (PHC) in men older than 49 years with no prostatic symptoms. RESULTS: In 2015, PHC in Catalonia requested PSA on 15.2% of males. A total of 114 general practitioners and 227 laboratory practitioners participated in the questionnaire. The mean age of those who responded was 43 years with a mean of 17 years' experience, and included 64% women. According to general practitioners, 61% of PSA was performed at the patient's request. The uncertainty score when requesting PSA was 5 points for general practitioners and 5.7 for laboratory professionals. Interest in having clinical recommendations received 7.2 points in PHC, and 8.8 in the laboratory. Knowledge about the different clinical practice guidelines received was less than 5 points overall. CONCLUSIONS: General practitioners requested PSA screening in almost one-sixth of men over the age of 49 without prostate disease, often at the patient's request, and after informing them of the benefits and risks. PHC and laboratory physicians were interested in having recommendations and information, although they did not usually consult clinical practice guidelines immediately.

Comparison of two different methods for measurement of phenylalanine in dried blood spots.

Phenylketonuria is an inherited metabolic disorder caused by a defect in the hydroxylation of phenylalanine. Newborn screening is crucial for the diagnosis and treatment of this disease. A phenylalanine dehydrogenase-coupled enzymatic assay (Quantase) in microtiter plates for the screening of phenylketonuria was evaluated and compared with our routine method based on the modified fluorometric McCaman method. The test exhibited a linear calibration curve with a good slope as well as sufficient imprecision (< 10%), recovery (99.23+/-4.86%) and limit of detection (54.5 micromol/l). One hundred and ninety dried blood spots were analysed by this enzymatic method and compared with McCaman's. Although Quantase (Teknovas, Bilbao, Spain) showed a phenylalanine mean level in dried blood spot 18.2 micromol/l higher than that obtained with our routine method, the agreement between both techniques was considered acceptable.

Determination of N-acetylcysteine in human plasma by liquid chromatography coupled to tandem mass spectrometry.

An analytical method for the determination of total N-acetylcysteine in human plasma has been developed, validated and applied to the analysis of samples from a phase I clinical trial. The analytical method consists of plasma digestion with dithiothreitol in order to reduce all the oxidized forms of N-acetylcysteine, and extraction with ethyl acetate followed by determination of levels by an LC-MS-MS method. The intra- and inter-assay precision and accuracy of this technique were good and the limit of quantitation was 50 ng/ml of plasma. The concentration working range was established between 50 ng/ml and 1000 ng/ml. This method has been used in the analysis of approximately 800 human plasma samples from a clinical study with 24 volunteers; the precision of the quality controls was in the range 8.7 to 13.4% and the accuracy was in the range -5.9 to 8.5%, expressed as the RSD and the relative error, respectively.

Simultaneous determination of paracetamol and chlorpheniramine in human plasma by liquid chromatography-tandem mass spectrometry.

An analytical method for the determination of paracetamol and chlorpheniramine in human plasma has been developed, validated and applied to the analysis of samples from a phase I clinical trial. The analytical method consists in the extraction of paracetamol and chlorpheniramine with diethyl ether, followed by the determination of both drugs by an LC-MS-MS method, using 2-acetamidophenol as internal standard. The intra-assay and inter-assay precision and accuracy of this technique were good and the limit of quantitation was 0.5 microg/ml of plasma for paracetamol and 0.2 ng/ml for chlorpheniramine. The concentration working range was established between 0.5 microg/ml and 25 microg/ml for paracetamol and between 0.2 ng/ml and 50 ng/ml for chlorpheniramine. This method has been used for analyzing more than 1200 human plasma samples from a clinical study with 24 volunteers.