It instructs participants to indicate how their thinking patterns change when they experience mild dysphoria. Questions are answered on a 0–4 Likert scale. The AGG and HOP subscales and the LEIDS-R total score were the primary outcome
measures for this study. The AGG and HOP reactivity subscales have been found to be strongly associated with irritability in depressed patients (Verhoeven et al. 2011) and with suicidality (Antypa et al. 2010; Verhoeven et al. 2011). The LEIDS-R total score is associated with serotonin vulnerability (response to tryptophan Inhibitors,research,lifescience,medical depletion) (Booij and Van der Does 2007) and with the interaction of serotonin transporter gene polymorphism and early-life events (Antypa and Van der Does 2010). Procedure All measures were obtained in a single session. All participants signed informed consent prior to participation and either received €10
Inhibitors,research,lifescience,medical or study BVD 523 credits. The research was approved by the Ethics Committee of the Institute of Psychology of Leiden University. Saliva samples were collected using Oragene Self-Collection Kits – DISC format (DNA Inhibitors,research,lifescience,medical Genotek Inc, Ottawa, Ontario, Canada); 200 μL of saliva was kept in lysis buffer (100 mmol/L NaCl, 10 mmol/L EDTA, 10 mmol/L Tris pH 8, 0.1 mg/mL proteinase K, and 0.5% w/v sodium dodecyl sulfate) until further processing. DNA isolation Genomic DNA was isolated from the samples using Inhibitors,research,lifescience,medical the Chemagic kit on a Chemagen Module I workstation (Chemagen Biopolymer-Technologie AG, Baesweiler, Germany). DNA concentrations were quantified by OD260 measurement and by agarose
gel electrophoresis. The average yield was approximately 4 μg of genomic DNA per sample. Polymerase chain reaction amplification The region of interest from the MAOA gene was amplified by triplex polymerase chain reaction (PCR) using the following primers: a 6-carboxyfluorescein-labeled Medium Resolution (MR) primer (5′-GGATAACAATTTCACACAGG-3′), forward primer (5′-ggataacaatttcacacaggACAGCCTGACCGTGGAGAAG-3′), and a reverse primer (5′-GGACCTGGGCAGTTGTGC-3′). Typical PCR reactions contained Inhibitors,research,lifescience,medical between 10 and 100 ng genomic DNA template, 1 pmol of forward primer, and 10 pmol of labeled MR and reverse primers. PCR was carried out in the presence next of 5% dimethyl sulfoxide with 0.3 U of BioThermAB polymerase (GeneCraft, Munster, Germany) in a total volume of 30 μL using the following cycling conditions: initial denaturation step of 5 min at 94°C, followed by 38 cycles of 30 sec 94°C, 30 sec 55°C, 30 sec 72°C, and a final extension step of 4 min 72°C. Analysis of PCR products One microliter of PCR product was mixed with LIZ-500 size standard and formamide and run on an AB 3100 genetic analyzer setup for genotyping with 50-cm capillaries. Results were analyzed using Genescan software version 3.7 (Applied Biosystems, Carlsbad, California) and alleles were scored visually.