This review focuses on the application of matrix assisted laser desorption/ionization (MALDI) mass spectrometry to the characterization of molecules in the low mass range (<1500 Da). Despite its reputation to the contrary, MALDI is a powerful technique to provide both qualitative and quantitative determination of low molecular weight compounds. Several approaches to minimize interference via sample preparation and matrix selection are discussed, as well as coupling of MALDI to liquid and planar chromatographic techniques to extend its range of applicability.

Background The Interpersonal Theory of Suicide states that to make a serious or lethal suicide attempt a person must experience reductions in fear and pain sensitivity sufficient to overcome self preservation reflexes (i.e., the acquired capability for suicide). The purpose of the current study was to examine the fearlessness component of the acquired capability for suicide using self-report assessment instruments and an objective measure of aversion (the affectively modulated startle reflex task). Methods Depressed suicide ideators (n = 15), depressed suicide attempters (n = 15), and a group of control participants (n = 14) were compared on their self-report of acquired capability and painful and provocative life events and completed the affectively modulated startle reflex task. This task compared electromyography recordings of participants’ eye-blink response to a startle probe while viewing pictures of varying hedonic valence (neutral, positive, negative, and suicide-related). Results Suicide attempters reported the highest levels of fearlessness and pain insensitivity and a greater history of painful and provocative life events. While no group differences were found on the psychophysiology data, participants reacted to suicide-related images with less aversion compared to neutral images with no differences between suicide-related and positive images. Conclusions Self-reported fearlessness and pain insensitivity can differentiate suicide attempters and suicide ideators. Results suggest that one’s self-perception (i.e., cognitions regarding fear and pain tolerance) are more functionally related to suicide attempts than psychophysiological reactivity to suicide-related stimuli.

No abstract

Discussion : Among women who quit smoking during pregnancy, a worsening of depressive and stress symptoms over 12 weeks postpartum was associated with an increased risk of smoking by 24 weeks. IntroductionApproximately one third of female smokers quit once they learn that they are pregnant ( Fingerhut, Kleinman, & Kendrick, 1990 ;Floyd, Rimer, Giovino, Mullen, & Sullivan, 1993 ;LeClere & Wilson, 1997 ;Severson, Andrews, Lichtenstein, Wall, & Zoref, 1995 ), but up to two thirds of women who stop smoking during pregnancy relapse within 6 months after delivery ( Colman & Joyce, 2003 ;Fingerhut et al., 1990 ;Martin et al., 2008 ;McBride & Pirie, 1990 ;McBride, Pirie, & Curry, 1992 ;Ratner, Johnson, Bottorff, Dahinten, & Hall, 2000 ). Women who remain tobacco abstinent after delivery experience health benefi ts that include protection of infants from secondhand smoke exposure, lower risk of poor pregnancy outcomes in subsequent pregnancies, and decreased personal risk of tobacco-related health problems ( Mullen, 2004 ). To increase the proportion of women who maintain tobacco abstinence after delivery, it is necessary to understand the modifi able factors associated with postpartum relapse to smoking.In the general population, depression, anxiety, and stress are more common among smokers than nonsmokers; these factors are barriers to smoking cessation and triggers for relapse AbstractIntroduction : The aim of this prospective repeated measures, mixed-methods observational study was to assess whether depressive, anxiety, and stress symptoms are associated with postpartum relapse to smoking.Methods : A total of 65 women who smoked prior to pregnancy and had not smoked during the last month of pregnancy were recruited at delivery and followed for 24 weeks. Surveys administered at baseline and at 2, 6, 12, and 24 weeks postpartum assessed smoking status and symptoms of depression (Beck Depression Inventory [BDI]), anxiety (Beck Anxiety Inventory [BAI]), and stress (Perceived Stress Scale [PSS]). In-depth interviews were conducted with women who reported smoking.Results : Although 92% of the participants reported a strong desire to stay quit, 47% resumed smoking by 24 weeks postpartum. Baseline factors associated with smoking at 24 weeks were having had a prior delivery, not being happy about the pregnancy, undergoing counseling for depression or anxiety during pregnancy, and ever having struggled with depression ( p < .05). In a repeated measures regression model, the slope of BDI scores from baseline to the 12-week follow-up differed between nonsmokers and smokers ( − 0.12 vs. +0.11 units/week, p = .03). The slope of PSS scores also differed between nonsmokers and smokers ( − 0.05 vs. +0.08 units/week, p = .04). In qualitative interviews, most women who relapsed attributed their relapse and continued smoking to negative emotions.

A method is presented that describes a reliable and practical procedure for quantitation of an analyte present at relatively high background levels in blank (untreated) biological matrixes. Using a "surrogate analyte" approach, an endogenous analyte was quantitated in a variety of biological matrixes containing both very low (<10 ng/mL) and high (>2000 ng/mL) background levels of the desired analyte. This quantitative "surrogate analyte" approach was applied during the development of an HPLC/MS method for alpha-ketoisocaproic acid (KIC), which was identified as a potential biomarker for branched chain amino acid transferase inhibitor activity. Using deuterium-labeled KIC (d(3)) as a surrogate analyte, not an internal standard, to generate the calibration curve, the concentration of KIC in biofluid could be back-calculated based on the regression equation and response factor of KIC to KIC-d(3). In particular, this approach made it possible to prepare standards in control biofluid such as plasma, which greatly facilitated the process of method development. For the validated method, a linear range of 10-5000 ng/mL for KIC-d(3) was observed. Intraday and interday experimental accuracy, calculated as percent error, were in the range of < or =10% for KIC-d(3). This method is simple, rapid, and reliable for the quantitation of KIC in plasma, brain homogenate, cerebrospinal fluid, and other biological samples from discovery and pharmacological studies.