Generalization of fear in post-traumatic stress disorder

Overgeneralization (i.e., the transfer of fear to stimuli not related to an aversive event) is part of alterations in associative fear learning in mental disorders. In the present experimental study, we investigated whether this holds true for post-traumatic stress disorder (PTSD) related to childhood abuse. We expected that fear generalization under experimental conditions reflects generalization of aversive stimuli to different social domains in real life. Sixty-four women with PTSD after childhood abuse and 30 healthy participants (HC) underwent a differential fear conditioning and generalization paradigm. Online risk ratings, reaction time, and fear-potentiated startle served as dependent variables. Based on the subjectively assessed generalization of triggered intrusions across different domains of life, PTSD participants were split into two groups reporting low (low-GEN) and high (high-GEN) generalization. PTSD patients reported a higher expectation of an aversive event. During fear conditioning, they assessed the risk of danger related to a safety cue slower and showed a blunted fear-potentiated startle toward the danger cue. During generalization testing, reaction time increased in the high-GEN patients and decreased in the HC group with increasing similarity of a stimulus with the conditioned safety cue. Alterations of fear learning in PTSD suggest impaired defensive responses in case of a high threat probability. Moreover, our findings bridge the gap between the generalization of aversive cues during everyday life and laboratory-based experimental parameters: impairments in the processing of cues signaling safety generalize particularly in those patients who report a spreading of PTSD symptoms across different domains of everyday life.

Using Indirect Measurement Tasks to Assess the Self–Concept of Personality: A Systematic Review and Meta–Analyses

This systematic review presents the current state of research investigating the implicit self–concept of personality. First, we present results on meta–analyses estimating internal consistency, reliability coefficients, the implicit–explicit consistency and the single association predictive effect of implicit self–concept of personality measures. To do this, studies were aggregated over personality domains. Second, for each of the Five Factor personality domains, different aspects of construct validity and predictive validity are reviewed in a narrative way. Results show that implicit self–concept of personality measures are reliable, and there is evidence for the construct and predictive validity of these implicit measures, especially in the extraversion and agreeableness domains of personality. However, it must be kept in mind that clear evidence for publication bias was found for studies examining the single association predictive pattern. Finally, this systematic review identifies some achievable improvements that are needed in future research. Large cross–lab efforts are important in this respect. Moreover, the implicit self–concept of personality field must move from an ‘ad hoc’ to a ‘validation’ approach in developing new indirect measurement tasks. By adopting these research objectives, the information processing account of personality will increase its potential to become integrated into mainstream personality theory and research. Copyright © 2017 European Association of Personality Psychology

The paediatric liver transplantation program at the Université catholique de Louvain

The Paediatric Liver Transplant Program at Saint-Luc University Clinics constitutes a substantial single centre experience, including 667 transplantations performed between March 1984 and April 2003, and the history of this program reflects the tremendous progress in this field since twenty years. Liver transplantation in children constitutes a considerable undertaking and its results depend on multiple, intermingled risk factors. An analysis of the respective impact of several surgical and immunological parameters on patient/graft outcome and allograft rejection after paediatric liver transplantation showed a significant learning curve effect as well as the respective impact of pre-transplant diagnosis on survival and of primary immunosuppression on the rejection incidence. The introduction of living related liver transplantation in 1993 not only permitted to provide access to liver replacement in as many as 74% more candidate recipients, but also resulted in better graft survival and reduced retransplantation rate. The results of a recent pilot study suggest that steroid avoidance is not harmful, and could even be beneficial for paediatric liver recipients, particularly regarding growth, and that combining tacrolimus with basiliximab (anti-CD25 chimeric monoclonal antibody) for steroid substitution appears to constitute a safe alternative in this context. The long-term issues represent the main future challenges in the field, including the possibility of a full rehabilitation through immunosuppression withdrawal and tolerance induction, the development of adolescence transplant medicine, and the risk of early atherogenesis in the adulthood.

Sequential and simultaneous feature positive discriminations: occasion setting and configural learning in human Pavlovian conditioning

Using a conditioned suppression preparation, the authors investigated sequential (X --> A+/A-) versus simultaneous (XA+/A-) feature positive (FP) discrimination learning in humans. The sequential discrimination was expected to be resolved by means of a Feature X Modulated Target A-US association and the simultaneous discrimination by a feature X-US association. After sequential FP training, extinction of Feature X did not affect discriminative X --> A/A responding (Experiment 1), and X transferred its modulatory ability only to new targets, B, that had also been modulated (Experiment 2). This suggests that the sequential FP discrimination indeed resulted in occasion setting. Unlike expected, Feature X Extinction did not affect discriminative XA/A responding after simultaneous FP training (Experiment 3), while at the same time Feature X did show the predicted nonselective transfer to new targets, B (Experiment 4). J. M. Pearce's (1987) configural learning theory can account for most but not all findings of Experiments 3 and 4.

Inhibition of VRAC by c-Src tyrosine kinase targeted to caveolae is mediated by the Src homology domains

We used the whole cell patch-clamp technique in calf pulmonary endothelial (CPAE) cells to investigate the effect of wild-type and mutant c-Src tyrosine kinase on I(Cl,swell), the swelling-induced Cl- current through volume-regulated anion channels (VRAC). Transient transfection of wild-type c-Src in CPAE cells did not significantly affect I(Cl,swell). However, transfection of c-Src with a Ser3Cys mutation that introduces a dual acylation signal and targets c-Src to lipid rafts and caveolae strongly repressed hypotonicity-induced I(Cl,swell) in CPAE cells. Kinase activity was dispensable for the inhibition of I(Cl,swell), since kinase-deficient c-Src Ser3Cys either with an inactivating point mutation in the kinase domain or with the entire kinase domain deleted still suppressed VRAC activity. Again, the Ser3Cys mutation was required to obtain maximal inhibition by the kinase-deleted c-Src. In contrast, the inhibitory effect was completely lost when the Src homology domains 2 and 3 were deleted in c-Src. We therefore conclude that c-Src-mediated inhibition of VRAC requires compartmentalization of c-Src to caveolae and that the Src homology domains 2 and/or 3 are necessary and sufficient for inhibition.

Inhibition of volume-regulated anion channels by dominant-negative caveolin-1

Caveolae are flask-shaped invaginations of the plasma membrane formed by the association of caveolin proteins with lipid rafts. In endothelial cells, caveolae function as signal transduction centers controlling NO synthesis and mechanotransduction. We now provide evidence that the endothelial volume-regulated anion channel (VRAC) is also under the control of the caveolar system. When calf pulmonary artery endothelial (CPAE) cells were transfected with caveolin-1 Delta1-81 (deletion of amino acids 1 to 81), activation of VRAC by hypotonic cell swelling was strongly impaired. Concomitantly, caveolin-1 Delta1-81 disturbed the formation of caveolin-1 containing lipid rafts as evidenced by sucrose density gradient centrifugation. In nontransfected cells, endogenous caveolin-1 typically associated with low-density, detergent-resistant lipid rafts. However, transient expression of caveolin-1 Delta1-81 caused a redistribution of endogenous caveolin-1 to high-density, detergent-soluble membrane fractions. We therefore conclude that the interaction between caveolin-1 and detergent-resistant lipid rafts is an important prerequisite for endothelial VRAC activity.

Pre-extinction of sensory preconditioned electrodermal activity

In the present study, sensory preconditioning of human electrodermal activity was demonstrated. In the first phase of the experiment, two pairs of neutral pictures of human faces were presented (A/B and C/D) sequentially. In the second phase, one picture of one pair was immediately followed by an electrocutaneous stimulus (B+), and one picture of the other pair was not (D-). In the third phase the other picture of each pair (A and C) was tested. The effect of A and C alone presentations (pre-extinction) between the first and the second phase was investigated. When only those participants that showed reliable B+/D- differentiation were considered, the extinction group did not show stronger conditioned electrodermal activity to A than to C, whereas the control group did. These findings suggest that sensory preconditioning of anticipatory/preparatory responding only occurs when the pre-conditioned stimulus (A) actually predicts the conditioned stimulus (B).

The emotional stroop task and chronic pain: what is threatening for chronic pain sufferers?

Using a computer version of the emotional stroop task, it was investigated whether chronic pain patients display an involuntary attentional shift towards pain-related information (sensory, affective pain words and injury related words). Multiple regression analyses were used to investigate which pain and psychosocial variables (pain severity, pain-related fear, pain catastrophizing and negative affect) were predictive of attentional bias. Results indicated: (1) that there was an attentional bias towards the sensory pain words; and (2) that current pain intensity was predictive of the effect. No other attentional effects were found. The results are discussed in terms of possible reasons for the difficulty of demonstrating attentional bias in chronic pain patients.

Differential effects of injections of anti-mu and anti-delta monoclonal antibodies on B-cell populations in adult mice: regulation of xenoreactive natural antibody-producing cells

BACKGROUND

The depletion of differential B cell and xenoreactive natural antibodies (XNA) by anti-delta and anti-mu injections was analyzed in adult mice. Sequential treatment with anti-delta and then anti-mu induces a complete depletion of B cells and XNA and represents a potential approach to induce xenograft tolerance.

METHODS

Adult mice were injected with anti-mu, anti-delta, anti-delta then anti-mu, or control isotype monoclonal antibodies from day 0 to day 14. The different B-cell populations were analyzed by FACS and immunohistology. Ig production was tested by ELISA. XNA were analyzed by FACS.

RESULTS

Anti-mu injections induced a depletion of IgMhigh, immature B cells, marginal zone B cells, and B1 cells and an increase of IgG-XNA production. Anti-delta injections induced mature conventional IgDhigh B-cell depletion and increased IgM-XNA production. Interestingly, sequential injections of anti-delta then anti-mu induced a depletion of immature B cells, mature B cells (MZ, B2, and B1), and XNA.

CONCLUSIONS

These results demonstrate that mature B-cell depletion in adult mice can be obtained by mAb injections and depends on the surface immunoglobulin cross-linking threshold. Indeed, anti-mu mAb depleted IgMhigh B cells (MZ and B1) and anti-delta, IgDhigh B cells (B2). The differential B-cell suppression shows that conventional B cells are responsible in the IgG-XNA production and MZ and B1 cells in the IgM-XNA production. Sequential repeated injections of anti-delta then anti-mu mAb depleted all B-cell populations and suppressed the whole XNA production.

Saccharomyces boulardii upgrades cellular adaptation after proximal enterectomy in rats

BACKGROUND

Saccharomyces boulardii is a non-pathogenic yeast which exerts trophic effects on human and rat small intestinal mucosa.

AIMS

To examine the effects of S boulardii on ileal adaptation after proximal enterectomy in rats.

METHODS

Wistar rats, aged eight weeks, underwent 60% proximal resection or transection and received by orogastric intubation either 1 mg/g body wt per day lyophilised S boulardii or the vehicle for seven days. The effects on ileal mucosal adaptation were assessed eight days after surgery.

RESULTS

Compared with transection, resection resulted in mucosal hyperplasia with significant decreases in the specific and total activities of sucrase, lactase, and maltase. Treatment of resected animals with S boulardii had no effect on mucosal hyperplasia but did upgrade disaccharidase activities to the levels of the transected group. Enzyme stimulation by S boulardii was associated with significant increases in diamine oxidase activity and mucosal polyamine concentrations. Likewise, sodium dependent D-glucose uptake by brush border membrane vesicles, measured as a function of time and glucose concentration in the incubation medium, was significantly (p<0.05) increased by 81% and three times respectively in the resected group treated with S boulardii. In agreement with this, expression of the sodium/glucose cotransporter-1 in brush border membranes of resected rats treated with S boulardii was enhanced twofold compared with resected controls.

CONCLUSION

Oral administration of S boulardii soon after proximal enterectomy improves functional adaptation of the remnant ileum.

Neither extended sequential nor simultaneous feature positive training result in modulation of evaluative flavor-flavor conditioning in humans

In previous attempts to induce Pavlovian modulation of human evaluative flavor-flavor associations, the recurrent finding was that exposure to a Feature Positive (FP) schedule (XA+/A-), in which flavor A was reinforced by the aversive flavor Tween20 if and only if it was accompanied by a feature stimulus X, did not result in the expected X-modulated dislike for target A, but in simple unconditional A-US associations. The first experiment reported here investigated if more extended training results in a shift from simple A-US learning to the development of X-modulated A-US associations. Participants were exposed to a 32-trial, 4-session sequential FP schedule using flavors both for feature and target stimuli. The modulatory and/or excitatory power of the stimuli was assessed after each training session. After initial training, participants again acquired a simple unmodulated target A-US association. Contrary to expectations, the additional training sessions did not result in participants gradually learning the XA+/A- discrimination, but rather seemed to corroborate the already established A-US association. This was true whether or not participants acquired valid explicit knowledge about the conditional X-->(A-US) relation. The second experiment tested the hypothesis that what can be described as conditional flavor preferences may actually be based on a configural learning process. Participants were exposed to a single-session, eight-trial XA+/A- simultaneous discrimination schedule, the parameters of which were selected so as to enhance the probability of configuring XA, while simultaneously making it likely to observe a pattern of evaluations similar to an X-modulated dislike for A (X was less salient than A). Even though there was good evidence that participants noticed flavor X, they again failed to solve the XA+/A- discrimination and most probably acquired an association between the more salient flavor A and the US. The possibility is discussed that evaluative learning, unlike expectancy learning, might ultimately prove not to be subject to modulation.

Negative affect, respiratory reactivity, and somatic complaints in a CO2 enriched air inhalation paradigm

Subjects scoring high on negative affectivity (NA) are known to report more psychosomatic complaints than subjects scoring low. According to the symptom perception hypothesis, high NA subjects attend more to somatic sensations and interpret these as more threatening. We investigated the relationship between NA and psychosomatic complaints in a group of high and low NA subjects (N = 72) in, (a) a questionnaire study, and (b) in a laboratory setting. The latter involved the inhalation of three different gas mixtures (room air, 5.5% and 7.5% CO2-enriched air) while respiratory responses were registered. Subjective complaints were measured after each trial. High NA subjects reported more complaints than low NA subjects in the questionnaire study. However, NA had no main effects on complaints in the laboratory study and did not interact with the effects of gas mixture on complaints. During room air trials, NA correlated only with general arousal complaints when a strong respiratory challenge had not been given before. The pattern of results suggests that experimental inductions of complaints may largely wipe out NA-related differences in attentional/interpretative processes that may mediate the NA complaints link.

Affective Simon effects using facial expressions as affective stimuli

Two experiments are reported in which facial expressions were presented and participants were asked to respond with the word POSITIVE or NEGATIVE on the basis of a relevant feature of the facial stimuli while ignoring the valence of the expression. Results showed that reaction times were influenced by the match between the valence of the facial expression and the valence of the correct response when the identity of the presented person had to be determined in order to select the correct response, but not when the gender of the presented person was relevant. The present experiments illustrate the flexibility of the affective Simon paradigm and provide a further demonstration of the generalizability of the affective Simon effect.

Affective priming using a color-naming task: a test of an affective-motivational account of affective priming effects

The affective priming effect, i.e. shorter response latencies for affectively congruent as compared to affectively incongruent prime-target pairs, is now a well-documented phenomenon. Nevertheless, little is known about the specific processes that underlie the affective priming effect. Several mechanisms have been put forward by different authors, but these theoretical accounts only apply to specific types of tasks (e.g. evaluation lexical decisions) or are rather unparsimonious. Hermans, De Houwer, and Eelen (1996) recently proposed a model of the affective priming effect that is based on the idea of the activation of corresponding or conflicting affective-motivational action tendencies. According to this model, affectively incongruent prime-target pairs should not only lead to relatively longer response latencies on tasks that concern the target word itself (target-specific tasks, e.g. evaluation pronunciation), but also on tasks that are unrelated to the actual identity of the specific target word. This hypothesis was tested in a series of four experiments in which participants had to name the color in which the target word was printed. In spite of procedural variations, results showed that the congruence between the valence of prime and target did not influence the color-naming times. The present results therefore provide no direct support for the affective-motivational account of the affective priming effect. Suggestions for future research are provided.

Implicit and explicit memory for shape, body weight, and food-related words in patients with anorexia nervosa and nondieting controls

Twelve patients with anorexia nervosa and 12 control participants watched a series of 64 words. There were 4 word types: anorexia related, positive, negative, and neutral. The last 3 types were anorexia unrelated. Anorexia-related words had the same affective valence as the neutral control words. Next, the participants completed an explicit memory test (cued recall) and an implicit memory test (word stem completion). Results showed a strong explicit memory bias for anorexia-related words for patients with anorexia nervosa but not for nondieting controls. There was no evidence for a similar bias in implicit memory. Results are discussed in the context of cognitive biases in psychopathology.

Implicit and explicit memory for shape, body weight, and food-related words in patients with anorexia nervosa and nondieting controls

Twelve patients with anorexia nervosa and 12 control participants watched a series of 64 words. There were 4 word types: anorexia related, positive, negative, and neutral. The last 3 types were anorexia unrelated. Anorexia-related words had the same affective valence as the neutral control words. Next, the participants completed an explicit memory test (cued recall) and an implicit memory test (word stem completion). Results showed a strong explicit memory bias for anorexia-related words for patients with anorexia nervosa but not for nondieting controls. There was no evidence for a similar bias in implicit memory. Results are discussed in the context of cognitive biases in psychopathology.

Expression of insulin receptors and of 60-kDa receptor substrate in rat mature and immature enterocytes

The mechanism(s) by which rat immature enterocytes exhibit increased responsiveness to insulin before weaning is unknown. Therefore, we have analyzed the distribution, ontogeny, and molecular properties of insulin receptors (IR) and of related substrates in immature and mature enterocytes. IR were studied by radioligand binding assays, cross-linking labeling, immunohistochemistry, and in vitro phosphorylated substrates by immunoprecipitation. Regardless of age, 125I-insulin binding to IR was five times higher in crypt cells than in villus cells and two times higher in the ileum than in the jejunum. Binding capacity to villus cells from sucklings (day 14) exceeded three times that of older animals (day 30 and day 60). Scatchard analysis of equilibrium binding data confirmed an age-related decrease in low- and high-affinity receptor classes without change in affinity constants. In concordance, both alpha- and beta-IR subunits were more abundant in immature than in mature membranes. In vitro, insulin elicited the phosphorylation of three membrane proteins (96, 60 and 42 kDa), whose signals were virtually inhibited by preincubating membranes with antireceptor monoclonal antibodies. By immunoprecipitation, the 60-kDa signal was rapidly detected as a tyrosine-phosphorylated protein, expressed in mature and immature membranes, and identified as a receptor substrate phosphorylated in vitro by the IR tyrosine kinase. In conclusion, 1) increased responsiveness of rat immature enterocytes to insulin could be related to high membrane concentrations of IR and 2) normal rat enterocytes express a 60-kDa phosphotyrosine protein identified as a direct substrate of the IR tyrosine kinase.

Ursodeoxycholic acid therapy in pediatric patients with progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) is a lethal inherited childhood cholestasis of hepatocellular origin. Different subtypes of PFIC have been described according to serum gamma-glutamyl transpeptidase (GGT) activity. There is currently no effective medical therapy available for children with PFIC. We report on 39 patients with PFIC who received ursodeoxycholic acid (UDCA) orally (20-30 mg/kg b.w./day) for a period of 2 to 4 years. Group 1 (n = 26) consisted of children with normal GGT activity, and group 2 (n = 13) of children with high GGT activity. Within group 1, liver tests normalized in 11 children, improved in 5, and stabilized or worsened in 10. Within group 2, liver tests normalized in six children, improved in four, and stabilized or worsened in three. Improvement of parameters was associated with an enrichment of the circulating pool of bile acids with UDCA. Hepatosplenomegaly and pruritus disappeared or diminished in children in whom liver tests normalized. In nine of these children, liver tests worsened and normalized again after stopping and restarting UDCA. Liver histology assessed in four children after normalization of liver tests and 2 years of treatment showed a decrease in fibrosis. We conclude that UDCA should be considered in the initial therapeutic management of children with PFIC, because it appears effective in resolving or improving the liver function and the clinical status of a fair proportion of children. Chronic UDCA therapy might thus avoid the need for liver transplantation in some children with PFIC.

Evaluative decision latencies mediated by induced affective states

Recent priming studies (e.g. Hermans, De Houwer & Eelen, 1994, Cognition and Emotion, 8, 515-533) have demonstrated that response latencies to target stimuli are mediated by the affective relation between prime and target. The time needed to evaluate or pronounce targets is facilitated if preceded by similarly valenced primes, but is inhibited for trials on which prime and target have an opposite affective valence. These data suggest that information stored in memory is associatively linked with similarly evaluated information, through association with some general representation of goodness or badness. To investigate whether affective priming is merely one type of conventional semantic priming, or whether it is mediated by affective responses, the affective context provided by the primes was replaced in this study by the induction of an emotional state using a Musical Mood Induction procedure (Depression/Elation). Subjects had to evaluate target pictures as quickly as possible. The data revealed a significant Mood Change (More Depressed/Less Depressed/No Change) x Target Valence (Positive/Negative) interaction, indicating that emotional states can mediate evaluate response latencies to affectively valenced target stimuli. The results are interpreted in the context of a biphasic emotion theory, and are related to previous research on mood congruency effects on perceptual responses.

Orthotopic liver transplantation for Crigler-Najjar type I disease in six children

Hyperbilirubinemia in Crigler-Najjar disease type I (CN) can be partially controlled by daily phototherapy, but these children remain at permanent risk of developing brain damage due to kernicterus. Because liver transplantation is the only available curative treatment for liver-based inborn errors of metabolism, orthotopic liver transplantation (OLT) was performed in six patients with CN. Mean age at surgery was 52.5 months (range 27 to 100). Despite a mean daily phototherapy of 12.4 +/- 0.8 hr, mean bilirubin of the 6 patients was 388 microM/L (range 175 to 703) before OLT; one of them was also being treated with tin-protoporphyrin. All 6 had elevated AST/ALT, ranging from 1.4 to 6 times upper normal values. Complications occurred in three patients after OLT, including miliary tuberculosis in one, graft rejection and retransplantation in one, and hepatic artery thrombosis in one. All patients survive with normal serum bilirubin level (follow up 6 to 116 months). Four have normal enzymes on post-OLT follow-up (30 to 95 months), follow a normal education program, and have a normal social life. One recently transplanted patient has progressively normalizing liver function tests 6 months after OLT. One patient transplanted at 8 y.o. (now 116 months post-OLT) has moderate neurological delay due to pretransplant kernicterus, and posttransplant chronic persistent hepatitis. Our series shows that OLT cures hyperbilirubinemia in CN patients, with an excellent survival prospect. The procedure should be decided upon before neurological sequelae occur, since these persist after transplantation.

Mitochondrial respiratory chain defect: a new etiology for neonatal cholestasis and early liver insufficiency

Two siblings presented with neonatal cholestasis and early liver insufficiency. The older was admitted for end-stage cirrhosis with severe hypoglycemia and had long-term successful liver transplant at the age of 15 months. The second child presented a similar neonatal history of cholestasis, hypoglycemia, hyperlactacidemia, liver insufficiency and progressive cirrhosis. Extensive work-up excluded all known causes of neonatal cholestasis. Gluconeogenesis was found normal following alanine and fructose infusion. Repeated hypoglycemia with early post-prandial hyperlactacidemia led us to investigate the mitochondrial respiratory chain enzyme activities. Selective defects of complexes I, III and IV, coded by mitochondrial DNA, were detected in liver tissue of this patient and on preserved frozen tissue from his sibling, whilst normal activities were found in liver tissue samples from control patients with end-stage liver diseases. No extrahepatic manifestations were found. We conclude that liver deficiency of mitochondrial respiratory chain enzymes may cause liver disease in neonates, associated with hypoglycemia and post-prandial hyperlactacidemia. The disease is cured by liver transplantation.

Estimating the cost of compensating victims of medical negligence

The current system in Britain for compensating victims of medical injury depends on an assessment of negligence. Despite the sporadic pressure on the government to adopt a "no fault" approach, such as exists in Sweden, the negligence system will probably remain for the immediate future. The cost of this system was estimated to be 52.3m pounds for England 1990-1. The problem for the future, however, is one of forecasting accuracy at provider level: too high a guess and current patient care will suffer; too low a guess and future patient care will suffer. The introduction of a mutual insurance scheme may not resolve these difficulties, as someone will have to set the rates. Moreover, the figures indicate that if a no fault scheme was introduced the cost might be four times that of the current system, depending on the type of scheme adopted.

The role of CS-US contingency in human evaluative conditioning

Recent studies suggest that in Pavlovian conditioning, two different processes may be operative: signal learning and evaluative learning, resulting in two qualitatively different associative structures. Signal-learning is hypothesized to be responsible for providing us with genuine predictors (CS) for significant events (US). This proposition logically entails that the statistical-correlational relation, i.e. the contingency between CS and US should be a crucial determinant of signal learning. Evaluative conditioning, on the other hand, refers to the observation that the mere pairing of neutral with (dis)liked stimuli changes the valence of the originally neutral stimuli in a (negative) positive direction. As argued elsewhere, evaluative conditioning is probably based on the CS acquiring a mere referential value to the US, without any genuine CS-US expectancy being involved. From this, it was hypothesized that evaluative conditioning might not be dependent on CS-US contingency. Using the standard evaluative conditioning paradigm, four different levels of CS-US contingency were created on a between-subject base. The overall effect of evaluative conditioning was strongly significant, and was not mediated by awareness of the CS-US relation. Of crucial importance, this conditioning effect did not interact with the level of contingency, supporting the hypothesis that CS-US contingency is not a crucial determinant of evaluative conditioning. Moreover, this effect was obtained in a situation in which Ss simultaneously evidence to have consciously registered quite accurately the different levels of CS-US contingency.

Bile acids and conjugates identified in metabolic disorders by fast atom bombardment and tandem mass spectrometry

From a study of the collision-activated fragmentation of bile acids, a qualitative analytical method based on negative ion fast atom bombardment tandem mass spectrometry has been developed. The times for sample preparation and analyses are short. Both free and conjugated bile acids are detected as they occur in biological fluids, without derivatization. For identifying bile acids and conjugates, the method offers better specificity and sensitivity than does the fast atom bombardment mass spectrometric technique alone. Specific scan modes have been developed for the selective detection of taurine conjugates, delta 4-unsaturated taurine conjugates, delta 4-3-keto free acids and their glycine conjugates, free acids and glycine conjugates bearing a hydroxyl group at the C-12 position, sulfates of glycine and taurine conjugates, and a C29 dicarboxylic bile acid, specific for generalized peroxisomal disorders. Applications of this technique demonstrate its potential usefulness, principally in the diagnosis of several peroxisomal disorders.