Differences between Staphylococcus aureus lineages isolated from ovine and caprine mastitis but not between isolates from clinical or subclinical mastitis

Staphylococcus aureus is an important mastitis pathogen, causing both clinical mastitis (CM) and subclinical mastitis (SCM) in small ruminants. In general, CM has a low incidence in sheep and goats but can be very severe and costly. In contrast, subclinical mastitis (SCM) is common but is associated with less cost. For both sheep and goats, S. aureus is the main cause of CM and is associated with SCM cases with a high SCC. Recently, specific lineages of S. aureus have been identified that are associated with CM rather than SCM in dairy cows. It is unknown whether specific S. aureus lineages are associated with CM in goats and sheep. The aim of this study was to compare the clonal complex (CC), staphylococcal protein A (spa) type, leukocidin lukM-lukF' presence, and potential to produce LukMF' in vitro between CM and SCM S. aureus mastitis isolates obtained from sheep and goats. Differences between isolates from different host species were also compared. Ovine (CM, n = 12; SCM, n = 29) and caprine (CM, n = 14; SCM, n = 30) isolates were obtained from 8 sheep flocks and 8 goat herds in the Netherlands. Overall, the isolates belonged to CC133 (85%), CC398 (7%), CC425 (5%), and CC45 (2%). Seventeen spa types were found, including 6 novel types; the predominant types were t2678 (34%), t544 (18%), and t3583 (18%). Although CC133 was dominant among both sheep and goat isolates, spa type CC133/t2678 was associated with ovine isolates, whereas CC133/t544 and CC133/t3583 were found mostly in goats. The presence of lukM-lukF' among the S. aureus isolates was high (87%), especially in CC133 (96%) and CC425 (100%), but the genes were absent in CC45 and CC398. In vitro-cultured lukM-lukF'-positive isolates produced LukM (71 out of 74 positive isolates tested) in the range of 0.4 to 5.0 µg/mL. Interestingly, the goat-associated lineages CC133/t544 and CC133/t3583 produced more LukM in vitro than the sheep-associated CC133/t2678. We found no difference in LukMF' production potential between CM and SCM isolates. In sheep as well as in goats, no association was found between genotype and CM or SCM, demonstrating that the same lineages of S. aureus are responsible for both CM and SCM. These results suggest that subclinically infected animals in a herd or flock likely act as the reservoir of S. aureus causing CM. This highlights the importance of early identification and control of SCM and suggests that controlling SCM within a herd is an effective intervention to prevent CM in small ruminants.

End-joining long nucleic acid polymers

Many experiments involving nucleic acids require the hybridization and ligation of multiple DNA or RNA molecules to form a compound molecule. When one of the constituents is single stranded, however, the efficiency of ligation can be very low and requires significant individually tailored optimization. Also, when the molecules involved are very long (>10 kb), the reaction efficiency typically reduces dramatically. Here, we present a simple procedure to efficiently and specifically end-join two different nucleic acids using the well-known biotin–streptavidin linkage. We introduce a two-step approach, in which we initially bind only one molecule to streptavidin (STV). The second molecule is added only after complete removal of the unbound STV. This primarily forms heterodimers and nearly completely suppresses formation of unwanted homodimers. We demonstrate that the joining efficiency is 50 ± 25% and is insensitive to molecule length (up to at least 20 kb). Furthermore, our method eliminates the requirement for specific complementary overhangs and can therefore be applied to both DNA and RNA. Demonstrated examples of the method include the efficient end-joining of DNA to single-stranded and double-stranded RNA, and the joining of two double-stranded RNA molecules. End-joining of long nucleic acids using this procedure may find applications in bionanotechnology and in single-molecule experiments.

Red blood cell and plasma phospholipid arachidonic and docosahexaenoic acid levels at birth and cognitive development at 4 years of age

OBJECTIVE

The long-chain polyunsaturated fatty acids (LCPUFAs) docosahexaenoic acid (DHA) and arachidonic acid (AA) have biophysical properties that may mediate behavioral outcome, especially cognitive development. This study examined the relationship between the LCPUFA-status at birth and cognitive development at 4 years of age.

METHODS

Cognitive development of 128 full-term neonates, whose umbilical venous plasma and/or red blood cell phospholipid DHA and AA levels were known, was assessed at 4 years of age. Pearson correlation coefficients were calculated between cognitive development and DHA, AA, maternal intelligence, birth weight, duration of breast-feeding and paternal educational attainment. Multiple linear regressions were employed with cognitive development as the dependent variable and whereby the above-mentioned covariables were entered in step one while each of the four LCPUFAs was entered in step two.

RESULTS

In bivariate analysis, maternal intelligence, birth weight, maternal smoking habits during pregnancy, paternal education and duration of breast-feeding showed significant correlations with cognitive development (p<0.01). The association of cognitive development with DHA and AA measured zero in bivariate analysis (plasma levels: r=0.03 and r=-0.03, respectively; erythrocyte levels: r=0.01 and r=0.05) and in multiple regression analysis (plasma DHA r=0.01, p=0.88; plasma AA r=0.02, p=0.80; erythrocyte DHA r=-0.01, p=0.95) except for erythrocyte AA (r=0.15, p=0.09).

CONCLUSION

No evidence was found for an association of the DHA or AA-status at birth with cognitive development at 4 years of age.

The urge to smoke depends on the expectation of smoking

AIMS

An earlier study (Dols et al. 2000) suggested that cue-induced urge to smoke depends on the expectation of smoking. The present study tried to replicate the findings under stringently controlled conditions.

DESIGN

A 2 (context) x 2 (cues) x 6 (trial) within-subject design. Each smoker entered two different contexts; one context predicted the future occurrence of smoking (i.e. one puff of a cigarette) and one context predicted the non-occurrence of smoking. In each context smokers were exposed to smoking cues (i.e. cigarettes and lighter) or not.

SETTING

Laboratory at Maastricht University.

PARTICIPANTS

Thirty-two daily smokers, smoking at least five cigarettes a day for at least 2 years.

MEASUREMENTS

Participants reported their urge to smoke in each context in the presence and absence of smoking cues using a computerized visual analogue scale (VAS).

FINDINGS

The results revealed that the urge to smoke was higher in a context in which smoking was expected relative to a context in which it was not expected. As in the previous study the urge-inducing effect of smoking cues was larger in the smoking context than in the non-smoking context. Moreover, smoking cues did not have a significant effect in the non-smoking context.

CONCLUSIONS

It was shown that smoking cues elicit craving due mainly to a generated expectation of the occurrence of smoking and less due to salience or long history of associative learning. Theoretical and practical implications of the results are discussed.

On becoming neutral: effects of experimental neutralizing reconsidered

Behaviour Research and Therapy 34 (1996) 889-898 found that writing out a negative thought produced anxiety and an urge to neutralize the thought, that instructing participants to neutralize the thought reduced anxiety/neutralization urge in the short run (i.e. within 2 min), but that in the control group 20 min without instruction was attended by the same reduction in anxiety/urge to neutralize ("natural decay"). The observations were made with pariticipants who scored high on "thought action fusion" and the experiment was set up as exerimental model of obsessions. We repeated the study with participants that were not selected on thought action fusion. All the findings reported by Behaviour Research and Therapy 34 (1996) 889-898 were replicated. Correlational analysis indicated that the strength of the effect was not related to scores on scales measuring "thought action fusion". Behaviour Research and Therapy 34 (1996) 889-898 did not assess whether non-neutralizing was followed by immediate reductions in distress. We did assess this and found that the larger part of the immediate reduction of distress after neutralization also occurs when no neutralization instruction is given. The effects of neutralization instructions in the present type of experiment are considerably less powerful than suggested earlier.

Two-dimensional imaging of electronic wavefunctions in carbon nanotubes

The drive towards the development of molecular electronics is placing increasing demands on the level of control that must be exerted on the electronic structure of materials. Proposed device architectures ultimately rely on tuning the interactions between individual electronic states, which amounts to controlling the detailed spatial structure of the electronic wavefunctions in the constituent molecules. Few experimental tools are available to probe this spatial structure directly, and the shapes of molecular wavefunctions are usually only known from theoretical investigations. Here we present scanning tunnelling spectroscopy measurements of the two-dimensional structure of individual wavefunctions in metallic single-walled carbon nanotubes; these measurements reveal spatial patterns that can be directly understood from the electronic structure of a single graphite sheet, and which represent an elegant illustration of Bloch's theorem at the level of individual wavefunctions. We also observe energy-dependent interference patterns in the wavefunctions and exploit these to directly measure the linear electronic dispersion relation of the metallic single-walled carbon nanotube.

Autobiographical memories become less vivid and emotional after eye movements

OBJECTIVES

To test (1) whether eye movements during retrieval of emotional memories are followed by less vividness and less emotionality of future recollections, (2) whether this effect, if present, is stronger than the effects of a control activity (finger tapping), (3) whether the alleged effects of tapping and eye movements are stronger than a no-movement, control condition (mere imagery), (4) whether reductions in vividness and emotionality after eye movements (and finger tapping) are specific to negative memories or also occur in the case of positive memories.

METHOD

Sixty healthy volunteers recalled either positive or negative memories and scored the vividness and emotionality of the recollections. Next, memories were recalled whilst the participant was performing rapid eye movements, finger tapping, or not performing a dual task. Then participants were asked to recall the event again and to rate its vividness and emotionality.

RESULTS

Compared to finger tapping and the no-dual-task condition, recollections after eye movements made future recollections less vivid. After eye movements, but not after the other interventions, negative memories became less negative, and positive memories became less positive.

CONCLUSION

The findings show that eye movements not only reduce vividness and emotionality of memories during the eye moving, but also affect future recollections, during which no eye movements are made. Some theoretical explanations are discussed. As to clinical implications, it is suggested that if there is a role for eye-movement-based treatments, it is very limited.

Attention, arousal and expectancies in anxiety and sexual disorders

This paper reviews experimental studies of sexual disorders and anxiety disorders. Studies were mainly carried out in the laboratories and clinics with which each of the two authors is associated. Sex and anxiety are rather antipodal emotions but contrary to traditional views, there is no reason to believe that anxiety disorders are driven by underlying sexual problems or that sexual problems are maintained by anxiety. Both sex research and anxiety research focused on selective processing of disorder relevant information in patients. More in particular, studies are clustered in three groups. First, the authors examined selective attention for threat-related material in anxious patients and for non-sex-related material in sexually dysfunctional patients. Second, the (mis)interpretation of response information in both disorders is compared. Finally the authors discuss biased expectancies in anxiety and sexual disorders. Symmetries and asymmetries are highlighted and lines for further research are sketched.

Conscious and preconscious selective attention to social threat: different neuroendocrine response patterns

This study was designed to investigate the relationship between selective attention to social threat and neuroendocrine activity. Selective attention to social threat was measured using a supraliminal (unmasked) and a subliminal (masked) version of a pictorial emotional Stroop task, comparing color-naming latencies of neutral and angry faces. Neuroendocrine activity was assessed as (pre-task to post-task) increases in salivary cortisol and testosterone. Forty subjects were randomly assigned to the unmasked or masked version of the task. Analyses for the unmasked task revealed that post-task cortisol levels were significantly increased in subjects showing selective attention to angry faces. Results for the masked task indicated that post-task cortisol and testosterone levels were significantly increased in subjects showing preconscious selective attention to angry faces. The difference in neuroendocrine activity between tasks is suggested to depend on cortical (i.e. prefrontal) control in the unmasked task. Thus, psychological affective regulatory processes were involved in the unmasked task, whereas the neuroendocrine response patterns in the masked task indicates a biologically prepared mechanism.

Smokers can learn to influence their urge to smoke

Forty heavy smokers participated in a within-subject experiment in which the association between smoking-related cues and nicotine intake was made conditional on two neutral stimuli. Two colored cards indicated whether smoking-related cues, placed on the cards, would or would not be followed by nicotine intake. In the presence of each card, subjects were asked to rank their urge to smoke before and during the exposure to the smoking cues. The results of the present study revealed that the predictive value of a cue, in regard to the occurrence of nicotine intake, strongly determines its ability to generate craving. It was concluded that participants learned a modified predictive value of smoking cues, through a process of conditioning, and in this way influenced their urge to smoke. Furthermore, the findings suggest the reconditioning of CS-US associations as an aid in the treatment of smoking addiction.

Correlations among salivary testosterone, mood, and selective attention to threat in humans

An experiment was designed to investigate the relation among salivary testosterone, mood, and selective attention to threat. The participant group consisted of 32 nonclinical subjects (16 men and 16 women). Individuals completed the Profile Of Mood States (POMS) and performed a pictorial emotional Stroop task measuring selective attention to angry faces. Anticipating a time lag between testosterone (as measured in saliva) and cognitive emotional behavior, multiple time-coursed saliva samples were taken preceding the assessment of questionnaire and task for every subject. In both sexes, salivary testosterone was significantly related to mood (i.e., anger and tension) and selective attention to angry faces when saliva samples were taken 6 h before questionnaire and task assessment. Research on the relation between testosterone and human behavior might benefit by taking into account time lags between the behavioral manifestations and the continuously changing levels of testosterone.

Avoidant personality disorder and implicit schema-congruent information processing bias: a pilot study with a pragmatic inference task

Cognitive theory of personality disorders hypothesizes that each personality disorder is characterized by typical maladaptive schemes and that these schemas direct the processing of information resulting in schema-congruent biases. With regard to the avoidant personality disorder, these hypotheses were put to an initial test in a pilot study, using a self-report questionnaire to asses DSM-III-R personality pathology, a belief questionnaire to assess avoidant schemas and a pragmatic inference task to assess schema-congruent implicit attributional bias. Participants were students (n = 57) who scored high or low on DSM-III-R avoidant personality pathology. As predicted from cognitive theory, DSM-III-R avoidant personality pathology was associated with avoidant beliefs (t(45.1) = 4.68, p < 0.001) and avoidant beliefs were associated with schema-congruent information processing bias (t(55) = 2.17, p = 0.02, one-tailed test). However, DSM-III-R avoidant personality pathology was not associated with schema-congruent information processing bias (t(55) = 0.17, p = 0.43, one-tailed test). In addition to avoidant beliefs, low self-esteem was also related to the information processing bias. Social phobia and general personality pathology, two other control variables, were not. The findings warrant further study using the pragmatic inference task in a clinical group.

Baseline salivary cortisol levels and preconscious selective attention for threat. A pilot study

This study was conducted to examine the relationship between baseline salivary cortisol (CORT) levels and selective attention for displays of angry faces. Selective attention was investigated using a pictorial emotional Stroop task, comparing colournaming-speed of angry and neutral faces. The task was assessed in supraliminal (unmasked) and subliminal (masked) conditions to 28 non-clinical subjects (14 male and 14 female). Repeated measures analysis of variance revealed a significant interaction between median split CORT levels (low vs. high) and masked face valence (angry vs. neutral). The latter effect was mainly due to significant facilitation in the high CORT subject-group; these subjects seemed to allocate their attention away from the masked angry face. A relation between baseline CORT levels and fast withdrawal behavior is suggested.

Conditional reasoning and phobic fear: evidence for a fear-confirming reasoning pattern

In two experiments we explored the role of subjects' reasoning performance in the persistence of phobic fear. More specifically, we investigated whether (phobic) subjects are prone to selectively search for danger-confirming information when asked to judge the validity of conditional rules in the context of general and phobic threats. In both experiments, participants were presented with Wason Selection Tasks (WST) pertaining to general and phobic threats. The WSTs contained safety rules (if P then no danger) and danger rules (if P then danger). In Experiment 1 participants were high (n = 20) and low (n = 20) spider fearful students, whereas in Experiment 2 participants were untreated (n = 38) and treated (n = 27) spider phobic women and a group of non-fearful controls (n = 27). Both experiments showed that in the context of general threat, subjects predominantly rely on confirming information regarding danger rules and on falsifying information regarding safety rules. This reasoning strategy was not particularly pronounced in high fear or phobic subjects. However, only clinically diagnosed spider phobics displayed a similar reasoning strategy in the context of phobia-relevant threats. Thus, the present data seem to suggest that the mere perception of threat is already sufficient to activate a danger-confirming reasoning strategy and in case of phobic threats such a reasoning pattern logically serves to maintain or even enhance phobic fears.

Preconscious processing bias in specific phobia

The occurrence of processing bias manifested by the modified Stroop task does not require that the subjects to be aware of the stimuli presented. Earlier studies have shown that even when stimuli are backwardly masked so conscious identification is prevented, patients suffering from Generalised Anxiety Disorders slow down colour-naming masks that are preceded by threatening words. In non-patient samples, processing bias on the modified Stroop task is related to the level of trait anxiety. We tested whether this preconscious processing bias is related to anxiety per se and whether it also occurs in specific phobias. Indeed, in a group of 37 spider phobics, the intensity of phobic complaints was significantly associated with interference measures on both the masked and the unmasked modified Stroop task. Preconscious processing bias was not associated with treatment gain. Interference on the masked and unmasked Stroop task was reduced after treatment. Though the lack of a no treatment control group preludes definite conclusions, our findings suggest that preconscious biases are influenced by behaviour therapy. Results are critically discussed.

Symptom reporting and interoceptive attention in panic patients

The present study investigated whether bodily sensations reported by panic-disorder patients can be due to interoceptive attention. The attention of two groups, one of 16 panic patients and one of 17 normal control subjects was manipulated towards and away from bodily sensations. After each manipulation they had to report the sensations experienced. As expected, panic patients did report more sensations than controls in a baseline condition but against the hypothesis that a ceiling effect would occur in the panic group, both panic patients and controls reported more sensations after being instructed to attend to them. However, when their attention was diverted, panic patients showed a decrease in sensations greater than control subjects showed. The findings suggest that interoceptive attention may partly account for the sensations reported by panic patients.

Psychological treatments of panic disorder without agoraphobia: cognitive therapy versus applied relaxation

This study compared two psychological treatments of panic disorder and tested whether cognitive therapy (CT) was superior to applied relaxation (AR); and whether treatment was superior to waiting. Thirty-six outpatients of the community mental health center with the DSM-III-R diagnosis of panic disorder with no or mild agoraphobia were randomly assigned to CT or AR. Eighteen similar patients who were referred after the treatment conditions were complete constituted a waiting-list group. Treatment consisted of 12 weekly sessions. Patients self-monitored panic attacks during the whole treatment period, and the following 4 weeks, and during 1 week at a half-year follow-up. Questionnaires were filled out before and after treatment, and at 4-week and half-year follow-ups. After the first follow-up additional treatment was provided if clinically indicated. One patient dropped out of AR and was replaced. Treatment was superior to waiting in reducing panic and questionnaire scores. CT was clearly superior to AR in reducing panic frequency, and somewhat less strongly superior to AR in reducing the questionnaire scores. Depending on the assessment point, 77.8-83.3% of the CT patients was panic-free after treatment, compared to 50% of the AR and 27.7% of the waiting-list patients. In conclusion, cognitive therapy for panic is especially effective in reducing the incidence of panic attacks.

"If I feel anxious, there must be danger": ex-consequentia reasoning in inferring danger in anxiety disorders

It has been suggested that neurotic patients engage in 'emotional reasoning', i.e. draw invalid conclusions about a situation on the basis of their subjective emotional response. The present experiment investigated whether anxiety patients infer danger on the basis of their anxious response, whereas normals infer danger only on the basis of objective information. Four groups of anxiety patients (52 spider phobics, 41 panic patients, 38 social phobics, and 31 other anxiety patients) and 24 normal controls made ratings of the danger they perceived in scripts in which information about objective safety vs objective danger, and anxiety response vs non-anxiety response information were systematically varied. As hypothesized, anxiety patients were not only influenced by objective danger information, but also by anxiety response information, whereas normal controls were not. The effect was neither situation-specific, nor specific for panic patients. This tendency to infer danger on the basis of subjective anxiety ('ex-consequentia reasoning') may play a role in the development and maintenance of anxiety disorders.

An untenable rationale for treating insomnia

In 1995 Cholitz tested a breathing technique to treat insomniacs. The results were incomparably much better than typically reported. It is argued that Cholitz' explanation of his findings is untenable and that independent replications are needed.

Responding to subliminal threat cues is related to trait anxiety and emotional vulnerability: a successful replication of Macleod and Hagan (1992)

Macleod and Hagan (1992) [Behaviour Research and Therapy, 30, 151-161] reported that threat-relevant interference on a masked Stroop task, where neutral and negative words cannot be consciously perceived, is positively correlated with trait anxiety and emotional vulnerability to stressful life events. Their findings were obtained from subjects who were currently stressed. The aim of the present study was to determine whether the Macleod and Hagan findings could be replicated in a sample that was not currently stressed. Using a sample of 32 volunteers, we found a significant correlation between trait anxiety and threat-relevant interference on a masked Stroop. Furthermore, it was found that the single best predictor of vulnerability to life stress was the interference on the masked Stroop. The findings of the present study correspond quite closely to those reported by Macleod and Hagan (1992).

Overprediction of anxiety, and disconfirmatory processes, in anxiety disorders

The overprediction of anxiety phenomenon and its relationships with fear, dysfunctional and functional beliefs, and emotional experiences during confrontations with feared stimuli were investigated in two studies. Study 1 investigated exposure in vivo exercises executed by anxiety patients during treatment (n = 37). Study 2 investigated behavioural experiments executed by anxiety patients (n = 11) during cognitive treatment. In both studies patients rated various variables just before and immediately after their exercises. The results indicate that anxiety patients tend to overpredict the level of anxiety they are going to experience. There is no evidence that this phenomenon is a statistical artefact, caused for instance by a pre-test response style. There is also no evidence that the observed adjustment of incorrect anxiety predictions is a statistical artefact. A global negative emotional evaluation of the experience appears to have an adverse influence on the reduction of anxiety predictions and on the reduction of fear. Fear, and its reduction after exposure in vivo or after behavioural tests, appears to be influenced by both anxiety predictions and dysfunctional beliefs. Positive emotions and functional beliefs did not appear to play an important role. The interrelationships between these factors are comprised in a path-model which describes how emotional and cognitive information yielded by disconfirmatory experiences influences changes in anxiety predictions and changes in fear. Unexpectedly, change in dysfunctional belief did not relate directly to change in fear, but only indirectly, via change in anxiety predictions. Theoretical and therapeutical implications are discussed.

Exposure reduced agoraphobia but not panic, and cognitive therapy reduced panic but not agoraphobia

Earlier studies showed that cognitive therapy has anti-panic effects and exposure has anti-agoraphobic effects while other studies suggest that agoraphobia is a secondary complication of panic disorder. It was therefore hypothesized that cognitive therapy not only reduces panic but also agoraphobia and that it potentiates the effects of exposure in vivo. Two groups of 12 severe agoraphobics were treated with 4 sessions of cognitive therapy followed by 8 sessions of cognitive therapy combined with in vivo exposure. The other 12 received 4 sessions of 'associative therapy', a presumably inert treatment that controls for therapist attention, followed by 8 sessions of in vivo exposure that was framed in common behavioral terms. The initial cognitive therapy produced a significant reduction in panic frequency, while associative therapy did not affect panic. Neither cognitive therapy alone, nor associate therapy alone significantly reduced depression, state or trait anxiety, self-rated agoraphobia or behavioral avoidance. After adding exposure however, these parameters were clearly and significantly reduced. Cognitive therapy did not potentiate exposure effects. The results are discussed.

Selective processing of emotional information in obsessive compulsive disorder

Three possible explanations for attentional bias effects in anxious subjects have been formulated: the threat-relatedness hypothesis, the emotionality hypothesis and the concern-relatedness hypothesis. In order to investigate these three hypotheses, an experiment was carried out with 33 obsessive compulsive (OC) patients and 29 normal controls. Both groups colour-named a Stroop card with 5 word sets: neutral words and 4 emotional word sets (a 2 x 2 matrix of words, related/unrelated to obsessive compulsive disorder and positively/negatively valenced). In line with previous studies, OC patients selectively attended to negative OC-related cues; this supports the threat-relatedness hypothesis. Although the set-up of the experiment was similar to the Mathews and Klug (1993, Behaviour Research and Therapy, 31, 57-62) study, no evidence was found for the concern-relatedness hypothesis, i.e. the OC patients did not show an attentional bias for positive OC-related words. Two possible reasons for these contradicting findings are discussed.

Attentional bias and spider phobia: conceptual and clinical issues

Experimental evidence indicates that anxious subjects show an attentional bias for threat-relevant information. Foa and McNally (1986) (Cognitive Therapy and Research, 10, 477-485) and Watts et al. (1986) (British Journal of Psychology, 77, 97-108) reported that behaviour therapy can eliminate this attentional bias. A replication study was carried out in order to increase the evidence for exposure being the crucial component in reducing attentional bias. Moreover, in this study some conceptual and clinical issues are explored. The theoretical and clinical implications of the results are discussed.

Suppression of emotional and neutral material

Previous studies have indicated that suppression of a thought results in an immediate increase of the frequency of this thought and/or in a rebound effect, i.e. in a heightened frequency of this thought later on. The present study (n = 53) examined the relationship between suppression and emotionality of the to-be-suppressed material. More specifically, it was investigated whether suppression of an emotional story results in stronger immediate enhancement or thought rebounds than suppression of a neutral story. There was a clear initial enhancement effect in the group suppressing a neutral story: subjects who tried to suppress experienced more target thoughts than subjects who did not try to suppress. In the neutral-story conditions, no rebound effect occurred. In the groups exposed to an emotional story, there was neither evidence of initial enhancement nor of a rebound. As most obsessions are related to emotional themes, the present findings cast doubt on the claim that the rebound phenomenon represents a valid laboratory model for clinical obsessions.

Salivation discordant with hunger

In the present study, the authors tested whether an increase in salivation is associated with an increase in subjectively experienced hunger. After conditioning, subjects showed a significant increase in salivation flow. Hunger levels, however, were significantly decreased after conditioning. No correlation was found between salivation flow and hunger levels. It is argued that salivation responses and subjectively experienced hunger are loosely coupled systems. Salivation flow reflects the learning history of a subject which may sometimes be paralleled by a biological state which is called hunger, whereas, at other times, hunger may be absent. The authors conclude that conditioning of preparatory responses such as salivation depends on the probability relationship between exposure to cues (CSs) and food intake (US), as well as the intensity of the US.

On being led into temptation: "counterregulation" of dieters after smelling a "preload"

In the present study, it was found that dieters lost control over their food intake and "counterregulated" after merely smelling a "preload," while dieters without a "preload" were able to maintain control over their food intake. Nondieters, however, even ate marginally less after smelling a "preload" than they did in a no-preload condition. Apparently, actually breaking one's diet and such subsequent thoughts as "I've blown my diet, I might as well continue to eat" is not necessary for counterregulation to occur. The observation that merely smelling a "preload" is sufficient to produce "counterregulation" in dieters but not in nondieters challenges the explanatory power of the widely held cognitive explanation of experimental counterregulation in preloaded dieters. An explantation in terms of conditioning is put forward.

[Experimental possibilities of biological provocation of panic attacks]

On the point of anxiety states, behavioural sciences have only recently been provided with sufficient operational definitions of clinical concepts to enable us to start working on the construction of valid models for the different disorders. Panic attacks are defined as attacks manifested by discrete periods of apprehension or fear, concomitant with at least four marked vegetative sensations, as described in the DSM-III. Several interventions have proved to be able to mimic experimentally such episodes in vulnerable patients, providing the researcher with valuable models for panic research such as the lactate infusion technique, the single CO2 inhalation model and, to a lesser extent, the hyperventilation provocationtest. The study of these models may be a major contribution to a better understanding of panic anxiety, both from a biological and behavioural point of view. Biological observations of those models point to pH changes and ionic shifts as a physiological concomitant in the genesis of experimentally induced panic, and suggests that hypersensitive chemoreceptive structures of the CNS may be implicated. As to the behavioural aspects of the models, there is strong evidence for the ancient phobophobia, or "fear of fear" idea, which may explain the invaldating recurrence of panic attacks.

Clinical and non-clinical binges

A study was conducted to determine if, and in what respects, clinical binges (reported by bulimic subjects) are different from non-clinical binges (reported by a non-clinical population). Furthermore, the study tested whether the DSM-III-R criteria and other variables that are retrospectively claimed to be defining characteristics indeed differentiate binges from non-binge eating episodes. Clinical binges appeared to differ from non-clinical binges as to amount of calories ingested and duration. With respect to subjective experience, clinical and non-clinical binges did not differ. The DSM-III-R criteria for binge eating discriminate clinical and non-clinical binges quite well from non-binges. With the addition of other seemingly important variables, binges are not discriminated better from non-binges than with the DSM-III-R variables alone. It is argued that the difference between pathological binge eating and non-clinical binge eating is mainly a matter of severity.

Restrained eaters are rapidly habituating sensation seekers

Several authors have pointed to similarities between eating disorders and addictive behaviors. In earlier studies, addicts were found to score high on the Sensation Seeking Scale (SSS) and to habituate rapidly to neutral stimuli. In this study, we found experimental support for an addiction model of eating disorders: restrained eaters also scored significantly higher on the Sensation Seeking Scale and also habituated significantly quicker to a series of neutral stimuli than unrestrained eaters. No clear evidence was found for the hypothesis that restrained eaters score lower on measurements of anxiety. It is hypothesized that rapid habituation promotes sensation seeking, which may be manifested in excessive consumption of either drugs or food. Restraint may be a strategy to prevent negative consequences of sensation seeking and excessive consumption. The model is related to earlier experimental findings.

Effects of low pulmonary CO2 on panic anxiety

In order to investigate the possible role of hyperventilation in the pathogenesis of panic, 11 panic patients and eight normal controls underwent a hyperventilation provocation test. The word "hyperventilation" itself was not used; the subjects were told the test was meant to measure the amount of carbon dioxide in their expired air. End tidal pCO2 was reduced to less than half of its initial value, resulting in a significant increase in physical symptoms, both in patients and controls. However, there proved to be no significant increase in subjective anxiety. It is suggested, that hypocarbia alone is not sufficient to provoke anxiety in panic disorder patients.

Some remarks on the nosology of anxiety states and panic disorders

It is argued that the panic attacks characteristic of anxiety neurosis may be elicited by interoceptive stimuli. The feared sensations are usually associated with anxiety and anxiety neurosis can be conceptualised as a phobophobia. Behavioral research and theory suggest that exposure to the feared interoceptive sensations is the treatment of choice for phobophobics. Reports of successful interventions are discussed.