Guest Editorial: Critical Thinking in Education and Research-Why and How?

"A responsible scientist is able to step back, critically reflect on his or her own doings, and also explain them to a wider audience. Critical thinking includes the ability to talk to people working in other areas, as well as the broader public. It has to be taught to students and fostered at the university level, and should be practiced in relation to one's own work …" Read more in the Guest Editorial.

Salivary Alpha-Amylase Correlates with Subjective Heat Pain Perception.

OBJECTIVE: Self-reports of pain are important for an adequate therapy. This is a problem with patients and infants who are restricted in providing an accurate verbal estimation of their pain. Reliable, real-time, economical, and non-invasive physiological correlates might contribute to a more comprehensive description of pain. Salivary alpha-amylase constitutes one candidate biomarker, which reflects predominantly sympathetic nervous system alterations under stressful conditions and can be measured non-invasively. The current study investigated the effects of acute heat pain on salivary alpha-amylase activity. METHODS: Heat pain tolerance was measured on the non-dominant forearm. Participants completed visual analog scales on pain intensity and unpleasantness. Saliva samples were collected directly after pain induction. SUBJECTS: Twenty-seven healthy volunteers were recruited for this study. RESULTS: While salivary alpha-amylase levels correlated positively with intensity and unpleasantness ratings in response to acute heat pain stimuli, there was no corresponding association with pain tolerance. CONCLUSIONS: Salivary alpha-amylase is suggested to be an indirect physiologic correlate of subjective heat pain perception. Future studies should address the role of salivary alpha-amylase depending on the origin of pain, the concerned tissue, and other pain assessment methods.

Temporal Processing in Bistable Perception of the Necker Cube.

Perception of ambiguous figures is unstable and alternates repeatedly between possible interpretations. Some approaches to explaining this phenomenon have, so far, assumed low-level bottom-up mechanisms like adaptation and mutual inhibition of underlying neural assemblies. In contrast, less precise top-down approaches assume high-level attentional control mechanisms generalised across sensory modalities. In the current work we focused on specific aspects of the top-down approach. In a first study we used dwell times (periods of transiently stable percepts) and the parameters of dwell time distribution functions to compare the dynamics of perceptual alternations between visual (Necker cube) and auditory ambiguity (verbal transformation effect). In a second study we compared the endogenous alternation dynamics of the Necker cube with parameters from two attention tasks with different regimes of temporal dynamics. The first attention task (d2) is characterised by endogenous self-paced dynamics, similar to the dynamics underlying perceptual alternations of ambiguous figures, and we found clear correlations between dwell time parameters (Necker cube) and processing speed (d2 task). The temporal dynamics of the second (go/no-go) attention task, in contrast, are exogenously governed by the stimulus protocol, and we found no statistically significant correlation with the Necker cube data. Our results indicate that both perceptual instability and higher-level attentional tasks are linked to endogenous brain dynamics on a global coordinating level beyond sensory modalities.

Quality of Animal Experiments in Anti-Angiogenic Cancer Drug Development--A Systematic Review.

Translation from preclinical animal research to clinical bedside has proven to be difficult to impossible in many fields of research (e.g. acute stroke, ALS and HIV vaccination development) with oncology showing particularly low translation rates (5% vs. 20% for cardiovascular diseases). Several investigations on published preclinical animal research have revealed that apart from plain species differences, translational problems can arise from low study quality (e.g. study design) or non-representative experimental conditions (e.g. treatment schedule). This review assessed the published experimental circumstances and quality of anti-angiogenic cancer drug development in 232 in vivo studies. The quality of study design was often insufficient; at least the information published about the experiments was not satisfactory in most cases. There was no quality improvement over time, with the exception of conflict of interest statements. This increase presumably arose mainly because journal guidelines request such statements more often recently. Visual inspection of data and a cluster analysis confirmed a trend described in literature that low study quality tends to overestimate study outcome. It was also found that experimental outcome was more favorable when a potential drug was investigated as the main focus of a study, compared to drugs that were used as comparison interventions. We assume that this effect arises from the frequent neglect of blinding investigators towards treatment arms and refer to it as hypothesis bias. In conclusion, the reporting and presumably also the experimental performance of animal studies in drug development for oncology suffer from similar shortcomings as other fields of research (such as stroke or ALS). We consider it necessary to enforce experimental quality and reporting that corresponds to the level of clinical studies. It seems that only clear journal guidelines or guidelines from licensing authorities, where failure to fulfill prevents publication or experimental license, can help to improve this situation.

How much reproducibility do we need in human and veterinary pathology?

In diagnostic and research reports as well as text-books of human and veterinary pathology repeatability, reproducibility, inter- and intra-observer variation are mentioned rarely as a problem in preparing diagnosis from macroscopic and/or microscopic samples and discussed inconsistently. However, optimal care and restoration of health for a patient are dependent on reliability of diagnosis, therapy, prognosis and prophylaxis. This requires for all tests and procedures a maximal repeatability and reproducibility, a sensitivity and specificity of 85-95% for procedures and methodologies and a comparison of results procedures and methodologies to a gold standard. Looking at the various steps on the road to diagnosis in pathology this is influenced by a series of laboratory steps preparing tissue samples but most importantly reproducibility depends on the handling of visual information in the central nervous system of the individual diagnostician. Thus reproducibility in this context has to be divided into at least three levels: individual (epistemological, organoleptic, inter- and intra-observer variation, and formal/technological- and normative reproducibility). The aim of the present manuscript is to stimulate the reflection among the pathology experts on this most important topic.

Thermodynamics of the interaction between oxytocin and its myometrial receptor in sheep: a stepwise binding mechanism.

Entropy (ΔS), enthalpy (ΔH) and heat capacity (ΔCp) changes attending the oxytocin interaction with its two binding sites on myometrial cell membranes in sheep were derived from the temperature dependence of Kd values. The high affinity oxytocin site (Kd on the order of 10(-9)mol l(-1), 25 °C), ascribed to the oxytocin receptor (OXTR), is entropy-driven in the temperature range 0-37 °C. Enthalpy component prevails as a driving force in the binding to the low affinity site (Kd ≈ 10(-7)) within the higher temperature range. ΔCp values in both cases do not differ significantly from zero but become highly relevant in the presence of a GTP analog (10(-4)M GTP-γS). Under these conditions, ΔCp in the low site interaction becomes negative and ΔS is shifted toward negative values (enthalpy drift); ΔCp of the high affinity site rises to a high positive value and the interaction is even more strongly entropy driven. Atosiban, a competitive antagonist of oxytocin at OXTR displays a single significant binding site on myometrial cells (Kd about 10(-7)mol l(-1)). Thermodynamic profiles of atosiban and the low affinity oxytocin site show conspicuous similarities, indicating that the inhibitor is bound to the low affinity site, and not, with a lower affinity, to the putative receptor protein. It is suggested that the interaction of oxytocin with its responding system on myometrial membranes follows in two distinct steps that are likely to be associated with several independent binding domains in the GPCR receptor.

Help-seeking in people with exceptional experiences: results from a general population sample.

BACKGROUND: Exceptional experiences (EE) are experiences that deviate from ordinary experiences, for example precognition, supernatural appearances, or déjà vues. In spite of the high frequency of EE in the general population, little is known about their effect on mental health and about the way people cope with EE. This study aimed to assess the quality and quantity of EE in persons from the Swiss general population, to identify the predictors of their help-seeking, and to determine how many of them approach the mental health system. METHODS: An on-line survey was used to evaluate a quota sample of 1580 persons representing the Swiss general population with respect to gender, age, and level of education. Multinomial logistic regression was applied to integrate help-seeking, self-reported mental disorder, and other variables in a statistical model designed to identify predictors of help-seeking in persons with EE. RESULTS: Almost all participants (91%) experienced at least one EE. Generally, help-seeking was more frequent when the EE were of negative valence. Help-seeking because of EE was less frequent in persons without a self-reported mental disorder (8.6%) than in persons with a disorder (35.1%) (OR = 5.7). Even when frequency and attributes of EE were controlled for, people without a disorder sought four times less often help because of EE than expected. Persons with a self-reported diagnosis of mental disorder preferred seeing a mental health professional. Multinomial regression revealed a preference for healers in women with less education, who described themselves as believing and also having had more impressive EE. CONCLUSION: Persons with EE who do not indicate a mental disorder less often sought help because of EE than persons who indicated a mental disorder. We attribute this imbalance to a high inhibition threshold to seek professional help. Moreover, especially less educated women did not approach the mental health care system as often as other persons with EE, but preferred seeing a healer.

Combinatorial chemistry by ant colony optimization.

BACKGROUND: Prioritizing building blocks for combinatorial medicinal chemistry represents an optimization task. We present the application of an artificial ant colony algorithm to combinatorial molecular design (Molecular Ant Algorithm [MAntA]). RESULTS: In a retrospective evaluation, the ant algorithm performed favorably compared with other stochastic optimization methods. Application of MAntA to peptide design resulted in new octapeptides exhibiting substantial binding to mouse MHC-I (H-2K(b)). In a second study, MAntA generated a new functional factor Xa inhibitor by Ugi-type three-component reaction. CONCLUSION: This proof-of-concept study validates artificial ant systems as innovative computational tools for efficient building block prioritization in combinatorial chemistry. Focused activity-enriched compound collections are obtained without the need for exhaustive product enumeration.

Exhaustive proteome mining for functional MHC-I ligands.

We present the development and application of a new machine-learning approach to exhaustively and reliably identify major histocompatibility complex class I (MHC-I) ligands among all 20(8) octapeptides and in genome-derived proteomes of Mus musculus , influenza A H3N8, and vesicular stomatitis virus (VSV). Focusing on murine H-2K(b), we identified potent octapeptides exhibiting direct MHC-I binding and stabilization on the surface of TAP-deficient RMA-S cells. Computationally identified VSV-derived peptides induced CD8(+) T-cell proliferation after VSV-infection of mice. The study demonstrates that high-level machine-learning models provide a unique access to rationally designed peptides and a promising approach toward "reverse vaccinology".

Scrutinizing MHC-I binding peptides and their limits of variation.

Designed peptides that bind to major histocompatibility protein I (MHC-I) allomorphs bear the promise of representing epitopes that stimulate a desired immune response. A rigorous bioinformatical exploration of sequence patterns hidden in peptides that bind to the mouse MHC-I allomorph H-2K(b) is presented. We exemplify and validate these motif findings by systematically dissecting the epitope SIINFEKL and analyzing the resulting fragments for their binding potential to H-2K(b) in a thermal denaturation assay. The results demonstrate that only fragments exclusively retaining the carboxy- or amino-terminus of the reference peptide exhibit significant binding potential, with the N-terminal pentapeptide SIINF as shortest ligand. This study demonstrates that sophisticated machine-learning algorithms excel at extracting fine-grained patterns from peptide sequence data and predicting MHC-I binding peptides, thereby considerably extending existing linear prediction models and providing a fresh view on the computer-based molecular design of future synthetic vaccines. The server for prediction is available at http://modlab-cadd.ethz.ch (SLiDER tool, MHC-I version 2012).

Naloxone modulates visual judgments of similarity but not dissimilarity.

Endogenous opioids have been implicated in mediating (placebo) analgesia, in reward processes, and in the regulation of socially relevant emotions. To explore their potential contributions to higher cognitive functions, we used a novel task with tachistoscopically presented (for 150 ms) pairs of meaningless figures. Healthy right-handed men judged the similarities and dissimilarities between the two figures on a visual analogue scale (VAS) in two separate runs. In a double-blind, between-subjects design, subjects were administered intravenously either 0.2-mg/kg naloxone or placebo 10 min prior to the task, and VAS judgments and response latencies were measured. We found a significant interaction between substance group and type of judgment: The magnitude of the similarity judgments was lower in the naloxone than in the placebo group, while dissimilarity judgments remained uninfluenced by the treatment. Reaction latencies and mood scores, assessed before and after substance administration, did not differ between the two groups, indicating that the findings did not rely on altered motor performance or motivation. We suggest that naloxone decreased the "similarity criterion" in comparative judgments, indicating its potentially modulatory effect on visual cognition. The task introduced here could be used for the implicit study and quantification of subtle affective-cognitive processes beyond the level of mere questionnaire data.

A new tool for real-time pain assessment in experimental and clinical environments.

Pain measurement largely depends on the ability to rate personal subjective pain. Nevertheless, pain scales can be difficult to use during medical procedures. We hypothesized that pain can be expressed intuitively and in real-time by squeezing a pressure sensitive device. We developed such a device called "Painmouse(®)" and tested it on healthy volunteers and patients in two separate studies: Sixteen male participants rated different painful heat stimuli via Painmouse(®) and a Visual Analog Scale (VAS). Retest was done one week later. Participants clearly distinguished four distinct pain levels using both methods. Values from the first and second sessions were comparable. Thereafter, we tested the Painmouse(®) by asking twelve female and male leg- ulcer patients to continuously squeeze it during the whole length of their wound-dressing change. Patients rated each step of dressing change on an 11-point numeric rating scale. Painmouse(®) ratings were highest for the wound cleaning and debridement step. Application of the new dressing was not evaluated as very painful. On the other hand, numeric scale ratings did not differentiate between dressing change steps. We conclude that the Painmouse(®) enables pain assessment even under difficult clinical circumstances, such as during a medical treatment in elderly patients.

Monitoring stage fright outside the laboratory: an example in a professional musician using wearable sensors.

We implemented and tested a wearable sensor system to measure patterns of stress responses in a professional musician under public performance conditions. Using this sensor system, we monitored the cellist's heart activity, the motion of multiple body parts, and their gradual changes during three repeated performances of a skill-demanding piece in front of a professional audience. From the cellist and her teachers, we collected stage fright self-reports and performance ratings that were related to our sensor data analysis results. Concomitant to changes in body motion and heart rate, the cellist perceived a reduction in stage fright. Performance quality was objectively improved, as technical playing errors decreased throughout repeated renditions. In particular, from performance 1 to 3, the wearable sensors measured a significant increase in the cellist's bowing motion dynamics of approximately 6% and a decrease in heart rate. Bowing motion showed a marginal correlation to the observed heart rate patterns during playing. The wearable system did not interfere with the cellist's performance, thereby allowing investigation of stress responses during natural public performances.

Pleasure-related analgesia activates opioid-insensitive circuits.

Recent findings suggest that pain and pleasure share common neurochemical circuits, and studies in animals and humans show that opioid-mediated descending pathways can inhibit or facilitate pain. We explored the role of endogenous opioid neurotransmission in pleasure-related analgesia. µ-Opioidergic activity was blocked with 0.2 mg/kg naloxone to assess its effects on hedonic responses to pleasant emotional pictures (International Affective Picture System) and its modulating effects on heat pain tolerance. Naloxone did not alter subjective and autonomous reactions to pleasure induction or overall mood of participants. In addition, pleasure-related increases in pain tolerance persisted after reversal of endogenous µ-opioidergic neurotransmission. Subjective pain intensity and unpleasantness ratings increased after naloxone administration. These findings suggest that, in addition to opioid-sensitive circuits, mainly opioid-insensitive pain-modulating circuits are activated during pleasure-related analgesia.

Placebo-mediated, Naloxone-sensitive suggestibility of short-term memory performance.

Physiological studies of placebo-mediated suggestion have been recently performed beyond their traditional clinical context of pain and analgesia. Various neurotransmitter systems and immunological modulators have been used in successful placebo suggestions, including Dopamine, Cholecystokinin and, most extensively, opioids. We adhered to an established conceptual framework of placebo research and used the µ-opioid-antagonist Naloxone to test the applicability of this framework within a cognitive domain (e.g. memory) in healthy volunteers. Healthy men (n=62, age 29, SD=9) were required to perform a task-battery, including standardized and custom-designed memory tasks, to test short-term recall and delayed recognition. Tasks were performed twice, before and after intravenous injection of either NaCl (0.9%) or Naloxone (both 0.15 mg/kg), in a double-blind setting. While one group was given neutral information (S-), the other was told that it might receive a drug with suspected memory-boosting properties (S+). Objective and subjective indexes of memory performance and salivary cortisol (as a stress marker) were recorded during both runs and differences between groups were assessed. Short-term memory recall, but not delayed recognition, was objectively increased after placebo-mediated suggestion in the NaCl-group. Naloxone specifically blocked the suggestion effect without interfering with memory performance. These results were not affected when changes in salivary cortisol levels were considered. No reaction time changes, recorded to uncover unspecific attentional impairment, were seen. Placebo-mediated suggestion produced a training-independent, objective and Naloxone-sensitive increase in memory performance. These results indicate an opioid-mediated placebo effect within a circumscribed cognitive domain in healthy volunteers.

Prefrontal cortex modulates placebo analgesia.

Expectations and beliefs modulate the experience of pain, which is particularly evident in placebo analgesia. The dorsolateral prefrontal cortex (DLPFC) has been associated with pain regulation and with the generation, maintenance and manipulation of cognitive representations, consistent with its role in expectation. In a heat-pain paradigm, we employed non-invasive low-frequency repetitive transcranial magnetic stimulation (rTMS) to transiently disrupt left and right DLPFC function or used the TMS device itself as a placebo, before applying an expectation-induced placebo analgesia. The results demonstrated that placebo significantly increased pain threshold and pain tolerance. While rTMS did not affect pain experience, it completely blocked placebo analgesia. These findings suggest that expectation-induced placebo analgesia is mediated by symmetric prefrontal cortex function.

Heat pain threshold and tolerance show no left-right perceptual differences at complementary sites of the human forearm.

Pain threshold and pain tolerance of heat noxious stimuli were assessed to determine whether they are equivalent when measured at three equidistant sites of both volar forearms. Heat pain threshold and tolerance were measured in 18 healthy volunteers using a standard stimulation device consisting of a thermode. Pain threshold and pain tolerance did not differ within and across forearm sites. Experimenters addressing heat pain threshold and tolerance in healthy volunteers may freely choose and change stimulation sites on both volar forearms, without the risk of confounding site effects on dependent variables. This data completes previous reports on side effects by analyzing the effect of site on the forearm for both heat pain threshold and tolerance. The absence of side and site effects may contribute to setting a more secure basis for assessments of laterality effects of painful stimulation.

Changes in self-perceived role identity modulate pain perception.

Pain is an experience including physiological and psychological factors. We assume that emotions may be elicited and increased through self-perceived role identity and that change of role identity alters quality and intensity of pain perception. We used role-play strategies to assess whether pain can be better tolerated whenever, in an unavoidable and unpleasant context, role identity confers pain a meaningful and thus suitable character. We induced antithetic roles in 21 actors who received heat stimuli on their arms before and after role-play conditions. Pain tolerance, skin conductance and voice signals were measured. Pain tolerance increased for heroes/heroines and decreased for faint-hearts. Men showed higher pain tolerance. Heroes/heroines evaluated heat stimuli as more intense. Faint-hearts found pain stimuli more affectively loaded at lower temperatures. Women showed higher pain ratings. Hence, self-perception influences pain perception. Role-play strategies may be of value for new pain management strategies.

Characterization of two splice variants of human organic anion transporting polypeptide 3A1 isolated from human brain.

In the present study we isolated two splice variants of organic anion transporting polypeptide 3A1 (OATP3A1_v1 and OATP3A1_v2) from human brain. OATP3A1_v2 lacks 18 amino acids (aa) at the COOH-terminal end (692 aa) but is otherwise similar in sequence to OATP3A1_v1 (710 aa). OATP3A1_v1 exhibits a wide tissue distribution, with expression in testis, various brain regions, heart, lung, spleen, peripheral blood leukocytes, and thyroid gland, whereas OATP3A1_v2 is predominantly expressed in testis and brain. On the cellular and subcellular levels OATP3A1_v1 could be immunolocalized in testicular germ cells, the basolateral plasma membrane of choroid plexus epithelial cells, and neuroglial cells of the gray matter of human frontal cortex. Immunolocalization of OATP3A1_v2 included Sertoli cells in testis, apical and/or subapical membranes in choroid plexus epithelial cells, and neurons (cell bodies and axons) of the gray and white matter of human frontal cortex. The rodent ortholog Oatp3a1 was also widely distributed in rat brain, and its localization included somatoneurons as well as astroglial cells. Transport studies in cRNA-injected Xenopus laevis oocytes and in stably transfected Chinese hamster ovary FlpIn cells revealed a similar broad substrate specificity for both splice variants. Transported substrates include prostaglandin (PG)E(1) and PGE(2), thyroxine, and the cyclic oligopeptides BQ-123 (endothelin receptor antagonist) and vasopressin. These studies provide further evidence for the involvement of OATPs in oligopeptide transport. They specifically suggest that OATP3A1 variants might be involved in the regulation of extracellular vasopressin concentration in human brain and thus might influence the neuromodulation of neurotransmission by cerebral neuropeptides such as vasopressin.