Looking into myself: Changes in interoceptive sensitivity during mirror self‐observation

Interoceptive sensitivity is an essential component of recent models of “the self.” Increased focus on the self (e.g., self‐observation in a mirror) can enhance aspects of self‐processing. We examined whether self‐observation also enhances interoceptive sensitivity. Participants performed a heartbeat detection task while looking at their own face in a mirror or at a black screen. There was significant improvement in interoceptive sensitivity in the mirror condition for those participants with lower interoceptive sensitivity at baseline. This effect was independent of the order of conditions, gender, age, body mass index, habitual exercise, and changes in heart rate. Our results suggest that self‐observation may represent a viable way of manipulating individuals' interoceptive sensitivity, in order to directly test causal relations between interoceptive sensitivity and exteroceptive self‐processing.     

Interoceptive sensitivity and physical effort: implications for the self-control of physical load in everyday life

This study examined the relationship between interoceptive sensitivity and the behavioral self-regulation of physical load. According to their performance in a heartbeat detection task, 34 participants were classified as good or poor heartbeat perceivers. Participants pedaled on a bicycle ergometer for 15 min and were free to choose the tempo of their cycling. Good heartbeat perceivers covered a significantly shorter distance and showed a significantly smaller increase in mean heart rate, stroke volume, and cardiac output. There were significant negative correlations between heartbeat perception score and covered distance, changes in heart rate, changes in stroke volume, and changes in cardiac output. These results were not explained by differences in physical fitness level (PWC150). The findings suggest that good heartbeat perceivers show a more finely tuned behavioral self-regulation of physical load than poor heartbeat perceivers.     

Cardiac sensitivity in children: Sex differences and its relationship to parameters of emotional processing

In adults, the level of ability to perceive one's own body signals plays an important role for many concepts of emotional experience as demonstrated for emotion processing or emotion regulation. Representative data on perception of body signals and its emotional correlates in children is lacking. Therefore, the present study investigated the cardiac sensitivity of 1,350 children between 6 and 11 years of age in a heartbeat perception task. Our main findings demonstrated the distribution of cardiac sensitivity in children as well as associations with interpersonal emotional intelligence and adaptability. Furthermore, independent of body mass index, boys showed a significantly higher cardiac sensitivity than girls. We conclude that cardiac sensitivity in children appears to show weaker but similar characteristics and relations to emotional parameters as found in adults, so that a dynamic developmental process can be assumed.     

Sensitivity to mechanical stimuli and the role of general sensory and perceptual processes in heartbeat detection

Sensitivity to heartbeat sensations is commonly assessed using tasks that require individuals to judge the simultaneity of heartbeats and tones. In two experiments, we investigated the suitability of this paradigm for examining cardioception. In the first experiment, participants judged the simultaneity of near–threshold vibrations and suprathreshold tones. Precision in judging vibration–tone simultaneity was directly related to the detectability of the mechanical stimuli, thereby supporting use of the simultaneity paradigm to assess heartbeat detection. In the second experiment, we examined the influences of sensitivity to mechanical stimuli and the ability to make intermodality simultaneity judgments on the precision of heartbeat detection. We measured participants' vibrotactile thresholds, precision in judging light–tone simultaneity, and precision in judging heartbeat–tone simultaneity. The ability to judge the simultaneity of lights and tones accounted for 24.3% of the variance in precision of heartbeat detection, and mechanical sensitivity accounted for a further 8.5%.     

Adaptive spatio-temporal filtering of disturbed ECGs: a multi-channel approach to heartbeat detection in smart clothing

Intermittent disturbances are common in ECG signals recorded with smart clothing: this is mainly because of displacement of the electrodes over the skin. We evaluated a novel adaptive method for spatio-temporal filtering for heartbeat detection in noisy multi-channel ECGs including short signal interruptions in single channels. Using multi-channel database recordings (12-channel ECGs from 10 healthy subjects), the results showed that multi-channel spatio-temporal filtering outperformed regular independent component analysis. We also recorded seven channels of ECG using a T-shirt with textile electrodes. Ten healthy subjects performed different sequences during a 10-min recording: resting, standing, flexing breast muscles, walking and pushups. Using adaptive multi-channel filtering, the sensitivity and precision was above 97% in nine subjects. Adaptive multi-channel spatio-temporal filtering can be used to detect heartbeats in ECGs with high noise levels. One application is heartbeat detection in noisy ECG recordings obtained by integrated textile electrodes in smart clothing.     

A method of constant stimuli for examining heartbeat detection: Comparison with the Brener-Kluvitse and Whitehead methods

A method of constant stimuli (MCS) for measuring heartbeat detection was examined by comparing performance on this method with the Brener and Kluvitse (BK) method and a variant of the Whitehead (WH′) method. All methods required subjects to judge the simultaneity of heartbeat sensations and tones, and each yielded measures of judgment precision and of the temporal location of heartbeat sensations relative to the electrocardiogram R-wave. Both measures were found to be significantly correlated across tasks. A greater proportion of subjects met criteria for classification as heartbeat detectors on the MCS (54%) and BK (50%) tasks than on the WH’task (33%). In the MCS and BK tasks, subjects judged tones presented 100–300 ms after the R-wave to be most simultaneous with heartbeat sensations. Intratask correlations showed that only the MCS procedure yielded stable measurements of both judgment precision and temporal location. The MCS procedure possesses commendable psychometric properties and provides a simpler means than the BK procedure of examining heartbeat detection.     

Short‐term food deprivation increases amplitudes of heartbeat‐evoked potentials

Nutritional state (i.e., fasting or nonfasting) may affect the processing of interoceptive signals, but mechanisms underlying this effect remain unclear. We investigated 16 healthy women on two separate days: when satiated (standardized food intake) and after an 18‐h food deprivation period. On both days, heartbeat‐evoked potentials (HEPs) and cardiac and autonomic nervous system activation indices (heart rate, normalized low frequency heart rate variability [nLF HRV]) were assessed. The HEP is an EEG pattern that is considered an index of cortical representation of afferent cardiovascular signals. Average HEP activity (R wave +455–595 ms) was enhanced during food deprivation compared to normal food intake. Cardiac activation did not differ between nutritional conditions. Our results indicate that short‐term food deprivation amplifies an electrophysiological correlate of the cortical representation of visceral‐afferent signals originating from the cardiovascular system. This effect could not be attributed to increased cardiac activation, as estimated by heart rate and nLF HRV, after food deprivation.     

Basophil allergen threshold sensitivity,CD‐sens,is a measure of allergen sensitivity in asthma

Background Allergic asthma is IgE‐mediated and the IgE‐sensitisation is usually demonstrated by skin prick tests (SPT) and IgE antibody determinations in serum. The SPT and IgE‐antibody values do not directly predict if the allergy clinically contributes to the asthma. There is therefore a need for new objective tests that may indicate the clinical importance of an IgE‐sensitisation. Objective To evaluate basophil allergen threshold sensitivity (CD‐sens) as a measure of allergen sensitivity in allergic asthma. Methods Twenty‐six subjects with stable, intermittent allergic asthma were tested with SPT and spirometry, and methacholine and allergen inhalation challenges to determine methacholine PD₂₀ (provocative dose causing a 20% drop in forced expiratory volume in 1 s) and allergen PD₂₀. The results were compared with CD‐sens and serological parameters, i.e. IgE‐ and IgG4 antibodies to the relevant allergens. Results A significant correlation was found between CD‐sens and allergen PD₂₀ (P=0.01; r=0.49; n=26) as well as between CD‐sens and the ratio of allergen PD₂₀ to methacholine PD₂₀ (P=0.007; r=0.52; n=26). In patients with a moderate to low degree of bronchial hyperresponsiveness there was an excellent correlation (P=0.0001; r=0.88, n=13) between CD‐sens and allergen sensitivity. No relation to either allergen PD₂₀ or the ratio was found for basophil allergen reactivity measured as CD63 up‐regulation at high concentrations of the respective allergen. Conclusions and Clinical Relevance CD‐sens was found to be an objective marker of airway allergen sensitivity in stable allergic asthmatics, that may be used to predict airway responsiveness when bronchial challenge tests cannot be performed. Cite this as: B. Dahlén, A. Nopp, S. G. O. Johansson, M. Eduards, M. Skedinger and J. Adédoyin, Clinical & Experimental Allergy, 2011 (41) 1091–1097.     

Parkin regulates paclitaxel sensitivity in breast cancer via a microtubule‐dependent mechanism

Parkin is an E3 ubiquitin ligase encoded by the Parkin gene (also called PARK2, located at 6q25.2‐q27) and is involved in the pathogenesis of Parkinson's disease and the development of cancer. Recently, Parkin has been demonstrated to interact with the microtubule cytoskeleton. However, the biological implication of the Parkin–microtubule axis has been poorly explored. In this study, we report for the first time that Parkin modulates sensitivity of the chemotherapeutic agent paclitaxel in breast cancer, via a microtubule‐dependent mechanism. Our data reveal that Parkin binds to the outer surface of microtubules and increases paclitaxel–microtubule interaction, resulting in enhanced paclitaxel‐induced microtubule assembly and stabilization. Our data further show that Parkin promotes the activity of paclitaxel to trigger multinucleation and apoptosis, rendering breast cancer cells more sensitive to this drug. Moreover, Parkin expression correlates with the pathological response of tumours to preoperative paclitaxel‐containing chemotherapy. In addition, expression of Parkin also correlates with the sensitivity of paclitaxel in primary cultures of breast cancer cells. Our results identify Parkin as a novel mediator of paclitaxel sensitivity in breast cancer. In addition, our study suggests that patients harbouring tumours with high Parkin level would be more likely to benefit from paclitaxel‐containing regimens. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Factorized sensitivity estimation for artifact suppression in phase‐cycled bSSFP MRI

Objective: Balanced steady‐state free precession (bSSFP) imaging suffers from banding artifacts in the presence of magnetic field inhomogeneity. The purpose of this study is to identify an efficient strategy to reconstruct banding‐free bSSFP images from multi‐coil multi‐acquisition datasets. Method: Previous techniques either assume that a naïve coil‐combination is performed a priori resulting in suboptimal artifact suppression, or that artifact suppression is performed for each coil separately at the expense of significant computational burden. Here we propose a tailored method that factorizes the estimation of coil and bSSFP sensitivity profiles for improved accuracy and/or speed. Results: In vivo experiments show that the proposed method outperforms naïve coil‐combination and coil‐by‐coil processing in terms of both reconstruction quality and time. Conclusion: The proposed method enables computationally efficient artifact suppression for phase‐cycled bSSFP imaging with modern coil arrays. Rapid imaging applications can efficiently benefit from the improved robustness of bSSFP imaging against field inhomogeneity.     

Evaluation of a new screening assay for HTLV‐1 and ‐2 antibodies for large‐scale use

Laboratory testing for Human T‐lymphotropic Virus type 1 and 2 (HTLV‐1 and ‐2) infections has become routine in blood transfusion, tissue transplantation and clinical diagnoses in many countries worldwide. Screening is usually based on the detection of antibodies to HTLV‐1 and/ or ‐2. The number of commercially available assays is limited, and among them, ELISA tests based on microtiter format are most commonly used. Recently, the new rHTLV‐I/II assay (Abbott Laboratories, Abbott Park, IL) was released; this assay was developed for an automatic large‐scale screening platform. This assay was evaluated using pre‐characterized serum panels and routine samples from the clinical laboratory. The sensitivity was 100% for HTLV‐1 and ‐2 (99/99 and 42/42, respectively, including one sample that was dually reactive, HTLV‐1 + 2). To test assay specificity, panels of blood donor sera, specimens from patients with autoimmune diseases and some viral infections were used. False‐reactive samples from previous HTLV diagnoses were also included. With these panels, the specificity was 99.4% (619/623). However, the four false‐reactive samples all belonged to the group of samples that were previously considered as false‐reactive for HTLV‐antibodies. All other samples were negative by the rHTLV‐I/II assay, and thus 100% specificity was obtained. The 1,412 samples tested in the clinic by this assay in routine use were all negative (100% specificity). Taken together, the overall specificity was 99.8%. The assay was sensitive, specific and appropriate for the large‐scale screening of samples for HTLV‐1/2 antibodies. J. Med. Virol. 82:1606–1611, 2010. © 2010 Wiley‐Liss, Inc.     

Comparison of baroreceptor cardiac reflex sensitivity estimates from inter‐systolic and ECG R‐R intervals

Baroreceptor reflex sensitivity (BRS) is frequently evaluated using the spontaneous sequence method. Many of these studies use the inter‐systolic interval (ISI) derived from a blood pressure monitor (e.g., Finapres) as interbeat interval measure instead of the traditionally recommended R‐R series derived from the ECG. In this study, we examine possible differences between estimates of BRS from ISI and ECG R‐R intervals. BRS was evaluated in 35 participants under three conditions: rest, mental arithmetic, and recovery periods. Although correlations between the two estimates are very high (all rs>.9), small but significant differences were found: the measures from ISI systematically yield higher BRS values and result in the detection of a greater number of reflex sequences. The higher BRS values from measures of ISI are due to the effects of pulse transit time fluctuations associated with the sequences of change in blood pressure.     

Relationships between muscle morphology and insulin sensitivity are improved after adjustment for intra‐individual variability in 70‐year‐old men

The purpose of this investigation was to examine to what extent variability in the muscle morphology and insulin sensitivity influence the correlation between them. Reproducibility of muscle characteristics was estimated in duplicate biopsies from the same thigh of 23 subjects from a cohort of 70‐year‐old men. The coefficient of variation (CV) for different characteristics of muscle morphology was between 11 and 42% in duplicate biopsies. Coefficient of variation for markers of insulin sensitivity ranged between 12 and 39%. The variability reflected by intra‐class correlation ranged from 0.23 to 0.60 for muscle morphology and from 0.68 to 0.96 for estimates of insulin sensitivity. The correlation analysis between muscle morphology and insulin resistance was performed in a sample of 515 men from the cohort, correlation coefficients were calculated with (r_true) and without (r) adjustment for intra‐individual variation. Insulin sensitivity showed a positive relationship with percentage of type I fibres (r_true=0.33, r=0.21; P < 0.0001) and capillary density (r_true=0.43, r=0.21; P < 0.0001) and negative correlations with percentage of type IIB fibres (r_true=–0.35, r=–0.24; P < 0.0001). Capillary density was inversely correlated to insulin. Thus, an obvious improvement of the correlation was seen after correcting intra‐individual variation. In conclusion, owing to the low degree of reproducibility of muscle morphology variables and insulin sensitivity, implying a noticeable underestimation of correlations, the r‐values should be adjusted for within‐subject variation in order to demonstrate a more accurate estimate of the strength of the relationships studied.     

Single‐molecule detection of cancer mutations using a novel PCR‐LDR‐qPCR assay

Detection of low‐abundance mutations in cell‐free DNA is being used to identify early cancer and early cancer recurrence. Here, we report a new PCR‐LDR‐qPCR assay capable of detecting point mutations at a single‐molecule resolution in the presence of an excess of wild‐type DNA. Major features of the assay include selective amplification and detection of mutant DNA employing multiple nested primer‐binding regions as well as wild‐type sequence blocking oligonucleotides, prevention of carryover contamination, spatial sample dilution, and detection of multiple mutations in the same position. Our method was tested to interrogate the following common cancer somatic mutations: BRAF:c.1799T>A (p.Val600Glu), TP53:c.743G>A (p.Arg248Gln), KRAS:c.35G>C (p.Gly12Ala), KRAS:c.35G>T (p.Gly12Val), KRAS:c.35G>A (p.Gly12Asp), KRAS:c.34G>T (p.Gly12Cys), and KRAS:c.34G>A (p.Gly12Ser). The single‐well version of the assay detected 2–5 copies of these mutations, when diluted with 10,000 genome equivalents (GE) of wild‐type human genomic DNA (hgDNA) from buffy coat. A 12‐well (pixel) version of the assay was capable of single‐molecule detection of the aforementioned mutations at TP53, BRAF, and KRAS (specifically p.Gly12Val and p.Gly12Cys), mixed with 1,000–2,250 GE of wild‐type hgDNA from plasma or buffy coat. The assay described herein is highly sensitive, specific, and robust, and potentially useful in liquid biopsies.     

Scale development of a measure to assess community‐based and clinical intervention group environments

Though group interventions are widely used in community‐based and clinical settings, there are few brief instruments for assessing the group environment. Two studies on the development of a brief measure to assess intervention group environments are described, and psychometric properties of the new scale are presented. The new measure is based on Moos' (1994) Group Environment Scale (GES). Participants in the studies were from two independent randomized controlled clinical trials (RCTs) of group interventions (combined N=334). In Study 1 (N=139), the factor content of the original 90‐item GES was examined. The scale was shortened, the response format was changed, and items were adapted and added to in an effort to increase applicability to community‐based and clinical intervention groups. In Study 2 (N=195), the new scale was evaluated, the factor solution obtained in Study 1 was cross‐validated, and subsequently the length of the scale was shortened again. The final scale contains 25 items with three subscales. Reliability and validity of the new scale was examined. Finally, the research and practice implications of the scale are discussed. © 2008 Wiley Periodicals, Inc.     

Hypochondriasis Y‐BOCS: a study of the psychometric properties of a clinician‐administered semi‐structured interview to assess hypochondriacal thoughts and behaviours

Introduction: This study investigated the psychometric properties of the first clinician‐administered semi‐structured interview for assessing the severity of hypochondriacal symptoms. The Hypochondriasis Yale‐Brown Obsessive–Compulsive Scale (H‐YBOCS) consisted of three a priori dimensions: hypochondriacal obsessions, compulsions and avoidance. Methods: The 16‐item interview was conducted with 112 participants with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, hypochondriasis. We analysed factor analytic structure, reliability, construct validity and sensitivity to change. Results: Factor analysis supported a three‐factor model similar to the a priori dimensions. Internal consistency ranged from satisfactory to good. Inter‐rater reliability was excellent. The construct validity was low to moderate. The H‐YBOCS was sensitive for measuring changes in symptom severity. Conclusion: The H‐YBOCS is a (factorially) valid and coherent interview with a high level of agreement across different raters. The relatively low discriminant validity could be due to co‐morbid anxiety and depressive disorders. Overall, the H‐YBOCS seems to be a promising contribution to the assessment of hypochondriasis. Copyright © 2009 John Wiley & Sons, Ltd. Key Practitioner Message: ? The hypochondriasis Y‐BOCS is a feasible clinician rated interview to assess the severity of hypochondriacal complaints.