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result(s) for
"Schepers, Jan"
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Symmetry and spatial distribution of muscle glucose uptake in the lower limbs during walking measured using FDG-PET
by
Kolk, Sjoerd
,
Verdonschot, Nico
,
Schepers, Jan
in
Activities of daily living
,
Adult
,
Asymmetry
2019
This study aimed to elucidate whether muscle activity (in terms of glucose uptake) between the legs can be considered symmetrical during walking. Furthermore, we aimed to determine whether the [18F]-fluorodeoxyglucose was distributed heterogeneously throughout each muscle, and if so, whether areas of high uptake would be clustered.
Ten healthy participants walked on a treadmill at self-selected comfortable walking speed for a total of 90 minutes, 60 minutes before and 30 minutes after intravenous injection of 50 MBq [18F]-fluorodeoxyglucose. Thereafter, a positron emission tomography/computed tomography scan of the lower limb was acquired. Three-dimensional muscle contours of 78 (= 39x2) muscles of the left and right lower limb were semi-automatically determined from magnetic resonance imaging scans. After non-rigid registration, those muscle contours were used to extract [18F]-fluorodeoxyglucose uptake from the positron emission tomography scans.
Large asymmetries were observed in the lower leg muscles (e.g. median absolute asymmetry index of 42% in the gastrocnemius medialis) and in the gluteus minimus (30% asymmetry) and gluteus medius (15% asymmetry), whereas the uptake in the thighs was relatively symmetrical between the limbs (<6% asymmetry). These were not related to limb-dominance nor to inter-limb differences in muscle volume. The [18F]-fluorodeoxyglucose distribution was not distributed normally; most voxels had a relatively low standardized uptake value, and a minority of voxels had a relatively high standardized uptake value. The voxels with higher [18F]-fluorodeoxyglucose uptake were distributed heterogeneously; they were clustered in virtually all muscles.
The findings in this study challenge the common assumption of symmetry in muscle activity between the limbs in healthy subjects. The clustering of voxels with high uptake suggests that even in this prolonged repetitive task, different spatial regions of muscles contribute differently to walking than others.
Journal Article
Validity and time course of surgical fear as measured with the Surgical Fear Questionnaire in patients undergoing cataract surgery
by
Gramke, Hans-Fritz
,
Nicolson, Nancy A.
,
Marcus, Marco A. E.
in
Anesthesia
,
Anesthesiology
,
Anxiety
2018
The primary aim of the study was to assess the convergent validity of the Surgical Fear Questionnaire (SFQ) with other self-report instruments and biological indices of stress. Secondary aims were the examination of predictors of the level and time course of fear and preferences for fear treatment.
In a prospective observational cohort study SFQ short-term (SFQ-s) and long-term (SFQ-l) scores were assessed one week, one day, and the morning before cataract surgery, together with salivary cortisol and alpha-amylase (sAA) levels, and numeric rating scale (NRS) fear score. SFQ-scores were also assessed before second eye surgery. Expected pain and recovery, and sociodemographic and medico-psychological predictors of fear were assessed at baseline.
Data of 98 patients were analyzed. Scores of both SFQ-subscales (range 0-40) were generally low, all mean ≤ 9.0. SFQ-s and SFQ-l correlated significantly with the other self-report instruments: NRS fear .83 and .89, expected pain .49 and .54, expected recovery -.27 and -.44. No association was found between SFQ-scores and cortisol or sAA level. Predictors of the level of fear were baseline pain and stress. Additional effects of time were found for subgroups based on educational level, antidepressant use, and presurgical stress (SFQ-l). SFQ-scores were significantly lower before the second cataract surgery than before the first, and higher in patients who would have appreciated treatment of fear.
Convergent validity of the SFQ with other self-report measures is shown. The sensitivity of the SFQ permits the detection of small variations in fear caused by time or other factors.
Journal Article
The effect of Mindfulness-Based Stress Reduction on wound healing: a preliminary study
by
Peters, Madelon L
,
Yvo M C In den Bosch-Meevissen
,
Schepers, Jan
in
Adults
,
Cytokines
,
Exudates
2018
Psychological factors have been shown to influence the process of wound healing. This study examined the effect of Mindfulness-Based Stress Reduction (MBSR) on the speed of wound healing. The local production of pro-inflammatory cytokines and growth factors was studied as potential underlying mechanism. Forty-nine adults were randomly allocated to a waiting-list control group (n = 26) or an 8-week MBSR group (n = 23). Pre- and post-intervention/waiting period assessment for both groups consisted of questionnaires. Standardized skin wounds were induced on the forearm using a suction blister method. Primary outcomes were skin permeability and reduction in wound size monitored once a day at day 3, 4, 5, 6, 7, and 10 after injury. Secondary outcomes were cytokines and growth factors and were measured in wound exudates obtained at 3, 6, and 22 h after wounding. Although there was no overall condition effect on skin permeability or wound size, post hoc analyses indicated that larger increases in mindfulness were related to greater reductions in skin permeability 3 and 4 days after wound induction. In addition, MBSR was associated with lower levels of interleukin (IL)-8 and placental growth factor in the wound fluid 22 h after wound induction. These outcomes suggest that increasing mindfulness by MBSR might have beneficial effects on early stages of wound healing.
Journal Article
Cigarette smoking and reasons for leaving school among school dropouts in South Africa
2018
Background: School dropouts are those between 13-20 years old, have not completed their schooling and are not currently enrolled in school. School dropouts are at heightened risk of tobacco use and developing tobacco related disease and disability compared to in-school learners. The aim of this paper was to examine the relationship between reasons for leaving school and past month cigarette smoking, taking into account possible gender differences. Methods: Multiple logistic regression with gender as an effect moderator was used to analyse survey data from 4185 school dropouts. Province and area (urban, rural and peri - urban) were later incorporated into the analysis as possible effect moderators. Results: Past month cigarette smoking was reported by 50.4% of the respondents with boys (61.6%) smoking considerably more compared to girls (33.9%). We did not find any significant association between the reasons for leaving school and tobacco smoking when gender was tested as an effect moderator. However, dropping out of school for 'not being able to pay school fees', was found to be associated with less cigarette smoking, but only among girls residing in urban areas. Conclusions: Given the high prevalence of tobacco smoking among school dropouts, more research is needed to further explore the relationship between tobacco smoking and reasons for leaving school that were not considered in this study.
Journal Article
Cigarette smoking and reasons for leaving school among school dropouts in South Africa
2019
Background
School dropouts are at heightened risk of tobacco use compared to in-school learners. School dropouts are described as those not currently enrolled in school for the academic year, have not completed their schooling, and are between 13 and 20 years old. This paper examines the relationship between reasons for leaving school and past month cigarette smoking, taking into account gender differences.
Methods
Multiple logistic regression was used to analyse survey data (
n
= 4185). Geographical location was also incorporated into the analysis as effect moderators.
Results
Although no significant main effects between reasons for leaving school and tobacco use were found, results showed that those who leave school early smoke more. When examining interaction effects with gender, leaving school due to ‘not being able to pay for school fees’ was significantly associated with smoking, but only among girls residing in urban areas (OR = 0.327,
p
= .023)
.
Conclusions
More research is needed to understand why learners leave school and their subsequent tobacco use. This knowledge will help researchers identify and target those students that are at risk for dropping out of school and using tobacco.
Journal Article
Relationship Context Moderates Couple Congruence in Ratings of Sexual Arousal and Pain During Vaginal Sensations in the Laboratory
2019
Genital pain is a social experience that needs to be studied as a dyadic interaction between partners. The present study relied on a sample of 42 heterosexual couples to examine the level of congruence between both partners’ ratings of pain and sexual arousal in response to experimentally induced vaginal pressure that served as a simulation of vaginal sensations during penetration. We also inferred the men’s ability to estimate their partner’s level of pain and sexual arousal. Because the relationship has shown to influence pain estimations, we considered the moderating role of perceived partner responsiveness and relationship satisfaction. We found higher disagreement in pain ratings when vaginal pressure was induced in the context of a sexual film compared to a neutral film, with men overestimating the level of pain in women. Also sexual arousal ratings diverged between partners, with men underestimating their partners’ level of sexual arousal during the induction of vaginal pressure, regardless of whether they were watching a sexual or neutral film. Importantly, the level of congruence between actual and estimated ratings of pain and sexual arousal depended on how relationally satisfied men and women were and how validated and supported women felt by their male partner. These results make an important contribution to the growing literature on the social determinants of sexual pain experiences.
Journal Article
E-ReMI: Extended Maximal Interaction Two-mode Clustering
by
Ahmed, Zaheer
,
van Breukelen, Gerard
,
Cassese, Alberto
in
Bioinformatics
,
Classification
,
Clustering
2023
In this paper, we present E-ReMI, a new method for studying two-way interaction in row by column (i.e., two-mode) data. E-ReMI is based on a probabilistic two-mode clustering model that yields a two-mode partition of the data with maximal interaction between row and column clusters. The proposed model extends REMAXINT by allowing for unequal cluster sizes for the row clusters, thus introducing more flexibility in the model. In the manuscript, we use a conditional classification likelihood approach to derive the maximum likelihood estimates of the model parameters. We further introduce a test statistic for testing the null hypothesis of no interaction, discuss its properties and propose an algorithm to obtain its distribution under this null hypothesis. Free software to apply the methods described in this paper is developed in the R language. We assess the performance of the new method and compare it with competing methodologies through a simulation study. Finally, we present an application of the methodology using data from a study of person by situation interaction.
Journal Article
Round robin study of formalin-fixed paraffin-embedded tissues in mass spectrometry imaging
by
Buck, Achim
,
Heeren, Ron M A
,
Cassese, Alberto
in
Biological effects
,
Classifiers
,
Design of experiments
2018
Mass spectrometry imaging (MSI) has provided many results with translational character, which still have to be proven robust in large patient cohorts and across different centers. Although formalin-fixed paraffin-embedded (FFPE) specimens are most common in clinical practice, no MSI multicenter study has been reported for FFPE samples. Here, we report the results of the first round robin MSI study on FFPE tissues with the goal to investigate the consequences of inter- and intracenter technical variation on masking biological effects. A total of four centers were involved with similar MSI instrumentation and sample preparation equipment. A FFPE multi-organ tissue microarray containing eight different types of tissue was analyzed on a peptide and metabolite level, which enabled investigating different molecular and biological differences. Statistical analyses revealed that peptide intercenter variation was significantly lower and metabolite intercenter variation was significantly higher than the respective intracenter variations. When looking at relative univariate effects of mass signals with statistical discriminatory power, the metabolite data was more reproducible across centers compared to the peptide data. With respect to absolute effects (cross-center common intensity scale), multivariate classifiers were able to reach on average > 90% accuracy for peptides and > 80% for metabolites if trained with sufficient amount of cross-center data. Overall, our study showed that MSI data from FFPE samples could be reproduced to a high degree across centers. While metabolite data exhibited more reproducibility with respect to relative effects, peptide data-based classifiers were more directly transferable between centers and therefore more robust than expected.
Journal Article
Arc Spaces and Rogers-Ramanujan Identities
by
Bruschek, Clemens
,
Mourtada, Hussein
,
Schepers, Jan
in
[info.info-dm] computer science [cs]/discrete mathematics [cs.dm]
,
[math.math-co] mathematics [math]/combinatorics [math.co]
,
arc spaces
2011
Arc spaces have been introduced in algebraic geometry as a tool to study singularities but they show strong connections with combinatorics as well. Exploiting these relations we obtain a new approach to the classical Rogers-Ramanujan Identities. The linking object is the Hilbert-Poincaré series of the arc space over a point of the base variety. In the case of the double point this is precisely the generating series for the integer partitions without equal or consecutive parts. Les espaces des arcs ont été introduit pour étudier les singularités, mais ils ont aussi un lien fort avec la combinatoire. Ce lien permet une nouvelle approche vers les identités de Rogers-Ramanujan. L'objet permettant cette approche est la série de Hilbert-Poincaré de l'algèbre des arcs centrés en un point de la variété de base. Dans le cas où cette variété est le point double, cette série est la série génératrice des partitions d'un nombre entier sans parties égales ou consécutives.
Journal Article
Supporting Health Care Professionals to Improve the Processes of Shared Decision Making and Self-Management in a Web-Based Intervention: Randomized Controlled Trial
2014
Research to assess the effect of interventions to improve the processes of shared decision making and self-management directed at health care professionals is limited. Using the protocol of Intervention Mapping, a Web-based intervention directed at health care professionals was developed to complement and optimize health services in patient-centered care.
The objective of the Web-based intervention was to increase health care professionals' intention and encouraging behavior toward patient self-management, following cardiovascular risk management guidelines.
A randomized controlled trial was used to assess the effect of a theory-based intervention, using a pre-test and post-test design. The intervention website consisted of a module to help improve professionals' behavior, a module to increase patients' intention and risk-reduction behavior toward cardiovascular risk, and a parallel module with a support system for the health care professionals. Health care professionals (n=69) were recruited online and randomly allocated to the intervention group (n=26) or (waiting list) control group (n=43), and invited their patients to participate. The outcome was improved professional behavior toward health education, and was self-assessed through questionnaires based on the Theory of Planned Behavior. Social-cognitive determinants, intention and behavior were measured pre-intervention and at 1-year follow-up.
The module to improve professionals' behavior was used by 45% (19/42) of the health care professionals in the intervention group. The module to support the health professional in encouraging behavior toward patients was used by 48% (20/42). The module to improve patients' risk-reduction behavior was provided to 44% (24/54) of patients. In 1 of every 5 patients, the guideline for cardiovascular risk management was used. The Web-based intervention was poorly used. In the intervention group, no differences in social-cognitive determinants, intention and behavior were found for health care professionals, compared with the control group. We narrowed the intervention group and no significant differences were found in intention and behavior, except for barriers. Results showed a significant overall difference in barriers between the intervention and the control group (F1=4.128, P=.02).
The intervention was used by less than half of the participants and did not improve health care professionals' and patients' cardiovascular risk-reduction behavior. The website was not used intensively because of time and organizational constraints. Professionals in the intervention group experienced higher levels of barriers to encouraging patients, than professionals in the control group. No improvements were detected in the processes of shared decision making and patient self-management. Although participant education level was relatively high and the intervention was pre-tested, it is possible that the way the information was presented could be the reason for low participation and high dropout. Further research embedded in professionals' regular consultations with patients is required with specific emphasis on the processes of dissemination and implementation of innovations in patient-centered care.
Netherlands Trial Register Number (NTR): NTR2584; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2584 (Archived by WebCite at http://www.webcitation.org/6STirC66r).
Journal Article