| 1. |
- James, John R., et al.
(författare)
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The T Cell Receptor Triggering Apparatus Is Composed of Monovalent or Monomeric Proteins
- 2011
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology, Inc.. - 0021-9258 .- 1083-351X. ; 286:37, s. 31993-32001
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the component stoichiometry of the T cell antigen receptor (TCR) triggering apparatus is essential for building realistic models of signal initiation. Recent studies suggesting that the TCR and other signaling-associated proteins are preclustered on resting T cells relied on measurements of the behavior of membrane proteins at interfaces with functionalized glass surfaces. Using fluorescence recovery after photo-bleaching, we show that, compared with the apical surface, the mobility of TCRs is significantly reduced at Jurkat T cell/glass interfaces, in a signaling-sensitive manner. Using two biophysical approaches that mitigate these effects, bioluminescence resonance energy transfer and two-color coincidence detection microscopy, we show that, within the uncertainty of the methods, the membrane components of the TCR triggering apparatus, i.e. the TCR complex, MHC molecules, CD4/Lck and CD45, are exclusively monovalent or monomeric in human T cell lines, implying that TCR triggering depends only on the kinetics of TCR/pMHC interactions. These analyses also showed that constraining proteins to two dimensions at the cell surface greatly enhances random interactions versus those between the membrane and the cytoplasm. Simulations of TCR-pMHC complex formation based on these findings suggest how unclustered TCR triggering-associated proteins might nevertheless be capable of generating complex signaling outputs via the differential recruitment of cytosolic effectors to the cell membrane.
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| 2. |
- Kia, Richard, et al.
(författare)
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MicroRNA-122 : a novel hepatocyte-enriched in vitro marker of drug-induced cellular toxicity
- 2015
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Ingår i: Toxicological Sciences. - : Oxford University Press. - 1096-6080 .- 1096-0929. ; 144:1, s. 173-185
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Tidskriftsartikel (refereegranskat)abstract
- Emerging hepatic models for the study of drug-induced toxicity include pluripotent stem cell-derived hepatocyte-like cells (HLCs) and complex hepatocyte-non-parenchymal cellular coculture to mimic the complex multicellular interactions that recapitulate the niche environment in the human liver. However, a specific marker of hepatocyte perturbation, required to discriminate hepatocyte damage from non-specific cellular toxicity contributed by non-hepatocyte cell types or immature differentiated cells is currently lacking, as the cytotoxicity assays routinely used in in vitro toxicology research depend on intracellular molecules which are ubiquitously present in all eukaryotic cell types. In this study, we demonstrate that microRNA-122 (miR-122) detection in cell culture media can be used as a hepatocyte-enriched in vitro marker of drug-induced toxicity in homogeneous cultures of hepatic cells, and a cell-specific marker of toxicity of hepatic cells in heterogeneous cultures such as HLCs generated from various differentiation protocols and pluripotent stem cell lines, where conventional cytotoxicity assays using generic cellular markers may not be appropriate. We show that the sensitivity of the miR-122 cytotoxicity assay is similar to conventional assays that measure lactate dehydrogenase activity and intracellular adenosine triphosphate when applied in hepatic models with high levels of intracellular miR-122, and can be multiplexed with other assays. MiR-122 as a biomarker also has the potential to bridge results in in vitro experiments to in vivo animal models and human samples using the same assay, and to link findings from clinical studies in determining the relevance of in vitro models being developed for the study of drug-induced liver injury.
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| 3. |
- Preece, David A., et al.
(författare)
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Alexithymia and emotion regulation
- 2023
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Ingår i: Journal of Affective Disorders. - : Elsevier. - 0165-0327 .- 1573-2517. ; 324, s. 232-238
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundAlexithymia is a key transdiagnostic risk factor for emotion-based psychopathologies. Conceptual models specify that this is because alexithymia impairs emotion regulation. However, the extent of these putative emotion regulation impairments remains underexplored. Our aim in this study was to begin to address this gap by examining whether people with high, average, or low levels of alexithymia differ in the types of emotion regulation strategies they typically use.MethodGeneral community adults from the United States (N = 501) completed a battery of alexithymia and emotion regulation measures. Participants were grouped into high, average, and low alexithymia quantiles.ResultsAfter controlling for demographics and current levels of distress, the high, average, and low alexithymia groups differed in their use of cognitive and behavioral emotion regulation strategies. Compared to the other groups, the high alexithymia group reported lesser use of generally adaptive regulation strategies (cognitive reappraisal, approaching problems, and seeking social support) and greater use of generally maladaptive regulation strategies (expressive suppression, behavioral withdrawal, ignoring).LimitationsOur data were cross-sectional and from self-report questionnaires. Future work in other cultural groups would be beneficial.ConclusionsOur results support the view that alexithymia is associated with impaired emotion regulation. In particular, people with high alexithymia seem to exhibit a less adaptive profile of emotion regulation strategies. Direct targeting of these emotion regulation patterns in psychotherapy may therefore be a useful pathway for the treatment of emotional disorder symptoms in people with high alexithymia.
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| 4. |
- Preece, David A., et al.
(författare)
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Alexithymia or general psychological distress? : Discriminant validity of the Toronto Alexithymia Scale and the Perth Alexithymia Questionnaire
- 2024
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Ingår i: Journal of Affective Disorders. - : Elsevier. - 0165-0327 .- 1573-2517. ; 352, s. 140-145
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Tidskriftsartikel (refereegranskat)abstract
- Background: Alexithymia is an important transdiagnostic risk factor for emotion-based psychopathologies. However, it remains unclear whether alexithymia questionnaires actually measure alexithymia, or whether they measure emotional distress. Our aim here was to address this discriminant validity concern via exploratory factor analysis (EFA) of the 20-item Toronto Alexithymia Scale (TAS-20) and the Perth Alexithymia Questionnaire (PAQ). Method: United States general community adults (N = 508) completed the TAS-20, PAQ, and the Depression Anxiety Stress Scales-21 (DASS-21). EFA was used to examine the latent dimensions underlying these measures' scores. Results: Our EFA extracted two higher-order factors, an “alexithymia” factor and a “general distress” factor (i.e., depression, anxiety, stress). All PAQ scores loaded cleanly on the alexithymia factor, with no cross-loadings on the distress factor. However, for the TAS-20, Difficulty Identifying Feelings (DIF) facet scores cross-loaded highly on the distress factor. Limitations: Our sample consisted of general community adults; future work in clinical settings will be useful. Conclusions: Our data indicate that the PAQ has good discriminant validity. However, the TAS-20 appears to have significant discriminant validity problems, in that much of the variance in its DIF facet reflects people's current levels of distress, rather than alexithymia. The TAS-20, which has traditionally been the most widely used alexithymia questionnaire, may therefore not be the optimal alexithymia tool. Our findings add to the body of evidence supporting the validity and utility of the PAQ and suggest that, moving forward, it is a superior option to the TAS-20 for alexithymia assessments.
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| 5. |
- Preece, David A., et al.
(författare)
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The Perth Alexithymia Questionnaire-Short Form (PAQ-S) : A 6-item measure of alexithymia
- 2023
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Ingår i: Journal of Affective Disorders. - : Elsevier. - 0165-0327 .- 1573-2517. ; 325, s. 493-501
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Alexithymia is a trait characterized by difficulties identifying feelings, difficulties describing feelings, and externally orientated thinking. It is widely regarded as an important transdiagnostic risk factor for a range of psychopathologies, including depressive and anxiety disorders. Whilst several well-validated psychometric measures of alexithymia exist, these are relatively lengthy, thus limiting their utility in time-pressured settings. In this paper, we address this gap by introducing and validating a brief 6-item version of the Perth Alexithymia Questionnaire, called the Perth Alexithymia Questionnaire-Short Form (PAQ-S). METHOD: Across two studies with adult samples (Study 1 N = 508 United States community; Study 2 = 378 Australian college students), we examined the psychometric properties of the PAQ-S in terms of its factor structure, reliability, and concurrent/criterion validity. RESULTS: In exploratory and confirmatory factor analyses, all PAQ-S items loaded well on a single general alexithymia factor. The PAQ-S total score had high reliability, and correlated as expected with the long-form of the PAQ, as well as other established markers of alexithymia, emotion regulation, and affective disorder symptoms. LIMITATIONS: Our samples were general community or college student samples from two Western countries; future validation work in clinical samples and more diverse cultural groups is thus needed. CONCLUSIONS: The PAQ-S retains the psychometric strengths of the PAQ. As such, the PAQ-S can be used as a quick, robust measure of overall alexithymia levels. The introduction of the PAQ-S hence enables valid assessments of alexithymia in a more diverse range of settings and research designs.
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