| 1. |
- Laursen, Louise, 1988-
(author)
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Exploring the Role of the PDZ Domain in a Supramodule
- 2021
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Doctoral thesis (other academic/artistic)abstract
- The postsynaptic density (PSD) is a large, dense and membraneless compartment of proteins associated below the postsynaptic membrane bilayer, and which constantly undergoes morphological alteration in response to synaptic activity. Formation of PSD is associated with liquid-liquid phase separation of scaffold proteins in complex with other PSD proteins. PSD-95, one of the most abundant scaffold proteins, contains five domains: PDZ1, PDZ2, PDZ3, Src homology 3 (SH3), and guanylate kinase-like (GK) domain. The domains are functionally divided in two supramodules: PDZ1-PDZ2 and PDZ3-SH3-GK (PSG). Multi-domain proteins are characterized through their isolated domains in most studies and represented by “beads on a string” model, which means that the function of a single domain is independent of the context. In this thesis, the properties of PDZ3 and PSG are compared to elucidate how and when PSD-95 can been characterized by the simple “beads on a string” model. Kinetic characterization of CRIPT binding to PDZ3 showed a two-state mechanism, but a more complex mechanism involving two conformational states upon binding to PSG. The results were consistent with recent structural findings of conformational changes in PSD-95, altogether showing that conformational transitions in supertertiary structures can shape the ligand-binding energy landscape and modulate protein-protein interactions. Next the allosteric networks in a PDZ:ligand complex were experimentally mapped, both in isolation and in the context of a supramodular structure. Data showed that allosteric networks in a PDZ3 domain has high dependency on the supertertiary structure. Furthermore, equilibrium and kinetic folding experiments were applied to demonstrate that the PDZ3 domain folds faster and independently from the SH3-GK tandem, which folds as one cooperative unit. However, concurrent folding of the PDZ3 domain slows down folding of SH3-GK by non-native interactions, resulting in an off-pathway folding intermediate. Finally, the interactome of PSG in PSD was mapped. PDZ3 and PSG show high specificity for peptides with type I PBM. Interestingly, two proteins called SynGap and AGRB1 only bind with high affinity to PSG and forms concentration dependent liquid droplets. The results show how context in terms of supertertiary structure alter affinity and function, and suggest a model for how PSD anchor to the postsynaptic membrane. Altogether, the findings in the thesis show that binding energy landscape, interactome, allosteric network, folding mechanism and phase separation are dependent on the context, which suggest that we need to be careful in interpretation of data obtained from isolated domains in multi-domain proteins.
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| 2. |
- Eriksson, Mikael, et al.
(author)
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Low-Dose Tamoxifen for Mammographic Density Reduction : A Randomized Controlled Trial
- 2021
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In: Journal of Clinical Oncology. - 0732-183X. ; 39:17, s. 1899-
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Journal article (peer-reviewed)abstract
- PURPOSE: Tamoxifen prevents breast cancer in high-risk women and reduces mortality in the adjuvant setting. Mammographic density change is a proxy for tamoxifen therapy response. We tested whether lower doses of tamoxifen were noninferior to reduce mammographic density and associated with fewer symptoms.PATIENTS AND METHODS: Women, 40-74 years of age, participating in the Swedish mammography screening program were invited to the 6-month double-blind six-arm randomized placebo-controlled noninferiority dose-determination KARISMA phase II trial stratified by menopausal status (EudraCT 2016-000882-22). In all, 1,439 women were accrued with 1,230 participants accessible for intention-to-treat analysis. The primary outcome was proportion of women treated with placebo, 1, 2.5, 5, and 10 mg whose mammographic density decreased at least as much as the median reduction in the 20 mg arm. The noninferior margin was 17%. Secondary outcome was reduction of symptoms. Post hoc analyses were performed by menopausal status. Per-protocol population and full population were analyzed in sensitivity analysis.RESULTS: The 1,439 participants, 566 and 873 pre- and postmenopausal women, respectively, were recruited between October 1, 2016, and September 30, 2019. The participants had noninferior mammographic density reduction following 2.5, 5, and 10 mg tamoxifen compared with the median 10.1% decrease observed in the 20 mg group, a reduction confined to premenopausal women. Severe vasomotor symptoms (hot flashes, cold sweats, and night sweats) were reduced by approximately 50% in the 2.5, 5, and 10 mg groups compared with the 20 mg group.CONCLUSION: Premenopausal women showed noninferior magnitude of breast density decrease at 2.5 mg of tamoxifen, but fewer side effects compared with the standard dose of 20 mg. Future studies should test whether 2.5 mg of tamoxifen reduces the risk of primary breast cancer.
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| 4. |
- Hammarström, Sofia, 1984-
(author)
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Identification of young people at risk of sexual ill health : implementing a new tool in youth clinics
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Background: Young people are at increased risk of sexual ill health in terms of sexually transmitted infections, unintended pregnancy, and sexual violence. There is limited knowledge of evidence-based preventive practices for identification of young people at risk of sexual ill health when in contact with health care. Aims: The overall aim of this thesis was to generate new knowledge concerning how Swedish youth clinics can work systematically to identify young people at risk of sexual ill health or who have negative sexual experiences. Specific objectives were to develop a risk-assessment model for the identification of youth at risk of contracting chlamydia; to develop and pilot-implement an evidence-informed tool for identifying young people at risk of sexual ill health in terms of sexually transmitted infections, unintended pregnancies, and sexual violence at Swedish youth clinics; and to explore youth clinic visitors’ and staff’s experiences of using that tool. Methods: The thesis takes a mixed methods approach and includes four studies. First, data from a national sample of sexually active young people, aged 15–24 years (n=6544), were used to develop a risk-assessment model for chlamydia infection. Second, a risk-assessment tool (SEXual health Identification Tool; SEXIT) was developed and pilot-implemented at three youth clinics for 1 month. The tool includes three components: (1) staff training; (2) a questionnaire for youth clinic visitors; and (3) a written guide for staff to support the subsequent dialogue and risk assessment based on the questionnaire. Questionnaire data from visitors (n=268) and staff (n=18) were analysed. Third, youth clinic visitors’ experiences were explored in 20 interviews with visitors (15–24 years) from the participating youth clinics. Fourth, staff’s experiences of working with SEXIT were investigated in four focus group discussions (n=16). Quantitative and qualitative methods were used for data analyses. Results: The risk-assessment model demonstrated that the distribution of chlamydia is skewed; 38% of cases were estimated to occur among a tenth of the population. Women most at risk of chlamydia were best identified using the variables age, number of sexual partners in the past year, and experience of sex for reimbursement. The corresponding variables for men were age, number of sexual partners, and alcohol use. SEXIT was validated and pilot-implemented at three youth clinics (response rate 86%). Before implementation, all staff perceived a need for more systematic screening for sexual risk-taking and sexual ill health at youth clinics. Youth clinic visitors demonstrated between 0 and 7 parallel risk factors. Staff experienced that using SEXIT systematically increased the consistency and quality of the clinics’ work, and youth clinic visitors reported that the questions were important and not uncomfortable or difficult. The visitors explained that questions in a written format followed by a dialogue initiated by the youth clinic staff enabled disclosure of negative experiences. Conclusions: The risk-assessment model demonstrates that the number of partners during the past year is the most important risk factor for chlamydia regardless of gender. SEXIT is an acceptable, appropriate, and feasible tool from the perspective of youth clinic staff, youth clinic visitors, and from an implementation point of view. Using the tool systematically may help raise important questions on sexual risk-taking and sexual ill health with youth clinic visitors and identify visitors with multiple risk factors. Being asked the sensitive yet important questions in SEXIT, followed by a respectful and non-judgemental conversation led by the youth clinic staff, has the potential to open up a more in depth and broader dialogue about the visitors’ sexual health. The systematic procedure helps youths feel that they are taken seriously and instils a feeling of trust that enables disclosure of sensitive experiences. From the staff perspective, SEXIT facilitates identification of young people exposed to or at risk of sexual ill health by simplifying and ensuring consistency and quality in their work.
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| 5. |
- Hammarström, Sofia, 1984-, et al.
(author)
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Staff's experiences of a pilot implementation of the SEXual health Identification Tool for assessing sexual ill health among visitors to Swedish youth clinics: A focus group study
- 2021
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In: Sexual and Reproductive Healthcare. - : Elsevier BV. - 1877-5756 .- 1877-5764. ; 29
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Journal article (peer-reviewed)abstract
- Background: Young people are disproportionally burdened by sexual ill health. The SEXual health Identification Tool (SEXIT) was developed for use at youth clinics, to facilitate identification of visitors exposed to or at risk of sexual ill health. The aim of this study was to explore experiences of using SEXIT among youth clinic staff who participated in a pilot implementation, with a focus on usefulness, implementation determinants, and feasibility of implementing SEXIT at Swedish youth clinics. Methods: Four focus group discussions were conducted with youth clinic staff from three clinics. The clinics had used SEXIT systematically in consultations with all visitors for one month. Data were analysed using qualitative analysis designed for focus groups. Results: Most participants experienced that the SEXIT routines were well functioning and that using SEXIT gave a comprehensive picture of the visitor and resulted in more concrete answers, which facilitated the risk assessment. The medical staff experienced that they identified more youth at risk with SEXIT, while the psychosocial staff were less convinced. Existing challenges related to the routines at the clinics and heavy workload during drop-in hours. Conclusions: Staff experience SEXIT as useful for identifying young people exposed to or at risk of sexual ill health. Systematic use ensures consistency and quality in assessing the visitors, which may facilitate implementation. The use of SEXIT is challenged by heavy workload, conflicting routines, and the experience that some visitors identified through SEXIT decline further care. Implementation of SEXIT in Swedish youth clinics is considered feasible. © 2021
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| 6. |
- Lindberg, Anton, et al.
(author)
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Radiosynthesis, In Vitro and In Vivo Evaluation of [F-18]CBD-2115 as a First-in-Class Radiotracer for Imaging 4R-Tauopathies
- 2021
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In: ACS Chemical Neuroscience. - : AMER CHEMICAL SOC. - 1948-7193. ; 12:4, s. 596-602
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Journal article (peer-reviewed)abstract
- CBD-2115 was selected from a library of 148 compounds based on a pyridinyl-indole scaffold as a first-in-class 4R-tau radiotracer. In vitro binding assays showed [H-3]CBD-2115 had a K-D value of 6.9 nM and a nominal B-max of 500 nM in 4R-tau expressing P301L transgenic mouse tissue. In binding assays with human brain tissue homogenates, [H-3]CBD-2115 has a higher affinity (4.9 nM) for progressive supranuclear palsy specific 4R-tau deposits than [H-3]flortaucipir (45 nM) or [H-3]MK-6240 (>50 nM). [F-18]CBD-2115 was reliably synthesized (3-11% radiochemical yield with molar activity of 27-111 GBq/mu mol and >97% radiochemical purity). Dynamic PET imaging was conducted in mice, rats, and nonhuman primates, and all species showed initial brain uptake of 0.5-0.65 standardized uptake value with fast clearance from normal tissues. [H-3]CBD-2115 could be a useful lead radioligand for further research in 4R-tauopathies, and PET radiotracer development will focus on improving brain uptake and binding affinity.
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| 7. |
- Liu, He, et al.
(author)
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Distinct conformers of amyloid beta accumulate in the neocortex of patients with rapidly progressive Alzheimers disease
- 2021
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In: Journal of Biological Chemistry. - : Elsevier. - 0021-9258 .- 1083-351X. ; 297:5
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Journal article (peer-reviewed)abstract
- Amyloid beta (A beta) deposition in the neocortex is a major hallmark of Alzheimers disease (AD), but the extent of deposition does not readily explain phenotypic diversity and rate of disease progression. The prion strain-like model of disease heterogeneity suggests the existence of different conformers of A beta. We explored this paradigm using conformation-dependent immunoassay (CDI) for A beta and conformation-sensitive luminescent conjugated oligothiophenes (LCOs) in AD cases with variable progression rates. Mapping the A beta conformations in the frontal, occipital, and temporal regions in 20 AD patients with CDI revealed extensive interindividual and anatomical diversity in the structural organization of A beta with the most significant differences in the temporal cortex of rapidly progressive AD. The fluorescence emission spectra collected in situ from A beta plaques in the same regions demonstrated considerable diversity of spectral characteristics of two LCOs-quatroformylthiophene acetic acid and heptaformylthiophene acetic acid. Heptaformylthiophene acetic acid detected a wider range of A beta deposits, and both LCOs revealed distinct spectral attributes of diffuse and cored plaques in the temporal cortex of rapidly and slowly progressive AD and less frequent and discernible differences in the frontal and occipital cortex. These and CDI findings indicate a major conformational diversity of A beta accumulating in the neocortex, with the most notable differences in temporal cortex of cases with shorter disease duration, and implicate distinct A beta conformers (strains) in the rapid progression of AD.
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| 8. |
- Mezheyeuski, Artur, et al.
(author)
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The Immune Landscape of Colorectal Cancer
- 2021
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In: Cancers. - : MDPI. - 2072-6694. ; 13:21
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Journal article (peer-reviewed)abstract
- We sought to provide a detailed overview of the immune landscape of colorectal cancer in the largest study to date in terms of patient numbers and analyzed immune cell types. We applied a multiplex in situ staining method in combination with an advanced scanning and image analysis pipeline akin to flow cytometry, and analyzed 5968 individual multi-layer images of tissue defining in a total of 39,078,450 cells. We considered the location of immune cells with respect to the stroma, and tumor cell compartment and tumor regions in the central part or the invasive margin. To the best of our knowledge, this study is the first comprehensive spatial description of the immune landscape in colorectal cancer using a large population-based cohort and a multiplex immune cell identification.While the clinical importance of CD8+ and CD3+ cells in colorectal cancer (CRC) is well established, the impact of other immune cell subsets is less well described. We sought to provide a detailed overview of the immune landscape of CRC in the largest study to date in terms of patient numbers and in situ analyzed immune cell types. Tissue microarrays from 536 patients were stained using multiplexed immunofluorescence panels, and fifteen immune cell subclasses, representing adaptive and innate immunity, were analyzed. Overall, therapy-naive CRC patients clustered into an 'inflamed' and a 'desert' group. Most T cell subsets and M2 macrophages were enriched in the right colon (p-values 0.046-0.004), while pDC cells were in the rectum (p = 0.008). Elderly patients had higher infiltration of M2 macrophages (p = 0.024). CD8+ cells were linked to improved survival in colon cancer stages I-III (q = 0.014), while CD4+ cells had the strongest impact on overall survival in metastatic CRC (q = 0.031). Finally, we demonstrated repopulation of the immune infiltrate in rectal tumors post radiation, following an initial radiation-induced depletion. This study provides a detailed analysis of the in situ immune landscape of CRC paving the way for better diagnostics and providing hints to better target the immune microenvironment.
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| 9. |
- Pourrahimi, Amir Masoud, 1985, et al.
(author)
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Repurposing Poly(3-hexylthiophene) as a Conductivity-Reducing Additive for Polyethylene-Based High-Voltage Insulation
- 2021
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In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 33:27
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Journal article (peer-reviewed)abstract
- Poly(3-hexylthiophene) (P3HT) is found to be a highly effective conductivity-reducing additive for low-density polyethylene (LDPE), which introduces a new application area to the field of conjugated polymers. Additives that reduce the direct-current (DC) electrical conductivity of an insulation material at high electric fields have gained a lot of research interest because they may facilitate the design of more efficient high-voltage direct-current power cables. An ultralow concentration of regio-regular P3HT of 0.0005 wt% is found to reduce the DC conductivity of LDPE threefold, which translates into the highest efficiency reported for any conductivity-reducing additive to date. The here-established approach, i.e., the use of a conjugated polymer as a mere additive, may boost demand in absolute terms beyond the quantities needed for thin-film electronics, which would turn organic semiconductors from a niche product into commodity chemicals.
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