| 1. |
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| 2. |
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| 3. |
- Cuéllar, J., et al.
(författare)
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The Molecular Chaperone CCT Sequesters Gelsolin and Protects it from Cleavage by Caspase-3: CCT-Gelsolin interaction may affect actin dynamics
- 2022
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836. ; 434:5
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Tidskriftsartikel (refereegranskat)abstract
- The actin filament severing and capping protein gelsolin plays an important role in modulation of actin filament dynamics by influencing the number of actin filament ends. During apoptosis, gelsolin becomes constitutively active due to cleavage by caspase-3. In non-apoptotic cells gelsolin is activated by the binding of Ca2+. This activated form of gelsolin binds to, but is not a folding substrate of the molecular chaperone CCT/TRiC. Here we demonstrate that in vitro, gelsolin is protected from cleavage by caspase-3 in the presence of CCT. Cryoelectron microscopy and single particle 3D reconstruction of the CCT:gelsolin complex reveals that gelsolin is located in the interior of the chaperonin cavity, with a placement distinct from that of the obligate CCT folding substrates actin and tubulin. In cultured mouse melanoma B16F1 cells, gelsolin co-localises with CCT upon stimulation of actin dynamics at peripheral regions during lamellipodia formation. These data indicate that localised sequestration of gelsolin by CCT may provide spatial control of actin filament dynamics. © 2021 The Authors
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| 4. |
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| 5. |
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| 6. |
- Berglund, U. W., et al.
(författare)
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Validation and development of MTH1 inhibitors for treatment of cancer
- 2016
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Ingår i: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 27:12, s. 2275-2283
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previously, we showed cancer cells rely on the MTH1 protein to prevent incorporation of otherwise deadly oxidised nucleotides into DNA and we developed MTH1 inhibitors which selectively kill cancer cells. Recently, several new and potent inhibitors of MTH1 were demonstrated to be non-toxic to cancer cells, challenging the utility of MTH1 inhibition as a target for cancer treatment. Material and methods: Human cancer cell lines were exposed in vitro to MTH1 inhibitors or depleted of MTH1 by siRNA or shRNA. 8-oxodG was measured by immunostaining and modified comet assay. Thermal Proteome profiling, proteomics, cellular thermal shift assays, kinase and CEREP panel were used for target engagement, mode of action and selectivity investigations of MTH1 inhibitors. Effect of MTH1 inhibition on tumour growth was explored in BRAF V600E-mutated malignant melanoma patient derived xenograft and human colon cancer SW480 and HCT116 xenograft models. Results: Here, we demonstrate that recently described MTH1 inhibitors, which fail to kill cancer cells, also fail to introduce the toxic oxidized nucleotides into DNA. We also describe a new MTH1 inhibitor TH1579, (Karonudib), an analogue of TH588, which is a potent, selective MTH1 inhibitor with good oral availability and demonstrates excellent pharmacokinetic and anti-cancer properties in vivo. Conclusion: We demonstrate that in order to kill cancer cells MTH1 inhibitors must also introduce oxidized nucleotides into DNA. Furthermore, we describe TH1579 as a best-in-class MTH1 inhibitor, which we expect to be useful in order to further validate the MTH1 inhibitor concept.
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| 7. |
- Jasilionis, Domantas, et al.
(författare)
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L’avant-garde en matière d’espérance de vie montre-t-elle la voie au reste de la population?
- 2014
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Ingår i: Population. - : CAIRN. - 0032-4663 .- 1957-7966. ; 69:4, s. 589-615
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Tidskriftsartikel (refereegranskat)abstract
- Do vanguard populations open new frontiers of survival and longevity that will eventually be reached by others? The main aim of this study is to identify the extent to which the non-vanguard populations in Finland, Norway, and Sweden might follow the mortality trajectories of the vanguard groups in these countries for different age ranges and for the major causes of death. The results show no systematic convergence between vanguard and non-vanguard sub-populations. On the contrary, they confirm the theory whereby each major epidemiological development initially gives rise to divergence in mortality trends. Our study found that at the sub-national level, rather than simply following (with a certain time lag) the same path as the vanguard groups, non-vanguard groups have their own pathways to low mortality which are related to specific determinants of mortality change. The study also found that a long time is needed for the non-vanguard group to attain the mortality levels already reached by the vanguard group at the start of the observation period. This is notably the case for the treatment and prevention of cardiovascular diseases.
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| 8. |
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| 9. |
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| 11. |
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| 12. |
- Bonagas, Nadilly, et al.
(författare)
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Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress
- 2022
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Ingår i: NATURE CANCER. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors. Helleday and colleagues describe a nanomolar MTHFD2 inhibitor that causes replication stress and DNA damage accumulation in cancer cells via thymidine depletion, demonstrating a potential therapeutic strategy in AML tumors in vivo.
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| 13. |
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| 14. |
- Datt, Gopal, et al.
(författare)
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Combined Bottom-Up and Top-Down Approach for Highly Ordered One-Dimensional Composite Nanostructures for Spin Insulatronics
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:31, s. 37490-37499
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Tidskriftsartikel (refereegranskat)abstract
- Engineering magnetic proximity effects-based devices requires developing efficient magnetic insulators. In particular, insulators, where magnetic phases show dramatic changes in texture on the nanometric level, could allow us to tune the proximity-induced exchange splitting at such distances. In this paper, we report the fabrication and characterization of highly ordered two-dimensional arrays of LaFeO3 (LFO)-CoFe2O4 (CFO) biphasic magnetic nanowires, grown on silicon substrates using a unique combination of bottom-up and top-down synthesis approaches. The regularity of the patterns was confirmed using atomic force microscopy and scanning electron microscopy techniques, whereas magnetic force microscopy images established the magnetic homogeneity of the patterned nanowires and absence of any magnetic debris between the wires. Transmission electron microscopy shows a close spatial correlation between the LFO and CFO phases, indicating strong grain-to-grain interfacial coupling, intrinsically different from the usual core-shell structures. Magnetic hysteresis loops reveal the ferrimagnetic nature of the composites up to room temperature and the presence of a strong magnetic coupling between the two phases, and electrical transport measurements demonstrate the strong insulating behavior of the LFO-CFO composite, which is found to be governed by Mottvariable range hopping conduction mechanisms. A shift in the Raman modes in the composite sample compared to those of pure CFO suggests the existence of strain-mediated elastic coupling between the two phases in the composite sample. Our work offers ordered composite nanowires with strong interfacial coupling between the two phases that can be directly integrated for developing multiphase spin insulatronic devices and emergent magnetic interfaces.
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| 15. |
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| 16. |
- Gad, Helge, et al.
(författare)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 17. |
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| 18. |
- Lövgren, Anna, et al.
(författare)
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The association between myofascial orofacial pain with and without referral and widespread pain
- 2022
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Ingår i: Acta Odontologica Scandinavica. - : Taylor & Francis. - 0001-6357 .- 1502-3850. ; 80:7, s. 481-486
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Pain referral on palpation has been suggested to be a clinical sign of central sensitization potentially associated with widespread pain conditions. Our aim was to evaluate if myofascial pain with referral is a better predictor for widespread pain when compared to no pain or local myofascial pain.Materials and methods: Individuals at the Public Dental services in Västerbotten, Sweden, were randomly invited based on their answers to three screening questions for temporomandibular disorders (TMD). In total, 300 individuals (202 women, 20–69 yrs) were recruited, and examined according to the Diagnostic Criteria for TMD (DC/TMD) after completion of a body pain drawing. Widespread pain was considered present when seven or more pain sites were reported on the widespread pain index. A binary logistic regression model, adjusted for the effect of age and gender were used to evaluate the association between myofascial orofacial pain and widespread pain.Results: Widespread pain was reported by 31.3% of the study sample. There was a 57.3% overlap with myofascial pain. Widespread pain was associated to myofascial orofacial pain with and myofascial orofacial pain (OR 4.83 95% CI 2.62–9.05 and OR 11.62 95% CI 5.18–27.88, respectively).Conclusion: These findings reinforce the existing knowledge on the overlap between painful TMD and other chronic pain conditions.
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| 19. |
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| 20. |
- Martin, D. M., et al.
(författare)
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Hydrophilic Wafer Bond Fabrication and Thermal Characterisation of new SOI Incorporating Buried Aluminium Nitride Insulator
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Annan publikation (populärvet., debatt m.m.)abstract
- Due to self heating effects of applications requiring high power dissipation in commercial SOI the need for alternative buried insulators such as aluminium nitride (AlN) is paramount. Here AlN films have been reactively sputtered with the smooth surfaces required for hydrophilic bonding. A bonding layer of amorphous silicon, -Si, has been sequentially sputtered with a surface roughness of 0.3 nm. A method of channelling the desorbed water and trapped gasses is presented with bond strength around 1.2 J/m2. Successful transfer of a silicon device layer is demonstrated onto a buried AlN insulator with a sheet resistance similar to original commercial specification. Electrical and thermal devices are fabricated in the device silicon using standard commercial MOS fabrication techniques. A thermal resistance of 47.5 K/W and 97 K/W is extracted for the new buried AlN insulator and commercial SOI, respectively. Thermal barriers hindering the full thermal properties of buried AlN are identified and solutions recommended
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| 21. |
- Muscas, Giuseppe, et al.
(författare)
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Ultralow magnetostrictive flexible ferromagnetic nanowires dagger
- 2021
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 13:12, s. 6043-6052
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Tidskriftsartikel (refereegranskat)abstract
- The integration of magneto-electric and spintronic sensors to flexible electronics presents a huge potential for advancing flexible and wearable technologies. Magnetic nanowires are core components for building such devices. Therefore, realizing flexible magnetic nanowires with engineered magneto-elastic properties is key to flexible spintronic circuits, as well as creating unique pathways to explore complex flexible spintronic, magnonic, and magneto-plasmonic devices. Here, we demonstrate highly resilient flexible ferromagnetic nanowires on transparent flexible substrates for the first time. Through extensive magneto-optical Kerr experiments, exploring the Villari effect, we reveal an ultralow magnetostrictive constant in nanowires, a two-order reduced value compared to bulk values. In addition, the flexible magnetic nanowires exhibit remarkable resilience sustaining bending radii similar to 5 mm, high endurance, and enhanced elastic limit compared to thin films of similar thickness and composition. The observed performance is corroborated by our micro-magnetic simulations and can be attributed to the reduced size and strong nanostructure-interfacial effects. Such stable magnetic nanowires with ultralow magnetostriction open up new opportunities for stable surface mountable and wearable spintronic sensors, advanced nanospintronic circuits, and for exploring novel strain-induced quantum effects in hybrid devices.
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| 22. |
- Pham, Ngan Hoang, et al.
(författare)
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High thermoelectric power factor of p-type amorphous silicon thin films dispersed with ultrafine silicon nanocrystals
- 2020
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 127:24
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Tidskriftsartikel (refereegranskat)abstract
- Silicon, a candidate as an abundant-element thermoelectric material for low-temperature thermal energy scavenging applications, generally suffers from rather low thermoelectric efficiency. One viable solution to enhancing the efficiency is to boost the power factor (PF) of amorphous silicon (a-Si) while keeping the thermal conductivity sufficiently low. In this work, we report that PF >1 m Wm−1 K−2 is achievable for boron-implanted p-type a-Si films dispersed with ultrafine crystals realized by annealing with temperatures ≤600 °C. Annealing at 550 °C initiates crystallization with sub-5-nm nanocrystals embedded in the a-Si matrix. The resultant thin films remain highly resistive and thus yield a low PF. Annealing at 600 °C approximately doubles the density of the sub-5-nm nanocrystals with a bimodal size distribution characteristic and accordingly reduces the fraction of the amorphous phase in the films. Consequently, a dramatically enhanced electrical conductivity up to 104 S/m and hence PF > 1 m Wm−1 K−2 measured at room temperature are achieved. The results show the great potential of silicon in large-scale thermoelectric applications and establish a route toward high-performance energy harvesting and cooling based on silicon thermoelectrics.
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| 23. |
- Rice, Amber M., et al.
(författare)
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Optimizing the trade-off between offspring number and quality in unpredictable environments: Testing the role of differential androgen transfer to collared flycatcher eggs
- 2013
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 1095-6867 .- 0018-506X. ; 63:5, s. 813-822
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Tidskriftsartikel (refereegranskat)abstract
- According to the brood reduction hypothesis, parents adjust their brood size in response to current environmental conditions. When resources are abundant, parents can successfully raise all hatched offspring, but when resources are scarce, brood reduction, i.e., the sacrifice of some siblings to secure the quality of a subset of offspring, may maximize fitness. Differential transfer of maternal androgens is one potential proximate mechanism through which female birds may facilitate brood reduction because it may alter the relative competitive ability of sibling nestlings. We tested the hypothesis that female collared flycatchers (Ficedula albicollis) manipulate sibling competition by transferring less androgens to eggs late in the laying sequence. We experimentally elevated androgen levels in i) whole clutches and ii) only the two last laid eggs, and compared growth and begging behavior of offspring from these treatments with a control treatment. By using three treatments and video assessment of begging, we examined the effects of within-clutch patterns of yolk androgen transfer on levels of sibling competition in situ. When androgens were elevated in only the two last laid eggs, begging was more even among siblings compared to control nests. We also found that female nestlings receiving additional yolk androgens showed higher mass gain later in the breeding season, while their male counterparts did not. Our results suggest that females may improve reproductive success in unpredictable environments by altering within-clutch patterns of yolk androgen transfer. We discuss the possibility that life-history divergence between the co-occurring collared and pied flycatcher (Ficedula hypoleuca) is amplified by patterns of yolk androgen transfer. (C) 2013 Elsevier Inc. All rights reserved.
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| 24. |
- Rybinski, Jakub, et al.
(författare)
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Competition-driven build-up of habitat isolation and selection favoring modified dispersal patterns in a young avian hybrid zone
- 2016
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 70:10, s. 2226-2238
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Tidskriftsartikel (refereegranskat)abstract
- Competition-driven evolution of habitat isolation is an important mechanism of ecological speciation but empirical support for this process is often indirect. We examined how an on-going displacement of pied flycatchers from their preferred breeding habitat by collared flycatchers in a young secondary contact zone is associated with (a) access to an important food resource (caterpillar larvae), (b) immigration of pied flycatchers in relation to habitat quality, and (c) the risk of hybridization in relation to habitat quality. Over the past 12 years, the estimated access to caterpillar larvae biomass in the habitat surrounding the nests of pied flycatchers has decreased by a fifth due to shifted establishment possibilities, especially for immigrants. However, breeding in the high quality habitat has become associated with such a high risk of hybridization for pied flycatchers that overall selection currently favors pied flycatchers that were forced to immigrate into the poorer habitats (despite lower access to preferred food items). Our results show that competition-driven habitat segregation can lead to fast habitat isolation, which per se caused an opportunity for selection to act in favor of future "voluntarily" altered immigration patterns and possibly strengthened habitat isolation through reinforcement.
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| 25. |
- Salehi, Amir M., et al.
(författare)
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Comparison of Preoperative Positron Emission Tomography/Computed Tomography with Panscopy and Ultrasound in Patients with Head and Neck Cancer
- 2020
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Ingår i: Oncology. - : S. Karger. - 0030-2414 .- 1423-0232. ; 98:12, s. 889-892
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: To compare data from preoperative positron emission tomography/computed tomography (PET/CT) with results of panscopy with biopsy and ultrasound with fine needle aspiration cytology (US-FNAC) on the same patients.Methods: In this retrospective (2014-2016) study, we compared PET/CT results with the results from panscopy with biopsy and US-FNAC in patients suspected of head and neck malignancy treated at the University Hospital in Umea, Sweden.Results: A 91.3% concordance was seen between results from PET/CT and panscopy with biopsy, whereas between PET/CT and US-FNAC the concordance was 89.1%.Conclusions: The present data show the usefulness of PET/CT in the diagnosis of head and neck malignancies.
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| 26. |
- Salehi, Amir M., et al.
(författare)
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Comparison of Quality of Life among Patients with Oro-Hypopharyngeal Cancer after Tonsillectomy and Panscopy Using Transoral Robotic Surgery : A Pilot Study
- 2020
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Ingår i: Case Reports in Oncology. - : S. Karger. - 1662-6575. ; 13:3, s. 1295-1303
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Tidskriftsartikel (refereegranskat)abstract
- Studies have shown lower treatment-related morbidity when using transoral robotic surgery (TORS) compared to conventional surgery. Patients investigated for oro- and hypopharyngeal cancer (T1, T2) were compared concerning quality of life (QoL) after tonsillectomy and TORS using validated QoL questionnaires: QLQ-C30 and QLQ-H&N35. The patients treated with TORS showed a higher pain score and thus also a higher need for painkillers, whereas they had lower values on self-assessment of anxiety/depression using the Hospital Anxiety and Depression Scale score. The pre- and postoperative information given did not meet the expectations of the patients treated with conventional surgery. The present data show advantages of the TORS technique from the patients' perspective. Even if patients treated with TORS are in need of more painkilling treatment, they cope better with the long-term effects of treatment, as judged by self-assessment of anxiety and depression.
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| 27. |
- Serrano, Ismael G., et al.
(författare)
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Two-Dimensional Flexible High Diffusive Spin Circuits
- 2019
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 19:2, s. 666-673
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Tidskriftsartikel (refereegranskat)abstract
- Owing to their unprecedented electronic properties, graphene and two-dimensional (2D) crystals have brought fresh opportunities for advances in planar spintronic devices. Graphene is an ideal medium for spin transport while being an exceptionally resilient material for flexible nanoelectronics. However, these extraordinary traits have never been combined to create flexible graphene spin circuits. Realizing such circuits could lead to bendable strain-spin sensors, as well as a unique platform to explore pure spin current based operations and low-power 2D flexible nanoelectronics. Here, we demonstrate graphene spin circuits on flexible substrates for the first time. Despite the rough topography of the flexible substrates, these circuits prepared with chemical vapor deposited monolayer graphene reveal an efficient room temperature spin transport with distinctively large spin diffusion coefficients ∼0.2 m2 s–1. Compared to earlier graphene devices on Si/SiO2 substrates, such values are up to 20 times larger, leading to one order higher spin signals and an enhanced spin diffusion length ∼10 μm in graphene-based nonlocal spin valves fabricated using industry standard systems. This high performance arising out of a characteristic substrate terrain shows promise of a scalable and flexible platform towards flexible 2D spintronics. Our innovation is a key step for the exploration of strain-dependent 2D spin phenomena and paves the way for flexible graphene spin memory–logic units and planar spin sensors.
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| 28. |
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| 29. |
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| 30. |
- Vallin, K S A, et al.
(författare)
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A new regioselective Heck vinylation with enamides. Synthesis and investigation of fluorous-tagged bidentate ligands for fast separation
- 2003
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Ingår i: Journal of Organic Chemistry. - Uppsala Univ, BMC, Dept Organ Pharmaceut Chem, SE-75123 Uppsala, Sweden. Univ Pittsburgh, Dept Chem, Pittsburgh, PA 15260 USA. : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 68:17, s. 6639-6645
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Tidskriftsartikel (refereegranskat)abstract
- Internal ligand-controlled Heck vinylations of enamides were performed with high regioselectivity and delivered moderate to good yields of dienamides. Controlled heating by microwave irradiation accelerated the palladium-catalyzed reactions, and full conversions were achieved after reaction times of only 15-30 min. New bidentate fluorous-tagged 1,3-bis(diphenylphosphino)propane ligands (F-dppp's) were synthesized and examined. The cationic vinylations of the enamides with F-dppp ligands rendered essentially the same alpha-selectivity and catalytic activity as in those vinylations where nonfluorous ligands were employed. After reaction, the fluorous-tagged ligand material was easily removed by convenient solid fluorous phase separation. The high selectivity, simplicity, and generality of the experimental procedure should make this approach to 2-acylamino-1,3-butadienes attractive.
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| 31. |
- Vallin, K S A, et al.
(författare)
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Aqueous DMF-potassium carbonate as a substitute for thallium and silver additives in the palladium-catalyzed conversion of aryl bromides to acetyl arenes
- 2001
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Ingår i: Journal of Organic Chemistry. - Uppsala Univ, Dept Organ Pharmaceut Chem, BMC, SE-75123 Uppsala, Sweden. : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 66:12, s. 4340-4343
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Tidskriftsartikel (refereegranskat)abstract
- Highly selective palladium-catalyzed internal alpha -arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.
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| 32. |
- Vallin, K S A, et al.
(författare)
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High-speed Heck reactions in ionic liquid with controlled microwave heating
- 2002
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Ingår i: Journal of Organic Chemistry. - Uppsala Univ, BMC, Dept Organ Pharmaceut Chem, SE-75123 Uppsala, Sweden. : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 67:17, s. 6243-6246
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Tidskriftsartikel (refereegranskat)abstract
- Palladium-catalyzed Heck arylations in the polar and robust ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF(6)), have for the first time been accomplished under microwave irradiation. The couplings were efficiently performed in sealed tubes within 5-45 min of heating. Without significant reductions in yield, a phosphine-free ionic catalyst phase could be recycled in five successive 20 min reactions at 180 degreesC. The product was easily removed from the reaction medium by distillation.
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| 33. |
- Vallin, K S A, et al.
(författare)
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Highly selective palladium-catalyzed synthesis of protected alpha,beta-unsaturated methyl ketones and 2-alkoxy-1,3-butadienes. High-speed chemistry by microwave flash heating
- 2000
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Ingår i: Journal of Organic Chemistry. - Uppsala Univ, Uppsala Biomed Ctr, Dept Organ Pharmaceut Chem, SE-75123 Uppsala, Sweden. : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 65:15, s. 4537-4542
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Tidskriftsartikel (refereegranskat)abstract
- A selective and mild procedure is described for the direct synthesis of 2-alkene-2-methyl-1,3-dioxolanes via regiocontrolled Heck vinylation of commercially available 2-hydroxyethyl vinyl ether. The procedure permits chemoselective transformation of a vinylic triflate or bromide into a blocked alpha,beta-unsaturated methyl ketone. Furthermore, a significantly improved and highly regioselective synthesis of 2-alkoxy-1,3-butadienes has been developed. Flash heating by microwave irradiation promotes the palladium-catalyzed reactions, and the starting materials are fully converted after reaction times of 5-7 min.
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| 34. |
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| 35. |
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| 36. |
- Vallin, Niclas, et al.
(författare)
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Combined effects of interspecific competition and hybridization impede local coexistence of Ficedula flycatchers
- 2012
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 26:4, s. 927-942
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Tidskriftsartikel (refereegranskat)abstract
- At secondary contact closely related species may both compete over similar resources and/or hybridize. Simulation models suggest that hybridization increases the risk of extinction beyond the risk resulting from interspecific competition alone, but such combined effects are rarely studied empirically. Here, we use detailed records on pairing patterns, breeding success, local recruitment and immigration collected during 8 years (2002-2009) to investigate the underlying mechanism of the rapid displacement of pied flycatchers by collared flycatchers on the Swedish island of A-land. We found no differences in average reproductive success or reproductive lifespan between the two species. However, we show that young male pied flycatchers failed to establish new territories as the density of male collared flycatchers increased. In addition, as the relative frequency of collared flycatchers increased, the risk of hybridization dramatically increased for female pied flycatchers, which speeds up the exclusion process since there is a high fitness cost associated with hybridization between the two species. In a nearby control area, within the same island, where pied flycatchers breed in the absence of collared flycatchers, no decline in the number of breeding pairs was observed during the same period of time. Our results demonstrate the crucial importance of studying the combined effects of various types of heterospecific interactions to understand and predict the ecological and evolutionary implications of secondary contact between congeneric species. These findings are particularly interesting in the light of recent climate change since the expected range shifts of many taxa will increase competitive and sexual interactions between previously separated species.
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| 37. |
- Vallin, Niclas, et al.
(författare)
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Positive feedback between ecological and reproductive character displacement in a young avian hybrid zone
- 2012
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 66:4, s. 1167-1179
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Tidskriftsartikel (refereegranskat)abstract
- Character displacement can reduce costly interspecific interactions between young species. We investigated the mechanisms behind divergence in three key traits—breeding habitat choice, timing of breeding, and plumage coloration—in Ficedula flycatchers. We found that male pied flycatchers became expelled from the preferred deciduous habitat into mixed forest as the superior competitor, collared flycatchers, increased in numbers. The peak in food abundance differs between habitats, and the spatial segregation was paralleled by an increased divergence in timing of breeding between the two species. Male pied flycatchers vary from brown to black with brown coloration being more frequent in sympatry with collared flycatchers, a pattern often proposed to result from selection against hybridization, that is, reinforcement. In contrast to this view, we show that brown male pied flycatchers more often hybridize than black males. Male pied flycatcher plumage coloration influenced the territory obtained in areas of co-occurrence with collared flycatchers, and brown male pied flycatchers experienced higher relative fitness than black males when faced with heterospecific competition. We suggest that allopatric divergence in resource defense ability causes a feedback loop at secondary contact where male pied flycatchers with the most divergent strategy compared to collared flycatchers are favored by selection.
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| 38. |
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