| 291. |
- Bivall Persson, Petter, 1979-, et al.
(författare)
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Improved Feature Detection over Large Force Ranges Using History Dependent Transfer Functions
- 2009
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Ingår i: Third Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, WorldHaptics 2009. - : IEEE. - 9781424438587 ; , s. 476-481
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a history dependent transfer function (HDTF) as a possible approach to enable improved haptic feature detection in high dynamic range (HDR) volume data. The HDTF is a multi-dimensional transfer function that uses the recent force history as a selection criterion to switch between transfer functions, thereby adapting to the explored force range. The HDTF has been evaluated using artificial test data and in a realistic application example, with the HDTF applied to haptic protein-ligand docking. Biochemistry experts performed docking tests, and expressed that the HDTF delivers the expected feedback across a large force magnitude range, conveying both weak attractive and strong repulsive protein-ligand interaction forces. Feature detection tests have been performed with positive results, indicating that the HDTF improves the ability of feature detection in HDR volume data as compared to a static transfer function covering the same range.
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| 292. |
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| 293. |
- Bjartell, Anders, et al.
(författare)
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Prediction of clinical progression after radical prostatectomy in a nationwide population-based cohort
- 2016
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Ingår i: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1805 .- 2168-1813. ; 50:4, s. 255-259
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this study was to create a model for predicting progression-free survival after radical prostatectomy for localized prostate cancer. Material and methods: The risk of biochemical recurrence (BCR) was modelled in a cohort of 3452 men aged 70 years or younger who were primarily treated with radical prostatectomy after being diagnosed between 2003 and 2006 with localized prostate cancer [clinical stage T1c-T2, Gleason score 5-10, N0/NX, M0/MX, prostate-specific antigen (PSA)<20 ng/ml]. The cohort was split into two: one cohort for model development (n = 3452) and one for validation (n = 1762). BCR was defined as two increasing PSA values of at least 0.2 ng/ml, initiation of secondary therapy, distant metastases or death from prostate cancer. Multivariable Cox proportional hazard regression was applied, predictive performance was assessed using the bootstrap resampling technique to calculate the c index, and calibration of the model was evaluated by comparing predicted and observed Kaplan-Meier 1 year BCR. Results: The overall 5 year progression-free survival was 83% after a median follow-up time of 6.8 years in the development cohort and 7.3 years in the validation cohort. The final model included T stage, PSA level, primary and secondary Gleason grade, and number of positive and negative biopsies. The c index for discrimination between high and low risk of recurrence was 0.68. The probability of progression-free survival ranged from 22% to 97% over the range of risk scores in the study population. Conclusions: This model is based on nationwide population-based data and can be used with a fair predictive accuracy to guide decisions on clinical follow-up after prostatectomy. An online calculator for convenient clinical use of the model is available at www.npcr.se/nomogram
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| 294. |
- Björk, Glenn, et al.
(författare)
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A conserved modified wobble nucleoside (mcm5s2U) in lysyl-tRNA is required for viability in yeast.
- 2007
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Ingår i: RNA. - : Cold Spring Harbor Laboratory. - 1355-8382 .- 1469-9001. ; 13:8, s. 1245-55
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Tidskriftsartikel (refereegranskat)abstract
- Transfer RNAs specific for Gln, Lys, and Glu from all organisms (except Mycoplasma) and organelles have a 2-thiouridine derivative (xm(5)s(2)U) as wobble nucleoside. These tRNAs read the A- and G-ending codons in the split codon boxes His/Gln, Asn/Lys, and Asp/Glu. In eukaryotic cytoplasmic tRNAs the conserved constituent (xm(5)-) in position 5 of uridine is 5-methoxycarbonylmethyl (mcm(5)). A protein (Tuc1p) from yeast resembling the bacterial protein TtcA, which is required for the synthesis of 2-thiocytidine in position 32 of the tRNA, was shown instead to be required for the synthesis of 2-thiouridine in the wobble position (position 34). Apparently, an ancient member of the TtcA family has evolved to thiolate U34 in tRNAs of organisms from the domains Eukarya and Archaea. Deletion of the TUC1 gene together with a deletion of the ELP3 gene, which results in the lack of the mcm(5) side chain, removes all modifications from the wobble uridine derivatives of the cytoplasmic tRNAs specific for Gln, Lys, and Glu, and is lethal to the cell. Since excess of the unmodified form of these three tRNAs rescued the double mutant elp3 tuc1, the primary function of mcm(5)s(2)U34 seems to be to improve the efficiency to read the cognate codons rather than to prevent mis-sense errors. Surprisingly, overexpression of the mcm(5)s(2)U-lacking tRNA(Lys) alone was sufficient to restore viability of the double mutant.
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| 295. |
- Björk, Glenn R, et al.
(författare)
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A primordial tRNA modification required for the evolution of life?
- 2001
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 20:1-2, s. 231-239
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of reading frame maintenance must have been an early event, and presumably preceded the emergence of the three domains Archaea, Bacteria and Eukarya. Features evolved early in reading frame maintenance may still exist in present-day organisms. We show that one such feature may be the modified nucleoside 1-methylguanosine (m(1)G37), which prevents frameshifting and is present adjacent to and 3' of the anticodon (position 37) in the same subset of tRNAs from all organisms, including that with the smallest sequenced genome (Mycoplasma genitalium), and organelles. We have identified the genes encoding the enzyme tRNA(m(1)G37)methyltransferase from all three domains. We also show that they are orthologues, and suggest that they originated from a primordial gene. Lack of m(1)G37 severely impairs the growth of a bacterium and a eukaryote to a similar degree. Yeast tRNA(m(1)G37)methyltransferase also synthesizes 1-methylinosine and participates in the formation of the Y-base (yW). Our results suggest that m(1)G37 existed in tRNA before the divergence of the three domains, and that a tRNA(m(1)G37)methyltrans ferase is part of the minimal set of gene products required for life.
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| 296. |
- Björklund, Anders, et al.
(författare)
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Youth Employment in Sweden
- 1983
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Ingår i: Youth at Work. An International Survey. ; , s. 232-268
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 297. |
- Björklund, Emmelie, et al.
(författare)
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Involvement of Fatty Acid Amide Hydrolase and Fatty Acid Binding Protein 5 in the Uptake of Anandamide by Cell Lines with Different Levels of Fatty Acid Amide Hydrolase Expression: A Pharmacological Study
- 2014
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Ingår i: PLOS ONE. - : PLoS ONE. - 1932-6203. ; 9:7, s. e103479-
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Tidskriftsartikel (refereegranskat)abstract
- Background:The endocannabinoid ligand anandamide (AEA) is removed from the extracellular space by a process ofcellular uptake followed by metabolism. In many cells, such as the RBL-2H3 cell line, inhibition of FAAH activity reduces theobserved uptake, indicating that the enzyme regulates uptake by controlling the intra- : extracellular AEA concentrationgradient. However, in other FAAH-expressing cells, no such effect is seen. It is not clear, however, whether these differencesare methodological in nature or due to properties of the cells themselves. In consequence, we have reinvestigated the roleof FAAH in gating the uptake of AEA.Methodology/Principal Findings: The effects of FAAH inhibition upon AEA uptake were investigated in four cell lines: AT1rat prostate cancer, RBL-2H3 rat basophilic leukaemia, rat C6 glioma and mouse P19 embryonic carcinoma cells. SemiquantitativePCR for the cells and for a rat brain lysate confirmed the expression of FAAH. No obvious expression of atranscript with the expected molecular weight of FLAT was seen. FAAH expression differed between cells, but all four couldaccumulate AEA in a manner inhibitable by the selective FAAH inhibitor URB597. However, there was a difference in thesensitivities seen in the reduction of uptake for a given degree of FAAH inhibition produced by a reversible FAAH inhibitor,with C6 cells being more sensitive than RBL-2H3 cells, despite rather similar expression levels and activities of FAAH. Thefour cell lines all expressed FABP5, and AEA uptake was reduced in the presence of the FABP5 inhibitor SB-FI-26, suggestingthat the different sensitivities to FAAH inhibition for C6 and RBL2H3 cells is not due to differences at the level of FABP-5.Conclusions/Significance: When assayed using the same methodology, different FAAH-expressing cells display differentsensitivities of uptake to FAAH inhibition.
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| 298. |
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| 299. |
- Björklund Svensson, Jonas, et al.
(författare)
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Low-divergence femtosecond X-ray pulses from a passive plasma lens
- 2021
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 17:5, s. 639-645
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Tidskriftsartikel (refereegranskat)abstract
- Electron and X-ray beams originating from compact laser-wakefield accelerators have very small source sizes that are typically on the micrometre scale. Therefore, the beam divergences are relatively high, which makes it difficult to preserve their high quality during transport to applications. To improve on this, tremendous efforts have been invested in controlling the divergence of the electron beams, but no mechanism for generating collimated X-ray beams has yet been demonstrated experimentally. Here we propose and realize a scheme where electron bunches undergoing focusing in a dense, passive plasma lens can emit X-ray pulses with divergences approaching the incoherent limit. Compared with conventional betatron emission, the divergence of this so-called plasma lens radiation is reduced by more than an order of magnitude in solid angle, while maintaining a similar number of emitted photons per electron. This X-ray source offers the possibility of producing brilliant and collimated few-femtosecond X-ray pulses for ultra-fast science, in particular for studies based on X-ray diffraction and absorption spectroscopy. X-ray pulses with low divergences are produced in a laser-wakefield accelerator by focusing electron bunches in a dense passive plasma lens.
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| 300. |
- Björkman, Ann-Sofi, 1983-, et al.
(författare)
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Diagnostic accuracy of dual-energy CT for detection of bone marrow lesions in the subacutely injured knee with MRI as reference method
- 2020
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 61:6, s. 749-759
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Tidskriftsartikel (refereegranskat)abstract
- Dual-energy computer tomography (DECT) can detect post-traumatic bone marrow lesions. Prospective studies of the knee with large numbers of participants and intra-observer agreement assessment are limited. Purpose To investigate the diagnostic accuracy of DECT in detecting bone marrow lesions as well as estimating the bone marrow lesion volume in patients with suspected anterior cruciate ligament trauma with magnetic resonance imaging (MRI) as reference standard. Material and Methods Forty-eight consecutive patients with suspected anterior cruciate ligament injury were imaged bilaterally with DECT within a mean of 25 days (range 4–55 days) following injury and MRI within seven days of DECT. Two readers analyzed DECT virtual non-calcium-blinded images. Consensus MRI was reference standard. Intra- and inter-observer agreement were determined using weighted kappa statistics. Sensitivity, specificity, and negative and positive predictive values were calculated. Bone marrow lesion volumes were measured; for comparison, intra-class correlation coefficient was used. Results The 48 patients (26 men, 22 women; mean age 23 years, age range 15–37 years) were imaged bilaterally yielding 52 knees with bone marrow lesions, of which 44 were in the femur and 41 were in the tibia. Intra- and inter-observer agreement to detect bone marrow lesions was moderate and fair to moderate (κ 0.54–0.66, 95% confidence interval [CI] 0.39–0.80 and 0.37–0.41, 95% CI 0.20–0.57) and overall sensitivity and specificity were 70.1% and 69.1%, respectively. Positive and negative predictive values were 72.9% and 66.1%, respectively. Bone marrow lesion volumes showed excellent intra- and inter-observer agreement (0.83–0.91, 95% CI 0.74–0.94 and 0.76–0.78, 95% CI 0.57–0.87). Conclusion The diagnostic performance of DECT to detect bone marrow lesions in the subacutely injured knee was moderate with intra- and inter-observer agreement ranging from moderate to substantial and fair to moderate. Bone marrow lesion volume correlation was excellent.
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