| 1. |
- Perotti, Daniela, et al.
(författare)
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Hallmark discoveries in the biology of Wilms tumour
- 2023
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Ingår i: Nature Reviews Urology. - 1759-4812.
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Forskningsöversikt (refereegranskat)abstract
- The modern study of Wilms tumour was prompted nearly 50 years ago, when Alfred Knudson proposed the ‘two-hit’ model of tumour development. Since then, the efforts of researchers worldwide have substantially expanded our knowledge of Wilms tumour biology, including major advances in genetics — from cloning the first Wilms tumour gene to high-throughput studies that have revealed the genetic landscape of this tumour. These discoveries improve understanding of the embryonal origin of Wilms tumour, familial occurrences and associated syndromic conditions. Many efforts have been made to find and clinically apply prognostic biomarkers to Wilms tumour, for which outcomes are generally favourable, but treatment of some affected individuals remains challenging. Challenges are also posed by the intratumoural heterogeneity of biomarkers. Furthermore, preclinical models of Wilms tumour, from cell lines to organoid cultures, have evolved. Despite these many achievements, much still remains to be discovered: further molecular understanding of relapse in Wilms tumour and of the multiple origins of bilateral Wilms tumour are two examples of areas under active investigation. International collaboration, especially when large tumour series are required to obtain robust data, will help to answer some of the remaining unresolved questions.
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| 2. |
- Reynolds, Ben C., et al.
(författare)
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An inter-laboratory comparison of Si isotope reference materials
- 2007
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 22:5, s. 561-568
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Tidskriftsartikel (refereegranskat)abstract
- Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (<+/- 0.22 parts per thousand. 1 sigma(SD) delta Si-30) given the different measurement techniques involved. These methods include both acid and alkaline dissolution/fusion, Si separation using cation exchange, selective co-precipitation, and gas-source versus plasma-ionization (high and low resolution) mass-spectrometric techniques. The average delta Si-30 for Diatomite, IRMM-018, and Big-Batch are + 1.26 parts per thousand, -1.65 parts per thousand and -10.48 parts per thousand, respectively, with corresponding delta Si-9 values of + 0.64 parts per thousand, -0.85 parts per thousand and -5.35 parts per thousand for the same standards, respectively. For the most fractionated standard (Big-Batch), results demonstrate a kinetic mass-dependent fractionation effect for atomic Si (i.e., delta Si-29 similar to 0.51 x delta Si-30). There is almost no statistical difference between the mean values obtained by each participating laboratory, with the notable exception of the IRMM-018 standard. This effect could be caused by heterogeneity or contamination of this standard. The results for the other two standards indicate that data sets produced using any of the methods employed in this study will have similar precision and differences are limited to 0.2 parts per thousand in mean delta Si-30 values for a given sample between laboratories, or differences of 0.13 parts per thousand. in mean delta Si-29 values.
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| 3. |
- Reynolds, Ben C., et al.
(författare)
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An inter-laboratory comparison of Si isotope reference materials
- 2007
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Elsevier BV. - 0267-9477 .- 1364-5544. ; 22:5, s. 561-568
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Tidskriftsartikel (refereegranskat)abstract
- Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (<+/- 0.22 parts per thousand. 1 sigma(SD) delta Si-30) given the different measurement techniques involved. These methods include both acid and alkaline dissolution/fusion, Si separation using cation exchange, selective co-precipitation, and gas-source versus plasma-ionization (high and low resolution) mass-spectrometric techniques. The average delta Si-30 for Diatomite, IRMM-018, and Big-Batch are + 1.26 parts per thousand, -1.65 parts per thousand and -10.48 parts per thousand, respectively, with corresponding delta Si-9 values of + 0.64 parts per thousand, -0.85 parts per thousand and -5.35 parts per thousand for the same standards, respectively. For the most fractionated standard (Big-Batch), results demonstrate a kinetic mass-dependent fractionation effect for atomic Si (i.e., delta Si-29 similar to 0.51 x delta Si-30). There is almost no statistical difference between the mean values obtained by each participating laboratory, with the notable exception of the IRMM-018 standard. This effect could be caused by heterogeneity or contamination of this standard. The results for the other two standards indicate that data sets produced using any of the methods employed in this study will have similar precision and differences are limited to 0.2 parts per thousand in mean delta Si-30 values for a given sample between laboratories, or differences of 0.13 parts per thousand. in mean delta Si-29 values.
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| 4. |
- Zitouni, J., et al.
(författare)
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Children with psoriasis and COVID-19 : factors associated with an unfavourable COVID-19 course, and the impact of infection on disease progression (Chi-PsoCov registry)
- 2022
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Ingår i: Journal of the European Academy of Dermatology and Venereology. - : John Wiley & Sons. - 0926-9959 .- 1468-3083. ; 36:11, s. 2076-2086
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Tidskriftsartikel (refereegranskat)abstract
- Background The COVID-19 pandemic has raised questions regarding the management of chronic skin diseases, especially in patients on systemic treatments. Data concerning the use of biologics in adults with psoriasis are reassuring, but data specific to children are missing. Moreover, COVID-19 could impact the course of psoriasis in children. Objectives The aim of this study was therefore to assess the impact of COVID-19 on the psoriasis of children, and the severity of the infection in relation to systemic treatments. Methods We set up an international registry of paediatric psoriasis patients. Children were included if they were under 18 years of age, had a history of psoriasis, or developed it within 1 month of COVID-19 and had COVID-19 with or without symptoms. Results One hundred and twenty episodes of COVID-19 in 117 children (mean age: 12.4 years) were reported. The main clinical form of psoriasis was plaque type (69.4%). Most children were without systemic treatment (54.2%); 33 (28.3%) were on biologic therapies, and 24 (20%) on non-biologic systemic drugs. COVID-19 was confirmed in 106 children (88.3%) and 3 children had two COVID-19 infections each. COVID-19 was symptomatic for 75 children (62.5%) with a mean duration of 6.5 days, significantly longer for children on non-biologic systemic treatments (P = 0.02) and without systemic treatment (P = 0.006) when compared with children on biologics. The six children who required hospitalization were more frequently under non-biologic systemic treatment when compared with the other children (P = 0.01), and particularly under methotrexate (P = 0.03). After COVID-19, the psoriasis worsened in 17 cases (15.2%). Nine children (8%) developed a psoriasis in the month following COVID-19, mainly a guttate form (P = 0.01). Discussion Biologics appear to be safe with no increased risk of severe form of COVID-19 in children with psoriasis. COVID-19 was responsible for the development of psoriasis or the worsening of a known psoriasis for some children.
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| 5. |
- Lee, Hyun Ju, et al.
(författare)
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Intricate role of water in proton transport through cytochrome c oxidase
- 2010
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 132:45, s. 16225-16239
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Tidskriftsartikel (refereegranskat)abstract
- Cytochrome c oxidase (CytcO), the final electron acceptor in the respiratory chain, catalyzes the reduction of O2 to H2O while simultaneously pumping protons across the inner mitochondrial or bacterial membrane to maintain a transmembrane electrochemical gradient that drives, for example, ATP synthesis. In this work mutations that were predicted to alter proton translocation and enzyme activity in preliminary computational studies are characterized with extensive experimental and computational analysis. The mutations were introduced in the D pathway, one of two proton-uptake pathways, in CytcO from Rhodobacter sphaeroides. Serine residues 200 and 201, which are hydrogen-bonded to crystallographically resolved water molecules halfway up the D pathway, were replaced by more bulky hydrophobic residues (Ser200Ile, Ser200Val/Ser201Val, and Ser200Val/Ser201Tyr) to query the effects of changing the local structure on enzyme activity as well as proton uptake, release, and intermediate transitions. In addition, the effects of these mutations on internal proton transfer were investigated by blocking proton uptake at the pathway entrance (Asp132Asn replacement in addition to the above-mentioned mutations). Even though the overall activities of all mutant CytcO's were lowered, both the Ser200Ile and Ser200Val/Ser201Val variants maintained the ability to pump protons. The lowered activities were shown to be due to slowed oxidation kinetics during the PR → F and F → O transitions (PR is the "peroxy" intermediate formed at the catalytic site upon reaction of the four-electron-reduced CytcO with O2, F is the oxoferryl intermediate, and O is the fully oxidized CytcO). Furthermore, the PR → F transition is shown to be essentially pH independent up to pH 12 (i.e., the apparent pKa of Glu286 is increased from 9.4 by at least 3 pKa units) in the Ser200Val/Ser201Val mutant. Explicit simulations of proton transport in the mutated enzymes revealed that the solvation dynamics can cause intriguing energetic consequences and hence provide mechanistic insights that would never be detected in static structures or simulations of the system with fixed protonation states (i.e., lacking explicit proton transport). The results are discussed in terms of the proton-pumping mechanism of CytcO.
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| 6. |
- Browkin, J., et al.
(författare)
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On Sequences of Squares with Constant Second Differences
- 2006
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Ingår i: Canadian Mathematical Bulletin. ; 49:4, s. 481-491
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to study sequences of integers for which the second differences between their squares are constant. We show that there are infinitely many nontrivial monotone sextuples having this property and discuss some related problems.
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| 7. |
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| 8. |
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| 9. |
- Browkin, J., et al.
(författare)
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Separable free quadratic algebras over quadratic integers
- 2004
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Ingår i: Journal of Number Theory. - : Elsevier BV. - 0022-314X .- 1096-1658. ; 109:2, s. 379-389
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the paper is to determine all free separable quadratic algebras over the rings of integers of quadratic fields in terms of the properties of the fundamental unit in the real case. The paper corrects some earlier published results on the subject. © 2004 Elsevier Inc. All rights reserved.
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| 10. |
- Brzezinski, J., et al.
(författare)
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On the congruence ax plus by 1 modulo xy
- 2005
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Ingår i: Experimental Mathematics. - : Informa UK Limited. - 1058-6458 .- 1944-950X. ; 14:4, s. 391-401
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Tidskriftsartikel (refereegranskat)abstract
- We give bounds on the number of solutions to the Diophantine equation (X + 1/x)(Y + 1/y) = n as n tends to infinity. These bounds are related to the number of solutions to congruences of the form ax + by equivalent to 1 modulo xy.
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| 11. |
- Collins, Ruairi, et al.
(författare)
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Biochemical discrimination between selenium and sulfur 1 : a single residue provides selenium specificity to human selenocysteine lyase
- 2012
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Ingår i: PLoS One. - Stockholm : Karolinska Institutet, Dept of Medical Biochemistry and Biophysics. - 1932-6203.
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Tidskriftsartikel (refereegranskat)abstract
- Selenium and sulfur are two closely related basic elements utilized in nature for a vast array of biochemical reactions. While toxic at higher concentrations, selenium is an essential trace element incorporated into selenoproteins as selenocysteine (Sec), the selenium analogue of cysteine (Cys). Sec lyases (SCLs) and Cys desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys and generally act on both substrates. In contrast, human SCL (hSCL) is specific for Sec although the only difference between Sec and Cys is the identity of a single atom. The chemical basis of this selenium-over-sulfur discrimination is not understood. Here we describe the X-ray crystal structure of hSCL and identify Asp146 as the key residue that provides the Sec specificity. A D146K variant resulted in loss of Sec specificity and appearance of CD activity. A dynamic active site segment also provides the structural prerequisites for direct product delivery of selenide produced by Sec cleavage, thus avoiding release of reactive selenide species into the cell. We thus here define a molecular determinant for enzymatic specificity discrimination between a single selenium versus sulfur atom, elements with very similar chemical properties. Our findings thus provide molecular insights into a key level of control in human selenium and selenoprotein turnover and metabolism.
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| 12. |
- Johansson, Ann-Louise, et al.
(författare)
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Biochemical discrimination between selenium and sulfur 2 : mechanistic investigation of the selenium specificity of human selenocysteine lyase
- 2012
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Ingår i: PLoS One. - Stockholm : Karolinska Institutet, Dept of Medical Biochemistry and Biophysics. - 1932-6203.
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Tidskriftsartikel (refereegranskat)abstract
- Selenium is an essential trace element incorporated into selenoproteins as selenocysteine. Selenocysteine (Sec) lyases (SCLs) and cysteine (Cys) desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys, respectively, and generally accept both substrates. Intriguingly, human SCL (hSCL) is specific for Sec even though the only difference between Sec and Cys is a single chalcogen atom. The crystal structure of hSCL was recently determined and gain-of-function protein variants that also could accept Cys as substrate were identified. To obtain mechanistic insight into the chemical basis for its substrate discrimination, we here report time-resolved spectroscopic studies comparing the reactions of the Sec-specific wild-type hSCL and the gain-of-function D146K/H389T variant, when given Cys as a substrate. The data are interpreted in light of other studies of SCL/CD enzymes and offer mechanistic insight into the function of the wild-type enzyme. Based on these results and previously available data we propose a reaction mechanism whereby the Sec over Cys specificity is achieved using a combination of chemical and physico-mechanical control mechanisms.
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| 13. |
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| 14. |
- Moe, Agnes, et al.
(författare)
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The respiratory supercomplex from C. glutamicum
- 2022
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 30:3, s. 338-349
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Tidskriftsartikel (refereegranskat)abstract
- Corynebacterium glutamicum is a preferentially aerobic gram-positive bacterium belonging to the phylum Actinobacteria, which also includes the pathogen Mycobacterium tuberculosis. In these bacteria, respiratory complexes III and IV form a CIII2CIV2 supercomplex that catalyzes oxidation of menaquinol and reduction of dioxygen to water. We isolated the C. glutamicum supercomplex and used cryo-EM to determine its structure at 2.9 Å resolution. The structure shows a central CIII2 dimer flanked by a CIV on two sides. A menaquinone is bound in each of the QN and QP sites in each CIII and an additional menaquinone is positioned ∼14 Å from heme bL. A di-heme cyt. cc subunit electronically connects each CIII with an adjacent CIV, with the Rieske iron-sulfur protein positioned with the iron near heme bL. Multiple subunits interact to form a convoluted sub-structure at the cytoplasmic side of the supercomplex, which defines a path for proton transfer into CIV.
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| 15. |
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| 17. |
- Yanofsky, David J., et al.
(författare)
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Structure of mycobacterial CIII2CIV2 respiratory supercomplex bound to the tuberculosis drug candidate telacebec (Q203)
- 2021
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Ingår i: eLIFE. - 2050-084X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The imidazopyridine telacebec, also known as Q203, is one of only a few new classes of compounds in more than 50 years with demonstrated antituberculosis activity in humans. Telacebec inhibits the mycobacterial respiratory supercomplex composed of complexes III and IV (CIII2CIV2). In mycobacterial electron transport chains, CIII2CIV2 replaces canonical CIII and CIV, transferring electrons from the intermediate carrier menaquinol to the final acceptor, molecular oxygen, while simultaneously transferring protons across the inner membrane to power ATP synthesis. We show that telacebec inhibits the menaquinol:oxygen oxidoreductase activity of purified Mycobacterium smegmatis CIII2CIV2 at concentrations similar to those needed to inhibit electron transfer in mycobacterial membranes and Mycobacterium tuberculosis growth in culture. We then used electron cryomicroscopy (cryoEM) to determine structures of CIII2CIV2 both in the presence and absence of telacebec. The structures suggest that telacebec prevents menaquinol oxidation by blocking two different menaquinol binding modes to prevent CIII2CIV2 activity.
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