| 1. |
- Staniec, Dominika, et al.
(författare)
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Calcium Regulates the Activity and Structural Stability of Tpr, a Bacterial Calpain-like Peptidase.
- 2015
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 290:45, s. 27248-27260
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Tidskriftsartikel (refereegranskat)abstract
- Porphyromonas gingivalis is a peptide-fermenting asaccharolytic periodontal pathogen. Its genome contains several genes encoding cysteine peptidases other than gingipains. One of these genes (PG1055) encodes a protein called Tpr (thiol protease), which has sequence similarity to cysteine peptidases of the papain and calpain families. In this study, we biochemically characterize Tpr. We found that the 55 kDa Tpr inactive zymogen proteolytically processes itself into active forms of 48 kDa, 37 kDa, and 33 kDa via sequential truncations at the N-terminus. These processed molecular forms of Tpr are associated with the bacterial outer membrane, where they are likely responsible for the generation of metabolic peptides required for survival of the pathogen. Both autoprocessing and activity were dependent on calcium concentrations greater than 1 mM, consistent with the protein's activity within the intestinal and inflammatory milieus. Calcium also stabilized the Tpr structure and rendered the protein fully resistant to proteolytic degradation by gingipains. Together, our findings suggest that Tpr is an example of a bacterial calpain, a calcium-responsive peptidase that may generate substrates required for the peptide-fermenting metabolism of P. gingivalis. Aside from nutrient generation, Tpr may also be involved in evasion of host immune response through degradation of the antimicrobial peptide LL-37 and complement proteins C3, C4 and C5. Taken together, these results indicate that Tpr likely represents an important pathogenesis factor for P. gingivalis.
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| 2. |
- Amini, Kasra, et al.
(författare)
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Alignment, orientation, and Coulomb explosion of difluoroiodobenzene studied with the pixel imaging mass spectrometry (PImMS) camera
- 2017
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 147:1
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced adiabatic alignment and mixed-field orientation of 2,6-difluoroiodobenzene (C6H3F2I) molecules are probed by Coulomb explosion imaging following either near-infrared strong-field ionization or extreme-ultraviolet multi-photon inner-shell ionization using free-electron laser pulses. The resulting photoelectrons and fragment ions are captured by a double-sided velocity map imaging spectrometer and projected onto two position-sensitive detectors. The ion side of the spectrometer is equipped with a pixel imaging mass spectrometry camera, a time-stamping pixelated detector that can record the hit positions and arrival times of up to four ions per pixel per acquisition cycle. Thus, the time-of-flight trace and ion momentum distributions for all fragments can be recorded simultaneously. We show that we can obtain a high degree of one-and three-dimensional alignment and mixed-field orientation and compare the Coulomb explosion process induced at both wavelengths.
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| 3. |
- Amini, Kasra, et al.
(författare)
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Photodissociation of aligned CH3I and C6H3F2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization
- 2018
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon-iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.
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| 4. |
- Hultdin, Johan, et al.
(författare)
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Elevated plasma homocysteine : cause or consequence of myocardial infarction?
- 2004
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 256:6, s. 491-498
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To determine whether a first myocardial infarction leads to increased plasma homocysteine concentrations and whether the association between homocysteine and myocardial infarction was greater at follow-up compared with baseline. DESIGN: A population-based, prospective, nested case-referent study. SETTING: Screening took place at the nearest health survey centre in northern Sweden. SUBJECTS: Of more than 36,000 persons screened, 78 developed a first myocardial infarction (average 18 months after sampling). Fifty of these had participated in a follow-up health survey (average 8(1/2) years between surveys) and were sex- and age-matched with 56 referents. MAIN OUTCOME MEASURES: Comparison of plasma homocysteine levels in case and referent subjects before and after development of a first myocardial infarction. RESULTS: No statistically significant difference was found between cases and referents regarding homocysteine at baseline or follow-up. Plasma homocysteine and plasma creatinine increased significantly, and plasma albumin decreased significantly over time. Conditional univariate logistic regression indicated that high homocysteine at follow-up but not baseline was associated with first myocardial infarction (OR 2.49; 95% CI: 1.03-6.02), but the relation disappeared in multivariate analyses including plasma creatinine and plasma albumin. High plasma creatinine remained associated with first myocardial infarction at both baseline (OR 2.94; 95% CI: 1.05-8.21) and follow-up (OR 3.38; 95% CI: 1.21-9.48). CONCLUSION: In this study, first myocardial infarction did not cause increased plasma homocysteine concentration.
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| 6. |
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| 7. |
- Savelyev, Evgeny, et al.
(författare)
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Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser
- 2017
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene (C6H3F2I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. We discuss in detail the necessary data analysis steps and describe the origin of the time-dependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment.
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| 8. |
- Thøgersen, Anna M., et al.
(författare)
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Changes in plasma C-reactive protein and hemostatic factors prior to and after a first myocardial infarction with a median follow-up time of 8 years
- 2009
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Ingår i: Blood Coagulation and Fibrinolysis. - 0957-5235 .- 1473-5733. ; 20:5, s. 340-346
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to determine whether a first myocardial infarction leads to increased plasma levels of hemostatic factors and high sensitive C-reactive protein (hs-CRP) and whether the association between theses biomarkers and myocardial infarction was greater at follow-up compared with baseline. Of more than 36,000 persons screened in northern Sweden, 78 developed a first myocardial infarction (on average 18 months after sampling) in a population-based, prospective, nested patient-referent study. Fifty of these had participated in a follow-up health survey (on average 8 and a half years between surveys) and were sex-matched and age-matched with 56 referents. The mean increases in hs-CRP, tissue plasminogen activator (tPA) mass, plasminogen activator inhibitor-1 mass, and tPA/plasminogen activator inhibitor-1 complex concentration and von Willebrand factor among patients and referents were comparable during follow-up. Conditional logistic regression indicated that hs-CRP was not significantly associated with first myocardial infarction in a univariate analysis, whereas high plasma levels of tPA and creatinine were significantly associated with outcome at baseline and follow-up. tPA/plasminogen activator inhibitor-1 complex was not superior to tPA as a risk marker in this study. A first myocardial infarction did not in this study induce significantly different changes in plasma levels of hs-CRP and hemostatic factors among patients compared with referents during follow-up.
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