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| 2. |
- Andrén, Margareta, et al.
(författare)
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Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland
- 2016
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Ingår i: Journal of Geophysical Research - Solid Earth. - 2169-9313 .- 2169-9356. ; 121:4, s. 2315-2337
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Tidskriftsartikel (refereegranskat)abstract
- Chemical analysis of groundwater samples collected from a borehole at Hafralækur, northernIceland, from October 2008 to June 2015 revealed (1) a long-term decrease in concentration of Si and Naand (2) an abrupt increase in concentration of Na before each of two consecutive M > 5 earthquakes whichoccurred in 2012 and 2013, both 76 km from Hafralækur. Based on a geochemical (major elements and stableisotopes), petrological, and mineralogical study of drill cuttings taken from an adjacent borehole, we areable to show that (1) the long-term decrease in concentration of Si and Na was caused by constant volumereplacement of labradorite by analcime coupled with precipitation of zeolites in vesicles and along fracturesand (2) the abrupt increase of Na concentration before the first earthquake records a switchover tononstoichiometric dissolution of analcime with preferential release of Na into groundwater. We attributedecay of the Na peaks, which followed and coincided with each earthquake to uptake of Na along fracturedor porous boundaries between labradorite and analcime crystals. Possible causes of these Na peaks are anincrease of reactive surface area caused by fracturing or a shift from chemical equilibrium caused by mixingbetween groundwater components. Both could have been triggered by preseismic dilation, which was alsoinferred in a previous study by Skelton et al. (2014). The mechanism behind preseismic dilation so far from thefocus of an earthquake remains unknown.
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| 4. |
- Diderholm, Erik, et al.
(författare)
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The prognostic and therapeutic implications of increased troponin T levels and ST depression in unstable coronary artery disease : the FRISC II invasive troponin T electrocardiogram substudy
- 2002
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Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 143:5, s. 760-767
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In unstable coronary artery disease, both increased troponin T level and occurrence of ST-segment depression are associated with a worse prognosis. In the Fast Revascularisation in InStability in Coronary disease trial II invasive study, we evaluated whether the troponin T level, alone and combined with ST depression, identified more severe coronary artery disease or a greater efficacy of an early invasive strategy. METHODS: In the study, 2457 patients with unstable coronary artery disease were randomized to early invasive or noninvasive strategy. Troponin T value and admission electrocardiogram results were available in 2286 patients. RESULTS: In the noninvasive cohort, death or myocardial infarction occurred in 16.6% with troponin T level > or =0.03 microg/L versus 8.5% with troponin T level < 0.03 microg/L (P <.001). In the invasive group, 49% of patients with both ST depression and troponin T level > or =0.03 microg/L had 3-vessel or left main disease compared with 17% if neither finding was present (P <.001). The invasive strategy reduced death/myocardial infarction at 12 months in the cohort with both ST depression and troponin T level > or =0.03 microg/L from 22.1% to 13.2% (risk ratio, 0.60; 95% confidence interval, 0.43 to 0.82; P =.001). In the cohort with either ST depression or troponin T level > or =0.03 microg/L or neither of these findings, the absolute gain of the invasive strategy was smaller and more uncertain. CONCLUSION: Patients with unstable coronary artery disease with the combination of troponin T level > or =0.03 microg/L and ST depression have a poor prognosis and, in half of the cases, 3-vessel or left main disease. In these patients, an early invasive strategy will substantially reduce death/myocardial infarction.
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| 5. |
- Elmståhl, Sölve, et al.
(författare)
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Malnutrition in geriatric patients : A neglected problem?
- 1997
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Ingår i: Journal of Advanced Nursing. - : Wiley. - 0309-2402 .- 1365-2648. ; 26:5, s. 851-855
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Tidskriftsartikel (refereegranskat)abstract
- The nutrient intake in geriatric long-stay patients and the mortality risk associated with low energy intake were studied in 61 patients, 43 women and 18 men, with a mean age of 87 years, at a geriatric long-stay care hospital during a 6-month follow-up. Dietary intake was assessed with a 9-day dietary record. Energy expenditure was calculated assuming a physical activity level of 1.33 × basal metabolic rate (BMR), predicted from equations given by FAO/WHO. Mean energy intakes were 1557 kcal in men and 1280 kcal in women; 84% of the patients had an intake below estimated energy expenditure and 30% were below estimated BMR. Only 5% received dietary supplement. Eleven out of the 61 patients died during the follow-up and the deceased had lower energy intake than the others (1185 kcal vs 1401 kcal, P<0.05). An energy intake below median (1378 kcal) was associated with an age adjusted increased 6-month mortality risk, odds ratio 12.5. A high proportion of geriatric long-stay patients report dietary intake far below present recommendations and are thereby at risk for having/developing malnutrition. Improved surveillance of geriatric long-stay patients' dietary habits seems justified.
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| 6. |
- Genberg, Margareta, et al.
(författare)
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Cardiac Function After Hematopoietic Cell Transplantation : An Echocardiographic Cross-Sectional Study in Young Adults Treated in Childhood
- 2015
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Ingår i: Pediatric Blood & Cancer. - : Wiley. - 1545-5009 .- 1545-5017. ; 62:1, s. 143-147
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundHematopoietic cell transplantation (HCT) including preparative regimens with chemotherapy and total body irradiation (TBI) is an accepted treatment for many malignant disorders but may have side-effects for several organs, including the cardiovascular system. The aim of this study was to study very long-term consequences on cardiac function after childhood HCT. ProcedureCardiac function was evaluated using echocardiography and levels of NT-proBNP and growth hormone (GHmax) in 18 patients, at a median of 18 years after HCT including TBI, and in 18 matched controls. ResultsPatients after HCT had cardiac dimensions, volumes, and left ventricular ejection fractions within normal range after correction for body size. However, compared with the control group, patients after HCT had significantly lower E/A ratio, as a measure of left ventricular diastolic function, significantly lower fractional shortening and mitral annular plane systolic excursion, as measures of left ventricular systolic function, significantly lower tricuspid annular plane systolic excursion, as a measure of right ventricular function, and significantly higher NT-proBNP, as a measure of total cardiac function. Also, pulmonary flow acceleration time was shorter in the group after HCT, indicating possible pulmonary involvement. Heart rate was significantly higher and GHmax significantly lower in patients after HCT. ConclusionsAlmost two decades after HCT, including preparative regimens with TBI, cardiac function in patients was found to be within normal range. However, when compared with a healthy control group, patients after HCT showed lower systolic and diastolic left ventricular function as well as lower right ventricular function. Pediatr Blood Cancer 2015;62:143-147.
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| 7. |
- Genberg, Margareta, et al.
(författare)
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Commonly used reference values underestimate oxygen uptake in healthy, 50-year-old Swedish women.
- 2018
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 38:1, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- Cardiopulmonary exercise testing (CPET) is the gold standard among clinical exercise tests. It combines a conventional stress test with measurement of oxygen uptake (VO2 ) and CO2 production. No validated Swedish reference values exist, and reference values in women are generally understudied. Moreover, the importance of achieved respiratory exchange ratio (RER) and the significance of breathing reserve (BR) at peak exercise in healthy individuals are poorly understood. We compared VO2 at maximal load (peakVO2 ) and anaerobic threshold (VO2@AT ) in healthy Swedish individuals with commonly used reference values, taking gender into account. Further, we analysed maximal workload and peakVO2 with regard to peak RER and BR. In all, 181 healthy, 50-year-old individuals (91 women) performed CPET. PeakVO2 was best predicted using Jones et al. (100·5%), while SHIP reference values underestimated peakVO2 most: 112·5%. Furthermore, underestimation of peakVO2 in women was found for all studied reference values (P<0·001) and was largest for SHIP: women had 128% of predicted peakVO2 , while men had 104%. PeakVO2 was similar in subjects with peak RER of 1-1·1 and RER > 1·1 (2 328·7 versus 2 176·7 ml min(-1) , P = 0·11). Lower BR (≤30%) related to significantly higher peakVO2 (P<0·001). In conclusion, peakVO2 was best predicted by Jones. All studied reference values underestimated oxygen uptake in women. No evidence for demanding RER > 1·1 in healthy individuals was found. A lowered BR is probably a normal response to higher workloads in healthy individuals.
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| 8. |
- Luptáková, Dominika, et al.
(författare)
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Neuropharmacokinetic visualization of regional and subregional unbound antipsychotic drug transport across the blood-brain barrier.
- 2021
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Ingår i: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 26, s. 7732-7745
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive determination of the extent of drug transport across the region-specific blood-brain barrier (BBB) is a major challenge in preclinical studies. Multiple approaches are needed to determine the regional free (unbound) drug concentration at which a drug engages with its therapeutic target. We present an approach that merges in vivo and in vitro neuropharmacokinetic investigations with mass spectrometry imaging to quantify and visualize both the extent of unbound drug BBB transport and the post-BBB cerebral distribution of drugs at regional and subregional levels. Direct imaging of the antipsychotic drugs risperidone, clozapine, and olanzapine using this approach enabled differentiation of regional and subregional BBB transport characteristics at 20-µm resolution in small brain regions, which could not be achieved by other means. Our approach allows investigation of heterogeneity in BBB transport and presents new possibilities for molecular psychiatrists by facilitating interpretation of regional target-site exposure results and decision-making.
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| 9. |
- Skelton, Alasdair, et al.
(författare)
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Changes in groundwater chemistry before two consecutive earthquakes in Iceland
- 2014
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 7:10, s. 752-756
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater chemistry has been observed to change before earthquakes and is proposed as a precursor signal. Such changes include variations in radon count rates(1,2), concentrations of dissolved elements(3-5) and stable isotope ratios(4,5). Changes in seismicwave velocities(6), water levels in boreholes(7), micro-seismicity(8) and shear wave splitting(9) are also thought to precede earthquakes. Precursor activity has been attributed to expansion of rock volume(7,10,11). However, most studies of precursory phenomena lack sufficient data to rule out other explanations unrelated to earthquakes(12). For example, reproducibility of a precursor signal has seldom been shown and few precursors have been evaluated statistically. Here we analyse the stable isotope ratios and dissolved element concentrations of groundwater taken from a borehole in northern Iceland between 2008 and 2013. We find that the chemistry of the groundwater changed four to six months before two greater than magnitude 5 earthquakes that occurred in October 2012 and April 2013. Statistical analyses indicate that the changes in groundwater chemistry were associated with the earthquakes. We suggest that the changes were caused by crustal dilation associated with stress build-up before each earthquake, which caused different groundwater components to mix. Although the changes we detect are specific for the site in Iceland, we infer that similar processes may be active elsewhere, and that groundwater chemistry is a promising target for future studies on the predictability of earthquakes.
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| 10. |
- Skelton, Alasdair, et al.
(författare)
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Hydrochemical Changes Before and After Earthquakes Based on Long-Term Measurements of Multiple Parameters at Two Sites in Northern IcelandA Review
- 2019
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Ingår i: Journal of Geophysical Research - Solid Earth. - 2169-9313 .- 2169-9356. ; 124:3, s. 2702-2720
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Forskningsöversikt (refereegranskat)abstract
- Hydrochemical changes before and after earthquakes have been reported for over 50years. However, few reports provide sufficient data for an association to be verified statistically. Also, no mechanism has been proposed to explain why hydrochemical changes are observed far from earthquake foci where associated strains are small (<10(-8)). Here we address these challenges based on time series of multiple hydrochemical parameters from two sites in northern Iceland. We report hydrochemical changes before and after M >5 earthquakes in 2002, 2012, and 2013. The longevity of the time series (10 and 16years) permits statistical verification of coupling between hydrochemical changes and earthquakes. We used a Student t test to find significant hydrochemical changes and a binomial test to confirm association with earthquakes. Probable association was confirmed for preseismic changes based on five parameters (Na, Si, K, O-18, and H-2) and postseismic changes based on eight parameters (Ca, Na, Si, Cl, F, SO4, O-18, and H-2). Using concentration ratios and stable isotope values, we showed that (1) gradual preseismic changes were caused by source mixing, which resulted in a shift from equilibrium and triggered water-rock interaction; (2) postseismic changes were caused by rapid source mixing; and (3) longer-term hydrochemical changes were caused by source mixing and mineral growth. Because hydrochemical changes occur at small earthquake-related strains, we attribute source mixing and water-rock interaction to microscale fracturing. Because fracture density and size scale inversely, we infer that mixing of nearby sources and water-rock interaction are feasible responses to small earthquake-related strains. Plain Language Summary Changes in groundwater chemistry before and after earthquakes have been reported for over 50years. However, few studies have been able to prove that the earthquakes caused these changes. Also, no study has explained why these changes are often reported far from where the earthquake occurred. Here we address these challenges based on measurements of groundwater chemistry made at two sites in northern Iceland over time periods of 10 and 16years. We used statistical methods to prove that the earthquakes caused changes of ground water chemistry both before and after the earthquakes. We showed that changes of groundwater chemistry before earthquakes were caused by slow mixing between different groundwaters, which triggered reactions with the wall rock that changed groundwater chemistry, and that changes of groundwater chemistry after earthquakes were causes by rapid mixing between different groundwaters. That these changes were detected far from where the earthquakes occurred suggests that cracking of the wall rock at a very small scale was all that was needed for mixing of different groundwaters and reactions with the wall rock to occur.
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