| 11. |
- Cinthio, Magnus, et al.
(författare)
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Evaluation of an algorithm for arterial lumen diameter measurements by means of ultrasound.
- 2010
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Ingår i: Medical & Biological Engineering & Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 48, s. 1133-1140
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Tidskriftsartikel (refereegranskat)abstract
- We have developed an algorithm for arterial luminal diameter measurement by means of ultrasound and evaluated the algorithm on agar vessel phantoms and in vivo. The algorithm utilises relative threshold detection on the inner slopes of the arterial walls before the resolution is improved by solving the equation of a straight line between the samples around the threshold value. Further, correction distances added to compensate for the underestimation when using the inner slopes were found to be 304 mum for the near wall and 415 mum for the far wall. The measured mean diameters of ten consecutive images of 3-, 6- and 9-mm phantoms were 3,006 mum (SD 4), 5,918 mum (SD 1) and 8,936 mum (SD 2), respectively. The mean differences between the images were 0.19, 0.04 and 0.37 mum, respectively. In vivo, the intra- and inter-observer variabilities were -64 mum (2SD 358) and -57 mum (2SD 366), respectively.
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| 12. |
- Erlöv, Tobias, et al.
(författare)
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A method for measuring the variation of intima-media thickness during the entire cardiac cycle using B-Mode images
- 2011
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Ingår i: 2011 IEEE International Ultrasonics Symposium (IUS). - 9781457712531 ; , s. 2126-2129
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Konferensbidrag (refereegranskat)abstract
- Increased intima-media thickness (IMT) has been shown to predict cardiovascular risk, and measurement of intima-media thickness has been extensively used in medical research since the mid-1990s. IMT is conventionally measured by manual tracing, however this method is very time-consuming and suffers from large inter-observer variability. Numerous methods, both semi-automatic and fully-automatic, have been suggested to limit the influence of the observer. However, most methods only report one value per cardiac cycle instead of the variation of IMT over time. We propose a new method that measures the variation of IMT during the entire cardiac cycle. The method tracks spatial variations with compensation for both longitudinal movement and angle variations. This enables detection of positions where an inaccurate measurement of IMT has occurred. These can then be removed from the calculations in order to maximize the accuracy. The method was evaluated in vivo on 20 healthy individuals (mean age 38 years, range 25-57). The overall IMT in diastole (IMTdia) was 717+/-69 mu m and the intima-media compression (IMC) was 66+/-21 mu m which corresponds to a 9.2+/-2.6% maximal compression of the arterial wall during a cardiac cycle. The CV was 3.5% for IMTdia and 9.9% for IMC. Extending traditional IMT measurement to include also the variation of IMT during a cardiac cycle may improve the individual risk classification for cardiovascular diseases.
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| 13. |
- Erlöv, Tobias, et al.
(författare)
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A Method to Measure Shear Strain with High Spatial Resolution in the Arterial Wall Non-Invasively in vivo by Tracking Zero-Crossings of B-Mode Intensity Gradients
- 2010
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Ingår i: Proceedings - IEEE Ultrasonics Symposium. - 9781457703812 ; , s. 491-494
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Konferensbidrag (refereegranskat)abstract
- We have previously shown that there is a distinct longitudinal movement of the arterial wall during a cardiac cycle. This movement is larger in the intima-media region than in the adventitial region which introduces a substantial shear strain within the arterial wall. Our previously developed echo-tracking algorithm measured this shear strain by tracking two separate echoes, one in the intima-media region and one in the adventitia region and thus only a linear distribution was evaluated. The objective of this study was to suggest and evaluate a new improved method which can measure the intramural shear strain with higher spatial resolution and thereby provide more information on this new and rather unknown phenomenon. The mean maximum shear strain was 0.82 radians with a standard deviation of 0.17 radians and a CV-value of 14.2%. The total mean difference in measured longitudinal movement between the new and previous method was 10μm with a standard deviation of 90μm and a CV-value of 12.8%. The spatial distribution of the intramural shear strain seems to be very non-linear with a large amount of shear strain occurring in a small section around the transition between the media and adventitia layers.
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| 14. |
- Folke, Carl, et al.
(författare)
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Reconnecting to the biosphere
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:7, s. 719-738
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Tidskriftsartikel (refereegranskat)abstract
- Humanity has emerged as a major force in the operation of the biosphere, with a significant imprint on the Earth System, challenging social-ecological resilience. This new situation calls for a fundamental shift in perspectives, world views, and institutions. Human development and progress must be reconnected to the capacity of the biosphere and essential ecosystem services to be sustained. Governance challenges include a highly interconnected and faster world, cascading social-ecological interactions and planetary boundaries that create vulnerabilities but also opportunities for social-ecological change and transformation. Tipping points and thresholds highlight the importance of understanding and managing resilience. New modes of flexible governance are emerging. A central challenge is to reconnect these efforts to the changing preconditions for societal development as active stewards of the Earth System. We suggest that the Millennium Development Goals need to be reframed in such a planetary stewardship context combined with a call for a new social contract on global sustainability. The ongoing mind shift in human relations with Earth and its boundaries provides exciting opportunities for societal development in collaboration with the biosphere-a global sustainability agenda for humanity.
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| 15. |
- Granlund, Moa Z., 1983-, et al.
(författare)
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Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel
- 2014
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 154, s. 386-394
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.
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| 16. |
- Grüner, Daniel, et al.
(författare)
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Argon Ion Beam Polishing : A Preparation Technique for Evaluating the Interface of Osseointegrated Implants with High Resolution
- 2011
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Ingår i: International Journal of Oral & Maxillofacial Implants. - 0882-2786 .- 1942-4434. ; 26:3, s. 547-552
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The objective of this study was to assess the use of ion beam polishing for preparing cross sections suitable for high-resolution scanning electron microscope (SEM) investigation of dental implants with a brittle porous oxide layer and of bone/implant interfaces. Materials and Methods: Thirteen Nobel Biocare TiUnite implants were placed in minipigs. After 4 weeks, the implant and surrounding bone were removed en bloc and the implant was cut axially into two halves. The cross section was then polished with an argon ion beam. Additionally, ion beam-polished cross sections were prepared from four as-received implants. Ion beam-polished surfaces were studied with a field emission SEM (FE-SEM). Results: With FE-SEM, up to 1 mm along the interface of ion beam-polished implant surfaces can be studied with a resolution of a few nanometers. Filled and unfilled pores of the porous TiUnite coating can be distinguished, providing information on pore accessibility. Implant-bone interfaces can be analyzed using backscattered electron images, where titanium, the oxide layer, mineralized extracellular matrix, and osteocyte lacunae/resin/soft tissue can easily be distinguished as a result of atomic number contrast and the sharp boundaries between the different materials. Filled and unfilled pores can be distinguished. Characterization of local chemistry is possible with energy dispersive X-ray spectrometry, and bone growth into small pores (< 1 mu m) can be unambiguously confirmed. Conclusion: FE-SEM complements the established methods for the characterization of interfaces and bridges the wide gap in accessible length scale and resolution between the observations of mechanically polished interfaces by optical or scanning electron microscopes and the observation of focused ion beam-milled sections in a transmission electron microscope.
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| 17. |
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| 18. |
- Gullestad, Lars, et al.
(författare)
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Everolimus With Reduced Calcineurin Inhibitor in Thoracic Transplant Recipients With Renal Dysfunction: A Multicenter, Randomized Trial
- 2010
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Ingår i: Transplantation. - : Williams and Wilkins. - 0041-1337 .- 1534-6080. ; 89:7, s. 864-872
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Tidskriftsartikel (refereegranskat)abstract
- Background. The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking. Methods. In a 12-month, open-labeled, multicenter study, maintenance thoracic transplant patients (glomerular filtration rate greater than= 20 mL/min/1.73m(2) and less than90 mL/min/1.73 m(2)) greater than1 year posttransplant were randomized to continue their current CNI-based immunosuppression or start everolimus with predefined CNI exposure reduction. Results. Two hundred eighty-two patients were randomized (140 everolimus, 142 controls; 190 heart, 92 lung transplants). From baseline to month 12, mean cyclosporine and tacrolimus trough levels in the everolimus cohort decreased by 57% and 56%, respectively. The primary endpoint, mean change in measured glomerular filtration rate from baseline to month 12, was 4.6 mL/min with everolimus and -0.5 mL/min in controls (Pless than0.0001). Everolimus-treated heart and lung transplant patients in the lowest tertile for time posttransplant exhibited mean increases of 7.8 mL/min and 4.9 mL/min, respectively. Biopsy-proven treated acute rejection occurred in six everolimus and four control heart transplant patients (P=0.54). In total, 138 everolimus patients (98.6%) and 127 control patients (89.4%) experienced one or more adverse event (P=0.002). Serious adverse events occurred in 66 everolimus patients (46.8%) and 44 controls (31.0%) (P=0.02). Conclusion. Introduction of everolimus with CNI reduction offers a significant improvement in renal function in maintenance heart and lung transplant recipients. The greatest benefit is observed in patients with a shorter time since transplantation.
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| 19. |
- Gullestad, Lars, et al.
(författare)
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Two-Year Outcomes in Thoracic Transplant Recipients After Conversion to Everolimus With Reduced Calcineurin Inhibitor Within a Multicenter, Open-Label, Randomized Trial.
- 2010
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Ingår i: Transplantation. - : Williams and Wilkins. - 1534-6080 .- 0041-1337. ; 90:12, s. 1581-1589
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND.: Use of the mammalian target of rapamycin inhibitor everolimus with an accompanying reduction in calcineurin inhibitor (CNI) exposure has shown promise in preserving renal function in maintenance thoracic transplant patients, but robust, long-term data are required. METHODS.: In a prospective, open-label, multicenter study, thoracic transplant recipients more than or equal to 1 year posttransplant with mild-to-moderate renal insufficiency were randomized to continue their current CNI-based immunosuppression or convert to everolimus with predefined CNI exposure reduction. After a 12-month core trial, patients were followed up to month 24 after randomization. RESULTS.: Of 245 patients who completed the month 12 visit, 235 patients (108 everolimus and 127 controls) entered the 12-month extension phase. At month 24, mean measured glomerular filtration rate had increased by 3.2±12.3 mL/min from the point of randomization in everolimus-treated patients and decreased by 2.4±9.0 mL/min in controls (P<0.001), a difference that was significant within both the heart and lung transplant subpopulations. During months 12 to 24, 5.6% of everolimus patients and 3.1% of controls experienced biopsy-proven acute rejection (P=0.76). There were no significant differences in the rate of adverse events or serious adverse events (including pneumonia) between groups during months 12 to 24. CONCLUSIONS.: Converting maintenance thoracic transplant recipients to everolimus with low-exposure CNI results in a renal benefit that is sustained to 2 years postconversion, with significantly improved measured glomerular filtration rate in both heart and lung transplant patients. Despite reductions of more than 50% in CNI exposure, there was no marked loss of efficacy. The safety profile of the everolimus-based regimen was acceptable.
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| 20. |
- Gunawidjaja, Philips N., et al.
(författare)
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Quantifying apatite formation and cation leaching from mesoporous bioactive glasses in vitro : a SEM, solid-state NMR and powder XRD study
- 2012
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 22:15, s. 7214-7223
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Tidskriftsartikel (refereegranskat)abstract
- By employing solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy coupled with energy-dispersive X-ray (EDX) spectroscopy, we compare the biomimetic growth of calcium hydroxyapatite (HA) from an ordered mesoporous bioactive glass (MBG) in simulated body fluid (SBF) and buffered water solutions. For the latter medium, we also examine the effects of using two different MBG concentrations. We evaluate the predicting powers of PXRD and P-31 NMR for directly quantifying the relative amounts of biomimetic amorphous calcium phosphate (ACP) and HA: we observe a very good agreement between the two analytical techniques. Thanks to their mesoporous channel system, fluids readily penetrate throughout sub-mm sized MBG grains, as evidenced by EDX. The latter revealed distinct element-mappings across the material after its exposure to SBF compared to water. Under our in vitro conditions involving relatively high MBG-loadings in the solutions, the HA formation reduces in SBF relative to buffered water, particularly for increasing MBG concentration. These features stem from a high [Ca2+]/[PO43-] ratio resulting in the fluid medium, which retards the HA crystallization by inducing a rapid ACP precipitation and an accompanying depletion of phosphate ions in the solution. This has bearings on the design of bioactivity comparisons of bioglasses exhibiting significantly different cation compositions.
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