| 1. |
- Hammaréus, Filip, et al.
(författare)
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Wall shear stress measured with 4D flow CMR correlates with biomarkers of inflammation and collagen synthesis in mild-to-moderate ascending aortic dilation and tricuspid aortic valves
- 2024
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Ingår i: European Heart Journal Cardiovascular Imaging. - : OXFORD UNIV PRESS. - 2047-2404 .- 2047-2412.
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Tidskriftsartikel (refereegranskat)abstract
- Aims Understanding the mechanisms underlying ascending aortic dilation is imperative for refined risk stratification of these patients, particularly among incidentally identified patients, most commonly presenting with tricuspid valves. The aim of this study was to explore associations between ascending aortic haemodynamics, assessed using four-dimensional flow cardiovascular magnetic resonance imaging (4D flow CMR), and circulating biomarkers in aortic dilation. Methods and results Forty-seven cases with aortic dilation (diameter >= 40 mm) and 50 sex-and age-matched controls (diameter < 40 mm), all with tricuspid aortic valves, underwent 4D flow CMR and venous blood sampling. Associations between flow displacement, wall shear stress (WSS), and oscillatory shear index in the ascending aorta derived from 4D flow CMR, and biomarkers including interleukin-6, collagen type I alpha 1 chain, metalloproteinases (MMPs), and inhibitors of MMPs derived from blood plasma, were investigated. Cases with dilation exhibited lower peak systolic WSS, higher flow displacement, and higher mean oscillatory shear index compared with controls without dilation. No significant differences in biomarkers were observed between the groups. Correlations between haemodynamics and biomarkers were observed, particularly between maximum time-averaged WSS and interleukin-6 (r = 0.539, P < 0.001), and maximum oscillatory shear index and collagen type I alpha 1 chain (r = -0.575, P < 0.001 in cases). Conclusion Significant associations were discovered between 4D flow CMR derived whole-cardiac cycle WSS and circulating biomarkers representing inflammation and collagen synthesis, suggesting an intricate interplay between haemodynamics and the processes of inflammation and collagen synthesis in patients with early aortic dilation and tricuspid aortic valves.
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| 2. |
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| 3. |
- Belcastro, Luigi, et al.
(författare)
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Beneath the skin: multi-frequency SFDI to detect thin layers of skin using light scattering
- 2023
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Ingår i: PHOTONICS IN DERMATOLOGY AND PLASTIC SURGERY 2023. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9781510658097 - 9781510658103
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Konferensbidrag (refereegranskat)abstract
- Wound healing assessment is usually performed visually by a trained physician. This type of evaluation is very subjective and returns limited information about the wound progression. In contrast, optical imaging techniques are non-invasive ways to quantitatively measure biological parameters. Spatial frequency domain imaging (SFDI) is an optical technique that exploits sinusoidal patterns of light with multiple spatial frequencies to measure the tissue frequency-specific response, from which the absorption and scattering coefficient of the material can be derived. While SFDI is based on models of light transport that assume the tissue is homogeneous, skin is composed by several layer with very different optical properties. An underutilized property of SFDI, however, is that the spatial frequency of the patterns determines the penetration depth of photons in the tissue. By using multiple ranges of spatial frequencies, we are developing a means to obtain morphological data from different volumes of tissue. This data is used to reconstruct the optical properties in depth, allowing us to differentiate between different thin layers of tissue. In this study we have developed a 2-layer optical phantom model with realistic optical properties and dimensions, that mimics the physiology of wound healing. We have used this physical model to validate the accuracy of this approach in obtaining layer specific optical properties.
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| 4. |
- Belcastro, Luigi, et al.
(författare)
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Handheld multispectral imager for quantitative skin assessment in low resource settings
- 2020
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Ingår i: Journal of Biomedical Optics. - : SPIE - The International Society for Optics and Photonics. - 1083-3668 .- 1560-2281. ; 25:8
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Tidskriftsartikel (refereegranskat)abstract
- Significance: Spatial frequency domain imaging (SFDI) is a quantitative imaging method to measure absorption and scattering of tissue, from which several chromophore concentrations (e.g., oxy-/deoxy-/meth-hemoglobin, melanin, and carotenoids) can be calculated. Employing a method to extract additional spectral bands from RGB components (that we named cross-channels), we designed a handheld SFDI device to account for these pigments, using low-cost, consumer-grade components for its implementation and characterization.Aim: With only three broad spectral bands (red, green, blue, or RGB), consumer-grade devices are often too limited. We present a methodology to increase the number of spectral bands in SFDI devices that use RGB components without hardware modification.Approach: We developed a compact low-cost RGB spectral imager using a color CMOS camera and LED-based mini projector. The components’ spectral properties were characterized and additional cross-channel bands were calculated. An alternative characterization procedure was also developed that makes use of low-cost equipment, and its results were compared. The device performance was evaluated by measurements on tissue-simulating optical phantoms and in-vivo tissue. The measurements were compared with another quantitative spectroscopy method: spatial frequency domain spectroscopy (SFDS).Results: Out of six possible cross-channel bands, two were evaluated to be suitable for our application and were fully characterized (520 ± 20 nm; 556 ± 18 nm). The other four cross-channels presented a too low signal-to-noise ratio for this implementation. In estimating the optical properties of optical phantoms, the SFDI data have a strong linear correlation with the SFDS data (R2 = 0.987, RMSE = 0.006 for μa, R2 = 0.994, RMSE = 0.078 for μs′).Conclusions: We extracted two additional spectral bands from a commercial RGB system at no cost. There was good agreement between our device and the research-grade SFDS system. The alternative characterization procedure we have presented allowed us to measure the spectral features of the system with an accuracy comparable to standard laboratory equipment.
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| 5. |
- Belcastro, Luigi, 1992-
(författare)
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Multi-frequency SFDI : depth-resolved scattering models of wound healing
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With optical techniques, we refer to a group of methods that use of light to perform measurements on matter. Spatial frequency domain imaging (SFDI) is an optical technique that operates in the spatial frequency domain. The technique involves using sinusoidal patterns of light for illumination, to study the reflectance of the target based on the spatial frequency (ƒx) of the patterns. By analysing the frequency-specific response with the aid of light transport models, we are able to determine the intrinsic optical properties of the material, such as the absorption coefficient (μa) and reduced scattering coefficient (μ's) In biological applications, these optical properties can be correlated to physiological structures and molecules, providing a useful tool for researchers and clinicians alike in understanding the phenomena happening in biological tissue. The objective of this work is to contribute to the development of SFDI, so that the technique can be used as a diagnostic tool to study the process of wound healing in tissue. In paper I we introduce the concept of cross-channels, given by the spectral overlap of the broadband LED light sources and the RGB camera sensors used in the SFDI instrumentation. The purpose of cross-channels is to improve the limited spectral information of RGB devices, allowing to detect a larger number of biological molecules. One of the biggest limitations of SFDI is that it works on the assumption of light diffusing through a homogeneous, thick layer of material. This assumption loses validity when we want to examine biological tissue, which comprises multiple thin layers with different properties. In paper IV we have developed a new method to process SFDI data that we call multi-frequency SFDI. In this new approach, we make use of the different penetration depth of the light patterns depending on their ƒx to obtain depth-sensitive measurements. We also defined a 2-layer model of light scattering that imitates the physiology of a wound, to calculate the partial volume contributions to μ's of the single layers. The 2-layer model is based on analytical formulations of light fluence. We compared the performance of three fluence models, one of which we have derived ourselves as an improvement over an existing formulation. In paper II we were able to test our new multi-frequency SFDI method by participating in an animal study on stem-cells based regenerative therapies. We contributed by performing SFDI measurements on healing wounds, in order to provide an additional evaluation metric that complemented the clinical evaluation and cell histology performed in the study. The analysis of the SFDI data at different ƒx highlighted different processes happening on the surface compared to the deeper tissue. In paper V we further refine the technique introduced in paper IV by developing an inverse solver algorithm to isolate the thickness of the thin layer and the layer-specific μ's. The reconstructed parameters were tested both on thin silicone optical phantoms and ex-vivo burn wounds treated with stem cells.
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| 6. |
- Bergstrand, Sara, et al.
(författare)
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Association between cardiovascular risk profile and impaired microvascular function in a Swedish middle-aged cohort (the SCAPIS study)
- 2024
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Ingår i: European Journal of Preventive Cardiology. - : OXFORD UNIV PRESS. - 2047-4873 .- 2047-4881.
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Tidskriftsartikel (refereegranskat)abstract
- Aims The aim was to investigate the relationship between microvascular function, cardiovascular risk profile, and subclinical atherosclerotic burden. Methods and results The study enrolled 3809 individuals, 50-65 years old, participating in the population-based observational cross-sectional Swedish CArdioPulmonary bioImage Study. Microvascular function was assessed in forearm skin using an arterial occlusion and release protocol determining peak blood oxygen saturation (OxyP). Cardiovascular risk was calculated using the updated Systematic Coronary Risk Evaluation [SCORE2; 10-year risk of fatal and non-fatal cardiovascular disease (CVD) events]. The OxyP was compared with coronary artery calcification score (CACS) and to plaques in the carotid arteries. Individuals with OxyP values in the lowest quartile (Q1; impaired microvascular function) had a mean SCORE2 of 5.8% compared with 3.8% in those with the highest values of OxyP (Q4), a relative risk increase of 53%. The risk of having a SCORE2 > 10% was five times higher for those in Q1 (odds ratio: 4.96, 95% confidence interval: 2.76-8.93) vs. Q4 when adjusting for body mass index and high-sensitivity C-reactive protein. The OxyP was lower in individuals with CACS > 0 and in those with both carotid plaques and CACS > 0, compared with individuals without subclinical atherosclerotic burdens (87.5 +/- 5.6% and 86.9 +/- 6.0%, vs. 88.6 +/- 5.8%, P < 0.01). Conclusion In a population without CVD or diabetes mellitus, impaired microvascular function is associated with cardiovascular risk profiles such as higher SCORE2 risk and CACS. We suggest that OxyP may serve as a microcirculatory functional marker of subclinical atherosclerosis and CVD risk that is not detected by structural assessments.
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| 7. |
- Callaghan, Terry V., et al.
(författare)
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Ecosystem change and stability over multiple decades in the Swedish subarctic : complex processes and multiple drivers
- 2013
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 368:1624
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Tidskriftsartikel (refereegranskat)abstract
- The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in trees and shrubs (up to 600%). There has been an increase in abundance of aspen and large changes in other plant communities responding to wetland area increases resulting from permafrost thaw. Populations of herbivores have responded to varying management practices and climate regimes, particularly changing snow conditions. While it is difficult to generalize and scale-up the site-specific changes in ecosystems, this very site-specificity, combined with projections of change, is of immediate relevance to local stakeholders who need to adapt to new opportunities and to respond to challenges. Furthermore, the relatively small area and its unique datasets are a microcosm of the complexity of Arctic landscapes in transition that remains to be documented.
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| 8. |
- Campbell, PJ, et al.
(författare)
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Pan-cancer analysis of whole genomes
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 578:7793, s. 82-
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1–3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4–5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10–18.
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| 9. |
- Fernlund, Eva, et al.
(författare)
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Hereditary hypertrophic cardiomyopathy in children and young adults—The value of reevaluating and expanding gene panel analyses
- 2020
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Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Sudden cardiac death (SCD) and early onset cardiomyopathy (CM) in the young will always lead to suspicion of an underlying genetic disorder. Incited by the rapid advances in genetic testing for disease we have revisited families, which previously tested “gene-negative” for familial predominantly pediatric CM, in hopes of finding a causative gene variant. Methods: 10 different families with non-syndromic pediatric CM or hypertrophic cardiomyopathy (HCM) with severe disease progression and/or heredity for HCM/CM related SCD with “gene-negative” results were included. The index patient underwent genetic testing with a recently updated gene panel for CM and SCD. In case of failure to detect a pathogenic variant in a relevant gene, the index patient and both parents underwent clinical (i.e., partial) exome sequencing (trio-exome) in order to catch pathogenic variants linked to the disease in genes that were not included in the CM panel. Results: The mean age at clinical presentation of the 10 index cases was 12.5 years (boys 13.4 years, n = 8; girls 9 years, n = 2) and the family history burden was 33 HCM/CM cases including 9 HCM-related SCD and one heart transplantation. In 5 (50%) families we identified a genetic variant classified as pathogenic or likely pathogenic, in accordance with the American College of Medical Genetics and Genomics (ACMG) criteria, in MYH7 (n = 2), RBM20, ALPK3, and PGM1, respectively, and genetic variants of unknown significance (VUS) segregating with the disease in an additional 3 (30%) families, in MYBPC3, ABCC9, and FLNC, respectively. Conclusion: Our results show the importance of renewed thorough clinical assessment and the necessity to challenge previous genetic test results with more comprehensive updated gene panels or exome sequencing if the initial test failed to identify a causative gene for early onset CM or SCD in children. In pediatric cardiomyopathy cases when the gene panel still fails to detect a causative variant, a trio exome sequencing strategy might resolve some unexplained cases, especially if a multisystemic condition is clinically missed.
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| 10. |
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| 11. |
- Haj-Hosseini, Neda, 1980-, et al.
(författare)
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Interactive remote electrical safety laboratory module in biomedical engineering education
- 2024
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Ingår i: Education and Information Technologies. - : Springer. - 1360-2357 .- 1573-7608.
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Tidskriftsartikel (refereegranskat)abstract
- To enable interactive remote education on electrical safety in biomedical engineering, a real-life problem-based laboratory module is proposed, implemented and evaluated. The laboratory module was implemented in a freestanding distance course in hospital safety for three consecutive years and was based on electrical safety for medical devices, where standard equipment existing in most hospitals could be used. The course participants were from a total of 42 geographical locations in or near Sweden. To allow a high level of interaction, especially among peer students, a graphical digital platform (Gather Town) was used. The digital platform was additionally used in two group work sessions. The experience of the participants in terms of usefulness and satisfaction was rated on a range of [-2, 2] using a van der Laan 5-point Likert-based acceptance scale questionnaire. The laboratory module overall was scored 4.1/5 by the participants (n= 29) in the final course assessments. The evaluation of the digital platform alone showed that in the first usage instance, the participants (n=21) found the platform to be useful (0.54±0.67) and satisfactory (0.37±0.60). The participants’ experience of the digital platform improved when comparing two identical group work assignments so that ratings of usefulness and satisfaction were 1.11±0.59 and 1±0.71, respectively, after they had used it in the second group work session (n=38). This study provides an instance of an interactive remote electrical safety laboratory module that is envisioned to contribute to further implementations of sustainable education in biomedical engineering.
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| 12. |
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| 13. |
- Iredahl, Fredrik, et al.
(författare)
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Local Response and Barrier Recovery in Elderly Skin Following the Application of High-Density Microarray Patches
- 2022
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Ingår i: Vaccines. - : MDPI. - 2076-393X. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- The high-density microneedle array patch (HD-MAP) is a promising alternative vaccine delivery system device with broad application in disease, including SARS-CoV-2. Skin reactivity to HD-MAP applications has been extensively studied in young individuals, but not in the >65 years population, a risk group often requiring higher dose vaccines to produce protective immune responses. The primary aims of the present study were to characterise local inflammatory responses and barrier recovery to HD-MAPs in elderly skin. In twelve volunteers aged 69-84 years, HD-MAPs were applied to the forearm and deltoid regions. Measurements of transepidermal water loss (TEWL), dielectric permittivity and erythema were performed before and after HD-MAP application at t = 10 min, 30 min, 48 h, and 7 days. At all sites, TEWL (barrier damage), dielectric permittivity (superficial water);, and erythema measurements rapidly increased after HD-MAP application. After 7 days, the mean measures had recovered toward pre-application values. The fact that the degree and chronology of skin reactivity and recovery after HD-MAP was similar in elderly skin to that previously reported in younger adults suggests that the reactivity basis for physical immune enhancement observed in younger adults will also be achievable in the older population.
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| 14. |
- Johansson, Maria U, et al.
(författare)
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Structure, specificity, and mode of interaction for bacterial albumin-binding modules.
- 2002
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Ingår i: Journal of Biological Chemistry. - 1083-351X .- 0021-9258. ; 277:10, s. 8114-8120
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Tidskriftsartikel (refereegranskat)abstract
- We have determined the solution structure of an albumin binding domain of protein G, a surface protein of group C and G streptococci. We find that it folds into a left handed three-helix bundle similar to the albumin binding domain of protein PAB from Peptostreptococcus magnus. The two domains share 59% sequence identity, are thermally very stable, and bind to the same site on human serum albumin. The albumin binding site, the first determined for this structural motif known as the GA module, comprises residues spanning the first loop to the beginning of the third helix and includes the most conserved region of GA modules. The two GA modules have different affinities for albumin from different species, and their albumin binding patterns correspond directly to the host specificity of C/G streptococci and P. magnus, respectively. These studies of the evolution, structure, and binding properties of the GA module emphasize the power of bacterial adaptation and underline ecological and medical problems connected with the use of antibiotics.
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| 15. |
- Jonasson, Hanna, et al.
(författare)
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Absorption and reduced scattering coefficients in epidermis and dermis from a Swedish cohort study
- 2023
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Ingår i: Journal of Biomedical Optics. - : SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS. - 1083-3668 .- 1560-2281. ; 28:11
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Tidskriftsartikel (refereegranskat)abstract
- Significance Knowledge of optical properties is important to accurately model light propagation in tissue, but in vivo reference data are sparse.Aim The aim of our study was to present in vivo skin optical properties from a large Swedish cohort including 3809 subjects using a three-layered skin model and spatially resolved diffuse reflectance spectroscopy (Periflux PF6000 EPOS).Approach Diffuse reflectance spectra (475 to 850 nm) at 0.4 and 1.2 mm source-detector separations were analyzed using an inverse Monte Carlo method. The model had one epidermis layer with variable thicknesses and melanin-related absorptions and two dermis layers with varying hemoglobin concentrations and equal oxygen saturations. The reduced scattering coefficient was equal across all layers.Results Median absorption coefficients (mm (- 1)) in the upper dermis ranged from 0.094 at 475 nm to 0.0048 at 850 nm and similarly in the lower dermis from 0.059 to 0.0035. The reduced scattering coefficient (mm( - 1)) ranged from 3.22 to 1.20, and the sampling depth (mm) ranged from 0.23 to 0.38 (0.4 mm separation) and from 0.49 to 0.68 (1.2 mm separation). There were differences in optical properties across sex, age groups, and BMI categories.Conclusions Reference material for skin optical properties is presented.
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| 16. |
- Jonasson, Hanna, et al.
(författare)
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Assessment of the microcirculation using combined model based diffuse reflectance spectroscopy and laser Doppler flowmetry
- 2015
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Ingår i: 16th Nordic-Baltic Conference on Biomedical Engineering. - Cham : Springer. - 9783319129662 - 9783319129679 ; , s. 52-54
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Konferensbidrag (refereegranskat)abstract
- By using a combined inverse model for diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) the tissue fraction of red blood cells (RBCs), their oxygenation and speed-resolved perfusion are estimated in absolute units. DRS spectra (450 to 850 nm) are measured at two source-detector distances; 0.4 and 1.2 mm. LDF spectra are measured at 1.2 mm, integrated in the same fiber-optic probe. Inverse Monte Carlo technique and an adaptive tissue model is used to quantify the microcirculatory parameters. Measurements were done during venous occlusion of the tissue. The model fitting yields a good spectral fit for the two DRS spectra and the LDF spectrum. The physiological responses regarding for example which speed regions respond to provocations follows a priori expectations. The combined model gives quantitative measures of RBC tissue fraction, oxygenation and speed resolved perfusion from the same sampling volume which gives new opportunities to interpret data.
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| 17. |
- Jonasson, Hanna, 1981-, et al.
(författare)
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In vivo characterization of light scattering properties of human skin in the 475- to 850-nm wavelength range in a Swedish cohort
- 2018
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Ingår i: Journal of Biomedical Optics. - : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 23:12
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Tidskriftsartikel (refereegranskat)abstract
- We have determined in vivo optical scattering properties of normal human skin in 1734 subjects, mostly with fair skin type, within the Swedish CArdioPulmonary bioImage Study. The measurements were performed with a noninvasive system, integrating spatially resolved diffuse reflectance spectroscopy and laser Doppler flowmetry. Data were analyzed with an inverse Monte Carlo algorithm, accounting for both scattering, geometrical, and absorbing properties of the tissue. The reduced scattering coefficient was found to decrease from 3.16 ± 0.72 to 1.13 ± 0.27 mm-1 (mean ± SD) in the 475- to 850-nm wavelength range. There was a negative correlation between the reduced scattering coefficient and age, and a significant difference between men and women in the reduced scattering coefficient as well as in the fraction of small scattering particles. This large study on tissue scattering with mean values and normal variation can serve as a reference when designing diagnostic techniques or when evaluating the effect of therapeutic optical systems.
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| 18. |
- Jonasson, Hanna, 1981-
(författare)
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Model-based quantitative assessment of skin microcirculatory blood flow and oxygen saturation
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The microcirculation, involving the smallest vessels in the body, is where the oxygen transport to all tissue occurs. Evaluating microcirculatory parameters is, therefore, important and involves the quantification of oxygen content of red blood cells (RBCs), the amount of RBCs and their speed.Diffuse reflectance spectroscopy (DRS) can be used to estimate blood oxygen saturation and fraction of RBCs in tissue since oxygenated and deoxygenated blood have different light absorption characteristics. By illuminating the skin with white light and detecting the spectrum of the backscattered light, tissue absorption and scattering can be assessed. Laser Doppler flowmetry (LDF) is a technique to measure blood flow in tissue. When laser light encounter moving objects in tissue, i.e. RBCs, the light is Doppler shifted, which can be detected and used to calculate tissue perfusion (the fraction of moving RBCs times their speed). With a small distance between light source and detector, both techniques measure superficially where most vessels are microcirculatory vessels. Photon transport in tissue can be simulated with Monte Carlo techniques and the simulations form the basis of modeled DRS and LDF spectra. The estimated microcirculatory parameters are given by the model that best describe measured DRS and LDF data.This thesis describes the development and the evaluation of an optical method to simultaneously measure oxygen saturation, RBC tissue fraction and speed resolved perfusion in absolute units by integrating DRS and LDF. By combining DRS and LDF into one system with a common tissue model, the two modalities can benefit from each other’s strengths. Different calibration methods and model assumptions for the system were evaluated in optical phantoms and in skin measurements. A simple calibration method with two detector distances for DRS was found adequate to accurately estimate absorption and scattering in optical phantoms. It was also necessary to model blood located in vessels, rather than homogeneously distributed in the skin, to obtain accurate parameter estimates. The system was evaluated in healthy subjects during standard provocations, where the parameters were in agreement with other studies and followed an expected pattern during the provocations. In patients with diabetes type 2, tissue fraction of RBCs and nutritive blood flow were reduced in baseline compared to healthy controls. These differences were not related to prevalence of microalbuminuria, a marker sign of microvascular complications in the kidneys.A combined system with DRS and LDF enables a more comprehensive assessment of the microcirculation by measuring oxygen saturation, RBC tissue fraction and speed resolved perfusion simultaneously and in absolute units. This system has clinical potential to assist in the evaluation of the microcirculation both in healthy and diseased individuals.
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| 19. |
- Jonasson, Hanna, et al.
(författare)
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Normative data and the influence of age and sex on microcirculatory function in a middle-aged cohort: results from the SCAPIS study
- 2020
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Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : AMER PHYSIOLOGICAL SOC. - 0363-6135 .- 1522-1539. ; 318:4, s. H908-H915
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to assess normative values for comprehensive forearm skin microcirculatory function: oxygen saturation, tissue fraction of red blood cells (RBCs), and speed-resolved perfusion. Furthermore, to examine the influence of age and sex on microcirculatory function. Measurements were performed using a noninvasive probe-based system, including diffuse reflectance spectroscopy and laser-Doppler flowmetry, yielding output data in absolute units. The study was conducted within the Swedish CArdioPulmonary BioImage Study (SCAPIS) and included 1,765 men and women aged 50-65 yr from the Linkoping general population. Normative values are given at baseline, at the end of a 5-min occlusion of the brachial artery and during hyperemia after occlusion release. We found a consistent age distribution, in which the oldest individuals had the lowest peak oxygen saturation (P < 0.001) and the highest baseline low-speed perfusion (P < 0.001). Women had higher peak oxygen saturation (P < 0.001), lower RBC tissue fraction, in general (P < 0.001), lower baseline perfusion in all speed regions (P = 0.01). and lower peak high-speed perfusion at hyperemia (P < 0.001). The normative data can be used as reference values in future studies of disease-specific populations. The results show that age and sex are important aspects to consider in studies of microvascular function. Women and younger age were factors associated with higher peak oxygen saturation after ischemia. This is a novel parameter that reflects overall microcirculatory function associated with vascular dilation capacity. NEW & NOTEWORTHY This study expands experimental microcirculatory research to clinical use by providing normative values on microcirculatory function in a large population-based cohort. Women and younger age were factors associated with higher peak oxygen saturation after ischemia, which implies that age and sex are important aspects to consider in studies of micmvascular function. This study is the first step toward using microcirculatory assessment as a tool to improve diagnosis. prognosis. and treatment in disease-specific populations.
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| 20. |
- Jonasson, Hanna, et al.
(författare)
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Oxygen saturation, red blood cell tissue fraction and speed resolved perfusion — A new optical method for microcirculatory assessment
- 2015
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 102, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a new fiber-optic system that combines diffuse reflectance spectroscopy (DRS) and laser Doppler Flowmetry (LDF) for a multi-modal assessment of the microcirculation. Quantitative data is achieved with an inverse Monte Carlo algorithm based on an individually adaptive skin model. The output parameters are calculated from the model and given in absolute units: hemoglobin oxygen saturation (%), red blood cell (RBC) tissue fraction (%), and the speed resolved RBC perfusion separated into three speed regions; 0–1 mm/s, 1–10 mm/s and above 10 mm/s (% mm/s). The aim was to explore microcirculatory parameters using the new optical method, integrating DRS and LDF in a joint skin model, during local heating of the dorsal foot and venous and arterial occlusion of the forearm in 23 healthy subjects (age 20–28 years). There were differences in the three speed regions in regard to blood flow changes due to local heating, where perfusion for high speeds increased the most. There was also a high correlation between changes in oxygenation and changes in perfusion for higher speeds. Oxygen saturation at baseline was 44% on foot, increasing to 83% at plateau after heating. The larger increase in perfusion for higher speeds than for lower speeds together with the oxygenation increase during thermal provocation, shows a local thermoregulatory blood flow in presumably arteriolar dermal vessels. In conclusion, there are improved possibilities to assess microcirculation using integrated DRS and LDF in a joint skin model by enabling both oxygenation and speed resolved blood flow assessment simultaneously and in the same skin site. Output parameters in absolute units may also yield new insights about the microcirculatory system.
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| 21. |
- Jonasson, Hanna, et al.
(författare)
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Post-ischemic skin peak oxygen saturation is associated with cardiovascular risk factors: a Swedish cohort study
- 2022
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Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to explore the associations between skin microcirculatory function and established cardiovascular risk factors in a large Swedish cohort. As part of the Swedish CArdioPulmonary bioImage Study (SCAPIS), microcirculatory data were acquired at Linko center dot ping University hospital, Linko center dot ping, Sweden during 2016-2017. The subjects, aged 50-64 years, were randomly selected from the national population register. Microcirculatory reactivity was assessed using a 5-min arterial occlusion-release protocol. Comprehensive skin microcirculatory data were continuously acquired by using a fiberoptic probe placed on the lower right arm. After exclusion of missing data (208), 1557 subjects were remaining. Among the parameters, skin microcirculatory peak oxygen saturation after occlusion release, had the strongest relationship to the cardiovascular risk factors. The linear associations between peak oxygen saturation and cardiovascular risk factors were analyzed adjusted for age and sex. We found a negative association with peak oxygen saturation (standardized regression coefficient) for blood pressure (systolic-0.05 (95% CI:-0.10;-0.003) and diastolic-0.05 (-0.10;-0.003)), BMI-0.18 (-0.23;-0.13), waist circumference (males-0.20 (-0.32;-0.16), females-0.18 (-0.25;-0.11)), prevalent diabetes-0.31 (-0.49;-0.12), hypertension-0.30 (-0.42;-0.18), dyslipidemia-0.24 (-0.40;-0.09), fasting glucose level-0.06 (-0.12;-0.01), HbA1c-0.07 (-0.12;-0.02), triglyceride level-0.09 (-0.14;-0.04), hsCRP-0.12 (-0.17;-0.07), and current smoker versus never smoked-0.50 (-0.67;-0.34). A positive association with peak oxygen saturation was found for cholesterol level 0.05 (0.005; 0.11) and HDL 0.11 (0.06; 0.17). This is the first study showing that post-ischemic skin microvascular peak oxygen saturation is associated with virtually all established cardiovascular risk factors in a population-based middle-aged cohort.
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| 22. |
- Jonasson, Hanna, et al.
(författare)
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Skin microvascular endothelial dysfunction is associated with type 2 diabetes independently of microalbuminuria and arterial stiffness
- 2017
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Ingår i: Diabetes & Vascular Disease Research. - : SAGE PUBLICATIONS LTD. - 1479-1641 .- 1752-8984. ; 14:4, s. 363-371
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Tidskriftsartikel (refereegranskat)abstract
- Skin and kidney microvascular functions may be affected independently in diabetes mellitus. We investigated skin microcirculatory function in 79 subjects with diabetes type 2, where 41 had microalbuminuria and 38 not, and in 41 age-matched controls. The oxygen saturation, fraction of red blood cells and speed-resolved microcirculatory perfusion (% red blood cells x mm/s) divided into three speed regions: 0-1, 1-10 and above 10 mm/s, were assessed during baseline and after local heating of the foot with a new device integrating diffuse reflectance spectroscopy and laser Doppler flowmetry. Arterial stiffness was assessed as carotid-femoral pulse wave velocity. Subjects with diabetes and microalbuminuria had significantly higher carotid-femoral pulse wave velocity compared to subjects without microalbuminuria and to controls. The perfusion for speeds 0-1 mm/s and red blood cell tissue fraction were reduced in subjects with diabetes at baseline and after heating, independent of microalbuminuria. These parameters were correlated to HbA1c. In conclusion, the reduced nutritive perfusion and red blood cell tissue fraction in type 2 diabetes were related to long-term glucose control but independent of microvascular changes in the kidneys and large-vessel stiffness. This may be due to different pathogenic pathways in the development of nephropathy, large-vessel stiffness and cutaneous microvascular impairment.
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| 23. |
- Jonasson, Hanna, et al.
(författare)
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Validation of speed-resolved laser Doppler perfusion in a multimodal optical system using a blood-flow phantom
- 2019
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Ingår i: Journal of Biomedical Optics. - : SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS. - 1083-3668 .- 1560-2281. ; 24:9
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Tidskriftsartikel (refereegranskat)abstract
- The PeriFlux 6000 EPOS system combines diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) for the assessment of oxygen saturation (expressed in percentage), red blood cell (RBC) tissue fraction (expressed as volume fraction, %RBC), and perfusion (%RBC x mm/s) in the microcirculation. It also allows the possibility of separating the perfusion into three speed regions (0 to 1, 1 to 10, and amp;gt;10 mm/s). We evaluate the speed-resolved perfusion components, i.e., the relative amount of perfusion within each speed region, using a blood-flow phantom. Human blood was pumped through microtubes with an inner diameter of 0.15 mm. Measured DRS and LDF spectra were compared to Monte Carlo-simulated spectra in an optimization routine, giving the best-fit parameters describing the measured spectra. The root-mean-square error for each of the three speed components (0 to 1, 1 to 10, and amp;gt;10 mm/s, respectively) when describing the blood-flow speed in the microtubes was 2.9%, 8.1%, and 7.7%. The presented results show that the system can accurately discriminate blood perfusion originating from different blood-flow speeds, which may enable improved measurement of healthy and dysfunctional microcirculatory flow. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.
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| 24. |
- Jonasson, Hanna, 1981-, et al.
(författare)
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Water and hemoglobin modulated gelatin-based phantoms to spectrally mimic inflamed tissue in the validation of biomedical techniques and the modeling of microdialysis data
- 2022
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Ingår i: Journal of Biomedical Optics. - Bellingham, WA, United States : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 27:7
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Tidskriftsartikel (refereegranskat)abstract
- Significance: Tissue simulating phantoms are an important part of validating biomedical optical techniques. Tissue pathology in inflammation and oedema involves changes in both water and hemoglobin fractions.Aim: We present a method to create solid gelatin-based phantoms mimicking inflammation and oedema with adjustable water and hemoglobin fractions.Approach: One store-bought gelatin and one research grade gelatin were evaluated. Different water fractions were obtained by varying the water-to-gelatin ratio. Ferrous stabilized human hemoglobin or whole human blood was added as absorbers, and the stability and characteristics of each were compared. Intralipid® was used as the scatterer. All phantoms were characterized using spatial frequency domain spectroscopy.Results: The estimated water fraction varied linearly with expected values (R2 = 0.96 for the store-bought gelatin and R2 = 0.99 for the research grade gelatin). Phantoms including ferrous stabilized hemoglobin stayed stable up to one day but had methemoglobin present at day 0. The phantoms with whole blood remained stable up to 3 days using the store-bought gelatin.Conclusions: A range of physiological relevant water fractions was obtained for both gelatin types, with the stability of the phantoms including hemoglobin differing between the gelatin type and hemoglobin preparation. These low-cost phantoms can incorporate other water-based chromophores and be fabricated as thin sheets to form multilayered structures.
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| 25. |
- Jönsson, Simon, et al.
(författare)
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Increased Levels of Leukocyte-Derived MMP-9 in Patients with Stable Angina Pectoris
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Objective: There is a growing interest for matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in plasma as novel biomarkers in coronary artery disease (CAD). We aimed to identify the sources of MMP-8, MMP-9, TIMP-1 and TIMP-2 among peripheral blood cells and further explore whether gene expression or protein release was altered in patients with stable angina pectoris (SA). Methods: In total, plasma MMP-9 was measured in 44 SA patients and 47 healthy controls. From 10 patients and 10 controls, peripheral blood mononuclear cells (PBMC) and neutrophils were isolated and stimulated ex vivo. MMPs, TIMPs and myeloperoxidase were measured in plasma and supernatants by ELISA. The corresponding gene expression was measured by real-time PCR. Results: Neutrophils were the dominant source of MMP-8 and MMP-9. Upon moderate stimulation with IL-8, the neutrophil release of MMP-9 was higher in the SA patients compared with controls (p andlt; 0.05). In PBMC, the TIMP-1 and MMP-9 mRNA expression was higher in SA patients compared with controls, p andlt; 0.01 and 0.05, respectively. There were no differences in plasma levels between patients and controls except for TIMP-2, which was lower in patients, p andlt; 0.01. Conclusion: Measurements of MMPs and TIMPs in plasma may be of limited use. Despite similar plasma levels in SA patients and controls, the leukocyte-derived MMP-9 and TIMP-1 are significantly altered in patients. The findings indicate that the leukocytes are more prone to release and produce MMP-9 in symptomatic and angiographically verified CAD-a phenomenon that may have clinical implications in the course of disease.
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| 26. |
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| 27. |
- Kissopoulou, Antheia, et al.
(författare)
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Monozygotic twins with myocarditis and a novel likely pathogenic desmoplakin gene variant
- 2020
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Ingår i: ESC Heart Failure. - : Wiley. - 2055-5822. ; 7:3, s. 1210-1216
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Tidskriftsartikel (refereegranskat)abstract
- Myocarditis most often affects otherwise healthy athletes and is one of the leading causes of sudden death in children and young adults. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically determined heart muscle disorder with increased risk for paroxysmal ventricular arrhythmias and sudden cardiac death. The clinical picture of myocarditis and ARVC may overlap during the early stages of cardiomyopathy, which may lead to misdiagnosis. In the literature, we found several cases that presented with episodes of myocarditis and ended up with a diagnosis of arrhythmogenic cardiomyopathy, mostly of the left predominant type. The aim of this case presentation is to shed light upon a possible link between myocarditis, a desmoplakin (DSP) gene variant, and ARVC by describing a case of male monozygotic twins who presented with symptoms and signs of myocarditis at 17 and 18 years of age, respectively. One of them also had a recurrent episode of myocarditis. The twins and their family were extensively examined including electrocardiograms (ECG), biochemistry, multimodal cardiac imaging, myocardial biopsy, genetic analysis, repeated cardiac magnetic resonance (CMR) and echocardiography over time. Both twins presented with chest pain, ECG with slight ST-T elevation, and increased troponin T levels. CMR demonstrated an affected left ventricle with comprehensive inflammatory, subepicardial changes consistent with myocarditis. The right ventricle did not appear to have any abnormalities. Genotype analysis revealed a nonsense heterozygous variant in the desmoplakin (DSP) gene [NM_004415.2:c.2521_2522del (p.Gln841Aspfs*9)] that is considered likely pathogenic and presumably ARVC related. There was no previous family history of heart disease. There might be a common pathophysiology of ARVC, associated with desmosomal dysfunction, and myocarditis. In our case, both twins have an affected left ventricle without any right ventricular involvement, and they are carriers of a novel DSP variant that is likely associated with ARVC. The extensive inflammation of the LV that was apparent in the CMR may or may not be the primary event of ARVC. Nevertheless, our data suggest that irrespective of a possible link here to ARVC, genetic testing for arrhythmogenic cardiomyopathy might be advisable for patients with recurrent myocarditis associated with a family history of myocarditis.
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| 28. |
- Kälvegren, Hanna, et al.
(författare)
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Release of matrix metalloproteinases-1 and-2, but not-9, from activated platelets measured by enzyme-linked immunosorbent assay
- 2011
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Ingår i: Platelets. - : Informa Healthcare. - 0953-7104 .- 1369-1635. ; 22:8, s. 572-578
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Tidskriftsartikel (refereegranskat)abstract
- Matrix metalloproteinases (MMPs), in particular MMP-9, have been introduced as novel biomarkers in coronary artery disease. Activated platelets are considered to be a major source of the highly elevated levels of MMPs that are detected in serum compared to plasma. The aim of this study was to clarify if activated platelets release MMPs-1, -2 and -9 as measured by enzyme-linked immunosorbent assays (ELISA). Isolated platelets (separated by several procedures) or platelet-rich plasma (PRP) were stimulated by collagen, thrombin or the TLR2 agonist Pam(3)CSK(4). The concentrations of MMPs-1,-2 and -9 in supernatants were determined by ELISA. In addition, a MMP-9 enzyme activity assay was used as well as immunofluorescent staining of MMPs-1,-2 and 9 in platelets. Isolated platelets stimulated by collagen, thrombin or Pam(3)CSK(4) released significant amounts of MMP-1 to the supernatant measured as either pro- or total-MMP-1. However, there was no detectable release of MMP-2 or -9 from isolated platelets. Collagen-stimulated platelets in PRP released MMP-2, but not -9. Before stimulation; platelets were positive for MMPs-1 and -2, but not -9, as assessed by immunofluorescence. Acting as positive controls, neutrophils were found to release significant amounts of MMP-9. Our findings indicate that activated platelets may be a major source of MMP-1 and to a minor extent MMP-2, in peripheral blood. However, in contrast to what has been argued in previous literature, platelets appear to be only negligible contributors to circulating MMP-9.
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| 29. |
- Magnusson, Karin, et al.
(författare)
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An imidazole functionalized pentameric thiophene displays different staining patterns in normal and malignant cells
- 2015
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Molecular tools for fluorescent imaging of cells and their components are vital for understanding the function and activity of cells. Here, we report an imidazole functionalized pentameric oligothiophene, p-HTIm, that can be utilized for fluorescent imaging of cells. p-HTIm fluorescence in normal cells appeared in a peripheral punctate pattern partially co-localized with lysosomes, whereas a one-sided perinuclear Golgi associated localization of the dye was observed in malignant cells. The uptake of p-HTIm was temperature dependent and the intracellular target was reached within 1 h after staining. The ability of p-HTIm to stain cells was reduced when the imidazole side chain was chemically altered, verifying that specific imidazole side-chain functionalities are necessary for achieving the observed cellular staining. Our findings confirm that properly functionalized oligothiophenes can be utilized as fluorescent tools for vital staining of cells and that the selectivity towards distinct intracellular targets are highly dependent on the side-chain functionalities along the conjugated thiophene backbone.
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| 30. |
- Magnusson, Karin, et al.
(författare)
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Differential vital staining of normal fibroblasts and melanoma cells by an anionic conjugated polyelectrolyte
- 2015
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Ingår i: Cytometry Part A. - : Wiley: 12 months. - 1552-4922 .- 1552-4930. ; 87:3, s. 262-272
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Tidskriftsartikel (refereegranskat)abstract
- Molecular probes for imaging of live cells are of great interest for studying biological and pathological processes. The anionic luminescent conjugated polythiophene (LCP) polythiophene acetic acid (PTAA), has previously been used for vital staining of cultured fibroblasts as well as transformed cells with results indicating differential staining due to cell phenotype. Herein, we investigated the behavior of PTAA in two normal and five transformed cells lines. PTAA fluorescence in normal cells appeared in a peripheral punctated pattern whereas the probe was more concentrated in a one-sided perinuclear localization in the five transformed cell lines. In fibroblasts, PTAA fluorescence was initially associated with fibronectin and after 24 h partially localized to lysosomes. The uptake and intracellular target in malignant melanoma cells was more ambiguous and the intracellular target of PTAA in melanoma cells is still elusive. PTAA was well tolerated by both fibroblasts and melanoma cells, and microscopic analysis as well as viability assays showed no signs of negative influence on growth. Stained cells maintained their proliferation rate for at least 12 generations. Although the probe itself was nontoxic, photoinduced cellular toxicity was observed in both cell lines upon irradiation directly after staining. However, no cytotoxicity was detected when the cells were irradiated 24 h after staining, indicating that the photoinduced toxicity is dependent on the cellular location of the probe. Overall, these studies certified PTAA as a useful agent for vital staining of cells, and that PTAA can potentially be used to study cancer-related biological and pathological processes.
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| 31. |
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| 32. |
- Pascual, Didac, et al.
(författare)
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The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study
- 2021
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Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 50:2, s. 375-392
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Forskningsöversikt (refereegranskat)abstract
- Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.
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| 33. |
- Persson, Anna, et al.
(författare)
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Heart Rate Variability for Classification of Alert Versus Sleep Deprived Drivers in Real Road Driving Conditions
- 2021
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - : IEEE. - 1524-9050 .- 1558-0016. ; 22:6, s. 3316-3325
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Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness is a contributing factor in many road fatalities. A long-standing goal in driver state research has therefore been to develop a robust sleepiness detection system. It has been suggested that various heart rate variability (HRV) metrics can be used for driver sleepiness classification. However, since heart rate is modulated not only by sleepiness but also by several other time-varying intra-individual factors such as posture, distress, boredom and relaxation, it is relevant to highlight not only the possibilities but also the difficulties involved in HRV-based driver sleepiness classification. This paper investigates the reliability of HRV as a standalone feature for driver sleepiness detection in a realistic setting. Data from three real-road driving studies were used, including 86 drivers in both alert and sleep-deprived conditions. Subjective ratings based on the Karolinska sleepiness scale (KSS) were used as ground truth when training four binary classifiers (k-nearest neighbours, support vector machine, AdaBoost, and random forest). The best performance was achieved with the random forest classifier with an accuracy of 85%. However, the accuracy dropped to 64% for three-class classification and to 44% for subject-independent, leave-one-participant-out classification. The worst results were obtained in the severely sleepy class. The results show that in realistic driving conditions, subject-independent sleepiness classification based on HRV is poor. The conclusion is that more work is needed to control for the many confounding factors that also influence HRV before it can be used as input to a driver sleepiness detection system.
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| 34. |
- Persson, Anna, et al.
(författare)
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Heart Rate Variability for Driver Sleepiness Classification in Real Road Driving Conditions
- 2019
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Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. - : IEEE. - 9781538613115 - 9781538613122 ; , s. 6537-6540
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Konferensbidrag (refereegranskat)abstract
- Approximately 20-30% of all road fatalities are related to driver sleepiness. A long-lasting goal in driver state research has therefore been to develop a robust sleepiness detection system. Since the alertness level is reflected in autonomous nervous system activity, it has been suggested that various heart rate variability (HRV) metrics can be used as features for driver sleepiness classification. Since the heart rate is modulated by many different factors, and not just by sleepiness, it is relevant to question the high driver sleepiness classification accuracies that have occasionally been presented in the literature. The main objective of this paper is thus to test how well a sleepiness classification system based on HRV features really is. A unique data set with 86 drivers, obtained while driving on real roads in real traffic, both in alert and sleep deprived conditions, was used to train and test a support vector machine (SVM) classifier. Subjective ratings based on the Karolinska sleepiness scale (KSS) was used as ground truth to divide the data into three classes (alert, somewhat sleepy and severely sleepy). Even though nearly all the 24 investigated HRV metrics showed significant differences between sleepiness levels, the SVM results only reached a mean accuracy of 61 %, with the worst results originating from the severely sleepy cases. In summary, the high classification performance that may arise in studies with high experimental control could not be replicated under realistic driving conditions. Future works should focus on how various confounding factors should be accounted for when using HRV based metrics as input to a driver sleepiness detection system.
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| 35. |
- Ridefelt, Hanna, et al.
(författare)
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Statistic-empirical modelling of mountain permafrost distribution in the Abisko region, sub-Arctic northern Sweden
- 2008
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Ingår i: Norsk Geografisk Tidsskrift. - : Informa UK Limited. - 0029-1951 .- 1502-5292. ; 62:4, s. 278-289
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Tidskriftsartikel (refereegranskat)abstract
- The mountain permafrost distribution in the Abisko region in northern Sweden has been assessed using a combination of empirical and statistical analysis. The empirical data was obtained using the bottom temperature of snow cover (BTS) method, supported by continuous ground temperature measurements. The statistical analysis was based on 148 data points in total and used logistic regression to model the probability of permafrost occurrence. Further, Geographically Weighted Regression (GWR) was introduced as an exploratory tool for detecting non-stationarity in the relationships between permafrost and the independent variables models and showed to be a useful tool in the statistical analysis. As a result of the GWR analysis the region was divided into two subregions. The models show probabilities > 0.8 for permafrost at elevations above 1300 m a.s.l. in the western part of the region. In the eastern part, the probabilities are likely to be influenced by the potential incoming shortwave summer radiation, indicating a probability > 0.8 above 850 m a.s.l. on the north-east and east-facing slopes, above 1000 m on the west-facing slopes and above 1100 m a.s.l. on the south-facing slopes. Permafrost conditions throughout the region were found to be marginal and sensitive to current warming trends.
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| 36. |
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| 37. |
- Svensson, Christina, et al.
(författare)
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Affected Microcirculation and Vascular Hemodynamics in Takayasu Arteritis
- 2022
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Takayasu arteritis (TAK) is a rare inflammatory disease affecting aorta and its major branches. Ultrasound (US) can detect inflammatory features in the arterial wall, but less is known regarding skin microcirculation and vascular hemodynamics. The aim was to study if assessment of these variables could add valuable information regarding vascular affection in TAK.Methods: 17 patients diagnosed with TAK and 17 age- and sex-matched healthy controls were included. Microcirculatory peak oxygen saturation (OxyP) in the skin after induced ischemia was evaluated with laser Doppler flowmetry/diffuse reflectance spectroscopy. Cerebrovascular reserve capacity (CVR) in the brain was assessed with transcranial Doppler (TCD). Pulse waves were recorded in the radial artery by the aid of applanation tonometry, for calculation of central augmentation index (AIx75). Intima-media thickness (IMT) and stenosis/occlusions were evaluated using US in carotid and central arteries.Results: Reduced OxyP (79 +/- 8% vs. 87 +/- 4%, p < 0.001) was seen in patients with TAK regardless of significant arterial stenosis/occlusion or not. Increased AIx75 (22.3 +/- 13.6 vs. 9.2 +/- 16.3, p = 0.01) was seen in TAK patients without significant stenosis/occlusions. No differences were found in CVR, regardless of proximal stenosis. However, signs of a more high-resistance flow profile were seen in arteria cerebri media.Conclusion: Regardless of arterial stenosis or not, impaired microcirculation of the skin and preserved CVR in the brain were found in subjects with TAK. Signs of increased arterial stiffness in the brain and central arteries were observed. The value of these findings for prediction of future cardiovascular events needs to be clarified in further studies.
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| 38. |
- Svensson, Christina, et al.
(författare)
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Impaired Microcirculation and Vascular Hemodynamics in Relation to Macrocirculation in Patients With Systemic Lupus Erythematosus
- 2021
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Ingår i: Frontiers in Medicine. - : Frontiers Media SA. - 2296-858X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Systemic lupus erythematosus (SLE) is associated with premature cardiovascular disease (CVD) and mortality, unexplained by traditional risk factors. Impairment of microcirculation and vascular hemodynamics may represent early signs of vascular affection. We hypothesized that studies of microcirculation and pulse waves may provide additional information, compared to ultrasound (US) alone, for the detection of early vascular disease in SLE.Methods: Sixty well-characterized SLE-patients (52 women, eight men; mean age 43.21 +/- 1.3 years) characterized by lupus nephritis (LN; n = 20), antiphospholipid syndrome (APS; n = 20) or skin and joint involvement (n = 20) and 60 healthy controls were included. Microcirculatory peak oxygen saturation (OxyP) was evaluated using a novel combined laser Doppler flowmetry/diffuse reflectance spectroscopy method. Pulse waves were recorded in the radial artery by the aid of applanation tonometry in order to calculate central augmentation index (AIx75). Intima-media thickness (IMT) and plaque occurrence were evaluated using high frequency US, in carotid and central arteries.Results: Lower OxyP (84 +/- 8 vs. 87 +/- 5 %, p = 0.01) and higher AIx75 (17.3 +/- 13.9 vs. 10.0 +/- 14.2 %, p = 0.005) were seen in the SLE cohort. OxyP was inversely correlated with IMT in internal carotid artery (ICA), (R = -0.32, p = 0.01). AIx75 correlated with IMT in common carotid artery (CCA), (R = 0.36, p = 0.005), common femoral artery (CFA), (R = 0.43, p = 0.001), and ICA (R = 0.27, p = 0.04). AIx75 correlated negatively with OxyP (R = -0.29, p = 0.02). SLE-patients with plaque had lower OxyP values (80 +/- 8 vs. 85 +/- 7 %, p < 0.001) and higher AIx75 (23.0 +/- 11.6 vs. 15.5 +/- 14.2 %, p < 0.001) compared to those without plaque.Conclusion: Impaired microcirculation and vessel hemodynamics were observed in SLE. These methods correlated with IMT and plaque occurrence. The importance of early macro- and micro-circulatory vascular affection for increased risk of CVD in SLE will be followed-up in future studies.
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| 39. |
- Swahn, Eva, 1949-, et al.
(författare)
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Prevalence and determinants of dilated ascending aorta in a Swedish population: a case-control study
- 2023
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Ingår i: European Heart Journal Open. - : Oxford University Press. - 2752-4191. ; 3:5
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Dilation of the ascending aorta (AA) is often asymptomatic until a life-threatening dissection or rupture occurs. An overall increase in the use of thoracic imaging has enabled early and sometimes incidental identification of AA dilation. Still, the prevalence and determinants of AA dilation remain to be clarified. The aim was to identify and characterize persons with AA dilation in a middle-aged Swedish population.Methods and results: We used the Swedish CardioPulmonary BioImage Study Linköping (n = 5058, age 50-65 years) to identify cases with AA diameter ≥ 40 mm on coronary computed tomography angiography (CCTA) or chest computed tomography. Age- and gender-matched individuals with AA diameter < 40 mm served as controls. Echocardiography, blood pressure (BP) measurements (office and home), pulse wave velocity (PWV), coronary artery calcification (CAC), CCTA-detected coronary atherosclerosis, and carotid ultrasound were used to characterize these subjects. We identified 70 cases (mean AA diameter 44 mm, 77% men) and matched these to 146 controls (mean AA diameter 34 mm). Bicuspid aortic valve and aortic valve dysfunction were more common in cases than in controls (8% vs. 0% and 39% vs. 11%, respectively). Both office and home BP levels were significantly higher among cases. Also, high PWV (>10 m/s) levels were more common in cases (33% vs. 17%). Neither CAC scores nor prevalence or burden of atherosclerosis in coronary and carotid arteries differed between groups.Conclusion: The prevalence of dilated AA was 1.4% and showed positive associations with male gender, aortic valve pathology, and diastolic BP, though not with subclinical atherosclerosis.
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| 40. |
- Witwit, Wisam, et al.
(författare)
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Young soccer players have significantly more spinal changes on MRI compared to non-athletes.
- 2020
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Ingår i: Translational Sports Medicine. - : Hindawi Limited. - 2573-8488. ; 3:4, s. 288-295
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Evidence-based facts regarding spinal abnormalities and back pain in young athletes are needed in order to be able to adapt rehabilitation programs and preventive measures accordingly. The aim of this study was therefore to identify MRI changes in the thoracolumbar spine and the lifetime prevalence of back pain in young football players compared to non-athletes. Methods Young elite football players (n = 27) and non-athletes (n = 26) completed MRI examinations of the thoracolumbar spine. MRI images were evaluated for disk signal, height, bulging, herniation, Schmorl's nodes, spondylolisthesis, and vertebral wedging. All participants answered questionnaires regarding training hours and back pain. Results Disk degenerative changes were more commonly displayed by 89% of the football players compared to 54% of the controls (P = .006). Schmorl's nodes (22%), disk herniation (30%), and reduced disk height (37%) were more prevalent in football players compared to controls (0%) (P = .023 and P = .001, respectively). The lifetime prevalence of back pain was reported by 52% of football players and 44% of controls, a difference that was not statistically significant. Conclusion Young male football (soccer) players have more degenerative disk changes compared to non-athletes. Both groups displayed high lifetime prevalence of back pain.
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| 41. |
- Yang, Zhenlin, et al.
(författare)
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How can meteorological observations and microclimate simulations improve understanding of 1913-2010 climate change around Abisko, Swedish Lapland?
- 2012
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Ingår i: Meteorological Applications. - : Wiley. - 1350-4827. ; 19:4, s. 454-463
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analysis of 2 years' hourly microclimatic (mainly surface air temperature) data recently acquired from locations widely dispersed over 700 km2 in the Abisko catchment encompassing Lake Tornetrask in Swedish Lapland is presented in this study. This project is designed to explore the effects of microclimatic variability, past and future climate change (1913-2100) on regional vegetation and land-use changes, at an unique Arctic ecological and climate monitoring site, to aid adaptation of stakeholders to future climate change. Dominant altitudinal lapse rate and radiation effects during summer are revealed in detailed analysis of spatial variations in temperature between the different sites, which become largely negated during winter when cold-air ponding is much more significant. Moreover, near-shore temperatures are moderated significantly by Lake Tornetrask during the spring lake-ice melt season. The extent to which synoptic meteorological conditions affect these factors is explored. Examples of gridded temperature maps for the Abisko region are also presented, produced using a downscaling model based on the temperature data, which have numerous ecological and other applications. The long-term Abisko Scientific Research Station meteorological record, which spans almost a century from 1913 to present is also explored, for evidence of climate change, to set the temperature logger data in a long-term climate context. Exploratory analysis of the possible influence of future regional climate change on ecological/vegetation zones is also briefly discussed. Copyright (C) 2011 Royal Meteorological Society
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