| 1. |
- Andersson, Thord, et al.
(författare)
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Consistent intensity inhomogeneity correction in water-fat MRI
- 2015
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley-Blackwell. - 1053-1807 .- 1522-2586. ; 42:2
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To quantitatively and qualitatively evaluate the water-signal performance of the consistent intensity inhomogeneity correction (CIIC) method to correct for intensity inhomogeneitiesMETHODS: Water-fat volumes were acquired using 1.5 Tesla (T) and 3.0T symmetrically sampled 2-point Dixon three-dimensional MRI. Two datasets: (i) 10 muscle tissue regions of interest (ROIs) from 10 subjects acquired with both 1.5T and 3.0T whole-body MRI. (ii) Seven liver tissue ROIs from 36 patients imaged using 1.5T MRI at six time points after Gd-EOB-DTPA injection. The performance of CIIC was evaluated quantitatively by analyzing its impact on the dispersion and bias of the water image ROI intensities, and qualitatively using side-by-side image comparisons.RESULTS: CIIC significantly ( P1.5T≤2.3×10-4,P3.0T≤1.0×10-6) decreased the nonphysiological intensity variance while preserving the average intensity levels. The side-by-side comparisons showed improved intensity consistency ( Pint≤10-6) while not introducing artifacts ( Part=0.024) nor changed appearances ( Papp≤10-6).CONCLUSION: CIIC improves the spatiotemporal intensity consistency in regions of a homogenous tissue type.
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| 2. |
- Bridel, Claire, et al.
(författare)
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Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology : A Systematic Review and Meta-analysis
- 2019
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Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149 .- 2168-6157. ; 76:9, s. 1035-1048
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Forskningsöversikt (refereegranskat)abstract
- Importance Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.Objectives To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.Data Sources PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.Study Selection Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.Data Extraction and Synthesis Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.Main Outcome and Measure The cNfL levels adjusted for age and sex across diagnoses.Results Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.Conclusions and Relevance These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.
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| 3. |
- Eriksson, Mikael, 1977-
(författare)
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The complex internationalization process unfolded : The case of Atlas Copco’s entry into the Chinese mid-market
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite its contemporary relevance, we still have limited empirical knowledge about the forces underlying complex internationalization processes as when multinational corporations (MNCs) seek to enter new growing markets. Based on a real-time process study comprising ninety interviews and two hundred hours of observation made between 2009 and 2012, Atlas Copco’s entry into the Chinese mid-market was investigated. The intra-organizational analysis showed that three inter-related processes were underlying Atlas’ market entry and the results suggest that multiple interrelated motors may drive many contemporary internationalization processes. The processes identified are a sequential strategy process, an evolutionary process which shows that routines changed, and a political process. A somewhat surprising finding is that the main driver of internationalization according to received theory, the firm’s accumulated experiences, not only can drive internationalization, but may also hamper MNC managers’ possibilities to enter many of today’s new and growing markets. The findings add to our knowledge of the internationalization process in an increasingly complex international business setting, and especially highlight the need to distinguish between the sequential strategy process – more in line with received theory – and the other processes, in order to get a more full-fledged picture of what internationalization in large MNCs is all about.
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| 4. |
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| 5. |
- Forsgren, Lilian, 1990, et al.
(författare)
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Composites with surface-grafted cellulose nanocrystals (CNC)
- 2019
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 54:4, s. 3009-3022
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Tidskriftsartikel (refereegranskat)abstract
- Hydroxyazetidinium salts were used to surface-modify cellulose nanocrystals (CNC) by grafting the salts onto the sulphate ester groups on the CNC surfaces. The grafting was confirmed by ζ-potential measurements and by the thermal degradation behaviour of the modified CNC. The thermal stability (onset of degradation) of the CNC was improved by the surface modification (almost 100 °C). Composites containing surface-modified or unmodified CNC (0.1, 1.0 and 10 wt%) with an ethylene-based copolymer as matrix were produced by compression moulding. The thermal stability of the composites was not, however, markedly improved by the surface grafting onto the CNC. It is suggested that this is due to a degrafting mechanism, associated with the alkaline character of the system, taking place at high temperatures. Model experiments indicated, however, that this did not occur at the conditions under which the composites were produced. Furthermore, in the case of a reference based on pH-neutralised polymeric system and modified CNC, an upward shift in the onset of thermal degradation of the composite was observed. The addition of the CNC to the polymer matrix had a strong influence of the mechanical performance. For example, the tensile modulus increased approximately three times for some systems when adding 10 wt% CNC. The surface grafting of the hydroxyazetidinium salts appeared mainly to affect, in a positive sense, the yield behaviour and ductility of the composites. The results of the mechanical testing are discussed in terms of interactions between the grafted units and the matrix material and between the grafted groups.
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| 6. |
- Forsgren, Lilian, 1990, et al.
(författare)
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Injection Molding and Appearance of Cellulose-Reinforced Composites
- 2019
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Ingår i: Polymer Engineering and Science. - : John Wiley and Sons Inc.. - 0032-3888 .- 1548-2634. ; 60:1, s. 5-12
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Tidskriftsartikel (refereegranskat)abstract
- Composite materials based on an ethylene-acrylic acid (EAA) copolymer and 20 wt% cellulose fibers were compounded by two runs in a twin-screw extruder. The composite material with cellulose fibers (CF) and a reference of unfilled EAA were injection molded into plaques using three different temperature profiles with end zone temperatures of 170°C, 200°C, and 230°C. The injection molded samples were then characterized in terms of their mechanical properties, thermal properties, appearance (color and gloss), and surface topography. The higher processing temperatures resulted in a clear discoloration of the composites, but there was no deterioration in the mechanical performance. The addition of cellulose typically gave a tensile modulus three times higher than that of the unfilled EAA, but the strength and strain at rupture were reduced when fibers were added. The processing temperature had no significant influence on the mechanical properties of the composites. Gloss measurements revealed negligible differences between the samples molded at the different melt temperatures but the surface smoothness was somewhat higher when the melt temperature was increased. In general, addition of the cellulose to the EAA reduced the gloss level and the surface smoothness.
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| 7. |
- Forsgren, Mikael, et al.
(författare)
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Comparing hepatic 2D and 3D magnetic resonance elastography methods in a clinical setting – Initial experiences
- 2015
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Ingår i: European Journal of Radiology Open. - : Elsevier. - 2352-0477. ; 2, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- PurposeContinuous monitoring of liver fibrosis progression in patients is not feasible with the current diagnostic golden standard (needle biopsy). Recently, magnetic resonance elastography (MRE) has emerged as a promising method for such continuous monitoring. Since there are different MRE methods that could be used in a clinical setting there is a need to investigate whether measurements produced by these MRE methods are comparable. Hence, the purpose of this pilot study was to evaluate whether the measurements of the viscoelastic properties produced by 2D (stiffness) and 3D (elasticity and ‘Gabs,Elastic’) MRE are comparable.Materials and methodsSeven patients with diffuse or suspect diffuse liver disease were examined in the same day with the two MRE methods. 2D MRE was performed using an acoustic passive transducer, with a 1.5 T GE 450 W MR system. 3D MRE was performed using an electromagnetic active transducer, with a 1.5 T Philips Achieva MR system. Finally, mean viscoelastic values were extracted from the same anatomical region for both methods by an experienced radiologist.ResultsStiffness correlated well with the elasticity, R2 = 0.96 (P < 0.001; slope = 1.08, intercept = 0.61 kPa), as well as with ‘Gabs,Elastic’ R2 = 0.96 (P < 0.001; slope = 0.95, intercept = 0.28 kPa).ConclusionThis pilot study shows that different MRE methods can produce comparable measurements of the viscoelastic properties of the liver. The existence of such comparable measurements is important, both from a clinical as well as a research perspective, since it allows for equipment-independent monitoring of disease progression.
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| 8. |
- Forsgren, Mikael, et al.
(författare)
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Model-inferred mechanisms of liver function from magnetic resonance imaging data : Validation and variation across a clinically relevant cohort
- 2019
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Ingår i: PloS Computational Biology. - San Francisco, CA, United States : Public Library of Science. - 1553-734X .- 1553-7358. ; 15:6
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Tidskriftsartikel (refereegranskat)abstract
- Estimation of liver function is important to monitor progression of chronic liver disease (CLD). A promising method is magnetic resonance imaging (MRI) combined with gadoxetate, a liver-specific contrast agent. For this method, we have previously developed a model for an average healthy human. Herein, we extended this model, by combining it with a patient-specific non-linear mixed-effects modeling framework. We validated the model by recruiting 100 patients with CLD of varying severity and etiologies. The model explained all MRI data and adequately predicted both timepoints saved for validation and gadoxetate concentrations in both plasma and biopsies. The validated model provides a new and deeper look into how the mechanisms of liver function vary across a wide variety of liver diseases. The basic mechanisms remain the same, but increasing fibrosis reduces uptake and increases excretion of gadoxetate. These mechanisms are shared across many liver functions and can now be estimated from standard clinical images.Author summaryBeing able to accurately and reliably estimate liver function is important when monitoring the progression of patients with liver disease, as well as when identifying drug-induced liver injury during drug development. A promising method for quantifying liver function is to use magnetic resonance imaging combined with gadoxetate. Gadoxetate is a liver-specific contrast agent, which is taken up by the hepatocytes and excreted into the bile. We have previously developed a mechanistic model for gadoxetate dynamics using averaged data from healthy volunteers. In this work, we extended our model with a non-linear mixed-effects modeling framework to give patient-specific estimates of the gadoxetate transport-rates. We validated the model by recruiting 100 patients with liver disease, covering a range of severity and etiologies. All patients underwent an MRI-examination and provided both blood and liver biopsies. Our validated model provides a new and deeper look into how the mechanisms of liver function varies across a wide variety of liver diseases. The basic mechanisms remain the same, but increasing fibrosis reduces uptake and increases excretion of gadoxetate.
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| 9. |
- Forsgren, Mikael
(författare)
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The Non-Invasive Liver Biopsy : Determining Hepatic Function in Diffuse and Focal LiverDisease
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The liver is one of the largest organs within the human body and it handles many vital tasks such as nutrient processing, toxin removal, and synthesis of important proteins. The number of people suffering from chronic liver disease is on the rise, likely due to the present ‘western’ lifestyle. As disease develops in the liver there are pathophysiological manifestations within the liver parenchyma that are both common and important to monitor. These manifestations include inflammation, fatty infiltration (steatosis), excessive scar tissue formation (fibrosis and cirrhosis), and iron loading. Importantly, as the disease progresses there is concurrent loss of liver function. Furthermore, postoperative liver function insufficiency is an important concern when planning surgical treatment of the liver, because it is associated with both morbidity and mortality. Liver function can also be hampered due to drug-induced injuries, an important aspect to consider in drug-development.Currently, an invasive liver needle biopsy is required to determine the aetiology and to stage or grade the pathophysiological manifestations. There are important limitations with the biopsy, which include, risk of serious complications, mortality, morbidity, inter- and intra-observer variability, sampling error, and sampling variability. Cleary, it would be beneficial to be able investigate the pathophysiological manifestations accurately, non-invasively, and on regional level.Current available laboratory liver function blood panels are typically insufficient and often only indicate damage at a late stage. Thus, it would be beneficial to have access to biomarkers that are both sensitive and responds to early changes in liver function in both clinical settings and for the pharmaceutical industry and regulatory agencies.The main aim of this thesis was to develop and evaluate methods that can be used for a ‘non-invasive liver biopsy’ using magnetic resonance (MR). We also aimed to develop sensitive methods for measure liver function based on gadoxetate-enhanced MR imaging (MRI).The presented work is primarily based on a prospective study on c. 100 patients suffering from chronic liver disease of varying aetiologies recruited due to elevated liver enzyme levels, without clear signs of decompensated cirrhosis. Our results show that the commonly used liver fat cut-off for diagnosing steatosis should be lowered from 5% to 3% when using MR proton-density fat fraction (PDFF). We also show that MR elastography (MRE) is superior in staging fibrosis.Finally we presented a framework for quantifying liver function based on gadoxetate-enhanced MRI. The method is based on clinical images and a clinical approved contrast agent (gadoxetate). The framework consists of; state-of the-art image reconstruction and correction methods, a mathematical model, and a precise model parametrization method. The model was developed and validated on healthy subjects. Thereafter the model was found applicable on the chronic liver disease cohort as well as validated using gadoxetate levels in biopsy samples and blood samples. The liver function parameters correlated with clinical markers for liver function and liver fibrosis (used as a surrogate marker for liver function).In summary, it should be possible to perform a non-invasive liver biopsy using: MRI-PDFF for liver fat and iron loading, MRE for liver fibrosis and possibly also inflammation, and measure liver function using the presented framework for analysing gadoxetate-enhanced MRI. With the exception of an MREtransducer no additional hardware is required on the MR scanner. The liver function method is likely to be useful both in a clinical setting and in pharmaceutical trials.
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| 10. |
- Karageorgis, Anastassia, et al.
(författare)
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A multi-center preclinical study of gadoxetate DCE-MRI in rats as a biomarker of drug induced inhibition of liver transporter function
- 2018
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Drug-induced liver injury (Dili) is a leading cause of acute liver failure and transplantation. Dili can be the result of impaired hepatobiliary transporters, with altered bile formation, flow, and subsequent cholestasis. We used gadoxetate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), combined with pharmacokinetic modelling, to measure hepatobiliary transporter function in vivo in rats. The sensitivity and robustness of the method was tested by evaluating the effect of a clinical dose of the antibiotic rifampicin in four different preclinical imaging centers. The mean gadoxetate uptake rate constant for the vehicle groups at all centers was 39.3 +/- 3.4 s -1 (n = 23) and 11.7 +/- 1.3 s -1 (n = 20) for the rifampicin groups. The mean gadoxetate efflux rate constant for the vehicle groups was 1.53 +/- 0.08 s -1 (n = 23) and for the rifampicin treated groups was 0.94 +/- 0.08 s -1 (n = 20). Both the uptake and excretion transporters of gadoxetate were statistically significantly inhibited by the clinical dose of rifampicin at all centers and the size of this treatment group effect was consistent across the centers. Gadoxetate is a clinically approved MRI contrast agent, so this method is readily transferable to the clinic. Conclusion: Rate constants of
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| 11. |
- Karlsson, Markus, et al.
(författare)
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Diffuse Liver Disease: Measurements of Liver Trace Metal Concentrations and R2* Relaxation Rates
- 2016
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Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer. - 0968-5243 .- 1352-8661. ; 29:1, s. S395-S395
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionOver the past decade, several methods for measuring of liver iron content (LIC) non-invasively with MRI have been developed and verified. The most promising methods uses relaxometry, measuring either R2- or R2* relaxation rate in the liver1,2. For instance, several studies have shown that there seems to be a linear relationship between R2* and LIC1. However, few of these studies have measured the liver content of other metals, which could also affect the relaxation rates. The goal of this study was to investigate if any trace metals, other than iron could affect the R2* relaxation rate in liver tissue in a patients with diffuse liver disease.Subjects and methods75 patients with suspected diffuse liver disease underwent an MRI examination followed by a liver biopsy the same day. The R2* relaxation rate of the water protons in the liver was measured using an axial 3D multi-slice fat-saturated multi-echo turbo field echo sequence (TE=4.60/9.20/13.80/18.40/23.00ms). Regions of interest (ROI) were drawn and R2* was estimated by fitting the mean signal intensity from the ROIs to a mono-exponential decay model. The biopsies were freeze dried and the concentrations of iron, manganese, copper, cobalt and gadolinium were measured using Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SFMS). A multiple linear regression analysis was applied to determine which of the measured metals significantly affected the relaxation rate.ResultsA linear regression with the LIC and R2* showed a reasonable fit (Figure 1). The multiple linear regression analysis (Table 1) showed that iron as well as manganese had a significant affect on R2*. Unlike iron however, the regression coefficient of manganese was negative, meaning that an increasing manganese concentration gave a shorter R2* relaxation rate. The same trend can be seen when plotting the manganese concentration against R2* (Figure 2).
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| 12. |
- Karlsson, Markus, et al.
(författare)
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Increased bile excretion of Gd-EOB-DTPA in diffuse liver disease : mechanistic modeling of qDCE-MRI in patients with severe fibro-sis
- 2016
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Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer. - 0968-5243 .- 1352-8661. ; 29:1, s. S272-S273
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionOver the past decades, several different non-invasive methods for staging hepatic fibrosis have been proposed. One such method is dynamic contrast enhanced MRI (DCE-MRI) using the contrast agent (CA) Gd-EOB-DTPA. Gd-EOB-DTPA is liver specific, which means that it is taken up specifically by the hepatocytes via the OATP3B1/B3 transporters and excreted into the bile via the MRP2 transporter. Several studies have shown that DCE-MRI and Gd-EOBDTPA can separate patients with advanced (F3-F4) from mild (F0-F2) hepatic fibrosis by measuring the signal intensity, where patients with advanced fibrosis have a lower signal intensity than the mild fibrosis cases.1 However, none of the studies up to date have been able to differentiate if the reduced signal intensity in the liver is because of an decreased uptake of CA or an increased excretion. Analyzing the DCE-MRI data with mechanistic mathematical modelling has the possibility of investigating such a differentiation.Subjects and methods88 patients with diffuse liver disease were examined using DCE-MRI (1.5 T Philips Achieva, two-point Dixon, TR=6.5 ms, TE=2.3/4.6 ms, FA=13) after a bolus injection of Gd-EOB-DTPA, followed by a liver biopsy. Regions of interest were placed within the liver, spleen and veins and a whole-body mechanistic pharmacokinetic model2 was fitted to the data. The fitted parameters in the model correspond to the rate of CA transport between different compartments, e.g. hepatocytes, blood plasma, and bile (Fig. 1).ResultsAs can be seen in Fig. 2, the parameter corresponding to the transport of CA from the blood plasma to the hepatocytes, kph, is lower for patients with advanced fibrosis (p=0.01). Fig. 3 shows that the parameter corresponding to the CA excretion into the bile, khb, is higher for patients with advanced fibrosis (p<0.01).Discussion/ConclusionThis work shows that the decreased signal intensity in DCE-MRI images in patients with advanced fibrosis depends on both a decreased uptake of CA in the hepatocytes and an increased excretion into the bile. Similar results have also been observed in a rat study3. In that study, rats with induced cirrhosis had a higher MRP2-activity than the healthy control rats.References1Norén et al: Eur. Radiol, 23(1), 174-181, 2013.2Forsgren et al: PloS One, 9(4): e95700, 2014.3Tsuda & Matsui: Radiol, 256(3): 767-773, 2010.
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| 13. |
- Karlsson, Markus, et al.
(författare)
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Liver R2*is affected by both iron and fat: A dual biopsy-validated study of chronic liver disease
- 2019
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Ingår i: Journal of Magnetic Resonance Imaging. - : WILEY. - 1053-1807 .- 1522-2586. ; 50:1, s. 325-333
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Tidskriftsartikel (refereegranskat)abstract
- Background Liver iron content (LIC) in chronic liver disease (CLD) is currently determined by performing an invasive liver biopsy. MRI using R2* relaxometry is a noninvasive alternative for estimating LIC. Fat accumulation in the liver, or proton density fat fraction (PDFF), may be a possible confounder of R2* measurements. Previous studies of the effect of PDFF on R2* have not used quantitative LIC measurement. Purpose To assess the associations between R2*, LIC, PDFF, and liver histology in patients with suspected CLD. Study Type Prospective. Population Eighty-one patients with suspected CLD. Field Strength/Sequence 1.5 T. Multiecho turbo field echo to quantify R2*. PRESS MRS to quantify PDFF. Assessment Each patient underwent an MR examination, followed by two needle biopsies immediately following the MR examination. The first biopsy was used for conventional histological assessment of LIC, whereas the second biopsy was used to quantitatively measure LIC using mass spectrometry. R2* was correlated with both LIC and PDFF. A correction for the influence of fat on R2* was calculated. Statistical Tests Pearson correlation, linear regression, and area under the receiver operating curve. Results There was a positive linear correlation between R2* and PDFF (R = 0.69), after removing data from patients with elevated iron levels, as defined by LIC. R2*, corrected for PDFF, was the best method for identifying patients with elevated iron levels, with a correlation of R = 0.87 and a sensitivity and specificity of 87.5% and 98.6%, respectively. Data Conclusion PDFF increases R2*. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:325-333.
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| 14. |
- Karlsson, Mikael, 1978, et al.
(författare)
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Recovery of titanium dioxide and other pigments from waste paint by pyrolysis
- 2015
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Ingår i: Journal of Coatings Technology Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 1935-3804. ; 12:6, s. 1111-1122
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a model paint containing several types of inorganic pigments was pyrolyzed in a microwave-heated unit. The goal of the pyrolysis process was to recover and recycle the inorganic components in the paint, most importantly titanium dioxide (TiO2). The solid residue remaining after pyrolysis was further heat treated in air to remove most of the char in the TiO2-containing product. The recovered TiO2-containing product was used in two types of paint formulation as a replacement for virgin pigments. The properties of the paints containing recycled TiO2 pigment and extenders were evaluated and compared with a standard paint formulation containing only virgin TiO2 pigment and virgin extenders. A reduction in paint whiteness was observed but the opacity, gloss, and durability were nearly equivalent to that of the standard paint. Another consequence of using recycled pigments was that the recycled mix of TiO2 pigments and extenders was harder to disperse in the paint than the mix based on virgin materials, thus giving the painted surface a somewhat rough texture. The recycled material has shown promising results as a pigment/extender but further work is needed to optimize the recycled product to meet whiteness and dispersion requirements for incorporation in paint formulations on an industrial scale.
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| 15. |
- Lundberg, Peter, et al.
(författare)
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Kvantifiering av leversteatos: diagnostisk utvärdering av protonmagnetresonansspektroskopi jämfört med histologiska metoder
- 2016
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Konferensbidrag (refereegranskat)abstract
- BakgrundLeversteatos är den vanligaste manifestationen av leversjukdom i västvärlden. Leverbiopsi med semikvantitativ histologisk gradering är referensmetod vid gradering av leversteatos. Med protonmagnetsresonansspektroskopi (1H-MRS), en metod som föreslagits ersätta leverbiopsi för värdering av steatos, kan leverns innehåll av triglycerider mätas icke-invasivt. Triglyceridinnehåll >5,00 % används ofta som ett diagnostiskt kriterium för leversteatos vid undersökning med 1H-MRS. Syftet med studien var att jämföra 1H-MRS med semikvantitativ histologisk steatosgradering och kvantitativ histologisk steatosmätning.MetodPatienter remitterade för utredning av förhöjda leverenzymer in-kluderades i studien. Samtliga patienter genomgick klinisk undersökning, laboratorieprovtagning samt 1H-MRS direkt följd av leverbiopsi. För konventionell histologisk semikvantitativ gradering av steatos användes kriterierna utarbetade av Brunt och medarbetare. Kvantitativ mätning av fett i biopsierna utfördes genom att med hjälp av stereologisk punkträkning (SPC) mäta andelen av ytan som innehöll fettvakuoler.ResultatI studien inkluderades 94 patienter, varav 37 hade icke-alkoholor-sakad fettleversjukdom (NAFLD), 49 hade andra leversjukdomar och 8 hade normal leverbiopsi. En stark korrelation noterades mel-lan 1H-MRS och SPC (r=0,92, p<0,0001; к=0.82). Korrelationen mellan 1H-MRS och Brunts kriterier (к=0.26) samt mellan SPC och Brunts kriterier (к=0.38) var betydligt sämre. När patologens gradering (Brunts kriterier) användes som referensmetod för diag-nos av leversteatos så hade alla patienter med triglyceridinnehåll >5,00 % mätt med 1H-MRS steatos (specificitet 100 %). Emellertid hade 22 av 69 patienter med triglyceridinnehåll ≤5,00 % också le-versteatos enligt Brunts kriterier (sensitivitet 53 %). Motsvarande siffror när man använde gränsvärdet 3,02 % var sensitivitet 79 % och specificitet 100 %. Vid ytterligare reduktion av gränsvärdet för triglyceridinnehåll till 2,00 % ökade sensitiviteten till 87 % med upprätthållande av hög specificitet (94 %).Slutsats1H-MRS och SPC uppvisade en mycket hög korrelation vid kvantifiering av leversteatos. SPC borde därför föredras framför Brunts kriterier när noggrann histologisk kvantifiering av leversteatos är önskvärd. Många patienter kan ha histologisk leversteatos trots triglyceridinnehåll ≤5,00 % mätt med 1H-MRS. Gränsvärdet för diagnostisering av leversteatos med 1H-MRS bör därför reduceras.
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| 16. |
- Nasr, Patrik, 1987-, et al.
(författare)
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Using a 3% Proton Density Fat Fraction as a Cut-off Value Increases Sensitivity of Detection of Hepatic Steatosis, Based on Results from Histopathology Analysis
- 2017
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Ingår i: Gastroenterology. - : Elsevier. - 0016-5085 .- 1528-0012. ; 153:1, s. 53-
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Tidskriftsartikel (refereegranskat)abstract
- It is possible to estimate hepatic triglyceride content by calculating the proton density fat fraction (PDFF), using proton magnetic resonance spectroscopy (less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS), instead of collecting and analyzing liver biopsies to detect steatosis. However, the current PDFF cut-off value (5%) used to define steatosis by magnetic resonance was derived from studies that did not use histopathology as the reference standard. We performed a prospective study to determine the accuracy of less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF in measurement of steatosis using histopathology analysis as the standard. We collected clinical, serologic, less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF, and liver biopsy data from 94 adult patients with increased levels of liver enzymes (6 months or more) referred to the Department of Gastroenterology and Hepatology at Linköping University Hospital in Sweden from 2007 through 2014. Steatosis was graded using the conventional histopathology method and fat content was quantified in biopsy samples using stereological point counts (SPCs). We correlated less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF findings with SPCs (r = 0.92; P less than.001). less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF results correlated with histopathology results (ρ = 0.87; P less than.001), and SPCs correlated with histopathology results (ρ = 0.88; P less than.001). All 25 subjects with PDFF values of 5.0% or more had steatosis based on histopathology findings (100% specificity for PDFF). However, of 69 subjects with PDFF values below 5.0% (negative result), 22 were determined to have steatosis based on histopathology findings (53% sensitivity for PDFF). Reducing the PDFF cut-off value to 3.0% identified patients with steatosis with 100% specificity and 79% sensitivity; a PDFF cut-off value of 2.0% identified patients with steatosis with 94% specificity and 87% sensitivity. These findings might be used to improve non-invasive detection of steatosis.
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| 17. |
- Norén, Bengt, et al.
(författare)
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Visual assessment of biliary excretion of Gd-EOB-DTPA in patients with suspected diffuse liver disease–A biopsy-verified prospective study
- 2015
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Ingår i: European Journal of Radiology Open. - : Elsevier BV. - 2352-0477. ; 2, s. 19-25
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To qualitatively evaluate late dynamic contrast phases, 10, 20 and 30. min, after administration of Gd-EOB-DTPA with regard to biliary excretion in patients presenting with elevated liver enzymes without clinical signs of cirrhosis or hepatic decompensation and to compare the visual assessment of contrast agent excretion with histo-pathological fibrosis stage, contrast uptake parameters and blood tests. Methods: 29 patients were prospectively examined using 1.5T MRI. The visually assessed presence or absence of contrast agent for each of five anatomical regions in randomly reviewed time-series was summarized on a four grade scale for each patient. The scores, including a total visual score, were related to the histo-pathological findings, the quantitative contrast agent uptake parameters, expressed as KHep or LSC_N, and blood tests. Results: No relationship between the fibrosis grade or contrast uptake parameters could be established. A negative correlation between the visual assessment and alkaline phosphatase (ALP) was found. Comparing a sub-group of cholestatic patients with fibrosis score and Gd-EOB-DTPA dynamic parameters did not add any additional significant correlation. Conclusions: No correlation between visually assessed biliary excretion of Gd-EOB-DTPA and histo-pathological or contrast uptake parameters was found. A negative correlation between the visual assessment and alkaline phosphatase (ALP) was found.
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| 18. |
- Sahlin, Karin, 1991, et al.
(författare)
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Nanocellulose in biocomposites
- 2016
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Ingår i: Proc Materials for Tomorrow 2016. ; , s. Nr 41-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
- Sahlin, Karin, 1991, et al.
(författare)
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Surface treatment of cellulose nanocrystals (CNC): effects on dispersion rheology
- 2018
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 25:1, s. 331-345
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanocrystals (CNC) were surface modified by grafting azetidinium salts onto the sulphate ester groups on the cellulosic surfaces. The modified CNC were characterized using NMR, FTIR spectroscopy, conductometric titration and measurement of the zeta-potential. Thermal gravimetrical analysis revealed that the onset temperature for the thermal degradation was shifted upwards by almost 100 degrees C as a result of the surface grafting. The rheological properties of dispersions based on unmodified and modified CNC were evaluated in detail. Two solids contents were studied; 0.65 and 1.3 wt%. In general, the grafting of the salts significantly increased the shear viscosity at a given shear rate as well as the storage and loss moduli of the dispersions. The CNC concentration at the gel point (network formation) decreased in a corresponding manner when the nanocellulosic particles were surface modified. This may be associated with pronounced hydrophobic attractive interactions between the grafted substituents.
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| 20. |
- Söderberg, Lina, et al.
(författare)
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Transformation. En del av en skulpturstig i Österbybruk : Modell av en pendel
- 2019
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Ingår i: Som en utställning I galleri Sadelmakarlängan I Österbybruk, Uppland. Detta drivs av Katarina Persson som också är projektledare..
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- Katarina Persson har initierat projektet med konstnärsgruppen Transformation som hon tidigare har samarbetat och gjort utställningar med. Jag, Lina Söderberg är medlem i Transformation, och deltagare i detta projekt. Projektet startade i somras med att gruppen träffades i Österbybruk och hade studiebesök och föreläsningar på orten i en vecka. Detta utmynnade i en skissutställning under hösten.
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| 21. |
- Walter, Susanna A, et al.
(författare)
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Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex
- 2016
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Ingår i: PLOS ONE. - San Francisco, CA, United States : Public Library of Science. - 1932-6203. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD) responses in functional magnetic resonance imaging (fMRI) is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.
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