| 1. |
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| 2. |
- Bergquist, Annika, et al.
(författare)
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Increased risk of primary sclerosing cholangitis and ulcerative colitis in first-degree relatives of patients with primary sclerosing cholangitis
- 2008
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Ingår i: Clinical Gastroenterology and Hepatology. - New York : Elsevier. - 1542-3565 .- 1542-7714. ; 6:8, s. 939-943
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: The importance of genetic factors for the development of primary sclerosing cholangitis (PSC) is incompletely understood. This study assessed the risk of PSC and inflammatory bowel disease (IBD) among first-degree relatives of patients with PSC, compared with the first-degree relatives of a cohort without PSC. Methods: Subjects from the national Swedish cohort of PSC patients (n = 678) were matched for date of birth, sex, and region to up to 10 subjects without a diagnosis of PSC (n = 6347). Linkage through general population registers identified first-degree relatives of subjects in both the PSC and comparison cohorts (n = 34,092). Diagnoses among first-degree relatives were identified by using the Inpatient Register. Results: The risk of cholangitis was statistically significantly increased in offspring, siblings, and parents of the PSC patient cohort, compared with relatives of the comparison cohort, with the hazard ratios and 95% confidence intervals, 11.5 (1.6–84.4), 11.1 (3.3–37.8), and 2.3 (0.9–6.1), respectively. The hazard ratios for ulcerative colitis (UC) among first-degree relatives of all PSC patients was 3.3 (2.3–4.9) and for Crohn's disease 1.4 (0.8–2.5). The risk of UC for relatives of PSC patients without IBD was also increased, 7.4 (2.9–18.9). Conclusions: First-degree relatives of patients with PSC run an increased risk of PSC, indicating the importance of genetic factors in the etiology of PSC. First-degree relatives of PSC patients without IBD are also at an increased risk of UC, which might indicate shared genetic susceptibility factors for PSC and UC.
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| 3. |
- Löfberg, Robert, et al.
(författare)
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Oral budesonide versus prednisolone in patients with extensive and left sided ulcerative colitis
- 1996
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Ingår i: Gastroenterology. - : Elsevier BV. - 1528-0012 .- 0016-5085. ; 110:6, s. 1713-1718
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Systemic glucocorticosteroids (GCSs) have proven efficacy in active ulcerative colitis but cause undesired systemic side effects. Therefore, new GCSs with high topical activity and a high rate of metabolism may be of clinical value in this condition. The aim of this study was to explore the efficacy and safety of the topically acting GCS budesonide in an oral controlled-release formulation in extensive or left-sided, mild to moderately active ulcerative colitis. METHODS: A 9-week, randomized, double-blind, controlled trial was performed, and treatments with 10 mg budesonide or 40 mg prednisolone daily, both gradually tapered, were compared. Endoscopic improvement and effect on endogenous plasma cortisol were assessed. RESULTS: Thirty-four patients were administered budesonide, and 38 patients were administered prednisolone. Mean endoscopic scores improved significantly in both groups but without difference between the groups. Five patients in the budesonide group and 7 patients in the prednisolone group deteriorated and were withdrawn from the study. Morning plasma cortisol levels were suppressed in the prednisolone group (entry, 449 nmol/L; 2 weeks, 116 nmol/L; 4 weeks, 195 nmol/L) but were unchanged in the budesonide group. CONCLUSIONS: The GCS budesonide administered in an oral controlled-release formulation seems to give an overall treatment result in active ulcerative colitis approaching that of prednisolone but without suppression of plasma cortisol levels. This concept merits further evaluation.
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| 4. |
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| 5. |
- Ahlgren, Joakim, et al.
(författare)
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Biogenic phosphorus in oligotropic mountain lake sediments: Differences in composition measured with NMR spectroscopy
- 2006
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Ingår i: Water Research. - Uppsala Univ, Dept Phys & Analyt Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Organ & Biol Chem, S-75123 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, EBC, S-75236 Uppsala, Sweden. : Elsevier BV. - 0043-1354 .- 1879-2448. ; :40, s. 3705-3712
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Aleman, Soo, et al.
(författare)
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Health check-ups and family screening allow detection of hereditary hemochromatosis with less advanced liver fibrosis and survival comparable with the general population
- 2011
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 46:9, s. 1118-1126
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The information concerning the morbidity and mortality of hereditary hemochromatosis is based primarily on clinical cohorts of symptomatic patients. The major aim of this study was to analyze the long-term prognosis for Swedish patients with this condition, with respect to both clinical features and survival, in relation to the route by which the disease was detected. Patients and methods. 373 patients with hemochromatosis detected through routine health checkups (n = 153), family screening (n = 44), symptoms of arthralgia (n = 23), investigation of other diseases/symptoms (n = 108) or signs of liver disease (n = 45) were monitored for a mean period of 11.9 +/- 5.8 years. The degree of liver fibrosis and survival were analyzed. Results. Overall survival among these patients was not significantly different from that of a matched normal population. The patients diagnosed through health check-ups and family screening were detected at an earlier age and had the highest rate of survival. Liver biopsy at the time of diagnosis revealed cirrhosis in 9% of those detected through the health check-ups and 5% in the case of family screening, compared with 13% for the group with arthralgia, 17% for other diseases/symptoms and 42% for liver disease. Conclusion. Health check-ups and family screening allow detection of hereditary hemochromatosis at an earlier age and with less advanced liver fibrosis, although a few of these patients have already developed cirrhosis. Our study indicates that iron indices should be included in health check-ups, and if abnormal, should lead to further investigation.
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| 7. |
- Allard, Erik, et al.
(författare)
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Comparing capillary electrophoresis : mass spectrometry fingerprints of urine samples obtained after intake of coffee, tea, or water.
- 2008
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 80:23, s. 8946-8955
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Tidskriftsartikel (refereegranskat)abstract
- Metabolomic fingerprinting is a growing strategy for characterizing complex biological samples without detailed prior knowledge about the metabolic system. A two-way analysis system with liquid separation and mass spectrometric detection provides detail-rich data suitable for such fingerprints. As a model study, human urine samples, obtained after intake of coffee, tea, or water, were analyzed with capillary electrophoresis electrospray ionization time-of-flight mass spectrometry (CE−ESI-TOF-MS). In-house-developed software (in Matlab) was utilized to manage and explore the large amount of data acquired (230 CE−MS runs, each with 50−100 million nonzero data points). After baseline and noise reduction, followed by suitable binning in time and m/z, the data sets comprised 9 and 14 million data points in negative and positive ESI mode, respectively. Finally, a signal threshold was applied, further reducing the number to about 100 000 data points per data set. A set of interactive exploratory tools, utilizing principal component analysis (PCA) and analysis of variance (ANOVA) results based on a general linear model, facilitated visual interpretation with score plots (for group assessment) and differential fingerprints (for “hot spot” detection). In the model study highly significant differences due to beverage intake were obtained among the 10 first principal components (p < 10−6 for two of the components in both ESI modes). Especially, the contrasts between “coffee” and “tea or water” indicated several “hot spots” with highly elevated intensities (e.g., for uncharged masses 93, 94, 109, 119, 123, 132, 148, 169, 178, 187, 190, and 193) suitable for further analysis, for example, with tandem MS.
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| 8. |
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| 9. |
- Alsterlund, Rolf, et al.
(författare)
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Yersinia enterocolitica-utbrott på Bjärehalvön visar på risker med kylda matvaror
- 1995
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Ingår i: Läkartidningen. - Stockholm : Sveriges läkarförbund. - 0023-7205 .- 1652-7518. ; 92:12, s. 1213-1214
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Tidskriftsartikel (refereegranskat)abstract
- På sensommaren 1988 hade man i Skåne ett stort lokalt utbrott med 61 fall av infektioner med Yersinia enterocolitica. DEn kliniska bilden var avsevärt mildare än som brukar rapporteras, med diarré, magsmärtor och feber som dominerande symtom, och endast två fall av svårare komplikationer. Den sannolika smittkällan var mjölk från ett litet mejeri där hygienen inte var den bästa, Utbrottet visar på en av många risker med distribution av industriellt framställda kylda livsmedel.
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| 10. |
- Amirkhani, Ardeshir, et al.
(författare)
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Comparison between different sheathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography time-of-flight mass spectrometry analysis
- 2004
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1033:2, s. 257-266
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Tidskriftsartikel (refereegranskat)abstract
- Four different sheathless electrospray ionization (ESI) configurations were investigated for a nano liquid chromatography (LC) system. The studied configurations were: a column with an integrated emitter, with the ESI potential applied before or after the column, and a column with separate emitter, with the ESI voltage applied at a union before the emitter or at the emitter tip. The results indicates that the efficiency of the LC system is rather independent of the configuration when using 95 μm i.d. columns, acetic mobile phase and standard peptides as a sample. Introduction of post column dead volume seems not to be a critical issue at least with flow rates down to 600 nl/min.
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| 11. |
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| 12. |
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| 13. |
- Aspholm, Marina, et al.
(författare)
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Helicobacter pylori adhesion to carbohydrates
- 2006
-
Ingår i: Methods in Enzymology. - 0076-6879 .- 1557-7988. ; 417, s. 293-339
-
Tidskriftsartikel (refereegranskat)abstract
- Adherence of bacterial pathogens to host tissues contributes to colonization and virulence and typically involves specific interactions between bacterial proteins called adhesins and cognate oligosaccharide (glycan) or protein motifs in the host that are used as receptors. A given pathogen may have multiple adhesins, each specific for a different set of receptors and, potentially, with different roles in infection and disease. This chapter provides strategies for identifying and analyzing host glycan receptors and the bacterial adhesins that exploit them as receptors, with particular reference to adherence of the gastric pathogen Helicobacter pylori.
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| 14. |
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| 15. |
- Behling, Rolf, et al.
(författare)
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Microparticle Hybrid Target Simulation for keV X-ray Sources
- 2024
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Ingår i: Instruments. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2410-390X. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- The spatiotemporal resolution of diagnostic X-ray images obtained with rotating-anode X-ray tubes has remained limited as the development of rigid, high-performance target materials has slowed down. However, novel imaging techniques using finer detector pixels and orthovolt cancer therapy employing narrow X-ray focal spots demand improved output from brilliant keV X-ray sources. Since its advent in 1929, rotating-anode technology has become the greatest bottleneck to improvement. To overcome this limitation, the current authors have devised a novel X-ray generation technology based on tungsten microparticle targets. The current study investigated a hybrid solution of a stream of fast tungsten microparticles and a rotating anode to both harvest the benefits of the improved performance of the new solution and to reuse known technology. The rotating anode captures energy that may pass a partially opaque microparticle stream and thereby contributes to X-ray generation. With reference to fast-rotating anodes and a highly appreciated small focal spot of a standardized size of 0.3 for an 8° target angle (physical: 0.45 mm × 4.67 mm), we calculated a potential output gain of at least 85% for non-melting microparticles and of 124% if melting is envisioned. Microparticle charging can be remediated by electron backscattering and electron field emission. The adoption of such a solution enables substantially improved image resolution.
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| 16. |
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| 17. |
- Bergström, Sara K., et al.
(författare)
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Screening of microdialysates taken before and after induced liver damage; on-line solid phase extraction-electrospray ionization-mass spectrometry
- 2006
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1120:1-2, s. 21-26
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method is described to follow known and unknown compounds in biological processes using microdialysis sampling and mass spectrometric detection. By implementation of internal standard, desalting/enrichment for the sample work-up, and multivariate data analysis, this methodology is a basis for future applications in early diagnosis of diseases and organ damage, as a complement to the routinely used clinical methods for biological samples. The present study includes screening without specific target analytes, of samples collected by microdialysis from liver of anaesthetized rats before and after local damage to this organ. Sample series were classified by principal component analysis, and the stimulation was identified in the chemical patterns produced by the presented analytical tool.
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| 18. |
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| 19. |
- Björk, Staffan, et al.
(författare)
-
WEST: A Web Browser for Small Terminals
- 1999. - 1
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Konferensbidrag (refereegranskat)abstract
- We describe WEST, a WEb browser for Small Terminals, that aims to solve some of the problems associated with accessing web pages on hand-held devices. Through a novel combination of text reduction and focus+context visualization, users can access web pages from a very limited display environment, since the system will provide an overview of the contents of a web page even when it is too large to be displayed in its entirety. To make maximum use of the limited resources available on a typical hand-held terminal, much of the most demanding work is done by a proxy server, allowing the terminal to concentrate on the task of providing responsive user interaction. The system makes use of some interaction concepts reminiscent of those defined in the Wireless Application Protocol (WAP), making it possible to utilize the techniques described here for WAP-compliant devices and services that may become available in the near future.
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| 20. |
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| 21. |
- Bylund, Dan, et al.
(författare)
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Chromatographic alignment by warping and dynamic programming as a pre-processing tool for PARAFAC modelling of liquid chromatography-mass spectrometry data
- 2002
-
Ingår i: Journal of Chromatography A. - 0021-9673. ; 961:2, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- Solutes analysed with LC–MS are characterised by their retention times and mass spectra, and quantified by the intensities measured. This highly selective information can be extracted by multiway modelling. However, for full use and interpretability it is necessary that the assumptions made for the model are valid. For PARAFAC modelling, the assumption is a trilinear data structure. With LC–MS, several factors, e.g. non-linear detector response and ionisation suppression may introduce deviations from trilinearity. The single largest problem, however, is the retention time shifts not related to the true sample variations. In this paper, a time warping algorithm for alignment of LC–MS data in the chromatographic direction has been examined. Several refinements have been implemented and the features are demonstrated for both simulated and real data. With moderate time shifts present in the data, pre-processing with this algorithm yields approximately trilinear data for which reasonable models can be made.
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| 22. |
- Bylund, Dan, et al.
(författare)
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Peak purity assessment in liquid chromatography-mass spectrometry
- 2001
-
Ingår i: Journal of Chromatography A. - 0021-9673. ; 915:1/2, s. 43-52
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Tidskriftsartikel (refereegranskat)abstract
- Fixed-size moving window evolving factor analysis and base peak chromatograms have been used for peak purity detection in data generated with LC–MS. The two methods were evaluated with both real and simulated data and were found to be fast and complementary to each other. When a possibly impure peak is detected, it is suggested that further information can be obtained from local principal component analysis modelling and comparative mass chromatogram plots.
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| 23. |
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| 24. |
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| 25. |
- Bäckström, Daniel, 1973-
(författare)
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Managing and Exploring Large Data Sets Generated by Liquid Separation - Mass Spectrometry
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A trend in natural science and especially in analytical chemistry is the increasing need for analysis of a large number of complex samples with low analyte concentrations. Biological samples (urine, blood, plasma, cerebral spinal fluid, tissue etc.) are often suitable for analysis with liquid separation mass spectrometry (LS-MS), resulting in two-way data tables (time vs. m/z). Such biological 'fingerprints' taken for all samples in a study correspond to a large amount of data. Detailed characterization requires a high sampling rate in combination with high mass resolution and wide mass range, which presents a challenge in data handling and exploration. This thesis describes methods for managing and exploring large data sets made up of such detailed 'fingerprints' (represented as data matrices). The methods were implemented as scripts and functions in Matlab, a wide-spread environment for matrix manipulations. A single-file structure to hold the imported data facilitated both easy access and fast manipulation. Routines for baseline removal and noise reduction were intended to reduce the amount of data without loosing relevant information. A tool for visualizing and exploring single runs was also included. When comparing two or more 'fingerprints' they usually have to be aligned due to unintended shifts in analyte positions in time and m/z. A PCA-like multivariate method proved to be less sensitive to such shifts, and an ANOVA implementation made it easier to find systematic differences within the data sets. The above strategies and methods were applied to complex samples such as plasma, protein digests, and urine. The field of application included urine profiling (paracetamole intake; beverage effects), peptide mapping (different digestion protocols) and search for potential biomarkers (appendicitis diagnosis) . The influence of the experimental factors was visualized by PCA score plots as well as clustering diagrams (dendrograms).
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| 26. |
- Bäckström, Daniel, et al.
(författare)
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Multivariate comparison between peptide mass fingerprints obtained by liquid chromatography-electrospray ionization-mass spectrometry with different trypsin digestion procedures
- 2007
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1171:1-2, s. 69-79
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Tidskriftsartikel (refereegranskat)abstract
- Peptide mass fingerprints were obtained for three different proteins using three different digestion procedures in triplicates with liquid chromatography coupled to electrospray ionization mass spectrometry. For each protein the results were compared with multivariate data analysis (cluster analysis, kernel principal component analysis) and pair-wise contrast evaluation. Clear systematic differences between the digestion procedures were established for all the proteins. The visual presentation of the pair-wise differences between procedures could to some extent be related to the protein fragments, although the main objective was to identify m/z and retention regions in the original peptide maps that should be subject to further exploration.
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| 27. |
- Danielsson Borssén, Åsa, et al.
(författare)
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Hepatocellular and extrahepatic cancer in patients with autoimmune hepatitis : a long-term follow-up study in 634 Swedish patients
- 2015
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa Healthcare. - 0036-5521 .- 1502-7708. ; 50:2, s. 217-223
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives. Cirrhosis is a well-known risk factor for hepatocellular cancer, but the true risk in autoimmune hepatitis (AIH) is scarcely studied. Other cancers may arise after prolonged use of immune-modulating drugs. The aim of this study was to investigate the cancer risk in a large cohort of AIH patients.Material and methods. Six hundred and thirty-four Swedish patients in a well-defined cohort were matched to the Cause of Death Registry and the Cancer Registry. Standard incidence ratios were calculated by relating the incidences in the cohort to an age-matched material from the Swedish background population.Results. A higher overall incidence of malignancies than the background population was found, counting from the date of diagnosis (standard incidence ratio (SIR) 2.08, 95% CI 1.68-2.55). The highest risk was found for hepatocellular carcinoma (HCC). We found 10 cases (4.0%) in 248 patients with cirrhosis, which gives an incidence rate of 0.3%. Standard incidence ratio for developing hepatobiliary cancer was 54.55 (95% CI 19.92-99.99). HCC only occurred in cirrhotic patients. There was also an increased risk for non-melanoma skin cancer (SIR 9.87, 95% CI 6.26-14.81).Conclusion. A slightly enhanced risk for malignancies in general compared to the background population was found. The risk of hepatobiliary cancer was increased, but the annual risk over the observational period was well under the postulated 1.5% when surveillance in cirrhotic patients is considered to be cost-effective.
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| 28. |
- Danielsson, Rolf, 1949-
(författare)
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Bohusmodellen
- 1993
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Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :4, s. 49-50
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- I samarbete mellan Byggnadsstyrelsen, Kungälvs kommun och Länsarbetsnämnden pågår sedan hösten 1990 ett omfattande iståndsättningsarbete på Bohus fästning. Arbetet har främst bestått av uppsnyggning av området samt omfogning av murytor. Bohus fästning är ett statligt byggnadsminne och förvaltas av Byggnadsstyrelsen. Antikvarisk kontrollant är Riksantikvarieämbetet genom Bohusläns Museum i Uddevalla.
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| 29. |
- Danielsson, Rolf, et al.
(författare)
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Cadmium in moose kidney and liver : age and gender dependency, and standardisation for environmental monitoring
- 2009
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Ingår i: Environmental Monitoring & Assessment. - : Springer Science and Business Media LLC. - 0167-6369 .- 1573-2959. ; 157:1-4, s. 73-88
-
Tidskriftsartikel (refereegranskat)abstract
- In the northern hemisphere moose has been found to be suitable as a monitoring animal for the presence of cadmium in the environment. The metal accumulates mainly in the kidney and the liver, with the rate of accumulation dependent on age and possibly also on gender. Collection of tissue material often results in sample selections with disparate age and gender composition, which makes comparison between different regions and different studies difficult. A previous large scale investigation of metals in kidney and liver from moose in Sweden provided Cd data (n = 3,817 and 3,802, respectively) to further explore the relation between Cd accumulation and age/gender. Based on local averages, the individual deviations were analysed with respect to the factors age and gender resulting in an 'ageing function' for each gender and organ. In addition, estimates of the pure individual variations were obtained; the standard deviations correspond to a factor 1.7-1.9 for the Cd concentration, which indicates that 25-30 samples are needed to give a representative mean value (with RSD ≈ 10%). In order to be able to compare results from different studies, all individual results can be transformed to represent a 'standard moose' with respect to age and gender. A comparison along these lines was undertaken between Cd levels in Alaska and Sweden. Finally, a relationship between the Cd levels in kidney and liver was derived, providing at least rough estimates for kidney from liver values (or vice versa).
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| 30. |
- Danielsson, Rolf, et al.
(författare)
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Exploring liquid chromatography-mass spectrometry fingerprints of urine samples from patients with prostate or urinary bladder cancer
- 2011
-
Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 108:1, s. 33-48
-
Tidskriftsartikel (refereegranskat)abstract
- Data processing and analysis have become true rate and success limiting factors for molecular research where a large number of samples of high complexity are included in the data set. In general rather complicated methodologies are needed for the combination and comparison of information as obtained from selected analytical platforms. Although commercial as well as freely accessible software for high-throughput data processing are available for most platforms, tailored in-house solutions for data management and analysis can provide the versatility and transparency eligible for e.g. method development and pilot studies. This paper describes a procedure for exploring metabolic fingerprints in urine samples from prostate and bladder cancer patients with a set of in-house developed Matlab tools. In spite of the immense amount of data produced by the LC-MS platform, in this study more than 1010 data points, it is shown that the data processing tasks can be handled with reasonable computer resources. The preprocessing steps include baseline subtraction and noise reduction, followed by an initial time alignment. In the data analysis the fingerprints are treated as 2-D images, i.e. pixel by pixel, in contrast to the more common list-based approach after peak or feature detection. Although the latter approach greatly reduces the data complexity, it also involves a critical step that may obscure essential information due to undetected or misaligned peaks. The effects of remaining time shifts after the initial alignment are reduced by a binning and [‘]blurring’ procedure prior to the comparative multivariate and univariate data analyses. Other factors than cancer assignment were taken into account by ANOVA applied to the PCA scores as well as to the individual variables (pixels). It was found that the analytical day-to-day variations in our study had a large confounding effect on the cancer related differences, which emphasizes the role of proper normalization and/or experimental design. While PCA could not establish significant cancer related patterns, the pixel-wise univariate analysis could provide a list of about a hundred [‘]hotspots’ indicating possible biomarkers. This was also the limited goal for this study, with focus on the exploration of a really huge and complex data set. True biomarker identification, however, needs thorough validation and verification in separate patient sets.
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| 31. |
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| 32. |
- Danielsson, Rolf, et al.
(författare)
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Matched filtering with background suppression for improved quality of base peak chromatograms and mass spectra in liquid chromatography-mass spectrometry
- 2002
-
Ingår i: Analytica Chimica Acta. - 0003-2670. ; 454:2, s. 167-184
-
Tidskriftsartikel (refereegranskat)abstract
- A time domain filter that combines the properties of matched filtering and two-fold differentiation is presented. The filter coefficients are given by the second derivative of a Gaussian model peak, controlled by the setting of two parameters related to the chromatographic system. The fundamental characteristics of the filter were derived, and its applicability demonstrated for real liquid chromatography–mass spectrometry (LC–MS) data. The filter is primarily intended as a fast pre-processing step, for a mass chromatogram with 320 scans over 700 mass channels the computation time was 0.6 s on a standard PC. Base peak chromatograms with improved peak detection capability and mass spectra useful for compound identification were obtained with filtered data. The most significant effect of the described filter is background reduction due to the differentiation, which in combination with the matched filter can be performed with maintained or even improved signal-to-noise ratio.
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| 33. |
- Danielsson, Rolf, et al.
(författare)
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Rapid multivariate analysis of LC/GC/CE data (single or multiple channel detection) without prior peak alignment
- 2006
-
Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 84:1-2, s. 33-39
-
Tidskriftsartikel (refereegranskat)abstract
- One- or two-dimensional data obtained with LC/GC/CE and single or multiple channel detection (MS, UV/VIS) are often used as 'fingerprints' in order to characterize complex samples. The relation between samples is then explored by multivariate data analysis (PCA, hierarchical clustering), but inevitable more or less random variation in separation conditions obstructs the analysis. Several methods for peak alignment have been developed, with more or less increase of time and efforts for computations. In this work another approach is presented, based on a correlation measure less sensitive for variations in retention/migration time. The merits of the method as a fast initial data exploration tool are demonstrated for a case study of urine profiling with CE/MS.
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| 34. |
- Daszykowski, M., et al.
(författare)
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No-alignment-strategies for exploring a set of two-way data tables obtained from capillary electrophoresis-mass spectrometry
- 2008
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1192:1, s. 157-165
-
Tidskriftsartikel (refereegranskat)abstract
- Hyphenated techniques such as capillary electrophoresis-mass spectrometry (CE-MS) or high-performance liquid chromatography with diode array detection (HPLC-DAD), etc., are known to produce a huge amount of data since each sample is characterized by a two-way data table. In this paper different ways of obtaining sample-related information from a set of such tables are discussed. Working with original data requires alignment techniques due to time shifts caused by unavoidable variations in separation conditions. Other pre-processing techniques have been suggested to facilitate comparison among samples without prior peak alignment, for example, 'binning' and/or 'blurring' the data along the time dimension. All these techniques, however, require optimization of some parameters, and in this paper an alternative parameter-free method is proposed. The individual data tables (X) are represented as Gram matrices (XXT), where the summation is taken over the time dimension. Hence the possible variations in time scale are eliminated, while the time information is at least partly preserved by the correlation structure between the detection channels. For comparison among samples, a similarity matrix is constructed and explored by principal component analysis and hierarchical clustering. The Gram matrix approach was tested and compared to some other methods using 'binned' and 'blurred' data for a data set with CE-MS runs on urine samples. In addition to data exploration by principal component analysis and hierarchical clustering, a discriminant partial least squares model was constructed to discriminate between the samples that were taken with and without the prior intake of a drug. The result showed that the proposed method is at least as good as the others with respect to cluster identification and class prediction. A distinct advantage is that there is no need for parameter optimization, while a potential drawback is the large size of the Gram matrices for data with high mass resolution.
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| 35. |
- De Brabandere, Heidi, 1980-
(författare)
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Organic Phosphorus Compounds in Aquatic Sediments : Towards Molecular Identification with Mass Spectrometry
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus (P) regulates trophic status in most aquatic systems. However, only bioavailable P contributes to primary production. In most lakes and shallow seas, mineralisation of sediment P into its bioavailable form and its release to the water column is important for maintaining primary production. Sediment organic P forms a substantial proportion of this P to be mineralised and can originate from different sources on land (farmland, forests, etc.) or from primary production in the lake. These organic P forms can thus be expected to have differing composition, degradability and recyclable P content. Knowledge of the chemical structure of sediment organic P compounds is scarce, mainly due to lack of appropriate analytical techniques. The commonly used 31P-nuclear magnetic resonance (31P-NMR) technique, only identifies P binding groups, so a mass spectrometric (MS) analysis method was developed that allows individual sediment organic P compounds to be identified. EDTA as pre-extractant resulted in the highest P yield in subsequent NaOH extraction. Extracted organic P compound groups were identified using 31P-NMR. For identification of specific P compounds with MS, a sample preparation method prior to electrospray tandem mass spectrometry (ESI-MS/MS) analysis was developed. Liquid chromatography (LC) with porous graphitic carbon prior to ESI-MS/MS enhanced sensitivity and selectivity, enabling several of the ions detected to be identified as nucleotides. 31P-NMR analysis showed P monoesters to be the most stabile P compounds throughout a lake sediment profile. The developed LC-ESI-MS/MS analysis method revealed that some monoester-P (nucleotides) were labile, while other P compounds increased in concentration with Baltic Sea sediment depth and were therefore considered stabile. Differences in patterns of P compounds detected were also shown depending on catchment characteristics in relation to Baltic Sea sediment age. For cost-effective management of eutrophication, knowledge of the sources of degradable organic P forms, contributing to internal loading, is needed. This thesis showed the developed LC-ESI-MS/MS analysis method to be a powerful analytical tool for this purpose.
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| 36. |
- De Brabandere, Heidi, et al.
(författare)
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Sediment extraction and clean-up for organic phosphorus analysis by electrospray ionization tandem mass spectrometry
- 2008
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 74:5, s. 1175-1183
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Tidskriftsartikel (refereegranskat)abstract
- A method to prepare NaOH sediment extracts for organic P compound analysis with electrospray ionization tandem mass spectrometry (ESI-MS-MS) was developed on natural samples. Ion exchange, rotary evaporation and mass cut-off filtering proved to be suitable for sample preparation. Samples were analyzed with ESI-MS-MS, and reproducibility and repeatability of the method was calculated. In addition, 31P-nuclear magnetic resonance spectroscopy (31P NMR) was used to measure recovery of different P compound groups such as orthophosphate (Ortho-P), orthophosphate monoesters (Monoester-P), orthophosphate diesters (Diester-P) and pyrophosphates (Pyro-P). The developed sample preparation method resulted in an easy-to-spray liquid for the ESI-MS-MS instrumentation. The overall P recovery was 65% and 31P NMR showed that Diester-P, possibly in the form of DNA, was apparently lost through the filtering step most likely due to their size. Variances in the total intensities of the MS scans (relative standard deviation (R.S.D.) 35–54%) were for about 50% due to repeated MS runs. Covariances of the peaks in the MS spectra were calculated to be for about 30% due to the sample preparation procedure. Finally, with the ESI-MS-MS approach, 11 peaks in the mass spectra were found likely to represent phosphate containing compounds.
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| 37. |
- Eriksson, Olle, 1967-
(författare)
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Sensitivity and Uncertainty Analysis Methods : with Applications to a Road Traffic Emission Model
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is always a need to study the properties of complex input–output systems, properties that may be very difficult to determine. Two such properties are the output’s sensitivity to changes in the inputs and the output’s uncertainty if the inputs are uncertain.A system can be formulated as a model—a set of functions, equations and conditions that describe the system. We ultimately want to study and learn about the real system, but with a model that approximates the system well, we can study the model instead, which is usually easier. It is often easier to build a model as a set of combined sub-models, but good knowledge of each sub-model does not immediately lead to good knowledge of the entire model. Often, the most attractive approach to model studies is to write the model as computer software and study datasets generated by that software.Methods for sensitivity analysis (SA) and uncertainty analysis (UA) cannot be expected to be exactly the same for all models. In this thesis, we want to determine suitable SA and UA methods for a road traffic emission model, methods that can also be applied to any other model of similar structure. We examine parts of a well-known emission model and suggest a powerful data-generating tool. By studying generated datasets, we can examine properties in the model, suggest SA and UA methods and discuss the properties of these methods. We also present some of the results of applying the methods to the generated datasets.
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| 38. |
- Eriksson, Rolf, et al.
(författare)
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Method and arrangement relating to an x-ray imaging apparatus
- 2004
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Patent (populärvet., debatt m.m.)abstract
- The present invention relates to an arrangement for adjusting a number of settings in an x-ray imaging apparatus (10) for recurrent mammography examinations, said apparatus comprising at least one x-ray source (11), a collimator arrangement (12) and compression pedals (13a, 13b) for positioning and compressing the breast (14) of a patient to be examined. The arrangement comprises: control units (16-19) for adjusting said number of settings of said x-ray imaging apparatus based on an identity of said person to be examined and data stored in a database (21), said data including a set of setting-data from at least one recent x-ray examination of said patient, a main control unit (15) communicating with a control unit (16) for adjusting characteristics of x-ray radiations from said x-ray source (11), a control unit (17) for adjusting the position of said x-ray source (11) and an identity input device (20). The arrangement further comprises a device (19) for adjusting collimator slots widths based on information retrieved from said database and/or a position of said pedals.
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| 39. |
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| 40. |
- Frank, Adrian, et al.
(författare)
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Comparison of two monitoring systems for Cu and Mo in the Swedish environment
- 2004
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Ingår i: Science of the Total Environment. ; :330, s. 131-143
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Tidskriftsartikel (refereegranskat)abstract
- Bio-geochemical samples (BGS) are roots of certain aquatic plants and mosses suitable for monitoring elements dissolved in stream water. The moose, a wild ruminant living in most parts of Sweden, represents higher trophic level and another manifestation of bioavailability. By analyzing BGS (n=33 600) and moose liver (n=2400), a systematic survey has been performedin the terrestrial environment of Sweden. Cu and Mo are essential elements for life, and their presence is especially important for the Cu-dependent processes in ruminants. The availability of Cu and Mo as monitored in BGS and moose was visualized in the form of maps and subjected to further statistical analysis. The medians, with lower and upper quartiles indicated as intervals, for the country as a whole were: moose liver, Cu=34 (20-59), Mo=0.82 (0.58-1.06) mg kg -1 wet weight; BGS, Cu=50 (35-77), Mo=9.0 (5.3-18.0) mg kg -1 dry weight. The ranges of medians for the 22 Swedish counties were: moose liver, Cu=(20-62), Mo=(0.54-1.18) mg kg -1 wet weight; BGS, Cu=(28-115), Mo=(5-47) mg kg -1 dry weight. The relationships between the counties and the connections between the monitoring variables were elucidated by principal component analysis (PCA). It was demonstrated that two monitoring systems could give divergent results. An unexpectedly strong negative correlation was found between the county medians for Cu in BGS and moose liver. A possible explanation, based on the interaction between Cu and Mo in moose, could not be verified.
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| 41. |
- Frank, Adrian, et al.
(författare)
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Nova Scotia moose mystery - a moose sickness related to cobalt- and vitamin B12 deficiency
- 2004
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Ingår i: The Science of the Total Environment. ; :318, s. 89-100
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Tidskriftsartikel (refereegranskat)abstract
- A wasting, debilitating disease with uncertain aetiology, affecting moose (Alces alces americana) in Eastern North America has been reported repeatedly ever since the 1910s. Despite the intensive studies during 1930-1960s the cause of the sickness could not be established. In the 1960s a parasitic nematode (Parelaphostrongylus tenuis) was reported as constituting a probable explanation for the sickness, although several clinical and pathological signs remained unexplained. In Sweden, a moose disease with similar signs, has been shown to be caused by molybdenosis resulting from a nutritional imbalance. The findings of this investigation were applied in Nova Scotia to determine trace element concentrations in tissues from indigenous moose. Co deficiency was found in about half of the cases and the investigation was complemented by determining the vitamin B12 level, which proved nutritional Co/vitamin B12 deficiency, further verified by an increased MMA (methylmalonic acid) level in plasma. Deficiencies were found mainly in the Tobeatic and Cape Breton Highland regions. No indications of molybdenosis or other trace element disturbances were found in Nova Scotia. Otherwise, extremely high Cd levels (148 mg Cd/kg kidney wet wt., maximum) were found, though probably not contributing to the moose sickness. The Cd burden of moose on mainland Nova Scotia was more than 50% higher than that of moose in Huntville and Alonquin (Ontario, Canada) and five- to six-fold is higher than the highest Cd levels found in Sweden. To counteract the bio-geochemical effects of Co deficiency in the moose environment, provision of Co-containing salt licks is suggested.
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| 42. |
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| 43. |
- Geibe, Christine, et al.
(författare)
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Comparison of soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters
- 2006
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 21:12, s. 2096-2111
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Tidskriftsartikel (refereegranskat)abstract
- The choice of sampling method for soil solution is of great importance. In this paper soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters have been studied with the purpose of investigating systematic differences between them. The samples were taken at 4 depths from an acidified forest soil as well as from adjacent lime and ash treated soils. A centrifugation drainage method was compared with two types of suction lysimeters ('Rhizon' and 'Prenart') and zero-tension lysimeters. About half of the 27 variables measured showed a significant difference between the sampling methods used. Typically the centrifuged samples had lower pH (4.0 vs. 4.4), Ca (21 mu M vs. 30 mu M) and Mg (25 mu M vs. 34 mu M) concentrations and higher CI (330 mu M vs. 230 mu M) and DOC (4.4 mM vs. 3.2 mM) concentrations than the Rhizon lysimeters. Also the other lysimeters showed significant differences compared to the centrifuged samples for about half the number of analytes. Centrifuged samples had higher concentrations of all analytes except NO3 and PO4 compared to zero-tension lysimeters and also for all analytes except NO3 and Al compared to Prenart lysimeters. Among the environmental factors considered depth showed an influence to some extent, while sampling occasion had a great significant impact on the difference between the centrifugation method and the Rhizon lysimeters. Factors like individual pits or soil treatment did not show any influence on the difference between the methods. (c) 2006 Elsevier Ltd. All rights reserved.
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| 44. |
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| 45. |
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| 46. |
- Johannesson, Nina, et al.
(författare)
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Screening for biomarkers in plasma from patients with gangrenous phlegmonous appendicitis using CE and CEC in combination with MS
- 2007
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 28:9, s. 1435-1443
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Tidskriftsartikel (refereegranskat)abstract
- Today a high degree of "false" appendicitis diagnoses are occurring. In this study, a screening experiment of biomarkers of two different kinds of appendicitis, gangrenous and phlegmonous, were conducted with CE and CEC coupled to MS. Plasma samples were obtained from patients pre- and post-surgery. A large amount of data was generated to be able to compare them, and chemometrics tools were utilized to visualize the differences. Indicative patterns were found for both pre- and post-surgery of the two types of inflammation as well as between them. The divergences were traced back to the MS peaks obtained in the CE- and CEC-MS setups as possible biomarkers for the two forms of appendicitis.
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| 47. |
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| 48. |
- Karling, Pontus, et al.
(författare)
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No difference in symptoms of irritable bowel syndrome between healthy subjects and patients with recurrent depression in remission
- 2007
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Ingår i: Neurogastroenterology and Motility. - Oxford : Blackwell. - 1350-1925 .- 1365-2982. ; 19:11, s. 896-904
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Tidskriftsartikel (refereegranskat)abstract
- There is bidirectional comorbidity between anxiety/depression and irritable bowel syndrome (IBS). To investigate the prevalence of IBS symptoms, and factors associated with gastrointestinal symptoms in patients with recurrent depressive disorder. Patients (n = 95) with recurrent type of major depression according to DSM-IV criteria and sex- and age-matched controls (n = 190) were sent questionnaires investigating symptoms of IBS [Gastrointestinal Symptom Rating Scale (GSRS)-IBS] and symptoms of anxiety and depression [Hospital Anxiety and Depression Scale (HADS)]. Medical records were checked over a 10-year period for chronic somatic symptoms or diseases. Seventy-three patients with unipolar disorder (mean age 63.6 years SD 13.8; range 23–86 years) and 156 controls (mean age 59.2 years SD 11.6, range 21–85 years) responded. Patients with recurrent depression had higher GSRS-IBS scores and showed a strong correlation between symptoms of IBS and anxiety-depression (rs = 0.54; P < 0.001). IBS symptoms were also associated with multiple pain symptoms, higher health-seeking behaviour and selective-serotonin-reuptake inhibitor intake. However, patients with recurrent depression (n = 46) in remission (HADS-Depression score <8) did not have more symptoms of IBS than controls (GSRS-IBS median score 6.0 vs 6.5; P = 0.46). There is a strong association between symptoms of IBS and symptoms of anxiety and depression, whereas depressive patients in remission do not have more IBS symptoms than controls.
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| 49. |
- Karling, Pontus, et al.
(författare)
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The relationship between the val158met catechol-o-methyltransferase (COMT) polymorphism and irritable bowel syndrome.
- 2011
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Ingår i: PloS one. - : Public Library of Science. - 1932-6203. ; 6:3, s. e18035-
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Tidskriftsartikel (refereegranskat)abstract
- Background The catechol-O-methyltransferase (COMT) enzyme has a key function in the degradation of catecholamines and a functional polymorphism is val158met. The val/val genotype results in a three to fourfold higher enzymatic activity compared with the met/met genotype, with the val/met genotype exhibiting intermediate activity. Since pain syndromes as well as anxiety and depression are associated to low and high COMT activity respectively and these conditions are all associated with irritable bowel syndrome (IBS) we wanted for the first time to explore the relationship between the polymorphism and IBS. Methodology/Principal Findings 867 subjects (445 women) representative of the general population and 70 consecutively sampled patients with IBS (61 women) were genotyped for the val158met polymorphism and the IBS patients filled out the Hospital-Anxiety-and-Depression-Scale (HADS) questionnaire, and an IBS symptom diary. Results There was a significantly higher occurrence of the val/val genotype in patients compared with controls (30% vs 20%; Chi2 (1) 3.98; p = 0.046) and a trend toward a lower occurrence of the val/met genotype in IBS patients compared with controls (39% vs 49%; Chi2 (1) 2.89; p = 0.089). Within the IBS patients the val/val carriers exhibited significantly increased bowel frequency (2.6 vs 1.8 stools per day; Chi2 (1) 5.3; p = 0.03) and a smaller proportion of stools with incomplete defecation (41% vs 68%; Chi2 (1) 4.3; p = 0.04) compared with the rest (val/met+met/met carriers). The val/val carriers also showed a trend for a smaller proportion of hard stools (0% vs 15%; Chi2 (1) 3.2; p = 0.08) and a higher frequency of postprandial defecation (26% vs 21%; Chi2 (1) 3.0; p = 0.08). Conclusions/Significance In this study we found an association between the val/val genotype of the val158met COMT gene and IBS as well as to specific IBS related bowel pattern in IBS patients.
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| 50. |
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