umu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Sjöström, Michael
Publications (10 of 58) Show all publications
Sjögren, F., Davidsson, K., Sjöström, M. & Anderson, C. D. (2012). Cutaneous Microdialysis: Cytokine Evidence for Altered Innate Reactivity in the Skin of Psoriasis Patients?. AAPS Journal, 14(2), 187-195
Open this publication in new window or tab >>Cutaneous Microdialysis: Cytokine Evidence for Altered Innate Reactivity in the Skin of Psoriasis Patients?
2012 (English)In: AAPS Journal, ISSN 1550-7416, E-ISSN 1550-7416, Vol. 14, no 2, p. 187-195Article in journal (Refereed) Published
Abstract [en]

Cutaneous microdialysis demonstrates cytokine production in living human skin. In the present study, microdialysis samples taken from uninvolved and lesional skin in three test subjects with psoriasis over 24 h have been investigated for cytokine content with a bead-based multiplex immunoassay from Luminex. Concentration curves for a set of Th1/Th2 and pro-inflammatory cytokines measured differed from a reference group of ten subjects without psoriasis. The time to return to near baseline values after innate insertion reactivity is between 9 and 16 h. Post-equilibration levels (17-24 h) for the three main cytokines elevated in the reference group were differentially elevated outside the range of the reference group for interleukin-1β (IL1β) and IL8 but not so for IL6. Two further cytokines, granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-α not generally elevated in the reference group, showed elevated values in the test subjects. Multivariate time series analysis (chemometry) showed that cytokine patterns for the individual test subjects often fell outside the 99% confidence intervals of a model generated from the reference group. In a clinical research situation, cutaneous microdialysis is feasible, gives generally higher cytokine levels than in the blood and generates interpretable data on an individual's reactivity compared with a reference group. This may well prove useful in delineation of pathogenetic issues, selection of appropriate therapy and monitoring of subsequent response in inflammatory dermatoses such as psoriasis.

Keywords
cytokines, dermis, human, microdialysis, multivariate time series analysis
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-52897 (URN)10.1208/s12248-012-9331-z (DOI)000302814900005 ()22374383 (PubMedID)
Available from: 2012-03-05 Created: 2012-03-05 Last updated: 2018-06-08Bibliographically approved
Kusano, M., Jonsson, P., Fukushima, A., Gullberg, J., Sjöström, M., Trygg, J. & Moritz, T. (2011). Metabolite signature during short-day induced growth cessation in populus. Frontiers in Plant Science, 2, Article ID 29.
Open this publication in new window or tab >>Metabolite signature during short-day induced growth cessation in populus
Show others...
2011 (English)In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 2, article id 29Article in journal (Refereed) Published
Abstract [en]

The photoperiod is an important environmental signal for plants, and influences a wide range of physiological processes. For woody species in northern latitudes, cessation of growth is induced by short photoperiods. In many plant species, short photoperiods stop elongational growth after a few weeks. It is known that plant daylength detection is mediated by Phytochrome A (PHYA) in the woody hybrid aspen species. However, the mechanism of dormancy involving primary metabolism remains unclear. We studied changes in metabolite profiles in hybrid aspen leaves (young, middle, and mature leaves) during short-day-induced growth cessation, using a combination of gas chromatography–time-of-flight mass spectrometry, and multivariate projection methods. Our results indicate that the metabolite profiles in mature source leaves rapidly change when the photoperiod changes. In contrast, the differences in young sink leaves grown under long and short-day conditions are less distinct. We found short daylength induced growth cessation in aspen was associated with rapid changes in the distribution and levels of diverse primary metabolites. In addition, we conducted metabolite profiling of leaves of PHYA overexpressor (PHYAOX) and those of the control to find the discriminative metabolites between PHYAOX and the control under the short-day conditions. The metabolite changes observed in PHYAOX leaves, together with those in the source leaves, identified possible candidates for the metabolite signature (e.g., 2-oxo-glutarate, spermidine, putrescine, 4-amino-butyrate, and tryptophan) during short-day-induced growth cessation in aspen leaves.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2011
Keywords
aspen, Phytochrome A, metabolite profiling, GC-TOF-MS, dormancy, growth cessation
National Category
Biological Sciences
Identifiers
urn:nbn:se:umu:diva-46412 (URN)10.3389/fpls.2011.00029 (DOI)000208837500029 ()22629261 (PubMedID)
Funder
Swedish Research CouncilSwedish Research Council FormasThe Kempe Foundations
Available from: 2011-09-01 Created: 2011-09-01 Last updated: 2019-01-30Bibliographically approved
Berglind, R., Leffler, P. & Sjöström, M. (2010). Interactions between pH, potassium, calcium, bromide, and phenol and their effects on the bioluminescence of Vibrio fischeri. Journal of Toxicology and Environmental Health, 73(16), 1102-1112
Open this publication in new window or tab >>Interactions between pH, potassium, calcium, bromide, and phenol and their effects on the bioluminescence of Vibrio fischeri
2010 (English)In: Journal of Toxicology and Environmental Health, ISSN 1528-7394, E-ISSN 1087-2620, Vol. 73, no 16, p. 1102-1112Article in journal (Refereed) Published
Abstract [en]

Little attention has been paid to how the light produced by the bacterium Vibrio fischeri in the Microtox assay is dependent on the concentration of essential ions such as sodium and potassium, and whether the concentrations of these ions affect the sensitivity of the test system to toxic chemicals. Five selected factors, pH, potassium (K(+)), calcium (Ca(2+)), bromide (Br(-)), and phenol (Phe), were simultaneously varied over a set of systematically planned experiments according to a D-optimal design that supported the estimation of a model with linear, quadratic, and two-factor interatcions of the studied factors. The bacterial light production represented by the gamma values in the Microtox assay for the 24 selected combinations of factors was measured at 5 and 15 min. The gamma values varied from negative to positive values greater than 1, indicating stimulation and inhibition of bacterial light production, respectively. The relationship between the gamma values and the factor settings was investigated with multiple linear regression. After 5 min of exposure, the light production was significantly affected by linear and quadratic terms for K(+), pH, and Phe and an interaction between pH and Phe. The situation was more complex after 15 min of exposure, since in addition significant interactions were found for K x Phe and Ca x pH. The tolerance of V. fischeri to Phe was enhanced by increasing the K and Ca concentrations. Data indicate that the ion composition and pH of the sample, as well as the diluents, need to be considered when the toxicity of salts, water samples, and extracts of sediments and soils are tested using commercially certified toxicity test kits.

National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:umu:diva-35262 (URN)10.1080/15287394.2010.482918 (DOI)000279121000003 ()20574912 (PubMedID)
Available from: 2010-08-11 Created: 2010-08-11 Last updated: 2018-06-08Bibliographically approved
Alvehus, M., Burén, J., Sjöström, M., Goedecke, J. & Olsson, T. (2010). The human visceral fat depot has a unique inflammatory profile. Obesity, 18(5), 879-883
Open this publication in new window or tab >>The human visceral fat depot has a unique inflammatory profile
Show others...
2010 (English)In: Obesity, ISSN 1930-7381, E-ISSN 1930-739X, Vol. 18, no 5, p. 879-883Article in journal (Refereed) Published
Abstract [en]

Obesity can be considered as a low-grade inflammatory condition, strongly linked to adverse metabolic outcomes. Obesity-associated adipose tissue inflammation is characterized by infiltration of macrophages and increased cytokine and chemokine production. The distribution of adipose tissue impacts the outcomes of obesity, with the accumulation of fat in visceral adipose tissue (VAT) and deep subcutaneous adipose tissue (SAT), but not superficial SAT, being linked to insulin resistance. We hypothesized that the inflammatory gene expression in deep SAT and VAT is higher than in superficial SAT. A total of 17 apparently healthy women (BMI: 29.3 +/- 5.5 kg/m2) were included in the study. Body fat (dual-energy X-ray absorptiometry) and distribution (computed tomography) were measured, and insulin sensitivity, blood lipids, and blood pressure were determined. Inflammation-related differences in gene expression(real-time PCR) from VAT, superficial and deep SAT biopsies were analyzed using univariate and multivariate data analyses. Using multivariate discrimination analysis, VAT appeared as a distinct depot in adipose tissue inflammation,while the SAT depots had a similar pattern, with respect to gene expression. A significantly elevated (P < 0.01)expression of the CC chemokine receptor 2 (CCR2) and macrophage migration inhibitory factor (MIF) in VAT contributed strongly to the discrimination. In conclusion, the human adipose tissue depots have unique inflammatory patterns, with CCR2 and MIF distinguishing between VAT and the SAT depots.

Place, publisher, year, edition, pages
Nature Publishing Group, 2010
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:umu:diva-34276 (URN)10.1038/oby.2010.22 (DOI)000277234800006 ()20186138 (PubMedID)
Available from: 2010-05-24 Created: 2010-05-24 Last updated: 2018-06-08Bibliographically approved
Samuelsson, R., Thyrel, M., Sjöström, M. & Lestander, T. A. (2009). Effect of biomaterial characteristics on pelletizing properties and biofuel pellet quality. Fuel processing technology, 90(9), 1129-1134
Open this publication in new window or tab >>Effect of biomaterial characteristics on pelletizing properties and biofuel pellet quality
2009 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 90, no 9, p. 1129-1134Article in journal (Refereed) Published
Abstract [en]

Sawdust of conifers as a by-product from saw mills is the most commonly used biomaterial for pellet production in Sweden today. Experiences from the biofuel pellet industry indicate that different biomaterial properties influence the final pellet quality. A systematic study was conducted where five factors were varied according to a two level fractional factorial design. The factors were: tree species (Scots pine, Norway spruce); origin of growth-place (latitudes 57 and 64°N); storage time of sawdust (0 and 140 days), moisture content (9 and 12%) and steam treatment (2 and 6 kg/h). The measured responses bulk density and mechanical durability represented the pellet quality while the press current and the fines produced in the pelletizing process were measures of the pelletizing property.

The results showed that low moisture content and long storage time resulted in increased bulk densities and press currents. For mechanical durability and fines, a long storage time and intermediate moisture contents were found favourable. In addition, indications were found that the reduction of fatty and resin acids during the storage also influenced the pelletizing properties and the pellet quality.

Place, publisher, year, edition, pages
Elsevier, 2009
Keywords
Biomass; Biofuels, Pellet quality, Sawdust, Factorial design
Identifiers
urn:nbn:se:umu:diva-25667 (URN)10.1016/j.fuproc.2009.05.007 (DOI)
Available from: 2009-08-27 Created: 2009-08-27 Last updated: 2018-06-08Bibliographically approved
Nordlund, Å., Johansson, I., Källestål, C., Ericson, T., Sjöström, M. & Strömberg, N. (2009). Improved ability of biological and previous caries multimarkers to predict caries disease as revealed by multivariate PLS modelling. BMC Oral Health, 9(28)
Open this publication in new window or tab >>Improved ability of biological and previous caries multimarkers to predict caries disease as revealed by multivariate PLS modelling
Show others...
2009 (English)In: BMC Oral Health, ISSN 1472-6831, E-ISSN 1472-6831, Vol. 9, no 28Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Dental caries is a chronic disease with plaque bacteria, diet and saliva modifying disease activity. Here we have used the PLS method to evaluate a multiplicity of such biological variables (n=88) for ability to predict caries in a cross-sectional (baseline caries) and prospective (2-year caries development) setting. METHODS: Multivariate PLS modelling was used to associate the many biological variables with caries recorded in thirty 14-year-old children by measuring the numbers of incipient and manifest caries lesions at all surfaces. RESULTS: A wide but shallow gliding scale of one fifth caries promoting or protecting, and four fifths non-influential, variables occurred. The influential markers behaved in the order of plaque bacteria > diet > saliva, with previously known plaque bacteria/diet markers and a set of new protective diet markers. A differential variable patterning appeared for new versus progressing lesions. The influential biological multimarkers (n=18) predicted baseline caries better (ROC area 0.96) than five markers (0.92) and a single lactobacilli marker (0.7) with sensitivity/specificity of 1.87, 1.78 and 1.13 at 1/3 of the subjects diagnosed sick, respectively. Moreover, biological multimarkers (n=18) explained 2-year caries increment slightly better than reported before but predicted it poorly (ROC area 0.76). By contrast, multimarkers based on previous caries predicted alone (ROC area 0.88), or together with biological multimarkers (0.94), increment well with a sensitivity/specificity of 1.74 at 1/3 of the subjects diagnosed sick. CONCLUSION: Multimarkers behave better than single-to-five markers but future multimarker strategies will require systematic searches for improved saliva and plaque bacteria markers.

Place, publisher, year, edition, pages
BioMed Central, 2009
National Category
Dentistry
Identifiers
urn:nbn:se:umu:diva-27771 (URN)10.1186/1472-6831-9-28 (DOI)19886991 (PubMedID)
Available from: 2009-11-19 Created: 2009-11-19 Last updated: 2018-06-08Bibliographically approved
Clothier, R., Dierickx, P., Lakhanisky, T., Fabre, M., Betanzos, M., Curren, R., . . . Anthonissen, R. (2008). A database of IC50 values and principal component analysis of results from six basal cytotoxicity assays, for use in the modelling of the in vivo and in vitro data of the EU ACuteTox project.. Altern Lab Anim, 36(5), 503-19
Open this publication in new window or tab >>A database of IC50 values and principal component analysis of results from six basal cytotoxicity assays, for use in the modelling of the in vivo and in vitro data of the EU ACuteTox project.
Show others...
2008 (English)In: Altern Lab Anim, ISSN 0261-1929, Vol. 36, no 5, p. 503-19Article in journal (Refereed) Published
Abstract [en]

The main aim of the ACuteTox project (part of the EU 6th Framework programme) is to demonstrate that animal tests for acute systemic toxicity can be replaced by alternative in vitro assays. In this project, data for 97 reference chemicals were collected in the AcuBase database, designed to handle deposited in vitro and in vivo (human and animal) data. To demonstrate the applicability of in vitro basal cytotoxicity tests and in vitro-in vivo modelling, it was deemed necessary to obtain data that were generated via defined standard operating procedures. The molar basal cytotoxicity IC50 values (the 50% inhibitory concentrations for the endpoint measured) for a mouse fibroblast cell line (3T3), a human hepatic cell line (HepG2), a rat hepatic cell line (Fa32), and a human neutrophil cell line (HL-60), were compared, and gave an R(2) correlation of 0.83. To identify chemicals that showed differential cytotoxicity to the various cell types involved, principal component analysis (PCA) was undertaken independently, once all the results had been returned. This showed that colchicine, cycloheximide, digoxin, 5-fluorouracil and hexachlorobenzene gave the lowest correlations with the first score vector of the PCA. The results presented are to be used to identify outliers that need to be further studied via the use of tissue-specific in vitro assays.

Identifiers
urn:nbn:se:umu:diva-11305 (URN)19025321 (PubMedID)
Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2018-06-09Bibliographically approved
Sjöström, M., Kolman, A., Clemedson, C. & Clothier, R. (2008). Estimation of human blood LC50 values for use in modeling of in vitro – in vivo data of the ACuteTox project. Toxicology in Vitro, 22(5), 1405-11
Open this publication in new window or tab >>Estimation of human blood LC50 values for use in modeling of in vitro – in vivo data of the ACuteTox project
2008 (English)In: Toxicology in Vitro, Vol. 22, no 5, p. 1405-11Article in journal (Refereed) Published
Abstract [en]

The main aim of the ACuteTox project, under EU 6th Framework programme, is to investigate whether animal toxicity tests for acute systemic toxicity could be replaced by a combination of alternative assays. Data for 97 reference chemicals was collected in the ACuteTox database (Acutoxbase), designed to handle in vitro and in vivo (human and animal) lodged data. The principal basis for demonstration of the applicability of in vitro tests is the in vitro–in vivo modeling, by using statistical correlation between in vitro IC50 molar values (the 50% inhibitory concentration for the endpoints measured) and human blood molar concentrations LC50 (50% lethal concentrations). The LC50 values were calculated from time-related sub-lethal and lethal blood concentrations determined from human acute poisoning cases. The 3T3 standard NRU assay (3T3 NRU) was chosen, among the various basal cytotoxicity assays, applied in the ACuteTox project, to demonstrate the applicability of the IC50/LC50 values for in vitro–in vivo modeling.

Linear regression analysis between IC50 (x) and LC50 (y) gave an explained variance R2 = 0.56 for the 67 reference chemicals, for which both sets of data were available. The results demonstrated usefulness of human LC50 values for in vitro–in vivo evaluation of the predictability of basal cytotoxicity assays for human acute systemic toxicity.

The R2 value of 0.56 shows, as in the MEIC study, that additional organ-specific and biokinetic tests are needed in order to improve the predictability.

Keywords
In vitro–in vivo modeling, Human LC50 values, IC50 values, 3T3 NRU, ACuteTox
Identifiers
urn:nbn:se:umu:diva-9642 (URN)10.1016/j.tiv.2008.04.017 (DOI)
Available from: 2008-06-16 Created: 2008-06-16 Last updated: 2018-06-09Bibliographically approved
Kinsner-Ovaskainen, A., Coecke, S., Sjöström, M., van Vliet, E. & Prieto, P. (2008). Optimisation and pre-validation of an in Vitro test strategy for predicting human acute toxicity: Progress of the “A-Cute-Tox” project. In: Proceedings of the Annual Congress of The British Toxicology Society. Elsevier Ireland Ltd.
Open this publication in new window or tab >>Optimisation and pre-validation of an in Vitro test strategy for predicting human acute toxicity: Progress of the “A-Cute-Tox” project
Show others...
2008 (English)In: Proceedings of the Annual Congress of The British Toxicology Society, Elsevier Ireland Ltd. , 2008Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Elsevier Ireland Ltd., 2008
Identifiers
urn:nbn:se:umu:diva-10962 (URN)10.1016/j.tox.2008.07.036 (DOI)
Note

Toxicology volume 253, issues 1-3, 20 November 2008, page 27; This issue includes: Proceedings of the Annual Congress of The British Toxicology Society

Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2018-06-09Bibliographically approved
Wiklund, S., Nilsson, D., Eriksson, L., Sjöström, M., Wold, S. & Faber, K. (2007). A randomization test for PLS component selection. Journal of Chemometrics, 21(10-11), 427-439
Open this publication in new window or tab >>A randomization test for PLS component selection
Show others...
2007 (English)In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 21, no 10-11, p. 427-439Article in journal (Refereed) Published
Abstract [en]

During the last two decades, a number of methods have been developed and evaluated for selecting the optimal number of components in a PLS model. In this paper, a new method is introduced that is based on a randomization test. The advantage of using a randomization test is that in contrast to cross validation (CV), it requires no exclusion of data, thus avoiding problems related to data exclusion, for example in designed experiments. The method is tested using simulated data sets for which the true dimensionality is clearly defined and also compared to regularly used methods for 10 real data sets. The randomization test works as a good statistical selection tool in combination with other selection rules. It also works as an indicator when the data require a pre-treatment.

Place, publisher, year, edition, pages
Chichester: Wiley & Sons, 2007
Keywords
randomization test, permutation test, component selection, factor selection, latent variable selection
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-2653 (URN)10.1002/cem.1086 (DOI)
Available from: 2007-10-19 Created: 2007-10-19 Last updated: 2018-06-09Bibliographically approved
Organisations

Search in DiVA

Show all publications