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Search Results: 1 - 10 of 208649 matches for " L. Bengtsson "
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High concentration but low biological activity of hepatocyte growth factor in patients with chronic renal failure  [PDF]
Johanna L?nn, Faisal Shahzad, Fredrik Uhlin, Torbj?rn Bengtsson, Gabriel Almroth, Fariba Nayeri
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.324068
Abstract: Hepatocyte growth factor (HGF) is a renotropic, antifibrotic and regenerative factor with cytoprotective effects that is produced by mesenchymal cells and shows high affinity to components of extra cellular matrix, such as heparan sulphate proteoglycan (HS-PG), in healthy. Patients with chronic renal failure (CRF) suffer from a chronic inflammatory disorder. In order to assess the underlying mechanisms for development of CRF we aimed to assess the amounts and affinity of HGF in this patient group. Elisa, western blot and surface plasmon resonance (SPR) were used to study HGF in blood samples, as well as in isolated neutrophils, in CRF patients compared to healthy controls. Patients with CRF showed higher HGF levels in serum (P < 0.0001), but decreased affinity to HSPG (P < 0.0001), compared to healthy controls. Addition of protease inhibitors decreased the difference between patients with CRF compared to healthy individuals. HGF with potent regenerative function during injury lacks affinity to HSPG in patients with CRF that may depend on production of proteases from activated immune cells. This information might be used to highlight underlying mechanisms for chronicity and leading to new strategies for treatment of chronic injuries.
Differences in the expression of hepatocyte growth factor in acute and chronic bowel inflammation—Implications for diagnosis?  [PDF]
Johanna L?nn, Sravya Nakka, Hans Olsson, Torbj?rn Bengtsson, Sven Almer, Fariba Nayeri
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.48A2006
Abstract:

Background: Hepatocyte growth factor (HGF) acts as an acute phase protein with regenerative properties. HGF is produced systemically and locally during inflammation but exhibits decreased binding affinity to heparan sulphate proteoglycan (HSPG)/glycosaminoglycan during chronic inflammation. We previously observed a high faecal concentration and binding affinity of HGF to HSPG during acute gastroenteritis. High faecal concentrations of calprotectin and HGF have been reported in chronic inflammatory bowel disease (IBD). Methods: Stool samples from patients with ulcerative colitis in remission (n = 11) or exacerbation (n = 5), microscopic colitis (n = 11), colon cancer (n = 6), or acute gastroenteritis caused by Clostridium difficile (n = 20), as well as healthy controls (n = 7), were analysed for the presence of HGF by ELISA, surface plasmon resonance, SDS-PAGE, and Western blot. Then in two patients with ulcerative colitis exacerbation and C. difficile infection, the expression of HGF and calprotectin was studied in colonic biopsies. Results: The faecal concentration of HGF was significantly higher in patients with ulcerative colitis compared to the other groups. The binding affinity to dextran was lower in all groups compared to acute inflammation. HGF receptor binding was similar across groups. In a patient with concomitant C. difficile infection and distal ulcerative colitis, HGF was highly expressed in the part of the bowel unaffected by ulcerative colitis, but no expression was found at the site of chronic inflammation. In the patient with total colitis the biopsies showed low expression of HGF. The areas with chronic inflammation exhibited infiltrating calprotectin-stained neutrophils. Conclusion: HGF is produced locally during inflammation of the bowel. The HGF produced during acute inflammation or exacerbations of chronic inflammation by the unaffected area shows binding affinity to glucosaminoglycans. Measuring HGF binding in faeces and biopsies may be a

Lookup Table Optimization for Sensor Linearization in Small Embedded Systems  [PDF]
Lars E. Bengtsson
Journal of Sensor Technology (JST) , 2012, DOI: 10.4236/jst.2012.24025
Abstract: This paper treats the problem of designing an optimal size for a lookup table used for sensor linearization. In small embedded systems the lookup table must be reduced to a minimum in order to reduce the memory footprint and intermediate table values are estimated by linear interpolation. Since interpolation introduces an estimation uncertainty that increases with the sparseness of the lookup table there is a trade-off between lookup table size and estimation precision. This work will present a theory for finding the minimum allowed size of a lookup table that does not affect the overall precision, i.e. the overall precision is determined by the lookup table entries’ precision, not by the interpolation error.
Teaching Anatomy in the Multimedia World—Using Digital Tools for Progressive Learning over Time  [PDF]
Marcus Granmo, Fredrik Bengtsson
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.611117
Abstract: In a cross-faculty project journalism students filmed anatomy briefings on a medical program. The material gave medical students free access to rehearse and repeat over time. The journalism students on their part practiced camera technique, directing and editing: It was an opportunity for students to help students. Following a quality evaluation of undergraduate studies at the Lund University medical faculty in 2011, we explored, developed, and implemented novel educational tools to meet students’ need in the multimedia world in which they operate. Incorporating complementary digital learning resources, in particular integration with mobile applications enabled us to meet students in their own world, thereby enhancing the learning process. We produced short video clips on specific anatomic themes, following the curriculum of the well-established anatomy course, and posted them online, allowing continuous rehearsal and repetition over time at a pace that suits individual students. Also, available to all semesters it provides free opportunities for repetition, reducing the risk of knowledge-loss between basic and clinical parts of the program. Besides the obvious benefits for students, the material gave teachers a clear view of the students’ curriculum. Thus, the material can be used for alternative, more interactive forms of examination. The paper describes the project, and the results from evaluations and integration with mobile technology.
Experimental determination of the respiratory tract deposition of diesel combustion particles in patients with chronic obstructive pulmonary disease
L?ndahl Jakob,Swietlicki Erik,Rissler Jenny,Bengtsson Agneta
Particle and Fibre Toxicology , 2012, DOI: 10.1186/1743-8977-9-30
Abstract: Background Air pollution, mainly from combustion, is one of the leading global health risk factors. A susceptible group is the more than 200 million people worldwide suffering from chronic obstructive pulmonary disease (COPD). There are few data on lung deposition of airborne particles in patients with COPD and none for combustion particles. Objectives To determine respiratory tract deposition of diesel combustion particles in patients with COPD during spontaneous breathing. Methods Ten COPD patients and seven healthy subjects inhaled diesel exhaust particles generated during idling and transient driving in an exposure chamber. The respiratory tract deposition of the particles was measured in the size range 10–500 nm during spontaneous breathing. Results The deposited dose rate increased with increasing severity of the disease. However, the deposition probability of the ultrafine combustion particles (< 100 nm) was decreased in COPD patients. The deposition probability was associated with both breathing parameters and lung function, but could be predicted only based on lung function. Conclusions The higher deposited dose rate of inhaled air pollution particles in COPD patients may be one of the factors contributing to their increased vulnerability. The strong correlations between lung function and particle deposition, especially in the size range of 20–30 nm, suggest that altered particle deposition could be used as an indicator respiratory disease.
Development of IDF-curves for tropical india by random cascade modeling
A. Rana,L. Bengtsson,J. Olsson,V. Jothiprakash
Hydrology and Earth System Sciences Discussions , 2013, DOI: 10.5194/hessd-10-4709-2013
Abstract: Efficient design of urban drainage systems is based on statistical analysis of past rainfall events at fine time scales. However, fine time scale rainfall data are usually lacking in many parts of the world. A possible way forward is to develop methods to derive fine time scale rain intensities from daily observations. This paper applied cascade-based disaggregation modeling for generation of fine time scale rainfall data for Mumbai, India from daily rainfall data. These data were disaggregated to 10-min values. The model was used to disaggregate daily data for the period 1951–2004 and develop intensity-duration-frequency (IDF) relationships. This disaggregation technique is commonly used assuming scale-invariance using constant parameters. For the Mumbai rains it was found better to use parameters dependent on time scale and rain volume. Very good agreement between modeled and observed disaggregation series was found for the time scales larger than 1/2 h for the 1/2-yr period when short term data were available. Although the parameters were allowed to change with time scale, the rain intensities of duration shorter than 1/2 h were overestimated. When IDF-curves had been established, they showed that the current design standard for Mumbai city, 25 mm h 1, has a return period of less than one year. Thus, annual recurring flooding problems in Mumbai appear evident.
Microarray image analysis: background estimation using quantile and morphological filters
Anders Bengtsson, Henrik Bengtsson
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-96
Abstract: This paper examines fundamental properties of rank and quantile filters, which include morphological filters at the extremes, with focus on their ability to estimate between-spot intensity levels. The bias and variance of these filter estimates are driven by the number of background pixels used and their distributions. A new rank-filter algorithm is implemented and compared to methods available in Spot by CSIRO and GenePix Pro by Axon Instruments. Spot's morphological opening has a mean bias between -47 and -248 compared to a bias between 2 and -2 for the rank filter and the variability of the morphological opening estimate is 3 times higher than for the rank filter. The mean bias of Spot's second method, morph.close.open, is between -5 and -16 and the variability is approximately the same as for morphological opening. The variability of GenePix Pro's region-based estimate is more than ten times higher than the variability of the rank-filter estimate and with slightly more bias. The large variability is because the size of the background window changes with spot size. To overcome this, a non-adaptive region-based method is implemented. Its bias and variability are comparable to that of the rank filter.The performance of more advanced rank filters is equal to the best region-based methods. However, in order to get unbiased estimates these filters have to be implemented with great care. The performance of morphological opening is in general poor with a substantial spatial-dependent bias.A microarray is defined as an ordered array of microscopic elements on a planar substrate which allows specific binding of genes or gene products [1]. For spotted cDNA microarrays double-stranded DNA sequences of length 500 to 2500 base pairs are printed on the substrate, which is usually a glass slide. The printed spots have a diameter in the range of some hundred μm and each spot consists of DNA specific to one gene. Oligonucleotide microarrays have probes with single-stranded oligon
The release of Hydrocarbons from softwood drying: Measurement and modeling
Bengtsson,Peter;
Maderas. Ciencia y tecnología , 2004, DOI: 10.4067/S0718-221X2004000200002
Abstract: the release of volatile organic compounds (voc) during the drying of norway spruce and scots pine was experimentally studied. heartwood and sapwood were separately dried at 60 oc. the flame ion detector (fid) was used to measure the total amount of hydrocarbons (thc) released during the drying process. a large difference of the emissions course between heartwood and sapwood were found. for heartwood, a release maximum of hydrocarbons followed by a typical negative exponential course was found. when drying sapwood, the released amount of hydrocarbons was evidently more fluctuating before reducing to zero. a model describing the release of hydrocarbons during the drying with only diffusion as transport mechanism was applied. the aim was to obtain a suitable explanation of the characteristic release behavior from sapwood and develop a model describing the process
The release of Hydrocarbons from softwood drying: Measurement and modeling
Peter Bengtsson
MADERAS : Ciencia y Tecnología , 2004,
Abstract: The release of volatile organic compounds (VOC) during the drying of Norway spruce and Scots pine was experimentally studied. Heartwood and sapwood were separately dried at 60 oC. The Flame Ion Detector (FID) was used to measure the total amount of hydrocarbons (THC) released during the drying process. A large difference of the emissions course between heartwood and sapwood were found. For heartwood, a release maximum of hydrocarbons followed by a typical negative exponential course was found. When drying sapwood, the released amount of hydrocarbons was evidently more fluctuating before reducing to zero. A model describing the release of hydrocarbons during the drying with only diffusion as transport mechanism was applied. The aim was to obtain a suitable explanation of the characteristic release behavior from sapwood and develop a model describing the process
What is the climate system able to do ‘on its own’?
Lennart Bengtsson
Tellus B , 2013, DOI: 10.3402/tellusb.v65i0.20189
Abstract: The climate of the Earth, like planetary climates in general, is broadly controlled by solar irradiation, planetary albedo and emissivity as well as its rotation rate and distribution of land (with its orography) and oceans. However, the majority of climate fluctuations that affect mankind are internal modes of the general circulation of the atmosphere and the oceans. Some of these modes, such as El Nino-Southern Oscillation (ENSO), are quasi-regular and have some longer-term predictive skill; others like the Arctic and Antarctic Oscillation are chaotic and generally unpredictable beyond a few weeks. Studies using general circulation models indicate that internal processes dominate the regional climate and that some like ENSO events have even distinct global signatures. This is one of the reasons why it is so difficult to separate internal climate processes from external ones caused, for example, by changes in greenhouse gases and solar irradiation. However, the accumulation of the warmest seasons during the latest two decades is lending strong support to the forcing of the greenhouse gases. As models are getting more comprehensive, they show a gradually broader range of internal processes including those on longer time scales, challenging the interpretation of the causes of past and present climate events further.
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