| 1. |
- Andersson, Anders, et al.
(författare)
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Effects of Tobacco Smoke on IL-16 in CD8+ Cells from Human Airways and Blood: a Key Role for Oxygen Free Radicals?
- 2011
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Ingår i: AJP - Lung cellular and molecular physiology. - : American Physiological Society. - 1522-1504. ; 300:1
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Tidskriftsartikel (refereegranskat)abstract
- Chronic exposure to tobacco smoke leads to an increase in the frequency of infections and in CD8(+) and CD4(+)cells as well as the CD4(+) chemo-attractant cytokine IL-16 in the airways. Here, we investigated whether tobacco smoke depletes intracellular IL-16 protein and inhibits de novo production of IL-16 in CD8(+) cells from human airways and blood, while at the same time increasing extracellular IL-16 and whether oxygen free radicals (OFR) are involved. Intracellular IL-16 protein in CD8(+) cells and mRNA in all cells was decreased in bronchoalveolar lavage (BAL) samples from chronic smokers. This was also the case in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro; in which oxidized proteins were markedly increased. Extracellular IL-16 protein was increased in cell-free BAL fluid from chronic smokers and in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro. This was not observed in occasional smokers after short-term exposure to tobacco smoke. A marker of activation (CD69) was slightly increased whereas other markers of key cellular functions (membrane integrity, apoptosis and proliferation) in human blood CD8(+) cells in vitro were negatively affected by water-soluble tobacco smoke components. An OFR scavenger prevented these effects whereas a protein synthesis inhibitor, a beta-adrenoceptor, a glucocorticoid receptor agonist, a phosphodiesterase, a calcineurin phosphatase and a caspase-3 inhibitor did not. In conclusion, tobacco smoke depletes preformed intracellular IL-16 protein, inhibits its de novo synthesis and distorts key cellular functions in human CD8(+) cells. OFR may play a key role in this context.
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| 2. |
- Andersson, Anders, et al.
(författare)
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Interleukin-16-producing NK cells and T-cells in the blood of tobacco smokers with and without COPD
- 2016
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Ingår i: International Journal of Chronic Obstructive Pulmonary Disease. - : Informa UK Limited. - 1178-2005. ; 11, s. 2245-2258
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Tidskriftsartikel (refereegranskat)abstract
- Background: Long-term exposure to tobacco smoke causes local inflammation in the airways that involves not only innate immune cells, including NK cells, but also adaptive immune cells such as cytotoxic (CD8(+)) and helper (CD4(+)) T-cells. We have previously demonstrated that long-term tobacco smoking increases extracellular concentration of the CD4(+)-recruiting cytokine interleukin (IL)-16 locally in the airways. Here, we hypothesized that tobacco smoking alters IL-16 biology at the systemic level and that this effect involves oxygen free radicals (OFR). Methods: We quantified extracellular IL-16 protein (ELISA) and intracellular IL-16 in NK cells, T-cells, B-cells, and monocytes (flow cytometry) in blood samples from long-term tobacco smokers with and without chronic obstructive pulmonary disease (COPD) and in never-smokers. NK cells from healthy blood donors were stimulated with water-soluble tobacco smoke components (cigarette smoke extract) with or without an OFR scavenger (glutathione) in vitro and followed by quantification of IL-16 protein. Results: The extracellular concentrations of IL-16 protein in blood did not display any substantial differences between groups. Notably, intracellular IL-16 protein was detected in all types of blood leukocytes. All long-term smokers displayed a decrease in this IL-16 among NK cells, irrespective of COPD status. Further, both NK and CD4(+) T-cell concentrations displayed a negative correlation with pack-years. Moreover, cigarette smoke extract caused release of IL-16 protein from NK cells in vitro, and this was not affected by glutathione, in contrast to the decrease in intracellular IL-16, which was prevented by this drug. Conclusion: Long-term exposure to tobacco smoke does not markedly alter extracellular concentrations of IL-16 protein in blood. However, it does decrease the intracellular IL-16 concentrations in blood NK cells, the latter effect involving OFR. Thus, long-term tobacco smoking exerts an impact at the systemic level that involves NK cells; innate immune cells that are critical for host defense against viruses and tumors-conditions that are over-represented among smokers.
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| 3. |
- Andersson, Ingemar, 1969
(författare)
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A Comparison of Combustion Temperature Models for Ionization Current Modeling in an SI Engine
- 2004
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Combustion temperature models for spark ignited engines are investigated in this work. The temperature models are evaluated as sub-models of a model for the thermal part of ionization current. Three different combustion temperature models were investigated; a single-zone model, a mixed two-zone model and an unmixed two-zone called a kernel-zone model. The combustion temperature is derived from cylinder pressure. The ionization current model structure also contain sub-models for formation of nitric oxide (NO) and its thermal ionization. The model output is compared to the measured ionization currents with respect to peak amplitude and position. Also, two models for NO formation are evaluated. The first is a fixed NO molar fraction model and the second is a reaction rate controlled NO formation model based on the extended Zeldovich reaction scheme. It is shown that a kernel-zone model shows better performance in both peak amplitude and peak position than both the single-zone model and the mixed two-zone model. Both NO formation models showed equal performance for high temperature combustion but the rate controlled NO model can make an important contribution in cases with lower combustion temperatures.
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| 4. |
- Andersson, Ingemar, 1969, et al.
(författare)
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A Parametric Model for Ionization Current in a Four Stroke SI Engine
- 2009
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Ingår i: Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME. - 0022-0434 .- 1528-9028. ; 131:2, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- A model for the thermal part of an ionization signal is presented that connects the ionization current to cylinder pressure and temperature in a spark ignited internal combustion engine. One strength of the model is that it after calibration has only two free parameters, burn angle and initial kernel temperature. By fitting the model to a measured ionization signal it is possible to estimate both cylinder pressure and temperature, where the pressure is estimated with good accuracy. The model approach is validated on engine data. Cylinder pressure and ionization current data was collected on a Saab 4-cylinder SI engine for a variation in ignition timing and air-fuel ratio.The main result is that the parameterized ionization current model can be used to estimating combustion properties as pressure, temperature and contentof nitric oxides based on measured ionization currents.The current status of the model is suitable for off-line analysis of ionization currents and cylinder pressure.This ionization current model not only describes the connection between the ionization current and the combustion process, it also offers new possibilities for EMS to control the internal combustion engine.
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| 5. |
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| 6. |
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| 7. |
- Andersson, Ingemar, 1969, et al.
(författare)
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Detection of Combustion Properties in a Diesel Engine using Block Mounted Accelerometers
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 2405-8963 .- 1474-6670. - 9783902823625 ; 19, s. 11866-11871
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Konferensbidrag (refereegranskat)abstract
- Engine block mounted accelerometers was used for estimating combustion phasing parameters for a heavy duty diesel engine. Several sensor locations were evaluated for its sensitivity to combustion related vibrations and mechanical noise.One sensor-cylinder combination was selected for the evaluation of a simple algorithm to detect 10% and 50% burned mass fraction. The algorithm uses the accumulated accelerometer vibration energy as a base for extracting the 10% and 50% points respectively.The results show that the angular positions for 10% and 50% burned mass fraction can be estimated with precisions of 1.5 and 3 CAD respectively. It is also concluded that the early part of the accelerometer signal has a significant influence from a mechanical noise source related to the start of injection.
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| 8. |
- Andersson, Ingemar, 1969, et al.
(författare)
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Evaluation of a Closed Loop Spark Advance Controller Based on a Torque Sensor
- 2008
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Ingår i: SAE Technical Papers. - : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- A closed loop spark advance control system was evaluated on a Volvo V70 5-cylinder spark ignited engine. The system utilises a crankshaft mounted torque sensor for combustion monitoring which provides individual cylinder combustion phasing information and enables individual cylinder spark advance control. The spark advance control system can compensate for changes in combustion operating conditions and hence limit the need for calibration. The spark advance control system was used in a mode of cylinder balancing where the control target is to keep the combustion phasing in all cylinders at a defined setpoint. This control law was evaluated in vehicle tests in an emission test chamber, running pre-defined driving cycles FTP72 and Highway Fuel Economy Test. Analysis shows that the combustion phasing was kept close to the selected setpoint during both tests and, hence, robustness in that sense was demonstrated. The torque ratio concept is used for combustion phasing monitoring based on crankshaft torque measurements. Analysis of the 50% torque ratio as a measure for combustion phasing shows that it is equivalent to 50% burned mass fraction.
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| 9. |
- Andersson, Ingemar, 1969
(författare)
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Ion Current and Torque Modeling for Combustion Engine Control
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Engine control development constantly requires more information about the combustion process, to meet present and future environmental regulations for vehicles. The demand for combustion monitoring and control from enginedevelopers drives the research in several parallel fields of technology to find the best and most cost effective sensor solution for each case. The ionization sensor and the crankshaft torque sensor are two sensor candidates which are investigated in this work. Their hardware is relatively cheap and robust but the development of methods for extracting important information content is subject to research.This thesis presents models that connects combustion properties of a spark ignited engine to the measured ionization and torque signals. The two sensor technologies are treated separately, but both with the same overall goal of solving the more interesting inverse problem, which isto derive combustion information from the measurements.The ionization current model consists of several sub-models which enables the estimation of cylinder pressure, combustion temperature and nitric oxide formation, based on the measured ionization current. One strength of the model is that after calibration, it has only two free parameters, burn angle and initial kernel temperature. Experimental validation of the model is done on the pressure estimation part, which shows good accuracy. The thesis develops a torque signal model that includes astrategy to linearize the crankshaft dynamics. A linear inverse algorithm is presented that separates the individualcylinder torque contributions from the measured signal.A new method, called the \emph{torque ratio concept}, is presented to provide means to estimate combustion properties from individual cylinder torque. The method contains a parameterized combustion model that captures burn duration and a measure for combustion phasing. The torque signal model and the torque ratio concept together providea scheme for estimating individual cylinder combustion phasing, based on torque measurements.The algorithms were implemented on a real-time platform for engine control. Closed-loop control of combustion phasing is demonstrated under the influence of unknown disturbances, e.g. varying fraction of the residual gas.
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