Many countries have implemented exposure limits for the concentration of ambient particular matter and do therefore have to monitor their concentration. This could be performed with TEOM monitors (Tapered Element Oscillating Microbalance-monitors) that contain a filter on which particles are collected. These filters are regularly exchanged for new ones. The aim of this study was to test the feasibility of collecting used filters from monitors at different locations and establishing a method to extract particles and then study them with respect to their ability to generate oxidants, their endotoxin content, and ability to activate inflammatory cells. Filters from nine geographically spread locations in Sweden were collected during a 21-month period by local technicians who then sent them to the laboratory where they were extracted and analyzed. The procedure to let local technicians perform the filter exchange and send used TEOM filters to the laboratory worked well. A method was established in which pyrogen-free water was used to extract particles that then were aliquoted and stored for later analysis. Particulate matter (PM10) from different locations showed both a considerable seasonal and spatial-dependent difference with respect to oxidative potential (oxidize glutathione), endotoxin content, and ability to activate blood monocytes to release interleukin-1β. This study shows that, instead of discarding TEOM filters, they can be collected and extracted so that particles that have been sampled in a standardized way could be analyzed with respect to variables that reflect their toxicity. This could be done at a low cost. In combination with information about the ambient particle concentration, such information could be helpful in the evaluation of differences in the risk of breathing air at various locations.

A simple moment of inspiration based on the American empiric psychologist Csíkszentmihalyi’s theory about optimal experience, internal motivation and flow was presented to medical students. The students, from the preclinical terms, were exposed to a movie showing a routine heart operation (coronary bypass) with comments during the film. The team presenting the film consisted of nurses in cardiothoracic and vascular anesthesia, a cardiothoracic surgeon, and a perfusionist. Questions from the students were answered by them. Thereafter, there was a panel discussion with junior specialists in cardiothoracic surgery and cardiology about the years after graduating.

The moment was evaluated using Touchpoint® and one single question: What is your opinion about the inspiration moment? Of the 77 participating students 65 (84%) answered that the moment was “very good” and 12 (16%) answered “good”.

These preliminary data suggest that the method may possibly be an adequate tool to increase internal motivation among preclinical semester medical students.

Introduction: student perception of problem-based learning (PBL) group tutorials was investigated at a Swedish University Medical College 27 years after the introduction of PBL into the curriculum.

Methods: a survey questionnaire comprising 43 questions answered on a Likert-type scale, together with one open question was used. The questionnaire was distributed to all 821 students taking part in the Linköping University medical program at the beginning of the Spring Term 2013. The results were subjected to explorative factor analysis, descriptive statistics and ANOVA. Responses to the open question where analyzed qualitatively by categorization.

Results: 84 per cent of the 821 students completed the survey. Four factors describing student perception were identified: 1) PBL as a method of learning; 2) the tutor’s role; 3) PBL, stress and feelings of insecurity; and 4) traditional teaching methods within the PBL curriculum. The Cronbach´s alpha value was 0,788 overall. Two hundred and seventy-six students answered the open question declaring that they would appreciate more precise aims and objectives, smaller tutorial groups, and more formal lectures.

Conclusions: the results of this study on PBL group tutorials, as seen from the student’s perspective, stress the importance of tutorial quality, tutor competence, tutorial group size and the quality and aims of the curriculum. Too much emphasis on the teacher’s research merits against the educational ones, and the inability to adapt to the needs and wishes of new generations of students seems a probable cause for the erosion of PBL.

Over the years a number of epidemiological studies have shown that PM from combustion sources such as motor vehicles contributes to respiratory and cardiovascular morbidity and mortality.Especially so do the ultra-fine particles (UFPs) with a diameter less than 0.1 micrometer.UFPs from combustion engines are capable to translocate over the alveolar–capillary barrier.  When nano-sized PM (nanoparticles, NP), which are small enough to enter the blood stream, do so they are likely to interact with plasma proteins and this protein-NP interaction will probably affect the fate of and the effects caused by the NPs in the human body. Here, by using a proteomic approach, we present results showing that several proteins indeed are associated to NPs that have in vitro been introduced to human blood plasma.

Airborne particulate matter is considered to be one of the environmental contributors to the mortality in cancer, respiratory, and cardiovascular diseases. For future preventive actions, it is of major concern to investigate the toxicity of defined groups of airborne particles and to clarify their pathways in biological tissues. To expand the knowledge beyond general inflammatory markers, this study examined the toxicoproteomic effects on human monocyte derived macrophages after exposure to wear particles generated from the interface of studded tires and a granite-containing pavement. As comparison, the effect of endotoxin was also investigated. The macrophage proteome was separated using two-dimensional gel electrophoresis. Detected proteins were quantified, and selected proteins were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Among analyzed proteins, seven were significantly decreased and three were increased by exposure to wear particles as compared to unexposed control cells. Endotoxin exposure resulted in significant changes in the expression of six proteins: four decreased and two increased. For example, macrophage capping protein was significantly increased after wear particle exposure only, whereas calgizzarin and galectin-3 were increased by both wear particle and endotoxin exposure. Overall, proteins associated with inflammatory response were increased and proteins involved in cellular functions such as redox balance, anti-inflammatory response, and glycolysis were decreased. Investigating the effects of characterized wear particles on human macrophages with a toxicoproteomic approach has shown to be useful in the search for more detailed information about specific pathways and possible biological markers.

The main interest in this article is students' involvement in assessment as a part of growth towards self-directedness in learning. In order to enhance students' development of autonomy in learning, a project involving 'older' students as peer examiners for 'younger' students was designed and carried out. Students in the sixth semester in a PBL-based Master's program of Medical Biology participated, together with faculty, as examiners of fifth-semester students. The examination and the assessment situation was carefully designed based on learning theories, empirical evidence and experiences underpinning student-centred learning, especially in the form of PBL used at the faculty. The project was evaluated and analysed in order to understand students' learning processes related to the responsibility for assessing peers. The situation of the peer examiners was interpreted based on their own experiences with statements from the students assessed and faculty involved in the assessment. Evaluations from six occasions, spring and fall, 2003-2005, were included in the study. The findings suggest that involving students in assessment as equal partners with faculty makes it is possible for students to apprehend the metacognitive competences needed to be responsible and autonomous in learning. The peer examiners experience motivation to learn about learning, they acquire tacit knowledge about assessment and they learn through being involved and trusted. The student-centred educational context, which requires responsibility throughout the programme, is recognized as very important.   

In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic is the main reason for high particle concentrations in busy street- and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM10) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, PIXE and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM10, respectively. The results show that in the road simulator, where resuspension is minimised, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consists almost entirely of minerals from the pavement stone material, but also that S is enriched for the sub-micron particles and that Zn is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM10 emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results implies that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties.

Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. These health risks are of increasing concern in society, and to protect public health, a clarification of the toxic properties of particles from different sources is of importance. Lately, wear particles generated from traffic have been recognized as a major contributing source to the overall particle load, especially in the Nordic countries where studded tires are used. The aim of this study was to further investigate and compare the ability to induce inflammatory mediators of different traffic-related wear particles collected from an urban street, a subway station, and studded tire-pavement wear. Inflammatory effects were measured as induction of nitric oxide (NO), IL-6, TNF-α, arachidonic acid (AA), and lipid peroxidation after exposure of the murine macrophage like cell line RAW 264.7. In addition, the redox potential of the particles was measured in a cell-free system. The results show that all particles tested induce IL-6, TNF-α, and NO, and those from the urban street were the most potent ones. In contrast, particles collected from a subway station were most potent to induce lipid peroxidation, A A release, and formation of ROS. Particles from studded tire-pavement wear, generated using a road simulator, were able to induce inflammatory cytokines, NO, lipid peroxidation, and ROS formation. Interestingly, particles generated from pavement containing granite as the main stone material were more potent than those generated from pavement containing quartzite as the main stone material.

The health effects of exposure to airborne particles are of increasing concern in society. In order to protect public health, a clarification of the toxic properties of particles from different sources is of importance. The aim of this study was to investigate and compare the genotoxicity and the ability to induce inflammatory mediators of nine different particle types from wood and pellets combustion, from tire–road wear and collected from an urban street and a subway station. The comet assay was used to assess genotoxicity after exposure of the human lung cell line A549. Inflammatory effects were measured as induction of IL-6, IL-8 and TNF-α after exposure of human macrophages. We found that all particles tested caused DNA damage and those from the subway caused more damage than the other particles (p < 0.001) likely due to redox-active iron. In contrast, particles collected from an urban street were most potent to induce inflammatory cytokines. Particles from tire–road wear collected using a road simulator were genotoxic and able to induce cytokines. Finally, more effective combustion of wood led to less emission of particles, but those emitted did not show less toxicity in this study.

Health risks associated with exposure to airborne paniculate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. Lately, wear particles generated from traffic have been recognized to be a major contributing source to the overall particle load, especially in the Nordic countries were studded tires are used. In this work, we investigated the inflammatory effect of PM₁₀ generated from the wear of studded tires on two different types of pavement. As comparison, we also investigated PM₁₀ from a traffic-intensive street, a subway station, and diesel exhaust particles (DEP). Human monocyte-derived macrophages, nasal epithelial cells (RPMI 2650), and bronchial epithelial cells (BEAS-2B) were exposed to the different types of particles, and the secretion of IL-6, IL-8, IL-10, and TNF-α into the culture medium was measured. The results show a significant release of cytokines from macrophages after exposure for all types of particles. When particles generated from asphalt/granite pavement were compared to asphalt/quartzite pavement, the granite pavement had a significantly higher capacity to induce the release of cytokines. The granite pavement particles induced cytokine release at the same magnitude as the street particles did, which was higher than what particles from both a subway station and DEP did. Exposure of epithelial cells to PM ₁₀ resulted in a significant increase of TNF-α secreted from BEAS-2B cells for all types of particles used (DEP was not tested), and the highest levels were induced by subway particles. None of the particle types were able to evoke detectable cytokine release from RPMI 2650 cells. The results indicate that PM₁₀ generated by the wear of studded tires on the street surface is a large contributor to the cytokine-releasing ability of particles in traffic-intensive areas and that the type of pavement used is important for the level of this contribution. Furthermore, the airway inflammatory potential of wear particles from tires and pavement might be of a greater magnitude than that of DEP.

In a road simulator study, a significant source of sub-micrometer fine particles produced by the road-tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15-50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15-700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7×1011 and 3.2×10 12 particles vehicle-1 km-1 at speeds of 50 and 70 km h-1. This corresponds to between 0.1-1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road-tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road-tire interface may be a significant contributor to particle emissions from ultraclean vehicles. © 2005 Elsevier Ltd. All rights reserved.

Phospholipase A₂ (PLA₂) is a superfamily of enzymes that may play a major role in airways inflammation. We investigated the effect of interferon-γ (IFN-γ) on the gene expression of 19 different PLA₂ types in human monocyte-derived macrophages and nasal epithelial cells (RPMI 2650). The cells were stimulated with IFN-γ for different lengths of time (up to 48 h), and the mRNA levels of the different PLA₂ types were determined by reverse transcriptase–PCR (RT-PCR) and normalized to those of the house-keeping gene, GAPDH. It appeared that IFN-γ clearly increased the expression of secretory PLA₂ IID (but not IIA) in macrophages, while both PLA₂ IID and IIA were upregulated in RPMI 2650 cells. Moreover, after 18 h, the mRNA levels of cytosolic PLA₂ IVA were 2–3 times higher in IFN-γ-stimulated macrophages than controls, while there was no such effect of IFN-γ in RPMI 2650 cells. Lipopolysaccharide (LPS) augmented the increased gene expression of PLA₂ IVA but decreased both the basal and the IFN-γ-induced PLA₂ IID mRNA expression in macrophages (but not in RPMI 2650 cells). The NF-κB inhibitor Pyrrolidine dithiocarbamate (PDTC) and the phoshatidylinositol 3-kinase (PI3K) inhibitor wortmannin were employed to get an insight into the mechanism behind these observations. Incubation of macrophages with PDTC had no effect on the LPS impairment of PLA₂ IID gene expression, but inhibited the LPS mediated activation of PLA₂ IVA. No significant effect was noted of PDTC on IFN-γ stimulation, while PI3K had no effect at all on any of the stimuli used. Furthermore, LPS (but not IFN-γ) increased the mRNA levels of the nuclear factor (NF)-κB inhibitors α and ξ in macrophages, but not in RPMI 2650 cells. These findings indicate that (a) the gene expression of secretory types PLA₂ IID and IIA in response to IFN-γ is much dependent on cell type, and (b) the regulation of PLA₂ type IID in human macrophages is clearly different from that of PLA₂ type IVA. (c) PLA₂ IVA is probably under control of both NF-κB and IFN-γ-responsive elements (GRE) or IFN-γ-activating sites (GAS). The possibility that PLA₂ IID is involved in cytokine-mediated inflammation in the nasal mucosa is inferred, as is the potential role of PLA₂ IID in the host defense against LPS-containing bacteria.

Phospholipase A₂ (PLA₂) is a family of enzymes that play different role(s) in inflammation, but their importance in seasonal allergic rhinitis (SAR) has not been clarified. Here, we determined the levels of messenger ribonucleic acid (mRNA) for different PLA₂ types in the nasal mucosa of SAR patients (n=6) and healthy controls (n=5). Nasal brush samples were taken both during pollen season, when the symptoms of the patients were severe, and off-season, when the patients were free of symptoms. We found that PLA₂ IB, IIA, IID,IIE, IIF III, IVA, IVB, IVC, VIA, VIB, VIIA, VIIB, VIIIA, VIIIB, X, XII and XIII were all expressed in each subject at both occasions. The mRNA levels of PLA₂ VIIA (platelet-activating factor (PAF) acetylhydrolase) were lower in SAR patients than controls, both during pollen season (p = 0.03) and off season (p = 0.03). These findings demonstrate that a large number of PLA₂ types are expressed in the nasal mucosa, regardless of whether there is ongoing allergic inflammation or not. The observation that PAF acetylhydrolase mRNA expression in the nasal mucosa is lower in SAR patients than in healthy subjects suggests the possibility that impaired ability to inactivate PAF might be of importance in SAR. Further studies are required to clarify whether the decreased PAF acetylhydrolase mRNA expression in SAR is accompanied by decreased enzyme activity and whether aberrations in PAF acetylhydrolase are present in infectious rhinitis patients as well.

Clara cell 10-kDa protein (CC10) is a major component of bronchoalveolar lavage fluid and is suggested to be a natural regulator of airway inflammation, possibly through its effects on theproin-flammatory enzyme(s), phospholipase A2. We examined the effect of recombinant human (rh) CC10 on endotoxin-induced airway contraction and cytokine release in isolated perfused rat lungs. We found that rhCC10 added to the lung perfusate abolished the endotoxin-induced airway contraction, and that it inhibited both the release of interleukin-1▀ and interleukin-6 into the lung perfusate and the release of tumor necrosis factors, into the pulmonary lavage fluid. By contrast, the levels of interferon-? were unaffected by CC10 administration. Rutin, a phospholipase A2 inhibitor, and N?-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, also attenuated the contraction induced by endotoxin. These findings demonstrate that rhCC10 inhibits endotoxin-induced airway contraction and the release of proinflammatory cytokines (interleukin-1▀, interleukin-6, and tumor necrosis factor-a) in isolated perfused rat lungs. The results also indicate that phospholipase A2 and nitric oxide are involved in the airway contraction in this model, possibly through their influence on the production of eicosanoids.

Phospholipase A₂ (PLA₂) is a growing family of enzymes that may play a major role in inflammation. We investigated the effect of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) on the gene expression of 19 different PLA₂ types (IB, IIA, IID, IIE, IIF, III, IVA, IVB, IVC, V, VIA, VIB, VIIA, VIIB, VIIIA, VIIIB, X, XII, and XIII) in human bronchoepithelial (BEAS-2B) and nasal epithelial (RPMI 2650) cells. The cells were stimulated with TNF-α or IFN-γ for different lengths of time (1, 4, 18, and 48 h), and the mRNA levels of the different PLA₂ types were determined by reverse transcriptase-PCR (RT-PCR) and normalized to those of the housekeeping gene, GAPDH. In both cell lines, TNF-α increased the expression of PLA₂ IVA and IVC, and IFN-γ increased the expression of PLA₂ IIA and IID. No influence on the gene expression of PLA₂-activating protein (PLAP) was noted on cytokine stimulation. These findings indicate that TNF-α and IFN-γ induce gene expression of two novel cytosolic and secretory PLA₂ types (IVC and IID, respectively) in human airway epithelial cells. The possibility that these PLA₂ types are involved in cytokine-mediated inflammation in the respiratory tract is inferred.

Phospholipase A₂ (PLA₂) is a family of enzymes thought to play a key role in inflammation by releasing arachidonic acid for the synthesis of eicosanoids and lysophospholipid for the synthesis of platelet-activating factor. However, the precise contribution of different PLA₂ types to the formation of inflammatory lipid mediators in the upper airways is not known and the expression of different PLA₂ genes in the human nasal mucosa has not been examined.

This study therefore investigated the occurrence of messenger ribonucleic acids (mRNAs) for different PLA₂ forms (IB, IIA, IID, IIE, III, IVA, IVB, IVC, V, VI, VII, X, acid calcium-independent (aiPLA₂), and calcium-independent membrane bound PLA₂, (iPLA₂-2)) in the nasal mucosa of five healthy human subjects.

Using reversed transcription-polymerase chain reaction (RT-PCR) techniques it was found that all these PLA₂ types except PLA₂ V were expressed in all subjects, whereas PLA₂ V was detected in only one individual on one single occasion. The relative abundance of the different PLA₂ transcripts were aiPLA₂>X≈IVA>IIA≈IIE≈IVB≈VI>IB≈IID≈III≈IVC≈VII≈iPLA₂-2. To further quantify the mRNA-expression of PLA₂ X, IVA and IIA, the samples were reanalysed with a quantitative PCR-technique utilizing competitive deoxyribonucleic acid (DNA) mimics as references. The amounts of PLA₂ X, IVA and IIA mRNA were then estimated to 0.9±0.2, 1.1±0.7, and 0.0025±0.0021 amol (mean±se), respectively, confirming the relative abundance of these PLA₂ transcripts and indicating that the recently described PLA₂ X form is relatively strongly expressed.

These findings demonstrate that a large number of PLA₂ types are expressed in the normal human nasal mucosa. Moreover, this investigation demonstrates, for the first time, the presence of the newly discovered phospholipase A₂ forms IID, IIE, III, IVB, IVC, X and calcium-independent membrane bound phospholipase A₂ in the human nasal mucosa and raises the possibility that one or several of these may be involved in inflammatory reactions in the nose.

Isolated perfused rat lungs (IPRLs) were used to study mechanisms andmediators of lung injury due to (i) ischemia-reperfusion (IR) and (ii) endotoxin. To investigate the role of polymorphonuclear neutrophils (PMNs) in IR injury, PMNs were added to the perfusate of IPRLs subjected to IR. PMNs did not contribute to the injury as assessed by albumin leak indices. Addition of erythrocytes or catalase attenuated the injury, indicating that IR injury is dependent on a non-PMN source of toxic 02 metabolites. Moreover, increased levels of 6-keto-PGE1o: and tromboxane B2 were found in the perfusate and cyclooxygenase and thromboxane synthase inhibitors (indomethacin and U 63557A) reduced the injury, suggesting that cyclooxygenase metabolites of arachidonic acid are involved in IR lung injury.

To study PMN-dependent injury in IPRLs, phorbol ester-activated PMNs were added to the perfusate in the presence of Iloprost, a long-acting prostacyclin analog. Iloprost attenuated the lung injury and decreased PMN adherence to endothelial monolayers in vitro, indicating that prostacyclin is an important regulator of PMN-dependent injury in the lung. PMN-dependent lung injury was further explored by adding calcium ionophore-activatcd PMNs prestimulated with endotoxin to the perfusate and studying the increases in pulmonary arterial pressure and capillary permeability. Both these effects were attenuated by the Ginkgo biloba-derived platelet-activating factor (PAF) antagonist, BN 52021, suggesting that endotoxin-stimulated, calcium ionophore (A 23187)activated PMNs exert important parts of their pro-inflammatory action via generation of PAF. Furthermore, addition of endotoxin to the perfusate of IPRLs caused elevated levels of group-11 phospholipase A2 (PLAz), tumor necrosis factor alpha (TNF-o:) and interleukin-1 beta (Il-1~) mRNA in the lung tissue and release of PLA2 and TNF-o: activity into the perfusate. Increased TNF-a m RNA levels and increased TNF-o: activity release were also found in alveolar macrophages exposed in vitro to asbestos as well as man made mineral fibers. In conclusion, these observations illustrate the importance of PLA2 - related mediators in inflammatory lung injury and demonstrate that neutrophils are involved in some but not necessary for all types of lung injury to occur.

Phospholipase A₂ (PLA₂) is a superfamily of enzymes that may play a major role in airways inflammation. We investigated the gene expression of 20 different PLA₂ types in nasal epithelial cells (RPMI 2650) before and after incubation with cell growth medium from human monocyte-derived macrophages exposed to lipopolysaccharide (LPS) or ß-1,3-D-glucan (ßG). The macropbages were exposed to LPS (10 µ/ml) or ßG (500 µg/ml) for 48 hours and the mRNA levels of the different PLA₂ types in RPMI 2650 cells were determined after incubation for 18 hours using reverse transcriptase-PCR (RT-PCR). It appeared that the mRNA levels of PLA₂ type IVC were significantly increased after incubation, both with medium from LPS-exposed and ßG-exposed macrophages. In both cases, the increased PLA₂ IVA mRNA expression was abolished by TNF-α antibodies and by the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC). There were no significant alterations in the mRNA levels of the other PLA₂ types, including PLA₂ IVA. These findings indicate that both LPS- and ßG-activated macrophages can induce the gene expression of PLA₂ IVC in nasal epithelial cells, and that this upregulation is mediated through TNF-α and under NF-κB control. Further studies are required to clarify whether these mechanisms may operate to cause inflammation in the nasal mucosa in vivo.