The potential of bike desks to reduce sedentary time in the office: a mixed-method study.

OBJECTIVES: To investigate the use of bike desks in an office setting and office workers' experiences of bike desks. STUDY DESIGN: Mixed-method study; quantitative data of cycling desk use in combination with qualitative data of users' experience were obtained via questionnaires. METHODS: Bike desks were provided in an office setting during a five-month period. The amount of cycled time, distance and the cycling intensity were registered. At the end of the intervention period, participants filled out a questionnaire about their experiences of cycling desks in the office. RESULTS: Participants cycled for approximately 98 min/week. Most participants were very positive about their bike desk experience and almost all of them would continue using them. About one third of the participants experienced a positive effect on attention and work performance and for about two thirds it positively influenced their motivation during work. Furthermore, about half of the participants felt more energetic, more self-confident and perceived a positive effect on their health and lifestyle. CONCLUSIONS: Providing bike desks in an office reduces office workers sedentary time. Furthermore, people experienced positive effects on several personal and work-related parameters. Therefore, providing bike desks in office settings seems to be a promising means to reduce sedentary time.

The use of cycling workstations in public places - an observational study.

OBJECTIVES: To determine the use of cycling workstations in public places; how long are they used, who uses them, and why do people use them. STUDY DESIGN: Mixed methods study; observations in combination with questionnaires. METHODS: Cycling desks with a charging feature (We-bike) at Brussels National Airport and Brussels South railway station were observed. Data about the number of users, time spent using the workstation, cycling and charging behaviour, were collected by observation. Data about sex, age, body mass index (BMI) and the reason of the use, were obtained via a survey. RESULTS: Approximately three people per hour cycled on the workstation. Mean (SD) cycling time was 15.2 (11.9) minutes and mean (SD) cycling intensity was 2.11 (1.16) on the modified Borg scale. 88% of the users charged a device. About two-thirds of the observed people were male and the majority was between 26 and 45 years old (44%). The average BMI (SD) of the surveyed participants was 24.0 (3.1) kg/m(2), with 26.1% of the participants being overweight. People used the desks because they thought it was fun, relaxing, a good distraction, healthy, good for maintaining shape and/or eco-friendly. However, the majority of the participants (83%) used it because of the charging feature and only one-third of the people would also use the desk if a charging feature was not available. CONCLUSIONS: Cycling desks at public places are used by approximately three people per hour. The charging feature is an important motivating factor as only one-third of the people would use the cycling workstation if there would not be a charging feature. As this easy-to-use machine brings about a decrease in sedentary behaviour and an increase in energy expenditure, the availability at places accessible to everyone, could contribute to a less sedentary society and could thus contribute to the prevention of diseases and mental problems related to prolonged sitting.

Health benefits of cycling: a systematic review.

The purpose of this study was to update the evidence on the health benefits of cycling. A systematic review of the literature resulted in 16 cycling-specific studies. Cross-sectional and longitudinal studies showed a clear positive relationship between cycling and cardiorespiratory fitness in youths. Prospective observational studies demonstrated a strong inverse relationship between commuter cycling and all-cause mortality, cancer mortality, and cancer morbidity among middle-aged to elderly subjects. Intervention studies among working-age adults indicated consistent improvements in cardiovascular fitness and some improvements in cardiovascular risk factors due to commuting cycling. Six studies showed a consistent positive dose-response gradient between the amount of cycling and the health benefits. Systematic assessment of the quality of the studies showed most of them to be of moderate to high quality. According to standard criteria used primarily for the assessment of clinical studies, the strength of this evidence was strong for fitness benefits, moderate for benefits in cardiovascular risk factors, and inconclusive for all-cause mortality, coronary heart disease morbidity and mortality, cancer risk, and overweight and obesity. While more intervention research is needed to build a solid knowledge base of the health benefits of cycling, the existing evidence reinforces the current efforts to promote cycling as an important contributor for better population health.

Commuter cycling: effect on physical performance in untrained men and women in Flanders: minimum dose to improve indexes of fitness.

The purpose was to examine (1) the effect of cycling to work on physical performance; (2) the minimum weekly energy expenditure needed for fitness improvement based on the dose-response relationship between total caloric expenditure and fitness changes. Healthy, untrained men and women, who did not cycle to work, participated in a 1-year intervention study. Sixty-five subjects were asked to cycle to work at least three times a week. Fifteen subjects were asked not to change their living habits. All measurements were performed on three consecutive occasions, with 6 months in between. Maximal external power (P(max)), heart rate, respiratory exchange ratio and peak oxygen uptake (VO(2peak)) were assessed. Cycling characteristics and leisure time physical activities were reported in a dairy. A significant change over time between both groups was seen for VO(2peak) (/kg) in the total group and the women and for P(max) in the total group. Correlations were found between VO(2peak) (/kg) (r>/=0.40) and kcal/week and min/week. Preliminary results indicate that the minimum expended energy needed for the improvement of indexes of fitness is higher for men compared with women.

Cycling to work: influence on indexes of health in untrained men and women in Flanders. Coronary heart disease and quality of life.

The purpose of this study was to examine if a 1-year lifestyle intervention study (cycling to work) has an influence on coronary heart disease (CHD) risk factors and health-related quality of life, in previously untrained healthy adults. Healthy, untrained men and women, who did not cycle to work, participated in an intervention study. Sixty-five subjects (intervention group: IG) were asked to cycle to work at least 3 times a week and 15 controls (CG) were asked not to change their living habits. All measurements were performed on 3 consecutive occasions, with 6 months in between. Physical performance, venous blood samples, blood pressure (BP), and the SF-36 Health Status Survey were assessed. Cycling characteristics and leisure-time physical activities were reported in a dairy. Total cholesterol (TC), LDL, TC/HDL and diastolic BP decreased and HDL increased significantly in the IG. TC and LDL decreased significantly in the CG. Vitality for the total group and physical functioning for women significantly changed over time between IG and CG in the first 6 months. These results show that cycling to work has a positive influence on CHD risk factors and is likely to improve the health-related quality of life in previously untrained healthy adults.

Determining the intensity and energy expenditure during commuter cycling.

OBJECTIVES: To determine the intensity and energy expenditure during commuter cycling, and to investigate whether cycling to work at a self-chosen intensity corresponds to recommendations of the Centers for Disease Control and Prevention (CDC) and American College of Sports Medicine (ACSM) for health improvement and ACSM recommendations for fitness improvement. METHODS: 18 healthy, untrained middle-aged people, who did not cycle to work, underwent two maximal exercise tests (MT and MT2) in order to measure their maximal heart rate and oxygen consumption (VO(2)). MT2 was performed 24 weeks after MT. Participants were asked to cycle at least three times a week to their workplace over a one-way minimum distance of 2 km. Data on cycling were recorded in a diary. 12 weeks after MT, a field test was conducted, where participants had to cycle to or from their workplace. The same measurements were taken as during MT as markers of exercise intensity. Metabolic equivalents (METs) and energy expenditure were calculated. RESULTS: The intensity during the field test was >75% of their maximal aerobic capacity. The mean (SD) MET value was 6.8 (1.9). The energy expenditure during the field test was 220 (115) kcal or 540 (139) kcal/h and 1539 (892) kcal/week. Men consumed significantly (p<0.01) more energy per hour than women. CONCLUSION: Commuter cycling at a self-selected intensity meets the CDC and ACSM recommendations for health improvement and the ACSM recommendations for improvement of cardiorespiratory fitness. However, as the participants cycled faster during the field test than during daily cycling, the results should be interpreted with caution.

Comparison of physical chemical properties of llama VHH antibody fragments and mouse monoclonal antibodies.

Antigen specific llama VHH antibody fragments were compared to antigen specific mouse monoclonal antibodies with respect to specificity, affinity and stability. The llama VHH antibody fragments and the mouse monoclonal antibodies investigated were shown to be highly specific for the protein antigen hCG or the hapten antigen RR-6. The affinity of the interaction between monovalent llama VHH antibody fragments and their antigen is close to the nanomolar range, similar to the bivalent mouse monoclonal antibodies studied. Llama VHH antibody fragments are similar to mouse monoclonal antibodies with respect to antigen binding in the presence of ammonium thiocyanate and ethanol. The results show that relative to antigen specific mouse monoclonal antibodies, antigen specific llama VHH fragments are extremely temperature stable. Two out of six llama VHHs are able to bind antigen specifically at temperatures as high as 90 degrees C, whereas four out of four mouse monoclonal antibodies are not functional at this temperature. Together with the finding that llama VHH fragments can be produced at high yield in Saccharomyces cerevisiae, these findings indicate that in the near future antigen specific llama VHH fragments can be used in for antibodies unexpected products and processes.

Llama heavy-chain V regions consist of at least four distinct subfamilies revealing novel sequence features.

In addition to conventional antibodies (Abs), camelids possess Abs consisting of only heavy chains. The variable domain of such a heavy-chain Ab (VHH) is fully capable of antigen (Ag) binding. Earlier analysis of 47 VHHs showed sequence features unique to VHH domains. These include the presence of characteristic amino acid substitutions in positions which, in conventional VH domains are involved in interdomain interactions, and the presence of a long third complementarity-determining region (CDR3) which is frequently constrained by an interloop disulphide bond. Here, we describe a large (152) set of Lama glama VHH cDNAs. Based on amino acid sequence similarity, these and other published camelid VHHs were classified into four subfamilies. Three subfamilies are absent in dromedaries, which have been the primary source of VHHs thus far. Comparison of these subfamilies to conventional VH regions reveals new features characteristic of VHHs and shows that many features earlier regarded as characteristic of VHHs in general are actually subfamily specific. A long CDR3 with a concomitant putative additional disulphide bond is only observed in two VHH subfamilies. Furthermore, we identified new VHH-characteristic residues at positions forming interdomain sites in conventional VH domains. The VHH subfamilies also differ from each other and conventional VH domains in the canonical structure of CDR1 and CDR2, mean CDR3 length, and amino acid residue variability. Since different VHH-characteristic residues are observed in all four subfamilies, these subfamilies must have evolved independently from classical VH domains.

T-cell receptor V beta-family usage in primary cutaneous and primary nodal T-cell non-Hodgkin's lymphomas.

To evaluate whether the expression of T-cell receptor (TCR) V beta families in eight cases of malignant T-cell lymphomas took place in a preferential manner, we analyzed four cases of mycosis fungoides (MF), the most common form of primary cutaneous T-cell non-Hodgkin's lymphomas (NHL), and four cases of primary nodal T-cell NHL. The usage of V beta families in T-cell populations was investigated on mRNA that was transcribed to cDNA using a C beta primer and reverse transcriptase. Subsequently, the specific usage of the families was analyzed by polymerase chain reaction (PCR) using combinations of the selected C beta-oligonucleotide primer and one of the family-specific V beta primers. Peripheral blood lymphocytes from four healthy volunteers and 1 "reactive" lymph node served as a control and expressed all 20 V beta families tested for. In T-cell lines, with restricted V beta expression, and in three patients with advanced MF, only one or two V beta families were expressed at the mRNA level. In an early MF lesion this monoclonal expression was absent: several V beta families were expressed with a weak intensity. This may indicate either a polyclonal origin of MF, or that too few monoclonal neoplastic cells were present in the tissue specimen. In the four nodal T-cell NHL, only one family could be clearly distinguished, whereas some of the other V beta families showed only a weak expression. These latter families represent the reactive T-cell component in the nodal T-cell NHL. Both in nodal T-cell NHL and in MF there was no preferential expression of a particular V beta family. There was a good correlation between PCR data and the expression of V beta-family protein products observed by immunohistochemistry on tissue sections of the T-cell lymphomas. All T-cell lines, three cases of MF, and three cases of nodal T-cell NHL showed a rearrangement of the TCR beta chain on DNA level.

Induction of immune responses and molecular cloning of the heavy chain antibody repertoire of Lama glama.

Functional heavy chain immunoglobulins have, so far, only been found in camels and llamas. Antigen-specific fragments of these heavy chain IgGs (V(HH)) are of great interest in biotechnology because they are very stable and can be produced at high level by the yeast Saccharomyces cerevisiae. The work described in this paper was conducted to determine whether llamas (Lama glama) are a practical source of antigen-specific V(HH) fragments. Llamas were immunised with various types of antigens and the antibody responses were examined during the course of immunisation. Both, conventional and heavy chain IgG antibodies were produced in response to each of the antigens. The heavy chain IgG repertoire displayed a recognition pattern different to that of conventional llama IgGs, resulting in the expansion of the accessible epitope repertoire. Llamas have a lower proportion of heavy chain IgG antibodies in their serum than have camels. To enable the specific and efficient isolation of V(HH) genes from peripheral blood B-cells, the long and short-hinge sequences of Lama glama heavy chain IgGs were determined, revealing the presence of a novel subclass of short-hinge heavy chain IgG. Long and short-hinge specific PCR primers were designed to be used in the construction of llama V(HH) libraries. We conclude that, using the techniques described, antigen-specific V(HH) antibody fragments are readily accessible from the llama, thus providing highly valuable binding molecules for a variety of applications.

Direct assessment of junctional diversity in rearranged T cell receptor beta chain encoding genes by combined heteroduplex and single strand conformation polymorphism (SSCP) analysis.

In order to define the extent of T cell heterogeneity and clonality, unique DNA sequences in the junctional region in rearranged T cell receptor (TcR) genes can be studied. For this purpose we have adapted a non-denaturing nucleic acid gel electrophoresis procedure to detect TcR junctional diversity. Detection of junctional diversity is based upon electrophoretic separation of single stranded (ss) and double stranded (ds) DNA molecules via mobility shifts due to nucleotide sequence polymorphism. To examine the capacity of this nucleic acid gel electrophoresis procedure to detect nucleotide sequence polymorphism in the CDR 3 region within TcR V beta gene family sequences polymerase chain reaction (PCR) amplified TcR V beta 5.1/5.4 and V beta 14 cDNA sequences were analyzed. The results of this study showed that (1) the single strand conformation polymorphism (SSCP) procedure has a low capacity to discriminate between diverse TcR V beta cDNA sequences due to comigration of the ssDNA molecules, which results in an underestimation of the heterogeneity in a given T cell population; (2) comigrating ssDNA and/or dsDNA (homoduplex) molecules can be separated by the formation of heteroduplex molecules; these heteroduplex molecules provide essential additional information on the degree of nucleotide sequence polymorphism in the CDR 3 region within the TcR V beta cDNA sequences; (3) the double strand conformation polymorphism (DSCP) procedure provides a fast and reliable procedure to detect junctional diversity within the sequences tested. Using DSCP a more detailed assessment of amplified TcR V beta cDNA sequences can be obtained as compared with SSCP analysis only. Data obtained by gel analysis were very similar to those obtained by conventional bacterial cloning and DNA sequencing procedures on the corresponding cDNA clones. In conclusion, this new gel electrophoresis procedure allows a direct assessment of the extent of T cell heterogeneity and clonality by screening junctional diversity in TcR chain encoding sequences in clinical conditions with (oligo)clonal expansion of T lymphocytes.

Denaturing and non-denaturing gel electrophoresis as methods for the detection of junctional diversity in rearranged T cell receptor sequences.

Two nucleic acid gel electrophoresis techniques were tested as a possible tool for analyzing junctional diversity in rearranged T cell receptor (TcR) sequences in order to define the extent of T cell heterogeneity. For this purpose denaturing gradient gel electrophoresis (DGGE) as well as non-denaturing gel electrophoresis (nDGE) techniques have been studied. Detection of junctional diversity is based on mobility shifts, caused by nucleotide sequence polymorphism, of polymerase chain reaction amplified rearranged TcR sequences. DGGE as well as nDGE procedures are suitable for the detection of junctional diversity in TcR V gene family sequences based on sequence dependent separation. Compared to DGGE, nDGE of DNA is a relatively simple and rapid procedure, with a high separation potential. nDGE permits separation of double stranded (homoduplexes) and/or single stranded DNA molecules of the majority of TcR chain encoding sequences. Formation and detection of unique heteroduplex molecules combined with single stranded DNA molecule analysis in nDGE permits the recognition of the remaining sequences, thus providing additional information on the degree of T cell heterogeneity. In conclusion, these nucleic acid gel electrophoresis techniques allow a direct assessment of the heterogeneity and clonality of T cell populations by the detection of junctional diversity in TcR chain encoding sequences. This analysis can be performed without the need of cell propagation and/or cellular cloning procedures, thereby eliminating the risk of introducing technical artefacts.

Sequelae in long-term survivors of small cell lung cancer.

PURPOSE: Central nervous system (CNS) effects of chemotherapy and prophylactic cranial irradiation (PCI) are studied in long-term small cell lung cancer (SCLC) survivors. The exact significance and pathogenesis of the neurotoxicity is still unknown, as studies on this subject lack sufficient patient numbers and are performed in an extremely varied manner. METHODS AND MATERIALS: Fifty-nine survivors (> 2 years from diagnosis) were examined neurologically and neuropsychologically, and underwent a cranial computer tomography (CT) scan or magnetic resonance (MR). Eight patients were excluded from further analysis for various reasons (not SCLC-related CNS disease, n = 6; no chemotherapy nor PCI treatment, n = 2). The remaining 51 patients were divided into three groups; group 1 = chemotherapy alone (n = 21), group 2 = sequential PCI (n = 19), and group 3 = concurrent or sandwiched PCI (n = 11). Groups were neuropsychologically compared in matched controls. RESULTS: Performance status did not differ significantly between various treatment groups; all patients remained ambulatory and capable of self-care. Mental impairment (n = 20), motor abnormalities (n = 9), and visual complaints (n = 1), were found in five patients in group 1 (24%), eight patients in group 2 (42%), and eight patients in group 3 (73%). Analysis of brain atrophy revealed no significant results; however, white matter abnormalities were found more frequently in group 3. Neuropsychologically no significant group differences existed, although interference sensitivity and difficulties with divided attention tended to occur more frequently in patients treated with PCI. Mean neuropsychometric results of treatment groups were significantly worse than those of matched controls. CONCLUSIONS: Although more intensively treated patients showed more neurologic impairment and patients in group 3 had more white matter abnormalities, there was no statistic evidence for additional neurotoxicity of PCI. Marked neuropsychometric differences between patients and matched controls may indicate that cognitive impairment is partly disease related, probably due to emotional distress and deteriorated physical condition.

Changes in the intestinal lymphoid compartment throughout life: implications for the local generation of intestinal T cells.

The intestinal lymphoid compartment has a rather stable composition throughout life. However, both during early neonatal development and at high age unique cell populations can be recognized at distinct sites in the intestinal tissue. Directly after birth all intestinal CD3+ cells are found in the lamina propria. At this time the epithelium does not contain T cells. These CD3+ lamina propria lymphocytes co-express both TCR beta and TCR delta chains, probably reflecting the expression of a TCR beta delta heterodimer on the cell surface. Cells with this particular phenotype are present in comparable numbers in the lamina propria of both neonatal euthymic and athymic mice, indicating the thymus-independent nature of these cells. During aging the frequency of TCR alpha beta+ CD8 alpha alpha+ intestinal T cells increases. These cells are also considered to be thymus-independent. The appearance of high numbers of CD4+ CD8 alpha alpha+ intestinal T cells in aged mice is even more striking. It is postulated that the neonatal TCR beta delta+ cells, and probably also the CD4+ CD8 alpha alpha+ cells as found in old mice, are intermediates in the extrathymic differentiation pathway of TCR alpha beta+ CD8 alpha alpha+ intestinal T cells.

Constitutive expression of Ly-6.A2 on murine keratinocytes and inducible expression on TCR gamma delta+ dendritic epidermal T cells.

We investigated the expression of Ly-6.A2 on isolated murine epidermal cells by flow cytometry. Ly-6.A2 was expressed on 61% of keratinocytes and 6% of dendritic epidermal T cells of C57BL mice. Phosphatidylinositol-specific phospholipase C removed Ly-6.A2, indicating that the antigen is anchored to the keratinocyte membrane via a glycosyl-phosphatidylinositol anchor similar to its attachment to the membrane of lymphocytes. Induction of dermatitis by topical application of PMA increased the expression of Ly-6.A2 on TCR gamma delta+ dendritic epidermal T cells and did not change its expression on keratinocytes. The increased expression of Ly-6.A2 on dendritic epidermal T cells was transient and reached a peak at 4 days after application of PMA, when 55% of the cells were positive.

Improved production and function of llama heavy chain antibody fragments by molecular evolution.

The aim of this study was to improve production level of llama heavy chain antibody fragments (V(HH)) in Saccharomyces cerevisiae while retaining functional characteristics. For this purpose, the DNA shuffling technique was used on llama V(HH) fragments specific for the azo-dye reactive red-6. In the DNA shuffling process, three parental llama V(HH) with high amino acid sequence identity with significant differences in production and functional characteristics were used. From these parental sequences, a S. cerevisiae library was created and 16 antigen specific shuffled V(HH) fragments were selected. We found that these shuffled V(HH) fragments were, (i) unique in sequence; (ii) composed of two or three parental sequences; (iii) in three V(HH)s point mutations occurred; and (iv) antigen specificity was not changed. The four highest producers in the yeast S. cerevisiae were selected and production, affinity, and antigen binding at 90 degrees C were compared with parental V(HH)s. One shuffled V(HH) was enhanced both in production (3.4-fold) and affinity (four-fold). A second shuffled V(HH) displayed increased production (1.9-fold), and improved stability (2.4-fold) in antigen binding at 90 degrees C. Structural analysis suggested that improved antigen binding is associated with the A24 --> V24 substitution, which reduces the size of the hydrophobic pit at the llama V(HH) surface. We demonstrate that it is possible to improve desired characteristics of the same V(HH) fragment simultaneously using DNA shuffling. Finally, this is one of the first examples of DNA shuffling improving temperature stability of an antibody fragment.

Isolation of antigen specific llama VHH antibody fragments and their high level secretion by Saccharomyces cerevisiae.

Recently the existence of 'heavy chain' immunoglobulins in Camelidae has been described. However, as yet there is no data on the binding of this type of antibody to haptens. In addition, it was not a priori predictable whether the binding domains (VHH) of these antibodies could be produced and secreted by the lower eukaryotic micro-organism Saccharomyces cerevisiae. In the present study these questions are addressed. Heavy chain immunoglobulins directed against two hapten molecules, the azo-dyes RR6 and RR120 as well as the (proteinaceous) human pregnancy hormone, have been raised in Lama glama. We were able to select specific VHH fragments for all three antigens by direct screening of Escherichia coli or yeast libraries, even without prior enrichment via bio-panning. This is the first example of the isolation of llama anti-hapten VHH domains. Surprisingly, the affinities of the llama VHHs for the RR6 hapten obtained in this way are in the low nM range. Furthermore, some of the antigen specific VHHs were secreted by S. cerevisiae at levels over 100 mg l-1 in shake flask cultures. These two findings extend the possible application areas for the llama VHH fragments significantly.

Prevention of diarrhoea using pathogen specific monoclonal antibodies in an experimental enterotoxigenic E. coli infection in germfree piglets.

In the present study we describe the effect of oral application of mAB specific for ETEC F4ac fimbriae in an experimental ETEC challenge model in neonatal germfree piglets. The results show that mAB, specific for different F4ac epitopes protect animals against ETEC specific pathology. Moreover, the results show that protection is independent of F4ac epitope specificity.

No exercise-induced increase in serum BDNF after cycling near a major traffic road.

Commuting by bike has a clear health enhancing effect. Moreover, regular exercise is known to improve brain plasticity, which results in enhanced cognition and memory performance. Animal research has clearly shown that exercise upregulates brain-derived neurotrophic factor (BDNF - a neurotrophine) enhancing brain plasticity. Studies in humans found an increase in serum BDNF concentration in response to an acute exercise bout. Recently, more evidence is emerging suggesting that exposure to air pollution (such as particulate matter (PM)) is higher in commuter cyclists compared to car drivers. Furthermore, exposure to PM is linked to negative neurological effects, such as neuroinflammation and cognitive decline. We carried-out a cross-over experiment to examine the acute effect of exercise on serum BDNF, and the potential effect-modification by exposure to traffic-related air pollution. Thirty eight physically fit, non-asthmatic volunteers (mean age: 43, 26% women) performed two cycling trials, one near a major traffic road (Antwerp Ring, R1, up to 260,000 vehicles per day) and one in an air-filtered room. The air-filtered room was created by reducing fine particles as well as ultrafine particles (UFP). PM10, PM2.5 and UFP were measured. The duration (∼20min) and intensity of cycling were kept the same for each volunteer for both cycling trials. Serum BDNF concentrations were measured before and 30min after each cycling trial. Average concentrations of PM10 and PM2.5 were 64.9µg/m(3) and 24.6µg/m(3) in cycling near a major ring way, in contrast to 7.7µg/m(3) and 2.0µg/m(3) in the air-filtered room. Average concentrations of UFP were 28,180 particles/cm(3) along the road in contrast to 496 particles/cm(3) in the air-filtered room. As expected, exercise significantly increased serum BDNF concentration after cycling in the air-filtered room (+14.4%; p=0.02). In contrast, serum BDNF concentrations did not increase after cycling near the major traffic route (+0.5%; p=0.42). Although active commuting is considered to be beneficial for health, this health enhancing effect could be negatively influenced by exercising in an environment with high concentrations of PM. Whether this effect is also present with chronic exercise and chronic exposure must be further elucidated.