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.

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.

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.

Norandrosterone and noretiocholanolone concentration before and after submaximal standardized exercise.

19-Norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) are the two main urinary indicators used to detect illegal use of nandrolone. Recent studies showed that 19-NA and 19-NE can be endogenously produced in non-treated humans. The concentrations were close to the threshold of the International Olympic Committee (IOC), i.e. 2 ng/ml for men and seem to increase after prolonged intense effort. Androgens are involved in the biosynthesis of estrogens and estrogen has a protective effect against skeletal muscle damage following eccentric exercise. Furthermore, the testicular tissue can synthesize 19-norandrogens from androgens, we hypothetisize that the 19-norandrogen production might be influenced by muscle damage following eccentric exercise. Therefore the purpose of this study is to examine if three different exercise methods will influence the urinary concentration of 19-NA and 19-NE in healthy young subjects. Fifteen amateur hockey players undertook a 30 min submaximal standardized exercise protocol. They were randomised for three different types of exercise, namely a cycle ergometer test (cyclic muscle activity), a treadmill test (concentric muscle activity), or a bench-steptest (eccentric muscle activity) at a target heart rate corresponding to 65 % (+/- 5 %) of Karvonen heart rate. Urine samples were obtained before the test and 60 min and 120 min after the end of exercise. Subjects completed a Likert scale of muscle soreness before and 12 h after exercise. 19-NA and 19-NE were determined by gas chromatography-tandem mass spectrometry (GC-MS-MS). Baseline urinary 19-NA and 19-NE concentrations were under limit of detection of 0.05 ng/ml, except for one sample (0.13 ng/ml). No 19-NA or 19-NE could be detected post exercise. In our experimental conditions, the exercise mode (eccentric or concentric) had no impact on 19-NA or 19-NE excretion. Our findings confirm that the current International Olympic Committee threshold level for nandrolone metabolites is sufficiently high to avoid false positive cases.

Stimulation of chymosin secretion by simultaneous expression with chymosin-binding llama single-domain antibody fragments in yeast.

We studied the effect of coexpression of chymosin and chymosin-binding llama single-domain antibody fragments (VHHs) on the secretion of chymosin by Saccharomyces cerevisiae cells. A VHH expression library containing chymosin-specific VHHs was obtained by immunization of a llama and coexpressed with chymosin in yeast. From this library, we obtained two VHH clones that stimulated chymosin secretion by screening colonies for the level of chymosin secreted. These VHHs bound biotinylated chymosin in an immunoblot procedure but failed to bind chymosin in ELISA, suggesting that their interaction with chymosin was of low affinity. In a second approach, chymosin-specific VHHs were first selected using phage display and then coexpressed with chymosin in yeast cells. Screening yeast cells for higher levels of chymosin secretion resulted in 11 VHHs. Sequence analysis revealed that these 11 VHHs formed four sets of related VHHs that were different from the previously isolated two VHHs. Although binding of VHHs to chymosin could not be demonstrated in ELISA using soluble VHHs, it could be unambiguously demonstrated for clones isolated by phage display, using phage-displayed VHHs. Finally, quantitative Western blot analysis of chymosin amounts demonstrated that coexpression with VHH domains can stimulate the level of secreted chymosin 1.5- to 6-fold.

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.

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.

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.

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.

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.

Expression of CD2 on porcine B lymphocytes.

Remarkable interspecies differences in CD2 expression on B lymphocytes have been reported in mammals. Human and rat B cells lack CD2, whilst B lymphocytes in mice are CD2+. In pigs, B cells have been supposed not to express CD2. We show here, however, that CD2 is present at a low level on a prominent subset of porcine B cells. Moreover, we describe changes in the proportions of CD2+ and CD2- B-cell subsets during ontogeny. Before contact with microflora, the majority of peripheral surface immunoglobulin M+ (sIgM+) B cells express CD2 and sIgM+CD2- B cells are rare. Shortly after colonization of conventional (CV) piglets with complex intestinal microflora, numerous CD2- B cells appear in the periphery and their relative number increases with age in both CV and specific pathogen-free (SPF) pigs. However, monoassociation of germ-free (GF) piglets with a single Escherichia coli strain does not result in a significant increase of sIgM+CD2- B cells in the periphery. We suggest that CD2 is down-regulated in porcine B lymphocytes upon activation with microflora in mucosa-associated lymphatic tissues. In bone marrow (BM), we identified putative porcine B-cell precursors. These cells express CD2 at low density and do not bear either the common myelomonocytic antigen or T and B-lymphocyte receptors. Similar to mouse and human pre-B cells, this lymphocyte-sized subset expresses CD25 and class II antigens. CD2 positivity of these cells indicates that CD2 is expressed earlier than sIgM during B lymphopoiesis in pigs.

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.