Objectively assessed physical activity and weight status of primary school children in Germany with and without migration backgrounds

OBJECTIVES

Many children are insufficiently active, and children with a migration background appear to be even less active and at a higher risk of developing obesity. This study evaluated the weight status, and the frequencies and intensities of objectively assessed physical activity (PA) of children with and without a migration background.

STUDY DESIGN

Cross-sectional study.

METHODS

PA was assessed objectively for 6 days in 273 children (aged 7.1 ± 0.6 years). In total, 74 children (27%) were classified as having a migration background. PA was grouped in light and moderate-to-vigorous (MVPA) intensities. Body mass index (BMI) percentiles (BMIPCT) were determined.

RESULTS

Children without a migration background spent more time in MVPA compared with children with a migration background (138.2 ± 62.6 vs 121.7 ± 54.9 min, respectively; P < 0.01). On weekends, time in MVPA decreased significantly for all children (112.3 ± 66.0 min, P < 0.01), especially for children with a migration background (97.7 ± 56.7 min, P < 0.01). Children with a migration background displayed significantly higher BMIPCT than children without a migration background (55.7 ± 29.6 vs 44.3 ± 26.8, respectively; P < 0.01) and were significantly more often overweight and/or obese (13.5% vs 8.5%, respectively; P < 0.02).

CONCLUSIONS

Children with a migration background are less physically active and more often overweight, resulting in higher risks of developing secondary diseases. The results of this study should be considered when designing interventions to increase PA in children with a migration background.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS), DRKS-ID: DRKS00000494.

3D-based visual physical activity assessment of children

In the last decades, an alarming rise in prevalence of childhood overweight and obesity has been observed which is partly attributed to a lack in physical activity and has started to become a public health concern. Therefore, the necessity for accurate physical activity assessment has become more and more apparent. Physical activity can be assessed objectively using accelerometers or combined devices. The application of such devices is sometimes complex and wearing the device may influence the behaviour of the test person. Therefore, assessment without any worn device would be an advantage.

A RGB-D camera device captures motion of the test person in a specific measurement area. After reducing the data and subtraction of the voxel distance, an activity level can be calculated.

The calculated activity level is similar to acceleration data of common monitoring devices. The calculated activity level is the sum of the person’s activity. Little activity with small movement can be differentiated from intense activity with large movement and high acceleration as well as no activity. The data can be structured in body-activity and limb-activity. Classifying those categories increases the benefit of this assessment compared to common accelerometers.

With the RGB-D based assessment objective, contextual information of different physical activity levels can be provided. Physical activity assessment without a worn device offers advantages such as the lack of manipulation of the device and its positioning, also the person’s compliance is no issue influencing the assessment. The RGB-D based assessment is similar to acceleration data and can be converted into comparable data and units after calibration. For more specific assessments a validation with accelerometers and the calibration of the derived data is necessary.

[Development and implementation of a state-wide "train the trainer" model of the school-based prevention programme "Join the Healthy Boat - Primary School"]

STUDY AIM

This paper shows how a state-wide health-promotion intervention at primary schools can be implemented by considering the example of the programme "Join the Healthy Boat - Primary School". Additionally, it is illustrated how quality control throughout the whole process can be incorporated.

METHODS

To operate long-term and target-group orientated in the whole state of Baden-Württemberg, the school-based prevention programme "Join the Healthy Boat" uses a "train the trainer" model. The trainers are teachers who were instructed by the project team. In the school year 2009/10, these trainers offered quadrinominal training courses for further teachers. Every urban and rural district is covered by 1 trainer. The trainers evaluated the 6 preparatory training courses they had been given using questionnaires. The following 4 training courses the trainers offered to the teachers were reviewed by the trainers as well as the teachers using questionnaires, too. Additionally, at the end of the school year 2009/10, the teachers completed a questionnaire about their satisfaction regarding the programme itself and the work with the trainer.

RESULTS

During the school year 2009/10, 453 teachers were trained by 32 trainers. According to indications on the questionnaires about the preparatory training courses, all trainers felt themselves "very well" or "well" prepared for their task. The teachers evaluated the expertise of the respective trainer, the quality of the training courses and the satisfaction with the programme itself throughout highly.

CONCLUSION

Based on the excellent results of the process evaluation and the programme's wide coverage, an adoption of a "train the trainer" model seems worthwhile for other school-based prevention programmes, as well.

Hydrogel Microwell Arrays Allow the Assessment of Protease-Associated Enhancement of Cancer Cell Aggregation and Survival

Current routine cell culture techniques are only poorly suited to capture the physiological complexity of tumor microenvironments, wherein tumor cell function is affected by intricate three-dimensional (3D), integrin-dependent cell-cell and cell-extracellular matrix (ECM) interactions. 3D cell cultures allow the investigation of cancer-associated proteases like kallikreins as they degrade ECM proteins and alter integrin signaling, promoting malignant cell behaviors. Here, we employed a hydrogel microwell array platform to probe using a high-throughput mode how ovarian cancer cell aggregates of defined size form and survive in response to the expression of kallikreins and treatment with paclitaxel, by performing microscopic, quantitative image, gene and protein analyses dependent on the varying microwell and aggregate sizes. Paclitaxel treatment increased aggregate formation and survival of kallikrein-expressing cancer cells and levels of integrins and integrin-related factors. Cancer cell aggregate formation was improved with increasing aggregate size, thereby reducing cell death and enhancing integrin expression upon paclitaxel treatment. Therefore, hydrogel microwell arrays are a powerful tool to screen the viability of cancer cell aggregates upon modulation of protease expression, integrin engagement and anti-cancer treatment providing a micro-scaled yet high-throughput technique to assess malignant progression and drug-resistance.

Diagnostic microchip to assay 3D colony-growth potential of captured circulating tumor cells

Microfluidic technology has been successfully applied to isolate very rare tumor-derived epithelial cells (circulating tumor cells, CTCs) from blood with relatively high yield and purity, opening up exciting prospects for early detection of cancer. However, a major limitation of state-of-the-art CTC-chips is their inability to characterize the behavior and function of captured CTCs, for example to obtain information on proliferative and invasive properties or, ultimately, tumor re-initiating potential. Although CTCs can be efficiently immunostained with markers reporting phenotype or fate (e.g. apoptosis, proliferation), it has not yet been possible to reliably grow captured CTCs over long periods of time and at single cell level. It is challenging to remove CTCs from a microchip after capture, therefore such analyses should ideally be performed directly on-chip. To address this challenge, we merged CTC capture with three-dimensional (3D) tumor cell culture on the same microfluidic platform. PC3 prostate cancer cells were isolated from spiked blood on a transparent PDMS CTC-chip, encapsulated on-chip in a biomimetic hydrogel matrix (QGel™) that was formed in situ, and their clonal 3D spheroid growth potential was assessed by microscopy over one week in culture. The possibility to clonally expand a subset of captured CTCs in a near-physiological in vitro model adds an important element to the expanding CTC-chip toolbox that ultimately should improve prediction of treatment responses and disease progression.

Controlled breast cancer microarrays for the deconvolution of cellular multilayering and density effects upon drug responses

Background

Increasing evidence shows that the cancer microenvironment affects both tumorigenesis and the response of cancer to drug treatment. Therefore in vitro models that selectively reflect characteristics of the in vivo environment are greatly needed. Current methods allow us to screen the effect of extrinsic parameters such as matrix composition and to model the complex and three-dimensional (3D) cancer environment. However, 3D models that reflect characteristics of the in vivo environment are typically too complex and do not allow the separation of discrete extrinsic parameters.

Methodology/Principal Findings

In this study we used a poly(ethylene glycol) (PEG) hydrogel-based microwell array to model breast cancer cell behavior in multilayer cell clusters that allows a rigorous control of the environment. The innovative array fabrication enables different matrix proteins to be integrated into the bottom surface of microwells. Thereby, extrinsic parameters including dimensionality, type of matrix coating and the extent of cell-cell adhesion could be independently studied. Our results suggest that cell to matrix interactions and increased cell-cell adhesion, at high cell density, induce independent effects on the response to Taxol in multilayer breast cancer cell clusters. In addition, comparing the levels of apoptosis and proliferation revealed that drug resistance mediated by cell-cell adhesion can be related to altered cell cycle regulation. Conversely, the matrix-dependent response to Taxol did not correlate with proliferation changes suggesting that cell death inhibition may be responsible for this effect.

Conclusions/Significance

The application of the PEG hydrogel platform provided novel insight into the independent role of extrinsic parameters controlling drug response. The presented platform may not only become a useful tool for basic research related to the role of the cancer microenvironment but could also serve as a complementary platform for in vitro drug development.

Identification of in vitro HSC fate regulators by differential lipid raft clustering

Most hematopoietic stem cells (HSC) in the bone marrow reside in a quiescent state and occasionally enter the cell cycle upon cytokine-induced activation. Although the mechanisms regulating HSC quiescence and activation remain poorly defined, recent studies have revealed a role of lipid raft clustering (LRC) in HSC activation. Here, we tested the hypothesis that changes in lipid raft distribution could serve as an indicator of the quiescent and activated state of HSCs in response to putative niche signals. A semi-automated image analysis tool was developed to map the presence or absence of lipid raft clusters in live HSCs cultured for just one hour in serum-free medium supplemented with stem cell factor (SCF). By screening the ability of 19 protein candidates to alter lipid raft dynamics, we identified six factors that induced either a marked decrease (Wnt5a, Wnt3a and Osteopontin) or increase (IL3, IL6 and VEGF) in LRC. Cell cycle kinetics of single HSCs exposed to these factors revealed a correlation of LRC dynamics and proliferation kinetics: factors that decreased LRC slowed down cell cycle kinetics, while factors that increased LRC led to faster and more synchronous cycling. The possibility of identifying, by LRC analysis at very early time points, whether a stem cell is activated and possibly committed upon exposure to a signaling cue of interest could open up new avenues for large-scale screening efforts.

Biomaterials meet microfluidics: building the next generation of artificial niches

Biomaterials are increasingly being developed as in vitro microenvironments mimicking in vivo stem cell niches. However, current macroscale methodologies to produce these niche models fail to recapitulate the spatial and temporal characteristics of the complex native stem cell regulatory systems. Microfluidic technology offers unprecedented control over the spatial and temporal display of biological signals and therefore promises new avenues for stem cell niche engineering. Here we discuss how the two approaches can be combined to generate more physiological models of stem cell niches that could facilitate the identification of new mechanisms of stem cell regulation, profoundly impacting drug discovery and ultimately therapeutic applications of stem cells.

Optimization of microfluidic single cell trapping for long-term on-chip culture

The poor efficiency of microfluidic single cell trapping is currently restricting the full potential of state-of-the-art single cell analyses. Using fluid dynamics simulations in combination with particle image velocimetry to systematically optimize trap architectures, we present a microfluidic chip with enhanced single cell trapping and on-chip culture performance. Upon optimization of trap geometries, we measured trapping efficiencies of up to 97%. Our device also enables the stable, relatively long-term culture of individual non-adherent mammalian cells in high-throughput without a significant decrease in cell viability. As a first application of this platform we demonstrate the automated separation of the two daughter cells generated upon single cell division. The reliable trapping and re-trapping of mammalian cells should for example provide the fundament for novel types of investigations in stem cell and tumour cell biology, which depend on reliable tracking of genealogical relationships such as in stem cell lineage tracking.

Micropatterning of hydrogels by soft embossing

Conventional in situ hydrogel micropatterning techniques work successfully for relatively stiff hydrogels, but they often result in locally damaged surfaces upon demolding in the case of soft and fragile polymer networks formed at low precursor concentration. To overcome this limitation, we have developed a versatile method, termed soft embossing, for the topographical micropatterning of fragile chemically cross-linked polymer hydrogels. Soft embossing is based on the imprinting of a microstructured template into a gel surface that is only partially cross-linked. Free functional groups continue to be consumed and upon complete cross-linking irreversibly confine the microstructure on the gel surface. Here we identify and optimize the parameters that control the soft embossing process and show that this method allows the fabrication of desired topographies with good fidelity. Finally, one of the produced gel micropatterns, an array of microwells, was successfully utilized forculturing and analyzing live single hematopoietic stem cells. Confining the stem cells to their microwells allowed for efficient quantification of their growth potential during in vitro culturing.

Enhancing the reliability and throughput of neurosphere culture on hydrogel microwell arrays

The neurosphere assay is the standard retrospective assay to test the self-renewal capability and multipotency of neural stem cells (NSCs) in vitro. However, it has recently become clear that not all neurospheres are derived from a NSC and that on conventional cell culture substrates, neurosphere motility may cause frequent neurosphere "merging" [Nat Methods 2006;3:801-806; Stem Cells 2007;25:871-874]. Combining biomimetic hydrogel matrix technology with microengineering, we developed a microwell array platform on which NSC fate and neurosphere formation can be unequivocally attributed to a single founding cell. Using time-lapse microscopy and retrospective immunostaining, the fate of several hundred single NSCs was quantified. Compared with conventional neurosphere culture methods on plastic dishes, we detected a more than 100% increase in single NSC viability on soft hydrogels. Effective confinement of single proliferating cells to microwells led to neurosphere formation of vastly different sizes, a high percentage of which showed stem cell phenotypes after one week in culture. The reliability and increased throughput of this platform should help to better elucidate the function of sphere-forming stem/progenitor cells independent of their proliferation dynamics. Disclosure of potential conflicts of interest is found at the end of this article.