Circulating tumor cells (CTCs) that enter the bloodstream play an important role in the formation of metastases. The prognostic significance of CTCs as biomarkers obtained from liquid biopsies is ...intensively investigated and requires accurate methods for quantification. The purpose of this study was the capture of CTCs on an optically accessible surface for real-time quantification. A filtration device was fabricated from a transparent material so that capturing of cells could be observed microscopically. Blood samples were spiked with stained tumor cells and the sample was filtrated using a porous structure with pore sizes of 7.4 µm. The possible removal of lysed erythrocytes and the retention of CTCs were assessed. The filtration process was observed in real-time using fluorescence microscopy, whereby arriving cells were counted in order to determine the number of CTCs present in the blood. Through optimization of the microfluidic channel design, the cell retention rate could be increased by 13% (from 76% ± 7% to 89% ± 5%). Providing the possibility for real-time detection significantly improved quantification efficiency even for the smallest cells evaluated. While end-point evaluation resulted in a detection rate of 63% ± 3% of the spiked cells, real-time evaluation led to an increase of 21% to 84% ± 4%. The established protocol provides an advantageous and efficient method for integration of fully automated sample preparation and CTC quantification into a lab-on-a-chip system.
Biomimetic nanocrystalline apatites analogous to bone mineral can be prepared using soft chemistry. Due to their high similarity to bone apatite, as opposed to stoichiometric hydroxyapatite for ...example, they now represent an appealing class of compounds to produce bioactive ceramics for which drug delivery and ion exchange abilities have been described extensively. However, immersion in aqueous media of dried non-carbonated biomimetic apatite crystals may generate an acidification event, which is often disregarded and not been clarified to-date. Yet, this acidification process could limit their further development if it is not understood and overcome if necessary. This may, for example, alter biological test outcomes, during their evaluation as bone repair materials, due to potentially deleterious effects of the acidic environment on cells, especially in in vitro static conditions. In this study, we explore the origins of this acidification phenomenon based on complementary experimental data and we point out the central role of the hydrated ionic layer present on apatite nanocrystals. We then propose a practical strategy to circumvent this acidification effect using an adequate post-precipitation equilibration step that was optimized. Using this enutralization protocol, we then showed the possibility of performing (micro)biological assessments on such compounds and provide an illustration with the examples of post-equilibrated Cu
- and Ag
-doped nanocrystalline apatites. We demonstrate their non-cytotoxicity to osteoblast cells and their antibacterial features as tested versus five major pathogens involved in bone infections, therefore pointing to their relevance in the field of antibacterial bone substitutes. The preliminary in vivo implantation of a relevant sample in a rat's calvarial defect confirmed its biocompatibility and the absence of adverse reaction. Understanding and eliminating this technical barrier should help promoting biomimetic apatites as a genuine new class of biomaterial-producing compounds for bone regeneration applications, e.g., with antibacterial features, far from being solely considered as "laboratory curiosities".
Biomimetic nanocrystalline calcium-deficient apatite compounds are particularly attractive for the setup of bioactive bone-repair scaffolds due to their high similarity to bone mineral in terms of ...chemical composition, structural and substructural features. As such, along with the increasingly appealing development of moderate temperature engineered routes for sample processing, they have widened the armamentarium of orthopedic and maxillofacial surgeons in the field of bone tissue engineering. This was made possible by exploiting the exceptional surface reactivity of biomimetic apatite nanocrystals, capable of easily exchanging ions or adsorbing (bio)molecules, thus leading to highly-versatile drug delivery systems. In this contribution we focus on the preparation of hybrid materials combining biomimetic nanocrystalline apatites and enzymes (lysozyme and subtilisin). This paper reports physico-chemical data as well as cytotoxicity evaluations towards Cal-72 osteoblast-like cells and finally antimicrobial assessments towards selected strains of interest in bone surgery. Biomimetic apatite/enzyme hybrids could be prepared in varying buffers. They were found to be non-cytotoxic toward osteoblastic cells and the enzymes retained their biological activity (e.g. bond cleavage or antibacterial properties) despite the immobilization and drying processes. Release properties were also examined. Beyond these illustrative examples, the concept of biomimetic apatites functionalized with enzymes is thus shown to be useable in practice, e.g. for antimicrobial purposes, thus widening possible therapeutic perspectives.
The mechanical and viscoelastic properties of intact wheat kernels of 36 wheat cultivars differing in low molecular weight glutenin subunit (LMW-GS) composition (loci Glu-A3, Glu-B3, and Glu-D3) were ...evaluated using load-compression tests. Comparison among genotypic groups representing Glu-3 allelic variants showed that groups representing the alleles Glu-A3 b, c, and d; Glu-B3 d, g, and h; and Glu-D3 a, b, and d, had harder kernel texture, higher kernel elastic work and larger gluten strength-related parameters than those possessing alleles Glu-A3 e; Glu-B3 f, i and j (translocation 1B/1R); and Glu-D3 d. Modulus of elasticity (stress to strain ratio) showed low values (111.9-168.8 MPa) for allelic groups possessing poor elastic properties (Glu-A3 e; Glu-B3 f, i, and j; and Glu-D3 d), and high values (179.8-222.6 MPa) for allelic groups possessing high kernel elastic properties (Glu-A3 b c, and d; Glu-B3 d, g, and h; and Glu-D3 a, b and c). The highest values for gluten strength-related parameters (SDS-sedimentation, dough mixing time, and dough strength W) corresponded to allelic groups Glu-A3 d; Glu-B3 d and g; and Glu-D3 d, while the lowest corresponded to Glu-A3 e and Glu-B3 j. No significant differences were observed among groups with regard to gluten extensibility parameters; however, the highest P/L value (least extensibility) corresponded to Glu-B3 j, which indicates presence of 1B/1R translocation. Except for the Glu-B3 j (translocation 1B/1R) allele, which presented more variation within samples, a general relationship between kernel viscoelastic properties and dough viscoelastic properties was observed; samples showing higher elastic work to plastic work ratio (E/P) tended to possess better gluten strength than cultivars with low E/P ratio.
High and low molecular weight glutenin subunits (HMW-GS and LMW-GS, respectively) are the main factors determining the viscoelastic properties of wheat dough. The mechanical and viscoelastic ...properties of 29 samples of wheat kernels differing in HMW-GS were evaluated with load-compression tests. Samples were grouped by genotypes differing in HMW-GS composition (allelic variants: Glu-A1: null, 1, 2*; Glu-B1: 7, 7+8, 7+9, 13+16, and 17+18; Glu-D1: 5+10, 2+12). Groups representing Glu-A1 1 and 2*; Glu-B1 7, 7+9 and 17+18; and Glu-D1 5+10 generally possessed hard grain and showed the largest kernel elasticity values, while those representing subunits Glu-A1 null; Glu-B1 7+8; and Glu-D1 2+12 had soft kernels and showed lower elastic work values. Genotypes possessing HMW-GS 1, 17+18 and 5+10 gave large SDS-sedimentation values and better dough viscoelastic properties than those with allelels: null, 7+8, and 2+12. Kernel hardness showed significant correlation with the dough-strength-related parameters: SDS-sedimentation; dough mixing time; and the alveographic parameters, W and P. There was a negative correlation between kernel plastic work and dough mixing time and the dough tenacity/extensibility parameters, P/L. The significant relationship between sedimentation tests and kernel elastic work seems to indicate that elastic work is related to genotype (protein composition). The general tendency was that higher values in kernel elastic work and size corresponded to better dough rheological quality. Mechanical properties of the kernel were significantly related to the elastic behavior measured in a single wheat kernel. The use of the compression test on individual kernels is easy, rapid and nondestructive and therefore seems to show potential use as a rapid tool in breeding to improve wheat quality.
Fine PTFE tubes are used in high‐end and high cost devices like flexible Endoscopes where no standard sterilization procedure like autoclaving applies due to material properties. The study of ...innovative decontamination processes like plasma sterilization request appropriate analysis methods in order to verify the process functionality. In a related research project the IGB‐cycle‐method for contamination and recovery of indicator organisms like Bacillus atrophaeus spores was developed. It was possible to proof the IGB‐cycle‐method to be reproducible and reliable using round robin tests between three laboratories that compared their results in reference to a relevant level of contamination and recovery. Of a relevant contamination more than 7 log10 steps of cfu/specimen could be recovered from the tube surface.
This work deals with the preparation of reliable test specimen for the evaluation and quantification of plasma sterilization treatment for small tube medical devices. Standardization was realized using inter laboratory comparison. The developed specimen represents an analogy to flexible endoscopes where standardized sterilization methods cannot apply due to material properties like thermo sensitivity (autoclaving) or critical periods of outgassing needed (EtO).
Today more and more thermo‐labile medical devices are applied, which have to be decontaminated with low‐temperature sterilization methods. One method under development is the low‐temperature plasma. ...For the comparability of the antimicrobial efficacy of two low‐temperature plasma setups in fine‐lumen polytetrafluoroethylene (PTFE) tubes, independent of performer, round robin tests with Bacillus atrophaeus and Geobacillus stearothermophilus spores loaded with 0.3% BSA were done. All in all six test series were necessary to standardize the process and to achieve comparability, reproducibility, and microbiological variability. The results provide new evidence to the importance of standardization in microbiological investigations in terms of decontamination. This new tool is useable for established and new decontamination and sterilization equipment.
The comparability of the microbicidal efficacy in long fine‐lumen PTFE‐tubes of two different plasma setups, one low and one atmospheric pressure plasma is shown. The comparability is achieved by a complete standardization of microbiological parameters and is proved by multicentre trials. The decontamination efficiency raised up to 6 log10 cfu/specimen by plasma treatment optimization.
In the project I-CARE a technical system for tablet devices is developed that captures the personal needs and skills of people with dementia. The system provides activation content such as music ...videos, biographical photographs and quizzes on various topics of interest to people with dementia, their families and professional caregivers. To adapt the system, the activation content is adjusted to the daily condition of individual users. For this purpose, emotions are automatically detected through facial expressions, motion, and voice. The daily interactions of the users with the tablet devices are documented in log files which can be merged into an event list. In this paper, we propose an advanced format for event lists and a data analysis strategy. A transformation scheme is developed in order to obtain datasets with features and time series for popular methods of data mining. The proposed methods are applied to analysing the interactions of people with dementia with the I-CARE tablet device. We show how the new format of event lists and the innovative transformation scheme can be used to compress the stored data, to identify groups of users, and to model changes of user behaviour. As the I-CARE user studies are still ongoing, simulated benchmark log files are applied to illustrate the data mining strategy. We discuss possible solutions to challenges that appear in the context of I-CARE and that are relevant to a broad range of applications.
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