Quantitative imaging of the collective cell movements shaping an embryo

The recent development of imaging and image processing techniques, such as 4D microscopy and 3D cell tracking, enables analysis through quantification of the movement of large cell populations in vivo. These imaging approaches provide an opportunity to study embryonic morphogenesis during development from the level of cellular processes to the scale of entire organism. Image analysis reveals cell collective behaviors that shape an embryo and offers some surprising insights into the cell-cell interactions involved in concerted movements. We illustrate the power of this approach by studying the early development of Drosophila embryos

Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

© 2016 The Authors.Fluorescent proteins and dyes are routine tools for biological research to describe the behavior of genes, proteins, and cells, as well as more complex physiological dynamics such as vessel permeability and pharmacokinetics. The use of these probes in whole body in vivo imaging would allow extending the range and scope of current biomedical applications and would be of great interest. In order to comply with a wide variety of application demands, in vivo imaging platform requirements span from wide spectral coverage to precise quantification capabilities. Fluorescence molecular tomography (FMT) detects and reconstructs in three dimensions the distribution of a fluorophore in vivo. Noncontact FMT allows fast scanning of an excitation source and noninvasive measurement of emitted fluorescent light using a virtual array detector operating in free space. Here, a rigorous process is defined that fully characterizes the performance of a custom-built horizontal noncontact FMT setup. Dynamic range, sensitivity, and quantitative accuracy across the visible spectrum were evaluated using fluorophores with emissions between 520 and 660 nm. These results demonstrate that high-performance quantitative three-dimensional visible light FMT allowed the detection of challenging mesenteric lymph nodes in vivo and the comparison of spectrally distinct fluorescent reporters in cell culture

Antibody-antigen interactions: What is the required time to equilibrium?

The use of antibodies is widespread in many areas including in-vivo and in-vitro diagnostics, quantitative analysis in research laboratories and as therapeutic substances. Since the methods for generation of antibodies has improved and regularly results in high-affinity interactions, the standard assays used for quantification of the interaction properties should be revisited because they do not necessarily produce accurate results. Here we show that in several cases, the affinity determination of strongly binding antibodies will be inherently difficult when using standard procedures, due to impractically long incubation times. Real-time kinetic analysis is often the only realistic alternative for affinity determination

In Vivo Corrosion of Two Novel Magnesium Alloys ZEK100 and AX30 and Their Mechanical Suitability as Biodegradable Implants

In magnesium alloys, the components used modify the alloy properties. For magnesium implants in contact with bone, rare earths alloys are commonly examined. These were shown to have a higher corrosion resistance than other alloys and a high mechanical strength, but their exact composition is hard to predict. Therefore a reduction of their content could be favorable. The alloys ZEK100 and AX30 have a reduced content or contain no rare earths at all. The aim of the study was to investigate their in vivo degradation and to assess the suitability of the in vivo μCT for the examination of their corrosion. Implants were inserted in rabbit tibiae. Clinical examinations, X-rays and in vivo μCT scans were done regularly. Afterwards implants were analyzed with REM, electron dispersive X-ray (EDX), weighing and mechanical testing. The in vivo μCT is of great advantage, because it allows a quantification of the corrosion rate and qualitative 3D assessment of the corrosion morphology. The location of the implant has a remarkable effect on the corrosion rate. Due to its mechanical characteristics and its corrosion behavior, ZEK100 was judged to be suitable, while AX30, which displays favorable degradation behavior, has too little mechanical strength for applications in weight bearing bones

Shunt quantification in congenital heart disease based on two-dimensional speckle tracking

In this work we investigated how high frame rate speckle tracking based on plane wave imaging could be used to improve the quantification of peak velocities in shunt flows due to septal defects. Simulated jet flow was used to optimize acquisition and tracking parameters. In vivo, a packet based acquisition scheme was used where focused B-mode scans were interleaved high frame rate flow images (100 fps). Results showed that speckle tracking provides calibrated velocities in the shunt flow throughout the cardiac cycle, and improved estimates of peak velocities used for diagnosing shunt severity were acquired

Pitfall in the high-throughput quantification of whole blood cyclosporin A using liquid chromatography-tandem mass spectrometry

In a growing number of laboratories the technique of liquid chromatography-tandem mass spectrometry is used for the quantification of cyclosporin A in whole blood, employing cyclosporin D as the internal standard. Cyclosporin A is extensively metabolized in vivo; in liquid chromatography-tandem mass spectrometry respective metabolites can give rise to both parent and product ions that are isobaric with ions commonly used for the detection of cyclosporin A and cyclosporin D, respectively. In this article it is demonstrated that limited chromatography with co-elution of such metabolites together with cyclosporin A and cyclosporin D can lead to incorrect results

Detection of Metabolites by Proton Ex Vivo NMR, in Vivo MR Spectroscopy Peaks and Tissue Content Analysis: Biochemical-Magnetic Resonance Correlation: Preliminary Results

*Aim*: Metabolite concentrations by in vivo magnetic resonance spectroscopy and ex vivo NMR spectroscopy were compared with excised normal human tissue relaxation times and tissue homogenate contents.

*Hypothesis*: Biochemical analysis combined with NMR and MR spectroscopy defines better tissue analysis.

*Materials and Methods*: Metabolites were measured using peak area, amplitude and molecular weights of metabolites in the reference solutions. In normal brain and heart autopsy, muscle and liver biopsy tissue ex vivo NMR peaks and spin-lattice (T1) and spin-spin (T2) relaxation times, were compared with diseased tissue NMR data in meningioma brain, myocardial infarct heart, duchene-muscular-dystrophy muscle and diffused-liver-injury liver after respective in vivo proton MR spectroscopy was done. NMR data was compared with tissue homogenate contents and serum levels of biochemical parameters.

*Results*: The quantitation of smaller NMR visible metabolites was feasible for both ex vivo NMR and in vivo MR spectroscopy. Ex vivo H-1 NMR and in vivo MRS metabolite characteristic peaks (disease/normal data represented as fold change), T1 and T2, and metabolites in tissue homogenate and serum indicated muscle fibrosis in DMD, cardiac energy depletion in MI heart, neuronal dysfunction in meningioma brain and carbohydrate-lipid metabolic crisis in DLI liver tissues.

*Conclusion*: This preliminary report highlights the biochemical-magnetic resonance correlation as basis of magnetic resonance spectroscopic imaging data interpretation of disease