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Czarske, J.

Publications and source records attributed to Czarske, J..

6 recordsLinked to original sources

Understanding Virtual Staining with generative adversarial networks for Osteoclast Imaging

Virtual staining with generative adversarial networks is an efficient, non-invasive and scalable alternative to conventional cell staining, minimizing the need for destructive and time-consuming protocols. In this study, we investigate the explainability of a network trained to virtually stain osteoclast cultures, using intensity-based label-free input images. The model enables analysis of cell cultures without immunostaining. Explainability assessments, including receptive field and feature map analyses, show that the background in input images significantly influences staining predictions within cellular regions and the trained network performs an internal segmentation during the image transformation process. This suggests that contextual cues beyond cell boundaries are implicitly learned and integrated during training. By eliminating repetitive staining procedures, virtual staining enables longitudinal studies, allows multiplexing of individual samples, and reduces reagents and laboratory waste. Our findings enhance understanding of the virtual staining process and highlight its potential for biomedical research applications.

bioengineering↗

Influence of hyperparameters on the performance of deep learning-based microrobotic localization under phantom tissue

For the effective operation of medical microrobots within living organisms and precise targeting, it is imperative to employ imaging techniques closely integrated with real-time deep-tissue tracking methods. However, due to a typically low Signal-to-Noise ratio images with strong background, it is hard for traditional tracking methods to achieve sufficient accuracy. This challenge can be addressed by deep learning-based tracking with a real-time detection model. However, a multitude of design choices and Hyperparameters influence the performance. In this study we compared the influence of the hyperparameters and model architecture versions of the "you only look once" (YOLO) network. We use experimental data from a magnetic microrobot imaged with Photoacoustics through 5 mm phantom tissue to evaluate the tracking in comparison with an optical reference. The deep-learning based methods consistently achieved lower missing-detection ratios. Regarding the Root Mean Square localization error, we observed that increasing the weight of the box loss function and utilizing the distribution focal loss can enhance the performance by 10%. Furthermore, it can be seen that YOLOv9 consistently outperformed its predecessor YOLOv8. This study quantifies the robustness of deep-learning based tracking of medical microrobots under tissues.

bioengineering↗

Single-shot impulsive stimulated Brillouin microscopy by tailored ultrashort pulses

Brillouin microscopy has become an important tool for investigating the mechanical properties of tissue. The recently developed Impulsive stimulated Brillouin Scattering (ISBS) promises a label-free, non-invasive measurements of viscoelastic properties of transparent samples and offers the potential for a high temporal resolution. However, the spatial resolution of ISBS is currently limited, which hinders its transfer to real-world applications. Increasing the spatial resolution of ISBS leads to an increase in the energy density of the pump beams, which requires a balancing of the excitation parameters to stay below the phototoxic threshold. This paper focuses on the influences of different excitation parameters on the spatial, temporal and spectral resolution and their optimal values. Combined with the adoption of a noise suppressing window function, a measurement rate of 20{micro}s/pixel in hydrogel is achieved, which is promising for fast 3D imaging. The presented advanced impulsive stimulated Brillouin microscopy can be applied for fast tissue elastography to-ward disease studies.

biophysics↗

Tracking long-term functional connectivity maps in human stem-cell-derived neuronal networks by holographic-optogenetic stimulation

Neuronal networks derived from human induced pluripotent stem cells (hiPSCs) have been exploited widely for modelling neuronal circuits, neurological diseases and drug screening. As these networks require extended culturing periods to functionally mature in vitro, most studies are based on immature networks. To obtain insights on long-term functional features of human networks, we improved a long-term glia-co-culture culturing protocol directly on multi-electrode arrays (MEA), facilitating long-term assessment of electrical features at weekly intervals. We applied optogenetic stimulation to induce neuronal activity, which resulted in accelerated neuronal responses during network development. Using holographic stimulation with single-cell-resolution, propagating evoked activities of 400 individually stimulated neurons per MEA were traceable, and precise network functional connectivity motifs were revealed. Our integrated holographic optogenetic stimulation platform on MEAs facilitates studying long-term functional dynamics of human neuronal networks in vitro. This is an important step towards establishing hiPSC-derived neurons as profound functional testbeds for basic and biomedical research. HighlightsO_LIIntegrated platform allowed long-term optogenetic experiments on hiPSC-derived networks. C_LIO_LIFull-field optogenetic stimulation boosted hiPSC-derived neuronal network activity. C_LIO_LISingle-neuron resolution holographic stimulation evoked local responses in the network. C_LIO_LIHolographic stimulation of each neuron revealed its functional connectivity patterns. C_LIO_LISubsequent holographic stimulation of more than 400 neurons revealed the whole network connectivity map. C_LI

neuroscience↗

In situ measurement of the isoplanatic patch for imaging through intact bone

Wavefront-shaping (WS) enables imaging through scattering tissues like bone, which is important for neuroscience and bone-regeneration research. WS corrects for the optical aberrations at a given depth and field-of-view (FOV) within the sample; the extent of the validity of which is limited to a region known as the isoplanatic patch (IP). Knowing this parameter helps to estimate the number of corrections needed for WS imaging over a given FOV. In this paper, we first present direct transmissive measurement of murine skull IP using digital optical phase conjugation (DOPC) based focusing. Second, we extend our previously reported Phase Accumulation Ray Tracing (PART) method to provide in-situ in-silico estimation of IP, called correlative PART (cPART). Our results show an IP range of 1-3 m for mice within an age range of 8-14 days old and 1.00{+/-}0.25 m in a 12-week old adult skull. Consistency between the two measurement approaches indicates that cPART can be used to approximate the IP before a WS experiment, which can be used to calculate the number of corrections required within a given field of view. Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC="FIGDIR/small/246595v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@1844a5eorg.highwire.dtl.DTLVardef@2e80dforg.highwire.dtl.DTLVardef@10ecd49org.highwire.dtl.DTLVardef@c7afa9_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

Mechanical mapping of spinal cord development and repair in living zebrafish larvae using Brillouin microscopy

The mechanical properties of biological tissues are increasingly recognized as important factors in developmental and pathological processes. Most existing mechanical measurement techniques either necessitate destruction of the tissue for access or provide insufficient spatial resolution. Here, we show for the first time a systematic application of confocal Brillouin microscopy to quantitatively map the mechanical properties of spinal cord tissues during biologically relevant processes in a contact-free and non-destructive manner. Living zebrafish larvae were mechanically imaged in all anatomical planes, during development and after spinal cord injury. These experiments revealed that Brillouin microscopy is capable of detecting the mechanical properties of distinct anatomical structures without interfering with the animals natural development. The Brillouin shift within the spinal cord increased during development and transiently decreased during the repair processes following spinal cord transection. By taking into account the refractive index distribution, we explicitly determined the apparent longitudinal modulus and viscosity of different larval zebrafish tissues. Importantly, mechanical properties differed between tissues in situ and in excised slices. The presented work constitutes the first step towards an in vivo assessment of spinal cord tissue mechanics during regeneration, provides a methodical basis to identify key determinants of mechanical tissue properties and allows to test their relative importance in combination with biochemical and genetic factors during developmental and regenerative processes.

biophysics↗