No abstract

Night-time driving is more dangerous than day-time driving -particularly for older drivers. Three to four times as many deaths occur at night than in the day

Cardiotoxicity is one of the most serious side effects of cancer chemotherapy. Current approaches to monitoring of chemotherapy‐induced cardiotoxicity (CIC) as well as model systems that develop in vivo or in vitro CIC platforms fail to notice early signs of CIC. Moreover, breast cancer (BC) patients with preexisting cardiac dysfunctions may lead to different incident levels of CIC. Here, a model is presented for investigating CIC where not only induced pluripotent stem cell (iPSC)‐derived cardiac tissues are interacted with BC tissues on a dual‐organ platform, but electrochemical immuno‐aptasensors can also monitor cell‐secreted multiple biomarkers. Fibrotic stages of iPSC‐derived cardiac tissues are promoted with a supplement of transforming growth factor‐β 1 to assess the differential functionality in healthy and fibrotic cardiac tissues after treatment with doxorubicin (DOX). The production trend of biomarkers evaluated by using the immuno‐aptasensors well‐matches the outcomes from conventional enzyme‐linked immunosorbent assay, demonstrating the accuracy of the authors’ sensing platform with much higher sensitivity and lower detection limits for early monitoring of CIC and BC progression. Furthermore, the versatility of this platform is demonstrated by applying a nanoparticle‐based DOX‐delivery system. The proposed platform would potentially help allow early detection and prediction of CIC in individual patients in the future.

A major challenge in 3D extrusion bioprinting is the limited number of bioink that fulfills the opposing requirements for printability with requisite rheological properties and for functionality with desirable microenvironment. Here, this limitation is addressed by developing a generalizable strategy for formulating a cell-laden microgel-based biphasic (MB) bioink. The MB bioink comprises two components, that is, microgels in closepacked condition providing excellent rheological properties for extrusion bioprinting, and a hydrogel precursor that forms a second polymer network to integrate the microgels together, providing post-printing structural stability. This strategy enables the effective printing of a range of hydrogels into complex structures with high shape fidelity. The MB bioink offers great mechanical tunability without compromising printability, and hyperelasticity with superb cyclic compression and stretch endurance. Moreover, the microgels and hydrogel precursor of the MB bioink can encapsulate different types of cells, together creating a heterogeneous cellular microenvironment at microscale. It is successfully demonstrated that hepatocytes and endothelial cells with spatial cell patterning by using MB bioink induce the cellular reorganization and vascularization, leading to enhanced hepatic functions. The proposed MB bioink expands the palette of available bioinks and opens numerous opportunities for the biomedical applications such as tissue engineering and soft robotics.

The ability to fabricate three-dimensional (3D) thick vascularized myocardial tissue could enable scientific and technological advances in tissue engineering and drug screening, and may accelerate its application in myocardium repair. In this study, we developed a novel biomimetic scaffold integrating oriented micro-pores with branched channel networks to mimic the anisotropy and vasculature of native myocardium. The oriented micro-pores were fabricated using an ‘Oriented Thermally Induced Phase Separation (OTIPS)’ technique, and the channel network was produced by embedding and subsequently dissolving a 3D-printed carbohydrate template after crosslinking. Micro-holes were incorporated on the wall of channels, which greatly enhanced the permeability of channels. The effect of the sacrificial template on the formation of oriented micro- pores was assessed. The mechanical properties of the scaffold were tuned by varying the temperature gradient and chitosan/collagen ratio to match the specific stiffness of native heart tissue. The engineered cardiac tissue achieved synchronized beating with electrical stimulation. Calcium transient results suggested the formation of connection between cardiomyocytes within scaffold. All the results demonstrated that the reported scaffold has the potential to induce formation of a perfusable vascular network and to create thick vascularized cardiac tissue that may advance further clinical applications.

Suitable material for scaffolds that support cell attachment, proliferation, vascularization and contraction has always been a challenge in myocardial tissue engineering. Much research effort has been focused on natural polymers including collagen, gelatin, chitosan, fibrin, alginate, etc. Among them, a collagen/chitosan composite scaffold was widely used for myocardial tissue engineering. Due to the non-proliferative and contractile characteristics of cardiomyocytes, the biocompatibility and mechanical properties of the scaffolds are extremely important for supporting intercellular connection and tissue function for myocardial tissue engineering. To the best of our knowledge, the three crosslinking agents (glutaraldehyde (GTA), genipin (GP), tripolyphosphate (TPP)) have not yet been comparatively studied in myocardial tissue engineering. Thus, the aim of this study is to compare and identify the crosslinking effect of GTA, GP and TPP for myocardial tissue engineering. The collagen/chitosan scaffolds prepared with various crosslinking agents were fabricated and evaluated for physical characteristics, biocompatibility and contractile performance. All the groups of scaffolds exhibited high porosity (>65%) and good swelling ratio suitable for myocardial tissue engineering. TPP crosslinked scaffolds showed excellent mechanical properties, with their elastic modulus (81.0 ± 8.1 kPa) in the physiological range of native myocardium (20∼100 kPa). Moreover, GP and TPP crosslinked scaffolds exhibited better biocompatibility than GTA crosslinked scaffolds, as demonstrated by the live/dead staining and proliferation assay. In addition, cardiomyocytes within TPP crosslinked scaffolds showed the highest expression of cardiac-specific marker protein and the best contractile performance. To conclude, of the three crosslinking agents, TPP was recommended as the most suitable crosslinking agent for collagen/chitosan scaffold in myocardial tissue engineering.

No abstract

We show how to determine the time to contact from time varying images using only accumulated sums of suitable products of image brightness derivatives. There is no need for feature or object detection, tracking of features, estimation of optical flow, or any "higher level" processing. This so-called "direct" method for determining the time to contact is based on analysis of the motion field resulting from rigid body motion under perspective projection and the constant brightness assumption. The method has essentially no latency, since it can be based on analysis of just two frames of a video sequence, and does not require a calibrated camera. An implementation of the method is demonstrated on synthetic image sequences and stop motion sequences -where the ground truth is accurately know -as well as on video sequences taken by a camera mounted on moving vehicles. I. BackgroundThe time to contact (TTC) is defined as the time that would elapse before the center of projection (COP) reaches the surface being viewed if the current relative motion between the camera and the surface were to continue without change. The TTC is essentially the ratio of distance to velocity:where Z is the distance from the center of projection (COP) to the object, while W = dZ/dt is the velocity at which the object is moving relative to the COP (which will be negative if the object is approaching the camera). While distance and velocity can not be recovered from images taken with a single camera without additional information, such as the principal distance and the size of the object, the ratio of distance to velocity can be recovered directly, even with an uncalibrated sensor. Consider a simple situation where the camera is approaching an elongated planar object lying perpendicular to the optical axis, with the direction of translational motion along the optical axis. If the (linear) size of the object is S and the size of its image is s, then, from the perspective projection equation, we have (s/f ) = (S /Z), that is, sZ = f S. Differentiating w.r.t time yieldsTogether with (1), this shows that the TTC is equal to the ratio of the size s of the image of the object to the rate of change of the size, that isIt is convenient to use the inter-frame interval as the unit of time and express the TTC as a multiple of that interval. Naturally, formulae such as (3) beg the question of how one determines the size of the image of an object and the change in that size over time [12]. In order to use the formulae, one has to be able to extract features and track features from frame to frame. In addition, this idea does not easily generalize to translational motions that do not happen to be along the optical axis -or to objects other than planar ones that happen to lie at right angles to the optical axis.Further, the time varying image is sampled at regular intervals and the time derivative of size is estimated using the difference between sizes of the images of the object in two frames. High accuracy is needed in measuring the size of the image in order...