Neurovascular coupling (NVC) in the brain is well studied and is one of the physical stimulation responses triggered by the central nervous system. NVC, or functional hyperemia, is described as the local blood flow increase due to the release of vasodilator chemicals from neuronal cells into vessels. This behavior also exists in the retinal vasculature. However, it was only measured in the ipsilateral retina. Assessing photic stimulation in the contralateral retina can shed light on retina-retina or brain-retina neural pathways. Emerging technologies provide new ways of measuring this effect with high spatial and temporal resolution. Adaptive optics has been used in astronomy with great results. Yet, implementing this technology in retinal fundus imaging was revolutionary in providing extremely high spatial resolution images. The RTX1 ™ is an adaptive optics retinal camera capable of ipsilateral light flicker to stimulate photoreceptors and document the induced response. The NVC in the ipsilateral retina has been successfully assessed using this equipment. Using the RTX1™ with an external flickering device, it is possible to explore contralateral stimulation's effects. The first preliminary tests show a full working prototype (contralateral stimulation) with successful software integration into the RTX1TM. A set of images was acquired to fully document the entire procedure and evaluate all components. Further evaluation will be necessary to optimize flicker-related parameters in the quest for the ipsilateral NV C response.
This study aims to investigate the impact of compressive loading on endothelial cell migration pattern in angiogenesis using a meshless discretization technique, combined with a reaction-diffusion formulation. In silico models are highly valuable for understanding the dynamics of biological systems, and numerical models allow for testing different laboratory protocols and deducing which ones produce the best outcomes. In the proposed model, angiogenesis was simulated in response to a reaction-diffusion equation for vascular endothelial growth factor (VEGF) in a 5×5 mm 2 square domain and using the Radial Point Interpolation Method (RPIM). The compressive loading was applied as a hydrostatic pressure of around 0.0067 MPa, in a specific zone in the domain to simulate the domain stress-strain interactions. The effect of compressive loading on angiogenesis sprouting patterns is analysed, and the results show that compression load affects the VEGF diffusion gradient and increases the VEGF concentration in the region where the compression was applied, causing the capillary to move away from the VEGF release region. Overall, this study sheds light on the role of mechanical stimuli in angiogenesis and provides a basis for further research in this area.
The continuous monitoring of vital signals is crucial in the diagnosis of cardiovascular diseases. With the focus on a continuous and non-intrusive acquisition of ballistocardiographic signal, a mobile seat instrumentalized with optical fiber sensors based on fiber Bragg gratings (FBGs) is proposed. The development of a six-sensor network will allow the study of the feasibility of their positioning to aim a greater efficiency. To calculate the heart rate, a time domain algorithm was developed based on the determination of the period between J-peaks of the ballistocardiograph. This model was tested on ten volunteers, in a sitting position, with data acquisitions carried out in periods of three minutes. To evaluate its performance, the results were compared with a wearable reference system, obtaining an accuracy greater than 95% for the majority of the participants, thus verifying that the developed system overcame the proposed objective.
Mesh-based numerical methods have several limitations to simulate biofluids at a micro scale level, as they do not represent the multiphase component of them. In contrast, atomistic methods have the ability to simulate fluids with more than one phase, where the mesh is replaced by interacting particles. The LAMMPS code is a classical method of the molecular dynamics simulation, frequently used to assess the flow dynamics of particles. The main goal of this work is to compare the classical Molecular Dynamics (MD) with the finite volume method. Thus, for both type of simulations the same Newtonian fluid was used to assess the flow behavior along a hyperbolic contraction microchannel. The strain rate obtained for the flow rate of 0.22 and 1.00 ml/h have shown a good agreement between both methods.
Cardiac surgery equipment assists healthcare professionals in the surgical treatment of pathologies of the heart and blood vessels. This equipment is considered critical as the patient's life depends on it. Therefore, it is crucial that the equipment manager ensures it is always in the best operating conditions and in compliance with the applicable regulatory requirements (e.g., electrical safety requirements). Three of the most used cardiac surgery devices are the intra-aortic balloon pump, the extracorporeal circulation machine and the heat exchanger. This paper presents a compilation of relevant information about this equipment, including maintenance procedures and enumeration of the most common malfunctions, based on the analysis of maintenance reports covering the lifecycle of these devices.
