The neuro-inflammation and excitotoxicity in perinatal brain injury: The emerging role of brain mast cells

Perinatal brain injury is a serious neurodevelopmental problem that can be occurred in preterm and term newborn infants. It is well established that neuro-inflammation is implicated in the pathophysiology of perinatal brain injury. The excitotoxicity is considered as a common molecular mechanism of perinatal brain injury. These insults are capable of leading to neuro-inflammation, but however neuro-inflammation is also able to induce the excitotoxicity in the developing brain. Thus, neuro-inflammation is both a cause and a consequence of excitotoxicity resulting in the brain damages during perinatal period. Excessive glutamate accumulation in the synaptic cleft in the brain is a prominent mechanism in the excitotoxicity while vasoactive and pro-inflammatory mediators such as histamine, prostaglandins, interleukin 1 (IL-1) β and tumor necrosis factor (TNF)-α released from brain-resident immune cells play a major role in neuro-inflammation that lead to the brain damages. Although the role of brain-resident microglial cells has been well documented in these neuro-inflammation processes, evidence for the role of brain mast cells (BMCs) has recently begun to emerge. Growing evidence indicates that brain mast cells are first responders of inflammatory insults in the developing brain and their activation is involved in induced brain injury. We have recently demonstrated that ibotenate-induced excitotoxicity leads to the activation of brain mast cells in a model of ibotenate-induced brain injury in newborn rats. Thus, in this review we point out the current knowledge on the bidirectional role of brain mast cells in neuro-inflammation and excitotoxicity underlying perinatal brain injury

Effect of COVID-19 pandemic on children undergone percutaneous endoscopic gastrostomy due to neurologic diseases

Aim: To investigate the effects of SAR-CoV-2 infection on nutritional status in patients who underwent percutaneous endoscopic gastrostomy (PEG) for neurological disorders. Methods: The clinical and laboratory follow-up data of the patients who underwent PEG in our clinic between 2002 and 2018 were evaluated before and during the pandemic. The results were analyzed statistically. Results: Twenty patients were included. They were 70.9±64.4 months old at the time of PEG, 97.9±67.8 months before the pandemic, and 105.5±60.8 months during the pandemic (p=0.048). Weight for age at the time of PEG increased from 10.7±4.6 kg to 15.6±7.2 kg before the pandemic. Hemoglobin was 12.3±1.4 g/dl at the time of PEG, 13.5±1.6 g/dl before the pandemic (p=0.045). Vitamin D was 24.1±8.9 ng/ml at the time of PEG and increased to 45.7±9.7 ng/ml during the pandemic (p=0.018). The annual number of visits before the pandemic was 9.8±5.7 and decreased to 2±1.7 during the pandemic (p=0.003). Twelve (%60) of the patients developed PEG complications, 6(30%) had their PEG replaced. Those who had developed PEG complications had low levels of albumin (3.3±0.4 vs 4±0.4 g/dl, p=0.022) and vitamin B12 (578±199 vs 1299±533 pg/ml, p=0.007). Conclusions: Even if PEG is applied late, it provides a partial improvement in patients, but the COVID-19 pandemic reversed these benefits and caused an increase in PEG complications. In order for the patient to get the maximum benefit from PEG, close follow-up is essential

Boundary element method for optical force calibration in microfluidic dual-beam optical trap

The potential use of optical forces in microfluidic environment enables highly selective bio-particle manipulation. Manipulation could be accomplished via trapping or pushing a particle due to optical field. Empirical determination of optical force is often needed to ensure efficient operation of manipulation. The external force applied to a trapped particle in a microfluidic channel is a combination of optical and drag forces. The optical force can be found by measuring the particle velocity for a certain laser power level and a multiplicative correction factor is applied for the proximity of the particle to the channel surface. This method is not accurate especially for small microfluidic geometries where the particle size is in Mie regime and is comparable to channel cross section. In this work, we propose to use Boundary Element Method (BEM) to simulate fluid flow within the micro-channel with the presence of the particle to predict drag force. Pushing experiments were performed in a dual-beam optical trap and particlea's position information was extracted. The drag force acting on the particle was then obtained using BEM and other analytical expressions, and was compared to the calculated optical force. BEM was able to predict the behavior of the optical force due to the inclusion of all the channel walls. © 2015 SPIE

The use of dual reciprocity boundary element method in coupled thermoviscoelasticity

A boundary element formulation is presented in a unified form for the analysis of thermoviscoelasticity problems. The formulation contains the thermoelastic material as a special case. The boundary-only nature of boundary element method is retained through the use of particular integral method; where the particular solutions are evaluated with the aid of dual reciprocity approximation. The proposed formulation can be used in both coupled and uncoupled thermoviscoelasticity analyses, and it permits performing the analysis in terms of fundamental solutions of viscoelastodynamics and diffusion (thermal) equation, and eliminates the need for using the complicated fundamental solutions of coupled thermoviscoelasticity. The formulation is performed in Fourier space where any viscoelastic model can be simulated via the correspondence principle. The determination of the response in time space requires the inversion which can be carried out conveniently by using the fast Fourier transform algorithm. For assessment, some sample problems, both uncoupled and coupled, are considered and whenever possible comparisons are given with the exact data. It is found that the formulation developed in the study, even with the simplest base function proposed in literature, may be used reliably in thermoviscoelasticity analysis, at least, for the problems with finite solution domains

Numerical analysis for nonlinear heat transfer problems using DRM

The boundary element method (BEM) proves to be a powerful alternative numerical method for solving non-linear diffusion problems. In the BEM the mesh is generated only on the surface of a 3D body or on the contour if the domain is 2D. In order to impose body forces to the problem a technique called as Dual Reciprocity Method (DRM) was introduced. The DRM allows to transform the domain integrals into the boundary equivalent integrals by expanding the inhomogeneous terms into a set of global approximating basis functions. In this work a numerical routine based on BEM is implemented for solving a non-linear problem and the non-homogeneous terms were dealt by using the DRM. The routine is validated by using a benchmark of a 2D cube model submitted to a thermal load increment