Determining the Size Dependence of Colloidal Gold Nanoparticle Uptake in a Tumor-like Interface (Hypoxic)

AbstractColloidal gold nanoparticles (GNPs) are being used as drug delivery vehicles and radiation dose enhancers in cancer therapy. Oxygen concentration in human tumours is highly heterogeneous with many regions at very low levels of oxygen (hypoxia). A majority of tumours contain regions with oxygen pressure values of less than 0.7% in the gas phase. The purpose of this study was to investigate how the size of the NPs affects their uptake process in a tumour-like hypoxic environment. We used GNPs of diameter 15, 50, and 74nm, and carried out our experiment under 0.2% (hypoxic) and 21% (normoxic) oxygen levels using MCF-7 and HeLa cells. Our results showed that NPs of size 50nm had the highest uptake following prolonged exposure to hypoxia. There was no significant toxicity introduced by NPs under hypoxic conditions. These findings will play a vital role in the optimization of GNP-based therapeutics in cancer treatment

Body numerical phantoms for estimating soft tissue pains or injuries when interacting with shoes, seats and mattresses

International audienc

Influence of the calcaneus shape on the risk of posterior heel ulcer using 3D patient-specific biomechanical modeling.

International audienceMost posterior heel ulcers are the consequence of inactivity and prolonged time lying down on the back. They appear when pressures applied on the heel create high internal strains and the soft tissues are compressed by the calcaneus. It is therefore important to monitor those strains to prevent heel pressure ulcers. Using a biomechanical lower leg model, we propose to estimate the influence of the patient-specific calcaneus shape on the strains within the foot and to determine if the risk of pressure ulceration is related to the variability of this shape. The biomechanical model is discretized using a 3D Finite Element mesh representing the soft tissues, separated into four domains implementing Neo Hookean materials with different elasticities: skin, fat, Achilles' tendon, and muscles. Bones are modelled as rigid bodies attached to the tissues. Simulations show that the shape of the calcaneus has an influence on the formation of pressure ulcers with a mean variation of the maximum strain over 6.0 percentage points over 18 distinct morphologies. Furthermore, the models confirm the influence of the cushion on which the leg is resting: a softer cushion leading to lower strains, it has less chances of creating a pressure ulcer. The methodology used for patient-specific strain estimation could be used for the prevention of heel ulcer when coupled with a pressure sensor

DESAIN SISTEM MONITORING TERNAK SAPI BERBASIS JARINGAN SENSOR NIRKABEL UNTUK SISTEM PENGGEMBALAAN LEPAS DI TIMOR BARAT PROVINSI NUSA TENGGARA TIMUR

Model sistem peternakan yang masih dijumpai khususnya di wilayah Timor Barat yakni sistem ternak lepas berdasar pada budaya masyarakat yakni keterkaitan yang kuat antara manusia, hewan, dan hutan sehingga sulit dihilangkan. Akan tetapi, Model ini memiliki sisi lain yang dapat merugikan bagi tutupan hutan karena berdampak pada lambatnya pertumbuhan biofisik hutan. Dampak negatif lainnya yakni pemilik ternak tidak mampu mengontrol dan memonitoring ternak yang dilepas di hutan sehingga banyak terjadi kasus pencurian, selain kondisi kesehatan ternak sapi yang tidak bisa termonitor. Hal lain yang menguatkan sistem ternak lepas tidak bisa dihilangkan adalah terbatasnya ketersediaan pakan oleh petani apabila diikat, selain kurangnya tenaga kerja. Mengatasi kedua permasalahan pokok ini, yakni di satu sisi sistem lepas tidak bisa dihilangkan, sedangkan di sisi lain sistem lepas memiliki dampak yang merugikan bagi lingkungan dan pemilik, maka diperlukan suatu metode monitoring dan pelacakan keberadaan ternak sapi ketika dilepas di area penggembalaan, dengan menggunakan Teknologi Informatika, berbasis sensor dan GPS (Jaringan Sensor Nirkabel). Pemantauan jarak jauh terhadap perilaku hewan di lingkungan dapat membantu mengelola hewan dan dampak lingkungannya. Kerah GPS yang merekam lokasi hewan dengan frekuensi temporal tinggi memungkinkan untuk memantau perilaku hewan dan interaksi dengan lingkungan. Sensor nirkabel ini dapat dikombinasikan dengan citra satelit yang dapat diamati dari jarak jauh untuk memahami interaksi lingkungan dengan hewan. Sistem monitoring ternak sapi berbasis jaringan sensor nirkabel dapat diterapkan pada system peternakan sapi yang umumnya dilakukan oleh masyarakat di Pulau Timor yakni sistem ternak lepas (ekstensif tradisional)

A CAD-BASED CONCEPTUAL METHOD FOR SKULL PROSTHESIS MODELLING

The geometric modeling of a personalized part of the tissue built according to individual morphology is an essential requirement in anatomic prosthesis. A 3D model to fill the missing areas in the skull bone requires a set of information sometimes unavailable. The unknown information can be estimated through a set of rules referenced to a similar yet known set of parameters of the similar CT image. The proposed method is based on the Cubic Bezier Curves descriptors generated by the de Casteljou algorithm in order to generate a control polygon. This control polygon can be compared to a similar CT slice in an image database. The level of similarity is evaluated by a meta-heuristic fitness function. The research shows that it is possible to reduce the amount of points in the analysis from the original edge to an equivalent Bezier curve defined by a minimum set of descriptors. A study case shows the feasibility of method through the interoperability between the prosthesis descriptors and the CAD environment

Repurposing rapid diagnostic tests to detect falsified vaccines in supply chains

Substandard (including degraded) and falsified (SF) vaccines are a relatively neglected issue with serious global implications for public health. This has been highlighted during the rapid and widespread rollout of COVID-19 vaccines. There has been increasing interest in devices to screen for SF non-vaccine medicines including tablets and capsules to empower inspectors and standardise surveillance. However, there has been very limited published research focussed on repurposing or developing new devices for screening for SF vaccines. To our knowledge, rapid diagnostic tests (RDTs) have not been used for this purpose but have important potential for detecting falsified vaccines. We performed a proof-in-principle study to investigate their diagnostic accuracy using a diverse range of RDT-vaccine/falsified vaccine surrogate pairs. In an initial assessment, we demonstrated the utility of four RDTs in detecting seven vaccines. Subsequently, the four RDTs were evaluated by three blinded assessors with seven vaccines and four falsified vaccines surrogates. The results provide preliminary data that RDTs could be used by multiple international organisations, national medicines regulators and vaccine manufacturers/distributors to screen for falsified vaccines in supply chains, aligned with the WHO global ‘Prevent, Detect and Respond’ strategy

A new model for molecule exchange in the brain microvascular system: consequences of capillary occlusions in Alzheimer's disease

The brain microvascular system is a key actor in Alzheimer’s disease (AD) development. Indeed, a significant decrease of cerebral blood flow is the earliest biomarker of AD. In vivo TPLSM of cortical vasculature in APP/PS1 mice suggests the mechanism underlying the blood flow reduction is capillary occlusions. Leucocytes adhere to inflamed vessel walls and limit the flow. The impact of capillary occlusions on blood flow has been quantified numerically in large (>10000 vessels) anatomical networks in humans and mice. The regional blood flow has been found to depend linearly with no threshold effect on the fraction of capillary occlusions, so that a small fraction of stalls (2-4%) yields a significant decrease in blood flow (5-12%). Such flow decrease has a strong impact on nutrient delivery and waste clearance. That is why we devised a new model to study the effect of capillary stalling on molecule transport. The geometry of anatomical networks is too complex to use classic numerical approaches like finite elements. Instead, our model, inspired by pore-network approaches, reduces computational costs while capturing most of the underlying physics. To derive this model, we apply upscaling methods to the 3D transport equations within each vessel to obtain 1D average equations along the axis. Contrary to previous models, this new formulation describes accurately radial concentration gradients, capturing effects like longitudinal dispersion. We further use a Green’s function formulation to calculate the concentration fields inside the tissue where diffusion and reaction occur. The coupling between vessels and tissues is modelled using a membrane condition representing the blood brain barrier. This new molecule transport model is coupled with our previously validated blood flow model to examine the effects of capillary stalling on molecular exchange in transient and stationary regimes in anatomical networks. In particular, in stationnary regimes, we demonstrate an increase of the extraction coefficient with the proportion of stalled capillaries, which does not compensate for the associated blood flow reduction