Guiding the Prostatic Artery Embolization Procedure With Computational Fluid Dynamics.

Benign prostatic hyperplasia (BPH) is a common disease associated with lower urinary tract symptoms and is the most frequent benign tumor in men. To reduce BPH therapy complications, prostatic artery embolization (PAE) was developed to replace the surgical options. PAE is a minimally invasive technique in which emboli are injected into the prostate arteries (PA), obstructing the blood flow in the hypervascular nodules. In this work, a personalized PAE treatment strategy was proposed using patient-specific computational fluid dynamics (CFD). First, the hemodynamics environment in the iliac arterial tree considering a large network of bifurcations was studied. The results showed complex blood flow patterns in the iliac arterial network. Subsequently, the transport of embolic particulates during PAE for the standard horizontal and hypothetical vertical patient positioning was simulated using Lagrangian particle tracking. Emboli of different sizes were released at various locations across the iliac arterial tree. The emboli entering the PA were mapped back to their initial location to create emboli release maps (ERMs). The obtained ERMs during the standard patient positioning for smaller emboli at certain release locations showed distinct regions in which if the emboli were released within these regions, all of them would reach the PA without nontarget embolization. During the hypothetical vertical patient positioning, the larger emboli formed a larger coherent region in the ERMs. Our patient-specific model can be used to find the best spatial location for emboli injection and perform the embolization procedure with minimal off-target delivery.

The Story of Wall Shear Stress in Coronary Artery Atherosclerosis: Biochemical Transport and Mechanotransduction.

Coronary artery atherosclerosis is a local, multifactorial, complex disease, and the leading cause of death in the US. Complex interactions between biochemical transport and biomechanical forces influence disease growth. Wall shear stress (WSS) affects coronary artery atherosclerosis by inducing endothelial cell mechanotransduction and by controlling the near-wall transport processes involved in atherosclerosis. Each of these processes is controlled by WSS differently and therefore has complicated the interpretation of WSS in atherosclerosis. In this paper, we present a comprehensive theory for WSS in atherosclerosis. First, a short review of shear stress-mediated mechanotransduction in atherosclerosis was presented. Next, subject-specific computational fluid dynamics (CFD) simulations were performed in ten coronary artery models of diseased and healthy subjects. Biochemical-specific mass transport models were developed to study low-density lipoprotein, nitric oxide, adenosine triphosphate, oxygen, monocyte chemoattractant protein-1, and monocyte transport. The transport results were compared with WSS vectors and WSS Lagrangian coherent structures (WSS LCS). High WSS magnitude protected against atherosclerosis by increasing the production or flux of atheroprotective biochemicals and decreasing the near-wall localization of atherogenic biochemicals. Low WSS magnitude promoted atherosclerosis by increasing atherogenic biochemical localization. Finally, the attracting WSS LCS's role was more complex where it promoted or prevented atherosclerosis based on different biochemicals. We present a summary of the different pathways by which WSS influences coronary artery atherosclerosis and compare different mechanotransduction and biotransport mechanisms.

Fluoride concentration of drinking waters and prevalence of fluorosis in iran: a systematic review.

BACKGROUND AND AIMS: The aim of the present study was to systematically review fluoride concentration of drinking waters and prevalence of fluorosis in Iran through systematically evaluating results of studies conducted in this regard. MATERIALS AND METHODS: In this systematic review study, the required data was collected using keywords including drinking water fluoride, fluoride concentration, Fluorosis, dent*, Iran*, and their Persian equivalents through PubMed, ScienceDirect, IranMedex, SID, MEDLIB, and Magiran databases. Out of 617 articles, 29 articles were finally considered after excluding the remaining articles which were not related to the study objectives. Following precise studying and extraction, the relevant data were summarized in extraction tables and analyzed manually. Excel 2007 software was used to draw diagrams. RESULTS: 4434 samples of surface, ground, and tap water resources collected within 236 months during all seasons in 17 provinces of Iran were used in 29 articles determining fluoride concentrations of drinking water. Average fluoride concentration was estimated to be 0.43 ± 0.17 ppm with zero and 3.06 as minimal and maximal values. The least concentration was seen in tap water. Fluoride concentration of only three provinces was in accordance with the global standard. According to estimations, prevalence of fluorosis was 61% with only 1% as severe fluorosis. CONCLUSION: Despite lower than standard concentrations of fluoride in drinking water, a relatively high level of fluorosis was seen in Iran.