Differences In Migration Rates Research Articles

Use microfluidics to study cell migration in response to fluid shear stress gradients

Cells respond not only to biological regulatory factors but also to physical stimuli such as electric fields, light, and shear stress in their environment. These stimuli can lead to cell migration and morphological changes. In the human body, cells encounter fluid shear stress induced by interstitial flow, lymphatic flow, blood flow, or organ-specific conditions within their micro-environments. Therefore, fluid shear stress, a classic mechanical force, has gained significant attention in wound healing and cancer metastasis. In this study, a microfluidic chip was developed to both culture cells and generate a shear stress gradient to direct cell migration. The design of this device’s geometry allows the generation of a shear stress gradient perpendicular to the direction of medium flow. This greatly eliminates the influence of flow-induced cell responses. Using mouse fibroblast cells (NIH3T3) and human lung cancer cells (CL1-5) as models, their migration directionality, migration rates, and alignment in response to the shear stress gradient were investigated. Within the stress range of 0.095–0.155 Pa and a gradient of 0.015 Pa/mm, NIH3T3 cells did not exhibit significant directional migration, differences in migration rates, or specific alignment patterns. In contrast, CL1-5 cells preferred higher shear stress environments and alignment parallel to the medium flow, suggesting that these conditions could induce higher mobility in these cancer cells.

Role of intercellular adhesion molecule-1 in adhesion and migration of mesenchymal stem cells in ankylosing spondylitis and its mechanisms

Objective: To investigate the role and underlying mechanisms of intercellular adhesion molecule-1 (ICAM-1) in the adhesion and migration of mesenchymal stem cells (MSCs) in patients with ankylosing spondylitis (AS). Methods: Bone marrow and ligament tissues were collected during surgery from patients with AS and thoracolumbar fractures (as controls, HC) treated from October 2021 to October 2022 at Nanjing University Medical School Affiliated Nanjing Drum Tower Hospital. MSCs were isolated and cultured from the bone marrow using the Ficoll separation method. Cell morphology was observed under high-resolution microscopy, and differences in the cytoskeletal features between AS-and HC-MSCs were analyzed through immunofluorescence staining. The expression of ICAM-1 was quantified in both groups using real-time quantitative polymerase chain reaction (RT-qPCR) and flow cytometry. Transwell migration assays and wound healing experiments were conducted to evaluate the differences in migration rates between the two groups of MSCs. Results: The interspinous ligament and bone marrow was acquired in AS (2 males and 1 female; 33, 37, 32 years old, respectively) and no-AS patients (2 males and 1 female; 35, 32, 38 years old, respectively). AS-MSCs exhibited broader cell morphology compared to HC-MSCs under bright field and fluorescence microscopy. Immunofluorescence staining of the interspinous ligament showed higher expression of ICAM-1 (68.38±3.42 vs 48.31±2.43) and CD105 (37.97±2.16 vs 23.36±2.06) in AS patients (both P<0.001). Western blot and RT-qPCR analysis revealed significantly stronger protein expression and transcription levels of ICAM-1 in AS-MSCs when compared to those in HC-MSCs (both P<0.001). Flow cytometry confirmed greater mean fluorescence intensity of ICAM-1 in AS-MSCs than in that in HC-MSCs (924.30±54.99 vs 636.47±40.03, P=0.002). Regarding cell adhesion efficiency, it showed no significant difference between AS-MSCs and HC-MSCs in the early stage of adhesion (0.5 h: 1 496±213 vs 1 205±163, P=0.133), but they were all significantly higher in AS-MSCs in the later stage (1 h: 2 894±172 vs 1 908±155, P=0.002; 2 h: 4 540±286 vs 3 334±188, P=0.004; 3 h: 5 212±281 vs 4 208±303, P=0.014). Finally, cell migration experiments demonstrated a stronger migration capability of AS-MSCs compared to HC-MSCs (5 449±172 vs 4 016±155, P<0.001), and the inhibition efficiency of A-205804 on the migration rate of AS-MSCs was stronger than that on HC-MSCs (2 145±239 vs 3 539±316, P=0.004). Conclusions: The aberrant expression of ICAM-1 markedly influences the adhesion and migration dynamics of MSCs. Elevated ICAM-1 levels in MSCs derives from patients with AS significantly enhance their migratory capabilities.

New Trends in Separation Techniques of Lithium Isotopes: A Review of Chemical Separation Methods.

In terms of isotopic technologies, it is essential to be able to produce materials with an enriched isotopic abundance (i.e., a compound isotopic labelled with 2H, 13C, 6Li, 18O or 37Cl), which is one that differs from natural abundance. The isotopic-labelled compounds can be used to study different natural processes (like compounds labelled with 2H, 13C, or 18O), or they can be used to produce other isotopes as in the case of 6Li, which can be used to produce 3H, or to produce LiH that acts like a protection shield against fast neutrons. At the same time, 7Li isotope can be used as a pH controller in nuclear reactors. The COLEX process, which is currently the only technology available to produce 6Li at industrial scale, has environmental drawbacks due to generation of Hg waste and vapours. Therefore, there is a need for new eco-friendly technologies for separation of 6Li. The separation factor of 6Li/7Li with chemical extraction methods in two liquid phases using crown ethers is comparable to that of COLEX method, but has the disadvantages of low distribution coefficient of Li and the loss of crown ethers during the extraction. Electrochemical separation of lithium isotopes through the difference in migration rates between 6Li and 7Li is one of the green and promising alternatives for the separation of lithium isotopes, but this methodology requires complicated experimental setup and optimisation. Displacement chromatography methods like ion exchange in different experimental configurations have been also applied to enrich 6Li with promising results. Besides separation methods, there is also a need for development of new analysis methods (ICP-MS, MC-ICP-MS, TIMS) for reliable determination of Li isotope ratios upon enrichment. Considering all the above-mentioned facts, this paper will try to emphasize the current trends in separation techniques of lithium isotopes by exposing all the chemical separation and spectrometric analysis methods, and highlighting their advantages and disadvantages.

Evaluation of ion transport properties characterizing concentration polarization in membrane-solution system under different factors

Abstract The ion transport properties across the membrane under conditions of different membrane types, solution concentrations, flow rates and temperatures were investigated in a four-compartment reactor. By combining linear sweep voltammetry and chronopotentiometry, the limiting current density (I lim), the ion transition time (τ) and the difference between ion transport numbers in the membrane and the solution (t m–t s) were determined. And the diffusion boundary layer thickness (δ) of the membrane-solution system at steady-state conditions was measured by electrochemical impedance spectroscopy. The results show that the use of Selemion membrane and the increase of solution concentration, flow rate and temperature, I lim and τ increase, t m–t s and δ decrease. This means the concentration polarization of the system is weaker and complete concentration polarization is more difficult to occur. At the same time, I lim, τ and t m–t s are strongly related to solution concentration and temperature, while the diffusion boundary layer thickness is mainly affected by solution concentration and flow rate. Additionally, I lim of anion exchange membranes is larger than that of cation exchange membranes due to the difference in migration rates of anion and cation.

Enhanced ethylene glycol (EG)-blocking property of cation exchange membrane by layered double hydroxides modification for electrodialysis-based reclamation of EG waste fluid

Recycling toxic ethylene glycol (EG) solutions, which act as an inhibitor in the process of deep water gas fields exploitation activities, is an indispensable procedure for saving economic costs and avoid potential environmental hazards. In the recovery process, electrodialysis (ED) is an alternative technology for removing salts from high-saline EG wastewater caused by seawater infiltration. To further reduce the leakage transport of EG during ED desalination, a cation exchange membrane (CEM) layer facing the dilute cell was fabricated by electrodepositing layered double hydroxides (LDHs). Introduction of a LDH-modified layer enabled CEMs to have better EG-blocking properties without affecting cation transport, which was due to dense and hydrophilic transport channels formed by the two-dimensional (2D) lamellar structure of LDHs. This further led to differences in migration rates between hydrated cations and EG molecules. The results of ED desalination tests showed that these modified CEMs reduced the EG leakage content by 81 and 46%, compared with commercial CEMs in high-saline EG solution, with EG content of 20 and 60 wt%, respectively. Therefore, this study provided new insight for the application of CEMs based on LDHs surface modification in the special ED field of EG solution desalination.

Comparison of ureteral stent diameters on ureteral stent-related symptoms: A systematic review and meta-analysis.

Ureteral stents may induce complications that may disrupt the quality of life of patients. Several factors that may cause these symptoms are the design, material, diameter, length, and position of the stent. The impact of its diameter varies among current reports, thus we aimed to compare the symptoms between 6 Fr and 5 Fr or less ureteral stents. A systematic search and screening were performed in the Embase, Medline, and Scopus databases. Eligible studies included randomized controlled trials (RCTs). Cochrane risk of bias tool 2 was used to evaluate the studies. Seven RCTs were included in this review. Urinary symptoms were discussed qualitatively. From the included studies, the use of a relatively smaller stent diameter yielded an overall lower rate of Ureteral Stent Symptom Questionnaire score and urinary symptoms compared to a stent with a larger diameter. There was no significant difference in migration rate (OR: 1.55, 95% CI: 0.67-3.57, P ¼ .31), visual analogue scale (MD: 0.42, 95% CI: 2.04 to 1.20, P ¼ .61), analgesic use duration (MD: 0.06, 95% CI: 1.02 to 0.91, P ¼ .91), and stone-free rate probability (OR: 1.29, 95% CI: 0.48-3.45, P ¼ .62) between patients with 5 Fr or less and 6 Fr ureteral stents. Smaller ureteral stent size is suggested for reducing ureteral stent-related symptoms, without significant differences in the incidence of stent migration, pain, analgesic use, and stone-free rate.

“Who would want to lay down into the permafrost?”: an attempt to explain differences in migration rates, strategies and attitudes in two Russian northern cities

ABSTRACT The macro-level explanations for the massive outflux of the population from the Russian Arctic after 1991 mostly do not account for local differences in out-migration rates. At the same time, these differences can be exceptionally large. This paper uses ethnographic methods to explain significant differences in the rates of population outflux between the cities of Vorkuta and Ukhta, Komi Republic, Russia, which exist despite the very similar history and current social and macroeconomic situation of the two cities. The study indicates differences in attitudes to migration and in-migration strategies among the inhabitants of the two cities. It is suggested that the presence of a large group of inhabitants with the same geographic origin and the same solidarity-promoting occupation in Vorkuta, but not in Ukhta, in the late Soviet period can partly explain this difference. The migration of the members of this group back towards the region of their origin created a migration network with certain cultural norms and expectations related to it; thus, a certain culture of migration emerged. The study points to the potentially significant role of social and cultural factors in shaping the patterns of recent migrations from the Russian Arctic.

Genetic structure of urban and non-urban populations differs between two common parid species

Landscape conversions induced by human activities can affect dispersal patterns of various bird species and, as a result, affect genetic structure of their populations. Genetic differentiation of bird populations may be enhanced by habitat variation, especially in urban-non-urban systems. The majority of population genetic studies focus on single species, which inflicts limitations for direct comparisons of genetic responses of avian populations to urbanization. Here, we used a set of microsatellite markers to examine genetic diversity, gene flow and population structure in two common parid species, great tits Parus major and blue tits Cyanistes caeruleus occupying three sites in habitats with contrasting urbanization level in central Poland. We found low but significant divergence of urban park population with both suburban and non-urban forest great tit populations, while no differentiation was found between suburban forest and non-urban forest populations. In contrast, no evidence for genetic differentiation was found between blue tit populations from the urban park, suburban forest and non-urban forest sites. We conclude that great tits and blue tits respond to urbanization-related changes in a different way, which may be a result of different rates of migration and/or dispersal, likely higher in blue tits. Some impact may be also induced by interspecific competition. We suggest that changing the focus of urban genetic research from single to multiple species may provide novel insights into how natural populations respond to the processes of urbanization.

Out With the Old and in With the New? Factors Involved in Migration of Older and Newer Generation Stereotactic Breast Biopsy Markers.

The purpose of this study was to investigate four commonly used stereotactic biopsy markers, two older and two newer generation, assessing percentage migration and factors influencing migration distance. This was an IRB-approved retrospective review of upright stereotactic breast biopsies from May 2018 to May 2020 involving either older (Cork, Hourglass) or newer (Vision, X-shaped) generation markers. Markers were assessed for migration rate by two-sample Z-test and migration distance by analysis of variance. Univariate analysis was used to assess relationships between marker type and generation, patient characteristics, breast composition and thickness, procedure techniques, trainee involvement, and complications, correlating with migration distance. Multivariable analysis was performed for variables with P-value < 0.1 on univariate analysis. Tukey's test was used to compare groups (P < 0.05). In total, 732 stereotactic biopsies were performed with 508 using a Cork, Hourglass, Vision, or X-shaped marker. Overall migration rate was 181/508 (35.6%) with no difference between markers. Breast thickness and density were negatively associated with migration distance in univariate analysis. Older marker migration distance was greater than newer (2.6 cm vs 1.9 cm, respectively), which was significant after adjusting for breast thickness and density (P = 0.037). Density was a significant factor in migration distance, comparing fatty to nonfatty breasts (P < 0.05) in univariate analysis. No difference in migration rate was seen between the four markers. Vision and X-shaped markers demonstrate lower migration distance than Cork and Hourglass in multivariate analysis. There is an inverse relationship between breast density and marker migration distance.

Stuck At Home? The Drag of Homeownership on Earnings After Job Separation

This note takes a novel approach to study the question of whether housing ownership has negative effects on workers' mobility. While most of the literature has focused on studying differential migration rates between owners and renters, commonly known as "house-lock", we analyze this question from the perspective of differences in earnings.

Abstract 6662: Effects of tumor treating fields (TTFields) on dendritic cells functionality

Abstract Introduction Tumor Treating Fields (TTFields) are a clinically applied anti-neoplastic treatment modality delivered via noninvasive application of low intensity (1-3 V/cm), intermediate frequency (100-500 kHz), alternating electric fields. In this study we evaluated the effects of in vitro TTFields application on dendritic cell (DC) properties that include maturation, phagocytosis, and migration. Methods Bone marrow cells were flushed from the femurs and tibias of 5-7 week old C57BL/6 mice to generate bone marrow-derived DCs. For the DC maturation assay, TTFields treated cancer cells were added at a ratio of 1:1 for 24 h. DC maturation was analyzed using flow cytometry to assess surface expression of major histocompatibility complex class II (MHC II), CD40, and CD80 activation markers. For the phagocytosis assay, CellTrackerTM Deep Red Dye, pre-stained TTFields treated cancer cells were added at a ratio of 1:1 for 2h and phagocytosis by DCs was evaluated using flow cytometry. DC migration assays were performed using a modified Matrigel coated Boyden chamber either with or without C-C Motif Chemokine Ligand 19 (CCL19), utilized as a chemoattractant. Results TTFields treated cancer cells were effectively phagocytosed by DCs, while untreated control cells did not show similar outcomes. In addition, activation markers were found to be upregulated in DCs that were co-cultured with TTFields treated cells. This up-regulation was observed for all the costimulatory molecules analyzed. DC migration assays, showed no significant difference in migration rates between untreated and TTFields treated DCs, with or without the chemoattractant CCL19. Conclusions These in vitro results indicate that TTFields treated cancer cells promote DC elicited phagocytosis and DC maturation. Moreover, in contrast to previous studies reporting that TTFields show an inhibitory effect on cancer cell migration, we demonstrate that TTFields do not impair the migratory properties of DCs. Citation Format: Tali Voloshin, Shiri Davidi, Noa Kaynan, Rosa Schneiderman, Alexandra Volodin, Moshe Giladi, Uri Weinberg, Yoram Palti. Effects of tumor treating fields (TTFields) on dendritic cells functionality [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6662.

Ethno-Caste Influences on Migration Rates and Destinations.

While studies commonly show differences in out-migration between ethnic groups, ethnicity most often features no more than a side note in the emigration literature, and we have very little insight about why people from different ethnic groups migrate at different rates. Understanding ethnic differences in migration rates and destination choice has important implications for the present-day and future potential for either dampening or exacerbating ethnic discrimination and opportunity structures. Building on existing migration theory, we identify three possible mechanisms through which ethnicity might influence out-migration rates and destination choice: human and economic capital, contemporary discrimination, and historical legacies that are perpetuated through social networks. Our empirical investigation uses longitudinal panel survey data from Nepal and we find that all three of these mechanisms likely influence out-migration and destinations of the five major ethno-caste groups. However, we show that historical legacy and human and economic capital emerge as the key drivers of ethnic differences in out-migration here. We discuss what these results mean for migration studies as well as the potential for the institution of migration to affect patterns of ethno-caste-based disadvantage in Nepal. The theoretical basis and empirical evidence from our study also suggest ways to understand the reasoning for and consequence of ethnic and racial differentials in migration patterns in other areas of the world.

A tenfold slowdown in river meander migration driven by plant life

Meandering rivers are diagnostic landforms of hydrologically active planets, and their migration regulates the continental component of biogeochemical cycles that stabilize climate and allow for life on Earth. The rise of river meanders on Earth has been linked to riverbank stabilization driven by the Palaeozoic evolution of plant life about 440 million years ago. Here we provide a fundamental test for this hypothesis using a global analysis of active meander migrations that includes previously ignored unvegetated rivers from the arid interiors of modern continents. When normalized by channel size, unvegetated meanders universally migrate an order of magnitude faster than vegetated ones. While providing irrefutable evidence that vegetation is not required for meander formation, we demonstrate how profoundly vegetation transformed the pace of change for Earth’s landscapes, and we at last offer a mechanistic explanation for the radically distinct stratigraphic records of barren and vegetated rivers. We posit that the migration slowdown driven by the rise of land plants dramatically impacted biogeochemical fluxes and rendered Earth’s landscapes even more hospitable to life. Therefore, the tenfold faster migration of unvegetated rivers may be key to deciphering the environments of barren worlds such as early Earth and Mars. River meanders migrate much faster in barren than in vegetated landscapes, according to global analyses of active meander migration of both unvegetated and vegetated rivers. The difference in migration rates suggests that the rise of land plants had a significant influence on landscapes.

On the Effects of Tip Clearance and Operating Condition on the Flow Structures Within an Axial Turbomachine Rotor Passage

Abstract Effects of tip clearance size and flowrate on the flow around the tip of an axial turbomachine rotor are studied experimentally. Visualizations and stereo-particle image velocimetry (PIV) measurements in a refractive index-matched facility compare the performance, leakage velocity, and the trajectory, growth rate, and strength of the tip leakage vortex (TLV) for gaps of 0.49% and 2.3% of the blade chord, and two flowrates. Enlarging the tip clearance delays the TLV breakup in the aft part of the rotor passage at high flowrates but causes earlier breakup under pre-stall conditions. It also reduces the entrainment of endwall boundary layer vorticity from the separation point where the leakage and passage flows meet. Reducing the flowrate or tip gap shifts the location of the TLV detachment from the blade suction side (SS) upstream to points where the leakage velocity is 70–80% of the tip speed. Once detached, the growth rates of the total shed circulation are similar for all cases, i.e., varying the gap or flowrate mostly shifts the detachment point. The TLV migration away from the SS decreases with an increasing gap but not with the flowrate. Two mechanisms dominate this migration: initially, the leakage jet pushes the TLV away from the blade at 50% of the leakage velocity. Further downstream, the TLV is driven by its image on the other side of the endwall. Differences in migration rate are caused by the smaller distance between the TLV and its image for the narrow gap, and the increase in initial TLV strength with decreasing flowrate and gap.

SOCIAL CHANGES IN IMPRESSIONABLE YEARS AND ADULT POLITICAL ATTITUDES: EVIDENCE FROM JEWISH EXPULSIONS IN NAZI GERMANY

This study provides evidence that individuals who grew up during the 1930's Jewish expulsions are less likely to show interest and participate in politics. The estimates imply that, at the mean, individuals in their impressionable ages at the time of the expulsions are about 13% less likely to be interested in politics and 26% less likely to participate in politics. These results are not found for individuals who were older at the time of the expulsions nor for those growing up during world War (WWII). Results are robust to fixed region and birth‐year characteristics, various definitions of impressionable ages, and composition bias induced by differential migration and mortality rates across regions and cohorts. The estimates are also not driven by other regional differences in 1930's political participation, party support, Catholic share, exposure and destruction during WWII, urbanization, and other regional characteristics. We provide evidence that the adverse effects on political attitudes we find are explained by a model of political participation emphasizing the role of civic skills and socioeconomic status acquired at younger ages. Exposure to the expulsions when young is associated with lower adult volunteerism, trust, church attendance, and socioeconomic status. (JELO12, D72, D74, J15)

Roy-model bounds on the wage effects of the Great Migration

Summary This paper combines a Roy model of migration and counterfactual wages with racial differences in migration rates during the Great Migration to recover lower bounds on black–white differences in the wage impacts of northward migration. Identification is predicated on the idea that, when migration is more selective for whites, regional wage differentials for whites will be more contaminated with selection bias. In this case, the black–white difference in North–South wage differentials bounds the racial difference in wage impacts from below. Furthermore, as long as the impact of migration on whites’ wages is nonnegative, a lower bound on the black–white difference in wage impacts is also a lower bound on the impact itself for blacks. Applying the identification result, I find that northward migration increased blacks’ wages by at least 36% more than whites’, and hence by at least 36%, on average between 1940 and 1970.

Abstract 3703: Development of oncopig urothelial carcinoma cell lines

Abstract Urothelial carcinoma (UC), more commonly known as bladder cancer, affects approximately 81,000 people a year in the United States and is the fourth most common type of cancer among men. Age also plays a tremendous factor, as 90% of people affected by bladder cancer are older than 55, and if the cancer has metastasized the 5-year survival rate is 35%. This requires the advancement of early detection and treatment methods for bladder cancer. The development of clinically relevant systems to serve as a bridge between preclinical murine studies and human clinical practice is of vital importance. The Oncopig Cancer Model (OCM) is a novel transgenic swine platform that recapitulates human cancer through development of site/cell specific tumors after Cre recombinase induced expression of heterozygous KRASG12D and TP53R167H transgene. In this study, we standardized a protocol for the development and growth of Oncopig UC cell lines that faithfully recapitulates in vitro and in vivo features of human bladder cancer. The focus of this preliminary research was to successfully create OCM UC cell lines that mimic features of human UC. OCM urothelial cell lines (n=7) were isolated from whole bladders collected from male Oncopigs at euthanasia. OCM urothelial cell lines were exposed to Cre recombinase 48 hours post isolation to induce expression of KRASG12D and TP53R167H transgenes, resulting in development of OCM UC cell lines. Differences in migration rates were observed between OCM urothelial and UC cell lines, confirming cellular invasiveness. RT-PCR was performed after several passages to confirm KRASG12D and TP53R167H gene expression, which was observed in OCM UC but not urothelial cell lines. Uroplakin II and pan-Cytokeratin (PCK-26) are markers for UC and urothelial cells, respectively, and are used to diagnose UC clinically. OCM UC cells stained positively for Uroplakin II and PCK-26, confirming their identity as malignant UC cells. Future work is needed to confirm OCM and human UC display similar histological and molecular features, and to develop strategies for in vivo OCM UC tumor development. Citation Format: Aisha Qazi, Faith M. Thomas, Sulalita Chaki, Noah Robertson, Shovik Patel, Kyle M. Schachtschneider, Lawrence B. Schook. Development of oncopig urothelial carcinoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3703.

Correlation of composition, cooling rate and superheating temperature with solidification behaviors and microstructures of Al–Bi–Sn ribbons

In this paper, Al85Bi6Sn9, Al75Bi9Sn16, Al60Bi14.4Sn25.6 and Al45Bi19.8Sn35.2 immiscible alloys ribbons were prepared using a single-roller melt-spinning technique. The influences of the composition, the rotating speed of copper roller and the melt superheating temperature were investigated in terms of the thickness, width, phase constitution and microstructures of Al–Bi–Sn ribbons. The results showed that the (Al), (Bi) and (Sn) solid solution phases existed in all the investigated Al–Bi–Sn ribbons. When the rotating speed was larger than 2000 revolutions per minute (rpm), the amorphous phase also was formed. The thickness of ribbons increased and the width decreased with the increase in the aluminum content or with the descent in the melt superheating temperature. The grain sizes of Sn–Bi-rich phase and Al-rich phase decreased gradually with the increases in the rotating speed, the aluminum content or the distance to the free surface. Although there was no obvious macrosegregation under the rapid solidification, the microsegregation still occurred under the rapid solidification. In addition, the grain size of Al75Bi9Sn16 ribbons had a minimum value after the melt superheating treatment at 910 °C. The impact of melt thermal treatment on the microstructure was analyzed from the views of thermodynamics and kinetics. The changes in the grain size and morphology were attributable to the differences in migration rate, solidification rate and the time of liquid-liquid phase separation (L-LPS). The results are conducive for understanding the effects of composition and melt treatment on the microstructures of immiscible alloys.

Abstract A25: Urokinase plasminogen activator expression is regulated by p53 harboring the lung cancer-specific mutation V157F

Abstract Rationale: Cancers of the lung and bronchus are responsible for nearly 30% of all cancer-related deaths in the US, and mutations in the tumor-suppressor gene TP53 occur in 54% of lung adenocarcinomas and 86% of squamous cell carcinomas. Compared with other cancers, TP53 mutational hotspots in lung cancer more often include missense mutations at codons V157, R158, and A159, with frequencies approaching that of the canonical mutational hotspot R273. The resulting mutant p53 (mutp53) protein often exhibits not only loss of tumor suppressor capability but also gain of oncogenic function (GOF). Our previous work identified a novel, p53-dependent transcriptome including alterations in expression of urokinase plasminogen activator (uPA), a key regulator of the plasminogen activation system. When activated, uPA converts plasminogen to plasmin, which cleaves extracellular matrix components and promotes cell migration. We evaluated uPA expression and cell migration in human lung cancer cell lines expressing wild-type or mutant p53. Methods: Human lung cancer cell lines with wild-type p53 (A549) or with somatic mutations at the endogenous p53 locus (NCI-H1781 and NCI-H2087, V157F; NCI-H441, R158L; NCI-H2110, R158P; NCI-H2009, R273L) were obtained from ATCC. Using RNAi (shRNA and siRNA) cells were depleted of p53 as confirmed by puromycin selection of cells infected with lentivirus, in the case of shRNA. Whole-cell lysates were harvested for protein and RNA purification, and conditioned medium was harvested for measurement of secreted proteins. Immunoblotting and qRT-PCR were used to assess expression of protein and mRNA, respectively. A wound healing assay was performed following siRNA transfection to determine cell migration in cells expressing vs. depleted of wild-type or mutant p53. Results: Silencing of p53 by shRNA and siRNA targeted to TP53 was confirmed by Western blot and qRT-PCR. With p53 depletion, protein and mRNA expression of the uPA pro-enzyme pro-uPA and its activated B- and A-chains increased in the H2087 (V157F mutp53) cell line. No p53-dependent change was seen in uPA expression in H2009 cells (R273L mutp53) despite a similar relative quantity of uPA protein. Secreted uPA also increased as measured in conditioned media from H2087 cells (V157F mutp53). A wound healing assay showed increased migration by mutp53-depleted H2087 cells compared with mutp53-expressing H2087 cells, while A549 cells (wt p53) showed no p53-dependent difference in migration rate. Conclusions: To our knowledge, GOF phenotypes in lung cancer cells carrying V157F mutp53 have not been characterized. We have shown here that mutp53 represses uPA expression in human lung cancer cells with endogenous V157F mutp53, and depletion of p53 in these cells leads to an increase in migration. These findings prompt a reexamination of the signaling pathways associated with uPA. Further study is needed to elucidate the mechanism of the p53-dependent alterations in uPA expression and to establish additional biologic effects of V157F mutp53. Citation Format: Julie A. Barta, Steven B. McMahon. Urokinase plasminogen activator expression is regulated by p53 harboring the lung cancer-specific mutation V157F [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr A25.

Migration of Barchan Dunes in Qatar–Controls of the Shamal, Teleconnections, Sea-Level Changes and Human Impact

Barchan dune fields are a dominant landscape feature in SE Qatar and a key element of the peninsula’s geodiversity. The migration of barchan dunes is mainly controlled by dune size, wind patterns, vegetation cover and human impact. We investigate the variability of dune migration in Qatar over a time period of 50 years using high-resolution satellite and aerial imagery. We then explore its relation to the regional Shamal wind system, teleconnection patterns, and limitations in sand supply associated with the transgression of the Arabian Gulf. Strong size-dependent differences in migration rates of individual dunes as well as significant decadal variability on a dune-field scale are detected, which are found to correlate with the intensity of the North Atlantic Oscillation (NAO) and the Indian Summer Monsoon (ISM), in particular during years of relatively strong (weak) summer Shamals. High uncertainties associated with the extrapolation of migration rates back into the Holocene, however, do not permit further examination of the timing of the loss of sand supply and the onset of the mid-Holocene relative sea-level (RSL) highstand. For the youngest phase considered in this study (2006–2015), human impact has likely accelerated dune migration under a weakening Shamal regime through sand mining and excessive vehicle traffic upwind of the core study area.