Cell wall thickness and tangential and radial cell diameter of fertilized and irrigated Norway spruce

Abstract

Slits in container wall improve root structure and stem straightness of outplanted Scots pine seedlings

Abstract

Intra-specific variation in cell wall constituents of needle age classes of Pinus sylvestris in relation to soil fertility status in Southwest England

Abstract

Measurement systems in wall production applications

Tässä tutkimuksessa kehitettiin prototyyppi betonielementin dimension mittaus järjestelmästä. Tämä järjestelmä mahdollistaa kolmiulotteisen kappaleen mittauksen. Tutkimuksessa kehitettiin myös stereonäköön perustuva kappaleen mittaus. Prototyyppiä testailin ja tulokset osoittautuivat luotettaviksi. Tutkimuksessa selvitetään ja vertaillaan myös muita lähestymistapoja ja olemassa olevia järjestelmiä kappaleen kolmiuloitteiseen mittaukseen, joita Suomalaiset yhtiöt käyttävät tällä alalla.

Modeling the transport phenomena within arterial wall: porous media approach

The transport of macromolecules, such as low-density lipoprotein (LDL), and their accumulation in the layers of the arterial wall play a critical role in the creation and development of atherosclerosis. Atherosclerosis is a disease of large arteries e.g., the aorta, coronary, carotid, and other proximal arteries that involves a distinctive accumulation of LDL and other lipid-bearing materials in the arterial wall. Over time, plaque hardens and narrows the arteries. The flow of oxygen-rich blood to organs and other parts of the body is reduced. This can lead to serious problems, including heart attack, stroke, or even death. It has been proven that the accumulation of macromolecules in the arterial wall depends not only on the ease with which materials enter the wall, but also on the hindrance to the passage of materials out of the wall posed by underlying layers. Therefore, attention was drawn to the fact that the wall structure of large arteries is different than other vessels which are disease-resistant. Atherosclerosis tends to be localized in regions of curvature and branching in arteries where fluid shear stress (shear rate) and other fluid mechanical characteristics deviate from their normal spatial and temporal distribution patterns in straight vessels. On the other hand, the smooth muscle cells (SMCs) residing in the media layer of the arterial wall respond to mechanical stimuli, such as shear stress. Shear stress may affect SMC proliferation and migration from the media layer to intima. This occurs in atherosclerosis and intimal hyperplasia. The study of blood flow and other body fluids and of heat transport through the arterial wall is one of the advanced applications of porous media in recent years. The arterial wall may be modeled in both macroscopic (as a continuous porous medium) and microscopic scales (as a heterogeneous porous medium). In the present study, the governing equations of mass, heat and momentum transport have been solved for different species and interstitial fluid within the arterial wall by means of computational fluid dynamics (CFD). Simulation models are based on the finite element (FE) and finite volume (FV) methods. The wall structure has been modeled by assuming the wall layers as porous media with different properties. In order to study the heat transport through human tissues, the simulations have been carried out for a non-homogeneous model of porous media. The tissue is composed of blood vessels, cells, and an interstitium. The interstitium consists of interstitial fluid and extracellular fibers. Numerical simulations are performed in a two-dimensional (2D) model to realize the effect of the shape and configuration of the discrete phase on the convective and conductive features of heat transfer, e.g. the interstitium of biological tissues. On the other hand, the governing equations of momentum and mass transport have been solved in the heterogeneous porous media model of the media layer, which has a major role in the transport and accumulation of solutes across the arterial wall. The transport of Adenosine 5´-triphosphate (ATP) is simulated across the media layer as a benchmark to observe how SMCs affect on the species mass transport. In addition, the transport of interstitial fluid has been simulated while the deformation of the media layer (due to high blood pressure) and its constituents such as SMCs are also involved in the model. In this context, the effect of pressure variation on shear stress is investigated over SMCs induced by the interstitial flow both in 2D and three-dimensional (3D) geometries for the media layer. The influence of hypertension (high pressure) on the transport of lowdensity lipoprotein (LDL) through deformable arterial wall layers is also studied. This is due to the pressure-driven convective flow across the arterial wall. The intima and media layers are assumed as homogeneous porous media. The results of the present study reveal that ATP concentration over the surface of SMCs and within the bulk of the media layer is significantly dependent on the distribution of cells. Moreover, the shear stress magnitude and distribution over the SMC surface are affected by transmural pressure and the deformation of the media layer of the aorta wall. This work reflects the fact that the second or even subsequent layers of SMCs may bear shear stresses of the same order of magnitude as the first layer does if cells are arranged in an arbitrary manner. This study has brought new insights into the simulation of the arterial wall, as the previous simplifications have been ignored. The configurations of SMCs used here with elliptic cross sections of SMCs closely resemble the physiological conditions of cells. Moreover, the deformation of SMCs with high transmural pressure which follows the media layer compaction has been studied for the first time. On the other hand, results demonstrate that LDL concentration through the intima and media layers changes significantly as wall layers compress with transmural pressure. It was also noticed that the fraction of leaky junctions across the endothelial cells and the area fraction of fenestral pores over the internal elastic lamina affect the LDL distribution dramatically through the thoracic aorta wall. The simulation techniques introduced in this work can also trigger new ideas for simulating porous media involved in any biomedical, biomechanical, chemical, and environmental engineering applications.

Sphingosine-1-phosphate-evoked invasion of follicular thyroid cancer cells : evidence for the involvement of HIF-Iα, MMP2 and MMP9

Sphingolipids are widely expressed molecules, which traditionally were considered to have majorly structural properties. Nowadays, however, they are implicated in a wide range of different biological processes. The bioactive lipid sphingosine 1-phosphate (S1P) has emerged during the past decade as one of the most studied molecules due to its proliferative and pro-migratory abilities both during normal physiology and in the pathology of a subset of different diseases. Migration and invasion of cancer cells require changes in cell behavior and modulation of the tissue microenvironment. Tumor aggressiveness is markedly enhanced by hypoxia, in which hypoxia inducible transcription factors 1-2α (HIF-1-2α) are activated to promote metabolism, proliferation and migration. Invasion requires degradation of the extracellular matrix (ECM) achieved by several degrading and remodeling enzymes. Matrix metalloproteinases (MMPs) are broadly expressed and well accepted as proteolytic enzymes with essential roles both in normal physiology and in pathology. Previously, S1P was shown to strongly evoke migration of follicular ML-1 thyroid cancer cells. The objective of this study was to further investigate and understand the mechanisms behind this regulation. In the first project it was demonstrated that S1P enhances the expression and activity of HIF-1α. S1P enhanced the expression of HIF-1α by increasing its synthesis and stability. The S1P-increased HIF-1α was mediated via S1P3, Gi/0, PI3K, PKCβI, ERK1/2, mTOR and translation factors p70S6K and eIF4E. Finally, it was shown that HIF-1α mediated S1P-induced migration. The ECM is constituted of a complex and coordinated assembly of many types of proteins. In order to be able to invade, cells need to break down the ECM, therefore several key players in this event were investigated in the second project. S1P increased the secretion and activity of MMP2 and MMP9 via S1P-receptor 1 and 3 and that these MMPs participated in the S1P-facilitated invasion of ML-1 cells. In this interplay, calpains and Rac1 were involved, both of which are crucial players in migration and invasion. The prognosis for some types of thyroid cancer is relatively good. However, there are forms of thyroid cancers, for which there are no treatments or the current available treatments are inefficient. Thus, new medical interventions are urgently needed. In the third project the significance of the S1P-receptor modulating drug FTY720, which is currently used for the treatment of multiple sclerosis (MS), was studied. The effect of FTY720 was tested on several thyroid cancer cell lines, and it inhibited the proliferation and invasion of all cancer cell lines tested. In ML-1 cells, FTY720 attenuated invasion by blocking signaling intermediates important for migration and invasion of the cells. Moreover, FTY720 inhibited the proliferation of ML-1 cells by increasing the expression of p21 and p27, hence, inducing cell arrest in G1 phase of the cell cycle. Thus, it can be suggested that FTY720 could be used in the treatment of thyroid cancer.

Stromal interaction molecule 1 and its role in the regulation, proliferation and protein expression in follicular ML-1 thyroid cancer cells

Calcium (Ca2+) is involved in the regulation of variety of cellular functions including hallmarks of cancer development such as cellular migration and cellular proliferation. Store-operated calcium entry (SOCE) is a central mechanism in cellular calcium signaling and in maintaining the cellular calcium balance. Stromal interaction molecule 1(STIM1) has been identified as an important constituent of SOCE. In this thesis , the STIM1 proteins are studied for their importance in cellular processes and their effects on the expression of S1P1, S1P2, S1P3, VEGFR-2, and TRPC-1 in follicular ML-1 thyroid cancer cells. The results show the importance of STIM1 proteins in SOCE in these cells. The SOCE is significantly reduced in the STIM1 knockdown cells. The results also show the importance of STIM1 proteins in the expression of S1P2 and VEGFR-2 in these cells, as knockdown of STIM1 was shown to upregulate the expression of S1P2 and VEGFR-2. The migration and proliferation is also considerably reduced in the cells in which STIM1 has been knocked down showing the significance of STIM1 in the migration and proliferation in these cells.