Mathematical modeling of electro-rotation spectra of small particles in liquid solutions: Application to human erythrocyte aggregates

Electro-rotation can be used to determine the dielectric properties of cells, as well as to observe dynamic changes in both dielectric and morphological properties. Suspended biological cells and particles respond to alternating-field polarization by moving, deforming or rotating. While in linearly polarized alternating fields the particles are oriented along their axis of highest polarizability, in circularly polarized fields the axis of lowest polarizability aligns perpendicular to the plane of field rotation. Ellipsoidal models for cells are frequently applied, which include, beside sphere-shaped cells, also the limiting cases of rods and disks. Human erythrocyte cells, due to their particular shape, hardly resemble an ellipsoid. The additional effect of rouleaux formation with different numbers of aggregations suggests a model of circular cylinders of variable length. In the present study, the induced dipole moment of short cylinders was calculated and applied to rouleaux of human erythrocytes, which move freely in a suspending conductive medium under the effect of a rotating external field. Electro-rotation torque spectra are calculated for such aggregations of different length. Both the maximum rotation speeds and the peak frequencies of the torque are found to depend clearly on the size of the rouleaux. While the rotation speed grows with rouleaux length, the field frequency nup is lowest for the largest cell aggregations where the torque shows a maximum.

Spatial modeling techniques for mapping and characterization of acid sulfate soils

Acid sulfate (a.s.) soils constitute a major environmental issue. Severe ecological damage results from the considerable amounts of acidity and metals leached by these soils in the recipient watercourses. As even small hot spots may affect large areas of coastal waters, mapping represents a fundamental step in the management and mitigation of a.s. soil environmental risks (i.e. to target strategic areas). Traditional mapping in the field is time-consuming and therefore expensive. Additional more cost-effective techniques have, thus, to be developed in order to narrow down and define in detail the areas of interest. The primary aim of this thesis was to assess different spatial modeling techniques for a.s. soil mapping, and the characterization of soil properties relevant for a.s. soil environmental risk management, using all available data: soil and water samples, as well as datalayers (e.g. geological and geophysical). Different spatial modeling techniques were applied at catchment or regional scale. Two artificial neural networks were assessed on the Sirppujoki River catchment (c. 440 km2) located in southwestern Finland, while fuzzy logic was assessed on several areas along the Finnish coast. Quaternary geology, aerogeophysics and slope data (derived from a digital elevation model) were utilized as evidential datalayers. The methods also required the use of point datasets (i.e. soil profiles corresponding to known a.s. or non-a.s. soil occurrences) for training and/or validation within the modeling processes. Applying these methods, various maps were generated: probability maps for a.s. soil occurrence, as well as predictive maps for different soil properties (sulfur content, organic matter content and critical sulfide depth). The two assessed artificial neural networks (ANNs) demonstrated good classification abilities for a.s. soil probability mapping at catchment scale. Slightly better results were achieved using a Radial Basis Function (RBF) -based ANN than a Radial Basis Functional Link Net (RBFLN) method, narrowing down more accurately the most probable areas for a.s. soil occurrence and defining more properly the least probable areas. The RBF-based ANN also demonstrated promising results for the characterization of different soil properties in the most probable a.s. soil areas at catchment scale. Since a.s. soil areas constitute highly productive lands for agricultural purpose, the combination of a probability map with more specific soil property predictive maps offers a valuable toolset to more precisely target strategic areas for subsequent environmental risk management. Notably, the use of laser scanning (i.e. Light Detection And Ranging, LiDAR) data enabled a more precise definition of a.s. soil probability areas, as well as the soil property modeling classes for sulfur content and the critical sulfide depth. Given suitable training/validation points, ANNs can be trained to yield a more precise modeling of the occurrence of a.s. soils and their properties. By contrast, fuzzy logic represents a simple, fast and objective alternative to carry out preliminary surveys, at catchment or regional scale, in areas offering a limited amount of data. This method enables delimiting and prioritizing the most probable areas for a.s soil occurrence, which can be particularly useful in the field. Being easily transferable from area to area, fuzzy logic modeling can be carried out at regional scale. Mapping at this scale would be extremely time-consuming through manual assessment. The use of spatial modeling techniques enables the creation of valid and comparable maps, which represents an important development within the a.s. soil mapping process. The a.s. soil mapping was also assessed using water chemistry data for 24 different catchments along the Finnish coast (in all, covering c. 21,300 km2) which were mapped with different methods (i.e. conventional mapping, fuzzy logic and an artificial neural network). Two a.s. soil related indicators measured in the river water (sulfate content and sulfate/chloride ratio) were compared to the extent of the most probable areas for a.s. soils in the surveyed catchments. High sulfate contents and sulfate/chloride ratios measured in most of the rivers demonstrated the presence of a.s. soils in the corresponding catchments. The calculated extent of the most probable a.s. soil areas is supported by independent data on water chemistry, suggesting that the a.s. soil probability maps created with different methods are reliable and comparable.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Atomic Force Microscopy Investigation of NI Particles Deposited on Porous Silicon

In this thesis properties and influence of modification techniques of porous silicon were studied by Atomic Force Microscope (AFM). This device permits to visualize the surface topography and to study properties of the samples on atomic scale, which was necessary for recent investigation. Samples of porous silicon were obtained by electrochemical etching. Nickel particles were deposited by two methods: electrochemical deposition and extracting from NiCl2 ethanol solution. Sample growth was conducted in Saint-Petersburg State Electrotechnical University, LETI. Kelvin probe force microscopy (KPFM) and Magnetic force microscopy (MFM) were utilized for detailed information about surface properties of the samples. Measurements showed the difference in morphology correlating with initial growth conditions. Submicron size particles were clearly visible on surfaces of the treated samples. Although their nature was not clarified due to limitations of AFM technique. It is expected that surfaces were covered by nanometer scale Ni particles, which can be verified by implication of RAMAN device.

Quantitative evaluation of experimental choroidal neovascularization by confocal scanning laser ophthalmoscopy: fluorescein angiogram parallels heparan sulfate proteoglycan expression

The objective of the present study was to develop a quantitative method to evaluate laser-induced choroidal neovascularization (CNV) in a rat model using Heidelberg Retina Angiograph 2 (HRA2) imaging. The expression of two heparan sulfate proteoglycans (HSPG) related to inflammation and angiogenesis was also investigated. CNV lesions were induced with argon laser in 21 heterozygous Zucker rats and after three weeks a fluorescein angiogram and autofluorescence exams were performed using HRA2. The area and greatest linear dimension were measured by two observers not aware of the protocol. Bland-Altman plots showed agreement between the observers, suggesting that the technique was reproducible. After fluorescein angiogram, HSPG (perlecan and syndecan-4) were analyzed by real-time RT-PCR and immunohistochemistry. There was a significant increase in the expression of perlecan and syndecan-4 (P < 0.0001) in retinas bearing CNV lesions compared to control retinas. The expression of these two HSPG increased with increasing CNV area. Immunohistochemistry demonstrated that the rat retina damaged with laser shots presented increased expression of perlecan and syndecan-4. Moreover, we observed that the overexpression occurred in the outer layer of the retina, which is related to choroidal damage. It was possible to develop a standardized quantitative method to evaluate CNV in a rat model using HRA2. In addition, we presented data indicating that the expression of HSPG parallels the area of CNV lesion. The understanding of these events offers opportunities for studies of new therapeutic interventions targeting these HSPG.

Reversible flow of cholesteryl ester between high-density lipoproteins and triacylglycerol-rich particles is modulated by the fatty acid composition and concentration of triacylglycerols

We determined the influence of fasting (FAST) and feeding (FED) on cholesteryl ester (CE) flow between high-density lipoproteins (HDL) and plasma apoB-lipoprotein and triacylglycerol (TG)-rich emulsions (EM) prepared with TG-fatty acids (FAs). TG-FAs of varying chain lengths and degrees of unsaturation were tested in the presence of a plasma fraction at d > 1.21 g/mL as the source of CE transfer protein. The transfer of CE from HDL to FED was greater than to FAST TG-rich acceptor lipoproteins, 18% and 14%, respectively. However, percent CE transfer from HDL to apoB-containing lipoproteins was similar for FED and FAST HDL. The CE transfer from HDL to EM depended on the EM TG-FA chain length. Furthermore, the chain length of the monounsaturated TG-containing EM showed a significant positive correlation of the CE transfer from HDL to EM (r = 0.81, P < 0.0001) and a negative correlation from EM to HDL (r = -041, P = 0.0088). Regarding the degree of EM TG-FAs unsaturation, among EMs containing C18, the CE transfer was lower from HDL to C18:2 compared to C18:1 and C18:3, 17.7%, 20.7%, and 20%, respectively. However, the CE transfer from EMs to HDL was higher to C18:2 than to C18:1 and C18:3, 83.7%, 51.2%, and 46.3%, respectively. Thus, the EM FA composition was found to be the rate-limiting factor regulating the transfer of CE from HDL. Consequently, the net transfer of CE between HDL and TG-rich particles depends on the specific arrangement of the TG acyl chains in the lipoprotein particle core.

Dermatan sulfate reduces monocyte chemoattractant protein 1 and TGF-β production, as well as macrophage recruitment and myofibroblast accumulation in mice with unilateral ureteral obstruction

Selectins play an essential role in most inflammatory reactions, mediating the initial leukocyte-rolling event on activated endothelium. Heparin and dermatan sulfate (DS) bind and block P- and L-selectin function in vitro. Recently, we reported that subcutaneous administration of DS inhibits colon inflammation in rats by reducing macrophage and T-cell recruitment and macrophage activation. In the present study, we examined the effect of porcine intestinal mucosa DS on renal inflammation and fibrosis in mice after unilateral ureteral obstruction (UUO). Twenty-four adult male Swiss mice weighing 20-25 g were divided into 4 groups: group C (N = 6) was not subjected to any surgical manipulation; group SH (N = 6) was subjected to surgical manipulation but without ureter ligation; group UUO (N = 6) was subjected to unilateral ureteral obstruction and received no treatment; group UUO plus DS (N = 6) was subjected to UUO and received DS (4 mg/kg) subcutaneously daily for 14 days. An immunoblot study was also performed for TGF-β. Collagen (stained area ~3700 µm²), MCP-1 (stained area ~1700 µm²), TGF-β (stained area ~13% of total area), macrophage (number of cells ~40), and myofibroblast (stained area ~1900 µm²) levels were significantly (P < 0.05) higher in the UUO group compared to control. DS treatment significantly (P < 0.05) reduced the content of collagen (stained area ~700 µm²), MCP-1 (stained area ~160 µm²) and TGF-β (stained area ~5% of total area), in addition to myofibroblast (stained area ~190 µm²) and macrophage (number of cells ~32) accumulation in the obstructed kidney. Overall, these results indicate that DS attenuates kidney inflammation by reducing macrophage recruitment, myofibroblast population and fibrosis in mice submitted to UUO.

The cytotoxicity of methacryloxylethyl cetyl ammonium chloride, a cationic antibacterial monomer, is related to oxidative stress and the intrinsic mitochondrial apoptotic pathway

Antibacterial monomers incorporated in dentin bonding systems may have toxic effects on the pulp. Thus, the cytotoxicity of antibacterial monomers and its underlying mechanisms must be elucidated to improve the safety of antibacterial monomer application. The influence of an antibacterial monomer, methacryloxylethyl cetyl ammonium chloride (DMAE-CB), on the vitality of L929 mouse fibroblasts was tested using MTT assay. Cell cycle progression was studied using flow cytometry. Production of intracellular reactive oxygen species (ROS) after DMAE-CB treatment was measured using 2,7-dichlorodihydrofluorescein diacetate staining and flow cytometry analysis. Loss of mitochondrial membrane potential, disturbance of Bcl-2 and Bax expression, as well as release of cytochrome C were also measured using flow cytometry analysis or Western blot to explore the possible involvement of the mitochondrial-related apoptotic pathway. DMAE-CB elicited cell death in a dose-dependent manner and more than 50% of cells were killed after treatment with 30 µM of the monomer. Both necrosis and apoptosis were observed. DMAE-CB also induced G1- and G2-phase arrest. Increased levels of intracellular ROS were observed after 1 h and this overproduction was further enhanced by 6-h treatment with the monomer. DMAE-CB may cause apoptosis by disturbing the expression of Bcl-2 and Bax, reducing the mitochondrial potential and inducing release of cytochrome C. Taken together, these findings suggest that the toxicity of the antibacterial monomer DMAE-CB is associated with ROS production, mitochondrial dysfunction, cell cycle disturbance, and cell apoptosis/necrosis.

BMP-2 and titanium particles synergistically activate osteoclast formation

A previous study showed that BMP-2 (bone morphogenetic protein-2) and wear debris can separately support osteoclast formation induced by the receptor activator of NF-κB ligand (RANKL). However, the effect of BMP-2 on wear debris-induced osteoclast formation is unclear. In this study, we show that neither titanium particles nor BMP-2 can induce osteoclast formation in RAW 264.7 mouse leukemic monocyte macrophage cells but that BMP-2 synergizes with titanium particles to enhance osteoclast formation in the presence of RANKL, and that at a low concentration, BMP-2 has an optimal effect to stimulate the size and number of multinuclear osteoclasts, expression of osteoclast genes, and resorption area. Our data also clarify that the effects caused by the increase in BMP-2 on phosphorylated SMAD levels such as c-Fos expression increased throughout the early stages of osteoclastogenesis. BMP-2 and titanium particles stimulate the expression of p-JNK, p-P38, p-IkB, and P50 compared with the titanium group. These data suggested that BMP-2 may be a crucial factor in titanium particle-mediated osteoclast formation.

Association between indoxyl sulfate and bone histomorphometry in pre-dialysis chronic kidney disease patients

Introduction: Experimental studies have suggested that indoxyl sulfate (IS), a protein-bound uremic toxin, may be involved in the development of renal osteodystrophy. Objective: evaluate the association between IS levels and biochemical parameters related to mineral metabolism and bone histomorphometry in a cohort of pre-dialysis chronic kidney disease (CKD) patients. Methods: This is a post-hoc analysis of an observational study evaluating the association between coronary calcification and bone biopsy findings in 49 patients (age: 52 ± 10 years; 67% male; estimated glomerular filtration rate: 36 ± 17 ml/min). Serum levels of IS were measured. Results: Patients at CKD stages 2 and 3 presented remarkably low bone formation rate. Patients at CKD stages 4 and 5 presented significantly higher osteoid volume, osteoblast and osteoclast surface, bone fibrosis volume and bone formation rate and a lower mineralization lag time than CKD stage 2 and 3 patients. We observed a positive association between IS levels on one hand and the bone formation rate, osteoid volume, osteoblast surface and bone fibrosis volume on the other. Multivariate regression models confirmed that the associations between IS levels and osteoblast surface and bone fibrosis volume were both independent of demographic and biochemical characteristics of the study population. A similar trend was observed for the bone formation rate. Conclusion: Our findings demonstrated that IS is positively associated with bone formation rate in pre-dialysis CKD patients.

Veden puhdistus mikro-organismisovelluksilla (EM Mudball®)

Vesistöjen rehevöityminen on maailmanlaajuinen ongelma. ”Effective microorganisms (EM)” -teknologian väitetään mahdollistavan ravinteiden poiston vesistä luonnonmukaisten mikro-organismien avulla. Työn tavoitteena on selvittää kyseistä teknologiaa hyödyntävien EM-mutapallojen soveltuvuutta suomalaisten luonnonvesien sekä jätevesien ravinteiden poistamiseen. Kirjallisuusosassa selitettiin EM-teknologian toimintaperiaate sekä esitettiin EM-mutapallojen koostumus. Tässä osassa selvitettiin myös teknologian käyttökohteita. Lisäksi perehdyttiin Suomen vesistöjen tilanteeseen sekä EM-teknologian mahdollisiin hyödyntämiskohteisiin. Kokeellisessa osassa seurattiin 6 eri vesinäytteen ravinnepitoisuuksien muutosta EM-mutapallon käytön aikana. Osaa näytteistä säilytettiin jääkaapissa, jotta päästiin lähemmäs Suomessa vallitsevia olosuhteita. Analysoidut ravinteet olivat nitraatti, sulfaatti, fosfaatti ja typpi. Tuloksien mukaan EM-mutapallojen käyttö poisti pääsääntöisesti vesinäytteistä nitraatin. Sulfaatin poisto sen sijaan oli huomattavasti heikompaa. Paria näytettä lukuun ottamatta sulfaattipitoisuudet eivät laskeneet lähtökonsentraation alle, vaikka ajoittaista laskua tapahtuikin. Fosfaattipitoisuudet näytteissä olivat yleisesti hyvin pieniä, eivätkä ylittäneet määritysrajaa kokeen aikana ollenkaan. Ainoastaan fosfaattia sisältäneessä synteettisessä näytteessä tapahtui fosfaattipitoisuuden laskua, joka kuitenkin palautui lähes alkuperäiselle tasolle koejakson lopussa. Näytteiden typpipitoisuuksien kasvun aiheutti käymistuotteena muodostuva ammonium, jonka takia myös näytteiden pH nousi. Kokeet vahvistavat aiempia tutkimustuloksia, joiden mukaan EM-mutapallo hajoaa kahden viikon kuluttua niiden lisäämisestä vesinäytteisiin. Aikaisemmista tutkimuksista poiketen tämän kokeen mukaan EM-mutapallot näyttäisivät toimivan paremmin viileämmässä lämpötilassa. Kokeen perusteella EM-teknologian hyödyntäminen voisi olla potentiaalinen vaihtoehto tulevaisuudessa Suomen vesistöjen nitraatin poistoon.