Transforming growth factor-β superfamily, implications in development and differentiation of stem cells

Transforming growth factor-β (TGF-β) family members, including TGF-βs and bone morphogenetic proteins (BMPs), play important roles in directing the fate of stem cells. In embryonic stem cells, the TGF-β superfamily participates in almost all stages of cell development, such as cell maintenance, lineage selection, and progression of differentiation. In adult mesenchymal stem cells (MSCs), TGF-βs can provide competence for early stages of chondroblastic and osteoblastic differentiation, but they inhibit myogenesis, adipogenesis, and late-stage osteoblast differentiation. BMPs also inhibit adipogenesis and myogenesis, but they strongly promote osteoblast differentiation. The TGF-β superfamily members signal via specific serine/threonine kinase receptors and their nuclear effectors termed Smad proteins as well as through non-Smad pathways, which explain their pleiotropic effects in self-renewal and differentiation of stem cells. This review summarizes the current knowledge on the pleiotropic effects of the TGF-β superfamily of growth factors on the fate of stem cells and also discusses the mechanisms by which the TGF-β superfamily members control embryonic and MSCs differentiation

Autonomous vehicle lane keeping by analyzing information from visual sensors using a neural network

Cilj disertacije je ostvarivanje autonomnog održanja vozila u kolovoznoj traci analizom informacija sa vizuelnih senzora korišćenjem projektovane duboke neuralne mreže, eng. deep neural network (DNN). DNN za učenje od-kraja-do-kraja na ulaz dovodi sliku sa kamere montirane na vozilu, a izlaz iz DNN je informacija o uglu okretanja upravljača vozila. Ova tehnika se još naziva i kloniranje ponašanja vozača, eng. behavior cloning. Polazna hipoteza je da je moguće ostvariti autonomnu vožnju korišćenjem duboke neuralne mreže za učenje od-kraja-do-kraja koja je računarski manje zahtevna od do sada postojećih rešenja, pri čemu korišćenjem modela nove mreže, performanse autonomne vožnje ne degradiraju značajno. Osnovna prednost novog rešenja je omogućavanje implementacije projektovanog rešenja na autonomno vozilo sa ograničenim hardverskim performansama u smislu računarske snage i memorijskog kapaciteta. Razvijena je nova arhitektura DNN za učenje od-kraja-do-kraja za autonomnu vožnju koja je nazvana J-Net. U poređenju sa drugim poznatim modelima, PilotNet i AlexNet, J-Net model ima najmanji broj trenarabilnih parametara, najmanji broj operacija nad čvorovima neuralne mreže i istrenirana J-Net mreža zauzima najmanje memorijskog prostora. Verifikacija autonomne vožnje ostvarena je u simuliranim uslovima, korišćenjem simulatora autonomne vožnje otvorenog koda, i u realnim uslovima. Za verifikaciju u realnim uslovima, projektovan je sistem za autonomnu vožnju u laboratoriji za elektroniku Elektrotehničkog fakulteta Univerziteta u Beogradu. Verifikacije u simuliranim i u realnim uslovima pokazale su da je korišćenjem J-Net modela duboke neuralne mreže za učenje od-kraja-do-kraja moguće ostvariti uspešno održanje vozila u kolovoznoj traci analizom informacija sa vizuelnih senzora.The aim of the dissertation is to achieve autonomous lane keeping by analyzing information from visual sensors using the designed deep neural network (DNN). DNN for end-to-end learning has a camera image as an input and the steering angle of the vehicle as an output. This technique is also called behavior cloning. The starting hypothesis was that it is possible to achieve autonomous driving using a deep neural network for end-to-end learning that is less computationally demanding than the existing solutions, whereby using a new network model, autonomous driving performance does not degrade significantly. The main advantage of the new solution is enabling the implementation of the designed solution on an autonomous vehicle with limited hardware performance in terms of computing power and memory capacity. A new DNN for end-to-end learning architecture for autonomous driving has been developed, it is called J-Net. Compared to other known models, PilotNet and AlexNet, the J-Net model has the least number of trainable parameters, the least number of operations of neural network nodes, and the trained J-Net network occupies the least memory space. Verification of autonomous driving achieved in simulated conditions, using an open-source simulator for autonomous driving, and in real-world conditions. For the verification in real-world conditions, an autonomous driving system was designed and implemented in the Laboratory of Electronics at the School of Electrical Engineering, University of Belgrade. Verifications in both simulated and real-world conditions have shown that it is possible to achieve successful autonomous lane-keeping by analyzing information from visual sensors using the J-Net DNN model

Skip regulates TGF- β 1-induced extracellular matrix degrading proteases expression in human PC-3 prostate cancer cells

Purpose. To determine whether Ski-interacting protein (SKIP) regulates TGF-β1-stimulated expression of urokinase-type plasminogen activator (uPA), matrix metalloproteinase-9 (MMP-9), and uPA Inhibitor (PAI-1) in the androgen-independent human prostate cancer cell model. Materials and Methods. PC-3 prostate cancer cell line was used. The role of SKIP was evaluated using synthetic small interference RNA (siRNA) compounds. The expression of uPA, MMP-9, and PAI-1 was evaluated by zymography assays, RT-PCR, and promoter transactivation analysis. Results. In PC-3 cells TGF-β1 treatment stimulated uPA, PAI-1, and MMP-9 expressions. The knockdown of SKIP in PC-3 cells enhanced the basal level of uPA, and TGF-β1 treatment inhibited uPA production. Both PAI-1 and MMP-9 production levels were increased in response to TGF-β1. The ectopic expression of SKIP inhibited both TGF-β1-induced uPA and MMP-9 promoter transactivation, while PAI-1 promoter response to the factor was unaffected. Conclusions. SKIP regulates the expression of uPA, PAI-1, and MMP-9 stimulated by TGF-β1 in PC-3 cells. Thus, SKIP is implicated in the regulation of extracellular matrix degradation and can therefore be suggested as a novel therapeutic target in prostate cancer treatment. © 2013 Victor Villar et al

Effects of interleukin-17 on mesenchymal and endothelial cell functions and mechanisms involved

Interleukin (IL) 17 familija citokina se smatra najmanje istraženom citokinskom familijom sa značajnom ulogom u procesu inflamacije. Ubikvitarna rasprostranjenost receptora za IL-17 omogućava ovom citokinu mnogobrojne biološke efekte u organizmu, poput važne uloge u imunskom odgovoru i regulaciji procesa hematopoeze, ali i u progresiji različitih bolesti, uključujući inflamatorna, autoimunska i maligna oboljenja. IL-17 ima ulogu u ćelijskim procesima poput proliferacije i diferencijacije, i to prvenstveno na hematopoetskim matičnim i progenitor ćelijama, pri čemu IL-17 ispoljava različite efekte na proliferaciju i diferencijaciju zavisno od tipa ćelijske loze i stepena diferencijacije ćelija. Takoñe, zbog ubikvitarne rasprostranjenosti svog receptora, IL-17 je uključen u interakcije izmeñu imunskog sistema i somatskih tkiva. Novija istraživanja su pokazala da IL-17 ima i ulogu finog regulatora diferencijacije mezenhimskih matičnih ćelija (MSC, Mesenchymal stem cells), s obzirom na to da stimuliše osteogenu diferencijaciju dok, s druge strane, inhibira adipogenu diferencijciju humanih MSC. Savremena istraživanja biologije MSC ukazala su na širok opseg njihove potencijalne terapijske primene, prvenstveno u regenerativnoj medicini, jer ove multipotentne adultne matične ćelije koje predstavljaju nediferencirane ćelije sa sposobnošću samoobnove, imaju sposobnost diferenciranja u ćelije tkiva mezenhimskog porekla, poput osteoblasta, hondroblasta i adipocita, a prema saznanjima koja imamo danas, i u ćelije tkiva ektodermalnog i endodermalnog porekla. Matične ćelije različitog stepena multipotentnosti izolovane su iz raznih adultnih tkiva, kao i perinatalnih tkiva koja se poslednjih godina sve češće pominju kao povoljan izvor MSC. Meñutim, i pored velikog napretka u ovoj oblasti, nema konačnih saznanja kako o mehanizmima odgovornim za regulaciju višestrukih funkcija MSC, tako i o njihovom ukupnom terapijskom potencijalu. Kako biološke funkcije MSC umnogome zavise od konteksta mikrosredine, ispitivanje interakcija MSC i IL-17 u održavanju multipotentnosti, mobilizaciji i usmerenoj diferencijaciji MSC je od posebnog značaja. Pored mezenhimskih ćelija, IL-17 ostvaruje svoje efekte delovanjem na endotelske ćelije. Jedan od terapijskih ciljeva u regenerativnoj medicini, koji je još uvek nedovoljno objašnjen, je i podsticanje revaskularizacije oštećenog tkiva. Stimulacija postojećih, in situ prisutnih endotelskih ćelija na angiogenezu je jedan od mogućih mehanizama. Efekti IL-17 na endotelske ćelije nisu do sada u potpunosti opisani, i poznato je samo da IL-17 u prisustvu drugih poznatih angiogenih faktora stimuliše sposobnost endotelskih ćelija za angiogenezu. Pored toga, poznato je da se funkcije ćelija kao i delovanje citokina značajano razlikuju u zavisnosti od procenta kiseonika prisutnog u mikrosredini ćelija. Efekat delovanja IL-17 na endotelske ćelije u prisustvu različitih koncentracija kiseonika do sada nije istraživan. Takoñe je još uvek nepoznato da li IL-17 može uticati na diferencijaciju MSC u endotelske ćelije. Da bi se sprovela istraživanja u ovom pravcu, neophodno je uspostaviti pogodan model za diferencijaciju MSC u endotelske ćelije Cilj istraživanja ove disertacije bilo je ispitivanje efekata IL-17 na različite ćelijske funkcije mezenhimskih i endotelskih ćelija u specifičnim uslovima mikrosredine. Analizirano je dejstvo IL-17 na proliferaciju, migraciju, angiogenezu i diferencijaciju ćelija. Istraživani su i molekularni mehanizmi koji omogućavaju finu regulaciju ćelijskih funkcija od strane IL-17, analizom aktivacije signalnih molekula, kao i ekspresije gena i proteina neophodnih za specifične funkcije. Posebna pažnja u istraživanjima bila je posvećena izolaciji, karakterizaciji i endotelskoj diferencijaciji primarnih MSC iz tkiva pupčanika (UC-MSC, Umbilical cord-mesenchymal stem cells). U okviru razjašnjavanja efekata i mehanizama delovanja IL-17 na diferencijaciju mezenhimskih ćelija, primenjena je multipotentna mišja C2C12 ćelijska linija. Uticaj IL-17 na diferencijaciju analiziran je na osnovu ekspresije gena i proteina specifičnih za odreñeni tip diferencijacije: teškog lanca miozina (MyHC, Myosin heavy chain) i miogenina za miogenu, a alkalne fosfataze (ALP, Alkaline phosphatase), Runx2/Cbfa1 (Runt-related transcription factor 2/Core-binding factor subunit alpha-1) transkripcionog faktora i ciklooksigenaze 2 (Cox-2, Cyclooxygenase 2) za osteogenu diferencijaciju. Pored toga, utvrñivano je učešće mitogenom aktiviranih protein kinaza (MAPK) i morfogenetskih proteina kosti (BMP, Bone morphogenic proteins) u IL-17-usmerenoj diferencijaciji C2C12 ćelija. Rezultati su pokazali da IL-17 inhibira miogenu i stimuliše osteogenu diferencijaciju C2C12 ćelija, s obzirom na to da je IL-17-zavisna inhibicija miogeneze povezana sa redukcijom ekspresije iRNK za miogenin, redukcijom ekspresije MyHC i izostankom formiranja miotuba, dok je IL-17-zavisna indukcija osteogeneze povezana sa indukcijom ekspresije iRNK za Runx2/Cbfa1, indukcijom ekspresije Cox-2 i povišenom aktivnošću ALP. Rezultati su takoñe pokazali da IL-17 ostvaruje ove efekte putem aktivacije ERK1,2 MAPK signalnog puta, nezavisno od BMP-Smad signalnog puta. U drugom delu ove studije ispitivan je efekat IL-17 na funkcije endotelskih ćelija na modelu humane endotelske ćelijske linije, EA.hy 926, praćenjem njihove proliferacije, migracije i tubulogeneze u uslovima normoksije i hipoksije. Analizirana je i ekspresija gena za endotelsku azot monoksid sintazu (eNOS, Endothelial nitric oxide synthase) i Cox-2, kao i njihovih proteinskih produkata, budući da ovi molekuli imaju važnu ulogu u procesu angiogeneze. Dobijeni rezultati su potvrdili da IL-17 stimuliše ključne funkcije uključene u proces angiogeneze EA.hy 926 ćelija, poput ćelijske migracije i tubulogneze, kao i ekspresiju eNOS i Cox-2 u ovim ćelijama. Pro-angiogeni efekti IL-17 su pokazani u uslovima normoksije (20% O2). Uslovi hipoksije (3% O2) pokazali su toksično dejstvo na ovu ćelijsku liniju, dok je IL-17 u ovakvim uslovima umanjio broj apoptotičnih ćelija. U okviru trećeg dela ove disertacije MSC su izolovane iz vezivnog tkiva pupčanika, tzv. Vartonove sluzi, umnožene i okarakterisane prema važećim preporukama i kriterijumima Meñunarodnog društva za ćelijsku terapiju. Zatim je ispitan i odreñen optimalni protokol za njihovu efikasnu diferencijaciju u endotelske ćelije, u cilju uspostavljanja novog ćelijskog modela za buduća istraživanja. Princip diferenciranja UC-MSC u endotelske ćelije zasnivao se na inhibiciji signalizacije faktora transformacije rasta (TGF-β, Transforming growth factor beta), i to njegovog receptora, aktivinu-nalik kinaze 5 (ALK5, Activin-like kinase). Na osnovu dobijenih rezultata, zaključeno je da se UC-MSC odlikuju visokom sposobnošću samoobnove i visokim kapacitetom za diferencijaciju kao i da se mogu diferencirati u endotelske ćelije putem inhibicije ALK5 receptoraInterleukin (IL) 17 cytokine family is considered the least explored cytokine family with an important role in inflammation. Due to the ubiquitous expression of its receptor, IL-17 has been implicated in interactions between the immune system and somatic tissues. In this context, recent findings have shown that IL-17 acts as a fine regulator of mesenchymal stem cell (MSC) differentiation. Having in mind that behaviour of MSC depends on the surrounding microenvironment, it is important to analyze the interactions between MSC and IL-17 involved in the maintenance of their multipotency, mobilization and directed differentiation. In addition to mesenchymal cells, IL-17 exerts its roles by acting on endothelial cells as well. Even though IL-17’s effects on endothelial cells have not been fully discovered yet, it is well known that IL- 17, in the presence of other angiogenic factors, has the ability to stimulate endothelial cells to undergo angiogenesis. Furthermore, it is well known that cellular functions, as well as cytokine effects can be significantly modulated by the percentage of oxygen present in their microenvironment. However, effects of IL-17 on endothelial cells in the context of different O2 concentrations have not been explored yet. Also, it is still unknown whether IL-17 can affect endothelial differentiation of MSC, but to address this issue, it is necessary to create a valid model of endothelial differentiation of MSC. The objective of this study was to investigate the effects of IL-17 on different functions of mesenchymal and endothelial cells in specific microenvironmental conditions. The influence of IL-17 on proliferation, migration, angiogenesis and differentiation was analyzed, as well as the molecular mechanisms involved. The activation of various signaling molecules and the expression of genes and proteins involved in specific functions were examined. Yet another objective was to establish an appropriate model for the mesenchymal-endothelial transdifferentiation. For this task primary MSC from umbilical cord tissue (UC-MSC) were isolated and characterized with emphases on their endothelial differentiation. In order to elucidate the effects and mechanisms involved in IL-17 acting on mesenchymal cell differentiation, a multipotent mouse C2C12 cell line was used. The influence of IL-17 on cell differentiation was analyzed based on the expression of genes and proteins specific for the certain type of differentiation: Myosin heavy chain (MyHC) and Myogenin for myogenic, and Alkaline phosphatase (ALP), Runt-related transcription factor 2/Core-binding factor subunit alpha-1 (Runx2/Cbfa1) and Cyclooxygenase-2 (Cox-2) for osteogenic differentiation. Additionaly, the involvement of Mitogen-activated protein kinases (MAPK) and Bone morphogenetic proteins (BMP) in IL-17-directed differentiation of C2C12 cells was investigated. Results obtained demonstrated that IL-17 inhibits myogenic and stimulates osteogenic differentiation of C2C12 cells, by down-regulating the Myogenin mRNA expression, MyHC expression and myotube formation, while up-regulating the Runx2/Cbfa1 mRNK expression, Cox- 2 expression and ALP activity. IL-17 exerted these effects by activating ERK1,2 MAPK signaling pathway, which in turn regulated the expression of relevant genes and proteins to inhibit myogenic differentiation and induce osteogenic differentiation. It was also shown that the induction of osteogenic differentiation by IL-17 is independent of the BMP-Smad signaling pathway. In the second part of this study the effect of IL-17 on endothelial cell functions was investigated using human endothelial cell line EA.hy 926 as a model. The changes in cells’ proliferation, migration and tubulogenesis were analyzed, along with the expression of genes for endothelial Nitric oxide synthase (eNOS) and Cox-2, and their corresponding protein products, since these molecules have important roles in angiogenesis. The influence of the environmental stimuli (normoxia vs. hypoxia) was also investigated. Results obtained demonstrated that IL-17 stimulates crutial events involved in angiogenesis of EA.hy 926 cells, such as cell migration and tubulogenesis, along with the expression of eNOS and Cox-2. However, the effects of IL-17 were dependent on the O2 concentration, since pro-angiogenic effects of IL-17 were noticed in the presence of 20% O2, while 3% O2 exerted toxic effect on this cell line, and IL-17 in these conditions decreased the number of apoptotic cells. In the final task, MSC were isolated from the umbilical cord Wharton’s jelly, expanded in culture and characterized according to the recomendations from the International Society for Cell Therapy. Following this, an optimal protocol for the endothelial diffrentiation of UC-MSC was established. The endothelial-directed differentiation was based on the inhibition of the Transforming growth factor beta (TGF-β) signaling, specifficaly its receptor activin-like kinase 5 (ALK5). Based on the results gained, it was concluded that UC-MSC have a high ability to selfrenew and high diferentiation capacity, as well as that these cells can be differentiated into endothelial cells by inhibiting ALK5 recepto

Simulation Modelling of Permitted Left-Turn Saturation Flow Rate Based on Opposing Through-Flow Degree of Saturation

This paper presents the modelling of the saturation flow rate of the permitted left-turn in an exclusive lane. In the proposed model, the total permitted left-turn saturation flow rate is determined as a sum of saturation flow rates during the effective green time and the intergreen period. Primarily, the permitted left-turn saturation flow rate during the effective green time is modelled based on the opposing through-flow degree of saturation and the number of opposing through-flow lanes. The relation between the permitted left-turn saturation flow during the effective green time and these variables was examined using data from the simulation experiments in VISSIM. To our knowledge, this is the first study of the permitted left-turn saturation flow modelling based on the opposing through-flow degree of saturation instead of the opposing through-flow rate and signal-timing parameters. The proposed model was validated based on data collected at seven intersections with a permitted left-turn served in an exclusive lane. The permitted left-turn saturation flow rate could be accurately determined based on the opposing through-flow degree of saturation and the number of opposing lanes according to the RMSE of 58.4 pcu/h

CONTROL OF MHD MICROPOLAR FLUID FLOW

In this paper, the steady flow and heat transfer of an incompressible electrically conducting micropolar fluid through a parallel plate channel is investigated. The upper and lower plate have been kept at the two constant different temperatures and the plates are electrically insulated. The applied magnetic field is perpendicular to the flow, while the Reynolds number is significantly lower than one i.e. the considered problem is in induction-less approximation. The general equations that describe the discussed problem under the adopted assumptions are reduced to ordinary differential equations and closed-form solutions are obtained. The influences of each of the governing parameters on velocity, heat transfer on the plates (Nusselt number), flow rate and skin friction are discussed with the aid of graphs

TGF-β and MMPs: A complex regulatory loop involved in tumor progression

Transforming growth factor-β (TGF-β) has a dual and contradictory role in cancer. It is a tumor suppressor at early stages of tumor formation by virtue of its growth inhibitory and pro-apoptotic functions. However, at later stages of tumor progression, tumor cells lose their sensitivity to be growth inhibited by this cytokine, and, then, TGF-β facilitates tumor invasion and metastasis by diverse mechanisms, including the induction of an epithelial-mesenchymal transition, the suppression of the immune system and the stimulation of angiogenesis. Matrix metalloproteinases (MMPs) have also been shown to play a pivotal function in tumor cell migration, invasion and angiogenesis. MMPs and TGF-β form an interplay loop that may attenuate or promote tumor progression. On one hand, latent TGF-β, an inactive TGF-β precursor that is sequestered by the extracellular matrix, is proteolytically activated by MMPs; the released active cytokine may, then, suppress or promote tumor cell growth and invasiveness depending on the tumor stage. On the other hand, TGF-β regulates the expression of MMPs and their tissue inhibitors TIMPs in both tumor and stromal cells. MMPs in the tumor microenvironment are involved in the control of tumor cell growth and survival by modulating the bioavailability of growth factors and chemokines, and they also influence inflammation and angiogenesis. Thus, by modulating the net balance of MMPs and TIMPs in both compartments: the tumor and stroma, TGF-β regulates malignant progression.The work developed in our laboratories is supported by grants of the Spanish Ministry of Science and Innovation (grant SAF2010-19152 to MQ) and the Ministry of Science and Technological Development of the Republic of Serbia (grant 175062 to JFS and JK). GC is the recipient of a contract from the Juan de la Cierva program of the Spanish Ministry of Science and Innovation.Peer Reviewe

Malondialdehid kao nezavisan prediktor indeksa telesne mase kod adolescentkinja

Background: Given the fact that the studies that examined oxidative stress in relation to obesity that included late adolescents are scarce and show inconclusive results we aimed to investigate a wide spectrum of nitro-oxidative stress biomarkers i.e., malondialdehyde (MDA), xanthine oxidase (XO), xanthine oxidoreductase (XOD), xanthine dehydrogenase (XDH), advanced oxidation protein products (AOPP) and nitric oxide products (NOx), as well as an antioxidative enzyme, i.e., catalase (CAT) in relation with obesity in the cohort of adolescent girls ages between 16 and 19 years old. Methods: A total of 59 teenage girls were included in this cross-sectional study. Binary logistic regression analysis was performed to examine possible associations between bio- chemical and nitro-oxidative stress markers and body mass index (BMI). Results: There were not significant differences between oxidative stress markers between normal weight and overweight/obese girls (i.e., AOPP, XOD, XO, XDH) and CAT, except for MDA (p<0.001) and NOx (p=0.010) concentrations which were significantly higher in overweight/obese adolescent girls. Positive associations were evident between BMI and high sensitivity C-reactive protein (hsCRP) (OR=2.495), BMI and uric acid (OR=1.024) and BMI and MDA (OR=1.062). Multivariable binary regression analysis demonstrated sig- nificant independent associations of BMI and hsCRP (OR=2.150) and BMI and MDA (OR=1.105). Even 76.3% of the variation in BMI could be explained with this Model. Conclusions: Inflammation (as measured with hsCRP) and oxidative stress (as determined with MDA) independently correlated with BMI in teenage girls.Uvod: Imajući u vidu činjenicu da je malo studija koje su ispitivale povezanost oksidativnog stresa i gojaznosti kod adolescenata i da iste pokazuju oprečne rezultate, cilj istraživanja je bio da se ispita povezanost širokog spektra biomarkera nitro-oksidativnog stresa tj. malondialdehida (MDA), ksantin oksidaze (XO), ksantin oksidoreduktaze (XOD), ksantin dehidrogenaze (XDH), produkata uznapredovale oksidacije proteina (AOPP) i produkata azot-monoksida (NOx), kao i enzima antioksidativne zaštite, tj. katalaze (CAT) i gojaznosti u kohorti adolescentkinja starosne dobi izme|u 16 i 19 godina. Metode: Ukupno 59 tinejdžerki je uključeno u ovu studiju preseka. Binarna logistička regresija je primenjena u cilju ispitivanja potencijalne povezanosti između biohemijskih markera i markera nitro-oksidativnog stresa i indeksa telesne mase (ITM). Rezultati: Nije uočena razlika u biomarkerima oksidativnog stresa između normalno uhranjenih i predgojaznih/gojaznih adolescentkinja (odnosno AOPP, XOD, XO, XDH) i CAT, osim u vrednostima MDA (p<0,001) i NOx (p=0,010) koje su bile značajno veće kod predgojaznih/gojaznih adolescentkinja. Pozitivna korelacija je utvrđena izme|u ITM-a i visokosenzitivnog C-reaktivnog proteina (hsCRP) (OR=2,495), ITM-a i mokraćne kiseline (OR=1,024) i ITM-a i MDA (OR=1,062). Multivarijanta binarna regresija je pokazala nezavisnu povezanost ITM-a i hsCRP (OR=2,150), kao i ITM-a i MDA (OR=1,105). Čak 76,3% varijabiliteta ITM-a može biti objašnjeno ovim modelom. Zaključak: Inflamacija (merena hsCRP-om) i oksidativni stres (meren malondialdehidom) nezavisno koreliraju sa ITM kod adolescentkinja

Residual monomer content determination in some acrylic denture base materials and possibilities of its reduction

Background/Aim. Polymethyl methacrylate is used for producing a denture basis. It is a material made by the polymerization process of methyl methacrylate. Despite of the polymerization type, there is a certain amount of free methyl methacrylate (residual monomer) incorporated in the denture, which can cause irritation of the oral mucosa. The aim of this study was to determine the amount of residual monomer in four different denture base acrylic resins by liquid chromatography and the possibility of its reduction. Methods. After the polymerization, a postpolymerization treatment was performed in three different ways: in boiling water for thirty minutes, with 500 W microwaves for three minutes and in steam bath at 22º C for one to thirty days. Results. The obtained results showed that the amount of residual monomer is significantly higher in cold polymerizing acrylates (9.1-11%). The amount of residual monomer after hot polymerization was in the tolerance range (0.59- 0.86%). Conclusion. The obtained results denote a low content of residual monomer in the samples which have undergone postpolymerization treatment. A lower percent of residual monomer is established in samples undergone a hot polymerization

Application of Minkowski layer for microalloyed alumo-silicate ceramics grains fractal analysis

Porous aluminium-silicate ceramics, modified by alloying with magnesium and microalloying with alluminium belongs to a group of advanced multifunctional ceramics materials. This multiphase solid-solid system has predominantly amorphous microstructure and micro morphology. Intergranular and interphase areas are very complex, because they represent areas, where numbered processes and interactions take place, making new boundaries and regions with fractal nature. Solid contact between grains is actually very complex configuration of microcontacts with fractal nature. Fractal analysis of intergranular microstructure has included application of Minkowski layer. This layer is in correlation with fractal dimension, and defines grains contact probability. It represents convex layer of grains contour roughness and irregularity. Considering the fractal nature of intergranular contacts, it is possible to establish correlation between material electrical properties and fractal analysis, as a tool for future correlation with microstructure characterization