Ispitivanje biokompatibilnosti dentalnih materijala za punjenje kanala korena implantiranih u mišićno tkivo pacova

The purpose of this study was to investigate the biocompatibility of different dental materials for teeth root canal obturation, implanted in rat muscular tissue, by analyzing the type of muscular tissue inflammatory reaction level. In the preparation of Wistar rats M. biceps femoris, three different materials for root canal obturation were implanted: Sealapex (Kerr, Romulus, USA), AH-26 (DE Trey, Zurich, Switzerland) and Spongio cement material based on polymethil metacrylate - PMMA (Tomić, 1981, US patent 4296209). The used control material was sterile wax. The rats were sacrificed 30 and 60 days after implantation and the response of the tissue on implanted material was evaluated with standard histological methods on 6 _m sections stained with hematoxilin and eosin. Implantation of Sealapex in rat muscle tissue produced a strong acute inflammation, infiltration with massive polymorphonuclear and numerous giant cells. Acute inflammation still persisted 60 days after implantation. AH-26 produced a strong reaction around the alien body with predominantly limphocitic infiltration. Giant cells and macrophages contained phagocited pieces of material. After 60 days expressive chronic myositis was present with a mass of giant cells and proliferation of connective tissue. Thirty days later the results of histological investigations suggested that implanted PMMA based material still produced a connective fibrous capsula made of fibroblasts and fibrocytes around the implanted material. In the muscular tissue myositis developed forming granulomatous tissue. After 60 days a capsula was made of mature hyalinisated connective tissue without signs of inflammation in the surrounding muscular tissue. The reaction is similar to the reaction to inert control material, such as sterile wax. These findings suggest biocompatibility of PMMA based material for canal obturation.Cilj ovog rada je bio da se, na osnovu analize tipa i stepena inflamatorne reakcije koje izazivaju različiti materijali za punjenje kanala korena zuba - sileri, ispita njihova biokompatibilnost nakon unošenja u mišićno tkivo pacova. U poprečno presečen m. biceps femoris laboratorijskih pacova Wistar soja inplantirane su paste za opturaciju kanala Sealapex (Kerr, Romulus, USA), AH - 26 (DE Trey, Zurich, Switzerland) i Spongio cement preparat na bazi PMMA (Tomić, 1981, US patent 4296209), a kao kontrolni materijal stomatološki roze vosak. Životinje su bile žrtvovane nakon 30 i 60 dana, a materijal je pripreman za patohistološ ke pretrage standardnom tehnikom i bojen hematoksilin eozinom. Spongio cement u mišićnom tkivu oko implantiranog materijala daje hronič no zapaljenje, uz stvaranje vezivne kapsule sagrađene od fibroblasta i fibrocita. Nakon 60 dana, kapsula je sagrađena od zrelih ćelija i hijeliniziranih kolagenih vlakana. Implantacija Sealapexa u mišićno tkivo pacova, produkuje jaku hroničnu inflamaciju sa masivnom infiltracijom polimorfonukleara i džinovskih ćelija, koja postoji i nakon 60 dana od implantacije. Pasta AH-26 izaziva burnu reakciju mišićnog tkiva na strano telo sa izraženom limfocitarnom infiltracijom. Nakon 60 dana, prisutna je hronična inflamacija uz prisustvo brojnih džinovskih ćelija i makrofaga koje sadrže fagocitovane deliće materijala, dok vezivno tkivo proliferiše uz stvaranje cističnih tvorevina

The Montenegrin capital market: Calendar anomalies

Many researchers have shown that capital markets in CEE countries are weakly efficient in terms of calendar anomalies. The goal of this paper is to investigate whether the capital market in Montenegro is efficient regarding some of these anomalies. The main characteristics of the Montenegrin capital market are briefly explained. The empirical analysis is done on the daily values data of stock market index NEX20. An investigation of the January effect is implemented with the graphical representation of the rate of return for all the months of the seven-year period and by estimation of a regression model of return on index NEX20. The intercept represents the value of the return in January and it is insignificant. The holiday effect, tested by graphical representation for the Statehood Day data, was not present in the whole period. To investigate the turn-of-the-month effect we employed the graphical representation and regression model of the return rate on index NEX20 for the last week of every month and for the rest of the month. The value of the intercept, representing return for the last week of the month, is significant. The absence of some tested calendar anomalies suggests that the Montenegrin capital market is becoming more efficient

Algal Diversity Along the Serbian Stretch of the Sava River

Phytoplankton analysis is an essential part in water quality monitoring and predicting changes in aquatic ecosystems. In this study we investigated structure and diversity of algal communities along the Serbian stretch of the Sava River. We detected 109 species in four sampling localities (Bosut, Sremska Mitrovica, Jarak and Makiš). Species richness increases from Bosut to Jarak. However, a sudden decrease of species richness was recorded in the Makiš locality, probably due to increased pollution. Divisive numerical classification separates species with relatively narrow distribution (that are grouped in three clusters) from more common species (that form four clusters). Correspondence analysis clearly separates upper-stream sites (Bosut and Sremska Mitrovica) from down-stream sites Jarak and Makiš.Water Research and Management (2016), 6(2): 27-3

Reakcija potkožnog vezivnog tkiva na materijale za definitivno punjenje kanala korena

The aim of the study was to evaluate tissue response of two root canal sealers: Endomethasone (cink oxide eugenol-based sealers) and Ketac Endo Aplicap (glass ionomer based sealers). The sealers were freshly mixed and injected into subcutaneous connective tissue of the dorsal surface of experimental animals (Wistar Furth rats). The inflammatory reaction caused by the sealers was evaluated 7, 30 and 60 days after implantation using descriptive hisopathological analysis. The tissue sections were taken from injection sites. Each incision included skin,subcutaneous connective tissue and underlying muscular tissue. All blocks were proceeded using standard histological procedures. The tissue reactions were graded as mild,moderate or severe inflammation. After the seven days both sealers showed a moderate reaction with a decreasing trend. Both materials caused mild inflammation which diminished at the end of the experimental period. The results of this study demonstrate that Ketac Endo and Endomethasone is well tolerated by subcutaneus connective tissue of experimental animals.Cilj ovih proučavanja je bio ispitivanje biokompatibilnosti dva materijala za definitivno kanalno punjenje: Endomethasone (materijal na bazi cink oksid eugenola) i Ketac Endo Aplocap (glas jonomer cementa za kanalno punjenje). Sveže pripremljeni materijali su injicirani u potkožno vezivno tkivo leđnog dela eksperimentalnih životinja (pacovi Wistar soja). Intenzitet inflamatorne reakcije proveravan je nakon 7, 30 i 60 dana na osnovu patohistološke analize. Isečak je uzet sa mesta aplikacije materijala i obuhvatao je deo kože, potkožno tkivo i deo mišićnog sloja. Tkiva su podvrgnuta standardnoj histološkoj obradi. Reakcija tkiva na ubačeni materijal označena je kao blaga, srednja i jako izražena inflamacija. Posle prvog perioda od 7 dana oba materijala su izazvala intenzivnu zapaljensku reakciju tkiva sa kasnijom tendencom smanjenja inflamacije. Oba materijala su izazvala umereno zapaljenje koje je nestalo do kraja eksperimentalnog perioda. Postignuti rezultati ukazuju da su Ketac Endo i Endomethasone biokompatibilni u potkožnom vezivnom tkivu eksperimentalnih životinja

Influence of Gamma Radiation on Gas-Filled Surge Arresters

Current knowledge on the impact of γ radiation on gas-filled surge arresters (GFSA) is presented. Miniaturization of electronic components has led to their increased vulnerability to overvoltage. The combination of ionizing radiation and voltage surges is present in both space exploration and military applications. Some of the commonly used overvoltage protection components (transient suppressor diodes and metal-oxide varistors) perform poorly under ionizing radiation. GFSA demonstrate improved performance under γ irradiation. Performance of GFSA was tested under neutron + γ radiation, considering the effects of induced radiation. The effects of γ radiation were tested on commercially available GFSA components and on the purpose-built GFSA model. The model was used to measure the prebreakdown current and breakdown voltage of different electrode materials (aluminum, steel, brass) under varying gas pressures, under DC and pulse currents. The improvement of the performance of GFSA due to external γ radiation, combined with other improvements in the design (hollow cathode), can enable the use of GFSA without internal radiation sources in environments where γ radiation is present

Mogućnosti primene 'Spongio cementa' kao materijala za opturaciju kanala korena

The aim of this study was to evaluate of apical and canal opturation quality of polymethyl metacrylate based material for canal opturation. Investigations were included 60 extracted human single root teeth. Root canals were opturated by standard endodontic technic with three different materials. Teeth were decalcificated and enlightened in 2% methyl salicilate solution. Linear dye penetration was measured with bynocular magnifying glass with 25x magnification. Results showed that the highest apical dye penetration in canals opturated with PMMA based material in relation of AH-26 and Sealapex. Middle value of linear dye penetration in canals opturated with PMMA based material where smear layer was removed was significantly les then in group of teeth where smear layer present.Cilj ovog rada bio je da se ispita kvalitet apeksnog i kanalnog zaptivanja materijala za opturaciju kanala korena zuba na bazi polimetilmetakrilata (PMMA). U istraživanjima je korišćeno 60 ekstrahovanih jednokorenih zuba. Kanali su punjeni standardnom endodontskom tehnikom,primenom 3 različita materijala. Zubi su potom dekalcifikovani i prosvetljeni u 2% rastvoru metil salicilata. Linearna propustljivost boje merena je binokulamom lupom sa uvećanjem od 25 puta. Rezultati su pokazali najveću apikalnu propustljivost u kanala punjenih materijalom na bazi PMMA (1,06 i 1,31 mm) upoređenju sa AH-26 (0,70mm) i Sealapexom (0,69mm). Linearni prodor boje kod kanala punjenih sa PMMA i sa prethodno uklonjenim razmaznim slojem bio je značajno manji (l,06mm), nego u kanala gde razmazni sloj nije uklonjen (1,3Imm)

Tourism price normalities in two Adriatic east coast ’euro’ countries

This debut work offers a stunning look at real vs nominal prices that consider more than just inflation. The inadequate examination of hospitality price comparison is investigated between two non-neighbouring Adriatic east coast countries – Slovenia and Montenegro – using the euro. Hospitality prices are an essential indicator in hospitality markets, destination marketing and management planning. Using 73 monthly time-series data for the economic crisis period from December 2008 to December 2014, this period covers one shock in a series. One of the key managerial features of cointegrated spatial hospitality price spread was that Montenegro followed Slovenian hospitality prices. Hospitality prices in Montenegro and Slovenia tend to be weakly integrated into the long term and seasonally driven in the short term. In addition, the econometric experimentation has given a theoretical novelty for underpinned and undermined tourism economy modelling in normalities. This state-of-the-art econometric feature is included in a customary vector error correction model (VECM). Robust applied results recognise that hospitality prices in Montenegro are domestic driven and in Slovenia Eurozone driven. This finding is relevant for applied economics on obtaining a normally distributed price model. Its theoretical and managerial implications are vital for hospitality economics, marketing and tourism management

Uticaj različitih 3D biomaterijala na osteoblastnu diferencijaciju mezenhimalnih ćelija zubne pulpe

Millions of patients worldwide suffer from bone disease or bone defects such as osteosarcoma, osteoporosis and bone fractures. In order to solve the problem of lost bone tissue, bone tissue engineering major emphasis is on tissue regeneration rather than tissue replacement, which is why it became the subject of growing interest. Stem cells and scaffolds have an essential role in the production of new tissue by tissue engineering. Cellular component is necessary for the generation and establishment of the extracellular matrix in new tissue, while scaffold is responsible for providing mechanical stability and the foundation of a new three-dimensional tissue organization. The main objective of the dissertation was to examine the differential capacity of isolated dental pulp mesenchymal cells in relation to 4 different cell carriers - scaffolds: porous hydroxyapatite (pHAP) and porous hydroxyapatite combined with 3 polymers: poly lactic-co-glycolic acid (PLGA), alginate and ethylene vinyl acetate / ethylene vinyl versatate (EVA / EVV). The research involved the isolation of dental pulp mesenchymal cells from human exfoliated deciduous teeth shift by "outgrowth" method and their characterization by flow cytometry. Characterization of synthesized biomaterials was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and methods of the specific surface area of hydroxyapatite powder (BET method). Cytotoxicity of biomaterials in the presence of mesenchymal cells was tested by an indirect method using the MTT test and by a direct method using the LDH test. Evaluation of osteogenic differentiation of isolated mesenchymal cells on 3D biomaterials samples was performed by alizarin red staining, alkaline phosphatase activity measurements and scanning electron microscopy. The differentiation of isolated dental pulp cells in 3 different cell types - adipocytes, chondrocytes and osteoblasts, and characterization of these cells by CD29, CD73, CD90 and CD34 antibodies, showed the isolated cells were mesenchymal stem cells...Milioni pacijenata širom sveta pate od oboljenja kostiju ili koštanih defekata kao što su osteosarkom, osteoporoza i frakture kostiju. U cilju rešavanja problema izgubljenog koštanog tkiva, inženjerstvo koštanog tkiva glavni akcenat stavlja na tkivnu regeneraciju a ne na zamenu tkiva, zbog čega postaje predmet sve većeg interesovanja. Matične ćelije i skafoldi imaju esencijalnu ulogu u stvaranju novog tkiva putem tkivnog inženjerstva. Ćelijska komponenta je neophodna zbog stvaranja i uspostavljanja ekstracelularnog matriksa u novom tkivu, dok su skafoldi zaduženi za obezbeđivanje mehaničke stabilnosti i temelja trodimenzionalne organizacije novog tkiva. Osnovni cilj doktorske disertacije bio je ispitati diferencijalni kapacitet izolovanih mezenhimalnih ćelija zubne pulpe u odnosu na 4 različita ćelijska nosača – skafolda: poroznog hidroksiapatita (pHAP) i poroznog hidroksiapatita u kombinaciji sa 3 polimera: polilaktid-koglikolnom kiselina (PLGA), alginatom i polimerom etilen vinil acetat/versatatom (EVA/EVV). Istraživanje je podrazumevalo izolovanje mezenhimalnih ćelija zubne pulpe poreklom iz mlečnih zuba u fiziološkoj smeni “outgrowth” metodom i njihovu karakterizaciju metodom protočne citometrije. Sintetisani biomaterijali su okarakterisani uz pomoć Fourier transform infracrvene spektroskopije (FTIR), rentgen difrakcije (XRD), mikroskopije atomskih sila (AFM), skening elektronske mikroskopije (SEM) i metode analize specifične površine čestice praha hidroksiapatita (BET metoda). Citotksičnost biomaterijala u prisustvu mezenhimalnih ćelija je ispitivana indirektnom metodom pomoću MTT testa i direktnom metodom pomoću LDH testa. Osteogena diferencijacija izolovanih mezenhimalnih ćelija u prisustvu različitih 3D biomaterijala praćena je bojenjem uzoraka alizarin crvenim, merenjem aktivnosti alkalne fosfataze i skening elektronskom mikroskopijom. Diferencijacijom ćelija u 3 različite vrste ćelija – adipocite, hondrocite i osteoblaste, i karakterizacijom CD29, CD73, CD90 i CD34 antitelima, pokazano je da su izolovane ćelije iz zubne pulpe mezenhimalne matične ćelije. Takođe, rezultati istraživanja pokazuju da su ispitivani skafoldi bili adekvatno dizajnirani i da su imali odgovarajuću morfologiju površine koja je neophodna za ćelijske nosače..