Uticaj različitih modifikacija površine titana fizičkim i hemijskim metodama na njegovu citokompatibilnost i imunomodulacijska svojstva

Introduction: Titanium and its alloys are being used as dental implant materials due to its biocompatibility and solid physical and mechanical properties. Corrosion properties of titanium and its alloys in acid and alkaline solutions and biological fluids are not satisfying and can be surpassed by modifying its surface area. Biofunctionality of the modified surface depends on the techniques being used. There are many methods to modify titanium surface such as chemical methods that, together with subsequent thermal treatment, provide the formation of a titanium oxide layer, or physical methods, such as deposition of a hydroxyapatite coatings (HAP). Dental implants can increase production of cytokines and chemokines with proinflammatory properties. Aim: Investigation of the effect of the titanium alloy (Ti6Al4V) surface modification by chemical treatment and subsequent thermal treatment, and deposition of a hydroxyapatite coating, on biocompatibility, assesed by cytotoxicity evaluation in vitro, and on the immunomodulatory action of titanium in vitro. Material and methods: Cytotoxicity was determined by using in vitro test of direct contact of titanium alloy samples with L929 cells or indirectly, by determining metabolic activity of L929 cells in the presence of different solutions of conditioned medium (KM). Mouse fibroblast (L929) cell line was used. Metabolic activity was determined with MTT test, cell proliferation was measured with 3[H+]-thymidine test, while reactive oxygen species (ROS) production was determined by flow cytometry after labeling with dichloro-dihydro-fluorescein diacetate (DCFH-DA). Necrosis and apoptosis were measured with propidium iodide (PI) cell staining, measuring lactate dehydrogenase (LDH) production, and by analyzing gene expression of mice caspases 3, 8 and 9 with Real Time PCR method. Cell growth and morphological analysis of L929 cells were determined with phase contrast light microscopy, while viability was determined with Trypan Blue. Immunomodulating effect of the modified titanium surfaces was measured on phytohemaglutinin (PHA) model of peripheral blood mononuclear cells (PBMNC)...Titan i njegove legure se upotrebljavaju kao materijali za dentalne implantate zbog pokazane biokompatibilnosti titana i dobrih fizičkih i mehaničkih svojstva. Korozivna svojstva titana i njegovih legura u kiselim i baznim rastvorima, i u biološkim fluidima nisu zadovoljavajuća što je moguće prevazići modifikacijom njihove površine. Biofunkcionalnost modifikovanih površina titana zavisi od tehnika kojima se sprovode modifikacije. Postoje brojne metode modifikacije površine titana, kao hemijske metode koje zajedno sa naknadnim termičkim tretmanom obezbeđuju formiranje titan-oksidnog sloja ili fizičke metode nanošenja prevlaka hidroksiapatita (HAP). Dentalni implantati mogu dovesti do povećane produkcije citokina i hemokina sa proinflamacijskim delovanjem. Cilj istraživanja: Ispitivanje efekta modifikacije površine titanove legure (Ti6Al4V) hemijskom obradom i naknadnim termalnim tretmanom, i nanošenjem prevlake hidroksiapatita, na biokompatibilnost merenu pomoću određivanja citotoksičnosti in vitro, kao i na imunomodulacijsko delovanje titana in vitro. Materijal i metode: Citotoksičnost je ispitivana in vitro, primenom testova direktnog kontakta uzoraka titanovih legura sa L929 ćelijama ili indirektno, ispitivanjem metaboličke aktivnosti L929 ćelija u prisustvu različitih razblaženja kondicioniranog medijuma (KM). Korišćena je ćelijska linija mišijih fibroblasta (L929). Metabolička aktivnost je merena MTT testom, ćelijska proliferacija je merena testom ugradnje 3[H+]-timidina, dok je produkcija slobodnih radikala kiseonika (ROS) određivana protočnom citofluorimetrijom nakon obeležavanja sa dihloro-dihidro-fluorescin diacetatom (DCFH-DA). Nekroza i apoptoza su merene bojenjem ćelija sa propidijum jodidom, merenjem produkcije laktatdehidrogenaze (LDH), kao i analizom ekspresije gena za mišje kaspaze 3, 8 i 9 metodom lančane reakcije polimeraze u realnom vremenu (Real-Time PCR). Ćelijski rast i morfološka analiza L929 ćelija je procenjivana fazno kontrasno svetlosnom mikroskopijom, dok je vijabilnost određivana pomoću tripan plavog. Imunomodulacijski efekat modifikovanih površina titana je ispitivan na modelu fitohemaglutininom (PHA) aktiviranih humanih mononuklearnih ćelija periferne krvi (PBMNC)..

Influence of different physical and chemical modifications of titanium surface on its citocompatibility and immunomodulatory properties

Titan i njegove legure se upotrebljavaju kao materijali za dentalne implantate zbog pokazane biokompatibilnosti titana i dobrih fizičkih i mehaničkih svojstva. Korozivna svojstva titana i njegovih legura u kiselim i baznim rastvorima, i u biološkim fluidima nisu zadovoljavajuća što je moguće prevazići modifikacijom njihove površine. Biofunkcionalnost modifikovanih površina titana zavisi od tehnika kojima se sprovode modifikacije. Postoje brojne metode modifikacije površine titana, kao hemijske metode koje zajedno sa naknadnim termičkim tretmanom obezbeđuju formiranje titan-oksidnog sloja ili fizičke metode nanošenja prevlaka hidroksiapatita (HAP). Dentalni implantati mogu dovesti do povećane produkcije citokina i hemokina sa proinflamacijskim delovanjem. Cilj istraživanja: Ispitivanje efekta modifikacije površine titanove legure (Ti6Al4V) hemijskom obradom i naknadnim termalnim tretmanom, i nanošenjem prevlake hidroksiapatita, na biokompatibilnost merenu pomoću određivanja citotoksičnosti in vitro, kao i na imunomodulacijsko delovanje titana in vitro. Materijal i metode: Citotoksičnost je ispitivana in vitro, primenom testova direktnog kontakta uzoraka titanovih legura sa L929 ćelijama ili indirektno, ispitivanjem metaboličke aktivnosti L929 ćelija u prisustvu različitih razblaženja kondicioniranog medijuma (KM). Korišćena je ćelijska linija mišijih fibroblasta (L929). Metabolička aktivnost je merena MTT testom, ćelijska proliferacija je merena testom ugradnje 3[H+]-timidina, dok je produkcija slobodnih radikala kiseonika (ROS) određivana protočnom citofluorimetrijom nakon obeležavanja sa dihloro-dihidro-fluorescin diacetatom (DCFH-DA). Nekroza i apoptoza su merene bojenjem ćelija sa propidijum jodidom, merenjem produkcije laktatdehidrogenaze (LDH), kao i analizom ekspresije gena za mišje kaspaze 3, 8 i 9 metodom lančane reakcije polimeraze u realnom vremenu (Real-Time PCR). Ćelijski rast i morfološka analiza L929 ćelija je procenjivana fazno kontrasno svetlosnom mikroskopijom, dok je vijabilnost određivana pomoću tripan plavog. Imunomodulacijski efekat modifikovanih površina titana je ispitivan na modelu fitohemaglutininom (PHA) aktiviranih humanih mononuklearnih ćelija periferne krvi (PBMNC)...Introduction: Titanium and its alloys are being used as dental implant materials due to its biocompatibility and solid physical and mechanical properties. Corrosion properties of titanium and its alloys in acid and alkaline solutions and biological fluids are not satisfying and can be surpassed by modifying its surface area. Biofunctionality of the modified surface depends on the techniques being used. There are many methods to modify titanium surface such as chemical methods that, together with subsequent thermal treatment, provide the formation of a titanium oxide layer, or physical methods, such as deposition of a hydroxyapatite coatings (HAP). Dental implants can increase production of cytokines and chemokines with proinflammatory properties. Aim: Investigation of the effect of the titanium alloy (Ti6Al4V) surface modification by chemical treatment and subsequent thermal treatment, and deposition of a hydroxyapatite coating, on biocompatibility, assesed by cytotoxicity evaluation in vitro, and on the immunomodulatory action of titanium in vitro. Material and methods: Cytotoxicity was determined by using in vitro test of direct contact of titanium alloy samples with L929 cells or indirectly, by determining metabolic activity of L929 cells in the presence of different solutions of conditioned medium (KM). Mouse fibroblast (L929) cell line was used. Metabolic activity was determined with MTT test, cell proliferation was measured with 3[H+]-thymidine test, while reactive oxygen species (ROS) production was determined by flow cytometry after labeling with dichloro-dihydro-fluorescein diacetate (DCFH-DA). Necrosis and apoptosis were measured with propidium iodide (PI) cell staining, measuring lactate dehydrogenase (LDH) production, and by analyzing gene expression of mice caspases 3, 8 and 9 with Real Time PCR method. Cell growth and morphological analysis of L929 cells were determined with phase contrast light microscopy, while viability was determined with Trypan Blue. Immunomodulating effect of the modified titanium surfaces was measured on phytohemaglutinin (PHA) model of peripheral blood mononuclear cells (PBMNC)..

Poređenje resorptivnih membrana u vođenoj koštanoj regeneraciji humanog i bovinog porekla

The properties of membranes for guided bone regeneration have been described by a number of authors. These involve biocompatibility, appropriate barrier features (mechanical prevention of soft tissue proliferation), tissue integration, immunologic neutrality, preservation of the space for new alveolar bone, and simplicity of application. Such membrane must hold out against the masticatory forces and tissue tension of the flap, and prevent the collapse of soft tissues and wound space reduction. The property of integration into the tissue guarantees wound stabilization and inhibits epithelial migration. The aim of this study was to compare and evaluate the influence of human resorbable demineralized membrane (RHDM) and bovine resorbable demineralized membrane (RBDM) on bone regeneration. The experiment, approved by the Ethical Committee, was performed on six dogs and conducted into three phases. Bone defects were created in all six dogs on the left side of the mandible, 8 weeks after extraction of the second, third and fourth premolar. One defect was covered with 200 μm thick RHDM, one with 200 μm thick RBDM, and the third defect was left empty (control defect). The pathohistological analysis was done two, four and six months after the surgery. In the third phase samples of bone tissue were taken and subjected to patohistological analysis. In all six dogs the defects treated with RHDM 200μm thick showed a higher level of bone regeneration in comparison with the defect treated with RBDM 200 μm thick and especially with the control defect. Our results demonstrated that the human membrane showed the least soft tissue ingrowth and promoted better bone formation at 6 months compared with a bovine one.Svojstva membrane za vođenu koštanu regeneraciju opisali su brojni autori. Ona uključuju biokompatibilnost, odgovarajuću barijernu moć (mehaničko sprečavanje proliferacije mekog tkiva), tkivnu integraciju, imunološku inertnost, očuvanje prostora za novu alveolarnu kost i jednostavnost primene. Membrana mora da izdrži sile žvakanja i tkivne tenzije režnja, da spreči kolaps mekih tkiva i smanjenje prostora rane. Svojstvo tkivne integracije omogućava stabilizaciju rane i inhibiciju epitelne migracije. Cilj studije je bio da ispita uticaj humane resorptivne demineralizovane membrane (RHDM) i bovine resorptivne demineralizovane membrane (RBDM) na koštanu regeneraciju i da ih međusobno uporedi. Eksperimentalna studija rađena na 6 pasa rase nemački ovčar, sprovedena je u tri faze. U prvoj fazi izvršena je ekstrakcija drugog, trećeg i četvrtog premolara sa leve strane. Osam nedelja nakon ekstrakcije, formirana su tri defekta na levoj strani mandibule i prekrivena humanom membranom debljine 200μm, bovinom membranom debljine 200 μm a treći defekt je ostavljen prazan (kontrolni defekt). Patohistološka analiza rađena je nakon dva, četiri i šest meseci posle hirurške intervencije. U trećoj fazi uzorci koštanog tkiva podvrgnuti su patohistološkoj analizi. Kod svih 6 pasa, defekti prekriveni humanom membranom debljine 200 μm, pokazali su patohistološkom analizom znatno veći stepen koštane regeneracije u poređenju sa defektima prekrivenim sa bovinom membranom i naročito sa kontrolnim defektom. Naši rezultati su pokazali da je humana membrana pokazala najmanje prorastanje mekim tkivom i bolju koštanu regeneraciju nakon 6 meseci u poređenju sa bovinom

THE ROLE AND IMPORTANCE OF CHROMATOGRAPHY AND SPECTROSCOPY IN THE ANALYSIS OF NONCONVENTIONAL FUELS

Nekonvencionalna goriva sve više dobivaju na značaju zbog ograničene raspoloživosti sirove nafte i naglog rasta automobilske industrije i transportnog sektora što je rezultiralo povećanjem emisija ispušnih plinova u okoliš. Ispušni plinovi koji nastaju izgaranjem fosilnih goriva korištenih u transportnom sektoru smanjuju kvalitetu zraka i time utječu direktno na ljudsko zdravlje. Biogoriva su ekološki prihvatljivija alternativna goriva koja se dobivaju iz sirovina životinjskog i biljnog porijekla. Sve se više razvijaju nove i učinkovitije analitičke metode s obzirom da poznavanje kemijskog sastava predstavlja izazov analitičarima. U ovome radu prikazane su najčešće i najznačajnije kromatografske i spektrometrijske metode u analizi sirovina i nekonvencionalnih goriva. U radu su prikazani karakteristični kromatogrami i spektri pojedinih sirovina za proizvodnju biogoriva i kromatogrami biodizela snimljeni u Laboratoriju za ispitivanje voda, ugljikovodika i materijala (Služba Centralni ispitni laboratorij) u INA Industrija nafte d.d.Nonconventional fuels are gaining in importance due to limited availability of crude oil and rapid growth of the automotive industry and transportation sector which is resulting in increased emissions into the environment. Exhaust gases associated with combustion of fossil fuels used in transportation sector reduce air quality and thus have direct impact on human health. Biofuels are more environmentally friendly alternative fuels that are produced from animal or vegetable feedstocks. Developments of new and more effective analytical methods are increasing since the knowledge of the chemical composition represents challenge to analysts. In this paper, the most common and important chromatographic and spectroscopic methods in the analysis of feedstocks and nonconventional fuels are shown. The paper also presents the characteristic chromatogram and spectra of certain feedstocks for biofuel production and chromatogram of biodiesel recorded in the Laboratory for testing, water, hydrocarbons and materials (Central Testing Laboratory Department) in INA Petroleum Industry

Procena efikasnosti fotodinamske terapije u terapiji periimplantitisa posle tri meseca - randomizirana kontrolisana klinička studija

Introduction Peri-implantitis is an inflammatory lesion of peri-implant tissues. Eradication of the causative bacteria and decontamination of the implant surface is essential in achieving predictable and stabile clinical results. Photodynamic therapy (PDT) is non-invasive adjuvant therapeutic method to surgery in the treatment of bacterial infection. Objective The aim of this study was to evaluate early clinical and microbiological outcomes of periimplantitis after surgical therapy with adjuvant PDT. Methods Fifty-two diagnosed peri-implantitis sites were divided into two groups. PDT was used for decontamination of implant surface in the study group; in the control group, chlorhexidine gel (CHX) followed by saline irrigation was applied. Several clinical parameters were recorded before the treatment (baseline values) and three months after surgical treatment. Samples for microbiological identification were collected before therapy, during the surgical therapy (before and after decontamination of implant surface), and three months thereafter, and analyzed with identification systems using biochemical analysis. Results The use of PDT resulted in significant decrease of bleeding on probing in comparison to CHX (p lt 0.001). It showed significant decontamination of implant surfaces with complete elimination of anaerobic bacteria immediately after surgical procedure and three months later. Conclusion The results indicate that PDT can be used as an adjuvant therapy to surgery for decontamination of implant surface and surrounding peri-implant tissues within the treatment of peri-implantitis.Uvod Periimplantitis je inflamatorni proces koji zahvata meka tkiva i potpornu kost oko oseointegrisanog implantata. Eliminacija patogenih mikroorganizama i dekontaminacija implantne površine predstavlju najbitniji korak u postizanju stabilnih kliničkih rezultata. Fotodinamska terapija (FDT) predstavlja dodatni neinvazivni metod u terapiji bakterijskih infekcija. Cilj rada Cilj rada bila je procena kliničkih i mikrobioloških parametara nakon hirurške terapije periimplantitisa uz dodatnu primenu FDT. Metode rada Sva dijagnostikovana mesta periimplantitisa (n = 52) bila su podeljena u dve grupe: u studijskoj grupi, za dekontaminaciju implantne površine tokom hirurške procedure korišćena je FDT; u kontrolnoj grupi, za dekontaminaciju implantne površine korišćen je hlorheksidin u gelu (CHX). Klinički parametri praćeni su pre terapijske procedure i tri meseca posle terapije. Uzorci za mikrobiološku analizu uzimani su pre i tri meseca posle terapije, kao i tokom hirurške procedure, pre i posle dekontaminacije implantne površine. Za identifikaciju izolovanih anaeroba korišćen je sistem koji radi po principu biohemijske analize izolovanih mikrobioloških sojeva. Rezultati studije su pokazali da primenom FDT dolazi do znatne redukcije krvarenja na provokaciju u poređenju sa primenom CHX (p lt 0,001). Primena FDT, kao pomoćnog terapijskog sredstva, omogućava potpunu eliminaciju anaerobnih bakterija sa implantne površine. Zaključak Rezultati pokazuju da FDT može da se koristi kao pomoćno terapijsko sredstvo za dekontaminaciju implantne površine i periimplantnog tkiva u okviru terapije periimplantitisa

Poređenje resorptivnih membrana u vođenoj koštanoj regeneraciji humanog i bovinog porekla

The properties of membranes for guided bone regeneration have been described by a number of authors. These involve biocompatibility, appropriate barrier features (mechanical prevention of soft tissue proliferation), tissue integration, immunologic neutrality, preservation of the space for new alveolar bone, and simplicity of application. Such membrane must hold out against the masticatory forces and tissue tension of the fl ap, and prevent the collapse of soft tissues and wound space reduction. The property of integration into the tissue guarantees wound stabilization and inhibits epithelial migration. The aim of this study was to compare and evaluate the infl uence of human resorbable demineralized membrane (RHDM) and bovine resorbable demineralized membrane (RBDM) on bone regeneration. The experiment, approved by the Ethical Committee, was performed on six dogs and conducted into three phases. Bone defects were created in all six dogs on the left side of the mandible, 8 weeks after extraction of the second, third and fourth premolar. One defect was covered with 200 μm thick RHDM, one with 200 μm thick RBDM, and the third defect was left empty (control defect). The pathohistological analysis was done two, four and six months after the surgery. In the third phase samples of bone tissue were taken and subjected to patohistological analysis. In all six dogs the defects treated with RHDM 200μm thick showed a higher level of bone regeneration in comparison with the defect treated with RBDM 200 μm thick and especially with the control defect. Our results demonstrated that the human membrane showed the least soft tissue ingrowth and promoted better bone formation at 6 months compared with a bovine one.Svojstva membrane za vođenu koštanu regeneraciju opisali su brojni autori. Ona uključuju biokompatibilnost, odgovarajuću barijernu moć (mehaničko sprečavanje proliferacije mekog tkiva), tkivnu integraciju, imunološku inertnost, očuvanje prostora za novu alveolarnu kost i jednostavnost primene. Membrana mora da izdrži sile žvakanja i tkivne tenzije režnja, da spreči kolaps mekih tkiva i smanjenje prostora rane. Svojstvo tkivne integracije omogućava stabilizaciju rane i inhibiciju epitelne migracije. Cilj studije je bio da ispita uticaj humane resorptivne demineralizovane membrane (RHDM) i bovine resorptivne demineralizovane membrane (RBDM) na koštanu regeneraciju i da ih međusobno uporedi. Eksperimentalna studija rađena na 6 pasa rase nemački ovčar, sprovedena je u tri faze. U prvoj fazi izvršena je ekstrakcija drugog, trećeg i četvrtog premolara sa leve strane. Osam nedelja nakon ekstrakcije, formirana su tri defekta na levoj strani mandibule i prekrivena humanom membranom debljine 200μm, bovinom membranom debljine 200 μm a treći defekt je ostavljen prazan (kontrolni defekt). Patohistološka analiza rađena je nakon dva, četiri i šest meseci posle hirurške intervencije. U trećoj fazi uzorci koštanog tkiva podvrgnuti su patohistološkoj analizi. Kod svih 6 pasa, defekti prekriveni humanom membranom debljine 200 μm, pokazali su patohistološkom analizom znatno veći stepen koštane regeneracije u poređenju sa defektima prekrivenim sa bovinom membranom i naročito sa kontrolnim defektom. Naši rezultati su pokazali da je humana membrana pokazala najmanje prorastanje mekim tkivom i bolju koštanu regeneraciju nakon 6 meseci u poređenju sa bovinom

Citotoksičnost legure titana obložene hidroksiapatitom pomoću mlaza plazme

Background/Aim. The deposition of hydroxyapatite (HAP) on the surface of titanium (Ti) alloys enhances bioactivity and osseointegration of the alloys which are widely used as implant materials in dentistry and orthopaedic surgery. However, the stability of HAP and subsequent biocompatibility of such alloys depends on the coating technique. The aim of this work was to test the cytotoxicity of a Ti alloy (Ti6Al4V), coated with HAP by a new plasma deposition method. Methods. The Ti6Al4V samples prepared as discs, 10 mm in diameter and 2 mm in thickness, were coated with HAP (one or both sides of the alloy) by an innovative atmospheric plasma jet method. The cytotoxicity of uncoated and HAP coated Ti6Al4V samples was evaluated by examining the morphological changes and viability of L929 fibroblasts in direct contact with the test materials. Adequate negative (polystyrene) and positive (nickel) control discs of the same size were used. The indirect cytotoxicity was determined by cultivating L929 cells with conditioning medium (CM), prepared as extract of the test samples incubated in the complete Roswell Park Memorial Institute (RPMI) 1640 medium for cell cultures. The cytotoxic effect was evaluated based on the degree of metabolic activity, necrosis, apoptosis and proliferation of L929 cells, using the appropriate assays. Results. Uncoated and one side HAP coated Ti6Al4V alloys were classified as non-cytotoxic according to the current ISO 10993-5 criteria, whereas two sides HAP coated Ti6Al4V alloy samples were slightlymoderate cytotoxic. The cytotoxicity manifested as the inhibition of metabolic activity and proliferation of L929 cells as well as the induction of their apoptosis and necrosis was significantly reduced by conditioning of HAP/Ti6Al4V alloys for 24 hours. The cytotoxic effect of HAP/Ti6Al4V CM only partly decreased in the presence of nifelate, a calcium (Ca) channel blocker, suggesting that Ca ions were not the only responsible cytotoxic agent. Conclusion. The original HAP coating procedure by atmospheric plasma spraying with high energy input enables the production of the stable adhesive coatings on Ti6Al4V alloys. Their cytotoxicity, which depends on the quantity of HAP coating layer, could be significantly reduced up to the non-cytotoxic level by prior conditioning of the alloys in culture medium. Such a procedure, which removes leachable toxic components, could be useful before implantation of HAP coated alloys in vivo. © 2019, Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved

Nanodesigned coatings obtained by plasma electrolytic oxidation of titanium implant and their cytotoxicity

The titanium implant was treated with plasma electrolytic oxidation and subsequent ionic exchange and thermal treatment in order to obtain bioactive layer consisting of titanium oxide, calcium and sodium titanates and hydroxyapatite, as confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed that the given method, besides corresponding phase composition, enables suitable nanotopology for cell attachment and proliferation. Cytotoxicity investigations by MTT, LDH and propidium iodide assays and light microscopy showed that these coatings were not toxic to L929 cells

Production process eps and quality control in the case of Lim Mont d.o.o. Vrbanovec

U ovom radu govori se o procesu izrade stiropora (EPS – ekspandirani polistiren) u tvrtki Lim-mont d.o.o. iz Vrbanovca. Objašnjene su definicije, način dobivanja i kratka povijest polistirena. Zatim ekspandiranje PS-a (polistirena), njegove tehničke karakteristike i svojstva vodljivosti te prednosti i nedostaci stiropora kao vrste materijala korištenog za toplinsku izolaciju. U praktičnom djelu rada opisan je postupak proizvodnje stiropora u tvrtki Lim-mont d.o.o. iz Vrbanovca. Proizvodnja stiropora se provodi u osam faza: 1. faza: Skladištenje sirovine za ekspandiranje, 2. faza: Ekspandiranje kuglica SIRCEL F900SR, 3. faza: Čuvanje stiropora u paropropusnim silosima, 4. faza: Ekspandiranje stiropora u blok formu, 5. faza: Skladištenje blok forme, 6. faza: Obrada blok forme, 7. faza: Provjera kvalitete i 8. faza: Skladištenje gotovog proizvoda. Detaljno je opisan postupak proizvodnje po stupnjevima, sa slikama iz proizvodnog procesa (materijal, strojevi,...) i pratećim listama za kontrolu proizvoda. Opisani su strojevi korišteni kod proizvodnje stiropora i sustav održavanja strojeva.This work discusses the process of making styrofoam (EPS) in the company Limmont d.o.o. from Vrbanovec. First are explains the definition, a way of getting and short history of polystyrene. Then expanding the PS, its technical characteristics and properties of conductivity, the advantages and disadvantages of Styrofoam as the type of material used for thermal isolation. In the practical part of the work is described a process of producing Styrofoam in company Lim-mont d.o.o. from Vrbanovec. Production of polystyrene is carried out in eight stages: Stage 1: Storage of raw materials for expansion, Stage 2: Expansion of balls Syrians F900SR, Stage 3: Protection of styrofoam in the vapor-permeable silos, Stage 4: Expansion of Styrofoam into a block form, Stage 5: Storage block form, Stage 6: Processing block form, Stage 7: Quality control and Stage 8: Storage of the finished product. The procedure of the production stages is described in detail, with pictures from the production process (material, machines,...) and the accompanying lists of controling the product in production process. At the end of the work there are described machines used in the production of Styrofoam and maintenance tools

Hedgehog signaling pathway and vitamin D receptor gene variants as potential risk factors in odontogenic cystic lesions

ObjectivesGenetic variants in the hedgehog signaling pathway and VDR gene are involved in inflammatory responses and neoplastic transformation. Current study investigated whether single-nucleotide polymorphisms in the hedgehog pathway genes PTCH1, GLI1, SMO, and VDR contribute to susceptibility to odontogenic cystic lesions, odontogenic keratocysts, or inflammatory radicular cysts.Material and methodsCurrent study examined polymorphisms of PTCH1 (rs357564) and PTCH1 insertion (IVS1-83), GLI1 (rs2228224, rs2228226), SMO (rs2228617), and VDR (rs2228570, rs731236, rs7975232). A case-control study was conducted on 41 keratocyst cases, 43 radicular cyst cases, and control group of 93 healthy individuals without cystic lesions, radiographically confirmed. Single-nucleotide polymorphisms were assessed by real-time and TaqMan SNP genotyping assays, while PTCH1 insertion 18bp IVS1-83 polymorphism was determined by PCR.ResultsThe difference in genotype distribution between keratocyst cases and control group was observed for PTCH1 IVS1-83 and GLI1 rs2228224 polymorphism (p=0.022, p=0.030, respectively). Homozygous mutant GG genotype within GLI1 rs2228224 is associated with increased susceptibility for odontogenous keratocysts, with adjusted odds ratio of 4.098 (confidence interval of 1.482-11.328, p=0.007).ConclusionGLI1 rs2228224 and PTCH1 polymorphisms could predispose to odontogenic keratocysts.Clinical relevanceVariants in hedgehog signaling pathway genes, such as GLI1 and PTCH1, and vitamin D receptor gene, might be considered as molecular risk factors in odontogenic cystic lesions and potential targets for novel therapeutic approaches