Uloga tiolne grupe u modifikaciji proteina sa metilglioksalom

Methylglyoxal is a highly reactive a-oxoaldehyde with elevated production in hyperglycemia. It reacts with nucleophilic Lys and Arg side-chains and N-terminal amino groups causing protein modification. In the present study, the importance of the reaction of the Cys thiol group with methylglyoxal in protein modification, the competitiveness of this reaction with those of amino and guanidine groups, the time course of these reactions and their role and contribution to protein cross-linking were investigated. Human and bovine serum albumins were used as model systems. It was found that despite the very low levels of thiol groups on the surface of the examined protein molecules (approx. 80 times lower than those of amino and guanidino groups), a very high percentage of it reacts (25-85%). The amount of reacted thiol groups and the rate of the reaction, the time for the reaction to reach equilibrium, the formation of a stable product and the contribution of thiol groups to protein cross-linking depend on the methylglyoxal concentration. The product formed in the reaction of thiol and an insufficient quantity of methylglyoxal (compared to the concentrations of the groups accessible for modification) participates to a significant extent (4%) to protein cross-linking. Metformin applied in equimolar concentration with methylglyoxal prevents its reaction with amino and guanidino groups but, however, not with thiol groups.Metilglioksal je veoma reaktivni α-oksoaldehid koji se povećano stvara u hiperglikemiji. Reaguje sa nukleofilnim grupama bočnih ostataka Lys, Arg i N-terminalnom amino-grupom, što dovodi do modifikacije proteina. U ovom radu ispitivani su značaj reakcije SH grupe sa metilglioksalom u modifikaciji proteina, konkurentnost ove reakcije u odnosu na reakcije sa amino- i gvanidino-grupom, tok ovih reakcija i njihova uloga i doprinos u umrežavanju proteina. Kao model-sistemi upotrebljeni su humani i goveđi serum-albumin. Utvrđeno je da i pored veoma male zastupljenosti SH grupe na površini ispitivanih molekula proteina (oko 80 puta manja u odnosu na ukupan broj amino- i gvanidino-grupa), ona reaguje u velikom procentu (od 25-85 %). Količina izreagovanih SH grupa i brzina reakcije, vreme uspostavljanja ravnoteže reakcije, stvaranja stabilnog proizvoda i doprinos SH grupa umrežavanju proteina zavise od koncentracije metilglioksala. Proizvod stvoren u reakciji SH grupa i nedovoljne količine metilglioksala (u odnosu na koncentraciju grupa dostupnih za modifikaciju) učestvuje u umrežavanju proteina sa značajnim udelom (4 %). U ekvimolarnoj koncentraciji sa metilglioksalom metformin sprečava njegovu reakciju sa amino i guanidino grupama albumina, ali ne i sa tiol grupom

ODREĐIVANJE ČIMBENIKA I MODELIRANJE LOGISTIKE POVRATA: TEORIJA VS. PRAKSA

Reverse logistics management has been the subject of scientific and practical attention for a few decades now. An additional interest for this topic has arisen during the last decade, due to a growing number of business entities it affects and the insight into the strategic potential of adequately managing the reverse logistics flows. Up to now, practical research and empirical confirmation regarding reverse logistics management has been scarce, and the question of defining elements, i.e. factors which determine the reverse logistics flows has remained without a complete answer. In time, various authors have tried to solve this question by setting certain guidelines and models which comprehensively show factors considered to be of key importance for the realization of the reverse logistics flows. The subject of this paper is to analyze in depth such existing models. After defining the very term of reverse logistics, the carried out model analysis respects the dynamic time component, first focusing on the theoretical model in this area- the Carter-Ellram model, and later on to the one empirically confirmed- the contemporary reverse logistics model. The aim of this paper is threefold. First, to explain the evolution of the meaning of reverse logistics. Second, to revise the two approaches which most comprehensively define the set of factors considered to be of most importance for the reverse logistics management. Thirdly, it is necessary to compare the factors identified within the theoretical model, with the ones generated empirically, in order to see the similarities and certain differences among them.Upravljanje logistikom povrata predmet je pozornosti znanstvenika i praktičara već nekoliko desetljeća unatrag. Povećani interes za ovu temu javio se posljednjeg desetljeća uslijed sve većeg broja poslovnih subjekata na koje ona utječe, kao i uvida u strateški potencijal adekvatnog upravljanja tijekovima logistike povrata. Do sada, praktična istraživanja i empirijska potvrda u pogledu upravljanja logistikom povrata bili su rijetki, a pitanje definiranja elemenata tj. čimbenika tijekova logistike povrata ostalo je bez potpunog odgovora. Protekom vremena različiti autori pokušali su riješiti ovo pitanje postavljajući određene smjernice i modele koji sveobuhvatno ukazuju na čimbenike za koje se vjeruje da su od ključne važnosti za realizaciju tijekova logistike povrata. Predmet ovog rada jest dubinska analiza takvih postojećih modela. Nakon definiranja samog pojma logistike povrata, provedena analiza modela uvažava dinamičku vremensku komponentu, prvo se usredotočujući na teorijski model u području - Carter-Ellram model, a zatim na onaj empirijski potvrđen - suvremeni model logistike povrata. Cilj ovog rada je trostruk. Prvo, objasniti evoluciju u značenju logistike povrata. Drugo, revidirati dva pristupa koja na najcjelovitiji način identificiraju čimbenike koji se smatraju od najveće važnosti za upravljanje logistikom povrata. Treće, usporediti čimbenike prvog, teorijskog modela, s onima koji su dobiveni empirijski, kako bi se vidjele sličnosti i razlike između njih

Modification of protein - SH group with α-dicarbonyl compounds: identification of products, the possibilities of determination and application in clinical practice

α-Dikarbonilna jedinjenja su veoma reaktivna, reaguju sa nukleofilnim grupama bocnih ostataka Lys i Arg, N-terminalnom amino-grupom i tiol-grupom ostatka Cys na površini molekula proteina i tako ih modifikuju. U disertaciji je ispitan doprinos tiolgrupe modifikaciji proteina metilglioksalom (MG), kinetika i konkurentnost ove reakcije u odnosu na reakcije amino- i guanidino-grupe. Nađeno je da i pored male zastupljenosti tiol-grupe na površni molekula proteina (kod HSA oko 80 puta manja u odnosu na ukupan broj amino- i guanidino-grupa) ona reaguje u velikom procentu (do 65 %), ucestvuje u umrežavanju molekula proteina (stvaranju dimera i oligomera) preko nagrađenih HSA-MG (HSA-amino-MG ili HSA-SH-MG) intermedijera sa udelom od 4% u slucaju nedovoljne kolicine metilglioksala Povecanje koncentracije metilglioksala utice na brzinu reakcije sa tiol-grupom, na vreme uspostavljanja ravnoteže, na doprinos tiol-grupe modifikaciji molekula proteina, ali ne utiče na procenat izreagovanih grupa u stanju ravnoteže (60 %), što omogucava ekstrapolaciju dobijenih rezultata na niže, fiziološke koncentracije metilglioksala. U okviru teze su razvijene spektrofotometrijske metode zasnovane na reakciji amino-grupa sa p-benzohinonom i guanidino-grupa sa reagensom koji sadrži timol i natrijum-hipobromit. Metode su precizne (RSD u opsegu 1.2-1.8 %, odnosno 0.9–2.0 %, resp.) i tačne (100.6 ± 1.2 %, 99.8 ± 0.8 %, redom), što ih cini pogodnim za kvantifikaciju ovih grupa za vreme karbonilovanja in vitro. Uticaj mikrookoline tiol-grupe na njenu reakciju sa metilglioksalom ispitan je sa aminokiselinama (Cys, NAcCys i CMC), peptidom (GSH) i proteinom (HSA). Utvrđeno je da mikrookolina –SH grupe utice na njenu reaktivnost i na prinos proizvoda reakcije. Reaktivnost tiol-grupe opada u nizu Cys>GSH>NAcCys, za sve ispitivane odnose koncentracija reaktanata. CMC ne reaguje sa metilglioksalom. Prisustvo α- amino-β-merkapto-etanske grupe u tiol-jedinjenju povecava reaktivnost tiol-grupe. Predožen je reakcioni put za reakciju Cys i metilglioksala po kome slobodna α- amino-grupa molekula Cys (cija je tiol-grupa u reakciji sa metilglioksalom vec nagradila hemitioacetal), reaguje sa slobodnom acetil-karbonilnom grupom hemitioacetala. Stvara se tiazolidinski intermedijer, koji dalje prelazi u stabilniji proizvod Cys-MG-glikozilamin...α-Dicarbonyles are reactive compounds that react with the nucleophilic groups of Lys and Arg side chains, thiol group of Cys and N-terminal amino on the protein surface, modifying them. In this thesis, the contribution of thiol group to protein modification with methylglyoxal (MG), kinetics and competitivness of this reaction with those of amino and guanidino groups reactions were inestigated. Although less abundant, thiol groups present on the protein surface (approx. 80 times lower then total number of amino and guanidino groups in HSA), are found to be reactive in considerable percentage (up to 65 %) and are participated in protein cross-linking (dimer and oligomer production), through HSA-MG intermediates (HSA-amino-MG or HSA-SH-MG), with 4% in case of unsufficient amount of MG. Increase in methylglyoxal concentration influences the reaction rate with thiol group, the time for the reaction to reach equilibrium and the contribution of thiol group to modification of proteins, yet it has no influence on the percent of reacted groups (60 %) when chemical equilibrium is reached, enabling extrapolation of the obtained results to lower, physiological concentrations of methylglyoxal. Spectrophotometric methods, based on the reaction of amino groups with pbenzoquinone and guanidino groups with thimol and sodium hypobromite reagent, have been developed. The methods are precise (RSD 1.2-1.8 % and 0.9–2.0 %, respectively) and accurate (100.6±1.2 %; 99.8±0.8 %, resp.), and therefore suitable for quantification of these groups during carbonylation process in vitro. The influence of microenviroment of thiol group on its reactivity with MG has been examined using amino acids (Cys, NAcCys and CMC), peptide (GSH) and protein (HSA). It has been shown that microenviroment of thiol group influences its reactivity and the product yield. The reactivity of thiol group decreases in the order Cys>GSH>NAcCys, for all concentration ratios examined. CMC doesn’t react with MG. The presence of α-amino-β-mercapto ethane group in thiol compound increases the reactivity of thiol group. The reaction pathway for Cys and MG reaction was proposed, in which the free α-amino group of Cys (whose thiol group is already in the form of hemithioacetale with MG) reacts with the free acetil carbonyl group of hemithioacetale..

Modeling of Neuronal Growth In Vitro: Comparison of Simulation Tools NETMORPH and CX3D

We simulate the growth of neuronal networks using the two recently published tools, NETMORPH and CX3D. The goals of the work are (1) to examine and compare the simulation tools, (2) to construct a model of growth of neocortical cultures, and (3) to characterize the changes in network connectivity during growth, using standard graph theoretic methods. Parameters for the neocortical culture are chosen after consulting both the experimental and the computational work presented in the literature. The first (three) weeks in culture are known to be a time of development of extensive dendritic and axonal arbors and establishment of synaptic connections between the neurons. We simulate the growth of networks from day 1 to day 21. It is shown that for the properly selected parameters, the simulators can reproduce the experimentally obtained connectivity. The selected graph theoretic methods can capture the structural changes during growth.Peer reviewe

Sadržaj i hemijski sastav etarskog ulja anisa

The field experiments were carried out during 2011 and 2012 in three localities in Vojvodina (Serbia) with the application of six different fertilizer regimes aimed at determining the content and composition of the aniseed essential oil. It was found that the average essential oil content of aniseed, obtained by hydrodistillation, was 3.72%. The weather conditions during the year and the locality had a statistically significant effect on the essential oil content, while different source of fertilizers was not statistically significant for the essential oil content and its composition. Essential oil composition was determined using GC–MS technique, and a total of 15 compounds were identified. It was found that the major component was trans-anethole, 94.78% on the average, and the coefficient of variation was 2%. The second most abundant component was γ-himachalene with 2.53% (CV 28%). All other components were present in less than 1%.U radu su prikazani rezultati ispitivanja količine i hemij- skog sastava etarskog ulja anisa gajenog tokom 2011. i 2012. godine na tri lokaliteta u Vojvodini (Srbija), pri primeni šest različitih vrsta đubriva. Utvrđeno je da je prosečna količina etarskog ulja u plodovima anisa dobijena metodom de stilacije vodenom parom 3.72%. Vremenski uslovi tokom godine i lokalitet imaju statistički značajan efekat na sadržaj etarskog ulja i njegov hemijski sa stav, dok primena različitih vrsta đubriva ne utiče na ove parametre. Hemij ski sastav etarskog ulja određen je primenom GC–MS analize, pri čemu je identifikovano ukupno 15 komponenti. Ustanovljeno je da je glavna komponenta transanetol, se prosečno 94,78%, i koeficijentom varijacije 2%. Druga najzastupljenija komponenta bila je γ-himahalen sa 2,53% (CV 28%). Sve ostale komponente bile su prisutne sa manje od 1%

Perspectives of the Apiaceae Hepatoprotective Effects - A Review

The liver has the crucial role in the regulation of various physiological processes and in the excretion of endogenous waste metabolites and xenobiotics. Liver structure impairment can be caused by various factors including microorganisms, autoimmune diseases, chemicals, alcohol and drugs. The plant kingdom is full of liver protective chemicals such as phenols, coumarins, lignans, essential oils, monoterpenes, carotenoids, glycosides, flavonoids, organic acids, lipids, alkaloids and xanthenes. Apiaceae plants are usually used as a vegetable or as a spice, but their other functional properties are also very important. This review highlights the significance of caraway, dill, cumin, aniseed, fennel, coriander, celery, lovage, angelica, parsley and carrot, which are popular vegetables and spices, but possess hepatoprotective potential. These plants can be used for medicinal applications to patients who suffer from liver damage

Choosing an Adequate Pesticide Delivery System for Managing Pathogens with Difficult Biologies: Case Studies on <em>Diplodia corticola, Venturia inaequalis</em> and <em>Erwinia amylovora</em>

With the challenges that negatively impact tree-based agriculture, landscapes and forests, such as climate change, plant pathogen and insect range expansion, invasive species and limited new pesticides, it is important to introduce new and effective tree protection options. In the last 20 years, pathogens that invade wood i.e. vascular tissues of trees causing wilt, yellowing, premature defoliation, cankers and tree death, have been on the rise. Diplodia corticola causes Bot canker of oak species which can kill trees diminishing the valuable ecological services they provide and reducing profits from wood and cork production. Since this and similar pathogens have difficult biologies because they reside in wood and cause severe internal damage and tree death, their management is difficult or inefficient with classical pesticide application methods that cannot reach and distribute the active ingredient in vascular wood tissues. As practical management options for this and other vascular tissue pathogens of trees are limited, we evaluated efficacy of several trunk injected fungicides in control of D. corticola and compared it with the efficacy of trunk injection of similar compounds for control of Venturia inaequalis and Erwinia amylovora, as two well-studied apple tree pathogens with different or partially similar lifestyles to D. corticola, respectively

The influence of organizational culture on supply chain integration

A team of employees that strives for the realization of a common goal is what every company needs, and the success of business depends on the way of functioning and thinking of that team. The organizational culture shapes the way employees think, react and behave. The business practice of companies in the Republic of Serbia has shown that the organizational culture oriented to employees, action and challenges is an important determinant of improving all business performance indicators, including the supply chain integration, which is the main topic of analysis within this paper. The dimensions of organizational culture affect internal integration, integration with customers and integration with suppliers, determining the generation of the key goal of supply chain management which refers to the delivery of the right product, at the right place, at the right time and at reasonable costs

Hemijski sastav etarskog ulja plodova slatkog i gorkog komorača iz Srbije

Fennel (Foeniculum vulgare Mill.) is aromatic plant from Apiaceae family. There are two types that have commercial importance, sweet fennel Foeniculum vulgare var. dulce, and bitter fennel - Foeniculum vulgare var. vulgare. The aim of this study was to examine the quality of essential oil of the fruits of these two varieties. Plants were grown in the experimental field in Mošorin for two years and from the produced fruits, essential oil was obtained by hydrodistillation method according to Clevenger apparatus, while the essential oil components were determined through GC/MS.Sweet fennel (variety 'Fino', Austrosaat AG, Austria) and bitter fennel (variety 'Vojvođanski', Dr Josif Pančić, Serbia) grown in Serbia, as most abundant compound of the essential oil had trans-anethole. In the var. dulceits part was from 77.2-80.0%, while the content of methyl-chavicol was 2.2- 2.7 %, and fenchone 3.9-5.1%. The var. vulgarehad 61.1-67.1 % trans-anethole and fenchone 22.6-26.6 % depended on the year.Komorač (Foeniculum vulgare Mill.) je aromatična biljka iz familije Apiaceae. Postoje dva varijeteta od komercijalnog značaja: slatki komorač Foeniculum vulgare Mill. subsp. vulgare var. dulce (Mill.) i gorki komorač - Foeniculum vulgare Mill. subsp. vulgare var. vulgare. Cilj ovog istraživanja bio je da se ispita kvalitet etarskog ulja plodovaova dva varijeteta. Biljke su gajene na oglednom polju u Mošorinu tokom dve godine, a iz dobijenih plodova etarsko ulje je dobijeno postupkom hidrodestilacije na aparaturi po Clevenger-u, a određivanje komponenata atarskog ulja putem GC/MS.Slatki komorač (sorta 'Fino', Austrosaat AG, Austrija) i gorki komorač (sorta 'Vojvođanski', Dr Josif Pančić, Srbija) u etarskom ulju kao najzastupljeniju komponentu je imali su trans-anetol. U varijetetu dulce njegov udeo je bio od 77,2 - 80,0 %, dok je sadržaj metil kavikola bio 2,2-2,7 %, a fenhona 3,9 - 5,1 %. Varijetet vulgare je imao 61,1 - 67,1 % trans-anetola a fenhona 22,6-26,6 % u zavisnosti od godine