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

First record of the Northern brown shrimp, Farfantepenaeus aztecus (Ives, 1891) (Crustacea: Decapoda: Penaeidae) in the South Adriatic Sea, Montenegro

A single adult female specimen of the Northern brown shrimp, Farfantepenaeus aztecus, a species native to the western Atlantic coasts, was caught in Boka kotorska bay (southern Adriatic Sea) on 19 September 2013. This is the first record of this alien species in the Adriatic Sea

Vrednosti osnovnih hematoloških parametara u perifernoj krvi radnika izloženih uticaju para žive

In the present study was assessed the influence of occupational exposure to mercury vapours on the basic haematological parameters (erythrocyte, leukocyte and platelet count, haemoglobin concentration, haematocrit, MCV, MCH and MCHC). Studies were carried out on 138 workers involved in the production of chlorine using the mercuric electrolysis method (divided into three groups: permanently, periodically and earlier exposed to mercury vapours), as well as on 38 healthy workers. The shift time - weighted averages for mercury was determined in the workplace air before research; mean value was significantly over maximum tolerated dose. The mercury content in the blood and urine of exposed workers was determined by atomic absorption spectrophotometry. In all three groups 95th percentile values of mercury in blood and urine are significantly over MTD. Peripheral blood cell parameters were determined using an automatic cell counter. In the group exposed to mercury vapours, was found a statistically significant increase of erythrocyte count with a concomitant decrease in MCV. The mean values of haemoglobin concentration, MCHC and platelet count were higher in the group of workers exposed to mercury vapours, but the difference was not statistically significant. There were no significant differences in haematocrit, MCH and leukocytes between the studied groups. Our results indicate that long-term and permanent exposure to mercury vapours induces changes in the important haematological parameters of the peripheral blood.U radu je ispitivan uticaj izloženosti parama žive iz radne sredine na osnovne hematološke parametre (broj eritrocita, leukocita i trombocita, koncentraciju hemoglobina, hematokrit, MCV, MCH i MCHC). U studiju je uključeno 138 radnika koji rade u proizvodnji hlora procesom elektrolize (podeljeni su u tri grupe: stalno izloženi, povremeno izloženi i ranije izloženi uticajima para žive), kao 38 zdravih radnika. Pre studije su određene koncentracije žive u vazduhu radne sredine; srednje vrednosti su bile znatno iznad maksimalne doze tolerancije (MTD). Koncentracije žive u krvi i urinu radnika koji su izloženi živi određena je atomskom apsorpcionom spektrometrijom. U sve tri grupe je vrednost 95-tog percentila bila znatno iznad MTD. Hematološki parametri su određeni uz pomoć automatskog brojača. U grupi koja je stalno izložena parama žive, dobijeno je značajno poveć anje srednje vrednosti broja eritrocita, kao i značajno smanjenje vrednosti MCV. Srednje vrednosti koncentracije hemoglobina, MCHC i broja trombocita u grupi radnika koji su stalno izloženi uticaju žive bile su viće nego u kontrolnoj grupi, ali ta razlika nije statistički značajna. Između posmatranih grupa nije bilo značajne razlike u vrednostima hematokrita, MCH i broja leukocita. Dobijeni rezultati pokazuju da dugotrajna i stalna izloženost parama žive može da dovede do promena u vrednostima važnih hematoloških parametara

Enzimska kinetička metoda za određivanje propranolol-hidrohlorida u farmaceutskim preparatima zasnovana na njegovom inhibitorskom delovanju na holinesterazu

Propranolol, a widely used beta-blocker, inhibits the hydrolysis reaction of enzyme cholinesterase. Measurements of the difference in rate of hydrolysis rate between uninhibited and inhibited reactions allow the development of a kinetic method for its determination. Both systems, enzyme-substrate-chromogen and enzyme-substrate-chromogen-inhibitor, were characterized through biochemical kinetic parameters (K-M, 0.326-0.330 mmol/L; V-max, 40.0-43.0 mu mol/Lmin). The inhibition type was recognized as competitive and the inhibition constant, Ki, was determined to be 22.60 mu mol/L. The detection and quantification limits were calculated as 0.004 and 0.0136 mu mol/L, respectively. Accuracy and precision of proposed methods were tested. The proposed method showed good sensitivity, selectivity, simplicity and rapidity, thus it is convenient for clinical applications.Za propranolol, često propisivani neselektivni beta blokator, utvrđeno je da inhibira reakciju enzimske hidrolize butiriltioholin-jodida, koja je katalizovana serumskom holinesterazom. Merenjem razlike u brzini osnovne i inhibitorske reakcije hidrolize u prisustvu propranolola kao inhibitora, moguće je razviti kinetičku metodu za određivanje propranolola. Oba sistema, enzim-supstrat-hromogen kao i enzim-supstrat-hromogen-inhibitor, okarakterisani su biohemijskim kinetičkim parametrima (KM, 0,326-0,330 mmol/L; Vmax, 40-42,99 μmol/L min), inhibicija je definisana kao kompetitivna i određena je konstanta inhibicije 22,60 μmol/L. Da bi se u potpunosti iskoristile sve mogućnosti predložene metode u pogledu osetljivosti, tačnosti, preciznosti i selektivnosti, optimizovani su reakcioni uslovi. Konstruisana je kalibraciona prava, izračunata odgovarajuća jednačina i određeni granica detekcije i kvantifikacije i to 0,004 i 0,0136 μmol/L, redom. Tačnost i preciznost predložene metode su ispitane za tri koncentracije propranolola u oblasti kalibracione prave (0,082-21,120 μmol/L) u pet ponavljanja. Takođe, ispitan je uticaj većeg broja supstanci koje se mogu naći u uzorku na brzinu reakcije. Optimizovana metoda je primenjena za određivanje propranolola u farmaceutskim preparatima. Tačnost predložene metode je ispitana primenom metode standardnog dodatka. Predložena metoda ima dobru osetljivost, selektivnost, jednostavna je i brza, i nadasve lako dostupna, i na taj način primenljiva u velikom broju laboratorija

Microstructural evolution during friction stir welding of AlSi1MgMn alloy

This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6) obtained through the Friction Stir Welding (FSW) process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out

Mikrostrukturni razvitak AlSi1MgMn slitine tijekom zavarivanja trenjem

This paper provides the research of the influence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6) obtained through the Friction Stir Welding (FSW) process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.U radu se istražuje uticaj geometrijskih i kinematskih parametara na mikrostrukturu i mehanička svojstva zavarenog spoja od aluminijske slitine AlSi-1MgMn (6082-T6) dobivene postupkom zavarivanja trenjem (ZT). Parametri provedenih pokusa su brzina zavarivanja, kutna brzina okretanja alata, kut nagiba trna, promjer trna i promjer čela alata. Kod dobivenih zavarenih uzoraka izvedena su dinamička ispitivanja na udarnu žilavosti i određene su mikrostrukturne zone

FLOTATION KINETICS OF MAGNESIUM HYDROXIDE SEDIMENTED FROM SEA WATER

Synthetic sea water has been taken as a referential sample, in which Mg(OH)2 had been sedimented, in order to reduce biological effects and confirm reproducibility of results of the familiar composition sample. The synthetic sea water was prepared according to the scientifically developed procedure. Flotation experiments were performed in the apparatus for flotation under pressure and recoveries of floated Mg(OH)2 were determined depending on the time of flotation. The results obtained on the referential sample of the synthetic water were also tested on the sample of natural sea water and presented comparatively during work. Flotation kinetics is in most cases described by an equation of the first or second degree. However, it was established that flotation kinetics of Mg(OH)2 as chemical sediment with both types of prepared magnesium hydroxide suspension, sedimented in both the synthetic and natural sea water corresponded to the velocity of reaction n = 1.5 degree, which fully corresponds to Horst Morris’s theoretical postulates in the theory of flotation kinetics

FLOTATION KINETICS OF MAGNESIUM HYDROXIDE SEDIMENTED FROM SEA WATER

Synthetic sea water has been taken as a referential sample, in which Mg(OH)2 had been sedimented, in order to reduce biological effects and confirm reproducibility of results of the familiar composition sample. The synthetic sea water was prepared according to the scientifically developed procedure. Flotation experiments were performed in the apparatus for flotation under pressure and recoveries of floated Mg(OH)2 were determined depending on the time of flotation. The results obtained on the referential sample of the synthetic water were also tested on the sample of natural sea water and presented comparatively during work. Flotation kinetics is in most cases described by an equation of the first or second degree. However, it was established that flotation kinetics of Mg(OH)2 as chemical sediment with both types of prepared magnesium hydroxide suspension, sedimented in both the synthetic and natural sea water corresponded to the velocity of reaction n = 1.5 degree, which fully corresponds to Horst Morris’s theoretical postulates in the theory of flotation kinetics

Control Strategy of Maximum Vertical Jumps: the Preferred Countermovement Depth May Not Be Fully Optimized for Jump Height

The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost similar to 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles

Existential quest, absurd and hermeneutics of hope in Thomas Pynchon's fiction ; Экзистенциальный поиск, абсурд и герменевтика надежды в прозе Томаса Пинчона

U ovom istraživanju se analizira pet romana Tomasa Pinčona (V., Objava broja 49, Duga gravitacije, Vajnlend i Skrivena mana) sa ciljem da se ustanovi prisutnost i uloga egzistencijalističkih tema i elemenata apsurda, kao i da se ukaže na simbolička značenja određenih aspekata Pinčonove proze, koji afirmišu nadu. Ovi romani su odabrani iz kompletnog Pinčonovog stvaralaštva, jer ih povezuje istorijski kontekst, duga geneza represivnih mera američkog i evropskog društva i egzistencijalna traganja kroz postmodernističke pejsaže i simulakrume. Romani se analiziraju hronološki. Prva tri romana (V., Objava broja 49 i Duga gravitacije) se analiziraju iz ugla egzistencijalizma kako bi se izvršila identifikacija, konceptualizovanje i dešifrovanje ontološke strukture egzistencije Pinčonovih anti-junaka. Elementi apsurda i stilska sredstva izražavanja pojma apsurda ispituju se kroz analizu druga dva romana (Vajnlend i Skrivena mana). Hermeneutička rekonstrukcija pojedinih aspekata Pinčonove proze kao što su karnevalizacija, simboli porodice i zajednice, prisustvo Bele boginje i Pinčonov moto 'budi staložen a brižan' otkriva humanističku i humorističnu dimenziju njegove proze, koja otvara poseban horizont metafizičke nade...This research examines five novels of Thomas Pynchon (V., The Crying of Lot 49, Gravity's Rainbow, Vineland and Inherent Vice) in order to reveal the presence and the role of existentialist themes and the elements of absurd, as well as to specify the aspects of Pynchon's fiction with symbolic meaning, which affirm hope. These novels have been chosen from the whole Pynchon's oeuvre on account of their common historical context, the long genesis of the repressive measures of the American and European society analyzed in all of them, and the existential quests through the postmodern landscapes and simulacra, which is also a common feature. The novels have been analyzed chronologically. The first three novels (V., The Crying of Lot 49 and Gravity's Rainbow) have been analyzed from an existentialist point of view in order to identify, conceptualize and decode the ontological structure of Pynchon's anti-heroes existence. The elements of absurd and the rhetorical devices, used to express the notion of the absurd, have been examined within the analysis of the other two novels (Vineland and Inherent Vice). The hermeneutic reconstruction of certain aspects of Pynchon's fiction, such as carnivalization, the symbols of the family and community, the presence of the White Goddess and Pynchon's motto 'Keep cool but care', reveals the humanistic and humoristic dimensions of his fiction, which opens the special horizon of the metaphysical hope..