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

Circulating Platelet Aggregates and Progression of Visual Field Loss in Glaucoma

The aim of the study was to assess a relationship between circulating platelet aggregates (CPA) and progression of visual field loss in primary open-angle glaucoma patients. CPA was determined in 27 patients with open-angle glaucoma with nonprogressive visual field loss and 15 patients with open-angle glaucoma and progression of visual field loss. Intraocular pressure (IOP) under topical therapy was <18 mmHg in all patients. CPA in glaucoma patients with progression of visual field loss was not significantly higher than those without visual field progression (p=0.59). In conclusion, our study shows that increased platelet aggregability is not solely responsible for progression of visual field loss in glaucoma patients, and indicates the role of IOP in the pathogenesis of visual field loss

Optimizacija i primena gasno-difuzione protočne injekcione metode za određivanje hlorida

A selective and sensitive procedure for the fast and indirect determination of chloride by the gas-diffusion FIA method has been optimized and applied for the determination of chloride in water samples which contained different amounts of the analyte. The examined samples were: seawater, tap water and very pure water from the water-steam system of the power plant "Nikola Tesla B" in Obrenovac. Application of an amperometric detector (model LC-17A; BAS, West Lafayette, USA) enables the detection limit to be decreased down to 0.05 mu mol/dm(3) of chloride, which col responds to 35.5 pg, and adjustment of the acceptor flow rate and direction inside the gas-diffusion unit. In this way the optimized FIA system has excellent repeatability. For 5 mu mol/dm(3) it was found to be 1.11% (n = 5). The throughput of this method is 60 samples per hour.Selektivan i osetljiv postupak za brzo, indirektno određivanje hlorida gasno-difuzionom metodom otpimizovan je i primenjen za određivanje hlorida u uzorcima voda sa vrlo različitim sadržajem ove vrste: morskoj, vodi za piće i vrlo čistim vodama u sistemu voda-para TE "Nikola Tesna B" u Obrenovcu. Upotreba amperometrijskog detektora tipa LC-17A omogućava snižavanje granice detekcije na 0.05 μmol/dm3 hlorida (što za uzorak zapremine 0.2 cm3 iznosi 35.5 pg) i podešavanje brzine i smera toka u gasno-difuzionoj jedinici. Ovako optimizovan protočni sistem ima odličnu reproduktivnost. Za hloridni standard koncentracije 5 μmol/dm3 relativna standardna devijacija iznosi 1.11 % (n = 5)

Evaluation of the Intraocular Pressure-Reducing Effect of Latanoprost as Monotherapy in Open-Angle Glaucoma

Objective of this study was to evaluate the intraocular pressure-reducing effect of latanoprost as monotherapy after replacing current dual therapy in glaucoma patients. The 6-months study comprised 189 patients with primary open angle glaucoma who were treated at least 6 months with two different kind of topical medications ( -blockers, pilocarpine, dorzolamide and brimonidine). Due to local side effects, multiple dosing regime and inadequately controlled intraocular pressure (IOP), they where switched to latanoprost 0.005% monotherapy. After switched to latanoprost, mean (IOP) was measured at baseline, after l5 days, 2 and 6 months of treatment. After six-months 178 patients had completed the study. These analyses enrolled all patients (n=189), thus, the Intention-To-Treat (ITT) results were shown instead of the results of the reduced population. IOP was clinically importantly reduced from baseline level. Five patients had uncontrolled IOP. The difference between IOP before (21.9 2.4) and after 15 days (17.4 1.7), 2 months (16.7 1.8) and 6 months (16.6 1.4) was statistically significant (p< 0.001). 90% patients has reached target IOP 18 mm. A conjunctival hyperaemia in 18 (9%), stinging and itching in 7 (4%) patients was reported. Increased iris pigmentation was seen in 3 (2%) patients. The results of this study indicate that dual therapy in open-angle glaucoma can effectively be replaced by latanoprost monotherapy in many patients

Influence of rhamnolipids, produced by Pseudomonas aeruginosa NCAIM(P), B001380 on Cr(VI) removal capacity in liquid medium

Pseudomonas aeruginosa NCAIM(P), B001380, a propitious bacterial strain isolated from mineral cutting oil was identified to be chromium tolerant and a producer of biosurfactant rhamnolipid (RL) with potential application in heavy metal bioremediation. Culture growth, RL production and Cr(VI) removal capacity of the strain in the presence of 50 mg L-1 (I) and 100 mg L-1 of Cr(VI) (II) were studied. Maximum of RL production were found in the late-stationary phase at 72 h for both Cr(VI)-amended cultures: I (236 mg L-1) and II (160 mg L-1), as well as the maximum of Cr(VI) removal capacity: 70 % (I) and 57 % (II). The amount of Cr in RL preparation II was 22 mg mg-1 determined by flame atomic absorption spectroscopy (FAAS). Appearance of a new band at 914 cm-1 in infrared (IR) spectrum of RL (II) indicated a significant proof for possible coordination of CrO42-ion with RL. The effect of Cr(VI) on monorhamnolipids (RL1) and dirhamnolipids (RL2) distribution and its ratio were studied by electrospray ionization mass spectrometry (ESI-MS). An increase was observed in a RL2/RL1 ratio for II compared to control

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

PERMANENT AND SOWN GRASSLANDS IN SERBIA: CURRENT STATE AND TRENDS

Number of cattle in Serbia during two decades of the 21st century shows the tendency of decreasing. The main source for sustainable livestock production in Serbia are grasslands. Permanent grasslands occupy approximately 30% of agricultural land in Serbia, thereby playing an important role in forage production and ecosystem services. The majority of natural meadows and pastures are located in hilly-mountainous regions. The general characteristics of grasslands in the central Balkans are low production and insufficient quality. The yield of permanent grasslands in Serbia is influenced very strongly by climatic conditions, type of grassland and level of organic and mineral fertilization. On areas that are not managed by mowing and fertilizing, forbs make up over half of the plant production.This paper presents some recent experiences and results in livestock feed production obtained from permanent and sown meadows and pastures in Serbia. There is survey of permanent grassland botanical composition and productivity with special emphasis on importance of preserving legume species. Also, recent trials assessed the benefits of mineral and organic fertilizers application in terms of forage production, testing whether the mineral or organic sources improves the stability of the grassland and evaluated response patterns over a large environmental gradient. Nutrient availability in permanent grasslands has a strong influence on plant species biodiversity, plant cover, and species’ dominance in the vegetation canopy. Dry matter yield is very low with high variation in crude protein content, which confirms that grasslands need to be maintained through fertilizer application, with special emphasis being given to the new role of manure enriched by zeolite. The above-stated lead to poor production potential of these grasslands for livestock production, nonetheless offering sustainable means of soil and biodiversity protection in the area