1,938 research outputs found
Enzimska kinetiÄka metoda za odreÄivanje 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, Äesto propisivani neselektivni beta blokator, utvrÄeno 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, moguÄe je razviti kinetiÄku metodu za odreÄivanje propranolola. Oba sistema, enzim-supstrat-hromogen kao i enzim-supstrat-hromogen-inhibitor, okarakterisani su biohemijskim kinetiÄkim parametrima (KM, 0,326-0,330 mmol/L; Vmax, 40-42,99 Ī¼mol/L min), inhibicija je definisana kao kompetitivna i odreÄena je konstanta inhibicije 22,60 Ī¼mol/L. Da bi se u potpunosti iskoristile sve moguÄnosti predložene metode u pogledu osetljivosti, taÄnosti, preciznosti i selektivnosti, optimizovani su reakcioni uslovi. Konstruisana je kalibraciona prava, izraÄunata odgovarajuÄa jednaÄina i odreÄeni granica detekcije i kvantifikacije i to 0,004 i 0,0136 Ī¼mol/L, redom. TaÄnost i preciznost predložene metode su ispitane za tri koncentracije propranolola u oblasti kalibracione prave (0,082-21,120 Ī¼mol/L) u pet ponavljanja. TakoÄe, ispitan je uticaj veÄeg broja supstanci koje se mogu naÄi u uzorku na brzinu reakcije. Optimizovana metoda je primenjena za odreÄivanje propranolola u farmaceutskim preparatima. TaÄnost 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 naÄin 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 protoÄne injekcione metode za odreÄivanje 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 odreÄivanje hlorida gasno-difuzionom metodom otpimizovan je i primenjen za odreÄivanje hlorida u uzorcima voda sa vrlo razliÄitim sadržajem ove vrste: morskoj, vodi za piÄe i vrlo Äistim vodama u sistemu voda-para TE "Nikola Tesna B" u Obrenovcu. Upotreba amperometrijskog detektora tipa LC-17A omoguÄava snižavanje granice detekcije na 0.05 Ī¼mol/dm3 hlorida (Å”to za uzorak zapremine 0.2 cm3 iznosi 35.5 pg) i podeÅ”avanje brzine i smera toka u gasno-difuzionoj jedinici. Ovako optimizovan protoÄni sistem ima odliÄnu reproduktivnost. Za hloridni standard koncentracije 5 Ī¼mol/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 mehaniÄka 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 Äela alata. Kod dobivenih zavarenih uzoraka izvedena su dinamiÄka ispitivanja na udarnu žilavosti i odreÄene 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 speciesā 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.Ā 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
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