Application of multimarker approach to risk stratification among patients on dialysis

Introduction:The mortality rate of hemodialysis patients is very high, 10-20 times higer than in general population. Cardiovascular disease is reported to be major cause of death. By using this approach many different pathophysiological components will be covered. For validation one marker or combination of few markers as risk factors is needed to perform several statistical tests. Aim:The main goal of this thesis is to compare predictive values of ADMA as marker of endothelial dysfunction, CRP and SAA, as markers of inflammation and albumin as marker of malnutrition among patients on dyalisis,and in addition to create a common predictive value for patients with several risk factors. Methods:In this 3-years follow-up stady, plasma concentrations of ADMA and SDMA was measured by HPLC. CRP was measured using immunoturbidimetricassays; SAA was measured using immunonephalometric assays. Albumin level was obtained using standard clinical laboratory methods. Importance: The use of multimarker approach in evaluating markers of endothelial dysfunction, inflammation and malnutrion gives a new data related to risk stratification among patients on dialysis. This research shows that all markers are independent proctors of all-cause and cardiovascular cause of death. It is demonstrated that combined use of biomarkers increases the predictive power of prognostic model, whichwould improve risk stratification among patients on dyalisis.Best combination of markers for risk stratification is ADMA and albumin. Study of assessment of novel markers as risk factors contributes to better classification patients on dialysis in groups with different risk level. Therefore, management and treatment of patients on dialysis is adjusted by risk level

Aqueous extraction of anions from coal and fly ash followed by ion-chromatographic determination

Three different techniques were applied for the aqueous extraction of anions from coal and fly ash: rotary mixer-and ultrasonic-assisted extraction with different duration time, and microwave-assisted extraction at different temperatures. Validation showed that the ion-chromatographic method was suitable for the analysis of anions in coal and fly ash extracts. The variations in the amounts of anions using different extraction times during rotary-assisted extraction were minimal for all investigated anions. The efficiency of ultrasound-assisted extraction of anions from coal depended on the sonication time and was highest at 30 min. The ultrasound-assisted extraction was less efficient for the extraction of anions from fly ash than rotary-assisted extraction. Increase of temperature in the microwave-assisted extraction had a positive effect on the amounts of all anions extracted from coal and sulphate from fly ash, while the amounts of fluoride and chloride in fly ash extracts decreased. The microwave-assisted extraction of coal at 150 degrees C was compared with standard ASTM methods, and results were in good agreement only for chloride. Changes in the pH value and conductivity during ultrasound-assisted extraction were measured in order to explain changes on the surface of coal particles in contact with water and different processes that occur under environmental conditions

Ispitivanje adsorpcije fenola na makroporoznim polimernim adsorbensima

This work reports results on phenol adsorption from aqueous solution by porous copolymers based on glycidyl methacrylate: two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), were synthetized by suspension copolymerisation with ethylene glycol dimethacrylate. In addition, the two copolymer samples were functionalized with ethylene diamine. The amounts of adsorbed phenol were presented in the form of adsorptions isotherms, which were interpreted using Langmuir, Freundlich and Sips' equations. The first was found to express high level of agreement with experimental data. Phenol adsorption indicate the homogeneous distribution of active sites present on the investigated polymers. It was found that adsorption of phenol on copolymers is fast and depends on the presence of amino groups and on the pore size. From the obtained results, it was possible to distinguish macroporous polymer as a material which possesses the capacity for adsorption of phenol comparable to that of activated carbon.Ovaj rad se bavi proučavanjem adsorpcije fenola iz vodenih rastvora na kopolimerima različitih poroznih karakteristika i polarnosti. Korišćeni adsorbensi se baziraju na glicidil metakrilatu: dva uzorka makroporoznog poli(glicidil metakrilat-co-etilen glikol dimethakrilat) su sintetisani suspenzionom kopolimerizacijom sa etilen glikol dimetakrilatom. Dodatno, dva kopolimera su funkcionalizovani sa etilen diaminom. Količina adsorbovanog fenola je predstavljena u vidu adsorpcionih izotermi, koje su interpretirane korišćenjem Langmuir-ove, Freundlich-ove i Sips-ove jednačine: prva od ovih daje visok nivo slaganja sa eksperimentalnim podacima. Adsorpcija fenola ukazuje na homogenu raspodelu aktivnih mesta prisutnih u ispitivanim polimernim sistemima. Rezultati dobijeni u ovom istraživanju pokazuju da adsorpcija fenola na ispitivanim kopolimerima zavisi od prisustva amino grupa i od veličine pora. Adsorpcija fenola iz vodenih rastvora je brza u slučaju svih korišćenih adsorbenasa. Na osnovu dobivenih rezultata, može se zaključiti da su makroporozni polimeri materijali čije je adsorpcioni kapacitet za fenol uporediv sa onim koji ima aktivni ugalj

Efficacy and limitations of ChatGPT as a biostatistical problem-solving tool in medical education in Serbia: a descriptive study

Purpose This study aimed to assess the performance of ChatGPT (GPT-3.5 and GPT-4) as a study tool in solving biostatistical problems and to identify any potential drawbacks that might arise from using ChatGPT in medical education, particularly in solving practical biostatistical problems. Methods ChatGPT was tested to evaluate its ability to solve biostatistical problems from the Handbook of Medical Statistics by Peacock and Peacock in this descriptive study. Tables from the problems were transformed into textual questions. Ten biostatistical problems were randomly chosen and used as text-based input for conversation with ChatGPT (versions 3.5 and 4). Results GPT-3.5 solved 5 practical problems in the first attempt, related to categorical data, cross-sectional study, measuring reliability, probability properties, and the t-test. GPT-3.5 failed to provide correct answers regarding analysis of variance, the chi-square test, and sample size within 3 attempts. GPT-4 also solved a task related to the confidence interval in the first attempt and solved all questions within 3 attempts, with precise guidance and monitoring. Conclusion The assessment of both versions of ChatGPT performance in 10 biostatistical problems revealed that GPT-3.5 and 4’s performance was below average, with correct response rates of 5 and 6 out of 10 on the first attempt. GPT-4 succeeded in providing all correct answers within 3 attempts. These findings indicate that students must be aware that this tool, even when providing and calculating different statistical analyses, can be wrong, and they should be aware of ChatGPT’s limitations and be careful when incorporating this model into medical education

Comparison of sequential and single extraction in order to estimate the environmental impact of metals from fly ash

The aim of this paper is to simulate leaching of metals from fly ash in different environmental conditions using ultrasound and microwave-assisted extraction techniques. Single-agent extraction and sequential extraction procedures were used to determine the levels of different metals leaching. The concentration of metals (Al, Fe, Mn, Cd, Co, Cr, Ni, Pb, Cu, As and Be) in fly ash extracts were measured by inductively coupled plasma-atomic emission spectrometry. Single-agent extractions of metals were conducted at sonication times of 10, 20, 30, 40 and 50 min. Single-agent extraction with deionized water was also performed by exposing samples to microwave radiation at temperature of 50 degrees C. The sequential extraction was conducted according to the BCR procedure which was modified and applied to study the partitioning of metals in coal fly ash. The microwave-assisted sequential extraction was performed at different extraction temperatures: 50, 100 and 150 degrees C. The partitioning of metals between the individual fractions was investigated and discussed. The efficiency of the extraction process for each step was examined. In addition, the results of the microwave-assisted sequential extraction are compared to the results obtained by standard ASTM method. The mobility of most elements contained in the fly ash is markedly pH sensitive

DNA and biochemical analysis of a potential opaque2 maize population

Maize has low nutritional value because it is poor in essential amino acids lysine and tryptophan, but different mutations have been identified that increase their content. Two high lysine/tryptophan populations from Maize Research Institute genebank (IP1 and IP2) were identified in a previous research. In both populations, analysis with umc1066 opaque2 specific marker detected a recessive (o2), a dominant (O2) and an unknown allele (UA). However, IP2 lacked homozygous recessive o2o2 genotypes. The aim of the present research was to determine by DNA and biochemical analysis if UA allele was a recessive allele and/or if high tryptophan content was due to the o2 or some other mutation. Tree more opaque accessions with different mutations - IP3o5, IP4o14 and IP5floury (no data on type of mutation) were used in biochemical analysis for comparison with IP1 and IP2. Kernels were divided into two samples - with hard and with soft kernels. The UA allele sequencing revealed that it was a dominant allele with four GCCAGA repeats. SSR analysis showed presence of o2 in IP1 in both hard and soft kernels. Decrease in 22 kDa, 19 kDa and 27 kDa zeins in soft kernels was observed only in IP1 and IP2. Tryptophan content was high in soft kernels of IP1 (0.081) and IP2 (0.085), and in both hard and soft kernels of -IP3o5 (0.083 and 0.085, respectively). It can be concluded that IP1 is an o2 mutant and that IP2 carries a high tryptophan mutation other than o2, o5, o14 or floury

Investigation of different extraction procedures for the determination of major and trace elements in coal by ICP-AES and ion chromatography

This paper presents the extraction of major and trace elements from a coal sample, in deionized water, by using three different extraction techniques. Rotary mixing and ultrasonic extraction were examined for different extraction times, while the microwave-assisted extraction was performed at different temperatures. Metal concentrations (Na, K, Ca, Mg, Al, Fe, Mn, Be, Cd, Co, Cr, Hg, As, Ni, Se, Sb and Pb) in solution were determined employing inductively coupled plasma atomic emission spectrometry; whereas the results obtained for Na, K, Ca and Mg were compared employing ion chromatography. Comparing the rotary-and ultrasonic-assisted extractions, it was shown that the former technique was more efficient for the determination of Fe, Na and Pb, whereas the latter one proved more efficient for the determination of Co and Cr ions. Microwave-assisted extraction was shown to be the most efficient method for all the tested elements in coal. In addition, sequential extraction of the elements was realized using microwave digestion. The results of the sequential extraction experiments indicated associations of investigated elements with a mineral phase and organic matrix. Sequential extraction provided information on possible leaching of As, Cd, Co, Cr, Ni, Pb, Fe and Mn under environmental conditions

Canine Babesioses in noninvestigated areas of Serbia

During the years 2012-2014, a total of 158 outdoor dogs from Pančevo and Đurđevo (northern Serbia) and Niš and Prokuplje (southern Serbia) were submitted to molecular analyses (PCR and sequencing) for canine babesioses. An overall prevalence of 21.5% was found, due to the species Babesia sp. 'spanish dog' (10.1%), B. gibsoni (5.7%), B. canis vogeli (1.9%), B. caballi (1.9%), and B. microti (1.9%). In addition, sequence analysis showed the presence of Hepatozoon canis in a dog from Niš. No significant difference between infected and noninfected dogs was found by age, sex, and place of residence, whereas there was difference regarding the presence of ticks (p<0.005) and application of preventive measures such as applying of antitick drugs/devices. Moreover, a significant difference was established by area: Dogs from Prokuplje showed infection rates (59.1%) higher than dogs from Pančevo (11.9%), Niš (4.5), and Đurđevo (where infected dogs were not found), and a different geographical distribution of the species was found. The presence of so many Babesia species and the first identification of H. canis will allow investigations on the pathogenic role played by each one and suggests entomological studies on the tick species that are more suitable vectors for each of them. Finally, the presence of so many infected dogs offers the opportunity of evaluating the hypothesis of a possible zoonotic role of babesial species affecting dogs

EDUCATION AND INOVATION AS A DRIVER FOR RURAL DESTINATION DEVELOPMENT

In this paper, authors started from the hypothesis that innovations contribute to creativity and that children become more aware of in what way they can contribute to the development of rural areas. With children, play is important, and games that strengthen the imagination and encourage children to think for themselves are one of the best ways to encourage making future, strategic decisions. The challenge was to test the game “Tesla” on older school age children from 12 to 14 years old from rural areas. 138 children from five rural schools on Fruška Gora were examined. The results showed that children from rural areas, with the help of smart devices, played the game at the same level as children from any world metropolis. What’s more, through the game, the children showed awareness of the importance of the village, staying in the village and what is needed for the village to “live”

Optimization of the preparation of novel polymer/clay nanocomposites

Recent advances in material technologies have resulted in the preparation of novel polymer/clay composites with improved thermal, mechanical, optoelectronic/ magnetic properties and increased biodegradability [1]. In this study, six samples of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (PGME) nanocomposites with organically-modified montmorillonite clay Cloisite 30B® (C30B), were prepared via suspension copolymerization. In order to obtain nanocomposites with fine spherical beads of regular shape and satisfying thermal stability the optimization of the synthesis conditions was performed. Firstly, the influence of the poly(N-vinyl pyrrolidone) (PVP) quantity in the aqueous phase was varied (1, 3 and 5 wt.%) at a constant stirring rate of 250 rpm and constant clay content C30B (10 wt.%). In the second phase of the optimization of the preparation, samples with a constant composition of the composite reaction mixture (5 wt.% PVP and 10 wt.% C30B) at a stirring rate of 250, 325 and 400 rpm, were prepared. According to the obtained results, it was concluded that the optimal conditions for preparation of these composites are 5 wt.% of PVP and 400 rpm. The prepared nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in air. The structure of the prepared nanocomposites was confirmed with FTIR spectroscopy. According to the obtained SEM microphotographs the fine spherical beads, with desired size and homogeneous morphology, were prepared. Furthermore, SEM analysis was also showed that clay nanoparticles are homogeneously dispersed both inside surface and cross-section area. The incorporation of C30B clay increased the thermal stability of the prepared polymer/clay nanocomposites in comparison to the pure PGME copolymer