Abstract Hemodiafiltration is a method of treatment used to replace kidney function, which effectively removes uremic toxins of middle molecular weight from the blood of patients with the end-stage of chronic kidney disease. The aim of this study was to examine the effect of postdilution online hemodiafiltration on the degree of β2- microglobulin removal. Thirty patients treated with postdilution online hemodiafiltration were examined. The main parameter for assessing the removal efficiency of uremic toxins of middle molecular weight was the concentration of β2-microglobulin in the serum before and after a single session of postdilution online hemodiafiltration. The following tests were used for statistical analysis: Shapiro-Wilk test, Student’s T test for bound samples and Wilcoxon test. The average total convective volume is 21.38 ± 2.97 liters per session. The reduction index of β2-microglobulin during a single session of postdilution online hemodiafiltration is 70.86 ± 6.87%. The average loss of albumin during a single postdilution online hemodiafiltration is 2.50 ± 0.92 g/4h, and the albumin reduction index is 6.20 ± 2.12%. Postdilution online hemodiafiltration effectively removes β2-microglobulin from the blood of patients with end-stage chronic kidney disease. The reduction index of β2-microglobulin is ˜ 71.00% and the loss of albumin is less than 4.0 g/4h. This dialysis modality prevents the development of dialysis-related amyloidosis and atherosclerotic cardiovascular diseases in the population of patients treated with regular hemodiafiltration.

As forests in Bosnia and Herzegovina cover 2,904,600 ha or 56.7 % of its total area, and since the meteorological data analysis for the period 1961–2014 shows that the mean annual temperature maintains a continuous rise, сlose attention should be paid to these fragile ecosystems. It is important to note that one of the most economically valuable species for forestry in Bosnia and Herzegovina, Norway spruce, is particularly endangered due to its very low drought resistance and spread of various diseases. Comparing the last climate sequence (1991–2019) with the previous one (1961–1990) we found that the spruce-inhabited areas showed an average increase in the values of the Forest Aridity Index of 0.929. As for the Ellenberg’s climate quotient, it is noticeable that climate change is not as strong as in the case of the Forest Aridity Index. Based on projections for the mid- (2041–2070) and late-century (2071–2100) under the RCP 4.5, there will be no change that is likely to significantly affect the distribution of spruce. The predicted rates of decline and altitudinal shifts of favorable habitats are negligible. On the contrary, projections under the RCP 8.5 predict a significant reduction of suitable habitats, both for the existing range of Norway spruce and the entire territory of Bosnia and Herzegovina. Particularly, late-century projection under the RCP 8.5 predicts an almost complete reduction of suitable habitats, while small areas of suitable habitats at higher elevations will remain intact.

Two databases related to grassland in Bosnia and Herzegovina (B&H) have been used in this research-the Copernicus Grassland (GRA) and CORINE Land Cover (CLC). The data have been processed by using GIS tools, and the spatial distribution of grass vegetation in relation to three biogeographical and four elevation zones has been determined. By using the Copernicus Water and Wetness (WaW) database, an insight into the coverage of grass vegetation in wetlands has been obtained. In addition, the analysis of changes in databases determined the total amount and location of the largest grassland losses. Based on GRA database, B&H is one of the richest countries, with 22.4% of its territory covered by grassland. According to the CLC database, pastures occupy 6.3% and natural grasslands 5.6% of the territory of B&H. However, grassland is exposed to various anthropogenic and natural processes that affect its distribution, quality, functions, etc. The CLC database has been processed by extracting the grasslands (pastures and natural grasslands) and calculating their spatial coverage and changes which happened during the three six-year periods from 2000 to 2018. The trend of decreasing pasture areas and increasing natural grasslands has been noticed. The pastures are most endangered by the processes of conversion to other types of agricultural land, while natural grassland increased spatial coverage during the period 2012-2018 mostly due to the revitalization and grazing of burned areas in the region of Herzegovina. Grasslands have been particularly targeted for afforestation and cropland conversion at present.

The paper presents the distribution of grassland and forest vegetation in the Republika Srpska, zoning by natural regions and altitude zones and the changes that occurred in the period 2000-2018. The territory of Republika Srpska belongs to three large natural regions of different physical and geographical characteristics, with specific environmental factors that affect the distribution of vegetation. Altitude significantly affects the occurrence and types of vegetation, so a digital elevation model with a 25 m resolution was used for the analysis of vertical zonality, in order to process data on the distribution of grasslands and forests by altitude zones. Copernicus Grassland and Forest databases were used, for the period 2012-2018. Given climate change and increasing droughts, which indirectly affect the quantity and quality of vegetation, monitoring and managing grasslands and forests will be an important challenge for Republika Srpska. The results of the research show that the grassland according to the Copernicus Grassland database occupies 19.7%, and the forest vegetation according to the Copernicus Forest covers 60.1%, which is almost 80% of the territory of Republika Srpska. Grasslands are most widespread in the area of medium-high and high karst fields of eastern Herzegovina. There are more pastures in the lower altitude zones, while natural grasslands predominate in the higher zones. Forests predominate in the central mountain-valley region. Broad-leaved forests dominate at lower altitudes and coniferous forests at higher altitudes. The European program for monitoring the Earth's surface via satellite remote sensing is a new technology, so the results obtained for the territory of Republika Srpska can be considered a novelty, which is the most significant contribution of this paper.

The analysis of data from the first two decades of the 21st century shows that the area under forests in Bosnia and Herzegovina is gradually decreasing. In order to gain a detailed insight into this process, the paper will analyse the forest databases of the European satellite monitoring program Copernicus. This program, among other things, monitors the condition of forests in 39 European countries by using the High Resolution Layer (HRL). The HRL Forests database consists of 3 types of (status) products, and additional change products. The status products are available for the reference years 2012, 2015, and 2018. The status layers provide information on the Dominant Leaf Type and the Tree Cover Density at pixel level for the reference year 2018 in 10 m resolution. The Forest Type layer largely follows the Food and Agriculture Organization (FAO) forest definition. Also, the paper will use the data on forests from the CORINE Land Cover project for 2000, 2006, 2012 and 2018. The time-series includes a land change layer, highlighting changes in land cover and land use. The CLC Changes database will be analysed separately for three periods: 2000-2006, 2006-2012 and 2012-2018, due to more accurate data on forest losses. The results of the research show that forests in Bosnia and Herzegovina were reduced by 2.95%, in the period 2012-2018, where 2.55% of them were coniferous. Forests are primarily endangered by the process of conversion to transitional forest / shrub and fires.

Marko Nenadovic1, Aleksandra Nikolic2, Milica Kostovic3, Branislava Draskovic3, Milena M. Jovanovic3, Tomislav Nikolic1,3, Dejan S. Petrovic1,3 1Faculty of Medical Sciences, University of Kragujevac, Kragujevac, Serbia 2Clinic for Internal Medicine, University Clinical Centre of Kragujevac, Kragujevac, Serbia 3Clinic for Urology, Nephrology and Dialysis, University Clinical Centre of Kragujevac, Kragujevac, Serbia ORIGINALNI NAUČNI ČLANAK

Expanded hemodialysis is a method of treatment to replace kidney function, which effectively removes uremic toxins of middle molecular weight from the blood of the patients with the end stage of chronic kidney disease. Two basic principles of removing uremic toxins during an expanded hemodialysis session are diffusion and convection. The basis of diffusion is the concentration gradient, and the basis of convection is internal filtration (covective transport). Increased MCO membrane sieving capacity and high internal filtration provide high clearance of middle molecular weight uremic toxins. Expanded hemodialysis prevents the development of microinflammation, malnutrition, resistance to the action of erythropoietin, amyloidosis, accelerated atherosclerosis and atherosclerotic cardiovascular diseases in the population of patients treated with regular dialysis. The task of the nephrologist is to evaluate different dialysis modalities that are available and to select the optimal dialysis modality for the treatment of each patient individually, i.e., the individualization of dialysis treatment.

Introduction. Conventional high-flux hemodialysis effectively removes uremic toxins of medium molecular weight of 0.5-15 (20) kDa, while postdilution online hemodiafiltration effectively removes uremic toxins of medium molecular weight in the range of 0.5-60 kDa. AIM. The aim of the study was to compare the efficacy of b2-microglobulin removal from the patient serum during a single session of conventional high-flux hemodialysis and postdilution online hemodiafiltration. METHOD. Eighty-five patients treated with conventional high-flux hemodialysis and thirty patients treated with postdilution online hemodiafiltration were examined. The main parameter for assessing the removal efficiency of medium molecular weight uremic toxins was serum b2microglobulin concentration before and after a single session of conventional high-flux hemodialysis and postdilution online hemodiafiltration. The following were used for statistical analysis: Kolmogorov-Smirnov test, Student's T test and Mann-Whitney U test. RESULTS. In patients treated with postdilution online hemodiafiltration, the average total convective volume was 21.38 ± 2.97 liters per session. The b2-microglobulin reduction index for the FX CorDiax 600 dialysis membrane was 61.76 ± 7.32%, while for the FX CorDiax 800 dialysis membrane it was 74.69 ± 6.51%. The albumin reduction index for the FX CorDiax 600 membrane was 3.48 ± 1.28%, and for the FX CorDiax 800 dialysis membrane it was 6.01 ± 2.97%. There is a highly statistically significant difference between the reduction index of b2-microglobulin and albumin, for two different dialysis modalities and two different dialysis membranes (p < 0.01). CONCLUSION. Postdilution online hemodiafiltration is more efficient in removing b2-microglobulin from patient serum, compared to conventional high-flux hemodialysis. Albumin loss during a single session of high-flux hemodialysis is lower compared to a single session of postdilution online hemodiafiltration. With both dialysis modalities, albumin loss is less than 4.0 g/4h. High-flux hemodialysis effectively prevents the development of dialysis-related amyloidosis, while postdilution online hemodiafiltration effectively prevents not only the development of dialysis-related amyloidosis, but also the development of resistance to erythropoietin and atherosclerotic cardiovascular diseases in the population treated with regular dialysis.

The paper analyses the databases Urban Atlas (UA), Imperviousness, and CORINE Land Cover (CLC) for the largest cities in Bosnia and Herzegovina (B&H). The UA database contains information for five functional urban zones with more than 100,000 inhabitants: Sarajevo, Banja Luka, Tuzla, Mostar, and Zenica. The Imperviousness database is related to the subclasses of the urban atlas because the impermeability percentage has been used for a more detailed classification within the discontinuous urban area. The CLC database provides insight into the intensity of expansion of these cities during three six-year periods: 2000-2006, 2006-2012, and 2012-2018. The research has been used to analyse the expansion of urban zones, the structure, and form of cities, and the impact of urban expansion on the surrounding area. The results of the research show that, despite the negative demographic trends, there is a trend of urban expansion in B&H, mainly over the agricultural land. According to the CLC database in the period 2000-2018, artificial areas increased in spatial coverage from 1.35% to 1.7%, and urban fabric from 0.99% to 1.27%. The Imperviousness database shows that in 2018sealed areas covered 1.59% and built-up areas 0.8% of the territory of B&H. The 2013 census showed that the number of inhabitants in all five functional urban areas decreased compared to 1991, but despite that fact, the expansion of urban zones continues with a weaker or stronger intensity. So far, there has been no research on urban development based on the high-resolution layers UA and Imperviousness database in B&H, so that such research is the most significant contribution of this article.