Northeast Bulgaria Research Articles

Distribution of molar incisor hypomineralization in children in Northeast Bulgaria. Severity of the dysplasia and sensitivity of the affected teeth

INTRODUCTION: Molar incisor hypomineralization (MIH) is dysplasia associated with quantitative and qualitative disturbance in the development of the hard tooth tissues, described as a separate nosological unit for the first time in 2001. The distribution of the disease is significantly different in different geographic regions and varies from 2.4% to 40% with average distribution worldwide of 12.9% affecting over 17 million people all over the world. The modern science still cannot determine its exact etiological cause so it is considered that dysplasia is an idiopathic disease. Gene mutation is discussed as an etiological factor caused by the influence of environmental factors. Other causes might be systemic diseases, infections, intoxications, and use of different medicines. AIM: The aim of the article is to investigate the distribution of MIH in relation to its severity and concomitant hyperesthesia. MATERIALS AND METHODS: A retrospective study was conducted in the University Medical Dental Center - Varna, including 1183 children, examined with a standard set of dental instruments – dental mirror, probe and pincers. The examination was done after professional cleaning and drying of the teeth. The dental status was filled out in individual ambulatory cards for each patient. RESULTS: The study investigated the distribution of MIH in Northeast Bulgaria and found that 6% of the children in the sample experienced dysplasia. In most of the cases (61%), children had all 4 permanent molars affected by it. The results supported outcomes of other studies regarding the association between the severity of the dysplasia and the presence of concomitant hyperesthesia. With the increase in the severity of MIH tooth sensitivity increases. CONCLUSION: Recent studies concerning the distribution of MIH have shown that dysplasia appears frequently in modern society. Severe hyperesthesia reflects the lifestyle and restricts the diet of children. In some cases, a radical surgical approach is considered, which may traumatize the psychological state of the child and increase the anxiety in future dental treatment.

Estimation of evapotranspiration rate by using the Penman–Monteith and Hargreaves formulas for the loess in Northeast Bulgaria complex with HYDRUS-1D

Loess and loess-like sediments cover approximately 13% of the Bulgarian territory, mainly within the Danubian plain. From the Danube River to the Fore-Balkan, the loess soils form a loess complex where its depth varies from 50–60 meters in the north to few meters in the south, respectively. Widespread loess sediments possess a specific feature: they typically form deep unsaturated zones. Quantification of the near surface water balance is extremely important for evaluating land-atmosphere interactions, and the impact of land-use change on the subsurface flow and the evapotranspiration rate is an essential term in this quantification. In the frames of a scientific project, an automatic weather station was installed in a typical plain terrain of the loess complex in Northeast Bulgaria, recording meteorological data from September 2015 to February 2017. This study provides a mathematical description of processes (i.e., Penman-Monteith and Hargreaves Methods) used to estimate daily evapotranspiration rates implemented into the numerical model HYDRUS-1D, as well as a respective rate investigation of months with and without intensive rainfalls. Overall results indicate that using the Hargreaves formula for evaluation of the potential evapotranspiration leads to overestimation between 10% and 20%, respectively for a “wet” and “dry” month.

Economic and Social Effects of the Impact of Direct and Coupled Payments on the Development of the Agricultural Sector in Bulgaria

The European programs, the direct and coupled payments for assistance and funding of the agricultural sector are part of the policy of the European Union aiming to create an opportunity for employment and active participation of the people from rural areas and to provide them with options for earning a sustainable income in these poorly urbanized locations. The direct payments form a part of the Common Agricultural Policy of the European Union and can be divided into several main types: Single Area Payment Scheme (SAPS), Redistributive Payments and Small Farmers Scheme intended to support small farms with a view to increasing the competitiveness in the field of small-scale agriculture. The purpose of this article is to analyze the economic and the social effects of the direct payments developmental impact during the first and the second programming periods. In order to achieve the present goal, an inquiry has been conducted together with a few in-depth interviews with small farmers who receive financial support in this way. The article contains the results of the inquiry involving leaseholders and farmers, conducted in North-East Bulgaria.

Sponge community of the western Black Sea shallow water caves: diversity and spatial distribution.

Marine caves possess unique biocoenotic and ecological characteristics. Sessile benthic species such as sponges associated with cave habitats typically show a marked zonation from the cave entrance towards the end of the cave. We describe three semi-submerged karstic caves of 50 to 83 m length and 936 to 2,291 m3 volume from the poorly explored cavernicolous fauna of North-East Bulgaria. We surveyed sponge diversity and spatial variability. Eight demosponge species were identified based on morphological and molecular data, of which six are known from the adjacent open sea waters of the Black Sea. Two species, Protosuberites denhartogi van Soest & de Kluijver, 2003 and Halichondria bowerbanki Burton, 1930, are reported from the Black Sea for the first time. The spatial sponge distribution inside the caves is in general similar, but shows some differences in species composition and distribution depending on cave relief and hydrodynamics. The species composition of sponges of Bulgarian caves is found to be different from Crimean caves. An updated checklist of the Black Sea sponges is provided.

Detecting local transmission of avian malaria and related haemosporidian parasites (Apicomlexa, Haemosporida) at a Special Protection Area of Natura 2000 network.

Avian haemosporidian parasites (Apicomplexa, Haemosporida) are widespread pathogens that cause malaria (Plasmodium spp.) and other haemosporidioses (Haemoproteus spp. and Leucocytozoon spp.) in birds. The Special Protection Area Durankulak Lake (SPA DL) is a coastal lake in northeast Bulgaria, part of the Natura 2000 network that was declared as important area for wintering, breeding and migratory birds. Despite a number of conservation efforts outlined for the SPAs of Natura 2000 network, the potential threats and influences of haemosporidians and other parasites on occurring birds were not considered. In the present study, we aim to investigate the richness of haemosporidian parasites in birds captured in the protected area and to report the parasite species/DNA lineages that undergo local transmission in the region. We used both microscopic examination and PCR-based methods to diagnose haemosporidian infections in juvenile (captured in the year of hatching) and adult birds. The overall prevalence of haemosporidian parasites was significantly higher in the adult birds compared to juveniles. We identified five out of 21 recorded cytochrome b (cyt b) parasite lineages that are locally transmitted in the SPA DL (one of the genus Haemoproteus Kruse, 1890 and four of genus Plasmodium Marchiafava and Celli, 1885): cyt b lineages hRW2 of Haemoproteus belopolskyi, pSGS1 of Plasmodium relictum, pCOLL1, pYWT4 and pPADOM01 of Plasmodium (Haemamoeba) spp. It is likely that the majority of the parasites with local transmission are widespread host generalists and that host exchange is rather frequent among the birds inhabiting SPA DL.

3D lithostratigraphic model of the Paleogene of the onshore part of the Moesian Platform (Northeast Bulgaria)

The Paleogene sedimentary rocks in the north-easternmost part of the territory of Bulgaria have been penetrated by numerous boreholes. In terms of regional tectonic zonation, the study area is a part of the onshore sector of the Moesian Platform, which partly includes the South Dobrogea Unit and the easternmost part of the North Bulgarian Dome with its eastern slope. The lithostratigraphy of the Paleogene successions consists of six formal units (the Komarevo, Beloslav, Dikilitash, Aladan, Avren, and Ruslar formations) and one informal unit (glauconitic marker). For compiling an overall conception of the regional aspects (lithology, thickness, spatial distribution, and relationships) of the individual lithostratigraphic units and for illustration of their spatial distribution, a 3D lithostratigraphic model based on reinterpretation of individual borehole sections has been created. The model database was compiled by integration of the original lithological data from 338 borehole sections.

Результаты исследования кремневого инвентаря из неолитического поселения Овчарово-гората (северо-восточная Болгария)

Результаты исследования кремневого инвентаря из неолитического поселения Овчарово-гората (северо-восточная Болгария)

Remote estimation of crop canopy parameters by statistical regression algorithms for winter rapeseed using Sentinel-2 multispectral images

Еstimation of crop canopy parameters is important task for remote sensing monitoring of agriculture and constructing strategies for within-field management. The main objective of this study is to evaluate the retrieval from Sentinel-2 images by parametric and non-parametric statistical models several crop canopy parameters for monitoring before winter and after winter rapeseed crop in real farming conditions of North East Bulgaria. For the calibration of the models in-situ data from three field campaigns is used. For most of the studied parameters models with good accuracy were identified, except for aboveground fresh biomass. The best identified model for vegetation fraction (RMSEcv=0.14%) and plant density (RMSEcv=9 nb/m2) were parametric models with three band vegetation index (3BSI-Tian) and linear fitting function for the first, three band vegetation index (3BSI-Verreslt) and polynomial for the second parameter. For aboveground dry biomass (RMSEcv=52 g/m²), mean plant height (RMSEcv=4cm) and nitrogen concentration in fresh biomass (RMSEcv=2%) the best models were non-parametric, Gaussian Processes Regression for the first parameter and Variational Heteroscedastic variant of the Gaussian Processes Regression for the other two.

Palynology of the upper Barremian and lower Aptian interval in parts of North Bulgaria

Upper Barremian and lower Aptian dinoflagellate cyst assemblages have been documented for the first time from five ammonite-controlled sections in Central and Northeast Bulgaria. They include important biostratigraphical markers, such as Rhynchodiniopsis aptiana, Prolixosphaeridium parvispinum, Cerbia tabulata, Lithodinia stoveri and Ctenidodinium elegantulum. The distribution of taxa is generally consistent with published palynostratigraphical schemes, but some differences are noted in this study. The best global markers for the lowermost Aptian interval are represented by the LOs of R. aptiana and C. elegantulum; however, in the sections studied, these taxa consistently occur only within the upper Barremian. The recorded overwhelming dominance of the Classopollis group, together with persistent records of pteridophyte spores, is interpreted as indicative of extremely hot and humid climate, which caused and accompanied the deposition of the OAE 1a in this part of the Tethyan Realm.

Palaeoenvironmental implications of coal formation in Dobrudzha Basin, Bulgaria: Insights from organic petrological and geochemical properties

The Dobrudzha Basin in northeast Bulgaria contains 86 coal seams distributed within three coal-bearing formations of Late Carboniferous age. This study presents the organic petrological and geochemical characteristics of coals from the Makedonka and Krupen Formations, containing some of the most prominent coal seams. These were characterized by means of proximate and Rock-Eval analyses, vitrinite reflectance measurements, organic petrography and GCMS analysis in order to establish variations in vegetation and depositional settings. Based on random vitrinite reflectance (avg. 0.7% Rr) and TOC contents (avg. ~80%, daf) the coals can be classified as low rank bituminous (high volatile B-C). Low Tmax values (avg. 430°C) further indicate a low degree of organic matter maturity. The low to moderately high ash yields, together with the presence of shaly partings, and generally low sulfur contents are consistent with peat formation in a fluviatile sedimentary environment. Petrographic analysis reveals complex maceral composition with abundant liptinite and inertinite. The predominance of detrovitrinite and the almost complete lack of strongly gelified macerals argue for enhanced humification of the plant tissues and peat formation in relatively dry environments (above water table). The distributions of n-alkanes, diterpenoids, and steranes indicate that the organic matter originated from terrestrial vascular plants. The high pristane/phytane ratios point to peat deposition under oxic conditions. Low concentrations of hopanes argue for limited bacterial degradation of the organic matter, possibly due to low pH conditions during peatification. The presence of tetracyclic diterpanes and their aromatic counterparts is attributed to pre-gymnosperm (cordaitean) input. The existence of cordaiteans, although as minor component of the palaeovegetational communities, is further evidenced by the presence of trace amounts of aromatic arborane/fernane derivatives in almost all studied samples. The occurrence of combustion-derived PAHs in all studied samples is consistent with the abundant inertinite and indicates frequent forest fires during peat formation.

Analysis of shoreline changes and cliff retreat to support Marine Spatial Planning in Shabla Municipality, Northeast Bulgaria

Measuring historical shoreline change and cliff retreat is an essential aspect of understanding the long-term geomorphic evolution of any coastal system. These data are also critical for predicting future changes and incorporating that data into proper coastal management. In recent years, Marine Spatial Planning (MSP) has increasingly been recognized as an important tool in the sustainable management of marine space across Europe and worldwide, including also issues of coastal zone management and land-sea interactions (Directive 2014/89/EU for MSP). This paper deals with investigation of the shoreline changes and cliff retreat along the 34 km section of the Black Sea coast at Shabla Municipality (Northeast Bulgaria). The study area has a low density of development and comprises large sand beaches, dunes and rapidly retreating loess cliffs. The present research was formulated under the European Union (EU) Directive for MSP in the Black Sea Basin (MARSPLAN-BS) Project. The goal was to provide reliable data and useful information in support of the development of a pilot marine spatial plan for Shabla Municipality. The study was focused on the analysis of shoreline movement (at sand beaches – erosion/accretion) and cliff retreat (at rocky coasts) utilizing a Geographic Information System (GIS). Primary data sources include topographic maps in scale 1:5,000, tachometry survey and modern Very High Resolution (VHR) orthophoto images. Change rates were determined using the Digital Shoreline Analysis System (DSAS), an ArcGIS extension for calculating shoreline change (Version 4.3), and rate-of-change statistical method. Management of coastal erosion, hard engineering methods and lack of required setbacks were discussed. Results for rates of shoreline change and cliff retreat were verified with preliminary field measurement studies and cross-checked with existing hydrodynamics, geology and geomorphology of the coast of Shabla Municipality.

Sexual dimorphism in dermatoglyphic traits and fluctuating asymmetry in Bulgarians from northeast Bulgaria

In parallel with the development of dermatoglyphics as a method of identification, data have been accumulated on the characteristics of fingerprints related to sex and ethnic origin which make up the statistical basis of this study. The aims of the present study are to determine phenotype variations in the asymmetry of dermatoglyphics in both sexes within the scope of the entire hand skin ridge system; to investigate correlations between the phenotypes; and, to assess the fluctuating asymmetry among the Bulgarian population from the region of northwest Bulgaria. The sample consists of 894 unrelated, clinically healthy individuals (480 females and 414 males) aged 18–50 years, who live in towns and villages in the northwest provinces.Finger and palmar prints were collected using rolled print (inked) method. Twenty dermatoglyphics variables of fingers and hands, separately for right and left hands and jointly for both hands, were statistically assessed. The material was processed by SPSS 12 software. The results of the present study show distinctive sexual differences. Higher values in males are recorded in finger ridge counts, the Furuhata and Cummins indices, the palm ridge counts and the overall ridge counts in all interdigital areas. Males have higher frequency values in patterns Hy, Th/III and Th/IV.

Long-term Observation of Atmospheric Pollution in an Industrial Region in North-East Bulgaria during 2000-2015: Possibilities to Improve Air Quality

Long-term Observation of Atmospheric Pollution in an Industrial Region in North-East Bulgaria during 2000-2015: Possibilities to Improve Air Quality

Mitogenomic analysis in European brown hare (Lepus europaeus) proposes genetic and functional differentiation between the distinct lineages

European brown hare is a small game species spreading across Europe to Asia Minor, with important economic traits. Population genetics studies using mitochondrial DNA markers have revealed the existence of two major phylogeographic lineages, the European and the Anatolian. European lineage is further divided in the European type halpogroup and south-eastern European type halpogroup, while Anatolian consists only by the Anatolian/Middle Eastern type halpogroup. All three haplogroups show a discrete geographical distribution, with an overlapping zone forming in North-East Greece and Bulgaria, forming a contact zone. Despite the existence of a contact zone, European haplotype was never detected in Anatolia and vice versa, proposing the presence of genetic barriers responsible for this phenomenon. In this study, we analyzed the whole mitochondrial genomes of specimens originating from both lineages, aiming to detect the genetic and functional differentiation of the oxidative phosphorylation complexes that are encoded by mtDNA that could lead gradually to the reproductive isolation of the lineages.

Book review: Raiko Krauß: Ovčarovo-Gorata. Eine frühneolitische Siedlung in Nordostbulgarien

In the first half of the 1980s, lithic materials from the prehistoric settlement of Ovčarovo-Gorata in northern Bulgaria were studied by Vietnamese archaeologist Nguyen Van Binh. At that time, he was a doctoral student in the Department of Prehistory of the National Archaeological Institute and Museum Bulgarian Academy of Sciences. In 1985, Nguyen Van Binh completed his doctoral thesis “Prehistoric flint artifact assemblages from the Late Pleistocene and Early Holocene on the basis of materials from North East Bulgaria”, which presents the results of lithic assemblages processed from the site.

Risk assessment of lead poisoning and pesticide exposure in the declining population of red-breasted goose (Branta ruficollis) wintering in Eastern Europe

The red-breasted goose Branta ruficollis is a globally threatened species (IUCN Vulnerable) and the only European goose species currently in decline. Working on the wintering grounds on the Black Sea Coast, we address two potential causes of decline of this species for the first time: lead poisoning, and contamination from pesticides. We quantified the densities of spent Pb shot in three wetlands used by the geese in north-east Bulgaria, and analysed the Pb concentration in the faeces of red-breasted geese and the more abundant greater white-fronted geese Anser albifrons, using Al concentration as an indicator of soil ingestion. Pb shot densities in sediments were low, and we found no evidence for Pb shot ingestion in red-breasted geese. On the other hand, we found that the geese were feeding on wheat whose seeds were treated with four fungicides: thiram, tebuconazole, difenoconazole and fludioxonil, and the two first were even detected in geese faecal samples. Using data on the daily food intake, we estimated the exposure levels of the geese to these fungicides, both by measuring the concentrations remaining on seeds and by estimating the amount used to coat the seeds at the time of sowing. We found that the exposure rates estimated during the sowing period for both geese species can exceed the recognized hazardous doses for thiram, and to a lesser extent for tebuconazole, which indicates that some pesticides may be playing a previously overlooked role in the decline of red-breasted geese.

Recommendation to improve the availability of medical laboratory services in general medical practice in Northeast Bulgaria

In recent years in our country there are ongoing changes in the outpatient healthcare services bound up with disbalance in the territorial distribution of medical and diagnostic structures. In this study we investigated the needs and recommendations of patients, laboratory specialists and general practitioners in outpatient healthcare in Northeast Bulgaria. The data shows significant differences between the urban and rural consumption of laboratory services and recommendations are given to improve the availability associated with the construction of mobile laboratories and detect surgery in remote locations.

Introduction and persistence of tularemia in Bulgaria

IntroductionOutbreaks of the zoonotic disease tularemia occurred in north-east Bulgaria in the 1960s. Then came 30 years of epidemiological silence until new outbreaks occurred in west Bulgaria in the 1990s. To investigate how bacterial strains of Francisella tularensis causing tularemia in wildlife and humans in the 1960s and the 1990s were related, we explored their genetic diversity.Material and methodsTen F. tularensis genomes from the 1960s (n=3) and the 1990s (n=7) were sequenced, assigned to canonical single-nucleotide polymorphism (canSNP) clades, and compared to reference genomes. We developed four new canSNP polymerase chain reaction (PCR) assays based on the genome sequence information.Results and discussionThe genetic analysis showed that the outbreaks in the 1960s as well as in the 1990s involved multiple clones and new genetic diversity. The smallest genetic difference found between any of the Bulgarian strains was five SNPs between the strains L2 and 81 isolated 43 years apart, indicating that F. tularensis may persist locally over long time periods without causing outbreaks. The existence of genetically highly similar strain-pairs isolated the same year in the same area from different hosts supports a hypothesis of local expansion of clones during outbreaks. Close relationship (two SNPs) was found between one strain isolated 1961 in northeast Bulgaria and one strain isolated 5 years before in USSR. Historical data coinciding with the actual time point describe the introduction of water rats from USSR into the Bulgarian outbreak area, which may explain the close genetic relationship and the origin of the outbreak.ConclusionGenome analysis of strains from two outbreaks in the 1960s and the 1990s provided valuable information on the genetic diversity and persistence of F. tularensis in Bulgaria.

Haemosporidian infections and host behavioural variation: a case study on wild-caught nightingales (Luscinia megarhynchos)

Haemosporidians (protozoan blood parasites) are known to modify avian hosts’ behaviour in the acute phase but not much is known about the chronic phase. We identified blood parasites by microscopy and a polymerase chain reaction (PCR)-based method in a sample of 22 wild-caught nightingales (Luscinia megarhynchos) in northeast Bulgaria. We compared non-infected and infected birds in single behavioural traits under the hypothesis that infected birds should show more risk-taking behaviours and quicker exploration. Infected nightingales were more prone to risk-taking and this behavioural trait was significantly correlated with the intensity of infection. However, no differences were found in exploration speed or body condition and reactions to a stressful situation (weight change in captivity, handling), which might be due to either a lack of differences or the limited sample size.

Degree of associations among vectors of the genus Culicoides (Diptera: Ceratopogonidae) and host bird species with respect to haemosporidian parasites in NE Bulgaria.

The occurrence of haemosporidians in biting midges of the genus Culicoides is examined in North-East Bulgaria in order to reveal their potential role for parasite transmission. A PCR-based technique amplifying part of the mitochondrial cytochrome b gene of the parasite is applied on naturally infected biting midges. Totally, 640 parous individuals of four species and 95 blood-fed individuals of six species of Culicoides are examined for the presence of DNA of haemosporidians. Haemosporidian genetic lineages are identified in individuals of three insect species: Culicoides alazanicus (12 lineages, nine lineages of Haemoproteus and three lineages of Plasmodium), Culicoides festivipennis and Culicoides circumscriptus (with two and one lineages of Haemoproteus, respectively). Two genetic lineages of Haemoproteus are recorded in more than one vector species. These results demonstrate variations in the specificity of Haemoproteus genetic lineages to their potential vectors, since some lineages are recorded in a single vector species and others occur in two or more vector species.