Teaching accounting in higher education of tourism: comparative analyses: Bulgaria (private-public) / Russia (private-public) higher education institutions

Forty-five years after the end of World War II, Bulgarian education and science were closely related with the Russian model. After the end of 1989 in the Bulgarian education been done processes away by the Russian system and the adoption of European models; there was private universities. This reflected and on the system of teaching of accounting in all economic specialties. In 2003 Russia joined the Bologna process too and with these started again and now activated the afresh process of contacts between the two educational systems, the exchange of students, teachers and scientists. However, a number of leading universities in Russia want to keep maintaining the tradition of the Russian system of education. The aims of this study are to present a comparison between the teachings of accounting in programs of tourism in high schools in both national educational systems, which is the interest in terms of status, which reached after they change over the past 20 years. The study issued also the system of teaching of accounting courses in tourism specialties of higher education institutions in both countries and in the public and private high schools. Keywords: teaching accounting in higher tourism education, fundamental and applied accounting knowledge, regulation. JEL classification: M41, M48, L83, A

Examining the mechanism of action of small-molecule negative allosteric modulators of the human chemokine receptor CXCR2

The CXC chemokine receptor 2 (CXCR2) is a G protein-coupled receptor (GPCR) with key functions in neutrophil trafficking and activation both during normal homeostasis, and in acute and chronic inflammation. In addition, CXCR2 signalling promotes tumour survival through the mediation of cell proliferation and metastasis, angiogenesis and immune suppression. Despite the therapeutic potential of inhibiting CXCR2 for the treatment of inflammatory conditions and cancer, there is currently not an approved treatment at the receptor. This is largely due to the challenging task of balancing the successful treatment of inflammation or cancer suppression whilst maintaining the homeostatic function of the immune system intact when blocking CXCR2 (Cheng et al., 2019a). There are a range of structurally distinct negative allosteric modulators (NAMs) of CXCR2 compounds that bind to the receptor at an intracellular pocket overlapping with the site of G protein coupling. Two compounds – navarixin and AZD5069 remain in clinical trials as combination therapies for the treatment of cancer. These compounds, in particular, have been reported to have slow dissociation kinetics at CXCR2. This thesis generated new approaches to explore the in vitro pharmacology of candidate CXCR2 NAMs, in particular to understand their mechanism of action in more depth. A number of key questions were identified to address – first, the ability of NAMs to regulate CXCR2 signalling through different effector proteins (e.g. arrestins as well as G proteins); second, the extent to which different NAMs can regulate CXCR2 conformation and modulate chemokine binding, as well as blocking effector coupling; and third, the extent to which NAM binding kinetics at the intracellular site, as well as the allosteric nature of the mechanism, influenced the functional profile of their antagonism over time. First, we co-expressed the human CXCR2 receptor tagged C- terminally with the LgBiT fragment, and β-arrestin2 and mini Gαo effectors with the SmBit fragment of the Nanoluciferase enzyme to generate a luciferase complementation assay (NanoBiT) for CXCR2-effector interactions in stably transfected HEK293 cells. These assays provided live-cell real time readouts of the agonist chemokine CXCL8 activation, and the effects over time of NAM inhibition. For the range of NAM pharmacophores explored, these approaches demonstrated their equivalent inhibition of both mini G protein and arrestin receptor interactions. We also identified differences among the NAMs in their ability to supress the basal receptor activation and in the surmountability of their effects. Using mathematical modelling approaches and comparison of close homologues (enantiomers) of navarixin, NAMs functional effects were attributed to their binding kinetics properties showing that slow koff NAMs insurmountably supress receptor-effector interactions, due to the insufficient time of binding equilibrium to be established. In contrast, fast koff NAMs promoted rightward shifts in the CXCL8 concentration-response curves likely due to negative binding cooperativity between the NAM and the orthosteric agonist. Next, a commercially available AF647 labelled CXCL8 peptide was used to establish a non-radiolabelled CXCR2 binding assay format via both imaging and TR-FRET methodologies, applicable in whole-cells and in membrane preparations. NAMs fully inhibited tracer binding at CXCR2 in high sodium- conditions suggesting stabilisation of the inactive receptor conformation and apparently mutually exclusive binding of the NAM and chemokine, despite the difference in their topography of binding sites. Under conditions in which receptor transition to an active conformation would be better promoted (low sodium), an allosteric effect of NAM inhibition was demonstrated, and an influence on labelled chemokine dissociation kinetics measured in the real time homogeneous TR-FRET assay. In developing novel receptor-effector interaction and fluorescent ligand approaches applicable to real time studies of binding and signalling, these results provide new information on the action of intracellular NAMs at the CXCR2 receptor. Key findings include the ability of NAMs to prevent CXCR2 coupling with multiple effectors, and a role for NAMs in allosteric modulation of chemokine affinity through conformational selection (supported by recent structural studies) – as well as steric blockade of effector interaction. Finally, our data reveal the importance of slow binding kinetics, as well as non-competitive interactions in generating insurmountable inhibition – a feature of CXCR2 antagonism which may be beneficial under inflammatory conditions involving a cytokine storm. This increased understanding may aid future in vitro optimisation of CXCR2 NAM compounds, to titrate the desire for blockade that is therapeutically effective while managing the risk of side effects

WELLNESS AT SCHOOL BY PRACTICING CHEERLEADING

The issue for the health of children and youth, their physical culture, and motor activity is becoming increasingly relevant in Bulgarian society. Physical education and sports (PES) and a healthy lifestyle are factors that support young people's adaptation to new living conditions, opposing the continuously complicated health and environmental situation. This material analyses the place of Cheerleading in the third lesson of the discipline “Physical Education and Sport” at school. The beneficial effects of regular activities are established, and it is positioned to be included in the "Gymnastics and Dance" module under the category of "other". Overall, incorporating cheerleading into a school wellness program can have a range of benefits for students, from improving physical fitness to promoting social and emotional wellbeing. It is important to ensure that safety protocols are in place and that cheerleading is practiced in a safe and supervised environment. Cheerleading can be a fun and engaging way for students to stay active and promote wellness at school

Mitochondrial DNA Suggests a Western Eurasian origin for Ancient (Proto-) Bulgarians

Ancient (proto-) Bulgarians have long been thought to as a Turkic population. However, evidence found in the past three decades show that this is not the case. Until now, this evidence does not include ancient mitochondrial DNA (mtDNA) analysis. In order to fill this void, we have collected human remains from the VIII-X century AD located in three necropolises in Bulgaria: Nojarevo (Silistra region) and Monastery of Mostich (Shumen region), both in Northeast Bulgaria and Tuhovishte (Satovcha region) in Southwest Bulgaria. The phylogenetic analysis of 13 ancient DNA samples (extracted from teeth) identified 12 independent haplotypes, which we further classified into mtDNA haplogroups found in present-day European and Western Eurasian populations. Our results suggest a Western Eurasian matrilineal origin for proto-Bulgarians as well as a genetic similarity between proto- and modern Bulgarians. Our future work will provide additional data which will further clarify proto-Bulgarian origins; thereby adding new clues to current understanding of European genetic evolution

Effect of the Predecessor and the Nitrogen Rate on Productivity and Essential Oil Content of Coriander (Coriandrum sativum L.) in Southeast Bulgaria

Received: May 31st, 2022 ; Accepted: August 13th, 2022 ; Published: September 19th, 2022 ; Correspondence: [email protected] (Coriandrum sativum L.) is one of the most important essential oil crops on a global scale. Coriander productivity is determined by the genotype, the environmental factors, as well the agronomic practices. A field experiment was conducted in Southeast Bulgaria during three vegetation seasons (2015, 2016, and 2017). The present study aimed at analysing the influence of two crop predecessors (winter wheat and sunflower) and four nitrogen (N) levels (0, 40, 80, and 120 kg ha-1 ). Productivity elements, seed yield, and seed essential oil content of coriander (cv. Mesten drebnoploden) were under evaluation. The results obtained showed that winter wheat was a more suitable predecessor of coriander in comparison to sunflower. The highest results regarding the number of umbels per plant, the umbel’s diameter, the number of umbellets per umbel, the number of seeds per umbel, the seed weight per plant, the 1,000 seed mass, as well as the seed yield for the rate of 80 kg ha-1 of N were recorded. The highest essential oil content after applying 120 kg ha-1 of N was established. Increasing the N level from 0 to 120 kg ha-1 led to a positive and significant effect on essential oil yield. No significant differences between the N rates of 80 and 120 kg ha-1 were recorded. The received results contributed for the evaluatation of the optimum nitrogen level, as well as for the determination of a more suitable predecessor of coriander in order to obtain the highest yield of better quality in the region of Southeast Bulgaria

Enhancing postharvest quality of fresh-cut plums with chitosan-grape seed oil edible coatings

Edible coatings are traditionally used to improve food appearance and conservation due to their environmentally friendly nature. In this study fresh cut (halved and pitted) plum (var. Stanley) fruits were coated by chitosan grape-seed-oil (GsO) nanoemulsion. Physical, physico-chemical, microbiological and sensorial properties were examined 3 times during 9 d refrigeration storage. The control probes wasted their safety and quality after the 4th d. The coated probes preserved their quality and safety to the end of the storage period. The fruits with chitosan coating showed smaller microbiological contamination but the chitosan GsO coated fruits showed higher values in the sensorial parameters. The coated samples preserved their sensorial parameters up to 80% on the 9th d

Y-Chromosome Diversity in Modern Bulgarians: New Clues about Their Ancestry

To better define the structure and origin of the Bulgarian paternal gene pool, we have examined the Y-chromosome variation in 808 Bulgarian males. The analysis was performed by high-resolution genotyping of biallelic markers and by analyzing the STR variation within the most informative haplogroups. We found that the Y-chromosome gene pool in modern Bulgarians is primarily represented by Western Eurasian haplogroups with , 40% belonging to haplogroups E-V13 and I-M423, and 20% to R-M17. Haplogroups common in the Middle East (J and G) and in South Western Asia (R-L23*) occur at frequencies of 19% and 5%, respectively. Haplogroups C, N and Q, distinctive for Altaic and Central Asian Turkic-speaking populations, occur at the negligible frequency of only 1.5%. Principal Component analyses group Bulgarians with European populations, apart from Central Asian Turkic-speaking groups and South Western Asia populations. Within the country, the genetic variation is structured in Western, Central and Eastern Bulgaria indicating that the Balkan Mountains have been permeable to human movements. The lineage analysis provided the following interesting results: (i) R-L23* is present in Eastern Bulgaria since the post glacial period; (ii) haplogroup E-V13 has a Mesolithic age in Bulgaria from where it expanded after the arrival of farming; (iii) haplogroup J-M241 probably reflects the Neolithic westward expansion of farmers from the earliest sites along the Black Sea. On the whole, in light of the most recent historical studies, which indicate a substantial proto-Bulgarian input to the contemporary Bulgarian people, our data suggest that a common paternal ancestry between the proto-Bulgarians and the Altaic and Central Asian Turkic-speaking populations either did not exist or was negligible