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Introduction/Objective. Vitamin D not only plays a role in calcium and phosphorus metabolism, but also has antiproliferative, prodifferentiation, anti-inflammatory and immunomodulatory effects. The aim of this study was to investigate the association between vitamin D deficiency in individuals with autoimmune Hashimoto’s thyroiditis. Methods. A total of 156 patients were enrolled and divided into two groups. First group included 108 patients with 25 (OH) D insufficiency, and second included 48 individuals with normal 25 (OH) D levels. All participants underwent a detailed clinical examination, laboratory tests for thyroid function [T3, fT4, TSH, thyroid antibodies (TPO-Ab, and TG-Ab)], as well as ultrasound scanning (thyroid volume and Doppler characteristics). Results. The patients with vitamin D insufficiency (n = 108 (69.2%)) were predominantly female and had a higher body mass index than the patients with normal vitamin D levels. The group with vitamin D insufficiency had statistically significantly higher TSH levels. The prevalence of positive thyroid antibodies was higher in the vitamin D insufficiency group, while thyroid volume, superior thyroid artery, and inferior thyroid arteries resistance index, as well as the prevalence of positive circular dichroism signals, were significantly higher in the vitamin D insufficiency group. Out of the 156 subjects, 44 were diagnosed with thyroiditis (28.2%). The mean serum level of 25 (OH) D was statistically notably lower in patients with thyroiditis (20.23 ± 8.10 ng/mL) than in the group without thyroiditis (25.44 ± 8.38 ng/mL), p < 0.001. Conclusion. There was an association between vitamin D insufficiency and hypothyroidism in subjects with Hashimoto’s thyroiditis.

The issue of rural tourism service quality does not retain a sufficiently important place in the existing domestic and foreign literature. The purpose of this research in service quality, which is an important initiator of tourist satisfaction and loyalty in rural tourism. The survey was conducted at the beginning of 2020 using a questionnaire-based survey method to 299 respondents. With the purpose of checking the impact of the service quality on the satisfaction and loyalty of tourists in rural tourism of Šumadija and Western Serbia, an analysis was performed using SEM-Structural Equation Modeling. The survey results point there is a direct correlation between service quality and satisfaction, and as well between loyalty and satisfaction. Between service quality and loyalty there is not a direct link, but there is a large indirect effect by satisfaction. The implications of this research, limitations and future research recommendations for are outlined.

Introduction: The process of recording a patient includes a procedure with several separate segments during work that together provide the imaging to be obtained for adequate radiological analysis. Throughout the process, it is possible to experience errors that create artifacts on X-rays which ultimately results in an inadequate recording that is not for valid analysis. Aim: Determine the total number of radiological films that are not for valid analysis. Sort out and analyze errors in radiographs according to the work process. Provide recommendations for improving the quality in the process of recording the patient. Material and methods: A prospective study was conducted at the Radiology Clinic of the Clinical Hospital Center Pristina-Gracanica, for two calendar years. All films that are not for valid analysis were considered. The radiological procedure of patient imaging was broken down into logical segments so that possible errors could be observed. We have summarized the causes of the artifacts in five appropriate groups (errors made by the recording technique, during the acquisition of the image, caused by the object of recording, during the processing of films in an automated machine and improper handling of films). Results: The total amount of used X-ray films is 32600 pieces, of which 242 (0.74%) were errors and artifacts. The most common format of a film with an error or artifact was 30x40 cm. A frequency of errors according to the cause of the occurrence is classified into appropriate groups. The largest number was in a group 1 - 155 (64.04%), in a group 2 - 3 (1.24%), in a group 3 - 13 (5.37%), in a group 4 - 67 (27.69%), and in a group 5 - 4 (1.66%). Conclusion: In the proper systematization of all observed errors and artifacts of X-ray film, it allows us to realise the place of error during the whole process of recording and processing of the film. We hereby wish to propose their elimination and improve the quality of the radiology department.

Introduction: The circle of Willis is the major source of collateral blood flow between the carotid and vertebrobasilar system. Its potential depends on the presence and size of arteries that vary greatly among normal individuals and therefore their adequate observation by a radiologist is necessary. Aim: Determine the type of the circle of Willis and their frequency. Determine the type, frequency and localization of anatomical variants of arteries, as well as their average diameter. Compare these variables according to the age and gender of the examinees. Material and methods: A retrospective study was performed at the Center for Radiology of the Clinical Center Nis during 2017. All subjects underwent CT or MR angiography according to a standard endocranial protocol. The anterior and posterior parts of the circle were specially observed, with an emphasis on the presence or absence of anatomical variants of the arteries, with the measurement of their diameter. The obtained data were classified into variants of the front or rear part of the ring as well as the type of ring according to integrity. The frequency of these variables and their comparison by sex and age were measured. Results: The research included 92 examinees. According to the configuration of the Willis arterial ring, the adult type was the most often represented (71.7%). The most common type in terms of integrity was partially complete. The most common anatomical variants obtained in our work was aplasia of AcoA (27.2%) and aplasia of one or both PCoA (21%). PcoA hypoplasia was occured in women with a frequency of 13.5% while in men it was not present. Conclusion: Adequate understanding of the morphology of the circle of Willis by radiological methods is a good guide for neurosurgical and radiological intervention procedures. In this way, potentially significant neurological complications and the risk of morbidity and mortality could be reduced.

Introduction: The most common causes of renal artery disease are stenosis, as a consequence of atherosclerosis and fibromuscular dysplasia. Computed tomographic (CT) angiography is a non-invasive method, which enables visualization of vascular structures and walls of blood vessels, as well as morphology of the renal parenchyma. Objective: To determine the importance of CT angiography in detecting the cause and degree of renal arterial disease. Methods: A total of 45 patients were included in the cross-sectional study conducted from March 2017 to March 2019 in the KBC DR Dragiša Mišović-Dedinje, Belgrade, Serbia. Criteria for inclusion were suspicion of secondary arterial hypertension, patients in preparation for kidney transplantation and in the follow-up period after transplantation, as well as patients with suspected traumatic lesions. We analyzed the causes of the disease, the morphology of the blood vessel wall, the percentage of stenosis, and the renal parenchyma. Results: The most common causes of renal arterial disease are atherosclerosis, which was found in 33 (73%) patients, renal artery aneurysm was found in 5 (11%) subjects, fibromuscular dysplasia in 4 (8.9%) and trauma in 1 (2) , 3%) of the patient. There were 10 (22.2%) patients with a significant (average 80 ± 14.5%) degree of stenosis. The sensitivity of CT angiography in the detection of atherosclerotic changes in the renal arteries was 87.9%, while the sensitivity of CT angiography in the detection of fibromuscular dysplasia was 75%. A statistically significant correlation was found between atherosclerotic stenosis of the renal arteries and a positive CTA finding (p = 0.0002). Conclusion: CT angiography is an important method of visualization and quantification of pathological changes in the renal arteries.

Introduction: Glaucoma diagnosis is based on consideration of several factors, such as increased intraocular pressure (IOP), damage to the optical disc, and associated visual field loss. Evaluation of the integrity of the corneal endothelium and monitoring of the corneal thickness is indispensable during the preoperative preparation for phacoemulsification. These data are of great importance for later treatment and monitoring of early and late postoperative complications. Objective: The aim of this study was to determine the central corneal thickness immediately before and after cataract surgery in patients with primary glaucoma (open and closed angle), comparing them with patients who do not have diagnosed glaucoma. Materials and methods: A prospective study covered a total of 159 subjects who performed cataract surgery by the method of phacoemulsification with the implantation of the intraocular lens in the posterior chamber at the Clinic for Eye Diseases at the Clinical Center of Serbia in Belgrade in 2017 and 2018. Pre-operative patients are classified into two groups. The first group with a primary glaucoma consisted of 71 respondents, with an open angle 41 with glaucoma, and a closed angle glaucoma 30. The second group consisted of people who did not have a diagnosed glaucoma, 88 of them. The central corneal thickness was measured using an ultrasound pachymeter. The measurements were made before the operation, 24 hours, 10 and 30 days after the operation, trying to get all done at the same time of day. Results: Between patients without glaucoma (BG), primary open-angle glaucoma (POAG) and primary glaucoma of closed angle (PACG), there is a statistically significant difference in median age (χ2 = 10.102; DF = 2; p = 0, 006). Among the observed groups there were statistically significant differences in the values measured preoperatively (χ2 = 10.265; DF = 2; p = 0.006). Among the observed groups, there was no statistically significant difference in the values measured in the first postoperative day (χ2 = 4.364; DF = 2; p = 0.099), nor in the 10th postoperative day (χ2 = 3.250; DF = 2; p = 0.197); 30 days after surgery (χ2 = 1.427; DF = 2; p = 0.490). In each of the groups individually, the appearance of oedema or a very statistically significant difference in the first and tenth postoperative day. Statistically significant difference was present 30 days after surgery, but far less compared to early postoperative period. Conclusion: Based on the values obtained in this prospective study, we estimate that monitoring of corneal thickness has a mandatory place in the observation of patients after cataract surgery. We found that there is no difference in preoperative measurement only between groups without glaucoma and open angle glaucoma. Measurements performed in the first, tenth, thirtieth day do not differ in groups, but edema restitution in the 30-th day was observed in all observed groups.

Introduction: The presence of malignant altered axillary lymph nodes, and their timely detection is crucial for staging and prognosis of breast cancer. Echotomographic examinations are widely used technique, and represents one of the first tests of diagnostic modalities. Classic B mode, Doppler sonography, and MicroPure testing technique, allow a comprehensive assessment of the detailed morphology and internal structure of the nodes (number, location, size, shape, borders, echogenicity, edema of the surrounding soft-tissue, the presence of microcalcifications), and determination of their nature. Objective: The aim is to determine the role of echotomographic review the morphology, determining the nature and setting guidelines for diagnostic testing algorithm for malignant altered axillary lymph nodes. Materials and methods: This cross-sectional study included 212 echotomographic tested axillary lymph nodes in the Department of Radiological Diagnostics KBC 'Dr Dragisa Mišović-Dedinje' in Belgrade, in the period from February 2016.do March 2017. All patients were examined in the supine position with arms in abduction, and external rotation. The following parameters: shape, size, and homogeneity of the echo-structure, edge, an auxiliary structures such as intranodal necrosis, edema and peripheral vascularization, as well as the presence of microcalcifications, using classical B mode, Doppler sonography and MicroPure technique. For all examinations we used Toshiba device, Aplio XG, 10MHz linear transducer. Results: Of a total of 212 tested nodule, histopathology was also verified 44 malignantly changed (21%), 4 of which the primary (9%) in a patient with Hodgkin's lymphoma, and secondary 40 (91%) in patients with breast cancer. Other nodes 168 (79%) were normal-reactive. The best performance in the echotomographic examinations are the criteria of: the shape (longitudinal cross-ratio

Introduction: Radiological diagnostics is the dominant diagnostic discipline in medicine. The level of technical equipment of radiological departments directly affects many aspects of importance for the diagnosis of a large number of pathological conditions and, therefore, the progress in the treatment of patients. Aim: The research analyzes the existing situation in radiological cabinets on the territory of AP Kosovo and Metohija. Particularly important elements will be analyzed for the functioning of the radiology service. An analysis of the obtained results gives recommendations in order to improve radiological diagnostics. Methods: A survey was conducted to obtain relevant data. A questionnaire consisting of segments containing basic elements for determining patients' accessibility criteria, equipping the cabinet with equipment and employing professional staff was designed. This formulated questionnaire was sent to radiological departments in health institutions on the territory of AP of Kosovo and Metohija, which are part of the Ministry of Health of the Republic of Serbia. Results: The highest percentage of radiological equipment is represented in KBC Kos. Mitrovica and KBC Pristina-Gračanica, a total of 54%. The percentage of medical staff is at KBC Kos Mitrovica radiologist 50%, work technician 36%. This is followed by KBC Prishtina-Gračanica with 25% radiologists and 27% of radiological therapists. Conclusion: The basics of radiological diagnosis are conventional x-ray techniques. Tertiary health care does not adequately possess radiological high-tech modes of computerized tomography and magnetic resonance. Staff training is required in order to re-establish existing knowledge and skills development that are followed by the continuous professional development of technology applied in radiological practice.

The quality of employees' work in the tourism industry depends primarily on their job satisfaction. This has directed the subject of the research in this paper to examine the impact of employee satisfaction on tourist satisfaction with the services of spa tourism in the Republic of Serbia. Research was conducted using the survey method, the questionnaire technique, in Lukovska Spa, based on a sample of 125 respondents, of which 55 were employees and 70 tourists / guests in hotels 'Jelak' and 'Kopaonik'. The most important finding of the research is related to the correlation between the employee satisfaction and the tourist satisfaction with the quality of service in Lukovska Spa, which confirmed the hypothesis of the direct and positive impact of employee satisfaction on the tourist satisfaction with the quality of services. Employee satisfaction has a positive impact on the quality of the service, which directly affects the tourist satisfaction with the quality of the services provided.

Introduction/Objective. Compression, also called strain elastography imaging techniques, represent new echotomographic modality, which is a promising method for the differentiation of benign from malignant lesions, not only in the thyroid gland but also in other organs. The objective of this study is to evaluate the importance of compression elastography in the differentiation of benign and malignant thyroid nodules. Methods. We performed echotomographic examinations in B mode, and examinations using compression elastography in a total of 186 persons (152 females and 34 males, with the average age of 45.3 ± 13.5 years), with 264 nodules in the thyroid gland. Elastography was done in two steps: the first one through scoring elastographic figures, and the second one through the determination of the resistance index (strain ratio – SR). Results. Using elastography scores by Fukunari, 44 of 60 malignant nodules had a score of 3–4, while 152 of the 204 benign nodules had a score of 1–2. Using the receiver operating characteristic (ROC) analysis, the best cut-off point obtained using elastography scores was 2, with a sensitivity of 73.3% and specificity of 74.5%. Using the software-calculated SR we found that out of 89 nodules with SR ≥ 2.5, 52 were malignant nodules, while out of 175 nodules with SR < 2.5, 167 were benign nodules. Using the ROC analysis, the best cut-off point obtained using SR was > 2.5, with a sensitivity of 86.7%, and specificity of 81.9%. Conclusion. As a follow-up of standard echotomographic examination in B mode, compression elastography is a newly developed and promising technique in the differentiation of benign from malignant lesions. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 175030]

Tourism is one of the largest industries in the world, based on information, modern information and communication technologies and the Internet are basically one of the most effective ways to exchange any information. Modern information and communication technologies have contributed to significant innovations in tourism, which affect the digitalization and modernization of the entire tourism industry and infrastructure, and is often referred to as electronic tourism. The aim of this paper is to show that the modern information and communication technologies have become the support of many critical functions in the tourism and travel industry to provide innovative and useful tools, whereby companies whose business is tourism can boost their presence in the global tourism market.

Background/Aim. All the functions of the digestive system are controlled, guided and initiated by the autonomic nervous system. A special part of this system placed in the wall of the gastrointestinal tract is known as the enteric or metasympathetic nervous system. The aim of this study was to analyse myenteric nervous plexus in different parts of the digestive tract. Methods. We examined the myenteric nervous plexus of the esophagus, stomach, duodenum, jejunum, ileum, transverse colon and rectum in tissue samples taken from 30 cadavers of persons aged 20-84 years. After standard histological processing sections were stained with hematoxylineosin, cresyl violet (CV) and AgNO3 method. Multipurpose test system M42 was used in morphometric analysis. The results were analyzed by t-test and analysis of variance. Results. The number of neurons per cm2 surface was the lowest in the esophagus (2.045 ± 310.30) and the largest in the duodenum (65,511 ± 5,639). The statistical processing showed significant differences (p < 0.001) in the number of neurons between the esophagus and all other parts of the digestive tract. The maximal value of the average surface of the myenteric nervous plexus neurons was observed in the esophagus (588.93 ± 30.45 μm2) and the lowest in the stomach (296.46 ± 22.53 μm2). Conclusion. There are differences in the number of ganglion cells among different parts of the human digestive tract. The differences range from a few to several tens of thousands of neuron/cm2. The myenteric nervous plexus of the esophagus was characterized by a significantly smaller number of neurons but their bodies and nuclei are significantly larger compared to other parts of the digestive tract.

Tourism is a dynamic economic activity that request an constant innovation. As one aspect of innovation in tourism are certainly modern information and communication technologies. In this paper, attention is focused on mobile commerce in tourism, the role and significance of WAP as an application protocol and mobile application 'online booking'. This paper presents the development and deployment of mobile applications, 'online booking' through which companies whose business tourism can access the mobile commerce to improve their services, satisfying the needs of mobile users of third generation (tourists) to achieve a better market position, reduce costs, increase turnover (sales), all in order to increase profits and greater profits.

Introduction: Aging is a continuous process, which leaves its mark on all tissues, organs and organ systems. The aging process causes a number of functional and morphological and structural changes in the kidneys. Objective: The aim of our study was to analyze echotomographic changes in the size of the renal parenchyma and renal sinus during the aging process. Method: The study was conducted on 62 subjects in the service of the radiological diagnostics of CHC Dr Dragisa Mišović in Belgrade. All subjects included in this study were neither anamnestically nor echotomographically positive for any of kidney diseases. Subjects were assorted in three age groups. Group I (20-39 years) - 21 subjects, group II (40-59 years) - 21 subjects, and group III (60-79 years) - 20 subjects. Results: During aging process dimensions of the renal parenchyma decrease. Dimensions of the renal parenchyma exhibit statistically significant difference (p

CT diagnosis of peritoneal space is a complex part of the scan and it is difficult to introduce on axial sectionsbecause it is normal in a curved plane. The presence of 'blurred' or 'misty' mesentery, is the most common sign of the presence of pathological processes in the peritoneal cavity. Normal subperitoneal fat is low attenuation measurements, and any increase in the attenuation of these structures (from -60 to 0 HU) diagnostic is important. The aim of this study was to evaluate the role computerized tomography in the exploration and visualization of pathological changes in the mesentery. The study of prevalence on 28 patients was performed CT examination of the abdomen and pelvis within the Department of Radiological Diagnostics KBC 'Dr Dragisa Mišović-Dedinje' in Belgrade. We used a standard protocol recording the abdomen, based on testing by dynamic protocol by Rossi. All recording were performed at 16-slice scanner. In 18 of total 28 people (64%), saw the changes on mesentery, which were inflamantory origin, of which changes according to the type of 'misty' mesentery were recorded in 6 people with pancreatitis (33%), in 4 people with appendicitis (22%) in 7 persons with diverticulitis (39%), while in one there was panniculitis with pseudocapsule in the form of fat ring (6%). In the two people (7%), there was a 'misty' mesentery as a result of thrombosis of the superior mesenteric vein, while the 2 persons (7%), mesentery was altered as a result of hemorrhagic ischemia of the small intestine. One person (4%) had pathologically altered due to the mesentery of the small intestine primary tumors (carcinoid), and in 5 people (18%) were present as a result of adhesion sequelae after surgical intervention and radiation therapy. The sensitivity of CT diagnostics for obtaining positive results in people who have an inflammatory changed mesentery was 90% and specificity of the method was 87.5%, positive predictive value 94.7% and negative predictive value of 77.8% and a diagnostic accuracy 89. 3%. Based on the high values of sensitivity and specificity of the test examination in this study section, CT diagnosis of peritoneal space is required place in the diagnostic algorithm. Thanks to the multidetector scanners has been extended exploration peritoneal space, but despite the large contribution of software solutions, meticulousness in the review, as well as a high level of knowledge are essential assumptions to work, a review of these areas is always a diagnostic challenge.

The term 'acute myocardial infarction ' is used when there is evidence of myocardial necrosis in a situation when the clinical picture suggests myocardial ischemia. Average per year in the world of acute myocardial infarction fall ill 6 million people, lethality occur in over 25% of cases. Identification of the most important epidemiological characteristics of myocardial infarction in the Serbian areas of Kosovo and Metohija. In paper we used an epidemiological cross sectional study (cross -sectional). During the period of 2004-2011 in Kosovo and Metohija (Serbian areas) reported a total of 421 patients with acute myocardial infarction . The ratio of male patients compared to the number of female patients is 2,69:1 . The largest number of patients (92) and the highest non-standardized incidence rate of acute myocardial infarction (59.13/100000 population) are registered in 2008th year. Incidence of acute myocardial infarction showed a statistically significant correlation with patients ' age and gender (chi-square=21.39 , df=1 , p

Introduction: In adults the diagnosis of acute pyelonephritis and glomerulonephritis is primarily based on clinical and laboratory-biochemical testing. In patients where the clinical picture atypical, even if a person does not respond to therapy resorts to radiographic examination. Echotomographic examination is unavoidable in the diagnostic algorithm. Objective: The aim of this study was to establish the individual echotomographic parameters, as well as to determine their diagnostic power in patients with acute infections (pyelonephritis and glomerulonephritis), and comparing them with the appropriate reference tests. Materials and methods: We performed a cross sectional study in the period from October 2014. until May 2015. It included 50 patients with acute inflammation of the kidney which was made echotomographic examination of the abdomen and pelvis, within the Department of Radiological Diagnostics KBC 'Dragisa Mišović-Dedinje' in Belgrade. The echotomographic examination of the kidneys included testing of numerous parameters that could indicate the existence of an acute inflammation of the kidney. For the gold standard, we take the findings obtained by CT (computed tomography) imaging of the abdomen and pelvis, as well as histopathological findings obtained by fine needle bio-psy. Results: At 50 patients with acute inflammation of the upper urinary tract, 41 patients (82%) had acute pyelonephritis, and 9 (18%) had acute glomerulonephritis. In 70% of patients with acute pyelonephritis (29 people) were present enlargement of the kidney where the test sensitivity was 79.3% and specificity of 91.7%. The accuracy of the method was 82.9% when the monitored parameters: loss of central echo complex and cortico-medullary differentiation. The sensitivity of the test in which the observed thickening of the pelvic and ureteric wall was 65% and specificity of 90%. The analysis of the presence of calculus in renal parenchyma leads to the values of sensitivity test of 54.8% and specificity of 80%. Hypoechoic focus in the renal parenchyma, enlargement of the kidneys and loss corticomedullar limits are parameters who with great sensitivity and specificity suggest acute glomerulonephritis. Conclusion: On the basis of high values of sensitivity and specificity of the test survey estimates that ultrasound has a required place in the following diagnostics algorithm. The use of echotomography that offer the possibility of high resolutive views, as well as the wide availability and good reproducibility of the method, the low cost of inspection, in favor of the first exploration ultrasound examination. Multidetector CT scan and fine needle biopsy remains the method of choice for the definitive diagnosis.

E-tourism is a consequence of the emergence of new technologies which emergence made possible the emergence and rapid development of Internet. This paper presents a model of B2B business as a solution through which companies whose business tourism accesses to e-tourism. B2B e-business model is the business of a company with other companies in the region. As a B2B model is implemented dealer service, which gives companies engaged in tourism over the Internet to conduct their business, sell their vouchers to other companies (dealers) and travel agencies in a very fast and easy way to reduce their costs. B2B has become something without which companies will not be able to work if they want to stay on top.

In the diagnostic algorithm, abdominal ultrasound is not the method of choice in detecting malignancies of the colon. However, in practice, with unclear clinical symptoms and without hemoccult test, abdominal ultrasound is often the first step in the diagnosis. Our experience indicates that abdominal ultrasound, as the first diagnostic method, gives good results in the detection of colon tumor mutation. The aim of this study was to evaluate the role of echotomography, as the first diagnostic method in detecting colon cancer. During the past six months, in the Department of Diagnostic Radiology University Hospital 'Dr Dragisa Mišović' in 14 patients were detected tumors the colon. In 11 patients, abdominal ultrasound was first applied diagnostic method. All patients made a Hemoccult test, CT of the abdomen and pelvis and endoscopy with biopsy. The histopathological findings corresponded to adenocarcinoma. Ultrasound diagnosis is performed on the camera brand Toshiba. Echotomographicaly in 11 of the 14 patients it was observed a thickening of the colon wall, with suspected characters infiltration of the wall. Solid mass, hypo-heteroehogenog looks were observed in 11 patients, vague form of the intestinal lumen in 9 patients, the jagged edges of a suspected infiltration in 6 patients, the air trapped in the tumor (pseudotumor) weight in 6 patients, pathologically altered regional lymph nodes were observed in 3 patient, and the presence of the distal scattering diseases, in the form of secondary deposits in the liver, in 4 patient. Tumor mass greater than 5 cm was observed in 8 patients. Sensitivity of this performed echotomographic diagnosis was 78.6%, specificity 83.3%, positive predictive value 68.7%, negative predictive value of 89.3%, while the accuracy of the diagnosis made was 81.8%. Echotomography as the first diagnostic step, contributing to establishing the final diagnosis. It is important in evaluation of diagnostical and therapeutical cost-benefit, with shorter diagnostic treatment, which leads to endoscopy, and in the clinical assessment of the ex­tent of the underlying disease, considering insufficient availability of CT examinations in our conditions.

The paper presents a business plan internet tourism companies "MS", a new venture which is focused on improving the company's business in the online business, through the development of the tourist site and accessing electronic business and trade elektrkonskoj. This internet business plan giving details of the proposed construction, together with the expected needs and results, taking into account the unique nature of e-business. It notes that the company can take advantage of e-business and e-commerce in order to increase the efficiency of your business.

This paper treats the elastic stability of three-segment stepped column that is subjected to axial concentrated compressive forces using the strain energy method. Efforts have been made to establish the methodology for the development of a model that is useful for quick, yet quite accurate, estimation of the elastic buckling critical load. By using the load, segments stiffness and lengths ratios, the dimensionless influence coefficient is defined for any combination of parameters. The diagrams of critical load based on geometric parameters variation are given. The results of analytical model are compared with numerical results obtained from finite element method. Within two investigation regimes, influences of bending stiffness and lengths variations are analyzed separately.

Changes in electrophoresis pattern after interaction of supercoiled plasmid pBR322 DNA with avarol was studied at a micromolar concentration of reactants under mild reaction conditions. Interactions of avarol with linear high-molecular CT-DNA at millimolar concentrations were analyzed by electrophoresis and UV spectrophotometry. It was observed that avarol is capable of quenching ethidium bromide fluorescence in DNA bands. An increase in the absorbance of DNA was detected. The results indicate the binding of avarol to DNA and/or modification of nucleotide bases.

The quinone avarone, isolated from the marine sponge Dysidea avara, possesses the ability to chemically modify proteins. In this work, modification of lectin isolated from the coral Gerardia savaglia by avarone was examined. The techniques used for studying the modification were: SDS PAGE, isoelectric focusing and hemagglutination testing. The results of the SDS PAGE indicate dimerization of the protein. A shift of the pI toward lower value occurs upon modification. The change of the hemagglutination activity of the protein confirms that chemical modification of G. savaglia lectin by avarone changes its ability to interact with the membrane of erythrocytes.

The sterol composition of two green algae and two brown algae from the South Adriatic was determined. In the green alga Ulva lactuca, the principal sterols were cholesterol and isofucosterol. In the brown alga Cystoseira adriatica, the main sterols were cholesterol and stigmast-5-en-3ß-ol, while the characteristic sterol of the brown algae, fucosterol, was found only in low concentration. The sterol fractions of the green alga Codium dichotomum and the brown alga Fucus virsoides contained practically only one sterol each, comprising more than 90 % of the total sterols (clerosterol in the former and fucosterol in the latter).

The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of β-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10)-estradiene- 1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of β-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein occurs. It could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pI of the protein (5.4) upon modification toward lower values (from pI 5.0 to 5.3) indicated that lysine amino groups are the principal site of the reaction of β-lactoglobulin with the quinones.

The regioselectivity of the reaction of conjugate addition of thiols amines, methanol and hydrogen chloride with the monoalkyl-1,4-benzoquinones avarone and 2-tert-butyl- 1,4-benzoquinone was investigated. It was shown that the regioselectivity of the reaction is influenced by the electrophilicity of position 5 in unprotonated 2-alkylquinones, the increased electrophilicity of position 6 in acidic medium, and by the acidity of the intermediate hydroquinones.

Interaction of liquid with ultra-hydrophobic surface is accompanied by creation of layer of air. The effect of the air film has a potential of use in industry in many applications. The quality of the surface is influenced by matrix roughness, the character of physical or chemical cover. There was developed a method for analysis of the liquid flow and the air film using the lighting in volume, visualization with CCD camera and long distance microscope, and optical filters. There were prepared four stainless steel samples of inner channel of dimensions (80 × 8 × 8) mm and initial surface roughness Ra 0.33, Ra 1.0, Ra 2.0, and Ra 2.2. The inner channel was treated with plasma and commercial hydrophobic coating Greblon (WEILBURGER Coatings GmbH). There was realized study focused on the liquid flow velocity profile close to the air film. There are present results for laminar, transient and turbulent flows. The study also estimated the air film thickness depending on the Re number. The knowledge of the air film behaviour helps applied suitable degree of processing and cover for the target application.

The MO study showed that the radical oxidation of phenols into quinols occurs readily. Further radical oxidation (in the m-CPBA/(BzO)2/hv system) of quinols occurs through appropriate biradical species with an activation energy of 79.5 kJ/mol yielding syn-epoxyquinols. The stereochemical outcome presented in this study is in full agreement with the experimental results.

Several NADH model compounds, N-alkyl-1,4-dihydronicotinamides, some of them possessing amphiphilic properties, have been synthesized, and the kinetics of their reaction with a biologically active liphophilic quinone, avarone, has been studied in a protic solvent both in the presence and absence of cationic, anionic or non-ionic surfactants. In the absence of micellar agents, the medium- and long-chain N-dodecyl (3) and N-heptadecyl (4) derivatives show a significant increase in the reaction rates compared to other model compounds, due to the stabilization of the semiquinone intermediate. Anionic surfactants retard the reaction, non-ionic surfactants slightly accelerate the reaction with the short-chain derivatives, and retard the reaction with the medium- and long-chain derivatives, and the cationic surfactants increase the reaction rate with all derivatives except the long-chain 4. The results support the e-p-e mechanism of the reduction of lipophilic quinones byNADHmodels in protic medium.