Applications of biaryl cyclization in the synthesis of cyclic enkephalin analogs with a highly restricted flexibility.

A series of 10 cyclic, biaryl analogs of enkephalin, with Tyr or Phe residues at positions 1 and 4, were synthesized according to the Miyaura borylation and Suzuki coupling methodology. Biaryl bridges formed by side chains of the two aromatic amino acid residues are of the meta-meta, meta-para, para-meta, and para-para configuration. Conformational properties of the peptides were studied by CD and NMR. CD studies allowed only to compare conformations of individual peptides while NMR investigations followed by XPLOR calculations provided detailed information on their conformation. Reliability of the XPLOR calculations was confirmed by quantum chemical ones performed for one of the analogs. No intramolecular hydrogen bonds were found in all the peptides. They are folded and adopt the type IV ß-turn conformation. Due to a large steric strain, the aromatic carbon atoms forming the biaryl bond are distinctly pyramidalized. Seven of the peptides were tested in vitro for their affinity for the µ-opioid receptor.

Non-uniform sampling of similar NMR spectra and its application to studies of the interaction between alpha-synuclein and liposomes.

The accelerated acquisition of multidimensional NMR spectra using sparse non-uniform sampling (NUS) has been widely adopted in recent years. The key concept in NUS is that a major part of the data is omitted during measurement, and then reconstructed using, for example, compressed sensing (CS) methods. CS requires spectra to be compressible, that is, they should contain relatively few "significant" points. The more compressible the spectrum, the fewer experimental NUS points needed in order for it to be accurately reconstructed. In this paper we show that the CS processing of similar spectra can be enhanced by reconstructing only the differences between them. Accurate reconstruction can be obtained at lower sampling levels as the difference is sparser than the spectrum itself. In many situations this method is superior to "conventional" compressed sensing. We exemplify the concept of "difference CS" with one such case-the study of alpha-synuclein binding to liposomes and its dependence on temperature. To obtain information on temperature-dependent transitions between different states, we need to acquire several dozen spectra at various temperatures, with and without the presence of liposomes. Our detailed investigation reveals that changes in the binding modes of the alpha-synuclein ensemble are not only temperature-dependent but also show non-linear behavior in their transitions. Our proposed CS processing approach dramatically reduces the number of NUS points required and thus significantly shortens the experimental time.

High-Resolution X-ray Absorption and Emission Spectroscopy for Detailed Analysis of New CO2 Methanation Catalysts.

A new approach for the characterization of CO2 methanation catalysts prepared by thermal decomposition of a nickel MOF by hard X-ray photon-in/photon-out spectroscopy in form of high energy resolution fluorescence detected X-ray absorption near edge structure spectroscopy (HERFD-XANES) and valence-to-core X-ray emission (VtC-XES) is presented. In contrast to conventional X-ray absorption spectroscopy, the increased resolution of both methods allows a more precise phase determination of the final catalyst, which is influenced by the conditions during MOF decomposition.

NMR studies of inclusion complexes: naphthalene and natural cyclodextrins.

Inclusion complexes of naphthalene (NP) with cyclodextrins (CD) have been investigated so far using non-NMR techniques resulting in inconsistent data. Here, the first application of high-field NMR spectroscopy in combination with a precise analysis of the results has allowed us to determine accurately the stoichiometry of complexes and their association constants. Titration measurements have been performed by 1H NMR spectroscopy in D2O at a magnetic field B0 of 18.8 T. NP and αCD form a 1 : 2 complex in which a single NP molecule is closed in a capsule made up of two αCD macrocycles. NP and ßCD build coexisting 2 : 1 and 2 : 2 complexes with large binding constants. Larger γCD host molecules form essentially similar complexes with NP as the ßCD but corresponding binding constants are smaller.

The influence of OSPE and PBL on competency-based pharmacy student self-assessment.

BACKGROUND: In addition to vocational education and experience, the pharmaceutical profession's proper pursuit requires acquiring and continuously improving professional competencies. In recent years, the need has been increasingly highlighted for developing a medical education system based on helping students develop their competencies. It is necessary to adapt the tools and methods for assessing competencies during formal education. It will enable students to know the directions of further personal or professional development. OBJECTIVE: The study aimed to compare pharmacy students' self-assessment outcomes before and after the Objective Structured Practical Examination (OSPE), which finished the Pharmaceutical Care course (PCc). The study's purpose was also to compare the outcomes of the self-assessment of competencies between the students of two academic years for whom classes on the PCc were provided by different methods. METHODS: The study was conducted over two academic years (2018/2019 and 2019/2020) among 5th-year students enrolled at the Faculty of Pharmacy of the Jagiellonian University Medical College (JUMC) at the end of the Pharmaceutical Care course. Different teaching methods were used in the delivery of the course in these academic years. The students self-assessed their competencies using a questionnaire consisting of a list of personal and patient care competencies. The students completed the questionnaire before and after the OSPE, which followed the completion of the PCc. RESULTS: Students' professional competencies as self-assessed after the exam were higher than those assessed before the exam. Differences were observed in both personal and patient care competencies. Students taking the course in the 2019/2020 academic year set their pre-OSPE competencies higher than students taking the PCc in 2018/2019. CONCLUSION: The self-assessment scores increased for most competencies included in the study following the OSPE. This may suggest that taking part in the exam, involvement in patient's case simulations, and self-assessment of performance at individual stages of the exam contributed to increased subjective assessment of professional competencies.

Medical students' perception of e-learning approach (MeSPeLA) - a mixed method research.

There is a discrepancy between the research exploring e-learning at medical universities in Central/Eastern and Western European countries. The aim of the MeSPeLA study was to explore the understanding, experience and expectations of Polish medical students in terms of e-learning. Questionnaire containing open-ended and closed questions supplemented by focus group discussion was validated and performed among 204 medical students in Poland before COVID-19 pandemia. Several domains: understanding of e-learning definitions; students' experience, preferences, expectations and perceptions of e-learning usefulness, advantages and disadvantages were addressed. The qualitative data were analyzed using an inductive approach. 46.0% of students chose a communication-oriented definition as the most appropriate. 7.4% claimed not to have any experience with e-learning. 76.8% of respondents indicated they had contact with e-learning. The main reported e-learning advantages were time saving and easier time management. The most common drawback was limited social interactions. The acceptance of the usage of e-learning was high. Medical undergraduates in Poland regardless of the year of studies, gender or choice of future specialization showed positive attitudes towards e-learning. Students with advanced IT skills showed a better understanding of the e-learning definition and perceived e-learning to be a more useful approach. The expectations and perceptions about e-learning in Polish medical schools seems similar to some extent to that in Western European and the United States so we can be more confident about applying some lessons from these research to Poland or other post-communist countries. Such application has been accelerated due to COVID-19 pandemia.

Rh(I)/(III)-N-Heterocyclic Carbene Complexes: Effect of Steric Confinement Upon Immobilization on Regio- and Stereoselectivity in the Hydrosilylation of Alkynes.

Rh(I) NHC and Rh(III) Cp* NHC complexes (Cp*=pentamethylcyclopentadienyl, NHC=N-heterocyclic carbene=pyrid-2-ylimidazol-2-ylidene (Py-Im), thiophen-2-ylimidazol-2-ylidene) are presented. Selected catalysts were selectively immobilized inside the mesopores of SBA-15 with average pore diameters of 5.0 and 6.2 nm. Together with their homogenous progenitors, the immobilized catalysts were used in the hydrosilylation of terminal alkynes. For aromatic alkynes, both the neutral and cationic Rh(I) complexes showed excellent reactivity with exclusive formation of the ß(E)-isomer. For aliphatic alkynes, however, selectivity of the Rh(I) complexes was low. By contrast, the neutral and cationic Rh(III) Cp* NHC complexes proved to be highly regio- and stereoselective catalysts, allowing for the formation of the thermodynamically less stable ß-(Z)-vinylsilane isomers at room temperature. Notably, the SBA-15 immobilized Rh(I) catalysts, in which the pore walls provide an additional confinement, showed excellent ß-(Z)-selectivity in the hydrosilylation of aliphatic alkynes, too. Also, in the case of 4-aminophenylacetylene, selective formation of the ß(Z)-isomer was observed with a neutral SBA-15 supported Rh(III) Cp* NHC complex but not with its homogenous counterpart. These are the first examples of high ß(Z)-selectivity in the hydrosilylation of alkynes by confinement generated upon immobilization inside mesoporous silica.

Temperature as an Extra Dimension in Multidimensional Protein NMR Spectroscopy.

NMR spectroscopy is a particularly informative method for studying protein structures and dynamics in solution; however, it is also one of the most time-consuming. Modern approaches to biomolecular NMR spectroscopy are based on lengthy multidimensional experiments, the duration of which grows exponentially with the number of dimensions. The experimental time may even be several days in the case of 3D and 4D spectra. Moreover, the experiment often has to be repeated under several different conditions, for example, to measure the temperature-dependent effects in a spectrum (temperature coefficients (TCs)). Herein, a new approach that involves joint sampling of indirect evolution times and temperature is proposed. This allows TCs to be measured through 3D spectra in even less time than that needed to acquire a single spectrum by using the conventional approach. Two signal processing methods that are complementary, in terms of sensitivity and resolution, 1) dividing data into overlapping subsets followed by compressed sensing reconstruction, and 2) treating the complete data set with a variant of the Radon transform, are proposed. The temperature-swept 3D HNCO spectra of two intrinsically disordered proteins, osteopontin and CD44 cytoplasmic tail, show that this new approach makes it possible to determine TCs and their non-linearities effectively. Non-linearities, which indicate the presence of a compact state, are particularly interesting. The complete package of data acquisition and processing software for this new approach are provided.

Fundamental Characterization, Photophysics and Photocatalysis of a Base Metal Iron(II)-Cobalt(III) Dyad.

A new base metal iron-cobalt dyad has been obtained by connection between a heteroleptic tetra-NHC iron(II) photosensitizer combining a 2,6-bis[3-(2,6-diisopropylphenyl)imidazol-2-ylidene]pyridine with 2,6-bis(3-methyl-imidazol-2-ylidene)-4,4'-bipyridine ligand, and a cobaloxime catalyst. This novel iron(II)-cobalt(III) assembly has been extensively characterized by ground- and excited-state methods like X-ray crystallography, X-ray absorption spectroscopy, (spectro-)electrochemistry, and steady-state and time-resolved optical absorption spectroscopy, with a particular focus on the stability of the molecular assembly in solution and determination of the excited-state landscape. NMR and UV/Vis spectroscopy reveal dissociation of the dyad in acetonitrile at concentrations below 1 mM and high photostability. Transient absorption spectroscopy after excitation into the metal-to-ligand charge transfer absorption band suggests a relaxation cascade originating from hot singlet and triplet MLCT states, leading to the population of the 3 MLCT state that exhibits the longest lifetime. Finally, decay into the ground state involves a 3 MC state. Attachment of cobaloxime to the iron photosensitizer increases the 3 MLCT lifetime at the iron centre. Together with the directing effect of the linker, this potentially makes the dyad more active in photocatalytic proton reduction experiments than the analogous two-component system, consisting of the iron photosensitizer and Co(dmgH)2 (py)Cl. This work thus sheds new light on the functionality of base metal dyads, which are important for more efficient and sustainable future proton reduction systems.

Determination of Crystal-Field Splitting Induced by Thermal Oxidation of Titanium.

The electronic structure of transition-metal oxides is a key component responsible for material's optical and chemical properties. Specifically for metal-oxide structures, the crystal-field interaction determines the shape, strength, and occupancy of electronic orbitals. Consequently, the crystal-field splitting and resulting unoccupied state populations can be foreseen as modeling factors of the photochemical activity. Herein, we study the formation of crystal-field effects during thermal oxidation of titanium in an ambient atmosphere and range of temperatures. The X-ray absorption spectroscopy is employed for quantitative analysis of average t2g-eg crystal-field splitting (Δoct) and relative t2g/eg bands occupancy. The obtained result shows that Δoct changes as a function of temperature from 1.97 eV for a passive oxide layer created on a Ti metal surface at room temperature to 2.41 eV at 600 °C when the material changes into the TiO2 rutile phase. On the basis of XAS data analysis, we show that the Δoct values determined from L2 and L3 absorption edges are equal, indicating that the 2p1/2 and 2p3/2 core holes screen the t2g and eg electronic states in a similar manner.

Structure, Biosynthesis, and Biological Activity of Succinylated Forms of Bacteriocin BacSp222.

BacSp222 is a multifunctional peptide produced by Staphylococcus pseudintermedius 222. This 50-amino acid long peptide belongs to subclass IId of bacteriocins and forms a four-helix bundle molecule. In addition to bactericidal functions, BacSp222 possesses also features of a virulence factor, manifested in immunomodulatory and cytotoxic activities toward eukaryotic cells. In the present study, we demonstrate that BacSp222 is produced in several post-translationally modified forms, succinylated at the ε-amino group of lysine residues. Such modifications have not been previously described for any bacteriocins. NMR and circular dichroism spectroscopy studies have shown that the modifications do not alter the spatial structure of the peptide. At the same time, succinylation significantly diminishes its bactericidal and cytotoxic potential. We demonstrate that the modification of the bacteriocin is an effect of non-enzymatic reaction with a highly reactive intracellular metabolite, i.e., succinyl-coenzyme A. The production of succinylated forms of the bacteriocin depends on environmental factors and on the access of bacteria to nutrients. Our study indicates that the production of succinylated forms of bacteriocin occurs in response to the changing environment, protects producer cells against the autotoxicity of the excreted peptide, and limits the pathogenicity of the strain.

Dynamic 15N{1H} NOE measurements: a tool for studying protein dynamics.

Intramolecular motions in proteins are one of the important factors that determine their biological activity and interactions with molecules of biological importance. Magnetic relaxation of 15N amide nuclei allows one to monitor motions of protein backbone over a wide range of time scales. 15N{1H} nuclear Overhauser effect is essential for the identification of fast backbone motions in proteins. Therefore, exact measurements of NOE values and their accuracies are critical for determining the picosecond time scale of protein backbone. Measurement of dynamic NOE allows for the determination of NOE values and their probable errors defined by any sound criterion of nonlinear regression methods. The dynamic NOE measurements can be readily applied for non-deuterated or deuterated proteins in both HSQC and TROSY-type experiments. Comparison of the dynamic NOE method with commonly implied steady-state NOE is presented in measurements performed at three magnetic field strengths. It is also shown that improperly set NOE measurement cannot be restored with correction factors reported in the literature.

Changes in heart morphometric parameters over the course of a monocrotaline-induced pulmonary arterial hypertension rat model.

BACKGROUND: Aim of this study was to assess changes in cardiac morphometric parameters at different stages of pulmonary arterial hypertension (PAH) using a monocrotaline-induced rat model. METHODS: Four groups were distinguished: I-control, non-PAH (n = 18); II-early PAH (n = 12); III-end-stage PAH (n = 23); and IV-end-stage PAH with myocarditis (n = 7). RESULTS: Performed over the course of PAH in vivo echocardiography showed significant thickening of the right ventricle free wall (end-diastolic dimension), tricuspid annular plane systolic excursion reduction and decrease in pulmonary artery acceleration time normalized to cycle length. No differences in end-diastolic left ventricle free wall thickness measured in echocardiography was observed between groups. Significant increase of right ventricle and decrease of left ventricle systolic pressure was observed over the development of PAH. Thickening and weight increase (241.2% increase) of the right ventricle free wall and significant dilatation of the right ventricle was observed over the course of PAH (p < 0.001). Reduction in the left ventricle free wall thickness was also observed in end-stage PAH (p < 0.001). Significant trend in the left ventricle free wall weight decrease was observed over the course of PAH (p < 0.001, 24.3% reduction). Calculated right/left ventricle free wall weight ratio gradually increased over PAH stages (p < 0.001). The reduction of left ventricle diameter was observed in rats with end-stage PAH both with and without myocarditis (p < 0.001). CONCLUSIONS: PAH leads to multidimensional changes in morphometric cardiac parameters. Right ventricle morphological and functional failure develop gradually from early stage of PAH, while left ventricle changes develop at the end stages of PAH.

Metal Exchange in the Interprotein ZnII -Binding Site of the Rad50 Hook Domain: Structural Insights into CdII -Induced DNA-Repair Inhibition.

CdII is a major genotoxic agent that readily displaces ZnII in a multitude of zinc proteins, abrogates redox homeostasis, and deregulates cellular metalloproteome. To date, this displacement has been described mostly for cysteine(Cys)-rich intraprotein binding sites in certain zinc finger domains and metallothioneins. To visualize how a ZnII -to-CdII swap can affect the target protein's status and thus understand the molecular basis of CdII -induced genotoxicity an intermolecular ZnII -binding site from the crucial DNA repair protein Rad50 and its zinc hook domain were examined. By using a length-varied peptide base, ZnII -to-CdII displacement in Rad50's hook domain is demonstrated to alter it in a bimodal fashion: 1) CdII induces around a two-orders-of-magnitude stabilization effect (log K 12 Zn II =20.8 vs. log K 12 Cd II =22.7), which defines an extremely high affinity of a peptide towards a metal ion, and 2) the displacement disrupts the overall assembly of the domain, as shown by NMR spectroscopic and anisotropy decay data. Based on the results, a new model explaining the molecular mechanism of CdII genotoxicity that underlines CdII 's impact on Rad50's dimer stability and quaternary structure that could potentially result in abrogation of the major DNA damage response pathway is proposed.

Electronic Structure of the Hieber Anion [Fe(CO)3(NO)]- Revisited by X-ray Emission and Absorption Spectroscopy.

While the Hieber anion [Fe(CO)3(NO)]- has been reincarnated in the last years as an active catalyst in organic synthesis, there is still a debate about the oxidation state of the central Fe atom and the resulting charge of the NO ligand. To shed new light on this question and to understand the Fe-NO interaction in the Hieber anion, it is investigated in comparison to the formal 3d8 reference Fe(CO)5 and the formal 3d10 reference [Fe(CO)4]2- by the combination of valence-to-core X-ray emission spectroscopy (VtC-XES), X-ray absorption near-edge structure spectroscopy (XANES), and high-energy-resolution fluorescence-detected XANES. In order to extract information about the electronic structure, time-dependent density functional theory and ground-state density functional theory calculations are applied. This combination of experimental and computational methods reveals that the electron density at the Fe center of the Hieber resembles that of the isoelectronic [Fe(CO)4]2-. These observations challenge recent descriptions of the Hieber anion and reopen the debate about the experimentally and computationally determined Fe oxidation state and charge on the NO ligand.

Surgical care in Poland after COVID-19 outbreak: a national survey.

B a c k g r o u n d: During COVID-19 pandemic, it is necessary to collect and analyze data concerning management of hospitals and wards to work out solutions for potential future crisis. The objective of the study was to investigate how surgical wards in Poland are managing during rapid development of the COVID-19 pandemic. M e t h o d s: An anonymous, online survey was designed and distributed to surgeons and surgery residents working in surgical departments during pandemic. Responders were divided into two groups: Group 1 (responders working in a "COVID-19-dedicated" hospital) and Group 2 (responders working in other hospitals). Results: Overall, 323 responders were included in the study group, 30.03% of which were female. Medical staff deficits were reported by 21.15% responders from Group 1 and 29.52% responders from Group 2 (p = 0.003). The mean number of elective surgeries performed weekly prior to the pandemic in Group 1 was 40.37 ± 46.31 and during the pandemic was 13.98 ± 37.49 (p < 0.001). In Group 2, the mean number of elective surgeries performed weekly before the start of the pandemic was 26.85 ± 23.52 and after the start of the pandemic, it was 7.65 ± 13.49 (p <0.001). There were significantly higher reported levels of preparedness in Group 1 in terms of: theoretical training of the staff, equipping the staff and adapting the operating theater to safely perform procedures on patients with COVID-19. Overall, 62.23% of responders presume being infected with SARS-CoV-2. C o n c l u s i o n s: SARS-CoV-2 pandemic had a significantly negative impact on surgical wards. Despite the preparations, the number of responders who presume being infected with SARS-CoV-2 during present crisis is high.

Perceptions of clinical teachers acting as examiners regarding the value of Objective Structured Clinical Examinations.

OBJECTIVES: OSCE (Objective Structured Clinical Examination) is a common method of assessing clinical skills used at many universities. An important and at the same time difficult aspect of good examination preparation is obtaining a properly trained and well-motivated group of assessors. To effectively recruit and maintain cooperation with assessors, it is worth to know their opinion. The aim of this study was to investigate the opinions of teacher-examiners about OSCE and to identify the factors that could shape this opinion and influence on motivation. METHODS: A cross-sectional study was conducted using a questionnaire on teachers who participated as OSCE examiners. This questionnaire consisted of 21 questions about their perceptions. Answers were rated in a five-point Likert-type scale. Chi-square or Fisher's exact test was used to analyze the data. RESULTS: A total of 49 (out of 52) teachers participated in this study. Nearly 90% of examiners believed that it is fair, more than 90% that it is transparent. Despite the fact that 67% of examiners believe the examination is difficult to organize and 71% believe it is stressful for students, according to 72% of respondents the OSCE has a positive effect on learning. More than 91% of examiners believed that the OSCE is an appropriate test to assess students' skills. Opinions about examination were independent of specialty, seniority, gender or taking the OSCE as students. CONCLUSION: Teacher-examiners viewed the OSCE as a fair and transparent examination, adequate for assessment of skills and, despite it being difficult to organize, worth doing as it is appropriate to assess practical skills and positively influences students' motivation to learn tested skills.

Shape adaptation of quinine in cyclodextrin cavities: NMR studies.

Complex formation between quinine and natural cyclodextrins (CD) was studied using NMR spectroscopy. The strongest association was observed for complexes of neutral quinine molecules with ßCD. Association constants for monocationic quinine were one order of magnitude smaller, while dicationic quinine did not bind to CDs. The distribution of complexation-induced shifts and ROESY spectra revealed bimodal quinine binding in complexes formed with ßCD and γCD. Complex formation resulted in a decrease of the vicinal coupling constant between H2 and H9 protons owing to the rotation about the C2-C9 bond and in consequence in mutual reorientation of two main constituents of quinine: quinoline and quinuclidine. DFT calculations allowed establishing that H2 and H9 protons are antiperiplanar in the prevailing quinine conformer(s) in aqueous solution. Conformers with synclinal H2 and H9 protons participated in quinine complexation with CDs.

Functional outcomes after resections for low rectal tumors: comparison of Transanal with laparoscopic Total Mesorectal excision.

BACKGROUND: Aim of this study was to evaluate functional outcomes of transanal total mesorectal excision (TaTME) in comparison to conventional laparoscopic approach (LaTME) in terms of low anterior resection syndrome (LARS). METHODS: Forty-six patients who underwent total mesorectal excision for low rectal cancer between 2013 and 2017 were enrolled. Primary outcome was the severity of faecal incontinence, assessed both before the treatment and 6 months after ileostomy reversal. LARS score and Jorge-Wexner scale were utilized to analyze its severity. RESULTS: Twenty (87%) from TaTME and 21 (91%) from LaTME group developed LARS postoperatively. There were no significant differences between groups in terms of LARS occurrence (p = 0.63) and severity. The median Wexner score was comparable in both groups (8 [IQR: 4-12] vs 7 [3-11], p = 0.83). Univariate analysis revealed that postoperative complications were a risk factor for LARS development (p = 0.02). Perioperative outcomes, including operative time, blood loss and intraoperative adverse events did not differ significantly between groups either. Five TaTME patients developed postoperative complications, while there were morbidity 6 cases in LaTME group. Quality of mesorectal excision was comparable with 20 and 19 complete cases in TaTME and LaTME groups, respectively. CONCLUSIONS: TaTME provided comparable outcomes in terms of functional outcomes in comparison to LaTME for total mesorectal excision in low rectal cancers. Having said that, LARS prevalence is still high and requires further evaluation of the technique.

The knowledge of Polish medical students about digital rectal examination.

BACKGROUND: The digital rectal examination (DRE) is a part of the standard physical examination and a useful diagnostic tool for detecting various lower gastrointestinal tract abnormalities. However nowadays it has been observed that medical students might not be properly prepared for performing and interpreting of DRE. The purpose of the study was to evaluate the knowledge and experience of Polish medical students about DRE. MATERIAL AND METHODS: A prospective study was carried out using a questionnaire accessible via internet platform. The survey consisted of 12 questions and considered experience as well as practical and theoretical knowledge about DRE. 976 responses from nine Polish medical universities were included in the study. RESULTS: 38.68% of students have never performed DRE with "lack of opportunity during courses" (71.09%) as the most common reason. Among responders who performed this examination only 12.72% had done it more than two times. Usefulness of DRE was mostly assessed as high and very high (55.63%). Students in the self-assessment part indicated low and very low (18.72% and 39.61%) technical abilities and also low (25.34%) interpretation skills. Conclusiosion: The knowledge of Polish medical students about DRE is insuffcient. Medical universities should pay particular attention to this field of examination to improve theoretical as well as practical skills of future doctors.