Students´ preparedness, learning habits and the greatest difficulties in studying Histology in the digital era: A comparison between students of general and dental schools.

INTRODUCTION: There are only sporadic references in literature regarding general medicine and dentistry student´s preparedness for Histology, study resources and how students might use them in the era of virtual microscopy. METHODS: A structured questionnaire was used to evaluate students´ opinion, with 192 students of general medicine and 82 students of dentistry responding. RESULTS: The dentistry students evaluate their previous knowledge of basic high school disciplines as less helpful when compared to their general medicine colleagues, but this difference diminishes during the first year of medical school studies. Students of dentistry display a better orientation in the amount of study resources (electronic vs printed) and also the ways of their use (practical vs theoretical preparation). The main problems surfacing in the study of Histology have been: the lack of time due to the high demands of Anatomy, problems with correct identification of structures in specimens and correct orientation in a large number of available study resources. Students indicate that they would appreciate the introduction of interactive exercise tests to verify practical and theoretical knowledge. CONCLUSION: We revealed significant differences between students of general medicine and dentistry in terms of student´s preparedness and learning habits. According to our findings, it is still necessary to further develop teaching methods utilising virtual microscopy, taking into account the needs of both general medicine and dental school students.

Evaluation of the effectiveness of the presentation of virtual histology slides by students during classes. Are there any differences in approach between dentistry and general medicine students?

INTRODUCTION: Virtual microscopy, used as a method to teach histology, has many undeniable advantages. However, the usefulness of this method is somewhat limited by the difficulties students face in finding their way through huge amounts of digital data, compounded by decreased interaction between students and teachers. We describe the results of a recent pilot project which combined the modern teaching methods of active learning, where students themselves present histological slides and make use of the virtual microscopy system. METHODS: Students' responses to a structured questionnaire and examination results were evaluated. RESULTS: We found that a combination of both electronic materials and textbooks was commonly used by students to prepare for practical teaching sessions, with electronic resources being used regularly by the majority of students. No statistically relevant differences were found between the approaches of dentistry vs general medicine students. Cooperation between students' groups during the preparation for individual presentations was seen to be beneficial by a majority of dentistry students; they reported that the introduction of student-led presentations improved their quality of preparation for practical lessons, as well as increasing their participation and activity level in the lessons themselves. These different approaches and motivations between students of dentistry and general medicine are reflected in the test results where dentistry students are more successful. CONCLUSION: We confirm that there are differences in motivation, approaches and examination results between both groups of students, which should be taken into account and which could lead to differentiation of future curricula for both study courses.

Time-dependent expression of cytochrome p450 epoxygenases during human prenatal development.

There is growing evidence that some members of cytochrome P450 enzymes contribute to regulation of normal prenatal development. CYP epoxygenases (CYP2C and CYP2J subfamilies) convert arachidonic acid into four regioisomeric epoxyeicosatrienoic acids (EETs), biologically active molecules involved in mitogenesis and cell signaling. Almost nothing is known about localization of their expression in tissues during human prenatal development. The spatio-temporal expression pattern of CYP2C8, CYP2C9, CYP2C19 and CYP2J2 in human embryonic/fetal intestines, liver, and kidney was investigated by immunohistochemical method. CYP epoxygenases are expressed already in early stages of development in these embryonic/fetal tissues (as early as 7th week of IUD in the intestines, 5th week of IUD in the liver, and 6th week of IUD in the kidney). In kidney, CYP epoxygenases are expressed in the metanephrogenic blastema (but not in the uninduced mesenchyme) and in the tubular system. In the intestines, diverse CYP epoxygenases distribution along crypt-villus axis could suggest role in cell differentiation. Moreover, we detected higher CYP2J2 level in these organs than in adult tissue samples.

Peroxisome proliferator-activated receptors in regulation of cytochromes P450: new way to overcome multidrug resistance?

Embryonic and tumour cells are able to protect themselves against various harmful compounds. In human pathology, this phenomenon exists in the form of multidrug resistance (MDR) that significantly deteriorates success of anticancer treatment. Cytochromes P450 (CYPs) play one of the key roles in the xenobiotic metabolism. CYP expression could contribute to resistance of cancer cells to chemotherapy. CYP epoxygenases (CYP2C and CYP2J) metabolize about 20% of clinically important drugs. Besides of drug metabolism, CYP epoxygenases and their metabolites play important role in embryos, normal body function, and tumors. They participate in angiogenesis, mitogenesis, and cell signaling. It was found that CYP epoxygenases are affected by peroxisome proliferator-activated receptor α (PPARα). Based on the results of current studies, we assume that PPARs ligands may regulate CYP2C and CYP2J and in some extent they may contribute to overcoming of MDR in patients with different types of tumours.

The detection of myc proteins in the developing human kidney.

The aim of our work was the detection of c- and N- myc proteins in the developing kidney of human fetuses especially in the neogenous zone. These proteins being localized in nucleus and encoded by the cellular oncogene myc function as transcriptional factors. Myc gene represents the key control gene in the course of cellular proliferation and differentiation. It also participates in the regulation of apoptosis and the origin of some cancers. Both proteins have been proved to be inevitable for proper nephrogenesis in mice. Considering the dearth of studies dealing with human embryonic tissues, we attempted to map the localization and spatiotemporal relations of the expression of these proteins during human nephrogenesis. In addition, issuing from our previous observations, we tried to compare their ways of expression with those of Bcl-2 (antiapoptotic effect) and Bax (proapoptotic function) proteins. Histologically normal kidneys were collected from eight human fetuses ranging from the 10th-30th week of IUD. Tissue samples were fixed in methacarn and processed by routine paraffin technique. Standard indirect three-step immunohistochemical method was applied for the detection of N- and c-myc proteins. In the neogenous zone both proteins are markedly present in metanephrogenic blastema with declining intensity with the increasing age of fetus. Branches of ureteral bud are almost negative. Such localization is also typical for Bcl-2 protein whereas Bax positive cells are present mostly in branches of the ureteral bud. It is not clear if all these proteins collaborate in the course of regulation of apoptosis in human metanephros.

The occurrence of c-myc, p53 and Bcl-2 family proteins in the early phase of development of duodenal epithelium.

In last few years, numerous groups of proteins participating in the regulation of cell proliferation, differentiation and death during ontogenesis have been described. In this study we compared the occurrence of Bcl-2, p53 and myc protein families with the level of proliferative activity and apoptosis during development of duodenal epithelium. Paraffin embedded tissues of eight human embryos and foetuses aged from the 6th-18th week of IUD were used. For the detection of apoptotic cells the TUNEL method was performed, the proliferative marker PCNA and all the proteins studied were detected by means of indirect three-step immunohistochemical method. In the 6th and 8th week of intrauterine development we observed isolated TUNEL positive epithelial cells only and this was accompanied by the disperse presence of PCNA as well as by all the studied proteins: Bcl-2, Bax, Bcl-XL, c-myc, N-myc, p53, p63 and p73. In the early foetal period of duodenal development we registered changes in PCNA and TUNEL positivity in accordance with the constitution of the stem cell pool on base of villi, where more numerous Bcl-2 positive cells were also found. The separation of primitive crypts and villi was not accompanied by any differences in distribution of Bax, Bcl-XL, c-myc, N-myc, p63 and p73 proteins between those compartments: all the studied proteins showed dispersed character. P53 rapidly decreased in this period. In the 18th week of intrauterine development the balance between proliferation in crypts and apoptosis of villi epithelium was well established and no p53 positive cells were found. In the presence of Bcl-2, Bax, Bcl-XL, p63 and p73 we did not find any dramatic changes. The myc proteins were restricted within the epithelium of the Lieberkuhn crypts only.

Degradation phase of apoptosis during the early stages of human metanephros development.

Apoptosis as a vital process is necessary for human intrauterine development. Not only the induction and course of apoptosis, but engulfment of the apoptotic cells (bodies) were the centre of our interest. Macrophages were detected in the early stages of human intrauterine development and the role of macrophages in the clearance of apoptotic cells in the early stages of human metanephros development was confirmed.

Part of CD68+ macrophages in the clearence of apoptotic bodies in human metanephros.

According to recent research on mice, less on human material, cells responsible for clearing apoptotic cells away during development are, besides non-professional phagocytes, also tissue-fixed macrophages. The aim of our work was the determination of macrophage role in the phagocytosis of apoptotic bodies in neogenous zone of human metanephros. Histologicaly normal kidneys were collected from embryos and fetuses ranging from the 8th-28th week of IUD. These tissues were routinely processed. In the first step we detected CD68+ cells by means of standard indirect three-step immunohistochemical method having used MAb NCL-CD68-KP1 (macrophage marker) to find out whether such cells are actually present. In the second step tissue sections were labelled by double-staining principle (TUNEL technique for the detection of apoptosis and above mentioned macrophage marker) to judge co-localization of these two items. The slides were observed by using immersion objective and the amount of apoptotic cells was expressed in percents. CD68+ macrophages appeared dispersely as single cells or small groups in all the ages studied. According to our results, CD68+ macrophages phagocytose 37-75% of apoptotic cells present in neogenous zone and the number of engulfed apoptotic cells increases in the 12th week of the IUD, i.e. in the early fetal period and later it merely fluctuates.