Quantifying teaching quality in medical education: The impact of learning gain calculation.

BACKGROUND: Student performance is a mirror of teaching quality. The pre-/post-test design allows a pragmatic approach to comparing the effects of interventions. However, the calculation of current knowledge gain scores introduces varying degrees of distortion. Here we present a new metric employing a linear weighting coefficient to reduce skewness on outcome interpretation. METHODS: We compared and contrasted a number of common scores (raw and relative gain scores) with our new method on two datasets, one simulated and the other empirical from a previous intervention study (n = 180) employing a pre-/post-test design. RESULTS: The outcomes of the common scores were clearly different, demonstrating a significant dependency on pre-test scores. Only the new metric revealed a linear relationship to the knowledge baseline, was less skewed on the upper or lower extremes, and proved well suited to allow the calculation of negative learning gains. Employing the empirical dataset, the new method also confirmed the interaction effect of teaching formats with specific subgroups of learner characteristics. CONCLUSION: This work introduces a new weighted metric enabling meaningful comparisons between interventions based on a linear transformation. This method will form the basis to intertwine the calculation of test performance closely with the outcome of learning as an important factor reflecting teaching quality and efficacy. Its regular use can improve the transparency of teaching activities and outcomes, contribute to forming rounded judgements of students' acquisition of knowledge and skills and enable valuable feedforward to develop and enhance curricular concepts.

Influence of Short and Long Hyperglycemia on Cardioprotection by Remote Ischemic Preconditioning-A Translational Approach.

The adverse impact of common diseases like diabetes mellitus and acute hyperglycemia on morbidity and mortality from myocardial infarction (MI) has been well documented over the past years of research. In the clinical setting, the relationship between blood glucose and mortality appears linear, with amplifying risk associated with increasing blood glucose levels. Further, this seems to be independent of a diagnosis of diabetes. In the experimental setting, various comorbidities seem to impact ischemic and pharmacological conditioning strategies, protecting the heart against ischemia and reperfusion injury. In this translational experimental approach from bedside to bench, we set out to determine whether acute and/or prolonged hyperglycemia have an influence on the protective effect of transferred human RIPC-plasma and, therefore, might obstruct translation into the clinical setting. Control and RIPC plasma of young healthy men were transferred to isolated hearts of young male Wistar rats in vitro. Plasma was administered before global ischemia under either short hyperglycemic (HGs Con, HGs RIPC) conditions, prolonged hyperglycemia (HGl Con, HGl RIPC), or under normoglycemia (Con, RIPC). Infarct sizes were determined by TTC staining. Control hearts showed an infarct size of 55 ± 7%. Preconditioning with transferred RIPC plasma under normoglycemia significantly reduced infarct size to 25 ± 4% (p < 0.05 vs. Con). Under acute hyperglycemia, control hearts showed an infarct size of 63 ± 5%. Applying RIPC plasma under short hyperglycemic conditions led to a significant infarct size reduction of 41 ± 4% (p < 0.05 vs. HGs Con). However, the cardioprotective effect of RIPC plasma under normoglycemia was significantly stronger compared with acute hyperglycemic conditions (RIPC vs. HGs RIPC; p < 0.05). Prolonged hyperglycemia (HGl RIPC) completely abolished the cardioprotective effect of RIPC plasma (infarct size 60 ± 7%; p < 0.05 vs. HGl Con; HGl Con 59 ± 5%).

The adaptation of colorectal cancer cells when forming metastases in the liver: expression of associated genes and pathways in a mouse model.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer-related death in men and women. Systemic disease with metastatic spread to distant sites such as the liver reduces the survival rate considerably. The aim of this study was to investigate the changes in gene expression that occur on invasion and expansion of CRC cells when forming metastases in the liver. METHODS: The livers of syngeneic C57BL/6NCrl mice were inoculated with 1 million CRC cells (CMT-93) via the portal vein, leading to the stable formation of metastases within 4 weeks. RNA sequencing performed on the Illumina platform was employed to evaluate the expression profiles of more than 14,000 genes, utilizing the RNA of the cell line cells and liver metastases as well as from corresponding tumour-free liver. RESULTS: A total of 3329 differentially expressed genes (DEGs) were identified when cultured CMT-93 cells propagated as metastases in the liver. Hierarchical clustering on heat maps demonstrated the clear changes in gene expression of CMT-93 cells on propagation in the liver. Gene ontology analysis determined inflammation, angiogenesis, and signal transduction as the top three relevant biological processes involved. Using a selection list, matrix metallopeptidases 2, 7, and 9, wnt inhibitory factor, and chemokine receptor 4 were the top five significantly dysregulated genes. CONCLUSION: Bioinformatics assists in elucidating the factors and processes involved in CRC liver metastasis. Our results support the notion of an invasion-metastasis cascade involving CRC cells forming metastases on successful invasion and expansion within the liver. Furthermore, we identified a gene expression signature correlating strongly with invasiveness and migration. Our findings may guide future research on novel therapeutic targets in the treatment of CRC liver metastasis.

Examiner effect on the objective structured clinical exam - a study at five medical schools.

BACKGROUND: The Objective Structured Clinical Examination (OSCE) is increasingly used at medical schools to assess practical competencies. To compare the outcomes of students at different medical schools, we introduced standardized OSCE stations with identical checklists. METHODS: We investigated examiner bias at standardized OSCE stations for knee- and shoulder-joint examinations, which were implemented into the surgical OSCE at five different medical schools. The checklists for the assessment consisted of part A for knowledge and performance of the skill and part B for communication and interaction with the patient. At each medical faculty, one reference examiner also scored independently to the local examiner. The scores from both examiners were compared and analysed for inter-rater reliability and correlation with the level of clinical experience. Possible gender bias was also evaluated. RESULTS: In part A of the checklist, local examiners graded students higher compared to the reference examiner; in part B of the checklist, there was no trend to the findings. The inter-rater reliability was weak, and the scoring correlated only weakly with the examiner's level of experience. Female examiners rated generally higher, but male examiners scored significantly higher if the examinee was female. CONCLUSIONS: These findings of examiner effects, even in standardized situations, may influence outcome even when students perform equally well. Examiners need to be made aware of these biases prior to examining.

The anthelmintic niclosamide inhibits colorectal cancer cell lines via modulation of the canonical and noncanonical Wnt signaling pathway.

BACKGROUND: Wnt/ß-catenin signaling is known to play an important role in colorectal cancer (CRC). Niclosamide, a salicylamide derivative used in the treatment of tapeworm infections, targets the Wnt/ß-catenin pathway. The objective of this study was to investigate niclosamide as a therapeutic agent against CRC. METHODS: The antiproliferative effects of 1, 3, 10, and 50 µM concentrations of niclosamide on human (SW480 and SW620) and rodent (CC531) CRC cell lines were determined by MTS assay and direct cell count. The lymphoid enhancer-binding factor 1/transcription factor (LEF/TCF) reporter assay monitored the activity of Wnt signaling. Immunofluorescence staining demonstrated the expression pattern of active ß-catenin. Gene expression of canonical and noncanonical Wnt signaling components was analyzed using qRT-PCR. Western blot analysis was performed with antibodies detecting nuclear localization of ß-catenin and c-jun. RESULTS: Cell proliferation in CRC cell lines was blocked dose dependently after 12 and 24 h of incubation. The Wnt promoter activity of LEF/TCF significantly decreased with niclosamide concentrations of 10 and 50 µM after 12 h of incubation. Active ß-catenin did not shift from the nuclear to the cytosolic pool. However, canonical target genes (met, MMP7, and cyclin D1) as well as the coactivating factor Bcl9 were downregulated, whereas the noncanonical key player c-jun was clearly activated. CONCLUSIONS: Niclosamide treatment is associated with an inhibitory effect on CRC development and reduced Wnt activity. It may exert its effect by interfering with the nuclear ß-catenin-Bcl9-LEF/TCF triple-complex and by upregulation of c-jun representing noncanonical Wnt/JNK signaling. Thus, our findings warrant further research into this substance as a treatment option for patients with advanced CRC.

Biographic Characteristics and Factors Perceived as Affecting Female and Male Careers in Academic Surgery: The Tenured Gender Battle to Make It to the Top.

PURPOSE: Given the high attrition rate in the field of academic surgery, we aimed to characterise the professional and personal situations of female and male academic surgeons as well as to gather data on their respective perceptions of career advancement and work satisfaction. METHODS: We conducted a cross-sectional survey in Germany, inviting all identifiable academically highly qualified female surgeons and their male counterparts in a 1:2 ratio to participate. An anonymous 103-item online questionnaire was designed and the data collected between July and September 2014. RESULTS: The questionnaire was sent to 93 female and 200 male surgeons, of whom 63 women (67.7%) and 70 men (35.0%) replied. The average age was 47.5 and 47.1 years, respectively. Respondents identified 'high degree of expertise', 'ambition', and 'clarity of one's professional aims' as important factors affecting professional career development. Both groups felt 'workload', 'working hours/shifts', and 'gender' to be a hindrance, the latter of significantly greater importance to female surgeons. The mean work satisfaction scores were high in both female (69.5%) and male (75.7%) surgeons. The predictors 'support from superiors' (standardised ß coefficient = 0.41) and 'manual aptitude' (ß = 0.41) contributed incrementally to the variance in 'high degree of work satisfaction' (90-100%) observed for female surgeons. However, childcare provided by 'kindergarten/crèche/after-school care' had the greatest negative predictive value (ß = -1.33). CONCLUSIONS: Although there are many parallels, female faculty members experience the culture of academic surgery to some extent differently from their male counterparts, especially when impacted by parenthood and childcare. Faculty development programmes need to develop strategies to improve perceived equality in career opportunities by respecting individuals' requirements as well as offering gender-appropriate career guidance.

Standardized and quality-assured video-recorded examination in undergraduate education: informed consent prior to surgery.

BACKGROUND: Communication skills combined with specialized knowledge are fundamental to the doctor-patient relationship in surgery. During a single-station video-recorded objective structured clinical examination (VOSCE), students were tasked with obtaining informed consent. Our aim was to develop a standardized and quality-assured assessment method in undergraduate education. METHODS: One hundred fifty-five students in their fifth year of medical school (78 videos) participated in a summative VOSCE within the framework of the teaching module "Operative Medicine." They prepared for three clinical scenarios and the surgical procedures involved. The examination comprised participants having to obtain informed consent from simulated patients, video recording their performance. Students were assessed by two independent raters, the background of one of whom was nonsurgical. Results were statistically tested using SPSS. RESULTS: Students' scores were all beyond the pass mark of 70%, averaging 91.0% (±4.0%), 88.4% (±4.4%), and 87.0% (±4.7%) for the appendectomy, cholecystectomy, and inguinal hernia repair checklist, respectively. Most items (68%-89% of the checklists) were found to have fair to excellent discrimination values. Cronbach's α values ranged between 0.565 and 0.605 for the individual checklists. Interrater agreement was strong (Pearson correlation coefficient = 0.80, P < 0.01; intraclass correlation coefficient 2.1 = 0.78). CONCLUSIONS: The VOSCE is both feasible and reliable as a method of assessing student communication skills and the application of clinical knowledge while obtaining informed consent in surgery. This method is efficient (flexible rating outside normal working hours possible with reductions in administrative load) and may be used for high-stakes evaluation of student performance.

A TRPC3 blocker, ethyl-1-(4-(2,3,3-trichloroacrylamide)phenyl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate (Pyr3), prevents stent-induced arterial remodeling.

TRPC-mediated Ca(2+) entry has been implicated in the control of smooth muscle proliferation and might represent a pivotal mechanism underlying in-stent restenosis. As we have observed significant expression of TRPC3 in human smooth muscle from the coronary artery as well as the aorta, we tested the efficiency of a recently discovered TRPC3 selective Ca(2+) entry blocker Pyr3 to prevent vascular smooth muscle proliferation and stent implantation-induced hyperplasia of human aorta. The effect of Pyr3 on proliferation was measured by detection of BrdU incorporation and PCNA expression in human coronary smooth muscle and microvascular endothelium, which displays significantly smaller expression levels of TRPC3 as compared with smooth muscle. Pyr3 inhibited smooth muscle proliferation but lacked detectable effects on endothelial proliferation. Measurements of ATP-induced Ca(2+) signals revealed that Pyr3 suppressed agonist-induced Ca(2+) entry more effectively in vascular smooth muscle than in endothelial cells. Inhibitory effects of Pyr3 on stent implantation-induced arterial injury was tested using a novel in vitro model of in-stent hyperplasia in human arteries based on organ typical culture of human aortic constructs. Pyr3 effectively prevented increases in tissue levels of PCNA and Ki-67 at 2 weeks after stent implantation into human aortae. Similarly, proliferation markers were significantly suppressed when implanting a Pyr3-releasing stent prototype as compared with a bare metal stent (BMS) control. Our results suggest TRPC3 as a potential target for pharmacological control of smooth muscle proliferation. Selectively inhibition of TRPC Ca(2+) entry channels in vascular smooth muscle is suggested as a promising strategy for in-stent restenosis prevention.

A novel approach to microsurgical teaching in head and neck surgery leveraging modern 3D technologies.

The anatomically complex and often spatially restricted conditions of anastomosis in the head and neck region cannot be adequately reproduced by training exercises on current ex vivo or small animal models. With the development of a Realistic Anatomical Condition Experience (RACE) model, complex spatial-anatomical surgical areas and the associated intraoperative complexities could be transferred into a realistic training situation in head and neck surgery. The RACE model is based on a stereolithography file generated by intraoperative use of a three-dimensional surface scanner after neck dissection and before microvascular anastomosis. Modelling of the acquired STL file using three-dimensional processing software led to the model's final design. As a result, we have successfully created an economical, sustainable and realistic model for microsurgical education and provide a step-by-step workflow that can be used in surgical and general medical education to replicate and establish comparable models. We provide an open source stereolithography file of the head-and-neck RACE model for printing for educational purposes. Once implemented in other fields of surgery and general medicine, RACE models could mark a shift in medical education as a whole, away from traditional teaching principles and towards the use of realistic and individualised simulators.

The growth pattern of transplanted normal and nodular hepatocytes.

Overt neoplasia is often the end result of a long biological process beginning with the appearance of focal lesions of altered tissue morphology. While the putative clonal nature of focal lesions has often been emphasized, increasing attention is being devoted to the possible role of an altered growth pattern in the evolution of carcinogenesis. Here we compare the growth patterns of normal and nodular hepatocytes in a transplantation system that allows their selective clonal proliferation in vivo. Rats were pre-treated with retrorsine, which blocks the growth of resident hepatocytes, and were then transplanted with hepatocytes isolated from either normal liver or hepatocyte nodules. Both cell types were able to proliferate extensively in the recipient liver, as expected. However, their growth pattern was remarkably different. Clusters of normal hepatocytes integrated in the host liver, displaying a normal histology; however, transplanted nodular hepatocytes formed new hepatocyte nodules, with altered morphology and sharp demarcation from surrounding host liver. Both the expression and distribution of proteins involved in cell polarity, cell communication, and cell adhesion, including connexin 32, E-cadherin, and matrix metalloproteinase-2, were altered in clusters of nodular hepatocytes. Furthermore, we were able to show that down-regulation of connexin 32 and E-cadherin in nodular hepatocyte clusters was independent of growth rate. These results support the concept that a dominant pathway towards neoplastic disease in several organs involves defect(s) in tissue pattern formation.

The plasminogen activator inhibitor system in colon cancer cell lines is influenced by the CO2 pneumoperitoneum.

PURPOSE: Laparoscopic surgery in the treatment of colon carcinoma causes pH value alterations as well as changes in fibrinolytic activity. This results in enhanced proliferation of colon carcinoma cells in vitro and also in enhanced growth of liver metastasis when compared to isobaric (gasless) laparoscopy in vivo. So far, the direct influence of CO(2) pneumoperitoneum on the invasiveness and metastatic capabilities of colon cancer cells remains unclear. We therefore evaluated transcripts of the uPA system. METHODS: The influence of CO(2) pneumoperitoneum on the gene expression of plasminogen activator inhibitor-1 (PAI-1), urokinase-type plasminogen activator (uPA), and tissue-type plasminogen activator (tPA) was investigated in colon carcinoma cell lines (HT116, SW48, and WiDr) and mesothelial cells employing a pneumoperitoneum chamber in vitro. Quantitative gene expression data were collected using real-time RT-PCR and statistical analysis was performed by means of analysis of variance and Bonferroni correction. RESULTS: The expression of uPA and PAI-1 was increased in colon carcinoma cell lines when cultivated at pH 6.1, a value corresponding to intraabdominal pH values during CO(2) insufflation. Elevated PAI-1 mRNA levels were also observed when CO(2) was simultaneously applied with a pressure of 10 mmHg. In contrast, there were no significant changes in mesothelial cells in the investigated parameter. CONCLUSION: The conditions of CO(2) pneumoperitoneum cause changes in the expression of genes controlling the fibrinolytic activity. The increase of PAI-1 and uPA can contribute to the enhancement of metastasis and invasive potential of tumour cells. Therefore, changes in the conditions of laparoscopy may well optimise laparoscopic therapy in colon cancer.

Psychometric Properties and Calibration of the SPOREEM (Students' Perception of the Operating Room Educational Environment Measure).

OBJECTIVE: The experience in the operating room is considered as a crucial element affecting medical students' satisfaction with workplace-based training in surgery. We developed the "Students' Perception of the Operating Room Educational Environment Measure" (SPOREEM) and applied the approach of Item Response Theory to improve accuracy of its measurement. DESIGN: Psychometric analysis determined the factorial structure. Using Item Response Theory, item thresholds were calculated on response option levels. Sum scores in the factors were then computed using calibrated unit weights. SETTING: One hundred medical students from the University Medical Center in Goettingen, Germany, enrolled in a one-week surgery rotation completed the SPOREEM. RESULTS: The final 19-item questionnaire resulted in 3 factors: "Learning support and inclusion" (1), "Workplace atmosphere" (2), and "Experience of emotional stress" (3). Item calibration resulted in refinement of sum scores in the factors. Male students significantly rated factor 1 more positively. Factor 2 was perceived to a similar degree in all 3 surgical disciplines involved. Factor 3 was rated lower by those students planning a surgical field of postgraduate training. CONCLUSIONS: We developed a valid, reliable, and feasible tool to assess the overall educational climate of undergraduate training in the OR. Calibration of items refined the measurement.

Speaking up behavior and cognitive bias in hand hygiene: Competences of German-speaking medical students.

INTRODUCTION: Infection prevention and speaking up on errors are core qualities of health care providers. Heuristic effects (e.g. overconfidence) may impair behavior in daily routine, while speaking up can be inhibited by hierarchical barriers and medical team factors. Aim of this investigation was to determine, how medical students experience these difficulties for hand hygiene in daily routine. METHODS: On the base of prior investigations we developed a questionnaire with 5-point Likert ordinal scaled items and free text entries. This was tested for validity and reliability (Cronbach's Alpha 0.89). Accredited German, Swiss and Austrian universities were contacted and medical students asked to participated in the anonymous online survey. Quantitative statistics used parametric and non-parametric tests and effect size calculations according to Lakens. Qualitative data was coded according to Janesick. RESULTS: 1042 undergraduates of 12 universities participated. All rated their capabilities in hand hygiene and feedback reception higher than those of fellow students, nurses and physicians (p<0.001). Half of the participants rating themselves to be best educated, realized that faulty hand hygiene can be of lethal effect. Findings were independent from age, sex, academic course and university. Speaking-up in case of omitted hand hygiene was rated to be done seldomly and most rare on persons of higher hierarchic levels. Qualitative results of 164 entries showed four main themes: 1) Education methods in hand hygiene are insufficient, 2) Hierarchy barriers impair constructive work place culture 3) Hygiene and feedback are linked to medical ethics and 4) There is no consequence for breaking hygiene rules. DISCUSSION: Although partially limited by the selection bias, this study confirms the overconfidence-effects demonstrated in post-graduates in other settings and different professions. The independence from study progress suggests, that the effect occurs before start of the academic course with need for educational intervention at the very beginning. Qualitative data showed that used methods are insufficient and contradictory work place behavior in hospitals are frustrating. Even 20 years after "To err is human", work place culture still is far away from the desirable.

Surgeons' participation in the development of collaboration and management competencies in undergraduate medical education.

The teaching of professional roles in medical education is an interdisciplinary concern. However, surgeons require specific standards of professionalism for certain context-based situations. In addition to communication, studies require collaboration, leadership, error-/conflict-management, patient-safety and decision-making as essential competencies for surgeons. Standards for corresponding competencies are defined in special chapters of the German National Competency-based Learning Objectives for Undergraduate Medical Education (NKLM; chapter 8, 10). The current study asks whether these chapters are adequately taught in surgical curricula. Eight German faculties contributed to analysing mapping data considering surgical courses of undergraduate programs. All faculties used the MERlin mapping platform and agreed on procedures for data collection and processing. Sub-competency and objective coverage, as well as the achievement of the competency level were mapped. Overall counts of explicit citations were used for analysis. Collaboration within the medical team is a strongly represented topic. In contrast, interprofessional cooperation, particularly in healthcare sector issues is less represented. Patient safety and dealing with errors and complications is most emphasized for the Manager/Leader, while time management, career planning and leadership are not addressed. Overall, the involvement of surgery in teaching the competencies of the Collaborator and Manager/Leader is currently low. However, there are indications of a curricular development towards explicit teaching of these roles in surgery. Moreover, implicitly taught roles are numerous, which indicates a beginning awareness of professional roles.

Noninvasive imaging of liver repopulation following hepatocyte transplantation.

Near infrared fluorescence (NIRF) optical imaging is a technique particularly powerful when studying in vivo processes at the molecular level in preclinical animal models. We recently demonstrated liver irradiation under the additional stimulus of partial hepatectomy as being an effective primer in the rat liver repopulation model based on hepatocyte transplantation. The purpose of this study was to assess optical imaging and the feasibility of donor cell expansion tracking in vivo using a fluorescent probe. Livers of dipeptidylpeptidase IV (DPPIV)-deficient rats were preconditioned with irradiation. Four days later, a partial hepatectomy was performed and wild-type (DPPIV+) hepatocytes were transplanted into recipient livers via the spleen. Repopulation by transplanted DPPIV+ hepatocytes was detected in vivo with Cy5.5-conjugated DPPIV antibody using the eXplore Optix System (GE HealthCare). Results were compared with nontransplanted control animals and transplanted animals receiving nonspecific antibody. Optical imaging detected Cy5.5-specific fluorescence in the liver region of the transplanted animals, increasing in intensity with time, representing extensive host liver repopulation within 16 weeks following transplantation. A general pattern of donor cell multiplication emerged, with an initially accelerating growth curve and later plateau phase. In contrast, no specific fluorescence was detected in the control groups. Comparison with ex vivo immunofluorescence staining of liver sections confirmed the optical imaging results. Optical imaging constitutes a potent method of assessing the longitudinal kinetics of liver repopulation in the rat transplantation model. Our results provide a basis for the future development of clinical protocols for suitable fluorescent dyes and imaging technologies.

Digital Affinity in Medical Students Influences Learning Outcome: A Cluster Analytical Design Comparing Vodcast With Traditional Lecture.

BACKGROUND/OBJECTIVE: Undergraduate medical education still relies on lectures as the core teaching activity. However, e-learning and new media have begun to augment learning and information gathering over the last few years. The aim of this study was to investigate the effect of 2 teaching formats in surgical education, a classic lecture and a video podcast (vodcast), on knowledge gain, in particular with respect to the participants' characteristics and preferences. DESIGN: A prospective study was conducted over 2 consecutive semesters. A traditional lecture on goitre was given to the first of the 2 semesters and replaced by a matching vodcast made available to the second. An untaught subject (cholelithiasis) served as control. Knowledge gain was calculated as the difference in point scores between entry and mid-module examinations. Furthermore, participants completed a postintervention survey, in which they specifically rated their digital affinity and learning preferences. A cluster analysis was conducted pooling both semesters to evaluate differences between individuals affecting their performance. RESULTS: Both teaching formats resulted in a significant knowledge gain. Two clusters could be identified across both semesters: Cluster 2 (Digital natives) proved to be significantly different from Cluster 1 (Traditional) with respect to the 4 variables: "technically interested," the "use of smartphones," "activity in social networks," and "reading in digital formats." The knowledge gain differences between formats for students in the "Traditional" cluster were statistically insignificant. However, students in the cluster "Digital natives" performed significantly worse when exposed to the lecture format. CONCLUSIONS: Cluster analysis revealed that the students with an obvious affinity to information communication technology were found to be at a significant disadvantage in the lecture. In future, we recommend offering some form of pretest to determine an individual's profile and empower students to plan their learning activities accordingly.

Irradiation as preparative regimen for hepatocyte transplantation causes prolonged cell cycle block.

PURPOSE: Hepatocyte transplantation following liver irradiation (IR) and partial hepatectomy (PH) leads to extensive liver repopulation. We investigated the changes in the liver induced by IR explaining the loss of reproductive integrity in endogenous hepatocytes. MATERIALS AND METHODS: Right lobules of rat liver underwent external beam IR (25 Gy). A second group was subjected to additional 33% PH of the untreated left liver lobule. Liver specimens and controls were analyzed for DNA damage, apoptosis, proliferation and cell cycle related genes (1 hour to up to 12 weeks). RESULTS: Double strand breaks (phosphorylated histone H2AX) induced by IR rapidly declined within hours and were no longer detectable after 4 days. No significant apoptosis was noted and steady mRNA levels (B-cell lymphoma 2-associated X protein (BAX), caspase 3 and 9) were in line with the lack of DNA fragmentation. However, gene expression of p53 and p21 in irradiated liver tissue increased. Transcripts of cyclin D1, proliferating cell nuclear antigen (PCNA), and cyclin B augmented progressively, whereas cyclin E was only affected moderately. Following PH, irradiated livers displayed persistently high protein levels of p21 and cyclin D1. However, cell divisions were infrequent, as reflected by low PCNA levels up to four weeks. CONCLUSION: IR leads to a major arrest in the G(1)/S phase and to a lesser extent in the G(2)/M transition of the cell cycle, resulting in reduced regenerative response following PH. The persistent block of at least four weeks may promote preferential proliferation of transplanted hepatocytes in this milieu.

Does quantity ensure quality? Standardized OSCE-stations for outcome-oriented evaluation of practical skills at different medical faculties.

BACKGROUND: Practical skills are often assessed using Objective Structured Clinical Skill Exams (OSCE). Nevertheless, in Germany, interchange and agreement between different medical faculties or a general agreement on the minimum standard for passing is lacking. METHODS: We developed standardized OSCE-stations for assessing structured clinical examination of knee and shoulder joint with identical checklists and evaluation standards. These were implemented into the OSCE-course at five different medical faculties. Learning objectives for passing the stations were agreed beforehand. At each faculty, one reference examiner scored independently of the local examiner. Outcome of the students at the standardized station was compared between faculties and correlated to their total outcome at the OSCE, to their results at the Part One of the National Medical Licensing Examination as a reference test during medical studies and to their previous amount of lessons in examining joints. RESULTS: Comparing the results of the reference examiner, outcome at the station differed significantly between some of the participating medical faculties. Depending on the faculty, mean total results at the knee-examination-station differed from 64.4% to 77.9% and at the shoulder-examination-station from 62.6% to 79.2%. Differences were seen in knowledge-based items and also in competencies like communication and professional manner. There was a weak correlation between outcome at the joint-examination-OSCE-station and Part One of the National Medical Licensing Examination, and a modest correlation between outcome at the joint-examination-station and total OSCE-result. Correlation to the previous amount of lessons in examining joint was also weak. CONCLUSION: Although addressing approved learning objectives, different outcomes were achieved when testing a clinical skill at different medical faculties with a standardized OSCE-station. Results can be used as a tool for evaluating lessons, training and curricula at the different sites. Nevertheless, this study shows the importance of information exchange and agreement upon certain benchmarks and evaluation standards when assessing practical skills.

External-beam radiotherapy as preparative regimen for hepatocyte transplantation after partial hepatectomy.

PURPOSE: The transplantation of donor hepatocytes is considered a promising option to correct chronic liver failure through repopulation of the diseased organ. This study describes a novel selective external-beam irradiation technique as a preparative regimen for hepatocyte transplantation. METHODS AND MATERIALS: Livers of dipeptidylpeptidase IV (DPPIV)-deficient rats were preconditioned with external-beam single-dose irradiation (25 Gy) delivered to two thirds of the liver. Four days later, a one-third partial hepatectomy (PH) was performed to resect the untreated liver section, and 15 million wild-type (DPPIV+) hepatocytes were transplanted via the spleen into the recipient livers. The degree of donor-cell integration and growth was studied 8 h, 3 days, and 5 and 12 weeks after transplantation. RESULTS: Transplanted hepatocytes integrated rapidly into the irradiated liver and proliferated as clusters, finally repopulating the host liver to approximately 20% hepatocyte mass. After 12 weeks, donor cells and their numerous descendents were fully integrated and expressed functional markers to the same extent as host hepatocytes. CONCLUSIONS: We demonstrate that external-beam liver irradiation is sufficient to achieve partial repopulation of the host liver after hepatocyte transplantation, under the additional stimulus of one-third PH. The method described has potentially good prospects for its application in a clinically viable form of treatment.

Liver repopulation after hepatocellular transplantation: integration and interaction of transplanted hepatocytes in the host.

The mechanisms of donor hepatocyte integration into recipient liver are not fully understood. We investigated mechanisms of both the integration and interaction of transplanted hepatocytes with host liver cells as well as the repopulation of the host organ following intraportal transplantation. Mature hepatocytes were injected into the portal vein of dipeptidylpeptidase IV (DPPIV)-deficient rats pretreated with retrorsine and subjected to 30% partial hepatectomy to ensure selective donor growth. The degree of integration and proliferation was studied by colocalizing transplanted cells (DPPIV positive) with connexin 32, MMP-2, and OX-43 (multilayer immunofluorescence imaging). FACS analysis was established to assess the extent of repopulation quantitatively. Transplanted hepatocytes reached the distal portal spaces and sinusoids within 1 h after injection. A small proportion of cells succeeded in traversing the endothelial barrier through mechanical disruption in both locations. Transplanted hepatocytes lost their membrane-bound gap junctions (connexin 32) during this process. Successful integration of the donor cells required up to 5 days, heralded by gap junction reconstitution and the specific basolateral membrane expression of DPPIV. MMP-2 degraded the extracellular matrix in close proximity to donor cells, providing space for cell division. FACS analysis revealed that more than 37% of the liver was repopulated by cells derived from donors at 2 months after transplantation. Our data demonstrate a high degree of donor cell repopulation of the host organ and provide valuable insight into the specific mechanisms of donor cell integration. Connexin 32 expression in transplanted hepatocytes may serve as an indicator of their effective incorporation and communication within the recipient liver. FACS analysis reveals an accurate method to determine quantitatively the extent of liver repopulation.