Analysis of a nurse-provided on-call peritoneal dialysis support in an outpatient reference care centre.

BACKGROUND: To analyse the nature of medical or technical emergency issues of ambulatory peritoneal dialysis (PD) patients calling a nurse-provided emergency PD support service of a reference centre that is provided all year in the after-hours. METHODS: We retrospectively analysed patients' chief complaint, urgency, resolution of and association to current PD treatment and modality directed to an on-call nurse-provided PD support service from 2015-2021 based on routinely collected health data. Calls were systematically categorized being technical/procedural-, medical-, material-related or type of correspondence. Call urgency was categorized to have "immediate consequence", inquiry was eligible for "processing next working day" or whether there was "no need for further action". Call outcomes were classified according to whether patients were able to initiate, resume or finalize their treatments or whether additional interventions were required. Unexpected adverse events such as patients' acute hospitalization or need for nurses' home visits were evaluated and quantified. RESULTS: In total 753 calls were documented. Most calls were made around 7:30 a.m. (5:00-9:00; median, 25-75th CI) and 6:30 p.m. (5:00-8:15). 645 calls were assigned to continuous ambulatory- (CAPD) or automated PD (APD). Of those, 430 calls (66.7%) had an "immediate consequence". Of those 77% (N = 331) were technical/procedural-, 12.8% (N = 55) medical- and 6.3% (N = 27) material related issues. 4% (N = 17) were categorized as other correspondence. Issues disrupting the course of PD were identified in 413 cases. In 77.5% (N = 320) patients were able to initiate, resume or finalize their treatment after phone consultation. Last-bag exchange was used in 6.1% enabling continued therapy in 83.6%. In 35 cases a nurse visit at patients' home or patients' visit to the practice at the earliest possible date were required, while hospitalization was required in seven medical category cases (5.4% and 1.09% of total assessed calls, respectively). CONCLUSION: The on-call PD-nurse provides patient support for acute and imminent issues enabling them to successfully initiate, resume or finalize their prescribed treatment. Nurses triage of acute conditions facilitated rapid diagnostics and therapy. Maintaining quality PD homecare, the provision of trained personnel is indispensable. The information gathered in this study may therefore be used as a foundation to tailor educational programs for nephrology nurses and doctors to further develop their competencies in PD.

Medical education during the Covid-19 pandemic long-term experiences of German clinical medical students.

INTRODUCTION: Due to the Covid-19 pandemic and the accompanying hygiene regulations, medical students in Germany faced multiple educational and personal challenges. The challenges included the cancellation and digitalisation of courses, the closing of university institutions such as libraries, a decrease in social contacts, and the risk of a Covid-19 infection. The aim of this study was to understand medical students' pandemic experiences as well as the consequences of these experiences for the students' future work as physicians. MATERIALS AND METHODS: We performed 15 guided, one-on-one interviews with clinical medical students (third to fifth year) at the Otto-von-Guericke-University Magdeburg. Interviews were recorded, transcribed, and anonymised. We performed a qualitative content analysis in accordance with Mayring and thereby formed an inductive category system. The Consolidated Criteria for Reporting Qualitative Research (COREQ) were applied. RESULTS: Five categories were inductively formed: "Changes in the teaching experience", "negative effects on the learning experience", "decrease in personal social contacts", "contact with covid-19", and "pandemic-associated stress increase". The participating students reported higher levels of stress due to isolation and uncertainty regarding their educational future. Furthermore, students welcomed the digitalisation of lectures, developed individual coping strategies, and voluntarily took part in the care of Covid-19 patients. Limitations to social interactions were perceived as the major restrictive factor to their educational structure, their perceived learning success and personal development. CONCLUSION: This study identified social restrictions as well as didactic and academic structural challenges as relevant factors contributing to perceived stress and fear for medical students during the Covid-19 pandemic, especially as regards their learning experience. Students' acceptance of digitalised learning may enable regular interaction with university peers and may facilitate a structured educational life. However, the implementation of digital resources could not provide a sufficient substitute for in-person courses.

Neutrophil Gelatinase-Associated Lipocalin Cutoff Value Selection and Acute Kidney Injury Classification System Determine Phenotype Allocation and Associated Outcomes.

Background: We explored the extent to which neutrophil gelatinase-associated lipocalin (NGAL) cutoff value selection and the acute kidney injury (AKI) classification system determine clinical AKI-phenotype allocation and associated outcomes. Methods: Cutoff values from ROC curves of data from two independent prospective cardiac surgery study cohorts (Magdeburg and Berlin, Germany) were used to predict Kidney Disease: Improving Global Outcome (KDIGO)- or Risk, Injury, Failure, Loss of kidney function, End-stage (RIFLE)-defined AKI. Statistical methodologies (maximum Youden index, lowest distance to [0, 1] in ROC space, sensitivity≍specificity) and cutoff values from two NGAL meta-analyses were evaluated. Associated risks of adverse outcomes (acute dialysis initiation and in-hospital mortality) were compared. Results: NGAL cutoff concentrations calculated from ROC curves to predict AKI varied according to the statistical methodology and AKI classification system (10.6-159.1 and 16.85-149.3 ng/mL in the Magdeburg and Berlin cohorts, respectively). Proportions of attributed subclinical AKI ranged 2%-33.0% and 10.1%-33.1% in the Magdeburg and Berlin cohorts, respectively. The difference in calculated risk for adverse outcomes (fraction of odds ratios for AKI-phenotype group differences) varied considerably when changing the cutoff concentration within the RIFLE or KDIGO classification (up to 18.33- and 16.11-times risk difference, respectively) and was even greater when comparing cutoff methodologies between RIFLE and KDIGO classifications (up to 25.7-times risk difference). Conclusions: NGAL positivity adds prognostic information regardless of RIFLE or KDIGO classification or cutoff selection methodology. The risk of adverse events depends on the methodology of cutoff selection and AKI classification system.

[Innovative facultative seminar concepts regarding clinical teaching and preparing practice-oriented phases, such as medical clerkships and the final clinical internship from a surgical perspective]. / Innovative fakultative Seminarkonzepte besonders klinisch-praktisch ausgerichteter Lehre zur Famulatur- und PJ-Vorbereitung aus spezifisch chirurgischer Sicht.

BACKGROUND: Practice-oriented phases, such as the mandatory clinical traineeships and the final clinical internship, are of great importance in the teaching curriculum and skilful learning of medical students. AIM: With respect to the practical phases, such as clinical clerkship and medical internship, the concept of two innovative courses to prepare and evaluate these crucial training sections is presented including initial experiences from teaching practice. METHOD: A narrative review is given. RESULTS: A common aim of facultatively initiated lectures is a better qualification of medical students to fulfil the requirements of clerkship and the last practical year of the study of human medicine to facilitate taking first steps towards professional work as a clinical physician, in particular, the self-confidence of the medical students is to be substantially increased. The experiences obtained during clerkship and the last practical year influence interest, motivation and final choice for a certain medical speciality. In that respect, this period is of great importance for the whole professional career. The content of the preparation courses for the first medical clerkships and the final clinical internship provide a valuable contribution to prepare for challenging clinical work as a physician with sole responsibility. In particular, they aim to introduce students to the concept of a multiprofessional and extensive patient care. Taking into account the different practical experiences obtained in previous study sections, students are taught according to the overall aim to achieve an interdisciplinary competence in clinical care. CONCLUSION: The improvement of teaching and optimized preparation for practical phases in medical studies promotes a more successful learning process during the clerkship and last practical year.

Students' perception and learning experience in the first medical clerkship.

BACKGROUND: The German clerkship ("Famulatur") is the first phase in medical education, in which students learn from a physician's perspective. According to the German Licensing Regulations for Physicians, students shall "familiarise" with providing care. However, specific learning objectives for the clerkship are not defined, although the acquisition of different competencies is implicitly demanded. Therefore, an additional understanding of the clerkship students' learning experience is needed. The goal of this study is to explore the student's learning perspective and experiences in the clerkship. METHODS: Twelve guideline-based interviews were conducted with third year medical students. All participants completed their first clerkship. A qualitative content analysis was performed. The inductively identified categories were transferred into a quantitative questionnaire using a 5-point Likert-scale to explore their relevance in a validation cohort. The questionnaire was completed by 222 clinical students of the Otto-von-Guericke-Universität Magdeburg. RESULTS: The qualitative analysis led to 26 individual items assigned to 4 main categories that describe the clerkship experience: 1) "coping with insecurities", 2) "the clerkship as a social arrangement", 3) "the clerkship as a learning opportunity" and 4) "the clerkship as a teaching opportunity". In the quantitative validation cohort, category one yielded a well-balanced result (median 3 = "neither agree nor disagree"; IQR 2-4), items addressed in categories 2-4 were generally supported by the students, predominantly selecting "strongly agree" or "agree" (Median 2; IQR 1-2 for each category). Students rated the role of the clinical team as especially important for their learning success and feared exclusion or negative reactions. CONCLUSIONS: The medical clerkship provides an institutional, professional, and social framework, in which students are learning. Insecurities arose from curricular inconsistencies, a high dependency on the clinical team as well as the absence of specific learning objectives. Therefore, a better curricular integration regarding the semester structure and the learning objectives of the German clerkship is needed.

Digitalization of presence events in the COVID-19 pandemia - the lecturers' perspective.

Objective: Due to the COVID-19 pandemic a large part of attendance in medical education became impossible for reasons of disease control. Teachers had to switch to online courses at short notice. The associated developmental push of digital teaching methods, such as online teaching, has anticipated changes, some of which are tantamount to establishment. This study examines the experiences and effects of these changes from the teachers' perspective. Methods: We conducted ten guideline-based anonymized e-mail interviews with lecturers of the Medical Faculty of the Otto-von-Guericke University Magdeburg. Questions were asked on the subject areas of advantages and disadvantages, teaching experience and the future of digital teaching. The qualitative evaluation was based on Mayring. Results: The assessment of the digitization of face-to-face courses could be described by the inductively formed categories "social aspects", "methodological aspects", "institutional aspects", "technical aspects" and "temporal-spatial aspects". These revealed in particular concerns about the lack of personal exchange, temporal-spatial advantages, technical barriers and disagreement about the future role of digital teaching. Conclusion: In the context of the COVID-19 pandemic, face-to-face courses were replaced by online teaching, which is currently an accepted part of the curriculum. The results show, that teachers were able to implement the comprehensive ad-hoc digitization of theoretical courses well, although previously known problem areas were aggravated. Furthermore, a fundamental examination of the future role of digitized courses in medical education must take place.

What understanding of economics do medical students have?

Introduction: Economic topics appear in the medical studies curriculum at different times. Despite socio-political relevance, there is hardly any information about the degree of understanding that medical students have of "economics in medicine". The present study addresses the questions: What understanding of "economics in medicine" do medical students have before the start of the Practical Year? To what extent is economic teaching content understood as "economization" from outside the profession? Method: Magdeburg medical students in the 5th year of study, who participated in preparatory seminars for the Practical Year (PY) in 2014 and 2015 (60 participants each), assessed the relevance of various seminar topics four months prior to the start of the semester. On the basis of a three-stage qualitative-reconstructive partial evaluation, students' economic understanding is explored through secondary analysis: deductive derivation of the analysis units; integrative basic method ("segmentation", "micro-linguistic detailed analysis", "central theme"); development of a theoretical model by placing the central themes in context following Grounded Theory. Results: Based on the theory, 19 free-text answers with economic reference were identified from the total of all free-text answers. Each answer was assigned to at least one of a total of six themes of the students' understanding of economics: de-professionalizing economization, deciding and working economically, ambivalent requirements for efficiency and equity, the doctor as an entrepreneur, economics as relevant learning content, PY as a conflict-laden setting for economized working and learning. The theoretical model contains social, praxeological and professional references, which can themselves be ambivalent and conflicting. Conclusion: Despite their critical attitude, the surveyed medical students are neither hostile to economics nor do they regard economics in medicine as a taboo subject. Economic learning content is recognized as relevant. Educational formats that tackle the tension between patient and system orientation in a problem-oriented manner can be a productive setting for economic reflection.

[Train-the-Trainer: Professionalisation of Didactics in Daily Clinical Routine - the Personal Perception of Clinical Teaching Staff with Respect to Didactic Competence and the Framework Conditions of Teaching]. / Train-the-Trainer: Professionalisierung der Lehre im klinischen Alltag ­ Selbsteinschätzung Lehrender zur didaktischen Kompetenz und den Rahmenbedingungen des Unterrichts.

BACKGROUND: Teaching training programs contribute to improving the quality of medical education. In a course of the Train-the-Trainer (TTT) concept of the Surgical Working Group for Teaching, teachers (TN) from different medical professions and career levels were taught together. AIM OF THE WORK: Assessments of teaching activities in everyday clinical practice of residents (AÄ), senior staff (OÄ) and nurses (KP), their perception of teaching obstacles and requirements to improve teaching. MATERIAL AND METHODS: Prior to the beginning of the course, biographical data, previous teaching experiences, teaching obstacles as well as their notions to improve teaching in the daily clinical routine were requested. Upon completion, the participants were asked to rate the course. The answers to the closed and open questions were evaluated quantitatively and qualitatively. RESULTS: From 2014 to 2017, six basic courses (TTT-A) were conducted at three locations. 97 participants participated in the surveys (AÄ n = 44, OÄ n = 19, KP n = 17). More than two-thirds declared previously acquired teaching knowledge. There were no significant differences between medical and nursing staff. While AÄ and KP primarily taught at the bedside, OÄ taught mainly in the context of lectures, electives and seminars. Only a small proportion of all occupational groups felt well prepared for teaching in everyday clinical practice. The main drawbacks were lack of time and staff, too many students per group and too little teaching knowledge. Nearly two-thirds of the AÄ found teaching in general as a strong or moderate burden, compared to about 50% of the OÄ and 60% KP. Aspirations for improvement of teaching included more precise characterisation of the learning objectives, greater appreciation of teaching as a whole, and regular measures to make teaching professional. DISCUSSION: Occupational group-related differences in everyday clinical practice and individual career progression, impact type, implementation and perception of the teaching activity. By focusing on learning objectives and essential teaching methods and examination formats relevant to teaching at the bedside, teacher training programs across professional groups can contribute to knowledge and expertise growth. Indications of a sustainable effect encourage the continuation and further development of the TTT concept.

Impact of internal and external electrical cardioversion on cardiac specific enzymes and inflammation in patients with atrial fibrillation and heart failure.

BACKGROUND: Implantable cardioverter/defibrillator (ICD) shocks can cause myocardial injury, contributing to the progression of the underlying heart disease. The aim was to evaluate whether internal electrical cardioversion (int-CV) via the ICD or conventional external CV (ext-CV) of persistent atrial fibrillation (AF) in heart failure (HF) patients induces myocardial injury and initiates inflammation. METHODS AND RESULTS: A total of 115 HF patients with an ejection fraction between 20% and 45% were prospectively enrolled. Fifty-one patients were excluded due to failure of electrical CV at the first attempt as well as early relapse of AF within 8h after CV. The int-CV group consisted of 22 and the ext-CV group of 42 patients. Baseline values of high sensitive troponin T (hsTnT), interleukin (IL)-6, and C-reactive protein (CRP) did not differ significantly in both groups, whereas baseline N-terminal pro B-type natriuretic peptide (NT-pro BNP) was significantly lower in the ext-CV group. Eight hours after CV, the level of hsTnT increased significantly in the int-CV group, whereas no significant change was observed in the ext-CV group. Furthermore, CV significantly increased IL-6 and CRP in the int-CV group, whereas an insignificant increase could be documented in the ext-CV group. Due to electrical CV in both groups, the NT-pro BNP levels significantly declined in approximately the same content (int-CV 29% vs. ext-CV 36%). CONCLUSIONS: The significant increase in hsTnT, IL-6, and CRP in patients who underwent int-CV compared to those undergoing ext-CV may suggest that int-CV causes significant myocardial damage and induces systemic inflammation.

[Creating Enthusiasm for Surgery - Perceptions of the Impact of Undergraduate Practical Education (Clerkship) for Occupational Choices]. / Für Chirurgie begeistern ­ Einflüsse der Famulatur aus Sicht Studierender auf eine spätere Fachpräferenz.

Background/Aim Surgical and other disciplines have been noticing difficulties in recruiting junior staff for several years. In response to a decrease in interest within study courses, surgical associations recommend better supervision during undergraduate practical education as "clerkships" in order to increase the attractiveness of surgery. This clerkship has an initiation function, as students for the first time - albeit marginally - can act as physicians. The aim of this study was to investigate the impact of clerkships on the disciplinary orientations and preferences of undergraduates' perceptions of specialist training. Methods Medical students of the Otto-von-Guericke University Medical School at Magdeburg were interviewed at 4 different time points in their clinical training (n = 373). The questionnaire included different dimensions on i) their choice of the subjects of clerkships and ii) on their clerkship experiences. Questions were subdivided into 5 basic topics, including 5 options to answer according to "Likert's scale" ranging from 1 to 5 ("completely true" to "does not apply at all"). Data were statistically analysed. Results Clerkships are an important component of medical studies. Undergraduate medical students deliberately use clerkships to get to know and to discriminate between medical disciplines they consider as possible choices for later specialisation. Their own assessment as well as reported experiences of specific clinics, departments or supervisors influence decision-making with regard to medical disciplines and locations/institutions for clerkships. The contents of the clerkships is expected to be closely related to the medical curricula. Students expect a detailed insight and practical, cross-departmental, interdisciplinary integration and collaboration in the medical discipline selected for clerkship. Clerkship experience in surgery affects the students' preference for surgical disciplines. They are a relevant predictor. Conclusion High-quality teaching - an important part of practical undergraduate training (clerkship) is effective in fostering a subsequent surgical orientation. Preference for surgical specialisation can be strengthened during medical studies by preparing seminars and extended practical experiences during clerkship.

Targeting of Extracellular RNA Reduces Edema Formation and Infarct Size and Improves Survival After Myocardial Infarction in Mice.

BACKGROUND: Following myocardial infarction (MI), peri-infarct myocardial edema formation further impairs cardiac function. Extracellular RNA (eRNA) released from injured cells strongly increases vascular permeability. This study aimed to assess the role of eRNA in MI-induced cardiac edema formation, infarct size, cardiac function, and survival after acute MI and to evaluate the therapeutic potential of ribonuclease 1 (RNase-1) treatment as an eRNA-degrading intervention. METHODS AND RESULTS: C57BL/6J mice were subjected to MI by permanent ligation of the left anterior descending coronary artery. Plasma eRNA levels were significantly increased compared with those in controls starting from 30 minutes after ligation. Systemic application of RNase-1, but not DNase, significantly reduced myocardial edema formation 24 hours after ligation compared with controls. Consequently, eRNA degradation by RNase-1 significantly improved the perfusion of collateral arteries in the border zone of the infarcted myocardium 24 hours after ligation of the left anterior descending coronary artery, as detected by micro-computed tomography imaging. Although there was no significant difference in the area at risk, the area of vital myocardium was markedly larger in mice treated with RNase-1 compared with controls, as detected by Evans blue and 2,3,5-triphenyltetrazolium chloride staining. The increase in viable myocardium was associated with significantly preserved left ventricular function, as assessed by echocardiography. Moreover, RNase-1 significantly improved 8-week survival following MI. CONCLUSIONS: eRNA is an unrecognized permeability factor in vivo, associated with myocardial edema formation after acute MI. RNase-1 counteracts eRNA-induced edema formation and preserves perfusion of the infarction border zone, reducing infarct size and protecting cardiac function after MI.

Preparation courses for medical clerkships and the final clinical internship in medical education - The Magdeburg Curriculum for Healthcare Competence.

BACKGROUND/GOALS: Supporting medical students entering their internships - the clinical clerkship and the internship "final clinical year" (Praktisches Jahr, PJ) - the seminars "Ready for Clerkship" and "Ready for PJ" were held for the first time in 2014 and continued successfully in 2015. These seminars are part of the "Magdeburg Curriculum for Healthcare Competence" (Magdeburger Curriculum zur Versorgungskompetenz, MCV). The concept comprises three main issues: "Understanding interdisciplinary clinical procedures", "Interprofessional collaboration", and "Individual cases and their reference to the system." The aim of the seminar series is to prepare students as medical trainees for their role in the practice-oriented clinical clerkship and PJ, respectively. METHODS: Quality assurance evaluations and didactic research are integral parts of the seminars. In preparation for the "Ready for PJ" seminar a needs assessment was conducted. The seminars were rated by the participants using an anonymized questionnaire consisting of a 5-choice Likert scale (ranging from 1=fully agree to 5=fully disagree) and spaces for comments that was generated by the evaluation software Evasys. RESULTS: The results are presented for the preparatory seminars "Ready for Clerkship" and "Fit für PJ" held in 2014 and 2015. Overall, the students regarded the facultative courses as very good preparation for the clerkship as well as for the PJ. The three-dimensional main curricular concept of the MCV was recognized in the evaluation as a valuable educational approach. Interprofessional collaboration, taught by instructors focussing in teamwork between disciplines, was scored positively and highly valued. CONCLUSIONS: The "Magdeburg Curriculum for Healthcare Competence" (MCV) integrates clerkship and PJ in a framing educational concept and allows students a better appreciation of their role in patient care and the tasks that they will face. The MCV concept can be utilized in other practice-oriented phases (nursing internship, bed-side teaching, block internships).

Western diet in ApoE-LDLR double-deficient mouse model of atherosclerosis leads to hepatic steatosis, fibrosis, and tumorigenesis.

Nonalcoholic fatty liver disease has been linked to cardiovascular diseases and atherosclerosis. The aim of the current study was to characterize the hepatic pathology leading to fibrosis and tumors in a murine model of atherosclerosis. Male apolipoprotein E/low-density lipoprotein receptor double-knockout mice (AL) mice were fed with a high fat and high cholesterol western diet for 35 weeks (AL mice on WD). Protein and mRNA analysis as well as micro-computed tomography (micro-CT) were performed to assess oxidative stress, liver damage, inflammation, fibrosis, signaling pathways, vascularization, and tumorigenesis. Controls were chosen to distinguish between genetically and dietary effects in steatohepatitis and associated tumorigenesis. Hepatic inflammation and dyslipidemia were increased in AL mice on WD compared with wild-type mice on WD. Uniquely, AL mice on WD showed a spontaneous development of tumors (30% of cases) and thickening of intrahepatic vessel walls. Functionally relevant underlying signaling pathways such as NF-κB, Stat3, JNK, and AKT were differentially regulated between AL and wild-type mice on WD. Micro-CT was capable of visualizing and quantitatively distinguishing tumor neovascularization from vascularization in non-neoplastic liver tissue. AL mice on WD diet represent a novel model combining atherosclerosis and nonalcoholic fatty liver disease. Signaling pathways of liver cell damage and compensatory liver regeneration in combination with enhanced inflammation appear to be crucial for the spontaneous development of tumors in AL mice on WD. Micro-CT represents a new and powerful technique for the ultrastructural and three-dimensional assessment of the vascular architecture of liver tumors.

Thalidomide influences atherogenesis in aortas of ApoE(-/-)/LDLR (-/-) double knockout mice: a nano-CT study.

Plaque progression in atherosclerosis is closely connected to angiogenesis due to vasa vasorum (VV) growth. Objective of this study was to determine the unknown long-term effect of thalidomide on adventitial VV neovascularization and plaque progression using nano-focussed computed tomography (nano-CT). Proliferation and migration assays in human coronary artery endothelial cells (HCAEC) measured number of viable cells after incubation with thalidomide. Male ApoE(-/-)/LDLR(-/-) (AL) mice (n = 5) received a thalidomide containing western diet (WD) over 29 weeks. Another five male AL mice (WD without thalidomide) served as control group. Descending aortas were scanned with nano-CT at (1.5 µm)(3) isotropic voxel size. Number and area of adventitial VV as well as plaque cross sectional area were measured. Results were complemented by histology. Thalidomide inhibited proliferation and migration of HCAEC dose-dependently. VV neovascularization decreased in number per cross section (7.66 ± 0.301 vs. 8.62 ± 0.164, p < 0.001) and in cross sectional area (0.0183 ± 0.0011 vs. 0.0238 ± 0.0008 mm(2), p < 0.001). Cross sectional area of plaque decreased significantly when treated with thalidomide (0.57 ± 0.0187 vs. 0.803 ± 0.0148 mm(2), p < 0.001). Nano-CT imaging revealed a reduced plaque growth and VV neovascularization after long-term application of thalidomide. Therefore, nano-CT can be considered as a new method to detect therapeutic effects in experimental models of atherosclerosis.

Role of the phosphatase PTEN in early vascular remodeling.

BACKGROUND: The phosphatase PTEN represents an important physiological inhibitor of phosphatidylinositol-3 kinase (PI3-K)/protein kinase B (Akt) signalling, however, the functional role of PTEN in the initial phase of angioplasty-induced vascular injury remains elusive. In the present study we sought to determine PTEN's effect on vascular smooth muscle cell (VSMC) apoptosis following acute injury in vivo and in vitro. METHODS AND RESULTS: Immunohistochemistry indicated a faint basal expression and equal distribution of PTEN in uninjured rat carotid arteries. 12 h following balloon-injury, PTEN expression was strongly increased in apoptotic (TUNEL+) VSMC. In vitro, stimulation with serum or different growth factors or subjecting VSMC to cyclic stretch had no effect on PTEN expression, whereas stimulation with H2O2 robustly increased PTEN expression in a time- and dose-dependent manner. To evaluate the functional role of PTEN expression, human VSMC were transduced with WT-PTEN. Overexpression of PTEN increased the number of apoptotic VSMC (19.8%±4.4 vs. 5.6%±2.3; P<0.001) as determined by TUNEL assay. In contrast, siRNA-mediated knock-down of PTEN attenuated the basal as well as H2O2-induced apoptosis of VSMC. Mechanistically, overexpression of PTEN prevented serum-induced Akt-phosphorylation, whereas siRNA-mediated knock down of PTEN augmented Akt-activation. Moreover, co-transfection of PTEN and a constitutive active Akt mutant prevented PTEN-dependent augmentation of VSMC apoptosis, indicating, that PTEN regulates VSMC apoptosis by inhibition of Akt phosphorylation/activation. CONCLUSION: By interfering with the PI3-K/Akt-dependent survival signalling, the oxidative stress-induced up regulation of PTEN in VSMC of injured arteries augments the sensitivity of VSMC to apoptotic stimuli in the early phase following vascular injury, augmenting the initial injury and cell loss of the injured vessel wall. Thus, these data add to our understanding of PTEN's role during vascular remodelling.

Time-course analysis on the differentiation of bone marrow-derived progenitor cells into smooth muscle cells during neointima formation.

OBJECTIVE: Bone marrow-derived progenitor cells have been implicated to contribute to neointima formation, but the time course and extent of their accumulation and differentiation into vascular cells and, most importantly, the long-term contribution of bone marrow-derived progenitor cells to the vascular lesion remain undefined. METHODS AND RESULTS: Wire-induced injury of the femoral artery was performed on chimeric C57BL/6 mice transplanted with bone marrow from transgenic mice expressing enhanced green fluorescence protein, and vessels were harvested at 3 days, 1, 2, 3, 4, 6, and 16 weeks after dilatation (n=8 animals per time point). Using high-resolution microscopy, we unexpectedly found that the expression of smooth muscle cell or endothelial cell markers in enhanced green fluorescence protein positive cells was a very rare event. Indeed, most of the enhanced green fluorescence protein positive cells that accumulated during the acute inflammatory response were identified as monocytes/macrophages, and their number declined at later time points. In contrast, a substantial fraction of highly proliferative stem cell antigen-1 and CD34(+) but enhanced green fluorescence protein negative and thus locally derived cells were detected in the adventitia. CONCLUSIONS: These data provide evidence that the differentiation of bone marrow-derived progenitor cells into smooth muscle cell or endothelial cell lineages seems to be an exceedingly rare event. Moreover, the contribution of bone marrow-derived cells to the cellular compartment of the neointima is limited to a transient period of the inflammatory response.

Rapamycin attenuates hypoxia-induced pulmonary vascular remodeling and right ventricular hypertrophy in mice.

BACKGROUND: Chronic hypoxia induces pulmonary arterial hypertension (PAH). Smooth muscle cell (SMC) proliferation and hypertrophy are important contributors to the remodeling that occurs in chronic hypoxic pulmonary vasculature. We hypothesized that rapamycin (RAPA), a potent cell cycle inhibitor, prevents pulmonary hypertension in chronic hypoxic mice. METHODS: Mice were held either at normoxia (N; 21% O2) or at hypobaric hypoxia (H; 0.5 atm; ~10% O2). RAPA-treated animals (3 mg/kg*d, i.p.) were compared to animals injected with vehicle alone. Proliferative activity within the pulmonary arteries was quantified by staining for Ki67 (positive nuclei/vessel) and media area was quantified by computer-aided planimetry after immune-labeling for alpha-smooth muscle actin (pixel/vessel). The ratio of right ventricle to left ventricle plus septum (RV/[LV+S]) was used to determine right ventricular hypertrophy. RESULTS: Proliferative activity increased by 34% at day 4 in mice held under H (median: 0.38) compared to N (median: 0.28, p = 0.028) which was completely blocked by RAPA (median HO+RAPA: 0.23, p = 0.003). H-induced proliferation had leveled off within 3 weeks. At this time point media area had, however, increased by 53% from 91 (N) to 139 (H, p < 0.001) which was prevented by RAPA (H+RAPA: 102; p < 0.001). RV/[LV+S] ratio which had risen from 0.17 (N) to 0.26 (H, p < 0.001) was attenuated in the H+RAPA group (0.22, p = 0.041). For a therapeutic approach animals were exposed to H for 21 days followed by 21 days in H +/- RAPA. Forty two days of H resulted in a media area of 129 (N: 83) which was significantly attenuated in RAPA-treated mice (H+RAPA: 92). RV/[LV+S] ratios supported prevention of PH (N 0.13; H 0.27; H+RAPA 0.17). RAPA treatment of N mice did not influence any parameter examined. CONCLUSION: Therapy with rapamycin may represent a new strategy for the treatment of pulmonary hypertension.