Stretch-induced upregulation of connective tissue growth factor in rabbit cardiomyocytes.

Connective Tissue Growth Factor (CTGF, CCN2) is considered to play an important role in cardiac remodelling. We studied whether stretch is a primary stimulus to induce CTGF expression in vivo in rabbit heart, and in vitro in isolated cardiomyocytes and fibroblasts. Twenty weeks of combined volume and pressure overload resulted in eccentric left ventricular (LV) hypertrophy, with increased LV internal diameter (+36 %) and LV weight (+53 %). Myocardial CTGF mRNA and protein levels were substantially increased in the overloaded animals. In isolated adult rabbit cardiomyocytes, cyclic stretch strongly induced CTGF mRNA expression (2.9-fold at 48 h), whereas in cardiac fibroblasts CTGF-induction was transient and modest (1.4-fold after 4 h). Conditioned medium from stretched fibroblasts induced CTGF mRNA expression in non-stretched cardiomyocytes (2.3-fold at 48 h). Our findings indicate that stretch is an important primary trigger for CTGF-induction in the overloaded heart.

Computer supported collaborative learning in a clerkship: an exploratory study on the relation of discussion activity and revision of critical appraisal papers.

BACKGROUND: Medical students in clerkship are continuously confronted with real and relevant patient problems. To support clinical problem solving skills, students perform a Critical Appraisal of a Topic (CAT) task, often resulting in a paper. Because such a paper may contain errors, students could profit from discussion with peers, leading to paper revision. Active peer discussion by a Computer Supported Collaborative Learning (CSCL) environment show positive medical students perceptions on subjective knowledge improvement. High students' activity during discussions in a CSCL environment demonstrated higher task-focussed discussion reflecting higher levels of knowledge construction. However, it remains unclear whether high discussion activity influences students' decisions revise their CAT paper. The aim of this research is to examine whether students who revise their critical appraisal papers after discussion in a CSCL environment show more task-focussed activity and discuss more intensively on critical appraisal topics than students who do not revise their papers. METHODS: Forty-seven medical students, stratified in subgroups, participated in a structured asynchronous online discussion of individual written CAT papers on self-selected clinical problems. The discussion was structured by three critical appraisal topics. After the discussion, the students could revise their paper. For analysis purposes, all students' postings were blinded and analysed by the investigator, unaware of students characteristics and whether or not the paper was revised. Postings were counted and analysed by an independent rater, Postings were assigned into outside activity, non-task-focussed activity or task-focussed activity. Additionally, postings were assigned to one of the three critical appraisal topics. Analysis results were compared by revised and unrevised papers. RESULTS: Twenty-four papers (51.6%) were revised after the online discussion. The discussions of the revised papers showed significantly higher numbers of postings, more task-focussed activities, and more postings about the two critical appraisal topics: "appraisal of the selected article(s)", and "relevant conclusion regarding the clinical problem". CONCLUSION: A CSCL environment can support medical students in the execution and critical appraisal of authentic tasks in the clinical workplace. Revision of CAT papers appears to be related to discussions activity, more specifically reflecting high task-focussed activity of critical appraisal topics.

Easing the transition: the final year of medical education at Maastricht University.

This manuscript describes the final year of medical education at Maastricht University as it has been operating since 2006. At the time external drivers for the development of a new structure of the final year were: the desire to prepare medical students for lifelong learning, the CanMEDs that were increasingly acknowledged to state the final attainment level of medical education and an increasing recognition of the importance of learning by participating actively and by taking more responsibility. Internal drivers were students' evaluations and our wish to improve instructional design and quality control. The main aim of this new final year is to better prepare students for the transition from the medical master programme to one of the postgraduate training programmes to become a medical specialist. The final year of the medical master programme consists of two 18-weeks participation electives, one in health care and one in research. Students have a higher level of autonomy and responsibility during this final year compared to the preceding medical clerkships to enhance the transition. Portfolios are the key element in examination of SCIP and HELP. Student evaluations of the final year show high scores on coaching and instructiveness. Despite some differences between departments overall scores are very high. Suggestions to improve include the availability of work places and time for education and coaching.

Stretch-induced hypertrophy of isolated adult rabbit cardiomyocytes.

Both mechanical and humoral triggers have been put forward to explain the hypertrophic response of the challenged cardiomyocyte. The aim of the present study was to investigate whether cyclic equibiaxial stretch is a direct stimulus for isolated adult rabbit cardiomyocytes to develop hypertrophy and to explore the potential involvement of the autocrine/paracrine factors ANG II, transforming growth factor (TGF)-beta(1), and IGF-I in this process. Isolated cardiomyocytes were exposed to 10% cyclic equibiaxial stretch (1 Hz) for up to 48 h or treated with ANG II (100 nM), TGF-beta(1) (5 ng/ml), IGF-I (100 ng/ml), ANG II type 1 (AT(1)) receptor blockers, or conditioned medium of stretched fibroblasts. Cyclic stretch significantly increased cell surface area (+3.1%), protein synthesis (+21%), and brain natriuretic peptide (BNP) mRNA expression (6-fold) in cardiomyocytes. TGF-beta(1) expression increased (+42%) transiently at 4 h, whereas cardiomyocyte IGF-I expression was not detectable under all experimental conditions. The AT(1) receptor blockers candesartan and irbesartan (100 nM) did not prevent the stretch-induced hypertrophic response. Direct exposure to ANG II, TGF-beta(1), or IGF-I did not enhance cardiomyocyte BNP expression. In cardiac fibroblasts, stretch elicited a significant approximately twofold increase in TGF-beta(1) and IGF-I expression. Conditioned medium of stretched fibroblasts increased BNP expression in cardiomyocytes ( approximately 2-fold, P = 0.07). This study clearly indicates that cyclic stretch is a strong, direct trigger to induce hypertrophy in fully differentiated rabbit cardiomyocytes. The present findings do not support the notion that stretch-mediated hypertrophy of adult rabbit cardiomyocytes involves autocrine/paracrine actions of ANG II, TGF-beta(1), or IGF-I.

Dynamic straining combined with fibrin gel cell seeding improves strength of tissue-engineered small-diameter vascular grafts.

Vascular tissue engineering represents a promising approach for the development of living small-diameter vascular grafts that can be used for replacement therapy. The culture of strong human tissue-engineered (TE) vascular grafts has required long culture times, up to several months, whether or not combined with gene therapy. This article describes the culture of strong, genetically unmodified, human TE vascular grafts in 4 weeks Small-diameter vascular grafts were engineered using a fast-degrading polyglycolic acid scaffold coated with poly-4-hydroxybutyrate combined with fibrin gel and seeded with myofibroblasts isolated from discarded saphenous veins from patients undergoing coronary bypass surgery. The TE grafts were subjected to dynamic strain conditions. After 28 d of in vitro culture, the grafts demonstrated burst pressures of 903 +/- 123 mmHg. Comparison with native vessels (intact human left internal mammary arteries (LIMAs) and saphenous veins) showed no significant differences in the amount of DNA, whereas the TE vessels contained approximately 50% of the native collagen content. In the physiological pressure range, up to 300 mmHg, the mechanical properties of the TE vessels were comparable to the LIMA. In this study, we showed that dynamic conditioning combined with fibrin gel cell seeding enhances the mechanical properties of small-diameter TE grafts. These grafts might provide a promising alternative to currently used vascular replacements.

The effectiveness of massage with and without dimethyl sulfoxide in preventing pressure ulcers: a randomized, double-blind cross-over trial in patients prone to pressure ulcers.

BACKGROUND: Although guidelines advise against massage, it is one of the methods widely regarded and used by nurses to prevent pressure ulcers (PU). OBJECTIVES: The purpose of this study was to examine the effectiveness of different variations of massage in preventing pressure ulcers. METHODS: A randomized, double-blind cross-over design, in which patients of nursing homes who are prone to PU underwent two of the three possible interventions; 'position changes only', 'massaging with an indifferent cream' and 'massaging with a dimethyl sulfoxide (DMSO) cream'. RESULTS: The results of three interventions did not differ significantly. DMSO did not fulfil the expectations raised by literature and a previous pilot-study.

Massage to prevent pressure ulcers: knowledge, beliefs and practice. A cross-sectional study among nurses in the Netherlands in 1991 and 2003.

BACKGROUND: Pressure ulcers are a major problem in all areas of health care in the Netherlands. National guidelines for the prevention and treatment of pressure ulcers were originally developed in 1985 and revised in 1991 and 2002. The value of these guidelines can be questioned because it seems they are not in line with the beliefs and practice of the caregivers and only 5% of them are evidence-based. AIMS AND OBJECTIVES: To get a better insight into nurses' current knowledge, beliefs and performed practices relating to massage, a study was designed to assess changes in these three aspects after the publication of the 2002 Dutch national guidelines. The outcome was compared with the situation in 1991, the year in which the previous guidelines were published. DESIGN AND METHOD: A cross-sectional comparative study was designed using written questionnaires. Questions were formulated regarding knowledge and beliefs about prevention methods and the actual use of these methods in the prevention of pressure ulcers. The 2003-survey population consisted of nurses working in the Netherlands and was approached at random via subscriptions to Nursing News (i.e. Verpleegkunde Nieuws), a Dutch professional journal or via affiliations to an institution participating in the 2003 National Prevalence Survey of Pressure Ulcers. RESULTS AND CONCLUSIONS: Compared with the 1991 findings, the 2003 results show an improvement for the topic of pressure ulcers, but a deterioration regarding dehydration. It is obvious that the knowledge of the current CBO-guidelines on massage is still not widely distributed as it should be. Our overall conclusion is that the differences in responses between 1991 and 2003 are significant and suggest that the nurses were better informed in 2003. RELEVANCE TO CLINICAL PRACTICE: For the improvement of health care in the domain of pressure ulcer preventions, we need more than an accurate implementation of new or existing guidelines. Guidelines should also be based on qualitative, methodological well-designed studies to be evidence-based.

The effects of massage as a method to prevent pressure ulcers. A review of the literature.

General information about the effects of massage to prevent pressure ulcers is limited. A literature search was conducted to provide more detailed knowledge about the effects of massage in general and in preventing the development of pressure ulcers in particular. Using the keywords massage, rubbing, prevention of pressure ulcers/pressure ulcers, and paying particular attention to referenced articles yielded a summary of different manual massage techniques and indications/contraindications of this intervention for both healthy tissues and tissues in patients at risk for developing pressure ulcers. A careful review of this information; the clinical, physical, and pathophysiological aspects of pressure ulcers, including extrinsic and intrinsic factor; and the time-pressure relationship suggests that one type of massage may be beneficial for persons who are at risk for developing pressure ulcers. Specifically, effleurage applied with moderate pressure is the most preferred massage in the treatment of pressure ulcers, although based on currently existing studies, it cannot be proven statistically that massage is an adequate preventive method for pressure ulcers. Although many guidelines advised against use of massage in people at risk for pressure ulcers, current evidence suggests that research to increase knowledge about the mechanism behind the effects of massage as part of an individualized prevention and treatment plan should be conducted.

In vivo heat shock preconditioning mitigates calcium overload during ischaemia/reperfusion in the isolated, perfused rat heart.

Heat shock (HS) pretreatment of the heart is effective in mitigating the deleterious effects of ischaemia/reperfusion. The main objective of this study was to determine whether the beneficial effect of HS is associated with the preservation of intracellular Ca2+ handling in the ischaemic/reperfused, isolated rat heart. Twenty-four hours after raising body core temperature to 42 degrees C for 15 min, rat hearts were perfused according to Langendorff and subjected to 30 min ischaemia followed by 20 min reperfusion. Cyclic changes of cytoplasmic calcium ion [Ca2+i] levels were measured by surface fluorometry using Indo-1 AM. Reperfused HS hearts showed improved recovery of contractile function compared with control hearts: end-diastolic pressure: 45+/-11 vs. 64+/-22 mmHg; developed pressure: 72+/-12 vs. 41+/-20 mmHg; maximum rate of pressure increase (+dP/dtmax): 1,513+/-305 vs. 938+/-500 mmHg/s; maximum rate of pressure decrease (-dP/dtmax): -1,354+/-304 vs. -806+/-403 mmHg/s. HS hearts displayed a significantly lower end-diastolic cytosolic [Ca2+] ([Ca2+]i) after reinstallation of flow. The dynamic parameters of the Ca2+i transients, i.e. the maximum rate of increase/decrease (+/-dCa2+i/dtmax) and amplitude, did not differ between reperfused control and HS hearts. The novel finding of this study is that improved performance of the HS-preconditioned heart after an ischaemic insult is associated with a reduced end-diastolic Ca2+i load, and most likely, preserved Ca2+ sensitivity of the myocardial contractile machinery.

Anisotropic, three-dimensional deformation of single attached cells under compression.

Quantifying three-dimensional deformation of cells under mechanical load is relevant when studying cell deformation in relation to cellular functioning. Because most cells are anchorage dependent for normal functioning, it is desired to study cells in their attached configuration. This study reports new three-dimensional morphometric measurements of cell deformation during stepwise compression experiments with a recently developed cell loading device. The device allows global, unconfined compression of individual, attached cells under optimal environmental conditions. Three-dimensional images of fluorescently stained myoblasts were recorded with confocal microscopy and analyzed with image restoration and three-dimensional image reconstruction software to quantify cell deformation. In response to compression, cell width, cross-sectional area, and surface area increased significantly with applied strain, whereas cell volume remained constant. Interestingly, the cell and the nucleus deformed perpendicular to the direction of actin filaments present along the long axis of the cell. This strongly suggests that this anisotropic deformation can be attributed to the preferred orientation of actin filaments. A shape factor was introduced to quantify the global shape of attached cells. The increase of this factor during compression reflected the anisotropic deformation of the cell.

Proteins involved in salvage of the myocardium.

In the Western world, cardiac ischemic disease is still the most common cause of death despite significant improvements of therapeutic drugs and interventions. The fact that the heart possesses an intrinsic protection mechanism has been systematically overlooked before the 1980s. It has been clearly shown that the activation of this mechanism can reduce the infarct size after an ischemic insult. Prerequisite is the induction of the synthesis of such cardio-protective proteins as heat shock proteins (HSPs) and anti-oxidative enzymes. HSPs are involved in the maintenance of cell homeostasis by guiding the synthesis, folding and degradation of proteins. Besides, the various family members cover a broad spectrum of anti-oxidative, anti-apoptotic and anti-inflammatory activities. Although the major inducible HSP72 has received most attention, other HSPs are able to confer cardioprotection as well. In addition, it seems that there is a concerted action between the various cardio-protective proteins. One drawback is that the beneficial effects of HSPs seem to be less effective in the compromised than in the normal heart. Although clinical studies have shown that there is a therapeutic potential for HSPs in the compromised heart, major efforts are needed to fully understand the role of HSPs in these hearts and to find a safe and convenient way to activate these protective proteins.

Quantification of cytoskeletal deformation in living cells based on hierarchical feature vector matching.

The cytoskeleton is a dynamic scaffold in living cells even in the absence of externally imposed forces. In this study on cytoskeletal deformation, the applicability of hierarchical feature vector matching (HFVM), a new matching method, currently applied in space research and three-dimensional surface reconstruction, was investigated. Stably transfected CHO-K1 cells expressing green fluorescent protein (GFP) coupled to vimentin were used to visualize spontaneous movement of the vimentin cytoskeleton of individual cells using a confocal laser scanning system. We showed that, with proper parameter and configuration settings, HFVM could recognize and trace 60-70% of all image points in artificially translated, rotated, or deformed images. If only points belonging to the cytoskeleton were selected for matching purposes, the percentage of matched points increased to 98%. This high percentage of recognition also could be reached in a time series of images, in which a certain degree of bleaching of the fluorescence over the recording time of 30 min was inevitable. In these images, HFVM allowed the detection as well as the quantification of spontaneous cytoskeletal movements of up to 10% of the cell width. Therefore, HFVM appears to be a reliable method of quantifying dynamic cytoskeletal behavior in living cells.