Comparison of Thiel preserved, fresh human, and animal liver tissue in terms of mechanical properties.

BACKGROUND: In medical training and research fresh human tissue is often replaced by preserved human or fresh animal tissue, due to availability and ethical reasons. Newer preservation approaches, such as the Thiel method, promise more realistic mechanical properties than conventional formaldehyde fixation. Concerning animal substitute material, porcine and bovine tissue is often chosen, as it is easily obtainable and certain similarity to human tissue is assumed. However, it has not been thoroughly investigated how Thiel preservation changes non-linear and viscoelastic behaviour of soft organ tissues. Furthermore, differences in these properties between animal tissue and human tissue have not been previously corroborated. METHODS: We conducted ramp and relaxation tensile tests on fresh human and Thiel preserved hepatic tissue, extracting strain-specific elastic moduli, and viscoelastic properties. The results for fresh human liver were then compared to corresponding results for Thiel preserved liver, as well as previously published results for porcine and bovine liver. RESULTS: Our results showed that Thiel preservation seems to be associated with increased stiffness as well as decreased viscoelastic damping behaviour. Porcine liver was stiffer than human liver with similar viscoelastic properties. Bovine liver exhibited similar stiffness as human liver, however lower viscoelastic damping. CONCLUSIONS: The differences between human and animal liver tissue, concerning their mechanical properties, can be explained by their characteristic histology. Changes in mechanical properties due to Thiel preservation might stem from altered protein cross-linking and dehydration. The results illustrate that appropriate materials for medical training systems must be selected based on which mechanical properties are relevant for the respective application.

What does the WHOQOL-Bref measure? Measurement overlap between quality of life and depressive symptomatology in chronic somatoform pain disorder.

INTRODUCTION: Quality of life has become an important outcome criterion for psychiatric interventions. Especially in chronic disorders with no complete recovery, the improvement of quality of life is an important treatment goal. Nevertheless, there are methodological problems in assessing quality of life. There is a possible measurement overlap between quality of life and psychopathology, especially depression, which may invalidate research results. This study addresses the quality of life of patients with chronic somatoform pain and its relation to depressive symptoms. METHOD: One hundred out-patients with somatoform pain disorder at the Behavioural Medicine Pain Clinic in the Department of Psychiatry of the Medical University of Vienna were diagnosed using the SCID for Diagnostic and Statistical Manual of Mental Disorder (DSM-IV). The patients filled out the World Health Organisation Quality of Life Assessment-Bref (WHOQOL-Bref) and the Beck Depression Inventory (BDI). Pain intensity (average pain, maximum pain, minimal pain) and disability (work, leisure and family life) were assessed using visual analogue scales. RESULTS: Quality of life in somatoform pain disorder was reduced compared to the norm population, especially in the physical and psychological domains. There were highly significant negative correlations between, on the one hand, depressive symptomatology (BDI) and, on the other hand, the physical quality of life domain (r=-0.655, p<0.01), the psychological domain (r=-0.735, p<0.01), the social domain (r=-0.511, p<0.01) and the environmental domain (r=-0.561, p<0.01). In all domains of the WHOQOL-Bref and in the global score, significant differences between the group of patients with severe or very severe depressive symptoms and the group with no or only mild depressive symptoms were found. DISCUSSION: While the WHOQOL-Bref showed a poor quality of life of patients with chronic somatoform pain disorder in general and especially in the physical and in the psychological domains, the high correlation of physical and psychological quality of life scores with depressive symptomatology points to a measurement overlap. It is suggested that assessment of subjective quality of life should always be checked for the influence of depressive symptomatology on the quality of life score.

Evaluation of the ankle syndesmosis: a plastination slices study.

Plastination is an excellent tool for studying different anatomical and clinical questions. This technique is unique because it offers the possibility to produce transparent slices series that can be easily processed morphometrically. It is very difficult to recognize the subtle widening of the tibiofibular syndesmosis in less severe injuries of this articulation. Proper anatomic knowledge of the syndesmosis might be helpful. The ankle syndesmosis was investigated on 20 cadaver feet by using the E12 plastination technique. Each foot was cut into 1.6-mm transverse slices and then plastinated. The following parameters (reflecting the position of the fibula in the distal tibiofibular syndesmosis) were measured: the length (LFI) and the depth of the fibular incisure (DFI); the width of the clear space (TCS) and the tibiofibular overlap (TFO); the position of the fibula regarding the anterior aspect of the tibia (A); and the width of the fibula (W). Due to the unique approach of this method, values for the position of the fibular incisure with respect to the frontal (F) and sagittal (S) plane were described for the entire syndesmosis. The prevalence of syndesmotic injury in association with sprains of the ankle is up to 11%. The data presented in the study are useful for the appreciation of the correct position of the fibula in the fibular incisure and can be correlated with standard anterior-posterior radiographies and CT examinations of the ankle joint.

Aortic arch variation analyzed by using plastination.

Different ramification patterns can be observed during the development of the aortic arch. In this study a common trunk (CT), which subsequently branched into the brachiocephalic trunk (BT) and left common carotid artery (LCCA), arose from the aortic arch. The LCCA arose from the CT 10.27 mm above the aortic arch. After crossing the ventral aspect of the trachea and esophagus, the LCCA became situated on the left side of the esophagus. The caliber and length of the main branches of the aortic arch were determined and compared to reports in the literature. This variation was discovered in the context of producing transverse body slices using an E12 plastination process.