SLM von Polylactiden zur Herstellung von resorbierbaren Implantaten

Rapid Manufacturing von individuellen Implantaten mittels Selective Laser Melting (SLM) wurde für metallische Standardwerkstoffe in der Medizintechnik (Titanlegierungen, Kobalt-Chrom-Legierungen, Stahl) realisiert. Dies sind permanente Implantate, die entweder dauerhaft im Körper verbleiben oder in einer zweiten Operation entfernt werden. Eine vom ILT mittels SLM hergestellte Hüftpfanne aus TiAl6V4 konnte bereits erfolgreich im Patienten implantiert werden. Die regenerative Therapie ist jedoch die klinisch bevorzugte Strategie. Das bedeutet, dass der Selbstheilungsprozess des menschlichen Körpers für die Heilung von großen Knochendefekten genutzt wird. Ein neuer Ansatz zur Implantatfertigung folgt dieser Strategie. Der SLM-Prozess wird für die Verarbeitung von bioresorbierbaren Werkstoffen entwickelt um individuelle Implantate zu fertigen, die im Körper abgebaut und durch körpereigenes Knochengewebe ersetzt werden. Diese Arbeit beschreibt die Qualifizierung des SLM Verfahrens für die Verarbeitung von einem Kompositmaterial aus Polylactid / β-Tricalciumphosphat (PDLLA/β-TCP).

Assessing collective defensive performances in football: A Qualitative Comparative Analysis of central back pairs

Ahead of the World Cup in Brazil the crucial question for the Swiss national coach is the nomination of the starting eleven central back pair. A fuzzy set Qualitative Comparative Analysis assesses the defensive performances of different Swiss central back pairs during the World Cup campaign (2011 – 2014). This analysis advises Ottmar Hitzfeld to nominate Steve von Bergen and Johan Djourou as the starting eleven central back pair. The alternative with a substantially weaker empirical validity would be Johan Djourou together with Phillippe Senderos. Furthermore, this paper aims to be a step forward in mainstream football analytics. It analyses the undervalued and understudied defense (Anderson and Sally 2012, Statsbomb 2013) by explaining collective defensive performances instead of assessments of individual player or team performances. However, a qualitatively (better defensive metrics) and quantitatively (more games) improved and extended data set would allow for a more sophisticated analysis of collective defensive performances.

Histamine reduces flash sensitivity of on ganglion cells in the primate retina.

PURPOSE. In Old World primates, the retina receives input from histaminergic neurons in the posterior hypothalamus. They are a subset of the neurons that project throughout the central nervous system and fire maximally during the day. The contribution of these neurons to vision, was examined by applying histamine to a dark-adapted, superfused baboon eye cup preparation while making extracellular recordings from peripheral retinal ganglion cells. METHODS. The stimuli were 5-ms, 560-nm, weak, full-field flashes in the low scotopic range. Ganglion cells with sustained and transient ON responses and two cell types with OFF responses were distinguished; their responses were recorded with a 16-channel microelectrode array. RESULTS. Low micromolar doses of histamine decreased the rate of maintained firing and the light sensitivity of ON ganglion cells. Both sustained and transient ON cells responded similarly to histamine. There were no statistically significant effects of histamine in a more limited study of OFF ganglion cells. The response latencies of ON cells were approximately 5 ms slower, on average, when histamine was present. Histamine also reduced the signal-to-noise ratio of ON cells, particularly in those cells with a histamine-induced increase in maintained activity. CONCLUSIONS. A major action of histamine released from retinopetal axons under dark-adapted conditions, when rod signals dominate the response, is to reduce the sensitivity of ON ganglion cells to light flashes. These findings may relate to reports that humans are less sensitive to light stimuli in the scotopic range during the day, when histamine release in the retina is expected to be at its maximum.

The Power of Tolerance. A Debate

We invoke the ideal of tolerance in response to conflict, but what does it mean to answer conflict with a call for tolerance? Is tolerance a way of resolving conflicts or a means of sustaining them? Does it transform conflicts into productive tensions, or does it perpetuate underlying power relations? To what extent does tolerance hide its involvement with power and act as a form of depoliticization? Wendy Brown and Rainer Forst debate the uses and misuses of tolerance, an exchange that highlights the fundamental differences in their critical practice despite a number of political similarities. Both scholars address the normative premises, limits, and political implications of various conceptions of tolerance. Brown offers a genealogical critique of contemporary discourses on tolerance in Western liberal societies, focusing on their inherent ties to colonialism and imperialism, and Forst reconstructs an intellectual history of tolerance that attempts to redeem its political virtue in democratic societies. Brown and Forst work from different perspectives and traditions, yet they each remain wary of the subjection and abnegation embodied in toleration discourses, among other issues. The result is a dialogue rich in critical and conceptual reflections on power, justice, discourse, rationality, and identity.

X-ray image calibration and its application to clinical orthopedics.

X-ray imaging is one of the most commonly used medical imaging modality. Albeit X-ray radiographs provide important clinical information for diagnosis, planning and post-operative follow-up, the challenging interpretation due to its 2D projection characteristics and the unknown magnification factor constrain the full benefit of X-ray imaging. In order to overcome these drawbacks, we proposed here an easy-to-use X-ray calibration object and developed an optimization method to robustly find correspondences between the 3D fiducials of the calibration object and their 2D projections. In this work we present all the details of this outlined concept. Moreover, we demonstrate the potential of using such a method to precisely extract information from calibrated X-ray radiographs for two different orthopedic applications: post-operative acetabular cup implant orientation measurement and 3D vertebral body displacement measurement during preoperative traction tests. In the first application, we have achieved a clinically acceptable accuracy of below 1° for both anteversion and inclination angles, where in the second application an average displacement of 8.06±3.71 mm was measured. The results of both applications indicate the importance of using X-ray calibration in the clinical routine.

Reconstruction of femoro-acetabular offsets using a short-stem

PURPOSE Despite the fact that new and modern short-stems allow bone sparing and saving of soft-tissue and muscles, we still face the challenge of anatomically reconstructing the femoro-acetabular offset and leg length. Therefore a radiological and clinical analysis of a short-stem reconstruction of the femoro-acetabular offset and leg length was performed. METHODS Using an antero-lateral approach, the optimys short-stem (Mathys Ltd, Bettlach, Switzerland) was implanted in 114 consecutive patients in combination with a cementless cup (Fitmore, Zimmer, Indiana, USA; vitamys RM Pressfit, Mathys Ltd, Bettlach, Switzerland). Pre- and postoperative X-rays were done in a standardized technique. In order to better analyse and compare X-ray data a special double coordinate system was developed for measuring femoral- and acetabular offset. Harris hip score was assessed before and six weeks after surgery. Visual analogue scale (VAS) satisfaction, leg length difference and the existence of gluteal muscle insufficiency were also examined. RESULTS Postoperative femoral offset was significantly increased by a mean of 5.8 mm. At the same time cup implantation significantly decreased the acetabular offset by a mean of 3.7 mm, which resulted in an increased combined femoro-acetabular offset of 2.1 mm. Postoperatively, 81.7 % of patients presented with equal leg length. The maximum discrepancy was 10 mm. Clinically, there were no signs of gluteal insufficiency. No luxation occurred during hospitalization. The Harris hip score improved from 47.3 before to 90.1 points already at six weeks after surgery while the mean VAS satisfaction was 9.1. CONCLUSION The analysis showed that loss of femoro-acetabular offset can be reduced with an appropriate stem design. Consequently, a good reconstruction of anatomy and leg length can be achieved. In the early postoperative stage the clinical results are excellent.

A complete-pelvis segmentation framework for image-free total hip arthroplasty (THA): methodology and clinical study

Background Complete-pelvis segmentation in antero-posterior pelvic radiographs is required to create a patient-specific three-dimensional pelvis model for surgical planning and postoperative assessment in image-free navigation of total hip arthroplasty. Methods A fast and robust framework for accurately segmenting the complete pelvis is presented, consisting of two consecutive modules. In the first module, a three-stage method was developed to delineate the left hemipelvis based on statistical appearance and shape models. To handle complex pelvic structures, anatomy-specific information processing techniques were employed. As the input to the second module, the delineated left hemi-pelvis was then reflected about an estimated symmetry line of the radiograph to initialize the right hemi-pelvis segmentation. The right hemi-pelvis was segmented by the same three-stage method, Results Two experiments conducted on respectively 143 and 40 AP radiographs demonstrated a mean segmentation accuracy of 1.61±0.68 mm. A clinical study to investigate the postoperative assessment of acetabular cup orientations based on the proposed framework revealed an average accuracy of 1.2°±0.9° and 1.6°±1.4° for anteversion and inclination, respectively. Delineation of each radiograph costs less than one minute. Conclusions Despite further validation needed, the preliminary results implied the underlying clinical applicability of the proposed framework for image-free THA.

TIMS measurements of full range of natural Ca isotopes with internally consistent fractionation correction

This study presents static measurements of the Ca isotopic composition of standard reference materials SRM 915 a/b on a Triton Plus™ thermal ionization mass spectrometer with a specially developed Faraday cup array allowing simultaneous measurement of 40Ca and 48Ca. The total amount of Ca in all analyses was kept < 1 µg. With this setup the measurement uncertainties were 0.06 ‰ for 40Ca/44Ca and 0.12 ‰ for 48Ca/40Ca. Measuring all isotopes simultaneously better allows to test the internal consistency of different Ca isotope abundances reported in the literature. The exponential law was observed to correct incompletely instrumental mass fractionation. An improved fractionation correction based on the exponential law is proposed. It changes the 40Ca/44Ca ratio of SRM 915a (corrected relative to 42Ca/44Ca = 0.31221; 48Ca/44Ca = 0.08871) from 47.1635 ± 0.0028 to 47.1649 ± 0.0047. The measurements of SRM 915b were performed with different analytical conditions (runs were prolonged till complete filament load depletion). Even if the 40Ca/44Ca ratio of SRM 915b, when corrected with the simple exponential law, appears different (47.1532 ± 0.0038) from that of SRM 915a, it becomes coincident (47.1613 ± 0.0028) when corrected with a second-order refinement. This supports the use of the improved exponential law to obtain internally consistent Ca isotope ratio for natural samples.

The use of special stains at two dermatopathology laboratories in East Africa.

BACKGROUND Histopathology is often essential to establish an accurate diagnosis. Pathology laboratories are scarce in most Sub-Saharan Africa where dermatopathology is a developing field. In resource-poor countries, most specimens are analyzed only after hematoxylin and eosin staining. The availability of special stains is very limited and restricted to only few centers. The aim of this study is to analyze the extent of dermatopathological cases which can be adequately diagnosed after hematoxylin and eosin alone. Secondly, to investigate which cases required further special stains. METHODS All skin specimens submitted to two University Hospitals (Tanzania and Kenya) were included in this study. All specimens were first analyzed with hematoxylin and eosin and a diagnosis established when possible. All cases in which an accurate diagnosis after hematoxylin and eosin only was not possible, were registered and evaluated after further special stains. RESULTS A total of 386 specimens were examined. A proper histopathologic diagnosis with hematoxylin and eosin alone was possible in 344 (89.1%) samples. In 45 (11.6%) cases, mostly skin infections, further special stains were necessary. CONCLUSION A proper histopathologic diagnosis was possible after hematoxylin and eosin alone in almost 90% of the specimens submitted to the two laboratories in Sub-Saharan Africa.

Prior knowledge of the clinical picture does not introduce bias in the histopathologic diagnosis of melanocytic skin lesions

A common debate among dermatopathologists is that prior knowledge of the clinical picture of melanocytic skin neoplasms may introduce a potential bias in the histopathologic examination. Histologic slides from 99 melanocytic skin neoplasms were circulated among 10 clinical dermatologists, all of them formally trained and board-certified dermatopathologists: 5 dermatopathologists had clinical images available after a 'blind' examination (Group 1); the other 5 had clinical images available before microscopic examination (Group 2). Data from the two groups were compared regarding 'consensus' (a diagnosis in agreement by ≥4 dermatopathologists/group), chance-corrected interobserver agreement (Fleiss' k) and level of diagnostic confidence (LDC: a 1-5 arbitrary scale indicating 'increasing reliability' of any given diagnosis). Compared with Group 1 dermatopathologists, Group 2 achieved a lower number of consensus (84 vs. 90) but a higher k value (0.74 vs. 0.69) and a greater mean LDC value (4.57 vs. 4.32). The same consensus was achieved by the two groups in 81/99 cases. Spitzoid neoplasms were most frequently controversial for both groups. The histopathologic interpretation of melanocytic neoplasms seems to be not biased by the knowledge of the clinical picture before histopathologic examination.

Multibranched acquired periungual fibrokeratomas with confounding histopathologic findings resembling papillomavirus infection: a report of two cases

Acquired periungual fibrokeratomas are benign fibrous tissue tumors and are considered as the topographical variant of acquired digital fibrokeratoma. They usually present as solitary tumors. In some instance, the entity may appear in multibranched fashion. The main histopathologic features consist of acanthosis, thick collagen bundles mainly oriented in a vertical axis forming a central core, and numerous proliferating fibroblasts. In this article, we present two cases of acquired multibranched periungual fibrokeratoma and depict their varying clinical features over time. Binucleation and perinuclear halos of keratinocytes mimicking human papillomavirus (HPV) infection were detected microscopically, but there was no reactivity with HPV immunostaining. In context, anti-HPV immunostaining may be helpful in the differentiation of fibrokeratomas from HPV infection. On the other hand, it should be kept in mind that these histopathologic findings may be found in acral biopsies independent of viral effects.

Periazetabuläre Frakturen bei Hüftprothesen

Periazetabuläre Frakturen bei Hüftprothesen nehmen aufgrund der Überalterung und der zunehmenden Aktivität alter Menschen zu. Die periprothetischen Azetabulumfrakturen werden anhand der Einteilung von Letournel klassifiziert. Wenn beide Azetabulumpfeiler bei Hüftprothese betroffen sind, wird auch von einer Beckendiskontinuität gesprochen. Durch eine laterale Kompression können auch periazetabuläre Schambeinastfrakturen und/oder transiliakale Frakturen auftreten. Für die Therapieentscheidung (konservativ, alleinige Osteosynthese, Revisionshüfttotalprothese mit oder ohne zusätzliche Osteosynthese des Vorder- und/oder Hinterpfeilers) und die Zugangswahl bei operativer Versorgung werden patientenspezifische (Alter, Morbidität, Osteoporose, Aktivitätslevel des Patienten), frakturspezifische (Frakturtyp, Dislokationsausmaß, Impression des Doms oder der Hinterwand) und auch prothesenspezifische Faktoren (Art der implantierten Prothese [Hemiprothese vs. Totalprothese], Pfannenstabilität, Zeichen eines Prothesenabriebs, Ausmaß und Lokalisation einer azetabulären Lyse, Stabilität und Lysezeichen des Prothesenschafts) berücksichtigt. Bei akuten Beckendiskontinuitäten werden neben einer Osteosynthese des dorsalen Pfeilers zunehmend eine schnell ossär integrierbare Pfanne (Tantalum [„Trabecular Metal“: TM]) mit oder ohne Augment und/oder Allograft und allenfalls in einer sog. „Cup-Cage“-Technik (TM-Pfanne mit einem abstützenden Revisionsring [Burch-Schneider-Ring] analog zur Therapie von chronischen Beckendiskontinuitäten empfohlen. Bei großen Lysezonen und starken Dislokationen des vorderen Pfeilers und der quadrilateralen Fläche können intrapelvine Zugänge (modifizierter Stoppa- oder Pararectus-Zugang nach Keel) zur zusätzlichen Zuggurtungsosteosynthese des vorderen Pfeilers und Abstützung der quadrilateralen Fläche gewählt werden.

A case-control study of tea/coffee consumption and lung cancer risk

Background. Despite the increasing attention to the effects of dietary factors on lung cancer risk, epidemiological research on the role of black/green tea and coffee intake and lung cancer risk is scarce. The purpose of this study was to explore the following three hypotheses: (1) the preventive (protective) effect from lung cancer is higher in green tea than in black tea and coffee consumption. (2) brewed tea (either black or green) daily drinkers have lower odds of lung cancer than non-drinkers of brewed tea (3) regular black and green tea have more preventive effect against lung cancer than decaffeinated teas due to the synergistic effect of caffeine and other tea components. ^ Methods. Data on 1,088 lung cancer cases and 1,127 controls from an ongoing epidemiological study of lung cancer by the Department of Epidemiology of the University of Texas M.D. Anderson Cancer were analyzed. Multiple logistic regressions were performed for testing associations between frequency of specific types of tea/coffee consumption and the risk of lung cancer. ^ Results. We observed that more than a cup a week of green tea and decaffeinated black tea were significantly associated with reduced odds of lung cancer by 64% for green tea (adjusted OR = 0.44; 95% CI = 0.31–0.64), 36% for decaffeinated black tea (OR = 0.64; 95% CI = 0.45–0.90), when compared with non-drinkers and those who drank less than a cup a week. On the other hand, increasing intake of regular coffee (more than 3 cups a day) was associated with a 30% higher odds ratio of lung cancer (OR = 1.30; 95% CI = 1.01–1.09). No association was found between regular black tea, decaffeinated coffee consumption and the odds ratio of lung cancer. However, when drinkers of other tea/coffee beverages were excluded from each model in order to explore the independent effect of each type of tea/coffee, green tea and decaffeinated black tea-lung cancer associations remained but no association was observed for drinkers of regular coffee. ^ Conclusion. We report the chemopreventive effects of more than a cup a week of green tea and decaffeinated black tea on lung cancer. ^

Theory of uncertainty in illness in patients with cancer of unknown primary origin: Structure providers as antecedents of uncertainty in a population of cancer patients with an unknown primary diagnosis

Uncertainty has been found to be a major component of the cancer experience and can dramatically affect psychosocial adaptation and outcomes of a patient's disease state (McCormick, 2002). Patients with a diagnosis of Carcinoma of Unknown Primary (CUP) may experience higher levels of uncertainty due to the unpredictability of current and future symptoms, limited treatment options and an undetermined life expectancy. To date, only one study has touched upon uncertainty and its' effects on those with CUP but no information exists concerning the effects of uncertainty regarding diagnosis and treatment on the distress level and psychosocial adjustment of this population (Parker & Lenzi, 2003). ^ Mishel's Uncertainty in Illness Theory (1984) proposes that uncertainty is preceded by three variables, one of which being Structure Providers. Structure Providers include credible authority, the degree of trust and confidence the patient has with their doctor, education and social support. It was the goal of this study to examine the relationship between uncertainty and Structure Providers to support the following hypotheses: (1) There will be a negative association between credible authority and uncertainty, (2) There will be a negative association between education level and uncertainty, and (3) There will be a negative association between social support and uncertainty. ^ This cross-sectional analysis utilized data from 219 patients following their initial consultation with their oncologist. Data included the Mishel Uncertainty in Illness Scale (MUIS) which was used to determine patients' uncertainty levels, the Medical Outcomes Study-Social Support Scale (MOSS-SSS) to assess patients, levels of social support, the Patient Satisfaction Questionnaire (PSQ-18) and the Cancer Diagnostic Interview Scale (CDIS) to measure credible authority and general demographic information to assess age, education, marital status and ethnicity. ^ In this study we found that uncertainty levels were generally higher in this sample as compared to other types of cancer populations. And while our results seemed to support most of our hypothesis, we were only able to show significant associations between two. The analyses indicated that credible authority measured by both the CDIS and the PSQ was a significant predictor of uncertainty as was social support measured by the MOSS-SS. Education has shown to have an inconsistent pattern of effect in relation to uncertainty and in the current study there was not enough data to significantly support our hypothesis. ^ The results of this study generally support Mishel's Theory of Uncertainty in Illness and highlight the importance of taking into consideration patients, psychosocial factors as well as employing proper communication practices between physicians and their patients.^