Accurate classification of focal liver lesions is an important part of liver disease diagnostics. In clinical practice, the lesion type is often determined from the abdominal MR examination, which ...includes T2-weighted and dynamic contrast enhanced (DCE) MR images. To date, only T2-weighted images are exploited for automatic classification of focal liver lesions. In this study additional MR sequences and risk factors are used for automatic classification to improve the results and to make a step forward to a clinically useful aid for radiologists.
Clinical MRI data sets of 95 patients with in total 125 benign lesions (40 adenomas, 29 cysts and 56 hemangiomas) and 88 malignant lesions (30 hepatocellular carcinomas (HCC) and 58 metastases) were included in this study. Contrast curve, gray level histogram, and gray level co-occurrence matrix texture features were extracted from the DCE-MR and T2-weighted images. In addition, risk factors including the presence of steatosis, cirrhosis, and a known primary tumor were used as features. Fifty features with the highest ANOVA F-score were selected and fed to an extremely randomized trees classifier. The classifier evaluation was performed using the leave-one-out principle and receiver operating characteristic (ROC) curve analysis.
The overall accuracy for the classification of the five major focal liver lesion types is 0.77. The sensitivity/specificity is 0.80/0.78, 0.93/0.93, 0.84/0.82, 0.73/0.56, and 0.62/0.77 for adenoma, cyst, hemangioma, HCC, and metastasis, respectively.
The proposed classification system using features derived from clinical DCE-MR and T2-weighted images, with additional risk factors is able to differentiate five common types of lesions and is a step forward to a clinically useful aid for focal liver lesion diagnosis.
Research on exploration and exploitation is burgeoning, yet our understanding of the antecedents and consequences of both activities remains rather unclear. We advance the growing body of literature ...by focusing on the apparent differences of exploration and exploitation and examining implications for using formal (i.e., centralization and formalization) and informal (i.e., connectedness) coordination mechanisms. This study further examines how environmental aspects (i.e., dynamism and competitiveness) moderate the effectiveness of exploratory and exploitative innovation. Results indicate that centralization negatively affects exploratory innovation, whereas formalization positively influences exploitative innovation. Interestingly, connectedness within units appears to be an important antecedent of both exploratory and exploitative innovation. Furthermore, our findings reveal that pursuing exploratory innovation is more effective in dynamic environments, whereas pursuing exploitative innovation is more beneficial to a unit's financial performance in more competitive environments. Through this richer explanation and empirical assessment, we contribute to a greater clarity and better understanding of how ambidextrous organizations coordinate the development of exploratory and exploitative innovation in organizational units and successfully respond to multiple environmental conditions.
Prior studies have emphasized that structural attributes are crucial to simultaneously pursuing exploration and exploitation, yet our understanding of antecedents of ambidexterity is still limited. ...Structural differentiation can help ambidextrous organizations to maintain multiple inconsistent and conflicting demands; however, differentiated exploratory and exploitative activities need to be mobilized, coordinated, integrated, and applied. Based on this idea, we delineate formal and informal senior team integration mechanisms (e.g., contingency rewards and social integration) and formal and informal organizational integration mechanisms (e.g., cross-functional interfaces and connectedness) and examine how they mediate the relationship between structural differentiation and ambidexterity. Overall, our findings suggest that the previously asserted direct effect of structural differentiation on ambidexterity operates through informal senior team (i.e., senior team social integration) and formal organizational (i.e., cross-functional interfaces) integration mechanisms. Through this richer explanation and empirical assessment, we contribute to a greater clarity and better understanding of how organizations may effectively pursue exploration and exploitation simultaneously to achieve ambidexterity.
Recent research on management innovation, i.e. new managerial processes, practices, or structures that change the nature of managerial work, suggests it can be an important source of competitive ...advantage. In this study, we focus on management innovation at the organization level and investigate the role of leadership behaviour as a key antecedent. Due to its prominent role within organizations, top management has the ability to greatly influence management innovation. In particular, we focus on leadership behaviour and examine transformational and transactional leadership. Additionally, as contextual variables like organizational size may influence the impact of leadership, we investigate its moderating role. Findings show that both leadership behaviours contribute to management innovation. Interestingly, our study indicates that smaller, less complex, organizations benefit more from transactional leadership in realizing management innovation. On the other hand, larger organizations need to draw on transformational leaders to compensate for their complexity and allow management innovation to flourish.
Synthetic calcium phosphate (CaP) ceramics represent the most widely used biomaterials for bone regenerative treatments due to their biological performance that is characterized by bioactivity and ...osteoconductive properties. From a clinical perspective, injectable CaP cements (CPCs) are highly appealing, as CPCs can be applied using minimally invasive surgery and can be molded to optimally fill irregular bone defects. Such CPCs are prepared from a powder and a liquid component, which upon mixing form a paste that can be injected into a bone defect and hardens in situ within an appropriate clinical time window. However, a major drawback of CPCs is their poor degradability. Ideally, CPCs should degrade at a suitable pace to allow for concomitant new bone to form. To overcome this shortcoming, control over CPC degradation has been explored using multiple approaches that introduce macroporosity within CPCs. This strategy enables faster degradation of CPC by increasing the surface area available to interact with the biological surroundings, leading to accelerated new bone formation. For a comprehensive overview of the path to degradable CPCs, this review presents the experimental procedures followed for their development with specific emphasis on (bio)material properties and biological performance in pre-clinical bone defect models.
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Abstract The differences in morphological behaviour between fibroblasts cultured on smooth and nanogrooved substrata (groove depth: 5–350 nm, width: 20–1000 nm) have been evaluated in vitro . The aim ...of the study was to clarify to what extent cell guidance occurs on increasingly smaller topographies. Pattern templates were made using electron beam lithography, and were subsequently replicated in polystyrene cell culture material using solvent casting. The replicates were investigated with atomic force microscopy (AFM). After seeding with fibroblasts, morphological characteristics were investigated using scanning electron microscopy (SEM) and light microscopy, in order to obtain qualitative and quantitative information on cell alignment. AFM revealed that the nanogroove/ridge widths were replicated perfectly, although at deeper levels the grooves became more concave. The smooth substrata had no distinguishable pattern other than a roughness amplitude of 1 nm. Interestingly, microscopy and image analysis showed that fibroblast after 4 h had adjusted their shape according to nanotopographical features down to cut-off values of 100 nm width and 75 nm depth. After 24 h culturing time, fibroblasts would even align themselves on groove depths as shallow as 35 nm. It appears depth is the most essential parameter in cellular alignment on groove patterns with a pitch ratio of 1:1. On the smooth substrata, cells always spread out in a random fashion. Analysis of variance (ANOVA) demonstrated that both main parameters, topography and culturing time, were significant. We conclude that fibroblast cells cultured on nanotopography experience a threshold feature size of 35 nm, below this value contact guidance does no longer exist.
Ceramic composites and scaffolds are popular implant materials in the field of dentistry, orthopedics and plastic surgery. For bone tissue engineering especially CaP-ceramics or cements and bioactive ...glass are suitable implant materials due to their osteoconductive properties. In this review the applicability of these ceramics but also of ceramic/polymer composites for bone tissue engineering is discussed, and in particular their use as drug delivery systems.
Overall, the high density and slow biodegradability of ceramics is not beneficial for tissue engineering purposes. To address these issues, macroporosity can be introduced often in combination with osteoinductive growth factors and cells. Ceramics are good carriers for drugs, in which release patterns are strongly dependent on the chemical consistancy of the ceramic, type of drug and drug loading.
Biodegradable polymers like polylactic acid, gelatin or chitosan are used as matrices for ceramic particles or as adjuvant to calcium phosphate cements. The use of these polymers can introduce a tailored biodegradation/drug release to the ceramic material.
Organizations capable of pursuing exploration and exploitation simultaneously have been suggested to obtain superior performance. Combining both types of activities and achieving organizational ...ambidexterity, however, leads to the presence of multiple and often conflicting goals, and poses considerable challenges to senior teams in ambidextrous organizations. This study explores the role of senior team attributes and leadership behaviour in reconciling conflicting interests among senior team members and achieving organizational ambidexterity. Findings indicate that a senior team shared vision and contingency rewards are associated with a firm's ability to combine high levels of exploratory and exploitative innovations. In addition, our study shows that an executive director's transformational leadership increases the effectiveness of senior team attributes in ambidextrous organizations and moderates the effectiveness of senior team social integration and contingency rewards. Hence, our study clarifies how senior executives reconcile conflicting demands and facilitate the balancing of seemingly contradictory forces in ambidextrous organizations. Implications for literatures on senior team attributes, transformational leadership and organizational ambidexterity are discussed.
Stem cell therapy is a treatment strategy for ischaemic heart disease patients. Meta-analysis of randomized human trials showed <5% improvement in left ventricular ejection fraction (LVEF). ...Meta-analysis of available pre-clinical data of ischaemic heart disease could provide important clues to design human clinical trials.
Random-effects meta-analysis was performed on pig, dog, or sheep studies investigating the effect of cardiac stem cell therapy in ischaemic cardiomyopathy (52 studies; n = 888 animals). Endpoints were LVEF and death. Ischaemia/reperfusion infarction was performed in 23 studies and chronic occlusion in 29 studies. Pooled analysis showed a LVEF difference of 7.5% at follow-up after cell therapy vs. control (95% confidence interval, 6.2-8.9%; P < 0.001). By exploratory multivariable meta-regression, significant predictors of LVEF improvement were: cell type bone marrow mononuclear cells (BM-MNC) showed less effect than other cell types, e.g. mesenchymal stem cells; P = 0.040 and type of infarction (left anterior descending artery 8.0 vs. left circumflex artery 5.8%; P = 0.045). Cell therapy was not associated with increased mortality (P = 0.68). Sensitivity analysis showed trends towards more improvement with higher cell number (≥10(7)), chronic occlusion models, and late injections (>1 week). After follow-up of 8 weeks, the effect of cell therapy decreased to 6%.
This meta-analysis showed that large animal models are valid to predict the outcome of clinical trials. Our results showed that cell therapy is safe and leads to a preserved LVEF. Future trials should focus on cell types other than BM-MNC, large infarction, and strategies to obtain sustained effects.
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