Urachus Fistula: A Rare First Presentation of Diverticulitis

Urachus fistulas are rare, especially in adulthood. In grown-ups urachus fistulas are usually a reflection of Crohn's disease. We present a patient in whom an urachus fistula was the first presentation of diverticulitis of the sigmoid colon. The need for proper preoperative diagnostic imaging is discussed

Development and characterization of a canine oral mucosa equivalent in a serum-free environment

The objectives of this study were to develop a serum-free system for culturing canine oral keratinocytes, the construction and characterization of a canine ex vivo produced oral mucosa equivalent (EVPOME), and transduction green fluorescent protein (GFP) into keratinocytes as a post-grafting tracking marker. Dissociated canine buccal mucosa keratinocytes were cultured in a chemically defined serum-free medium, Epilife™. First-passage keratinocytes were transfected with the GFP gene using a lentiviral vector, sorted by flow cytometer and seeded onto a dermal equivalent, AlloDerm® to form EVPOMEs. The EVPOME was characterized by histology and immunohistochemistry, for p63, Ki-67, and involucrin. Laser confocal microscopy was used to locate GFP-transfected keratinocytes within the EVPOME. Cultured canine oral keratinocytes grew rapidly over the first three passages and then the proliferative rate decreased. The canine EVPOME formed a well-stratified epithelial layer. The majority of p63 and Ki-67 immunopositive cells were located in the basal layer whereas cytoplasmic involucrin expression was seen in the suprabasal layers, similar to native canine buccal mucosa. Under laser confocal microscopy, significant green fluorescence was observed throughout the EVPOME. In conclusion, canine EVPOMEs were successfully fabricated in a defined serum-free system with similar characteristics to native buccal mucosa. GFP-transfected canine oral keratinocytes could be identified within the EVPOME. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 143–153, 2004Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34436/1/30144_ftp.pd

Tissue engineering: state of the art in oral rehabilitation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74998/1/j.1365-2842.2009.01939.x.pd

Modelling interactions between quay walls and utility lines: In the inner-city of Amsterdam

The historic inner-cities in The Netherlands are largely known for their iconic channels and their accompanying quay walls, of which a significant number were constructed over 100 years ago. Due to the limited available space in the sub-surface of the urban environment, a high number of utility lines (i.e. potable water pipes and sewer systems) are situated in the vicinity of these quay walls. In recent years, a number of quay wall collapses have occured in the inner-city of Amsterdam, some of which have been attributed to utility line leakages. However, research into the interaction between inner-city quay walls and utility lines is lacking. Thus, the aim of this report is to answer the following question: "How does utility line leakage relate to deformation and failure of Amsterdam's inner-city quay walls and when does this interaction become significant?". The interaction between utility lines and inner-city quay walls works in both ways, thus the research is split up accordingly. The effects of utility line leakages on quay wall displacement and failure were qualitative studied using a literature study. The effects of quay wall displacement on utility line leakages were quantitatively studied using an analytical model. In this model, the interaction between utility line and surrounding soil was represented using a beam on a Winkler foundation, i.e. a beam supported by a distributed spring. The stiffness of the spring was represented as bi-linear, resulting from the equilibrium bearing capacity of the soil. Quay wall displacements ranging from 20 up to 100 mm were applied to the most common types and outer diameters of utility lines found in the vicinity of quay walls. Utility line leakage is deemed to occur if a predetermined threshold is passed of either maximum angular deflection, maximum allowable bending moment or maximum allowable shear force, each resulting from the utility line displacement. Although the scope of the study is the inner-city of Amsterdam, the study can be used in other cities with inner-city quay walls, given the circumstances are similar. The literature study showed that quay wall displacement and failure due to utility line leakage follows from internal erosion processes. Two requirements have to be met for instigation of internal erosion: a local head difference between the water level in the channel and the groundwater level in the soil body behind the quay wall, and an open connection in the quay wall structure in the vicinity of the aforementioned local head difference, enabling the flow of soil via water. The rise of the groundwater level can be the result of a potable water pipe leakage, but can also follow from external factors like heavy rainfall. Three forms of open connections were appointed. The first is scour protection screen leakage, which can result in erosion underneath the structure. The second is quay wall floor leakage, which can result in both erosion underneath structure and erosion in the soil body behind the quay wall. The third is sewer leakage, which can result in erosion in the soil body behind the quay wall. In the latter, the aforementioned head difference is not required. This is because the direction of groundwater flow is not towards the channel, but towards the sewer leakage, given that the sewer pipe is located below the groundwater level. Erosion underneath the quay wall floor can result in quay wall displacement towards the channel, while erosion in the soil body behind the structure can result in the formation of a subsidence pit. Both erosion underneath- as well as behind the structure can result in (further) deformations of utility lines. The former through quay wall displacement towards the channel, resulting in local soil displacement in which said utility line is embedded in. The latter trough local loss of soil, resulting in a local reduction of support. Both have the potential to result in relative utility line displacements, which can result in leakages. This process is can be denoted as a positive feedback loop. Actual failure of the quay wall due to utility line leakage can come in the form of collapse of the quay wall towards the channel or collapse of the road on top of the structure in the formed subsidence pit. Due to the dependence on external factors, quay wall failure resulting from utility line leakage can be described as a second order effect. It was found that exceedance of the maximum allowable angular deflection of the utility line joints is most likely to result in leakages. Leakage due to exceedance of maximum allowable bending moment is relatively less likely but still significant, while leakage due to exceedance of maximum allowable shear force is unlikely. In all utility lines, a higher bending stiffness resulted in a lower susceptibility to leakage. If utility lines are deemed susceptible to leakage, it is advised that these are monitored intensely.Civil Engineering | Hydraulic Engineerin