Developing a Patient-Specific Maxillary Implant Using Additive Manufacturing and Design

Published Conference ProceedingsMaxillectomy is the surgical removal or resection of the maxilla or upper jaw bone. A total or partial maxillectomy can be performed depending on how far the tumour has spread. This paper will discuss a patient diagnosed with an aggressive tumour in half of the top jaw who had to undergo an operation to remove the hemi-maxilla and orbital floor. Due to the extent and complexity of the defect, it was decided to manufacture an anatomical model of the hard tissues for planning a possible laser-sintered titanium implant using Additive Manufacturing (AM). The CRPM had only two weeks to design and manufacture the titanium implant, due to the severity of the tumour. The anatomical model was sent to the surgeon to cut the nylon model where the bone resection was planned. Furthermore, the prosthodontist made a wax model of the planned titanium frame that was reverse- engineered and used as reference geometry in the design software.Materialise® design suite was used to design the patient-specific maxilla and cutting jig. The EOS M280 Direct Metal Laser Sintering (DMLS) system was instrumental in achieving the direct manufacturing of the bio-compatible titanium implant. The EOS P385 system was used to manufacture the pre-operation planning model as well as the cutting jig.The process chain followed to complete this case study will be discussed showing how this intervention improved the quality of life of a SA patient. Furthermore, the proposed paper and presentation will discuss the post-operation review of the patient showing the impact AM had in accelerating patient-specific implant manufacturing. The authors seek to claim a progressed level of maturity in the proposed manufacturing value chain. The claim is based on the successful completion of the analysis and synthesis of the problem , the validated proof-of-concept of the manufacturing process and the in-vivo implementation of the final product

Medical students as research participants: Student experiences, questionnaire response rates and preferred modes

Background. Research projects frequently include students, a potentially vulnerable population, as participants. Objectives. To determine University of the Free State (UFS) medical students’ experiences as research participants. Response rates to and preferences for hard copy and electronic questionnaires were also investigated. Methods. All 804 UFS undergraduate medical students in 2020 were approached to participate in this cross-sectional survey. Fourth- and fifth-year students and one-half of the third-year class were approached in person to complete anonymous hard copy questionnaires in a class setting. First- and second-year students and the other half of the third-year class were contacted electronically to complete anonymous electronic questionnaires. Results. Response rates to hard copy questionnaires were at least ~45% of the entire year group (and >70% of those to whom the questionnaire was distributed in class) compared with approximately a third of those contacted electronically. Students who responded to electronic questionnaires preferred electronic completion, whereas those who responded to hard copy questionnaires preferred the hard copy format, except fifth-year students. The majority of students (except those in their first year) had previously been approached to participate in research projects. Between a fifth and a third of all year groups indicated that they had refused participation at least once. More than a third of fifth-year students experienced insufficient time to decide on participation. Up to a quarter of third- to fifth-year groups had felt pressurised to participate. Conclusion. Hard copy questionnaires in class, the preferred data collection method for many students, produced better response rates but placed potential pressure on students to participate

Rationale for different approaches to combined melphalan and hyperthermia in regional isolated perfusion

The addition of hyperthermia (HT) to regional isolated perfusion (RIP) with Melphalan theoretically has two advantages. Firstly, heat can selectively kill cells in poorly vascularised areas that are usually not reached by the drug. Secondly, in vitro data have revealed that the effect of Melphalan is enhanced at temperatures 39-45 degrees C. However, for the simultaneous application of Melphalan and HT, as it is given in most institutes, both normal and tumour tissues within the volume are treated with both modalities. It is unclear whether-for the same heat dose-the cytoxicity of Melphalan is enhanced more in tumour tissue than in normal tissues. As the applied dose of Melphalan in RIP is selected on maximum acceptable toxicity, any enhancement of toxicity is undesired. Indeed, Melphalan application at temperatures >41 degrees C has resulted in unacceptable toxicity. In most institutes, the hyperthermia dose is reduced in comparison to application as a single-modality treatment, to allow simultaneous combination without unacceptable toxicity. In this review, the rationale for two different approaches is summarised which may make it possible to improve the benefit from the theoretical advantage of the use of HT in RIP. It is meant to stimulate discussion as a possible first step in the design of new treatment protocols. (C) 1997 Elsevier Science Ltd

Islet neogenesis is stimulated by brief occlusion of the main pancreatic duct

Objective. Current models of islet neogenesis either cause substantial pancreatic damage or continuously stimulate the pancreas, making these models unsuitable for the study of early events that occur in the neogenic process. We aimed to develop a method where the initial events that culminate in increased pancreatic endocrine mass caube studied. Design and methods. Ten 12-week-old female Wistar rats were subjected to a midline laparotomy, the pancreas was isolated and the main pancreatic duct was occluded for 60 seconds. The pancreas was released and carefully relocated within the abdomen. Ten age-, strain- and sex-matched control rats were subjected to a sham operation. The animals were killed 56 days post .occlusion, and the pancreata excised and fiXed tor histological analysis. Body, pancreatic and hepatic weights were .noted at termination. and serum was taken for analysis. The endocrine-to-exocrine. ratio was calculated and the number of endocrine cells in eacn islet from the sectioned pancreata was counted. Results. Occlusion of the main pancreatic ductfor 60 seconds results in an increase in endocrine mass. by 80% 56 days post occlusion. This constitutes an increase in endocrine units (1 - 6 cellst and in small (7 - 30 cells), medium (31 - 60 cells) and large (> 60 cells) islets by 85%, 96%, 95% and 71% respectively. Conclusion. Brief occlusion of the main pancreatic duct results in anincrease in pancreatic endocrine. mass. An increase in endocrine units and small islets is indicative of islet neogenesis. Therefore, owing to the briefness of the stimulation; this model can therefore be used to study the iniUal events that occur during the neogenic process

Biocatalytic degradation of pharmaceuticals, personal care products, industrial chemicals, steroid hormones and pesticides in a membrane distillation-enzymatic bioreactor

© 2017 Elsevier Ltd Laccase-catalyzed degradation of a broad spectrum of trace organic contaminants (TrOCs) by a membrane distillation (MD)-enzymatic membrane bioreactor (EMBR) was investigated. The MD component effectively retained TrOCs (94–99%) in the EMBR, facilitating their continuous biocatalytic degradation. Notably, the extent of TrOC degradation was strongly influenced by their molecular properties. A significant degradation (above 90%) of TrOCs containing strong electron donating functional groups (e.g., hydroxyl and amine groups) was achieved, while a moderate removal was observed for TrOCs containing electron withdrawing functional groups (e.g., amide and halogen groups). Separate addition of two redox-mediators, namely syringaldehyde and violuric acid, further improved TrOC degradation by laccase. However, a mixture of both showed a reduced performance for a few pharmaceuticals such as primidone, carbamazepine and ibuprofen. Mediator addition increased the toxicity of the media in the enzymatic bioreactor, but the membrane permeate (i.e., final effluent) was non-toxic, suggesting an added advantage of coupling MD with EMBR

'We did everything we could'- A qualitative study exploring the acceptability of maternal-fetal surgery for spina bifida to parents

OBJECTIVE: To explore the concepts and strategies parents employ when considering maternal-fetal surgery (MFS) as an option for the management of spina bifida (SB) in their fetus, and how this determines the acceptability of the intervention. METHODS: A two-centre interview study enrolling parents whose fetuses with SB were eligible for MFS. To assess differences in acceptability, parents opting for MFS (n=24) were interviewed at three different moments in time: prior to the intervention, directly after the intervention and 3-6 months after birth. Parents opting for termination of pregnancy (n=5) were interviewed only once. Themes were identified and organised in line with the framework of acceptability. RESULTS: To parents opting for MFS, the intervention was perceived as an opportunity that needed to be taken. Feelings of parental responsibility drove them to do anything in their power to improve their future child's situation. Expectations seemed to be realistic yet were driven by hope for the best outcome. None expressed decisional regret at any stage, despite substantial impact and, at times, disappointing outcomes. For the small group of participants, who decided to opt for termination of pregnancy (TOP), MFS was not perceived as an intervention that substantially could improve the quality of their future child's life. CONCLUSION: Prospective parents opting for MFS were driven by their feelings of parental responsibility. They recognise the fetus as their future child and value information and care focusing on optimising the child's future health. In the small group of parents opting for TOP, MFS was felt to offer insufficient certainty of substantial improvement in quality of life and the perceived severe impact of SB drove their decision to end the pregnancy This article is protected by copyright. All rights reserved

Interactions among multiple stressors vary with exposure duration and biological response

Coastal ecosystems are exposed to multiple anthropogenic stressors. Effective management actions would be better informed from generalized predictions of the individual, combined and interactive effects of multiple stressors; however, few generalities are shared across different meta-analyses. Using an experimental study, we present an approach for analysing regression-based designs with generalized additive models that allowed us to capture nonlinear effects of exposure duration and stressor intensity and access interactions among stressors. We tested the approach on a globally distributed marine diatom, using 72 h photosynthesis and growth assays to quantify the individual and combined effects of three common water quality stressors; photosystem II-inhibiting herbicide exposure, dissolved inorganic nitrogen (DIN) enrichment and reduced light (due to excess suspended sediment). Exposure to DIN and reduced light generally resulted in additivity, while exposure to diuron and reduced light resulted in additive, antagonistic or synergistic interactions, depending on the stressor intensity, exposure period and biological response. We thus find the context of experimental studies to be a primary driver of interactions. The experimental and modelling approaches used here bridge the gap between two-way designs and regression-based studies, which provides a way forward to identify generalities in multiple stressor interactions

Comprehensive survey of the distribution of colour and phenolics of different red grape wine vineyard blocks from the Robertson area in South Africa

CITATION: Van der Merwe, H., Nieuwoudt, H. H., De Beer, D. & Du Toit, W. J. 2012. Comprehensive survey of the distribution of colour and phenolics of different red grape wine vineyard blocks from the Robertson area in South Africa. South African Journal of Enology and Viticulture, 33(1):58-71, doi:10.21548/33-1-1307.The original publication is available at http://www.journals.ac.za/index.php/sajevColour and phenolic content of red grapes are two of the most important constituents required to produce a quality red wine. In the Robertson grape growing area, difficulty is sometimes experienced with colour development of grapes. This is especially linked to location and most probably greatly influenced by season. Forty four vineyard blocks of the cultivars Pinotage, Merlot, Cabernet Sauvignon and Shiraz, were studied over 3 seasons primarily to focus on colour and phenolic content, but secondly on total soluble solids, titratable acidity and pH of the grapes. High performance liquid chromatography and spectrophotometric methods were used to determine various colour and phenolic parameters present at harvest. This data was used to indicate how colour and phenolic constitution of a part of the Robertson grape growing area was distributed in relation to various factors, such as cultivar and season. GPS points were used to map data for the blocks visually. Results showed variable colour and phenolic content for these grapes based on blocks and phenolic compounds investigated. Shiraz displayed a wider distribution of certain phenolic compounds over the three seasons than the other 3 cultivars. Seasonality had a great influence on these results, with outlying blocks being identified.http://www.journals.ac.za/index.php/sajev/article/view/1307Publisher's versio