Fatigue failure of osteocyte cellular processes: implications for the repair of bone.

The physical effects of fatigue failure caused by cyclic strain are important and for most materials well understood. However, nothing is known about this mode of failure in living cells. We developed a novel method that allowed us to apply controlled levels of cyclic displacement to networks of osteocytes in bone. We showed that under cyclic loading, fatigue failure takes place in the dendritic processes of osteocytes at cyclic strain levels as low as one tenth of the strain needed for instantaneous rupture. The number of cycles to failure was inversely correlated with the strain level. Further experiments demonstrated that these failures were not artefacts of our methods of sample preparation and testing, and that fatigue failure of cell processes also occurs in vivo. This work is significant as it is the first time it has been possible to conduct fatigue testing on cellular material of any kind. Many types of cells experience repetitive loading which may cause failure or damage requiring repair. It is clinically important to determine how cyclic strain affects cells and how they respond in order to gain a deeper understanding of the physiological processes stimulated in this manner. The more we understand about the natural repair process in bone the more targeted the intervention methods may become if disruption of the repair process occurred. Our results will help to understand how the osteocyte cell network is disrupted in the vicinity of matrix damage, a crucial step in bone remodelling

The mechanical effects of extracorporeal irradiation on bone

Extracorporeal irradiation of an excised tumour-bearing segment of bone followed by its reimplantation is a technique used in bone sarcoma surgery for limb salvage when the bone is of reasonable quality. There is no agreement among previous studies about the dose of irradiation to be given: up to 300 Gy have been used. We investigated the influence of extracorporeal irradiation on the elastic and viscoelastic properties of bone. Bone was harvested from mature cattle and subdivided into 13 groups: 12 were exposed to increasing levels of irradiation: one was not and was used as a control. The specimens, once irradiated, underwent mechanical testing in saline at 37°C. The mechanical properties of each group, including Young's modulus, storage modulus and loss modulus, were determined experimentally and compared with the control group. There were insignificant changes in all of these mechanical properties with an increasing level of irradiation. We conclude that the overall mechanical effect of high levels of extracorporeal irradiation (300 Gy) on bone is negligible. Consequently the dose can be maximised to reduce the risk of local tumour recurrence

The mechanical effect of extracorporeal irradiation on bone

Extracorporeal irradiation and re-implantation of a bone segment is a technique employed in bone sarcoma surgery for limb salvage in the setting of reasonable bone stock. There is neither consensus nor rationale given for the dosage of irradiation used in previous studies, with values of up to 300Gy applied. We investigated the influence of extracorporeal irradiation on the elastic and viscoelastic properties of bone. Bone specimens were extracted from mature cattle and subdivided into thirteen groups; twelve groups exposed to increasing levels of irradiation and a control group. The specimens, once irradiated, underwent mechanical testing in saline at 37˚C. Mechanical properties were calculated by experimental means which included Young’s Modulus, Poisson’s Ratio, Dissipation Factor, Storage Modulus, Loss Modulus and Dynamic Modulus. These were all obtained for comparison of the irradiated specimens to the control group. We found that the overall effect of increasing irradiation doses up to 300Gy seems to present negligible change, albeit negative, on the behavior of bone. However, the increase in Poisson’s ratio following extracorporeal irradiation treatment was statistically significant. Therefore, it is concluded that the overall mechanical effect of high levels of extracorporeal irradiation (300Gy) is minute, and could be administered to reduce the risk of malignancy recurrence

Collaborating with Catastrophe: The User\u27s Guide to

This thesis contends that the narrative nature of architecture gives it the potential to act as a jeremiad, taking the present day failings of society in the face of climate change and extrapolating out a potential future dystopia to instigate a critical dialogue and challenge the status quo. Here, architecture will act as a medium, as opposed to more typical literary works or photojournalism techniques which are usually associated with communicating social critique

How do 16-18-year-old adolescents experience and respond to parental terminal illness and death? : an interpretative phenomenological analysis

Approximately 41,000 young people, under the age of 18, are bereaved of a parent each year within the U.K. (Child Bereavement Network, 2014; Winston’s Wish, 2016), and a significant number of these deaths will have been preceded by a period of terminal illness (TI). Adolescents are considered to be particularly susceptible to negative psychosocial outcomes when a parent is unwell (Grabiak, Bender & Puskar, 2007), yet adolescents as a group are less likely to access mental-health services (Reardon, Harvey, Baranowska, O’Brien, Smith & Creswell, 2017). Thus, whilst adolescents of terminally ill (TI) parents may present a vulnerable group, they may also be difficult to engage and subsequently support (Bremner, 2000). There has also been little consideration of how adolescents experience parental terminal illness (PTI), particularly considering their perceptions and experiences of support during this period. This study qualitatively explores the experiences of six individuals who had a parent diagnosed with a TI during late adolescence. Their experiences are explored in terms of their understanding, processing and adjustment to their parent’s TI, both as an individual, and in the context of their wider family and social setting. Their experiences and perceptions of support are additionally explored; considering the role of supportive individuals, services and interventions. Interpretative Phenomenological Analysis was employed to analyse participant data. Participants were individuals who had a parent diagnosed with a terminal illness aged 16-18. Four superordinate themes emerged from the data: 1) ‘Changing family dynamics’ 2) ‘grappling with adolescence and adjustment to loss’ 3) ‘Barriers to feeling/being supported’ 4) ‘Living with the consequences’. Participants relate the profound impact that PTI during adolescence has had and continues to have on their lives. Whilst there are prominent threads of difficulty and distress, elements of positive change and growth are also highlighted. Implications are discussed in terms of service provision and design, including therapeutic recommendations for counselling psychologists and other professionals working with this group

Editor’s Perspective: The time value of morality

This article presents the ancient Hebrew idea of Wisdom and its implications for contemporary business

Why I Teach at an Adventist School

I teach at Southern Adventist University for two rea­ sons. First, I have a passion for the amazing things that can be accomplished when Christian men and women serve others. Second, I want to connect with students so they feel free to talk with me about anything that concerns them

Editor’s Perspective: The fusion of religion and business

This article provides a summary of the ancient Hebrew concept of emeth (truth, faithfulness) and how it is relevant to contemporary business

Why do we have to learn this stuff? Revising or developing a course using essential questions

This paper explores how the concept of “essential questions” can be used as a structural tool for revising or developing a business course such that active learning and student engagement are fostered. The concept of essential questions is different from and similar to the Socratic method. The relationship between essential questions and other course elements is discussed. An example is provided for how this approach was used in a business ethics course taught from a biblical worldview