ABSTRACT
Laying hens develop a type of osteoporosis that arises from a loss of structural bone, resulting in high incidence of fractures. In this study, a comparison of bone material properties was made for lines of hens created by divergent selection to have high and low bone strength and housed in either individual cages, with restricted mobility, or in an aviary system, with opportunity for increased mobility. Improvement of bone biomechanics in the high line hens and in aviary housing was mainly due to increased bone mass, thicker cortical bone and more medullary bone. However, bone material properties such as cortical and medullary bone mineral composition and crystallinity as well as collagen maturity did not differ between lines. However, bone material properties of birds from the different type of housing were markedly different. The cortical bone in aviary birds had a lower degree of mineralization and bone mineral was less mature and less organized than in caged birds. These differences can be explained by increased bone turnover rates due to the higher physical activity of aviary birds that stimulates bone formation and bone remodeling. Multivariate statistical analyses shows that both cortical and medullary bone contribute to breaking strengthThe cortical thickness was the single most important contributor while its degree of mineralization and porosity had a smaller contribution. Bone properties had poorer correlations with mechanical properties in cage birds than in aviary birds presumably due to the greater number of structural defects of cortical bone in cage birds.
Subject(s)
Bone Density , Bone and Bones/metabolism , Oviposition/physiology , Physical Conditioning, Animal/physiology , Tibia/physiology , Animals , Biomechanical Phenomena , Chickens , Female , Tibia/metabolismABSTRACT
Visual Analogue Scales (VAS) provide a simple technique for measuring subjective experience. They have been established as valid and reliable in a range of clinical and research applications, although there is also evidence of increased error and decreased sensitivity when used with some subject groups. Decisions concerned with the choice of scoring interval, experimental design, and statistical analysis for VAS have in some instances been based on convention, assumption and convenience, highlighting the need for more comprehensive assessment of individual scales if this versatile and sensitive measurement technique is to be used to full advantage.
Subject(s)
Psychological Tests , Humans , Mental Disorders/diagnosis , Pain MeasurementABSTRACT
A 50-year-old patient with breast cancer was about to withdraw from her adjuvant chemotherapy regimen because of a long-standing phobia about being injected, which had been compounded by anxieties that were associated with the severe side-effects of adjuvant chemotherapy. She experienced a conditioned nausea response to hospital and medical situations. A psychological programme that incorporated relaxation training, systematic desensitization by way of the patient's visual imagination and videotape modelling, allowed her to complete the course of chemotherapy and to feel less anxious in hospital and medical settings.
