Design and experimental validation of a new wheelchair seat stabilization system.

PURPOSE: Seat tilting wheelchair features can increase the comfort and safety of the user. Although many power wheelchairs have tilting mechanisms, they are often designed with a specific wheelchair model in mind. In this study, a design process for seat tilting mechanisms that can be applied to most rear-wheel drive wheelchair models is developed. METHODOLOGY: Equations were developed to describe the geometrical and load constraints that were used to size the electric actuator that powers the system and define its position. Finally, the equations were used to create the seat tilting mechanism of a prototype wheelchair, which was then tested. RESULTS: The equations yielded coherent results which showed that advantageous actuator positions from a load minimization perspective usually require dimensions that cannot be found in commercial actuators. Also, there are positions in which the load increases exponentially, which should be avoided. The tests showed that the system was able to function properly on the prototype wheelchair and that the actuator position affected the time taken for the actuator to execute different parts of the tilting movement. CONCLUSIONS: The design process presented here was successful and modelled by general equations that can be applied to most front-wheel drive wheelchairs. It presents a low-cost option for the design of seat tilting systems, which can increase their accessibility.

Developing new systems to provide improvements in assistive technologies is fundamental for social reintegration and quality of life improvement.Wheelchairs with a seat stabilization system for moving through inclined terrain can provide greater comfort and safety to the user.Adding low-cost functionalities to wheelchairs is essential to make them more accessible to people, therefore, this paper provides a design method of a new seat stabilization system applied to low-cost wheelchairs.

Systemic effects of oral tolerance in bone healing.

Bone fractures cause acute inflammation that, despite being important for initial repair, may delay the healing of the damaged bone. Parenteral injection of dietary protein has been shown to decrease inflammation and accelerate the repair of skin wounds and other inflammatory pathologies. Thus, our aim was to evaluate whether the intraperitoneal (i.p.) immunization with zein, an abundant protein in rodent chow, would favor bone healing. Wistar rats received i.p. immunization: saline (SG), adjuvant (AG) and zein associated with adjuvant (ZG). Then, a 2 mm of defect bone was performed on the right tibia, and on days 7, 14, 28 and 45 thereafter, analyses were performed. The results showed that the injection of zein reduced inflammation without impairing bone mineralization. Moreover, biomechanical tests demonstrated higher levels of maximum force (N) in ZG, indicating better mechanical resistance in relation to the others. The computerized tomography also indicated lower levels of medullary content in the ZG than in the SG, suggesting the absence of trabeculae in the medullary region in the ZG. These findings suggest that the injection of zein in previously tolerated animals may improve bone repair, leading to mechanically functional bone formation.

Effects of long-term administration of omeprazole on bone mineral density and the mechanical properties of the bone.

OBJECTIVES: Epidemiological studies have shown a relationship between long-term use of proton pump inhibitors and bone metabolism. However, this relationship has not yet become established. The aim of the present study was to analyze the mechanical properties and bone mineral density (BMD) of rats that were subjected to long-term omeprazole use. METHODS: Fifty Wistar rats weighing between 200 and 240 g were divided equally into five groups: OMP300 (omeprazole intake at a dose of 300 µmoL/kg/day); OMP200 (200 µmoL/kg/day); OMP40 (40 µmoL/kg/day); OMP10 (10 µmoL/kg/day); and Cont (control group; intake of dilution vehicle). The solutions were administered for 90 consecutive days. After the rats had been sacrificed, their BMD, the mechanical properties of the dissected femurs and their serum Ca++ levels were analyzed. RESULTS: The BMD of the OMP300 group was lower than that of the controls (p = 0.006). There was no difference on comparing the OMP200, OMP40 and OMP10 groups with the controls. The maximum strength and rigidity of the femur did not differ in the experimental groups in comparison with the controls. The OMP300 group had a statistically lower serum Ca++ concentration than that of the controls (p = 0.049), but the other groups did not show any difference in relation to the controls. CONCLUSION: Daily intake of 300 µmoL/kg/day of omeprazole decreased the BMD of the femur, but without changes to the rigidity and strength of the femur in adult rats.

OBJETIVOS: Estudos epidemiológicos mostram uma relação entre o uso em longo prazo de inibidores de bomba de prótons e o metabolismo ósseo, porém essa relação ainda não está estabelecida. O objetivo deste estudo foi analisar as propriedade mecânicas e a densidade mineral óssea (DMO) de ratos submetidos ao uso de omeprazol em longo prazo. MÉTODOS: Cinquenta ratos Wistar, entre 200 e 240 g, foram divididos igualmente em cinco grupos: OMP300 (ingestão de omeprazol na dose de 300 µmoL/Kg/dia), OMP200 (200 µmoL/Kg/dia), OMP40 (40 µmoL/Kg/dia), OMP10 (10 µmoL/Kg/dia) e Cont (grupo controle; ingestão do veículo de diluição). A administração das soluções ocorreu durante 90 dias seguidos. Após a eutanásia, foram analisadas a DMO, as propriedades mecânicas dos fêmures dissecados e a dosagem de Ca++ sérico. RESULTADOS: A DMO do grupo OMP300 foi menor do que a do Cont (p = 0,006). Não houve diferença na comparação entre os grupos OMP200, OMP40 e OMP10 em relação ao Cont. A força máxima e rigidez do fêmur não foram diferentes nos grupos experimentais quando comparados ao Cont. O grupo OMP300 teve concentrações séricas de Ca++ estatisticamente menores do que o grupo Cont (p = 0,049) sem diferença entre os demais grupos em relação ao Cont. CONCLUSÃO: A ingestão diária de 300 µmoL/Kg/dia de omeprazol diminuiu a DMO do fêmur, porém sem alterações na rigidez e na força do fêmur de ratos adultos.