Patients with X-linked hypophosphatemia (XLH) and the hyp-mouse, a model of XLH characterized by a deletion in the Phex gene, manifest hypophosphatemia, renal phosphate wasting, and rickets/osteomalacia. Cloning of the PHEX/Phex gene and mutations in affected patients and hyp-mice established that alterations in PHEX/Phex expression underlie XLH. Although PHEX/Phex expression occurs primarily in osteoblast lineage cells, transgenic Phex expression in hyp-mouse osteoblasts fails to rescue the phenotype, suggesting that Phex expression at other sites underlies XLH. To establish whether abnormal Phex in osteoblasts and/or osteocytes alone generates the HYP phenotype, we created mice with a global Phex knockout (Cre-Phex Δflox/y mice) and conditional osteocalcin-promoted (OC-promoted) Phex inactivation in osteoblasts and osteocytes (OC-Cre-Phex Δflox/y ). Serum phosphorus levels in Cre-Phex Δflox/y , OC-Cre-Phex Δflox/y , and hyp-mice were lower than those in normal mice. Kidney cell membrane phosphate transport in Cre-Phex Δflox/y , OC-Cre-Phex Δflox/y , and hypmice was likewise reduced compared with that in normal mice. Abnormal renal phosphate transport in CrePhex Δflox/y and OC-Cre-Phex Δflox/y mice was associated with increased bone production and serum FGF-23 levels and decreased kidney membrane type IIa sodium phosphate cotransporter protein, as was the case in hyp-mice. In addition, Cre-Phex Δflox/y , OC-Cre-Phex Δflox/y , and hyp-mice manifested comparable osteomalacia. These data provide evidence that aberrant Phex function in osteoblasts and/or osteocytes alone is sufficient to underlie the hyp-mouse phenotype.

Abstract-In this study, in order to realize an assist of independent life for the elderly or people in need of care and relieve a physical burden for care worker, an active support splint driven by pneumatic soft actuator (ASSIST) has been developed. ASSIST consists of a plastic interface with the palm and arm and two rotary-type soft actuators put in both sides of appliance. In this paper, the fundamental characteristics of ASSIST is described, and then the effectiveness of this splint is experimentally discussed. Finally, the operation of ASSIST based on a human intention is described.

The purpose of this study is to develop a soft-material power-assist glove for hand grasping in daily life by older or disabled persons. Such a glove must be compact, lightweight, and flexible. The glove we developed consists of rubber and cloth, and is user-friendly. This paper describes the types of rubber muscle and the soft power-assist glove, together with control based on human intent and the effectiveness of our proposal.

In the future, when the average age of the members of society becomes advanced, an innovative technology to assist the activities of daily living of elderly and disabled people and to assist in the heavy work in nursing will be desired. To develop such a technology, an actuator that is safe and user-friendly is required. It should be small, lightweight, and sufficiently soft. Such an actuator is available in artificial muscle made of pneumatic rubber. We have developed some types of pneumatic rubber artificial muscles and applied them to wearable power assist devices. A wearable power assist device is fitted to the human body to assist the power of muscles that support the activities of daily living, rehabilitation, training, and so on. In this paper, some types of pneumatic rubber artificial muscles developed and manufactured in our laboratory are presented. Furthermore, two kinds of wearable power assist devices driven by the rubber artificial muscles are described. Finally, some evaluations clarify the effectiveness of pneumatic rubber artificial muscle for innovative human assistance technologies.

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