Age-specific comparisons in the rate of force development of toe pressure strength and its association with the timed up and go test.

PURPOSE: It has recently been recommended that Rate of Force Development (RFD) be evaluated in addition to maximal muscle strength. There are no studies on RFD of toe pressure strength, and its importance in older adults and the extent to which it is associated with aging needs to be clarified. This study purpose was to examine the association between the RFD of toe pressure strength and timed up and go test (TUG) in an age-specific study. METHODS: This study is a cross-sectional study. Participants in the study included 159 younger adults (26.3 ± 13.1 years, 52% male) and 88 older adults (75.0 ± 6.2 years, 26% male). The RFD of toe pressure strength was determined from the force-time curve obtained during the toe pressure strength assessment, and the ability to exert maximum muscle force in the shortest possible time was assessed. Regression analysis was performed for each group to test the association between RFD of toe pressure strength and TUG by age. RESULTS: Younger adults showed no association between TUG and RFD of toe pressure strength, and significant association between TUG and RFD of toe pressure strength was found only in the older adults (standard regression coefficient = - 0.19, p = 0.048). CONCLUSION: This study showed a significant association between TUG and RFD of toe pressure strength in older adults. These findings show that RFD is one of the functions that should be assessed, particularly in older adults. Furthermore, it was suggested that approaching RFD could improve gait, standing, and sitting movements.

Porphyrins in urine after administration of 5-aminolevulinic acid as a potential tumor marker.

BACKGROUND: Tumor markers are commonly used for cancer screening and as indicators of therapeutic effects. Certain types of tumor have been known to produce a variety of porphyrins after 5-aminolevulinic acid (ALA) administration. In this study, porphyrins in tumor-bearing mouse urine were analyzed after oral administration of ALA in order to identify new tumor markers excreted in the urine. METHODS: Porphyrin concentrations in the urine of tumor-bearing mice were measured after administration of 1.0mg of ALA (approximately 50mgkg(-1)). RESULTS: Porphyrin concentrations in the urine of tumor-bearing mice increased after administration of ALA. HPLC analysis of the urine revealed the existence of uroporphyrin (UP) and coproporphyrin (CP) in the urine of ALA-treated tumor-bearing mice. Furthermore, at 3h after ALA administration, UP concentrations in the urine of tumor-bearing mice significantly increased compared to those in the urine of normal mice. CONCLUSION: These results suggest that UP as a precursor of heme detected in the urine of tumor-bearing mice after ALA administration is a potential marker of tumor development.