ANALYSIS OF THE PERFORMANCE OF ABOVE-KNEE AMPUTEES IN CLIMBING STAIRS

INTRODUCTION Although a large investment has been already made in the study of the walking performance of amputees a greater understanding of the capacities of these subjects is still needed. In this context we undertook the present study in order to analyse the performance of above-knee amputees (AKA) in tasks related to locomotion. We studied two groups of individuals, one of able bodied (AB) subjects and a AKA group, perform ing two different tasks, namely, level ground (LG) walking and climbing stairs (CS). METHODS For each individual and for each task three trials were recorded. The CS task corresponded to the. climbing of a staircase of three 16 cm in height steps. The performances were normalised by comparing a complete LG walking cycle and the climbing CS from the first to the second step. These performances were filmed by two video cameras, one located at the side and another at the back of the track. A thirteen segments body model is used to calculate the center of mass (CM). The percent values of the CM co-ordinates relative to the subject's height is calculated along the vertical (Z axis) , the horizontal antero-posterior (Y axis) and the (axis X) normal to the previous ones using a method developed by Enseberg et al. (1992). The sagittal and lateral inclinations of the trunk and the sagittal rotation of the knee are also computed. RESULTS AND DISCUSSIONS The CM for the AKA group performing the LG and CS tasks is located at a lower level (Z), further to the back (Y) and, generally, on the side of the prosthesis . (X) as compared with its location for the AB group performing the same tasks. These results agree with those obtained Engsberg et al. (1992) for the LG task. The CM location along the Z axis is determined fundamentally by the forward flexion of the trunk and, for both groups of subjects, is lower for the CS task than for the LG tasks as a result of the need to place this center on the vertical of the propulsive limb. For both tasks, the CM location along the Y axis is similar for the two groups and only slightly more posterior for the AKA group in result of the larger backwards rotation of the arm opposite to the prosthesis. The CM location along the X is, for the AKA group, always opposite to the prosthetic side as a result of the trunk compensating inclination in that direction. For the AB group, the CM oscillates naturally from side to side of the body sagittal plane. CONCLUSIONS We may conclude from these results that the two tasks correspond to significantly different performances and that the differences are more profound for the AKA group. The use of a staircase to test the performance of AKA subjects is clinically relevant as it brings up some of the most serious problems associated with the quality of adaptation of the prosthesis to the patient. REFERENCES Engsberg, J., K. Tedford & J. Harder (1992). Center of mass location and segment angular orientation of below-knee amputee and able-bodied children during walking. Arch. Phys. Med. Reahabili, 73, 1163-1168

ACE as a Mechanosensor to Shear Stress Influences the Control of Its Own Regulation via Phosphorylation of Cytoplasmic Ser1270

Objectives: We tested whether angiotensin converting enzyme (ACE) and phosphorylation of Ser(1270) are involved in shear-stress (SS)-induced downregulation of the enzyme. Methods and Results: Western blotting analysis showed that SS (18 h, 15 dyn/cm(2)) decreases ACE expression and phosphorylation as well as p-JNK inhibition in human primary endothelial cells (EC). CHO cells expressing wild-type ACE (wt-ACE) also displayed SS-induced decrease in ACE and p-JNK. Moreover, SS decreased ACE promoter activity in wt-ACE, but had no effect in wild type CHO or CHO expressing ACE without either the extra-or the intracellular domains, and decreased less in CHO expressing a mutated ACE at Ser(1270) compared to wt-ACE (13 vs. 40%, respectively). The JNK inhibitor (SP600125, 18 h), in absence of SS, also decreased ACE promoter activity in wt-ACE. Finally, SS-induced inhibition of ACE expression and phosphorylation in EC was counteracted by simultaneous exposure to an ACE inhibitor. Conclusions: ACE displays a key role on its own downregulation in response to SS. This response requires both the extra- and the intracellular domains and ACE Ser(1270), consistent with the idea that the extracellular domain behaves as a mechanosensor while the cytoplasmic domain elicits the downstream intracellular signaling by phosphorylation on Ser(1270).Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[01/00009-0]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[03/14115-2]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[06/52053-7]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[480120/2007-2

The renin-angiotensin system is modulated by swimming training depending on the age of spontaneously hypertensive rats

Aim: To investigate the effects of swimming training on the renin-angiotensin system (RAS) during the development of hypertensive disease. Main methods: Male spontaneously hypertensive rats (SHR) were randomized into: sedentary young (SY), trained young (TV), sedentary adult (SA), and trained adult (TA) groups. Swimming was performed 5 times/wk/8wks. Key findings: Trained young and adult rats showed both decreased systolic and mean blood pressure, and bradycardia after the training protocol. The left ventricular hypertrophy (LVH) was observed only in the TA group (12.7%), but there was no increase on the collagen volume fraction. Regarding the components of the RAS, TV showed lower activity and gene expression of angiotensinogen (AGT) compared to SY. The TA group showed lower activity of circulatory RAS components, such as decreased serum ACE activity and plasma renin activity compared to SA. However, depending on the age, although there were marked differences in the modulation of the RAS by training, both trained groups showed a reduction in circulating angiotensin II levels which may explain the lower blood pressure in both groups after swimming training. Significance: Swimming training regulates the RAS differently in adult and young SHR rats. Decreased local cardiac RAS may have prevented the LVH exercise-induced in the TV group. Both groups decreased serum angiotensin II content, which may, at least in part, contribute to the lowering blood pressure effect of exercise training. (C) 2011 Elsevier Inc. All rights reserved