Objective clinical analyses are required to evaluate balance control performance. To this outcome, it is relevant to study experimental protocols and to develop devices that can provide reliable information about the ability of a subject to maintain balance. Whereas most of the applications available in the literature and on the market involve shifting and tilting of the base of support, the system presented in this paper is based on the direct application of an impulsive (short-lasting) force by means of an electromechanical device (named automatic perturbator). The control of such stimulation is rather complex since it requires high dynamics and accuracy. Moreover, the occurrence of several non-linearities, mainly related to the human–machine interaction, signals the necessity for robust control in order to achieve the essential repeatability and reliability. A linear electric motor, in combination with Model Predictive Control, was used to develop an automatic perturbator prototype. A test bench, supported by model simulations, was developed to test the architecture of the perturbation device. The performance of the control logic has been optimized by iterative tuning of the controller parameters, and the resulting behavior of the automatic perturbator is presented.

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SummaryHeat-shock protein (HSP)-65 of mycobacterial origin has been implicated in the mediation of atherosclerosis by immune mechanisms. Any role of HSP-65 in mediating restenosis is however not clear. We determined the anti-HSP-65 antibodies in 28 patients, 25 male and 3 female, aged 35 to 78 years, with coronary artery disease (CAD) and undergoing percutaneous transluminal coronary angioplasty (PTCA). Of the 28 patients, 12 suffered restenosis five to seven months later.The serum levels of antibody were measured at baseline, immediately after PTCA, before discharge from the hospital, and at 6 weeks, 3 and 6 months after the performance of PTCA. The antibody levels were expressed in OD U/log titre, as explained in the text, and termed estimated OD or EOD. The control group consisted of 29 healthy volunteers, 16 male and 13 female, aged 24 to 59 years. The mean Eod of the patients at baseline was higher than that of the controls (0.60 ± 0.12, SD; 95% Cl 0.56-0.64 compared with 0.53 ± 0.13; 0.48-0.58; p < 0.01). There was no correlation between age and EOD of patients, controls or both taken together, ruling out the influence of age on the EOD changes in the given age range. The mean antibody levels of the patients with CAD were similar whether or not they suffered subsequent restenosis (0.61 ± 0.15; 0.53-0.69 in the patency group, and 0.60 ± 0.10; 0.54-0.66 in the restenosis group). However, the patients who did not develop restenosis had a drop in their antibody levels immediately after PTCA (0.51 ± 0.14; 0.48-0.55; 2-tailed p = 0.029), and at discharge from the hospital (0.52 ± 0.15; 0.44-0.60; p = 0.036) as compared with the baseline. This decrease of antibodies was not observed in the restenosis group. Furthermore, the anti-HSP-65 antibody levels remained slightly low throughout the 6-month follow-up in the patients with patent coronaries as compared with patients who reste-nosed, but the decrease was statistically not significant at 5% level at any stage. Besides the anti-HSP-65 antibodies, the levels of anticardio-lipin (ACL) antibody were also measured in all the patients. The levels of the ACL antibody were found to be within the normal range before and at all stages after PTCA, ruling out the PTCA-associated change in the anti-HSP-65 antibody as a non-specific occurrence. Thus, a drop in the level of antibody against HSP-65 after PTCA seemed to be associated with a favourable outcome, and may serve as a useful prognostic marker of coronary angioplasty

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Intermittent Pneumatic Compression (IPC) devices can be used to analyze the mechanisms underlying several vascular phenomena, such as hyperaemia. Commercial devices have limited dynamics and do not allow the delivery of customizable compressive pressure patterns, making difficult the analysis of such phenomena, which may require the application of long stimulations with low amplitude as well as fast compressions with higher pressure level. To overcome these issues, a novel pneumo-tronic device aimed to the investigation of the physiological effects induced by limb compressions has been conceived and is presented in this work. The design requirements of the system, capable of delivering customizable compressive patterns in the range 0-200 mmHg, are outlined. The final prototype architecture is described, and a mathematical model of the entire system, also including the interaction between the device and the limb tissues, is proposed. The performance of the device has been evaluated in several conditions by means of simulations, whose results have been compared to the data collected from experimental trials in order to validate the model. The outcomes of both experimentation and simulation trials proved the effectiveness of the solution proposed. A possible employment of this device for the investigation of the rapid compression-induced hyperaemia is presented. Other potential applications concern the wide range of intermittent-pneumatic compression treatments.

Abstract. In recent years, exoskeletons are increasingly spreading into the industrial manufacturing sector to improve productivity and to reduce the incidence of work-related musculoskeletal diseases. The aim of this paper is to present a 2 degrees of freedom (DoF) passive upper-limb exoskeleton, consisting of two McKibben pneumatic artificial muscles (PAMs), and used for assisting workers during activities that require them to keep their hands in a sustained position over the head for a long time. Simulations are performed to test two different commercial PAMs and two different designs of the transmission system used to convey the traction force exerted by the pneumatic muscles to the limb; then the results are discussed. A preliminary assembly of the exoskeleton is also presented. The study confirms that PAMs can be used to realize a passive upper-limb exoskeleton for industrial application and that appropriate working space can be obtained with an accurate design of the transmission system.

ObjectiveCommercial devices for pneumatic compressive treatment of the limbs generally provide predefined stereotyped compressive profiles. The possibility to deliver compressive stimuli with a customizable pressure profile would be useful to differently probe the vascular reactivity to muscle compression (MC) and improve the understanding of MC-induced hyperemia. Aim of this study was the realization of a novel pneumatic system capable of generating adjustable and stable compressive conditions, preceding and following a "standard" MC stimulus Approach A custom-made pneumatic system specifically built to this purpose is tested and characterized in 10 subjects.Three different compressive patterns were delivered to the leg: 1) a constant level: 50 mmHg for 50 s; 2) MC: 200 mmHg for 1 s; 3) a complex profile: 20 mmHg for 50 s, 200 mmHg for 1 s, 50 mmHg for 50 s. Main resultsThe implemented system allowed to deliver graded compressions to the limb characterized by fast transitions (0 to 200 mmHg in 0.5 ± 0.07 s) and stable plateau levels (50.4 ± 0.5 mmHg). SignificanceA new, low-cost, pneumatic prototype has been presented and tested in the present study allowing to deliver compressive stimuli with pre-and post-compressions of adjustable level. This device has been conceived for research purposes and may find application in therapeutic compressive treatments.