ABSTRACT
Most attempts to measure forces developed by the human hand have been implemented by placing force sensors on the object of interaction. Other researchers have placed sensors just on the subject's fingertips. In this paper, a system is described that measures forces over the entire hand using thin-film sensors and associated electronics. This system was developed by the authors and is able to obtain force readings from up to 60 thin-film sensors at rates of up to 400 samples/s per sensor. The sensors can be placed anywhere on the palm and/or fingers of the hand. The sensor readings, together with a video stream containing information about hand posture, are logged into a portable computer using a multiplexer, analogue-to-digital converter and software developed for the purpose. The system has been successfully used to measure forces involved in a range of everyday tasks such as driving a vehicle, lifting saucepans and hitting a golf ball. In the latter case, results are compared with those from an instrumented golf club. Future applications include the assessment of hand strength following disease, trauma or surgery, and to enable quantitative ergonomic investigations.
Subject(s)
Diagnosis, Computer-Assisted/instrumentation , Hand Strength/physiology , Hand/physiology , Monitoring, Ambulatory/instrumentation , Muscle Contraction/physiology , Physical Examination/instrumentation , Transducers , Activities of Daily Living , Diagnosis, Computer-Assisted/methods , Electric Impedance , Equipment Design , Equipment Failure Analysis , Golf/physiology , Humans , Male , Monitoring, Ambulatory/methods , Physical Examination/methods , Stress, MechanicalABSTRACT
The mechanisms by which nerve growth factor (NGF) induces thermal hyperalgesia and neutrophil accumulation have been investigated in the rat. Thermal nociceptive thresholds in rat hind paw were measured as the time taken for paw withdrawal from a heat source and neutrophil accumulation was measured in hind paw and dorsal skin samples using a myeloperoxidase assay. NGF (23-80 pmol intraplantar (i.pl.) injection) induced a significant (P < 0.05, n = 6-16) thermal hyperalgesia at 5 h after injection and significant neutrophil accumulation (P < 0.05, n = 6) was observed with NGF (40 pmol). In dorsal skin, where multiple samples can be assessed, intradermal (i.d.) NGF was 10-30 times less potent than interleukin-1beta in inducing neutrophil accumulation. The 5-lipoxygenase inhibitor ZM230487 (10 nmol co-injected with NGF) significantly attenuated neutrophil accumulation and hyperalgesia induced by NGF; unlike the histamine and 5-hydroxytryptamine antagonists (mepyramine and methysergide) which were without effect at the times measured. Furthermore, depletion of circulating neutrophils (using a rabbit anti-rat neutrophil antibody) abolished NGF induced hyperalgesia. These results indicate that neutrophils, which accumulate in response to a 5-lipoxygenase product, play a crucial role in NGF-induced hyperalgesia.
