These volume/function relationships presumably reflect the effects of subcortical axonal and myelin loss on the neural networks that subserve cognition. If serial MRI volume estimations can index accumulating cognitive deficits, this simple technique may be useful in therapeutic trials.

Vital capacity (VC) and maximum mouth pressures are often used to monitor respiratory function in motor neuron disease (MND), but require the use of a mouthpiece. Sniff nasal inspiratory pressure (SNIP) is a simple and reliable means of measuring inspiratory muscle strength; it does not involve the use of a mouthpiece and might therefore be better than VC or mouth pressures for assessing patients with bulbar disease.SNIP, maximum inspiratory (MIP) and expiratory mouth pressure (MEP), VC and arterial carbon dioxide tension (Pa,CO 2 ) were measured in 59 consecutive patients attending a specialist MND clinic. Thirty-one had bulbar involvement on clinical grounds.Both SNIP and VC were inversely related to Pa,CO 2 in nonbulbar patients only. Neither MIP nor MEP were related to Pa,CO 2 . The 10 patients with an elevated Pa,CO 2 (>6 kPa) had significantly lower SNIP and VC than normocapnic patients.Sniff nasal inspiratory pressure can be used to monitor respiratory function in motor neuron disease. It is quick and easy for patients to perform, but otherwise appears to offer little advantage over vital capacity measurement. Patients with bulbar disease are often poor at performing sniff nasal inspiratory pressure manoeuvres, possibly because of upper airway collapse or inability to close the mouth completely during the manoeuvre. Eur Respir J 2000; 15: 539±542.

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An optical CMOS heart rate sensor that processes the photoplethysmographic signal was designed and fabricated in Austriamicrosystems 0.35μm CMOS process. The sensor consists of photodiode, transimpedance amplifier, analogue bandpass filters, analogue-to-digital converters, digital signal processor, and a timing circuit that is used to modulate the external light-emitting diodes. The mixed-signal simulation has been carried out to validate the system design. With modulated green light source and integrated lock-in detection the sensor is capable of extracting clean photoplethysmographic signal when it is operated in reflectance mode. The heart rate output was compared with commercial devices and they show a good agreement. The chip-level integration enables a small foot print of the design and makes it suitable for the applications of ambulatory monitoring.