Age-related selection bias in Parkinson's disease research: are we recruiting the right participants?

Objective: To describe, and explore heterogeneity in, age at onset/diagnosis in Parkinson's disease (PD) and compare mean age at onset/diagnosis in incidence studies with that in general PD research studies.

Methods: We systematically reviewed studies of PD incidence. We meta-analysed mean age at onset/diagnosis and age-stratum-specific incidence rates.

Potential fields in vascular smooth muscle generated by transmitter release from sympathetic varicosities.

A quantitative model is provided of how current flow occurs in the media of blood vessels upon the release of transmitter from autonomic varicosities onto ionotropic receptors located on smooth muscle cells at the adventitial surface of the vessel. In particular, the extent to which potential generated in cells at the adventitial surface (AS) conducts through to cells at the intimal surface (IS) is investigated. Experimental tests of the model have been made for the case of the rat tail artery.

Methods for grouping shapes of synaptic currents recorded from sets of synapses.

Synaptic currents due to transmitter release at sets of synapses, such as those formed by a single nerve terminal on adjacent smooth muscle cells or a nerve terminal on a dendrite, possess different amplitudes and time courses, that is different shapes. It is possible that different shape groupings exist that may be each associated with a particular synapse in the set recorded from. Two methods, involving the distance between two synaptic currents, namely multidimensional scaling and hierarchical clustering, were used to suggest possible groupings.

Quantal currents and potential in the three-dimensional anisotropic bidomain model of smooth muscle.

The potential generated in the smooth muscle of the vas deferens on release of a quantum of transmitter from a varicosity was analyzed using a three-dimensional bidomain continuum model. Current was injected at the origin of the bidomain; this current had the temporal characteristics of the junctional current. The membrane potential, intracellular potential, and extracellular potential, as well as the extracellular current, were then calculated throughout the bidomain at different times.

The effects of submaximal endurance exercise upon LH pulsatility.

The acute effects of submaximal endurance exercise (three consecutive 20-min runs on a treadmill at 50, 60 and 70% of the subjects' maximum oxygen uptake) upon the pulsatile release of LH were compared with those accompanying leisurely strolling for a similar period in seven normally menstruating young women. All trials were conducted during the early to mid-luteal phase, as determined by body temperature patterns, ultrasonic scans of the ovaries, detection of the LH surge in first morning urine specimens, and serial measurements of plasma progesterone. Blood was sampled every 10 min via an indwelling cannula for 8 h before and 12 h after exercise and serum LH measured by radioimmunoassay.