The impact of drug-induced dyskinesias on rapid alternating movements in patients with Parkinson's disease

We investigated the likelihood that hypokinesia/bradykinesia coexist with druginduced dyskinesias (DID) in patients with Parkinson's disease (PD). The influence of dyskinesias on rapid alternating movements (RAM) was investigated in ten dyskinetic patients (DPD). Their motor performance was compared to that of ten age/gendermatched non-dyskinetic patients (NDPD) and ten healthy control subjects. Whole-body magnitude (WBM) and fast pronation-supination at the wrist were recorded using 6- degrees of freedom magnetic motion tracker and forearm rotational sensors, respectively. Subjects were asked to pronate-supinate their dominant hand for 10s. Pre- and postmeasures were taken in a neutral position for 20s. RANGE (measure of hypokinesia), DURATION (measure of bradykinesia). VELOCITY (measure of bradykinesia) and IRREGULARITY (measure of fluctuations in movement amplitude) were used to assess RAM performance. Results showed that DPD patients had greater WBM than NDPD and control groups during rest and RAM performance. There were no differences in performance between NDPD and DPD groups for RANGE, DURATION and VELOCITY, despite significant longer disease duration for the DPD group (DPD = 15.5 ± 6.2 years versus NDPD = 6.6 ± 2.6 years). However, both the NDPD and DPD groups showed lower RANGE, longer DURATION, and reduced VELOCITY compared to controls,, suggesting the presence of bradykinesia and hypokinesia. In the case of IRREGULARITY, DPD patients showed clear fluctuations in movement amplitude compared to the NDPD and control groups. However, the lack of correlation between WBM and IRREGULARITY within the DPD group (Spearman's rank order, Rho - 0.31, p > 0.05), suggests that DID was not the primary cause of the fluctuating movementamplitude observed in that group. In conclusion, these findings suggest that DID may coexists with bradykinesia and hypokinesia, but that they are not inevitably accompanied with worsening motor performance.

Simultaneous extraction of order parameters and orientational distribution fuctions from 31[superscript]P NMR spectra of magnetically partially oriented phospholipid bilayers

Order parameter profiles extracted from the NMR spectra of model membranes are a valuable source of information about their structure and molecular motions. To al1alyze powder spectra the de-Pake-ing (numerical deconvolution) ~echnique can be used, but it assumes a random (spherical) dist.ribution of orientations in the sample. Multilamellar vesicles are known to deform and orient in the strong magnetic fields of NMR magnets, producing non-spherical orientation distributions. A recently developed technique for simultaneously extracting the anisotropies of the system as well as the orientation distributions is applied to the analysis of partially magnetically oriented 31p NMR spectra of phospholipids. A mixture of synthetic lipids, POPE and POPG, is analyzed to measure distortion of multilamellar vesicles in a magnetic field. In the analysis three models describing the shape of the distorted vesicles are examined. Ellipsoids of rotation with a semiaxis ratio of about 1.14 are found to provide a good approximation of the shape of the distorted vesicles. This is in reasonable agreement with published experimental work. All three models yield clearly non-spherical orientational distributions, as well as a precise measure of the anisotropy of the chemical shift. Noise in the experimental data prevented the analysis from concluding which of the three models is the best approximation. A discretization scheme for finding stability in the algorithm is outlined