Olfaction in Parkin single and compound heterozygotes in a cohort of young onset Parkinson's disease patients.

BACKGROUND: Parkin related Parkinson's disease (PD) is differentiated from idiopathic PD by absent or sparse Lewy bodies, and preserved olfaction. The significance of single Parkin mutations in the pathogenesis of PD is debated. OBJECTIVES: To assess olfaction results according to Parkin mutation status. To compare the prevalence of Parkin single heterozygous mutations in patients diagnosed with PD to the rate in healthy controls in order to establish whether these single mutations could be a risk factor for developing PD. METHODS: Parkin gene mutation testing was performed in young onset PD (diagnosed <50 years old) to identify three groups: Parkin homozygous or compound heterozygote mutation carriers, Parkin single heterozygote mutation carriers, and non-carriers of Parkin mutations. Olfaction was tested using the 40-item British version of the University of Pennsylvania smell identification test (UPSIT). RESULTS: Of 344 young onset PD cases tested, 8 (2.3%) were Parkin compound heterozygotes and 13 (3.8%) were Parkin single heterozygotes. Olfaction results were available in 282 cases (eight compound heterozygotes, nine single heterozygotes, and 265 non-carriers). In Parkin compound heterozygotes, the median UPSIT score was 33, interquartile range (IQR) 28.5-36.5, which was significantly better than in single Parkin heterozygotes (median 19, IQR 18-28) and non-carriers (median score 22, IQR 16-28) (ANOVA P < 0.001). These differences persisted after adjusting for age, disease duration, gender, and smoking (P < 0.001). There was no significant difference in UPSIT scores between single heterozygotes and non-carriers (P = 0.90). CONCLUSIONS: Patients with Parkin compound heterozygous mutations have relatively preserved olfaction compared to Parkin single heterozygotes and non-carriers. The prevalence of Parkin single heterozygosity is similar to the 3.7% rate reported in healthy controls.

Accuracy of subjective and objective handwriting assessment for differentiating Parkinson's disease from tremulous subjects without evidence of dopaminergic deficits (SWEDDs): an FP-CIT-validated study.

Handwriting examinations are commonly performed in the analysis of tremor and Parkinson's disease (PD). We analyzed the accuracy of subjective and objective assessment of handwriting samples for distinguishing 27 PD cases, 22 with tremulous PD, and five with akinetic-rigid PD, from 39 movement-disorder patients with normal presynaptic dopamine imaging (subjects without evidence of dopamine deficiency or SWEDDs; 31 with dystonic tremor (DT), six indeterminate tremor syndrome, one essential tremor, one vascular parkinsonism). All handwriting analysis was performed blind to clinical details. Subjective classification was made as: (1) micrographia, (2) normal, or (3) macrographia. In addition, a range of objective metrices were measured on standardized handwriting specimens. Subjective assessments found micrographia more frequently in PD than SWEDDs (p = 0.0352) and in akinetic-rigid than tremulous PD (p = 0.0259). Macrographia was predominantly seen in patients with dystonic tremor and not other diagnoses (p = 0.007). Micrographia had a mean sensitivity of 55 % and specificity of 84 % for distinguishing PD from SWEDDs and mean sensitivity of 90 % and specificity of 55 % for distinguishing akinetic-rigid PD from tremulous PD. Macrographia had a sensitivity of 26 % and specificity of 96 % for distinguishing DT from all other diagnoses. The best of the objective metrices increased sensitivity for the distinction of SWEDDs from PD with a reduction in specificity. We conclude that micrographia is more indicative of PD than SWEDDs and more characteristic of akinetic-rigid than tremulous PD. In addition, macrographia strongly suggests a diagnosis of dystonic tremor.

Familial adult onset of Krabbe's disease resembling hereditary spastic paraplegia with normal neuroimaging.

Krabbe's disease (globoid cell leucodystrophy) is a disorder involving the white matter of the peripheral and central nervous systems. Mutations in the gene for the lysosomal enzyme galactocerebrosidase (GALC) result in low enzymatic activity and decreased ability to degrade galactolipids found in myelin. The disease is classically of infantile onset, but adult onset cases have been reported. Magnetic resonance imaging (MRI) of the brain shows characteristic abnormalities. A unique family with Krabbe's disease is described, with proven GALC deficiency but normal MRI. A neurological phenotype is present in heterozygotes and the family shows the extent of homozygotic phenotypic diversity that can be seen in this disorder.

Acute transverse myelitis and Guillain-Barré overlap syndrome with serological evidence for mumps viraemia.

Both acute transverse myelitis (ATM) and Guillain-Barré syndrome (GBS) occur as rare associations with mumps viraemia but to our knowledge, concurrent ATM and GBS related to mumps has only been reported once previously. We describe the case of a young woman presenting with confusion and collapse 2 weeks after a flu-like illness. An initial diagnosis of transverse myelitis was made on the basis of the clinical findings and radiological evidence of a swollen spinal cord with uniform high signal change on T2 weighted MRI. The patient was treated with intravenous methylprednisolone without significant recovery. The diagnosis was later revised to include GBS on the basis of worsening facial diplegia in the setting of a flaccid tetraparesis, and neurophysiological evidence of a sensorimotor axonal polyradiculoneuropathy. Acute mumps viraemia was confirmed on serological grounds. The patient made an improvement in ventilatory capacity with intravenous immunoglobulin treatment.

Phosphorylation of neurofilament heavy chain side-arms by stress activated protein kinase-1b/Jun N-terminal kinase-3.

Neurofilaments comprise three subunit proteins; neurofilament light, middle and heavy chains (NF-L, NF-M and NF-H). The carboxy-terminal domains of NF-M and NF-H form side-arms that project from the filament and that of NF-H contains multiple repeats of the motif lys-ser-pro, the serines of which are targets for phosphorylation. The level of phosphorylation on the lys-ser-pro repeats varies topographically within the cell; in cell bodies and proximal axons, the side-arms are largely non-phosphorylated whereas in more distal regions of axons, the side-arms are heavily phosphorylated. Here we show that stress activated protein kinase 1b (SAPK1b), a major SAPK in neurones will phosphorylate NF-H side-arms both in vitro and in transfected cells. These studies suggest that SAPK1b targets multiple phosphorylation sites within NF-H side-arms. Additionally, we show that glutamate treatment induces activation of SAPK1b in primary cortical neurones and increased phosphorylation of NF-H in cell bodies. This suggests that glutamate causes increased NF-H phosphorylation at least in part by activation of stress activated protein kinases.

Cyclin-dependent kinase-5 (CDK5) and amyotrophic lateral sclerosis.

Cyclin-dependent kinase-5 (CDK5) is a serine-threonine protein kinase that has been implicated in a number of physiological processes in nerve and muscle cells, including neurogenesis, neuritic outgrowth, axonal transport of membrane-bound organelles and myogenesis. CDK5 has also been shown to phosphorylate the important cytoskeletal proteins, neurofilament and tau, both in vitro and in cells. The latter has prompted study into the potential role of CDK5 in the hyperphosphorylation of these proteins as part of the neuropathology seen in amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases. More recently, increasing evidence has suggested a role for CDK5 in cellular apoptosis. Apoptosis has been implicated as the final common pathway of cell death in a number of neurodegenerative diseases including ALS. This article sets out to review the physiological and pathological roles ascribed to CDK5 and the possible relevance thereof to the pathogenesis of ALS.

Cyclin dependent kinase-5 (CDK-5) phosphorylates neurofilament heavy (NF-H) chain to generate epitopes for antibodies that label neurofilament accumulations in amyotrophic lateral sclerosis (ALS) and is present in affected motor neurones in ALS.

1. Accumulations of phosphorylated neurofilaments are seen in affected motor neurones in amyotrophic lateral sclerosis (ALS). 2. The authors demonstrate that cyclin dependent kinase-5 (cdk-5) will induce cellular phosphorylation of neurofilament heavy chain side-arms to generate epitopes for several antibodies that label these neurofilament accumulations. 3. By creating recombinant neurofilament fragments of NF-H side-arm domains, the authors also map the epitopes for several of these antibodies. 4. Finally, the authors demonstrate that cdk-5 is also present in affected motor neurones in ALS. These studies implicate cdk-5 in the pathogenesis of ALS.

The genetics of Parkinson's disease and parkinsonian syndromes.

The finding of a mutation in the alpha-synuclein gene in a rare autosomal dominant form of idiopathic Parkinson's disease (IPD), has prompted increased interest in identifying genes that account for the more common sporadic form. A number of association studies have suggested that functional polymorphisms in genes that play a role in dopamine, drug and toxin metabolism may increase the relative risk of IPD. Unfortunately, patient numbers are often small, and the results have not been consistently reproduced. This article reviews the evidence from epidemiological, imaging and genetic studies to determine the role of genetic susceptibility in IPD and parkinsonian syndromes.

Cyclin-dependent kinase-5 is associated with lipofuscin in motor neurones in amyotrophic lateral sclerosis.

We have studied the distribution of cyclin dependent kinase-5 (cdk-5) within spinal cord in sporadic and two superoxide dismutase type 1 (SOD1) familial cases of amyotrophic lateral sclerosis (ALS). Although most neurofilament accumulations in ALS motor neurones did not appear to contain high levels of cdk-5, intense cdk-5 immunoreactivity was observed in perikarya of degenerating neurones in many ALS cases. Here, cdk-5 co-localised with lipofuscin. Co-localisation of cdk-5 with lipofuscin was also observed in some aged non-affected controls although this labelling was less intense than the ALS cases. The biogenesis of lipofuscin is believed to be linked to oxidative stress and oxidative stress and free radical damage have been suggested to be part of the pathogenic process of ALS, possibly involving apoptotic mechanisms. cdk-5 has recently been associated with apoptosis. These observations suggest a role for cdk-5 in the pathogenesis of ALS.

Phosphorylation of neurofilament heavy-chain side-arm fragments by cyclin-dependent kinase-5 and glycogen synthase kinase-3alpha in transfected cells.

The side-arm domain of neurofilament heavy-chain (NF-H) is heavily phosphorylated in axons. Much of this phosphate is located within a multiphosphorylation repeat (MPR) domain situated toward the carboxy terminus of the molecule. The MPR domain contains the repeat motif KSP of which there are two broad categories, KSPXX and KSPXK. In mouse NF-H, the KSPXK repeats are situated toward the latter part of the MPR domain. We have expressed in mammalian cells fragments of mouse NF-H side-arm containing all of the MPR domain, the latter part of the MPR domain containing the KSPXK repeats, and the complementary amino-terminal part of the MPR domain, which contains the KSPXX repeats. By cotransfecting these fragments with the neurofilament kinases cyclin-dependent kinase-5 (cdk-5)/p35 and glycogen synthase kinase-3alpha (GSK-3alpha), we show that cdk-5 induces cellular phosphorylation of the KSPXK-containing fragment of NF-H. Using the transfected fragments, we also map the epitopes for several commonly utilised NF-H monoclonal antibodies and describe the effects that phosphorylation by cdk-5 and GSK-3alpha have on their reactivities.

Cellular phosphorylation of neurofilament heavy-chain by cyclin-dependent kinase-5 masks the epitope for monoclonal antibody N52.

N52 is a widely used monoclonal antibody reported to recognise both phosphorylated and non-phosphorylated forms of neurofilament (NF)-H. N52 is therefore classified as a phosphorylation-independent-type antibody. N52 is strongly reactive with NF-H in COS cells transfected with NF-H alone but co-transfection of NF-H with the neurofilament kinase cdk-5 and one of its activators p35, induced phosphorylation of NF-H that abolished this reactivity. Treatment of the cdk-5 phosphorylated NF-H with alkaline phosphatase so as to remove phosphate restored N52 reactivity. A fragment of NF-H containing the consensus cdk-5 sites was reactive with N52 but following co-transfection with cdk-5/p35 a slower migrating fragment species generated by cdk-5 was not labelled by N52. These results demonstrate that N52 is not a truly phosphorylation-independent-type NF-H antibody and suggest that the N52 epitope contains sites targeted for phosphorylation by cdk-5.

Sequence-selective, pH-dependent binding to DNA of benzophenanthridine alkaloids.

The sequence selectivity associated with binding to DNA of three alkaloids belonging to the benzophenanthridine family has been analysed by DNase I footprinting, and the results were compared with those obtained from an analysis of the behaviour of the standard intercalator, ethidium bromide. Like the ethidium, the benzophenanthridine compounds appear to bind best to regions of mixed nucleotide sequence, especially those containing alternating purines and pyrimidines, although there are some notable differences in behaviour. There is also a marked lack of binding to sequences such as (AT)n, where n greater than or equal to 3. The binding to DNA of the benzophenanthridines is specifically related to the hydrogen ion concentration of the medium, in that the DNase I footprints are considerably enhanced when the reaction is performed at a pH below 7.0. We discuss these results in terms of a greater preponderance of the intercalating species being present at lower pH.