Carsten Buhmann

Plasma and CSF markers of oxidative stress are increased in Parkinson's disease and influenced by antiparkinsonian medication.

We determined systemic oxidative stress in Parkinsons disease (PD) patients, patients with other neurological diseases (OND) and healthy controls by measurement of in vitro lipoprotein oxidation and levels of hydro- and lipophilic antioxidants in plasma and cerebrospinal fluid (CSF). Additionally, we investigated the influence of levodopa (LD) and dopamine agonist therapy (DA) on the oxidative status in PD patients. We found increased oxidative stress, seen as higher levels of lipoprotein oxidation in plasma and CSF, decrease of plasma levels of protein sulfhydryl (SH) groups and lower CSF levels of alpha-tocopherol in PD patients compared to OND patients and controls. Levodopa treatment did not significantly change the plasma lipoprotein oxidation but LD monotherapy tended to result in an increase of autooxidation and in a decrease of plasma antioxidants with significance for ubiquinol-10. DA monotherapy was significantly associated with higher alpha-tocopherol levels. Patients with DA monotherapy or co-medication with DA showed a trend to lower lipoprotein oxidation. These data support the concept of oxidative stress as a factor in the pathogenesis of PD and might be an indicator of a potential prooxidative role of LD and a possible antioxidative effect of DA in PD treatment.

Activity parameters of subthalamic nucleus neurons selectively predict motor symptom severity in Parkinson's disease.

Parkinsons disease (PD) is a heterogeneous disorder that leads to variable expression of several different motor symptoms. While changes in firing rate, pattern, and oscillation of basal ganglia neurons have been observed in PD patients and experimental animals, there is limited evidence linking them to specific motor symptoms. Here we examined this relationship using extracellular recordings of subthalamic nucleus neurons from 19 PD patients undergoing surgery for deep brain stimulation. For each patient, ≥10 single units and/or multi-units were recorded in the OFF medication state. We correlated the proportion of neurons displaying different activities with preoperative Unified Parkinsons Disease Rating Scale subscores (OFF medication). The mean spectral power at sub-beta frequencies and percentage of units oscillating at beta frequencies were positively correlated with the axial and limb rigidity scores, respectively. The percentage of units oscillating at gamma frequency was negatively correlated with the bradykinesia scores. The mean intraburst rate was positively correlated with both bradykinesia and axial scores, while the related ratio of interspike intervals below/above 10 ms was positively correlated with these symptoms and limb rigidity. None of the activity parameters correlated with tremor. The grand average of all the significantly correlated subthalamic nucleus activities accounted for >60% of the variance of the combined bradykinetic-rigid and axial scores. Our results demonstrate that the occurrence of alterations in the rate and pattern of basal ganglia neurons could partly underlie the variability in parkinsonian phenotype.

Mapping preclinical compensation in Parkinson's disease: an imaging genomics approach.

Mutations in the Parkin (PARK2) and PINK1 gene (PARK 6) can cause recessively inherited Parkinsons disease (PD). The presence of a single Parkin or PINK1 mutation is associated with a dopaminergic nigrostriatal dysfunction and conveys an increased risk to develop PD throughout lifetime. Therefore neuroimaging of non‐manifesting individuals with a mutant Parkin or PINK1 allele opens up a window for the investigation of preclinical and very early phases of PD in vivo. Here we review how functional magnetic resonance imaging (fMRI) can be used to identify compensatory mechanisms that help to prevent development of overt disease. In two separate experiments, Parkin mutation carriers displayed stronger activation of rostral supplementary motor area (SMA) and right dorsal premotor cortex (PMd) during a simple motor sequence task and anterior cingulate motor area and left rostral PMd during internal movement selection as opposed to externally cued movements. The additional recruitment of the rostral SMA and right rostral PMd during the finger sequence task was also observed in a separate group of nonmanifesting mutation carriers with a single heterozygous PINK1 mutation. Because mutation carriers were not impaired at performing the task, the additional recruitment of motor cortical areas indicates a compensatory mechanism that effectively counteracts the nigrostriatal dysfunction. These first results warrant further studies that use these imaging genomics approach to tap into preclinical compensation of PD. Extensions of this line of research involve fMRI paradigms probing nonmotor brain functions. Additionally, the same fMRI paradigms should be applied to nonmanifesting mutation carriers in genes linked to autosomal dominant PD. This will help to determine how “generically” the human brain compensates for a preclinical dopaminergic dysfunction.

Effects of Mitoxantrone on Multiple Sclerosis Patients’ Lymphocyte Subpopulations and Production of Immunoglobulin, TNF-alpha and IL-10

We designed this longitudinal study to clarify the short- and long-term effects of mitoxantrone on the immune system in a subgroup of multiple sclerosis patients treated at our centre. After 14 days we found a highly significant sustained reduction of leucocytes, primarily affecting neutrophils and most lymphocyte subsets except for naive and activated T lymphocytes. The CD4/CD8 ratio and serum immmunoglobulin levels were not affected. Furthermore, whole blood-stimulated mononuclear cell IL-10 production showed a significant lower level 2 weeks treatment, whereas basal IL-10 as well as stimulated and basal TNF-α secretion showed no significant changes. Longitudinal data disclosed a persistent decrease of B lymphocytes, while secretion of immunoglobulins, IL-10, and TNF-α was not altered in the follow-up. In conclusion, we confirmed a selective short-term effect of mitoxantrone therapy on most lymphocyte subpopulations, but not on immunoglobulines or the pro- and anti-inflammatory cytokines TNF-α and IL-10, which do not serve as possible response markers.

Impaired sense of smell and color discrimination in monogenic and idiopathic Parkinson's disease†

Olfaction is typically impaired in idiopathic Parkinsons disease (IPD), but its role is uncertain in monogenic PD. Diminished color discrimination has been suggested as another early sign of dopaminergic dysfunction but not been systematically studied. Furthermore, it is unknown whether both deficits are linked. We examined 100 patients with IPD, 27 manifesting mutation carriers (MC), 20 nonmanifesting mutation carriers (NMC), and 110 controls. Participants underwent a standardized neurological examination, the University of Pennsylvania Smell Identification Test (UPSIT), the Farnsworth‐Munsell (FM) color discrimination test, and mutation testing in known PD genes. The monogenic group consisted of 15 Parkin (6MC/9NMC), 17 PINK1 (10MC/7NMC), 8 LRRK2 (4MC/4NMC), 3 SNCA (MC), and 4 ATP13A2 (MC) carriers. Olfaction was most impaired in IPD (UPSIT percentiles 10.1 ± 13.5) compared with all other groups (MC 13.8 ± 11.9, NMC 19.6 ± 13.0, controls 33.8 ± 22.4). Within MC, carriers of two mutations in Parkin and PINK1 showed higher UPSIT percentiles than LRRK2 and SNCA carriers. Color discrimination was reduced in IPD (FM total error score 134.8 ± 92.7). In MC (122.4 ± 142.4), the reduction was most pronounced in LRRK2, NMC (80.0 ± 38.8) were comparable with controls (97.2 ± 61.1). UPSIT and FM scores were correlated in the control (r = −0.305; P = 0.002) and the IPD group (r = −0.303; P = 0.006) but not among mutation carriers. First, we confirmed olfaction and color discrimination to be impaired in IPD and suggest olfaction to be a premotor sign. Second, olfaction differed between carriers with one and two mutations in Parkin/PINK1‐associated PD. Third, olfaction and color discrimination impairment do not necessarily evolve in parallel.

Dopaminergic response in Parkinsonian phenotype of Machado‐Joseph disease

We report on a patient with genetically proven Machado‐Joseph Disease (MJD) presenting with signs indistinguishable from Parkinsons disease (PD), including levodopa response and typical levodopa‐induced motor fluctuations. Only after 10 years of prolonged benefit from levodopa and different dopamine agonists (DA), the patient developed cerebellar ataxia and pyramidal signs. Preferential D3‐receptor–stimulating dopamine agonists especially showed a benefit at the time, when D2 receptor binding was reduced in IBZM SPECT. This is the first report of a meaningful response to DA in MJD.

Effects of DBS, premotor rTMS, and levodopa on motor function and silent period in advanced Parkinson's disease†

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a widely used and highly effective treatment for patients with advanced Parkinsons disease (PD). Repetitive TMS (rTMS) applied to motor cortical areas has also been shown to improve symptoms in PD and modulate motor cortical excitability. Here, we compared clinical and neurophysiological effects of STN stimulation with those of 1 Hz rTMS given to the dorsal premotor cortex (PMd) and those following intake of levodopa in a group of PD patients with advanced disease. Ten PD patients were studied on 2 consecutive days before and after surgery. Clinical effects were determined using the UPDRS motor score. Motor thresholds, motor‐evoked potential (MEP) amplitudes during slight voluntary contraction, and the cortical silent periods (SP) were measured using TMS. Before surgery effects of levodopa and 1 Hz PMd rTMS and after surgery those of STN stimulation with or without additional levodopa were determined. Levodopa significantly improved clinical symptoms and increased the SP duration. STN stimulation improved clinical symptoms without changing the SP duration. In contrast, 1 Hz PMd rTMS was not effective clinically but normalized the SP duration. Whereas levodopa had widespread effects at different levels of an abnormally active motor network in PD, STN stimulation and PMd rTMS led to either clinical improvement or SP normalization, i.e., only partially reversed abnormal motor network activity.

Wearable sensor-based objective assessment of motor symptoms in Parkinson’s disease

Effective management and development of new treatment strategies of motor symptoms in Parkinson’s disease (PD) largely depend on clinical rating instruments like the Unified PD rating scale (UPDRS) and the modified abnormal involuntary movement scale (mAIMS). Regarding inter-rater variability and continuous monitoring, clinical rating scales have various limitations. Patient-administered questionnaires such as the PD home diary to assess motor stages and fluctuations in late-stage PD are frequently used in clinical routine and as clinical trial endpoints, but diary/questionnaire are tiring, and recall bias impacts on data quality, particularly in patients with cognitive dysfunction or depression. Consequently, there is a strong need for continuous and objective monitoring of motor symptoms in PD for improving therapeutic regimen and for usage in clinical trials. Recent advances in battery technology, movement sensors such as gyroscopes, accelerometers and information technology boosted the field of objective measurement of movement in everyday life and medicine using wearable sensors allowing continuous (long-term) monitoring. This systematic review summarizes the current wearable sensor-based devices to objectively assess the various motor symptoms of PD.

Increased prevalence of and gene transcription by Chlamydia pneumoniae in cerebrospinal fluid of patients with relapsing-remitting multiple sclerosis

Abstract.Microbial agents may play a role in the pathogenesis of multiple sclerosis (MS). C. pneumoniae has been recently associated with MS; however, study results are at variance. We tested the hypothesis that Chlamydia pneumoniae-specific DNA and RNA are more often detected in cerebrospinal fluid (CSF) of patients with multiple sclerosis than patients with other neurological diseases (OND). We investigated CSF samples from 84 patients with definite MS and 89 OND patients (n = 62 with normal CSF; n = 27 with pathological CSF) using a nested polymerase chain reaction (PCR) to detect ompA gene sequences of C. pneumoniae. In subjects with positive PCR, we probed for chlamydial heat shock protein 60-mRNA and 16S-rRNA by reverse transcriptase (rt)-PCR. C. pneumoniae-specific DNA was more often detected in MS patients (50 %) than in all OND patients combined (28.1%, p = 0.003) and in OND patients with normal CSF (24.2%, p = 0.003) but not than in OND patients with pathological CSF (37%, p = 0.24). In relapsing-remitting MS (n = 55), the prevalence of C. pneumoniae DNA was higher (66.7 %) than in both OND subgroups (p ≤ 0.05). In MS patients (n = 20), chlamydial heat shock protein 60-mRNA (75%) and 16S-rRNA (70%) were more often detected than in OND patients (n = 16; 18.8%; p < 0.005).Although more often detected in remitting-relapsing MS, C. pneumoniae DNA in CSF is not specific for MS owing to its high prevalence in OND controls. However, the higher rate of gene transcription suggests a more active metabolism of C. pneumoniae in MS patients.

Failure of ondansetron in treating cerebellar tremor in MS patients - an open-label pilot study

Cerebellar tremor is a frequent and disabling symptom in multiple sclerosis (MS) patients. Supportive pharmacological treatment with different drugs showed only minor effects in a few studies and in clinical practice. Encouraged by previous studies with ondansetron, a 5HT3‐antagonist, we conducted a small open‐label, prospective and controlled study with 14 MS patients suffering predominantly from cerebellar tremor of the upper extremities. Principal outcome measure to evaluate a functional improvement of the single intravenous administered ondansetron injection was the subject performance in the 9‐hole‐peg‐test (9HPT) and 3 blind assessed upper extremity writing and copying tasks. We neither found significant improvement in the upper extremity tests nor in the subjective response of the patients. In conclusion we could not confirm a beneficial effect of ondansetron on cerebellar tremor of MS patients.