Coherent corticomuscular oscillations originate from primary motor cortex: evidence from patients with early brain lesions.

Coherent oscillations of neurons in the primary motor cortex (M1) have been shown to be involved in the corticospinal control of muscle activity. This interaction between M1 and muscle can be measured by the analysis of corticomuscular coherence in the beta-frequency range (beta-CMCoh; 14-30 Hz). Largely based on magnetoencephalographic (MEG) source-modeling data, it is widely assumed that beta-CMCoh reflects direct coupling between M1 and muscle. Deafferentation is capable of modulating beta-CMCoh, however, and therefore the influence of reafferent somatosensory signaling and corresponding neuronal activity in the somatosensory cortex (S1) has been unclear. We present transcranial magnetic stimulation (TMS) and MEG data from three adult patients suffering from congenital hemiparesis due to pre- and perinatally acquired lesions of the pyramidal tract. In these patients, interhemispheric reorganization had resulted in relocation of M1 to the contralesional hemisphere, ipsilateral to the paretic hand, whereas S1 had remained in the lesioned hemisphere. This topographic dichotomy allowed for an unequivocal topographic differentiation of M1 and S1 with MEG (which is not possible if M1 and S1 are directly adjacent within one hemisphere). In all patients, beta-CMCoh originated from the contralesional M1, in accordance with the TMS-evoked motor responses, and in contrast to the somatosensory evoked fields (SEFs) for which the sources (N20m) were localized in S1 of the lesioned hemisphere. These data provide direct evidence for the concept that beta-CMCoh reflects the motorcortical efferent drive from M1 to the spinal motoneuron pool and muscle. No evidence was found for a relevant contribution of neuronal activity in S1 to beta-CMCoh.

Enhanced episodic-like memory and kindling epilepsy in a rat model of tuberous sclerosis.

Tuberous sclerosis complex (TSC) is a common neurological autosomal-dominant syndrome caused by mutations in the TSC1 or TSC2 genes. TSC starts in early childhood and is characterized by cerebral hamartomas (benign tumours), severe epilepsy and cognitive deficits such as mental retardation and autism. The hamartomas are characterized by loss of the remaining wild-type TSC allele, and clinical data implicate cerebral hamartomas in the generation of epileptic seizures, which may play a significant role in the development of mental retardation. The TSC2 mutation predicts alterations in mitogen-associated protein kinase (MAPK) and, together with the TSC1 mutation, in mammalian target of rapamycin (mTOR) signalling pathways. Both pathways are involved in neuronal plasticity. We therefore hypothesized that the heterozygous mutation itself, besides cerebral hamartomas, contributes to the pathogenesis of cognitive deficits and possibly also epilepsy. Here, we show that young adult TSC2+/- rats, which are virtually free of cerebral hamartomas, exhibit enhanced episodic-like memory and enhanced responses to chemically-induced kindling. The activation of cyclic adenosine monophosphate (cAMP) in the hippocampus results in stronger induction of phospho-p42-MAPK in TSC2+/- rats than in wild-type animals. Thus, the cognitive phenotype and, possibly, epilepsy in TSC patients may result not only from the focal hamartomatous lesions but also, from altered neuronal plasticity in the heterozygous tissue.

Clinical and magnetic resonance imaging characteristics of sporadic cerebellar ataxia.

BACKGROUND: It is unknown whether multiple system atrophy of the cerebellar type (MSA-C) and idiopathic cerebellar ataxia with extracerebellar presentation (IDCA-P) represent distinct entities. OBJECTIVE: To investigate the discriminative validity of magnetic resonance imaging in sporadic cerebellar ataxia. DESIGN: Basal ganglia and infratentorial structures were screened for signal abnormalities and atrophic changes. Magnetic resonance imaging raters were masked to the clinical diagnosis. SETTING: Outpatient clinic of a university hospital. PATIENTS: Forty-one individuals were diagnosed as having MSA-C (n = 30) or IDCA-P (n = 11) based on their clinical features. RESULTS: Shrinkage of the cerebellar vermis and hemispheres was found in both groups. Atrophy of the brainstem and middle cerebellar peduncles was significantly more frequent in patients with MSA-C (P<.001). Hyperintensities of infratentorial structures were common in patients with MSA-C (middle cerebellar peduncles: 87%; pons: 97%) but were absent in patients with IDCA-P. Hypointensities or hyperintensities of basal ganglia structures did not reliably differentiate the groups. CONCLUSIONS: Patients with MSA-C were characterized by a higher frequency and severity of magnetic resonance imaging abnormalities (atrophic changes and additional hyperintense signal changes) of the middle cerebellar peduncles and pons. The presence of these magnetic resonance imaging features points to the diagnosis of MSA-C and helps differentiate MSA-C from other types of sporadic cerebellar ataxia with extracerebellar features.

UKT-04 trial of continuous metronomic low-dose chemotherapy with methotrexate and cyclophosphamide for recurrent glioblastoma.

Glioblastoma is a highly angiogenic tumor with a dismal prognosis. Continuous oral low-dose chemotherapy with methotrexate (MTX) and cyclophosphamide (CPM) has modest activity in heavily pretreated patients with breast cancer. We explored the efficacy of 100 mg CPM daily and 5 mg MTX twice weekly in relapsed glioblastoma. Ten patients, 22-59 years old, with a Karnofsky score of 50% or higher who had failed at least two chemotherapies were accrued. No toxicity was observed. No patient showed a complete or partial response. Five of 10 patients progressed within 2 months of therapy. Another five patients progressed after 3-4.5 months. The median time to progression was 2.5 months. The median overall survival after start of MTX/CPM was 6.9 months (range 0.5-18.8 months). Since the progression-free survival rate at 6 months was 0%, the trial was prematurely closed.

Monocyte-derived HLA-G acts as a strong inhibitor of autologous CD4 T cell activation and is upregulated by interferon-beta in vitro and in vivo: rationale for the therapy of multiple sclerosis.

Peripheral antigen presenting cells (APCs) contribute to the maintenance of immune tolerance and are considered to play a critical role in promoting the (re)activation of autoreactive T cells in multiple sclerosis (MS). Interferon-beta (IFN-beta) is the principle immune-modulatory agent used in the treatment of MS, but its mechanism of action remains elusive. HLA-G is a non-classical MHC molecule (MHC class Ib) attributed chiefly immune-regulatory functions. We here investigated the role of monocyte-derived HLA-G in the immune-regulatory processes of MS and its implications for current immune-modulatory therapies. Monocytes constitutively express cell surface HLA-G1 and soluble HLA-G5. Comparison of monocytic HLA-G expression between patients with relapsing-remitting MS (n=17) and healthy donors (n=20) revealed significantly lower levels of HLA-G1 protein in MS patients. However, both groups showed a significant upregulation of HLA-G in response to IFN-beta in vitro. Serial measurements of HLA-G mRNA levels in MS patients before and during IFN-beta therapy corroborated the relevance of these results in vivo: 1 month after initiation of IFN-beta1b therapy (n=9), HLA-G1 and HLA-G5 were significantly increased compared to baseline levels and remained elevated during treatment for 6 months (n=3). Importantly, functional experiments demonstrated that monocyte-derived HLA-G inhibits both Th1 (IFN-gamma, IL-2) and Th2 (IL-10) cytokine production by antigen-stimulated autologous CD4 T cells. Soluble HLA-G added to antigen-specific T cell lines (TCLs) has similar effects on the release of cytokines and reduces T cell proliferation. Although both IFN-beta and IFN-gamma strongly enhance HLA-G1 and HLA-G5 expression by monocytes in vitro, IFN-beta leads to a stronger relative upregulation of HLA-G compared to classical MHC class I molecules than stimulation with IFN-gamma. Taken together, monocyte-derived HLA-G mediates the inhibition of autologous CD4 T cell activation and might be involved in immune-regulatory pathways in the pathogenesis of MS. We conclude that some desirable immune-modulatory effects of INF-beta might be accomplished via the upregulation of the immune-tolerogenic molecule HLA-G.

Chemotherapy-induced cell death in primary cerebellar granule neurons but not in astrocytes: in vitro paradigm of differential neurotoxicity.

The nervous system is frequently the site of symptomatic toxicity of antineoplastic agents. However, there is limited information about the differential vulnerability of neurons, astrocytes and glioma cells. We have analyzed the effects of four chemotherapeutic drugs (lomustine, cisplatin, topotecan and vincristine) on primary cerebellar granule neurons and astrocytes derived from rats. All drugs led to cell death in cerebellar granule neurons in a concentration-dependent manner. Comparison of the EC50 values for cerebellar neurons and astrocytes with the median EC50 values of 12 malignant glioma cell lines demonstrated a large therapeutic range for lomustin and cisplatin. Further, this comparison revealed a 100-fold higher sensitivity of cerebellar neurons towards vincristine and 10-fold higher sensitivity towards topotecan compared with glioma cells. Astrocytes were generally resistant to vincristine. In cerebellar granule neurons, vincristine and to a lesser extent topotecan induced caspase 3 and caspase 9 cleavage, and enhanced caspase activity and Akt-dependent expression of phosphorylated BAD. zVAD-fmk, a caspase inhibitor and brain-derived neurotrophic factor (BDNF), but not MK-801, a non-competitive NMDA receptor antagonist, significantly reduced vincristine- or topotecan-induced cell death.

Intracranial metastatic esthesioneuroblastoma responsive to temozolomide.

Successful management of a heavily pretreated 58-year-old woman with metastatic esthesioneuoblastoma using temozolomide is reported. There is no standard treatment of this tumors with extra- and intracranial manifestations. The response, long term stability and high quality of life using temozolomide for this tumor entity should be recognized.

Characterization of motor skill and instrumental learning time scales in a skilled reaching task in rat.

Successful motor skill learning requires repetitive training interrupted by rest periods. In humans, improvement occurs within and between training sessions reflecting fast and slow components of motor learning [Karni A, Meyer G, Rey-Hipolito C, Jezzard P, Adams MM, Turner R, et al. The acquisition of skilled motor performance: fast and slow experience-driven changes in primary motor cortex. Proc Natl Acad Sci USA 1998;95:861-8]. Here, these components are characterized in male and female rats using a model of skilled forelimb reaching and are compared to time scales of instrumental learning. Twenty female and 14 male adult Long-Evans rats were pre-trained to operate a motorized door (via a sensor in the opposite cage wall) to access a food pellet by tongue. Latencies between pellet removal and door opening were recorded as measures of instrumental learning. After criterion performance was achieved, skilled forelimb reaching was requested by increasing the pellet-window distance to 1.5cm. Reaching success was recorded per trial. Mean latencies decreased exponentially over sessions and no improvement within-session was found. Skill learning over eight training sessions followed an exponential course in females and a sigmoid course in males. Females acquired the skill significantly faster than males starting at higher baseline levels (P < 0.001) but reaching similar plateaus. Within-session improvement was found during the sessions 1-3 in females and 1-4 in males. Performance at the end of session 1 was not carried over to session 2. Learning curves of individual animals were highly variable. These findings confirm in rat that motor skill learning has fast and slow components. No within-session improvement is seen in instrumental learning.

Leptomeningeal metastasis: survival and prognostic factors in 155 patients.

In this single-center retrospective study, 155 consecutive patients with leptomeningeal metastasis (LM) were analyzed for the prognostic role of patient- and therapy-related variables. Ten percent of the patients received radiotherapy alone, 32% had chemotherapy alone, 31% received radiochemotherapy, 17% had supportive therapy only, and 10% were not evaluable for therapy. Chemotherapy was systemic (17%), combined systemic and intrathecal (10%), or intrathecal only (35%). Clinical improvement was noted in 41% of the patients. Overall median survival time (MST) was 4.8 months. Survival varied considerably depending on the type of primary tumor in this largest published cohort of LM patients. Univariate Cox regression analysis revealed that age >60 and elevated cerebrospinal fluid (CSF) albumin or lactate levels were therapy-independent predictors of poor survival in the entire cohort as well as in the subgroup of patients with systemic primary tumors (n=105). The assessment of three therapy-independent parameters allows to group LM patients into groups of low, intermediate, and high risk of poor survival. Moreover, the application of systemic chemotherapy was a positive prognostic factor in patients with subarachnoid lesions detected by neuroimaging (RR 1.94, p=0.001) or with extra-CNS tumor deposits (RR 1.52, p=0.05). The results of this study suggest that systemic chemotherapy alone or in combination with other therapeutic modalities may improve outcome in patients with subarachnoid tumor cell deposits detectable by neuroimaging.

Protein synthesis inhibition blocks consolidation of an acrobatic motor skill.

To investigate whether motor skill learning depends on de novo protein synthesis, adult rats were trained in an acrobatic locomotor task (accelerating rotarod) for 7 d. Animals were systemically injected with cycloheximide (CHX, 0.5 mg/kg, i.p.) 1 h before sessions 1 and 2 or sessions 2 and 3. Control rats received vehicle injections before sessions 1, 2, and 3. Although CHX did not affect improvement of performance within session 1, between-session improvement was impaired. In overtrained animals, comparable injections of CHX had no effect on rotarod performance. These findings suggest that consolidation of motor skills requires protein synthesis.

Motor skill learning depends on protein synthesis in motor cortex after training.

The role of protein synthesis in memory consolidation is well established for hippocampus-dependent learning and synaptic plasticity. Whether protein synthesis is required for motor skill learning is unknown. We hypothesized that skill learning is interrupted by protein synthesis inhibition (PSI). We intended to test whether local protein synthesis in motor cortex or cerebellum is required during skill acquisition and consolidation. Anisomycin (ANI; 100 microg/microl in 1 microl of PBS) injected into motor cortex, posterior parietal cortex, or cerebellum produced 84.0 +/- 1.44% (mean +/- SEM), 85.9 +/- 2.31%, and 87.3 +/- 0.17% of PSI 60 min after administration, respectively. In motor cortex, protein synthesis was still reduced at 24 hr (72.0 +/- 4.68% PSI) but normalized at 48 hr after a second injection given 24 hr after the first. To test for the effects of PSI on learning of a skilled reaching task, ANI was injected into motor cortex contralateral to the trained limb or into ipsilateral cerebellum immediately after daily training sessions 1 and 2. Two control groups received motor cortex injections of vehicle or ANI injections into contralateral parietal cortex. Control and cerebellar animals showed a sigmoid learning curve, which plateaued after day 4. PSI in motor cortex significantly reduced learning during days 1-4. Thereafter, when protein synthesis normalized, learning was reinitiated. ANI injections into motor cortex did not induce a motor deficit, because animals injected during the performance plateau did not deteriorate. This demonstrates that motor skill learning depends on de novo synthesis of proteins in motor cortex after training.

Diffusion-weighted MRI of spinal cord infarction--high resolution imaging and time course of diffusion abnormality.

Infarction is a rare cause of spinal cord dysfunction. Whereas diffusion-weighted (DW) MRI has been established as a highly sensitive technique for assessing acute cerebral ischemia, its role in spinal cord infarction remains to be determined. The purpose of this study is to present the signal characteristics of acute spinal cord ischemia using DWMRI within the first two days and after one week. MRI including DW imaging (DWI) was performed in three patients with acute spinal cord dysfunction 8, 12 and 30 hours after the onset of symptoms and repeated after one week in two patients. Two initial scans included EPI DW sequences in transverse and sagittal orientation. The remaining examinations were performed with an optimised high-spatial resolution DWI sequence in the transverse plane. The diagnosis of spinal cord ischemia was established by imaging, clinical history and CSF analysis. T2 signal abnormality and restricted diffusion was demonstrated in all initial examinations. Transverse DW sequences had the highest sensitivity. The spinal infarctions were mainly located in the centre of the spinal cord and the grey matter. Contrast enhancement was absent. After one week, the restricted diffusion had normalised (pseudo normalisation) whereas the T2 signal changes had become more prominent. Restricted diffusion in the course of spinal cord ischemic infarction can be demonstrated using DW-MRI. Whereas a diffusion abnormality can be found after few hours, it does not last for longer than one week. At this time, the establishment of the diagnosis has to rely mainly on T2-weighted images with additional post contrast T1-weighted images being useful.

Short and long-term motor skill learning in an accelerated rotarod training paradigm.

Rodent models of motor skill learning include skilled forelimb reaching and acrobatic locomotor paradigms. This study characterizes motor skill learning in the accelerated rotarod task. Thirty Long-Evans rats (300-400 g) were trained on an accelerated rotarod (1cm/s(2)) over eight consecutive sessions (=days, 20 trials each). Improvement in rotarod velocities mastered before falling off the rod was observed within and between sessions (plateau after five sessions). Intrasession improvement was incompletely retained at the beginning of the next day's session. Over several training sessions, intrasession improvement diminished, suggesting a ceiling effect. After 1 week of pause, the rotarod skill was retained. Locomotor exercise in a running wheel for 30 min before the first rotarod session did not affect intrasession improvement. Running-wheel exposure for 6 days did not diminish the rate of rotarod skill learning (steepness of the learning curve) but improved overall performance (upward shift of curve). Video analysis of gait on the rotarod showed that rats developed a motor strategy by modifying their gait patterns during training. The data demonstrate that rotarod improvement is not the result of enhanced general locomotor ability or fitness, which are trained in the running wheel, but requires a change in the motor strategy to master the task. Accelerated rotarod training can be regarded a valid paradigm for motor skill learning over short (intrasession, minutes) and long time frames (intersession, days).

Magnetic resonance imaging-based volumetry differentiates progressive supranuclear palsy from corticobasal degeneration.

Because there are no biological markers for the clinical diagnosis of progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), we established a mathematical model based on three-dimensional magnetic resonance (MR) imaging to differentiate between these parkinsonian disorders. Using MR imaging-based volumetry we studied the pattern of atrophic changes in patients with probable, possible or definite PSP (n = 33) or CBD (n = 18). Patients were compared with 22 controls with similar age. To establish a mathematical model that would allow for differentiation of PSP, CBD and controls we performed a discriminant analysis. We found a significant reduction in average brain, brainstem, midbrain and frontal gray matter volumes in patients with PSP, whereas patients with CBD showed atrophy of parietal cortex and corpus callosum. With the exception of reduced midbrain volumes in PSP, the measured volumes of anatomical structures showed an extensive overlap with the normal range on an individual basis. Using only post mortem confirmed cases of PSP (n = 8) and CBD (n = 7) as well as all controls, the volumes of midbrain, parietal white matter, temporal gray matter, brainstem, frontal white matter and pons were identified to separate best between groups and were used to construct a model with two canonical variables. This model allowed to correctly predict the diagnosis in 95% of controls as well as in 76% of all PSP and 83% of all CBD patients. Similar results were obtained only when patients with a possible and probable diagnosis of PSP and CBD, who were not involved in the development of the discriminant analysis, were classified. 3D-MR imaging-based volumetry may help to differentiate PSP from CBD ante mortem.

Protection by pioglitazone in the MPTP model of Parkinson's disease correlates with I kappa B alpha induction and block of NF kappa B and iNOS activation.

Inflammation has been implicated in the pathogenesis of Parkinson's disease (PD). In the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD, inducible NO synthase (iNOS) derived nitric oxide (NO) is an important mediator of dopaminergic cell death. Ligands of the peroxisome proliferator-activated receptor (PPAR) exert anti-inflammatory effects. We here investigated whether pioglitazone, a PPARgamma agonist, protected mice from MPTP-induced dopaminergic cell loss, glial activation, and loss of catecholamines in the striatum. As shown by western blot, PPARgamma was expressed in the striatum and the substantia nigra of vehicle- and MPTP-treated mice. Oral administration of 20 mg/(kg day) of pioglitazone protected tyrosine hydroxylase (TH)-positive substantia nigra neurons from death induced by 5 x 30 mg/kg MPTP. However, the decrease of dopamine in the striatum was only partially prevented. In mice treated with pioglitazone, there were a reduced activation of microglia, reduced induction of iNOS-positive cells and less glial fibrillary acidic protein positive cells in both striatum and substantia nigra pars compacta. In addition, treatment with pioglitazone almost completely blocked staining of TH-positive neurons for nitrotyrosine, a marker of NO-mediated cell damage. Because an increase in inhibitory protein-kappa-Balpha (IkappaBalpha) expression and inhibition of translocation of the nuclear factor kappaB (NFkappaB) subunit p65 to the nucleus in dopaminergic neurons, glial cells and astrocytes correlated with the protective effects of pioglitazone, our results suggest that pioglitazone sequentially acts through PPARgamma activation, IkappaBalpha induction, block of NFkappaB activation, iNOS induction and NO-mediated toxicity. In conclusion, treatment with pioglitazone may offer a treatment opportunity in PD to slow the progression of disease that is mediated by inflammation.

MICA/NKG2D-mediated immunogene therapy of experimental gliomas.

The failure of conventional cancer therapy renders glioblastoma an attractive target for immunotherapy. Tumor cells expressing ligands of the activating immunoreceptor NKG2D stimulate tumor immunity mediated by natural killer (NK), gammadelta T, and CD8(+) T cells. We report that human glioma cells express the NKG2D ligands MICA, MICB, and members of the UL16-binding protein family constitutively. However, glioma cells resist NK cell cytolysis because of high MHC class I antigen expression. Plasmid-mediated or adenovirus-mediated overexpression of MICA in glioma cells enhances their sensitivity to NK and T-cell responses in vitro and markedly delays the growth of s.c. and intracerebral LN-229 human glioma cell xenografts in nude mice and of SMA-560 gliomas in syngeneic VMDk mice. Glioma cells forming progressive tumors after implantation of stably MICA-transfected human LN-229 cells lost MICA expression, indicating a strong selection against MICA expression in vivo. Rejection of MICA-expressing SMA-560 cells in VMDk mice resulted in protective immunity to a subsequent challenge with wild-type tumor cells. Finally, the growth of syngeneic intracerebral SMA-560 tumors is inhibited by peripheral vaccination with adenovirus-mediated, MICA-infected irradiated tumor cells, and vaccination results in immune cell activation in the NK and T-cell compartments in vivo. These data commend MICA immunogene therapy as a novel experimental treatment for human malignant gliomas.

Action of treosulfan in myelin-oligodendrocyte-glycoprotein-induced experimental autoimmune encephalomyelitis and human lymphocytes.

Treosulfan (dihydroxybusulfane, DHB, L-threitol-1,4-bis [methane sulfonate]) is a cytostatic alkylating agent with a favorable profile of side effects. Myelin-oligodendrocyte-glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) induced in DA (RT1(av1)) rats resembles multiple sclerosis (MS) in many aspects since central nervous system (CNS) pathology shows inflammation, demyelination and axonal loss. Moreover, DA rats develop a chronic disease course. We here explored the efficacy of treosulfan in the treatment of MOG-induced EAE in DA rats. A single dose of treosulfan (1 g/kg body weight i.p.) at the day of immunization significantly reduced disease severity compared with PBS-treated controls. In addition, after disease had evolved, a single dose of treosulfan (1 g/kg body weight) given i.p. on day 14 post-immunization (p.i.) improved long-term disease outcome. Treatment with treosulfan resulted in reduced mRNA expression of IL-12 and interferon (IFN)-gamma in draining lymph nodes and reduced numbers of IFN-gamma-secreting MOG-specific T cells. No myelosuppression was observed. Treosulfan was applied to different subsets of cultured human blood mononuclear cells in order to asses the effects on human immune cells in vitro: Treosulfan reduced proliferative capacity and increased apoptosis in T cells and antigen-presenting cells. In light of the beneficial effects in EAE in vivo and the in vitro immunosuppressive and pro-apoptotic capacities in cultured human mononuclear immune effector cells, these data may support a potential role of treosulfan, an agent with high immunosuppressive capacity and low toxicity, in the treatment of MS.