Deciphering the causes of sporadic late-onset cerebellar ataxias: a prospective study with implications for diagnostic work.

The management of sporadic late-onset cerebellar ataxias represents a very heterogeneous group of patients and remains a challenge for neurologist in clinical practice. We aimed at describing the different causes of sporadic late-onset cerebellar ataxias that were diagnosed following standardized, exhaustive investigations and the population characteristics according to the aetiologies as well as at evaluating the relevance of these investigations. All patients consecutively referred to our centre due to sporadic, progressive cerebellar ataxia occurring after 40 years of age were included in the prospective, observational study. 80 patients were included over a 2 year period. A diagnosis was established for 52 patients (65%) corresponding to 18 distinct causes, the most frequent being cerebellar variant of multiple system atrophy (n = 29). The second most frequent cause was inherited diseases (including spinocerebellar ataxias, late-onset Friedreich's disease, SLC20A2 mutations, FXTAS, MELAS, and other mitochondrial diseases) (n = 9), followed by immune-mediated or other acquired causes. The group of patient without diagnosis showed a slower worsening of ataxia (p < 0.05) than patients with multiple system atrophy. Patients with later age at onset experienced faster progression of ataxia (p = 0.001) and more frequently parkinsonism (p < 0.05) than patients with earlier onset. Brain MRI, DaT scan, genetic analysis and to some extent muscle biopsy, thoracic-abdominal-pelvic tomodensitometry, and cerebrospinal fluid analysis were the most relevant investigations to explore sporadic late-onset cerebellar ataxia. Sporadic late-onset cerebellar ataxias should be exhaustively investigated to identify the underlying causes that are numerous, including inherited causes, but dominated by multiple system atrophy.

Is deltoid muscle biopsy useful in isolated camptocormia? A prospective study.

BACKGROUND AND PURPOSE: Camptocormia is a marked anterior curvature of the thoracolumbar spine that may be caused by parkinsonism, amyotrophic lateral sclerosis (ALS), myasthenia gravis (MG) and muscle disease. The interest of a systematic muscle biopsy has not been evaluated until now. In our study, the aim was to prospectively evaluate the proportion of patients with isolated camptocormia without ALS, MG and parkinsonism who have an underlying myopathy. METHODS: Twenty consecutive patients (75% female, mean age 70 years) with isolated camptocormia were enrolled in a single centre in this 5-year prospective study. ALS, MG and parkinsonism had been excluded in all cases. A left deltoid muscle biopsy was performed in all patients and processed with standard techniques for histology and immunohistochemistry. Additional biochemical and genetic studies were performed when pathological analysis was consistent with myopathy. RESULTS: A myopathy was identified in seven patients (35%). Three patients presented with mitochondrial myopathy, including two patients harbouring a heterozygous POLG gene pathogenic variant and one patient with a heterozygous RRM2B gene pathogenic variant. Two patients presented with an inflammatory myopathy, including one with anti-PM/Scl antibodies. One patient presented with facioscapulohumeral muscular dystrophy and one patient with an MYH7 gene-related myofibrillar myopathy. No obvious myopathy was found in the 13 remaining cases. DISCUSSION: In this prospective study, an underlying myopathy was found in 35% of patients with isolated camptocormia. These results suggest that a muscle biopsy should be systematically performed in patients with isolated camptocormia when ALS, MG and parkinsonism have been excluded.

[Immune-mediated necrotizing myopathy associated with antibodies to hydroxy-methyl-glutaryl-coenzyme A reductase]. / Myopathie nécrosante auto-immune associée aux anticorps anti-hydroxy-méthyl-glutaryl-coenzyme A réductase.

INTRODUCTION: Statins or 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (HMGCR) are among the most commonly prescribed treatment in France. They may be responsible for muscular intolerance with variable severity. They have been recently involved in the occurrence of an acquired inflammatory myopathy associated with anti-HMGCR antibodies. This new type of toxic myopathy remains poorly known by clinicians. OBSERVATION: We report a 61-year-old woman treated with a statin for many years who developed a lower and upper limb disabling myopathy with a rapid unfavourable course despite treatment withdrawal. Clinical history and investigations, especially including an assay for anti-HMGCR antibodies led to the diagnosis of autoimmune necrotizing myopathy with anti-HMGCR antibodies. Subsequent initiation of an immunosuppressive treatment by corticosteroids and methotrexate was effective. CONCLUSION: Statins may unmask or cause an autoimmune necrotizing myopathy associated with the presence of anti-HMGCR antibodies. Their identification is now routinely available. An immunosuppressive treatment is necessary and justified by the autoimmune nature of the disease.

[HER2 gene amplification assay: is CISH an alternative to FISH?]. / Recherche de l'amplification du gène HER2: la CISH est-elle une alternative à la technique FISH?

The HER2 proto-oncogene encodes a transmembrane protein, which is considered to function as a growth factor receptor. Overexpression of this protein found by immunohistochemistry in about 20% of infiltrating breast carcinomas, has a predictive value of response to treatment by trastuzumab, an anti-HER2 humanized monoclonal antibody. Search for HER2 gene amplification is necessary to adapt the immunohistochemical technique quality and also in the cases of delicate analysis or weak overexpression. It is usually carried out by Fluorescence In Situ Hybridization (FISH). A more recent hybridization technique, named CISH because of its chromogenic revelation is an alternative method, which gives highly correlated results with FISH. We present details of this technique, which may be more familiar for the pathologists than FISH, because reading analysis is similar to that of immunohistochemical staining.

Sensitization of the striatal dopaminergic system induced by chronic administration of a glutamate antagonist in the rat.

The aim of the present study was to assess in the rat the pharmacological, biochemical and molecular (including in situ hybridization) consequences in the striatum of a prolonged (50 days) treatment with dizocilpine maleate (MK-801), an N-methyl-D-aspartate (NMDA) antagonist. We observed a sensitization-like effect characterized by a behavioural hyperresponsiveness to an acute injection of haloperidol (0.25 mg/kg), a dopaminergic antagonist. In rats chronically treated with MK-801, this hyperresponsiveness was associated with an increased D2 receptor (D2R) density in the striatum. At the transcriptional level, the D2R mRNA was also enhanced in the striatum. Quantitative in situ hybridization studies revealed that the number of neurons expressing the D2R mRNA was significantly enhanced in treated rats, whereas the mean amount of message per cell was unchanged. These changes could represent the neurobiological substrate of the observed sensitization. These results suggest that the D2R gene is under glutamate control via NMDA receptor in striatal neurons.

kappa-Opioid receptor in humans: cDNA and genomic cloning, chromosomal assignment, functional expression, pharmacology, and expression pattern in the central nervous system.

Using the mouse delta-opioid receptor cDNA as a probe, we have isolated genomic clones encoding the human mu- and kappa-opioid receptor genes. Their organization appears similar to that of the human delta receptor gene, with exon-intron boundaries located after putative transmembrane domains 1 and 4. The kappa gene was mapped at position q11-12 in human chromosome 8. A full-length cDNA encoding the human kappa-opioid receptor has been isolated. The cloned receptor expressed in COS cells presents a typical kappa 1 pharmacological profile and is negatively coupled to adenylate cyclase. The expression of kappa-opioid receptor mRNA in human brain, as estimated by reverse transcription-polymerase chain reaction, is consistent with the involvement of kappa-opioid receptors in pain perception, neuroendocrine physiology, affective behavior, and cognition. In situ hybridization studies performed on human fetal spinal cord demonstrate the presence of the transcript specifically in lamina II of the dorsal horn. Some divergences in structural, pharmacological, and anatomical properties are noted between the cloned human and rodent receptors.

Chronic treatment with dizocilpine maleate increases the number of striatal neurons expressing the D2 receptor gene.

N-methyl-D-aspartate antagonists have been proposed as potential therapeutic agents in different neurological diseases, including Parkinson's disease. The effects of gene expression of a chronic treatment with the non-competitive N-methyl-D-aspartate antagonist, dizocilpine maleate (0.8 mg/kg day, per os for 50 days) were analysed in rat striata. Using quantitative in situ hybridization, we measured the messenger RNA expression of the genes encoding D1, D2 dopamine receptors, N-methyl-D-aspartate receptor 1 subunit of N-methyl-D-aspartate receptor, preproenkephalin A and substance P. Chronic treatment with dizocilpine maleate induced a moderate but significant increase in messenger RNA of the N-methyl-D-aspartate receptor 1 subunit in the striatum and the adjacent cortex, suggesting an action of dizocilpine maleate in these two regions. This treatment did not induce any change in D1 receptor, preproenkephalin A or substance P messenger RNA content in the striatum, whereas D2 receptor messenger RNA was increased in the striatum of treated rats. Microscopic analysis revealed that it was the number of medium-sized neurons expressing D2 receptor messenger RNA that was significantly enhanced, while the mean amount of message per cell remained unchanged. These results demonstrate that glutamate via N-methyl-D-aspartate receptors, regulates the D2 receptor gene in striatal neurons. A chronic treatment with dizocilpine maleate increases the number of striatal neurons expressing the D2 receptor gene, suggesting a recruiting phenomenon.

The human delta-opioid receptor: genomic organization, cDNA cloning, functional expression, and distribution in human brain.

We have used the mouse delta-opioid receptor (mDOR) cDNA to isolate the mDOR gene and its human homologue. In both species the coding region is interrupted by two introns with conserved exon-intron boundaries located after transmembrane domains 1 and 4. Using the polymerase chain reaction and primers based on the sequence of the cloned human delta-opioid receptor (hDOR) gene, we have obtained a full length cDNA encoding the hDOR from SH-SY5Y neuroblastoma cells. The cDNA sequence is 100% identical to the cloned human genomic sequence and 94% identical to the mouse sequence at the protein level. When expressed in COS cells, hDOR displays nanomolar affinities for delta-selective ligands, whereas the affinities for mu- and kappa-selective ligands are in the micromolar range. The delta agonists [D-Ala2, D-Leu5]enkephalin, cyclic [D-penicillamine2,D-penicillamine5]enkephalin, and BW373U86 efficiently decrease forskolin-induced cAMP levels in hDOR-expressing COS cells, indicating functional coupling of the receptor. The distribution of hDOR mRNA in human brain was investigated using delta-selective reverse transcription-polymerase chain reaction amplification, followed by Southern hybridization with a delta-specific probe. The transcript is found in cortical areas, including olfactory bulb, hippocampus, and amygdala, as well as in basal ganglia and hypothalamus. No expression is detected in internal globus pallidus, thalamus, any investigated brainstem structure, or pituitary gland. Taken together, our results indicate similar structural, pharmacological, functional, and anatomical properties for the hDOR and the mDOR and therefore support the use of rodent models for the study of these receptors in opioid function.

[Anatomic-functional relationships between the motor systems and the sleep-wakefulness systems]. / Relations anatomofonctionnelles des systèmes moteurs avec les systèmes de veille et de sommeil.

The present paper deals with relationships between neural systems which control motor behaviour (pyramidal and extrapyramidal) and sleep-wakefulness states (in particular the reticular formation). We examined successively their anatomical and neurochemical substrates, electrophysiological and functional motor alterations depending on ascending and descending influences from brain stem during the sleep-wakefulness cycle. These data suggest that sleep-wake states result from the modulation of excitability in neuronal pools and that each state results from the co-ordinated working of several functionally different neuronal pools. Thus, each state could be understood as a sum of behavioural events depending on a neural network. We hypothesized that abnormal motor events occurring specifically during a sleep state could result from motor structures abnormally recruited in neural networks specifically involved in this sleep state.

Chronic administration of NMDA antagonists induces D2 receptor synthesis in rat striatum.

Dopamine D2 receptor gene expression was examined in rat striatum after chronic treatment with N-methyl-D-aspartate (NMDA) receptor antagonists (ketamine at 15 mg/kg/day or MK-801 at 0.1, 0.2 and 0.4 mg/kg/day per os, for 50 days). The long-isoform mRNA, as well as the total D2 mRNA expression were induced. No change was noticed in striatal dopamine release or turnover. D2 binding studies carried out in MK-801 chronically treated (0.3 mg/kg/day per os, for 50 days) and control rats revealed an increased receptor density in treated animals without a significant change in receptor affinity. These results suggest that the synthesis of both striatal D2 receptor isoforms is postsynaptically regulated at the transcriptional level, by events triggered by glutamate through the NMDA-type receptor.

[Chronic administration of N-methyl-D-aspartate (NMDA) receptor antagonists induced in rats, a facilitation of striatal dopaminergic type D2 transmission: behavioral and biochemical study]. / L'administration chronique d'antagonistes du récepteur N-méthyl-D-aspartate (NMDA) induit, chez le rat, une facilitation de la transmission dopaminergique striatale de type D2: étude comportementale et biochimique.

Compared with control rats, rats treated with ketamine (15 mg/kg/day, p.o.) or MK-801 (0.1 to 0.4 mg/kg/day, p.o.) for 6 weeks showed significantly increased: 1) behavioural responses to D2 dopaminergic agents, either agonist or antagonist, 2) striatal D2 receptor mRNA expression, 3) striatal D2 receptor density, without any presynaptic change in dopaminergic or serotoninergic neurotransmission. These results suggest that the functional expression of striatal D2 receptor is postsynaptically regulated by glutamate-triggered events through the NMDA receptor subtype.

Lesions of noradrenergic neurons in rats with spontaneous generalized non-convulsive epilepsy.

The role of noradrenergic neurons in the control of a spontaneous generalized non-convulsive epilepsy (GNCE) was investigated. In rats with genetic spontaneous absence seizures, we produced lesions using 2 neurotoxins: 6-hydroxydopamine (6-OHDA) and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4). Lesions of noradrenergic neurons were made either in pups by neonatal 6-OHDA intraperitoneal (i.p.) injection (2 x 100 mg/kg) or in adult rats by i.p. administration of DSP4 (60 mg/kg) or bilateral microinjection of 6-OHDA in the locus coeruleus (LC) (4 micrograms/microliters, 2 microliters/side). Effectiveness of the lesions was controlled by measuring dopamine (DA) and noradrenaline (NA) contents in the brains. Neonatal 6-OHDA administration did not lead to any difference in seizures in adult animals, compared with control rats. DSP4 injections and LC lesions with local injections of 6-OHDA produced a transient increase of the seizures. Within one to two weeks, the seizure duration went back to prelesion levels. No seizure occurred when the same lesions were performed in non epileptic rats. These results suggest that NA is not involved in the genesis of this generalized non-convulsive epilepsy; they confirm that NA participates in the control of seizures in this model, but the rapid development of compensatory mechanisms shows that this control is not critical.

Behavioural, pharmacological and biochemical effects of acute and chronic administration of ketamine in the rat.

The effects of N-methyl-D-aspartate (NMDA) antagonist ketamine given acutely or chronically were investigated on dopamine-related motor functions. Acute administration (15, 22.5, 30 mg/kg, i.p.) reversed the catalepsy induced by a dopamine (DA) antagonist (haloperidol, 0.25 mg/kg, i.p.) in the rat. When given orally and chronically (15 mg/kg per day) during at least 60 days, no alteration of spontaneous motor behaviour was observed, but the responsiveness to a DA agonist (apomorphine, 0.125 or 0.25 mg/kg s.c.) and to haloperidol was enhanced, suggesting an hypersensitivity of the DA receptors following the chronic blockade of NMDA receptors. However, following prolonged administration of ketamine there were no alteration of DA levels and turnover. Taken together these results suggest that the mechanisms involved in this DA receptor hypersensitivity should be postsynaptic.

[Mannosidosis type II]. / La mannosidose de type II.

Four out of 7 siblings born of non-consanguineous parents have presented psychomotor retardation, macrocephaly and facial dysmorphism associated in 2 of them with thoraco-lumbar kyphosis and in one of them with recurrent pulmonary infections which had resulted in death. Chromatography of oligosaccharides displayed a characteristic mannosidosis profile. In addition, D-mannosidase activity was very low in leucocytes and fibroblasts. The father and mother showed no clinical abnormality and had no pathological urinary oligosaccharide excretion, but their leucocyte and fibroblast D-mannosidase activity was reduced. These cases give the authors an opportunity to describe the clinical and biochemical features of mannosidosis, which in its type II enables the patients to survive into adulthood, and to underline the value of D-mannosidase assays to detect subjects with this anomaly.

Local cerebral glucose utilization in rats with petit mal-like seizures.

The quantitative 2-[14C]deoxyglucose autoradiographic method was applied to the measurement of local cerebral metabolic rates for glucose in a model of genetic petit mal-like seizures in a strain of Wistar rats. During the experimental period, epileptic rats exhibited synchronous spike-and-wave discharges recorded from the cerebral cortex, whereas the electroencephalographic pattern of control animals was normal. An overall consistent increase in local cerebral metabolic rates for glucose was observed in epileptic rats as compared to nonepileptic control rats. This increase was statistically significant in 52 of the 59 cerebral structures studied and concerned all cerebral functional systems. These results are in accordance with positron emission tomography measurements in humans with typical childhood absence epilepsy. There is a lack of anatomical correlation between areas demonstrating hypermetabolism and areas where spike-and-wave discharges are recorded. Thus, the diffuse increase in cerebral energy metabolism in epileptic rats as compared to controls is not directly related to the occurrence of spike and wave discharges.

Immediate effects of 14 non MAOI antidepressants in rats with spontaneous petit mal-like seizures.

1. Wistar rats of a strain presenting spontaneous petit mal-like seizures were injected intraperitoneally with graded doses of 14 non-monoamine oxidase inhibitor antidepressants and the immediate effects on behavior and the EEG were recorded. 2. Amineptine and nomifensine, the two drugs interacting with dopaminergic neurotransmission, reduced the duration of spontaneous spike-wave discharges (SWD) and were thus potentially antiepileptic. 3. Trazodone increased SWD duration. 4. The antidepressants, imipramine-like (imipramine, chlorimipramine, desipramine, metapramine and amitriptyline) and non-imipraminic (minaprine, maprotiline, viloxazine, mianserin, fluvoxamine and indalpine), and the 3 noted above, had potentially convulsive effects.

Interhemispheric desynchronization of spontaneous spike-wave discharges by corpus callosum transection in rats with petit mal-like epilepsy.

Wistar rats of a strain inbred for spontaneous generalized non-convulsive seizures present EEG spike-wave discharges (SWDs), 7-10 c/sec, occurring about once/min and lasting about 15 sec. They are bilateral and synchronous and can be recorded over the entire neocortex and in the lateral thalamic nuclei. After corpus callosum section, only a few bilateral SWDs persisted. Asymmetrical SWDs were most often recorded: bilateral SWDs starting asynchronously, or unilateral SWDs, which were also seen to alternate abruptly between hemispheres. The thalamic SWDs were always synchronized with the ipsilateral cortical pattern. These findings suggest that while the corpus callosum has a major role in bilateral synchronization of SWD in this model of epilepsy, occasional synchronization may still occur through other pathways after callosal transection.