Clinical neuroscience (New York, N.Y.)最新文献

The purpose of this review is to provide an overview of the acute actions of ethanol on signal transduction, as well as a selective consideration of some of the long-term adaptive changes in signal transduction pathways that may underlie clinical manifestations of ethanol dependence, tolerance, withdrawal, and addiction. The acute intoxicating effects of ethanol have been widely attributed to its ability to block voltage-gated Ca2+ and Na+ channels and N-methyl-D-aspartate glutamate receptor cation channels, and to facilitate GABAA receptor Cl- channels. Adaptive changes in these same proteins following chronic ethanol exposure may contribute to physical and psychological signs of ethanol dependence and withdrawal. Ethanol, as with other drugs of abuse, also acutely activates the mesolimbic dopamine pathway, an effect which likely accounts, at least in part, for ethanol's acute reinforcing properties. Studies directed at unraveling the biochemical and molecular basis of ethanol's acute and chronic actions may lead to the development of novel pharmacotherapeutics that mitigate aspects of acute ethanol intoxication and, more importantly, treat the effects of withdrawal and addiction (craving) associated with long-term ethanol abuse.

Amyotrophic lateral sclerosis (ALS) is a disease of unknown etiology. A number of theories have been pursued to explain the cause of ALS, including viral infection. This review examines the evidence implicating viruses in the pathogenesis of ALS, as well as current studies of naturally occurring and experimental models of virus-induced motor neuron disease (MND). The association of viruses and ALS remains to be established. The study of animal models of virus-induced MND may shed light on processes relevant to the etiology of ALS.

The evolution of our understanding of schizophrenia has provided new concepts that substantially alter answers to questions such as age of onset, distribution by sex, and treatment response. Moreover, these new concepts offer heuristic advantages in etiopathophysiological study designs and permit investigators to address key sources of artifact. We discuss the unitary versus the clinical syndromal concept of schizophrenia and describe the implications of the latter with regard to the study of schizophrenia. We also present a heuristic tripartite division of schizophrenic symptoms for reducing syndromal heterogeneity.

This article reviews evidence for morphological abnormalities in schizophrenia as assessed by brain imaging and neurohistochemical techniques including immunohistochemistry and in situ hybridization. Localized deficits in schizophrenic brain appear in many regions including frontal and temporal lobes, anterior cingulate, mediodorsal thalamic nucleus, and corpus callosum. These areas are interconnected and may provide the basis for a "psychosis circuitry." Neuronal disruption of elements in this circuitry may result in a hypothesized dysconnection syndrome. Evidence suggests an alteration in neuronal development related to either genetic and/or environmental factors. Primary and secondary anterograde and retrograde effects may accompany this neurodevelopmental defect and may further alter intrinsic and extrinsic neuronal communications. A number of studies are consistent with the second trimester of gestation being a critical period for fetal brain development, especially for neuronal migration. Fetal trauma due to environmental insults (e.g., influenza) during this trimester may increase the incidence of schizophrenia. Recent advances in the identification of factors that modulate neuronal development including axon guidance molecules, neurotrophins, and programmed cell death genes provide intriguing new areas for potential investigation. Future research may focus on the factors controlling neuronal migration and programmed cell death in the schizophrenic brain.

The inherited ataxias can now be classified on the basis of genotype rather than phenotype. Clinical expression of the various disorders overlap one another, making a diagnostic classification based on phenotype inaccurate in many instances. A genomic classification as outlined here has provided order and clarity in this group of disorders previously classified on the basis of clinical features. It is expected that in the near future the abnormal gene products for these ataxias, the ataxins, will be identified and provide molecular insights for effective therapies.

We review the evidence of pathophysiological changes in the prefrontal and temporal cortices of schizophrenic subjects and of abnormal integration of the physiological dynamics in these two regions. The argument we develop is that some schizophrenic phenomena are best understood in terms of abnormal interactions between different areas, not only at the levels of physiology and functional anatomy, but at the level of cognitive and sensorimotor functioning. We discuss recent functional imaging evidence suggesting abnormal prefronto-temporal interactions in relation to a psychological analysis of experiential symptoms in schizophrenia. Cortico-cortical interactions have been assessed in terms of functional connectivity and eigenimages, using time series of neurophysiological data obtained with positron emission tomography. The results of these analyses suggest that there is a profound disruption of large-scale prefronto-temporal interactions in schizophrenia. These disruptions are particularly relevant if one considers that many positive symptoms of schizophrenia reflect a failure to integrate intrinsically generated behaviour and concurrent perception.

Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare autosomal dominant neurodegenerative disorder characterized clinically by various combinations of myoclonus, epilepsy, cerebellar ataxia, choreoathetosis, dementia and psychiatric symptoms. Based on the phenomenon of anticipation, the gene for DRPLA was recently identified. DRPLA is caused by unstable expansion of a CAG repeat in the gene located on the short arm of chromosome 12. As have been observed in Huntington's disease and SCA1, there is a strong correlation between the age of onset and the size of CAG repeats. Furthermore, patients with larger repeats tend to show a PME (progressive myoclonus epilepsy) phenotype as well as earlier ages of onset. More prominent anticipation and larger intergenerational increase of CAG repeats in paternal transmission can be accounted for by the meiotic instability of CAG repeats in male gametogenesis. Comparison of size distributions of CAG repeats in Japanese, African-American and white populations revealed that 7.4% of the Japanese alleles had greater than 19 repeats, whereas none of the whites and 1% of the African-American alleles were of this size. The results may account for the ethnic predilection of DRPLA.

The most common autosomal recessive ataxia is Friedreich's ataxia (FA), characterized mainly by an early onset, absent tendon reflexes, deep sensory loss, cerebellar and Babinski signs. Screening the patients from families with classical FA features, we found that some families were excluded from the FA locus on chromosome 9, and are associated to isolate vitamin E deficiency. The similarity of the clinical data between FA with and without vitamin E deficiency was remarkable. The disorder with vitamin E deficiency often confused with FA, is currently known as linked to chromosome 8q. Therefore it is important to test vitamin E levels in all patients suspected to have FA, since the alpha tocopherol supplementation may be efficient in early stages of the disease.

Mendelian forms of benign myoclonic epilepsies where a chromosomal locus has been defined include (1) the autosomal dominant (AD) juvenile myoclonic epilepsy (JME) in chr. 6p11, (2) the autosomal dominant childhood absence epilepsy which evolves to JME in chr. 1p, (3) familial adult myoclonic epilepsy of Yasuda and Inazuki, and (4) possibly JME within the idiopathic generalized epilepsy susceptibility gene in chr. 8 reported by Zara et al (1995). Other myoclonic epilepsy syndromes with onset in the first year of life (Aicardi's Neonatal (Early) Myoclonic Encephalopathy, West's Syndrome, Dravet's Severe Myoclonic Epilepsy, and Dravet's Benign Myoclonic Epilepsy of Infancy), in early childhood (Lennox-Gastaut-Dravet Syndrome, Myoclonic Variant of Lennox Gastaut Dravet Syndrome, Myoclonic-Astatic Epilepsy of Doose, Benign Myoclonic Epilepsies (BME), or even in late childhood (Childhood Absence Epilepsy with myoclonias, vs. Myoclonic Absence Epilepsy) are probably genetically complex diseases. Amongst the progressive myoclonus epilepsy syndromes, specific mutations have already been defined in Unverricht Lundborg disease, ceroid lipofuscinoses 3 or Spielmayer Voight syndrome within Battens disease, sialidosis, dentadorubropallidoluysian atrophy and the mitochondrial syndrome MERRF. Most recently our laboratories established the locus for Lafora's disease in chr. 6q and results are speedily moving towards the definition of its mutation.

The discovery of major neurodegenerative mechanisms has opened the way to the development of novel therapeutic approaches. Gene therapy now enables researchers to overcome certain problems inherent to pharmacotherapy and to the grafting of embryonic cells. The production of recombinant adenoviruses are promising for in vivo gene therapy involving neuroprotective (Ad-SOD), neurotrophic (Ad-NGF) as well as restorative (Ad-TH) strategies. In addition, human neural progenitors offer great potential as vehicles for ex vivo gene therapy to replace degenerated cells in advanced stages of neurodegenerative diseases. This paper describes the clinical values of the new generations of adenoviral vectors.