Effects of paradoxical sleep deprivation on the performance of rats in a model of visual attention

In the present work we sought to evaluate the effects of paradoxical sleep deprivation (PSD) on the performance of rats in the five-choice serial reaction time task, a test designed to assess attentional function. Adult male Wistar rats were trained to detect a brief (1 s) light stimulus randomly presented in one of five locations in a box specially designed for the task. After achieving stable performance, the animals were submitted to 96 h of sleep deprivation by the platform technique, in which the rats are placed on top of small platforms in a tank filled with water. During sleep, particularly during the paradoxical stage, the loss of muscle tone make the animals fall into the water, thus awakening them and so depriving of sleep. Performance in the task was assessed daily during the 96 h deprivation period and also during seven recovery days afterwards. Paradoxical sleep deprivation reduced accuracy on the on the third (72 h) and fourth (96 h) days of sleep deprivation compared to home-cage controls, and this impairment reverted soon after the beginning of the recovery period. Sleep-deprived animals also showed an increase in omissions in the first day of PSD and a reduction on the number of trials started on the fourth day of sleep deprivation. No significant group differences were observed in premature and perseverative responses, correct response latency and reward latency. Our results thus indicate that paradoxical sleep deprivation impairs attentional function.     

Clock gene polymorphisms and narcolepsy in positive and negative HLA-DQB1*0602 patients

Narcolepsy is a chronic sleep disorder. It is linked to the HLA-DQB1*0602 allele. A recent report established a genetic linkage between narcolepsy and the chromosomal region 4p13-q21 that contains the Clock gene. We studied two SNPs in the Clock gene aiming to find any association with narcolepsy. We did not find differences in genetic frequencies in the patients group. We concluded that these two SNPs are not associated with narcolepsy.     

Electrophysiological properties of cultured hippocampal neurons from Wistar Audiogenic Rats

The main goal of this work was to analyze the electrophysiological properties of cultured hippocampal neurons from a particular epileptic rat strain, called Wistar Audiogenic Rats (WAR). The whole-cell patch-clamp technique was used to record both active and passive membrane responses in an attempt to detect alterations in their characteristics in relation to controls from Wistar rats. Neurons from WARs show a significant reduction in the magnitude of the inhibitory GABAergic currents ( approximately 45%), in spite of maintaining a normal level of the excitatory glutamatergic currents. In addition, the magnitude of potassium currents, measured at +80 mV, is reduced by about 30% in comparison to controls. Surprisingly, we also found important changes in the passive cellular properties in WAR neurons such as membrane potential (-50.0 mV in WARs and -63.1 mV in controls) and input resistance (647 MOmega in WARs and 408 MOmega in controls). The changes described here, could be the basis of the neurophysiological and behavioral alterations present in these hyperexcitable animals, contributing to a better understanding of epileptogenesis in this particular animal model.     

Leprosy: contribution of mast cells to epineurial collagenization

BACKGROUND: Leprosy, a disease caused by Mycobacterium leprae, is an important health problem worldwide. It is responsible for an irreversible nerve damage in which fibrosis plays an important role. The existence of an interaction between mast cells and different fibrotic conditions has long been observed. Tryptase, the most abundant protein product of human mast cells, has been shown to be mitogenic for fibroblasts and to increase type I collagen production. PATIENTS AND METHODS: In order to explore the possible relationship between tryptase-rich mast cells and nerve fibrosis in leprosy, we studied 24 sural nerve biopsies of patients with leprous neuropathy. Mast cells stained with mouse antihuman mast cell antitryptase clone AA1 as well as fibrosis, were quantitatively estimated in both epi- and endoneurial compartments. RESULTS: There was a remarkable association between collagen increase and tryptase-rich mast cell density in the epineurium but not in the endoneurium of leprous nerves. CONCLUSION: Since the epineurium in leprosy is type I collagen rich, the present findings support a tryptase-rich mast cell contribution to epineurial collagenization in leprosy through their tryptase secretion.     

Botulinum toxin type A for the treatment of the upper limb spasticity after stroke: a meta-analysis

Muscle over-activity is one of the cardinal features of spasticity and it is a common disability of stroke patients. In this group, spasticity is responsible for several limitations that interfere in their daily activities and quality of life. To treat spasticity, neurologists usually prescribe drugs as baclofen, tizanidine or benzodiazepines or even use definitive treatment as phenol or surgery. Authors suggest the use of botulinum toxin type A (BTX-A) for spasticity in the upper limbs after stroke, but there are few papers with adequate methodology supporting this idea. In this article we summarize the data of previous double-blind, randomised clinical trials to asses, with a meta-analysis, if BTX-A is an adequate treatment for spasticity due to stroke. The results show a statistical superiority of BTX-A ov%r placebo on reducing muscle tone by the Modified Ashworth Scale (WMD= 0.95 [0.74 to 1.17]) in patients with post-stroke upper limb spasticity.     

Craniotomy guided by computed tomography with three dimensional reconstruction: technical note

OBJECTIVE: Searching usefulness of computed tomography with three dimensional reconstruction in planning accurate cranial approaches to treat subcortical lesions. METHOD: Eight patients with neoplastic subcortical convexity-based lesions were surgically treated following spatial coordination obtained with three dimensional computed tomography reconstruction (CT 3D). RESULTS: Accurate approaches were accomplished, allowing a safe and optimized removal of neoplasms in all cases. CONCLUSION: The study manifests the benefits of CT 3D in planning suitable craniotomies, avoiding incongruous approaches.     

Pitfalls in the clinical and electroencephalographic diagnosis of ceroid lipofuscinosis

Neuronal ceroid lipofuscinosis (NCL) were traditionally classified according to age of onset and clinical features in four main groups. Recently, a combination of clinical, ultra structural and genetics data led to the recognition of eight forms of NCL, providing a more precise framework to classify atypical cases. By the other hand, it was shown that mutations in the same gene could be responsible for a large variety of clinical phenotypes. The objective of this study is to describe two brothers with clinical and electroencephalographic abnormalities characteristic of juvenile NCL, but with ultra structural abnormalities suggestive of late infantile NCL. Electroencephalogram is useful for clinical diagnosis of NCL but it is not helpful in its classification.     

Mitochondrial dysfunction in autism spectrum disorders: a population-based study

A minority of cases of autism has been associated with several different organic conditions, including bioenergetic metabolism deficiency. In a population-based study, we screened associated medical conditions in a group of 120 children with autism (current age range 11y 5mo to 14y 4mo, mean age 12y 11mo [SD 9.6mo], male:female ratio 2.9:1). Children were diagnosed using Diagnostic and Statistical Manual of Mental Disorders criteria, the Autism Diagnostic Interview--Revised, and the Childhood Autism Rating Scale; 76% were diagnosed with typical autism and 24% with atypical autism. Cognitive functional level was assessed with the Griffiths scale and the Wechsler Intelligence Scale for Children and was in the normal range in 17%. Epilepsy was present in 19 patients. Plasma lactate levels were measured in 69 patients, and in 14 we found hyperlactacidemia. Five of 11 patients studied were classified with definite mitochondrial respiratory chain disorder, suggesting that this might be one of the most common disorders associated with autism (5 of 69; 7.2%) and warranting further investigation.     

Antiepileptic effect of acylpolyaminetoxin JSTX-3 on rat hippocampal CA1 neurons in vitro

The Joro spider toxin (JSTX-3), derived from Nephila clavata, has been found to block glutamate excitatory activity. Epilepsy has been studied in vitro, mostly on rat hippocampus, through brain slices techniques. The aim of this study is to verify the effect of the JSTX-3 on the epileptiform activity induced by magnesium-free medium in rat CA1 hippocampal neurons. Experiments were performed on hippocampus slices of control and pilocarpine-treated Wistar rats, prepared and maintained in vitro. Epileptiform activity was induced through omission of magnesium from the artificial cerebrospinal fluid (0-Mg2+ ACSF) superfusate and iontophoretic application of N-methyl-D-aspartate (NMDA). Intracellular recordings were obtained from CA1 pyramidal neurons both of control and epileptic rats. Passive membrane properties were analyzed before and after perfusion with the 0-Mg2+ ACSF and the application of toxin JSTX-3. During the ictal-like activity, the toxin JSTX-3 was applied by pressure ejection, abolishing this activity. This effect was completely reversed during the washout period when the slices were formerly perfused with artificial cerebrospinal fluid (ACSF) and again with 0-Mg2+ ACSF. Our results suggest that the toxin JSTX-3 is a potent blocker of induced epileptiform activity.