A scoping review of the relationship between alcohol, memory consolidation and ripple activity: An overview of common methodologies to analyse ripples.

Alcohol abuse is not only responsible for 5.3% of the total deaths in the world but also has a substantial impact on neurological and memory disabilities throughout the population. One extensively studied brain area involved in cognitive functions is the hippocampus. Evidence in several rodent models has shown that ethanol produces cognitive impairment in hippocampal-dependent tasks and that the damage is varied according to the stage of development at which the rodent was exposed to ethanol and the dose. To the authors' knowledge, there is a biomarker for cognitive processes in the hippocampus that remains relatively understudied in association with memory impairment by alcohol administration. This biomarker is called sharp wave-ripples (SWRs) which are synchronous neuronal population events that are well known to be involved in memory consolidation. Methodologies for facilitated or automatic identification of ripples and their analysis have been reported for a wider bandwidth than SWRs. This review is focused on communicating the state of the art about the relationship between alcohol, memory consolidation and ripple activity, as well as the use of the common methodologies to identify SWRs automatically.

An update of 4­aminopyride as a useful model of generalized seizures for testing antiseizure drugs: in vitro and in vivo studies.

Aminopyridines constitute a drug family with the ability to enhance synaptic transmission. In particular, 4­aminopyridine (4­AP) has been used as a model of generalized seizures. 4­AP is a K+ channel blocker, but its mechanism of action has not yet been fully described; some evidence has shown that it acts on the K+ channel types Kv1.1, Kv1.2, Kv1.4 and Kv4, which are localized in the axonic terminals of pyramidal neurons and interneurons. When 4­AP blocks the K+ channels it triggers depolarization and prolongs the action potential in the neuron, which causes nonspecific neurotransmitter release. Among these neurotransmitters, glutamate is the principal excitatory neurotransmitter released in the hippocampus. Once glutamate is released, it reaches its ionotropic and metabotropic receptors continuing the neuronal depolarization chain and propagation of hyperexcitability. This brief review is focused on the use of 4­AP as an effective seizure model for testing antiseizure drugs in relevant in vitro and in vivo studies.

Validación de un instrumento para medir el respeto de la autonomía del paciente en situación terminal durante la toma de decisiones médicas sobre el final de la vida / Validació d'un instrument per mesurar el respecte de l'autonomia del pacient en situació terminal durant la presa de decisions mèdiques sobre el final de la vida / Validation of an instrument to measure respect for the autonomy of terminally ill patients during end-of-life medical decision-making

Antecedentes: El respeto por la autonomía de la persona consiste en considerarlas preferencias y valores de la persona enferma durante la toma de decisions sobre el tipo de atención que recibe y es un elemento bioético-jurídico. Sin embargo, no existen instrumentos validados sobre este fenómeno que ayuden aclarificar la percepción del médico sobre este principio.Objetivo: Elaborar, validar mediante juicio de expertos y pilotear para obtener la consistencia interna de un instrumento que evalúa el nivel de acuerdo de los médicos sobre los diferentes elementos que constituyen el respeto por la autonomía de la persona enferma en etapa terminal.Métodos: Estudio transversal. Método de validación por juicio de diez expertos de México. El instrumento se piloteó en médicos de un hospital público de alta especialidad para determinar la consistencia interna del mismo.Resultados: Se generó un instrumento de 15 ítems con un índice de validez de contenido de 0.82 para 10 expertos. Fue piloteado en una muestra de 96 médicos. Se obtuvo un alfa de Cronbach de 0.694.Conclusiones: Se desarrolló, validó y evaluó la consistencia interna de un cuestionario para medir el nivel de acuerdo de médicos que atienden a persones enfermas en etapa terminal con relación a los aspectos constitutivos sobre el respeto de su autonomía. Se recomienda su aplicación en médicos para corroborar su utilidad y favorecerun diagnóstico situacional sobre la situación estudiada.(AU)

Antecedents: El respecte per l'autonomia de la persona consisteix a considerar-les preferències i valors de la persona malalta durant la presa de decisions sobre el tipus d'atenció que rep i és un element bioeticojurídic. No obstant això, no hi ha instruments validats sobre aquest fenomen que ajudin a aclarir la percepció del metge sobreaquest principi.Objectiu: Elaborar, validar mitjançant un judici d'experts i pilotejar per obtenir la consistència interna d'un instrument que avalua el nivell d'acord dels metges sobre els diferents elements que constitueixen el respecte per l'autonomiade la persona malalta en l'etapa terminal.Mètodes: Estudi transversal. Mètode de validació per judici de deu experts de Mèxic. L'instrument es va pilotejar en metges d'un hospital públic d'alta especialitat per determinar-ne la consistència interna.Resultats: Es va generar un instrument de 15 ítems amb un índex de validesa de contingut de 0.82 per a 10 experts. Va ser pilotejat en una mostra de 96 metges. S'obtingué un alfa de Cronbach de 0.694.Conclusions: Es va desenvolupar, validar i avaluar la consistència interna d'un qüestionari per mesurar el nivell d'acord de metges que atenen persones malaltes en etapa terminal amb relació als aspectes constitutius sobre el respecte de la seva autonomia. Se'n recomana l'aplicació en metges per corroborar-ne la utilitat i afavorir un diagnòstic situacional sobre la situació estudiada.(AU)

Background: Respect for the autonomy of the person consists in considering the preferences and values of the sick person when making decisions about the type of care they receive and is a bioethical-legal element. However, there are no validated instruments on this phenomenon that help to clarify the physician's perception of this principle.Objective: To elaborate, validate through expert judgment and determine the internal consistency of an instrument that evaluates the level of agreement that the doctors have on the different elements that constitute respect for theautonomy of the terminally ill person.Methods: Cross-sectional study. The expert judgment validation method was used with a panel of ten experts from Mexico. The instrument was piloted in doctors of a highly specialized public hospital to determinate itsinternal consistency.Results: An instrument of 15 items was generated with a content validity index of 0.82 for 10 experts. It was piloted in a sample of 96 doctors (31.3% female and 68.7% male) and with an average age of 30 years. The Cronbach's alpha was 0.694.Conclusions: A questionnaire was developed to measure the level of agreement that the doctor who cares for terminally ill people has in relation to the constitutive aspects of respect for their autonomy. Based on the results of the validation andinternal consistency, its application in medical populations is recommended to corroborate its usefulness and favoura simple situational diagnosis of the situation studied.(AU)

Allopurinol and ellagic acid decrease epileptiform activity and the severity of convulsive behavior in a model of status epilepticus.

BACKGROUND: During status epilepticus, severe seizures can occur, generating recurrent cycles of excitotoxicity and oxidative stress that cause neuronal damage and cell death. The administration of agents with antioxidant properties represents a therapeutic alternative aimed at reducing the severity of status epilepticus and mitigating the neurobiological consequences that precede them. OBJECTIVE: The objective of this work was to evaluate the antiseizure effect of the antioxidants allopurinol (ALL) and ellagic acid during status epilepticus induced by pilocarpine (PILO). METHODS: Male Wistar rats (200-250 g) were injected with ALL (50 mg/kg) or ellagic acid (50 mg/kg), 30 min before PILO administration (pretreatment) or 60 min after the beginning of status epilepticus, to evaluate the antiseizure effect of these drugs on epileptiform activity and convulsive behavior. RESULTS: ALL or ellagic acid administration before or after PILO significantly decreased the epileptiform activity and the severity of convulsive behavior. Better efficacy was observed when the drugs were administered as a pretreatment, increasing the latency time of the appearance of status epilepticus from 27.2 ± 2.6 to 45.8 ± 3.31 min, and significantly reducing the amplitude of epileptiform discharges by 53.5% with ALL and 68.9% with ellagic acid. CONCLUSION: The antioxidants ALL and ellagic acid showed an antiseizure effect, representing an alternative to reduce epileptiform activity and severity of convulsive behavior during status epilepticus, an effect that may be used as adjuvants to mitigate or reduce oxidative damage processes.

A novel hydro-pneumatic fluid percussion device for inducing traumatic brain injury: assessment of sensory, motor, cognitive, molecular, and morphological outcomes in rodents.

Introduction: The fluid percussion method is widely used to induce brain injury in rodents. However, this approach has several limitations, including variability in the resulting damage, which is attributed to factors such as manual control of the mass used to generate the desired pressure. To address these issues, several modifications to the original method have been proposed. Methods: In this study, we present a novel device called the Hydro-pneumatic Fluid Percussion Device, which delivers fluid directly to a lateral region of the brain to induce injury. To validate this model, three groups of male and female rats were subjected to lateral fluid percussion using our device, and the resulting damage was evaluated using sensory, motor, and cognitive tests, measurements of serum injury biomarkers, and morphological analysis via cresyl violet staining. Results: Our results demonstrate that this new approach induced significant alterations in all parameters evaluated. Discussion: This novel device for inducing TBI may be a valuable alternative for modeling brain injury and studying its consequences.

Ellagic acid and allopurinol decrease H2O2 concentrations, epileptiform activity and astrogliosis after status epilepticus in the hippocampus of adult rats.

Status epilepticus (SE) can result in an overproduction of hydrogen peroxide (H2O2), which contributes to oxidative stress and brain injury during different phases of epileptogenesis and seizures. The purpose of this study was to evaluate the effects of ellagic acid and allopurinol administered after SE on H2O2 concentrations, electrical activity and GFAP immunoreactivity in the hippocampus of rats evaluated on Day 18 after SE. H2O2 levels were measured using an online technique with high temporal resolution and simultaneous electrical activity recording. For this purpose, the lateral ventricles of male Wistar rats (200-250 g) were injected with pilocarpine (2.4 mg/2 µl) to induce SE. After SE, rats were injected with ellagic acid (50 mg/kg i.p., and two additional doses at 24 and 48 h) or allopurinol (50 mg/kg i.p., single dose). Administration of ellagic acid or allopurinol after SE significantly reduced the H2O2 concentrations and decreased the presence of epileptiform activity and GFAP immunoreactivity in the hippocampus 18 days after SE. In conclusion, the administration of antioxidants potentially reduces oxidative stress, which indicates the possible attenuation of the neurobiological consequences after SE.

Causal relationship of CA3 back-projection to the dentate gyrus and its role in CA1 fast ripple generation.

BACKGROUND: Pathophysiological evidence from temporal lobe epilepsy models highlights the hippocampus as the most affected structure due to its high degree of neuroplasticity and control of the dynamics of limbic structures, which are necessary to encode information, conferring to it an intrinsic epileptogenicity. A loss in this control results in observable oscillatory perturbations called fast ripples, in epileptic rats those events are found in CA1, CA3, and the dentate gyrus (DG), which are the principal regions of the trisynaptic circuit of the hippocampus. The present work used Granger causality to address which relationships among these three regions of the trisynaptic circuit are needed to cause fast ripples in CA1 in an in vivo model. For these purposes, male Wistar rats (210-300 g) were injected with a single dose of pilocarpine hydrochloride (2.4 mg/2 µl) into the right lateral ventricle and video-monitored 24 h/day to detect spontaneous and recurrent seizures. Once detected, rats were implanted with microelectrodes in these regions (fixed-recording tungsten wire electrodes, 60-µm outer diameter) ipsilateral to the pilocarpine injection. A total of 336 fast ripples were recorded and probabilistically characterized, from those fast ripples we made a subset of all the fast ripple events associated with sharp-waves in CA1 region (n = 40) to analyze them with Granger Causality. RESULTS: Our results support existing evidence in vitro in which fast ripple events in CA1 are initiated by CA3 multiunit activity and describe a general synchronization in the theta band across the three regions analyzed DG, CA3, and CA1, just before the fast ripple event in CA1 have begun. CONCLUSION: This in vivo study highlights the causal participation of the CA3 back-projection to the DG, a connection commonly overlooked in the trisynaptic circuit, as a facilitator of a closed-loop among these regions that prolongs the excitatory activity of CA3. We speculate that the loss of inhibitory drive of DG and the mechanisms of ripple-related memory consolidation in which also the CA3 back-projection to DG has a fundamental role might be underlying processes of the fast ripples generation in CA1.

Increased immunoreactivity of glutamate receptors, neuronal nuclear protein and glial fibrillary acidic protein in the hippocampus of epileptic rats with fast ripple activity.

Epilepsy is a neurological disorder in which an imbalance between excitatory and inhibitory transmission is observed. Glutamate is the principal excitatory neurotransmitter that acts through ionic and metabotropic receptors; both types of receptors are involved in temporal lobe epilepsy (TLE). High frequency oscillations called fast ripples (FR, 250-600 Hz) have been observed, particularly in the hippocampus, and they are involved in epileptogenesis. The present study analyzed the immunoreactivity of the principal glutamate receptors associated with epilepsy in epileptic animals with FR activity. Male Swiss-Wistar rats (210-250 gr) were injected with pilocarpine (2.4 mg/2 µl) and were video monitored (24/7) until the appearance of spontaneous and recurrent seizures. Then, a deep microelectrode implantation surgery was performed in the DG, CA3 and CA1 regions, and FR activity was observed 1-, 2-, 3-, 7-, and 14-day postsurgery. The animals were sacrificed on day 15, and fluorescence immunohistochemistry was carried out in the hippocampus for the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA) and mGlu-R5 glutamate receptors as well as Neuronal Nuclear Protein (NeuN) and Glial Fibrillary Acidic Protein (GFAP). An increase in the immunoreactivity for the three receptors was found. However, the AMPA receptor showed an increase in the three regions analyzed (i.e., DG, CA1 and CA3). The findings showed a decrease of NeuN in the DG and an increase of GFAP. These results suggest an important role of glutamate receptors in the hippocampus of epileptic rats with FR activity.

Nano dot blot: An alternative technique for protein identification and quantification in a high throughput format.

BACKGROUND: Dot blot technique has been used in a similar way to western blotting, with the major difference being the lack of protein separation with electrophoresis. Protein samples are spotted over a membrane paper, the identification and quantification of a protein is achieved by immunodetection procedures such as colorimetry, fluorescence or chemiluminescence. This technique is widely accepted, but it uses large amounts of sample and antibodies to reveal the presence of the target protein. Significant milestones have been reached to achieve better results with the use of less sample and reagents; however, the ninety-six-well format is still in use. NEW METHOD: In this work, we propose an innovation to this technique, reducing the amount of sample and antibodies to identify a specific protein when compared to the regular dot blot method. Procedure consists of using a sample volume of approximately 200 nanoliters deposited with a multineedle device developed by our group. RESULTS: Five samples of standard protein or antigen can be spotted in a Cartesian format to identify and quantify the protein involved in physiological or pathological conditions. In addition, at least five replicates of sample or antigen are used to enable better statistics to calculate the concentration of every standard and the protein present in a sample. CONCLUSIONS: Hundreds of samples can be deposited in a few minutes and analyzed in a single experimental session. To validate this method, which we called nano dot blot, six proteins involved in the inflammation process were tested in acute and chronic rat models of seizures.

Evaluation of the hippocampal immunoreactivity of the serotonin 5-HT1A, 5-HT2 and 5-HT7 receptors in a pilocarpine temporal lobe epilepsy rat model with fast ripples.

Fast ripples (FRs) are found in the hippocampus of epileptic brains, and this fast electrical activity has been described as a biomarker of the epileptogenic process itself. Results from our laboratory, such as the observation of decreased seizure rates and FR incidence at a specific citalopram dose, have suggested that serotonin (5-HT) may play a key role in the FR generation process. Therefore, to gather more details about the state of the serotoninergic system in the hippocampus under an epileptogenic process, we studied the immunoreactivity of three 5-HT receptors (5-HT1A, 5-HT2 and 5-HT7) as well as the extracellular levels of 5-HT in the hippocampal tissue of epileptic rats with FR. Wistar rats (210-300 g) were injected with a single dose of pilocarpine hydrochloride (2.4 mg/2 µl) in the right lateral ventricle and video-monitored 24 h/d to detect spontaneous and recurrent seizures; microelectrodes were implanted in the dentate gyrus (DG) and CA3 and CA1 regions of these rats ipsilateral to the pilocarpine injection site 1 day after the first spontaneous seizure was observed, and only rats who suffered FR events were used in this work. Thirty-three days after the first spontaneous seizure, an immunostaining procedure and high performance liquid chromatography were performed to measure the 5-HT levels. A general depletion of the 5-HT and 5-HIIA levels in hippocampal tissue from epileptic animals compared with those in controls was observed; in addition, a general decrease in immunoreactivity for the three receptors was found, especially in the DG, which may support the establishment of an excitatory/inhibitory imbalance in the trisynaptic circuit that underlies the FR generation process.