Intense training prevents the amnestic effect of inactivation of dorsomedial striatum and induces high resistance to extinction.

A large body of evidence has shown that treatments that interfere with memory consolidation become ineffective when animals are subjected to an intense learning experience; this effect has been observed after systemic and local administration of amnestic drugs into several brain areas, including the striatum. However, the effects of amnestic treatments on the process of extinction after intense training have not been studied. Previous research demonstrated increased spinogenesis in the dorsomedial striatum, but not in the dorsolateral striatum after intense training, indicating that the dorsomedial striatum is involved in the protective effect of intense training. To investigate this issue, male Wistar rats, previously trained with low, moderate, or high levels of foot shock, were used to study the effect of tetrodotoxin inactivation of dorsomedial striatum on memory consolidation and subsequent extinction of inhibitory avoidance. Performance of the task was evaluated during seven extinction sessions. Tetrodotoxin produced a marked deficit of memory consolidation of inhibitory avoidance trained with low and moderate intensities of foot shock, but normal consolidation occurred when a relatively high foot shock was used. The protective effect of intense training was long-lasting, as evidenced by the high resistance to extinction exhibited throughout the extinction sessions. We discuss the possibility that increased dendritic spinogenesis in dorsomedial striatum may underly this protective effect, and how this mechanism may be related to the resilient memory typical of post-traumatic stress disorder (PTSD).

Steering the Microbiota-Gut-Brain Axis by Antibiotics to Model Neuro-Immune-Endocrine Disorders.

BACKGROUND: Over the last century, animal models have been employed to study the gut-brain axis and its relationship with physiological processes, including those necessary for survival, such as food intake and thermoregulation; those involved in diseases, ranging from inflammation to obesity; and those concerning the development of neurodegenerative diseases and neuropsychiatric disorders, such as Alzheimer's disease and autism spectrum disorder, respectively. SUMMARY: The gut microbiota has been recognized in the last decade as an essential functional component of this axis. Many reports demonstrate that the gut microbiota influences the development of a vast array of physiological processes. Experiments that use animal models to assess the effect of the gut microbiota on the brain and behavior may involve the acute or chronic administration of broad-spectrum antibiotics. KEY MESSAGES: This narrative review summarizes the beneficial or detrimental effects of antibiotics administered prenatally or postnatally to rodents during acute or chronic periods in a wide range of protocols. These include animal models of disease and behavioral paradigms of learning and memory, anxiety, obsessive-compulsive disorder, and autism spectrum disorder. Biomarkers and behavioral assays associated with antibiotic exposure are also included in this review.

Hepatocyte ballooning and steatosis in early and late gestation without liver malfunction: Effects of low protein/high carbohydrate diet.

Pregnancy is a challenging metabolic and physiological condition. The aim of this study was to include a second demanding situation as a low protein/high carbohydrate diet (LPHCD) to characterize the histological and functional responses of the maternal liver. It is unknown how the maternal liver responds during early and late pregnancy to LPHCD intake. We explored early pregnancy (3 and 8 gestational age, G) and late pregnancy (15 and 20 G). The results indicated that pregnant rats under control diet showed an evident presence of ballooned hepatocytes, lipid vesicles and edema at late pregnancy (15G); in contrast, pregnant rats under LPHCD showed similar pattern of histological modification but at early pregnancy (3G). Unexpectedly, the serum biomarkers didn't display functional alterations in either group, despite of the evident histological changes no liver malfunction was detected. We conclude that pregnant rats fed with control diet and experimental LPHCD, are subjected to metabolic and physiological conditions that impact the histopathological condition of the maternal liver. Control diet promoted the histological modifications during late pregnancy whereas LPCHCD advanced the onset of these changes. Further experiments are needed to explore the biochemical mechanisms that underlie these histological modifications. Our results are also an example of the resilience associated with the pregnancy: since no functional hepatic alterations accompanied the histopathological changes, another conclusion is that no evident pathological condition was detected in this nutritional protocol.

Investigating the Electrochemically Driven Capture and Release of Long-Chain PFAS by Redox Metallopolymer Sorbents.

The remediation of perfluoroalkyl substances (PFAS) is an urgent challenge due to their prevalence and persistence in the environment. Electrosorption is a promising approach for wastewater treatment and water purification, especially through the use of redox polymers to control the binding and release of target contaminants without additional external chemical inputs. However, the design of efficient redox electrosorbents for PFAS faces the significant challenge of balancing a high adsorption capacity while maintaining significant electrochemical regeneration. To overcome this challenge, we investigate redox-active metallopolymers as a versatile synthetic platform to enhance both electrochemical reversibility and electrosorption uptake capacity for PFAS removal. We selected and synthesized a series of metallopolymers bearing ferrocene and cobaltocenium units spanning a range of redox potentials to evaluate their performance for the capture and release of perfluorooctanoic acid (PFOA). Our results demonstrate that PFOA uptake and regeneration efficiency increased with more negative formal potential of the redox polymers, indicating possible structural correlations with the electron density of the metallocenes. Poly(2-(methacryloyloxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate) (PMAECoPF6) showed the highest affinity toward PFOA, with an uptake capacity of more than 90 mg PFOA/g adsorbent at 0.0 V vs Ag/AgCl and a regeneration efficiency of more than 85% at -0.4 V vs Ag/AgCl. Kinetics of PFOA release showed that electrochemical bias greatly enhanced the regeneration efficiency when compared to open-circuit desorption. In addition, electrosorption of PFAS from different wastewater matrices and a range of salt concentrations demonstrated the capability of PFAS remediation in complex water sources, even at ppb levels of contaminants. Our work showcases the synthetic tunability of redox metallopolymers for enhanced electrosorption capacity and regeneration of PFAS.

Intense inhibitory avoidance training increases nuclear-phosphorylated glucocorticoid receptors in neurons of CA1 of hippocampus and ventral caudate putamen.

Corticosterone (CORT), the principal glucocorticoid in rodents, is released after stressful experiences such as training with high foot-shock intensities in the inhibitory avoidance task (IA). CORT reaches the glucocorticoid receptor (GR) located in almost all brain cells; the GR is subsequently phosphorylated at serine 232 (pGRser232). This has been reported as an indicator of ligand-dependent activation of the GR, as well as a requirement for its translocation into the nucleus for its transcription factor activity. The GR is present in the hippocampus with a high concentration in CA1 and dentate gyrus (DG), and a smaller proportion in CA3, and sparsely present in the caudate putamen (CPu); both structures are involved in memory consolidation of IA. To study the participation of CORT in IA, we quantified the ratio of pGR-positive neurons in both dorsal hippocampus (CA1, CA3 and DG) and dorsal and ventral regions of CPu of rats trained in IA, using different foot-shock intensities. Brains were dissected 60 min after training for immunodetection of pGRser232 positive cells. The results show that the groups trained with 1.0 and 2.0 mA had higher retention latencies than the 0.0 mA or 0.5 mA groups. An increase in the ratio of pGR-positive neurons was found in CA1 and ventral region of CPu only for the 2.0 mA trained group. These findings suggest that activation of GRs in CA1 and ventral CPu is involved in the consolidation of a stronger memory of IA, possibly through the modulation of gene expression.

Chronic-Antibiotics Induced Gut Microbiota Dysbiosis Rescues Memory Impairment and Reduces ß-Amyloid Aggregation in a Preclinical Alzheimer's Disease Model.

Alzheimer's disease (AD) is a multifactorial pathology characterized by ß-amyloid (Aß) deposits, Tau hyperphosphorylation, neuroinflammatory response, and cognitive deficit. Changes in the bacterial gut microbiota (BGM) have been reported as a possible etiological factor of AD. We assessed in offspring (F1) 3xTg, the effect of BGM dysbiosisdysbiosis in mothers (F0) at gestation and F1 from lactation up to the age of 5 months on Aß and Tau levels in the hippocampus, as well as on spatial memory at the early symptomatic stage of AD. We found that BGM dysbiosisdysbiosis with antibiotics (Abx) treatment in F0 was vertically transferred to their F1 3xTg mice, as observed on postnatal day (PD) 30 and 150. On PD150, we observed a delay in spatial memory impairment and Aß deposits, but not in Tau and pTau protein in the hippocampus at the early symptomatic stage of AD. These effects are correlated with relative abundance of bacteria and alpha diversity, and are specific to bacterial consortia. Our results suggest that this specific BGM could reduce neuroinflammatory responses related to cerebral amyloidosis and cognitive deficit and activate metabolic pathways associated with the biosynthesis of triggering or protective molecules for AD.

Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes.

The removal of per- or polyfluorinated alkyl substances (PFAS) has received increasing attention because of their extreme stability, our increasing awareness of their toxicity at even low levels, and scientific challenges for traditional treatment methods such as separation by activated carbon or destruction by advanced oxidation processes. Here, we performed a direct and systematic comparison of two electrified approaches that have recently shown promise for effective degradation of PFAS: plasma and conventional electrochemical degradation. We tailored a reactor configuration where one of the electrodes could be a plasma or a boron-doped diamond (BDD) electrode and operated both electrodes galvanostatically by continuous direct current. We show that while both methods achieved near-complete degradation of PFAS, the plasma was only effective as the cathode, whereas the BDD was only effective as the anode. Compared to the BDD, plasma required more than an order of magnitude higher voltage but lower current to achieve similar degradation efficiency with more rapid degradation kinetics. All these factors considered, it was noted that plasma or BDD degradation resulted in similar energy efficiencies. The BDD electrode exhibited zero-order kinetics, and thus, PFAS degradation using the conventional electrochemical method was kinetically controlled. On the contrary, analysis using a film model indicated that the plasma degradation kinetics of PFAS using plasma were mass-transfer-controlled because of the fast reaction kinetics. With the help of a simple quantitative model that incorporates mass transport, interfacial reaction, and surface accumulation, we propose that the degradation reaction kinetically follows an Eley-Rideal-type mechanism for the plasma electrode, and an intrinsic rate constant of 2.89 × 108 m4 mol-1 s-1 was obtained accordingly. The investigation shows that to realize the true kinetic potential of plasma degradation for water treatment, mass transfer to the interface must be enhanced.

Household composition after resettlement and emotional health in adolescent migrants.

Background: Migration during adolescence constitutes an important stressor that particularly impacts unaccompanied minors (UAM). Adolescent UAM in the United States (U.S.) are relatively understudied, especially regarding their resilience and emotional well-being after resettlement. Small school-based studies have documented the mental health status of UAM who resettled reuniting with their parents. However, many do not resettle with parents and less is known about the degree to which post-resettlement household composition impacts resilience and emotional well-being. Methods: Our goal was to examine how migration characteristics, supports, resilience, and emotional well-being vary by UAM resettlement household composition (reunification with parents, reunification with a non-parental family member, or living in a household not containing any family members). Using a mixed-methods (quantitative-qualitative) cross-sectional approach, we assessed 46 Latin American adolescent UAM to the U.S. who resettled into these three household types. Results: Youth experienced support differently by household type, influencing their strategies for adapting and coping post-resettlement, impacting their resilience (Kruskal Wallis-H 4.8; p<0.09) and emotional well-being (Kruskal Wallis 5.3; p<0.07). Youth living in households without relatives (n = 9) had lower resilience (Fisher's exact test p<0.002) and positive affect (Fisher's exact test p<0.003) and needed to expend greater efforts to mobilize social supports than youth living with parents (n = 22) or with non-parental family members (n = 15). Conclusion: The needs and coping abilities of UAM migrants vary with the composition of their immediate receiving environment, their post-resettlement household. Understanding differences associated with these household characteristics can guide interventions to maximize emotional health and resilience.

Dynamics of Dendritic Spines in Dorsal Striatum after Retrieval of Moderate and Strong Inhibitory Avoidance Learning.

In marked contrast to the ample literature showing that the dorsal striatum is engaged in memory consolidation, little is known about its involvement in memory retrieval. Recent findings demonstrated significant increments in dendritic spine density and mushroom spine counts in dorsal striatum after memory consolidation of moderate inhibitory avoidance (IA) training; further increments were found after strong training. Here, we provide evidence that in this region spine counts were also increased as a consequence of retrieval of moderate IA training, and even higher mushroom spine counts after retrieval of strong training; by contrast, there were fewer thin spines after retrieval. Similar changes in mushroom and thin spine populations were found in the ventral striatum (nucleus accumbens), but they were related to the aversive stimulation and not to memory retrieval. These results suggest that memory retrieval is a dynamic process which produces neuronal structural plasticity that might be necessary for maintaining or strengthening assemblies that encode stored information.

Spatial Memory and Gut Microbiota Alterations Are Already Present in Early Adulthood in a Pre-clinical Transgenic Model of Alzheimer's Disease.

The irreversible and progressive neurodegenerative Alzheimer's disease (AD) is characterized by cognitive decline, extracellular ß-amyloid peptide accumulation, and tau neurofibrillary tangles in the cortex and hippocampus. The triple-transgenic (3xTg) mouse model of AD presents memory impairment in several behavioral paradigms and histopathological alterations from 6 to 16 months old. Additionally, it seems that dysbiotic gut microbiota is present in both mouse models and patients of AD at the cognitive symptomatic stage. The present study aimed to assess spatial learning, memory retention, and gut microbiota alterations in an early adult stage of the 3xTg-AD mice as well as to explore its sexual dimorphism. We evaluated motor activity, novel-object localization training, and retention test as well as collected fecal samples to characterize relative abundance, alpha- and beta-diversity, and linear discriminant analysis (LDA) effect size (LEfSe) analysis in gut microbiota in both female and male 3xTg-AD mice, and controls [non-transgenic mice (NoTg)], at 3 and 5 months old. We found spatial memory deficits in female and male 3xTg-AD but no alteration neither during training nor in motor activity. Importantly, already at 3 months old, we observed decreased relative abundances of Actinobacteria and TM7 in 3xTg-AD compared to NoTg mice, while the beta diversity of gut microbiota was different in female and male 3xTg-AD mice in comparison to NoTg. Our results suggest that gut microbiota modifications in 3xTg-AD mice anticipate and thus could be causally related to cognitive decline already at the early adult age of AD. We propose that microbiota alterations may be used as an early and non-invasive diagnostic biomarker of AD.

Sunlight exposure in infancy decreases risk of sporadic retinoblastoma, extent of intraocular disease.

BACKGROUND: Prior ecologic studies suggest that UV exposure through sunlight to the retina might contribute to increased retinoblastoma incidence. AIMS: Our study objectives were (1) to examine the relationship between exposure to sunlight during postnatal retinal development (prior to diagnosis of sporadic disease) and the risk of retinoblastoma, and (2) to examine the relationship between sun exposure during postnatal retinal development, and the extent of disease among children with unilateral and bilateral retinoblastoma. METHODS AND RESULTS: We interviewed 511 mothers in the EpiRbMx case-control study about their child's exposure to sunlight during postnatal retinal cell division by examining three time periods prior to Rtb diagnosis coinciding with developmental stages in which outdoor activities vary. Weekly sun exposure was compared by age period, between unilateral (n = 259), bilateral (n = 120), and control (n = 132) children, accounting for two factors affecting UV exposure: residential elevation and reported use of coverings to shield eyes. For cases, association between sunlight exposure and clinical stage was examined by laterality at each age period. After adjusting for maternal education and elevation, sun exposure was lower in cases than controls in all three age periods especially during the first 6 months, and in children 12-23 months whose mothers did not cover their eyes when outdoors. In children diagnosed after 12 months of age, sun exposure during the second year of life (age 12-23 months) appeared inversely correlated (r = -0.25) with more advanced intraocular disease in bilateral Rtb children after adjusting for maternal education, residential elevation, and age of diagnosis (p < .09) consistent with effects of Vitamin D exposure on intraocular spread in earlier transgenic murine models of retinoblastoma, and suggesting potential chemopreventive strategies. CONCLUSION: Sun exposure in early childhood is protective for retinoblastoma and may decrease degree of intraocular spread in children with bilateral Rtb.

Perspectivas de pacientes y profesionales en torno al uso de medicinas alternativas y complementarias para el cuidado del cáncer: un estudio exploratorio / Perception of Alternative and Complementary Medicine for Cancer Care among Patients and Health Professionals: An Exploratory Study

Introducción: el uso de medicinas alternativas y complementarias (MAC) por pacientes oncológicos es una práctica extendida, generalmente por fuera del tratamiento principal. La falta de entendimiento entre percepciones de pacientes y profesionales puede derivar en problemas de comunicación con repercusión negativa en el cuidado. Objetivo: indagar por coincidencias y divergencias en la percepción de pacientes y profesionales frente al uso de MAC en el paciente oncológico. Métodos: estudio exploratorio con análisis interpretativo fenomenológico mediante grupos focales, usando dominios prestablecidos. Se realizó codificación manual independiente y, posteriormente, se agruparon los códigos para su interpretación. El agrupamiento fue triangulado con el equipo de investigación para generar categorías definitivas. Resultados: surgieron dos categorías: conceptualización y vivencia frente a MAC. Cada categoría incluye subcategorías similares (p. ej., denominaciones, uso de MAC) y diferenciales (p. ej. valoración, fundamentación), entre los dos grupos. La conceptualización reconoce cómo los participantes caracterizan la MAC y la vivencia identifica la forma y vías como se relacionan con la MAC. Conclusiones: pacientes y profesionales comparten inquietudes frente al uso de MAC, pero existen diferencias en lenguaje y expectativas frente a su uso. Para los pacientes el consejo médico es relevante pero no definitivo y la evidencia científica solo es relevante para los profesionales.

Imbalance in cerebral protein homeostasis: Effects on memory consolidation.

The long-standing hypothesis that memory consolidation is dependent upon de novo protein synthesis is based primarily on the amnestic effects of systemic administration of protein synthesis inhibitors (PSIs). Early experiments on mice showed that PSIs produced interference with memory consolidation that was dependent on the doses of PSIs, on the interval between drug injection and training, and, importantly, on the degree and duration of protein synthesis inhibition in the brain. Surprisingly, there is a conspicuous lack of information regarding the relationship between the duration of protein synthesis inhibition produced by PSIs and memory consolidation in the rat, one of the species most widely used to study memory processes. We found that, in the male rat, a single injection of cycloheximide, a commonly used PSI, produced a significant imbalance in protein homeostasis: an early inhibition of protein synthesis that lasted for at least one hour, followed by hyperproduction of proteins that lasted three days. We evaluated memory consolidation of inhibitory avoidance trained with either low or high intensity of foot-shock at the peaks of protein synthesis inhibition and protein hyperproduction. We found that, independent of the moment of training, the low-foot-shock groups showed amnesia, while the high-foot-shock groups displayed optimal memory performance. These results indicate that memory consolidation of relatively weak training is impaired by the inhibition or hyperproduction of protein synthesis, and that intense training overcomes this dysregulation of protein homeostasis allowing for memory formation probably through non-genomic mechanisms.

Morris water maze overtraining increases the density of thorny excrescences in the basal dendrites of CA3 pyramidal neurons.

The hippocampus plays a fundamental role in spatial learning and memory. Dentate gyrus (DG) granular neurons project mainly to proximal apical dendrites of neurons in the CA3 stratum lucidum and also, to some extent, to the basal dendrites of CA3 pyramidal cells in the stratum oriens. The terminal specializations of DG neurons are the mossy fibers (MF), and these huge axon terminals show expansion in the CA3 stratum oriens after the animals undergo overtraining in the Morris Water Maze task (MWM). However, to our knowledge there are no reports regarding the possible changes in density of post-synaptic targets of these terminals in the basal dendrites of CA3 neurons after overtraining in the MWM. The purpose of this work was to study the density of thorny excrescences (TE) and other dendritic spine types (stubby, thin, and mushroom) in the CA3 stratum oriens in animals overtrained in the MWM for three consecutive days and in animals trained for only one day. Seven days after MWM training, the animals were sacrificed, and their brains removed and processed for rapid Golgi staining to visualize the different types of dendritic protrusions. Our results revealed that the relative quantity of stubby, thin, and mushroom dendritic spines did not change, regardless of amount of training. However, a significant increase in the density of TE was detected in the overtrained animals. These results strongly suggest that spatial water maze overtraining induces an increased density of MF-TE connections, which might be functionally relevant for long-term spatial memory formation.

Inhibition of transcription and translation in dorsal hippocampus does not interfere with consolidation of memory of intense training.

Findings of several experiments indicate that many treatments that typically interfere with memory consolidation are ineffective in preventing or attenuating memory induced by intense training. As extensive evidence suggests that the consolidation of newly acquired memories requires gene expression and de novo protein synthesis the present study investigated whether intense training prevents consolidation impairment induced by blockers of mRNA and protein synthesis. Rats were given a single inhibitory training trial using a moderate (1.0 mA) or a relatively intense (2.0 mA) foot-shock. Bilateral hippocampal infusions of the mRNA synthesis blocker DRB (10, 40 or 80 ng/0.5 µL/hemisphere) or the protein synthesis inhibitor anisomycin (ANI), an inhibitor de novo protein synthesis (15.62, 31.25, or 62.50 µg/0.5 µL/hemisphere) were administered 15 min prior to training. Retention was measured at 30 min or 48 h following training. DRB and ANI impaired memory of moderate training in a dose-dependent manner without affecting short-term memory. In contrast, memory consolidation was not impaired in the groups trained with 2.0 mA. The findings showed that: (1) inhibitors of transcription and translation in the hippocampus impair the consolidation of memory of inhibitory avoidance learning induced by moderate levels of aversive stimulation and (2) blocking of mRNA and protein synthesis does not prevent the consolidation of memory induced by relatively high levels of aversive stimulation. These findings do not support the hypothesis that gene expression and de novo protein synthesis are necessary steps for long-term memory formation as memory was not impaired if intense foot-shock was used in training.

Effects of anisomycin infusions into the dorsal striatum on memory consolidation of intense training and neurotransmitter activity.

The most influential hypothesis about the neurobiological basis of memory consolidation posits that this process is dependent upon de novo protein synthesis. Strong support for this proposition has been provided by a multitude of experiments showing that protein synthesis inhibitors (PSIs) interfere with consolidation. However, this hypothesis has been challenged by the results of studies showing that PSIs also produce a host of side effects that, by themselves, could account for their amnestic effects. It has been demonstrated that amnestic treatments become innocuous when administered to animals that have been subjected to intense training in a variety of learning tasks. We now report that while infusion of anisomycin (ANI), a PSI, into the dorsal striatum (DS) impairs memory consolidation of inhibitory avoidance learning in response to moderate aversive stimuli, such impairment by ANI is overcome by application of an intense stimulus. We also confirmed that ANI induces inhibition of protein synthesis in the DS, as evidenced by a reduction of the activity-regulated cytoskeletal associated protein (Arc). We found, for the first time, that ANI also induces an increased concentration of serotonin in the DS, which, by itself, may account for the interference with memory consolidation. These findings suggest that de novo protein synthesis in the dorsal striatum is not necessary for the consolidation of intense emotionally arousing experiences. The possibility of a non-genomic-dependent mechanism of memory consolidation is discussed.

Síndrome de Burnout en estudiantes del posgrado de pediatría / Burnout Syndrome in Pediatric Posgraduate students

Antecedentes: El síndrome de Burnout (SB) o síndrome de desgaste profesional, descrito por primera vez en 1974 por el psiquiatra america-no Herbert Freudenberger, como "estado de fatiga o frustración que se produce por la dedi-cación a una causa, forma de vida o relación que no produce el esperado refuerzo". El objeti-vo del estudio fue identi car el síndrome de Burnout en estudiantes del posgrado de pedia-tría de la Universidad Nacional Autónoma de Honduras en el Valle de Sula, que rotaban por el Hospital Nacional Mario Catarino Rivas durante el período de junio 2014 hasta agosto 2016. Pacientes y Métodos: Se realizó un estu-dio cuantitativo, descriptivo, no experimental con los médicos residentes ya descritos. Los datos se obtuvieron de un cuestionario en el cual se evaluaron características sociodemo-grá cas, laborales y propias del síndrome de Burnout además se implementó el instrumen-to Maslach Burnout Inventory (MBI) adaptado al español el cual determina; cansancio emo-cional (CE), despersonalización (DP) y realiza-ción personal (RP), que se han clasi cado en tres niveles: bajo, medio y alto Resultados: Se encuestaron 43 residentes. El 70% (30) presen-tó cansancio emocional alto, 60% (26) tenía niveles altos de despersonalización y 37% (16) presentó niveles bajos de realización personal. Se encontró que el 58% (25) tenían síndrome de Burnout Incompleto, 7% (3) presento Bur-nout completo y 35% (15) no presento el síndrome. Conclusiones: Se determinó que existe el Síndrome de Burnout en los residen-tes de pediatría. El síndrome de Burnout incompleto fue la presentación más frecuente en más de la mitad de los estudiantes...(AU)

Inhibition of transcription and translation in the striatum after memory reactivation: Lack of evidence of reconsolidation.

It has been found that interference with neural activity after a consolidated memory is retrieved produces an amnestic state; this has been taken has indicative of destabilization of the memory trace that would have been produced by a process of reconsolidation (allowing for maintenance of the original trace). However, a growing body of evidence shows that this is not a reliable effect, and that it is dependent upon some experimental conditions, such as the age of the memory, memory reactivation procedures, the predictability of the reactivation stimulus, and strength of training. In some instances, where post-retrieval treatments induce a retention deficit (which would be suggestive of interference with reconsolidation), memory is rescued by simple passing of time or by repeated retention tests. We now report that post-training and post-retrieval inhibition of transcription and translation in dorsal striatum, a structure where both of these manipulations have not been studied, produce interference with consolidation and a transitory retention deficit, respectively. These results do not give support to the reconsolidation hypothesis and lead to the conclusion that the post-activation deficiencies are due to interference with retrieval of information.

Estudio in vitro de la erosión dental asociada al chimó / In vitro study of dental erosion associated to Chimo

Antecedentes: Chimó es el nombre en Venezuela de una sustancia viscosa de color negruzco, cuyo componente principal deriva de la hoja de tabaco. Su consumo se ha asociado a alteraciones sistémicas y patologías bucales. Objetivo: Identificar in vitro la erosión dental asociada a exposición al chimó. Métodos: Se seleccionaron 30 dientes, 10 control negativo, 10 control positivo y 10 grupo experimental que se expusieron a soluciones de saliva artificial, Coca-Cola® light y chimó respectivamente, durante 20 semanas. Se analizó clínicamente la superficie y el análisis ultraestructural se efectuó con microscopio electrónico de barrido. Resultados: Clínicamente, se evidenció cambio de color en el grupo control negativo; cambio de color y superficial y pérdida de brillo en el grupo control positivo; y cambio de color y superficial en el grupo experimental (p = 0,000). El análisis ultraestructural indica que el grupo control negativo no presentó alteraciones morfológicas en la superficie del esmalte. En la escala de valores de grabado ácido utilizada, el grupo control positivo fue tipo 4 y el grupo experimental mostró estructura adamantina erosionada con imágenes similares a los patrones de grabado tipo 3-4. En cuanto a la clasificación según su gravedad, el grupo experimental correspondió al grado 1, con pérdida de esmalte sin involucrar dentina. Conclusión: En las condiciones experimentales de este estudio, el chimó produjo pérdida de la superficie del esmalte tanto clínica como ultraestructuralmente, con patrones de erosión tipos 3 y 4 de la escala de valores del grabado ácido y grado 1 según su gravedad.

Background: In Venezuela, chimó is a blackish goo derived from tobacco leaf. Its consumption has been associated with systemic and oral diseases. Purpose: To identify in vitro dental erosion associated to chimó exposure. Methods: The sample consisted of 30 teeth that were assigned 10 to the negative control group, another 10 to the positive control group, and 10 to the experimental group, which were exposed respectively to artificial saliva, Coca-Cola® light, and chimó for 20 weeks. Tooth surfaces were analyzed clinically and structurally, the latter through scanning electron microscope. Results: Clinical observations showed surface color change in the negative control group; color change and surface gloss loss in the positive control group; color and surface changes in the experimental group (p = 0.000). Ultrastructural analysis showed no enamel surface alterations in the negative control group. Acid etching scale values were 4 for the positive control group and 3-4 for the experimental group. The latter had signs of enamel erosion. In terms of severity of damage, the experimental group was type 1, that is, enamel loss without involving dentin. Conclusion: Under these experimental conditions, chimó caused clinical and ultrastructural enamel surface loss with type 3-4 erosion patterns, and type 1 severity.