Dosimetry in cranial photobiomodulation therapy: effect of cranial thickness and bone density.

This research aims to examine the influence of human skull bone thickness and density on light penetration in PBM therapy across different wavelengths, focusing on how these bone characteristics affect the absorption of therapeutic light. Analyses explored the effect of skull bone density and thickness on light penetration in PBM, specifically using Low-Level Laser Therapy (LLLT) for efficacy prediction. Measurements of bone thickness and density were taken using precise tools. This approach emphasizes LLLT's significance in enhancing PBM outcomes by assessing how bone characteristics influence light penetration. The study revealed no significant correlation between skull bone density and thickness and light penetration capability in photobiomodulation (PBM) therapy, challenging initial expectations. Wavelengths of 405 nm and 665 nm showed stronger correlations with bone density, suggesting a significant yet weak impact. Conversely, wavelengths of 532 nm, 785 nm, 810 nm, 830 nm, 980 nm, and 1064 nm showed low correlations, indicating minimal impact from bone density variations. However, data variability (R2 < 0.4) suggests that neither density nor thickness robustly predicts light power traversing the bone, indicating penetration capability might be more influenced by bone thickness at certain wavelengths. The study finds that the effectiveness of photobiomodulation (PBM) therapy with bone isn't just based on bone density and thickness but involves a complex interplay of factors. These include the bone's chemical and mineral composition, light's wavelength and energy dose, treatment duration and frequency, and the precise location where light is applied on the skull.

Estandarización y evaluación del desempeño de un inmunoensayo para la detección de anticuerpos contra el dominio de unión a receptor de la proteína de espícula del virus SARS-CoV-2 / Establishment and performance evaluation of an immunoassay for the antibody detection against the receptor binding domain of the SARS-CoV-2 spike protein

Resumen Objetivo: Establecer un inmunoensayo semicuantitativo para la detección de anticuerpos contra el dominio de unión al receptor de la proteína de espícula del coronavirus del síndrome respiratorio agudo grave tipo 2 y la evaluación de su desempeño como herramienta de apoyo diagnóstico. Métodos: Se generó una proteína recombinante del dominio de unión a receptor de la proteína de espícula del coronavirus del síndrome respiratorio agudo grave tipo 2. Dicha proteína se empleó como sustrato antigénico en la estandarización de dos ensayos semicuantitativos por inmunoadsorción ligados a enzima para la detección de inmunoglobulinas M e inmunoglobulinas G humanas. Se utilizó un conjunto de muestras de suero positivas (n=129), provenientes de donantes voluntarios con infección previa por el virus SARS-CoV-2, confirmada mediante reacción en cadena de la polimerasa con transcriptasa reversa, y tomadas entre agosto de 2020 y noviembre de 2021. Además, se empleó un panel de muestras prepandémicas negativas (n=196) obtenidas antes de diciembre de 2019 para la evaluación del desempeño de los ensayos; se recibieron muestras múltiples seriadas de 99 donantes voluntarios para examinar la respuesta de la prueba ante la seroconversión y se estudió la posible asociación entre las seropositividades por coronavirus del síndrome respiratorio agudo grave tipo 2 y por el virus del dengue para la evaluación de reacciones cruzadas inespecíficas. Resultados: El ensayo de detección de inmunoglobulina G mostró 81.4 % de sensibilidad, 86.2 % de especificidad y valores predictivos positivos y negativos de 79.5 % y 87.6 % respectivamente. Por su parte, el ensayo de detección de inmunoglobulina M mostró solamente 72.1 % de sensibilidad, 54.1 % de especificidad y valores predictivos positivos y negativos de 25.6 % y 89.8 % respectivamente. No se encontraron diferencias significativas entre las mediciones semicuantitativas según sexo ni correlación lineal entre esta variable y la edad. Los valores obtenidos para el inmunoensayo presentaron diferencias significativas según el autorreporte de presencia o ausencia de síntomas compatibles con COVID-19. No se encontró correlación entre las seropositividades contra el coronavirus del síndrome respiratorio agudo grave tipo 2 y el virus del dengue. El ensayo de detección de inmunoglobulina G generó valores inferiores pero constantes en muestras de donantes voluntarios que autorreportaron no haber tenido contacto con el virus SARS-CoV-2. En contraste, las muestras de donantes expuestos al virus SARS-CoV-2 mostraron valores elevados pero variables en magnitud. Además, se observaron valores elevados y variables en muestras de voluntarios vacunados o con infección previa. Conclusiones: Nuestro ensayo de detección de inmunoglobulina M presenta escaso valor diagnóstico. Por el contrario, el ensayo de detección de inmunoglobulina G muestra un rendimiento satisfactorio y se apega al comportamiento reportado para este tipo de prueba según las características demográficas y clínicas de los usuarios; por lo tanto, este ensayo podría ser empleado como herramienta fiable y práctica en aplicaciones clínicas y como apoyo al diagnóstico. Es necesario desarrollar más estudios sobre reacciones cruzadas entre los anticuerpos contra el coronavirus del síndrome respiratorio agudo grave tipo 2 con aquellos de otras entidades de interés clínico, sobre todo las presentes en países tropicales como el nuestro.

Abstract Aim: To establish a semiquantitative immunoassay for antibody detection against the RBD of the severe acute respiratory syndrome coronavirus 2 spike protein and to evaluate its performance to be used as a diagnostic supporting tool. Methods: A recombinant severe acute respiratory syndrome coronavirus 2 spike protein was produced. This protein was used as antigenic substrate in two semiquantitative enzyme-linked immunoassays for the detection of human immunoglobulins M and immunoglobulins G. A set of serum samples (N=129) from patients with prior viral infection confirmed by reverse transcription polymerase chain reaction, processed between August 2020 and November 2021, were used as positive samples. A panel of pre-pandemic samples (N=196), obtained prior to December 2019, were used as negative samples to evaluate the assay performance. Multiple samples from 99 volunteers were used to examine test response to seroconversion. The interference between seropositivity against severe acute respiratory syndrome coronavirus 2 and dengue virus was also evaluated. Results: The immunoglobulin G detection assay showed 81.4% sensitivity, 86.2% specificity, and positive and negative predictive values of 79.5% and 87.6% respectively. The immunoglobulin M detection assay yielded 72.1% sensitivity, 54.1% specificity, and positive and negative predictive values of 25.6% and 89.8% respectively. No significant differences were found between the measurements according to sex or linear correlation between this variable and age. The values presented significant differences according to the condition of self-reported presence or absence of COVID-19 like symptoms. No correlation was found between seropositivity for severe acute respiratory syndrome coronavirus 2 and dengue virus. The immunoglobulin G detection assay generated lower but constant values on samples from voluntary donors who reported not having any contact with the virus compared to samples from donors exposed to it, and high but variable values in magnitude on samples from vaccinated volunteers or those with previous severe acute respiratory syndrome coronavirus 2 infection compared to samples from donors without exposure to the viral antigen. Conclusions: Our established immunoglobulin M detection assay presents poor diagnostic value. On the other hand, the immunoglobulin G detection assay shows satisfactory performance, and coheres to the behavior reported for this type of test according to the demographic and clinic characteristics of the volunteer, so it could be used as a reliable and practical tool in clinical applications and as diagnostic complement. It is necessary to develop more studies on cross-reactions of antibodies against severe acute respiratory syndrome coronavirus 2 with other entities of clinical interest and present in our tropical area.

No Effects of Photobiomodulation on Prefrontal Cortex and Hippocampal Cytochrome C Oxidase Activity and Expression of c-Fos Protein of Young Male and Female Rats.

The role of light in our biological processes and systems is extensively known. In addition, the use of light devices has been introduced in the field of healthcare as an opportunity to administer power light at specific wavelengths to improve our body functions and counteract light deficiency. One of these techniques is photobiomodulation (PBM), which uses red to infrared light in a non-invasive way to stimulate, heal, regenerate, and protect tissue. The main proposed mechanism of action is the stimulation of the cytochrome c oxidase (CCO), the terminal enzyme in the mitochondrial electron transport chain. PBM has achieved positive effects on brain activity and behavioral function of several adult animal models of health and disease, the potential use of this technique in developing stages is not surprising. This research aims to examine the effects of PBM on the prefrontal cortex and hippocampus of 23 day-old healthy male (n = 31) and female (n = 30) Wistar rats. Three groups of each sex were used: a PBM group which received 5 days of PBM, a device group submitted to the same conditions but without light radiation, and a control basal group. CCO histochemistry and c-Fos immunostaining were used to analyze brain metabolic activity and immediate early genes activation, respectively. Results displayed no metabolic differences between the three groups in both sexes. The same results were found in the analysis of c-Fos positive cells, reporting no differences between groups. This research, in contrast to the PBM consequences reported in healthy adult subjects, showed a lack of PBM effects in the brain markers we examined in young healthy rat brains. At this stage, brain function, specifically brain mitochondrial function, is not disturbed so it could be that the action of PBM in the mitochondria may not be detectable using the analysis of CCO activity and c-Fos protein expression. Further studies are needed to examine in depth the effects of PBM in brain development, cognitive functions and postnatal disorders, along with the exploration of the optimal light parameters.

MYC dosage compensation is mediated by miRNA-transcription factor interactions in aneuploid cancer.

We hypothesize that dosage compensation of critical genes arises from systems-level properties for cancer cells to withstand the negative effects of aneuploidy. We identified several candidate genes in cancer multiomics data and developed a biocomputational platform to construct a mathematical model of their interaction network with micro-RNAs and transcription factors, where the property of dosage compensation emerged for MYC and was dependent on the kinetic parameters of its feedback interactions with three micro-RNAs. These circuits were experimentally validated using a genetic tug-of-war technique to overexpress an exogenous MYC, leading to overexpression of the three microRNAs involved and downregulation of endogenous MYC. In addition, MYC overexpression or inhibition of its compensating miRNAs led to dosage-dependent cytotoxicity in MYC-amplified colon cancer cells. Finally, we identified negative correlation of MYC dosage compensation with patient survival in TCGA breast cancer patients, highlighting the potential of this mechanism to prevent aneuploid cancer progression.

Perturbation-Based Modeling Unveils the Autophagic Modulation of Chemosensitivity and Immunogenicity in Breast Cancer Cells.

In the absence of new therapeutic strategies, chemotherapeutic drugs are the most widely used strategy against metastatic breast cancer, in spite of eliciting multiple adverse effects and having low responses with an average 5-year patient survival rate. Among the new therapeutic targets that are currently in clinical trials, here, we addressed the association between the regulation of the metabolic process of autophagy and the exposure of damage-associated molecular patterns associated (DAMPs) to immunogenic cell death (ICD), which has not been previously studied. After validating an mCHR-GFP tandem LC3 sensor capacity to report dynamic changes of the autophagic metabolic flux in response to external stimuli and demonstrating that both basal autophagy levels and response to diverse autophagy regulators fluctuate among different cell lines, we explored the interaction between autophagy modulators and chemotherapeutic agents in regards of cytotoxicity and ICD using three different breast cancer cell lines. Since these interactions are very complex and variable throughout different cell lines, we designed a perturbation-based model in which we propose specific modes of action of chemotherapeutic agents on the autophagic flux and the corresponding strategies of modulation to enhance the response to chemotherapy. Our results point towards a promising therapeutic potential of the metabolic regulation of autophagy to overcome chemotherapy resistance by eliciting ICD.

Relationship between Prenatal or Postnatal Exposure to Pesticides and Obesity: A Systematic Review.

In recent years, the worldwide prevalence of overweight and obesity among adults and children has dramatically increased. The conventional model regarding the onset of obesity is based on an imbalance between energy intake and expenditure. However, other possible environmental factors involved, such as the exposure to chemicals like pesticides, cannot be discarded. These compounds could act as endocrine-disrupting chemicals (EDC) that may interfere with hormone activity related to several mechanisms involved in body weight control. The main objective of this study was to systematically review the data provided in the scientific literature for a possible association between prenatal and postnatal exposure to pesticides and obesity in offspring. A total of 25 human and 9 animal studies were analyzed. The prenatal, perinatal, and postnatal exposure to organophosphate, organochlorine, pyrethroid, neonicotinoid, and carbamate, as well as a combined pesticide exposure was reviewed. This systematic review reveals that the effects of pesticide exposure on body weight are mostly inconclusive, finding conflicting results in both humans and experimental animals. The outcomes reviewed are dependent on many factors, including dosage and route of administration, species, sex, and treatment duration. More research is needed to effectively evaluate the impact of the combined effects of different pesticides on human health.

Relationship between Autism Spectrum Disorder and Pesticides: A Systematic Review of Human and Preclinical Models.

Autism spectrum disorder (ASD) is a complex set of neurodevelopmental pathologies characterized by impoverished social and communicative abilities and stereotyped behaviors. Although its genetic basis is unquestionable, the involvement of environmental factors such as exposure to pesticides has also been proposed. Despite the systematic analyses of this relationship in humans, there are no specific reviews including both human and preclinical models. The present systematic review summarizes, analyzes, and discusses recent advances in preclinical and epidemiological studies. We included 45 human and 16 preclinical studies. These studies focused on Organophosphates (OP), Organochlorine (OC), Pyrethroid (PT), Neonicotinoid (NN), Carbamate (CM), and mixed exposures. Preclinical studies, where the OP Chlorpyrifos (CPF) compound is the one most studied, pointed to an association between gestational exposure and increased ASD-like behaviors, although the data are inconclusive with regard to other ages or pesticides. Studies in humans focused on prenatal exposure to OP and OC agents, and report cognitive and behavioral alterations related to ASD symptomatology. The results of both suggest that gestational exposure to certain OP agents could be linked to the clinical signs of ASD. Future experimental studies should focus on extending the analysis of ASD-like behaviors in preclinical models and include exposure patterns similar to those observed in human studies.

Differential effects of photobiomodulation interval schedules on brain cytochrome c-oxidase and proto-oncogene expression.

Significance: Transcranial photobiomodulation (PBM) is a noninvasive neuromodulation technique capable of producing changes in the mitochondrial cytochrome c-oxidase (CCO) activity of neurons. Although the application of PBM in clinical practice and as a neurophysiological tool is increasing, less is known about how different treatment time intervals may result in different outcomes. Aim: We evaluated the effects of different PBM treatment intervals on brain metabolic activity through the CCO and proto-oncogene expression (c-Fos). Approach: We studied PBM effects on brain CCO and c-Fos expression in three groups of animals: Control (CN, n = 8 ), long interval PBM treatment (LI, n = 5 ), and short interval PBM treatment (SI, n = 5 ). Results: Increased CCO activity in the LI group, compared to the SI and CN groups, was found in the prefrontal cortices, dorsal and ventral striatum, and hippocampus. Regarding c-Fos expression, we found a significant increase in the SI group compared to LI and CN, whereas LI showed increased c-Fos expression compared to CN in the cingulate and infralimbic cortices. Conclusions: We show the effectiveness of different PBM interval schedules in increasing brain metabolic activity or proto-oncogene expression.

The Relationship between Choline Bioavailability from Diet, Intestinal Microbiota Composition, and Its Modulation of Human Diseases.

Choline is a water-soluble nutrient essential for human life. Gut microbial metabolism of choline results in the production of trimethylamine (TMA), which, upon absorption by the host is converted into trimethylamine-N-oxide (TMAO) in the liver. A high accumulation of both components is related to cardiovascular disease, inflammatory bowel disease, non-alcoholic fatty liver disease, and chronic kidney disease. However, the relationship between the microbiota production of these components and its impact on these diseases still remains unknown. In this review, we will address which microbes contribute to TMA production in the human gut, the extent to which host factors (e.g., the genotype) and diet affect TMA production, and the colonization of these microbes and the reversal of dysbiosis as a therapy for these diseases.

How Does Maternal Separation Affect the Cerebellum? Assessment of the Oxidative Metabolic Activity and Expression of the c-Fos Protein in Male and Female Rats.

Early life stress increases the risk of abnormal brain development, and it is associated with psychological disorders. Maternal separation is an established animal model of early life stress that produces changes in the development of the central nervous system. The objective of this study was to evaluate the effect of maternal separation on the rat cerebellum, both behaviourally and physiologically. We used 32 rats, males (n = 8) and females (n = 7), subjected to maternal separation for 21 days and a control group (9 males and 8 females). Spatial reference memory was assessed using the Morris water maze, and brain metabolic activity and the expression of an immediate early gene were determined, respectively, using the histochemical technique of cytochrome c oxidase and the immunocytochemistry of c-Fos. Results showed that both groups successfully performed the spatial memory task. Although there were no behavioural differences, the experimental group showed lower metabolic activity in the medial nucleus of the cerebellum, as well as fewer c-Fos-positive cells in the three deep nuclei of the cerebellum. These decreases could contribute to the emotional or behavioural impairments reported in maternal separation subjects.

High frequency repetitive transcranial magnetic stimulation improves neuronal activity without affecting astrocytes and microglia density.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique capable of producing changes in the electrical potential of neurons. Currently, the application of rTMS in clinical practice and as a neurophysiological tool is increasing. However, the exact cellular mechanisms underlying rTMS-based therapies are not completely clear. Additionally, glial cells have been studied less. Our aim was to investigate the effect of three days of high-frequency rTMS on neuronal metabolism and neuronal activation, in addition to its effect on glial cells. For this purpose, we performed histochemistry and immunohistochemistry procedures: the histochemistry of cytochrome oxidase (COx) to assess neuronal metabolic activity, and the immunohistochemistry of c-Fos (marker of neuronal activity), GFAP (marker of astrocytic reactivity), and Iba1 (selective marker of reactive microglia). Our results showed enhanced metabolic activity after rTMS in the retrosplenial and parietal cortex and CA1 and CA3 subfields of the hippocampus. Moreover, higher c-Fos activity was found in the agranular retrosplenial cortex. Finally, we did not find changes between groups in the induction of astrocyte and microglia reactivity in any of the immunostained regions. In conclusion, we can assume that three days of high-frequency rTMS applied in healthy rats does not alter astroglia reactivity or inflammatory responses, such as microglia proliferation. Because we have shown an upregulation of neuronal metabolic activity in many limbic brain structures, in addition to higher c-Fos levels in the nearest cortical area to the rTMS, our work provides novel insight into the effectiveness and safety of rTMS as a brain modulation therapy.

Early life stress by repeated maternal separation induces long-term neuroinflammatory response in glial cells of male rats.

Childhood maltreatment and neglect lead to a wide range of mental disorders highlighted by hormone and immune alterations in neglected children. This social-health challenge has led to the creation of early stress models such as maternal separation (MS) in rodents. We performed a MS model (4 h per day, 21 days; n = 16 MS and n = 16 control), and then measured three parameters in adult male rat brains, in order to look for long-term effects of early life stress. We used immunocytochemistry to mark glial fibrillary acidic protein (GFAP)-positive cells, which indicates changes in astroglia, and ionized calcium binding adaptor molecule 1 (Iba-1)-positive cells, which inform about reactive microglia. In order to study mRNA levels of some immune mediators, interleukin determination (interleukin-6, IL-6; tumor necrosis factor, TNFα) mRNAs were evaluated by real-time polymerase chain reaction (rt-PCR) in discrete brain regions. Measurements of numbers of GFAP-positive cells, and expression of Iba-1, IL-6 and TNFα mRNAs were performed in prefrontal cortex (PFC): cingulate cortex (CG), prelimbic cortex (PL) and infralimbic cortex (IL), striatal areas (dorsal striatum, STD; and nucleus accumbens, ACC), and dorsal hippocampus (HC: CA1, CA3 and dentate gyrus (DG)). We found that MS produces a dramatic and sustained decrease in the astroglial population in all the areas measured (from -25% in CA1 to -85.7% in ACC), whereas increased numbers of microglia were found, in more restricted regions: STD (72.6%), ACC (31%) and CA3 (33.3%) areas. Regarding mRNA measurements, we found increased IL-6 mRNA expression in HC (104.2%), and after MS.

Adult social isolation leads to anxiety and spatial memory impairment: Brain activity pattern of COx and c-Fos.

Social isolation during adulthood is a frequent problem that leads to a large variety of adverse emotional and cognitive effects. However, most of the social isolation rodent procedures begin the separation early post-weaning. This work explores locomotor activity, anxiety-like behaviour, and spatial working memory after twelve weeks of adult social isolation. In order to study the functional contribution of selected brain areas following a working memory task, we assessed neuronal metabolic activity through quantitative cytochrome oxidase histochemistry and c-Fos immunohistochemistry. Behaviourally, we found that isolated animals (IS) showed anxiety-like behaviour and worse working memory than controls, whereas motor functions were preserved. Moreover, IS rats showed lower levels of learning-related c-Fos immunoreactivity, compared to controls, in the medial prefrontal cortex (mPFC), ventral tegmental area (VTA), and nucleus accumbens shell. In addition, the IS group showed lower neuronal metabolic activity in the mPFC, VTA, and CA1 subfield of the hippocampus. These results indicate that twelve weeks of social isolation in adult rats leads to different behavioural and brain alterations, and they highlight the importance of social support, not only in development, but also in adulthood.

Dengue Virus Infection of Primary Human Smooth Muscle Cells.

Dengue virus (DENV) infection of humans is presently the most important arthropod-borne viral global threat, for which no suitable or reliable animal model exists. Reports addressing the effect of DENV on vascular components other than endothelial cells are lacking. Dengue virus infection of vascular smooth muscle cells, which play a physiological compensatory response to hypotension in arteries and arterioles, has not been characterized, thus precluding our understanding of the role of these vascular components in dengue pathogenesis. Therefore, we studied the permissiveness of primary human umbilical artery smooth muscle cells (HUASMC) to DENV 1-4 infection and compared with the infection in the previously reported primary human umbilical vein endothelial cells (HUVEC) and the classically used, non-transformed, and highly permissive Lilly Laboratories Cell-Monkey Kidney 2 cells. Our results show that HUASMC are susceptible and productive to infection with the four DENV serotypes, although to a lesser extent when compared with the other cell lines. This is the first report of DENV permissiveness in human smooth muscle cells, which might represent an unexplored pathophysiological contributor to the vascular collapse observed in severe human dengue infection.

Why are maternally separated females inflexible? Brain activity pattern of COx and c-Fos.

Subjects' early life events will affect them later in life. When these events are stressful, such as child abuse in humans or repeated maternal separation in rodents, subjects can show some behavioral and brain alterations. This study used young adult female Wistar rats that were maternally raised (AFR), maternally separated from post-natal day (PND) 1 to PND10 (MS10), or maternally separated from PND1 to PND21 (MS21), in order to assess the effects of maternal separation (MS) on spatial learning and memory, as well as cognitive flexibility, using the Morris Water Maze (MWM). We performed quantitative cytochrome oxidase (COx) histochemistry on selected brain areas in order to identify whether maternal separation affects brain energy metabolism. We also performed c-Fos immunohistochemistry on the medial prefrontal cortex (mPFC), thalamus, and hippocampus to explore whether this immediate early gene activity was altered in stressed subjects. We obtained a similar spatial learning pattern in maternally raised and maternally separated subjects on the reference memory task, but only the controls were flexible enough to solve the reversal learning successfully. Separated groups showed less c-Fos activity in the mPFC and less complex neural networks on COx.

Assessing the brain through the eye: New ways to explore hepatic encephalopathy.

BACKGROUND & AIMS: Minimal hepatic encephalopathy (mHE) has been shown to affect daily functioning, quality of life, driving and overall mortality. However, little is known about treating or diagnosing early impairments in mHE. We studied one of its precipitating factors, portal hypertension which is driving the inflammatory process behind mHE. The purpose was to describe an indirect diagnostic method able to detect the pathology at early stages based on the study of the vascularization and mast cells conjunctival hyperplasia as secondary inflammatory response associated to portal hypertension. Finally, we correlated the presence of histological changes in the eye in mHE with deficits in behavioral task acquisition. METHODS: Rats were trained on a stimulus-response task and a spatial working memory task using the Morris water maze. Two groups of animals were used: a SHAM (sham-operated) group (n=10) and a portal hypertension (HT) group (n=10). The triple portal vein ligation method was used to create an animal model of mHE. Latencies to reach the platform, number of glial fibrillary acidic protein-immunoreactive astrocytes (GFAP-IR), mast cell expression and presence/absence of blood and lymphatic vessels were examined. RESULTS: There were differences in stimulus-response behavioral performance, with a deficit in the acquisition in the HT group. However, no differences between groups were found on the spatial working memory task. At the same time, differences between groups were found in the GFAP-IR density, which was lower in the HT group, and in the number of mast cells and the presence of vessels, which were higher in the HT group. CONCLUSIONS: In this study, we provide the first preliminary insight into the validity of exploring the eye as a possible tool to assess the diagnosis of mHE conditions.

Low-light-level therapy as a treatment for minimal hepatic encephalopathy: behavioural and brain assessment.

Minimal hepatic encephalopathy (MHE) has been shown to affect daily functioning, quality of life, driving and overall mortality. However, little is known about treating or diagnosing early impairments involved in MHE. We studied one of its precipitating factors, portal hypertension. The purpose was to evaluate an enhancement in neuronal metabolism through low-light-level therapy (LLLT) and whether this therapy has effects on behavioural task acquisition. Rats were trained to perform a stimulus-response task using the Morris water maze. Three groups of animals were used: a SHAM (sham-operated) group (n = 7), a portal hypertension (PH) group (n = 7) and a PH + LLLT group (n = 7). The triple portal vein ligation method was used to create an animal model of the early developmental phase of HE, and then the animals were exposed to 670 + 10 nm LED light at a dose of 9 J/cm2 once a day for 7 days. The metabolic activity of the brains was studied with cytochrome c oxidase histochemistry. There were differences in behavioural performance, with an improvement in the PH + LLLT group. Energetic brain metabolism revealed significant differences between the groups in all the brain structures analysed, except the anterodorsal thalamus. At the same time, in different brain networks, the PH group showed a more complicated relationship among the structures, while the SHAM and PH + LLLT groups had similar patterns. In this study, we provide the first preliminary insights into the validity of LLLT as a possible intervention to improve memory under minimal hepatic encephalopathy conditions.

Finding the place without the whole: Timeline involvement of brain regions.

Mastering the Morris water maze (MWM) requires the animal to consolidate, retain and retrieve spatial localizations of relevant visual cues. However, it is necessary to investigate whether a reorganization of the neural networks takes place when part of the spatial information is removed. We conducted four experiments using the MWM. A classical reference memory procedure was performed over five training days, RM5 (n=7), and eight days, RM8 (n=7), with the whole room and all the spatial cues presented. Another group of animals were trained in the same protocol, but they received an additional day of training with only partial cues, PC (n=8). Finally, a third group of animals performed the classical task, followed by an overtraining with partial cues for four more days, OPC (n=8). After completing these tasks, cytochrome c-oxidase activity (CO) in several brain limbic system structures was compared between groups. In addition, c-Fos positive cells were measured in the RM5, RM8, PC and OPC groups. No significant differences were found among the four groups in escape latencies or time spent in the target quadrant. CO revealed involvement of the prefrontal and parietal cortices, dorsal and ventral striatum, CA1 and CA3 subfields of the dorsal hippocampus, basolateral and lateral amygdala, and mammillary nuclei in the PC group, compared to the RM group. In the OPC group, involvement of the ventral striatum and anteroventral thalamus and the absence of amygdala involvement were revealed, compared to the PC group. C-Fos results highlighted the role of the prefrontal cortex, dorsal striatum, anterodorsal thalamus and CA3 in the PC group, compared to the OPC, RM5 and RM8 groups. The animals were able to find the escape platform even when only a portion of the space where the cues were placed was available. Although the groups did not differ behaviorally, energetic brain metabolism and immediate early gene expression revealed the engagement of different neural structures in the groups that received more training without the entire surrounding space.

c-Fos expression correlates with performance on novel object and novel place recognition tests.

In rodents, many studies have been carried out using novelty-preference paradigms. The results show that the perirhinal cortex and the hippocampus are involved in the recognition of a novel object, "what", and its new position, "where", respectively. We employed these two variants of a novelty-preference paradigm to assess whether the expression of the immediate-early gene c-fos in the dorsal hippocampus and perirhinal cortex correlates with the performance discrimination ratio (d2), on the respective versions of the novelty preference tests. A control group (CO) was added to explore c-fos activation not specific to recognition. The results showed different patterns of c-Fos protein expression in the hippocampus and perirhinal cortex. The Where Group presented more c-Fos positive nuclei than the What and CO groups in the CA1 and CA3 regions, whereas in the perirhinal cortex, the What Group showed more c-Fos positive nuclei than the Where and CO groups. The correlation results indicate that levels of c-Fos in the CA1 area and perirhinal cortex correlate with effective exploration, d2, on the respective versions of the novelty preference tests, novel place and novel object recognition. These data suggest that the hippocampal CA1 and perirhinal cortex are specifically related to the level of recognition of place and objects, respectively.

Main target of minimal hepatic encephalopathy: Morphophysiological, inflammatory and metabolic view.

Although often not considered clinically relevant and, therefore, not diagnosed or treated, minimal hepatic encephalopathy (MHE) has been shown to affect daily functioning, quality of life, driving and overall mortality. To discover early impairments involved in MHE, we studied one of its precipitating factors, portal hypertension. Rats were trained on a stimulus-response task using the Morris water maze. Two groups of animals were used: a SHAM (sham-operated) group (n= 13) and a portal hypertension (PH) group (n= 13). The triple portal vein ligation method was used to create an animal model of an early developmental phase of HE. Brain metabolic activity was studied with cytochrome c-oxidase histochemistry (C.O.). Neuronal nuclear volume was assessed by nucleator probe; the number of glial fibrillary acidic protein-immunoreactive astrocytes (GFAP-IR) and proinflammatory mediators was measured. The results revealed that the PH group was not able to reach the behavioural criterion, in contrast to the SHAM group. The metabolic brain consumption revealed decreased C.O. activity in the ventral striatum. The PH group showed lower density of GFAP-IR and an increase in the tumour necrotic factor-α (TNF-α). The PH group showed decreased neuronal nuclear volume in the dorsal striatum. On the contrary, increased neuronal nuclear volume was found in the ventral striatum. For the first time, a relationship has been established between inflammation, astrocytic and neural damage, and brain metabolic impairment in a model of MHE. Disruption of the striatum and related structures was highlighted as the main target in early stages of HE. Finally, a simple task was presented to assess the subtle impairments found in the clinic, which could provide fresh insights into the development of new tools for the assessment of MHE.