Measuring the perception and metacognition of time.

The ability of humans to identify and reproduce short time intervals (in the region of a second) may be affected by many factors ranging from the gender and personality of the individual observer, through the attentional state, to the precise spatiotemporal structure of the stimulus. The relative roles of these very different factors are a challenge to describe and define; several methodological approaches have been used to achieve this to varying degrees of success. Here we describe and model the results of a paradigm affording not only a first-order measurement of the perceived duration of an interval but also a second-order metacognitive judgement of perceived time. This approach, we argue, expands the form of the data generally collected in duration-judgements and allows more detailed comparison of psychophysical behavior to the underlying theory. We also describe a hierarchical Bayesian measurement model that performs a quantitative analysis of the trial-by-trial data calculating the variability of the temporal estimates and the metacognitive judgments allowing direct comparison between an actual and an ideal observer. We fit the model to data collected for judgements of 750 ms (bisecting 1500 ms) and 1500 ms (bisecting 3000 ms) intervals across three stimulus modalities (visual, audio, and audiovisual). This enhanced form of data on a given interval judgement and the ability to track its progression on a trial-by-trial basis offers a way of looking at the different roles that subject-based, task-based and stimulus-based factors have on the perception of time.

The neurobiological effects of senescence on dopaminergic system: A comprehensive review.

Over time, the body undergoes a natural, multifactorial, and ongoing process named senescence, which induces changes at the molecular, cellular, and micro-anatomical levels in many body systems. The brain, being a highly complex organ, is particularly affected by this process, potentially impairing its numerous functions. The brain relies on chemical messengers known as neurotransmitters to function properly, with dopamine being one of the most crucial. This catecholamine is responsible for a broad range of critical roles in the central nervous system, including movement, learning, cognition, motivation, emotion, reward, hormonal release, memory consolidation, visual performance, sexual drive, modulation of circadian rhythms, and brain development. In the present review, we thoroughly examine the impact of senescence on the dopaminergic system, with a primary focus on the classic delimitations of the dopaminergic nuclei from A8 to A17. We provide in-depth information about their anatomy and function, particularly addressing how senescence affects each of these nuclei.

Adult human neural cells in culture following traumatic brain injury

Objective: The present study aims to evaluate the viability of adult human neural cells in culture obtained from traumatized brain tissues collected in emergency surgery procedures. Methods: Exploratory, descriptive, quantitative and cross-sectional study evaluating samples obtained from patients who underwent traumatic brain injury with extrusion of brain tissue submitted to cell culture in a standardized medium, being preserved during 168h. After observation under phase contrast microscopy and immunohistochemical processing for neuronal (MAP-2) and glial (GFAP) markers, morphometric parameters of neural cells (cell body area, dendritic field length and fractal dimension) were evaluated using ImageJ software, with data obtained after 24, 72 and 168h being compared using non-parametric Kruskal Wallis test, followed by Dunn's post hoc test. Results: The explant of the nervous tissue revealed a consolidated pattern of cell migration into the culture medium. Cell proliferation, upon reaching confluence, presented an aspect of cellular distribution juxtaposed along the culture medium at all time points analyzed. Both neurons and glial cells remained viable after 168h in culture, with their morphologies not varying significantly throughout the time points evaluated. Immunohistochemistry for MAP-2 showed a relatively well-preserved cytoskeletal organization. GFAP immunoreactivity revealed activated astrocytes especially at the later time point. Conclusions: Our results point out the viability of cell culture from traumatized human nervous tissue, opening up perspectives for the use of substances of natural origin that may contribute neuroprotectively to neuronal maintenance in culture, allowing future translational approach.

Fatores de risco para a Síndrome de burnout em enfermeiros de um hospital público de Mossoró/RN, Brasil / Risk factors for burnout syndrome in nurses at a public hospital in Mossoró/RN, Brazil

Objetivo: Avaliar os fatores de risco para o aparecimento da Síndrome de burnout em enfermeiros trabalhadores do Hospital Regional Tarcísio de Vasconcelos Maia em Mossoró/RN. Métodos: Estudo exploratório, descritivo, quantitativo e transversal com 119 enfermeiros de março a setembro de 2022. Os dados foram coletados a partir da aplicação de um formulário com informações sócio-organizacionais e do Copenhagen Burnout Inventory, contendo 19 itens que refletem o burnout profissional em uma escala categorizada como burnout baixo, intermediário e alto. Resultados: A maioria dos entrevistados era do sexo feminino (81%), com média de 36,4 anos de idade, casada (70%), com especialização na área (74%) e dois empregos (59%). Identificou-se maior prevalência de níveis elevados de burnout pessoal (44%) e níveis intermediários de burnoutrelacionado ao trabalho (52%) e relacionado ao cliente (50%). Houve forte correlação positiva entre número de vínculos empregatícios para as dimensões burnout pessoal (r = 0,74; p = 0,03) e relacionado ao trabalho (r = 0,81; p = 0,02), forte correlação positiva entre carga horária de trabalho e burnout pessoal (r = 0,68; p = 0,04) e moderada correlação positiva entre carga horária de trabalho e burnout relacionado ao trabalho (r = 0,53; p = 0,04). Conclusões: A exposição a jornadas de trabalho prolongadas resultou em aumento dos níveis de exaustão física e psíquica nos enfermeiros, interferindo negativamente nos aspectos profissionais e pessoais. Estudos futuros focando em estratégias para garantir uma melhor condição de trabalho ao enfermeiro são necessários, visando proporcionar uma melhor saúde ocupacional aos trabalhadores

Objective: To evaluate the risk factors for the onset of burnout syndrome in nursing workers at the Hospital Regional Tarcísio de Vasconcelos Maia in Mossoró/RN. Methods: Exploratory, descriptive, quantitative and cross-sectional study with 119 nurses from March to September 2022. Data were collected from the application of a form with socio-organizational information and the Copenhagen Burnout Inventory, containing 19 items that reflect the professional burnout on a scale categorized as low, intermediate and high burnout. Results: Most respondents were female (81%), with an average age of 36.4 years, married (70%), with specialization in the area (74%) and two jobs (59%). A higher prevalence of high levels of personal burnout (44%) and intermediate levels of work-related (52%) and client-related burnout (50%) were identified. There was a strong positive correlation between the number of employment relationships for the personal burnout (r = 0.74; p = 0.03) and work-related (r = 0.81; p = 0.02) dimensions, a strong positive correlation between load hours of work and personal burnout (r = 0.68; p = 0.04) and a moderate positive correlation between workload and work-related burnout (r = 0.53; p = 0.04). Conclusions: Exposure to long working hours resulted in increased levels of physical and mental exhaustion in nurses, negatively interfering with professional and personal aspects. Future studies focusing on strategies to ensure a better working condition for nurses are needed, aiming to provide better occupational health for workers. Keywords: Burnout syndrome; Occupational stress; Nursing

Avaliação da comunicação social de crianças até 12 anos com Transtorno do Espectro Autista em Centro de Atendimento Psicossocial / Evaluation of the social communication of children up to 12 years old with Autism Spectrum Disorder in a Psychosocial Care Center

Objetivo: Caracterizar a comunicação social em crianças até 12 anos diagnosticadas com Transtorno do Espectro Autista (TEA) atendidos no Centro de Atenção Psicossocial Infantil (CAPSi) da cidade de Mossoró/RN. Métodos: Pesquisa exploratória, descritiva, quantitativa, transversal, realizada no CAPSi de Mossoró/RN. A coleta de dados baseou-se na aplicação de questionários aos pais/responsáveis, para caracterizar suas condições socioeconômicas e sua percepção sobre seus filhos. Foi utilizado o instrumento Avaliação do Desenvolvimento da Linguagem (ADL) para crianças, desenvolvido para avaliar a aquisição e desenvolvimento de conteúdo (semântica) e estrutura (morfologia e sintaxe) da linguagem. Os questionários foram codificados e os dados foram tabulados para posterior análise estatística. Resultados: Foram estudadas 33 crianças e 73 pais/responsáveis. A maioria dos pais/responsáveis era do sexo feminino (95,9%), predominantemente na faixa etária de 30-39 anos (média de 37,6 anos), com cônjuge (60%), com ensino médio completo (45%) e renda mensal em torno de um salário-mínimo (76,7%), possuindo atitudes positivas em relação aos filhos e notando dificuldades na comunicação destes. Na aplicação do questionário com as crianças, 63,7% apresentaram resultados na faixa de normalidade, enquanto 3% apresentaram alteração leve e 33,3% alteração grave de linguagem. Conclusão: Crianças com TEA frequentadoras do CAPSi apresentam alterações de linguagem no subnível pragmático e mais da metade dos participantes não apresenta alterações morfossintáticas e semânticas

Objective: To characterize social communication in children up to 12 years old diagnosed with Autistic Spectrum Disorder (ASD) treated at the Child Psychosocial Care Center (CAPSi) in Mossoró/RN. Methods: Exploratory, descriptive, quantitative, cross-sectional study conducted at CAPSi in Mossoró/RN. The data collection was based on the application of questionnaires to parents/guardians to characterize their socioeconomic conditions and their perception of their children. The Language Development Assessment (LDA) instrument for children was used, developed to assess the acquisition and development of language content (semantics) and structure (morphology and syntax). The questionnaires were coded, and the data were tabulated for further statistical analysis. Results: 33 children and 73 parents/guardians were studied. Most parents/guardians were female (95.9%), aged 30-39 years (mean age 37.6 years predominantly), with a partner (60%), with high school education (45%), and monthly income around one minimum wage (76.7%), having positive attitudes toward their children and noticing difficulties in their communication. In applying the questionnaire to the children, 63.7% presented results within the normal range, while 3% presented mild and 33.3% severe language alterations. Conclusion: Children with ASD attending CAPSi have language disorders in the pragmatic sublevel, and more than half of the participants did not have morphosyntactic and semantic changes

Cellular and Molecular Pathophysiology of Traumatic Brain Injury: What Have We Learned So Far?

Traumatic brain injury (TBI) is one of the leading causes of long-lasting morbidity and mortality worldwide, being a devastating condition related to the impairment of the nervous system after an external traumatic event resulting in transitory or permanent functional disability, with a significant burden to the healthcare system. Harmful events underlying TBI can be classified into two sequential stages, primary and secondary, which are both associated with breakdown of the tissue homeostasis due to impairment of the blood-brain barrier, osmotic imbalance, inflammatory processes, oxidative stress, excitotoxicity, and apoptotic cell death, ultimately resulting in a loss of tissue functionality. The present study provides an updated review concerning the roles of brain edema, inflammation, excitotoxicity, and oxidative stress on brain changes resulting from a TBI. The proper characterization of the phenomena resulting from TBI can contribute to the improvement of care, rehabilitation and quality of life of the affected people.

Statistical analysis of blast-induced vibration near an open pit mine.

Blast-induced vibration may be harmful to facilities in the vicinity of operating mines, mainly causing structural damage and human discomfort. This study presents an application of multivariate statistics to predict vibration levels regarding their potential to cause structural damage and human discomfort. An extensive seismic monitoring campaign was executed in a large open-pit iron ore mine, near a small village, to gather a dataset for a predictive multivariate analysis. Ten blasting events have produced a dataset of 158 valid measurements. Three classes of vibration peak velocity were adopted from legal standards, which later supported a cluster analysis. Then, it was possible to compare how much these two classification modalities respond to discriminant analysis. The next step was to carry out a principal component analysis (PCA) from the original database, and, comparatively, to plot both the scores concerning the classes derived from the vibration standard and those from the groups obtained from cluster analysis. PCA has considerably explained the data variability, while the three classes from cluster analysis resulted very similar to the corresponding ones from the vibration standards. The results have demonstrated that multivariate statistics may be applied to manage blasting-induced vibration and its deleterious effects with few adjustments and automation.

Aerobic Physical Training Attenuates Oxidative Stress in the Spinal Cord of Adult Rats Induced by Binge-like Ethanol Intake.

Binge drinking is the most frequent consumption pattern among young adults and remarkably changes the central nervous system; thus, research on strategies to protect it is relevant. This study aimed to investigate the detrimental effects of binge-like EtOH intake on the spinal cord of male rats and the potential neuroprotective effects provided by moderate-intensity aerobic physical training. Male Wistar rats were distributed into the 'control group', 'training group', 'EtOH group', and 'training + EtOH'. The physical training protocol consisted of daily 30-min exercise on a treadmill for 5 consecutive days followed by 2 days off during 4 weeks. After the fifth day of each week, distilled water ('control group' and 'training group') or 3 g/kg of EtOH diluted at 20% w/v ('EtOH group' and 'training + EtOH group') was administered for 3 consecutive days through intragastric gavage to simulate compulsive consumption. Spinal cord samples were collected for oxidative biochemistry and morphometric analyses. The binge-like EtOH intake induced oxidative and tissue damage by decreasing reduced glutathione (GSH) levels, increasing lipid peroxidation (LPO), and reducing motor neurons (MN) density in the cervical segment. Even under EtOH exposure, physical training maintained GSH levels, reduced LPO, and prevented MN reduction at the cervical segment. Physical training is a non-pharmacological strategy to neuroprotect the spinal cord against oxidative damage induced by binge-like EtOH intake.

Astrocytosis, Inflammation, Axonal Damage and Myelin Impairment in the Internal Capsule following Striatal Ischemic Injury.

Secondary degeneration is defined as a set of destructive events that damage cells and structures that were initially spared or only peripherally affected by the primary insult, constituting a key factor for functional impairment after traumatic brain injury or stroke. In the present study, we evaluated the patterns of astrocytosis, inflammatory response, axonal damage and oligodendrocytes/myelin impairment in the internal capsule following a focal injection of endothelin-1 (ET-1) into the dorsal striatum. Animals were perfused at 1, 3 and 7 post-lesion days (PLD), and tissue was processed to immunohistochemistry for neutrophils (MBS1), macrophages/microglia (ED1), astrocytes (GFAP), axonal lesion (ßAPP), oligodendrocytes (Tau) and myelin (MBP). A significant number of neutrophils was observed at 1PLD, followed by intense recruitment/activation of macrophages/microglia at 3PLD and astrocytic reaction with a peak at 7PLD. Oligodendrocyte damage was pronounced at 3PLD, remaining at 7PLD. Progressive myelin impairment was observed, with reduction of immunoreactivity at 7PLD. Axonal lesion was also identified, mainly at 7PLD. Our results indicate that acute inflammatory response elicited by the ischemic insult in the striatum can be associated with the axonal impairment and damage of both oligodendrocytes and myelin sheath identified in the internal capsule, which may be related to loss of tissue functionality observed in secondary degeneration.

Deciphering peroxisomal reactive species interactome and redox signalling networks.

Plant peroxisomes are highly dynamic organelles with regard to metabolic pathways, number and morphology and participate in different metabolic processes and cell responses to their environment. Peroxisomes from animal and plant cells house a complex system of reactive oxygen species (ROS) production associated to different metabolic pathways which are under control of an important set of enzymatic and non enzymatic antioxidative defenses. Nitric oxide (NO) and its derivate reactive nitrogen species (RNS) are also produced in these organelles. Peroxisomes can regulate ROS and NO/RNS levels to allow their role as signalling molecules. The metabolism of other reactive species such as carbonyl reactive species (CRS) and sulfur reactive species (SRS) in peroxisomes and their relationship with ROS and NO have not been explored in depth. In this review, we define a peroxisomal reactive species interactome (PRSI), including all reactive species ROS, RNS, CRS and SRS, their interaction and effect on target molecules contributing to the dynamic redox/ROS homeostasis and plasticity of peroxisomes, enabling fine-tuned regulation of signalling networks associated with peroxisome-dependent H2O2. Particular attention will be paid to update the information available on H2O2-dependent peroxisomal retrograde signalling and to discuss a specific peroxisomal footprint.

Organization of Somatosensory Cortex in the South American Rodent Paca (Cuniculus paca).

INTRODUCTION: The study of non-laboratory species has been part of a broader effort to establish the basic organization of the mammalian neocortex, as these species may provide unique insights relevant to cortical organization, function, and evolution. METHODS: In the present study, the organization of three somatosensory cortical areas of the medium-sized (5-11 kg body mass) Amazonian rodent, the paca (Cuniculus paca), was determined using a combination of electrophysiological microelectrode mapping and histochemical techniques (cytochrome oxidase and NADPH diaphorase) in tangential sections. RESULTS: Electrophysiological mapping revealed a somatotopically organized primary somatosensory cortical area (S1) located in the rostral parietal cortex with a characteristic foot-medial/head-lateral contralateral body surface representation similar to that found in other species. S1 was bordered laterally by two regions housing neurons responsive to tactile stimuli, presumably the secondary somatosensory (S2) and parietal ventral (PV) cortical areas that evinced a mirror-reversal representation (relative to S1) of the contralateral body surface. The limits of the putative primary visual (V1) and primary auditory (A1) cortical areas, as well as the complete representation of the contralateral body surface in S1, were determined indirectly by the histochemical stains. Like the barrel field described in small rodents, we identified a modular arrangement located in the face representation of S1. CONCLUSIONS: The relative location, somatotopic organization, and pattern of neuropil histochemical reactivity in the three paca somatosensory cortical areas investigated are similar to those described in other mammalian species, providing additional evidence of a common plan of organization for the somatosensory cortex in the rostral parietal cortex of mammals.

Global Proteomic Profile of Aluminum-Induced Hippocampal Impairments in Rats: Are Low Doses of Aluminum Really Safe?

Hippocampus is the brain area where aluminum (Al) accumulates in abundance and is widely associated with learning and memory. In the present study, we evaluate behavioral, tissue, and proteomic changes in the hippocampus of Wistar rats caused by exposure to doses that mimic human consumption of aluminum chloride (AlCl3) in urban areas. For this, male Wistar rats were divided into two groups: Control (distilled water) and AlCl3 (8.3 mg/kg/day), both groups were exposed orally for 60 days. After the Al exposure protocol, cognitive functions were assessed by the Water maze test, followed by a collection for analysis of the global proteomic profile of the hippocampus by mass spectrometry. Aside from proteomic analysis, we performed a histological analysis of the hippocampus, to the determination of cell body density by cresyl violet staining in Cornu Ammonis fields (CA) 1 and 3, and hilus regions. Our results indicated that exposure to low doses of aluminum chloride triggered a decreased cognitive performance in learning and memory, being associated with the deregulation of proteins expression, mainly those related to the regulation of the cytoskeleton, cellular metabolism, mitochondrial activity, redox regulation, nervous system regulation, and synaptic signaling, reduced cell body density in CA1, CA3, and hilus.

Microelectrode implants, inflammatory response and long-lasting effects on NADPH diaphorase neurons in the rat frontal cortex.

At present, one of the main therapeutic challenges comprises the development of technologies to improve the life quality of people suffering from different types of body paralysis, through the reestablishment of sensory and motor functions. In this regard, brain-machine interfaces (BMI) offer hope to effectively mitigate body paralysis through the control of paralyzed body parts by brain activity. Invasive BMI use chronic multielectrode implants to record neural activity directly from the brain tissue. While such invasive devices provide the highest amount of usable neural activity for BMI control, they also involve direct damage to the nervous tissue. In the cerebral cortex, high levels of the enzyme NADPH diaphorase (NADPH-d) characterize a particular class of interneurons that regulates neuronal excitability and blood supply. To gain insight into the biocompatibility of invasive BMI, we assessed the impact of chronic implanted tungsten multielectrode bundles on the distribution and morphology of NADPH-d-reactive neurons in the rat frontal cortex. NADPH-d neuronal labeling was correlated with glial response markers and with indices of healthy neuronal activity measured by electrophysiological recordings performed up to 3 months after multielectrode implantation. Chronic electrode arrays caused a small and quite localized structural disturbance on the implanted site, with neuronal loss and glial activation circumscribed to the site of implant. Electrodes remained viable during the entire period of implantation. Moreover, neither the distribution nor the morphology of NADPH-d neurons was altered. Overall, our findings provide additional evidence that tungsten multielectrodes can be employed as a viable element for long-lasting therapeutic BMI applications.

Platelet Lipidome Fingerprint: New Assistance to Characterize Platelet Dysfunction in Obesity.

Obesity is associated with a pro-inflammatory and pro-thrombotic state that supports atherosclerosis progression and platelet hyper-reactivity. During the last decade, the platelet lipidome has been considered a treasure trove, as it is a source of biomarkers for preventing and treating different pathologies. The goal of the present study was to determine the lipid profile of platelets from non-diabetic, severely obese patients compared with their age- and sex-matched lean controls. Lipids from washed platelets were isolated and major phospholipids, sphingolipids and neutral lipids were analyzed either by gas chromatography or by liquid chromatography coupled to mass spectrometry. Despite a significant increase in obese patient's plasma triglycerides, there were no significant differences in the levels of triglycerides in platelets among the two groups. In contrast, total platelet cholesterol was significantly decreased in the obese group. The profiling of phospholipids showed that phosphatidylcholine and phosphatidylethanolamine contents were significantly reduced in platelets from obese patients. On the other hand, no significant differences were found in the sphingomyelin and ceramide levels, although there was also a tendency for reduced levels in the obese group. The outline of the glycerophospholipid and sphingolipid molecular species (fatty-acyl profiles) was similar in the two groups. In summary, these lipidomics data indicate that platelets from obese patients have a unique lipid fingerprint that may guide further studies and provide mechanistic-driven perspectives related to the hyperactivate state of platelets in obesity.

Intrauterine and Postnatal Exposure to High Levels of Fluoride Is Associated with Motor Impairments, Oxidative Stress, and Morphological Damage in the Cerebellum of Offspring Rats.

Fluoride (F) is abundantly present on Earth and plays a beneficial role in human health. However, exposure to high doses of F can be a risk, mainly in endemic fluorosis regions. In light of this, we investigated the effects of F exposure during the intrauterine and postnatal periods of rats, in doses similar to those recommended in drinking water and the levels of F in regions with endemic fluorosis, on the offspring rats' cerebellum. Pregnant rats were divided into three groups: control (received ultrapure water only), 10 mg F/L, and 50 mg F/L for a period of 42 days (21 days gestation and 21 days lactation). At the end of the lactation period, the male pups were evaluated by behavioral tests, morphological markers, and biochemistry assays. The results pointed out that 50 mg F/L exposure during the intrauterine and lactational period of rats is capable of promoting oxidative stress in the cerebellum with a decrease in Purkinje cell density and myelin basic protein compromise, which could be associated with functional motor impairments. In addition, although 10 mg F/L exposure promoted redox alterations, it did not affect other parameters evaluated, highlighting the safe use of F in low doses.

Effect of senescence on the tyrosine hydroxylase and S100B immunoreactivity in the nigrostriatal pathway of the rat.

Senescence is a natural and progressive physiological event that leads to a series of morphophysiological alterations in the organism. The brain is the most vulnerable organ to both structural and functional changes during this process. Dopamine is a key neurotransmitter for the proper functioning of the brain, directly involved in circuitries related with emotions, learning, motivation and reward. One of the main dopamine- producing nuclei is the substantia nigra pars compacta (SNpc), which establish connections with the striatum forming the so-called nigrostriatal pathway. S100B is a calcium binding protein mainly expressed by astrocytes, involved in both intracellular and extracellular processes, and whose expression is increased following injury in the nervous tissue, being a useful marker in altered status of central nervous system. The present study aimed to analyze the impact of senescence on the cells immunoreactive for tyrosine hydroxylase (TH) and S100B along the nigrostriatal pathway of the rat. Our results show an decreased expression of S100B+ cells in SNpc. In addition, there was a significant decrease in TH immunoreactivity in both projection fibers and TH+ cell bodies. In the striatum, a decrease in TH immunoreactivity was also observed, as well as an enlargement of the white matter bundles. Our findings point out that senescence is related to the anatomical and neurochemical changes observed throughout the nigrostriatal pathway.

Methylmercury exposure during prenatal and postnatal neurodevelopment promotes oxidative stress associated with motor and cognitive damages in rats: an environmental-experimental toxicology study.

The environmental contamination by methylmercury (MeHg) is a major concern for public health. The effects of MeHg in the central nervous system (CNS) of adult animals have been extensively investigated; however, little is known about the effects of MeHg exposure during intrauterine and lactation periods on motor and cognitive functions of adolescent rats. Therefore, this study aimed to investigate the effect of MeHg exposure during intrauterine life and lactation on both motor and cognitive functions of offspring rats. Ten female Wistar rats were exposed to 40 µg/kg/day of MeHg through cookie treats from the first day of pregnancy until the last day of breastfeeding. Both motor and cognitive functions of offspring male rats were assessed by open field, rotarod, and step-down inhibitory avoidance tests. Forty-one days after birth, the hippocampus and cerebellum were collected to determine total Hg content, antioxidant capacity against peroxyl radicals (ACAP), reduced glutathione (GSH) levels, lipid peroxidation (LPO), and nitrite levels. MeHg exposure during CNS development increased Hg levels in both hippocampal and cerebellar parenchymas, triggered oxidative stress throughout ACAP and GSH decrease, increased LPO and nitrite levels. These alterations resulted in reduced spontaneous and stimulated locomotion and short- and long-term memory deficits. Therefore, damages triggered by MeHg exposure during intrauterine life and lactation had detrimental effects on oxidative biochemistry and motor and cognitive functions of offspring rats.

Methylmercury Causes Neurodegeneration and Downregulation of Myelin Basic Protein in the Spinal Cord of Offspring Rats after Maternal Exposure.

Methylmercury (MeHg) is one of the most dangerous toxic pollutants spread throughout the earth. Chronic MeHg intoxication by contaminated food ingestion is the most common threat to human health, including impairment to the developing fetus. The present study aims at investigating the effects of maternal exposure to MeHg during gestation and lactation on the spinal cord of offspring. Pregnant rats received oral doses of MeHg (40 µg/kg/day) over a period of 42 days (21 gestation and 21 lactation). Control animals received the vehicle only. Total mercury concentration was measured in blood samples from offspring collected at the 41st postnatal day. Counting of motor neurons and immunoreactivity for myelin basic protein (MBP) were assessed in the spinal cords in both control and MeHg-intoxicated animals. Our results showed that MeHg promoted an increase in blood Hg levels. In addition, it caused a reduction in the number of spinal cord motor neurons as well as decreased MBP immunoreactivity in the cervical, thoracic and lumbar segments. Our present findings suggest that MeHg intoxication during rat pregnancy and lactation is associated with a pattern of motor neuron degeneration and downregulation of myelin basic protein in different segments of a developing spinal cord. Further studies are needed to establish the effect of MeHg intoxication in both young and adult rats.

Inflammatory Response and Secondary White Matter Damage to the Corpus Callosum after Focal Striatal Stroke in Rats.

Stroke is one of the leading causes of death and long-term disabilities worldwide, resulting in a debilitating condition occasioned by disturbances in the cerebral vasculature. Primary damage due to metabolic collapse is a quick outcome following stroke, but a multitude of secondary events, including excitotoxicity, inflammatory response, and oxidative stress cause further cell death and functional impairment. In the present work, we investigated whether a primary ischemic damage into the dorsal striatum may cause secondary damage in the circumjacent corpus callosum (CC). Animals were injected with endothelin-1 and perfused at 3, 7, 14, and 30 post-lesion days (PLD). Sections were stained with Cresyl violet for basic histopathology and immunolabeled by antibodies against astrocytes (anti-GFAP), macrophages/microglia (anti-IBA1/anti MHC-II), oligodendrocytes (anti-TAU) and myelin (anti-MBP), and Anti-Nogo. There were conspicuous microgliosis and astrocytosis in the CC, followed by later oligodendrocyte death and myelin impairment. Our results suggest that secondary white matter damage in the CC follows a primary focal striatal ischemia in adult rats.

Analysis of the 2020 Taal Volcano tephra fall deposits from crowdsourced information and field data.

After 43 years of dormancy, Taal Volcano violently erupted in January 2020 forming a towering eruption plume. The fall deposits covered an area of 8605 km2, which includes Metro Manila of the National Capital Region of the Philippines. The tephra fall caused damage to crops, traffic congestion, roof collapse, and changes in air quality in the affected areas. In a tropical region where heavy rains are frequent, immediate collection of data is crucial in order to preserve the tephra fall deposit record, which is readily washed away by surface water runoff and prevailing winds. Crowdsourcing, field surveys, and laboratory analysis of the tephra fall deposits were conducted to document and characterize the tephra fall deposits of the 2020 Taal Volcano eruption and their impacts. Results show that the tephra fall deposit thins downwind exponentially with a thickness half distance of about 1.40 km and 9.49 km for the proximal and distal exponential segments, respectively. The total calculated volume of erupted fallout deposit is 0.057 km3, 0.042 km3, or 0.090 km3 using the exponential, power-law, and Weibull models, respectively, and all translate to a VEI of 3. However, using a probabilistic approach (Weibull method) with 90% confidence interval, the volume estimate is as high as 0.097 km3. With the addition of the base surge deposits amounting to 0.019 km3, the volume translates to a VEI of 4, consistent with the classification for the observed height and umbrella radius of the 2020 main eruption plume. VEI 4 is also consistent with the calculated median eruption plume height of 17.8 km and sub-plinian classification based on combined analysis of isopleth and isopach data. Phreatomagmatic activity originated from a vent located in Taal Volcano's Main Crater Lake (MCL), which contained 42 million m3 of water. This eruptive style is further supported by the characteristics of the ash grain components of the distal 12 January 2020 tephra fall deposits, consisting dominantly of andesitic vitric fragments (83-90%). Other components of the fall deposits are lithic (7-11%) and crystal (less than 6%) grains. Further textural and geochemical analysis of these tephra fall deposits contributes to better understand the volcanic processes that occurred at Taal Volcano, one of the 16 Decade Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) because of its destructive nature and proximity to densely populated areas. The crowdsourcing initiative provided a significant portion of the data used for this study while at the same time educating and empowering the community to build resilience. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00445-022-01534-y.