Presynaptic Mechanisms of Lead Neurotoxicity: Effects on Vesicular Release, Vesicle Clustering and Mitochondria Number

Childhood lead (Pb2+) intoxication is a global public health problem and accounts for 0.6% of the global burden of disease associated with intellectual disabilities. Despite the recognition that childhood Pb2+ intoxication contributes significantly to intellectual disabilities, there is a fundamental lack of knowledge on presynaptic mechanisms by which Pb2+ disrupts synaptic function. In this study, using a well-characterized rodent model of developmental Pb2+ neurotoxicity, we show that Pb2+ exposure markedly inhibits presynaptic vesicular release in hippocampal Schaffer collateral-CA1 synapses in young adult rats. This effect was associated with ultrastructural changes which revealed a reduction in vesicle number in the readily releasable/docked vesicle pool, disperse vesicle clusters in the resting pool, and a reduced number of presynaptic terminals with multiple mitochondria with no change in presynaptic calcium influx. These studies provide fundamental knowledge on mechanisms by which Pb2+ produces profound inhibition of presynaptic vesicular release that contribute to deficits in synaptic plasticity and intellectual development

Increasing Maternal or Post-Weaning Folic Acid Alters Gene Expression and Moderately Changes Behavior in the Offspring

Background Studies have indicated that altered maternal micronutrients and vitamins influence the development of newborns and altered nutrient exposure throughout the lifetime may have potential health effects and increased susceptibility to chronic diseases. In recent years, folic acid (FA) exposure has significantly increased as a result of mandatory FA fortification and supplementation during pregnancy. Since FA modulates DNA methylation and affects gene expression, we investigated whether the amount of FA ingested during gestation alters gene expression in the newborn cerebral hemisphere, and if the increased exposure to FA during gestation and throughout the lifetime alters behavior in C57BL/6J mice. Methods Dams were fed FA either at 0.4 mg or 4 mg/kg diet throughout the pregnancy and the resulting pups were maintained on the diet throughout experimentation. Newborn pups brain cerebral hemispheres were used for microarray analysis. To confirm alteration of several genes, quantitative RT-PCR (qRT-PCR) and Western blot analyses were performed. In addition, various behavior assessments were conducted on neonatal and adult offspring. Results Results from microarray analysis suggest that the higher dose of FA supplementation during gestation alters the expression of a number of genes in the newborns’ cerebral hemispheres, including many involved in development. QRT-PCR confirmed alterations of nine genes including down-regulation of Cpn2, Htr4, Zfp353, Vgll2 and up-regulation of Xist, Nkx6-3, Leprel1, Nfix, Slc17a7. The alterations in the expression of Slc17a7 and Vgll2 were confirmed at the protein level. Pups exposed to the higher dose of FA exhibited increased ultrasonic vocalizations, greater anxiety-like behavior and hyperactivity. These findings suggest that although FA plays a significant role in mammalian cellular machinery, there may be a loss of benefit from higher amounts of FA. Unregulated high FA supplementation during pregnancy and throughout the life course may have lasting effects, with alterations in brain development resulting in changes in behavior

Characterization of Induced Pluripotent Stem Cell Microvesicle Genesis, Morphology and Pluripotent Content

Microvesicles (MVs) are lipid bilayer-covered cell fragments that range in diameter from 30 nm–1uM and are released from all cell types. An increasing number of studies reveal that MVs contain microRNA, mRNA and protein that can be detected in the extracellular space. In this study, we characterized induced pluripotent stem cell (iPSC) MV genesis, content and fusion to retinal progenitor cells (RPCs) in vitro. Nanoparticle tracking revealed that iPSCs released approximately 2200 MVs cell/hour in the first 12 hrs with an average diameter of 122 nm. Electron and light microscopic analysis of iPSCs showed MV release via lipid bilayer budding. The mRNA content of iPSC MVs was characterized and revealed the presence of the transcription factors Oct-3/4, Nanog, Klf4, and C-Myc. The protein content of iPSCs MVs, detected by immunogold electron microscopy, revealed the presence of the Oct-3/4 and Nanog. Isolated iPSC MVs were shown to fuse with RPCs in vitro at multiple points along the plasma membrane. These findings demonstrate that the mRNA and protein cargo in iPSC MVs have established roles in maintenance of pluripotency. Building on this work, iPSC derived MVs may be shown to be involved in maintaining cellular pluripotency and may have application in regenerative strategies for neural tissue

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

TSPO Finds NOX2 in Microglia for Redox Homeostasis

During the past decade, Translocator Protein 18 kDa (TSPO), previously named peripheral benzodiazepine receptor, has gained a great deal of attention based on its use as a clinical biomarker of neuroinflammation with therapeutic potential. However, there is a paucity of knowledge on the function(s) of TSPO in glial cells. Here, we identify a novel function of TSPO in microglia that is not associated with steroidogenesis. We propose a TSPO interaction with NADPH Oxidase linking the generation of reactive oxygen species (ROS) signaling to the induction of an antioxidant response to maintain redox homeostasis. This line of investigation may provide a greater understanding of TSPO glial cell biology and the knowledge gained may prove beneficial in devising therapeutic strategies

Chronic early life lead (Pb2+) exposure alters presynaptic vesicle pools in hippocampal synapses

BACKGROUND: Lead (Pb(2+)) exposure has been shown to impair presynaptic neurotransmitter release in both in vivo and in vitro model systems. The mechanism by which Pb(2+) impairs neurotransmitter release has not been fully elucidated. In previous work, we have shown that Pb(2+) exposure inhibits vesicular release and reduces the number of fast-releasing sites in cultured hippocampal neurons. We have also shown that Pb(2+) exposure inhibits vesicular release and alters the distribution of presynaptic vesicles in Shaffer Collateral – CA1 synapses of rodents chronically exposed to Pb(2+) during development. METHODS: In the present study, we used transmission electron microscopy to examine presynaptic vesicle pools in Mossy Fiber-CA3 synapses and in Perforant Path-Dentate Gyrus synapses of rats to determine if in vivo Pb(2+) exposure altered presynaptic vesicle distribution in these hippocampal regions. Data were analyzed using T-test for each experimental endpoint. RESULTS: We found that Pb(2+) exposure significantly reduced the number of vesicles in the readily releasable pool and recycling pool in Mossy Fiber-CA3 terminals. In both Mossy Fiber-CA3 terminals and in Perforant Path-Dentate Gyrus terminals, Pb(2+) exposure significantly increased vesicle nearest neighbor distance in all vesicular pools (Rapidly Releasable, Recycling and Resting). We also found a reduction in the size of the postsynaptic densities of CA3 dendrites in the Pb(2+) exposed group. CONCLUSIONS: In our previous work, we have demonstrated that Pb(2+) exposure impairs vesicular release in Shaffer Collateral - CA1 terminals of the hippocampus and that the number of docked vesicles in the presynaptic active zone was reduced. Our current data shows that Pb(2+) exposure reduces the number of vesicles that are in proximity to release sites in Mossy Fiber- CA3 terminals. Furthermore, Pb(2+) exposure causes presynaptic vesicles to be further from one another, in both Mossy Fiber- CA3 terminals and in Perforant Pathway – Dentate Gyrus terminals, which may interfere with vesicle movement and release. Our findings provide a novel in vivo mechanism by which Pb(2+) exposure impairs vesicle dynamics and release in the hippocampus

Characterization of Induced Pluripotent Stem Cell Microvesicle Genesis, Morphology and Pluripotent Content

Microvesicles (MVs) are lipid bilayer-covered cell fragments that range in diameter from 30 nm-1 uM and are released from all cell types. An increasing number of studies reveal that MVs contain microRNA, mRNA and protein that can be detected in the extracellular space. In this study, we characterized induced pluripotent stem cell (iPSC) MV genesis, content and fusion to retinal progenitor cells (RPCs) in vitro. Nanoparticle tracking revealed that iPSCs released approximately 2200 MVs cell/hour in the first 12 hrs with an average diameter of 122 nm. Electron and light microscopic analysis of iPSCs showed MV release via lipid bilayer budding. The mRNA content of iPSC MVs was characterized and revealed the presence of the transcription factors Oct-3/4, Nanog, Klf4, and C-Myc. The protein content of iPSCs MVs, detected by immunogold electron microscopy, revealed the presence of the Oct-3/4 and Nanog. Isolated iPSC MVs were shown to fuse with RPCs in vitro at multiple points along the plasma membrane. These findings demonstrate that the mRNA and protein cargo in iPSC MVs have established roles in maintenance of pluripotency. Building on this work, iPSC derived MVs may be shown to be involved in maintaining cellular pluripotency and may have application in regenerative strategies for neural tissue.S

Selective map-following navigation deficit: a new case of developmental topographical disorientation

Introduction: Developmental topographical disorientation (DTD) is a lifelong condition in which affected individuals are selectively impaired in navigating space. Although it seems that DTD is widespread in the population, only a few cases have been studied from both a behavioral and a neuroimaging point of view. Here, we report a new case of DTD, never described previously, of a young woman (C.F.) showing a specific deficit in translating allocentrically coded information into egocentrically guided navigation, in presence of spared ability of constructing such representations. Method: A series of behavioral experiments was performed together with a resting-state functional magnetic resonance imaging (fMRI). Results: We demonstrated that C.F. was fully effective in learning and following routes and in building up cognitive maps as well as in recognizing landmarks. C.F.’s navigational skills, instead, dropped drastically in the map-following task when she was required to use a map to navigate in a novel environment. The rs-fMRI experiment demonstrated aberrant functional connectivity between regions within the default-mode network (DMN), and in particular between medial prefrontal cortex and posterior cingulate, medial parietal, and temporal cortices. Discussion: Our results would suggest that, at least in C.F., dysfunctional coactivation of core DMN regions would interfere with the ability to exploit cognitive maps for real-life navigation even when these maps can be correctly built

Normative data for the hayling and brixton tests in an italian population

Objective: The Hayling and Brixton tests constitute a short test battery that quickly assesses verbal and spatial inhibition and flexibility. This battery has shown high construct validity and strong reliability in clinical and experimental settings. The aim of this study was to develop an Italian version of the Hayling and Brixton tests and obtain normative values. Method: We collected normative data from 301 healthy Italian participants aged between 16 and 94 years, taking into account all demographics. To maximize the sample size, we used the overlapping interval strategy. Adjusted scores for demographics were obtained by linear regression analysis. Results: The performance on the Hayling and Brixton tests was influenced by age and education. In particular, age affected verbal accuracy and response time on the Hayling Sentence Completion Test, whereas education only affected the former. Differently, the spatial component, as measured by the Brixton Spatial Anticipation Test, was shaped only by age, which decreased the number of correct responses. Conclusions: Our study provides normative data that have been adjusted for relevant demographics and percentile grids in an Italian population. Our data support the use of the Hayling and Brixton tests as a valid instrument for performing neuropsychological evaluations and longitudinal analyses of executive functions in clinical practice and for research purpose