Biology subjects

Garcia, A.

Publications and source records attributed to Garcia, A..

At least 73 records · Page 4Linked to original sources

bioRxiv2022

Duplication and overexpression of the genes encoding a beta 1,3-glucan synthase confer the intrinsic resistance to echinocandin in Mucor circinelloides

Procedures such as solid organ transplants and cancer treatments can leave many patients in an immunocompromised state resulting in an increased susceptibility to opportunistic diseases including fungal infections. Mucormycosis infections are continually emerging and pose a serious threat to immunocompromised patients. Currently there has been a sharp increase in mucormycosis cases as a secondary infection in patients battling SARS-CoV-2 infections. Mucorales fungi are notorious for presenting resistance to most antifungal drugs. The absence of effective means to treat these infections results in mortality rates approaching 100% in cases of disseminated infection. One of the most effective antifungal drug classes currently available are echinocandins. Echinocandins seem to be efficacious in treatment of many other fungal infections. Unfortunately, susceptibility testing has found that echinocandins have no to little effect on Mucorales. In this study, we found that the model Mucorales Mucor circinelloides genome carries three copies of the genes encoding for the echinocandin {beta}-(1,3)-D-glucan synthase (fksA, fksB, and fksC). Interestingly, we revealed that exposing M. circinelloides to micafungin significantly increased the expression of the fksA and fksB genes when compared to an untreated control. We further uncovered that the serine/threonine phosphatase calcineurin is responsible for the overexpression of fksA and fksB as deletion of calcineurin results in a decrease in expression of all three fks genes and a lower minimal inhibitory concentration (MIC) to micafungin. Taken together, this study demonstrates that the fks gene duplication and overexpression by calcineurin contribute to the intrinsic resistance to echinocandins in Mucor. IMPORTANCEThe recent emergence of mucormycosis cases in immunocompromised patients has become a more prevalent issue. The Mucorales fungi that cause these infections are known to be highly drug resistant, thus treatment options are limited and the mortalities of these types of infections remain unacceptably high. Echinocandins are one of the latest antifungal drugs developed to successfully treat fungal infections, but it remains unclear why Mucorales fungi are resistant to these treatments. In our study, we uncovered three copies of the genes (fks) encoding the drug target for echinocandins. Furthermore, we discovered that the serine-threonine phosphatase calcineurin is regulating the over-expression of these genes, which confers resistance. By inhibiting calcineurin we found that the expression of these drug targets decreases resulting in an increase in susceptibility to echinocandins both in vitro and in vivo

microbiology↗

bioRxiv2021

Novel regimens of bedaquiline-pyrazinamide combined with moxifloxacin, rifabutin, delamanid and/or OPC-167832 in murine tuberculosis models

A recent landmark trial showed a 4-month regimen of rifapentine, pyrazinamide, moxifloxacin and isoniazid (PZMH) to be non-inferior to the 6-month standard of care. Here, two murine models of tuberculosis were used to test whether novel regimens replacing rifapentine and isoniazid with bedaquiline and another drug would maintain or increase the sterilizing activity of the regimen. In BALB/c mice, replacing rifapentine in the PZM backbone with bedaquiline (i.e., BZM) significantly reduced both lung CFU counts after 1 month and the proportion of mice relapsing within 3 months after completing 1.5 months of treatment. Addition of rifabutin to BZM (BZMRb) further increased the sterilizing activity. In the C3HeB/FeJ mouse model characterized by caseating lung lesions, treatment with BZMRb resulted in significantly fewer relapses than PZMH after 2 months of treatment. A regimen combining the new DprE1 inhibitor OPC-167832 and delamanid (BZOD) also had superior bactericidal and sterilizing activity compared to PZM in BALB/c mice and was similar in efficacy to PZMH in C3HeB/FeJ mice. Thus, BZM represents a promising backbone for treatment-shortening regimens. Given the prohibitive drug-drug interactions between bedaquiline and rifampin or rifapentine, the BZMRb regimen represents the best opportunity to combine, in one regimen, the treatment-shortening potential of the rifamycin class with that of BZM and deserves high priority for evaluation in clinical trials. Other 4-drug BZM-based regimens and BZOD represent promising opportunities for extending the spectrum of treatment-shortening regimens to rifamycin- and fluoroquinolone-resistant tuberculosis.

microbiology↗

bioRxiv2021

A rapid prototyping approach for intensive field courses to build scientific and professional skills

This paper reports on the design and evaluation of Field Studies in Functional Ecology (FSFE), a two-week intensive residential field course that enables students to master core content in functional ecology alongside skills that facilitate their transition from student to scientist. This paper provides an overview of the course structure, showing how the constituent elements have been designed and refined over successive iterations of the course. We detail how FSFE students: 1. Work closely with discipline specialists to develop a small group project that tests an hypothesis to answer a genuine scientific question in the field; 2. Learn critical skills of data management and communication; and 3. Analyse, interpret and present their results in the format of a scientific symposium. This process is repeated in an iterative cognitive apprenticeship model, supported by a series of workshops that name and explicitly instruct the students in hard and soft skills critical relevant for research and other careers. FSFE students develop a coherent and nuanced understanding of how to approach and execute ecological studies. The sophisticated knowledge and ecological research skills that they develop during the course is demonstrated through high quality presentations and peer-reviewed publications in an open-access, student-led journal. We outline our course structure and evaluate its efficacy to show how this novel combination of field course elements allows students to gain maximum value from their educational journey, and to develop cognitive, affective and reflective tools to help apply their skills as scientists.

scientific communication and education↗

bioRxiv2021

LILRB1 and LILRB2 expression in peripheral blood immune cells at 18 and 24 months of age in infants born from mothers with placental malaria

BackgroundPlacental malaria (PM) is associated with a higher susceptibility of infants to Plasmodium falciparum (Pf) malaria. A hypothesis of immune tolerance has been suggested but no clear explanation has been provided so far. Our goal was to investigate the involvement of inhibitory receptors LILRB1 and LILRB2, known to drive immune evasion upon ligation with pathogen and/or host ligands, in PM-induced immune tolerance. MethodsInfants of mothers with or without PM were enrolled in Allada, southern Benin, and followed-up for 24 months. Antibodies with specificity for five blood stage parasite antigens were quantified by ELISA, and the frequency of immune cell subsets was quantified by flow cytometry. LILRB1 or LILRB2 expression was assessed on cells collected at 18 and 24 months of age. ResultsInfants born to PM-mothers had a higher risk of developing clinical malaria than those born to mothers without PM (IRR=1.53, p=0.040), and such infants displayed a lower frequency of non-classical monocytes (OR=0.74, p=0.01) that overexpressed LILRB2 (OR=1.36, p=0.002). Moreover, infants born to PM-mothers had lower levels of cytophilic IgG and higher levels of IL-10 during active infection. ConclusionModulation of IgG and IL-10 levels could impair monocyte functions (opsonisation/phagocytosis) in infants born to PM-mothers, possibly contributing to their higher susceptibility to malaria. The long-lasting effect of PM on infants monocytes was notable, raising questions about the capacity of ligands such as Rifins or HLA-I molecules to bind to LILRB1 and LILRB2 and to modulate immune responses, and about the reprogramming of neonatal monocytes/macrophages. KEY POINTSInfants of mothers with placental malaria were more susceptible to clinical malaria than those born to mothers without placental malaria and they displayed a lower frequency of non-classical monocytes that overexpressed LILRB2.

immunology↗

bioRxiv2021

Let-7b-5p, miR-184, and miR-22-3p: Multianalyte Plasma Biomarkers for NSCLC Diagnosis and for Predicting Resistance to Osimertinib

Low-dose computed tomography (LDCT) Non-Small Cell Lung (NSCLC) screening is associated with high false-positive rates, leading to unnecessary expensive and invasive follow ups. There is a need for minimally invasive approaches to improve the accuracy of NSCLC diagnosis. Plasma extracellular vesicle (EV) and circulating microRNA (miRNA) have been proposed as cancer screening biomarkers. However, the identification of highly sensitive and broadly predictive core miRNA signatures remains a challenge. Also, how these systemic and diverse miRNAs impact cancer drug response is not well understood. Using an integrative approach, we examined plasma EV and circulating miRNA isolated from NSCLC patients versus screening controls with a similar risk profile. We found that combining EV (Hsa-miR-184, Let-7b-5p) and circulating (Hsa-miR-22-3p) miRNAs abundance robustly discriminates between NSCLC patients and high-risk cancer-free controls. Diagnosed NSCLC patients harboring sensitizing mutations in epidermal growth factor receptor EGFR (T790M, L578R) are treated with Osimertinib, a potent tyrosine kinase inhibitor (TKI). Nearly all patients develop TKI resistance via complex mechanisms and progress. We found that Hsa-miR-22-3p, Hsa-miR-184, and Let-7b-5p functionally converge on WNT/{beta}catenin and mTOR/AKT signaling axes, known cancer therapy resistance signals. Targeting Hsa-miR-22-3p and Hsa-miR-184 desensitized EGFR-mutated (T790M, L578R) NSCLC cells to Osimertinib. These findings suggest that the expression levels of circulating hsa-miR-22-3p combined with EV hsa-miR-184 and Let-7b-5p levels potentially define a core biomarker signature for improving the accuracy of NSCLC diagnosis. Importantly, these biomarkers have the potential to enable prospective identification of patients who are at risk of responding poorly to Osimertinib alone but likely to benefit from Osimertinib/AKT blockade combination treatments.

cancer biology↗

bioRxiv2021

Complexity of brain dynamics as a correlate of consciousness in anaesthetized monkeys

The use of anaesthesia is a fundamental tool in the investigation of consciousness. Anesthesia procedures allow to investigate different states of consciousness from sedation to deep anesthesia within controlled scenarios. In this study we use information quantifiers to measure the complexity of electrocorticogram recordings in monkeys. We apply these metrics to compare different stages of general anesthesia for evaluating consciousness in several anesthesia protocols. We find that the complexity of brain activity can be used as a correlate of consciousness. For two of the anaesthetics used, propofol and medetomidine, we find that the anaesthetised state is accompanied by a reduction in the complexity of brain activity. On the other hand we observe that use of ketamine produces an increase in complexity measurements. We relate this observation with increase activity within certain brain regions associated with the ketamine used doses. Our measurements indicate that complexity of brain activity is a good indicator for a general evaluation of different levels of consciousness awareness, both in anesthetized and non anesthetizes states.

neuroscience↗

bioRxiv2021

Quantitation of human enteric viruses as alternative indicators of fecal pollution to evaluate wastewater treatment processes

We investigated the potential use and quantitation of human enteric viruses in municipal wastewater samples of Winnipeg (Manitoba, Canada) as alternative indicators of contamination and evaluated the processing stages of the wastewater treatment plant. During the fall 2019 and winter 2020 seasons, samples of raw sewage, activated sludge, effluents, and biosolids (sludge cake) were collected from the North End Sewage Treatment Plant (NESTP), which is the largest wastewater treatment plant in the City of Winnipeg. DNA and RNA enteric viruses, as well as the uidA gene found in Escherichia coli were targeted in the samples collected from the NESTP. Total nucleic acids from each wastewater treatment sample were extracted using a commercial spin-column kit. Enteric viruses were quantitated in the extracted samples via quantitative PCR using TaqMan assays. The average gene copies assessed in the raw sewage were not significantly different (p-values ranged between 0.0547 and 0.7986) than the average gene copies assessed in the effluents for Adenovirus and crAssphage (DNA viruses), Pepper Mild Mottle Virus (RNA virus), and uidA in terms of both volume and biomass. A significant reduction of these enteric viruses was observed consistently in activated sludge samples compared with those for raw sewage. Corresponding reductions in gene copies per volume and gene copies per biomass were also seen for uidA but were not statistically significant (p-value = 0.8769 and p-value = 0.6353, respectively). The higher gene copy numbers of enteric viruses and E. coli observed in the effluents may be associated with the 12-hour hydraulic retention time in the facility. Enteric viruses found in gene copy numbers were at least one order of magnitude higher than the E. coli marker uidA. This indicate that enteric viruses may survive the wastewater treatment process and viral-like particles are being released into the aquatic environment. Our results suggest that Adenovirus, crAssphage, and Pepper mild mottle virus can be used as complementary viral indicators of human fecal pollution.

microbiology↗

bioRxiv2021

AMP-Kinase mediates regulation of glomerular volume and podocyte survival

We reported that Shroom3 knockdown, via Fyn inhibition, induced albuminuria with foot process effacement (FPE) without glomerulosclerosis (FSGS) or podocytopenia. Interestingly, knockdown mice had reduced podocyte volumes. Human minimal change disease, where podocyte Fyn inactivation was reported, also showed lower glomerular volumes than FSGS. We hypothesized that lower glomerular volume prevented the progression to podocytopenia. To test this hypothesis, we utilized unilateral- and 5/6th nephrectomy models in Shroom3 knockdown mice. Knockdown mice exhibited lower glomerular volume, and less glomerular and podocyte hypertrophy after nephrectomy. FYN-knockdown podocytes had similar reductions in podocyte volume, implying Fyn was downstream of Shroom3. Using SHROOM3- or FYN-knockdown, we confirmed reduced podocyte protein content, along with significantly increased phosphorylated AMP-kinase, a negative regulator of anabolism. AMP-Kinase activation resulted from increased cytoplasmic redistribution of LKB1 in podocytes. Inhibition of AMP-Kinase abolished the reduction in glomerular volume and induced podocytopenia in mice with FPE, suggesting a protective role for AMP-Kinase activation. In agreement with this, treatment of glomerular injury models with AMP-Kinase activators restricted glomerular volume, podocytopenia and progression to FSGS. In summary, we demonstrate the important role of AMP-Kinase in glomerular volume regulation and podocyte survival. Our data suggest that AMP-Kinase activation adaptively regulates glomerular volume to prevent podocytopenia in the context of podocyte injury.

systems biology↗

bioRxiv2020

Naa12 rescues embryonic lethality in Naa10-Deficient Mice in the amino-terminal acetylation pathway

Amino-terminal acetylation is catalyzed by a set of N-terminal acetyltransferases (NATs). The NatA complex (including X-linked Naa10 and Naa15) is the major acetyltransferase, with 40-50% of all mammalian proteins being potential substrates. However, the overall role of amino-terminal acetylation on a whole-organism level is poorly understood, particularly in mammals. Male mice lacking Naa10 show no globally apparent in vivo amino-terminal acetylation impairment and do not exhibit complete embryonic lethality. Rather Naa10 nulls display increased neonatal lethality, and the majority of surviving undersized mutants exhibit a combination of hydrocephaly, cardiac defects, homeotic anterior transformation, piebaldism and urogenital anomalies. Naa12 is a previously unannotated Naa10-like paralogue with NAT activity that genetically compensates for Naa10. Mice deficient for Naa12 have no apparent phenotype, whereas mice deficient for Naa10 and Naa12 display embryonic lethality. The discovery of Naa12 adds to the currently known machinery involved in amino-terminal acetylation in mice.

developmental biology↗

bioRxiv2020

Non-permissive human conventional CD1c+ dendritic cells enable trans-infection of human primary renal tubular epithelial cells and protect BK polyomavirus from neutralization

The BK polyomavirus (BKPyV) is a ubiquitous human virus that persists in the renourinary epithelium. Immunosuppression can lead to BKPyV reactivation in the first year post-transplantation in kidney (KTR) and hematopoietic stem cell transplant recipients. In KTR, persistent DNAemia has been correlated to the occurrence of polyomavirus-associated nephropathy (PVAN) that can lead to graft loss if not properly controlled. Based on recent observations that conventional dendritic cells (cDC) specifically infiltrate PVAN lesions, we hypothesized that those cells could play a role in BKPyV infection. We first demonstrated that monocyte-derived DC (MDDC), an in vitro model for mDC, captured BKPyV particles through an unconventional GRAF-1 endocytic pathway. Neither BKPyV particles nor BKPyV-infected cells were shown to activate MDDC. Endocytosed virions were efficiently transmitted to permissive cells and shown to be protected from the antibody-mediated neutralization. Finally, we demonstrated that freshly isolated CD1c+ mDC from the blood and kidney parenchyma behaved similarly to MDDC thus extending our results to cells of clinical relevance. This study sheds light on a potential unprecedented CD1c+ mDC involvement in the BKPyV infection as a promoter of viral spreading.

microbiology↗

bioRxiv2020

Lateral Hypothalamic GABAergic neurons encode and potentiate sucrose palatability

Sucrose is attractive to most species in the animal kingdom, not only because it induces a sweet taste sensation but also for its positive palatability (i.e., oromotor responses elicited by increasing sucrose concentrations). Although palatability is such an important sensory attribute, it is currently unknown which cell types encode and modulate sucroses palatability. Studies in mice have shown that activation of GABAergic LHAVgat+ neurons evokes voracious eating; however, it is not known whether these neurons would be driving consumption by increasing palatability. Using optrode recordings, we measured sucroses palatability while VGAT-ChR2 transgenic mice performed a brief access sucrose test. We found a subpopulation of LHAVgat+ neurons encodes palatability by increasing (or decreasing) their activity as a function of the increment in licking responses evoked by sucrose concentrations. Optogenetic gain of function experiments, where mice were able to choose among available water, 3%, or 18% sucrose solution, uncovered that opto-stimulation of LHAVgat+ neurons consistently promoted higher intake of the most palatable stimulus (18% sucrose). In contrast, if they self-stimulated near the less palatable stimulus, some VGAT-ChR2 mice preferred water over 18% sucrose. Unexpectedly, activation of LHAVgat+ neurons increased quinine intake but only during water deprivation, since in sated animals, they failed to promote quinine intake or tolerate an aversive stimulus. Conversely, these neurons promoted overconsumption of sucrose when it was the nearest stimulus. Also, experiments with solid foods further confirmed that these neurons increased food interaction time with the most palatable food available. We conclude that LHAVgat+ neurons increase the drive to consume, but it is potentiated by the palatability and proximity of the tastant.

neuroscience↗

bioRxiv2020

The mutational landscape of human olfactory G protein-coupled receptors

Olfactory receptors (ORs) constitute a large family of sensory proteins that enable us to recognize a wide range of chemical volatiles in the environment. By contrast to the extensive information about human olfactory thresholds for thousands of odorants, studies of the genetic influence on olfaction are limited to a few examples. Here, we analyzed a compendium of 118,057 natural variants in human ORs collected from the public domain. OR mutations were categorized depending on their genomic and protein contexts, as well as their frequency of occurrence in several human populations. Functional interpretation of the natural changes was estimated from the increasing knowledge of the structure and function of the G protein-coupled receptor (GPCR) family, to which ORs belong. Our analysis reveals an extraordinary diversity of natural variations in the olfactory gene repertoire between individuals and populations, with a significant number of changes occurring at structural conserved regions. A particular attention is paid to mutations in positions linked to the conserved GPCR activation mechanism that could imply phenotypic variation in the olfactory perception. An interactive web application (available at http://lmc.uab.cat/hORMdb) was developed for the management and visualization of this mutational dataset.

bioinformatics↗

bioRxiv2020

The AMPK-related kinase NUAK1 controls cortical axons branching though a local modulation of mitochondrial metabolic functions

The precise regulation of the cellular mechanisms underlying axonal morphogenesis is essential to the formation of functional neuronal networks. We previously identified the autism-candidate kinase NUAK1 as a central regulator of axon branching in mouse cortical neurons through the control of mitochondria trafficking. How does local mitochondrial position or function regulate axon branching during development? Here, we characterized the metabolic regulation in the developing axon and report a marked metabolic decorrelation between axon elongation and collateral branching. We next solved the cascade of event leading to presynaptic clustering and mitochondria recruitment during spontaneous branch formation. Interestingly and contrary to peripheral neurons, mitochondria are recruited after but not prior to branch formation in cortical neurons. Using flux metabolomics and fluorescent biosensors, we observed that NUAK1 deficiency significantly impairs mitochondrial metabolism and axonal ATP concentration. Upregulation of mitochondrial function is sufficient to rescue axonal branching in NUAK1 null neurons in vitro and in vivo. Altogether, our results indicate that NUAK1 exerts a dual function during axon branching through its ability to control mitochondria distribution and activity, and suggest that a mitochondrial-dependent remodeling of local metabolic homeostasis plays a critical role during axon morphogenesis.

neuroscience↗

bioRxiv2020

Anodal transcranial direct-current stimulation over the left dorsolateral prefrontal cortex and perception of emotional faces

The prefrontal cortices have been shown to be engaged in the perception of emotional faces, and imaging studies correlate activation of the left dorsolateral prefrontal cortex (l-DLPFC) with correct identification of emotional expressions. Transcranial direct current stimulation (tDCS)has been shown to modulate cortical function and might influence the perception of emotional faces. Our aim was to evaluate the possible effects of tDCS on a task that required correct identification of emotions represented by human faces presented on a screen. Ten volunteers (ages 18-30; mean = 23.2; SD = 4.3) were evaluated. The experiments were carried out in two 20 minutes stimulation sessions (real and sham tDCS) 4 days apart, at least, to avoid carryover effects, and session orders were randomized. The anode was placed over the l-DLPFC (F3 of the international 10-20 EEG electrode positioning system) and the cathode over the contralateral supraorbital region. Emotional stimuli were 120 consecutive human faces to be verbally classified as "happy", "surprised", "neutral", "angry" or "sad". Real anodal tDCS over the l-DLPFC resulted in significantly longer response times with a trend towards increased error rates, compared to the sham condition.

neuroscience↗

bioRxiv2020

Fine-scale genomic analyses of admixed individuals reveal unrecognized genetic ancestry components in Argentina

Similarly to other populations across the Americas, Argentinean populations trace back their genetic ancestry into African, European and Native American ancestors, reflecting a complex demographic history with multiple migration and admixture events in pre- and post-colonial times. However, little is known about the sub-continental origins of these three main ancestries. We present new high-throughput genotyping data for 87 admixed individuals across Argentina. This data was combined to previously published data for admixed individuals in the region and then compared to different reference panels specifically built to perform population structure analyses at a sub-continental level. Concerning the Native American ancestry, we could identify four Native American components segregating in modern Argentinean populations. Three of them are also found in modern South American populations and are specifically represented in Central Andes, Central Chile/Patagonia, and Subtropical and Tropical Forests geographic areas. The fourth component might be specific to the Central Western region of Argentina, and it is not well represented in any genomic data from the literature. As for the European and African ancestries, we confirmed previous results about origins from Southern Europe, Western and Central Western Africa, and we provide evidences for the presence of Northern European and Eastern African ancestries. Author SummaryThe human genetic diversity in Argentina reflects demographic processes during which the European colonists invaded a territory where Native American populations were settled. During the colonial period, the slave trade also prompted many African people to move to Argentina. Little is known about the origins of these three continental ancestry components in Argentinean populations nowadays. Genotyping data for 87 admixed individuals throughout Argentina was generated and data from the literature was re-analyzed to shed light on this question. We confirmed that most of the European genetic ancestry comes from the South, although several individuals are related to Northern Europeans. We confirmed that the African origins in Argentina mainly trace back from Western and Central/Western regions, and we document some proportion of Eastern African origins poorly described before. As for the Native American ancestry, we identified that it can be divided into four main components that correspond to Central Chile/Patagonia, Subtropical and Tropical Forests, Central Andes and Central Western region of Argentina. In order to understand the specificity of the genetic diversity in Argentina, more effort is required to generate specific massive genomic knowledge at the local level.

genetics↗

bioRxiv2020

Is cathodal prefrontal transcranial direct current stimulation capable of affecting inhibitory control and sustained attention? A single-blind, crossover,sham-controlled study

BackgroundAnodal transcranial direct current stimulation (a-tDCS) has been shown to promote performance improvement of normal individuals in tests of executive function, including tasks that demand sustained attention and inhibitory control. The presumed mechanism is facilitation of prefrontal cortex activation, since a-tDCS is thought to increase cortical excitability. Only a few studies, however, have investigated the effects of inhibitory, cathodal tDCS (c-tDCS) on cognitive tasks, and reported results are often inconsistent. Studies about the effects of c-tDCS upon accuracy and reaction times are particularly scant. Objective/HypothesisThis study assessed the effects of inhibitory c-tDCS over the left dorsolateral prefrontal cortex (l-DLPFC) on the performance of neurologically intact young adults in Stroop and reaction time tests. MethodsSeventeen healthy undergraduate students (ten women) performed Stroop and reaction time tasks after delivery of c-tDCS (1 mA, 20 min) over l-DLFPC or a sham session. All subjects underwent both real and sham sessions, which were separated by an interval of one week. We hypothesized that c-tDCS might lead to an impairment of inhibitory control and attention abilities. ResultsWe found an interference effect on the Stroop task and also a ceiling effect on the reaction Time task. There were no statistically significant performance differences in any of the neuropsychological tests as a function of stimulation condition and/or subject gender. ConclusionsC-tDCS over the l-DLPFC of neurologically intact young individuals did not affect performance in Stroop Test accuracy or in reaction times, irrespective of subject gender. These results raise the possibility that c-tDCS inhibitory effects, well documented for the primary motor area, do not necessarily apply to higher order associative areas. The assumption that c-tDCS has inhibitory effects upon any cortical area, common in clinical trials, should be made with caution.

neuroscience↗

bioRxiv2019

Treatment with β3 adrenergic agonists reverses impaired cardiac myocyte Na+ export and improves severely decompensated heart failure; a clinical application of an experimental finding

BackgroundReported one- and two-year mortality for patients with advanced heart failure (HF) treated medically are ~75% and nearly 100%. In such patients, reversible cellular abnormalities are potential treatment targets and a raised cytosolic Na+ concentration that impairs their myocardial contractility is one potential target. {beta}3 adrenoceptor ({beta}3 AR) agonists stimulate the myocyte Na+-K+ pump. MethodsWe induced severe HF in rabbits by coronary ligation and measured indices of organ congestion after treatment with {beta}3 AR agonists. Na+-K+ pump current was measured in voltage-clamped myocytes isolated from non-infarct myocardium. To assess if {beta}3 ARs might add benefit to optimised guideline-directed medical treatment we report outcomes of giving the {beta}3 AR agonist mirabegron to patients hospitalized with advanced, treatment-refractory stage D HF. ResultsTreatment of rabbits after coronary ligation with {beta}3 AR agonist reversed a decreased myocyte Na+-K+ pump current and significantly reduced organ congestion and prevalence of ascites. Oral treatment with mirabegron rapidly improved signs and symptoms of 9 patients with advanced HF and improvement of [≥]1 NYHA Class was maintained early post-discharge with continued treatment. One patient died from HF at 16 months, 4 died from other causes at 2 - 30 months and 4 remain alive at 38 {+/-} 4 months with NYHA Class II symptoms. ConclusionsParallel {beta}3 AR agonist-induced reversal of Na+-K+ pump inhibition and severe HF in rabbits identify pump inhibition as a treatment target, and changed in-hospital clinical trajectory and post-discharge course more favorable than expected suggest efficacy of mirabegron in advanced human HF.

physiology↗

bioRxiv2019

Early developmental exposure to Fluoxetine and Citalopram results in different neurodevelopmental outcomes

Although selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for prenatal depression, there exists controversy over the adverse effects of SSRI use on fetal development. Few studies have adequately isolated outcomes due to SSRI exposure and those due to maternal psychiatric conditions. Here, we directly investigated the outcomes of exposure to widely-used SSRIs fluoxetine and citalopram on the developing nervous system of Xenopus laevis tadpoles, using an integrative experimental approach. We exposed tadpoles to low doses of citalopram and fluoxetine during a critical developmental period and found that the different groups of tadpoles displayed opposing behavioral effects. While both groups showed reduced schooling behavior, the fluoxetine group showed increased seizure susceptibility and reduced startle habituation. In contrast, the citalopram treated tadpoles had decreased seizure susceptibility and increased habituation. Both groups had abnormal dendritic morphology in the optic tectum, a brain area important for all three behaviors tested. Whole-cell electrophysiological recordings of tectal neurons showed no differences in synaptic function across groups; however, tectal cells from fluoxetine-treated tadpoles had decreased voltage gated K+ currents while cells in the citalopram group had increased K+ currents. Both the behavior and electrophysiological findings indicate that cells and circuits in the fluoxetine treated optic tecta are hyperexcitable, while the citalopram group exhibits decreased excitability. Taken all together, these results show that early developmental exposure to SSRIs is sufficient to induce neurodevelopmental effects, however these effects can be complex and vary depending on the SSRI used. This may explain some of the discrepancies across human studies, and further underscores the importance of serotonergic signaling for the developing nervous system.

neuroscience↗