Neural conditional ablation of the protein tyrosine phosphatase receptor Delta PTPRD impairs gliogenesis in the developing mouse brain cortex

Neurodevelopmental disorders are characterized by alterations in the development of the cerebral cortex, including aberrant changes in the number and function of neural cells. Although neurogenesis is one of the most studied cellular processes in these pathologies, little evidence is known about glial development. Genetic association studies have identified several genes associated with neurodevelopmental disorders. Indeed, variations in the PTPRD gene have been associated with numerous brain disorders, including autism spectrum disorder, restless leg syndrome, and schizophrenia. We previously demonstrated that constitutive loss of PTPRD expression induces significant alterations in cortical neurogenesis, promoting an increase in intermediate progenitors and neurons in mice. However, its role in gliogenesis has not been evaluated. To assess this, we developed a conditional knockout mouse model lacking PTPRD expression in telencephalon cells. Here, we found that the lack of PTPRD in the mouse cortex reduces glial precursors, astrocytes, and oligodendrocytes. According to our results, this decrease in gliogenesis resulted from a reduced number of radial glia cells at gliogenesis onset and a lower gliogenic potential in cortical neural precursors due to less activation of the JAK/STAT pathway and reduced expression of gliogenic genes. Our study shows PTPRD as a regulator of the glial/neuronal balance during cortical neurodevelopment and highlights the importance of studying glial development to understand the etiology of neurodevelopmental diseases.

Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite

BACKGROUND

Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo.

RESULTS

This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion.

CONCLUSIONS

We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen-independent anaerobic process.

LAR Receptor Tyrosine Phosphatase Family in Healthy and Diseased Brain

Protein phosphatases are major regulators of signal transduction and they are involved in key cellular mechanisms such as proliferation, differentiation, and cell survival. Here we focus on one class of protein phosphatases, the type IIA Receptor-type Protein Tyrosine Phosphatases (RPTPs), or LAR-RPTP subfamily. In the last decade, LAR-RPTPs have been demonstrated to have great importance in neurobiology, from neurodevelopment to brain disorders. In vertebrates, the LAR-RPTP subfamily is composed of three members: PTPRF (LAR), PTPRD (PTPδ) and PTPRS (PTPσ), and all participate in several brain functions. In this review we describe the structure and proteolytic processing of the LAR-RPTP subfamily, their alternative splicing and enzymatic regulation. Also, we review the role of the LAR-RPTP subfamily in neural function such as dendrite and axon growth and guidance, synapse formation and differentiation, their participation in synaptic activity, and in brain development, discussing controversial findings and commenting on the most recent studies in the field. Finally, we discuss the clinical outcomes of LAR-RPTP mutations, which are associated with several brain disorders.

Comparative Efficacy of a High-Dose vs Standard-Dose Hepatitis B Revaccination Schedule Among Patients With HIV: A Randomized Clinical Trial

IMPORTANCE

Active immunization for hepatitis B virus (HBV) infection is recommended in patients living with HIV. Limited evidence is available about the most appropriate regimen of HBV vaccination among those who have not responded to an initial schedule.

OBJECTIVE

To determine the efficacy of a high-dose schedule compared with a standard dose of HBV vaccination.

DESIGN, SETTING, AND PARTICIPANTS

This double-masked, parallel-group, randomized controlled trial included patients living with HIV at a single outpatient HIV and hepatology clinic in Chile for whom previous HBV vaccination had failed. Patients with hepatitis B surface antibody (anti-HBs) titers less than 10 IU/L after an initial HBV vaccination regimen were included. Consecutive patients were recruited between December 2013 and March 2018. Data were analyzed in June 2018 using intention-to-treat analysis.

INTERVENTION

The high-dose HBV vaccination group consisted of 3 doses of 40 μg recombinant hepatitis B vaccine at 0, 1, and 2 months. The standard-dose group received 3 doses 20 μg each at 0, 1, and 2 months.

MAIN OUTCOMES AND MEASURES

Primary outcome was the serologic response to HBV vaccination (anti-HBs greater than 10 IU/L) 4 to 8 weeks after completion of the schedule. Secondary outcomes were anti-HBs greater than 100 IU/L and seroprotective anti-HBs at 1 year follow up.

RESULTS

A total of 107 patients underwent randomization (55 to the standard-dose group, 52 to the high-dose group); 81 (75.7%) were men, and the mean (SD) patient age was 47.0 (13.3) years. Nearly all patients were receiving antiretroviral therapy (105 patients [98%]) and 92 patients (86%) had an undetectable HIV viral load. Mean (SD) CD4 count was 418 (205) cells/mm3. There were no differences in baseline characteristics between groups. Serological response in the high-dose group was found in 36 of 50 patients (72%; 95% CI, 56.9%-82.9%) compared with 28 of 55 patients in the standard-dose group (51%; 95% CI, 37.1%-64.6%) (odds ratio, 2.48; 95% CI, 1.02-6.10; P = .03). Mean (SD) anti-HB levels were 398.0 (433.4) IU/L in the high-dose group and 158.5 (301.4) IU/L in the standard-dose group (P < .001). Of patients with a serological response in the high-dose group, 29 of 36 (80.6%) had anti-HBs titers greater than 100 IU/L compared with 14 of 28 responders (50.0%) in the standard-dose group (P = .02). At 1-year follow-up, 20 of 25 patients (80.0%) with a serological response in the high-dose group had protective anti-HBs vs 9 of 23 patients (39.1%) in the standard-dose group (P = .01).

CONCLUSIONS AND RELEVANCE

The results of this randomized clinical trial suggest that use of a high-dose regimen for HBV revaccination for patients with HIV achieves a higher and longer-lasting serological response as compared with a standard-dose regimen.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02003703.

The Protein Tyrosine Phosphatase Receptor Delta Regulates Developmental Neurogenesis

PTPRD is a receptor protein tyrosine phosphatase that is genetically associated with neurodevelopmental disorders. Here, we asked whether Ptprd mutations cause aberrant neural development by perturbing neurogenesis in the murine cortex. We show that loss of Ptprd causes increases in neurogenic transit-amplifying intermediate progenitor cells and cortical neurons and perturbations in neuronal localization. These effects are intrinsic to neural precursor cells since acute Ptprd knockdown causes similar perturbations. PTPRD mediates these effects by dephosphorylating receptor tyrosine kinases, including TrkB and PDGFRβ, and loss of Ptprd causes the hyperactivation of TrkB and PDGFRβ and their downstream MEK-ERK signaling pathway in neural precursor cells. Moreover, inhibition of aberrant TrkB or MEK activation rescues the increased neurogenesis caused by knockdown or homozygous loss of Ptprd. These results suggest that PTPRD regulates receptor tyrosine kinases to ensure appropriate numbers of intermediate progenitor cells and neurons, suggesting a mechanism for its genetic association with neurodevelopmental disorders.

Understanding gold toxicity in aerobically-grown Escherichia coli

Background

There is an emerging field to put into practice new strategies for developing molecules with antimicrobial properties. In this line, several metals and metalloids are currently being used for these purposes, although their cellular effect(s) or target(s) in a particular organism are still unknown. Here we aimed to investigate and analyze Au³⁺ toxicity through a combination of biochemical and molecular approaches.

Results

We found that Au³⁺ triggers a major oxidative unbalance in Escherichia coli, characterized by decreased intracellular thiol levels, increased superoxide concentration, as well as by an augmented production of the antioxidant enzymes superoxide dismutase and catalase. Because ROS production is, in some cases, associated with metal reduction and the concomitant generation of gold-containing nanostructures (AuNS), this possibility was evaluated in vivo and in vitro.

Conclusions

Au³⁺ is toxic for E. coli because it triggers an unbalance of the bacterium’s oxidative status. This was demonstrated by using oxidative stress dyes and antioxidant chemicals as well as gene reporters, RSH concentrations and AuNS generation.

The Role of the Rodent Insula in Anxiety

The human insula has been consistently reported to be overactivated in all anxiety disorders, activation which has been suggested to be proportional to the level of anxiety and shown to decrease with effective anxiolytic treatment. Nonetheless, studies evaluating the direct role of the insula in anxiety are lacking. Here, we set out to investigate the role of the rodent insula in anxiety by either inactivating different insular regions via microinjections of glutamatergic AMPA receptor antagonist CNQX or activating them by microinjection of GABA receptor antagonist bicuculline in rats, before measuring anxiety-like behavior using the elevated plus maze. Inactivation of caudal and medial insular regions induced anxiogenic effects, while their activation induced anxiolytic effects. In contrast, inactivation of more rostral areas induced anxiolytic effects and their activation, anxiogenic effects. These results suggest that the insula in the rat has a role in the modulation of anxiety-like behavior in rats, showing regional differences; rostral regions have an anxiogenic role, while medial and caudal regions have an anxiolytic role, with a transition area around bregma +0.5. The present study suggests that the insula has a direct role in anxiety.

NDM-1 carbapenemase in Acinetobacter baumannii sequence type 32 in Ecuador

Objectives

To describe a clinical case of Acinetobacter baumannii sequence type (ST) 32 harbouring a New Delhi metallo-β-lactamase (NDM) in Ecuador.

Methods

We used multilocus sequence typing (MLST) to confirm the bacterial species and the sequence type of an A. baumannii isolate. We used synergy with the imipenem–EDTA disc method and the carbapenem inactivation method (CIM) to determine carbapenemase production; the presence of a carbapenemase gene was confirmed by PCR amplification and amplicon sequencing.

Results

Molecular characterization revealed the presence of A. baumannii ST32 harbouring the bla_NDM-1 gene in Ecuador. The bla_NDM-1 gene was isolated through PCR and amplified from a purified plasmid.

Conclusions

To the best of our knowledge, this is the first report of A. baumannii ST32 harbouring the bla_NDM-1 gene.

Role of TGFβ signaling in the pathogenesis of Alzheimer's disease

Aging is the main risk factor for Alzheimer’s disease (AD); being associated with conspicuous changes on microglia activation. Aged microglia exhibit an increased expression of cytokines, exacerbated reactivity to various stimuli, oxidative stress, and reduced phagocytosis of β-amyloid (Aβ). Whereas normal inflammation is protective, it becomes dysregulated in the presence of a persistent stimulus, or in the context of an inflammatory environment, as observed in aging. Thus, neuroinflammation can be a self-perpetuating deleterious response, becoming a source of additional injury to host cells in neurodegenerative diseases. In aged individuals, although transforming growth factor β (TGFβ) is upregulated, its canonical Smad3 signaling is greatly reduced and neuroinflammation persists. This age-related Smad3 impairment reduces protective activation while facilitating cytotoxic activation of microglia through several cellular mechanisms, potentiating microglia-mediated neurodegeneration. Here, we critically discuss the role of TGFβ-Smad signaling on the cytotoxic activation of microglia and its relevance in the pathogenesis of AD. Other protective functions, such as phagocytosis, although observed in aged animals, are not further induced by inflammatory stimuli and TGFβ1. Analysis in silico revealed that increased expression of receptor scavenger receptor (SR)-A, involved in Aβ uptake and cell activation, by microglia exposed to TGFβ, through a Smad3-dependent mechanism could be mediated by transcriptional co-factors Smad2/3 over the MSR1 gene. We discuss that changes of TGFβ-mediated regulation could at least partially mediate age-associated microglia changes, and, together with other changes on inflammatory response, could result in the reduction of protective activation and the potentiation of cytotoxicity of microglia, resulting in the promotion of neurodegenerative diseases.

Role of scavenger receptors in glia-mediated neuroinflammatory response associated with Alzheimer's disease

It is widely accepted that cells serving immune functions in the brain, namely, microglia and astrocytes, are important mediators of pathological phenomena observed in Alzheimer's disease. However, it is unknown how these cells initiate the response that results in cognitive impairment and neuronal degeneration. Here, we review the participation of the immune response mediated by glial cells in Alzheimer's disease and the role played by scavenger receptors in the development of this pathology, focusing on the relevance of class A scavenger receptor (SR-A) for A β clearance and inflammatory activation of glial cell, and as a potential target for Alzheimer's disease therapy.

[The bone bank of the University Clinic in Navarra]

The Bone bank at the University Clinic is described along with its three units: Electrical freezer (-40 degrees). Liquid nitrogen freezer (-197 degrees). Temperature programmer descend. The first unit is used for the preservation of cancellous bone, for a limited lapse of time; the second unit is employed for preserving cortical grafts for an unlimited period. The third unit allows to control the temperature descend rate, in order to preserve the viability of chondrocytes in grafts including epiphyseal ends. Clinical applications of bone grafts are currently enlarging in areas such as tumour surgery, spine surgery and arthrodesis and reconstructive procedures of the hip joint.