Dynamic local mRNA localization and translation occurs during the postnatal molecular maturation of perivascular astrocytic processes

Astrocytes are highly ramified and send out perivascular processes (PvAPs) that entirely sheathe the brain's blood vessels. PvAPs are equipped with an enriched molecular repertoire that sustains astrocytic regulatory functions at the vascular interface. In the mouse, PvAP development starts after birth and is essentially complete by postnatal day (P) 15. Progressive molecular maturation also occurs over this period, with the acquisition of proteins enriched in PvAPs. The mechanisms controlling the development and molecular maturation of PvAPs have not been extensively characterized. We reported previously that mRNAs are distributed unequally in mature PvAPs and are locally translated. Since dynamic mRNA localization and local translation influence the cell's polarity, we hypothesized that they might sustain the postnatal maturation of PvAPs. Here, we used a combination of molecular biology and imaging approaches to demonstrate that the development of PvAPs is accompanied by the transport of mRNA and polysomal mRNA into PvAPs, the development of a rough endoplasmic reticulum (RER) network and Golgi cisternae, and local translation. By focusing on genes and proteins that are selectively or specifically expressed in astrocytes, we characterized the developmental profile of mRNAs, polysomal mRNAs and proteins in PvAPs from P5 to P60. We found that some polysomal mRNAs polarized progressively towards the PvAPs. Lastly, we found that expression and localization of mRNAs in developing PvAPs is perturbed in a mouse model of megalencephalic leukoencephalopathy with subcortical cysts. Our results indicate that dynamic mRNA localization and local translation influence the postnatal maturation of PvAPs.

Challenging the Role of Subtotal Resection Following Proton Radiotherapy for Adenoid Cystic Carcinoma of the Head and Neck

PURPOSE/OBJECTIVE(S)

To report long-term outcomes of patients with adenoid cystic carcinoma (ACC) of the head and neck treated with proton radiotherapy.

MATERIALS/METHODS

On this IRB-approved, single institutional prospective outcomes registry, 56 patients were included with de novo, nonmetastatic adenoid carcinoma of the head and neck treated with primary (n = 9) or adjuvant proton therapy from June 2007 to December 2021. The cohort had 30 women and 26 men with a median age of 57 years (range, 10-81 years). Twenty-nine percent (n = 16) had intracranial extension, 23% (n = 13) had orbital extension, and 55% (n = 31) had clinical cranial nerve involvement at the time of radiotherapy. Thirty patients underwent gross total resection (GTR), 26 had gross disease at the time of treatment undergoing a subtotal resection (STR) (n = 17) or biopsy alone (n = 9). The median dose to the primary site was 72.6 GyRBE (range, 64-74.4 GyRBE) delivered in either once (n = 19) or twice (n = 37) daily treatments. Thirty patients received either elective nodal irradiation (ENI) in a node negative neck or concurrent chemotherapy.

RESULTS

With a median follow-up of 6.2 years (range, 0.9 - 14.7 years), the 5-year local-regional control (LRC), disease free survival (DFS), cause-specific survival (CCS) and overall survival (OS) were 88%, 85%, 89%, and 89%, respectively. Cranial extension (p = 0.003) and gross residual tumor (p = 0.0388) were factors associated with decreased LRC. While LRC for those with a GTR was 96%, those with STR or biopsy alone were 81% and 76%, respectively. T-stage (p = 0.0154), cranial extension (p = 0.0056), extent of resection (p = 0.0355), and gross residual tumor (p = 0.0094) were associated with decreased DFS. T-stage (p = 0.0099), extent of surgery (p = 0.029) and gross residual tumor (p.0071) were associated with decreased CCS. The 5-year cumulative incidence of clinically significant late grade ³3 toxicity was 15% and the crude incidence at most recent follow-up was 23% (n = 13). There was no LRC benefit with ENI (p = 0.94).

CONCLUSION

Proton therapy provides excellent disease control for head and neck ACC with acceptable toxicity. Gross residual disease at the time of treatment and intracranial involvement were significant prognostic features for worse outcomes. STR did not confer benefit over biopsy only at 5-years and may question the role of extensive and morbid operations if GTR is not technically feasible.

Microglia produce the amyloidogenic ABri peptide in familial British dementia

Mutations in ITM2B cause familial British, Danish, Chinese and Korean dementias. In familial British dementia (FBD) a mutation in the stop codon of the ITM2B gene (also known as BRI2 ) causes a C-terminal cleavage fragment of the ITM2B/BRI2 protein to be extended by 11 amino acids. This fragment, termed amyloid-Bri (ABri), is highly insoluble and forms extracellular plaques in the brain. ABri plaques are accompanied by tau pathology, neuronal cell death and progressive dementia, with striking parallels to the aetiology and pathogenesis of Alzheimer's disease. The molecular mechanisms underpinning FBD are ill-defined. Using patient-derived induced pluripotent stem cells, we show that expression of ITM2B/BRI2 is 34-fold higher in microglia than neurons, and 15-fold higher in microglia compared with astrocytes. This cell-specific enrichment is supported by expression data from both mouse and human brain tissue. ITM2B/BRI2 protein levels are higher in iPSC-microglia compared with neurons and astrocytes. Consequently, the ABri peptide was detected in patient iPSC-derived microglial lysates and conditioned media but was undetectable in patient-derived neurons and control microglia. Pathological examination of post-mortem tissue support ABri expression in microglia that are in proximity to pre-amyloid deposits. Finally, gene co-expression analysis supports a role for ITM2B/BRI2 in disease-associated microglial responses. These data demonstrate that microglia are the major contributors to the production of amyloid forming peptides in FBD, potentially acting as instigators of neurodegeneration. Additionally, these data also suggest ITM2B/BRI2 may be part of a microglial response to disease, motivating further investigations of its role in microglial activation. This has implications for our understanding of the role of microglia and the innate immune response in the pathogenesis of FBD and other neurodegenerative dementias including Alzheimer's disease.

[Predictors of student anxiety during the pandemic (COVID-19)]

INTRODUCTION

The coronavirus disease (COVID-19) pandemic has caused a major health crisis and the quarantine of most of the planet's population. During confinement, anxiety symptoms may appear. The pandemic dramatically changes the lives of individuals by becoming a concrete manifestation of the threat. Constant exposure to information about the virus can increase anxiety, especially since the information may be erroneous or contradictory. This article examines the factors that predict student anxiety in the context of a pandemic.

METHOD

The quantitative study involves a sample of 445 students from the University of Quebec in Abitibi-Témiscamingue. Anxiety was measured using the Beck Anxiety Inventory, and several sociodemographic variables were tested.

RESULTS

The results demonstrated the effects of certain variables on anxiety, especially for women and non-binary people, were more marked than for men. Having dependent children has proven to be a protective factor.

CONCLUSION

The study suggests that this variability is now considered when proposing intervention measures in a containment context. The limitations and perspectives of the study are presented and analyzed.

Neuronal tau species transfer to astrocytes and induce their loss according to tau aggregation state

Deposits of different abnormal forms of tau in neurons and astrocytes represent key anatomo-pathological features of tauopathies. Although tau protein is highly enriched in neurons and poorly expressed by astrocytes, the origin of astrocytic tau is still elusive. Here, we used innovative gene transfer tools to model tauopathies in adult mouse brains and to investigate the origin of astrocytic tau. We showed in our adeno-associated virus (AAV)-based models and in Thy-Tau22 transgenic mice that astrocytic tau pathology can emerge secondarily to neuronal pathology. By designing an in vivo reporter system, we further demonstrated bidirectional exchanges of tau species between neurons and astrocytes. We then determined the consequences of tau accumulation in astrocytes on their survival in models displaying various status of tau aggregation. Using stereological counting of astrocytes, we report that, as for neurons, soluble tau species are highly toxic to some subpopulations of astrocytes in the hippocampus, whereas the accumulation of tau aggregates does not affect their survival. Thus, astrocytes are not mere bystanders of neuronal pathology. Our results strongly suggest that tau pathology in astrocytes may significantly contribute to clinical symptoms.

Imidazoacridinones arrest cell-cycle progression in the G2 phase of L1210 cells

Imidazoacridinones are a new class of highly potent antineoplastic agents synthesised at the Technical University of Gdansk. The pharmacophoric alkyldiamine group, which is also present in anthracenediones (e.g. ametantrone, mitoxantrone), has been shown to be responsible for their antineoplastic activity. In view of their chemical similarity to anthracenediones, we anticipated that the imidazoacridinones would have a mechanism of action similar to that of these agents and that this would be reflected by a similar influence on cell-cycle progression. Flow cytometry was used to monitor the effect of three derivatives of imidazoacridinone (C-1263, C-1310 and C-1311) on L1210 cell cycle traverse at concentrations ranging from 0.01 to 0.9 microgram/ml, corresponding to their 50% and 90% effective concentrations (EC50 and EC90 values), over times of drug treatment ranging from 1 to 48 h. The results demonstrate that all of the compounds produced a similar effect, inducing preferential and complete arrest (accumulation) of cells in the G2 phase of the cell cycle (i.e. G2 block). The kinetics of the induction of G2 arrest were dependent on both the dose and the duration of treatment. Cell-cycle arrest was reversible for up to about 3 h of treatment, being quite irreversible at longer incubation times. Microscopic inspection of cells performed in parallel with flow cytometry confirmed that imidazoacridinones induced a G2, not a G2/M, block.

QSAR of acridines, III. Structure-activity relationship for antitumour imidazoacridinones and intercorrelations between in vivo and in vitro tests

A study on quantitative relationships between the biological activity and physicochemical properties of antitumour 5-alkylaminoimidazoacridinone derivatives was carried out. The activity was based on the results of several in vitro tests as well as experimental antileukaemic therapy. The capacity factor, log k', determined by the reverse-phase HPLC method, was a measure of lipophilic properties. UV and NMR spectra of the compounds were employed to describe electronic parameters. Values of steric descriptors were calculated as topological indexes. Results obtained by means of principal component analysis (PCA) allow us to group biological tests into two subsets: the lipophilicity-dependent and lipophilicity-independent test groups. The highest intercorrelation, R = 0.92, was shown between the optimal dose, pOD, determined in leukaemia P388-bearing mice and cytotoxicity expressed as pEC50 in leukaemia cells. The equation describing this relationship could be applied to predict the therapeutic doses of imidazoacridinone derivatives which would be effective in experimental antileukaemic therapy. The quantitative structure-activity relationship (QSAR) study showed that lipophilic properties significantly influence cytotoxicity, pEC50, and antileukaemic potency, pOD, only in the case of 8-hydroxy analogues of imidazoacridinones, whereas the activity of the remaining derivatives is very low and does not depend on lipophilicity. Electronic resonance properties seem to influence this specific impact of lipophilicity on the biological activity of 8-hydroxy derivatives. Hence, it may be possible to improve the antitumour activity of 8-hydroxyimidazoacridinones by obtaining more hydrophilic derivatives, up to the optimal value of the lipophilic parameter.

Arylesterase in serum: elaboration and clinical application of a fixed-incubation method

A sensitive, specific, and simple method for determining serum or urine arylesterase (EC 3.1.1.2) is described. The enzyme acts on phenyl acetate to release phenol, which produces a stable indophenol dye with 4-aminoantipyrine and potassium ferricyanide. Arylesterase, a thiol enzyme, is reactivated by 2-mercaptoethanol and by cysteine, but not by reduced glutathione. Calcium is indispensable to stabilize and to activate (Km = 0.85 mmol/L) the enzyme; complete protection is achieved at CaCl2 20 mmol/L. Magnesium acts as a weak (Ki = 116 mmol/L), lanthanum as a potent (Ki = 5 mumol/L) competitive inhibitor. The activity is measured in diluted sera at phenyl acetate 4.0 mmol/L (Km = 1.12 mmol/L), pH 7.8 and 25 degrees C. The normal range extends from 53 to 186 kU/L, and four isoenzymes are present in sera from healthy adults. Arylesterase decreases in hepatic disorders, especially in cirrhosis and carcinoma of the liver, with reduction of the penultimate fraction in polyacryalmide gel electrophoresis.

Arylesterase in serum: elaboration and clinical application of a fixed-incubation method

A sensitive, specific, and simple method for determining serum or urine arylesterase (EC 3.1.1.2) is described. The enzyme acts on phenyl acetate to release phenol, which produces a stable indophenol dye with 4-aminoantipyrine and potassium ferricyanide. Arylesterase, a thiol enzyme, is reactivated by 2-mercaptoethanol and by cysteine, but not by reduced glutathione. Calcium is indispensable to stabilize and to activate (Km = 0.85 mmol/L) the enzyme; complete protection is achieved at CaCl2 20 mmol/L. Magnesium acts as a weak (Ki = 116 mmol/L), lanthanum as a potent (Ki = 5 mumol/L) competitive inhibitor. The activity is measured in diluted sera at phenyl acetate 4.0 mmol/L (Km = 1.12 mmol/L), pH 7.8 and 25 degrees C. The normal range extends from 53 to 186 kU/L, and four isoenzymes are present in sera from healthy adults. Arylesterase decreases in hepatic disorders, especially in cirrhosis and carcinoma of the liver, with reduction of the penultimate fraction in polyacryalmide gel electrophoresis.