Obesity and the cerebral cortex: Underlying neurobiology in mice and humans

Obesity is a major modifiable risk factor for Alzheimer's disease (AD), characterized by progressive atrophy of the cerebral cortex. The neurobiology of obesity contributions to AD is poorly understood. Here we show with in vivo MRI that diet-induced obesity decreases cortical volume in mice, and that higher body adiposity associates with lower cortical volume in humans. Single-nuclei transcriptomics of the mouse cortex reveals that dietary obesity promotes an array of neuron-adverse transcriptional dysregulations, which are mediated by an interplay of excitatory neurons and glial cells, and which involve microglial activation and lowered neuronal capacity for neuritogenesis and maintenance of membrane potential. The transcriptional dysregulations of microglia, more than of other cell types, are like those in AD, as assessed with single-nuclei cortical transcriptomics in a mouse model of AD and two sets of human donors with the disease. Serial two-photon tomography of microglia demonstrates microgliosis throughout the mouse cortex. The spatial pattern of adiposity-cortical volume associations in human cohorts interrogated together with in silico bulk and single-nucleus transcriptomic data from the human cortex implicated microglia (along with other glial cells and subtypes of excitatory neurons), and it correlated positively with the spatial profile of cortical atrophy in patients with mild cognitive impairment and AD. Thus, multi-cell neuron-adverse dysregulations likely contribute to the loss of cortical tissue in obesity. The dysregulations of microglia may be pivotal to the obesity-related risk of AD.

Unveiling the antinociceptive mechanisms of Methyl-2-(4-chloro-phenyl)-5-benzoxazoleacetate: insights from nociceptive assays in mice

OBJECTIVE

Methyl-2-(4-chloro- phenyl)-5-benzoxazoleacetate (MCBA), a synthetic benzoxazole derivative with established antipsoriatic efficacy, was investigated for potential antinociceptive effects. This study employs various nociceptive assays in mice to elucidate MCBA's antinociceptive mechanisms.

MATERIALS AND METHODS

MCBA's antinociceptive potential was tested against various nociception models induced by formalin, glutamate, capsaicin, a transient receptor potential vanilloid 1 (TRPV1) receptor agonist, and phorbol 12-myristate 13-acetate, a protein kinase C (PKC) activator. It was then assessed using the hot plate test and examined within the acetic acid-induced writhing test. During the acetic acid-induced writhing test, MCBA was pre-challenged against selective receptor antagonists such as naloxone, caffeine, atropine, yohimbine, ondansetron, and haloperidol. It was also pre-challenged with ATP-sensitive potassium channel inhibitor (glibenclamide) to further elucidate its antinociceptive mechanism.

RESULTS

The results showed that oral administration of MCBA led to a dose-dependent and significant inhibition (p < 0.05) of nociceptive effects across all evaluated models at doses of 60, 120, and 240 mg/kg. Moreover, the efficacy of MCBA's antinociceptive potential was significantly counteracted (p < 0.0001) by specific antagonists: (i) directed at adenosinergic, alpha-2 adrenergic, and cholinergic receptors using caffeine, yohimbine, and atropine, respectively; and (ii) targeting ATP-sensitive potassium channels, employing glibenclamide. Antagonists aimed at opioidergic and serotoninergic receptors (naloxone and ondansetron, respectively) had poor utility in inhibiting antinociceptive activity. Conversely, the dopaminergic receptor antagonist haloperidol potentiated locomotor abnormalities associated with MCBA treatment.

CONCLUSIONS

MCBA-induced antinociception involves modulation of glutamatergic-, TRVP1 receptors- and PKC-signaling pathways. It impacts adenosinergic, alpha-2 adrenergic, and cholinergic receptors and opens ATP-sensitive potassium channels.

Failure of human rhombic lip differentiation underlies medulloblastoma formation

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain^1-4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage^5-8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL^9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage^3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES⁺KI67⁺ unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB.

Behavioral evidence for two distinct memory systems in rats

Serial reaction time tasks, in which subjects have to match a target to a cue, are used to explore whether non-human animals have multiple memory systems. Predictable sub-sequences embedded in the sequence of cues are responded to faster, demonstrating incidental learning, often considered implicit. Here, we used the serial implicit learning task (SILT) to determine whether rats' memory shows similar effects. In SILT, subjects must nose-poke into a sequence of two lit apertures, S1 and S2. Some S1 are always followed by the same S2, creating predictable sequences (PS). Across groups, we varied the proportion of PS trials, from 10 to 80%, and show that rats with more PS experience do better on them than on unpredictable sequences, and better than rats with less experience. We then introduced test trials in which no S2 was cued. Rats with more PS experience did better on test trials. Finally, we reversed some sequences (from predictable to unpredictable and vice versa) and changed others. We find that rats with more PS experience perseverate on old (now incorrect) responses more than those with less PS experience. Overall, we find a discontinuity in performance as the proportion of PS increases, suggesting a switch in behavioral strategies or memory systems, which we confirm using a Process Dissociation Procedure analysis. Our data suggest that rats have at least two distinct memory systems, one of which appears to be analogous to human implicit memory and is differentially activated by varying the proportion of PS in our task.

School bullying int Tunisia: Psychological profile of harassers

Introduction

School Bullying is an educational and a health care issue that was kept hided for a long time. Despite, growing interest about this issue, it’s still a topic that is not well known and well analysed in Tunisia.

Objectives

- Evaluate the prevalence of school bullying among Middle school students - Establish the psychological profile of harassers

Methods

It’s a cross sectional study including 600 students of 2 middle schools of the region of Sousse -Tunisia during the month of March 2020. “The adolescent peer relations instrument” was used to identify school bullying and its type. The “Child Behaviour Checklist” questionnaire was used to identify emotional and behavioural problems among children. Self esteem levels were evaluated by the “Rosenberg Self Esteem Scale”.

Results

The mean age of participants was 13 years and 9 months ±1 year and 4 months. 95.1 % of the participants have experienced school harassment, but also 92% of them harassed their peers. Boys were more frequently bullies than girls (p<0.01). There was no significant difference in self esteem levels between bullies and non-bullies adolescents. Among the 8 syndroms explored by the Child behaviour checklist, adolescents experiencing one of the 7 folllowing items (Anxious syndrome, Depressive syndrome, Aggressive behaviour, Attention problems, Social problem, Thoughts problems and Withdrawal problems) had significantly higher risk of being a bully (p values between 0.001 and 0.02).

Conclusions

This study emphasizes the high prevalence of school bullying among adolescents in Tunisia. Most of the psychological problems explored in this study seem to be higher among bullies.

Spatiotemporal Mapping of Early Volume Loss in the Mouse Brain after Cranial Irradiation

Sequelae after pediatric cranial radiotherapy (CRT) result in long-term changes in brain structure. While past evidence indicates regional differences in brain volume change, it remains unclear how these manifest in the time course of change after CRT. In this study, we spatiotemporally characterized volume losses induced by cranial irradiation in a mouse model, with a dense sampling of measurements over the first week postirradiation. Wild-type mice received whole-brain irradiation (7 Gy) or sham irradiation (0 Gy) at 16 days of age. In vivo magnetic resonance imaging was performed at one time point before, and 2-4 time points postirradiation in each mouse, with a particular focus on sampling during the first week after cranial irradiation. Volume changes across the brain were measured, and the degree and timing of volume loss were quantified across structures from a predefined atlas. Volume measurements across the brain after cranial irradiation revealed a ∼2-day delay in which volume is not significantly altered, after which time volume change proceeds over the course of four days. Volume losses were 3% larger and emerged 40% slower in white matter than in gray matter. Large volume loss was also observed in the ventricles. Differences in the timing and magnitude of volume change between gray and white matter after cranial irradiation were observed. These results suggest differences in the mechanism and/or kinetics underlying the associated radio-response, which may have implications in development.

Discrepancies between parent and child report of anxiety in children with high functioning autism spectrum disorder

Introduction

Many children with autism spectrum disorder (ASD) experience high levels of anxiety. However, inconsistencies between parent and child reports may complicate the assessment of anxiety in this population.

Objectives

The aim of this study is to investigate discrepancies between parent and self-reported anxiety among children with high functioning ASD.

Methods

Children aged between 8 and16 years with high functioning ASD, followed in the outpatient unite of child psychiatry at the University Hospital of Monastir, Tunisia and their parents, were invited to complete the Arabic version of the Anxiety Scale for Children with Autism Spectrum Disorder (ASC-ASD). The ASC-ASD is a 24-item questionnaire with six sub-scales, designed specifically for the assessment of anxiety symptomatology in children with ASD. A total score of ≥ 20 indicate significant levels of anxiety.

Results

We recruited 66 children and their parents. The mean age was 10 years old. High rates of anxiety were found: children’s reports revealed that 70% of them present anxiety and 60 % were coated anxious by parent’s reports. Performance Anxiety, Uncertainty and Social Anxiety were the most frequent types of anxiety reported by both parents and children. We did not find a significant difference between the parents and children rating of anxiety except for the apprehension subscale.

Conclusions

This is one of the first studies to compare between parent and self-reported anxiety among children with ASD using an autism-specific measure of anxiety. No discrepancies have been found between parents and children report, however others studies are needed to investigate discrepancies in children with severe ASD.

The relationship between self-esteem and bullying behavior among adolescent in tunisia

Introduction

Bullying is a serious problem for school youth. It is prevalent across the elementary and secondary school years and it has serious consequences for both bullies and victims.

Objectives

The aim of this study was to investigate the relationship between self-esteem and bullying behavior.

Methods

We conducted a cross-sectional study including children enrolled in two high schools in Sousse, Tunisia. The students were asked to complete two questionnaires: the Adolescent Peer Relations Instrument witch is a multidimensional scale designed to assess bullying involvement both as target and perpetrator and the Rosenberg self-esteem scale.

Results

We recruited 600 adolescent. The mean age of our population was 13.76 ±1.37 and the sex ratio was 1. More than 95% of adolescent who reported that they had been victims of bullying had a very low self-esteem comparing to those who stated that they had never been bullied (4.4%). Our results have also shown that bullies had a lower self-esteem than children who had not bullied others.

Conclusions

We found that both victims and bullies tend to have low self-esteem. Our findings could help to understand better the role that individual characteristics and personal qualities such as self-esteem play on bullying, and provide the scientific knowledge to develop successful strategies to prevent this phenomenon.

When healing becomes a burden: The feedback of tunisian psychiatrists

Introduction

Psychiatry is a fascinating medical specialty. Many reasons may motivate early career doctors to choose this field. However, this experience could have a different impact on their quality of life and social functioning.

Objectives

we aimed to assess the impact of psychiatry as a medical career, on the psychiatrist’s quality of life, and to evaluate their feedback on their experience and how it effects their life.

Methods

This is a cross-sectional descriptive study of 68 psychiatrists. An E-questionnaire has been sent via a psychiatrist’s closed groups on social media. We collected sociodemographic data, we also used the stress perceived scale, and we explored the quality of life using the SF-12 questionnaire.

Results

The participants were mostly females with a mean age of 32 years (range25-65). Only 10% of psychiatrists had psychiatric history mostly depression. Concerning substance use, 15% were smokers, 17% used alcohol, 10% smoked occasionally cannabis and 23 % used different psychotropic drugs. 73% our sample were interested in psychiatry during their studies. 60% of our population considered the role of psychiatrists ambiguous among other colleagues. A very high perceived stress was noted in 90 % of our sample. Physical health status was in the average of standard deviation wether mental health status was below average among psychiatrists. The most frustrating situation mentioned was the absence of intermediate structures to receive psychotic patients.

Conclusions

Tunisians psychiatrists are facing many obstacles during the practice of their job, that would transform their passion into demotivation and a desire to leave the country.

Measuring bullying victimization through a closed ended question and a validated measure in a population of tunisian adolescents: What difference does it make?

Introduction

School bullying is a serious problem among tunisian children and adolesent. In our every day practice, we see a considerable number of suicide attempts among bullying victims. Our study tries to provide more information on this phenomenon, in order to organize efficient preventtion measures.

Objectives

Measuring the prevalence of bullying victimization in the town of Sousse-Tunisia Comparing the prevalence found through a validated measurement tool and a closed end question

Methods

It is a cross-sectional study among a sample of 1127 adolescents, aged 12 to 17 years old. The adolescents were divided in two groups the first group, composed of 527 adolescents, answered a closed end (yes/no) question “Have you been a victim of Bullying”; the second group, composed of 600 adolescents, responded to the “adolescent peer relation instrument”.

Results

The first group was composed of 48% of boys and 52% of girls with a mean age of 13,24 ± 0,96. The second group was composed of 50% of boys and 50% of girls with a mean age of 13.76 ±1.37. We found a bullying victimization prevalence of 11% for the first group versus 95.1% for the second group. For both groups we didn’t find a significant difference in the prevalence of bullying victimization according to sociodemographic factors except the higher family income that was associates to less bullying victimisation for the first group (p=0,04)

Conclusions

The high prevalence of bullying victimization we found using a validated measurement is alarming in terms of the urgency of interventions to prevent bullying in schools.

Comparison of the single dose pharmacokinetics, pharmacodynamics, and safety of two novel oral formulations of dimethandrolone undecanoate (DMAU): a potential oral, male contraceptive

Dimethandrolone (DMA, 7α,11β-dimethyl-19-nortestosterone) has both androgenic and progestational activities, ideal properties for a male hormonal contraceptive. In vivo, dimethandrolone undecanoate (DMAU) is hydrolyzed to DMA. We showed previously that single oral doses of DMAU powder in capsule taken with food are well tolerated and effective at suppressing both LH and testosterone (T), but absorption was low. We compared the pharmacokinetics and pharmacodynamics of two new formulations of DMAU, in castor oil and in self-emulsifying drug delivery systems (SEDDS), with the previously tested powder formulation. DMAU was dosed orally in healthy adult male volunteers at two academic medical centers. For each formulation tested in this double-blind, placebo-controlled study, 10 men received single, escalating, oral doses of DMAU (100, 200, and 400 mg) and two subjects received placebo. All doses were evaluated for both fasting and with a high fat meal. All three formulations were well tolerated without clinically significant changes in vital signs, blood counts, or serum chemistries. For all formulations, DMA and DMAU showed higher maximum (p < 0.007) and average concentrations (p < 0.002) at the 400 mg dose, compared with the 200 mg dose. The powder formulation resulted in a lower conversion of DMAU to DMA (p = 0.027) compared with both castor oil and SEDDS formulations. DMAU in SEDDS given fasting resulted in higher serum DMA and DMAU concentrations compared to the other two formulations. Serum LH and sex hormone concentrations were suppressed by all formulations of 200 and 400 mg DMAU when administered with food, but only the SEDDS formulation was effectively suppressed serum T when given fasting. We conclude that while all three formulations of oral DMAU are effective and well tolerated when administered with food, DMAU in oil and SEDDS increased conversion to DMA, and SEDDS may have some effectiveness when given fasting. These properties might be advantageous for the application of DMAU as a male contraceptive.

Endotracheal and aerosol administrations of ceftazidime in patients with nosocomial pneumonia: pharmacokinetics and absolute bioavailability

Pharmacokinetic studies on ceftazidime, an aminothiazole cephalosporin with a wide spectrum of antibacterial activity, including activity against Pseudomonas aeruginosa, were performed in patients with nosocomial pneumonia. The concentration-time profiles of ceftazidime in plasma, urine, and bronchial secretions of 12 patients were investigated after intravenous (i.v.) (n = 12), endotracheal (n = 10), and aerosol (n = 5) administrations. In all cases a 1-g dose was administered. Concentrations of drug in all samples were assayed by high-performance liquid chromatography with UV detection. The elimination of the drug from the blood followed a biexponential (i.v. administration) or a monoexponential (endotracheal and aerosol administrations) decay, with an elimination half-life of 6 h and a total body clearance of 4.2 liters/h. The apparent volume of distribution was 0.36 liter/kg of body weight. Renal clearance of the drug accounted for 58% of the total clearance; 66% +/- 17.7%, 33.5% +/- 17.3%, and 6.59% +/- 3.45% of the administered dose were eliminated in urine as parent drug after i.v., endotracheal, and aerosol administrations, respectively. The absolute bioavailabilities were 0.47 and 0.08 for endotracheal and aerosol administrations, respectively. Very high concentrations were found in bronchial secretions after local administration. The MICs for 90% of the most important pathogens responsible for nosocomial infections were exceeded by concentrations in bronchial secretion for up to 12 h after i.v. infusion and for up to 24 h after endotracheal and aerosol administrations.