Predominant cardiac sympathetic modulation during wake and sleep in patients with Rett syndrome.

BACKGROUND: Rett syndrome (RTT) is a rare neurological disorder primarily associated with mutations in the methyl-CpG-binding protein 2 (MECP2) gene. The syndrome is characterized by cognitive, social, and physical impairments, as well as sleep disorders and epilepsy. Notably, dysfunction of the autonomic nervous system is a key feature of the syndrome. Although Heart Rate Variability (HRV) has been used to investigate autonomic nervous system dysfunction in RTT during wakefulness, there is still a significant lack of information regarding the same during sleep. Therefore, our aim was to investigate cardiovascular autonomic modulation during sleep in subjects with RTT compared to an age-matched healthy control group (HC). METHOD: A complete overnight polysomnographic (PSG) recording was obtained from 11 patients with Rett syndrome (all females, 10 ± 4 years old) and 11 HC (all females, 11 ± 4 years old; p = 0.48). Electrocardiogram and breathing data were extracted from PSG and divided into wake, non-REM, and REM sleep stages. Cardiac autonomic control was assessed using symbolic non-linear heart rate variability analysis. The symbolic analysis identified three patterns: 0 V% (sympathetic), 2UV%, and 2LV% (vagal). RESULTS: The 0 V% was higher in the RTT group than in the HC group during wake, non-REM, and REM stages (p < 0.01), while the 2LV and 2UV% were lower during wake and sleep stages (p < 0.01). However, the 0 V% increased similarly from the wake to the REM stage in both RTT and HC groups. CONCLUSIONS: Therefore, the sympatho-vagal balance shifted towards sympathetic predominance and vagal withdrawal during wake and sleep in RTT, although cardiac autonomic dynamics were preserved during sleep.

Berberine and hesperidin prevent the memory consolidation impairment induced by pentylenetetrazole in zebrafish.

This study verified the effects of the natural compounds berberine and hesperidin on seizure development and cognitive impairment triggered by pentylenetetrazole (PTZ) in zebrafish. Adult animals were submitted to a training session in the inhibitory avoidance test and, after 10 minutes, they received an intraperitoneal injection of 25, 50, or 100 mg/kg berberine or 100 or 200 mg/kg hesperidin. After 30 minutes, the animals were exposed to 7.5 mM PTZ for 10 minutes. Animals were submitted to the test session 24 h after the training session to verify their cognitive performance. Zebrafish larvae were exposed to 100 µM or 500 µM berberine or 10 µM or 50 µM hesperidin for 30 minutes. After, larvae were exposed to PTZ and had the seizure development evaluated by latency to reach the seizure stages I, II, and III. Adult zebrafish pretreated with 50 mg/kg berberine showed a longer latency to reach stage III. Zebrafish larvae pretreated with 500 µM berberine showed a longer latency to reach stages II and III. Hesperidin did not show any effect on seizure development both in larvae and adult zebrafish. Berberine and hesperidin pretreatments prevented the memory consolidation impairment provoked by PTZ-induced seizures. There were no changes in the distance traveled in adult zebrafish pretreated with berberine or hesperidin. In larval stage, berberine caused no changes in the distance traveled; however, hesperidin increased the locomotion. Our results reinforce the need for investigating new therapeutic alternatives for epilepsy and its comorbidities.

Removal of doxorubicin hydrochloride and crystal violet from aqueous solutions using spray-dried niobium oxide coated with chitosan-activated carbon: Experimental and DFT calculations.

Spray-dried niobium oxide coated with chitosan-activated carbon (NIC) was synthesized and used to remove doxorubicin hydrochloride and crystal violet from aqueous solutions under different parameters such as solution pH (2, 4, 6, and 8), contact time (1 to 9 h), initial concentration (20 to 200 mg L-1), and competing ions (0.1 M of CaCl2 and NaCl). The addition of 5 % chitosan-activated carbon to the matrix of niobium oxide slightly increased the specific surface area from 26 to 30 m2 g-1, with the introduction of a carboxylic functional group. This led to an increase in the amount of adsorbed doxorubicin hydrochloride (DOH) from 30 to 44 mg g-1 and that of crystal violet (CV) from 15 to 32 mg g-1 from the initial respective 100 mg L-1 at pH 8. The data from the concentration study fitted into Liu isotherm having adsorption capacity of 128 and 57 mg g-1 for DOH and CV respectively, while pseudo first and second order are more suitable for adsorption kinetics. The additional functional groups on the IR spectrum of NIC after the adsorption of DOH and CV confirmed the interaction between NIC and the adsorbates' molecules. The mechanism of adsorption was supported by DFT calculations.

All-fiber broadband spectral acousto-optic modulation of a tubular-lattice hollow-core optical fiber.

We demonstrate a broadband acousto-optic notch filter based on a tubular-lattice hollow-core fiber for the first time to our knowledge. The guided optical modes are modulated by acoustically induced dynamic long-period gratings along the fiber. The device is fabricated employing a short interaction length (7.7 cm) and low drive voltages (10 V). Modulated spectral bands with 20 nm half-width and maximum depths greater than 60% are achieved. The resonant notch wavelength is tuned from 743 to 1355 nm (612 nm span) by changing the frequency of the electrical signal. The results indicate a broader tuning range compared to previous studies using standard and hollow-core fibers. It further reveals unique properties for reconfigurable spectral filters and fiber lasers, pointing to the fast switching and highly efficient modulation of all-fiber photonic devices.

How do microplastics alter molluscicidal activity? Effects of weathered microplastics and niclosamide in developing freshwater snails.

Despite the wide distribution and persistence of microplastics (MPs), their interactive effects with molluscicides are unknown. Schistosomiasis, a neglected tropical disease, affects 236.6 million people worldwide. Niclosamide (NCL) is the only molluscicide recommended by the World Health Organization (WHO) and it is used to control the population of Schistosoma spp.'s intermediate host. Thus, this study aimed to evaluate of the interaction between polyethylene (PE) MPs and NCL, and their associated toxicity in the freshwater snail Biomphalaria glabrata (Say 1818). Weathered PE MPs were characterized and theoretical analysis of NCL-MP adsorption nature was made using quantum mechanical calculations. The toxicity of NCL isolated (0.0265 to 0.0809 mg L-1) and under interaction with PE MPs (3400 µg L-1) in B. glabrata embryos and newly hatched snails was analyzed. In silico analysis confirmed the adsorption mechanisms of NCL into PE MPs. PE MPs decreased the NCL toxicity to both B. glabrata developmental stages, increasing their survival and NCL lethal concentrations, indicating concerns regarding NCL use as molluscicide in aquatic environments polluted by MPs. In conclusion, MPs may change the efficiency of chemicals used in snail control programs.

Pathogenic CANVAS (AAGGG)n repeats stall DNA replication due to the formation of alternative DNA structures.

CANVAS is a recently characterized repeat expansion disease, most commonly caused by homozygous expansions of an intronic (A2G3)n repeat in the RFC1 gene. There are a multitude of repeat motifs found in the human population at this locus, some of which are pathogenic and others benign. In this study, we conducted structure-functional analyses of the pathogenic (A2G3)n and nonpathogenic (A4G)n repeats. We found that the pathogenic, but not the nonpathogenic, repeat presents a potent, orientation-dependent impediment to DNA polymerization in vitro. The pattern of the polymerization blockage is consistent with triplex or quadruplex formation in the presence of magnesium or potassium ions, respectively. Chemical probing of both repeats in vitro reveals triplex H-DNA formation by only the pathogenic repeat. Consistently, bioinformatic analysis of S1-END-seq data from human cell lines shows preferential H-DNA formation genome-wide by (A2G3)n motifs over (A4G)n motifs. Finally, the pathogenic, but not the nonpathogenic, repeat stalls replication fork progression in yeast and human cells. We hypothesize that the CANVAS-causing (A2G3)n repeat represents a challenge to genome stability by folding into alternative DNA structures that stall DNA replication.

Cholecalciferol Exhibits no Antibacterial Effect on Staphylococcus aureus and Escherichia coli: an in-vitro Study.

BACKGROUND: The pleiotropic effect of cholecalciferol (vitamin D3) has gained significant momentum and has been explored widely. OBJECTIVES: The study aimed to investigate the antimicrobial effect of cholecalciferol against S. aureus and E. coli. METHODS: An in-vitro study was performed for the antimicrobial effect of cholecalciferol against S. aureus and E. coli. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined following the broth microdilution method. RESULTS: The MIC value of cholecalciferol against both S. aureus and E. coli was 0.312 mg/ml, and the MBC for both organisms was 1.25 mg/ml. However, we also observed a significant antimicrobial effect in the dimethyl sulfoxide (DMSO) control at 12.5% (v/v). Therefore, the observed antimicrobial effect may be attributed to DMSO, indicating cholecalciferol does not directly inhibit S. aureus and E. coli. CONCLUSION: This study indicates that cholecalciferol does not directly inhibit S. aureus and E. coli. Hence, we suggest exploring the antibacterial properties of other vitamin D analogs, such as calcitriol or its synergetic effect with other antimicrobial agents.

Operando probing of the surface chemistry during the Haber-Bosch process.

The large-scale conversion of N2 and H2 into NH3 (refs. 1,2) over Fe and Ru catalysts3 for fertilizer production occurs through the Haber-Bosch process, which has been considered the most important scientific invention of the twentieth century4. The active component of the catalyst enabling the conversion was variously considered to be the oxide5, nitride2, metallic phase or surface nitride6, and the rate-limiting step has been associated with N2 dissociation7-9, reaction of the adsorbed nitrogen10 and also NH3 desorption11. This range of views reflects that the Haber-Bosch process operates at high temperatures and pressures, whereas surface-sensitive techniques that might differentiate between different mechanistic proposals require vacuum conditions. Mechanistic studies have accordingly long been limited to theoretical calculations12. Here we use X-ray photoelectron spectroscopy-capable of revealing the chemical state of catalytic surfaces and recently adapted to operando investigations13 of methanol14 and Fischer-Tropsch synthesis15-to determine the surface composition of Fe and Ru catalysts during NH3 production at pressures up to 1 bar and temperatures as high as 723 K. We find that, although flat and stepped Fe surfaces and Ru single-crystal surfaces all remain metallic, the latter are almost adsorbate free, whereas Fe catalysts retain a small amount of adsorbed N and develop at lower temperatures high amine (NHx) coverages on the stepped surfaces. These observations indicate that the rate-limiting step on Ru is always N2 dissociation. On Fe catalysts, by contrast and as predicted by theory16, hydrogenation of adsorbed N atoms is less efficient to the extent that the rate-limiting step switches following temperature lowering from N2 dissociation to the hydrogenation of surface species.

Self-reported attention and hyperactivity symptoms among adults with epilepsy.

BACKGROUND: Patients with epilepsy (PWE) frequently have comorbid psychiatric disorders, the most common of which are depression and anxiety. Attention deficit disorder with hyperactivity (ADHD) is also more frequent among PWE, though that condition has been scarcely studied among the adult PWE population. OBJECTIVE: This study aimed to compare the presence of ADHD symptoms between adult PWE and the general population. METHODS: This was an observational case-control study. Ninety-five adult PWE from a tertiary center in southern Brazil were compared with 100 healthy controls. All subjects were submitted to three structured scales: 1) the World Health Organization Adult ADHD Self-Report Scale version 1.1 (ASRS); 2) the Hospital Anxiety and Depression Scale (HADS); and 3) the Adverse Events Profile (AEP). Dichotomic variables were analyzed through chi-square test and Fisher's exact test, as appropriate, and non-parametric variables were analyzed through the Mann-Whitney U test. RESULTS: Medians and interquartile ranges (IR) were: 1) ASRS: 26.00 (IR: 18 to 38) among PWE versus 17.00 (IR: 11 to 24) among controls, p < 0.001; 2) HADS: 14.00 (IR: 8 to 21) among PWE versus 11.00 (IR: 8 to 16) among controls, p = 0.007; 3) AEP: 3800 (IR: 31 to 49) among PWE versus 33.00 (IR: 23 to 43) among controls, p = 0.001. CONCLUSION: PWE showed a higher burden of symptoms of ADHD, depression, and anxiety when compared with controls, which replicates in the Brazilian population the findings of current literature that point toward a higher prevalence of such disorders among PWE.

ANTECEDENTES: Pacientes com epilepsia (PCE) frequentemente apresentam comorbidades psiquiátricas, principalmente depressão e ansiedade. O transtorno do déficit de atenção e hiperatividade (TDAH) também é mais frequente nos PCE, porém foi pouco estudado na população adulta de PCE. OBJETIVO: Comparar a presença de sintomas de TDAH entre PCE adultos e a população geral. MéTODOS: Noventa e cinco PCE adultos de um centro terciário no Sul do Brasil foram comparados a 100 controles saudáveis. Todos os sujeitos foram submetidos a três escalas estruturadas: 1) a Escala Autorrelatada de TDAH em Adultos da Organização Mundial da Saúde, versão 1.1 (ASRS); 2) a Escala Hospitalar de Ansiedade e Depressão (HADS); e 3) o Perfil de Eventos Adversos (AEP). Variáveis dicotômicas foram analisadas através dos testes chi-quadrado e exato de Fisher, conforme apropriado, e as variáveis não paramétricas foram analisadas através do teste U de Mann-Whitney. RESULTADOS: As medianas e os intervalos interquartis (IIQ) foram: 1) ASRS: 26.00 (IIQ: 18 a 38) em PCE versus 17.00 (IIQ: 11 a 24) nos controles, p < 0,001; 2) HADS: 14.00 (IIQ: 8 a 21) em PCE versus 11.00 (IIQ: 8 a 16) nos controles, p = 0,007; 3) AEP: 38.00 (IIQ: 31 a 49) em PCE versus 33.00 (IIQ: 23 a 43) nos controles, p = 0,001. CONCLUSãO: PCE apresentaram uma maior carga de sintomas de TDAH, depressão e ansiedade quando comparados aos controles, o que replica na população brasileira os achados da literatura atual, que apontam para uma maior prevalência de tais transtornos entre PCE.

Variational Pair-Density Functional Theory: Dealing with Strong Correlation at the Protein Scale.

Multiconfigurational pair-density functional theory (MC-PDFT) offers a promising solution to the challenges faced by traditional density functional theory (DFT) in addressing molecular systems containing transition metals, open-shells, or strong correlations in general. By utilizing both the density and on-top pair-density, MC-PDFT can make use of a more flexible multiconfigurational wave function to capture the necessary static correlation, while the pair-density functional also includes the effect of dynamic correlation. So far, MC-PDFT has been used after a multiconfigurational self-consistent field (MCSCF) step, using the orbitals and configuration interaction coefficients from the converged MCSCF wave function to compute PDFT energies and properties. Here, instead, we propose to perform a direct optimization of the wave function using the pair-density functionals, resulting in a variational formulation of MC-PDFT. We derive the expressions for the wave function gradient and illustrate their similarity to standard MCSCF equations. Furthermore, we illustrate the accuracy on a set of singlet-triplet gaps as well as dissociation curves. Our findings highlight one of MC-PDFT's standout features: a reduced dependency on the active space size compared to conventional multiconfigurational wave function methodologies. Additionally, we show that the computational cost of MC-PDFT is potentially lower than MCSCF and often on-par with standard Kohn-Sham DFT, which is demonstrated by performing a MC-PDFT calculation of the entire ferredoxin protein with 1447 atoms and nearly 12 000 basis functions.

Clinical research on extreme longevity: The FACET experience.

People with extreme longevity represent a unique model to study the biology of aging. Unfortunately, their inclusion in research projects is challenging with the consequent lack of evidence and the need to rely on small convenience samples. Given the growing global aging population, especially in the segment of the oldest old (i.e., aged 90 and older), research in this population has become crucial. Furthermore, by studying the characteristics of extremely longeval persons, it might be possible to 1) better understand the mechanisms of aging, and 2) identify endogenous or exogenous factors contributing to a long life. The design and implementation of research activities in the oldest people need special consideration and a pragmatic approach. Possible implementable solutions and suggestions are provided from experience gained during the conduction of the FAtigue in CEnTenarians (FACET) study.

Self-reported attention and hyperactivity symptoms among adults with epilepsy / Sintomas de desatenção e hiperatividade autorrelatados entre adultos com epilepsia

Abstract Background Patients with epilepsy (PWE) frequently have comorbid psychiatric disorders, the most common of which are depression and anxiety. Attention deficit disorder with hyperactivity (ADHD) is also more frequent among PWE, though that condition has been scarcely studied among the adult PWE population. Objective This study aimed to compare the presence of ADHD symptoms between adult PWE and the general population. Methods This was an observational case-control study. Ninety-five adult PWE from a tertiary center in southern Brazil were compared with 100 healthy controls. All subjects were submitted to three structured scales: 1) the World Health Organization Adult ADHD Self-Report Scale version 1.1 (ASRS); 2) the Hospital Anxiety and Depression Scale (HADS); and 3) the Adverse Events Profile (AEP). Dichotomic variables were analyzed through chi-square test and Fisher's exact test, as appropriate, and non-parametric variables were analyzed through the Mann-Whitney U test. Results Medians and interquartile ranges (IR) were: 1) ASRS: 26.00 (IR: 18 to 38) among PWE versus 17.00 (IR: 11 to 24) among controls, p< 0.001; 2) HADS: 14.00 (IR: 8 to 21) among PWE versus 11.00 (IR: 8 to 16) among controls, p= 0.007; 3) AEP: 3800 (IR: 31 to 49) among PWE versus 33.00 (IR: 23 to 43) among controls, p= 0.001. Conclusion PWE showed a higher burden of symptoms of ADHD, depression, and anxiety when compared with controls, which replicates in the Brazilian population the findings of current literature that point toward a higher prevalence of such disorders among PWE.

Resumo Antecedentes Pacientes com epilepsia (PCE) frequentemente apresentam comorbidades psiquiátricas, principalmente depressão e ansiedade. O transtorno do déficit de atenção e hiperatividade (TDAH) também é mais frequente nos PCE, porém foi pouco estudado na população adulta de PCE. Objetivo Comparar a presença de sintomas de TDAH entre PCE adultos e a população geral. Métodos Noventa e cinco PCE adultos de um centro terciário no Sul do Brasil foram comparados a 100 controles saudáveis. Todos os sujeitos foram submetidos a três escalas estruturadas: 1) a Escala Autorrelatada de TDAH em Adultos da Organização Mundial da Saúde, versão 1.1 (ASRS); 2) a Escala Hospitalar de Ansiedade e Depressão (HADS); e 3) o Perfil de Eventos Adversos (AEP). Variáveis dicotômicas foram analisadas através dos testes chi-quadrado e exato de Fisher, conforme apropriado, e as variáveis não paramétricas foram analisadas através do teste U de Mann-Whitney. Resultados As medianas e os intervalos interquartis (IIQ) foram: 1) ASRS: 26.00 (IIQ: 18 a 38) em PCE versus 17.00 (IIQ: 11 a 24) nos controles, p< 0,001; 2) HADS: 14.00 (IIQ: 8 a 21) em PCE versus 11.00 (IIQ: 8 a 16) nos controles, p= 0,007; 3) AEP: 38.00 (IIQ: 31 a 49) em PCE versus 33.00 (IIQ: 23 a 43) nos controles, p= 0,001. Conclusão PCE apresentaram uma maior carga de sintomas de TDAH, depressão e ansiedade quando comparados aos controles, o que replica na população brasileira os achados da literatura atual, que apontam para uma maior prevalência de tais transtornos entre PCE.

Women have a greater cardiac vagal withdrawal to heat stress compared to men.

The heated environment shifts the sympatho-vagal balance toward sympathetic predominance and vagal withdrawal. Women's heart is more reliant on vagal autonomic control, while men's heart is more dependent on sympathetic control. However, sex differences in cardiovascular autonomic responses to heat stress remain unknown. We aimed to investigate the cardiovascular autonomic regulation under heat stress between sexes. Thirty-two young participants (27 ± 4 years old; 16 women) were enrolled in a single visit, resting for 30min at baseline (thermal reference condition TC; ∼24°C) and 30min under a heated environment (HOT; ∼38°C). Blood pressure (BP), skin temperature, electrocardiogram, and respiratory oscillations were continuously recorded. The heart rate variability (HRV) was assessed by spectral analysis (low-frequency [LFnu; sympathetic and vagal] and high-frequency [HFnu; vagal]), and symbolic analysis (0 V% [sympathetic] and 2UV%, and 2LV% [vagal]). The spontaneous baroreflex sensitivity (BRS) was calculated by the gain between BP and R-R within the LF band (αLF). The estimated maximal aerobic capacity and body surface area were employed as covariates in sex comparisons. The effects of HOT were the following: 1) Women have a greater cardiac vagal withdrawal to heat stress compared to men; 2) Sex differences on cardiac autonomic response to heat stress exist after controlling for the effect of estimated physical fitness and body surface area. Therefore, heat stress provokes a higher vagal withdrawal to the heart in women compared to men. It could be attributed to sex per se since significant differences between men and women were not modified after covariate analysis.

Multiconfigurational Pair-Density Functional Theory Is More Complex than You May Think.

Multiconfigurational pair-density functional theory (MC-PDFT) is a promising way to describe both strong and dynamic correlations in an inexpensive way. The functionals in MC-PDFT are often "translated" from standard spin density functionals. However, these translated functionals can in principle lead to "translated spin densities" with a nonzero imaginary component. Current developments so far neglect this imaginary part by simply setting it to zero. In this work, we show how this imaginary component is actually needed to reproduce the correct physical behavior in a range of cases, especially low-spin open shells. We showcase the resulting formalism on both local density approximation and generalized gradient approximation functionals and illustrate the numerical behavior by benchmarking a number of singlet-triplet splittings (ST gaps) of organic diradicals and low-lying excited states of some common organic molecules. The results demonstrate that this scheme improves existing translated functionals and gives more accurate results, even with minimal active spaces.

Detection of alternative DNA structures and its implications for human disease.

Around 3% of the genome consists of simple DNA repeats that are prone to forming alternative (non-B) DNA structures, such as hairpins, cruciforms, triplexes (H-DNA), four-stranded guanine quadruplexes (G4-DNA), and others, as well as composite RNA:DNA structures (e.g., R-loops, G-loops, and H-loops). These DNA structures are dynamic and favored by the unwinding of duplex DNA. For many years, the association of alternative DNA structures with genome function was limited by the lack of methods to detect them in vivo. Here, we review the recent advancements in the field and present state-of-the-art technologies and methods to study alternative DNA structures. We discuss the limitations of these methods as well as how they are beginning to provide insights into causal relationships between alternative DNA structures, genome function and stability, and human disease.

A comparison of stomatal conductance responses to blue and red light between C3 and C4 photosynthetic species in three phylogenetically-controlled experiments.

Introduction: C4 photosynthesis is an adaptation that has independently evolved at least 66 times in angiosperms. C4 plants, unlike their C3 ancestral, have a carbon concentrating mechanism which suppresses photorespiration, often resulting in faster photosynthetic rates, higher yields, and enhanced water use efficiency. Moreover, the presence of C4 photosynthesis greatly alters the relation between CO2 assimilation and stomatal conductance. Previous papers have suggested that the adjustment involves a decrease in stomatal density. Here, we tested if C4 species also have differing stomatal responses to environmental cues, to accommodate the modified CO2 assimilation patterns compared to C3 species. Methods: To test this hypothesis, stomatal responses to blue and red-light were analysed in three phylogenetically linked pairs of C3 and C4 species from the Cleomaceae (Gynandropsis and Tarenaya), Flaveria, and Alloteropsis, that use either C3 or C4 photosynthesis. Results: The results showed strongly decreased stomatal sensitivity to blue light in C4 dicots, compared to their C3 counterparts, which exhibited significant blue light responses. In contrast, in C3 and C4 subspecies of the monocot A. semialata, the blue light response was observed regardless of photosynthetic type. Further, the quantitative red-light response varied across species, but the presence or absence of a significant stomatal red-light response was not directly associated with differences in photosynthetic pathway. Interestingly, stomatal density and morphology patterns observed across the three comparisons were also not consistent with patterns commonly asserted for C3 and C4 species. Discussion: The strongly diminished blue-light sensitivity of stomatal responses in C4 species across two of the comparisons suggests a common C4 feature that may have functional implications. Altogether, the strong prevalence of species-specific effects clearly emphasizes the importance of phylogenetic controls in comparisons between C3 and C4 photosynthetic pathways.

In vivo reduction of RAD51-mediated homologous recombination triggers aging but impairs oncogenesis.

Homologous recombination (HR) is a prominent DNA repair pathway maintaining genome integrity. Mutations in many HR genes lead to cancer predisposition. Paradoxically, the implication of the pivotal HR factor RAD51 on cancer development remains puzzling. Particularly, no RAD51 mouse models are available to address the role of RAD51 in aging and carcinogenesis in vivo. We engineered a mouse model with an inducible dominant-negative form of RAD51 (SMRad51) that suppresses RAD51-mediated HR without stimulating alternative mutagenic repair pathways. We found that in vivo expression of SMRad51 led to replicative stress, systemic inflammation, progenitor exhaustion, premature aging and reduced lifespan, but did not trigger tumorigenesis. Expressing SMRAD51 in a breast cancer predisposition mouse model (PyMT) decreased the number and the size of tumors, revealing an anti-tumor activity of SMRAD51. We propose that these in vivo phenotypes result from chronic endogenous replication stress caused by HR decrease, which preferentially targets progenitors and tumor cells. Our work underlines the importance of RAD51 activity for progenitor cell homeostasis, preventing aging and more generally for the balance between cancer and aging.

Pathogenic CANVAS (AAGGG)n repeats stall DNA replication due to the formation of alternative DNA structures.

CANVAS is a recently characterized repeat expansion disease, most commonly caused by homozygous expansions of an intronic (A2G3)n repeat in the RFC1 gene. There are a multitude of repeat motifs found in the human population at this locus, some of which are pathogenic and others benign. In this study, we conducted structure-functional analyses of the main pathogenic (A2G3)n and the main nonpathogenic (A4G)n repeats. We found that the pathogenic, but not the nonpathogenic, repeat presents a potent, orientation-dependent impediment to DNA polymerization in vitro. The pattern of the polymerization blockage is consistent with triplex or quadruplex formation in the presence of magnesium or potassium ions, respectively. Chemical probing of both repeats in supercoiled DNA reveals triplex H-DNA formation by the pathogenic repeat. Consistently, bioinformatic analysis of the S1-END-seq data from human cell lines shows preferential H-DNA formation genome-wide by (A2G3)n motifs over (A4G)n motifs in vivo. Finally, the pathogenic, but not the non-pathogenic, repeat stalls replication fork progression in yeast and human cells. We hypothesize that CANVAS-causing (A2G3)n repeat represents a challenge to genome stability by folding into alternative DNA structures that stall DNA replication.

Transcutaneous auricular branch vagal nerve stimulation as a non-invasive add-on therapeutic approach for pain in systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune disease with health-related quality of life (HRQoL) high impairment. Pain is of paramount importance to be targeted by therapeutical approaches. Our study aim was to perform an add-on device-based non-invasive neuromodulatory treatment through transcutaneous auricular vagal nerve stimulation (tVNS) in patients with SSc, assessing its effects on pain as primary endpoint and on inflammation, cardiovascular autonomic control and HRQoL. METHODS: Thirty-two patients with SSc were enrolled based on reported pain assessed through Numeric Rating Scale (NRS). Twenty-one (90% with limited cutaneous SSc) completed a randomised, cross-over, patient-blind trial, in which interventional and active control were used in random order for 4 weeks, interspersed with 4 weeks washout. NRS, Patient-Reported Outcomes Measurement Information System-29 (PROMIS-29) Item4 for pain interference, heart rate variability (HRV), serum cytokines and HRQoL questionnaires (Health Assessment Questionnaire, Patient Health Questionnaire-9, University of California, Los Angeles Gastrointestinal Tract, Pittsburgh Sleep Quality Index) were assessed at baseline, at T1 (after 1 month of tVNS or active control), at T2 (after washout) and at T3 (after 1 month of active control or tVNS). T-test for paired data and Wilcoxon signed-rank test for non-normally distributed parameters were performed to compare the effect of tVNS and active control. RESULTS: NRS pain was significantly reduced by tVNS and not by active control (Mean±SD: -27.7%±21.3% vs -7.7%±26.3%, p=0.002). Interleukin-6 was downregulated in tVNS versus active control (p=0.029). No significant differences were observed in tVNS versus active control for PROMIS-29 Item4, QoL scales and HRV with both spectral and symbolic analyses. CONCLUSION: tVNS demonstrated to be a safe and non-invasive add-on tool to reduce pain in SSc.