Histological Alterations in Placentas of Pregnant Women with SARS-CoV-2 Infection: A Single-Center Case Series.

This study aimed to investigate the histopathological changes associated with SARS-CoV-2 infection in placentas. A case series of anatomopathological analysis was conducted on the placentas of pregnant women with SARS-CoV-2 who delivered between March and December 2020 at Santo Amaro Hospital (HSA) in Salvador, Brazil. Out of the 29 placentas examined, the median weight was 423.0 (IQR: 385.0-521.0) g. Among them, 58.3% (n = 14) had inadequate weight relative to the newborn's weight. The histopathological findings revealed that 86.2% (n = 25) of the placentas had poorly defined lobes, and the fetal and maternal surface color was normal in 89.7% (n = 26) and 93.1% (n = 27), respectively. Additionally, 51.7% (n = 15) of the umbilical cords displayed hypercoiling. The most frequent microscopic finding was infarction, present in 35.3% (n = 6) of the cases, followed by 11.8% (n = 2) for each of chorioamnionitis, chronic villitis, focal perivillositis, and laminar necrosis. Analysis of the umbilical cords identified 23.5% (n = 4) cases of intervillous thrombosis, while amnion analysis showed 13.8% (n = 4) cases of squamous metaplasia. Extraplacental membrane examination revealed fibrin deposition in 93.1% (n = 27) of the cases, necrosis in 62.0% (n = 18), calcifications in 51.7% (n = 15), cysts in 37.9% (n = 11), neutrophilic exudate in 17.2% (n = 5), thrombosis in 13.7% (n = 4), and delayed placental maturation in 6.9% (n = 2). All analyzed placentas exhibited histopathological changes, primarily vascular and inflammatory, which indicate SARS-CoV-2 infection in term pregnancies. These alterations could be associated with impaired placental function, fetal growth restriction, preeclampsia, and prematurity. However, further prospective studies are required to validate the type, prevalence, and prognosis of each of these changes.

Malonyl-CoA is a conserved endogenous ATP-competitive mTORC1 inhibitor.

Cell growth is regulated by the mammalian/mechanistic target of rapamycin complex 1 (mTORC1), which functions both as a nutrient sensor and a master controller of virtually all biosynthetic pathways. This ensures that cells are metabolically active only when conditions are optimal for growth. Notably, although mTORC1 is known to regulate fatty acid biosynthesis, how and whether the cellular lipid biosynthetic capacity signals back to fine-tune mTORC1 activity remains poorly understood. Here we show that mTORC1 senses the capacity of a cell to synthesise fatty acids by detecting the levels of malonyl-CoA, an intermediate of this biosynthetic pathway. We find that, in both yeast and mammalian cells, this regulation is direct, with malonyl-CoA binding to the mTOR catalytic pocket and acting as a specific ATP-competitive inhibitor. When fatty acid synthase (FASN) is downregulated/inhibited, elevated malonyl-CoA levels are channelled to proximal mTOR molecules that form direct protein-protein interactions with acetyl-CoA carboxylase 1 (ACC1) and FASN. Our findings represent a conserved and unique homeostatic mechanism whereby impaired fatty acid biogenesis leads to reduced mTORC1 activity to coordinately link this metabolic pathway to the overall cellular biosynthetic output. Moreover, they reveal the existence of a physiological metabolite that directly inhibits the activity of a signalling kinase in mammalian cells by competing with ATP for binding.

Decreased spliceosome fidelity and egl-8 intron retention inhibit mTORC1 signaling to promote longevity.

Changes in splicing fidelity are associated with loss of homeostasis and aging, yet only a handful of splicing factors have been shown to be causally required to promote longevity, and the underlying mechanisms and downstream targets in these paradigms remain elusive. Surprisingly, we found a hypomorphic mutation within ribonucleoprotein RNP-6/poly(U)-binding factor 60 kDa (PUF60), a spliceosome component promoting weak 3'-splice site recognition, which causes aberrant splicing, elevates stress responses and enhances longevity in Caenorhabditis elegans. Through genetic suppressor screens, we identify a gain-of-function mutation within rbm-39, an RNP-6-interacting splicing factor, which increases nuclear speckle formation, alleviates splicing defects and curtails longevity caused by rnp-6 mutation. By leveraging the splicing changes induced by RNP-6/RBM-39 activities, we uncover intron retention in egl-8/phospholipase C ß4 (PLCB4) as a key splicing target prolonging life. Genetic and biochemical evidence show that neuronal RNP-6/EGL-8 downregulates mammalian target of rapamycin complex 1 (mTORC1) signaling to control organismal lifespan. In mammalian cells, PUF60 downregulation also potently and specifically inhibits mTORC1 signaling. Altogether, our results reveal that splicing fidelity modulates lifespan through mTOR signaling.

The Multifaceted Role of Nutrient Sensing and mTORC1 Signaling in Physiology and Aging.

The mechanistic Target of Rapamycin (mTOR) is a growth-related kinase that, in the context of the mTOR complex 1 (mTORC1), touches upon most fundamental cellular processes. Consequently, its activity is a critical determinant for cellular and organismal physiology, while its dysregulation is commonly linked to human aging and age-related disease. Presumably the most important stimulus that regulates mTORC1 activity is nutrient sufficiency, whereby amino acids play a predominant role. In fact, mTORC1 functions as a molecular sensor for amino acids, linking the cellular demand to the nutritional supply. Notably, dietary restriction (DR), a nutritional regimen that has been shown to extend lifespan and improve healthspan in a broad spectrum of organisms, works via limiting nutrient uptake and changes in mTORC1 activity. Furthermore, pharmacological inhibition of mTORC1, using rapamycin or its analogs (rapalogs), can mimic the pro-longevity effects of DR. Conversely, nutritional amino acid overload has been tightly linked to aging and diseases, such as cancer, type 2 diabetes and obesity. Similar effects can also be recapitulated by mutations in upstream mTORC1 regulators, thus establishing a tight connection between mTORC1 signaling and aging. Although the role of growth factor signaling upstream of mTORC1 in aging has been investigated extensively, the involvement of signaling components participating in the nutrient sensing branch is less well understood. In this review, we provide a comprehensive overview of the molecular and cellular mechanisms that signal nutrient availability to mTORC1, and summarize the role that nutrients, nutrient sensors, and other components of the nutrient sensing machinery play in cellular and organismal aging.

Tweeting for Nutrition: Feasibility and Efficacy Outcomes of a 6-Week Social Media-Based Nutrition Education Intervention for Student-Athletes.

Coccia, C, Fernandes, SM, and Altiti, J. Tweeting for nutrition: feasibility and efficacy outcomes of a 6-week social media-based nutrition education intervention for student-athletes. J Strength Cond Res 34(7): 2084-2092, 2020-The main objective of this study was to determine the feasibility and efficacy of a social media-based nutrition intervention using Twitter on nutrition knowledge, dietary practices, body mass index (BMI), self-efficacy, and social support among student-athletes. Participants included 50 male and female National Collegiate Athletic Association Division I student-athletes between the ages of 18 and 24 years. Data were collected in October 2014. The study design employed a 6-week social media intervention using Twitter, to increase nutrition knowledge, self-efficacy, social support, and dietary adherence to the recommendations from the Dietary Guidelines for Americans. Descriptive statistics were calculated for all study variables and pre-post differences were assessed using paired t-tests. The results indicate a 6-week nutrition intervention delivered solely through social media resulted in increased nutrition knowledge (t = -2.23; p = 0.035), reduced fat intake (t = -1.57; p = 0.13), and decreased BMI (t = 2.32; p = 0.027) in student-athletes. In conclusion, social media-based nutrition education may provide university-based strength and conditioning coaches and other sports practitioners with a tool for widespread and timely access to students to facilitate healthy dietary behaviors.

Altered in vitro muscle differentiation in X-linked myopathy with excessive autophagy.

X-linked myopathy with excessive autophagy (XMEA) is a genetic disease associated with weakness of the proximal muscles. It is caused by mutations in the VMA21 gene, coding for a chaperone that functions in the vacuolar ATPase (v-ATPase) assembly. Mutations associated with lower content of assembled v-ATPases lead to an increase in lysosomal pH, culminating in partial blockage of macroautophagy, with accumulation of vacuoles of undigested content. Here, we studied a 5-year-old boy affected by XMEA, caused by a small indel in the VMA21 gene. Detection of sarcoplasmic Lc3 (also known as MAP1LC3B)-positive vacuoles in his muscle biopsy confirmed an autophagy defect. To understand how autophagy is regulated in XMEA myogenesis, we used patient-derived muscle cells to evaluate autophagy during in vitro muscle differentiation. An increase in lysosomal pH was observed in the patient's cells, compatible with predicted functional defect of his mutation. Additionally, there was an increase in autophagic flux in XMEA myotubes. Interestingly, we observed that differentiation of XMEA myoblasts was altered, with increased myotube formation observed through a higher fusion index, which was not dependent on lysosomal acidification. Moreover, no variation in the expression of myogenic factors nor the presence of regenerating fibers in the patient's muscle were observed. Myoblast fusion is a tightly regulated process; therefore, the uncontrolled fusion of XMEA myoblasts might generate cells that are not as functional as normal muscle cells. Our data provide new evidence on the reason for predominant muscle involvement in the context of the XMEA phenotype.This article has an associated First Person interview with the first author of the paper.

Muscle satellite cells and impaired late stage regeneration in different murine models for muscular dystrophies.

Satellite cells (SCs) are the main muscle stem cells responsible for its regenerative capacity. In muscular dystrophies, however, a failure of the regenerative process results in muscle degeneration and weakness. To analyze the effect of different degrees of muscle degeneration in SCs behavior, we studied adult muscle of the dystrophic strains: DMDmdx, Largemyd, DMDmdx/Largemyd, with variable histopathological alterations. Similar results were observed in the dystrophic models, which maintained normal levels of PAX7 expression, retained the Pax7-positive SCs pool, and their proliferation capacity. Moreover, elevated expression of MYOG, an important myogenic factor, was also observed. The ability to form new fibers was verified by the presence of dMyHC positive regenerating fibers. However, those fibers had incomplete maturation characteristics, such as small and homogenous fiber caliber, which could contribute to their dysfunction. We concluded that dystrophic muscles, independently of their degeneration degree, retain their SCs pool with proliferating and regenerative capacities. Nonetheless, the maturation of these new fibers is incomplete and do not prevent muscle degeneration. Taken together, these results suggest that the improvement of late muscle regeneration should better contribute to therapeutic approaches.

Faster regeneration associated to high expression of Fam65b and Hdac6 in dysferlin-deficient mouse.

Dysferlin is a sarcolemmal muscle protein associated with the processes of membrane repair, trafficking, and fusion of intracellular vesicles and muscle regeneration. Mutations in the DYSF gene cause clinically distinct forms of muscular dystrophies. The dysferlin-deficient SJL/J mouse model presents a reduction of 85% of the protein but shows mild weakness and discrete histopathological alterations. To study the effect of dysferlin deficiency in the muscle regenerative process, we used a model of electrical injury by electroporation to induce muscle degeneration/regeneration in the SJL/J mouse. The relative expression of the genes Pax7, MyoD, Myf5, and Myog was accompanied by the histopathological evaluation during muscle recovery at different time points after injury. We also investigated the effects of dysferlin deficiency in the expression of genes encoding FAM65B and HDAC6 proteins, recently described as forming a tricomplex with dysferlin at the beginning of myoblast differentiation. We observed an altered time course through the process of degeneration and regeneration in dysferlin-deficient mice, with remarkable regenerative capacity characterized by a faster and effective response in the first days after injury, as compared to the WT mice. Also, dysferlin deficiency seems to significantly alter the gene expression of Fam65b and Hdac6 during regeneration, since higher levels of expression of both genes were observed in dysferlin-deficient mice. These results need further attention to define their relevance in the disease mechanism.

Do animal models hold value in Autism spectrum disorder (ASD) drug discovery?

Introduction: Autism spectrum disorder (ASD) defines impairments in a broad range of behaviors in two domains, social communication and repetitive behaviors and/or restricted interests. Drug discovery is ongoing for ASD, but no drugs have been approved for the core behaviors. Animal models are invaluable for drug discovery, but are limited by the face, construct, and predictive validity for ASD. The genetic construct validity of animal models has provided potential targets including biological events early in development which are indeed challenging to treat pharmacologically. Areas covered: The focus of this review is on the current models for ASD being used to test potential therapeutics. Drugs reviewed include sulforaphane, propranolol, oxytocin, vasopressin antagonists, arbaclofen, and bumetanide, that have been evaluated on behaviors with face validity for both the core behaviors of ASD, social and repetitive behaviors, and the modifying behaviors including learning and memory. Expert opinion: Animal models for the core symptoms of ASD have suffered from the same problems hampering research in humans, including lack of a biomarker, heterogeneity of symptom severity, and appropriate endpoints for evaluation. Despite this, the data from animal models has allowed several drugs to move on to clinical testing.

Muscle Satellite Cells: Exploring the Basic Biology to Rule Them.

Adult skeletal muscle is a postmitotic tissue with an enormous capacity to regenerate upon injury. This is accomplished by resident stem cells, named satellite cells, which were identified more than 50 years ago. Since their discovery, many researchers have been concentrating efforts to answer questions about their origin and role in muscle development, the way they contribute to muscle regeneration, and their potential to cell-based therapies. Satellite cells are maintained in a quiescent state and upon requirement are activated, proliferating, and fusing with other cells to form or repair myofibers. In addition, they are able to self-renew and replenish the stem pool. Every phase of satellite cell activity is highly regulated and orchestrated by many molecules and signaling pathways; the elucidation of players and mechanisms involved in satellite cell biology is of extreme importance, being the first step to expose the crucial points that could be modulated to extract the optimal response from these cells in therapeutic strategies. Here, we review the basic aspects about satellite cells biology and briefly discuss recent findings about therapeutic attempts, trying to raise questions about how basic biology could provide a solid scaffold to more successful use of these cells in clinics.

The mdx Mutation in the 129/Sv Background Results in a Milder Phenotype: Transcriptome Comparative Analysis Searching for the Protective Factors.

The mdx mouse is a good genetic and molecular murine model for Duchenne Muscular Dystrophy (DMD), a progressive and devastating muscle disease. However, this model is inappropriate for testing new therapies due to its mild phenotype. Here, we transferred the mdx mutation to the 129/Sv strain with the aim to create a more severe model for DMD. Unexpectedly, functional analysis of the first three generations of mdx129 showed a progressive amelioration of the phenotype, associated to less connective tissue replacement, and more regeneration than the original mdxC57BL. Transcriptome comparative analysis was performed to identify what is protecting this new model from the dystrophic characteristics. The mdxC57BL presents three times more differentially expressed genes (DEGs) than the mdx129 (371 and 137 DEGs respectively). However, both models present more overexpressed genes than underexpressed, indicating that the dystrophic and regenerative alterations are associated with the activation rather than repression of genes. As to functional categories, the DEGs of both mdx models showed a predominance of immune system genes. Excluding this category, the mdx129 model showed a decreased participation of the endo/exocytic pathway and homeostasis categories, and an increased participation of the extracellular matrix and enzymatic activity categories. Spp1 gene overexpression was the most significant DEG exclusively expressed in the mdx129 strain. This was confirmed through relative mRNA analysis and osteopontin protein quantification. The amount of the 66 kDa band of the protein, representing the post-translational product of the gene, was about 4,8 times higher on western blotting. Spp1 is a known DMD prognostic biomarker, and our data indicate that its upregulation can benefit phenotype. Modeling the expression of the DEGs involved in the mdx mutation with a benign course should be tested as a possible therapeutic target for the dystrophic process.

Silent polymorphisms in the RYR1 gene do not modify the phenotype of the p.4898 I>T pathogenic mutation in central core disease: a case report.

BACKGROUND: Central core disease is a congenital myopathy, characterized by presence of central core-like areas in muscle fibers. Patients have mild or moderate weakness, hypotonia and motor developmental delay. The disease is caused by mutations in the human ryanodine receptor gene (RYR1), which encodes a calcium-release channel. Since the RYR1 gene is huge, containing 106 exons, mutation screening has been limited to three 'hot spots', with particular attention to the C-terminal region. Recent next-generation sequencing methods are now identifying multiple numbers of variants in patients, in which interpretation and phenotype prevision is difficult. CASE PRESENTATION: In a Brazilian Caucasian family, clinical, histopathological and molecular analysis identified a new case of central core disease in a 48-year female. Sanger sequencing of the C-terminal region of the RYR1 gene identified two different missense mutations: c.14256 A > C polymorphism in exon 98 and c.14693 T > C in exon 102, which have already been described as pathogenic. Trans-position of the 2 mutations was confirmed because patient's daughter, mother and sister carried only the exon 98's mutation, a synonymous variant that was subsequently found in the frequency of 013-0,05 of alleles. Further next generation sequencing study of the whole RYR1 gene in the patient revealed the presence of additional 5 common silent polymorphisms in homozygosis and 8 polymorphisms in heterozygosis. CONCLUSIONS: Considering that patient's relatives showed no pathologic phenotype, and the phenotype presented by the patient is within the range observed in other central core disease patients with the same mutation, it was concluded that the c.14256 A > C polymorphism alone is not responsible for disease, and the associated additional silent polymorphisms are not acting as modifiers of the primary pathogenic mutation in the affected patient. The case described above illustrates the present reality where new methods for wide genome screening are becoming more accessible and able to identify a great variety of mutations and polymorphisms of unknown function in patients and their families.

Oligonucleotide-Based Therapy for FTD/ALS Caused by the C9orf72 Repeat Expansion: A Perspective.

Amyotrophic lateral sclerosis (ALS) is a progressive and lethal disease of motor neuron degeneration, leading to paralysis of voluntary muscles and death by respiratory failure within five years of onset. Frontotemporal dementia (FTD) is characterised by degeneration of frontal and temporal lobes, leading to changes in personality, behaviour, and language, culminating in death within 5-10 years. Both of these diseases form a clinical, pathological, and genetic continuum of diseases, and this link has become clearer recently with the discovery of a hexanucleotide repeat expansion in the C9orf72 gene that causes the FTD/ALS spectrum, that is, c9FTD/ALS. Two basic mechanisms have been proposed as being potentially responsible for c9FTD/ALS: loss-of-function of the protein encoded by this gene (associated with aberrant DNA methylation) and gain of function through the formation of RNA foci or protein aggregates. These diseases currently lack any cure or effective treatment. Antisense oligonucleotides (ASOs) are modified nucleic acids that are able to silence targeted mRNAs or perform splice modulation, and the fact that they have proved efficient in repeat expansion diseases including myotonic dystrophy type 1 makes them ideal candidates for c9FTD/ALS therapy. Here, we discuss potential mechanisms and challenges for developing oligonucleotide-based therapy for c9FTD/ALS.

Reduced brain natriuretic peptide levels in class III obesity: the role of metabolic and cardiovascular factors.

OBJECTIVE: Brain natriuretic peptide (BNP) has potent lipolytic action and, probably, a role in the biological mechanisms of obesity. Clinically, high levels are found in subjects with heart failure (HF). Low levels and inverse relation to BMI lead to questioning of its clinical utility in obese subjects, but heterogeneous results are found in severe obesity. METHODS: In order to describe BNP behavior and its metabolic and cardiovascular determinants in class III obesity, we performed BNP measurement as well as clinical and echocardiographic evaluation of 89 subjects from two public hospitals in Brazil. Multivariate logistic ordinal regression with BNP tertiles as the dependent variable was performed. RESULTS: Mean (± SD) age and BMI (± SD) was 44 ± 11.5 years and 53.2 ± 7.9 kg/m(2), respectively. 72 (81%) participants were women, and 18 (20%) had HF. Median BNP was 9.5 pg/ml(Q1 4.9; Q3 21.2 pg/ml). 30% of BNP values were below the detection limit of the method. In multivariate analysis, left atrial volume (LAV) was the only determinant of BNP levels (p 0.002) with odds-ratio of 1.1 (95% CI 1.03-1.16). CONCLUSION: BNP levels are low in severe obesity, even in subjects with HF. LAV, which marks diastolic dysfunction, determines BNP levels, but not BMI and metabolic abnormalities.

Optimization of novel acyl pyrrolidine inhibitors of hepatitis C virus RNA-dependent RNA polymerase leading to a development candidate.

Optimization of a pyrrolidine-based template using structure-based design and physicochemical considerations has provided a development candidate 20b (3082) with submicromolar potency in the HCV replicon and good pharmacokinetic properties.