Meiotic DSB patterning: A multifaceted process

Meiosis is a specialized two-step cell division responsible for genome haploidization and the generation of genetic diversity during gametogenesis. An integral and distinctive feature of the meiotic program is the evolutionarily conserved initiation of homologous recombination (HR) by the developmentally programmed induction of DNA double-strand breaks (DSBs). The inherently dangerous but essential act of DSB formation is subject to multiple forms of stringent and self-corrective regulation that collectively ensure fruitful and appropriate levels of genetic exchange without risk to cellular survival. Within this article we focus upon an emerging element of this control—spatial regulation—detailing recent advances made in understanding how DSBs are evenly distributed across the genome, and present a unified view of the underlying patterning mechanisms employed

Abordagem Clínica e Terapêutica de Doentes Internados por COVID-19: Uma Coorte Pediátrica em Portugal

Introduction: Coronavirus disease 2019, or COVID-19, in children is usually a mild disease, but severe illness has been reported. Currently, the therapy benefits of antiviral experimental drugs are still uncertain. The main aim of this study is to describe the experience of a level III hospital regarding therapeutic management of hospitalized children with COVID-19 and to characterize clinical features and evolution. Material and methods: This is a descriptive study of patients with COVID-19 in a level III pediatric hospital in Portugal between March and June 2020. Experimental drugs were administered according to the best scientific evidence at the time as 'off-label use'. Results: Among 200 children with SARS-CoV-2 infection, 37 were admitted due to COVID-19. Median age was one year (23 days - 18 years), 43% had comorbidities and 20/37 (54%) received antiviral therapy. Hydroxychloroquine was administered in 13 patients, in monotherapy or combined with lopinavir/ritonavir or azithromycin. Lopinavir/ritonavir was administered in eight patients and three children were treated with remdesivir. The patients who were treated had pneumonia (14), multisystem inflammatory syndrome in children (2), sepsis (2), myocarditis (1), acute respiratory distress syndrome (1), and mild illness with comorbidities (3). Other therapies included methylprednisolone and immunoglobulin (3), enoxaparin (2), antibiotics (16), oxygen (7), corticosteroids, and other inhaled therapy (16). Discussion: Several treatment approaches have been proposed for severe COVID-19, even though none of them had been proven effective or approved for small children. Currently, remdesivir is approved for children aged above 12 years-old. Although 54% of our patients were treated with antivirals, it is important to understand that the favorable clinical evolution could be related with the natural course of the disease. Conclusion: A significant proportion of our population presented severe and critical disease, was hospitalized and received treatment according to the most recent data, although most patients had mild disease. COVID-19 treatment in children is a clinical challenge and clinical trials are urgently needed.info:eu-repo/semantics/publishedVersio

Diagnostic Challenge in a Sickle Cell Disease Patient with COVID-19

Acute chest syndrome is a life-threatening complication in sickle cell disease. Infections are frequently implied, and like other viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be a trigger. In addition, due to their inflammatory status, they may present a higher risk for severe coronavirus disease 2019 (COVID-19). Pneumonia and acute chest syndrome share clinical, laboratory, and radiological features and may overlap, which makes their differential diagnosis especially challenging. We describe a case of an adolescent with homozygous sickle cell disease that developed acute chest syndrome in the context of COVID-19. With it, we intend to bring awareness to the potential role of imaging in the differential diagnosis and in establishing the best approach for the patient. Chest computed tomography findings were suggestive of an alternative diagnosis to COVID-19 pneumonia and red cell transfusion, fluid management, analgesics, and antibiotics were administered with favorable outcome.info:eu-repo/semantics/publishedVersio

Síndrome Inflamatória Multissistémica em Crianças Associada a COVID-19 num Hospital de Nível III em Portugal

Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe manifestation of coronavirus disease 2019 (COVID-19). The aim of this study was to describe the characteristics of children with MIS-C admitted to a pediatric tertiary hospital in Portugal. Material and methods: Observational descriptive study of MIS-C patients admitted between April 2020 and April 2021. Demographic and clinical characteristics, diagnostic tests, and treatment data were collected. The diagnosis of MIS-C was based on the World Health Organization and Centers for Disease Control and Prevention criteria. Results: We reported 45 children with MIS-C. The median age was seven years (IQR 4 - 10 years) and 60.0% were previously healthy. SARS-CoV-2 infection was confirmed in 77.8% by RT-PCR or antibody testing for SARS-CoV-2, and in 73.3%, an epidemiological link was confirmed. All the patients had a fever and organ system involvement: hematologic (100%), cardiovascular (97.8%), gastrointestinal (97.8%), mucocutaneous (86.7%), respiratory (26.7%), neurologic (15.6%), and renal (13.3%) system. Neurological (p = 0.035) and respiratory (p = 0.035) involvement were observed in patients with a more severe presentation. There was a significant difference of medians when comparing disease severity groups, namely in the values of hemoglobin (p = 0.015), lymphocytes (p = 0.030), D-dimer (p = 0.019), albumin (p < 0.001), NT-proBNP (p = 0.005), ferritin (p = 0.048), CRP (p = 0.006), procalcitonin (p = 0.005) and IL-6 (p = 0.002). From the total number of children, 93.3% received intravenous immunoglobulin, 91.1% methylprednisolone, and one patient (2.2%) received anakinra. Thirteen patients (28.8%) required intensive care and there were no deaths. Of the 21 patients evaluated, 90.4% had reduction of exercise capacity and of the 15 patients who underwent cardiac magnetic resonance, 53.3% had sequelae of cardiac injury. Conclusion: We observed a large spectrum of disease presentation in a group of patients where most were previously healthy. A small percentage of patients (28.9%) had a severe presentation of the disease. MIS-C is a challenge in current clinical practice and its diagnosis requires a high level of clinical suspicion as the timely initiation of therapy is essential to prevent complications. However, there is no scientific consensus on the treatment and follow-up of these patients.info:eu-repo/semantics/publishedVersio

Organizing pneumonia due to actinomycosis: an undescribed association

Organizing pneumonia is a pathologic entity characterized by intra-alveolar buds of granulation tissue that can extend to the bronchiolar lumen. It is a non-specific finding reflecting a pattern of pulmonary response to aggression that can be cryptogenic or associated with several causes. Pulmonary actinomycosis is a rare infectious disease, of bacterial aetiology, and of difficult diagnosis. This disease usually causes non-specific respiratory symptoms and radiological findings, and the treatment is based on the use of antibiotics. The authors describe a clinical case of a 53-year-old male smoker (50 pack years), initially seen for complaints of right-sided chest pain and sub-febrile temperature. Imaging studies revealed a mass in the inferior right lobe and enlarged mediastinal lymph nodes. Empirical treatment with antibiotics caused partial and temporary improvement. Transthoracic biopsy revealed a pattern of organizing pneumonia with giant multinucleated cell granulomas. Repeat imaging studies revealed an enlargement of the pulmonary mass and therefore a right inferior lobectomy was performed. The pathologic study revealed a histological pattern of organizing pneumonia surrounding inflammatory bronchiectasis with a large number of Actinomyces colonies. To our knowledge there is presently no report in the literature of organizing pneumonia associated with Actinomyces infection

Carbonization of a radicular cyst using fiber-optic diode laser: a case report

A female patient, 51 years old, complaint of painful swelling on the anatomical area of the upper left lateral incisor. The diagnosis of radicular cyst was confirmed histo-pathologically. Nowadays, radicular cysts may be treated using conventional root canal methods or surgical apicectomy. The possible soft-laser reaction to radicular cysts after contact application has not been investigated. We present an in vitro case of a diagnosed radicular cyst which carbonized after contact application of diode laser. The need for future clinical trials will be essential to prove the sensitivity of this procedure in humans

Calcisponges have a ParaHox gene and dynamic expression of dispersed NK homeobox genes

This study was funded by the Sars Centre core budget to M. Adamska. Sequencing was performed at the Norwegian High Throughput Sequencing Centre funded by the Norwegian Research Council. O.M.R. and D.E.K.F. acknowledge support from the BBSRC and the School of Biology, University of St Andrews.Sponges are simple animals with few cell types, but their genomes paradoxically contain a wide variety of developmental transcription factors1,2,3,4, including homeobox genes belonging to the Antennapedia (ANTP) class5,6, which in bilaterians encompass Hox, ParaHox and NK genes. In the genome of the demosponge Amphimedon queenslandica, no Hox or ParaHox genes are present, but NK genes are linked in a tight cluster similar to the NK clusters of bilaterians5. It has been proposed that Hox and ParaHox genes originated from NK cluster genes after divergence of sponges from the lineage leading to cnidarians and bilaterians5,7. On the other hand, synteny analysis lends support to the notion that the absence of Hox and ParaHox genes in Amphimedon is a result of secondary loss (the ghost locus hypothesis)8. Here we analysed complete suites of ANTP-class homeoboxes in two calcareous sponges, Sycon ciliatum and Leucosolenia complicata. Our phylogenetic analyses demonstrate that these calcisponges possess orthologues of bilaterian NK genes (Hex, Hmx and Msx), a varying number of additional NK genes and one ParaHox gene, Cdx. Despite the generation of scaffolds spanning multiple genes, we find no evidence of clustering of Sycon NK genes. All Sycon ANTP-class genes are developmentally expressed, with patterns suggesting their involvement in cell type specification in embryos and adults, metamorphosis and body plan patterning. These results demonstrate that ParaHox genes predate the origin of sponges, thus confirming the ghost locus hypothesis8, and highlight the need to analyse the genomes of multiple sponge lineages to obtain a complete picture of the ancestral composition of the first animal genome.PostprintPeer reviewe

A model for selection of eyespots on butterfly wings

The development of eyespots on the wing surface of butterflies of the family Nympalidae is one of the most studied examples of biological pattern formation.However, little is known about the mechanism that determines the number and precise locations of eyespots on the wing. Eyespots develop around signaling centers, called foci, that are located equidistant from wing veins along the midline of a wing cell (an area bounded by veins). A fundamental question that remains unsolved is, why a certain wing cell develops an eyespot, while other wing cells do not. We illustrate that the key to understanding focus point selection may be in the venation system of the wing disc. Our main hypothesis is that changes in morphogen concentration along the proximal boundary veins of wing cells govern focus point selection. Based on previous studies, we focus on a spatially two-dimensional reaction-diffusion system model posed in the interior of each wing cell that describes the formation of focus points. Using finite element based numerical simulations, we demonstrate that variation in the proximal boundary condition is sufficient to robustly select whether an eyespot focus point forms in otherwise identical wing cells. We also illustrate that this behavior is robust to small perturbations in the parameters and geometry and moderate levels of noise. Hence, we suggest that an anterior-posterior pattern of morphogen concentration along the proximal vein may be the main determinant of the distribution of focus points on the wing surface. In order to complete our model, we propose a two stage reaction-diffusion system model, in which an one-dimensional surface reaction-diffusion system, posed on the proximal vein, generates the morphogen concentrations that act as non-homogeneous Dirichlet (i.e., fixed) boundary conditions for the two-dimensional reaction-diffusion model posed in the wing cells. The two-stage model appears capable of generating focus point distributions observed in nature. We therefore conclude that changes in the proximal boundary conditions are sufficient to explain the empirically observed distribution of eyespot focus points on the entire wing surface. The model predicts, subject to experimental verification, that the source strength of the activator at the proximal boundary should be lower in wing cells in which focus points form than in those that lack focus points. The model suggests that the number and locations of eyespot foci on the wing disc could be largely controlled by two kinds of gradients along two different directions, that is, the first one is the gradient in spatially varying parameters such as the reaction rate along the anterior-posterior direction on the proximal boundary of the wing cells, and the second one is the gradient in source values of the activator along the veins in the proximal-distal direction of the wing cell