Hox genes control homocercal caudal fin development and evolution.

Ancient bony fishes had heterocercal tails, like modern sharks and sturgeons, with asymmetric caudal fins and a vertebral column extending into an elongated upper lobe. Teleost fishes, in contrast, developed a homocercal tail characterized by two separate equal-sized fin lobes and the body axis not extending into the caudal fin. A similar heterocercal-to-homocercal transition occurs during teleost ontogeny, although the underlying genetic and developmental mechanisms for either transition remain unresolved. Here, we investigated the role of hox13 genes in caudal fin formation as these genes control posterior identity in animals. Analysis of expression profiles of zebrafish hox13 paralogs and phenotypes of CRISPR/Cas9-induced mutants showed that double hoxb13a and hoxc13a mutants fail to form a caudal fin. Furthermore, single mutants display heterocercal-like morphologies not seen since Mesozoic fossil teleosteomorphs. Relaxation of functional constraints after the teleost genome duplication may have allowed hox13 duplicates to neo- or subfunctionalize, ultimately contributing to the evolution of a homocercal tail in teleost fishes.

Using Zebrafish to Dissect the Interaction of Mycobacteria with the Autophagic Machinery in Macrophages.

Existing drug treatment against tuberculosis is no match against the increasing number of multi-drug resistant strains of its causative agent, Mycobacterium tuberculosis (Mtb). A better understanding of how mycobacteria subvert the host immune defenses is crucial for developing novel therapeutic strategies. A potential approach is enhancing the activity of the autophagy machinery, which can direct bacteria to autophagolysosomal degradation. However, the interplay specifics between mycobacteria and the autophagy machinery must be better understood. Here, we analyzed live imaging data from the zebrafish model of tuberculosis to characterize mycobacteria-autophagy interactions during the early stages of infection in vivo. For high-resolution imaging, we microinjected fluorescent Mycobacterium marinum (Mm) into the tail fin tissue of zebrafish larvae carrying the GFP-LC3 autophagy reporter. We detected phagocytosed Mm clusters and LC3-positive Mm-containing vesicles within the first hour of infection. LC3 associations with these vesicles were transient and heterogeneous, ranging from simple vesicles to complex compound structures, dynamically changing shape by fusions between Mm-containing and empty vesicles. LC3-Mm-vesicles could adopt elongated shapes during cell migration or alternate between spacious and compact morphologies. LC3-Mm-vesicles were also observed in cells reverse migrating from the infection site, indicating that the autophagy machinery fails to control infection before tissue dissemination.

Machine learning to determine the main factors affecting creep rates in laser powder bed fusion.

There is an increasing need for the use of additive manufacturing (AM) to produce improved critical application engineering components. However, the materials manufactured using AM perform well below their traditionally manufactured counterparts, particularly for creep and fatigue. Research has shown that this difference in performance is due to the complex relationships between AM process parameters which affect the material microstructure and consequently the mechanical performance as well. Therefore, it is necessary to understand the impact of different AM build parameters on the mechanical performance of parts. Machine learning (ML) models are able to find hidden relationships in data using iterative statistical analyses and have the potential to develop process-structure-property-performance relationships for manufacturing processes, including AM. The aim of this work is to apply ML techniques to materials testing data in order to understand the effect of AM process parameters on the creep rate of additively built nickel-based superalloy and to predict the creep rate of the material from these process parameters. In this work, the predictive capabilities of ML and its ability to develop process-structure-property relationships are applied to the creep properties of laser powder bed fused alloy 718. The input data for the ML model included the Laser Powder Bed Fusion (LPBF) build parameters used-build orientation, scan strategy and number of lasers-and geometrical material descriptors which were extracted from optical microscope porosity images using image analysis techniques. The ML model was used to predict the minimum creep rate of the Laser Powder Bed Fused alloy 718 samples, which had been creep tested at 650 ∘ C and 600 MPa. The ML model was also used to identify the most relevant material descriptors affecting the minimum creep rate of the material (determined by using an ensemble feature importance framework). The creep rate was accurately predicted with a percentage error of 1.40 % in the best case. The most important material descriptors were found to be part density, number of pores, build orientation and scan strategy. These findings show the applicability and potential of using ML to determine and predict the mechanical properties of materials fabricated via different manufacturing processes, and to find process-structure-property relationships in AM. This increases the readiness of AM for use in critical applications.

Cumulative inflammatory burden and obesity as determinants of insulin resistance in patients with established rheumatoid arthritis: cross-sectional study.

OBJECTIVES: To describe the prevalence of insulin resistance (IR) in patients with established rheumatoid arthritis (RA) and to analyse the contribution of cumulative inflammatory burden and other factors to its development. DESIGN: Observational cross-sectional study. PARTICIPANTS: Patients with RA and controls matched for age, sex and Body Mass Index. We excluded patients with diabetes. SETTINGS: Patients from an RA inception cohort at Hospital Regional Universitario de Málaga, Spain, were recruited between September 2016 and May 2018. PRIMARY AND SECONDARY OUTCOME MEASURES: IR was evaluated using the homeostasis model assessment for IR and beta-cell function and the quantitative insulin sensitivity check index. Other variables included the cumulative 28-Joint Disease Activity Score (DAS28) with C reactive protein (CRP) body composition and cytokines. Two logistic regression models were constructed to identify factors associated with IR in patients with RA. RESULTS: Eighty-nine patients with RA and 80 controls were included. The prevalence of IR was similar in both cases and controls. Inflammatory activity was controlled appropriately in patients during follow-up (mean DAS28 3.1 (0.8)). The presence of IR in patients with RA was associated with obesity (OR 6.01, 95% CI 1.9 to 8.7), higher cumulative DAS28-CRP values during follow-up (OR 2.8, 95% CI 1.3 to 6.0), and higher interleukin-1ß levels (OR 1.6, 95% CI 1.1 to 2.4). The second model showed that the risk of IR increased by 10% for each kilogram of excess body fat. CONCLUSION: In patients with well-controlled, established RA, IR is associated mainly with poorer control of inflammation from diagnosis and with obesity, specifically total fat mass.

Autophagy and Lc3-Associated Phagocytosis in Zebrafish Models of Bacterial Infections.

Modeling human infectious diseases using the early life stages of zebrafish provides unprecedented opportunities for visualizing and studying the interaction between pathogens and phagocytic cells of the innate immune system. Intracellular pathogens use phagocytes or other host cells, like gut epithelial cells, as a replication niche. The intracellular growth of these pathogens can be counteracted by host defense mechanisms that rely on the autophagy machinery. In recent years, zebrafish embryo infection models have provided in vivo evidence for the significance of the autophagic defenses and these models are now being used to explore autophagy as a therapeutic target. In line with studies in mammalian models, research in zebrafish has shown that selective autophagy mediated by ubiquitin receptors, such as p62, is important for host resistance against several bacterial pathogens, including Shigella flexneri, Mycobacterium marinum, and Staphylococcus aureus. Furthermore, an autophagy related process, Lc3-associated phagocytosis (LAP), proved host beneficial in the case of Salmonella Typhimurium infection but host detrimental in the case of S. aureus infection, where LAP delivers the pathogen to a replication niche. These studies provide valuable information for developing novel therapeutic strategies aimed at directing the autophagy machinery towards bacterial degradation.

CXCL12a/CXCR4b acts to retain neutrophils in caudal hematopoietic tissue and to antagonize recruitment to an injury site in the zebrafish larva.

Neutrophils are a major component of the innate immune response and the most abundant circulating cell type in humans and zebrafish. The CXCL12/CXCR4 ligand receptor pair plays a key role in neutrophil homeostasis, controlling definitive hematopoiesis and neutrophil release into circulation. Neutrophils overexpressing CXCR4 respond by migrating towards sources of CXCL12, which is abundant in hematopoietic tissues. However, the physiological role of CXCL12/CXCR4 signaling during inflammatory responses remains unknown. Here, we show that zebrafish mutants lacking functional CXCL12a or CXCR4b show disrupted granulopoiesis in the kidney and increased number of circulating neutrophils. Additionally, CXCL12a and CXCR4b mutants display exacerbated recruitment of neutrophils to wounds and not to infections, and migrating neutrophils to wounds show increased directionality. Our results show that CXCL12a/CXCR4b signaling antagonizes wound-induced inflammatory signals by retaining neutrophils in hematopoietic tissues as a part of a balance between both inflammatory and anti-inflammatory cues, whose dynamic levels control neutrophils complex migratory behavior.

Macrophage Recruitment Contributes to Regeneration of Mechanosensory Hair Cells in the Zebrafish Lateral Line.

In vertebrates, damage to mechanosensory hair cells elicits an inflammatory response, including rapid recruitment of macrophages and neutrophils. While hair cells in amniotes usually become permanently lost, they readily regenerate in lower vertebrates such as fish. Damage to hair cells of the fish lateral line is followed by inflammation and rapid regeneration; however the role of immune cells in this process remains unknown. Here, we show that recruited macrophages are required for normal regeneration of lateral line hair cells after copper damage. We found that genetic ablation or local ablation using clodronate liposomes of macrophages recruited to the site of injury, significantly delays hair cell regeneration. Neutrophils, on the other hand, are not needed for this process. We anticipate our results to be a starting point for a more detailed description of extrinsic signals important for regeneration of mechanosensory cells in vertebrates. J. Cell. Biochem. 117: 1880-1889, 2016. © 2016 Wiley Periodicals, Inc.

Factores de riesgo de fallecer en domicilio por neumonía de niños chilenos de estratos socioeconómicos bajos, Santiago de Chile: 1990-1994 / Risk factors for home deaths due to pneumonia among low socioeconomic level Chilean children, Santiago de Chile: 1990-1994

Background: Pneumonia is the main cause of late infant mortality in Chile. Over 60 percent of these deaths occur at home. The lack of hospital beds and the inadequate outpatient management are contributing factors. Aim: To assess risk factors for home deaths due to pneumonia in Chilean children. Patients and methods: The clinical and environmental histories of 53 (39 male) children that died due to pneumonia in their homes were analyzed. The cause of death was confirmed by necropsy with histopathological studies in all cases. These cases were compared with 88 control children of similar age, gender, socioeconomic status and living in the same geographical area of Metropolitan Santiago. Results: Fifty four percent of deceased children were of less than 3 months of age and only 3 cases and their controls were above1 year old. Identified risk factors for death were malnutrition with an odds ratio of 30.6 (CI 3.9-64.8, p< 0.001), low birth weight with an odds ratio of 5 (CI 1.8-14.1, p< 0.001), previous admissions to hospitals with an odds ratio of 5.79 (CI 2-17.1, p< 0.001), congenital malformations (mainly cardiac) with an odds ratio of 8.4 (CI 2-39.9, p= 0.001) and a history of bronchial obstruction with an odds ratio of 5.68 (p< 0.001). Identified maternal risk factors were smoking with an odds ratio of 4.13 (CI 1.6-10.7 p< 0.001) and being a teenager with an odds ratio of 4.3 (CI 1.7-11, p<0.001). Malnutrition, low birth weight, history of previous hospital admissions and having a teenager or smoker mother were considered as independent risk factors using a stepwise analysis. Conclusions: Chilean low income children have identifiable risk factors for death at their homes due to pneumonia, that can be preventively managed