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Farber G, Hurtado R, Loh S, Monette S, Mtui J, Kopan R, Quaggin S, Meyer-Schwesinger C, Herzlinger D, Scott RP, Blobel CP
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Glomerular endothelial cell maturation depends on ADAM10, a key regulator of Notch signaling

ANGIOGENESIS 2018 MAY; 21(2):335-347
The principal function of glomeruli is to filter blood through a highly specialized filtration barrier consisting of a fenestrated endothelium, the glomerular basement membrane and podocyte foot processes. Previous studies have uncovered a crucial role of endothelial a disintegrin and metalloprotease 10 (ADAM10) and Notch signaling in the development of glomeruli, yet the resulting defects have not been further characterized nor understood in the context of kidney development. Here, we used several different experimental approaches to analyze the kidneys and glomeruli from mice lacking ADAM10 in endothelial cells (A10 Delta EC mice). Scanning electron microscopy of glomerular casts demonstrated enlarged vascular diameter and increased intussusceptive events in A10 Delta EC glomeruli compared to controls. Consistent with these findings, genes known to regulate vessel caliber (Apln, AplnR and Vegfr3) are significantly upregulated in A10 Delta EC glomeruli. Moreover, transmission electron microscopy revealed the persistence of diaphragms in the fenestrae of A10 Delta EC glomerular endothelial cells, which was corroborated by the elevated expression of the protein PLVAP/PV-1, an integral component of fenestral diaphragms. Analysis of gross renal vasculature by light sheet microscopy showed no major alteration of the branching pattern, indicating a localized importance of ADAM10 in the glomerular endothelium. Since intussusceptions and fenestrae with diaphragms are normally found in developing, but not mature glomeruli, our results provide the first evidence for a crucial role of endothelial ADAM10, a key regulator of Notch signaling, in promoting the development and maturation of the glomerular vasculature.
Mitchell MR, Leibler S
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Elastic strain and twist analysis of protein structural data and allostery of the transmembrane channel KcsA

PHYSICAL BIOLOGY 2018 MAY; 15(3):? Article 036004
The abundance of available static protein structural data makes the more effective analysis and interpretation of this data a valuable tool to supplement the experimental study of protein mechanics. Structural displacements can be difficult to analyze and interpret. Previously, we showed that strains provide a more natural and interpretable representation of protein deformations, revealing mechanical coupling between spatially distinct sites of allosteric proteins. Here, we demonstrate that other transformations of displacements yield additional insights. We calculate the divergence and curl of deformations of the transmembrane channel KcsA. Additionally, we introduce quantities analogous to bend, splay, and twist deformation energies of nematic liquid crystals. These transformations enable the decomposition of displacements into different modes of deformation, helping to characterize the type of deformation a protein undergoes. We apply these calculations to study the filter and gating regions of KcsA. We observe a continuous path of rotational deformations physically coupling these two regions, and, we propose, underlying the allosteric interaction between these regions. Bend, splay, and twist distinguish KcsA gate opening, filter opening, and filter-gate coupling, respectively. In general, physically meaningful representations of deformations (like strain, curl, bend, splay, and twist) can make testable predictions and yield insights into protein mechanics, augmenting experimental methods and more fully exploiting available structural data.
Hammond WJ, Lalazar G, Saltsman JA, Farber BA, Danzer E, Sherpa TC, Banda CD, Andolina JR, Karimi S, Brennan CW, Torbenson MS, La Quaglia MP, Simon SM
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Intracranial metastasis in fibrolamellar hepatocellular carcinoma

PEDIATRIC BLOOD & CANCER 2018 APR; 65(4):? Article e26919
Fibrolamellar hepatocellular carcinoma (FLHCC) is a rare liver malignancy in adolescents and young adults. Surgery is the mainstay of therapy for primary and metastatic disease. Most patients relapse, with development of both local and distant metastases. Brain metastases from solid tumors are rare in the pediatric and young adult population. Here, we document three patients with brain metastases from FLHCC, confirmed by histology and molecular characterization of the chimeric fusion DNAJB1-PRKACA, each necessitating neurosurgical intervention. These observations highlight the ability of FLHCC to metastasize to the brain and suggest the need for surveillance neuroimaging for patients with advanced-stage disease.
Peyrottes A, Mariage D, Baque P, Massalou D
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Pancreaticoduodenal artery aneurysms due to median arcuate ligament syndrome: what we need to know

Median arcuate ligament (MAL) syndrome is a rare and poorly known cause of abdominal pain. MAL narrows the celiac artery (CA), resulting in true distal aneurysms, including pancreaticoduodenal artery (PDA) aneurysms. These aneurysms often have an aggressive course, as rupture can result in hemorrhagic shock. CT scan appears to be the most effective investigation for the diagnosis of PDA aneurysms and may reveal possible celiac artery compression. In this series, we describe four cases of PDA aneurysm: two ruptured aneurysms treated by an endovascular procedure and two non-ruptured aneurysms treated by surgery. It was also decided to treat CA stenosis in three of the four patients based on the clinical presentation (ruptured or non-ruptured) and the presence of peripancreatic collateral vessels on imaging. This strategy contrasts with the approach commonly reported in the literature, in which MAL section is mandatory due to the high risk of ischemia rather than the potential risk of recurrent aneurysm. Medical teams should be aware of this disease to improve diagnosis and patient management.
Warejko JK, Schueler M, Vivante A, Tan WZ, Daga A, Lawson JA, Braun DA, Shril S, Amann K, Somers MJG, Rodig NM, Baum MA, Daouk G, Traum AZ, Kim HB, Vakili K, Porras D, Lock J, Rivkin MJ, Chaudry G, Smoot LB, Singh MN, Smith ER, Mane SM, Lifton RP, Stein DR, Ferguson MA, Hildebrandt F
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Whole Exome Sequencing Reveals a Monogenic Cause of Disease in approximate to 43% of 35 Families With Midaortic Syndrome

HYPERTENSION 2018 APR; 71(4):691-699
Midaortic syndrome (MAS) is a rare cause of severe childhood hypertension characterized by narrowing of the abdominal aorta in children and is associated with extensive vascular disease. It may occur as part of a genetic syndrome, such as neurofibromatosis, or as consequence of a pathological inflammatory disease. However, most cases are considered idiopathic. We hypothesized that in a high percentage of these patients, a monogenic cause of disease may be detected by evaluating whole exome sequencing data for mutations in 1 of 38 candidate genes previously described to cause vasculopathy. We studied a cohort of 36 individuals from 35 different families with MAS by exome sequencing. In 15 of 35 families (42.9%), we detected likely causal dominant mutations. In 15 of 35 (42.9%) families with MAS, whole exome sequencing revealed a mutation in one of the genes previously associated with vascular disease (NF1, JAG1, ELN, GATA6, and RNF213). Ten of the 15 mutations have not previously been reported. This is the first report of ELN, RNF213, or GATA6 mutations in individuals with MAS. Mutations were detected in NF1 (6/15 families), JAG1 (4/15 families), ELN (3/15 families), and one family each for GATA6 and RNF213. Eight individuals had syndromic disease and 7 individuals had isolated MAS. Whole exome sequencing can provide conclusive molecular genetic diagnosis in a high fraction of individuals with syndromic or isolated MAS. Establishing an etiologic diagnosis may reveal genotype/phenotype correlations for MAS in the future and should, therefore, be performed routinely in MAS.
Butler IA, Peters MK, Kronauer DJC
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Low levels of hybridization in two species of African driver ants

Hybridization in ants can have consequences different from those observed in most other species, with many of the potential deleterious effects being mitigated due to haplodiploidy and eusociality. In some species where colonies are either headed by multiple queens or single queens that mate with many males, hybridization is associated with genetic caste determination, where hybrids develop into workers and purebred individuals develop into queens. A previous study suggested that hybridization occurs between two Dorylus army ant species with multiply mated queens. However, the extent and exact pattern of hybridization have remained unclear, and its possible effect on caste determination has not been investigated. In this study, we aimed to determine the extent and direction of hybridization by measuring how frequently hybrids occur in colonies of both species, and to investigate the possibility of genetic caste determination. We show that hybridization is bidirectional and occurs at equal rates in both species. Hybrid workers make up only 1-2% of the population, and successful interspecific matings represent approximately 2% of all matings in both species. This shows that, although interspecific matings that give rise to worker offspring occur regularly, they are much rarer than intraspecific mating. Finally, we find no evidence of an association between hybridization and genetic caste determination in this population. This means that genetic caste determination is not a necessary outcome of hybridization in ants, even in species where queens mate with multiple males.
Hover BM, Kim SH, Katz M, Charlop-Powers Z, Owen JG, Ternei MA, Maniko J, Estrela AB, Molina H, Park S, Perlin DS, Brady SF
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Culture-independent discovery of the malacidins as calcium-dependent antibiotics with activity against multidrug-resistant Gram-positive pathogens

NATURE MICROBIOLOGY 2018 APR; 3(4):415-422
Despite the wide availability of antibiotics, infectious diseases remain a leading cause of death worldwide(1). In the absence of new therapies, mortality rates due to untreatable infections are predicted to rise more than tenfold by 2050. Natural products (NPs) made by cultured bacteria have been a major source of clinically useful antibiotics. In spite of decades of productivity, the use of bacteria in the search for new antibiotics was largely abandoned due to high rediscovery rates(2,3). As only a fraction of bacterial diversity is regularly cultivated in the laboratory and just a fraction of the chemistries encoded by cultured bacteria are detected in fermentation experiments, most bacterial NPs remain hidden in the global microbiome. In an effort to access these hidden NPs, we have developed a culture-independent NP discovery platform that involves sequencing, bioinformatic analysis and heterologous expression of biosynthetic gene clusters captured on DNA extracted from environmental samples. Here, we describe the application of this platform to the discovery of the malacidins, a distinctive class of antibiotics that are commonly encoded in soil microbiomes but have never been reported in culture-based NP discovery efforts. The malacidins are active against multidrug-resistant pathogens, sterilize methicillin-resistant Staphylococcus aureus skin infections in an animal wound model and did not select for resistance under our laboratory conditions.
Kafkafi N, Agassi J, Chesler EJ, Crabbe JC, Crusio WE, Eilam D, Gerlai R, Goiani I, Gomez-Marin A, Heller R, Iraqi F, Jaljuli I, Karp NA, Morgan H, Nicholson G, Pfaff DW, Richter SH, Stark PB, Stiedl O, Stodden V, Tarantino LM, Tucci V, Valdar W, Williams RW, Wurbel H, Benjamini Y
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Reproducibility and replicability of rodent phenotyping in preclinical studies

The scientific community is increasingly concerned with the proportion of published "discoveries" that are not replicated in subsequent studies. The field of rodent behavioral phenotyping was one of the first to raise this concern, and to relate it to other methodological issues: the complex interaction between genotype and environment; the definitions of behavioral constructs; and the use of laboratory mice and rats as model species for investigating human health and disease mechanisms. In January 2015, researchers from various disciplines gathered at Tel Aviv University to discuss these issues. The general consensus was that the issue is prevalent and of concern, and should be addressed at the statistical, methodological and policy levels, but is not so severe as to call into question the validity and the usefulness of model organisms as a whole. Well-organized community efforts, coupled with improved data and metadata sharing, have a key role in identifying specific problems and promoting effective solutions. Replicability is closely related to validity, may affect generalizability and translation of findings, and has important ethical implications.
Hegele RA
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Doolittle WF, Finlay BB, Fischetti VA, Kaufmann SHE, Sasakawa C, Sattentau Q
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How Has Microbiology Changed over the Past 25 Years?

TRENDS IN MICROBIOLOGY 2018 APR; 26(4):246-250
In honor of our 25th anniversary, we wanted to take a look back over these past 25 years. Here, we asked members of our editorial board to reflect on the changes that have occurred within the field of microbiology during this time.