119 research outputs found
Planetary formation in the Gamma-Cephei system
We numerically investigate under which conditions the planet detected at 2.1
AU of Gamma-Cephei could form through the core-accretion scenario despite the
perturbing presence of the highly eccentric companion star. We first show that
the initial stage of runaway accretion of kilometer-sized planetesimals is
possible within 2.5 AU from the central star only if large amounts of gas are
present. In this case, gaseous friction induces periastron alignment of the
orbits which reduces the otherwise high mutual impact velocities due to the
companion's secular perturbations. The following stage of mutual accretion of
large embryos is also modeled. According to our simulations, the giant impacts
among the embryos always lead to a core of 10 Mearth within 10 Myr, the average
lifetime of gaseous discs. However, the core always ends up within 1.5 AU from
the central star. Either the core grows more quickly in the inner region of the
disc, or it migrates inside by scattering the residual embryosComment: 8 pages, 12 figures to appear in Astronomy and Astrophysics (accepted
08/06/2004
Influence of the circumbinary disk gravity on planetesimal accumulation in the Kepler 16 system
Recent observations from NASA's Kepler mission detected the first planets in
circumbinary orbits. The question we try to answer is where these planets
formed in the circumbinary disk and how far inside they migrated to reach their
present location. We investigate the first and more delicate phase of planet
formation when planetesimals accumulate to form planetary embryos. We use the
hydrodynamical code FARGO to study the evolution of the disk and of a test
population of planetesimals embedded in it. With this hybrid
hydrodynamical--N--body code we can properly account for the gas drag force on
the planetesimals and for the gravitational force of the disk on them. The
numerical simulations show that the gravity of the eccentric disk on the
planetesimal swarm excites their eccentricities to values much larger than
those induced by the binary perturbations only within 10 AU from the stars.
Moreover, the disk gravity prevents a full alignment of the planetesimal
pericenters. Both these effects lead to large impact velocities, beyond the
critical value for erosion. Planetesimals accumulation in circumbinary disks
appears to be prevented close to the stellar pair by the gravitational
perturbations of the circumbinary disk. The observed planets possibly formed in
the outer regions of the disk and then migrated inside by tidal interaction
with the disk.Comment: Accepted for publication in A&
Chronic Morbilliviral Encephalitis in a Young Striped Dolphin from Italy
A young male striped dolphin (Stenella coeruleoalba) found stranded in November 2009 was affected by a chronic non-suppurative encephalitis, with prominent mononuclear cell perivascular cuffs, neuronal degeneration, microgliosis, neuronophagia and occasional presence of multinucleate syncytia. Immunohistochemical and biomolecular investigations for Morbillivirus were positive exclusively from the brain, but not from the cerebellum nor from any other tissue, with morbilliviral antigen being detected in neurons and astrocytes. A low neutralizing antibody titer (1:10) against Morbillivirus (CDV) was also found, with no simultaneous presence of anti-Brucella antibodies.
The main reason why the present case appears to be of interest is provided by its peculiar neuro-histopathologic, immunohistochemical and biomolecular features, with Morbillivirus antigenic and genomic positivity being exclusively confined to the brain of this dolphin, which may have developed a transplacentally-acquired infection
A New Multilocus Sequence Typing Scheme and Its Application for the Characterization of Photobacterium damselae subsp. damselae Associated with Mortality in Cetaceans
Photobacterium damselae subsp. damselae (PDD) is a known pathogen of fish, humans and marine mammals. In this study, a Multilocus Sequence Typing (MLST) scheme based on six housekeeping genes (glp, gyrB, metG, pnt, pyrC and toxR) was developed to better understand the PDD population structure and used to type 73 PDD isolates from cetaceans, mainly striped dolphins (Stenella coeruleoalba) involved in mortality episodes, and from a few marine chelonians. Five reference ATCC strains were also included in the study. Typing allowed the discrimination of groups of PDD strains isolated from different host species, at different times and from different geographic areas, suggesting that a clonal PDD group may have spread in the Tyrrhenian sea at the time of an Unusual Mortality Event (UME) among cetaceans, mainly striped dolphins, occurred in early 2013 along the Italian western coasts
Dog filariosis in the Lazio region (Central Italy): first report on the presence of Dirofilaria repens
BACKGROUND: Epidemiological investigations were carried out in the Lazio Region to assess the status of canine filariosis and to evaluate the actual risk for veterinary and medical public health. METHODS: Since August 2001 to June 2003, a total of 972 canine blood samples, collected in public kennels and from private owners animals of the 5 Provinces of the Region, were tested. The presence of filarial parasites was evaluated by microscopy and bio-molecular techniques; the species identification was performed by means of the same diagnostic tools. RESULTS: A total of 17/972 (1.75%; 95%CI 1.06%â2.85%) blood samples were parasitized by D. repens,13 out them drawn by dogs resident in the Province of Roma, and 4 in the other provinces. Multivariate analysis was performed in order to evaluate the association between filariosis and risk factors. The origin from coastal territories seems to be a significant risk factor to acquire the infection. CONCLUSION: This is the first report of canine filariosis in the Lazio Region, where D. repens was before reported only in foxes. The risk of human zoonotic infection is stressed, and the absence of other filarial species is discusse
The Genetic Landscape and Epidemiology of Phenylketonuria
Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]â1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066â11G>A (IVS10â11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066â11G>A];[1066â11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.Fil: Hillert, Alicia. No especifĂca;Fil: Anikster, Yair. No especifĂca;Fil: Belanger Quintana, Amaya. No especifĂca;Fil: Burlina, Alberto. No especifĂca;Fil: Burton, Barbara K.. No especifĂca;Fil: Carducci, Carla. No especifĂca;Fil: Chiesa, Ana Elena. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. Centro de Investigaciones EndocrinolĂłgicas "Dr. CĂ©sar Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones EndocrinolĂłgicas "Dr. CĂ©sar Bergada". FundaciĂłn de EndocrinologĂa Infantil. Centro de Investigaciones EndocrinolĂłgicas "Dr. CĂ©sar Bergada"; ArgentinaFil: Christodoulou, John. No especifĂca;Fil: Dordevic, Maja. No especifĂca;Fil: Desviat, Lourdes R.. No especifĂca;Fil: Eliyahu, Aviva. No especifĂca;Fil: Evers, Roeland A.F.. No especifĂca;Fil: Fajkusova, Lena. No especifĂca;Fil: Feillet, Francois. No especifĂca;Fil: Bonfim Freitas, Pedro E.. No especifĂca;Fil: Gizewska, MarĂa. No especifĂca;Fil: Gundorova, Polina. No especifĂca;Fil: Karall, Daniela. No especifĂca;Fil: Kneller, Katya. No especifĂca;Fil: Kutsev, Sergey I.. No especifĂca;Fil: Leuzzi, Vincenzo. No especifĂca;Fil: Levy, Harvey L.. No especifĂca;Fil: Lichter Koneck, Uta. No especifĂca;Fil: Muntau, Ania C.. No especifĂca;Fil: Namour, Fares. No especifĂca;Fil: Oltarzewsk, Mariusz. No especifĂca;Fil: Paras, Andrea. No especifĂca;Fil: Perez, BelĂ©n. No especifĂca;Fil: Polak, Emil. No especifĂca;Fil: Polyakov, Alexander V.. No especifĂca;Fil: Porta, Francesco. No especifĂca;Fil: Rohrbach, Marianne. No especifĂca;Fil: Scholl BĂŒrgi, Sabine. No especifĂca;Fil: SpĂ©cola, Norma. No especifĂca;Fil: Stojiljkovic, Maja. No especifĂca;Fil: Shen, Nan. No especifĂca;Fil: Santana da Silva, Luiz C.. No especifĂca;Fil: Skouma, Anastasia. No especifĂca;Fil: van Spronsen, Francjan. No especifĂca;Fil: Stoppioni, Vera. No especifĂca;Fil: Thöny, Beat. No especifĂca;Fil: Trefz, Friedrich K.. No especifĂca;Fil: Vockley, Jerry. No especifĂca;Fil: Yu, Youngguo. No especifĂca;Fil: Zschocke, Johannes. No especifĂca;Fil: Hoffmann, Georg F.. No especifĂca;Fil: Garbade, Sven F.. No especifĂca;Fil: Blau, Nenad. No especifĂca
The Genetic Landscape and Epidemiology of Phenylketonuria
Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]-1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A gt G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C gt T (p.Arg408Trp) (22.2%), c.1066-11G gt A (IVS10-11G gt A) (6.4%), and c.782G gt A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G gt A];[1066-11G gt A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome
Oligomeric Coiled-Coil Adhesin YadA Is a Double-Edged Sword
Yersinia adhesin A (YadA) is an essential virulence factor for the food-borne pathogens Yersinia enterocolitica and Yersinia pseudotuberculosis. Suprisingly, it is a pseudogene in Yersinia pestis. Even more intriguing, the introduction of a functional yadA gene in Y. pestis EV76 was shown to correlate with a decrease in virulence in a mouse model. Here, we report that wild type (wt) Y. enterocolitica E40, as well as YadA-deprived E40 induced the synthesis of neutrophil extracellular traps (NETs) upon contact with neutrophils, but only YadA-expressing Y. enterocolitica adhered to NETs and were killed. As binding seemed to be a prerequisite for killing, we searched for YadA-binding substrates and detected the presence of collagen within NETs. E40 bacteria expressing V98D,N99A mutant YadA with a severely reduced ability to bind collagen were found to be more resistant to killing, suggesting that collagen binding contributes significantly to sensitivity to NETs. Wt Y. pestis EV76 were resistant to killing by NETs, while recombinant EV76 expressing YadA from either Y. pseudotuberculosis or Y. enterocolitica were sensitive to killing by NETs, outlining the importance of YadA for susceptibility to NET-dependent killing. Recombinant EV76 endowed with YadA from Y. enterocolitica were also less virulent for the mouse than wt EV76, as shown before. In addition, EV76 carrying wt YadA were less virulent for the mouse than EV76 expressing YadAV98D,N99A. The observation that YadA makes Yersinia sensitive to NETs provides an explanation as for why evolution selected for the inactivation of yadA in the flea-borne Y. pestis and clarifies an old enigma. Since YadA imposes the same cost to the food-borne Yersinia but was nevertheless conserved by evolution, this observation also illustrates the duality of some virulence functions
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