666 research outputs found
Australia's Oldest Marsupial Fossils and their Biogeographical Implications
Background: We describe new cranial and post-cranial marsupial fossils from the early Eocene Tingamarra Local Fauna in Australia and refer them to Djarthia murgonensis, which was previously known only from fragmentary dental remains. Methodology/Principal Findings: The new material indicates that Djarthia is a member of Australidelphia, a pan-Gondwanan clade comprising all extant Australian marsupials together with the South American microbiotheres. Djarthia is therefore the oldest known crown-group marsupial anywhere in the world that is represented by dental, cranial and postcranial remains, and the oldest known Australian marsupial by 30 million years. It is also the most plesiomorphic known australidelphian, and phylogenetic analyses place it outside all other Australian marsupials. Conclusions/Significance: As the most plesiomorphic and oldest unequivocal australidelphian, Djarthia may approximate the ancestral morphotype of the Australian marsupial radiation and suggests that the South American microbiotheres may be the result of back-dispersal from eastern Gondwana, which is the reverse of prevailing hypotheses
The skull of Epidolops ameghinoi from the early Eocene Itaboraí fauna, southeastern Brazil, and the affinities of the extinct marsupialiform order Polydolopimorphia
The skull of the polydolopimorphian marsupialiform Epidolops ameghinoi is described
in detail for the first time, based on a single well-preserved cranium and associated left
and right dentaries plus additional craniodental fragments, all from the early Eocene
(53-50 million year old) Itaboraí fauna in southeastern Brazil. Notable craniodental
features of E. ameghinoi include absence of a masseteric process, very small
maxillopalatine fenestrae, a prominent pterygoid fossa enclosed laterally by a
prominent ectopterygoid crest, an absent or tiny transverse canal foramen, a simple,
planar glenoid fossa, and a postglenoid foramen that is immediately posterior to the
postglenoid process. Most strikingly, the floor of the hypotympanic sinus was
apparently unossified, a feature found in several stem marsupials but absent in all
known crown marsupials. "Type II" marsupialiform petrosals previously described from
Itaboraí plausibly belong to E. ameghinoi; in published phylogenetic analyses, these
petrosals fell outside (crown-clade) Marsupialia. "IMG VII" tarsals previously referred to
E. ameghinoi do not share obvious synapomorphies with any crown marsupial clade,
nor do they resemble those of the only other putative polydolopimorphians represented
by tarsal remains, namely the argyrolagids. Most studies have placed
Polydolopimorphia within Marsupialia, related to either Paucituberculata, or to
Microbiotheria and Diprotodontia. However, diprotodonty almost certainly evolved
independently in polydolopimorphians, paucituberculatans and diprotodontians, and
Epidolops does not share obvious synapomorphies with any marsupial order.
Epidolops is dentally specialized, but several morphological features appear to be
more plesiomorphic than any crown marsupial. It seems likely Epidolops that falls
outside Marsupialia, as do morphologically similar forms such as Bonapartherium and
polydolopids. Argyrolagids differ markedly in their known morphology from Epidolops
but share some potential apomorphies with paucituberculatans. It is proposed that
Polydolopimorphia as currently recognised is polyphyletic, and that argyrolagids (and
possibly other taxa currently included in Argyrolagoidea, such as groeberiids and
patagoniids) are members of Paucituberculata. This hypothesis is supported by
Bayesian non-clock phylogenetic analyses of a total evidence matrix comprising DNA
sequence data from five nuclear protein-coding genes, indels, retroposon insertions
and morphological characters: Epidolops falls outside Marsupialia, whereas
argyrolagids form a clade with the paucituberculatans Caenolestes and Palaeothentes,
regardless of whether the Type II petrosals and IMG VII tarsals are used to score
characters for Epidolops or not. There is no clear evidence for the presence of crown
marsupials at Itaboraí, and it is possible that the origin and early evolution of
Marsupialia was restricted to the "Austral Kingdom" (southern South America,
Antarctica, and Australia)
An exceptionally well-preserved skeleton of Palaeothentes from the Early Miocene of Patagonia, Argentina: new insights into the anatomy of extinct paucituberculatan marsupials
International audienc
Translational Stroke Research Using a Rabbit Embolic Stroke Model: A Correlative Analysis Hypothesis for Novel Therapy Development
Alteplase (tissue plasminogen activator, tPA) is currently the only FDA-approved treatment that can be given to acute ischemic stroke (AIS) patients if patients present within 3 h of an ischemic stroke. After 14 years of alteplase clinical research, evidence now suggests that the therapeutic treatment window can be expanded 4.5 h, but this is not formally approved by the FDA. Even though there remains a significant risk of intracerebral hemorrhage associated with alteplase administration, there is an increased chance of favorable outcome with tPA treatment. Over the last 30 years, the use of preclinical models has assisted with the search for new effective treatments for stroke, but there has been difficulty with the translation of efficacy from animals to humans. Current research focuses on the development of new and potentially useful thrombolytics, neuroprotective agents, and devices which are also being tested for efficacy in preclinical and clinical trials. One model in particular, the rabbit small clot embolic stroke model (RSCEM) which was developed to test tPA for efficacy, remains the only preclinical model used to gain FDA approval of a therapeutic for stroke. Correlative analyses from existing preclinical translational studies and clinical trials indicate that there is a therapeutic window ratio (ARR) of 2.43-3 between the RSCEM and AIS patients. In conclusion, the RSCEM can be used as an effective translational tool to gauge the clinical potential of new treatments
Internal carotid artery stenosis: comparison of duplex scan and magnetic resonance angiography with digital subtraction angiography
Micromorphological and hardness analyses of human and bovine sclerotic dentin: a comparative study
Influência da marca do condicionador ácido na resistência de união da resina composta à dentina
New Copy Number Variations in Schizophrenia
Genome-wide screenings for copy number variations (CNVs) in patients with schizophrenia have demonstrated the presence of several CNVs that increase the risk of developing the disease and a growing number of large rare CNVs; the contribution of these rare CNVs to schizophrenia remains unknown. Using Affymetrix 6.0 arrays, we undertook a systematic search for CNVs in 172 patients with schizophrenia and 160 healthy controls, all of Italian origin, with the aim of confirming previously identified loci and identifying novel schizophrenia susceptibility genes. We found five patients with a CNV occurring in one of the regions most convincingly implicated as risk factors for schizophrenia: NRXN1 and the 16p13.1 regions were found to be deleted in single patients and 15q11.2 in 2 patients, whereas the 15q13.3 region was duplicated in one patient. Furthermore, we found three distinct patients with CNVs in 2q12.2, 3q29 and 17p12 loci, respectively. These loci were previously reported to be deleted or duplicated in patients with schizophrenia but were never formally associated with the disease. We found 5 large CNVs (>900 kb) in 4q32, 5q14.3, 8q23.3, 11q25 and 17q12 in five different patients that could include some new candidate schizophrenia susceptibility genes. In conclusion, the identification of previously reported CNVs and of new, rare, large CNVs further supports a model of schizophrenia that includes the effect of multiple, rare, highly penetrant variants
Changes in Plasma Membrane Surface Potential of PC12 Cells as Measured by Kelvin Probe Force Microscopy
The plasma membrane of a cell not only works as a physical barrier but also mediates the signal relay between the extracellular milieu and the cell interior. Various stimulants may cause the redistribution of molecules, like lipids, proteins, and polysaccharides, on the plasma membrane and change the surface potential (Φs). In this study, the Φss of PC12 cell plasma membranes were measured by atomic force microscopy in Kelvin probe mode (KPFM). The skewness values of the Φss distribution histogram were found to be mostly negative, and the incorporation of negatively charged phosphatidylserine shifted the average skewness values to positive. After being treated with H2O2, dopamine, or Zn2+, phosphatidylserine was found to be translocated to the membrane outer leaflet and the averaged skewness values were changed to positive values. These results demonstrated that KPFM can be used to monitor cell physiology status in response to various stimulants with high spatial resolution
Zinc and silica are active components to efficiently treat in vitro simulated eroded dentin.
Objectives: Biomaterials for treating dentin hypersensitivity and dentin wear were
evaluated, to efficiently occlude the dentinal tubules and to increase dentin resistance to
abrasion. Materials and Methods: 24 dentin surfaces were treated with EDTA to expose
dentinal tubules, and were: 1) non-brushed, 2) brushed with distilled water, or with pastes
containing 3) Monetite, 4) Brushite, 5) Zn-Monetite, 6) Zn-Brushite, 7) Silica-Brushite
and 8) NovaMin®. Topography, nanomechanical and chemical analysis were assessed on
dentin surfaces (n=3) after artificial saliva immersion for 24 h, and after citric acid
challenge. 21 further dentin specimens were created to evaluate dentin permeability after
brushing, saliva storage and acid application (n=3). ANOVA, Student-Newman-Keuls
(p<0.05) and Student t-test (p<0.001) were used. Results: Particles containing major
proportion of silica attained intratubular occlusion by carbonate crystals (Raman
carbonate peak heights: 15.17 and 19.24 au; complex modulus: 110 and 140 GPa, at
intratubular dentin). When brushing with pastes containing higher proportion of silica or
zinc, phosphate calcium compounds were encountered into tubules and over dentin
surfaces (Raman intratubular phosphate peak heights: 49 to 70 au, and at the intertubular
dentin: 78 to 92). The formed carbonated apatite and calcium phosphate layer were
resistant to citric acid application. Zinc compounds drastically increased tubule occlusion,
decreased dentin permeability (up to 30%) and augmented mechanical properties at the
intertubular dentin (90-130 GPa), it was maintained after acid challenging. Conclusions:
Zinc-containing pastes occluded dentinal tubules and improved dentin mechanical
properties. Clinical Relevance: Using zinc as an active component to treat eroded dentin
is encouraged.Projects RTC-2014-1731-1 and MAT2014-52036-P
supported by the Ministry of Economy and Competitiveness and European Regional
Development Fund
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