Breakdown of the adiabatic Born-Oppenheimer approximation in graphene

The adiabatic Born-Oppenheimer approximation (ABO) has been the standard ansatz to describe the interaction between electrons and nuclei since the early days of quantum mechanics. ABO assumes that the lighter electrons adjust adiabatically to the motion of the heavier nuclei, remaining at any time in their instantaneous ground state. ABO is well justified when the energy gap between ground and excited electronic states is larger than the energy scale of the nuclear motion. In metals, the gap is zero and phenomena beyond ABO (such as phonon-mediated superconductivity or phonon-induced renormalization of the electronic properties) occur. The use of ABO to describe lattice motion in metals is, therefore, questionable. In spite of this, ABO has proved effective for the accurate determination of chemical reactions, molecular dynamics and phonon frequencies in a wide range of metallic systems. Here, we show that ABO fails in graphene. Graphene, recently discovered in the free state, is a zero-bandgap semiconductor that becomes a metal if the Fermi energy is tuned applying a gate voltage, Vg. This induces a stiffening of the Raman G peak that cannot be described within ABO.     

VEGF-C receptor binding and pattern of expression with VEGFR-3 suggests a role in lymphatic vascular development

The vascular endothelial growth factor family has recently been expanded by the isolation of two new VEGF-related factors, VEGF-B and VEGF-C. The physiological functions of these factors are largely unknown. Here we report the cloning and characterization of mouse VEGF-C, which is produced as a disulfide-linked dimer of 415 amino acid residue polypeptides, sharing an 85% identity with the human VEGF-C amino acid sequence. The recombinant mouse VEGF-C protein was secreted from transfected cells as VEGFR-3 (Flt4) binding polypeptides of 30-32x10(3) Mr and 22-23x10(3) Mr which preferentially stimulated the autophosphorylation of VEGFR-3 in comparison with VEGFR-2 (KDR). In in situ hybridization, mouse VEGF-C mRNA expression was detected in mesenchymal cells of postimplantation mouse embryos, particularly in the regions where the lymphatic vessels undergo sprouting from embryonic veins, such as the perimetanephric, axillary and jugular regions. In addition, the developing mesenterium, which is rich in lymphatic vessels, showed strong VEGF-C expression. VEGF-C was also highly expressed in adult mouse lung, heart and kidney, where VEGFR-3 was also prominent. The pattern of expression of VEGF-C in relation to its major receptor VEGFR-3 during the sprouting of the lymphatic endothelium in embryos suggests a paracrine mode of action and that one of the functions of VEGF-C may be in the regulation of angiogenesis of the lymphatic vasculature.     

Treatment of a newly established transgenic model of chronic arthritis with nondepleting anti-CD4 monoclonal antibody

We established a novel animal model for rheumatoid arthritis (RA) by following backcrossing to DBA/1 of (SWR/J x DBA/1)F1 TCR-beta Tg mice, previously reported to be highly susceptible to collagen-induced arthritis. These mice evolved, upon collagen type II immunization, into a chronic arthritis that histopathologically resembles RA. The availability of such a model prompted us to study the role of CD4+ T cells throughout the evolution of disease. Here, we show that administration of nondepleting anti-CD4 not only prevented the evolution of disease but also treated established arthritis. Moreover, functional analyses of T cells isolated from anti-CD4-treated mice demonstrated that the mechanism of protection is not achieved by suppression of the Th1 population but is mediated by induction of collagen type II-specific T cell anergy. Our study suggests that: 1) CD4+ T cells have a fundamental role both in the induction and in the perpetuation of disease; 2) targeting T cells may be an appropriate therapeutic option; and 3) a suitable and well-balanced anti-CD4 treatment may be a valid approach to the control of RA.     

Gluten sensitivity in the rectal mucosa of first-degree relatives of celiac disease patients

BACKGROUND/AIMS: Rectal gluten challenge is a simple, sensitive, and specific test of mucosal gluten sensitivity. Our aims in this study were to evaluate gluten sensitivity in a group of relatives of celiac patients and to compare these findings with those obtained on small bowel histology, celiac disease-related serology, and HLA typing. METHODS: A 4-h rectal gluten challenge was performed with 6 g of crude gluten in saline solution in 29 first-degree relatives, 20 well-diagnosed celiac patients, and 10 subjects in whom celiac disease had been excluded. The number of intraepithelial lymphocytes in pre- and postchallenge frozen rectal biopsies (pan T-cell immunocytochemistry) was quantified by computerized image analysis. RESULTS: The intraepithelial lymphocyte response after gluten instillation was significantly higher in celiac disease patients (median, 126% increase above the baseline count; 95% confidence interval: 61-213%) compared with control subjects (median, -5%; 95% confidence interval: -29-5%). Using a cut-off of 20% change in intraepithelial lymphocyte count, 14 relatives (48%) showed a celiac-like response. Two of these subjects had partial villous atrophy and increased lymphocyte counts in the small bowel mucosa. One of them also exhibited a positive celiac disease-related serology and the typical celiac human lymphocyte antibody (HLA) DQ2. The remaining 12, and all those relatives with a negative challenge, had normal small bowel mucosa and were negative for antigliadin and endomysial antibodies. The characteristic celiac HLA (DQA1 0501 DQB1 0201 heterodimer) was identified in five relatives with positive challenge (including the patient with more severe mucosal atrophy) but was also present in eight relatives with no evidence of gluten sensitivity in the rectal mucosa. CONCLUSIONS: Our study characterizes a subgroup of relatives of celiac patients who show mucosal evidence of sensitization after local instillation of gluten in the rectum but who have no other features of celiac disease.     

Self‐Assembled pH‐Sensitive Fluoromagnetic Nanotubes as Archetype System for Multimodal Imaging of Brain Cancer

Fluoromagnetic systems are recognized as an emerging class of materials with great potential in the biomedical field. Here, it is shown how to fabricate fluoromagnetic nanotubes that can serve as multimodal probes for the imaging and targeting of brain cancer. An ionic self‐assembly strategy is used to functionalize the surface of synthetic chrysotile nanotubes with pH‐sensitive fluorescent chromophores and ferromagnetic nanoparticles. The acquired magnetic properties permit their use as contrast agent for magnetic resonance imaging, and enable the tracking of tumor cell migration and infiltration responsible for metastatic growth and disease recurrence. Their organic component, changing its fluorescence attitude as a function of local pH, targets the cancer distinctive acidity, and allows localizing and monitoring the tumor occurrence and progression by mapping the acidic spatial distribution within biopsy tissues. The fluoromagnetic properties of nanotubes are preserved from the in vitro to the in vivo condition and they show the ability to migrate across the blood brain barrier, thus spontaneously reaching the brain tumor after injection. The simplicity of the synthesis route of these geomimetic nanomaterials combined with their demonstrated affinity with the in vivo condition strongly highlights their potential for developing effective functional materials for multimodal theranostics of brain cancer.     

PLCTOOLS: Graph Transformation Meets PLC Design

This paper presents PLCTOOLS, a formal environment for designing and simulating programmable controllers. Control models are specified with IEC FED (Function Block Diagram), and translated into functionally equivalent HLTPNs (High-Level Timed Petri Nets), through MetaEnv, for analysis and simulation and obtained results are presented in terms of suitable animations of FED blocks.The peculiarity with FBD is that it does not come with a fixed set of syntactic elements; it allows users to add as many new blocks as they want. Consequently, each time users want to add a new FBD block with PLCTOOLS, they must provide the concrete syntax, to add it to the library of available blocks, but also the associated HLTPN, to allow MetaEnv to build the formal representation.