Modelling photosystem I as a complex interacting network

In this paper, we model the excitation energy transfer (EET) of photosystem I (PSI) of the common pea plant Pisum sativum as a complex interacting network. The magnitude of the link energy transfer between nodes/chromophores is computed by Forster resonant energy transfer (FRET) using the pairwise physical distances between chromophores from the PDB 5L8R (Protein Data Bank). We measure the global PSI network EET efficiency adopting well-known network theory indicators: the network efficiency (Eff) and the largest connected component (LCC). We also account the number of connected nodes/chromophores to P700 (CN), a new ad hoc measure we introduce here to indicate how many nodes in the network can actually transfer energy to the P700 reaction centre. We find that when progressively removing the weak links of lower EET, the Eff decreases, while the EET paths integrity (LCC and CN) is still preserved. This finding would show that the PSI is a resilient system owning a large window of functioning feasibility and it is completely impaired only when removing most of the network links. From the study of different types of chromophore, we propose different primary functions within the PSI system: chlorophyll a (CLA) molecules are the central nodes in the EET process, while other chromophore types have different primary functions. Furthermore, we perform nodes removal simulations to understand how the nodes/chromophores malfunctioning may affect PSI functioning. We discover that the removal of the CLA triggers the fastest decrease in the Eff, confirming that CAL is the main contributors to the high EET efficiency. Our outcomes open new perspectives of research, such comparing the PSI energy transfer efficiency of different natural and agricultural plant species and investigating the light-harvesting mechanisms of artificial photosynthesis both in plant agriculture and in the field of solar energy applications.

Histological changes in odontogenic parakeratinized keratocysts treated with marsupialization followed by enucleation

Background

The purpose of this study was to evaluate whether marsupialization treatment induces changes in the histology of odontogenic keratocyst epithelium and to compare our experience with the literature.

Material and Methods

A retrospective revision of histological samples was performed. 5 patients with odontogenic keratocyst treated with marsupialization follow by enucleation were selected. Histologic evaluation analyzed the changes in the keratocyst epithelium after marsupialization in terms of type of keratinization, thickness of the epithelium and connective tissue, the presence of acanthosis, the presence and grade of fibrosis, the type and grade of inflammation and the presence and number of mitotic figures and daughter cysts.

Results

In our case series, a variation of para-keratinized into ortho-keratinized keratocyst was found in one case, and no significant increases were observed in the epithelium and capsule thickness, or even in the level of inflammation. However, we observed an increase in fibrosis and qualitative changes in inflammation type.

Conclusions

Minor and major histological changes were associated with reduction in cyst volume, which resulted in a simpler and less invasive cystic enucleation after marsupialization.

Key words:Keratocyst, marsupialization, enucleation, histology, histological changes.

Conditioning of Superconductive Properties in Graph-Shaped Reticles

We report on phenomena observed in planar integrated networks obtained connecting superconducting island by Josephson tunnel junctions. These networks, identifiable as tree-like graphs, have branches consisting of series arrays of Josephson junctions which can be individually current biased and characterized. Both Josephson supercurrents and gap parameters of the arrays embedded in the graph structures display properties significantly different from those of “reference” arrays fabricated on the same chips and having identical geometrical shape. The temperature and magnetic field dependencies of the Josephson current of the embedded arrays both show a singular behavior when a critical value is reached by the Josephson characteristic energy. The gap parameter of the junctions generating the embedded arrays is higher than that of the junctions forming the reference geometrical arrays.

Salivary biomarkers for diagnosis of systemic diseases and malignant tumors. A systematic review

Background

Saliva evaluation could be a possible alternative to blood and/or tissue analyses, for researching specific molecules associated to the presence of systemic diseases and malignancies. The present systematic review has been designed in order to answer to the question “are there significant associations between specific salivary biomarkers and diagnosis of systemic diseases or malignancies?”.

Material and Methods

The Preferred Reporting Item for Systematic Reviews and Meta-analysis (PRISMA) statement was used to guide the review. The combinations of “saliva” and “systemic diseases” or “diagnosis” or “biomarkers” or “cancers” or “carcinoma” or “tumors”, were used to search Medline, Scopus and Web of Science databases. Endpoint of research has been set at May 2019. Studies were classified into 3 groups according to the type of disease investigated for diagnosis: 1) malignant tumors; 2) neurologic diseases and 3) inflammatory/metabolic/cardiovascular diseases. Assessment of quality has been assigned according to a series of questions proposed by the National Institute of Health. Level of evidence was assessed using the categories proposed in the Oxford Center for Evidence-Based medicine (CEMB) levels for diagnosis (2011).

Results

Seventy-nine studies met the inclusion and exclusion criteria. Fifty-one (64%) investigated malignant tumors, 14 (17.5%) neurologic and 14 (18.5%) inflammatory/cardiovascular/metabolic diseases. Among studies investigating malignant tumors, 12 (23.5%) were scored as “good” and 11 of these reported statistically significant associations between salivary molecules and pathology. Two and 5 studies were found to have a good quality, among those evaluating the association between salivary biomarkers and neurologic and inflammatory/metabolic/cardiovascular diseases, respectively.

Conclusions

The present systematic review confirms the existence of some “good” quality evidence to support the role of peculiar salivary biomarkers for diagnosis of systemic diseases (e.g. lung cancer and EGFR).

Key words:Salivary diagnostics, biomarkers, systemic diseases, malignant tumors, early diagnosis.

Natural position of the head: review of two-dimensional and three-dimensional methods of recording

Both the correct position of the patient's head and a standard system for the acquisition of images are essential for objective evaluation of the facial profile and the skull, and for longitudinal superimposition. The natural position of the head was introduced into orthodontics in the late 1950s, and is used as a postural basis for craniocervical and craniofacial morphological analysis. It can also have a role in the planning of the surgical correction of craniomaxillofacial deformities. The relatively recent transition in orthodontics from 2-dimensional to 3-dimensional imaging, and from analogue to digital technology, has renewed attention in finding a versatile method for the establishment of an accurate and reliable head position during the acquisition of serial records. In this review we discuss definition, clinical applications, and procedures to establish the natural head position and their reproducibility. We also consider methods to reproduce and record the position in two and three planes.

Determination of vertical dimension in prosthodontic rehabilitation of a growing patient with severe oligodontia

This report describes the oral rehabilitation of a young boy with severe oligodontia of primary dentition and complete anodontia of permanent dentition, treated by complete maxillary and partial mandibular removable dentures. Since the determination of a proper occlusal vertical dimension in paediatric patients is often difficult, treatment was achieved by means of a multidisciplinary approach involving conventional prosthodontic principles combined with cephalometric analysis and growth prediction. After a follow-up of two years a second lateral cephalogram was taken to evaluate the developmental changes in craniofacial morphology and the superimpositions method was performed, showing an improvement of both sagittal and vertical relationship between basal bones. In this case, the early prosthetic treatment resulted in enhanced aesthetics and masticatory function as well as skeletal growth changes.

Temporomandibular joint dysfunction in Moebius syndrome

AIM

Moebius syndrome is a rare condition characterised by bilateral facial and abducens nerve paralysis. In the present study, it was investigated the effect of the long term facial muscles hypoactivity on temporomandibular joint movements development.

METHODS

Accordingly with Terzis classification (Terzis, 2003), a wide sample of A type and B type Moebius patients was investigated for mandibular range of movements. Moebius patients were compared with a sample of healthy subjects.

RESULTS

Both type A and type B Moebius patients develop a severe articular movement reduction, especially during mouth opening. A highly significant difference was found between Moebius patients and the healthy group. No difference was found between A and B Moebius sub-samples.

CONCLUSION

The authors stress the importance of an early adequate rehabilitation of Moebius patients, in order to avoid the limitation of TMJ movement range.

Universal features of information spreading efficiency on d-dimensional lattices

A model for information spreading in a population of N mobile agents is extended to d-dimensional regular lattices. This model, already studied on two-dimensional lattices, also takes into account the degeneration of information as it passes from one agent to the other. Here, we find that the structure of the underlying lattice strongly affects the time tau at which the whole population has been reached by information. By comparing numerical simulations with mean-field calculations, we show that dimension d=2 is marginal for this problem and mean-field calculations become exact for d>2. Nevertheless, the striking nonmonotonic behavior exhibited by the final degree of information with respect to N and the lattice size L appears to be geometry independent.

Phase-ordering kinetics on graphs

We study numerically the phase-ordering kinetics following a temperature quench of the Ising model with single spin-flip dynamics on a class of graphs, including geometrical fractals and random fractals, such as the percolation cluster. For each structure we discuss the scaling properties and compute the dynamical exponents. We show that the exponent a_{chi} for the integrated response function, at variance with all the other exponents, is independent of temperature and of the presence of pinning. This universal character suggests a strict relation between a_{chi} and the topological properties of the networks, in analogy to what is observed on regular lattices.

Aging dynamics and the topology of inhomogenous networks

We study phase ordering on networks and we establish a relation between the exponent a(x) of the aging part of the integrated auto-response function and the topology of the underlying structures. We show that a(x) > 0 in full generality on networks which are above the lower critical dimension d(L), i.e., where the corresponding statistical model has a phase transition at finite temperature. For discrete symmetry models on finite ramified structures with T(c) = 0, which are at the lower critical dimension d(L), we show that a(x) is expected to vanish. We provide numerical results for the physically interesting case of the 2 - d percolation cluster at or above the percolation threshold, i.e., at or above d(L), and for other networks, showing that the value of a(x) changes according to our hypothesis. For O(N) models we find that the same picture holds in the large-N limit and that a(x) only depends on the spectral dimension of the network.

Topological filters and high-pass/low-pass devices for solitons in inhomogeneous networks

We show that, by inserting suitable finite networks at a site of a chain, it is possible to realize filters and high-pass/low-pass devices for solitons propagating along the chain. The results are presented in the framework of coupled optical waveguides; possible applications to different contexts, such as photonic lattices and Bose-Einstein condensates in optical networks are also discussed. Our results provide a first step in the control of the soliton dynamics through the network topology.

Efficiency of information spreading in a population of diffusing agents

We introduce a model for information spreading among a population of N agents diffusing on a square L x L lattice, starting from an informed agent (Source). Information passing from informed to unaware agents occurs whenever the relative distance is < or = 1. Numerical simulations show that the time required for the information to reach all agents scales as N(-alpha)L(beta), where alpha and beta are noninteger. A decay factor z takes into account the degeneration of information as it passes from one agent to another; the final average degree of information of the population tau(av)(z) is thus history dependent. We find that the behavior of tau(av)(z) is nonmonotonic with respect to N and L and displays a set of minima. Part of the results are recovered with analytical approximations.

Propagation of discrete solitons in inhomogeneous networks

In many physical applications solitons propagate on supports whose topological properties may induce new and interesting effects. In this paper, we investigate the propagation of solitons on chains with a topological inhomogeneity generated by inserting a finite discrete network on a chain. For networks connected by a link to a single site of the chain, we derive a general criterion yielding the momenta for perfect reflection and transmission of traveling solitons and we discuss solitonic motion on chains with topological inhomogeneities.

Localized states on comb lattices

Complex networks and graphs provide a general description of a great variety of inhomogeneous discrete systems. These range from polymers and biomolecules to complex quantum devices, such as arrays of Josephson junctions, microbridges, and quantum wires. We introduce a technique, based on the analysis of the motion of a random walker, that allows us to determine the density of states of a general local Hamiltonian on a graph, when the potential differs from zero on a finite number of sites. We study in detail the case of the comb lattice and we derive an analytic expression for the elements of the resolvent operator of the Hamiltonian, giving its complete spectrum.

Diffusive thermal dynamics for the Ising ferromagnet

We introduce a thermal dynamics for the Ising ferromagnet where the energy variations occurring within the system exhibit a diffusive character typical of thermalizing agents such as, e.g., localized excitations. Time evolution is provided by a walker hopping across the sites of the underlying lattice according to local probabilities depending on the usual Boltzmann weight at a given temperature. Despite the canonical hopping probabilities the walker drives the system to a stationary state which is not reducible to the canonical equilibrium state in a trivial way. The system still exhibits a magnetic phase transition occurring at a finite value of the temperature larger than the canonical one. The dependence of the model on the density of walkers realizing the dynamics is also discussed. Interestingly the differences between the stationary state and the Boltzmann equilibrium state decrease with increasing number of walkers.

n--> infinity limit of O(n) ferromagnetic models on graphs

Thirty years ago, H. E. Stanley showed that an O(n) spin model on a lattice tends to a spherical model as n-->infinity. This means that at any temperature the corresponding free energies coincide. This fundamental result is no longer valid on more general discrete structures lacking in translation invariance, i.e., on graphs. However, only the singular parts of the free energies determine the critical behavior of the two statistical models. Here we show that for ferromagnetic models such singular parts still coincide even on graphs in the thermodynamic limit. This implies that the critical exponents of O(n) models on graphs for n-->infinity tend to the spherical ones and depend only on the graph spectral dimension.

Inverse Mermin-Wagner theorem for classical spin models on graphs

In this paper we present the inversion of the Mermin-Wagner theorem on graphs, by proving the existence of spontaneous magnetization at finite temperature for classical spin models on transient on the average graphs, i.e., graphs where a random walker returns to its starting point with an average probability F<1. This result, which is here proven for models with O(n) symmetry, includes as a particular case n=1, providing a very general condition for spontaneous symmetry breaking on inhomogeneous structures even for the Ising model.

Increased plasma level of vascular endothelial glycoprotein thrombomodulin as an early indicator of endothelial damage in bone marrow transplantation

We investigated the nature of hemostatic alterations occurring after bone marrow transplantation. In 45 patients, we evaluated the coagulation parameters, naturally occurring anticoagulants and thrombomodulin at days +15 and +22 after conditioning therapy. It was observed that endothelial cell damage is a central pathogenetic mechanism in some BMT complications. The increased plasma level of thrombomodulin after conditioning therapy is therefore discussed as a marker of endothelial cell injury. At day +15 a significant increase of fibrinogen from 276.1 mg/dI to 389.1 mg/dI was observed, while the natural anticoagulants all decreased significantly. Eleven patients with clinical complications related to endothelial damage had a significant thrombomodulin increase which, in uncomplicated patients, remained unchanged or resulted in lower than baseline values. Analysis of the data shows a strong correlation between clinical findings, reflecting endothelial cell injury and thrombomodulin increase when the increment is > or = 30%. We found a significant elevation in thrombomodulin in 70% of clinical complications related to endothelial cell damage namely: septicemia, GVHD, VOD. There were four cases (or 9%) of false positive data, and only two (or 4.5%) of false negative results. We therefore propose thrombomodulin assessment as a valid parameter to monitor chemotherapy toxicity-related complications.