Front interaction induces excitable behavior.

Spatially extended systems can support local transient excitations in which just a part of the system is excited. The mechanisms reported so far are local excitability and excitation of a localized structure. Here we introduce an alternative mechanism based on the coexistence of two homogeneous stable states and spatial coupling. We show the existence of a threshold for perturbations of the homogeneous state. Subthreshold perturbations decay exponentially. Superthreshold perturbations induce the emergence of a long-lived structure formed by two back to back fronts that join the two homogeneous states. While in typical excitability the trajectory follows the remnants of a limit cycle, here reinjection is provided by front interaction, such that fronts slowly approach each other until eventually annihilating. This front-mediated mechanism shows that extended systems with no oscillatory regimes can display excitability.

Competition between drift and spatial defects leads to oscillatory and excitable dynamics of dissipative solitons.

We have reported in Phys. Rev. Lett. 110, 064103 (2013)PRLTAO0031-900710.1103/PhysRevLett.110.064103 that in systems which otherwise do not show oscillatory dynamics, the interplay between pinning to a defect and pulling by drift allows the system to exhibit excitability and oscillations. Here we build on this work and present a detailed bifurcation analysis of the various dynamical instabilities that result from the competition between a pulling force generated by the drift and a pinning of the solitons to spatial defects. We show that oscillatory and excitable dynamics of dissipative solitons find their origin in multiple codimension-2 bifurcation points. Moreover, we demonstrate that the mechanisms leading to these dynamical regimes are generic for any system admitting dissipative solitons.

Effects of inhomogeneities and drift on the dynamics of temporal solitons in fiber cavities and microresonators.

In [Phys. Rev. Lett. 110, 064103 (2013)], using the Swift-Hohenberg equation, we introduced a mechanism that allows to generate oscillatory and excitable soliton dynamics. This mechanism was based on a competition between a pinning force at inhomogeneities and a pulling force due to drift. Here, we study the effect of such inhomogeneities and drift on temporal solitons and Kerr frequency combs in fiber cavities and microresonators, described by the Lugiato-Lefever equation with periodic boundary conditions. We demonstrate that for low values of the frequency detuning the competition between inhomogeneities and drift leads to similar dynamics at the defect location, confirming the generality of the mechanism. The intrinsic periodic nature of ring cavities and microresonators introduces, however, some interesting differences in the final global states. For higher values of the detuning we observe that the dynamics is no longer described by the same mechanism and it is considerably more complex.

Do school based anti-smoking campaigns delivered by oral health therapists work?

BACKGROUND: The dental profession has a pivotal role in cancer prevention. In Queensland, oral health therapists (OHTs) are in a unique position to provide quality smoking cessation programmes and intervention strategies to young adolescents through the school based oral health services they provide. METHODS: This study undertook a smoking cessation and prevention programme targeted to female high school students in a dental setting. An oral health therapist delivered an anti-smoking message and educated adolescents of the health-risk effects of smoking. RESULTS: A total of 1217 female students were recruited with 621 (51%) in the intervention group and 596 (49%) in the control group. There was a significant improvement in the knowledge of both systemic and oral health effects of smoking in the intervention group (p < 0.04). The results of the study demonstrated that the dental setting is an effective avenue for educating young individuals on smoking related conditions. CONCLUSIONS: A smoking cessation and prevention programme targeted to female high school students in a dental setting provides a novel means of delivering an anti-smoking message and educating adolescents of the health-risk effects of smoking.

A case of primary diffuse large B-cell non-Hodgkin's lymphoma misdiagnosed as chronic periapical periodontitis.

Lymphoma is a malignant neoplasm of component cells of the lymphoid system which is very rare in the jaws. Here we report a case of primary diffuse large B-cell lymphoma located in the periapical region of a mandibular molar which was misdiagnosed as chronic periapical periodontitis. The present case was diagnosed at an early stage and effectively managed by chemotherapy. Although lymphoma of the mandible is rare, it must be considered in the differential diagnosis of radiolucent lesions in this region. Lack of knowledge of this rare presentation may lead to delays in diagnosis and poor prognosis.

Dissipative soliton excitability induced by spatial inhomogeneities and drift.

We show that excitability is generic in systems displaying dissipative solitons when spatial inhomogeneities and drift are present. Thus, dissipative solitons in systems which do not have oscillatory states, such as the prototypical Swift-Hohenberg equation, display oscillations and type I and II excitability when adding inhomogeneities and drift to the system. This rich dynamical behavior arises from the interplay between the pinning to the inhomogeneity and the pulling of the drift. The scenario presented here provides a general theoretical understanding of oscillatory regimes of dissipative solitons reported in semiconductor microresonators. Our results open also the possibility to observe this phenomenon in a wide variety of physical systems.

Long-term use of antimalarial drugs in rheumatic diseases.

OBJECTIVES: To evaluate long-term use of antimalarial drugs and to analyse all causes of discontinuation. METHODS: This is a retrospective study of a cohort of rheumatic diseases patients on antimalarials, during a maximum period of 17.5 years. Case was defined as antimalarial treatment discontinuation due to: a) lack of efficacy, b) adverse events, and c) other causes. Survival techniques were used to estimate the incidence rate (IR) per 1,000 patient-years with the 95% Confidence Interval (95% CI) of antimalarial treatment discontinuation. Cox regression models were conducted to evaluate possible associated factors to antimalarial discontinuation. RESULTS: One thousand, two hundred and ninety-one medical records were reviewed, and 778 patients were included. Patients started 869 different courses of treatment, with a total follow-up of 2,263 person-years. The IR of global discontinuation was 204 (95% CI 186-224). Fifty-two per cent of the treatments stopped were related to adverse events, 14% to lack of efficacy; and 34% to other reasons (refusal to take medication, ocular comorbidity, remission, or pregnancy). Adverse events discontinuations were related to non-ophthalmologic reasons in 54.5% (gastrointestinal, neuro-psychiatric, skin problems), and to ophthalmologic adverse events in 45.5%. Nine patients suffered definite presence of antimalarial retinopathy (IR: 3.97 [IC 95%: 2.06-7.62]) and one of them irreversible loss of vision (IR: 0.44 [IC 95%: 0.06-3.12]). Women, increasing age, and chloroquine vs. hydroxychloroquine use, increased the risk of discontinuation due to ophthalmologic adverse events. CONCLUSIONS: Results suggest that antimalarials have a good balance between benefit and risk. However, we noted a number of discontinuations due to both inefficacy and adverse events. The potential for an unusual but serious ophthalmologic toxicity emphasises the importance of close ophthalmologic monitoring.

Early activation of the interleukin-23-17 axis in a murine model of oropharyngeal candidiasis.

Candida albicans is an oral commensal yeast that causes oropharyngeal candidiasis (OPC) in immunocompromised individuals. The immunological pathways involved in OPC have been revisited after the interleukin-17 (IL-17) pathway was implicated in fungal immunity. We studied immediate (<24 h) and adaptive (3-6 day) IL-12 and IL-23-17 pathway activation in naive p40(-/-) mice, which lack IL-12 and IL-23 and develop severe, chronic OPC upon oral inoculation with C. albicans. Macrophages from p40(-/-) mice were less efficient than C57BL/6J controls at killing C. albicans in vitro but very low numbers in the oral mucosae of infected C57BL/6J mice suggest that they are not critical in vivo, at least in this strain. Migration of macrophages to regional lymph nodes of infected p40(-/-) mice was impaired; however, dendritic cell migration was not affected. Recombinant IL-12 therapy provided only temporary relief from OPC, suggesting that IL-23 is required for full protection. In C57BL/6J mice, but not p40(-/-) mice, messenger RNAs encoding IL-23p19 and IL-17 were induced in the oral mucosa within 24 h of infection (6 ± 0.6 and 12 ± 2.7-fold). By day 6 of infection in C57BL/6J mice, IL-17A messenger RNA level had increased 5.1 ± 1.8 and 83 ± 21-fold in regional lymph nodes and oral tissues respectively. Ablation of p40 was associated with delayed or abrogated induction of IL-17A pathway targets (monocyte chemoattractant protein-1, IL-6 and macrophage inflammatory protein-2), and a lack of organized recruitment of neutrophils to the infected oral mucosa. Overall our data show that the IL-23-17A axis is activated early in the oral mucosae of immunologically naive mice with OPC.

Nonlocality-induced front-interaction enhancement.

We demonstrate that nonlocal coupling strongly influences the dynamics of fronts connecting two equivalent states. In two prototype models we observe a large amplification in the interaction strength between two opposite fronts increasing front velocities several orders of magnitude. By analyzing the spatial dynamics we prove that way beyond quantitative effects, nonlocal terms can also change the overall qualitative picture by inducing oscillations in the front profile. This leads to a mechanism for the formation of localized structures not present for local interactions. Finally, nonlocal coupling can induce a steep broadening of localized structures, eventually annihilating them.

Immunohistochemical localisation of extracellular matrix proteins in the periodontium during cementogenesis in the rat molar.

OBJECTIVE: The development of the periodontium involves the coordinated expression of numerous extracellular matrix (ECM) macromolecules and their receptors (integrins). The aim of this study was to determine the expression of selected hard and soft tissue matrix molecules and the integrin alpha5beta1 in the periodontal tissues, during cementogenesis in the rat molar. METHODS: Using immunohistochemical methods, the distribution of the extracellular matrix proteins, fibronectin, tenascin, and bone sialoprotein (BSP), as well as the integrin subunits alpha5 and beta1 were studied in rats aged 3, 5 and 8 weeks. RESULTS: Fibronectin was widely distributed in the gingival epithelium, gingival connective tissue and in the periodontal ligament. Tenascin expression was less marked compared with fibronectin, but was more distinctly associated with cells and peri-cellular areas of the epithelial-connective tissue interface, the gingiva and within the periodontal ligament. The fibronectin-receptor alpha5beta1 integrins were expressed by epithelial cells, periodontal ligament cells and gingival fibroblasts. A notable finding was the increased staining intensity of fibronectin, tenascin and alpha5beta1 integrin in all 5-week old molar sections in the periodontal ligament matrix and cells, apical to the cemento-enamel junction (CEJ) along the alveolar crest (AC) ridge height. Bone sialoprotein was distinctly associated with the hard tissues of the periodontium as acellular cementum and alveolar bone matrix expressed bone sialoprotein throughout all sections, in all age groups. CONCLUSIONS: In conclusion, this study has demonstrated the selective distribution of several hard and soft tissue matrix molecules during periodontogenesis. The results highlight the complex nature of interactions of various proteins and molecules during development. The interactions between these molecules and their specific roles in development and regeneration await further investigation.

Immunohistochemical localization of fibromodulin in the periodontium during cementogenesis and root formation in the rat molar.

BACKGROUND: Cementum is essential for periodontal regeneration, as it provides anchorage between the root surface and the periodontal ligament. A variety of macromolecules present in the extracellular matrix of the periodontium, including proteoglycans, are likely to play a regulatory role in cementogenesis. Recently, the small leucine-rich proteoglycan, fibromodulin, has been isolated from bovine periodontal ligament and localized in bovine cementum, as well as in human periodontal ligament. OBJECTIVE: The aim of this study was to examine the distribution of fibromodulin during cementogenesis and root formation. METHODS: A standard indirect immunoperoxidase technique was employed, using an antifibromodulin polyclonal antibody on sections of molar teeth from rats aged 3, 5 and 8 weeks. RESULTS: Immunoreactivity to fibromodulin was evident in the periodontal ligament in all sections. An intense positive stain was observed in the extracellular matrix where the periodontal ligament fibers insert into the alveolar bone and where the Sharpey's fibers insert into the cementum. There was no staining evident in the mineralized cellular and acellular cementum. The intensity of immunoreactivity to the antifibromodulin antibody increased proportionally with increasing tissue maturation. CONCLUSION: The results from this study suggest that fibromodulin is a significant component of the extracellular matrix in the periodontal ligament during development, and may play a regulatory role in the mineralization process or maintaining homeostasis at the hard-soft tissue interface during cementogenesis.

[Development of pre-hepatic portal hypertension of the rat]. / Tipos evolutivos de hipertensión portal prehepática en la rata.

OBJECTIVE: A long-term study of the prehepatic portal hypertension model by triple stenosing ligation of the portal vein in the rat. METHOD: A cluster analysis of the animals in the different evolutive stages of portal hypertension (1 1/2, 6, 12 and 14 months) has been carried out. This analysis has made it possible to identify three homogeneous groups (A, B and C) in relationship to the liver weight. RESULTS: The animals with liver atrophy (group C) show a decrease of body, splenic and testicular weights as well as a higher development of the portosystemic collateral circulation in relation to the A and B groups. CONCLUSION: The percentage of animals belonging to the group C decrease progressively during the evolution of portal hypertension and those animals corresponding to the group A, in which is superior the liver weight, increase, while the B group does not change.