Oral hygiene indirect instruction and periodic reinforcements: effects on index plaque in schoolchildren

The aim of this study was to evaluate the effectiveness of the indirect instruction and the influence of the periodic reinforcement on the plaque index in schoolchildren. Forty schoolchildren aged from 7 to 9 years old were selected from a public school. After determining the initial O'Leary Plaque Index all schoolchildren were submitted to a program for oral hygiene through indirect instruction -"The Smiling Robot". The schoolchildren were divided into 2 groups: with and without motivation reinforcement. The index plaque exam was performed in both groups after 30, 60 and 90 days of the educational program. Comparing the groups, the plaque index decreasing could be observed in the group with reinforcement with statistically significant difference. For the group with reinforcement, statistically significant difference among the evaluations was found. For the group without reinforcement, significant decrease in the plaque index was found after 30 days when compared to the first, third and fourth evaluations. The indirect instruction with "The Smiling Robot "promoted a positive initial impact on the decrease of plaque index in the schoolchildren. The periodic reinforcements showed more suitable results and significant reduction of the plaque index in the course of the evaluations.

2D supramolecular polymers: nanosized, water-soluble "sheets"

Self – assembly is a powerful tool for the construction of highly organized nanostructures [1]. Therefore, the possibility to control and predict pathways of molecular ordering on the nanoscale level is a critical issue for the production of materials with tunable and adaptive macroscopic properties. Herein, we demonstrate that designed molecule Py3 forms dimensionally - defined supramolecular assemblies under thermodynamic conditions in water [2]. To study Py3 self-assembly, we carried out whole set of spectroscopic and microscopic experiments. The factors influencing stability, morphology and behavior of «nanosheets» in multicomponent systems are discussed

Recent advances into understanding some aspects of the structure and function of mammalian and avian lungs

Recent findings are reported about certain aspects of the structure and function of the mammalian and avian lungs that include (a) the architecture of the air capillaries (ACs) and the blood capillaries (BCs); (b) the pulmonary blood capillary circulatory dynamics; (c) the adaptive molecular, cellular, biochemical, compositional, and developmental characteristics of the surfactant system; (d) the mechanisms of the translocation of fine and ultrafine particles across the airway epithelial barrier; and (e) the particle-cell interactions in the pulmonary airways. In the lung of the Muscovy duck Cairina moschata, at least, the ACs are rotund structures that are interconnected by narrow cylindrical sections, while the BCs comprise segments that are almost as long as they are wide. In contrast to the mammalian pulmonary BCs, which are highly compliant, those of birds practically behave like rigid tubes. Diving pressure has been a very powerful directional selection force that has influenced phenotypic changes in surfactant composition and function in lungs of marine mammals. After nanosized particulates are deposited on the respiratory tract of healthy human subjects, some reach organs such as the brain with potentially serious health implications. Finally, in the mammalian lung, dendritic cells of the pulmonary airways are powerful agents in engulfing deposited particles, and in birds, macrophages and erythrocytes are ardent phagocytizing cellular agents. The morphology of the lung that allows it to perform different functions-including gas exchange, ventilation of the lung by being compliant, defense, and secretion of important pharmacological factors-is reflected in its "compromise design."

Biomechanical effects of environmental and engineered particles on human airway smooth muscle cells

The past decade has seen significant increases in combustion-generated ambient particles, which contain a nanosized fraction (less than 100 nm), and even greater increases have occurred in engineered nanoparticles (NPs) propelled by the booming nanotechnology industry. Although inhalation of these particulates has become a public health concern, human health effects and mechanisms of action for NPs are not well understood. Focusing on the human airway smooth muscle cell, here we show that the cellular mechanical function is altered by particulate exposure in a manner that is dependent upon particle material, size and dose. We used Alamar Blue assay to measure cell viability and optical magnetic twisting cytometry to measure cell stiffness and agonist-induced contractility. The eight particle species fell into four categories, based on their respective effect on cell viability and on mechanical function. Cell viability was impaired and cell contractility was decreased by (i) zinc oxide (40-100 nm and less than 44 microm) and copper(II) oxide (less than 50 nm); cell contractility was decreased by (ii) fluorescent polystyrene spheres (40 nm), increased by (iii) welding fumes and unchanged by (iv) diesel exhaust particles, titanium dioxide (25 nm) and copper(II) oxide (less than 5 microm), although in none of these cases was cell viability impaired. Treatment with hydrogen peroxide up to 500 microM did not alter viability or cell mechanics, suggesting that the particle effects are unlikely to be mediated by particle-generated reactive oxygen species. Our results highlight the susceptibility of cellular mechanical function to particulate exposures and suggest that direct exposure of the airway smooth muscle cells to particulates may initiate or aggravate respiratory diseases.

Decision-making in amnesia: do advantageous decisions require conscious knowledge of previous behavioural choices?

Previous work has reported that in the Iowa gambling task (IGT) advantageous decisions may be taken before the advantageous strategy is known [Bechara, A., Damasio, H., Tranel, D., ; Damasio, A. R. (1997). Deciding advantageously before knowing the advantageous strategy. Science, 275, 1293-1295]. In order to test whether explicit memory is essential for the acquisition of a behavioural preference for advantageous choices, we measured behavioural performance and skin conductance responses (SCRs) in five patients with dense amnesia following damage to the basal forebrain and orbitofrontal cortex, six amnesic patients with damage to the medial temporal lobe or the diencephalon, and eight control subjects performing the IGT. Across 100 trials healthy participants acquired a preference for advantageous choices and generated large SCRs to high levels of punishment. In addition, their anticipatory SCRs to disadvantageous choices were larger than to advantageous choices. However, this dissociation occurred much later than the behavioural preference for advantageous alternatives. In contrast, though exhibiting discriminatory autonomic SCRs to different levels of punishment, 9 of 11 amnesic patients performed at chance and did not show differential anticipatory SCRs to advantageous and disadvantageous choices. Further, the magnitude of anticipatory SCRs did not correlate with behavioural performance. These results suggest that the acquisition of a behavioural preference--be it for advantageous or disadvantageous choices--depends on the memory of previous reinforcements encountered in the task, a capacity requiring intact explicit memory.

Direct combination of nanoparticle fabrication and exposure to lung cell cultures in a closed setup as a method to simulate accidental nanoparticle exposure of humans

The tremendous application potential of nanosized materials stays in sharp contrast to a growing number of critical reports of their potential toxicity. Applications of in vitro methods to assess nanoparticles are severely limited through difficulties in exposing cells of the respiratory tract directly to airborne engineered nanoparticles. We present a completely new approach to expose lung cells to particles generated in situ by flame spray synthesis. Cerium oxide nanoparticles from a single run were produced and simultaneously exposed to the surface of cultured lung cells inside a glovebox. Separately collected samples were used to measure hydrodynamic particle size distribution, shape, and agglomerate morphology. Cell viability was not impaired by the conditions of the glovebox exposure. The tightness of the lung cell monolayer, the mean total lamellar body volume, and the generation of oxidative DNA damage revealed a dose-dependent cellular response to the airborne engineered nanoparticles. The direct combination of production and exposure allows studying particle toxicity in a simple and reproducible way under environmental conditions.

Bioavailability of silver nanoparticles and ions: from a chemical and biochemical perspective

Owing to their antimicrobial properties, silver nanoparticles (NPs) are the most commonly used engineered nanomaterial for use in a wide array of consumer and medical applications. Many discussions are currently ongoing as to whether or not exposure of silver NPs to the ecosystem (i.e. plants and animals) may be conceived as harmful or not. Metallic silver, if released into the environment, can undergo chemical and biochemical conversion which strongly influence its availability towards any biological system. During this process, in the presence of moisture, silver can be oxidized resulting in the release of silver ions. To date, it is still debatable as to whether any biological impact of nanosized silver is relative to either its size, or to its ionic constitution. The aim of this review therefore is to provide a comprehensive, interdisciplinary overview--for biologists, chemists, toxicologists as well as physicists--regarding the production of silver NPs, its (as well as in their ionic form) chemical and biochemical behaviours towards/within a multitude of relative and realistic biological environments and also how such interactions may be correlated across a plethora of different biological organisms.

Size-dependent accumulation of particles in lysosomes modulates dendritic cell function through impaired antigen degradation.

INTRODUCTION Nanosized particles may enable therapeutic modulation of immune responses by targeting dendritic cell (DC) networks in accessible organs such as the lung. To date, however, the effects of nanoparticles on DC function and downstream immune responses remain poorly understood. METHODS Bone marrow-derived DCs (BMDCs) were exposed in vitro to 20 or 1,000 nm polystyrene (PS) particles. Particle uptake kinetics, cell surface marker expression, soluble protein antigen uptake and degradation, as well as in vitro CD4(+) T-cell proliferation and cytokine production were analyzed by flow cytometry. In addition, co-localization of particles within the lysosomal compartment, lysosomal permeability, and endoplasmic reticulum stress were analyzed. RESULTS The frequency of PS particle-positive CD11c(+)/CD11b(+) BMDCs reached an early plateau after 20 minutes and was significantly higher for 20 nm than for 1,000 nm PS particles at all time-points analyzed. PS particles did not alter cell viability or modify expression of the surface markers CD11b, CD11c, MHC class II, CD40, and CD86. Although particle exposure did not modulate antigen uptake, 20 nm PS particles decreased the capacity of BMDCs to degrade soluble antigen, without affecting their ability to induce antigen-specific CD4(+) T-cell proliferation. Co-localization studies between PS particles and lysosomes using laser scanning confocal microscopy detected a significantly higher frequency of co-localized 20 nm particles as compared with their 1,000 nm counterparts. Neither size of PS particle caused lysosomal leakage, expression of endoplasmic reticulum stress gene markers, or changes in cytokines profiles. CONCLUSION These data indicate that although supposedly inert PS nanoparticles did not induce DC activation or alteration in CD4(+) T-cell stimulating capacity, 20 nm (but not 1,000 nm) PS particles may reduce antigen degradation through interference in the lysosomal compartment. These findings emphasize the importance of performing in-depth analysis of DC function when developing novel approaches for immune modulation with nanoparticles.