Ultrastructure des microcalcifications du mésenchyme pulpaire des dents temporaires humaines

Scanning electron microscopic observations of pulp calcifications in deciduous molars were correlated with microradiographic findings.Numerous spherical calcifications were found in appearance similar to those in the permanent dentition.In a second type, mineralization took the form of diffuse deposits of calcium.The discrete diffuse foci coalesced into large islands of mineralized connective tissue.A third type of calcification was observed in which rhombic crystals were associated in a spherulitic pattern.The exact cause of the crystal formation is unknown. Moreover, as we are aware, the spherulitic calcifications have never been previously reported in this location.The preliminary results indicated that mineralization in the pulp of deciduous molars, takes a variety of forms, suggesting that calcium deposition can occur by different processes.L’objectif de ce travail est de corréler les observations au microscope électronique à balayage et en microradiographie, des micro-calcifications du mésenchyme pulpaire des molaires temporaires.Les résultats montrent que la pulpe contient de nombreuses calcifications sphériques ou ovalaires correspondant à la définition des pulpolithes.Un deuxième type de minéralisation a été trouvé sous la forme de dépôts diffus de sels de calcium. La coalescence des calcifications diffuses aboutit à la formation de plages plus larges de tissu minéralisé.Un troisième type de calcification est constitué de cristaux rhombes organisés sous la forme de sphérulites.Ce type de concrétions dont l’origine est inconnue ne paraît pas avoir été observée précédemment au microscope électronique à balayage.Ces résultats préliminaires montrent que les calcifications apparaîssent sous des formes variées suggérant que des mécanismes très différents gouvernent la promotion des dépôts de sels de calcium dans le mésenchyme pulpaire des molaires temporaires

Does turbulence affect the habitat choice of Atlantic salmon parr?

Habitat preferences of Atlantic salmon parr are commonly described using mean flow velocity, water depth, and substrate as habitat variables, and a variety of habitat models have been developed using these variables to predict habitat quality. However, Atlantic salmon parr live in highly turbulent streams and rivers, in which intense fluctuations of flow velocity occur. Habitat preferences that consider the high variability of flow velocity have not been studied, and this although it has been shown in laboratory experiments that turbulence may affect the behavior and energetics of fish. Consequently, we studied the use of turbulent flow by Atlantic salmon parr in Patapédia River, Québec, Canada using radio-telemetry. We analyzed summer habitat preferences of individual parr in relation to several dynamic hydraulic variables such as standard deviation of flow velocity, turbulent kinetic energy, Froude number, and shear stress, and compared them with the habitat availability within the river reach. Our results revealed that in a natural flow environment, parr display a high individual variability in habitat preferences in relation to flow turbulence. Such heterogeneous habitat preferences suggest that individuals are not constrained to single habitat types and exhibit flexible habitat use. Furthermore, no differences were observed in habitat preferences between the four daily periods (dawn, day, dusk, and night) within individual parr

Characterisation of Bioglass based foams developed via replication of natural marine sponges

A comparative characterisation of Bioglass based scaffolds for bone tissue engineering applications developed via a replication technique of natural marine sponges as sacrificial template is presented, focusing on their architecture and mechanical properties. The use of these sponges presents several advantages, including the possibility of attaining higher mechanical properties than those scaffolds made by foam replica method (up to 4 MPa) due to a decrease in porosity (68-76%) without affecting the pore interconnectivity (higher than 99%). The obtained pore structure possesses not only pores with a diameter in the range 150-500 mm, necessary to induce bone ingrowth, but also pores in the range of 0-200 mm, which are requested for complete integration of the scaffold and for neovascularisation. In this way, it is possible to combine the main properties that a three-dimensional scaffold should have for bone regeneration: interconnected and high porosity, adequate mechanical properties and bioactivity

Systematic review: probiotics in the management of lower gastrointestinal symptoms in clinical practice – an evidence-based international guide

Background Evidence suggests that the gut microbiota play an important role in gastrointestinal problems. Aim To give clinicians a practical reference guide on the role of specified probiotics in managing particular lower gastrointestinal symptoms/problems by means of a systematic review-based consensus. Methods Systematic literature searching identified randomised, placebo-controlled trials in adults; evidence for each symptom/problem was graded and statements developed (consensus process; 10-member panel). As results cannot be generalised between different probiotics, individual probiotics were identified for each statement. Results Thirty seven studies were included; mostly on irritable bowel syndrome [IBS; 19 studies; treatment responder rates: 18–80% (specific probiotics), 5–50% (placebo)] or antibiotic-associated diarrhoea (AAD; 10 studies). Statements with 100% agreement and ‘high’ evidence levels indicated that: (i) specific probiotics help reduce overall symptom burden and abdominal pain in some IBS patients; (ii) in patients receiving antibiotics/Helicobacter pylori eradication therapy, specified probiotics are helpful as adjuvants to prevent/reduce the duration/intensity of AAD; (iii) probiotics have favourable safety in patients in primary care. Items with 70–100% agreement and ‘moderate’ evidence were: (i) specific probiotics help relieve overall symptom burden in some patients with diarrhoea-predominant IBS, and reduce bloating/distension and improve bowel movement frequency/consistency in some IBS patients and (ii) with some probiotics, improved symptoms have led to improvement in quality of life. Conclusions Specified probiotics can provide benefit in IBS and antibiotic-associated diarrhoea; relatively few studies in other indications suggested benefits warranting further research. This study provides practical guidance on which probiotic to select for a specific problem

Habitat-Mediated Facilitation and Counteracting Ecosystem Engineering Interactively Influence Ecosystem Responses to Disturbance

Recovery of an ecosystem following disturbance can be severely hampered or even shift altogether when a point disturbance exceeds a certain spatial threshold. Such scale-dependent dynamics may be caused by preemptive competition, but may also result from diminished self-facilitation due to weakened ecosystem engineering. Moreover, disturbance can facilitate colonization by engineering species that alter abiotic conditions in ways that exacerbate stress on the original species. Consequently, establishment of such counteracting engineers might reduce the spatial threshold for the disturbance, by effectively slowing recovery and increasing the risk for ecosystem shifts to alternative states. We tested these predictions in an intertidal mudflat characterized by a two-state mosaic of hummocks (humps exposed during low tide) dominated by the sediment-stabilizing seagrass Zostera noltii) and hollows (low-tide waterlogged depressions dominated by the bioturbating lugworm Arenicola marina). In contrast to expectations, seagrass recolonized both natural and experimental clearings via lateral expansion and seemed unaffected by both clearing size and lugworm addition. Near the end of the growth season, however, an additional disturbance (most likely waterfowl grazing and/or strong hydrodynamics) selectively impacted recolonizing seagrass in the largest (1 m2) clearings (regardless of lugworm addition), and in those medium (0.25 m2) clearings where lugworms had been added nearly five months earlier. Further analyses showed that the risk for the disturbance increased with hollow size, with a threshold of 0.24 m2. Hollows of that size were caused by seagrass removal alone in the largest clearings, and by a weaker seagrass removal effect exacerbated by lugworm bioturbation in the medium clearings. Consequently, a sufficiently large disturbance increased the vulnerability of recolonizing seagrass to additional disturbance by weakening seagrass engineering effects (sediment stabilization). Meanwhile, the counteracting ecosystem engineering (lugworm bioturbation) reduced that threshold size. Therefore, scale-dependent interactions between habitat-mediated facilitation, competition and disturbance seem to maintain the spatial two-state mosaic in this ecosystem

Endotracheal tubes and fluid aspiration: An in vitro evaluation of new cuff technologies

© 2017 The Author(s). Background: Aspiration of subglottic secretions past the endotracheal tube (ETT) cuff is a prerequisite for developing ventilator-associated pneumonia (VAP). Subglottic secretion drainage (SSD) ETTs reduce aspiration of subglottic secretions and have demonstrated lower VAP rates. We compared the performance of seven SSD ETTs against a non-SSD ETT in preventing aspiration below inflated cuffs. Methods: ETTs were positioned vertically in 2 cm diameter cylinders. Four ml of a standard microbial suspension was added above inflated cuffs. After 1 h, aspiration was measured and ETTs demonstrating no leakage were subjected to rotational movement and evaluation over 24 h. Collected aspirated fluid was used to inoculate agar media and incubated aerobically at 37 °C for 24 h. The aspiration rate, volume and number of microorganisms that leaked past the cuff was measured. Experiments were repeated (×10) for each type of ETT, with new ETTs used for each repeat. Best performing ETTs were then tested in five different cylinder diameters (1.6, 1.8, 2.0, 2.2 and 2.4 cm). Experiments were repeated as above using sterile water. Volume and time taken for aspiration past the cuff was measured. Experiments were repeated (×10) for each type of ETT. Results were analysed using non-parametric tests for repeated measures. Results: The PneuX ETT prevented aspiration past the cuff in all experiments. All other ETTs allowed aspiration, with considerable variability in performance. The PneuX ETT was statistically superior in reducing aspiration compared to the SealGuard (p < 0.009), KimVent (p < 0.002), TaperGuard (p < 0.004), Lanz (p < 0.001), ISIS (p < 0.001), SACETT (p < 0.001) and Soft Seal (p < 0.001) ETTs. Of the 4 ETTs tested in differing cylinder sizes, the PneuX significantly reduced aspiration across the range of diameters compared to the SealGuard (p < 0.0001), TaperGuard (p < 0.0001) and KimVent (p < 0.0001) ETTs. Conclusions: ETTs showed substantial variation in fluid aspiration, relating to cuff material and design. Variability in performance was likely due to the random manner in which involutional folds form in the inflated ETT cuff. The PneuX ETT was the only ETT able to consistently prevent aspiration past the cuff in all experiments