Dry Tissue Research Articles

Adaptation strategy of karst forests: Evidence from the community-weighted mean of plant functional traits.

Conservative survival strategy of plants growing in harsh karst habitats is observed from the view of plant functional traits, such as morphological traits and ecological stoichiometry. However, whether the plant communities in karst forests with high species turnover adopt a conservative strategy remains undetermined. This study comprehensively investigated the characteristics of functional traits of dominant plant species in four forests (i.e. Platycarya strobilacea, Quercus fabri, Quercus variabilis, and Pinus massoniana forests) in a trough‐valley karst watershed in Northern Guizhou Province, Southwestern China to explore the adaptation strategy of karst forests at the community level. At the organ and the species levels, traits differed among species, and the leaf and the bark morphological traits and root C:N:P ecological stoichiometry presented large interspecific variations. At the community level, the P. massoniana forest presented the lowest specific root length and dry matter content and tissue density of roots, branch, twig, and bark; the Q. fabri and the Q. variabilis forests displayed low specific leaf area and high dry matter content and tissue density of roots, branch, and twig; and the Platycarya strobilacea forest exhibited high specific leaf area. The P. massoniana forest was subjected to N and P colimitation, and the three other broad‐leaved forests were limited by P supply. The community‐weighted means rather than the arithmetic means of traits were preferential to represent the trait characteristics at the community level. From the view of plant functional traits at the community level, karst forests develop multiple functional traits like low specific leaf area, high dry matter content and tissue density of leaf, roots, branch, and twig, and decrease N and P investments in leaf for a conservative survival strategy to adapt to harsh habitats.

IRE-dependent Regulation of Intestinal Dmt1 Prevails During Chronic Dietary Iron Deficiency but is Dispensable in Conditions of Acute Erythropoietic Stress.

IRE-dependent Regulation of Intestinal Dmt1 Prevails During Chronic Dietary Iron Deficiency but is Dispensable in Conditions of Acute Erythropoietic Stress.

Promoting Effect of Soluble Polysaccharides Extracted from Ulva spp. on Zea mays L. Growth.

Seaweeds can play a vital role in plant growth promotion. Two concentrations (5 and 10 mg/mL) of soluble polysaccharides extracted from the green macroalgae Ulva fasciata and Ulva lactuca were tested on Zea mays L. The carbohydrate and protein contents, and antioxidant activities (phenols, ascorbic, peroxidase, and catalase) were measured, as well as the protein banding patterns. The soluble polysaccharides at 5 mg/mL had the greatest effect on the base of all of the parameters. The highest effects of soluble polysaccharides on the Zea mays were 38.453, 96.76, 4, 835, 1.658, 7.462, and 38615.19, mg/mL for carbohydrates, proteins, phenol, µg ascorbic/mL, mg peroxidase/g dry tissue, and units/g tissue of catalase, respectively. The total number of protein bands (as determined by SDS PAGE) was not changed, but the density of the bands was correlated to the treatments. The highest band density and promoting effect were correlated to 5 mg/mL soluble polysaccharide treatments extracted from Ulva fasciata in Zea mays, which can be used as a biofertilizer.

Quantitative Assessment of Asbestos Fibers in Normal and Pathological Pleural Tissue-A Scoping Review.

Background: pleural mesothelioma is a rare cancer in the general population, but it is more common in subjects occupationally exposed to asbestos. Studies with asbestos fiber quantification in pleural tissue are scarce: for this reason, we aimed at undertaking a scoping review to summarize the evidence provided by studies in which asbestos fibers were determined by electron microscopy (SEM or TEM) in human pleural tissues, whether normal or pathologic. Materials and methods: A scoping review of articles that quantified asbestos fibers in human pleural tissue (normal or pathologic) by electron microscopy (SEM or TEM), in subjects with asbestos exposure (if any) was performed. Results: The 12 studies selected comprised 137 cases, out of which 142 samples were analyzed. Asbestos fibers were detected in 111 samples (78%) and were below the detectable limit in 31 samples (22%). The concentration of asbestos fibers detected in the positive samples was distributed from as low as 0.01 mfgdt (millions of fibers per gram of dry tissue) up to 240 mfgdt. However, the minimum concentration of fibers overlaps in the three types of tissues (normal pleura, pleural plaque, mesothelioma) in terms of magnitude; therefore, it is not possible to distinguish a definite pattern which differentiates one tissue from the other. Conclusions: The studies included were heterogeneous as to the representativeness of the samples and analytical techniques; the possibility of false negatives must be considered. It would be desirable to systematically search for asbestos fibers to fill the knowledge gap about the presence of asbestos fibers in normal or pathological pleural tissue in order to better understand the development of the different pleural diseases induced by this mineral.

Mesoscale Simulation-Based Parametric Study of Damage Potential in Brain Tissue Using Hyperelastic and Internal State Variable Models.

Two-dimensional mesoscale finite element analysis (FEA) of a multilayered brain tissue was performed to calculate the damage-related average stress triaxiality and local maximum von Mises strain in the brain. The FEA was integrated with rate-dependent hyperelastic and internal state variable (ISV) models, respectively, describing the behaviors of wet and dry brain tissues. Using the finite element results, a statistical method of design of experiments (DOE) was utilized to independently screen the relative influences of seven parameters related to brain morphology (sulcal width/depth, gray matter (GM) thickness, cerebrospinal fluid (CSF) thickness and brain lobe) and loading/environment conditions (strain rate and humidity) with respect to the potential damage growth/coalescence in the brain tissue. The results of the parametric study illustrated that the GM thickness and humidity were the two most crucial parameters affecting average stress triaxiality. For the local maximum von Mises strain at the depth of brain sulci, the brain lobe/region was the most influential factor. The conclusion of this investigation gives insight for the future development and refinement of a macroscale brain damage model incorporating information from lower length scale.

Bioinspired elastomer composites with programmed mechanical and electrical anisotropies

Concepts that draw inspiration from soft biological tissues have enabled significant advances in creating artificial materials for a range of applications, such as dry adhesives, tissue engineering, biointegrated electronics, artificial muscles, and soft robots. Many biological tissues, represented by muscles, exhibit directionally dependent mechanical and electrical properties. However, equipping synthetic materials with tissue-like mechanical and electrical anisotropies remains challenging. Here, we present the bioinspired concepts, design principles, numerical modeling, and experimental demonstrations of soft elastomer composites with programmed mechanical and electrical anisotropies, as well as their integrations with active functionalities. Mechanically assembled, 3D structures of polyimide serve as skeletons to offer anisotropic, nonlinear mechanical properties, and crumpled conductive surfaces provide anisotropic electrical properties, which can be used to construct bioelectronic devices. Finite element analyses quantitatively capture the key aspects that govern mechanical anisotropies of elastomer composites, providing a powerful design tool. Incorporation of 3D skeletons of thermally responsive polycaprolactone into elastomer composites allows development of an active artificial material that can mimic adaptive mechanical behaviors of skeleton muscles at relaxation and contraction states. Furthermore, the fabrication process of anisotropic elastomer composites is compatible with dielectric elastomer actuators, indicating potential applications in humanoid artificial muscles and soft robots.

Low Temperature Delays Metabolism of Quizalofop in Resistant Winter Wheat and Three Annual Grass Weed Species

Quizalofop-resistant wheat is the core component of the recently commercialized CoAXium™ Wheat Production System. As with other herbicides, quizalofop provides better weed control at early growth stages and under optimum temperature. However, in regions with winter wheat production, quizalofop application may be affected by unpredictable, rapid temperature decreases. Temperature shifts can cause crop injury or impact weed control efficacy. In the following study, we examine the effect of reduced temperature on quizalofop content and metabolism in CoAXium™ winter wheat and three winter weed species: downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), and jointed goatgrass (Aegilops cylindrica Host). Temperature conditions include either 19 or 4.5°C daytime temperatures with tissue sampling over 5 timepoints (1–16 or 18 days after treatment, DAT). Analysis features liquid chromatography coupled to tandem mass spectrometry detection of the active form of quizalofop, quizalofop acid. Quizalofop content trends reveal delayed metabolism under cooler conditions for wheat and weeds. Quizalofop content peaks within 1–2 DAT in the warmer temperatures for all species and decreases thereafter. In contrast, content peaks between 8 and 9 DAT at cooler temperatures except for downy brome. Minimal decreases in content over time generally follow cooler temperature peaks. Further, the absence of differences in maximum quizalofop content in all species suggests absorption and/or de-esterification of quizalofop proherbicide to the active form is not reduced at cooler temperatures. Final dry shoot tissue biomass does not necessarily correspond to differences in metabolism, as biomass of wheat treated with a field rate of quizalofop does not differ between temperatures. Weeds were treated with sublethal doses of quizalofop in order to monitor herbicide metabolism without causing plant death. Under this condition, weed biomass only differs for jointed goatgrass, which has a greater biomass in the cooler temperature.

In situ metabolic profile and spatial distribution of ocular tissues: New insights into dry eye disease

PurposeDry eye disease (DED) is a chronic multifactorial disorder affecting millions of people, yet the pathogenesis mechanisms still remain unclear. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) is a novel in situ visualization approach combined high-throughput mass spectrometry and molecular imaging. We aimed to explore the in situ ocular metabolic changes via MALDI-MSI to accelerate the recognition of DED pathogenesis. MethodsExperimental dry eye was established in Wistar rats by subcutaneous injection of scopolamine. The induction of DED was assessed by tear film breakup time, sodium fluorescein, histopathological staining and cell apoptosis. MALDI-MSI was applied to explore in situ ocular metabolomic in DED rats, and histopathological staining from same sections were used for side-by-side comparison with MALDI to annotate different tissue structures in the eye. ResultsConsidering the complexity of ocular tissue, we visualized the metabolites in specific ocular regions (central cornea, peripheral cornea, fornix conjunctiva, eyelid conjunctiva and aqueous humor), and identified metabolites related to DED, with information of relative abundance and spatial signatures. In addition, integrative pathway analysis illustrated that, several metabolic pathways such as glycerophospholipid, sphingolipid phenylalanine, and metabolism of glycine, serine and threonine were significantly altered in certain regions in the dry eye tissue. Moreover, we discussed how the metabolic pathways with spatiotemporal signatures might be involved in the DED process. ConclusionsOur data exploit the advantages of in situ analysis of MALDI-MSI to accurately analyze the region-specific metabolic behaviors in DED, and provide new clues to uncover DED pathogenesis.

Optimization of Complete Rat Heart Decellularization Using Artificial Neural Networks.

Whole organ decellularization techniques have facilitated the fabrication of extracellular matrices (ECMs) for engineering new organs. Unfortunately, there is no objective gold standard evaluation of the scaffold without applying a destructive method such as histological analysis or DNA removal quantification of the dry tissue. Our proposal is a software application using deep convolutional neural networks (DCNN) to distinguish between different stages of decellularization, determining the exact moment of completion. Hearts from male Sprague Dawley rats (n = 10) were decellularized using 1% sodium dodecyl sulfate (SDS) in a modified Langendorff device in the presence of an alternating rectangular electric field. Spectrophotometric measurements of deoxyribonucleic acid (DNA) and total proteins concentration from the decellularization solution were taken every 30 min. A monitoring system supervised the sessions, collecting a large number of photos saved in corresponding folders. This system aimed to prove a strong correlation between the data gathered by spectrophotometry and the state of the heart that could be visualized with an OpenCV-based spectrometer. A decellularization completion metric was built using a DCNN based classifier model trained using an image set comprising thousands of photos. Optimizing the decellularization process using a machine learning approach launches exponential progress in tissue bioengineering research.

MODERN DIAGNOSTIC CRITERION FOR ESTABLISHING THE REGIONAL ORIGIN OF BLOOD IN SEXUAL CRIMES

The aim: Determination of regional blood origin in cases of sexual violence, establishing the possibility of using prostaglandin F2alpha as a marker of blood of menstrual origin. Materials and methods: The material for the study were samples of vaginal fluid, menstrual blood and capillary blood from females, the age distribution of women was carried out according to the gynecological classification according to the age periods of women’s lives depending on the functional state of their reproductive system: the first group – women at the age of 18-29, the second group – women at the age of 30-45. Results: Among objects of biological origin, fluids, especially blood, occupy an important place. The content of PGF2α has age fluctuations: its content is higher by 6-12% in women aged 30-45 than in women 18-29 years old. PGF2α levels above 13.1 ng / mg of dry tissue are a reliable sign of blood of menstrual origin, which is very important in determining the regional origin of blood in forensic examinations for sexual violence / sexual crimes. Conclusions: In cases of sexual violence against women, in addition to recording external harm, attention should also be paid to the examination of objects of biological origin, identification by species, sex, regional, organ or cell.

Determination of the order of damage to a cotton cloth moistened with water when fired from a Glock 17 pistol

BACKGROUND: To determine the order of the shot from a firearm, the presence of soot deposits and additional factors of the shot on the surface of the fabric is investigated. These signs were detected and tested on dry targets, but not studied on a wet target. There is no data in the available literature that allows determining the order of a shot on a water-soaked target. AIMS: To identify morphological differences between gunshot wounds of dry and water-soaked tissue. MATERIAL AND METHODS: For the experiment, a target object made of cotton calico was used; a Glock 17 pistol; 919 Parabellum cartridges. There were two groups of targets ― moistened with running water from a spray gun and dry. After impregnation, the fabric was hung in a vertical position on a thick cardboard substrate, and then a shot was fired. The firearm (Glock 17) was fixed on the frame, the muzzle end was directed towards the target at an angle of 90. Shots were fired from a distance of 5 cm, 10 cm, 20 cm and further in increments of 10 cm to 100 cm inclusive. At each distance, 10 shots were fired, from which 3 targets were selected that had the most pronounced morphological changes: thermally altered fibers on the front surface of the target, along the edge of the gunshot injury, along the depth of penetration of the wiping belt. After that, the barrel of the firearm was cleaned. The study of the affected targets was carried out using a Leica M125 stereomicroscope. The results obtained during the experiment were entered into the MS Excel table where statistical processing was performed. A conditional probability was calculated for each feature. The diagnostic coefficient (DC) was calculated, and the Kulbak formula was used to assess the informativeness of the selected features. RESULTS: It was revealed that signs of thermal action and the deposition of soot on the front side of the target are found on dry targets. Thermally altered filaments were not detected on wet targets, and the products of the shot penetrate the inter-fiber space. The thermal effect is manifested by the formation of flask-like and hemp-like endings of the fibers of the threads along the edge of the gunshot injury. CONCLUSION: The detection of signs of thermal exposure, as well as the deposition of soot only on the front surface of the target, suggests that the shot was fired into a dry cloth. Penetration of the products forming the metallization belt into the inter-fiber space, as well as the absence of thermally altered threads, is characteristic of gunshot damage to wet targets. Described changes in the protocol for registration of morphological lesions in the presence of an expert. The results of this study provide a better situational expertise.

Decellularised human bone allograft from different anatomical sites as a basis for functionally stratified repair material for bone defects

Tissue engineered bone solutions aim to overcome the limitations of autologous and allogeneic grafts. Decellularised tissues are produced by washing cellular components from human or animal tissue to produce an immunologically safe and biocompatible scaffold, capable of integration following implantation. A decellularisation procedure utilising low concentration sodium dodecyl sulphate (0.1% w/v) was applied to trabecular bone from human femoral heads (FH) and tibial plateaus (TP). Biological (histology, DNA quantification), biomechanical (compression testing) and structural (μCT) comparisons were made between decellularised and unprocessed cellular tissue. Total DNA levels of decellularised FH and TP bone were below 50 ng·mg-1 dry tissue weight and nuclear material was removed. No differences were found between cellular and decellularised bone, from each anatomical region, for all the biomechanical and structural parameters investigated. Differences were found between cellular FH and TP and between decellularised FH and TP. Decellularised FH had a higher ultimate compressive stress, Young's modulus and 0.2% proof stress than decellularised TP (p = 0.001, 0.002, 0.001, Mann Whitney U test, MWU). The mineral density of cellular and decellularised TP bone was significantly greater than cellular and decellularised FH bone respectively (cellular: p = 0.001, decellularised: p < 0.001, MWU). The bone volume fraction and trabecular thickness of cellular and decellularised FH bone were significantly greater than cellular and decellularised TP bone respectively (cellular: p = 0.001, 0.005; decellularised: p < 0.001, <0.001, MWU). Characterisation of decellularised trabecular bone from different anatomical regions offers the possibility of product stratification, allowing selection of biomechanical properties to match particular anatomical regions undergoing bone graft procedures.

On the uptake of rhenium by plants: Accumulation and recovery from plant tissue

Rhenium (Re) is one of the scarcest and more broadly dispersed elements on Earth. Due to its paucity and high demand by the aerospace and petroleum industries, it is also one of the most valuable metals in the international market. In recent years, reports about the occurrence of Re in soils surrounding copper-molybdenum mines and its uptake by the local vegetation have fueled research on the feasibility of Re phytomining. Still, the mechanisms of Re accumulation and its potential retrieval from plant tissue have not been elucidated. Hence, in this work, infrared (IR) spectrometry and scanning electron microscopy (SEM) analysis were employed for the first time to assess how rhenium is accumulated in plants. Moreover, we have proposed a simple methodology based on dry leaf tissue disruption and water rising for recovering Re. The process was tested on the glasshouse-grown alfalfa plants and field samples (Acacia, white clover, and grass) collected in the vicinity of the Assarel-Medet copper mine (Bulgaria), where soil Re levels are high. Our findings demonstrate that following root absorption and translocation, Re was stored in the vacuoles of alfalfa leaf cells as water-soluble potassium perrhenate (KReO4). The solubility of the leaf stored Re compounds was further demonstrated by the proposed aqueous extraction procedure, as mixing 1 g of dry leaf in 30 mL of distilled water during 30 min sufficed to achieve almost complete Re recovery in the ensuing leachates of alfalfa (99.82%), Acacia (97.95%), white clover (99.15%), and grass (99.05%). Although additional research is necessary to confirm the effectiveness and practicability of the proposed Re retrieval at field scale, this study may prove instrumental to increase the economic and environmental viability of Re phytomining.

A Validated Ultrasound-Assisted Extraction Coupled with SPE-HPLC-DAD for the Determination of Flavonoids in By-Products of Plant Origin: An Application Study for the Valorization of the Walnut Septum Membrane.

Walnut byproducts have been shown to exert functional properties, but the literature on their bioactive content is still scarce. Among walnut byproducts, walnut septum is a dry ligneous diaphragm tissue that divides the two halves of the kernel, exhibiting nutritional and medicinal properties. These functional properties are owing to its flavonoid content, and in order to explore the flavonoid fraction, an ultrasound-assisted (UAE) protocol was combined with solid phase extraction (SPE) and coupled to high-performance liquid chromatography with diode array detection (HPLC-DAD) for the determination of flavonoids in Greek walnut septa membranes belonging to Chandler, Vina, and Franquette varieties. The proposed UAE-SPE-HPLC-DAD method was validated and the relative standard deviations (RSD%) of the within-day and between-day assays were lower than 6.2 and 8.5, respectively, showing good precision, and high accuracy ranging from 90.8 (apigenin) to 97.5% (catechin) for within-day assay, and from 88.5 (myricetin) to 96.2% (catechin) for between-day assay. Overall, seven flavonoids were determined (catechin, rutin, myricetin, luteolin, quercetin, apigenin, and kaempferol) suggesting that the walnut septum is a rich source of bioactive constituents. The quantification results were further processed using ANOVA analysis to examine if there are statistically significant differences between the concentration of each flavonoid and the variety of the walnut septum.

Hoornvliesbeschadiging na cataractchirurgie: belang van het droge-ogensyndroom en topische NSAID’s en oppuntstelling van de behandeling

Dry eye disease and cataract surgery: identification of risk factors for corneal damage and optimisation of treatment Various factors in the perioperative cataract surgery period can synergistically initiate a vicious inflammatory cycle of dry eye disease (DED) and tissue damage, with dire consequences. A careful anamnesis and preoperative assessment of the ocular surface can reveal some of the risk factors and facilitate an appropriate perioperative approach. Attention should be paid to DED and associated conditions, such as Meibomian gland dysfunction, as these conditions are very common. In the postoperative period, it is wise to avoid preserved topical medication, as well as to use topical medication that may be toxic to the ocular surface, such as non-steroidal anti-inflammatory drugs (NSAIDs), with care in specific cases. The treatment of DED and its complications consists primarily of the careful use of lubricating, antibiotic and anti-inflammatory agents. In serious DED cases, autologous serum promotes tissue regeneration by promoting epithelialisation and stromal recovery, and can be a useful adjunct to the first-line treatment. In extreme and rare cases, DED can, in combination with the use of topical NSAIDs and other risk factors, lead to sight-threatening complications, such as corneal melting. A surgical treatment consisting of conjunctival flap transplantation, amniotic membrane transplantation, gluing of the cornea or tectonic keratoplasty may be necessary when perforation is imminent.

Ulva compressa from Copper-Polluted Sites Exhibits Intracellular Copper Accumulation, Increased Expression of Metallothioneins and Copper-Containing Nanoparticles in Chloroplasts.

In order to analyze the mechanisms involved in copper accumulation in Ulva compressa, algae were collected at control sites of central and northern Chile, and at two copper-polluted sites of northern Chile. The level of intracellular copper, reduced glutathione (GSH), phytochelatins (PCs), PC2 and PC4, and transcripts encoding metallothioneins (MTs) of U. compressa, UcMT1, UcMT2 and UcMT3, were determined. Algae of control sites contained around 20 g of copper g−1 of dry tissue (DT) whereas algae of copper-polluted sites contained 260 and 272 g of copper g−1 of DT. Algae of control sites and copper-polluted sites did not show detectable amounts of GSH, the level of PC2 did not change among sites whereas PC4 was increased in one of the copper-polluted sites. The level of transcripts of UcMT1 and UcMT2 were increased in algae of copper-polluted sites, but the level of UcMT3 did not change. Algae of a control site and a copper-polluted site were visualized by transmission electron microscopy (TEM) and the existence of copper in electrodense particles was analyzed using energy dispersive x-ray spectroscopy (EDXS). Algae of copper-polluted sites showed electrodense nanoparticles containing copper in the chloroplasts, whereas algae of control sites did not. Algae of a control site, Cachagua, were cultivated without copper (control) and with 10 M copper for 5 days and they were analyzed by TEM-EDXS. Algae cultivated with copper showed copper-containing nanoparticles in the chloroplast whereas control algae did not. Thus, U. compressa from copper-polluted sites exhibits intracellular copper accumulation, an increase in the level of PC4 and expression of UcMTs, and the accumulation of copper-containing particles in chloroplasts.

On the discrimination between facial creams of different brands using Raman Spectroscopy and partial least squares discriminant analysis for forensic application

Determining the origin of cosmetic traces is an important aspect of forensic investigations, that helps linking a suspect to a crime. Such type of evidence can help further narrow down the undergoing investigations. This paper reports the first use of Raman Spectroscopy (RS) coupled with the exploratory principal component analysis (PCA) and supervised partial least squares-discriminant analysis (PLS-DA) in facial creams. 40 facial cream samples of 8 different brands were studied in this work. Preliminary assessments through visual inspection of their Raman spectra revealed the presence of oxides, titanium dioxide, castor seed oil, and beeswax. Also, the peaks of alkyne groups were indicative of the presence of talc or mica compounds. The exploratory PCA correctly segregated the samples into 8 clusters and the supervised PLS-DA model correctly classified them into 8 classes. Further evaluation of the performance of the trained PLS-DA model resulted in perfect classification shown by the receiver operating characteristic (ROC) curves. The PLS-DA model also resulted in 100% accuracy of correctly assigning the brand on the face wipes on each of the five substrates viz. cotton, dry and wet tissue paper, nylon substrate, and polyester. This validation was done treating these samples as unknowns. The study has a potential for use under actual forensic casework conditions.

Sesamum indicum Oleosin L improves oil packaging in Nicotiana benthamiana leaves.

Plant oil production has been increasing continuously in the past decade. There has been significant investment in the production of high biomass plants with elevated oil content. We recently showed that the expression of Arabidopsis thaliana WRI1 and DGAT1 genes increase oil content by up to 15% in leaf dry weight tissue. However, triacylglycerols in leaf tissue are subject to degradation during senescence. In order to better package the oil, we expressed a series of lipid droplet proteins isolated from bacterial and plant sources in Nicotiana benthamiana leaf tissue. We observed further increases in leaf oil content of up to 2.3‐fold when we co‐expressed Sesamum indicum Oleosin L with AtWRI1 and AtDGAT1. Biochemical assays and lipid droplet visualization with confocal microscopy confirmed the increase in oil content and revealed a significant change in the size and abundance of lipid droplets.

Conocimientos y actitudes de los profesores de nivel preescolar sobre el trauma dental en Rijeka, Croacia: un estudio transversal.

Introduction: Traumatic tooth injuries often occur in childhood. They are not life-threatening, but they can cause a number of complications that can affect the quality of life. Proper first aid can significantly facilitate further dental treatment. The aim of this research was to evaluate preschool teachers’ knowledge and attitudes about dental trauma and their motivation for further education. Material and Methods: This cross-sectional study included 54 preschool teachers. It was carried out in the form of a questionnaire consisting of 23 questions regarding traumatic tooth injuries, experiences and knowledge and teachers’ interest in additional education.Results: Most of the preschool teachers, 68.51%, did not witness any dental traumas during their work experience. From the teachers who witnessed dental trauma, only 11.76% gave first aid and none of them called the dentist and followed their instructions. In case of dental avulsion 72.22% would keep the avulsed tooth in a dry gauze or tissue. Even though 81.49% consider themselves uninformed about dental, all of them are interested in additional education. Conclusion: Despite the insufficient knowledge about dental trauma, its management, and first aid it is encouraging that all of the preschool teachers included in this research are motivated to educate themselves more on this subject.

Impact of Intertidal Distribution on the Physiological Performance of the Filter-Feeder Bivalve Perumytilus purpuratus (Bivalvia, Mytilidae) from Southern Chile

Intertidal animals experience reduced feeding times and differentiated respiratory capacity associated with aerial exposure, the duration of which depends on their location within the intertidal zone. Perumytilus purpuratus is a sessile mussel that forms dense mats in the rocky mid-intertidal in southern Chile. For this species, we documented the impact of different times of aerial exposure (3 and 6 h) on rates of oxygen consumption and feeding, according to their vertical location (upper and lower limits) within the intertidal zone. Mean oxygen consumption rates in air for individuals located in the upper intertidal zone were 52% higher than those of individuals located at the lower limits of their intertidal distribution. Additionally, individuals from the lower intertidal region always presented higher rates of oxygen consumption and particle clearance rates (58% higher and 18% higher, respectively) during immersion compared to individuals collected from the upper limit of their intertidal distribution, regardless of the duration of previous aerial exposure. Although we found no significant habitat-related differences in the relationship between shell length and gill surface area, individuals sampled from the lower intertidal zone were 8% heavier in dry tissue weight than individuals with the same shell lengths collected from of the upper limit of their intertidal distribution. Our results suggest that the individuals of this species near the upper limits of their intertidal distribution can probably compensate (e.g., higher absorption rate) for the reduced time that they have available for clearance, which might help them to avoid a major energetic disadvantage.