International Volunteer Programs for Dental Students: Results of 2009 and 2016 Surveys of U.S. Dental Schools

The aims of this study were to determine the prevalence and nature of international volunteer programs for predoctoral students at U.S. dental schools and to document the change over five years. Web-based surveys were conducted in 2009 and 2016. An invitation to participate in the study, along with a hyperlink to the survey, was emailed to the deans of all U.S. dental schools in the two years. In 2009, 47 of 58 dental school deans responded to the survey, for a response rate of 81%. In 2016, 48 of 64 dental school deans responded, for a response rate of 75%. From 2009 to 2016, the number of schools reporting dental student international experiences increased from 25 to 31. In 2016, 65% of responding schools offered dental student international experiences, an 11.5% increase over the results of the 2009 survey. Concomitantly, the number of deans reporting their students' participation in international opportunities not officially sanctioned by the school decreased from 41 to 34. These findings showed an increase in the number of dental schools providing international experiences for their students and established baseline data to assess trends in the future

The impact of malaria parasites on dendritic cell–T cell interaction

Malaria is caused by apicomplexan parasites of the genus Plasmodium. While infection continues to pose a risk for the majority of the global population, the burden of disease mainly resides in Sub-Saharan Africa. Although immunity develops against disease, this requires years of persistent exposure and is not associated with protection against infection. Repeat infections occur due to the parasite's ability to disrupt or evade the host immune responses. However, despite many years of study, the mechanisms of this disruption remain unclear. Previous studies have demonstrated a parasite-induced failure in dendritic cell (DCs) function affecting the generation of helper T cell responses. These T cells fail to help B cell responses, reducing the production of antibodies that are necessary to control malaria infection. This review focuses on our current understanding of the effect of Plasmodium parasite on DC function, DC-T cell interaction, and T cell activation. A better understanding of how parasites disrupt DC-T cell interactions will lead to new targets and approaches to reinstate adaptive immune responses and enhance parasite immunity

Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (lvtESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wustite (lW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at I GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850 C. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-Si02 buffer, which is approx. 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi206) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of the fate of elements during the differentiation and thermal evolution of Mercury and other highly reducing planetary bodies

Impact of mid-to-late Holocene precipitation changes on vegetation across lowland tropical South America: a palaeo-data synthesis

A multi-proxy paleo-data synthesis of 110 sites is presented, exploring the impact of mid-to-late Holocene precipitation changes upon vegetation across Southern Hemisphere tropical South America. We show that the most significant vegetation changes occurred in south-west Amazonia and south-east Brazil, regions reliant on precipitation derived from the South American summer monsoon (SASM). A drier mid Holocene in these regions, linked to a weaker SASM, favoured more open vegetation (savannah/grasslands) than present, while increased late-Holocene precipitation drove expansion of humid forests (e.g. evergreen tropical forest in south-west Amazonia, Araucaria forests in south-east Brazil). The tropical forests of central, western and eastern Amazonia remained largely intact throughout this 6000-year period. North-eastern Brazil's climate is 'antiphased' with the rest of tropical South America, but a lack of paleo data limits our understanding of how vegetation responded to a wetter(drier) mid(late) Holocene. From this paleo-data perspective, we conclude that ecotonal forests already close to their climatic thresholds are most vulnerable to predicted future drought, but the forest biome in the core of Amazonia is likely to be more resilient. Of greater concern is widespread deforestation and uncontrolled anthropogenic burning, which will decrease ecosystem resilience, making them more vulnerable than they might be without current anthropogenic pressures

Heavy metals, biomarkers of oxidative stress and changes in sperm function: A case-control study

Background: Heavy metal-induced oxidative stress has been implicated in abnormal sperm functions and male infertility. Objective: Serum and seminal levels of heavy metals and biomarkers of oxidative stress were compared in fertile and infertile men. Materials and Methods: A total of 130 men aged 20–60 yr comprising 30 azoospermic, 50 oligozoospermic, and 50 normozoospermic men were studied. Semen analysis was done by world health organization guidelines, biomarkers of oxidative stress (total antioxidant capacity (TAC), total plasma peroxidase (TPP), oxidative stress index (OSI), vitamin C (vit C) and nitric oxide (NO)) and fructose by colorimetry and serum and seminal heavy metals (zinc (Zn), selenium (Se), cadmium (Cd) and lead (Pb)) by atomic absorption spectrophotometry. Results: Azoospermic and oligozoospermic men had higher serum and seminal peroxides (TPP, p = 0.00), higher serum heavy metals (Zn, Se, Pb, and Cd (p = 0.01)) and lower sperm concentration, %motility, serum and seminal antioxidants (vit C, TAC, NO, GSH (p = 0.01)) compared to normozoospermic men. Higher seminal peroxides (TPP, p = 0.001), heavy metals (Pb and Cd (p = 0.03)) and lower sperm concentration, %motility, and seminal antioxidants (TAC and NO (p = 0.00)) were also observed in azoospermic men compared to oligozoospermic men. Negative correlations were observed between seminal fructose and seminal vit C (r = -0.535, p = 0.015), GSH (r =-0.734, p = 0.000), NO (r = -0.714, p = 0.000), Zn (r = -0.774, p = 0.000) and Se (r = -0.719, p = 0.000) only in azoospermic men. Conclusion: Elevated heavy metal levels, increased lipid peroxidation and antioxidant depletion is associated with abnormal sperm functions in men studied. Key words: Heavy metals, Antioxidants, Lipid peroxidation, Oxidative stress, Sperm function

Association of intracellular and synaptic organization in cochlear inner hair cells revealed by 3D electron microscopy

The ways in which cell architecture is modelled to meet cell function is a poorly understood facet of cell biology. To address this question, we have studied the cytoarchitecture of a cell with highly specialised organisation, the cochlear inner hair cell (IHC), using multiple hierarchies of 3D electron microscopy analyses. We show that synaptic terminal distribution on the IHC surface correlates with cell shape, and the distribution of a highly organised network of membranes and mitochondria encompassing the infranuclear region of the cell. This network is juxtaposed to a population of small vesicles and represents a potential new source of neurotransmitter vesicles for replenishment of the synapses. Structural linkages between organelles that underlie this organisation were identified by high resolution imaging. Together these results describe a cell-encompassing network of membranes and mitochondria present in IHCs which support efficient coding and transmission of auditory signals. Such techniques also have the potential for clarifying functionally specialised cytoarchitecture of other cell types

Joint ESPGHAN/NASPGHAN Guidelines for the Management of Helicobacter pylori in Children and Adolescents ( Update 2016)

Background: Because of the changing epidemiology of Helicobacter pylori infection and low efficacy of currently recommended therapies, an update of the European Society for Paediatric Gastroenterology Hepatology and Nutrition/North American Society for Pediatric Gastroenterology, Hepatology and Nutrition recommendations for the diagnosis and management of H pylori infection in children and adolescents is required. Methods: Asystematic review of the literature (time period: 2009-2014) was performed. Representatives of both societies evaluated the quality of evidence using GRADE (Grading of Recommendation Assessment, Development, and Evaluation) to formulate recommendations, which were voted upon and finalized using a Delphi process and face-to-face meeting. Results: The consensus group recommended that invasive diagnostic testing for Hpylori be performed only when treatment will be offered if tests are positive. To reach the aim of a 90% eradication rate with initial therapy, antibiotics should be tailored according to susceptibility testing. Therapy should be administered for 14 days, emphasizing strict adherence. Clarithromycin-containing regimens should be restricted to children infected with susceptible strains. When antibiotic susceptibility profiles are not known, high-dose triple therapy with proton pump inhibitor, amoxicillin, and metronidazole for 14 days or bismuth-based quadruple therapy is recommended. Success of therapy should be monitored after 4 to 8 weeks by reliable noninvasive tests. Conclusions: The primary goal of clinical investigation is to identify the cause of upper gastrointestinal symptoms rather than H pylori infection. Therefore, we recommend against a test and treat strategy. Decreasing eradication rates with previously recommended treatments call for changes to first-line therapies and broader availability of culture or molecular-based testing to tailor treatment to the individual child

Developing the role of Earth observation in spatio-temporal mosquito modelling to identify malaria hot-spots

Anopheles mosquitoes are the vectors of human malaria, a disease responsible for a significant burden of global disease and over half a million deaths in 2020. Here, methods using a time series of cost-free Earth Observation (EO) data, 45,844 in situ mosquito monitoring captures, and the cloud processing platform Google Earth Engine are developed to identify the biogeographical variables driving the abundance and distribution of three malaria vectors—Anopheles gambiae s.l., An. funestus, and An. paludis—in two highly endemic areas in the Democratic Republic of the Congo. EO-derived topographical and time series land surface temperature and rainfall data sets are analysed using Random Forests (RFs) to identify their relative importance in relation to the abundance of the three mosquito species, and they show how spatial and temporal distributions vary by site, by mosquito species, and by month. The observed relationships differed between species and study areas, with the overall number of biogeographical variables identified as important in relation to species abundance, being 30 for An. gambiae s.l. and An. funestus and 26 for An. paludis. Results indicate rainfall and land surface temperature to consistently be the variables of highest importance, with higher rainfall resulting in greater mosquito abundance through the creation of pools acting as mosquito larval habitats; however, proportional coverage of forest and grassland, as well as proximity to forests, are also consistently identified as important. Predictive application of the RF models generated monthly abundance maps for each species, identifying both spatial and temporal hot-spots of high abundance and, by proxy, increased malaria infection risk. Results indicate greater temporal variability in An. gambiae s.l. and An. paludis abundances in response to seasonal rainfall, whereas An. funestus is generally more temporally stable, with maximum predicted abundances of 122 for An. gambiae s.l., 283 for An. funestus, and 120 for An. paludis. Model validation produced R2 values of 0.717 for An. gambiae s.l., 0.861 for An. funestus, and 0.448 for An. paludis. Monthly abundance values were extracted for 248,089 individual buildings, demonstrating how species abundance, and therefore biting pressure, varies spatially and seasonally on a building-to-building basis. These methods advance previous broader regional mosquito mapping and can provide a crucial tool for designing bespoke control programs and for improving the targeting of resource-constrained disease control activities to reduce malaria transmission and subsequent mortality in endemic regions, in line with the WHO’s ‘High Burden to High Impact’ initiative. The developed method was designed to be widely applicable to other areas, where suitable in situ mosquito monitoring data are available. Training materials were also made freely available in multiple languages, enabling wider uptake and implementation of the methods by users without requiring prior expertise in EO

Morphometry of subaerial shield volcanoes and glaciovolcanoes from Reykjanes Peninsula, Iceland: Effects of eruption environment

We present a morphometric study of 33 basaltic volcanic edifices from the Reykjanes Peninsula, Iceland, using a 20 m resolution digital elevation model (DEM). Slope values distinguish subaerial from intraglacial eruption environments, with glaciovolcanic edifices having average slope values that are > 5° higher than subaerial shields. The 26 analyzed glaciovolcanic edifices are separated into 3 groups based on size, and are also categorized following the new classification scheme of tuyas by Russell et al. (2014), into 15 tindars, 1 conical tuya, 3 flat-topped tuyas and 7 complex tuyas. The glaciovolcanic edifices show a continuum of landforms ranging from small elongated tindars to large equidimensional flat-topped tuyas. The smaller edifices ( 0.1 km3) are flat-topped tuyas. The mid-sized edifices (0.01–0.1 km3) show a wide variety of shapes and classify either as tindars or as complex tuyas, with only one edifice classifying as a conical tuya. Edifice elongation tends to decrease with volume, suggesting that small edifices are primarily fissure controlled, whereas larger edifices are mainly controlled by a central vent. The mid-sized complex tuyas are transitional edifices, suggesting that some intraglacial eruptions start as fissure eruptions that subsequently concentrate into one or more central vents, whereas the mid-sized tindars suggest a sustained fissure eruption. There is a tectonic control on the orientation of the edifices evidenced by a strong correlation between edifice elongation azimuth and mapped faults and fractures. Most edifice elongations cluster between 020° and 080°, coinciding with the strike of normal faults within and at the boundary of regional volcanic systems, but some edifices have elongations that correlate with N–S striking book-shelf faults. This implies that intraglacial eruptions are controlled by pre-existing pathways in the crust, as has been previously observed for subaerial fissure eruptions. In terms of classification, quantification of the limits between the four tuya types proposed by Russell et al. (2014) is difficult because of the transitional nature shown by several edifices. A threshold of 1.8 in ellipticity index (E.I.) values can be used to distinguish tindars from the other three types. Flat-topped tuyas are distinguished by their greater overall size, their large and relatively flat summit regions, reflected in bimodal slope distributions, and their low E.I. and low to intermediate irregularity index (I.I.) values. The only analyzed conical tuya has very low E.I. and I.I. values, very small summit regions and very steep flank slopes. The complex tuyas have variable morphometries, but are in general characterized by high I.I. values and very irregular slope distributions. No correlation is observed between edifice-scale morphology and lithology (e.g. pillow dominated or hyaloclastite dominated).Fil: Pedersen, G. B. M.. University of Iceland. Institute of Earth Sciences. Nordic Volcanological Center; IslandiaFil: Grosse, Pablo. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentin

Ten Simple Rules for Organizing an Unconference

This is an open access article distributed under the terms of the Creative Commons Attribution License.Peer Reviewe