Exposure to the Dental Environment and Prevalence of Respiratory Illness in Dental Student Populations

Objective: To determine if the prevalence of respiratory disease among dental students and dental residents varies with their exposure to the clinical dental environment. Methods: A detailed questionnaire was administered to 817 students at 3 dental schools. The questionnaire sought information concerning demographic characteristics, school year, exposure to the dental environment and dental procedures, and history of respiratory disease. The data obtained were subjected to bivariate and multiple logistic regression analysis. Results: Respondents reported experiencing the following respiratory conditions during the previous year: asthma (26 cases), bronchitis (11 cases), chronic lung disease (6 cases), pneumonia (5 cases) and streptococcal pharyngitis (50 cases). Bivariate statistical analyses indicated no significant associations between the prevalence of any of the respiratory conditions and year in dental school, except for asthma, for which there was a significantly higher prevalence at 1 school compared to the other 2 schools. When all cases of respiratory disease were combined as a composite variable and subjected to multivariate logistic regression analysis controlling for age, sex, race, dental school, smoking history and alcohol consumption, no statistically significant association was observed between respiratory condition and year in dental school or exposure to the dental environment as a dental patient. Conclusion: No association was found between the prevalence of respiratory disease and a student\u27s year in dental school or previous exposure to the dental environment as a patient. These results suggest that exposure to the dental environment does not increase the risk for respiratory infection in healthy dental health care workers

Human APOER2 isoforms have differential cleavage events and synaptic properties

Human APOER2 is a type I transmembrane protein with a large extracellular domain (ECD) and a short cytoplasmic tail. APOER2-ECD contains several ligand binding domains (LBD) that are organized into exons with aligning phase junctions, which allows for in-frame exon cassette splicing events. We have identified 25 human APOER2 isoforms from cerebral cortex using gene-specific APOER2 primers, where the majority are exon-skipping events within the N-terminal LBD regions in comparison to 6 identified in the heart. APOER2 undergoes proteolytic cleavage in response to ligand binding that releases a C-terminal fragment (CTF) and transcriptionally active intracellular domain (ICD). We therefore tested whether the diversity of human brain-specific APOER2 variants affects APOER2 cleavage. We found exclusion of different ligand binding repeats from splicing generated different amounts of CTFs compared to full-length APOER2 (APOER2-FL). Specifically, APOER2 isoforms lacking exons 5-8 (Δex5-8) and lacking exons 4-6 (Δex4-6) generated the highest and lowest amounts of CTF generation respectively in response to APOE peptide compared to APOER2-FL. The differential CTF generation of APOER2 Δex5-8 and Δex4-6 coincides with the proteolytic release of the ICD which mediates transcriptional activation facilitated by the Mint1 adaptor protein. Functionally, we demonstrated loss of mouse Apoer2 decreased miniature event frequency in excitatory synapses suggesting that Apoer2 is required for spontaneous neurotransmitter release in mature neurons. Lentiviral rescue with human APOER2-FL or Δex4-6 isoform in Apoer2 knockout neurons fully restored the miniature event frequency but not Δex5-8 isoform. These results suggest that human APOER2 isoforms have differential cleavage events and synaptic properties.R01 AG059762 - NIA NIH HHSFirst author draf

Effect of Salts on the Co-Fermentation of Glucose and Xylose by a Genetically Engineered Strain of Saccharomyces Cerevisiae.

Background A challenge currently facing the cellulosic biofuel industry is the efficient fermentation of both C5 and C6 sugars in the presence of inhibitors. To overcome this challenge, microorganisms that are capable of mixed-sugar fermentation need to be further developed for increased inhibitor tolerance. However, this requires an understanding of the physiological impact of inhibitors on the microorganism. This paper investigates the effect of salts on Saccharomyces cerevisiae 424A(LNH-ST), a yeast strain capable of effectively co-fermenting glucose and xylose. Results In this study, we show that salts can be significant inhibitors of S. cerevisiae. All 6 pairs of anions (chloride and sulfate) and cations (sodium, potassium, and ammonium) tested resulted in reduced cell growth rate, glucose consumption rate, and ethanol production rate. In addition, the data showed that the xylose consumption is more strongly affected by salts than glucose consumption at all concentrations. At a NaCl concentration of 0.5M, the xylose consumption rate was reduced by 64.5% compared to the control. A metabolomics study found a shift in metabolism to increased glycerol production during xylose fermentation when salt was present, which was confirmed by an increase in extracellular glycerol titers by 4 fold. There were significant differences between the different cations. The salts with potassium cations were the least inhibitory. Surprisingly, although salts of sulfate produced twice the concentration of cations as compared to salts of chloride, the degree of inhibition was the same with one exception. Potassium salts of sulfate were less inhibitory than potassium paired with chloride, suggesting that chloride is more inhibitory than sulfate. Conclusions When developing microorganisms and processes for cellulosic ethanol production, it is important to consider salt concentrations as it has a significant negative impact on yeast performance, especially with regards to xylose fermentation

Human Pluripotent Stem Cells Serve as an Effective In Vitro Model for Studies of Early Stages of Retinogenesis

poster abstractSpecification of the neural retina is one of the first events in human development and thus, efforts to study the initial stages of retinal specification have been largely limited. This is particularly true for the earliest event in retinogenesis, the establishment of a definitive retinal fate from a more primitive neural progenitor source. With the advent of human pluripotent stem cells (hPSCs), the complex interplay of transcription factors involved in early events of retinal development from an unspecified pluripotent population can be studied in an in vitro model. To examine this potential, hPSCs were directed to differentiate to a neuroretinal lineage in which a subpopulation of cells adopts a definitive retinal fate whereas others develop toward a forebrain lineage. Samples were collected over the first month of differentiation, starting from the undifferentiated state through when cells acquired either retinal or nonretinal forebrain identities and gene expression patterns were characterized using immunocytochemistry and quantitative RT-PCR. Results demonstrated that while neural transcription factors such as PAX6, OTX2, and LHX2 were expressed early in development, definite retinal transcription factors such as CHX10 were expressed later in differentiation. Furthermore, the expression of CHX10 was found to be uniquely associated with retinal populations and remained absent from the other neural populations, thereby illustrating the ability of this protocol to uniquely identify and isolate retinal populations and further study them in vitro. Overall, these studies will serve to further understand the specification of a retinal fate from a pluripotent population. Such information will assist in the establishment of more efficient methods to generate retinal cells from hiPSCs for translational purposes, as well as establish hiPSCs as a unique in vitro model system for studies of the earliest stages of human development. Mentor: Jason S. Meyer1-

Chemical tagging can work: Identification of stellar phase-space structures purely by chemical-abundance similarity

Chemical tagging promises to use detailed abundance measurements to identify spatially separated stars that were in fact born together (in the same molecular cloud), long ago. This idea has not yielded much practical success, presumably because of the noise and incompleteness in chemical-abundance measurements. We have succeeded in substantially improving spectroscopic measurements with The Cannon, which has now delivered 15 individual abundances for ~100,000 stars observed as part of the APOGEE spectroscopic survey, with precisions around 0.04 dex. We test the chemical-tagging hypothesis by looking at clusters in abundance space and confirming that they are clustered in phase space. We identify (by the k-means algorithm) overdensities of stars in the 15-dimensional chemical-abundance space delivered by The Cannon, and plot the associated stars in phase space. We use only abundance-space information (no positional information) to identify stellar groups. We find that clusters in abundance space are indeed clusters in phase space. We recover some known phase-space clusters and find other interesting structures. This is the first-ever project to identify phase-space structures at survey-scale by blind search purely in abundance space; it verifies the precision of the abundance measurements delivered by The Cannon; the prospects for future data sets appear very good.Comment: accepted for publication in the Ap

Complication Rate and Pitfalls of Temporary Bridging External Fixator in Periarticular Communited Fractures

BACKGROUND: A second staged operation using temporary bridging external fixation (TBEF) has been widely used in patients with periarticular complex fracture, yet few papers have been published on the related complications. The purpose of this study was to report the complication rate and pitfalls directly related to TBEF through a retrospective study and to suggest some solutions. METHODS: Fifty-nine cases that were treated by using TBEF were studied among 195 periarticular complex fractures. We retrospectively collected the clinical and radiological data and then the study data was evaluated for 1) cases with unsatisfactory restoration of length, 2) cases with deep infection caused by half pins invading the zone of definitive fixation, and 3) neurovascular injuries related to half pins. RESULTS: Complications were observed in 7/59 cases (11%). Problems related to the achievement of length were observed in one case of distal tibia fracture and 2 cases of distal femur fracture. Half pin related infection was observed in 2 cases of distal femur fracture. Neurovascular injury (medial calcaneal nerve injury in a distal tibia fracture) was observed in 2 cases. Among 7 complications, four were related to using TBEF in distal femur fracture. This is because the abundant leg muscles have strong deforming force and infection might be increased due to frequent irritation by the half pins. CONCLUSIONS: TBEF is a simple procedure with several advantages. However, complications might be observed if certain principles are not followed. It is thought that many complications due to TBEF can be reduced if the half pins are not inserted in the zone of injury, restoration of length is fully achieved and the neurovascular characteristics are carefully considered. In particular, much more caution is needed in the distal femur, which has abundant muscles surrounding it.ope

On the discovery of K-enhanced and possibly Mg-depleted stars throughout the Milky Way

Stars with unusual elemental abundances offer clues about rare astrophysical events or nucleosynthetic pathways. Stars with significantly depleted magnesium and enhanced potassium ([Mg/Fe] 1) have to date only been found in the massive globular cluster NGC 2419 and, to a lesser extent, NGC 2808. The origin of this abundance signature remains unknown, as does the reason for its apparent exclusivity to these two globular clusters. Here we present 112 field stars, identified from 454,180 LAMOST giants, that show significantly enhanced [K/Fe] and possibly depleted [Mg/Fe] abundance ratios. Our sample spans a wide range of metallicities (-1.5 < [Fe/H] < 0.3), yet none show abundance ratios of [K/Fe] or [Mg/Fe] that are as extreme as those observed in NGC 2419. If confirmed, the identified sample of stars represents evidence that the nucleosynthetic process producing the anomalous abundances ratios of [K/Fe] and [Mg/Fe] probably occurs at a wide range of metallicities. This would suggest that pollution scenarios that are limited to early epochs (such as Population III supernovae) are an unlikely explanation, although they cannot be ruled out entirely. This sample is expected to help guide modelling attempts to explain the origin of the Mg-K abundance signature

Automated pupillometry and optic nerve sheath diameter ultrasound to define tuberculous meningitis disease severity and prognosis

Background: Tuberculous meningitis (TBM) causes high mortality and morbidity, in part due to raised intracranial pressure (ICP). Automated pupillometry (NPi) and optic nerve sheath diameter (ONSD) are both low-cost, easy-to-use and non-invasive techniques that correlate with ICP and neurological status. However, it is uncertain how to apply these techniques in the management of TBM. Methods: We conducted a pilot study enrolling 20 adults with TBM in the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. Our objective was to investigate the relationships between baseline and serial measurements of NPi and ONSD and disease severity and outcome. Serial NPi and ONSD were performed for 30 days, at discharge, and at 3-months, with measurements correlated with clinical progression and outcomes. Results: ONSD and NPi measurements had an inverse relationship. Higher ONSD and lower NPi values were associated with lower Glasgow coma score. Baseline NPi was a strong predictor 3-month outcome (median NPi 4.55, interquartile range 4.35–4.65 for good outcomes versus 2.60, IQR 0.65–3.95 for poor outcomes, p = 0.002). Pupil inequality (NPi ≥0.7) was also strongly associated with poor 3-month outcomes (p = 0.006). Individual participants' serial NPi and ONSD were variable during initial treatment and correlated with clinical condition and outcome. Conclusion: Pupillometry and ONSD may be used to predict clinical deterioration and outcome from TBM. Future, larger studies are need explore the optimal timing of measurements and to define how they might be used to optimise treatments and improve outcomes from TBM