Predictors of standardized in-service examination performance and residency outcomes in a graduate periodontics program.

PURPOSE/OBJECTIVES: The objectives of this study were to assess the influence of learner- and education-related factors on standardized in-service examination performance and determine whether in-service examination scores predict residency outcomes. METHODS: American Academy of Periodontology (AAP) In-service Examination (AIE) scores from 10 periodontics residency classes at a single center were recorded and compared against a panel of learner- and education-related variables using multiple linear regression models. Defined residency outcome measures were analyzed against AIE scores using binomial logistic regression. RESULTS: No evaluated learner- or education-related variable was a statistically significant predictor of AIE score in this study sample. Likewise, AIE score was not a statistically significant predictor of any assessed residency outcome. CONCLUSIONS: The AAP has performed a tremendous service to periodontics residents and programs by marshaling the leadership and expertise necessary to offer a professionally constructed assessment instrument. However, in the current study, no relationship could be identified between AIE score and any outcome, including first-attempt board certification. The AAP In-service Committee appears well situated to provide additional leadership focusing on exam implementation, which may enhance AIE value in competency decision making.

Preparation and Characterization of Photoluminescent Graphene Quantum Dots from Watermelon Rind Waste for the Detection of Ferric Ions and Cellular Bio-Imaging Applications.

Graphene quantum dots (GQDs) were synthesized using watermelon rind waste as a photoluminescent (PL) agent for ferric ion (Fe3+) detection and in vitro cellular bio-imaging. A green and simple one-pot hydrothermal technique was employed to prepare the GQDs. Their crystalline structures corresponded to the lattice fringe of graphene, possessing amide, hydroxyl, and carboxyl functional groups. The GQDs exhibited a relatively high quantum yield of approximately 37%. Prominent blue emission under UV excitation and highly selective PL quenching for Fe3+ were observed. Furthermore, Fe3+ could be detected at concentrations as low as 0.28 µM (limit of detection), allowing for high sensitivity toward Fe3+ detection in tap and drinking water samples. In the bio-imaging experiment, the GQDs exhibited a low cytotoxicity for the HeLa cells, and they were clearly illuminated at an excitation wavelength of 405 nm. These results can serve as the basis for developing an environment-friendly, simple, and cost-effective approach of using food waste by converting them into photoluminescent nanomaterials for the detection of metal ions in field water samples and biological cellular studies.

Alkali/zinc-activated fly ash nanocomposites for dye removal and antibacterial applications.

Fly ash (FA), obtained as waste materials from industrial power plants, is generated in large quantities and low recycling. In this study, re-generation of waste FA as cost-effective materials with adsorbent and antibacterial applications was assessed. Alkaline/zinc-activated fly ash nanocomposite (A-FA/Zn) was prepared using one-pot hydrothermal technique. Those nanocomposites are characterized by high surface area and negatively surface charge, which are important influences contributing to an enhancement in adsorption capacity via increase in the number of adsorptive sites and electrostatic interaction between dye molecules-nanocomposites. Additionally, the presence of Zn ions in the prepared nanocomposites represents a key advantage with respect to enhancing antibacterial activity. The feasibility of further enhancing adsorption and antibacterial mechanisms was also examined. It is anticipated that the findings of this study will provide useful information with respect to the development of simple, eco-friendly and low-cost A-FA/Zn with multifunctional applications as organic dye removal and antibacterial purposes.

Characterization of rare earth elements present in coal ash by sequential extraction.

Although it has recently been reported that notable amounts of rare earth elements (REEs) are present in the residual coal ash, little is currently known regarding the association of these elements with the coal ash matrix, thereby limiting the potential for extraction of REEs from coal ash. In this study, we analyzed the binding characteristics of REEs within coal ash via sequential extraction and examined REE recovery during a coal ash recycling process. Major components of coal ash were found to be mineral oxides, mainly composed of Si, Fe, Al, and Ca, and residual carbons. Bottom and fly ashes were found to contain 185.8 mg/kg and 179.2 mg/kg of REEs, respectively. Tessier sequential extraction confirmed that 85 % of REEs are included in the residual fraction of both bottom and fly ashes. Furthermore, BCR sequential extraction revealed that 60-70 % of REEs are contained within the residual fraction, thereby indicating that REEs are strongly bound in both bottom and fly ashes and the use of very strong acids is required for the thorough extraction of REEs from coal ash. Additionally, it was found that 46.3 % of REEs can be recovered from the wastewaters produced during the process of coal ash-derived zeolite synthesis.

Development of biocatalysts immobilized on coal ash-derived Ni-zeolite for facilitating 4-chlorophenol degradation.

A new type of biocatalyst was developed to facilitate the biochemical decomposition of 4-chlorophenol (4-CP) in this study. Oxydoreductases that catalyze the initial steps of 4-CP biodegradation were immobilized on a synthetic inorganic enzyme support. Type-X zeolite, a high-surface area support, was synthesized from coal fly ash, on which nickel ions were plated by impregnation (Ni-zeolite), followed by the effective immobilization (77.5% immobilization yield) of recombinant monooxygenase (CphC-I), dioxygenase (CphA-I), and flavin reductase (Fre) isolated from Pseudarthrobacter chlorophenolicus A6 and Escherichia coli K-12, respectively. The retained catalytic activity of the enzymes immobilized on Ni-zeolite was as high as 64% of the value for the corresponding free enzymes. The Michaelis-Menten kinetic parameters vmax and KM of the immobilized enzymes were determined to be 0.20 mM·min-1 and 0.44 mM, respectively. These results are expected to provide useful information with respect to the development of novel enzymatic treatments for phenolic hydrocarbon contaminants.

Cause of Death in Utah Avalanche Fatalities, 2006-2007 through 2017-2018 Winter Seasons.

INTRODUCTION: Understanding patterns of avalanche fatalities can aid prevention and rescue strategies. In 2007, we published a report reviewing avalanche deaths in Utah between the 1989-1990 and 2005-2006 winter seasons. In the current report, we discuss Utah avalanche fatalities from the 2006-2007 to 2017-2018 seasons. METHODS: Avalanche fatality data were obtained from the Utah Avalanche Center and Utah State Office of the Medical Examiner. Autopsy reports were reviewed to determine demographic information, type of autopsy (external vs internal), injuries, and cause of death. RESULTS: Thirty-two avalanche deaths occurred in Utah during the study period. The mean (±SD) age of victims was 32±13 (8-54) y. Thirty victims (94%) were male and 2 (6%) were female. Seventy-two percent of deaths were from asphyxiation, 19% from trauma alone, and 9% from a combination of asphyxiation and trauma. Snowmobilers accounted for the largest percentage of avalanche fatalities (15 victims; 47%) during the 2007-2018 period. CONCLUSIONS: Asphyxia continues to be the most prevalent killer in avalanche burial. Patterns of ongoing avalanche deaths continue to suggest that rapid recovery and techniques that prolong survival while buried may decrease fatality rates. Trauma is a significant factor in many avalanche fatalities. Education and technologies focused on reducing traumatic injuries such as improved education in techniques for avalanche risk avoidance and/or use of avalanche airbags may further decrease fatality rates. Snowmobilers represent an increasing percentage of Utah avalanche deaths and now make up the majority of victims; increased education targeting this demographic in the basics of avalanche rescue gear and avalanche rescue may also reduce fatalities.

Evaluation of aromatic hydrocarbon decomposition catalyzed by the dioxygenase system and substitution of ferredoxin and ferredoxin reductase.

In this study, the catalytic activity and kinetic characteristics of the aromatic hydrocarbon dioxygenase system and the possibility of substituting its ferredoxin and ferredoxin reductase components were evaluated. The genes encoding toluene dioxygenase and toluene dihydrodiol dehydrogenase were cloned from Pseudomonas putida F1, and the corresponding enzymes were overexpressed and purified to homogeneity. Oxidative hydroxylation of toluene to cis-toluene dihydrodiol was catalyzed by toluene dioxygenase, and its subsequent dehydrogenation to 3-methylcatechol was catalyzed by toluene dihydrodiol dehydrogenase. The specific activity of the dioxygenase was 2.82 U/mg-protein, which is highly remarkable compared with the values obtained in previous researches conducted with crude extracts or insoluble forms of enzymes. Kinetic parameters, as characterized by the Hill equation, were vmax = 497.2 µM/min, KM = 542.4 µM, and nH = 2.2, suggesting that toluene dioxygenase has at least three cooperative binding sites for toluene. In addition, the use of alternative ferredoxins and reductases was examined. Ferredoxin cloned from CYP153 could transfer electrons to the iron sulfur protein component of toluene dioxygenase. The ferredoxin could be reduced by ferredoxin, rubredoxin, and putidaredoxin reductases of CYP153, alkane-1 monooxygenase, and camphor 5-monooxygenase, respectively. The results provide useful information regarding the effective enzymatic biotreatment of hazardous aromatic hydrocarbon contaminants.

MET in gastric cancer with liver metastasis: The relationship between MET amplification and Met overexpression in primary stomach tumors and liver metastasis.

BACKGROUND AND OBJECTIVES: Although MET amplification/overexpression was observed in a subset of gastric cancer (GC) patients, the relationship between MET amplification/overexpression in primary GC and liver metastasis was unclear. METHODS: GC samples and matched liver metastases (N = 47) were analyzed by fluorescence/silver in-situ hybridization (FISH/SISH) and by immunohistochemistry for MET amplification and MET expression, respectively. MET-copy number (CN) and Met expression data from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD, N = 356) were also analyzed. RESULTS: Significant overlap existed between MET amplification and Met expression in both primary stomach tumors (P = 0.013) and liver metastasis (P = 0.001). In TCGA-STAD, MET-CN (≥4 copies) and MET expression were also positively correlated (r = 0.761; P = 0.017). Comparative analysis revealed a strong association between MET expression and MET amplification (85% concurrence) in primary stomach tumors and matched liver metastasis. MET status in synchronous liver metastasis (N = 36) was correlated with primary stomach tumors. However, a significant correlation between primary tumors and liver metastases was not observed in patients with metachronous liver metastasis. Survival analyses revealed that both MET amplification and MET overexpression were prognostic of poor outcomes. CONCLUSIONS: MET amplification and Met overexpression were positively correlated in GC. MET status should be re-evaluated in GC patients with liver metastasis, especially for metachronous metastasis.

4-Chlorophenol biodegradation facilitator composed of recombinant multi-biocatalysts immobilized onto montmorillonite.

A biodegradation facilitator which catalyzes the initial steps of 4-chlorophenol (4-CP) oxidation was prepared by immobilizing multiple enzymes (monooxygenase, CphC-I and dioxygenase, CphA-I) onto a natural inorganic support. The enzymes were obtained via overexpression and purification after cloning the corresponding genes (cphC-I and cphA-I) from Arthrobacter chlorophenolicus A6. Then, the recombinant CphC-I was immobilized onto fulvic acid-activated montmorillonite. The immobilization yield was 60%, and the high enzyme activity (82.6%) was retained after immobilization. Kinetic analysis indicated that the Michaelis-Menten model parameters for the immobilized CphC-I were similar to those for the free enzyme. The enzyme stability was markedly enhanced after immobilization. The immobilized enzyme exhibited a high level of activity even after repetitive use (84.7%) and powdering (65.8%). 4-CP was sequentially oxidized by a multiple enzyme complex, comprising the immobilized CphC-I and CphA-I, via the hydroquinone pathway: oxidative transformation of 4-CP to hydroxyquinol followed by ring fission of hydroxyquinol.

Synchronous triple occurrence of MALT lymphoma, schwannoma, and adenocarcinoma of the stomach.

We present a case of a 56-year-old man with 3 synchronous gastric tumors. The patient presented with melena, and 3 gastric abnormalities were detected on gastroduodenoscopic examination, including a small ulcerative lesion in the gastric antrum, a submucosal mass in the gastric body, and severe erosion in the fundus. Histological examination of biopsy samples yielded respective diagnoses of gastric adenocarcinoma, gastritis, and mucosa-associated lymphoid tissue (MALT) lymphoma. The patient first received medication to eradicate any underlying Helicobacter pylori infection, which might have been a cause of the MALT lymphoma. Four weeks later, after examination of repeat biopsy samples revealed that the MALT lymphoma had resolved, the patient underwent subtotal gastrectomy. Further histological examination of resected tissue confirmed the antrum lesion as adenocarcinoma and the body lesion as schwannoma. To our knowledge, this is the first reported case of synchronous triple primary gastric adenocarcinoma, MALT lymphoma, and schwannoma.

Identification of the upstream 4-chlorophenol biodegradation pathway using a recombinant monooxygenase from Arthrobacter chlorophenolicus A6.

This study aimed to clarify the initial 4-chlorophenol (4-CP) biodegradation pathway promoted by a two-component flavin-diffusible monooxygenase (TC-FDM) consisting of CphC-I and CphB contained in Arthrobacter chlorophenolicus A6 and the decomposition function of CphC-I. The TC-FDM genes were cloned from A. chlorophenolicus A6, and the corresponding enzymes were overexpressed. Since CphB was expressed in an insoluble form, Fre, a flavin reductase obtained from Escherichia coli, was used. These enzymes were purified using Ni2+-NTA resin. It was confirmed that TC-FDM catalyzes the oxidation of 4-CP and the sequential conversion of 4-CP to benzoquinone (BQN)→hydroquinone (HQN)→HQL. This indicated that CphC-I exhibits substrate specificity for 4-CP, BQN, and HQN. The activity of CphC-I for 4-CP was 63.22U/mg-protein, and the Michaelis-Menten kinetic parameters were vmax=0.21mM/min, KM=0.19mM, and kcat/KM=0.04mM-1min-1. These results would be useful for the development of a novel biochemical treatment technology for 4-CP and phenolic hydrocarbons.

Oxidative biodegradation of 4-chlorophenol by using recombinant monooxygenase cloned and overexpressed from Arthrobacter chlorophenolicus A6.

In this study, cphC-I and cphB, encoding a putative two-component flavin-diffusible monooxygenase (TC-FDM) complex, were cloned from Arthrobacter chlorophenolicus A6. The corresponding enzymes were overexpressed to assess the feasibility of their utilization for the oxidative decomposition of 4-chlorophenol (4-CP). Soluble CphC-I was produced at a high level (∼50%), and subsequently purified. Since CphB was expressed in an insoluble form, a flavin reductase, Fre, cloned from Escherichia coli was used as an alternative reductase. CphC-I utilized cofactor FADH2, which was reduced by Fre for the hydroxylation of 4-CP. This recombinant enzyme complex exhibited a higher specific activity for the oxidation of 4-CP (45.34U/mg-protein) than that exhibited by CphC-I contained in cells (0.18U/mg-protein). The Michaelis-Menten kinetic parameters were determined as: vmax=223.3µM·min-1, KM=249.4µM, and kcat/KM=0.052min-1·µM-1. These results could be useful for the development of a new biochemical remediation technique based on enzymatic agents catalyzing the degradation of phenolic contaminants.

Enzymatic degradation of aromatic hydrocarbon intermediates using a recombinant dioxygenase immobilized onto surfactant-activated carbon nanotube.

This study examined the enzymatic decomposition of aromatic hydrocarbon intermediates (catechol, 4-chlorocatechol, and 3-methylcatechol) using a dioxygenase immobilized onto single-walled carbon nanotube (SWCNT). The surfaces of SWCNTs were activated with surfactants. The dioxygenase was obtained by recombinant technique: the corresponding gene was cloned from Arthrobacter chlorophenolicus A6, and the enzyme was overexpressed and purified subsequently. The enzyme immobilization yield was 62%, and the high level of enzyme activity was preserved (60-79%) after enzyme immobilization. Kinetic analyses showed that the substrate utilization rates and the catalytic efficiencies of the immobilized enzyme for all substrates (target aromatic hydrocarbon intermediates) tested were similar to those of the free enzyme, indicating that the loss of enzyme activity was minimal during enzyme immobilization. The immobilized enzyme was more stable than the free enzyme against abrupt changes in pH, temperature, and ionic strength. Moreover, it retained high enzyme activity even after repetitive use.

Production of electrically-conductive nanoscale filaments by sulfate-reducing bacteria in the microbial fuel cell.

This study reports that the obligate anaerobic microorganism, Desulfovibrio desulfuricans, a predominant sulfate-reducing bacterium (SRB) in soils and sediments, can produce nanoscale bacterial appendages for extracellular electron transfer. These nanofilaments were electrically-conductive (5.81S·m(-1)) and allowed SRBs to directly colonize the surface of insoluble or solid electron acceptors. Thus, the direct extracellular electron transfer to the insoluble electrode in the microbial fuel cell (MFC) was possible without inorganic electron-shuttling mediators. The production of nanofilaments was stimulated when only insoluble electron acceptors were available for cellular respiration. These results suggest that when availability of a soluble electron acceptor for SRBs (SO4(2-)) is limited, D. desulfuricans initiates the production of conductive nanofilaments as an alternative strategy to transfer electrons to insoluble electron acceptors. The findings of this study contribute to understanding of the role of SRBs in the biotransformation of various substances in soils and sediments and in the MFC.

Noncovalent and covalent immobilization of oxygenase on single-walled carbon nanotube for enzymatic decomposition of aromatic hydrocarbon intermediates.

The decomposition of various aromatic hydrocarbon intermediates was examined using a recombinant oxidative enzyme immobilized on single-walled carbon nanotubes (SWCNTs). Hydroxyquinol 1,2-dioxygenase (CphA-I), which catalyzes ring cleavage of catechol and its analogues, was obtained from Arthrobacter chlorophenolicus A6 via cloning, overexpression, and subsequent purification. This recombinant enzyme was immobilized on SWCNTs by physical adsorption and covalent coupling in the absence and presence of N-hydroxysuccinimide. The immobilization yield was as high as 52.1%, and a high level of enzyme activity of up to 64.7% was preserved after immobilization. Kinetic analysis showed that the substrate utilization rates (vmax) and catalytic efficiencies (kcat/KM) of the immobilized enzyme for all substrates evaluated were similar to those of the free enzyme, indicating minimal loss of enzyme activity during immobilization. The immobilized enzyme was more stable toward extreme pH, temperature, and ionic strength conditions than the free enzyme. Thus, the oxidative enzyme immobilized on SWCNTs can be used as an effective and stable biocatalyst for the biochemical remediation process if further investigations would be carried out under field conditions.

Evaluation of soil flushing of complex contaminated soil: an experimental and modeling simulation study.

The removal of heavy metals (Zn and Pb) and heavy petroleum oils (HPOs) from a soil with complex contamination was examined by soil flushing. Desorption and transport behaviors of the complex contaminants were assessed by batch and continuous flow reactor experiments and through modeling simulations. Flushing a one-dimensional flow column packed with complex contaminated soil sequentially with citric acid then a surfactant resulted in the removal of 85.6% of Zn, 62% of Pb, and 31.6% of HPO. The desorption distribution coefficients, KUbatch and KLbatch, converged to constant values as Ce increased. An equilibrium model (ADR) and nonequilibrium models (TSNE and TRNE) were used to predict the desorption and transport of complex contaminants. The nonequilibrium models demonstrated better fits with the experimental values obtained from the column test than the equilibrium model. The ranges of KUbatch and KLbatch were very close to those of KUfit and KLfit determined from model simulations. The parameters (R, ß, ω, α, and f) determined from model simulations were useful for characterizing the transport of contaminants within the soil matrix. The results of this study provide useful information for the operational parameters of the flushing process for soils with complex contamination.

Triple-layered polyurethane prosthesis with wrinkles for repairing partial tracheal defects.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to develop a triple-layered artificial polyurethane (PU) scaffold with a wrinkled layer for reconstruction of partial tracheal defects. STUDY DESIGN: Animal experiment. METHODS: PU/Pluronic F127 solution was transformed into an asymmetrically porous PU membrane by an immersion precipitation method. The nonporous wrinkled film was prepared by a simple casting of the PU solution on a grooved mold. The triple-layered wrinkled PU scaffolds were fabricated by simple inosculating between the wrinkled film and the porous membranes as in a sandwich (porous/wrinkled/porous structure). Scaffolds were transplanted into 10 New Zealand rabbits after creating tracheal windows. Endoscopic and histological examinations and mechanical tests were performed. RESULTS: The thickness and outer pore size of the prepared triple-layered PU scaffold were ∼1.95 mm and ∼200 µm, respectively. The wrinkled PU scaffold showed better maximum flexural strength compared to the nonwrinkled scaffold (1.03 ± 0.19 vs. 0.56 ± 0.09 MPa). Eight of 10 rabbits survived through all of the examinations and procedures. Endoscopic findings revealed that respiratory mucosa was observed over the scaffold at 3 weeks, and it was an entirely covered scaffold at 6 weeks. The circular framework of the tracheal lumen was maintained in seven of 10 rabbits. Histologic findings showed that ciliated respiratory mucosa covered the surface of the scaffolds. The tensile strength of the scaffold-implanted trachea was lower than that of the normal control. CONCLUSIONS: A wrinkled, triple-layered PU scaffold can be used as a ready-made scaffold for reconstruction of partial tracheal defects. LEVEL OF EVIDENCE: NA.

Enhanced current production by Desulfovibrio desulfuricans biofilm in a mediator-less microbial fuel cell.

In this study, a mediator-less microbial fuel cell (MFC) inoculated with a sulfate-reducing bacterium (SBR), Desulfovibrio desulfuricans, was equipped with bare and surface-treated graphite felt electrodes. Electrochemical treatment of the anode surface facilitated biofilm formation on the electrode, resulting in rapid and enhanced current production. The maximum current density of the treated anode was 233±24.2mA/m(2), which was 41% higher than that of the untreated anode. The electron transfer rate also increased from 2.45±0.04 to 3.0±0.02µmol of electrons/mg of protein·min. Biofilm formation on the treated anode was mainly due to the strong hydrogen or peptide bonds between the amide groups of bacterial materials (including cytochrome c) and carboxyl groups formed on the electrodes. These results provide useful information on direct electron transfer by SRB in a mediator-less MFC through cytochrome c and the effects of the electrochemical treatment of electrodes on MFC performance.

pH-rate profiles of L-arabinitol 4-dehydrogenase from Hypocrea jecorina and its application in L-xylulose production.

l-Arabinitol 4-dehydrogenase (LAD) from Hypocrea jecorina (HjLAD) was cloned and overexpressed in Escherichia coli BL21 (DE3). The kinetics of l-arabinitol oxidation by NAD(+), catalyzed by HjLAD, was studied within the pH range of 7.0-9.5 at 25°C. The turnover number (kcat) and the catalytic efficiency (kcat/Km) were 4200min(-1) and 290mM(-1)min(-1), respectively. HjLAD showed the highest turnover number and catalytic efficiency among all previously characterized LADs. In further application of HjLAD, rare l-sugar l-xylulose was produced by the enzymatic oxidation of arabinitol to give a yield of approximately 86%.

Enhanced binding of hydrophobic organic contaminants by microwave-assisted humification of soil organic matter.

Enhanced binding of hydrophobic organic contaminants (HOCs) with soil organic matter (SOM) by microwave (MW) irradiation was investigated in this study. We used fluorescence excitation emission matrix, humification index (HIX), and organic carbon partitioning coefficient (Koc) to examine characteristic changes in SOM and its sorptive capacity for HOCs. When MW was irradiated to soils, protein-like fluorescence decreased but fulvic- and humic-like fluorescence increased. The addition of activated carbon in the presence of oxygen facilitated the humification-like alteration of SOM more significantly, evidenced by increases in fulvic- and humic-like fluorescence signals. The extent of SOM-phenanthrene binding also increased with MW treatment, supported by a notable increase in Koc value from 1.8×10(4) to 7.3×10(5)Lkg(-1). Various descriptors indicating the physical and chemical properties of SOM along with the relative percentage of humic-like fluorescence and HIX values demonstrated strong linear relationships with Koc values. These linear relationships indicated that the increased binding affinity of SOM for phenanthrene was attributed to enhanced SOM humification, which was stimulated by MW irradiation. Thus, our results demonstrate that MW irradiation could be effectively used for remediation or for assessing the environmental risks of HOC-contaminated soils and groundwater.