Selenium in surface and irrigation water in the Kendrick irrigation district, Wyoming.

High selenium (Se) concentrations have been found in surface waters in the Kendrick Reclamation Project, Wyoming. Precipitation and irrigation water moving over seleniferous soils are contributing causes, and drought may exacerbate this. This study surveyed Se concentrations and discharges in local surface streams, irrigation drains, and the delivery canal. Sites were sampled monthly and analyzed for Se and total suspended solids (TSS). A completely randomized design with two factors (soil parent material and location, inside or outside irrigation district) was used. Mean Se concentrations were 64 µg L(-1) inside the irrigation district on shale soils, 17 µg L(-1) inside the district off shale soils, 5 µg L(-1) outside the district on shale soils, and 3 µg L(-1) outside the district off shale soils. Correlations between discharge and Se concentrations were generally negative, while correlations between discharge and Se load were generally positive. There was little correlation between load and concentration, and little correlation between TSS and Se. A comparison of Se concentrations in streams and drains showed Se concentrations were significantly higher (p<0.001) in streams during the irrigation season, but not in the off-season (p=0.515). We conclude that higher discharges decrease Se concentration, but increase load. Conversion from flood to sprinkle irrigation may increase Se concentrations by reducing discharge, but decrease Se loads going into the N. Platte River, and will likely alter the timing and magnitude of flows. Both load and concentration should be considered when implementing Se regulations and standards.

Chondroitin sulphate: an effective joint lubricant?

OBJECTIVE: The effect of chondroitin sulphate (CS) treatment on the friction and deformation characteristics of native and glycosaminoglycan (GAG) deficient articular cartilage was investigated. METHODS: Friction tests were conducted at 0.4 MPa load, in Static and Dynamic models, to determine the startup coefficient of friction (COF) and dynamic COF, respectively. Native cartilage: For each cartilage pin and plate couple, the COF was determined under three consecutive tests - (1) baseline COF in PBS (2) COF in CS lubricant and (3) COF again in PBS, after 24h CS treatment. GAG deficient cartilage: For each cartilage pin and plate couple, the baseline COF was determined in PBS initially and again following enzymatic treatment to deplete GAGs. The specimens were then soaked in CS solution for 24h and the COF determined again in PBS. In a similar manner, friction tests were replaced with indentation tests to study the deformation of the tissue. RESULTS: CS at 50mg/ml significantly lowered the startup COF of native cartilage both as a lubricant and a treatment solution. In the dynamic model, where the fluid load support is sustained at a high level, CS failed to have any effect on the COF of native cartilage. GAG depletion raised the friction and deformation levels of cartilage, and subsequent CS treatment failed to lower them to their native levels. CONCLUSION: CS proved to be an effective lubricant for cartilage under mixed-mode lubrication conditions. However, supplemental CS that diffused into the specimens had no influence on the fluid load support of cartilage.

Effect of nominal stress on the long term friction, deformation and wear of native and glycosaminoglycan deficient articular cartilage.

OBJECTIVES: Earlier in vitro studies have shown that the coefficient of friction (COF) of cartilage decreases with increasing load at the lower end of the physiological loading spectrum. At these lower load levels, depletion of glycosaminoglycans (GAGs) from native cartilage has been shown to elevate the COF levels. The current study evaluated the long-term friction, deformation and wear of native and GAG deficient cartilage at a wide range of physiological stress levels in vitro. METHODS: A pin-on-plate machine (sliding velocity: 4 mm/s and stroke length: 4 mm) was used to measure the COF of native and GAG deficient cartilage at applied contact stress levels of 0.5 MPa, 2 MPa, and 3.15 MPa in 7h long friction tests with phosphate buffered saline (PBS) lubrication. The resultant deformation and wear of the cartilage samples due to the friction tests were measured using a height vernier apparatus and lubricant analysis respectively. RESULTS AND CONCLUSIONS: An increase in contact stress from 0.5 MPa to 3.15 MPa resulted in an increase in the COF and wear of native cartilage samples, due to cartilage tissue's inability to rehydrate itself completely and maintain a high fluid load support at the 4 mm stroke length under high contact stress levels. There was no effect of increasing contact stress levels on the COF and wear of GAG deficient cartilage samples due to the very high deformations observed in these samples and the smoothening of their surfaces under the higher loads, leading to the development of conforming surfaces during articulation.

The effect of glycosaminoglycan depletion on the friction and deformation of articular cartilage.

Glycosaminoglycans (GAGs) have been shown to be responsible for the interstitial fluid pressurization of articular cartilage and hence its compressive stiffness and load-bearing properties. Contradictory evidence has been presented in the literature on the effect of depleting GAGs on the friction properties of articular cartilage. The aim of this study was to investigate the effect of depleting GAGs on the friction and deformation characteristics of articular cartilage under different tribological conditions. A pin-on-plate machine was utilized to measure the coefficient of friction of native and chondroitinase ABC (CaseABC)-treated articular cartilage under two different models: static (4 mm/s start-up velocity) and dynamic (4 mm/s sliding velocity; 4 mm stroke length) under a load of 25 N (0.4 MPa contact stress) and with phosphate-buffered saline as the lubricant. Indentation tests were carried out at 1 N and 2 N loads (0.14 MPa and 0.28 MPa contact stress levels) to study the deformation characteristics of both native and GAG-depleted cartilage samples. CaseABC treatment rendered the cartilage tissue soft owing to the loss of compressive stiffness and a sulphated-sugar assay confirmed the loss of GAGs from the cartilage samples. CaseABC treatment significantly increased (by more than 50 per cent) the friction levels in the dynamic model (p < 0.05) at higher loading times owing to the loss of biphasic lubrication. CaseABC treatment had no effect on friction in the static model in which the cartilage surfaces did not have an opportunity to recover fluid because of static loading unlike the cartilage tissue in the dynamic model, in which translation of the cartilage surfaces was involved, ensuring effective biphasic lubrication. Therefore the depletion of GAGs had a smaller effect on the coefficient of friction for the static model. Indentation tests showed that GAG-depleted cartilage samples had a lower elastic modulus and higher permeability than native tissue. These results corroborate the role of GAGs in the compressive and friction properties of articular cartilage and emphasize the need for developing strategies to control GAG loss from diseased articular cartilage tissue.

The influence of the Ebola outbreak on presumptive and active tuberculosis in Bombali District, Sierra Leone.

Setting: Bombali District, rural Sierra Leone. Objective: To compare the number of patients with presumptive tuberculosis (TB), the number of patients registered with TB (including testing for the human immunodeficiency virus [HIV] and initiation on antiretroviral therapy [ART]) and treatment outcomes during the pre-Ebola, Ebola and post-Ebola disease outbreak periods between 2013 and 2016. Design: This was a cross-sectional study and retrospective cohort analysis of treatment outcomes. Results: The mean monthly number of patients with presumptive TB before, during and post-Ebola was respectively 169, 145 and 210. The mean monthly number of registered TB cases was respectively 57, 57 and 96. Smear-positive TB was the most frequent type of TB, at 75%, 66% and 77%. The proportion of TB patients tested for HIV was 82% pre-Ebola, 74% Ebola and 99% post-Ebola. The proportion of HIV-positive patients with TB initiated on ART was respectively 46%, 85% and 100%. Treatment success among TB patients was 71% in the pre-Ebola period and 89% in the Ebola period (P < 0.001). Conclusion: During the Ebola outbreak, there were decreases in the number of presumptive TB patients and in the proportions of patients diagnosed with smear-positive TB and tested for HIV. The initiation of ART in HIV-infected TB patients and treatment outcomes remained acceptable. Pre-emptive actions are needed to maintain adequate control activities in future outbreaks.

Contexte : District de Bombali, Sierra Leone rurale.Objectif : Comparer le nombre de patients présumés tuberculeux (TB), le nombre enregistrés comme TB (incluant le test du virus de l'immunodéficience humaine [VIH] et la mise en route du traitement antirétroviral [TAR]) et les résultats du traitement pendant les périodes avant, pendant et après Ebola, entre 2013 et 2016.Schéma : Une étude transversale et analyse rétrospective de cohorte des résultats du traitement.Résultats : Le nombre moyen mensuel de patients présumés TB a été 169 avant Ebola, 145 pendant Ebola et 210 après Ebola. Le nombre mensuel moyen de cas de TB enregistrés a été 57 avant Ebola, 57 pendant Ebola et 96 après Ebola. La TB à frottis positif a été le type le plus fréquent, avec 75% avant Ebola, 66% pendant Ebola et 77% après Ebola. Les proportions de patients tuberculeux testés pour le VIH ont été 82% avant Ebola, 74% pendant Ebola et 99% après Ebola et pour les patients tuberculeux VIH positifs mis sous TAR, ces proportions ont été 46% avant Ebola, 85% pendant Ebola et 100% après Ebola. Le taux de succès du traitement des patients tuberculeux a été de 71% pendant les périodes avant Ebola et de 89% pendant Ebola (P < 0,001).Conclusion : Pendant la période de l'Ebola, il y a eu une diminution du nombre de patients présumés tuberculeux et dans les proportions de patients ayant eu un diagnostic de TB à frottis positif et un test VIH. La mise en route du TAR chez les patients infectés par le VIH et les résultats du traitement sont restés acceptables. Des actions préventives sont requises afin de maintenir des activités de lutte suffisantes lors de futures flambée épidémiques.

Marco de referencia: El distrito rural de Bombali en Sierra Leona.Objetivo: Comparar el número de pacientes con presunción clínica de tuberculosis (TB), el número de casos registrados de TB (con inclusión de las pruebas diagnósticas del virus de la inmunodeficiencia humana [VIH] y el inicio del tratamiento antirretrovírico [TAR]) y los desenlaces terapéuticos durante el período anterior a la epidemia del Ébola, durante la misma y después de ella del 2013 al 2016.Método: Un estudio transversal con un análisis retrospectivo de cohortes de los desenlaces terapéuticos.Resultados: El promedio mensual de pacientes con presunción clínica de TB fue como sigue: 169 antes de la epidemia del Ébola, 145 durante la epidemia y 210 después de la misma. El promedio mensual de casos registrados de TB fue 57 antes de la epidemia, 57 durante el brote y 96 después de la misma. La TB con baciloscopia positiva fue el tipo de enfermedad más frecuente y su proporción fue 75% antes de la epidemia del Ébola, 66% durante la misma y 77% después de ella. La proporción de pacientes TB que contaban con pruebas diagnósticas del VIH fue como sigue: 82% antes de la epidemia, 74% durante la misma y 99% después de ella y la proporción de pacientes con diagnóstico de TB y positivos frente al VIH que iniciaron el TAR fue 46% antes de la epidemia, 85% durante la misma y 100% después de ella. El éxito del tratamiento antituberculoso fue de 71% en el período anterior al brote de enfermedad del Ébola y de 89% en el período posterior al mismo (P < 0,001).Conclusión: Durante el período de la epidemia de enfermedad del Ébola se observó una disminución del número de casos con presunción clínica de TB, de la proporción de diagnósticos de TB con baciloscopia positiva y de la proporción de pacientes con pruebas diagnósticas del VIH. La iniciación del TAR en los pacientes coinfectados por el VIH y TB y los desenlaces terapéuticos conservaron proporciones aceptables. Se precisan intervenciones anticipativas, con el fin de mantener actividades de control adecuadas durante los brotes epidémicos en el futuro.

Chemistry of trace elements in coalbed methane product water.

Extraction of methane (natural gas) from coal deposits is facilitated by pumping of aquifer water. Coalbed methane (CBM) product water, produced from pumping ground water, is discharged into associated unlined holding ponds. The objective of this study was to examine the chemistry of trace elements in CBM product water at discharge points and in associated holding ponds across the Powder River Basin, Wyoming. Product water samples from discharge points and associated holding ponds were collected from the Cheyenne River (CHR), Belle Fourche River (BFR), and Little Powder River (LPR) watersheds during the summers of 1999 and 2000. Samples were analyzed for pH, Al (aluminum), As (arsenic), B (boron), Ba (barium), Cr (chromium), Cu (copper), F (fluoride), Fe (iron), Mn (manganese), Mo (molybdenum), Se (selenium), and Zn (zinc). Chemistry of trace element concentrations were modeled with the MINTEQA2 geochemical equilibrium model. Results of this study show that pH of product water for three watersheds increased in holding ponds. For example the pH of CBM product water increased from 7.21 to 8.26 for LPR watershed. Among three watersheds, the CBM product water exhibited relatively less change in trace element concentrations in CHR watershed holding ponds. Concentration of dissolved Al, Fe, As, Se, and F in product water increased in BFR watershed holding ponds. For example, concentration of dissolved Fe increased from 113 to 135 microg/L. Boron, Cu, and Zn concentrations of product water did not change in BFR watershed holding ponds. However, concentration of dissolved Ba, Mn, and Cr in product water decreased in BFR watershed holding ponds. For instance, Ba and Cr concentrations decreased from 445 to 386 microg/L and from 43.6 to 25.1 microg/L, respectively. In the LPR watershed, Al, Fe, As, Se, and F concentrations of product water increased substantially in holding ponds. For example, Fe concentration increased from 192 to 312 microg/L. However, concentration of dissolved Ba, Mn, Cr, and Zn decreased in holding ponds. Geochemical modeling calculations suggested that observed increase of Al and Fe concentrations in holding ponds was due to increase in concentration of Al(OH)(4)(-) and Fe(OH)(4)(-) species in water which were responsible for pH increases. Decreases in Ba, Mn, Cr, and Zn concentrations were attributed to the increase in pH, resulting in precipitates of BaSO(4) (barite), MnCO(3) (rhodochrosite), Cr(OH)(2) (chromium hydroxide), and ZnCO(3) (smithsonite) in pond waters, respectively.

Tribological evaluation of hydrogel articulations for joint arthroplasty applications.

Characterizing the wear behavior of hydrogel articulations is problematic and a standardized method has not yet been developed. The aims of this study were to evaluate the wear resistance of hydrogel-on-hydrogel articulations and to assess the suitability of a submerged measurement technique as a practical and non-destructive method in quantifying their wear rates. Five hydrogel bearings were tested for 5 million cycles using a pin-on-disk tester. As the test progressed, the coefficient of friction increased (Spearman's rho=0.76; p<0.001) while the surfaces of the pins were burnished (Spearman's rho=-0.31; p<0.001) and those of the disks got rougher (Spearman's rho=0.19; p<0.01). Environmental scanning electron microscopy analysis showed no evidence of gross wear and revealed similar surface morphology between contacting and non-contacting regions of specimens. These results support the finding of low wear, which were -1.4±8.3 and 6.6±35.3mm(3)/MC based on submerged and wet weights, respectively. Pins displayed higher wear than disks based on submerged weights. This was anticipated since surfaces of pins were constantly under load and cross-shear while only a portion of the disk in contact with the pin was loaded at a given time. Wet weights, on the other hand, indicated higher wear for disks than pins. In addition, submerged weights yielded a lower standard error of the mean in wear rates than wet weights, 3.7 and 14.6mm(3)/MC, respectively. These results indicated that submerged weights were more suitable than wet weights in quantifying wear of hydrogels in spite of unwanted effects of swelling.

Angiolipoma of the stomach as a cause of chronic upper gastrointestinal bleeding.

Angiolipomas are benign vascular fatty neoplasms, usually found in the subcutis of the trunk. Gastric angiolipomas have not been described. We report a gastric angiolipoma causing chronic gastrointestinal bleeding that did not respond to electrocoagulation and required surgical resection. Its classic endoscopic appearance is described. It may be managed endoscopically, utilizing either heater probe or laser photocoagulation and, therefore, should be recognized endoscopically prior to treatment.