Performance of the tuberculin skin test and interferon-γ release assay for detection of tuberculosis infection in immunocompromised patients in a BCG-vaccinated population

<p>Abstract</p> <p>Background</p> <p>Interferon-γ release assay (IGRA) may improve diagnostic accuracy for latent tuberculosis infection (LTBI). This study compared the performance of the tuberculin skin test (TST) with that of IGRA for the diagnosis of LTBI in immunocompromised patients in an intermediate TB burden country where BCG vaccination is mandatory.</p> <p>Methods</p> <p>We conducted a retrospective observational study of patients given the TST and an IGRA, the QuantiFERON-TB Gold In-Tube (QFT-IT), at Severance Hospital, a tertiary hospital in South Korea, from December 2006 to May 2009.</p> <p>Results</p> <p>Of 211 patients who underwent TST and QFT-IT testing, 117 (55%) were classified as immunocompromised. Significantly fewer immunocompromised than immunocompetent patients had positive TST results (10.3% vs. 27.7%, p 0.001), whereas the percentage of positive QFT-IT results was comparable for both groups (21.4% vs. 25.5%). However, indeterminate QFT-IT results were more frequent in immunocompromised than immunocompetent patients (21.4% vs. 9.6%, p 0.021). Agreement between the TST and QFT-IT was fair for the immunocompromised group (κ = 0.38), but moderate agreement was observed for the immunocompetent group (κ = 0.57). Indeterminate QFT-IT results were associated with anaemia, lymphocytopenia, hypoproteinemia, and hypoalbuminemia.</p> <p>Conclusion</p> <p>In immunocompromised patients, the QFT-IT may be more sensitive than the TST for detection of LTBI, but it resulted in a considerable proportion of indeterminate results. Therefore, both tests may maximise the efficacy of screening for LTBI in immunocompromised patients.</p

Kinetics and Mechanism of the Sonolytic Destruction of Methyltert-Butyl Ether by Ultrasonic Irradiation in the Presence of Ozone

The kinetics and mechanism of the sonolytic degradation of methyl tert-butyl ether (MTBE) have been investigated at an ultrasonic frequency of 205 kHz and power of 200 W L^(-1). The observed first-order degradation rate constant for the loss of MTBE increased from 4.1 × 10^(-4) s^(-1) to 8.5 × 10^(-4) s^(-1) as the concentration of MTBE decreased from 1.0 to 0.01 mM. In the presence of O_3, the sonolytic rate of destruction of MTBE was accelerated substantially. The rate of MTBE sonolysis with ozone was enhanced by a factor of 1.5−3.9 depending on the initial concentration of MTBE. tert-Butyl formate, tert-butyl alcohol, methyl acetate, and acetone were found to be the primary intermediates and byproducts of the degradation reaction with yields of 8, 5, 3, and 12%, respectively. A reaction mechanism involving three parallel pathways that include the direct pyrolytic decomposition of MTBE, the direct reaction of MTBE with ozone, and the reaction of MTBE with hydroxyl radical is proposed

The Sonolytic Destruction of Methyl tert-Butyl Ether Present in Contaminated Groundwater

Ultrasonic irradiation in the presence of ozone was used to efficiently eliminate methyl tert-butyl ether (MTBE) from groundwater. The sonolytic degradation of MTBE was investigated in three different reactor configurations and frequencies: vibrating-plate reactor (VPR, 358 kHz), near-field acoustical processor (NAP 20 and 16 kHz), and radial-tube resonator (RTR, 20 kHz). The sonochemical reactors can be ordered in terms of their efficiency with respect to the degradation of MTBE in the following way: VPR > RTR > NAP. The higher elimination rates of MTBE in groundwater by combined ultrasound–ozone systems are attributed to the effective conversion of ozone to the OH radical, even in the presence of high alkalinity. Carbonate radicals, which were formed from the oxidation of bicarbonate by hydroxyl radicals, are shown to react with MTBE via a hydrogen-atom abstraction pathway. Methyl-tert-butyl ether was also rapidly eliminated from the groundwater underlying a major international airport by direct chemical oxidation with a mixture of hydrogen peroxide and ozone

Comparing Graphene Oxide and Reduced Graphene Oxide as Blending Materials for Polysulfone and Polyvinylidene Difluoride Membranes

Graphene is a single atomic plane of graphite, and it exhibits unique electronic, thermal, and mechanical properties. Exfoliated graphene oxide (GO) contains various hydrophilic functional groups, such as hydroxyl, epoxide, and carboxyl groups, that can modify the hydrophobic characteristics of a membrane surface. Though reduced graphene oxide (rGO) has fewer functional groups than GO, its associated sp2 structures and physical properties can be recovered. A considerable amount of research has focused on the use of GO to obtain a pristine graphene material via reduction processes. In this study, polysulfone (PSf) and polyvinylidene fluoride (PVDF) membranes that were blended with GO and rGO, respectively, were fabricated by using the immersion phase inversion method and an n-methylpyrrolidone (NMP) solvent. Results showed that the graphene nanomaterials, GO and rGO, can change the pore morphology (size and structure) of both PSf and PVDF membranes. The optimum content of both was then investigated, and the highest flux enhancement was observed with the 0.10 wt% GO-blended PSf membrane. The presence of functional groups in GO within prepared PSf and PVDF membranes alters the membrane characteristics to hydrophilic. An antifouling test and rejection efficiency evaluation also showed that the 0.10 wt% membrane provided the best performance

Sonolytic Destruction of Methyltert-Butyl Ether by Ultrasonic Irradiation: The Role of O_3, H_2O_2, Frequency, and Power Density

The kinetics of degradation of methyl tert-butyl ether (MTBE) by ultrasonic irradiation in the presence of ozone as functions of applied frequencies and applied power are investigated. Experiments are performed over the frequency range of 205−1078 kHz. The higher overall reaction rates are observed at 358 and 618 kHz and then at 205 and 1078 kHz. The observed pseudo-first-order rate constant, k_0, for MTBE degradation increases with increasing power density up to 250 W L^(-1). A linear dependence of the first-order rate constant, k_(O_3), for the simultaneous degradation of O_3 on power density is also observed. Naturally occurring organic matter (NOM) is shown to have a negligible effect on observed reaction rates

Bamboo sawdust-derived high surface area activated carbon for remarkable removal of paracetamol from aqueous solution: sorption kinetics, isotherm, thermodynamics, and regeneration studies

Due to its widespread consumption, paracetamol (PCT) has emerged as one of the leading contaminants that pollute water. Herein, a PCT removal of 99.6% was achieved using chemically activated carbon (CAC), derived from bamboo sawdust using KOH/FeCl3 as an activating agent, at optimal conditions of PCT (20 mg/L), CAC (0.5 g/L), contact time (90 min), and pH (8). Kinetic study revealed that the PCT adsorption process followed the pseudo-second-order kinetic model (R2 = 0.99), indicating that chemical adsorption dominated the adsorption mechanism. On the other hand, isotherm experimental data were best described by the Langmuir (R2 = 0.98) and Freundlich (R2 = 0.96) models. CAC had a maximum Langmuir monolayer capacity of 188.67 mg/g at a PCT concentration of 120 mg/L. Moreover, the Redlich–Peterson model gave the best fit (R2 = 0.99) to the experimental data, confirming that PCT adsorption was monolayer adsorption onto the heterogeneous surface. Thermodynamically, the PCT adsorption was exothermic, spontaneous, and favorable. The reusability study depicted that CAC can be successfully reused for five consecutive adsorption–desorption cycles. Furthermore, the application of CAC to environmental samples showed interesting results. The overall adsorption study indicated that CAC could serve as a promising adsorbent for eliminating PCT from water. HIGHLIGHTS Bamboo sawdust is an abundant waste material.; Highly efficient CAC adsorbent was synthesized from bamboo sawdust.; Bamboo sawdust-derived activated carbon showed remarkable PCT removal from aqueous solution.; Combined activation of bamboo sawdust (FeCl3 + KOH) resulted in superior removal of PCT from aqueous solution.; Application of CAC on real environmental samples indicated promising results.

Enhanced ciprofloxacin removal from aqueous solution using a chemically modified biochar derived from bamboo sawdust: Adsorption process optimization with response surface methodology

Contamination of water by ciprofloxacin has become a significant concern due to its adverse health effects and growing evidence of antimicrobial-resistant genes evolution. To this end, a chemically modified bamboo biochar was prepared from bamboo sawdust to effectively remove ciprofloxacin (CIP) from an aqueous solution. Under similar adsorption conditions, the modified bamboo biochar (MBC) has an excellent CIP removal efficiency (96%) compared to unmodified bamboo biochar (UBC) efficiency (45%). Thus, MBC was used in batch adsorption experiments and the process was optimized with the central composite design (CCD) framework of response surface methodology (RSM). Sorption process parameters such as initial CIP concentration, pH, adsorbent dose, and contact time were studied and found to have a significant effect on CIP removal. The optimal CIP removal (96%) was obtained at MBC dose (0.5 g L-1), CIP initial concentration (20 mg L-1), pH (7.5), and contact time (46 min). The adsorption kinetic data were well described by the pseudo-second-order model (R2 = 0.999), and both Langmuir (R2 = 0.994) and Freundlich (R2 = 0.972) models gave the best fit in CIP adsorption isotherm analysis. The maximum monolayer adsorption capacity of the MBC was 78.43 mg g-1 based on the Langmuir isotherm model. These results suggest that CIP adsorption was mainly controlled by chemisorption. Moreover, the CIP adsorption process was endothermic and spontaneous. Overall, MBC is a low-cost, efficient, and recyclable adsorbent for eliminating emerging contaminants such as ciprofloxacin from an aqueous solution

Characterization of the native oxides of galvanized iron for automobile industry by XPS depth profile with change of ion beam sputtering energy

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