Single and combined removal of Cr(VI) and Cd(II) by nanoscale zero-valent iron in the absence and presence of EDDS.

This study examined the feasibility of nanoscale zero-valent iron (nZVI) for the single and combined removal of Cr(VI) and Cd(II) with or without ethylene diamine disuccinic acid (EDDS). The effects of pH and dissolved oxygen (DO) on the removal process were investigated. Results show that the single removal of either Cr(VI) or Cd(II) by nZVI was pH dependent, where the higher Cr(VI) removal was achieved under acidic conditions, whereas the higher Cd(II) removal was achieved under alkaline conditions. The presence of DO enhanced Cd(II) removal but inhibited Cr(VI) removal under alkaline conditions. In the co-existence of Cr(VI) and Cd(II), it was found that Cd(II) exerted insignificant effect on Cr(VI) removal, while the presence of Cr(VI) remarkably enhanced the Cd(II) removal. The addition of EDDS exhibited different influences on Cr(VI) and Cd(II) removal, which were associated with pH and DO. The EDDS enhanced Cr(VI) removal at pH 5.6-9.0 in the absence of DO, but decreased Cr(VI) removal at pH 9.0 in the presence of DO. For the removal of Cd(II) at pH 5.6-7.0, either facilitation or inhibition effect of EDDS was observed, depending on EDDS concentration and the co-existence of Cr(VI). However, Cd(II) removal was always significantly inhibited by EDDS at pH 9.0.

[Establishment of method and modification of colorimetric judgment on HIV-1 virus detection by reverse transcription loop-mediated isothermal amplification].

OBJECTIVE: To establish the reverse transcription loop-mediated isothermal amplification (RT-LAMP) methods for on-site HIV-1 detection. METHODS: As for the real-time fluorescent RT-LAMP, we firstly tested the specificity and sensitivity, then explored its quantitative determination, and finally applied the method to the detection of 35 HIV-1 positive samples. For colorimetric judgment, after choosing different ameliorates to modify Hydroxynaphthol blue (HNB), we tested their real effects on coloration, and then picked out the modified dyes with obvious color change to test the sensitivity and the detection of the 35 HIV-1-positive samples. RESULTS: The real-time fluorescent RT-LAMP showed great specificity of HIV-1, and the sensitivity to detect HIV-1 RNA was between 10 and 100 copies per reaction. On testing 35 HIV-1-positive samples, the method could reach 100 percent detection rate. However, for the quantitative determination, the quantitative relation was not observed regarding the HIV-1 RNA of below 10(3) copies per reaction. Three modified HNB dyes with clear color variation between the reaction tubes of the negative and the positive were got in the study, and their sensitivities equaled to the level of agarose gel electrophoresis. Similarly, 100% (35/35) detection rate was reached when the colorimetric RT-LAMP with the modified dyes was applied to detect 35 HIV-1-positive samples. CONCLUSION: The established real-time fluorescence method and the modified color judgment of RT-LAMP could be helpful for truly achieving rapid, accurate, and sensitive on-site detection of HIV-1.

Application of 68Ga-citrate PET/CT for differentiating periprosthetic joint infection from aseptic loosening after joint replacement surgery.

AIMS: We aimed to evaluate the utility of 68Ga-citrate positron emission tomography (PET)/CT in the differentiation of periprosthetic joint infection (PJI) and aseptic loosening (AL), and compare it with 99mTc-methylene bisphosphonates (99mTc-MDP) bone scan. METHODS: We studied 39 patients with suspected PJI or AL. These patients underwent 68Ga-citrate PET/CT, 99mTc-MDP three-phase bone scan and single-photon emission CT (SPECT)/CT. PET/CT was performed at ten minutes and 60 minutes after injection, respectively. Images were evaluated by three nuclear medicine doctors based on: 1) visual analysis of the three methods based on tracer uptake model, and PET images attenuation-corrected with CT and those not attenuation-corrected with CT were analyzed, respectively; and 2) semi-quantitative analysis of PET/CT: maximum standardized uptake value (SUVmax) of lesions, SUVmax of the lesion/SUVmean of the normal bone, and SUVmax of the lesion/SUVmean of the normal muscle. The final diagnosis was based on the clinical and intraoperative findings, and histopathological and microbiological examinations. RESULTS: Overall, 23 and 16 patients were diagnosed with PJI and AL, respectively. The sensitivity and specificity of three-phase bone scan and SPECT/CT were 100% and 62.5%, 82.6%, and 100%, respectively. Attenuation correction (AC) at 60 minutes and non-AC at 60 minutes of PET/CT had the same highest sensitivity and specificity (91.3% and 100%), and AC at 60 minutes combined with SPECT/CT could improve the diagnostic efficiency (sensitivity = 95.7%). Diagnostic efficacy of the SUVmax was low (area under the curve (AUC) of ten minutes and 60 minutes was 0.814 and 0.806, respectively), and SUVmax of the lesion/SUVmean of the normal bone at 60 minutes was the best semi-quantitative parameter (AUC = 0.969). CONCLUSION: 68Ga-citrate showed the potential to differentiate PJI from AL, and visual analysis based on uptake pattern of tracer was reliable. The visual analysis method of AC at 60 minutes, combined with 99mTc-MDP SPECT/CT, could improve the sensitivity from 91.3% to 95.7%. In addition, a major limitation of our study was that it had a limited sample size, and more detailed studies with a larger sample size are warranted. Cite this article: Bone Joint Res 2022;11(6):398-408.

[Effectiveness comparison of LARS artificial ligament and autogenous hamstring tendon in one-stage reconstruction of anterior and posterior cruciate ligaments].

OBJECTIVE: To compare the effectiveness of arthroscopic one-stage reconstruction of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with LARS artificial ligament and autogenous hamstring tendon, respectively. METHODS: A retrospective study was performed on 23 patients with ACL and PCL injuries, who were treated with one-stage reconstruction, between June 2013 and June 2017. The ACL and PCL were reconstructed with LARS artificial ligament in 11 patients (artificial ligament group) and autogenous hamstring tendon in 12 patients (autogenous tendon group). There was no significant difference in gender, age, side of injury, cause of injury, time from injury to operation, and preoperative Lysholm score and International Knee Documentation Committee (IKDC) score between the two groups ( P>0.05). The operation time, the time of recovery of daily activities and preoperative exercise level, the occurrence of surgical-related complications, Lysholm score, IKDC score, and the results of knee stability assessment were recorded and compared between the two groups. RESULTS: The operation time and the time of recovery of daily activities and preoperative exercise level were significantly shorter in artificial ligament group than in autogenous tendon group ( P<0.05). All incisions healed primarily. In autogenous tendon group, the common fibular nerve injury occurred in 1 case and intermuscular vein thrombosis occurred in 1 case. No complication occurred in the remaining patients of the two groups. All the patients were followed up 24-54 months (mean, 36.4 months). At last follow-up, the Lysholm score and IKDC score of the two groups were significantly higher than preoperative scores ( P<0.05). There was no significant difference between the two groups ( P>0.05). The varus and valgus stress tests of the two groups were negative. There was no significant difference in anterior drawer test, posterior drawer test, and Lachman test between the two groups ( P>0.05). CONCLUSION: The effectiveness of arthroscopic one-stage reconstruction of ACL and PCL with LARS artificial ligament or autogenous hamstring tendon was similar. The knee function and stability recover well. But the patients with LARS artificial ligament reconstruction can resume daily activities and return to exercise earlier.

Chromate removal by surface-modified nanoscale zero-valent iron: Effect of different surface coatings and water chemistry.

This study investigated the correlation between the colloidal stability and reactivity of surface-modified nano zero-valent iron (SM-nZVI) as affected by the surface coating (i.e., polyacrylic acid [PAA] and starch) under various geochemical conditions. Generally, the colloidal stability of nZVI was enhanced with increasing loading of surface coating, while there is an optimum loading for the most efficient Cr(VI) removal by SM-nZVI. At lower loadings than the optimum loading, the surface coating could enhance the particle stabilization, facilitating the Cr(VI) reduction by providing more available surface sites. However, the over-loaded surface coating on the surface of nZVI particles decreased the Cr(VI) reduction due to the occupation of the reactive sites and the inhibition of the mass transfer of Cr(VI) ions from water to the particle surface by providing the electrostatic or steric repulsion. The effects of Ca(2+) ions or humic acid (HA) on the colloidal stability and reactivity of PAA-modified nZVI (P-nZVI) and starch-modified nZVI (S-nZVI) were examined. Differing stability behavior and reactivity were observed for different SM-nZVI. It was found that the presence of Ca(2+) or HA altered surface chemistry of SM-nZVI, the particle-particle interaction and the particle-contaminant interaction, and hence influencing the stability behavior and reactivity of the particles.

The dual effects of carboxymethyl cellulose on the colloidal stability and toxicity of nanoscale zero-valent iron.

Nanoscale zero-valent iron (NZVI) particles are usually modified with surface coating to mitigate the particle stability in water during the environmental application. However, the surface coating may not only influence the particle stabilization but also the particle cytotoxicity. In this study, we investigated the dual effects of carboxymethyl cellulose (CMC) on the colloidal stability and cytotoxicity of NZVI towards gram-negative Escherichia coli (E. coli) and discussed the interrelation between particle stability and cytotoxicity. The effect of CMC concentration, ionic strength (Ca(2+)) and aging treatment on the particle cytotoxicity were also examined. Specifically, the aqueous stability of NZVI suspensions with CMC ratio dose-dependently strengthened within 1 h. The inactivation of E. coli by bare NZVI was significant and concentration- and time-dependent. On the contrary, an increasing reduction in cytotoxicity of NZVI with CMC ratio increasing was observed, even though the particles became more dispersed. TEM analysis demonstrates the membrane disruption and the cellular internalization of nanoparticles after exposure of E. coli to NZVI. However, in the case of CMC-modified NZVI (CNZVI), the bacterial cell wall displays an outer shell of a layer of nanoparticles attached around the outer membrane, but the cell membrane was kept intact. The presence of Ca(2+) can either increase or decrease the cytotoxicity of NZVI and CNZVI, depending on the concentration. The aged NZVI and CNZVI particles did not seem to present obvious bactericidal effect due to the transformation of Fe(0) to the less toxic or non-toxic iron oxides, as indicated by the XRD analysis.

Influence of fulvic acid on the colloidal stability and reactivity of nanoscale zero-valent iron.

This study investigated the effect of fulvic acid (FA) on the colloidal stability and reactivity of nano zero-valent iron (nZVI) at pH 5, 7 and 9. The sedimentation behavior of nZVI differed at different pH. A biphasic model was used to describe the two time-dependent settling processes (i.e., a rapid settling followed by a slower settling) and the settling rates were calculated. Generally, the settling of nZVI was more significant at the point of zero charge (pHpzc), which could be varied in the presence of FA due to the adsorption of FA on the nZVI surface. More FA was adsorbed on the nZVI surface at pH 5-7 than pH 9, resulting in the varying sedimentation behavior of nZVI via influencing the electrostatic repulsion among particles. Moreover, it was found that there was a tradeoff between the stabilization and the reactivity of nZVI as affected by the presence of FA. When FA concentration was at a low level, the adsorption of FA on the nZVI surface could enhance the particle stabilization, and thus facilitating the Cr(VI) reduction by providing more available surface sites. However, when the FA concentrations were too high to occupy the active surface sites of nZVI, the Cr(VI) reduction could be decreased even though the FA enhanced the dispersion of nZVI particles. At pH 9, the FA improved the Cr(VI) reduction by nZVI. Given the adsorption of FA on the nZVI surface was insignificant and its effect on the settling behavior of nZVI particles was minimal, it was proposed that the FA formed soluble complexes with the produced Fe(III)/Cr(III) ions, and thus reducing the degree of passivation on the nZVI surface and facilitating the Cr(VI) reduction.

Aging study on carboxymethyl cellulose-coated zero-valent iron nanoparticles in water: Chemical transformation and structural evolution.

To assess the long-term fate and the associated risks of nanoscale zero-valent iron (nZVI) used in the water remediation, it is essential to understand the chemical transformations during aging of nZVI in water. This study investigated the compositional and structural evolution of bare nZVI and carboxymethyl cellulose (CMC) coated nZVI in static water over a period of 90 days. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the corrosion products of nZVI and CMC-nZVI. Results show that both the structures and the compositions of the corrosion products change with the process of aging, but the coating of CMC could slow down the aging rate of nZVI (as indicated by the slower drop in Fe(0) intensity in XRD pattern). For the bare nZVI, magnetite (Fe3O4) and/or maghemite (γ-Fe2O3) are the dominant corrosion products after 90 days of aging. However, for the CMC-nZVI, the core-shell spheres collapses to acicular-shaped structures after aging with crystalline lepidocrocite (γ-FeOOH) as the primary end product. Moreover, more lepidocrocite present in the corrosion products of CMC-nZVI with higher loading of CMC, which reveals that the CMC coating could influence the transformation of iron oxides.

Rapid quantitative detection of Human immunodeficiency virus type 1 by a reverse transcription-loop-mediated isothermal amplification assay.

Accurate and rapid quantitation of Human immunodeficiency virus type 1 (HIV-1) RNA levels is a critical aspect in estimating the effect of antiviral therapy and establishing therapeutic schedule. Thus, for the first time, a rapid quantitative reverse transcription-loop-mediated isothermal amplification (RT-LAMP) was designed to quantitate HIV-1 RNA. The results showed that the dynamic range was from 2.5×10(2) to 10(7) copies with a coefficient of determination (R(2)) of 0.991, and the limit of detection of RT-LAMP by Probit analysis at the 95% detection level was 196 copies. The intra-assay coefficient of variation (CV) ranged from 0.67% to 2.08% at 10(7) copies and 7.25% to 12.97% at 250 copies. The CVs of inter-assay were 2.39% and 13.93% for the high and low copy numbers, respectively. No cross-reaction with Human immunodeficiency virus type 2 (HIV-2), Human T lymphotrophic virus type 1 (HTLV-1) and Hepatitis C virus (HCV) was observed and a good agreement between the RT-LAMP method and the real-time reverse transcription-polymerase chain reaction (qRT-PCR) test was achieved. This proposed RT-LAMP method could be useful for rapid diagnosis of high risk group and pharmacodynamic assessment of anti-HIV drug, especially in less-equipped laboratories of impoverished areas.

[Visual detection of HIV-1 by reverse transcription loop-mediated isothermal amplification with the hydroxynaphthol blue dye].

OBJECTIVE: A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for rapid visual detection of HIV-1. METHODS: RT-LAMP primers were designed according to conservative sequences of HIV-1 gag gene, and their sensitivity and specificity were evaluated by the established RT-LAMP protocol with the addition of the hydroxynaphthol blue (HNB) dye prior to amplification. The performance of RT-LAMP on clinical samples was compared with real-time reverse transcription PCR(qRT-PCR). RESULTS: The RT-LAMP assay showed a high specificity, and its detection limit was 1000 copies RNA per tube. The sensitivity and specificity of this method using 43 clinical samples were 94.6% and 100%, respectively,in comparison with those of qRT-PCR. CONCLUSION: RT-LAMP assay using hydroxynaphthol blue dye does not need expensive instruments, and offer an alternative for the rapid detection of HIV-1 with the potential to be applied in field diagnosis.

[Colorimetric detection of norovirus genotype GII by reverse transcription loop-mediated isothermal amplification].

A simple, rapid and sensitive colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) method was established to detect norovirus genotype GII. The method employed a set of six specially designed primers that recognized eight distinct sequences of RNA-dependant RNA polymerase and capsid protein gene for amplification of nucleic acid under isothermal conditions at 65 degrees C for 60 minutes. The amplification process of RT-LAMP was monitored by the addition of HNB (Hydroxy naphthol blue) dye prior to amplification. A positive reaction was indicated by a color change from violet to sky blue and confirmed by agarose electrophoresis. The specificity of the RT-LAMP was validated by detecting several different diarrhea viruses including norovirus genotype GII. The sensitivity was determined by serial dilutions of RNA molecules from in vitro transcription of norovirus genotype GII in parallel with conventional RT-PCR detection. The assay was further evaluated with 93 clinical specimens of diarrhea patients. The results showed that the sensitivity of RT-LAMP was 1 000 copies/microL with a high specificity and the relative sensitivity was at the same level as that of conventional RT-PCR. Positive rate of RT-LAMP in analysis of clinical specimens was approximately the same as that of conventional RT-PCR as well. This colorimetric RT-LAMP assay was potential for rapid detection of norovirus genotype GII on spot due to the observation of visual result with high specificity and sensitivity, time-saving and cost benefit.