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1.
Effect of fungal co-cultures on ligninolytic enzyme activities, H2O2 production, and orange G discoloration.
Lira-Pérez, J, Rodríguez-Vázquez, R, Chan-Cupul, W
Preparative biochemistry & biotechnology. 2020;(6):607-618
Abstract
In this study, the effects of Aspergillus niger in coculture with the basidiomycetes, Trametes versicolor, T. maxima, and Ganoderma spp., were studied to assess H2O2 production and laccase (Lac), Lignin Peroxidase (LiP), and manganese peroxidase (MnP) activities. The results indicated that maximum discoloration was of 97%, in the T. maxima and A. niger coculture, where the concentration of H2O2 was 5 mg/L and 6.3 mg/L in cultures without and with dye, respectively. These concentrations of H2O2 were 1.6- and 1.8-fold higher than monocultures of T. maxima (3.37 mg/L) and A. niger (3.87 mg/L), respectively. In the same coculture, the LiP and MnP enzyme activities also increased 12-fold, (from 0.08 U/mg to 0.99 U/mg), and 67-fold, (from 0.11 U/mg to 7.4 U/mg), respectively. The Lac activity increased 1.7-fold (from 13.46 U/mg to 24 U/mg). Further, a Box-Behnken experimental design indicated a 1.8-fold increase of MnP activity (from 7.4 U/mg to 13.3 U/mg). In addition, dye discoloration regression model obtained from the Box-Behnken experimental design showed a positively correlation with H2O2, (R2 = 0.58) and a negatively correlation with Lac activity (R2 = -0.7).
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Hydrogen peroxide and viral infections: A literature review with research hypothesis definition in relation to the current covid-19 pandemic.
Caruso, AA, Del Prete, A, Lazzarino, AI
Medical hypotheses. 2020;:109910
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Abstract
We reviewed the literature concerning the innate response from nasal and oral epithelial cells and their reaction to hydrogen peroxide (H2O2). Hydrogen peroxide is produced physiologically by oral bacteria and plays a significant role in the balance of oral microecology since it is an important antimicrobial agent. In the epithelial cells, the enzyme superoxide dismutase catalyzes a reaction leading from hydrogen peroxide to the ion superoxide. The induced oxidative stress stimulates a local innate response via activation of the toll-like receptors and the NF-κB. Those kinds of reactions are also activated by viral infections. Virus-induced oxidative stress plays an important role in the regulation of the host immune system and the specific oxidant-sensitive pathway is one of the effective strategies against viral infections. Therefore, nose/mouth/throat washing with hydrogen peroxide may enhance those local innate responses to viral infections and help protect against the current coronavirus pandemic. We strongly encourage the rapid development of randomized controlled trials in both SARS-CoV-2 positive and negative subjects to test the preliminary findings from the in-vitro and in-vivo observational studies that we identified.
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3.
In vitro bleaching effect of hydrogen peroxide with different time of exposition and concentration on shear bond strength of orthodontic brackets to human enamel: A meta-analysis of in vitro studies.
Imani, MM, Azizi, F, Bahrami, K, Golshah, A, Safari-Faramani, R
International orthodontics. 2020;(1):22-31
Abstract
INTRODUCTION Controversy exists regarding the effect of bleaching on shear bond strength (SBS) of orthodontic brackets to enamel. This study aims to do a review and meta-analysis on the effect of bleaching with hydrogen peroxide on SBS according to the interval between bleaching and bonding to human enamel and the concentration of Hydrogen Peroxide. METHODS An electronic search of the literature was performed in Scopus, PubMed and Cochrane databases including CENTRAL and Cochrane library for relevant in vitro studies on the effect of bleaching with hydrogen peroxide on shear bond strength of human enamel, published until June 2018. Modified Cochrane Risk of Bias tool was used to assess the quality of the individual studies. AMSTAR tool was used for assessing the quality of the study. RESULTS Nineteen studies were included in the qualitative analysis. Regardless of the interval between bleaching and bonding, reduction in SBS was not statistically significant when the hydrogen peroxide of less than 35% is used. Bleaching with 35% hydrogen reduces SBS when the bonding is conducted immediately (P<0.0001) or the time interval was shorter than one day (P<0.0005). On the other hand, use of high dose hydrogen peroxide resulted in a statistically significant reduction in SBS irrespective of the time interval between the procedures (P<0.05 for all categories of time interval). CONCLUSION Bleaching with hydrogen peroxide decreases the SBS of brackets in patients undergoing orthodontic treatment especially if the time interval between bleaching and bonding procedures is short and a high concentration of hydrogen peroxide is used.
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Oxygen Embolism and Pneumocephalus After Hydrogen Peroxide Application During Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery: A Case Report and Literature Review.
Zou, P, Yang, JS, Wang, XF, Wei, JM, Guo, H, Zhang, B, Zhang, F, Chu, L, Hao, DJ, Zhao, YT
World neurosurgery. 2020;:201-204
Abstract
BACKGROUND Hydrogen peroxide (H2O2) solution is commonly used to irrigate wounds because of its hemostatic and antiseptic properties. Previous studies suggest that H2O2 can result in toxicity to keratinocytes and fibroblasts, but complications after H2O2 application, including oxygen embolism, which is one of the most severe, have rarely been reported. CASE DESCRIPTION A 40-year-old woman was diagnosed with L4-5 lumbar spinal stenosis and subsequently underwent minimally invasive transforaminal lumbar interbody fusion treatment at another hospital. Hypotension, hypoxia, and a decrease in end-tidal carbon dioxide pressure occurred immediately after H2O2 irrigation. After the operation, she was able to be extubated but remained comatose. Postoperative computed tomography scan revealed intracranial air trapping in the right frontal lobe and multiple cerebral infarction foci. CONCLUSIONS When using a knee-prone surgical position or in cases of dural laceration, the application of undiluted H2O2 solution should be avoided, especially in a surgical wound within a closed cavity. When hypotension, hypoxia, and a decrease in end-tidal carbon dioxide pressure occur immediately after H2O2 irrigation, oxygen embolism should be strongly suspected.
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Actin filaments mediated root growth inhibition by changing their distribution under UV-B and hydrogen peroxide exposure in Arabidopsis.
Du, M, Wang, Y, Chen, H, Han, R
Biological research. 2020;(1):54
Abstract
BACKGROUND UV-B signaling in plants is mediated by UVR8, which interacts with transcriptional factors to induce root morphogenesis. However, research on the downstream molecules of UVR8 signaling in roots is still scarce. As a wide range of functional cytoskeletons, how actin filaments respond to UV-B-induced root morphogenesis has not been reported. The aim of this study was to investigate the effect of actin filaments on root morphogenesis under UV-B and hydrogen peroxide exposure in Arabidopsis. RESULTS A Lifeact-Venus fusion protein was used to stain actin filaments in Arabidopsis. The results showed that UV-B inhibited hypocotyl and root elongation and caused an increase in H2O2 content only in the root but not in the hypocotyl. Additionally, the actin filaments in hypocotyls diffused under UV-B exposure but were gathered in a bundle under the control conditions in either Lifeact-Venus or uvr8 plants. Exogenous H2O2 inhibited root elongation in a dose-dependent manner. The actin filaments changed their distribution from filamentous to punctate in the root tips and mature regions at a lower concentration of H2O2 but aggregated into thick bundles with an abnormal orientation at H2O2 concentrations up to 2 mM. In the root elongation zone, the actin filament arrangement changed from lateral to longitudinal after exposure to H2O2. Actin filaments in the root tip and elongation zone were depolymerized into puncta under UV-B exposure, which showed the same tendency as the low-concentration treatments. The actin filaments were hardly filamentous in the maturation zone. The dynamics of actin filaments in the uvr8 group under UV-B exposure were close to those of the control group. CONCLUSIONS The results indicate that UV-B inhibited Arabidopsis hypocotyl elongation by reorganizing actin filaments from bundles to a loose arrangement, which was not related to H2O2. UV-B disrupted the dynamics of actin filaments by changing the H2O2 level in Arabidopsis roots. All these results provide an experimental basis for investigating the interaction of UV-B signaling with the cytoskeleton.
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A quadruple blind, randomised controlled trial of gargling agents in reducing intraoral viral load among hospitalised COVID-19 patients: A structured summary of a study protocol for a randomised controlled trial.
Khan, FR, Kazmi, SMR, Iqbal, NT, Iqbal, J, Ali, ST, Abbas, SA
Trials. 2020;(1):785
Abstract
OBJECTIVES 1- To compare the effectiveness of 1% Hydrogen peroxide, 0.2% Povidone-Iodine, 2% hypertonic saline and a novel solution Neem extract (Azardirachta indica) in reducing intra-oral viral load in COVID-19 positive patients. 2- To determine the salivary cytokine profiles of IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL- 17 among COVID-19 patients subjected to 1% Hydrogen peroxide, 0.2% Povidone-Iodine, 2% hypertonic saline or Neem extract (Azardirachta indica) based gargles. TRIAL DESIGN This will be a parallel group, quadruple blind-randomised controlled pilot trial with an add on laboratory based study. PARTICIPANTS A non-probability, purposive sampling technique will be followed to identify participants for this study. The clinical trial will be carried out at the Aga Khan University Hospital (AKUH), Karachi, Pakistan. The viral PCR tests will be done at main AKUH clinical laboratories whereas the immunological tests (cytokine analysis) will be done at the Juma research laboratory of AKUH. The inclusion criteria are laboratory-confirmed COVID-19 positive patients, male or female, in the age range of 18-65 years, with mild to moderate disease, already admitted to the AKUH. Subjects with low Glasgow coma score, with a history of radiotherapy or chemotherapy, who are more than 7 days past the onset of COVID- 19 symptoms, or intubated or edentulous patients will be excluded. Patients who are being treated with any form of oral or parenteral antiviral therapy will be excluded, as well as patients with known pre-existing chronic mucosal lesions such as lichen planus. INTERVENTION AND COMPARATOR Group A (n=10) patients on 10 ml gargle and nasal lavage using 0.2% Povidone-Iodine (Betadiene® by Aviro Health Inc./ Pyodine® by Brooks Pharma Inc.) for 20-30 seconds, thrice daily for 6 days. Group B (n=10) patients will be subjected to 10 ml gargle and nasal lavage using 1% Hydrogen peroxide (HP® by Karachi Chemicals Products Inc./ ActiveOxy® by Boumatic Inc.) for 20-30 seconds, thrice daily for 6 days. Group C will comprised of (n=10) subjects on 10ml gargle and nasal lavage using Neem extract solution (Azardirachta indica) formulated by Karachi University (chemistry department laboratories) for 20-30 seconds, thrice daily for 6 days. Group D (n=10) patients will use 2% hypertonic saline (Plabottle® by Otsuka Inc.) gargle and nasal lavage for a similar time period. Group E (n=10) will serve as positive controls. These will be given simple distilled water gargles and nasal lavage for 20-30 seconds, thrice daily for six days. For nasal lavage, a special douche syringe will be provided to each participant. Its use will be thoroughly explained by the data collection officer. After each use, the patient is asked not to eat, drink, or rinse their mouth for the next 30 minutes. MAIN OUTCOMES The primary outcome is the reduction in the intra-oral viral load confirmed with real time quantitative PCR. RANDOMISATION The assignment to the study group/ allocation will be done using the sealed envelope method under the supervision of Clinical Trial Unit (CTU) of Aga Khan University, Karachi, Pakistan. The patients will be randomised to their respective study group (1:1:1:1:1 allocation ratio) immediately after the eligibility assessment and consent administration is done. BLINDING (MASKING): The study will be quadruple-blinded. Patients, intervention provider, outcome assessor and the data collection officer will be blinded. The groups will be labelled as A, B, C, D or E. The codes of the intervention will be kept in lock & key at the CTU and will only be revealed at the end of study or if the study is terminated prematurely. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): As there is no prior work on this research question, so no assumptions for the sample size calculation could be made. The present study will serve as a pilot trial. We intend to study 50 patients in five study groups with 10 patients in each study group. For details, please refer to Fig. 1 for details. TRIAL STATUS Protocol version is 7.0, approved by the department and institutional ethics committees and clinical trial unit of the university hospital. Recruitment is planned to start as soon as the funding is sanctioned. The total duration of the study is expected to be 6 months i.e. August 2020-January 2021. TRIAL REGISTRATION This study protocol was registered at www.clinicaltrials.gov on 10 April 2020 NCT04341688 . FULL PROTOCOL The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2). Fig. 1 Flow diagram of study-participants' timeline.
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Progress of Advanced Nanomaterials in the Non-Enzymatic Electrochemical Sensing of Glucose and H2O2.
Thatikayala, D, Ponnamma, D, Sadasivuni, KK, Cabibihan, JJ, Al-Ali, AK, Malik, RA, Min, B
Biosensors. 2020;(11)
Abstract
Non-enzymatic sensing has been in the research limelight, and most sensors based on nanomaterials are designed to detect single analytes. The simultaneous detection of analytes that together exist in biological organisms necessitates the development of effective and efficient non-enzymatic electrodes in sensing. In this regard, the development of sensing elements for detecting glucose and hydrogen peroxide (H2O2) is significant. Non-enzymatic sensing is more economical and has a longer lifetime than enzymatic electrochemical sensing, but it has several drawbacks, such as high working potential, slow electrode kinetics, poisoning from intermediate species and weak sensing parameters. We comprehensively review the recent developments in non-enzymatic glucose and H2O2 (NEGH) sensing by focusing mainly on the sensing performance, electro catalytic mechanism, morphology and design of electrode materials. Various types of nanomaterials with metal/metal oxides and hybrid metallic nanocomposites are discussed. A comparison of glucose and H2O2 sensing parameters using the same electrode materials is outlined to predict the efficient sensing performance of advanced nanomaterials. Recent innovative approaches to improve the NEGH sensitivity, selectivity and stability in real-time applications are critically discussed, which have not been sufficiently addressed in the previous reviews. Finally, the challenges, future trends, and prospects associated with advanced nanomaterials for NEGH sensing are considered. We believe this article will help to understand the selection of advanced materials for dual/multi non-enzymatic sensing issues and will also be beneficial for researchers to make breakthrough progress in the area of non-enzymatic sensing of dual/multi biomolecules.
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Mechanism of the Oxidation of 3,3',5,5'-Tetramethylbenzidine Catalyzed by Peroxidase-Like Pt Nanoparticles Immobilized in Spherical Polyelectrolyte Brushes: A Kinetic Study.
Gu, S, Risse, S, Lu, Y, Ballauff, M
Chemphyschem : a European journal of chemical physics and physical chemistry. 2020;(5):450-458
Abstract
Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H2 O2 ) catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB-Pt). Due to the high stability of SPB-Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time-dependent concentration of the blue-colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H2 O2 and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir-Hinshelwood mechanism. A true rate constant k, characterizing the rate-determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase-like nanoparticles.
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Pre-magnetized Fe0 as heterogeneous electro-Fenton catalyst for the degradation of p-nitrophenol at neutral pH.
Tian, Y, Zhou, M, Pan, Y, Cai, J, Ren, G
Chemosphere. 2020;:124962
Abstract
Pre-magnetized Fe0 (Pre-Fe0) was for the first time applied as heterogeneous catalyst to enhance the oxidation efficiency of electro-Fenton (EF) for the degradation of p-nitrophenol (PNP). The parameters including current, initial pH and pre-Fe0 dosage of Pre-Fe0/EF process were optimized and compared with other two processes (conventional Fe0/EF and electro-oxidation) to confirm its advantage. The rate constants of PNP removal were 1.40-3.82 folds of those by Fe0/EF process under various experimental conditions. The application of pre-Fe0 as catalyst could extend the working pH range from 3.0 to neutral conditions for PNP removal and reduce the Fe0 dosage from 2 to 0.5 mM corresponding to Fe0/EF, avoiding the second pollution of iron sludge. The superiority of Pre-Fe0/EF process was also verified to improve the degradation and mineralization of other phenols and antibiotics. Furthermore, a possible pathway of PNP degradation was revealed by the identification of intermediates and organic acids, and the possible mechanism of pre-Fe0 efficiently enhanced the EF efficiency was proposed. This work demonstrated that such a novel heterogeneous EF process using pre-Fe0 catalyst was clean and promising for the degradation of refractory organic pollutants.
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Efficacy and safety of disinfectants for decontamination of N95 and SN95 filtering facepiece respirators: a systematic review.
O'Hearn, K, Gertsman, S, Webster, R, Tsampalieros, A, Ng, R, Gibson, J, Sampson, M, Sikora, L, McNally, JD
The Journal of hospital infection. 2020;(3):504-521
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BACKGROUND Decontaminating and reusing filtering facepiece respirators (FFRs) for healthcare workers is a potential solution to address inadequate FFR supply during a global pandemic. AIM: The objective of this review was to synthesize existing data on the effectiveness and safety of using chemical disinfectants to decontaminate N95 FFRs. METHODS A systematic review was conducted on disinfectants to decontaminate N95 FFRs using Embase, Medline, Global Health, Google Scholar, WHO feed, and MedRxiv. Two reviewers independently determined study eligibility and extracted predefined data fields. Original research reporting on N95 FFR function, decontamination, safety, or FFR fit following decontamination with a disinfectant was included. FINDINGS AND CONCLUSION A single cycle of vaporized hydrogen peroxide (H2O2) successfully removes viral pathogens without affecting airflow resistance or fit, and maintains an initial filter penetration of <5%, with little change in FFR appearance. Residual hydrogen peroxide levels following decontamination were within safe limits. More than one decontamination cycle of vaporized H2O2 may be possible but further information is required on how multiple cycles would affect FFR fit in a real-world setting before the upper limit can be established. Although immersion in liquid H2O2 does not appear to adversely affect FFR function, there is no available data on its ability to remove infectious pathogens from FFRs or its impact on FFR fit. Sodium hypochlorite, ethanol, isopropyl alcohol, and ethylene oxide are not recommended due to safety concerns or negative effects on FFR function.