Degradation Products Research Articles

Aging of microplastics and its photo-catalytic degradation of coexisting tetracycline

Photodegradation processes play a crucial role in the transforming of antibiotics in aqueous environments, while photochemical aging influences the properties of microplastics (MPs). In this study, the efficacy of ultraviolet (UV) irradiation in eliminating tetracycline (TC) was examined. Especially, TC degradation was mediated by polyethylene microplastics (PE-MPs) was subjected to aging through UV exposure and a combination of UV and thermal-activated persulfate treatments. The effects of MP concentration, salinity, and pH on TC degradation were investigated. The characteristics of aging PE-MPs and the corresponding active free radicals were analyzed to understand the mechanism of TC degradation. The results showed that the existence of PE-MPs significantly influenced TC degradation under photosensitized conditions. However, as the concentration of PE-MPs increased, the degradation rate initially increased and subsequently declined. TC degradation increased from approximately 35% to 85% when pH increased from 3 to 11 mediated by aged PE-MPs. Moreover, the TC degradation ability increased with increasing salinity, and a higher aging degree facilitated the photodegradation of TC, achieving a removal rate of 62 %. At the same time, free radical quenching confirmed that the singlet oxygen (1O2), hydroxyl radical (OH), and superoxide radical (O2·−) produced all involved in the photolysis process of TC mediated by PE-MPs, especially 1O2. The analysis of the degradation products of TC and prediction of its toxicity revealed that the ecological risk associated with the degradation solution diminished compared with that of the TC mother solution.

Transcriptomics revealed the key molecular mechanisms of ofloxacin-induced hormesis in Chlorella pyrenoidosa at environmentally relevant concentration

Emerging pollutants such as antibiotics have aroused great concern in recent years. However, the knowledge of low concentration-induced hormesis was not well understood. This study evaluated and quantified hormetic effects of ofloxacin on Chlorella pyrenoidosa. LogNormal model predicted the maximal non-effect concentration was 0.13 mg/L and 2.96 mg/L at 3 and 21 d, respectively. The sensitive alterations in chlorophyll fluorescence suggested PSII was the main target. Transcriptomics revealed ofloxacin inhibited genes related to photosynthetic system while the cyclic electron around PSI decreased the pH value in stroma side and stimulated photoprotection via up-regulating psbS. The stimulation in citrate cycle pathway met the urgent requirements of energy for DNA replication and repair. In addition, the negative feedback of G3P in glycolysis pathway inhibited Calvin cycle. The degradation products illustrated the occurrence of multiple detoxification mechanisms such as demethylation and ring-opening. The mobilization of cytochrome P450 generated the constant detoxication of ofloxacin while glutathione was consumptively involved in biological binding. This study provided new insights into the molecular mechanisms of antibiotic-induced hormesis in microalgae.

Effects of glyphosate on glyphosate‐resistant maize growth and metabolic parameters in the greenhouse and field

AbstractThe potential adverse effects of glyphosate on glyphosate‐resistant (GR) crops are still a matter of controversy. The effects of glyphosate at recommended application rates (either a single application of 580 g ae ha−1 of glyphosate at stage V5 or a sequential application of 580 + 980 g ae ha−1 at stage V3 and V7, respectively) on growth, mineral content, and metabolic parameters of GR maize (Zea mays) were determined in greenhouse and field studies, each replicated in different years. No effects on any growth parameter (including grain yield), mineral content (leaf and grain), grain starch, crude protein, or total lipids were found. The only significant negative effect was a slight reduction in tyrosine content of leaf tissue with the sequential treatment, however, there was no increase in shikimic or quinic acids in leaf tissue with any treatment. In a separate greenhouse experiment, there was no sign of oxidative stress, as determined by levels of chlorophylls, carotenoids, and malondialdehyde (MDA) content as well as superoxide dismutase and guaiacol peroxidase activities 4 and 8 days after treatment with 1080 g ha−1 glyphosate. In fact, there was a reduction of MDA in roots of glyphosate‐treated plants 4 DAT, indicating reduced oxidative stress. No aminomethylphosphonic acid, the primary degradation product of glyphosate, was found in either leaves or grain of treated plants, and no glyphosate was found in grain of treated plants from the field studies. All the results are consistent with there being no adverse effects of glyphosate on GR maize at recommended application rates.

Enhanced degradation of insoluble chitin: Engineering high-efficiency chitinase fusion enzymes for sustainable applications

N-acetyl-D-glucosamine and its dimer are degradation products of chitin waste with great potential in therapeutic and agricultural applications. However, the hydrolysis of insoluble chitin by chitinases remains a major bottleneck. This study investigated the biochemical properties and catalytic mechanisms of PoChi chitinase obtained from Penicillium oxalicum with a focus on enhancing its efficiency during the degradation of insoluble chitin. Recombinant plasmids were engineered to incorporate chitin-binding (ChBD) and/or fibronectin III (FnIII) domains. Notably, PoChi-FnIII-ChBD exhibited the highest substrate affinity (Km = 2.7 mg/mL) and a specific activity of 15.4 U/mg, which surpasses those of previously reported chitinases. These findings highlight the potential of engineered chitinases in advancing industrial biotechnology applications and offer a promising approach to more sustainable chitin waste management.

Degradation of the novel herbicide tiafenacil in aqueous solution: Kinetics, various influencing factors, hydrolysis products identification, and toxicity assessment

As new pesticides are continually introduced into agricultural systems, understanding their environmental behavior and potential toxicity effects is crucial for effective risk assessment. This study utilized QuEChERS and UPLC-QTOF-MS/MS techniques to analyze Tiafenacil (TFA) and its six hydrolysis products (HP1 to HP6) in water, marking the first comprehensive report on these degradation products. Calibration curves demonstrated strong linearity (R2 ≥ 0.9903) across concentrations ranging from 0.02 to 3.50 mg L−1. TFA's hydrolysis followed single first-order kinetic (SFOK) model, with rapid degradation observed under alkaline and high-temperature conditions, resulting in half-lives ranging from 0.22 to 84.82 days. The ECOSAR model predicts that TFA's hydrolysis products exhibit acute and chronic toxicity to fish, Daphnia, and green algae. Additionally, hydrolysis products HP1, HP5, and HP6 were detected in irrigation water from citrus orchards, posing higher predicted toxicity risks to fish and green algae. This highlights the necessity for further risk assessments considering transformation products. Overall, this study enhances our understanding of TFA's environmental fate and supports its safe agricultural application and monitoring practices.

Development and validation of stability indicating HPTLC method for estimation of Daclatasvir Dihydrochloride in pharmaceutical dosage form

A high-performance thin-layer chromatographic method was developed and validated for estimation of Daclatasvir Dihydrochloride in pharmaceutical dosage form. The proposed method was applied successfully to the pharmaceutical analysis of the recently approved dosage form of Daclatasvir Dihydrochloride which is available in market as a brand name of ‘NALDAC 60’ tablets. The drugs were satisfactorily show peak with RF 0.38 for Daclatasvir Dihydrochloride. Method was validated according to the ICH guidelines. The calibration plot was linear between 50-300 ng per band for Daclatasvir Dihydrochloride. The LOD and LOQ for Daclatasvir Dihydrochloride were found to be 0.171 μg per band and 0.521 μg per band, respectively. Accuracy and precision of the proposed method was evaluated by recovery studies (% recovery for Daclatasvir Dihydrochloride was 99.88%) and intra-day and inter-day precision studies (standard deviation value for precision studies was found to be 0.453). In stability testing, Daclatasvir Dihydrochloride was found susceptible to acid hydrolysis and alkaline degradation. Because the method could effectively separate the drugs from their degradation products, it can be used as a stability indicating method. The proposed validated stability indicating assay for the sensitive determination of the mentioned drugs is suitable for Quality control laboratories as a simple fast economic method. Degradation product of Daclatasvir Dihydrochloride in alkaline condition was carried out.

Handheld point-of-care devices for snakebite coagulopathy: a scoping review.

Venom induced consumption coagulopathy (VICC) is a common complication of snakebite that is associated with hypofibrinogenaemia, bleeding, disability, and death. In remote tropical settings, where most snakebites occur, the 20-minute whole blood clotting test is used to diagnose VICC. Point-of-care (POC) coagulation devices could provide an accessible means of detecting VICC that is better standardised, quantifiable, and more accurate. In this scoping review, the mechanistic reasons that previously studied POC devices have failed in VICC are considered, and evidence-based recommendations are made to prioritise certain devices for clinical validation studies. Four small studies have evaluated a POC international normalised ratio (INR) device in patients with Australian Elapid, Daboia russelii and Echis carinatus envenoming. All of these studies used POC INR devices that rely on a thrombin substrate endpoint, which, unlike laboratory-based INR measurement, is known to underestimate INR in patients with hypofibrinogenaemia. Seventeen commercially available POC devices for measuring INR, activated clotting time (ACT), activated partial thromboplastin time (aPTT), fibrinogen, D-dimer, and fibrin(ogen) degradation products (FDP) have been reviewed. POC INR devices that detect fibrin clot formation, as well as a novel POC device that quantifies fibrinogen were identified, that show promise for use in patients with VICC. These devices could support more accurate allocation of antivenom, reduce the time to antivenom administration, and provide improved clinical trial outcome measurement instruments. There is an urgent need for these promising POC coagulation devices to be validated in prospective clinical snakebite studies.

Infection, inflammation and hepatic encephalopathy from a clinical perspective.

Hepatic encephalopathy (HE) is a syndrome that is associated with both acute and chronic liver injury. It manifests as a wide spectrum of neuropsychological abnormalities, ranging from subtle impairments in executive higher functions observed in cirrhosis, through to coma in acute liver failure. In acute liver failure, the central role of ammonia in the development of brain oedema has remained undisputed for 130 years. It latterly became apparent that infection and inflammation were profound determinants for the development of severe hepatic encephalopathy, associated with the development of cerebral oedema and intracranial hypertension. The relationship of the development of hepatic encephalopathy with blood ammonia levels in cirrhosis is less clear cut and the synergistic interplay of inflammation and infection with ammonia has been identified as being fundamental in the development and progression of hepatic encephalopathy. A perturbed gut microbiome and the presence of an impaired gut epithelial barrier that facilitates translocation of bacteria and bacterial degradation products into the systemic circulation, inducing systemic inflammation and innate and adaptive immune dysfunction, has now become the focus of therapies that treat hepatic encephalopathy in cirrhosis, and may explain why the prebiotic lactulose and rifaximin are efficacious. This review summarises the current clinical perspective on the roles of inflammation and infection in hepatic encephalopathy and presents the evidence base for existing therapies and those in development in the setting of acute and chronic liver failure.

The solar/chlorine system degradation of iopamidol: Roles of reactive species, degradation pathway, and toxicity

The study systematically examined the changing trends of the percentage contributions of reactive species to the degradation of Iopamidol (IPM) under various conditions in the solar/chlorine system. Results showed that compared with chlorine alone and solar radiation system, the solar/chlorine system had an obvious effect on the degradation of IPM under control experiment conditions. HO• and reactive chlorine species played major roles in the apparent pseudo-first-order rate constants of IPM degradation (kobs). The increase of oxidant dosage significantly promoted the steady-state concentration of RCS and the contributions of those to kobs. The concentrations of various radicals at pH 9 were lower than those of at pH 5, while only the percentage contribution of ClO• on kobs was increased. The presence of Cl- could increase the steady-state concentration of Cl•, which further promoted the kobs. NOM would significantly reduce the steady-state concentration of ClO• and Cl•, which leads to a significant increase in the percentage contribution of Cl2−• to kobs, indicating the important role of Cl2−• on organic removal in real water. HCO3-/CO32- had almost no effect on kobs. The degradation products of IPM were identified through HPLC-MS, and the Fukui function was employed to ascertain the sites of degradation, which were formulated by deiodination reactions and the production of organic radicals. According to structure Activity Relationships Program v.2.2 and acute toxicological tests, byproducts did not exhibit significant toxicity. The findings illustrate that the solar/chlorine system is effective in decomposing IPM into non-toxic and non-hazardous small molecules, with potential applications.

Rapid identification of antibody impurities in size-based electrophoresis via CZE-MS generated spectral library

Methods for the reliable and effective detection and identification of impurities are crucial to ensure the quality and safety of biopharmaceutical products. Technical limitations constrain the accurate identification of individual impurity peaks by size-based electrophoresis separations followed by mass spectrometry. This study presents a size-based electrophoretic method for detecting and identifying impurity peaks in antibody production. A hydrogen sulfide-accelerated degradation method was employed to generate known degradation products observed in bioreactors that forms the basis for size calibration. LabChip GXII channel electrophoresis enabled the rapid (< 1 min) detection of impurity peaks based on size, while capillary zone electrophoresis-mass spectrometry (CZE-MS) facilitated their accurate identification. We combine these techniques to examine impurities resulting from cell culture harvest conditions and forced degradation to assess antibody stability. To mimic cell culture harvest conditions and the impact of forced degradation, we subjected samples to cathepsin at different pH buffers or exposed them to high pH and temperature. Our method demonstrated the feasibility and broad applicability of using a CZE-MS generated spectral library to unambiguously assign peaks in high throughput size-based electrophoresis (i.e., LabChip GXII) with identifications or likely mass of the antibody impurity. Overall, this strategy combines the utility of CZE-MS as a high-resolution separation and detection method for impurities with size-based electrophoresis methods that are typically used to detect (not identify) impurities during the discovery and development of antibody therapeutics.

Towards Reducing Food Wastage: Analysis of Degradation Products Formed during Meat Spoilage under Different Conditions.

Foodstuffs, particularly perishable ones such as meat, are frequently discarded once the best-before date has been reached, despite the possibility of their continued suitability for human consumption. The implementation of intelligent packaging has the potential to contribute to a reduction in food wastage by enabling the monitoring of meat freshness during storage time independently of the best-before date. The process of meat spoilage is associated with the formation of specific degradation products, some of which can be potentially utilized as spoilage indicators in intelligent packaging. The aim of the review is to identify degradation products whose concentration correlates with meat shelf life and to evaluate their potential use as spoilage indicators in intelligent packaging. To this end, a comprehensive literature research was conducted to identify the factors influencing meat spoilage and the eight key degradation products (carboxylic acids, biogenic amines, total volatile basic nitrogen, aldehydes, alcohols, ketones, sulfur compounds, and esters) associated with this process. These degradation products were analyzed for their correlation with meat shelf life at different temperatures, atmospheres, and meat types and for their applicability in intelligent packaging. The review provides an overview of these degradation products, comparing their potential to indicate spoilage across different meat types and storage conditions. The findings suggest that while no single degradation product universally indicates spoilage across all meat types and conditions, compounds like carboxylic acids, biogenic amines, and volatile basic nitrogen warrant further investigation. The review elucidates the intricacies inherent in identifying a singular spoilage indicator but underscores the potential of combining specific degradation products to expand the scope of applications in intelligent packaging. Further research (e.g., storage tests in which the concentrations of these substances are specifically examined or research on which indicator substance responds to these degradation products) is recommended to explore these combinations with a view to broadening their applicability.

Fungal Enzyme-Responsive Hydrogel Drug Delivery Platform for Triggered Antifungal Release.

Fungal infections can lead to debilitating consequences if they are not treated effectively. Antifungal drugs used to treat these infections can be toxic and overuse contributes to growing antifungal resistance. Candida spp., particularly C. albicans, are implicated in a majority of these infections. Virulent C. albicans produce secreted aspartic proteases (Saps) that aid in pathogen tissue invasion and proliferation at an infected site. Here, fungi-responsive hydrogels are developed that degrade in the presence of Saps to provide a triggered release of encapsulated liposomal antifungals. The hydrogel backbone incorporates a Sap-cleavable peptide sequence enabling Sap-responsive degradation. Hydrogels are found to effectively degrade in the presence of Saps extracted from C. albicans. Encapsulated liposomal antifungals show similar release kinetics as hydrogel degradation products in the presence of Saps, supporting a degradation-dependent release mechanism. Antifungal liposome-loaded responsive hydrogels exhibit successful eradication of C. albicans cultures and remain stable in sterile murine wound fluid. Finally, no significant cytotoxicity is observed for murine fibroblast cells and red blood cells exposed to hydrogel degradation products. These fungi-responsive hydrogels have the potential to be used for local, on-demand delivery of antifungal drugs, for effective treatment of fungal infections while helping to limit unnecessary exposure to thesetherapeutics.

An Advanced Solvent for the Caustic-Side Solvent Extraction of Cesium from Nuclear Waste: Comparing Lipophilic Guanidines for Improved Hydrolytic Stability

ABSTRACT An advanced solvent has been developed for application in the extraction of cesium from alkaline nuclear waste. Four lipophilic guanidines have been compared to arrive at a more hydrolysis-resistant suppressor component of the solvent. Plans call for deployment of the Next-Generation Caustic Side-Solvent Extraction (NG-CSSX) process at industrial scale for separation of radioactive Cs-137 from the legacy salt waste stored at the US Department of Energy Savannah River Site (SRS). In the solvent used in NG-CSSX, an alkyl guanidine “suppressor” component facilitates efficient stripping of the loaded cesium from the solvent. However, as typical of guanidine compounds, the suppressor previously used in the NG-CSSX solvent, N,N‘,N’’-tri(3,7-dimethyloctyl)guanidine (TiDG), suffers from hydrolytic degradation under process conditions. Recently, the sterically hindered alkyl guanidine N,N’-dicyclohexyl-N’’-(10-nonadecyl)guanidine (DCNDG) has been found to offer 8 to 44 times greater hydrolysis resistance than TiDG. Here, the process performance characteristics of the NG-CSSX solvent incorporating DCNDG are determined in comparison with TiDG and two other guanidine suppressors. The solvent has been adjusted in density to accommodate use in the SRS Salt Waste Processing Facility and tested under aggressive bench-scale conditions intended to increase plant throughput. Experiments include the effect of ageing at normal and off-normal temperatures of the distribution of Cs+ through the NG-CSSX process, the fate and effects of guanidine degradation products, suppressor capacity, coalescence times for aqueous-solvent dispersions, tendency for emulsification, third-phase formation, and degree of protonation of the guanidine in stripping. While the chosen structures of the four compared guanidines mainly effect differences in stability, subtle differences in other system properties such as emulsion formation and suppressor capacity provide insight into the function of this important solvent component. In comparison with TiDG and two other guanidines, DCNDG provides greatly increased stability while not compromising the excellent functional properties of the NG-CSSX solvent.

Breaking the Perfluorooctane Sulfonate Chain: Piezocatalytic Decomposition of PFOS Using BaTiO3 Nanoparticles

Per‐ and polyfluoroalkyl substances (PFAS) pose significant environmental and health risks due to their ubiquitous presence and persistence in water systems. Herein, the efficacy of piezocatalysis using barium titanate nanoparticles under ultrasound irradiation for the degradation and defluorination of perfluorooctane sulfonate (PFOS) in water is investigated. The research demonstrates a substantial 90.5% degradation and 29% defluorination of PFOS after 6 h of treatment, highlighting the potential of piezocatalysis as a promising approach for PFAS degradation. Additionally, the quantification of degradation products elucidates the transformation pathways of PFOS, suggesting a stepwise chain‐shortening mechanism. The findings underscore the importance of continued research in optimizing piezocatalytic processes and exploring synergistic approaches with other advanced oxidation methods to effectively address PFAS contamination challenges. These efforts are essential for advancing sustainable water treatment strategies and mitigating the environmental and health hazards associated with PFAS contamination.

Exploring the Prospects and Challenges of Fluorine-Free Firefighting Foams (F3) as Alternatives to Aqueous Film-Forming Foams (AFFF): A Review.

This review provides a comparative analysis of the performance, toxicity, environmental impact, and health risks associated with fluorotelomer-based/short-chain AFFF and F3. Despite notable progress in F3 development, achieving comparable performance remains challenging in some cases. F3 formulations, while promising, are yet to be considered a direct replacement for AFFF in all Class B fire suppression scenarios due to variations in their performance across different fuel types and test conditions. Available studies indicate that commercially available F3 exhibit greater biodegradability and reduced environmental persistence compared to AFFF. However, some alternatives may still pose similar environmental impacts. Limited ecotoxicity studies suggest that some F3 may exhibit equal or even higher toxicity to aquatic species than short-chain (C6) AFFF. Toxicological assessments and risk evaluations of F3 should consider factors beyond environmental persistence, including acute and chronic ecotoxicity, potential endocrine disruption, and the full toxicological profile of foam formulations and their individual components. Further research is necessary to understand the fate, transport, bioaccumulation, and toxicity of F3 degradation products. Addressing these knowledge gaps is crucial to ensure the safe and sustainable implementation of F3 as an alternative fire suppression solution.

Thevetia thevetioides Cardenolide and Related Cardiac Glycoside Profile in Mature and Immature Seeds by High-Resolution Thin-Layer Chromatography (HPTLC) and Quadrupole Time of Flight-Tandem Mass Spectrometry (Q-TOF MS/MS) Reveals Insights of the Cardenolide Biosynthetic Pathway.

Thevetia thevetioides is a species within the Apocynaceae family known for containing cardenolide-glycosides, commonly referred to as cardiac glycosides, which are characteristic of this genus. The seeds of the Thevetia species are frequently used as a model source for studying cardiac steroids, as these glycosides can be more readily extracted from the oil-rich seeds than from the plant's green tissues. In this work, the cardenolide profile of ripe and immature seeds was determined and compared to establish the main differences. Ripe seeds contain six related cardenolides and triosides, with thevetin B being the predominant component. In contrast, immature seeds exhibit a total of thirteen cardiac glycosides, including monoglycosides such as neriifolin and peruvosides A, B, and C, as well as diglycosides like thevebiosides A, B, and C. Some of these compounds have previously been identified as degradation products of more complex cardiac glycosides; however, their presence in immature seeds, as described in this study, suggests that they may serve as biosynthetic precursors to the triosides observed in mature seeds. The glycoside patterns observed via HPTLC are associated with specific chemical structures characteristic of this genus, typically featuring thevetose or acetyl-thevetose at the first position, followed by glucose or gentibiose in di- or trisaccharides, independent of the trioside aglycones identified: digitoxigenin, cannogenin, or yccotligenin. Ripe seeds predominantly contain triosides, including thevetin B, C, and A, the latter of which has not been previously reported.

Green synthesis of Bio-CuS quantum dots by sulfate reducing bacteria for solid-phase photocatalytic degradation of polyethylene film

In this study, CuS quantum dots (QDs) synthesized through biological method were used as photocatalysts for the photocatalytic degradation of polyethylene (PE) plastics. Bio-CuS QDs were synthesized through a green process using sulfate reducing bacteria, while Che-CuS QDs were prepared by chemical precipitation for comparison. The crystal structure, surface morphology, microstructure and optical properties of the samples were detected by XRD, SEM, TEM and UV–Vis DRS. The green synthesis mechanism of Bio-CuS was inferred by analyzing changes in amino acid concentration and the three-dimensional fluorescence spectra of extracellular polymeric substances before and after synthesis. The photocatalytic degradation of PE films by Che-CuS and Bio-CuS was investigated. The weight loss rates of PE+Che-CuS and PE+Bio-CuS were 9.1 % and 12.8 % after 14 d irradiation, respectively, while pure PE was only 1.7 %. Furthermore, SEM, UV–Vis DRS, contact angle, TGA, GPC and FTIR were adopted to characterize the PE film. The results revealed that PE+Che-CuS and PE+Bio-CuS underwent major changes in morphology, transparency, hydrophilicity, thermal stability, molecular weight and functional groups compared with PE, with more pronounced changes observed for PE+Bio-CuS. The quenching experiments of active species showed that h+ and·OH were critical to the PE degradation. The intermediate products of PE degradation were analyzed by GC–MS, and a possible degradation pathway was proposed. In addition, the possible mechanism of photocatalytic degradation of PE films by CuS QDs was proposed. This work provides a green remediation approach to addressing the growing plastic pollution in the environment.

Design, development and characterization of a chimeric protein with disulfide reductase and protease domain showing keratinase activity

Keratin is one of the major components of solid waste, and the degradation products have extensive applications in various commercial industries. Due to the complexity of the structure of keratin, especially the disulfide bonds between keratin polypeptides, keratinolytic activity is efficient with a mixture of proteins with proteases, peptidases, and oxidoreductase activity. The present work aimed to create an engineered chimeric protein with a disulfide reductase domain and a protease domain connected with a flexible linker. The structure, stability, and substrate interaction were analyzed using the protein modeling tools and codon-optimized synthetic gene cloned, expressed, and purified using Ni2+-NTA chromatography. The keratinolytic activity of the protein was at its maximum at 70 °C. The suitable pH for the enzyme activity was pH 8. While Ni2+, Mg2+, and Na+ inhibited the keratinolytic activity, Cu2+, Ca2+, and Mn2+ enhanced it significantly. Biochemical characterization of the protease domain indicated significant keratinolytic activity at 70 °C at pH 10.0 but was less efficient than the chimeric protein. Experiments using feathers as the substrate showed a clear degradation pattern in the SEM analysis. The samples collected from the degradation experiments indicated the release of proteins (2-fold) and amino acids (8.4-fold) in a time-dependent manner. Thus, the protease with an added disulfide reductase domain showed excellent keratin degradation activity and has the potential to be utilized in the commercial industries.

Protein S contributes to the paradoxical increase in thrombin generation by low-dose dabigatran in the presence of thrombomodulin.

Low dose of dabigatran paradoxically increased thrombin generation through inhibition of protein C activation. Protein S is a co-factor in the activation of protein C. However, the role of protein S in the enhancement of thrombin generation has not been addressed. Firstly, we measured thrombin generation by calibrated automated thrombinography (CAT) and prothrombin fragments 1+2 (F1+2) assays. Secondly, we assessed activated protein C (APC) formation in normal or protein S-deficient plasma spiking with dabigatran. Then, protein C activation was measured. Finally, heavy chain of factor Va (FVa) and its degradation products were detected by western blot. CAT assay showed that 70-141 ng/ml dabigatran paradoxically increased thrombin generation in normal plasma. However, higher concentrations of dabigatran (283 ng/ml) suppressed the level of ETP. F1+2 assay showed the similar results. In protein S-deficient or protein C-deficient plasma, the paradoxical increase in thrombin generation was absent. Level of generated APC was to a similar extent inhibited by dabigatran in normal and protein S-deficient plasma. Low-dose dabigatran inhibited the protein S-dependent inactivation of factor Va. Protein S participated in the paradoxical enhancement of thrombin generation in normal plasma spiking with low concentrations of dabigatran. Increased thrombin generation at low dabigatran can be explained by reduced thrombin-thrombomodulin mediated APC formation and subsequent reduced FVa inactivation that is protein S-dependent.

Waste control by waste: A new approach for antibiotic removal and metal reuse from livestock wastewater using ascorbic acid-enhanced CaO2/Cu(II) system

Aiming at the coexistence of antibiotics and Cu(II) in livestock wastewater, a novelty strategy for the simultaneous removal of antibiotics and Cu ions by in-situ utilization of Cu(II) (i.e., CP/Cu(II) and CP/Cu(II)/ascorbic acid (AA) systems) was proposed. The removal rate of florfenicol (FF) in the CP/Cu(II)/AA system was 6.9 times higher than that of the CP/Cu(II) system. CP/Cu(II)/AA system was also effective in removing antibiotics from real livestock tailwater. Simultaneously, the removal of Cu ions in CP/Cu(II) and CP/Cu(II)/AA systems could reach 54.5 % and 15.7 %, respectively. The added AA could significantly enhance the antibiotics degradation but inhibit the Cu ions removal. HO•, O2•-, Cu(III), and •C-R were detected in the CP/Cu(II)/AA system, in which HO• was confirmed as the predominant contributor for FF degradation, and Cu(III) and •C-R also participated in FF elimination. The role of AA could accelerate HO• production and Cu(I)/Cu(II)/Cu(III) cycle, and form •C-R. The degradation products and pathways of FF in the CP/Cu(II)/AA system were proposed and the toxicity of the degradation products was evaluated by the toxicity analysis software (T.E.S.T). The results of this work suggest that without introducing complex catalysts, the feasibility of in-situ utilization of Cu(II) inherently or artificially introduced in livestock wastewater activating CP for antibiotic degradation and Cu ions removal was verified.