[Migration, Transformation, and Toxicity of Quaternary Ammonium Antimicrobial Agents in the Environment].

Quaternary ammonium compounds (QACs) are one type of widely used cationic biocide, and their usage amount is growing rapidly due to the flu and COVID-19 pandemic. Many QACs were released into the environment in or after the course of their use, and thus they were widely detected in water, sediment, soil, and other environmental media. QACs have stronger surface activity and non-specific biotoxicity, which poses a potential threat to the ecosystem. In this study, the environmental fate and potential toxicity of QACs were documented in terms of their migration and transformation process, biological toxicity effects, and the main mechanisms of bacterial resistance to QACs. Aerobic biodegradation was the main natural way of eliminating QACs in the environment, and the reaction was mainly initiated by the hydroxylation of C atoms at different positions of QACs and finally mineralized to CO2and H2O through decarboxylation, demethylation, and ß-oxidation reaction. Toxicological studies showed that QACs at environmental concentrations could not pose acute toxicity to the selected biotas but threatened the growth and reproduction of aquatic organisms like Daphnia magna. Their toxicity effects depended on their molecular structure, the tested species, and the exposed durations. Additionally, our team first investigated the toxicity effects and mechanisms of QACs toward Microcystis aeruginosa, which showed that QACs depressed the algae growth through the denaturation of photosynthetic organelles, suppression of electron transport, and then induction of cell membrane damage. In the environment, the concentrations of QACs were always lower than their bactericidal concentrations, and their degradation could induce the formation of a concentration gradient, which facilitated microbes resistant to QACs. The known resistance mechanisms of bacteria to QACs mainly included the change in cell membrane structure and composition, formation of biofilm, overexpression of the efflux pump gene, and acquisition of resistance genes. Due to the similar targets and mechanisms, QACs could also induce the occurrence of antibiotic resistance, mainly through co-resistance and cross-resistance. Based on the existing data, future research should emphasize the toxicity effect and the potential QACs resistance mechanism of microorganisms in real environmental conditions.

Interlayer adsorption of cationic dye on cationic surfactant-modified and unmodified montmorillonite.

Water pollution by toxic organic dyes is one of the most critical health and environmental problems worldwide. By means of molecular dynamics method, the present work aims to evaluate the applicability of montmorillonite (Mt) modified by hexadecyltrimethylammonium cations (HDTMA+) compared to unmodified Na-Mt for the adsorption of cationic methylene blue (MB) dye. The results showed that the adsorption energy of MB on both HDTMA-Mt and Na-Mt absorbent ranged from - 100 to - 250 kJ/mol, indicating the effectiveness of two types of adsorbents in dye water treatment. The highest adsorption energy was found at w = 50% in each adsorbent system. Adsorption mechanisms of MB depend on molecular orientations, which is influenced by the surfactant and water content. The adsorption mechanism of MB is chemisorption dominated by strong electrostatic interaction between CH3 groups of MB and oxygen atoms of Mt surfaces. Besides, physisorption also plays a minor role in MB orientations. It is found that the existence of cationic surfactants can slightly improve the adsorption capacity of MB only at higher water content through enlarging the interlayer space of Mt and reducing mobility of MB. However, there will be a negative impact on the reduction of adsorption sites for dyes especially at low water content. Our results provide a possible application for swelling clay minerals being a promising adsorbent for dyes-surfactants co-existing wastewater treatment.

[Preventive and therapeutic effects of recombinant IFN-alpha2b nasal spray on SARS-CoV infection in Macaca mulata].

OBJECTIVE: To study the preventive and therapeutic effects of recombinant IFN-alpha2b for nasal spray on SARS-CoV infection in Macaca mulata (rhesus monkey). METHODS: Ten rhesus monkeys were divided into two groups, 5 in interferon group, and 5 in control group. Before and after SARS-CoV attack, the virus was detected in samples such as pharyngeal swab in all the two groups by Real-time PCR (RT-PCR) and virus isolation was performed. RESULTS: After virus attack, the level of SARS-CoV-specific IgG and neutralizing antibody were induced by SARS-CoV in the interferon group was weaker than in control group. Hematology items showed no apparent changes after virus attack in treated group. Through pathological examination, the morphology of the lung tissues of two Macaques in the treated group was normal, while the other three displayed the interstitial pneumonia with the thickened septum and infiltration with mononuclear cells. Among which, one monkey showed part of thickened septum fused with each other. These lesions in the interferon treated animals were similar to those seen in the animals in control group, but with smaller scope of pathological changes. No significant abnormity was detected in other organs. CONCLUSION: Recombinant IFN-alpha2b could effectively interdict or weaken SARS-CoV injury in monkeys.

[A field trial of recombinant human interferon alpha-2b for nasal spray to prevent SARS and other respiratory viral infections].

OBJECTIVE: To study the preventive effect of recombinant human interferon alpha-2b for nasal spray against SARS and other common respiratory viral infections by serum-epidemiological method. METHODS: A randomized, placebo-controlled, double-blind field trial study in populations with 14,391 persons from SARS prevalent cities or provinces in China during May-Jun, 2003 and Dec-Apr, 2004. Interferon alpha-2b was given twice per day, once 9 x 10(5) IU by nasal spray for 5 days. Serum samples were taken at 15 days after last administration. Serological tests included SARS IgG antibody and IgM antibodies against influenza B, parainfluenza virus types 1-3, adenovirus type 3, 7 and respiratory syncytial virus by using commercial ELISA kits. RESULTS: No statistically significant difference in serum SARS IgG antibody positive rate was found between the interferon and control groups among 2,757 serum samples. On the other hand, after using interferon, all four respiratory viruses (parainfluenza virus types 1-3 influenza B, adenovirus types 3, 7 and respiratory syncytial virus) in interferon group had lower IgM antibody positive rates than those in control group. Among them there were statistically significant differences between the interferon and control groups for parainfluenza virus, influenza B and adenovirus. The preventive efficacy of interferon against four respiratory viruses was different, from high to low, the rank was Flu B (66.76%), parainfluenza types 1-3 (66.75%), RSV (39.61%) and adenovirus (32.86%). The average preventive efficacy was 50.27%. CONCLUSION: The recombinant human interferon alpha-2b for nasal spray could decrease the rates of common respiratory viruses infection in the selected population.

[Preliminary study on nasal spray of interferon alpha-2b used for prevention of rubella and measles virus infections].

OBJECTIVE: To evaluate the efficacy of the interferon alpha-2b nasal spray in prevention of rubella and measles virus infections. METHODS: The properly selected volunteer groups have been divided into interferon alpha-2b experimental and control group. The experimental group received interferon alpha-2b treatment by nasal spray for 2 days before the immunization, then both groups were challenged with rubella and measles attenuated live vaccine respectively through nasal spray. The sera from pre-immunization and 21 and 28 days after immunization were collected to test the IgG antibody titers. The influence on the viral antibody titer reflects the viral preventive effect by interferon alpha-2b. RESULTS: The antibody titer difference of measles virus between experimental and control group was 1.26 (21 day) and 2.96 (28 day), there were statistically difference between them; the difference of rubella virus was 0.95 (21 day) and 0.37 (28 day), but there were no statistically differences found. CONCLUSION: The preliminary results showed that the interferon alpha-2b can be used as prevention method for measles and rubella viral infections.

[A field trial for evaluating the safety of recombinant human interferon alpha-2b for nasal spray].

OBJECTIVE: To evaluate the safety of recombinant human interferon alpha-2b for nasal spray for the prevention of SARS and other upper respiratory viral infections. METHODS: Field epidemiologic evaluation was conducted, the design was randomized and had a synchronously parallel control group. In the study, the drugs were given for five days and all subjects were followed up for ten days. RESULTS: During the period of using interferon, body temperature of the experimental group was normal compared to the control group. Experimental group had more influenza-like symptoms than the control group (P < 0.05), such as headache (4.83%-7.09%), dizziness (7.17%-11.63%), lassitude (8.55%-15.06%), muscular soreness (4.43%-7.09%), pharynx dryness (12.10%-17.85%), angina (6.25%-8.72%), abdominal pain (2.30%-5.50%) and diarrhea (2.45%-5.66%). Most of side effects reached their peak with in the first 3 days. Except for pharynx dryness, the incidences of all other side effects declined after completion of the use of the trial drug, and incidences of some symptoms in experimental group were lower than those of the control group. There were no significant differences in the symptoms of cough and expectoration between the experimental group and the control group. The incidence of exanthem in the control group was significantly higher than that in the experimental group. The side effect of bloody nasal mucus was not observed in experimental group, which had been reported by other authors in several volunteer studies. CONCLUSION: Using recombinant human interferon alpha-2b for nasal spray could lead to some influenza-like symptoms, however, all those symptoms were mild , reversible, and relieved after completion of the use of the trial drug. No serious side effects were found during the period of following up. The authors conclude that the drug is safe.

[Development of the cDNA chip for SARS virus and a primary study on the possible molecular mechanism of interferon alpha2b inhibiting the SARS virus replication].

BACKGROUND: To study the molecular mechanism of interferon alpha2b(IFNalpha2b) inhibiting the SARS virus replication. SARS-associated coronavirus (SARS virus) cDNA chip was developed and applied to detect the virus RNA transcription levels in the interferon-treated and untreated cell cultures, and the mechanism of anti-SARS virus activity of interferon alpha2b in cell culture system was explored. METHODS: SARS virus cDNA chip was prepared by comparing the published SARS virus genome sequence, and the cDNA chip was used to study the interferon alpha2b function during SARS virus replication. RESULTS: SARS virus cDNA chip was successfully prepared by using PCR method. The results showed that the cDNA chip could be used to detect the viral RNA transcription level. Interferon alpha2b could inhibit almost all the SARS virus gene transcription. An unknown gene at the position 28130-28426 bp, named as U gene, may play an important role during the viral replication. CONCLUSION: A SARS virus whole genome cDNA chip was established. It could be used to study the virus molecular biology and antiviral drug screening. The results also showed that interferon alpha2b could inhibit almost the whole virus gene transcription by using the cDNA chip.

[Anti-SARS virus activities of different recombinant human interferons in cell culture system].

BACKGROUND: To study the anti-SARS virus activities of different recombinant human interferons on the cell culture system. METHODS: Anti-SARS virus activities of interferons were determined by using CPE inhibition test in human skeletal muscle sarcoma (Rda) cell culture. RESULTS: The average minimum amount of interferon alpha 2b, alpha 1b, beta 1b or omega 1b to inhibit 50% CPE in Rda cell culture was (160.5+/-129.5) IU/ml, (149.0+/-71.7) IU/ml, (69.5+/-61.5) IU/ml, (87.3+/-47.1) IU/ml, respectively or (0.6+/-0.5) ng/ml, (10.6+/-5.1) ng/ml, (3.5+/-3.1) ng/ml, (0.9+/-0.5) ng/ml, respectively. CONCLUSION: All the tested recombinant interferons showed anti-SARS virus activities on the Rda cell culture with different sensitivities.