Cytosine deaminase (CD) converts 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) in CD/5-FC gene therapy, 5-FU will be mostly converted into nontoxic beta-alanine without uracil phosphoribosyltransferase (UPRT). UPRT catalyzes the conversion of 5-FU to 5-fluorouridine monophosphate, which directly kills CD::UPRT-expressing cells and surrounding cells via the bystander effect. But the pharmacokinetics and the bystander effect of CD::UPRT/5-FC has not been verified in vivo and in vitro. Before the CD::UPRT/5-FC bi-gene therapy system is used in clinical trial, it is essential to monitor the transgene expression and function in vivo. Thus, we developed a preclinical tumor model to investigate the feasibility of using (19)F-magnetic resonance spectroscopy ((19)F-MRS) and optical imaging to measure non-invasive CD and UPRT expression and its bystander effect.C6 and C6-CD::UPRT cells were cultured with 5-FC. The medium, cells and their mixture were analyzed by (19)F-MRS. Rats with intracranial xenografted encephalic C6-CD::UPRT glioma were injected intraperitoneally with 5-FC and their (19)F-MRS spectra recorded. Then the pharmacokinetics of 5-FC was proved. Mixtures of C6 and C6-CD::UPRT cells at different ratios were cultured with 5-FC and the cytotoxic efficacy and survival rate of cells recorded. To determine the mechanism of the bystander effect, the culture media from cell comprising 25% and 75% C6-CD::UPRT cells were examined by (19)F-MRS. A comparative study of mean was performed using analysis of variance (ANOVA).(19)F-MRS on samples from C6-CD::UPRT cells cultured with 5-FC showed three broad resonance signals corresponding to 5-FC, 5-FU and fluorinated nucleotides (F-Nuctd). For the C6 mixture, only the 5-FC peak was detected. In vivo serial (19)F-MRS spectra showed a strong 5-FC peak and a weak 5-FU peak at 20 minutes after 5-FC injection. The 5-FU concentration reached a maximum at about 50 minutes. The F-Nuctd signal appeared after about 1 hour, reached a maximum at around 160 minutes, and was detectable for several hours. At a 10% ratio of C6-CD::UPRT cells, the survival rate was (79.55 +/- 0.88)% (P < 0.01). As the C6-CD::UPRT ratio increased, the survival rate of the cells decreased. (19)F-MRS showed that the signals for 5-FU and F-Nuctd in the culture medium increased as the ratio of C6-CD::UPRT in the mixture increased.(19)F-MRS studies indicated that C6-CD::UPRT cells could effectively express CD and UPRT enzymes. The CD::UPRT/5-FC system showed an obvious bystander effect. This study demonstrated that CD::UPRT/5-FC gene therapy is suitable for 5-FC to F-Nuctd metabolism; and (19)F-MRS can monitor transferred CD::UPRT gene expression and catalysis of substrates noninvasively, dynamically and quantitatively.
Iron-loaded granular activated carbon (Fe-GAC) was prepared, characterized, and its performance as a catalyst in the Fenton oxidation of tetracycline (TC) was compared with that of carbon grains without iron supplementation. The characterization results revealed that the Fe 2+ was successfully introduced onto the original granular activated carbon (GAC) and diversified the surface morphology and elemental compounds of materials. Adsorption tests confirmed that the adsorption of TC on both materials can be described using pseudo-second-order kinetic model and Langmuir isotherm model. The response characteristics and influencing factors of degradation of TC in two systems were evaluated. TC removal over 60min at pH 3 was 89.5% for the GAC/Fenton system and 92.6% for the Fe-GAC/Fenton system.Moreover, the Fe-GAC/Fenton system displayed a lower Fe 2+ dosage than that of GAC/Fenton (an Fe 2+ /H 2 O 2 molar ratio of 0.04:1 versus 0.007:1). Excitation-emission matrix fluorescence spectroscopy showed that Fe-GAC/Fenton system delivered better mineralization, at least with TC. Fourteen intermediates were detected using quadrupole time-of-flight liquid chromatography coupled with mass system, and three possible degradation pathways for TC are proposed. Catalyst regeneration treatments was evaluated over six cycles. The regeneration was 6.5% more effective with the iron-supplemented carbon granules.
The current waste treatment techniques in developing countries do not meet the standards of appropriate waste management systems. Poor waste management leads to serious environmental issues at the local and global levels, for which an effective and sustainable waste disposal system is in urgent need. Due to its proven waste degradation and biotransformation capabilities, the Black Soldier Fly (BSF) provides a potential and economical alternative to recycling biological waste. The current study investigated the interactions between municipal and organic waste with the help of Black Soldier Fly Larvae (BSFL) as a growing medium for substrate culture by comparing the physicochemical parameters of waste before and after BSFL treatment of municipal and organic waste. The study results revealed that BSFL can improve the quality of the final product and promote the degradation of organic waste, although BSFL cannot effectively directly degrade municipal solid waste, it can reduce municipal solid waste by efficiently degrading organic waste. The optimal environmental conditions for BSFL breeding and growth was summarized in this study, and the environmental conditions of four seasons of four representative cities in different location of Pakistan were collected and analyzed. The most suitable cities for the development of the BSFL waste treatment system were first inferred, which makes basic research for developing an economical and feasible waste treatment system in Pakistan. A comprehensive legal framework regarding integrated MSW management systems should be introduced and implemented in Pakistan, including that local municipal authorities should collect the waste collection fee.
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