Analysis of sterilization efficiency and application cost of three low temperature sterilization methods.

OBJECTIVE: This paper discusses the sterilization efficiency of three low temperature sterilization methods used in thermosensitive medical devices and makes a preliminary analysis of sterilization costs so as to provide the basis for reasonable selection of low temperature sterilizer in Central Sterile Supply Department. METHODS: Medical devices compatible with the three sterilization methods were selected for sterilization, and two packaging materials were selected for the three low-temperature sterilization equipment according to the compatibility of the packaging materials. The equipment packed with the same packaging materials were sterilized for five times, and each low-temperature sterilizer was sterilized for a total of ten times. The sterilization effect, sterilization cycle time, energy consumption, and cost of the three sterilizers were compared. RESULTS: The cycle time of ethylene oxide sterilizer was 393.6 min, and the cycle time of hydrogen peroxide low temperature plasma sterilizer was 56.1 min. The cycle time of low temperature steam and formaldehyde sterilizer was 105.7 min. The hydrogen peroxide low temperature plasma sterilizes single cycle power consumption at a maximum of 5 kWh. The single cycle energy consumption of compressed air ethylene oxide sterilizer is up to 12 l. In terms of sterilization application cost, hydrogen peroxide low temperature plasma sterilization has the highest cost, followed by ethylene oxide sterilization, and low temperature steam and formaldehyde sterilization is the lowest. CONCLUSION: The sterilization efficiency of hydrogen peroxide low temperature plasma sterilization is the highest, followed by low temperature steam and formaldehyde sterilization, and the lowest is ethylene oxide sterilization. The three low temperature sterilization methods can achieve effective sterilization of devices. Each hospital can choose an appropriate low temperature sterilization method according to the characteristics of thermosensitive instruments, turnover efficiency requirements, and financial status.

Generation of a porcine reproductive and respiratory syndrome virus expressing a marker gene inserted between ORF4 and ORF5a.

In recent years, the availability of reverse genetics systems for porcine reproductive and respiratory syndrome virus (PRRSV) has created new perspectives for the use of recombinant viruses as expression vectors. Most of these recombinant PRRSV vectors express foreign genes through either an independent transcription unit inserted in ORF1b and ORF2, or in ORF7 and the 3' UTR. The aim of this study was to find an alternative site for foreign gene insertion into the PRRSV genome. Here, we constructed an infectious cDNA clone for a cell-adapted PRRSV strain, GXNN1396-P96. This cDNA-clone-derived recombinant virus (rGXAM) was comparable in its growth kinetics in MARC-145 cells to the parental virus, GX1396-P96. Using the infectious cDNA-clone, we inserted an independent transcription unit in ORF4 and ORF5a to generate a novel PRRSV-based recombinant virus expressing the green fluorescent protein (GFP) gene. Biological characterization of the recombinant virus, rGX45BSTRS-GFP, showed that it maintained similar growth characteristics but produced fewer infectious virions than the parental PRRSV. These data demonstrate that the ORF4 and ORF5a site is able to tolerate the insertion of foreign genes.

New insight into the binding modes of TNP-AMP to human liver fructose-1,6-bisphosphatase.

Human liver fructose-1,6-bisphosphatase (FBPase) contains two binding sites, a substrate fructose-1,6-bisphosphate (FBP) active site and an adenosine monophosphate (AMP) allosteric site. The FBP active site works by stabilizing the FBPase, and the allosteric site impairs the activity of FBPase through its binding of a nonsubstrate molecule. The fluorescent AMP analogue, 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-monophosphate (TNP-AMP) has been used as a fluorescent probe as it is able to competitively inhibit AMP binding to the AMP allosteric site and, therefore, could be used for exploring the binding modes of inhibitors targeted on the allosteric site. In this study, we have re-examined the binding modes of TNP-AMP to FBPase. However, our present enzyme kinetic assays show that AMP and FBP both can reduce the fluorescence from the bound TNP-AMP through competition for FBPase, suggesting that TNP-AMP binds not only to the AMP allosteric site but also to the FBP active site. Mutagenesis assays of K274L (located in the FBP active site) show that the residue K274 is very important for TNP-AMP to bind to the active site of FBPase. The results further prove that TNP-AMP is able to bind individually to the both sites. Our present study provides a new insight into the binding mechanism of TNP-AMP to the FBPase. The TNP-AMP fluorescent probe can be used to exam the binding site of an inhibitor (the active site or the allosteric site) using FBPase saturated by AMP and FBP, respectively, or the K247L mutant FBPase.

Synthesis and biological evaluation of novel inhibitors against 1,3,8-trihydroxynaphthalene reductase from Magnaporthe grisea.

1,3,8-Trihydroxynaphthalene reductase (3HNR) is an essential enzymes that is involved in fungal melanin biosynthesis. Based on the structural informations of active site of 3HNR, a series of ß-nitrostyrene compounds were rationally designed and synthesized. The enzymatic activities of these compounds showed that most of them exhibited high inhibitory activities (<5.0 µM) against 3HNR; compound 3-2 exhibit the highest inhibitory activity (IC50=0.29 µM). In particular, some of these compounds had moderate fungicidal activity against Magnaporthe grisea. Compound 3-4 showed high in vivo activities against M. grisea (EC50=9.5 ppm). Furthermore, compound 3-2 was selected as a representative molecule, and the probable binding mode of this compound and the surrounding residues in the active site of 3HNR was elucidated by using molecular dock. The positive results suggest that ß-nitrostyrene derivatives are most likely to be promising leads toward the discovery of novel agent of rice blast.