Aeration time following ethylene oxide sterilization for reusable rigid sterilization containers: concentration of gaseous ethylene oxide in containers

Because ethylene oxide (EO) gas is toxic to humans, restrictions have been imposed on its use for sterilization, specifying allowable levels of residual EO remaining in sterilized apparatus and materials. However, the aeration time that optimizes the removal of the remaining EO when a rigid sterilizing container is used for a vessel had not been identified. Therefore, polyvinyl chloride, which easily adsorbs EO, was placed in rigid sterilizing containers, and aeration was carried out after 1, 8, 12, 17, and 24 hours. After standard EO sterilization, the EO concentrations remaining in the air in the rigid containers were measured. The results indicate that a period of 17 hours of aeration is appropriate when a rigid sterilizing container is used.     

湘西地区蛇足石杉内生真菌的分离

采集不同生境的药用植物蛇足石杉,运用不同灭菌方法处理外植体,并用PDA平板培养基及孟加拉红培养基进行内生真菌的分离纯化.经过几种灭菌方法的摸索和比较研究,发现蛇足石杉外植体的灭菌十分困难(尤其是其茎部),难以在保持植物鲜活状态下达到一次彻底灭菌,有必要二次灭菌.通过二次灭菌分离得到的9株内生真菌中,来自蛇足石杉茎部的6株,来自叶片的3株.蛇足石杉的9株内生真菌在平板培养时生长极其缓慢,仅一株可在培养时产生孢子.     

Sterilization by means of Hydrogen Chloride: Influence of Process Parameters on Biocidal Activity

At ambient temperatures, hydrogen chloride is a strong bactericide. At a partial hydrogen chloride pressure of 30 mm Hg, the number of spore-bearing colony forming units present in straw dust particles of 0–32 μm was reduced by a factor-of more than 50 000 within 60 s. Naked spores of Bacillus subtilis were reduced in viability by a factor of 100 000 within only 10 s. Viability of vegetative cells of various kinds of bacteria was reduced by a factor of more than 10⁷ within 10 s. The method of administration of the gas influenced the sterilization and had to be adapted to the geometry of the surfaces to be sterilized. The smaller the dust particles, the better the sterilization, seemingly due to the lower degree of inhibition of diffusion of gas to the microorganisms enclosed in the particles. Increases in treatment time and concentration of hydrogen chloride enhanced the sterilizing effect to a lesser extent when large dust particles were involved. The partial water vapour pressure did not influence the sterilization between 0.3 and 6 mm Hg. An increase in temperature decreased the sterilizing effect.     

Automatic equipment for media sterilization

A device is described based on the principle of a simple analog computer which gives an exact determination of the moment at which the heat energy supply should be interrupted to attain a chosen sterilization effect. The temperature of the medium to be sterilized is measured and at temperatures above 100°C. the dependence of the thermal destruction coefficient of microbial spores on temperature is simulated. This variable is integrated with respect to time and the value of this integral at any given moment corresponds to the sterilization effect, at that moment. The device is also fitted with an extrapolator which evaluates, depending on the instantaneous temperature of the medium, the value of sterilization effect which will be produced during the cooling of the medium after the interruption of the heat, energy supply. The total sterilization effect, in the course of the cycle, is continuously and automatically evaluated as a sum of the integrated sterilization effect and of data supplied by the extrapolator. At the moment when this total sterilization effect attains the prescribed value, the device gives a signal for the interruption of the heat energy supply. The value of the sterilization effect is adjustable within broad limits and its evaluation is performed without substantial simplifying assumptions. By the use of this device an exact scale-up method for sterilizing media is achieved, yielding at the same time accurate reproducibility of media sterilization. An automatic control of the sterilization cycle is also possible by means of the device.     

Suppression and restoration of primordial germ cell marker gene expression in channel catfish,Ictalurus punctatus,using knockdown constructs regulated by copper transport protein gene promoters: Potential for reversible transgenic sterilization

Complementary DNA overexpression and short hairpin RNA interference approaches were evaluated for decreasing expression of primordial germ cell (PGC) marker genes and thereby sterilizing channel catfish, Ictalurus punctatus, by delivering knockdown constructs driven by a constitutive promoter from yeast and a copper transport protein gene into fish embryos by electroporation. Two PGC marker genes, nanos and dead end, were the target knockdown genes, and their expressions, along with that of an off-target gene, vasa, were evaluated temporally using real-time polymerase chain reaction. Copper sulfate was evaluated as a repressor compound. Some of the constructs knocked down PGC marker gene expression, and some of the constructs were partially repressed by application of 0.1-ppm copper sulfate. When the rate of sexual maturity was compared for three-year-old broodfish that had been exposed to the sterilizing constructs during embryologic development and controls that had not been exposed, several treatments had reduced sexual maturity for the exposed fish. Of two promoter systems evaluated, the one which had been designed to be less sensitive to copper generally was more effective at achieving sterilization and more responsive to repression. Knockdown constructs based on 3′ nanos short hairpin RNA interference appeared to result in the best repression and restoration of normal sexual maturity. We conclude that these copper-based systems exhibited good potential for repressible transgenic sterilization. Optimization of this system could allow environmentally safe application of transgenic technology and might be applicable to other applications for aquatic organisms.     

Maximized virulence in a sterilizing pathogen: the anther-smut fungus and its co-evolved hosts

Host sterilization is a common feature of sexually transmitted diseases (STDs). Because host reproductive failure may free up resources for pathogen reproduction and transmission, theory predicts that selection on sterilizing pathogens will favour maximum virulence (i.e. complete sterilization). We examined patterns of infection in sexually transmitted anther-smut fungi (Microbotryum) on four of their host species in the Caryophyllaceae. Using controlled fungal matings and experimental inoculations, we compared disease expression in inoculations ranging from host-specific pathogens to hybrids and cross-species treatments. Our data support the existence of host-specific sibling species within the genus Microbotryum based on a low infection rate from cross-inoculations and reduced fitness for hybrid pathogens. These patterns of host specificity and reproductive isolation, however, were not absolute. We did observe some successful cross-species and hybrid infections, but the expression of disease was frequently incomplete, including only partial host sterilization and the failed dehiscence of pathogen spores. The prevalence of these maladapted disease phenotypes may greatly inhibit the emergence of novel host pathogen combinations. Infections by hybrid pathogen genotypes were intermediate, in terms of both infection rate and the normality of disease symptoms, between host-specific and cross-inoculated pathogens. In addition, the frequency with which hybrid and cross-inoculated anther-smut pathogens were able to infect but not sterilize new hosts supports the prediction that sterilizing STDs are under selection to maximize virulence in natural populations.     

Fatal or Harmless: Extreme Bistability Induced by Sterilizing,Sexually Transmitted Pathogens

Models of sexually transmitted infections have become a fixture of mathematical epidemiology. A common attribute of all these models is treating reproduction and mating, and hence pathogen transmission, as uncoupled events. This is fine for humans, for example, where only a tiny fraction of sexual intercourses ends up with having a baby. But it can be a deficiency for animals in which mating and giving birth are tightly coupled, and mating thus mediates both reproduction and pathogen transmission. Here, we model dynamics of sterilizing, sexually transmitted infections in such animals, assuming structural consistency between the processes of reproduction and pathogen transmission. We show that highly sterilizing, sexually transmitted pathogens trigger bistability in the host population. In particular, the host population can end up in two extreme alternative states, disease-free persistence and pathogen-driven extinction, depending on its initial state. Given that sterilizing, sexually transmitted infections that affect animals are abundant, our results might implicate an effective pest control tactic that consists of releasing the corresponding pathogens, possibly after genetically enhancing their sterilization power.     

Terminal sterilization of medical devices using vaporized hydrogen peroxide: a review of current methods and emerging opportunities

Medical devices are an important and growing aspect of healthcare provision and are increasing in complexity to meet established and emerging patient needs. Terminal sterilization plays a vital role in the provision of safe medical devices. While terminal sterilization technologies for medical devices include multiple radiation options, ethylene oxide remains the predominant nonthermal gaseous option, sterilizing c. 50% of all manufactured devices. Vaporized hydrogen peroxide (abbreviated VH2O2 by the International Organization for Standardization) is currently deployed for clinical sterilization applications, where its performance characteristics appear aligned to requirements, constituting a viable alternative low-temperature process for terminal processing of medical devices. However, VH2O2 has operational limitations that create technical challenges for industrial-scale adoption. This timely review provides a succinct overview of VH2O2 in gaseous sterilization and addresses its applicability for terminal sterilization of medical devices. It also describes underappreciated factors such as the occurrence of nonlinear microbial inactivation kinetic plots that may dictate a need to develop a new standard approach to validate VH2O2 for terminal sterilization of medical devices.     

Pupal X-ray irradiation influences protein expression in adults of the oriental fruit fly,Bactrocera dorsalis

The oriental fruit fly, Bactrocera dorsalis, is a pest of fruit in the Asia–Pacific region and also, due to quarantine restrictions, a threat to California fruit production. Area-wide suppression of B. dorsalis integrated several approaches including the sterile insect technique (SIT). SIT involves exposing juveniles to gamma radiation and releasing sterile males in substantial numbers, where they successfully compete for wild females. The resulting infertile eggs lead to reduction of the pest populations. Although these protocols are well documented, arising issues about the international transport and distribution of radioactive products is creating difficulties in use of radioactive sources for sterilizing radiation. This led to a shift toward use of X-ray irradiation, which also sterilizes male and female insects. However, use of X-ray technologies is in its infancy and there is virtually no information on the effects of irradiation, other than sterilization, at the physiological and molecular levels of fruit fly biology. We posed the hypothesis that sterilizing male oriental fruit flies via radiation treatment also influences protein expression in the flies. We found that exposing pupae to X-ray irradiation impacted expression of 26 proteins in adult females and 31 proteins in adult males. Seven proteins (glyceraldehyde-3-phosphate dehydrogenase, fructose-bisphosphate aldolase, larval cuticle protein 2, sarcoplasmic calcium-binding protein alpha-B and A chains, general odorant-binding protein 99b, polyubiquitin, and protein disulfide-isomerase) were impacted in both sexes. Some of the proteins act in central energy-generating and in pheromone-signal processing pathways; we infer that males sterilized by X-ray irradiation may be enfeebled in their ability to compete with wild males for females in nature.     

THE PORPHYRIN REQUIREMENTS OF HAEMOPHILUS INFLUENZAE AND SOME FUNCTIONS OF THE VINYL AND PROPIONIC ACID SIDE CHAINS OF HEME

1. Iron protoporphyrin IX was required for the growth of H. influenzae. It could be replaced by protoporphyrin IX. When grown on protoporphyrin evidence was obtained for the presence of Fe porphyrin in the organism. It was concluded that the organism could insert iron into the protoporphyrin ring. 2. In the smooth strains, other porphyrins containing no iron such as deutero-, hemato-, meso-, and coproporphyrins could not replace protoporphyrin for growth. Since protoporphyrin has two vinyl groups which other porphyrins lack, it was concluded that the two vinyl groups were essential for growth. 3. When porphyrins lacking vinyl groups were converted chemically into iron porphyrins and then supplied to the organisms it was found that these iron porphyrins supported growth. It was concluded that the "smooth" organisms were able to insert iron only into the porphyrin containing the vinyl groups; i.e., protoporphyrin. One function of the vinyl groups then was to permit iron to be inserted biologically into the porphyrin ring. 4. An anomalous behavior in the rough Turner strain was observed and discussed. This organism was able to insert iron into mesoporphyrin at low concentrations but was inhibited by this compound at higher concentrations. In all other reactions with the porphyrins this rough strain behaved in the same was as did the smooth strains. 5. All strains which were grown on iron porphyrins lacking vinyl groups could not reduce nitrate to nitrite. When grown on protoporphyrin or Fe protoporphyrin reduction of nitrate occurred. It was concluded that the nitrate-reducing mechanism required the presence of the vinyl groups either for its formation or function. 6. The porphyrins lacking iron and lacking vinyl groups inhibited the growth of H. influenzae on Fe protoporphyrin. The inhibition between a porphyrin and Fe protoporphyrin was a competitive one. It was suggested that the porphyrin inhibited the growth-promoting properties of Fe protoporphyrin by attaching on to a particular apoprotein, thus preventing the formation of a heme catalyst. Likewise, competition between two growth-promoting Fe porphyrins for apoenzymes could be shown to occur. 7. Protoporphyrin and Fe protoporphyrin supported growth. When their propionic acid side chains were esterified they no longer supported growth. It was suggested that the esterified carboxyl groups could not attach to the specific apoproteins to form the heme enzymes and so could not act to support growth. For the same reason the inhibitory action of porphyrins lacking vinyl groups could be prevented by esterifying their propionic acid groups.