Inactivation of avirulent Yersinia pestis in Butterfield's phosphate buffer and frankfurters by UVC (254 nm) and gamma radiation.

PubMed

Sommers, Christopher H; Cooke, Peter H

2009-04-01

Yersinia pestis is the causative agent of plague. Although rare, pharyngeal plague in humans has been associated with consumption or handling of meat prepared from infected animals. The risks of contracting plague from consumption of deliberately contaminated food are currently unknown. Gamma radiation is a penetrating form of electromagnetic radiation, and UVC radiation is used for decontamination of liquids or food surfaces. Gamma radiation D10-values (the radiation dose needed to inactivate 1 log unit pathogen) were 0.23 (+/-0.01) and 0.31 (+/-0.03) kGy for avirulent Y. pestis inoculated into Butterfield's phosphate buffer and onto frankfurter surfaces, respectively, at 0 degree C. A UVC radiation dose of 0.25 J/cm2 inactivated avirulent Y. pestis suspended in Butterfield's phosphate buffer. UVC radiation doses of 0.5 to 4.0 J/cm2 inactivated 0.97 to 1.20 log units of the Y. pestis surface inoculated onto frankfurters. A low gamma radiation dose of 1.6 kGy could provide a 5-log reduction and a UVC radiation dose of 1 to 4 J/cm2 would provide a 1-log reduction of Y. pestis surface inoculated onto frankfurters. Y. pestis was capable of growth on frankfurters during refrigerated storage (10 degrees C). Gamma radiation of frankfurters inhibited the growth of Y. pestis during refrigerated storage, and UVC radiation delayed the growth of Y. pestis.

Inactivation of rabies diagnostic reagents by gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamble, W.C.; Chappell, W.A.; George, E.H.

1980-11-01

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

The radiation hypersensitivity of cells at mitosis.

PubMed

Stobbe, C C; Park, S J; Chapman, J D

2002-12-01

Mitotic cells are hypersensitive to ionizing radiation, exhibiting single-hit inactivation coefficients near to those of repair deficient cell lines and lymphocytes. To elucidate possible mechanisms for this hypersensitivity, the kinetics of oxygen radiosensitization, the proportion of indirect effect by OH radicals and the kinetics of radiation-induced DNA strand breakage in the chromatin of mitotic cells were investigated. Synchronized populations of >90% mitotic HT-29 cells were obtained by the mitotic shake-off method. Cells were irradiated at < or =4 degrees C with (137)Cs gamma-rays. Cellular oxygen concentration was varied by gassing cell suspensions prior to and during irradiation with mixtures of pure N(2) that contained 5% CO(2) and measured quantities of O(2). The indirect effect of OH radicals was investigated with the radical scavenger, DMSO. DNA strand breakage was measured by the comet assay. Mitotic HT-29 cell inactivation is well described by a single-hit inactivation coefficient (alpha) of 1.14 +/- 0.06 Gy(-1). The oxygen enhancement ratio of mitotic cells (at 10% survival) was found to be approximately 2.0, significantly lower than the value of 2.8 measured for interphase (asynchronous) cells. More than 60% of mitotic cell killing was eliminated when the media contained 2 M DMSO, indicating that indirect effect is as important in the killing of mitotic cells as it is for interphase cells. The chromatin in mitotic cells was found to be ~2.8 times more sensitive to radiation-induced DNA single-strand breakage than the chromatin of interphase cells. The alpha-inactivation coefficient of mitotic HT-29 cells was ~30 times larger than that of interphase cells. Mitotic cell chromatin appears to contain intrinsic DNA breaks that are not lethal. In addition, chromatin in mitotic cells was found to be more susceptible to radiation-induced DNA strand-breakage than the dispersed chromatin of interphase cells. How the enhanced production of these simple DNA lesions (that are usually reparable) translates into the lethal (non-reparable) events associated with alpha-inactivation is not known. The compaction/dispersion status of DNA throughout the cell cycle appears to be an important factor for determining intrinsic cell radiosensitivity and might be manipulated for radiotherapeutic advantage.

Pathogens Inactivated by Low-Energy-Electron Irradiation Maintain Antigenic Properties and Induce Protective Immune Responses

PubMed Central

Fertey, Jasmin; Bayer, Lea; Grunwald, Thomas; Pohl, Alexandra; Beckmann, Jana; Gotzmann, Gaby; Casado, Javier Portillo; Schönfelder, Jessy; Rögner, Frank-Holm; Wetzel, Christiane; Thoma, Martin; Bailer, Susanne M.; Hiller, Ekkehard; Rupp, Steffen; Ulbert, Sebastian

2016-01-01

Inactivated vaccines are commonly produced by incubating pathogens with chemicals such as formaldehyde or β-propiolactone. This is a time-consuming process, the inactivation efficiency displays high variability and extensive downstream procedures are often required. Moreover, application of chemicals alters the antigenic components of the viruses or bacteria, resulting in reduced antibody specificity and therefore stimulation of a less effective immune response. An alternative method for inactivation of pathogens is ionizing radiation. It acts very fast and predominantly damages nucleic acids, conserving most of the antigenic structures. However, currently used irradiation technologies (mostly gamma-rays and high energy electrons) require large and complex shielding constructions to protect the environment from radioactivity or X-rays generated during the process. This excludes them from direct integration into biological production facilities. Here, low-energy electron irradiation (LEEI) is presented as an alternative inactivation method for pathogens in liquid solutions. LEEI can be used in normal laboratories, including good manufacturing practice (GMP)- or high biosafety level (BSL)-environments, as only minor shielding is necessary. We show that LEEI efficiently inactivates different viruses (influenza A (H3N8), porcine reproductive and respiratory syndrome virus (PRRSV), equine herpesvirus 1 (EHV-1)) and bacteria (Escherichia coli) and maintains their antigenicity. Moreover, LEEI-inactivated influenza A viruses elicit protective immune responses in animals, as analyzed by virus neutralization assays and viral load determination upon challenge. These results have implications for novel ways of developing and manufacturing inactivated vaccines with improved efficacy. PMID:27886076

Radiation-Induced Leukemia at Doses Relevant to Radiation Therapy: Modeling Mechanisms and Estimating Risks

NASA Technical Reports Server (NTRS)

Shuryak, Igor; Sachs, Rainer K.; Hlatky, Lynn; Mark P. Little; Hahnfeldt, Philip; Brenner, David J.

2006-01-01

Because many cancer patients are diagnosed earlier and live longer than in the past, second cancers induced by radiation therapy have become a clinically significant issue. An earlier biologically based model that was designed to estimate risks of high-dose radiation induced solid cancers included initiation of stem cells to a premalignant state, inactivation of stem cells at high radiation doses, and proliferation of stem cells during cellular repopulation after inactivation. This earlier model predicted the risks of solid tumors induced by radiation therapy but overestimated the corresponding leukemia risks. Methods: To extend the model to radiation-induced leukemias, we analyzed in addition to cellular initiation, inactivation, and proliferation a repopulation mechanism specific to the hematopoietic system: long-range migration through the blood stream of hematopoietic stem cells (HSCs) from distant locations. Parameters for the model were derived from HSC biologic data in the literature and from leukemia risks among atomic bomb survivors v^ ho were subjected to much lower radiation doses. Results: Proliferating HSCs that migrate from sites distant from the high-dose region include few preleukemic HSCs, thus decreasing the high-dose leukemia risk. The extended model for leukemia provides risk estimates that are consistent with epidemiologic data for leukemia risk associated with radiation therapy over a wide dose range. For example, when applied to an earlier case-control study of 110000 women undergoing radiotherapy for uterine cancer, the model predicted an excess relative risk (ERR) of 1.9 for leukemia among women who received a large inhomogeneous fractionated external beam dose to the bone marrow (mean = 14.9 Gy), consistent with the measured ERR (2.0, 95% confidence interval [CI] = 0.2 to 6.4; from 3.6 cases expected and 11 cases observed). As a corresponding example for brachytherapy, the predicted ERR of 0.80 among women who received an inhomogeneous low-dose-rate dose to the bone marrow (mean = 2.5 Gy) was consistent with the measured ERR (0.62, 95% Cl =-0.2 to 1.9). Conclusions: An extended, biologically based model for leukemia that includes HSC initiation, inactivation, proliferation, and, uniquely for leukemia, long-range HSC migration predicts, %Kith reasonable accuracy, risks for radiationinduced leukemia associated with exposure to therapeutic doses of radiation.

Inactivation of Escherichia coli O157:H7 and Salmonella by gamma irradiation of alfalfa seed intended for production of food sprouts.

PubMed

Thayer, Donald W; Rajkowski, Kathleen T; Boyd, Glenn; Cooke, Peter H; Soroka, Douglas S

2003-02-01

Inonizing irradiation was determined to be a suitable method for the inactivation of Salmonella and Escherichia coli O157:H7 on alfalfa seed to be used in the production of food sprouts. The radiation D (dose resulting in a 90% reduction of viable CFU) values for the inactivation of Salmonella and E. coli O157:H7 on alfalfa seeds were higher than the D-values for their inactivation on meat or poultry. The average D-value for the inactivation of Salmonella on alfalfa seeds was 0.97 +/- 0.03 kGy; the D-values for cocktails of meat isolates and for vegetable-associated isolates were not significantly different. The D-values for nonoutbreak and outbreak isolates of E. coli O157:H7 on alfalfa seeds were 0.55 +/- 0.01 and 0.60 +/- 0.01 kGy, respectively. It was determined that the relatively high D-values were not due to the low moisture content or the low water activity of the seed. The D-values for Salmonella on alfalfa seeds from two different sources did not differ significantly, even though there were significant differences in seed size and water activity. The increased moisture content of the seed after artificial inoculation did not significantly alter the D-value for the inactivation of Salmonella. The results of this study demonstrate that 3.3- and 2-log inactivations can be achieved with a 2-kGy dose of ionizing radiation, which will permit satisfactory commercial yields of sprouts from alfalfa seed contaminated with E. coli O157:H7 and Salmonella, respectively.

Variations in the radiation sensitivity of foodborne pathogens associated with complex ready-to-eat food products

NASA Astrophysics Data System (ADS)

Sommers, Christopher H.; Boyd, Glenn

2006-07-01

Foodborne illness outbreaks and product recalls are occasionally associated with ready-to-eat (RTE) sandwiches and other "heat and eat" multi-component RTE products. Ionizing radiation can inactivate foodborne pathogens on meat and poultry, fruits and vegetables, seafood, and RTE meat products. However, less data are available on the ability of low-dose ionizing radiation, doses under 5 kGy typically used for pasteurization purposes, to inactivate pathogenic bacteria on complex multi-component food products. In this study, the efficacy of ionizing radiation to inactivate Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Yersinia enterocolitica on RTE foods including a "frankfurter on a roll", a "beef cheeseburger on a bun" and a "vegetarian cheeseburger on a bun" was investigated. The average D-10 values, the radiation dose needed to inactivate 1 log 10 of pathogen, by bacterium species, were 0.61, 0.54, 0.47, 0.36 and 0.15 kGy for Salmonella spp., S. aureus, L. monocytogenes, E. coli O157:H7, and Y. enterocolitica, respectively when inoculated onto the three product types. These results indicate that irradiation may be an effective means for inactivating common foodborne pathogens including Salmonella spp, S. aureus, L. monocytogenes, E. coli O157:H7 and Y. enterocolitica in complex RTE food products such as 'heat and eat" sandwich products.

Physicochemical inactivation of Lassa, Ebola, and Marburg viruses and effect on clinical laboratory analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, S.W.; McCormick, J.B.

1984-09-01

Clinical specimens from patients infected with Lassa, Ebola, or Marburg virus may present a serious biohazard to laboratory workers. The authors have examined the effects of heat, alteration of pH, and gamma radiation on these viruses in human blood and on the electrolytes, enzymes, and coagulation factors measured in laboratory tests that are important in the care of an infected patient. Heating serum at 60 degrees C for 1 h reduced high titers of these viruses to noninfectious levels without altering the serum levels of glucose, blood urea nitrogen, and electrolytes. Dilution of blood in 3% acetic acid, diluent formore » a leukocyte count, inactivated all of these viruses. All of the methods tested for viral inactivation markedly altered certain serum proteins, making these methods unsuitable for samples that are to be tested for certain enzyme levels and coagulation factors.« less

Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Zhen; Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081; Gan, Ye-Hua, E-mail: kqyehuagan@bjmu.edu.cn

2015-05-01

Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocationmore » and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.« less

Rapid disinfection of E-Coliform contaminated water using WO3 semiconductor catalyst by laser-induced photo-catalytic process.

PubMed

Gondal, Mohammed A; Khalil, Amjad

2008-04-01

Laser-induced photo-catalysis process using WO(3) semiconductor catalyst was applied for the study of disinfection effectiveness of E-coliform-contaminated water. For this purpose, wastewater polluted with E-coliform bacteria was exposed to 355 nm UV radiations generated by third harmonic of Nd: YAG laser in special glass cell with and without WO(3) catalyst. E-Coliform quantification was performed by direct plating method to obtain the efficiency of each disinfection treatment. The dependence of disinfection process on laser irradiation energy, amount of catalyst and duration of laser irradiation was also investigated. The disinfection with WO(3) was quite efficient inactivating E-coliforms. For inactivation of E-coliforms, less than 8 minutes' laser irradiation was required, so that, the treated water complies with the microbial standards for drinking water. This study opens the possibility of application of this simple method in rural areas of developing countries using solar radiation.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components. [bibliography

NASA Technical Reports Server (NTRS)

Reyes, A. L.; Campbell, J. E.

1976-01-01

Almost 600 articles and books published since 1960 about microbial and viral inactivation are listed. This bibliography is presented to facilitate literature reviews on chemical, heat, and radiation inactivation of microorganisms and viral particles.

Solar Radiation Disinfection of Drinking Water at Temperate Latitudes: Inactivation rates for an optimized reactor configuration

EPA Science Inventory

Solar radiation-driven inactivation of bacteria, virus and protozoan pathogen models was quantified in simulated drinking water at a temperate latitude (34°S). The water was seeded with Enterococcus faecalis, Clostridium sporogenes spores, and P22 bacteriophage, each at ca 1 x 10...

Electrochemically assisted photocatalysis: Highly efficient treatment using thermal titanium oxides doped and non-doped electrodes for water disinfection.

PubMed

Dos Santos, Andreia Betina Kreuser; Claro, Elis Marina Turini; Montagnolli, Renato Nallin; Cruz, Jaqueline Matos; Lopes, Paulo Renato Matos; Bidoia, Ederio Dino

2017-12-15

Electrochemically assisted photocatalysis (by electronic drainage) is a highly promising method for disinfection of water. In this research, the efficiency of photolytic oxidation using UV-A radiation and electrochemically assisted photocatalysis (with electric potential of 1.5 V) was studied by using electrodes prepared by thermal treatment and doped with silver, for inactivation of Escherichia coli and Staphylococcus aureus. The Chick-Watson microorganism inactivation model was applied and the electrical energy consumption of the process was calculated. It was observed no significant inactivation of microorganisms when UV-A light or electric potential were applied separately. However, the electrochemically assisted photocatalytic process, with Ag-doped electrode completely inactivated the microbial population after 10 (E. coli) and 60 min (S. aureus). The best performing non-doped electrodes achieved 52.74% (E. coli) and 44.09% (S. aureus) inactivation rates after 60 min. Thus, electrochemically assisted photocatalytic activity was not only effective for the inactivation of microorganisms, but also notably low on electrical energy consumption during the treatment due to small current and low electric potential applied. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanisms of the effect of VUV radiation on the microfungi

NASA Astrophysics Data System (ADS)

Zvereva, Galina; Kirtsideli, Irina; Machs, Eduard; Vangonen, Albert

2018-04-01

The mechanisms of the effect of vacuum ultraviolet (VUV) radiation (λ = 172 nm) on various types of microfungi spores were investigated. It is found that there are several parallel direct and indirect mechanisms, which lead to spores inactivation, including destruction of the cell wall and DNA by means of direct absorption of VUV radiation and by VUV photolysis reactive products. IR transmission spectra indicate the etching of the spore cell wall material with the predominant degradation of the polysaccharides. Electrophoresis of irradiated spores DNA shows heavy (about 20 000 pairs of nucleotides) and light fragments appearance. Experiments using an antioxidant (iodine) indicate the participation of reactive radicals in inactivation, which provide not less than 10% of inactivated cells

Electromagnetic energy and food processing.

PubMed

Mudgett, R

1988-01-01

The use of electromagnetic energy in food processing is reviewed with respect to food safety, nutritional quality, and organoleptic quality. The effects of nonionizing radiation sources such as microwave and radio-frequency energy and ionizing radiation sources, e.g. radioactive cobalt-60 and caesium-137, on the inactivation of microbes and nutrients are compared with those of conventional heating processes both in terms of their kinetic behavior and their mechanisms of interaction with foods. The kinetics of microwave and conventional thermal inactivation are considered for a generalized nth-order model based on time and temperature conditions. However, thermal inactivation effects are often modeled by 1st-order kinetics. Microbial and nutrient inactivation by ionizing sources are considered for a 1st-order model based on radiation dose. Both thermal and radiation resistance concepts are reviewed and some typical values of radiation resistance are given for sensitive vegetative bacterial cells, yeasts, and molds and for resistant bacterial spores and viruses. Nonionizing microwave energy sources are increasingly used in home and industrial food processing and are well-accepted by the American public. But, despite recent Food and Drug Administration approval of low and intermediate ionizing radiation dose levels for grains and other plants products and the fact that irradiated foods are sold in more than 20 countries of the world, public fears in the U.S. about nuclear energy may limit the role of ionizing radiation in food processing and preservation and may also limit the use of nuclear fuels as an alternate source of electrical energy.

Analysis of antigen conservation and inactivation of gamma-irradiated avian influenza virus subtype H9N2.

PubMed

Salehi, Bahareh; Motamedi-Sedeh, Farahnaz; Madadgar, Omid; Khalili, Iraj; Ghalyan Chi Langroudi, Arash; Unger, Hermann; Wijewardana, Viskam

2018-06-01

Avian influenza (AI) A subtype H9N2 virus belongs to Orthomyxoviridae family and causes low-pathogenic disease AI. The use of gamma-irradiated viral antigens has been developed in the production of effective vaccines. In this research, LPAIV H9N2 strain, A/Chicken/IRN/Ghazvin/2001, was multiplied on SPF eggs and irradiated by a Nordian gamma cell instrument. Irradiated and non-irradiated AI virus (AIV) samples were titrated by EID50 method and hemagglutinin (HA) antigen was analyzed by HA test as the WHO pattern method. Infectivity of irradiated virus was determined by egg inoculation method during four blind cultures. The results showed that after increasing the dose of gamma radiation, virus titer gradually decreased. D 10 value and optimum dose for complete virus inactivation were calculated by dose/response curve, 3.36 and 29.52 kGy, respectively. In addition, HA antigenicity of gamma-irradiated virus samples from 0 to 30 kGy was not changed. The results of safety test for gamma-irradiated AIV samples showed complete inactivation with gamma ray doses 30 and 35 kGy, without any multiplication on eggs after four blind cultures. According to the results of HA antigen assay and safety test, the gamma-irradiated and complete inactivated AIV subtype H9N2 is a good candidate as an inactivated immunogenic agent for poultry vaccination.

Effects of heavy ions on inactivation and DNA double strand breaks in Deinococcus radiodurans R1.

PubMed

Zimmermann, H; Schafer, M; Schmitz, C; Bucker, H

1994-10-01

Inactivation and double strand break (dsb) induction after heavy ion irradiation were studied in stationary phase cells of the highly radiation resistant bacterium Deinococcus radiodurans R1. There is evidence that the radiation sensitivity of this bacterium is nearly independent on energy in the range of up to 15 MeV/u for lighter ions (Ar). The responses to dsb induction for charged particles show direct relationship between increasing radiation dose and residual intact DNA.

Determination of the functional size of oxytocin receptors in plasma membranes from mammary gland and uterine myometrium of the rat by radiation inactivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soloff, M.S.; Beauregard, G.; Potier, M.

1988-05-01

Gel filtration of detergent-solubilized oxytocin (OT) receptors in plasma membrane fractions from both regressed mammary gland and labor myometrium of the rat, showed that specific (/sup 3/H)OT binding was associated with a heterogeneously sized population of macromolecules. As radiation inactivation is the only method available to measure the apparent molecular weights of membrane proteins in situ, we used this approach to define the functional sizes of OT receptors. The results indicate that both mammary and myometrial receptors are uniform in size and of similar molecular mass. Mammary and myometrial receptors were estimated to be 57.5 +/- 3.8 (SD) and 58.8more » +/- 1.6 kilodaltons, respectively. Knowledge of the functional size of OT receptors will be useful in studies involving the purification and characterization of the receptor and associated membrane components.« less

Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

PubMed Central

Felker, Daniel L.; Burggraf, Larry W.

2014-01-01

Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating. PMID:24375142

Regression model for estimating inactivation of microbial aerosols by solar radiation.

PubMed

Ben-David, Avishai; Sagripanti, Jose-Luis

2013-01-01

The inactivation of pathogenic aerosols by solar radiation is relevant to public health and biodefense. We investigated whether a relatively simple method to calculate solar diffuse and total irradiances could be developed and used in environmental photobiology estimations instead of complex atmospheric radiative transfer computer programs. The second-order regression model that we developed reproduced 13 radiation quantities calculated for equinoxes and solstices at 35(°) latitude with a computer-intensive and rather complex atmospheric radiative transfer program (MODTRAN) with a mean error <6% (2% for most radiation quantities). Extending the application of the regression model from a reference latitude and date (chosen as 35° latitude for 21 March) to different latitudes and days of the year was accomplished with variable success: usually with a mean error <15% (but as high as 150% for some combination of latitudes and days of year). This accuracy of the methodology proposed here compares favorably to photobiological experiments where the microbial survival is usually measured with an accuracy no better than ±0.5 log10 units. The approach and equations presented in this study should assist in estimating the maximum time during which microbial pathogens remain infectious after accidental or intentional aerosolization in open environments. © Published 2013. This article is a U.S. Government work and is in the public domain in the USA. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Impact of UVA pre-radiation on UVC disinfection performance: Inactivation, repair and mechanism study.

PubMed

Xiao, Y; Chu, X N; He, M; Liu, X C; Hu, J Y

2018-05-15

Ultraviolet (UV) light emission diode (LED), which is mercury free and theoretically more energy efficient, has now become an alternative to conventional UV lamps in water disinfection industry. In this research, the disinfection performance of a novel sequential process, UVA 365nm LED followed by UVC 265nm LED (UVA-UVC), was evaluated. The results revealed that the responses of different bacterial strains to UVA-UVC varied. Coupled with appropriate dosages of UVC, a 20 min UVA pre-radiation provided higher inactivations (log inactivation) of E. coli ATCC 11229, 15597 and 700891 by 1.2, 1.4 and 1.2 times, respectively than the sum of inactivations by UVA alone and UVC alone. On the contrary, the inactivation of E. coli ATCC 25922, the most UVC sensitive strain, decreased from 3 log to 1.8 log after UVA pre-radiation. A 30 min UVA pre-radiation did not affect the photo repair capacity of the four strains (n = 23, p > 0.1), but their dark repair ability was significantly inhibited (n = 14, p < 0.05). Mechanism study was conducted for two representative strains, E. coli ATCC 15597 and 25922 to understand the observed effect. The hypothesis that UVA pre-radiation promoted the yield of reactive oxygen species (ROS) was rejected. ELISA results indicated that 18% more cyclobutane pyrimidine dimers (CPD) were formed in E. coli ATCC 15597 with UVA pre-radiation (n = 3, p < 0.01), however, the CPD levels of E. coli ATCC 25922 was the same with or without UVA pre-radiation (n = 3, p > 0.01). Considering the results of both dark repair and CPD formation, it was concluded that the increased UV sensitivity of E. coli 15597 was originated from the increased CPD. For E. coli ATCC 25922, the enhanced UV resistance was attributed to the strain's adoption of a survival strategy, translesion DNA synthesis (TLS), when triggered by UVA pre-radiation. The study on UmuD protein, which is a key protein during TLS, confirmed this hypothesis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mechanisms of poliovirus inactivation by the direct and indirect effects of ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, R.L.

1980-08-01

This study was designed to measure the effects of ionizing radiation on poliovirus particles when given under conditions where either direct (in broth) or indirect (in water) effects were predominant. Under direct conditions, inactivation of poliovirus was found to be due primarily to RNA damage, although capsid damage could account for about one-third of the viral inactivation. RNA damage did not appear to be due to strand breakage and therefore was probably caused primarily by base damage or crosslink formation. Capsid damage under direct irradiation conditions did not result in significant alterations of either the sedimentation coefficients or the isoelectricmore » points of the poliovirus particles or detectable modification of the sizes of the viral proteins. It did, however, cause loss of availability to bind to host cells. Under indirect conditions no more than 25% of viral inactivation appeared to be due to RNA damage. However, the sedimentation coefficients and isoelectric points of the viral particles were greatly altered, and their abilities to bind to cells were lost at about three-fourths the rate of loss of infectivity. Capsid damage in this case did result in changes in the sizes of capsid proteins. Therefore, the majority of the radiation inactivation under indirect conditions appeared to be due to protein damage.« less

Inactivation of poliovirus in wastewater sludge with radiation and thermoradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, R.L.

1977-05-01

The effect of sludge on the rate of viral inactivation by radiation and thermoradiation was determined. The virus used for the experiments was the poliovirus type 1 strain CHAT, which was grown in HeLa cells. Radiation, heat, and thermoradiation treatments were carried out in a chamber specifically designed to permit rapid heating and cooling of the samples at the beginning and completion of treatment, respectively. The treated samples were then assayed for plaque-forming units on HeLa cells after sonication in 0.1% sodium dodecylsulfate (SDS). For the radiation treatment virus was diluted 10-fold into PBS containing new sludge, irradiated at 20/supmore » 0/C with /sup 137/Cs at a dose rate of 30 krads/min, and assayed for infectious virus. The results show that raw sludge is protective of poliovirus against ionizing radiation but that small concentrations of sludge are nearly as protective as large concentrations. When heat and radiation are given simultaneously, however, the amount of protection afforded by sludge is less than the additive effects of the individual treatments. This result is especially evident at low concentrations of sludge. It appears, therefore, that thermoradiation treatment may be an effective way of inactivation viruses in waters containing low concentrations of suspended solids. (FMM)« less

A high-performance doped photocatalysts for inactivation of total coliforms in superficial waters using different sources of radiation.

PubMed

Claro, Elis Marina Turini; Bidoia, Ederio Dino; de Moraes, Peterson Bueno

2016-07-15

Photocatalytic water treatment has a currently elevated electricity demand and maintenance costs, but the photocatalytic water treatment may also assist in overcoming the limitations and drawbacks of conventional water treatment processes. Among the Advanced Oxidation Processes, heterogeneous photocatalysis is one of the most widely and efficiently used processes to degrade and/or remove a wide range of polluting compounds. The goal of this work was to find out a highly efficient photocatalytic disinfection process in superficial water with different doped photocatalysts and using three sources of radiation: mercury vapor lamp, solar simulator and UV-A LED. Three doped photocatalysts were prepared, SiZnO, NSiZnO and FNSiZnO. The inactivation efficiency of each synthesized photocatalysts was compared to a TiO2 P25 (Degussa(®)) 0.5 g L(-1) control. Photolysis inactivation efficiency was 85% with UV-A LED, which is considered very high, demanding low electricity consumption in the process, whereas mercury vapor lamp and solar simulator yielded 19% and 13% inactivation efficiency, respectively. The best conditions were found with photocatalysts SiZnO, FNSiZnO and NSiZnO irradiated with UV-A LED, where efficiency exceeded 95% that matched inactivation of coliforms using the same irradiation and photocatalyst TiO2. All photocatalysts showed photocatalytic activity with all three radiation sources able to inactivate total coliforms from river water. The use of UV-A LED as the light source without photocatalyst is very promising, allowing the creation of cost-effective and highly efficient water treatment plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultraviolet irradiation: An effective inactivation method of Aspergillus spp. in water for the control of waterborne nosocomial aspergillosis.

PubMed

Nourmoradi, H; Nikaeen, M; Stensvold, C R; Mirhendi, H

2012-11-15

Invasive aspergillosis is the second most common cause of nosocomial fungal infections and occurring mainly by Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger. There is evidence that nosocomial aspergillosis may be waterborne. This study was conducted to evaluate the ultraviolet (UV) irradiation efficiency in terms of inactivating the most important Aspergillus species in water since these are potential sources for nosocomial aspergillosis. A continuous flow UV reactor which could be used as a point-of-use (POU) system was used to survey Aspergillus inactivation by UV irradiation. The inactivation efficiency of UV fluence (4.15-25 mJ/cm(2)) was measured by determination of fungal density in water before and after radiation. Because turbidity and iron concentration are two major water quality factors impacting UV disinfection effectiveness, the potential influence of these factors on UV inactivation of Aspergillus spp. was also measured. The 4 log inactivation for A. fumigatus, A. niger and A. flavus at a density of 1000 cfu/ml was achieved at UV fluences of 12.45 mJ/cm(2), 16.6 mJ/cm(2) and 20.75 mJ/cm(2), respectively. The inactivation efficiency for lower density (100 cfu/ml) was the same as for the higher density except for A. flavus. The removal efficiency of Aspergillus spp. was decreased by increasing the turbidity and iron concentration. UV disinfection could effectively inactivate Aspergillus spores from water and eliminate potential exposure of high-risk patients to fungal aerosols by installation of POU UV systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Inactivation of murine norovirus-1 in the edible seaweeds Capsosiphon fulvescens and Hizikia fusiforme using gamma radiation.

PubMed

Park, Shin Young; Kang, Sujin; Ha, Sang-Do

2016-06-01

This study investigated the effects of gamma radiation (3-10 kGy) upon the inactivation of murine norovirus-1 (MNV-1), a human norovirus (NoV) surrogate. The edible green and brown algae, fulvescens (Capsosiphon fulvescens) and fusiforme (Hizikia fusiforme), respectively, were experimentally contaminated with 5-6 log10 plaque forming units (PFU)/ml MNV-1. The titer of MNV-1 significantly decreased (P < 0.05) as the dose of gamma radiation increased. MNV-1 titer decreased to 1.16-2.46 log10 PFU/ml in fulvescens and 0.37-2.21 log10 PFU/ml in fusiforme following irradiation. However, all Hunters ('L', 'a' and 'b') and sensory qualities (appearance, color, flavor, texture and overall acceptability) were not significantly (P > 0.05) different in both algae following gamma radiation. The Weibull model was used to generate non-linear survival curves and to calculate Gd values for 1, 2, and 3 log10 reductions of MNV-1 in fulvescens (R(2) = 0.992) and fusiforme (R(2) = 0.988). A Gd value of 1 (90% reduction) corresponded to 2.89 and 3.93 kGy in fulvescens and fusiforme, respectively. A Gd value of 2 (99% reduction) corresponded to 7.75 and 9.02 kGy in fulvescens and fusiforme, respectively, while a Gd value of 3 (99.9% reduction) in fulvescens and fusiforme corresponded with 13.83 and 14.93 kGy of gamma radiation, respectively. A combination of gamma radiation at medium doses and other treatments could be used to inactivate ≥ 3 log10 PFU/ml NoV in seaweed. The inactivation kinetics due to gamma radiation against NoV in these algae might provide basic information for use in seaweed processing and distribution. Copyright © 2015. Published by Elsevier Ltd.

LOW PRESSURE ULTRAVIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS

EPA Science Inventory

This research was initiated to confirm and expand the current database for the inactivation of Giardia spp. using ultraviolet (UV) radiation. Initially, previous research that used in vitro excystation as the indicator for UV effectiveness was confirmed. Later, the in vitro excys...

Microwave-Irradiation-Assisted HVAC Filtration for Inactivation of Viral Aerosols (Postprint)

DTIC Science & Technology

2012-02-01

Baggiani, A. and Senesi, S. (2004). Effect of Microwave Radiation on Bacillus subtilis Spores . J. Appl. Microbiol. 97: 1220–1227. Damit, B., Lee, C.N...AFRL-RX-TY-TP-2012-0020 MICROWAVE-IRRADIATION-ASSISTED HVAC FILTRATION FOR INACTIVATION OF VIRAL AEROSOLS POSTPRINT Myung-Heui Woo and...12-APR-2011 -- 11-DEC-2011 Microwave Irradiation-Assisted HVAC Filtration for Inactivation of Viral Aerosols (POSTPRINT) FA8650-06-C-5913 0602102F

Inactivation pathogenic microorganisms in water by laser methods

NASA Astrophysics Data System (ADS)

Iakovlev, Alexey; Grishkanich, Aleksandr; Kascheev, Sergey; Ruzankina, Julia; Afanasyev, Mikhail; Hafizov, Nail

2017-02-01

As a result of the research the following methods have been proposed for controlling harmful microorganisms: sterilization of water by laser radiation at wavelengths of 425 nm, 355 nm and 308 nm. The results of theoretical and experimental studies on the development and establishment of a system of ultraviolet disinfection of water for injection (UFOVI) intended for research sterilized water for injections. The pipe created a strong turbulent water flow. Performance irradiation laminar flow of 1.5 liters per second. Irradiation was carried out at three wavelengths 425 nm, 355 nm and 308 nm with energies semiconductor laser diode arrays to 4 MJ / cm3. Wavelength tuning implemented current in the range of 10 nm. For large capacities, we have developed a miniature solid state laser, which was used in fluid microorganisms inactivator. In the water treatment process breaks up to 98% of microbes, but can be left among pathogenic viruses destruction which requires special handling.

[Comparative organization and the origin of noncoding regulatory RNA genes from X-chromosome inactivation center of human and mouse].

PubMed

Kolesnikov, N N; Elisafenko, E A

2010-10-01

After the radiation of primates and rodents, the evolution of X-chromosome inactivation centers in human and mouse (XIC/Xic) followed two different directions. Human XIC followed the pathway towards transposon accumulation (the repeat proportion in the center constitutes 72%), especially LINEs, which prevail in the center. On the contrary, mouse Xic eliminated long repeats and accumulated species-specific SIN Es (the repeat proportion in the center constitutes 35%). The mechanism underlying inactivation of one of the X chromosomes in female mammals appeared on the basis of trasnsposons. The key gene of the inactivation process, XIST/Xist, similarly to other long noncoding RNA genes, like TSIX/Tsix, JPX/Jpx, and FTX/Ftx, was formed with the involvement of different transposon sequences. Furthermore, two clusters ofmicroRNA genes from inactivation center originated from L2 [1]. In mouse, one of such clusters has been preserved in the form of microRNA pseudogenes. Thus, long ncRNA genes and microRNAs appeared during the period of transposable elements expansion in this locus, 140 to 105 Myr ago, after the radiation of marsupials and placental mammal lineages.

THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION

PubMed Central

McDonald, Margaret R.

1955-01-01

The proteolytic activity of dilute solutions of clystalline trypsin is destroyed by x-rays, the amount of inactivation being an exponential function of the radiation dose. The reaction yield increases steadily with increasing concentration of trypsin, varying, as the concentration of enzyme is increased from 1 to 300 µM, from 0.068 to 0.958 micromole of trypsin per liter inactivated per 1000 r with 0.005 N hydrochloric acid as the solvent, from 0.273 to 0.866 with 0.005 N sulfuric acid as the solvent, and from 0.343 to 0.844 with 0.005 N nitric acid as the solvent. When the reaction yields are plotted as a function of the initial concentration of trypsin, they fall on a curve given by the expression Y α XK, in which Y is the reaction yield, X is the concentration of trypsin, and K is a constant equal to 0.46, 0.20, and 0.16, respectively, with 0.005 N hydrochloric, sulfuric, and nitric acids as solvents. The differences between the reaction yields found with chloride and sulfate ions in I to 10 µM trypsin solutions are significant only in the pH range from 2 to 4. The amount of inactivation obtained with a given dose of x-rays depends on the pH of the solution being irradiated and the nature of the solvent. The reaction yield-pH curve is a symmetrical one, with minimum yields at about pH 7. Buffers such as acetate, citrate, borate and barbiturate, and other organic molecules such as ethanol and glucose, in concentrations as low as 20 µM, inhibit the inactivation of trypsin by x-radiation. Sigmoid inactivation-dose curves instead of exponential ones are obtained in the presence of ethanol. The reaction yields for the inactivation of trypsin solutions by x-rays are approximately 1.5 times greater when the irradiation is done at 26°C. than when it is done at 5°C., when 0.005 N hydrochloric acid is the solvent. The dependence on temperature is less when 0.005 N sulfuric acid is used, and is negligible with 0.005 N nitric acid. The difficulties involved in interpreting radiation effects in aqueous systems, and in comparing the results obtained under different experimental conditions, are discussed. PMID:14367774

Promotion of initiated cells by radiation-induced cell inactivation.

PubMed

Heidenreich, W F; Paretzke, H G

2008-11-01

Cells on the way to carcinogenesis can have a growth advantage relative to normal cells. It has been hypothesized that a radiation-induced growth advantage of these initiated cells might be induced by an increased cell replacement probability of initiated cells after inactivation of neighboring cells by radiation. Here Monte Carlo simulations extend this hypothesis for larger clones: The effective clonal expansion rate decreases with clone size. This effect is stronger for the two-dimensional than for the three-dimensional situation. The clones are irregular, far from a circular shape. An exposure-rate dependence of the effective clonal expansion rate could come in part from a minimal recovery time of the initiated cells for symmetric cell division.

Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

NASA Astrophysics Data System (ADS)

Corash, Laurence; Lin, Lily; Wiesehahn, Gary; Cimino, George

1992-06-01

Transmission of viral diseases through blood products remains a problem in transfusion medicine. A number of methods have been developed to inactivate viral pathogens in plasma and plasma fractions, including: dry heating, wet heating, solvent-detergent treatment, and immunoaffinity purification. While some of these methods successfully inactivate pathogenic viruses, inactivation may be incomplete or result in damage to labile plasma proteins and cells. We have developed a photochemical decontamination system (PCD) for platelet concentrates (PC) utilizing treatment with long wavelength ultraviolet radiation (UVA, 320 - 400 nm) and 8-methoxypsoralen (8-MOP). This system is capable of inactivating 25 - 30 logs/hr of bacteria E. coli or S. aureus, 6 logs/hr of bacteriophage fd, 0.9 log/hr of bacteriophage R17 and 1.1 logs/hr of feline leukemia virus (FeLV) in PC. Immediately following 6 hrs of PCD treatment, platelet integrity and function of PCD treated and control PC were equivalent. After overnight storage PCD treated and control PC platelet properties were equal, but there was a slight reduction in TXB-2 production of PCD treated PC compared to controls. Following PCD treatment, PC were stored for 48 to 96 hrs. Platelet counts, morphology scores, extracellular LDH levels, aggregation response, dense body (db) content, and alpha granule ((alpha) g) content of PCD treated and control PC were comparable. We assessed the ability of the PCD technique to inactivate intracellular and extracellular virus, quantified the degree of DNA adduct formation in contaminating lymphocytes, and measured the inhibition of polymerase chain reaction (PCR) mediated amplification of intracellular DNA. High titers of cell-free murine cytomegalovirus added to human platelet concentrates (final concentration 106) were inactivated by PCD within 30 min. Cat renal fibroblasts infected at high levels with feline rhinotracheitis virus (FeRTV) were seeded into PC followed by PCD treatment with inactivation of 4.8 logs of FeRTV within 10 minutes. Purified human lymphocytes were seeded into PC and treated with PCD in the presence of 3H 8-MOP. Six hours of PCD treatment resulted in the formation of 9.3 to 12.8 8-MOP adducts per 1000 base pairs (bp) of DNA. PCR amplification of a 242 bp segment at the HLA-DQ(alpha) locus was examined. Inhibition of PCR DNA amplification was dependent on the numbers of 8-MOP adducts formed, and no amplification was present when greater than 12 adducts per 1000 bp were formed. These studies indicate that PCD can effectively inactivate high titers of cell-associated and cell-free virus seeded into standard human PC. The efficiency of DNA adduct formation can be quantitated, and the level of 8-MOP adduct formation in lymphocytes contaminating PC is comparable to the level of adduct formation in cellular DNA reported in the absence of platelets.

Photodynamic inactivation of conidia of the fungus Colletotrichum abscissum on Citrus sinensis plants with methylene blue under solar radiation.

PubMed

Gonzales, Júlia C; Brancini, Guilherme T P; Rodrigues, Gabriela B; Silva-Junior, Geraldo José; Bachmann, Luciano; Wainwright, Mark; Braga, Gilberto Ú L

2017-11-01

Antimicrobial photodynamic treatment (APDT) is a promising light based approach to control diseases caused by plant-pathogenic fungi. In the present study, we evaluated the effects of APDT with the phenothiazinium photosensitizer methylene blue (MB) under solar radiation on the germination and viability of conidia of the pathogenic fungus Colletotricum abscissum (former Colletotrichum acutatum sensu lato). Experiments were performed both on petals and leaves of sweet orange (Citrus sinensis) in different seasons and weather conditions. Conidial suspensions were deposited on the leaves and petals surface, treated with the PS (25 or 50μM) and exposed to solar radiation for only 30min. The effects of APDT on conidia were evaluated by counting the colony forming units recovered from leaves and petals and by direct evaluating conidial germination on the surface of these plant organs after the treatment. To better understand the mechanistic of conidial photodynamic inactivation, the effect of APDT on the permeability of the conidial plasma membrane was assessed using the fluorescent probe propidium iodide (PI) together with flow cytometry and fluorescence microscopy. APDT with MB and solar exposure killed C. abscissum conidia and prevented their germination on both leaves and petals of citrus. Reduction of conidial viability was up to three orders of magnitude and a complete photodynamic inactivation was achieved in some of the treatments. APDT damaged the conidial plasma membrane and increased its permeability to PI. No damage to sweet orange flowers or leaves was observed after APDT. The demonstration of the efficacy of APDT on the plant host represents a further step towards the use of the method for control phytopathogens in the field. Copyright © 2017 Elsevier B.V. All rights reserved.

Response of bacteria in wastewater sludge to moisture loss by evaporation and effect of moisture content on bacterial inactivation by ionizing radiation.

PubMed Central

Ward, R L; Yeager, J G; Ashley, C S

1981-01-01

Two studies were carried out to determine the influence of moisture content of the survival of bacteria in raw wastewater sludge. The first study involved the effect of water loss by evaporation on the bacterial population. The second used these dewatered samples to measure the effects of moisture content on the inactivation of bacteria sludge by ionizing radiation. Both studies involved survival measurements of six representative fecally associated bacteria grown separately in sterilized sludge as well as survival data on bacteria indigenous to sludge. Growth of bacteria was stimulated in sludge during the initial phase of moisture removal by evaporation, but the reduction of moisture content below about 50% by weight caused a proportional decrease in bacterial numbers. In comparison with the original sludge, this decrease reached about one-half to one order of magnitude in all dried samples except those containing Proteus mirabilis, which decreased about four orders of magnitude. The rates of inactivation of bacteria by ionizing radiation in sludge were usually modified to some degrees by variations in moisture content. Most bacteria were found to be somewhat protected from ionizing radiation at reduced moisture levels. The largest effect was found with Salmonella typhimurium, whose radiation resistance approximately doubled in dried sludge. However, no excessively large D10 values were found for any bacterial species tested. PMID:6789765

Deinococcus Mn2+-peptide complex: A novel approach to alphavirus vaccine development.

PubMed

Gayen, Manoshi; Gupta, Paridhi; Morazzani, Elaine M; Gaidamakova, Elena K; Knollmann-Ritschel, Barbara; Daly, Michael J; Glass, Pamela J; Maheshwari, Radha K

2017-06-22

Over the last ten years, Chikungunya virus (CHIKV), an Old World alphavirus has caused numerous outbreaks in Asian and European countries and the Americas, making it an emerging pathogen of great global health importance. Venezuelan equine encephalitis virus (VEEV), a New World alphavirus, on the other hand, has been developed as a bioweapon in the past due to its ease of preparation, aerosol dispersion and high lethality in aerosolized form. Currently, there are no FDA approved vaccines against these viruses. In this study, we used a novel approach to develop inactivated vaccines for VEEV and CHIKV by applying gamma-radiation together with a synthetic Mn-decapeptide-phosphate complex (MnDpPi), based on manganous-peptide-orthophosphate antioxidants accumulated in the extremely radiation-resistant bacterium Deinococcus radiodurans. Classical gamma-irradiated vaccine development approaches are limited by immunogenicity-loss due to oxidative damage to the surface proteins at the high doses of radiation required for complete virus-inactivation. However, addition of MnDpPi during irradiation process selectively protects proteins, but not the nucleic acids, from the radiation-induced oxidative damage, as required for safe and efficacious vaccine development. Previously, this approach was used to develop a bacterial vaccine. In the present study, we show that this approach can successfully be applied to protecting mice against viral infections. Irradiation of VEEV and CHIKV in the presence of MnDpPi resulted in substantial epitope preservation even at supra-lethal doses of gamma-rays (50,000Gy). Irradiated viruses were found to be completely inactivated and safe in vivo (neonatal mice). Upon immunization, VEEV inactivated in the presence of MnDpPi resulted in drastically improved protective efficacy. Thus, the MnDpPi-based gamma-inactivation approach described here can readily be applied to developing vaccines against any pathogen of interest in a fast and cost-effective manner. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Inactivation of biologically active dna by gamma ray induced superoxide radicals and their dismutation products singlet molecular oxygen and hydrogen peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanhemmen, J.J.; Meuling, W.J.A.

1975-01-01

The reactivity of gamma ray induced superoxide radicals and dismutation products (singlet molecular oxygen and hydrogen peroxide) with DNA were studied. Superoxide dismutase, which removes superoxide radicals and inhibits the formation of singlet oxygen, protects biologically active DNA (OX174 RF) against inactivation by ionizing radiation. Catalase, which removes hydrogen peroxide, also protects the DNA. Attempts with various chemical sources of singlet oxygen to determine whether this species inactivates DNA did not yield an unequivocal answer. It was concluded that a combination of the protonated form of the superoxide radical and hydrogen peroxide inactivates DNA. (Author) (GRA)

Ultraviolet disinfection of water for small water supplies

NASA Astrophysics Data System (ADS)

Carlson, D. A.; Seabloom, R. W.; Dewalle, F. B.; Wetzler, T. F.; Engeset, J.

1985-07-01

In the study ultraviolet radiation was considered as an alternative means of disinfection of small drinking water supplies. A major impetus for the study was the large increase in waterborne disease episodes in the United States whose etiologic agent, Giardia lamblia, was found to be highly resistant to conventional chlorination. While the germicidal effect of sunlight has long been known, it has been found that artificial UV radiation with a wavelength of 253.7 nm, can be produced by low pressure mercury vapor lamps. The inactivation of microorganisms by UV radiation is based upon photochemical reactions in DNA which result in errors in the coding system. Inactivation of microorganisms due to exposure to UV is proportional to the intensity multiplied by the time of exposure.

Radiation inactivation of Paenibacillus larvae and sterilization of American Foul Brood (AFB) infected hives using Co-60 gamma rays.

PubMed

De Guzman, Zenaida M; Cervancia, Cleofas R; Dimasuay, Kris Genelyn B; Tolentino, Mitos M; Abrera, Gina B; Cobar, Ma Lucia C; Fajardo, Alejandro C; Sabino, Noel G; Manila-Fajardo, Analinda C; Feliciano, Chitho P

2011-10-01

The effectiveness of gamma radiation in inactivating the Philippine isolate of Paenibacillus larvae was investigated. Spores of P. larvae were irradiated at incremental doses (0.1, 0.2, 0.4, 0.8 and 1.6 kGy) of gamma radiation emitted by a ⁶⁰Co source. Surviving spores were counted and used to estimate the decimal reduction (D₁₀) value. A dose of 0.2 kGy was sufficient to inactivate 90% of the total recoverable spores from an initial count of 10⁵- 9 × 10³ spores per glass plate. The sterilizing effect of high doses of gamma radiation on the spores of P. larvae in infected hives was determined. In this study, a minimum dose (D(min)) of 15 kGy was tested. Beehives with sub-clinical infections of AFB were irradiated and examined for sterility. All the materials were found to be free of P. larvae indicating its susceptibility to γ-rays. After irradiation, there were no visible changes in the physical appearance of the hives' body, wax and frames. Thus, a dose of 15 kGy is effective enough for sterilization of AFB-infected materials. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cryo-gamma radiation inactivation of bovine herpesvirus type-1

NASA Astrophysics Data System (ADS)

Degiorgi, C. Fernández; Smolko, E. E.; Lombardo, J. H.

1999-07-01

The radioresistance of bovine herpesvirus-1 (BHV-1), commonly known as infectious bovine rhinotracheitis virus (IBRV), suspended in free serum Glasgow-MEM medium and frozen at -78°C was studied. The number of surviving virus at a given dose of gamma-radiation was determined by a plaque assay system. D 10 values were calculated before and after removal of cell debris. The D 10 values obtained were 4.72 kGy and 7.31 kGy before and after removal of cell debris, respectively. Our results indicate that the inactivated viral particles could be used for vaccine preparation or diagnostic reagents.

Development and Testing of a Method for Validating Chemical Inactivation of Ebola Virus.

PubMed

Alfson, Kendra J; Griffiths, Anthony

2018-03-13

Complete inactivation of infectious Ebola virus (EBOV) is required before a sample may be removed from a Biosafety Level 4 laboratory. The United States Federal Select Agent Program regulations require that procedures used to demonstrate chemical inactivation must be validated in-house to confirm complete inactivation. The objective of this study was to develop a method for validating chemical inactivation of EBOV and then demonstrate the effectiveness of several commonly-used inactivation methods. Samples containing infectious EBOV ( Zaire ebolavirus ) in different matrices were treated, and the sample was diluted to limit the cytopathic effect of the inactivant. The presence of infectious virus was determined by assessing the cytopathic effect in Vero E6 cells. Crucially, this method did not result in a loss of infectivity in control samples, and we were able to detect less than five infectious units of EBOV ( Zaire ebolavirus ). We found that TRIzol LS reagent and RNA-Bee inactivated EBOV in serum; TRIzol LS reagent inactivated EBOV in clarified cell culture media; TRIzol reagent inactivated EBOV in tissue and infected Vero E6 cells; 10% neutral buffered formalin inactivated EBOV in tissue; and osmium tetroxide vapors inactivated EBOV on transmission electron microscopy grids. The methods described herein are easily performed and can be adapted to validate inactivation of viruses in various matrices and by various chemical methods.

Inactivation of B. subtilis spores by low pressure plasma—influence of optical filters and photon/particle fluxes on the inactivation efficiency

NASA Astrophysics Data System (ADS)

Fiebrandt, Marcel; Hillebrand, Bastian; Lackmann, Jan-Wilm; Raguse, Marina; Moeller, Ralf; Awakowicz, Peter; Stapelmann, Katharina

2018-01-01

Inactivation experiments were performed with Bacillus subtilis spores in a low pressure double inductively coupled plasma (DICP) system. Argon, nitrogen and oxygen at 5 Pa were used as feed gas to change the emission spectrum in the range of 100 nm to 400 nm, as well as between radical and metastable densities. Optical filters were applied, to block particles and selected wavelengths from the spores. By determining absolute photon fluxes, the sporicidal efficiency of various wavelength ranges was evaluated. The results showed good agreement with other plasma experiments, as well as with monochromatic light inactivation experiments from a synchrotron. The findings indicated that the inactivation rate constants of broadband plasma emission and monochromatic light were identical, and that no synergistic effect exists. Furthermore, the influence of radicals, ions and metastables on the inactivation efficiency was of minor importance in the set-up used, and radiation was the main reason for spore inactivation.

Inactivation of MS2 bacteriophage by streamer corona discharge in water.

PubMed

Lee, Changha; Kim, Jaeeun; Yoon, Jeyong

2011-02-01

Electrical discharge processes are emerging as water treatment technologies applicable to both the degradation of organic contaminants as well as inactivation of pathogens. Particularly as a disinfection technology, electrical discharge processes do not produce toxic byproducts, and effectively inactivate a wide spectrum of microorganisms by multiple lethal actions generated by the formation of plasma channels. This study demonstrates the inactivation of a virus using the streamer corona discharge process (SCDP) with MS2 phage as a surrogate. A rapid inactivation of MS2 phage (i.e., approximately 4 log inactivation in 5 min) was observed in all experimental runs conducted. Discharge conditions such as applied voltage and storage capacitance significantly affected the inactivation efficiency of MS2 phage, whereas the influence of water quality parameters was minor. In order to elucidate the mechanism of MS2 phage inactivation, potentially lethal factors that can be generated by the SCDP were selected, and their roles in the inactivation of MS2 phage were examined. As a result, effects of UV radiation, chemical oxidants, and pulsed electric fields were found to be insignificant. The shockwave generated upon plasma channel formation appears to be the most important factor responsible for MS2 phage inactivation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Stability and infectivity of cytolethal distending toxin type V gene-carrying bacteriophages in a water mesocosm and under different inactivation conditions.

PubMed

Allué-Guardia, Anna; Jofre, Juan; Muniesa, Maite

2012-08-01

Two cytolethal distending toxin (Cdt) type V-encoding bacteriophages (Φ62 and Φ125) were induced spontaneously from their wild-type Escherichia coli strains and from the lysogens generated in Shigella sonnei. The stability of Cdt phages was determined at various temperatures and pH values after 1 month of storage by means of infectivity tests using a plaque blot assay and analysis of phage genomes using real-time quantitative PCR (qPCR): both were highly stable. We assessed the inactivation of Cdt phages by thermal treatment, chlorination, UV radiation, and in a mesocosm in both summer and winter. The results for the two Cdt phages showed similar trends and were also similar to the phage SOM23 used for reference, but they showed a much higher persistence than Cdt-producing E. coli. Cdt phages showed maximal inactivation after 1 h at 70°C, 30 min of UV radiation, and 30 min of contact with a 10-ppm chlorine treatment. Inactivation in a mesocosm was higher in summer than in winter, probably because of solar radiation. The treatments reduced the number of infectious phages but did not have a significant effect on the Cdt phage particles detected by qPCR. Cdt phages were quantified by qPCR in 73% of river samples, and these results suggest that Cdt phages are a genetic vehicle and the natural reservoir for cdt in the environment.

Inactivation kinetics of foodborne pathogens by UV-C radiation and its subsequent growth in fresh-cut kailan-hybrid broccoli.

PubMed

Martínez-Hernández, Ginés Benito; Huertas, Juan-Pablo; Navarro-Rico, Javier; Gómez, Perla A; Artés, Francisco; Palop, Alfredo; Artés-Hernández, Francisco

2015-04-01

The inactivation of Escherichia coli, S. Enteritidis and Listeria monocytogenes after UV-C radiation with 0, 2.5, 5, 7.5, 10 and 15 kJ UV-C m(-2) on fresh-cut kailan-hybrid broccoli was explored. Inactivation did not follow linear kinetics. Hence, it was modelled by using the Weibull distribution function, obtaining adjusted R(2) values higher than 94%, indicative of the accuracy of the model to the experimental data. The UV-C doses needed to reduce 1 log cycle the E. coli, S. Enteritidis and L. monocytogenes counts were 1.07, 0.02 and 9.26 kJ m(-2), respectively, being S. Enteritidis the most sensitive microorganism to UV-C radiation while L. monocytogenes was the most resistant. According to experimental data, UV-C doses higher than 2.5 kJ m(-2) did not achieve great microbial reductions. No differences in the growth behaviour of these microorganisms was observed in the treated samples stored under air conditions at 5, 10 and 15 °C, compared to the control. Conclusively, low UV-C doses are effective to reduce E. coli, S. Enteritidis and L. monocytogenes populations in fresh-cut kailan-hybrid broccoli keeping such counts stable during shelf life at 5-10 °C. The current study provides inactivation models for these foodborne pathogens that can be used in microbial risk assessment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Qualitation and Quantitation on Microplasma Jet for Bacteria Inactivation.

PubMed

Du, ChangMing; Liu, Ya; Huang, YaNi; Li, ZiMing; Men, Rui; Men, Yue; Tang, Jun

2016-01-06

In this work, a self-made microplasma jet system was used to conduct the qualitation and quantitation of inactivation with Escherichia coli as the target bacteria. The logarithmic concentration and the size of antimicrobial rings served as the evaluation parameters, respectively. The effect of various parameters on inactivation effect was studied. The results showed that the majority of bacteria had been inactivated in 30 s. The inactivation effect enhanced and then weakened with the increase of air flow rate, and receded as the extension of treatment distance. The effect with different carrier gases showed as follows: oxygen > air > nitrogen > argon. Meanwhile, the effect of different components of microplasma was studied in the optimum conditions (The flow rate was 5 L/min; inactivation distance was 2 cm). The results showed that electrically neutral active species was the main factor of inactivation rather than heating effect, ultraviolet radiation and charged particles. Finally the experiments of thallus change proved that microplasma jet had etching effect on cell membrane. It also found that microplasma could degrade organic material like protein. Furthermore, the images of scanning electron microscope (SEM) revealed the change of cell morphology step by step in the whole process of inactivation.

Qualitation and Quantitation on Microplasma Jet for Bacteria Inactivation

NASA Astrophysics Data System (ADS)

Du, Changming; Liu, Ya; Huang, Yani; Li, Ziming; Men, Rui; Men, Yue; Tang, Jun

2016-01-01

In this work, a self-made microplasma jet system was used to conduct the qualitation and quantitation of inactivation with Escherichia coli as the target bacteria. The logarithmic concentration and the size of antimicrobial rings served as the evaluation parameters, respectively. The effect of various parameters on inactivation effect was studied. The results showed that the majority of bacteria had been inactivated in 30 s. The inactivation effect enhanced and then weakened with the increase of air flow rate, and receded as the extension of treatment distance. The effect with different carrier gases showed as follows: oxygen > air > nitrogen > argon. Meanwhile, the effect of different components of microplasma was studied in the optimum conditions (The flow rate was 5 L/min inactivation distance was 2 cm). The results showed that electrically neutral active species was the main factor of inactivation rather than heating effect, ultraviolet radiation and charged particles. Finally the experiments of thallus change proved that microplasma jet had etching effect on cell membrane. It also found that microplasma could degrade organic material like protein. Furthermore, the images of scanning electron microscope (SEM) revealed the change of cell morphology step by step in the whole process of inactivation.

Qualitation and Quantitation on Microplasma Jet for Bacteria Inactivation

PubMed Central

Du, ChangMing; Liu, Ya; Huang, YaNi; Li, ZiMing; Men, Rui; Men, Yue; Tang, Jun

2016-01-01

In this work, a self-made microplasma jet system was used to conduct the qualitation and quantitation of inactivation with Escherichia coli as the target bacteria. The logarithmic concentration and the size of antimicrobial rings served as the evaluation parameters, respectively. The effect of various parameters on inactivation effect was studied. The results showed that the majority of bacteria had been inactivated in 30 s. The inactivation effect enhanced and then weakened with the increase of air flow rate, and receded as the extension of treatment distance. The effect with different carrier gases showed as follows: oxygen > air > nitrogen > argon. Meanwhile, the effect of different components of microplasma was studied in the optimum conditions (The flow rate was 5 L/min; inactivation distance was 2 cm). The results showed that electrically neutral active species was the main factor of inactivation rather than heating effect, ultraviolet radiation and charged particles. Finally the experiments of thallus change proved that microplasma jet had etching effect on cell membrane. It also found that microplasma could degrade organic material like protein. Furthermore, the images of scanning electron microscope (SEM) revealed the change of cell morphology step by step in the whole process of inactivation. PMID:26732987

Feasibility of the silver-UV process for drinking water disinfection.

PubMed

Butkus, Michael A; Talbot, Mark; Labare, Michael P

2005-12-01

A synergistic effect between cationic silver and UV radiation (silver-UV disinfection) has been observed that can appreciably enhance inactivation of viruses. The purpose of this work was to assess the feasibility of this technique for drinking water disinfection and evaluate the effects of selected impurities, found in fresh water, and common parameters on inactivation of the coliphage MS-2 with the silver-UV process. Turbidity (kaolin), calcium hardness, carbonate alkalinity, and pH did not significantly degrade inactivation. Inactivation was reduced in the presence of chloride, at concentrations greater than 30 mg/L, and in water samples with UV-254 absorbance values greater than ca. 0.1 cm(-1). Inactivation of MS-2 with silver-UV disinfection was also reduced at high phosphate concentrations (above ca. 5 mM). Silver-UV inactivation of MS-2 increased with increases in temperature between 10 and 20 degrees C. Silver-UV inactivation of MS-2 was increased by greater than 1-log over UV alone, in two untreated fresh water sources, which indicates that silver-UV may be a viable treatment technology. An assessment of operation and management costs suggests that an increase in inactivation of MS-2 with silver-UV disinfection could be economically beneficial.

Innovative methods of energy transfer.

PubMed

McBee, L E

1996-09-01

Energy is utilized in many forms for processing egg products and other foods. Energy in the form of heat has commonly been used to kill microorganisms and pasteurize eggs. Transfer of energy by convection and conduction is limited by the properties of the egg product. Energy transfer by radiation is being used to advantage in the development of innovative methods to kill or inactivate microorganisms. A review of the electromagnetic spectrum reveals underutilized forms of energy with unique properties. Specific frequencies and method of application are selected for their ability to focus energy toward the destruction of microorganisms and the production of safe food products for the public.

Increased resistance to ionizing and ultraviolet radiation in Escherichia coli JM83 is associated with a chromosomal rearrangement.

PubMed

McLean, K M; Gutman, P D; Minton, K W; Clark, E P

1992-06-01

Cells cope with radiation damage through several mechanisms: (1) increased DNA repair activity, (2) scavenging and inactivation of radiation-induced radical molecules, and (3) entry into a G0-like quiescent state. We have investigated a chromosomal rearrangement to elucidate further the molecular and genetic mechanisms underlying these phenomena. A mutant of Escherichia coli JM83 (phi 80dlacZ delta M15) was isolated that demonstrated significantly increased resistance to both ionizing and ultraviolet radiation. Surviving fractions of mutant and wild-type cells were measured following exposure to standardized doses of radiation. Increased radioresistance was directly related to a chromosomal alteration near the bacteriophage phi 80 attachment site (attB), as initially detected by the LacZ- phenotype of the isolate. Southern hybridization of chromosomal DNA from the mutant and wild-type E. coli JM83 strains indicated that a deletion had occurred. We propose that the deletion near the attB locus produces the radioresistant phenotype of the E. coli JM83 LacZ- mutant, perhaps through the alteration or inactivation of a gene or its controlling element(s).

Inactivation of NADPH oxidases NOX4 and NOX5 protects human primary fibroblasts from ionizing radiation-induced DNA damage.

PubMed

Weyemi, Urbain; Redon, Christophe E; Aziz, Towqir; Choudhuri, Rohini; Maeda, Daisuke; Parekh, Palak R; Bonner, Michael Y; Arbiser, Jack L; Bonner, William M

2015-03-01

Human exposure to ionizing radiation from medical procedures has increased sharply in the last three decades. Recent epidemiological studies suggest a direct relationship between exposure to ionizing radiation and health problems, including cancer incidence. Therefore, minimizing the impact of radiation exposure in patients has become a priority in the development of future clinical practices. Crucial players in radiation-induced DNA damage include reactive oxygen species (ROS), but the sources of these have remained elusive. To the best of our knowledge, we show here for the first time that two members of the ROS-generating NADPH oxidase family (NOXs), NOX4 and NOX5, are involved in radiation-induced DNA damage. Depleting these two NOXs in human primary fibroblasts resulted in reduced levels of DNA damage as measured by levels of radiation-induced foci, a marker of DNA double-strand breaks (DSBs) and the comet assay coupled with increased cell survival. NOX involvement was substantiated with fulvene-5, a NOXs-specific inhibitor. Moreover, fulvene-5 mitigated radiation-induced DNA damage in human peripheral blood mononuclear cells ex vivo. Our results provide evidence that the inactivation of NOXs protects cells from radiation-induced DNA damage and cell death. These findings suggest that NOXs inhibition may be considered as a future pharmacological target to help minimize the negative effects of radiation exposure for millions of patients each year.

Inactivation of NADPH Oxidases NOX4 and NOX5 Protects Human Primary Fibroblasts from Ionizing Radiation-Induced DNA Damage

PubMed Central

Weyemi, Urbain; Redon, Christophe E.; Aziz, Towqir; Choudhuri, Rohini; Maeda, Daisuke; Parekh, Palak R.; Bonner, Michael Y.; Arbiser, Jack L.; Bonner, William M.

2015-01-01

Human exposure to ionizing radiation from medical procedures has increased sharply in the last three decades. Recent epidemiological studies suggest a direct relationship between exposure to ionizing radiation and health problems, including cancer incidence. Therefore, minimizing the impact of radiation exposure in patients has become a priority in the development of future clinical practices. Crucial players in radiation-induced DNA damage include reactive oxygen species (ROS), but the sources of these have remained elusive. To the best of our knowledge, we show here for the first time that two members of the ROS-generating NADPH oxidase family (NOXs), NOX4 and NOX5, are involved in radiation-induced DNA damage. Depleting these two NOXs in human primary fibroblasts resulted in reduced levels of DNA damage as measured by levels of radiation-induced foci, a marker of DNA double-strand breaks (DSBs) and the comet assay coupled with increased cell survival. NOX involvement was substantiated with fulvene-5, a NOXs-specific inhibitor. Moreover, fulvene-5 mitigated radiation-induced DNA damage in human peripheral blood mononuclear cells ex vivo. Our results provide evidence that the inactivation of NOXs protects cells from radiation-induced DNA damage and cell death. These findings suggest that NOXs inhibition may be considered as a future pharmacological target to help minimize the negative effects of radiation exposure for millions of patients each year. PMID:25706776

Optical Properties of Three Beach Waters: Implications for Predictive Modeling of Enterococci

EPA Science Inventory

Sunlight plays an important role in the inactivation of fecal indicator bacteria in recreational waters. Solar radiation can explain temporal trends in bacterial counts and is commonly used as an explanatory variable in predictive models. Broadband surface radiation provides a ba...

Limnoithona sinensis as refuge for bacteria: protection from UV radiation and chlorine disinfection in drinking water treatment.

PubMed

Lin, Tao; Cai, Bo; Chen, Wei

2014-11-01

In this study, we tested the potential of Limnoithona sinensis to provide its attached bacteria refuge against disinfection. The experimental results indicated that in water devoid of zooplankton, both UV radiation and chlorine disinfection significantly decreased the viability of free-living bacteria. In the presence of L. sinensis, however, the attached bacteria could survive and rapidly recover from disinfection. This demonstrated that L. sinensis provided protection from external damage to various aquatic bacteria that were attached to its body. The surviving bacteria remained on L. sinensis after disinfection exposure, which enabled a rapid increase in the bacterial population followed by their subsequent release into the surrounding water. Compared with UV radiation, chlorine disinfection was more effective in terms of inactivating attached bacteria. Both UV radiation and chlorine disinfection had little effect in terms of preventing the spread of undesirable bacteria, due to the incomplete inactivation of the bacteria associated with L. sinensis.

Cross-Resistance of UV- or Chlorine Dioxide-Resistant Echovirus 11 to Other Disinfectants

PubMed Central

Zhong, Qingxia; Carratalà, Anna; Ossola, Rachele; Bachmann, Virginie; Kohn, Tamar

2017-01-01

The emergence of waterborne viruses with resistance to disinfection has been demonstrated in the laboratory and in the environment. Yet, the implications of such resistance for virus control remain obscure. In this study we investigate if viruses with resistance to a given disinfection method exhibit cross-resistance to other disinfectants. Chlorine dioxide (ClO2)- or UV-resistant populations of echovirus 11 were exposed to five inactivating treatments (free chlorine, ClO2, UV radiation, sunlight, and heat), and the extent of cross-resistance was determined. The ClO2-resistant population exhibited cross-resistance to free chlorine, but to none of the other inactivating treatments tested. We furthermore demonstrated that ClO2 and free chlorine act by a similar mechanism, in that they mainly inhibit the binding of echovirus 11 to its host cell. As such, viruses with host binding mechanisms that can withstand ClO2 treatment were also better able to withstand oxidation by free chlorine. Conversely, the UV-resistant population was not significantly cross-resistant to any other disinfection treatment. Overall, our results indicate that viruses with resistance to multiple disinfectants exist, but that they can be controlled by inactivating methods that operate by a distinctly different mechanism. We therefore suggest to utilize two disinfection barriers that act by different mechanisms in order to control disinfection-resistant viruses. PMID:29046672

Microencapsulated antimicrobial compounds as a means to enhance electron beam irradiation treatment for inactivation of pathogens on fresh spinach leaves.

PubMed

Gomes, Carmen; Moreira, Rosana G; Castell-Perez, Elena

2011-08-01

Recent outbreaks associated to the consumption of raw or minimally processed vegetable products that have resulted in several illnesses and a few deaths call for urgent actions aimed at improving the safety of those products. Electron beam irradiation can extend shelf-life and assure safety of fresh produce. However, undesirable effects on the organoleptic quality at doses required to achieve pathogen inactivation limit irradiation. Ways to increase pathogen radiation sensitivity could reduce the dose required for a certain level of microbial kill. The objective of this study was to evaluate the effectiveness of using natural antimicrobials when irradiating fresh produce. The minimum inhibitory concentration of 5 natural compounds and extracts (trans-cinnamaldehyde, eugenol, garlic extract, propolis extract, and lysozyme with ethylenediaminetetraacetate acid (disodium salt dihydrate) was determined against Salmonella spp. and Listeria spp. In order to mask odor and off-flavor inherent of several compounds, and to increase their solubility, complexes of these compounds and extracts with β-cyclodextrin were prepared by the freeze-drying method. All compounds showed bacteriostatic effect at different levels for both bacteria. The effectiveness of the microencapsulated compounds was tested by spraying them on the surface of baby spinach inoculated with Salmonella spp. The dose (D₁₀ value) required to reduce the bacterial population by 1 log was 0.190 kGy without antimicrobial addition. The increase in radiation sensitivity (up to 40%) varied with the antimicrobial compound. These results confirm that the combination of spraying microencapsulated antimicrobials with electron beam irradiation was effective in increasing the killing effect of irradiation. Foodborne illness outbreaks attributed to fresh produce consumption have increased and present new challenges to food safety. Current technologies (water washing or treating with 200 ppm chlorine) cannot eliminate internalized pathogens. Ionizing radiation is a viable alternative for eliminating pathogens; however, the dose required to inactivate these pathogens is often too high to be tolerated by the fresh produce without undesirable quality changes. This study uses natural antimicrobial ingredients as radiosensitizers. These ingredients were encapsulated and applied to fresh produce that was subsequently irradiated. The process results in high level of microorganism inactivation using lower doses than the conventional irradiation treatments. © 2011 Institute of Food Technologists®

Astrophysical and biological constraints on radiopanspermia.

PubMed

Secker, J; Wesson, P S; Lepock, J R

1996-08-01

We have carried out a series of calculations involving bacteria and viruses embedded in dust grains, which are ejected from our solar system by radiation pressure and travel through space to other star systems. Under many conditions this type of panspermia is impractical, primarily because the ultraviolet (UV) radiation of the present Sun inactivates the micro-organisms. However, if the organisms are shielded by an absorbing material like carbon and if ejection takes place in the red-giant phase of a one solar mass star like our Sun, there is a significant probability that the micro-organisms can reach another star system alive (i.e. with only sub-lethal damage from UV and ionizing radiation). In addition to panspermia with viable micro-organisms, it is possible to seed the Galaxy with inactivated ones whose DNA and RNA fragments may provide the initial information necessary to start biological evolution in favourable environments.

Virus inactivation studies using ion beams, electron and gamma irradiation

NASA Astrophysics Data System (ADS)

Smolko, Eduardo E.; Lombardo, Jorge H.

2005-07-01

Known methods of virus inactivation are based on the chemical action of some substances such as acetylethylenimine, betapropiolactone, glycidalaldehyde, formaldehyde, etc. In such a process, the viral suspension should be kept at room or higher temperatures for 24-48 h. Under these conditions, physical and chemical agents act to degrade the virus antigenic proteins. On the contrary with ionizing radiations at low temperatures, the treatment does not cause such degradation allowing the study of different viral functions. In this work, particle (α, d and ß) and γ irradiations were used for partial and total inactivation of Foot and Mouth Disease Virus (FMDV), Rauscher Leukemia Virus (RLV) and Herpes Simplex Virus (HSV). Obtention of the D37 dose from survival curves and the application of the target theory, permitted the determination of molecular weight of the nucleic acid genomes, EBR values and useful information for vaccine preparation. For RLV virus, a two target model of the RNA genome was deduced in accordance with biological information while from data from the literature and our own work on the structure of the scrapie prion, considering the molecular weight obtained by application of the theory, a new model for prion replication is presented, based on a trimer molecule.

Inactivation of foodborne pathogens on crawfish tail meat using cryogenic freezing and gamma radiation

USDA-ARS?s Scientific Manuscript database

Foodborne illness outbreaks occasionally occur as a result of microbiologically contaminated crustaceans, including crawfish. Cryogenic freezing and gamma radiation are two technologies which can be used to improve the microbiological safety and shelf-life of foods. In the U.S. the majority of non-c...

Chemical-free inactivated whole influenza virus vaccine prepared by ultrashort pulsed laser treatment

NASA Astrophysics Data System (ADS)

Tsen, Shaw-Wei David; Donthi, Nisha; La, Victor; Hsieh, Wen-Han; Li, Yen-Der; Knoff, Jayne; Chen, Alexander; Wu, Tzyy-Choou; Hung, Chien-Fu; Achilefu, Samuel; Tsen, Kong-Thon

2015-05-01

There is an urgent need for rapid methods to develop vaccines in response to emerging viral pathogens. Whole inactivated virus (WIV) vaccines represent an ideal strategy for this purpose; however, a universal method for producing safe and immunogenic inactivated vaccines is lacking. Conventional pathogen inactivation methods such as formalin, heat, ultraviolet light, and gamma rays cause structural alterations in vaccines that lead to reduced neutralizing antibody specificity, and in some cases, disastrous T helper type 2-mediated immune pathology. We have evaluated the potential of a visible ultrashort pulsed (USP) laser method to generate safe and immunogenic WIV vaccines without adjuvants. Specifically, we demonstrate that vaccination of mice with laser-inactivated H1N1 influenza virus at about a 10-fold lower dose than that required using conventional formalin-inactivated influenza vaccines results in protection against lethal H1N1 challenge in mice. The virus, inactivated by the USP laser irradiation, has been shown to retain its surface protein structure through hemagglutination assay. Unlike conventional inactivation methods, laser treatment did not generate carbonyl groups in protein, thereby reducing the risk of adverse vaccine-elicited T helper type 2 responses. Therefore, USP laser treatment is an attractive potential strategy to generate WIV vaccines with greater potency and safety than vaccines produced by current inactivation techniques.

Effect of electron beam and gamma radiation on drug-susceptible and drug-resitant listeria monocytogenes strains in salmon under different temperature.

PubMed

Skowron, Krzysztof; Grudlewska, Katarzyna; Gryń, Grzegorz; Skowron, Karolina Jadwiga; Świeca, Agnieszka; Paluszak, Zbigniew; Zimek, Zbigniew; Rafalski, Andrzej; Gospodarek-Komkowska, Eugenia

2018-05-04

To investigate the effect of gamma radiation and high energy electron beam doses on the inactivation of antibiotic-susceptible and antibiotic-resistant Listeria monocytogenes strains inoculated on the surface of raw salmon fillets stored at different temperature (-20°C, 4°C and 25°C). The population of bacteria strains resistance to penicillin, ampicillin, meropenem, erythromycin and trimethoprim-sulfamethoxazole was generated. When using gamma irradiation, the theoretical lethal dose ranged from 1.44 to 5.68 kGy and for electron beam the values ranged from 2.99 to 6.83 kGy. The theoretical lethal dose for both radiation methods was higher for antibiotic-resistant strains. Gamma radiation proved to be a more effective method for extending salmon fillet shelf-life. The evaluation of PFGE electrophoregram revealed that the repair of radiation-caused DNA damage occurred faster in antibiotic-resistant L. monocytogenes strains. The number of live L. monocytogenes cells, 40 hours after irradiation, also was higher in antibiotic-resistant strain suspension. The present study showed that gamma radiation was more effective in the elimination of the tested microorganisms and food preservation, than a high energy electron beam. The antibiotic-resistant L. monocytogenes strains were more resistant to both radiation methods. There are a lot of research on the effect of radiation on the number of bacteria in food products. However, there is almost no information about the effect of strain properties, such as drug susceptibility, virulence, etc., on their resistance to ionizing radiation. An increasing number of drug resistant bacterial strains isolated from food, encourages to take up this research subject. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

mBAND analysis for high- and low-LET radiation-induced chromosome aberrations: a review.

PubMed

Hada, Megumi; Wu, Honglu; Cucinotta, Francis A

2011-06-03

During long-term space travel or cancer therapy, humans are exposed to high linear energy transfer (LET) energetic heavy ions. High-LET radiation is much more effective than low-LET radiation in causing various biological effects, including cell inactivation, genetic mutations, cataracts and cancer induction. Most of these biological endpoints are closely related to chromosomal damage, and cytogenetic damage can be utilized as a biomarker for radiation insults. Epidemiological data, mainly from survivors of the atomic bomb detonations in Japan, have enabled risk estimation from low-LET radiation exposures. The identification of a cytogenetic signature that distinguishes high- from low-LET exposure remains a long-term goal in radiobiology. Recently developed fluorescence in situ hybridization (FISH)-painting methodologies have revealed unique endpoints related to radiation quality. Heavy-ions induce a high fraction of complex-type exchanges, and possibly unique chromosome rearrangements. This review will concentrate on recent data obtained with multicolor banding in situ hybridization (mBAND) methods in mammalian cells exposed to low- and high-LET radiations. Chromosome analysis with mBAND technique allows detection of both inter- and intrachromosomal exchanges, and also distribution of the breakpoints of aberrations. 2011 Elsevier B.V. All rights reserved.

Inactivation of human norovirus and Tulane virus in simple media and fresh whole strawberries by ionizing radiation.

PubMed

DiCaprio, Erin; Phantkankum, Nuttapong; Culbertson, Doug; Ma, Yuanmei; Hughes, John H; Kingsley, David; Uribe, Roberto M; Li, Jianrong

2016-09-02

Human norovirus (NoV) is a major cause of fresh produce-associated outbreaks and human NoV in irrigation water can potentially lead to viral internalization in fresh produce. Therefore, there is a need to develop novel intervention strategies to target internalized viral pathogens while maintaining fresh produce quality. In this study electron beam (E-beam) and gamma radiation were evaluated for efficacy against a human NoV GII.4 strain and Tulane virus (TV). Virus survival following ionizing radiation treatments was determined using direct quantitative reverse transcriptase PCR (RT-qPCR), the porcine gastric mucin magnetic bead (PGM-MB) binding assay followed by RT-qPCR, and plaque assay. In simple media, a high dose of E-beam treatment was required to completely abolish the receptor binding ability of human NoV (35.3kGy) and TV (19.5-24.1kGy), as assessed using the PGM-MB binding assay. Both human NoV and TV were more susceptible to gamma irradiation than E-beam, requiring 22.4kGy to achieve complete inactivation. In whole strawberries, no human NoV or TV RNA was detected following 28.7kGy of E-beam treatment using the PGM-MB binding assay. Overall, human NoV and TV are highly resistant to ionizing radiation and therefore the technology may not be suitable to eliminate viruses in fresh produce at the currently approved levels. In addition, the PGM-MB binding assay is an improved method to detect viral infectivity compared to direct RT-qPCR. Copyright © 2016. Published by Elsevier B.V.

Mesenchymal stromal cells having inactivated RB1 survive following low irradiation and accumulate damaged DNA: Hints for side effects following radiotherapy.

PubMed

Alessio, Nicola; Capasso, Stefania; Di Bernardo, Giovanni; Cappabianca, Salvatore; Casale, Fiorina; Calarco, Anna; Cipollaro, Marilena; Peluso, Gianfranco; Galderisi, Umberto

2017-02-01

Following radiotherapy, bone sarcomas account for a significant percentage of recurring tumors. This risk is further increased in patients with hereditary retinoblastoma that undergo radiotherapy. We analyzed the effect of low and medium dose radiation on mesenchymal stromal cells (MSCs) with inactivated RB1 gene to gain insights on the molecular mechanisms that can induce second malignant neoplasm in cancer survivors. MSC cultures contain subpopulations of mesenchymal stem cells and committed progenitors that can differentiate into mesodermal derivatives: adipocytes, chondrocytes, and osteocytes. These stem cells and committed osteoblast precursors are the cell of origin in osteosarcoma, and RB1 gene mutations have a strong role in its pathogenesis. Following 40 and 2000 mGy X-ray exposure, MSCs with inactivated RB1 do not proliferate and accumulate high levels of unrepaired DNA as detected by persistence of gamma-H2AX foci. In samples with inactivated RB1 the radiation treatment did not increase apoptosis, necrosis or senescence versus untreated cells. Following radiation, CFU analysis showed a discrete number of cells with clonogenic capacity in cultures with silenced RB1. We extended our analysis to the other members of retinoblastoma gene family: RB2/P130 and P107. Also in the MSCs with silenced RB2/P130 and P107 we detected the presence of cells with unrepaired DNA following X-ray irradiation. Cells with unrepaired DNA may represent a reservoir of cells that may undergo neoplastic transformation. Our study suggests that, following radiotherapy, cancer patients with mutations of retinoblastoma genes may be under strict controls to evaluate onset of secondary neoplasms following radiotherapy.

Effect of microwave radiation on inactivation of Clostridium sporogenes (PA 3679) spores.

PubMed Central

Welt, B A; Tong, C H; Rossen, J L; Lund, D B

1994-01-01

Three techniques for studying effects of microwave radiation on microorganisms were introduced. Spores of Clostridium sporogenes (PA 3679) were chosen as a test organism because the kinetic parameters for thermal inactivation are well known and because of the importance of the genus Clostridium to the food industry. For the first technique, a specially designed kinetics vessel was used to compare inactivation rates of microwave-heated and conventionally heated spores at steady-state temperatures of 90, 100, and 110 degrees C. Rates were found to be similar at the 95% confidence level. The second and third techniques were designed to study the effect of relatively high power microwave exposure at sublethal temperatures. In the second approach, the suspension was continuously cooled via direct contact with a copper cooling coil in a well-mixed vessel, outside the microwave oven. The suspension was pumped through a Teflon loop in the oven, where it continuously absorbed approximately 400 W of microwave power. Inactivation occurred in both irradiated and unirradiated samples. It was suspected that copper ions entered the suspension from the copper coil and were toxic to the spores. The fact that the results were similar, however, implied the absence of nonthermal microwave effects. In the third approach, the copper coil was replaced with a silicone tubing loop in a microwave transparent vessel. The suspension was continuously irradiated at 150 W of microwave power. No detectable inactivation occurred. Results indicated that the effect of microwave energy on viability of spores was indistinguishable from the effect of conventional heating. PMID:8135512

Effects of Bacterial Inactivation Methods on Downstream Proteomic Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Andy; Merkley, Eric D.; Clowers, Brian H.

2015-05-01

Inactivation of pathogenic microbial samples is often necessary for the protection of researchers and to comply with local and federal regulations. By its nature, biological inactivation causes changes to microbial samples, potentially affecting observed experimental results. While inactivation induced damage to materials such as DNA has been evaluated, the effect of various inactivation strategies on proteomic data, to our knowledge, has not been discussed. To this end, we inactivated samples of Yersinia pestis and Escherichia coli by autoclave, ethanol, or irradiation treatment to determine how inactivation changes liquid chromatography tandem mass spectrometry data quality as well as apparent protein contentmore » of cells. Proteomic datasets obtained from aliquots of samples inactivated by different methods were highly similar, with Pearson correlation coefficients ranging from 0.822 to 0.985 and 0.816 to 0.985 for E. coli and Y. pestis, respectively, suggesting that inactivation had only slight impacts on the set of proteins identified. In addition, spectral quality metrics such as distributions of various database search algorithm scores remained constant across inactivation methods, indicating that inactivation does not appreciably degrade spectral quality. Though overall changes resulting from inactivation were small, there were detectable trends. For example, one-sided Fischer exact tests determined that periplasmic proteins decrease in observed abundance after sample inactivation by autoclaving (α = 1.71x10-2 for E. coli, α = 4.97x10-4 for Y. pestis) and irradiation (α = 9.43x10-7 for E. coli, α = 1.21x10-5 for Y. pestis) when compared to controls that were not inactivated. Based on our data, if sample inactivation is necessary, we recommend inactivation with ethanol treatment with secondary preference given to irradiation.« less

Deinococcus Mn2+ -Peptide Complex: A Novel Approach to Alphavirus Vaccine Development

DTIC Science & Technology

2016-08-05

immunogenicity loss due to oxidative damage to the surface proteins at the high doses of radiation required for complete virus inactivation. Thus, we...bacteria Deinococcus radiodurans) in the present study which selectively protects proteins but not the nucleic acid from the radiation - induced...presence of MDP have significant epitope preservation even at supra-lethal doses of radiation . Irradiated viruses were found to be completely

Disinfection of Airborne Organisms by Ultraviolet-C Radiation and Sunlight

DTIC Science & Technology

2012-07-01

organisms deposited on surfaces, suspended in water , and contaminating food, all of which have been discussed elsewhere (Block, 2001). In contrast, the... water . Therefore, the primary means for organism inactivation in aerosols is ultraviolet (UV) radiation. Radiation from the sunlight is used as a...cortex is essential for reduction of the water content in the spore core and formation of a dormant spore. The cortex is degraded in spore

Inactivation of Staphylococcus saprophyticus in chicken meat and exudate using high pressure processing, gamma radiation, and ultraviolet light

USDA-ARS?s Scientific Manuscript database

Stapylococcus saprophyticus is a common contaminant in foods and causes urinary tract infections in humans. Three nonthermal food safety intervention technologies used to improve the safety foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). A...

Inactivation credit of UV radiation for viruses, bacteria and protozoan (oo)cysts in water: a review.

PubMed

Hijnen, W A M; Beerendonk, E F; Medema, G J

2006-01-01

UV disinfection technology is of growing interest in the water industry since it was demonstrated that UV radiation is very effective against (oo)cysts of Cryptosporidium and Giardia, two pathogenic micro-organisms of major importance for the safety of drinking water. Quantitative Microbial Risk Assessment, the new concept for microbial safety of drinking water and wastewater, requires quantitative data of the inactivation or removal of pathogenic micro-organisms by water treatment processes. The objective of this study was to review the literature on UV disinfection and extract quantitative information about the relation between the inactivation of micro-organisms and the applied UV fluence. The quality of the available studies was evaluated and only high-quality studies were incorporated in the analysis of the inactivation kinetics. The results show that UV is effective against all waterborne pathogens. The inactivation of micro-organisms by UV could be described with first-order kinetics using fluence-inactivation data from laboratory studies in collimated beam tests. No inactivation at low fluences (offset) and/or no further increase of inactivation at higher fluences (tailing) was observed for some micro-organisms. Where observed, these were included in the description of the inactivation kinetics, even though the cause of tailing is still a matter of debate. The parameters that were used to describe inactivation are the inactivation rate constant k (cm(2)/mJ), the maximum inactivation demonstrated and (only for bacterial spores and Acanthamoeba) the offset value. These parameters were the basis for the calculation of the microbial inactivation credit (MIC="log-credits") that can be assigned to a certain UV fluence. The most UV-resistant organisms are viruses, specifically Adenoviruses, and bacterial spores. The protozoon Acanthamoeba is also highly UV resistant. Bacteria and (oo)cysts of Cryptosporidium and Giardia are more susceptible with a fluence requirement of <20 mJ/cm(2) for an MIC of 3 log. Several studies have reported an increased UV resistance of environmental bacteria and bacterial spores, compared to lab-grown strains. This means that higher UV fluences are required to obtain the same level of inactivation. Hence, for bacteria and spores, a correction factor of 2 and 4 was included in the MIC calculation, respectively, whereas some wastewater studies suggest that a correction of a factor of 7 is needed under these conditions. For phages and viruses this phenomenon appears to be of little significance and for protozoan (oo)cysts this aspect needs further investigation. Correction of the required fluence for DNA repair is considered unnecessary under the conditions of drinking water practice (no photo-repair, dark repair insignificant, esp. at higher (60 mJ/cm(2)) fluences) and probably also wastewater practice (photo-repair limited by light absorption). To enable accurate assessment of the effective fluence in continuous flow UV systems in water treatment practice, biodosimetry is still essential, although the use of computational fluid dynamics (CFD) improves the description of reactor hydraulics and fluence distribution. For UV systems that are primarily dedicated to inactivate the more sensitive pathogens (Cryptosporidium, Giardia, pathogenic bacteria), additional model organisms are needed to serve as biodosimeter.

Response surface methodology as a tool for modeling and optimization of Bacillus subtilis spores inactivation by UV/ nano-Fe0 process for safe water production.

PubMed

Yousefzadeh, Samira; Matin, Atiyeh Rajabi; Ahmadi, Ehsan; Sabeti, Zahra; Alimohammadi, Mahmood; Aslani, Hassan; Nabizadeh, Ramin

2018-04-01

One of the most important aspects of environmental issues is the demand for clean and safe water. Meanwhile, disinfection process is one of the most important steps in safe water production. The present study aims at estimating the performance of UV, nano Zero-Valent Iron particles (nZVI, nano-Fe 0 ), and UV treatment with the addition of nZVI (combined process) for Bacillus subtilis spores inactivation. Effects of different factors on inactivation including contact time, initial nZVI concentration, UV irradiance and various aerations conditions were investigated. Response surface methodology, based on a five-level, two variable central composite design, was used to optimize target microorganism reduction and the experimental parameters. The results indicated that the disinfection time had the greatest positive impact on disinfection ability among the different selected independent variables. According to the results, it can be concluded that microbial reduction by UV alone was more effective than nZVI while the combined UV/nZVI process demonstrated the maximum log reduction. The optimum reduction of about 4 logs was observed at 491 mg/L of nZVI and 60 min of contact time when spores were exposed to UV radiation under deaerated condition. Therefore, UV/nZVI process can be suggested as a reliable method for Bacillus subtilis spores inactivation. Copyright © 2018. Published by Elsevier Ltd.

Calculation of Heavy Ion Inactivation and Mutation Rates in Radial Dose Model of Track Structure

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Wilson, John W.; Shavers, Mark R.; Katz, Robert

1997-01-01

In the track structure model, the inactivation cross section is found by summing an inactivation probability over all impact parameters from the ion to the sensitive sites within the cell nucleus. The inactivation probability is evaluated by using the dose response of the system to gamma rays and the radial dose of the ions and may be equal to unity at small impact parameters. We apply the track structure model to recent data with heavy ion beams irradiating biological samples of E. Coli, B. Subtilis spores, and Chinese hamster (V79) cells. Heavy ions have observed cross sections for inactivation that approach and sometimes exceed the geometric size of the cell nucleus. We show how the effects of inactivation may be taken into account in the evaluation of the mutation cross sections in the track structure model through correlation of sites for gene mutation and cell inactivation. The model is fit to available data for HPRT (hypoxanthine guanine phosphoribosyl transferase) mutations in V79 cells, and good agreement is found. Calculations show the high probability for mutation by relativistic ions due to the radial extension of ions track from delta rays. The effects of inactivation on mutation rates make it very unlikely that a single parameter such as LET (linear energy transfer) can be used to specify radiation quality for heavy ion bombardment.

Effects of track structure and cell inactivation on the calculation of heavy ion mutation rates in mammalian cells

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Wilson, J. W.; Shavers, M. R.; Katz, R.

1996-01-01

It has long been suggested that inactivation severely effects the probability of mutation by heavy ions in mammalian cells. Heavy ions have observed cross sections of inactivation that approach and sometimes exceed the geometric size of the cell nucleus in mammalian cells. In the track structure model of Katz the inactivation cross section is found by summing an inactivation probability over all impact parameters from the ion to the sensitive sites within the cell nucleus. The inactivation probability is evaluated using the dose-response of the system to gamma-rays and the radial dose of the ions and may be equal to unity at small impact parameters for some ions. We show how the effects of inactivation may be taken into account in the evaluation of the mutation cross sections from heavy ions in the track structure model through correlation of sites for gene mutation and cell inactivation. The model is fit to available data for HPRT mutations in Chinese hamster cells and good agreement is found. The resulting calculations qualitatively show that mutation cross sections for heavy ions display minima at velocities where inactivation cross sections display maxima. Also, calculations show the high probability of mutation by relativistic heavy ions due to the radial extension of ions track from delta-rays in agreement with the microlesion concept. The effects of inactivation on mutations rates make it very unlikely that a single parameter such as LET or Z*2/beta(2) can be used to specify radiation quality for heavy ion bombardment.

Radiation resistence of microorganisms from radiation sterilization processing environments

NASA Astrophysics Data System (ADS)

Sabovljev, Svetlana A.; Žunić, Zora S.

The radiation resistance of microorganisms was examined on the samples of dust collected from the radiation sterilization processing environments including assembly, storage, and sterilization plant areas. The isolation of radiation resistant strains was performed by irradiation with screening doses ranging from 10 to 35 kGy and test pieces containing 10 6 to 10 8 CFU in dried serum-broth, representing 100 to 5000 colonies of primary cultures of microorganisms from 7 different sites. In an examination of 16900 colonies of aerobic microorganisms from 3 hygienically controlled production sites and 4 uncontrolled ones, 30 strains of bacteria were isolated. Of those 15 were classified as genus Bacillus, 9 as Micrococcus and 6 as Sarcina. All of the 15 strains of Gram positive sporeforming aerobic rods exhibited an exponential decrease in the surviving fraction as a function of dose, indicating that the inactivation of spores of aerobic rods is a consequence of a single energy deposition into the target. All strains were found to be moderately resistant to radiation with D-6 values (dose required to reduce survival to 6 log cycles) between 18 and 26 kGy. All of the isolated Gram positive cocci showed inactivation curves having a shoulder, indicating that different processes are involved in the inactivation of these cells, e.g. accumulation of sublethal lesions, or final repair capacity of potential lethal lesions. Moderate radiation resistance was observed in 13 strains with D-6 values between 16 to 30 kGy. Two slow-growing, red pigmented strains tentatively classified as genus Micrococcus isolated from uncontrolled sites (human dwellings) were exceptionally resistant with D-6 more than 45 kGy. For hygienically controlled sites, Gram positive spereforming rods composed two thirds of the resistant microflora, while Gram positive cocci comprised one third. For hygienically uncontrolled sites this ratio was reversed. An assumption is made that one isolated strain has grown up from one CFU in the original microflora. In the light of the observed proportion of radiation resistant bacteria in microflora from hygienically controlled radiation sterilization processing environments, and assuming an initial contamination of 50 CFU per product unit, there is no more than one chance of a contaminated item remaining within a population of 10 7 items subjected to sterilization by exposure to a radiation dose of 25 kGy.

Eradication of bacterial species via photosensitization

NASA Astrophysics Data System (ADS)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1999-02-01

Photosensitization and inactivation efficacy of three bacterial species: Prevotella nigrescens, Staphylococcus aureus and Escherichia coli have been investigated. Samples of Staphylococcus aureus and Escherichia coli were treated with the triphenylmethane dye malachite green isothiocyanate and exposed to light from a variety of continuous and pulsed light sauces at a wavelength of approximately 630 nm. Inactivation of the Gram-positive species Staphylococcus aureus was found to increase with radiation dose, whilst Gram-negative Escherichia coli was resistant to such treatment. Samples of the pigmented species Prevotella nigrescens were found to be inactivated by exposure to light alone. The mechanism of photosensitization and inactivation of Staphylococcus aureus with malachite green isothiocyanate is addressed. The possible roles of the excited triplet state of the photosensitizer, the involvement of molecular oxygen, and the bacterial cell wall are discussed. Photosensitization may provide a way of eliminating naturally pigmented species responsible for a variety of infections, including oral diseases such as gingivitis and periodontitis.

Thermal Contribution to the Inactivation of Cryptosporidium in Plastic Bottles during Solar Water Disinfection Procedures

PubMed Central

Gómez-Couso, Hipólito; Fontán-Sainz, María; Ares-Mazás, Elvira

2010-01-01

To determine the thermal contribution, independent of ultraviolet radiation, on the inactivation of Cryptosporidium parvum during solar water disinfection procedures (SODIS), oocysts were exposed for 4, 8, and 12 hours to temperatures recorded in polyethylene terephthalate bottles in previous SODIS studies carried out under field conditions. Inclusion/exclusion of the fluorogenic vital dye propidium iodide, spontaneous excystation, and infectivity studies were used to determine the inactivation of oocysts. There was a significant increase in the percentage of oocysts that took up propidium iodide and in the number of oocysts that excysted spontaneously. There was also a significant decrease in the intensity of infection elicited in suckling mice at the end of all exposure times. The results of the study demonstrate the importance of temperature in the inactivation of C. parvum oocysts during application of SODIS under natural conditions. PMID:20064992

Altmetric: 165More detailArticle | OPENClimate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

EPA Science Inventory

Climate change is accelerating the release of dissolved organic matter (DOM) to inland and coastal waters through increases in precipitation, thawing of permafrost, and changes in vegetation. Our modeling approach suggests that the selective absorption of ultraviolet radiation (U...

No effect of femtosecond laser pulses on M13, E. coli, DNA, or protein.

PubMed

Wigle, Jeffrey C; Holwitt, Eric A; Estlack, Larry E; Noojin, Gary D; Saunders, Katharine E; Yakovlev, Valdislav V; Rockwell, Benjamin A

2014-01-01

Data showing what appears to be nonthermal inactivation of M13 bacteriophage (M13), Tobacco mosaic virus, Escherichia coli (E. coli), and Jurkatt T-cells following exposure to 80-fs pulses of laser radiation have been published. Interest in the mechanism led to attempts to reproduce the results for M13 and E. coli. Bacteriophage plaque-forming and bacteria colony-forming assays showed no inactivation of the microorganisms; therefore, model systems were used to see what, if any, damage might be occurring to biologically important molecules. Purified plasmid DNA (pUC19) and bovine serum albumin were exposed to and analyzed by agarose gel electrophoresis (AGE) and polyacrylamide gel electrophoresis (PAGE), respectively, and no effect was found. DNA and coat proteins extracted from laser-exposed M13 and analyzed by AGE or PAGE found no effect. Raman scattering by M13 in phosphate buffered saline was measured to determine if there was any physical interaction between M13 and femtosecond laser pulses, and none was found. Positive controls for the endpoints measured produced the expected results with the relevant assays. Using the published methods, we were unable to reproduce the inactivation results or to show any interaction between ultrashort laser pulses and buffer/water, DNA, protein, M13 bacteriophage, or E. coli.

No effect of femtosecond laser pulses on M13, E. coli, DNA, or protein

NASA Astrophysics Data System (ADS)

Wigle, Jeffrey C.; Holwitt, Eric A.; Estlack, Larry E.; Noojin, Gary D.; Saunders, Katharine E.; Yakovlev, Valdislav V.; Rockwell, Benjamin A.

2014-01-01

Data showing what appears to be nonthermal inactivation of M13 bacteriophage (M13), Tobacco mosaic virus, Escherichia coli (E. coli), and Jurkatt T-cells following exposure to 80-fs pulses of laser radiation have been published. Interest in the mechanism led to attempts to reproduce the results for M13 and E. coli. Bacteriophage plaque-forming and bacteria colony-forming assays showed no inactivation of the microorganisms; therefore, model systems were used to see what, if any, damage might be occurring to biologically important molecules. Purified plasmid DNA (pUC19) and bovine serum albumin were exposed to and analyzed by agarose gel electrophoresis (AGE) and polyacrylamide gel electrophoresis (PAGE), respectively, and no effect was found. DNA and coat proteins extracted from laser-exposed M13 and analyzed by AGE or PAGE found no effect. Raman scattering by M13 in phosphate buffered saline was measured to determine if there was any physical interaction between M13 and femtosecond laser pulses, and none was found. Positive controls for the endpoints measured produced the expected results with the relevant assays. Using the published methods, we were unable to reproduce the inactivation results or to show any interaction between ultrashort laser pulses and buffer/water, DNA, protein, M13 bacteriophage, or E. coli.

Visible optical radiation generates bactericidal effect applicable for inactivation of health care associated germs demonstrated by inactivation of E. coli and B. subtilis using 405-nm and 460-nm light emitting diodes

NASA Astrophysics Data System (ADS)

Hönes, Katharina; Stangl, Felix; Sift, Michael; Hessling, Martin

2015-07-01

The Ulm University of Applied Sciences is investigating a technique using visible optical radiation (405 nm and 460 nm) to inactivate health-hazardous bacteria in water. A conceivable application could be point-of-use disinfection implementations in developing countries for safe drinking water supply. Another possible application field could be to provide sterile water in medical institutions like hospitals or dental surgeries where contaminated pipework or long-term disuse often results in higher germ concentrations. Optical radiation for disinfection is presently mostly used in UV wavelength ranges but the possibility of bacterial inactivation with visible light was so far generally disregarded. One of the advantages of visible light is, that instead of mercury arc lamps, light emitting diodes could be used, which are commercially available and therefore cost-efficient concerning the visible light spectrum. Furthermore they inherit a considerable longer life span than UV-C LEDs and are non-hazardous in contrast to mercury arc lamps. Above all there are specific germs, like Bacillus subtilis, which show an inactivation resistance to UV-C wavelengths. Due to the totally different deactivation mechanism even higher disinfection rates are reached, compared to Escherichia coli as a standard laboratory germ. By 460 nm a reduction of three log-levels appeared with Bacillus subtilis and a half log-level with Escherichia coli both at a dose of about 300 J/cm². By the more efficient wavelength of 405 nm four and a half log-levels are reached with Bacillus subtilis and one and a half log-level with Escherichia coli also both at a dose of about 300 J/cm². In addition the employed optical setup, which delivered a homogeneous illumination and skirts the need of a stirring technique to compensate irregularities, was an important improvement compared to previous published setups. Evaluated by optical simulation in ZEMAX® the designed optical element provided proven homogeneity distributions with maximum variation of ± 10 %.

Inactivation of virus in intravenous immunoglobulin G using solvent/detergent treatment and pasteurization.

PubMed

Aghaie, A; Pourfatollah, A A; Bathaie, S Z; Moazzeni, S M; Khorsand Mohammad Pour, H; Sharifi, Z

2008-01-01

The safety of plasma derived medicinal products, such as immunoglobulin, depends on viral inactivation steps that are incorporated into the production process. Several attempts have been made to validate the effectiveness of these inactivation methods against a range of physio-chemically diverse viruses. Treatment with solvent/detergent (S/D) and pasteurization (P) has been continuously used in our IgG production and these methods were analysed in this study as models of viral inactivation. Bovine Viral Diarrhoea Virus (BVDV), Herpes Simplex Virus (HSV) and Vesicular Stomatitis Virus (VSV) were employed as models of HCV, HBV and HIV respectively. Polio and Reo viruses also were used as stable viruses to chemical substances. The infectivity of a range of viruses before and after treatment with two methods of viral inactivation was measured by end point titration and their effectiveness expressed as Logarithmic Reduction Factors (LRF). Solvent/detergent treatment reduced the amount of enveloped viruses by 5-6 logs. The reduction factor was between 5-6 logs for all viruses used in the pasteurization process. A final log reduction factor was obtained as the sum of the two individual methods. Both inactivation methods have advantages and disadvantages with respect to their ability to inactivate viruses. Thus,combination of two robust virus inactivation steps, solvent/detergent and pasteurization, increases the safety margin of immunoglobulin preparations.

Study of genetic effects of high energy radiations with different ionizing capacities on extracellular phages.

PubMed

Bresler, S E; Kalinin, V L; Kopylova, Y U; Krivisky, A S; Rybchin, V N; Shelegedin, V N

1975-07-01

The inactivating and mutagenic action of high-energy radiations with different ionizing capacities (gamma-rays, protons, alpha-particles and accelerated ions of 12C and 20Ne) was studied by using coliphages lambda11 and SD as subjects. In particular the role of irradiation conditions (broth suspension, pure buffer, dry samples) and of the host functions recA, exrA and polA was investigated. The dose-response curve of induced mutagenesis was studied by measuring the yield of vir mutants in lambda11 and plaque mutants in SD. The following results were obtained. (1) The inactivation kinetics of phages under the action of gamma-rays and protons was first order to a survival of 10(-7). Heavy ions also showed exponential inactivation kinetics to a survival of 10(-4). At higher doses of 20Ne ion bombardment some deviation from one-hit kinetics was observed. For dry samples of phages the dimensions of targets for all types of radiation were approximately proportional to the molecular weights of phage DNA's. For densely ionizing radiation (heavy ions) the inactivating action was 3-5 times weaker than for gamma-rays and protons. (2) Mutagenesis was observed for all types of radiation, but heavy ions were 1-5-2 times less efficient than gamma-rays. For both phages studied the dose-response curve of mutagenesis was non-linear. The dependence on the dose was near to parabolic for lambda11. For SD a plateau or maximum of mutagenesis was observed for the relative number of mutants at a survival of about 10(-4). (3) Host-cell functions recA and exrA were practically indifferent for survival of gamma-irradiated phage lambda11, but indispensable for mutagenesis. Mutation recAI3 abolished induced vir mutations totally and exrA- reduced them significantly. The absence of the function polA had a considerable influence on phage survival, but no effect on vir mutation yield (if compared at the same survival level). (4) In conditions of indirect action of gamma-rays no vir mutations were induced. This is regarded as evidence that the single-strand breaks formed under indirect action conditions cannot serve as pre-mutational damage in DNA.

Impacts of Goethite Particles on UV Disinfection of Drinking Water

PubMed Central

Wu, Youxian; Clevenger, Thomas; Deng, Baolin

2005-01-01

A unique association between bacterial cells and small goethite particles (∼0.2 by 2 μm) protected Escherichia coli and Pseudomonas putida from UV inactivation. The protection increased with the particle concentration in the turbidity range of 1 to 50 nephelometric turbidity units and with the bacterium-particle attachment time prior to UV irradiation. The lower degree of bacterial inactivation at longer attachment time was mostly attributed to the particle aggregation surrounding bacteria that provided shielding from UV radiation. PMID:16000835

Inactivation of ascaris lumbricoides eggs by heat, radiation, and thermoradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brannen, J. P.; Garst, D. M.; Langley, S.

1975-07-01

It is desirable to eliminate the public health hazards associated with land application of municipal sewage sludge as a fertilizer or soil conditioner. This report describes experimentation to determine the effects of heat, radiation, and thermoradiation on the suppression of embryonation of Ascaris lumbricoides ova, a parasite commonly found in sewage sludge. Heat effects were observed at a minimum temperature of 51°C and radiation effects at doses in excess of 15 krads of ionizing gamma radiation. Thermoradiation at 47°C suppressed embryonation at less than half the total dose required by radiation alone.

DNA aptamer functionalized gold nanostructures for molecular recognition and photothermal inactivation of methicillin-Resistant Staphylococcus aureus.

PubMed

Ocsoy, Ismail; Yusufbeyoglu, Sadi; Yılmaz, Vedat; McLamore, Eric S; Ildız, Nilay; Ülgen, Ahmet

2017-11-01

In this work, we report the development of DNA aptamer-functionalized gold nanoparticles (Apt@Au NPs) and gold nanorods (Apt@Au NRs) for inactivation of Methicillin-resistant Staphylococcus aureus (MRSA) with targeted photothermal therapy (PTT). Although both Apt@Au NPs and Apt@Au NRs specifically bind to MRSA cells, Apt@Au NPs and Apt@Au NRs inactivated ∼5% and over 95% of the cells,respectively through PTT. This difference in inactivation was based on the relatively high longitudinal absorption of near-infrared (NIR) radiation and strong photothermal conversion capability for the Apt@Au NRs compared to the Apt@Au NPs. The Au NRs served as a nanoplatform for the loading of thiolated aptamer and also provided multivalent effects for increasing binding strength and affinity to MRSA. Our results indicate that the type of aptamer and the degree of multivalent effect(s) are important factors for MRSA inactivation efficiency in PTT. We show that the Apt@Au NRs are a very effective and promising nanosystem for specific cell recognition and in vitro PTT. Copyright © 2017 Elsevier B.V. All rights reserved.

Inactivation of kupffer cells by gadolinium chloride protects murine liver from radiation-induced apoptosis.

PubMed

Du, Shi-Suo; Qiang, Min; Zeng, Zhao-Chong; Ke, Ai-Wu; Ji, Yuan; Zhang, Zheng-Yu; Zeng, Hai-Ying; Liu, Zhongshan

2010-03-15

To determine whether the inhibition of Kupffer cells before radiotherapy (RT) would protect hepatocytes from radiation-induced apoptosis. A single 30-Gy fraction was administered to the upper abdomen of Sprague-Dawley rats. The Kupffer cell inhibitor gadolinium chloride (GdCl3; 10 mg/kg body weight) was intravenously injected 24 h before RT. The rats were divided into four groups: group 1, sham RT plus saline (control group); group 2, sham RT plus GdCl3; group 3, RT plus saline; and group 4, RT plus GdCl3. Liver tissue was collected for measurement of apoptotic cytokine expression and evaluation of radiation-induced liver toxicity by analysis of liver enzyme activities, hepatocyte micronucleus formation, apoptosis, and histologic staining. The expression of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha was significantly attenuated in group 4 compared with group 3 at 2, 6, 24, and 48 h after injection (p <0.05). At early points after RT, the rats in group 4 exhibited significantly lower levels of liver enzyme activity, apoptotic response, and hepatocyte micronucleus formation compared with those in group 3. Selective inactivation of Kupffer cells with GdCl3 reduced radiation-induced cytokine production and protected the liver against acute radiation-induced damage. Copyright 2010 Elsevier Inc. All rights reserved.

Biological effects of high ultraviolet radiation on early earth--a theoretical evaluation.

PubMed

Cockell, C S

1998-08-21

The surface of early Earth was exposed to both UVC radiation (< 280 nm) and higher doses of UVB (280-315 nm) compared with the surface of present day Earth. The degree to which this radiation environment acted as a selection pressure on organisms and biological systems has rarely been theoretically examined with respect to the biologically effective irradiances that ancient organisms would receive. Here action spectra for DNA inactivation and isolated chloroplast inhibition are used to estimate biologically effective irradiances on archean Earth. Comparisons are made with present day Earth. The theoretical estimations on the UV radiation screening required to protect DNA on archean Earth compare well with field and laboratory observations on protection strategies found in present day microbial communities. They suggest that many physical and biological methods may have been effective and would have allowed for the radiation of life even under the high UV radiation regimes of archean Earth. Such strategies would also have provided effective reduction of photoinhibition by UV radiation. The data also suggest that the UV regime on the surface of Mars is not a life limiting factor per se, although other environmental factors such as desiccation and low temperatures may contribute towards the apparent lack of a surface biota.

Bacteria and fungi inactivation by photocatalysis under UVA irradiation: liquid and gas phase.

PubMed

Rodrigues-Silva, Caio; Miranda, Sandra M; Lopes, Filipe V S; Silva, Mário; Dezotti, Márcia; Silva, Adrián M T; Faria, Joaquim L; Boaventura, Rui A R; Vilar, Vítor J P; Pinto, Eugénia

2017-03-01

In the last decade, environmental risks associated with wastewater treatment plants (WWTPs) have become a concern in the scientific community due to the absence of specific legislation governing the occupational exposure limits (OEL) for microorganisms present in indoor air. Thus, it is necessary to develop techniques to effectively inactivate microorganisms present in the air of WWTPs facilities. In the present work, ultraviolet light A radiation was used as inactivation tool. The microbial population was not visibly reduced in the bioaerosol by ultraviolet light A (UVA) photolysis. The UVA photocatalytic process for the inactivation of microorganisms (bacteria and fungi, ATCC strains and isolates from indoor air samples of a WWTP) using titanium dioxide (TiO 2 P25) and zinc oxide (ZnO) was tested in both liquid-phase and airborne conditions. In the slurry conditions at liquid phase, P25 showed a better performance in inactivation. For this reason, gas-phase assays were performed in a tubular photoreactor packed with cellulose acetate monolithic structures coated with P25. The survival rate of microorganisms under study decreased with the catalyst load and the UVA exposure time. Inactivation of fungi was slower than resistant bacteria, followed by Gram-positive bacteria and Gram-negative bacteria. Graphical abstract Inactivation of fungi and bacteria in gas phase by photocatalitic process performed in a tubular photoreactor packed with cellulose acetate monolith structures coated with TiO 2 .

Inactivation of uropathogenic Escherichia coli in ground chicken meat using high pressure processing and gamma radiation, and in purge and chicken meat surfaces by ultraviolet light

USDA-ARS?s Scientific Manuscript database

Uropathogenic Escherichia coli (UPEC) are common contaminants in meat and poultry. Nonthermal food safety intervention technologies used to improve safety and shelf-life of both human and pet foods can include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV...

Rapid Bedside Inactivation of Ebola Virus for Safe Nucleic Acid Tests.

PubMed

Rosenstierne, Maiken Worsøe; Karlberg, Helen; Bragstad, Karoline; Lindegren, Gunnel; Stoltz, Malin Lundahl; Salata, Cristiano; Kran, Anne-Marte Bakken; Dudman, Susanne Gjeruldsen; Mirazimi, Ali; Fomsgaard, Anders

2016-10-01

Rapid bedside inactivation of Ebola virus would be a solution for the safety of medical and technical staff, risk containment, sample transport, and high-throughput or rapid diagnostic testing during an outbreak. We show that the commercially available Magna Pure lysis/binding buffer used for nucleic acid extraction inactivates Ebola virus. A rapid bedside inactivation method for nucleic acid tests is obtained by simply adding Magna Pure lysis/binding buffer directly into vacuum blood collection EDTA tubes using a thin needle and syringe prior to sampling. The ready-to-use inactivation vacuum tubes are stable for more than 4 months, and Ebola virus RNA is preserved in the Magna Pure lysis/binding buffer for at least 5 weeks independent of the storage temperature. We also show that Ebola virus RNA can be manually extracted from Magna Pure lysis/binding buffer-inactivated samples using the QIAamp viral RNA minikit. We present an easy and convenient method for bedside inactivation using available blood collection vacuum tubes and reagents. We propose to use this simple method for fast, safe, and easy bedside inactivation of Ebola virus for safe transport and routine nucleic acid detection. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

On a fundamental problem in radiation biology

NASA Technical Reports Server (NTRS)

Dugan, V.; Trujillo, R.

1974-01-01

Experimental evidence indicates that the radiation dose required to reduce a surviving population to a certain fraction of its original population is lower for vertebrate cells than for viruses. On the other hand, the number of ionizations per cell required to inactivate that cell is greater for vertebrate cells than for viruses. The apparent conflict between these two findings is investigated. It is found that the apparent contradiction is probably a result of the fractional power dependence of the radiation-dose value on the nucleic acid weight.

Modeling-independent elucidation of inactivation pathways in recombinant and native A-type Kv channels.

PubMed

Fineberg, Jeffrey D; Ritter, David M; Covarrubias, Manuel

2012-11-01

A-type voltage-gated K(+) (Kv) channels self-regulate their activity by inactivating directly from the open state (open-state inactivation [OSI]) or by inactivating before they open (closed-state inactivation [CSI]). To determine the inactivation pathways, it is often necessary to apply several pulse protocols, pore blockers, single-channel recording, and kinetic modeling. However, intrinsic hurdles may preclude the standardized application of these methods. Here, we implemented a simple method inspired by earlier studies of Na(+) channels to analyze macroscopic inactivation and conclusively deduce the pathways of inactivation of recombinant and native A-type Kv channels. We investigated two distinct A-type Kv channels expressed heterologously (Kv3.4 and Kv4.2 with accessory subunits) and their native counterparts in dorsal root ganglion and cerebellar granule neurons. This approach applies two conventional pulse protocols to examine inactivation induced by (a) a simple step (single-pulse inactivation) and (b) a conditioning step (double-pulse inactivation). Consistent with OSI, the rate of Kv3.4 inactivation (i.e., the negative first derivative of double-pulse inactivation) precisely superimposes on the profile of the Kv3.4 current evoked by a single pulse because the channels must open to inactivate. In contrast, the rate of Kv4.2 inactivation is asynchronous, already changing at earlier times relative to the profile of the Kv4.2 current evoked by a single pulse. Thus, Kv4.2 inactivation occurs uncoupled from channel opening, indicating CSI. Furthermore, the inactivation time constant versus voltage relation of Kv3.4 decreases monotonically with depolarization and levels off, whereas that of Kv4.2 exhibits a J-shape profile. We also manipulated the inactivation phenotype by changing the subunit composition and show how CSI and CSI combined with OSI might affect spiking properties in a full computational model of the hippocampal CA1 neuron. This work unambiguously elucidates contrasting inactivation pathways in neuronal A-type Kv channels and demonstrates how distinct pathways might impact neurophysiological activity.

A biotechnological project with a gamma radiation source of 100,000 Ci

NASA Astrophysics Data System (ADS)

Lombardo, J. H.; Smolko, E. E.

A project for the production of radiovaccines and other bio-medical products is presented which includes a radiation facility provided with a gamma ray source equivalent to 100,000 Ci of Co-60. The whole process incorporates novel basic features in virus production and inactivation steps. The former is carried out in animals previously subjected to immunodepression through electromagnetic radiation. The later is obtained at low temperatures by using either electromagnetic or particle radiations. A vaccine manufacture process is shown to illustrate the utilization of ionizing radiations to obtain a foot and mouth disease virus (FMDV) vaccine with good antigenic quality and low cost.

Effect of iron salt counter ion in dose-response curves for inactivation of Fusarium solani in water through solar driven Fenton-like processes

NASA Astrophysics Data System (ADS)

Aurioles-López, Verónica; Polo-López, M. Inmaculada; Fernández-Ibáñez, Pilar; López-Malo, Aurelio; Bandala, Erick R.

2016-02-01

The inactivation of Fusarium solani in water was assessed by solar driven Fenton-like processes using three different iron salts: ferric acetylacetonate (Fe(acac)3), ferric chloride (FeCl3) and ferrous sulfate (FeSO4). The experimental conditions tested were [Fe] ≈ 5 mg L-1, [H2O2] ≈ 10 mg L-1 and [Fe] ≈ 10 mg L-1; [H2O2] ≈ 20 mg L-1 mild and high, respectively, and pH 3.0 and 5.0, under solar radiation. The highest inactivation rates were observed at high reaction conditions for the three iron salts tested at pH 5.0 with less than 3.0 kJ L-1 of accumulate energy (QUV) to achieve over 99.9% of F. solani inactivation. Fe(acac)3 was the best iron salt to accomplishing F. solani inactivation. The modified Fermi equation was used to fix the experimental inactivation, data showed it was helpful for modeling the process, adequately describing dose-response curves. Inactivation process using FeSO4 at pH 3.0 was modeled fairly with r2 = 0.98 and 0.99 (mild and high concentration, respectively). Fe(acac)3, FeCl3 and FeSO4 at high concentration (i.e. [Fe] ≈ 10 mg L-1; [H2O2] ≈ 20 mg L-1) and pH 5.0 showed the highest fitting values (r2 = 0.99). Iron salt type showed a remarkable influence on the Fenton-like inactivation process.

Mycobacteria inactivation using Engineered Water Nanostructures (EWNS).

PubMed

Pyrgiotakis, Georgios; McDevitt, James; Gao, Ya; Branco, Alan; Eleftheriadou, Mary; Lemos, Bernardo; Nardell, Edward; Demokritou, Philip

2014-08-01

Airborne transmitted pathogens such as Mycobacterium tuberculosis (Mtb) cause serious, often fatal infectious disease with enormous global health implications. Due to their unique cell wall and slow growth, mycobacteria are among the most resilient microbial forms. Herein we evaluate the ability of an emerging, chemical-free, nanotechnology-based method to inactivate M. parafortuitum (Mtb surrogate). This method is based on the transformation of atmospheric water vapor into engineered water nano-structures (EWNS) via electrospray. We demonstrate that the EWNS can interact with and inactivate airborne mycobacteria, reducing their concentration levels significantly. Additionally, EWNS can inactivate M. parafortuitum on surfaces eight times faster than the control. The mechanism of mycobacteria inactivation was also investigated in this study. It was demonstrated that the EWNS effectively deliver the reactive oxygen species, encapsulated during the electrospray process, to the bacteria oxidizing their cell membrane resulting into inactivation. Overall, this is a method with the potential to become an effective intervention technology in the battle against airborne infections. This study demonstrates the feasibility of mycobacterium inactivation in airborne form or on contact surfaces using electrospray activated water nano-structures. Given that the method is free of toxic chemicals, this might become an important tool in the prevention of mycobacterial infections, which are notoriously hard to treat. Copyright © 2014 Elsevier Inc. All rights reserved.

[Development and validation of an analytical method to quantify residues of cleaning products able to inactivate prion].

PubMed

Briot, T; Robelet, A; Morin, N; Riou, J; Lelièvre, B; Lebelle-Dehaut, A-V

2016-07-01

In this study, a novel analytical method to quantify prion inactivating detergent in rinsing waters coming from the washer-disinfector of a hospital sterilization unit has been developed. The final aim was to obtain an easy and functional method in a routine hospital process which does not need the cleaning product manufacturer services. An ICP-MS method based on the potassium dosage of the washer-disinfector's rinsing waters was developed. Potassium hydroxide is present on the composition of the three prion inactivating detergent currently on the French market. The detergent used in this study was the Actanios LDI(®) (Anios laboratories). A Passing and Bablok regression compares concentrations measured with this developed method and with the HPLC-UV manufacturer method. According to results obtained, the developed method is easy to use in a routine hospital process. The Passing and Bablok regression showed that there is no statistical difference between the two analytical methods during the second rinsing step. Besides, both methods were linear on the third rinsing step, with a 1.5ppm difference between the concentrations measured for each method. This study shows that the ICP-MS method developed is nonspecific for the detergent, but specific for the potassium element which is present in all prion inactivating detergent currently on the French market. This method should be functional for all the prion inactivating detergent containing potassium, if the sensibility of the method is sufficient when the potassium concentration is very low in the prion inactivating detergent formulation. Copyright © 2016. Published by Elsevier Masson SAS.

Chlorophyll mediated photodynamic inactivation of blue laser on Streptococcus mutans

NASA Astrophysics Data System (ADS)

Astuti, Suryani Dyah; Zaidan, A.; Setiawati, Ernie Maduratna; Suhariningsih

2016-03-01

Photodynamic inactivation is an inactivation method in microbial pathogens that utilize light and photosensitizer. This study was conducted to investigate photodynamic inactivation effects of low intensity laser exposure with various dose energy on Streptococcus mutans bacteria. The photodynamic inactivation was achieved with the addition of chlorophyll as photosensitizers. To determine the survival percentage of Streptococcus mutans bacteria after laser exposure, the total plate count method was used. For this study, the wavelength of the laser is 405 nm and variables of energy doses are 1.44, 2.87, 4.31, 5.74, 7.18, and 8.61 in J/cm2. The results show that exposure to laser with energy dose of 7.18 J/cm2 has the best photodynamic inactivation with a decrease of 78% in Streptococcus

Pretreatment to avoid positive RT-PCR results with inactivated viruses.

PubMed

Nuanualsuwan, Suphachai; Cliver, Dean O

2002-07-01

Enteric viruses that are important causes of human disease must often be detected by reverse transcription-polymerase chain reaction (RT-PCR), a method that commonly yields positive results with samples that contain only inactivated virus. This study was intended to develop a pretreatment for samples, so that inactivated viruses would not be detected by the RT-PCR procedure. Model viruses were human hepatitis A virus, vaccine poliovirus 1 and feline calicivirus as a surrogate for the Norwalk-like viruses. Each virus was inactivated (from an initial titer of approximately 10(3) PFU/ml) by ultraviolet light, hypochlorite or heating at 72 degrees C. Inactivated viruses, that were treated with proteinase K and ribonuclease for 30 min at 37 degrees C before RT-PCR, gave a negative result, which is to say that no amplicon was detected after the reaction was completed. This antecedent to the RT-PCR method may be applicable to other types of viruses, to viruses inactivated in other ways and to other molecular methods of virus detection.

Effective Chemical Inactivation of Ebola Virus

PubMed Central

Haddock, Elaine; Feldmann, Friederike

2016-01-01

Reliable inactivation of specimens before removal from high-level biocontainment is crucial for safe operation. To evaluate efficacy of methods of chemical inactivation, we compared in vitro and in vivo approaches using Ebola virus as a surrogate pathogen. Consequently, we have established parameters and protocols leading to reliable and effective inactivation. PMID:27070504

Space Radiation and its Associated Health Consequences

NASA Technical Reports Server (NTRS)

Wu, Honglu

2007-01-01

During space travel, astronauts are exposed to energetic particles of a complex composition and energy distribution. For the same amount of absorbed dose, these particles can be much more effective than X- or gamma rays in the induction of biological effects, including cell inactivation, genetic mutations, cataracts, and cancer induction. Several of the biological consequences of space radiation exposure have already been observed in astronauts. This presentation will introduce the space radiation environment and discuss its associated health risks. Accurate assessment of the radiation risks and development of respective countermeasures are essential for the success of future exploration missions to the Moon and Mars.

Origin and evolution of the long non-coding genes in the X-inactivation center.

PubMed

Romito, Antonio; Rougeulle, Claire

2011-11-01

Random X chromosome inactivation (XCI), the eutherian mechanism of X-linked gene dosage compensation, is controlled by a cis-acting locus termed the X-inactivation center (Xic). One of the striking features that characterize the Xic landscape is the abundance of loci transcribing non-coding RNAs (ncRNAs), including Xist, the master regulator of the inactivation process. Recent comparative genomic analyses have depicted the evolutionary scenario behind the origin of the X-inactivation center, revealing that this locus evolved from a region harboring protein-coding genes. During mammalian radiation, this ancestral protein-coding region was disrupted in the marsupial group, whilst it provided in eutherian lineage the starting material for the non-translated RNAs of the X-inactivation center. The emergence of non-coding genes occurred by a dual mechanism involving loss of protein-coding function of the pre-existing genes and integration of different classes of mobile elements, some of which modeled the structure and sequence of the non-coding genes in a species-specific manner. The rising genes started to produce transcripts that acquired function in regulating the epigenetic status of the X chromosome, as shown for Xist, its antisense Tsix, Jpx, and recently suggested for Ftx. Thus, the appearance of the Xic, which occurred after the divergence between eutherians and marsupials, was the basis for the evolution of random X inactivation as a strategy to achieve dosage compensation. Copyright © 2011. Published by Elsevier Masson SAS.

Cell inactivation, repair and mutation induction in bacteria after heavy ion exposure: results from experiments at accelerators and in space.

PubMed

Horneck, G; Schafer, M; Baltschukat, K; Weisbrod, U; Micke, U; Facius, R; Bucker, H

1989-01-01

To understand the mechanisms of accelerated heavy ions on biological matter, the responses of spores of B. subtilis to this structured high LET radiation was investigated applying two different approaches. 1) By the use of the Biostack concept, the inactivation probability as a function of radial distance to single particles' trajectory (i.e. impact parameter) was determined in space experiments as well as at accelerators using low fluences of heavy ions. It was found that spores can survive even a central hit and that the effective range of inactivation extends far beyond impact parameters where inactivation by delta-ray dose would be effective. Concerning the space experiment, the inactivation cross section exceeds those from comparable accelerator experiments by roughly a factor of 20. 2) From fluence effect curves, cross sections for inactivation and mutation induction, and the efficiency of repair processes were determined. They are influenced by the ions characteristics in a complex manner. According to dependence on LET, at least 3 LET ranges can be differentiated: A low LET range (app. < 200 keV/micrometers), where cross sections for inactivation and mutation induction follow a common curve for different ions and where repair processes are effective; an intermediate LET range of the so-called saturation cross section with negligible mutagenic and repair efficiency; and a high LET range (>1000 keV/micrometers) where the biological endpoints are majorly dependent on atomic mass and energy of the ion under consideration.

Radiation-Dependent Limit for the Viability of Bacterial Spores in Halite Fluid Inclusions and on Mars

NASA Technical Reports Server (NTRS)

Kminek, Gerhard; Bada, Jeffrey L.; Pogliano, Kit; Ward, John F.

2003-01-01

When claims for the long-term survival of viable organisms are made, either within terrestrial minerals or on Mars, considerations should be made of the limitations imposed by the naturally occurring radiation dose to which they have been exposed. We investigated the effect of ionizing radiation on different bacterial spores by measuring the inactivation constants for B. subtilis and s. marismortui spores in solution as well as for dry spores of B. subtilis and B. thuringiensis. S. marismortui is a halophilic spore that is genetically similar to the recently discovered 2-9-3 bacterium from a halite fluid inclusion, claimed to be 250 million years old, B. thuringiensis is a soil bacterium that is genetically similar to the human pathogens B. anthracis and B. cereus. To relate the inactivation constant to some realistic environments, we calculated the radiation regimen in a halite fluid inclusion and in the Martian subsurface over time. Our conclusion is that the ionizing dose of radiation in those environments limits the survival of viable bacterial spores over long periods. In the absence of an active repair mechanism in the dormant state, the long-term survival of spores is limited to less than 109 million years in halite fluid inclusions, to 100 to 160 million years in the Martian subsurface below 3 m, and to less than 600,000 years in the upper-most meter of Mars.

VUV absorption spectroscopy of bacterial spores and DNA components

NASA Astrophysics Data System (ADS)

Fiebrandt, Marcel; Lackmann, Jan-Wilm; Raguse, Marina; Moeller, Ralf; Awakowicz, Peter; Stapelmann, Katharina

2017-01-01

Low-pressure plasmas can be used to inactivate bacterial spores and sterilize goods for medical and pharmaceutical applications. A crucial factor are damages induced by UV and VUV radiation emitted by the plasma. To analyze inactivation processes and protection strategies of spores, absorption spectra of two B. subtilis strains are measured. The results indicate, that the inner and outer coat of the spore significantly contribute to the absorption of UV-C and also of the VUV, protecting the spore against radiation based damages. As the sample preparation can significantly influence the absorption spectra due to salt residues, the cleaning procedure and sample deposition is tested for its reproducibility by measuring DNA oligomers and pUC18 plasmid DNA. The measurements are compared and discussed with results from the literature, showing a strong decrease of the salt content enabling the detection of absorption structures in the samples.

A comparative study of disinfection efficiency and regrowth control of microorganism in secondary wastewater effluent using UV, ozone, and ionizing irradiation process.

PubMed

Lee, O-Mi; Kim, Hyun Young; Park, Wooshin; Kim, Tae-Hun; Yu, Seungho

2015-09-15

Ionizing radiation technology was suggested as an alternative method to disinfection processes, such as chlorine, UV, and ozone. Although many studies have demonstrated the effectiveness of irradiation technology for microbial disinfection, there has been a lack of information on comparison studies of disinfection techniques and a regrowth of each treatment. In the present study, an ionizing radiation was investigated to inactivate microorganisms and to determine the critical dose to prevent the regrowth. As a result, it was observed that the disinfection efficiency using ionizing radiation was not affected by the seasonal changes of wastewater characteristics, such as temperature and turbidity. In terms of bacterial regrowth after disinfection, the ionizing radiation showed a significant resistance of regrowth, whereas, on-site UV treatment is influenced by the suspended solid, temperature, or precipitation. The electric power consumption was also compared for the economic feasibility of each technique at a given value of disinfection efficiency of 90% (1-log), showing 0.12, 36.80, and 96.53 Wh/(L/day) for ionizing radiation, ozone, and UV, respectively. The ionizing radiation requires two or three orders of magnitude lower power consumption than UV and ozone. Consequently, ionizing radiation can be applied as an effective and economical alternative technique to other conventional disinfection processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Spontaneous and radiation-induced genomic instability in human cell lines differing in cellular TP53 status.

PubMed

Moore, Stephen R; Ritter, Linda E; Gibbons, Catherine F; Grosovsky, Andrew J

2005-10-01

Structural chromosomal rearrangements are commonly observed in tumor karyotypes and in radiation-induced genomic instability. Here we report the effects of TP53 deficiency on karyotypic stability before and after irradiation using related cells and clones differing in cellular TP53 status. The parental cell line, TK6, is a TP53 wild-type human B-lymphoblastoid line with a highly stable karyotype. In the two TK6 derivatives used here, TP53 has been inactivated by biochemical means (expression of HPV16 E6; TK6-5E) or genetic means (allelic inactivation; NH32). Biochemical inactivation of TP53 (TK6-5E) had little effect on the spontaneous karyotype, whereas allelic inactivation of TP53 (NH32) resulted in a modest increase in spontaneous karyotypic instability. After 2 Gy gamma irradiation, the number of unstable clones derived from TP53-deficient cells was significantly elevated compared to the TP53 wild-type counterpart. Extensively destabilized clones were common after irradiation in the set of clones derived from NH32 cells, and one was observed in the set of TK6-5E clones; however, they were never observed in TK6-derived clones. In two of the irradiated NH32 clones, whole chromosomes or chromosome bands were preferentially involved in alterations. These results suggest that genomic instability may differ both quantitatively and qualitatively as a consequence of altered TP53 expression. Some of the results showing repeated and preferential chromosome involvement in aberrations support a model in which instability may be driven by cis mechanisms.

Inactivation of chemical and heat-resistant spores of Bacillus and Geobacillus by nitrogen cold atmospheric plasma evokes distinct changes in morphology and integrity of spores.

PubMed

van Bokhorst-van de Veen, Hermien; Xie, Houyu; Esveld, Erik; Abee, Tjakko; Mastwijk, Hennie; Nierop Groot, Masja

2015-02-01

Bacterial spores are resistant to severe conditions and form a challenge to eradicate from food or food packaging material. Cold atmospheric plasma (CAP) treatment is receiving more attention as potential sterilization method at relatively mild conditions but the exact mechanism of inactivation is still not fully understood. In this study, the biocidal effect by nitrogen CAP was determined for chemical (hypochlorite and hydrogen peroxide), physical (UV) and heat-resistant spores. The three different sporeformers used are Bacillus cereus a food-borne pathogen, and Bacillus atrophaeus and Geobacillus stearothermophilus that are used as biological indicators for validation of chemical sterilization and thermal processes, respectively. The different spores showed variation in their degree of inactivation by applied heat, hypochlorite, hydrogen peroxide, and UV treatments, whereas similar inactivation results were obtained with the different spores treated with nitrogen CAP. G. stearothermophilus spores displayed high resistance to heat, hypochlorite, hydrogen peroxide, while for UV treatment B. atrophaeus spores are most tolerant. Scanning electron microscopy analysis revealed distinct morphological changes for nitrogen CAP-treated B. cereus spores including etching effects and the appearance of rough spore surfaces, whereas morphology of spores treated with heat or disinfectants showed no such changes. Moreover, microscopy analysis revealed CAP-exposed B. cereus spores to turn phase grey conceivably because of water influx indicating damage of the spores, a phenomenon that was not observed for non-treated spores. In addition, data are supplied that exclude UV radiation as determinant of antimicrobial activity of nitrogen CAP. Overall, this study shows that nitrogen CAP treatment has a biocidal effect on selected Bacillus and Geobacillus spores associated with alterations in spore surface morphology and loss of spore integrity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Radiological health risks for exploratory class missions in space

NASA Technical Reports Server (NTRS)

Nachtwey, D. Stuart; Yang, Tracy Chui-Hsu

1991-01-01

The radiation risks to crewmembers on missions to the moon and Mars are studied. A graph is presented of the cross section as a function of linear energy transfer (LET) for cell inactivation and neoplastic cell transformation. Alternatives to conventional approaches to radiation protection using dose and Q are presented with attention given to a hybrid of the conventional system for particles with LET less than 100 keV/micron.

Inactivation of the Radiation-Resistant Spoilage Bacterium Micrococcus radiodurans

PubMed Central

Duggan, D. E.; Anderson, A. W.; Elliker, P. R.

1963-01-01

A simplified technique permitting the pipetting of raw puréed meats for quantitative bacteriological study is described for use in determining survival of these non-sporing bacteria, which are exceptionally resistant to radiation. Survival curves, using gamma radiation as the sterilizing agent, were determined in raw beef with four strains of Micrococcus radiodurans. Survival curves of the R1 strain in other meat substrates showed that survival was significantly greater in raw beef and raw chicken than in raw fish or in cooked beef. Resistance was lowest in the buffer. Cells grown in broth (an artificial growth medium) and resuspended in beef did not differ in resistance from cells that had been grown and irradiated in beef. Survival rate was statistically independent of the initial cell concentration, even though there appeared to be a correlation between lower death rate and lower initial cell concentrations. The initial viable count of this culture of the domesticated R1 strain in beef was reduced by a factor of about 10-5 by 3.0 megarad, and 4.0 megarad reduced the initial count by a factor of more than 10-9. Data suggest that M. radiodurans R1 is more resistant to radiation than spore-forming spoilage bacteria for which inactivation rates have been published. PMID:14063780

Solar disinfection: an approach for low-cost household water treatment technology in Southwestern Ethiopia.

PubMed

Dessie, Awrajaw; Alemayehu, Esayas; Mekonen, Seblework; Legesse, Worku; Kloos, Helmut; Ambelu, Argaw

2014-01-10

Disinfection of contaminated water using solar radiation (SODIS) is known to inactivate bacteria. Its inactivation efficiency depends on local conditions where the disinfection is made. This study was aiming to test the efficiency of solar disinfection using different water parameters as low-cost household water treatment technology. Inactivation of microbes was tested using fecal coliform as test organism. The SODIS experiment was carried out at turbidity 2NTU, pH 7, and various water temperature (38.1°C, 41.8°C, 45.6°Cand 51.1°C) and solar intensities, using clear and black plastic bottles filled to different depths. The results show that the rate of microbial inactivation in relation to depth of water, turbidity, container type, intensity of light and color of container was statistically significant (p < 0.05). However, bottle placement, exposure and water pH were unrelated to microbial inactivation. Bacterial re-growth was not observed after solar disinfection. By adjusting the parameters, complete and irreversible fecal coliform inactivation was achieved within an exposure time of less than four hours in the areas where the solar irradiance is about 3.99 kW/m2 and above. Our results indicate that application of SODIS could play a significant role in the provision of safe water in rural communities of developing countries where there is ample sunshine, specifically in sub-Saharan African countries.

Solar disinfection: an approach for low-cost household water treatment technology in Southwestern Ethiopia

PubMed Central

2014-01-01

Disinfection of contaminated water using solar radiation (SODIS) is known to inactivate bacteria. Its inactivation efficiency depends on local conditions where the disinfection is made. This study was aiming to test the efficiency of solar disinfection using different water parameters as low-cost household water treatment technology. Inactivation of microbes was tested using fecal coliform as test organism. The SODIS experiment was carried out at turbidity 2NTU, pH 7, and various water temperature (38.1°C, 41.8°C, 45.6°Cand 51.1°C) and solar intensities, using clear and black plastic bottles filled to different depths. The results show that the rate of microbial inactivation in relation to depth of water, turbidity, container type, intensity of light and color of container was statistically significant (p < 0.05). However, bottle placement, exposure and water pH were unrelated to microbial inactivation. Bacterial re-growth was not observed after solar disinfection. By adjusting the parameters, complete and irreversible fecal coliform inactivation was achieved within an exposure time of less than four hours in the areas where the solar irradiance is about 3.99 kW/m2 and above. Our results indicate that application of SODIS could play a significant role in the provision of safe water in rural communities of developing countries where there is ample sunshine, specifically in sub-Saharan African countries. PMID:24410979

[Methods of testing inactivated antirabies vaccines].

PubMed

Nedosekov, V V; Vishniakov, I F; Gruzdev, K N

2001-01-01

Methods for evaluating the potency of inactivated rabies vaccines are reviewed. Shortcomings of the traditional NIH method and advantages of modern rapid immunological in vitro methods (antibody binding test, radial immunodiffusion test, enzyme linked immunoadsorbent assay) for estimation of antigenic activity of vaccines are discussed.

Modeling-independent elucidation of inactivation pathways in recombinant and native A-type Kv channels

PubMed Central

Fineberg, Jeffrey D.; Ritter, David M.

2012-01-01

A-type voltage-gated K+ (Kv) channels self-regulate their activity by inactivating directly from the open state (open-state inactivation [OSI]) or by inactivating before they open (closed-state inactivation [CSI]). To determine the inactivation pathways, it is often necessary to apply several pulse protocols, pore blockers, single-channel recording, and kinetic modeling. However, intrinsic hurdles may preclude the standardized application of these methods. Here, we implemented a simple method inspired by earlier studies of Na+ channels to analyze macroscopic inactivation and conclusively deduce the pathways of inactivation of recombinant and native A-type Kv channels. We investigated two distinct A-type Kv channels expressed heterologously (Kv3.4 and Kv4.2 with accessory subunits) and their native counterparts in dorsal root ganglion and cerebellar granule neurons. This approach applies two conventional pulse protocols to examine inactivation induced by (a) a simple step (single-pulse inactivation) and (b) a conditioning step (double-pulse inactivation). Consistent with OSI, the rate of Kv3.4 inactivation (i.e., the negative first derivative of double-pulse inactivation) precisely superimposes on the profile of the Kv3.4 current evoked by a single pulse because the channels must open to inactivate. In contrast, the rate of Kv4.2 inactivation is asynchronous, already changing at earlier times relative to the profile of the Kv4.2 current evoked by a single pulse. Thus, Kv4.2 inactivation occurs uncoupled from channel opening, indicating CSI. Furthermore, the inactivation time constant versus voltage relation of Kv3.4 decreases monotonically with depolarization and levels off, whereas that of Kv4.2 exhibits a J-shape profile. We also manipulated the inactivation phenotype by changing the subunit composition and show how CSI and CSI combined with OSI might affect spiking properties in a full computational model of the hippocampal CA1 neuron. This work unambiguously elucidates contrasting inactivation pathways in neuronal A-type Kv channels and demonstrates how distinct pathways might impact neurophysiological activity. PMID:23109714

Effectiveness of irradiation treatments in inactivating Listeria monocytogenes on fresh vegetables at refrigeration temperature.

PubMed

Bari, M L; Nakauma, M; Todoriki, S; Juneja, Vijay K; Isshiki, K; Kawamoto, S

2005-02-01

Ionizing radiation can be effective in controlling the growth of food spoilage and foodborne pathogenic bacteria. This study reports on an investigation of the effectiveness of irradiation treatment to eliminate Listeria monocytogenes on laboratory-inoculated broccoli, cabbage, tomatoes, and mung bean sprouts. Irradiation of broccoli and mung bean sprouts at 1.0 kGy resulted in reductions of approximately 4.88 and 4.57 log CFU/g, respectively, of a five-strain cocktail of L. monocytogenes. Reductions of approximately 5.25 and 4.14 log CFU/g were found with cabbage and tomato, respectively, at a similar dose. The appearance, color, texture, taste, and overall acceptability did not undergo significant changes after 7 days of postirradiation storage at 4 degrees C, in comparison with control samples. Therefore, low-dose ionizing radiation treatment could be an effective method for eliminating L. monocytogenes on fresh and fresh-cut produce.

Radiation inactivation of ricin occurs with transfer of destructive energy across a disulfide bridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haigler, H.T.; Woodbury, D.J.; Kempner, E.S.

1985-08-01

The ionizing radiation sensitivity of ricin, a disulfide-linked heterodimeric protein, was studied as a model to determine the ability of disulfide bonds to transmit destructive energy. The radiation-dependent loss of A chain enzymatic activity after irradiation of either intact ricin or ricin in which the interchain disulfide bond was disrupted gave target sizes corresponding to the molecular size of dimeric ricin or monomeric A chain, respectively. These results clearly show that a disulfide bond can transmit destructive energy between protein subunits.

Determination of Time Dependent Virus Inactivation Rates

NASA Astrophysics Data System (ADS)

Chrysikopoulos, C. V.; Vogler, E. T.

2003-12-01

A methodology is developed for estimating temporally variable virus inactivation rate coefficients from experimental virus inactivation data. The methodology consists of a technique for slope estimation of normalized virus inactivation data in conjunction with a resampling parameter estimation procedure. The slope estimation technique is based on a relatively flexible geostatistical method known as universal kriging. Drift coefficients are obtained by nonlinear fitting of bootstrap samples and the corresponding confidence intervals are obtained by bootstrap percentiles. The proposed methodology yields more accurate time dependent virus inactivation rate coefficients than those estimated by fitting virus inactivation data to a first-order inactivation model. The methodology is successfully applied to a set of poliovirus batch inactivation data. Furthermore, the importance of accurate inactivation rate coefficient determination on virus transport in water saturated porous media is demonstrated with model simulations.

Inactivation of Heterosigma akashiwo in ballast water by circular orifice plate-generated hydrodynamic cavitation.

PubMed

Feng, Daolun; Zhao, Jie; Liu, Tian

2016-01-01

The discharge of alien ballast water is a well-known, major reason for marine species invasion. Here, circular orifice plate-generated hydrodynamic cavitation was used to inactivate Heterosigma akashiwo in ballast water. In comparison with single- and multihole orifice plates, the conical-hole orifice plate yielded the highest inactivation percentage, 51.12%, and consumed only 6.84% energy (based on a 50% inactivation percentage). Repeating treatment, either using double series-connection or circling inactivation, elevated the inactivation percentage, yet consumed much more energy. The results indicate that conical-hole-generated hydrodynamic cavitation shows great potential as a pre-inactivation method for ballast water treatment.

Laser inactivation of pathogenic viruses in water

NASA Astrophysics Data System (ADS)

Grishkanich, Alexander; Zhevlakov, Alexander; Kascheev, Sergey; Sidorov, Igor; Ruzankina, Julia; Yakovlev, Alexey; Mak, Andrey

2016-03-01

Currently there is a situation that makes it difficult to provide the population with quality drinking water for the sanitary-hygienic requirements. One of the urgent problems is the need for water disinfection. Since the emergence of microorganisms that are pathogens transmitted through water such as typhoid, cholera, etc. requires constant cleansing of waters against pathogenic bacteria. In the water treatment process is destroyed up to 98% of germs, but among the remaining can be pathogenic viruses, the destruction of which requires special handling. As a result, the conducted research the following methods have been proposed for combating harmful microorganisms: sterilization of water by laser radiation and using a UV lamp.

Beneficial uses program. Progress report ending December 31, 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1980-06-01

Progress is reported in research on uses of irradiated sewage sludge, particularly as a cattle feed supplement and commercial fertilizer additive, on potential sites for irradiator demonstration plants, and on the inactivation of enteric bacteria by radiation treatment. (LCL)

INACTIVATION OF CRYPTOSPORIDIUM PARVUM OOCYSTS WITH OZONE

EPA Science Inventory

Ozone inactivation rates for Cryptosporidium parvum (C. parvum) oocysts were determined with an in-vitro excystation method based on excysted sporozoite counts. Results were consistent with published animal infectivity data for the same C. parvum strain. The inactivation kinetics...

Beneficial uses program. Progress report for period ending March 31, 1977

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1977-07-01

Progress is reported in a program aimed at recovering radiation sources from radioactive wastes and using these sources, mainly /sup 137/Cs, for irradiating sewage sludge. Information is included on: development and cost of dried sludge irradiator; heat and radiation inactivation of sludge-contained viruses and bacteria; virucidal agents in sludge; use of thermoradiated sludge as animal feed; and a comparison of the efficiency of various source materials. (LCL)

Radiation-Dependent Limit for the Viability of Bacterial Spores in Halite Fluid Inclusions and on Mars

PubMed Central

Kminek, Gerhard; Bada, Jeffrey L.; Pogliano, Kit; Ward, John F.

2014-01-01

Kminek, G., Bada, J. L., Pogliano, K. and Ward, J. F. Radiation-Dependent Limit for the Viability of Bacterial Spores in Halite Fluid Inclusions and on Mars. Radiat. Res. 159, 722–729 (2003). When claims for the long-term survival of viable organisms are made, either within terrestrial minerals or on Mars, considerations should be made of the limitations imposed by the naturally occurring radiation dose to which they have been exposed. We investigated the effect of ionizing radiation on different bacterial spores by measuring the inactivation constants for B. subtilis and S. marismortui spores in solution as well as for dry spores of B. subtilis and B. thuringiensis. S. marismortui is a halophilic spore that is genetically similar to the recently discovered 2-9-3 bacterium from a halite fluid inclusion, claimed to be 250 million years old (Vreeland et al., Nature 407, 897–900, 2000). B. thuringiensis is a soil bacterium that is genetically similar to the human pathogens B. anthracis and B. cereus (Helgason et al., Appl. Environ. Microbiol. 66, 2627–2630, 2000). To relate the inactivation constant to some realistic environments, we calculated the radiation regimen in a halite fluid inclusion and in the Martian subsurface over time. Our conclusion is that the ionizing dose of radiation in those environments limits the survival of viable bacterial spores over long periods. In the absence of an active repair mechanism in the dormant state, the long-term survival of spores is limited to less than 109 million years in halite fluid inclusions, to 100 to 160 million years in the Martian subsurface below 3 m, and to less than 600,000 years in the uppermost meter of Mars. PMID:12751954

Effects of Different Pretreatments to Fresh Fruit on Chemical and Thermal Characteristics of Crude Palm Oil.

PubMed

Tang, Minmin; Xia, Qiuyu; Holland, Brendan J; Wang, Hui; Zhang, Yufeng; Li, Rui; Cao, Hongxing

2017-12-01

This study selected 5 methods, including boiling, hot air drying, high-pressurized steam, freezing, and microwave radiation to pretreat fresh oil palm fruit before solvent extraction of the oil. Using fresh fruit as a control, the pretreatment methods were compared for the effects on the activity of the 2 main enzymes in the fruit and some physicochemical properties of the crude palm oil. The results indicated, although all the 5 pretreatments could inactivate lipase and peroxidase in the treated flesh significantly (P < 0.05), the high-pressurized steam was the most effective. There were also differences in the unsaturated fatty acid contents of the 6 oils. The crude oil from frozen fruit contained significantly more vitamin E (37829.33 ppm) than previously reported. Microwave radiation was shown to significantly decrease the free fatty acid content and the peroxide value, while increasing the oxidative stability index. Thermal behaviors of the oils were significantly different to each other with the exception a few parameters (P < 0.05). © 2017 Institute of Food Technologists®.

Ultraviolet radiation from the pulsed corona discharge in water

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Sunka, Pavel

2008-05-01

Quantitative analysis of ultraviolet radiation from the pulsed corona discharge in water with needle-plate electrode geometry (~1-3 J pulse-1) was performed using the potassium ferrioxalate actinometry. Photon flux J190-280 and radiant energy Q190-280 of the UV light emitted from the discharge at spectral region 190-280 nm was determined in dependence on the applied voltage (17-29 kV, positive polarity) and the solution conductivity (100-500 µS cm-1). The intensity of the UV radiation strongly increased with increasing water conductivity and applied voltage. Depending on the applied voltage the determined photon flux varied by more than two orders of magnitude within the range of solution conductivities 100-500 µS cm-1. It was found that photon flux from the discharge may be directly related to the discharge pulse mean power Pp as J190-280 = 44.33 P_p^{2.11} (quanta pulse-1). A significant role of UV radiation in the production of hydrogen peroxide and bacterial inactivation by the corona discharge in water has been identified. As the solution conductivity increased the yield of H2O2 produced by the discharge decreased due to increasing photolysis of H2O2 accounting for up to 14% of the total decomposition rate of H2O2. As regards bactericidal effects, it was estimated that the UV radiation contributes about 30% to the overall inactivation of Escherichia coli.

Disruption of diphthamide synthesis genes and resulting toxin resistance as a robust technology for quantifying and optimizing CRISPR/Cas9-mediated gene editing.

PubMed

Killian, Tobias; Dickopf, Steffen; Haas, Alexander K; Kirstenpfad, Claudia; Mayer, Klaus; Brinkmann, Ulrich

2017-11-13

We have devised an effective and robust method for the characterization of gene-editing events. The efficacy of editing-mediated mono- and bi-allelic gene inactivation and integration events is quantified based on colony counts. The combination of diphtheria toxin (DT) and puromycin (PM) selection enables analyses of 10,000-100,000 individual cells, assessing hundreds of clones with inactivated genes per experiment. Mono- and bi-allelic gene inactivation is differentiated by DT resistance, which occurs only upon bi-allelic inactivation. PM resistance indicates integration. The robustness and generalizability of the method were demonstrated by quantifying the frequency of gene inactivation and cassette integration under different editing approaches: CRISPR/Cas9-mediated complete inactivation was ~30-50-fold more frequent than cassette integration. Mono-allelic inactivation without integration occurred >100-fold more frequently than integration. Assessment of gRNA length confirmed 20mers to be most effective length for inactivation, while 16-18mers provided the highest overall integration efficacy. The overall efficacy was ~2-fold higher for CRISPR/Cas9 than for zinc-finger nuclease and was significantly increased upon modulation of non-homologous end joining or homology-directed repair. The frequencies and ratios of editing events were similar for two different DPH genes (independent of the target sequence or chromosomal location), which indicates that the optimization parameters identified with this method can be generalized.

Molecular Viability Testing of UV-Inactivated Bacteria.

PubMed

Weigel, Kris M; Nguyen, Felicia K; Kearney, Moira R; Meschke, John S; Cangelosi, Gerard A

2017-05-15

PCR is effective in detecting bacterial DNA in samples, but it is unable to differentiate viable bacteria from inactivated cells or free DNA fragments. New PCR-based analytical strategies have been developed to address this limitation. Molecular viability testing (MVT) correlates bacterial viability with the ability to rapidly synthesize species-specific rRNA precursors (pre-rRNA) in response to brief nutritional stimulation. Previous studies demonstrated that MVT can assess bacterial inactivation by chlorine, serum, and low-temperature pasteurization. Here, we demonstrate that MVT can detect inactivation of Escherichia coli , Aeromonas hydrophila , and Enterococcus faecalis cells by UV irradiation. Some UV-inactivated E. coli cells transiently retained the ability to synthesize pre-rRNA postirradiation (generating false-positive MVT results), but this activity ceased within 1 h following UV exposure. Viable but transiently undetectable (by culture) E. coli cells were consistently detected by MVT. An alternative viability testing method, viability PCR (vPCR), correlates viability with cell envelope integrity. This method did not distinguish viable bacteria from UV-inactivated bacteria under some conditions, indicating that the inactivated cells retained intact cell envelopes. MVT holds promise as a means to rapidly assess microbial inactivation by UV treatment. IMPORTANCE UV irradiation is increasingly being used to disinfect water, food, and other materials for human use. Confirming the effectiveness of UV disinfection remains a challenging task. In particular, microbiological methods that rely on rapid detection of microbial DNA can yield misleading results, due to the detection of remnant DNA associated with dead microbial cells. This report describes a novel method that rapidly distinguishes living microbial cells from dead microbial cells after UV disinfection. Copyright © 2017 American Society for Microbiology.

Physiology of the Inactivation of Vegetative Bacteria by Thermal Treatments: Mode of Action, Influence of Environmental Factors and Inactivation Kinetics

PubMed Central

Condón, Santiago; Mañas, Pilar

2017-01-01

Heat has been used extensively in the food industry as a preservation method, especially due to its ability to inactivate microorganisms present in foods. However, many aspects regarding the mechanisms of bacterial inactivation by heat and the factors affecting this process are still not fully understood. The purpose of this review is to offer a general overview of the most important aspects of the physiology of the inactivation or survival of microorganisms, particularly vegetative bacteria, submitted to heat treatments. This could help improve the design of current heat processes methods in order to apply milder and/or more effective treatments that could fulfill consumer requirements for fresh-like foods while maintaining the advantages of traditional heat treatments. PMID:29189748

Solar and temporal effects on Escherichia coli concentration at a Lake Michigan swimming beach

USGS Publications Warehouse

Whitman, Richard L.; Nevers, Meredith B.; Korinek, Ginger C.; Byappanahalli, Muruleedhara N.

2004-01-01

Studies on solar inactivation of Escherichia coli in freshwater and in situ have been limited. At 63rd St. Beach, Chicago, Ill., factors influencing the daily periodicity of culturable E. coli, particularly insolation, were examined. Water samples for E. coli analysis were collected twice daily between April and September 2000 three times a week along five transects in two depths of water. Hydrometeorological conditions were continuously logged: UV radiation, total insolation, wind speed and direction, wave height, and relative lake level. On 10 days, transects were sampled hourly from 0700 to 1500 h. The effect of sunlight on E. coliinactivation was evaluated with dark and transparent in situ mesocosms and ambient lake water. For the study, the number of E. coli samples collected (n) was 2,676. During sunny days, E. coli counts decreased exponentially with day length and exposure to insolation, but on cloudy days, E. coli inactivation was diminished; the E. coli decay rate was strongly influenced by initial concentration. In situ experiments confirmed that insolation primarily inactivated E. coli; UV radiation only marginally affected E. coliconcentration. The relationship between insolation and E. coli density is complicated by relative lake level, wave height, and turbidity, all of which are often products of wind vector. Continuous importation and nighttime replenishment of E. coli were evident. These findings (i) suggest that solar inactivation is an important mechanism for natural reduction of indicator bacteria in large freshwater bodies and (ii) have implications for management strategies of nontidal waters and the use of E. coli as an indicator organism.

In situ method for estimating cell survival in a solid tumor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alfieri, A.A.; Hahn, E.W.

1978-09-01

The response of the murine Meth-A fibrosarcoma to single and fractionated doses of x-irradiation, actinomycin D chemotherapy, and/or concomitant local tumor hyperthermia was assayed with the use of an in situ method for estimating cell kill within a solid tumor. The cell survival assay was based on a standard curve plotting number of inoculated viable cells with and without radiation-inactivated homologous tumor cells versus the time required for i.m. tumors to grow to 1.0 cu cm. The time for post-treatment tumors to grow to 1.0 cu cm was cross-referenced to the standard curve, and the number of surviving cells contributingmore » to tumor regrowth was estimated. The resulting surviving fraction curves closely resemble those obtained with in vitro systems.« less

Inactivation, DNA double strand break induction and their rejoining in bacterial cells irradiated with heavy ions

NASA Technical Reports Server (NTRS)

Schaefer, M.; Zimmermann, H.; Schmitz, C.

1994-01-01

Besides inactivation one of the major interests in our experiments is to study the primary damage in the DNA double strand breaks (DSB) after heavy ion irradiation. These damages lead not only to cell death but also under repair activities to mutations. In further experiments we have investigated the inactivation with two different strains of Deinococcus radiodurans (R1, Rec 30) and the induction of DSB as well as the rejoining of DSB in stationary cells of E. coli (strain B/r) irradiated with radiations of different quality. In the latter case irradiations were done so that the cell survival was roughly at the same level. We measured the DSB using the pulse field gelelectrophoresis which allows to separate between intact (circular) and damaged (linear) DNA. The irradiated cells were transferred to NB medium and incubated for different times to allow rejoining.

Application of electrolysis to inactivation of antibacterials in clinical use.

PubMed

Nakano, Takashi; Hirose, Jun; Kobayashi, Toyohide; Hiro, Naoki; Kondo, Fumitake; Tamai, Hiroshi; Tanaka, Kazuhiko; Sano, Kouichi

2013-04-01

Contamination of surface water by antibacterial pharmaceuticals (antibacterials) from clinical settings may affect aquatic organisms, plants growth, and environmental floral bacteria. One of the methods to decrease the contamination is inactivation of antibacterials before being discharged to the sewage system. Recently, we reported the novel method based on electrolysis for detoxifying wastewater containing antineoplastics. In the present study, to clarify whether the electrolysis method is applicable to the inactivation of antibacterials, we electrolyzed solutions of 10 groups of individual antibacterials including amikacin sulfate (AMK) and a mixture (MIX) of some commercial antibacterials commonly prescribed at hospitals, and measured their antibacterial activities. AMK was inactivated in its antibacterial activities and its concentration decreased by electrolysis in a time-dependent manner. Eighty to ninety-nine percent of almost all antibacterials and MIX were inactivated within 6h of electrolysis. Additionally, cytotoxicity was not detected in any of the electrolyzed solutions of antibacterials and MIX by the Molt-4-based cytotoxicity test. Copyright © 2012 Elsevier Inc. All rights reserved.

Induction of gynogenetic and androgenetic haploid and doubled haploid development in the brown trout (Salmo trutta Linnaeus 1758).

PubMed

Michalik, O; Dobosz, S; Zalewski, T; Sapota, M; Ocalewicz, K

2015-04-01

Gynogenetic and androgenetic brown trout (Salmo trutta Linnaeus 1758) haploids (Hs) and doubled haploids (DHs) were produced in the present research. Haploid development was induced by radiation-induced genetic inactivation of spermatozoa (gynogenesis) or eggs (androgenesis) before insemination. To provide DHs, gynogenetic and androgenetic haploid zygotes were subjected to the high pressure shock to suppress the first mitotic cleavage. Among haploids, gynogenetic embryos were showing lower mortality when compared to the androgenetic embryos; however, most of them die before the first feeding stage. Gynogenetic doubled haploids provided in the course of the brown trout eggs activation performed by homologous and heterologous sperm (rainbow trout) were developing equally showing hatching rates of 14.76 ± 2.4% and 16.14 ± 2.90% and the survival rates at the first feeding stage of 10.48 ± 3.48% and 12.78 ± 2.18%, respectively. Significantly, lower survival rate was observed among androgenetic progenies from the diploid groups with only few specimens that survived to the first feeding stage. Cytogenetic survey showed that among embryos from the diploid variants of the research, only gynogenetic individuals possessed doubled sets of chromosomes. Thus, it is reasonable to assume that radiation employed for the genetic inactivation of the brown trout eggs misaligned mechanism responsible for the cell divisions and might have delayed or even arrested the first mitotic cleavage in the androgenetic brown trout zygotes. Moreover, protocol for the radiation-induced inactivation of the paternal and maternal genome should be adjusted as some of the cytogenetically surveyed gynogenetic and androgenetic embryos exhibited fragments of the irradiated chromosomes. © 2015 Blackwell Verlag GmbH.

Inactivation of pathogenic bacteria in food matrices: high pressure processing, photodynamic inactivation and pressure-assisted photodynamic inactivation

NASA Astrophysics Data System (ADS)

Cunha, A.; Couceiro, J.; Bonifácio, D.; Martins, C.; Almeida, A.; Neves, M. G. P. M. S.; Faustino, M. A. F.; Saraiva, J. A.

2017-09-01

Traditional food processing methods frequently depend on the application of high temperature. However, heat may cause undesirable changes in food properties and often has a negative impact on nutritional value and organoleptic characteristics. Therefore, reducing the microbial load without compromising the desirable properties of food products is still a technological challenge. High-pressure processing (HPP) can be classified as a cold pasteurization technique, since it is a non-thermal food preservation method that uses hydrostatic pressure to inactivate spoilage microorganisms. At the same time, it increases shelf life and retains the original features of food. Photodynamic inactivation (PDI) is also regarded as promising approach for the decontamination of food matrices. In this case, the inactivation of bacterial cells is achieved by the cytotoxic effects of reactive oxygens species (ROS) produced from the combined interaction of a photosensitizer molecule, light and oxygen. This short review examines some recent developments on the application of HPP and PDI with food-grade photosensitizers for the inactivation of listeriae, taken as a food pathogen model. The results of a proof-of-concept trial of the use of high-pressure as a coadjutant to increase the efficiency of photodynamic inactivation of bacterial endospores is also addressed.

UV disinfection and flocculation-chlorination sachets to reduce hepatitis E virus in drinking water.

PubMed

Guerrero-Latorre, Laura; Gonzales-Gustavson, Eloy; Hundesa, Ayalkibet; Sommer, Regina; Rosina, Girones

2016-07-01

Hepatitis E Virus (HEV) is a major cause of waterborne outbreaks in areas with poor sanitation. As safe water supplies are the keystone for preventing HEV outbreaks, data on the efficacy of disinfection treatments are urgently needed. Here, we evaluated the ability of UV radiation and flocculation-chlorination sachets (FCSs) to reduce HEV in water matrices. The HEV-p6-kernow strain was replicated in the HepG2/C3A cell line, and we quantified genome number using qRT-PCR and infectivity using an immunofluorescence assay (IFA). UV irradiation tests using low-pressure radiation showed inactivation kinetics for HEV of 99.99% with a UV fluence of 232J/m(2) (IC 95%, 195,02-269,18). Moreover, the FCSs preparations significantly reduced viral concentrations in both water matrices, although the inactivation results were under the baseline of reduction (4.5 LRV) proposed by WHO guidelines. Copyright © 2016 Elsevier GmbH. All rights reserved.

Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, L.; Wiesehahn, G.P.; Morel, P.A.

1989-07-01

Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17more » and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions.« less

Susceptibility of ATM-deficient pancreatic cancer cells to radiation.

PubMed

Ayars, Michael; Eshleman, James; Goggins, Michael

2017-05-19

Ataxia telangiectasia mutated (ATM) is inactivated in a significant minority of pancreatic ductal adenocarcinomas and may be predictor of treatment response. We determined if ATM deficiency renders pancreatic cancer cells more sensitive to fractionated radiation or commonly used chemotherapeutics. ATM expression was knocked down in three pancreatic cancer cell lines using ATM-targeting shRNA. Isogenic cell lines were tested for sensitivity to several chemotherapeutic agents and radiation. DNA repair kinetics were analyzed in irradiated cells using the comet assay. We find that while rendering pancreatic cancer cells ATM-deficient did not significantly change their sensitivity to several chemotherapeutics, it did render them exquisitely sensitized to radiation. Pancreatic cancer ATM status may help predict response to radiotherapy.

CDKN2A/p16 inactivation mechanisms and their relationship to smoke exposure and molecular features in non-small cell lung cancer

PubMed Central

Tam, Kit W.; Zhang, Wei; Soh, Junichi; Stastny, Victor; Chen, Min; Sun, Han; Thu, Kelsie; Rios, Jonathan J.; Yang, Chenchen; Marconett, Crystal N.; Selamat, Suhaida A.; Laird-Offringa, Ite A; Taguchi, Ayumu; Hanash, Samir; Shames, David; Ma, Xiaotu; Zhang, Michael Q; Lam, Wan L.; Gazdar, Adi

2013-01-01

Introduction CDKN2A(p16) inactivation is common in lung cancer and occurs via homozygous deletions (HD), methylation of promoter region, or point mutations. While p16 promoter methylation has been linked to KRAS mutation and smoking, the associations between p16 inactivation mechanisms and other common genetic mutations and smoking status are still controversial or unknown. Methods We determined all three p16 inactivation mechanisms using multiple methodologies for genomic status, methylation, RNA and protein expression, and correlated them with EGFR, KRAS, STK11 mutations and smoking status in 40 cell lines and 45 tumor samples of primary NSCLC. We also performed meta-analyses to investigate the impact of smoke exposure on p16 inactivation. Results p16 inactivation was the major mechanism of RB pathway perturbation in NSCLC, with HD being the most frequent method, followed by methylation and the rarer point mutations. Inactivating mechanisms were tightly correlated with loss of mRNA and protein expression. p16 inactivation occurred at comparable frequencies regardless of mutational status of EGFR, KRAS and STK11, however, the major inactivation mechanism of p16 varied. p16 methylation was linked to KRAS mutation but was mutually exclusive with EGFR mutation. Cell lines and tumor samples demonstrated similar results. Our meta-analyses confirmed a modest positive association between p16 promoter methylation and smoking. Conclusions Our results confirm that all of the inactivation mechanisms are truly associated with loss of gene product and identify specific associations between p16 inactivation mechanisms and other genetic changes and smoking status. PMID:24077454

UV Disinfection System for Cabin Air

NASA Astrophysics Data System (ADS)

Lim, Soojung

Ultraviolet (UV) radiation is commonly used for disinfection of water. As a result of advancements made in the last 10-15 years, the analysis and design of UV disinfection systems for water is well developed. UV disinfection is also used for disinfection of air; however, despite the fact the UV-air systems have a longer record of application than UV-water systems, the methods used to analyze and design UV-air disinfection systems remain quite empirical. It is well-established that the effectiveness of UV-air systems is strongly affected by the type of microorganisms, the irradiation level/type (lamp power and wavelength), duration of irradiation (exposure time), air movement pattern (mixing degree), and relative humidity. This paper will describe ongoing efforts to evaluate, design and test a UV-air system based on first principles. Specific issues to be addressed in this work will include laboratory measurements of relevant kinetics (i.e., UV dose-response behavior) and numerical simulations designed to represent fluid mechanics and the radiation intensity field. UV dose-response behavior of test microorganism was measured using a laboratory (bench-scale) system. Target microorganisms (e.g., bacterial spores) were first applied to membrane filters at sub-monolayer coverage. The filters were then transferred to an environmental chamber at fixed relative humidity (RH) and allowed to equilibrate with their surroundings. Microorganisms were then subjected to UV exposure under a collimated beam. The experiment was repeated at RH values ranging from 20% to 100%. UV dose-response behavior was observed to vary with RH. For example, at 100% RH, a UV dose of 20 mJ/cm2 accomplished 90% (1 log10 units) of the B. subtilis spore inactivation, whereas 99 % (2 log10 units) inactivation was accomplished at this same UV dose under 20% RH conditions. However, at higher doses, the result was opposite of that in low dose. Reactor behavior is simulated using an integrated application of computational fluid dynamics (CFD) and radiation intensity field models. These simulations followed a Lagrangian approach, wherein the UV radiation intensity field was mapped onto simulated particle trajectories for prediction of the UV dose delivered to each particle. By repeating these calculations for a large number of simulated particle trajectories, an estimate of the UV dose distribution delivered by the reactor can be made. In turn, these dose distribution estimates are integrated with the UV dose-response behavior described above to yield an estimate of microbial inactivation accomplished by the reactor. This modeling approach has the advantage of allowing simulation of many reactor configurations in a relatively short period of time. Moreover, by following this approach of "numerical prototyping," it is possible to "build" and analyze several virtual reactors before the construction of a physical prototype. As such, this procedure allows effective development of efficient reactors.

Analysis of Genotoxic and Cytotoxic Responses Induced by Simulated Space Radiation Qualities by Use of Recombinant Bacteria Carrying a Dual-Function Dual-Reporter Construct

NASA Astrophysics Data System (ADS)

Baumstark-Khan, Christa; Hellweg, Christine; Zahoor, Ahmed; Testard, Isabelle; Reitz, Guenther

Along with the long-term space exploration come various potential health risks due to unique physical factors of the space environment. Space radiation is one of the primary environmental hazards associated with space flight. In order to deal with space-related risk radiation exposure must be properly characterised and quantified, and biological effects of charged particles have to be analysed in ground based research, especially as astronauts are subjected to a differing radiation quality in space than they receive on Earth. For risk assessment, the mutagenic potential of the heavy ion component of the galactic cosmic radiation is of major concern for tumour induction as radiation late effects. The recombinant SWITCH test is based on TA1535 Salmonella typhimurium cells transformed with a dual-function dual-reporter vector harbouring (a) the genes for bioluminescence production from Photobacterium leiognathi under the control of a DNA-damage inducible promoter and (b) the gene for green fluorescent protein from the jellyfish Aequorea victoria under the control of a constitutive promoter. Suchlike genetically modified organism report on the presence of genotoxic conditions by dose dependent increase of bioluminescence induction and on the presence of cytotoxic conditions by dose dependent decrease in GFP fluorescence. By this, it is possible to analyse bacterial inactivation and mutation induction by ionizing radiation in parallel in the same cell within short time. Experiments with heavy ions have been performed with the SWITCH test at GANIL with the following accelerated heavy ions: 35 MeV/u (72 keV/µm) and 75 MeV/u (37 keV/µm) carbon, 95 MeV/u argon (377 keV/µm), 95 MeV/u neon (98 keV/µm), 75 MeV/u nickel (967 keV/µm) and 29 MeV/u lead (10238 keV/µm). The results obtained clearly show that the numbers of hits (particles per cm2 ) necessary to inactivate the bacteria (cytotoxicity) depend on LET. The higher the ionisation capacity of the accelerated ion, the less hits resulted in the same test effect, e.g. 37 % survival. For genotoxicity induction it can be seen, that for very high LET radiation the number of hits required is much less then for lower LET radiation (e.g. 1.4x106 /cm2 hits for lead versus 1.3x107 /cm2 hits for carbon). The power of the genotoxic response seems to be inversely related to LET. While 200 kV X-rays induced a 99.6x induction, carbon radiation results in a maximal induction of 72.6x (37 keV/m) and of 76.5x (72 keV/m), argon radiation (377 keV/m) leads to a 29.4x value, neon radiation (98 keV/m) leads to a 16.1x value, nickel radiation (967 keV/m) leads to a 15.4x value and lead radiation (10238 keV/m) results in only a factor of 4.8. Inactivation cross sections (σRCP) peak at a LET between 100 and 300 keV/m. The same is true for genotoxicity cross sections (σRGP for 2x), while maximal luminescence emission (for peak response) decreases with increasing LET. The response of the SWITCH test to space radiation qualities can be seen as indicative for an increased astronauts' risk from high LET radiation.

INACTIVATION OF SOME SEMISYNTHETIC PENICILLINS BY GRAM-NEGATIVE BACILLI

PubMed Central

Sabath, Leon; Finland, Maxwell

1963-01-01

Sabath, Leon (Boston City Hospital, Boston, Mass.) and Maxwell Finland. Inactivation of some semisynthetic penicillins by gram-negative bacilli. J. Bacteriol. 85:314–321. 1963.—An agar diffusion method was used to test 55 strains of gram-negative bacilli for their ability to inactivate penicillin G, methicillin, biphenylpenicillin, oxacillin, and ampicillin; 26 strains inactivated one or more of them. All strains of Klebsiella-Aerobacter, nearly all of Escherichia coli, and some of Pseudomonas aeruginosa, but not those of Proteus or Salmonella, were active by this method. Penicillin G was inactivated by the largest number of strains, biphenylpenicillin and ampicillin by somewhat fewer, and oxacillin and methicillin by about half as many. When the five penicillins were incubated with four strains of different bacteria in broth at 37 C, all were inactivated to a considerable extent by all the strains, each penicillin to a different degree, but to about the same extent by all the strains. Adsorption alone did not account for the loss of activity. The results suggest that there are qualitative, as well as quantitative, differences among species or even strains of gram-negative bacilli in their ability to inactivate the various penicillins. Images PMID:13975857

Simultaneous atrazine degradation and E. coli inactivation by simulated solar photo-Fenton-like process using persulfate.

PubMed

Garkusheva, Natalya; Matafonova, Galina; Tsenter, Irina; Beck, Sara; Batoev, Valeriy; Linden, Karl

2017-07-29

This work evaluated the feasibility of a photo-Fenton-like process using persulfate (PS) and ferrous iron (Fe 2+ ) under simulated solar radiation for degrading the herbicide atrazine (ATZ, 6-Chloro-N-ethyl-N'-isopropyl-1,3,5-triazine-2,4-diamine) and inactivating E. coli. Milli Q water, lake water, and diluted wastewater effluents were spiked both simultaneously and separately with ATZ (4 mg/L) and E. coli (10 5 CFU/mL), and exposed to treatment. A method for determining the average irradiance throughout the water media in the UV(A+B) range of the Xe lamp emission was developed for bench-scale experiments. These values were used to calculate the UV(A+B) fluences and the solar UV(A+B) energy doses per unit of volume (Q UV(A+B) , kJ/L). The obtained kinetic data were presented versus energy dose. Treatment of lake water at near-neutral pH was ineffective via the photo-Fenton-like process, attaining only 20% ATZ removal and 1-log reduction of E. coli. In Milli Q water and wastewater, the complete degradation of ATZ in the absence of bacteria was observed at an average energy dose of 1.5 kJ/L (60 min), while in the presence of cells the degradation efficiency was ∼60%. When ATZ was present, E. coli inactivation was also affected in Milli Q water, with 1.4-log reduction (93%) at a dose of 1.6 kJ/L (60 min), whereas in wastewater complete inactivation was achieved at a lower dose of 1.3 kJ/L (45 min). The energy requirements on a Q UV(A+B) basis for simultaneous 90% ATZ removal and 99.99% E. coli inactivation in Milli Q water and wastewater were shown to be less than 10 kJ/L. This suggests the solar/PS/Fe 2+ system is promising for simultaneous treatment and disinfection of wastewater effluents.

Curing conditions to inactivate Trichinella spiralis muscle larvae in ready-to-eat pork sausage

USDA-ARS?s Scientific Manuscript database

Curing processes for ready to eat (RTE) pork products currently require individual validation of methods to demonstrate inactivation of Trichinella spiralis. This is a major undertaking for each process; currently no model of meat chemistry exists that can be correlated with inactivation of Trichin...

Biophysical damage in metallo-enzyme and mammalian cells by Cu-K X-rays and radioisotopes

NASA Astrophysics Data System (ADS)

Younis, Abdul-Redha Sahib

In the fields of radiobiology and nuclear medicine there is considerable interest in the important role played by Auger electron cascades caused by inner-shell ionisation in realistic risk. It is necessary to quantify this risk when radionuclides are used on a routine basis as investigative, diagnostic and radiotherapeutic tools, whether the applications involve incorporated electron capture radionuclides or K-shell ionisation of selected stable nuclides by X-rays, as in "photon activation therapy". Relevant published survival data on biological damage caused by the internal emitters 125I, 77Br, 3H, 33P, 131I and 32P which are incorporated into the DNA of mammalian cells, bacteria (E. Coli) and bacteriophages have been collected and the results re-analysed in terms of the parameters of a new damage model to determine an inactivation cross-section for each internal emitter. These quality parameters are the absolute specification of radiation quality and are compared with cross-sections similarly determined for the effects of external radiations from heavy charged particles and photons (chapter 2). The inactivation probabilities obtained for the nuclides 125I, 77Br and 3H extend over a wide range of values depending on the type of nuclide and its distribution, the type of sensitive target and its shape and distribution, and the environmental temperature during both irradiation and post-irradiation incubation. The higher values approach those determined for heavy charged particles with the same mean free path for primary ionisation, and are an order of magnitude larger than would be expected for external irradiation with photon generated electrons. The results for 33P, 131I and 32P nuclides are appreciably smaller than that expected for external irradiation since the long range electrons dissipate most of their energy out of the sensitive target. A theoretical equation for X-ray production by accelerated electrons incident on a thick target has been revised by including factors to compensate for backscattering, direct and indirect ionisation, attenuation in the target and the incident angle of electrons (chapter 3). An electron accelerator X-ray machine capable of delivering monoenergetic photons up to 4.8 gray/sec exposure dose rate from four different targets has been designed, constructed and tested (chapter 4) The biophysical mechanisms of direct and indirect radiation action has also been studied using the metallo-enzyme dihydroorotic dehydrogenase. The enzyme was irradiated both in dry state and in solution at different concentrations and at different dose rates using monoenergetic Cu-K photons from our X-ray machine. A technique was developed whereby it was possible to isolate and quantify each type of radiation action (chapter 5). The inactivation of the enzyme in both solution and in dry state was found to be a single-hit/single-target process. It was also found that in solution the inactivation of the enzyme was dose-rate-and concentration-dependent with efficiency of radical inactivation has an exponential dependence on dose-rate and the inverse of the enzyme concentration. A new model for the inactivation of the enzyme has been suggested and its parameters, namely direct and indirect cross-sections, geometrical cross-section, saturated concentration constant, root mean square diffusion constant, mean free path of radicals absorption, life time and G value of radical production, have been determined. It is expected that this model can be generalised to suit other enzymes (chapter 6).

Avirulent Bacillus anthracis Strain with Molecular Assay Targets as Surrogate for Irradiation-Inactivated Virulent Spores.

PubMed

Plaut, Roger D; Staab, Andrea B; Munson, Mark A; Gebhardt, Joan S; Klimko, Christopher P; Quirk, Avery V; Cote, Christopher K; Buhr, Tony L; Rossmaier, Rebecca D; Bernhards, Robert C; Love, Courtney E; Berk, Kimberly L; Abshire, Teresa G; Rozak, David A; Beck, Linda C; Stibitz, Scott; Goodwin, Bruce G; Smith, Michael A; Sozhamannan, Shanmuga

2018-04-01

The revelation in May 2015 of the shipment of γ irradiation-inactivated wild-type Bacillus anthracis spore preparations containing a small number of live spores raised concern about the safety and security of these materials. The finding also raised doubts about the validity of the protocols and procedures used to prepare them. Such inactivated reference materials were used as positive controls in assays to detect suspected B. anthracis in samples because live agent cannot be shipped for use in field settings, in improvement of currently deployed detection methods or development of new methods, or for quality assurance and training activities. Hence, risk-mitigated B. anthracis strains are needed to fulfill these requirements. We constructed a genetically inactivated or attenuated strain containing relevant molecular assay targets and tested to compare assay performance using this strain to the historical data obtained using irradiation-inactivated virulent spores.

Inactivation of RNA Viruses by Gamma Irradiation: A Study on Mitigating Factors

PubMed Central

Hume, Adam J.; Ames, Joshua; Rennick, Linda J.; Duprex, W. Paul; Marzi, Andrea; Tonkiss, John; Mühlberger, Elke

2016-01-01

Effective inactivation of biosafety level 4 (BSL-4) pathogens is vital in order to study these agents safely. Gamma irradiation is a commonly used method for the inactivation of BSL-4 viruses, which among other advantages, facilitates the study of inactivated yet morphologically intact virions. The reported values for susceptibility of viruses to inactivation by gamma irradiation are sometimes inconsistent, likely due to differences in experimental protocols. We analyzed the effects of common sample attributes on the inactivation of a recombinant vesicular stomatitis virus expressing the Zaire ebolavirus glycoprotein and green fluorescent protein. Using this surrogate virus, we found that sample volume and protein content of the sample modulated viral inactivation by gamma irradiation but that air volume within the sample container and the addition of external disinfectant surrounding the sample did not. These data identify several factors which alter viral susceptibility to inactivation and highlight the usefulness of lower biosafety level surrogate viruses for such studies. Our results underscore the need to validate inactivation protocols of BSL-4 pathogens using “worst-case scenario” procedures to ensure complete sample inactivation. PMID:27455307

Patents for Toll-like receptor ligands as radiation countermeasures for acute radiation syndrome.

PubMed

Singh, Vijay K; Pollard, Harvey B

2015-01-01

Acute radiation exposure induces apoptosis of tissues in the hematopoietic, digestive, cutaneous, cardiovascular and nervous systems; extensive apoptosis of these tissues ultimately leads to acute radiation syndrome. A novel strategy for developing radiation countermeasures has been to imitate the genetic mechanisms acquired by radiation-resistant tumors. Two mechanisms that underlie this ability of tumor cells are the p53 and NF-κB pathways. The loss of p53 function results in the inactivation of pro-apoptotic control mechanisms, while constitutive activation of NF-κB results in the up-regulation of anti-apoptotic genes. Various Toll-like receptor ligands are capable of up regulating the NF-κB pathway, which increases radio-resistance and reduces radiation-induced apoptosis in various tissues. Several Toll-like receptor ligands have been patented and are currently under development as radiation countermeasures for acute radiation syndrome. Ongoing studies suggest that a few of these attractive agents are progressing well along the US FDA approval pathway to become radiation countermeasures.

Patents for Toll-like receptor ligands as radiation countermeasures for acute radiation syndrome

PubMed Central

Singh, Vijay K; Pollard, Harvey B

2015-01-01

Acute radiation exposure induces apoptosis of tissues in the hematopoietic, digestive, cutaneous, cardiovascular and nervous systems; extensive apoptosis of these tissues ultimately leads to acute radiation syndrome. A novel strategy for developing radiation countermeasures has been to imitate the genetic mechanisms acquired by radiation-resistant tumors. Two mechanisms that underlie this ability of tumor cells are the p53 and NF-κB pathways. The loss of p53 function results in the inactivation of pro-apoptotic control mechanisms, while constitutive activation of NF-κB results in the up-regulation of anti-apoptotic genes. Various Toll-like receptor ligands are capable of up regulating the NF-κB pathway, which increases radio-resistance and reduces radiation-induced apoptosis in various tissues. Several Toll-like receptor ligands have been patented and are currently under development as radiation countermeasures for acute radiation syndrome. Ongoing studies suggest that a few of these attractive agents are progressing well along the US FDA approval pathway to become radiation countermeasures. PMID:26135043

Experimental adaptation of human echovirus 11 to ultraviolet radiation leads to resistance to disinfection and ribavirin

PubMed Central

Carratalà, Anna; Shim, Hyunjin; Zhong, Qingxia; Bachmann, Virginie; Jensen, Jeffrey D

2017-01-01

Abstract Ultraviolet light in the UVC range is a commonly used disinfectant to control viruses in clinical settings and water treatment. However, it is currently unknown whether human viral pathogens may develop resistance to such stressor. Here, we investigate the adaptation of an enteric pathogen, human echovirus 11, to disinfection by UVC, and characterized the underlying phenotypic and genotypic changes. Repeated exposure to UVC lead to a reduction in the UVC inactivation rate of approximately 15 per cent compared to that of the wild-type and the control populations. Time-series next-generation sequencing data revealed that this adaptation to UVC was accompanied by a decrease in the virus mutation rate. The inactivation efficiency of UVC was additionally compromised by a shift from first-order to biphasic inactivation kinetics, a form of ‘viral persistence’ present in the UVC resistant and control populations. Importantly, populations with biphasic inactivation kinetics also exhibited resistance to ribavirin, an antiviral drug that, as UVC, interferes with the viral replication. Overall, the ability of echovirus 11 to adapt to UVC is limited, but it may have relevant consequences for disinfection in clinical settings and water treatment plants. PMID:29225923

Effectiveness of solar disinfection using batch reactors with non-imaging aluminium reflectors under real conditions: Natural well-water and solar light.

PubMed

Navntoft, C; Ubomba-Jaswa, E; McGuigan, K G; Fernández-Ibáñez, P

2008-12-11

Inactivation kinetics are reported for suspensions of Escherichia coli in well-water using compound parabolic collector (CPC) mirrors to enhance the efficiency of solar disinfection (SODIS) for batch reactors under real, solar radiation (cloudy and cloudless) conditions. On clear days, the system with CPC reflectors achieved complete inactivation (more than 5-log unit reduction in bacterial population to below the detection limit of 4CFU/mL) one hour sooner than the system fitted with no CPC. On cloudy days, only systems fitted with CPCs achieved complete inactivation. Degradation of the mirrors under field conditions was also evaluated. The reflectivity of CPC systems that had been in use outdoors for at least 3 years deteriorated in a non-homogeneous fashion. Reflectivity values for these older systems were found to vary between 27% and 72% compared to uniform values of 87% for new CPC systems. The use of CPC has been proven to be a good technological enhancement to inactivate bacteria under real conditions in clear and cloudy days. A comparison between enhancing optics and thermal effect is also discussed.

UVA Causes Dual Inactivation of Cathepsin B and L Underlying Lysosomal Dysfunction in Human Dermal Fibroblasts

PubMed Central

Lamore, Sarah D.; Wondrak, Georg T.

2013-01-01

Cutaneous exposure to chronic solar UVA-radiation is a causative factor in photocarcinogenesis and photoaging. Recently, we have identified the thiol-dependent cysteine-protease cathepsin B as a novel UVA-target undergoing photo-oxidative inactivation upstream of autophagic-lysosomal dysfunction in fibroblasts. In this study, we examined UVA effects on a wider range of cathepsins and explored the occurrence of UVA-induced cathepsin inactivation in other cultured skin cell types. In dermal fibroblasts, chronic exposure to non-cytotoxic doses of UVA caused pronounced inactivation of the lysosomal cysteine-proteases cathepsin B and L, effects not observed in primary keratinocytes and occurring only to a minor extent in primary melanocytes. In order to determine if UVA-induced lysosomal impairment requires single or dual inactivation of cathepsin B and/or L, we used a genetic approach (siRNA) to selectively downregulate enzymatic activity of these target cathepsins. Monitoring an established set of protein markers (including LAMP1, LC3-II, and p62) and cell ultrastructural changes detected by electron microscopy, we observed that only dual genetic antagonism (targeting both CTSB and CTSL expression) could mimic UVA-induced autophagic-lysosomal alterations, whereas single knockdown (targeting CTSB or CTSL only) did not display ‘UVA-mimetic’ effects failing to reproduce the UVA-induced phenotype. Taken together, our data demonstrate that chronic UVA inhibits both cathepsin B and L enzymatic activity and that dual inactivation of both enzymes is a causative factor underlying UVA-induced impairment of lysosomal function in dermal fibroblasts. PMID:23603447

Validating the Inactivation Effectiveness of Chemicals on Ebola Virus.

PubMed

Haddock, Elaine; Feldmann, Friederike

2017-01-01

While viruses such as Ebola virus must be handled in high-containment laboratories, there remains the need to process virus-infected samples for downstream research testing. This processing often includes removal to lower containment areas and therefore requires assurance of complete viral inactivation within the sample before removal from high-containment. Here we describe methods for the removal of chemical reagents used in inactivation procedures, allowing for validation of the effectiveness of various inactivation protocols.

Identification of irradiated refrigerated pork with the DNA comet assay

NASA Astrophysics Data System (ADS)

Araújo, M. M.; Marin-Huachaca, N. S.; Mancini-Filho, J.; Delincée, H.; Villavicencio, A. L. C. H.

2004-09-01

Food irradiation can contribute to a safer and more plentiful food supply by inactivating pathogens, eradicating pests and by extending shelf-life. Particularly in the case of pork meat, this process could be a useful way to inactivate harmful parasites such as Trichinella and Taenia solium. Ionizing radiation causes damage to the DNA of the cells (e.g. strand breaks), which can be used to detect irradiated food. Microelectrophoresis of single cells (``Comet Assay'') is a simple and rapid test for DNA damage and can be used over a wide dose range and for a variety of products. Refrigerated pork meat was irradiated with a 60Co source, Gammacell 220 (A.E.C.L.) installed in IPEN (Sa~o Paulo, Brazil). The doses given were 0, 1.5, 3.0 and 4.5kGy for refrigerated samples. Immediately after irradiation the samples were returned to the refrigerator (6°C). Samples were kept in the refrigerator after irradiation. Pork meat was analyzed 1, 8 and 10 days after irradiation using the DNA ``Comet Assay''. This method showed to be an inexpensive and rapid technique for qualitative detection of irradiation treatment.

Ultraviolet germicidal efficacy as a function of pulsed radiation parameters studied by spore film dosimetry.

PubMed

Bauer, Stefan; Holtschmidt, Hans; Ott, Günter

2018-01-01

Disinfection by pulsed ultraviolet (UV) radiation is a commonly used method, e.g. in industry or medicine and can be carried out either with lasers or broadband UV radiation sources. Detrimental effects to biological materials depending on parameters such as pulse duration τ or pulse repetition frequency f p are well-understood for pulsed coherent UV radiation, however, relatively little is known for its incoherent variant. Therefore, within this work, it is the first time that disinfection rates of pulsed and continuous (cw) incoherent UV radiation studied by means of spore film dosimetry are presented, compared with each other, and in a second step further investigated regarding two pulse parameters. After analyzing the dynamic range of the Bacillus subtilis spore films with variable cw radiant exposures H=5-100Jm -2 a validation of the Bunsen-Roscoe law revealed its restricted applicability and a 28% enhanced detrimental effect of pulsed compared to cw incoherent UV radiation. A radiant exposure H=50Jm -2 and an irradiance E=0.5Wm -2 were found to be suitable parameters for an analysis of the disinfection rate as a function of τ=0.5-10ms and f p =25-500Hz unveiling that shorter pulses and lower frequencies inactivate more spores. Finally, the number of applied pulses as well as the experiment time were considered with regard to spore film disinfection. Copyright © 2017 Elsevier B.V. All rights reserved.

Disinfection of an advanced primary effluent using peracetic acid or ultraviolet radiation for its reuse in public services.

PubMed

Julio, Flores R; Hilario, Terres-Peña; Mabel, Vaca M; Raymundo, López C; Arturo, Lizardi-Ramos; Ma Neftalí, Rojas-Valencia

2015-03-01

The disinfection of a continuous flow of an effluent from an advanced primary treatment (coagulation-flocculation-sedimentation) with or without posterior filtration, using either peracetic acid (PAA) or ultraviolet (UV) radiation was studied. We aimed to obtain bacteriological quality to comply with the microbiological standard established in the Mexican regulations for treated wastewater reuse (NOM-003-SEMARNAT-1997), i.e., less than 240 MPN (most probable number) FC/100 mL. The concentrations of PAA were 10, 15, and 20 mg/L, with contact times of 10, and 15 min. Fecal coliforms (FC) inactivation ranged from 0.93 up to 6.4 log units, and in all cases it reached the limits set by the mentioned regulation. Water quality influenced the PAA disinfection effectiveness. An efficiency of 91% was achieved for the unfiltered effluent, as compared to 99% when wastewater was filtered. UV radiation was applied to wastewater flows of 21, 30 and 39 L/min, with dosages from 1 to 6 mJ/cm². This treatment did not achieve the bacteriological quality required for treated wastewater reuse, since the best inactivation of FC was 1.62 log units, for a flow of 21 L/min of filtered wastewater and a UV dosage of 5.6 mJ/cm².

Electron beam radiation of dried fruits and nuts to reduce yeast and mold bioburden.

PubMed

Ic, Erhan; Kottapalli, Bala; Maxim, Joseph; Pillai, Suresh D

2007-04-01

Dried fruits and nuts make up a significant portion of the commodities traded globally, and the presence of yeasts and molds on dried fruits and nuts can be a public health risk because of the potential for exposure to toxigenic fungi. Since current postharvest treatment technologies are rather limited for dried fruits and nuts, electron beam (E-beam) radiation experiments were performed to determine the doses required to reduce the yeast and mold bioburden of raisins, walnuts, and dates. The indigenous yeast and mold bioburden on a select number of commodities sold at retail ranged from 10(2) to 10(3) CFU/g. E-beam inactivation kinetics based on the linear model suggest that the decimal reduction dose required to eliminate 90% of the microbial population (D10-value) of these indigenous fungal populations ranges from 1.09 to 1.59 kGy. Some samples, however, exhibited inactivation kinetics that were better modeled by a quadratic model. The results indicate that different commodities can contain molds and yeasts of varying resistance to ionizing radiation. It is thus essential for the dried fruit and nut industry to determine empirically the minimum E-beam dose that is capable of reducing or eliminating the bioburden of yeasts and molds in their specific commodities.

A Standard Method To Inactivate Bacillus anthracis Spores to Sterility via Gamma Irradiation

PubMed Central

Cote, Christopher K.; Buhr, Tony; Bernhards, Casey B.; Bohmke, Matthew D.; Calm, Alena M.; Esteban-Trexler, Josephine S.; Hunter, Melissa; Katoski, Sarah E.; Kennihan, Neil; Klimko, Christopher P.; Miller, Jeremy A.; Minter, Zachary A.; Pfarr, Jerry W.; Prugh, Amber M.; Quirk, Avery V.; Rivers, Bryan A.; Shea, April A.; Shoe, Jennifer L.; Sickler, Todd M.; Young, Alice A.; Fetterer, David P.; Welkos, Susan L.; McPherson, Derrell; Fountain, Augustus W.

2018-01-01

ABSTRACT In 2015, a laboratory of the United States Department of Defense (DoD) inadvertently shipped preparations of gamma-irradiated spores of Bacillus anthracis that contained live spores. In response, a systematic evidence-based method for preparing, concentrating, irradiating, and verifying the inactivation of spore materials was developed. We demonstrate the consistency of spore preparations across multiple biological replicates and show that two different DoD institutions independently obtained comparable dose-inactivation curves for a monodisperse suspension of B. anthracis spores containing 3 × 1010 CFU. Spore preparations from three different institutions and three strain backgrounds yielded similar decimal reduction (D10) values and irradiation doses required to ensure sterility (DSAL) to the point at which the probability of detecting a viable spore is 10−6. Furthermore, spores of a genetically tagged strain of B. anthracis strain Sterne were used to show that high densities of dead spores suppress the recovery of viable spores. Together, we present an integrated method for preparing, irradiating, and verifying the inactivation of spores of B. anthracis for use as standard reagents for testing and evaluating detection and diagnostic devices and techniques. IMPORTANCE The inadvertent shipment by a U.S. Department of Defense (DoD) laboratory of live Bacillus anthracis (anthrax) spores to U.S. and international destinations revealed the need to standardize inactivation methods for materials derived from biological select agents and toxins (BSAT) and for the development of evidence-based methods to prevent the recurrence of such an event. Following a retrospective analysis of the procedures previously employed to generate inactivated B. anthracis spores, a study was commissioned by the DoD to provide data required to support the production of inactivated spores for the biodefense community. The results of this work are presented in this publication, which details the method by which spores can be prepared, irradiated, and tested, such that the chance of finding residual living spores in any given preparation is 1/1,000,000. These irradiated spores are used to test equipment and methods for the detection of agents of biological warfare and bioterrorism. PMID:29654186

Fate of Earth Microbes on Mars: UV Radiation Effects

NASA Technical Reports Server (NTRS)

Cockell, Charles

2000-01-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

Fate of Earth Microbes on Mars -- UV Radiation Effects

NASA Technical Reports Server (NTRS)

Cockell, Charles

2000-01-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

The impact of solar UV radiation on the early biosphere

NASA Astrophysics Data System (ADS)

Horneck, G.

2007-08-01

Stratospheric ozone, photochemically produced from atmospheric oxygen, is a protective filter of the Earth's atmosphere by absorbing most of the biologically harmful UV radiation of our sun in the UV-C (190-280 nm) and short wavelength-region of the UV-B (280-315 nm). Numerous lines of isotopic and geologic evidence suggest that the Archean atmosphere was essentially anoxic. As a result the column abundance of ozone would have been insufficient to affect the surface UV radiation environment. Thus, as well as UV-B radiation, UV-C radiation would have penetrated to the Earth's surface with its associated biological consequences. The history of this ultraviolet stress for the early Earth has been determined from theoretical data and data obtained in Earth orbit on the inactivation of Bacillus subtilis spores under a simulated ozone layer of different thicknesses. Although the UV-C and UV-B regions contribute only 2 % of the entire solar extraterrestrial irradiance, photobiological experiments in space have demonstrated a high mutagenicity and lethality of this UV range to living organisms. The reason for these severe effects of extraterrestrial solar UV radiation - compared to conditions on present-day Earth - lies in the absorption characteristics of the DNA, which is the decisive target for inactivation and mutation induction at this UV range. Being a strong mutagen, UV-radiation is considered as a powerful promoter of biological evolution on the one hand, one the other hand, it may have deleterious consequences to individual cells and organisms, e.g. by causing inactivation, mutations or cancer induction. In response to potential harmful effects of environmental UV radiation, life on Earth has developed several strategies of survival, either avoiding exposure to UV radiation or restoring UV damage. Mechanisms of avoidance of exposure to UV radiation include (i) moving away from the UV radiation into shadowed areas, which requires the development of UV radiation sensing mechanisms; (ii) application of external shielding, such as covering by mud, sand or rock material; (iii) development of intrinsic UV screening pigments, such as tanning, inductive flavonoid production of plants, intracellular mycosporin production in cyanobacteria, (iv) accumulation of antioxidants and quenching substances. However, if UV damage has been induced - in spite of all avoidance efforts, organisms may restore their functionality by numerous repair processes. Repair pathways of a rich diversity and functional universality include (i) direct repair with the reversal of photochemical abnormalities, e.g. in the DNA; (ii) recombination repair removing the UV-induced abnormality by homologous recombination; and (iii) excision repair, where the section of the DNA strand containing the abnormality is removed and a repair patch is synthesized using the intact strand as a template. In addition to efficient repair systems for radiation-induced DNA injury, life has developed a variety of defense mechanisms, such as the increase in the production of stress proteins and the activation of the immune defence system. Some of these capacities have certainly already been evolved in the early biosphere, when it was exposed to the extended UV-spectrum of the sun. Only since the early Proterozoic, due to a rapid rise in the atmospheric oxygen concentration and consequently a photochemical built up of the stratospheric ozone layer, a more moderate UV radiation climate prevailed with wavelengths shorter than 295 nm being effectively cut off.

Detoxification of Salmonella typhimurium lipopolysaccharide by ionizing radiation.

PubMed

Previte, J J; Chang, Y; el-Bisi, H M

1967-05-01

The efficiency of ionizing radiation in detoxifying the lethal determinant(s) of the lipopolysaccharide (LPS) of Salmonella typhimurium, S. enteritidis, and Escherichia coli in aqueous solution and associated with heat-killed S. typhimurium cells in suspension decreased with doses above 1 Mrad. The 50% end point of inactivation was more than 7.0 Mrad for heat-killed salmonellae and 4.8, 4.5, and 1.0 Mrad for the LPS of S. typhimurium, S. enteritidis, and E. coli, respectively. After exposure to 20 Mrad, S. typhimurium LPS retained a small portion of its lethal properties although the ld(50) was much greater than 9.5 mg per 20-g mouse. However, at -184 C, no inactivation of the lethal determinant(s) occurred after exposure to as much as 20 Mrad. This demonstrated the significance of the indirect effect and the mobility and formation of free radicals. At 22 C, the optical density at 400 mmu increased and the pH decreased with increasing radiation dose, but no qualitative changes were observed in the infrared spectrum. No change was observed in the pyrogenicity of S. typhimurium LPS; a slight decrease in antigenicity was revealed when 6 days, but not when 1 day, elapsed between vaccination and challenge in the mouse protection test. The results were interpreted as evidence of the existence of two or more lethal and antigenic determinants. The differential effect of radiation on these properties and on the pyrogenic component(s) probably are indicative of separate functional sites for lethal, antigenic, and pyrogenic activities.

CRYPTOSPORIDIUM LOG INACTIVATION CALCULATION METHODS

EPA Science Inventory

Appendix O of the Surface Water Treatment Rule (SWTR) Guidance Manual introduces the CeffT10 (i.e., reaction zone outlet C value and T10 time) method for calculating ozone CT value and Giardia and virus log inactivation. The LT2ESWTR Pre-proposal Draft Regulatory Language for St...

Effect of ohmic heating of soymilk on urease inactivation and kinetic analysis in holding time.

PubMed

Li, Fa-De; Chen, Chen; Ren, Jie; Wang, Ranran; Wu, Peng

2015-02-01

To verify the effect of the ohmic heating on the urease activity in the soymilk, the ohmic heating methods with the different electrical field conditions (the frequency and the voltage ranging from 50 to 10 kHz and from 160 to 220 V, respectively) were employed. The results showed that if the value of the urease activity measured with the quantitative spectrophotometry method was lower than 16.8 IU, the urease activity measured with the qualitative method was negative. The urease activity of the sample ohmically heated was significantly lower than that of the sample conventionally heated (P < 0.01) at the same target temperature. It was concluded that the electrical field enhanced the urease inactivation. In addition, the inactivation kinetics of the urease in the soymilk could be described with a biphasic model during holding time at a target temperature. Thus, it was concluded that the urease in the soymilk would contain 2 isoenzymes, one is the thermolabile fraction, the other the thermostable fraction, and that the thermostable isoenzyme could not be completely inactivated when the holding time increased, whether the soymilk was cooked with the conventional method or with the ohmic heating method. Therefore, the electric field had no effect on the inactivation of the thermostable isoenzyme of the urease. © 2015 Institute of Food Technologists®

Ultraviolet disinfection of potable water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfe, R.L.

Because of upcoming surface and groundwater regulations regarding the control of microbiological and chemical contaminants, there is a need to evaluate the feasibility and effectiveness of ultraviolet (UV) radiation for primary disinfection of potable water supplies. Data is presented on microbicidal wavelengths of UV and distribution of energy output for low and medium-pressure arc lamps. Both systems were found to perform equally well for inactivating microorganisms, but each had distinct advantages in different applications. Approximate dosages for 90% inactivation of selected microorganisms by UV is presented in a table. Cost analysis for disinfection is presented in two tables as wellmore » as the advantages and disadvantages of UV disinfection. 38 refs.« less

The Protein/Peptide Direct Virus Inactivation During Chromatographic Process: Developing Approaches.

PubMed

Volkov, Georgii L; Havryliuk, Sergiy P; Krasnobryzha, Ievgenia M; Havryliuk, Olena S

2017-01-01

Virus clearance is required for pharmaceutical preparations derived from animal or human sources such as blood products, vaccines, recombinant proteins produced in mammalian cell lines, etc. High cost and substantial protein losses during virus inactivation are significant problems for protein/peptide manufacturing. The goal of this project was to develop a method to perform virus inactivation in a course of protein chromatographic purification. Another goal was to show that the chromatographic adsorbent can serve as reliable "sieva" for mechanical washing away of infecting viruses. Using chromatographic, photometric, IFA, and RT-PCR approaches, it was discovered that high temperature-depending dynamic capacity of adsorbent allowed to perform a virus inactivation directly in a chromatographic column by solvent/detergent treatment. The peptide/protein biological activity was completely preserved. Using this new approach enveloped and nonenveloped viruses were effectively removed protein preparation. In addition, it was shown that RT-PCR method demonstrates more precise and reproducible results and robust properties for assessment of virus reduction than virus titer followed by infectivity studies. Presented method allowed to obtain the factor of virus concentration decrease (FVD) values that were higher than those provided by known technologies and was sufficient for a full inactivation of viruses. The method is recommended to use in pharmaceutical industry.

Selective Destruction Of Cells Infected With The Human Immunodeficiency Virus

DOEpatents

Keener, William K.; Ward, Thomas E.

2006-03-28

Compositions and methods for selectively killing a cell containing a viral protease are disclosed. The composition is a varient of a protein synthesis inactivating toxin wherein a viral protease cleavage site is interposed between the A and B chains. The variant of the type II ribosome-inactivating protein is activated by digestion of the viral protease cleavage site by the specific viral protease. The activated ribosome-inactivating protein then kills the cell by inactivating cellular ribosomes. A preferred embodiment of the invention is specific for human immunodeficiency virus (HIV) and uses ricin as the ribosome-inactivating protein. In another preferred embodiment of the invention, the variant of the ribosome-inactivating protein is modified by attachment of one or more hydrophobic agents. The hydrophobic agent facilitates entry of the variant of the ribosome-inactivating protein into cells and can lead to incorporation of the ribosome-inactivating protein into viral particles. Still another preferred embodiment of the invention includes a targeting moiety attached to the variants of the ribosome-inactivating protein to target the agent to HIV infectable cells.

Selective destruction of cells infected with human immunodeficiency virus

DOEpatents

Keener, William K.; Ward, Thomas E.

2003-09-30

Compositions and methods for selectively killing a cell containing a viral protease are disclosed. The composition is a variant of a protein synthesis inactivating toxin wherein a viral protease cleavage site is interposed between the A and B chains. The variant of the type II ribosome-inactivating protein is activated by digestion of the viral protease cleavage site by the specific viral protease. The activated ribosome-inactivating protein then kills the cell by inactivating cellular ribosomes. A preferred embodiment of the invention is specific for human immunodeficiency virus (HIV) and uses ricin as the ribosome-inactivating protein. In another preferred embodiment of the invention, the variant of the ribosome-inactivating protein is modified by attachment of one or more hydrophobic agents. The hydrophobic agent facilitates entry of the variant of the ribosome-inactivating protein into cells and can lead to incorporation of the ribosome-inactivating protein into viral particles. Still another preferred embodiment of the invention includes a targeting moiety attached to the variants of the ribosome-inactivating protein to target the agent to HIV infectable cells.

Inactivation of Uropathogenic Escherichia coli in Ground Chicken Meat Using High Pressure Processing and Gamma Radiation, and in Purge and Chicken Meat Surfaces by Ultraviolet Light.

PubMed

Sommers, Christopher H; Scullen, O J; Sheen, Shiowshuh

2016-01-01

Extraintestinal pathogenic Escherichia coli, including uropathogenic E. coli (UPEC), are common contaminants in poultry meat and may cause urinary tract infections after colonization of the gastrointestinal tract and transfer of contaminated feces to the urethra. Three non-thermal processing technologies used to improve the safety and shelf-life of both human and pet foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). Multi-isolate cocktails of UPEC were inoculated into ground chicken which was then treated with HPP (4°C, 0-25 min) at 300, 400, or 500 MPa. HPP D10, the processing conditions needed to inactivate 1 log of UPEC, was 30.6, 8.37, and 4.43 min at 300, 400, and 500 MPa, respectively. When the UPEC was inoculated into ground chicken and gamma irradiated (4 and -20°C) the GR D10 were 0.28 and 0.36 kGy, respectively. The UV-C D10 of UPEC in chicken suspended in exudate and placed on stainless steel and plastic food contact surfaces ranged from 11.4 to 12.9 mJ/cm(2). UV-C inactivated ca. 0.6 log of UPEC on chicken breast meat. These results indicate that existing non-thermal processing technologies such as HPP, GR, and UV-C can significantly reduce UPEC levels in poultry meat or exudate and provide safer poultry products for at-risk consumers.

The Efficiency of UVC Radiation in the Inactivation of
Listeria monocytogenes on Beef-Agar Food Models.

PubMed

Hamidi-Oskouei, Amir M; James, Christian; James, Stephen

2015-06-01

The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light.

The Efficiency of UVC Radiation in the Inactivation of
Listeria monocytogenes on Beef-Agar Food Models

PubMed Central

James, Christian; James, Stephen

2015-01-01

Summary The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light. PMID:27904353

Virus inactivation by silver doped titanium dioxide nanoparticles for drinking water treatment.

PubMed

Liga, Michael V; Bryant, Erika L; Colvin, Vicki L; Li, Qilin

2011-01-01

Photocatalytic inactivation of viruses and other microorganisms is a promising technology that has been increasingly utilized in recent years. In this study, photocatalytic silver doped titanium dioxide nanoparticles (nAg/TiO(2)) were investigated for their capability of inactivating Bacteriophage MS2 in aqueous media. Nano-sized Ag deposits were formed on two commercial TiO(2) nanopowders using a photochemical reduction method. The MS2 inactivation kinetics of nAg/TiO(2) was compared to the base TiO(2) material and silver ions leached from the catalyst. The inactivation rate of MS2 was enhanced by more than 5 fold depending on the base TiO(2) material, and the inactivation efficiency increased with increasing silver content. The increased production of hydroxyl free radicals was found to be responsible for the enhanced viral inactivation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Thermal Inactivation of avian influenza virus in poultry litter as a method to decontaminate poultry houses.

PubMed

Stephens, Christopher B; Spackman, Erica

2017-09-15

Removal of contaminated material from a poultry house during recovery from an avian influenza virus (AIV) outbreak is costly and labor intensive. Because AIV is not environmentally stable, heating poultry houses may provide an alternative disinfection method. The objective was to determine the time necessary to inactivate AIV in poultry litter at temperatures achievable in a poultry house. Low pathogenic (LP) AIV inactivation was evaluated between 10.0°-48.9°C, at ∼5.5°C intervals and highly pathogenic (HP) AIV inactivation was evaluated between 10.0°-43.3°C, at ∼11°C intervals. Samples were collected at numerous time points for each temperature. Virus isolation in embryonating chicken eggs was conducted to determine if viable virus was present. Each sample was also tested by real-time RT-PCR. Low pathogenicity AIV was inactivated at 1day at 26.7°C or above. At 10.0, 15.6 and 21.1°C, inactivation times increased to 2-5days. Highly pathogenic AIV followed a similar trend; the virus was inactivated after 1day at 43.3°C and 32.2°C, and required 2 and 5days for inactivation at 21.1°C and 10.0°C respectively. While low pathogenicity AIV appeared to be inactivated at a lower temperature than high pathogenicity AIV, this was not due to any difference in the strains, but due to fewer temperature points being evaluated for high pathogenicity. Endpoints for detection by real-time RT-PCR were not found even weeks after the virus was inactivated. This provides a guideline for the time required, at specific temperatures to inactivate AIV in poultry litter and likely on surfaces within the house. Heat treatment will provide an added level of safety to personnel and against further spread by eliminating infectious virus prior to cleaning a house. Published by Elsevier B.V.

Experimental Study on Inactivation of Bacterial Endotoxin by Using Dielectric Barrier Discharge

NASA Astrophysics Data System (ADS)

Shi, Xingmin; Li, Yaxi; Zhang, Guanjun; Ma, Yue; Shao, Xianjun

2011-12-01

The low-temperature plasma (LTP) generated by dielectric barrier discharge (DBD) was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentrations of bacterial endotoxin (1 EU/mL, 0.5 EU/mL and 0.25 EU/mL) were treated by LTP for different time (20 s, 40 s and 60 s). Tachypleus amebocyte lysate (TAL) method was employed to detect the concentration variation of bacterial endotoxin before and after the plasma treatment, and endotoxic shock mice model was used to evaluate the inactivation effects of LTP on endotoxin for further study. Experimental results demonstrated that, DBD plasma can inactivate the bacterial endotoxin quickly and effectively, and when the LTP treatment time was increased, the concentrations of bacterial endotoxin decreased gradually (after 60 s plasma treatment, its inactivation effect was beyond the Chinese pharmacopoeia standard), and the average survival time of mice gradually extended. The possible inactivation mechanisms are proposed to be related to reactive oxygen species (ROSs).

Inactivation of human norovirus and Tulane virus in simple mediums and fresh whole strawberries by ionizing radiation

USDA-ARS?s Scientific Manuscript database

Human norovirus (NoV) is a major cause of fresh produce associated outbreaks and human NoV in irrigation water can potentially lead to viral internalization in fresh produce. Therefore, there is a need to develop novel intervention strategies to target internalized viral pathogens while maintainin...

CLAY MINERALS PROTECT BACTERIOPHAGE PBS1 OF BACILLUS SUBTILIS AGAINST INACTIVATION AND LOSS OF TRANSDUCING ABILITY BY UV RADIATION. (R826107)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steven A. Belinsky, PhD

The molecular mechanisms that result in the elevated risk for lung cancer associated with exposure to radiation have not been well characterized. Workers from the MAYAK nuclear enterprise are an ideal cohort in which to study the molecular epidemiology of cancer associated with radiation exposure and to identify the genes targeted for inactivation that in turn affect individual risk for radiation-induced lung cancer. Epidemiology studies of the MAYAK cohort indicate a significantly higher frequency for adenocarcinoma and squamous cell carcinoma (SCC) in workers than in a control population and a strong correlation between these tumor types and plutonium exposure. Twomore » hypotheses will be evaluated through the proposed studies. First, radiation exposure targets specific genes for inactivation by promoter methylation. This hypothesis is supported by our recent studies with the MAYAK population that demonstrated the targeting of the p16 gene for inactivation by promoter methylation in adenocarcinomas from workers (1). Second, genes inactivated in tumors can serve as biomarkers for lung cancer risk in a cancer-free population of workers exposed to plutonium. Support for this hypothesis is based on exciting preliminary results of our nested, case-control study of persons from the Colorado cohort. In that study, a panel of methylation markers for predicting lung cancer risk is being evaluated in sputum samples from incident lung cancer cases and controls. The first hypothesis will be tested by determining the prevalence for promoter hypermethylation of a panel of genes shown to play a critical role in the development of either adenocarcinoma and/or SCC associated with tobacco. Our initial studies on adenocarcinoma in MAYAK workers will be extended to evaluate methylation of the PAX5 {alpha}, PAX5 {beta}, H-cadherin, GATA5, and bone morphogenesis 3B (BMP3B) genes in the original sample set described under Preliminary studies. In addition, studies will be initiated in SCC from workers and controls to identify genes targeted for inactivation by plutonium in this other common histologic form of lung cancer. We will examine methylation of the p16, O{sup 6}-methylguanine-DNA methyl-transferase (MGMT), and death associated protein kinase genes ([DAP-K], evaluated previously in adenocarcinomas) as well as the new genes being assessed in the adenocarcinomas. The second hypothesis will be tested in a cross-sectional study of cancer-free workers exposed to plutonium and an unexposed population. A cohort of 700 cancer-free workers and 700 unexposed persons is being assembled, exposures are being defined, and induced sputum collected at initial entry into the study and approximately 1-year later. Exposed and unexposed persons will be matched by 5-year age intervals and smoking status (current and former). The frequency for methylation of four genes that show the greatest difference in prevalence in tumors from workers and controls will be determined in exfoliated cells within sputum. These studies will extend those in primary tumors to determine whether difference in prevalence for individual or multiple genes are detected in sputum samples from high-risk subjects exposed to plutonium. Follow-up of this cohort offers the opportunity to validate these endpoints and future biomarkers as true markers for lung cancer risk.« less

[Effect of NF-κB activation on the radiation response of esophageal cancer cells].

PubMed

Li, Baozhong; Chen, Zhaoli; Zhou, Fang; He, Jie

2014-07-01

To investigate the effect of NF-κB activation on radiation response of esophageal carcinoma. The expression of NF-κB was detected in pretreatment and posttreatment specimens of patients with ESCC by immunohistochemistry. Electrophoretic mobility shift assay (EMSA) and Western blot were used to detect the activation of NF-κB in esophageal cancer cell line KYSE150 cells. SN50, a specific NF-κB inhibitor, was applied to inhibit the activation of NF-κB. Clone formation test was used to detect the radiosensitivity of esophageal cancer cells. The median survival time of patients with activated and inactivated NF-κB in the pretreatment specimens were 16 and 19 months, respectively, with a non-significant difference between the two groups (P > 0.05). As to the patients with activated and inactivated NF-κB in posttreatment specimens, the median survival times were 13 and 35 months, respectively, with a significant difference (P < 0.01) between them. Western blot showed that the cytoplasmic expression of NF-κB was reduced with increasing radiation dose at 1.5 and 3 hours after radiation treatment. However, the expression of NF-κB in the cell nuclei was increased under the same condition, showing a trend of increased nucleus/cytoplasm ratio. The clone number in SN50 group was 96.66, 64.66, 76.66 and 10.00 under 0, 2, 4 and 12 Gy irradiation, which demonstrated a significant difference compared with the control groups (P < 0.001). Our results show that activation of NF-κB is induced by radiotherapy. Activation of NF-κB reduces the outcome of radiation treatment of esophageal cancer patients.

Demonstration of the oncogenic potential of Herpes simplex viruses and human cytomegalovirus. [UV radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, F.; Li, J.L.H.

1975-01-01

The following topics are reviewed: transformation of hamster embryo cells by herpes simplex viruses and human cytomegalovirus; the use of uv radiation and photodynamic action to inactivate virus infectivity while retaining the transformation potential of the virus; detection of virus-specific antigens in transformed cells; oncogenicity of HSV- and CMV-transformed cells in vivo; immunological studies of metastases induced by herpes virus-transformed cells; resistance of transformed cells to superinfection; maintenance of the virus genome in the transformed state; and stimulation of cellular DNA synthesis by human cytomegalovirus. (HLW)

Two pathogen reduction technologies--methylene blue plus light and shortwave ultraviolet light--effectively inactivate hepatitis C virus in blood products.

PubMed

Steinmann, Eike; Gravemann, Ute; Friesland, Martina; Doerrbecker, Juliane; Müller, Thomas H; Pietschmann, Thomas; Seltsam, Axel

2013-05-01

Contamination of blood products with hepatitis C virus (HCV) can cause infections resulting in acute and chronic liver diseases. Pathogen reduction methods such as photodynamic treatment with methylene blue (MB) plus visible light as well as irradiation with shortwave ultraviolet (UVC) light were developed to inactivate viruses and other pathogens in plasma and platelet concentrates (PCs), respectively. So far, their inactivation capacities for HCV have only been tested in inactivation studies using model viruses for HCV. Recently, a HCV infection system for the propagation of infectious HCV in cell culture was developed. Inactivation studies were performed with cell culture-derived HCV and bovine viral diarrhea virus (BVDV), a model for HCV. Plasma units or PCs were spiked with high titers of cell culture-grown viruses. After treatment of the blood units with MB plus light (Theraflex MB-Plasma system, MacoPharma) or UVC (Theraflex UV-Platelets system, MacoPharma), residual viral infectivity was assessed using sensitive cell culture systems. HCV was sensitive to inactivation by both pathogen reduction procedures. HCV in plasma was efficiently inactivated by MB plus light below the detection limit already by 1/12 of the full light dose. HCV in PCs was inactivated by UVC irradiation with a reduction factor of more than 5 log. BVDV was less sensitive to the two pathogen reduction methods. Functional assays with human HCV offer an efficient tool to directly assess the inactivation capacity of pathogen reduction procedures. Pathogen reduction technologies such as MB plus light treatment and UVC irradiation have the potential to significantly reduce transfusion-transmitted HCV infections. © 2012 American Association of Blood Banks.

CYP2C19 progress curve analysis and mechanism-based inactivation by three methylenedioxyphenyl compounds.

PubMed

Salminen, Kaisa A; Meyer, Achim; Imming, Peter; Raunio, Hannu

2011-12-01

Several in vitro criteria were used to assess whether three methylenedioxyphenyl (MDP) compounds, the isoquinoline alkaloids bulbocapnine, canadine, and protopine, are mechanism-based inactivators of CYP2C19. The recently reported fluorometric CYP2C19 progress curve analysis approach was applied first to determine whether these alkaloids demonstrate time-dependent inhibition. In this experiment, bulbocapnine, canadine, and protopine displayed time dependence and saturation in their inactivation kinetics with K(I) and k(inact) values of 72.4 ± 14.7 μM and 0.38 ± 0.036 min(-1), 2.1 ± 0.63 μM and 0.18 ± 0.015 min(-1), and 7.1 ± 2.3 μM and 0.24 ± 0.021 min(-1), respectively. Additional studies were performed to determine whether other specific criteria for mechanism-based inactivation were fulfilled: NADPH dependence, irreversibility, and involvement of a catalytic step in the enzyme inactivation. CYP2C19 activity was not significantly restored by dialysis when it had been inactivated by the alkaloids in the presence of a NADPH-regenerating system, and a metabolic-intermediate complex-associated increase in absorbance at approximately 455 nm was observed. In conclusion, the CYP2C19 progress curve analysis method revealed time-dependent inhibition by these alkaloids, and additional experiments confirmed its quasi-irreversible nature. This study revealed that the CYP2C19 progress curve analysis method is useful for identifying novel mechanism-based inactivators and yields a wealth of information in one run. The alkaloids bulbocapnine, canadine, and protopine, present in herbal medicines, are new mechanism-based inactivators and the first MDP compounds exhibiting quasi-irreversible inactivation of CYP2C19.

Ionizing irradiation not only inactivates clonogenic potential in primary normal human diploid lens epithelial cells but also stimulates cell proliferation in a subset of this population.

PubMed

Fujimichi, Yuki; Hamada, Nobuyuki

2014-01-01

Over the past century, ionizing radiation has been known to induce cataracts in the crystalline lens of the eye, but its mechanistic underpinnings remain incompletely understood. This study is the first to report the clonogenic survival of irradiated primary normal human lens epithelial cells and stimulation of its proliferation. Here we used two primary normal human cell strains: HLEC1 lens epithelial cells and WI-38 lung fibroblasts. Both strains were diploid, and a replicative lifespan was shorter in HLEC1 cells. The colony formation assay demonstrated that the clonogenic survival of both strains decreases similarly with increasing doses of X-rays. A difference in the survival between two strains was actually insignificant, although HLEC1 cells had the lower plating efficiency. This indicates that the same dose inactivates the same fraction of clonogenic cells in both strains. Intriguingly, irradiation enlarged the size of clonogenic colonies arising from HLEC1 cells in marked contrast to those from WI-38 cells. Such enhanced proliferation of clonogenic HLEC1 cells was significant at ≥2 Gy, and manifested as increments of ≤2.6 population doublings besides sham-irradiated controls. These results suggest that irradiation of HLEC1 cells not only inactivates clonogenic potential but also stimulates proliferation of surviving uniactivated clonogenic cells. Given that the lens is a closed system, the stimulated proliferation of lens epithelial cells may not be a homeostatic mechanism to compensate for their cell loss, but rather should be regarded as abnormal. This is because these findings are consistent with the early in vivo evidence documenting that irradiation induces excessive proliferation of rabbit lens epithelial cells and that suppression of lens epithelial cell divisions inhibits radiation cataractogenesis in frogs and rats. Thus, our in vitro model will be useful to evaluate the excessive proliferation of primary normal human lens epithelial cells that may underlie radiation cataractogenesis, warranting further investigations.

Second Cancers After Fractionated Radiotherapy: Stochastic Population Dynamics Effects

NASA Technical Reports Server (NTRS)

Sachs, Rainer K.; Shuryak, Igor; Brenner, David; Fakir, Hatim; Hahnfeldt, Philip

2007-01-01

When ionizing radiation is used in cancer therapy it can induce second cancers in nearby organs. Mainly due to longer patient survival times, these second cancers have become of increasing concern. Estimating the risk of solid second cancers involves modeling: because of long latency times, available data is usually for older, obsolescent treatment regimens. Moreover, modeling second cancers gives unique insights into human carcinogenesis, since the therapy involves administering well characterized doses of a well studied carcinogen, followed by long-term monitoring. In addition to putative radiation initiation that produces pre-malignant cells, inactivation (i.e. cell killing), and subsequent cell repopulation by proliferation can be important at the doses relevant to second cancer situations. A recent initiation/inactivation/proliferation (IIP) model characterized quantitatively the observed occurrence of second breast and lung cancers, using a deterministic cell population dynamics approach. To analyze ifradiation-initiated pre-malignant clones become extinct before full repopulation can occur, we here give a stochastic version of this I I model. Combining Monte Carlo simulations with standard solutions for time-inhomogeneous birth-death equations, we show that repeated cycles of inactivation and repopulation, as occur during fractionated radiation therapy, can lead to distributions of pre-malignant cells per patient with variance >> mean, even when pre-malignant clones are Poisson-distributed. Thus fewer patients would be affected, but with a higher probability, than a deterministic model, tracking average pre-malignant cell numbers, would predict. Our results are applied to data on breast cancers after radiotherapy for Hodgkin disease. The stochastic IIP analysis, unlike the deterministic one, indicates: a) initiated, pre-malignant cells can have a growth advantage during repopulation, not just during the longer tumor latency period that follows; b) weekend treatment gaps during radiotherapy, apart from decreasing the probability of eradicating the primary cancer, substantially increase the risk of later second cancers.

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T-7 bacteriophage

NASA Technical Reports Server (NTRS)

Spizizen, J.; Isherwood, J. E.; Taylor, G. R.

1975-01-01

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59)F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T-7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T-7 bacteriophage was observed after exposure to solar ultraviolet radiation.

Development of a method for the characterization and operation of UV-LED for water treatment.

PubMed

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2017-10-01

Tremendous improvements in semiconductor technology have made ultraviolet light-emitting diodes (UV-LEDs) a viable alternative to conventional UV sources for water treatment. A robust and validated experimental protocol for studying the kinetics of microorganism inactivation is key to the further development of UV-LEDs for water treatment. This study proposes a protocol to operate UV-LEDs and control their output as a polychromatic radiation source. In order to systematically develop this protocol, the results of spectral power distribution, radiation profile, and radiant power measurements of a variety of UV-LEDs are presented. A wide range of UV-LEDs was selected for this study, covering various UVA, UVB, and UVC wavelengths, viewing angles from 3.5° to 135°, and a variety of output powers. The effects of operational conditions and measurement techniques were investigated on these UV-LEDs using a specially designed and fabricated setup. Operating conditions, such as the UV-LED electrical current and solder temperature, were found to significantly affect the power and peak wavelength output. The measurement techniques and equipment, including the detector size, detector distance from the UV-LED, and potential reflection from the environment, were shown to influence the results for many of the UV-LEDs. The results obtained from these studies were analyzed and applied to the development of a protocol for UV-LED characterization. This protocol is presented as a guideline that allows the operation and control of UV-LEDs in any structure, as well as accurately measuring the UV-LED output. Such information is essential for performing a reliable UV-LED assessment for the inactivation of microorganisms and for obtaining precise kinetic data. Copyright © 2017 Elsevier Ltd. All rights reserved.

Validation of a simple method for predicting the disinfection performance in a flow-through contactor.

PubMed

Pfeiffer, Valentin; Barbeau, Benoit

2014-02-01

Despite its shortcomings, the T10 method introduced by the United States Environmental Protection Agency (USEPA) in 1989 is currently the method most frequently used in North America to calculate disinfection performance. Other methods (e.g., the Integrated Disinfection Design Framework, IDDF) have been advanced as replacements, and more recently, the USEPA suggested the Extended T10 and Extended CSTR (Continuous Stirred-Tank Reactor) methods to improve the inactivation calculations within ozone contactors. To develop a method that fully considers the hydraulic behavior of the contactor, two models (Plug Flow with Dispersion and N-CSTR) were successfully fitted with five tracer tests results derived from four Water Treatment Plants and a pilot-scale contactor. A new method based on the N-CSTR model was defined as the Partially Segregated (Pseg) method. The predictions from all the methods mentioned were compared under conditions of poor and good hydraulic performance, low and high disinfectant decay, and different levels of inactivation. These methods were also compared with experimental results from a chlorine pilot-scale contactor used for Escherichia coli inactivation. The T10 and Extended T10 methods led to large over- and under-estimations. The Segregated Flow Analysis (used in the IDDF) also considerably overestimated the inactivation under high disinfectant decay. Only the Extended CSTR and Pseg methods produced realistic and conservative predictions in all cases. Finally, a simple implementation procedure of the Pseg method was suggested for calculation of disinfection performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Capsid functions of inactivated human picornaviruses and feline calicivirus.

PubMed

Nuanualsuwan, Suphachai; Cliver, Dean O

2003-01-01

The exceptional stability of enteric viruses probably resides in their capsids. The capsid functions of inactivated human picornaviruses and feline calicivirus (FCV) were determined. Viruses were inactivated by UV, hypochlorite, high temperature (72 degrees C), and physiological temperature (37 degrees C), all of which are pertinent to transmission via food and water. Poliovirus (PV) and hepatitis A virus (HAV) are transmissible via water and food, and FCV is the best available surrogate for the Norwalk-like viruses, which are leading causes of food-borne and waterborne disease in the United States. The capsids of all 37 degrees C-inactivated viruses still protected the viral RNA against RNase, even in the presence of proteinase K, which contrasted with findings with viruses inactivated at 72 degrees C. The loss of ability of the virus to attach to homologous cell receptors was universal, regardless of virus type and inactivation method, except for UV-inactivated HAV, and so virus inactivation was almost always accompanied by the loss of virus attachment. Inactivated HAV and FCV were captured by homologous antibodies. However, inactivated PV type 1 (PV-1) was not captured by homologous antibody and 37 degrees C-inactivated PV-1 was only partially captured. The epitopes on the capsids of HAV and FCV are evidently discrete from the receptor attachment sites, unlike those of PV-1. These findings indicate that the primary target of UV, hypochlorite, and 72 degrees C inactivation is the capsid and that the target of thermal inactivation (37 degrees C versus 72 degrees C) is temperature dependent.

The efficacy of preservation methods to inactivate foodborne viruses.

PubMed

Baert, L; Debevere, J; Uyttendaele, M

2009-05-31

During the last decade an increased incidence of infections and outbreaks attributed to foodborne viruses, in particular noroviruses (NoV), was observed world wide. The awareness of the presence of viruses on food emphasized the need to acquire knowledge regarding the effect of preservation methods upon viruses. Most foodborne viruses cannot be cultured in the laboratory, which hinders studies of their stability in food. Cultivable surrogate viruses, genetically related to the human infecting strains, are taken as a substitute to define inactivation rates. The last years, the number of survival and inactivation studies using various surrogate viruses increased. In this review, state-of-the-art information regarding the efficacy of preservation methods to reduce the level of viruses on food is compiled. In the first place, the effect of preservation methods establishing microbial growth inhibition (chilling, freezing, acidification, reduced water activity and modified atmosphere packaging) upon foodborne viruses is described. Secondly, the use of preservation methods establishing microbial inactivation such as heat treatment, high hydrostatic pressure processing and irradiation to eliminate viruses is discussed. In the third place, the efficacy of decontamination methods on fresh produce and purification procedures applied on live bivalve shellfish to reduce the viral load is included. These studies indicate that viruses persist well on chilled, acidified, frozen foods and foods packed under modified atmosphere or in dried conditions. Intervention strategies inducing microbial inactivation are required to achieve a 3 log reduction of the level of viruses. Decontamination of fresh produce reduces viruses with a maximum of 1 to 2 log while purification of live bivalves is not adequate to prevent viral outbreaks. It was noted that the effect of a particular food preservation method is dependent upon the virus tested and type of food.

Tendon allograft sterilized by peracetic acid/ethanol combined with gamma irradiation.

PubMed

Zhou, Mo; Zhang, Naili; Liu, Xiaoming; Li, Youchen; Zhang, Yumin; Wang, Xusheng; Li, Baoming; Li, Baoxing

2014-07-01

Research and clinical applications have demonstrated that the effects of tendon allografts are comparable to those of autografts when reconstructing injured tendons or ligaments, but allograft safety remains problematic. Sterilisation could eliminate or decrease the possibility of disease transmission, but current methods seldom achieve satisfactory sterilisation without affecting the mechanical properties of the tendon. Peracetic acid-ethanol in combination with low-dose gamma irradiation (PE-R) would inactivate potential deleterious microorganisms without affecting mechanical and biocompatible properties of tendon allograft. Controlled laboratory design. HIV, PPV, PRV and BVDV inactivation was evaluated. After verifying viral inactivation, the treated tendon allografts were characterised by optical microscopy, scanning electron microscopy and tensile testing, and the cytocompatibility was assessed with an MTT assay and by subcutaneous implantation. Effective and efficient inactivation of HIV, PPV, PRV and BVDV was observed. Histological structure and ultrastructure were unchanged in the treated tendon allograft, which also exhibited comparable biomechanical properties and good biocompatibility. The preliminary results confirmed our hypothesis and demonstrated that the PE-R tendon allograft has significant potential as an alternative to ligament/tendon reconstruction. Tendon allografts have been extensively used in ligament reconstruction and tendon repair. However, current sterilisation methods have various shortcomings, so PE-R has been proposed. This study suggests that PE-R tendon allograft has great potential as an alternative for ligament/tendon reconstruction. Sterilisation has been a great concern for tendon allografts. However, most sterilisation methods cannot inactivate viruses and bacteria without impairing the mechanical properties of the tendon allograft. Peracetic acid/ethanol with gamma irradiation can effectively inactivate viruses and bacteria. Meanwhile, tendon allografts sterilised by this method maintain their physiological tendon structure, biomechanical integrity and good compatibility.

DOUGLAS LEA MEMORIAL LECTURE: From targets to genes: a brief history of radiosensitivity

NASA Astrophysics Data System (ADS)

Steel, G. Gordon

1996-02-01

The biological work of Douglas Lea spanned the period from 1934 to his early death in 1947, and during this short period he made important contributions to the theory of radiation action. He interpreted experimental data relating to the effects of radiation on viruses, bacteria, bean roots, etc in terms of the inactivation of discrete targets, which he identified with cellular genes. He thus laid the foundation of much subsequent research. It is now well recognized that mammalian cells differ substantially in radiosensitivity, especially in the low-dose region of the survival curve. The dependence of radiosensitivity on dose rate has been widely studied; this has practical significance for clinical radiotherapy as well as mechanistic implications. Since Lea's time there have been a number of efforts to describe models that can relate cell killing to radiation dose, dose rate, and track structure. So far these have not led to a comprehensive and widely accepted picture. Microdosimetric considerations lead to the concept of differing severity of lesions induced in DNA. Much is known about the sequence of processes that subsequently lead to cell inactivation: this can be divided into phases of induction, processing, and manifestation. Chromosomal events are currently attracting much attention, as they did in Lea's time. Considerable progress has also been made in identifying genes that control the repair of radiation damage. It has been found that mutation is frequently associated with the loss of a large segment of the genome around the damage site and this will have important implications for interactive processes between particle tracks.

Mutation induction in haploid yeast after split-dose radiation exposure. II. Combination of UV-irradiation and X-rays.

PubMed

Keller, B; Zölzer, F; Kiefer, J

2004-01-01

Split-dose protocols can be used to investigate the kinetics of recovery from radiation damage and to elucidate the mechanisms of cell inactivation and mutation induction. In this study, a haploid strain of the yeast, Saccharomyces cerevisiae, wild-type with regard to radiation sensitivity, was irradiated with 254-nm ultraviolet (UV) light and then exposed to X-rays after incubation for 0-6 hr. The cells were incubated either on nutrient medium or salt agar between the treatments. Loss of reproductive ability and mutation to canavanine resistance were measured. When the X-ray exposure immediately followed UV-irradiation, the X-ray survival curves had the same slope irrespective of the pretreatment, while the X-ray mutation induction curves were changed from linear to linear quadratic with increasing UV fluence. Incubations up to about 3 hr on nutrient medium between the treatments led to synergism with respect to cell inactivation and antagonism with respect to mutation, but after 4-6 hr the two treatments acted independently. Incubation on salt agar did not cause any change in the survival curves, but there was a strong suppression of X-ray-induced mutation with increasing UV fluence. On the basis of these results, we suggest that mutation after combined UV and X-ray exposure is affected not only by the induction and suppression of DNA repair processes, but also by radiation-induced modifications of cell-cycle progression and changes in the expression of the mutant phenotype. Copyright 2004 Wiley-Liss, Inc.

Solar photocatalytic disinfection of agricultural pathogenic fungi (Curvularia sp.) in real urban wastewater.

PubMed

Aguas, Yelitza; Hincapie, Margarita; Fernández-Ibáñez, Pilar; Polo-López, María Inmaculada

2017-12-31

The interest in developing alternative water disinfection methods that increase the access to irrigation water free of pathogens for agricultural purposes is increasing in the last decades. Advanced Oxidation Processes (AOPs) have been demonstrated to be very efficient for the abatement of several kind of pathogens in contaminated water. The purpose of the current study was to evaluate and compare the capability of several solar AOPs for the inactivation of resistant spores of agricultural fungi. Solar photoassisted H 2 O 2 , solar photo-Fenton at acid and near-neutral pH, and solar heterogeneous photocatalysis using TiO 2, with and without H 2 O 2 , have been studied for the inactivation of spores of Curvularia sp., a phytopathogenic fungi worldwide found in soils and crops. Different concentrations of reagents and catalysts were evaluated at bench scale (solar vessel reactors, 200mL) and at pilot plant scale (solar Compound Parabolic Collector-CPC reactor, 20L) under natural solar radiation using distilled water (DW) and real secondary effluents (SE) from a municipal wastewater treatment plant. Inactivation order of Curvularia sp. in distilled water was determined, i.e. TiO 2 /H 2 O 2 /sunlight (100/50mgL -1 )>H 2 O 2 /sunlight (40mgL -1 )>TiO 2 /sunlight (100mgL -1 )>photo-Fenton with 5/10mgL -1 of Fe 2+ /H 2 O 2 at pH3 and near-neutral pH. For the case of SE, at near neutral pH, the most efficient solar process was H 2 O 2 /Solar (60mgL -1 ); nevertheless, the best Curvularia sp. inactivation rate was obtained with photo-Fenton (10/20mgL -1 of Fe 2+ /H 2 O 2 ) requiring a previous water adicification to pH3, within 300 and 210min of solar treatment, respectively. These results show the efficiency of solar AOPs as a feasible option for the inactivation of resistant pathogens in water for crops irrigation, even in the presence of organic matter (average Dissolved Organic Carbon (DOC): 24mgL -1 ), and open a window for future wastewater reclamation and irrigation use. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of the Modified-Hodge test, Carba NP test, and carbapenem inactivation method as screening methods for carbapenemase-producing Enterobacteriaceae.

PubMed

Yamada, Kageto; Kashiwa, Machiko; Arai, Katsumi; Nagano, Noriyuki; Saito, Ryoichi

2016-09-01

We compared three screening methods for carbapenemase-producing Enterobacteriaceae. While the Modified-Hodge test and Carba NP test produced false-negative results for OXA-48-like and mucoid NDM producers, the carbapenem inactivation method (CIM) showed positive results for these isolates. Although the CIM required cultivation time, it is well suited for general clinical laboratories. Copyright © 2016 Elsevier B.V. All rights reserved.

A BAYESIAN METHOD OF ESTIMATING KINETIC PARAMETERS FOR THE INACTIVATION OF CRYPTOSPORIDIUM PARVUM OOCYSTS WITH CHLORINE DIOXIDE AND OZONE

EPA Science Inventory

The main objective of this paper is to use Bayesian methods to estimate the kinetic parameters for the inactivation kinetics of Cryptosporidium parvum oocysts with chlorine dioxide or ozone which are characterized by the delayed Chick-Watson model, i.e., a lag phase or shoulder f...

Inactivation of influenza A virus H1N1 by disinfection process.

PubMed

Jeong, Eun Kyo; Bae, Jung Eun; Kim, In Seop

2010-06-01

Because any patient, health care worker, or visitor is capable of transmitting influenza to susceptible persons within hospitals, hospital-acquired influenza has been a clinical concern. Disinfection and cleaning of medical equipment, surgical instruments, and hospital environment are important measures to prevent transmission of influenza virus from hospitals to individuals. This study was conducted to evaluate the efficacy of disinfection processes, which can be easily operated at hospitals, in inactivating influenza A virus H1N1 (H1N1). The effects of 0.1 mol/L NaOH, 70% ethanol, 70% 1-propanol, solvent/detergent (S/D) using 0.3% tri (n-butyl)-phosphate and 1.0% Triton X-100, heat, and ethylene oxide (EO) treatments in inactivating H1N1 were determined. Inactivation of H1N1 was kinetically determined by the treatment of disinfectants to virus solution. Also, a surface test method, which involved drying an amount of virus on a surface and then applying the inactivation methods for 1 minute of contact time, was used to determine the virucidal activity. H1N1 was completely inactivated to undetectable levels in 1 minute of 70% ethanol, 70% 1-propanol, and solvent/detergent treatments in the surface tests as well as in the suspension tests. H1N1 was completely inactivated in 1 minute of 0.1 mol/L NaOH treatment in the suspension tests and also effectively inactivated in the surface tests with the log reduction factor of 3.7. H1N1 was inactivated to undetectable levels within 5 minutes, 2.5 minutes, and 1 minute of heat treatment at 70, 80, and 90 degrees C, respectively in the suspension tests. Also, H1N1 was completely inactivated by EO treatment in the surface tests. Common disinfectants, heat, and EO tested in this study were effective at inactivating H1N1. These results would be helpful in implementing effective disinfecting measures to prevent hospital-acquired infections. Copyright 2010 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Assessing Photocatalytic Oxidation Using Modified TiO 2 Nanomaterials for Virus Inactivation in Drinking Water: Mechanisms and Application

NASA Astrophysics Data System (ADS)

Liga, Michael Vincent

Photocatalytic oxidation is an alternative water treatment method under consideration for disinfecting water. Chlorine disinfection can form harmful byproducts, and some viruses (e.g. adenoviruses) are resistant to other alternative disinfection methods. Photocatalytic oxidation using nano-sized photocatalytic particles (e.g. TiO2, fullerene) holds promise; however, it is limited by its low efficiency and long required treatment times. This research focuses on improving virus inactivation by photocatalytic oxidation by modifying catalysts for improved activity, by analyzing virus inactivation kinetics, and by elucidating the inactivation mechanisms of adenovirus serotype 2 (AdV2) and bacteriophage MS2. Modifying TiO2 with silver (nAg/TiO2) or silica (SiO2-TiO2) improves the inactivation kinetics of bacteriophage MS2 by a factor of 3-10. nAg/ TiO2 increases hydroxyl radical (HO·) production while SiO2 increases the adsorption of MS2 to TiO 2. These results suggest that modifying the photocatalyst surface to increase contaminant adsorption is an important improvement strategy along with increasing HO· production. The inactivation kinetics of AdV2 by P25 TiO2 is much slower than the MS2 inactivation kinetics and displays a strong shoulder, which is not present in the MS2 kinetics. nAg/TiO2 initially improves the inactivation rate of AdV2. SiO2-TiO2 reduces the AdV2 inactivation kinetics since adsorption is not significantly enhanced, as it is with MS2. Amino-C60 is highly effective for AdV2 inactivation under visible light irradiation, making it a good material for use in solar disinfection systems. The efficacy of amino-fullerene also demonstrates that singlet oxygen is effective for AdV2 inactivation. When exposed to irradiated TiO2, AdV2 hexon proteins are heavily damaged resulting in the release of DNA. DNA damage is also present but may occur after capsids break. With MS2, the host interaction protein is rapidly damaged, but not the coat protein. The kinetics of MS2 inactivation are rapid since it may quickly lose its ability to attach to host cells, while AdV2 kinetics are slower since the entire capsid must undergo heavy oxidation before inactivation occurs. Adenovirus inactivation likely occurs through breaching the capsid followed by radical attack of DNA and core proteins.

Inactivation of possible microorganism food contaminants on packaging foils using nonthermal plasma and hydrogen peroxide

NASA Astrophysics Data System (ADS)

Scholtz, V.; Khun, J.; Soušková, H.; Čeřovský, M.

2015-07-01

The inactivation effect of nonthermal plasma generated in electric discharge burning in air atmosphere with water or hydrogen peroxide aerosol for the application to the microbial decontamination of packaging foils is studied. The microbial inactivation is studied on two bacterial, two yeasts, and two filamentous micromycete species. The inactivation of all contaminating microorganisms becomes on the area of full 8.5 cm in diameter circular sample after short times of several tens of seconds. Described apparatus may present a possible alternative method of microbial decontamination of food packaging material or other thermolabile materials.

Inactivation of possible microorganism food contaminants on packaging foils using nonthermal plasma and hydrogen peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholtz, V., E-mail: Vladimir.Scholtz@vscht.cz; Khun, J.; Soušková, H.

The inactivation effect of nonthermal plasma generated in electric discharge burning in air atmosphere with water or hydrogen peroxide aerosol for the application to the microbial decontamination of packaging foils is studied. The microbial inactivation is studied on two bacterial, two yeasts, and two filamentous micromycete species. The inactivation of all contaminating microorganisms becomes on the area of full 8.5 cm in diameter circular sample after short times of several tens of seconds. Described apparatus may present a possible alternative method of microbial decontamination of food packaging material or other thermolabile materials.

Inactivation of bacteria by electric current in the presence of carbon nanotubes embedded within a polymeric membrane.

PubMed

Zhu, Anna; Liu, Harris K; Long, Feng; Su, Erzheng; Klibanov, Alexander M

2015-01-01

Uniform conductive composite membranes were prepared using a phase inversion method by blending carboxyl-functionalized multi-walled carbon nanotubes (CNTs) with a polysulfone polymer. At 6 % of the embedded CNTs, the membrane pore size measured by transmission electron microscopy (TEM) was approximately 50 nm. Electric current in the presence of the composite membranes markedly inactivated the model pathogenic bacteria Escherichia coli and Staphylococcus aureus, with the extent of bacterial inactivation rising when the current was increased. Over 99.999 % inactivation of both bacteria was observed in deionized water after 40 min at 5 mA direct current (DC); importantly, no appreciable inactivation occurred in the absence of either the electric field or the CNTs within the membranes under otherwise the same conditions. A much lower, although still pronounced, inactivation was seen with alternating current (AC) in a 25 mM NaCl aqueous solution.

Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region.

PubMed

Ndounla, J; Pulgarin, C

2015-11-01

The photo-disinfection of natural alkaline surface water (pH 8.6 ± 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2(-), NO3(-), NH4(+), HPO4(2-), and bicarbonate (HCO3(-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.

Inactivation of Uropathogenic Escherichia coli in Ground Chicken Meat Using High Pressure Processing and Gamma Radiation, and in Purge and Chicken Meat Surfaces by Ultraviolet Light

PubMed Central

Sommers, Christopher H.; Scullen, O. J.; Sheen, Shiowshuh

2016-01-01

Extraintestinal pathogenic Escherichia coli, including uropathogenic E. coli (UPEC), are common contaminants in poultry meat and may cause urinary tract infections after colonization of the gastrointestinal tract and transfer of contaminated feces to the urethra. Three non-thermal processing technologies used to improve the safety and shelf-life of both human and pet foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). Multi-isolate cocktails of UPEC were inoculated into ground chicken which was then treated with HPP (4°C, 0–25 min) at 300, 400, or 500 MPa. HPP D10, the processing conditions needed to inactivate 1 log of UPEC, was 30.6, 8.37, and 4.43 min at 300, 400, and 500 MPa, respectively. When the UPEC was inoculated into ground chicken and gamma irradiated (4 and -20°C) the GR D10 were 0.28 and 0.36 kGy, respectively. The UV-C D10 of UPEC in chicken suspended in exudate and placed on stainless steel and plastic food contact surfaces ranged from 11.4 to 12.9 mJ/cm2. UV-C inactivated ca. 0.6 log of UPEC on chicken breast meat. These results indicate that existing non-thermal processing technologies such as HPP, GR, and UV-C can significantly reduce UPEC levels in poultry meat or exudate and provide safer poultry products for at-risk consumers. PMID:27148167

Identifying and Inactivating Bacterial Spores

NASA Technical Reports Server (NTRS)

Newcombe, David; Dekas, Anne; Venkateswaran, Kasthuri

2009-01-01

Problems associated with, and new strategies for, inactivating resistant organisms like Bacillus canaveralius (found at Kennedy Space Center during a survey of three NASA cleanrooms) have been defined. Identifying the particular component of the spore that allows its heightened resistance can guide the development of sterilization procedures that are targeted to the specific molecules responsible for resistance, while avoiding using unduly harsh methods that jeopardize equipment. The key element of spore resistance is a multilayered protein shell that encases the spore called the spore coat. The coat of the best-studied spore-forming microbe, B. subtilis, consists of at least 45 proteins, most of which are poorly characterized. Several protective roles for the coat are well characterized including resistance to desiccation, large toxic molecules, ortho-phthalaldehyde, and ultraviolet (UV) radiation. One important long-term specific goal is an improved sterilization procedure that will enable NASA to meet planetary protection requirements without a terminal heat sterilization step. This would support the implementation of planetary protection policies for life-detection missions. Typically, hospitals and government agencies use biological indicators to ensure the quality control of sterilization processes. The spores of B. canaveralius that are more resistant to osmotic stress would serve as a better biological indicator for potential survival than those in use currently.

The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models

NASA Astrophysics Data System (ADS)

Mayotte, Jean-Marc; Grabs, Thomas; Sutliff-Johansson, Stacy; Bishop, Kevin

2017-06-01

This study examined how the inactivation of bacteriophage MS2 in water was affected by ionic strength (IS) and dissolved organic carbon (DOC) using static batch inactivation experiments at 4 °C conducted over a period of 2 months. Experimental conditions were characteristic of an operational managed aquifer recharge (MAR) scheme in Uppsala, Sweden. Experimental data were fit with constant and time-dependent inactivation models using two methods: (1) traditional linear and nonlinear least-squares techniques; and (2) a Monte-Carlo based parameter estimation technique called generalized likelihood uncertainty estimation (GLUE). The least-squares and GLUE methodologies gave very similar estimates of the model parameters and their uncertainty. This demonstrates that GLUE can be used as a viable alternative to traditional least-squares parameter estimation techniques for fitting of virus inactivation models. Results showed a slight increase in constant inactivation rates following an increase in the DOC concentrations, suggesting that the presence of organic carbon enhanced the inactivation of MS2. The experiment with a high IS and a low DOC was the only experiment which showed that MS2 inactivation may have been time-dependent. However, results from the GLUE methodology indicated that models of constant inactivation were able to describe all of the experiments. This suggested that inactivation time-series longer than 2 months were needed in order to provide concrete conclusions regarding the time-dependency of MS2 inactivation at 4 °C under these experimental conditions.

Method for determining virus inactivation during sludge treatment processes.

PubMed Central

Traub, F; Spillmann, S K; Wyler, R

1986-01-01

A simple and reliable method is described which allows determination of virus inactivation rates during sludge treatment processes in situ. Bacteriophage f2 was adsorbed onto an electropositive membrane filter which was then sandwiched between two polycarbonate membranes with pores smaller than the virus diameter. The resulting sandwich was fixed in an open filter holder, and several such devices were connected before being exposed in sludge-digesting tanks. The device described prevented uncontrolled virus escape, but allowed direct contact of the various inactivating or stabilizing substances present in the environment tested with the virus adsorbed to the carrier membrane. After exposure to an environment, the surviving fraction of virus was eluted from the inner filter and determined by plaque counting. By using polycarbonate membranes without pores for sandwiching, the influence of temperature alone on virus inactivation could be measured. Thermophilic fermentation at 60 degrees C and at 65 kPa pressure led to a bacteriophage f2 titer reduction of 3.5 log10 units per h, whereas during thermophilic digestion at 54.5 degrees C titers decreased 1.2 log10 units per h. During mesophilic digestion an inactivation rate of only 0.04 log10 units per h was observed. Under these latter conditions, temperature had only a minor effect (19%) on virus inactivation, whereas at 54.5 degrees C during thermophilic digestion heat accounted for 32% of the total inactivation, and during thermophilic fermentation at 60 degrees C temperature and pressure were 100% responsible for virus denaturation. PMID:3532955

MPLEx: a method for simultaneous pathogen inactivation and extraction of samples for multi-omics profiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnum-Johnson, Kristin E.; Kyle, Jennifer E.; Eisfeld, Amie J.

The continued emergence and spread of infectious agents is of increasing concern due to increased population growth and the associated increased livestock production to meet food demands, increased urbanization and land-use changes, and greater travel. A systems biology approach to infectious disease research can significantly advance our understanding of host-pathogen relationships and facilitate the development of new therapies and vaccines. Molecular characterization of infectious samples outside of appropriate biosafety containment can only take place subsequent to pathogen inactivation. Herein, we describe a modified Folch extraction using chloroform/methanol that facilitates the molecular characterization of infectious samples by enabling simultaneous pathogen inactivationmore » and extraction of proteins, metabolites, and lipids for subsequent mass spectrometry-based multi-omics measurements. This metabolite, protein and lipid extraction (MPLEx) method resulted in complete inactivation of bacterial and viral pathogens with exposed lipid membranes, including Yersinia pestis, Salmonella Typhimurium, and Campylobacter jejuni in pure culture, and Yersinia pestis, Campylobacter jejuni, West Nile, MERS-CoV, Ebola, and influenza H7N9 viruses in infection studies. Partial inactivation was observed for pathogens without exposed lipid membranes including 99.99% inactivation of community-associated methicillin-resistant Staphylococcus aureus, 99.6% and >99% inactivation of Clostridium difficile spores and vegetative cells, respectively, and 50% inactivation of adenovirus type 5. To demonstrate that MPLEx yields biomaterial of sufficient quality for subsequent multi-omics analyses, we highlight select proteomics, metabolomics and lipidomics data from human epithelial lung cells infected with wild-type and mutant forms of influenza H7N9. We believe that MPLEx will facilitate systems biology studies of infectious samples by enabling simultaneous pathogen inactivation and multi-omics measurements from a single specimen.« less

The Use of Gamma Radiation for the Preparation of Virus Vaccines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polley, John R.

1962-08-01

Suspensions of the viruses (mumps, influenza A (PR8), A/sub 1/ (FM/sub 1/ ), B, and swine influenza A) were irradiated in a Co/sup 60/ cell with a dose of 1.5 x 10/sup 6/ rad, which is about 50% higher thin the dose calculated to be required for inactivation. A protective agent such as histidine or Na p- aminohippurite was added to purified suspensions of influenzi and mumps viruses. It was then possible to inactivate them while retaining most of the hemagglutination titer. It was demonstrated in mice that a vaccine prepared from a mouse-adapted virus (Shope's swine influenza) conferred protectionmore » against challenge by the live virus and produced an antibody response as measured by the hemagglutinationinhibition technique. Vaccines prepared with the viruses of influenza A(PR8), influenza B, and mumps were shown to produce antibody responses in guinea pigs as measured by the hemigglutination-inhibition and serum neutralization techniques. The use of gamma irradiation has an advantage over most chemical procedures because its dosage of inactivation can be more accurately controlled. (H.H.D.)« less

Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

NASA Astrophysics Data System (ADS)

Paulino-Lima, Ivan Gláucio; Pilling, Sérgio; Janot-Pacheco, Eduardo; de Brito, Arnaldo Naves; Barbosa, João Alexandre Ribeiro Gonçalves; Leitão, Alvaro Costa; Lage, Claudia de Alencar Santos

2010-08-01

The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m -2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.

Operation Sun Beam, Shots Little Feller I, II and Johnie Boy. Project officers report. Project 6. 6. Electromagnetic measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, W.D.; Livingston, P.M.; Rutter, R.L.

Of considerable interest from both a physical and practical viewpoint is the coupling of electromagnetic energy from a nuclear explosion into various electrical systems in the vicinity of the burst. A series of electromagnetic measurements were made on Shots Little Feller I, Little Feller II, and Johnie Boy. It is clear from the records that radiation shielding must be given closer consideration in future tests. Due to equipment failure and radiation inactivation, only the Johnie Boy dynamic current measurement and the passive peak current indicators on all three events are interpretable.

Problems in mechanistic theoretical models for cell transformation by ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, A.; Holley, W.R.

1991-10-01

A mechanistic model based on yields of double strand breaks has been developed to determine the dose response curves for cell transformation frequencies. At its present stage the model is applicable to immortal cell lines and to various qualities (X-rays, Neon and Iron) of ionizing radiation. Presently, we have considered four types of processes which can lead to activation phenomena: (1) point mutation events on a regulatory segment of selected oncogenes, (2) inactivation of suppressor genes, through point mutation, (3) deletion of a suppressor gene by a single track, and (4) deletion of a suppressor gene by two tracks.

Hybrid soliwave technique for mitigating sulfate-reducing bacteria in controlling biocorrosion: a case study on crude oil sample.

PubMed

Mohd Ali, Muhammad Khairool Fahmy Bin; Abu Bakar, Akrima; Md Noor, Norhazilan; Yahaya, Nordin; Ismail, Mardhiah; Rashid, Ahmad Safuan

2017-10-01

Microbiologically influenced corrosion (MIC) is among the common corrosion types for buried and deep-water pipelines that result in costly repair and pipeline failure. Sulfate-reducing bacteria (SRB) are commonly known as the culprit of MIC. The aim of this work is to investigate the performance of combination of ultrasound (US) irradiation and ultraviolet (UV) radiation (known as Hybrid soliwave technique, HyST) at pilot scale to inactivate SRB. The influence of different reaction times with respect to US irradiation and UV radiation and synergistic effect toward SRB consortium was tested and discussed. In this research, the effect of HyST treatment toward SRB extermination and corrosion studies of carbon steel coupon upon SRB activity before and after the treatment were performed using weight loss method. The carbon steel coupons immersed in SRB sample were exposed to HyST treatment at different time of exposure. Additionally, Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy were used to investigate the corrosion morphology in verifying the end product of SRB activity and corrosion formation after treatment. Results have shown that the US irradiation treatment gives a synergistic effect when combined with UV radiation in mitigating the SRB consortium.

Differential toxicity of drinking water disinfected with combinations of ultraviolet radiation and chlorine.

PubMed

Plewa, Michael J; Wagner, Elizabeth D; Metz, Deborah H; Kashinkunti, Ramesh; Jamriska, Katherine J; Meyer, Maria

2012-07-17

Alternative technologies to disinfect drinking water such as ultraviolet (UV) disinfection are becoming more widespread. The benefits of UV disinfection include reduced risk of microbial pathogens such as Cryptosporidium and reduced production of regulated drinking water disinfection byproducts (DBPs). The objective of this research was to determine if mammalian cell cytotoxicity and genotoxicity varied in response to different chlorination protocols with and without polychromatic medium pressure UV (MPUV) and monochromatic low pressure UV (LPUV) disinfection technologies. The specific aims were to analyze the mammalian cell cytotoxicity and genotoxicity of concentrated organic fractions from source water before and after chlorination and to determine the cytotoxicity and genotoxicity of the concentrated organic fractions from water samples treated with UV alone or UV before or after chlorination. Exposure of granular activated carbon-filtered Ohio River water to UV alone resulted in the lowest levels of mammalian cell cytotoxicity and genotoxicity. With combinations of UV and chlorine, the lowest levels of cytotoxicity and genotoxicity were observed with MPUV radiation. The best combined UV plus chlorine methodology that generated the lowest cytotoxicity and genotoxicity employed chlorination first followed by MPUV radiation. These data may prove important in the development of multibarrier methods of pathogen inactivation of drinking water, while limiting unintended toxic consequences.

Solar disinfection of drinking water contained in transparent plastic bottles: characterizing the bacterial inactivation process.

PubMed

McGuigan, K G; Joyce, T M; Conroy, R M; Gillespie, J B; Elmore-Meegan, M

1998-06-01

A series of experiments is reported to identify and characterize the inactivation process in operation when drinking water, heavily contaminated with a Kenyan isolate of Escherichia coli, is stored in transparent plastic bottles that are then exposed to sunlight. The roles of optical and thermal inactivation mechanisms are studied in detail by simulating conditions of optical irradiance, water turbidity and temperature, which were recorded during a series of solar disinfection measurements carried out in the Kenyan Rift Valley. Optical inactivation effects are observed even in highly turbid water (200 ntu) and at low irradiances of only 10 mW cm-2. Thermal inactivation is found to be important only at water temperatures above 45 degrees C, at which point strong synergy between optical and thermal inactivation processes is observed. The results confirm that, where strong sunshine is available, solar disinfection of drinking water is an effective, low cost method for improving water quality and may be of particular use to refugee camps in disaster areas. Strategies for improving bacterial inactivation are discussed.

Targeting Extracellular Histones with Novel RNA Biodrugs for the Treatment of Acute Lung Injury

DTIC Science & Technology

2017-10-01

inactivate) circulating histones and prevent the morbidity and mortality associated with multiple organ dysfunction/ acute respiratory distress syndrome ...patients. 15. SUBJECT TERMS Acute lung injury (ALI), acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome , extracellular...are acute lung injury (ALI) from smoke/chlorine gas inhalation, burns, radiation , influenza and severe infection. Only recently have investigators

Inactivation of Toxoplasma gondii on blueberries using low dose irradiation without affecting quality

USDA-ARS?s Scientific Manuscript database

Blueberries (10 g) inoculated with T. gondii (5 log oocysts/g) were exposed to an absorbed dose of 0 (control), 0.2, 0.4 or 0.6 kGy gamma radiation at 4°C. After treatment, oocysts were recovered from berries by washing, and excysted sporozoites were enumerated using a plaque assay. Vero cells wer...

Impact of environmental factors on efficacy of upper-room air ultraviolet germicidal irradiation for inactivating airborne mycobacteria.

PubMed

Xu, Peng; Kujundzic, Elmira; Peccia, Jordan; Schafer, Millie P; Moss, Gene; Hernandez, Mark; Miller, Shelly L

2005-12-15

This study evaluated the efficacy of an upper-room air ultraviolet germicidal irradiation (UVGI) system for inactivating airborne bacteria, which irradiates the upper part of a room while minimizing radiation exposure to persons in the lower part of the room. A full-scale test room (87 m3), fitted with a UVGI system consisting of 9 louvered wall and ceiling fixtures (504 W all lamps operating) was operated at 24 and 34 degrees C, between 25 and 90% relative humidity, and at three ventilation rates. Mycobacterium parafortuitum cells were aerosolized into the room such that their numbers and physiologic state were comparable both with and without the UVGI system operating. Airborne bacteria were collected in duplicate using liquid impingers and quantified with direct epifluorescent microscopy and standard culturing assay. Performance of the UVGI system degraded significantly when the relative humidity was increased from 50% to 75-90% RH, the horizontal UV fluence rate distribution was skewed to one side compared to being evenly dispersed, and the room air temperature was stratified from hot at the ceiling to cold at the floor. The inactivation rate increased linearly with effective UV fluence rate up to 5 microW cm(-2); an increase in the fluence rate above this level did not yield a proportional increase in inactivation rate.

Inactivation of Aspergillus flavus in drinking water after treatment with UV irradiation followed by chlorination.

PubMed

Al-Gabr, Hamid Mohammad; Zheng, Tianling; Yu, Xin

2013-10-01

The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log10 control of A. flavus was achieved after 30 s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 s UV irradiation followed by chlorination produced 4 log10 reduction of A. flavus at chlorine concentrations of 2 and 3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations. Copyright © 2013 Elsevier B.V. All rights reserved.

In Vitro Cytotoxicity of Low-Dose-Rate Radioimmunotherapy by the Alpha-Emitting Radioimmunoconjugate Thorium-227-DOTA-Rituximab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahle, Jostein, E-mail: jostein.dahle@rr-research.n; Krogh, Cecilie; Melhus, Katrine B.

2009-11-01

Purpose: To determine whether the low-dose-rate alpha-particle-emitting radioimmunoconjugate {sup 227}Th-1,4,7,10-p-isothiocyanato-benzyl-tetraazacyclododecane-1,4,7, 10-tetraacetic acid (DOTA)-rituximab can be used to inactivate lymphoma cells growing as single cells and small colonies. Methods and Materials: CD20-positive lymphoma cell lines were treated with {sup 227}Th-DOTA-rituximab for 1-5 weeks. To simulate the in vivo situation with continuous but decreasing supply of radioimmunoconjugates from the blood pool, the cells were not washed after incubation with {sup 227}Th-DOTA-rituximab, but half of the medium was replaced with fresh medium, and cell concentration and cell-bound activity were determined every other day after start of incubation. A microdosimetric model was established tomore » estimate the average number of hits in the nucleus for different localizations of activity. Results: There was a specific targeted effect on cell growth of the {sup 227}Th-DOTA-rituximab treatment. Although the cells were not washed after incubation with {sup 227}Th-DOTA-rituximab, the average contribution of activity in the medium to the mean dose was only 6%, whereas the average contribution from activity on the cells' own surface was 78%. The mean dose rates after incubation with 800 Bq/mL {sup 227}Th-DOTA-rituximab varied from 0.01 to 0.03 cGy/min. The average delay in growing from 10{sup 5} to 10{sup 7} cells/mL was 15 days when the cells were treated with a mean absorbed radiation dose of 2 Gy alpha-particle radiation from {sup 227}Th-DOTA-rituximab, whereas it was 11 days when the cells were irradiated with 6 Gy of X-radiation. The relative biologic effect of the treatment was estimated to be 2.9-3.4. Conclusions: The low-dose-rate radioimmunoconjugate {sup 227}Th-DOTA-rituximab is suitable for inactivation of single lymphoma cells and small colonies of lymphoma cells.« less

Positron emitter labeled enzyme inhibitors

DOEpatents

Fowler, Joanna S.; MacGregor, Robert R.; Wolf, Alfred P.; Langstrom, Bengt

1990-01-01

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream.

PubMed

Rizzo, L; Fiorentino, A; Anselmo, A

2012-06-15

The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC>256 μg/mL) and SMZ (MIC>1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t(1/2)=24 min)

Functionalization of multiwalled carbon nanotubes by microwave irradiation for lysozyme attachment: comparison of covalent and adsorption methods by kinetics of thermal inactivation

NASA Astrophysics Data System (ADS)

Puentes-Camacho, Daniel; Velázquez, Enrique F.; Rodríguez-Félix, Dora E.; Castillo-Ortega, Mónica; Sotelo-Mundo, Rogerio R.; del Castillo-Castro, Teresa

2017-12-01

Proteins suffer changes in their tertiary structure when they are immobilized, and enzymatic activity is affected due to the low biocompatibility of some supporting materials. In this work immobilization of lysozyme on carbon nanotubes previously functionalized by microwave irradiation was studied. The effectiveness of the microwave-assisted acid treatment of carbon nanotubes was evaluated by XPS, TEM, Raman and FTIR spectroscopy. The carboxylic modification of nanotube surfaces by this fast, simple and feasible method allowed the physical adsorption and covalent linking of active lysozyme onto the carbonaceous material. Thermal inactivation kinetics, thermodynamic parameters and storage stability were studied for adsorbed and covalent enzyme complexes. A major stability was found for lysozyme immobilized by the covalent method, the activation energy for inactivation of the enzyme was higher for the covalent method and it was stable after 50 d of storage at 4 °C. The current study highlights the effect of protein immobilization method on the biotechnological potential of nanostructured biocatalysts.

Efficacy of ultraviolet radiation as an alternative technology to inactivate microorganisms in grape juices and wines.

PubMed

Fredericks, Ilse N; du Toit, Maret; Krügel, Maricel

2011-05-01

Since sulphur dioxide (SO(2)) is associated with health risks, the wine industry endeavours to reduce SO(2) levels in wines with new innovative techniques. The aim of this study was, therefore, to investigate the efficacy of ultraviolet radiation (UV)-C (254 nm) as an alternative technology to inactivate microorganisms in grape juices and wines. A pilot-scale UV-C technology (SurePure, South Africa) consisting of an UV-C germicidal lamp (100 W output; 30 W UV-C output) was used to apply UV-C dosages ranging from 0 to 3672 J l(-1), at a constant flow rate of 4000 l h(-1) (Re > 7500). Yeasts, lactic and acetic acid bacteria were singly and co-inoculated into 20 l batches of Chenin blanc juice, Shiraz juice, Chardonnay wine and Pinotage wine, respectively. A dosage of 3672 J l(-1), resulted in an average log(10) microbial reduction of 4.97 and 4.89 in Chardonnay and Pinotage, respectively. In Chenin blanc and Shiraz juice, an average log(10) reduction of 4.48 and 4.25 was obtained, respectively. UV-C efficacy may be influenced by liquid properties such as colour and turbidity. These results had clearly indicated significant (p < 0.05) germicidal effect against wine-specific microorganisms; hence, UV-C radiation may stabilize grape juice and wine microbiologically in conjunction with reduced SO(2) levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Mutagenic and lethal effects of (5-/sup 125/I)lodo-2'-deoxyuridine incorporated into DNA of mammalian cells, and their RBEs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyazaki, N.; Fujiwara, Y.

1981-12-01

Decay of /sup 125/I unifilarly incorporated as 5-iodo-2'-deoxyuridine (IdUrd) into DNA of V79 Chinese hamster cells was approximately an order of magnitude more effective in inducing both 6-thioguanine-resistant mutation and cell inactivation than external X rays under equivalent conditions. RBEs of mutation and killing induced by /sup 125/I decays, compared with 170-kVp X rays of low LET, were approx. = 11 for mutation (ratio of the induction rate in frequency/rad = 11.3 X 10/sup -7/ (/sup 125/I)/100 X 10/sup -7/ (X rays at -79/sup o/C)) and approx. = 10 for cell inactivation (D/sub 0/ ratio = 505 rad (X raysmore » at -79/sup o/C)/52 rad (/sup 125/I)). These RBE values may well exceed the reported maximum values for high-LET radiation in the LET range of 80-110 keV/..mu..m, suggesting that the Auger effect is different from the high-LET radiation effect alone. Thus these biological consequences arise not only from radiation effects of Auger electrons on the immediate vicinity in DNA, but also from the nonionogenic effect through charge transfer processes. In addition, higher inductions of mutation and killing by external X rays in unifilarly IdUrd-substituted cells than in ordinal cells were observed, suggesting a possible involvement of X-ray-induced Auger phenomenon in iodine in DNA.« less

Pulsed UV laser light on Escherichia coli and Saccharomyces cerevisiae suspended in non-alcoholic beer

PubMed Central

Hosseini, SM; Azar-Daryany, MK; Massudi, R; Elikaei, A

2011-01-01

Background The aim of this study was to investigate the effect of pulsed ultra-violet (UV) irradiation on inactivation of beer spoilage microorganisms. UV irradiation is nowadays cost effective enough to compete with traditional biological, physical, and chemical treatment technologies and has become an alternative to such methods. Material and Methods Photoinactivation effects of pulsed UV laser with the wavelengths of 355 and 266 nm, which inactivate typical prokaryotic (Escherichia coli) and eukaryotic (Saccharomyces cerevisiae) microorganisms, were examined with different doses and exposure times. Results A dose of 100 J/cm2 of the 355 nm pulsed UV laser was able to reduce about 1 to 2 log (88.75%) of E.coli with the population of 1.6×108 colony-forming units (CFU/ml), and 97% of 3.2×107, 3×106, 5.5×105, and 9×104 CFU/ml. In the case of 266 nm, more than 99% reduction in E. coli serial dilutions was inactivated, using 10 J/cm2 with exception of 7×104 CFU/ml which was not detected any bacterial growth using 5 J/cm2. In addition, 50, 40, and 20 J/cm2 energy were used successfully to inactivate S. cerevisiae at the populations of 5.4×106, 7×105, 5×104 and 4×103 CFU/ml, respectively. As a result, pulsed UV Laser with 266 nm was strong enough to inactivate a high titer of bacterial and yeast indicator standards suspended in non-alcoholic beer in comparison with 355nm doses. Conclusion Results indicate that pulsed UV technology, in principle, is an attractive alternative to conventional methods for the inactivation of indicator microorganisms and has potential in irradiation of unpasteurized beer. PMID:22347580

Plasma Decontamination: A Case Study on Kill Efficacy of Geobacillus stearothermophilus Spores on Different Carrier Materials.

PubMed

Semmler, Egmont; Novak, Wenzel; Allinson, Wilf; Wallis, Darren; Wood, Nigel; Awakowicz, Peter; Wunderlich, Joachim

2016-01-01

A new technology to the pharmaceutical field is presented: surface decontamination by plasmas The technology is comparable to established barrier systems like e-beam, volatile hydrogen peroxide, or radiation inactivation of microbiological contaminations. This plasma technology is part of a fully automated and validated syringe filling line at a major pharmaceutical company and is in production operation. Incoming pre-sterilized syringe containers ("tubs") are processed by plasma, solely on the outside, and passed into the aseptic filling isolator upon successful decontamination. The objective of this article is to present the operating principles and develop and establish a validation routine on the basis of standard commercial biological indicators. Their decontamination efficacies are determined and correlated to the actual inactivation efficacy on the pharmaceutical packaging material.The reference setup is explained in detail and a short presentation of the cycle development and the relevant plasma control parameters is given, with a special focus on the in-process monitor determining the cycle validity. Different microbial inactivation mechanisms are also discussed and evaluated for their contribution and interaction to enhance plasma decontamination. A material-dependent inactivation behavior was observed. In order to be able to correlate the tub surface inactivation of Geobacillus stearothermophilus endospores to metallic biological indicators, a comparative study was performed. Through consistently demonstrating the linear inactivation behavior between the different materials, it becomes possible to develop an effective and time-saving validation scheme. The challenge in new decontamination systems lies in a thorough validation of the inactivation efficacy under different operating regimes. With plasma, as an ionized gas, a new barrier concept is introduced into pharmaceutical aseptic processing of syringes. The presented system operates in vacuum and only decontaminates the outer surface of pre-sterilized syringe containers ("tubs"), before they are transferred into the aseptic area. The plasma does not penetrate into the tub. This article discusses the phase from development and test germ selection, across the identified sporicidal mechanisms, to a proposal for a validation scheme on the basis of commercially available biological indicators. A special focus is placed on an extensive investigation to establish a link between the tub surface microbial kill (polystyrene and Tyvek(and (2)) ) and biological indicator inactivation (stainless steel). Additionally, a rationale is developed on how an optical in-process monitor can be applied to establish a validatable limit on the base of the predetermined inactivation data of Geobacillus stearothermophilus endospores. © PDA, Inc. 2016.

Kinetics model for initiation and promotion for describing tumor prevalence from HZE radiation

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Wilson, John W.

1994-01-01

A kinetics model for cellular repair and misrepair for multiple radiation-induced lesions (mutation-inactivation) is coupled to a two-mutation model of initiation and promotion in tissue to provide a parametric description of tumor prevalence in the Harderian gland in a mouse. Dose-response curves are described for gamma-rays and relativistic ions. The effects of nuclear fragmentation are also considered for high-energy proton and alpha particle exposures The model described provides a parametric description of age-dependent cancer induction for a wide range of radiation fields. We also consider the two hypotheses that radiation acts either solely as an initiator or as both initiator and promoter and make model calculations for fractionation exposures from gamma-rays and relativistic Fe ions. For fractionated Fe exposures, an inverse dose-rate effect is provided by a promotion hypothesis using a mutation rate for promotion typical of single-gene mutations.

Radiation biology of HZE particles

NASA Technical Reports Server (NTRS)

Nelson, Gregory A.

1990-01-01

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long duration space flights where exposure levels represent a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets which may be related to charge, velocity, or rate of energy loss. There are many consequences of this feature to biological endpoints when compared to effects of ionizing photons. Dose vs response and dose rate kinetics are modified, DNA and cellular repair systems are altered in their abilities to cope with damage and, the qualitative features of damage are unique for different ions. These features must be incorporated into any risk assessment system for radiation health management. HZE induced mutation, cell inactivation and altered organogenesis will be discussed emphasizing studies with the nematode Caenorhabditis elegans and cultured cells. Observations from radiobiology experiments in space will also be reviewed along with plans for future space-based studies.

Radiobiological studies with the nematode Caenorhabditis elegans. Genetic and developmental effects of high LET radiation

NASA Technical Reports Server (NTRS)

Nelson, G. A.; Schubert, W. W.; Marshall, T. M.

1992-01-01

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long-duration space flights where exposure levels represent a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets. There are many consequences of this feature to biological endpoints when compared with effects of ionizing photons. Dose vs response and dose-rate kinetics may be modified, DNA and cellular repair systems may be altered in their abilities to cope with damage, and the qualitative features of damage may be unique for different ions. The nematode Caenorhabditis elegans is being used to address these and related questions associated with exposure to radiation. HZE-induced mutation, chromosome aberration, cell inactivation and altered organogenesis are discussed along with plans for radiobiological experiments in space.

Treatment alternatives of slaughterhouse wastes, and their effect on the inactivation of different pathogens: a review.

PubMed

Franke-Whittle, Ingrid H; Insam, Heribert

2013-05-01

Slaughterhouse wastes are a potential reservoir of bacterial, viral, prion and parasitic pathogens, capable of infecting both animals and humans. A quick, cost effective and safe disposal method is thus essential in order to reduce the risk of disease following animal slaughter. Different methods for the disposal of such wastes exist, including composting, anaerobic digestion (AD), alkaline hydrolysis (AH), rendering, incineration and burning. Composting is a disposal method that allows a recycling of the slaughterhouse waste nutrients back into the earth. The high fat and protein content of slaughterhouse wastes mean however, that such wastes are an excellent substrate for AD processes, resulting in both the disposal of wastes, a recycling of nutrients (soil amendment with sludge), and in methane production. Concerns exist as to whether AD and composting processes can inactivate pathogens. In contrast, AH is capable of the inactivation of almost all known microorganisms. This review was conducted in order to compare three different methods of slaughterhouse waste disposal, as regards to their ability to inactivate various microbial pathogens. The intention was to investigate whether AD could be used for waste disposal (either alone, or in combination with another process) such that both energy can be obtained and potentially hazardous materials be disposed of.

Treatment alternatives of slaughterhouse wastes, and their effect on the inactivation of different pathogens: A review

PubMed Central

2013-01-01

Slaughterhouse wastes are a potential reservoir of bacterial, viral, prion and parasitic pathogens, capable of infecting both animals and humans. A quick, cost effective and safe disposal method is thus essential in order to reduce the risk of disease following animal slaughter. Different methods for the disposal of such wastes exist, including composting, anaerobic digestion (AD), alkaline hydrolysis (AH), rendering, incineration and burning. Composting is a disposal method that allows a recycling of the slaughterhouse waste nutrients back into the earth. The high fat and protein content of slaughterhouse wastes mean however, that such wastes are an excellent substrate for AD processes, resulting in both the disposal of wastes, a recycling of nutrients (soil amendment with sludge), and in methane production. Concerns exist as to whether AD and composting processes can inactivate pathogens. In contrast, AH is capable of the inactivation of almost all known microorganisms. This review was conducted in order to compare three different methods of slaughterhouse waste disposal, as regards to their ability to inactivate various microbial pathogens. The intention was to investigate whether AD could be used for waste disposal (either alone, or in combination with another process) such that both energy can be obtained and potentially hazardous materials be disposed of. PMID:22694189

Inactivation of natural enteric bacteria in real municipal wastewater by solar photo-Fenton at neutral pH.

PubMed

Ortega-Gómez, E; Esteban García, B; Ballesteros Martín, M M; Fernández Ibáñez, P; Sánchez Pérez, J A

2014-10-15

This study analyses the use of the solar photo-Fenton treatment in compound parabolic collector photo-reactors at neutral pH for the inactivation of wild enteric Escherichia coli and total coliform present in secondary effluents of a municipal wastewater treatment plant (SEWWTP). Control experiments were carried out to find out the individual effects of mechanical stress, pH, reactants concentration, and UVA radiation as well as the combined effects of UVA-Fe and UVA-H2O2. The synergistic germicidal effect of solar-UVA with 50 mg L(-1) of H2O2 led to complete disinfection (up to the detection limit) of total coliforms within 120 min. The disinfection process was accelerated by photo-Fenton, achieving total inactivation in 60 min reducing natural bicarbonate concentration found in the SEWWTP from 250 to 100 mg L(-1) did not give rise to a significant enhancement in bacterial inactivation. Additionally, the effect of hydrogen peroxide and iron dosage was evaluated. The best conditions were 50 mg L(-1) of H2O2 and 20 mg L(-1) of Fe(2+). Due to the variability of the SEWWTP during autumn and winter seasons, the inactivation kinetic constant varied between 0.07 ± 0.04 and 0.17 ± 0.04 min(-1). Moreover, the water treated by solar photo-Fenton fulfilled the microbiological quality requirement for wastewater reuse in irrigation as per the WHO guidelines and in particular for Spanish legislation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of various conditions on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in fresh-cut lettuce using ultraviolet radiation.

PubMed

Kim, Yoon-Hee; Jeong, Seul-Gi; Back, Kyeong-Hwan; Park, Ki-Hwan; Chung, Myung-Sub; Kang, Dong-Hyun

2013-09-16

The effect of various conditions on inactivation of foodborne pathogens and quality of fresh-cut lettuce during ultraviolet (254 nm, UVC) radiation was investigated. Lettuce was inoculated with a cocktail of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated at different temperatures (4 and 25 °C), distances between sample and lamp (10 and 50 cm), type of exposure (illuminated from one or two sides), UV intensities (1.36 to 6.80 mW/cm²), and exposure times (0.5 to 10 min), sequentially. UV treatment at 25 °C for 1 min achieved 1.45-, 1.35-, and 2.12-log reductions in surface-inoculated E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, whereas the reduction of these pathogens at 4 °C was 0.31, 0.57, and 1.16 log, respectively. UV radiation was most effective when distance from UV lamp to the sample was minimal (10 cm) and radiation area was maximal (two-sided exposure). All UV intensities significantly (P<0.05) reduced the three pathogens after 10 min exposure, but the effect of treatment was correlated with UV intensity and exposure time. Color values and texture parameters of lettuce subjected to UV treatment under the optimum conditions (25 °C, 10 cm between sample and lamp, two-sided exposure, 6.80 mW/cm²) were not significantly (P>0.05) different from those of nontreated samples up to 5 min exposure. However, these qualities significantly (P<0.05) changed at prolonged treatment time. These results suggest that UV radiation under optimized conditions could reduce foodborne pathogens without adversely affecting color quality properties of fresh-cut lettuce. © 2013 Elsevier B.V. All rights reserved.

A New View of Radiation-Induced Cancer: Integrating Short-and Long-Term Processes. Part I: Approach

NASA Technical Reports Server (NTRS)

Shuryak, Igor; Hahnfeldt, Philip; Hlatky, Lynn; Sachs, Rainer K.; Brenner, David J.

2009-01-01

Mathematical models of radiation carcinogenesis are important for understanding mechanisms and for interpreting or extrapolating risk. There are two classes of such models: (1) long-term formalisms that track premalignant cell numbers throughout an entire lifetime but treat initial radiation dose-response simplistically and (2) short-term formalisms that provide a detailed initial dose-response even for complicated radiation protocols, but address its modulation during the subsequent cancer latency period only indirectly. We argue that integrating short- and long-term models is needed. As an example of this novel approach, we integrate a stochastic short-term initiation/ inactivation/repopulation model with a deterministic two-stage long-term model. Within this new formalism, the following assumptions are implemented: radiation initiates, promotes, or kills pre-malignant cells; a pre-malignant cell generates a clone, which, if it survives, quickly reaches a size limitation; the clone subsequently grows more slowly and can eventually generate a malignant cell; the carcinogenic potential of pre-malignant cells decreases with age.

Survival of antibiotic resistant bacteria following artificial solar radiation of secondary wastewater effluent.

PubMed

Glady-Croue, Julie; Niu, Xi-Zhi; Ramsay, Joshua P; Watkin, Elizabeth; Murphy, Riley J T; Croue, Jean-Philippe

2018-06-01

Urban wastewater treatment plant effluents represent one of the major emission sources of antibiotic-resistant bacteria (ARB) in natural aquatic environments. In this study, the effect of artificial solar radiation on total culturable heterotrophic bacteria and ARB (including amoxicillin-resistant, ciprofloxacin-resistant, rifampicin-resistant, sulfamethoxazole-resistant, and tetracycline-resistant bacteria) present in secondary effluent was investigated. Artificial solar radiation was effective in inactivating the majority of environmental bacteria, however, the proportion of strains with ciprofloxacin-resistance and rifampicin-resistance increased in the surviving populations. Isolates of Pseudomonas putida, Serratia marcescens, and Stenotrophomonas maltophilia nosocomial pathogens were identified as resistant to solar radiation and to at least three antibiotics. Draft genome sequencing and typing revealed isolates carrying multiple resistance genes; where S. maltophilia (resistant to all studied antibiotics) sequence type was similar to strains isolated in blood infections. Results from this study confirm that solar radiation reduces total bacterial load in secondary effluent, but may indirectly increase the relative abundance of ARB. Copyright © 2018 Elsevier B.V. All rights reserved.

THE EFFECTS OF ULTRAVIOLET LIGHT AND GAMMA RAYS ON CELL LIPIDS AND THE PHYSIOLOGICAL ACTION OF IRRADIATED LIPIDS. Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernheim, F.; Wilbur, K.M.

1962-03-26

Results are summarized from a series of studies on the effects of ultraviolet and ionizing radiation on the oxidation of cell lipids. It was shown that both in vitro and in vivo radiation produced oxidation products of lipids that inhibited the activity of certain oxidative enzymes, depolymerized desoxyribonucleoprotein, inhibited the division of marine eggs, and retarded bacterial growth. The presence of antioxidant activity was also demonstrated in tissues. The significant feature of antioxidant compounds with respect to the biological effects of radiation was shown to be the inhibition of the oxidation of lipids. In irradiated animals the antioxidant activity ofmore » the intestinal mucosa and the activity of phospholipase decreased. Experiments showed that radiation had not destroyed the enzyme but had inactivated the activator. Results are also summarized from a study on the effects of ionizing radiation on cell growth and protein synthesis in yeast. (C.H.)« less

Design and Mechanism of Tetrahydrothiophene-based GABA Aminotransferase Inactivators

PubMed Central

Le, Hoang V.; Hawker, Dustin D.; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L.; Silverman, Richard B.

2015-01-01

Low levels of γ-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of γ-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally-restricted, tetrahydrothiophene-based GABA analogs with a properly-positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is eight times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bond interactions with Arg-192, a π-π interaction with Phe-189, and a weak nonbonded S···O=C interaction with Glu-270, thereby inactivating the enzyme. PMID:25781189

The use of chlorine dioxide for the inactivation of copepod zooplankton in drinking water treatment.

PubMed

Lin, Tao; Chen, Wei; Cai, Bo

2014-01-01

The presence of zooplankton in drinking water treatment system may cause a negative effect on the aesthetic value of drinking water and may also increase the threat to human health due to they being the carriers of bacteria. Very little research has been done on the effects of copepod inactivation and the mechanisms involved in this process. In a series of bench-scale experiments we used a response surface method to assess the sensitivity of copepod to inactivation when chlorine dioxide (ClO₂) was used as a disinfectant. We also assessed the effects of the ClO₂dosage, exposure time, organic matter concentration and temperature. Results indicated that the inactivation rate improved with increasing dosage, exposure time and temperature, whereas it decreased with increasing organic matter concentration. Copepod inactivation was more sensitive to the ClO₂dose than that to the exposure time, while being maintained at the same Ct-value conditions. The activation energy at different temperatures revealed that the inactivation of copepods with ClO₂was temperature-dependent. The presence of organic matter resulted in a lower available dose as well as a shorter available exposure time, which resulted in a decrease in inactivation efficiency.

Design and Mechanism of Tetrahydrothiophene-Based γ-Aminobutyric Acid Aminotransferase Inactivators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le, Hoang V.; Hawker, Dustin D.; Wu, Rui

Low levels of gamma-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinsons disease, Alzheimers disease, Huntingtons disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the bloodbrain barrier and inhibit the activity of gamma-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. Onemore » compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a pi-pi interaction with Phe-189, and a weak nonbonded (SO)-O-...=C interaction with Glu-270, thereby inactivating the enzyme.« less

Design and mechanism of tetrahydrothiophene-based γ-aminobutyric acid aminotransferase inactivators.

PubMed

Le, Hoang V; Hawker, Dustin D; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L; Silverman, Richard B

2015-04-08

Low levels of γ-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson's disease, Alzheimer's disease, Huntington's disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of γ-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a π-π interaction with Phe-189, and a weak nonbonded S···O═C interaction with Glu-270, thereby inactivating the enzyme.

[Effect of various factors on ozone inactivating Giardia in water].

PubMed

Ran, Zhi-Lin; Li, Shao-Feng; Huang, Jun-Li; Yuan, Yi-Xing; Cui, Chong-Wei

2010-06-01

In order to study the effect of O3 inactivating Giardia in water, different factors (CT value, pH, temperature, turbidity, organic content and inorganic ions) which might influence the inactivation were investigated by using fluorescence staining method. The results indicated that the whole process of O3 inactivating Giardia could be divided into two periods, the inactivated rate in log phase was significantly faster than it in the slow phase [k1 = (5.64 +/- 0.023) x 10(-1) mg x min, k2 = (2.72 +/- 0.002) x 10(-2) mg x min, k1 > k2]. When the turbidity was 0.1 to 20. 0NTU, temperature was 5 to 35 degrees C, pH was 6.0 to 9.0, HA content was 0.5 to 10.0 mg/L, the turbidity was lower, the higher inactivating ratio could be received. With the increasing of temperature, the inactivating effect was decreased. The ability of O3 inactivating Giardia was stronger under acidic condition than it was in alkali circumstance. When the reaction system contained higher concentration of organics, the competition reaction might take place between Giardia and organics with O3, which might reduce inactivation ratio. The sequence of affecting disinfectant ability of O3 was NO3- > None > SO4(2-) > HCO3-, while inorganic cations (Ca2+, Mg2+ and Cu2+) promoted the inactive reaction to a certain extent. If the CT value of O3 was more than 15.0 min x mg/L, the ratio of inactivation could exceed 99.0% during disinfecting drinking water.

Radiation survival of two nalidixic acid resistant strains of Salmonella typhimurium in various media

NASA Astrophysics Data System (ADS)

Shamsuzzaman, Kazi; Goodwin, Marlene; George, Ian; Singh, Harwant

Radiation doses required for 90% inactivation, the D10 values, have been determined for two nalidixic acid-resistant strains of Salmonella typhimurium, Nal R ATCC 13311 and K1-2B, in different media. The D10 values were 0.20, 0.57 and 0.53 kGy for the ATCC 13311 strain, and were 0.21, 0.4 and 0.32 kGy for the K1-2B strain, in phosphate buffer, in nutrient broth and on chicken drumsticks, respectively. Since these two strains have radiation sensitivity similar to several Salmonella serotypes reported in the literature, they are good indicator organisms for use in studies on the effect of irradiation on Salmonella in foods that might frequently be contaminated with such organisms.

Regression Model for MODTRAN with Applications to Inactivation of Microbes Suspended in the Atmosphere by Solar Ultraviolet Radiation

DTIC Science & Technology

2012-05-01

mixed vegetation): 0.007 (0.017) For materials tested, • The albedo levels of old grass, dead grass, burnt grass, and maple leaf at 300 nm were...as 0.016-0.017 over vegetation, 0.04-0.05 over bare fertile soil, and 0.07-0.10 over concrete (autobahn, Germany). The albedo over dry bright sand

Wnt Inactivation for Liver Cancer Therapy | Center for Cancer Research

Cancer.gov

Hepatocellular carcinoma (HCC) is the fifth most common and third most deadly type of cancer in the world. The majority of cases occur in Asia and Africa, resulting in most cases being diagnosed only at advanced stages of the disease when drug resistance is high. HCC typically follows damage to the liver such as cirrhosis, making radiation and chemotherapy a more challenging

Efficacy of Two Peroxygen-Based Disinfectants for Inactivation of Cryptosporidium parvum Oocysts

PubMed Central

Quilez, Joaquin; Sanchez-Acedo, Caridad; Avendaño, Catalina; del Cacho, Emilio; Lopez-Bernad, Fernando

2005-01-01

Two commercial peroxygen-based disinfectants containing hydrogen peroxide plus either peracetic acid (Ox-Virin) or silver nitrate (Ox-Agua) were tested for their ability to inactivate Cryptosporidium parvum oocysts. Oocysts were obtained from naturally infected goat kids and exposed to concentrations of 2, 5, and 10% Ox-Virin or 1, 3, and 5% Ox-Agua for 30, 60, and 120 min. In vitro excystation, vital dyes (4′,6′-diamidino-2-phenylindole and propidium iodide), and infectivity in neonatal BALB/c mice were used to assess the viability and infectivity of control and disinfectant-treated oocysts. Both disinfectants had a deleterious effect on the survival of C. parvum oocysts, since disinfection significantly reduced and in some cases eliminated their viability and infectivity. When in vitro assays were compared with an infectivity assay as indicators of oocyst inactivation, the excystation assay showed 98.6% inactivation after treatment with 10% Ox-Virin for 60 min, while the vital-dye assay showed 95.2% inactivation and the infectivity assay revealed 100% inactivation. Treatment with 3% Ox-Agua for 30 min completely eliminated oocyst infectivity for mice, although we were able to observe only 74.7% inactivation as measured by excystation assays and 24.3% with vital dyes (which proved to be the least reliable method for predicting C. parvum oocyst viability). These findings indicate the potential efficacy of both disinfectants for C. parvum oocysts in agricultural settings where soil, housing, or tools might be contaminated and support the argument that in comparison to the animal infectivity assay, vital-dye and excystation methods overestimate the viability of oocysts following chemical disinfection. PMID:15870337

MPLEx: a method for simultaneous pathogen inactivation and extraction of samples for multi-omics profiling.

PubMed

Burnum-Johnson, Kristin E; Kyle, Jennifer E; Eisfeld, Amie J; Casey, Cameron P; Stratton, Kelly G; Gonzalez, Juan F; Habyarimana, Fabien; Negretti, Nicholas M; Sims, Amy C; Chauhan, Sadhana; Thackray, Larissa B; Halfmann, Peter J; Walters, Kevin B; Kim, Young-Mo; Zink, Erika M; Nicora, Carrie D; Weitz, Karl K; Webb-Robertson, Bobbie-Jo M; Nakayasu, Ernesto S; Ahmer, Brian; Konkel, Michael E; Motin, Vladimir; Baric, Ralph S; Diamond, Michael S; Kawaoka, Yoshihiro; Waters, Katrina M; Smith, Richard D; Metz, Thomas O

2017-01-26

The continued emergence and spread of infectious agents is of great concern, and systems biology approaches to infectious disease research can advance our understanding of host-pathogen relationships and facilitate the development of new therapies and vaccines. Molecular characterization of infectious samples outside of appropriate biosafety containment can take place only subsequent to pathogen inactivation. Herein, we describe a modified Folch extraction using chloroform/methanol that facilitates the molecular characterization of infectious samples by enabling simultaneous pathogen inactivation and extraction of proteins, metabolites, and lipids for subsequent mass spectrometry-based multi-omics measurements. This single-sample metabolite, protein and lipid extraction (MPLEx) method resulted in complete inactivation of clinically important bacterial and viral pathogens with exposed lipid membranes, including Yersinia pestis, Salmonella Typhimurium, and Campylobacter jejuni in pure culture, and Yersinia pestis, Campylobacter jejuni, and West Nile, MERS-CoV, Ebola, and influenza H7N9 viruses in infection studies. In addition, >99% inactivation, which increased with solvent exposure time, was also observed for pathogens without exposed lipid membranes including community-associated methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and vegetative cells, and adenovirus type 5. The overall pipeline of inactivation and subsequent proteomic, metabolomic, and lipidomic analyses was evaluated using a human epithelial lung cell line infected with wild-type and mutant influenza H7N9 viruses, thereby demonstrating that MPLEx yields biomaterial of sufficient quality for subsequent multi-omics analyses. Based on these experimental results, we believe that MPLEx will facilitate systems biology studies of infectious samples by enabling simultaneous pathogen inactivation and multi-omics measurements from a single specimen with high success for pathogens with exposed lipid membranes.

MPLEx: A method for simultaneous pathogen inactivation and extraction of samples for multi-omics profiling

PubMed Central

Burnum-Johnson, Kristin E.; Kyle, Jennifer E.; Eisfeld, Amie J.; Casey, Cameron P.; Stratton, Kelly G.; Gonzalez, Juan F.; Habyarimana, Fabien; Negretti, Nicholas M.; Sims, Amy C.; Chauhan, Sadhana; Thackray, Larissa B.; Halfmann, Peter J.; Walters, Kevin B.; Kim, Young-Mo; Zink, Erika M.; Nicora, Carrie D.; Weitz, Karl K.; Webb-Robertson, Bobbie-Jo M.; Nakayasu, Ernesto S.; Ahmer, Brian; Konkel, Michael E.; Motin, Vladimir; Baric, Ralph S.; Diamond, Michael S.; Kawaoka, Yoshihiro; Waters, Katrina M.; Smith, Richard D.; Metz, Thomas O.

2017-01-01

The continued emergence and spread of infectious agents is of great concern, and systems biology approaches to infectious disease research can advance our understanding of host-pathogen relationships and facilitate the development of new therapies and vaccines. Molecular characterization of infectious samples outside of appropriate biosafety containment can take place only subsequent to pathogen inactivation. Herein, we describe a modified Folch extraction using chloroform/methanol that facilitates the molecular characterization of infectious samples by enabling simultaneous pathogen inactivation and extraction of proteins, metabolites, and lipids for subsequent mass spectrometry-based multi-omics measurements. This single-sample metabolite, protein and lipid extraction (MPLEx) method resulted in complete inactivation of clinically important bacterial and viral pathogens with exposed lipid membranes, including Yersinia pestis, Salmonella Typhimurium, and Campylobacter jejuni in pure culture, and Yersinia pestis, Campylobacter jejuni, and West Nile, MERS-CoV, Ebola, and influenza H7N9 viruses in infection studies. In addition, >99% inactivation, which increased with solvent exposure time, was also observed for pathogens without exposed lipid membranes including community-associated methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and vegetative cells, and adenovirus type 5. The overall pipeline of inactivation and subsequent proteomic, metabolomic, and lipidomic analyses was evaluated using a human epithelial lung cell line infected with wild-type and mutant influenza H7N9 viruses, thereby demonstrating that MPLEx yields biomaterial of sufficient quality for subsequent multi-omics analyses. Based on these experimental results, we believe that MPLEx will facilitate systems biology studies of infectious samples by enabling simultaneous pathogen inactivation and multi-omics measurements from a single specimen with high success for pathogens with exposed lipid membranes. PMID:28091625

Biological Sterilization of Returned Mars Samples

NASA Technical Reports Server (NTRS)

Allen, C. C.; Albert, F. G.; Combie, J.; Bodnar, R. J.; Hamilton, V. E.; Jolliff, B. L.; Kuebler, K.; Wang, A.; Lindstrom, D. J.; Morris, P. A.

1999-01-01

Martian rock and soil, collected by robotic spacecraft, will be returned to terrestrial laboratories early in the next century. Current plans call for the samples to be immediately placed into biological containment and tested for signs of present or past life and biological hazards. It is recommended that "Controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized." While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. The sterilization method should be capable of destroying a wide range of organisms with minimal effects on the geologic samples. A variety of biological sterilization techniques and materials are currently in use, including dry heat, high pressure steam, gases, plasmas and ionizing radiation. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. Many commercial sterilizers use Co-60 , which emits gamma photons of 1.17 and 1.33 MeV. Absorbed doses of approximately 1 Mrad (10(exp 8) ergs/g) destroy most bacteria. This study investigates the effects of lethal doses of Co-60 gamma radiation on materials similar to those anticipated to be returned from Mars. The goals are to determine the gamma dose required to kill microorganisms in rock and soil samples and to determine the effects of gamma sterilization on the samples' isotopic, chemical and physical properties. Additional information is contained in the original extended abstract.

Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

PubMed Central

Fröhling, Antje; Schlüter, Oliver

2015-01-01

Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfill the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results. The aim of this study was to compare the inactivation effects of peracetic acid (PAA), ozonated water (O3), and cold atmospheric pressure plasma (CAPP) on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s) with 0.25% PAA at 10°C, and after treatment (10 s) with 3.8 mg l−1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l−1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process parameters. PMID:26441874

Use of radiation in biomaterials science

NASA Astrophysics Data System (ADS)

Benson, Roberto S.

2002-05-01

Radiation is widely used in the biomaterials science for surface modification, sterilization and to improve bulk properties. Radiation is also used to design of biochips, and in situ photopolymerizable of bioadhesives. The energy sources most commonly used in the irradiation of biomaterials are high-energy electrons, gamma radiation, ultraviolet (UV) and visible light. Surface modification involves placement of selective chemical moieties on the surface of a material by chemical reactions to improve biointeraction for cell adhesion and proliferation, hemocompatibility and water absorption. The exposure of a polymer to radiation, especially ionizing radiation, can lead to chain scission or crosslinking with changes in bulk and surface properties. Sterilization by irradiation is designed to inactivate most pathogens from the surface of biomedical devices. An overview of the use of gamma and UV radiation to improve surface tissue compatibility, bulk properties and surface properties for wear resistance, formation of hydrogels and curing dental sealants and bone adhesives is presented. Gamma and vacuum ultraviolet (VUV) irradiated ultrahigh molecular weight polyethylene (UHMWPE) exhibit improvement in surface modulus and hardness. The surface modulus and hardness of UHMWPE showed a dependence on type of radiation, dosage and processing. VUV surface modified e-PTFE vascular grafts exhibit increases in hydrophilicity and improvement towards adhesion of fibrin glue.

Demonstration of a novel Xp22.2 microdeletion as the cause of familial extreme skewing of X-inactivation utilizing case-parent trio SNP microarray analysis.

PubMed

Mason, Jane A; Aung, Hnin T; Nandini, Adayapalam; Woods, Rickie G; Fairbairn, David J; Rowell, John A; Young, David; Susman, Rachel D; Brown, Simon A; Hyland, Valentine J; Robertson, Jeremy D

2018-05-01

We report a kindred referred for molecular investigation of severe hemophilia A in a young female in which extremely skewed X-inactivation was observed in both the proband and her clinically normal mother. Bidirectional Sanger sequencing of all F8 gene coding regions and exon/intron boundaries was undertaken. Methylation-sensitive restriction enzymes were utilized to investigate skewed X-inactivation using both a classical human androgen receptor (HUMARA) assay, and a novel method targeting differential methylation patterns in multiple informative X-chromosome SNPs. Illumina Whole-Genome Infinium microarray analysis was performed in the case-parent trio (proband and both parents), and the proband's maternal grandmother. The proband was a cytogenetically normal female with severe hemophilia A resulting from a heterozygous F8 pathogenic variant inherited from her similarly affected father. No F8 mutation was identified in the proband's mother, however, both the proband and her mother both demonstrated completely skewed X-chromosome inactivation (100%) in association with a previously unreported 2.3 Mb deletion at Xp22.2. At least three disease-associated genes (FANCB, AP1S2, and PIGA) were contained within the deleted region. We hypothesize that true "extreme" skewing of X-inactivation (≥95%) is a rare occurrence, but when defined correctly there is a high probability of finding an X-chromosome disease-causing variant or larger deletion resulting in X-inactivation through a survival disadvantage or cell lethal mechanism. We postulate that the 2.3 Mb Xp22.2 deletion identified in our kindred arose de novo in the proband's mother (on the grandfather's homolog), and produced extreme skewing of X-inactivation via a "cell lethal" mechanism. We introduce a novel multitarget approach for X-inactivation analysis using multiple informative differentially methylated SNPs, as an alternative to the classical single locus (HUMARA) method. We propose that for females with unexplained severe phenotypic expression of an X-linked recessive disorder trio-SNP microarray should be undertaken in combination with X-inactivation analysis. © 2018 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.

Positron emitter labeled enzyme inhibitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline andmore » L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.« less

Inactivation of bacteria using dc corona discharge: role of ions and humidity.

PubMed

Dobrynin, Danil; Friedman, Gary; Fridman, Alexander; Starikovskiy, Andrey

2011-10-01

Here we present the results of an experimental study of the effect of ions produced in a dc corona discharge on inactivation of bacteria on the surface of agarose gel. Both positive and negative corona discharges in various gases at different humidities were studied. The measurements in air, O(2), N(2), Ar and He mixtures show that there is no inactivation in pure N(2), pure O(2) and an N(2)-H(2)O mixture. The best results were achieved in the case of direct treatment, when discharge was ignited in oxygen and water-containing mixtures. We show that neither UV radiation, ozone or H(2)O(2) nor other neutral active species alone produced by corona have an effect on bacteria viability. It is shown that the main role of charged particles may be related to the faster transport of active peroxide species-cluster ions OH(-)(H(2)O)(n) and H(3)O(+)(H(2)O)(n). The efficiency of these radicals is much higher than that of the oxygen radicals and ions (including [Formula: see text] and O(3)) and that of nitrogen and argon ions.

Decontamination Efficacy of Ultraviolet Radiation against Biofilms of Common Nosocomial Bacteria.

PubMed

Tingpej, Pholawat; Tiengtip, Rattana; Kondo, Sumalee

2015-06-01

Ultraviolet radiation (UV) is commonly used to destroy microorganisms in the health-care environment. However, the efficacy of UV radiation against bacteria growing within biofilms has never been studied. To measure the sterilization effectiveness of UV radiation against common healthcare associated pathogens growing within biofilms. Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Streptococcus epidermidis, Escherichia coli, ESBL-producing E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii were cultivated in the Calgary Biofilm Device. Their biofilms were placed 50 cm from the UV lamp within the Biosafety Cabinet. Viability test, crystal violet assay and a scanning electron microscope were used to evaluate the germicidal efficacy. Within 5 minutes, UV radiation could kill S. aureus, MRSA, S. epidermidis, A. baumannii and ESBL-producing E. coli completely while it required 20 minutes and 30 minutes respectively to kill E. coli and P. aeruginosa. However, the amounts of biomass and the ultrastructure between UV-exposed biofilms and controls were not significantly different. UV radiation is effective in inactivating nosocomial pathogens grown within biofilms, but not removing biofilms and EPS. The biofilm of P. aeruginosa was the most durable.

Assessing the effectiveness of low-pressure ultraviolet light for inactivating Mycobacterium avium complex (MAC) micro-organisms

EPA Science Inventory

Aims: To assess low-pressure ultraviolet light (LP-UV) inactivation kinetics of Mycobacterium avium complex (MAC) strains in a water matrix using collimated beam apparatus. Methods and Results: Strains of M. avium (n = 3) and Mycobacterium intracellulare (n = 2) were exposed t...

West Nile virus in plasma is highly sensitive to methylene blue-light treatment.

PubMed

Mohr, Harald; Knüver-Hopf, Joseph; Gravemann, Ute; Redecker-Klein, Anette; Müller, Thomas H

2004-06-01

The epidemic of West Nile virus (WNV) in the US resulted in cases of transfusion-transmitted WNV. Effective pathogen reduction methods could have removed this infectious agent from the blood supply We have evaluated the efficacy of photodynamic treatment of fresh frozen plasma (FFP) with methylene blue (MB), a decontamination method applied in several European countries. FFP units (300 ml each) were spiked with WNV. MB was added, and the units were illuminated with white or monochromatic yellow light. WNV infectivity was determined by bioassay. WNV-RNA was quantitated by real-time PCR. The inactivation of WNV was investigated under standard and under suboptimal conditions, respectively. In addition, rechallenge experiments with multiple addition of WNV at maximal load (approx. 105 CFU/ml) and repeated illumination without replenishing MB were performed. Complete inactivation of WNV was achieved by MB (0.8-1 mmol/l) and illumination with white light (30,000-45,000 Lux) within 2 min. White yellow light 20-40 J/cm(2) (2.5-5 min) were sufficient for inactivation by 5.75 log10-steps. The rechallenge experiments revealed the substantial reserve capacity of the procedure to inactivate WNV. Quantitative PCR indicated that the viral RNA was rapidly destroyed. All experimental data demonstrate the enormous potency of phototreatment with MB to inactivate WNV in plasma.

Extracting survival parameters from isothermal, isobaric, and "iso-concentration" inactivation experiments by the "3 end points method".

PubMed

Corradini, M G; Normand, M D; Newcomer, C; Schaffner, D W; Peleg, M

2009-01-01

Theoretically, if an organism's resistance can be characterized by 3 survival parameters, they can be found by solving 3 simultaneous equations that relate the final survival ratio to the lethal agent's intensity. (For 2 resistance parameters, 2 equations will suffice.) In practice, the inevitable experimental scatter would distort the results of such a calculation or render the method unworkable. Averaging the results obtained with more than 3 final survival ratio triplet combinations, determined in four or more treatments, can remove this impediment. This can be confirmed by the ability of a kinetic inactivation model derived from the averaged parameters to predict survival patterns under conditions not employed in their determination, as demonstrated with published isothermal survival data of Clostridium botulinum spores, isobaric data of Escherichia coli under HPP, and Pseudomonas exposed to hydrogen peroxide. Both the method and the underlying assumption that the inactivation followed a Weibull-Log logistic (WeLL) kinetics were confirmed in this way, indicating that when an appropriate survival model is available, it is possible to predict the entire inactivation curves from several experimental final survival ratios alone. Where applicable, the method could simplify the experimental procedure and lower the cost of microbial resistance determinations. In principle, the methodology can be extended to deteriorative chemical reactions if they too can be characterized by 2 or 3 kinetic parameters.

FAST TRACK COMMUNICATION: Selective inactivation of micro-organisms with near-infrared femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Tsen, K. T.; Tsen, Shaw-Wei D.; Sankey, Otto F.; Kiang, Juliann G.

2007-11-01

We demonstrate an unconventional and revolutionary method for selective inactivation of micro-organisms by using near-infrared femtosecond laser pulses. We show that if the wavelength and pulse width of the excitation femtosecond laser are appropriately selected, there exists a window in power density that enables us to achieve selective inactivation of target viruses and bacteria without causing cytotoxicity in mammalian cells. This strategy targets the mechanical (vibrational) properties of micro-organisms, and thus its antimicrobial efficacy is likely unaffected by genetic mutation in the micro-organisms. Such a method may be effective against a wide variety of drug resistant micro-organisms and has broad implications in disinfection as well as in the development of novel treatments for viral and bacterial pathogens.

High pressure inactivation of Brettanomyces bruxellensis in red wine.

PubMed

van Wyk, Sanelle; Silva, Filipa V M

2017-05-01

Brettanomyces bruxellensis ("Brett") is a major spoilage concern for the wine industry worldwide, leading to undesirable sensory properties. Sulphur dioxide, is currently the preferred method for wine preservation. However, due to its negative effects on consumers, the use of new alternative non-thermal technologies are increasingly being investigated. The aim of this study was to determine and model the effect of high pressure processing (HPP) conditions and yeast strain on the inactivation of "Brett" in Cabernet Sauvignon wine. Processing at 200 MPa for 3 min resulted in 5.8 log reductions. However higher pressure is recommended to achieve high throughput in the wine industry, for example >6.0 log reductions were achieved after 400 MPa for 5 s. The inactivation of B. bruxellensis is pressure and time dependent, with increased treatment time and pressure leading to increased yeast inactivation. It was also found that yeast strain had a significant effect on HPP inactivation, with AWRI 1499 being the most resistant strain. The Weibull model successfully described the HPP "Brett" inactivation. HPP is a viable alternative for the inactivation of B. bruxellensis in wine, with the potential to reduce the industry's reliance on sulphur dioxide. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relative Biologic Effectiveness (RBE) of 50 kV X-rays Measured in a Phantom for Intraoperative Tumor-Bed Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Qi; Schneider, Frank; Ma, Lin

Purpose: Intraoperative radiation therapy (IORT) with low-energy x-rays is used to treat the tumor bed during breast-conserving surgery. The purpose was to determine the relative biologic effectiveness (RBE) of 50-kV x-rays for inactivation of cells irradiated in a tumor-bed phantom. Methods and Materials: The RBE was determined for clonogenic inactivation of human tumor and normal cells (MCF7, human umbilical vein endothelial cells, normal skin fibroblasts), and hamster V79 cells. The 50-kV x-rays from the Intrabeam machine (Carl Zeiss Surgical) with a spherical 4-cm applicator were used. Cells were irradiated in a water-equivalent phantom at defined distances (8.1-22.9 mm) from themore » applicator surface. The 50-kV x-rays from a surface therapy machine (Dermopan, Siemens) were included for comparison; 6-MV x-rays were used as reference radiation. Results: At 8.1-mm depth in the phantom (dose rate 15.1 Gy/h), mean RBE values of 50-kV x-rays from Intrabeam were 1.26 to 1.42 for the 4 cell types at doses yielding surviving fractions in the range of 0.01 to 0.5. Confidence intervals were in the range of 1.2 and 1.5. Similar RBE values were found for 50-kV x-rays from Dermopan for V79 (1.30, CI 1.25-1.36, P=.74) and GS4 (1.42, CI 1.30-1.54, P=.67). No significant dependence of RBE on dose was found for Intrabeam, but RBE decreased at a larger distance (12.7 mm; 9.8 Gy/h). Conclusions: An increased clinically relevant RBE was found for cell irradiation with Intrabeam at depths in the tumor bed targeted by IORT. The reduced RBE values at larger distances may be related to increased repair of sublethal damage during protracted irradiation or to hardening of the photon beam energy.« less

Unfolding and inactivation during thermal denaturation of an enzyme that exhibits phytase and acid phosphatase activities.

PubMed

Wang, Xiao-Yun; Meng, Fan-Guo; Zhou, Hai-Meng

2004-03-01

The thermostability of an enzyme that exhibits phytase and acid phosphatase activities was studied. Kinetics of inactivation and unfolding during thermal denaturation of the enzyme were compared. The loss of phytase activity on thermal denaturation is most suggestive of a reversible process. As for acid phosphatase activities, an interesting phenomenon was observed; there are two phases in thermal inactivation: when the temperature was between 45 and 50 degrees C, the thermal inactivation could be characterized as an irreversible inactivation which had some residual activity and when the temperature was above 55 degrees C, the thermal inactivation could be characterized as an irreversible process which had no residual activity. The microscopic rate constants for the free enzyme and substrate-enzyme complex were determined by Tsou's method [Adv. Enzymol. Relat. Areas Mol. Biol. 61 (1988) 381]. Fluorescence analyses indicate that when the enzyme was treated at temperatures below 60 degrees C for 60 min, the conformation of the enzyme had no detectable change; when the temperatures were above 60 degrees C, some fluorescence red-shift could be observed with a decrease in emission intensity. The inactivation rates (k(+0)) of free enzymes were faster than those of conformational changes during thermal denaturation at the same temperature. The rapid inactivation and slow conformational changes of phytase during thermal denaturation suggest that inactivation occurs before significant conformational changes of the enzyme, and the active site of this enzyme is situated in a relatively fragile region which makes the active site more flexible than the molecule as a whole.

Effects of UVB radiation on Photosynthesis Activity of Wolffia arrhiza as Probed by Chlorophyll Fluorescence Transient

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Chen, Kun; Liu, Yongding

UV radiation is one major environmental stress for growth of Wolffia arrhiza which is regarded as a good candidate producer for establishing CELSS during extraterrestrial colonization and spaceflight. In this study, we found that UVB radiation inhibited photosynthetic CO2 assimilation activity significantly, and the content of chlorophyll a, chlorophyll b and carotenoids decreased obviously when plants were exposed to UVB radiation for 6 h. High UVB radiation also declined the quantum yield of primary photochemistry (φPo), the quantum yield for electron transport (φEo) and the efficiency per trapped excitation (ψo) in the cells of Wolffia arrhiza simultaneously, while the amount of active PSII reaction centers per excited cross section (RC/CS) and the total number of active reaction center per absorption (RC/ABS) had the same changes under UV-B radiation stress. These results indicated that the effects of UV- B radiation on photosynthesis of Wolffia arrhiza maybe functioned by inhibition the electron transport and inactivation of reaction centers, but the inhibition maybe happen in more than one site in photosynthetic apparatus which is different to that in salt adaptation.

Radiosensitization: enhancing the radiation inactivation of foodborne bacteria

NASA Astrophysics Data System (ADS)

Borsa, J.; Lacroix, M.; Ouattara, B.; Chiasson, F.

2004-09-01

Irradiation of meat products to kill pathogens can be limited by radiation-induced detriment of sensory quality. Since such detriment is directly related to dose, one approach to reduce it is by devising means to lower the dose of radiation required for processing. Increasing the radiation sensitivity of the target microorganisms would lower the dose required for a given level of microbial kill. In this work, the radiation sensitivities of inoculated Escherichia coli and Salmonella typhi in ground beef were examined under a variety of conditions. Results showed that specific manipulations of treatment conditions significantly increased the radiation sensitivity of the test organisms, ranging from a few percent to several-fold reduction in D10. In particular, radiation sensitization could be effected by certain additives, including carvacrol, thymol and trans-cinnamaldehyde, and also by certain compositions of modified atmosphere in the package headspace. A combination of additives and modified atmosphere effected a greater radiosensitization effect than could be achieved by either factor applied alone. Radiosensitization could be demonstrated with irradiation of either fresh or frozen ground meat. The radiosensitization phenomenon may be of practical utility in enhancing the technical effectiveness and feasibility of irradiation of a variety of meat and other food products.

Ultraviolet-C efficacy against a norovirus surrogate and hepatitis A virus on a stainless steel surface.

PubMed

Park, Shin Young; Kim, An-Na; Lee, Ki-Hoon; Ha, Sang-Do

2015-10-15

In this study, the effects of 10-300 mWs/cm(2) of ultraviolet radiation (UV-C) at 260 nm were investigated for the inactivation of two foodborne viruses: murine norovirus-1 (MNV-1; a human norovirus [NoV] surrogate) and hepatitis A virus (HAV). We used an experimentally contaminated stainless steel surface, a common food-contact surface, to examine the effects of low doses of UV-C radiation on MNV-1 and HAV titers. The modified Gompertz equation was used to generate non-linear survival curves and calculate dR-values as the UV-C dose of 90% reduction for MNV-1 (R(2)=0.95, RMSE=0.038) and HAV (R(2)=0.97, RMSE=0.016). Total MNV-1 and HAV titers significantly decreased (p<0.05) with higher doses of UV-C. MNV-1 and HAV were reduced to 0.0-4.4 and 0.0-2.6 log10PFU/ml, respectively, on the stainless steel surfaces by low-dose UV-C treatment. The dR-value, 33.3 mWs/cm(2) for MNV-1 was significantly (p<0.05) lower than 55.4 mWs/cm(2) of HAV. Therefore, the present study shows that HAV is more resistant to UV-C radiation than MNV-1. These data suggest that low doses of UV-C light on food contact surfaces could be effective to inactivate human NoV and HAV in restaurant, institutional, and industrial kitchens and facilities. Copyright © 2015 Elsevier B.V. All rights reserved.

Knockdown of TC-1 enhances radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway.

PubMed

Wu, Dapeng; Li, Lei; Yan, Wei

2016-04-15

Thyroid cancer 1 (TC-1, C8ofr4) is widely expressed in vertebrates and associated with many kinds of tumors. Previous studies indicated that TC-1 functions as a positive regulator in the Wnt/β-catenin signaling pathway in non-small cell lung cancer (NSCLC). However, its exact role and regulation mechanism in radiosensitivity of NSCLC are still unclear. The expression level of TC-1 was measured by qRT-PCR and western blot in NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to TC-1 knockdown or/and radiation were determined by MTT assay and flow cytometry, respectively. The activation of the Wnt/β-catenin signaling pathway was further examined by western blotin vitroandin vivo Compared to TC-1 siRNA or radiotherapy alone, TC-1 silencing combined with radiation inhibited cell proliferation and induced apoptosis in NSCLC cell lines by inactivating of the Wnt/β-catenin signaling pathway. Furthermore, inhibition of the Wnt/β-catenin signaling pathway by XAV939, a Wnt/β-catenin signaling inhibitor, contributed to proliferation inhibition and apoptosis induction in NSCLC A549 cells. Combinative treatment of A549 xenografts with TC-1 siRNA and radiation caused significant tumor regression and inactivation of the Wnt/β-catenin signaling pathway relative to TC-1 siRNA or radiotherapy alone. The results fromin vitroandin vivostudies indicated that TC-1 silencing sensitized NSCLC cell lines to radiotherapy through the Wnt/β-catenin signaling pathway. © 2016. Published by The Company of Biologists Ltd.

Knockdown of TC-1 enhances radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway

PubMed Central

Wu, Dapeng; Li, Lei; Yan, Wei

2016-01-01

ABSTRACT Thyroid cancer 1 (TC-1, C8ofr4) is widely expressed in vertebrates and associated with many kinds of tumors. Previous studies indicated that TC-1 functions as a positive regulator in the Wnt/β-catenin signaling pathway in non-small cell lung cancer (NSCLC). However, its exact role and regulation mechanism in radiosensitivity of NSCLC are still unclear. The expression level of TC-1 was measured by qRT-PCR and western blot in NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to TC-1 knockdown or/and radiation were determined by MTT assay and flow cytometry, respectively. The activation of the Wnt/β-catenin signaling pathway was further examined by western blot in vitro and in vivo. Compared to TC-1 siRNA or radiotherapy alone, TC-1 silencing combined with radiation inhibited cell proliferation and induced apoptosis in NSCLC cell lines by inactivating of the Wnt/β-catenin signaling pathway. Furthermore, inhibition of the Wnt/β-catenin signaling pathway by XAV939, a Wnt/β-catenin signaling inhibitor, contributed to proliferation inhibition and apoptosis induction in NSCLC A549 cells. Combinative treatment of A549 xenografts with TC-1 siRNA and radiation caused significant tumor regression and inactivation of the Wnt/β-catenin signaling pathway relative to TC-1 siRNA or radiotherapy alone. The results from in vitro and in vivo studies indicated that TC-1 silencing sensitized NSCLC cell lines to radiotherapy through the Wnt/β-catenin signaling pathway. PMID:27029901

Painting analysis of chromosome aberrations induced by energetic heavy ions in human cells

NASA Astrophysics Data System (ADS)

Wu, H.; Hada, M.; Cucinotta, F. A.

Energetic heavy ions pose a great health risk to astronauts in extended ISS and future exploration missions High-LET heavy ions are particularly effective in causing various biological effects including cell inactivation genetic mutations and cancer induction Most of these biological endpoints are closely related to chromosomal damage which can be utilized as a biomarker for radiation insults Over the years we have studied chromosomal damage in human fibroblast epithelia and lymphocyte cells exposed in vitro to energetic charged particles generated at several accelerator facilities in the world Various fluorescence in situ hybridization painting techniques have been used to identify from only the telomere region of the chromosome to every chromosome in a human cell We will summarize the results of the investigations and discuss the unique radiation signatures and biomarkers for space radiation exposure

Inactivation of Salmonella enterica and Listeria monocytogenes in cantaloupe puree by high hydrostatic pressure with/without added ascorbic acid

USDA-ARS?s Scientific Manuscript database

The objective of this research was to evaluate and develop a method for inactivation of Salmonella enterica and Listeria monocytogenes in cantaloupe puree (CP) by high hydrostatic pressure (HHP). Cantaloupe being the most netted varieties of melons presents a greater risk of pathogen transmission. ...

75 FR 80798 - Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of Inventions...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-23

... Partially-Exclusive Licensing of Inventions Concerning an Inactivated Dengue Virus Vaccine and a Method and Kit for Detection of Dengue Virus AGENCY: Department of the Army, DoD. ACTION: Notice. SUMMARY... which issued July 3, 2001, entitled ``Inactivated Dengue Virus Vaccine,'' and U.S. Patent 6,190,859...

Comparison of proteomic profiles of serum, plasma, and modified media supplements used for cell culture and expansion

PubMed Central

Ayache, Saleh; Panelli, Monica C; Byrne, Karen M; Slezak, Stefanie; Leitman, Susan F; Marincola, Francesco M; Stroncek, David F

2006-01-01

Background The culture and expansion of human cells for clinical use requires the presence of human serum or plasma in culture media. Although these supplements have been extensively characterized in their chemical composition, only recently it has been possible to provide by high throughput protein analysis, a comprehensive profile of the soluble factors contributing to cell survival. This study analyzed and compared the presence of 100 proteins including chemokines, cytokines and soluble factors in six different types of media supplements: serum, plasma, recalcified plasma, heat inactivated serum, heat inactivated plasma and heat inactivated recalcified plasma. Methods Serum, plasma, recalcified plasma, and heat inactivated supplements were prepared from ten healthy subjects. The levels of 100 soluble factors were measured in each sample using a multiplexed ELISA assay and compared by Eisen hierarchical clustering analysis. Results A comparison of serum and plasma levels of soluble factors found that 2 were greater in plasma but 18 factors were greater in serum including 11 chemokines. The levels of only four factors differed between recalcified plasma and plasma. Heat inactivation had the greatest effect on soluble factors. Supervised Eisen hierarchical clustering indicated that the differences between heat inactivated supplements and those that were not were greater than the differences within these two groups. The levels of 36 factors differed between heat inactivated plasma and plasma. Thirty one of these factors had a lower concentration in heat inactivated plasma including 12 chemokines, 4 growth factors, 4 matrix metalloproteases, and 3 adhesion molecules. Heat inactivated decalcified plasma is often used in place of heat inactivated serum and the levels of 19 soluble factors differed between these two supplements. Conclusion Our report provides a comprehensive protein profile of serum, plasma recalcified plasma, and heat inactivated supplements. This profile represents a qualitative and quantitative database that can aid in the selection of the appropriate blood derived supplement for human cell cultures with special requirements. PMID:17020621

Metal-free virucidal effects induced by g-C3N4 under visible light irradiation: Statistical analysis and parameter optimization.

PubMed

Zhang, Chi; Li, Yi; Zhang, Wenlong; Wang, Peifang; Wang, Chao

2018-03-01

Waterborne viruses with a low infectious dose and a high pathogenic potential pose a serious risk for humans all over the world, calling for a cost-effective and environmentally-friendly inactivation method. Optimizing operational parameters during the disinfection process is a facile and efficient way to achieve the satisfactory viral inactivation efficiency. Here, the antiviral effects of a metal-free visible-light-driven graphitic carbon nitride (g-C 3 N 4 ) photocatalyst were optimized by varying operating parameters with response surface methodology (RSM). Twenty sets of viral inactivation experiments were performed by changing three operating parameters, namely light intensity, photocatalyst loading and reaction temperature, at five levels. According to the experimental data, a semi-empirical model was developed with a high accuracy (determination coefficient R 2  = 0.9908) and then applied to predict the final inactivation efficiency of MS2 (a model virus) after 180 min exposure to the photocatalyst and visible light illumination. The corresponding optimal values were found to be 199.80 mW/cm 2 , 135.40 mg/L and 24.05 °C for light intensity, photocatalyst loading and reaction temperature, respectively. Under the optimized conditions, 8 log PFU/mL of viruses could be completely inactivated by g-C 3 N 4 without regrowth within 240 min visible light irradiation. Our study provides not only an extended application of RSM in photocatalytic viral inactivation but also a green and effective method for water disinfection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radiation hydrolysate of tuna cooking juice with enhanced antioxidant properties

NASA Astrophysics Data System (ADS)

Choi, Jong-il; Sung, Nak-Yun; Lee, Ju-Woon

2012-08-01

Tuna protein hydrolysates are of increasing interest because of their potential application as a source of bioactive peptides. Large amounts of tuna cooking juice with proteins and extracts are produced during the process of tuna canning, and these cooking juice wastes cause environmental problems. Therefore, in this study, cooking juice proteins were hydrolyzed by irradiation for their utilization as functional additives. The degree of hydrolysis of tuna cooking juice protein increased from 0% to 15.1% at the absorbed doses of 50 kGy. To investigate the antioxidant activity of the hydrolysate, it was performed the ferric reducing antioxidant power (FRAP) assay, and the lipid peroxidation inhibitory and superoxide radical scavenging activities were measured. The FRAP values increased from 1470 μM to 1930 μM and IC50 on superoxide anion was decreased from 3.91 μg/mL to 1.29 μg/mL at 50 kGy. All of the antioxidant activities were increased in the hydrolysate, suggesting that radiation hydrolysis, which is a simple process that does not require an additive catalysts or an inactivation step, is a promising method for food and environmental industries.

Choosing the Active X: The Human Version of X Inactivation.

PubMed

Migeon, Barbara R

2017-12-01

Humans and rodents differ in how they carry out X inactivation (XI), the mammalian method to compensate for the different number of X chromosomes in males and females. Evolutionary changes in staging embryogenesis and in mutations within the XI center alter the process among mammals. The mouse model of XI is predicated on X counting and subsequently choosing the X to 'inactivate'. However, new evidence suggests that humans initiate XI by protecting one X in both sexes from inactivation by XIST, the noncoding RNA that silences the inactive X. This opinion article explores the question of how the active X is protected from silencing by its own Xist locus, and the possibility of different solutions for mouse and human. Copyright © 2017 Elsevier Ltd. All rights reserved.

Use of gamma radiation for inactivating Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in tahini halva.

PubMed

Osaili, Tareq M; Al-Nabulsi, Anas A; Aljaafreh, Taqwa F

2018-08-02

Tahini halva is a traditional sweet product that is consumed with bread in different countries. It is a low water activity (a w ) product basically made by mixing and cooking tahini, sugar, citric acid and Saponaria officinalis root extract together. Tahini halva maybe contaminated with foodborne pathogens during any stage of production from tahini and other raw ingredients, workers, environment or contact surfaces. The objectives of the study were to i) investigate the efficacy of gamma radiation to inactivate Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in tahini halva, ii) evaluate the effect of pre-irradiation storage (0, 7 and 30 days at 21 °C) of tahini halva on the sensitivity of these microorganisms toward gamma radiation, and iii) evaluate the effect of post-irradiation storage of tahini halva for up to 6 months on the their survival characteristics. Tahini halva samples were inoculated with Salmonella spp., E. coli O157:H7 and L. monocytogenes separately then stored at 21 °C for 0, 7 and 30 days prior to irradiation at 0-4 KGy and for up to 6 months after irradiation at 4 KGy. Salmonella spp. were the most irradiation resistance among the tested microorganisms. Irradiation (0.8-4.0 KGy) reduced the bacteria in samples stored for 0, 7 and 30 days pre-irradiation in the range of 0.43-2.11, 0.45-2.68 and 0.52-2.7 log 10  CFU/g for Salmonella spp., 0.55-3.08, 0.66-3.00 and 0.60-2.80 log 10  CFU/g for E. coli O157:H7, and 0.69-2.96, 0.86-4.30, 0.62-3.29 log 10  CFU/g for L. monocytogenes, respectively. The D 10 -value, the irradiation dose needed to inactivate 1 log 10 of pathogen, was 1.83, 1.47 and 1.50 KGy for Salmonella spp., 1.28, 1.32 and 1.48 KGy for E. coli O157:H7, and 1.33, 0.94 and 1.27 KGy for L. monocytogenes in pre-irradiation stored samples for 0, 7 and 30 days, respectively. Post-irradiation storage was efficient in decreasing the levels of the microorganisms ca. ≥2 log 10  CFU/g in the first month and to undetected level after the second month of storage but enrichment results showed that Salmonella spp. and L. monocytogenes were detected in the samples until of the end of storage period. The study demonstrates that gamma radiation can be applied to inactivate of foodborne pathogens in tahini halva. Irradiation dose at 4 KGy can reduce Salmonella spp., E. coli O157:H7 and L. monocytogenes in tahini halva by 2-3 log 10  CFU/g. Storage of tahini halva before or after irradiation may reduce the risk of foodborne pathogens in the product. Copyright © 2018 Elsevier B.V. All rights reserved.

Significance of Inactivated Genes in Leukemia: Pathogenesis and Prognosis

PubMed Central

Heidari, Nazanin; Abroun, Saeid; Bertacchini, Jessika; Vosoughi, Tina; Rahim, Fakher; Saki, Najmaldin

2017-01-01

Epigenetic and genetic alterations are two mechanisms participating in leukemia, which can inactivate genes involved in leukemia pathogenesis or progression. The purpose of this review was to introduce various inactivated genes and evaluate their possible role in leukemia pathogenesis and prognosis. By searching the mesh words “Gene, Silencing AND Leukemia” in PubMed website, relevant English articles dealt with human subjects as of 2000 were included in this study. Gene inactivation in leukemia is largely mediated by promoter’s hypermethylation of gene involving in cellular functions such as cell cycle, apoptosis, and gene transcription. Inactivated genes, such as ASPP1, TP53, IKZF1 and P15, may correlate with poor prognosis in acute lymphoid leukemia (ALL), chronic lymphoid leukemia (CLL), chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML), respectively. Gene inactivation may play a considerable role in leukemia pathogenesis and prognosis, which can be considered as complementary diagnostic tests to differentiate different leukemia types, determine leukemia prognosis, and also detect response to therapy. In general, this review showed some genes inactivated only in leukemia (with differences between B-ALL, T-ALL, CLL, AML and CML). These differences could be of interest as an additional tool to better categorize leukemia types. Furthermore; based on inactivated genes, a diverse classification of Leukemias could represent a powerful method to address a targeted therapy of the patients, in order to minimize side effects of conventional therapies and to enhance new drug strategies. PMID:28580304

Evaluation of FTA paper and phenol for storage, extraction and molecular characterization of infectious bursal disease virus.

PubMed

Purvis, Linda B; Villegas, Pedro; Perozo, Francisco

2006-12-01

Infectious bursal disease virus (IBDV) is an important poultry pathogen and is distributed world wide that can cause immune suppression and lesions of the bursa of Fabricius. The main component of the virus, VP2, is not only responsible for the bird's immune response, but is important for the molecular identification of this virus as well. The nucleic acid of the virus must be adequately preserved to be analyzed by reverse-transcriptase PCR (RT-PCR) and sequenced for the molecular characterization of the field strain. Phenol inactivation has been the standard for IBDV tissue collection and international shipment; however, there have been some reports of interference with molecular detection capabilities when using phenol. Phenol is also a hazardous chemical and must be handled and shipped carefully. The ability to use the Flinders Technology Associates filter paper (FTA card) for inactivation of several avian pathogens has been proven previously, however no work has been published on its use in IBDV nucleic acid detection. Bursas from experimentally infected birds was imprinted on FTA cards, and then placed in phenol. Samples were evaluated and compared based on molecular detection capabilities between the two inactivation methods. The nucleic acid of the virus was detected in 85% of the FTA card inactivated samples compared to 71% in the phenol inactivated samples. Sequence analysis was performed on samples inactivated by both methods and no differences were found. When comparing the RNA stability at different temperatures, euthanized IBDV infected birds were held at two different temperatures before sampling. No differences were detected for FTA sampling; however, for tissues in phenol the nucleic acid was only detectable up to 2 h post-mortem in the tissues held at 4 degrees C prior to sampling. These findings indicate that the FTA card is an efficient and reliable alternative collection method for molecular detection and characterization of IBDV.

Effective Thermal Inactivation of the Spores of Bacillus cereus Biofilms Using Microwave.

PubMed

Park, Hyong Seok; Yang, Jungwoo; Choi, Hee Jung; Kim, Kyoung Heon

2017-07-28

Microwave sterilization was performed to inactivate the spores of biofilms of Bacillus cereus involved in foodborne illness. The sterilization conditions, such as the amount of water and the operating temperature and treatment time, were optimized using statistical analysis based on 15 runs of experimental results designed by the Box-Behnken method. Statistical analysis showed that the optimal conditions for the inactivation of B. cereus biofilms were 14 ml of water, 108°C of temperature, and 15 min of treatment time. Interestingly, response surface plots showed that the amount of water is the most important factor for microwave sterilization under the present conditions. Complete inactivation by microwaves was achieved in 5 min, and the inactivation efficiency by microwave was obviously higher than that by conventional steam autoclave. Finally, confocal laser scanning microscopy images showed that the principal effect of microwave treatment was cell membrane disruption. Thus, this study can contribute to the development of a process to control food-associated pathogens.

A Planar Source of Atmospheric-Pressure Plasma Jet

NASA Astrophysics Data System (ADS)

Zhdanova, O. S.; Kuznetsov, V. S.; Panarin, V. A.; Skakun, V. S.; Sosnin, E. A.; Tarasenko, V. F.

2018-01-01

In a single-barrier discharge with voltage sharpening and low gas consumption (up to 1 L/min), plane atmospheric pressure plasma jets with a width of up to 3 cm and length of up to 4 cm in air are formed in the slit geometry of the discharge zone. The energy, temperature, and spectral characteristics of the obtained jets have been measured. The radiation spectrum contains intense maxima corresponding to vibrational transitions of the second positive system of molecular nitrogen N2 ( C 3Π u → B 3Π g ) and comparatively weak transition lines of the first positive system of the N 2 + ion ( B 2Σ u + → X 2Σ g ). By an example of inactivation of the Staphylococcus aureus culture (strain ATCC 209), it is shown that plasma is a source of chemically active particles providing the inactivation of microorganisms.

Helicases as Prospective Targets for Anti-Cancer Therapy

PubMed Central

Gupta, Rigu; Brosh, Robert M.

2008-01-01

It has been proposed that selective inactivation of a DNA repair pathway may enhance anti-cancer therapies that eliminate cancerous cells through the cytotoxic effects of DNA damaging agents or radiation. Given the unique and critically important roles of DNA helicases in the DNA damage response, DNA repair, and maintenance of genomic stability, a number of strategies currently being explored or in use to combat cancer may be either mediated or enhanced through the modulation of helicase function. The focus of this review will be to examine the roles of helicases in DNA repair that might be suitably targeted by cancer therapeutic approaches. Treatment of cancers with anti-cancer drugs such as small molecule compounds that modulate helicase expression or function is a viable approach to selectively kill cancer cells through the inactivation of helicase-dependent DNA repair pathways, particularly those associated with DNA recombination, replication restart, and cell cycle checkpoint. PMID:18473724

Application of the microbiological method DEFT/APC to detect minimally processed vegetables treated with gamma radiation

NASA Astrophysics Data System (ADS)

Araújo, M. M.; Duarte, R. C.; Silva, P. V.; Marchioni, E.; Villavicencio, A. L. C. H.

2009-07-01

Marketing of minimally processed vegetables (MPV) are gaining impetus due to its convenience, freshness and apparent health effect. However, minimal processing does not reduce pathogenic microorganisms to safe levels. Food irradiation is used to extend the shelf life and to inactivate food-borne pathogens. In combination with minimal processing it could improve safety and quality of MPV. A microbiological screening method based on the use of direct epifluorescent filter technique (DEFT) and aerobic plate count (APC) has been established for the detection of irradiated foodstuffs. The aim of this study was to evaluate the applicability of this technique in detecting MPV irradiation. Samples from retail markets were irradiated with 0.5 and 1.0 kGy using a 60Co facility. In general, with a dose increment, DEFT counts remained similar independent of the irradiation while APC counts decreased gradually. The difference of the two counts gradually increased with dose increment in all samples. It could be suggested that a DEFT/APC difference over 2.0 log would be a criteria to judge if a MPV was treated by irradiation. The DEFT/APC method could be used satisfactorily as a screening method for indicating irradiation processing.

Loss of cellular transformation efficiency induced by DNA irradiation with low-energy (10 eV) electrons.

PubMed

Kouass Sahbani, Saloua; Sanche, Leon; Cloutier, Pierre; Bass, Andrew D; Hunting, Darel J

2014-11-20

Low energy electrons (LEEs) of energies less than 20 eV are generated in large quantities by ionizing radiation in biological matter. While LEEs are known to induce single (SSBs) and double strand breaks (DSBs) in DNA, their ability to inactivate cells by inducing nonreparable lethal damage has not yet been demonstrated. Here we observe the effect of LEEs on the functionality of DNA, by measuring the efficiency of transforming Escherichia coli with a [pGEM-3Zf (-)] plasmid irradiated with 10 eV electrons. Highly ordered DNA films were prepared on pyrolitic graphite by molecular self-assembly using 1,3-diaminopropane ions (Dap(2+)). The uniformity of these films permits the inactivation of approximately 50% of the plasmids compared to <10% using previous methods, which is sufficient for the subsequent determination of their functionality. Upon LEE irradiation, the fraction of functional plasmids decreased exponentially with increasing electron fluence, while LEE-induced isolated base damage, frank DSB, and non DSB-cluster damage increased linearly with fluence. While DSBs can be toxic, their levels were too low to explain the loss of plasmid functionality observed upon LEE irradiation. Similarly, non-DSB cluster damage, revealed by transforming cluster damage into DSBs by digestion with repair enzymes, also occurred relatively infrequently. The exact nature of the lethal damage remains unknown, but it is probably a form of compact cluster damage in which the lesions are too close to be revealed by purified repair enzymes. In addition, this damage is either not repaired or is misrepaired by E. coli, since it results in plasmid inactivation, when they contain an average of three lesions. Comparison with previous results from a similar experiment performed with γ-irradiated plasmids indicates that the type of clustered DNA lesions, created directly on cellular DNA by LEEs, may be more difficult to repair than those produced by other species from radiolysis.

Inactivation of Vibrio parahaemolyticus by antimicrobial photodynamic technology using methylene blue.

PubMed

Deng, Xi; Tang, Shuze; Wu, Qian; Tian, Juan; Riley, William W; Chen, Zhenqiang

2016-03-30

Vibrio parahaemolyticus is the leading causative pathogen of gastroenteritis often related to contaminated seafood. Photodynamic inactivation has been recently proposed as a strategy for killing cells and viruses. The objective of this study was to verify the bactericidal effects caused by photodynamic inactivation using methylene blue (MB) over V. parahaemolyticus via flow cytometry, agarose gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Vibrio parahaemolyticus counts were determined using the most probable number method. A scanning electron microscope and a transmission electron microscope were employed to intuitively analyze internal and external cell structure. Combination of MB and laser treatment significantly inhibited the growth of V. parahaemolyticus. The inactivation rate of V. parahaemolyticus was >99.99% and its counts were reduced by 5 log10 in the presence of 0.05 mg mL(-1) MB when illuminated with visible light (power density 200 mW cm(-2)) for 25 min. All inactivated cells showed morphological changes, leakage of cytoplasm and degradation of protein and DNA. Results from this study indicated that photodynamic technology using MB produced significant inactivation of V. parahaemolyticus mainly brought about by the degradation of protein and DNA. © 2015 Society of Chemical Industry.

Proof-of-principle that a decoy virus protects oncolytic measles virus against neutralizing antibodies

PubMed Central

Dorneburg, Carmen; Debatin, Klaus-Michael; Wei, Jiwu; Beltinger, Christian

2018-01-01

Background Attenuated oncolytic measles virus (OMV) is a promising antitumor agent in early-phase clinical trials. However, pre-existing immunity against measles might be a hurdle for OMV therapy. Methods OMV was inactivated with short-wavelength ultraviolet light (UV-C). Loss of replication and oncolytic activity of UV-inactivated OMV were confirmed by tissue culture infective dose 50 (TCID50) assay using Vero cells and by flow cytometry using Jurkat cells. An enzyme-linked immunosorbent assay was performed to verify that UV-inactivated OMV remained antigenic. Different doses of UV-inactivated OMV were pre-cultured in media supplemented with measles immune serum. The mixture was transferred to Jurkat cells and active OMV was added. Active OMV-induced death of Jurkat cells was monitored by flow cytometry. Results UV-inactivation abrogates OMV replication while maintaining its antigenicity. UV-inactivated OMV sequesters pre-existing anti-MV antibodies in Jurkat cell culture, thereby protecting active OMV from neutralization and preserving oncolytic activity. Conclusion We prove the principle that a non-replicating OMV can serve as a “decoy” for neutralizing anti-MV antibodies, thereby allowing antitumor activity of OMV. PMID:29750140

Isolated spinach ribulose-1,5-bisphosphate carboxylase/oxgenase large subunit .epsilon. n-methyltransferase and method of inactivating ribulose-1,5-bishosphatase .epsilon. n-methyltransferase activity

DOEpatents

Houtz, Robert L.

2001-01-01

The gene sequence for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) .sup..epsilon. N-methyltansferase (protein methylase III or Rubisco LSMT) from a plant which has a des(methyl) lysyl residue in the LS is disclosed. In addition, the full-length cDNA clones for Rubisco LSMT are disclosed. Transgenic plants and methods of producing same which have the Rubisco LSMT gene inserted into the DNA are also provided. Further, methods of inactivating the enzymatic activity of Rubisco LSMT are also disclosed.

Multipoint attachment to a support protects enzyme from inactivation by organic solvents: alpha-Chymotrypsin in aqueous solutions of alcohols and diols.

PubMed

Mozhaev, V V; Sergeeva, M V; Belova, A B; Khmelnitsky, Y L

1990-03-25

Inactivation of alpha-chymotrypsin in aqueous solutions of alcohols and diols proceeds both reversibly and irreversibly. Reversible loss of the specific enzyme activity results from conformational changes (unfolding) of the enzyme detected by fluorescence spectroscopy. Multipoint covalent attachment to the matrix of polyacryl-amide gel by copolymerization method stabilizes alpha-chymotrypsin from denaturation by alcohols, the stabilizing effect increasing with the number of bonds between the protein and the support. Immobilization protects the enzyme also from irreversible inactivation by organic solvents resulting from bimolecular aggregation and autolysis.

Use of solar radiation for continuous water disinfection in isolated areas.

PubMed

Fabbricino, M; d'Antonio, L

2012-01-01

This study involved investigation of solar water disinfection in continuously working treatment plants with the aim of producing safe drinking water in isolated areas. Results were obtained from experimental work carried out on a pilot plant operating in different configurations. The use of a simple device to increase solar radiation intensity (solar concentrator) was tested, with results showing that it facilitated better performance. A comparison between transparent and black-painted glass reactors was also made, showing no difference between the two casings. Further, the effect of an increase in water temperature was analysed in detail. Temperature was found to play an important role in the disinfection process, even in cases of limited solar radiation intensities, although a synergistic effect of water heating and solar radiation for effective microbial inactivation was confirmed. Reactor design is also discussed, highlighting the importance of having a plug flow to avoid zones that do not contribute to the overall effectiveness of the process.

Biomarker for Space Radiation Risk: Painting Analysis of Chromosome Aberrations Induced by Energetic Heavy Ions in Human Cells

NASA Technical Reports Server (NTRS)

Hada, Megumi; George, Kerry; Cucinotta, Francis A.; Wu, Honglu

2007-01-01

Energetic heavy ions pose a great health risk to astronauts in extended ISS and future Lunar and Mars missions. High-LET heavy ions are particularly effective in causing various biological effects, including cell inactivation, genetic mutations, cataracts and cancer induction. Most of these biological endpoints are closely related to chromosomal damage, which can be utilized as a biomarker for radiation insults. Over the years, we have studied chromosomal damage in human fibroblast, epithelia and lymphocyte cells exposed in vitro to energetic charged particles generated at several accelerator facilities in the world. We have also studied chromosome aberrations in astronaut s peripheral blood lymphocytes before and after space flight. Various fluorescence in situ hybridization painting techniques have been used to identify from only the telomere region of the chromosome to every chromosome in a human cell. We will summarize the results of the investigations, and discuss the unique radiation signatures and biomarkers for space radiation exposure.

Microbial Inactivation by Ultrasound Assisted Supercritical Fluids

NASA Astrophysics Data System (ADS)

Benedito, Jose; Ortuño, Carmen; Castillo-Zamudio, Rosa Isela; Mulet, Antonio

A method combining supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) has been developed and tested for microbial/enzyme inactivation purposes, at different process conditions for both liquid and solid matrices. In culture media, using only SC-CO2, the inactivation rate of E. coli and S. cerevisiae increased with pressure and temperature; and the total inactivation (7-8 log-cycles) was attained after 25 and 140 min of SC-CO2 (350 bar, 36 °C) treatment, respectively. Using SC-CO2+HPU, the time for the total inactivation of both microorganisms was reduced to only 1-2 min, at any condition selected. The SC-CO2+HPU inactivation of both microorganisms was slower in juices (avg. 4.9 min) than in culture media (avg. 1.5 min). In solid samples (chicken, turkey ham and dry-cured pork cured ham) treated with SC-CO2 and SC-CO2+HPU, the inactivation rate of E. coli increased with temperature. The application of HPU to the SC-CO2 treatments accelerated the inactivation rate of E. coli and that effect was more pronounced in treatments with isotonic solution surrounding the solid food samples. The application of HPU enhanced the SC-CO2 inactivation mechanisms of microorganisms, generating a vigorous agitation that facilitated the CO2 solubilization and the mass transfer process. The cavitation generated by HPU could damage the cell walls accelerating the extraction of vital constituents and the microbial death. Thus, using the combined technique, reasonable industrial processing times and mild process conditions could be used which could result into a cost reduction and lead to the minimization in the food nutritional and organoleptic changes.

aPKCζ-dependent Repression of Yap is Necessary for Functional Restoration of Irradiated Salivary Glands with IGF-1.

PubMed

Chibly, Alejandro M; Wong, Wen Yu; Pier, Maricela; Cheng, Hongqiang; Mu, Yongxin; Chen, Ju; Ghosh, Sourav; Limesand, Kirsten H

2018-04-20

Xerostomia and salivary hypofunction often result as a consequence of radiation therapy for head and neck cancers, which are diagnosed in roughly 60,000 individuals every year in the U.S. Due to the lack of effective treatments for radiation-induced salivary hypofunction, stem cell-based therapies have been suggested to regenerate the irradiated salivary glands. Pharmacologically, restoration of salivary gland function has been accomplished in mice by administering IGF-1 shortly after radiation treatment, but it is not known if salivary stem and progenitor cells play a role. We show that radiation inactivates aPKCζ and promotes nuclear redistribution of Yap in a population of label-retaining cells in the acinar compartment of the parotid gland (PG)- which comprises a heterogeneous pool of salivary progenitors. Administration of IGF-1 post-radiation maintains activation of aPKCζ and partially rescues Yap's cellular localization in label retaining cells, while restoring salivary function. Finally, IGF-1 fails to restore saliva production in mice lacking aPKCζ, demonstrating the importance of the kinase as a potential therapeutic target.

Comparison of Humoral and Cellular Immune Responses to Inactivated Swine Influenza Virus Vaccine in Weaned Pigs

USDA-ARS?s Scientific Manuscript database

Purpose: To evaluate and compare humoral and cellular immune responses to inactivated swine influenza virus (SIV) vaccine. Methods: Fifty 3-week-old weaned pigs from a herd free of SIV and PRRSV were randomly divided into the non-vaccinated control group and vaccinated group containing 25 pigs each....

Inactivation Methods of Trypsin Inhibitor in Legumes: A Review.

PubMed

Avilés-Gaxiola, Sara; Chuck-Hernández, Cristina; Serna Saldívar, Sergio O

2018-01-01

Seed legumes have played a major role as a crop worldwide, being cultivated on about 12% to 15% of Earth's arable land; nevertheless, their use is limited by, among other things, the presence of several antinutritional factors (ANFs - naturally occurring metabolites that the plant produces to protect itself from pest attacks.) Trypsin inhibitors (TIs) are one of the most relevant ANFs because they reduce digestion and absorption of dietary proteins. Several methods have been developed in order to inactivate TIs, and of these, thermal treatments are the most commonly used. They cause loss of nutrients, affect functional properties, and require high amounts of energy. Given the above, new processes have emerged to improve the nutritional quality of legumes while trying to solve the problems caused by the use of thermal treatments. This review examines and discusses the methods developed by researchers to inactivate TI present in legumes and their effects over nutritional and functional properties. © 2017 Institute of Food Technologists®.

A cell cycle-independent, conditional gene inactivation strategy for differentially tagging wild-type and mutant cells.

PubMed

Nagarkar-Jaiswal, Sonal; Manivannan, Sathiya N; Zuo, Zhongyuan; Bellen, Hugo J

2017-05-31

Here, we describe a novel method based on intronic MiMIC insertions described in Nagarkar-Jaiswal et al. (2015) to perform conditional gene inactivation in Drosophila . Mosaic analysis in Drosophila cannot be easily performed in post-mitotic cells. We therefore, therefore, developed Flip-Flop, a flippase -dependent in vivo cassette-inversion method that marks wild-type cells with the endogenous EGFP-tagged protein, whereas mutant cells are marked with mCherry upon inversion. We document the ease and usefulness of this strategy in differential tagging of wild-type and mutant cells in mosaics. We use this approach to phenotypically characterize the loss of SNF4Aγ , encoding the γ subunit of the AMP Kinase complex. The Flip-Flop method is efficient and reliable, and permits conditional gene inactivation based on both spatial and temporal cues, in a cell cycle-, and developmental stage-independent fashion, creating a platform for systematic screens of gene function in developing and adult flies with unprecedented detail.

Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

PubMed Central

Kim, Soo-Ji; Kim, Do-Kyun

2015-01-01

UVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes were irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm2, respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm2, and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm2. Our results showed that inactivation rates after UV-LED treatment were significantly different (P < 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P < 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm2 for all three pathogens, with negligible generation of injured cells. PMID:26386061

A unified partial likelihood approach for X-chromosome association on time-to-event outcomes.

PubMed

Xu, Wei; Hao, Meiling

2018-02-01

The expression of X-chromosome undergoes three possible biological processes: X-chromosome inactivation (XCI), escape of the X-chromosome inactivation (XCI-E), and skewed X-chromosome inactivation (XCI-S). Although these expressions are included in various predesigned genetic variation chip platforms, the X-chromosome has generally been excluded from the majority of genome-wide association studies analyses; this is most likely due to the lack of a standardized method in handling X-chromosomal genotype data. To analyze the X-linked genetic association for time-to-event outcomes with the actual process unknown, we propose a unified approach of maximizing the partial likelihood over all of the potential biological processes. The proposed method can be used to infer the true biological process and derive unbiased estimates of the genetic association parameters. A partial likelihood ratio test statistic that has been proved asymptotically chi-square distributed can be used to assess the X-chromosome genetic association. Furthermore, if the X-chromosome expression pertains to the XCI-S process, we can infer the correct skewed direction and magnitude of inactivation, which can elucidate significant findings regarding the genetic mechanism. A population-level model and a more general subject-level model have been developed to model the XCI-S process. Finite sample performance of this novel method is examined via extensive simulation studies. An application is illustrated with implementation of the method on a cancer genetic study with survival outcome. © 2017 WILEY PERIODICALS, INC.

Complete inactivation of HIV-1 using photo-labeled non-nucleoside reverse transcriptase inhibitors.

PubMed

Rios, Adan; Quesada, Jorge; Anderson, Dallas; Goldstein, Allan; Fossum, Theresa; Colby-Germinario, Susan; Wainberg, Mark A

2011-01-01

We demonstrate that a photo-labeled derivative of the non-nucleoside reverse transcriptase inhibitor (NNRTI) dapivirine termed DAPY, when used together with exposure to ultraviolet light, was able to completely and irreversibly inactivate both HIV-1 RT activity as well as infectiousness in each of a T cell line and peripheral blood mononuclear cells. Control experiments using various concentrations of DAPY revealed that a combination of exposure to ultraviolet light together with use of the specific, high affinity photo-labeled compound was necessary for complete inactivation to occur. This method of HIV RT inactivation may have applicability toward preservation of an intact viral structure and warrants further investigation in regard to the potential of this approach to elicit a durable, broad protective immune response. Copyright © 2010 Elsevier B.V. All rights reserved.

Radiation sensitivity of poliovirus, a model for norovirus, inoculated in oyster ( Crassostrea gigas) and culture broth under different conditions

NASA Astrophysics Data System (ADS)

Jung, Pil-Mun; Park, Jae Seok; Park, Jin-Gyu; Park, Jae-Nam; Han, In-Jun; Song, Beom-Seok; Choi, Jong-il; Kim, Jae-Hun; Byun, Myung-Woo; Baek, Min; Chung, Young-Jin; Lee, Ju-Woon

2009-07-01

Poliovirus is a recognized surrogate for norovirus, pathogen in water and food, due to the structural and genetic similarity. Although radiation sensitivity of poliovirus in water or media had been reported, there has been no research in food model such as shellfish. In this study, oyster ( Crassostrea gigas) was incubated in artificial seawater contaminated with poliovirus, and thus radiation sensitivity of poliovirus was determined in inoculated oyster. The effects of ionizing radiation on the sensitivity of poliovirus were also evaluated under different conditions such as pH (4-7) and salt concentration (1-15%) in culture broth, and temperature during irradiation. The D10 value of poliovirus in PBS buffer, virus culture broth and oyster was determined to 0.46, 2.84 and 2.94 kGy, respectively. The initial plaque forming unit (PFU) of poliovirus in culture broth was slightly decreased as the decrease of pH and the increase of salt concentration, but radiation sensitivity was not affected by pH and salt contents. However, radiation resistance of poliovirus was increased at frozen state. These results provide the basic information for the inactivation of pathogenic virus in foods by using irradiation.

A novel multitarget model of radiation-induced cell killing based on the Gaussian distribution.

PubMed

Zhao, Lei; Mi, Dong; Sun, Yeqing

2017-05-07

The multitarget version of the traditional target theory based on the Poisson distribution is still used to describe the dose-survival curves of cells after ionizing radiation in radiobiology and radiotherapy. However, noting that the usual ionizing radiation damage is the result of two sequential stochastic processes, the probability distribution of the damage number per cell should follow a compound Poisson distribution, like e.g. Neyman's distribution of type A (N. A.). In consideration of that the Gaussian distribution can be considered as the approximation of the N. A. in the case of high flux, a multitarget model based on the Gaussian distribution is proposed to describe the cell inactivation effects in low linear energy transfer (LET) radiation with high dose-rate. Theoretical analysis and experimental data fitting indicate that the present theory is superior to the traditional multitarget model and similar to the Linear - Quadratic (LQ) model in describing the biological effects of low-LET radiation with high dose-rate, and the parameter ratio in the present model can be used as an alternative indicator to reflect the radiation damage and radiosensitivity of the cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inactivation of Mycobacterium paratuberculosis and Mycobacterium tuberculosis in fresh soft cheese by gamma radiation

NASA Astrophysics Data System (ADS)

Badr, Hesham M.

2011-11-01

The effectiveness of gamma irradiation on the inactivation of Mycobacterium paratuberculosis, Mycobacterium bovis and Mycobacterium tuberculosis in fresh soft cheese that prepared from artificially inoculated milk samples was studied. Irradiation at dose of 2 kGy was sufficient for the complete inactivation of these mycobacteria as they were not detected in the treated samples during storage at 4±1 °C for 15 days. Moreover, irradiation of cheese samples, that were prepared from un-inoculated milk, at this effective dose had no significant effects on their gross composition and contents from riboflavin, niacin and pantothenic acid, while significant decreases in vitamin A and thiamin were observed. In addition, irradiation of cheese samples had no significant effects on their pH and nitrogen fractions contents, except for the contents of ammonia, which showed a slight, but significant, increases due to irradiation. The analysis of cheese fats indicated that irradiation treatment induced significant increase in their oxidation parameters and contents from free fatty acids; however, the observed increases were relatively low. On the other hand, irradiation of cheese samples induced no significant alterations on their sensory properties. Thus, irradiation dose of 2 kGy can be effectively applied to ensure the safety of soft cheese with regards to these harmful mycobacteria.

Low pH inactivation for xenotropic gamma retrovirus in recombinant human TNF-α receptor immunoglobulin G and mechanism of inactivation.

PubMed

Ma, Rong; Cui, Xiaolan

2014-01-01

CHO-derived recombinant proteins for human therapeutic are used commonly. There are noninfectious endogenous retroviruses in CHO cells. Validation study for inactivation process is required. Murine xenotropic gamma retrovirus (X-MulV) is a model virus in validation study. In our previous study, optimum conditions for X-MulV inactivation were sifted. In this study, we performed a further research on low pH inactivation for evaluation of X-MulV clearance in manufacturing of recombinant human TNF-α receptor immunoglobulin G fusion proteins (rhTNF-α) for injection. Cell-based infectivity assay was used for the evaluation of X-MulV clearance. RhTNF-α were spiked with X-MulV and were inactivated at pH 3.60 ∼ 3.90, 25 ± 2 °C, and 0 ∼ 240 min, respectively. Samples incubated at the conditions for 15 ∼ 180 min were not inactivated effectively. For 4 h incubation, log10 reductions were achieved 5.0 log10. Biological activity of rhTNF-α incubated at pH 3.60, 25 °C for 4 h, which was assayed on murine L929 fibroblasts cells, was not affected by low pH. Env gene of X-MulV, which was detected by conventional PCR method for the first time, was not detected after incubation at pH 3.60, and it may be the mechanism of low pH inactivation. Copyright © 2013. Published by Elsevier Ltd.

Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa.

PubMed

Rice, Philip S

2011-04-23

Of the eight human herpes viruses, varicella-zoster virus, which causes chickenpox and zoster, has a unique epidemiology. Primary infection is much less common in children in the tropics compared with temperate areas. This results in increased adult susceptibility causing outbreaks, for example in health-care workers migrating from tropical to temperate countries. The recent demonstration that there are different genotypes of varicella-zoster virus and their geographic segregation into tropical and temperate areas suggests a distinct, yet previously unconsidered climatic factor may be responsible for both the clinical and molecular epidemiological features of this virus infection. Unlike other human herpes viruses, varicella-zoster virus does not require intimate contact for infection to occur indicating that transmission may be interrupted by a geographically restricted climatic factor. The factor with the largest difference between tropical and temperate zones is ultra-violet radiation. This could reduce the infectiousness of chickenpox cases by inactivating virus in vesicles, before or after rupture. This would explain decreased transmissibility in the tropics and why the peak chickenpox incidence in temperate zones occurs during winter and spring, when ultra-violet radiation is at its lowest. The evolution of geographically restricted genotypes is also explained by ultra-violet radiation driving natural selection of different virus genotypes with varying degrees of resistance to inactivation, tropical genotypes being the most resistant. Consequently, temperate viruses should be more sensitive to its effects. This is supported by the observation that temperate genotypes are found in the tropics only in specific circumstances, namely where ultra-violet radiation has either been excluded or significantly reduced in intensity. The hypothesis is testable by exposing different virus genotypes to ultra-violet radiation and quantifying virus survival by plaque forming units or quantitative mRNA RT-PCR. The ancestral varicella-zoster virus, most probably a tropical genotype, co-migrated with man as he left Africa approximately 200,000 years ago. For this virus to have lost the selective advantage of resistance to ultra-violet radiation, the hypothesis would predict that the temperate, ultra-violet sensitive virus should have acquired another selective advantage as an evolutionary trade-off. One obvious advantage could be an increased reactivation rate as zoster to set up more rounds of chickenpox transmission. If this were so, the mechanism responsible for resistance to ultra-violet radiation might also be involved in reactivation and latency. This could then provide the first insight into a genetic correlate of the survival strategy of this virus.

Selective effect of irradiation on responses to thymus-independent antigen.

PubMed

Lee, S K; Woodland, R T

1985-02-01

Low doses of ionizing radiation have a selective immunosuppressive effect on in vivo B cell responses to thymus-independent (TI) antigens. The B cell response, assayed as direct anti-trinitrophenyl (TNP)-specific plaque-forming cells (PFC), induced by type 2, TI antigens (TNP-Ficoll or TNP-Dextran), was reduced, on the average, by 10-fold in animals exposed to 200 rad of ionizing radiation 24 hr before antigen challenge. In contrast, PFC responses to type 1, TI antigens (TNP-lipopolysaccharide or TNP-Brucella abortus) are unaffected in mice exposed to the same dose of radiation. Adoptive transfers showed that this selective immunosuppression is a result of the specific inactivation of the B cell subpopulation responding to type 2, TI antigens. These experiments suggest that physiologic differences exist in the B cell subpopulations of normal mice which respond to type 1, or type 2, TI antigens.

Synergistic effect of solar radiation and solar heating to disinfect drinking water sources.

PubMed

Rijal, G K; Fujioka, R S

2001-01-01

Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol*Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60 degrees C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of < 1 CFU/100 mL within 2-5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of < 1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < F RNA virus < enterococci < E. coli < faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with solar heating of the water to disinfect the water. Thus, effective disinfection was observed even when the water temperature did not reach 60 degrees C. Finally, the hydrogen sulphide test is a simple and reliable test that householders can use to determine whether their water had been sufficiently disinfected.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

NASA Technical Reports Server (NTRS)

Campbell, J. E.; Reyes, A. L.; Wehby, A. J.; Crawford, R. G.; Wimsatt, J. C.; Peeler, J. T.

1974-01-01

Dry heat sterilization of spacecraft was investigated by studying the production of spore crops, and thermal inactivation of the spores, and bacillus subtillus. Spore assays were made by conventional plate count methods, and survival curves for the spores are presented. The results indicate that the inherent resistance of spores from a parent cell can be maintained.

Inactivation of dinoflagellate Scripsiella trochoidea in synthetic ballast water by advanced oxidation processes.

PubMed

Yang, Zhishan; Jiang, Wenju; Zhang, Yi; Lim, T M

2015-01-01

Ship-borne ballast water contributes significantly to the transfer of non-indigenous species across aquatic environments. To reduce the risk of bio-invasion, ballast water should be treated before discharge. In this study, the efficiencies of several conventional and advanced oxidation processes were investigated for potential ballast water treatment, using a marine dinoflagellate species, Scripsiella trochoidea, as the indicator organism. A stable and consistent culture was obtained and treated by ultraviolet (UV) light, ozone (O3), hydrogen peroxide (H2O2), and their various combinations. UV apparently inactivated the cells after only 10 s of irradiation, but subsequently photo-reactivation of the cells was observed for all methods involving UV. O3 exhibited 100% inactivation efficiency after 5 min treatment, while H2O2 only achieved maximum 80% inactivation in the same duration. Combined methods, e.g. UV/O3 and UV/H2O2, were found to inhibit photo-reactivation and improve treatment efficiency to some degree, indicating the effectiveness of using combined treatment processes. The total residual oxidant (TRO) levels of the methods were determined, and the results indicated that UV and O3 generated the lowest and highest TRO, respectively. The synergic effect of combined processes on TRO generation was found to be insignificant, and thus UV/O3 was recommended as a potentially suitable treatment process for ballast water.

Virus inactivation by nucleic acid extraction reagents.

PubMed

Blow, Jamie A; Dohm, David J; Negley, Diane L; Mores, Christopher N

2004-08-01

Many assume that common methods to extract viral nucleic acids are able to render a sample non-infectious. It may be that inactivation of infectious virus is incomplete during viral nucleic acid extraction methods. Accordingly, two common viral nucleic acid extraction techniques were evaluated for the ability to inactivate high viral titer specimens. In particular, the potential for TRIzol LS Reagent (Invitrogen Corp., Carlsbad, CA) and AVL Buffer (Qiagen, Valencia, CA) were examined to render suspensions of alphaviruses, flaviviruses, filoviruses and a bunyavirus non-infectious to tissue culture assay. The dilution series for both extraction reagents consistently caused cell death through a 100-fold dilution. Except for the DEN subtype 4 positive control, all viruses had titers of at least 10(6)pfu/ml. No plaques were detected in any extraction reagent plus virus combination in this study, therefore, the extraction reagents appeared to inactivate completely each of the high-titer viruses used in this study. These results support the reliance upon either TRIzol LS Reagent or AVL Buffer to render clinical or environmental samples non-infectious, which has implications for the handling and processing of samples under austere field conditions and low level containment.

Photodynamic therapy with water-soluble phtalocyanines against bacterial biofilms in teeth root canals

NASA Astrophysics Data System (ADS)

Gergova, Raina; Georgieva, Tzvetelina; Angelov, Ivan; Mantareva, Vanya; Valkanov, Serjoga; Mitov, Ivan; Dimitrov, Slavcho

2012-06-01

The study presents the PDT with metal phthalocyanines on biofilms grown in root canals of ten representatives of the Gram-positive and the Gram-negative bacterial species and a fungus Candida albicans which cause aqute teeth infections in root canals.. The extracted human single-root teeth infected for 48 h with microorganisms in conditions to form biofilms of the above pathogens were PDT treated. The stage of biofilm formation and PDT effect of the samples of the teeth were determined by the scaning electron microscopy and with standard microbial tests. The PDT treating procedure included 10 min incubation with the respected phthalocyanine and irradiated with 660 nm Diode laser for 10 min. The most strongly antibacterial activity was achieved with zinc(II) phthalocyanine (ZnPc) against Enterococcus faecalis, Staphylococcus aureus and Moraxella catarrhalis. The other Gram-negative bacteria and Candida albicans were 10-100 times more resistant than the Gram-positive species. The Gram-negative Moraxella catarrhalis and Acinetobacter baumannii were more sensitive than the enterobacteria, but eradication of Pseudomonas aeruginosa in biofilm was insignificant. The influence of the stage of biofilm formation and the initial conditions (bacterial density, photosensitizer concentration and energy fluence of radiation) to the obtained level of inactivation of biofilms was investigated. The PDT with ZnPc photosensitizers show a powerful antimicrobial activity against the most frequent pathogens in endodontic infections and this method for inactivation of pathogens may be used with sucsses for treatment of the bacterial biofilms in the root canals.

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility.

PubMed

Khodadad, Christina L; Wong, Gregory M; James, Leandro M; Thakrar, Prital J; Lane, Michael A; Catechis, John A; Smith, David J

2017-04-01

Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 10 7 spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility. The payload spent 8 h at ∼31 km above sea level, exposing bacterial spores to the stratosphere. We found that within 120 and 240 min, spore viability was significantly reduced by 2 and 4 orders of magnitude, respectively. By 480 min, <0.001% of spores carried to the stratosphere remained viable. Our balloon flight results predict that most terrestrial bacteria would be inactivated within the first sol on Mars if contaminated spacecraft surfaces receive direct sunlight. Unfortunately, an instrument malfunction prevented the acquisition of UV light measurements during our balloon mission. To make up for the absence of radiometer data, we calculated a stratosphere UV model and conducted ground tests with a 271.1 nm UVC light source (0.5 W/m 2 ), observing a similarly rapid inactivation rate when using a lower number of contaminants (640 spores per sample). The starting concentration of spores and microconfiguration on hardware surfaces appeared to influence survivability outcomes in both experiments. With the relatively few spores that survived the stratosphere, we performed a resequencing analysis and identified three single nucleotide polymorphisms compared to unexposed controls. It is therefore plausible that bacteria enduring radiation-rich environments (e.g., Earth's upper atmosphere, interplanetary space, or the surface of Mars) may be pushed in evolutionarily consequential directions. Key Words: Planetary protection-Stratosphere-Balloon-Mars analog environment-E-MIST payload-Bacillus pumilus SAFR-032. Astrobiology 17, 337-350.

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility

NASA Astrophysics Data System (ADS)

Khodadad, Christina L.; Wong, Gregory M.; James, Leandro M.; Thakrar, Prital J.; Lane, Michael A.; Catechis, John A.; Smith, David J.

2017-04-01

Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 107 spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility. The payload spent 8 h at ˜31 km above sea level, exposing bacterial spores to the stratosphere. We found that within 120 and 240 min, spore viability was significantly reduced by 2 and 4 orders of magnitude, respectively. By 480 min, <0.001% of spores carried to the stratosphere remained viable. Our balloon flight results predict that most terrestrial bacteria would be inactivated within the first sol on Mars if contaminated spacecraft surfaces receive direct sunlight. Unfortunately, an instrument malfunction prevented the acquisition of UV light measurements during our balloon mission. To make up for the absence of radiometer data, we calculated a stratosphere UV model and conducted ground tests with a 271.1 nm UVC light source (0.5 W/m2), observing a similarly rapid inactivation rate when using a lower number of contaminants (640 spores per sample). The starting concentration of spores and microconfiguration on hardware surfaces appeared to influence survivability outcomes in both experiments. With the relatively few spores that survived the stratosphere, we performed a resequencing analysis and identified three single nucleotide polymorphisms compared to unexposed controls. It is therefore plausible that bacteria enduring radiation-rich environments (e.g., Earth's upper atmosphere, interplanetary space, or the surface of Mars) may be pushed in evolutionarily consequential directions.

Drinking water treatment with ultraviolet light for travelers -- Evaluation of a mobile lightweight system.

PubMed

Timmermann, Lisa F; Ritter, Klaus; Hillebrandt, David; Küpper, Thomas

2015-01-01

The SteriPEN(®) is a handheld device for disinfecting water with ultraviolet (UV) radiation. The manufacturer claims a reduction of at least 99.9% of bacteria, viruses, and protozoa. The present study intends to verify the general effectiveness of the device. Furthermore, the influence of bottle geometry and water movement is examined and the issue of user safety with regard to UV-C radiation is addressed. The device was applied on water containing a known number of microorganisms (Escherichia coli, Staphylococcus aureus, and the spore of Geobacillusstearothermophilus) and the survival rate was examined. Three different types of bottles commonly used among travelers served as test containers. All tests were conducted with and without agitating the water during irradiation. Furthermore, a spectral analysis was performed on the light of the device. The SteriPEN(®) reached a mean reduction of more than 99.99% of bacteria and 99.57% of the spores when applied correctly. However, the results of the trials without agitating the water only yielded a 94.98% germ reduction. The device's maximal radiation intensity lies at 254 nm which is the wavelength most efficient in inactivating bacteria. The UV-C fraction is filtered out completely by common bottle materials. However, when applied in larger containers a portion of the UV-C rays exits the water surface. If applied according to the instructions the device manages a satisfactory inactivation of bacteria. However, it bears the danger of user errors relevant to health. Therefore, education on the risks of incorrect application should be included in the travel medical consultation. Also there are still aspects that need to be subject to further independent research. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Isolated spinach ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase and method of inactivating ribulose-1,5-bisphosphatase carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase activity

DOEpatents

Houtz, Robert L.

1999-01-01

The gene sequence for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) .sup..epsilon. N-methyltransferase (protein methylase III or Rubisco LSMT) from a plant which has a des(methyl) lysyl residue in the LS is disclosed. In addition, the full-length cDNA clones for Rubisco LSMT are disclosed. Transgenic plants and methods of producing same which have the Rubisco LSMT gene inserted into the DNA are also provided. Further, methods of inactivating the enzymatic activity of Rubisco LSMT are also disclosed.

Photonic approach to the selective inactivation of viruses with a near-infrared ultrashort pulsed laser

NASA Astrophysics Data System (ADS)

Tsen, K. T.; Tsen, Shaw-Wei D.; Fu, Q.; Lindsay, S. M.; Kibler, K.; Jacobs, B.; Wu, T. C.; Li, Zhe; Yan, Hao; Cope, Stephanie; Vaiana, Sara; Kiang, Juliann G.

2010-02-01

We report a photonic approach for selective inactivation of viruses with a near-infrared ultrashort pulsed (USP) laser. We demonstrate that this method can selectively inactivate viral particles ranging from nonpathogenic viruses such as M13 bacteriophage, tobacco mosaic virus (TMV) to pathogenic viruses like human papillomavirus (HPV) and human immunodeficiency virus (HIV). At the same time sensitive materials like human Jurkat T cells, human red blood cells, and mouse dendritic cells remain unharmed. Our photonic approach could be used for the disinfection of viral pathogens in blood products and for the treatment of blood-borne viral diseases in the clinic.

High-pressure processing of apple juice: kinetics of pectin methyl esterase inactivation.

PubMed

Riahi, Esmaeil; Ramaswamy, Hosahalli S

2003-01-01

High-pressure (HP) inactivation kinetics of pectin methyl esterase (PME) in apple juice were evaluated. Commercial PME was dispensed in clarified apple juice, sealed in dual peel sterilizable plastic bags, and subjected to different high-pressure processing conditions (200-400 MPa, 0-180 min). Residual enzyme activity was determined by a titration method estimating the rate of free carboxyl group released by the enzyme acting on pectin substrate at pH 7.5 (30 degrees C). The effects of pressure level and pressure holding time on enzyme inactivation were significant (p < 0.05). PME from the microbial source was found to be more resistant (p < 0.05) to pressure inactivation than PME from the orange peel. Almost a full decimal reduction in the activity of commercial PME was achieved by HP treatment at 400 MPa for 25 min. Inactivation kinetics were evaluated on the basis of a dual effect model involving a pressure pulse effect and a first-order rate model, and the pressure sensitivity of rate constants was modeled by using the z-value concept.

A pulsed light system for the disinfection of flow through water in the presence of inorganic contaminants.

PubMed

Garvey, Mary; Rowan, Neil

2015-06-01

The use of ultraviolet (UV) light for water disinfection has become increasingly popular due to on-going issues with drinking water and public health. Pulsed UV light has proved to be an effective form of inactivating a range of pathogens including parasite species. However, there are limited data available on the use of pulsed UV light for the disinfection of flowing water in the absence or presence of inorganic contaminants commonly found in water sources. Here, we report on the inactivation of test species including Bacillus endospores following pulsed UV treatment as a flow through system. Significant levels of inactivation were obtained for both retention times tested. The presence of inorganic contaminants iron and/or manganese did affect the rate of disinfection, predominantly resulting in an increase in the levels of inactivation at certain UV doses. The findings of this study suggest that pulsed UV light may provide a method of water disinfection as it successfully inactivated bacterial cells and bacterial endospores in the absence and presence of inorganic contaminants.

Modeling Radiation Effectiveness for Inactivation of Bacillus Spores

DTIC Science & Technology

2015-09-17

are the exosporium, the spore coat, the outer membrane, the cortex, the germ cell wall, the inner membrane, and the core. These are illustrated in...small amounts of carbohydrates and lipids. The 6 coat acts as the spore’s first line of defense against some chemical infiltration such as lytic enzymes...the spore as water makes up 48-57 percent of the cortex [2]. Immediately interior to the cortex is the germ cell wall which is also a peptidoglycan

Inactivation dynamics of 222 nm krypton-chlorine excilamp irradiation on Gram-positive and Gram-negative foodborne pathogenic bacteria.

PubMed

Kang, Jun-Won; Kim, Sang-Soon; Kang, Dong-Hyun

2018-07-01

The object of this study was to elucidate the bactericidal mechanism of a 222 nm Krypton Chlorine (KrCl) excilamp compared with that of a 254 nm Low Pressure mercury (LP Hg) lamp. The KrCl excilamp had higher bactericidal capacity against Gram-positive pathogenic bacteria (Staphylococcus aureus and L. monocytogenes) and Gram-negative pathogenic bacteria (S. Typhimurium and E. coli O157:H7) than did the LP Hg lamp when cell suspensions in PBS were irradiated with each type of UV lamp. It was found out that the KrCl excilamp induced cell membrane damage as a form of depolarization. From the study of respiratory chain dehydrogenase activity and the lipid peroxidation assay, it was revealed that cell membrane damage was attributed to inactivation of enzymes related to generation of membrane potential and occurrence of lipid peroxidation. Direct absorption of UV radiation which led to photoreaction through formation of an excited state was one of the causes inducing cell damage. Additionally, generation of ROS and thus occurrence of secondary damage can be another cause. The LP Hg lamp only induced damage to DNA but not to other components such as lipids or proteins. This difference was derived from differences of UV radiation absorption by cellular materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mechanism of growth delay induced in Escherichia coli by near ultraviolet radiation.

PubMed Central

Ramabhadran, T V; Jagger, J

1976-01-01

Continuously growing cultures of E. coli B/r were irradiated with a fluence of broad-band near-ultraviolet radiation (315-405 nm) sufficient to cause extensive growth delay and complete cessation of net RNA synthesis. Chloramphenicol treatment was found to stimulate resumption of RNA synthesis, similar to that observed with chloramphenicol treatment after amino-acid starvation. E. coli strains in which amino-acid starvation does not result in cessation of RNA synthesis ("relaxed" or rel- strains) show no cessation of growth and only a slight effect on the rate of growth or of RNA synthesis. These findings show that such near-UV fluences do not inactivate the RNA synthetic machinery but affect the regulation of RNA synthesis, in a manner similat to that produced by amino-acid starvation. Such regulation is believed to be mediated through alterations in concentration of guanosine tetraphosphate (ppGpp), and our estimations of ppGpp after near-UV irradiation are consistent with such an interpretation. These data, combined with earlier published data, strongly suggest that the mechanism of near-UV-induced growth delay in E. coli involves partial inactivation of certain tRNA species, which is interpreted by the cell in a manner similar to that of amino-acid starvation, causing a rise in ppGpp levels, a shut-off of net RNA synthesis, and the induction of a growth delay. Images PMID:1108019

Optimum cooking conditions for shrimp and Atlantic salmon.

PubMed

Brookmire, Lauren; Mallikarjunan, P; Jahncke, M; Grisso, R

2013-02-01

The quality and safety of a cooked food product depends on many variables, including the cooking method and time-temperature combinations employed. The overall heating profile of the food can be useful in predicting the quality changes and microbial inactivation occurring during cooking. Mathematical modeling can be used to attain the complex heating profile of a food product during cooking. Studies were performed to monitor the product heating profile during the baking and boiling of shrimp and the baking and pan-frying of salmon. Product color, texture, moisture content, mass loss, and pressed juice were evaluated during the cooking processes as the products reached the internal temperature recommended by the FDA. Studies were also performed on the inactivation of Salmonella cocktails in shrimp and salmon. To effectively predict inactivation during cooking, the Bigelow, Fermi distribution, and Weibull distribution models were applied to the Salmonella thermal inactivation data. Minimum cooking temperatures necessary to destroy Salmonella in shrimp and salmon were determined. The heating profiles of the 2 products were modeled using the finite difference method. Temperature data directly from the modeled heating profiles were then used in the kinetic modeling of quality change and Salmonella inactivation during cooking. The optimum cooking times for a 3-log reduction of Salmonella and maintaining 95% of quality attributes are 100, 233, 159, 378, 1132, and 399 s for boiling extra jumbo shrimp, baking extra jumbo shrimp, boiling colossal shrimp, baking colossal shrimp, baking Atlantic salmon, and pan frying Atlantic Salmon, respectively. © 2013 Institute of Food Technologists®

Inactivation of Geobacillus stearothermophilus Spores by High-Pressure Carbon Dioxide Treatment

PubMed Central

Watanabe, Taisuke; Furukawa, Soichi; Hirata, Junichi; Koyama, Tetsuya; Ogihara, Hirokazu; Yamasaki, Makari

2003-01-01

High-pressure CO2 treatment has been studied as a promising method for inactivating bacterial spores. In the present study, we compared this method with other sterilization techniques, including heat and pressure treatment. Spores of Bacillus coagulans, Bacillus subtilis, Bacillus cereus, Bacillus licheniformis, and Geobacillus stearothermophilus were subjected to CO2 treatment at 30 MPa and 35°C, to high-hydrostatic-pressure treatment at 200 MPa and 65°C, or to heat treatment at 0.1 MPa and 85°C. All of the bacterial spores except the G. stearothermophilus spores were easily inactivated by the heat treatment. The highly heat- and pressure-resistant spores of G. stearothermophilus were not the most resistant to CO2 treatment. We also investigated the influence of temperature on CO2 inactivation of G. stearothermophilus. Treatment with CO2 and 30 MPa of pressure at 95°C for 120 min resulted in 5-log-order spore inactivation, whereas heat treatment at 95°C for 120 min and high-hydrostatic-pressure treatment at 30 MPa and 95°C for 120 min had little effect. The activation energy required for CO2 treatment of G. stearothermophilus spores was lower than the activation energy for heat or pressure treatment. Although heat was not necessary for inactivationby CO2 treatment of G. stearothermophilus spores, CO2 treatment at 95°C was more effective than treatment at 95°C alone. PMID:14660357

Inactivation of Geobacillus stearothermophilus spores by high-pressure carbon dioxide treatment.

PubMed

Watanabe, Taisuke; Furukawa, Soichi; Hirata, Junichi; Koyama, Tetsuya; Ogihara, Hirokazu; Yamasaki, Makari

2003-12-01

High-pressure CO2 treatment has been studied as a promising method for inactivating bacterial spores. In the present study, we compared this method with other sterilization techniques, including heat and pressure treatment. Spores of Bacillus coagulans, Bacillus subtilis, Bacillus cereus, Bacillus licheniformis, and Geobacillus stearothermophilus were subjected to CO2 treatment at 30 MPa and 35 degrees C, to high-hydrostatic-pressure treatment at 200 MPa and 65 degrees C, or to heat treatment at 0.1 MPa and 85 degrees C. All of the bacterial spores except the G. stearothermophilus spores were easily inactivated by the heat treatment. The highly heat- and pressure-resistant spores of G. stearothermophilus were not the most resistant to CO2 treatment. We also investigated the influence of temperature on CO2 inactivation of G. stearothermophilus. Treatment with CO2 and 30 MPa of pressure at 95 degrees C for 120 min resulted in 5-log-order spore inactivation, whereas heat treatment at 95 degrees C for 120 min and high-hydrostatic-pressure treatment at 30 MPa and 95 degrees C for 120 min had little effect. The activation energy required for CO2 treatment of G. stearothermophilus spores was lower than the activation energy for heat or pressure treatment. Although heat was not necessary for inactivationby CO2 treatment of G. stearothermophilus spores, CO2 treatment at 95 degrees C was more effective than treatment at 95 degrees C alone.

Acute toxicity and inactivation tests of CO2 on invertebrates in drinking water treatment systems.

PubMed

Yin, Wen-Chao; Zhang, Jin-Song; Liu, Li-Jun; Zhao, Jian-Shu; Li, Tuo

2011-01-01

In addition to the esthetic problem caused by invertebrates, researchers are recently starting to be more aware of their potential importance in terms of public health. However, the inactivation methods of invertebrates which could proliferate in drinking water treatment systems are not well developed. The objective of this study is to assess the acute toxicity and inactivation effects of CO2 on familiar invertebrates in water treatment processes. The results of this study revealed that CO2 has a definite toxicity to familiar invertebrates. The values of 24-h LC50 (median lethal concentration) were calculated for each test with six groups of invertebrates. The toxicity of CO2 was higher with increasing concentrations in solution but was lower with the increase in size of the invertebrates. Above the concentration of 1,000 mg/L for the CO2 solution, the 100% inactivation time of all the invertebrates was less than 5 s, and in 15 min, the inactivation ratio showed a gradient descent with a decline in concentration. As seen for Mesocyclops thermocyclopoides, by dosing with a sodium bicarbonate solution first and adding a dilute hydrochloric acid solution 5 min later, it is possible to obtain a satisfactory inactivation effect in the GAC (granular activated carbon) filters.

Numerical evaluation of lactoperoxidase inactivation during continuous pulsed electric field processing.

PubMed

Buckow, Roman; Semrau, Julius; Sui, Qian; Wan, Jason; Knoerzer, Kai

2012-01-01

A computational fluid dynamics (CFD) model describing the flow, electric field and temperature distribution of a laboratory-scale pulsed electric field (PEF) treatment chamber with co-field electrode configuration was developed. The predicted temperature increase was validated by means of integral temperature studies using thermocouples at the outlet of each flow cell for grape juice and salt solutions. Simulations of PEF treatments revealed intensity peaks of the electric field and laminar flow conditions in the treatment chamber causing local temperature hot spots near the chamber walls. Furthermore, thermal inactivation kinetics of lactoperoxidase (LPO) dissolved in simulated milk ultrafiltrate were determined with a glass capillary method at temperatures ranging from 65 to 80 °C. Temperature dependence of first order inactivation rate constants was accurately described by the Arrhenius equation yielding an activation energy of 597.1 kJ mol(-1). The thermal impact of different PEF processes on LPO activity was estimated by coupling the derived Arrhenius model with the CFD model and the predicted enzyme inactivation was compared to experimental measurements. Results indicated that LPO inactivation during combined PEF/thermal treatments was largely due to thermal effects, but 5-12% enzyme inactivation may be related to other electro-chemical effects occurring during PEF treatments. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

Inactivation of individual Bacillus subtilis spores in dependence on their distance to single cosmic heavy ions.

PubMed

Facius, R; Reitz, G; Schafer, M

1994-10-01

For radiobiological experiments in space, designed to investigate biological effects of the heavy ions of the cosmic radiation field, a mandatory requirement is the possibility to spatially correlate the observed biological response of individual test organisms to the passage of single heavy ions. Among several undertakings towards this goal, the BIOSTACK experiments in the Apollo missions achieved the highest precision and therefore the most detailed information on this question. Spores of Bacillus subtilis as a highly radiation resistant and microscopically small test organism yielded these quantitative results. This paper will focus on experimental and procedural details, which must be included for an interpretation and a discussion of these findings in comparison to control experiments with accelerated heavy ions.

Cross linking in the radiolysis of some enzymes and related proteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lynn, K.R.

1977-01-01

In non-covalently bound complexes of several serine proteases and of ribonuclease with DNA the enzymes were protected against the effects of ionizing radiation. No scavenging by the nucleic acids was observed. Similarly, complexing trypsin with silica protected the enzyme from radiolytic destruction. Irradiation of solutions of serine proteases required about twice the D37 dose to produce about 10% polymerization: significantly lower relative doses were effective in causing polymerization in both lima bean protease inhibitor and in the octapeptidal hormone oxytocin. Several sulfhydryl enzymes which have been examined were very efficiently inactivated by ionizing radiation. There was, at the same time,more » apparent formation of novel intra-molecular -S-S- bonds.« less

Studies of inactivation mechanism of non-enveloped icosahedral virus by a visible ultrashort pulsed laser

PubMed Central

2014-01-01

Background Low-power ultrashort pulsed (USP) lasers operating at wavelengths of 425 nm and near infrared region have been shown to effectively inactivate viruses such as human immunodeficiency virus (HIV), M13 bacteriophage, and murine cytomegalovirus (MCMV). It was shown previously that non-enveloped, helical viruses such as M13 bacteriophage, were inactivated by a USP laser through an impulsive stimulated Raman scattering (ISRS) process. Recently, enveloped virus like MCMV has been shown to be inactivated by a USP laser via protein aggregation induced by an ISRS process. However, the inactivation mechanism for a clinically important class of viruses – non-enveloped, icosahedral viruses remains unknown. Results and discussions We have ruled out the following four possible inactivation mechanisms for non-enveloped, icosahedral viruses, namely, (1) inactivation due to ultraviolet C (UVC) photons produced by non-linear optical process of the intense, fundamental laser beam at 425 nm; (2) inactivation caused by thermal heating generated by the direct laser absorption/heating of the virion; (3) inactivation resulting from a one-photon absorption process via chromophores such as porphyrin molecules, or indicator dyes, potentially producing reactive oxygen or other species; (4) inactivation by the USP lasers in which the extremely intense laser pulse produces shock wave-like vibrations upon impact with the viral particle. We present data which support that the inactivation mechanism for non-enveloped, icosahedral viruses is the impulsive stimulated Raman scattering process. Real-time PCR experiments show that, within the amplicon size of 273 bp tested, there is no damage on the genome of MNV-1 caused by the USP laser irradiation. Conclusion We conclude that our model non-enveloped virus, MNV-1, is inactivated by the ISRS process. These studies provide fundamental knowledge on photon-virus interactions on femtosecond time scales. From the analysis of the transmission electron microscope (TEM) images of viral particles before and after USP laser irradiation, the locations of weak structural links on the capsid of MNV-1 were revealed. This important information will greatly aid our understanding of the structure of non-enveloped, icosahedral viruses. We envision that this non-invasive, efficient viral eradication method will find applications in the disinfection of pharmaceuticals, biologicals and blood products in the near future. PMID:24495489

Fast Disinfection of Escherichia coli Bacteria Using Carbon Nanotubes Interaction with Microwave Radiation

PubMed Central

Al-Hakami, Samer M.; Khalil, Amjad B.; Laoui, Tahar; Atieh, Muataz Ali

2013-01-01

Water disinfection has attracted the attention of scientists worldwide due to water scarcity. The most significant challenges are determining how to achieve proper disinfection without producing harmful byproducts obtained usually using conventional chemical disinfectants and developing new point-of-use methods for the removal and inactivation of waterborne pathogens. The removal of contaminants and reuse of the treated water would provide significant reductions in cost, time, liabilities, and labour to the industry and result in improved environmental stewardship. The present study demonstrates a new approach for the removal of Escherichia coli (E. coli) from water using as-produced and modified/functionalized carbon nanotubes (CNTs) with 1-octadecanol groups (C18) under the effect of microwave irradiation. Scanning/transmission electron microscopy, thermogravimetric analysis, and FTIR spectroscopy were used to characterise the morphological/structural and thermal properties of CNTs. The 1-octadecanol (C18) functional group was attached to the surface of CNTs via Fischer esterification. The produced CNTs were tested for their efficiency in destroying the pathogenic bacteria (E. coli) in water with and without the effect of microwave radiation. A low removal rate (3–5%) of (E. coli) bacteria was obtained when CNTs alone were used, indicating that CNTs did not cause bacterial cellular death. When combined with microwave radiation, the unmodified CNTs were able to remove up to 98% of bacteria from water, while a higher removal of bacteria (up to 100%) was achieved when CNTs-C18 was used under the same conditions. PMID:23606820

Theoretical studies on the inactivation mechanism of γ-aminobutyric acid aminotransferase.

PubMed

Durak, A T; Gökcan, H; Konuklar, F A S

2011-07-21

The inactivation mechanism of γ-aminobutyric acid aminotransferase (GABA-AT) in the presence of γ-vinyl-aminobutyric acid, an anti-epilepsy drug, has been studied by means of theoretical calculations. Density functional theory methods have been applied to compare the three experimentally proposed inactivation mechanisms (Silverman et al., J. Biol. Chem., 2004, 279, 363). All the calculations were performed at the B3LYP/6-31+G(d,p) level of theory. Single point solvent calculations were carried out in water, by means of an integral equation formalism-polarizable continuum model (IEFPCM) at the B3LYP/6-31+G(d,p) level of theory. The present calculations provide an insight into the mechanistic preferences of the inactivation reaction of GABA-AT. The results also allow us to elucidate the key factors behind the mechanistic preferences. The computations also confirm the importance of explicit water molecules around the reacting center in the proton transfer steps.

Stochastic and deterministic model of microbial heat inactivation.

PubMed

Corradini, Maria G; Normand, Mark D; Peleg, Micha

2010-03-01

Microbial inactivation is described by a model based on the changing survival probabilities of individual cells or spores. It is presented in a stochastic and discrete form for small groups, and as a continuous deterministic model for larger populations. If the underlying mortality probability function remains constant throughout the treatment, the model generates first-order ("log-linear") inactivation kinetics. Otherwise, it produces survival patterns that include Weibullian ("power-law") with upward or downward concavity, tailing with a residual survival level, complete elimination, flat "shoulder" with linear or curvilinear continuation, and sigmoid curves. In both forms, the same algorithm or model equation applies to isothermal and dynamic heat treatments alike. Constructing the model does not require assuming a kinetic order or knowledge of the inactivation mechanism. The general features of its underlying mortality probability function can be deduced from the experimental survival curve's shape. Once identified, the function's coefficients, the survival parameters, can be estimated directly from the experimental survival ratios by regression. The model is testable in principle but matching the estimated mortality or inactivation probabilities with those of the actual cells or spores can be a technical challenge. The model is not intended to replace current models to calculate sterility. Its main value, apart from connecting the various inactivation patterns to underlying probabilities at the cellular level, might be in simulating the irregular survival patterns of small groups of cells and spores. In principle, it can also be used for nonthermal methods of microbial inactivation and their combination with heat.

Membrane Permeabilization in Relation to Inactivation Kinetics of Lactobacillus Species due to Pulsed Electric Fields

PubMed Central

Wouters, Patrick C.; Bos, Ad P.; Ueckert, Joerg

2001-01-01

Membrane permeabilization due to pulsed electric field (PEF) treatment of gram-positive Lactobacillus cells was investigated by using propidium iodide uptake and single-cell analysis with flow cytometry. Electric field strength, energy input, treatment time, and growth phase affected membrane permeabilization of Lactobacillus plantarum during PEF treatment. A correlation between PEF inactivation and membrane permeabilization of L. plantarum cells was demonstrated, whereas no relationship was observed between membrane permeabilization and heat inactivation. The same results were obtained with a Lactobacillus fermentum strain, but the latter organism was more PEF resistant and exhibited less membrane permeabilization, indicating that various bacteria have different responses to PEF treatment. While membrane permeabilization was the main factor involved in the mechanism of inactivation, the growth phase and the acidity of the environment also influenced inactivation. By using flow cytometry it was possible to sort cells in the L. plantarum population based on different cell sizes and shapes, and the results were confirmed by image analysis. An apparent effect of morphology on membrane permeabilization was observed, and larger cells were more easily permeabilized than smaller cells. In conclusion, our results indicate that the ability of PEF treatment to cause membrane permeabilization is an important factor in determining inactivation. This finding should have an effect on the final choice of the processing parameters used so that all microorganisms can be inactivated and, consequently, on the use of PEF treatment as an alternative method for preserving food products. PMID:11425727

An inactivated yellow fever 17DD vaccine cultivated in Vero cell cultures.

PubMed

Pereira, Renata C; Silva, Andrea N M R; Souza, Marta Cristina O; Silva, Marlon V; Neves, Patrícia P C C; Silva, Andrea A M V; Matos, Denise D C S; Herrera, Miguel A O; Yamamura, Anna M Y; Freire, Marcos S; Gaspar, Luciane P; Caride, Elena

2015-08-20

Yellow fever is an acute infectious disease caused by prototype virus of the genus Flavivirus. It is endemic in Africa and South America where it represents a serious public health problem causing epidemics of hemorrhagic fever with mortality rates ranging from 20% to 50%. There is no available antiviral therapy and vaccination is the primary method of disease control. Although the attenuated vaccines for yellow fever show safety and efficacy it became necessary to develop a new yellow fever vaccine due to the occurrence of rare serious adverse events, which include visceral and neurotropic diseases. The new inactivated vaccine should be safer and effective as the existing attenuated one. In the present study, the immunogenicity of an inactivated 17DD vaccine in C57BL/6 mice was evaluated. The yellow fever virus was produced by cultivation of Vero cells in bioreactors, inactivated with β-propiolactone, and adsorbed to aluminum hydroxide (alum). Mice were inoculated with inactivated 17DD vaccine containing alum adjuvant and followed by intracerebral challenge with 17DD virus. The results showed that animals receiving 3 doses of the inactivated vaccine (2 μg/dose) with alum adjuvant had neutralizing antibody titers above the cut-off of PRNT50 (Plaque Reduction Neutralization Test). In addition, animals immunized with inactivated vaccine showed survival rate of 100% after the challenge as well as animals immunized with commercial attenuated 17DD vaccine. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modified Carbapenem Inactivation Method for Phenotypic Detection of Carbapenemase Production among Enterobacteriaceae

PubMed Central

Simner, Patricia J.; Lonsway, David R.; Roe-Carpenter, Darcie E.; Johnson, J. Kristie; Brasso, William B.; Bobenchik, April M.; Lockett, Zabrina C.; Charnot-Katsikas, Angella; Ferraro, Mary Jane; Thomson, Richard B.; Jenkins, Stephen G.; Limbago, Brandi M.; Das, Sanchita

2017-01-01

ABSTRACT The ability of clinical microbiology laboratories to reliably detect carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is an important element of the effort to prevent and contain the spread of these pathogens and an integral part of antimicrobial stewardship. All existing methods have limitations. A new, straightforward, inexpensive, and specific phenotypic method for the detection of carbapenemase production, the carbapenem inactivation method (CIM), was recently described. Here we describe a two-stage evaluation of a modified carbapenem inactivation method (mCIM), in which tryptic soy broth was substituted for water during the inactivation step and the length of this incubation was extended. A validation study was performed in a single clinical laboratory to determine the accuracy of the mCIM, followed by a nine-laboratory study to verify the reproducibility of these results and define the zone size cutoff that best discriminated between CP-CRE and members of the family Enterobacteriaceae that do not produce carbapenemases. Bacterial isolates previously characterized through whole-genome sequencing or targeted PCR as to the presence or absence of carbapenemase genes were tested for carbapenemase production using the mCIM; isolates with Ambler class A, B, and D carbapenemases, non-CP-CRE isolates, and carbapenem-susceptible isolates were included. The sensitivity of the mCIM observed in the validation study was 99% (95% confidence interval [95% CI], 93% to 100%), and the specificity was 100% (95% CI, 82% to 100%). In the second stage of the study, the range of sensitivities observed across nine laboratories was 93% to 100%, with a mean of 97%; the range of specificities was 97% to 100%, with a mean of 99%. The mCIM was easy to perform and interpret for Enterobacteriaceae, with results in less than 24 h and excellent reproducibility across laboratories. PMID:28381609

Mechanism of Bacillus subtilis Spore Inactivation by and Resistance to Supercritical CO2 plus Peracetic Acid

PubMed Central

Setlow, Barbara; Korza, George; Blatt, Kelly M.S.; Fey, Julien P.; Setlow, Peter

2015-01-01

Aims Determine how supercritical CO2 (scCO2) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2-PAA, and if spores inactivated by scCO2-PAA are truly dead. Methods and Results Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2-PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2-PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2-PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2-PAA sensitive. Conclusions These findings suggest that scCO2-PAA inactivates spores by damaging spores’ inner membrane. The spore coat provided scCO2-PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2-PAA resistance only for dry spores. Significance and Impact of Study These results provide information on mechanisms of spore inactivation of and resistance to scCO2-PAA, an agent with increasing use in sterilization applications. PMID:26535794

Combined pressure-thermal inactivation effect on spores in lu-wei beef--a traditional Chinese meat product.

PubMed

Wang, B-S; Li, B-S; Du, J-Z; Zeng, Q-X

2015-08-01

This study investigated the inactivation effect and kinetics of Bacillus coagulans and Geobacillus stearothermophilus spores suspended in lu-wei beef by combining high pressure (500 and 600 MPa) and moderate heat (70 and 80 °C or 80 and 90 °C). During pressurization, the temperature of pressure-transmitting fluid was tested with a K-type thermocouple, and the number of surviving cells was determined by a plate count method. The pressure come-up time and corresponding inactivation of Bacillus coagulans and G. stearothermophilus spores were considered during the pressure-thermal treatment. For the two types of spores, the results showed a higher inactivation effect in phosphate buffer solution than that in lu-wei beef. Among the bacteria evaluated, G. stearothermophilus spores had a higher resistance than B. coagulans spores during the pressure-thermal processing. One linear model and two nonlinear models (i.e. the Weibull and log-logistic models) were fitted to the survivor data to obtain relevant kinetic parameters, and the performance of these models was compared. The results suggested that the survival curve of the spores could be accurately described utilizing the log-logistic model, which produced the best fit for all inactivation data. The compression heating characteristics of different pressure-transmitting fluids should be considered when using high pressure to sterilize spores, particularly while the pressure is increasing. Spores can be inactivated by combining high pressure and moderate heat. The study demonstrates the synergistic inactivation effect of moderate heat in combination with high pressure in real-life food. The use of mathematical models to predict the inactivation for spores could help the food industry further to develop optimum process conditions. © 2015 The Society for Applied Microbiology.

High-Pressure Inactivation of Rotaviruses: Role of Treatment Temperature and Strain Diversity in Virus Inactivation

PubMed Central

Araud, Elbashir; DiCaprio, Erin; Yang, Zhihong; Li, Xinhui; Lou, Fangfei; Hughes, John H.; Chen, Haiqiang

2015-01-01

Rotavirus (RV) is the major etiological agent of acute gastroenteritis in infants worldwide. Although high-pressure processing (HPP) is a popular method to inactivate enteric pathogens in food, the sensitivity of different virus strains within same species and serotype to HPP is variable. This study aimed to compare the barosensitivities of seven RV strains derived from four serotypes (serotype G1, strains Wa, Ku, and K8; serotype G2, strain S2; serotype G3, strains SA-11 and YO; and serotype G4, strain ST3) following high-pressure treatment. RV strains showed various responses to HPP based on the initial temperature and had different inactivation profiles. Ku, K8, S2, SA-11, YO, and ST3 showed enhanced inactivation at 4°C compared to 20°C. In contrast, strain Wa was not significantly impacted by the initial treatment temperature. Within serotype G1, strain Wa was significantly (P < 0.05) more resistant to HPP than strains Ku and K8. Overall, the resistance of the human RV strains to HPP at 4°C can be ranked as Wa > Ku = K8 > S2 > YO > ST3, and in terms of serotype the ranking is G1 > G2 > G3 > G4. In addition, pressure treatment of 400 MPa for 2 min was sufficient to eliminate the Wa strain, the most pressure-resistant RV, from oyster tissues. HPP disrupted virion structure but did not degrade viral protein or RNA, providing insight into the mechanism of viral inactivation by HPP. In conclusion, HPP is capable of inactivating RV at commercially acceptable pressures, and the efficacy of inactivation is strain dependent. PMID:26187961

Infective and inactivated filamentous phage as carriers for immunogenic peptides.

PubMed

Samoylova, Tatiana I; Norris, Mandy D; Samoylov, Alexandre M; Cochran, Anna M; Wolfe, Karen G; Petrenko, Valery A; Cox, Nancy R

2012-07-01

The focus of this study is on development of vaccines using filamentous phage as a delivery vector for immunogenic peptides. The use of phage as a carrier for immunogenic peptides provides significant benefits such as high immunogenicity, low production costs, and high stability of phage preparations. However, introduction of live recombinant phage into the environment might represent a potential ecological problem. This, for example, may occur when vaccines are used in oral or nasal formulations in field conditions for wild and feral animals. To address this issue, comparative studies of antigenic properties of live and inactivated (non-viable) phage were accomplished. Inactivated phage, if released, will not propagate and will degrade as any other protein. In these experiments, a model phage clone that was previously selected from a phage display library and shown to stimulate production of anti-sperm antibodies with contraceptive properties was used. Multiple methods of phage inactivation were tested, including drying, freezing, autoclaving, heating, and UV irradiation. Under studied conditions, heating at 76°C for 3h, UV irradiation, and autoclaving resulted in complete phage inactivation. Phage samples treated by heat and UV were characterized by spectrophotometry and electron microscopy. To test antigenicity, live and inactivated phage preparations were injected into mice and antibody responses assayed by ELISA. It was found that phage killed by heat causes little to no immune responses, probably due to destruction of phage particles. In contrast, UV-inactivated phage stimulated production of IgG serum antibodies at the levels comparable to live phage. Thus, vaccines formulated to include UV-inactivated filamentous phage might represent environmentally safe alternatives to live phage vaccines. Copyright © 2012 Elsevier B.V. All rights reserved.

[Evaluation on the effect of immunization and safety of live attenuated and inactivated hepatitis A vaccine in China].

PubMed

Li, Hui; Zhang, Xiao-shu; An, Jing

2013-01-01

To evaluate the safety of both domestic live attenuated and inactivated hepatitis A vaccines, and to provide reference for emergent vaccination after hepatitis A outbreaks. 493 children aged 6 - 9 with negative antibody to HAV (produced by Abbott) were randomly divided into four groups as vaccinated with domestic live attenuated hepatitis A vaccine (Group A), domestic inactivated hepatitis A vaccine (Group B), imported inactivated hepatitis A vaccine (Group C) and hepatitis B vaccine (Group D) respectively. Adverse events following the immunization were observed 30 minutes, 24, 48 and 72 hours after the vaccination, under double-blind method. The main AEFIs were: fever, local pain and scleroma but no other severe AEFIs were observed. The rates of AEFIs were 13.95% in Group A, 15.25% in group B, 16.80% in group C and 25.62% in group D, with no statistical differences between these groups (χ(2) = 6.953, P > 0.05). 2 weeks after the vaccination, the positive conversion rates of domestic live attenuated hepatitis A vaccine and domestic inactivated hepatitis A vaccine were 85.0% and 94.59% respectively. The rate of domestic inactivated hepatitis A vaccine reached 100% at 4 weeks after the vaccination. The antibody levels of HAV-IgG of Group A and B in 2, 4 and 12 weeks of vaccination and of Group C were higher than that of Group D. After 12 weeks of vaccination, the antibody level of group B became higher than it was Group C. There were no differences on safety among domestic live attenuated hepatitis A vaccine, domestic inactivated hepatitis A vaccine or imported inactivated hepatitis A vaccine under routine or emergency vaccination. All the vaccines showed satisfactory effects.

Neural network model for thermal inactivation of Salmonella Typhimurium to elimination in ground chicken: Acquisition of data by whole sample enrichment, miniature most-probable-number method

USDA-ARS?s Scientific Manuscript database

Predictive models are valuable tools for assessing food safety. Existing thermal inactivation models for Salmonella and ground chicken do not provide predictions above 71 degrees C, which is below the recommended final cooked temperature of 73.9 degrees C. They also do not predict when all Salmone...

Kinetics of Inactivation of Bacillus subtilis subsp. niger Spores and Staphylococcus albus on Paper by Chlorine Dioxide Gas in an Enclosed Space.

PubMed

Wang, Tao; Wu, Jinhui; Qi, Jiancheng; Hao, Limei; Yi, Ying; Zhang, Zongxing

2016-05-15

Bacillus subtilis subsp. niger spore and Staphylococcus albus are typical biological indicators for the inactivation of airborne pathogens. The present study characterized and compared the behaviors of B. subtilis subsp. niger spores and S. albus in regard to inactivation by chlorine dioxide (ClO2) gas under different gas concentrations and relative humidity (RH) conditions. The inactivation kinetics under different ClO2 gas concentrations (1 to 5 mg/liter) were determined by first-order and Weibull models. A new model (the Weibull-H model) was established to reveal the inactivation tendency and kinetics for ClO2 gas under different RH conditions (30 to 90%). The results showed that both the gas concentration and RH were significantly (P < 0.05) and positively correlated with the inactivation of the two chosen indicators. There was a rapid improvement in the inactivation efficiency under high RH (>70%). Compared with the first-order model, the Weibull and Weibull-H models demonstrated a better fit for the experimental data, indicating nonlinear inactivation behaviors of the vegetative bacteria and spores following exposure to ClO2 gas. The times to achieve a six-log reduction of B. subtilis subsp. niger spore and S. albus were calculated based on the established models. Clarifying the kinetics of inactivation of B. subtilis subsp. niger spores and S. albus by ClO2 gas will allow the development of ClO2 gas treatments that provide an effective disinfection method. Chlorine dioxide (ClO2) gas is a novel and effective fumigation agent with strong oxidization ability and a broad biocidal spectrum. The antimicrobial efficacy of ClO2 gas has been evaluated in many previous studies. However, there are presently no published models that can be used to describe the kinetics of inactivation of airborne pathogens by ClO2 gas under different gas concentrations and RH conditions. The first-order and Weibull (Weibull-H) models established in this study can characterize and compare the behaviors of Bacillus subtilis subsp. niger spores and Staphylococcus albus in regard to inactivation by ClO2 gas, determine the kinetics of inactivation of two chosen strains under different conditions of gas concentration and RH, and provide the calculated time to achieve a six-log reduction. These results will be useful to determine effective conditions for ClO2 gas to inactivate airborne pathogens in contaminated air and other environments and thus prevent outbreaks of airborne illness. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Kinetics of Inactivation of Bacillus subtilis subsp. niger Spores and Staphylococcus albus on Paper by Chlorine Dioxide Gas in an Enclosed Space

PubMed Central

Wang, Tao; Wu, Jinhui; Hao, Limei; Yi, Ying; Zhang, Zongxing

2016-01-01

ABSTRACT Bacillus subtilis subsp. niger spore and Staphylococcus albus are typical biological indicators for the inactivation of airborne pathogens. The present study characterized and compared the behaviors of B. subtilis subsp. niger spores and S. albus in regard to inactivation by chlorine dioxide (ClO2) gas under different gas concentrations and relative humidity (RH) conditions. The inactivation kinetics under different ClO2 gas concentrations (1 to 5 mg/liter) were determined by first-order and Weibull models. A new model (the Weibull-H model) was established to reveal the inactivation tendency and kinetics for ClO2 gas under different RH conditions (30 to 90%). The results showed that both the gas concentration and RH were significantly (P < 0.05) and positively correlated with the inactivation of the two chosen indicators. There was a rapid improvement in the inactivation efficiency under high RH (>70%). Compared with the first-order model, the Weibull and Weibull-H models demonstrated a better fit for the experimental data, indicating nonlinear inactivation behaviors of the vegetative bacteria and spores following exposure to ClO2 gas. The times to achieve a six-log reduction of B. subtilis subsp. niger spore and S. albus were calculated based on the established models. Clarifying the kinetics of inactivation of B. subtilis subsp. niger spores and S. albus by ClO2 gas will allow the development of ClO2 gas treatments that provide an effective disinfection method. IMPORTANCE Chlorine dioxide (ClO2) gas is a novel and effective fumigation agent with strong oxidization ability and a broad biocidal spectrum. The antimicrobial efficacy of ClO2 gas has been evaluated in many previous studies. However, there are presently no published models that can be used to describe the kinetics of inactivation of airborne pathogens by ClO2 gas under different gas concentrations and RH conditions. The first-order and Weibull (Weibull-H) models established in this study can characterize and compare the behaviors of Bacillus subtilis subsp. niger spores and Staphylococcus albus in regard to inactivation by ClO2 gas, determine the kinetics of inactivation of two chosen strains under different conditions of gas concentration and RH, and provide the calculated time to achieve a six-log reduction. These results will be useful to determine effective conditions for ClO2 gas to inactivate airborne pathogens in contaminated air and other environments and thus prevent outbreaks of airborne illness. PMID:26969707

Effects of simulated space radiation on immunoassay components for life-detection experiments in planetary exploration missions.

PubMed

Derveni, Mariliza; Hands, Alex; Allen, Marjorie; Sims, Mark R; Cullen, David C

2012-08-01

The Life Marker Chip (LMC) instrument is part of the proposed payload on the ESA ExoMars rover that is scheduled for launch in 2018. The LMC will use antibody-based assays to detect molecular signatures of life in samples obtained from the shallow subsurface of Mars. For the LMC antibodies, the ability to resist inactivation due to space particle radiation (both in transit and on the surface of Mars) will therefore be a prerequisite. The proton and neutron components of the mission radiation environment are those that are expected to have the dominant effect on the operation of the LMC. Modeling of the radiation environment for a mission to Mars led to the calculation of nominal mission fluences for proton and neutron radiation. Various combinations and multiples of these values were used to demonstrate the effects of radiation on antibody activity, primarily at the radiation levels envisaged for the ExoMars mission as well as at much higher levels. Five antibodies were freeze-dried in a variety of protective molecular matrices and were exposed to various radiation conditions generated at a cyclotron facility. After exposure, the antibodies' ability to bind to their respective antigens was assessed and found to be unaffected by ExoMars mission level radiation doses. These experiments indicated that the expected radiation environment of a Mars mission does not pose a significant risk to antibodies packaged in the form anticipated for the LMC instrument.

Pasteurization of fruit juices of different pH values by combined high hydrostatic pressure and carbon dioxide.

PubMed

Li, Wang; Pan, Jian; Xie, Huiming; Yang, Yi; Zhou, Dianfei; Zhu, Zhaona

2012-10-01

The inactivation of the selected vegetative bacteria Escherichia coli, Listeria innocua, and Lactobacillus plantarum by high hydrostatic pressure (HHP) in physiological saline (PS) and in four fruit juices with pHs ranging from 3.4 to 6.3, with or without dissolved CO(2), was investigated. The inactivation effect of HHP on the bacteria was greatly enhanced by dissolved CO(2). Effective inactivation (>7 log) was achieved at 250 MPa for E. coli and 350 MPa for L. innocua and L. plantarum in the presence of 0.2 M CO(2) at room temperature for 15 min in PS, with additional inactivation of more than 4 log for all three bacteria species compared with the results with HHP treatment alone. The combined inactivation by HHP and CO(2) in tomato juice of pH 4.2 and carrot juice of pH 6.3 showed minor differences compared with that in PS. By comparison, the combined effect in orange juice of pH 3.8 was considerably promoted, while the HHP inactivation was enhanced only to a limited extent. In another orange juice with a pH of 3.4, all three strains lost their pressure resistance. HHP alone completely inactivated E. coli at relatively mild pressures of 200 MPa and L. innocua and L. plantarum at 300 MPa. Observations of the survival of the bacteria in treated juices also showed that the combined treatment caused more sublethal injury, which increased further inactivation at a relatively mild pH of 4.2 during storage. The results indicated that the combined treatment of HHP with dissolved CO(2) may provide an effective method for the preservation of low- or medium-acid fruit and vegetable juices at relatively low pressures. HHP alone inactivated bacteria effectively in high-acid fruit juice.

Significance of the evolutionary α1,3-galactosyltransferase (GGTA1) gene inactivation in preventing extinction of apes and old world monkeys.

PubMed

Galili, Uri

2015-01-01

The α1,3-galactosyltransferase (α1,3GT or GGTA1) gene displays unique evolutionary characteristics. This gene appeared early in mammalian evolution and is absent in other vertebrates. The α1,3GT gene is active in marsupials, nonprimate placental mammals, lemurs (prosimians) and New World monkeys, encoding the α1,3GT enzyme that synthesizes a carbohydrate antigen called "α-gal epitope." The α-gal epitope is present in large numbers on cell membrane glycolipids and glycoproteins. The α1,3GT gene was inactivated in ancestral Old World monkeys and apes by frameshift single-base deletions forming premature stop codons. Because of this gene inactivation, humans, apes, and Old World monkeys lack α-gal epitopes and naturally produce an antibody called the "anti-Gal antibody" which binds specifically to α-gal epitopes and which is the most abundant antibody in humans. The evolutionary event that resulted in the inactivation of the α1,3GT gene in ancestral Old World primates could have been mediated by a pathogen endemic to Eurasia-Africa landmass that exerted pressure for selection of primate populations lacking the α-gal epitope. Once the α-gal epitope was eliminated, primates could produce the anti-Gal antibody, possibly as means of defense against pathogens expressing this epitope. This assumption is supported by the fossil record demonstrating an almost complete extinction of apes in the late Miocene and failure of Old World monkeys to radiate into multiple species before that period. A present outcome of this evolutionary event is the anti-Gal-mediated rejection of mammalian xenografts expressing α-gal epitopes in humans, apes, and Old World monkeys.

Stimulation of phagocytosis by sulforaphane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suganuma, Hiroyuki, E-mail: hsuganu1@jhmi.edu; Fahey, Jed W., E-mail: jfahey@jhmi.edu; Bryan, Kelley E., E-mail: kbryanm1@jhmi.edu

2011-02-04

Research highlights: {yields} Sulforaphane stimulates the phagocytosis of RAW 264.7 macrophages under conditions of serum deprivation. {yields} This effect does not require Nrf2-dependent induction of phase 2 genes. {yields} Inactivation of macrophage migration inhibitory factor (MIF) by sulforaphane may be involved in stimulation of phagocytosis by sulforaphane. -- Abstract: Sulforaphane, a major isothiocyanate derived from cruciferous vegetables, protects living systems against electrophile toxicity, oxidative stress, inflammation, and radiation. A major protective mechanism is the induction of a network of endogenous cytoprotective (phase 2) genes that are regulated by transcription factor Nrf2. To obtain a more detailed understanding of the anti-inflammatorymore » and immunomodulatory effects of sulforaphane, we evaluated its effect on the phagocytosis activity of RAW 264.7 murine macrophage-like cells by measuring the uptake of 2-{mu}m diameter polystyrene beads. Sulforaphane raised the phagocytosis activity of RAW 264.7 cells but only in the absence or presence of low concentrations (1%) of fetal bovine serum. Higher serum concentrations depressed phagocytosis and abolished its stimulation by sulforaphane. This stimulation did not depend on the induction of Nrf2-regulated genes since it occurred in peritoneal macrophages of nrf2{sup -/-} mice. Moreover, a potent triterpenoid inducer of Nrf2-dependent genes did not stimulate phagocytosis, whereas sulforaphane and another isothiocyanate (benzyl isothiocyanate) had comparable inducer potencies. It has been shown recently that sulforaphane is a potent and direct inactivator of macrophage migration inhibitory factor (MIF), an inflammatory cytokine. Moreover, the addition of recombinant MIF to RAW 264.7 cells attenuated phagocytosis, but sulforaphane-inactivated MIF did not affect phagocytosis. The inactivation of MIF may therefore be involved in the phagocytosis-enhancing activity of sulforaphane.« less

PTEN loss represses glioblastoma tumor initiating cell differentiation via inactivation of Lgl1.

PubMed

Gont, Alexander; Hanson, Jennifer E L; Lavictoire, Sylvie J; Parolin, Doris A; Daneshmand, Manijeh; Restall, Ian J; Soucie, Mathieu; Nicholas, Garth; Woulfe, John; Kassam, Amin; Da Silva, Vasco F; Lorimer, Ian A J

2013-08-01

Glioblastoma multiforme is an aggressive and incurable type of brain tumor. A subset of undifferentiated glioblastoma cells, known as glioblastoma tumor initiating cells (GTICs), has an essential role in the malignancy of this disease and also appears to mediate resistance to radiation therapy and chemotherapy. GTICs retain the ability to differentiate into cells with reduced malignant potential, but the signaling pathways controlling differentiation are not fully understood at this time. PTEN loss is a very common in glioblastoma multiforme and leads to aberrant activation of the phosphoinositide 3-kinase pathway. Increased signalling through this pathway leads to activation of multiple protein kinases, including atypical protein kinase C. In Drosophila, active atypical protein kinase C has been shown to promote the self-renewal of neuroblasts, inhibiting their differentiation along a neuronal lineage. This effect is mediated by atypical protein kinase c-mediated phosphorylation and inactivation of Lgl, a protein that was first characterized as a tumour suppressor in Drosophila. The effects of the atypical protein kinase C/Lgl pathway on the differentiation status of GTICs, and its potential link to PTEN loss, have not been assessed previously. Here we show that PTEN loss leads to the phosphorylation and inactivation of Lgl by atypical protein kinase C in glioblastoma cells. Re-expression of PTEN in GTICs promoted their differentiation along a neuronal lineage. This effect was also seen when atypical protein kinase C was knocked down using RNA interference, and when a non-phosphorylatable, constitutively active form of Lgl was expressed in GTICs. Thus PTEN loss, acting via atypical protein kinase C activation and Lgl inactivation, helps to maintain GTICs in an undifferentiated state.

On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.

PubMed

Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

2008-01-01

Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine.

Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese.

PubMed

Kim, Soo-Ji; Kim, Do-Kyun; Kang, Dong-Hyun

2016-01-01

UVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes were irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm(2), respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm(2), and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm(2). Our results showed that inactivation rates after UV-LED treatment were significantly different (P < 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P < 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm(2) for all three pathogens, with negligible generation of injured cells. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Radiation processing techniques in remediation of pollutants, and the role of the IAEA in supporting capacity building in developing countries

NASA Astrophysics Data System (ADS)

Haji-Saeid, S. Mohammad.; Sampa, M. H.; Safrany, A.; Sabharwal, S.; Ramamoorthy, N.

2012-08-01

Radiation treatment, or a combination of radiation with conventional biological-chemical-physical processes, can help in the remediation of contaminated surfaces and in combating industrial chemical effluents and air pollution. The use of ionizing radiation as a powerful tool for inactivation of microbes is a valuable option to address likely threats from biohazard contamination that could be introduced either deliberately or inadvertently into areas where the public are exposed to, as well as for treatment of volatile organic compounds and similar hazardous chemical agents is an emerging development in tackling harmful pollutants. The role of the IAEA has been crucial both in supporting the development of local capabilities as well as in fostering international cooperation due to the multidisciplinary expertise required for achieving sustainable benefits. The IAEA is implementing Coordinated Research Projects, (CRP) thematic topical reviews of issues and challenges involved, and Technical Cooperation (TC) assistance in establishing and maintaining infrastructure in the MS. This paper will give an insight into the above mentioned IAEA activities, with examples of successes achieved through CRPs, as well as challenges on the road for broader dissemination of radiation processing technology for environmental remediation.

Chemical Sensitization of Clostridium botulinum Spores to Radiation in Meat1

PubMed Central

Krabbenhoft, K. L.; Corlett, D. A.; Anderson, A. W.; Elliker, P. R.

1964-01-01

Beef ground round inoculated with 1,000,000 spores of Clostridium botulinum 33-A per gram and containing various additives was exposed to gamma radiation. Spores were inactivated in samples (irradiated at 2.0, 2.5, and 3.0 Mrad) which contained sodium nitrate (1,000 ppm) plus sodium chloride (2.5%). Similar results were obtained when sodium nitrite (200 ppm) was substituted for sodium nitrate, except that there was evidence of spore survival in 1 of 120 cans irradiated at 2.0 Mrad. Spore destruction was based upon the absence of spores and mouse-lethal toxin in meat subcultures made from cans incubated at 35 C for 120 days. Spores were not destroyed when exposed to 2.5 or 3.0 Mrad in the absence of sodium nitrate, sodium nitrite, or sodium chloride. Furthermore, the use of these chemicals individually, together with radiation, was ineffective. The additives alone in the absence of radiation also did not cause spore destruction. Radiation levels of 2.0, 2.5, and 3.0 Mrad, when used with sodium chloride at 1.5 or 2.0% and sodium nitrate at 500 ppm or sodium nitrite at 100 ppm, were ineffective. PMID:14215973

Is This the Carbapenemase Test We've Been Waiting for? A Multicenter Evaluation of the Modified Carbapenem Inactivation Method.

PubMed

Butler-Wu, Susan M; Abbott, April N

2017-08-01

A plethora of phenotypic methods exist for the detection of carbapenemases; however, clinical laboratories have struggled for years with accurate, objective phenotypic detection of carbapenemase activity in Enterobacteriaceae In this issue of the Journal of Clinical Microbiology , V. M. Pierce et al. (J Clin Microbiol 55:2321-2333, 2017, https://doi.org/10.1128/JCM.00193-17) report on a multicenter evaluation of the modified carbapenem inactivation method (mCIM). The high sensitivity, specificity, reproducibility, and ease of interpretation associated with the mCIM for Enterobacteriaceae will likely lead to its adoption by clinical laboratories. Copyright © 2017 American Society for Microbiology.

Clostridium botulinum neurotoxin type B is heat-stable in milk and not inactivated by pasteurization.

PubMed

Rasooly, Reuven; Do, Paula M

2010-12-08

Foodborne botulism is caused by the ingestion of foods containing botulinum neurotoxins (BoNTs). To study the heat stability of Clostridium botulinum neurotoxins, we needed to measure and compare the activity of botulinum neurotoxins, serotypes A and B, under various pasteurization conditions. Currently, the only accepted assay to detect active C. botulinum neurotoxin is an in vivo mouse bioassay, which raises ethical concerns with regard to the use of experimental animals. In this study, noninvasive methods were used to simultaneously detect and distinguish between active BoNT serotypes A and B in one reaction and sample. We developed an enzymatic activity assay employing internally quenched fluorogenic peptides corresponding to SNAP-25, for BoNT-A, and VAMP2, for BoNT-B, as an alternative method to the mouse bioassay. Because each peptide is labeled with different fluorophores, we were able to distinguish between these two toxins. We used this method to analyze the heat stability of BoNT-A and BoNT-B. This study reports that conventional milk pasteurization (63 °C, 30 min) inactivated BoNT serotype A; however, serotype B is heat-stable in milk and not inactivated by pasteurization. Using this activity assay, we also showed that the commonly used food processes such as acidity and pasteurization, which are known to inhibit C. botulinum growth and toxin production, are more effective in inactivating BoNT serotype A than serotype B when conventional pasteurization (63 °C, 30 min) is used.

γH2AX foci formation in the absence of DNA damage: mitotic H2AX phosphorylation is mediated by the DNA-PKcs/CHK2 pathway.

PubMed

Tu, Wen-Zhi; Li, Bing; Huang, Bo; Wang, Yu; Liu, Xiao-Dan; Guan, Hua; Zhang, Shi-Meng; Tang, Yan; Rang, Wei-Qing; Zhou, Ping-Kun

2013-11-01

Phosphorylated H2AX is considered to be a biomarker for DNA double-strand breaks (DSB), but recent evidence suggests that γH2AX does not always indicate the presence of DSB. Here we demonstrate the bimodal dynamic of H2AX phosphorylation induced by ionizing radiation, with the second peak appearing when G2/M arrest is induced. An increased level of γH2AX occurred in mitotic cells, and this increase was attenuated by DNA-PKcs inactivation or Chk2 depletion, but not by ATM inhibition. The phosphorylation-mimic CHK2-T68D abrogated the attenuation of mitotic γH2AX induced by DNA-PKcs inactivation. Thus, the DNA-PKcs/CHK2 pathway mediates the mitotic phosphorylation of H2AX in the absence of DNA damage. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

PubMed Central

Harding, Alexander S.; Schwab, Kellogg J.

2012-01-01

We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Slurry and 5.6 logs by SODIS + Lime Juice in 30-minute solar exposures, compared with a 1.5 log reduction with SODIS alone (N = 3; P < 0.001). MS2 was inactivated > 3.9 logs by SODIS + Lime Slurry, 1.9 logs by SODIS + Lime Juice, and 1.4 logs by SODIS in 2.5-hour solar exposures (N = 3; P < 0.05). MNV was resistant to SODIS, with < 2 log reductions after 6 hours. Efficacy of SODIS against human norovirus should be investigated further. PMID:22492137

Reactive oxygen species in plasma against E. coli cells survival rate

NASA Astrophysics Data System (ADS)

Zhou, Ren-Wu; Zhang, Xian-Hui; Zong, Zi-Chao; Li, Jun-Xiong; Yang, Zhou-Bin; Liu, Dong-Ping; Yang, Si-Ze

2015-08-01

In this paper, we report on the contrastive analysis of inactivation efficiency of E. coli cells in solution with different disinfection methods. Compared with the hydrogen peroxide solution and the ozone gas, the atmospheric-pressure He plasma can completely kill the E. coli cells in the shortest time. The inactivation efficiency of E. coli cells in solution can be well described by using the chemical reaction rate model. X-ray photoelectron spectroscopy (XPS) analysis shows that the C-O or C=O content of the inactivated E. coli cell surface by plasma is predominantly increased, indicating the quantity of oxygen-containing species in plasma is more than those of two other methods, and then the C-C or C-H bonds can be broken, leading to the etching of organic compounds. Analysis also indicates that plasma-generated species can play a crucial role in the inactivation process by their direct reactions or the decompositions of reactive species, such as ozone into OH radicals in water, then reacting with E. coli cells. Project supported by the Natural Science Foundation of Fujian Province, China (Grant No. 2014J01025), the National Natural Science Foundation of China (Grant No. 11275261), and the Funds from the Fujian Provincial Key Laboratory for Plasma and Magnetic Resonance, China.

Susceptibility constants of airborne bacteria to dielectric barrier discharge for antibacterial performance evaluation.

PubMed

Park, Chul Woo; Hwang, Jungho

2013-01-15

Dielectric barrier discharge (DBD) is a promising method to remove contaminant bioaerosols. The collection efficiency of a DBD reactor is an important factor for determining a reactor's removal efficiency. Without considering collection, simply defining the inactivation efficiency based on colony counting numbers for DBD as on and off may lead to overestimation of the inactivation efficiency of the DBD reactor. One-pass removal tests of bioaerosols were carried out to deduce the inactivation efficiency of the DBD reactor using both aerosol- and colony-counting methods. Our DBD reactor showed good performance for removing test bioaerosols for an applied voltage of 7.5 kV and a residence time of 0.24s, with η(CFU), η(Number), and η(Inactivation) values of 94%, 64%, and 83%, respectively. Additionally, we introduce the susceptibility constant of bioaerosols to DBD as a quantitative parameter for the performance evaluation of a DBD reactor. The modified susceptibility constant, which is the ratio of the susceptibility constant to the volume of the plasma reactor, has been successfully demonstrated for the performance evaluation of different sized DBD reactors under different DBD operating conditions. Our methodology will be used for design optimization, performance evaluation, and prediction of power consumption of DBD for industrial applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Inactivation of Leishmania donovani infantum and Trypanosoma cruzi in red cell suspensions with thiazole orange.

PubMed

Wagner, Stephen J; Skripchenko, Andrey; Salata, Jeanne; O'Sullivan, Anne Marie; Cardo, Lisa J

2008-07-01

Methods for pathogen inactivation are currently available in some European countries for treatment of plasma and platelet (PLT) components; no approved method for treatment of red cells (RBCs) or whole blood is ready for implementation. In a previous study, thiazole orange (TO), a dye commonly used to count reticulated RBCs and PLTs, exhibited potent photoactivity against human immunodeficiency virus-1 and several model viruses in RBC suspensions. The aim of this study is to further evaluate the ability of TO to inactivate pathogens by measuring its activity against the protozoa Leishmania donovani infantum and Trypanosoma cruzi. RBC suspensions were deliberately contaminated with L. donovani infantum promastigotes or T. cruzi trypomastigotes and either maintained as an untreated control, incubated with 80 mumol per L TO in the dark, or treated with TO and light. Control and treated samples were inoculated into medium and subsequently microscopically examined for growth. No growth was observed in samples treated with TO in the presence or absence of light, while matched control samples lacking TO and diluted up to 5 log consistently demonstrated Leishmania or T. cruzi growth (n = 3). TO inactivated Leishmania or T. cruzi to the limit of detection in RBC suspensions without intentional illumination.

Acute inactivation of the contralesional hemisphere for longer durations improves recovery after cortical injury.

PubMed

Mansoori, Babak K; Jean-Charles, Loyda; Touvykine, Boris; Liu, Aihua; Quessy, Stephan; Dancause, Numa

2014-04-01

A rapidly growing number of studies using inhibition of the contralesional hemisphere after stroke are reporting improvement in motor performance of the paretic hand. These studies have used different treatment onset time, duration and non-invasive methods of inhibition. Whereas these results are encouraging, several questions regarding the mechanisms of inhibition and the most effective treatment parameters are currently unanswered. In the present study, we used a rat model of cortical lesion to study the effects of GABA-mediated inactivation on motor recovery. In particular, we were interested in understanding better the effect of inactivation duration when it is initiated within hours following a cortical lesion. Cortical lesions were induced with endothelin-1 microinjections. The contralesional hemisphere was inactivated with continuous infusion of the GABA-A agonist Muscimol for 3, 7 or 14days in three different groups of animals. In a fourth group, Muscimol was infused at slower rate for 14days to provide additional insights on the relation between the effects of inactivation on the non-paretic forelimb behavior and the recovery of the paretic forelimb. In spontaneously recovered animals, the lesion caused a sustained bias to use the non-paretic forelimb and long-lasting grasping deficits with the paretic forelimb. Contralesional inactivation produced a general decrease of behavioral activity, affected the spontaneous use of the forelimbs and caused a specific reduction of the non-paretic forelimb function. The intensity and the duration of these behavioral effects varied in the different experimental groups. For the paretic forelimb, increasing inactivation duration accelerated the recovery of grasping function. Both groups with 14days of inactivation had similar recovery profiles and performed better than animals that spontaneously recovered. Whereas the plateau performance of the paretic forelimb correlated with the duration of contralesional inactivation, it was not correlated with the spontaneous use of the forelimbs or with grasping performance of the non-paretic hand. Our results support that contralesional inactivation initiated within hours after a cortical lesion can improve recovery of the paretic forelimb. In our model, increasing the duration of the inactivation improved motor outcomes but the spontaneous use and motor performance of the non-paretic forelimb had no impact on recovery of the paretic forelimb. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Parameter and observation importance in modelling virus transport in saturated porous media - Investigations in a homogenous system

USGS Publications Warehouse

Barth, Gilbert R.; Hill, M.C.

2005-01-01

This paper evaluates the importance of seven types of parameters to virus transport: hydraulic conductivity, porosity, dispersivity, sorption rate and distribution coefficient (representing physical-chemical filtration), and in-solution and adsorbed inactivation (representing virus inactivation). The first three parameters relate to subsurface transport in general while the last four, the sorption rate, distribution coefficient, and in-solution and adsorbed inactivation rates, represent the interaction of viruses with the porous medium and their ability to persist. The importance of four types of observations to estimate the virus-transport parameters are evaluated: hydraulic heads, flow, temporal moments of conservative-transport concentrations, and virus concentrations. The evaluations are conducted using one- and two-dimensional homogeneous simulations, designed from published field experiments, and recently developed sensitivity-analysis methods. Sensitivity to the transport-simulation time-step size is used to evaluate the importance of numerical solution difficulties. Results suggest that hydraulic conductivity, porosity, and sorption are most important to virus-transport predictions. Most observation types provide substantial information about hydraulic conductivity and porosity; only virus-concentration observations provide information about sorption and inactivation. The observations are not sufficient to estimate these important parameters uniquely. Even with all observation types, there is extreme parameter correlation between porosity and hydraulic conductivity and between the sorption rate and in-solution inactivation. Parameter estimation was accomplished by fixing values of porosity and in-solution inactivation.

Robustness of solvent/detergent treatment of plasma derivatives: a data collection from Plasma Protein Therapeutics Association member companies.

PubMed

Dichtelmüller, Herbert O; Biesert, Lothar; Fabbrizzi, Fabrizio; Gajardo, Rodrigo; Gröner, Albrecht; von Hoegen, Ilka; Jorquera, Juan I; Kempf, Christoph; Kreil, Thomas R; Pifat, Dominique; Osheroff, Wendy; Poelsler, Gerhard

2009-09-01

Solvent/detergent (S/D) treatment is an established virus inactivation technology that has been applied in the manufacture of medicinal products derived from human plasma for more than 20 years. Data on the inactivation of enveloped viruses by S/D treatment collected from seven Plasma Protein Therapeutics Association member companies demonstrate the robustness, reliability, and efficacy of this virus inactivation method. The results from 308 studies reflecting production conditions as well as technical variables significantly beyond the product release specification were evaluated for virus inactivation, comprising different combinations of solvent and detergent (tri(n-butyl) phosphate [TNBP]/Tween 80, TNBP/Triton X-100, TNBP/Na-cholate) and different products (Factor [F]VIII, F IX, and intravenous and intramuscular immunoglobulins). Neither product class, process temperature, protein concentration, nor pH value has a significant impact on virus inactivation. A variable that did appear to be critical was the concentration of solvent and detergent. The data presented here demonstrate the robustness of virus inactivation by S/D treatment for a broad spectrum of enveloped test viruses and process variables. Our data substantiate the fact that no transmission of viruses such as human immunodeficiency virus, hepatitis B virus, hepatitis C virus, or of other enveloped viruses was reported for licensed plasma derivatives since the introduction of S/D treatment.

Impact of cold plasma on Citrobacter freundii in apple juice: inactivation kinetics and mechanisms.

PubMed

Surowsky, Björn; Fröhling, Antje; Gottschalk, Nathalie; Schlüter, Oliver; Knorr, Dietrich

2014-03-17

Various studies have shown that cold plasma is capable of inactivating microorganisms located on a variety of food surfaces, food packaging materials and process equipment under atmospheric pressure conditions; however, less attention has been paid to the impact of cold plasma on microorganisms in liquid foodstuffs. The present study investigates cold plasma's ability to inactivate Citrobacter freundii in apple juice. Optical emission spectroscopy (OES) and temperature measurements were performed to characterise the plasma source. The plasma-related impact on microbial loads was evaluated by traditional plate count methods, while morphological changes were determined using scanning electron microscopy (SEM). Physiological property changes were obtained through flow cytometric measurements (membrane integrity, esterase activity and membrane potential). In addition, mathematical modelling was performed in order to achieve a reliable prediction of microbial inactivation and to establish the basis for possible industrial implementation. C. freundii loads in apple juice were reduced by about 5 log cycles after a plasma exposure of 480s using argon and 0.1% oxygen plus a subsequent storage time of 24h. The results indicate that a direct contact between bacterial cells and plasma is not necessary for achieving successful inactivation. The plasma-generated compounds in the liquid, such as H2O2 and most likely hydroperoxy radicals, are particularly responsible for microbial inactivation. Copyright © 2014. Published by Elsevier B.V.

Disinfection methods for spores of Bacillus atrophaeus, B. anthracis, Clostridium tetani, C. botulinum and C. difficile.

PubMed

Oie, Shigeharu; Obayashi, Akiko; Yamasaki, Hirofumi; Furukawa, Hiroyuki; Kenri, Tsuyoshi; Takahashi, Motohide; Kawamoto, Keiko; Makino, Sou-ichi

2011-01-01

To evaluate disinfection methods for environments contaminated with bioterrorism-associated microorganism (Bacillus anthracis), we performed the following experiments. First, the sporicidal effects of sodium hypochlorite on spores of five bacterial species were evaluated. Bacillus atrophaeus was the most resistant to hypochlorite, followed in order by B. anthracis, Clostridium botulinum and Clostridium tetani, and Clostridium difficile. Subsequently, using B. atrophaeus spores that were the most resistant to hypochlorite, the sporicidal effects of hypochlorite at lower pH by adding vinegar were evaluated. Hypochlorite containing vinegar had far more marked sporicidal effects than hypochlorite alone. Cleaning with 0.5% (5000 ppm) hypochlorite containing vinegar inactivated B. atrophaeus spores attached to vinyl chloride and plywood plates within 15 s, while that not containing vinegar did not inactivate spores attached to cement or plywood plates even after 1 h. Therefore, the surfaces of cement or plywood plates were covered with gauze soaked in 0.5% hypochlorite containing vinegar, and the sporicidal effects were evaluated. B. atrophaeus spores attached to plywood plates were not inactivated even after 6 h, but those attached to cement plates were inactivated within 5 min. On the other hand, covering the surfaces of plywood plates with gauze soaked in 0.3% peracetic acid and gauze soaked in 2% glutaral inactivated B. atrophaeus spores within 5 min and 6 h, respectively. These results suggest that hypochlorite containing vinegar is effective for disinfecting vinyl chloride, tile, and cement plates contaminated with B. anthracis, and peracetic acid is effective for disinfecting plywood plates contaminated with such microorganism.

[Immune response to one booster dose of inactivated hepatitis A vaccine in college students].

PubMed

Liao, Z; Feng, X W; Liu, X E; Zhou, Y S; Wen, H R; Peng, S H; Zhang, Y X; Xu, B; Zhuang, H; Chen, H Y

2017-05-10

Objective: To evaluate the safety and immunogenicity of one booster dose of inactivated hepatitis A vaccine in young adults. Methods: The subjects were selected from participants in the clinical trial of immunogenicity of inactivated and attenuated live hepatitis A vaccine in young adults. Eligible subjects were those who had received one dose of inactivated or attenuated hepatitis A vaccine, could be contacted and were sero-negative before primary vaccination. All qualified subjects were immunized with one booster dose of inactivated hepatitis A vaccine. The blood samples were collected before booster dose vaccination and 28 days after the immunization. Anti-HAV antibody titer ≥20 mIU/ml was considered to be sero-protected against hepatitis A virus. Results: The GMCs in the inactivated HAV vaccine group and attenuated live vaccine group before booster dose vaccination were 70.80 mIU/ml and 50.12 mIU/ml, respectively, and the sero-protection rates were 94.7 % and 65.0 % , respectively. After the vaccination of the booster dose, the sero-protection rates in both groups were 100.0 % , and the GMCs were 2 816.09 mIU/ml and 2 654.55 mIU/ml, respectively. Conclusion: The GMCs and sero-protection rates of anti-HAV antibody in young adults declined after three years of the primary vaccination. However, the higher GMC and sero-protection rate were observed in the inactivated vaccine group than in the attenuated live vaccine group. Significant increases of GMC levels were observed in both groups after one booster dose vaccination.

Stimulation of phagocytosis by sulforaphane.

PubMed

Suganuma, Hiroyuki; Fahey, Jed W; Bryan, Kelley E; Healy, Zachary R; Talalay, Paul

2011-02-04

Sulforaphane, a major isothiocyanate derived from cruciferous vegetables, protects living systems against electrophile toxicity, oxidative stress, inflammation, and radiation. A major protective mechanism is the induction of a network of endogenous cytoprotective (phase 2) genes that are regulated by transcription factor Nrf2. To obtain a more detailed understanding of the anti-inflammatory and immunomodulatory effects of sulforaphane, we evaluated its effect on the phagocytosis activity of RAW 264.7 murine macrophage-like cells by measuring the uptake of 2-μm diameter polystyrene beads. Sulforaphane raised the phagocytosis activity of RAW 264.7 cells but only in the absence or presence of low concentrations (1%) of fetal bovine serum. Higher serum concentrations depressed phagocytosis and abolished its stimulation by sulforaphane. This stimulation did not depend on the induction of Nrf2-regulated genes since it occurred in peritoneal macrophages of nrf2(-/-) mice. Moreover, a potent triterpenoid inducer of Nrf2-dependent genes did not stimulate phagocytosis, whereas sulforaphane and another isothiocyanate (benzyl isothiocyanate) had comparable inducer potencies. It has been shown recently that sulforaphane is a potent and direct inactivator of macrophage migration inhibitory factor (MIF), an inflammatory cytokine. Moreover, the addition of recombinant MIF to RAW 264.7 cells attenuated phagocytosis, but sulforaphane-inactivated MIF did not affect phagocytosis. The inactivation of MIF may therefore be involved in the phagocytosis-enhancing activity of sulforaphane. Copyright © 2011 Elsevier Inc. All rights reserved.

Inactivation of bacteria by a mixed argon and oxygen micro-plasma as a function of exposure time.

PubMed

Weng, Chih-Chiang; Wu, Yi-Te; Liao, Juinn-Der; Kao, Chi-Yuan; Chao, Chih-Cheng; Chang, Juu-En; Hsu, Bo-Wen

2009-04-01

A radio-frequency dielectric barrier discharge (DBD) was applied as a micro-plasma device for the inactivation of bacteria, e.g., Escherichia coli. The cultured bacteria were placed on a polydimethyl siloxane (PDMS) film and placed inside the DBD cavity. The bacteria were exposed to micro-plasmas of varying oxygen/argon ratios for different exposure times. The survival of the bacteria was measured by determining bacterial growth using optical methods. The excited oxygen species increased with the increase in the oxygen to argon ratio as measured by optical emission spectroscopy (OES), but the increase of excited oxygen species in argon micro-plasma did not enhance the inactivation of bacteria. In contrast, increases in the time the bacteria were exposed to the micro-plasma were of importance. The results show that a continuous plasma flow containing energetic and reactive species may result in electro-physical interactions with bacteria exposed to the plasma leading to their inactivation. For currently-employed DBD device, addition of 0.5% oxygen to the argon micro-plasma for an exposure time of 30 sec was optimum for the inactivation of E. coli.

Studying the Role of the Mitotic Exit Network in Cytokinesis.

PubMed

Foltman, Magdalena; Sanchez-Diaz, Alberto

2017-01-01

In budding yeast cells, cytokinesis is achieved by the successful division of the cytoplasm into two daughter cells, but the precise mechanisms of cell division and its regulation are still rather poorly understood. The Mitotic Exit Network (MEN) is the signaling cascade that is responsible for the release of Cdc14 phosphatase leading to the inactivation of the kinase activity associated to cyclin-dependent kinases (CDK), which drives exit from mitosis and a rapid and efficient cytokinesis. Mitotic CDK impairs the activation of MEN before anaphase, and activation of MEN in anaphase leads to the inactivation of CDK, which presents a challenge to determine the contribution that each pathway makes to the successful onset of cytokinesis. To determine CDK and MEN contribution to cytokinesis irrespectively of each other, here we present methods to induce cytokinesis after the inactivation of CDK activity in temperature sensitive mutants of the MEN pathway. An array of methods to monitor the cellular events associated with the successful cytokinesis is included.

Comparative sensitivity to UV-B radiation of two Bacillus thuringiensis subspecies and other Bacillus sp.

PubMed

Myasnik, M; Manasherob, R; Ben-Dov, E; Zaritsky, A; Margalith, Y; Barak, Z

2001-08-01

Susceptibility of Bacillus thuringiensis spores and toxins to the UV-B range (280--330 nm) of the solar spectrum reaching Earth's surface may be responsible for its inactivation and low persistence in nature. Spores of the mosquito larvicidal B. thuringiensis subsp. israelensis were significantly more resistant to UV-B than spores of the lepidopteran-active subsp. kurstaki. Spores of subsp. israelensis were as resistant to UV-B as spores of B. subtilis and more resistant than spores of the closely related B. cereus and another mosquito larvicidal species B. sphaericus. Sensitivity of B. thuringiensis subsp. israelensis spores to UV-B radiation depended upon their culture age; 24-h cultures, approaching maximal larvicidal activity, were still sensitive. Maximal resistance to UV-B was achieved only at 48 h.

HPLC-MS method for the quantification of nine anti-HIV drugs from dry plasma spot on glass filter and their long term stability in different conditions.

PubMed

D'Avolio, Antonio; Simiele, Marco; Siccardi, Marco; Baietto, Lorena; Sciandra, Mauro; Bonora, Stefano; Di Perri, Giovanni

2010-09-05

A bioanalytical method for the determination of most commonly prescribed protease inhibitors (saquinavir, atazanavir, amprenavir, darunavir, lopinavir and ritonavir) and non-nucleoside reverse transcriptase inhibitors (etravirine, efavirenz and nevirapine) was developed, modifying our previous HPLC-MS chromatographic run, validated and a complete short and long term stability evaluation was carried out. One hundred microlitres of plasma were distributed on a collection glass paper filter (Glass-Microfibre from Sartorius), then the filter underwent thermal treatment, both for drying and for HIV inactivation, and stored at room temperature, 4 degrees C and -20 degrees C. The analytes were extracted from the filter disc using tert-butylmethylether with basic pH, after the addition of the internal standards quinoxaline. The extract was dried, reconstituted and the chromatographic separation was performed on a reversed-phase C-18 column (150 mm x 2.0 mm) and the analytes were quantified using a single quadrupole mass spectrometer. The method was validated considering the concentration ranges encountered in clinical trials and the routine clinical practice. The assay was linear over the concentration ranges tested. Accuracies ranged from 92.1% to 111.9% and intra-day and inter-day relative standard deviation for all quality control levels ranged from 0.2 to 12.9 and 3.1 to 14.4, respectively. Analytes in dried plasma spots were stable for longer time when dried/inactivation step was carried out before storage compared to samples not dried/inactivated before the analysis. The dried/inactivation step allows shipment of samples at room temperature without any risks, therefore the developed and validated method enables an easy and cheap sample shipment for therapeutic drug monitoring and pharmacokinetic studies. 2010 Elsevier B.V. All rights reserved.

Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa

PubMed Central

2011-01-01

Background Of the eight human herpes viruses, varicella-zoster virus, which causes chickenpox and zoster, has a unique epidemiology. Primary infection is much less common in children in the tropics compared with temperate areas. This results in increased adult susceptibility causing outbreaks, for example in health-care workers migrating from tropical to temperate countries. The recent demonstration that there are different genotypes of varicella-zoster virus and their geographic segregation into tropical and temperate areas suggests a distinct, yet previously unconsidered climatic factor may be responsible for both the clinical and molecular epidemiological features of this virus infection. Presentation of the hypothesis Unlike other human herpes viruses, varicella-zoster virus does not require intimate contact for infection to occur indicating that transmission may be interrupted by a geographically restricted climatic factor. The factor with the largest difference between tropical and temperate zones is ultra-violet radiation. This could reduce the infectiousness of chickenpox cases by inactivating virus in vesicles, before or after rupture. This would explain decreased transmissibility in the tropics and why the peak chickenpox incidence in temperate zones occurs during winter and spring, when ultra-violet radiation is at its lowest. The evolution of geographically restricted genotypes is also explained by ultra-violet radiation driving natural selection of different virus genotypes with varying degrees of resistance to inactivation, tropical genotypes being the most resistant. Consequently, temperate viruses should be more sensitive to its effects. This is supported by the observation that temperate genotypes are found in the tropics only in specific circumstances, namely where ultra-violet radiation has either been excluded or significantly reduced in intensity. Testing the Hypothesis The hypothesis is testable by exposing different virus genotypes to ultra-violet radiation and quantifying virus survival by plaque forming units or quantitative mRNA RT-PCR. Implications of the hypothesis The ancestral varicella-zoster virus, most probably a tropical genotype, co-migrated with man as he left Africa approximately 200,000 years ago. For this virus to have lost the selective advantage of resistance to ultra-violet radiation, the hypothesis would predict that the temperate, ultra-violet sensitive virus should have acquired another selective advantage as an evolutionary trade-off. One obvious advantage could be an increased reactivation rate as zoster to set up more rounds of chickenpox transmission. If this were so, the mechanism responsible for resistance to ultra-violet radiation might also be involved in reactivation and latency. This could then provide the first insight into a genetic correlate of the survival strategy of this virus. PMID:21513563

Effects of UV-B radiation on photosynthesis activity of Wolffia arrhiza as probed by chlorophyll fluorescence transients

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Anken, Ralf H.; Lu, Jinying; Liu, Yongding

2010-04-01

The higher plant Wolffia arrhiza is regarded to be well suited concerning the provision of photosynthetic products in the cycle of matter of a Controlled Ecological Life Support System (CELSS) to be established in the context of extraterrestrial, human-based colonization and long-term space flight. Since UV radiation is one major extraterrestrial environmental stress for growth of any plant, effects of UV-B radiation on W. arrhiza were assessed in the present study. We found that UV-B radiation significantly inhibited photosynthetic CO2 assimilation activity, and the contents of chlorophyll a, chlorophyll b (Chl a, Chl b) and carotenoids considerably decreased when plants were exposed to UV-B radiation for 12 h. High UV-B radiation also declined the quantum yield of primary photochemistry (φpo), the quantum yield for electron transport (φEo) and the efficiency per trapped excitation (Ψo) in W. arrhiza simultaneously, while the amount of active PSII reaction centers per excited cross section (RC/CS) and the total number of active reaction centers per absorption (RC/ABS) had comparative changes. These results indicate that the effects of UV-B radiation on photosynthesis of W. arrhiza is due to an inhibition of the electron transport and via inactivation of reaction centers, but the inhibition may take place at more than one site in the photosynthetic apparatus.

Inactivation of the microbiota and effect on the quality attributes of pineapple juice using a continuous flow ultrasound-assisted supercritical carbon dioxide system.

PubMed

Paniagua-Martínez, I; Mulet, A; García-Alvarado, M A; Benedito, J

2018-01-01

Supercritical carbon dioxide inactivation technology represents a promising nonthermal processing method, as it causes minimum impact on the nutritional food properties. The aim of this study was to analyze the combined effect of supercritical carbon dioxide and high-power ultrasound on the inactivation of natural microbiota and the quality attributes of pineapple juice treated in a continuous flow system. Different juice residence times (3.06-4.6 min), at 100 bar and 31.5 ℃, were used. The results indicated that the microbiota inactivation was complete and the differences obtained in the quality attributes (2.2% for pH, 4.8% for °Brix, 2% for vitamin C) were minimal. During storage, microorganisms were not able to recover and the vitamin C decrease could be limited to 8.2% after four weeks. The results demonstrated that the supercritical carbon dioxide-high-power ultrasound technique could be an excellent alternative for the cold pasteurization of pineapple juice.

Comparison of animal infectivity, excystation, and fluorogenic dye as measures of Giardia muris cyst inactivation by ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Labatiuk, C.W.; Finch, G.R.; Belosevic, M.

1991-11-01

Giardia muris cyst viability after ozonation was compared by using fluorescein diacetate-ethidium bromide staining, the C3H/HeN mouse-G. muris model, and in vitro excystation. Bench-scale batch experiments were conducted under laboratory conditions (pH 6.7, 22C) in ozone-demand-free phosphate buffer. There was a significant difference between fluorogenic staining and infectivity with fluorogenic staining overestimating viability compared with infectivity estimates of viability. This suggests that viable cysts as indicated by fluorogenic dyes may not be able to complete the life cycle and produce an infection. No significant differences between infectivity and excystation and between fluorogenic staining and excystation were detected for inactivations upmore » to 99.9%. Only animal infectivity had the sensitivity to detect inactivations greater than 99.9%. Therefore, the animal model is the best method currently available for detecting high levels of G. muris cyst inactivation.« less

Studies on an inactivated vaccine against rabies virus in domestic animals.

PubMed

Monaco, F; Franchi, P M; Lelli, R

2006-01-01

An inactivated vaccine against rabies virus was prepared from the attenuated ATCC PV-12 viral rabbit Pasteur strain. The virus was grown on Baby Hamster Kidney (BHK21) cells, and the supernatant was purified by filtration and inactivated with beta-propriolactone. The inactivated product was checked according to the NHI and European Pharmacopoeia methods. Part of the product was then lyophilised and the other part was adjuvanted with Al(OH)3. Both parts were used to vaccinate and boost groups of horses, cattle and sheep at different intervals. Their immunogenicity was compared with a similar commercial product. Blood samples were collected on a regular basis and the antibody titre was determined by the Fluorescence Antibody Virus Neutralisation (FAVN) test. No significant differences were found between species after both inoculations even though the immune response increased in intensity and duration after the booster dose in all the animals tested and was stronger and lasted longer with the adjuvanted aliquot.

Electrochemical Detection of E. coli O157:H7 in Water after Electrocatalytic and Ultraviolet Treatments Using a Polyguanine-Labeled Secondary Bead Sensor.

PubMed

Beeman, Michael G; Nze, Ugochukwu C; Sant, Himanshu J; Malik, Hammad; Mohanty, Swomitra; Gale, Bruce K; Carlson, Krista

2018-05-10

The availability of clean drinking water is a significant problem worldwide. Many technologies exist for purifying drinking water, however, many of these methods require chemicals or use simple methods, such as boiling and filtering, which may or may not be effective in removing waterborne pathogens. Present methods for detecting pathogens in point-of-use (POU) sterilized water are typically time prohibitive or have limited ability differentiating between active and inactive cells. This work describes a rapid electrochemical sensor to differentially detect the presence of active Escherichia coli (E. coli) O157:H7 in samples that have been partially or completely sterilized using a new POU electrocatalytic water purification technology based on superradicals generated by defect laden titania (TiO₂) nanotubes. The sensor was also used to detect pathogens sterilized by UV-C radiation for a comparison of different modes of cell death. The sensor utilizes immunomagnetic bead separation to isolate active bacteria by forming a sandwich assay comprised of antibody functionalized secondary magnetic beads, E. coli O157:H7, and polyguanine (polyG) oligonucleotide functionalized secondary polystyrene beads as an electrochemical tag. The assay is formed by the attachment of antibodies to active receptors on the membrane of E. coli , allowing the sensor to differentially detect viable cells. Ultravioloet (UV)-C radiation and an electrocatalytic reactor (ER) with integrated defect-laden titania nanotubes were used to examine the sensors’ performance in detecting sterilized cells under different modes of cell death. Plate counts and flow cytometry were used to quantify disinfection efficacy and cell damage. It was found that the ER treatments shredded the bacteria into multiple fragments, while UV-C treatments inactivated the bacteria but left the cell membrane mostly intact.

Influence of anoxia on the induction of mutations by phenylalanine radicals during gamma-irradiation of plasmid DNA in aqueous solution.

PubMed

Kuipers, Gitta K; Slotman, Ben J; Reitsma-Wijker, Carola A; van Andel, Rob J; Poldervaart, Hester A; Lafleur, M Vincent M

2004-12-21

When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during gamma-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the gamma-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radicals under anoxic conditions.

Remote monitoring of chlorophyll fluorescence in two reef corals during the 2005 bleaching event at Lee Stocking Island, Bahamas

NASA Astrophysics Data System (ADS)

Manzello, D.; Warner, M.; Stabenau, E.; Hendee, J.; Lesser, M.; Jankulak, M.

2009-03-01

Zooxanthellae fluorescence was measured in situ, remotely, and in near real-time with a pulse amplitude modulated (PAM) fluorometer for a colony of Siderastrea siderea and Agaricia tenuifolia at Lee Stocking Island, Bahamas during the Caribbean-wide 2005 bleaching event. These colonies displayed evidence of photosystem II (PS II) inactivation coincident with thermal stress and seasonally high doses of solar radiation. Hurricane-associated declines in temperature and light appear to have facilitated the recovery of maximum quantum yield of PS II within these two colonies, although both corals responded differently to individual storms. PAM fluorometry, coupled with long-term measurement of in situ light and temperature, provides much more detail of coral photobiology on a seasonal time scale and during possible bleaching conditions than sporadic, subjective, and qualitative observations. S. siderea displayed evidence of PS II inactivation over a month prior to the issuing of a satellite-based, sea surface temperature (SST) bleaching alert by the National Oceanic and Atmospheric Administration (NOAA). In fact, recovery had already begun in S. siderea when the bleaching alert was issued. Fluorescence data for A. tenuifolia were difficult to interpret because the shaded parts of a colony were monitored and thus did not perfectly coincide with thermal stress and seasonally high doses of solar radiation as in S. siderea. These results further emphasize the limitations of solely monitoring SST (satellite or in situ) as a bleaching indicator without considering the physiological status of coral-zooxanthellae symbioses.

Model of radiation transmittance by inorganic fouling on UV reactor lamp sleeves.

PubMed

Wait, Isaac W; Blatchley, Ernest R

2010-11-01

The efficacy of UV disinfection of water depends on the ability of radiation to pass from UV lamps through the quartz sleeves that encase them; the accumulation of metal-containing foulants on sleeve surfaces inhibits disinfection by absorbing radiation that would otherwise be available for inactivation. In a series of experiments, the composition and quantity of sleeve foulants were studied relative to water chemistry and sleeve transmittance. Findings indicate that iron and calcium dominate fouling, with elevated fouling activity by iron, aluminum, manganese, and zinc. A regression-based modeling approach was used to characterize and quantify the effects of foulant metals on UV absorbance. The molar extinction coefficient for iron was found to be more than 3 times greater than that of calcium. Iron's relatively high activity in fouling reactions, elevated capacity to absorb UV, and reduced solubility under oxidizing conditions makes it a fouling precursor of particular concern, with respect to potential for sleeve fouling in UV reactors.

Improved Predictions of Drug-Drug Interactions Mediated by Time-Dependent Inhibition of CYP3A.

PubMed

Yadav, Jaydeep; Korzekwa, Ken; Nagar, Swati

2018-05-07

Time-dependent inactivation (TDI) of cytochrome P450s (CYPs) is a leading cause of clinical drug-drug interactions (DDIs). Current methods tend to overpredict DDIs. In this study, a numerical approach was used to model complex CYP3A TDI in human-liver microsomes. The inhibitors evaluated included troleandomycin (TAO), erythromycin (ERY), verapamil (VER), and diltiazem (DTZ) along with the primary metabolites N-demethyl erythromycin (NDE), norverapamil (NV), and N-desmethyl diltiazem (NDD). The complexities incorporated into the models included multiple-binding kinetics, quasi-irreversible inactivation, sequential metabolism, inhibitor depletion, and membrane partitioning. The resulting inactivation parameters were incorporated into static in vitro-in vivo correlation (IVIVC) models to predict clinical DDIs. For 77 clinically observed DDIs, with a hepatic-CYP3A-synthesis-rate constant of 0.000 146 min -1 , the average fold difference between the observed and predicted DDIs was 3.17 for the standard replot method and 1.45 for the numerical method. Similar results were obtained using a synthesis-rate constant of 0.000 32 min -1 . These results suggest that numerical methods can successfully model complex in vitro TDI kinetics and that the resulting DDI predictions are more accurate than those obtained with the standard replot approach.

Atomic Force Microscope Investigations of Bacterial Biofilms Treated with Gas Discharge Plasmas

NASA Astrophysics Data System (ADS)

Vandervoort, Kurt; Zelaya, Anna; Brelles-Marino, Graciela

2012-02-01

We present investigations of bacterial biofilms before and after treatment with gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve biofilm communities, where bacteria grow embedded in an exopolysaccharide matrix, and cooperative interactions between cells make organisms less susceptible to standard inactivation methods. In this study, biofilms formed by the opportunistic bacterium Pseudomonas aeruginosa were imaged before and after plasma treatment using an atomic force microscope (AFM). Through AFM images and micromechanical measurements we observed bacterial morphological damage and reduced AFM tip-sample surface adhesion following plasma treatment.

Enhancing Food Processing by Pulsed and High Voltage Electric Fields: Principles and Applications.

PubMed

Wang, Qijun; Li, Yifei; Sun, Da-Wen; Zhu, Zhiwei

2018-02-02

Improvements in living standards result in a growing demand for food with high quality attributes including freshness, nutrition and safety. However, current industrial processing methods rely on traditional thermal and chemical methods, such as sterilization and solvent extraction, which could induce negative effects on food quality and safety. The electric fields (EFs) involving pulsed electric fields (PEFs) and high voltage electric fields (HVEFs) have been studied and developed for assisting and enhancing various food processes. In this review, the principles and applications of pulsed and high voltage electric fields are described in details for a range of food processes, including microbial inactivation, component extraction, and winemaking, thawing and drying, freezing and enzymatic inactivation. Moreover, the advantages and limitations of electric field related technologies are discussed to foresee future developments in the food industry. This review demonstrates that electric field technology has a great potential to enhance food processing by supplementing or replacing the conventional methods employed in different food manufacturing processes. Successful industrial applications of electric field treatments have been achieved in some areas such as microbial inactivation and extraction. However, investigations of HVEFs are still in an early stage and translating the technology into industrial applications need further research efforts.

Inactivation of antibiotic resistance genes in municipal wastewater by chlorination, ultraviolet, and ozonation disinfection.

PubMed

Zhuang, Yao; Ren, Hongqiang; Geng, Jinju; Zhang, Yingying; Zhang, Yan; Ding, Lili; Xu, Ke

2015-05-01

This study investigated the inactivation of two antibiotic resistance genes (ARGs)-sul1 and tetG, and the integrase gene of class 1 integrons-intI1 by chlorination, ultraviolet (UV), and ozonation disinfection. Inactivation of sul1, tetG, and intI1 underwent increased doses of three disinfectors, and chlorine disinfection achieved more inactivation of ARGs and intI1 genes (chlorine dose of 160 mg/L with contact time of 120 min for 2.98-3.24 log reductions of ARGs) than UV irradiation (UV dose of 12,477 mJ/cm(2) for 2.48-2.74 log reductions of ARGs) and ozonation disinfection (ozonation dose of 177.6 mg/L for 1.68-2.55 log reductions of ARGs). The 16S rDNA was more efficiently removed than ARGs by ozone disinfection. The relative abundance of selected genes (normalized to 16S rDNA) increased during ozonation and with low doses of UV and chlorine disinfection. Inactivation of sul1 and tetG showed strong positive correlations with the inactivation of intI1 genes (for sul1, R (2)  = 0.929 with p < 0.01; for tetG, R (2)  = 0.885 with p < 0.01). Compared to other technologies (ultraviolet disinfection, ozonation disinfection, Fenton oxidation, and coagulation), chlorination is an alternative method to remove ARGs from wastewater effluents. At a chlorine dose of 40 mg/L with 60 min contact time, the selected genes inactivation efficiency could reach 1.65-2.28 log, and the cost was estimated at 0.041 yuan/m(3).

A bench-scale, cost effective and simple method to elicit Lycopersicon esculentum cv. PKM1 (tomato) plants against Cucumber mosaic virus attack using ozone-mediated inactivated Cucumber mosaic virus inoculum.

PubMed

Sudhakar, N; Nagendra-Prasad, D; Mohan, N; Murugesan, K

2007-12-01

Studies were undertaken to evaluate ozone for inactivation of Cucumber mosaic virus present in the inoculum and to stimulate Lycopersicon esculentum cv. PKM1 (tomato) plants against Cucumber mosaic virus infection by using the inactivated Cucumber mosaic virus inoculum. Application of a T(4) (0.4mg/l) concentration of ozone to the inoculum containing Cucumber mosaic virus resulted in complete inactivation of the virus. The inactivated viral inoculum was mixed with a penetrator (delivery agent), referred to as T(4) preparation, and it was evaluated for the development of systemic acquired resistance in the tomato plants. Application of a T(4) preparation 5 days before inoculation with the Cucumber mosaic virus protected tomato plants from the effects of Cucumber mosaic virus. Among the components of the inactivated virus tested, coat protein subunits and aggregates were responsible for the acquired resistance in tomato plants. In field trials, the results of enzyme-linked immunosorbent assay revealed that, Cucumber mosaic virus accumulation was significantly less for all the test plants (16%) sprayed with the T(4) preparation than untreated control plants (89.5%) at 28 days postinoculation (dpi). A remarkable increase in the activities of the total soluble phenolics (10-fold) and salicylic acid (16-fold) was detected 5 days after the treatment in foliar extracts of test plants relative to untreated control plants. The results showed that treatment of tomato plants with inactivated viral inoculum led to a significant enhancement of protection against Cucumber mosaic virus attack in a manner that mimics a real pathogen and induces systemic acquired resistance.

Mechanism of virus inactivation by cold atmospheric-pressure plasma and plasma-activated water.

PubMed

Guo, Li; Xu, Ruobing; Gou, Lu; Liu, Zhichao; Zhao, Yiming; Liu, Dingxin; Zhang, Lei; Chen, Hailan; Kong, Michael G

2018-06-18

Viruses are serious pathogenic contamination that severely affect the environment and human health. Cold atmospheric-pressure plasma efficiently inactivates pathogenic bacteria, however, the mechanism of virus inactivation by plasma is not fully understood. In this study, surface plasma in argon mixed with 1% air and plasma-activated water were used to treat water containing bacteriophages. Both agents efficiently inactivated bacteriophages T4, Φ174, and MS2 in a time-dependent manner. Prolonged storage had marginal effects on the anti-viral activity of plasma-activated water. DNA and protein analysis revealed that the reactive species generated by plasma damaged both nucleic acid and proteins, in consistent with the morphological examination showing that plasma treatment caused the aggregation of bacteriophages. The inactivation of bacteriophages was alleviated by the singlet oxygen scavengers, demonstrating that singlet oxygen played a primary role in this process. Our findings provide a potentially effective disinfecting strategy to combat the environmental viruses using cold atmospheric-pressure plasma and plasma-activated water. Importance Contamination with pathogenic and infectious viruses severely threaten human health and animal husbandry. Current methods for disinfection have different disadvantages, such as inconvenience and contamination of disinfection by-products (e.g. chlorine disinfection). In this study, atmospheric surface plasma in argon mixed with air and plasma-activated water were found to efficiently inactivate bacteriophages, and plasma-activated water still had strong anti-viral activity after prolonged storage. Furthermore, it was shown that bacteriophage inactivation was associated with the damage to nucleic acid and proteins by singlet oxygen. The understanding of the biological effects of plasma-based treatment is useful to inform the development of plasma into a novel disinfecting strategy with convenience and no by-product. Copyright © 2018 Guo et al.

Chlorine Dioxide Inactivation of Cryptosporidium parvum Oocysts and Bacterial Spore Indicators

PubMed Central

Chauret, Christian P.; Radziminski, Chris Z.; Lepuil, Michael; Creason, Robin; Andrews, Robert C.

2001-01-01

Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen. Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts. It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide. This study used both a most-probable-number–cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21°C. The two viability methods produced significantly different results (P < 0.05). Products of disinfectant concentration and contact time (Ct values) of 1,000 mg · min/liter were needed to inactivate approximately 0.5 log10 and 2.0 log10 units (99% inactivation) of C. parvum as measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide. Ct values of 75, 550, and 1,000 mg · min/liter were required to achieve approximately 2.0 log10 units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, including Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity. PMID:11425712

TnBP⁄Triton X-45 Treatment of Plasma for Transfusion Efficiently Inactivates Hepatitis C Virus

PubMed Central

Chou, Ming-Li; Burnouf, Thierry; Chang, Shun-Pang; Hung, Ting-Chun; Lin, Chun-Ching; Richardson, Christopher D.; Lin, Liang-Tzung

2015-01-01

Risk of transmission of hepatitis C virus (HCV) by clinical plasma remains high in countries with a high prevalence of hepatitis C, justifying the implementation of viral inactivation treatments. In this study, we assessed the extent of inactivation of HCV during minipool solvent/detergent (SD; 1% TnBP / 1% Triton X-45) treatment of human plasma. Luciferase-tagged infectious cell culture-derived HCV (HCVcc) particles were used to spike human plasma prior to treatment by SD at 31 ± 0.5°C for 30 min. Samples were taken before and after SD treatment and filtered on a Sep-Pak Plus C18 cartridge to remove the SD agents. Risk of cytotoxicity was assessed by XTT cell viability assay. Viral infectivity was analyzed based on the luciferase signals, 50% tissue culture infectious dose viral titer, and immunofluorescence staining for HCV NS5A protein. Total protein, cholesterol, and triglyceride contents were determined before and after SD treatment and C18 cartridge filtration. Binding analysis, using patient-derived HCV clinical isolates, was also examined to validate the efficacy of the inactivation by SD. SD treatment effectively inactivated HCVcc within 30 min, as demonstrated by the baseline level of reporter signals, total loss of viral infectivity, and absence of viral protein NS5A. SD specifically targeted HCV particles to render them inactive, with essentially no effect on plasma protein content and hemostatic function. More importantly, the efficacy of the SD inactivation method was confirmed against various genotypes of patient-derived HCV clinical isolates and against HCVcc infection of primary human hepatocytes. Therefore, treatment by 1% TnBP / 1% Triton X-45 at 31°C is highly efficient to inactivate HCV in plasma for transfusion, showing its capacity to enhance the safety of therapeutic plasma products. We propose that the methodology used here to study HCV infectivity can be valuable in the validation of viral inactivation and removal processes of human plasma-derived products. PMID:25658612

Pathogen Decontamination of Food Crop Soil: A Review.

PubMed

Gurtler, Joshua B

2017-09-01

The purpose of this review is to delineate means of decontaminating soil. This information might be used to mitigate soil-associated risks of foodborne pathogens. The majority of the research in the published literature involves inactivation of plant pathogens in soil, i.e., those pathogens harmful to fruit and vegetable production and ornamental plants. Very little has been published regarding the inactivation of foodborne human pathogens in crop soil. Nevertheless, because decontamination techniques for plant pathogens might also be useful methods for eliminating foodborne pathogens, this review also includes inactivation of plant pathogens, with appropriate discussion and comparisons, in the hopes that these methods may one day be validated against foodborne pathogens. Some of the major soil decontamination methods that have been investigated and are covered include chemical decontamination (chemigation), solarization, steaming, biofumigation, bacterial competitive exclusion, torch flaming, microwave treatment, and amendment with biochar. Other innovative means of inactivating foodborne pathogens in soils may be discovered and explored in the future, provided that these techniques are economically feasible in terms of chemicals, equipment, and labor. Food microbiology and food safety researchers should reach out to soil scientists and plant pathologists to create links where they do not currently exist and strengthen relationships where they do exist to take advantage of multidisciplinary skills. In time, agricultural output and the demand for fresh produce will increase. With advances in the sensitivity of pathogen testing and epidemiological tracebacks, the need to mitigate preharvest bacterial contamination of fresh produce will become paramount. Hence, soil decontamination technologies may become more economically feasible and practical in light of increasing the microbial safety of fresh produce.

Human pathogens, nosocomial infections, heat-sensitive textile implants, and an innovative approach to deal with them.

PubMed

Cinquemani, Claudio

2011-01-01

Implantable polymers, as used for biomedical applications, inherently have to be sterile. Nonetheless, most implants, particularly those comprised of biomaterials developed in recent years for tissue engineering, are heat sensitive. Therefore, use of hazardous (radio)chemicals--due to lack of alternative methods--is still state of the art for sterilization processes. The drawbacks of these techniques, both drastic and well known, lead to the demand for an alternative sterilization method, which is equally obvious and urgent. High-pressure fluid treatment is a low-temperature technique that is already in use for pasteurization of liquid food products. This paper explores inactivation of vegetative microorganisms, spores, and endotoxins adherent to solid surfaces using compressed CO(2). Pressures ranging from 50 to 100 bar and temperatures from 25 °C to 50 °C were explored to investigate liquid, gaseous or supercritical state. Analysis of variance (ANOVA) and statistical modeling were used to identify the optimum parameter settings for inactivation of pathogenic bacteria and fungi (Candida albicans, Staphylococcus aureus). The addition of small amounts of ozone ensures inactivation of persistent spores (Bacillus stearothermophilus, B. subtilis) up to 10(6) cfu/ml, while endotoxins remain in practically unchanged concentration on the polymer surface. We then discuss environmental issues of the process and inactivation mechanisms. The replacement of conventional chemicals with nonpersistent ones resolves organizational and safety-related issues and protects natural resources as well as handling staff. The pressurized-fluid-based method exhibits mild treatment parameters, thus protecting sensitive textures. Finally, an outlook on possible applications of this innovative technique is presented.

Influence of heavy ions on cell survival, cytogenetic damage and mitochondrial function of human endothelial cells

NASA Astrophysics Data System (ADS)

Ritter, Sylvia; Helm, Alexander; Lee, Ryonfa; Pollet, Dieter; Durante, Marco

There is increasing evidence that there is an elevated risk of cardiovascular disease among atomic bomb survivors and radiotherapy patients, typically developing with a long latency. However, essentially no information is available on the potential cardiovascular risks associated with space radiation, in particular heavy ions. To address this issue, we have chosen human umbilical vein endothelial cells (HUVEC) as a model system. Cells at an early passage number were irradiated with 0.1 to 4 Gy of either 9.8 MeV/u C-ions (LET=170 keV/µm), 91 MeV/u C-ions (LET=29 keV/µm) or 250 kV X-rays. Cells were regularly subcultured up to 40 days (20 population doublings) post-irradiation. Immediately after exposure cell inactivation was deter-mined by the colony forming assay. Furthermore, at selected time-points cytogenetic damage (formation of micronuclei in binucleated cells) and the mitochondrial membrane potential ΨM (flow cytometric analysis following JC-1 staining) were assessed. Measurement of the directly induced radiation damage showed that 9.8 MeV/u and 91 MeV/u C-ions were more effective than X-rays (i.e. about 3 and 2 times, respectively) with respect to cell inactivation or the in-duction of cytogenetic damage. At the subsequent days in the irradiated cultures the number of cells with micronuclei declined to the control level (3-5Altogether our data indicate that under the applied radiation conditions the integrity of mitochondria which play a significant role in the regulation of cardiovascular cell function is not impaired. With respect to directly induced genetic damage C-ions are more effective than X-rays as observed in other cell systems. If the effectiveness of charged particles for the occurrence of late chromosomal damage in endothelial cells is higher than that of sparsely ionizing radiation needs further clarification. The data obtained up to now indicate that sophisticated cytogenetic techniques have to be applied in order to draw any firm conclusions.

The Influence of C-Ions and X-rays on Human Umbilical Vein Endothelial Cells

PubMed Central

Helm, Alexander; Lee, Ryonfa; Durante, Marco; Ritter, Sylvia

2016-01-01

Damage to the endothelium of blood vessels, which may occur during radiotherapy, is discussed as a potential precursor to the development of cardiovascular disease. We thus chose human umbilical vein endothelial cells as a model system to examine the effect of low- and high-linear energy transfer (LET) radiation. Cells were exposed to 250 kV X-rays or carbon ions (C-ions) with the energies of either 9.8 MeV/u (LET = 170 keV/μm) or 91 MeV/u (LET = 28 keV/μm). Subculture of cells was performed regularly up to 46 days (~22 population doublings) post-irradiation. Immediately after exposure, cells were seeded for the colony forming assay. Additionally, at regular intervals, mitochondrial membrane potential (MMP) (JC-1 staining) and cellular senescence (senescence-associated β-galactosidase staining) were assessed. Cytogenetic damage was investigated by the micronucleus assay and the high-resolution multiplex fluorescence in situ hybridization (mFISH) technique. Analysis of radiation-induced damage shortly after exposure showed that C-ions are more effective than X-rays with respect to cell inactivation or the induction of cytogenetic damage (micronucleus assay) as observed in other cell systems. For 9.8 and 91 MeV/u C-ions, relative biological effectiveness values of 2.4 and 1.5 were obtained for cell inactivation. At the subsequent time points, the number of micronucleated cells decreased to the control level. Analysis of chromosomal damage by mFISH technique revealed aberrations frequently involving chromosome 13 irrespective of dose or radiation quality. Disruption of the MMP was seen only a few days after exposure to X-rays or C-ions. Cellular senescence was not altered by radiation at any time point investigated. Altogether, our data indicate that shortly after exposure C-ions were more effective in damaging endothelial cells than X-rays. However, late damage to endothelial cells was not found for the applied conditions and endpoints. PMID:26835420

Anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis show distinct patterns of brain glucose metabolism in 18F-fluoro-2-deoxy-d-glucose positron emission tomography

PubMed Central

2014-01-01

Background Pathogenic autoantibodies targeting the recently identified leucine rich glioma inactivated 1 protein and the subunit 1 of the N-methyl-D-aspartate receptor induce autoimmune encephalitis. A comparison of brain metabolic patterns in 18F-fluoro-2-deoxy-d-glucose positron emission tomography of anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis patients has not been performed yet and shall be helpful in differentiating these two most common forms of autoimmune encephalitis. Methods The brain 18F-fluoro-2-deoxy-d-glucose uptake from whole-body positron emission tomography of six anti-N-methyl-D-aspartate receptor encephalitis patients and four patients with anti-leucine rich glioma inactivated 1 protein encephalitis admitted to Hannover Medical School between 2008 and 2012 was retrospectively analyzed and compared to matched controls. Results Group analysis of anti-N-methyl-D-aspartate encephalitis patients demonstrated regionally limited hypermetabolism in frontotemporal areas contrasting an extensive hypometabolism in parietal lobes, whereas the anti-leucine rich glioma inactivated 1 protein syndrome was characterized by hypermetabolism in cerebellar, basal ganglia, occipital and precentral areas and minor frontomesial hypometabolism. Conclusions This retrospective 18F-fluoro-2-deoxy-d-glucose positron emission tomography study provides novel evidence for distinct brain metabolic patterns in patients with anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis. PMID:24950993

Engineering a horseradish peroxidase C stable to radical attacks by mutating multiple radical coupling sites.

PubMed

Kim, Su Jin; Joo, Jeong Chan; Song, Bong Keun; Yoo, Young Je; Kim, Yong Hwan

2015-04-01

Peroxidases have great potential as industrial biocatalysts. In particular, the oxidative polymerization of phenolic compounds catalyzed by peroxidases has been extensively examined because of the advantage of this method over other conventional chemical methods. However, the industrial application of peroxidases is often limited because of their rapid inactivation by phenoxyl radicals during oxidative polymerization. In this work, we report a novel protein engineering approach to improve the radical stability of horseradish peroxidase isozyme C (HRPC). Phenylalanine residues that are vulnerable to modification by the phenoxyl radicals were identified using mass spectrometry analysis. UV-Vis and CD spectra showed that radical coupling did not change the secondary structure or the active site of HRPC. Four phenylalanine (Phe) residues (F68, F142, F143, and F179) were each mutated to alanine residues to generate single mutants to examine the role of these sites in radical coupling. Despite marginal improvement of radical stability, each single mutant still exhibited rapid radical inactivation. To further reduce inactivation by radical coupling, the four substitution mutations were combined in F68A/F142A/F143A/F179A. This mutant demonstrated dramatic enhancement of radical stability by retaining 41% of its initial activity compared to the wild-type, which was completely inactivated. Structure and sequence alignment revealed that radical-vulnerable Phe residues of HPRC are conserved in homologous peroxidases, which showed the same rapid inactivation tendency as HRPC. Based on our site-directed mutagenesis and biochemical characterization, we have shown that engineering radical-vulnerable residues to eliminate multiple radical coupling can be a good strategy to improve the stability of peroxidases against radical attack. © 2014 Wiley Periodicals, Inc.

Enzymatic and viability RT-qPCR assays for evaluation of enterovirus, hepatitis A virus and norovirus inactivation: Implications for public health risk assessment.

PubMed

Monteiro, S; Santos, R

2018-04-01

To assess the potential of a viability dye and an enzymatic reverse transcription quantitative PCR (RT-qPCR) pretreatment to discriminate between infectious and noninfectious enteric viruses. Enterovirus (EntV), norovirus (NoV) GII.4 and hepatitis A virus (HAV) were inactivated at 95°C for 10 min, and four methods were used to compare the efficiency of inactivation: (i) cell culture plaque assay for HAV and EntV, (ii) RT-qPCR alone, (iii) RT-qPCR assay preceded by RNase treatment, and (iv) pretreatment with a viability dye (reagent D (RD)) followed by RT-qPCR. In addition, heat-inactivated NoV was treated with RD coupled with surfactants to increase the efficiency of the viability dye. No treatment was able to completely discriminate infectious from noninfectious viruses. RD-RT-qPCR reduced more efficiently the detection of noninfectious viruses with little to no removal observed with RNase. RD-RT-qPCR method was the closest to cell culture assay. The combination of surfactants and RD did not show relevant improvements on the removal of inactivated viruses signal compared with viability RT-qPCR, with the exception of Triton X-100. The use of surfactant/RD-RT-qPCR, although not being able to completely remove the signal from noninfectious viral particles, yielded a better estimation of viral infectivity. Surfactant/RD-RT-qPCR may be an advantageous tool for a better detection of infectious viruses with potential significant impact in the risk assessment of the presence of enteric viruses. © 2017 The Society for Applied Microbiology.

Bacteria, mould and yeast spore inactivation studies by scanning electron microscope observations.

PubMed

Rozali, Siti N M; Milani, Elham A; Deed, Rebecca C; Silva, Filipa V M

2017-12-18

Spores are the most resistant form of microbial cells, thus difficult to inactivate. The pathogenic or food spoilage effects of certain spore-forming microorganisms have been the primary basis of sterilization and pasteurization processes. Thermal sterilization is the most common method to inactivate spores present on medical equipment and foods. High pressure processing (HPP) is an emerging and commercial non-thermal food pasteurization technique. Although previous studies demonstrated the effectiveness of thermal and non-thermal spore inactivation, the in-depth mechanisms of spore inactivation are as yet unclear. Live and dead forms of two food spoilage bacteria, a mould and a yeast were examined using scanning electron microscopy before and after the inactivation treatment. Alicyclobacillus acidoterrestris and Geobacillus stearothermophilus bacteria are indicators of acidic foods pasteurization and sterilization processes, respectively. Neosartorya fischeri is a phyto-pathogenic mould attacking fruits. Saccharomyces cerevisiae is a yeast with various applications for winemaking, brewing, baking and the production of biofuel from crops (e.g. sugar cane). Spores of the four microbial species were thermally inactivated. Spores of S. cerevisiae were observed in the ascus and free form after thermal and HPP treatments. Different forms of damage and cell destruction were observed for each microbial spore. Thermal treatment inactivated bacterial spores of A. acidoterrestris and G. stearothermophilus by attacking the inner core of the spore. The heat first altered the membrane permeability allowing the release of intracellular components. Subsequently, hydration of spores, physicochemical modifications of proteins, flattening and formation of indentations occurred, with subsequent spore death. Regarding N. fischeri, thermal inactivation caused cell destruction and leakage of intracellular components. Both thermal and HPP treatments of S. cerevisiae free spores attacked the inner membrane, altering its permeability, and allowing in final stages the transfer of intracellular components to the outside. The spore destruction caused by thermal treatment was more severe than HPP, as HPP had less effect on the spore core. All injured spores have undergone irreversible volume and shape changes. While some of the leakage of spore contents is visible around the deformed but fully shaped spore, other spores exhibited large indentations and were completely deformed, apparently without any contents inside. This current study contributed to the understanding of spore inactivation by thermal and non-thermal processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Homogeneous photocatalytic oxidation of UV filter para-aminobenzoic acid in aqueous solutions.

PubMed

Tsoumachidou, Sophia; Lambropoulou, Dimitra; Poulios, Ioannis

2017-01-01

The presence of personal care product (PCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through graywater; for this reason, efforts are being made to develop methods to inactivate or eliminate this class of substances in the environment. In this work, homogeneous photocatalysis has been applied for the degradation of UV filter para-aminobenzoic acid (PABA), which exists in several types of PCPs, in order to identify the optimum degradation conditions. The oxidation of PABA by photo-Fenton and oxalate-induced photo-Fenton (ferrioxalate) processes was investigated, and the effect of various operating variables has been assessed, i.e., Fe 3+ (0.0035-0.014 g L -1 ), H 2 O 2 (0.025-0.2 g L -1 ), T (280-323 K), and type of radiation (UV-A, visible). Furthermore, experiments under optimal conditions have been performed in order to evaluate the transformation pathways and phytotoxicity of the treated PABA solution.

The calcium current of Helix neuron

PubMed Central

1978-01-01

Calcium current, Ica, was studied in isolated nerve cell bodies of Helix aspersa after suppression of Na+ and K+ currents. The suction pipette method described in the preceding paper was used. Ica rises to a peak value and then subsides exponentially and has a null potential of 150 mV or more and a relationship with [Ca2+]o that is hyperbolic over a small range of [Ca2+]o's. When [Ca2+]i is increased, Ica is reduced disproportionately, but the effect is not hyperbolic. Ica is blocked by extracellular Ni2+, La3+, Cd2+, and Co2+ and is greater when Ba2+ and Sr2+ carry the current. Saturation and blockage are described by a Langmuir adsorption relationship similar to that found in Balanus. Thus, the calcium conductance probably contains a site which binds the ions referred to. The site also appears to be voltage-dependent. Activation and inactivation of Ica are described by first order kinetics, and there is evidence that the processes are coupled. For example, inactivation is delayed slightly in its onset and tau inactivation depends upon the method of study. However, the currents are described equally well by either a noncoupled Hodgkin-Huxley mh scheme or a coupled reaction. Facilitation of Ica by prepulses was not observed. For times up to 50 ms, currents even at small depolarizations were accounted for by suitable adjustment of the activation and inactivation rate constants. PMID:660160

Opposite Effects of Basolateral Amygdala Inactivation on Context-Induced Relapse to Cocaine Seeking after Extinction versus Punishment.

PubMed

Pelloux, Yann; Minier-Toribio, Angelica; Hoots, Jennifer K; Bossert, Jennifer M; Shaham, Yavin

2018-01-03

Studies using the renewal procedure showed that basolateral amygdala (BLA) inactivation inhibits context-induced relapse to cocaine-seeking after extinction. Here, we determined whether BLA inactivation would also inhibit context-induced relapse after drug-reinforced responding is suppressed by punishment, an animal model of human relapse after self-imposed abstinence due to adverse consequences of drug use. We also determined the effect of central amygdala (CeA) inactivation on context-induced relapse.We trained rats to self-administer cocaine for 12 d (6 h/d) in Context A and then exposed them to either extinction or punishment training for 8 d in Context B. During punishment, 50% of cocaine-reinforced lever-presses produced an aversive footshock of increasing intensity (0.1-0.5 or 0.7 mA). We then tested the rats for relapse to cocaine seeking in the absence of cocaine or shock in Contexts A and B after BLA or CeA injections of vehicle or GABA agonists (muscimol-baclofen). We then retrained the rats for cocaine self-administration in Context A, repunished or re-extinguished lever pressing in Context B, and retested for relapse after BLA or CeA inactivation.BLA or CeA inactivation decreased context-induced relapse in Context A after extinction in Context B. BLA, but not CeA, inactivation increased context-induced relapse in Context A after punishment in Context B. BLA or CeA inactivation provoked relapse in Context B after punishment but not extinction. Results demonstrate that amygdala's role in relapse depends on the method used to achieve abstinence and highlights the importance of studying relapse under abstinence conditions that more closely mimic the human condition. SIGNIFICANCE STATEMENT Relapse to drug use during abstinence is often provoked by re-exposure to the drug self-administration environment or context. Studies using the established extinction-reinstatement rodent model of drug relapse have shown that inactivation of the basolateral amygdala inhibits context-induced drug relapse after extinction of the drug-reinforced responding. Here, we determined whether basolateral amygdala inactivation would also inhibit relapse after drug-reinforced responding is suppressed by punishment, a model of human relapse after self-imposed abstinence. Unexpectedly, we found that basolateral amygdala inactivation had opposite effects on relapse provoked by re-exposure to the drug self-administration environment after extinction versus punishment. Our results demonstrate that depending on the historical conditions that lead to abstinence, amygdala activity can either promote or inhibit relapse. Copyright © 2018 the authors 0270-6474/18/380051-09$15.00/0.

GCR Transport in the Brain: Assessment of Self-Shielding, Columnar Damage, and Nuclear Reactions on Cell Inactivation Rates

NASA Technical Reports Server (NTRS)

Shavers, M. R.; Atwell, W.; Cucinotta, F. A.; Badhwar, G. D. (Technical Monitor)

1999-01-01

Radiation shield design is driven by the need to limit radiation risks while optimizing risk reduction with launch mass/expense penalties. Both limitation and optimization objectives require the development of accurate and complete means for evaluating the effectiveness of various shield materials and body-self shielding. For galactic cosmic rays (GCR), biophysical response models indicate that track structure effects lead to substantially different assessments of shielding effectiveness relative to assessments based on LET-dependent quality factors. Methods for assessing risk to the central nervous system (CNS) from heavy ions are poorly understood at this time. High-energy and charge (HZE) ion can produce tissue events resulting in damage to clusters of cells in a columnar fashion, especially for stopping heavy ions. Grahn (1973) and Todd (1986) have discussed a microlesion concept or model of stochastic tissue events in analyzing damage from HZE's. Some tissues, including the CNS, maybe sensitive to microlesion's or stochastic tissue events in a manner not illuminated by either conventional dosimetry or fluence-based risk factors. HZE ions may also produce important lateral damage to adjacent cells. Fluences of high-energy proton and alpha particles in the GCR are many times higher than HZE ions. Behind spacecraft and body self-shielding the ratio of protons, alpha particles, and neutrons to HZE ions increases several-fold from free-space values. Models of GCR damage behind shielding have placed large concern on the role of target fragments produced from tissue atoms. The self-shielding of the brain reduces the number of heavy ions reaching the interior regions by a large amount and the remaining light particle environment (protons, neutrons, deuterons. and alpha particles) may be the greatest concern. Tracks of high-energy proton produce nuclear reactions in tissue, which can deposit doses of more than 1 Gv within 5 - 10 cell layers. Information on rates of cell killing from GCR, including patterns of cell killing from single particle tracks. can provide useful information on expected differences between proton and HZE tracks and clinical experiences with photon irradiation. To model effects on cells in the brain, it is important that transport models accurately describe changes in the GCR due to interactions in the cranium and proximate tissues. We describe calculations of the attenuated GCR particle fluxes at three dose-points in the brain and associated patterns of cell killing using biophysical models. The effects of the brain self-shielding and bone-tissue interface of the skull in modulating the GCR environment are considered. For each brain dose-point, the mass distribution in the surrounding 4(pi) solid angle is characterized using the CAM model to trace 512 rays. The CAM model describes the self-shielding by converting the tissue distribution to mass-equivalent aluminum, and nominal values of spacecraft shielding is considered. Particle transport is performed with the proton, neutron, and heavy-ion transport code HZETRN with the nuclear fragmentation model QMSFRG. The distribution of cells killed along the path of individual GCR ions is modeled using in vitro cell inactivation data for cells with varying sensitivity. Monte Carlo simulations of arrays of inactivated cells are considered for protons and heavy ions and used to describe the absolute number of cell killing events of various magnitude in the brain from the GCR. Included are simulations of positions of inactivated cells from stopping heavy ions and nuclear stars produced by high-energy ions most importantly, protons and neutrons.

[Native, modified, and immobilized chymotrypsin in chaotropic media. Stabilization limits].

PubMed

Panova, A A; Levitskiĭ, V Iu; Mozhaev, V V

1994-07-01

To stabilize alpha-chymotrypsin against irreversible thermal inactivation at high temperatures, methods of covalent modification and multi-point immobilization in combination with the addition of salting-in compounds were used. The upper limit of the protein stability proved to be the same for a combination of the modification and salting-in media and for each of these methods separately. The limit of stabilization reached by means of covalent immobilization is higher than the limit of stabilization reached by two other methods. The greatest stabilization of immobilized alpha-chymotrypsin by the salting-in media (a 10000 fold increase in the native enzyme's stability level) takes place only in the case of the protein with the minimum number of bonds with the support. Stabilization of the enzyme by these methods is explained in terms of the suppression of the conformational inactivation processes.

Inactivation gating of Kv7.1 channels does not involve concerted cooperative subunit interactions.

PubMed

Meisel, Eshcar; Tobelaim, William; Dvir, Meidan; Haitin, Yoni; Peretz, Asher; Attali, Bernard

2018-01-01

Inactivation is an intrinsic property of numerous voltage-gated K + (Kv) channels and can occur by N-type or/and C-type mechanisms. N-type inactivation is a fast, voltage independent process, coupled to activation, with each inactivation particle of a tetrameric channel acting independently. In N-type inactivation, a single inactivation particle is necessary and sufficient to occlude the pore. C-type inactivation is a slower process, involving the outermost region of the pore and is mediated by a concerted, highly cooperative interaction between all four subunits. Inactivation of Kv7.1 channels does not exhibit the hallmarks of N- and C-type inactivation. Inactivation of WT Kv7.1 channels can be revealed by hooked tail currents that reflects the recovery from a fast and voltage-independent inactivation process. However, several Kv7.1 mutants such as the pore mutant L273F generate an additional voltage-dependent slow inactivation. The subunit interactions during this slow inactivation gating remain unexplored. The goal of the present study was to study the nature of subunit interactions along Kv7.1 inactivation gating, using concatenated tetrameric Kv7.1 channel and introducing sequentially into each of the four subunits the slow inactivating pore mutation L273F. Incorporating an incremental number of inactivating mutant subunits did not affect the inactivation kinetics but slowed down the recovery kinetics from inactivation. Results indicate that Kv7.1 inactivation gating is not compatible with a concerted cooperative process. Instead, adding an inactivating subunit L273F into the Kv7.1 tetramer incrementally stabilizes the inactivated state, which suggests that like for activation gating, Kv7.1 slow inactivation gating is not a concerted process.

Effect of different baculovirus inactivation procedures on the integrity and immunogenicity of porcine parvovirus-like particles.

PubMed

Rueda, P; Fominaya, J; Langeveld, J P; Bruschke, C; Vela, C; Casal, J I

2000-11-22

We have demonstrated earlier the usefulness of recombinant porcine parvovirus (PPV) virus-like particles (VLPs) as an efficient recombinant vaccine for PPV. Here, we have demonstrated that preparations of PPV VLPs could be contaminated by recombinant baculoviruses. Since these baculoviruses can be a problem for the registration and safety requirements of the recombinant vaccine, we have tested different baculovirus inactivation strategies, studying simultaneously the integrity and immunogenicity of the VLPs. These methods were pasteurization, treatment with detergents and alkylation with binary ethylenimine (BEI). The structural and functional integrity of the PPV VLPs after the inactivation treatments were analyzed by electron microscopy, hemagglutination, double antibody sandwich (DAS)-ELISA and immunogenicity studies. Binary ethylenimine and Triton X-100 inactivated particles maintained all the original structural and antigenic properties. In addition, PPV VLPs were subjected to size-exclusion chromatography to analyze the presence of VP2 monomers or any other contaminant. The resulting highly purified material was used as the standard of reference to quantify PPV VLPs in order to determine the dose of vaccine by DAS-ELISA. After immunization experiments in guinea pigs, the antibody titers obtained with all the inactivation procedures were very similar. Triton X-100 treatment was selected for further testing in animals because of the speed, simplicity and safety of the overall procedure.

Inactivation of viruses by pasteurization at 60 °C for 10 h with and without 40% glucose as stabilizer during a new manufacturing process of α2-Macroglobulin from Cohn Fraction IV.

PubMed

Huangfu, Chaoji; Ma, Yuyuan; Jia, Junting; Lv, Maomin; Zhu, Fengxuan; Ma, Xiaowei; Zhao, Xiong; Zhang, Jingang

2017-03-01

Pasteurization is regularly used to inactivate viruses for the safety of plasma derivatives. Influence of pasteurization at 60 °C for 10 h on α2-Macroglobulin activity and virus inactivation were studied. With 40% sugar as stabilizers more than 70% α2-Macroglobulin activity was reserved after pasteurization compared with 20% in control. Glucose presented a better activity protection effect than sucrose and maltose. By pasteurization without stabilizer the virus titers of pseudorabies virus, Sindbis virus, porcine parvovirus and encephalomyocarditis virus were reduced more than 5.88 log 10 , 7.50 log 10 , 4.88 log 10 , and 5.63 log 10 respectively within 2 h. By pasteurization with 40% glucose vesicular stomatitis virus was inactivated more than 5.88 log 10 within 1 h. Only 2.71 log 10 reduction was achieved for encephalomyocarditis virus after 10 h. 40% glucose protected α2-M activity and viruses simultaneously from pasteurization. Other viral inactivation methods need to be incorporated to ensure viral safety of this manufacturing process of α2-Macroglobulin. Copyright © 2017 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

UV-C light inactivation and modeling kinetics of Alicyclobacillus acidoterrestris spores in white grape and apple juices.

PubMed

Baysal, Ayse Handan; Molva, Celenk; Unluturk, Sevcan

2013-09-16

In the present study, the effect of short wave ultraviolet light (UV-C) on the inactivation of Alicyclobacillus acidoterrestris DSM 3922 spores in commercial pasteurized white grape and apple juices was investigated. The inactivation of A. acidoterrestris spores in juices was examined by evaluating the effects of UV light intensity (1.31, 0.71 and 0.38 mW/cm²) and exposure time (0, 3, 5, 7, 10, 12 and 15 min) at constant depth (0.15 cm). The best reduction (5.5-log) was achieved in grape juice when the UV intensity was 1.31 mW/cm². The maximum inactivation was approximately 2-log CFU/mL in apple juice under the same conditions. The results showed that first-order kinetics were not suitable for the estimation of spore inactivation in grape juice treated with UV-light. Since tailing was observed in the survival curves, the log-linear plus tail and Weibull models were compared. The results showed that the log-linear plus tail model was satisfactorily fitted to estimate the reductions. As a non-thermal technology, UV-C treatment could be an alternative to thermal treatment for grape juices or combined with other preservation methods for the pasteurization of apple juice. © 2013 Elsevier B.V. All rights reserved.

Inactivation efficiency of plasmid-encoded antibiotic resistance genes during water treatment with chlorine, UV, and UV/H2O2.

PubMed

Yoon, Younggun; Chung, Hay Jung; Wen Di, Doris Yoong; Dodd, Michael C; Hur, Hor-Gil; Lee, Yunho

2017-10-15

This study assessed the inactivation efficiency of plasmid-encoded antibiotic resistance genes (ARGs) both in extracellular form (e-ARG) and present within Escherichia coli (intracellular form, i-ARG) during water treatment with chlorine, UV (254 nm), and UV/H 2 O 2 . A quantitative real-time PCR (qPCR) method was used to quantify the ARG damage to amp R (850 bp) and kan R (806 bp) amplicons, both of which are located in the pUC4K plasmid. The plate count and flow cytometry methods were also used to determine the bacterial inactivation parameters, such as culturability and membrane damage, respectively. In the first part of the study, the kinetics of E. coli inactivation and ARG damage were determined in phosphate buffered solutions. The ARG damage occurred much more slowly than E. coli inactivation in all cases. To achieve 4-log reduction of ARG concentration at pH 7, the required chlorine exposure and UV fluence were 33-72 (mg × min)/L for chlorine and 50-130 mJ/cm 2 for UV and UV/H 2 O 2 . After increasing pH from 7 to 8, the rates of ARG damage decreased for chlorine, while they did not vary for UV and UV/H 2 O 2 . The i-ARGs mostly showed lower rates of damage compared to the e-ARGs due to the protective roles of cellular components against oxidants and UV. The contribution of OH radicals to i-ARG damage was negligible in UV/H 2 O 2 due to significant OH radical scavenging by cellular components. In all cases, the ARG damage rates were similar for amp R versus kan R , except for the chlorination of e-ARGs, in which the damage to amp R occurred faster than that to kan R . Chlorine and UV dose-dependent ARG inactivation levels determined in a wastewater effluent matrix could be reasonably explained by the kinetic data obtained from the phosphate buffered solutions and the expected oxidant (chlorine and OH radicals) demands by water matrix components. These results can be useful in optimizing chlorine and UV-based disinfection systems to achieve ARG inactivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dual effects of single-walled carbon nanotubes coupled with near-infrared radiation on Bacillus anthracis spores: inactivates spores and stimulates the germination of surviving spores

PubMed Central

2013-01-01

Background Bacillus anthracis is a pathogen that causes life-threatening disease--anthrax. B. anthracis spores are highly resistant to extreme temperatures and harsh chemicals. Inactivation of B. anthracis spores is important to ensure the environmental safety and public health. The 2001 bioterrorism attack involving anthrax spores has brought acute public attention and triggered extensive research on inactivation of B. anthracis spores. Single-walled carbon nanotubes (SWCNTs) as a class of emerging nanomaterial have been reported as a strong antimicrobial agent. In addition, continuous near infrared (NIR) radiation on SWCNTs induces excessive local heating which can enhance SWCNTs’ antimicrobial effect. In this study, we investigated the effects of SWCNTs coupled with NIR treatment on Bacillus anthracis spores. Results and discussion The results showed that the treatment of 10 μg/mL SWCNTs coupled with 20 min NIR significantly improved the antimicrobial effect by doubling the percentage of viable spore number reduction compared with SWCNTs alone treatment (88% vs. 42%). At the same time, SWCNTs-NIR treatment activated the germination of surviving spores and their dipicolinic acid (DPA) release during germination. The results suggested the dual effect of SWCNTs-NIR treatment on B. anthracis spores: enhanced the sporicidal effect and stimulated the germination of surviving spores. Molecular level examination showed that SWCNTs-NIR increased the expression levels (>2-fold) in 3 out of 6 germination related genes tested in this study, which was correlated to the activated germination and DPA release. SWCNTs-NIR treatment either induced or inhibited the expression of 3 regulatory genes detected in this study. When the NIR treatment time was 5 or 25 min, there were 3 out of 7 virulence related genes that showed significant decrease on expression levels (>2 fold decrease). Conclusions The results of this study demonstrated the dual effect of SWCNTs-NIR treatment on B. anthracis spores, which enhanced the sporicidal effect and stimulated the germination of surviving spores. SWCNTs-NIR treatment also altered the expression of germination, regulatory, and virulence-related genes in B. anthracis. PMID:23965258

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility

PubMed Central

Khodadad, Christina L.; Wong, Gregory M.; James, Leandro M.; Thakrar, Prital J.; Lane, Michael A.; Catechis, John A.

2017-01-01

Abstract Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 107 spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility. The payload spent 8 h at ∼31 km above sea level, exposing bacterial spores to the stratosphere. We found that within 120 and 240 min, spore viability was significantly reduced by 2 and 4 orders of magnitude, respectively. By 480 min, <0.001% of spores carried to the stratosphere remained viable. Our balloon flight results predict that most terrestrial bacteria would be inactivated within the first sol on Mars if contaminated spacecraft surfaces receive direct sunlight. Unfortunately, an instrument malfunction prevented the acquisition of UV light measurements during our balloon mission. To make up for the absence of radiometer data, we calculated a stratosphere UV model and conducted ground tests with a 271.1 nm UVC light source (0.5 W/m2), observing a similarly rapid inactivation rate when using a lower number of contaminants (640 spores per sample). The starting concentration of spores and microconfiguration on hardware surfaces appeared to influence survivability outcomes in both experiments. With the relatively few spores that survived the stratosphere, we performed a resequencing analysis and identified three single nucleotide polymorphisms compared to unexposed controls. It is therefore plausible that bacteria enduring radiation-rich environments (e.g., Earth's upper atmosphere, interplanetary space, or the surface of Mars) may be pushed in evolutionarily consequential directions. Key Words: Planetary protection—Stratosphere—Balloon—Mars analog environment—E-MIST payload—Bacillus pumilus SAFR-032. Astrobiology 17, 337–350. PMID:28323456

Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region.

PubMed

Ndounla, J; Pulgarin, C

2014-09-15

The photo-disinfection of water from two different wells (W1, pH: 4.6-5.1 ± 0.02) and (W2 pH: 5.6-5.7 ± 0.02) was carried out during the rainy season at Ouagadougou-Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO3(-) concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO3(-) concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and ammonia. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultraviolet-Induced Decrease in Integration of Haemophilus influenzae Transforming Deoxyribonucleic Acid in Sensitive and Resistant Cells

PubMed Central

Muhammed, Amir; Setlow, Jane K.

1970-01-01

The decrease in integration of transforming deoxyribonucleic acid (DNA) caused by ultraviolet irradiation of the DNA was found to be independent of the presence or absence of excision repair in the recipient cell. Much of the ultraviolet-induced inhibition of integration resulted from the presence in the transforming DNA of pyrimidine dimers, as judged by the photoreactivability of the inhibition with yeast photoreactivating enzyme. The inhibition of integration made only a small contribution to the inactivation of transforming ability of the DNA by ultraviolet radiation. PMID:5308769

Mechanism of lethal action of 2,450-MHz radiation on microorganisms.

PubMed Central

Vela, G R; Wu, J F

1979-01-01

Various bacteria, actinomycetes, fungi, and bacteriophages were exposed to microwaves of 2,450 +/- 20 MHz in the presence and in the absence of water. It was found that microorganisms were inactivated only when in the presence of water and that dry or lyophilized organisms were not affected even by extended exposures. The data presented here prove that microorganisms are killed by "thermal effect" only and that, most likely, there is no "nonthermal effect"; cell constituents other than water do not absorb sufficient energy to kill microbial cells. PMID:453828

Establishment of a biological reference preparation for hepatitis A vaccine (inactivated, non-adsorbed).

PubMed

Stalder, J; Costanzo, A; Daas, A; Rautmann, G; Buchheit, K-H

2010-04-01

A reference standard calibrated in International Units (IU) is needed for the in vitro potency assay of hepatitis A vaccines prepared by formalin-inactivation of purified hepatitis A virus grown in cell cultures. Thus, a project was launched by the European Directorate for the Quality of Medicines & HealthCare (EDQM) to establish one or more non-adsorbed inactivated hepatitis A vaccine reference preparation(s) as working standard(s), calibrated against the 1st International Standard (IS), for the in vitro potency assay (ELISA) of all vaccines present on the European market. Four non-adsorbed liquid preparations of formalin-inactivated hepatitis A antigen with a known antigen content were obtained from 3 manufacturers as candidate Biological Reference Preparations (BRPs). Thirteen laboratories participated in the collaborative study. They were asked to use an in vitro ELISA method adapted from a commercially available kit for the detection of antibodies to hepatitis A virus. In-house validated assays were to be run in parallel, where available. Some participants also included commercially available hepatitis A vaccines in the assays, after appropriate desorption. During the collaborative study, several participants using the standard method were faced with problems with some of the most recent lots of the test kits. Due to these problems, the standard method did not perform satisfactorily and a high number of assays were invalid, whereas the in-house methods appeared to perform better. Despite this, the overall mean results of the valid assays using both methods were in agreement. Nonetheless, it was decided to base the assignment of the potency values on the in-house methods only. The results showed that all candidate BRPs were suitable for the intended purpose. However, based on availability of the material and on the results of end-product testing, 2 candidate reference preparations, Samples C and D, were selected. Both were from the same batch but filled on different days; no statistically significant difference in potency was observed. They were thus combined in 1 single batch. The candidate preparation (Sample C/D) was adopted at the June 2009 session of the European Pharmacopoeia (Ph. Eur.) Commission as the Ph. Eur. BRP batch 1 for hepatitis A vaccine (inactivated, non-adsorbed), with an assigned potency of 12 IU/ml for in vitro antigen content assays. Accelerated degradation studies have been initiated. The preliminary data show that the BRP is stable at the recommended storage temperature (< -50 degrees C). The BRP will be monitored at regular intervals throughout its lifetime.

Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

NASA Astrophysics Data System (ADS)

Čeřovský, M.; Khun, J.; Rusová, K.; Scholtz, V.; Soušková, H.

2013-09-01

The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.

Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Čeřovský, M., E-mail: scholtz@aldebaran.cz; Khun, J.; Rusová, K.

2013-09-15

The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperaturemore » plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.« less

Single track effects, Biostack and risk assessment

NASA Technical Reports Server (NTRS)

Curtis, S. B.; Chatterjee, A. (Principal Investigator)

1994-01-01

The scientific career of Prof. Bucker has spanned a very exciting period in the fledgling science of Space Radiation Biology. The capability for placing biological objects in space was developed, and the methods for properly packaging, retrieving and analyzing them were worked out. Meaningful results on the effects of radiation were obtained for the first time. In fact, many of the successful techniques and methodologies for handling biological samples were developed in Prof. Bucker's laboratories, as attested by the extensive Biostack program. He was the first to suggest and successfully carry out experiments in space directly aimed at measuring effects of single tracks of high-energy heavy galactic cosmic rays by specifically identifying whether or not the object had been hit by a heavy particle track. Because the "hit" frequencies of heavy galactic cosmic rays to cell nuclei in the bodies of space travelers will be low, it is expected that any effects to humans on the cellular level will be dominated by single-track cell traversals. This includes the most important generally recognized late effect of space radiation exposure: radiation-induced cancer. This paper addresses the single-track nature of the space radiation environment, and points out the importance of single "hits" in the evaluation of radiation risk for long-term missions occurring outside the earth's magnetic field. A short review is made of biological objects found to show increased effects when "hit" by a single heavy charged-particle in space. A brief discussion is given of the most provocative results from the bacterial spore Bacillus subtilis: experimental evidence that tracks can affect biological systems at much larger distances from the trajectory than previously suspected, and that the resultant inactivation cross section in space calculated for this system is very large. When taken at face value, the implication of these results, when compared to those from experiments performed at ground-based accelerators with beams at low energies in the same LET range, is that high-energy particles can exert their influence a surprising distance from their trajectory and the inactivation cross sections are some 20 times larger than expected. Clearly, beams from high-energy heavy-ion accelerators should be used to confirm these results. For those end points that can also be caused by low-LET beams such as high-energy protons, it is important to measure their action cross sections as well. The ratio of the cross sections for a high-LET beam to that of a low-LET beam is an interesting experimental ratio and, we suggest, of more intrinsic interest than the RBE (Relative Biological Effectiveness). It is a measure of the "biological" importance of one particle type relative to another particle type. This ratio will be introduced and given the name RPPE (Relative Per Particle Effectiveness). Values of RPPE have appeared in the literature and will be discussed. A rather well-known value of this quantity (13,520) has been suggested for the RPPE of high-energy iron ions to high-energy protons. This value was suggested by Letaw et al. Nature 330, 709-710 (1987)] we will call it the Letaw limit. It will be discussed in terms of the importance of the heavy-ion component vs light-ion component of the galactic cosmic rays. It is also pointed out, however, that there may be unique effects from single tracks of heavy ions that do not occur from light-ion tracks. For such effects, the concepts of both RBE and RPPE lose their meaning.

Numerical study of droplet evaporation in an acoustic levitator

NASA Astrophysics Data System (ADS)

Bänsch, Eberhard; Götz, Michael

2018-03-01

We present a finite element method for the simulation of all relevant processes of the evaporation of a liquid droplet suspended in an acoustic levitation device. The mathematical model and the numerical implementation take into account heat and mass transfer across the interface between the liquid and gaseous phase and the influence of acoustic streaming on this process, as well as the displacement and deformation of the droplet due to acoustic radiation pressure. We apply this numerical method to several theoretical and experimental examples and compare our results with the well-known d2-law for the evaporation of spherical droplets and with theoretical predictions for the acoustic streaming velocity. We study the influence of acoustic streaming on the distribution of water vapor and temperature in the levitation device, with special attention to the vapor distribution in the emerging toroidal vortices. We also compare the evaporation rate of a droplet with and without acoustic streaming, as well as the evaporation rates in dependence of different temperatures and sound pressure levels. Finally, a simple model of protein inactivation due to heat damage is considered and studied for different evaporation settings and their respective influence on protein damage.

The non-targeted effects of radiation are perpetuated by exosomes.

PubMed

Al-Mayah, Ammar; Bright, Scott; Chapman, Kim; Irons, Sarah; Luo, Ping; Carter, David; Goodwin, Edwin; Kadhim, Munira

2015-02-01

Exosomes contain cargo material from endosomes, cytosol, plasma membrane and microRNA molecules, they are released by a number of non-cancer and cancer cells into both the extracellular microenvironment and body fluids such as blood plasma. Recently we demonstrated radiation-induced non-targeted effects [NTE: genomic instability (GI) and bystander effects (BE)] are partially mediated by exosomes, particularly the RNA content. However the mechanistic role of exosomes in NTE is yet to be fully understood. The present study used MCF7 cells to characterise the longevity of exosome-induced activity in the progeny of irradiated and unirradiated bystander cells. Exosomes extracted from conditioned media of irradiated and bystander progeny were added to unirradiated cells. Analysis was carried out at 1 and 20/24 population doublings following medium/exosome transfer for DNA/chromosomal damage. Results confirmed exosomes play a significant role in mediating NTE of ionising radiation (IR). This effect was remarkably persistent, observed >20 doublings post-irradiation in the progeny of bystander cells. Additionally, cell progeny undergoing a BE were themselves capable of inducing BE in other cells via exosomes they released. Furthermore we investigated the role of exosome cargo. Culture media from cells exposed to 2 Gy X-rays was subjected to ultracentrifugation and four inoculants prepared, (a) supernatants with exosomes removed, and pellets with (b) exosome proteins denatured, (c) RNA degraded, and (d) a combination of protein-RNA inactivation. These were added to separate populations of unirradiated cells. The BE was partially inhibited when either exosome protein or exosome RNA were inactivated separately, whilst combined RNA-protein inhibition significantly reduced or eliminated the BE. These results demonstrate that exosomes are associated with long-lived signalling of the NTE of IR. Both RNA and protein molecules of exosomes work in a synergistic manner to initiate NTE, spread these effects to naïve cells, and perpetuate GI in the affected cells. Copyright © 2015. Published by Elsevier B.V.

Inactivation of West Nile Virus in Serum with Heat, Ionic Detergent, and Reducing Agent for Proteomic Applications (Open Access Publisher’s Version)

DTIC Science & Technology

2017-05-19

LightCycler® 96 desktop software. Positive and negative samples were identified using the “ Qualitative Detection” analysis function using the default...Institute of Infectious Diseases, Fort Detrick, MD 21702, United States A R T I C L E I N F O Keywords: West Nile virus Virus inactivation Sample buffer... samples using a commercially available SDS- PAGE sample buffer for proteomic studies. Using this method, we demonstrate its utility by identification

Liquid Water Restricts Habitability in Extreme Deserts.

PubMed

Cockell, Charles S; Brown, Sarah; Landenmark, Hanna; Samuels, Toby; Siddall, Rebecca; Wadsworth, Jennifer

2017-04-01

Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water. Key Words: Deserts-Extremophiles-Stress-High temperatures-UV radiation-Desiccation. Astrobiology 17, 309-318.

The ultraviolet environment of Mars: biological implications past, present, and future.

PubMed

Cockell, C S; Catling, D C; Davis, W L; Snook, K; Kepner, R L; Lee, P; McKay, C P

2000-08-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

The ultraviolet environment of Mars: biological implications past, present, and future

NASA Technical Reports Server (NTRS)

Cockell, C. S.; Catling, D. C.; Davis, W. L.; Snook, K.; Kepner, R. L.; Lee, P.; McKay, C. P.

2000-01-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

Influence of gamma radiation onto polymeric matrix with papain

NASA Astrophysics Data System (ADS)

Zulli, Gislaine; Lopes, Patrícia Santos; Velasco, Maria Valéria Robles; Alcântara, Mara Tânia Silva; Rogero, Sizue Ota; Lugao, Ademar Benévolo; Mathor, Monica Beatriz

2010-03-01

Papain is a proteolytic enzyme that has been widely used as debridement agent for scars and wound healing treatment. However, papain presents low stability, which limits its use to extemporaneous or short shelf-life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system that could be used as medical device. Since these systems must be sterile, gamma radiation is an interesting option and presents advantages in relation to conventional agents: no radioactive residues are formed; the product can be sterilized inside the final packaging and has an excellent reliability. The normative reference for the establishment of the sterilizing dose determines 25 kGy as the inactivation dose for viable microorganisms. A silicone dispersion was selected to prepare membranes containing 2% (w/w) papain. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify whether gamma radiation interferes with the drug-releasing profile. Results showed that irradiation does not affect significantly papain release and its activity. Therefore papain shows radioresistance in the irradiation conditions applied. In conclusion, gamma radiation can be easily used as sterilizing agent without affecting the papain release profile and its activity onto the biocompatible device is studied.

Mold and aflatoxin reduction by gamma radiation of packed hot peppers and their evolution during storage.

PubMed

Iqbal, Qumer; Amjad, Muhammad; Asi, Muhammad Rafique; Ariño, Agustin

2012-08-01

The effect of gamma radiation on moisture content, total mold counts, Aspergillus counts, and aflatoxins of three hot pepper hybrids (Sky Red, Maha, and Wonder King) was investigated. Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and stored at 25°C for 90 days. Gamma radiation proved to be effective in reducing total mold and Aspergillus counts in a dose-dependent relationship. Total mold counts in irradiated peppers immediately after treatments were significantly lowered compared with those in nonirradiated samples, achieving 90 and 99% reduction at 2- and 4-kGy doses, respectively. Aspergillus counts were significantly reduced, by 93 and 97%, immediately after irradiation at doses of 2 and 4 kGy, respectively. A radiation dose of 6 kGy completely eliminated the population of total molds and Aspergillus fungi. The evolution of total molds in control and irradiated samples indicated no further fungal proliferation during 3 months of storage at 25°C. Aflatoxin levels were slightly affected by radiation doses of 2 and 4 kGy and showed a nonsignificant reduction of 6% at the highest radiation dose of 6 kGy. The distinct effectiveness of gamma radiation in molds and aflatoxins can be explained by the target theory of food irradiation, which states that the likelihood of a microorganism or a molecule being inactivated by gamma rays increases as its size increases.

Solar Photothermal Disinfection using Broadband-Light Absorbing Gold Nanoparticles and Carbon Black.

PubMed

Loeb, Stephanie; Li, Chuanhao; Kim, Jae-Hong

2018-01-02

A simple heat treatment, perhaps the most globally recognized point-of-use water sterilization method, is seemingly effective against all major pathogens of concern, but bulk water boiling is not energy efficient or sustainable. Herein, we present the first application of solar-to-thermal converting nanomaterials for the direct inactivation of bacteria and viruses in drinking water through the application of Au nanorods, carbon black, and Au nanorod-carbon black composite materials as light absorbers. With broad absorption bands spanning the visible and near-infrared wavelengths, at sufficient concentrations, these nanoparticles induce multiple scattering events, increasing photon absorption probability and concentrating the light within a small spatial domain, leading to localized, intense heating that inactivates microorganisms in close proximity. Moving toward practical device design, we have developed a facile silane immobilization approach to fabricate films with densely packed layers of photothermal nanomaterials. Our results suggest that upon irraditaion with simulated solar light, these films can thermally inactivate bacteria and viruses, as demonstrated through the inactivation of surrogate organisms Escherichia coli K-12, and bacteriophages MS2 and PR772.

Synthesis, Characterization, and Antimicrobial Efficacy of Photomicrobicidal Cellulose Paper.

PubMed

Carpenter, Bradley L; Scholle, Frank; Sadeghifar, Hasan; Francis, Aaron J; Boltersdorf, Jonathan; Weare, Walter W; Argyropoulos, Dimitris S; Maggard, Paul A; Ghiladi, Reza A

2015-08-10

Toward our goal of scalable, antimicrobial materials based on photodynamic inactivation, paper sheets comprised of photosensitizer-conjugated cellulose fibers were prepared using porphyrin and BODIPY photosensitizers, and characterized by spectroscopic (infrared, UV-vis diffuse reflectance, inductively coupled plasma optical emission) and physical (gel permeation chromatography, elemental, and thermal gravimetric analyses) methods. Antibacterial efficacy was evaluated against Staphylococcus aureus (ATCC-2913), vancomycin-resistant Enterococcus faecium (ATCC-2320), Acinetobacter baumannii (ATCC-19606), Pseudomonas aeruginosa (ATCC-9027), and Klebsiella pneumoniae (ATCC-2146). Our best results were achieved with a cationic porphyrin-paper conjugate, Por((+))-paper, with inactivation upon illumination (30 min, 65 ± 5 mW/cm(2), 400-700 nm) of all bacterial strains studied by 99.99+% (4 log units), regardless of taxonomic classification. Por((+))-paper also inactivated dengue-1 virus (>99.995%), influenza A (∼ 99.5%), and human adenovirus-5 (∼ 99%). These results demonstrate the potential of cellulose materials to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

Exploring photoinactivation of microbial biofilms using laser scanning microscopy and confined two-photon excitation.

PubMed

Thomsen, Hanna; Graf, Fabrice E; Farewell, Anne; Ericson, Marica B

2018-05-21

One pertinent complication in bacterial infection is the growth of biofilms, i.e., communities of surface-adhered bacteria resilient to antibiotics. Photodynamic inactivation has been proposed as an alternative to antibiotic treatment; however, novel techniques complementing standard efficacy measures are required. Herein, we present an approach employing multiphoton microscopy complemented with Airyscan super-resolution microscopy, to visualize the distribution of curcumin in Staphylococcus epidermidis biofilms. The effects of complexation of curcumin with hydroxypropyl-γ-cyclodextrin (HPγCD) were studied. It was shown that HPγCD-curcumin demonstrated higher bioavailability in the biofilms compared to curcumin, without affecting the subcellular uptake. Spectral quantification following photodynamic inactivation demonstrates a method for monitoring elimination of biofilms in real time using noninvasive 3D imaging. Additionally, spatially confined two-photon inactivation was demonstrated for the first time in biofilms. These results support the feasibility of advanced optical microscopy as a sensitive tool for evaluating treatment efficacy in biofilms towards improved mechanistic studies of photodynamic inactivation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

PEF and UV combined system for pathogen microorganisms inactivation in liquid food products

NASA Astrophysics Data System (ADS)

Cramariuc, R.; Popa, M.; Tudorache, A.; Brînduşe, E.; Kontek, A.; Mitelut, A.; Fotescu, L.; Cramariuc, B.; Geicu, M.; Nisiparu, L.

2011-06-01

Pulsed electrical field (PEF) treatment is a non-thermal food preservation technology based on the use of the electrical field in impulses applied in order to inactivate and control pathogen microorganisms in foods. This technology is highly appreciated for its ability to prolong the shelf life of the treated product without the use of heat and also for its ability to preserve the product's sensory qualities and nutritional value as well as for the microbiological control of the treated products. This paper presents the PEF and UV treatment methods, or a combination between the two, for microbe inactivation in liquid products. The experiments were carried out using yeasts, lactic bacteria and acetic bacteria in the following systems: stand-alone treatments (PEF or UV) or in combination (UV+PEF or PEF+UV). The results of these experiments showed that one can obtain total inactivation of microorganisms using the combined UV+PEF system, thus leading to the possibility of increasing liquid food products quality as compared to the quality obtained using thermal pasteurization.

Transient heating of expressed breast milk up to 65°C inactivates HIV-1 in milk: a simple, rapid, and cost-effective method to prevent postnatal transmission.

PubMed

Hoque, Sheikh Ariful; Hoshino, Hiroo; Anwar, Kazi Selim; Tanaka, Atsushi; Shinagawa, Masahiko; Hayakawa, Yuko; Okitsu, Shoko; Wada, Yuichi; Ushijima, Hiroshi

2013-02-01

The postnatal transmission of human immunodeficiency virus (HIV) from mothers to children occurs through breastfeeding. Although heat treatment of expressed breast milk is a promising approach to make breastfeeding safer, it is still not popular, mainly because the recommended procedures are difficult to follow, or time-consuming, or because mothers do not know which temperature is sufficient to inactivate HIV without destroying the nutritional elements of milk. To overcome these drawbacks, a simple and rapid method of heat treatment that a mother could perform with regular household materials applying her day-to-day art of cooking was examined. This structured experiment has demonstrated that both cell-free and cell-associated HIV type 1 (HIV-1) in expressed breast milk could be inactivated once the temperature of milk reached 65°C. Furthermore, a heating method as simple as heating the milk in a pan over a stove to 65°C inhibited HIV-1 transmission retaining milk's nutritional key elements, for example, total protein, IgG, IgA, and vitamin B(12) . This study has highlighted a simple, handy, and cost-effective method of heat treatment of expressed breast milk that mothers infected with HIV could apply easily and with more confidence. Copyright © 2012 Wiley Periodicals, Inc.

A user-friendly and scalable process to prepare a ready-to-use inactivated vaccine: the example of heartwater in ruminants under tropical conditions.

PubMed

Marcelino, Isabel; Lefrançois, Thierry; Martinez, Dominique; Giraud-Girard, Ken; Aprelon, Rosalie; Mandonnet, Nathalie; Gaucheron, Jérôme; Bertrand, François; Vachiéry, Nathalie

2015-01-29

The use of cheap and thermoresistant vaccines in poor tropical countries for the control of animal diseases is a key issue. Our work aimed at designing and validating a process for the large-scale production of a ready-to-use inactivated vaccine for ruminants. Our model was heartwater caused by the obligate intracellular bacterium Ehrlichia ruminantium (ER). The conventional inactivated vaccine against heartwater (based on whole bacteria inactivated with sodium azide) is prepared immediately before injection, using a syringe-extrusion method with Montanide ISA50. This is a fastidious time-consuming process and it limits the number of vaccine doses available. To overcome these issues, we tested three different techniques (syringe, vortex and homogenizer) and three Montanide ISA adjuvants (50, 70 and 70M). High-speed homogenizer was the optimal method to emulsify ER antigens with both ISA70 and 70M adjuvants. The emulsions displayed a good homogeneity (particle size below 1 μm and low phase separation), conductivity below 10 μS/cm and low antigen degradation at 4 °C for up to 1 year. The efficacy of the different formulations was then evaluated during vaccination trials on goats. The inactivated ER antigens emulsified with ISA70 and ISA70M in a homogenizer resulted in 80% and 100% survival rates, respectively. A cold-chain rupture assay using ISA70M+ER was performed to mimic possible field conditions exposing the vaccine at 37 °C for 4 days before delivery. Surprisingly, the animal survival rate was still high (80%). We also observed that the MAP-1B antibody response was very similar between animals vaccinated with ISA70+ER and ISA70M+ER emulsions, suggesting a more homogenous antigen distribution and presentation in these emulsions. Our work demonstrated that the combination of ISA70 or ISA70M and homogenizer is optimal for the production of an effective ready-to-use inactivated vaccine against heartwater, which could easily be produced on an industrial scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

Inactivation and injury assessment of Escherichia coli during solar and photocatalytic disinfection in LDPE bags.

PubMed

Dunlop, P S M; Ciavola, M; Rizzo, L; Byrne, J A

2011-11-01

Solar disinfection (SODIS) of Escherichia coli suspensions in low-density polyethylene bag reactors was investigated as a low-cost disinfection method suitable for application in developing countries. The efficiency of a range of SODIS reactor configurations was examined (single skin (SS), double skin, black-backed single skin, silver-backed single skin (SBSS) and composite-backed single skin) using E. coli suspended in model and real surface water. Titanium dioxide was added to the reactors to improve the efficiency of the SODIS process. The effect of turbidity was also assessed. In addition to viable counts, E. coli injury was characterised through spread-plate analysis using selective and non-selective media. The optimal reactor configuration was determined to be the SBSS bag (t(50)=9.0min) demonstrating the importance of UVA photons, as opposed to infrared in the SODIS disinfection mechanism. Complete inactivation (6.5-log) was achieved in the presence of turbidity (50NTU) using the SBSS bag within 180min simulated solar exposure. The addition of titanium dioxide (0.025gL(-1)) significantly enhanced E. coli inactivation in the SS reactor, with 6-log inactivation observed within 90min simulated solar exposure. During the early stages of both SODIS and photocatalytic disinfection, injured E. coli were detected; however, irreversible injury was caused and re-growth was not observed. Experiments under solar conditions were undertaken with total inactivation (6.5-log) observed in the SS reactor within 240min, incomplete inactivation (4-log) was observed in SODIS bottles exposed to the same solar conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Advanced Analysis to Distinguish between Physical Decrease and Inactivation of Viable Phages in Aerosol by Quantitating Phage-Specific Particles.

PubMed

Shimasaki, Noriko; Nojima, Yasuhiro; Sakakibara, Masaya; Kikuno, Ritsuko; Iizuka, Chiori; Okaue, Akira; Okuda, Shunji; Shinohara, Katsuaki

2018-01-01

　Recent studies have investigated the efficacy of air-cleaning products against pathogens in the air. A standard method to evaluate the reduction in airborne viruses caused by an air cleaner has been established using a safe bacteriophage instead of pathogenic viruses; the reduction in airborne viruses is determined by counting the number of viable airborne phages by culture, after operating the air cleaner. The reduction in the number of viable airborne phages could be because of "physical decrease" or "inactivation". Therefore, to understand the mechanism of reduction correctly, an analysis is required to distinguish between physical decrease and inactivation. The purpose of this study was to design an analysis to distinguish between the physical decrease and inactivation of viable phi-X174 phages in aerosols. We established a suitable polymerase chain reaction (PCR) system by selecting an appropriate primer-probe set for PCR and validating the sensitivity, linearity, and specificity of the primer-probe set to robustly quantify phi-X174-specific airborne particles. Using this quantitative PCR system and culture assay, we performed a behavior analysis of the phage aerosol in a small chamber (1 m 3 ) at different levels of humidity, as humidity is known to affect the number of viable airborne phages. The results revealed that the reduction in the number of viable airborne phages was caused not only by physical decrease but also by inactivation under particular levels of humidity. Our study could provide an advanced analysis to differentiate between the physical decrease and inactivation of viable airborne phages.

Effective inactivation of a wide range of viruses by pasteurization.

PubMed

Gröner, Albrecht; Broumis, Connie; Fang, Randel; Nowak, Thomas; Popp, Birgit; Schäfer, Wolfram; Roth, Nathan J

2018-01-01

Careful selection and testing of plasma reduces the risk of blood-borne viruses in the starting material for plasma-derived products. Furthermore, effective measures such as pasteurization at 60°C for 10 hours have been implemented in the manufacturing process of therapeutic plasma proteins such as human albumin, coagulation factors, immunoglobulins, and enzyme inhibitors to inactivate blood-borne viruses of concern. A comprehensive compilation of the virus reduction capacity of pasteurization is presented including the effect of stabilizers used to protect the therapeutic protein from modifications during heat treatment. The virus inactivation kinetics of pasteurization for a broad range of viruses were evaluated in the relevant intermediates from more than 15 different plasma manufacturing processes. Studies were carried out under the routine manufacturing target variables, such as temperature and product-specific stabilizer composition. Additional studies were also performed under robustness conditions, that is, outside production specifications. The data demonstrate that pasteurization inactivates a wide range of enveloped and nonenveloped viruses of diverse physicochemical characteristics. After a maximum of 6 hours' incubation, no residual infectivity could be detected for the majority of enveloped viruses. Effective inactivation of a range of nonenveloped viruses, with the exception of nonhuman parvoviruses, was documented. Pasteurization is a very robust and reliable virus inactivation method with a broad effectiveness against known blood-borne pathogens and emerging or potentially emerging viruses. Pasteurization has proven itself to be a highly effective step, in combination with other complementary safety measures, toward assuring the virus safety of final product. © 2017 The Authors Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.

Effectiveness of Photodynamic Therapy for the Inactivation of Candida spp. on Dentures: In Vitro Study

PubMed Central

Mima, Ewerton Garcia de Oliveira; Ribeiro, Daniela Garcia; Dovigo, Livia Nordi; Vergani, Carlos Eduardo; Bagnato, Vanderlei Salvador

2011-01-01

Abstract Objective: This in vitro study evaluated the effectiveness of photodynamic therapy (PDT) for the inactivation of different species of Candida on maxillary complete dentures. Background data: The treatment of denture stomatitis requires the inactivation of Candida spp. on dentures. PDT has been reported as an effective method for Candida inactivation. Methods: Reference strains of C. albicans, C. glabrata, C. tropicalis, C. dubliniensis and C. krusei were tested. Thirty-four dentures were fabricated in a standardized procedure and subjected to ethylene oxide sterilization. The dentures were individually inoculated with one of the strains and incubated at 37°C for 24 h. Dentures submitted to PDT (P+L+) were individually sprayed with 50 mg/L of Photogem® (PS) and, after 30 min, illuminated by LED light for 26 min (37.5 J/cm2). Additional dentures were treated only with PS (P+L-) or light (P-L+) or neither (P-L-). Samples of serial dilutions were spread on Sabouraud dextrose agar and incubated at 37°C for 48 h. The colonies were counted and the values of log (cfu/mL) were analyzed by Kruskall-Wallis and Dunn tests (p<0.05). Results: For all species of Candida, PDT resulted in significant reduction (p<0.05) of cfu/mL values from dentures when compared with P-L- (reductions from 1.73 to 3.99 log10). Significant differences (p<0.05), but lower reductions, were also observed for P+L- and P-L+when compared with P-L- for some species of Candida. Conclusions: PDT was an effective method for reducing Candida spp. on dentures. PMID:21916614

Predominance of null mutations in ataxia-telangiectasia.

PubMed

Gilad, S; Khosravi, R; Shkedy, D; Uziel, T; Ziv, Y; Savitsky, K; Rotman, G; Smith, S; Chessa, L; Jorgensen, T J; Harnik, R; Frydman, M; Sanal, O; Portnoi, S; Goldwicz, Z; Jaspers, N G; Gatti, R A; Lenoir, G; Lavin, M F; Tatsumi, K; Wegner, R D; Shiloh, Y; Bar-Shira, A

1996-04-01

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.

Blue light induced free radicals from riboflavin on E. coli DNA damage.

PubMed

Liang, Ji-Yuan; Yuann, Jeu-Ming P; Cheng, Chien-Wei; Jian, Hong-Lin; Lin, Chin-Chang; Chen, Liang-Yu

2013-02-05

The micronutrients in many cellular processes, riboflavin (vitamin B(2)), FMN, and FAD are photo-sensitive to UV and visible light to generate reactive oxygen species (ROS). The riboflavin photochemical treatment with UV light has been applied for the inactivation of microorganisms to serve as an effective and safe technology. Ultra-violet or high-intensity radiation is, however, considered as a highly risky practice. This study was working on the application of visible LED lights to riboflavin photochemical reactions to development an effective antimicrobial treatment. The photosensitization of bacterial genome with riboflavin was investigated in vitro and in vivo by light quality and irradiation dosage. The riboflavin photochemical treatment with blue LED light was proved to be able to inactivate E. coli by damaging nucleic acids with ROS generated. Riboflavin is capable of intercalating between the bases of bacterial DNA or RNA and absorbs lights in the visible regions. LED light illumination could be a more accessible and safe practice for riboflavin photochemical treatments to achieve hygienic requirements in vitro. Copyright © 2013 Elsevier B.V. All rights reserved.

Damage tolerance protein Mus81 associates with the FHA1 domain of checkpoint kinase Cds1.

PubMed

Boddy, M N; Lopez-Girona, A; Shanahan, P; Interthal, H; Heyer, W D; Russell, P

2000-12-01

Cds1, a serine/threonine kinase, enforces the S-M checkpoint in the fission yeast Schizosaccharomyces pombe. Cds1 is required for survival of replicational stress caused by agents that stall replication forks, but how Cds1 performs these functions is largely unknown. Here we report that the forkhead-associated-1 (FHA1) protein-docking domain of Cds1 interacts with Mus81, an evolutionarily conserved damage tolerance protein. Mus81 has an endonuclease homology domain found in the XPF nucleotide excision repair protein. Inactivation of mus81 reveals a unique spectrum of phenotypes. Mus81 enables survival of deoxynucleotide triphosphate starvation, UV radiation, and DNA polymerase impairment. Mus81 is essential in the absence of Bloom's syndrome Rqh1 helicase and is required for productive meiosis. Genetic epistasis studies suggest that Mus81 works with recombination enzymes to properly replicate damaged DNA. Inactivation of Mus81 triggers a checkpoint-dependent delay of mitosis. We propose that Mus81 is involved in the recruitment of Cds1 to aberrant DNA structures where Cds1 modulates the activity of damage tolerance enzymes.

Decontamination Efficiency of a DBD Lamp Containing an UV-C Emitting Phosphor.

PubMed

Caillier, Bruno; Caiut, José Maurício Almeida; Muja, Cristina; Demoucron, Julien; Mauricot, Robert; Dexpert-Ghys, Jeanette; Guillot, Philippe

2015-01-01

Among different physical and chemical agents, the UV radiation appears to be an important route for inactivation of resistant microorganisms. The present study introduces a new mercury-free Dielectric Barrier Discharge (DBD) flat lamp, where the biocide action comes from the UV emission produced by rare-earth phosphor obtained by spray pyrolysis, following plasma excitation. In this study, the emission intensity of the prototype lamp is tuned by controlling gas pressure and electrical power, 500 mbar and 15 W, corresponding to optimal conditions. In order to characterize the prototype lamp, the energetic output, temperature increase following lamp ignition and ozone production of the source were measured. The bactericidal experiments carried out showed excellent results for several gram-positive and gram-negative bacterial strains, thus demonstrating the high decontamination efficiency of the DBD flat lamp. Finally, the study of the external morphology of the microorganisms after the exposure to the UV emission suggested that other mechanisms than the bacterial DNA damage could be involved in the inactivation process. © 2015 The American Society of Photobiology.

Cold atmospheric air plasma sterilization against spores and other microorganisms of clinical interest.

PubMed

Klämpfl, Tobias G; Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L; Stolz, Wilhelm; Schlegel, Jürgen; Morfill, Gregor E; Schmidt, Hans-Ulrich

2012-08-01

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log(10) CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D(23)(°)(C) values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma.

Molecular mechanism of plasma sterilization in solution with the reduced pH method: importance of permeation of HOO radicals into the cell membrane

NASA Astrophysics Data System (ADS)

Takai, Eisuke; Ikawa, Satoshi; Kitano, Katsuhisa; Kuwabara, Junpei; Shiraki, Kentaro

2013-07-01

Sterilization of certain infected areas of the human body surface is necessary for dental and surgical therapies. Because the blood is filled with body fluid, sterilization in solution is essential. In vitro solution sterilization has been successively carried out using a combination of low-temperature atmospheric-pressure plasma and the reduced pH method, where the solution is sufficiently acidic. Here, we show the molecular mechanism of such plasma sterilization in solution based on microbiology. Three kinds of bacteria were inactivated by plasma treatment under various pH conditions. The theoretical and experimental models revealed that the sterilization was characterized by the concentration of hydroperoxy radicals (HOO·), which were dependent on the pH value. Bacterial inactivation rates were proportional to the HOO· concentrations calculated by the theoretical model. To evaluate the penetration of radicals into the cell membrane, a bacterial model using dye-included micelles was used. Decolouration rates of the model were also in proportion with the calculated HOO· concentrations. These results indicate that the key species for plasma sterilization were hydroperoxy radicals. More importantly, the high permeation of hydroperoxy radicals into the cell membrane plays a key role for efficient bactericidal inactivation using the reduced pH method.

Cold Atmospheric Air Plasma Sterilization against Spores and Other Microorganisms of Clinical Interest

PubMed Central

Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L.; Stolz, Wilhelm; Schlegel, Jürgen; Morfill, Gregor E.; Schmidt, Hans-Ulrich

2012-01-01

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log10 CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D23°C values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma. PMID:22582068

A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle.

PubMed

van Bolhuis, A I; Holsheimer, J; Savelberg, H H

2001-05-30

Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low intensity and long duration require minimal fatigue. The present study sought to apply a nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle. Two pulse generators were used, independently supplying short supramaximal cathodal stimulating pulses (0.5 ms) and long subthreshold cathodal inactivating pulses (1.5 s) to the sciatic nerve. Propagation of action potentials was selectively blocked in nerve fibres of different diameter by adjusting the strength of the inactivating current. A tensile-testing machine was used to gauge isometric muscle force of the plantaris and both heads of the gastrocnemius muscle. The order of motor-unit recruitment was estimated from twitch characteristics, i.e. peak force and relaxation time. The results showed prolonged relaxation at lower twitch peak forces as the intensity of the inactivating current increased, indicating a reduction of the number of large motor-units to force production. It is shown that the nerve stimulation method described is effective in mimicking physiological muscle control.

The responses of an anaerobic microorganism, Yersinia intermedia MASE-LG-1 to individual and combined simulated Martian stresses

PubMed Central

Bohmeier, Maria; Perras, Alexandra K.; Schwendner, Petra; Rabbow, Elke; Moissl-Eichinger, Christine; Cockell, Charles S.; Pukall, Rüdiger; Vannier, Pauline; Marteinsson, Viggo T.; Monaghan, Euan P.; Ehrenfreund, Pascale; Garcia-Descalzo, Laura; Gómez, Felipe; Malki, Moustafa; Amils, Ricardo; Gaboyer, Frédéric; Westall, Frances; Cabezas, Patricia; Walter, Nicolas; Rettberg, Petra

2017-01-01

The limits of life of aerobic microorganisms are well understood, but the responses of anaerobic microorganisms to individual and combined extreme stressors are less well known. Motivated by an interest in understanding the survivability of anaerobic microorganisms under Martian conditions, we investigated the responses of a new isolate, Yersinia intermedia MASE-LG-1 to individual and combined stresses associated with the Martian surface. This organism belongs to an adaptable and persistent genus of anaerobic microorganisms found in many environments worldwide. The effects of desiccation, low pressure, ionizing radiation, varying temperature, osmotic pressure, and oxidizing chemical compounds were investigated. The strain showed a high tolerance to desiccation, with a decline of survivability by four orders of magnitude during a storage time of 85 days. Exposure to X-rays resulted in dose-dependent inactivation for exposure up to 600 Gy while applied doses above 750 Gy led to complete inactivation. The effects of the combination of desiccation and irradiation were additive and the survivability was influenced by the order in which they were imposed. Ionizing irradiation and subsequent desiccation was more deleterious than vice versa. By contrast, the presence of perchlorates was not found to significantly affect the survival of the Yersinia strain after ionizing radiation. These data show that the organism has the capacity to survive and grow in physical and chemical stresses, imposed individually or in combination that are associated with Martian environment. Eventually it lost its viability showing that many of the most adaptable anaerobic organisms on Earth would be killed on Mars today. PMID:29069099

Combining Lactic Acid Spray with Near-Infrared Radiation Heating To Inactivate Salmonella enterica Serovar Enteritidis on Almond and Pine Nut Kernels

PubMed Central

Ha, Jae-Won

2015-01-01

The aim of this study was to investigate the efficacy of near-infrared radiation (NIR) heating combined with lactic acid (LA) sprays for inactivating Salmonella enterica serovar Enteritidis on almond and pine nut kernels and to elucidate the mechanisms of the lethal effect of the NIR-LA combined treatment. Also, the effect of the combination treatment on product quality was determined. Separately prepared S. Enteritidis phage type (PT) 30 and non-PT 30 S. Enteritidis cocktails were inoculated onto almond and pine nut kernels, respectively, followed by treatments with NIR or 2% LA spray alone, NIR with distilled water spray (NIR-DW), and NIR with 2% LA spray (NIR-LA). Although surface temperatures of nuts treated with NIR were higher than those subjected to NIR-DW or NIR-LA treatment, more S. Enteritidis survived after NIR treatment alone. The effectiveness of NIR-DW and NIR-LA was similar, but significantly more sublethally injured cells were recovered from NIR-DW-treated samples. We confirmed that the enhanced bactericidal effect of the NIR-LA combination may not be attributable to cell membrane damage per se. NIR heat treatment might allow S. Enteritidis cells to become permeable to applied LA solution. The NIR-LA treatment (5 min) did not significantly (P > 0.05) cause changes in the lipid peroxidation parameters, total phenolic contents, color values, moisture contents, and sensory attributes of nut kernels. Given the results of the present study, NIR-LA treatment may be a potential intervention for controlling food-borne pathogens on nut kernel products. PMID:25911473

Intranasal Inactivated Influenza Vaccines: a Reasonable Approach to Improve the Efficacy of Influenza Vaccine?

PubMed

Tamura, Shin-Ichi; Ainai, Akira; Suzuki, Tadaki; Kurata, Takeshi; Hasegawa, Hideki

2016-01-01

Influenza is a contagious, acute respiratory disease caused by the influenza virus. The mucosal lining in the host respiratory tract is not only the site of virus infection, but also the site of defense; it is at this site that the host immune response targets the virus and protects against reinfection. One of the most effective methods to prevent influenza is to induce specific antibody (Ab) responses in the respiratory tract by vaccination. Two types of influenza vaccines, intranasal live attenuated influenza virus (LAIV) vaccines and parenteral (injectable) inactivated vaccines, are currently used worldwide. These vaccines are approved by the European Medicines Agency (EMA) and the US Food and Drug Administration. Live attenuated vaccines induce both secretory IgA (S-IgA) and serum IgG antibodies (Abs), whereas parenteral vaccines induce only serum IgG Abs. However, intranasal administration of inactivated vaccines together with an appropriate adjuvant induces both S-IgA and IgG Abs. Several preclinical studies on adjuvant-combined, nasal-inactivated vaccines revealed that nasal S-IgA Abs, a major immune component in the upper respiratory tract, reacted with homologous virus hemagglutinin (HA) and were highly cross-reactive with viral HA variants, resulting in protection and cross-protection against infection by both homologous and variant viruses, respectively. Serum-derived IgG Abs, which are present mainly in the lower respiratory tract, are less cross-reactive and cross-protective. In addition, our own clinical trials have shown that nasal-inactivated whole virus vaccines, including a built-in adjuvant (single-stranded RNA), induced serum hemagglutination inhibition (HI) Ab titers that fulfilled the EMA criteria for vaccine efficacy. The nasal-inactivated whole virus vaccines also induced high levels of nasal HI and neutralizing Ab titers, although we have not yet evaluated the nasal HI titers due to the lack of official criteria to establish efficacy based on this parameter. Data suggest that adjuvant-combined nasal-inactivated vaccines have advantages over the current injectable vaccine because the former induce both S-IgA and serum IgG Abs. In addition, nasal-inactivated vaccines seem to be superior to the LAIV vaccines, because non-infectious preparations could be used in high-risk groups. Thus, the development of intranasal inactivated vaccines is recommended, because such vaccines are expected to improve the efficacy of influenza vaccines.

Microbial inactivation and cytotoxicity evaluation of UV irradiated coconut water in a novel continuous flow spiral reactor.

PubMed

Bhullar, Manreet Singh; Patras, Ankit; Kilanzo-Nthenge, Agnes; Pokharel, Bharat; Yannam, Sudheer Kumar; Rakariyatham, Kanyasiri; Pan, Che; Xiao, Hang; Sasges, Michael

2018-01-01

A continuous-flow UV reactor operating at 254nm wave-length was used to investigate inactivation of microorganisms including bacteriophage in coconut water, a highly opaque liquid food. UV-C inactivation kinetics of two surrogate viruses (MS2, T1UV) and three bacteria (E. coli ATCC 25922, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115) in buffer and coconut water were investigated (D 10 values ranging from 2.82 to 4.54mJ·cm -2 ). A series of known UV-C doses were delivered to the samples. Inactivation levels of all organisms were linearly proportional to UV-C dose (r 2 >0.97). At the highest dose of 30mJ·cm -2 , the three pathogenic organisms were inactivated by >5 log 10 (p<0.05). Results clearly demonstrated that UV-C irradiation effectively inactivated bacteriophage and pathogenic microbes in coconut water. The inactivation kinetics of microorganisms were best described by log linear model with a low root mean square error (RMSE) and high coefficient of determination (r 2 >0.97). Models for predicting log reduction as a function of UV-C irradiation dose were found to be significant (p<0.05) with low RMSE and high r 2 . The irradiated coconut water showed no cytotoxic effects on normal human intestinal cells and normal mouse liver cells. Overall, these results indicated that UV-C treatment did not generate cytotoxic compounds in the coconut water. This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in coconut water, and suggested potential method for UV-C treatment of other liquid foods. This research paper provides scientific evidence of the potential benefits of UV-C irradiation in inactivating bacterial and viral surrogates at commercially relevant doses of 0-120mJ·cm -2 . The irradiated coconut water showed no cytotoxic effects on normal intestinal and healthy mice liver cells. UV-C irradiation is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier and safe food products. This study would provide technical support for commercialization of UV-C treatment of beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effectiveness of mouse minute virus inactivation by high temperature short time treatment technology: a statistical assessment.

PubMed

Murphy, Marie; Quesada, Guillermo Miro; Chen, Dayue

2011-11-01

Viral contamination of mammalian cell cultures in GMP manufacturing facility represents a serious safety threat to biopharmaceutical industry. Such adverse events usually require facility shutdown for cleaning/decontamination, and thus result in significant loss of production and/or delay of product development. High temperature short time (HTST) treatment of culture media has been considered as an effective method to protect GMP facilities from viral contaminations. Log reduction factor (LRF) has been commonly used to measure the effectiveness of HTST treatment for viral inactivation. However, in order to prevent viral contaminations, HTST treatment must inactivate all infectious viruses (100%) in the medium batch since a single virus is sufficient to cause contamination. Therefore, LRF may not be the most appropriate indicator for measuring the effectiveness of HTST in preventing viral contaminations. We report here the use of the probability to achieve complete (100%) virus inactivation to assess the effectiveness of HTST treatment. By using mouse minute virus (MMV) as a model virus, we have demonstrated that the effectiveness of HTST treatment highly depends upon the level of viral contaminants in addition to treatment temperature and duration. We believe that the statistical method described in this report can provide more accurate information about the power and potential limitation of technologies such as HTST in our shared quest to mitigate the risk of viral contamination in manufacturing facilities. Copyright © 2011 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

Evaluation of some physical and chemical treatments for inactivating microsporidian spores isolated from fish.

PubMed

Leiro, José M; Piazzon, Carla; Domínguez, Berta; Mallo, Natalia; Lamas, Jesús

2012-05-15

Microsporidia are a large diverse group of intracellular parasites now considered as fungi. They are particularly prevalent in fish and are recognized as important opportunistic parasites in humans. Although the mode of transmission of microsporidia has not been fully clarified, the consumption and manipulation of infected fish may be a risk factor for humans. Comparative analysis of rDNA sequence revealed that the microsporidians used in the present study had 99-100% identity with anglerfish microsporidians of the genus Spraguea and very low identity with microsporidians that infect humans. Microsporidian spores were exposed to different physical and chemical treatments: freezing at -20°C for 24-78 h, heating at 60°C for 5-15 min, microwaving at 700 W, 2.45 GHz for 15-60s, and treatment with ethanol at concentrations of between 1 and 70% for 15 min. The viability of the spores after each treatment was evaluated by two methods: a) haemocytometer counts, measuring the extrusion of the polar filament in control and treated spores, and b) a fluorometric method, testing the membrane integrity by propidium iodide exclusion. The results of both methods were concordant. Spores were inactivated by freezing at -20°C for more than 48 h, by heating to 60°C for 10 min and by microwaving at 750 W, for 20s. Exposure to 70% ethanol for 15 min also inactivated microsporidian spores. The results suggest that both freezing and heating are effective treatments for destroying microsporidian spores in European white anglerfish, and that 70% ethanol could be used by fish processors to disinfect their hands and the utensils used in processing fish. The fluorometric method can be used as an alternative to haemocytometer counts in disinfection studies aimed at establishing strategies for inactivating and reducing the viability and the potential infectivity of microsporidians present in fish or in the environment. Copyright © 2012 Elsevier B.V. All rights reserved.

Inactivation of foodborne microorganisms using engineered water nanostructures (EWNS).

PubMed

Pyrgiotakis, Georgios; Vasanthakumar, Archana; Gao, Ya; Eleftheriadou, Mary; Toledo, Eduardo; DeAraujo, Alice; McDevitt, James; Han, Taewon; Mainelis, Gediminas; Mitchell, Ralph; Demokritou, Philip

2015-03-17

Foodborne diseases caused by the consumption of food contaminated with pathogenic microorganisms or their toxins have very serious economic and public health consequences. Here, we explored the effectiveness of a recently developed intervention method for inactivation of microorganisms on fresh produce, and food production surfaces. This method utilizes Engineered Water Nanostructures (EWNS) produced by electrospraying of water vapor. EWNS possess unique properties; they are 25 nm in diameter, remain airborne in indoor conditions for hours, contain Reactive Oxygen Species (ROS) and have very strong surface charge (on average 10 e/structure). Here, their efficacy in inactivating representative foodborne bacteria such as Escherichia coli, Salmonella enterica, and Listeria innocua, on stainless steel surfaces and on organic tomatoes, was assessed. The inactivation was facilitated using two different exposure approaches in order to optimize the delivery of EWNS to bacteria: (1) EWNS were delivered on the surfaces by diffusion and (2) a "draw through" Electrostatic Precipitator Exposure System (EPES) was developed and characterized for EWNS delivery to surfaces. Using the diffusion approach and an EWNS concentration of 24,000 #/cm3, the bacterial concentrations on the surfaces were reduced, depending on the bacterium and the surface type, by values ranging between 0.7 to 1.8 logs. Using the EPES approach and for an aerosol concentration of 50,000 #/cm3 at 90 min of exposure, results show a 1.4 log reduction for E. coli on organic tomato surfaces, as compared to the control (same conditions in regards to temperature and Relative Humidity). Furthermore, for L. innocua, the dose-response relationship was demonstrated and found to be a 0.7 and 1.2 logs removal at 12,000 and 23,000 #/cm3, respectively. The results presented here indicate that this novel, chemical-free, and environmentally friendly intervention method holds potential for development and application in the food industry, as a "green" alternative to existing disinfection methods.

The effect of processing on veterinary residues in foods.

PubMed

Moats, W A

1999-01-01

Heat stability of antibiotics in foods to cooking has been determined by a variety of methods. These include heating in such liquid media as milk, water, buffers and meat extracts, and in solids such as buffered meat homogenates and various sausages. Inactivation of incurred residues in tissues and eggs was also studied. Time and temperature of heating were more easily controlled in liquid media, but results in actual meat products are more indicative of actual cooking processes. Ordinary cooking procedures for meat, even to "well-done", cannot be relied on to inactivate even the more heat sensitive compounds such as penicillins and tetracyclines. More severe heating as for canning or prolonged cooking with moist heat can inactivate the more heat sensitive compounds. The relevance to food safety is uncertain since the nature of the degradation products is unknown in most cases.

Photodynamic inactivation of microorganisms which cause pulmonary diseases with infrared light: an in vitro study

NASA Astrophysics Data System (ADS)

Leite, Ilaiáli S.; Geralde, Mariana C.; Salina, Ana C.; Medeiros, Alexandra I.; Kurachi, Cristina; Bagnato, Vanderlei S.; Inada, Natalia M.

2014-03-01

Lower respiratory infections are among the leading causes of death worldwide. In this study, it was evaluated the interaction of indocyanine green, a photosensitizer activated by infrared light, with alveolar macrophages and the effectiveness of the photodynamic therapy using this compound against Streptococcus pneumoniae . Initial experiments analyzed indocyanine green toxicity to alveolar macrophages in the dark with different drug concentrations and incubation times, and macrophage viability was obtained with the MTT method. The average of the results showed viability values below 90% for the two highest concentrations. Experiments with Streptococcus pneumoniae showed photodynamic inactivation with 10 μM indocyanine green solution. Further experiments with the bacteria in co-culture with AM will be conducted verifying the photodynamic inactivation effectiveness of the tested drug concentrations and incubation periods using infrared light.

A new mode of regulation of N-type inactivation in a Caenorhabditis elegans voltage-gated potassium channel.

PubMed

Cai, Shi-Qing; Sesti, Federico

2007-06-22

N-type inactivation in voltage-gated K+ (Kv) channels is a widespread means to modulate neuronal excitability and signaling. Here we have shown a novel mechanism of N-type inactivation in a Caenorhabditis elegans Kv channel. The N-terminal sequence of KVS-1 contains a domain of 22 amino acids that resembles the inactivation ball in A-type channels, which is preceded by a domain of eighteen amino acids. Wild type KVS-1 currents can be described as A-type; however, their kinetics are significantly (approximately 5-fold) slower. When the putative inactivation ball is deleted, the current becomes non-inactivating. Inactivation is restored in non-inactivating channels by diffusion of the missing inactivation domain in the cytoplasm. Deletion of the domain in front of the ball speeds inactivation kinetics approximately 5-fold. We conclude that KVS-1 is the first example of a novel type of Kv channel simultaneously possessing an N-inactivating ball preceded by an N inactivation regulatory domain (NIRD) that acts to slow down inactivation through steric mechanisms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ying, E-mail: yingliu@doheny.org; Sun Yet-sen University, Zhongshan Ophthalmic Center, State Key Ophthalmic Laboratory, Guangzhou 510060; Kawai, Kirio

Research highlights: {yields} Inactivation of Smad4 caused disruption in the development of the anterior segment. {yields} Inactivation of Smad4 failed to disrupt early lens development. {yields} Smad4 controlled lens cell cycle and cell death processes. {yields} Smad4 may regulate actin stress fiber assembly and eyelid epithelial movement. -- Abstract: Purpose: Signaling by members of the TGF{beta} superfamily of molecules is essential for embryonic development and homeostasis. Smad4, a key intracellular mediator in TGF{beta} signaling, forms transcriptional activator complexes with Activin-, BMP-, and TGF{beta}-restricted Smad proteins. However, the functional role of Smad4 in controlling different visual system compartments has not beenmore » fully investigated. Methods: Using the Pax6 promoter-driven Cre transgenic, smad4 was conditionally inactivated in the lens, cornea and ectoderm of the eyelids. Standard histological and molecular analytical approaches were employed to reveal morphological and cellular changes. Results: Inactivation of Smad4 in the lens led to microphthalmia and cataract formation in addition to the persistent adhesion of the retina to the lens and the iris to the cornea. Inactivation of Smad4 from the ectoderm of the eyelid and cornea caused disruption to eyelid fusion and proper development of the corneal epithelium and corneal stroma. Conclusions: Smad4 is required for the development and maintenance of the lens in addition to the proper development of the cornea, eyelids, and retina.« less

Concentrations and inactivation of Ascaris eggs and pathogen indicator organisms in wastewater stabilization pond sludge.

PubMed

Nelson, K L

2003-01-01

During treatment in wastewater stabilization ponds (WSPs) many pathogens, in particular helminth eggs, are concentrated in the sludge layer. Because periodic removal of the sludge is often required, information is needed on the concentrations and inactivation of pathogens in the sludge layer to evaluate the public health risk they pose upon removal of the sludge. In this paper, previous reports on the sludge concentrations of various pathogen indicator organisms and helminth eggs are reviewed and results from our own recent experiments are reported. The advantages and disadvantages of several methods for studying inactivation in the sludge layer are discussed, as well as implications for the management of WSP sludge. In our recent experiments, which were conducted at three WSPs in central Mexico, sludge cores, dialysis chambers, and batch experiments were used to measure the inactivation rates of fecal coliform bacteria, fecal enterococci, F+ coliphage, somatic coliphage, and Ascaris eggs. The first-order inactivation rate constants were found to be approximately 0.1, 0.1, 0.01, 0.001, and 0.001 d(-1), respectively. The concentrations of all the organisms were found to vary both vertically and horizontally in the sludge layer; therefore, to determine the maximum and average concentration of organisms in the sludge layer of a WSP, complete sludge cores must be collected from representative locations throughout the pond.

Synergistic Effect of Atmospheric-pressure Plasma and TiO2 Photocatalysis on Inactivation of Escherichia coli Cells in Aqueous Media

NASA Astrophysics Data System (ADS)

Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Li, Jiangwei; Wang, Xingquan; Chen, Qiang; Yang, Size; Chen, Zhong; Bazaka, Kateryna; (Ken) Ostrikov, Kostya

2016-12-01

Atmospheric-pressure plasma and TiO2 photocatalysis have been widely investigated separately for the management and reduction of microorganisms in aqueous solutions. In this paper, the two methods were combined in order to achieve a more profound understanding of their interactions in disinfection of water contaminated by Escherichia coli. Under water discharges carried out by microplasma jet arrays can result in a rapid inactivation of E. coli cells. The inactivation efficiency is largely dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2, He and air microplasma arrays, O2 microplasma had the highest activity against E. coli cells in aqueous solution, and showed >99.9% bacterial inactivation efficiency within 4 min. Addition of TiO2 photocatalytic film to the plasma discharge reactor significantly enhanced the inactivation efficiency of the O2 microplasma system, decreasing the time required to achieve 99.9% killing of E. coli cells to 1 min. This may be attributed to the enhancement of ROS generation due to high catalytic activity and stability of the TiO2 photocatalyst in the combined plasma-TiO2 systems. Present work demonstrated the synergistic effect of the two agents, which can be correlated in order to maximize treatment efficiency.

Synergistic Effect of Atmospheric-pressure Plasma and TiO2 Photocatalysis on Inactivation of Escherichia coli Cells in Aqueous Media

PubMed Central

Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Li, Jiangwei; Wang, Xingquan; Chen, Qiang; Yang, Size; Chen, Zhong; Bazaka, Kateryna; (Ken) Ostrikov, Kostya

2016-01-01

Atmospheric-pressure plasma and TiO2 photocatalysis have been widely investigated separately for the management and reduction of microorganisms in aqueous solutions. In this paper, the two methods were combined in order to achieve a more profound understanding of their interactions in disinfection of water contaminated by Escherichia coli. Under water discharges carried out by microplasma jet arrays can result in a rapid inactivation of E. coli cells. The inactivation efficiency is largely dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2, He and air microplasma arrays, O2 microplasma had the highest activity against E. coli cells in aqueous solution, and showed >99.9% bacterial inactivation efficiency within 4 min. Addition of TiO2 photocatalytic film to the plasma discharge reactor significantly enhanced the inactivation efficiency of the O2 microplasma system, decreasing the time required to achieve 99.9% killing of E. coli cells to 1 min. This may be attributed to the enhancement of ROS generation due to high catalytic activity and stability of the TiO2 photocatalyst in the combined plasma-TiO2 systems. Present work demonstrated the synergistic effect of the two agents, which can be correlated in order to maximize treatment efficiency. PMID:28004829

Inactivation of bacteria under visible light and in the dark by Cu films. Advantages of Cu-HIPIMS-sputtered films.

PubMed

Ehiasarian, A; Pulgarin, Cesar; Kiwi, John

2012-11-01

The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods. Direct current magnetron sputtering (DCMS) for 40 s of Cu on cotton inactivated Escherichia coli within 30 min under visible light and within 120 min in the dark. For a longer DCMS time of 180 s, the Cu content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40-s sputtered sample. This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli. Cu DC magnetron sputtering leads to thin metallic semi-transparent gray-brown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP. Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu(2)O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of R (q) and R (a) were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial films.

Inactivating Mutations in NPC1L1 and Protection from Coronary Heart Disease

PubMed Central

2015-01-01

Background Ezetimibe lowers plasma levels of low-density lipoprotein (LDL) cholesterol by inhibiting the activity of the Niemann–Pick C1-like 1 (NPC1L1) protein. However, whether such inhibition reduces the risk of coronary heart disease is not known. Human mutations that inactivate a gene encoding a drug target can mimic the action of an inhibitory drug and thus can be used to infer potential effects of that drug. Methods We sequenced the exons of NPC1L1 in 7364 patients with coronary heart disease and in 14,728 controls without such disease who were of European, African, or South Asian ancestry. We identified carriers of inactivating mutations (nonsense, splice-site, or frameshift mutations). In addition, we genotyped a specific inactivating mutation (p.Arg406X) in 22,590 patients with coronary heart disease and in 68,412 controls. We tested the association between the presence of an inactivating mutation and both plasma lipid levels and the risk of coronary heart disease. Results With sequencing, we identified 15 distinct NPC1L1 inactivating mutations; approximately 1 in every 650 persons was a heterozygous carrier for 1 of these mutations. Heterozygous carriers of NPC1L1 inactivating mutations had a mean LDL cholesterol level that was 12 mg per deciliter (0.31 mmol per liter) lower than that in noncarriers (P = 0.04). Carrier status was associated with a relative reduction of 53% in the risk of coronary heart disease (odds ratio for carriers, 0.47; 95% confidence interval, 0.25 to 0.87; P = 0.008). In total, only 11 of 29,954 patients with coronary heart disease had an inactivating mutation (carrier frequency, 0.04%) in contrast to 71 of 83,140 controls (carrier frequency, 0.09%). Conclusions Naturally occurring mutations that disrupt NPC1L1 function were found to be associated with reduced plasma LDL cholesterol levels and a reduced risk of coronary heart disease. (Funded by the National Institutes of Health and others.) PMID:25390462

Validation of cold plasma treatment for protein inactivation: a surface plasmon resonance-based biosensor study

NASA Astrophysics Data System (ADS)

Bernard, C.; Leduc, A.; Barbeau, J.; Saoudi, B.; Yahia, L'H.; DeCrescenzo, G.

2006-08-01

Gas plasma is being proposed as an interesting and promising tool to achieve sterilization. The efficacy of gas plasma to destroy bacterial spores (the most resistant living microorganisms) has been demonstrated and documented over the last ten years. In addition to causing damage to deoxyribonucleic acid by UV radiation emitted by excited species originating from the plasma, gas plasma has been shown to promote erosion of the microorganism in addition to possible oxidation reactions within the microorganism. In this work, we used lysozyme as a protein model to assess the effect of gas plasma on protein inactivation. Lysozyme samples have been subjected to the flowing afterglow of a gas discharge achieved in a nitrogen-oxygen mixture. The efficiency of this plasma treatment on lysozyme has been tested by two different assays. These are an enzyme-linked immunosorbent assay (ELISA) and a surface plasmon resonance (SPR)-based biosensor assay. The two methods showed that exposure to gas plasma can abrogate lysozyme interactions with lysozyme-specific antibodies, more likely by destroying the epitopes responsible for the interaction. More specifically, two SPR-based assays were developed since our ELISA approach did not allow us to discriminate between background and low, but still intact, quantities of lysozyme epitope after plasma treatment. Our SPR results clearly demonstrated that significant protein destruction or desorption was achieved when amounts of lysozyme less than 12.5 ng had been deposited in polystyrene 96-well ELISA plates. At higher lysozyme amounts, traces of available lysozyme epitopes were detected by SPR through indirect measurements. Finally, we demonstrated that a direct SPR approach in which biosensor-immobilized lysozyme activity is directly measured prior and after plasma treatment is more sensitive, and thus, more appropriate to define plasma treatment efficacy with more certainty.

Methods for targetted mutagenesis in gram-positive bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yunfeng

The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

Inactivation of enveloped and non-enveloped viruses in the process of chemical treatment and gamma irradiation of bovine-derived grafting materials.

PubMed

Lee, Kwang-Il; Lee, Jung-Soo; Jung, Hong-Hee; Lee, Hwa-Yong; Moon, Seong-Hwan; Kang, Kyoung-Tak; Shim, Young-Bock; Jang, Ju-Woong

2012-01-01

Xenografts, unlike other grafting products, cannot be commercialized unless they conform to stringent safety regulations. Particularly with bovine-derived materials, it is essential to remove viruses and inactivate infectious factors because of the possibility that raw materials are imbrued with infectious viruses. The removal of the characteristics of infectious viruses from the bovine bone grafting materials need to be proved and inactivation process should satisfy the management provision of the Food and Drug Administration (FDA). To date, while most virus inactivation studies were performed in human allograft tissues, there have been almost no studies on bovine bone. To evaluate the efficacy of virus inactivation after treatment of bovine bone with 70% ethanol, 4% sodium hydroxide, and gamma irradiation, we selected a variety of experimental model viruses that are known to be associated with bone pathogenesis, including bovine parvovirus (BPV), bovine herpes virus (BHV), bovine viral diarrhea virus (BVDV), and bovine parainfluenza-3 virus (BPIV-3). The cumulative virus log clearance factor or cumulative virus log reduction factor for the manufacturing process was obtained by calculating the sum of the individual virus log clearance factors or log reduction factors determined for individual process steps with different physicochemical methods. The cumulative log clearance factors achieved by three different virus inactivation processes were as follows: BPV ≥ 17.73, BHV ≥ 20.53, BVDV ≥ 19.00, and BPIV-3 ≥ 16.27. On the other hand, the cumulative log reduction factors achieved were as follows: BPV ≥ 16.95, BHV ≥ 20.22, BVDV ≥ 19.27, and BPIV-3 ≥ 15.58. Treatment with 70% ethanol, 4% sodium hydroxide, or gamma irradiation was found to be very effective in virus inactivation, since all viruses were at undetectable levels during each process. We have no doubt that application of this established process to bovine bone graft manufacture will be effective and essential. © 2012 John Wiley & Sons A/S.

Genetic characterization in symptomatic female DMD carriers: lack of relationship between X-inactivation, transcriptional DMD allele balancing and phenotype

PubMed Central

2012-01-01

Background Although Duchenne and Becker muscular dystrophies, X-linked recessive myopathies, predominantly affect males, a clinically significant proportion of females manifesting symptoms have also been reported. They represent an heterogeneous group characterized by variable degrees of muscle weakness and/or cardiac involvement. Though preferential inactivation of the normal X chromosome has long been considered the principal mechanism behind disease manifestation in these females, supporting evidence is controversial. Methods Eighteen females showing a mosaic pattern of dystrophin expression on muscle biopsy were recruited and classified as symptomatic (7) or asymptomatic (11), based on the presence or absence of muscle weakness. The causative DMD gene mutations were identified in all cases, and the X-inactivation pattern was assessed in muscle DNA. Transcriptional analysis in muscles was performed in all females, and relative quantification of wild-type and mutated transcripts was also performed in 9 carriers. Dystrophin protein was quantified by immunoblotting in 2 females. Results The study highlighted a lack of relationship between dystrophic phenotype and X-inactivation pattern in females; skewed X-inactivation was found in 2 out of 6 symptomatic carriers and in 5 out of 11 asymptomatic carriers. All females were characterized by biallelic transcription, but no association was found between X-inactivation pattern and allele transcriptional balancing. Either a prevalence of wild-type transcript or equal proportions of wild-type and mutated RNAs was observed in both symptomatic and asymptomatic females. Moreover, very similar levels of total and wild-type transcripts were identified in the two groups of carriers. Conclusions This is the first study deeply exploring the DMD transcriptional behaviour in a cohort of female carriers. Notably, no relationship between X-inactivation pattern and transcriptional behaviour of DMD gene was observed, suggesting that the two mechanisms are regulated independently. Moreover, neither the total DMD transcript level, nor the relative proportion of the wild-type transcript do correlate with the symptomatic phenotype. PMID:22894145

Evaluation of eco-friendly zwitterionic detergents for enveloped virus inactivation.

PubMed

Conley, Lynn; Tao, Yinying; Henry, Alexis; Koepf, Edward; Cecchini, Douglas; Pieracci, John; Ghose, Sanchayita

2017-04-01

Inclusion of a detergent in protein biotherapeutic purification processes is a simple and very robust method for inactivating enveloped viruses. The detergent Triton X-100 has been used for many years and is part of the production process of several commercial therapeutic proteins. However, recent ecological studies have suggested that Triton X-100 and its break-down products can potentially behave as endocrine disrupters in aquatic organisms, raising concerns from an environmental impact perspective. As such, discharge of Triton X-100 into the waste water treatment plants is regulated in some jurisdictions, and alternative detergents for viral inactivation are required. In this work, we report on the identification and evaluation of more eco-friendly detergents as viable replacements for Triton X-100. Five detergent candidates with low to moderate environmental impact were initially identified and evaluated with respect to protein stability, followed by proof-of-concept virus inactivation studies using a model enveloped virus. From the set of candidates lauryldimethylamine N-oxide (LDAO) was identified as the most promising detergent due to its low ecotoxicity, robust anti-viral activity (LRV >4 at validation set-point conditions with X-MuLX), and absence of any negative impact on protein function. This detergent exhibited effective and robust virus inactivation in a broad range of protein concentrations, solution conductivities, pHs, and in several different cell culture fluid matrices. The only process parameter which correlated with reduced virus inactivation potency was LDAO concentration, and then only when the concentration was reduced to below the detergent's critical micelle concentration (CMC). Additionally, this work also demonstrated that LDAO was cleared to below detectable levels after Protein A affinity chromatography, making it suitable for use in a platform process that utilizes this chromatographic mode for protein capture. All these findings suggest that LDAO may be a practical alternative to Triton X-100 for use in protein therapeutic production processes for inactivating enveloped viruses. Biotechnol. Bioeng. 2017;114: 813-820. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A generalized target theory and its applications.

PubMed

Zhao, Lei; Mi, Dong; Hu, Bei; Sun, Yeqing

2015-09-28

Different radiobiological models have been proposed to estimate the cell-killing effects, which are very important in radiotherapy and radiation risk assessment. However, most applied models have their own scopes of application. In this work, by generalizing the relationship between "hit" and "survival" in traditional target theory with Yager negation operator in Fuzzy mathematics, we propose a generalized target model of radiation-induced cell inactivation that takes into account both cellular repair effects and indirect effects of radiation. The simulation results of the model and the rethinking of "the number of targets in a cell" and "the number of hits per target" suggest that it is only necessary to investigate the generalized single-hit single-target (GSHST) in the present theoretical frame. Analysis shows that the GSHST model can be reduced to the linear quadratic model and multitarget model in the low-dose and high-dose regions, respectively. The fitting results show that the GSHST model agrees well with the usual experimental observations. In addition, the present model can be used to effectively predict cellular repair capacity, radiosensitivity, target size, especially the biologically effective dose for the treatment planning in clinical applications.

Effect of radiation on disinfection and mechanical properties of Korean traditional paper, Hanji

NASA Astrophysics Data System (ADS)

Choi, Jong-il; Chung, Yong Jae; Kang, Dai Ill; Lee, Kyu Shik; Lee, Ju-Woon

2012-08-01

Fumigants, including methyl bromide and ethylene oxide, are generally used for the preservation of the Korean cultural heritage, especially paper products like letters and books. However, the use of fumigants is banned because of their harmful effects on humans and the environment. Gamma irradiation is being considered as an alternative for the sterilization of insects and fungi in organic products. Therefore, the purpose of this study was to investigate the sterilization effects of radiation and its effect on the mechanical properties of the Korean traditional paper—Hanji. Treatment doses of 9 kGy and 8 kGy of gamma irradiation inactivated 5 log units of Aspergillus niger and Bacillus cereus spores inoculated on Hanji, respectively. The gamma irradiations up to an absorbed dose of 50 kGy resulted in no significant changes in the tensile strength, bursting strength, and appearance of Hanji. These results confirmed that radiation treatment disinfects the Korean traditional paper efficiently without changing its properties and that this treatment could be used to prevent the damage of Korean ancient archives by molds and fungi.

Effect of ionizing radiation on the quantitative detection of Salmonella using real-time PCR

NASA Astrophysics Data System (ADS)

Lim, Sangyong; Jung, Jinwoo; Kim, Minjeong; Ryu, Sangryeol; Kim, Dongho

2008-09-01

Food irradiation is an economically viable technology for inactivating foodborne pathogens, but irradiation can mask pathogens in unhygienically prepared food. The aim of this study was to investigate the effect of irradiation treatment on the detection of Salmonella using real-time PCR. Three commercially available kits were tested, of which the InstaGene Matrix procedure was most effective in preparing template DNA from Salmonella exposed to radiation in broth culture. The minimum level of detection by real-time PCR combined with InstaGene Matrix was 3 log units of Salmonella per milliliter. However, when pure cultures of Salmonella were irradiated at 3 and 5 kGy, the cycle threshold ( CT) increased 1-1.5-fold compared to irradiation at 0 and 1 kGy. This indicated that irradiation treatment may result in an underestimation of bacterial counts due to radiation-induced DNA lesions. We also compared CT values in inoculated chicken homogenates before and after irradiation, which in this model caused a 1.3-3.3-fold underestimation of bacterial counts with respect to irradiation dose.

Liquid Water Restricts Habitability in Extreme Deserts

NASA Astrophysics Data System (ADS)

Cockell, Charles S.; Brown, Sarah; Landenmark, Hanna; Samuels, Toby; Siddall, Rebecca; Wadsworth, Jennifer

2017-04-01

Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water.

Poly(ADP-Ribose) Polymerase-1 and DNA-Dependent Protein Kinase Have Equivalent Roles in Double Strand Break Repair Following Ionizing Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Jody; Smith, Graeme; Curtin, Nicola J., E-mail: n.j.curtin@ncl.ac.u

2009-12-01

Purpose: Radiation-induced DNA double strand breaks (DSBs) are predominantly repaired by nonhomologous end joining (NHEJ), involving DNA-dependent protein kinase (DNA-PK). Poly(ADP-ribose) polymerase-1 (PARP-1), well characterized for its role in single strand break repair, may also facilitate DSB repair. We investigated the activation of these enzymes by differing DNA ends and their interaction in the cellular response to ionizing radiation (IR). Methods and Materials: The effect of PARP and DNA-PK inhibitors (KU-0058684 and NU7441) on repair of IR-induced DSBs was investigated in DNA-PK and PARP-1 proficient and deficient cells by measuring gammaH2AX foci and neutral comets. Complementary in vitro enzyme kineticsmore » assays demonstrated the affinities of DNA-PK and PARP-1 for DSBs with varying DNA termini. Results: DNA-PK and PARP-1 both promoted the fast phase of resolution of IR-induced DSBs in cells. Inactivation of both enzymes was not additive, suggesting that PARP-1 and DNA-PK cooperate within the same pathway to promote DSB repair. The affinities of the two enzymes for oligonucleotides with blunt, 3' GGG or 5' GGG overhanging termini were similar and overlapping (K{sub dapp} = 2.6-6.4nM for DNA-PK; 1.7-4.5nM for PARP-1). DNA-PK showed a slightly greater affinity for overhanging DNA and was significantly more efficient when activated by a 5' GGG overhang. PARP-1 had a preference for blunt-ended DNA and required a separate factor for efficient stimulation by a 5' GGG overhang. Conclusion: DNA-PK and PARP-1 are both required in a pathway facilitating the fast phase of DNA DSB repair.« less

Lunar and Planetary Science XXXV: Astrobiology Stew: Pinch of Microbes, Smidgen of UV, Touch of Organics, and Dash of Meteorites

NASA Technical Reports Server (NTRS)

2004-01-01

The session Astrobiology Stew: Pinch of Microbes, Smidgen of UV, Touch of Organics, and Dash of Meteorites includes the following topics: 1) Investigating the Impact of UV Radiation on High-Altitude Shallow Lake Habitats, Life Diversity, and Life Survival Strategies: Clues for Mars' Past Habitability Potential? 2) An Analysis of Potential Photosynthetic Life on Mars; 3) Radiation Inactivation of Bacterial spores on Mars; 4) Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates of Bacteria on Mars Landers; 5) Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents; 6) Signs of Life in Meridiani Planum-What Might Opportunity See (or Miss)? 7) Isolation of PUrines and Pyrimidines from the Murchison Meteorite Using Sublimation; and 8) Relative Amino Acid Composition of CM1 Carbonaceous Chondrites.

Wavelength dependence of biological damage induced by UV radiation on bacteria.

PubMed

Santos, Ana L; Oliveira, Vanessa; Baptista, Inês; Henriques, Isabel; Gomes, Newton C M; Almeida, Adelaide; Correia, António; Cunha, Ângela

2013-01-01

The biological effects of UV radiation of different wavelengths (UVA, UVB and UVC) were assessed in nine bacterial isolates displaying different UV sensitivities. Biological effects (survival and activity) and molecular markers of oxidative stress [DNA strand breakage (DSB), generation of reactive oxygen species (ROS), oxidative damage to proteins and lipids, and the activity of antioxidant enzymes catalase and superoxide dismutase] were quantified and statistically analyzed in order to identify the major determinants of cell inactivation under the different spectral regions. Survival and activity followed a clear wavelength dependence, being highest under UVA and lowest under UVC. The generation of ROS, as well as protein and lipid oxidation, followed the same pattern. DNA damage (DSB) showed the inverse trend. Multiple stepwise regression analysis revealed that survival under UVA, UVB and UVC wavelengths was best explained by DSB, oxidative damage to lipids, and intracellular ROS levels, respectively.

Salmonella internalization in mung bean sprouts and pre- and postharvest intervention methods in a hydroponic system.

PubMed

Ge, Chongtao; Rymut, Susan; Lee, Cheonghoon; Lee, Jiyoung

2014-05-01

Mung bean sprouts, typically consumed raw or minimally cooked, are often contaminated with pathogens. Internalized pathogens pose a high risk because conventional sanitization methods are ineffective for their inactivation. The studies were performed (i) to understand the potential of internalization of Salmonella in mung bean sprouts under conditions where the irrigation water was contaminated and (ii) to determine if pre- and postharvest intervention methods are effective in inactivating the internalized pathogen. Mung bean sprouts were grown hydroponically and exposed to green fluorescence protein-tagged Salmonella Typhimurium through maturity. One experimental set received contaminated water daily, while other sets received contaminated water on a single day at different times. For preharvest intervention, irrigation water was exposed to UV, and for postharvest intervention-contaminated sprouts were subjected to a chlorine wash and UV light. Harvested samples were disinfected with ethanol and AgNO3 to differentiate surface-associate pathogens from the internalized ones. The internalized Salmonella Typhimurium in each set was quantified using the plate count method. Internalized Salmonella Typhimurium was detected at levels of 2.0 to 5.1 log CFU/g under all conditions. Continuous exposure to contaminated water during the entire period generated significantly higher levels of Salmonella Typhimurium internalization than sets receiving contaminated water for only a single day (P < 0.05). Preintervention methods lowered the level of internalized Salmonella by 1.84 log CFU/g (P < 0.05), whereas postintervention methods were ineffective in eliminating internalized pathogens. Preintervention did not completely inactivate bacteria in sprouts and demonstrated that the remaining Salmonella Typhimurium in water became more resistant to UV. Because postharvest intervention methods are ineffective, proper procedures for maintaining clean irrigation water must be followed throughout production in a hydroponic system.

An insight into the photodynamic approach versus copper formulations in the control of Pseudomonas syringae pv. actinidiae in kiwi plants.

PubMed

Jesus, Vânia; Martins, Diana; Branco, Tatiana; Valério, Nádia; Neves, Maria G P M S; Faustino, Maria A F; Reis, Luís; Barreal, Esther; Gallego, Pedro P; Almeida, Adelaide

2018-02-14

In the last decade, the worldwide production of kiwi fruit has been highly affected by Pseudomonas syringae pv. actinidiae (Psa), a phytopathogenic bacterium; this has led to severe economic losses that are seriously affecting the kiwi fruit trade. The available treatments for this disease are still scarce, with the most common involving frequently spraying the orchards with copper derivatives, in particular cuprous oxide (Cu 2 O). However, these copper formulations should be avoided due to their high toxicity; therefore, it is essential to search for new approaches for controlling Psa. Antimicrobial photodynamic therapy (aPDT) may be an alternative approach to inactivate Psa. aPDT consists in the use of a photosensitizer molecule (PS) that absorbs light and by transference of the excess of energy or electrons to molecular oxygen forms highly reactive oxygen species (ROS) that can affect different molecular targets, thus being very unlikely to lead to the development of microbe resistance. The aim of the present study was to evaluate the effectiveness of aPDT to photoinactivate Psa, using the porphyrin Tetra-Py + -Me and different light intensities. The degree of inactivation of Psa was assessed using the PS at 5.0 μM under low irradiance (4.0 mW cm -2 ). Afterward, ex vivo experiments, using artificially contaminated kiwi leaves, were conducted with a PS at 50 μM under 150 mW cm -2 and sunlight irradiation. A reduction of 6 log in the in vitro assays after 90 min of irradiation was observed. In the ex vivo tests, the decrease was lower, approximately 1.8 log reduction at an irradiance of 150 mW cm -2 , 1.2 log at 4.0 mW cm -2 , and 1.5 log under solar radiation. However, after three successive cycles of treatment under 150 mW cm -2 , a 4 log inactivation was achieved. No negative effects were observed on leaves after treatment. Assays using Cu 2 O were also performed at the recommended concentration by law (50 g h L -1 ) and at concentrations 10 times lower, in which at both concentrations, Psa was efficiently inactivated (5 log inactivation) after a few minutes of treatment, but negative effects were observed on the leaves after treatment.

Optimization of PMA-PCR Protocol for Viability Detection of Pathogens

NASA Technical Reports Server (NTRS)

Mikkelson, Brian J.; Lee, Christine M.; Ponce, Adrian

2011-01-01

This presented study demonstrates the need that PMA-PCR can be used to capture the loss of viability of a sample that is much more specific and time-efficient than alternative methods. This protocol is particularly useful in scenarios in which sterilization treatments may inactivate organisms but not degrade their DNA. The use of a PCR-based method of pathogen detection without first inactivating the DNA of nonviable cells will potentially lead to false positives. The loss of culturability, by heat-killing, did not prevent amplified PCR products, which supports the use of PMA to prevent amplification and differentiate between viable and dead cells. PMA was shown to inhibit the amplification of DNA by PCR in vegetative cells that had been heat-killed.

Enhanced citric acid production in aspergillus with inactivated asparagine-linked glycosylation protein 3 (ALG3), and/or increased laeA expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Ziyu; Baker, Scott E.

Provided herein are fungi, such as Aspergillus niger, having a dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase (Alg3) gene genetic inactivation, increased expression of a loss of aflR expression A (Lae), or both. In some examples, such mutants have several phenotypes, including an increased production of citric acid relative to the parental strain. Methods of using the disclosed fungi to make citric acid are also provided, as are compositions and kits including the disclosed fungi.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components. [examined with a scanning electron microscope

NASA Technical Reports Server (NTRS)

Campbell, J. E.

1974-01-01

The uses of scanning electron microscopy in assessing changes that occur in spores exposed to wet and dry heat cycles at elevated temperatures were examined. Several species of Bacillus and other nonspore-forming species of organisms were used for the experiment. Surface morphology of viable and nonviable organisms was clearly detectable by this method, making it a potentially useful technique for investigating microbial inactivation on space vehicle surfaces and components. Micrographs of the spores and bacterial cells are provided.

Flash Inactivation of Oxygen Evolution

PubMed Central

Frasch, Wayne D.; Cheniae, George M.

1980-01-01

Brief saturating light flashes were used to probe the mechanism of inactivation of O2 evolution by Tris in chloroplasts. Maximum inactivation with a single flash and an oscillation with period of four on subsequent flashes was observed. Analyses of the oscillations suggested that only the charge-collecting O2-evolving catalyst of photosystem II (S2-state) was a target of inactivation by Tris. This conclusion was supported by the following observations: (a) hydroxylamine preequilibration caused a three-flash delay in the inactivation pattern; (b) the lifetimes of the Tris-inactivable and S2-states were similar; and (c) reagents accelerating S2 deactivation decreased the lifetime of the inactivable state. Inactivation proved to be moderated by F, the precursor of Signal IIs, as shown by a one flash delay with chloroplasts having high abundance of F. Evidence was obtained for cooperativity effects in inactivation and NH3 was shown to be a competitive inhibitor of the Tris-induced inactivation. S2-dependent inactivation was inhibited by glutaraldehyde fixation of chloroplasts, possibly suggesting that inactivation proceeds via conformational changes of the S2-state. PMID:16661270

Defective Fast Inactivation Recovery of Nav1.4 in Congenital Myasthenic Syndrome

PubMed Central

Arnold, W. David; Feldman, Daniel H.; Ramirez, Sandra; He, Liuyuan; Kassar, Darine; Quick, Adam; Klassen, Tara L.; Lara, Marian; Nguyen, Joanna; Kissel, John T.; Lossin, Christoph; Maselli, Ricardo A.

2015-01-01

Objective To describe the unique phenotype and genetic findings in a 57-year-old female with a rare form of congenital myasthenic syndrome (CMS) associated with longstanding muscle fatigability, and to investigate the underlying pathophysiology. Methods We used whole-cell voltage clamping to compare the biophysical parameters of wild-type and Arg1457His-mutant Nav1.4. Results Clinical and neurophysiological evaluation revealed features consistent with CMS. Sequencing of candidate genes indicated no abnormalities. However, analysis of SCN4A, the gene encoding the skeletal muscle sodium channel Nav1.4, revealed a homozygous mutation predicting an arginine-to-histidine substitution at position 1457 (Arg1457His), which maps to the channel’s voltage sensor, specifically D4/S4. Whole-cell patch clamp studies revealed that the mutant required longer hyperpolarization to recover from fast inactivation, which produced a profound use-dependent current attenuation not seen in the wild type. The mutant channel also had a marked hyperpolarizing shift in its voltage dependence of inactivation as well as slowed inactivation kinetics. Interpretation We conclude that Arg1457His compromises muscle fiber excitability. The mutant fast-inactivates with significantly less depolarization, and it recovers only after extended hyperpolarization. The resulting enhancement in its use dependence reduces channel availability, which explains the patient’s muscle fatigability. Arg1457His offers molecular insight into a rare form of CMS precipitated by sodium channel inactivation defects. Given this channel’s involvement in other muscle disorders such as paramyotonia congenita and hyperkalemic periodic paralysis, our study exemplifies how variations within the same gene can give rise to multiple distinct dysfunctions and phenotypes, revealing residues important in basic channel function. PMID:25707578

Surface water disinfection by chlorination and advanced oxidation processes: Inactivation of an antibiotic resistant E. coli strain and cytotoxicity evaluation.

PubMed

Miranda, Andreza Costa; Lepretti, Marilena; Rizzo, Luigi; Caputo, Ivana; Vaiano, Vincenzo; Sacco, Olga; Lopes, Wilton Silva; Sannino, Diana

2016-06-01

The release of antibiotics into the environment can result in antibiotic resistance (AR) spread, which in turn can seriously affect human health. Antibiotic resistant bacteria have been detected in different aquatic environments used as drinking water source. Water disinfection may be a possible solution to minimize AR spread but conventional processes, such as chlorination, result in the formation of dangerous disinfection by-products. In this study advanced oxidation processes (AOPs), namely H2O2/UV, TiO2/UV and N-TiO2/UV, have been compared with chlorination in the inactivation of an AR Escherichia coli (E. coli) strain in surface water. TiO2 P25 and nitrogen doped TiO2 (N-TiO2), prepared by sol-gel method at two different synthesis temperatures (0 and -20°C), were investigated in heterogeneous photocatalysis experiments. Under the investigated conditions, chlorination (1.0 mg L(-1)) was the faster process (2.5 min) to achieve total inactivation (6 Log). Among AOPs, H2O2/UV resulted in the best inactivation rate: total inactivation (6 Log) was achieved in 45 min treatment. Total inactivation was not observed (4.5 Log), also after 120 min treatment, only for N-doped TiO2 synthesized at 0°C. Moreover, H2O2/UV and chlorination processes were evaluated in terms of cytotoxicity potential by means of 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenylte-trazolium colorimetric test on a human-derived cell line and they similarly affected HepG2 cells viability. Copyright © 2016 Elsevier B.V. All rights reserved.

Method of inactivation of an end product of energy metabolism in Zymomonas mobilis

DOEpatents

Zhang, Min [Lakewood, CO; Chou, Yat-Chen [Lakewood, CO

2008-05-20

The present invention briefly provides a method of site-specific insertion in Zymomonas, comprising, providing a Zymomonas gene fragment, interrupting a DNA sequence the fragment, and transforming the Zymomonas through homologous recombination with the interrupted fragment.

Inactivation of coliphage Q beta by potassium ferrate.

PubMed

Kazama, F

1994-05-15

The kinetics of inactivation of a bacteriophage by potassium ferrate were studied with the F-specific RNA-coliphage Q beta. Inactivation in phosphate buffer (pH 6, 7 and 8) containing ferrate could be described by Hom's model. The inactivation rate depended on the pH. However, the relative effects of ferrate concentration and exposure time on inactivation were not affected by a change in pH from 6 to 8. In a study of the mechanism by which ferrate inactivated the virus, the efficiency of viral inactivation after ferrate decomposed in buffer was assayed. Inactivation was still effective and still followed Hom's equation after the complete decomposition of ferrate ion; however, the efficiency of that inactivation disappeared when sodium thiosulfate was added, suggesting that long-lived oxidative intermediates capable of viral inactivation were generated during the decomposition of ferrate ions.

DIRECT AND INDIRECT BIOLOGICAL EFFECTS OF RADIATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hobitz, H.

1961-01-01

The primary physical processes, ionization and excitation, induced by radiation in biological materials are discussed. Their effects in causing reduction, decarboxylation, and depolymerization in proteins and deoxyribonucleic acid of the cell nucleus are examined. The action of radiation doses of 100,000- 600,000 r on pollen of Digitalis purpurea maintained at room temperature and at approximates 190 deg C showed that biological activity was destroyed by doses >200,000 r at room temperature, but at approximates 190 deg the pollen retained some activity even after the highest dose. A similar effect was seen with Bacterium cadaveris cells, about 0.5% of which survivedmore » 50000 r given at l8O deg whereas no cells survived 20000 r given at 4 deg . The presence of 1% cysteamine at the higher temperature increased survival 20-fold. Cytochrome c showed markedly different responses to radiation in dry form as compared with aqueous solution. The anhydrous enzyme showed a linear decline in log activity with radiation dose but in aqueous solution the activity declined more slowly at higher doses. The radiation dose to-produce 50% inactivation was 4 x 10/sup 7/ r in dry form and 6 x 10/sup 5/ r in solution, a 67-fold difference. The results suggest that diffusion of the free radicals (H: or OH:) produced in the primary process is considerably hindered at low temperature and by the absence of water. (H.H.D.)« less

Wnt Inactivation for Liver Cancer Therapy | Center for Cancer Research

Cancer.gov

Hepatocellular carcinoma (HCC) is the fifth most common and third most deadly type of cancer in the world. The majority of cases occur in Asia and Africa, resulting in most cases being diagnosed only at advanced stages of the disease when drug resistance is high. HCC typically follows damage to the liver such as cirrhosis, making radiation and chemotherapy a more challenging prospect. Surgery is also not a very viable option because less than one in four carcinomas can be completely removed. The limitations in these treatment modalities create the need for alternative therapeutic approaches.

Radiation enhanced reactivation of herpes simplex virus: effect of caffeine.

PubMed

Hellman, K B; Lytle, C D; Bockstahler, L E

1976-09-01

Ultaviolet enhanced (Weigle) reactivation of UV-irradiated herpes simplex virus in UV-irradiated CV-1 monkey kidney cell monolayers was decreased by caffeine. X-ray enhanced reactivation of UV-irradiated virus in X-irradiated monolayers (X-ray reactivation) and UV- or X-ray-inactivated capacity of the cells to support unirradiated virus plaque formation were unaffected by caffeine. The results suggest that a caffeine-sensitive process is necessary for the expression of Weigle reactivation for herpes virus. Since cafeine did not significantly affect X-ray reactivation, different mechanisms may be responsible for the expression of Weigle reactivation and X-ray reactivation.

Role of TGF Beta and PPAR Alpha Signaling Pathways in Radiation Response of Locally Exposed Heart: Integrated Global Transcriptomics and Proteomics Analysis.

PubMed

Subramanian, Vikram; Seemann, Ingar; Merl-Pham, Juliane; Hauck, Stefanie M; Stewart, Fiona A; Atkinson, Michael J; Tapio, Soile; Azimzadeh, Omid

2017-01-06

Epidemiological data from patients undergoing radiotherapy for thoracic tumors clearly show the damaging effect of ionizing radiation on cardiovascular system. The long-term impairment of heart function and structure after local high-dose irradiation is associated with systemic inflammatory response, contraction impairment, microvascular damage, and cardiac fibrosis. The goal of the present study was to investigate molecular mechanisms involved in this process. C57BL/6J mice received a single X-ray dose of 16 Gy given locally to the heart at the age of 8 weeks. Radiation-induced changes in the heart transcriptome and proteome were investigated 40 weeks after the exposure. The omics data were analyzed by bioinformatics tools and validated by immunoblotting. Integrated network analysis of transcriptomics and proteomics data elucidated the signaling pathways that were similarly affected at gene and protein level. Analysis showed induction of transforming growth factor (TGF) beta signaling but inactivation of peroxisome proliferator-activated receptor (PPAR) alpha signaling in irradiated heart. The putative mediator role of mitogen-activated protein kinase cascade linking PPAR alpha and TGF beta signaling was supported by data from immunoblotting and ELISA. This study indicates that both signaling pathways are involved in radiation-induced heart fibrosis, metabolic disordering, and impaired contractility, a pathophysiological condition that is often observed in patients that received high radiation doses in thorax.

Contribution of UVB radiation to bacterial inactivation by natural sunlight.

PubMed

Oppezzo, Oscar J

2012-10-03

The contribution of different components of sunlight to the lethal action exerted by this radiation on bacteria was studied using Pseudomonas aeruginosa ATCC27853 as a model organism. When solar UVB was excluded from the incident radiation by filtering it through a naphthalene solution (cut off 327 nm), significant modifications were observed in the cell-death kinetics. These modifications were comparable to those expected for a reduction of 27-32% in the dose rate, according to the model used in the analysis of the survival curves, and were also observed when the effects of sunlight filtered through polyethylene terephthalate (cut off 331 nm) or polystyrene (cut off 298 nm) were compared. Viability of P. aeruginosa remained almost unchanged when the incident radiation was filtered through a sodium nitrite solution (cut off 406 nm) in order to exclude the UVA and UVB components of sunlight. Nevertheless, a delay in colony formation was detected in bacteria treated in this way, suggesting that a non-lethal effect was exerted by visible light. The results are not consistent with a generally accepted notion which attributes the lethal action of sunlight to the radiation with wavelengths above 320 nm. The characterization of UVB contribution to the lethal effect of sunlight on bacteria is relevant for understanding of the mechanism of cell death, and for improvement of dosimetry techniques and irradiation procedures. Copyright © 2012 Elsevier B.V. All rights reserved.

Inter- and Intra-Chromosomal Aberrations in Human Cells Exposed in vitro to Space-like Radiations

NASA Technical Reports Server (NTRS)

Hada, Megumi; Cucinotta, F. A.; Gonda, S. R.; Wu, H.

2005-01-01

Energetic heavy ions pose a great health risk to astronauts in extended ISS and future exploration missions. High-LET heavy ions are particularly effective in causing various biological effects, including cell inactivation, genetic mutations and cancer induction. Most of these biological endpoints are closely related to chromosomal damage, which can be utilized as a biomarker for radiation insults. Previously, we had studied chromosome aberrations in human lymphocytes and fibroblasts induced by both low- and high-LET radiation using FISH and multicolor fluorescence in situ hybridization (mFISH) techniques. In this study, we exposed human cells in vitro to gamma rays and energetic particles of varying types and energies and dose rates, and analyzed chromosomal damages using the multicolor banding in situ hybridization (mBAND) procedure. Confluent human epithelial cells and lymphocytes were exposed to energetic heavy ions at NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory (Upton, NY) or Cs-137 gamma radiation source at the Baylor College (Houston, TX). After colcemid and Calyculin A treatment, cells were fixed and painted with XCyte3 mBAND kit (MetaSystems) and chromosome aberrations were analyzed with mBAND analysis system (MetaSystems). With this technique, individually painted chromosomal bands on one chromosome allowed the identification of interchromosomal aberrations (translocation to unpainted chromosomes) and intrachromosomal aberrations (inversions and deletions within a single painted chromosome). The possible relationship between the frequency of inter- and intra-chromosomal exchanges and the track structure of radiation is discussed. The work was supported by the NASA Space Radiation Health Program.

Antimicrobial efficacy of irradiation with visible light on oral bacteria in vitro: a systematic review.

PubMed

Pummer, Andreas; Knüttel, Helge; Hiller, Karl-Anton; Buchalla, Wolfgang; Cieplik, Fabian; Maisch, Tim

2017-09-01

Resistances to antibiotics employed for treatment of infectious diseases have increased to alarming numbers making it more and more difficult to treat diseases caused by microorganisms resistant to common antibiotics. Consequently, novel methods for successful inactivation of pathogens are required. In this instance, one alternative could be application of light for treatment of topical infections. Antimicrobial properties of UV light are well documented, but due to its DNA-damaging properties use for medical purposes is limited. In contrast, irradiation with visible light may be more promising. Literature was systematically screened for research concerning inactivation of main oral bacterial species by means of visible light. Inactivation of bacterial species, especially pigmented ones, in planktonic state showed promising results. There is a lack of research examining the situation when organized as biofilms. More research concerning situation in a biofilm state is required.

Evaluation of Combined Peracetic acid and UV treatment for ...

EPA Pesticide Factsheets

The current study evaluates the effectiveness of the combined application of Peracetic acid and ultraviolet radiation as alternative disinfectant agents to the traditional chlorination of wastewater effluents. Various pathogens (E. coli, enterococci and fecal coliforms) were evaluated in the study. Four experiments were conducted using low to high PAA levels and UV dosages. E. coli and enterococci were resistant to low to moderate PAA dosage (0.5- 1 mg/L). These microbes can be removed effectively at high PAA dosage (2.5 mg/L) with 30 min contact time. Fecal coliforms were completely inactivated even at a low PAA dose of 0.7 mg/L. E. coli was more susceptible to UV disinfection than enterococci at low UV dosages. Enterococci required at least 40 mJ/cm2 for 2.5 log inactivation. In combined PAA + UV treatment, low UV intensities between 7 – 40 mJ/cm2 showed poor disinfection performance at a low PAA concentration of 1.5 mg/L. High UV intensities of 120 and 60 mJ/cm2 inactivated all the pathogens to below detection levels even at low to moderate PAA (0.7 mg/L and 1 mg/L) pretreatment concentration. Combined PAA + UV treatment at 1 mg/L (for 15 and 30 min contact time) + 120 and 60 mJ/cm2 did not show any regrowth of microbes, whereas PAA only disinfection with 15 min contact time showed regrowth of enterococci and fecal coliforms. UV only disinfection showed E. coli regrowth. • This pilot scale study was designed for providing necessary parameter optimization

Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in ready-to-bake cookie dough by gamma and electron beam irradiation.

PubMed

Jeong, Seul-Gi; Kang, Dong-Hyun

2017-06-01

This study was conducted to investigate the efficacy of gamma and electron beam irradiation to inactivate foodborne pathogens in ready-to-bake cookie dough and to determine the effect on quality by measuring color and texture changes. Cookie dough inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, or Listeria monocytogenes was subjected to gamma and electron beam irradiation, with doses ranging from 0 to 3 kGy. As the radiation dose increased, the inactivation effect increased among all tested pathogens. After 3.0 kGy of gamma and electron beam irradiation, numbers of inoculated pathogens were reduced to below the detection limit (1 log CFU/g). The D 10 -values of E. coli O157:H7, S. Typhimurium, and L. monocytogenes in cookie dough treated with gamma rays were 0.53, 0.51, and 0.71 kGy, respectively, which were similar to those treated by electron beam with the same dose. Based on the D 10 -value of pathogens in cookie dough, L. monocytogenes showed more resistance to both treatments than did E. coli O157:H7 and S. Typhimurium. Color values and textural characteristics of irradiated cookie dough were not significantly (P > 0.05) different from the control. These results suggest that irradiation can be applied to control pathogens in ready-to-bake cookie dough products without affecting quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

A practical tissue sampling method using ordinary paper for molecular detection of infectious bursal disease virus RNA by RT-PCR.

PubMed

Maw, Min Thein; Yamaguchi, Tsuyoshi; Kasanga, Christopher J; Terasaki, Kaori; Fukushi, Hideto

2006-12-01

A practical sampling method for bursal tissue using ordinary paper for molecular diagnosis of infectious bursal disease (IBD) was established. IBD virus-infected bursa was directly smeared on chromatography paper, filter paper, or stationery copy paper and was then fixed with absolute ethanol, Tris-HCl-saturated phenol, or phenol:chloroform:isoamyl alcohol (25:24:1). Flinders Technology Associates (FTA) card, which is designed for the collection of biological samples for molecular detection, was also used. After storage at 37 C for up to 30 days, total RNA directly extracted from the tissue fixed on the papers and FTA card were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of IBD virus (IBDV) RNA. In addition, the ability of each chemical used in the fixation and the FTA card to inactivate IBDV was evaluated. Regardless of the paper quality, storage period, and fixation method, IBDV RNA was consistently detected in all of the samples. IBDV in the bursal tissue was inactivated with phenol but not with ethanol or the unknown chemicals in FTA card. These results show that ordinary papers sustain the viral RNA, as does FTA card, but phenol fixation is superior to FTA card in inactivating IBDV. The new sampling method using ordinary paper with phenol fixation is safe, inexpensive, simple, and easy, and is thus suitable for conducting a global survey of IBD even where laboratory resources are limited. This practical method should contribute to the control of IBD worldwide.