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Sample records for agar proportion method

  1. Microcolonies in fluoroquinolone agar proportion susceptibility testing of Mycobacterium tuberculosis: an indicator of drug resistance

    PubMed Central

    Blackman, A.; May, S.; Devasia, R. A.; Maruri, F.; Stratton, C.

    2014-01-01

    Microcolony growth of Mycobacterium tuberculosis on agar proportion susceptibility testing is neither well-defined nor previously reported with fluoroquinolone susceptibility testing. We describe here M. tuberculosis microcolony growth with fluoroquinolones, and assess its clinical significance. We screened 797M. tuberculosis isolates for ofloxacin resistance (2.0 µg/mL) by agar proportion; 19 ofloxacin-resistant and 38 ofloxacin-susceptible isolates were selected for more detailed susceptibility testing with ofloxacin, ciprofloxacin, levofloxacin (all at 2.0 µg/mL) and moxifloxacin (0.5 µg/mL). The 57 isolates were also tested at two concentrations both above and below the critical concentrations. Microcolonies were defined as colonies 0.2–0.4 mm in diameter; confirmed microcolonies were present on repeat testing. Of the 57 isolates tested in detail, 7 grew microcolonies, of which 2 (0.3% of all isolates tested) had confirmed microcolonies on repeat testing (6 tests performed, and microcolonies were present on at least 4). Both M. tuberculosis isolates were ofloxacin-resistant on screening, and had ofloxacin minimum inhibitory concentration (MIC) >8 µg/mL. The five other isolates were ofloxacin-susceptible on screening, but had regular colony growth (i.e., resistance) at the drug concentration that initially resulted in microcolonies (ofloxacin 0.5 or 1.0 µg/mL). Microcolonies were observed infrequently with fluoroquinolone susceptibility testing, but when confirmed, they were associated with drug resistance. PMID:22322359

  2. Screening fungicides for use in fish culture: Evaluation of the agar plug transfer, cellophane transfer, and agar dilution methods

    USGS Publications Warehouse

    Bailey, Tom A.

    1983-01-01

    The reliability, reproducibility, and usefulness of three screening methods -- the cellophane transfer, the agar plug transfer, and the agar dilution -- to screen aquatic fungicides were evaluated. Achlya flagellata and Saprolegnia hypogyna were exposed to 1, 10, and 100 mg/L of malachite green to test each method. The cellophane transfer and agar plug transfer techniques had similar reliability and reproducibility in rating fungicidal activity, and were both superior to the agar dilution technique. The agar plug transfer and agar dilution techniques adequately projected in vivo activity of malachite green, but the cellophane transfer technique overestimated its activity. Overall, the agar plug transfer technique most accurately rated the activity of malachite green and was the easiest test to perform. It therefore appears to be the method of choice for testing aquatic fungicides.

  3. Method for Measuring Changes in Surface Tension on Agar

    PubMed Central

    Weisberg, David S.; Dworkin, Martin

    1983-01-01

    The surface tension of agar surfaces was determined by measuring the contact angles formed by drops of various hydrophobic liquids on the surface and then calculating the composite surface free energy function by solving a series of simultaneous equations derived from these data. This method was used to measure the change in the surface tension of agar produced by the addition of various concentrations of albumin. The resulting curve was typical of the effect of increasing concentrations of surfactants on surface tension. The method was compared with other methods of determining surface tension of solids, and it was concluded that the technique used here provided the most reliable results. PMID:16346273

  4. A modified agar plate method for detection of Strongyloides stercoralis.

    PubMed

    Koga, K; Kasuya, S; Khamboonruang, C; Sukhavat, K; Ieda, M; Takatsuka, N; Kita, K; Ohtomo, H

    1991-10-01

    The agar plate method is a new technique with high detection rates for coprological diagnosis of human strongyloidiasis. This report details modifications of the technique and establishes a standardized procedure. We recommend that all plates should be carefully observed using a microscope because macroscopic observation can lead to false negative results. It is also advisable to pour formalin solution directly into microscopically positive dishes to collect worms by sedimentation. This procedure enables one to observe worms otherwise hidden. Sealing dishes with adhesive tape prevents larvae from crawling out of the dishes, eliminating any possibility in the reduction of detection rates, and greatly improves the safety conditions for the technician performing the procedure. We consider the agar plate method to be superior to the filter paper method in detecting Strongyloides, and we believe that it will eventually become the technique of choice. PMID:1951861

  5. Total Antioxidant Capacity of Serum Determined Using the Potassium Permanganate Agar Method Based on Serum Diffusion in Agar

    PubMed Central

    Zhou, Ying; Zhang, Meijuan; Liu, Hui

    2015-01-01

    Objectives. To develop a new method for determining total antioxidants in serum and to evaluate the total antioxidant capacity of organisms. Design and Methods. Sodium hyposulfite (Na2S2O3) and serum were used to evaluate the linearity and precision of the potassium permanganate agar method. The area of serum diffusion in samples from 30 intensive care unit (ICU) patients compared with 44 healthy subjects was determined by the potassium permanganate agar method. Results. The linearity (R2 in the linear experiment of Na2S2O3 was 0.994; R2 in the linear experiment of serum was 0.987) and precision (coefficient of variation of area of high level serum diffusion within-run, between-run, and between-day and coefficient of variation of area of low serum diffusion within-run, between-run, and between-day were all less than 10%) were acceptable using the potassium permanganate agar method. Total antioxidants of serum between the ICU group and the healthy group were different (p = 0.002, two tailed). Conclusions. Total antioxidants in serum can be determined by the potassium permanganate agar method. The total antioxidant capacity of an organism can be evaluated by the amount of total antioxidants in serum. PMID:26347595

  6. Agar underlay method for recovery of sublethally heat-injured bacteria.

    PubMed

    Kang, D H; Siragusa, G R

    1999-12-01

    A method of recovering sublethally heat-injured bacteria was developed. The procedure (termed the agar underlay method) uses a nonselective agar underlaid with a selective medium. In a two-chambered petri dish, the Lutri plate (LP), a nonselective agar is inoculated with a population of sublethally heat-injured bacteria. After a 2-h repair incubation period, selective agar is added to the bottom chamber of the LP and incubated. By diffusing through the nonselective top agar, selective agents from the underlay medium impart selectivity to the system. By the agar underlay method, recovery rates of the heat-injured food-borne pathogens Escherichia coli O157:H7 and Salmonella typhimurium were not different (P > 0. 05) from recovery rates determined with nonselective media. Sublethally heat-injured cells (60 degrees C for 1.5 min in buffer or 80 degrees C for 30 s on meat surfaces) grew and produced a typical colony morphology and color reaction when the agar underlay procedure was used with the appropriate respective selective agars. Unlike agar overlay methods for injury repair, the agar underlay procedure allows the typical selective-medium colony morphology to develop and allows colonies to be more easily picked for further characterization. Higher recovery rates of heat-injured fecal enterococci from bovine fecal samples and total coliforms from animal waste lagoons were obtained by the agar underlay method with selective agars than by direct plating on the respective selective media. PMID:10583985

  7. Reduced turn-around time for Mycobacterium tuberculosis drug susceptibility testing with a proportional agar microplate assay.

    PubMed

    Nguyen, V A T; Nguyen, H Q; Vu, T T; Nguyen, N A T; Duong, C M; Tran, T H T; Nguyen, H V; Dang, D A; Bañuls, A-L

    2015-12-01

    Multidrug-resistant tuberculosis is a major issue worldwide; however, accessibility to drug susceptibility testing (DST) is still limited in developing countries, owing to high costs and complexity. We developed a proportion method on 12-well microplates for DST. The assay reduced the time to results to <12 days and <10 days when bacterial growth was checked with the naked eye or a microscope, respectively. Comparison with the Canetti-Grosset method showed that the results of the two assays almost overlapped (kappa index 0.98 (95% CI 0.91-1.00) for isoniazid, rifampicin, streptomycin; and kappa index 0.92 (95% CI 0.85-0.99) for ethambutol). The sequencing of genes involved in drug resistance showed similar level of phenotype-genotype agreement between techniques. Finally, measurement of the MICs of rifampicin and ethambutol suggests that the currently used critical ethambutol concentration should be revised, and that the current molecular drug susceptibility tests for rifampicin need to be re-evaluated, as in vitro rifampicin-sensitive isolates could harbour drug resistance-associated mutation(s). PMID:26348263

  8. An extension of the Coconut Cream Agar method to screen Penicillium citrinum isolates for citrinin production.

    PubMed

    Mohamed, S; Flint, S; Palmer, J; Fletcher, G C; Pitt, J I

    2013-09-01

    A simple and rapid screening method was developed for the detection of citrinin in fungal cultures using Coconut Cream Agar (CCA) described previously for detecting aflatoxin and ochratoxin A. Fifteen isolates of Penicillium citrinum were inoculated onto CCA and incubated at 25 and 30°C for 10 days. All isolates produced a distinct yellow green fluorescence on CCA when the reverse side of the agar plates were viewed under long wavelength UV light. Detection was optimal at 25°C after four to 5 days of incubation. Isolates positive by the CCA method also tested positive for citrinin production by the TLC agar plug method after growth on CCA, Czapek yeast extract agar and yeast extract sucrose agar. Control cultures were negative by both methods, indicating that the CCA Petri dish method was suitable for screening cultures for citrinin production.

  9. A solid agar overlay method for recovery of heat-injured Listeria monocytogenes.

    PubMed

    Yan, Zhinong; Gurtler, Joshua B; Kornacki, Jeffrey L

    2006-02-01

    A solid agar overlay method was developed for recovery of heat-injured Listeria monocytogenes. Presolidified nonselective tryptic soy agar with 0.6% yeast extract (TSAYE, 2% agar) was overlaid on top of solidified modified Oxford agar (MOX). Heat injury of L. monocytogenes was conducted at 58 degrees C for 6 min in a jacketed flask filled with tryptic soy broth. Both noninjured and heat-treated L. monocytogenes cells were plated onto TSAYE, MOX, and TSAYE-MOX plates. No significant differences (P > 0.05) in recovery were found among the three media for noninjured bacterial cells. Recovery of heat-injured L. monocytogenes cells on TSAYE-MOX overlay plates was equivalent to that on the nonselective TSAYE medium, whereas recovery on the selective MOX medium was significantly lower (P < 0.05) compared with both TSAYE and the overlay plates. There were no significant differences (P > 0.05) among the overlay plates prepared 0, 2, 4, 6, 8, 16, and 24 h prior to plating heat-injured bacterial cells. The TSAYE-MOX overlay also allowed differentiation of L. monocytogenes from a mixture of four other types of foodborne pathogens. This solid agar overlay method for recovery of heat-injured L. monocytogenes cells is less time-consuming and less complicated than the conventional overlay-underlay technique and the double overlay modification of the thin agar layer method and may allow for greater laboratory plating efficiencies.

  10. Efficacy of the thin agar layer method for the recovery of stressed Cronobacter spp. (Enterobacter sakazakii).

    PubMed

    Osaili, Tareq M; Al-Nabulsi, Anas A; Shaker, Reyad R; Al-Holy, Murad M; Al-Haddaq, Mohammed S; Olaimat, Amin N; Ayyash, Mutamed M; Al Ta'ani, Mahmoud K; Forsythe, Stephen J

    2010-10-01

    Cronobacter spp. (Enterobacter sakazakii) are emerging opportunistic pathogens for all age groups, and are of particular concern when it comes to infants. Prior to contaminating food, the organism may be exposed to a variety of stresses, leading to a generation of sublethally injured cells that may not be detected by selective media unless a protracted recovery period is included in the isolation procedure. This study evaluated the efficacy of the thin agar layer (TAL) method for the recovery of Cronobacter cells that had been exposed to various stress conditions. Five strains of C. sakazakii and C. muytjensii were exposed to starvation, heat, cold, acid, alkaline, chlorine, or ethanol, with or without further exposure to desiccation stress. The recovery of the stressed cells was determined on tryptone soy agar (TSA; nonselective control medium), violet red bile glucose agar (VRBGA; selective agar), Druggan-Forsythe-Iversen (DFI; selective agar), and TAL media (viz., VRBGA overlaid with TSA, and DFI overlaid with TSA). Regardless of stress type, there were no significant differences among the recoveries of stressed desiccated Cronobacter spp. cultures on TSA, DFI+TSA, and VRBGA+TSA, but there was significantly less recovery on VRBGA. The recovery of prestressed desiccated Cronobacter spp. on DFI+TSA was similar to that on TSA, whereas the recovery on VRBGA+TSA was lower. DFI+TSA performed better than VRBGA+TSA did in differentiating Cronobacter spp. within mixed bacterial cultures. The results of this study suggest the use of the TAL method DFI+TSA as an improved method for the direct recovery of stressed Cronobacter spp.

  11. Colony morphotype on Sabouraud-triphenyltetrazolium agar: a simple and inexpensive method for Candida subspecies discrimination.

    PubMed Central

    Quindós, G; Fernández-Rodríguez, M; Burgos, A; Tellaetxe, M; Cisterna, R; Pontón, J

    1992-01-01

    A new method of Candida subspecies discrimination on Sabouraud-triphenyltetrazolium agar is reported. Five hundred sixty-two strains of Candida and Torulopsis glabrata, previously identified by conventional mycological methods, were studied. Each strain received a three-letter code and a number based on its colonial morphology. Sixteen morphotypes were found for Candida albicans, 6 were found for Candida parapsilosis, 4 were found for both Candida guilliermondii and Candida krusei, and 12 were found for Candida tropicalis. None of the 56 T. glabrata strains studied grew on this agar. A reproducibility of 95% was found for C. albicans. The simplicity and low cost could make this method useful for typing Candida spp. Images PMID:1400981

  12. Modification of the Congo red agar method to detect biofilm production by Staphylococcus epidermidis.

    PubMed

    Kaiser, Thaís Dias Lemos; Pereira, Eliezer Menezes; Dos Santos, Kátia Regina Netto; Maciel, Ethel Leonor Noia; Schuenck, Ricardo Pinto; Nunes, Ana Paula Ferreira

    2013-03-01

    Staphylococcus epidermidis in immunocompromised patients can cause bacteremia related to the use of catheter due to biofilm production. There are different phenotypic methods to detect biofilm formation. One method is based on culture in brain heart infusion agar (BHIA) containing sucrose and red Congo dye (original Congo red agar). Our group created a new CRA formula and we have confirmed its capacity to detect biofilm production in 210 S. epidermidis strains, including 76 (36.2%) icaAB gene-positive strains. Other parameters were also evaluated. The new CRA formula that gave the best results was BHIA with sucrose (5%), Congo red (0.08%), NaCl (1.5%), glucose (2%), and vancomycin (0.5 mg/mL) (vancomycin-modified CRA-CRAmod). The CRAmod plus vancomycin may be a promising tool and can help to determine the real participation of S. epidermidis in the infectious process.

  13. Modification of the Congo red agar method to detect biofilm production by Staphylococcus epidermidis.

    PubMed

    Kaiser, Thaís Dias Lemos; Pereira, Eliezer Menezes; Dos Santos, Kátia Regina Netto; Maciel, Ethel Leonor Noia; Schuenck, Ricardo Pinto; Nunes, Ana Paula Ferreira

    2013-03-01

    Staphylococcus epidermidis in immunocompromised patients can cause bacteremia related to the use of catheter due to biofilm production. There are different phenotypic methods to detect biofilm formation. One method is based on culture in brain heart infusion agar (BHIA) containing sucrose and red Congo dye (original Congo red agar). Our group created a new CRA formula and we have confirmed its capacity to detect biofilm production in 210 S. epidermidis strains, including 76 (36.2%) icaAB gene-positive strains. Other parameters were also evaluated. The new CRA formula that gave the best results was BHIA with sucrose (5%), Congo red (0.08%), NaCl (1.5%), glucose (2%), and vancomycin (0.5 mg/mL) (vancomycin-modified CRA-CRAmod). The CRAmod plus vancomycin may be a promising tool and can help to determine the real participation of S. epidermidis in the infectious process. PMID:23313084

  14. A modified method for the detection of microbial proteases on agar plates using tannic acid.

    PubMed

    Saran, Saurabh; Isar, Jasmine; Saxena, Rajendra Kumar

    2007-06-10

    In routine assay for the screening of microbes producing proteases, 10% trichloroaceticacid (TCA) is flooded on the milk agar plates after inoculation and required incubation to precipitate the protein. However, the clarity of the hydrolyzed zone is not very sharp and distinct. We herein present an improved assay for detecting the presence of extracellular protease from microorganisms on agar plates. In this method 10% tannic acid is flooded on the milk agar plate (in place of, TCA) to observe the zone of hydrolysis. Tannic acid sharply increases the colour intensity of the plate, as it favours the precipitation of the unhydrolyzed protein in the plate, thereby improving the contrast between the intact zones and the enzymatic lyses zones of the substrate. Our results indicate that this method is useful to detect extracellular proteases produced by both fungi as well as bacteria. The method used in the present study is sensitive, and can be easily performed for screening of large number of microbial cultures. This is the first report on the use of tannic acid for the detection of microbial proteases.

  15. The Resazurin-Agar Method - a Quick Test to Determine Water Quality

    NASA Astrophysics Data System (ADS)

    Huckfeldt, J.; Westphal, B.; Claußen, L.

    2015-12-01

    Rezasurin has been used as a smart tracer in stream ecosystems to indicate metabolic activity, specifically aerobic respiration by heterotrophic bacteria. Resazurin is a blue compound which is irreversibly reduced to the pink resorufin in the presence of aerobic bacteria. The degree and speed of colour change from blue to pink is a measure of the degree of oxygen consumption and thus an indirect indication of the concentration of aerobic bacteria in a given medium. A high concentration of bacteria in water indicates a bad water quality. In our work a method was developed using resazurin agar plates to find a quick and easy way for testing water quality and comparing concentrations of bacteria in freshwater and seawater samples. The theory was to concentrate bacteria from a defined volume of water sample onto polycarbonate filters (0.2 μm), which are then placed onto the resazurin agar plate. The presence of aerobic bacteria on the filter will reduce the resazurin in the agar and the compound changes its colour. First tests conducted with different dilutions of a pure culture of yoghurt bacteria showed promising results and confirmed the feasibility of the method. In a further assay, we used water samples from different water layers and different temperatures and were also able to observe differences in the concentration of bacteria, depending on these different environmental conditions.The assay was also successfully used with seawater samples, collected from 2 different stations at 3 different depths in the Baltic Sea (salinity=15). The discolouration of the plates showed good correlation with the oxygen concentrations in the water. The resazurin-agar plate method is economical and fast. Several samples could be investigated at the same time without sacrificing the reliability of the results. Thus it is a good pre-screening test for a quantitative evaluation of bacteria in a water sample.

  16. A method of test substance removal in agar colony assays using glass capillaries.

    PubMed

    Kastner, M; Maurer, H R

    1984-07-01

    A technique has been developed to remove test substances, after defined incubation periods, from clonogenic in vitro assays using agar-containing glass capillaries. Following removal from the capillaries, the entire agar gels were washed in petri dishes and redrawn into new capillaries. Using 8 radioactive biochemicals of molecular masses ranging from 150 to 1300 dalton the kinetics of diffusion between 1 and 20 min were determined. Using a wash solution-to-assay volume ratio of 20:1, a single washing for 10 min yielded between 90% and 99% removal by diffusion of test substances. By incorporating myelopoietic stem cells it was demonstrated that the cells to be assayed can be quantitatively transferred, without loss or stress, out of and back into capillaries. Thus the reversibility of test substance action can examined under defined conditions avoiding technical problems of previous methods.

  17. An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus.

    PubMed

    Cold, Emma R; Freyria, Nastasia J; Martínez Martínez, Joaquín; Fernández Robledo, José A

    2016-01-01

    The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham's F12-5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham's F12-5% FBS- 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham's F12-5% FBS- 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications.

  18. An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus

    PubMed Central

    Cold, Emma R.; Freyria, Nastasia J.; Martínez Martínez, Joaquín; Fernández Robledo, José A.

    2016-01-01

    The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham’s F12–5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham’s F12–5% FBS– 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham’s F12–5% FBS– 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications. PMID:27149378

  19. An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus.

    PubMed

    Cold, Emma R; Freyria, Nastasia J; Martínez Martínez, Joaquín; Fernández Robledo, José A

    2016-01-01

    The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham's F12-5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham's F12-5% FBS- 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham's F12-5% FBS- 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications. PMID:27149378

  20. AgarTrap: a simplified Agrobacterium-mediated transformation method for sporelings of the liverwort Marchantia polymorpha L.

    PubMed

    Tsuboyama, Shoko; Kodama, Yutaka

    2014-01-01

    The liverwort Marchantia polymorpha L. is being developed as an emerging model plant, and several transformation techniques were recently reported. Examples are biolistic- and Agrobacterium-mediated transformation methods. Here, we report a simplified method for Agrobacterium-mediated transformation of sporelings, and it is termed Agar-utilized Transformation with Pouring Solutions (AgarTrap). The procedure of the AgarTrap was carried out by simply exchanging appropriate solutions in a Petri dish, and completed within a week, successfully yielding sufficient numbers of independent transformants for molecular analysis (e.g. characterization of gene/protein function) in a single experiment. The AgarTrap method will promote future molecular biological study in M. polymorpha.

  1. Evaluation of agar dilution and broth microdilution methods to determine the disinfectant susceptibility.

    PubMed

    Wu, Guoyan; Yang, Qianru; Long, Mei; Guo, Lijuan; Li, Bei; Meng, Yue; Zhang, Anyun; Wang, Hongning; Liu, Shuliang; Zou, Likou

    2015-11-01

    A variety of disinfectants have been widely used in veterinary hygiene, food industries and environments, which could induce the development of bacterial resistance to disinfectants. The methods used to investigate antimicrobial effects of disinfectant vary considerably among studies, making comparisons difficult. In this study, agar dilution and broth microdilution methods were used to compare the antimicrobial activities of four quaternary ammonium compounds (QACs) against foodborne and zoonotic pathogens. The potential relationship between the presence of QACs resistance genes and phenotypic resistance to QACs was also investigated. Our results indicated that the minimum inhibitory concentrations (MICs) determined by two methods might be different depended upon different QACs and bacteria applied. Regardless of the testing methods, Klebsiella pneumoniae was more tolerant among Gram-negative strains to four QACs, followed by Salmonella and Escherichia coli. The agreement between MICs obtained by the two methods was good, for benzalkonium chloride (78.15%), didecyldimethylammonium chloride (DDAC) (82.35%), cetylpyridinium chloride (CTPC) (97.48%) and cetyltrimethylammonium bromide (CTAB) (99.16%), respectively. Among all Gram-negative bacteria, 94.55% (n=52) of qacEΔ1-positive strains showed higher MICs (512 mg l(-1)) to CTAB. The qacEΔ1 gene was highly associated (P<0.05) with the high MICs of QACs (⩾512 mg l(-1)). In addition, DDAC remained as the most effective disinfectant against both Gram-positive and Gram-negative bacteria. This is the first study that compared the agar dilution and broth microdilution methods to assess the antimicrobial activity of QACs. The study demonstrated the need to standardize method that would be used in evaluating QACs antimicrobial properties in the future.

  2. Comparison of the antibacterial activity of chelating agents using the agar diffusion method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine antibacterial activity of 2 metal chelators. Concentrations of 0 to 40 mM of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N,N’-disuccinic acid (EDDS) were prepared in 1.0 M potassium hydroxide (KOH). The pH of the solutions was adjusted to 1...

  3. In vitro antifungal susceptibility testing of Scopulariopsis brevicaulis strains using agar diffusion method.

    PubMed

    Skóra, Magdalena; Macura, Anna B

    2011-01-01

    The genus Scopulariopsis is a common soil saprotroph and has been isolated from air, organic waste and also from plant, animal and human tissues. Scopulariopsis has mainly been associated in humans with superficial mycoses, but it has also been described as the cause of subcutaneous and invasive infections. The most common aetiological agent of infections in humans is Scopulariopsis brevicaulis. This species has been reported to be resistant in vitro to broad-spectrum antifungal agents available today. The aim of the study was to establish in vitro antifungal susceptibility of 35 S. brevicaulis strains against amphotericin B (AMB), flucytosine (FC), caspofungin (CAS), terbinafine (TER), ciclopirox (CIC), voriconazole (VOR), clotrimazole (CTR), miconazole (MCZ), econazole (ECO), ketoconazole (KET), itraconazole (ITR), and fluconazole (FLU). Antifungal susceptibility tests were evaluated by an agar diffusion method (Neo-Sensitabs, Rosco, Denmark). AMB, FC, CAS, ITR and FLU showed no antifungal activity against S. brevicaulis. TER, CIC, CTR, KET, VOR, ECO, and MCZ revealed inhibitory activity for S. brevicaulis, but it varied for each of the drugs. The best antifungal effect was observed for TER and CIC. All isolates had large inhibition zones for TER and CIC. CTR was also inhibitory for all tested S. brevicaulis isolates, but the diameters of inhibition zones were smaller than for TER and CIC. Nearly 89% isolates showed inhibition zones for KET and the mean diameter of the inhibition zone was comparable to CTR. The least antifungal activity exhibited VQR, ECO and MCZ. Because of the multiresistance of S. brevicaulis, infections due to this species may not respond to particular antifungal treatment and other therapeutic approaches should be considered, e.g., combined therapy and/or surgery. PMID:21682097

  4. In vitro antifungal susceptibility testing of Scopulariopsis brevicaulis strains using agar diffusion method.

    PubMed

    Skóra, Magdalena; Macura, Anna B

    2011-01-01

    The genus Scopulariopsis is a common soil saprotroph and has been isolated from air, organic waste and also from plant, animal and human tissues. Scopulariopsis has mainly been associated in humans with superficial mycoses, but it has also been described as the cause of subcutaneous and invasive infections. The most common aetiological agent of infections in humans is Scopulariopsis brevicaulis. This species has been reported to be resistant in vitro to broad-spectrum antifungal agents available today. The aim of the study was to establish in vitro antifungal susceptibility of 35 S. brevicaulis strains against amphotericin B (AMB), flucytosine (FC), caspofungin (CAS), terbinafine (TER), ciclopirox (CIC), voriconazole (VOR), clotrimazole (CTR), miconazole (MCZ), econazole (ECO), ketoconazole (KET), itraconazole (ITR), and fluconazole (FLU). Antifungal susceptibility tests were evaluated by an agar diffusion method (Neo-Sensitabs, Rosco, Denmark). AMB, FC, CAS, ITR and FLU showed no antifungal activity against S. brevicaulis. TER, CIC, CTR, KET, VOR, ECO, and MCZ revealed inhibitory activity for S. brevicaulis, but it varied for each of the drugs. The best antifungal effect was observed for TER and CIC. All isolates had large inhibition zones for TER and CIC. CTR was also inhibitory for all tested S. brevicaulis isolates, but the diameters of inhibition zones were smaller than for TER and CIC. Nearly 89% isolates showed inhibition zones for KET and the mean diameter of the inhibition zone was comparable to CTR. The least antifungal activity exhibited VQR, ECO and MCZ. Because of the multiresistance of S. brevicaulis, infections due to this species may not respond to particular antifungal treatment and other therapeutic approaches should be considered, e.g., combined therapy and/or surgery.

  5. A method for measuring passive elastance during proportional assist ventilation.

    PubMed

    Younes, M; Webster, K; Kun, J; Roberts, D; Masiowski, B

    2001-07-01

    There are currently no reliable, noninvasive ways to monitor respiratory elastance (E) during assisted ventilation. We describe a method that is suited for proportional assist ventilation (PAV). In this mode, the end of the ventilator's inflation phase occurs during the declining phase of inspiratory effort (Pmus). If the opening of the exhalation valve is delayed, airway pressure (Paw) should initially rise as Pmus continues its decline. When Pmus declines to zero, a Paw plateau should appear. Paw at this point should reflect passive recoil at the prevailing volume. A cohort of 74 ventilator-dependent patients, ventilated in the PAV mode, were studied. Brief end-inspiratory occlusions were applied at random intervals. The magnitude of early change in Paw during the occlusion was inversely related to level of assist (r = 0.7, p < 0.00001). At high assist (> 75%), Paw was nearly flat or declined slightly, indicating minimal residual Pmus at the onset of occlusion. At lower assist levels, Paw increased exponentially in most patients with an average time constant of 0.21 +/- 0.06 s. Extraneous events that may corrupt the measurement (e.g., behavioral responses) were extremely rare (< 0.5%) in the first 0.25 s. From these findings, we concluded that Paw measured 0.25 s from occlusion onset (P0.25) includes little inspiratory Pmus and is free of extraneous events. E, estimated from P0.25 during PAV (EPAV), agreed well (r = 0.92) with passive E measured during controlled ventilation (ECMV); the average difference (EPAV - ECMV) was (+/- SD) -0.3 +/- 4.9 cm H2O x L(-1), corresponding to 0.9 +/- 16.4% of average E. We conclude that Paw measured at 0.25 s from the onset of end-inspiratory occlusion in the PAV mode provides a reliable estimate of passive elastic recoil.

  6. Improved method of screening for aflatoxin with a coconut agar medium.

    PubMed

    Davis, N D; Iyer, S K; Diener, U L

    1987-07-01

    Nine isolates of Aspergillus flavus and Aspergillus parasiticus were screened for aflatoxin production on a coconut extract agar medium. Aflatoxin-producing colonies were detected under long-wave UV light (365 nm) by blue fluorescence on the reverse side after 2 to 5 days of growth. Aflatoxin production was verified by chemical analysis. Several types of shredded coconut available in the United States were tested and found to be satisfactory. No additives were required. Various parameters affecting the test were investigated.

  7. Comparison of E-test with agar dilution methods in testing susceptibility of N. gonorrhoeae to azithromycin.

    PubMed

    Yasin, R M; Suan, K A; Meng, C Y

    1997-05-01

    A single dose of a new antibiotic, azithromycin, has been shown to be effective in the treatment of uncomplicated Neisseria gonorrhoeae. A clinical study was conducted to assess the in vitro susceptibility of N gonorrhoeae to azithromycin and compare the reliability of results obtained using the new E-test methodology for determination of the minimum inhibitory concentration (MIC) of antibiotic with those obtained through the standard agar dilution method. 135 clinical isolates of N gonorrhoeae were obtained from patients attending hospital-based sexually transmitted disease clinics in five geographic locations in Malaysia. 76 of the isolates were penicillinase-producing N gonorrhoeae and 69 were high-level tetracycline-resistant N gonorrhoeae. All isolates were susceptible to azithromycin based on the susceptible MIC breakpoint of 2.0 mcg/ml. The MICs ranged from 0.0078-0.25 mcg/ml by agar dilution method and from 0.016-0.50 mcg/ml by E-test. Agreement between these two methods was 97.8%. The single-dose regime and good antigonococcal and antichlamydial activity of azithromycin make this antibiotic a suitable treatment choice. Moreover, the findings of this study suggest that the simpler, faster E-test is as reliable as the agar dilution method. Given the tendency of the antimicrobial susceptibility pattern of N gonorrhoeae to change rapidly, it is important to monitor MICs to detect the emergence of resistance.

  8. Evaluation of PCR-based screening for vancomycin-resistant enterococci compared with a chromogenic agar-based culture method.

    PubMed

    Seo, Ja Young; Kim, Pyung-Whan; Lee, Jang-Ho; Song, Jae-Hoon; Peck, Kyong-Ran; Chung, Doo-Ryeon; Kang, Cheol-In; Ki, Chang-Seok; Lee, Nam Yong

    2011-07-01

    Rapid detection of vancomycin-resistant enterococci (VRE) infection is very important for control and prevention of nosocomial spread of these bacteria. A multiplex PCR method for rapid screening of VRE has recently been developed. We performed a prospective study of VRE screening tests to compare the performance of PCR to that of a chromogenic agar-based culture method. From January to December 2009, a total of 8815 rectal swab specimens were tested simultaneously for VRE by VRE selective culture and by PCR. The specimens were inoculated onto ChromID VRE agar containing 8 µg vancomycin ml⁻¹ and examined after 24 and 48 h of incubation. Identification and antibiotic susceptibility tests were performed using the automated VITEK-2 system and a supplementary E-test and disk diffusion test. Detection of the vanA and vanB genes was performed with the Seeplex VRE detection kit. Specimens were inoculated in enterococcosel broth for 16-24 h before PCR for enrichment of VRE. VRE were isolated from 741 of the 8815 specimens by chromogenic agar-based culture (8.4 %). vanA and vanB genotypes were detected in 758 (8.6 %) and 3 (0.03 %) specimens, respectively, by multiplex PCR. Sensitivity, specificity, positive predictive value and negative predictive value of PCR for detection of VRE were 98.2 %, 99.6 %, 95.7 %, and 99.8 %. No VRE were isolated from vanB-positive specimens. The overall performance of PCR is comparable to that of a chromogenic agar-based culture method for screening of VRE, so PCR could be an alternative or supportive method for effective control of nosocomial VRE infection.

  9. Agar block smear preparation: a novel method of slide preparation for preservation of native fungal structures for microscopic examination and long-term storage.

    PubMed

    Woo, Patrick C Y; Ngan, Antonio H Y; Chui, Hon-Kit; Lau, Susanna K P; Yuen, Kwok-Yung

    2010-09-01

    We describe a novel method of fungal slide preparation named "agar block smear preparation." A total of 510 agar block smears of 25 fungal strains obtained from culture collections, 90 QC fungal strains, and 82 clinical fungal strains from our clinical microbiology laboratory, which included a total of 137 species of yeasts, molds, and thermal dimorphic fungi, were prepared and examined. In contrast to adhesive tape preparation, agar block smears preserved the native fungal structures, such as intact conidiophores of Aspergillus species and arrangements of conidia in Scopulariopsis brevicaulis. Furthermore, agar block smears allowed examination of fungal structures embedded in the agar, such as the ascomata with ascomal hairs in Chaetomium funicola; pycnidium of Phoma glomerata; the intercalary ovoidal chlamydospores arranged in chains of Fusarium dimerum; and the lateral, spherical chlamydospores arranged in pairs of Fusarium solani. After 1 year of storage, morphological integrity was found to have been maintained in 459 (90%) of the 510 agar block smears. After 3 years of storage, morphological integrity was found to have been maintained in 72 (71%) of the 102 smears prepared in 2006. Agar block smear preparation preserves the native fungal structures and allows long-term storage and examination of fungal structures embedded in the agar, hence overcoming the major drawbacks of adhesive tape preparation. The major roles of agar block smear should be diagnosis for difficult cases, accurate identification of fungal species for clinical management of patients and epidemiological studies, and long-term storage for transportation of slides and education purposes.

  10. Detection of intermediately vancomycin-susceptible and heterogeneous Staphylococcus aureus isolates: comparison of Etest and Agar screening methods.

    PubMed

    Riederer, K; Shemes, S; Chase, P; Musta, A; Mar, A; Khatib, R

    2011-06-01

    Detection of Staphylococcus aureus isolates with intermediate vancomycin susceptibility (VISA) and heteroresistance (hVISA) remains problematic. The population analysis profile/area under the curve (PAP/AUC) is the gold standard but is cumbersome. We compared the performance of two Etest screening methods (macromethod [MAC] and glycopeptide resistance detection [GRD]) plus brain heart infusion (BHI) agars supplemented with 3 (BHI-V3) or 4 (BHI-V4) mg/liter vancomycin in detecting hVISA and/or VISA phenotypes. Etest hVISA screenings were done in parallel for 485 saved methicillin-resistant S. aureus (MRSA) blood isolates according to the manufacturer's instructions. The PAP/AUC was measured for all isolates according to the modified method. PAP/AUC test isolate/Mu3 ratios of <0.9, 0.9 to 1.3, and >1.3 were considered positive for susceptible MRSA (S-MRSA), hVISA, and VISA, respectively. PAP/AUC revealed seven VISA and 33 hVISA phenotypes. MAC screening was positive for 30 (75.0%) hVISA/VISA and 49 (11.0%) S-MRSA isolates. GRD screening was positive for 28 (70.0%) hVISA/VISA and 63 (14.2%) S-MRSA isolates. Growth on BHI-V3 was noted in all hVISA/VISA and 24 (5.4%) S-MRSA isolates. Growth on BHI-V4 was noted in all VISA and four (12.1%) hVISA isolates. None of the S-MRSA isolates grew on BHI-V4 agar. The sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were 75.0%, 89.0%, 38.0%, and 97.5% for MAC; 70.0%, 85.8%, 30.8%, and 97.0% for GRD; 100%, 94.6%, 62.5%, and 100% for BHI-V3; and 100, 99.2%, 63.6%, and 100% for BHI-V4 (for detecting VISA). These findings suggest that both Etest screening methods have excellent NPV, but positive results require confirmation. BHI-V3 and BHI-V4 agars provide more precise identification of hVISA and VISA, respectively; they may be reasonable alternatives to PAP/AUC.

  11. The agar diffusion scratch assay - A novel method to assess the bioactive and cytotoxic potential of new materials and compounds

    PubMed Central

    Pusnik, Mascha; Imeri, Minire; Deppierraz, Grégoire; Bruinink, Arie; Zinn, Manfred

    2016-01-01

    A profound in vitro evaluation not only of the cytotoxic but also of bioactive potential of a given compound or material is crucial for predicting potential effects in the in vivo situation. However, most of the current methods have weaknesses in either the quantitative or qualitative assessment of cytotoxicity and/or bioactivity of the test compound. Here we describe a novel assay combining the ISO 10993-5 agar diffusion test and the scratch also termed wound healing assay. In contrast to these original tests this assay is able to detect and distinguish between cytotoxic, cell migration modifying and cytotoxic plus cell migration modifying compounds, and this at higher sensitivity and in a quantitative way. PMID:26861591

  12. Rapid Direct Testing of Susceptibility of Mycobacterium tuberculosis to Isoniazid and Rifampin on Nutrient and Blood Agar in Resource-Starved Settings

    PubMed Central

    Ikram, Aamer; Coban, Ahmet Yilmaz; Martin, Anandi

    2012-01-01

    In this study, we evaluated the performance of blood agar (by macroscopic growth) and nutrient agar (by a microcolony detection method) for drug susceptibility testing of Mycobacterium tuberculosis against rifampin (RIF) and isoniazid (INH), using 67 smear-positive sputum specimens. The direct proportion method on Lowenstein-Jensen (LJ) medium was used as the “gold standard.” Compared with LJ medium, results for both media were in 100% agreement for RIF, while for INH the agreement levels for blood agar and nutrient agar were 98% and 95%, respectively. Within 2 weeks, 100% of specimens yielded results on blood agar, while 96.8% of specimens yielded results on nutrient agar. Our study showed that blood agar and nutrient agar can be used as alternative media for direct susceptibility testing of RIF and INH, especially in resource-poor settings. PMID:22357498

  13. Rapid direct testing of susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin on nutrient and blood agar in resource-starved settings.

    PubMed

    Satti, Luqman; Ikram, Aamer; Coban, Ahmet Yilmaz; Martin, Anandi

    2012-05-01

    In this study, we evaluated the performance of blood agar (by macroscopic growth) and nutrient agar (by a microcolony detection method) for drug susceptibility testing of Mycobacterium tuberculosis against rifampin (RIF) and isoniazid (INH), using 67 smear-positive sputum specimens. The direct proportion method on Lowenstein-Jensen (LJ) medium was used as the "gold standard." Compared with LJ medium, results for both media were in 100% agreement for RIF, while for INH the agreement levels for blood agar and nutrient agar were 98% and 95%, respectively. Within 2 weeks, 100% of specimens yielded results on blood agar, while 96.8% of specimens yielded results on nutrient agar. Our study showed that blood agar and nutrient agar can be used as alternative media for direct susceptibility testing of RIF and INH, especially in resource-poor settings.

  14. The antibacterial activity of sodium hypochlorite and chlorhexidine against Enterococcus faecalis: A review on agar diffusion and direct contact methods

    PubMed Central

    Luddin, Norhayati; Ahmed, Hany Mohamed Aly

    2013-01-01

    Complete debridement and disinfection of the root canal system are fundamental requirements for successful endodontic treatment. Despite the morphological challenges of the internal root anatomy, root canal irrigants play an important role in the optimization of the root canal preparation, which is essentially a chemo-mechanical procedure. Enterococcus faecalis is one of the most resistant microorganisms that dominants the microbial ecosystem of persistent periradicular lesions in retreatment cases. For that reason, many in vitro and in vivo studies evaluated and compared the antibacterial activity of sodium hypochlorite and chlorhexidine at varying concentrations using different experimental models against this microorganism. However, many controversies with regard to the ideal irrigant and concentration do in fact exist. Hence, this review aims to discuss the antibacterial activity of these two main root canal irrigants against Enterococcus faecalis using the agar diffusion and direct contact methods and the possible modulating factors responsible for inconsistent findings among different studies. In addition, the disinfection potential of both chemical agents on gutta percha and Resilon cones are also discussed. The source of this review was conducted through an electronic literature search using PubMed database from December 1997 until December 2011, which analyze the related laboratory investigations of both irrigants, published in major endodontic journals. PMID:23349569

  15. [Assessment of 2 automated microdilution techniques compared to an agar dilution method in determining sensitivity to fosfomycin in strains of carbapenem-resistant Pseudomonas aeruginosa].

    PubMed

    Gil-Romero, Yolanda; Regodón-Domínguez, Marta; Wilhelmi de Cal, Isabel; López-Fabal, Fátima; Gómez-Garcés, José Luis

    2016-01-01

    Carbapenems-resistance in Pseudomonas aeruginosa isolates has been widely reported. Fosfomycin has been shown to act synergistically with other antimicrobials. The agar dilution method was approved for susceptibility testing for fosfomycin and Pseudomonas aeruginosa. However, broth microdilution methods are the basis of systems currently used in clinical microbiology laboratories. The results of this study indicate that these methods are acceptable as susceptibility testing methods for fosfomycin against these organisms.

  16. Evaluation of agar-based medium with sheep sera for testing of drug susceptibility of Mycobacterium tuberculosis to Isoniazid, Rifampin, Ethambutol, and Streptomycin.

    PubMed

    Coban, Ahmet Yilmaz; Uzun, Meltem; Bozdogan, Bulent

    2013-12-01

    The performance of sheep sera instead of sheep blood in agar-based media was investigated for susceptibility testing of Mycobacterium tuberculosis against primary drugs. The levels of agreement between agar-based medium supplemented with sheep sera and the proportion method on Middlebrook 7H11 agar as the reference method for determining susceptibility to isoniazid (INH), rifampin (RIF), ethambutol (EMB), and streptomycin (STR) were 98.4, 98.4, 95.3, and 100%, respectively.

  17. Comparative evaluation of a chromogenic agar medium-PCR protocol with a conventional method for isolation of Vibrio parahaemolyticus strains from environmental and clinical samples.

    PubMed

    Canizalez-Roman, Adrian; Flores-Villaseñor, Héctor; Zazueta-Beltran, Jorge; Muro-Amador, Secundino; León-Sicairos, Nidia

    2011-02-01

    Screening for pathogenic Vibrio parahaemolyticus has become routine in certain areas associated with food-borne outbreaks. This study is an evaluation of the CHROMagar Vibrio (CV) medium-PCR protocol and the conventional method (TCBS (thiosulfate-citrate-bile salts-sucrose) agar plus biochemical and Wagatsuma agar tests) for detection of V. parahaemolyticus in shrimp, water, sediment, and stool samples collected for biosurveillance in an endemic area of northwestern Mexico. A total of 131 environmental and clinical samples were evaluated. The CV medium-PCR protocol showed a significantly improved ability (P < 0.05) to isolate and detect V. parahaemolyticus, identifying isolates of this bacteria missed by the conventional method. Although some other bacteria, distinct from pathogenic V. parahaemolyticus, produced violet colonies similar to that of V. parahaemolyticus on CV medium, we were able to detect a superior number of samples of V. parahaemolyticus with the CV medium-PCR protocol than with the conventional method. The Kanagawa phenomenon is routinely determined on Wagatsuma agar for the diagnosis of V. parahaemolyticus (pathogenic) positive for thermostable direct hemolysin (TDH) in developing countries. In our results, Wagatsuma agar showed low sensitivity (65.4% at 24 h and 75.6% at 48 h) and specificity (52.4% at 48 h) for identifying V. parahaemolyticus positive for TDH. Overall, our data support the use of the CV medium-PCR protocol in place of the conventional method (TCBS-biochemical tests-Wagatsuma agar) for detection of pathogenic V. parahaemolyticus, both in terms of effectiveness and cost efficiency.

  18. Comparison of Results Obtained by Testing with Three Different Agar Media and by the NCCLS M27-A Method for In Vitro Testing of Fluconazole against Candida spp.

    PubMed Central

    Rubio, M. Carmen; Gil, Joaquina; de Ocáriz, Inmaculada Ramírez; Benito, Rafael; Rezusta, Antonio

    2003-01-01

    Fluconazole susceptibilities of 150 Candida isolates were determined by a 25-μg fluconazole disk diffusion agar test and compared with the microdilution NCCLS M27-A method. The agar test used three different media and was read at 24 and 48 h. When only the susceptible and nonsusceptible categories were used, disk diffusion with Müeller-Hinton agar supplemented with 2% glucose and 0.5 μg of methylene blue (MHGM) per ml had a 95.37% correlation with the MIC method at 24 h, followed by RPMI 1640-2% of glucose agar (correlation, 94%) and Shadomy medium (SHDM) (correlation, 92.6%). The growth of microcolonies inside the inhibition zones was common (>63%) in the RPMI and SHDM media and minimal with MHGM (8.7%). At 48 h, MHGM and SHDM still had a >91% correlation with the MIC, while RPMI results had dropped to 75%. The best overall agreement was obtained with C. dubliniensis (100%). PMID:12791899

  19. [An observation on the histological structure of Oncomelania hupensis soft tissue by agar-paraffin double-embedding method].

    PubMed

    Tan, Ping; Zhang, Jie; Li, Qing; Yu, Zhi-jun

    2014-12-01

    In order to study the histological structure of Oncomelania hupensis soft tissue, the fixed soft tissues of O. hupensis were pre-embedded in the agar and made blocks, then dehydrated, transparentized, immersed in paraffin, sectioned, and stained with haematoxylin-eosin (HE). Permanent slides of O. hupensis soft tissue were obtained. The histological structure of soft tissues was clear under the microscope.

  20. 21 CFR 582.7115 - Agar-agar.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Agar-agar. 582.7115 Section 582.7115 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7115 Agar-agar. (a) Product. Agar-agar. (b) Conditions of use. This substance is generally recognized as safe when used...

  1. 21 CFR 582.7115 - Agar-agar.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Agar-agar. 582.7115 Section 582.7115 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7115 Agar-agar. (a) Product. Agar-agar. (b) Conditions of use. This substance is generally recognized as safe when used...

  2. Comparison of a novel MPN method against the yeast extract agar (YEA) pour plate method for the enumeration of heterotrophic bacteria from drinking water.

    PubMed

    Sartory, David P; Gu, Haoyi; Chen, Chun-Ming

    2008-07-01

    This study compared the Quanti-Disc most probable number (MPN) test for heterotrophic bacteria from drinking water with the widely used yeast extract agar (YEA) pour plate method. The Quanti-Disc test module contains 50 reaction wells in which a medium has been pre-deposited. The medium contains a suite of three fluorogenic enzyme substrates selected for the detection of enzymes expressed widely by heterotrophic bacteria. The MPN of heterotrophic bacteria is calculated from the number of fluorescing reaction wells after incubation of a sample. Quanti-Disc and the YEA pour plate method were compared according to guidance on comparing methods given in United Kingdom national guidance and ISO 17994:2004. The two methods were also challenged with reference strains and isolates of heterotrophic bacteria from drinking water. This indicated that heterotrophic bacteria commonly encountered in drinking water are detected by both the YEA pour plate method and Quanti-Disc. Analysis of data from split water samples (723 for 37 degrees C tests and 872 for 22 degrees C tests) from nine geographically diverse laboratories in England and Wales demonstrated that the Quanti-Disc method is equivalent to the YEA pour plate method for the analysis of heterotrophic bacteria from drinking and similar waters at 37 degrees C, and superior to YEA for the analysis at 22 degrees C. The Quanti-Disc method is a simple and efficient alternative method for the enumeration of heterotrophic bacteria from drinking water.

  3. Comparison of Sorbitol MacConkey Agar and a Two-Step Method Which Utilizes Enzyme-Linked Immunosorbent Assay Toxin Testing and a Chromogenic Agar To Detect and Isolate Enterohemorrhagic Escherichia coli

    PubMed Central

    Novicki, Thomas J.; Daly, Judy A.; Mottice, Susan L.; Carroll, Karen C.

    2000-01-01

    Enterohemorrhagic Escherichia coli (EHEC) and specifically serotype O157:H7 are a significant cause of hemorrhagic gastrointestinal disease and the hemolytic uremic syndrome. Methods currently used in clinical microbiology labs, such as sorbitol-MacConkey (SMAC) agar, reliably detect only O157:H7. We have evaluated a two-step method that has the potential to identify and isolate all EHEC serotypes, including serotype O157:H7. This method utilizes a chromogenic selective-differential medium for the isolation of E. coli together with an enzyme-linked immunosorbent assay (ELISA) that detects the Shiga-like toxins Stx1 and Stx2. Both are commercially available and usable in a wide range of clinical microbiology laboratories. Compared to a Vero cell cytotoxic assay, SMAC had sensitivities of 23.5% for the identification of all EHEC serotypes and of 50.0% for the identification of O157:H7 alone. The two-step method had sensitivities of 76.5 and 100%, respectively. The ELISA alone had a sensitivity of 82.4% in the detection of Stx1 and Stx2. The specificity was 100% in all cases. Overall, 14 EHEC isolates were obtained: 8 (58%) O157:H7, 2 (14%) O26, 2 (14%) O111:NM, 1 (7%) O103:H2, and 1 (7%) O121:H19. All but one were isolated during the months of May to September. The two-step method was found to be considerably more expensive than SMAC for both positive and negative samples. PMID:10655343

  4. A practical petrological method for the determination of volume proportions of magma chamber refilling

    NASA Astrophysics Data System (ADS)

    Bindeman, Ilya N.

    1993-05-01

    A method is described for determining the proportion of the volume of a magma chamber refilled by new pulses of hot primitive melts. This method is based on the changes is crystal contents and in phenocryst zoning resulting from temperature equilibration. Study of phenocryst zoning and the composition of interstitial glasses from various chilled magmatic inclusions and mafic bands in hybrid rocks supports the idea that equilibration of temperatures between two magmas is reached before their physical mixing. If the magmas are genetically related (for example magma-fractionate and initial hot melt), this leads to equilibration of the compositions of residual melts and phenocrysts rims. Intervals of reverse zoning in minerals, resulting from temperature increases, and intervals of normal zoning, caused by cooling, along with the changes in modal mineral contents enable estimation of the amounts of released and adsorbed heat and, therefore, assessment of the proportion of the volume of each magma. Application of the method to some hybrid volcanic series of the Kurile-Kamchatka island arc shows that the proportion of mafic magma intruded into a siliceous magma chamber reservoir never exceeds 10% of the volume of the host magma, based upon thermal considerations. However, the observed degree of compositional mingling requres 25-50% of the mafic end-member. It is shown that this contradiction is related to flotation of vesiculated magmatic inclusions towards the chamber roof, where they become concentrated near the exit and are further mingled with the host during the eruption (forced convection).

  5. Parameter tuning method for dither compensation of a pneumatic proportional valve with friction

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Song, Yang; Huang, Leisheng; Fan, Wei

    2016-05-01

    In the practical application of pneumatic control devices, the nonlinearity of a pneumatic control valve become the main factor affecting the control effect, which comes mainly from the dynamic friction force. The dynamic friction inside the valve may cause hysteresis and a dead zone. In this paper, a dither compensation mechanism is proposed to reduce negative effects on the basis of analyzing the mechanism of friction force. The specific dither signal (using a sinusoidal signal) was superimposed on the control signal of the valve. Based on the relationship between the parameters of the dither signal and the inherent characteristics of the proportional servo valve, a parameter tuning method was proposed, which uses a displacement sensor to measure the maximum static friction inside the valve. According to the experimental results, the proper amplitude ranges are determined for different pressures. In order to get the optimal parameters of the dither signal, some dither compensation experiments have been carried out on different signal amplitude and gas pressure conditions. Optimal parameters are determined under two kinds of pressure conditions. Using tuning parameters the valve spool displacement experiment has been taken. From the experiment results, hysteresis of the proportional servo valve is significantly reduced. And through simulation and experiments, the cut-off frequency of the proportional valve has also been widened. Therefore after adding the dither signal, the static and dynamic characteristics of the proportional valve are both improved to a certain degree. This research proposes a parameter tuning method of dither signal, and the validity of the method is verified experimentally.

  6. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1115 Agar-agar. (a) Agar-agar (CAS Reg. No. PM 9002-18-0) is a...

  7. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1115 Agar-agar. (a) Agar-agar (CAS Reg. No. PM 9002-18-0) is a...

  8. Blood agar validation for susceptibility testing of isoniazid, rifampicin, ethambutol, and streptomycin to Mycobacterium tuberculosis isolates.

    PubMed

    Coban, Ahmet Yilmaz

    2013-01-01

    In recent studies, it was shown that blood agar can be used at least as effectively as Löwenstein-Jensen medium for growing Mycobacterium tuberculosis. It was also shown that susceptibility testing can be performed on blood agar. Additional validation of blood agar was performed on regional M. tuberculosis isolates from Turkey to determine critical concentrations of isoniazid (INH), rifampicin (RIF), ethambutol (ETM), and streptomycin (STR). In the current study, 40 M. tuberculosis clinical isolates were tested. H37Rv, which is susceptible to all antituberculosis agents, ATCC 35822 (INH-resistant), ATCC 35838 (RIF-resistant), ATCC 35837 (ETM-resistant), and ATCC 35820 (STR-resistant) quality control strains were used as control strains. Proportion method on 7H11 agar was considered as gold standard in the study. MIC values of the control strains and clinical isolates were detected on blood and 7H11 agar. Categorical agreements were 100% for each antibiotic, and essential agreements were 100%, 97.5%, 82.5%, and 95% for INH, RIF, ETM, and STR, respectively. According to the data, 0.2 µg/mL for INH, 1 µg/mL for RIF, 4 µg/mL for ETM, and 2 µg/mL for STR were appropriate breakpoint values for susceptibility testing on blood agar. Blood agar may be recommended for use in both developed and developing countries for the susceptibility testing of M. tuberculosis isolates to primary antituberculosis drugs.

  9. Bacteria holding times for fecal coliform by mFC agar method and total coliform and Escherichia coli by Colilert®-18 Quanti-Tray® method

    USGS Publications Warehouse

    Aulenbach, Brent T.

    2010-01-01

    Bacteria holding-time experiments of up to 62 h were performed on five surface-water samples from four urban stream sites in the vicinity of Atlanta, GA, USA that had relatively high densities of coliform bacteria (Escherichia coli densities were all well above the US Environmental Protection Agency criterion of 126 colonies (100 ml) − 1 for recreational waters). Holding-time experiments were done for fecal coliform using the membrane filtration modified fecal coliform (mFC) agar method and for total coliform and E. coli using the Colilert®-18 Quanti-Tray® method. The precisions of these analytical methods were quantified. Precisions determined for fecal coliform indicated that the upper bound of the ideal range of counts could reasonably be extended upward and would improve precision. For the Colilert®-18 method, analytical precisions were similar to the theoretical precisions for this method. Fecal and total coliform densities did not change significantly with holding times up to about 27 h. Limited information indicated that fecal coliform densities might be stable for holding times of up to 62 h, whereas total coliform densities might not be stable for holding times greater than about 27 h. E. coli densities were stable for holding times of up to 18 h—a shorter period than indicated from a previous studies. These results should be applicable to non-regulatory monitoring sampling designs for similar urban surface-water sample types.

  10. Absolute determination of radiation bursts and of proportional counters space charge effect through the influence method

    NASA Astrophysics Data System (ADS)

    Rios, I. J.; Mayer, R. E.

    2016-11-01

    When proportional counters are employed in charge integration mode to determine the magnitude of a radiation pulse, so intense that individual detection events take place in a time too short to produce individual output pulses, mostly in pulsed neutron sources, the strong build-up of positive space charge reduces the electric multiplication factor of the proportional detector. Under such conditions the ensuing measurement underestimates the amount of radiation that interacted with the detector. If the geometric characteristics, the filling gas pressure and the voltage applied to that detector are known, it becomes possible to apply an analytical correction method to the measurement. In this article we present a method that allows to determine the absolute value of the detected radiation burst without the need to know the characteristics of the employed detectors. It is necessary to employ more than one detector, taking advantage of the Influence Method. The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency and without the need to register coincidences of any kind. This method exploits the influence of the presence of one detector in the count rate of another detector, when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency (Rios and Mayer, 2015 [1,2]). Its practical implementation in the measurement of a moderated neutron flux arising from an isotopic neutron source was exemplified in (Rios and Mayer, 2016 [3]) and the extension for multiple detectors in (Rios and Mayer 2016 [4]).

  11. New method of proportional counter feedback biasing for wide-range radiation dose-rate monitors

    SciTech Connect

    Kopp, M.K.; Gueerant, G.C.; Manning, F.W.; Valentine, K.H.

    1985-02-01

    A prototypic wide-range radiation dose-rate monitor for civil defense applications has been developed and tested. The specified dose-rate range (0 to 500 R/h) was displayed on a single readout scale by using feedback-controlled biasing of a proportional counter. This new method is based on controlling the avalanche multiplication factor (gas gain) of the counter by varying its bias voltage in response to its measured output current (i.e., detected dose rate). The counter output current varies between 0 and 1.5 nA in a quasilogarithmic response to dose rates between 0 and 500 R/h. The corresponding values of gas gain and bias voltage range from 1 to 300 and 200 to 1900 V respectively.

  12. New method of proportional counter feedback biasing for wide-range radiation dose-rate monitors

    SciTech Connect

    Kopp, M.K.; Valentine, K.H.; Guerrant, G.C.; Manning, F.W.

    1984-01-01

    A prototypic wide-range radiation dose-rate monitor for civil defense applications has been developed and tested. The specified dose-rate range (0 to 500 R/h) was displayed on a single readout scale by using feedback-controlled biasing of a proportional counter. This new method is based on controlling the avalanche multiplication factor (gas gain) of the counter by varying its bias voltage in response to its measured output current (i.e., detected dose rate). The counter output current varies between 0 and 1.5 nA in a quasi-logarithmic response to dose rates between 0 and 500 R/h. The corresponding values of gas gain and bias voltage range from 1 to 300 and 200 to 1900 V respectively.

  13. Proportion of Pelvic Inflammatory Disease Cases Caused by Chlamydia trachomatis: Consistent Picture From Different Methods

    PubMed Central

    Price, Malcolm J.; Ades, A. E.; Welton, Nicky J.; Simms, Ian; Macleod, John; Horner, Paddy J.

    2016-01-01

    Background. Pelvic inflammatory disease (PID) is a leading cause of both tubal factor infertility and ectopic pregnancy. Chlamydia trachomatis is an important risk factor for PID, but the proportion of PID cases caused by C. trachomatis is unclear. Estimates of this are required to evaluate control measures. Methods. We consider 5 separate methods of estimating age-group-specific population excess fractions (PEFs) of PID due to C. trachomatis, using routine data, surveys, case-control studies, and randomized controlled trials, and apply these to data from the United Kingdom before introduction of the National Chlamydia Screening Programme. Results. As they are informed by randomized comparisons and national exposure and outcome estimates, our preferred estimates of the proportion of PID cases caused by C. trachomatis are 35% (95% credible interval [CrI], 11%–69%) in women aged 16–24 years and 20% (95% CrI, 6%–38%) in women aged 16–44 years in the United Kingdom. There is a fair degree of consistency between adjusted estimates of PEF, but all have wide 95% CrIs. The PEF decreases from 53.5% (95% CrI, 15.6%–100%) in women aged 16–19 years to 11.5% (95% CrI, 3.0%–25.7%) in women aged 35–44 years. Conclusions. The PEFs of PID due to C. trachomatis decline steeply with age by a factor of around 5-fold between younger and older women. Further studies of the etiology of PID in different age groups are required. PMID:27260786

  14. Standardized methods and quality control limits for agar and broth microdilution susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum.

    PubMed

    Waites, Ken B; Duffy, Lynn B; Bébéar, Cécile M; Matlow, Anne; Talkington, Deborah F; Kenny, George E; Totten, Patricia A; Bade, Donald J; Zheng, Xiaotian; Davidson, Maureen K; Shortridge, Virginia D; Watts, Jeffrey L; Brown, Steven D

    2012-11-01

    An international multilaboratory collaborative study was conducted to develop standard media and consensus methods for the performance and quality control of antimicrobial susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum using broth microdilution and agar dilution techniques. A reference strain from the American Type Culture Collection was designated for each species, which was to be used for quality control purposes. Repeat testing of replicate samples of each reference strain by participating laboratories utilizing both methods and different lots of media enabled a 3- to 4-dilution MIC range to be established for drugs in several different classes, including tetracyclines, macrolides, ketolides, lincosamides, and fluoroquinolones. This represents the first multilaboratory collaboration to standardize susceptibility testing methods and to designate quality control parameters to ensure accurate and reliable assay results for mycoplasmas and ureaplasmas that infect humans.

  15. Comparison of recovery of airborne microorganisms in a dairy cattle facility using selective agar and thin agar layer resuscitation media.

    PubMed

    Crozier-Dodson, Beth Ann; Fung, Daniel Y C

    2002-09-01

    Thin agar layer (TAL) medium was developed at Kansas State University to improve the resuscitation of injured cells and has been shown to result in higher recovery than is obtained with selective media alone for cold-, heat-, salt-, and acid-injured cells. The experiment presented here was designed to determine the effectiveness of the TAL method for the recovery of possibly injured organisms from air. Eleven agar media were used for the experiment: tryptic soy agar (TSA), MacConkey sorbitol agar (MSA), TAL-MSA, Baird-Parker (BP) agar, TAL-BP agar, modified Oxford (MOX) agar, TAL-MOX agar, xylose lysine sodium desoxycholate (XLD) agar, TAL-XLD agar, Yersinia-selective (CIN) agar, and TAL-CIN agar. The TAL plates were prepared by pipetting 6 ml of selective agar into a BBL Rodac plate (65 by 15 mm). Selective agar was allowed to solidify, and then each plate was overlaid with 6 ml of TSA. Selective agar plates were prepared by pipetting 12 ml of agar into BBL Rodac plates and allowing the agar to solidify. Samples were taken at an indoor cattle facility at five separate locations with a BioScience SAS air-sampling instrument. For each plate, 60 liters of air was sampled. Three replications of the experiment were performed. The TAL method resulted in higher counts of microorganisms on all media tested. In addition, 175 isolates were selected randomly and identified in order to test the selectivity of TAL and the selective media for target organisms. The data obtained in this study show that the TAL resuscitation method is effective and necessary for the recovery of airborne organisms that may be injured.

  16. Evaluation of an automated agar plate streaker.

    PubMed Central

    Tilton, R C; Ryan, R W

    1978-01-01

    An automated agar plate streaker was evaluated. The Autostreaker mechanizes the agar plate streaking process by providing storage for plates, labeling and streaking one or more plates for either isolation or quantitation, and stacking in one of several racks for subsequent incubation. Results showed the Autostreaker to produce agar plates with well-separated colonies and accurate colony counts. A total of 1,930 clinical specimens were processed either in parallel with manual methods or solely by the Autostreaker. Technologist acceptance of machine-streaked plates was outstanding. Images PMID:348722

  17. A comparison of several methods for the confidence intervals of negative binomial proportions

    NASA Astrophysics Data System (ADS)

    Thong, Alfred Lim Sheng; Shan, Fam Pei

    2015-12-01

    This study focuses on the comparison of the performances of several approaches in constructing confidence interval of negative binomial proportions (single negative binomial proportion and the difference between two negative binomial proportions). After that, the strengths and weaknesses of the approaches in constructing confidence interval of negative binomial proportions are figured out. Performances of the approaches will be accessed by comparing their coverage probabilities and average lengths of confidence intervals. For the comparison of the performances of the approaches in single negative binomial proportion, Wald confidence interval (WCI-I), Agresti confidence interval (ACI-I), Wilson's Score confidence interval (WSCI-I) and Jeffrey confidence interval (JCI-I) are used. WSCI-I is the better approach for single negative binomial proportion in term of the average length of confidence intervals and average coverage probability. While for the comparison of the performances of the approaches in the difference between two negative binomial proportions, Wald confidence interval (WCI-II), Agresti confidence interval (ACI-II), Newcombe's Score confidence interval (NSCI-II), Jeffrey confidence interval (JCI-II) and Yule confidence interval (YCI-II) are used. Under different situations, a better approach has been discussed and recommended. There will be different approach that performs better for the coverage probability.

  18. A Flexible, Computationally Efficient Method for Fitting the Proportional Hazards Model to Interval-Censored Data

    PubMed Central

    Wang, Lianming; Hudgens, Michael G.; Qureshi, Zaina P.

    2015-01-01

    Summary The proportional hazards model (PH) is currently the most popular regression model for analyzing time-to-event data. Despite its popularity, the analysis of interval-censored data under the PH model can be challenging using many available techniques. This paper presents a new method for analyzing interval-censored data under the PH model. The proposed approach uses a monotone spline representation to approximate the unknown nondecreasing cumulative baseline hazard function. Formulating the PH model in this fashion results in a finite number of parameters to estimate while maintaining substantial modeling flexibility. A novel expectation-maximization (EM) algorithm is developed for finding the maximum likelihood estimates of the parameters. The derivation of the EM algorithm relies on a two-stage data augmentation involving latent Poisson random variables. The resulting algorithm is easy to implement, robust to initialization, enjoys quick convergence, and provides closed-form variance estimates. The performance of the proposed regression methodology is evaluated through a simulation study, and is further illustrated using data from a large population-based randomized trial designed and sponsored by the United States National Cancer Institute. PMID:26393917

  19. Syneresis in agar hydrogels.

    PubMed

    Boral, Shilpi; Saxena, Anita; Bohidar, H B

    2010-03-01

    Agar hydrogels exhibit syneresis which creates internal osmotic stress on the physical network. It was observed that such a stress gives rise to characteristic pulsating modes (breathing modes). Experiments carried over a period of 60-day revealed that the network deformations grew monotonously when the solvent released by syneresis was removed periodically from gel surface. However, when the solvent was not withdrawn, the gel exhibited very slowly relaxing breathing modes. The swelling-deswelling dynamics has been discussed in the generalized framework of a dissipative damped oscillator.

  20. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  1. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  2. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD... ingredient meets the specifications of the “Food Chemicals Codex,” 3d Ed. (1981), p. 11, which...

  3. Enumeration of sublethally injured Escherichia coli O157:H7 ATCC 43895 and Escherichia coli strain B-41560 using selective agar overlays versus commercial methods.

    PubMed

    Smith, Amanda R; Ellison, Alysha L; Robinson, Amanda L; Drake, Maryanne; McDowell, Susan A; Mitchell, James K; Gerard, Patrick D; Heckler, Rachel A; McKillip, John L

    2013-04-01

    Quality control procedures during food processing may involve direct inoculation of food samples onto appropriate selective media for subsequent enumeration. However, sublethally injured bacteria often fail to grow, enabling them to evade detection and intervention measures and ultimately threaten the health of consumers. This study compares traditional selective and nonselective agar-based overlays versus two commercial systems (Petrifilm and Easygel) for recovery of injured E. coli B-41560 and O157:H7 strains. Bacteria were propagated in tryptic soy broth (TSB), ground beef slurry, and infant milk formula to a density of 10(6) to 10(8) CFU/ml and then were stressed for 6 min either in lactic acid (pH 4.5) or heat shocked for 3 min at 60°C. Samples were pour plated in basal layers of either tryptic soy agar (TSA), sorbitol MacConkey agar (SMAC), or violet red bile agar (VRB) and were resuscitated for 4 h prior to addition of agar overlays. Other stressed bacteria were plated directly onto Petrifilm and Easygel. Results indicate that selective and nonselective agar overlays recovered significantly higher numbers (greater than 1 log) of acid- and heat-injured E. coli O157:H7 from TSB, ground beef, and infant milk formula compared with direct plating onto selective media, Petrifilm, or Easygel, while no significant differences among these media combinations were observed for stressed E. coli B-41560. Nonstressed bacteria from TSB and ground beef were also recovered at densities significantly higher in nonselective TSA-TSA and in VRB-VRB and SMAC-SMAC compared with Petrifilm and Easygel. These data underscore the need to implement food safety measures that address sublethally injured pathogens such as E. coli O157:H7 in order to avoid underestimation of true densities for target pathogens.

  4. Comparative evaluation of the VITEK 2, disk diffusion, etest, broth microdilution, and agar dilution susceptibility testing methods for colistin in clinical isolates, including heteroresistant Enterobacter cloacae and Acinetobacter baumannii strains.

    PubMed

    Lo-Ten-Foe, Jerome R; de Smet, Anne Marie G A; Diederen, Bram M W; Kluytmans, Jan A J W; van Keulen, Peter H J

    2007-10-01

    Increasing antibiotic resistance in gram-negative bacteria has recently renewed interest in colistin as a therapeutic option. The increasing use of colistin necessitates the availability of rapid and reliable methods for colistin susceptibility testing. We compared seven methods of colistin susceptibility testing (disk diffusion, agar dilution on Mueller-Hinton [MH] and Isosensitest agar, Etest on MH and Isosensitest agar, broth microdilution, and VITEK 2) on 102 clinical isolates collected from patient materials during a selective digestive decontamination or selective oral decontamination trial in an intensive-care unit. Disk diffusion is an unreliable method to measure susceptibility to colistin. High error rates and low levels of reproducibility were observed in the disk diffusion test. The colistin Etest, agar dilution, and the VITEK 2 showed a high level of agreement with the broth microdilution reference method. Heteroresistance for colistin was observed in six Enterobacter cloacae isolates and in one Acinetobacter baumannii isolate. This is the first report of heteroresistance to colistin in E. cloacae isolates. Resistance to colistin in these isolates seemed to be induced upon exposure to colistin rather than being caused by stable mutations. Heteroresistant isolates could be detected in the broth microdilution, agar dilution, Etest, or disk diffusion test. The VITEK 2 displayed low sensitivity in the detection of heteroresistant subpopulations of E. cloacae. The VITEK 2 colistin susceptibility test can therefore be considered to be a reliable tool to determine susceptibility to colistin in isolates of genera that are known not to exhibit resistant subpopulations. In isolates of genera known to (occasionally) exhibit heteroresistance, an alternative susceptibility testing method capable of detecting heteroresistance should be used.

  5. A comparison of a new centrifuge sugar flotation technique with the agar method for the extraction of immature Culicoides (Diptera: Ceratopogonidae) life stages from salt marsh soils.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two sampling techniques, agar extraction (AE) and centrifuge sugar flotation extraction (CSFE) were compared to determine their relative efficacy to recover immature stages of Culicoides spp from salt marsh substrates. Three types of samples (seeded with known numbers of larvae, homogenized field s...

  6. Impact of estrous synchronization methods on cellular proportions in cervical mucus and serum hormone concentrations.

    PubMed

    Ahmadi, M R; Nazifi, S; Sajedianfard, J; Moattari, G

    2007-02-01

    The objective of this study was to examine cytological changes of cervical mucus following the induction of estrus with intra-vaginal drug release (CIDR) devices in dairy cows. Sixty healthy Holstein Frisian cows, averaging 80 (+/-10) days post-partum, were selected from a commercial dairy farm around Shiraz. Cows in the control group were synchronized by the Ovsynch protocol. Cows in the second group (OV+CIDR) were subjected to the same Ovsynch protocol but in addition were administered a progesterone-releasing CIDR. Cows in the third group (OV+S-CIDR) were subjected to Ovsynch procedures but received the skeleton of a CIDR device, which did not release progesterone. Cows in the fourth group (E2+CIDR) received a progesterone releasing CIDR but were injected with estradiol benzoate. Cows in group 5 (E2+S-CIDR) received a CIDR skeleton and estrodial benzoate. CIDR devices were removed from cows in groups 2-4 and all cows were injected with PGF2alpha on day -3. Blood samples and cervical mucus discharges were collected from all cows on days -10, -3, 0 and 12 relative to AI. On the day of AI, the mean+/-S.D. percentage of neutrophils was significantly higher (p<0.05) in the S-CIDR+OV and S-CIDR+E2 groups than in Ovsynch group. Comparing the percentage of neutrophils in cervical mucus of Ovsynch group (less than 1%) with that of other treatment groups on the day of AI (from 5 to 39%) revealed the influential effect of a CIDR device on the reproductive tract. Results of the current study did not reveal hormonal effects but did identify mechanical effects of CIDRs on cell percentages in cervical mucus. The hormonal effects were probably masked by mechanical effects. Therefore, we were not able to confirm hormonal effects on proportions of different cells in cervical mucus. Consequently, additional research on hormonal effects and the mechanical effects of CIDR on the uterus is required.

  7. [Titration of Ebola and Marburg viruses by plaque formation under semi liquid agar].

    PubMed

    Ustinova, E N; Shestopalov, A M; Bakulina, L F; Chepurnov, A A

    2003-01-01

    The method of titration of Ebola and Marburg viruses using plaque formation under semifluid agar cover is considered. Advantages of this method over conventional method of titration of these viruses with the use of hard agar cover are discussed.

  8. Comparison between two different methods to obtain the proportions of myoglobin redox forms on fresh meat from reflectance measurements.

    PubMed

    Hernández, B; Sáenz, C; Alberdi, C; Diñeiro, J M

    2015-12-01

    Two procedures based on reflectance (R) measurements to calculate the proportions of deoxymyoglobin (DMb), oxymyoglobin (OMb) and metmyoglobin (MMb) in meat are recommended by the American Meat Science Association (AMSA). One uses the K/S ratios (K and S are the absorption and scattering coefficients) and the other method (Krzywicki 1979) uses the reflex attenuance A = log (1/R). Both methods were compared in: a) synthetic sets of two pigment mixtures and b) 15 samples of beef Longissimus Lumborum measured after 24 h, 4 and 7 days of exposure to air. It was found that K/S and Krzywicki methods gave different values of pigment proportions. However both methods exhibited a high linear correlation (R(2) = 0.8733 in DMb, R(2) = 0.9771 in OMb and R(2) = 0.9390 in MMb, p < 0.0001). This makes them equivalent for statistical analysis based on differences in pigment proportions.

  9. [Detection of TDH-producing Vibrio parahaemolyticus O3:K6 from naturally contaminated shellfish using an immunomagnetic separation method and chromogenic agar medium].

    PubMed

    Hara-Kudo, Y; Sugiyama, K; Nishina, T; Saitoh, A; Nakagawa, H; Ichihara, T; Konuma, H; Hasegawa, J; Kumagai, S

    2001-11-01

    We attempted to isolate TDH-producing Vibrio parahaemolyticus O3:K6 from shellfish. Asari samples were incubated with TSB supplemented with 2% (w/v) NaCl for 6 h, and then the 6-h cultures were incubated with salt polymyxin broth for 18 h. After the two-step enrichment, a 1 ml portion of the culture was treated with magnetic beads coated with K6 antibody for immunoconcentration of V. parahaemolyticus O3:K6. The immunoconcentrated and untreated cultures were plated onto a chromogenic agar and TCBS agar media for isolation of V. parahaemolyticus. TDH-producing V. parahaemolyticus O3:K6 was isolated from 3 out of 66 lots (4.5%) of naturally contaminated Asari. Six of 4,265 colonies suspected as V. parahaemolyticus (0.14%) were TDH-producing V. parahaemolyticus O3:K6.

  10. Abilities of the mCP Agar method and CRENAME alpha toxin-specific real-time PCR assay to detect Clostridium perfringens spores in drinking water.

    PubMed

    Maheux, Andrée F; Bérubé, Eve; Boudreau, Dominique K; Villéger, Romain; Cantin, Philippe; Boissinot, Maurice; Bissonnette, Luc; Bergeron, Michel G

    2013-12-01

    We first determined the analytical specificity and ubiquity (i.e., the ability to detect all or most strains) of a Clostridium perfringens-specific real-time PCR (rtPCR) assay based on the cpa gene (cpa rtPCR) by using a bacterial strain panel composed of C. perfringens and non-C. perfringens Clostridium strains. All non-C. perfringens Clostridium strains tested negative, whereas all C. perfringens strains tested positive with the cpa rtPCR, for an analytical specificity and ubiquity of 100%. The cpa rtPCR assay was then used to confirm the identity of 116 putative C. perfringens isolates recovered after filtration of water samples and culture on mCP agar. Colonies presenting discordant results between the phenotype on mCP agar and cpa rtPCR were identified by sequencing the 16S rRNA and cpa genes. Four mCP(-)/rtPCR(+) colonies were identified as C. perfringens, whereas 3 mCP(+)/rtPCR(-) colonies were identified as non-C. perfringens. The cpa rtPCR was negative with all 51 non-C. perfringens strains and positive with 64 of 65 C. perfringens strains. Finally, we compared mCP agar and a CRENAME (concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment) procedure plus cpa rtPCR (CRENAME + cpa rtPCR) for their abilities to detect C. perfringens spores in drinking water. CRENAME + cpa rtPCR detected as few as one C. perfringens CFU per 100 ml of drinking water sample in less than 5 h, whereas mCP agar took at least 25 h to deliver results. CRENAME + cpa rtPCR also allows the simultaneous and sensitive detection of Escherichia coli and C. perfringens from the same potable water sample. In itself, it could be used to assess the public health risk posed by drinking water potentially contaminated with pathogens more resistant to disinfection.

  11. Multiregional evaluation of the SimPlate heterotrophic plate count method compared to the standard plate count agar pour plate method in water.

    PubMed

    Jackson, R W; Osborne, K; Barnes, G; Jolliff, C; Zamani, D; Roll, B; Stillings, A; Herzog, D; Cannon, S; Loveland, S

    2000-01-01

    A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35 degrees C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0. 95; y = 0.99X + 0.06).

  12. Abilities of the mCP Agar Method and CRENAME Alpha Toxin-Specific Real-Time PCR Assay To Detect Clostridium perfringens Spores in Drinking Water

    PubMed Central

    Maheux, Andrée F.; Bérubé, Ève; Boudreau, Dominique K.; Villéger, Romain; Cantin, Philippe; Boissinot, Maurice; Bissonnette, Luc

    2013-01-01

    We first determined the analytical specificity and ubiquity (i.e., the ability to detect all or most strains) of a Clostridium perfringens-specific real-time PCR (rtPCR) assay based on the cpa gene (cpa rtPCR) by using a bacterial strain panel composed of C. perfringens and non-C. perfringens Clostridium strains. All non-C. perfringens Clostridium strains tested negative, whereas all C. perfringens strains tested positive with the cpa rtPCR, for an analytical specificity and ubiquity of 100%. The cpa rtPCR assay was then used to confirm the identity of 116 putative C. perfringens isolates recovered after filtration of water samples and culture on mCP agar. Colonies presenting discordant results between the phenotype on mCP agar and cpa rtPCR were identified by sequencing the 16S rRNA and cpa genes. Four mCP−/rtPCR+ colonies were identified as C. perfringens, whereas 3 mCP+/rtPCR− colonies were identified as non-C. perfringens. The cpa rtPCR was negative with all 51 non-C. perfringens strains and positive with 64 of 65 C. perfringens strains. Finally, we compared mCP agar and a CRENAME (concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment) procedure plus cpa rtPCR (CRENAME + cpa rtPCR) for their abilities to detect C. perfringens spores in drinking water. CRENAME + cpa rtPCR detected as few as one C. perfringens CFU per 100 ml of drinking water sample in less than 5 h, whereas mCP agar took at least 25 h to deliver results. CRENAME + cpa rtPCR also allows the simultaneous and sensitive detection of Escherichia coli and C. perfringens from the same potable water sample. In itself, it could be used to assess the public health risk posed by drinking water potentially contaminated with pathogens more resistant to disinfection. PMID:24077714

  13. Development of a selective agar plate for the detection of Campylobacter spp. in fresh produce.

    PubMed

    Yoo, Jin-Hee; Choi, Na-Young; Bae, Young-Min; Lee, Jung-Su; Lee, Sun-Young

    2014-10-17

    This study was conducted to develop a selective medium for the detection of Campylobacter spp. in fresh produce. Campylobacter spp. (n=4), non-Campylobacter (showing positive results on Campylobacter selective agar) strains (n=49) isolated from fresh produce, indicator bacteria (n=13), and spoilage bacteria isolated from fresh produce (n=15) were plated on four Campylobacter selective media. Bolton agar and modified charcoal cefoperazone deoxycholate agar (mCCDA) exhibited higher sensitivity for Campylobacter spp. than did Preston agar and Hunt agar, although certain non-Campylobacter strains isolated from fresh produce by using a selective agar isolation method, were still able to grow on Bolton agar and mCCDA. To inhibit the growth of non-Campylobacter strains, Bolton agar and mCCDA were supplemented with 5 antibiotics (rifampicin, polymyxin B, sodium metabisulfite, sodium pyruvate, ferrous sulfate) and the growth of Campylobacter spp. (n=7) and non-Campylobacter strains (n=44) was evaluated. Although Bolton agar supplemented with rifampicin (BR agar) exhibited a higher selectivity for Campylobacter spp. than did mCCDA supplemented with antibiotics, certain non-Campylobacter strains were still able to grow on BR agar (18.8%). When BR agar with various concentrations of sulfamethoxazole-trimethoprim were tested with Campylobacter spp. (n=8) and non-Campylobacter (n=7), sulfamethoxazole-trimethoprim was inhibitory against 3 of 7 non-Campylobacter strains. Finally, we validated the use of BR agar containing 50mg/L sulfamethoxazole (BRS agar) or 0.5mg/L ciprofloxacin (BRCS agar) and other selective agars for the detection of Campylobacter spp. in chicken and fresh produce. All chicken samples were positive for Campylobacter spp. when tested on mCCDA, BR agar, and BRS agar. In fresh produce samples, BRS agar exhibited the highest selectivity for Campylobacter spp., demonstrating its suitability for the detection of Campylobacter spp. in fresh produce.

  14. 48 CFR 401.371 - AGAR Advisories.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false AGAR Advisories. 401.371... ACQUISITION REGULATION SYSTEM Agency Acquisition Regulations 401.371 AGAR Advisories. The SPE may issue AGAR Advisories, consistent with the policies of the FAR and the AGAR, for the following purposes: (a)...

  15. 48 CFR 401.371 - AGAR Advisories.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false AGAR Advisories. 401.371... ACQUISITION REGULATION SYSTEM Agency Acquisition Regulations 401.371 AGAR Advisories. The SPE may issue AGAR Advisories, consistent with the policies of the FAR and the AGAR, for the following purposes: (a)...

  16. The Soft Agar Colony Formation Assay

    PubMed Central

    Borowicz, Stanley; Van Scoyk, Michelle; Avasarala, Sreedevi; Karuppusamy Rathinam, Manoj Kumar; Tauler, Jordi; Bikkavilli, Rama Kamesh; Winn, Robert A.

    2014-01-01

    Anchorage-independent growth is the ability of transformed cells to grow independently of a solid surface, and is a hallmark of carcinogenesis. The soft agar colony formation assay is a well-established method for characterizing this capability in vitro and is considered to be one of the most stringent tests for malignant transformation in cells. This assay also allows for semi-quantitative evaluation of this capability in response to various treatment conditions. Here, we will demonstrate the soft agar colony formation assay using a murine lung carcinoma cell line, CMT167, to demonstrate the tumor suppressive effects of two members of the Wnt signaling pathway, Wnt7A and Frizzled-9 (Fzd-9). Concurrent overexpression of Wnt7a and Fzd-9 caused an inhibition of colony formation in CMT167 cells. This shows that expression of Wnt7a ligand and its Frizzled-9 receptor is sufficient to suppress tumor growth in a murine lung carcinoma model. PMID:25408172

  17. Nonlinear fractional order proportion-integral-derivative active disturbance rejection control method design for hypersonic vehicle attitude control

    NASA Astrophysics Data System (ADS)

    Song, Jia; Wang, Lun; Cai, Guobiao; Qi, Xiaoqiang

    2015-06-01

    Near space hypersonic vehicle model is nonlinear, multivariable and couples in the reentry process, which are challenging for the controller design. In this paper, a nonlinear fractional order proportion integral derivative (NFOPIλDμ) active disturbance rejection control (ADRC) strategy based on a natural selection particle swarm (NSPSO) algorithm is proposed for the hypersonic vehicle flight control. The NFOPIλDμ ADRC method consists of a tracking-differentiator (TD), an NFOPIλDμ controller and an extended state observer (ESO). The NFOPIλDμ controller designed by combining an FOPIλDμ method and a nonlinear states error feedback control law (NLSEF) is to overcome concussion caused by the NLSEF and conversely compensate the insufficiency for relatively simple and rough signal processing caused by the FOPIλDμ method. The TD is applied to coordinate the contradiction between rapidity and overshoot. By attributing all uncertain factors to unknown disturbances, the ESO can achieve dynamic feedback compensation for these disturbances and thus reduce their effects. Simulation results show that the NFOPIλDμ ADRC method can make the hypersonic vehicle six-degree-of-freedom nonlinear model track desired nominal signals accurately and fast, has good stability, dynamic properties and strong robustness against external environmental disturbances.

  18. Comparing the mannitol-egg yolk-polymyxin agar plating method with the three-tube most-probable-number method for enumeration of Bacillus cereus spores in raw and high-temperature, short-time pasteurized milk.

    PubMed

    Harper, Nigel M; Getty, Kelly J K; Schmidt, Karen A; Nutsch, Abbey L; Linton, Richard H

    2011-03-01

    The U.S. Food and Drug Administration's Bacteriological Analytical Manual recommends two enumeration methods for Bacillus cereus: (i) standard plate count method with mannitol-egg yolk-polymyxin (MYP) agar and (ii) a most-probable-number (MPN) method with tryptic soy broth (TSB) supplemented with 0.1% polymyxin sulfate. This study compared the effectiveness of MYP and MPN methods for detecting and enumerating B. cereus in raw and high-temperature, short-time pasteurized skim (0.5%), 2%, and whole (3.5%) bovine milk stored at 4°C for 96 h. Each milk sample was inoculated with B. cereus EZ-Spores and sampled at 0, 48, and 96 h after inoculation. There were no differences (P > 0.05) in B. cereus populations among sampling times for all milk types, so data were pooled to obtain overall mean values for each treatment. The overall B. cereus population mean of pooled sampling times for the MPN method (2.59 log CFU/ml) was greater (P < 0.05) than that for the MYP plate count method (1.89 log CFU/ml). B. cereus populations in the inoculated milk samples ranged from 2.36 to 3.46 and 2.66 to 3.58 log CFU/ml for inoculated milk treatments for the MYP plate count and MPN methods, respectively, which is below the level necessary for toxin production. The MPN method recovered more B. cereus, which makes it useful for validation research. However, the MYP plate count method for enumeration of B. cereus also had advantages, including its ease of use and faster time to results (2 versus 5 days for MPN).

  19. Performance of the EUCAST disk diffusion method, the CLSI agar screen method, and the Vitek 2 automated antimicrobial susceptibility testing system for detection of clinical isolates of Enterococci with low- and medium-level VanB-type vancomycin resistance: a multicenter study.

    PubMed

    Hegstad, Kristin; Giske, Christian G; Haldorsen, Bjørg; Matuschek, Erika; Schønning, Kristian; Leegaard, Truls M; Kahlmeter, Gunnar; Sundsfjord, Arnfinn

    2014-05-01

    Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n=28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n=12) and Enterococcus faecium (n=18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n=5), Norwegian (n=13), and Swedish (n=10) laboratories using the EUCAST disk diffusion method (n=28) and the CLSI agar screen (n=18) or the Vitek 2 system (bioMérieux) (n=5). The EUCAST disk diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P=0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST disk diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P<0.0001) or Merck Mueller-Hinton (MH) agar (P=0.027) for the disk diffusion assay performed significantly better than did laboratories using BBL MH II medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P=0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST disk diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, disk diffusion methodology requires that personnel be trained in interpreting zone edges.

  20. Adaptation through proportion

    NASA Astrophysics Data System (ADS)

    Xiong, Liyang; Shi, Wenjia; Tang, Chao

    2016-08-01

    Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network. Adaptation can be achieved by using any two nodes in the sub-network to respectively regulate the output node positively and negatively. We focus on enzyme networks and first identify basic regulation motifs consisting of two and three nodes that can be used to build small networks with proportional relationships. Larger proportional networks can then be constructed modularly similar to LEGOs. Our method provides a general framework to construct and analyze a class of proportional and/or adaptation networks with arbitrary size, flexibility and versatile functional features.

  1. Crystal formation in furunculosis agar

    USGS Publications Warehouse

    Bullock, G.L.; Ross, A.J.

    1964-01-01

    SINCE ITS INTRODUCTION SOME MONTHS AGO, FURUNCULOSIS AGAR has been employed in the diagnosis of suspect furunculosis and also as a general purpose medium. During our work with this medium we have noticed discrete "colonies," of crystalline material, which very closely resemble microbial colonies. These crystal colonies are compact and appear on both the surface and subsurface; they occur in inoculated slants and plates incubated for long periods (2 to 3 weeks), as well as in uninoculated stored medium. As the crystal colonies could be confusing to workers using this medium, we decided to attempt to identify them and also to determine whether storage conditions and different lots of medium affect crystal formation.

  2. Replica plating of colonies from Listeria-selective agars to blood agar to improve the isolation of Listeria monocytogenes from foods.

    PubMed

    Cassiday, P K; Graves, L M; Swaminathan, B

    1990-07-01

    Bacterial colonies from Listeria-selective agars were replica plated to sheep blood agar to screen for beta-hemolysis. By using the replica plating method to test for the beta-hemolytic characteristic of all the colonies growing on Listeria-selective agars instead of picking 3 to 10 suspected colonies for further testing, we recovered Listeria monocytogenes from 59 of 142 Listeria-selective agar plates which contained colonies of hemolytic and nonhemolytic Listeria species and were negative when tested by conventional colony picks.

  3. Application of Microbiological Method Direct Epifluorescence Filter Techique/Aerobic Plate Count Agar in the Identification of Irradiated Herbs and Spices

    PubMed Central

    Di Schiavi, Maria Teresa; Foti, Marina; Mosconi, Maria Cristina; Mattiolo, Giuseppina; Cavallina, Roberta

    2014-01-01

    Irradiation is a preservation technology used to improve the safety and hygienic quality of food. Aim of this study was to assess the applicability and validity of the microbiological screening method direct epifluorescence filter technique (DEFT)/aerobic plate count (APC) (EN 13783:2001) for the identification of irradiated herbs and spices. Tests on non-irradiated and irradiated samples of dried herbs and spices were performed. The method was based on the comparison of APC and count obtained using DEFT. In accordance with the standard reference, this method is not applicable to samples with APC<103 colony forming units (CFU)/g and this is its main limit. The results obtained in our laboratories showed that in 50% of cases of non-irradiated samples and in 96% of the samples treated with ionising radiation, the method was not applicable due to a value of CFU/g <103. PMID:27800348

  4. Residual Agar Determination in Bacterial Spores by Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Wahl, Karen L.; Colburn, Heather A.; Wunschel, David S.; Petersen, Catherine E.; Jarman, Kristin H.; Valentine, Nancy B.

    2010-02-15

    Presented here is an analytical method to detect residual agar from a bacterial spore sample as an indication of culturing on an agar plate. This method is based on the resolubilization of agar polysaccharide from a bacterial spore sample, enzymatic digestion, followed by electrospray ionization tandem mass spectrometry (ESI-MSn) analysis for detection of a specific agar fragment ion. A range of Bacillus species and strains were selected to demonstrate the effectiveness of this approach. The characteristic agar fragment ion was detected in the spores grown on agar that were washed from 1 to 5 times, irradiated or non-irradiated and not in the spores grown in broth. A sample containing approximately 108 spores is currently needed for confident detection of residual agar from culture on agar plates in the presence of bacterial spores with a limit of detection of approximately 1 ppm agar spiked into a broth-grown spore sample. The results of a proficiency test with 42 blinded samples are presented demonstrating the utility of this method with no false positives and only 3 false negatives for samples that were below the detection level of the method as documented.

  5. Agar polysaccharides from Gracilaria species (Rhodophyta, Gracilariaceae).

    PubMed

    Marinho-Soriano, E

    2001-07-26

    Yield, physical and chemical properties of agar from three agarophytes species (Gracilaria gracilis, G. dura and G. bursa-pastoris) were determined. The agar yield from the three species varied significantly (P<0.01). The highest yields of agar (34.8%) and the lowest (30%) were obtained from G. bursa-pastoris and G. gracilis, respectively. Highest gel strength (630+/-15 g cm(-2)) was obtained from agar extracted from G. gracilis and lowest from G. bursa-pastoris (26+/-3.6 g cm(-2)). The values of 3,6-anhydrogalactose were similar for G. gracilis and G. dura and there were no significant differences among the species. The sulfate contents varied significantly (P<0.01) and the higher value was obtained from G. bursa-pastoris. Among the three species, G. gracilis showed superior agar quality than the other two species, hence it can be considered a good potential source for industrial use.

  6. Multiwire proportional chamber development

    NASA Technical Reports Server (NTRS)

    Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.

    1973-01-01

    The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.

  7. Recovery of Sublethally Injured Bacteria Using Selective Agar Overlays.

    ERIC Educational Resources Information Center

    McKillip, John L.

    2001-01-01

    This experiment subjects bacteria in a food sample and an environmental sample to conditions of sublethal stress in order to assess the effectiveness of the agar overlay method to recover sublethally injured cells compared to direct plating onto the appropriate selective medium. (SAH)

  8. Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars.

    PubMed

    Brusa, Victoria; Piñeyro, Pablo E; Galli, Lucía; Linares, Luciano H; Ortega, Emanuel E; Padola, Nora L; Leotta, Gerardo A

    2016-03-01

    Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground beef samples, and (2) to evaluate the most efficient combination(s) of methods for naturally contaminated ground beef samples. A total of 192 ground beef samples were artificially inoculated with STEC and non-stx bacterial strains. A combination of four enrichment broths and three agars were evaluated for sensitivity, specificity, and positive predictive value for STEC isolation from experimentally inoculated samples. Enrichments with either modified tryptic soy broth (mTSB) containing 8 mg/L novobiocin (mTSB-8) or modified Escherichia coli (mEC) broth followed by isolation in MacConkey agar were the most sensitive combinations for STEC isolation of artificially inoculated samples. Independently, both enrichments media followed by isolation in MacConkey were used to evaluate ground beef samples from 43 retail stores, yielding 65.1% and 58.1% stx-positive samples by RT-PCR, respectively. No difference was observed in the isolate proportions between these two methods (8/25 [32%] and 8/28 [28.6%]). Identical serotypes and stx genotypes were observed in STEC strains isolated from the same samples by either method. In this study, no single enrichment protocol was sufficient to detect all STEC in artificially inoculated samples and had considerable variation in detection ability with naturally contaminated samples. Moreover, none of the single or combinations of multiple isolation agars used were capable of identifying all STEC serogroups in either artificially inoculated or naturally occurring STEC-contaminated ground beef. Therefore, it may be prudent to conclude that there is no single method or combination of isolation methods capable of identifying all STEC serogroups

  9. Testing susceptibility of multidrug-resistant Mycobacterium tuberculosis to second-line drugs by use of blood agar.

    PubMed

    Satana, Dilek; Coban, Ahmet Yilmaz; Uzun, Meltem

    2010-11-01

    In this study, the susceptibilities of 35 multidrug-resistant (MDR) Mycobacterium tuberculosis clinical isolates to second-line drugs, including kanamycin (KM), rifabutin (RBU), ofloxacin (OFX), p-aminosalicylic acid (PAS), capreomycin (CAP), clofazimine (CFM), and ethionamide (ETH), were investigated on blood agar according to CLSI recommendations. Compared with the results of the Bactec 460 TB system, agreement was 100, 100, 97, 100, 100, 100, and 86% for KM, RBU, OFX, PAS, CAP, CFM, and ETH, respectively. Compared with the results of the proportion method, agreement was 100, 100, 97, 100, 97, 100, and 77% for KM, RBU, OFX, PAS, CAP, CFM, and ETH, respectively.

  10. Growth kinetics of three species of Tetrahymena on solid agar

    SciTech Connect

    Dobra, K.W.; McArdle, E.W.; Ehret, C.F.

    1980-01-01

    A nutrient-agar method without liquid overlay has been developed for cultivation of ciliates. Three species of Tetrahymena-T. pyriformis strain W, T. rostrata strain UNI, and T. vorax strain V/sub 2/S, representing the 3 main groups of Tetrahymena species, were used; however the method should apply to other ciliates. Growth on the surface of the agar was facilitated by an optimal surface-to-volume ratio yielding a high density of ciliates and short generation times. At the highest density achieved, the cells became irregularly hexagonal and formed a monolayer tissue on the agar. Ciliates grown on agar were like those in liquid culture, typical oral ciliature, food-vacuole formation, and typical cortical patterns being retained. Advantages of this method include high cell density, easy recovery, and optimal O/sub 2/ supply. The organisms can also be cultivated on the surface of sterile cellulose-nitrate filters, facilitating in situ fixation and staining as well as transfer into different media by transfer of filters with cells, without prior centrifugation and resuspension.

  11. Bacterial pathogens of otitis media and sinusitis: detection in the nasopharynx with selective agar media.

    PubMed

    Dudley, S; Ashe, K; Winther, B; Hendley, J O

    2001-11-01

    Carriage rates for the bacterial pathogens associated with otitis media (Streptococcus pneumoniae [SP], Hemophilus influenzae [HI], and Moraxella catarrhalis [MC]) are of interest. Culture on three selective agars was compared with culture on two standard agars to determine the more accurate method for detection of these species in the nasopharynx of healthy children. Weekly samples were obtained in winter from 18 healthy children (ages 1 through 9 years) as part of a longitudinal study. A 0.1-mL sample of 116 nasopharyngeal aspirate/washes was inoculated onto each of five agars. Two were standard (sheep blood and chocolate), and three were selective (blood with gentamicin for SP; chocolate with vancomycin, bacitracin, and clindamycin for HI; blood with amphotericin B, vancomycin, trimethoprim, and acetazolamide for MC). One technician read the standard plates and another the selective; both were blinded to the results of the other. SP was found in 44% of samples with selective agar versus 25% with standard agar; HI was found in 31% with selective versus 9% with standard; MC was found in 56% with selective versus 37% with standard. Overall, 80% of samples had one or more pathogens detected with selective agars as compared with 58% with standard agars (P =.0004). Selective agars were more accurate than standard agars for detecting otitis pathogens in the nasopharynx, where they are a common part of normal flora in healthy children.

  12. Multiple Ways to Solve Proportions

    ERIC Educational Resources Information Center

    Ercole, Leslie K.; Frantz, Marny; Ashline, George

    2011-01-01

    When solving problems involving proportions, students may intuitively draw on strategies that connect to their understanding of fractions, decimals, and percents. These two statements--"Instruction in solving proportions should include methods that have a strong intuitive basis" and "Teachers should begin instruction with more intuitive…

  13. Some Experiments With Agar-Grown Seedlings

    ERIC Educational Resources Information Center

    Freeland, P. W.

    1973-01-01

    Two percent agar gel is reported as a better medium for germination and growth studies. Students can be encouraged to undertake many simple experiments and make precise observations by using this medium. (PS)

  14. Characterization of physicochemical properties of carboxymethyl agar.

    PubMed

    Cao, Mingzhao; Liu, Xin; Luan, Jimei; Zhang, Xiaodong

    2014-10-13

    A series of carboxymethyl agars (CMAs) with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that with the increase of DS, the dissolving temperature, the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, and the solution apparent viscosity of CMA all decreased, except that its gel cohesiveness and gel springiness increased. The variation process of agar molecules in solution from coil to helix could be observed by measuring the optical rotation of the solution at such a low concentration, at which even the solution could not form a gel. The gel skeleton microstructures of both agar and CMA were of porous network structure, and the pore size of CMA became smaller and denser with the increase of its DS. After carboxymethylation, the agar hygroscopicity was improved, but its thermal stability was lowered.

  15. Differentiation of Candida dubliniensis from Candida albicans on rosemary extract agar and oregano extract agar.

    PubMed

    de Loreto, Erico Silva; Pozzatti, Patrícia; Alves Scheid, Liliane; Santurio, Deise; Morais Santurio, Janio; Alves, Sydney Hartz

    2008-01-01

    Candida dubliniensis is a recently described pathogenic species which shares many phenotypic features with Candida albicans and therefore, may be misidentified in microbiological laboratories. Because molecular methods can be onerous and unfeasible in routine mycological laboratories with restricted budgets such as those in developing countries, phenotypic techniques have been encouraged in the development of differential media for the presumptive identification of these species. We examined the colony morphology and chlamydospore production of 30 C. dubliniensis isolates and 100 C. albicans isolates on two new proposed media: rosemary (Rosmarinus officinalis) extract agar (REA) and oregano (Origanum vulgare) extract agar (OEA). These substrates are traditionally used as spices and medicinal herbs. In both of these media, all C. dubliniensis isolates (100%) showed rough colonies with peripheral hyphal fringes and abundant chlamydospores after 24 to 48 hr of incubation at 25 degrees C. In contrast, under the same conditions, all isolates of C. albicans (100%) showed smooth colonies without hyphal fringes or chlamydospores. In conclusion, REA and OEA offer a simple, rapid, and inexpensive screening media for the differentiation of C. albicans and C. dubliniensis.

  16. Agar composition affects in vitro screening of biocontrol activity of antagonistic microorganisms.

    PubMed

    Bosmans, L; De Bruijn, I; De Mot, R; Rediers, H; Lievens, B

    2016-08-01

    Agar-based screening assays are the method of choice when evaluating antagonistic potential of bacterial biocontrol-candidates against pathogens. We showed that when using the same medium, but different agar compositions, the activity of a bacterial antagonist against Agrobacterium was strongly affected. Consequently, results from in vitro screenings should be interpreted cautiously. PMID:27166668

  17. Fusobacterium necrophorum- detection and identification on a selective agar.

    PubMed

    Bank, Steffen; Nielsen, Hanne Merete; Mathiasen, Boris Hoyer; Leth, Dorte Christiansen; Kristensen, Lena Hagelskjaer; Prag, Jørgen

    2010-12-01

    Within the last decade, Fusobacterium necrophorum subsp. funduliforme has been considered a clinically important pathogen causing pharyngitis especially in adolescents and young adults. F. necrophorum pharyngitis can progress into Lemierre's syndrome, which is a severe and life-threatening infection. However, throat swabs are not cultured anaerobically in the routine and even if cultured anaerobically, it can be difficult to identify F. necrophorum from the normal flora of the throat. F. necrophorum is therefore often overlooked as the cause of pharyngitis. In our laboratory, a F. necrophorum selective agar has been developed containing vancomycin and nalidixin, which inhibit the growth of most Gram-positive and many Gram-negative bacteria, respectively. β-haemolysis of horse blood can be detected, which further facilitates the detection and identification of F. necrophorum. The F. necrophorum selective agar was evaluated against a quantitative real-time polymerase chain reaction assay and shown to have a significantly higher sensitivity for detecting F. necrophorum than the anaerobic agar commonly used in Denmark. Furthermore, the F. necrophorum selective agar does not require experienced laboratory technicians, require fewer subcultures, is probably less expensive and is faster to perform than other culture methods.

  18. Methicillin-Resistant Staphylococcus aureus (MRSA) Detection: Comparison of Two Molecular Methods (IDI-MRSA PCR Assay and GenoType MRSA Direct PCR Assay) with Three Selective MRSA Agars (MRSA ID, MRSASelect, and CHROMagar MRSA) for Use with Infection-Control Swabs▿

    PubMed Central

    van Hal, S. J.; Stark, D.; Lockwood, B.; Marriott, D.; Harkness, J.

    2007-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing problem. Rapid detection of MRSA-colonized patients has the potential to limit spread of the organism. We evaluated the sensitivities and specificities of MRSA detection by two molecular methods (IDI-MRSA PCR assay and GenoType MRSA Direct PCR assay) and three selective MRSA agars (MRSA ID, MRSASelect, and CHROMagar MRSA), using 205 (101 nasal, 52 groin, and 52 axillary samples) samples from consecutive known MRSA-infected and/or -colonized patients. All detection methods had higher MRSA detection rates for nasal swabs than for axillary and groin swabs. Detection of MRSA by IDI-MRSA was the most sensitive method, independent of the site (94% for nasal samples, 80% for nonnasal samples, and 90% overall). The sensitivities of the GenoType MRSA Direct assay and the MRSA ID, MRSASelect, and CHROMagar MRSA agars with nasal swabs were 70%, 72%, 68%, and 75%, respectively. All detection methods had high specificities (95 to 99%), independent of the swab site. Extended incubation for a further 24 h with selective MRSA agars increased the detection of MRSA, with a corresponding decline in specificity secondary to a significant increase in false-positive results. There was a noticeable difference in test performance of the GenoType MRSA Direct assay in detection of MRSA (28/38 samples [74%]) compared with detection of nonmultiresistant MRSA (17/31 samples [55%]) (susceptible to two or more non-β-lactam antibiotics). This was not observed with selective MRSA agar plates or IDI-MRSA. Although it is more expensive, in addition to rapid turnaround times of 2 to 4 h, IDI-MRSA offers greater detection of MRSA colonization, independent of the swab site, than do conventional selective agars and GenoType MRSA Direct. PMID:17537949

  19. Strip Diagrams: Illuminating Proportions

    ERIC Educational Resources Information Center

    Cohen, Jessica S.

    2013-01-01

    Proportional reasoning is both complex and layered, making it challenging to define. Lamon (1999) identified characteristics of proportional thinkers, such as being able to understand covariance of quantities; distinguish between proportional and nonproportional relationships; use a variety of strategies flexibly, most of which are nonalgorithmic,…

  20. Delta method and bootstrap in linear mixed models to estimate a proportion when no event is observed: application to intralesional resection in bone tumor surgery.

    PubMed

    Francq, Bernard G; Cartiaux, Olivier

    2016-09-10

    Resecting bone tumors requires good cutting accuracy to reduce the occurrence of local recurrence. This issue is considerably reduced with a navigated technology. The estimation of extreme proportions is challenging especially with small or moderate sample sizes. When no success is observed, the commonly used binomial proportion confidence interval is not suitable while the rule of three provides a simple solution. Unfortunately, these approaches are unable to differentiate between different unobserved events. Different delta methods and bootstrap procedures are compared in univariate and linear mixed models with simulations and real data by assuming the normality. The delta method on the z-score and parametric bootstrap provide similar results but the delta method requires the estimation of the covariance matrix of the estimates. In mixed models, the observed Fisher information matrix with unbounded variance components should be preferred. The parametric bootstrap, easier to apply, outperforms the delta method for larger sample sizes but it may be time costly. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Agar agar-stabilized milled zerovalent iron particles for in situ groundwater remediation.

    PubMed

    Velimirovic, Milica; Schmid, Doris; Wagner, Stephan; Micić, Vesna; von der Kammer, Frank; Hofmann, Thilo

    2016-09-01

    Submicron-scale milled zerovalent iron (milled ZVI) particles produced by grinding macroscopic raw materials could provide a cost-effective alternative to nanoscale zerovalent iron (nZVI) particles for in situ degradation of chlorinated aliphatic hydrocarbons in groundwater. However, the aggregation and settling of bare milled ZVI particles from suspension presents a significant obstacle to their in situ application for groundwater remediation. In our investigations we reduced the rapid aggregation and settling rate of bare milled ZVI particles from suspension by stabilization with a "green" agar agar polymer. The transport potential of stabilized milled ZVI particle suspensions in a diverse array of natural heterogeneous porous media was evaluated in a series of well-controlled laboratory column experiments. The impact of agar agar on trichloroethene (TCE) removal by milled ZVI particles was assessed in laboratory-scale batch reactors. The use of agar agar significantly enhanced the transport of milled ZVI particles in all of the investigated porous media. Reactivity tests showed that the agar agar-stabilized milled ZVI particles were reactive towards TCE, but that their reactivity was an order of magnitude less than that of bare, non-stabilized milled ZVI particles. Our results suggest that milled ZVI particles could be used as an alternative to nZVI particles as their potential for emplacement into contaminated zone, their reactivity, and expected longevity are beneficial for in situ groundwater remediation.

  2. Comparative Evaluation of Löwenstein-Jensen Proportion Method, BacT/ALERT 3D System, and Enzymatic Pyrazinamidase Assay for Pyrazinamide Susceptibility Testing of Mycobacterium tuberculosis▿

    PubMed Central

    Singh, Pushpendra; Wesley, Clement; Jadaun, G. P. S.; Malonia, Sunil Kumar; Das, R.; Upadhyay, P.; Faujdar, J.; Sharma, P.; Gupta, P.; Mishra, Abhay Kumar; Singh, Kalpana; Chauhan, D. S.; Sharma, V. D.; Gupta, U. D.; Venkatesan, K.; Katoch, V. M.

    2007-01-01

    Pyrazinamide (PZA) is an important first-line antituberculosis drug because of its sterilizing activity against semidormant tubercle bacilli. In spite of its very high in vivo activity, its in vitro activity is not apparent unless an acidic environment is available, which makes PZA susceptibility testing difficult by conventional methods. The present study was, therefore, planned to assess the performance of the colorimetric BacT/ALERT 3D system and compare the results with those from conventional tests, i.e., the Löwenstein-Jensen (LJ) proportion method (pH 4.85) and Wayne's pyrazinamidase (PZase) assay, using 107 clinical isolates. The concordance among all of these tests was 89.71% after the first round of testing and reached 92.52% after resolution of the discordant results by retesting. Prolonged incubation of the PZase tube for up to 10 days was found to increase the specificity of the PZase test. The concordances between LJ proportion and BacT/ALERT 3D, LJ proportion and the PZase assay, and BacT/ALERT 3D and the PZase assay were found to be 99.06%, 93.46%, and 92.52%, respectively. Using the LJ results as the gold standard, the sensitivities of BacT/ALERT 3D and the PZase assay were 100 and 82.85%, respectively, while the specificity was 98.61% for both of the tests. The difference between the sensitivities of BacT/ALERT 3D and the PZase assay was significant (P = 0.025). The mean turnaround times for the detection of resistant and susceptible results by BacT/ALERT 3D were 8.04 and 11.32 days, respectively. While the major limitations associated with the PZase assay and the LJ proportion method are lower sensitivity in previously treated patients and a longer time requirement, respectively, the BacT/ALERT 3D system was found to be rapid, highly sensitive, and specific. PMID:17093022

  3. Standard operating procedure to prepare agar phantoms

    NASA Astrophysics Data System (ADS)

    Souza, R. M.; Santos, T. Q.; Oliveira, D. P.; Souza, R. M.; Alvarenga, A. V.; Costa-Felix, R. P. B.

    2016-07-01

    Agar phantoms are widely used as soft tissue mimics and some preparation techniques are described in the literature. There are also standards that describe the recipe of a soft tissue mimicking material (TMM). However some details of manufacture process are not clearly defined. The standardization of the phantom's preparation can produce a metrological impact on the results of the acoustic properties measured. In this direction, this paper presents a standard operating procedure (SOP) to prepare the agar TMM described on the IEC 60601-237.

  4. A NEW SELECTIVE BLOOD AGAR MEDIUM FOR STREPTOCOCCUS PYOGENES AND OTHER HAEMOLYTIC STREPTOCOCCI.

    PubMed

    LOWBURY, E J; KIDSON, A; LILLY, H A

    1964-05-01

    Horse blood agar containing polymyxin B sulphate, neomycin sulphate, and fusidic acid inhibited the growth of Staph. aureus, Ps. pyocyanea, Proteus mirabilis, E. coli, and Klebsiella pneumoniae but allowed good growth of, and haemolysis by, Str. pyogenes. In a comparison with blood agar, blood 4% agar, and gentian violet blood agar, the selective medium (P.N.F.) yielded a significantly higher proportion of streptococci than the other media, both by aerobic and by anaerobic culture, from burn swab extracts deliberately contaminated with Str. pyogenes; P.N.F. culture was more effective with dilute than with heavy inocula of Str. pyogenes, allowing from three to seven times as many recoveries of Str. pyogenes from swabs contaminated with 10(-3) dilution of streptococcal cultures than cultures of the same material on the other media. Haemolytic streptococci of groups A, C, D, G, and others were isolated by aerobic culture from burns in a consecutive series of 1,277 swabs more often on P.N.F. medium than on blood 4% agar. Viable counts of 12 strains (including 11 different serological types) of Str. pyogenes showed some reduction in the numbers of colonies compared with counts on blood agar, and some strains grew more slowly on P.N.F. medium. These limitations, however, were offset and outweighed by the higher final yield of streptococci on the selective medium.

  5. A novel agar formulation for isolation and direct enumeration of Vibrio vulnificus from oyster tissue.

    PubMed

    Griffitt, Kimberly J; Grimes, D Jay

    2013-08-01

    A new selective and differential medium, Vibrio vulnificus X-Gal (VVX), was developed for direct enumeration of V. vulnificus (Vv) from oyster samples. This agar utilizes cellobiose and lactose as carbon sources, and the antibiotics colistin and polymyxin B as selective agents. Hydrolysis of 5-bromo-4-chloro-3-indolyl- beta-d-galactopyranoside (x-gal), used in the agar as a lactose analog, produces an insoluble blue dye that makes lactose positive colonies easily distinguishable from any non-lactose fermenting bacteria. Various bacterial species were spot plated onto thiosulfate-citrate-bile salts-sucrose agar (TCBS), and CHROMagar Vibrio, two vibrio-specific selective agars, non-selective agar, and VVX to compare selectivity of VVX to other widely used media. A V. vulnificus pure culture was serially diluted on VVX and non-selective agar to determine the VVX percent recovery. Water and oyster samples were spread plated on VVX agar and allowed to incubate for 16-18 h at 33 °C. Blue and white colonies from VVX agar were picked and screened by end point PCR for the Vv hemolysin vvhA. VVX agar showed a significant improvement over TCBS and CHROMagar at preventing non-target growth. There was an 87.5% recovery compared to non-selective plating and a 98% positivity rate of blue colonies picked from oyster tissue plating. The findings suggest that this new agar is a fast, distinctive, and accurate method for enumeration of V. vulnificus from the environment.

  6. Use of agar agar stabilized milled zero-valent iron particles for in situ groundwater remediation

    NASA Astrophysics Data System (ADS)

    Schmid, Doris; Velimirović, Milica; Wagner, Stephan; Micić Batka, Vesna; von der Kammer, Frank; Hofmann, Thilo

    2015-04-01

    A major obstacle for use of nanoscale zero-valent iron (nZVI) particles as a nontoxic material for effective in situ degradation of chlorinated aliphatic hydrocarbons (CAHs) is the high production cost. For that reason, submicro-scale milled zero-valent iron particles were recently developed (milled ZVI, UVR-FIA, Germany) by grinding macroscopic raw materials of elementary iron as a cheaper alternative to products produced by solid-state reduction. However, milled ZVI particles tend to aggregate and due to the rather large particle size (d50= 11.9 µm) also rapidly sediment. To prevent aggregation and consequently sedimentation of milled ZVI particles and therefore improve the mobility after in situ application, the use of a stabilizer is considered in literature as a most promising option. In this study, milled ZVI particles (1 g L-1 of particle concentration) were stabilized by environmentally friendly polymer agar agar (>0.5 g L-1), which had a positive impact on the milled ZVI stability. Sedimentation rate was significantly decreased by increasing the suspension viscosity. Column transport experiments were performed for bare and agar agar stabilized milled ZVI particles in commercially available fine grained quartz sand (DORSILIT® Nr.8, Gebrüder Dorfner GmbH Co, Germany) and different porous media collected from brownfields. The experiments were carried out under field relevant injection conditions of 100 m d-1. The maximal travel distance (LT) of less than 10 cm was determined for non-stabilized suspension in fine grained quartz sand, while agar agar (1 g L-1) stabilized milled ZVI suspension revealed LT of 12 m. Similar results were observed for porous media from brownfields showing that mobility of agar agar stabilized particle suspensions was significantly improved compared to bare particles. Based on the mobility data, agar agar stabilized milled zero-valent iron particles could be used for in situ application. Finally, lab-scale batch degradation

  7. Comparison of dosimetry gels prepared by agar and bovine gelatine

    NASA Astrophysics Data System (ADS)

    Sağsöz, M. E.; Korkut, Ö.; Alemdar, N.; Aktaş, S.; Çalı, E. B.; Kantarcı, M.

    2016-04-01

    Gel dosimeters are unique materials capable of showing three dimensional (3D) dose distributions of therapeutic or diagnostic exposures. Fricke gel dosimeters can be considered as chemical dosimeters that rely on a radiation-induced chemical reaction. Dose distribution of Fricke solutions containing Fe+2 ions determines the transformation of acidic, oxygen saturated Fe+2 ions to Fe+3 ions by the ionizing radiation in aqueous solutions. In this study we produced two different types of gel dosimeters using agar and bovine gelatin with similar fabrication methods. We compared the magnetic resonance (MR) T1 imaging responses of these two gel dosimeters to acquire a dose dependency of MR intensities. In conclusion agar gel dosimeters found to be produced easily and more consistent.

  8. Luminescent DNA- and agar-based membranes.

    PubMed

    Leones, R; Fernandes, M; Ferreira, R A S; Cesarino, I; Lima, J F; Carlos, L D; Bermudez, V de Zea; Magon, C J; Donoso, J P; Silva, M M; Pawlicka, A

    2014-09-01

    Luminescent materials containing europium ions are investigated for different optical applications. They can be obtained using bio-macromolecules, which are promising alternatives to synthetic polymers based on the decreasing oil resources. This paper describes studies of the DNA- and Agar-europium triflate luminescent membranes and its potential technological applications are expanded to electroluminescent devices. Polarized optical microscopy demonstrated that the samples are birefringent with submicrometer anisotropy. The X-ray diffraction analysis revealed predominantly amorphous nature of the samples and the atomic force microscopy images showed a roughness of the membranes of 409.0 and 136.1 nm for the samples of DNA10Eu and Agar1.11Eu, respectively. The electron paramagnetic resonance spectra of the DNA(n)Eu membranes with the principal lines at g ≈ 2.0 and g ≈ 4.8 confirmed uniform distribution of rare earth ions in a disordered matrix. Moreover, these strong and narrow resonance lines for the samples of DNA(n)Eu when compared to the Agar(n)Eu suggested a presence of paramagnetic radicals arising from the DNA matrix. The emission spectra suggested that the Eu3+ ions occupy a single local environment in both matrices and the excitation spectra monitored around the Eu emission lines pointed out that the Eu3+ ions in the Agar host were mainly excited via the broad band component rather than by direct intra-4f(6) excitation, whereas the opposite case occurred for the DNA-based sample.

  9. Proportional Topology Optimization: A New Non-Sensitivity Method for Solving Stress Constrained and Minimum Compliance Problems and Its Implementation in MATLAB

    PubMed Central

    Biyikli, Emre; To, Albert C.

    2015-01-01

    A new topology optimization method called the Proportional Topology Optimization (PTO) is presented. As a non-sensitivity method, PTO is simple to understand, easy to implement, and is also efficient and accurate at the same time. It is implemented into two MATLAB programs to solve the stress constrained and minimum compliance problems. Descriptions of the algorithm and computer programs are provided in detail. The method is applied to solve three numerical examples for both types of problems. The method shows comparable efficiency and accuracy with an existing optimality criteria method which computes sensitivities. Also, the PTO stress constrained algorithm and minimum compliance algorithm are compared by feeding output from one algorithm to the other in an alternative manner, where the former yields lower maximum stress and volume fraction but higher compliance compared to the latter. Advantages and disadvantages of the proposed method and future works are discussed. The computer programs are self-contained and publicly shared in the website www.ptomethod.org. PMID:26678849

  10. Proportional Topology Optimization: A New Non-Sensitivity Method for Solving Stress Constrained and Minimum Compliance Problems and Its Implementation in MATLAB.

    PubMed

    Biyikli, Emre; To, Albert C

    2015-01-01

    A new topology optimization method called the Proportional Topology Optimization (PTO) is presented. As a non-sensitivity method, PTO is simple to understand, easy to implement, and is also efficient and accurate at the same time. It is implemented into two MATLAB programs to solve the stress constrained and minimum compliance problems. Descriptions of the algorithm and computer programs are provided in detail. The method is applied to solve three numerical examples for both types of problems. The method shows comparable efficiency and accuracy with an existing optimality criteria method which computes sensitivities. Also, the PTO stress constrained algorithm and minimum compliance algorithm are compared by feeding output from one algorithm to the other in an alternative manner, where the former yields lower maximum stress and volume fraction but higher compliance compared to the latter. Advantages and disadvantages of the proposed method and future works are discussed. The computer programs are self-contained and publicly shared in the website www.ptomethod.org. PMID:26678849

  11. Proportional Topology Optimization: A New Non-Sensitivity Method for Solving Stress Constrained and Minimum Compliance Problems and Its Implementation in MATLAB.

    PubMed

    Biyikli, Emre; To, Albert C

    2015-01-01

    A new topology optimization method called the Proportional Topology Optimization (PTO) is presented. As a non-sensitivity method, PTO is simple to understand, easy to implement, and is also efficient and accurate at the same time. It is implemented into two MATLAB programs to solve the stress constrained and minimum compliance problems. Descriptions of the algorithm and computer programs are provided in detail. The method is applied to solve three numerical examples for both types of problems. The method shows comparable efficiency and accuracy with an existing optimality criteria method which computes sensitivities. Also, the PTO stress constrained algorithm and minimum compliance algorithm are compared by feeding output from one algorithm to the other in an alternative manner, where the former yields lower maximum stress and volume fraction but higher compliance compared to the latter. Advantages and disadvantages of the proposed method and future works are discussed. The computer programs are self-contained and publicly shared in the website www.ptomethod.org.

  12. Coincidence Proportional Counter

    DOEpatents

    Manley, J H

    1950-11-21

    A coincidence proportional counter having a plurality of collecting electrodes so disposed as to measure the range or energy spectrum of an ionizing particle-emitting source such as an alpha source, is disclosed.

  13. Evaluation of Granada agar plate for detection of Streptococcus agalactiae in urine specimens from pregnant women.

    PubMed

    Tamayo, Javier; Gómez-Garcés, José-Luis; Alós, Juan-Ignacio

    2004-08-01

    The Granada agar plate (GAP; Biomedics SL, Madrid, Spain) was evaluated for the detection of group B streptococci (GBS) in urine specimens from pregnant women submitted for testing for asymptomatic bacteriuria and was compared with blood agar (BA [Columbia agar with 5% sheep blood]; bioMérieux, Marcy l'Etoile, France). The GAP detected 103 out of 105 GBS, whereas BA detected only 50. Use of the GAP could be a good method for the detection of GBS in urine specimens from pregnant women. PMID:15297542

  14. Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate

    PubMed Central

    Wang, Xiaoling; Wang, Guoqing; Hao, Mudong

    2015-01-01

    Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick's first law, and Monod's kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates. PMID:26355542

  15. Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate.

    PubMed

    Wang, Xiaoling; Wang, Guoqing; Hao, Mudong

    2015-01-01

    Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick's first law, and Monod's kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates.

  16. A hidden pitfall in the preparation of agar media undermines microorganism cultivability.

    PubMed

    Tanaka, Tomohiro; Kawasaki, Kosei; Daimon, Serina; Kitagawa, Wataru; Yamamoto, Kyosuke; Tamaki, Hideyuki; Tanaka, Michiko; Nakatsu, Cindy H; Kamagata, Yoichi

    2014-12-01

    Microbiologists have been using agar growth medium for over 120 years. It revolutionized microbiology in the 1890s when microbiologists were seeking effective methods to isolate microorganisms, which led to the successful cultivation of microorganisms as single clones. But there has been a disparity between total cell counts and cultivable cell counts on plates, often referred to as the "great plate count anomaly," that has long been a phenomenon that still remains unsolved. Here, we report that a common practice microbiologists have employed to prepare agar medium has a hidden pitfall: when phosphate was autoclaved together with agar to prepare solid growth media (PT medium), total colony counts were remarkably lower than those grown on agar plates in which phosphate and agar were separately autoclaved and mixed right before solidification (PS medium). We used a pure culture of Gemmatimonas aurantiaca T-27(T) and three representative sources of environmental samples, soil, sediment, and water, as inocula and compared colony counts between PT and PS agar plates. There were higher numbers of CFU on PS medium than on PT medium using G. aurantiaca or any of the environmental samples. Chemical analysis of PT agar plates suggested that hydrogen peroxide was contributing to growth inhibition. Comparison of 454 pyrosequences of the environmental samples to the isolates revealed that taxa grown on PS medium were more reflective of the original community structure than those grown on PT medium. Moreover, more hitherto-uncultivated microbes grew on PS than on PT medium.

  17. A Hidden Pitfall in the Preparation of Agar Media Undermines Microorganism Cultivability

    PubMed Central

    Tanaka, Tomohiro; Kawasaki, Kosei; Daimon, Serina; Kitagawa, Wataru; Yamamoto, Kyosuke; Tamaki, Hideyuki; Tanaka, Michiko; Nakatsu, Cindy H.

    2014-01-01

    Microbiologists have been using agar growth medium for over 120 years. It revolutionized microbiology in the 1890s when microbiologists were seeking effective methods to isolate microorganisms, which led to the successful cultivation of microorganisms as single clones. But there has been a disparity between total cell counts and cultivable cell counts on plates, often referred to as the “great plate count anomaly,” that has long been a phenomenon that still remains unsolved. Here, we report that a common practice microbiologists have employed to prepare agar medium has a hidden pitfall: when phosphate was autoclaved together with agar to prepare solid growth media (PT medium), total colony counts were remarkably lower than those grown on agar plates in which phosphate and agar were separately autoclaved and mixed right before solidification (PS medium). We used a pure culture of Gemmatimonas aurantiaca T-27T and three representative sources of environmental samples, soil, sediment, and water, as inocula and compared colony counts between PT and PS agar plates. There were higher numbers of CFU on PS medium than on PT medium using G. aurantiaca or any of the environmental samples. Chemical analysis of PT agar plates suggested that hydrogen peroxide was contributing to growth inhibition. Comparison of 454 pyrosequences of the environmental samples to the isolates revealed that taxa grown on PS medium were more reflective of the original community structure than those grown on PT medium. Moreover, more hitherto-uncultivated microbes grew on PS than on PT medium. PMID:25281372

  18. Proportional smile design using the recurring esthetic dental (red) proportion.

    PubMed

    Ward, D H

    2001-01-01

    Dentists have needed an objective way in which to evaluate a smile. A method for determining the ideal size and position of the anterior teeth has been presented here. Use of the FIVE to evaluate the RED proportion and the width-to-height ratio, tempered with sound clinical judgment, gives pleasing and consistent results. With the diversity that exists in nature, rarely does the final result follow all the mathematical rules of proportional smile design. This approach may serve as a foundation on which to base initial smile design, however. When one begins to understand the relationship between beauty, mathematics, and the surrounding world, one begins to appreciate their interdependence.

  19. Luminescent DNA- and agar-based membranes.

    PubMed

    Leones, R; Fernandes, M; Ferreira, R A S; Cesarino, I; Lima, J F; Carlos, L D; Bermudez, V de Zea; Magon, C J; Donoso, J P; Silva, M M; Pawlicka, A

    2014-09-01

    Luminescent materials containing europium ions are investigated for different optical applications. They can be obtained using bio-macromolecules, which are promising alternatives to synthetic polymers based on the decreasing oil resources. This paper describes studies of the DNA- and Agar-europium triflate luminescent membranes and its potential technological applications are expanded to electroluminescent devices. Polarized optical microscopy demonstrated that the samples are birefringent with submicrometer anisotropy. The X-ray diffraction analysis revealed predominantly amorphous nature of the samples and the atomic force microscopy images showed a roughness of the membranes of 409.0 and 136.1 nm for the samples of DNA10Eu and Agar1.11Eu, respectively. The electron paramagnetic resonance spectra of the DNA(n)Eu membranes with the principal lines at g ≈ 2.0 and g ≈ 4.8 confirmed uniform distribution of rare earth ions in a disordered matrix. Moreover, these strong and narrow resonance lines for the samples of DNA(n)Eu when compared to the Agar(n)Eu suggested a presence of paramagnetic radicals arising from the DNA matrix. The emission spectra suggested that the Eu3+ ions occupy a single local environment in both matrices and the excitation spectra monitored around the Eu emission lines pointed out that the Eu3+ ions in the Agar host were mainly excited via the broad band component rather than by direct intra-4f(6) excitation, whereas the opposite case occurred for the DNA-based sample. PMID:25924317

  20. Low density, microcellular, dopable, agar/gelatin foams for pulsed power experiments

    SciTech Connect

    McNamara, W.F.; Aubert, J.H.

    1997-04-01

    Low-density, microcellular foams prepared from the natural polymers agar and gelatin have been developed for pulsed-power physics experiments. Numerous experiments were supported with foams having densities at or below 10 mg/cm{sup 3}. For some of the experiments, the agar/gelatin foam was uniformly doped with metallic elements using soluble salts. Depending on the method of preparation, cell sizes were typically below 10 microns and for one process were below 1.0 micron.

  1. Keep It in Proportion.

    ERIC Educational Resources Information Center

    Snider, Richard G.

    1985-01-01

    The ratio factors approach involves recognizing a given fraction, then multiplying so that units cancel. This approach, which is grounded in concrete operational thinking patterns, provides a standard for science ratio and proportion problems. Examples are included for unit conversions, mole problems, molarity, speed/density problems, and…

  2. Bayesian inference on proportional elections.

    PubMed

    Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio

    2015-01-01

    Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software.

  3. Bayesian Inference on Proportional Elections

    PubMed Central

    Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio

    2015-01-01

    Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software. PMID:25786259

  4. Evaluation of the chromogenic agar chromID C. difficile.

    PubMed

    Eckert, Catherine; Burghoffer, Béatrice; Lalande, Valérie; Barbut, Frederic

    2013-03-01

    Three selective media (chromID C. difficile agar, taurocholate cycloserine cefoxitin agar [TCCA; homemade], and CLO medium) were compared from 406 stool samples of patients suspected of having Clostridium difficile infection. The sensitivities of chromID C. difficile agar at 24 h and 48 h, CLO medium, and TCCA were 74.1%, 87%, 85.2%, and 70.4%, respectively.

  5. Monitor proportional counter

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.

    1979-01-01

    An Uhuru class Ar-CO2 gas filled proportional counter sealed with a 1.5 mil beryllium window and sensitive to X-rays in the energy bandwidth from 1.5 to 22 keV is presented. This device is coaligned with the X-ray telescope aboard the Einstein Observatory and takes data as a normal part of the Observatory operations.

  6. Agar-Gel Precipitin Technique in Anthrax Antibody Determinations1

    PubMed Central

    Ray, John G.; Kadull, Paul J.

    1964-01-01

    A modification of the agar-gel precipitation inhibition technique of Thorne and Belton for detecting anthrax antibodies reduces inconsistency of visually determined end points on the same sera observed by different technicians. Determination of the minimal reacting concentrations of the anthrax antigen and antibody reagents, modifications of the visualization apparatus, methods for combining reagents, and length of incubation periods contribute to the ease of the end-point determinations and the uniformity of results. When compared with the previous technique, the modified procedure is less time-consuming while retaining satisfactory reproducibility, simplicity, specificity, and sensitivity. Images FIG. 1 FIG. 2 PMID:14201088

  7. Syneresis and delayed detachment in agar plates

    NASA Astrophysics Data System (ADS)

    Divoux, Thibaut; Mao, Bosi; Snabre, Patrick

    Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amount of solvent. These gels undergo spontaneous aging, called syneresis that consists in the shrinkage of the gel matrix and the progressive expulsion of the solvent. As a result, a biogel originally casted in a container often lose contact with the container sidewalls, and the detachment time is a priori difficult to anticipate since it may occur over variable time spans (from hours to days). Here we report on the syneresis phenomena in agar plates that consist in Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analysis allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time $t^*$ is surprisingly not controlled by the mass loss as one would intuitively expect. Instead, $t^*$ is strongly correlated to the gel minimum thickness $e_{min}$ measured along the sidewall of the plate, and increases as a robust function of $e_{min}$ independently of the prior mass-loss history. Time-resolved correlation spectroscopy atypically applied to such weakly diffusive media gives access to the local thinning rate of the gel. This technique also allows us to detect the gel micro-displacements that are triggered by the water evaporation prior to the detachment, and even to anticipate the latter from a few hours. Our work provides observables to predict the detachment time of agar gels in dishes, and highlights the relevance of speckle pattern correlation analysis for the quantitative investigation of the syneresis dynamics in biopolymer gels.

  8. Syneresis and delayed detachment in agar plates.

    PubMed

    Divoux, Thibaut; Mao, Bosi; Snabre, Patrick

    2015-05-14

    Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amounts of solvent. These gels undergo spontaneous aging, called syneresis, which consists of the shrinkage of the gel matrix and the progressive expulsion of solvent. As a result, a biogel originally casted in a container often loses contact with the container sidewalls, and the detachment time is difficult to anticipate a priori, since it may occur over variable time spans (from hours to days). Here we report on syneresis phenomena in agar plates, which consist of Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analysis allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time t* is surprisingly not controlled by the mass loss as one would intuitively expect. Instead, t* is strongly correlated to the gel minimum thickness emin measured along the sidewall of the plate, and increases as a robust function of emin, independently of the prior mass-loss history. Time-resolved correlation spectroscopy atypically applied to such weakly diffusive media gives access to the local thinning rate of the gel. This technique also allows us to detect the gel micro-displacements that are triggered by water evaporation prior to the detachment, and even to anticipate the latter from a few hours. Our work provides observables to predict the detachment time of agar gels in dishes, and highlights the relevance of speckle pattern correlation analysis for the quantitative investigation of the syneresis dynamics in biopolymer gels.

  9. Syneresis and delayed detachment in agar plates.

    PubMed

    Divoux, Thibaut; Mao, Bosi; Snabre, Patrick

    2015-05-14

    Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amounts of solvent. These gels undergo spontaneous aging, called syneresis, which consists of the shrinkage of the gel matrix and the progressive expulsion of solvent. As a result, a biogel originally casted in a container often loses contact with the container sidewalls, and the detachment time is difficult to anticipate a priori, since it may occur over variable time spans (from hours to days). Here we report on syneresis phenomena in agar plates, which consist of Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analysis allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time t* is surprisingly not controlled by the mass loss as one would intuitively expect. Instead, t* is strongly correlated to the gel minimum thickness emin measured along the sidewall of the plate, and increases as a robust function of emin, independently of the prior mass-loss history. Time-resolved correlation spectroscopy atypically applied to such weakly diffusive media gives access to the local thinning rate of the gel. This technique also allows us to detect the gel micro-displacements that are triggered by water evaporation prior to the detachment, and even to anticipate the latter from a few hours. Our work provides observables to predict the detachment time of agar gels in dishes, and highlights the relevance of speckle pattern correlation analysis for the quantitative investigation of the syneresis dynamics in biopolymer gels. PMID:25812667

  10. Characteristic features and dye degrading capability of agar-agar gel immobilized manganese peroxidase.

    PubMed

    Bilal, Muhammad; Asgher, Muhammad; Shahid, Muhammad; Bhatti, Haq Nawaz

    2016-05-01

    Immobilization of enzymes has been regarded as an efficient approach to develop biocatalyst with improved activity and stability characteristics under reaction conditions. In the present study, purified manganese peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized in agar-agar support using entrapment technique. Maximum immobilization yield was accomplished at 4.0% agar-agar gel. The immobilized MnP exhibited better resistance to changes in pH and temperature than the free enzyme, with optimal conditions being pH 6.0 and 50 °C. The kinetic parameters Km and Kcat/Km for free and entrapped MnP were calculated to be 65.6 mM and 6.99 M(-1) s(-1), and 82 mM and 8.15 M(-1) s(-1), respectively. Thermo-stability was significantly improved after immobilization. After 120 h, the insolubilized MnP retained its activity up to 71.9% and 60.3% at 30 °C and 40 °C, respectively. It showed activity until 10th cycle and retained 74.3% residual activity after 3th cycle. The effects of H2O2, ionic strength and potential inhibitors on activity of free and immobilized enzyme were investigated. Moreover, the decolorization of three structurally different dyes was monitored in order to assess the degrading capability of the entrapped MnP. The decolorization efficiencies for all the tested dyes were 78.6-84.7% after 12h. The studies concluded that the toxicity of dyes aqueous solutions was significantly reduced after treatment. The remarkable catalytic, thermo-stability and re-cycling features of the agar-agar immobilized MnP display a high potential for biotechnological applications. PMID:26854887

  11. Xanthan gum: an economical partial substitute for agar in microbial culture media.

    PubMed

    Babbar, Shashi B; Jain, Ruchi

    2006-04-01

    Xanthan gum, microbial desiccation-resistant polysaccharide prepared commercially by aerobic submerged fermentation from Xanthomonas campestris, has been successfully used alone and in combination with agar for microbial culture media. As illustrative examples, eight bacteria and eight fungi were grown on media solidified with either agar (A, 1.5%), xanthan gum (X, 1%), or combinations of both (0.9% X + 0.1% A, 0.8% X + 0.2% A, 0.7% X + 0.3% A, 0.6% X + 0.4% A). All fungi and bacteria exhibited normal growth and differentiation in all these treatments. Rather, growth of most of the fungi was better on xanthan (alone) and xanthan + agar media than agar medium. As the media gelled with xanthan gum alone flow, it was not possible to incubate Petri plates in inverted position. Moreover, because of the softness, streaking of bacteria was difficult on such media. However, these problems could be overcome by partially replacing xanthan gum with 0.3% agar. Bacterial enumeration studies carried out for Serratia sp. and Pseudomonas sp. by serial dilution and pour-plate method on agar (1.5%), 0.7%/0.6% X + 0.3%/0.4% A yielded similar counts. Selective media, succinate medium for Pseudomonas sp., and MacConkey broth medium for Escherichia coli gelled with 0.7%/0.6% X + 0.3%/0.4% A did not support growth of other bacteria when inoculated along with the above-mentioned bacteria. Likewise, differential medium, CRMA (Congo red mannitol agar) gelled with xanthan-agar combination could differentiate between Agrobacterium tumefaciens and Rhizobium sp.

  12. Proportional counter radiation camera

    DOEpatents

    Borkowski, C.J.; Kopp, M.K.

    1974-01-15

    A gas-filled proportional counter camera that images photon emitting sources is described. A two-dimensional, positionsensitive proportional multiwire counter is provided as the detector. The counter consists of a high- voltage anode screen sandwiched between orthogonally disposed planar arrays of multiple parallel strung, resistively coupled cathode wires. Two terminals from each of the cathode arrays are connected to separate timing circuitry to obtain separate X and Y coordinate signal values from pulse shape measurements to define the position of an event within the counter arrays which may be recorded by various means for data display. The counter is further provided with a linear drift field which effectively enlarges the active gas volume of the counter and constrains the recoil electrons produced from ionizing radiation entering the counter to drift perpendicularly toward the planar detection arrays. A collimator is interposed between a subject to be imaged and the counter to transmit only the radiation from the subject which has a perpendicular trajectory with respect to the planar cathode arrays of the detector. (Official Gazette)

  13. Biological treatment of textile dyes by agar-agar immobilized consortium in a packed bed reactor.

    PubMed

    Patel, Yogesh; Gupte, Akshaya

    2015-03-01

    The decolorization of Acid Maroon V was investigated using bacterial consortium EDPA containing Enterobacter dissolvens AGYP1 and Pseudomonas aeruginosa AGYP2 immobilized in different entrapment matrices. The consortium displayed 96% removal of dye (100 mg/l) within 6 h when immobilized in agar-agar. Under optimum concentrations of agar-agar (3.0% w/v) and cell biomass (0.9 g% w/v), the consortium displayed decolorization for 18 successive batches of Acid Maroon V and also decolorized 14 other different textile dyes. A packed bed reactor under batch mode showed 89% decolorization of dye after 56 repetitive cycles. Under continuous flow mode, maximum color removal was achieved with bed length of 36 cm, hydraulic retention time of 2.66 h, and dye concentration of 100 mg/l. Additionally, the reactor decolorized relatively higher concentrations (100-2000 mg/l) of dye. The synthetic dye wastewater containing five textile dyes was decolorized 92% with 62% COD reduction using an immobilized consortium.

  14. Comparison of Fecal Coliform Agar and Violet Red Bile Lactose Agar for Fecal Coliform Enumeration in Foods

    PubMed Central

    Leclercq, A.; Wanegue, C.; Baylac, P.

    2002-01-01

    A 24-h direct plating method for fecal coliform enumeration with a resuscitation step (preincubation for 2 h at 37 ± 1°C and transfer to 44 ± 1°C for 22 h) using fecal coliform agar (FCA) was compared with the 24-h standardized violet red bile lactose agar (VRBL) method. FCA and VRBL have equivalent specificities and sensitivities, except for lactose-positive non-fecal coliforms such as Hafnia alvei, which could form typical colonies on FCA and VRBL. Recovery of cold-stressed Escherichia coli in mashed potatoes on FCA was about 1 log unit lower than that with VRBL. When the FCA method was compared with standard VRBL for enumeration of fecal coliforms, based on counting carried out on 170 different food samples, results were not significantly different (P > 0.05). Based on 203 typical identified colonies selected as found on VRBL and FCA, the latter medium appears to allow the enumeration of more true fecal coliforms and has higher performance in certain ways (specificity, sensitivity, and negative and positive predictive values) than VRBL. Most colonies clearly identified on both media were E. coli and H. alvei, a non-fecal coliform. Therefore, the replacement of fecal coliform enumeration by E. coli enumeration to estimate food sanitary quality should be recommended. PMID:11916678

  15. Recovery of spores of Clostridium botulinum in yeast extract agar and pork infusion agar after heat treatment.

    PubMed

    Odlaug, T E; Pflug, I J

    1977-10-01

    Yeast extract agar, pork infusion agar, and modifications of these media were used to recover heated Clostridium botulinum spores. The D- and z-values were determined. Two type A strains and one type B strain of C. botulinum were studied. In all cases the D-values were largest when the spores were recovered in yeast extract agar, compared to the D-values for spores recovered in pork infusion agar. The z-values for strains 62A and A16037 were largest when the spores were recovered in pork infusion agar. The addition of sodium bicarbonate and sodium thioglycolate to pork infusion agar resulted in D-values for C. botulinum 62A spores similar to those for the same spores recovered in yeast extract agar. The results suggest that sodium bicarbonate and sodium thioglycolate should be added to recovery media for heated C. botulinum spores to obtain maximum plate counts. PMID:335970

  16. Masked Proportional Routing

    NASA Technical Reports Server (NTRS)

    Wolpert, David

    2004-01-01

    Masked proportional routing is an improved procedure for choosing links between adjacent nodes of a network for the purpose of transporting an entity from a source node ("A") to a destination node ("B"). The entity could be, for example, a physical object to be shipped, in which case the nodes would represent waypoints and the links would represent roads or other paths between waypoints. For another example, the entity could be a message or packet of data to be transmitted from A to B, in which case the nodes could be computer-controlled switching stations and the links could be communication channels between the stations. In yet another example, an entity could represent a workpiece while links and nodes could represent, respectively, manufacturing processes and stages in the progress of the workpiece towards a finished product. More generally, the nodes could represent states of an entity and the links could represent allowed transitions of the entity. The purpose of masked proportional routing and of related prior routing procedures is to schedule transitions of entities from their initial states ("A") to their final states ("B") in such a manner as to minimize a cost or to attain some other measure of optimality or efficiency. Masked proportional routing follows a distributed (in the sense of decentralized) approach to probabilistically or deterministically choosing the links. It was developed to satisfy a need for a routing procedure that 1. Does not always choose the same link(s), even for two instances characterized by identical estimated values of associated cost functions; 2. Enables a graceful transition from one set of links to another set of links as the circumstances of operation of the network change over time; 3. Is preferably amenable to separate optimization of different portions of the network; 4. Is preferably usable in a network in which some of the routing decisions are made by one or more other procedure(s); 5. Preferably does not cause an

  17. Gated strip proportional detector

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    1987-01-01

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  18. Gated strip proportional detector

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1985-02-19

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  19. Improving agar electrospinnability with choline-based deep eutectic solvents.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

    2015-09-01

    Very recently our group has produced novel agar-based fibers by an electrospinning technique using water as solvent and polyvinyl alcohol (PVA) as co-blending polymer. Here, we tested the deep eutectic solvent (DES), (2-hydroxyethyl)trimethylammonium chloride/urea prepared at 1:2 molar ratio, as an alternative solvent medium for agar electrospinning. The electrospun materials were collected with an ethanol bath adapted to a previous electrospinning set-up. One weight percent agar-in-DES showed improved viscoelasticity and hence, spinnability, when compared to 1 wt% agar-in-water and pure agar nanofibers were successfully electrospun if working above the temperature of sol-gel transition (∼80 °C). By changing the solvent medium we decreased the PVA concentration (5 wt% starting solution) and successfully produced composite fibers with high agar contents (50/50 agar/PVA). Best composite fibers were formed with the 50/50 and 30/70 agar/PVA solutions. These fibers were mechanically resistant, showed tailorable surface roughness and diverse size distributions, with most of the diameters falling in the sub-micron range. Both nano and micro forms of agar fibers (used separately or combined) may have potential for the design of new and highly functional agar-based materials. PMID:26116384

  20. Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.

    PubMed

    Laarhoven, Bob; Elissen, H J H; Temmink, H; Buisman, C J N

    2016-01-01

    An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates.

  1. Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus

    PubMed Central

    Laarhoven, Bob; Elissen, H. J. H.; Temmink, H.; Buisman, C. J. N.

    2016-01-01

    An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates. PMID:26937632

  2. Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.

    PubMed

    Laarhoven, Bob; Elissen, H J H; Temmink, H; Buisman, C J N

    2016-01-01

    An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates. PMID:26937632

  3. Performance of CHROMAGAR candida and BIGGY agar for identification of yeast species

    PubMed Central

    Yücesoy, Mine; Marol, Serhat

    2003-01-01

    Background The importance of identifying the pathogenic fungi rapidly has encouraged the development of differential media for the presumptive identification of yeasts. In this study two differential media, CHROMagar Candida and bismuth sulphite glucose glycine yeast agar, were evaluated for the presumptive identification of yeast species. Methods A total number of 270 yeast strains including 169 Candida albicans, 33 C. tropicalis, 24 C. glabrata, 18 C. parapsilosis, 12 C. krusei, 5 Trichosporon spp., 4 C. kefyr, 2 C. lusitaniae, 1 Saccharomyces cerevisiae and 1 Geotrichum candidum were included. The strains were first identified by germ tube test, morphological characteristics on cornmeal tween 80 agar and Vitek 32 and API 20 C AUX systems. In parallel, they were also streaked onto CHROMagar Candida and bismuth sulphite glucose glycine yeast agar plates. The results were read according to the color, morphology of the colonies and the existance of halo around them after 48 hours of incubation at 37°C. Results The sensitivity and specificity values for C. albicans strains were found to be 99.4, 100% for CHROMagar Candida and 87.0, 75.2% for BiGGY agar, respectively. The sensitivity of CHROMagar Candida to identify C. tropicalis, C. glabrata and C. krusei ranged between 90.9 and 100% while the specificity was 100%. The sensitivity rates for BiGGY agar were 66.6 and 100% while the specificity values were found to be 95.4 and 100% for C. tropicalis and C. krusei, respectively. Conclusions It can be concluded that the use of CHROMagar Candida is an easy and reliable method for the presumptive identification of most commonly isolated Candida species especially C. albicans, C. tropicalis and C. krusei. The lower sensitivity and specificity of BiGGY agar to identify commonly isolated Candida species potentially limits the clinical usefulness of this agar. PMID:14613587

  4. Determination of the isomeric forms proportion of fluorogenic naphthalene-2,3-dicarboxaldehyde in a binary mixture of water:methanol using electrochemical methods.

    PubMed

    Faure, Mathilde; Le Potier, Isabelle; Pallandre, Antoine; Chebil, Syrine; Haghiri-Gosnet, Anne-Marie; Deslouis, Claude; Maisonhaute, Emmanuel; Gamby, Jean

    2016-02-01

    The electrochemical response of the fluorogenic label naphthalene-2,3-dicarboxyaldehyde (NDA) in a binary mixture of water/methanol was characterized with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) electrochemical techniques. Naphthalene-2,3-dicarboxyaldehyde does exist in three isomeric forms in aqueous solution: the unhydrated dialdehyde (DA), the acyclic monohydrated (MA) and the cyclic hemiacetal (HAC). The study underlines that the proportion of each of them varies according to the working pH. At low and high pH, the dialdehyde form is in larger proportion than the acyclic monohydrated form. Conversely at intermediate pH, the concentration of the acyclic form is in greater proportion than the dialdehyde form. These results allowed us to determine the optimal pH of 9 for which the labeling of biomolecules could be more efficient due to the base catalyzed regeneration of the unhydrated form. At this pH, the data processing from the analysis of measured currents and estimation of diffusion coefficients of each form according to the semi-empirical models of Wilke-Chang, Scheibel, Reddy-Doraiswamy and Lusis-Ratcliff allowed us to obtain the concentration of dialdehyde (0.28 mM), acyclic monohydrated (0.57 mM) and cyclic hemiacetal monohydrated (0.15 mM) forms starting from 1mM naphthalene-2,3-dicarboxyaldehyde.

  5. Trace Amounts of Furan-2-Carboxylic Acids Determine the Quality of Solid Agar Plates for Bacterial Culture

    PubMed Central

    Hara, Shintaro; Isoda, Reika; Tahvanainen, Teemu; Hashidoko, Yasuyuki

    2012-01-01

    Background Many investigators have recognised that a significant proportion of environmental bacteria exist in a viable but non-culturable state on agar plates, and some researchers have also noticed that some of such bacteria clearly recover their growth on matrices other than agar. However, the reason why agar is unsuitable for the growth of some bacteria has not been addressed. Methodology/Principal Findings According to the guide of a bioassay for swarming inhibition, we identified 5-hydroxymethylfuran-2-carboxylic acid (5-HMFA) and furan-2-carboxylic acid (FA) as factors that inhibit bacterial swarming and likely inhibit extracellular polysaccharide production on agar. The furan-2-carboxylic acids 5-HMFA and FA effectively inhibited the swarming and swimming of several environmental bacteria at concentrations of 1.8 and 2.3 µg L−1 (13 and 21 nmol L−1), respectively, which are equivalent to the concentrations of these compounds in 0.3% agar. On Luria-Bertani (LB) plates containing 1.0% agar that had been previously washed with MeOH, a mixture of 5-HMFA and FA in amounts equivalent to their original concentrations in the unwashed agar repressed the swarming of Escherichia coli K12 strain W3110, a representative swarming bacterium. Conclusions/Significance Agar that contains trace amounts of 5-HMFA and FA inhibits the proliferation of some slow-growing or difficult-to-culture bacteria on the plates, but it is useful for single colony isolation due to the ease of identification of swarmable bacteria as the non-swarmed colonies. PMID:22848437

  6. AgarTrap-mediated genetic transformation using intact gemmae/gemmalings of the liverwort Marchantia polymorpha L.

    PubMed

    Tsuboyama-Tanaka, Shoko; Kodama, Yutaka

    2015-03-01

    The dioecious liverwort, Marchantia polymorpha L., is an emerging model plant. Various molecular biological techniques have been optimized for M. polymorpha for the past several years, and recently we reported a simplified Agrobacterium-mediated transformation method using sporelings (immature thalli from spores) of M. polymorpha. This method, termed AgarTrap (Agar-utilized Transformation with Pouring Solutions), completed by exchanging appropriate solutions on a single Petri dish to produce a sufficient number of independent transgenic sporelings. However, because spores are produced by crosses between males and females, the genetic backgrounds of resulting transgenic sporelings are not uniform. To easily produce transgenic liverworts with a uniform genetic background using AgarTrap, we developed an AgarTrap-mediated transformation method using intact gemmae/gemmalings produced by asexual reproduction. Using AgarTrap with male and female gemmae/gemmalings produced a sufficient number of independent transgenic gemmalings with uniform genetic backgrounds. The optimized transformation efficiencies were approximately 30 and 50 % in males and females, respectively. As with AgarTrap using sporelings, AgarTrap using intact gemmae/gemmalings will be useful in promoting studies of the molecular biology of M. polymorpha. PMID:25663453

  7. Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.

    PubMed

    Kanmani, Paulraj; Rhim, Jong-Whan

    2014-02-15

    The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 μg/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food. PMID:24507339

  8. Preparation and characterization of agar/clay nanocomposite films: the effect of clay type.

    PubMed

    Rhim, Jong-Whan; Lee, Soo-Bin; Hong, Seok-In

    2011-04-01

    Agar-based nanocomposite films with different types of nanoclays, such as Cloisite Na+, Cloisite 30B, and Cloisite 20A, were prepared using a solvent casting method, and their tensile, water vapor barrier, and antimicrobial properties were tested. Tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of control agar film were 29.7±1.7 MPa, 45.3±9.6%, and (2.22±0.19)×10(-9) g·m/m2·s·Pa, respectively. All the film properties tested, including transmittance, tensile properties, WVP, and X-ray diffraction patterns, indicated that Cloisite Na+ was the most compatible with agar matrix. TS of the nanocomposite films prepared with 5% Cloisite Na+ increased by 18%, while WVP of the nanocomposite films decreased by 24% through nanoclay compounding. Among the agar/clay nanocomposite films tested, only agar/Cloisite 30B nanocomposite film showed a bacteriostatic function against Listeria monocytogenes.

  9. DETECTORS AND EXPERIMENTAL METHODS: Study of a multi-wire proportional chamber with a cathode strip and delay-line readout

    NASA Astrophysics Data System (ADS)

    Han, Li-Ying; Li, Qi-Te; Faisal, Q.; Ge, Yu-Cheng; Liu, Hong-Tao; Ye, Yan-Lin

    2009-05-01

    The design principle for a multi-wire proportional chamber with a cathode strip and delay-line readout is described. A prototype chamber of a size of 10 cm ×10 cm was made together with the readout electronics circuit. A very clean signal with very low background noise was obtained by applying a transformer between the delay-line and the pre-amplifier in order to match the resistance. Along the anode wire direction a position resolution of less than 0.5 mm was achieved with a 55Fe-5.9 keV X ray source. The simple structure, large effective area and high position resolution allow the application of a gas chamber of this kind to many purposes.

  10. [Presumptive identification of Candida spp. and other clinically important yeasts: usefulness of Brilliance Candida Agar].

    PubMed

    Alfonso, Claudia; López, Mónica; Arechavala, Alicia; Perrone, María Del Carmen; Guelfand, Liliana; Bianchi, Mario

    2010-06-30

    Fungal infections caused by yeasts have increased during the last decades and invasive forms represent a serious problem for human health. Candida albicans is the species most frequently isolated from clinical samples. However, other emerging yeast pathogens are increasingly responsible for mycotic infections, and some of them are resistant to some antifungal drugs. Consequently, it is necessary to have methods that can provide a rapid presumptive identification at species level. Numerous chromogenic agar media have been shown to be of value as diagnostic tools. We have compared a chromogenic medium, Brilliance Candida Agar, with CHROMagar Candida, the chromogenic medium most used in our country. A multicentre study was conducted in 16 Hospitals belonging to the Mycology Net of Buenos Aires City Government. A total of 240 yeast isolates were included in this research. The new chromogenic agar showed results very similar to those obtained with CHROMagar Candida.

  11. Removal of 2,4-dinitrotoluene from concrete using bioremediation, agar extraction, and photocatalysis.

    PubMed

    Phutane, S R; Renner, J N; Nelson, S L; Seames, W S; Páca, J; Sundstrom, T J; Kozliak, E I

    2007-01-01

    Three methods, i.e. bioremediation by application of bacteria-laden agar, physical absorption of DNT by agar, or illumination by UV light were evaluated for the removal of 2,4-dinitrotoluene (DNT) from building-grade concrete. DNT biodegradation by Pseudomonas putida TOD was turned "on" and "off" by using toluene as a co-substrate thus allowing for rate-limiting step assessment. Bioremediation efficiency can be > 95-97% in 5-7 d if the process occurs at optimum growth temperature with the biological processes appearing to be rate-limiting. Sterile agar can remove up to 80% of DNT from concrete thus allowing DNT desorption and biodegradation to be conducted separately. Photoremediation results in 50% DNT removal in 9-12 d with no further removal, most likely due to mass transfer limitations.

  12. Homogeneous Matrix Deposition on Dried Agar for MALDI Imaging Mass Spectrometry of Microbial Cultures

    NASA Astrophysics Data System (ADS)

    Hoffmann, Thomas; Dorrestein, Pieter C.

    2015-11-01

    Matrix deposition on agar-based microbial colonies for MALDI imaging mass spectrometry is often complicated by the complex media on which microbes are grown. This Application Note demonstrates how consecutive short spray pulses of a matrix solution can form an evenly closed matrix layer on dried agar. Compared with sieving dry matrix onto wet agar, this method supports analyte cocrystallization, which results in significantly more signals, higher signal-to-noise ratios, and improved ionization efficiency. The even matrix layer improves spot-to-spot precision of measured m/z values when using TOF mass spectrometers. With this technique, we established reproducible imaging mass spectrometry of myxobacterial cultures on nutrient-rich cultivation media, which was not possible with the sieving technique.

  13. Visual Manipulatives for Proportional Reasoning.

    ERIC Educational Resources Information Center

    Moore, Joyce L.; Schwartz, Daniel L.

    The use of a visual representation in learning about proportional relations was studied, examining students' understandings of the invariance of a multiplicative relation on both sides of a proportion equation and the invariance of the structural relations that exist in different semantic types of proportion problems. Subjects were 49 high-ability…

  14. Assessment of Etest as an alternative to agar dilution for antimicrobial susceptibility testing of Neisseria gonorrhoeae.

    PubMed

    Liu, Hsi; Taylor, Thomas H; Pettus, Kevin; Trees, David

    2014-05-01

    We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest.

  15. Incisors’ proportions in smile esthetics

    PubMed Central

    Alsulaimani, Fahad F; Batwa, Waeil

    2013-01-01

    Aims: To determine whether alteration of the maxillary central and lateral incisors’ length and width, respectively, would affect perceived smile esthetics and to validate the most esthetic length and width, respectively, for the central and lateral incisors. Materials and Methods: Photographic manipulation was undertaken to produce two sets of photographs, each set of four photographs showing the altered width of the lateral incisor and length of the central length. The eight produced photographs were assessed by laypeople, dentists and orthodontists. Results: Alteration in the incisors’ proportion affected the relative smile attractiveness for laypeople (n=124), dentists (n=115) and orthodontists (n=68); dentists and orthodontists did not accept lateral width reduction of more than 0.5 mm (P<0.01), which suggests that the lateral to central incisor width ratio ranges from 54% to 62%. However, laypeople did not accept lateral width reduction of more than 1 mm (P<0.01), widening the range to be from 48% to 62%. All groups had zero tolerance for changes in central crown length (P<0.01). Conclusion: All participants recognized that the central incisors’ length changes. For lateral incisors, laypeople were more tolerant than dentists and orthodontists. This suggests that changing incisors’ proportions affects the relative smile attractiveness. PMID:24987650

  16. Comparison of inhibitory mold agar to Sabouraud dextrose agar as a primary medium for isolation of fungi.

    PubMed

    Scognamiglio, Theresa; Zinchuk, Riva; Gumpeni, Pramod; Larone, Davise H

    2010-05-01

    Clinical specimens cultured on two selective fungal media, inhibitory mold agar (IMA) and Sabouraud dextrose agar (SDA), were compared with respect to recovery of fungi. Of the 840 fungal isolates recovered, 69.3% grew on both IMA and SDA; 24.9% grew only on IMA; and 5.8% grew only on SDA, showing that IMA is superior (P=0.003).

  17. Using Resampling to Compare Two Proportions

    ERIC Educational Resources Information Center

    Stephenson, W. Robert; Froelich, Amy G.; Duckworth, William M.

    2010-01-01

    This article shows that when applying resampling methods to the problem of comparing two proportions, students can discover that whether you resample with or without replacement can make a big difference.

  18. A new method to evaluate the effects of bacterial dosage, infection route and Vibrio strain in experimental challenges of Litopenaeus vannamei, based on the Cox proportional hazard model.

    PubMed

    Xia, Qing; Wang, Baojie; Liu, Mei; Jiang, Keyong; Wang, Lei

    2015-10-01

    In the shrimp challenge test the Vibrio dosage, infection route, and strain are considered as risk factors that result in mortality. Assessment of Vibrio/shrimp interactions, and disease dynamics following infection by Vibrio, are useful techniques needed for detailed studies on the control of risk factors. In this paper we used an application of the Cox proportional hazard model to assess relative survival probability, estimate mortality risk, and construct a prognostic model to assess predictions of estimated time to death. Results indicate that infection route was the most important prognostic factor contributing to mortality in the challenge test (β = 3.698, P < 0.000). The shrimp infection rate following injection was found to be 40.4 times greater than that following immersion (hazard ratio (HR) = 40.4; p = 0.000). Our results also indicated that the HR resulting in shrimp mortality following a high dose of 10(8) cfu/shrimp was significantly greater (HR = 5.9, P < 0.000), than that following a baseline dosage of 10(7) cfu/shrimp. Strain Vh was found to be more virulent than Strain Vp (HR = 4.8; P < 0.000). The prognostic index also indicated that the infection route is the most important prognostic factor contributing to mortality in the challenge test.

  19. Electrophoretic method for the determination of the proportion of gamma-aminobutyric acid in a mixture of labeled neurotransmitter and its catabolites

    SciTech Connect

    Cupello, A.; Rapallino, M.V.; Besio, G.; Mainardi, P.

    1987-01-01

    An electrophoretic method for the separation of gamma-aminobutyric acid (GABA) from its metabolites after GABA-transaminase attack is presented. The method is based on the fact that at neutral pH GABA has no net electrical charge, whereas its major metabolites, succinic acid and Krebs cycle intermediates, are negatively charged. The method appears to be especially suitable for evaluation of true-labeled neurotransmitter within the radioactivity which is found in synaptosomes after labeled GABA-uptake studies.

  20. Evaluation of Bio-Rad MRSASelect agar for detection of methicillin-resistant Staphylococcus aureus directly from blood cultures.

    PubMed

    Riedel, Stefan; Dam, Lisa; Stamper, Paul D; Shah, Syed A R; Carroll, Karen C

    2010-06-01

    MRSASelect agar (Bio-Rad, Redmond, WA) was evaluated for its performance in detecting MRSA directly from positive blood cultures containing Gram-positive cocci in clusters. Agar plates were evaluated for the presence of pink colonies at 18 to 24 h. Results were compared to organism identification by using standard laboratory methods. Confirming coagulase on pink isolates, the sensitivity and specificity were both 99%.

  1. Direct Protocol for Ambient Mass Spectrometry Imaging on Agar Culture.

    PubMed

    Angolini, Célio Fernando F; Vendramini, Pedro Henrique; Araújo, Francisca D S; Araújo, Welington L; Augusti, Rodinei; Eberlin, Marcos N; de Oliveira, Luciana Gonzaga

    2015-07-01

    Herein we describe a new protocol that allows direct mass spectrometry imaging (IMS) of agar cultures. A simple sample dehydration leads to a thin solid agar, which enables the direct use of spray-based ambient mass spectrometry techniques. To demonstrate its applicability, metal scavengers siderophores were imaged directly from agar culture of S. wadayamensis, and well resolved and intense images were obtained using both desorption electrospray ionization (DESI) and easy ambient sonic-spray ionization (EASI) with well-defined selective spatial distributions for the free and the metal-bound molecules, providing clues for their roles in cellular metabolism.

  2. Comparative evaluation of chromogenic agar medium and conventional culture system for isolation and presumptive identification of uropathogens

    PubMed Central

    Akter, Laila; Haque, Rezwana; Salam, Md. Abdus

    2014-01-01

    Objective: Urine is the most frequent specimen received for culture/sensitivity by clinical laboratories. The microbiological performance of HiCrome UTI agar medium was compared with Blood agar and MacConkey agar for isolation and presumptive identification of bacteria from urine culture. Methods: A total of 443 consecutively collected midstream and/or catheter-catch urine samples from patients attending the Islami Bank Medical College Hospital, Rajshahi, Bangladesh during January to December, 2012 were cultured. Urine samples showing pus cells ≥ 5/HPF were inoculated on to Blood agar (BA), MacConkey agar (MAC) and HiCrome UTI agar (CA) media simultaneously and incubated overnight aerobically at 370C. Rate of isolation and presumptive identification of bacterial species were compared for different media. Results: Culture yielded a total of 199 bacterial isolates from 189 (42.67%) positive plates including 179 (40.40%) unimicrobial and 10 (2.26%) polymicrobial (mixed growth of pair of bacteria) growths. Both HiCrome UTI agar and Blood agar media supported 100% growths while 151 (75.88%) growths were observed on MacConkey agar. The rate of presumptive identification was found significantly higher on HiCrome UTI agar (97.49%) than MAC agar (67.34%) (P<0.001) as primary urine culture medium. Of 199 isolates, E. coli was found to be the leading uropathogen isolated from 118 (59.30%) samples with its presumptive identification rate of 95.76%, 93.22% and 5.93% on CA, MAC and BA respectively. All 10 (100%) polymicrobial growths were demonstrated distinctly on CA against only 01(10%) on each BA and MAC. Conclusion: HiCrome UTI agar was found to be more useful as primary urine culture medium in both higher rate of isolation and presumptive identification of uropathogens in comparison to conventional media. Its inherent characteristics in demonstrating polymicrobial growth and ease of rapid identification by distinct colony colour are unique. PMID:25225521

  3. Evaluation and interlaboratory validation of a selective agar for phosphatidylinositol-specific phospholipase C activity using a chromogenic substrate to detect Listeria monocytogenes from foods.

    PubMed

    Jinneman, Karen C; Hunt, Jan M; Eklund, Cheryl A; Wernberg, Jane S; Sado, Patricia N; Johnson, Janelle M; Richter, Richelle S; Torres, Selene T; Ayotte, Eugene; Eliasberg, Stacey J; Istafanos, Phillip; Bass, Deborah; Kexel-Calabresa, Nancy; Lin, Wen; Barton, Curtis N

    2003-03-01

    Phosphatidylinositol-specific phospholipase C (PI-PLC) activity is a potential virulence factor and is exhibited only by the Listeria species Listeria monocytogenes and Listeria ivanovii. A chromogenic substrate for the direct detection of PI-PLC activity is available in a new medium (BCM L. monocytogenes plating agar). The use of a chromogenic substrate offers a mechanism with which to directly screen for L. monocytogenes and L. ivanovii other than the esculin used in Oxford (OXF) and Palcam (PAL) agars, which screen for all Listeria species. The specificity levels of BCM plating agar and of BCM confirmation and rhamnose agars were evaluated with 107 Listeria and 10 Bacillus species isolates. In addition, BCM L. monocytogenes plating agar was compared with standard Listeria selective agars (OXF and PAL agars) with regard to the recovery of L. monocytogenes from 2,000 food and environmental samples obtained from eight participating laboratories. A Listeria species was isolated from at least one of the agars in 209 analyses, and L. monocytogenes was isolated in 135 of these analyses. In 27 of the analyses in which L. monocytogenes was isolated, one or more of the selective differential agars used failed to isolate L. monocytogenes, and therefore the results of these analyses were discrepant. Relative to a reference method involving the use of all three agars (OXF, PAL, and BCM agars), the OXF-BCM, PAL-BCM, and OXF-PAL combinations had sensitivities of 99.3, 99.2, and 90.2%, respectively. In statistical analyses of the different combinations of agars, the OXF-BCM and BCM-PAL combinations were found to be superior to the OXF-PAL combination for the detection of L. monocytogenes.

  4. Preparation of an agar-silver nanoparticles (A-AgNp) film for increasing the shelf-life of fruits.

    PubMed

    Gudadhe, Janhavi A; Yadav, Alka; Gade, Aniket; Marcato, Priscyla D; Durán, Nelson; Rai, Mahendra

    2014-12-01

    Preparation of protective coating possessing antimicrobial properties is present day need as they increase the shelf life of fruits and vegetables. In the present study, preparation of agar-silver nanoparticle film for increasing the shelf life of fruits is reported. Silver nanoparticles (Ag-NPs) biosynthesised using an extract of Ocimum sanctum leaves, were mixed with agar-agar to prepare an agar-silver nanoparticles (A-AgNp) film. This film was surface-coated over the fruits, Citrus aurantifolium (Thornless lime) and Pyrus malus (Apple), and evaluated for the determination of antimicrobial activity of A-AgNp films using disc diffusion method, weight loss and shelf life of fruits. This study demonstrates that these A-AgNp films possess antimicrobial activity and also increase the shelf life of fruits. PMID:25429496

  5. The performance of different propensity-score methods for estimating differences in proportions (risk differences or absolute risk reductions) in observational studies.

    PubMed

    Austin, Peter C

    2010-09-10

    Propensity score methods are increasingly being used to estimate the effects of treatments on health outcomes using observational data. There are four methods for using the propensity score to estimate treatment effects: covariate adjustment using the propensity score, stratification on the propensity score, propensity-score matching, and inverse probability of treatment weighting (IPTW) using the propensity score. When outcomes are binary, the effect of treatment on the outcome can be described using odds ratios, relative risks, risk differences, or the number needed to treat. Several clinical commentators suggested that risk differences and numbers needed to treat are more meaningful for clinical decision making than are odds ratios or relative risks. However, there is a paucity of information about the relative performance of the different propensity-score methods for estimating risk differences. We conducted a series of Monte Carlo simulations to examine this issue. We examined bias, variance estimation, coverage of confidence intervals, mean-squared error (MSE), and type I error rates. A doubly robust version of IPTW had superior performance compared with the other propensity-score methods. It resulted in unbiased estimation of risk differences, treatment effects with the lowest standard errors, confidence intervals with the correct coverage rates, and correct type I error rates. Stratification, matching on the propensity score, and covariate adjustment using the propensity score resulted in minor to modest bias in estimating risk differences. Estimators based on IPTW had lower MSE compared with other propensity-score methods. Differences between IPTW and propensity-score matching may reflect that these two methods estimate the average treatment effect and the average treatment effect for the treated, respectively.

  6. Automated counting of bacterial colony forming units on agar plates.

    PubMed

    Brugger, Silvio D; Baumberger, Christian; Jost, Marcel; Jenni, Werner; Brugger, Urs; Mühlemann, Kathrin

    2012-01-01

    Manual counting of bacterial colony forming units (CFUs) on agar plates is laborious and error-prone. We therefore implemented a colony counting system with a novel segmentation algorithm to discriminate bacterial colonies from blood and other agar plates.A colony counter hardware was designed and a novel segmentation algorithm was written in MATLAB. In brief, pre-processing with Top-Hat-filtering to obtain a uniform background was followed by the segmentation step, during which the colony images were extracted from the blood agar and individual colonies were separated. A Bayes classifier was then applied to count the final number of bacterial colonies as some of the colonies could still be concatenated to form larger groups. To assess accuracy and performance of the colony counter, we tested automated colony counting of different agar plates with known CFU numbers of S. pneumoniae, P. aeruginosa and M. catarrhalis and showed excellent performance.

  7. An Optimized Trichloroacetic Acid/Acetone Precipitation Method for Two-Dimensional Gel Electrophoresis Analysis of Qinchuan Cattle Longissimus Dorsi Muscle Containing High Proportion of Marbling.

    PubMed

    Hao, Ruijie; Adoligbe, Camus; Jiang, Bijie; Zhao, Xianlin; Gui, Linsheng; Qu, Kaixing; Wu, Sen; Zan, Linsen

    2015-01-01

    Longissimus dorsi muscle (LD) proteomics provides a novel opportunity to reveal the molecular mechanism behind intramuscular fat deposition. Unfortunately, the vast amounts of lipids and nucleic acids in this tissue hampered LD proteomics analysis. Trichloroacetic acid (TCA)/acetone precipitation is a widely used method to remove contaminants from protein samples. However, the high speed centrifugation employed in this method produces hard precipitates, which restrict contaminant elimination and protein re-dissolution. To address the problem, the centrifugation precipitates were first grinded with a glass tissue grinder and then washed with 90% acetone (TCA/acetone-G-W) in the present study. According to our result, the treatment for solid precipitate facilitated non-protein contaminant removal and protein re-dissolution, ultimately improving two-dimensional gel electrophoresis (2-DE) analysis. Additionally, we also evaluated the effect of sample drying on 2-DE profile as well as protein yield. It was found that 30 min air-drying did not result in significant protein loss, but reduced horizontal streaking and smearing on 2-DE gel compared to 10 min. In summary, we developed an optimized TCA/acetone precipitation method for protein extraction of LD, in which the modifications improved the effectiveness of TCA/acetone method.

  8. [Evaluation of blood agar medium for the growth of mycobacteria].

    PubMed

    Coban, Ahmet Yılmaz; Akgüneş, Alper; Durupınar, Belma

    2011-10-01

    This study was aimed to evaluate the performance of blood agar for the growth of mycobacteria from clinical specimens sent to Mycobacteriology Laboratory of Samsun Chest Diseases Hospital. One hundred fifty six clinical specimens including 123 sputum, 28 bronchoalveolar lavage (BAL) and 5 pleural fluid specimens were inoculated in Löwenstein-Jensen (LJ), BACTEC MGIT 960 system (Becton Dickinson, USA) and blood agar following decontamination process. The specimens were also simultaneously examined for the presence of acid-fast bacilli (AFB). Thirty five mycobacteria strains (33 Mycobacterium tuberculosis and 2 atypical mycobacteria) grew in blood agar, 38 (36 M.tuberculosis and 2 atypical mycobacteria) in LJ media and 46 (44 M.tuberculosis and 2 atypical mycobacteria) in BACTEC MGIT 960 system. Among 29 AFB negative specimens, 20 revealed growth in both blood agar and LJ medium and 27 in MGIT system. AFB positive 20 samples yielded growth in 15 samples in blood agar, 18 in LJ medium and 19 in MGIT system. Among the total of 156 samples, contamination was observed in 15 (9.6%) samples in blood agar, 16 (10.2%) in LJ medium and 18 (11.5%) in MGIT system. Growth time was 5-35 days (mean 18 ± 7.4), 11-35 days (mean 19 ± 5.9) and 5-15 days (mean 10 ± 2.4) for blood agar, LJ medium and BACTEC MGIT 960 system, respectively. The three samples which revealed contamination in BACTEC MGIT 960 system, grew successfully in both blood agar and LJ medium without contamination. In one sample, growth was observed only in LJ medium but neither in blood agar nor BACTEC MGIT 960 system. However, in another sample, growth was observed only in blood agar while no growth was detected in LJ or BACTEC MGIT 960 system. Six samples yielded mycobacteria only in BACTEC MGIT 960 system. These results indicated that simultaneous use of one liquid and one solid medium to grow mycobacteria from the clinical samples seemed to be complementary. Blood agar was a promising choice since it was found

  9. Use of Mueller-Hinton broth and agar in the germ tube test.

    PubMed

    Mattei, Antonella Souza; Alves, Sydney Hartz; Severo, Cecília Bittencourt; Guazzelli, Luciana da Silva; Oliveira, Flávio de Mattos; Severo, Luiz Carlos

    2014-01-01

    Candida albicans is often isolated from clinical samples, thus its presumptive differentiation from other species of the same genus can be based on its ability to form the germ tube in human serum. Nevertheless, there are two other species that share this characteristic: C. dubliniensis and C. africana. The aim of this study was to compare four different substrates to perform the germ tube (GT) test. The Candida spp. isolates were identified using a manual system (135 C. albicans, 24 C. tropicalis and one C. dubliniensis). The germ tube test was performed with fresh, previously frozen serum and Mueller-Hinton (MH) broth and agar. GT was observed in 96% (130/136) of the isolates through the fresh serum technique, 94% (128/136) through previously frozen serum, 92% (125/136) in MH agar, and 90% (122/136) in MH broth. The sensitivity of each test was higher than 90%, with 100% specificity. Both the MH agar and broth were able to identify the true positives, and false positives were not found. However, some C. albicans isolates were not identified. MH agar and broth may be used in laboratory for the rapid presumptive identification of C. albicans, as an alternative method for germ tube test.

  10. Hyperspectral image reconstruction using RGB color for foodborne pathogen detection on agar plates

    NASA Astrophysics Data System (ADS)

    Yoon, Seung-Chul; Shin, Tae-Sung; Park, Bosoon; Lawrence, Kurt C.; Heitschmidt, Gerald W.

    2014-03-01

    This paper reports the latest development of a color vision technique for detecting colonies of foodborne pathogens grown on agar plates with a hyperspectral image classification model that was developed using full hyperspectral data. The hyperspectral classification model depended on reflectance spectra measured in the visible and near-infrared spectral range from 400 and 1,000 nm (473 narrow spectral bands). Multivariate regression methods were used to estimate and predict hyperspectral data from RGB color values. The six representative non-O157 Shiga-toxin producing Eschetichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) were grown on Rainbow agar plates. A line-scan pushbroom hyperspectral image sensor was used to scan 36 agar plates grown with pure STEC colonies at each plate. The 36 hyperspectral images of the agar plates were divided in half to create training and test sets. The mean Rsquared value for hyperspectral image estimation was about 0.98 in the spectral range between 400 and 700 nm for linear, quadratic and cubic polynomial regression models and the detection accuracy of the hyperspectral image classification model with the principal component analysis and k-nearest neighbors for the test set was up to 92% (99% with the original hyperspectral images). Thus, the results of the study suggested that color-based detection may be viable as a multispectral imaging solution without much loss of prediction accuracy compared to hyperspectral imaging.

  11. Use of Dehydrated Agar to Estimate Microbial Water Quality for Horticulture Irrigation.

    PubMed

    Meador, Dustin P; Fisher, Paul R; Guy, Charles L; Harmon, Philip F; Peres, Natalia A; Teplitski, Max

    2016-07-01

    Petrifilms are dehydrated agar culture plates that have been used to quantify colony forming units (CFU) mL of either aerobic bacteria (Petrifilm-AC) or fungus (Petrifilm-YM), depending on substrate composition. Microbes in irrigation systems can indicate biofilm risk and potential clogging of irrigation emitters. The research objective was to compare counts on Petrifilms versus traditional, hydrated-agar plates using samples collected from recirculated irrigation waters and cultures of isolated known species. The estimated count (in CFU mL) from a recirculated irrigation sample after 7 d of incubation on Petrifilm-YM was only 5.5% of the count quantified using sabouraud dextrose agar (SDA) with chloramphenicol after 14 d. In a separate experiment with a known species, Petrifilm-YM did not successfully culture zoospores of . Isolates of viable zoospores were cultured successfully on potato-dextrose agar (PDA), with comparable counts with a vegetable juice medium supplemented with the antibiotics pimaricin, ampicillin, rifamycin, pentochloronitrobenzene and hymexazol (PARP-H). The quantification of pv. Begoniaceae on Petrifilm-AC was not significantly different ( < 0.05) than on PDA, but was lower than on Reasoner and Goldrich agar (R2A) or with a hemocytometer. The current formulation of Petrifilm-YM is unlikely to be a useful monitoring method for plant pathogens in irrigation water because of the inability to successfully culture oomycetes. However, Petrifilm-AC was an effective method to quantify bacteria and can provide an easy-to-use on-farm tool to monitor biofilm risk and microbial density.

  12. Use of Dehydrated Agar to Estimate Microbial Water Quality for Horticulture Irrigation.

    PubMed

    Meador, Dustin P; Fisher, Paul R; Guy, Charles L; Harmon, Philip F; Peres, Natalia A; Teplitski, Max

    2016-07-01

    Petrifilms are dehydrated agar culture plates that have been used to quantify colony forming units (CFU) mL of either aerobic bacteria (Petrifilm-AC) or fungus (Petrifilm-YM), depending on substrate composition. Microbes in irrigation systems can indicate biofilm risk and potential clogging of irrigation emitters. The research objective was to compare counts on Petrifilms versus traditional, hydrated-agar plates using samples collected from recirculated irrigation waters and cultures of isolated known species. The estimated count (in CFU mL) from a recirculated irrigation sample after 7 d of incubation on Petrifilm-YM was only 5.5% of the count quantified using sabouraud dextrose agar (SDA) with chloramphenicol after 14 d. In a separate experiment with a known species, Petrifilm-YM did not successfully culture zoospores of . Isolates of viable zoospores were cultured successfully on potato-dextrose agar (PDA), with comparable counts with a vegetable juice medium supplemented with the antibiotics pimaricin, ampicillin, rifamycin, pentochloronitrobenzene and hymexazol (PARP-H). The quantification of pv. Begoniaceae on Petrifilm-AC was not significantly different ( < 0.05) than on PDA, but was lower than on Reasoner and Goldrich agar (R2A) or with a hemocytometer. The current formulation of Petrifilm-YM is unlikely to be a useful monitoring method for plant pathogens in irrigation water because of the inability to successfully culture oomycetes. However, Petrifilm-AC was an effective method to quantify bacteria and can provide an easy-to-use on-farm tool to monitor biofilm risk and microbial density. PMID:27380096

  13. Cost-effective nanoporous Agar-Agar polymer/Nickel powder composite particle for effective bio-products adsorption by expanded bed chromatography.

    PubMed

    Asgari, Setareh; Jahanshahi, Mohsen; Rahimpour, Ahmad

    2014-09-26

    In the present work a novel kind of dense nanoporous composite matrix for expanded bed application has been successfully first prepared with Nickel powder as a densifier and was covered with Agar-Agar layer as a skeleton, through the method of water-in-oil emulsification. Agar-Agar is a porous and inexpensive polymer. In order to fabricate cost-effective adsorbent with favorable qualities Agar-Agar polymer was used. Thereafter, the customized composite particle was modified by pseudo-affinity dye-ligand, Reactive Blue 4 (RB4), aimed at preparing a pseudo-affinity adsorbent (RB4-Agar-Ni) for bioprodut adsorption from aqueous solution. Bovine Serum Albumin (BSA) was selected as a model protein to investigate the adsorption behavior in batchwise and expanded bed chromatography, and the obtained results were evaluated with that of Streamline™ (Amersham-Pharmacia Biotech, Sweden). Spherical appearance and porous structure of composite particles were observed by the optical microscope (OM) and scanning electronic microscope (SEM). The results suggested that the matrices followed the logarithmic normal size distribution with the range of 65-300 μm and average diameter of 126.81-151.47 μm, proper wet density of 1.64-2.78 g/ml, water content of 62.74-34%, porosity of 98-90% and pore size of about 38-130 nm. For better comprehension of the impact of solid phase properties on the performance of the expanded bed, the expansion and hydrodynamic properties of a composite matrix with a series of densities was evaluated and estimated by the retention time distribution method (RTD) in an expanded bed and was compared with that of other matrices. According to obtained results the expansion factors under the same fluid velocity decreased by increasing the matrix density. Moreover, the axial dispersion coefficient (Dax) is the most appropriate parameter for evaluating the stability of expanded bed, on various operating conditions, such as different flow velocity, bed expansion

  14. Cost-effective nanoporous Agar-Agar polymer/Nickel powder composite particle for effective bio-products adsorption by expanded bed chromatography.

    PubMed

    Asgari, Setareh; Jahanshahi, Mohsen; Rahimpour, Ahmad

    2014-09-26

    In the present work a novel kind of dense nanoporous composite matrix for expanded bed application has been successfully first prepared with Nickel powder as a densifier and was covered with Agar-Agar layer as a skeleton, through the method of water-in-oil emulsification. Agar-Agar is a porous and inexpensive polymer. In order to fabricate cost-effective adsorbent with favorable qualities Agar-Agar polymer was used. Thereafter, the customized composite particle was modified by pseudo-affinity dye-ligand, Reactive Blue 4 (RB4), aimed at preparing a pseudo-affinity adsorbent (RB4-Agar-Ni) for bioprodut adsorption from aqueous solution. Bovine Serum Albumin (BSA) was selected as a model protein to investigate the adsorption behavior in batchwise and expanded bed chromatography, and the obtained results were evaluated with that of Streamline™ (Amersham-Pharmacia Biotech, Sweden). Spherical appearance and porous structure of composite particles were observed by the optical microscope (OM) and scanning electronic microscope (SEM). The results suggested that the matrices followed the logarithmic normal size distribution with the range of 65-300 μm and average diameter of 126.81-151.47 μm, proper wet density of 1.64-2.78 g/ml, water content of 62.74-34%, porosity of 98-90% and pore size of about 38-130 nm. For better comprehension of the impact of solid phase properties on the performance of the expanded bed, the expansion and hydrodynamic properties of a composite matrix with a series of densities was evaluated and estimated by the retention time distribution method (RTD) in an expanded bed and was compared with that of other matrices. According to obtained results the expansion factors under the same fluid velocity decreased by increasing the matrix density. Moreover, the axial dispersion coefficient (Dax) is the most appropriate parameter for evaluating the stability of expanded bed, on various operating conditions, such as different flow velocity, bed expansion

  15. Agar/collagen membrane as skin dressing for wounds.

    PubMed

    Bao, Lei; Yang, Wei; Mao, Xuan; Mou, Shansong; Tang, Shunqing

    2008-12-01

    Agar, a highly hydrophilic polymer, has a special gel property and favorable biocompatibility, but moderate intension strength in an aqueous condition and a low degradation rate. In order to tailor both properties of mechanical intension and degradation, type I collagen was composited with agar in a certain ratio by drying at 50 degrees C or by a freeze-dry process. Glutaraldehyde was chosen as a crosslinking agent, and the most favorable condition for crosslinking was that the weight ratio of agar to glutaraldehyde was 66.7 and the pH value about 5. Dynamic mechanical analysis results showed that the single agar membrane had a modulus value between 640 MPa and 1064 MPa, but it was between 340 MPa and 819 MPa after being composited with type I collagen. It was discovered under an optical microscope that the pores were interconnected in the composite scaffolds instead of the honeycomb-like pores in a single type I collagen scaffold or the laminated gaps in a single agar scaffold. The results of an acute toxicity test disclosed that the composites were not toxic to mice although the composites were crosslinked with a certain concentration of glutaraldehyde. The results of gross examinations showed that when the composite membranes or scaffolds were applied to a repair rabbit skin lesion, the composites had a good repair effect without infection, liquid exudation or visible scar in the lesion covered with them. But in the control group, the autologous skin showed necrosis and there were a lot of scar tissues in the lesion site. H&E staining results showed that the repair tissue was similar to the normal one and very few scaffolds or membranes were left without degradation after 2 or 3 weeks. In conclusion, it is proved that type I collagen increases the toughness of the agar membrane, and the agar/type I collagen composites are promising biomaterials as wound dressings for healing burns or ulcers.

  16. Production of microbial medium from defatted brebra (Milletia ferruginea) seed flour to substitute commercial peptone agar

    PubMed Central

    Andualem, Berhanu; Gessesse, Amare

    2013-01-01

    Objective To investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour. Methods 'Defatted process, inoculums preparation, evaluation of bacterial growth, preparation of cooked and hydrolyzed media and growth turbidity of tested bacteria were determined. Results Two percent defatted flour was found to be suitable concentration for the growth of pathogenic bacteria: Escherichia coli (ATCC 25922) (E. coli), Pseudomonas aeruginosa (ATCC 27853), Salmonella (NCTC 8385) and Shigella flexneri (ATCC 12022) (S. flexneri), while 3% defatted flour was suitable for Staphylococcus aureus (ATCC 25923) (S. aureus). E. coli (93±1) and S. flexneri (524±1) colony count were significantly (P≤0.05) greater in defatted flour without supplement than in supplemented medium. E. coli [(3.72×109±2) CFU/mL], S. aureus [(7.4×109±2) CFU/mL], S. flexneri [(4.03×109±2) CFU/mL] and Salmonella [(2.37×109±1) CFU/mL] in non-hydrolyzed sample were statistically (P≤0.05) greater than hydrolyzed one and commercial peptone agar. Colony count of Salmonella [(4.55×109±3) CFU/mL], S. flexneri [(5.40×109±3) CFU/mL] and Lyesria moncytogenes (ATCC 19116) [(5.4×109±3) CFU/mL] on raw defatted flour agar was significantly (P≤0.05) greater than cooked defatted flour and commercial peptone agar. Biomass of E. coli, S. aureus, Salmonella and Enterococcus faecalis in non-hydrolyzed defatted flour is highly increased over hydrolyzed defatted flour and commercial peptone broth. Conclusions The defatted flour agar was found to be better microbial media or comparable with peptone agar. The substances in it can serve as sources of carbon, nitrogen, vitamins and minerals that are essential to support the growth of microorganisms without any supplements. Currently, all supplements of peptone agar are very expensive in the market. PMID:24075344

  17. Evaluation of chromogenic agar, [corrected] VITEK2 YST and VITEK® MS for identification of Candida strains isolated from blood cultures.

    PubMed

    Sariguzel, Fatma Mutlu; Berk, Elife; Koc, Ayse Nedret; Sav, Hafize; Aydemir, Gonca

    2015-12-01

    The aim of this study is to compare conventional methods, chromogenic agar, [corrected] VITEK2 YST card and VITEK®MS system for the identification of Candida strains isolated from blood cultures. Fifty-four strains were identified according to conventional methods, chromogenic agar, [corrected] VITEK2 YST card and VITEK®MS. Sequencing was used as the reference method. The 54 strains included 32 Candida parapsilosis, 19 Candida albicans, 1 Candida glabrata and 2 Candida tropicalis according to the reference method. One C. albicans and one C. glabrata isolate were misidentified as C. parapsilosis by chromogenic agar. [corrected]. Two C. parapsilosis and three C. albicans isolates were misidentified by VITEK2 YST card. Chromogenic agar, [corrected] VITEK2 YST card and VITEK®MS identified correctly 96.2%, 90.7% and 100% of all strains, respectively. We found that the chromogenic agar, [corrected] VITEK2 YST card and VITEK®MS system are easy, rapid and accurate alternative methods for the identification of yeast species in the clinical microbiology laboratory.

  18. Blood agar and Mycobacterium tuberculosis: the end of a dogma.

    PubMed

    Drancourt, M; Carrieri, P; Gévaudan, M-J; Raoult, D

    2003-04-01

    Incidental blood agar-based recovery of Mycobacterium tuberculosis led us to further investigate this routine medium for primary isolation and culture of M. tuberculosis. Fifteen respiratory tract and eight lymph node Ziehl-Neelsen-positive specimens were inoculated in parallel into tubes containing egg-based medium and 5% sheep blood agar. Colonies appeared sooner on this medium than on the egg-based medium, but this difference was not significant (P = 0.11, analysis of variance [ANOVA] test). Further experiments compared the growth of 38 respiratory and lymph node M. tuberculosis isolates when subcultured on the two media. After 6 days of incubation, 21 of 38 isolates had grown on blood agar, and the mean number of colonies was significantly greater on blood agar than on the egg-based medium (P < 0 0.001, ANOVA test). These results demonstrate that M. tuberculosis grows easily on blood agar within 1to 2 weeks, indicating that this basic medium is suitable for laboratory diagnosis of tuberculosis in addition to other media. Laboratories that routinely use prolonged incubations of blood plates, for example, for the recovery of Bartonella species, should consider the potential safety implications of encountering this highly infectious pathogen.

  19. Photothermal characterization of the gelation process in Gelidium robustum Agar

    NASA Astrophysics Data System (ADS)

    Freile-Pelegrín, Y.; Bante, J.; Alvarado-Gil, J. J.; Yánez-Limón, J. M.

    2005-06-01

    Agar is a hydrophilic colloid formed by polysaccharides, whose ability to form reversible gels simply by cooling hot aqueous solutions is the most important property and can be regarded as the prototype and model for all gelling systems. In this paper the evolution of the gelation process of agar obtained from algae of the species Gelidium robustum, using the photopyroelectric technique is reported. It is shown that thermal effusivity increase when the agar is cooled, reaching a maximum value around 37°C. The increase in thermal effusivity can be related to the increasing of the bondings in the gel as temperature decreases, reaching the maximum at the gelation point. The decrease of the thermal effusivity at lower temperature could be due to the syneresis process involving a gradual release of water after gelation.

  20. Fly agaric (Amanita muscaria) poisoning, case report and review.

    PubMed

    Satora, Leszek; Pach, Dorota; Butryn, Beata; Hydzik, Piotr; Balicka-Slusarczyk, Barbara

    2005-06-01

    Gathering and eating mushrooms and other plants containing psychoactive substances has become increasingly popular among young people experimenting with drugs. Dried fly agaric Amanita muscaria fruiting bodies were eaten by five young persons (18-21 years of age) at a party in order to evoke hallucinations. Visual and auditory hallucinations occurred in four of them, whereas a 18-year-old girl lost consciousness. The following morning, she went to the Clinic of Toxicology. Due to the fact that not all the active substances present in the fly agaric have been identified, and some of them have an effect after a period of latency, the patient was admitted for several days of observation during which check-up examinations were performed. After four days without any problems, she was discharged. The poisoning regressed with no organ complications. The remaining persons who had eaten the fly agaric were free from any complaints. PMID:15904689

  1. Agar-Block Microcosms for Controlled Plant Tissue Decomposition by Aerobic Fungi

    PubMed Central

    Schilling, Jonathan S.

    2011-01-01

    The two principal methods for studying fungal biodegradation of lignocellulosic plant tissues were developed for wood preservative testing (soil-block; agar-block). It is well-accepted that soil-block microcosms yield higher decay rates, fewer moisture issues, lower variability among studies, and higher thresholds of preservative toxicity. Soil-block testing is thus the more utilized technique and has been standardized by American Society for Testing and Materials (ASTM) (method D 1413-07). The soil-block design has drawbacks, however, using locally-variable soil sources and in limiting the control of nutrients external (exogenous) to the decaying tissues. These drawbacks have emerged as a problem in applying this method to other, increasingly popular research aims. These modern aims include degrading lignocellulosics for bioenergy research, testing bioremediation of co-metabolized toxics, evaluating oxidative mechanisms, and tracking translocated elements along hyphal networks. Soil-blocks do not lend enough control in these applications. A refined agar-block approach is necessary. Here, we use the brown rot wood-degrading fungus Serpula lacrymans to degrade wood in agar-block microcosms, using deep Petri dishes with low-calcium agar. We test the role of exogenous gypsum on decay in a time-series, to demonstrate the utility and expected variability. Blocks from a single board rip (longitudinal cut) are conditioned, weighed, autoclaved, and introduced aseptically atop plastic mesh. Fungal inoculations are at each block face, with exogenous gypsum added at interfaces. Harvests are aseptic until the final destructive harvest. These microcosms are designed to avoid block contact with agar or Petri dish walls. Condensation is minimized during plate pours and during incubation. Finally, inoculum/gypsum/wood spacing is minimized but without allowing contact. These less technical aspects of agar-block design are also the most common causes of failure and the key source of

  2. Growth of Desulfovibrio on the Surface of Agar Media

    PubMed Central

    Iverson, Warren P.

    1966-01-01

    Growth of Desulfovibrio desulfuricans (API strain) was found to take place in an atmosphere of hydrogen on the agar surface of complex media, including yeast extract (Difco), and Trypticase Soy Agar (BBL) without any added reducing agents. For growth on a 2% yeast extract-agar surface in the absence of hydrogen (nitrogen atmosphere), sodium lactate was required in the medium. Growth on the surface of Trypticase Soy Agar (TSA) under nitrogen took place readily in the absence of an added hydrogen donor. A medium (TSA plus salts) is described based upon the addition of sodium lactate (4 ml per liter), magnesium sulfate (2 g per liter), and ferrous ammonium sulfate (0.05%) to TSA, which appears suitable for the isolation and growth of Desulfovibrio on the surface of agar plates in an atmosphere of hydrogen. Sodium lactate does not appear to be essential in this medium for good growth and sulfate reduction in a hydrogen atmosphere, but is essential in a nitrogen atmosphere. Growth of Desulfovibrio (hydrogen atmosphere) on the agar surface of media commonly used for its cultivation as well as on an inorganic medium containing bicarbonate as a source of carbon is poor and erratic unless inoculated (Desulfovibrio) plates of TSA plus salts are incubated in the same container with plates of these media. This stimulatory effect of incubation with inoculated plates of TSA plus salts medium appears to be due to as yet unidentified volatile material produced by D. desulfuricans when growing on this medium. Another volatile material, or possibly the identical material, appears to act similarly to a hydrogen donor. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:5955798

  3. Is blood agar an alternative to sabouraud dextrose agar for the isolation of fungi in patients with mycotic keratitis.

    PubMed

    Reddy, Ashok Kumar; Brahmaiah, Upputuri; Narayen, Nitesh; Reddy, Ravi Kumar; Reddy, Rupak Kumar; Chitta, Meghraj; Prasad, Srinivas; Swarup, Rishi; Mohiuddin, Syed Maaz; Reddy, Madhukar; Aasuri, Murali K; Murthy, B S R; Bhide, Milind; Ahmed, Sajid

    2013-06-01

    To compare the blood agar (BA), sabouraud dextrose agar (SDA) and chocolate agar (CA) for the isolation of fungi in patients with mycotic keratitis. Corneal Scrapings of 229 patients with clinically diagnosed microbial keratitis were inoculated on BA, SDA, CA. The culture media were evaluated for the rate and time taken for the fungal growth. Seventy six of 229 patients had fungal keratitis. Fungus grew on BA in 60/76(78.9 %), on SDA in 76/76 (100 %), on CA in 40/76(52.6 %) patients. The fungi which grew on BA (60/76) also grown on SDA at the same time. The colony morphologies of different fungi were better on SDA than BA/CA. Among the different culture media, SDA is essential for the isolation fungi in patients with mycotic keratitis.

  4. Proportional Reasoning with a Pyramid

    ERIC Educational Resources Information Center

    Mamolo, Ami; Sinclair, Margaret; Whiteley, Walter J.

    2011-01-01

    Proportional reasoning pops up in math class in a variety of places, such as while making scaled drawings; finding equivalent fractions; converting units of measurement; comparing speeds, prices, and rates; and comparing lengths, areas, and volume. Students need to be exposed to a variety of representations to develop a sound understanding of this…

  5. Proportional Hazards Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Reed-Rhoads, Teri; Barker, Kash

    2008-01-01

    Survival analysis is a statistical tool used to describe the duration between events. Many processes in medical research, engineering, and economics can be described using survival analysis techniques. This research involves studying engineering college student graduation using Cox proportional hazards models. Among male students with American…

  6. Social Justice and Proportional Reasoning

    ERIC Educational Resources Information Center

    Simic-Muller, Ksenija

    2015-01-01

    Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…

  7. Saving Money Using Proportional Reasoning

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.; Garney, Sandra

    2016-01-01

    It is beneficial for students to discover intuitive strategies, as opposed to the teacher presenting strategies to them. Certain proportional reasoning tasks are more likely to elicit intuitive strategies than other tasks. The strategies that students are apt to use when approaching a task, as well as the likelihood of a student's success or…

  8. Susceptibility of a polycaprolactone-based root canal filling material to degradation using an agar-well diffusion assay

    PubMed Central

    Hiraishi, Noriko; Sadek, Fernanda T.; King, Nigel M.; Ferrari, Marco; Pashley, David H.; Tay, Franklin R

    2013-01-01

    Purpose Cholesterol esterase is both a component of salivary hydrolases as well as an inflammatory cell-derived enzyme and has been shown to cause biodegradation of methacrylate-based resin composites. This study examined whether Resilon, a polycaprolactone-based thermoplastic root filling material is susceptible to biodegradation by cholesterol esterase using agar-well diffusion assay of serially-diluted aqueous Resilon emulsions that were dispersed in agar. Materials and methods Emulsions of Resilon and polycaprolactone were prepared and dispersed in agar on culture plates. Two different concentrations of a cholesterol esterase (0.3 and 1.2 U/mL) were prepared and fed to wells prepared in the agar plates using an agar-well diffusion assay for examination the degradation of polymeric materials. Results Degradation of the emulsified Resilon was manifested as the formation of clear zones of different sizes around the agar wells. No clear zones were observed in agar wells that contain sterile distilled water as the negative control. Clinical significance Although dispersion Resilon into an emulsion is not the way in which this material is employed as a root filling material, the potential for Resilon to be degraded by cholesterol esterase is of potential concern as one cannot limit the degradation of extruded Resilon from a root apex by monocyte-derived macrophages to just the anatomical root apex. As the present study employed a high concentration of cholesterol esterase, further studies should be directed to examining the degradation of Resilon using macrophage cell cultures. PMID:18578181

  9. Progress in studying scintillator proportionality: Phenomenological model

    SciTech Connect

    Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

    2009-04-30

    We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.

  10. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  11. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  12. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  13. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  14. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  15. Improving agar electrospinnability with choline-based deep eutectic solvents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One percent agar (% wt) was dissolved in the deep eutectic solvent (DES), (2-hydroxyethyl) trimethylammonium chloride/urea at a 1:2 molar ratio, and successfully electrospun into nanofibers. An existing electrospinning set-up, operated at 50 deg C, was adapted for use with an ethanol bath to collect...

  16. Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion–reaction based continuum model

    NASA Astrophysics Data System (ADS)

    Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

    2016-08-01

    Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion–reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm’s shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here.

  17. Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion-reaction based continuum model.

    PubMed

    Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

    2016-01-01

    Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion-reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm's shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here. PMID:27434099

  18. Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion-reaction based continuum model

    NASA Astrophysics Data System (ADS)

    Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

    2016-08-01

    Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion-reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm’s shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here.

  19. What is proportional reasoning, anyway?

    NASA Astrophysics Data System (ADS)

    Subero, Keron; Kanim, Stephen

    2007-10-01

    There appears to be a correlation between some measures of scientific reasoning skills and gain on conceptual measures of student understanding of introductory physics such as the Force Concept Inventory. At NMSU, we have established a correlation between pretest scores on proportional reasoning tasks and student performance on conceptual post-tests in the introductory lab. Proponents of a Piagetian model of cognitive development would call these scientific reasoning skills `operational capacities'' that signal the last transition in human intellectual growth from ``Concrete Operational'' to ``Formal'' reasoning. Seen in this light, the correlations described above suggest a cognitive ``deficit'' associated with development. We are exploring the possibility that proportional reasoning may in fact be a blanket term to describe many smaller elements of skills which students often seem to lack. In this talk, I will present some initial results from our investigation.

  20. Infrared thermography analysis of thermal diffusion induced by RF magnetic field on agar phantoms loaded with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bante-Guerra, Jose; Macías, J. D.; Caballero-Aguilar, L.; Vales-Pinzón, C.; Alvarado-Gil, J. J.

    2013-02-01

    Recently, several treatments for fighting malignant tumors have been designed. However these procedures have well known inconveniences, depending on their applicability, tumor size and side effects, among others. Magnetic hyperthermia is a safe, non-invasive method for cancer therapy. This treatment is applied via elevation of target tissue temperature by dissipation of heat from Magnetic Nanoparticles (MNPs), previously located within the tumor. The induction of heat causes cell death and therefore the removal of the tumor. In this work the thermal diffusion in phantoms of agar loaded with magnetic nanoparticles (MNPs) is studied using the infrared thermography technique, which is widely used in biology/medicine (e.g. skin temperature mapping). Agar is one of the materials used to simulate different types of body tissues, these samples are known as "phantoms". Agar is of natural origin, low cost and high degree of biocompatibility. In this work the agar gel was embedded with MNPs by coprecipitation and placed in an alternating magnetic field radiation. As a consequence, the energy from the radiation source is dissipated as heat and then transferred from the MNP to the gel, increasing its temperature. For the temperature analysis, the samples of agar gel were stimulated by RF magnetic field generated by coils. Heating was measured with infrared thermography using a Thermovision A20M infrared camera. Thermographic images allowed obtaining the dependence of thermal diffusion in the phantom as a function of the magnitude of the applied RF magnetic field and the load of magnetic particles.

  1. Agar-agar entrapment increases the stability of endo-β-1,4-xylanase for repeated biodegradation of xylan.

    PubMed

    Bibi, Zainab; Shahid, Faiza; Ul Qader, Shah Ali; Aman, Afsheen

    2015-04-01

    Microbial xylanases, specially endo-β-1,4-xylanase catalyzes the hydrolysis of xylan, is considered one of the most significant hydrolases. It has numerous applications but most extensively is utilized in paper and pulp industry as a bio-bleaching agent. Immobilization technique is comprehensively studied with the expectation of modifying and improving enzyme stability and characteristics for commercial purposes. Currently, matrix entrapment technique is applied to immobilize endo-β-1,4-xylanase within agar-agar gel beads produced by Geobacillus stearothermophilus KIBGE-IB29. Maximal enzyme immobilization yield was achieved at 2.5% of agar-agar concentration. Optimized conditions demonstrated an increase in the optimal reaction time from 05 min to 30 min and incubation temperature from 50 °C to 60 °C with reference to free enzyme whereas; no effect was observed for optimum pH. Entrapment technique uniquely changed the kinetic parameters of immobilized endo-β-1,4-xylanase (Km: 0.5074 mg min(-1) to 0.5230 mg min(-1) and Vmax: 4773 U min(-1) to 968 U min(-1)) as compared to free enzyme. However, immobilized enzyme displayed broad thermal stability and retained 79.0% of its initial activity at 80 °C up to 30 min whereas; free enzyme completely lost its activity at this temperature. With respect to economic feasibility, the immobilized enzyme showed impressive recycling efficiency up to six reaction cycles. PMID:25603143

  2. Thermal-induced ageing of agar solutions: impact on the structural and mechanical properties of agar gels

    NASA Astrophysics Data System (ADS)

    Mao, Bosi; Bentaleb, Ahmed; Louerat, Frédéric; Divoux, Thibaut; Snabre, Patrick

    Numerous hydrogels are prepared by cooling down to ambient temperature, aqueous polymer solutions brought to a boil. Although the incubation time of the polymer solution at such a high temperature could be used as a tuning parameter, its impact on the subsequent gelation has been poorly investigated. Here we study the effect of prolonged heating at 80°C on a 1.5% wt solution of agar, a natural polysaccharide. The incubation time is varied from a few hours up to five days. We show that the agar sol. continuously degrades as the result of both the hydrolysis and the intermolecular oxidation of the polymer chains. Furthermore, electronic microscopy and X-ray diffraction experiments reveal that gels formed from older agar sols display an increasingly coarser microstructure composed of micron-sized aggregated pieces of polysaccharides, in contrast with the fibrous-like structure of gels made from fresh sols. Along with structural changes prolonged incubation time leads to weaker gels of lower shear elastic modulus. Finally, macro-indentation experiments coupled to direct visualization show that increasing the incubation time of the agar sol. decreases the yield strain of the gel by a factor of three, while the rupture scenario turns continuously from brittle to ductile-like. Acknowledging funding from BioMérieux & CNRS.

  3. Qualitative and quantitative agar invasion test based on bacterial colony/biofilm.

    PubMed

    Corcuera, María Teresa; Gómez-Aguado, Fernando; Gómez-Lus, María Luisa; Ramos, Carmen; de la Parte, María Antonia; Alonso, María José; Prieto, José

    2013-09-01

    Invasion of the culture medium is a feature frequently studied in yeasts, in which it has been related to a greater virulence, but it is practically unknown in bacteria. Recently, it has been demonstrated that several clinically relevant bacterial species were also able of invading agar media, so it was necessary to design a microbiological assay to study the expression of this character in bacteria. Accordingly, a bacterial agar invasion test based on colony/biofilm development was designed, which allows qualitative and quantitative characterization of bacterial growth into the agar culture medium. Once the culture conditions were optimized, the test was applied to 90 strains from nine bacterial species, validating its usefulness for differentiating invasive strains (positive) from those non invasive (negative). The test also allows sorting invasive strains according to agar invasion intensity (low, moderate, high) and topographic invasion pattern (peripheral, homogeneous, mixed). Moreover, an image analysis routine to quantify the invasion was developed. Implemented method enables direct measuring of two invasion parameters (invasion area and number of invasion dots), automated calculation of three relative variables (invasion relative area, invasion dots relative density, and invasion dot average area), and the establishment of strain specific frequency histograms. This new methodology is simple, fast, reproducible, objective, inexpensive and can be used to study a great number of specimens simultaneously, all of which make it suitable for incorporation to the routine of any microbiology laboratory. It could also be a useful tool for additional studies related to clinical aspects of bacterial isolates such as virulence and antimicrobial response.

  4. Evaluation of three decarboxylating agar media to detect histamine and tyramine-producing bacteria in ripened sausages.

    PubMed

    Roig-Sagués, A X; Hernàndez-Herrero, M M; López-Sabater, E I; Rodríguez-Jerez, J J; Mora-Ventura, M T

    1997-11-01

    Histidine- and tyrosine-decarboxylase activity of 175 strains of bacteria isolated from eight retail samples of Spanish ripened sausages was tested in three decarboxylating agars (Niven medium, Joosten and Northolt medium and modified decarboxylating agar of Maijala) and confirmed by an enzymic method (histamine) and thin-layer chromatography (tyramine). Enterobacteria and pseudomonads showed the highest percentage of positive responses to histamine and tyramine in the three decarboxylating agars, but only enterobacteria were subsequently confirmed as histamine-producing. Confirmed tyramine-producing strains were all identified as enterococci or lactic acid bacteria. The medium described by Joosten and Northolt was more sensitive and faster at detecting tyramine-producing microorganisms. However, all three media failed to detect one histamine-positive strain of lactic acid bacteria used as a control.

  5. How do microorganisms influence trace element uptake by plants? Screening in an agar model rhizosphere.

    NASA Astrophysics Data System (ADS)

    Marchetti, M.; Robinson, B. H.; Evangelou, M. W. H.; Vachey, A.; Schwitzguebel, J. P.; Bernier-Latmani, R.; Schulin, R.

    2009-04-01

    Trace elements (TE) are essential for humans and plants, but they may be toxic if their concentration is too high. For this reason, the management of TE in soils is very important. In some cases it may be necessary to increase the uptake of nutrients or TE by plants, for example in a biofortification perspective. Conversely, in some other cases TE uptake by plants should be decreased, for instance to avoid heavy metals entering the food chain via edible crops. Microorganisms living in the rhizosphere affect trace element (TE) uptake by plants. However, due to the complexity of this space and the variety of microorganisms that occur there, it is difficult to isolate the effect of any particular strain. To overcome this hurdle, we developed a system in which we grew plants under sterile conditions in agar and inoculated their rhizosphere with a single, well-defined microbial strain. For many years, agar has been used as a growth substrate for microorganisms and plant tissues. It is cheap, easy to use, and can be autoclaved to ensure its sterility. Because of its widespread use, an experiment conducted using this substrate can be reproduced under the same conditions in any laboratory. In contrast to soil, there is little interaction between the trace elements and the agar matrix. There are many studies investigating the influence of microorganisms on TE uptake by plants. However, so far only a small variety of microorganisms has been tested on few plant species. Therefore, the first objective of our research was to develop a method to rapidly screen a large variety of microorganisms on various plant species. Once this goal was achieved, we sought to study the effect of single, well-defined microbial strains on TE uptake by sunflower and wheat. The substrate for plants growth was a 10% agar solution prepared with modified Hoagland's solution and a TE solution containing 1 mg/kg Pb and molar equivalents of Cu, Ni and Zn. The agar solution was autoclaved and poured into

  6. Photodetectors for Scintillator Proportionality Measurement

    SciTech Connect

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  7. Campylobacter in broiler slaughter samples assessed by direct count on mCCDA and Campy-Cefex agar.

    PubMed

    Gonsalves, Camila Cristina; Borsoi, Anderlise; Perdoncini, Gustavo; Rodrigues, Laura Beatriz; do Nascimento, Vladimir Pinheiro

    2016-01-01

    Campylobacter spp. cause foodborne illnesses in humans primarily through the consumption of contaminated chicken. The aim of this study was to evaluate the United States Department of Agriculture's (USDA) recommended methodology, protocol MLG 41.02, for the isolation, identification and direct plate counting of Campylobacter jejuni and C. coli samples from the broiler slaughtering process. A plating method using both mCCDA and Campy-Cefex agars is recommended to recover Campylobacter cells. It is also possible to use this method in different matrices (cloacal swabs and water samples). Cloacal swabs, samples from pre-chiller and post-chiller carcasses and samples of pre-chiller, chiller and direct supply water were collected each week for four weeks from the same flock at a slaughterhouse located in an abattoir in southern Brazil. Samples were analyzed to directly count Campylobacter spp., and the results showed a high frequency of Campylobacter spp. on Campy-Cefex agar. For the isolated species, 72% were identified as Campylobacter jejuni and 38% as Campylobacter coli. It was possible to count Campylobacter jejuni and Campylobacter coli from different samples, including the water supply samples, using the two-agar method. These results suggest that slaughterhouses can use direct counting methods with both agars and different matrices as a monitoring tool to assess the presence of Campylobacter bacteria in their products. PMID:27237112

  8. Mupirocin-mucin agar for selective enumeration of Bifidobacterium bifidum.

    PubMed

    Pechar, Radko; Rada, Vojtech; Parafati, Lucia; Musilova, Sarka; Bunesova, Vera; Vlkova, Eva; Killer, Jiri; Mrazek, Jakub; Kmet, Vladimir; Svejstil, Roman

    2014-11-17

    Bifidobacterium bifidum is a bacterial species exclusively found in the human intestinal tract. This species is becoming increasingly popular as a probiotic organism added to lyophilized products. In this study, porcine mucin was used as the sole carbon source for the selective enumeration of B. bifidum in probiotic food additives. Thirty-six bifidobacterial strains were cultivated in broth with mucin. Only 13 strains of B. bifidum utilized the mucin to produce acids. B. bifidum was selectively enumerated in eight probiotic food supplements using agar (MM agar) containing mupirocin (100 mg/L) and mucin (20 g/L) as the sole carbon source. MM agar was fully selective if the B. bifidum species was presented together with Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium longum subsp. longum species and with lactic acid bacteria (lactobacilli, streptococci). Isolated strains of B. bifidum were identified using biochemical, PCR, MALDI-TOF procedures and 16S rRNA gene sequencing. The novel selective medium was also suitable for the isolation of B. bifidum strains from human fecal samples.

  9. Modeling development of inhibition zones in an agar diffusion bioassay

    PubMed Central

    Chandrasekar, Vaishnavi; Knabel, Stephen J; Anantheswaran, Ramaswamy C

    2015-01-01

    A two-temperature agar diffusion bioassay is commonly used to quantify the concentration of nisin using Micrococcus luteus as the indicator microorganism. A finite element computational model based on Fick's second law of diffusion was used to predict the radius of the inhibition zone in this diffusion bioassay. The model developed was used to calculate nisin concentration profiles as a function of time and position within the agar. The minimum inhibitory concentration (MIC) of nisin against M. luteus was determined experimentally. The critical time (Tc) for growth of M. luteus within the agar diffusion bioassay was experimentally determined using incubation studies with nisin. The radius of the inhibition zone was predicted from the computational model as the location where the predicted nisin concentration at Tc was equal to MIC. The MIC was experimentally determined to be 0.156 μg mL−1, and Tc was determined to be 7 h. Good agreement (R2 = 0.984) was obtained between model-predicted and experimentally determined inhibition zone radii. PMID:26405525

  10. Mupirocin-mucin agar for selective enumeration of Bifidobacterium bifidum.

    PubMed

    Pechar, Radko; Rada, Vojtech; Parafati, Lucia; Musilova, Sarka; Bunesova, Vera; Vlkova, Eva; Killer, Jiri; Mrazek, Jakub; Kmet, Vladimir; Svejstil, Roman

    2014-11-17

    Bifidobacterium bifidum is a bacterial species exclusively found in the human intestinal tract. This species is becoming increasingly popular as a probiotic organism added to lyophilized products. In this study, porcine mucin was used as the sole carbon source for the selective enumeration of B. bifidum in probiotic food additives. Thirty-six bifidobacterial strains were cultivated in broth with mucin. Only 13 strains of B. bifidum utilized the mucin to produce acids. B. bifidum was selectively enumerated in eight probiotic food supplements using agar (MM agar) containing mupirocin (100 mg/L) and mucin (20 g/L) as the sole carbon source. MM agar was fully selective if the B. bifidum species was presented together with Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium longum subsp. longum species and with lactic acid bacteria (lactobacilli, streptococci). Isolated strains of B. bifidum were identified using biochemical, PCR, MALDI-TOF procedures and 16S rRNA gene sequencing. The novel selective medium was also suitable for the isolation of B. bifidum strains from human fecal samples. PMID:25217723

  11. Modeling development of inhibition zones in an agar diffusion bioassay.

    PubMed

    Chandrasekar, Vaishnavi; Knabel, Stephen J; Anantheswaran, Ramaswamy C

    2015-09-01

    A two-temperature agar diffusion bioassay is commonly used to quantify the concentration of nisin using Micrococcus luteus as the indicator microorganism. A finite element computational model based on Fick's second law of diffusion was used to predict the radius of the inhibition zone in this diffusion bioassay. The model developed was used to calculate nisin concentration profiles as a function of time and position within the agar. The minimum inhibitory concentration (MIC) of nisin against M. luteus was determined experimentally. The critical time (T c) for growth of M. luteus within the agar diffusion bioassay was experimentally determined using incubation studies with nisin. The radius of the inhibition zone was predicted from the computational model as the location where the predicted nisin concentration at T c was equal to MIC. The MIC was experimentally determined to be 0.156 μg mL(-1), and T c was determined to be 7 h. Good agreement (R (2) = 0.984) was obtained between model-predicted and experimentally determined inhibition zone radii.

  12. Evaluation of facial divine proportion in North Indian Population

    PubMed Central

    Khan, Naseem Ahmad; Nagar, Amit; Tandon, Pradeep; Singh, Gulshan Kumar; Singh, Alka

    2016-01-01

    Objective: To evaluate the facial divine proportion and its relationship with facial attractiveness in North Indian population. Materials and Methods: For evaluation of various facial proportions, standardized frontal facial photographs of total 300 subjects between 18 and 30 years of age were obtained. Black and white copies of these photographs were presented in front of an evaluation jury for assigning scores of facial attractiveness and finally 130 attractive subjects were selected. These subjects were divided into two groups, Group I (attractive females n = 65) and Group II (attractive males n = 65) and they were further analyzed for various parameters of facial proportions. Unpaired Student's t-test was used to compare both groups. Results: Group I showed that five of seven vertical facial proportions were close to divine proportion (1.618) whereas only two vertical proportions in Group II were close to it. Transverse facial proportions in both groups deviated more from divine proportion (1.618) and were closer to silver proportion (1.414). Conclusions: Most of the facial proportions of attractive females in the North-Indian population were close to the divine proportion. Thus, facial divine proportion could be an important factor in the perception of facial attractiveness of North-Indian attractive females.

  13. Evaluation of facial divine proportion in North Indian Population

    PubMed Central

    Khan, Naseem Ahmad; Nagar, Amit; Tandon, Pradeep; Singh, Gulshan Kumar; Singh, Alka

    2016-01-01

    Objective: To evaluate the facial divine proportion and its relationship with facial attractiveness in North Indian population. Materials and Methods: For evaluation of various facial proportions, standardized frontal facial photographs of total 300 subjects between 18 and 30 years of age were obtained. Black and white copies of these photographs were presented in front of an evaluation jury for assigning scores of facial attractiveness and finally 130 attractive subjects were selected. These subjects were divided into two groups, Group I (attractive females n = 65) and Group II (attractive males n = 65) and they were further analyzed for various parameters of facial proportions. Unpaired Student's t-test was used to compare both groups. Results: Group I showed that five of seven vertical facial proportions were close to divine proportion (1.618) whereas only two vertical proportions in Group II were close to it. Transverse facial proportions in both groups deviated more from divine proportion (1.618) and were closer to silver proportion (1.414). Conclusions: Most of the facial proportions of attractive females in the North-Indian population were close to the divine proportion. Thus, facial divine proportion could be an important factor in the perception of facial attractiveness of North-Indian attractive females. PMID:27630502

  14. Impaction onto a Glass Slide or Agar versus Impingement into a Liquid for the Collection and Recovery of Airborne Microorganisms

    PubMed Central

    Juozaitis, Arvydas; Willeke, Klaus; Grinshpun, Sergey A.; Donnelly, Jean

    1994-01-01

    To study impaction versus impingement for the collection and recovery of viable airborne microorganisms, three new bioaerosol samplers have been designed and built. They differ from each other by the medium onto which the bioaerosol particles are collected (glass, agar, and liquid) but have the same inlet and collection geometries and the same sampling flow rate. The bioaerosol concentrations recorded by three different collection techniques have been compared with each other: impaction onto a glass slide, impaction onto an agar medium, and impingement into a liquid. It was found that the particle collection efficiency of agar slide impaction depends on the concentration of agar in the collection medium and on the sampling time, when samples are collected on a nonmoving agar slide. Impingement into a liquid showed anomalous behavior with respect to the sampling flow rate. Optimal sampling conditions in which all three new samplers exhibit the same overall sampling efficiency for nonbiological particles have been established. Inlet and collection efficiencies of about 100% have been achieved for all three devices at a sampling flow rate of 10 liters/min. The new agar slide impactor and the new impinger were then used to study the biological factors affecting the overall sampling efficiency. Laboratory experiments on the total recovery of a typical environmental microorganism, Pseudomonas fluorescens ATCC 13525, showed that both sampling methods, impaction and impingement, provided essentially the same total recovery when relatively nonstressed microorganisms were sampled under optimal sampling conditions. Comparison tests of the newly developed bioaerosol samplers with those commercially available showed that the incorporation of our research findings into the design of the new samplers yields better performance data than data from currently available samplers. PMID:16349217

  15. Differential recovery of Streptococcus mutans from various mitis-salivarius agar preparations.

    PubMed Central

    Liljemark, W F; Okrent, D H; Bloomquist, C G

    1976-01-01

    Recoveries of Streptococcus mutans from human dental plaque were lower when plated on mitis-salivarius agar obtained from Baltimore Biological Laboratories as compared with mitis-salivarius agar obtained from Difco Laboratories. However, no difference in recoveries of established laboratory strains of S. mutans was observed between these two agar preparations. PMID:956358

  16. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, we report the successful fabrication of agar-based nanofibers by an electrospinning technique using water as the solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operated at 50 deg C, to avoid agar gelation. Pure agar solution 1% (w/w) showed inadequ...

  17. [Evaluation of the ChromID ESBL agar for the detection of ESBL-positive Enterobacteriaceae and vancomycin-resistant enterococcus isolates from urine cultures].

    PubMed

    Alışkan, Hikmet Eda; Colakoğlu, Sule; Turunç, Tuba; Demiroğlu, Yusuf Ziya

    2012-01-01

    Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae strains are frequent causative agents both in community-acquired infections and in nosocomial infections. The newly developed ChromID ESBL agar (bioMerieux, Marcy I'Etoile, France) is a chromogenic medium that helps rapid identification of ESBL-positive Enterobacteriaceae species from the clinical samples. The aim of this study was to evaluate the performance of ChromID ESBL agar in the rapid identification of ESBL-positive pathogens from the urine samples of the patients with urinary tract infections. A total of 672 urine samples (437 outpatients, 235 inpatients) were included in the study. All of the samples were inoculated simultaneously to 5% sheep blood agar, McConkey agar and ChromID ESBL agar media, and evaluated after incubation at 37°C for 18-24 hours. Gram-negative pathogens were tested for ESBL both by the standard combined double-disk diffusion (CDD) method using ceftazidime and cefotaxime disks and by doubledisk synergy (DDS) test. Among 672 urine cultures, 199 yielded microbial growth in routine media (sheep blood agar and/or McConkey agar), whereas 57 yielded bacterial growth in ChromID ESBL agar. When CDD method was accepted as the reference method according to Clinical and Laboratory Standards Institute (CLSI) recommendations, the sensitivity, specificity, positive and negative predictive values for ChromID ESBL agar for the detection of ESBL-positive bacteria in urinary tract infections were estimated as 97%, 92.9%, 89.1%, and 98.1%, respectively. Additionally, we also discovered that Chrom ID ESBL agar could detect vancomycin-resistant enterococci (VRE) as well as ESBL-positive bacteria, in our study. In order to investigate this observation we inoculated a total of 203 stock strains of Enterococcus spp. (118 vancomycin-sensitive, 85 vancomycin-resistant) to this medium. None of the vancomycinsensitive Enterococcus spp. did grow in ChromID ESBL medium, while 83 of the 85

  18. Multi-chamber electroosmosis using textile reinforced agar membranes--A promising concept for the future of hemodialysis.

    PubMed

    Kofler, Markus; Lenninger, Margit; Mayer, Gert; Neuwirt, Hannes; Grimm, Michael; Bechtold, Thomas

    2016-01-20

    Renal replacement therapy options are limited to hemodialysis and peritoneal dialysis (70% of US patients) or renal transplantation. Diffusion processes are the main physico-chemical principle behind hemodialysis. An alternative way to achieve liquid flow through membranes bases on the electroosmotic flow which is observed as electrokinetic phenomenon in porous membranes which bear surface charges. Agar consists of the non-ionic agarose and the negatively charged agaropectine thus an electroosmotic flux is observed in analytical electrophoresis. In this study the potential electroosmosis on textile reinforced agar membranes as separation method was investigated. Using a five-chamber electrolysis cell and an agar membrane/cellulose fabric composite an intensive electroosmotic flow of 1-2 ml cm(2) h(-1) at 100 mA cell current could be observed. The movement of cations in the negatively charged agar structure led to an intensive electroosmotic flux, which also transported uncharged molecules such as urea, glucose through the membrane. Separation of uncharged low molecular weight molecules is determined by the membrane characteristic. The transport of ions (K(+), PO4(3-), creatinine) and uncharged molecules (urea, glucose) in electroosmotic separation experiments was monitored using a pH 5.5 phosphate electrolyte with the aim to assess the overall transport processes in the electrochemical cell. The results demonstrate the potential of the method for filtration of biological fluids in the absence of external pressure or high shear rates.

  19. Cell-on-hydrogel platform made of agar and alginate for rapid, low-cost, multidimensional test of antimicrobial susceptibility.

    PubMed

    Sun, Han; Liu, Zhengzhi; Hu, Chong; Ren, Kangning

    2016-08-01

    Antimicrobial resistance (AMR) is a rapidly increasing threat to the effective treatment of infectious diseases worldwide. The two major remedies include: (1) using narrow-spectrum antibiotics based on rapid diagnosis; and (2) developing new antibiotics. A key part of both remedies is the antimicrobial susceptibility test (AST). However, the current standard ASTs that monitor colony formation are costly and time-consuming and the new strategies proposed are not yet practical to be implemented. Herein, we report a strategy to fabricate whole-hydrogel microfluidic chips using alginate-doped agar. This agar-based microfabrication makes it possible to prepare inexpensive hydrogel devices, and allows a seamless link between microfluidics and conventional agar-based cell culture. Different from common microfluidic systems, in our system the cells are cultured on top of the device, similar to normal agar plate culture; on the other hand, the microfluidic channels inside the hydrogel allow precise generation of linear gradient of drugs, thus giving a better performance than the conventional disk diffusion method. Cells in this system are not exposed to any shear flow, which allows the reliable tracking of individual cells and AST results to be obtained within 2-3 hours. Furthermore, our system could test the synergistic effect of drugs through two-dimensional gradient generation. Finally, the platform could be directly implemented to new drug discovery and other applications wherein a fast, cost-efficient method for studying the response of microorganisms upon drug administration is desirable. PMID:27452345

  20. Multi-chamber electroosmosis using textile reinforced agar membranes--A promising concept for the future of hemodialysis.

    PubMed

    Kofler, Markus; Lenninger, Margit; Mayer, Gert; Neuwirt, Hannes; Grimm, Michael; Bechtold, Thomas

    2016-01-20

    Renal replacement therapy options are limited to hemodialysis and peritoneal dialysis (70% of US patients) or renal transplantation. Diffusion processes are the main physico-chemical principle behind hemodialysis. An alternative way to achieve liquid flow through membranes bases on the electroosmotic flow which is observed as electrokinetic phenomenon in porous membranes which bear surface charges. Agar consists of the non-ionic agarose and the negatively charged agaropectine thus an electroosmotic flux is observed in analytical electrophoresis. In this study the potential electroosmosis on textile reinforced agar membranes as separation method was investigated. Using a five-chamber electrolysis cell and an agar membrane/cellulose fabric composite an intensive electroosmotic flow of 1-2 ml cm(2) h(-1) at 100 mA cell current could be observed. The movement of cations in the negatively charged agar structure led to an intensive electroosmotic flux, which also transported uncharged molecules such as urea, glucose through the membrane. Separation of uncharged low molecular weight molecules is determined by the membrane characteristic. The transport of ions (K(+), PO4(3-), creatinine) and uncharged molecules (urea, glucose) in electroosmotic separation experiments was monitored using a pH 5.5 phosphate electrolyte with the aim to assess the overall transport processes in the electrochemical cell. The results demonstrate the potential of the method for filtration of biological fluids in the absence of external pressure or high shear rates. PMID:26572331

  1. Challenging the principle of proportionality.

    PubMed

    Andersson, Anna-Karin Margareta

    2016-04-01

    The first objective of this article is to examine one aspect of the principle of proportionality (PP) as advanced by Alan Gewirth in his 1978 bookReason and Morality Gewirth claims that being capable of exercising agency to some minimal degree is a property that justifies having at least prima facie rights not to get killed. However, according to the PP, before the being possesses the capacity for exercising agency to that minimal degree, the extent of her rights depends on to what extent she approaches possession of agential capacities. One interpretation of PP holds that variations in degree of possession of the physical constitution necessary to exercise agency are morally relevant. The other interpretation holds that only variations in degree of actual mental capacity are morally relevant. The first of these interpretations is vastly more problematic than the other. The second objective is to argue that according to the most plausible interpretation of the PP, the fetus' level of development before at least the 20th week of pregnancy does not affect the fetus' moral rights status. I then suggest that my argument is not restricted to such fetuses, although extending my argument to more developed fetuses requires caution. PMID:26839114

  2. Culture of Piscirickettsia salmonis on enriched blood agar.

    PubMed

    Mauel, Michael J; Ware, Cynthia; Smith, Pedro A

    2008-03-01

    Piscirickettsia salmonis is the etiologic agent of piscirickettsiosis, an economically significant disease of fish. Isolation of P. salmonis by culturing on fish cell lines has been the standard technique since the initial isolation of the organism. The ability to grow P. salmonis on artificial media would relieve facilities of the cost of maintaining cell lines, permit isolation at fish culture sites with fewer contamination problems, and allow easier transport of isolates to diagnostic facilities for confirmation assays. This report describes the successful culture of P. salmonis on enriched blood agar. PMID:18319435

  3. How do microorganisms influence trace element uptake by plants? Screening in an agar model rhizosphere.

    NASA Astrophysics Data System (ADS)

    Marchetti, M.; Robinson, B. H.; Evangelou, M. W. H.; Vachey, A.; Schwitzguebel, J. P.; Bernier-Latmani, R.; Schulin, R.

    2009-04-01

    Trace elements (TE) are essential for humans and plants, but they may be toxic if their concentration is too high. For this reason, the management of TE in soils is very important. In some cases it may be necessary to increase the uptake of nutrients or TE by plants, for example in a biofortification perspective. Conversely, in some other cases TE uptake by plants should be decreased, for instance to avoid heavy metals entering the food chain via edible crops. Microorganisms living in the rhizosphere affect trace element (TE) uptake by plants. However, due to the complexity of this space and the variety of microorganisms that occur there, it is difficult to isolate the effect of any particular strain. To overcome this hurdle, we developed a system in which we grew plants under sterile conditions in agar and inoculated their rhizosphere with a single, well-defined microbial strain. For many years, agar has been used as a growth substrate for microorganisms and plant tissues. It is cheap, easy to use, and can be autoclaved to ensure its sterility. Because of its widespread use, an experiment conducted using this substrate can be reproduced under the same conditions in any laboratory. In contrast to soil, there is little interaction between the trace elements and the agar matrix. There are many studies investigating the influence of microorganisms on TE uptake by plants. However, so far only a small variety of microorganisms has been tested on few plant species. Therefore, the first objective of our research was to develop a method to rapidly screen a large variety of microorganisms on various plant species. Once this goal was achieved, we sought to study the effect of single, well-defined microbial strains on TE uptake by sunflower and wheat. The substrate for plants growth was a 10% agar solution prepared with modified Hoagland's solution and a TE solution containing 1 mg/kg Pb and molar equivalents of Cu, Ni and Zn. The agar solution was autoclaved and poured into

  4. Standard Nutrient Agar 1 as a substitute for blood-supplemented Müller-Hinton agar for antibiograms in developing countries.

    PubMed

    Niederstebruch, N; Sixt, D

    2013-02-01

    In the industrial world, the agar diffusion test is a standard procedure for the susceptibility testing of bacteria isolates. Beta-hemolytic Streptococcus spp. are tested with Müller-Hinton agar supplemented with 5 % blood, a so-called blood agar. The results are interpreted using standardized tables, which only exist for this type of nutrient matrix. Because of a number difficulties, both with respect to technical issues and to manual skills, blood agar is not a feasible option in many developing countries. Beta-hemolytic Streptococcus spp. also grow on Standard Nutrient Agar 1 (StNA1). This suggests using that type of nutrient medium for running agar diffusion tests. However, there are no standardized tables that can be used for interpreting the diameters of the zones of inhibition on StNA1 1. Using the existing standardized tables for blood agar to interpret cultures on StNA1 1 would be of great benefit under such circumstances where blood agar is not available. With this in mind, we conducted comparative tests to evaluate the growth characteristics of beta-hemolytic Streptococcus spp. on StNA1 1 compared to Müller-Hinton agar supplemented with 5 % sheep blood. In this study, we were able to show that beta-hemolytic Streptococcus spp. develop similar zones of inhibition on blood agar and on StNA1 1. Therefore, it is suggested that, for the interpretation of antibiograms of beta-hemolytic Streptococcus spp. performed on StNA1 1, the standard tables for blood agar can be used.

  5. Standard Nutrient Agar 1 as a substitute for blood-supplemented Müller-Hinton agar for antibiograms in developing countries.

    PubMed

    Niederstebruch, N; Sixt, D

    2013-02-01

    In the industrial world, the agar diffusion test is a standard procedure for the susceptibility testing of bacteria isolates. Beta-hemolytic Streptococcus spp. are tested with Müller-Hinton agar supplemented with 5 % blood, a so-called blood agar. The results are interpreted using standardized tables, which only exist for this type of nutrient matrix. Because of a number difficulties, both with respect to technical issues and to manual skills, blood agar is not a feasible option in many developing countries. Beta-hemolytic Streptococcus spp. also grow on Standard Nutrient Agar 1 (StNA1). This suggests using that type of nutrient medium for running agar diffusion tests. However, there are no standardized tables that can be used for interpreting the diameters of the zones of inhibition on StNA1 1. Using the existing standardized tables for blood agar to interpret cultures on StNA1 1 would be of great benefit under such circumstances where blood agar is not available. With this in mind, we conducted comparative tests to evaluate the growth characteristics of beta-hemolytic Streptococcus spp. on StNA1 1 compared to Müller-Hinton agar supplemented with 5 % sheep blood. In this study, we were able to show that beta-hemolytic Streptococcus spp. develop similar zones of inhibition on blood agar and on StNA1 1. Therefore, it is suggested that, for the interpretation of antibiograms of beta-hemolytic Streptococcus spp. performed on StNA1 1, the standard tables for blood agar can be used. PMID:22926453

  6. Borelli's lactritmel agar induces conidiation in rare-macroconidia producing dermatophytic fungi.

    PubMed

    Ilkit, Macit; Gümral, Ramazan; Döğen, Aylin

    2012-10-01

    Macroconidia are among the most important indicators used to identify dermatophytic fungi, but several do not usually sporulate and/or produce macroconidia on Sabouraud glucose agar. Specifically, Microsporum audouinii, M. ferrugineum, Trichophyton concentricum, T. schoenleinii, T. verrucosum, and T. violaceum (including T. soudanense and T. yaoundei) rarely form macroconidia and, therefore, cannot be easily identified. In this study, we investigated the production of macroconidia on nine common laboratory media, including Borelli's lactritmel agar (BLA), modified Borelli's lactritmel agar (MBLA), brain heart infusion agar (BHIA), Christensen's urease agar in Petri dishes (UPA), cornmeal dextrose agar (CMDA), Lowenstein-Jensen agar (LJA), malt extract agar (MEA), oatmeal agar (OA), and potato dextrose agar (PDA). The performance of these media was evaluated using 18 rare-macroconidia producing isolates, including representative of the six species mentioned above. All cultures in this study were incubated at 26°C on the bench, and conidia formation on each was investigated at 5, 10, 15, 20, 25, and 30 days of incubation. BLA apparently improved macroconidia production after 15 days and was the most useful nutrient agar medium to induce these phenotypic characters in daily practice, closely followed by OA, PDA, and MBLA. PMID:22563856

  7. Physicochemical properties of biodegradable polyvinyl alcohol-agar films from the red algae Hydropuntia cornea.

    PubMed

    Madera-Santana, Tomás J; Robledo, Daniel; Freile-Pelegrín, Yolanda

    2011-08-01

    Agar obtained from the red alga Hydropuntia cornea was blended with polyvinyl alcohol (PVOH) in order to produce biodegradable films. In this study, we compare the properties of biopolymeric films formulated with agars extracted from H. cornea collected at different seasons (rainy and dry) in the Gulf of Mexico coast and PVOH as synthetic matrix. The films were prepared at different agar contents (0%, 25%, 50%, 75%, and 100%) and their optical, mechanical, thermal, and morphological properties analyzed. The tensile strength of PVOH-agar films increased when agar content was augmented. The formulation with 50% agar from rainy season (RS) had a significant higher tensile strength when compared to those from dry season (DS; p < 0.05). Tensile modulus also displayed an increasing trend and likewise, for 50% and 75% agar blends from RS showed higher values than those from DS (p < 0.05). In contrast, elongation at break decreased as the agar content increased, independently of the season. Environmental scanning electron microscopy images of PVOH-agar 75% biofilms from RS showed a homogeneous structure with good interfacial adhesion between the two components. The changes evidenced in the FTIR spectrum of this blend suggest that hydrogen bonding is taking place between the agar ether linkages (C-O-C) and the hydroxyl groups (OH) of the PVOH. Based on the above mentioned results, blends of PVOH and 75% agar from H. cornea collected in rainy season showed good properties for applications in the biodegradable packaging industry.

  8. [Clinical utility of Pourmedia GBS agar on screening for vaginal colonization of Group B Streptococcus].

    PubMed

    Kaneda, Mitsunori; Nagasaki, Hiromi; Tasaki, Megumi; Kamiyama, Kiyoshi

    2014-01-01

    Group B Streptococcus (GBS) are normal flora of the vagina and intestinal, but if the pregnant woman was infected with GBS in the vagina, miscarriage or premature would occur or the newborn would be developed to severe GBS infection. It is recommended that the inspection of GBS on all pregnant women by Japan Society of Obstetrics and Gynecology (JSOG) and Center for Disease Control and Prevention (CDC). We examined the comparison of detection rate between Pourmedia GBS agar (Eiken Chemical Co., Ltd.) and Nissui Separated Plate Sheep Blood Agar/BTB Lactose Agar medium (Nissui Pharmaceutical Co., Ltd.) on 112 sample. The positive rate of Pourmedia GBS agar was 21.4% (24/112 samples), Whereas Nissui Separated Plate Sheep Blood Agar/BTB Lactose Agar medium was 17.8% (20/112 samples). It was found that the detection rate was improved by using Pourmedia GBS agar on GBS screening test of vaginal swab.

  9. Usefulness of Chromogenic CromoCen® AGN agar medium for the identification of the genus Aeromonas: Assessment of faecal samples.

    PubMed

    Aguilera-Arreola, M G; Portillo-Muñoz, M I; Rodríguez-Martínez, C; Castro-Escarpulli, G

    2012-08-01

    Selective screening media for the detection and identification of Aeromonas strains are needed to guide primary isolation procedures in the clinical laboratory. This study compared the selective CromoCen® AGN chromogenic agar medium for the detection and identification of Aeromonas strains that were isolated from various samples against the conventional selective agar media that are commonly used for the isolation of this organism in food, environmental and clinical samples. The Miles and Misra and ecometric methods were used to evaluate the microbiological performance of CromoCen® AGN chromogenic agar medium, which was shown to be satisfactory. A total of 14 reference Aeromonas strains, 44 wild strains and 106 clinical stool specimens were examined using both non-chromogenic selective agars that are commonly used for Aeromonas isolation and CromoCen® AGN agar. The latter exhibited 94.73% sensitivity and 100% specificity for the various samples. On CromoCen® AGN agar medium, Aeromonas formed colonies with light green, greenish and salmon pigments with or without a surrounding wide transparent zone (halo) of 2-3mm in diameter around the entire border. This medium is recommended for the isolation and potential identification of the Aeromonas genus.

  10. Agar Medium for Differential Enumeration of Lactic Streptococci1

    PubMed Central

    Reddy, M. S.; Vedamuthu, E. R.; Washam, C. J.; Reinbold, G. W.

    1972-01-01

    An agar medium containing arginine and calcium citrate as specific substrates, diffusible (K2HPO4) and undiffusible (CaCO3) buffer systems, and bromocresol purple as the pH indicator was developed to differentiate among lactic streptococci in pure and mixed cultures. Milk was added as the sole source of carbohydrate (lactose) and to provide growth-stimulating factors. Production of acid from lactose caused developing bacterial colonies to seem yellow. Subsequent arginine utilization by Streptococcus lactis and S. diacetilactis liberated ammonia, resulting in a localized pH shift back toward neutrality and a return of the original purple indicator hue. The effects of production of acid from lactose and ammonia were fixed around individual colonies by the buffering capacity of CaCO3. After 36 hr at 32 C in a candle oats jar, colonies of S. cremoris were yellow, whereas colonies of S. lactis and S. diacetilactis were white. S. diacetilactis, on further incubation, utilized suspended calcium citrate, and, after 6 days, the citrate-degrading colonies exhibited clear zoning against a turbid background, making them easily distinguishable from the colonies of the other two species. The medium proved suitable for quantitative differential enumeration when compared with another widely used general agar medium for lactic streptococci. Images PMID:16349952

  11. Evaluation of natural smile: Golden proportion, RED or Golden percentage

    PubMed Central

    Murthy, B. V. Sreenivasan; Ramani, Niketa

    2008-01-01

    Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field. Aim: To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital photographs and computer analysis. Material and Methods: Standardized frontal images of 56 dental students, 20 male and 36 female, were captured. Each maxillary anterior tooth was digitally measured. Once the measurements were recorded, the three theories were applied and the data was analyzed statistically. Results: The golden proportion was found to exist only in 14-25% of the subjects, between perceived maxillary anterior teeth in natural dentition. The value of RED proportion was not constant, and as one moved distally, this proportion gradually increased. Furthermore, the results revealed that golden percentage was rather constant in terms of relative tooth width. Central incisor represented 22%, lateral incisor 15% and canine 13% of the width of six maxillary anterior teeth, as viewed from the front. Conclusion: Both golden proportion and RED proportion are unsuitable methods to relate the successive width of the maxillary anterior teeth in natural dentition. However, the golden percentage theory can be applied if percentages are adjusted, taking into consideration the ethnicity of the population. PMID:20142879

  12. As a bacterial culture medium, citrated sheep blood agar is a practical alternative to citrated human blood agar in laboratories of developing countries.

    PubMed

    Russell, F M; Biribo, S S N; Selvaraj, G; Oppedisano, F; Warren, S; Seduadua, A; Mulholland, E K; Carapetis, J R

    2006-09-01

    Human blood agar (HuBA) is widely used in developing countries for the isolation of bacteria from clinical specimens. This study compared citrated sheep blood agar (CSBA) and HuBA with defibrinated horse blood agar and defibrinated sheep blood agar (DSBA) for the isolation and antibiotic susceptibility testing of reference and clinical strains of Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus. Reference and clinical strains of all organisms were diluted in brain heart infusion and a clinical specimen of cerebrospinal fluid and cultured on all agars. Viable counts, colony morphology, and colony size were recorded. Susceptibility testing for S. pneumoniae and S. pyogenes was performed on defibrinated sheep blood Mueller-Hinton agar, citrated sheep blood Mueller-Hinton agar (CSB MHA), and human blood Mueller-Hinton agar plates. For all organisms, the colony numbers were similar on all agars. Substantially smaller colony sizes and absent or minimal hemolysis were noted on HuBA for all organisms. Antibiotic susceptibility results for S. pneumoniae were similar for the two sheep blood agars; however, larger zone sizes were displayed on HuBA, and quality control for the reference strain failed on HuBA. For S. pyogenes, larger zone sizes were demonstrated on HuBA and CSBA than on DSBA. Poor hemolysis made interpretation of the zone sizes difficult on HuBA. CSBA is an acceptable alternative for the isolation of these organisms. The characteristic morphology is not evident, and hemolysis is poor on HuBA; and so HuBA is not recommended for use for the isolation or the susceptibility testing of any of these organisms. CSB MHA may be suitable for use for the susceptibility testing of S. pneumoniae.

  13. Identification of Staphylococcus aureus: DNase and Mannitol salt agar improve the efficiency of the tube coagulase test

    PubMed Central

    2010-01-01

    Background The ideal identification of Staphylococcus aureus clinical isolates requires a battery of tests and this is costly in resource limited settings. In many developing countries, the tube coagulase test is usually confirmatory for S. aureus and is routinely done using either human or sheep plasma. This study evaluated Mannitol salt agar and the deoxyribonuclease (DNase) test for improving the efficiency of the tube coagulase test in resource limited settings. The efficiency of human and sheep plasma with tube coagulase tests was also evaluated. Methods One hundred and eighty Gram positive, Catalase positive cocci occurring in pairs, short chains or clusters were subjected to growth on Mannitol salt agar, deoxyribonuclease and tube coagulase tests. Of these, isolates that were positive for at least two of the three tests (n = 60) were used to evaluate the performance of the tube coagulase test for identification of S. aureus, using PCR-amplification of the nuc gene as a gold standard. Results Human plasma was more sensitive than sheep plasma for the tube coagulase test (sensitivity of 91% vs. 81% respectively), but both plasmas had very low specificity (11% and 7% respectively). The sensitivity and specificity of the tube coagulase test (human plasma) was markedly improved when Mannitol salt agar and DNase were introduced as a tri-combination test for routine identification of Staphylococcus aureus (100% specificity and 75% sensitivity). The specificity and sensitivity of Mannitol salt agar/DNase/tube coagulase (sheep plasma) combination was 100% and 67%, respectively. Conclusion The efficiency of the tube coagulase test can be markedly improved by sequel testing of the isolates with Mannitol salt agar, DNase and Tube coagulase. There is no single phenotypic test (including tube coagulase) that can guarantee reliable results in the identification of Staphylococcus aureus. PMID:20707914

  14. How do college students solve proportion problems?

    NASA Astrophysics Data System (ADS)

    Thornton, Melvin C.; Fuller, Robert G.

    Problems which could be solved using proportional reasoning were administered nationwide by college faculty to their own science classes during a three year period. The reasoning of more than 8000 students covering three sections of the country was classified as concrete, transitional, or formal using Piagetian categories. Data from the West closely replicated that from the Midwest on similar metric conversion tasks. Student performance changed noticeably with a different problem format. The percentages of students using a ratio formula, ratio attempt, or intuitive methods of solution held approximately constant over time, task, and section of the country. The data shows the use of additive and conversion methods of solution depends upon the problem presentation.

  15. Evaluation of eight agar media for the isolation of shiga toxin-Producing Escherichia coli.

    PubMed

    Gill, Alexander; Huszczynski, George; Gauthier, Martine; Blais, Burton

    2014-01-01

    The growth characteristics of 96 shiga toxin-producing Escherichia coli (STEC) strains representing 36 different O-types (including priority O types O26, O45, O103, O111, O121, O145 and O157) on commercial and in-house agar media were studied. The ability of the strains to grow on agar media with varying selective supplement formulations was evaluated using MacConkey Agar (MAC); Rainbow® Agar O157 (RBA); Rainbow® Agar O157 with manufacturer-recommended selective supplements (RBA-NT); Rainbow® Agar O157 with USDA-recommended selective supplements (RBA-USDA); CHROMagar STEC™ (CH STEC); Tryptone Bile agar containing cefixime and tellurite (TBA-CT); Tryptone Bile agar containing cefixime, tellurite, eosin and methylene blue (TBA-EM); and VTEC agar. All of the strains were able to grow on MAC, RBA and VTEC agar, whereas a number of strains (including some non-O157 priority O types) were unable to grow on the highly selective media CH STEC, RBA-NT, RBA-USDA, TBA-EM and TBA-CT. Only RBA-NT and CH STEC exhibited significant inhibition of background flora from ground beef enrichment. Significant inhibition of background flora from beef trim enrichment was observed with RBA-NT, RBA-USDA, CH STEC, TBA-EM and VTEC agar. With exception of E. coli O157, several different colony morphologies were observed on the differential plating media among strains of the same O type, indicating that this colony morphology is not a reliable means of identifying target STEC. These results suggest that an approach to maximize the recovery of target STEC from beef enrichment cultures is dual plating on lesser (RBA, MAC, VTEC agar) and more highly (RBA-NT, CH STEC) selective agars.

  16. Characterization of Leptospiral Chemoreceptors Using a Microscopic Agar Drop Assay.

    PubMed

    Affroze, Samia; Islam, Md Shafiqul; Takabe, Kyosuke; Kudo, Seishi; Nakamura, Shuichi

    2016-08-01

    Bacterial chemotaxis is induced by sensing chemical stimuli via chemoreceptors embedded in the cytoplasmic membrane, enabling the cells to migrate toward nutrients or away from toxins. The chemoreceptors of Escherichia coli and Salmonella spp. have been well studied and are functionally classified on the basis of detectable substrates. The spirochete Leptospira possesses more than ten chemoreceptors and shows attractive or repellent responses against some sugars, amino acids, and fatty acids. However, the roles of these chemoreceptors have not been investigated. In this study, we conducted a chemotaxis assay called microscopic agar drop assay in combination with competition experiments, determining whether two kinds of attractants are recognized by the same type of chemoreceptor in the saprophytic Leptospira strain, Leptospira biflexa. Analyzing the competition effect observed between several pairs of chemicals, we found that L. biflexa senses sugars via chemoreceptors different from those that sense amino acids and fatty acids.

  17. Energy Proportionality for Disk Storage Using Replication

    SciTech Connect

    Kim, Jinoh; Rotem, Doron

    2010-09-09

    Energy saving has become a crucial concern in datacenters as several reports predict that the anticipated energy costs over a three year period will exceed hardware acquisition. In particular, saving energy for storage is of major importance as storage devices (and cooling them off) may contribute over 25 percent of the total energy consumed in a datacenter. Recent work introduced the concept of energy proportionality and argued that it is a more relevant metric than just energy saving as it takes into account the tradeoff between energy consumption and performance. In this paper, we present a novel approach, called FREP (Fractional Replication for Energy Proportionality), for energy management in large datacenters. FREP includes areplication strategy and basic functions to enable flexible energy management. Specifically, our method provides performance guarantees by adaptively controlling the power states of a group of disks based on observed and predicted workloads. Our experiments, using a set of real and synthetic traces, show that FREP dramatically reduces energy requirements with a minimal response time penalty.

  18. Detection of encapsulation in Staphylococcus aureus by use of antiserum agar.

    PubMed Central

    West, T E; Apicella, M A

    1984-01-01

    We examined an antiserum agar method to study its reliability in screening Staphylococcus aureus strains for capsule production. The encapsulated S. aureus Smith diffuse strain was compared with its nonencapsulated variant, Smith compact, in CCY medium containing 0.5% NaCl and 5.0% Smith diffuse rabbit antiserum. A halo was visible surrounding colonies of the Smith diffuse strain but not the Smith compact strain. On this same medium, the protein A-producing Cowan I strain possessed a halo that was visible on photographs. Single high-salt medium is known to inhibit protein A production, halo formation by the strains was also compared in 7.5% NaCl medium. The halo surrounding the Cowan I strain was not present when the salt content of the medium was increased. In contrast, the halo surrounding the Smith diffuse strain persisted in the 7.5% NaCl medium. By use of this medium, the antiserum agar technique may be valuable for the identification of encapsulated staphylococci without appreciable interference from protein A. Images PMID:6490810

  19. Visualization of Biosurfactant Film Flow in a Bacillus subtilis Swarm Colony on an Agar Plate.

    PubMed

    Kim, Kyunghoon; Kim, Jung Kyung

    2015-01-01

    Collective bacterial dynamics plays a crucial role in colony development. Although many research groups have studied the behavior of fluidic swarm colonies, the detailed mechanics of its motion remains elusive. Here, we developed a visualization method using submicron fluorescent beads for investigating the flow field in a thin layer of fluid that covers a Bacillus subtilis swarm colony growing on an agar plate. The beads were initially embedded in the agar plate and subsequently distributed spontaneously at the upper surface of the expanding colony. We conducted long-term live cell imaging of the B. subtilis colony using the fluorescent tracers, and obtained high-resolution velocity maps of microscale vortices in the swarm colony using particle image velocimetry. A distinct periodic fluctuation in the average speed and vorticity of flow in swarm colony was observed at the inner region of the colony, and correlated with the switch between bacterial swarming and growth phases. At the advancing edge of the colony, both the magnitudes of velocity and vorticity of flow in swarm colony were inversely correlated with the spreading speed of the swarm edge. The advanced imaging tool developed in this study would facilitate further understanding of the effect of micro vortices in swarm colony on the collective dynamics of bacteria. PMID:26343634

  20. Visualization of Biosurfactant Film Flow in a Bacillus subtilis Swarm Colony on an Agar Plate

    PubMed Central

    Kim, Kyunghoon; Kim, Jung Kyung

    2015-01-01

    Collective bacterial dynamics plays a crucial role in colony development. Although many research groups have studied the behavior of fluidic swarm colonies, the detailed mechanics of its motion remains elusive. Here, we developed a visualization method using submicron fluorescent beads for investigating the flow field in a thin layer of fluid that covers a Bacillus subtilis swarm colony growing on an agar plate. The beads were initially embedded in the agar plate and subsequently distributed spontaneously at the upper surface of the expanding colony. We conducted long-term live cell imaging of the B. subtilis colony using the fluorescent tracers, and obtained high-resolution velocity maps of microscale vortices in the swarm colony using particle image velocimetry. A distinct periodic fluctuation in the average speed and vorticity of flow in swarm colony was observed at the inner region of the colony, and correlated with the switch between bacterial swarming and growth phases. At the advancing edge of the colony, both the magnitudes of velocity and vorticity of flow in swarm colony were inversely correlated with the spreading speed of the swarm edge. The advanced imaging tool developed in this study would facilitate further understanding of the effect of micro vortices in swarm colony on the collective dynamics of bacteria. PMID:26343634

  1. Boron-10 Lined Proportional Counter Model Validation

    SciTech Connect

    Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

    2012-06-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

  2. First birth cesarean proportion: A missed indicator in controlling policies

    PubMed Central

    Safari-Faramani, Roya; Haghdoost, Ali Akbar; Nakhaei, Nouzar; Foroudnia, Shohreh; Mahmoodabadi, Zahra; Safizadeh, Mansooreh

    2016-01-01

    Background: Around one out of two mothers give births by cesarean section (CS) surgery in Iran and about half of this number is due to previous CS. Recently Health Sector Evolution (HSEP) program (started in April 2014) targets the high rate of CS in Iran. To assess the impact of the interventions, we emphasized that the First Birth Cesarean (FBC) proportion is one of the main indicators to assess the controlling programs. Methods: Data on the mode of delivery were collected in Kerman province between 21 March and 20 March 2015 classified by hospital ownership. FBC proportion is defined as the number of CS in the first pregnancies divided by the total number of first births. Chi-square test for trend was used to assess the trends. Results: Total number of births was around 34000. There were 8.9 and 13.1 percent reduction in CS and FBC proportion respectively. CS proportion was 54.5 at the end of the first quarter of the studied period and reached to 49.6 at the end of the period (p<0.0001). Also, FBC proportion was 54.1 percent at first and reached to 47 percent at the end of the study period. The main reason for CS was due to previous CS. At the hospital level, the highest reduction in CS and FBC proportion were in public hospitals. Conclusion: Results suggested more reduction in FBC proportion than the CS proportion, so this is a very good sign since more potential CS cases will be prevented. As repeated CS is one of the main indications for the operation, in the short term, even effective policies may change the overall proportion slightly, while the FBC proportion is more sensitive to reflect the impacts. Therefore, it is necessary to target the main fuel to reduce CS proportion effectively. PMID:27579285

  3. Broth and agar hop-gradient plates used to evaluate the beer-spoilage potential of Lactobacillus and Pediococcus isolates.

    PubMed

    Haakensen, M; Schubert, A; Ziola, B

    2009-03-15

    Identification of the beer-spoilage Lactobacillus and Pediococcus bacteria has largely taken two approaches; identification of spoilage-associated genes or identification of specific species of bacteria regardless of ability to grow in beer. The problem with these two approaches is that they are either overly inclusive (i.e., detect all bacteria of a given species regardless of spoilage potential) or overly selective (i.e., rely upon individual, putative spoilage-associated genes). Our goal was to design a method to assess the ability of Lactobacillus and Pediococcus to spoil beer that is independent of speciation or genetic background. In searching for a method by which to differentiate between beer-spoilage bacteria and bacteria that cannot grow in beer, we explored the ability of lactobacilli and pediococci isolates to grow in the presence of varying concentrations of hop-compounds and ethanol in broth medium versus on agar medium. The best method for differentiating between bacteria that can grow in beer and bacteria that do not pose a threat as beer-spoilage organisms was found to be a hop-gradient agar plate containing ethanol. This hop-gradient agar plate technique provides a rapid and simple solution to the dilemma of assessing the ability of Lactobacillus and Pediococcus isolates to grow in beer, and provides new insights into the different strategies used by these bacteria to survive under the stringent conditions of beer.

  4. Assessment of oxacillin salt agar for detection of MRSA identified by presence of the mecA gene.

    PubMed

    Kobayashi, Y; Kizaki, M; Kawakami, Y; Uchida, H; Ikeda, Y

    1993-04-01

    To assess the screening method for detection of methicillin-resistant Staphylococcus aureus recommended by Thornsberry and McDougal J. Clin Microbiol 1983; 18: 1084-1901, the growth of S. aureus and Staphylococcus epidermidis strains on Mueller Hinton agar containing 4% NaCl and 6 mg l-1 oxacillin, after 24 h incubation at 35 degrees C, was investigated. The strains used for this study were characterized for possession of the mecA gene by the polymerase chain reaction. All 39 strains of S. aureus with the mecA gene grew on this agar, and all 12 strains of S. aureus without the mecA gene did not grow. On the other hand, three of 12 strains of S. epidermidis did not grow on this agar, although all these strains possessed the mecA gene. These results suggest that Thornsberry and McDougal's screening method is suitable for detecting S. aureus strains with mecA gene. Introduction of this method, to detect methicillin-resistant S. aureus more precisely, is simple and cheap for any laboratory in any part of the world.

  5. Assessment of oxacillin salt agar for detection of MRSA identified by presence of the mecA gene.

    PubMed

    Kobayashi, Y; Kizaki, M; Kawakami, Y; Uchida, H; Ikeda, Y

    1993-04-01

    To assess the screening method for detection of methicillin-resistant Staphylococcus aureus recommended by Thornsberry and McDougal J. Clin Microbiol 1983; 18: 1084-1901, the growth of S. aureus and Staphylococcus epidermidis strains on Mueller Hinton agar containing 4% NaCl and 6 mg l-1 oxacillin, after 24 h incubation at 35 degrees C, was investigated. The strains used for this study were characterized for possession of the mecA gene by the polymerase chain reaction. All 39 strains of S. aureus with the mecA gene grew on this agar, and all 12 strains of S. aureus without the mecA gene did not grow. On the other hand, three of 12 strains of S. epidermidis did not grow on this agar, although all these strains possessed the mecA gene. These results suggest that Thornsberry and McDougal's screening method is suitable for detecting S. aureus strains with mecA gene. Introduction of this method, to detect methicillin-resistant S. aureus more precisely, is simple and cheap for any laboratory in any part of the world. PMID:8099927

  6. Estimation of lithofacies proportions using well and well test data

    SciTech Connect

    Hu, L.Y.; Blanc, G.; Noetinger, B.

    1996-12-31

    A crucial step of the commonly used geostatistical methods for modeling heterogeneous reservoirs (e.g. the sequential indicator simulation and the truncated Gaussian functions) is the estimation of the lithofacies local proportion (or probability density) functions. Well-test derived permeabilities show good correlation with lithofacies proportions around wells. Integrating well and well-test data in estimating lithofacies proportions could permit the building of more realistic models of reservoir heterogeneity. However this integration is difficult because of the different natures and measurement scales of these two types of data. This paper presents a two step approach to integrating well and well-test data into heterogeneous reservoir modeling. First lithofacies proportions in well-test investigation areas are estimated using a new kriging algorithm called KISCA. KISCA consists in kriging jointly the proportions of all lithofacies in a well-test investigation area so that the corresponding well-test derived permeability is respected through a weighted power averaging of lithofacies permeabilities. For multiple well-tests, an iterative process is used in KISCA to account for their interaction. After this, the estimated proportions are combined with lithofacies indicators at wells for estimating proportion (or probability density) functions over the entire reservoir field using a classical kriging method. Some numerical examples were considered to test the proposed method for estimating lithofacies proportions. In addition, a synthetic lithofacies reservoir model was generated and a well-test simulation was performed. The comparison between the experimental and estimated proportions in the well-test investigation area demonstrates the validity of the proposed method.

  7. Effect of Different Commerical Agar Preparations on the Inhibitory Activities of Phenols

    PubMed Central

    Sands, J. G.; Bennett, E. O.

    1966-01-01

    The minimal inhibitory concentrations of 11 phenolic inhibitors were compared in five commercial agars and in nutrient broth. It was found that the brand of agar affected the end point obtained for a particular inhibitor, and that the degree of antagonism varied with each compound studied. The results indicate that there are at least two deleterious factors present in agar, one of which is water-soluble and one which is not. The major portion of the total antagonism was due to the water-soluble factor, which could be removed by washing the agar in warm distilled water prior to use in the test medium. PMID:5959856

  8. Detection of toxigenic isolates of Aspergillus flavus and related species on coconut cream agar.

    PubMed

    Dyer, S K; McCammon, S

    1994-01-01

    A new readily-prepared medium, coconut cream agar, was developed for the detection of aflatoxin production by isolates of Aspergillus flavus and related species. Coconut cream agar, which comprised coconut cream (50%) and agar (1.5%), detected isolates of A. flavus more effectively than the synthetic media tested and was as effective as media containing desiccated coconut. Fluorescence colouring of colonies grown on coconut cream agar could be used to differentiate A. flavus from A. parasiticus and A. nomius. In addition, conidial colour of A. flavus and A. nomius was quite distinct from that of A. parasiticus.

  9. Isolation of Shiga toxin-producing Escherichia coli from fresh produce using STEC heart infusion washed blood agar with mitomycin-C.

    PubMed

    Lin, Andrew; Nguyen, Lam; Clotilde, Laurie M; Kase, Julie A; Son, Insook; Lauzon, Carol R

    2012-11-01

    The ability to detect and isolate Shiga toxin-producing Escherichia coli (STEC) remains a major challenge for food microbiologists. Although methods based on nucleic acids and antibodies have improved detection of STECs in foods, isolation of these bacteria remains arduous. STEC isolation is necessary for matching food, environmental, and clinical isolates during outbreak investigations and for distinguishing between pathogenic and nonpathogenic organisms. STEC heart infusion washed blood agar with mitomycin-C (SHIBAM) is a modification of washed sheep blood agar prepared by adding mitomycin-C and optimizing both the washed blood and base agar to better isolate STECs. Most STEC isolates produce a zone of hemolysis on SHIBAM plates and are easily distinguishable from background microbiota. Here, we present data supporting the use of SHIBAM to isolate STECs from fresh produce. SHIBAM was tested for accuracy in identifying STECs (365 of 410 STEC strains were hemolytic, and 63 of 73 E. coli strains that did not produce Shiga toxin were not hemolytic) and for recovery from artificially inoculated fresh produce (11 of 24 romaine lettuce samples and 6 of 24 tomato samples). STEC recovery with SHIBAM agar was greatly improved when compared with recovery on Levine's eosin-methylene blue agar as a reference method.

  10. A rapid detection of multidrug-resistant Mycobacterium tuberculosis by a nitrate reductase assay on blood agar.

    PubMed

    Coban, Ahmet Yilmaz; Cayci, Yeliz Tanriverdi; Deveci, Aydin; Akgunes, Alper; Uzun, Meltem; Durupinar, Belma

    2011-05-01

    The susceptibility of 49 Mycobacterium tuberculosis clinical isolates to isoniazid (INH) and rifampisin (RIF) (28 multi-drug resistant-tuberculosis samples) was determined by a nitrate reductase assay (NRA) on blood agar. Agreement between the NRA and other testing methods was found to be 93.8% for both INH and RIF. The sensitivity, specificity, positive predictive value and negative predictive value for INH were 92.8%, 94.2%, 86.6% and 97%, respectively. The sensitivity, specificity, positive predictive value and negative predictive value for RIF were 90.4%, 96.4%, 95% and 93.1%. In conclusion, we show here that blood agar can be used effectively for the NRA test.

  11. Glucose-sucrose-potassium tellurite-bacitracin agar, an alternative to mitis salivarius-bacitracin agar for enumeration of Streptococcus mutans.

    PubMed Central

    Tanzer, J M; Börjesson, A C; Laskowski, L; Kurasz, A B; Testa, M

    1984-01-01

    An agar medium for selective recovery and enumeration of Streptococcus mutans was developed as an alternative to mitis salivarius-bacitracin (MSB) agar. Combinations of dyes, antibiotics, and tellurite were added to a nonselective medium which, because of its sucrose content, allowed easy recognition of S. mutans colonies. Candle jar incubation for 2 days, by comparison with anaerobic incubation, reduced background flora but did not diminish S. mutans recoveries from clinical samples. Quantitative comparisons were made of the simultaneous recoveries of a number of authentic S. mutans serotype representatives and fresh clinical isolates, using various glucose-sucrose-potassium tellurite-bacitracin (GSTB) formulations and mitis salivarius, MSB, and blood agars. Mitis salivarius counts were not detectably different from blood counts, but counts on MSB were distinctly lower. A formulation of the new medium containing 5% glucose 5% sucrose, 0.001% potassium tellurite, 0.3 U of bacitracin per ml (hence GSTB), and 2% agar gave recoveries nearly equal to those on mitis salivarius agar and much greater than those on MSB. The medium yielded readily recognized S. mutans colonies and facilitated detection of intracellular polysaccharide formers upon flooding with I2 reagent. Freshly isolated serotype c, E, and f colonies could often be distinguished from serotype d and g colonies, a distinction made reliable by testing for intracellular polysaccharide. A study of 300 salivary samples revealed GSTB to give significantly higher recoveries than MSB. About 72% of all samples were substantially underestimated for S. mutans with MSB, and 6.7% of samples were falsely negative for S. mutans with MSB. Recovery of background flora on GSTB was as low or lower than on MSB, and both types of agar could be stored for at least 9 weeks without notable change of selectivity. Thus, GSTB agar appears to be simple and reliable to use and requires no anaerobic incubation. Caution is voiced about

  12. Goodness-of-fit test for proportional subdistribution hazards model.

    PubMed

    Zhou, Bingqing; Fine, Jason; Laird, Glen

    2013-09-30

    This paper concerns using modified weighted Schoenfeld residuals to test the proportionality of subdistribution hazards for the Fine-Gray model, similar to the tests proposed by Grambsch and Therneau for independently censored data. We develop a score test for the time-varying coefficients based on the modified Schoenfeld residuals derived assuming a certain form of non-proportionality. The methods perform well in simulations and a real data analysis of breast cancer data, where the treatment effect exhibits non-proportional hazards.

  13. Proportionality: a valid alternative to correlation for relative data.

    PubMed

    Lovell, David; Pawlowsky-Glahn, Vera; Egozcue, Juan José; Marguerat, Samuel; Bähler, Jürg

    2015-03-01

    In the life sciences, many measurement methods yield only the relative abundances of different components in a sample. With such relative-or compositional-data, differential expression needs careful interpretation, and correlation-a statistical workhorse for analyzing pairwise relationships-is an inappropriate measure of association. Using yeast gene expression data we show how correlation can be misleading and present proportionality as a valid alternative for relative data. We show how the strength of proportionality between two variables can be meaningfully and interpretably described by a new statistic ϕ which can be used instead of correlation as the basis of familiar analyses and visualisation methods, including co-expression networks and clustered heatmaps. While the main aim of this study is to present proportionality as a means to analyse relative data, it also raises intriguing questions about the molecular mechanisms underlying the proportional regulation of a range of yeast genes.

  14. Agar Diffusion Procedures for Susceptibility Testing of Malassezia pachydermatis: Evaluation of Mueller-Hinton Agar Plus 2 % Glucose and 0.5 µg/ml Methylene Blue as the Test Medium.

    PubMed

    Pasquetti, M; Chiavassa, E; Tizzani, P; Danesi, P; Peano, A

    2015-10-01

    Aim of this study was to verify whether Mueller-Hinton agar supplemented with 2 % glucose and methylene blue (MH-GM), which is used for disk diffusion susceptibility testing of Candida species by the Clinical and Laboratory Standards Institute, is suitable for testing Malassezia pachydermatis. A variant of the disk diffusion procedure utilizing a 9-mm tablet was used to test 31 isolates against clotrimazole and miconazole using MH-GM as test medium. The MH-GM agar optimally supported the growth of all M. pachydermatis isolates, provided that the yeast inoculum was prepared with a lipid source (Tween 40 and 80). Zone edges were frequently definite and clear, facilitating the measurement of zone size and minimizing subjectivity. The inhibition zones correlated with MIC values obtained in a broth dilution assay. The agar diffusion method with MH-GM as the test medium appears as a suitable procedure for testing the susceptibility of M. pachydermatis to CTZ and MCZ in clinical laboratories. This test format may allow processing a large number of isolates in epidemiological studies. This may in turn facilitate clarifying to what extent the problem "drug resistance" accounts for cases of treatment failure in dogs with Malassezia otitis and dermatitis. PMID:26138434

  15. System training and assessment in simultaneous proportional myoelectric prosthesis control

    PubMed Central

    2014-01-01

    Background Pattern recognition control of prosthetic hands take inputs from one or more myoelectric sensors and controls one or more degrees of freedom. However, most systems created allow only sequential control of one motion class at a time. Additionally, only recently have researchers demonstrated proportional myoelectric control in such systems, an option that is believed to make fine control easier for the user. Recent developments suggest improved reliability if the user follows a so-called prosthesis guided training (PGT) scheme. Methods In this study, a system for simultaneous proportional myoelectric control has been developed for a hand prosthesis with two motor functions (hand open/close, and wrist pro-/supination). The prosthesis has been used with a prosthesis socket equivalent designed for normally-limbed subjects. An extended version of PGT was developed for use with proportional control. The control system’s performance was tested for two subjects in the Clothespin Relocation Task and the Southampton Hand Assessment Procedure (SHAP). Simultaneous proportional control was compared with three other control strategies implemented on the same prosthesis: mutex proportional control (the same system but with simultaneous control disabled), mutex on-off control, and a more traditional, sequential proportional control system with co-contractions for state switching. Results The practical tests indicate that the simultaneous proportional control strategy and the two mutex-based pattern recognition strategies performed equally well, and superiorly to the more traditional sequential strategy according to the chosen outcome measures. Conclusions This is the first simultaneous proportional myoelectric control system demonstrated on a prosthesis affixed to the forearm of a subject. The study illustrates that PGT is a promising system training method for proportional control. Due to the limited number of subjects in this study, no definite conclusions can be

  16. Subculture on potato dextrose agar as a complement to the broth microdilution assay for Malassezia pachydermatis.

    PubMed

    Prado, Marilena R; Brito, Erika H S; Brilhante, Raimunda S N; Cordeiro, Rossana A; Leite, João J G; Sidrim, José J C; Rocha, Marcos F G

    2008-10-01

    The main aim of this study was to verify the efficacy of subculture on potato dextrose agar (PDA) as a complement to the in vitro susceptibility test for Malassezia pachydermatis strains by a broth microdilution method, as well as to determine the MIC and MFC of azole derivatives, amphotericin B and caspofungin. The microdilution assay was performed in 96-well plates using a modified RPMI 1640 medium. The M. pachydermatis strains were resistant to caspofungin. All strains (n=50) had shown MIC values of <0.03, <0.03, 2.0, 4.0 and 4.0 microg/ml for itraconazole, ketoconazole, voriconazole, fluconazole and amphotericin B, respectively. Thus, the subculture on PDA improved the analysis of the in vitro antifungal susceptibility of M. pachydermatis.

  17. Proportional Reasoning and the Visually Impaired

    ERIC Educational Resources Information Center

    Hilton, Geoff; Hilton, Annette; Dole, Shelley L.; Goos, Merrilyn; O'Brien, Mia

    2012-01-01

    Proportional reasoning is an important aspect of formal thinking that is acquired during the developmental years that approximate the middle years of schooling. Students who fail to acquire sound proportional reasoning often experience difficulties in subjects that require quantitative thinking, such as science, technology, engineering, and…

  18. CCSSM Challenge: Graphing Ratio and Proportion

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn

    2013-01-01

    A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…

  19. Working Memory Mechanism in Proportional Quantifier Verification

    ERIC Educational Resources Information Center

    Zajenkowski, Marcin; Szymanik, Jakub; Garraffa, Maria

    2014-01-01

    The paper explores the cognitive mechanisms involved in the verification of sentences with proportional quantifiers (e.g. "More than half of the dots are blue"). The first study shows that the verification of proportional sentences is more demanding than the verification of sentences such as: "There are seven blue and eight yellow…

  20. Use of cefoperazone MacConkey agar for selective isolation of Laribacter hongkongensis.

    PubMed

    Lau, Susanna K P; Woo, Patrick C Y; Hui, Wai-ting; Li, Maria W S; Teng, Jade L L; Que, Tak-Lun; Luk, Wei-Kwang; Lai, Raymond W M; Yung, Raymond W H; Yuen, Kwok-yung

    2003-10-01

    A new selective medium, cefoperazone MacConkey agar (CMA), was developed for primary isolation of Laribacter hongkongensis from stool. Its performance in quantitative recovery and in a clinical evaluation of 4,741 human diarrheal stool specimens was superior to that of charcoal cefoperazone deoxycholate agar. In addition, with CMA, Arcobacter butzleri was unexpectedly isolated from the stools of six patients.

  1. Ceftibuten-containing agar plate for detecting group B streptococci with reduced penicillin susceptibility (PRGBS).

    PubMed

    Kamiya, Chitose; Kimura, Kouji; Doyama, Yo; Miyazaki, Akira; Morimoto, Makiko; Banno, Hirotsugu; Nagano, Noriyuki; Jin, Wanchun; Wachino, Jun-ichi; Yamada, Keiko; Arakawa, Yoshichika

    2015-08-01

    Penicillins remain first-line agents for treatment of group B Streptococcus (Streptococcus agalactiae; GBS) infections; however, several reports have confirmed the existence of GBS with reduced penicillin susceptibility (PRGBS). Because no selective agar plates for detection of PRGBS are available to date, in this investigation, we developed the selective agar plate for detection of PRGBS. We used 19 genetically well-confirmed PRGBS isolates and 38 penicillin-susceptible GBS isolates identified in Japan. For preparation of trial PRGBS-selective agar plates, we added 1 of antimicrobial agents (among oxacillin, ceftizoxime, and ceftibuten) to a well-established GBS-selective agar plate. Among 12 trial PRGBS-selective agar plates, Muller-Hinton agar containing 128 μg/mL ceftibuten with 5% sheep blood, 8 μg/mL gentamicin, and 12 μg/mL nalidixic acid was the most appropriate selective agar for PRGBS, showing 100% sensitivity and 81.6% specificity. In cases of potential nosocomial spread of PRGBS, the selective agar plate could be useful and reliable.

  2. Evaluation of a chromogenic agar for detection of group B streptococcus in pregnant women.

    PubMed

    Craven, Robin R; Weber, Carol J; Jennemann, Rebecca A; Dunne, W Michael

    2010-09-01

    We compared ChromID Strepto B agar (STRB; bioMérieux, Inc.), a selective and differential medium for group B streptococcus, with culture using neomycin-nalidixic acid agar (NNA) and LIM broth. STRB alone was more sensitive (87.7%) than NNA alone (79.0%), while each had a sensitivity of 100% when used in conjunction with LIM broth.

  3. Effect of refrigerated storage on cefaclor in Mueller-Hinton agar.

    PubMed Central

    Surprenant, A M; Preston, D A

    1985-01-01

    Cefaclor is less stable than most cephalosporins in media at 35 degrees C. We demonstrated that the activity of cefaclor in Mueller-Hinton agar diminishes continuously at 4 degrees C, resulting in a loss of two-thirds of the activity within 21 days. We recommend that agar dilution plates for this cephalosporin be prepared on the day of their use. PMID:3968200

  4. High Concentrations of Manganese in Mueller-Hinton Agar Increase MICs of Tigecycline Determined by Etest▿

    PubMed Central

    Fernández-Mazarrasa, Carlos; Mazarrasa, Olav; Calvo, Jorge; del Arco, Asunción; Martínez-Martínez, Luis

    2009-01-01

    MICs of tigecycline determined by Etest were 4 to 12 times (three ATCC strains) and 2 to 8 times (50 clinical isolates) higher in Mueller-Hinton agar from Merck than in Mueller-Hinton agar from either Oxoid or Difco. This was related to a much higher concentration of manganese in the medium from Merck. PMID:19144806

  5. Effects of season on the yield and quality of agar from Gracilaria species (Gracilariaceae, Rhodophyta).

    PubMed

    Marinho-Soriano, E; Bourret, E

    2003-12-01

    The effect of season on yield and physical properties of agars extracted from Gracia gracilis and G. bursa-pastoris were determined. The agar yield from G. gracilis was maximum during spring (30%) and minimum during autumn (19%). In G. bursa-pastoris, the agar yield was greatest in summer (36%) and lowest in winter (23%). Agar yield from G. bursa-pastoris was positively correlated with temperature (r=0.94; P<0.01) and salinity (r=0.97; P<0.01) and negatively with nitrogen content (r=-0.93; P<0.01). Agar gel strengths fluctuated from 229 to 828 gcm(-2) and 23 to 168 gcm(-2) for G. gracilis and G. bursa-pastoris, respectively. The gelling temperature showed significant seasonal variation for both species. Chemical analysis of agar from the two seaweeds indicated variation in 3,6-anhydrogalactose and sulfate content (P<0.01). Furthermore, there was an inverse correlation between the two chemical variables. In general, agar extracted from G. gracilis possessed better qualities than agar extracted from G. bursa-pastoris and can be considered a candidate for industrial use.

  6. Development of novel agar media for isolating guaiacol producing Alicyclobacillus spp.

    PubMed

    Chang, S S; Park, S H; Kang, D H

    2013-06-01

    The purpose of this study is to develop a selective and differential medium (SK2 agar) for isolating guaiacol producing Alicyclobacillus. Forty-one selected dyes and vanillic acid were incorporated in SK agar for screening selective and differential agents. Two guaiacol producing (1016, 1101) and two non-guaiacol producing (19220, C-GD 1-1) Alicyclobacillus isolates were streaked onto media and color differentiation of the isolates was assessed. Among 41 tested dyes, Chrome Azurol S (CAS) allowed color differentiation of the two types of Alicyclobacillus. Colonies of guaiacol producing Alicyclobacillus isolates appeared as dark purple to royal blue color with yellow background, whereas non-guaiacol producing Alicyclobacillus isolates produced cream colored colonies with yellow background. Vanillic acid not only served as a precursor for guaiacol formation but also inhibited non-guaiacol producing Alicyclobacillus. Non-guaiacol producing isolates did not grow on SK agar containing more than 70 ppm vanillic acid, whereas the recovery of guaiacol producing isolates was unaffected. When compared with other Alicyclobacillus isolation media, not only was SK2 agar capable of selectively recovering guaiacol-producing Alicyclobacillus, the degree of growth was also approximately equal if not better than orange serum agar, potato dextrose agar, and K agar. The development of SK2 agar provides the fruit juice industry with an inexpensive, simple to use alternative for the detection of guaiacol producing Alicyclobacillus.

  7. Characteristics of thermoplastic sugar palm Starch/Agar blend: Thermal, tensile, and physical properties.

    PubMed

    Jumaidin, R; Sapuan, S M; Jawaid, M; Ishak, M R; Sahari, J

    2016-08-01

    The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10-40wt%. The thermoplastics were melt-mixed and then hot pressed at 140°C for 10min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young's modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30wt% agar content have the highest tensile strength. Higher content of agar (40wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, etc.

  8. Inhibition of Streptococcus mutans strains by different mitis-salivarius agar preparations.

    PubMed Central

    Staat, R H

    1976-01-01

    Several Streptococcus mutans strains were markedly inhibited by mitis-salivarius agar manufactured by Baltimore Biological Laboratories, but little, if any, inhibition was noted using Difco Laboratories' mitis-salivarius agar. Supplementation of the basic medium with sucrose and bacitracin for specific selection of S. mutans resulted in suppression of representative S. mutans type a strains regardless of manufacturer. PMID:1270597

  9. Characteristics of thermoplastic sugar palm Starch/Agar blend: Thermal, tensile, and physical properties.

    PubMed

    Jumaidin, R; Sapuan, S M; Jawaid, M; Ishak, M R; Sahari, J

    2016-08-01

    The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10-40wt%. The thermoplastics were melt-mixed and then hot pressed at 140°C for 10min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young's modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30wt% agar content have the highest tensile strength. Higher content of agar (40wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, etc. PMID:27177458

  10. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

    2015-01-22

    In this work, we report the successful fabrication of agar-based nanofibers by electrospinning technique, using water as solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operating at 50°C, to avoid agar gelation. Agar pure solution (1 wt%) showed inadequate spinnability regardless of the used electrospinning conditions. The addition of a co-blending polymer such as PVA (10 wt% starting solution) improved the solutions viscoelasticity and hence, the solutions spinnability. Agar/PVA solutions were prepared with different mass ratios (100/0, 50/50, 40/60, 30/70, 20/80 and 0/100) and electrospun at various sets of electrospinning conditions. Best nanofibers were obtained with 30/70 and 20/80 agar/PVA blends while samples with higher agar contents (50/50 and 40/60 agar/PVA) were harder to process and led to discontinuous fibrous mats. This first set of encouraging results can open a new window of opportunities for agar-based biomaterials in the form of nanofibers.

  11. Efficacy of agar-plate culture in detection of Strongyloides stercoralis infection.

    PubMed

    Arakaki, T; Iwanaga, M; Kinjo, F; Saito, A; Asato, R; Ikeshiro, T

    1990-06-01

    Agar-plate culture of feces using a modified petri dish proved to be highly efficient in the detection of Strongyloides stercoralis infection. Furrows left by S. stercoralis on the agar plate were distinguished readily in size from those left by Necator americanus. PMID:2352073

  12. [Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in environmental samples].

    PubMed

    Sengul, Mustafa; Ergin, Cağrı; Kartal, Tuğba

    2014-04-01

    Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C

  13. [Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in environmental samples].

    PubMed

    Sengul, Mustafa; Ergin, Cağrı; Kartal, Tuğba

    2014-04-01

    Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C

  14. Comparison of the BBL CHROMagar Staph aureus Agar Medium to Conventional Media for Detection of Staphylococcus aureus in Respiratory Samples

    PubMed Central

    Flayhart, Diane; Lema, Clara; Borek, Anita; Carroll, Karen C.

    2004-01-01

    Screening for Staphylococcus aureus has become routine in certain patient populations. This study is the first clinical evaluation of the BBL CHROMagar Staph aureus agar (CSA) medium (BD Diagnostics, Sparks, Md.) for detection of S. aureus in nasal surveillance cultures and in respiratory samples from cystic fibrosis (CF) patients. S. aureus colonies appear mauve on CSA. Other organisms are inhibited or produce a distinctly different colony color. S. aureus was identified from all media by slide coagulase, exogenous DNase, and mannitol fermentation assays. Susceptibility testing was performed using the agar dilution method. A total of 679 samples were evaluated. All samples were inoculated onto CSA. Nasal surveillance cultures were inoculated onto sheep blood agar (SBA) (BD Diagnostics), and samples from CF patients were inoculated onto mannitol salt agar (MSA) (BD Diagnostics). Of the 679 samples cultured, 200 organisms produced a mauve color on CSA (suspicious for S. aureus) and 180 were positive for S. aureus on SBA or MSA. Of 200 CSA-positive samples 191 were identified as S. aureus. Nine mauve colonies were slide coagulase negative and were subsequently identified as Staphylococcus lugdunensis (one), Staphylococcus epidermidis (three), Staphylococcus haemolyticus (one), and Corynebacterium species (four). CSA improved the ability to detect S. aureus by recovering 12 S. aureus isolates missed by conventional media. Of the 192 S. aureus isolates recovered, 122 were methicillin susceptible and 70 were methicillin resistant. Overall, the sensitivity and specificity of CSA in this study were 99.5 and 98%, respectively. There was no difference in the performance of the slide coagulase test or in susceptibility testing performed on S. aureus recovered from CSA compared to SBA or MSA. Our data support the use of CSA in place of standard culture media for detection of S. aureus in heavily contaminated respiratory samples. PMID:15297498

  15. Comparison of the BBL CHROMagar Staph aureus agar medium to conventional media for detection of Staphylococcus aureus in respiratory samples.

    PubMed

    Flayhart, Diane; Lema, Clara; Borek, Anita; Carroll, Karen C

    2004-08-01

    Screening for Staphylococcus aureus has become routine in certain patient populations. This study is the first clinical evaluation of the BBL CHROMagar Staph aureus agar (CSA) medium (BD Diagnostics, Sparks, Md.) for detection of S. aureus in nasal surveillance cultures and in respiratory samples from cystic fibrosis (CF) patients. S. aureus colonies appear mauve on CSA. Other organisms are inhibited or produce a distinctly different colony color. S. aureus was identified from all media by slide coagulase, exogenous DNase, and mannitol fermentation assays. Susceptibility testing was performed using the agar dilution method. A total of 679 samples were evaluated. All samples were inoculated onto CSA. Nasal surveillance cultures were inoculated onto sheep blood agar (SBA) (BD Diagnostics), and samples from CF patients were inoculated onto mannitol salt agar (MSA) (BD Diagnostics). Of the 679 samples cultured, 200 organisms produced a mauve color on CSA (suspicious for S. aureus) and 180 were positive for S. aureus on SBA or MSA. Of 200 CSA-positive samples 191 were identified as S. aureus. Nine mauve colonies were slide coagulase negative and were subsequently identified as Staphylococcus lugdunensis (one), Staphylococcus epidermidis (three), Staphylococcus haemolyticus (one), and Corynebacterium species (four). CSA improved the ability to detect S. aureus by recovering 12 S. aureus isolates missed by conventional media. Of the 192 S. aureus isolates recovered, 122 were methicillin susceptible and 70 were methicillin resistant. Overall, the sensitivity and specificity of CSA in this study were 99.5 and 98%, respectively. There was no difference in the performance of the slide coagulase test or in susceptibility testing performed on S. aureus recovered from CSA compared to SBA or MSA. Our data support the use of CSA in place of standard culture media for detection of S. aureus in heavily contaminated respiratory samples.

  16. Mechanical touch responses of Arabidopsis TCH1-3 mutant roots on inclined hard-agar surface

    NASA Astrophysics Data System (ADS)

    Zha, Guodong; Wang, Bochu; Liu, Junyu; Yan, Jie; Zhu, Liqing; Yang, Xingyan

    2016-01-01

    The gravity-induced mechanical touch stimulus can affect plant root architecture. Mechanical touch responses of plant roots are an important aspect of plant root growth and development. Previous studies have reported that Arabidopsis TCH1-3 genes are involved in mechano-related events, how-ever, the physiological functions of TCH1-3 genes in Arabidopsis root mechanoresponses remain unclear. In the present study, we applied an inclined hard agar plate method to produce mechanical touch stimulus, and provided evidence that altered mechanical environment could influence root growth. Furthermore, tch1-3 Arabidopsis mutants were investigated on inclined agar surfaces to explore the functions of TCH1-3 genes on Arabidopsis root mechanoresponses. The results showed that two tch2 mutants, cml24-2 and cml24-4, exhibited significantly reduced root length, biased skewing, and decreased density of lateral root. In addition, primary root length and density of lateral root of tch3 (cml12-2) was significantly decreased on inclined agar surfaces. This study indicates that the tch2 and tch3 mutants are hypersensitive to mechanical touch stimulus, and TCH2 (CML24-2 and CML24-4) and TCH3 (CML12-2) genes may participate in the mechanical touch response of Arabidopsis roots.

  17. A preliminary evaluation of a new selective agar supplemented with desferrioxamine for detection of methicillin-resistant Staphylococcus aureus.

    PubMed

    Monsen, T; Olofsson, C; Granström, S; Wiström, J

    2003-07-01

    The aim of the present study was to evaluate the performance of two new selective screening agars, Colombia agar supplemented with 1000 mg/L desferrioxamine, 5 mg/L amphotericin B, 16 mg/L polymyxin B, and 2 mg/L methicillin (CMDAP agar) or 0.5 mg/L oxacillin (CODAP agar), for detection of methicillin-resistant Staphylococcus aureus (MRSA). Both the CMDAP and the CODAP agar effectively inhibited growth of 151 isolates of coagulase-negative staphylococci (CoNS), 45 of Enterobacteriaceae and six Candida spp. examined. The sensitivity and specificity of the CMDAP and CODAP agars for detection of MRSA was calculated by comparing the growth of 52 MRSA with the inhibition of 74 mecA negative S. aureus and of 151 CoNS. The performance of the new agars was compared with four previously described MRSA screening agars. The sensitivity and specificity for detection of MRSA after incubation at 35 degrees C for 24 h was 0.94 and 0.91, respectively, for the CMDAP agar, 0.60 and 0.90 for the CODAP agar, 0.98 and 0.57 for methicillin aztreonam mannitol salt agar (MAMSA), 0.23 and 0.84 for oxacillin mannitol salt agar (OMSA), 0.48 and 0.76 for oxacillin Mueller-Hinton agar (OMHA) and 0.75 and 0.77 for lithium oxacillin mannitol salt agar (LOMSA). Agars supplemented with desferrioxamine, CMDAP and CODAP, were more specific for detecting MRSA compared with agars not supplemented with desferrioxamine. The detection rate was higher for agars supplemented with methicillin than for agars supplemented with oxacillin.

  18. Improvements in estimating proportions of objects from multispectral data

    NASA Technical Reports Server (NTRS)

    Horwitz, H. M.; Hyde, P. D.; Richardson, W.

    1974-01-01

    Methods for estimating proportions of objects and materials imaged within the instantaneous field of view of a multispectral sensor were developed further. Improvements in the basic proportion estimation algorithm were devised as well as improved alien object detection procedures. Also, a simplified signature set analysis scheme was introduced for determining the adequacy of signature set geometry for satisfactory proportion estimation. Averaging procedures used in conjunction with the mixtures algorithm were examined theoretically and applied to artificially generated multispectral data. A computationally simpler estimator was considered and found unsatisfactory. Experiments conducted to find a suitable procedure for setting the alien object threshold yielded little definitive result. Mixtures procedures were used on a limited amount of ERTS data to estimate wheat proportion in selected areas. Results were unsatisfactory, partly because of the ill-conditioned nature of the pure signature set.

  19. Proportion of recovered waterfowl bands reported

    USGS Publications Warehouse

    Geis, A.D.; Atwood, E.L.

    1961-01-01

    Data from the annual mail survey of waterfowl hunters in the United States were used to estimate the total numbers of banded waterfowl that were shot. These estimates were compared with Banding Office records to estimate the proportion of recovered bands that was reported. On the average, about two banded birds were recovered for each one reported. The proportion reported was higher for some areas and for some species than for others. The proportion reported was higher when more of the reports came through employees of conservation agencies.

  20. Evaluation of use of a new chromogenic agar in detection of urinary tract pathogens.

    PubMed

    Samra, Z; Heifetz, M; Talmor, J; Bain, E; Bahar, J

    1998-04-01

    CHROMagar Orientation, a new chromogenic medium, was evaluated for the detection and differentiation of gram-positive and gram-negative pathogenic microorganisms in 900 urine samples from hospitalized patients. Performance characteristics of the medium were evaluated in comparison to those of 5% sheep blood and MacConkey agars by direct inoculation of the urine samples on the three media. Four gram-negative and two gram-positive strains as well as one yeast control strain from the American Type Culture Collection were used to ensure quality control. CHROMagar Orientation succeeded in detecting all the urine pathogens that were detected by the reference media, including gram-negative bacilli, staphylococci, streptococci, and yeasts. Colony color and morphology on CHROMagar Orientation accurately differentiated Escherichia coli, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, and Acinetobacter spp. Owing to the similarity in the pigmentation produced by Klebsiella, Enterobacter, and Citrobacter isolates, the medium failed to distinguish among them; however, these isolates were easily recognized as coliforms because of their metallic blue coloration. Staphylococci were clearly perceptible: S. aureus and S. epidermidis grow in regular-size colonies that range from opaque white to yellowish, and S. saprophyticus produces opaque pink colonies. All streptococcus strains, including those from groups B and C, were detected. They grow as undifferentiated flat dry diffused colonies, and additional tests were required for identification. Enterococci were easily discriminated by their strong turquoise pigmentation and their typical growth on the agar's surface. Yeast grow in typical creamy wet convex colonies. The accuracy of antibiotic susceptibility determinations according to standard methods was also tested by picking isolates directly from CHROMagar Orientation. The results showed excellent correlation with those obtained with microorganisms picked from

  1. A FORTRAN program for testing trend and homogeneity in proportions.

    PubMed

    Thakur, A K; Berry, K J; Mielke, P W

    1985-01-01

    A FORTRAN program is provided for testing linear trend and homogeneity in proportions. Trend is evaluated by the Cochran-Armitage method and homogeneity is tested by an overall X2 test as well by multiple pairwise comparisons by the Fisher-Irwin exact method. The program should be easy to implement on any size of computer with a FORTRAN compiler.

  2. Working memory mechanism in proportional quantifier verification.

    PubMed

    Zajenkowski, Marcin; Szymanik, Jakub; Garraffa, Maria

    2014-12-01

    The paper explores the cognitive mechanisms involved in the verification of sentences with proportional quantifiers (e.g., "More than half of the dots are blue"). The first study shows that the verification of proportional sentences is more demanding than the verification of sentences such as: "There are seven blue and eight yellow dots". The second study reveals that both types of sentences are correlated with memory storage, however, only proportional sentences are associated with the cognitive control. This result suggests that the cognitive mechanism underlying the verification of proportional quantifiers is crucially related to the integration process, in which an individual has to compare in memory the cardinalities of two sets. In the third study we find that the numerical distance between two cardinalities that must be compared significantly influences the verification time and accuracy. The results of our studies are discussed in the broader context of processing complex sentences. PMID:24374596

  3. Proportionality, just war theory and weapons innovation.

    PubMed

    Forge, John

    2009-03-01

    Just wars are supposed to be proportional responses to aggression: the costs of war must not greatly exceed the benefits. This proportionality principle raises a corresponding 'interpretation problem': what are the costs and benefits of war, how are they to be determined, and a 'measurement problem': how are costs and benefits to be balanced? And it raises a problem about scope: how far into the future do the states of affairs to be measured stretch? It is argued here that weapons innovation always introduces costs, and that these costs cannot be determined in advance of going to war. Three examples, the atomic bomb, the AK-47 and the ancient Greek catapult, are given as examples. It is therefore argued that the proportionality principle is inapplicable prospectively. Some replies to the argument are discussed and rejected. Some more general defences of the proportionality principle are considered and also rejected. Finally, the significance of the argument for Just War Theory as a whole is discussed.

  4. Effectual detection of group B streptococci with reduced penicillin susceptibility (PRGBS) by commercially available methicillin-resistant-Staphylococcus aureus (MRSA)-selective agar.

    PubMed

    Fukigai, Shinako; Morimoto, Makiko; Kimura, Kouji; Doyama, Yo; Miyazaki, Akira; Kamiya, Chitose; Banno, Hirotsugu; Morishima, Eriko; Onoda, Tomohiro; Nagano, Noriyuki; Jin, Wanchun; Wachino, Jun-Ichi; Yamada, Keiko; Arakawa, Yoshichika

    2016-07-01

    We evaluated the feasibility and efficacy of a commercially available methicillin-resistant Staphylococcus aureus (MRSA)-selective agar, chromID(™) MRSA, to detect group B streptococci with reduced penicillin susceptibility (PRGBS) in this study. The results showed 72.4% (21/29) sensitivity and 98.4% (60/61) specificity to detect PRGBS using this method.

  5. Evaluation of blood agar microtiter plates for culturing leishmania parasites to titrate parasite burden in spleen and peripheral blood of patients with visceral leishmaniasis.

    PubMed

    Maurya, Radheshyam; Mehrotra, Sanjana; Prajapati, Vijay Kumar; Nylén, Susanne; Sacks, David; Sundar, Shyam

    2010-05-01

    Serial dilution of blood and spleen biopsy specimens, plated on Novy-MacNeal-Nicolle (NNN) blood agar using microtiter culture plates, is a sensitive and reproducible method for detection and growth of Leishmania parasites. Plates could be easily monitored, and growth could be rapidly detected. Moreover, parasite number may be estimated using this technique.

  6. Validation of the Use of Middlebrook 7H10 Agar, BACTEC MGIT 960, and BACTEC 460 12B Media for Testing the Susceptibility of Mycobacterium tuberculosis to Levofloxacin

    PubMed Central

    Sanders, Cynthia A.; Nieda, Rachel R.; Desmond, Edward P.

    2004-01-01

    Levofloxacin, the active l-isomer of the quinolone ofloxacin, is now widely accepted for treatment of multidrug-resistant tuberculosis. Because the drug is now widely used, we sought to establish susceptibility test conditions for Mycobacterium tuberculosis against levofloxacin by the traditional reference method, agar proportion (AP), the commonly used BACTEC 460 radiometric system, and the newer BACTEC MGIT 960 method. To determine the stability of levofloxacin in the two newer test systems (BACTEC 460 and BACTEC MGIT 960), media containing subinhibitory levels of levofloxacin were prepared and stored at 4 and 37°C for 14 days. The stored media were inoculated with H37Rv, and the drug activity was compared to freshly prepared media. Results show that levofloxacin is stable over the course of testing. Next, optimum levofloxacin test concentrations were determined for AP, BACTEC 460, and BACTEC MGIT 960 methods. MICs were determined for 32 pan-susceptible isolates of M. tuberculosis obtained from presumably untreated patients and 14 quinolone-resistant isolates. The levofloxacin-resistant strains either were isolated from patients who remained culture-positive despite treatment with a quinolone agent (six strains) or contained known mutations in gyrA (eight strains). Levofloxacin MICs resulted in a bimodal pattern with values for resistant strains consistently higher than those for pan-susceptible strains. Results show that levofloxacin concentrations of 2 μg/ml (BACTEC 460 and BACTEC MGIT 960) and 1 μg/ml (AP) inhibited the growth of all pan-susceptible strains while permitting the growth of all levofloxacin-resistant strains. Confirmatory tests with a subset of pan-susceptible and levofloxacin-resistant isolates validated the selected test concentrations. PMID:15528718

  7. Development of an improved selective agar medium for isolation of Yersinia pestis.

    PubMed

    Ber, Raphael; Mamroud, Emanuelle; Aftalion, Moshe; Tidhar, Avital; Gur, David; Flashner, Yehuda; Cohen, Sara

    2003-10-01

    Existing media designed for selective isolation of clinically important members of the genus Yersinia were found to be unsatisfactory for the growth and isolation of Yersinia pestis. We report the development of a new selective agar medium (termed BIN) that supports the growth of Y. pestis. The development of the formulation of this medium was based on a fluorescence screening system designed for monitoring bacterial growth on semisolid media, using a green fluorescent protein-expressing strain. High-throughput combinatorial experiments can be conducted for the quantitative evaluation of the effect of different medium components on growth. Generation of fluorescence plots in this system, using microplates, allowed the quantitative evaluation of the growth rate of Y. pestis EV76 cultures in different agar compositions. The final BIN formulation is based on brain heart infusion agar, to which the selective agents irgasan, cholate salts, crystal violet, and nystatin were introduced. It was found that BIN agar is more efficient in supporting colony formation and recovery of Y. pestis than are the conventional semisolid media MacConkey agar and Yersinia-selective agar (cefsulodin-irgasan-novobiocin agar). The advantage of BIN over other media has been also demonstrated in recovering virulent Y. pestis from the mixed bacterial populations found in decaying carcasses of infected mice. The BIN medium is suggested as a selective medium for isolation and recovery of Y. pestis from various backgrounds.

  8. Xanthan gum: an economical substitute for agar in plant tissue culture media.

    PubMed

    Jain, R; Babbar, S B

    2006-03-01

    Xanthan gum, a microbial desiccation-resistant polysaccharide prepared commercially by aerobic submerged fermentation from Xanthomonas campestris, has been successfully used as a solidifying agent for plant tissue culture media. Its suitability as a substitute to agar was demonstrated for in vitro seed germination, caulogenesis and rhizogenesis of Albizzia lebbeck, androgenesis in anther cultures of Datura innoxia, and somatic embryogenesis in callus cultures of Calliandra tweedii. Culture media used for eliciting these morphogenic responses were gelled with either 1% xanthan gum or 0.9% agar. Xanthan gum, like agar, supported all these responses.

  9. Polymer film deposition on agar using a dielectric barrier discharge jet and its bacterial growth inhibition

    NASA Astrophysics Data System (ADS)

    Tsai, T.-C.; Cho, J.; Mcintyre, K.; Jo, Y.-K.; Staack, D.

    2012-08-01

    Polymer film deposition on agar in ambient air was achieved using the helium dielectric barrier discharge jet (DBD jet) fed with polymer precursors, and the bacterial growth inhibition due to the deposited film was observed. The DBD jet with precursor addition was more efficient at sterilization than a helium-only DBD jet. On the areas where polymer films cover the agar the bacterial growth was significantly inhibited. The inhibition efficacy showed dependence on the film thickness. The DBD jet without precursor also created a modified agar layer, which may slow the growth of some bacterial strains.

  10. A note on a selective agar medium for the enumeration of Flavobacterium species in water.

    PubMed

    Flint, K P

    1985-12-01

    A selective nutrient agar medium containing kanamycin at 50 micrograms/ml was developed for the isolation and enumeration of yellow-pigmented colonies from the River Sowe, Coventry. Such organisms were shown to be members of the heterogeneous genus Flavobacterium. Typically, yellow pigmented colonies constituted less than 10% of the colonies on nutrient agar alone but up to 70% on nutrient agar plus kanamycin. This medium is a useful addition to the range of media available for the isolation and further ecological study of particular species of this important group of micro-organisms.

  11. [Comparison of the results of determining antibiotic sensitivity on AGV medium and on Mueller-Hinton and isosensitest agars].

    PubMed

    Kozlov, R S; Strachunskiĭ, L S; Livermor, D M; Stetsiuk, O U; Shavrikova, E P

    1996-01-01

    To evaluate the adequacy of AGV agar for antimicrobial susceptibility testing, the susceptibility of a range of bacteria to 10 antimicrobials on AGV, Mueller-Hinton and isoSensitest agars, all supplemented with 5 per cent lyzed horse blood was determined. Disc tests were used. In general, AGV agar gave identical susceptibility results to Mueller-Hinton and isoSensitest agars for common gram positive and gram negative bacteria with most of the tested microbials excluding sulphonamides and trimethoprim. With those latter antimicrobials inhibition zones for susceptible organisms were not formed on AGV agar whereas large zones were present on Mueller-Hinton and isoSensitest agars. This discrepancy probably can be explained by the presence of high levels of thymidine in AGV agar; too high to be corrected even by the addition of 5 per cent lysed horse blood. AGV agar is possible to use for susceptibility testing with most of the microbials excluding trimethoprim and sulphonamides.

  12. Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

    PubMed

    Tomaso, Herbert; Bartling, Carsten; Al Dahouk, Sascha; Hagen, Ralf M; Scholz, Holger C; Beyer, Wolfgang; Neubauer, Heinrich

    2006-01-01

    Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

  13. Neonothopanus gardneri: a new combination for a bioluminescent agaric from Brazil.

    PubMed

    Capelari, Marina; Desjardin, Dennis E; Perry, Brian A; Asai, Tatiane; Stevani, Cassius V

    2011-01-01

    The bioluminescent agaric, Agaricus gardneri Berk., was rediscovered recently in central Brazil. The new combination, Neonothopanus gardneri, is proposed for this long-forgotten taxon supported by morphological and molecular data.

  14. A fresh liver agar substrate for rearing small numbers of forensically important blow flies (Diptera: Calliphoridae)

    USGS Publications Warehouse

    Gruner, Susan V.; Slone, Daniel H.

    2014-01-01

    Forensically important calliphorids can be reared on a mixture of beef liver and agar. Small pieces of meat, especially fresh or frozen beef liver, will desiccate in 2–6 h, but this simple-to-make feeding substrate remains moist for at least 12 h at 25 and 30°C without desiccation, even in small (5 g) amounts. We determined the survivorship of small numbers of Chrysomya megacephala (F.) (first-instar larvae to adult eclosion) raised on 5 g of liver agar and fresh beef liver. We found that all larvae raised on 5 g of liver died due to desiccation, but survivorship on 5 g of liver agar was equivalent to that on larger (50 g) pieces of either liver agar or beef liver.

  15. Boron-10 Lined Proportional Counter Wall Effects

    SciTech Connect

    Siciliano, Edward R.; Kouzes, Richard T.

    2012-05-01

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

  16. Proportional hazards models with discrete frailty.

    PubMed

    Caroni, Chrys; Crowder, Martin; Kimber, Alan

    2010-07-01

    We extend proportional hazards frailty models for lifetime data to allow a negative binomial, Poisson, Geometric or other discrete distribution of the frailty variable. This might represent, for example, the unknown number of flaws in an item under test. Zero frailty corresponds to a limited failure model containing a proportion of units that never fail (long-term survivors). Ways of modifying the model to avoid this are discussed. The models are illustrated on a previously published set of data on failures of printed circuit boards and on new data on breaking strengths of samples of cord.

  17. [THE APPLICATION OF SELECTIVE CHROMOGENIC AGAR FOR DETECTING ENTEROBACTERIA WITH PRODUCTION OF BETA-LACTAMASES].

    PubMed

    Korobova, A G; Frolova, L N; Kliasova, G A

    2015-11-01

    The detection of enterobacteria with production of beta-lactamases of extended spectrum in selective chromogenic agar was analyzed The results ofdetection of beta-lactamases of extended spectrum was compared with "double disc" technique. The smears from mucous membrane of guttur and rectum from patients were analyzed in parallel on solid growth agar (Endo or Mac Conkey) and on selective agar CHROMagartm ESBL (CHROMagar France). The production of beta-lactamases of extended spectrum was confirmed using "double discs" technique. To exclude hyper-production of ampC beta-lactamases E-test was applied containing cefotetan and cefotetan with cloxacillin. The sampling consisted of 1552 samples from patients. The study permitted to isolate 1243 strains of enterobacteria on agar Endo or Mac Conkey and 409 strains of enterobacteria on selective agar CHROMagartm ESBL (Escherichia coli n = 226, Klebsiella pneumoniae n = 105, enterobacter spp. n = 35, Citrobacter spp. n = 21, others n = 22). The application of "double discs" technique confirmed production of beta-lactamases of extended spectrum in 386 (94%) out of 409 strains isolated on agar CHROMagartm ESBL. In 23 (6%) of strains no confirmation was established and hyper-production of ampC of beta-lactamases was established 15 out of total. Additionally, 8 were sensitive to cephalosporin of third generation. All enterobacteria isolated on agar Endo or Mac Conkey also were tested by "double discs" technique. Overall, 394 strains of enterobacteria with production of beta-lactamases of extended spectrum were obtained. On all agars (agar Endo or Mac Conkey and CHROMagartm ESBL)--263 (67%) strains; only on CHROMagartm ESBL--123 (31%) and only on agar Endo or Mac Conkey--8 (2%) (p < 0.0001). The sensitivity of selective agar CHROMagartm ESBL made up to 98% and specificity--97%. The resolution about detection of enterobacteria producing beta-lactamases of extended spectrum were submitted to clinic in 18-24 hours after arrival

  18. [THE APPLICATION OF SELECTIVE CHROMOGENIC AGAR FOR DETECTING ENTEROBACTERIA WITH PRODUCTION OF BETA-LACTAMASES].

    PubMed

    Korobova, A G; Frolova, L N; Kliasova, G A

    2015-11-01

    The detection of enterobacteria with production of beta-lactamases of extended spectrum in selective chromogenic agar was analyzed The results ofdetection of beta-lactamases of extended spectrum was compared with "double disc" technique. The smears from mucous membrane of guttur and rectum from patients were analyzed in parallel on solid growth agar (Endo or Mac Conkey) and on selective agar CHROMagartm ESBL (CHROMagar France). The production of beta-lactamases of extended spectrum was confirmed using "double discs" technique. To exclude hyper-production of ampC beta-lactamases E-test was applied containing cefotetan and cefotetan with cloxacillin. The sampling consisted of 1552 samples from patients. The study permitted to isolate 1243 strains of enterobacteria on agar Endo or Mac Conkey and 409 strains of enterobacteria on selective agar CHROMagartm ESBL (Escherichia coli n = 226, Klebsiella pneumoniae n = 105, enterobacter spp. n = 35, Citrobacter spp. n = 21, others n = 22). The application of "double discs" technique confirmed production of beta-lactamases of extended spectrum in 386 (94%) out of 409 strains isolated on agar CHROMagartm ESBL. In 23 (6%) of strains no confirmation was established and hyper-production of ampC of beta-lactamases was established 15 out of total. Additionally, 8 were sensitive to cephalosporin of third generation. All enterobacteria isolated on agar Endo or Mac Conkey also were tested by "double discs" technique. Overall, 394 strains of enterobacteria with production of beta-lactamases of extended spectrum were obtained. On all agars (agar Endo or Mac Conkey and CHROMagartm ESBL)--263 (67%) strains; only on CHROMagartm ESBL--123 (31%) and only on agar Endo or Mac Conkey--8 (2%) (p < 0.0001). The sensitivity of selective agar CHROMagartm ESBL made up to 98% and specificity--97%. The resolution about detection of enterobacteria producing beta-lactamases of extended spectrum were submitted to clinic in 18-24 hours after arrival

  19. A new chromogenic agar medium for detection of potentially virulent Yersinia enterocolitica.

    PubMed

    Weagant, Stephen D

    2008-02-01

    Several outbreaks of foodborne yersiniosis have been documented and this disease continues to be source of infections transmitted through foods. The selective agars most commonly used to isolate Yersinia enterocolitica in clinical, food and environmental samples, cefsulodin-irgasan-novobiocin (CIN) and MacConkey (MAC) agars, lack the ability to differentiate potentially virulent Y. enterocolitica from other Yersinia that may be present as well as some other bacterial spp. This study proposes the use of an agar medium, Y. enterocolitica chromogenic medium (YeCM), for isolation of potentially virulent Y. enterocolitica. This agar contains cellobiose as the fermentable sugar, a chromogenic substrate and selective inhibitors for suppression of colony formation by many competing bacteria. All strains of potentially virulent Yersinia of biotypes 1B, and biotypes 2-5 formed convex, red bulls-eye colonies on YeCM that were very similar to those described for CIN agar. However, Y. enterocolitica biotype 1A and other related Yersinia formed colonies that were purple/blue on YeCM while they formed typical red bulls-eye colonies on CIN agar. When a mixture of potentially virulent Y. enterocolitica biotype 1B, Y. enterocolitica biotype 1A and 5 other bacterial species was used to artificially contaminate tofu and then spread-plated on three selective agars, Y. enterocolitica biotype 1B colonies were easily distinguished from other strains on YeCM. However, Y. enterocolitica biotype 1B colonies were indistinguishable from many other colonies on CIN and only distinguishable from those of C. freundii on MAC. When colonies were picked and identified from these agars, typical colonies from YeCM were confirmed only as Y. enterocolitica biotype 1B. Typical colonies on CIN and MAC were found to belong to several competing species and biotypes.

  20. Genome Sequence of the Agar-Degrading Marine Bacterium Alteromonadaceae sp. Strain G7

    PubMed Central

    Kwak, Min-Jung; Song, Ju Yeon; Kim, Byung Kwon; Chi, Won-Jae; Kwon, Soon-Kyeong; Choi, Soobeom; Chang, Yong-Keun

    2012-01-01

    Here, we present the high-quality draft genome sequence of the agar-degrading marine gammaproteobacterium Alteromonadaceae sp. strain G7, which was isolated from coastal seawater to be utilized as a bioresource for production of agar-derived biofuels. The 3.91-Mb genome contains a number of genes encoding algal polysaccharide-degrading enzymes such as agarases and sulfatases. PMID:23209220

  1. Detection of Activity Responsible for Induction of the Agrobacterium tumefaciens Virulence Genes in Bacteriological Agar.

    PubMed

    Loubens, I; Chilton, W S; Dion, P

    1997-11-01

    Agrobacterium tumefaciens C58 grown on acidic medium containing glucose and solidified with bacteriological agar expressed a virB::lacZ fusion. No expression of this fusion was observed on a similar medium which was solidified with purified agarose. The fraction from bacteriological agar which was responsible for vir gene induction was extracted with methanol and partially purified by preparative thin-layer chromatography. PMID:16535740

  2. Evaluation of the Oxoid Brilliance™ CRE Agar for the detection of carbapenemase-producing Enterobacteriaceae.

    PubMed

    Cohen Stuart, J; Voets, G; Rottier, W; Voskuil, S; Scharringa, J; Van Dijk, K; Fluit, A C; Leverstein-Van Hall, M

    2013-11-01

    The adequate detection of carbapenemase-producing Enterobacteriaceae (CPE) is essential for adequate antibiotic therapy and for infection control purposes, especially in an outbreak setting. Selective agars play an important role in the detection of CPE. The Oxoid Brilliance™ CRE Agar (Thermo Fisher Scientific) was evaluated for the detection of CPE using 255 non-repetitive Enterobacteriaceae isolates, including 95 CPE (36 KPC, 4 KPC plus VIM, 4 NDM, 6 GIM, 20 VIM, and 25 OXA-48-producing isolates). The sensitivity of the CRE agar for the detection of CPE was 94 % (89/95), but differed per carbapenemase gene (100 % for KPC, NDM, and GIM, 90 % for VIM, and 84 % for OXA-48-producing isolates). The specificity of the CRE agar was 71 %, due to the growth of AmpC- and/or ESBL-producing isolates. The CRE agar is a sensitive tool for the detection of KPC and metallo-carbapenemase-producing Enterobacteriaceae, although the detection of OXA-48 producers is less optimal. The relatively low specificity requires confirmation of carbapenemase production for isolates recovered from the CRE agar.

  3. Entrapment of α-Amylase in Agar Beads for Biocatalysis of Macromolecular Substrate

    PubMed Central

    Sharma, Manu; Sharma, Vinay; Majumdar, Dipak K.

    2014-01-01

    Attempts have been made to optimize immobilization parameters, catalytic property, and stability of immobilized α-amylase in agar. The work compares natural entrapment efficiency of agar with the ionotropically cross-linked agar hydrogel, with the advantage of easy scale-up and cost and time effectiveness. Beads prepared with 3% (w/v) agar and 75 mM calcium chloride and hardened for 20 minutes were selected for further studies on the basis of entrapment efficiency (80%) and physical stability. Following entrapment, pH and temperature optima of enzyme were shifted from 6 to 6.5 and 50 to 55°C, respectively. Michaelis constant (Km) for both free and entrapped enzymes remained the same (0.83%) suggesting no change in substrate affinity. However, Vmax⁡ of entrapped enzyme decreased ~37.5-fold. The midpoint of thermal inactivation for entrapped enzyme increased by 8 ± 1°C implying its higher thermal stability. The entrapped enzyme in calcium agar bead had an Ea value of 27.49 kcal/mol compared to 17.6 kcal/mol for free enzyme indicating increased stability on entrapment. Half-life of enzyme increased ~2.2 times after entrapment in calcium agar at 60°C indicating stabilization of enzyme. The reusability of beads was size dependent. Beads with diameter <710 μm were stable and could be reused for 6 cycles with ~22% loss in activity. PMID:27382608

  4. Complex impedance and conductivity of agar-based ion-conducting polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Nwanya, A. C.; Amaechi, C. I.; Udounwa, A. E.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

    2015-04-01

    Agar-based electrolyte standing films with different salts and weak acids as ion and proton conductors were prepared and characterized by X-ray diffraction, UV-visible spectrophotometry, photoluminescence emission spectroscopy and electrochemical impedance spectroscopy. The salts used are lithium perchlorate (LiClO4) and potassium perchlorate (KClO4), while the weak acids used are acetic acid (CH3COOH) and lactic acid (C3H6O3). The values of the ion conductivity obtained for the agar-based polymer films are 6.54 × 10-8, 9.12 × 10-8, 3.53 × 10-8, 2.24 × 10-8 S/cm for the agar/acetic acid, agar/lactic acid, agar/LiClO4 and agar/KClO4 polymer films, respectively. As a function of temperature, the ion conductivity exhibits an Arrhenius behavior and the estimated activation energy is ≈0.1 eV for all the samples. The samples depicted high values of dielectric permittivity toward low frequencies which is due mostly to electrode polarization effect. The samples showed very high transparency (85-98 %) in the visible region, and this high transparency is one of the major requirements for application in electrochromic devices (ECD). The values of conductivity and activation energy obtained indicate that the electrolytes are good materials for application in ECD.

  5. [GROWTH OF MICROMYCETES FROM DIFFERENT ECOLOGICAL NICHES ON AGAR NUTRIENT MEDIA].

    PubMed

    Kurchenko, I M; Yurieva, E M; Voychuk, S I

    2015-01-01

    Radial growth rate of (K(r)) 153 strains 6 species of micromycetes from different ecological niches was studied on 7 agar media: three standard (malt extract agar, potato-dextrose agar, Czapek's agar), and on agar media with plant polymers (carboxymethylcellulose, xylan, soluble starch and apple pectin). Endophytic and plant pathogenic strains (biotrophs) of all studied species did not differ significantly in their ability to grow on nutrient media of different composition--average values of K(r) for these two groups were the same (0,200 and 0,199 mm/h, respectively). Soil micromycetes (saprophytes) characterized by the lowest average growth rate (0,169 mm/h) and significantly differed from the endophytic and plant pathogenic ones. Average of the radial growth rates of studied microscopic fungi were higher on standard nutrient media than with plant polymers ones. Growth parameters of endophytes and plant pathogens of all studied species on various agar media differed from the soil strains. High growth rate of endophytic and plant pathogenic strains of Fusarium poae, Alternaria alternata and Ceratocystis sp. provides them the rapid colonization of plants. Penicillium funiculosum strains equally can exist as saprophytes in soil and as endophytic plant symbionts. A wide range of K(r) variation of endophytic dark pigmented Mycelia sterilia indicates the presence in this group of different species of micromycetes, which have no sporulation.

  6. Broth versus solid agar culture of swab samples of cadaveric allograft musculoskeletal tissue.

    PubMed

    Varettas, Kerry

    2013-12-01

    As part of the donor assessment protocol, bioburden assessment must be performed on allograft musculoskeletal tissue samples collected at the time of tissue retrieval. Swab samples of musculoskeletal tissue allografts from cadaveric donors are received at the microbiology department of the South Eastern Area Laboratory Services (Australia) to determine the presence of bacteria and fungi. This study will review the isolation rate of organisms from solid agar and broth culture of swab samples of cadaveric allograft musculoskeletal tissue over a 6-year period, 2006-2011. Swabs were inoculated onto horse blood agar (anaerobic, 35 °C) and chocolate agar (CO2, 35 °C) and then placed into a cooked meat broth (aerobic, 35 °C). A total of 1,912 swabs from 389 donors were received during the study period. 557 (29.1 %) swabs were culture positive with the isolation of 713 organisms, 249 (34.9 %) from solid agar culture and an additional 464 (65.1 %) from broth culture only. This study has shown that the broth culture of cadaveric allograft musculoskeletal swab samples recovered a greater amount of organisms than solid agar culture. Isolates such as Clostridium species and Staphylococcus aureus would not have been isolated from solid agar culture alone. Broth culture is an essential part of the bioburden assessment protocol of swab samples of cadaveric allograft musculoskeletal tissue in this laboratory.

  7. Susceptibilities of Mycobacterium tuberculosis to isoniazid and rifampin on blood agar.

    PubMed

    Coban, Ahmet Yilmaz; Bilgin, Kemal; Uzun, Meltem; Tasdelen Fisgin, Nuriye; Akgunes, Alper; Cihan, Cigdem Cekic; Birinci, Asuman; Durupinar, Belma

    2005-04-01

    In this study, blood agar was used instead of 7H10 agar for the susceptibility testing of 34 clinical isolates of Mycobacterium tuberculosis to isoniazid (INH) and rifampin (RIF) in accordance with the NCCLS. The BACTEC 460 TB system (Becton Dickinson, Sparks, Md.) was used as a "gold standard." Results for both media were in agreement for RIF and INH at 100 and 94.1%, respectively. For INH, the specificity, sensitivity, positive predictive value, and negative predictive value were found to be 71.4, 100, 93.1, and 100%, respectively, while these values were 100% for RIF. In addition, the results of the susceptibility test performed with blood agar were obtained on day 14 of incubation. In conclusion, results were obtained much earlier with blood agar (2 weeks) than with 7H10 agar (3 weeks), and the results of this study suggest that blood agar may be used as an alternative medium for the susceptibility testing of M. tuberculosis to INH and RIF.

  8. Ratio, Proportion and Scaling. Mathematics Resource Project.

    ERIC Educational Resources Information Center

    Hoffer, Shirley Ann, Ed.

    The Mathematics Resource Project has as its goal the production of topical resources for teachers, drawn from the vast amounts of available material. This experimental edition on Ratio, Proportion, and Scaling, contains a teaching emphasis section, a classroom materials section, and teacher commentaries. The teaching emphasis section stresses…

  9. Augmented mixed models for clustered proportion data

    PubMed Central

    Bandyopadhyay, Dipankar; Galvis, Diana M; Lachos, Victor H

    2015-01-01

    Often in biomedical research, we deal with continuous (clustered) proportion responses ranging between zero and one quantifying the disease status of the cluster units. Interestingly, the study population might also consist of relatively disease-free as well as highly diseased subjects, contributing to proportion values in the interval [0, 1]. Regression on a variety of parametric densities with support lying in (0, 1), such as beta regression, can assess important covariate effects. However, they are deemed inappropriate due to the presence of zeros and/or ones. To evade this, we introduce a class of general proportion density, and further augment the probabilities of zero and one to this general proportion density, controlling for the clustering. Our approach is Bayesian and presents a computationally convenient framework amenable to available freeware. Bayesian case-deletion influence diagnostics based on q-divergence measures are automatic from the Markov chain Monte Carlo output. The methodology is illustrated using both simulation studies and application to a real dataset from a clinical periodontology study. PMID:25491718

  10. Golden Proportions for the Generalized Tribonacci Numbers

    ERIC Educational Resources Information Center

    Shah, Devbhadra V.; Mehta, Darshana A.

    2009-01-01

    It is known that the ratios of consecutive terms of Fibonacci and Tribonacci sequences converge to the fixed ratio. In this article, we consider the generalized form of Tribonacci numbers and derive the "golden proportion" for the whole family of this generalized sequence. (Contains 2 tables.)

  11. Indices of body proportionality in neonates.

    PubMed

    Tsou Yau, K I; Chang, M H

    1993-01-01

    The inadequacy of using body weight alone to evaluate fetal skeletal and soft-tissue growth has long been recognized. Body proportionality indices could identify symptomatic newborn infants better than size-for-date classification. Lack of normative data precludes its being used, practically, in Chinese newborns. Thus body weight, body length, head circumference and mid-arm circumference were measured in 240 neonates appropriate for gestational age, 27-42 weeks, 960-3918 g, to construct reference indices of body proportionality: ponderal index (PI), body mass index (BMI), weight/length ratio (W/L), head circumference/body length ratio (HC/L) and mid-arm circumference/head circumference ratio (MAC/HC). All the five indices of body proportionality but HC/L were statistically correlated with gestational age (GA). For full-term newborns, PI did not correlate with GA. Furthers, the MAC/HC ratio decreased after 40 weeks' gestation. Therefore, when these indices of body proportionality are used to evaluate intrauterine nutritional status of a newborn, the appropriate standard for GA should be considered. PMID:8372678

  12. Canine Conjectures: Using Data for Proportional Reasoning

    ERIC Educational Resources Information Center

    Westenskow, Arla; Moyer-Packenham, Patricia S.

    2011-01-01

    No person, place, or thing can capture the attention of a class of sixth graders like "man's best friend." To prompt students' interest in a series of lessons on proportional relationships, the authors brought in a unique teaching aid--a dog. A family dog was used to supply the measurements for scatter plots and variables so that students could…

  13. Kitchen Gardens: Contexts for Developing Proportional Reasoning

    ERIC Educational Resources Information Center

    Hilton, Annette; Hilton, Geoff; Dole, Shelley; Goos, Merrilyn; O'Brien, Mia

    2013-01-01

    It is great to see how the sharing of ideas sparks new ideas. In 2011 Lyon and Bragg wrote an "Australian Primary Mathematics Classroom" (APMC) article on the mathematics of kitchen gardens. In this article the authors show how the kitchen garden may be used as a starting point for proportional reasoning. The authors highlight different…

  14. Optimization of modified Middlebrook 7H11 agar for isolation of Mycobacterium bovis from raw milk cheese.

    PubMed

    Forgrave, R; Donaghy, J A; Fisher, A; Rowe, M T

    2014-10-01

    Reports have highlighted the absence of contemporary peer reviewed publications pertaining to Mycobacterium bovis culture from raw milk and cheese. By replicating traditional methods, cheese-making methodology and equipment were devised to produce Cheddar (n = 6) and Caerphilly (n = 3) artificially contaminated with M. bovis (three genotypes) under stringent laboratory-containment guidelines for handling hazardous microbiological material. Middlebrook 7H11, modified for M. bovis isolation, was assessed for capacity to enumerate M. bovis despite changing cheese microflora and prolonged M. bovis exposure to the cheese matrix using maturing cheese test portions (n = 63; up to 16 weeks). Malachite green (MG) containing media isolated M. bovis at significantly (P < 0·05) lower levels than unmodified Middlebrook 7H11 agar despite MG being a common adjunct of Middlebrook 7H11 agar modified for M. bovis growth. Subsequently, a selective MG-free Middlebrook 7H11 agar modified using haemolysed red cells and calf serum was demonstrated as the best performing (P < 0·05) medium for recovery of M. bovis from typical UK cheese types, Cheddar and Caerphilly. Significance and impact of the study: Following increased M. bovis infection of UK cattle, the risk posed to consumers from consumption of unpasteurized milk and dairy products has changed. Furthermore, published methods for the culture and molecular detection of M. bovis in raw milk products are limited. Cheese-making protocols and M. bovis culture media reported here provide tools for further investigation of M. bovis survival during all stages of cheese manufacture and could inform future assessment of the risk to consumers from M. bovis contamination of unpasteurized dairy products.

  15. Optimization of modified Middlebrook 7H11 agar for isolation of Mycobacterium bovis from raw milk cheese.

    PubMed

    Forgrave, R; Donaghy, J A; Fisher, A; Rowe, M T

    2014-10-01

    Reports have highlighted the absence of contemporary peer reviewed publications pertaining to Mycobacterium bovis culture from raw milk and cheese. By replicating traditional methods, cheese-making methodology and equipment were devised to produce Cheddar (n = 6) and Caerphilly (n = 3) artificially contaminated with M. bovis (three genotypes) under stringent laboratory-containment guidelines for handling hazardous microbiological material. Middlebrook 7H11, modified for M. bovis isolation, was assessed for capacity to enumerate M. bovis despite changing cheese microflora and prolonged M. bovis exposure to the cheese matrix using maturing cheese test portions (n = 63; up to 16 weeks). Malachite green (MG) containing media isolated M. bovis at significantly (P < 0·05) lower levels than unmodified Middlebrook 7H11 agar despite MG being a common adjunct of Middlebrook 7H11 agar modified for M. bovis growth. Subsequently, a selective MG-free Middlebrook 7H11 agar modified using haemolysed red cells and calf serum was demonstrated as the best performing (P < 0·05) medium for recovery of M. bovis from typical UK cheese types, Cheddar and Caerphilly. Significance and impact of the study: Following increased M. bovis infection of UK cattle, the risk posed to consumers from consumption of unpasteurized milk and dairy products has changed. Furthermore, published methods for the culture and molecular detection of M. bovis in raw milk products are limited. Cheese-making protocols and M. bovis culture media reported here provide tools for further investigation of M. bovis survival during all stages of cheese manufacture and could inform future assessment of the risk to consumers from M. bovis contamination of unpasteurized dairy products. PMID:24888395

  16. Intermediate Moral Respect and Proportionality Reasoning.

    PubMed

    Finegan, Thomas

    2016-10-01

    In a recent article in this journal Jonathan Pugh critiques the idea of intermediate 'moral respect' which some say is owed to embryos. This concept is inherent within the 'principle of proportionality', the principle that destructive research on embryos is permissable only if the research serves an important purpose. Pugh poses two specific questions to proponents of the idea of intermediate moral respect. This article argues that while the questions posed by Pugh are certainly pertinent to the debate, the hypothetical responses he suggests to these questions do not quite get to the core of what is troublesome about the concept. The article suggests alternative responses to Pugh's questions in order to focus attention on more fundamental problems facing the idea of intermediate moral respect, while also pointing to how the intermediate moral respect proponent might best develop these responses. It goes on to argue that these hypothetical responses fail to answer convincingly the questions posed. More specifically, this article challenges two possible justifications for the distinct idea of intermediate moral respect, namely the argument from potentiality (the argument raised by Pugh) and an argument from the proportionality of fundamental moral status (not considered by Pugh). The article also raises a dilemma inherent in the application of the principle of proportionality to cases involving beings to which intermediate moral respect is owed even where it is allowed, ex hypothesi, that both the category of intermediate moral respect and the general proportionality reasoning underpinning the principle of proportionality are basically cogent. This article thus develops and adds to the challenge laid down by Pugh to proponents of the idea of intermediate moral respect. PMID:27212688

  17. Intermediate Moral Respect and Proportionality Reasoning.

    PubMed

    Finegan, Thomas

    2016-10-01

    In a recent article in this journal Jonathan Pugh critiques the idea of intermediate 'moral respect' which some say is owed to embryos. This concept is inherent within the 'principle of proportionality', the principle that destructive research on embryos is permissable only if the research serves an important purpose. Pugh poses two specific questions to proponents of the idea of intermediate moral respect. This article argues that while the questions posed by Pugh are certainly pertinent to the debate, the hypothetical responses he suggests to these questions do not quite get to the core of what is troublesome about the concept. The article suggests alternative responses to Pugh's questions in order to focus attention on more fundamental problems facing the idea of intermediate moral respect, while also pointing to how the intermediate moral respect proponent might best develop these responses. It goes on to argue that these hypothetical responses fail to answer convincingly the questions posed. More specifically, this article challenges two possible justifications for the distinct idea of intermediate moral respect, namely the argument from potentiality (the argument raised by Pugh) and an argument from the proportionality of fundamental moral status (not considered by Pugh). The article also raises a dilemma inherent in the application of the principle of proportionality to cases involving beings to which intermediate moral respect is owed even where it is allowed, ex hypothesi, that both the category of intermediate moral respect and the general proportionality reasoning underpinning the principle of proportionality are basically cogent. This article thus develops and adds to the challenge laid down by Pugh to proponents of the idea of intermediate moral respect.

  18. Preparation, Optimization, and Screening of the Effect of Processing Variables on Agar Nanospheres Loaded with Bupropion HCl by a D-Optimal Design.

    PubMed

    Varshosaz, Jaleh; Zaki, Mohammad Reza; Minaiyan, Mohsen; Banoozadeh, Jaafar

    2015-01-01

    Bupropion is an atypical antidepressant drug. Fluctuating in its serum levels following oral administration of immediate release dosage forms leads to occasional seizure. The aim of the present work was designing of sustained release bupropion HCl nanospheres suited for pulmonary delivery. Agar nanospheres were prepared by transferring the w/o emulsion to solid in oil (s/o) suspension. Calcium chloride was used as cross-linking agent and hydroxypropyl β-cyclodextrin (HPβCD) was used as permeability enhancer. A response surface D-optimal design was used for optimization of nanospheres. Independent factors included in the design were calcium chloride percent, speed of homogenization, agar percent, and HPβCD percent. Optimum condition was predicted to be achieved when the calcium chloride was set at 7.19%, homogenization speed at 8500 rpm, agar content at 2%, and HPβCD at 0.12%. The optimized nanoparticles showed particle size of 587 nm, zeta potential of -30.9 mV, drug loading efficiency of 38.6%, and release efficiency of 51% until 5 h. The nanospheres showed high degree of bioadhesiveness. D-optimal response surface method is a satisfactory design to optimize the fabrication of bupropion HCl loaded agar nanospheres and these nanospheres can be successively exploited to deliver bupropion in a controlled manner for a sufficiently extended period.

  19. Preparation, Optimization, and Screening of the Effect of Processing Variables on Agar Nanospheres Loaded with Bupropion HCl by a D-Optimal Design

    PubMed Central

    Varshosaz, Jaleh; Zaki, Mohammad Reza; Minaiyan, Mohsen; Banoozadeh, Jaafar

    2015-01-01

    Bupropion is an atypical antidepressant drug. Fluctuating in its serum levels following oral administration of immediate release dosage forms leads to occasional seizure. The aim of the present work was designing of sustained release bupropion HCl nanospheres suited for pulmonary delivery. Agar nanospheres were prepared by transferring the w/o emulsion to solid in oil (s/o) suspension. Calcium chloride was used as cross-linking agent and hydroxypropyl β-cyclodextrin (HPβCD) was used as permeability enhancer. A response surface D-optimal design was used for optimization of nanospheres. Independent factors included in the design were calcium chloride percent, speed of homogenization, agar percent, and HPβCD percent. Optimum condition was predicted to be achieved when the calcium chloride was set at 7.19%, homogenization speed at 8500 rpm, agar content at 2%, and HPβCD at 0.12%. The optimized nanoparticles showed particle size of 587 nm, zeta potential of −30.9 mV, drug loading efficiency of 38.6%, and release efficiency of 51% until 5 h. The nanospheres showed high degree of bioadhesiveness. D-optimal response surface method is a satisfactory design to optimize the fabrication of bupropion HCl loaded agar nanospheres and these nanospheres can be successively exploited to deliver bupropion in a controlled manner for a sufficiently extended period. PMID:26090423

  20. Proportion of hospital readmissions deemed avoidable: a systematic review

    PubMed Central

    van Walraven, Carl; Bennett, Carol; Jennings, Alison; Austin, Peter C.; Forster, Alan J.

    2011-01-01

    Background Readmissions to hospital are increasingly being used as an indicator of quality of care. However, this approach is valid only when we know what proportion of readmissions are avoidable. We conducted a systematic review of studies that measured the proportion of readmissions deemed avoidable. We examined how such readmissions were measured and estimated their prevalence. Methods We searched the MEDLINE and EMBASE databases to identify all studies published from 1966 to July 2010 that reviewed hospital readmissions and that specified how many were classified as avoidable. Results Our search strategy identified 34 studies. Three of the studies used combinations of administrative diagnostic codes to determine whether readmissions were avoidable. Criteria used in the remaining studies were subjective. Most of the studies were conducted at single teaching hospitals, did not consider information from the community or treating physicians, and used only one reviewer to decide whether readmissions were avoidable. The median proportion of readmissions deemed avoidable was 27.1% but varied from 5% to 79%. Three study-level factors (teaching status of hospital, whether all diagnoses or only some were considered, and length of follow-up) were significantly associated with the proportion of admissions deemed to be avoidable and explained some, but not all, of the heterogeneity between the studies. Interpretation All but three of the studies used subjective criteria to determine whether readmissions were avoidable. Study methods had notable deficits and varied extensively, as did the proportion of readmissions deemed avoidable. The true proportion of hospital readmissions that are potentially avoidable remains unclear. PMID:21444623

  1. Conventional and microwave pyrolysis of a macroalgae waste from the Agar-Agar industry. Prospects for bio-fuel production.

    PubMed

    Ferrera-Lorenzo, N; Fuente, E; Bermúdez, J M; Suárez-Ruiz, I; Ruiz, B

    2014-01-01

    A comparative study of the pyrolysis of a macroalgae industrial solid waste (algae meal) in an electrical conventional furnace and in a microwave furnace has been carried out. It was found that the chars obtained from both pyrolyses are similar and show good properties for performing as a solid bio-fuel and as a precursor of activated carbon. Bio-oils from conventional pyrolysis have a greater number of phenolic, pyrrole and alkane compounds whereas benzene and pyridine compounds are more predominant in microwave pyrolysis with a major presence of light compounds. The bio-gas fraction from microwave pyrolysis presents a much higher syngas content (H2+CO), and a lower CO2 and CH4 proportion than that obtained by conventional pyrolysis. Yields are similar for both treatments with a slightly higher gas yield in the case of microwave pyrolysis due to the fact that microwave heating favors heterogeneous reactions between the gases and the char.

  2. Maximum-likelihood estimation of admixture proportions from genetic data.

    PubMed Central

    Wang, Jinliang

    2003-01-01

    For an admixed population, an important question is how much genetic contribution comes from each parental population. Several methods have been developed to estimate such admixture proportions, using data on genetic markers sampled from parental and admixed populations. In this study, I propose a likelihood method to estimate jointly the admixture proportions, the genetic drift that occurred to the admixed population and each parental population during the period between the hybridization and sampling events, and the genetic drift in each ancestral population within the interval between their split and hybridization. The results from extensive simulations using various combinations of relevant parameter values show that in general much more accurate and precise estimates of admixture proportions are obtained from the likelihood method than from previous methods. The likelihood method also yields reasonable estimates of genetic drift that occurred to each population, which translate into relative effective sizes (N(e)) or absolute average N(e)'s if the times when the relevant events (such as population split, admixture, and sampling) occurred are known. The proposed likelihood method also has features such as relatively low computational requirement compared with previous ones, flexibility for admixture models, and marker types. In particular, it allows for missing data from a contributing parental population. The method is applied to a human data set and a wolflike canids data set, and the results obtained are discussed in comparison with those from other estimators and from previous studies. PMID:12807794

  3. A comparison of the performance of commercially available chromogenic agars for the isolation and presumptive identification of organisms from urine

    PubMed Central

    Fallon, D; Ackland, G; Andrews, N; Frodsham, D; Howe, S; Howells, K; Nye, K J; Warren, R E

    2003-01-01

    Aims: To compare four media—UTI medium, BBL CHROMagar, CPS ID2, and Harlequin CLED—using a collection of fully characterised organisms and subsequent “field trial”. Methods: Seven hundred and eighty seven fully characterised isolates (730 Gram negative bacteria, 47 Gram positive bacteria, and 10 yeasts) were used to test for accuracy of organism identification. To assess isolation rates and ability to detect mixed cultures, 1435 urine samples were cultured in the three best performing chromogenic media (UTI medium, BBL CHROMagar, and CPS ID2) and CLED. Results: The chromogenic agars differed in their accuracy of identification, with BBL CHROMagar performing best and Harlequin CLED performing least well. Similarly, BBL CHROMagar achieved a higher overall isolation rate than UTI medium and CPS ID2. When mixed growth was defined as greater than two organism types, BBL CHROMagar detected more mixed cultures than did UTI medium and CPS ID2, although the differences were not significant. When mixed growth was defined as greater than one organism type the increased number of mixed growths detected by BBL CHROMagar became significant, largely because of differences in enterococcal isolation rates. Conclusion: The use of BBL CHROMagar, UTI medium, or CPS ID2 chromogenic agar as a replacement for CLED agar would improve the detection rate of contaminated urine samples. Enhanced identification helps to distinguish different species, facilitating the monitoring of bacterial resistance in support of the national antibiotic strategy. BBL CHROMagar gave the highest overall organism recovery rates, greatest ability to detect mixed cultures, and the most accurate identification of organisms. PMID:12890812

  4. Proportional Reasoning of Preservice Elementary Education Majors: An Epistemic Model of the Proportional Reasoning Construct.

    ERIC Educational Resources Information Center

    Fleener, M. Jayne

    Current research and learning theory suggest that a hierarchy of proportional reasoning exists that can be tested. Using G. Vergnaud's four complexity variables (structure, content, numerical characteristics, and presentation) and T. E. Kieren's model of rational number knowledge building, an epistemic model of proportional reasoning was…

  5. Antimicrobial susceptibility testing for Helicobacter pylori isolates from Brazilian children and adolescents: Comparing agar dilution, E-test, and disk diffusion

    PubMed Central

    Ogata, Silvio Kazuo; Gales, Ana Cristina; Kawakami, Elisabete

    2014-01-01

    Antimicrobial susceptibility testing for Helicobacter pylori is increasingly important due to resistance to the most used antimicrobials agents. Only agar dilution method is approved by CLSI, but it is difficult to perform routinely. We evaluated the reliability of E-test and disk diffusion comparing to agar dilution method on Helicobacter pylori antimicrobial susceptibility testing. Susceptibility testing was performed for amoxicillin, clarithromycin, furazolidone, metronidazole and tetracycline using E-test, disk-diffusion and agar dilution method in 77 consecutive Helicobacter pylori strains from dyspeptic children and adolescents. Resistance rates were: amoxicillin - 10.4%, 9% and 68.8%; clarithromycin - 19.5%, 20.8%, 36.3%; metronidazole - 40.2%33.7%, 38.9%, respectively by agar dilution, E-test and disk diffusion method. Furazolidone and tetracycline showed no resistance rates. Metronidazole presented strong correlation to E-test (r = 0.7992, p < 0.0001) and disk diffusion method (r=-0.6962, p < 0.0001). Clarithromycin presented moderate correlation to E-test (r = 0.6369, p < 0.0001) and disk diffusion method (r=−0.5656, p < 0.0001). Amoxicillin presented weak correlation to E-test (r = 0.3565, p = 0.0015) and disk diffusion (r=−0.3565, p = 0.0015). Tetracycline presented weak correlation with E-test (r = 0.2346, p = 0.04) and furazolidone to disk diffusion (r=−0.0288, p = 0.8038). E-test presented better agreement with gold standard. It is an easy and reliable method for Helicobacter pylori susceptibility testing. Disk diffusion method presented high disagreement and high rates of major errors. PMID:25763052

  6. Processing of Numerical and Proportional Quantifiers.

    PubMed

    Shikhare, Sailee; Heim, Stefan; Klein, Elise; Huber, Stefan; Willmes, Klaus

    2015-09-01

    Quantifier expressions like "many" and "at least" are part of a rich repository of words in language representing magnitude information. The role of numerical processing in comprehending quantifiers was studied in a semantic truth value judgment task, asking adults to quickly verify sentences about visual displays using numerical (at least seven, at least thirteen, at most seven, at most thirteen) or proportional (many, few) quantifiers. The visual displays were composed of systematically varied proportions of yellow and blue circles. The results demonstrated that numerical estimation and numerical reference information are fundamental in encoding the meaning of quantifiers in terms of response times and acceptability judgments. However, a difference emerges in the comparison strategies when a fixed external reference numerosity (seven or thirteen) is used for numerical quantifiers, whereas an internal numerical criterion is invoked for proportional quantifiers. Moreover, for both quantifier types, quantifier semantics and its polarity (positive vs. negative) biased the response direction (accept/reject). Overall, our results indicate that quantifier comprehension involves core numerical and lexical semantic properties, demonstrating integrated processing of language and numbers. PMID:25631283

  7. NASA CONNECT: Proportionality: Modeling the Future

    NASA Technical Reports Server (NTRS)

    2000-01-01

    'Proportionality: Modeling the Future' is the sixth of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov 'Proportionality: Modeling the Future', students will examine how patterns, measurement, ratios, and proportions are used in the research, development, and production of airplanes.

  8. Evaluation of Facial Beauty Using Anthropometric Proportions

    PubMed Central

    Milutinovic, Jovana

    2014-01-01

    The improvement of a patient's facial appearance is one of the main goals of contemporary orthodontic treatment. The aim of this investigation was to evaluate the difference in facial proportions between attractive and anonymous females in order to establish objective facial features which are widely considered as beautiful. The study included two groups: first group consisted of 83 Caucasian female subjects between 22 and 28 years of age who were selected from the population of students at the University of Belgrade, and the second group included 24 attractive celebrity Caucasian females. The en face facial photographs were taken in natural head position (NHP). Numerous parameters were recorded on these photographs, in order to establish facial symmetry and correlation with the ideal set of proportions. This study showed significant difference between anonymous and attractive females. Attractive females showed smaller face in general and uniformity of the facial thirds and fifths, and most of the facial parameters meet the criteria of the ideal proportions. PMID:24701166

  9. The PEP Quark Search Proportional Chambers

    NASA Astrophysics Data System (ADS)

    Parker, S. I.; Harris, F.; Karliner, I.; Yount, D.; Ely, R.; Hamilton, R.; Pun, T.; Guryn, W.; Miller, D.; Fries, R.

    1981-04-01

    Proportional chambers are used in the PEP Free Quark Search to identify and remove possible background sources such as particles traversing the edges of counters, to permit geometric corrections to the dE/dx and TOF information from the scintillator and Cerenkov counters, and to look for possible high cross section quarks. The present beam pipe has a thickness of 0.007 interaction lengths (λi) and is followed in both arms (each with 45° <= θ <= 135°. Δphi = 90°) by 5 proportional chambers, each 0.0008 λi thick with 32 channels of pulse height readout, and by 3 thin scintillator planes, each 0.003 λi thick. Following this thin front end, each arm of the detector has 8 layers of scintillator (one with scintillating light pipes) interspersed with 4 proportional chambers and a layer of lucite Cerenkov counters. Both the calculated ion statistics and measurements using He-CH4 gas in a test chamber indicate that the chamber efficiencies should be > 98% for q = 1/3. The Landau spread measured in the test was equal to that observed for normal q = 1 traversals. One scintillator plane and thin chamber in each arm will have an extra set of ADC's with a wide gate bracketing the normal one so timing errors and tails of earlier pulses should not produce fake quarks.

  10. The use of polycarbonate in proportional counters

    SciTech Connect

    Trow, M.; Smith, A. )

    1992-01-01

    Proportional counters are relatively sensitive to contamination through outgassing and the range of electrical insulators suitable for use in their manufacture is quite limited. Although small amounts of plastics such as polychlorotrifluoroethylene have been used as feedthroughs, ceramics are most commonly used when sealed counters with long lives are required. Ceramics have poor and widely scattered mechanical properties and the use of a more robust material is often highly desirable. Of particular interest is the use of polymers and this work examines polycarbonate in particular. To investigate its suitability in terms of outgassing a simple cylindrical, single anode proportional counter containing a large sample of polycarbonate was baked at {similar to}100 {degree}C and filled with a CO{sub 2}/Ar/Xe mixture (5:47.5:47.5 by pressure, respectively). Subsequent measurements of the counter indicated an increase in gain, which, after a second similar filling, was identified to be associated with a preferential loss of CO{sub 2} to the polycarbonate. The consequences of this result and the circumstances under which polycarbonate could be used on a large scale in the construction of proportional counters are discussed.

  11. Determination of in vitro synergy for dual antimicrobial therapy against resistant Neisseria gonorrhoeae using Etest and agar dilution.

    PubMed

    Wind, Carolien M; de Vries, Henry J C; van Dam, Alje P

    2015-03-01

    In response to antimicrobial resistance of Neisseria gonorrhoeae to last-resort extended-spectrum cephalosporins, combination therapy of azithromycin+ceftriaxone is now recommended. Dual therapy can be effective to treat monoresistant strains as well as multidrug-resistant strains, preferably employing the effect of in vitro synergy. As reports on in vitro synergy of azithromycin+ceftriaxone in N. gonorrhoeae are conflicting, in this study an evaluation of this combination was performed using a cross-wise Etest method and agar dilution. Synergy was defined as a fractional inhibitory concentration index (FICI) of ≤0.5. To identify other dual treatment options for gonorrhoea, in vitro synergy was evaluated for 65 dual antimicrobial combinations using Etest. Azithromycin, cefixime, ceftriaxone, colistin, ertapenem, fosfomycin, gentamicin, minocycline, moxifloxacin, rifampicin, spectinomycin and tigecycline were screened for synergy in all possible combinations. No synergy or antagonism was found for any of the 65 combinations. The geometric mean FICI ranged from 0.82 to 2.00. The mean FICI of azithromycin+ceftriaxone was 1.18 (Etest) and 0.55 (agar dilution). The difference between both methods did not result in a difference in interpretation of synergy. Ceftriaxone-resistant strain F89 was tested in all combinations and no synergy was found for any of them. Most importantly, the ceftriaxone minimum inhibitory concentration of F89 was not decreased below the breakpoint with any concentration of azithromycin.

  12. Injection of Acanthaster planci with thiosulfate-citrate-bile-sucrose agar (TCBS). II. Histopathological changes.

    PubMed

    Rivera-Posada, J A; Pratchett, M; Owens, L

    2011-12-01

    We assessed histological changes in the tissues of the crown-of-thorns starfish Acanthaster planci (COTS) after injection of thiosulfate-citrate-bile-sucrose agar (TCBS) which was used as a disease inducer (potential outbreak control method), by conventional and scanning electron microscopy. Digestive glands were processed and stained with hematoxylin and eosin to describe the histological architecture of the intestinal epithelium. Subsequently comparison of healthy versus infected tissues and Gram stains were carried out to confirm bacterial occurrence on infected tissues, characterize the structural changes induced by bacterial communities in COTS tissues, and to determine if the histopathological changes of intestinal tissues were consistent with vibrio infection. TCBS injections induced marked epithelial desquamation, hypertrophy and hypersecretion of glandular cells, epithelial cell destruction, pyknosis, reduction of thickness and disorganization of connective tissue and associated nerve plexus, presence of bacterial colonies, irregular eosinophilic foci in glandular cells, brush border disruption, atrophy and detachment of intestinal microvilli and cell debris in the lumen. All these changes were attributed to a fulminating systemic dysbiosis and were consistent with vibrio infections.

  13. Development and validation of a microbiological agar assay for determination of orbifloxacin in pharmaceutical preparations.

    PubMed

    Cazedey, Edith C L; Salgado, Hérida R N

    2011-01-01

    Orbifloxacin is a fluoroquinolone with broad-spectrum antimicrobial activity, and belongs to the third generation of quinolones. Regarding the quality control of medicines, a validated microbiological assay for determination of orbifloxacin in pharmaceutical formulations has not as yet been reported. For this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify orbifloxacin in tablet formulations. The assay is based on the inhibitory effect of orbifloxacin upon the strain of Staphylococcus aureus ATCC 25923 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.9992) in the selected range of 16.0-64.0 μg/mL, precise with relative standard deviation (RSD) of repeatability intraday = 2.88%, intermediate precision RSD = 3.33%, and accurate (100.31%). The results demonstrated the validity of the proposed bioassay, which allows reliable orbifloxacin quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.

  14. Development and Validation of a Microbiological Agar Assay for Determination of Orbifloxacin in Pharmaceutical Preparation

    PubMed Central

    Cazedey, Edith C. L.; Salgado, Hérida R. N.

    2011-01-01

    Orbifloxacin is a fluoroquinolone with broad-spectrum antimicrobial activity, and belongs to the third generation of quinolones. Regarding the quality control of medicines, a validated microbiological assay for determination of orbifloxacin in pharmaceutical formulations has not as yet been reported. For this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify orbifloxacin in tablet formulations. The assay is based on the inhibitory effect of orbifloxacin upon the strain of Staphylococcus aureus ATCC 25923 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.9992) in the selected range of 16.0–64.0 μg/mL, precise with relative standard deviation (RSD) of repeatability intraday = 2.88%, intermediate precision RSD = 3.33%, and accurate (100.31%). The results demonstrated the validity of the proposed bioassay, which allows reliable orbifloxacin quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine. PMID:24310597

  15. Tetrazolium reduction as an aid for streptococcal growth detection with agar dilution susceptibility testing.

    PubMed Central

    Coudron, P E; Ford, J M; Dalton, H P

    1983-01-01

    A dye reduction method for determining a definitive endpoint with agar dilution susceptibility testing has been developed. Bacterial growth was determined by applying to the inoculum spot a dye solution containing 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride and phenazine methosulfate. Viable colonies reduced the tetrazolium salt to a visible red color within 3 to 5 min. The minimum inhibitory concentrations of six antimicrobial agents tested against 167 clinical streptococcal isolates were recorded before and after the addition of the tetrazolium-phenazine methosulfate solution. A total of 252 discrepancies (25%) were observed, and of these, 30 (12%) differed by more than one tested antibiotic concentration. Endpoint reproducibility of the dye procedure was assessed by four technologists in a double-blind study. A 2.7-fold reduction in disagreement was observed when the dye was used. Use of the tetrazolium-phenazine methosulfate solution involves little deviation from standard antimicrobial susceptibility test procedures and yields more accurate, as well as reproducible, susceptibility results. PMID:6630459

  16. Synthesis and characterization of high-surface-area millimeter-sized silica beads with hierarchical multi-modal pore structure by the addition of agar

    SciTech Connect

    Han, Yosep; Choi, Junhyun; Tong, Meiping; Kim, Hyunjung

    2014-04-01

    Millimeter-sized spherical silica foams (SSFs) with hierarchical multi-modal pore structure featuring high specific surface area and ordered mesoporous frameworks were successfully prepared using aqueous agar addition, foaming and drop-in-oil processes. The pore-related properties of the prepared spherical silica (SSs) and SSFs were systematically characterized by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), Hg intrusion porosimetry, and N{sub 2} adsorption–desorption isotherm measurements. Improvements in the BET surface area and total pore volume were observed at 504 m{sup 2} g{sup −1} and 5.45 cm{sup 3} g{sup −1}, respectively, after an agar addition and foaming process. Despite the increase in the BET surface area, the mesopore wall thickness and the pore size of the mesopores generated from the block copolymer with agar addition were unchanged based on the SAXRD, TEM, and BJH methods. The SSFs prepared in the present study were confirmed to have improved BET surface area and micropore volume through the agar loading, and to exhibit interconnected 3-dimensional network macropore structure leading to the enhancement of total porosity and BET surface area via the foaming process. - Highlights: • Millimeter-sized spherical silica foams (SSFs) are successfully prepared. • SSFs exhibit high BET surface area and ordered hierarchical pore structure. • Agar addition improves BET surface area and micropore volume of SSFs. • Foaming process generates interconnected 3-D network macropore structure of SSFs.

  17. Collaborative investigation of broth microdilution and semisolid agar dilution for in vitro susceptibility testing of Candida albicans.

    PubMed

    Shawar, R; Paetznick, V; Witte, Z; Ensign, L G; Anaissie, E; LaRocco, M

    1992-08-01

    A study was performed in two laboratories to evaluate the effect of growth medium and test methodology on inter- and intralaboratory variations in the MICs of amphotericin B (AMB), flucytosine (5FC), fluconazole (FLU), itraconazole (ITRA), and the triazole Sch 39304 (SCH) against 14 isolates of Candida albicans. Testing was performed by broth microdilution and semisolid agar dilution with the following media, buffered to pH 7.0 with morpholinepropanesulfonic acid (MOPS): buffered yeast nitrogen base (BYNB), Eagle's minimal essential medium (EMEM), RPMI 1640 medium (RPMI), and synthetic amino acid medium for fungi (SAAMF). Inocula were standardized spectrophotometrically, and endpoints were defined by the complete absence of growth for AMB and by no more than 25% of the growth in the drug-free control for all other agents. Comparative analyses of median MICs, as determined by each test method, were made for all drug-medium combinations. Both methods yielded similar (+/- 1 twofold dilution) median MICs for AMB in EMEM and RPMI, 5FC in all media, and FLU in EMEM, RPMI, and SAAMF. In contrast, substantial between-method variations in median MICs were seen for AMB in BYNB and SAAMF, FLU In BYNB, and ITRA and SCH in all media. Interlaboratory concordance of median MICs was good for AMB, 5FC, and FLU but poor for ITRA and SCH in all media. Endpoint determinations were analyzed by use of kappa statistical analyses for evaluating the strength of observer agreement. Moderate to almost perfect interlaboratory agreement occurred with AMB and 5FC in all media and with FLU in EMEM, RPMI, and SAAMF, irrespective of the test method. Slight to almost perfect interlaboratory agreement occurred with ITRA and SCH in EMEM, RPMI, and SAAMF when tested by semisolid agar dilution but not broth microdilution. Kappa values assessing intralaboratory agreement between methods were high for 5FC in all media, for AMB in BYNB, ENEM, and RPMI, and for FLU in EMEM, RPMI, and SAAMF. One laboratory

  18. Collaborative investigation of broth microdilution and semisolid agar dilution for in vitro susceptibility testing of Candida albicans.

    PubMed Central

    Shawar, R; Paetznick, V; Witte, Z; Ensign, L G; Anaissie, E; LaRocco, M

    1992-01-01

    A study was performed in two laboratories to evaluate the effect of growth medium and test methodology on inter- and intralaboratory variations in the MICs of amphotericin B (AMB), flucytosine (5FC), fluconazole (FLU), itraconazole (ITRA), and the triazole Sch 39304 (SCH) against 14 isolates of Candida albicans. Testing was performed by broth microdilution and semisolid agar dilution with the following media, buffered to pH 7.0 with morpholinepropanesulfonic acid (MOPS): buffered yeast nitrogen base (BYNB), Eagle's minimal essential medium (EMEM), RPMI 1640 medium (RPMI), and synthetic amino acid medium for fungi (SAAMF). Inocula were standardized spectrophotometrically, and endpoints were defined by the complete absence of growth for AMB and by no more than 25% of the growth in the drug-free control for all other agents. Comparative analyses of median MICs, as determined by each test method, were made for all drug-medium combinations. Both methods yielded similar (+/- 1 twofold dilution) median MICs for AMB in EMEM and RPMI, 5FC in all media, and FLU in EMEM, RPMI, and SAAMF. In contrast, substantial between-method variations in median MICs were seen for AMB in BYNB and SAAMF, FLU In BYNB, and ITRA and SCH in all media. Interlaboratory concordance of median MICs was good for AMB, 5FC, and FLU but poor for ITRA and SCH in all media. Endpoint determinations were analyzed by use of kappa statistical analyses for evaluating the strength of observer agreement. Moderate to almost perfect interlaboratory agreement occurred with AMB and 5FC in all media and with FLU in EMEM, RPMI, and SAAMF, irrespective of the test method. Slight to almost perfect interlaboratory agreement occurred with ITRA and SCH in EMEM, RPMI, and SAAMF when tested by semisolid agar dilution but not broth microdilution. Kappa values assessing intralaboratory agreement between methods were high for 5FC in all media, for AMB in BYNB, ENEM, and RPMI, and for FLU in EMEM, RPMI, and SAAMF. One laboratory

  19. Collaborative investigation of broth microdilution and semisolid agar dilution for in vitro susceptibility testing of Candida albicans.

    PubMed

    Shawar, R; Paetznick, V; Witte, Z; Ensign, L G; Anaissie, E; LaRocco, M

    1992-08-01

    A study was performed in two laboratories to evaluate the effect of growth medium and test methodology on inter- and intralaboratory variations in the MICs of amphotericin B (AMB), flucytosine (5FC), fluconazole (FLU), itraconazole (ITRA), and the triazole Sch 39304 (SCH) against 14 isolates of Candida albicans. Testing was performed by broth microdilution and semisolid agar dilution with the following media, buffered to pH 7.0 with morpholinepropanesulfonic acid (MOPS): buffered yeast nitrogen base (BYNB), Eagle's minimal essential medium (EMEM), RPMI 1640 medium (RPMI), and synthetic amino acid medium for fungi (SAAMF). Inocula were standardized spectrophotometrically, and endpoints were defined by the complete absence of growth for AMB and by no more than 25% of the growth in the drug-free control for all other agents. Comparative analyses of median MICs, as determined by each test method, were made for all drug-medium combinations. Both methods yielded similar (+/- 1 twofold dilution) median MICs for AMB in EMEM and RPMI, 5FC in all media, and FLU in EMEM, RPMI, and SAAMF. In contrast, substantial between-method variations in median MICs were seen for AMB in BYNB and SAAMF, FLU In BYNB, and ITRA and SCH in all media. Interlaboratory concordance of median MICs was good for AMB, 5FC, and FLU but poor for ITRA and SCH in all media. Endpoint determinations were analyzed by use of kappa statistical analyses for evaluating the strength of observer agreement. Moderate to almost perfect interlaboratory agreement occurred with AMB and 5FC in all media and with FLU in EMEM, RPMI, and SAAMF, irrespective of the test method. Slight to almost perfect interlaboratory agreement occurred with ITRA and SCH in EMEM, RPMI, and SAAMF when tested by semisolid agar dilution but not broth microdilution. Kappa values assessing intralaboratory agreement between methods were high for 5FC in all media, for AMB in BYNB, ENEM, and RPMI, and for FLU in EMEM, RPMI, and SAAMF. One laboratory

  20. Improvement of Karmali agar by addition of polymyxin B for the detection of Campylobacter jejuni and C. coli in whole-chicken carcass rinse.

    PubMed

    Chon, Jung-Whan; Kim, Hyunsook; Yim, Jin-Hyeok; Song, Kwang-Young; Moon, Jin-San; Kim, Young-Jo; Seo, Kun-Ho

    2013-05-01

    The Karmali agar was modified by supplementation with a high concentration of polymyxin B. The goal of the study was to evaluate the effect of a high concentration of polymyxin B on the ability and selectivity of the modified Karmali agar to isolate Campylobacter jejuni and Campylobacter coli from whole chicken carcass rinse. A total of 80 whole chickens were rinsed with 400 mL of buffer peptone water. The rinsed samples were incubated with 2× blood-free modified Bolton enrichment broth for 48 h, and then streaked onto unmodified Karmali agar and modified Karmali agar supplemented with 100000 IU/L polymixin B (P-Karmali agar). The suspected colonies were finally confirmed by colony PCR. The P-Karmali agar exhibited a significantly better (P < 0.05) isolation rate than the unmodified Karmali agar (P-Karmali agar, 73.8%; unmodified Karmali agar, 33.8%). Moreover, the selectivity of the P-Karmali agar was also better (P < 0.05) than that of the other selective agar when comparing the number of contaminated plates (P-Karmali agar, 68.8%; unmodified Karmali agar, 87.5%) and growth index of competing flora (P-Karmali agar, 1.4; unmodified Karmali agar, 2.7). The improved selective agar excluded competing flora resistant to antibiotic agents in unmodified Karmali agar, increasing isolation rate and selectivity for C. jejuni and C. coli.

  1. Limitations of the clonal agar assay for the assessment of primary human ovarian tumour biopsies.

    PubMed Central

    Bertoncello, I.; Bradley, T. R.; Campbell, J. J.; Day, A. J.; McDonald, I. A.; McLeish, G. R.; Quinn, M. A.; Rome, R.; Hodgson, G. S.

    1982-01-01

    114 biopsy specimens from 70 patients with ovarian carcinoma at all stages of disease were submitted for assessment of clonogenic capacity in agar. A highly significant correlation was found between agar clonogenicity and patient survival after biopsy. However, problems related to inherent tumour heterogeneity, quality of sample and tissue disaggregation indicate that this technique may have limited applicability in the routine assessment of patients. Only 41 biopsy specimens (36%) from 31 patients (44.3%) complied with the prerequisite criteria for agar clonogenic assessment, namely: (a) the confirmed presence of malignant cells in the biopsy, (b) the ability to prepare a single-cell suspension, and (c) adequate viable cell numbers for assay. Furthermore, although the dominant patterns of agar clonogenic growth could be identified and correlated with stage of disease, the heterogeneity in both initial clonogenic capacity and "self-renewal" capacity assessed by the ability of primary clones to propagate in liquid culture and reclone in agar was too inconsistent for the assay to be used as a prognostic index for the individual patient. Images Figure PMID:7093117

  2. McKay agar enables routine quantification of the 'Streptococcus milleri' group in cystic fibrosis patients.

    PubMed

    Sibley, Christopher D; Grinwis, Margot E; Field, Tyler R; Parkins, Michael D; Norgaard, Jens C; Gregson, Daniel B; Rabin, Harvey R; Surette, Michael G

    2010-05-01

    The 'Streptococcus milleri' group (SMG) has recently been recognized as a contributor to bronchopulmonary disease in cystic fibrosis (CF). Routine detection and quantification is limited by current CF microbiology protocols. McKay agar was developed previously for the semi-selective isolation of this group. Here, McKay agar was validated against a panel of clinical SMG isolates, which revealed improved SMG recovery compared with Columbia blood agar. The effectiveness of this medium was evaluated by appending it to the standard CF sputum microbiology protocols in a clinical laboratory for a 6-month period. All unique colony types were isolated and identified by 16S rRNA gene sequencing. Whilst a wide variety of organisms were isolated, members of the SMG were the most prevalent bacteria cultured, and McKay agar allowed routine quantification of the SMG from 10(3) to >10(8) c.f.u. ml(-1) directly from sputum. All members of the SMG were detected [Streptococcus anginosus (40.7 %), Streptococcus intermedius (34.3 %) and Streptococcus constellatus (25 %)] with an overall prevalence rate of 40.6 % in our adult CF population. Without exception, samples where SMG isolates were cultured at 10(7) c.f.u. ml(-1) or greater were associated with pulmonary exacerbations. This study demonstrates that McKay agar can be used routinely to quantify the SMG from complex clinical samples.

  3. Nutrient agar with sodium chloride supplementation for presumptive detection of Moraxella catarrhalis in clinical specimens.

    PubMed

    Nishiyama, Hiroyuki; Saito, Ryoichi; Chida, Toshio; Sano, Kazumitsu; Tsuchiya, Tatsuyuki; Okamura, Noboru

    2012-04-01

    We previously reported that Nissui nutrient agar (N medium) promoted the growth of Moraxella catarrhalis but not commensal Neisseria spp. In the present study, we examined which constituent of N medium was responsible for the selective growth of M. catarrhalis using 209 M. catarrhalis and 100 commensal Neisseria spp. clinical strains. We found that peptone, but not meat extract or agar of N medium, had growth-promoting or growth-inhibiting ability with respect to M. catarrhalis and commensal Neisseria spp. Thus, we investigated the amino acid content of N peptone and found it had higher concentrations of amino acids than other commercial peptone products. On varying the sodium chloride concentration of reconstituted N medium, we noted that the concentration was an important factor in bacterial growth differences. Varying the sodium chloride concentration of other commercial nutrient agars achieved similar results to those for N medium. This is, to our knowledge, the first study observing that sodium chloride concentration is responsible for difference in growth between the two organisms. We also successfully isolated colonies of M. catarrhalis from respiratory specimens on N medium, whereas the growth of commensal Neisseria spp. was inhibited, and by adding bovine hematin and β-NAD we were able to isolate Haemophilus influenzae colonies as efficiently as with a chocolate agar. In conclusion, nutrient agar can be used as a medium for the preferential isolation of M. catarrhalis from upper respiratory tract specimens.

  4. Cell aggregation on agar as an indicator for cell-matrix adhesion: effects of opioids.

    PubMed

    Debruyne, Delphine; Mareel, Marc; Vanhoecke, Barbara; Bracke, Marc

    2009-09-01

    The slow aggregation assay is generally used to study the functionality of cell-cell adhesion complexes. Single cells are seeded on a semisolid agar substrate in a 96-well plate and the cells spontaneously aggregate. We used HEK FLAG-MOP cells that stably overexpress the mu opioid receptor and the mu-opioid-receptor-selective agonists DAMGO and morphine to study whether other factors than functionality of cell-cell adhesions complexes can contribute to changes in the pattern of slow aggregation on agar. HEK FLAG-MOP cells formed small compact aggregates. In the presence of DAMGO and morphine, larger and fewer aggregates were formed in comparison to the vehicle control. These aggregates were localized in the center of the agar surface, whereas in the vehicle control they were dispersed over the substrate. However, in suspension culture on a Gyrotory shaker, no stimulation of aggregation was observed by DAMGO and morphine, showing that opioids do not affect affinity. A dissociation experiment revealed that HEK FLAG-MOP aggregates formed in the absence or presence of opioids are resistant to de-adhesion. We demonstrated that the larger aggregates are neither the result of cell growth stimulation by DAMGO and morphine. Since manipulations of the substrate such as increasing the agar concentration or mixing agar with agarose induced the same changes in the pattern of slow aggregation as treatment with opioids, we suggest that cell-substrate adhesion may be involved in opioid-stimulated aggregation.

  5. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    PubMed

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes. PMID:25827444

  6. Novel grafted agar disks for the covalent immobilization of β-D-galactosidase.

    PubMed

    Wahba, Marwa I; Hassan, Mohamed E

    2015-12-01

    Novel grafted agar disks were prepared for the covalent immobilization of β-D-galactosidase (β-gal). The agar disks were activated through reacting with ethylenediamine or different molecular weights of Polyethyleneimine (PEI), followed by glutaraldehyde (GA). The modification of the agar gel and the binding of the enzyme were verified by Fourier Transform Infrared (FTIR) and elemental analysis. Moreover, the agar's activation process was optimized, and the amount of immobilized enzyme increased 3.44 folds, from 38.1 to 131.2 U/g gel, during the course of the optimization process. The immobilization of β-gal onto the activated agar disks caused its optimum temperature to increase from 45°C to 45-55°C. The optimum pH of the enzyme was also shifted towards the acidic side (3.6-4.6) after its immobilization. Additionally, the Michaelis-Menten constant (Km ) increased for the immobilized β-gal as compared to its free counterpart whereas the maximum reaction rate (Vmax ) decreased. The immobilized enzyme was also shown to retain 92.99% of its initial activity after being used for 15 consecutive times.

  7. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    PubMed

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.

  8. Strategies to improve the mechanical strength and water resistance of agar films for food packaging applications.

    PubMed

    Sousa, Ana M M; Gonçalves, Maria P

    2015-11-01

    Agar films possess several properties adequate for food packaging applications. However, their high cost-production and quality variations caused by physiological and environmental factors affecting wild seaweeds make them less attractive for industries. In this work, native (NA) and alkali-modified (AA) agars obtained from sustainably grown seaweeds (integrated multi-trophic aquaculture) were mixed with locust bean gum (LBG) to make 'knife-coated' films with fixed final concentration (1 wt%) and variable agar/LBG ratios. Agar films were easier to process upon LBG addition (viscosity increase and gelling character decrease of the film-forming solutions observed by dynamic oscillatory and steady shear measurements). The mechanical properties and water resistance were optimal for films with 50 and/or 75% LBG contents and best in the case of NA (cheaper to extract). These findings can help reduce the cost-production of agar packaging films. Moreover, the controlled cultivation of seaweeds can provide continuous and reliable feedstock for transformation industries. PMID:26256341

  9. Modification of Karmali agar by supplementation with potassium clavulanate for the isolation of Campylobacter from chicken carcass rinses.

    PubMed

    Chon, Jung-Whan; Kim, Hong-Seok; Kim, Dong-Hyeon; Kim, Hyunsook; Choi, In-Soo; Oh, Deog-Hwan; Seo, Kun-Ho

    2014-07-01

    The detection ability and selectivity of Karmali agar was improved by supplementation of an extended-spectrum β-lactamase inhibitor, potassium clavulanate. The optimum concentration of potassium clavulanate (0.5 μg/ml) in Karmali agar was determined by inoculation of 50 Campylobacter and 30 extended-spectrum β-lactamase-producing E. coli strains onto normal and modified Karmali agar containing various concentrations of the agent. Eighty retail carcasses were rinsed with 400 ml of buffered peptone water. The rinse samples were enriched in 2 × blood-free Bolton enrichment broth at 42°C for 48 h and then were streaked onto normal and modified Karmali agar containing 0.5 μg/ml potassium clavulanate. The suspicious colonies were subcultured on Columbia blood agar and confirmed by colony PCR. In chicken carcass samples, the modified Karmali agar showed a significantly greater isolation rate than normal Karmali agar (42.5 versus 21.3%; P < 0.05). Furthermore, the selectivity of the modified Karmali agar was also significantly higher (P < 0.05) than that of the normal Karmali agar, as seen by comparison of the number of contaminated agar plates (83.8 versus 97.5%) and the growth index (1.67 versus 2.91) of the non-Campylobacter colonies.

  10. Comparison of effectiveness of wood decay fungi maintained by annual subculture on agar and stored in sterile water for 18 years.

    PubMed

    Richter, Dana L; Kangas, Laura C; Smith, Jill K; Laks, Peter E

    2010-03-01

    Fourteen isolates of basidiomycete decay fungi (12 species) were maintained for 18 years on agar slants transferred annually and also stored as mycelium-agar cores under cold sterile water without subculture. Isolates stored by each method were evaluated for decay effectiveness using a standard laboratory accelerated soil-block decay test. Effectiveness was measured by mean percent mass loss of wood blocks. There was no significant difference (p < or = 0.05) in decay effectiveness between storage methods for 12 of the fungus isolates tested. For the 2 fungi that showed a significant difference in the amount of decay with respect to storage method, 1 fungus (Fomitopsis lilacinogilva) produced more decay by the strain maintained as an agar slant, while the other fungus (Trametes versicolor) produced more decay by the strain stored in sterile water. Results suggested that storage under sterile water is an easy and effective method to store isolates of decay fungi for long periods, but as with any microbial storage method, careful monitoring of isolates upon revival is necessary.

  11. Tissue equivalent proportional counter neutron monitor

    SciTech Connect

    Smith, R.C.; Strode, J.N.

    1980-06-01

    The Tissue Equivalent Proportional Counter (TEPC) is a sensitive area monitoring instrument that can be used either in place at fixed locations or as a portable neutron exposure measuring device. The system monitors low levels of neutron radiation exposure and has the capability of accurately measuring neutron exposure rates as low as 0.1 mrem/hr. The computerized analysis system calculates the quality factor which is important for situations where the neutron to gamma ratio may vary significantly and irregularly such as in fuel fabrication or handling facilities.

  12. Neutron spectrometry with He-3 proportional counters

    SciTech Connect

    Manolopoulou, M.; Fragopoulou, M.; Stoulos, S.; Vagena, E.; Westmeier, W.; Zamani, M.

    2011-07-01

    Helium filled proportional counters are widely used in the field of neutron detection and spectrometry. In this work the response of a commercially available He-3 counter is studied experimentally and calculated with Monte Carlo for the neutron energy range from 230 keV up to about 7 MeV. The calculated response of the system is used to determine neutron yield energy distribution emitted from an extended {sup nat}U/Pb assembly irradiated with 1.6 GeV deuterons. The results are in acceptable agreement with the calculated neutron distribution with DCM-DEM code. (authors)

  13. Digital image quantification of siderophores on agar plates.

    PubMed

    Andrews, Megan Y; Santelli, Cara M; Duckworth, Owen W

    2016-03-01

    This article presents visual image data and detailed methodology for the use of a new method for quantifying the exudation of siderophores during fungal growth. The data include images showing time series for calibration, fungal exudation, and negative controls, as well as replication accuracy information. In addition, we provide detailed protocols for making CAS assay layer plates, the digital analysis protocol for determining area of color change, and discuss growth media that do and do not work with the layer plate method. The results of these data, their interpretation, and further discussion can be found in Andrews et al., 2016 [1]. PMID:26937467

  14. Evaluation of the antibacterial effects of vancomycin hydrochloride released from agar-gelatin-bioactive glass composites.

    PubMed

    Rivadeneira, Josefina; Di Virgilio, Ana Laura; Audisio, M Carina; Boccaccini, Aldo R; Gorustovich, Alejandro A

    2015-01-13

    The aim of this work was to evaluate the perfomance of agar-gelatin (AG) composites and AG-containing 45S5 bioactive glass (BG) microparticles (AGBG) in relation to their water uptake capacity, sustained release of a drug over time, and antibacterial effects. The composites were fabricated by the gel-casting method. To impart the local drug release capacity, vancomycin hydrochloride (VC) was loaded in the composites in concentrations of 0.5 and 1 mg ml(-1). VC release was assessed in distilled water at 37 °C up to 72 h and quantified spectrophotometrically. The antibacterial activity of composites was evaluated by the inhibition zone test and the plate count method. The experiments were performed in vitro up to 48 h on three staphylococcus strains: Staphylococcus aureus ATCC29213, S. aureus ATCC6538 and Staphylococcus epidermidis ATCC12228. The results showed that the addition of BG to AG composites did not affect the degree of water uptake. The release of VC was significantly affected by the presence of BG. VC release was higher from AGBGVC films than from AGVC ones over prolonged incubation times. Bacterial inhibition zones were found around the composites. The halos were larger when the cells were put in contact with AGVC composites than when they were put in contact with AGBGVC ones. Nevertheless, the viable count method demonstrated that the composites inhibited Staphylococcus cell growth with no statistical differences. In conclusion, the addition of BG did not reflect an improvement in the parameters studied. On the other hand, composites loaded with VC would have a role in prophylaxis against bacterial infection.

  15. Effect of Diethylaminoethyl Dextran on the Growth of Mycoplasma in Agar

    PubMed Central

    Tauraso, Nicola M.

    1967-01-01

    The growth of certain strains of Mycoplasma is inhibited by substances present in commercial agar preparations. The addition of diethylaminoethyl (DEAE) dextran (10 mg per 100 ml) to agar media appears to enhance the growth of some strains. Of eight strains initially tested, the presence of DEAE dextran grossly enhanced the growth of three strains. One strain appeared not to be affected, and a clearly enhancing effect was not evident with four strains. Quantitative studies revealed that growth enhancement varied from 10 colony-forming units (CFU) for M. hominis type II (strain Campo) to 103.3 CFU for M. pulmonis (strain 880). The growth-enhancing effect is probably due to the ability of DEAE dextran to bind the sulfated polysaccharide moieties in agar and not to the DEAE dextran, per se. Images PMID:6025444

  16. Expression of an accessory cell phenotype by hairy cells during lymphocyte colony formation in agar culture.

    PubMed

    Farcet, J P; Gourdin, M F; Testa, U; Andre, C; Jouault, H; Reyes, F

    1983-01-01

    Human T lymphocytes require the cooperation of accessory cells to generate lymphocyte colonies in agar culture under PHA stimulation. Various hairy cell enriched fractions, as well as normal monocytes, have been found to be able to initiate colony formation by normal lymphocytes. Leukemic monocytes from CMML patients were also effective, but not the leukemic lymphocytes from CLL patients. The phenotype expressed by HC in agar colonies was further studied using cell surface and enzymatic markers. We have concluded that HC in agar culture in the presence of both normal T lymphocytes and PHA lose the B phenotype that they express in vivo and function like an accessory cell in contrast to normal or leukemic B lymphocytes. PMID:6601222

  17. Proportional Smile Design: Using the Recurring Esthetic Dental Proportion to Correlate the Widths and Lengths of the Maxillary Anterior Teeth with the Size of the Face.

    PubMed

    Ward, Daniel H

    2015-07-01

    Proportional smile design is a useful tool for evaluating and designing smiles that are in harmony with the face. Although not always observed in nature, the recurring esthetic dental proportion is preferred by dentists surveyed to the width proportions observed in nature with normal-length teeth. The width/length ratio of the central incisor is a key determinant in providing a smile that is pleasing to dentists. Using the desired tooth length while maintaining the preferred 78% width/length ratio of the central incisor in conjunction with the recommended recurring esthetic dental proportion is a good method for designing a smile balanced with the face. PMID:26140969

  18. Proportional Smile Design: Using the Recurring Esthetic Dental Proportion to Correlate the Widths and Lengths of the Maxillary Anterior Teeth with the Size of the Face.

    PubMed

    Ward, Daniel H

    2015-07-01

    Proportional smile design is a useful tool for evaluating and designing smiles that are in harmony with the face. Although not always observed in nature, the recurring esthetic dental proportion is preferred by dentists surveyed to the width proportions observed in nature with normal-length teeth. The width/length ratio of the central incisor is a key determinant in providing a smile that is pleasing to dentists. Using the desired tooth length while maintaining the preferred 78% width/length ratio of the central incisor in conjunction with the recommended recurring esthetic dental proportion is a good method for designing a smile balanced with the face.

  19. Continuously proportional variable geometry turbocharger system and method of control

    SciTech Connect

    Younessi, R.; Rini, G.T.

    1992-06-23

    This patent describes a system for performing closed loop control of a variable geometry turbocharger (VGT) utilized in an internal combustion engine. It comprises VGT actuator means for changing the geometric configuration of the VGT in response to an actuator control signal; sensor means for detecting selected engine operating parameters including a VGT actuator parameter and an engine intake manifold parameter, and generating output signals representative thereof; means for outputting a target VGT actuator parameter value and a target intake manifold parameter valve based on the values of selected sensor means output signals; means for determining whether the engine is in a steady state or a transient state of operation based on the values of selected sensor means output signals; and means for developing an actuator control signal based on one of the target parameter values as a function of the determined engine operating state.

  20. ProPortal: A Database for Prochlorococcus

    DOE Data Explorer

    Huang, Katherine [Chisholm lab, MIT

    Prochlorococcus is a marine cyanobacterium that numerically dominates the mid-latitude oceans, and is the smallest known oxygenic phototroph. All isolates described thus far can be assigned to either a tightly clustered high-light (HL) adapted clade, or a more divergent low-light (LL) adapted group. They are closely related to, but distinct from, marine Synechococcus. The genomes of 12 strains have been sequenced and they range in size from 1.6 to 2.6 Mbp. They represent diverse lineages, spanning the rRNA diversity (97 to 99.93% similarity) of cultured representatives of this group. Our analyses of these genomes inform our understanding of how adaptation occurs in the oceans along gradients of light, nutrients, and other environmental factors, providing essential context for interpreting rapidly expanding metagenomic datasets. [Copied from http://proportal.mit.edu/project/prochlorococcus/] ProPortal allows users to browse and search genome date for not only Prochlorococcus, but Cyanophage and Synechococcus. Microarray data, environmental cell concentration data, and metagenome information are also available.

  1. Kalman-predictive-proportional-integral-derivative (KPPID)

    SciTech Connect

    Fluerasu, A.; Sutton, M.

    2004-12-17

    With third generation synchrotron X-ray sources, it is possible to acquire detailed structural information about the system under study with time resolution orders of magnitude faster than was possible a few years ago. These advances have generated many new challenges for changing and controlling the state of the system on very short time scales, in a uniform and controlled manner. For our particular X-ray experiments on crystallization or order-disorder phase transitions in metallic alloys, we need to change the sample temperature by hundreds of degrees as fast as possible while avoiding over or under shooting. To achieve this, we designed and implemented a computer-controlled temperature tracking system which combines standard Proportional-Integral-Derivative (PID) feedback, thermal modeling and finite difference thermal calculations (feedforward), and Kalman filtering of the temperature readings in order to reduce the noise. The resulting Kalman-Predictive-Proportional-Integral-Derivative (KPPID) algorithm allows us to obtain accurate control, to minimize the response time and to avoid over/under shooting, even in systems with inherently noisy temperature readings and time delays. The KPPID temperature controller was successfully implemented at the Advanced Photon Source at Argonne National Laboratories and was used to perform coherent and time-resolved X-ray diffraction experiments.

  2. Radiation effects on agar, alginates and carrageenan to be used as food additives

    NASA Astrophysics Data System (ADS)

    Aliste, A. J. A. J.; Vieira, F. F. F. F.; Del Mastro, N. L. N. L.

    2000-03-01

    Agar, alginates and carrageenan are hydrocolloids that induce stabilization of physical properties of the food product during shelf life and prevention of undesirable changes such as moisture migration, gas cell coalescence or textural profile changes. In this work, agar, alginates and carrageenan was irradiated as powder with different doses (0-10 kGy) of Co-60 and the rheological functional performance of water solutions of these irradiated additives was studied. The results are analyzed taking in account the future applications of those additives in irradiated foods.

  3. Agar-polydimethylsiloxane devices for quantitative investigation of oviposition behaviour of adult Drosophila melanogaster

    PubMed Central

    Leung, Jacob C. K.; Taylor-Kamall, Rhodri W.; Hilliker, Arthur J.; Rezai, Pouya

    2015-01-01

    Drosophila melanogaster (fruit fly) is a model organism and its behaviours including oviposition (egg-laying) on agar substrates have been widely used for assessment of a variety of biological processes in flies. Physical and chemical properties of the substrate are the dominant factors affecting Drosophila's oviposition, but they have not been investigated precisely and parametrically with the existing manual approaches. As a result, many behavioral questions about Drosophila oviposition, such as the combined effects of the aforementioned substrate properties (e.g., exposure area, sugar content, and stiffness) on oviposition and viability, and their threshold values, are yet to be answered. In this paper, we have devised a simple, easily implementable, and novel methodology that allows for modification of physical and chemical composition of agar substrates in order to quantitatively study survival and oviposition of adult fruit flies in an accurate and repeatable manner. Agar substrates have been modified by surface patterning using single and hexagonally arrayed through-hole polydimethylsiloxane (PDMS) membranes with various diameters and interspacing, as well as by substrate stiffness and sugar content modification via alteration of chemical components. While pure PDMS substrates showed a significant lethal effect on flies, a 0.5 mm diameter through-hole access to agar was found to abruptly increase the survival of adult flies to more than 93%. Flies avoided ovipositing on pure PDMS and on top of substrates with 0.5 mm diameter agar exposure areas. At a hole diameter of 2 mm (i.e., 0.25% exposure area) or larger, eggs were observed to be laid predominately inside the through-holes and along the edges of the PDMS-agar interface, showing a trending increase in site selection with 4 mm (i.e., 1% exposure area threshold) demonstrating natural oviposition rates similar to pure agar. The surface-modified agar-PDMS hybrid devices and the threshold values

  4. A proportional temperature controller with automatic shutoff

    NASA Astrophysics Data System (ADS)

    Lucich, G. M.; Holland, P. W.

    1980-08-01

    A sensitive, proportional temperature controller useful in the temperature range from 40 to 400 C with an accuracy of plus or minus 0.1 C is described. It is potentially useful for regulating temperatures in air chambers, liquid baths, furnaces and reaction vessels and for other applications. This instrument was developed to control the duration and temperature of the heating cycle of a charcoal filled adsorber that is part of a special helium analyzer. The controller was made from commercially available parts and can be easily modified to provide continuous temperature control. The circuit is solid state and employs no electromechanical devices. Over a 2 year period of use as a component of the special helium analyzer, this temperature controller performed successfully and required no maintenance.

  5. TRIAC/SCR proportional control circuit

    DOEpatents

    Hughes, W.J.

    1999-04-06

    A power controller device is disclosed which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the ``reset`` input of a R-S flip flop, while an ``0`` crossing detector controls the ``set`` input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the ``reset`` and ``set`` inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations. 9 figs.

  6. TRIAC/SCR proportional control circuit

    DOEpatents

    Hughes, Wallace J.

    1999-01-01

    A power controller device which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the "reset" input of a R-S flip flop, while an "0" crossing detector controls the "set" input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the "reset" and "set" inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations.

  7. Gaseous fuel and air proportioning device

    SciTech Connect

    Lassanske, G. G.; Poshlman, A. G.

    1984-01-10

    The device for proportioning a gaseous fuel and air for combustion in an internal combustion engine includes a plate-like first member having a peripheral edge portion and a second member cooperating with the first member having a peripheral edge portion and a second member cooperating with the first member to define a mixing chamber having an outlet adapted to be connected in communication with the air intake of the engine carburetor. The second member also includes an annular portion having an arcuate first wall which is convex to and spaced from the peripheral edge portion of the first member to define an annular venturi having an inlet in communication with the atmosphere and an annular outlet in communication with the mixing chamber. A base member or second wall cooperates with the arcuate wall to form a substantially closed, annular plenum chamber into which a gaseous fuel, such as natural gas, is admitted when the engine is to be operated on the gaseous fuel. The gaseous fuel is admitted into the mixing chamber from the plenum chamber through one or more ports in the arcuate wall at or in the vicinity of the throat of the annular venturi. A pair of circumferentially spaced radially extending partitions located on the opposite sides of each port define a radially extending venturi which has a throat located at or in the vicinity of the port and serves to induce flow of the gaseous fuel through the corresponding port. The proportioning device preferably is arranged to fit inside the housing of an existing air cleaner.

  8. Time- and media-saving testing and identification of microorganisms by multipoint inoculation on undivided agar plates.

    PubMed Central

    Burman, L G; Ostensson, R

    1978-01-01

    Motility and various biochemical activities of isolates of bacteria and yeasts were tested on undivided agar plates by using a simple, manually operated multipoint inoculation apparatus that allowed the analysis of 25 isolates per 9-cm-diameter petri plate. Fermentation of all 17 carbohydrates tested as well as 13 other biochemical activities commonly used for identification of bacteria were readily demonstrated by the multipoint inoculation plate method, and the results agreed very well with those of conventional tube tests. In addition to speedy inoculation and low cost of materials, the multipoint inoculation plate method offers several other advantages when compared with conventional tube tests or with some of the manufactured test kits currently available for recognizing members of the family Enterobacteriaceae. Images PMID:359588

  9. Improved Margin of Error Estimates for Proportions in Business: An Educational Example

    ERIC Educational Resources Information Center

    Arzumanyan, George; Halcoussis, Dennis; Phillips, G. Michael

    2015-01-01

    This paper presents the Agresti & Coull "Adjusted Wald" method for computing confidence intervals and margins of error for common proportion estimates. The presented method is easily implementable by business students and practitioners and provides more accurate estimates of proportions particularly in extreme samples and small…

  10. Applying Agar's Concept of "Languaculture" to Explain Asian Students' Experiences in the Australian Tertiary Context

    ERIC Educational Resources Information Center

    Norris, Lindy; Tsedendamba, Nara

    2015-01-01

    This paper reports part of a broader qualitative case study of Asian students "translation" (Agar, 2006) to study in an Australian university. The paper is concerned with the experiences of eight participants and their involvement in a training programme in the use of language learning strategies (LLS) to support their engagement with…

  11. THE MICROGARDENING COOKBOOK, DIRECTIONS FOR PREPARING DISHES AND TUBES OF STERILE NUTRIENT AGAR.

    ERIC Educational Resources Information Center

    CHANDLER, MARION N.

    THIS BOOKLET WAS PREPARED FOR TEACHER USE IN ASSOCIATION WITH THE ELEMENTARY SCIENCE STUDY UNIT "MICROGARDENING." IT CONTAINS DIRECTIONS FOR PREPARING CULTURE DISHES AND TUBES OF NUTRIENT STERILE AGAR FOR FUNGAL AND/OR BACTERIAL GROWTH. IT INCLUDES (1) LISTS OF NEEDED SUPPLIES AND EQUIPMENT, (2) DIRECTIONS FOR THE PREPARATION AND STERILIZATION OF…

  12. Investigation of dental alginate and agar impression materials as a brain simulant for ballistic testing.

    PubMed

    Falland-Cheung, Lisa; Piccione, Neil; Zhao, Tianqi; Lazarjan, Milad Soltanipour; Hanlin, Suzanne; Jermy, Mark; Waddell, J Neil

    2016-06-01

    Routine forensic research into in vitro skin/skull/brain ballistic blood backspatter behavior has traditionally used gelatin at a 1:10 Water:Powder (W:P) ratio by volume as a brain simulant. A limitation of gelatin is its high elasticity compared to brain tissue. Therefore this study investigated the use of dental alginate and agar impression materials as a brain simulant for ballistic testing. Fresh deer brain, alginate (W:P ratio 91.5:8.5) and agar (W:P ratio 81:19) specimens (n=10) (11×22×33mm) were placed in transparent Perspex boxes of the same internal dimensions prior to shooting with a 0.22inch caliber high velocity air gun. Quantitative analysis to establish kinetic energy loss, vertical displacement elastic behavior and qualitative analysis to establish elasticity behavior was done via high-speed camera footage (SA5, Photron, Japan) using Photron Fastcam Viewer software (Version 3.5.1, Photron, Japan) and visual observation. Damage mechanisms and behavior were qualitatively established by observation of the materials during and after shooting. The qualitative analysis found that of the two simulant materials tested, agar behaved more like brain in terms of damage and showed similar mechanical response to brain during the passage of the projectile, in terms of energy absorption and vertical velocity displacement. In conclusion agar showed a mechanical and subsequent damage response that was similar to brain compared to alginate.

  13. Seasonal variation in the biomass and agar yield from Gracilaria cervicornis and Hydropuntia cornea from Brazil.

    PubMed

    Marinho-Soriano, E; Silva, T S; Moreira, W S

    2001-04-01

    Seasonality of biomass and agar yield from two agarophytes (G. cervicornis and H. cornea) was determined. The biomass from G. cervicornis was higher (390 g m-2) during the dry season and lower during the rainy season (129 g m-2). The data analysis for G. cervicornis revealed a significant seasonal variation (P < 0.05). H. cornea did not show a clear seasonal variation and was present only from March to August. The peak in biomass for this species was recorded in April (383 g m-2) and was significantly different from the other months (P < 0.05). The agar yield for G. cervicornis varied from 11% to 20%, with generally higher values recorded during the dry season. The agar yield showed a highly significant variation (P < 0.001). Agar yield from H. cornea ranged from 29% to 41%, with a peak recorded in June. The results above indicate that H. cornea can be considered a good candidate for commercial use.

  14. Agar media that indicate acid production from sorbitol by oral microorganisms.

    PubMed

    Kalfas, S; Edwardsson, S

    1985-12-01

    Two varieties of agar medium (Trypticase [BBL Microbiology Systems]-serum-sorbitol-bromcresol purple agar [TSSB] and Trypticase-blood-sorbitol-CaCO3 agar [TBSCa]) indicating microbial acid production from sorbitol were tested. The media were devised for use in studies on the prevalence of sorbitol-fermenting human oral microorganisms incubated in an anaerobic or microaerophilic atmosphere containing 5 to 6% CO2. TSSB contains bromcresol purple as the pH indicator and NaHCO3 as the main buffering salt. TBSCa contains CaCO3 as both the buffering salt and the indicator of acid production. The growth yield of pure cultures of oral microorganisms on TBSCa was shown to equal that on blood agar incubated under similar conditions. TSSB inhibited the growth of several bacteria to various extents. The recovery of sorbitol-fermenting microorganisms from oral specimens was the greatest when the specimens were assayed with TBSCa. The poorer results obtained with TSSB were mainly due to the decoloration of the pH indicator in this medium and the presence of greater numbers of sorbitol false-positive colonies.

  15. Draft Genome Sequence of the Novel Agar-Digesting Marine Bacterium HQM9▿

    PubMed Central

    Du, Zongjun; Zhang, Zhewen; Miao, Tingting; Wu, Jiayan; Lü, Guoqiang; Yu, Jun; Xiao, Jingfa; Chen, Guanjun

    2011-01-01

    Strain HQM9, an aerobic, rod-shaped marine bacterium from red algae, can produce agarases and liquefy solid plating media efficiently when agar is used as a coagulant. Here we report the draft genome sequence and the initial findings from a preliminary analysis of strain HQM9, which should be a novel species of Flavobacteriaceae. PMID:21725015

  16. Investigation of dental alginate and agar impression materials as a brain simulant for ballistic testing.

    PubMed

    Falland-Cheung, Lisa; Piccione, Neil; Zhao, Tianqi; Lazarjan, Milad Soltanipour; Hanlin, Suzanne; Jermy, Mark; Waddell, J Neil

    2016-06-01

    Routine forensic research into in vitro skin/skull/brain ballistic blood backspatter behavior has traditionally used gelatin at a 1:10 Water:Powder (W:P) ratio by volume as a brain simulant. A limitation of gelatin is its high elasticity compared to brain tissue. Therefore this study investigated the use of dental alginate and agar impression materials as a brain simulant for ballistic testing. Fresh deer brain, alginate (W:P ratio 91.5:8.5) and agar (W:P ratio 81:19) specimens (n=10) (11×22×33mm) were placed in transparent Perspex boxes of the same internal dimensions prior to shooting with a 0.22inch caliber high velocity air gun. Quantitative analysis to establish kinetic energy loss, vertical displacement elastic behavior and qualitative analysis to establish elasticity behavior was done via high-speed camera footage (SA5, Photron, Japan) using Photron Fastcam Viewer software (Version 3.5.1, Photron, Japan) and visual observation. Damage mechanisms and behavior were qualitatively established by observation of the materials during and after shooting. The qualitative analysis found that of the two simulant materials tested, agar behaved more like brain in terms of damage and showed similar mechanical response to brain during the passage of the projectile, in terms of energy absorption and vertical velocity displacement. In conclusion agar showed a mechanical and subsequent damage response that was similar to brain compared to alginate. PMID:27131216

  17. Population cell differentiation of Serratia marcescens on agar surface and in broth culture.

    PubMed

    Lai, H C; Lai, M J; Lin-Chao, S; Lu, K T; Ho, S W

    1997-11-01

    The bacterium Serratia marcescens shows population surface migration (swarming) phenomenum on an LB swarming plate, and differentiated cells can be observed at the swarming front. How the cell population differentiates during swarming on the agar surface is not known, neither is it clear whether cells with differentiated characteristics can be observed in broth culture. To monitor the population cell differentiation in a highly sensitive way without cell destruction, experiments were designed using bacterial luciferase genes luxAB as the reporter genes to allow direct monitoring of the differentiating cells through bioluminescence. An isogenic S. marcescens strain was constructed with luxAB under the control of the promoter of flagellin gene hag (phag::luxAB). Patterns of cell differentiation were monitored either by direct X-ray film exposure and/or by Autolumat luminometer detection. Results show that population cell differentiation on the agar surface occurs first in a temporal and then spatial way during colonial growth. It was also found that cells harvested from both the spreading agar plate and broth culture showed differentiation patterns similar to those from swarming cells, suggesting that the agar surface culture may not be essential for the formation of differentiated cells.

  18. Evolutionary consequences of putative intra- and interspecific hybridization in agaric fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agaric fungi of the southern Appalachians including the Great Smoky Mountains National Park are often heterozygous for the rDNA internal transcribed spacer region (ITS) with >42% of collections showing some level of heterozygosity for indels and/or base-pair substitutions. For these collections, int...

  19. Alternative plasticizers for the production of thermo-compressed agar films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One percent agar (% wt) was dissolved in the deep eutectic solvent (DES), (2-hydroxyethyl) trimethylammonium chloride/urea at a 1:2 molar ratio, and successfully Electrospun into nanofibers. An existing electrospinning set-up, operated at 50 deg C, was adapted for use with an ethanol bath to collect...

  20. Thallium toxicosis in a dog consequent to ingestion of Mycoplasma agar plates.

    PubMed

    Puschner, Birgit; Basso, Marguerite M; Graham, Thomas W

    2012-01-01

    A 1-year-old dog ingested a mixture of blood agar and Mycoplasma agar plates. The Mycoplasma agar plates contained thallium acetate, which resulted in an estimated minimum dose of 5 mg thallium acetate/kg bodyweight. Clinical signs over the course of 2-3 weeks included vomiting, diarrhea, weight loss, alopecia, dysphonia, ataxia, paresthesia, intension tremors, megaesophagus with subsequent aspiration pneumonia, and several seizure episodes. The dog was treated with intravenous fluids and placement of a gastric feeding tube. Thallium concentrations in hair were 8.2 µg/g in samples taken on day 19, 16.4 µg/g in samples taken 3 months after exposure, 13.4 µg/g in samples taken 5 months after exposure, and nondetectable in samples taken 7 months after exposure. The blood thallium concentration was 190 µg/l on day 19 and nondetec table 3 months after exposure. Megaesophagus and dysphonia continued for 10 months after exposure. This case of thallium poisoning following ingestion of mycoplasma agar plates demonstrates that unusual sources of thallium still exist and suggests that thallium toxicosis should be included in the list of differential diagnoses in dogs presented with megaesophagus, especially if alopecia and other unexplained peripheral neuropathies are present. Hair and blood samples are useful specimens to reach an accurate diagnosis even if taken several weeks post exposure. The postexposure blood and hair thallium concentrations reported in this case are useful data for diagnosticians investigating dogs with potential thallium poisoning.

  1. Long-term maintenance of fungal cultures on perlite in cryovials - an alternative for agar slants.

    PubMed

    Homolka, L; Lisá, L

    2008-01-01

    Cultures of 33 basidiomycete strains out of 35 tested were viable with unchanged characteristics after four years of maintenance on perlite in cryovials. These cultures can be a good substitute for agar cultures in long-term maintenance of fungi. For comparison, the storage under oil was evaluated but it turned out to be unsuitable for the majority of our cultures.

  2. Evaluation of Use of a New Chromogenic Agar in Detection of Urinary Tract Pathogens

    PubMed Central

    Samra, Z.; Heifetz, M.; Talmor, J.; Bain, E.; Bahar, J.

    1998-01-01

    CHROMagar Orientation, a new chromogenic medium, was evaluated for the detection and differentiation of gram-positive and gram-negative pathogenic microorganisms in 900 urine samples from hospitalized patients. Performance characteristics of the medium were evaluated in comparison to those of 5% sheep blood and MacConkey agars by direct inoculation of the urine samples on the three media. Four gram-negative and two gram-positive strains as well as one yeast control strain from the American Type Culture Collection were used to ensure quality control. CHROMagar Orientation succeeded in detecting all the urine pathogens that were detected by the reference media, including gram-negative bacilli, staphylococci, streptococci, and yeasts. Colony color and morphology on CHROMagar Orientation accurately differentiated Escherichia coli, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, and Acinetobacter spp. Owing to the similarity in the pigmentation produced by Klebsiella, Enterobacter, and Citrobacter isolates, the medium failed to distinguish among them; however, these isolates were easily recognized as coliforms because of their metallic blue coloration. Staphylococci were clearly perceptible: S. aureus and S. epidermidis grow in regular-size colonies that range from opaque white to yellowish, and S. saprophyticus produces opaque pink colonies. All streptococcus strains, including those from groups B and C, were detected. They grow as undifferentiated flat dry diffused colonies, and additional tests were required for identification. Enterococci were easily discriminated by their strong turquoise pigmentation and their typical growth on the agar’s surface. Yeast grow in typical creamy wet convex colonies. The accuracy of antibiotic susceptibility determinations according to standard methods was also tested by picking isolates directly from CHROMagar Orientation. The results showed excellent correlation with those obtained with microorganisms picked from

  3. Comparative performance of Thin Layer Agar and Löwenstein-Jensen culture for diagnosis of tuberculosis.

    PubMed

    Battaglioli, T; Rintiswati, N; Martin, A; Palupi, K R; Bernaerts, G; Dwihardiani, B; Ahmad, R A; Matthys, F; Mahendradhata, Y; Van der Stuyft, P

    2013-11-01

    Sputum smear microscopy for the diagnosis of tuberculosis (TB) is cheap and simple but its sensitivity is low. Culture on Löwenstein-Jensen (LJ) is more sensitive but it takes a long time to yield results. Thin-Layer Agar (TLA) culture was suggested as an equally sensitive and faster alternative. We evaluated the performance of TLA for diagnosing TB in Jogjakarta, Indonesia. People with suspected TB presenting from July 2010 to July 2011 to two chest clinics of the National TB Control Programme network of Jogjakarta were eligible for inclusion. A sputum sample was sent to the Gadjah Mada University microbiology laboratory for concentration, smearing, Ziehl-Neelsen staining and culture on LJ and TLA. Sensitivity of cultures was evaluated against a composite reference standard (any positive culture). Time to detection of Mycobacteria was recorded. Out of 1414 samples, 164 (12%) were smear positive, 99 (7%) were scanty and 1151 (81%) were negative. On TLA and LJ respectively, 168 (12%) and 149 (11%) samples were positive, 72 (5%) and 32 (2%) were contaminated (κ = 0.64; 95% CI 0.59-0.69, p <0.01). Using the reference standard, 196 (14%) TB cases were identified. The sensitivity of TLA was 0.86 (95% CI 0.80-0.90), significantly higher (p 0.03) than for LJ (0.76; 95% CI 0.69-0.81). The median time to detection in days was significantly shorter (p <0.01) for TLA (12; 95% CI 11-13) than for LJ (44; 95% CI 43-45). TLA is a rapid and sensitive method for the diagnosis of TB. Implementation studies to evaluate the cost-effectiveness and impact of its introduction into programmatic settings are urgently needed.

  4. The elite athlete - assessing body shape, size, proportion and composition.

    PubMed

    Kerr, D A; Ackland, T R; Schreiner, A B

    1995-03-01

    In the quest to optimize performance of the elite athlete the sport scientist has sought to determine the ideal physique for a given sport or event. For some sports, specific structural characteristics offer definite performance advantages; for example in rowing, in addition to height, a large arm span has been identified as important. In other sports. such as long distance running, low levels of adiposity or 'fatness' appear to be linked with faster running times. There are four areas where appraisal of the athlete's physique can provide useful information: (1) identification of talented athletes; (2) to assess and monitor the growing athlete; (3) to monitor training and performance; and (4) to determine 'race weight' in weight-category sports. As a research tool a particular method must be reliable and valid. Other considerations include how expensive the method is, if it is suitable for a field situation and if large amounts of data on a number of subjects can be collected quickly. The method should be safe for both the athlete and the tester and provide useful feedback for the athlete or coach. Anthropometry, with training is able to fulfil most of these criteria and is the most widely used method of physique assessment in sports science. Large anthropometric data bases have been collected on elite athletes at Olympic games and world championships according to a standard protocol. Kinanthropometry, which has developed from anthropometry, is concerned with measurement and evaluation of different aspects of human movement and individual variation in body shape, size, proportion and composition. For the assessment of adiposity a sum of skinfolds, usually over six sites, is most commonly used rather than percentage body fat formulae. Muscle mass can be assessed indirectly through girth and corrected girth measurements. Limb lengths and breadths are used to assess skeletal structure and proportional differences in limb size. The anthropometric methods most commonly

  5. Standardization of disk diffusion and agar dilution susceptibility tests for Neisseria gonorrhoeae: interpretive criteria and quality control guidelines for ceftriaxone, penicillin, spectinomycin, and tetracycline.

    PubMed Central

    Jones, R N; Gavan, T L; Thornsberry, C; Fuchs, P C; Gerlach, E H; Knapp, J S; Murray, P; Washington, J A

    1989-01-01

    A six-laboratory study developed a standardized method for determining the susceptibilities of Neisseria gonorrhoeae strains to penicillin, tetracycline, spectinomycin, and ceftriaxone. Three quality control organisms were also selected, and quality assurance guidelines were initially generated for the disk diffusion and agar dilution methods. The medium recommended for gonococcal susceptibility testing was GC agar with a defined "XV-like" supplement. The supplement should be free of cysteine, a component implicated in the inactivation of some newer beta-lactam compounds. Penicillin, tetracycline, spectinomycin, and ceftriaxone were stable in agar plates stored at 3 to 5 degrees C for at least 2 weeks. Numerous GC agar and drug disk lots were used during the trials without significant variation in test results. Several other gonococcal strains were recommended for additional medium quality assurance. The disk quality control zone limits were established for N. gonorrhoeae ATCC 49226 (formerly CDC F-18) and Staphylococcus aureus ATCC 25923. MIC quality control ranges were also developed for N. gonorrhoeae ATCC 49226 and S. aureus ATCC 29213. The interpretive criteria for penicillin were as follows: susceptibility, greater than or equal to 47 mm (diameter of inhibition zone) (less than or equal to 0.06 micrograms/ml [MIC]); resistance, less than or equal to 26 mm (greater than or equal to 2 micrograms/ml). For tetracycline they were as follows: susceptibility, greater than or equal to 38 mm (less than or equal to 0.25 microgram/ml); resistance, less than or equal to 30 mm (greater than or equal to 2 micrograms/ml). For spectinomycin they were as follows: susceptibility, >/= 18 mm (/= 128 micrograms/ml). For ceftriaxone susceptibility, the criterion was >/= 35 mm (

  6. Rapid Identification of Positive Blood Cultures by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Using Prewarmed Agar Plates

    PubMed Central

    Bhatti, M. M.; Boonlayangoor, S.; Beavis, K. G.

    2014-01-01

    This study describes an inexpensive and straightforward method for identifying bacteria by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) directly from positive blood cultures using prewarmed agar plates. Different inoculation methods and incubation times were evaluated to determine the optimal conditions. The two methods using pelleted material from positive culture bottles performed best. In particular, the pellet streak method correctly identified 94% of the Gram negatives following 4 h of incubation and 98% of the Gram positives following 6 h of incubation. PMID:25232166

  7. Rapid identification of positive blood cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry using prewarmed agar plates.

    PubMed

    Bhatti, M M; Boonlayangoor, S; Beavis, K G; Tesic, V

    2014-12-01

    This study describes an inexpensive and straightforward method for identifying bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) directly from positive blood cultures using prewarmed agar plates. Different inoculation methods and incubation times were evaluated to determine the optimal conditions. The two methods using pelleted material from positive culture bottles performed best. In particular, the pellet streak method correctly identified 94% of the Gram negatives following 4 h of incubation and 98% of the Gram positives following 6 h of incubation.

  8. Effect of impact stress on microbial recovery on an agar surface.

    PubMed Central

    Stewart, S L; Grinshpun, S A; Willeke, K; Terzieva, S; Ulevicius, V; Donnelly, J

    1995-01-01

    Microbial stress due to the impaction of microorganisms onto an agar collection surface was studied experimentally. The relative recovery rates of aerosolized Pseudomonas fluorescens and Micrococcus luteus were determined as a function of the impaction velocity by using a moving agar slide impactor operating over a flow rate range from 3.8 to 40 liters/min yielding impaction velocities from 24 to 250 m/s. As a reference, the sixth stage of the Andersen Six-Stage Viable Particle Sizing Sampler was used at its operating flow rate of 28.3 liters/min (24 m/s). At a collection efficiency of close to 100% for the agar slide impactor, an increase in sampling flow rate and, therefore, in impaction velocity produced a significant decline in the percentage of microorganisms recovered. Conversely, when the collection efficiency was less than 100%, greater recovery and lower injury rates occurred. The highest relative rate of recovery (approximately 51% for P. fluorescens and approximately 62% for M. luteus) was obtained on the complete (Trypticase soy agar) medium at 40 and 24 m/s (6.4 and 3.8 liters/min), respectively. M. luteus demonstrated less damage than P. fluorescens, suggesting the hardy nature of the gram-positive strain versus that of the gram-negative microorganism. Comparison of results from the agar slide and Andersen impactors at the same sampling velocity showed that recovery and injury due to collection depends not only on the magnitude of the impaction velocity but also on the degree to which the microorganisms may be embedded in the collection medium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7747946

  9. Altered proportions of RCS-rat eyes.

    PubMed

    Schreckenberger, M; Eichhorn, M; Gottanka, J; Döbig, C; Lütjen-Drecoll, E

    1994-10-01

    The growth pattern of RCS-rat eyes with hereditary retinal degeneration was analysed morphometrically, evaluating midsagittal sections of the entire globe and sections of the chamber angle region. No changes of the axial diameter of RCS-rat eyes were found if compared with eyes of age-matched controls. There were, however, characteristic proportional changes in the anterior eye segment of RCS rats. The distance between the peripheral end of Descemet's membrane (DM) and both the posterior end of Schlemm's canal and the ora serrata were significantly elongated indicating that this region might be most susceptible to growth factors. The length of the posterior globe up to the level of the ora serrata was shorter in RCS rats than in control rats. In addition, in RCS-rat eyes the pars plana was significantly elongated and the pars plicata shortened. Ultrastructural changes of ciliary epithelium were not seen before 7 months of age in RCS rats. They were only present in those parts of the circumference in which the stromal capillaries also revealed structural changes. The ciliary epithelial alterations were therefore considered secondary to narrowing or rarefication in the adjacent blood vessels.

  10. [Laboratory-based evaluation of a selective X-SA agar medium supplemented with chromogenic substrate for Staphylococcus aureus].

    PubMed

    Nakasone, Isamu; Yamane, Nobuhisa

    2005-01-01

    The newly developed culture medium, X-SA agar medium (Nissui Pharmaceuticals Co., Ltd., Tokyo) selective for Staphylococcus aureus was evaluated for its ability to detect clinical isolates of S. aureus. Besides S. aureus, X-SA agar media allowed the growth of coagulase-negative staphylococci, Bacillus cereus and some isolates of corynebacteria. However, those species were easily distinguishable from the blue and convex colonies of S. aureus. When compared to the traditional egg yolk mannitol salt agar, selectivity for the species other than S. aureus was more specific, and growth support for S. aureus was more comparable to sheep blood agar. Also, when various phenotypic variants of S. aureus were inoculated, visible colonies of mucoid colony variants and attenuated growth variants on Mueller-Hinton agar appeared on X-SA agar plates after 24 hour-incubation, but it required 48 hour-incubation for small colony variants. The fully automated microbiology system, RAISUS (Nissui Pharmaceuticals Co., Ltd.) gave comparable species-identification and antimicrobial susceptibility test results when cell suspension directly prepared from X-SA agar media was tested. However, species-identification for phenotypic variants of S. aureus was more complicated for RAISUS testing and detection of coagulase. With these results, it could be concluded that the X-SA agar medium supplemented with chromogenic substrate is superior to the traditional selective media for the detection of S. aureus, and is widely applicable for clinical microbiology as well as food microbiology.

  11. Use of prawn blood agar hemolysis to screen for bacteria pathogenic to cultured tiger prawns Penaeus monodon.

    PubMed

    Chang, C I; Liu, W Y; Shyu, C Z

    2000-11-14

    A newly developed prawn blood agar consisting of 1 ml of tiger prawn hemolymph in medium containing 200 ppm Rose Bengal was used to determine the hemolytic activity of 35 isolates of bacteria obtained from cultured tiger prawns Penaeus monodon and their rearing water. For comparison, the hemolytic activity of these isolates was also determined in sheep blood agar. Nine isolates (25.7% of total) showed different hemolytic reactions on prawn blood agar and sheep blood agar. From the 35 isolates, 8 with various hemolytic characteristics were selected and the relationship between the type of hemolytic activity and pathogenicity was determined and compared. Four isolates that showed hemolytic activity in prawn blood agar caused high mortality to cultured tiger prawns. By contrast, a significantly lower mortality rate was observed for tiger prawns injected with 4 isolates that did not exhibit hemolytic activity on prawn blood agar. Results further showed that mortality did not correlate with hemolytic activity determined using sheep blood agar. Prawn blood agar containing P. monodon hemocytes was faster and more accurate for determining prawn hemolytic activity of bacterial isolates.

  12. Effect of lignin on water vapor barrier, mechanical, and structural properties of agar/lignin composite films.

    PubMed

    Shankar, Shiv; Reddy, Jeevan Prasad; Rhim, Jong-Whan

    2015-11-01

    Biodegradable composite films were prepared using two renewable resources based biopolymers, agar and lignin alkali. The lignin was used as a reinforcing material and agar as a biopolymer matrix. The effect of lignin concentration (1, 3, 5, and 10wt%) on the performance of the composite films was studied. In addition, the mechanical, water vapor barrier, UV light barrier properties, FE-SEM, and TGA of the films were analyzed. The agar/lignin films exhibited higher mechanical and UV barrier properties along with lower water vapor permeability compared to the neat agar film. The FTIR and SEM results showed the compatibility of lignin with agar polymer. The swelling ratio and moisture content of agar/lignin composite films were decreased with increase in lignin content. The thermostability and char content of agar/lignin composite films increased with increased lignin content. The results suggested that agar/lignin films have a potential to be used as a UV barrier food packaging material for maintaining food safety and extending the shelf-life of the packaged food.

  13. Use of prawn blood agar hemolysis to screen for bacteria pathogenic to cultured tiger prawns Penaeus monodon.

    PubMed

    Chang, C I; Liu, W Y; Shyu, C Z

    2000-11-14

    A newly developed prawn blood agar consisting of 1 ml of tiger prawn hemolymph in medium containing 200 ppm Rose Bengal was used to determine the hemolytic activity of 35 isolates of bacteria obtained from cultured tiger prawns Penaeus monodon and their rearing water. For comparison, the hemolytic activity of these isolates was also determined in sheep blood agar. Nine isolates (25.7% of total) showed different hemolytic reactions on prawn blood agar and sheep blood agar. From the 35 isolates, 8 with various hemolytic characteristics were selected and the relationship between the type of hemolytic activity and pathogenicity was determined and compared. Four isolates that showed hemolytic activity in prawn blood agar caused high mortality to cultured tiger prawns. By contrast, a significantly lower mortality rate was observed for tiger prawns injected with 4 isolates that did not exhibit hemolytic activity on prawn blood agar. Results further showed that mortality did not correlate with hemolytic activity determined using sheep blood agar. Prawn blood agar containing P. monodon hemocytes was faster and more accurate for determining prawn hemolytic activity of bacterial isolates. PMID:11145455

  14. Performance of chromID Clostridium difficile agar compared with BBL C. difficile selective agar for detection of C. difficile in stool specimens.

    PubMed

    Han, Sang Bong; Chang, Jiyoung; Shin, Sang Hyun; Park, Kang Gyun; Lee, Gun Dong; Park, Yong Gyu; Park, Yeon-Joon

    2014-09-01

    We evaluated the performance of a new chromogenic medium for detection of Clostridium difficile, chromID C. difficile agar (CDIF; bioMérieux, France), by comparison with BBL C. difficile Selective Agar (CDSA; Becton Dickinson and Company, USA). After heat pre-treatment (80℃, 5 min), 185 diarrheal stool samples were inoculated onto the two media types and incubated anaerobically for 24 hr and 48 hr for CDIF and for 48 hr and 72 hr for CDSA. All typical colonies on each medium were examined by Gram staining, and the gram-positive rods confirmed to contain the tpi gene by PCR were identified as C. difficile. C. difficile was recovered from 36 samples by using a combination of the two media. The sensitivity with CDIF 48 hr was highest (100%) and was significantly higher than that with CDIF 24 hr (58.3%; P<0.001), because samples with a low burden of C. difficile tended to require prolonged incubation up to 48 hr (P<0.001). The specificity of CDIF 24 hr and CDIF 48 hr (99.3% and 90.6%, respectively) was significantly higher than that of CDSA 48 hr and CDSA 72 hr (72.5% and 67.1%, respectively; P<0.001). CDIF was effective for detecting C. difficile in heat-pretreated stool specimens, thus reducing unnecessary testing for toxin production in non-C. difficile isolates and turnaround time.

  15. Enhanced degradation of phenol by Pseudomonas sp. CP4 entrapped in agar and calcium alginate beads in batch and continuous processes.

    PubMed

    Aneez Ahamad, P Y; Mohammad Kunhi, A A

    2011-04-01

    Phenol is one of the major toxic pollutants in the wastes generated by a number of industries and needs to be eliminated before their discharge. Although microbial degradation is a preferred method of waste treatment for phenol removal, the general inability of the degrading strains to tolerate higher substrate concentrations has been a bottleneck. Immobilization of the microorganism in suitable matrices has been shown to circumvent this problem to some extent. In this study, cells of Pseudomonas sp. CP4, a laboratory isolate that degrades phenol, cresols, and other aromatics, were immobilized by entrapment in Ca-alginate and agar gel beads, separately and their performance in a fluidized bed bioreactor was compared. In batch runs, with an aeration rate of 1 vol(-1) vol(-1) min(-1), at 30°C and pH 7.0 ± 0.2, agar-encapsulated cells degraded up to 3000 mg l(-1) of phenol as compared to 1500 mg l(-1) by Ca-alginate-entrapped cells whereas free cells could tolerate only 1000 mg l(-1). In a continuous process with Ca-alginate entrapped cells a degradation rate of 200 mg phenol l(-1) h(-1) was obtained while agar-entrapped cells were far superior and could withstand and degrade up to 4000 mg phenol l(-1) in the feed with a maximum degradation rate of 400 mg phenol l(-1) h(-1). The results indicate a clear possibility of development of an efficient treatment technology for phenol containing waste waters with the agar-entrapped bacterial strain, Pseudomonas sp. CP4.

  16. A modified MacConkey agar for selective enumeration of necrotoxigenic E. coli O55 and probiotic E. coli Nissle 1917.

    PubMed

    Splichalova, Alla; Splichal, Igor; Sonnenborn, Ulrich; Rada, Vojtech

    2014-09-01

    An agar selective enumeration of necrotoxigenic Escherichia coli O55 (NTEC2) and probiotic E. coli Nissle 1917, using modified MacConkey agar, was developed to study bacterial interference between these E. coli strains in a gnotobiotic piglet model. Replacement of lactose with saccharose in the agar enables the direct visual enumeration of red colonies of E. coli O55 and yellow colonies of E. coli Nissle 1917 that are co-cultured in the same Petri dish. A total of 336 colonies (168 for each color) were subjected to strain-specific PCR identification with LNA probes. Sensitivity, specificity, and positive and negative predictive values were 96.43%, 95.83%, 95.86% and 96.41% respectively in E. coli O55, and 98.21%, 97.02%, 97.06% and 98.19% respectively in E. coli Nissle 1917. Color-based enumeration of both E. coli strains in colonic contents and mesenteric lymph nodes homogenates of gnotobiotic piglets demonstrated the applicability of this method for the gnotobiotic piglet model of enteric diseases. PMID:25008462

  17. A modified MacConkey agar for selective enumeration of necrotoxigenic E. coli O55 and probiotic E. coli Nissle 1917.

    PubMed

    Splichalova, Alla; Splichal, Igor; Sonnenborn, Ulrich; Rada, Vojtech

    2014-09-01

    An agar selective enumeration of necrotoxigenic Escherichia coli O55 (NTEC2) and probiotic E. coli Nissle 1917, using modified MacConkey agar, was developed to study bacterial interference between these E. coli strains in a gnotobiotic piglet model. Replacement of lactose with saccharose in the agar enables the direct visual enumeration of red colonies of E. coli O55 and yellow colonies of E. coli Nissle 1917 that are co-cultured in the same Petri dish. A total of 336 colonies (168 for each color) were subjected to strain-specific PCR identification with LNA probes. Sensitivity, specificity, and positive and negative predictive values were 96.43%, 95.83%, 95.86% and 96.41% respectively in E. coli O55, and 98.21%, 97.02%, 97.06% and 98.19% respectively in E. coli Nissle 1917. Color-based enumeration of both E. coli strains in colonic contents and mesenteric lymph nodes homogenates of gnotobiotic piglets demonstrated the applicability of this method for the gnotobiotic piglet model of enteric diseases.

  18. Root architecture and morphometric analysis of Arabidopsis thaliana grown in Cd/Cu/Zn-gradient agar dishes: A new screening technique for studying plant response to metals.

    PubMed

    Bochicchio, Rocco; Sofo, Adriano; Terzano, Roberto; Gattullo, Concetta Eliana; Amato, Mariana; Scopa, Antonio

    2015-06-01

    A new screening strategy using Petri dishes with a gradient of distances between germinating seeds and a metal-contaminated medium was used for studying alterations in root architecture and morphology of Arabidopsis thaliana treated with cadmium, copper and zinc at sub-toxic concentrations. Metal concentrations in the dishes were determined by anodic stripping voltammetry on digested agar samples collected along the gradient, and kriging statistical interpolation method was performed. After two weeks, all agar dishes were scanned at high resolution and the root systems analyzed. In the presence of all the three metals, primary root length did not significantly change compared to controls, excepting for zinc applied alone (+45% of controls). In metal-treated seedlings, root system total length increased due to the higher number of lateral roots. The seedlings closer to the agar sectors including metals showed a marked curvature and a higher root branching in comparison to those further away from the metals. This behavior, together with an observed increase in root diameter in metal-treated seedlings could be interpreted as compensatory growth, and a thicker roots could act as a barrier to protect root from the metals. We therefore propose that the remodeling of the root architecture in response to metals could be a pollution 'escaping strategy' aimed at seeking metal-free patches.

  19. Proportional counting techniques for routine tritium analyses at environmental levels

    SciTech Connect

    Bowman, W W; Hughes, M B

    1981-01-01

    Techniques and procedures were developed to routinely analyze samples for tritium as part of research and monitoring programs on the transport of radionuclides released from the Savannah River Plant site. Because tritium concentrations in the environment are low, trace analysis methods were developed. The primary analysis technique involves converting aqueous samples to hydrogen gas which is mixed with propane and assayed in proportional counters. Counter background is reduced by massive shielding, anticoincidence gating with plastic scintillators, and pulse shape discrimination. The overall sensitivity for tritium is 0.02 pCi/g of water with a demonstrated precision of 6.3% at 1 pCi/g of water.

  20. GSFC's Multi-Wire Gas Proportional Counter

    NASA Astrophysics Data System (ADS)

    Serlemitsos, Peter J.

    2013-01-01

    The Goddard X-ray group made its appearance in 1964 as a one person (Elihu Boldt) appendage to the well established cosmic ray group, then headed by Frank MacDonald. This discipline proximity was crucial because it meant superb technical support from the start, which allowed the fledging group to quickly advance toward directions of choice. When I became the 2nd member of the group in 1966, the new discipline still relied on bulky gas counters, stacked to make up a usable detection area. Slim opportunities existed for timing or spectral inferences. Elihu's strong interest in pursuing the reported diffuse cosmic radiation had to be set aside, as improving this situation appeared to be years away. Cosmic ray researchers had long used charged particle timing techniques for cleaning up their data, but those appeared irrelevant for our purposes because of the large, background generating, mass of the gas containment vessels and the slow drift in the counter gas of the charge from photon interaction sites to the counter anode. We had to deal with these realities in whatever choices we made for our future instruments. The multi-wire gas proportional counter emerged from our still small group in the late1960s, demonstrating on several rocket and balloon flights a greatly reduced detector background, improved event timing and adequate resolution for addressing key spectral features. Three of these detectors, flown in 1975 on NASA's 8th orbiting solar observatory, were successfully used for some 3 years to conduct non dispersive, 1-10 keV spectroscopy on many galactic and extragalactic sources, including several clusters of galaxies. In 1977 we flew a set of larger detectors on the first of NASA's High Energy Astrophysical Observatories (HEAO). These were specifically designed for the study of the X-ray background. Finally, the largest instruments of this family were flown in 1995 by our group on NASA's Rossi X-ray Timing Explorer, RXTE, which observed over a remarkable 16

  1. Evaluation of a new selective chromogenic agar medium for detection of extended-spectrum beta-lactamase-producing Enterobacteriaceae.

    PubMed

    Glupczynski, Youri; Berhin, Catherine; Bauraing, Caroline; Bogaerts, Pierre

    2007-02-01

    A novel chromogenic agar medium (ESBL-Bx; bioMérieux, Marcy l'Etoile, France) was compared to MacConkey agar supplemented with 2 mg ceftazidime/liter (MCKC) for the selective isolation and presumptive identification of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae directly from clinical samples. Of a total of 644 clinical specimens (including 551 fecal samples), 496 yielded no growth and 148 yielded growth on one or both media. Overall, 44 ESBL-producing Enterobacteriaceae strains (Escherichia coli [n=17], Enterobacter aerogenes [n=17], Klebsiella spp. [n=5], and Citrobacter freundii [n=5]) were isolated from 37 specimens by a combination of both methods after 18 to 24 h of incubation. The sensitivities were 97.7 and 84.1% for ESBL-Bx and MCKC, respectively, with 43 ESBL-positive strains isolated as colored colonies from 36 specimens on ESBL-Bx versus 37 ESBL-positive organisms isolated from 32 specimens on MCKC. The specificities by specimens were 89 and 91% for ESBL-Bx and MCKC, respectively. On either one of the two media, natural AmpC-hyperproducing Enterobacter spp. (n=25) and Citrobacter spp. (n=14) were the most common false positives as well as non-ESBL-producing Klebsiella oxytoca (n=18) on ESBL-Bx and Morganella morganii (n=10) on MCKC. We conclude that ESBL-Bx is a sensitive and specific medium for the isolation of ESBL-producing Enterobacteriaceae from clinical samples. The main advantages of ESBL-Bx over MCKC reside in its chromogenic character and its sensitivity and selectivity, which enabled the recovery and presumptive identification of most ESBL-producing Enterobacteriaceae within 24 h and reduced by 27% the need for unnecessary identification and confirmation of ESBL testing when disregarding all colorless colonies growing on this medium.

  2. Adjusted Wald Confidence Interval for a Difference of Binomial Proportions Based on Paired Data

    ERIC Educational Resources Information Center

    Bonett, Douglas G.; Price, Robert M.

    2012-01-01

    Adjusted Wald intervals for binomial proportions in one-sample and two-sample designs have been shown to perform about as well as the best available methods. The adjusted Wald intervals are easy to compute and have been incorporated into introductory statistics courses. An adjusted Wald interval for paired binomial proportions is proposed here and…

  3. Characterization of gelatin-agar based phase separated hydrogel, emulgel and bigel: a comparative study.

    PubMed

    Wakhet, Senggam; Singh, Vinay K; Sahoo, Saikat; Sagiri, Sai Sateesh; Kulanthaivel, Senthilguru; Bhattacharya, Mrinal K; Kumar, Naresh; Banerjee, Indranil; Pal, Kunal

    2015-02-01

    The current study describes the in-depth characterization of agar-gelatin based co-hydrogels, emulgels and bigels to have an insight about the differences in the properties of the formulations. Hydrogels have been extensively studied as vehicle for controlled drug release, whereas, the concept of emulgels and bigels is relatively new. The formulations were characterized by scanning electron microscopy, FTIR spectroscopy, XRD and mechanical properties. The biocompatibility and the ability of the formulations to be used as drug delivery vehicle were also studied. The scanning electron micrographs suggested the presence of internal phases within the agar-gelatin composite matrices of co-hydrogel, emulgel and bigel. FTIR and XRD studies suggested higher crystallinity of emulgels and bigels. Electrical impedance and mechanical stability of the emulgel and the bigel was higher than the hydrogel. The prepared formulations were found to be biocompatible and suitable for drug delivery applications.

  4. Effect of Soybean Casein Digest Agar Lot on Number of Bacillus stearothermophilus Spores Recovered †

    PubMed Central

    Pflug, I. J.; Smith, Geraldine M.; Christensen, Ronald

    1981-01-01

    In recent years it has become increasingly apparent that Bacillus stearothermophilus spores are affected by various environmental factors that influence the performance of the spores as biological indicators. One environmental factor is the recovery medium. The effect of different lots of commercial soybean casein digest agar on the number of colony-forming units per plate was examined in two series of experiments: (i) several lots of medium from two manufacturers were compared in single experiments, and (ii) paired media experiments with four lots of medium were carried out and yielded three-point survivor curves. The results demonstrate that commercial soybean casein digest agar is variable on a lot-to-lot basis. The variation was lowest when recovering unheated or minimally heated spores and increased greatly with the severity of heating. PMID:16345822

  5. Rapid Isolation and Susceptibility Testing of Leptospira spp. Using a New Solid Medium, LVW Agar

    PubMed Central

    Wuthiekanun, Vanaporn; Amornchai, Premjit; Paris, Daniel H.; Langla, Sayan; Thaipadunpanit, Janjira; Chierakul, Wirongrong; Smythe, Lee D.; White, Nicholas J.; Day, Nicholas P. J.; Peacock, Sharon J.

    2013-01-01

    Pathogenic Leptospira spp., the causative agents of leptospirosis, are slow-growing Gram-negative spirochetes. Isolation of Leptospira from clinical samples and testing of antimicrobial susceptibility are difficult and time-consuming. Here, we describe the development of a new solid medium that facilitates more-rapid growth of Leptospira spp. and the use of this medium to evaluate the Etest's performance in determining antimicrobial MICs to drugs in common use for leptospirosis. The medium was developed by evaluating the effects of numerous factors on the growth rate of Leptospira interrogans strain NR-20157. These included the type of base agar, the concentration of rabbit serum (RS), and the concentration and duration of CO2 incubation during the initial period of culture. The highest growth rate of NR-20157 was achieved using a Noble agar base supplemented with 10% RS (named LVW agar), with an initial incubation at 30°C in 5% CO2 for 2 days prior to continuous culture in air at 30°C. These conditions were used to develop the Etest for three species, L. interrogans (NR-20161), L. kirschnerii (NR-20327), and L. borgpetersenii (NR-20151). The MICs were read on day 7 for all samples. The Etest was then performed on 109 isolates of pathogenic Leptospira spp. The MIC90 values for penicillin G, doxycycline, cefotaxime, ceftriaxone, and chloramphenicol were 0.64 units/ml and 0.19, 0.047, 0.5, and 2 μg/ml, respectively. The use of LVW agar, which enables rapid growth, isolation of single colonies, and simple antimicrobial susceptibility testing for Leptospira spp., provides an opportunity for new areas of fundamental and applied research. PMID:23114772

  6. The arcsine is asinine: the analysis of proportions in ecology.

    PubMed

    Warton, David I; Hui, Francis K C

    2011-01-01

    The arcsine square root transformation has long been standard procedure when analyzing proportional data in ecology, with applications in data sets containing binomial and non-binomial response variables. Here, we argue that the arcsine transform should not be used in either circumstance. For binomial data, logistic regression has greater interpretability and higher power than analyses of transformed data. However, it is important to check the data for additional unexplained variation, i.e., overdispersion, and to account for it via the inclusion of random effects in the model if found. For non-binomial data, the arcsine transform is undesirable on the grounds of interpretability, and because it can produce nonsensical predictions. The logit transformation is proposed as an alternative approach to address these issues. Examples are presented in both cases to illustrate these advantages, comparing various methods of analyzing proportions including untransformed, arcsine- and logit-transformed linear models and logistic regression (with or without random effects). Simulations demonstrate that logistic regression usually provides a gain in power over other methods.

  7. N-acetylgalatosamine-Mediated Regulation of the aga Operon by AgaR in Streptococcus pneumoniae

    PubMed Central

    Afzal, Muhammad; Shafeeq, Sulman; Ahmed, Hifza; Kuipers, Oscar P.

    2016-01-01

    Here, we analyze the transcriptomic response of Streptococcus pneumoniae D39 to N-acetylgalactosamine (NAGa). Transcriptome comparison of S. pneumoniae D39 grown in NAGaM17 (0.5% NAGa + M17) to that grown in GM17 (0.5% Glucose + M17) revealed the elevated expression of various carbon metabolic genes/operons, including a PTS operon (denoted here as the aga operon), which is putatively involved in NAGa transport and utilization, in the presence of NAGa. We further studied the role of a GntR-family transcriptional regulator (denoted here as AgaR) in the regulation of aga operon. Our transcriptome and RT-PCR data suggest the role of AgaR as a transcriptional repressor of the aga operon. We predicted a 20-bp operator site of AagR (5′-ATAATTAATATAACAACAAA-3′) in the promoter region of the aga operon (PbgaC), which was further verified by mutating the AgaR operator site in the respective promoter. The role of CcpA in the additional regulation of the aga operon was elucidated by further transcriptome analyses and confirmed by quantitative RT-PCR.

  8. A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

    PubMed Central

    Sanders, Lisa; Andermann, Tessa M.

    2013-01-01

    Directed motility, or chemotaxis, is required for Helicobacter pylori to establish infection in the stomach, although the full repertoire of this bacterium’s chemotactic responses is not yet known. Here we report that H. pylori responds to zinc as an attractant and nickel as a repellent. To reach this conclusion, we employed both a temporal chemotaxis assay based on bacterial reversals and a supplemented soft agar spatial assay. We refined the temporal assay using a previously described chemorepellent, acid, and found that H. pylori requires rich media with serum to maintain optimal swimming motility. Surprisingly, we found that some strains respond to acid as an attractant, and that the TlpC chemoreceptor correlated with whether acid was sensed as an attractant or repellent. Using this same assay, we detected weak repellent responses to nickel and copper, and a varied response to zinc. We thus developed an alternative spatial chemotactic assay called the supplemented soft agar assay, which utilizes soft agar medium supplemented with the test compound. With Escherichia coli, the attractant serine slowed overall bacterial migration, while the repellent nickel increased the speed of overall migration. In H. pylori we detected slowed migration with doubled tryptone media, as well as zinc, consistent with an attractant response. In contrast, nickel increased migration, consistent with repulsion. PMID:23139399

  9. Alternative plasticizers for the production of thermo-compressed agar films.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Liu, LinShu; Gonçalves, Maria P

    2015-05-01

    Agar films were produced by thermo-compression using choline chloride (ChCl) as a plasticizer with urea. The three solid components were mixed together with the salt and urea (minor components) added to agar (main component) according to a fixed mass ratio of, respectively, 1.16:1:5. A central composite rotatable design (CCRD) with three parameters, 2(3), was used to evaluate the effects of temperature (X1; °C), time (X2; min) and applied load (X3; kN) of heat-pressing on the maximum tensile strength (TS) of the films (Y; MPa). Mixtures of urea and agar prepared at a mass ratio of 1:5 did not form homogeneous films suggesting the important plasticizing role of the salt. Heat-pressing the mixtures at more draconian conditions led to much darker and opaque films, with better mechanical resistance (higher values of TS). The most resistant film (∼ 15 MPa) was obtained at 140°C, 20 min and 176 kN. Selected films, including the optimal, showed similar water sorption profiles and close values of water vapor permeability (∼ 2.5-3.7 × 10(-9)gm(-1)s(-1)Pa(-1)). The fracture behavior and mechanical properties of the films were greatly affected by additional water plasticization when the films were stored at different conditions of relative humidity. PMID:25727746

  10. Application of solid-phase extraction to agar-supported fermentation.

    PubMed

    Le Goff, Géraldine; Adelin, Emilie; Cortial, Sylvie; Servy, Claudine; Ouazzani, Jamal

    2013-09-01

    Agar-supported fermentation (Ag-SF), a variant of solid-state fermentation, has recently been improved by the development of a dedicated 2 m(2) scale pilot facility, Platotex. We investigated the application of solid-phase extraction (SPE) to Ag-SF in order to increase yields and minimize the contamination of the extracts with agar constituents. The selection of the appropriate resin was conducted on liquid-state fermentation and Diaion HP-20 exhibited the highest recovery yield and selectivity for the metabolites of the model fungal strains Phomopsis sp. and Fusarium sp. SPE applied to Ag-SF resulted in a particular compartmentalization of the culture. The mycelium that requires oxygen to grow migrates to the top layer and formed a thick biofilm. The resin beads intercalate between the agar surface and the mycelium layer, and trap directly the compounds secreted by the mycelium through a "solid-solid extraction" (SSE) process. The resin/mycelium layer is easily recovered by scraping the surface and the target metabolites extracted by methanol. Ag-SF associated to SSE represents an ideal compromise for the production of bioactive secondary metabolites with limited economic and environmental impact.

  11. N-acetylgalatosamine-Mediated Regulation of the aga Operon by AgaR in Streptococcus pneumoniae

    PubMed Central

    Afzal, Muhammad; Shafeeq, Sulman; Ahmed, Hifza; Kuipers, Oscar P.

    2016-01-01

    Here, we analyze the transcriptomic response of Streptococcus pneumoniae D39 to N-acetylgalactosamine (NAGa). Transcriptome comparison of S. pneumoniae D39 grown in NAGaM17 (0.5% NAGa + M17) to that grown in GM17 (0.5% Glucose + M17) revealed the elevated expression of various carbon metabolic genes/operons, including a PTS operon (denoted here as the aga operon), which is putatively involved in NAGa transport and utilization, in the presence of NAGa. We further studied the role of a GntR-family transcriptional regulator (denoted here as AgaR) in the regulation of aga operon. Our transcriptome and RT-PCR data suggest the role of AgaR as a transcriptional repressor of the aga operon. We predicted a 20-bp operator site of AagR (5′-ATAATTAATATAACAACAAA-3′) in the promoter region of the aga operon (PbgaC), which was further verified by mutating the AgaR operator site in the respective promoter. The role of CcpA in the additional regulation of the aga operon was elucidated by further transcriptome analyses and confirmed by quantitative RT-PCR. PMID:27672623

  12. Pig and Goat Blood as Substitutes for Sheep Blood in Blood-Supplemented Agar Media

    PubMed Central

    Anand, Chandar; Gordon, Rhonda; Shaw, Helene; Fonseca, Kevin; Olsen, Merle

    2000-01-01

    In many developing countries sheep and horse blood, the recommended blood supplements in bacteriological media, are not readily available, whereas pig and goat blood are. Therefore, this study examined the use of pig and goat blood as potential substitutes for sheep blood in blood-supplemented bacteriologic media commonly used in clinical microbiology laboratories. In general, the growth characteristics and colony morphologies of a wide range of aerobic and anaerobic bacteria and Candida albicans were similar on media containing pig, goat, and sheep blood, although differences were found. Enterococcus sp. uniformly produced alpha-hemolysis when incubated in CO2, but in anaerobic conditions the hemolysis varied. In contrast, beta-hemolytic streptococci produced identical hemolytic reactions on all three media. Synergistic hemolysis was not observed on pig blood agar in the CAMP test nor on goat blood agar in the reverse CAMP test. The preparation of chocolate agar (heated) with pig blood required heating to a higher temperature than with sheep or goat blood to yield suitable growth of Haemophilus species. In general, we conclude that pig and goat blood are suitable alternatives to sheep blood for use in bacteriological media in settings where sheep and horse blood are not readily available. PMID:10655351

  13. New agar microspheres for the separation and purification of natural products.

    PubMed

    Ge, Chunling; Hu, Yu; Zhang, Fan; Lv, Yongqin; Tan, Tianwei

    2014-11-01

    A new type of agar chromatography media has been prepared with a yield over 80% using a water-in-oil emulsion technique. These microspheres have regular spherical shapes and particle diameters in the range 40-165 μm (average ∼90 μm). Cross-linking of the resulting agar microspheres with epichlorohydrin and 1,4-butanediol diglycidyl ether enhanced their mechanical and thermal stability. The alkaline conditions used during the cross-linking reaction also decreased the content of ionized sulfate groups of the polysaccharide, thus reducing the nonspecific adsorption of positively charged molecules. The cross-linked agar microspheres were functionalized with (i) branched poly(ethyleneimine) to obtain a stationary phase useful for the separation of proteins in an anion-exchange mode and (ii) with poly-β-cyclodextrin enabling direct isolation and purification of puerarin from a crude extract of Radix puerariae. Using a 23.5 mL column loaded with 20 mg extract (0.85 mg/mL gel), puerarin with a purity of 96% was recovered with a yield of 86%.

  14. Evaluation of cephamycins as supplements to selective agar for detecting Campylobacter spp. in chicken carcass rinses.

    PubMed

    Chon, Jung-Whan; Kim, Young-Ji; Kim, Hong-Seok; Kim, Dong-Hyeon; Kim, Hyunsook; Song, Kwang-Young; Sung, Kidon; Seo, Kun-Ho

    2016-04-16

    Although cefoperazone is the most commonly used antibiotic in Campylobacter-selective media, the distribution of cefoperazone-resistant bacteria such as extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is increasing. Here we evaluated the potential of cephamycins for use as supplements to improve modified charcoal-cefoperazone-deoxycholate agar (mCCDA) by replacing cefoperazone with the same concentrations (32 mg/L) of cefotetan (modified charcoal-cefotetan-deoxycholate agar, mCCtDA) and cefoxitin (modified charcoal-cefoxitin-deoxycholate agar, mCCxDA). In chicken carcass rinse samples, the number of mCCDA plates detecting for Campylobacter (18/70, 26%) was significantly lower than that of mCCtDA (42/70, 60%) or mCCxDA plates (40/70, 57%). The number of mCCDA plates (70/70, 100%) that were contaminated with non-Campylobacter species was significantly higher than that of mCCtDA (20/70, 29%) or mCCxDA plates (21/70, 30%). The most common competing species identified using mCCDA was ESBL-producing E. coli, while Pseudomonas species frequently appeared on mCCtDA and mCCxDA.

  15. Evaluation of Petrifilm™ aerobic count plates as an equivalent alternative to drop plating on R2A agar plates in a biofilm disinfectant efficacy test.

    PubMed

    Fritz, B G; Walker, D K; Goveia, D E; Parker, A E; Goeres, D M

    2015-03-01

    This paper compares Petrifilm™ aerobic count (AC) plates to drop plating on R2A agar plates as an alternative method for biofilm bacteria enumeration after application of a disinfectant. A Pseudomonas aeruginosa biofilm was grown in a Centers for Disease Control and Prevention biofilm reactor (ASTM E2562) and treated with 123 ppm sodium hypochlorite (as free chlorine) according to the Single Tube Method (ASTM E2871). Aliquots from the same dilution tubes were plated on Petrifilm™ AC plates and drop plated on R2A agar plates. The Petrifilm™ AC and R2A plates were incubated for 48 and 24 h, respectively, at 36 ± 1 °C. After nine experimental runs performed by two technicians, the mean difference in biofilm log densities [log biofilm density (LD) = log10(CFU/cm(2))] between the two methods for control coupons, treated coupons, and log reduction (LR) was 0.052 (p = 0.451), -0.102 (p = 0.303), and 0.152 (p = 0.313). Equivalence testing was used to assess equivalence of the two plating methods. The 90 % confidence intervals for the difference in control and treated mean LDs between methods were (-0.065, 0.170) and (-0.270, 0.064), both of which fall within a (-0.5, +0.5) equivalence criterion. The 90 % confidence interval for the mean LR difference (-0.113, 0.420) also falls within this equivalence criterion. Thus, Petrifilm™ AC plates were shown to be statistically equivalent to drop plating on R2A agar for the determination of control LDs, treated LDs, and LR values in an anti-biofilm efficacy test. These are the first published results that establish equivalency to a traditional plate counting technique for biofilms and for a disinfectant assay.

  16. Isolation of Clostridium difficile from faecal specimens--a comparison of chromID C. difficile agar and cycloserine-cefoxitin-fructose agar.

    PubMed

    Carson, Kerry C; Boseiwaqa, Lusiana V; Thean, Sara K; Foster, Niki F; Riley, Thomas V

    2013-09-01

    The culture of toxigenic Clostridium difficile from stool specimens is still seen as the gold standard for the laboratory diagnosis of C. difficile infection (CDI). bioMérieux have released ChromID Cdiff chromogenic agar (CDIF) for the isolation and identification of C. difficile in 24 h. In this study, we compared CDIF to pre-reduced cycloserine-cefoxitin-fructose agar with sodium taurocholate (TCCFA) in the examination of glutamate dehydrogenase-positive faecal specimens that were either GeneOhm positive or negative, using direct culture or culture following alcohol shock. Direct culture on CDIF had a sensitivity of 100 % and recovery of 94 % while for TCCFA these were 87 % and 82 %, respectively. For GeneOhm-positive alcohol-shocked faecal samples, sensitivity and recovery on CDIF was similar to direct culture while on TCCFA they were about 10 % higher. For direct culture, there was a significant difference between growth on CDIF at 24 h and TCCFA at 48 h (P = 0.001) and between the two media at 48 h (P<0.001). A total of 142 strains of C. difficile were recovered in pure culture from all GeneOhm-positive samples used in this study and 11 (7.7 %) of these were A(-)B(-)CDT(-) and may represent mixed infections of toxigenic and non-toxigenic C. difficile. The most dominant ribotype was UK 014 (14.7 %) followed by 002 (11.9 %) and 020 (11.9 %), and 36 % of toxigenic isolates, including an A(-)B(+)CDT(-) strain, could not be assigned a UK ribotype. CDIF outperformed pre-reduced TCCFA by negating the need for alcohol shock treatment and by giving a time saving of 24 h in the isolation of C. difficile. CDIF plates were also more selective than TCCFA and C. difficile colonies were easy to identify and subculture prior to strain typing.

  17. High proportion of male faeces in jaguar populations.

    PubMed

    Palomares, Francisco; Roques, Séverine; Chávez, Cuauhtémoc; Silveira, Leandro; Keller, Claudia; Sollmann, Rahel; do Prado, Denise Mello; Torres, Patricia Carignano; Adrados, Begoña; Godoy, José Antonio; de Almeida Jácomo, Anah Tereza; Tôrres, Natália Mundim; Furtado, Mariana Malzoni; López-Bao, José Vicente

    2012-01-01

    Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species.

  18. High proportion of male faeces in jaguar populations.

    PubMed

    Palomares, Francisco; Roques, Séverine; Chávez, Cuauhtémoc; Silveira, Leandro; Keller, Claudia; Sollmann, Rahel; do Prado, Denise Mello; Torres, Patricia Carignano; Adrados, Begoña; Godoy, José Antonio; de Almeida Jácomo, Anah Tereza; Tôrres, Natália Mundim; Furtado, Mariana Malzoni; López-Bao, José Vicente

    2012-01-01

    Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species. PMID:23285226

  19. High Proportion of Male Faeces in Jaguar Populations

    PubMed Central

    Palomares, Francisco; Roques, Séverine; Chávez, Cuauhtémoc; Silveira, Leandro; Keller, Claudia; Sollmann, Rahel; do Prado, Denise Mello; Torres, Patricia Carignano; Adrados, Begoña; Godoy, José Antonio; de Almeida Jácomo, Anah Tereza; Tôrres, Natália Mundim; Furtado, Mariana Malzoni; López-Bao, José Vicente

    2012-01-01

    Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species. PMID:23285226

  20. Optimization of simultaneous tritium-radiocarbon internal gas proportional counting

    NASA Astrophysics Data System (ADS)

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference.

  1. Estimating proportions of objects from multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Horwitz, H. M.; Lewis, J. T.; Pentland, A. P.

    1975-01-01

    Progress is reported in developing and testing methods of estimating, from multispectral scanner data, proportions of target classes in a scene when there are a significiant number of boundary pixels. Procedures were developed to exploit: (1) prior information concerning the number of object classes normally occurring in a pixel, and (2) spectral information extracted from signals of adjoining pixels. Two algorithms, LIMMIX and nine-point mixtures, are described along with supporting processing techniques. An important by-product of the procedures, in contrast to the previous method, is that they are often appropriate when the number of spectral bands is small. Preliminary tests on LANDSAT data sets, where target classes were (1) lakes and ponds, and (2) agricultural crops were encouraging.

  2. Mathematically modelling proportions of Japanese populations by industry

    NASA Astrophysics Data System (ADS)

    Hirata, Yoshito

    2016-10-01

    I propose a mathematical model for temporal changes of proportions for industrial sectors. I prove that the model keeps the proportions for the primary, the secondary, and the tertiary sectors between 0 and 100% and preserves their total as 100%. The model fits the Japanese historical data between 1950 and 2005 for the population proportions by industry very well. The model also predicts that the proportion for the secondary industry becomes negligible and becomes less than 1% at least around 2080.

  3. A combined approach for the enhanced detection and isolation of Bartonella species in dog blood samples: pre-enrichment liquid culture followed by PCR and subculture onto agar plates.

    PubMed

    Duncan, Ashlee W; Maggi, Ricardo G; Breitschwerdt, Edward B

    2007-05-01

    Historically, direct plating, lysis centrifugation, or freeze-thaw approaches have proven to be highly insensitive methods for confirming Bartonella species infection in dogs. A prospective study was designed to compare diagnostic methods for the detection of Bartonella using samples submitted to the Vector-Borne Disease Diagnostic Laboratory at North Carolina State University. Methods included indirect immunofluorescence assay, PCR, direct inoculation of a blood agar plate (trypticase soy agar with 5% rabbit blood), and inoculation into a novel pre-enrichment liquid medium, Bartonella/alpha-Proteobacteria growth medium (BAPGM). Sequential research efforts resulted in the development of a combinational approach consisting of pre-enrichment culture of Bartonella species in BAPGM, sub-inoculation of the liquid culture onto agar plates, followed by DNA amplification using PCR. The multi-faceted approach resulted in substantial improvement in the microbiological detection and isolation of Bartonella when compared to direct inoculation of a blood agar plate. Importantly, this approach facilitated the detection and subsequent isolation of both single and co-infections with two Bartonella species in the blood of naturally infected dogs. The use of a combinational approach of pre-enrichment culture and PCR may assist in the diagnostic confirmation of bartonellosis in dogs and other animals.

  4. Optimizing stroke clinical trial design: estimating the proportion of eligible patients

    PubMed Central

    Taylor, Alexis; Castle, Amanda; Merino, José G.; Hsia, Amie; Kidwell, Chelsea S.; Warach, Steven

    2010-01-01

    Background and Purpose Clinical trial planning and site selection require an accurate estimate of the number of eligible patients at each site. In this study, we developed a tool to calculate the proportion of patients that would meet a specific trial's age, baseline severity and time to treatment inclusion criteria. Methods From a sample of 1322 consecutive patients with acute ischemic cerebrovascular syndromes, we developed regression curves relating the proportion of patients within each range of the three variables. We used half the patients to develop the model, and the other half to validate it by comparing predicted versus actual proportions that met the criteria for four current stroke trials. Results The predicted proportion of patients meeting inclusion criteria ranged from 6% to 28% among the different trials. The proportion of trial-eligible patients predicted from the first half of the data was within 0.4% to 1.4% of the actual proportion of eligible patients. This proportion increased logarithmically with NIHSS score and time from onset: lowering the baseline limits of the NIHSS score and the treatment window would have the greatest impact on the proportion of patients eligible for a stroke trial. Conclusions This model helps estimate the proportion of stroke patients eligible for a study based on different upper and lower limits for age, stroke severity and time to treatment, and may be a useful tool in clinical trial planning. PMID:20798375

  5. Evaluation of CHROMagar™ StrepB agar, an aerobic chromogenic medium for prepartum vaginal/rectal Group B Streptococcus screening.

    PubMed

    Poisson, Didier-Marc; Evrard, Marie-Liesse; Freneaux, Claire; Vivès, Marie-isabelle; Mesnard, Louis

    2011-03-01

    An aerobic chromogenic medium, CHROMagar™ StrepB agar, designed for isolation of group B Streptococci, was evaluated on 285 prepartum vaginal/rectal swabs from pregnant women. After overnight enrichment in Todd-Hewitt broth containing 15μg/ml nalidixic acid and 10μg/ml colistin, sensitivities were respectively 79% on day 1 and 92% on day 2, and significantly higher than those achieved by blood agar (40% and 58%) and colimycin-nalidixic-acid agar (82% on day 2).

  6. Spatial Proportional Reasoning Is Associated with Formal Knowledge about Fractions

    ERIC Educational Resources Information Center

    Möhring, Wenke; Newcombe, Nora S.; Levine, Susan C.; Frick, Andrea

    2016-01-01

    Proportional reasoning involves thinking about parts and wholes (i.e., about fractional quantities). Yet, research on proportional reasoning and fraction learning has proceeded separately. This study assessed proportional reasoning and formal fraction knowledge in 8- to 10-year-olds. Participants (N = 52) saw combinations of cherry juice and water…

  7. Sample size calculation for the proportional hazards cure model.

    PubMed

    Wang, Songfeng; Zhang, Jiajia; Lu, Wenbin

    2012-12-20

    In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial. PMID:22786805

  8. As-built design specification for proportion estimate software subsystem

    NASA Technical Reports Server (NTRS)

    Obrien, S. (Principal Investigator)

    1980-01-01

    The Proportion Estimate Processor evaluates four estimation techniques in order to get an improved estimate of the proportion of a scene that is planted in a selected crop. The four techniques to be evaluated were provided by the techniques development section and are: (1) random sampling; (2) proportional allocation, relative count estimate; (3) proportional allocation, Bayesian estimate; and (4) sequential Bayesian allocation. The user is given two options for computation of the estimated mean square error. These are referred to as the cluster calculation option and the segment calculation option. The software for the Proportion Estimate Processor is operational on the IBM 3031 computer.

  9. Students' Understanding of Proportional, Inverse Proportional, and Affine Functions: Two Studies on the Role of External Representations

    ERIC Educational Resources Information Center

    De Bock, Dirk; Van Dooren, Wim; Verschaffel, Lieven

    2015-01-01

    We investigated students' understanding of proportional, inverse proportional, and affine functions and the way this understanding is affected by various external representations. In a first study, we focus on students' ability to model textual descriptions of situations with different kinds of representations of proportional, inverse…

  10. The Identification and Validation Process of Proportional Reasoning Attributes: An Application of a Proportional Reasoning Modeling Framework

    ERIC Educational Resources Information Center

    Tjoe, Hartono; de la Torre, Jimmy

    2014-01-01

    In this paper, we discuss the process of identifying and validating students' abilities to think proportionally. More specifically, we describe the methodology we used to identify these proportional reasoning attributes, beginning with the selection and review of relevant literature on proportional reasoning. We then continue with the…

  11. Estimating sighting proportions of American alligator nests during helicopter survey

    USGS Publications Warehouse

    Rice, Kenneth G.; Percival, H. Franklin; Woodward, Allan R.

    2000-01-01

    Proportions of American alligator (Alligator mississippiensis) nests sighted during aerial survey in Florida were estimated based upon multiple surveys by different observers. We compared sighting proportions across habitats, nesting seasons, and observer experience levels. The mean sighting proportion across all habitats and years was 0.736 (SE=0.024). Survey counts corrected by the mean sighting proportion reliably predicted total nest counts (7?2=0.933). Sighting proportions did not differ by habitat type (P=0.668) or year P=0.328). Experienced observers detected a greater proportion of nests (P<0.0001) than did either less experienced or inexperienced observers. Reliable estimates of nest abundance can be derived from aerial counts of alligator nests when corrected by the appropriate sighting proportion.

  12. Comparison of agar dilution and antibiotic gradient strip test with broth microdilution for susceptibility testing of swine Brachyspira species.

    PubMed

    Mirajkar, Nandita S; Gebhart, Connie J

    2016-03-01

    Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics. PMID:26965233

  13. Multicenter Evaluation of MRSASelect II Chromogenic Agar for Identification of Methicillin-Resistant Staphylococcus aureus from Wound and Nasal Specimens

    PubMed Central

    Newton, Duane W.; Ledeboer, Nathan A.; Young, Carol; Clark, Andrew E.; Connoly, Jessica; Wolk, Donna M.

    2015-01-01

    Hospitals strive to reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence via active surveillance of inpatient populations. Rapid and inexpensive screening methods are utilized when molecular methods are not operationally feasible. In this multisite clinical trial, the utility of Bio-Rad's MRSASelect II was evaluated for MRSA identification from remnant nares and wound swabs. The prevalence of MRSA was 11.1% (n = 1,384) from nares samples and 18.1% (n = 842) from wound samples. MRSASelect II had an overall concordance of 95.4% (confidence interval [CI] = 94.5% to 96.2%) compared to a broth-enriched reference standard. Comparisons between results, stratified by examination times, exhibited a nonsignificant trend toward increased positivity at prolonged incubation times. Cefoxitin screening of colonies directly from MRSASelect II was 96.7% (95.8% to 97.3%) concordant compared to testing of colonies following broth enrichment. A comparison of MRSASelect and MRSASelect II revealed no statistical differences; however, the latter exhibited earlier positivity, greater selectivity, and more intense indicator staining, which resulted in facilitated differentiation of positive results. MRSASelect II agar is a simple, rapid, and robust method to routinely screen patients for MRSA colonization without the need for additional testing. PMID:26582836

  14. Sheep blood-LB agar base medium (SLM) as a simple and suitable medium for the cultivation of Leishmania major promastigotes.

    PubMed

    Nasiri, Vahid

    2013-11-01

    Several methods of cultivation of Leishmania parasites are available, and among them, biphasic media like Nicolle-Novy-MacNeal medium are considered to be superior for the initial isolation of the parasites and their in vivo infectivity. In the present work, the efficacy of sheep blood-LB agar base medium (SLM) was evaluated for the cultivation of Leishmania major promastigotes. The SLM supports the proliferation of the parasites and can be used for routine isolation and cultivation of Leishmania parasites with acceptable in vivo infectivity for research purposes.

  15. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin.

    PubMed

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C

    2015-03-21

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure-PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery. PMID:25716689

  16. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin

    NASA Astrophysics Data System (ADS)

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C.

    2015-03-01

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure—PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  17. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin.

    PubMed

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C

    2015-03-21

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure-PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  18. Study of gelatin-agar intermolecular aggregates in the supernatant of its coacervate.

    PubMed

    Singh, S Santinath; Bohidar, H B; Bandyopadhyay, S

    2007-05-15

    Intermolecular interaction leading to formation of aggregates between gelatin, a polyampholyte, and agar, a polysaccharide was studied in the supernatant of the complex coacervate formed by these biopolymers. Electrophoresis, laser light scattering and viscometry data were used to determine the interaction and the physical structure of these intermolecular soluble complexes by modeling these to be prolate ellipsoids of revolution (rod-like structures with well defined axial ratio and Perrin's factor). Solution ionic strength was found to reduce the axial ratio of these complexes implying the presence of screened polarization-induced electrostatic interaction between the two biopolymers.

  19. Methicillin-Resistant Staphylococcus aureus Grown on Vancomycin-Supplemented Screening Agar Displays Enhanced Biofilm Formation.

    PubMed

    Chang, Wenjiao; Ding, Ding; Zhang, Shanshan; Dai, Yuanyuan; Pan, Qing; Lu, Huaiwei; Luo, Qingli; Shen, Jilong; Ma, Xiaoling

    2015-12-01

    Brain heart infusion agar containing 3 mg/liter vancomycin (BHI-V3) was used to screen for heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). There was markedly greater biofilm formation by isolates that grew on BHI-V3 than by strains that did not grow on BHI-V3. Increased biofilm formation by hVISA may be mediated by FnbA- and polysaccharide intercellular adhesin-dependent pathways, and upregulation of atlA and sarA may also contribute to enhanced biofilm formation by hVISA upon prolonged exposure to vancomycin.

  20. Comparative study of 6-APA production by free and agar immobilized bacteria in nutrient broth culture.

    PubMed

    Dolui, A K; Das, S

    2011-04-01

    In the present study different bacterial samples were isolated from soil of different places of Dibrugarh and screened for biotransformation ability to produce 6-Aminopenicillanic acid. Among ten isolated bacterial samples, three gram positive bacterial samples designated as AKDD-2, AKDD-4 and AKDD-6 showed the production of 6-APA from penicillin G. Assessment of production of 6-APA after incubation in penicillin G (2 mg/ml) by three different samples separately in free and agar immobilization state was done by HPLC analysis. Reusability of immobilized cells was found successful up to 14 days. PMID:21614893

  1. CHROMagar Yersinia, a New Chromogenic Agar for Screening of Potentially Pathogenic Yersinia enterocolitica Isolates in Stools

    PubMed Central

    Renaud, Nicolas; Lecci, Laetitia; Courcol, René J.; Simonet, Michel

    2013-01-01

    CHROMagar Yersinia (CAY) is a new chromogenic medium for the presumptive detection of virulent Yersinia enterocolitica in stools. Based on a comparative analysis of 1,494 consecutive stools from hospitalized patients, CAY was found to be just as sensitive as the reference medium (cefsulodin-irgasan-novobiocin agar) but was significantly more specific and had a very low false-positive rate. CAY reduces the workload (and thus costs) for stool analysis and can therefore be recommended for routine laboratory use. PMID:23363840

  2. Comparative study of 6-APA production by free and agar immobilized bacteria in nutrient broth culture.

    PubMed

    Dolui, A K; Das, S

    2011-04-01

    In the present study different bacterial samples were isolated from soil of different places of Dibrugarh and screened for biotransformation ability to produce 6-Aminopenicillanic acid. Among ten isolated bacterial samples, three gram positive bacterial samples designated as AKDD-2, AKDD-4 and AKDD-6 showed the production of 6-APA from penicillin G. Assessment of production of 6-APA after incubation in penicillin G (2 mg/ml) by three different samples separately in free and agar immobilization state was done by HPLC analysis. Reusability of immobilized cells was found successful up to 14 days.

  3. Methicillin-Resistant Staphylococcus aureus Grown on Vancomycin-Supplemented Screening Agar Displays Enhanced Biofilm Formation.

    PubMed

    Chang, Wenjiao; Ding, Ding; Zhang, Shanshan; Dai, Yuanyuan; Pan, Qing; Lu, Huaiwei; Luo, Qingli; Shen, Jilong; Ma, Xiaoling

    2015-12-01

    Brain heart infusion agar containing 3 mg/liter vancomycin (BHI-V3) was used to screen for heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). There was markedly greater biofilm formation by isolates that grew on BHI-V3 than by strains that did not grow on BHI-V3. Increased biofilm formation by hVISA may be mediated by FnbA- and polysaccharide intercellular adhesin-dependent pathways, and upregulation of atlA and sarA may also contribute to enhanced biofilm formation by hVISA upon prolonged exposure to vancomycin. PMID:26459889

  4. Evaluation of Group B Streptococcus Differential Agar for detection and isolation of Streptococcus agalactiae.

    PubMed

    Bou, G; Figueira, M; Canle, D; Cartelle, M; Eiros, J M; Villanueva, R

    2005-08-01

    In total, 320 vaginal or rectal swabs were cultured on Granada medium (GM) or Group B Streptococcus Differential Agar (GBSDA), and were also inoculated into LIM broth (Todd-Hewitt broth supplemented with selective antibiotics), for detection of group B Streptococcus (GBS). Overall, GBS isolates were detected on 53 of the 320 swabs; 47 of these isolates grew on both GM and GBSDA, five only on GBSDA, and one only following subculture from LIM broth. GBSDA appears to be a valid alternative to GM for the growth of GBS isolates from pregnant women.

  5. Analysis of the Proportional Hazards Model with Sparse Longitudinal Covariates

    PubMed Central

    Cao, Hongyuan; Churpek, Mathew M.; Zeng, Donglin; Fine, Jason P.

    2014-01-01

    Regression analysis of censored failure observations via the proportional hazards model permits time-varying covariates which are observed at death times. In practice, such longitudinal covariates are typically sparse and only measured at infrequent and irregularly spaced follow-up times. Full likelihood analyses of joint models for longitudinal and survival data impose stringent modelling assumptions which are difficult to verify in practice and which are complicated both inferentially and computationally. In this article, a simple kernel weighted score function is proposed with minimal assumptions. Two scenarios are considered: half kernel estimation in which observation ceases at the time of the event and full kernel estimation for data where observation may continue after the event, as with recurrent events data. It is established that these estimators are consistent and asymptotically normal. However, they converge at rates which are slower than the parametric rates which may be achieved with fully observed covariates, with the full kernel method achieving an optimal convergence rate which is superior to that of the half kernel method. Simulation results demonstrate that the large sample approximations are adequate for practical use and may yield improved performance relative to last value carried forward approach and joint modelling method. The analysis of the data from a cardiac arrest study demonstrates the utility of the proposed methods. PMID:26576066

  6. Detection by hyperspectral imaging of shiga toxin-producing Escherichia coli serogroups O26, O45, O103, O111, O121, and O145 on rainbow agar.

    PubMed

    Windham, William R; Yoon, Seung-Chul; Ladely, Scott R; Haley, Jennifer A; Heitschmidt, Jerry W; Lawrence, Kurt C; Park, Bosoon; Narrang, Neelam; Cray, William C

    2013-07-01

    The U.S. Department of Agriculture, Food Safety Inspection Service has determined that six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) are adulterants in raw beef. Isolate and phenotypic discrimination of non-O157 STEC is problematic due to the lack of suitable agar media. The lack of distinct phenotypic color variation among non-O157serogroups cultured on chromogenic agar poses a challenge in selecting colonies for confirmation. In this study, visible and near-infrared hyperspectral imaging and chemometrics were used to detect and classify non-O157 STEC serogroups grown on Rainbow agar O157. The method was first developed by building spectral libraries for each serogroup obtained from ground-truth regions of interest representing the true identity of each pixel and thus each pure culture colony in the hyperspectral agar-plate image. The spectral library for the pure-culture non-O157 STEC consisted of 2,171 colonies, with spectra derived from 124,347 of pixels. The classification models for each serogroup were developed with a k nearest-neighbor classifier. The overall classification training accuracy at the colony level was 99%. The classifier was validated with ground beef enrichments artificially inoculated with 10, 50, and 100 CFU/ml STEC. The validation ground-truth regions of interest of the STEC target colonies consisted of 606 colonies, with 3,030 pixels of spectra. The overall classification accuracy was 98%. The average specificity of the method was 98% due to the low false-positive rate of 1.2%. The sensitivity ranged from 78 to 100% due to the false-negative rates of 22, 7, and 8% for O145, O45, and O26, respectively. This study showed the potential of visible and near-infrared hyperspectral imaging for detecting and classifying colonies of the six non-O157 STEC serogroups. The technique needs to be validated with bacterial cultures directly extracted from meat products and positive

  7. [A multicenter study of a new Helicobacter pylori selective medium. Columbia horse blood agar HP].

    PubMed

    Hasegawa, Miyuki; Amano, Ayako; Muraoka, Hiroe; Kobayashi, Intetsu; Kimoto, Mami; Kato, Mototsugu; Fujioka, Toshio; Nasu, Masaru

    2002-05-01

    We conducted a study for the growth of and selectivity for the desired microorganisms using a newly developed selective culture medium for Helicobacter pylori, Columbia horse blood agar HP (CHBHP), at three different Japanese clinical laboratories, Hokkaido, Kanto and Kyusyu. When standard strains and clinical isolates of H. pylori were examined, the recovery of the organism on the CHBHP media was comparable to that of conventional selective and nonselective media. However, colonies were obviously larger on the CHBHP media. These media yielded the highest H. pylori positive rate for clinical specimens at all the three laboratories. The detection rate of the CHBHP media in H. pylori-positive specimens was higher than that of media commonly used at the three laboratories (98.1% to 100% vs. 88.0% to 96.2%). The CHBHP media also achieved a higher detection rate for specimens from H. pylori-infected animals. CHBHP media have an excellent growth supporting ability and selectivity originating from Columbia agar base and do not require the combined use of non-selective media for the growth and isolation of the organism, resulting in lower cost. Thus, they are useful media for the selective culture and isolation of H. pylori from clinical and animal specimens.

  8. Measuring Survival of Hematopoietic Cancer Cells with the Colony-Forming Assay in Soft Agar.

    PubMed

    Crowley, Lisa C; Waterhouse, Nigel J

    2016-01-01

    Colony-forming assays measure the ability of cells in culture to grow and divide into groups. Any cell that has the potential to form a colony may also have the potential to cause cancer or relapse in vivo. Colony-forming assays also provide an indirect measurement of cell death because any cell that is dead or dying will not continue to proliferate. The proliferative capacity of adherent cells such as fibroblasts can be determined by growing cells at low density on culture dishes and counting the number of distinct groups that form over time. Cells that grow in suspension, such as hematopoietic cells, cannot be assayed this way because the cells move freely in the media. Assays to determine the colony-forming ability of hematopoietic cells must therefore be performed in solid matrices that restrict large-scale movement of the cells. One such matrix is soft agar. This protocol describes the use of soft agar to compare the colony-forming ability of untreated hematopoietic cells to the colony-forming ability of hematopoietic cells that have been treated with a cytotoxic agent. PMID:27480718

  9. An agar gel enzyme assay (AGEA) for simple detection of Salmonella enteritidis antibodies in chicken sera.

    PubMed

    Kim, C J; Nagaraja, K V

    1991-01-01

    An agar gel enzyme assay (AGEA) was developed for the detection of antibodies to Salmonella enteritidis (SE). The assay was based on the ability of antibodies to diffuse through an agar gel and react with antigen coated on a polystyrene surface. The antigen-antibody reaction was then made visible by applying an enzyme-conjugated anti-immunoglobulin and the addition, subsequently, of a substrate-containing gel. The color change in circular zones was taken as the indication for the presence of antibodies. The present investigation reports identification of an antigen specific for SE and its use in the development of a relatively simple AGEA procedure. The results of AGEA were compared with those of conventional microagglutination (MA) test and serum plate (SP) test. The percentage agreement between MA and AGEA in positive serum sample was found to be 94.4%, and in negative serum samples it was found to be 88.8%. The present results suggest that the AGEA could be a very useful screening test for the detection of SE antibodies because the assay is inexpensive, specific and simple to perform without much equipment, and give results within a 3-hr period. PMID:1832368

  10. Abolition of Swarming of Proteus by p-Nitrophenyl Glycerin: Application to Blood Agar Media

    PubMed Central

    Williams, Fred D.

    1973-01-01

    Comparative plate counts were made of Staphylococcus aureus and Streptococcus pyogenes growing on blood agar supplemented with individual chemicals to abolish the swarming of Proteus. B-phenylethanol, sodium azide, and p-nitrophenyl glycerin (PNPG) were used as anti-swarm agents. Each anti-swarm agent effectively abolished swarming for 24 h, but azide failed to control swarming for longer periods of incubation. In addition, azide displayed growth inhibition towards the staphylococci and streptococci resulting in no hemolysis and reduced viable cell numbers with the streptococci. Phenylethanol showed reduced viable cell numbers with the streptococci and unreliable hemolytic reactions. At 0.1 to 0.3 mM, PNPG proved to be a superior anti-swarm agent in that it showed no growth inhibition and allowed normal hemolysis, but abolished swarming for extended periods of time. When laboratory strains of Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa. Listeria monocytogenes, and Vibrio cholerae were screened on a blood agar medium containing 0.1 mm PNPG, they displayed similar growth and hemolytic characteristics to the identical medium without PNPG. PMID:4715553

  11. Evaluation of a Modified Cefsulodin-Irgasan-Novobiocin Agar for Isolation of Yersinia spp

    PubMed Central

    Tan, Lai Kuan; Ooi, Peck Toung; Carniel, Elisabeth; Thong, Kwai Lin

    2014-01-01

    Y. enterocolitica and Y. pseudotuberculosis are important food borne pathogens. However, the presence of competitive microbiota makes the isolation of Y. enterocolitica and Y. pseudotuberculosis from naturally contaminated foods difficult. We attempted to evaluate the performance of a modified Cefsulodin-Irgasan-Novobiocin (CIN) agar in the differentiation of Y. enterocolitica from non-Yersinia species, particularly the natural intestinal microbiota. The modified CIN enabled the growth of Y. enterocolitica colonies with the same efficiency as CIN and Luria-Bertani agar. The detection limits of the modified CIN for Y. enterocolitica in culture medium (10 cfu/ml) and in artificially contaminated pork (104 cfu/ml) were also comparable to those of CIN. However, the modified CIN provided a better discrimination of Yersinia colonies from other bacteria exhibiting Yersinia-like colonies on CIN (H2S-producing Citrobacter freundii, C. braakii, Enterobacter cloacae, Aeromonas hydrophila, Providencia rettgeri, and Morganella morganii). The modified CIN exhibited a higher recovery rate of Y. enterocolitica from artificially prepared bacterial cultures and naturally contaminated samples compared with CIN. Our results thus demonstrated that the use of modified CIN may be a valuable means to increase the recovery rate of food borne Yersinia from natural samples, which are usually contaminated by multiple types of bacteria. PMID:25170941

  12. Preparation and characterization agar-based nanocomposite film reinforced by nanocrystalline cellulose.

    PubMed

    Atef, Maryam; Rezaei, Masoud; Behrooz, Rabi

    2014-09-01

    Nanocrystalline cellulose (NCC) was prepared from microcrystalline cellulose (MCC) with particle size of 24.7 μm using sulfuric acid hydrolysis technique. The obtained NCC revealed size of 0-100 nm, which the major part of them was about 30 nm. Then different contents (2.5, 5 and 10 wt%) of these NCC incorporated in agar film solution and the morphology, structure, and properties of the nanocomposite films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), mechanical, physical and optical testing. Results showed that the water vapor permeability (WVP) and water solubility (WS) of the agar-based nanocomposite films significantly (P<0.05) decreased about 13% and 21%, respectively, upon increasing the NCC content to 10%. Tensile strength (TS) and Young's modulus (YM) values of nanocomposite films significantly increased (P≤0.05) with addition of NCC, whereas the elongation percent (E%) decreased not significantly (P>0.05). In addition, swelling percentage, transparency and light transmission of the films were decreased by incorporating NCC into polymer matrix.

  13. Evaluation of a modified Cefsulodin-Irgasan-Novobiocin agar for isolation of Yersinia spp.

    PubMed

    Tan, Lai Kuan; Ooi, Peck Toung; Carniel, Elisabeth; Thong, Kwai Lin

    2014-01-01

    Y. enterocolitica and Y. pseudotuberculosis are important food borne pathogens. However, the presence of competitive microbiota makes the isolation of Y. enterocolitica and Y. pseudotuberculosis from naturally contaminated foods difficult. We attempted to evaluate the performance of a modified Cefsulodin-Irgasan-Novobiocin (CIN) agar in the differentiation of Y. enterocolitica from non-Yersinia species, particularly the natural intestinal microbiota. The modified CIN enabled the growth of Y. enterocolitica colonies with the same efficiency as CIN and Luria-Bertani agar. The detection limits of the modified CIN for Y. enterocolitica in culture medium (10 cfu/ml) and in artificially contaminated pork (10(4) cfu/ml) were also comparable to those of CIN. However, the modified CIN provided a better discrimination of Yersinia colonies from other bacteria exhibiting Yersinia-like colonies on CIN (H2S-producing Citrobacter freundii, C. braakii, Enterobacter cloacae, Aeromonas hydrophila, Providencia rettgeri, and Morganella morganii). The modified CIN exhibited a higher recovery rate of Y. enterocolitica from artificially prepared bacterial cultures and naturally contaminated samples compared with CIN. Our results thus demonstrated that the use of modified CIN may be a valuable means to increase the recovery rate of food borne Yersinia from natural samples, which are usually contaminated by multiple types of bacteria. PMID:25170941

  14. Effect of post-treatments and concentration of cotton linter cellulose nanocrystals on the properties of agar-based nanocomposite films.

    PubMed

    Oun, Ahmed A; Rhim, Jong-Whan

    2015-12-10

    Cellulose nanocrystals (CNCs) were prepared by acid hydrolysis of cotton linter pulp fibers and three different purification methods, i.e., without post purification (CNC1), dialyzed against distilled water (CNC2), and neutralized with NaOH (CNC3), and their effect on film properties was evaluated by preparation of agar/CNCs composite films. All the CNCs were rod in shape with diameter of 15-50 nm and length of 210-480 nm. FTIR result indicated that there was no distinctive differences in the chemical structure between CNCs and cotton linter cellulose fiber. No significant relationship was observed between the sulfate content and crystallinity index of CNCs. The CNC3 showed higher thermal stability than the other type of CNCs due to the less adverse effect on the thermal stability of sulfate groups induced by the neutralization with NaOH. The tensile strength (TS) of agar film increased by 15% with incorporation of 5 wt% of CNC3, on the contrary, it decreased by 10% and 15% with incorporation of CNC1 and CNC2, respectively. Other performance properties of agar/CNCs composite films such as optical and water vapor barrier properties showed that the CNC3 was more effective filler than the other CNCs. In the range of concentration of CNC3 tested (1-10 wt%), inclusion of 5 wt% of CNC3 was the maximum concentration for improving or maintaining film properties of the composite films. The neutralization of acid hydrolyzed cellulose using NaOH was simple and convenient for the preparation of CNC and bionanocomposite films.

  15. Light-scattering sensor for real-time identification of Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae colonies on solid agar plate.

    PubMed

    Huff, Karleigh; Aroonnual, Amornrat; Littlejohn, Amy E Fleishman; Rajwa, Bartek; Bae, Euiwon; Banada, Padmapriya P; Patsekin, Valery; Hirleman, E Daniel; Robinson, J Paul; Richards, Gary P; Bhunia, Arun K

    2012-09-01

    The three most common pathogenic species of Vibrio, Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus, are of major concerns due to increased incidence of water- and seafood-related outbreaks and illness worldwide. Current methods are lengthy and require biochemical and molecular confirmation. A novel label-free forward light-scattering sensor was developed to detect and identify colonies of these three pathogens in real time in the presence of other vibrios in food or water samples. Vibrio colonies grown on agar plates were illuminated by a 635 nm laser beam and scatter-image signatures were acquired using a CCD (charge-coupled device) camera in an automated BARDOT (BActerial Rapid Detection using Optical light-scattering Technology) system. Although a limited number of Vibrio species was tested, each produced a unique light-scattering signature that is consistent from colony to colony. Subsequently a pattern recognition system analysing the collected light-scatter information provided classification in 1-2 min with an accuracy of 99%. The light-scattering signatures were unaffected by subjecting the bacteria to physiological stressors: osmotic imbalance, acid, heat and recovery from a viable but non-culturable state. Furthermore, employing a standard sample enrichment in alkaline peptone water for 6 h followed by plating on selective thiosulphate citrate bile salts sucrose agar at 30°C for ∼ 12 h, the light-scattering sensor successfully detected V. cholerae, V. parahaemolyticus and V. vulnificus present in oyster or water samples in 18 h even in the presence of other vibrios or other bacteria, indicating the suitability of the sensor as a powerful screening tool for pathogens on agar plates.

  16. Attention Modulation by Proportion Congruency: The Asymmetrical List Shifting Effect

    ERIC Educational Resources Information Center

    Abrahamse, Elger L.; Duthoo, Wout; Notebaert, Wim; Risko, Evan F.

    2013-01-01

    Proportion congruency effects represent hallmark phenomena in current theorizing about cognitive control. This is based on the notion that proportion congruency determines the relative levels of attention to relevant and irrelevant information in conflict tasks. However, little empirical evidence exists that uniquely supports such an attention…

  17. Longitudinal Enrollment Dynamics and Changes in Ethnic Proportionality.

    ERIC Educational Resources Information Center

    Greaves, Fred

    The Federal Racial/Ethnic Surveys of the Salinas Union High School District were examined to identify changes in ethnic proportions within a particular class from its entry in the 9th grade until the 12th grade. The 9th, 10th, 11th, and 12th grade proportional distributions are reported by school (Alisal High School, North Salinas High School, and…

  18. Development of Proportional Reasoning: Where Young Children Go Wrong

    ERIC Educational Resources Information Center

    Boyer, Ty W.; Levine, Susan C.; Huttenlocher, Janellen

    2008-01-01

    Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10 to 12 years of age, but can solve parallel problems involving continuous quantities by 6 years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A…

  19. The Failings of the Law of Definite Proportions

    ERIC Educational Resources Information Center

    Suchow, Lawrence

    1975-01-01

    Indicates that the concept of definite proportions or constant composition should be introduced with qualification. Presents arguments against the Law of Definite Proportions and cites examples in the areas of solid solutions, compounds of the transition and inner transition elements, and in some compounds of the representative elements. (GS)

  20. 16 CFR 240.9 - Proportionally equal terms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Proportionally equal terms. 240.9 Section 240.9 Commercial Practices FEDERAL TRADE COMMISSION GUIDES AND TRADE PRACTICE RULES GUIDES FOR ADVERTISING ALLOWANCES AND OTHER MERCHANDISING PAYMENTS AND SERVICES § 240.9 Proportionally equal terms....

  1. Understanding Proportional Reasoning in Pre-Service Teachers

    ERIC Educational Resources Information Center

    Johnson, Kim H.

    2013-01-01

    The purpose of this study is to examine the proportional reasoning of pre-service teachers at the beginning of their teacher preparation program using the developmental shifts described by Lobato and Ellis (2010). They cast changes in proportional reasoning as transitions or "shifts" in students' thinking and these shifts can serve as…

  2. The influence of lower face vertical proportion on facial attractiveness.

    PubMed

    Johnston, D J; Hunt, O; Johnston, C D; Burden, D J; Stevenson, M; Hepper, P

    2005-08-01

    This study investigated the influence of changing lower face vertical proportion on the attractiveness ratings scored by lay people.Ninety-two social science students rated the attractiveness of a series of silhouettes with normal, reduced or increased lower face proportions. The random sequences of 10 images included an image with the Eastman normal lower face height relative to total face height [lower anterior face height/total anterior face height (LAFH/TAFH) of 55 per cent], and images with LAFH/TAFH increased or decreased by up to four standard deviations (SD) from the Eastman norm. All the images had a skeletal Class I antero-posterior (AP) relationship. A duplicate image in each sequence assessed repeatability. The participants scored each image using a 10 point numerical scale and also indicated whether they would seek treatment if the image was their own profile. The profile image with normal vertical facial proportions was rated by the lay people as the most attractive. Attractiveness scores reduced as the vertical facial proportions diverged from the normal value. Images with a reduced lower face proportion were rated as significantly more attractive than the corresponding images with an increased lower face proportion. Images with a reduced lower face proportion were also significantly less likely to be judged as needing treatment than the corresponding images with an increased lower face proportion. PMID:15961569

  3. ESTIMATING PROPORTION OF AREA OCCUPIED UNDER COMPLEX SURVEY DESIGNS

    EPA Science Inventory

    Estimating proportion of sites occupied, or proportion of area occupied (PAO) is a common problem in environmental studies. Typically, field surveys do not ensure that occupancy of a site is made with perfect detection. Maximum likelihood estimation of site occupancy rates when...

  4. Development and Validation of a Successful Microbiological Agar Assay for Determination of Ceftriaxone Sodium in Powder for Injectable Solution

    PubMed Central

    Aléssio, Patrícia V.; Salgado, Hérida R. N.

    2012-01-01

    Ceftriaxone sodium is a cephalosporin with broad-spectrum antimicrobial activity and belongs to the third generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for the determination of ceftriaxone sodium in powder for injectable solution has not been reported yet. This paper reports the development and validation of a simple, accurate and reproducible agar diffusion method to quantify ceftriaxone sodium in powder for injectable solution. The assay is based on the inhibitory effect of ceftriaxone sodium on the strain of Bacillus subtilis ATCC 9371 IAL 1027 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.999) in the selected range of 15.0–60.0 μg/mL, precise with a relative standard deviation (RSD) of repeatability intraday = 1.40%, accurate (100.46%) and robust with a RSD lower than 1.28%. The results demonstrated the validity of the proposed bioassay, which allows reliable ceftriaxone sodium quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine. PMID:24300294

  5. Agar gel immunodiffusion analysis using baculovirus-expressed recombinant bovine leukemia virus envelope glycoprotein (gp51/gp30(T-)).

    PubMed

    Lim, Seong In; Jeong, Wooseog; Tark, Dong Seob; Yang, Dong Kun; Kweon, Chang Hee

    2009-12-01

    Bovine leukemia virus (BLV) envelope glycoprotein (gp51/ gp30(T-)), consisting of BLV gp51 and BLV gp30 that lacked its C-terminal transmembrane domain, was expressed in insect cells under the control of the baculovirus polyhedron promoter. Recombinant BLV gp51/gp30(T-) secreted from insect cells was determined by immunofluorescence, enzyme-linked immunosorbent and western blot assays using a BLV-specific monoclonal antibody and BLV-positive bovine antibodies. An agar gel immunodiffusion (AGID) test using gp51/gp30(T-) as the antigen for the detection of BLV antibodies in serum was developed and compared to traditional AGID, which uses wild type BLV antigen derived from fetal lamb kidney cells. AGID with the recombinant BLV gp51/gp30(T-) was relatively more sensitive than traditional AGID. When the two methods were tested with bovine sera from the field, the recombinant BLV gp51/gp30(T-) and traditional antigen had a relative sensitivity of 69.8% and 67.4%, respectively, and a relative specificity of 93.3% and 92.3%. These results indicated that the recombinant BLV gp51/gp30(T-) is an effective alternative antigen for the diagnosis of BLV infection in cattle.

  6. On the proportion of upward flashes to lightning research towers

    NASA Astrophysics Data System (ADS)

    Smorgonskiy, Alexander; Rachidi, Farhad; Rubinstein, Marcos; Diendorfer, Gerhard; Schulz, Wolfgang

    2013-07-01

    We compare in this paper direct measurements obtained on the towers on San Salvatore Mountain (Switzerland) and on the Gaisberg Mountain (Austria). They are situated in similar topographical environments but in different lightning activity zones. Direct measurements of lightning currents on these towers have revealed a major difference in terms of the number of downward flashes. While measurements made by Berger and co-workers revealed a significant number of downward flashes on the two towers on San Salvatore Mountain, more recent observations on the Gaisberg and Peissenberg towers were essentially composed of upward flashes. We use in this paper a new method to estimate the proportion of upward/downward flashes to a given tower, based on the data from lightning location systems. The analysis using the proposed method explains the discrepancy in terms of the measured number of downward flashes in the Gaisberg and San Salvatore towers. The analysis presented reveals also that in the evaluation of the percentage of upward flashes initiated from a tall structure, different parameters should be carefully examined, namely (i) the value of the ground flash density, (ii) the topographical conditions, and (iii) the presence of other tall structures in the region from which upward flashes might be initiated.

  7. Multichannel electrotactile feedback for simultaneous and proportional myoelectric control

    NASA Astrophysics Data System (ADS)

    Patel, Gauravkumar K.; Dosen, Strahinja; Castellini, Claudio; Farina, Dario

    2016-10-01

    Objective. Closing the loop in myoelectric prostheses by providing artificial somatosensory feedback to the user is an important need for prosthetic users. Previous studies investigated feedback strategies in combination with the control of one degree of freedom of simple grippers. Modern hands, however, are sophisticated multifunction systems. In this study, we assessed multichannel electrotactile feedback integrated with an advanced method for the simultaneous and proportional control of individual fingers of a dexterous hand. Approach. The feedback used spatial and frequency coding to provide information on the finger positions (normalized flexion angles). A comprehensive set of conditions have been investigated in 28 able-bodied subjects, including feedback modalities (visual, electrotactile and no feedback), control tasks (fingers and grasps), systems (virtual and real hand), control methods (ideal and realistic) and range of motion (low and high). The task for the subjects was to operate the hand using closed-loop myoelectric control and generate the desired movement (e.g., selected finger or grasp at a specific level of closure). Main results. The subjects could perceive the multichannel and multivariable electrotactile feedback and effectively exploit it to improve the control performance with respect to open-loop grasping. The improvement however depended on the reliability of the feedforward control, with less consistent control exhibiting performance trends that were more complex across the conditions. Significance. The results are promising for the potential application of advanced feedback to close the control loop in sophisticated prosthetic systems.

  8. Should fatty acid signature proportions sum to 1 for diet estimation?

    USGS Publications Warehouse

    Bromaghin, Jeffrey; Budge, Suzanne M.; Thiemann, Gregory W.

    2016-01-01

    Knowledge of predator diets, including how diets might change through time or differ among predators, provides essential insights into their ecology. Diet estimation therefore remains an active area of research within quantitative ecology. Quantitative fatty acid signature analysis (QFASA) is an increasingly common method of diet estimation. QFASA is based on a data library of prey signatures, which are vectors of proportions summarizing the fatty acid composition of lipids, and diet is estimated as the mixture of prey signatures that most closely approximates a predator’s signature. Diets are typically estimated using proportions from a subset of all fatty acids that are known to be solely or largely influenced by diet. Given the subset of fatty acids selected, the current practice is to scale their proportions to sum to 1.0. However, scaling signature proportions has the potential to distort the structural relationships within a prey library and between predators and prey. To investigate that possibility, we compared the practice of scaling proportions with two alternatives and found that the traditional scaling can meaningfully bias diet estimators under some conditions. Two aspects of the prey types that contributed to a predator’s diet influenced the magnitude of the bias: the degree to which the sums of unscaled proportions differed among prey types and the identifiability of prey types within the prey library. We caution investigators against the routine scaling of signature proportions in QFASA.

  9. Potato Dextrose Agar Antifungal Susceptibility Testing for Yeasts and Molds: Evaluation of Phosphate Effect on Antifungal Activity of CMT-3

    PubMed Central

    Liu, Yu; Tortora, George; Ryan, Maria E.; Lee, Hsi-Ming; Golub, Lorne M.

    2002-01-01

    The broth macrodilution method (BMM) for antifungal susceptibility testing, approved by the National Committee for Clinical Laboratory Standards (NCCLS), was found to have deficiencies in testing of the antifungal activity of a new type of antifungal agent, a nonantibacterial chemically modified tetracycline (CMT-3). The high content of phosphate in the medium was found to greatly increase the MICs of CMT-3. To avoid the interference of phosphate in the test, a new method using potato dextrose agar (PDA) as a culture medium was developed. Eight strains of fungi, including five American Type Culture Collection strains and three clinical isolates, were used to determine the MICs of amphotericin B and itraconazole with both the BMM and the PDA methods. The MICs of the two antifungal agents determined with the PDA method showed 99% agreement with those determined with the BMM method within 1 log2 dilution. Similarly, the overall reproducibility of the MICs with the PDA method was above 97%. Three other antifungal agents, fluconazole, ketoconazole, and CMT-3, were also tested in parallel against yeasts and molds with both the BMM and the PDA methods. The MICs of fluconazole and ketoconazole determined with the PDA method showed 100% agreement within 1 log2 dilution of those obtained with the BMM method. However, the MICs of CMT-3 determined with the BMM method were as high as 128 times those determined with the PDA method. The effect of phosphate on the antifungal activity of CMT-3 was evaluated by adding Na2HPO4 to PDA in the new method. It was found that the MIC of CMT-3 against a Penicillium sp. increased from 0.5 μg/ml (control) to 2.0 μg/ml when the added phosphate was used at a concentration of 0.8 mg/ml, indicating a strong interference of Na2HPO4 with the antifungal activity of CMT-3. Except for fluconazole, all the other antifungal agents demonstrated clear end points among the yeasts and molds tested. Nevertheless, with its high reproducibility, good

  10. M-RTLV agar, a novel selective medium to distinguish Lactobacillus casei and Lactobacillus paracasei from Lactobacillus rhamnosus.

    PubMed

    Sakai, Takafumi; Oishi, Kenji; Asahara, Takashi; Takada, Toshihiko; Yuki, Norikatsu; Matsumoto, Kazumasa; Nomoto, Koji; Kushiro, Akira

    2010-05-15

    We developed a novel selective medium, modified-rhamnose-2,3,5-triphenyltetrazolium chloride-LBS-vancomycin agar (M-RTLV agar), that utilizes the fermentability of L-rhamnose to distinguish Lactobacillus casei and Lactobacillus paracasei from Lactobacillus rhamnosus. Whereas L. casei and L. paracasei formed red colonies on the M-RTLV agar, L. rhamnosus formed either pink-toned colonies or white colonies with a red spot. An intervention study was conducted to confirm the capability of M-RTLV agar to detect ingested L. casei when recovered from human feces. Subjects consumed one bottle daily of a fermented milk product (Yakult or Yakult Light, which contains L. casei strain Shirota; LcS) for 7 days. Diluents of the fecal samples were cultivated on M-RTLV agar. We were able to enumerate circular medium-sized red colonies, which were morphologically similar to L. casei/L. paracasei but clearly distinguishable from the remaining colonies owing to the color difference. These colonies were then subjected to enzyme-linked immunosorbent assay in order to identify the LcS. The viable counts of LcS were 6.6+/-0.7 log(10) CFU/g feces after intake of Yakult and 6.5+/-0.6 log(10) CFU/g feces after intake of Yakult Light (mean+/-SD).

  11. Isolation and characterization of agar-digesting Vibrio species from the rotten thallus of Gracilariopsis heteroclada Zhang et Xia.

    PubMed

    Martinez, Joval N; Padilla, Philip Ian P

    2016-08-01

    Gracilariopsis heteroclada Zhang et Xia (Gracilariaceae, Rhodophyta) is one of the most studied marine seaweeds due to its economic importance. This has been cultivated extensively on commercial scale in the Philippines and other Asian countries. However, sustainable production of G. heteroclada in the Philippines could not be maximized due to the occurrence of rotten thallus disease. Thus, isolation and characterization of agar-digesting bacteria from the rotten thalli of G. heteroclada was conducted. A total of seven representative bacterial isolates were randomly selected based on their ability to digest agar as evidenced by the formation of depressions around the bacterial colonies on nutrient agar plates supplemented with 1.5% NaCl and liquefaction of agar. Gram-staining and biochemical characterization revealed that isolates tested were gram-negative rods and taxonomically identified as Vibrio parahaemolyticus (86-99.5%) and Vibrio alginolyticus (94.2-97.7%), respectively. It is yet to be confirmed whether these agar-digesting vibrios are involved in the induction and development of rotten thallus disease in G. heteroclada in concomitance with other opportunistic bacterial pathogens coupled with adverse environmental conditions. PMID:27285614

  12. Characteristics of rat megakaryocyte colonies and their progenitors in agar culture

    SciTech Connect

    Kellar, K.L.; Rolovic, Z.; Evatt, B.L.; Sewell, E.T.

    1985-11-01

    The characteristics of megakaryocyte colonies that develop from megakaryocyte progenitors of rat bone marrow stimulated by rat spleen-conditioned medium (SCM) in agar culture were investigated. Colony frequency was optimal on day 7 and increased relative to both the number of cells plated and the concentration of SCM used. Colonies were categorized as small cell and big cell. Small-cell colonies had a greater proliferative potential, with a mean of 25 cells/colony. Big-cell colonies averaged 15 cells/colony. The ratio of big-cell to small-cell colonies was 0.69 +/- 0.29. Granulocyte-macrophage colonies, which were also stimulated by SCM, accounted for 70% +/- 15% of the total colonies in the cultures. Cytocidal experiments with tritiated thymidine reduced megakaryocyte colony formation by 45% and granulocyte-macrophage colony formation by 21%. The properties of rat, mouse, and human megakaryocyte progenitors as assayed in vitro are compared.

  13. Injection of Acanthaster planci with thiosulfate-citrate-bile-sucrose agar (TCBS). I. Disease induction.

    PubMed

    Rivera-Posada, J A; Pratchett, M; Cano-Gómez, A; Arango-Gómez, J D; Owens, L

    2011-12-01

    This is the first report of the successful induction of a transmissible disease in the coral-eating crown-of-thorns starfish Acanthaster planci (COTS). Injection of thiosulfate-citrate-bile-sucrose agar (TCBS) culture medium into COTS induced a disease characterized by discoloured and necrotic skin, ulcerations, loss of body turgor, accumulation of colourless mucus on many spines especially at their tip, and loss of spines. Blisters on the dorsal integument broke through the skin surface and resulted in large, open sores that exposed the internal organs. Oedema and reddened digestive tissues and destruction of connective fibers were common. Moreover, healthy COTS in contact with these infected animals also displayed signs of disease and died within 24 h. TCBS induced 100% mortality in injected starfish. There was no introduction of new pathogens into the marine environment. TCBS promoted the growth of COTS' naturally occurring Vibrionales to high densities with subsequent symbiont imbalance followed by disease and death.

  14. Agar-Like Polysaccharide Produced by a Pseudomonas Species: Production and Basic Properties

    PubMed Central

    Kang, Kenneth S.; Veeder, George T.; Mirrasoul, Peter J.; Kaneko, Tatsuo; Cottrell, Ian W.

    1982-01-01

    A new species of Pseudomonas was isolated that produced copious amounts of an exocellular heteropolysaccharide (PS-60) after incubation for 3 days at 30°C in media containing 3% glucose as a carbon source. The polysaccharide was composed of approximately 46% glucose and 30% rhamnose and, in addition, contained 21% uronic acid and 3% O-acetyl. Upon deacetylation by a mild alkaline treatment, PS-60 produced a brittle, firm, and optically clear gel. This gelling property was thermoreversible. The PS-60 gel exhibited excellent heat stability that withstood autoclaving (i.e., 121°C for 15 min) for several cycles. The gel strength, melting point, and setting point of the polysaccharide were controlled primarily by the concentration of cations. PS-60 was not affected by a variety of enzymes. The results of tests involving various culture media and biochemical test media indicate that PS-60 is an excellent alternative gelling agent to agar. PMID:16346007

  15. Agar hydrogel with silver nanoparticles to prolong the shelf life of Fior di Latte cheese.

    PubMed

    Incoronato, A L; Conte, A; Buonocore, G G; Del Nobile, M A

    2011-04-01

    The objective of this work was to evaluate the effectiveness of an antimicrobial packaging system containing active nanoparticles on the quality deterioration of Fior di Latte cheese. To this aim, 3 concentrations of silver montmorillonite embedded in agar were used. The cell loads of spoilage and useful microorganisms were monitored during a refrigerated storage period. Moreover, cheese sensory quality (i.e., odor, color, consistency, and overall quality) was evaluated by means of a panel test. Results showed that the active packaging system markedly increased the shelf life of Fior di Latte cheese, due to the ability of silver cations to control microbial proliferation, without affecting the functional dairy microbiota and the sensory characteristics of the product. The active packaging system developed in this work could be used to prolong the shelf life of Fior di Latte and boost its distribution beyond local market borders.

  16. Serotyping reanalysis of unserotypable Actinobacillus pleuropneumoniae isolates by agar gel diffusion test

    PubMed Central

    MORIOKA, Ayako; SHIMAZAKI, Yoko; UCHIYAMA, Mariko; SUZUKI, Shoko

    2016-01-01

    We observed increasing unserotypable (UT) Actinobacillus pleuropneumoniae isolates using agar gel diffusion (AGD) test. To reanalyze their serovar, we performed rapid slide agglutination (RSA) test and multiplex PCR for 47 UT isolates. Of these, 25 were serovar 1 (UT-serovar 1), 20 were serovar 2 (UT-serovar 2) and 2 were serovar 15 (UT-serovar 15). We examined serotyping antigen extraction temperature to determine heat influence. UT-serovar 1 and 15 were influenced by heat, because their precipitation lines were observed in the case of low antigen extraction temperature. To investigate the relationship between antigenicity and genotype, we performed pulsed-field gel electrophoresis (PFGE) analysis using UT-serovar 2 and 15. The predominant PFGE pattern of UT-serovar 2 was identical to that of serovar 2. PMID:26726101

  17. Agar gel immunodiffusion assay to detect antibodies to Type A influenza virus.

    PubMed

    Jenson, Terra A

    2014-01-01

    The agar gel immunodiffusion (AGID) test is used to detect antibodies to Type A influenza group-specific antigens, i.e., the ribonucleoprotein (RNP) and matrix (M) proteins. Therefore, this test will detect antibodies to all influenza A virus subtypes. AGID is commonly used to screen poultry flocks for avian influenza virus infection. The AGID is a simple and economical serological test. All serological testing has its advantages and disadvantages which should be considered before choosing the optimal test for the laboratory needs. Each laboratory must evaluate the laboratory's resources, the volume of testing, the goal of testing, how the test results are used and what types of samples are being tested in order to select the optimal test.

  18. Bacterial culture detection and identification in blood agar plates with an optoelectronic nose.

    PubMed

    Lim, Sung H; Mix, Samantha; Anikst, Victoria; Budvytiene, Indre; Eiden, Michael; Churi, Yair; Queralto, Nuria; Berliner, Anders; Martino, Raymond A; Rhodes, Paul A; Banaei, Niaz

    2016-02-01

    Clinical microbiology automation is currently limited by the lack of an in-plate culture identification system. Using an inexpensive, printed, disposable colorimetric sensor array (CSA) responsive to the volatiles emitted into plate headspace by microorganisms during growth, we report here that not only the presence but the species of bacteria growing in plate was identified before colonies are visible. In 1894 trials, 15 pathogenic bacterial species cultured on blood agar were identified with 91.0% sensitivity and 99.4% specificity within 3 hours of detection. The results indicate CSAs integrated into Petri dish lids present a novel paradigm to speciate microorganisms, well-suited to integration into automated plate handling systems.

  19. AUTORADIOGRAPHIC ANALYSIS ON AGAR PLATES OF ANTIGENS FROM SUB CELLULAR FRACTIONS OF RAT LIVER SLICES

    PubMed Central

    Morgan, W. S.; Perlmann, P.; Hultin, T.

    1961-01-01

    Slices of rat livers were incubated with 14C amino acids, homogenized, and subjected to differential centrifugation. The microsomes were further extracted with the non-ionic detergent Lubrol W and with EDTA. These extracts and the microsome free "cell sap," freed from the pH 5 precipitable fraction, were subsequently reacted with antisera using agar diffusion techniques. The antisera employed were obtained from rabbits injected with different subcellular fractions of rat liver or with rat serum proteins. When the agar diffusion plates were autoradiographed it was found that some of the precipitates were radioactive while others were not. Control experiments indicated that this labeling was due to the specific incorporation of 14C amino acids into various rat liver antigens during incubation of the slices rather than to a non-specific adsorption of radioactive material to the immunological precipitates. When the slices were incubated with the isotope for up to 30 minutes, the serum proteins which could be extracted from the microsomes with the detergent were strongly labeled, as were a number of additional microsomal antigens of unknown significance. In contrast, the serum proteins present in the cell sap were only weakly labeled. Most of the typical cell sap proteins, both those precipitable and those soluble at pH 5, seemed to remain unlabeled. No consistently reproducible results were obtained with the EDTA extracts of the ribosomal residues remaining after extraction of the microsomes with the detergent. Incubation of the liver slices for longer periods (up to 120 minutes) led to a strong labeling of the serum proteins in the cell sap as well as to the appearance of labeling in additional cell sap proteins. The results are discussed with regard to the subcellular site of synthesis and the metabolism of the different antigens. PMID:13772607

  20. Evolutionary consequences of putative intra-and interspecific hybridization in agaric fungi.

    PubMed

    Hughes, Karen W; Petersen, Ronald H; Lodge, D Jean; Bergemann, Sarah E; Baumgartner, Kendra; Tulloss, Rodham E; Lickey, Edgar; Cifuentes, Joaquin

    2013-01-01

    Agaric fungi of the southern Appalachian Mountains including Great Smoky Mountains National Park are often heterozygous for the rDNA internal transcribed spacer region (ITS) with >42% of collections showing some heterozygosity for indels and/or base-pair substitutions. For these collections, intra-individual haplotype divergence is typically less than 2%, but for 3% of these collections intra-individual haplotype divergence exceeds that figure. We hypothesize that high intra-individual haplotype divergence is due to hybridization between agaric fungi with divergent haplotypes, possibly migrants from geographically isolated glacial refugia. Four species with relatively high haplotype divergence were examined: Armillaria mellea, Amanita citrina f. lavendula, Gymnopus dichrous and the Hygrocybe flavescens/chlorophana complex. The ITS region was sequenced, haplotypes of heterozygotes were resolved through cloning, and phylogenetic analyses were used to determine the outcome of hybridization events. Within Armillaria mellea and Amanita citrina f. lavendula, we found evidence of interbreeding and recombination. Within G. dichrous and H. flavescens/chlorophana, hybrids were identified but there was no evidence for F2 or higher progeny in natural populations suggesting that the hybrid fruitbodies might be an evolutionary dead end and that the genetically divergent Mendelian populations from which they were derived are, in fact, different species. The association between ITS haplotype divergence of less than 5% (Armillaria mellea = 2.6% excluding gaps; Amanita citrina f. lavendula = 3.3%) with the presence of putative recombinants and greater than 5% (Gymnopus dichrous = 5.7%; Hygrocybe flavescens/chlorophana = 14.1%) with apparent failure of F1 hybrids to produce F2 or higher progeny in populations may suggest a correlation between genetic distance and reproductive isolation. PMID:23928423

  1. Determination of agar tissue phantoms depth profiles with pulsed photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Milanič, Matija; Majaron, Boris; Nelson, J. Stuart

    2007-07-01

    Pulsed photothermal radiometry (PPTR) can be used for non-invasive depth profiling of skin vascular lesions (e.g., port wine stain birthmarks), aimed towards optimizing laser therapy on an individual patient basis. Optimal configuration of the experimental setup must be found and its performance characterized on samples with well defined structure, before introducing the technique into clinical practice. The aim of our study is to determine how sample structure and width of spectruml acquisition band affect the accuracy of measured depth profiles. We have constructed tissue phantoms composed of multiple layers of agar and of thin absorbing layers between the agar layers. Three phantoms had a single absorber layer at various depths between 100 and 500 μm, and one phantom had two absorber layers. In each sample we induced a non-homogeneous temperature profile with a 585 nm pulsed laser and acquired the resulting radiometric signal with a fast InSb infrared camera. We tested two configurations of the acquisition system, one using the customary 3-5 um spectruml band and one with a custom 4.5 μm cut-on filter. The laser-induced temperature depth profiles were reconstructed from measured PPTR signals using a custom algorithm and compared with sample structure as determined by histology and optical coherent tomography (OCT). PPTR determined temperature profiles correlate well with sample structure in all samples. Determination of the absorbing layer depth shows good repeatability with spatial resolution decreasing with depth. Spectruml filtering improved the accuracy of reconstructed profiles for shallow absorption layers (100-200 μm). PPTR technique enables reliable determination of structure in tissue phantoms with thin absorbing layers. Narrowing of the spectruml acquisition band (to 4.5 - 5.3 μm) improves reconstruction of objects near the surface.

  2. Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

    2013-02-01

    This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products.

  3. The proportion of cancer attributable to occupational exposures

    PubMed Central

    Purdue, Mark P.; Hutchings, Sally J.; Rushton, Lesley; Silverman, Debra T.

    2015-01-01

    Purpose To review the literature on the estimation of the population attributable fraction (PAF) of cancer due to occupational exposures and to describe challenges in the estimation of this metric. To help illustrate the inherent challenges, we also estimate PAFs for selected cancers diagnosed in the United States in 2010 attributable to work as a painter (causally associated with bladder and lung cancer) and shiftwork (possibly associated with breast cancer). Methods We reviewed and summarized previous reports providing quantitative estimates of PAF for total cancer due to occupational exposures. We calculated PAF estimates for painters and shiftwork using methodology from a detailed investigation of the occupational cancer burden in Great Britain, with adaptations made for the U.S. population. Results The estimated occupation-attributable fraction for total cancer generally ranged between 2% and 8% (men, 3-14%; women, 1-2%) based on previous reports. We calculated that employment as a painter accounted for a very small proportion of cancers of the bladder and lung diagnosed in the United States in 2010, with PAFs of 0.5% for each site. In contrast, our calculations suggest that the potential impact of shiftwork on breast cancer (if causal) could be substantial, with a PAF of 5.7%, translating to 11,777 attributable breast cancers. Conclusions Continued efforts to estimate the occupational cancer burden will be important as scientific evidence and economic trends evolve. Such projects should consider the challenges involved in PAF estimation, which we summarize in this report. PMID:25487971

  4. Proportional Hazards Model with Covariate Measurement Error and Instrumental Variables

    PubMed Central

    Song, Xiao; Wang, Ching-Yun

    2014-01-01

    In biomedical studies, covariates with measurement error may occur in survival data. Existing approaches mostly require certain replications on the error-contaminated covariates, which may not be available in the data. In this paper, we develop a simple nonparametric correction approach for estimation of the regression parameters in the proportional hazards model using a subset of the sample where instrumental variables are observed. The instrumental variables are related to the covariates through a general nonparametric model, and no distributional assumptions are placed on the error and the underlying true covariates. We further propose a novel generalized methods of moments nonparametric correction estimator to improve the efficiency over the simple correction approach. The efficiency gain can be substantial when the calibration subsample is small compared to the whole sample. The estimators are shown to be consistent and asymptotically normal. Performance of the estimators is evaluated via simulation studies and by an application to data from an HIV clinical trial. Estimation of the baseline hazard function is not addressed. PMID:25663724

  5. Articular to diaphyseal proportions of human and great ape metatarsals.

    PubMed

    Marchi, Damiano

    2010-10-01

    This study proposes a new way to use metatarsals to identify locomotor behavior of fossil hominins. Metatarsal head articular dimensions and diaphyseal strength in a sample of chimpanzees, gorillas, orangutans, and humans (n = 76) are used to explore the relationships of these parameters with different locomotor modes. Results show that ratios between metatarsal head articular proportions and diaphyseal strength of the hallucal and fifth metatarsal discriminate among extant great apes and humans based on their different locomotor modes. In particular, the hallucal and fifth metatarsal characteristics of humans are functionally related to the different ranges of motion and load patterns during stance phase in the forefoot of humans in bipedal locomotion. This method may be applicable to isolated fossil hominin metatarsals to provide new information relevant to debates regarding the evolution of human bipedal locomotion. The second to fourth metatarsals are not useful in distinguishing among hominoids. Further studies should concentrate on measuring other important qualitative and quantitative differences in the shape of the metatarsal head of hominoids that are not reflected in simple geometric reconstructions of the articulation, and gathering more forefoot kinematic data on great apes to better understand differences in range of motion and loading patterns of the metatarsals.

  6. Feasible method for routine surveillance culturing of stools from neutropenic patients.

    PubMed Central

    Smith, J A; Sherlock, C H; Burdge, D R

    1984-01-01

    This study was undertaken to develop an accurate, yet inexpensive, method for determining whether the bowel of a neutropenic patient is colonized with bacteria resistant to the antimicrobial agents used in empiric therapy. Selective agar media were prepared in which Mueller-Hinton agar or MacConkey agar were supplemented with one of the following antimicrobial agents: carbenicillin (16 micrograms/ml), gentamicin (4 micrograms/ml), or tobramycin (4 micrograms/ml). Moxalactam was incorporated initially at 16 micrograms/ml and subsequently at 8 micrograms/ml. Stools from neutropenic patients and bone marrow transplant recipients were inoculated on these media and on unsupplemented MacConkey agar. All bacteria that grew on the antibiotic-containing media were categorized as resistant to the supplementing drug; failure to detect an organism that did grow on the antibiotic-free MacConkey agar indicated susceptibility. These results were compared with those obtained for all isolates on all media by agar disk diffusion. There were 512 gram-negative enteric isolates from 320 stools obtained from 98 patients. The antibiotic-containing media suppressed the growth of 95% of bacteria that were identified as susceptible by agar disk diffusion. In detecting resistant organisms, the correlation between agar disk diffusion and direct stool screening with Mueller-Hinton agar ranged from 73 to 83%, and on MacConkey agar it ranged from 87 to 97%. The predictive value of a resistant result was 80 to 97% for the four antimicrobial agents when MacConkey agar was used. MacConkey agar performed better than Mueller-Hinton agar because of the greater ease of detecting different bacterial morphotypes. The cost of direct stool screening with antibiotic-supplemented MacConkey agar is approximately half the cost of routine methods of surveillance. Its cost and accuracy make the method a useful adjunct to the routine management of neutropenic patients. PMID:6394620

  7. Enhanced chlorine resistance of tap water-adapted Legionella pneumophila as compared with agar medium-passaged strains.

    PubMed Central

    Kuchta, J M; States, S J; McGlaughlin, J E; Overmeyer, J H; Wadowsky, R M; McNamara, A M; Wolford, R S; Yee, R B

    1985-01-01

    Previous studies have shown that bacteria maintained in a low-nutrient "natural" environment such as swimming pool water are much more resistant to disinfection by various chemical agents than strains maintained on rich media. In the present study a comparison was made of the chlorine (Cl2) susceptibility of hot-water tank isolates of Legionella pneumophila maintained in tap water and strains passaged on either nonselective buffered charcoal-yeast extract or selective differential glycine-vancomycin-polymyxin agar medium. Our earlier work has shown that environmental and clinical isolates of L. pneumophila maintained on agar medium are much more resistant to Cl2 than coliforms are. Under the present experimental conditions (21 degrees C, pH 7.6 to 8.0, and 0.25 mg of free residual Cl2 per liter, we found the tap water-maintained L. pneumophila strains to be even more resistant than the agar-passaged isolates. Under these conditions, 99% kill of tap water-maintained strains of L. pneumophila was usually achieved within 60 to 90 min compared with 10 min for agar-passaged strains. Samples from plumbing fixtures in a hospital yielded legionellae which were "super"-chlorine resistant when assayed under natural conditions. After one agar passage their resistance dropped to levels of comparable strains which had not been previously exposed to additional chlorination. These studies more closely approximate natural conditions than our previous work and show that tap water-maintained L. pneumophila is even more resistant to Cl2 than its already resistant agar medium-passaged counterpart. PMID:3896142

  8. Variation in the excitability of developed D. discoideum cells as a function of agar concentration in the substrate

    NASA Astrophysics Data System (ADS)

    Oikawa, Noriko; Bae, Albert; Amselem, Gabriel; Bodenschatz, Eberhard

    2010-03-01

    In the absence of nutrients, Dictyostelium discoideum cells enter a developmental cycle--they signal each other, aggregate, and ultimately form fruiting bodies. During the signaling stage, the cells relay waves of cyclic adenosine 3',5' monophosphate (cAMP). We observed a transition from spiral to circular patterns in the signaling wave, depending on the agar concentration of the substrate. In this talk we will present the changes in the times for the onset of signaling and synchronization versus agar concentration, as measured by spectral entropy. We also will discuss the origin of these effects.

  9. Proportional proximity sensing for telerobots using Coherent Laser Radar

    NASA Technical Reports Server (NTRS)

    Vazquez, Sixto L.; Goode, Plesent W.; Slotwinski, Anthony R.

    1992-01-01

    The ability of a telerobotic manipulator to operate in confined spaces while avoiding unwanted collisions is enhanced by the accurate sensing of its proximate environment. To achieve the fidelity required for precise manipulator control, a proportional proximity sensor system with a sufficiently large measurement envelope is required. Current proximity sensors provide a binary indication of the presence of obstacles within a small envelope with coarse or no proportional measurement of their location. A proportional proximity sensor system configured as a Frequency Modulated Continuous Wave (FMCW) Coherent Laser Radar (CLR) using a semiconductor laser as the energy source is described and analyzed. The source and reflected energies mix coherently to generate a radio frequency (RF) signal whose frequency is proportional to the range. The system is tested for accuracy, range, depth of range, speed, and sensitivity and the results are presented. Techniques to derive orientation information and an application to telerobotic control are also described.

  10. DC motor proportional control system for orthotic devices

    NASA Technical Reports Server (NTRS)

    Blaise, H. T.; Allen, J. R.

    1972-01-01

    Multi-channel proportional control system for operation of dc motors for use with externally-powered orthotic arm braces is described. Components of circuitry and principles of operation are described. Schematic diagram of control circuit is provided.

  11. Description of an ionization calorimeter complemented with proportional counters

    NASA Technical Reports Server (NTRS)

    Babayan, K. P.; Boyadzhyan, N. G.; Vasiltsov, V. V.; Grigorov, N. L.; Sobinyakov, V. A.; Shestoperov, V. Y.

    1975-01-01

    An ionization calorimeter is described with a system of proportional counters which are used to determine the charge of the particles incident to the calorimeter and to estimate the number of the secondary charged particles.

  12. Proportional reasoning in the learning of chemistry: levels of complexity

    NASA Astrophysics Data System (ADS)

    Ramful, Ajay; Narod, Fawzia Bibi

    2014-03-01

    This interdisciplinary study sketches the ways in which proportional reasoning is involved in the solution of chemistry problems, more specifically, problems involving quantities in chemical reactions (commonly referred to as stoichiometry problems). By building on the expertise of both mathematics and chemistry education research, the present paper shows how the theoretical constructs in proportional reasoning in mathematics education offer rich explanatory accounts of the complexities involved in solving stoichiometry problems. Using Vergnaud's concept of measure spaces, the theoretical analysis shows that proportionality situations are relatively more intricate, involving various layers of complexity in chemistry as compared to those in the mathematics curriculum. Knowledge of proportionality and chemistry are simultaneously required to provide solutions to chemical reactions. Our analysis of a range of stoichiometry situations led us to propose a problem analysis framework involving five levels of difficulty. Further, the specificity of proportionality in stoichiometry is that it can only be established when quantities are interpreted in the unit "mole," a unit which does not have any physical embodiment in terms of a measure of quantity unlike mass and volume. Our analysis of student-teachers' solution to the stoichiometry problems, shows that they tend to incorrectly (probably intuitively) set proportional relationships when two quantities in a reaction are expressed in non-molar quantities such as mass. The data also bring to the fore the primarily formulaic approach that student-teachers use in setting inherent proportionality relationships. An important finding is the interpretation of a chemical equation as a mathematical equation, rather than a statement of proportionality.

  13. Proportioning and performance evaluation of self-consolidating concrete

    NASA Astrophysics Data System (ADS)

    Wang, Xuhao

    A well-proportioned self-consolidating concrete (SCC) mixture can be achieved by controlling the aggregate system, paste quality, and paste quantity. The work presented in this dissertation involves an effort to study and improve particle packing of the concrete system and reduce the paste quantity while maintaining concrete quality and performance. This dissertation is composed of four papers resulting from the study: (1) Assessing Particle Packing Based Self-Consolidating Concrete Mix Design; (2) Using Paste-To-Voids Volume Ratio to Evaluate the Performance of Self-Consolidating Concrete Mixtures; (3) Image Analysis Applications on Assessing Static Stability and Flowability of Self-Consolidating Concrete, and (4) Using Ultrasonic Wave Propagation to Monitor Stiffening Process of Self-Consolidating Concrete. Tests were conducted on a large matrix of SCC mixtures that were designed for cast-in-place bridge construction. The mixtures were made with different aggregate types, sizes, and different cementitious materials. In Paper 1, a modified particle-packing based mix design method, originally proposed by Brouwers (2005), was applied to the design of self-consolidating concrete (SCC) mixs. Using this method, a large matrix of SCC mixes was designed to have a particle distribution modulus (q) ranging from 0.23 to 0.29. Fresh properties (such as flowability, passing ability, segregation resistance, yield stress, viscosity, set time and formwork pressure) and hardened properties (such as compressive strength, surface resistance, shrinkage, and air structure) of these concrete mixes were experimentally evaluated. In Paper 2, a concept that is based on paste-to-voids volume ratio (Vpaste/Vvoids) was employed to assess the performance of SCC mixtures. The relationship between excess paste theory and Vpaste/Vvoids was investigated. The workability, flow properties, compressive strength, shrinkage, and surface resistivity of SCC mixtures were determined at various ages

  14. Development of a Colony Lift Immunoassay To Facilitate Rapid Detection and Quantification of Escherichia coli O157:H7 from Agar Plates and Filter Monitor Membranes

    PubMed Central

    Ingram, David T.; Lamichhane, Chinta M.; Rollins, David M.; Carr, Lewis E.; Mallinson, Edward T.; Joseph, Sam W.

    1998-01-01

    E. coli O157:H7 is a food-borne adulterant that can cause hemorrhagic ulcerative colitis and hemolytic uremic syndrome. Faced with an increasing risk of foods contaminated with E. coli O157:H7, food safety officials are seeking improved methods to detect and isolate E. coli O157:H7 in hazard analysis and critical control point systems in meat- and poultry-processing plants. A colony lift immunoassay was developed to facilitate the positive identification and quantification of E. coli O157:H7 by incorporating a simple colony lift enzyme-linked immunosorbent assay with filter monitors and traditional culture methods. Polyvinylidene difluoride (PVDF) membranes (Millipore, Bedford, Mass.) were prewet with methanol and were used to make replicates of every bacterial colony on agar plates or filter monitor membranes that were then reincubated for 15 to 18 h at 36 ± 1°C, during which the colonies not only remained viable but were reestablished. The membranes were dried, blocked with blocking buffer (Kirkegaard and Perry Laboratories [KPL], Gaithersburg, Md.), and exposed for 7 min to an affinity-purified horseradish peroxidase-labeled goat anti-E. coli O157 antibody (KPL). The membranes were washed, exposed to a 3,3′,5,5′-tetramethylbenzidine membrane substrate (TMB; KPL) or aminoethyl carbazole (AEC; Sigma Chemical Co., St. Louis, Mo.), rinsed in deionized water, and air dried. Colonies of E. coli O157:H7 were identified by either a blue (via TMB) or a red (via AEC) color reaction. The colored spots on the PVDF lift membrane were then matched to their respective parent colonies on the agar plates or filter monitor membranes. The colony lift immunoassay was tested with a wide range of genera in the family Enterobacteriaceae as well as different serotypes within the E. coli genus. The colony lift immunoassay provided a simple, rapid, and accurate method for confirming the presence of E. coli O157:H7 colonies isolated on filter monitors or spread plates by traditional

  15. Estimation of aquifer scale proportion using equal area grids: assessment of regional scale groundwater quality

    USGS Publications Warehouse

    Belitz, Kenneth; Jurgens, Bryant C.; Landon, Matthew K.; Fram, Miranda S.; Johnson, Tyler D.

    2010-01-01

    The proportion of an aquifer with constituent concentrations above a specified threshold (high concentrations) is taken as a nondimensional measure of regional scale water quality. If computed on the basis of area, it can be referred to as the aquifer scale proportion. A spatially unbiased estimate of aquifer scale proportion and a confidence interval for that estimate are obtained through the use of equal area grids and the binomial distribution. Traditionally, the confidence interval for a binomial proportion is computed using either the standard interval or the exact interval. Research from the statistics literature has shown that the standard interval should not be used and that the exact interval is overly conservative. On the basis of coverage probability and interval width, the Jeffreys interval is preferred. If more than one sample per cell is available, cell declustering is used to estimate the aquifer scale proportion, and Kish's design effect may be useful for estimating an effective number of samples. The binomial distribution is also used to quantify the adequacy of a grid with a given number of cells for identifying a small target, defined as a constituent that is present at high concentrations in a small proportion of the aquifer. Case studies illustrate a consistency between approaches that use one well per grid cell and many wells per cell. The methods presented in this paper provide a quantitative basis for designing a sampling program and for utilizing existing data.

  16. To evaluate the validity of Recurring Esthetic Dental proportion in natural dentition

    PubMed Central

    Shetty, Shilpa; Pitti, Varun; Satish Babu, CL; Surendra Kumar, GP; Jnanadev, KR

    2011-01-01

    Background: Different proportions are described in the literature for smile designing, such as Golden proportion, Golden percentage, Preston's proportion, and recently, Recurring Esthetic Dental (RED) proportion. Aims and Objectives: To evaluate the existence of RED proportion in natural dentition. To determine the relative height of maxillary lateral incisor and canine occurring in natural dentition so that it can be used in any of the above proportions. Materials and Methods: Fifteen male subjects and 15 female subjects in each of the different age groups of 18–23 years, 24–29 years and 30–35 years were selected for this study (total 90). Photographs of the subjects were taken using Nikon D200 camera with 135 mm lens and analyzed using Adobe Photoshop CS4 extended software. The height and width of maxillary central incisors, lateral incisors and canines were found out using the measuring tool provided in the software. Results: Average width ratio and height ratio of maxillary lateral incisor to central incisor and maxillary canine to lateral incisor were calculated to check the existence of RED proportion in natural dentition. Average lateral incisor to central incisor height ratio for “small”- and “medium”-sized teeth was found to be 88% and for “tall”-sized teeth was found to be 84%. Average canine to lateral incisor height ratio for “small”- and “medium”-sized teeth was found to be 106% and for “tall”-sized teeth was found to be 105%. Conclusions: Within the limitations of the study, RED proportion was not seen in natural dentition. PMID:22025841

  17. ["Golden proportion" and its application to calculate dentition].

    PubMed

    Vadachkoriia, N R; Gumberidze, N Sh; Mandzhavidze, N A

    2007-01-01

    Within an evolutionary process, the nature has created the standard of aesthetics - a "gold proportion" on the basis of which, the parts of human body, to be more exact, teeth and denture correspond to each other and to own parts by the size, which is the ideal precondition for ideal appearance. The charming smile serves as the proof, that teeth in denture are located by a principle of "gold proportion". A "gold proportion" is the corner stone of beauty and it can be applied with success in stomatology. Proportion is the certain ratio between parts, and proportional means a proper correlation of parts among themselves. It is reputed, that knowledge about "gold proportion" Pythagor has got from products of the Egyptian and Babylon scientists. And this is true, proportions of cult constructions, bas-relieves, pyramids in Giza, home appliances and ornaments from Tutanhamon tomb testify, that under their creation the Egyptian masters were guided by a principle of "gold proportion". The facade of ancient Greek temple Parthenon is built by a principle of "gold proportion". During archeological digs of this temple the compasses which sculptors and architects of an ancient world used has been found. The "gold proportion" is mentioned in the work which has reached us "Beginning" the author is the scientist of antique epoch Euclid. In 1509, in Venice the book of Luka Pacholi the "Divine proportion" has been published, its illustration is attributed to Leonardo de Vinci. This work has been recognized as a "Hymn of a gold proportion". In 1885 the German researcher professor Zeising published his work - "Aesthetic researches". When Zeising has received numerical values of piece length, he saw that they coincided with figures of some numerical sequence, which was offered by the great Italian mathematician of Middle Ages Fibonacci (or Leonardo Pisano). In his composition the "Abacus Book" Leonardo Fibonacci showed aforesaid sequence of numbers, by means of which he has explained

  18. ["Golden proportion" and its application to calculate dentition].

    PubMed

    Vadachkoriia, N R; Gumberidze, N Sh; Mandzhavidze, N A

    2007-01-01

    Within an evolutionary process, the nature has created the standard of aesthetics - a "gold proportion" on the basis of which, the parts of human body, to be more exact, teeth and denture correspond to each other and to own parts by the size, which is the ideal precondition for ideal appearance. The charming smile serves as the proof, that teeth in denture are located by a principle of "gold proportion". A "gold proportion" is the corner stone of beauty and it can be applied with success in stomatology. Proportion is the certain ratio between parts, and proportional means a proper correlation of parts among themselves. It is reputed, that knowledge about "gold proportion" Pythagor has got from products of the Egyptian and Babylon scientists. And this is true, proportions of cult constructions, bas-relieves, pyramids in Giza, home appliances and ornaments from Tutanhamon tomb testify, that under their creation the Egyptian masters were guided by a principle of "gold proportion". The facade of ancient Greek temple Parthenon is built by a principle of "gold proportion". During archeological digs of this temple the compasses which sculptors and architects of an ancient world used has been found. The "gold proportion" is mentioned in the work which has reached us "Beginning" the author is the scientist of antique epoch Euclid. In 1509, in Venice the book of Luka Pacholi the "Divine proportion" has been published, its illustration is attributed to Leonardo de Vinci. This work has been recognized as a "Hymn of a gold proportion". In 1885 the German researcher professor Zeising published his work - "Aesthetic researches". When Zeising has received numerical values of piece length, he saw that they coincided with figures of some numerical sequence, which was offered by the great Italian mathematician of Middle Ages Fibonacci (or Leonardo Pisano). In his composition the "Abacus Book" Leonardo Fibonacci showed aforesaid sequence of numbers, by means of which he has explained

  19. Proportional counter for X-ray analysis of lunar and planetary surfaces. [a position sensitive scintillating imaging proportional counter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A position sensitive proportional scintillation detector was developed and evaluated for use in applications involving X-ray imaging as well as spectroscopy. Topics covered include limitations of the proportional scintillation counter for use in space; purification of the xenon gas in the detector, and the operation of the detector system. Results show that the light signal in a proportional scintillation detector remains well localized. With modest electric fields in xenon, the primary electrons from a photoelectric absorption of an X-ray can be brought a distance of a few millimeters to a higher field region without spreading more than a millimeter or so. Therefore, it is possible to make a proportional scintillation detector with good position sensitivity that could be used to calibrate out the difference in light collection over its sensitive volume.

  20. The Proportion of Regulatory T Cells in Patients with Rheumatoid Arthritis: A Meta-Analysis

    PubMed Central

    Morita, Takayoshi; Shima, Yoshihito; Wing, James Badger; Sakaguchi, Shimon; Kumanogoh, Atsushi

    2016-01-01

    Background Regulatory T cells (Tregs) have important functions in peripheral immune tolerance. Dysfunction of Tregs is considered to be a pivotal cause of autoimmune diseases, including rheumatoid arthritis (RA). However, previous reports describing the proportion of Tregs among CD4+ T cells in RA patients were controversial because a range of markers are used to identify Tregs with little consensus. To clarify the status of Tregs in RA, we investigated the proportion of Tregs with focusing on the definitions of them. Methods We identified the studies reporting the proportion of Tregs in RA patients using PubMed and Google Scholar. We performed a systematic review of them and a meta-analysis to evaluate the proportion of Tregs (FOXP3-positive and/or CD25-positive) among CD4+ T cells in peripheral blood (PB) and synovial fluid (SF) of RA patients and control subjects. Results A total 31 studies were selected. The proportion of Tregs defined by all definitions among CD4+ T cells in PB was not significantly different between RA patients and control subjects (-0.65, [-1.30, 0.01]). Then we performed sub-analyses based on individual definitions. The proportion of Tregs defined by either CD25 or FOXP3 alone did not differ between RA patients and control subjects. The proportion of Tregs defined by both FOXP3 and CD25 was lower in RA patients than that in control subjects (-2.42 [-3.49, -1.34]). The proportion of Tregs defined by both FOXP3 and CD25 was higher in SF than that in PB among RA patients (3.27 [0.40, 6.14]). Conclusion The status of Tregs varied according to the definition system. The proportion of Tregs defined by stricter and functionally validated methods decreased in PB and increased in SF among RA patients. If the proportion of Tregs differs in RA, accurate and functionally relevant definitions of Tregs are necessary to elucidate their status in RA. PMID:27622457