Journal articles on the topic 'Low temperature storage assay'
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Eriksson, Hans, Johan Brengdahl, Petter Sandström, Mattias Rohman, and Bruno Becker. "Validation of Low-Volume 1536-Well Assay-Ready Compound Plates." Journal of Biomolecular Screening 14, no. 5 (May 21, 2009): 468–75. http://dx.doi.org/10.1177/1087057109335324.
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Assay-ready compound plates (ARPs) are sealed assay plates that contain DMSO solutions of screening compounds predispensed for particular assays. Assays are started by adding assay buffer and reagents to the ARPs. This concept offers important logistical advantages for screening such as decoupling of the plate preparation from the screening process and exchange of assay plates between different geographical locations. Compound solutions can be accurately and precisely dispensed by acoustic droplet ejection technology in the small volumes required for screening in the 1536-well format. At such low volumes, however, potential effects such as solvent evaporation, compound degradation, precipitation, or adsorption are reasons for concern with regard to assay reproducibility, performance, and shelf life of ARPs. To address these concerns, the authors screened freshly prepared ARPs using several types of assays. The results were compared to results obtained from plates stored for up to 13 days under 2 storage conditions (22 °C, —18 °C). Tight correlations between results were found that indicated that temperature and time had very little influence on the assay performance for up to about 1 week storage time of the plates. In addition, using a time series of microphotographs of DMSO droplets, the authors visually confirmed that the sizes of the droplets in ARPs apparently do not change over 13 days under certain storage conditions.
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Zhang, Jing, Xue-ren Yin, Heng Li, Meng Xu, Meng-xue Zhang, Shao-jia Li, Xiao-fen Liu, Yan-na Shi, Donald Grierson, and Kun-song Chen. "ETHYLENE RESPONSE FACTOR39–MYB8 complex regulates low-temperature-induced lignification of loquat fruit." Journal of Experimental Botany 71, no. 10 (February 19, 2020): 3172–84. http://dx.doi.org/10.1093/jxb/eraa085.
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Abstract Flesh lignification is a specific chilling response that causes deterioration in the quality of stored red-fleshed loquat fruit (Eribotrya japonica) and is one aspect of wider chilling injury. APETALA2/ETHLENE RESPONSIVE FACTOR (AP2/ERF) transcription factors are important regulators of plant low-temperature responses and lignin biosynthesis. In this study, the expression and action of 27 AP2/ERF genes from the red-fleshed loquat cultivar ‘Luoyangqing’ were investigated in order to identify transcription factors regulating low-temperature-induced lignification. EjERF27, EjERF30, EjERF36, and EjERF39 were significantly induced by storage at 0 °C but inhibited by a low-temperature conditioning treatment (pre-storage at 5 °C for 6 days before storage at 0 °C, which reduces low-temperature-induced lignification), and their transcript levels positively correlated with flesh lignification. A dual-luciferase assay indicated that EjERF39 could transactivate the promoter of the lignin biosynthetic gene Ej4CL1, and an electrophoretic mobility shift assay confirmed that EjERF39 recognizes the DRE element in the promoter region of Ej4CL1. Furthermore, the combination of EjERF39 and the previously characterized EjMYB8 synergistically transactivated the Ej4CL1 promoter, and both transcription factors showed expression patterns correlated with lignification in postharvest treatments and red-fleshed ‘Luoyangqing’ and white-fleshed ‘Ninghaibai’ cultivars with different lignification responses. Bimolecular fluorescence complementation and luciferase complementation imaging assays confirmed direct protein–protein interaction between EjERF39 and EjMYB8. These data indicate that EjERF39 is a novel cold-responsive transcriptional activator of Ej4CL1 that forms a synergistic activator complex with EjMYB8 and contributes to loquat fruit lignification at low temperatures.
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Waite, K. V., G. F. Maberly, and C. J. Eastman. "Storage conditions and stability of thyrotropin and thyroid hormones on filter paper." Clinical Chemistry 33, no. 6 (June 1, 1987): 853–55. http://dx.doi.org/10.1093/clinchem/33.6.853.
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Abstract We evaluated the effects of temperature and humidity on thyroid hormones (T4, T3) and thyrotropin (TSH) measured in blood spots dried on filter paper. RIAs for T4 and T3 blood spots were optimized to measure these analytes over the neonatal and euthyroid adult reference intervals. Sensitivities of the T3 and T4 assays were 0.5 and 10 nmol/L, respectively. A blood-spot immunoradiometric assay for TSH involving magnetizable particles was developed with a sensitivity of 6 milli-int. units/L. Control sera stored at -20 degrees C, 4 degrees C, room temperature, 37 degrees C, and at external ambient temperatures for 36 days showed no significant change in measured concentrations of TSH or T3 during 30 days or for T4 at -20 and 4 degrees C. T4 markedly declined in blood spots stored at room temperature (either high or low humidity), 37 degrees C, or ambient temperature. TSH and T3 in blood spots evidently are stable at temperatures likely to be encountered during storage or transport, but blood spots for T4 assay must be stored between -20 and 4 degrees C.
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Di Marino, L., A. Maffettone, P. Cipriano, E. Celentano, R. Galasso, C. Iovine, F. Berrino, and S. Panico. "Assay of erythrocyte membrane fatty acids. Effects of storage time at low temperature." International Journal of Clinical and Laboratory Research 30, no. 4 (December 2000): 197–202. http://dx.doi.org/10.1007/bf02874182.
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Di Marino, L., A. Maffettone, P. Cipriano, E. Celentano, R. Galasso, C. Iovine, F. Berrino, and S. Panico. "Assay of erythrocyte membrane fatty acids. Effects of storage time at low temperature." International Journal of Clinical & Laboratory Research 30, no. 4 (December 31, 2000): 197–202. http://dx.doi.org/10.1007/s005990070007.
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Riedel, T. E., J. C. Cox, and A. D. Ellington. "Low Temperature Microplate Station." JALA: Journal of the Association for Laboratory Automation 10, no. 1 (February 2005): 29–34. http://dx.doi.org/10.1016/j.jala.2004.10.002.
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The automation of biological laboratory assays may require lengthy incubations of reagents on the work surface of a pipetting robot. Commercial devices are readily available for keeping these reagents accessible and warm, but there are few existing technologies for storing accessible reagents below the freezing point of water. Here, we introduce a low cost, small footprint, robot accessible reagent cooler, based on compressor technology capable of acting as an enzyme freezer or extreme cold reagent storage device.
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Beers, Eric P., and Wallace G. Pill. "Respiratory Characterization of Germinated Tomato Seeds Stored in Gels at Low Temperatures." Journal of the American Society for Horticultural Science 111, no. 6 (November 1986): 918–21. http://dx.doi.org/10.21273/jashs.111.6.918.
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Abstract Germinated seeds of ‘Heinz 1350 VF’ tomato (Lycopersicon esculentum Mill.) were subjected to short-term (through 5 days) low temperature (0° or 5°C) storage suspended in 2 fluid-drilling gels (Natrosol 250 HHR or Laponite 445). Following storage, a greenhouse emergence assay and respiratory characterization via double inhibitor titrations (0.4/mM KCN and 10.0/mM salicylhydroxamic acid) were conducted. After 3-day storage in Natrosol or moist cheesecloth, emergence was about 90% but had decreased to <60% following 3-day storage in Laponite. With 5-day storage in Natrosol, 0° drastically reduced seedling vigor relative to that at 5°. Total O2 consumption by all stored germinated seeds was less than that of unstored germinated seeds. Consumption of O2 via both the cytochrome and alternative respiratory pathways was not affected differentially by storage temperature or gel. The maximum inducible rate of oxygen consumption via the alternative pathway decreased during storage in Natrosol at 0° or Laponite at 5° relative to that of unstored seeds or seeds stored in Natrosol at 5°.
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SHIEH, Y. CAROL, DIANA S. STEWART, and DAVID T. LAIRD. "Survival of Hepatitis A Virus in Spinach during Low Temperature Storage." Journal of Food Protection 72, no. 11 (November 1, 2009): 2390–93. http://dx.doi.org/10.4315/0362-028x-72.11.2390.
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Spinach leaves are frequently consumed raw and have been involved with past foodborne outbreaks. In this study, we examined the survival of hepatitis A virus (HAV) on fresh spinach leaves in moisture- and gas-permeable packages that were stored at 5.4 ± 1.2°C for up to 42 days. Different eluents including phosphate-buffered saline (PBS), pH 7.5 (with and without 2% serum), and 3% beef extract (pH 7.5 and 8) were compared for how efficiently they recovered viruses from spinach by using a simple elution procedure (<1 h). The recoveries were compared and determined by a plaque assay with FRhK-4 cells. Culture grade PBS containing 2% serum was found to be appropriate for HAV elution from spinach leaves, with an average recovery of 45% ± 10%. Over 4 weeks of storage at 5.4 ± 1.2°C, HAV in spinach decreased slightly more than 1 log, with 6.75% of the original titer remaining. HAV survived under refrigerated temperatures on spinach leaves with a D-value of 28.6 days (equivalent to an inactivation rate of 20.035 log of HAV per day, r2 = 0.88). In comparison, HAV in PBS containing 2% serum under the same storage conditions remained constant throughout 7 weeks. The inactivation rate of 20.035 log each day for HAV on spinach leaves was possibly due to the interaction of the virus and the leaf.
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Kleczkowski, Leszek A., and Gerald E. Edwards. "Hysteresis and Reversible Cold Inactivation of Maize Phosphoenolpyruvate Carboxylase." Zeitschrift für Naturforschung C 45, no. 1-2 (February 1, 1990): 42–46. http://dx.doi.org/10.1515/znc-1990-1-209.
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Abstract Maize (Zea mays L.) leaf phosphoenolpyruvate (PEP) carboxylase (PEPCase) (EC 4.1.1.31) showed a lag in activity when assayed after storage at 0-4 °C. The lag was promoted by high pH on storage (7.8 -8.5) and was observed over a range of assay pH (7.1 -8.5). Thermal reactivation of the cold-stored enzyme by assay temperature (18 °C) accounted for most of the hysteretic effect, but presence of PEP in the reaction mixture was required to completely eliminate the lag. Based on steady-state rates after the lag, stability of PEPCase in the cold was independent of protein concentration . It is suggested that low temperature and high pH induce a change in the oligomerization state of PEPCase, resulting in a less active but relatively stable form of the enzyme. The lag probably reflects a reversal of this process, promoted by assay temperature and presence of PEP.
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Jansen, Jan, Pamela L. Nolan, Margaret I. Reeves, Luke Paul Akard, James M. Thompson, Michael J. Dugan, and Susan G. Hanks. "The Effect of Physical Conditions on the Transportation of Peripheral Blood Progenitor (PBPC) Products." Blood 112, no. 11 (November 16, 2008): 2315. http://dx.doi.org/10.1182/blood.v112.11.2315.2315.
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Abstract The viability of transported PBPC products has not been studied extensively. Commonly, PBPC products are transported at a concentration of >200 x109/l in containers with −20oC ice packs. Continuous temperature monitoring has shown that the temperatures of these products stays at <10oC for less than 24 hours and reaches room temperature by 48 hours. Samples of freshly collected PBPC from 12 allogeneic donors were studied for various viability parameters during storage for up to 96 hours. The effects of storage time, concentration of cells, temperature, and storage in gas-permeable bags were studied. Trypan-blue exclusion and double fluorescence for 7-AAD and CD34 were used for viability assessment. Over a wide range of temperatures and storage times, the viable CD34+ assay was more sensitive to damage than trypan-blue exclusion (mean Δ 10.7%, p<0.0001 in paired t-test). The viable CD34+ assay was routinely used in parallel with CFU-GM cultures. No difference in survival of viable CD34+ cells or CFU-GM was found whether cells were incubated for 48hr in test-tubes or in gas-permeable bags. When cells at 200 x 109/l were incubated for 48hr at room temperature, the mean viability decreased to 19% and 6% of starting values of viable CD34+ cells and CFU-GM, respectively. Serial dilution to 25 x 109/l improved the survival to 81% and 51% respectively. Similarly, incubation at lower temperatures led to better survival of CD34+ cells and CFU-GM: 67% and 18% at 17oC, 80% and 50% at 13oC, and 95% and 86% at 4oC. At 200 x109/l and 22oC the survivals of CD34+ cells and CFU-GM were 74% and 21% at 24hr, 19% and 7% at 48hr, 7% and 6% at 72hr, and 3% and 13% at 96hr. The effects of concentration, temperature and duration of storage were all significant (p<0.05). Transportation at 4oC leads to the best survival of CD34+ cells and CFU-GM, in particular at a low concentration. If transportation at a slightly higher temperature is necessary, dilution of the PBPC product will enhance the survival of CD34+ cells and CFU-GM. Proliferative assays such as CFU-GM appear the most sensitive parameters of PBPC survival, and should be included in the validation process of PBPC transportation.
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Roes Lie, Indra Syahputra, Joshita Djajadisastra, and Fadlina Chany Saputri. "GREEN TEA EXTRACT IN AN EYELASH GROWTH ENHANCER GEL FORMULATION: STABILITY TEST, EYE IRRITATION TEST, AND HUMAN EYELASH GROWTH ACTIVITY." Asian Journal of Pharmaceutical and Clinical Research 10, no. 6 (June 1, 2017): 243. http://dx.doi.org/10.22159/ajpcr.2017.v10i6.18605.
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Objective: To formulate a green tea extract (GTE), which is often used as a hair growth product, to produce an eyelash gel with good stability, effectiveness, and safety for growing eyelashes.Methods: GTE was formulated into a gel. A stability test was performed at a high temperature (40±2°C), room temperature (25±2°C), low temperature (4±2°C), and a cycling temperature. An in vitro hen’s egg test-chorioallantoic membrane assay was performed to evaluate potential eye irritation. An eyelash growth test was conducted by length measurement using an eyelash ruler before and after 2 mo of application in human volunteers. Results: The GTE gel was stable in storage at high, room, and low temperatures and at cycling temperatures and did not cause eye irritation. Eyelashes grew significantly more in the test group than in the placebo group after 2 mo of application (p<0.05). Conclusion: GTE gel provides a new, safe, and effective option for growing natural eyelashes.
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Ilic, Zoran, Avital Ben-Yosef, Yaccov Partzelan, Sharon Alkalai-Tuvia, and Elazar Fallik. "Total antioxidant activity (TAA) of bell pepper during prolonged storage on low temperature." Journal of Agricultural Sciences, Belgrade 53, no. 1 (2008): 3–12. http://dx.doi.org/10.2298/jas0801003i.
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Bell pepper (Capsicum annum L.) is a vegetable known for its antioxidant content, highly important for its nutritional values. The total antioxidant activity (TAA) of pepper fruits is measured by TEAC (Trolox equivalent antioxidant capacity). This assay measures both the hydrophilic (HAA) (vitamin C) and lipophilic (LAA)(carotenoids and vitamin E) contents based on the total radical scavenging capacity and the ability of a scaverenge the stable ABTS radical (ABTS + ) described by Vinocur and Rodov (2006). Fruit were cleaned and disinfected with hot water by rinsing and brushing (HWRB) at 55?C as it is described by Fallik et all ., (1999). Tap water wash was served as control. Fruit were stored at 2?C or 7?C during 3 weeks plus 3 days at 20?C (shelf life simulation). TAA in red bell pepper, immediately after harvest, was 4.29 (0.74 lipophilic and 3,55 hydrophilic) mol TE/g fr.wt. After 3 weeks storage at 2?C, TAA in pepper with cold wash treatment was 4.14 and 3.97 TEAC mol TE/g fr.wt. in HWRB treatment. After 3weeks +3days shelf life on 20?C TAA slowly growing up and obtained content of 5.24 in cold wash and 5.16 TEAC mol TE/g fr.wt. in HWRB. This is mainly due to changes in the lipophilic activity-LAA (treatment with cold water-1.79 and 1.81 mol TE/g fr.wt. in HWRB, comparing with 0.74 mol TE/g fr.wt. on beginning of storage). Hydrophilic antioxidant activity-HAA remains practically unchanged. In fruit, stored at 7?C, pepper ripeness has been associated with carotenoids accumulation especially after shelf life, TAA was 5.33 TEAC ( LAA 2.03) mol TE/g fr.wt.
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Ivanova, Violeta, Marina Stefova, and Borimir Vojnoski. "Assay of the phenolic profile of merlot wines from Macedonia: Effect of maceration time, storage, SO2 and temperature of storage." Macedonian Journal of Chemistry and Chemical Engineering 28, no. 2 (December 15, 2009): 141. http://dx.doi.org/10.20450/mjcce.2009.203.
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Spectrophotometric assays of total anthocyanins, total phenolics, total catechins, total flavonoids, color intesity and hue were performed on Merlot wines obtained with 3, 6 and 10 days of maceration, containing 30 and 70 ppm SO2. Changes of phenolic contents were observed during three stages of the wines: after maceration, after 6 and 16 months in order to check the effect of maceration time, SO2 and storage of the wines. Wines were stored at low and higher temperature to check also the influence of storage temperature on the studied parameters. It was found that maceration time influences the content of polyphenol compounds, observing increasing of their concentrations with increased maceration time, while lower contents were measured in the wines after 16 months of storage (3006, 1732 and 1602 mg/l total phenolics and 478, 188 and 98.5 mg/l total anthocyanins, after maceration, after 6 and 16 months of storage, respectively, in wine with 30 ppm SO2). SO2 had not a significant effect, whereas higher temperature caused slight changes of polyphenols contents.
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Migliore, Brooke, Linran Zhou, Martin Duparc, Veronica Robles, Catherine Rehder, Holly Peay, and Katerina Kucera. "Evaluation of the GSP Creatine Kinase-MM Assay and Assessment of CK-MM Stability in Newborn, Patient, and Contrived Dried Blood Spots for Newborn Screening for Duchenne Muscular Dystrophy." International Journal of Neonatal Screening 8, no. 1 (January 28, 2022): 12. http://dx.doi.org/10.3390/ijns8010012.
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Duchenne Muscular Dystrophy (DMD) is a fatal X-linked disorder with a birth prevalence of 19.8:100,000 males worldwide. Elevated concentration of the muscle enzyme creatine kinase-MM (CK-MM) allows for presymptomatic screening of newborns using Dried Blood Spots (DBS). We evaluated imprecision and carryover of the FDA-approved PerkinElmer GSP Neonatal CK-MM kit over multiple runs, days, and operators, followed by quantification of CK-MM loss in stored newborn, contrived, and non-newborn patient DBS resulting from exposure to ambient versus low humidity (50-day trial), and high humidity and high temperature (8-day trial). Imprecision %CV was ≤14% for all verification comparisons and over 6 months of testing. On average, the mean CK-MM recovery after 50 days was >80% of initial concentration for all sample types stored in low humidity and <80% in ambient humidity. After 8 days of storage in high humidity and high temperature, the mean recovery for newborn samples was <80%. Verification results for the GSP Neonatal CK-MM assay were concordant with kit parameters and the assay performed consistently over 6 months. CK-MM degradation in ambient storage can be mitigated by reducing exposure to humidity. Assessment of DBS shipping and storage conditions is recommended prior to implementing DMD screening.
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Yoshikuni, Keiko, Takashi Matsuda, Janka Poracova, Akemi Sakai, Keiko Shimada, Noriko Tabuchi, and Kiyoh Tanishima. "Phylogenic Study of Denaturation of Lactate Dehydrogenase Isoenzymes from Different Species by High and Low Temperature." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 38, no. 5 (September 2001): 548–53. http://dx.doi.org/10.1177/000456320103800513.
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We studied the influence of storage at different temperatures on lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes from different tissues and different species, and analysed biochemical and biophysical mechanisms of denaturation during storage. Isoenzymes obtained from tissue extracts of mammals, poultry, reptiles, amphibians and fish were shown to have their own denaturation ranges at low temperatures by post-treatment assays and transition temperature analysis. These ranges were between − 10 and − 20°C for most vertebrate LD isoenzymes. Circular dichroism analysis indicated that the denaturation of LD isoenzymes was probably caused by a change in the hydrophobic interactions in the molecule. At higher temperatures, LD-1 isoenzyme was more thermostable than LD-5 from the same animal species, except for rats, the LD-5 activity of which was more thermostable than the LD-1 activity. These findings indicate that variable effects of storage of samples and reference materials at low temperatures should be considered, and that it is necessary to establish LD isoenzyme standards for animal clinical laboratory investigations.
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Limmatvapirat (1), Chutima, Juree Charoenteeraboon, Penpan Wetwitayaklung, Chanokporn Sukonpan, and Thawatchai Phaechamud. "Stability and Antioxidant Activity of Polyphenols in Methanolic Extracts of Sonneratia caseolaris Seeds." Advanced Materials Research 146-147 (October 2010): 1062–65. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1062.
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Polyphenols in methanolic extracts from Sonneratia caseolaris seeds were determined by HPLC coupled with electrospray mass spectrometry and quantified by HPLC coupled with ultraviolet/visible detection in order to evaluate their stability of the extracts during 6 months of storage. Antioxidant activity was measured by using TEAC assay, and the free radical scavenging activity was monitored in the initial 3 months of the stability evaluation. Study on the effect of temperature on the stability of the methanolic extract indicated that gallic acid, luteolin-7-O-glucoside, and luteolin were unstable at 25 and 45°C during storage time. At -80 and 4°C the quantities of luteolin-7-O-glucoside reduced while those of luteolin increased at the same time. The results suggested that luteolin-7-O-glucoside was hydrolyzed to luteolin. Therefore the polyphenols should be kept at low temperature. Antioxidant activity of methanolic extract was preserved in all temperatures during the first 3 months.
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Haisma, Sjoukje-Marije, Patrick Ferry van Rheenen, Lucie Wagenmakers, and Anneke Muller Kobold. "Calprotectin instability may lead to undertreatment in children with IBD." Archives of Disease in Childhood 105, no. 10 (January 17, 2019): 996–98. http://dx.doi.org/10.1136/archdischild-2018-316584.
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BackgroundTreatment decisions in children with inflammatory bowel disease (IBD) are increasingly based on longitudinal tracking of faecal calprotectin concentrations, but there is little known about the stability of this protein in stool.MethodsWe stored aliquots of homogenised stool at room temperature and at 4°C, and measured the calprotectin concentration for 6 consecutive days with three different assays. In addition, we assessed calprotectin stability in assay-specific extraction buffers kept at room temperature.ResultsAfter 6 days of storage at room temperature, mean percentage change from baseline calprotectin concentrations in stool and extraction buffer was 35% and 46%, respectively. The stability of calprotectin was significantly better preserved in samples stored at 4°C (p=0.0066 and 0.0011, respectively).ConclusionsCalprotectin is not stable at room temperature. Children with IBD and their caretakers may be falsely reassured by low calprotectin values. The best advisable standard for preanalytical calprotectin handling is refrigeration of the stool sample until delivery at the hospital laboratory.
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KENNEDY, NICOLE M., NABANITA MUKHERJEE, and PRATIK BANERJEE. "Escherichia coli O157:H7 Cells Exposed to Lettuce Leaf Lysate in Refrigerated Conditions Exhibit Differential Expression of Selected Virulence and Adhesion-Related Genes with Altered Mammalian Cell Adherence." Journal of Food Protection 79, no. 7 (July 1, 2016): 1259–65. http://dx.doi.org/10.4315/0362-028x.jfp-15-504.
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ABSTRACT Contamination by and persistence of pathogenic bacteria in ready-to-eat produce have emerged as significant food safety and public health concerns. Viable produceborne pathogens cope with several stresses (e.g., temperature fluctuations and low-temperature storage) during production and storage of the commodities. In this study, we investigated the impact of transient cold shock on Escherichia coli O157:H7 (EcO157) cells in a produce matrix (romaine lettuce leaf lysate). EcO157 cells were exposed to 25°C for 1 h, 4°C for 1 h, and 4°C for 10 min in lettuce lysate. The expression of selected genes coding for virulence, stress response, and heat and cold shock proteins was quantified by real-time quantitative reverse transcription PCR assay. Treated EcO157 cells adhered to MAC-T mammalian cells were enumerated by in vitro bioassay. Expression of the Shiga toxin 1 gene (stx1a) was upregulated significantly (P < 0.05) upon cold shock treatments, but virulence genes related to EcO157 attachment (eaeA, lpfA, and hcpA) were down-regulated. Two key members of the cold shock regulon, cold shock protein (cspA) and gyrA, were significantly induced (P < 0.05) at the refrigeration temperature (4°C). Significant upregulation of an SOS response gene, recA, was also observed. E. coli heat shock regulon member grpE was induced, but a universal stress protein (uspA) was down-regulated at the refrigeration temperatures in lettuce lysate. The adhesion assay revealed a temperature-dependent reduction in the attachment of cold-shocked EcO157 cells. The results of the current study indicate a reduction in the attachment of cold-shocked EcO157 to epithelial cells and higher levels of Shiga toxin gene expression at the molecular level.
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Mota, R. M., A. S. Silva, V. H. S. Ramos, J. C. T. Rezende, and E. de Jesus. "Effects of storage temperature and time on false setting behavior of CPI-S Portland cement." Cerâmica 66, no. 379 (September 2020): 321–29. http://dx.doi.org/10.1590/0366-69132020663792842.
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Abstract The false setting is when cement stiffens prematurely in a few minutes after adding water. Some variables could cause false setting in CPI-S-32 Portland cement, for example, alkali concentration in the cement, the formation of alite (C3S) with low reactivity, and cement storage temperature and time in silos. Temperature increases cause calcium sulfate dihydrate to dehydrate, forming hemihydrate (CaSO4.0.5H2O) or anhydrite (CaSO4), which causes the false setting. In this study, the influence of cement storage temperature (100, 105, 110, 120, and 130 °C) combined with the cement storage time (30, 60, and 120 min) in a silo was studied regarding the CPI-S-32 false setting behavior. It was verified that temperatures above 110 °C and storage time above 60 min are conditions that favor the false setting of CPI-S-32 cement. Physicochemical analysis, TG/DTG, XRF, and XRD were applied as complementary analyzes for the false setting assays of CPI-S-32.
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Yamashita, K., S. Ishida, and H. Funahashi. "24 EFFECT OF CULTURE OF SEMEN IN A LOW PRESSURE CONDITION AT ROOM TEMPERATURE ON VIABILITY AND CAPACITATION STATUS OF BOAR SPERM." Reproduction, Fertility and Development 23, no. 1 (2011): 118. http://dx.doi.org/10.1071/rdv23n1ab24.
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Sperm are affected by physical conditions, such as centrifugation and temperature. The objective of this study was to examine the effect of a low atmospheric pressure on viability and capacitation status of boar sperm during semen preservation at room temperature. Sperm-rich fraction from Berkshire boars was diluted at cells mL–1 with modified Modena containing 20% seminal fluid after washing with centrifugation (300 × g for 35 min at room temperature) in a Percoll gradient (45%/90%). The sperm suspension was stored at a pressure of 0.5 or 1.0 atmospheres in the dark at room temperature (25°C). Following storage for 4 h or 4 days, the semen samples were analysed for viability, intracellular calcium level, and acrosome status of the sperm. Viability and intracellular calcium level of sperm were assessed by flow cytometry following staining with SYBR-Green/PI and Furo-3/PL, respectively. Sperm status associated with capacitation and acrosome reaction was analysed by CTC-assay under fluorescence microscope. Statistical analyses of data from 4 or 5 replicated trials were carried out by ANOVA and with a Bonferroni-Dunn post hoc test (significance, P < 0.05). Viability of sperm was not different (P = 0.50) between 2 pressures (0.5 and 1.0 atm) 4 h and 4 days after the start of storage (94.6% v. 95.6% and 92.7% v. 94.3%, respectively). Although the percentage of live sperm with high intracellular calcium levels drastically increased (P < 0.01) 4 days after the start of storage (20.2% v. 23.4%) compared with 4 h of storage (5.5% v. 4.9%), there were no differences between sperm stored in 0.5 and 1.0 atm at 4 h (P = 0.80) and 4 days of storage (P = 0.40). After 4 h of storage, there were no differences in the percentage of intact (93.3% v. 94.7%), capacitated (5.5% v. 4.3%), and acrosome-reacted sperm (1.5% v. 1.5%) between sperm stored in 0.5 and 1.0 atm. After 4 days of storage, however, the percentage of intact sperm decreased when the sperm suspension was cultured in 0.5 atm (71.8%) compared with 1.0 atm (88.5%), and the incidence of capacitated sperm increased (14.3% v. 7.8%, respectively), whereas there was no difference in the acrosome-reacted cells. These results demonstrate that the status of sperm associated capacitation is stimulated in a low atmospheric pressure without any effects of the viability of sperm, during storage for 4 days.
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Scavone, Mariangela, Silvia Bozzi, Tatiana Mencarini, Gianmarco Podda, Marco Cattaneo, and Alberto Redaelli. "Platelet Adhesion and Thrombus Formation in Microchannels: The Effect of Assay-Dependent Variables." International Journal of Molecular Sciences 21, no. 3 (January 23, 2020): 750. http://dx.doi.org/10.3390/ijms21030750.
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Microfluidic flow chambers (MFCs) allow the study of platelet adhesion and thrombus formation under flow, which may be influenced by several variables. We developed a new MFC, with which we tested the effects of different variables on the results of platelet deposition and thrombus formation on a collagen-coated surface. Methods: Whole blood was perfused in the MFC over collagen Type I for 4 min at different wall shear rates (WSR) and different concentrations of collagen-coating solutions, keeping blood samples at room temperature or 37 °C before starting the experiments. In addition, we tested the effects of the antiplatelet agent acetylsalicylic acid (ASA) (antagonist of cyclooxygenase-1, 100 µM) and cangrelor (antagonist of P2Y12, 1 µM). Results: Platelet deposition on collagen (I) was not affected by the storage temperature of the blood before perfusion (room temperature vs. 37 °C); (II) was dependent on a shear rate in the range between 300/s and 1700/s; and (III) was influenced by the collagen concentration used to coat the microchannels up to a value of 10 µg/mL. ASA and cangrelor did not cause statistically significant inhibition of platelet accumulation, except for ASA at low collagen concentrations. Conclusions: Platelet deposition on collagen-coated surfaces is a shear-dependent process, not influenced by the collagen concentration beyond a value of 10 µg/mL. However, the inhibitory effect of antiplatelet drugs is better observed using low concentrations of collagen.
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Nasheri, Neda, Jennifer Harlow, Angela Chen, Nathalie Corneau, and Sabah Bidawid. "Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods." Food and Environmental Virology 13, no. 1 (January 27, 2021): 107–16. http://dx.doi.org/10.1007/s12560-020-09457-7.
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AbstractEnteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses have low infectious dose, and may remain infectious for weeks in the environment and food. Limited information is available regarding viral survival and transmission in low-moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne viral outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during 4-week storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR) using the modified ISO-15216 method as well as the magnetic bead assay for viral recovery. We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that the examined foodborne viruses can persist for a long time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% (4 log) inactivation can be achieved for FCV, and MNV in chocolate, the inactivation efficiency diminishes to approximately 90% (1 log) in pistachios and 70% (< 1 log) in cereal. AOP treatment could therefore be a good candidate for risk reduction of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.
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Sun, Y., D. T. Laird, and Y. C. Shieh. "Temperature-Dependent Survival of Hepatitis A Virus during Storage of Contaminated Onions." Applied and Environmental Microbiology 78, no. 14 (April 27, 2012): 4976–83. http://dx.doi.org/10.1128/aem.00402-12.
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ABSTRACTPre- or postharvest contamination of green onions by hepatitis A virus (HAV) has been linked to large numbers of food-borne illnesses. Understanding HAV survival in onions would assist in projecting the risk of the disease associated with their consumption. This study defined HAV inactivation rates in contaminated green onions contained in air-permeable, moisture-retaining high-density polyethylene packages that were stored at 3, 10, 14, 20, 21, 22, and 23°C. A protocol was established to recover HAV from whole green onions, with 31% as the average recovery by infectivity assay. Viruses in eluates were primarily analyzed by a 6-well plaque assay on FRhK-4 cells. Eight storage trials, including two trials at 3°C, were conducted, with 3 to 7 onion samples per sampling and 4 to 7 samplings per trial. Linear regression correlation (r2= 0.80 to 0.98) was observed between HAV survival and storage time for each of the 8 trials, held at specific temperatures. Increases in the storage temperature resulted in greater HAV inactivation rates, e.g., a reduction of 0.033 log PFU/day at 3.4 ± 0.3°C versus 0.185 log PFU/day at 23.4 ± 0.7°C. Thus, decimal reduction time (D) values of 30, 14, 11, and 5 days, respectively, were obtained for HAV in onions stored at 3, 10, 14, and 23°C. Further regression analysis determined that 1 degree Celsius increase would increase inactivation of HAV by 0.007 log PFU/day in onions (r2= 0.97). The data suggest that natural degradation of HAV in contaminated fresh produce is minimal and that a preventive strategy is critical to produce safety. The results are useful in predicting the risks associated with HAV contamination in fresh produce.
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Picard, Catherine, Isabelle Plard, Dominique Rongdaux-Gaida, and Jean-Claude Collin. "Detection of proteolysis in raw milk stored at low temperature by an inhibition ELISA." Journal of Dairy Research 61, no. 3 (August 1994): 395–404. http://dx.doi.org/10.1017/s0022029900030818.
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SummaryAn inhibition ELISA (enzyme-linked immunosorbent assay) was developed for the determination of caseinomacropeptide (CMP) in order to estimate the proteolysis of κ-casein due to the enzymes of psychrotrophic bacteria in bulk raw milk. The CMP present in milk was quantified specifically by an antibody. The limit of detection was ∽ 0·1 μg/ml and the CV was < 10%. This method was used to study the proteolytic activity of three strains of psychrotrophic Pseudomonas fluorescens in raw milk and to analyse different raw milk samples supplied by four dairy plants. The proteolytic activity for different strains of psychrotrophs and for different milk samples varied considerably, but no correlation was established between the level of microbial flora and κ-casein proteolysis. It is thus not possible to determine the extent of proteolysis from the bacterial count alone. However, by CMP determination in bulk raw milk samples after 6 d storage at 4°C, the mean κ-casein proteolysis was ∽ 4%. Among the milk samples analysed that contained < 107 cfu psychrotrophs/ml, 30% exhibited a proteolysis of κ-casein < 0·5%, i.e. < 5μg CMP/ml.
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Guedes, Liana B., Carlos L. Morais, Helen Fedor, Jessica Hicks, Bora Gurel, Jonathan Melamed, Peng Lee, et al. "Effect of Preanalytic Variables on an Automated PTEN Immunohistochemistry Assay for Prostate Cancer." Archives of Pathology & Laboratory Medicine 143, no. 3 (October 8, 2018): 338–48. http://dx.doi.org/10.5858/arpa.2018-0068-oa.
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Context.— Phosphatase and tensin homolog (PTEN) is a promising prognostic and potentially predictive biomarker in prostate cancer. Objective.— To assess the effects of preanalytic variables on an analytically validated and fully automated PTEN immunohistochemistry assay. Design.— PTEN immunohistochemistry was performed on Ventana immunostaining systems. In benign prostate tissues, immunostaining intensity across variable conditions was assessed by digital image analysis. In prostate tumor tissues, immunostaining was scored visually. Results.— Delay of fixation for 4 hours or longer at room temperature or 48 hours or longer at 4°C and duration of formalin fixation did not significantly alter immunostaining intensity. Intensity of staining was highest in 10% formalin compared with other fixatives. Tumor tissues with PTEN loss processed using protocols from 11 academic institutions were all evaluable and scored identically. PTEN immunostaining of needle biopsies where tissue blocks had been stored for less than 10 years was more frequently scored as nonevaluable compared with blocks that had been stored for 10 years or longer. This effect was less evident for radical prostatectomy specimens, where low rates of nonevaluable staining were seen for 23 years or more of storage. Storage of unstained slides for 5 years at room temperature prior to immunostaining resulted in equivalent scoring compared with freshly cut slides. Machine-to-machine variability assessed across 3 Ventana platforms and 2 institutions was negligible in 12 tumors, and platform-to-platform variability was also minor comparing Ventana and Leica instruments across 77 tumors (κ = 0.926). Conclusions.— Automated PTEN immunostaining is robust to most preanalytic variables in the prostate and may be performed on prostate tumor tissues subjected to a wide range of preanalytic conditions. These data may help guide assay development if PTEN becomes a key predictive biomarker.
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Barbaro, A., and S. Rożek. "Studies on luciferin-luciferase ATP assay in plants (etiolated wheat germs, and bean leaves)." Acta Societatis Botanicorum Poloniae 44, no. 3 (2015): 377–92. http://dx.doi.org/10.5586/asbp.1975.034.
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For ATP determination by the method of bioluminescence apparatus of home production was adapted from the equipment available in any isotope laboratory. The measurement error did not exceed 1.5 per cent. Methodical experiments concerned the choice of the extraction, fixation and storage methods of plant material for determination at the given moment of the amount of ATP in the tissues, unchanged by the analytical procedure. The highest ATP amounts were recovered by extraction with perchloric acid at high (25%) concentrations of the tissue in the homogenate. The best way of fixation of the material for later analyses was found to be freezing of ready extracts. Lyophilization and freezing of the plant material caused a several-fold decrease of the ATP level in the tissues. These results suggest the necessity of working in conditions of low temperature during the entire analytical procedure and strict observation of time limitation.
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Sahu, Shraddha, Shailendra Singh Shera, and Rathindra Mohan Banik. "Enhanced Reusability of Horseradish Peroxidase Immobilized onto Graphene Oxide/Magnetic Chitosan Beads for Cost Effective Cholesterol Oxidase Assay." Open Biotechnology Journal 13, no. 1 (August 30, 2019): 93–104. http://dx.doi.org/10.2174/1874070701913010093.
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Background: Horseradish Peroxidase (HRP) is an important biocatalyst extensively used in enzymatic reactions. Cholesterol oxidase (ChoX) is a commercially valuable enzyme used in the estimation of cholesterol in human serum. ChoX is an oxygen oxidoreductase class of enzyme which catalyzes the oxidation of cholesterol in the presence of O2, liberating hydrogen peroxide H2O2 as a by-product. HRP catalyzes the reduction of this H2O2 in the presence of a redox dye (chromophore), producing a pink colored Quinoneimine which can be measured spectrophotometrically. The use of soluble HRP makes this assay method expensive for each time use and the recovery of HRP is not possible. Objective: Our aim was to prepare the HRP immobilized beads having magnetic properties for the ease of separation and increasing the reusability of HRP for the low cost ChoX assay. Methods: In the present work, we prepared magnetic chitosan beads using chitosan-Fe2O3 nanoparticle blend coated with Graphene Oxide (GO), and subsequently activated with 2.5% glutaraldehyde (GA). Enzyme loaded beads were characterized by SEM, FTIR, and XRD analysis. Results: The immobilization efficiency was ~80% and the immobilized HRP retained 90% of its initial activity up to 12 times reuse. The pH and temperature optima were shifted from 6.5 and 50°C for soluble HRP to 7.0 and 55°C for the immobilized HRP, respectively. Storage stability of immobilized HRP was 93.72% and 60.97% after 30 and 60 days storage respectively, at 4°C. Conclusion: On the basis of the present study, the HRP loaded magnetic chitosan/graphene oxide beads could be used for low-cost ChoX assay at laboratory scale due to its enhanced reusability and stability.
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ZOU, YANG, WENHUI XIONG, YUANFA YANG, HUI AI, ZHIYONG ZOU, TIANRONG XIN, BIN XIA, and ZHIWEN ZOU. "Response of trehalose transporter gene in Aleuroglyphus ovatus (Troupeau) under low temperature stress." Zoosymposia 22 (November 30, 2022): 258. http://dx.doi.org/10.11646/zoosymposia.22.1.159.
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Globally distributed mite Aleuroglyphus ovatus is one of the dominant species of harmful mite in grain warehouses in China. It not only damages grains and edible fungi, but also causes various human diseases such as asthma. Temperature control and controlled atmosphere are two mature and widely used green grain storage technologies. In order to explore the mechanism of low temperature in the prevention and control of A. ovatus, this paper accurately obtained the half-lethal temperature (LLt50) and 99% lethal temperature (LLt99), 8.878 °C and -8.520 °C, respectively, and the half-lethal time (LLT50) and 99% lethal time (LLT99), 2.225 h and 26.979 h, respectively, of A. ovatus through low temperature exposure experiments. Enzyme-linked immuno sorbent assay (ELISA) showed that with the decrease of temperature (16 °C to 4 °C), the trehalose transporter (Tret) content and trehalose concentration increased, while the glucose concentration decreased. When it was lower than 8 °C, Tret protein content began to decrease, trehalose content decreased, and glucose content increased after 4 °C. In the meantime, the content of trehalose transporter in egg stage was significantly higher than that in other stages (P <0.05). Then, the full-length of AoTret1-1 and AoTret1-2 genes of A. ovatus, 1,754 bp and 1,727 bp, was obtained by RACE technique. The mRNA expression levels of AoTret1-1 and AoTret1-2 under low temperature stress and different developmental stages were detected by qRT-PCR technique. Both AoTret1-1 and AoTret1-2 genes had the specificity of development stage, and the expression level of two AoTret1 genes in the egg and adult stages were significantly higher than those in other stages. After adults of A. ovatus were treated with low temperatures (0 °C, 4 °C, 8 °C, 12 °C, and 16 °C) for 3 h, the expression of AoTret1-1 and AoTret1-2 were significantly higher than those in the control group (28 °C), and the highest gene expression levels of AoTret1-1 and AoTret1-2 appeared at 8 °C. Our study showed that AoTret could play an important role in resisting low temperature stress in A. ovatus. To sum up, A. ovatus is a freeze-avoiding species, and its ability to withstand extreme low temperature is weak. It could significantly increase the contents of Tret, and accumulate trehalose in response to low temperature stress. Its two Tret genes were upregulated significantly by low temperature stress, which indicated that Tret was a potential specific target gene for A. ovatus control.
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Gavara, Jorge, Tomás Cabello, Juan Ramón Gallego, Estrella Hernández-Suarez, and Ana Piedra-Buena Díaz. "Evaluation of the Egg Predator Blattisocius tarsalis (Mesostigmata: Blattisociidae) for the Biological Control of the Potato Tuber Moth Tecia solanivora under Storage Conditions." Agriculture 12, no. 7 (June 24, 2022): 920. http://dx.doi.org/10.3390/agriculture12070920.
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Tecia solanivora is the most prevalent pest causing damage to potato crops in fields in the Canary Islands, but even more so in the postharvest storage period. However, currently, there are no authorised chemical insecticides for potato storage facilities. Analysis of the viability of the predator mite Blattisocius tarsalis as a biological control agent for this moth was carried out. A study of the temperature effect showed B. tarsalis maintains predatory capacity in the range of 10–27 °C. Though predatory activity increases with temperature, no differences in mortality rates were observed between 10 and 20 °C (33.52 ± 2.44 and 40.14 ± 3.54% efficacy rate, respectively), nor between 25 and 27 °C (59.26 ± 4.59 and 75.19 ± 4.64% efficacy rate, respectively). Under microcosm conditions, at low pest infestation (10 eggs), B. tarsalis achieved the highest mortality of eggs at a density of 5 mites, with an efficacy rate of 91.67 ± 8.33%. At high infestation levels (50 eggs), maximum mortality was achieved with a density of 10 mites and efficacy of 98.52 ± 1.48%. The choice-assay showed no preference of B. tarsalis between T. solanivora and Phthorimaea operculella, suggesting this mite could be useful in mixed infestations of potato moths. The results show B. tarsalis is a very good candidate as a control agent in storage conditions and even in mixed infestations of T. solanivora and P. operculella.
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Höglund, Katja, Hanna Palmqvist, Sara Ringmark, and Anna Svensson. "Quantification of normetanephrine in canine urine using ELISA: evaluation of factors affecting results." Journal of Veterinary Diagnostic Investigation 34, no. 1 (October 26, 2021): 28–35. http://dx.doi.org/10.1177/10406387211052984.
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Catecholamine release increases in dogs with pheochromocytomas and in situations of stress. Although plasma catecholamines degrade rapidly, their metabolites, normetanephrine (NME) and metanephrine (ME), are stable in acidified urine. Our aim was to verify a human urine ELISA kit for the quantification of NME and ME in canine urine and to determine the effects on metabolite stability of sampling time (morning or midday) and day (ordinary or day spent in a clinic). We analyzed 179 urine samples from 17 healthy dogs. For NME, the mean intra-assay CV was 6.0% for all samples and 4.3% for the canine control; inter-assay CVs were 3.3, 3.8, and 12% for high and low concentration human urine positive controls supplied in the ELISA kit and a positive canine control, respectively; spike-recovery was 90–101%. For ME, mean intra-assay CV was 6.5% for samples and 9.0% for the canine control; inter-assay CVs were 12.7, 7.2, and 22.5% for high and low concentration human urine positive controls supplied in the ELISA kit and a positive canine control, respectively; spike-recovery was 85–89%. Dilution recovery was unsatisfactory for both metabolites. Based on our verification results, NME was selected for remaining analyses. We found no effect on NME concentrations of acidification or room temperature storage for up to 24 h. The NME:creatinine ratio was higher after the first of 3 clinic days compared to the same morning (111.2 ± 5.5 vs. 82.9 ± 5.3; p < 0.0001), but not on the other days. NME verification results were generally superior to ME. Dilution studies were unsatisfactory for both metabolites. Given that NME was stable without acidification at room temperature, urine samples can be collected at home. The clinic environment can cause higher NME:creatinine ratios, especially in unaccustomed dogs.
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Zhang, Mengxue, Yanna Shi, Zimeng Liu, Yijin Zhang, Xueren Yin, Zihao Liang, Yiqing Huang, Donald Grierson, and Kunsong Chen. "An EjbHLH14-EjHB1-EjPRX12 module is involved in methyl jasmonate alleviation of chilling-induced lignin deposition in loquat fruit." Journal of Experimental Botany 73, no. 5 (December 5, 2021): 1668–82. http://dx.doi.org/10.1093/jxb/erab511.
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Abstract Loquat fruit are susceptible to chilling injuries induced by postharvest storage at low temperature. The major symptoms are increased lignin content and flesh firmness, which cause a leathery texture. Pretreatment with methyl jasmonate (MeJA) can alleviate this low-temperature-induced lignification, but the mechanism is not understood. In this study, we characterized a novel class III peroxidase, EjPRX12, and studied its relationship to lignification. Transcript levels of EjPRX12 were attenuated following MeJA pretreatment, consistent with the reduced lignin content in fruit. In vitro enzyme activity assay indicated that EjPRX12 polymerized sinapyl alcohol, and overexpression of EjPRX12 in Arabidopsis promoted lignin accumulation, indicating that it plays a functional role in lignin polymerization. We also identified an HD-ZIP transcription factor, EjHB1, repressed by MeJA pretreatment, which directly bound to and significantly activated the EjPRX12 promoter. Overexpression of EjHB1 in Arabidopsis promoted lignin accumulation with induced expression of lignin-related genes, especially AtPRX64. Furthermore, a JAZ-interacting repressor, EjbHLH14, was characterized, and it is proposed that MeJA pretreatment caused EjbHLH14 to be released to repress the expression of EjHB1. These results identified a novel regulatory pathway involving EjbHLH14-EjHB1-EjPRX12 and revealed the molecular mechanism whereby MeJA alleviated lignification of loquat fruit at low temperature.
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Reinhardt, Brian, Robert Taylor, Colin Dawkins, Taylor Banks, Nora Watson, Appavu Sundaram, Daniel Ewing, and Janine Ruth Danko. "The use of dried blood spot cards to assess serologic responses of individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster." PLOS ONE 17, no. 3 (March 24, 2022): e0265813. http://dx.doi.org/10.1371/journal.pone.0265813.
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Traditional blood sampling by venipuncture is cumbersome and relatively expensive. Dried blood spot (DBS) sampling is desirable because of its ease of sample collection, transportation and storage. It has been used in clinical diagnosis but not been thoroughly studied for the potential use to assess the immune status of individuals following natural infection or preventive vaccination. The goal of this study was to compare DBS to traditional blood samplings in detection of antibodies in individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster. Enzyme linked immunosorbent assay (ELISA) was used to test DBS eluates and serum samples for antibodies against measles, varicella, tetanus and hepatitis A. Sensitivities, specificities, and correlation coefficients were evaluated to compare optical density (OD) values of paired serum and DBS samples. The long-term stability of DBS samples at different temperatures was assessed using simulated immune measles blood. DBS OD was highly correlated with serum OD for antibodies to measles (r = 0.93), varicella (r = 0.82), and tetanus (r = 0.91). Sensitivities of DBS OD ranged from 86–99% and specificities ranged from 96–100% using cut-offs established by each assay. By contrast, the hepatitis A data showed a low sensitivity (31%) and weak correlation (r = 0.14) between DBS and serum samples. Antibody titers in serum samples for anti-influenza A (H1N1 and H3N1) failed to correlate in DBS eluates in HAI and MN assays. DBS samples were stable for 4 weeks when stored at room temperature and for 6 months at 4°C. DBS sampling was sensitive, specific, and highly correlated with traditional venipuncture sampling in detection of antibodies against measles, tetanus and varicella zoster, but not hepatitis A and influenza. Thus, the success of using DBS sampling to assess the antibody levels in immunized individuals may be dependent on the pathogens and the development of the assay used.
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Vincent, Anne-Marie, David Lillicrap, Angie Tuttle, Angélique Hofer, Anik Cormier, Jean St-Louis, and Georges E. Rivard. "Assay of Factor VIII Antibodies by ELISA Using Plasma Specimens Dried On Filter Paper and Stored at Room Temperature." Blood 114, no. 22 (November 20, 2009): 3479. http://dx.doi.org/10.1182/blood.v114.22.3479.3479.
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Abstract Abstract 3479 Poster Board III-416 Introduction ELISA assays have been proposed as a complement to the Bethesda assay for detection and follow-up of factor VIII (FVIII) antibodies in subjects with hemophilia. The Bethesda assay has several drawbacks. Most importantly, the Bethesda assay would not detect non-inhibitory antibodies, even though these could be responsible for low in vivo recovery of FVIII and /or a pharmacokinetic pattern suggestive of rapid clearance of FVIII. ELISA assays for detecting antibodies to FVIII are not routinely performed in most hospital laboratories and as such, specimens need to be transported to specialized laboratories for processing. Transportation of plasma specimens frozen on dry ice, however, is both costly and cumbersome. Room temperature storage of whole blood and serum specimens adsorbed and dried onto filter paper has been shown to be a convenient and reliable alternative to frozen whole blood and serum samples for various analyses. This study was undertaken to assess whether FVIII antibodies from haemophilic plasma would display similar stability when stored adsorbed onto filter paper at room temperature for 1 month or on plasma specimens stored frozen. Stability was assessed by comparing results of ELISA assays. Methods two hundred and thirteen frozen (at -80°C) plasma samples from patients with or without known FVIII inhibitors were tested. Samples came from 97 congenital haemophilic subjects and 5 subjects with acquired haemophilia. The samples were tested with a previously reported ELISA assay (Haemophilia 2009; 15: 374-6) with minor modifications. The coating antigens were two therapeutic preparations of recombinant FVIII: the full length FVIII preparation Helixate® FS, and the B-domain deleted FVIII Xyntha®. Five dilutions of plasma from a subject with congenital severe hemophilia A known to have a high Bethesda titer was put on all plates as positive control. Six normal plasmas were used on all plates as negative controls. Mean and standard deviation of optical densities were calculated for negative controls. Mean was subtracted from optical density of each test plasma. The resulting value was divided by the value of one standard deviation of negative controls to generate the number of standard deviations for test plasmas. All plasmas were assayed in duplicate. The numbers of standard deviations were compared between frozen samples and samples dried on filter papers. Results The correlation between the numbers of standard deviations obtained with frozen specimens and with specimens dried on filter paper was excellent for both therapeutic preparations of recombinant FVIII, going from R= 0.91 to R= 0.99. Conclusion FVIII antibodies tested by ELISA using plasma dried on filter paper for one month at room temperature or plasma stored at -80°C give comparable results. Disclosures: No relevant conflicts of interest to declare.
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Tian, Jiaxin, Yuhang Wang, Jinling Li, Yonggang Chen, Jiarui Qinchen, Fanghui Deng, Xiaoyang Wu, et al. "Structural characteristics and physicochemical properties of fresh-water fish gelatins with different molecular weights and their potential application to food capsule film fabrication." Materials Express 10, no. 3 (March 1, 2020): 419–29. http://dx.doi.org/10.1166/mex.2020.1676.
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This work is aimed to investigate the effects of molecular weights on physicochemical properties of fish gelatins and their potential application to food capsule film fabrication. Firstly, high/medium/low component fish gelatins (HCG/MCG/LCG) were obtained by ultrafiltration. Physicochemical property assay results showed that high molecular weight content of gelatin contributed to the increase in gelling strength, viscosity, melting point, and denaturation temperature due to extensive inter–intra molecular interactions. Meanwhile, parameters (temperature, weight ratio, and drying time) had been comprehensively investigated to determine the effects of three molecular weights of gelatins on capsule film manufacture. MCG-derived capsule film was found to achieve good balance among tensile strength, elongation at break, and dissolution rate constant. Furthermore, 90-day acceleration storage stability experiment suggested that MCG showed an appropriate ɛ-amino acid residue content and crosslink density. This work provides a comprehensive insight into the effect of molecular weights on physicochemical properties of fish gelatins and their application in food capsule film manufacture.
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Carvalho, Juliana Vanir De Souza, Eduardo De Sá Mendonça, Newton La Scala, César Reis, Efrain Lázaro Reis, and Carlos E. G. R. Schaefer. "CO2-C losses and carbon quality of selected Maritime Antarctic soils." Antarctic Science 25, no. 1 (October 3, 2012): 11–18. http://dx.doi.org/10.1017/s0954102012000648.
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AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.
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Habtu, Danni Y., Neal Chamberlain, Elyse Curry, and Ryan Hart. "1194. Identification and Characterization of Extracellular Inducers of Persistence in Staphylococcus epidermidis and Staphylococcus aureus." Open Forum Infectious Diseases 7, Supplement_1 (October 1, 2020): S619. http://dx.doi.org/10.1093/ofid/ofaa439.1379.
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Abstract Background This study describes the identification and partial characterization of persistence inducing factors (PIF) from Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). Persistence is an epigenetic process that results in tolerance of bacterial cells to antibiotic treatment, which can result in chronic human infections. Methods Others have demonstrated a significant increase in persister numbers during mid-log phase. Inducers of this mid-log increase have yet to be identified in staphylococci. Optical density at 600 nm (OD600) was used instead of time to determine when persister numbers increased during logarithmic growth. Concentrated culture filtrates (CCF) from S. epidermidis RP62A and S. aureus SH1000 were obtained at various OD600’s and following incubation at 16 h. The CCF’s were used to develop a persistence inducing factor (PIF) assay. The PIF assay was used to partially characterize PIF from S. epidermidis RP62A and S. aureus SH1000 for relative molecular weight, temperature and protease sensitivity and inter-species communications. Results Optimal OD600’s for the S. epidermidis RP62A and S. aureus SH1000 PIF assays were 2.0 and 0.5, respectively. The highest PIF activity for both species was from CCF following incubation overnight (16 h). S. epidermidis RP62A’s PIF activity was decreased by storage at 4o C (2 weeks or longer) but not following incubation at 20o C (16 h), 37o C (1 h) or 100o C (15 min). S. aureus SH1000’s PIF activity was decreased following storage at 4o C (2 week or longer) and after boiling at 100oC for 5 min but not after incubation at 37o C (1 h). PIF activity from both species was less than 3,000 Mrr. Proteinase-K treatment of S. aureus SH1000 PIF decreased activity but did not decrease PIF activity of S. epidermidis RP62A. PIF from S. epidermidis RP62A did not increase persister numbers when used to treat S. aureus SH1000 cells nor did PIF from S. aureus SH1000 increase persister numbers in S. epidermidis RP62A cells. Conclusion Previous attempts to discover PIF’s for staphylococcal species were unsuccessful due to the time-based means used to identify mid-log. Both staphylococcal species appear to produce unique, extracellular, low-molecular-weight inducers of persistence (PIF) when assayed using an OD600-based PIF assay. Disclosures All Authors: No reported disclosures
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MORMANN, SASCHA, CATHRIN HEIßENBERG, JENS PFANNEBECKER, and BARBARA BECKER. "Tenacity of Human Norovirus and the Surrogates Feline Calicivirus and Murine Norovirus during Long-Term Storage on Common Nonporous Food Contact Surfaces." Journal of Food Protection 78, no. 1 (January 1, 2015): 224–29. http://dx.doi.org/10.4315/0362-028x.jfp-14-165.
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The transfer of human norovirus (hNV) to food via contaminated surfaces is highly probable during food production, processing, and preparation. In this study, the tenacity of hNV and its cultivable surrogates feline calicivirus (FCV) and murine norovirus (MNV) on two common nonporous surface materials at two storage temperatures was directly compared. Virus titer reduction on artificially inoculated stainless steel and plastic carriers was monitored for 70 days at room temperature and at 7°C. Viruses were recovered at various time points by elution. Genomes from intact capsids (hNV, FCV, and MNV) were quantified with real-time reverse transcription (RT) PCR, and infectivity (FCV and MNV) was assessed with plaque assay. RNase treatment before RNA extraction was used to eliminate exposed RNA and to assess capsid integrity. No significant differences in titer reduction were found between materials (stainless steel or plastic) with the plaque assay or the real-time quantitative RT-PCR. At room temperature, infectious FCV and MNV were detected for 7 days. Titers of intact hNV, FCV, and MNV capsids dropped gradually and were still detectable after 70 days with a loss of 3 to 4 log units. At 7°C, the viruses were considerably more stable than they were at room temperature. Although only MNV infectivity was unchanged after 70 days, the numbers of intact capsids (hNV, FCV, and MNV) were stable with less than a 1-log reduction. The results indicate that hNV persists on food contact surfaces and seems to remain infective for weeks. MNV appears to be more stable than FCV at 7°C, and thus is the most suitable surrogate for hNV under dry conditions. Although a perfect quantitative correlation between intact capsids and infective particles was not obtained, real-time quantitative RT-PCR provided qualitative data about hNV inactivation characteristics. The results of this comparative study might support future efforts in assessment of foodborne virus risk and food safety.
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Mwau, Matilu, Sven Schaffer, Humphrey Kimani, Purity Kasiano, Francis Ogolla, Elizabeth Ajema, Scriven Adoyo, Ednah Nyairo, Norah Saleri, and Sangeetha Vijaysri Nair. "Comparison of the performance of Aptima HIV-1 Quant Dx Assay with Abbott RealTime HIV Assay for viral load monitoring using plasma and Dried Blood Spots collected in Kenya." PLOS ONE 17, no. 8 (August 22, 2022): e0269838. http://dx.doi.org/10.1371/journal.pone.0269838.
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Introduction HIV-1 viral Load (VL) testing is recommended for the monitoring of antiretroviral treatment. Dried Blood Spots (DBS) are an effective sample type in resource limited settings, where safe phlebotomy and reliable shipping are hard to guarantee. In HIV high burden countries, high throughput assays can improve access to testing services. The Hologic Aptima HIV-1 Quant Dx Assay (Aptima Assay) is a high throughput assay that runs on the CE-IVD approved Panther platform. The objectives of this study were to assess the performance characteristics of Aptima for VL monitoring using plasma and venous DBS specimens and to determine the stability of HIV-1 RNA in DBS. Materials and methods This was a cross-sectional study of 2227 HIV infected adults visiting health facilities in Nairobi and Busia, Kenya. Each provided a venous blood sample; plasma was prepared from 1312 samples while paired DBS samples and plasma were prepared from the remaining 915 samples. The agreement between the Aptima assay and the Abbott RealTime HIV-1 Assay (Abbott RT) was analysed by comparing the HIV-1 VL in both assays at the medical decision point of 1000 copies/mL. To assess stability of HIV-1 RNA in DBS, VL in DBS spotted on day 0 were compared with that from the same DBS card after 21 days of storage at room temperature. Results Overall, 436 plasma samples had quantifiable results in both Aptima and Abbott RT. The agreement between the two assays at 1000 copies/mL was 97.48% with a Pearson’s correlation coefficient (r) of 0.9589 and gave a mean bias of 0.33 log copies/mL on Bland-Altman analysis. For fresh DBS, the agreement in both assays was 94.64% at 1000 copies/mL, with an r of 0.8692 and a mean bias of 0.35 log copies/mL. The overall agreement between DBS tested in Aptima on day 0 versus day 21 was 95.71%, with a mean bias of -0.154. Conclusion The Aptima HIV-1 Quant Dx assay is an accurate test for VL monitoring of HIV-1 using DBS and plasma sample types in Kenya.
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Zawani, Che Jaafar, Mahmud Ab Rashid Nor-Khaizura, Nor Ainy Mahyudin, Mohammad Rashedi Ismail-Fitry, and Nilesh Prakash Nirmal. "Microbiological and Sensorial Quality of Beef Meat (Longissimus dorsi) Marinated with Cinnamon Extract and Stored at Various Temperatures." Foods 11, no. 24 (December 8, 2022): 3971. http://dx.doi.org/10.3390/foods11243971.
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Meat spoilage caused by temperature abuse is a major problem for producers, retailers, and consumers that can generate large economic losses to industries. Microbial growth of Pseudomonas spp. is the main source of spoilage during storage. Cinnamon has antimicrobial properties that may potentially be used to reduce the spoilage caused by Pseudomonas. The objectives of this study were to determine the inhibitory effect of cinnamon extract (CE) against Pseudomonas aeruginosa (ATCC 27853) and evaluate the treatment of CE on meat quality during different storage temperatures (5 °C, 10 °C, 15 °C, and 25 °C). The anti-Pseudomonas result showed that 100% (w/v) CE concentration produced a 13.50 mm zone of inhibition in a disc diffusion assay. The minimum inhibitor concentration (MIC) of CE was noted at 25% (v/v), whereas the minimum bactericidal concentration (MBC) value was observed at 50% (v/v) concentration of CE. The time-kill showed the growth of P. aeruginosa decreased from 7.64 to 5.39 log CFU/mL at MIC concentration. Total phenolic content and IC50 value of the cinnamon extract was expressed as 6.72 ± 0.87 mg GAE/g extract and 0.15 mg/mL, respectively. When the meat was marinated with 50% (v/v) CE and stored at various temperatures, the total viable count (TVC) and growth of Pseudomonas spp. were lowered as compared to the control sample. However, the reduction in microbial count in all samples was influenced by the storage temperature, where the lowered microbial count was noted in the sample treated with CE and stored at 5 and 10 °C for 48 h. The pH of meat treated with or without CE ranged from pH 5.74 to 6.48. The sensory attributes of colour, texture, and overall acceptability have a significant difference, except for odour, between marinated meat and control. The results indicate that the use of cinnamon extract as the marination agent for meat could reduce the growth of Pseudomonas spp. and therefore assist in extending the shelf life of meat at 5 and 10 °C storage temperatures.
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Shirzad, Habib, Abolfazl Alirezalu, Kazem Alirezalu, Milad Yaghoubi, Bahareh Ghorbani, Mirian Pateiro, and José M. Lorenzo. "Effect of Aloysia citrodora Essential Oil on Biochemicals, Antioxidant Characteristics, and Shelf Life of Strawberry Fruit during Storage." Metabolites 11, no. 5 (April 21, 2021): 256. http://dx.doi.org/10.3390/metabo11050256.
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Strawberry fruits are highly susceptible to cold burning, resulting in low storage periods at low temperatures. Plant extracts or essential oils (EOs) can potentially be used as preservatives in fruits throughout the refrigerated period. In the present study, the biochemicals, antioxidant characteristics, and shelf life of treated strawberries with Aloysia citrodora essential oil (ACEOs) were evaluated during keeping time. The treatments were produced as follows: T1, control; T2, 250 ppm ACEOs; T3, 500 ppm ACEOs; and T4, 750 ppm ACEOs. Total soluble solids (TSS), weight loss, titratable acidity (TA), antioxidant activity (DPPH assay), total phenolic (TPC), flavonoid and anthocyanin contents (TFC), and enzymes activity (peroxidase and ascorbate peroxidase) were evaluated during the refrigerated period (5 °C with relative humidity of 85–90% for 20 days). The results revealed that weight loss and TA were reduced in all treatments during storage, being that the rates were lower in samples treated with ACEOs. TPC, TFC, TSS, antioxidant, and enzymes activity were higher in treated fruits than control.
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Whaley, David, Kimia Damyar, Rafal P. Witek, Alan Mendoza, Michael Alexander, and Jonathan RT Lakey. "Cryopreservation: An Overview of Principles and Cell-Specific Considerations." Cell Transplantation 30 (January 1, 2021): 096368972199961. http://dx.doi.org/10.1177/0963689721999617.
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The origins of low-temperature tissue storage research date back to the late 1800s. Over half a century later, osmotic stress was revealed to be a main contributor to cell death during cryopreservation. Consequently, the addition of cryoprotective agents (CPAs) such as dimethyl sulfoxide (DMSO), glycerol (GLY), ethylene glycol (EG), or propylene glycol (PG), although toxic to cells at high concentrations, was identified as a necessary step to protect against rampant cell death during cryopreservation. In addition to osmotic stress, cooling and thawing rates were also shown to have significant influence on cell survival during low temperature storage. In general, successful low-temperature cell preservation consists of the addition of a CPA (commonly 10% DMSO), alone or in combination with additional permeating or non-permeating agents, cooling rates of approximately 1ºC/min, and storage in either liquid or vapor phase nitrogen. In addition to general considerations, cell-specific recommendations for hepatocytes, pancreatic islets, sperm, oocytes, and stem cells should be observed to maximize yields. For example, rapid cooling is associated with better cryopreservation outcomes for oocytes, pancreatic islets, and embryonic stem cells while slow cooling is recommended for cryopreservation of hepatocytes, hematopoietic stem cells, and mesenchymal stem cells. Yields can be further maximized by implementing additional pre-cryo steps such as: pre-incubation with glucose and anti-oxidants, alginate encapsulation, and selecting cells within an optimal age range and functional ability. Finally, viability and functional assays are critical steps in determining the quality of the cells post-thaw and improving the efficiency of the current cryopreservation methods.
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Spanò, Carmelina, Stefania Bottega, Roberto Lorenzi, and Isa Grilli. "Ageing in embryos from wheat grains stored at different temperatures: oxidative stress and antioxidant response." Functional Plant Biology 38, no. 7 (2011): 624. http://dx.doi.org/10.1071/fp11046.
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In the present work we studied oxidative stress as an important cause of seed deterioration during ageing in embryos from durum wheat grains stored at room temperature and at low temperature (10°C). The protective role of low temperature on seed viability was confirmed. The increase of hydrogen peroxide content during dry storage was strongly correlated with the decrease of germinability. Ascorbate and glutathione showed a good correlation with grain germinability and significantly increased upon imbibition, in particular in embryos from viable grains. Ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX) and catalase (CAT) were studied quantitatively (enzymatic assays). APX, GR, and GPX were also studied qualitatively by native PAGE. The enzymes were active in dry, still viable, embryos whereas no activity was detected in non-viable embryos. With the exception of APX, all enzymatic activities decreased upon imbibition. The study of grains stored in different conditions indicated a negative correlation between the efficiency of the antioxidant enzymatic machinery and the age of the grain. The differences detected in differently stored materials confirmed that both germination parameters and the length of storage period are important in determining grain condition.
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Engler, Randall. "Heraeus cytomat® 6000 Series Incubators and Storage Systems from Kendro Laboratory Products." JALA: Journal of the Association for Laboratory Automation 5, no. 2 (April 2000): 38–41. http://dx.doi.org/10.1016/s1535-5535-04-00060-7.
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There are a number of cases in high throughput screening systems where a controlled environment is desired. These include incubation periods for cell-based assays, incubation for protein detection assays such as ELISA or fluorescence assays, and branching assays for mRNA detection. In addition, as the density of wells in microplates increases and well volumes become smaller, evaporation becomes a concern in all assays. The cytomat® 6000 is a robot accessible, automated CO2 incubator used for cell-based High Throughput Screening systems. The incubator provides superior environmental conditions, due to the unique access door at the back of the instrument, the PlateShuttle (see Figure 3 ). This small access opening insures that the environment inside the system (temperature, humidity and CO2) is undisturbed as microplates are accessed ( Figure 2 ). The system provides high speed, random (bar-coded) access to all microplate formats for 24, 96, 384 and 1536 well microplates (up to 261-microplate capacity). Other cytomat configurations offer refrigerated and low humidity environments.
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Lee, Su Jin, Jiyeon Si, Hyun Sun Yun, and GwangPyo Ko. "Effect of Temperature and Relative Humidity on the Survival of Foodborne Viruses during Food Storage." Applied and Environmental Microbiology 81, no. 6 (January 9, 2015): 2075–81. http://dx.doi.org/10.1128/aem.04093-14.
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ABSTRACTMillions of people suffer from foodborne diseases throughout the world every year, and the importance of food safety has grown worldwide in recent years. The aim of this study was to investigate the survival of hepatitis A virus (HAV) and viral surrogates of human norovirus (HuNoV) (bacteriophage MS2 and murine norovirus [MNV]) in food over time. HAV, MNV, and MS2 were inoculated onto either the digestive gland of oysters or the surface of fresh peppers, and their survival on these food matrices was measured under various temperature (4°C, 15°C, 25°C, and 40°C) and relative humidity (RH) (50% and 70%) conditions. Inoculated viruses were recovered from food samples and quantified by a plaque assay at predetermined time points over 2 weeks (0, 1, 3, 7, 10, and 14 days). Virus survival was influenced primarily by temperature. On peppers at 40°C and at 50% RH, >4- and 6-log reductions of MNV and HAV, respectively, occurred within 1 day. All three viruses survived better on oysters. In addition, HAV survived better at 70% RH than at 50% RH. The survival data for HAV, MS2, and MNV were fit to three different mathematical models (linear, Weibull, and biphasic models). Among them, the biphasic model was optimum in terms of goodness of fit. The results of this study suggest that major foodborne viruses such as HAV and HuNoV can survive over prolonged periods of time with a limited reduction in numbers. Because a persistence of foodborne virus on contaminated foods was observed, precautionary preventive measures should be performed.
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Tucker, Luke J., Christine S. Grant, Malley A. Gautreaux, Dhanush L. Amarasekara, Nicholas C. Fitzkee, Amol V. Janorkar, Anandavalli Varadarajan, Santanu Kundu, and Lauren B. Priddy. "Physicochemical and Antimicrobial Properties of Thermosensitive Chitosan Hydrogel Loaded with Fosfomycin." Marine Drugs 19, no. 3 (March 6, 2021): 144. http://dx.doi.org/10.3390/md19030144.
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Thermosensitive chitosan hydrogels—renewable, biocompatible materials—have many applications as injectable biomaterials for localized drug delivery in the treatment of a variety of diseases. To combat infections such as Staphylococcus aureus osteomyelitis, localized antibiotic delivery would allow for higher doses at the site of infection without the risks associated with traditional antibiotic regimens. Fosfomycin, a small antibiotic in its own class, was loaded into a chitosan hydrogel system with varied beta-glycerol phosphate (β-GP) and fosfomycin (FOS) concentrations. The purpose of this study was to elucidate the interactions between FOS and chitosan hydrogel. The Kirby Bauer assay revealed an unexpected concentration-dependent inhibition of S. aureus, with reduced efficacy at the high FOS concentration but only at the low β-GP concentration. No effect of FOS concentration was observed for the planktonic assay. Rheological testing revealed that increasing β-GP concentration increased the storage modulus while decreasing gelation temperature. NMR showed that FOS was removed from the liquid portion of the hydrogel by reaction over 12 h. SEM and FTIR confirmed gels degraded and released organophosphates over 5 days. This work provides insight into the physicochemical interactions between fosfomycin and chitosan hydrogel systems and informs selection of biomaterial components for improving infection treatment.
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Wang, Jiong, Dongmei Li, Alexander Wiltse, Jason Emo, Shannon P. Hilchey, and Martin S. Zand. "Application of volumetric absorptive microsampling (VAMS) to measure multidimensional anti-influenza IgG antibodies by the mPlex-Flu assay." Journal of Clinical and Translational Science 3, no. 6 (September 26, 2019): 332–43. http://dx.doi.org/10.1017/cts.2019.410.
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AbstractIntroduction: Recently, volumetric absorptive microsampling (VAMS) has been used for accurate sampling of a fixed peripheral blood volume (10 µL) on a volumetric swab, and long-term sample storage. The mPlex-Flu assay is a novel, high-throughput assay that simultaneously measures the concentration of antibodies against the hemagglutinin (HA) proteins from multiple influenza virus strains with ≤5 µL of serum. Here we describe combining these two methods to measure multidimensional anti-influenza IgG activity in whole blood samples collected by a finger stick and VAMS, with correction for serum volume based on simultaneous hemoglobin measurement. Methods: We compared capillary blood samples obtained from a finger stick using a VAMS device with serum samples collected by traditional phlebotomy from 20 subjects, with the influenza antibody profiles measured by the mPlex-Flu assay. Results: We found that results with the two sampling methods were highly correlated within subjects and across all influenza strains (mean R2 = 0.9470). Adjustment for serum volume, based on hemaglobin measurement, was used to estimate serum volume of samples and improved the accuracy. IgG measurements were stable over 3 weeks when VAMS samples were stored at room temperature or transported using a variety of shipping methods. Additionally, when volunteers performed finger-stick VAMS at-home by themselves, the comparison results of anti-HA antibody concentrations were highly consistent with sampling performed by study personnel on-site (R2 = 0.9496). Conclusions: This novel approach can provide a simple, accurate, and low-cost means for monitoring the IgG anti-influenza HA antibody responses in large population studies and clinical trials.
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Lei, Rongwei, Hufsa Arain, Maryam Obaid, Nivriti Sabhnani, and Chandra Mohan. "Ultra-Sensitive and Semi-Quantitative Vertical Flow Assay for the Rapid Detection of Interleukin-6 in Inflammatory Diseases." Biosensors 12, no. 9 (September 14, 2022): 756. http://dx.doi.org/10.3390/bios12090756.
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The inflammation biomarker Interleukin 6 (IL-6) exhibits a concentration of less than 7 pg/mL in healthy serum but increases 10–100-fold when inflammation occurs. Increased serum IL-6 has been reported in chronic diseases such as rheumatoid arthritis (RA), as well as in life-threatening acute illnesses such as sepsis and cytokine release syndrome (CRS). This work seeks to meet the demand for rapid detection of serum IL-6 both for rapid monitoring of chronic diseases and for triaging patients with acute illnesses. Following the optimization of several types of gold nanoparticles, membrane pore sizes, and buffer systems, an ultra-sensitive vertical flow assay (VFA) was engineered, allowing the detection of recombinant IL-6 in spiked buffer with a limit of detection (LoD) of 10 pg/mL and a reportable range of 10–10,000 pg/mL with a 15-min assay time. The detection of IL-6 in spiked pooled healthy serum exhibited an LoD of 3.2 pg/mL and a reportable range of 10–10,000 pg/mL. The VFA’s stability was demonstrated over 1-day, two-week, four-week, and six-week storage durations at room temperature. The inter-operator CV and intra-operator CV were determined to be 14.3% and 15.2%, respectively. Three reference zones, high, low, and blank, were introduced into the cartridge to facilitate on-site semi-quantitative measurements across a 6-point semi-quantitative range. Finally, the performance of the IL-6 VFA was validated using 20 RA and 20 healthy control (HC) clinical serum samples, using ELISA as the gold standard platform. The ultra-sensitive, rapid IL-6 VFA could potentially be used to triage patients for intensive care, treatment adjustments, or for monitoring disease activity in inflammatory conditions.
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PEREZ, KEILA L., M. JAHANGIR ALAM, ALEJANDRO CASTILLO, and T. MATTHEW TAYLOR. "Antibiotic Resistance and Growth of the Emergent Pathogen Escherichia albertii on Raw Ground Beef Stored under Refrigeration, Abuse, and Physiological Temperature." Journal of Food Protection 76, no. 1 (January 1, 2013): 124–28. http://dx.doi.org/10.4315/0362-028x.jfp-12-277.
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Escherichia albertii is an emerging gram-negative facultative rod that has been implicated in multiple cases of human diarrheal disease, particularly in young children. When biochemical and other typing methods have been used, this organism has often been misidentified due to similarities with other members of the family Enterobacteriaceae. Isolates have been reported to be capable of producing attachment and effacement lesions via the synthesis of intimin, cytolethal distending toxin, and a variant form of Shiga toxin. The purposes of this study were to characterize the antibiotic resistance characteristics and the growth of individual strains of E. albertii on raw ground beef at different storage temperatures. Nalidixic acid–resistant strains of E. albertii were inoculated onto raw ground beef to a target of 4.0 log CFU/g, and samples were then aerobically incubated at 5, 22, or 35°C for various time periods prior to microbiological enumeration of the pathogen on lactose-free MacConkey agar containing 50 mg of nalidixic acid per liter and 0.5% l-rhamnose. Antibiotic resistance was determined using a broth microdilution assay. E. albertii did not grow at 5°C, with populations declining slowly over 14 days of refrigerated storage. Strains of the organism grew well under abusive storage, increasing by 2.5 to 3.1 log CFU/g and 4.1 to 4.3 log CFU/g after 24 h at 22 and 35°C, respectively. All strains were resistant to tetracycline but were sensitive to tested cephalosporins and chloramphenicol. Resistance to penicillin was observed, but susceptibility to other members of the β-lactam group, including ampicillin, amoxicillin, and clavulanic acid, was recorded. E. albertii represents an emerging pathogen with a probable foodborne transmission route. Future research should focus on verifying food process measures able to inactivate the pathogen.
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Nemidkanam, Variya, and Nuntaree Chaichanawongsaroj. "Characterizing Kaempferia parviflora extracellular vesicles, a nanomedicine candidate." PLOS ONE 17, no. 1 (January 25, 2022): e0262884. http://dx.doi.org/10.1371/journal.pone.0262884.
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Plant-derived extracellular vesicles (EVs) are a promising candidate for nanomedicine delivery due to their bioactive cargos, high biocompatibility to human cells, biodegradability, low cytotoxicity, and potential for large-scale production. However, the research on EVs derived from medicinal plants is very limited. In this study, Kaempferia parviflora extracellular vesicles (KPEVs) were isolated by differential and sucrose density gradient centrifugation, and their size, morphology, and surface charge were characterized using transmission electron microscopy and dynamic light scattering. The biological properties of KPEVs, including their bioactive compound composition, gastric uptake, cytotoxicity, acid tolerance, and storage stability, were also examined. In addition, KPEVs had an average and uniform size of 200–300 nm and a negative surface charge of 14.7 ± 3.61 mV. Moreover, 5,7-dimethoxyflavone, the major bioactive compound of KP, was packaged into KPEVs. Meanwhile, KPEVs were resistant to gastric digestion and stably maintained at −20°C and −80°C for 8 weeks with no freeze-thaw cycle. The lipid hydrolysis during EVs storage at room temperature and 4°C were also demonstrated for the first time. Furthermore, the labeled KPEVs were internalized into adenocarcinoma gastric cells, and the cell viability was reduced in a dose-dependent manner, according to the results of the thiazolyl blue tetrazolium assay. Our study supports the potential application of KPEVs as a vehicle for anticancer or oral drugs.
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Dunphy, G., and D. Ely. "Decreased storage stability of creatine kinase in a cardiac reperfusion solution." Clinical Chemistry 36, no. 5 (May 1, 1990): 778–80. http://dx.doi.org/10.1093/clinchem/36.5.778.
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Abstract Creatine kinase (CK; EC 2.7.3.2) has been used as an indicator of myocardial cellular damage. In this study we used a Krebs-Henseleit (KH) solution to reperfuse isolated rat hearts after 24 h of cold preservation and collected the KH reperfusate for assay of CK to assess cellular damage. We wanted to determine the stability of CK in the KH solution at different cold-storage temperatures and albumin concentrations. CK activity (mean +/- SEM) after one week of refrigeration (5 degrees C) was 93% +/- 1% of control values, whereas CK activity in nitrogen-frozen (-200 degrees C) samples was only 1.6% +/- 1% of control values, and that in samples frozen at moderately low temperatures (-10 degrees C) was 63% +/- 1% of control values. To enhance stability, we added albumin at several concentrations (49, 25, 12, and 6 g/L) to reperfusion collections in which CK had been previously determined. Specimens were frozen (-10 degrees C), then re-analyzed for CK weekly for three weeks. CK activity was maintained (100% +/- 5%) only in samples containing 25 g/L or more albumin. These data suggest that refrigeration (5 degrees C) for one week maintains normal CK activity in KH solution; however, if prolonged storage is necessary, a stabilizer such as albumin (greater than or equal to 25 g/L) will maintain analyte stability in frozen storage (-10 degrees C) for at least three weeks.