scholarly journals Variables Affecting the Recovery of Acanthamoeba Trophozoites

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 221
Author(s):  
Monica J. Crary ◽  
Rhonda Walters ◽  
Paul Shannon ◽  
Manal M. Gabriel
Keyword(s):  
Cell Proliferation ◽  
Impact Test ◽  
Storage Conditions ◽  
Test Methods ◽  
Antimicrobial Efficacy ◽  
Recovery Method ◽  
Nutrient Density ◽  
Growth Requirements ◽  
Proliferation Assays ◽  
Recovery Methods

While the results of Acanthamoeba testing have been extensively published, laboratories conducting such testing are left to develop their own methods in the absence of a standardized methodology. The wide disparity of methods has resulted in equally inconsistent reported results for contact lens care (CLC) products. This study’s objective was to determine the source of these discrepancies by evaluating basic Acanthamoeba biology and their impact on antimicrobial efficacy testing, including the ability of a recovery method to stimulate a single trophozoite to proliferate. Antimicrobial efficacy testing was conducted using well-published Acanthamoeba strains, storage conditions, and growth-based recovery methods. To identify variables that influence results, test solutions with low Acanthamoeba disinfection rates were utilized to prevent differences from being masked by high log reductions. In addition, single-cell proliferation assays were executed to understand the growth requirements to stimulate trophozoite propagation in two recovery methods. These studies indicated that both nutrient density (>106 CFU) and the length of plate incubation (at least 14 days) could significantly influence the accurate recovery of trophozoites. Together, this study emphasizes the need to understand how Acanthamoeba trophozoites biology can impact test methods to create divergent results.

Fasteners at Low Temperatures: Characterization and Methods for Design

2011 ◽  
Author(s):  
Melanie Stephan ◽  
Jens O. Weber ◽  
Ulrich Wuttke ◽  
Christina Berger
Keyword(s):  
Impact Test ◽  
Freezing Point ◽  
Lattice Structure ◽  
Detailed Examination ◽  
Test Methods ◽  
Climatic Conditions ◽  
Test Method ◽  
Design Concepts ◽  
Ductile Behavior ◽  
Pendulum Impact

Bolted joints are a major part of wind energy plants. Due to climatic conditions, they are often exposed to temperatures far below the freezing point. Together with the multiaxial state of stress, which results from the notch effect of the thread, and possible dynamic overloads during operation, sufficient ductility of the material is needed. The state of the art method to investigate the ductile behavior of fasteners is the Charpy pendulum impact test with a V-notched specimen. According to international standard DIN EN ISO 898-1 [1] respectively ASTM F568M-07 [2], fasteners made of carbon steel and alloy steel with a body centered cubic lattice structure can be used for temperatures down to 223 K (−50°C, −58°F) as long as a minimum impact energy of 27 J at 253 K (−20°C, −4°F) is met. As there are several disadvantages in using this test method for fasteners, a detailed examination of existing test methods and design concepts is necessary to find alternatives to the Charpy pendulum impact test. Extensive quasi-static and dynamic material tests were conducted on fasteners with property classes 5.6, 10.9 and 12.9 in a temperature range between 203 K (−70°C, −94°F) and room temperature 293 K (20°C, 68°F). Both mechanical properties and the influence of different specimen geometries were evaluated. Analytical concepts for the description of the low temperature applicability of different steels were analyzed.

scholarly journals Improved Coefficient Recovery and Its Application for Rewritable Data Embedding

2021 ◽  
Vol 7 (11) ◽  
pp. 244
Author(s):  
Alan Sii ◽  
Simying Ong ◽  
KokSheik Wong
Keyword(s):  
Image Coding ◽  
Rate Distortion ◽  
Divide And Conquer ◽  
Storage Device ◽  
Data Embedding ◽  
Discrete Cosine Transformation ◽  
Recovery Method ◽  
Embedding Method ◽  
Coefficient Recovery ◽  
Recovery Methods

JPEG is the most commonly utilized image coding standard for storage and transmission purposes. It achieves a good rate–distortion trade-off, and it has been adopted by many, if not all, handheld devices. However, often information loss occurs due to transmission error or damage to the storage device. To address this problem, various coefficient recovery methods have been proposed in the past, including a divide-and-conquer approach to speed up the recovery process. However, the segmentation technique considered in the existing method operates with the assumption of a bi-modal distribution for the pixel values, but most images do not satisfy this condition. Therefore, in this work, an adaptive method was employed to perform more accurate segmentation, so that the real potential of the previous coefficient recovery methods can be unleashed. In addition, an improved rewritable adaptive data embedding method is also proposed that exploits the recoverability of coefficients. Discrete cosine transformation (DCT) patches and blocks for data hiding are judiciously selected based on the predetermined precision to control the embedding capacity and image distortion. Our results suggest that the adaptive coefficient recovery method is able to improve on the conventional method up to 27% in terms of CPU time, and it also achieved better image quality with most considered images. Furthermore, the proposed rewritable data embedding method is able to embed 20,146 bits into an image of dimensions 512×512.

scholarly journals Antibacterial Effects of Grape Extracts on Helicobacter pylori

2008 ◽  
Vol 75 (3) ◽  
pp. 848-852 ◽  
Author(s):  
Joseph C. Brown ◽  
Guohui Huang ◽  
Vivian Haley-Zitlin ◽  
Xiuping Jiang
Keyword(s):  
Cell Proliferation ◽  
Helicobacter Pylori ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Antibacterial Effects ◽  
Grape Skin ◽  
Agar Dilution ◽  
H Pylori ◽  
Proliferation Assays

ABSTRACT Anti-Helicobacter pylori activities were determined by agar dilution, confocal laser scanning microscopy, and cell proliferation assays following treatment with various grape extracts. Muscadine grape skin possessed the strongest activity, followed by grape synergy (skin and seed) and seed, suggesting that higher phenolic levels do not necessarily determine overall anti-H. pylori efficacy.

scholarly journals Inhibition of Adrenocortical Carcinoma Cell Proliferation by Steroidogenic Factor-1 Inverse Agonists

2009 ◽  
Vol 30 (3) ◽  
pp. 290-290
Author(s):  
Mabrouka Doghman ◽  
Julie Cazareth ◽  
Dominique Douguet ◽  
Franck Madoux ◽  
Peter Hodder ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Steroid Hormone ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Adrenocortical Cell ◽  
Steroidogenic Factor 1 ◽  
Inverse Agonists ◽  
Real Time Quantitative Pcr ◽  
Flow Cytometric ◽  
Proliferation Assays

ABSTRACT Context: Transcription factor steroidogenic factor-1 (SF-1) plays a pivotal role in the control of adrenocortical cell steroidogenesis and proliferation. SF-1 amplification and overexpression are found in most cases of childhood adrenocortical tumors (ACTs). Objective: Our objective was to investigate the effect of SF-1 inverse agonists of the alkyloxyphenol and isoquinolinone classes on the proliferation of human adrenocortical cell lines expressing SF-1 (H295R), in conditions of basal and increased SF-1 expression, or negative for SF-1 expression (SW-13). Main Outcome Measures: Proliferation assays, immunoblots, flow cytometric analyses, steroid hormone assays, and real-time quantitative PCR were used. Results: SF-1 inhibitors of the alkyloxyphenol class displayed a dose-dependent inhibitory effect on both SF-1-positive and -negative ACT cells, whereas SF-1 inverse agonists of the isoquinolinone class selectively inhibited cell proliferation elicited by SF-1 overexpression. These drugs also inhibited stimulated steroid hormone secretion and CYP21 and CYP17 mRNA expression. Conclusion: SF-1 inhibitors may represent a useful tool in the chemotherapy of ACTs.

Methods to Evaluate Cleaners and Sanitizers

1982 ◽  
Vol 45 (13) ◽  
pp. 1257-1260 ◽  
Author(s):  
DALE L. SCHEUSNER
Keyword(s):  
Test Methods ◽  
Test Method ◽  
Test Results ◽  
Standard Laboratory ◽  
Test Procedures ◽  
Laboratory Methods ◽  
Product Use ◽  
Cellulose Sponge ◽  
Equivalent Test ◽  
Recovery Methods

Methods to evaluate germicides can be grouped into three categories: standard laboratory tests, in-use tests and simulated-use tests. Standard laboratory methods, such as the Available Chlorine Germicidal Equivalent test, are specifically defined for reproducibility in any laboratory by any operator, but the test results often lack relevance to actual product-use conditions. In-use test methods are relevant to product-use; however, in-use test procedures do not permit proper controls to be included in the organism recovery methods. Contact plates give an estimate of organism numbers which is only 25% of the theoretical number of organisms present. Organism recovery using a swab, cellulose sponge or tube sampler give estimates of organisms ranging from 91 to 111% of theoretical. The tube sampler is a 1-in. length of flexible tubing having a 1-in. interior diameter and a smooth end, which can make a water-tight seal on a flat surface. Simulated use testing yields data which are relevant to actual product-use. A cafeteria tray is soiled, inoculated and cleaned in a manner to simulate actual product-use. This test method permits the necessary controls to be used. Tray-test reproducibility is as good as that of the other recovery methods tested and organism recovery is quantitative. The tray test provides a means for determining biological cleaning where the effect of both cleaning and germicidal activity are measured together.

Comparison of 3M™ Petrifilm™ Aerobic Count Plates to Standard Plating Methodology for Use with AOAC Antimicrobial Efficacy Methods 955.14, 955.15, 964.02, and 966.04 as an Alternative Enumeration Procedure: Collaborative Study

2013 ◽  
Vol 96 (4) ◽  
pp. 717-722 ◽  
Author(s):  
Maria T Nelson ◽  
Robert A LaBudde ◽  
Stephen F Tomasino ◽  
Rebecca M Pines ◽  
M Bennett ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Test Methods ◽  
Antimicrobial Efficacy ◽  
Plate Count ◽  
Matched Pair ◽  
Acceptance Criterion ◽  
Standard Plate Count ◽  
Test Organisms ◽  
Standard Plate ◽  
Viable Bacteria

Abstract A multilaboratory study was conducted to determine the equivalence of the 3M™ Petrifilm™ Aerobic Count Plate and standard plating methodology for measuring viable bacteria and spores recovered from hard-surface carriers (stainless steel and porcelain), also known as "control carrier counts," used in AOAC antimicrobial efficacy test methods. Six laboratories participated in the study in which carriers inoculated with Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica, and spores of Bacillus subtilis were evaluated using 3M Petrifilm Aerobic Count (AC) plates and standard plating side-by-side. The data were analyzed using a matched-pair t-test to determine the between-method effect with confidence intervals. For all test organisms pooled across all laboratories, the mean difference in log10 concentration between the standard plate count method and 3M Petrifilm AC Plates was −0.012, with a 95% confidence interval of (−0.090, +0.066), which was well within the −0.5, +0.5 interval established as the acceptance criterion. The between-carrier SD averaged 0.139; the between-replicate SD was 0.050. The carrier reproducibility, given that a single replicate per carrier is done, was estimated to be 0.148. Although differences were seen in the final concentrations of the test organisms among laboratories, there were no statistical differences between the enumeration methods. Based on the results from this study, 3M Petrifilm AC Plates are equivalent to standard plating methodology and can be used as an alternative procedure for the enumeration of test organisms used in AOAC Methods 955.14, 955.15, 964.02, and 966.04.

Reduction of Anti-FVIII Inhibitor Titers in Hemophilic Mice Infused with Syngeneic Apoptotic Cells Expressing a Human FVIII Transgene.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 216-216
Author(s):  
Rui-Jun Su ◽  
Laura Stewart ◽  
Steven W. Pipe ◽  
Neil C. Josephson
Keyword(s):  
Cell Proliferation ◽  
T Cell ◽  
Antibody Titer ◽  
Immune Tolerance ◽  
Hemophilia A ◽  
Apoptotic Cell ◽  
High Titer ◽  
T Cell Proliferation ◽  
Apoptotic Cells ◽  
Proliferation Assays

Abstract Approximately 30% of patients with severe hemophilia A develop neutralizing antibodies (inhibitors) to factor VIII (FVIII). Frequently, the inhibitors that develop are persistent and of sufficiently high titer that infusion of FVIII concentrates are ineffective for the control of bleeding episodes. At present the only method for elimination of high titer inhibitors is Immune Tolerance Induction (ITI) by exposing patients to repeated FVIII doses. However, it is extremely expensive and takes many months to complete. There is a need to develop quicker, cheaper, and more reliable protocols for inducing tolerance in patients with high titer FVIII inhibitors, and of preventing their occurrence in patients at high risk. In a non-inflammatory environment, autologous apoptotic cells are processed by immature, non-activated dendritic cells (DCs) capable of initiating peripheral immune tolerance through the stimulation of different classes of regulatory T cells. Furthermore, it has been demonstrated that antigen specific tolerance can be induced by delivery of a foreign protein within dying syngeneic cells (Liu et al, J Exp Med196: 1091, 2002). We hypothesize that immune tolerance to FVIII can be induced by the infusion of apoptotic autologous cells engineered to carry a FVIII expression vector. We generated a fibroblast cell line from a tail snip of a 129Sv-FVIIIKO mouse and transduced the cells with a foamy virus vector expressing a B-domain deleted human FVIII construct. Expression of human FVIII was detected by ELISA in the supernatant of cultured transduced fibroblasts. These transduced cells were induced to apoptosis by serum starvation for 24–30 hr prior to infusion into 129Sv-FVIIIKO mice. Treated mice received two weekly doses of 1x107 serum starved transduced fibroblasts. Control mice were infused with culture media alone. Ten days after the final infusion, experimental and control mice were challenged with 4 weekly intravenous doses of 0.2 μg albumin free recombinant human FVIII (ADVATE). Ten days after the final dose of ADVATE blood samples were collected and evaluated for inhibitor titer by Bethesda assay and for total anti-FVIII antibody titer by ELISA. Three weeks later, T cell proliferation assays were performed on samples from mice in each group. The mice that received apoptotic cells had lower inhibitor titers than controls, 156.7 ± 82.7 BU/ml (n = 6) versus 331.3 ± 183.9 BU/ml (n = 11) (p = 0.017, Welch’s t-test). However, total antibody titer levels determined by ELISA were not significantly different between the two groups. T-cell proliferation assays also showed a reduced T cell response in the apoptotic cell treated mice with a stimulation index that was half that seen in the controls. Our data show that inhibitor titers and T cell responses in hemophilia A mice challenged by albumin free recombinant FVIIII can be reduced by the prior infusion of apoptotic syngeneic cells transduced with a human FVIII expressing vector. Future work will focus on optimizing apoptotic cell delivery protocols to maximally suppress the immune response to FVIII and on elucidating the mechanisms responsible for our findings. Figure Figure

Sign in / Sign up

Export Citation Format

Share Document