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Extraction and Chemistry of Rubber Allergens
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
Several of the sulfur rubber accelerator spot and screening tests take advantage of zinc dialkyldithiocarbamates (ZDTC) metal reactivity. Two spot tests protocols for accelerator identification are detailed in The Vanderbilt Latex Handbook,32 although a rubber extraction procedure was not described. One spot test uses a cobalt oleate reagent. The cobalt (Co) oleate reagent is made by heating cobalt carbonate in oleic acid to approximately 280°C with dilution in toluene after cooling. Milligram quantities of the accelerator are dissolved in a drop or two of toluene, and a drop of the cobalt oleate reagent is added. Dialkyldithiocarbamates (DTCs) produce a dark yellow-green color, MBT a pale green color, and thioureas a lavender to purple color. The disulfides, thiurams, and MBTS must first be reduced using zinc and dilute hydrochloric acid before the addition of the cobalt oleate reagent to produce a yellow-green or pale green color, respectively. Another method described in The Vanderbilt Latex Handbook uses an aqueous copper solution and concentrated aqueous ammonia to detect DTCs by the formation of a dark brown precipitate.
Anti-microbial and Anti-oxidant Properties of Solvent Extract of Lichen Species Collected from Kodaikanal Hills, Western Ghats of Tamil Nadu
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
R. Kalidoss, M. Mariraj, M. Shenbagam, J. Merlin Seles, K. Arun Prasath, N. Rajaprabu, P. Ponmurugan
The spot test was carried out by scraping the cortex using a sharp blade to expose the medulla. The color reaction was observed by applying the reagent in the medulla. The chemical reagents used are potassium hydroxide (K), aqueous solution of calcium hypochlorite or bleaching powder (C), and para phenylene diamine (Culberson 1969). The color appears on the thallus as red or yellow. By introducing a drop of test solution on the cortex or medulla using a capillary tube or glass rod, the reaction was indicated by changes in color. The reactions positive to the tests were marked as “+” and negative as “−”. The KC test was carried out by applying K solution first, followed by C solution on the cortex or medulla to witness the color changes. The iodine test was also applied on the cortex to note the presence or absence of the polysaccharides.
Orally Induced Tolerance to Nickel: The Role of Oral Exposure (Orthodontic Devices) in Preventing Sensitization
Published in Jurij J. Hostýnek, Howard I. Maibach, Nickel and the Skin, 2019
Jurij J. Hostýnek, Katherine E. Reagan, Howard I. Maibach
Cavelier et al. (1985) investigated nickel release from clothing objects and the tolerance of NAH patients for such objects and for nickel-plated metal discs. They concluded that good tolerance can only be observed if use of nickel is avoided altogether. They also disqualify the DMG spot test as indicator of tolerable nickel release because of its limited sensitivity (DMG pos. = 10 ppm), potentially yielding false negative results (van Ketel and Liem, 1981; Wall, 1992).
Freeze-dried fecal samples are biologically active after long-lasting storage and suited to fecal microbiota transplantation in a preclinical murine model of Clostridioides difficile infection
Published in Gut Microbes, 2020
Julie Reygner, Christine Charrueau, Johanne Delannoy, Camille Mayeur, Véronique Robert, Céline Cuinat, Thierry Meylheuc, Aurélie Mauras, Jérémy Augustin, Ioannis Nicolis, Morgane Modoux, Francisca Joly, Anne-Judith Waligora-Dupriet, Muriel Thomas, Nathalie Kapel
The agar spot test adapted from Tejero-Sarinena et al.50 was used for the detection of activity against CD R20291 (027 type strain). Lactic acid (500 mM), Lactobacillus sp., and Bifidobacterium infantis subsp. longum CUETM 89–215 were used as positive chemical and biological controls, whereas Escherichia. coli CIP 54.8, Klebsiella pneumonia CIP104771, and Staphylococcus aureus ATCC 25923 were used as negative controls. An overnight culture of each bacterial suspension (20 μl) was used as control and an equal volume of each fecal suspension of thawed G10 and G80 and rehydrated FD samples were deposited on cellulose disks and placed on WCB agar for overnight incubation at 37°C in an anaerobic atmosphere. Agar plates were then covered with Brucella agar containing a CD R20291 culture (OD = 1). The chemical control, lactic acid, was added to an open well (50 µl). Plates were incubated for another overnight period under anaerobic conditions at 37°C and the zones of inhibition of the CD culture around each spot were measured. Results (from three independent experiments) are expressed as the ratio between inhibition diameters of pure bacteria or stool samples and chemical control.
A bacteriophage cocktail targeting Escherichia coli reduces E. coli in simulated gut conditions, while preserving a non-targeted representative commensal normal microbiota
Published in Gut Microbes, 2018
Tomasz Cieplak, Nitzan Soffer, Alexander Sulakvelidze, Dennis Sandris Nielsen
For this pilot study, we specifically formulated a bacteriophage preparation to target one strain from the representative ileal consortium: E. coli DSM 1058. For the phage cocktail, individual monophages were selected from Intralytix's bacteriophage collection, based on their ability to lyse the DSM 1058 strain in the classical Spot Test assay.22 Various dilutions were used for the spot test to differentiate between lysis and inhibition (i.e., low dilutions resulting in plaques were tested as well). The resulting susceptibility data were analyzed using the PhageSelector™ program (proprietary program developed by Intralytix) to formulate bacteriophage cocktail Ec17B153DK1. The resulting cocktail is composed of 3 phages (ECML-363, ECML-122 and ECML-359) each having potent lytic activity against E. coli DSM 1058. Each component monophage was propagated separately in their respective E. coli host strains at 37°C, with Multiplicity of infections (MOIs) ranging from 2 × 10−4 to 1 × 10−1. Following propagation, each phage was harvested by filtering through a 0.2-micron filter and concentrated/buffer exchanged in a 0.85% saline solution. Following buffer exchange, the three monophages were combined in approximately equal concentrations to produce the phage cocktail Ec17B153DK1. The final cocktail was then sterile filtered through a 0.2-micron filter and stored refrigerated (2–8°C) until use.
Facts and ideas from anywhere
Published in Baylor University Medical Center Proceedings, 2018
Although marijuana impairs driving, there is no reliable on-the-spot test for marijuana intoxication!5 Urine tests, used widely by employers, are not useful for testing impairment. They detect breakdown products for tetrahydrocannabinol, or THC, marijuana's psychoactive component. Such metabolites can be found months after a marijuana high has worn off. Thus, barring confession, there is no way to tell if a driver is high on marijuana. The only test that currently shows any promise for detecting marijuana intoxication is blood plasma analysis, but empowering police officers to draw blood on the roadside would set up a dangerous precedent for “individual liberties.” And, the connection between blood THC levels and intoxication is not well defined. A breath analyzer test for marijuana is being investigated. Another possibility is to develop a test that determines when THC was consumed. We have a way to go here.