Publications by authors named "P H Crandall"

210 Publications

Detection and Potential Virulence of Viable but Non-Culturable (VBNC) : A Review.

Microorganisms 2021 Jan 19;9(1). Epub 2021 Jan 19.

Conrad N. Hilton College of Hotel and Restaurant Management, University of Houston, 122 Heiman Street, San Antonio, TX 78205, USA.

The detection, enumeration, and virulence potential of viable but non-culturable (VBNC) pathogens continues to be a topic of discussion. While there is a lack of definitive evidence that VBNC (Lm) pose a public health risk, recent studies suggest that Lm in its VBNC state remains virulent. VBNC bacteria cannot be enumerated by traditional plating methods, so the results from routine Lm testing may not demonstrate a sample's true hazard to public health. We suggest that supplementing routine Lm testing methods with methods designed to enumerate VBNC cells may more accurately represent the true level of risk. This review summarizes five methods for enumerating VNBC Lm: Live/Dead BacLight staining, ethidium monoazide and propidium monoazide-stained real-time polymerase chain reaction (EMA- and PMA-PCR), direct viable count (DVC), 5-cyano-2,3-ditolyl tetrazolium chloride-4',6-diamidino-2-phenylindole (CTC-DAPI) double staining, and carboxy-fluorescein diacetate (CDFA) staining. Of these five supplementary methods, the Live/Dead BacLight staining and CFDA-DVC staining currently appear to be the most accurate for VBNC Lm enumeration. In addition, the impact of the VBNC state on the virulence of Lm is reviewed. Widespread use of these supplemental methods would provide supporting data to identify the conditions under which Lm can revert from its VBNC state into an actively multiplying state and help identify the environmental triggers that can cause Lm to become virulent. Highlights: Rationale for testing for all viable Listeria (Lm) is presented. Routine environmental sampling and plating methods may miss viable Lm cells. An overview and comparison of available VBNC testing methods is given. There is a need for resuscitation techniques to recover Lm from VBNC. A review of testing results for post VBNC virulence is compared.
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http://dx.doi.org/10.3390/microorganisms9010194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7832328PMC
January 2021

Untangling the formation and liberation of water in the lunar regolith.

Proc Natl Acad Sci U S A 2019 06 20;116(23):11165-11170. Epub 2019 May 20.

Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822;

The source of water (HO) and hydroxyl radicals (OH), identified on the lunar surface, represents a fundamental, unsolved puzzle. The interaction of solar-wind protons with silicates and oxides has been proposed as a key mechanism, but laboratory experiments yield conflicting results that suggest that proton implantation alone is insufficient to generate and liberate water. Here, we demonstrate in laboratory simulation experiments combined with imaging studies that water can be efficiently generated and released through rapid energetic heating like micrometeorite impacts into anhydrous silicates implanted with solar-wind protons. These synergistic effects of solar-wind protons and micrometeorites liberate water at mineral temperatures from 10 to 300 K via vesicles, thus providing evidence of a key mechanism to synthesize water in silicates and advancing our understanding on the origin of water as detected on the Moon and other airless bodies in our solar system such as Mercury and asteroids.
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http://dx.doi.org/10.1073/pnas.1819600116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6561281PMC
June 2019

Wearable Technology Effects on Training Outcomes of Restaurant Food Handlers.

J Food Prot 2018 08;81(8):1220-1226

2 University of Arkansas Global Campus, 2 East Center Street, Fayetteville, Arkansas 72701, USA.

Food safety training does not always result in behavior change, perhaps because of flaws inherent in traditional training designs. New technologies such as augmented reality headsets or head-mounted action cameras could transform the way food safety training is conducted in the food industry. Training conducted with wearable technology presents visual content in the first-person or actor's perspective, as opposed to the traditional third-person or observer perspective. This visual hands-on first-person perspective may provide an effective way of conveying information and encouraging behavior execution because it uses the mirror neuron system. There is little published literature about the impact of perspective on food safety training outcomes, such as motivation. The present study included a repeated-measures design to determine how first- and third-person camera angles affected hand washing training reactions among 108 currently employed restaurant food handlers. Participants were assessed on their posttraining compliance intentions, compliance self-efficacy, perceived utility of the training, overall satisfaction with the training, and video perspective preference. A significant proportion of food handlers (64%) preferred the first-person video perspective ( z = 5.00, P < 0.001), and a significant correlation was found between compliance intentions and compliance self-efficacy ( r(108) = 0.361, P < 0.001) for the first-person video. No significant differences in video preference were found for demographic variables, including age (χ (2, n = 104) = 1.69, P = 0.430), which suggests that the first-person training format appeals to a diverse workforce. These findings support the application of wearable technology to enhance hand washing training outcomes across a wide range of demographic groups. This research lays the framework for future studies to assess the impact of instructional design on compliance concerning hand washing and other food handling behaviors.
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http://dx.doi.org/10.4315/0362-028X.JFP-18-033DOI Listing
August 2018

Accessing the Nitromethane (CHNO) Potential Energy Surface in Methanol (CHOH)-Nitrogen Monoxide (NO) Ices Exposed to Ionizing Radiation: An FTIR and PI-ReTOF-MS Investigation.

J Phys Chem A 2018 Mar 23;122(9):2329-2343. Epub 2018 Feb 23.

Department of Chemistry , University of Hawai'i at Ma̅noa , Honolulu , Hawaii 96822 , United States.

(D-)Methanol-nitrogen monoxide (CHOH/CDOH-NO) ices were exposed to ionizing radiation to facilitate the eventual determination of the CHNO potential energy surface (PES) in the condensed phase. Reaction intermediates and products were monitored via infrared spectroscopy (FTIR) and photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) during the irradiation and temperature controlled desorption (TPD) phase, respectively. Distinct photoionization energies were utilized to discriminate the isomer(s) formed in these processes. The primary methanol radiolysis products were the methoxy (CHO) and hydroxymethyl (CHOH) radicals along with atomic hydrogen. The former was found to react barrierlessly with nitrogen monoxide resulting in the formation of cis- and trans-methyl nitrite (CHONO), which is the most abundant product that can be observed in the irradiated samples. On the other hand, the self-recombination of hydroxymethyl radicals yielding ethylene glycol (HO(CH)OH) and glycerol (HOCHCH(OH)CHOH) is preferred over the recombination with nitrogen monoxide to nitrosomethanol (HOCHNO).
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http://dx.doi.org/10.1021/acs.jpca.7b12235DOI Listing
March 2018

Further Evidence of How Unbuffered Starvation at 4°C Influences Listeria monocytogenes EGD-e, HCC23, F2365, and Scott A.

J Food Prot 2017 10;80(10):1749-1759

1 Department of Food Science and Center for Food Safety and.

The soilborne pathogen Listeria monocytogenes frequently contaminates food products and food processing environments and is able to survive desiccation, high osmotic pressures, and starvation. However, little is known about how this pathogen survives starvation at 4°C. This study provides evidence that L. monocytogenes is able to survive total nutrient starvation for 4 weeks. L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 were starved individually in sterile water. Colony counts declined over 4 weeks, with Scott A declining the most rapidly. Transmission electron microscopy images revealed degradation of starving cell membranes and altered cytosols. Starving cells were subjected to the metabolic inhibitors fluoride, arsenite, 2,4-dinitrophenol, iodoacetate, and cyanide individually. Iodoacetate, which inhibits glyceraldehyde-3-phosphate dehydrogenase, completely reduced cultivable counts below the level of detection compared with the control starving cells; 2,4-dinitrophenol, which dissipates proton motive force, almost completely reduced cultivable counts. These results suggest that L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 are actively using part of the glycolysis pathway while starving. These results suggest that starving L. monocytogenes cells retain aspects of active metabolism.
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http://dx.doi.org/10.4315/0362-028X.JFP-17-041DOI Listing
October 2017
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