Archives
One limitation of our study was that
One limitation of our study was that all control dogs had histologic evidence of mild GI inflammation according to established WSAVA guidelines (Washabau et al., 2010), despite being apparently healthy purpose-bred research dogs housed in a controlled environment with no history of vomiting, diarrhea or other signs of GI disease, and despite having normal physical examinations and negative fecal flotations. These findings are similar to previous reports of mild histopathology changes in asymptomatic healthy, control dogs (Junginger et al., 2012, Haas et al., 2014). Histology of the canine GI tract is affected by many factors, including age, intestinal parasites, diet, intestinal flora, medications, and environmental Fer-1 (Washabau et al., 2010], Haas et al., 2014). All dogs received monthly topical parasiticide and deworming every 3 months; therefore intestinal parasitism is an unlikely explanation for the mild GI inflammation noted. The authors agree with the observation by Junginger et al., that mild histopathological abnormalities may simply represent background variation in the GI tract of normal dogs (Junginger et al., 2012). We, therefore, believe that, with the possible exception of the dog with mild gastritis, the histologic findings in the dogs in our study are consistent with a healthy GI tract, and that the histamine receptor distribution reported in our study reflects the distribution in clinically normal dogs.
Conclusion
Acknowledgements
The authors would like to thank the Mississippi State University College of Veterinary Medicine (MSU-CVM) histopathology laboratory and immunology laboratory for technical assistance, training, and advice throughout the project. The authors especially would like to thank Stephany Mays for all of her assistance and kindness. This work was supported by the MSU-CVM House Officer Grant.
Introduction
Histamine is a biogenic amine that can be produced in fish by bacterial enzymatic decarboxylation of histidine. Histamine fish allergy is one of the most prevalent illnesses associated with seafood consumption in the U.S. constituting 38% of all seafood related food-borne illnesses reported to the US Center for Disease Control (CDC, 2006). The illness is frequently associated with eating fish containing high levels of histamine with a variety of symptoms generally begin with tingling or burning sensations in the mouth followed by the development of rash, nausea, diarrhea, flushing, sweating and headache within a few minutes to 2 h after eating the fish (Bulushi, Poole, Deeth, & Dykes, 2009; Feng, Teuber, & Gershwin, 2016). Fresh fish usually contain negligible amounts of histamine. However, tuna and other pelagic species, which account for significant global fish production, contain large amounts of free histidine in muscles and are more likely to produce histamine as a result of bacterial enzymatic activity if the fish is not properly stored before consumption (Tarliane, Priscila, Warlley, & Maria Beatriz, 2011). Histamine is colorless and odorless. A high histamine level can exist in fish without noticeable changes in appearance or smell of the fish. Therefore, the rapid and reliable detection of histamine in fish has attracted significant research interest for the sake of public health and safety concerns, as well as for the global fish business. The European Union (EU) and the U.S. Food and Drug Administration (FDA) established a guidance level that the average concentration of histamine in fish for consumption must be lower than 100 ppm and 50 ppm respectively (EC, 2005, pp. 1–25; FDA, 2011, pp. 113–152).
Conventional methods for histamine detection in tuna include high performance liquid chromatography (HPLC) (Önal, Tekkeli, & Önal, 2013), enzyme-linked immunosorbent assay (ELISA) (Lupo & Mozola. 2011), liquid chromatography-mass spectrometry (LC-MS) (Ohtsubo, Kurooka, Tada, & Manabe, 2014) and fluorimetric detection (Muscarella, Lo Magro, Campaniello, Armentano, & Stacchini, 2013) with very low detection limits. However, these methods often require very expensive instrumentation with time-consuming laborious sample preparation procedures, which are performed by skilled personnel. In addition, these methods can only be used in laboratories. Therefore, there is a need to develop a sensitive, quantitative means for rapid detection of histamine in real tuna samples for on-site inspection to minimize the occurrence of histamine poisoning and enhance seafood safety.