Inhalation Toxicity of Brevetoxin 3 in Rats Exposed for Twenty-Two Days

Brevetoxins are potent neurotoxins produced by the marine dinoflagellate Karenia brevis. Exposure to brevetoxins may occur during a K. brevis red tide when the compounds become aerosolized by wind and surf. This study assessed possible adverse health effects associated with inhalation exposure to brevetoxin 3, one of the major brevetoxins produced by K. brevis and present in aerosols collected along beaches affected by red tide. Male F344 rats were exposed to brevetoxin 3 at 0, 37, and 237 μg/m(3) by nose-only inhalation 2 hr/day, 5 days/week for up to 22 exposure days. Estimated deposited brevetoxin 3 doses were 0.9 and 5.8 μg/kg/day for the low-and high-dose groups, respectively. Body weights of the high-dose group were significantly below control values. There were no clinical signs of toxicity. Terminal body weights of both low- and high-dose-group rats were significantly below control values. Minimal alveolar macrophage hyperplasia was observed in three of six and six of six of the low- and high-dose groups, respectively. No histopathologic lesions were observed in the nose, brain, liver, or bone marrow of any group. Reticulocyte numbers in whole blood were significantly increased in the high-dose group, and mean corpuscular volume showed a significant decreasing trend with increasing exposure concentration. Humoral-mediated immunity was suppressed in brevetoxin-exposed rats as indicated by significant reduction in splenic plaque-forming cells in both low- and high-dose-group rats compared with controls. Results indicate that the immune system is the primary target for toxicity in rats after repeated inhalation exposure to relatively high concentrations of brevetoxins

Exposure and Effect Assessment of Aerosolized Red Tide Toxins (Brevetoxins) and Asthma

addresses: National Science Foundation National Institute of Environmental Health Sciences Oceans and Human Health Center, University of Miami Rosenstiel School of Marine and Atmospheric Sciences, Miami, Florida 33136, USA. [email protected]: PMCID: PMC2717136types: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.'Reproduced with permission from Environmental Health Perspectives'Copyright © 2009 National Institute of Environmental Health SciencesIn previous studies we demonstrated statistically significant changes in reported symptoms for lifeguards, general beach goers, and persons with asthma, as well as statistically significant changes in pulmonary function tests (PFTs) in asthmatics, after exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols

Initial Evaluation of the Effects of Aerosolized Florida Red Tide Toxins (Brevetoxins) in Persons with Asthma

Florida red tides annually occur in the Gulf of Mexico, resulting from blooms of the marine dinoflagellate Karenia brevis. K. brevis produces highly potent natural polyether toxins, known as brevetoxins, that activate voltage-sensitive sodium channels. In experimental animals, brevetoxins cause significant bronchoconstriction. A study of persons who visited the beach recreationally found a significant increase in self-reported respiratory symptoms after exposure to aerosolized Florida red tides. Anecdotal reports indicate that persons with underlying respiratory diseases may be particularly susceptible to adverse health effects from these aerosolized toxins. Fifty-nine persons with physician-diagnosed asthma were evaluated for 1 hr before and after going to the beach on days with and without Florida red tide. Study participants were evaluated with a brief symptom questionnaire, nose and throat swabs, and spirometry approved by the National Institute for Occupational Safety and Health. Environmental monitoring, water and air sampling (i.e., K. brevis, brevetoxins, and particulate size distribution), and personal monitoring (for toxins) were performed. Brevetoxin concentrations were measured by liquid chromatography mass spectrometry, high-performance liquid chromatography, and a newly developed brevetoxin enzyme-linked immunosorbent assay. Participants were significantly more likely to report respiratory symptoms after Florida red tide exposure. Participants demonstrated small but statistically significant decreases in forced expiratory volume in 1 sec, forced expiratory flow between 25 and 75%, and peak expiratory flow after exposure, particularly those regularly using asthma medications. Similar evaluation during nonexposure periods did not significantly differ. This is the first study to show objectively measurable adverse health effects from exposure to aerosolized Florida red tide toxins in persons with asthma. Future studies will examine the possible chronic effects of these toxins among persons with asthma and other chronic respiratory impairment

Placental Structure and Comments on Gestational Ultrasonographic Examination

The placental structure of cetaceans is epitheliochorial and implantation is diffuse (Zhemkova 1967). Mossman (1987) described the fetal membranes of cetaceans as similar to those of Tragulidae (mouse deers) and Camelidae (camels), primarily within the later stages of development and noted that Stump et al. (1960) also illustrated early embryos as similar to artiodactyls. Mossman (1987) further noted that there is an early but temporary yolk sac or choriovitelline placenta in cetaceans that is replaced later by the chorioallantoic placenta. The epitheliochorial placenta is considered a secondary specialization and is found in the superorder Laurasiatheria, which was the last mammalian superorder to arise. This superorder includes many types of placentation, but most species with epitheliochorial placentation are found here, including cetaceans, camels, ruminants, pigs, peccaries, hippopotamuses, horses, and pangolins (Carter and Enders 2004)

Cellular and respiratory effects of aerosolized red tide toxins (brevetoxins)

Harmful algal blooms (HABs) are focal, dense aggregations of large numbers of planktonic organisms ( blooms ) that often are associated with production of biotoxins and cause harm to marine organisms and ecosystems. Florida red tide (causative dinoflagellate Karenia brevis) is one of the most notorious of all HABs, occurring on a virtually annual basis along Florida\u27s Gulf coast. Brevetoxins (biotoxins produced by K. brevis) are potent neurotoxins. Florida red tide causes major epizootics, produces toxic shellfish when the dinoflagellate is filter-accumulated in clams and oysters, and releases an irritating toxicant into the air when surf conditions are turbulent.The aim of this thesis is two-fold: first, to characterize an animal model of human brevetoxin aerosol exposure using a sheep model of compromised airways; and second, to begin addressing and identifying the cellular and immunologic consequences of brevetoxicosis using an in-vitro system. Sub-acute, 4-day exposure to pure brevetoxin-3 results in a marked, neutrophilic pulmonary inflammatory response and airway hyper-responsiveness in both allergic and non-allergic sheep. In addition, in-vivo and in-vitro experiments suggest that there are variable, but demonstrable, immunomodulatory effects of brevetoxin exposure on peripheral neutrophil and alveolar macrophage viability, function, and mediator activity. These data were novel in that this is the first animal model to show pulmonary physiologic, inflammatory, and cellular effects of exposure to environmentally relevant concentrations of aerosolized PbTx-3. The in-vitro studies provide basic and preliminary information on brevetoxicosis on the cellular level from which investigations of potential mechanisms of action may be pursued

Laboratory procedures

The main foundation to veterinary medicine is the availability of laboratory tests. These tests may be performed in-clinic or at diagnostic laboratories. In-clinic testing is advantageous in producing quick results, but demands sound technical ability, basic equipment,and access to some routine and special reagents. Laboratory-based testing can back up those routine techniques that mayor may not be available at the clinic level as well as provide specialized testing. The knowledge of commercially available diagnostic services is important as well as preparation and proper shipping of samples for accurate determinations