Val Beasley - Academia.edu (original) (raw)

Papers by Val Beasley

Pharmacology & Toxicology, 1990

The pathophysiologic effects of anatoxin-a(s) from the cyanobacterium Anabaena flos-aquae NRC-525... more The pathophysiologic effects of anatoxin-a(s) from the cyanobacterium Anabaena flos-aquae NRC-525-17 were investigated in anaesthetized adult male Sprague Dawley rats given the toxin by continuous intravenous infusion until death. Rats (n=6) pretreated with atropine sulfate (50 mg/kg) intraperitoneally survived significantly longer (PxO.05) than non-atropinized rats (n=6), suggesting that the muscarinic effects of anatoxin-a(s) were important in the lethal syndrome. In contrast to rats only given toxin, rats that were pretreated with atropine had a decrease in heart rate and mean blood pressure that followed profound reductions in respiratory tidal and minute volume, suggesting that neuromuscular blockade of the muscles of respiration was the cause of death. Even when survival time of rats was increased by pretreatment with atropine, phrenic nerve amplitude increased, indicating a lack of a depressive effect of anatoxina(s) on central mediation of respiration. Rats (n=3) continuously ventilated during toxin infusion survived a dose more than 4 fold greater than a consistently lethal dose of the toxin. Thus, the cardiovascular effects of anatoxin-a(s) alone could not account for the death of rats. Electromyographic activity recorded from the diaphragms of rats (n=5) during continuous toxin administration revealed an increase in muscular electrical activity that became more random and finally decreased prior to death, suggesting a toxin-induced neuromuscular blockade in vivo which ultimately was the cause of death of the anatoxin-a(s) dosed rats.

Natural Toxins, 1995

The cyanobacterial toxin microcystin-LR (MCLR) is a potent inhibitor of protein phosphatases 1 an... more The cyanobacterial toxin microcystin-LR (MCLR) is a potent inhibitor of protein phosphatases 1 and 2A, and is selectively toxic to the liver in vivo and to isolated hepatocytes in vitro. This selectivity is believed to be due to toxin uptake via bile acid carriers. We investigated at the light and ultrastructural levels the effects of high concentrations of MCLR and long incubation times to determine in vitro whether fibroblasts and kidney cells (non-target cells) respond in the same manner as do hepatocytes (target cells) at low concentrations and short incubation times. Cultured rat skin fibroblasts (ATCC 1213) and rat kidney epithelial cells (ATCC 1571) were incubated with MCLR at 133 pM for 1-24 hr. Lesions in these cells were compared with those in cultured hepatocytes incubated with MCLR at 13.3 pM from 1 to 32 min. Lesions in hepatocytes, kidney cells, and fibroblasts were noted at 4 min, 1 hr, and 8 hr, respectively, after initial exposure to MCLR.

Cellular uptake of neutral red dye (NR) is currently used as an indirect measure of viable cells ... more Cellular uptake of neutral red dye (NR) is currently used as an indirect measure of viable cells in cultures. We used E-63 rat skeletal muscle cells to identify causes of NR assay variability and to develop modifications that substantially reduce it. Three methods of NR preparation and/or addition to cells were used. When NR medium was prepared, incubated overnight, and filtered to remove precipitates, the amount of dye precipitated varied greatly. Coefficients of variation (CVs) in NR uptake were greater than 25% between assays. Higher NR concentrations, longer incubation times, increased pH, and decreased temperature promoted NR precipitation in media. NR media prepared and filtered just prior to use or direct addition of prefiltered NR stock solution to cell cultures resulted in much smaller CVs between assays. NR was cytotoxic to E-63 rat muscle and primary quail myoblasts in a time- and concentration-dependent manner. NR exposure to E-63 cells for greater than 1.25 and 2 hr at 157 or 127 microg/ml, respectively, was associated with swelling and rupture of lysosomes. By contrast, there was no evidence of cytotoxicity when E-63 cells were exposed to NR for 1 hr at either 127 or 157 microg/ml. Primary quail myoblasts developed lysosomal swelling and ruptured more rapidly than E-63 cells when exposed to NR at either 127 or 157 microg/ml. For confluent 10-day cultures of E-63 cells exposed to NR at 127 microg/ml for 1 hr, the CVs within assay and between assays were 3.3-3.9% and 5.1%, respectively. For similarly exposed, actively replicating 3-day cultures of E-63 cells, the CVs within and between assays were 6.2-9.6% and 2.4%, respectively. NR uptake by the E-63 cells was linear with respect to viable cell number.

EcoHealth, Jan 18, 2015

Insufficient data from existing surveillance systems underlie societal tolerance of acute and slo... more Insufficient data from existing surveillance systems underlie societal tolerance of acute and slow-onset health disasters that threaten, harm, and kill vast numbers of humans, animals, and plants. Here we describe barriers to integrated "One Health" surveillance, including those related to a lack of medical services, professional divisions, incompatible vocabularies, isolated data sets, and territorial borders. We draw from publications of experts who justify broader and more integrated surveillance, education, and stewardship focused on preventing and mitigating disease emergence and re-emergence. In addition, we highlight efforts from Illinois, the United States and the broader world, pointing to examples of relevant education; ways to acquire, compile, and analyze diagnostic and syndromic data; mapping of diseases of humans and animals; and rapid communication of findings and recommendations. For the future, we propose using needed outcomes for health and sustainability...

Veterinary Clinics of North America Small Animal Practice, Mar 31, 1990

This article provides information on the detoxification of and supportive care for poisoned anima... more This article provides information on the detoxification of and supportive care for poisoned animals. Involved are measures to control life-threatening manifestations of toxicoses, to remove agents from the digestive tract, skin, or eyes, and to promote removal of systemically absorbed toxicants. The use of these methods is often of paramount importance in an effort to limit organ damage and to enable a poisoned animal to survive.

Toxins, 2015

Harmful cyanobacterial blooms have adversely impacted human and animal health for thousands of ye... more Harmful cyanobacterial blooms have adversely impacted human and animal health for thousands of years. Recently, the health impacts of harmful cyanobacteria blooms are becoming more frequently detected and reported. However, reports of human and animal illnesses or deaths associated with harmful cyanobacteria blooms tend to be investigated and reported separately. Consequently, professionals working in human or in animal health do not always communicate findings related to these events with one another. Using the One Health concept of integration and collaboration among health disciplines, we systematically review the existing literature to discover where harmful cyanobacteria-associated animal illnesses and deaths have served as sentinel events to warn of potential human health risks. We find that illnesses or deaths among livestock, dogs and fish are all potentially useful as sentinel events for the presence of harmful cyanobacteria that may impact human health. We also describe ways to enhance the value of reports of cyanobacteria-associated illnesses and deaths in animals to protect human health. Efficient monitoring of environmental and animal health in a One Health collaborative framework can provide vital warnings of cyanobacteria-associated human health risks.

Veterinary Clinics of North America: Small Animal Practice, 1990

The Veterinary clinics of North America. Small animal practice, 1990

ABSTRACT Objectives: The objectives of this study were to assess whether the Envirovet programme ... more ABSTRACT Objectives: The objectives of this study were to assess whether the Envirovet programme served to increase the number of practising ecosystem health professionals, as well as to measure the lasting professional and personal impact of the programme on participants.

Regulatory Toxicology and Pharmacology, 1989

An understanding of the "health" of an ecosystem after exposure to toxic chemic... more An understanding of the "health" of an ecosystem after exposure to toxic chemicals can be achieved through studies which concentrate on the description of effects on ecosystem homeostasis, identification of disruption, and determination of pathways between these. Studies using native mammals to determine effects of toxicants on terrestrial ecosystems must be designed so that they identify the populations at risk, select appropriate biological effect endpoints, and obtain appropriate numbers and types of samples and contextual ecological data. Accompanying laboratory studies are often needed to complement or confirm observations from the field. Although aquatic biologists routinely use about 10 selected native species for toxicological work, terrestrial biologists seem to prefer using laboratory mammals in "ecotoxicological" studies. Some have advocated using only laboratory rodents in a field setting, while others have suggested using both laboratory mammals and native species. We take the position that there are considerable limitations in the use of laboratory rodents in toxicological studies which purport to be meaningful with regard to prediction of toxicant-induced effects on ecological systems. Nevertheless, we are able to suggest an integrated plan that includes the systematic monitoring of native species in conjunction with laboratory animals exposed in the laboratory and in the field.

Journal of the American Veterinary Medical Association, 2001

We suggest each of us take on the daily challenge of writing and speaking to the public on scient... more We suggest each of us take on the daily challenge of writing and speaking to the public on scientific matters, always being certain to include at least one statement about how our clinical practice, our research, and our daily work as veterinarians influences, and is ...

EcoHealth, 2004

Since 1991, Envirovet Summer Institutes have provided an intensive educational program in wildlif... more Since 1991, Envirovet Summer Institutes have provided an intensive educational program in wildlife and ecosystem health to approximately 225 animal health professionals. Envirovet provides knowledge, skills, and multiple mentors to catalyze ecosystem health-oriented careers for young veterinarians. It is a total immersion experience, with the students engaged in 60-70 hours a week of instruction, 6-7 days a week, for 6 weeks. The course is comprised of lecture, laboratory, and field experiences organized into three sessions: 1) terrestrial wildlife and ecosystem health; 2) aquatic wildlife and ecosystem health; and 3) an ecosystem health approach to international development. Sessions 1 and 2 take place in Florida and Georgia; Session 3 takes place in a developing country (e.g., Kenya, Brazil, South Africa). Ultimately, the goal of Envirovet is to increase the numbers and effectiveness of veterinarians in productive ecosystem health research and application teams around the world.

Toxicol Sci, 1985

T-2 toxin given as a single intravascular dose to swine produced a shock syndrome. Dosages of 0.6... more T-2 toxin given as a single intravascular dose to swine produced a shock syndrome. Dosages of 0.6 or 4.8 mg/kg were administered to different groups of swine. Shock was characterized by reductions in cardiac output and blood pressure, and increased plasma concentrations of epinephrine, norepinephrine, thromboxane B2, 6-keto PGF1 alpha, and lactate. Total peripheral resistance was unchanged in the high-dose group but decreased in the low-dose group. Pulmonary vascular resistance increased in both groups. Decreases occurred in arterial pH and arterial oxygen partial pressure. No alterations occurred in plasma concentrations of histamine or serotonin.