Influence of Methylene Blue or Dimethyl Sulfoxide on Larval Zebrafish Development and Behavior

The use of larval zebrafish developmental testing and assessment, specifically larval zebrafish locomotor activity, has been recognized as a higher throughput testing strategy to identify developmentally toxic and neurotoxic chemicals. There are, however, no standardized protocols for this type of assay, which could result in confounding variables being overlooked. Two chemicals commonly employed during early-life stage zebrafish assays, methylene blue (antifungal agent) and dimethyl sulfoxide (DMSO, a commonly used vehicle) have been reported to affect the morphology and behavior of freshwater fish. In this study, we conducted developmental toxicity (morphology) and neurotoxicity (behavior) assessments of commonly employed concentrations for both chemicals (0.6-10.0 μM methylene blue; 0.3%-1.0% v/v DMSO). A light-dark transition behavioral testing paradigm was applied to morphologically normal, 6 days postfertilization (dpf) zebrafish larvae kept at 26°C. Additionally, an acute DMSO challenge was administered based on early-life stage zebrafish assays typically used in this research area. Results from developmental toxicity screens were similar between both chemicals with no morphological abnormalities detected at any of the concentrations tested. However, neurodevelopmental results were mixed between the two chemicals of interest. Methylene blue resulted in no behavioral changes up to the highest concentration tested, 10.0 μM. By contrast, DMSO altered larval behavior following developmental exposure at concentrations as low as 0.5% (v/v) and exhibited differential concentration-response patterns in the light and dark photoperiods. These results indicate that developmental DMSO exposure can affect larval zebrafish locomotor activity at routinely used concentrations in developmental neurotoxicity assessments, whereas methylene blue does not appear to be developmentally or neurodevelopmentally toxic to larval zebrafish at routinely used concentrations. These results also highlight the importance of understanding the influence of experimental conditions on larval zebrafish locomotor activity that may ultimately confound the interpretation of results.

Inconsistencies in variable reporting and methods in larval zebrafish behavioral assays

New approaches in developmental neurotoxicity (DNT) screening are needed due to the tens of thousands of chemicals requiring hazard assessments. Zebrafish (Danio rerio) are an alternative vertebrate model for DNT testing, but without a standardized protocol for larval behavioral assays, comparison of results among laboratories is challenging. To evaluate the congruence of protocols across laboratories, we conducted a literature review of DNT studies focusing on larval zebrafish behavior assays and cataloged experimental design consistencies. Our review focused on 51 unique method variables in publications where chemical exposure occurred in early development and subsequent larval locomotor evaluation focused on assays that included a light/dark photoperiod transition. We initially identified 94 publications, but only 31 exclusively met our inclusion criteria which focused on parameters that are important to an assay employed by our laboratory. No publication reported 100% of the targeted variables; only 51 to 86% of those variables were reported in the reviewed publications, with some aspects of the experimental design consistent among laboratories. However, no protocol was exactly the same for any two publications. Many of these variables had more than one parameter/design reported, highlighting the inconsistencies among methods. Overall, there is not only a strong need for the development of a standardized testing protocol for larval zebrafish locomotor assays, but there is also a need for a standardized protocol for reporting experimental variables in the literature. Here we include an extensive guideline checklist for conducting larval zebrafish developmental behavior assays.

Developmental Neurotoxicity and Behavioral Screening in Larval Zebrafish with a Comparison to Other Published Results

With the abundance of chemicals in the environment that could potentially cause neurodevelopmental deficits, there is a need for rapid testing and chemical screening assays. This study evaluated the developmental toxicity and behavioral effects of 61 chemicals in zebrafish (Danio rerio) larvae using a behavioral Light/Dark assay. Larvae (n = 16–24 per concentration) were exposed to each chemical (0.0001–120 μM) during development and locomotor activity was assessed. Approximately half of the chemicals (n = 30) did not show any gross developmental toxicity (i.e., mortality, dysmorphology or non-hatching) at the highest concentration tested. Twelve of the 31 chemicals that did elicit developmental toxicity were toxic at the highest concentration only, and thirteen chemicals were developmentally toxic at concentrations of 10 µM or lower. Eleven chemicals caused behavioral effects; four chemicals (6-aminonicotinamide, cyclophosphamide, paraquat, phenobarbital) altered behavior in the absence of developmental toxicity. In addition to screening a library of chemicals for developmental neurotoxicity, we also compared our findings with previously published results for those chemicals. Our comparison revealed a general lack of standardized reporting of experimental details, and it also helped identify some chemicals that appear to be consistent positives and negatives across multiple laboratories.

Zebrafish irritant responses to wildland fire-related biomass smoke are influenced by fuel type, combustion phase, and byproduct chemistry

Human exposure to wildfire-derived particulate matter (PM) is linked to adverse health outcomes; however, little is known regarding the influence of biomass fuel type and burn conditions on toxicity. The aim of this study was to assess the irritant potential of extractable organic material (EOM) of biomass smoke condensates from five fuels (eucalyptus, pine, pine needle, peat, or red oak), representing various fire-prone regions of the USA, burned at two temperatures each [flaming (approximately 640°C) or (smoldering approximately 500°C)] using a locomotor assay in zebrafish (Danio rerio) larvae. It was postulated that locomotor responses, as measures of irritant effects, might be dependent upon fuel type and burn conditions and that these differences relate to combustion byproduct chemistry. To test this, locomotor activity was tracked for 60 min in 6-day-old zebrafish larvae (25-32/group) immediately after exposure to 0.4% dimethyl sulfoxide (DMSO) vehicle or EOM from the biomass smoke condensates (0.3-30 µg EOM/ml; half-log intervals). All EOM samples produced concentration-dependent irritant responses. Linear regression analysis to derive rank-order potency indicated that on a µg PM basis, flaming pine and eucalyptus were the most irritating. In contrast, on an emission-factor basis, which normalizes responses to the amount of PM produced/kg of fuel burned, smoldering smoke condensates induced greater irritant responses (>100-fold) than flaming smoke condensates, with smoldering pine being the most potent. Importantly, irritant responses significantly correlated with polycyclic aromatic hydrocarbon (PAH) content, but not with organic carbon or methoxyphenols. Data indicate that fuel type and burn condition influence the quantity and chemical composition of PM as well as toxicity.

Zebrafish Locomotor Responses Reveal Irritant Effects of Fine Particulate Matter Extracts and a Role for TRPA1

Exposure to fine particulate matter (PM) air pollution causes adverse cardiopulmonary outcomes. Yet, the limited capacity to readily identify contributing PM sources and associated PM constituents in any given ambient air shed impedes risk assessment efforts. The health effects of PM have been attributed in part to its capacity to elicit irritant responses. A variety of chemicals trigger irritant behavior responses in zebrafish that can be easily measured. The purposes of this study were to examine the utility of zebrafish locomotor responses in the toxicity assessment of fine PM and its chemical fractions and uncover mechanisms of action. Locomotor responses were recorded in 6-day-old zebrafish exposed for 60 min in the dark at 26 °C to the extractable organic matter of a compressor-generated diesel exhaust PM (C-DEP) and 4 of its fractions (F1-F4) containing varying chemical classes of increasing polarity. The role of the transient receptor potential (TRP) cation channel TRPA1, a chemical sensor in mammals and zebrafish, in locomotor responses to C-DEP, was also examined. Acrolein, an environmental irritant and known activator of TRPA1, and all extracts induced concentration-dependent locomotor responses whose potencies ranked as follows: polar F3 > weakly polar F2 > C-DEP > highly polar F4 > nonpolar F1, indicating that polar and weakly polar fractions that included nitro- and oxy-polyaromatic hydrocarbons (PAHs), drove C-DEP responses. Irritant potencies in fish positively correlated with mutagenic potencies of the same extracts in strains of Salmonella sensitive to nitro- and oxy-PAHs, further implicating these chemical classes in the zebrafish responses to C-DEP. Pharmacologic inhibition of TRPA1 blocked locomotor responses to acrolein and the extracts. Taken together, these data indicate that the zebrafish locomotor assay may help expedite toxicity screening of fine PM sources, identify causal chemical classes, and uncover plausible biological mechanisms.

Acute and developmental behavioral effects of flame retardants and related chemicals in zebrafish

As polybrominated diphenyl ethers are phased out, numerous compounds are emerging as potential replacement flame retardants for use in consumer and electronic products. Little is known, however, about the neurobehavioral toxicity of these replacements. This study evaluated the neurobehavioral effects of acute or developmental exposure to t-butylphenyl diphenyl phosphate (BPDP), 2-ethylhexyl diphenyl phosphate (EHDP), isodecyl diphenyl phosphate (IDDP), isopropylated phenyl phosphate (IPP), tricresyl phosphate (TMPP; also abbreviated TCP), triphenyl phosphate (TPHP; also abbreviated TPP), tetrabromobisphenol A (TBBPA), tris (2-chloroethyl) phosphate (TCEP), tris (1,3-dichloroisopropyl) phosphate (TDCIPP; also abbreviated TDCPP), tri-o-cresyl phosphate (TOCP), and 2,2-,4,4'-tetrabromodiphenyl ether (BDE-47) in zebrafish (Danio rerio) larvae. Larvae (n≈24 per dose per compound) were exposed to test compounds (0.4-120 μM) at sub-teratogenic concentrations either developmentally or acutely, and locomotor activity was assessed at 6 days post fertilization. When given developmentally, all chemicals except BPDP, IDDP and TBBPA produced behavioral effects. When given acutely, all chemicals produced behavioral effects, with TPHP, TBBPA, EHDP, IPP, and BPDP eliciting the most effects at the most concentrations. The results indicate that these replacement flame retardants may have developmental or pharmacological effects on the vertebrate nervous system.

Developmental exposure to organophosphate flame retardants elicits overt toxicity and alters behavior in early life stage zebrafish (Danio rerio)

Organophosphate flame retardants (OPFRs) are common replacements for the phased-out polybrominated diphenyl ethers (PBDEs) and have been detected at high concentrations in environmental samples. OPFRs are structurally similar to organophosphate pesticides and may adversely affect the developing nervous system. This study evaluated the overt toxicity, uptake, and neurobehavioral effects of tris (1,3-dichloro-2-propyl) phosphate (TDCPP), tris (2-chloroethyl) phosphate (TCEP), tris (1-chloro-2-propyl) phosphate (TCPP), and tris (2,3-dibromopropyl) phosphate (TDBPP) in early life stage zebrafish. Chlorpyrifos was used as a positive control. For overt toxicity and neurobehavioral assessments, zebrafish were exposed from 0 to 5 days postfertilization (dpf). Hatching, death, or malformations were evaluated daily. Teratogenic effects were scored by visual examination on 6 dpf. To evaluate uptake and metabolism, zebrafish were exposed to 1 µM of each organophosphate (OP) flame retardant and collected on 1 and 5 dpf to monitor accumulation. Larval swimming activity was measured in 6 dpf larvae to evaluate neurobehavioral effects of exposures below the acute toxicity threshold. TDBPP elicited the greatest toxicity at >1 µM. TDCPP and chlorpyrifos were overtly toxic at concentrations ≥10 µM, TCEP, and TCPP were not overtly toxic at the doses tested. Tissue concentrations increased with increasing hydrophobicity of the parent chemical after 24 h exposures. TDCPP and TDBPP and their respective metabolites were detected in embryos on 5 dpf. For all chemicals tested, developmental exposures that were not overtly toxic significantly altered larval swimming activity. These data indicate that OPFRs adversely affect development of early life stage zebrafish.

Acute administration of dopaminergic drugs has differential effects on locomotion in larval zebrafish

Altered dopaminergic signaling causes behavioral changes in mammals. In general, dopaminergic receptor agonists increase locomotor activity, while antagonists decrease locomotor activity. In order to determine if zebrafish (a model organism becoming popular in pharmacology and toxicology) respond similarly, the acute effects of drugs known to target dopaminergic receptors in mammals were assessed in zebrafish larvae. Larvae were maintained in 96-well microtiter plates (1 larva/well). Non-lethal concentrations (0.2-50 μM) of dopaminergic agonists (apomorphine, SKF-38393, and quinpirole) and antagonists (butaclamol, SCH-23390, and haloperidol) were administered at 6 days post-fertilization (dpf). An initial experiment identified the time of peak effect of each drug (20-260 min post-dosing, depending on the drug). Locomotor activity was then assessed for 70 min in alternating light and dark at the time of peak effect for each drug to delineate dose-dependent effects. All drugs altered larval locomotion in a dose-dependent manner. Both the D1- and D2-like selective agonists (SKF-38393 and quinpirole, respectively) increased activity, while the selective antagonists (SCH-23390 and haloperidol, respectively) decreased activity. Both selective antagonists also blunted the response of the larvae to changes in lighting conditions at higher doses. The nonselective drugs had biphasic effects on locomotor activity: apomorphine increased activity at the low dose and at high doses, while butaclamol increased activity at low to intermediate doses, and decreased activity at high doses. This study demonstrates that (1) larval zebrafish locomotion can be altered by dopamine receptor agonists and antagonists, (2) receptor agonists and antagonists generally have opposite effects, and (3) drugs that target dopaminergic receptors in mammals appear, in general, to elicit similar locomotor responses in zebrafish larvae.

Zebrafish developmental screening of the ToxCast™ Phase I chemical library

Zebrafish (Danio rerio) is an emerging toxicity screening model for both human health and ecology. As part of the Computational Toxicology Research Program of the U.S. EPA, the toxicity of the 309 ToxCast™ Phase I chemicals was assessed using a zebrafish screen for developmental toxicity. All exposures were by immersion from 6-8 h post fertilization (hpf) to 5 days post fertilization (dpf); nominal concentration range of 1 nM-80 μM. On 6 dpf larvae were assessed for death and overt structural defects. Results revealed that the majority (62%) of chemicals were toxic to the developing zebrafish; both toxicity incidence and potency was correlated with chemical class and hydrophobicity (logP); and inter-and intra-plate replicates showed good agreement. The zebrafish embryo screen, by providing an integrated model of the developing vertebrate, compliments the ToxCast assay portfolio and has the potential to provide information relative to overt and organismal toxicity.

Assessing locomotor activity in larval zebrafish: Influence of extrinsic and intrinsic variables

The U.S. Environmental Protection Agency is evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. We are exploring methods to detect developmentally neurotoxic chemicals using zebrafish behavior at 6 days of age. The behavioral paradigm simultaneously tests individual larval zebrafish under both light and dark conditions in a 96-well plate using a video tracking system. We have found that many variables affect the level or pattern of locomotor activity, including age of the larvae, size of the well, and the presence of malformations. Some other variables, however, do not appear to affect larval behavior including type of rearing solution (10% Hank's vs. 1:3 Danieau vs 60 mg/kg Instant Ocean vs 1× and 1:10× EPA Moderately Hard Water). Zebrafish larval behavior using a microtiter plate format may be an ideal endpoint for screening developmentally neurotoxic chemicals, but it is imperative that many test variables be carefully specified and controlled.

Rearing conditions differentially affect the locomotor behavior of larval zebrafish, but not their response to valproate-induced developmental neurotoxicity

Zebrafish (Danio rerio) are widely used in developmental research, but still not much is known about the role of the environment in their development. Zebrafish are a highly social organism; thus exposure to, or isolation from, social environments may have profound developmental effects. Details of rearing conditions are often sparse in the zebrafish literature. This study compared (1) the activity of larval zebrafish that were raised individually vs in groups, and (2) the effect of the developmental neurotoxicant valproate. We randomly assigned embryos to single- or group-reared social environments from 0 to 5days post fertilization (dpf), while treating them with or without valproate (final concentration 48μM) from 0 to 2dpf, resulting in a total of four groups (group control, group treated, single control, single treated). At 5dpf all embryos were transferred to singly-housed environments where they remained for locomotor activity testing (alternating periods of light and dark) conducted on day 6. Larvae that had been reared in groups had higher levels of activity in the dark period compared to larvae that had been raised individually. Valproate increased activity in both the singly-reared and group-reared larvae during periods of darkness but not light. Further analyses of dark activity indicated that rearing condition did not differentially affect larval responses to valproate. These results indicate that rearing conditions affected the locomotion of zebrafish larvae, but did not alter the effect of the developmental neurotoxicant valproate.

Acute neuroactive drug exposures alter locomotor activity in larval zebrafish

As part of the development of a rapid in vivo screen for prioritization of toxic chemicals, we have begun to characterize the locomotor activity of zebrafish (Danio rerio) larvae by assessing the acute effects of prototypic drugs that act on the central nervous system. Initially, we chose ethanol, d-amphetamine, and cocaine, which are known, in mammals, to increase locomotion at low doses and decrease locomotion at higher doses. Wild-type larvae were individually maintained in 96-well microtiter plates at 26 degrees C, under a 14:10 h light:dark cycle, with lights on at 0830 h. At 6 days post-fertilization, ethanol (1-4% v/v), d-amphetamine sulfate (0.1-20.0 microM) or cocaine hydrochloride (0.2-50.0 microM) were administered to the larvae by immersion. Beginning 20 min into the exposure, locomotion was assessed for each animal for 70 min using 10-minute, alternating light (visible light) and dark (infrared light) periods. Low concentrations of ethanol and d-amphetamine increased activity, while higher concentrations of all three drugs decreased activity. Because ethanol effects occurred predominately during the light periods, whereas the d-amphetamine and cocaine effects occurred during the dark periods, alternating lighting conditions proved to be advantageous. These results indicate that zebrafish larvae are sensitive to neuroactive drugs, and their locomotor response is similar to that of mammals.

Repeated spike exposure to the insecticide chlorpyrifos interferes with the recovery of visual sensitivity in rats

Reports from Japan and India and data submissions to the US EPA indicate that exposure to cholinesterase (ChE)-inhibiting organophosphorous insecticides (OP) can produce ocular toxicity, in particular long-lasting changes in retinal physiology and anatomy. We have examined the effects of a 1 year dietary exposure to the OP chlorpyrifos (CPF) on retinal structure and function. Adult male Long-Evans rats were fed CPF in their diet at the rate of 0, 1 (low), or 5 (high) mg/kg body weight/day. In addition, half of each feeding group received an oral (spike) dose of CPF in corn oil (45 mg/kg) or corn oil (VEH) alone every 2 months, resulting in six exposure groups: Control-VEH, Control-CPF, Low-VEH, Low-CPF, High-VEH, and High-CPF. Dark-adapted electroretinograms (ERG) were measured 3-5 months (n= 15-18/group) after the completion of dosing. There were no significant differences between dose or spike groups in a-wave, b-wave, or oscillatory potential amplitudes or implicit times. In addition, the time course of dark adaptation were measured in a subset of these rats (6-8/group) eight months after the completion of dosing by determining the flash intensity needed to elicit a 40 microV b-wave at selected intervals after bleaching 90% of the photopigment. Rats receiving the episodic oral spike of CPF showed a slowed recovery of dark-adapted sensitivity compared to rats receiving the corn oil VEH across chronic dosing conditions. No effects were seen on retinal morphology. This result suggests that episodic high dose exposures to CPF may result in altered retinal function. This effect, akin to effects seen in aging humans and humans exposed to other ChE-inhibiting compounds, may reflect alterations in the photoreceptors and retinal pigment epithelium (RPE) complex necessary for regenerating photopigment.

Neurochemical effects of chronic dietary and repeated high-level acute exposure to chlorpyrifos in rats

Very little is known about the effects of chronic exposure to relatively low levels of anticholinesterase insecticides or how the effects of chronic exposure compare to those of higher, intermittent exposure. To that end, adult male rats were fed an anticholinesterase insecticide, chlorpyrifos (CPF), for 1 year at three levels of dietary exposure: 0, 1, or 5 mg/kg/day (0+oil, 1+oil, and 5+oil). In addition, half of each of these groups also received a bolus dosage of CPF in corn oil ("spiked" animals; 60 mg/kg initially and 45 mg/kg thereafter) every 2 months (0+CPF, 1+CPF, 5+CPF). Animals were analyzed after 6 or 12 months of dosing, and again 3 months after cessation of dosing (i.e., "recovery" animals-six experimental groups with n = 4-6/group/time point). Cholinesterase (ChE) activity was measured in retina, whole blood, plasma, red blood cells, diaphragm, and brain [pons, striatum, and the rest of the brain (referred to simply as "brain")]. Muscarinic receptor density was assessed in retina, pons, and brain, whereas dopamine transporter density and the levels of dopamine and its metabolites were assessed in striatum. Cholinesterase activity at 6 and 12 months was not different in any of the tissues, indicating that a steady state had been reached prior to 6 months. The 1+oil group animals showed ChE inhibition only in the blood, whereas the 5+oil group exhibited > or = 50% ChE inhibition in all tissues tested. One day after the bolus dose, all three groups (0+CPF, 1+CPF, 5+CPF) showed > or = 70% ChE inhibition in all tissues. Muscarinic receptor density decreased only in the brain of the 5+oil and 5+CPF groups, whereas dopamine transporter density increased only at 6 months in all three spiked groups. Striatal dopamine or dopamine metabolite levels did not change at any time. Three months after CPF dosing ended, all end points had returned to control levels. These data indicate that, although chronic feeding with or without intermittent spiked dosages with CPF produces substantial biochemical changes in a dose- and tissue-related manner, there are no persistent biochemical changes.

Effects of chronic dietary and repeated acute exposure to chlorpyrifos on learning and sustained attention in rats

Cognitive and motor impairment often follow acute poisoning with an organophosphorous (OP) pesticide. However, the persistence of these effects and the conditions necessary for their appearance are not clear: two specific concerns are whether symptomatic poisoning is necessary for persistent effects, and whether inhibition of cholinesterase (ChE) activity is a protective metric of OP exposure. This study examined the effects of chronic dietary and repeated high-level acute exposure to the pesticide chlorpyrifos (diethyl 3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) on learning and attention. Beginning at 3 months of age, male Long-Evans rats received dietary CPF at a daily dose of 0, 1, or 5 mg/kg for 1 year. Half of each dietary group also received an acute oral dose of CPF (initial dose at 60 mg/kg, 5 doses at 45 mg/kg) every 2 months. Beginning 2 weeks before the fourth acute dose, behavioral assessments were conducted on the eight rats in each of the six exposure groups (0-Oil, 0-CPF, 1-Oil, 1-CPF, 5-Oil, and 5-CPF). Using an auto-shaping procedure, the groups learned to press a lever for food in the following order: 5-Oil, 5-CPF, 1-Oil, and 0-Oil. The 0-CPF and 1-CPF groups did not learn the response in three 50-trial sessions. Chronic CPF did not affect acquisition of other behaviors required by a signal detection task (SDT) designed to assess sustained attention. The sixth acute CPF dose significantly disrupted the SDT in all dosed groups. Two months after the end of dosing, performance of the SDT was impaired in the 5-CPF group. These data suggest that learning the contingency between an action and reward may be accelerated by chronic exposure to CPF and inhibited by previous symptomatic exposure to CPF, and that persistent cognitive impairment may follow if CPF exposure inhibits brain ChE activity and is accompanied by acute doses sufficient to induce signs of toxicity.

Automated measurement of acetylcholinesterase activity in rat peripheral tissues

The accepted mechanism of toxicity of many organophosphorous and carbamate insecticides is inhibition of acetylcholinesterase activity. In mammals, part of the toxicity assessment usually includes monitoring blood and/or brain acetylcholinesterase inhibition. Other tissues, however, contain cholinesterase activity (i.e. acetyl- and butyryl-cholinesterase), and the inhibition of that activity may be informative for a full appraisal of the toxicity profile. The present group of studies first optimized the variables for extraction and solubilization of cholinesterase activity from various rat tissues and then refined an existing automated method, in order to differentially assess acetyl and butyrylcholinesterase activity in those tissues. All these studies were conducted using tissues from untreated, Long-Evans, adult rats. The first studies determined the effect of Triton X-100 or salt (NaCl) on the extraction and solubilization of cholinesterase activity from retina, brain, striated muscle, diaphragm, and heart: phosphate buffer plus detergent (1% Triton X-100) yielded the highest activity for most tissues. For striated muscle, however, slightly more activity was extracted if the phosphate buffer contained both 1% Triton X-100 and 0.5 M NaCl. It was also noted that the degree of homogenization of some tissues (e.g. striated muscle) must be increased for maximal solubilization of all cholinesterase activity. Subsequent studies developed a method for assessing the level of acetylcholinesterase, butyrylcholinesterase and total cholinesterase activity in these tissues using an automated analyzer. In conclusion, automated assay of acetylcholinesterase activity in cholinergically innervated tissues in the rat (other than brain) is achievable and relatively convenient.

Wellness perception in persons with traumatic brain injury and its relation to functional independence

OBJECTIVES

To test the reliability and validity of a perceptual wellness measure in persons after traumatic brain injury (TBI) and to determine whether a relation exists between functional independence and wellness perceptions in the same population.

DESIGN

Survey research.

SETTING

A private, residential brain injury program.

PARTICIPANTS

A convenience sample of 49 patients (43 men, 6 women) with TBI whose mean age was 32.1 years (range, 18-61yr) and mean time since injury was 10.47 years (range, 1-21yr).

MAIN OUTCOME MEASURES

The Perceived Wellness Survey (PWS) assessed wellness. The PWS has 6 subscales measuring physical, psychologic, emotional, intellectual, spiritual, and social wellness. The FIM instrument was used to measure functional status.

RESULTS

The mean PWS score (15.99) for the sample was comparable to published samples of adults (mean, 15.31-16.51); however, the reliability of the composite score (alpha = .58) and the subscales (alpha = .32-.64) was less than that obtained in previous samples (composite alpha = 0.91; subscale alpha = .64-.81). The correlations between the PWS and the FIM scores were not significant.

CONCLUSIONS

The PWS in its composite form is a reliable measure for use with persons with TBI. The finding that perceived wellness and functional independence were not related suggests that these constructs are unique and thus should both be measured. The measurement of perceptions will enable the provider to consider a client holistically and to develop programs that address quality of life issues. Further, because perceptions influence behaviors, understanding a person's perceptions in multiple dimensions may provide a useful and necessary framework for developing intervention programs that address behavioral and cognitive issues that are important to that person.

Evaluation of ewe vaccination as a tool for increasing bighorn lamb survival following pasteurellosis epizootics

We conducted field and laboratory experiments to evaluate whether treating pregnant bighorn ewes with a combination of an experimental Pasteurella trehalosi and Mannheimia haemolytica (formerly P. haemolytica) vaccine and a commercially-available bovine P. multocida and M. haemolytica vaccine would increase lamb survival following a pneumonia epidemic. Three free-ranging bighorn herds affected by pasteurellosis outbreaks between November 1995 and June 1996 were included in the field experiment. Post-epidemic lamb survival was low in all three herds in 1996, with November lamb:ewe ratios of < or = 8:100. In March 1997, thirty-six ewes (12/herd) were captured and radiocollared. Half of the ewes captured in each herd were randomly selected to receive both vaccines; the other half were injected with 0.9% saline solution as controls. Lambs born to radiocollared ewes were observed two or more times per week and were considered to have survived if they were alive in October 1997, about 6 mo after birth. Lamb survival differed among herds (range 22% to 100%), and survival of lambs born to vaccinated ewes was lower (P = 0.08) than survival of lambs born to unvaccinated ewes. Bronchopneumonia (pasteurellosis) was the dominant cause of mortality among lambs examined. We concurrently evaluated vaccine effects on survival of lambs born to seven captive ewes removed from the wild during the 1995-96 epidemic. Antibody titers were high in captive ewes prior to vaccination, and vaccines failed to enhance antibody titers in treated captive ewes. None of the captive-born lambs survived. These data suggest that, using existing technology, vaccinating bighorn ewes following pneumonia epidemics has little chance of increasing neonatal survival and population recovery.

Use of a polymerase chain reaction method to detect the leukotoxin gene lktA in biogroup and biovariant isolates of Pasteurella haemolytica and P trehalosi

OBJECTIVE

To determine whether Pasteurella haemolytica and P trehalosi isolates possess the structural gene for Pasteurella leukotoxin lktA and whether beta-hemolytic activity of these isolates correlated with detection of the lktA gene.

SAMPLE POPULATION

147 P haemolytica isolates from 21 biovariant groups and 101 P trehalosi isolates from 7 biovariant groups. In addition, P multocida and organisms from 7 other genera were tested to establish specificity of the procedure.

PROCEDURE

Isolates were observed for beta-hemolysis. A polymerase chain reaction (PCR) procedure was used to amplify the RTX domain of the Pasteurella lktA gene.

RESULTS

The lktA gene was detected in 108 (44%) isolates, including 15 associated with respiratory tract disease. All but 2 (98%) of the isolates that had the lktA gene were beta-hemolytic when grown on sheep blood agar. The remaining 140 isolates were negative for the lktA gene and hemolytic activity.

CONCLUSIONS AND CLINICAL RELEVANCE

Hemolytic activity of P haemolytica and P trehalosi isolates correlated with detection of the lktA gene for all but 2 isolates. However, 56% of isolates tested were negative for the lktA gene and beta-hemolytic activity. Leukotoxin production and secretion is a major virulence factor when other conditions are favorable for disease development. Therefore, identification of strains that possess the lktA gene may aid in the evaluation of the pathogenic potential of Pasteurella strains carried by wild and domestic animals.

Gestational exposure to chlorpyrifos: comparative distribution of trichloropyridinol in the fetus and dam

Chlorpyrifos (O,O'-diethyl O-[3,5,6-trichloro-2-pyridyl] phosphorothionate) is a commonly used anticholinesterase insecticide, and therefore the potential for human exposure is high. The present time course and dose response studies were conducted to delineate the toxicokinetics of chlorpyrifos and its metabolites in the pregnant rat and fetus. Time-pregnant, Long-Evans rats were treated orally with chlorpyrifos during late gestation (Gestational Days 14-18). Following euthanasia the level of chlorpyrifos and its metabolites, chlorpyrifos-oxon and 3,5,6-trichloro-2-pyridinol (TCP), were measured in both fetal and maternal brain and liver (limits of quantitation: 59.2, 28.8, and 14.0 ng/g tissue, respectively). In addition, cholinesterase inhibition was also measured in the same tissues for comparison. TCP was the only component detected. The highest level of TCP and the lowest level of cholinesterase activity showed the same time of peak effect: 5 h after the last dose. The concentration of TCP in the maternal liver was approximately fivefold higher than the TCP concentration in fetal liver, but, paradoxically, the concentration of TCP in the fetal brain was two- to fourfold higher than the TCP concentration in the maternal brain. The half-life of the TCP was identical in all tissues examined (12-15 h). These toxicokinetic results suggest that the fetal nervous system may be exposed to a higher concentration of chlorpyrifos than the maternal nervous system when the dam is orally exposed to chlorpyrifos during late gestation.

Immunologic responses of domestic and bighorn sheep to a multivalent Pasteurella haemolytica vaccine

The efficacy of a Pasteurella haemolytica vaccine (serotypes A1, A2, and T10) to induce humoral antibodies and alter colonization of the upper respiratory tract by related P. haemolytica spp. strains was evaluated in 10 bighorn (Ovis canadensis canadensis) and 10 domestic (Ovis aries) sheep. Sheep of each species were divided into five pairs based on age and history of respiratory disease. One sheep in each pair was vaccinated twice 2 wk apart with 2 ml of vaccine (VAC group) and the remaining animals (NV group) were injected with 2 ml of sterile saline. Mild, transient lameness was the only observed adverse effect. Blood sera from the sheep were tested for agglutinating antibodies against whole cells of A1, A2, and T10 and for leukotoxin neutralizing antibodies. Antibody titers were expressed as the reciprocal log2 of the highest reactive dilutions. Domestic sheep > 1-yr-old and two bighorn sheep with a history of A1 infection had higher titers throughout the study against A1 cells than domestic sheep < 1-yr-old and bighorns without a history of A1 infection. Both domestic and bighorn sheep had log2 titers of 8 to 12 against A2 cells and 6 to 12 against T10 cells during this time. Bighorn sheep in the VAC group had 2 to 32 fold titer increases for A1 cells by 2 wk post-vaccination (PV) compared to 0 to 2 fold increases in VAC domestic sheep. Two to 16 and 0 to 8 fold increases in antibodies titers to A2 and T10 cells, respectively, were detected in sera of both VAC groups. Sera of bighorn sheep with a history of respiratory disease and all domestic sheep had log2 leukotoxin neutralizing antibody titers of 4 to 14 in contrast to < or = 2 in sera of bighorn sheep without a history of respiratory disease. Neutralizing antibody titers of two bighorns without a history of respiratory disease in the VAC group increased from log2 0 to 5 in one and from 0 to 9 in the other 2 wk PV. Antibody increases in these animals were no longer evident at 16 wk PV while titers of animals with histories of disease remained relatively stable. The types and numbers of Pasteurella spp. isolated from nasal and pharyngeal swabs varied throughout the study without conclusive evidence of suppression of colonization. Although the animals were not experimentally challenged to determine the efficacy of the vaccine, one VAC and one NV bighorn sheep died following introduction of an A2 P. haemolytica strain when leukotoxin neutralizing antibodies had returned to pre-vaccination levels. This vaccine appeared to be safe for use in bighorn sheep and stimulated moderate but transient increases in antibody levels which should provide some protection against naturally occurring disease. A vaccine which would induce production of high and maintained antibodies against multiple strains of P. haemolytica would be valuable for use in bighorn sheep maintained in captivity or when captured for relocation.

Sample preparation and high-performance liquid chromatographic analysis of deoxyribonucleoside triphosphates in individual rat embryos

A rapid, robust, and sensitive method has been developed to measure concentrations of deoxyribonucleoside triphosphates in individual, day 14 rat embryos by modifying and optimizing existing methods for cellular extracts. Significant changes include: (i) oxidative degradation of ribonucleoside triphosphates using methylamine at lower pH (decreased from 6.5 to 4.0) to improve poor HPLC peak shape of early eluting nucleotides; (ii) glass fiber disc solid-phase extraction of the reaction mixture, which dramatically reduces impurities that interfere with nucleotide measurement, eliminates the necessity of column regeneration, and allows mobile phase recycling; and (iii) lower ionic strength (reduced from 0.4 to 0.26 or 0.12 M ammonium phosphate) and higher pH (increased from 3.25 to 5.55 or 6.98, respectively) mobile phase, conditions which are less destructive to the column's bonded phase and silica support, thereby contributing to longer column life. Enhancements include: (i) filtration of the sample prior to HPLC injection and addition of an in-line filter, guard column, and saturating precolumn of silica in the mobile phase flow, which aids substantially in extending column life and improves chromatographic stability, and (ii) inclusion of an internal standard to correct for mechanical losses. Limits of determination at a signal to noise ratio of 6:1 range from 5.5 to 12 pmol on-column or 0.41 to 0.87 pmol/mg of embryonic tissue depending on the specific nucleotide. Recoveries are quantitative for all nucleotides, and interassay variabilities are between 5 and 7% when quantified by peak height. The method has also been applied successfully to analysis of murine erythroleukemic cell cultures and this, when coupled with the embryo results, suggests its general utility.

Biovariants of isolates of Pasteurella from domestic and wild ruminants

A total of 608 bacterial isolates previously identified as Pasteurella haemolytica biotypes A and 3, P. trehalosi, and P. multocida, were separated into 73 distinct biovariants using 21 phenotypic characteristics. The largest group (54%) of wildlife isolates was identified as biogroup 2 and biogroup 2 variants. Biogroup 2 and biogroup 2 variants accounted for only 17% of isolates from domestic ruminants and were all from sheep. In contrast, 43% of isolates from domestic ruminants were identified as biogroup 1 and biogroup 1 variants, whereas only 6% of isolates from wildlife were identified in these groups. The majority of biogroup 1 isolates from wild ruminants were from 1 group of bighorn sheep in Arizona that were geographically separated from other wildlife sampled. Similarly, 1 biogroup 2 variant, 2E, was cultured only from free-ranging Dall sheep in Alaska. Twelve percent of domestic isolates and 6% of wildlife isolates were indole positive. The remaining isolates from wildlife (33%) and domestic animals (30%) were distributed among 53 distinct biovariants. None of these individual biovariants represented >4% of the total isolates. Phenotypic characterization was valuable for distinguishing between isolates from different hosts and from different geographic areas and can be used to assist in epidemiologic studies.

Pasteurella spp. in sympatric bighorn and domestic sheep

Domestic sheep were sighted at different times from 1991 to 1993 on four Nevada (USA) ranges occupied by bighorn sheep. Nasal and pharyngeal swab samples were collected from both sheep species and cultured to determine if any strains of Pasteurella spp. were shared on range conditions after contact of the two species. Pasteurella spp. were isolated from all 38 bighorn sheep and 16 of 17 domestic sheep included in this study. The isolates were characterized on the bases of species, biotype, serotype, biogroup, and restriction enzyme analyses (REA) as well as ribotyping of bacterial DNA. A P. haemolytica biotype 3, biogroup 11 isolate from a domestic sheep had biochemical, REA, and ribotype profiles which were identical to those of isolates from three bighorn sheep on the same range. None of the other isolates were found to be common to the two sheep species. Disease was not detected in any of the bighorn populations. However, bighorn sheep populations were extirpated on two ranges while increasing on the other two, including the range on which P. haemolytica biotype 3, biogroup 11 strain was isolated. Declining sheep numbers were not correlated with the presence of any one strain of Pasteurella spp from the sheep.

Serologic survey for infectious pathogens in free-ranging American bison

From November 1991 through March 1992, we evaluated 101 free-ranging American bison (Bison bison) from Yellowstone National Park, Wyoming (USA) for exposure to infectious organisms that commonly infect cattle. No titers were detected for bluetongue virus, bovine leukemia virus, or Campylobacter fetus in these 101 bison. Detectable antibodies occurred against Anaplasma marginale (eight of 76, 11%), bovine respiratory syncytial virus (31 of 101, 31%), bovine viral diarrhea (31 of 101, 31%), bovine herpesvirus 1 (29 of 76, 38%), Leptospira interrogans icterohaemorrhagiae (four of 101, 4%), L interrogans hardjo (seven of 101, 7%), L interrogans autumnalis (one of 101, 1%), L interrogans bratislava (seven of 101, 7%), L interrogans australis (one of 101, 1%), and parainfluenza 3 virus (27 of 75, 36%). The low antibody titers and the lack of gross lesions are evidence that while previous exposure to infectious organisms may have occurred, none appeared to have active infections.

Stability of a perturbed Leslie model

A small perturbation introduced in the stochastic Leslie model leads to a long-lived stable population in a region or parameter space where the stochastic model predicts the demise of the population. This somewhat surprising result is understood by considering a related model with a density-dependent sex ratio which exhibits similar features.

Validation of the use of 6,6'-dithiodinicotinic acid as a chromogen in the Ellman method for cholinesterase determinations

The Ellman method for cholinesterase determination is a spectrophotometric method which entails the use of 5,5'-dithiobis-(2-nitrobenzoic) acid (DTNB) as a chromogen and records the level of cholinesterase activity as the change in absorbance at 412 nm. Although this procedure commonly poses no problem, an exception arises when analyzing tissues rich in hemoglobin, because hemoglobin also optimally absorbs light at 400-430 nm. Use of 6,6'-dithiodinicotinic acid (DTNA) might be a solution because, like DTNB, it also is a chromogen for sulfhydryl groups, but with an optimal absorption wavelength of 340 nm (ie removed from the hemoglobin absorbance maximum). Our validation studies indicate that although DTNA is a slightly less efficient indicator of sulfhydryl group concentration, DTNA yields similar activity and degree of enzyme inhibition in tissues from control and treated animals. Moreover, because the assay is read at 340 nm instead of 412 nm, the DTNA assay is markedly more sensitive for determining cholinesterase activity in hemoglobin-rich tissues. Since the advantages of the DTNA method far outweigh the disadvantages, it should be regarded as a sensitive and convenient procedure for determining cholinesterase activity, especially in hemoglobin-rich tissues.

Isolation of Pasteurella spp. from free-ranging American bison (Bison bison)

From November 1991 through March 1992, nasal and pharyngeal swab samples were collected from 45 bison (Bison bison) from Yellowstone National Park, Montana (USA) and cultured for Pasteurella spp. Thirteen isolates of Pasteurella spp. were recovered from 10 (22%) of the animals. Ten isolates were from pharyngeal samples in contrast to three isolates from nasal samples. Pasteurella haemolytica (six biotype T, two biotype A, and two biotype 3) was the predominant Pasteurella species. Five biotype T isolates were serotype 4 and the sixth agglutinated in antisera 3, 4, and 10. Both biotype A isolates were untypable with antisera to recognized type strains. Pasteurella multocida was isolated from the pharyngeal samples of one animal. Two isolates could not be identified to species.

Tuberculosis in free-ranging, semi free-ranging and captive cervids

Cervids were one of the earliest sources of food for humans. Evidence exists of some degree of human management of cervids in Norway over 50,000 years ago. Cervids are popular wild animals for viewing in National Parks and Wildlife Reserves; they have also become popular as an alternative livestock species, and are being farmed and ranched commercially. Confinement of animals and the resultant increase in population density have increased the likelihood of infectious and parasitic diseases. Cervids are susceptible to tuberculosis caused by Mycobacterium spp. (M. bovis, M. Tuberculosis, M. avium). Tuberculosis has affected the cervid industry, causing concern among wildlife managers and regulatory agencies in countries where attempts are being made to eradicate tuberculosis. The author discusses the epizootiology of tuberculosis in the various existing management situations. Husbandry practices which either favour or inhibit the potential occurrence of tuberculosis are described.

Susceptibility of elk (Cervus elaphus) to experimental infection with Anaplasma marginale and A. ovis

Anaplasma ovis was experimentally transmitted from domestic sheep to elk (Cervus elaphus) and back to splenectomized sheep. No rickettsemias were detected but serum from three of seven experimentally inoculated elk developed Anaplasma spp.-reactive antibody as measured by indirect immunofluorescence (IIF) or by the rapid card agglutination and complement fixation assays. Three elk were experimentally infected with A. marginale. The rickettsiae were detected in blood of these elk and caused disease in a splenectomized domestic bovine calf after subinoculation of blood from the elk. All three elk had positive titers with IIF. No clinical signs of illness were noted in any elk inoculated with either Anaplasma species.

TeamWorks: a model for continuous quality improvement in the health care industry

Total quality management (TQM) or continuous quality improvement (CQI) are terms no longer being used exclusively within the manufacturing industry sector. Health care facilities, such as hospitals and nursing homes, are beginning to actively compete with each other for patients as well as face new regulations from the government. Hence, it is imperative that these facilities reevaluate their services and correct any production problems in order to be cost-effective and efficient in providing quality. Therefore, the objective of this article is to describe a model developed for improvement of hospital-wide services provided by the Baptist Health Systems' Montclair facility, a private, community hospital located in Birmingham, Alabama. The TeamWorks for Quality model, used to charter over 40 teams, illustrates how managers and employees can build a multifaceted process that delivers services in excess of customer expectations.

Bacteria isolated from nasal and tonsillar samples of clinically healthy Rocky Mountain bighorn and domestic sheep

Nasal and tonsillar samples were collected from 14 free-ranging clinically healthy Rocky Mountain bighorn sheep (Ovis canadensis canadensis) and 10 domestic sheep (Ovis aries). We identified 194 bacterial isolates, including 101 from bighorn and 93 from domestic sheep. Of these isolates, 115 were gram-positive and 79 were gram-negative. Staphylococcus species were the most numerous gram-positive organisms and had a higher incidence in samples from domestic than from bighorn sheep. In contrast Streptococcus species were present in higher numbers in samples from bighorn sheep. Pasteurella haemolytica, the most common gram-negative bacterium, was isolated from five of five tonsillar but from none of ten nasal samples of domestic sheep, and from seven of eight tonsillar and three of ten nasal samples of bighorn sheep. Most bacteria isolated were considered opportunistic pathogens. However, of the bacteria isolated, P. haemolytica, P. multocida, and Actinomyces pyogenes are most frequently associated with respiratory disease.

Hematologic, serologic values, histopathologic and fecal evaluations of bison from Yellowstone Park

Hematologic and blood chemistry parameters were measured in 149 free-ranging American bison (Bison bison) from Yellowstone National Park, Wyoming (USA). Additionally, histopathologic evaluations of lung, liver, spleen, kidney, and mesenteric and bronchial lymph nodes were made from ten animals. Forty-five fecal samples were screened for the presence of helminth ova. Leukopenia and markedly low blood urea nitrogen concentrations were the most notable differences observed from other bison populations. All tissues examined were essentially normal; there was evidence of moderate intestinal parasite burdens.