Pharmacokinetics and pharmacodynamics of standard nerve agent medical countermeasures in Göttingen Minipigs

Animal research continues to serve a critical role in the testing and development of medical countermeasures. The Göttingen minipig, developed for laboratory research, may provide many benefits for addressing research questions within chemical defense. Targeted development of the Göttingen minipig model could reduce reliance upon non-human primates, and improve study design, statistical power, and throughput to advance medical countermeasures for regulatory approval and fielding. In this vein, we completed foundational pharmacokinetics and physiological safety studies of intramuscularly administered atropine sulfate, pralidoxime chloride (2-PAM), and diazepam across a broad range of doses (1-6 autoinjector equivalent) using adult male Göttingen minipigs (n=11; n=4-8/study) surgically implanted with vascular access ports and telemetric devices to monitor cardiovascular, respiratory, arterial pressure, and temperature signals. Pharmacokinetic data were orderly and the concentration maximum mirrored available human data at comparably scaled doses clearly for atropine, moderately for 2-PAM, and poorly for diazepam. Time to peak concentration approximated 2, 7, and 20 min for atropine, 2-PAM, and diazepam, respectively, and the elimination half-life of these drugs approximated 2 hr (atropine), 3 hr (2-PAM), and 8 hr (diazepam). Atropine sulfate dose-dependently increased the magnitude and duration of tachycardia and decreased the PR and ST intervals (consistent with findings obtained from other species). Mild hypothermia was observed at the highest diazepam dose. Göttingen minipigs appear to provide a ready and appropriate large animal alternative to non-human primates, and further development and evaluation of novel nerve agent medical countermeasures and treatment strategies in this model are justified.

Development and characterization of an automated behavioral assessment platform for the Göttingen minipig

The Göttingen minipig is fast becoming the standard for assessing dermal chemical hazards because, like most swine, its skin is predictive of human skin response and because this strain's smaller size makes laboratory manipulations and husbandry easier. Unfortunately, standard behavioral tests and apparatus have not been developed for behavioral assessments of this swine strain. Indeed, computer-controlled automated behavioral testing procedures are much needed. The present research advanced this goal by producing a home-cage behavioral testing system that could accommodate minipigs of various sizes (ages). An aluminum frame housed three levers for recording operant responses, and LEDs above and below each lever served as discriminative stimuli. A commercially available food pellet dispenser was attached to a specialized pellet receptacle capable of measuring pellet retrieval. Two behavioral tests were selected and adapted from our commonly used non-human primate behavioral assessments: delayed match-to-sample (a memory test) and temporal response differentiation (a time-estimation test). Minipigs were capable of learning both tests and attaining stable performance. Next, scopolamine was used to validate the sensitivity of the behavioral tests for gauging behavioral perturbations in this swine strain. Scopolamine dose-effect functions were comparable to those observed in other species, including non-human primates, wherein 37.5 µg/kg of scopolamine (administered intramuscularly) reduced responding approximately 50%. Thus, we were successful in developing the apparatus and automated operant behavioral tests necessary to characterize drug safety in this swine strain. This capability will be valuable for characterizing chemical agent toxicity as well as the safety and efficacy of medical countermeasures.

Implementation of Manual and Automated Water Regulation for Rats (Rattus norvegicus) and Ferrets (Mustela putorius)

Water regulation is a procedure that allows animals to consume water volumes equivalent to ad libitum access, but access is limited to specific time intervals (that is, water is not available outside of the designated access periods). Despite the relatively common use of water regulation in research, the implementation method is rarely detailed, stating only that water was available in the animal's home cage at specific times. For planned toxicologic assessments, we placed rats (n = 510) and ferrets (n = 16) on water regulation using both automated and manual methods. In testing our systems, we defined "successful implementation" as maintenance of appropriate weight gain and health status. An automated system that controlled water access to an entire rat rack was successful for most rats, but several rats failed to consume enough water even after 2 wk of experience. Manual methods of water regulation were successful in rats by either moving the cage to prevent access to the drinking valve or by placing/removing water bottles. An automated system that controlled water access from water bottles was implemented for ferrets and was maintained for up to 30 wk. Retrospective comparison of body weights to standard growth curves for both species showed that all animals grew normally despite water regulation. Differences in the systems and some species considerations provide insights into the key elements necessary for successful water regulation in rats and ferrets.

Conjugates of human serum butyrylcholinesterase and nerve agents are behaviorally safe in rhesus macaques

Exogenously administered human serum butyrylcholinesterase (Hu BChE) affords protection by binding to organophosphorus (OP) nerve agents and pesticides in circulation. The resulting Hu BChE-OP conjugate undergoes 'aging' and the conjugate circulates until cleared from the body. Thus, we evaluated the effects of Hu BChE-OP conjugates on the general health and operant behavior of macaques. Rhesus macaques trained to perform a six-item serial probe recognition (SPR) task were administered 30 mg/kg of Hu BChE-soman conjugate (n = 4) or Hu BChE-VX conjugate (n = 4) by intramuscular injection. Performance on the SPR task was evaluated at 60-90 min after conjugate administration and daily thereafter for the next 4 weeks. Diazepam (3.2 mg/kg), a positive control, was administered 5 weeks after conjugate administration and performance on the SPR task was evaluated as before. Blood collected throughout the study was analyzed for acetylcholinesterase (AChE) and BChE activities. Residual BChE activity of conjugates displayed a similar pharmacokinetic profile as free Hu BChE. Neither of the Hu BChE-OP conjugates produced clear or pronounced degradations in performance on the SPR task. In contrast, diazepam clearly impaired performance on the SPR task on the day of administration in 7 of 8 macaques (and sometimes longer). Taken together, these results suggest that Hu BChE-OP conjugates are safe and provide further support for the development of Hu BChE as a bioscavenger for use in humans.

Evaluation of adenosine A1 receptor agonists as neuroprotective countermeasures against Soman intoxication in rats

Soman, an organophosphorus (OP) compound, disrupts nervous system function through inactivation of acetylcholinesterase (AChE), the enzyme that breaks down acetylcholine at synapses. Left untreated, a state of prolonged seizure activity (status epilepticus, SE) is induced, causing widespread neuronal damage and associated cognitive and behavioral impairments. Previous research demonstrated that therapeutic stimulation of A1 adenosine receptors (A1ARs) can prevent or terminate soman-induced seizure. This study examined the ability of three potent A1AR agonists to provide neuroprotection and, ultimately, prevent observable cognitive and behavioral deficits following exposure to soman. Sprague Dawley rats were challenged with a seizure-inducing dose of soman (1.2 x LD50) and treated 1 min later with one of the following A1AR agonists: (6)-Cyclopentyladenosine (CPA), 2-Chloro-N6-cyclopentyladenosine (CCPA) or N-bicyclo(2.2.1)hept-2-yl-5'-chloro-5'-deoxyadenosine (cdENBA). An active avoidance shuttle box task was used to evaluate locomotor responses to aversive stimuli at 3, 7 and 14 days post-exposure. Animals treated with CPA, CCPA or cdENBA demonstrated a higher number of avoidance responses and a faster reaction to the aversive stimulus than the soman/saline control group across all three sessions. Findings suggest that A1AR agonism is a promising neuroprotective countermeasure, capable of preventing the long-term deficits in learning and memory that are characteristic of soman intoxication.

Organoleptic assessment and median lethal dose determination of oral aldicarb in rats

Aldicarb, a carbamate pesticide, is an acetylcholinesterase inhibitor, with oral median lethal dose (LD₅₀ ) estimates in rats ranging from 0.46 to 0.93 mg/kg. A three-phase approach was used to comprehensively assess aldicarb as an oral-ingestion hazard. First, the solubility of aldicarb in popular consumer beverages (bottled water, apple juice, and 2% milk) was assessed. Lethality was then assessed by administering aldicarb in bottled water via gavage. A probit model was fit to 24-h survival data and predicted a median lethal dose of 0.83 mg/kg (95% CI: 0.54-1.45 mg/kg; slope: 4.50). Finally, organoleptic properties (e.g., taste, smell, and texture) were assessed by allowing rats to voluntarily consume 3.0 mL of the above beverages as well as liquid eggs adulterated with aldicarb at various concentrations. This organoleptic assessment determined that aldicarb was readily consumed at lethal and supralethal doses. Overt toxic signs presented within 5 min post-ingestion, and all rats died within 20 min after consuming the highest concentration (0.542 mg/mL), regardless of amount consumed. Because rats have more developed chemoreceptive capabilities than humans, these results suggest that aldicarb may be consumed in toxic or even lethal concentrations by humans in a variety of beverages or foods.

Carfentanil toxicity in the African green monkey: Therapeutic efficacy of naloxone

Carfentanil is an ultra-potent opioid with an analgesic potency 10,000 times that of morphine but has received little scientific investigation. Three experiments were conducted to evaluate the toxicity of carfentanil and the efficacy of naloxone in adult male African green monkeys. The first experiment determined the ED₅₀ (found to be 0.71 μg/kg) of subcutaneous carfentanil for inducing bradypnea and/or loss of posture. Experiment 2 attempted to establish the ED₅₀ of naloxone for rapidly reversing the bradypnea/loss of posture induced by carfentanil (1.15 μg/kg). Experiment 3 evaluated the effects of carfentanil (0.575 μg/kg) alone, the safety of naloxone (71-2841 μg/kg), and the efficacy of naloxone (71-710 μg/kg) administration at two time points following carfentanil (1.15 μg/kg) on operant choice reaction time. Collectively, these experiments characterized the temporal progression of carfentanil-induced toxic signs, determined the range of naloxone doses that restored respiratory and gross behavioral function, and determined the time course and range of naloxone doses that partially or completely reversed the effects of carfentanil on operant choice reaction time performance in African green monkeys. These results have practical relevance for the selection of opioid antagonists, initial doses, and expected functional outcomes following treatment of synthetic opioid overdose in a variety of operational/emergency response contexts.

Behavioral, Pharmacokinetic, and Cardiovascular Evaluation of Candidate Oximes in African Green Monkeys

Oxime reactivators are critical antidotes after organophosphate pesticide or nerve agent poisoning, directly restoring the function of inhibited acetylcholinesterase. In the continuing search for more broad-spectrum acetylcholinesterase reactivators, this study evaluated one of the leading next-generation oxime reactivators: methoxime, (1,1′-trimethylene bis[4-(hydroxyimino)methyl]pyridinium dichloride (MMB-4). The pharmacokinetics of both salts of MMB-4 (dichloride [2Cl] and dimethanesulphonate [DMS]) were characterized across a range of relevant doses (19, 58, and 116 µmol/kg, intramuscular) in a nonhuman primate model (male African green monkeys), and only subtle differences were observed between the salts. Additionally, the behavioral and cardiovascular safety of these MMB-4 salts was compared directly to other available oximes (HI-6 2Cl, HI-6 DMS, and pyridine-2-aldoxime chloride (2-PAM Cl)) at comparable projected doses. Automated operant behavioral tests were used to examine attention, motivation, visual discrimination, concept execution, and fine motor coordination after high doses of all oxime salts, and of all oximes studied, only the highest dose of 2-PAM Cl (447 µmol/kg) disrupted behavioral performance. Likewise, the effects of a range of doses of MMB-4 2Cl or DMS, HI-6 2Cl or DMS, or 2-PAM Cl on cardiovascular parameters were measured in African green monkeys implanted with telemetry devices. Only a small transient decrease in pulse pressure was observed following administration of the highest dose of MMB-4 DMS (116 µmol/kg). Thus, MMB-4 salts, up to the 9× equivalent of a projected autoinjector dose in humans, did not produce behavioral or cardiovascular toxicity in African green monkeys in the current study, and the pharmacokinetic parameters were orderly and predictable.

Behavioral intoxication following voluntary oral ingestion of tetramethylenedisulfotetramine: Dose-dependent onset, severity, survival, and recovery

Tetramethylenedisulfotetramine (tetramine, or TETS) is a highly toxic rodenticide that has been responsible for over 14,000 accidental and intentional poisonings worldwide. Although the vast majority of TETS poisonings involved tainted food or drink, the laboratory in vivo studies of TETS intoxication used intraperitoneal injection or gavage for TETS exposure. Seeking to develop and characterize a more realistic model of TETS intoxication in the present study, rats were trained to rapidly and voluntarily consume a poisoned food morsel. Initially, the overt toxic effects of TETS consumption across a large range of doses were characterized, then a focused range of doses was selected for more intensive behavioral evaluation (in operant test chambers providing a variable-interval schedule of food reinforcement). The onset of intoxication following voluntary oral consumption of TETS was rapid, and clear dose-dependent response-rate suppression was observed across multiple performance measures within the operant-chamber environment. At most doses, recovery of operant performance did not occur within 30h. Food consumption and body weight changes were also dose dependent and corroborated the behavioral measures of intoxication. This voluntary oral-poisoning method with concomitant operant-behavioral assessment shows promise for future studies of TETS (and other toxic chemicals of interest) and may be extremely valuable in characterizing treatment outcomes.

Sex and the stimulus-movement effect: Differences in acquisition of autoshaped responding in cynomolgus monkeys

The stimulus-movement effect refers to the phenomenon in which stimulus discrimination or acquisition of a response is facilitated by moving stimuli as opposed to stationary stimuli. The effect has been found in monkeys, rats, and humans, but the experiments conducted did not provide adequate female representation to investigate potential sex differences. The current experiment analyzed acquisition of stimulus touching in a progressive series of classical conditioning procedures in cynomolgus monkeys (Macaca fascicularis) as a function of sex and stimulus movement. Classical conditioning tasks arrange two or more stimuli in relation to each other with different temporal and predictive relations. Autoshaping procedures overlay operant contingencies onto a classical-conditioning stimulus arrangement. In the present case, a neutral stimulus (a small gray square displayed on a touchscreen) functioned as the conditional stimulus and a food pellet functioned as the unconditional stimulus. Although touching is not required to produce food, with repeated stimulus pairings subjects eventually touch the stimulus. Across conditions of increasing stimulus correlation and temporal contiguity, male monkeys acquired the response faster with a moving stimulus. In contrast, females acquired the response faster with a stationary stimulus. These results demonstrate that the stimulus-movement effect may be differentially affected by sex and indicate that additional experiments with females are needed to determine how sex interacts with behavioral phenomena discovered and elaborated almost exclusively using males.

VX toxicity in the Göttingen minipig

The present experiments determined the intramuscular LD₅₀ of VX in male Göttingen minipigs at two stages of development. In pubertal animals (115 days old), the LD₅₀ of VX was indeterminate, but approximated 33.3μg/kg. However, in sexually mature animals (152 days old), the LD₅₀ was estimated to be only 17.4μg/kg. Signs of nerve agent toxicity in the Göttingen minipig were similar to those described for other species, with some notable exceptions (such as urticaria and ejaculation). Latencies to the onset of sustained convulsions were inversely related to the administered dose of VX in both ages of minipigs. Additionally, actigraphy was used to quantify the presence of tremor and convulsions and, in some cases, was useful for precisely estimating time of death. The main finding indicates that in minipigs, as in other species, even relatively small differences in age can substantially alter the toxicity of nerve agents. Additionally, actigraphy can serve as a non-invasive method of characterizing the tremors and convulsions that often accompany nerve agent intoxication.

Raman measurements of substrate temperature in a molecular beam epitaxy growth chamber

A method is described for directly measuring the temperature of a substrate in a molecular-beam epitaxy (MBE) growth system. The approach relies on the establishment of the temperature dependence of Raman-active phonons of the substrate material using independently known calibration points across the range of interest. An unknown temperature in this range is then determined based on the Raman peak position with the substrate in situ the MBE chamber. The apparatus relies on conventional optics and Raman components. Shifting and broadening of the Raman spectrum are described based on the effects of thermal expansion and anharmonic decay. The choice of reference temperature is discussed. The method is qualified by examining the substrate temperature dependence, relative to that of a standard thermocouple, during a commonly used ramp procedure. Both temperature difference and time lag are obtained.

Novel technique for retroperitoneal implantation of telemetry transmitters for physiologic monitoring in Göttingen minipigs (Sus scrofa domesticus)

Telemetric monitoring of physiologic parameters in animal models is a critical component of chemical and biologic agent studies. The long-term collection of neurobehavioral and other physiologic data can require larger telemetry devices. Furthermore, such devices must be implanted in a location that is safe, well-tolerated, and functional. Göttingen minipigs (Sus scrofa domesticus) present an ideal large animal model for chemical agent studies due to their relatively small size, characterized health status, and ease of training and handling. We report an effective approach to implanting a novel device to measure transthoracic impedance to approximate respiratory tidal volume and rate in Suidae. We tested the approach using 24 male Göttingen minipigs. A ventral midline abdominal incision extending from the umbilicus to the prepuce was followed by a paramedian incision of the parietal peritoneum and dorsal blunt dissection to create a retroperitoneal pocket. The device was anchored inside the pocket to the internal abdominal musculature with 3-0 nonabsorbable suture, biopotential leads were routed through the abdominal musculature, and the pocket was closed with 3-0 absorbable suture. Paired biopotential leads were anchored intermuscularly at the level of the seventh rib midway between spine and sternum bilaterally to provide surrogate data for respiratory function. Postoperative recovery and gross pathology findings at necropsy were used to assess safety and refine the surgical procedure. Results demonstrated that this procedure permitted effective monitoring of complex physiologic data, including transthoracic impedance, without negatively affecting the health and behavior of the animals.

Use of operant performance to guide and evaluate medical treatment in an adult male cynomolgus macaque (Macaca fascicularis)

A 6-y-old male cynomolgus macaque presented with noticeable swelling of the left forearm and signs of discomfort, as indicated by nonuse of the arm even in a behavioral task that he previously had been well-motivated to perform. Examination under anesthesia revealed lacerations to the arm. Radiography of the forearm showed no fractures, indicating that the damage was limited to soft tissue. The daily operant behavioral session assessed the amount of force the monkey emitted when touching the screen with the affected arm and how long each touch was sustained. We then used these parameters (force and duration of touch) as objective measures of putative pain relief and recovery of function to guide the medical treatment. The affected monkey received ketoprofen, buprenorphine, or their combination but continued to perform poorly during daily operant behavioral sessions. Only after treatment with dexamethasone did performance return to preinjury levels, suggesting inflammation near the radial or ulnar nerve. These findings indicate that performance of a trained operant task performance can be useful in guiding medical treatment, evaluating pain relief, and objectively monitoring health in laboratory animals.

Stimulus-food pairings produce stimulus-directed touch-screen responding in cynomolgus monkeys (macaca fascicularis) with or without a positive response contingency

Acquisition and maintenance of touch-screen responding was examined in naïve cynomolgus monkeys (Macaca fascicularis) under automaintenance and classical conditioning arrangements. In the first condition of Experiment 1, we compared acquisition of screen touching to a randomly positioned stimulus (a gray square) that was either stationary or moving under automaintenance (i.e., banana pellet delivery followed an 8-s stimulus presentation or immediately upon a stimulus touch). For all subjects stimulus touching occurred within the first session and increased to at least 50% of trials by the end of four sessions (320 trials). In the subsequent condition, stimulus touching further increased under a similar procedure in which pellets were only delivered if a stimulus touch occurred (fixed ratio 1 with 8-s limited hold). In Experiment 2, 6 naive subjects were initially exposed to a classical conditioning procedure (8-s stimulus preceded pellet delivery). Despite the absence of a programmed response contingency, all subjects touched the stimulus within the first session and responded on about 50% or more of trials by the second session. Responding was also sensitive to negative, neutral, and positive response contingencies introduced in subsequent conditions. Similar to other species, monkeys engaged in stimulus-directed behavior when stimulus presentations were paired with food delivery. However, stimulus-directed behavior quickly conformed to response contingencies upon subsequent introduction. Video recordings of sessions showed topographies of stimulus-directed behavior that resembled food acquisition and consumption.

Systemic administration of the potential countermeasure huperzine reversibly inhibits central and peripheral acetylcholinesterase activity without adverse cognitive-behavioral effects

Huperzine A is potentially superior to pyridostigmine bromide as a pretreatment for nerve agent intoxication because it inhibits acetylcholinesterase both peripherally and centrally, unlike pyridostigmine, which acts only peripherally. Using rhesus monkeys, we evaluated the time course of acetylcholinesterase and butyrylcholinesterase inhibition following four different doses of -(-)huperzine A: 5, 10, 20, and 40 microg/kg. Acetylcholinesterase inhibition peaked 30 min after intramuscular injection and varied dose dependently, ranging from about 30% to 75%. Subsequently, cognitive-behavioral functioning was also evaluated at each dose of huperzine A using a six-item serial-probe recognition task that assessed attention, motivation, and working memory. Huperzine did not impair performance, but physostigmine did. The results demonstrate that huperzine A can selectively and reversibly inhibit acetylcholinesterase without cognitive-behavioral side effects, thus warranting further study.

WITHDRAWN: Effects of repeated sublethal VX exposure on operant time estimation in rats

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Bioscavenger for protection from toxicity of organophosphorus compounds

Current antidotal regimens for organophosphorus compound (OP) poisoning consist of a combination of pretreatment with a spontaneously reactivating AChE inhibitor such as pyridostigmine bromide, and postexposure therapy with anticholinergic drugs such as atropine sulfate and oximes such as 2-PAM chloride (Gray, 1984). Although these antidotal regimens are effective in preventing lethality of animals from OP poisoning, they do not prevent postexposure incapacitation, convulsions, performance deficits, or, in many cases, permanent brain damage (Dunn and Sidell, 1989). These problems stimulated the development of enzyme bioscavengers as a pretreatment to sequester highly toxic OPs before they reach their physiological targets. Several studies over the last two decades have demonstrated that exogenously administered human serum butyrylcholinesterase (Hu BChE) can be used successfully as a safe, efficacious, and single prophylactic treatment to counteract the toxicity of OPs. It also has potential use for first responders (civilians) reacting to terrorist nerve gas release, pesticide overexposure, or succinylcholine-induced apnea. A dose of 200 mg of Hu BChE in humans is envisioned as a prophylactic treatment that can protect from exposure of 2-5 x LD50 of nerve agents (Ashani, 2000).

Serial-probe recognition in rhesus macaques: effects of midazolam

A serial-probe recognition task was used to assess the effects of midazolam on visual attention and short-term memory in three rhesus monkeys. On each trial, six unique alphanumeric sample stimuli (list items) were presented sequentially followed by a choice period. Choosing the 'probe' stimulus was correct if the probe matched one of the list items; otherwise, choosing the 'default' stimulus (a white square) was correct. Behavior was examined under a range of doses of midazolam (0.065, 0.13, 0.26, and 0.52 mg/kg IM). Midazolam did not significantly reduce choice accuracy or change the shape of the serial position function and did not significantly reduce choice responding. However, choice reaction time was significantly increased by the two highest doses of midazolam. Responding directed at the sample stimuli was reduced at the two highest doses of midazolam. Furthermore, 0.52 mg/kg midazolam significantly increased sample-stimulus reaction time at all six serial positions. Overall, these data suggest that the two highest doses of midazolam tested increase reaction time, but do not directly impair short-term visual recognition memory. This is noteworthy because such doses appear capable of protecting against nerve agent-induced seizures.

Effects of physostigmine and human butyrylcholinesterase on acoustic startle reflex and prepulse inhibition in C57BL/6J mice

The use of exogenously administered cholinesterases as bioscavengers of highly toxic organophosphorus nerve agents is a viable prophylactic against this threat. To use this strategy, cholinesterases must provide protection without disrupting behavior when administered alone. To assess behavioral safety, the acoustic startle reflex and prepulse inhibition (PPI) of C57BL/6J mice were investigated following administration of human plasma-derived butyrylcholinesterase (HuBChE). Two hours before testing, four groups of mice (n=10 per group) were pretreated with saline or HuBChE (2000 U, ip). Fifteen minutes before testing, subjects received either saline or the carbamate physostigmine (0.4 mg/kg, sc). Mice exposed to physostigmine exhibited a significant attenuation of the startle reflex, an increased time to peak startle amplitude, and significantly increased PPI. This effect was partially mitigated in mice pretreated with HuBChE. HuBChE alone did not change startle behavior or PPI significantly compared to saline controls. The circulatory time-course of butyrylcholinesterase was assessed in a separate group of mice and revealed levels approximately 600 times the physiological norm 2-4 h post administration. Thus, HuBChE does not appear to significantly alter startle or PPI behavior at a dose 30-fold higher than that estimated to be necessary for protection against 2LD50 of soman in humans.

Recovery from ischemic brain injury in the rat following a 10 h delayed injection with MLN519

In the present study, we evaluated delayed treatment effects of the proteasome inhibitor and anti-inflammatory agent MLN519 (initiated 10 h post-injury) to improve recovery following ischemic brain injury in rodents. Male rats were exposed to 2 h of middle cerebral artery occlusion (MCAo) and treated with MLN519 (1.0 mg/kg, i.v. @ 10, 24, and 48 h post-occlusion) or vehicle. By 2 weeks post-injury, 60% (6/10) of vehicle animals survived, which was improved (although non-significantly) to 78% (7/9) following MLN519 treatment. The percent loss of tissue in the ipsilateral brain hemisphere (at 2 weeks) was significantly reduced from 27+/-4% (vehicle) to 15+/-4% (MLN519). MLN519 treated animals also lost significantly less body weight (39%) and showed significant improvement in overall neurological function across the 2-week recovery period. However, no significant treatment effects were observed to reduce foot-fault deficits (balance beam) or improve recovery of operant performance (active avoidance test). Overall, delayed treatment with MLN519 provided significant improvement in 3 of 6 test metrics (histopathology, body weight, and neurological dysfunction) supporting improved outcome for brain-injured subjects.

Air and shock two-way shuttlebox avoidance in C57BL/6J and 129X1/SvJ mice

Despite multiple advantages of the use of electric shock as an aversive stimulus, reasons exist for considering alternative aversive stimuli. In the present study, we examined and compared the acquisition of two-way shuttlebox avoidance with 275.8-kPa (40-psi) pulsed air and continuous 0.4-mA shock in two strains of mice commonly employed in targeted gene mutation research, C57BL/6J and 129X1/SvJ. Each trial consisted of a 5-s warning stimulus (WS, light) during which shuttling to the other side cancelled delivery of the aversive stimulus. Once initiated, the aversive stimulus remained active for 20 s or until an escape response occurred. For C57BL/6J mice, air and shock were equally and highly effective aversive stimuli. In contrast, air was less effective than shock for 129X1/SvJ mice. C57BL/6J mice outperformed 129X1/SvJ mice for both stimulus types. For 129X1/SvJ mice, longer escape latencies were observed initially for air, suggesting that shock is more effective. However, these differences in latency dissipated within the first seven sessions. Nevertheless, by the end of the 17-day study, asymptotic levels of avoidance proficiency were substantially lower for air than for shock in 129X1/SvJ mice. These results indicate that air is a suitable substitute for shock as an aversive stimulus in shuttlebox active avoidance; however, the relative efficacies of these aversive stimuli appear to depend upon the strain chosen for study.

Effects of anticholinergics on serial-probe recognition accuracy of rhesus macaques (Macaca mulatta)

Potential deleterious behavioral effects of the anticholinergics biperiden and scopolamine were examined via the performance of rhesus monkeys on a serial-probe recognition (SPR) procedure. On each trial, six unique stimuli (list items) were presented sequentially followed by a choice phase. In the choice phase, two stimuli were presented, a standard or 'default' stimulus (a white rectangle) and a 'probe' stimulus that differed with each choice trial. Choosing the probe stimulus was considered correct if the probe matched one of the list items; otherwise, choosing the default stimulus was considered correct. Behavior was examined under a range of doses of biperiden (0.001-1.0 mg/kg) and scopolamine (0.0056-0.03 mg/kg). Scopolamine (0.01-0.03 mg/kg) and biperiden (0.3-1.0 mg/kg) reduced overall accuracy. At the highest dose, scopolamine, but not biperiden, reduced the number of trials completed per session. The results suggest that doses of scopolamine and biperiden necessary to prevent or eliminate organophosphate induced seizures may affect performance adversely. However, because the degree of impairment from biperiden was modest, further examination of this anticonvulsant may be warranted.

Two recessive gene inheritance for triallate resistance in Avena fatua L

Extensive use of the preemergence herbicide triallate over the last three decades has selected for resistant (R) Avena fatua L. populations in several areas of the United States and Canada. R plants are also cross-resistant to the unrelated pyrazolium herbicide difenzoquat. We made reciprocal crosses between inbred R and susceptible (S) lines to determine the genetic basis of triallate resistance. Seeds from parental lines and F(2) populations were treated with soil applications of 0.275, 0.55, or 1.1 kg/ha triallate in the greenhouse and plant heights recorded after 37 days. Surviving F(2) plants were selfed and the resulting F(3) families were screened with 1.1 kg/ha triallate. In the F(2) populations, assortment of S and R phenotypes fit a 15:1 segregation ratio, suggesting that resistance was controlled by the two independently segregating recessive genes TRR1 and TRR2. None of the 912 F(3) progeny from 51 R F(2) individuals was susceptible to triallate treatment, further supporting a two-gene mode of inheritance. There was a possible maternal effect on susceptibility at the highest triallate rate tested.

Efficient translation initiation is required for replication of bovine viral diarrhea virus subgenomic replicons

An internal ribosome entry site (IRES) mediates translation initiation of bovine viral diarrhea virus (BVDV) RNA. Studies have suggested that a portion of the N(pro) open reading frame (ORF) is required, although its exact function has not been defined. Here we show that a subgenomic (sg) BVDV RNA in which the NS3 ORF is preceded only by the 5' nontranslated region did not replicate to detectable levels following transfection. However, RNA synthesis and cytopathic effects were observed following serial passage in the presence of a noncytopathic helper virus. Five sg clones derived from the passaged virus contained an identical, silent substitution near the beginning of the NS3 coding sequence (G400U), as well as additional mutations. Four of the reconstructed mutant RNAs replicated in transfected cells, and in vitro translation showed increased levels of NS3 for the mutant RNAs compared to that of wild-type (wt) MetNS3. To more precisely dissect the role of these mutations, we constructed two sg derivatives: ad3.10, which contains only the G400U mutation, and ad3.7, with silent substitutions designed to minimize RNA secondary structure downstream of the initiator AUG. Both RNAs replicated and were translated in vitro to similar levels. Moreover, ad3.7 and ad3.10, but not wt MetNS3, formed toeprints downstream of the initiator AUG codon in an assay for detecting the binding of 40S ribosomal subunits and 43S ribosomal complexes to the IRES. These results suggest that a lack of stable RNA secondary structure(s), rather than a specific RNA sequence, immediately downstream of the initiator AUG is important for optimal translation initiation of pestivirus RNAs.

Identification of nucleocapsid protein residues required for Sendai virus nucleocapsid formation and genome replication

Alanine substitution mutations in the Sendai virus nucleocapsid (NP) protein have defined highly conserved hydrophobic and charged residues from amino acids (aa) 362 to 371 that are essential for function of the protein in RNA replication. Mutant NP362, which had the change F362A, was incapable of supporting in vitro RNA replication. NP362 expressed alone formed extended oligomers which exhibited an abnormal morphology and density suggesting that these particles were not associated with any RNA. Mutant NP364, which had changes L362A and G365A, was also inactive in RNA replication; however, this was because the protein was unstable and did not form NP-NP complexes. Mutant NP370 mutant, which had changes K370A and D371A, was inactive in in vitro replication, although it could form the required NP0-P and NP-NP protein complexes. The self-assembled nucleocapsid-like particles formed by NP370 alone had a morphology like that of wild-type NP and banded in CsCl as ribonucleoprotein particles, suggesting that they contained cellular RNA. These data suggest that the replication defect of NP370 may be in the ability to specifically encapsidate Sendai virus genome RNA. Mutant NP373, where nonconserved charged residues at aa 373 and 375 were substituted with alanine, gave a wild-type phenotype. Thus these amino acids are not required for either protein-protein interactions or in vitro Sendai virus RNA replication.

A highly conserved region of the Sendai virus nucleocapsid protein contributes to the NP-NP binding domain

The nucleocapsid protein (NP) of Sendai virus is an essential component of both the nucleocapsid template and the NP-NP and NP0-P protein complexes required for viral RNA replication. When expressed alone in mammalian cells NP self-assembles into nucleocapsid-like particles which appear to contain cellular RNA. To identify putative NP-NP binding domains, fusions between the monomeric maltose-binding protein (MBP) and portions of NP were constructed. The fusion proteins which contain the central conserved region (CCR) (amino acids 258-357, MBP-NP1) and the N-terminal 255 amino acids (MBP-NP2) of NP both oligomerized, suggesting that these regions contain sequences important for NP-NP self-assembly. In addition, the MBP-NP1 fusion protein can function as an inhibitor of viral RNA replication. Complementary studies involving site-directed mutagenesis of the full-length NP protein have identified specific residues in the CCR which are essential for viral RNA replication in vitro. Two such replication-negative mutants, F324V and F324I, were defective in self-assembly, suggesting that the Phe residue at amino acid 324 is essential for the NP-NP interaction. A third mutant, NP260-1 (Y260D), self-assembled to form aberrant oligomers which exhibit an unusual helical structure and appear to lack any associated RNA. The mutants NP299-5 (L299I and I300V) and NP313-2 (I313F), in contrast, appear to form all the required protein complexes, but were inactive in viral RNA replication, suggesting that interactions specifically with Sendai RNA were disrupted. These data have thus identified specific residues in the CCR of the native NP protein which appear to be important for NP-NP or NP-RNA interactions and for genome replication.

An amino-terminal domain of the Sendai virus nucleocapsid protein is required for template function in viral RNA synthesis

The nucleocapsid protein (NP) of Sendai virus encapsidates the genome RNA, forming a helical nucleocapsid which is the template for RNA synthesis by the viral RNA polymerase. The NP protein is thought to have both structural and functional roles, since it is an essential component of the NP0-P (P, phosphoprotein), NP-NP, nucleocapsid-polymerase, and RNA-NP complexes required during viral RNA replication. To identify domains in the NP protein, mutants were constructed by using clustered charge-to-alanine mutagenesis in a highly charged region from amino acids 107 to 129. Each of the mutants supported RNA encapsidation in vitro. The product nucleocapsids formed with three mutants, NP114, NP121, and NP126, however, did not serve as templates for further amplification in vivo, while NP107, NP108, and NP111 were nearly like wild-type NP in vivo. This template defect in the NP mutants from amino acids 114 to 129 was not due to a lack of NP0-P, NP-NP, or nucleocapsid-polymerase complex formation, since these interactions were normal in these mutants. We propose that amino acids 114 to 129 of the NP protein are required for the nucleocapsid to function as a template in viral genome replication.

Adenocarcinoma in situ of the uterine cervix: management and outcome

OBJECTIVE

To retrospectively review the management of adenocarcinoma in situ of the uterine cervix, to determine the outcome of conization versus hysterectomy, and to compare the results achieved by different methods of conization.

METHODS

We performed a retrospective pathology and chart review of 46 patients with cervical adenocarcinoma in situ from January 1980 to October 1994.

RESULTS

Nine patients were managed during the first half of the study period and 37 were managed in the second half. The mean age of patients was 38.4 years (range 25-72). Forty-five of 46 patients were diagnosed as a result of an abnormal Pap smear, although only 19 smears indicated adenocarcinoma in situ or other glandular abnormalities. Cold knife conization resulted in a 33% rate of positive margins for adenocarcinoma in situ compared to 50% for large loop excision of the transformation zone (LLETZ). Among 24 conservatively managed patients with negative conization margins, there have been 2 (8.3%) recurrences of adenocarcinoma in situ. Among patients not undergoing hysterectomy as definitive treatment, 1 of 18 (6%) patients undergoing cold knife conization recurred, compared to 4 of 14 (29%) managed with LLETZ, despite a 63.4-month shorter mean follow-up interval for the LLETZ patients.

CONCLUSIONS

Cold knife conization is associated with a lower rate of recurrence of cervical adenocarcinoma in situ compared to LLETZ. We recommend cold knife conization for patients who are not treated with hysterectomy.

A medical care program for Ethiopian Jewish migrants in Addis Ababa

In May 1990, the Ethiopian Jews--who for centuries had lived as peasants in isolated rural villages in northwestern Ethiopia--migrated en masse to Addis Ababa. In July, 39 deaths occurred in this community of approximately 22,000 people. When this was reported in Israel the Ethiopian Jews already living there staged a demonstration at the Knesset claiming that their relatives in Ethiopia were being neglected by the Jewish organizations providing aid to the Ethiopian people. In response, the American Jewish Joint Distribution Committee rapidly developed a comprehensive medical program during a 3-week period commencing on August 20. During the ensuing months there was a rapid fall in the mortality rate in the Jewish community. On 24-25 May 1991, as rebel armies were preparing to enter the city, almost the entire Jewish population remaining in Ethiopia was airlifted to Israel.