Change overt

Toxicology. The acute oral and dermal toxicity of naphthalene is low with LD q values for rats from 1780—2500 mg/kg orally (41) and greater than 2000 mg/kg dermally. The inhalation of naphthalene vapors may cause headache, nausea, confusion, and profuse perspiration, and if exposure is severe, vomiting, optic neuritis, and hematuria may occur (28). Chronic exposure studies conducted by the NTP ia mice for two years showed that naphthalene caused irritation to the nasal passages, but no other overt toxicity was noted. Rabbits that received 1—2 g/d of naphthalene either orally or hypodermically developed changes ia the lens of the eye after a few days, foUowed by definite opacity of the lens after several days (41). Rare cases of such corneal epithelium damage ia humans have been reported (28). Naphthalene can be irritating to the skin, and hypersensitivity does occur. 

Animal behavior has been dehned by Odnm (1971) as the overt action an organism takes to adjnst to its environment so as to ensure its survival. A simpler definition is the dynamic interaction of an animal with its enviromnent (D Mello 1992). Another, more elaborate, one is, the outward expression of the net interaction between the sensory, motor arousal, and integrative components of the central and peripheral nervons systems (Norton 1977). The last dehnition spells out the important point that behavior represents the integrated function of the nervous system. Accordingly, disruption of the nervous system by neurotoxic chemicals may be expected to cause changes in behavior (see Klaasen 1996, pp. 466-467). 

Effects In Humans. Neither postmortem nor functional cerebrospinal fluid (CSF) studies in humans provide firm evidence for similar, long-term damages or alterations to monoaminergic neurons in chronic stimulant abusers. In part, the lack of demonstrable neurochemical changes may well be due to the obvious preclusion of well-controlled prospective experimentation in humans, as well as to variability in critical variables (e.g., individual sensitivity or pattern of abuse) encountered in clinical research. Possible relationship of the various complications of stimulant abuse including hyperpyrexia, seizure, anoxia, and metabolic exhaustion to neuronal chromatolysis, terminal destruction, and monoamine and enzymatic depletion have not been systematically explored in human autopsy eases. It should be also noted that, under nonperturbed conditions, overt behavioral deficits are rare in... 

Rats that have lost dopamine and/or serotonin terminals following treatment with amphetamine, methamphetamine, MDMA, MDA, / -chloroamphetamine, or fenfluramine show little in the way of overt ehanges in appearanee or behavior. Dr. Rieaurte (this volume) emphasized the need for more studies in primates, since MPTP-treated miee also show little in the way of observable functional changes, whereas MPTP-treated monkeys show marked neurologie deficits. It may be neeessary to do more detailed analysis of speeifie behaviors and other funetional outputs that are influeneed by dopamine and/or serotonin neurons, to detect functional deficits induced by some neurotoxic drugs. For instance, specific behaviors sueh as appetite-eontrolled behavior (Leibowitz and Shor-Posner 1986), murieidal behavior (Katz 1980), and sexual behavior (Tucker and File 1983) elieited by drugs... 

Similar constant checking across the cycle occurs in the Spider monkey (Ateles), where males directly sniff and nasally contact the females complex labial folds. The external genitalia lack visual peri-ovulatory alterations, hence usage of the AOS may occur. It is however unestablished in this, as in many other species without overt vulval colour change (Klein, 1971 Hunter et al., 1984). 

The interaction of ketamine with each of the three anticonvulsant compounds was also tested. Ketamine, 15 mg/kg, a dose showing no anti-PTZ effect and causing no overt behavioral changes, potentiated the effect of phenobarbital (20 mg/kg) in delaying the clonic and tonic convulsive responses and lethality (figure 3). Ketamine also potentiated the ability of phenytoin (20 mg/kg) to delay... 

The results demonstrate anticonvulsant properties of PCP and ketamine in two quite different seizure models. On the one hand, ketamine was effective in antagonizing several components of PTZ activity. Others have previously reported anti-PTZ effects of ketamine. However, the present results demonstrate that the anticonvulsant effects of ketamine against PTZ seizures closely resembled the effects of phenobarbital in that both compounds delayed clonic convulsions and prevented tonic extension. Moreover, a low dose of ketamine, which alone showed no anticonvulsant effect or overt behavioral changes, potentiated the anti-PTZ effects of phenobarbita 1. These findings suggest that ketamine possesses selective anticonvulsant properties. The anticonvulsant mechanism of action for phenobarbital is not known. However, the similarities between ketamine and phenobarbital, and the interaction between the two compounds, suggest a common mechanism or site of acti on. 

Interview the patient to determine if there is worsening or new symptoms related to VTE. Ask the patient about overt bruising or bleeding, particularly at the injection site, as well as changes in stool or urine color. 

Key study Blair et al. (1990a). Male and female B6C3Fj mice exposed to arsine at 0.5 ppm for 6 h exhibited no change in relative spleen weights or hematologic parameters and exhibited no overt signs of toxicity. 

---