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W A Hunt

Publications and source records attributed to W A Hunt.

At least 19 recordsLinked to original sources

Research perspectives on alcohol craving: an overview.

This overview of the Addiction supplement on 'Research Perspectives on Alcohol Craving' has three objectives. The first is to familiarize readers with the variety of theoretical models relevant to craving and the definitions of craving generated by them that are discussed in the supplement. These include phenomenological models, classical and operant conditioning models, the incentive-sensitization theory, a tonic-phasic model of dopamine system regulation, cognitive social learning theory and the cognitive processing theory of craving. The second objective is to provide a brief summary of the methodological articles which focus as a whole more on what can be done than on what has been done in alcohol craving research. The final objective is to emphasize the potential importance of transdisciplinary research--research that integrates components of different theoretical models--for delineating the role of alcohol and drug craving in the complex biobehavioral process known as addiction. It is the hope of the guest editors (the authors of this overview) that the Addiction supplement and this introduction to it will contribute to development of a framework for future transdisciplinary research on alcohol craving.

Alcohol-Related Disorders↗

Craving research: future directions.

Many prospective clinical studies have concluded that craving does not reliably predict relapse and that the concept is of little or no clinical utility. Contrary to earlier more simplistic clinical models of addiction, more recent models do not require that craving be present for relapse to occur. New approaches to study human craving may enhance its predictive validity and yield more knowledge of its nature, course, behavioural sequelae and regulatory function in alcohol/drug consumption. These approaches include empirical research that focuses on: (1) the elucidation of the domains of craving (i.e. subjective experience, physiological responses, behavioural sequelae and their inter-relationships); (2) the temporal dynamics of craving (i.e. its course over minutes or days, as well as its natural history over the course of a drinking career); (3) the factors that may mediate/moderate/determine the development and resolution of craving; (4) studies of the predictive validity of craving measures; and (5) the development of valid methods of measuring the different domains of craving. The conclusions are that future craving research should: (1) incorporate more sophisticated general theories of behaviour (conditioning, cognitive social learning, neurobiological, and genetic); (2) apply more sophisticated and standardized measurement methods and experimental paradigms, including studies in which alcohol is made available to human subjects; and (3) effective development of new pharmacological and behavioural therapies for relapse prevention depend on greater understanding of the nature and measurement of craving.

Behavior, Addictive↗

Cefazolin in chronic hemodialysis patients: a safe, effective alternative to vancomycin.

Vancomycin use is common in hemodialysis patients, due in part to the ease of dosing, but can lead to the development of resistant organisms, including vancomycin-resistant enterococcus. Alternate antibiotics may be equally effective and allow similar dosing in the chronic hemodialysis population. A retrospective review of culture results from a 217-patient, non-hospital-based outpatient hemodialysis center was performed over a 7-month period. Wound and blood culture sensitivity to cefazolin, vancomycin, cefazolin plus gentamicin, and vancomycin plus gentamicin was analyzed. Cefazolin was equivalent to vancomycin for empiric treatment of clinically significant infections in a population with a low rate of methicillin-resistant Staphylococcus aureus infection. Cefazolin plus gentamicin was superior to vancomycin alone. The vancomycin plus gentamicin combination did provide minimally broader coverage than the cefazolin plus gentamicin combination. A prospective pharmacokinetic analysis of postdialysis cefazolin dosing was performed in anuric chronic hemodialysis patients dialyzed with polysulfone dialyzers. Peak, predialysis, and postdialysis cefazolin levels were obtained. Nondialysis clearance of cefazolin was sufficiently low (k(e), 0.027; t(1/2), 26.4 hours) and dialysis clearance sufficiently high (k(e), 0.254; t(1/2), 3.19 hours) to provide for safe and effective peak and trough cefazolin levels with postdialysis dosing in anuric hemodialysis patients. In conclusion, cefazolin alone or with gentamicin in an appropriate empiric antibiotic choice in chronic hemodialysis patients dialyzed in a nonhospital setting with low methicillin-resistant S. aureus infection rates. For infections with documented sensitivity to cefazolin, a 1 g intravenous dose postdialysis (750 mg in patients weighing <50 kg) is safe and effective.

Ambulatory Care↗

Behavioral endpoints for radiation injury.

The relative behavioral effectiveness of heavy particles was evaluated. Using the taste aversion paradigm in rats, the behavioral toxicity of most types of radiation (including 20Ne and 40Ar) was similar to that of 60Co photons. Only 56Fe and 93Nb particles and fission neutrons were significantly more effective. Using emesis in ferrets as the behavioral endpoint, 56Fe particles and neutrons were again the most effective; however, 60Co photons were significantly more effective than 18 MeV electrons. These results suggest that LET does not completely predict behavioral effectiveness. Additionally, exposing rats to 10 cGy of 56Fe particles attenuated amphetamine-induced taste aversion learning. This behavior is one of a broad class of behaviors which depends on the integrity of the dopaminergic system and suggests the possibility of alterations in these behaviors following exposure to heavy particles in a space radiation environment.

Amphetamine↗

Exposure to heavy charged particles affects thermoregulation in rats.

Rats exposed to 0.1-5 Gy of heavy particles (56Fe, 40Ar, 20Ne or 4He) showed dose-dependent changes in body temperature. Lower doses of all particles produced hyperthermia, and higher doses of 20Ne and 56Fe produced hypothermia. Of the four HZE particles, 56Fe particles were the most potent and 4He particles were the least potent in producing changes in thermoregulation. The 20Ne and 40Ar particles produced an intermediate level of change in body temperature. Significantly greater hyperthermia was produced by exposure to 1 Gy of 20Ne, 40Ar and 56Fe particles than by exposure to 1 Gy of 60Co gamma rays. Pretreating rats with the cyclo-oxygenase inhibitor indomethacin attenuated the hyperthermia produced by exposure to 1 Gy of 56Fe particles, indicating that prostaglandins mediate 56Fe-particle-induced hyperthermia. The hypothermia produced by exposure to 5 Gy of 56Fe particles is mediated by histamine and can be attenuated by treatment with the antihistamines mepyramine and cimetidine.

Alpha Particles↗

Neuroscience research: how has it contributed to our understanding of alcohol abuse and alcoholism? A review.

Alcohol abuse and alcoholism are the greatest substance abuse problems in the United States today and contribute to numerous medical and social problems. To deal with many of these problems, an understanding of how alcohol acts on the brain is extremely important. Advances in neuroscience research have provided significant clues about where and how alcohol works on the brain. Alcohol clearly acts on membrane function, altering such processes as ion movements and neurotransmitter interactions with their receptors. Although these alcohol-induced alterations are presumed to relate to changes in behavior, this has not been clearly established. However, alcohol research is on the threshold of making a giant leap forward in our understanding the etiology of alcoholism.

Alcohol Drinking↗

Deficits in the sensitivity of striatal muscarinic receptors induced by 56Fe heavy-particle irradiation: further "age-radiation" parallels.

We had previously shown that there was a loss of sensitivity of muscarinic receptors (mAChR) to stimulation by cholinergic agonists (as assessed by examining oxotremorine enhancement of K(+)-evoked release of dopamine from neostriatal slices) in animals that had been exposed to energetic particles (56Fe, 600 MeV/n), an important component of cosmic rays. This loss of mAChR sensitivity was postulated to be the result of radiation-induced alterations in phosphoinositide-mediated signal transduction. The present experiments were undertaken as a first step toward determining the locus of these radiation-induced deficits in signal transduction by examining K+ enhancement of release of dopamine in 56Fe-exposed animals (0, 0.1, and 1.0 Gy) with agents [A23187, a potent Ca2+ ionophore, or 1,4,5-inositol trisphosphate (IP3)] that "bypass" the mAChR-G protein interface and by comparing the response to oxotremorine-enhanced K(+)-evoked release of dopamine. Results showed that although oxotremorine-enhanced K(+)-evoked release of dopamine was reduced significantly in the radiation groups, no radiation effects were seen when A23187 or IP3 was used to enhance K(+)-evoked release of dopamine. Since similar findings have been observed in aging, the results are discussed in terms of the parallels between aging and radiation effects in signal transduction that might exist in the neostriatum.

Aging↗

Relationship between vomiting and taste aversion learning in the ferret: studies with ionizing radiation, lithium chloride, and amphetamine.

The relationship between emesis and taste aversion learning was studied in ferrets (Mustela putorius furo) following exposure to ionizing radiation (50-200 cGy) or injection of lithium chloride (1.5-3.0 mEq/kg, ip). When 10% sucrose or 0.1% saccharin was used as the conditioned stimulus, neither unconditioned stimulus produced a taste aversion, even when vomiting was produced by the stimulus (Experiments 1 and 2). When a canned cat food was used as the conditioned stimulus, lithium chloride, but not ionizing radiation, produced a taste aversion (Experiment 3). Lithium chloride was effective in producing a conditioned taste aversion when administration of the toxin was delayed by up to 90 min following the ingestion of the canned cat food, indicating that the ferrets are capable of showing long-delay learning (Experiment 4). Experiment 5 examined the capacity of amphetamine, which is a qualitatively different stimulus than lithium chloride or ionizing radiation, to produce taste aversion learning in rats and cats as well as in ferrets. Injection of amphetamine (3 mg/kg, ip) produced a taste aversion in rats and cats but not in ferrets which required a higher dose (> 5 mg/kg). The results of these experiments are interpreted as indicating that, at least for the ferret, there is no necessary relationship between toxin-induced illness and the acquisition of a CTA and that gastrointestinal distress is not a sufficient condition for CTA learning.

Amphetamine↗

Emesis in ferrets following exposure to different types of radiation: a dose-response study.

Ferrets were exposed to gamma rays (60Co), fission neutrons, high-energy electrons (18.5 MeV) or iron particles (56Fe, 600 MeV/amu) in order to establish the dose-response relationships for emesis following exposure to different types of radiation. The results showed that the mean effective doses (ED50s) for iron particles (35 cGy) and neutrons (40 cGy) were similar. High-energy electrons were the least effective radiation, with an ED50 of 138 cGy. Gamma rays, with an ED50 of 95 cGy, showed an intermediate effectiveness. The results suggest that the relative effectiveness of different types of radiation generally increases with an increase in linear energy transfer (LET), although LET is not completely predictive of relative behavioral effectiveness.

Animals↗

Possible "accelerated striatal aging" induced by 56Fe heavy-particle irradiation: implications for manned space flights.

The present experiments were carried out to determine the effects of energy deposition from energetic iron (56Fe particles, an important component of cosmic rays) on motor behavioral performance and to determine if the observed deficits were caused by alterations in the neostriatum (an important motor control area). Neostriatal function was assessed with two correlated parameters, i.e., motor behavioral performance (wire suspension task), and oxotremorine-enhanced K(+)-evoked release of dopamine from perifused striatal slices. Rats were exposed to one of several doses of 56Fe-particle irradiation (0.10-1.0 Gy) and tested on a wire suspension task at 3-180 days postirradiation. Results indicated that profound decrements occurred in both of these indices. The effects on K(+)-evoked release of dopamine were evident for as long as 180 days after irradiation, and a subsequent experiment indicated that these effects appeared as early as 12 h postirradiation. Since similar findings have been observed in aged rats, the results are discussed in terms of these particles producing a possible accelerated striatal aging effect.

Aging↗

Relationship between linear energy transfer and behavioral toxicity in rats following exposure to protons and heavy particles.

Rats were exposed to protons (155 MeV) or to helium (165 MeV/amu), neon (522 MeV/amu) or argon (670 MeV/amu) particles to evaluate the behavioral toxicity of these types of radiations. Behavioral toxicity was assessed using the conditioned taste aversion paradigm. Exposure to all types of radiation produced dose-dependent increases in the intensity of the acquired taste aversion. However, the intensity of the aversions, measured as the dose that produced a 50% decrease in the intake of the sucrose-conditioned stimulus, did not show significant variation as a function of the linear energy transfer (LET) of the radiation. The results are discussed in terms of the relationship between LET and behavioral toxicity.

Animals↗

Reductions in calcium uptake induced in rat brain synaptosomes by ionizing radiation.

Gamma irradiation (60Co) reduced KCl-stimulated voltage-dependent 45Ca2+ uptake in whole-brain, cortical, and striatal synaptosomes. The time course (3, 10, 30, and 60 s) of calcium uptake by irradiated (3 Gy) and nonirradiated synaptosomes, as well as the effect of KCl (15-65 mM), was measured in whole-brain synaptosomes. The fastest and highest rate of depolarization-dependent calcium uptake occurred at 3 s with 65 mM KCl. Irradiation reduced calcium uptake at all incubation times and KCl concentrations. Bay K 8644 enhancement of KCl-stimulated calcium influx was also reduced by radiation exposure. Nimodipine binding to dihydropyridine (DHP) L-type calcium channel receptors was not altered following radiation exposure. These results demonstrate an inhibitory effect of ionizing radiation on the voltage-sensitive calcium channels in rat brain synaptosomes that are not mediated by DHP receptors.

Animals↗

Role of neurotensin in radiation-induced hypothermia in rats.

The role of neurotensin in radiation-induced hypothermia was examined. Intracerebroventricular (ICV) administration of neurotensin produced dose-dependent hypothermia. Histamine appears to mediate neurotensin-induced hypothermia because the mast cell stabilizer disodium cromoglycate and antihistamines blocked the hypothermic effects of neurotensin. An ICV pretreatment with neurotensin antibody attenuated neurotensin-induced hypothermia, but did not attenuate radiation-induced hypothermia, suggesting that radiation-induced hypothermia was not mediated by neurotensin.

Animals↗

Arachidonic acid and prostaglandins enhance potassium-stimulated calcium influx into rat brain synaptosomes.

Exogenous administration of arachidonic acid, prostaglandins PGF2 alpha, PGD2 and PGE2 increased potassium-stimulated uptake of calcium in rat brain synaptosomes from the brain of the rat, but had no effect on the basal uptake of calcium. Arachidonic acid-induced uptake of calcium was mediated by its prostaglandin metabolites, because a cyclooxygenase inhibitor, indomethacin, inhibited the response. L-Type calcium channel blockers, such as verapamil, diltiazem and nimodipine, blocked both KCl- and prostaglandin-enhanced potassium-stimulated influx of calcium in the brain. These results suggest that prostaglandins act as a calcium ionophore, through L-type voltage-sensitive calcium channels.

Animals↗

Involvement of prostaglandins and histamine in radiation-induced temperature responses in rats.

Exposure of rats to 1-15 Gy of gamma radiation induced hyperthermia, whereas exposure to 20-150 Gy produced hypothermia. Since radiation exposure induced the release of prostaglandins (PGs) and histamine, the role of PGs and histamine in radiation-induced temperature changes was examined. Radiation-induced hyper- and hypothermia were antagonized by pretreatment with indomethacin, a cyclooxygenase inhibitor. Intracerebroventricular administration of PGE2 and PGD2 induced hyper- and hypothermia, respectively. Administration of SC-19220, a specific PGE2 antagonist, attenuated PGE2- and radiation-induced hyperthermia, but it did not antagonize PGD2- or radiation-induced hypothermia. Consistent with an apparent role of histamine in hypothermia, administration of disodium cromoglycate (a mast cell stabilizer), mepyramine (H1-receptor antagonist), or cimetidine (H2-receptor antagonist) attenuated PGD2- and radiation-induced hypothermia. These results suggest that radiation-induced hyperthermia is mediated via PGE2 and that radiation-induced hypothermia is mediated by another PG, possibly PGD2, via histamine.

Animals↗

Reduction of 3-methoxytyramine concentrations in the caudate nucleus of rats after exposure to high-energy iron particles: evidence for deficits in dopaminergic neurons.

Exposure to low doses of high-energy iron particles can alter motor behavior. The ability of rats to hang from a wire has been reported to be significantly degraded after exposure to doses as low as 0.5 Gy. In addition, deficits in the ability of acetylcholine to regulate dopamine release in the caudate nucleus (an area in the brain important for motor function) have been found. The concentrations of 3-methoxytyramine (3-MT), a metabolite of dopamine whose concentrations reflect dopamine release in vivo, were measured after rats were exposed to different doses of high-energy iron particles to gain further information about the effect of radiation on the dopaminergic system. Concentrations of 3-MT were significantly reduced 3 days after exposure to 5 Gy but returned to control values by 8 days. After 6 months, concentrations were again less than control values. Exposure to 5 Gy of high-energy electrons or gamma photons had no effect 3 days after exposure. Very high doses of electrons were needed to alter 3-MT concentrations. One hundred grays of electrons decreased 3-MT 30 min after irradiation but levels returned to control values by 60 min. Gamma photons had no effect after doses up to 200 Gy. These results provide further evidence that exposure to heavy particles can degrade motor behavior through an action on dopaminergic mechanisms and that this can occur after doses much lower than those needed for low-LET radiation.

3,4-Dihydroxyphenylacetic Acid↗

Insulin resistance in uremia: an in vivo and in vitro study.

Insulin-mediated glucose metabolism was examined in vivo and in vitro in a chronically uremic (4-week) rat model established by a 90% nephrectomy. Using the euglycemic insulin clamp technique, uremic rats demonstrated a 28% reduction (P less than .01) in total body glucose disposal compared with pair-fed controls. Suppression of hepatic glucose production by insulin was not impaired. The ability of insulin to promote glycogen synthesis by the soleus muscle in vitro was normal in uremic rats. In contrast, the ability of insulin to enhance both glycolysis and glucose oxidation by the soleus muscle was significantly reduced (P less than .01) in uremic rats. These results provide evidence that at least two intracellular metabolic defects, ie, in the glycolytic and glucose oxidative pathways, contribute to the insulin resistance of chronic uremia.

Animals↗