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Biomedical subjects

L A Parker

Publications and source records attributed to L A Parker.

At least 19 recordsLinked to original sources
PubMed1995

Chlordiazepoxide enhances the palatability of lithium-, amphetamine-, and saline-paired saccharin solution.

The ability of chlordiazepoxide to modify taste reactions elicited by a saccharin solution that was paired on three occasions with amphetamine (1 or 3 mg/kg), lithium (0.3 or 1.2 mEq/kg), or saline solution was assessed using the taste reactivity test. Chlordiazepoxide enhanced positive ingestive reactions regardless of the conditional properties of the tastant and had no effect on aversive reactions. These results support previous reports that chlordiazepoxide directly modifies the palatability of tastants.

Amphetamine↗
PubMed1995

Morphine-induced taste avoidance is attenuated with multiple conditioning trials.

Morphine has paradoxical effects in learning experiments. The drug can serve as a reinforcer in several situations; yet rats avoid tastes paired with morphine, much as they avoid tastes paired with an emetic drug such as lithium chloride (LiCl). The results of the present experiment indicate that, in contrast with LiCl-induced taste avoidance, the strength of morphine-induced avoidance is nonmonotonically related to the duration of training. Although taste avoidances produced by both drugs are readily established, the morphine-induced avoidance (unlike the LiCl-induced avoidance) weakens with continued flavor-drug pairings. These results, together with prior findings, suggest that there are distinctive features of morphine-induced taste avoidance.

Animals↗
PubMed1995

The effects of nicotine and nicotine withdrawal on taste reactivity.

The effect of nicotine pretreatment on the palatability of flavored solutions was assessed using the taste reactivity test. In Experiment 1, low doses of nicotine [0.2-0.4 mg/kg, subcutaneously (s.c.)] suppressed the aversive taste properties of quinine and quinine-sucrose mixture and enhanced the hedonic taste properties of sucrose (0.4 mg/kg, s.c.) in rats that were nicotine naive. In Experiment 2, rats were chronically preexposed to nicotine or saline over a period of 21 pretreatment days. Tolerance developed to the ability of nicotine to enhance the palatability of sucrose. Furthermore, rats that were chronically preexposed to nicotine displayed enhanced hedonic evaluation of sucrose 24 h after nicotine was withdrawn. These results confirm human self-reports that withdrawal from nicotine dependency enhances the palatability of sweet-tasting foods.

Animals↗
PubMed1995

Rewarding drugs produce taste avoidance, but not taste aversion.

Paradoxically, drugs that animals will self-administer also produce conditioned taste avoidance at similar dosage levels. The present review presents evidence that the taste avoidance produced by these rewarding drugs differs qualitatively from the taste avoidance produced by the nonrewarding, emetic drug, lithium chloride. An analysis of data pooled across 6 experiments compares the nature of flavor-drug associations produced by various rewarding drugs (amphetamine, cocaine, methamphetamine, methylphenidate, morphine, nicotine and phencyclidine) with that produced by lithium. The data from the groups conditioned with the rewarding drugs and with lithium were combined into the two categories of low/moderate and high doses. When assessed by the CTA test, the rewarding drugs did not differ from lithium in the strength of the CTA at low/moderate or at high doses. However, when assessed by the TR test, lithium produced more prominent aversive taste reactions than did the rewarding drugs. These findings suggest that the flavor-drug association produced by lithium and rewarding drugs differs qualitatively. With the large pooled data set we also assessed the relationship among the various TR categories, resulting in two factors of "Ingestion" and "Aversion" accounting for 55% of the total variability within the data.

Animals↗
PubMed1995

THC-induced place and taste aversions in Lewis and Sprague-Dawley rats.

The hedonic properties of delta-9-tetrahydrocannabinol (THC) were assessed in place and taste conditioning paradigms in both Lewis and Sprague-Dawley rat strains. THC produced place avoidance, taste avoidance, and aversive taste reactivity responses in both strains. The Lewis strain displayed more aversive taste reactions and a stronger taste avoidance when conditioned with lower doses of THC than did the Sprague-Dawley strain of rats. THC is an anomalous drug of abuse that appears to be aversive to rats when assessed by these measures.

Animals↗
PubMed1995

Necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is a disease characterized by ischemia and necrosis of the gastrointestinal tract frequently leading to perforation of the intestine. It occurs primarily in the premature infant and is a major cause of mortality and morbidity in the low birth weight infant. Careful nursing and medical care can greatly reduce the incidence and severity of this disease, thus decreasing both the associated morbidity and mortality. This article reviews the pathophysiology, diagnosis, and treatment of NEC; presents a case study; and provides a nursing care plan for treatment of this disease.

Enterocolitis, Pseudomembranous↗
PubMed1994

Pleural effusions: outpatient management with pigtail catheter chest tubes.

Pulmonary effusions associated with ovarian cancer indicate advanced disease. Although many patients tolerate these effusions, some are symptomatic and manifest respiratory distress. Therapeutic sclerosis of the pleural cavity is successful in some patients; however, not all patients are relieved of respiratory symptoms. We present two symptomatic patients in whom sclerosis was unsuccessful or not an option; their respiratory symptoms were relieved with placement of pigtail catheter chest tubes that allowed discharge from the hospital and management at home. Catheters were easy to manage at home and there were no infectious complications.

Aged↗
PubMed1994

Aversive taste reactivity: reactivity to quinine predicts aversive reactivity to lithium-paired sucrose solution.

The ability of a rat's reactivity to the aversive taste properties of quinine to predict its' reactivity to the aversive taste properties of a lithium-paired sucrose solution were assessed. In phase 1, all rats were intraorally infused with 0.05% quinine solution over a 2-min taste reactivity (TR) test. On the basis of their composite aversive reactions, rats were divided into high reactors (HiQ) and low reactors (LoQ). In phase 2, rats were given three TR conditioning/testing trials in which they received a 2-min intraoral infusion of 0.5 M sucrose solution immediately followed by an IP injection of either 127.2 mg/kg lithium chloride or physiological saline. Among rats conditioned with lithium during phase 2, the phase-1 quinine HiQs displayed more aversive reactions than did the phase-1 quinine LoQs. This suggests that reactivity to the aversive properties of quinine may predict the strength of conditioned palatability shifts to a lithium-paired sucrose solution.

Animals↗
PubMed1994

Fenfluramine-induced modification of palatability: analysis by the taste reactivity test.

The ability of various doses (0, 1.25, 2.5, and 5.0 mg/kg) of fenfluramine to modify the palatability of sucrose and quinine solutions was assessed by means of the taste reactivity test. Although fenfluramine did not modify the positive hedonic ingestive reactions elicited by sucrose solution, it consistently enhanced the negatively hedonic aversive reactions elicited by unpalatable 0.05% quinine solution and moderately palatable 2% sucrose solution. The results suggest that fenfluramine enhances the aversive properties of tastants without suppressing the positive hedonic properties of tastants. The results support a two-dimensional model of palatability.

Animals↗
PubMed1994

Individual differences in novelty-induced activity do not predict strength of amphetamine-induced place conditioning.

A rat's level of activity while in a novel chamber has been shown to predict the likelihood that rat will learn to self-administer low doses of amphetamine (10). In a series of four experiments employing the place conditioning paradigm, a rat's level of activity when placed in a novel chamber was used to predict its sensitivity to the rewarding properties of low doses of amphetamine. In phase 1 of each experiment, rats were divided into high responders (HRs) and low responders (LRs) on the basis of activity level while in a novel chamber. In phase 2, rats were given place conditioning trials (one to four trials) with amphetamine (0.75-10 mg/kg). Although amphetamine-induced place preferences were consistently demonstrated, activity in a novel chamber did not predict the strength of a preference formed for an amphetamine-paired place. The failure of these experiments to support similar investigations using the self-administration paradigm [e.g., (10)], suggests that caution be used in generalizing between paradigms believed to measure similar processes.

Amphetamine↗
PubMed1994

Abdominal CT findings in sarcoidosis: radiologic and clinical correlation.

PURPOSE: To estimate the prevalence of abdominal computed tomographic (CT) findings in sarcoidosis and to correlate these findings with those at chest radiography, clinical status, and level of angiotensin converting enzyme (ACE). MATERIALS AND METHODS: Abdominal CT examinations in 59 patients with sarcoidosis were evaluated for adenopathy, liver and spleen size, and discrete lesions within the liver or spleen. RESULTS: Extensive adenopathy was seen in 10% of patients. Marked hepatic and splenic enlargement was seen in 8% and 6%, respectively. Nodules were seen in the spleen in eight (15%) patients and in the liver in three (5%). Although liver size, spleen size, and adenopathy were directly related (P < .0001), the presence of nodules was not strongly related to organ size. Abdominal CT findings were related to clinical status and elevated ACE levels but not to chest radiographic stage. CONCLUSION: Marked abdominal CT findings are uncommon in sarcoidosis and correlate with disease activity but not chest radiographic stage.

Abdomen↗
PubMed1993

Rewarding and aversive properties of IP and SC cocaine: assessment by place and taste conditioning.

Three experiments were conducted to compare the effectiveness of intraperitoneally (IP) administered or subcutaneously (SC) administered cocaine to produce place and/or taste conditioning after four conditioning trials. In each experiment, IP (5-20 mg/kg) cocaine produced a place preference, but SC (0.5-20 mg/kg) cocaine at concentrations that prevented necrosis, did not produce a place preference. The failure of SC cocaine to produce a place preference was not a function of conditioning trial duration. On the other hand, SC cocaine (20 mg/kg) produced conditioned taste avoidance, but IP cocaine (20 mg/kg) did not produce conditioned taste avoidance. The results suggest that IP cocaine, but not SC cocaine, is rewarding.

Animals↗
PubMed1993

Fenfluramine-induced place aversion in a three-choice apparatus.

The hedonic properties of the anorectic agent fenfluramine (0.25, 1.0, 2.5, 5.0, and 10.0 mg/kg) were assessed in two experiments in a place conditioning paradigm. After four conditioning trials, rats were tested for their preference for a drug-paired chamber, saline-paired chamber, and a novel chamber. Fenfluramine produced a place aversion at doses of 2.5-10 mg/kg.

Animals↗
PubMed1993

Taste reactivity responses elicited by cocaine-, phencyclidine-, and methamphetamine-paired sucrose solutions.

The nature of flavor-drug associations produced by a range of doses of the reinforcing agents cocaine (5, 10, 15, 20, or 40 mg/kg sc), phencyclidine (0.5, 2, 10, or 20 mg/kg sc), and methamphetamine (2, 5, or 10 mg/kg ip) were assessed by the taste reactivity (TR) test and the conditioned taste avoidance (CTA) test. Even at the highest doses tested, none of the agents produced aversive TR responding. At doses that produced equivalent-strength CTA, lithium did establish aversive TR responding. These results provide evidence that drugs that serve as reinforcers in other paradigms produce conditioned flavor avoidance that is not motivated by a conditioned dislike for the flavor.

Animals↗
PubMed1993

The spleen and its vasculature in pancreatitis: CT findings.

The spleen and its vasculature are susceptible to damage from pancreatic inflammatory exudates. Fourteen patients were identified who demonstrated splenic or splenic vascular involvement from pancreatitis on computed tomography. Findings included intra- and perisplenic inflammatory fluid collections (n = 6), acute splenic hematomas (n = 3), splenic infarction (n = 1), splenic artery pseudoaneurysm (n = 1), and splenic vein thrombosis (n = 6). Eight of the 14 patients went on to urgent interventions including percutaneous catheter drainage (n = 2) and transcatheter embolotherapy (n = 6) based on the CT findings.

Aneurysm, False↗
PubMed1992

Naltrexone-induced aversions: assessment by place conditioning, taste reactivity, and taste avoidance paradigms.

The reinforcing/aversive properties of various doses of naltrexone (0.01, 1, and 10 mg/kg) were assessed in three experiments that employed place conditioning, taste reactivity, and taste avoidance paradigms. Naltrexone produced a place aversion and a taste aversion, but did not produce aversive taste reactivity responses, even at the highest dose (10 mg/kg) tested. This suggests that drugs that produce a place aversion do not necessarily produce a conditional dislike for a flavored solution with which they are paired.

Animals↗
PubMed1992

Place conditioning in a three- or four-choice apparatus: role of stimulus novelty in drug-induced place conditioning.

A series of 4 experiments examined the suggestion (Scoles & Siegel, 1986) that drug-induced place preference conditioning may be due to interference with habituation. In each experiment, rats had the opportunity to select among a drug-paired chamber, a saline-paired chamber, and a novel (or relatively novel) chamber. The drugs included the positively reinforcing drugs amphetamine, apomorphine, morphine, and nicotine and the aversive drug lithium chloride. The rats preferred chambers that were paired with amphetamine, apomorphine, and morphine more than chambers that were novel; however, they also consistently preferred novel chambers to familiar saline-paired chambers. There was no evidence of place conditioning with nicotine. The drug-induced place preference, but not the novelty preference, occurred after a single conditioning trial in a 3-choice apparatus but not a 4-choice apparatus. Lithium chloride established a place aversion after 1-3 conditioning trials. Measures of activity revealed that the rats were least active while in their most preferred chamber and most active while in their least preferred chamber.

Animals↗