Biomedical subjects

J A English

Publications and source records attributed to J A English.

17 recordsLinked to original sources

PubMed2001

Angiographic prevalence and clinical predictors of left subclavian stenosis in patients undergoing diagnostic cardiac catheterization.

The angiographic prevalence, clinical predictors, and sensitivity and specificity of a bilateral arm blood pressure differential for predicting proximal left subclavian artery stenosis were established in 492 patients undergoing cardiac catheterization. Seventeen subjects (3.5%) in the overall population and nine subjects (5.3%) with potential surgical coronary disease had proximal left subclavian stenosis. Precatheterization evidence of peripheral vascular disease (PVD) was the only predictor of subclavian stenosis in the overall population (P < 0.001; OR = 7.9; 95% CI = 2.6-24.3) and in patients with potential surgical coronary disease (P = 0.04; OR = 5.4; 95% CI = 1.1-27.2). Both a bilateral blood pressure differential of > 10 mm Hg and of > or =20 mm Hg had a good specificity but a poor sensitivity for predicting left subclavian stenosis. Thus, left subclavian angiography should be performed in patients with surgical coronary disease with either an arm blood pressure differential of > 10 mm Hg or with other precatheterization evidence of PVD. Cathet Cardiovasc Intervent 2001;54:8-11.

Aged↗

PubMed2000

LP-BM5 infection impairs spatial working memory in C57BL/6 mice in the Morris water maze.

Previous studies show that the LP-BM5 murine leukemia virus causes an acquired immunodeficiency syndrome in C57BL/6 mice (MAIDS) and impairs learning and memory without gross motor impairment. To assess spatial working memory impairment after LP-BM5 infection and the time course of this impairment, we tested mice in a modified working-memory version of the Morris water maze. Twenty mice were inoculated with LP-BM5; controls received medium (Minimum Essential Medium). In the test procedure, animals had two 1-min training sessions to learn the position of a randomly placed hidden platform. Thirty seconds after the second training session, animals were placed in the maze without the platform, and time and pathlength spent in each quadrant of the maze were measured. For 9 weeks after LP-BM5 infection, both groups showed preference for the target quadrant compared to the opposite quadrant. At 10 and 11 weeks after infection, the LP-BM5 virus infected mice lost this target quadrant preference. We conclude that LP-BM5 infection impaired spatial working memory in a modified working-memory version of the Morris water maze test in C57BL/6 mice at 10 and 11 weeks after virus infection.

Animals↗

PubMed2000

Sucrose and quinine intake by maternally-deprived and control rhesus monkeys.

Clinical depression is often characterized by a loss of interest or pleasure in formerly enjoyable activities. Analogs of anhedonia are established in rats, but the generality of this phenomenon to other species is unknown. Maternally-deprived rhesus macaques show a wide range of behavioral abnormalities that are reversed by chronic antidepressant treatment. We tested consumption by maternally deprived versus control macaques of sweetened (seven sucrose concentrations) or bitter water (four quinine concentrations) versus plain water to evaluate a non-human primate model of depression for signs of anhedonia. All monkeys consumed more sweetened than tap water, but maternally-deprived monkeys had a diminished preference for sweetened water than did controls. However, maternally deprived animals consumed more bitter water than did controls. Baseline fluid consumption did not differ. The data suggest that 'anhedonia' in animal models may be secondary to a generally attenuated responsiveness to stimuli, rather than a unitary reduction in responsiveness to the appetitive properties of stimuli. We conclude that maternally-deprived rhesus monkeys do not display gustatory signs of anhedonia, but rather of insensitivity to gustatory stimuli.

Animals↗

PubMed1999

Increased discriminative stimulus potency of phencyclidine in C57B1/6 mice infected with the LP-BM5 retrovirus.

Drug discrimination procedures in mice are used to study the neuropharmacology of a wide variety of drugs. In C57 B1/6 mice, infection with the LP-BM5 murine leukemia virus leads to a syndrome (murine acquired immunodeficiency syndrome-MAIDS) characterized by immunocompromise, neurochemical alterations, and learning and memory deficits. Because the neurochemical and behavioral changes suggest that altered glutamatergic neurotransmission follows LP-BM5 infection, we studied the effects of infection on discriminative stimulus properties of phencyclidine (PCP), a Ca2+ channel blocker at NMDA receptors. We also tested D-amphetamine and dizocilpine to assess the specificity of the discrimination. As expected, dizocilpine produced PCP-like responding. After animals were trained to discriminate PCP from saline, they were inoculated with LP-BM5 and the PCP dose-response functions repeatedly determined. The potency of PCP in this procedure was unchanged 3 weeks after infection, but was increased approximately fivefold 6 and 9 weeks after infection. Amphetamine 9 weeks after inoculation did not produce PCP-like responding, showing that the results were not caused by a loss of specificity of the discrimination. The time course for changes in PCP potency is similar to those of other behavioral and neurochemical changes reported after LP-BM5 infection. The results are consistent with an action of LP-BM5 infection at glutamatergic synapses.

Adrenergic Agents↗

PubMed1998

LP-BM5 infection impairs acquisition, but not performance, of active avoidance responding in C57B1/6 mice.

LP-BM5 murine leukemia virus infection causes an AIDS-like syndrome--murine acquired immunodeficiency syndrome--in C57B1/6 mice and impairs spatial learning in the Morris water maze without gross motor impairment. We used a shuttle shock-avoidance procedure to examine the effects of LP-BM5 infection on learning and retention of avoidance behavior. Thirty mice were inoculated with LP-BM5; 30 received vehicle (DMEM) injections. Fifteen LP-BM5 and 15 DMEM mice were trained in avoidance 7 wk after inoculation; retention of the avoidance response was tested 4 wk later. The remaining mice were trained 11 wk after inoculation. In animals trained 7 wk after inoculation, the groups performed similarly, with a marginally significant tendency for LP-BM5-infected animals to make more avoidance responses. This group difference was significant when animals were retested at 11 wk. However, LP-BM5 animals trained 11 wk after inoculation made significantly fewer avoidance responses than controls trained at the same time. We conclude that in later stages of disease, LP-BM5 impairs response acquisition, but not performance, in the active avoidance procedure. Results extend the use of the LP-BM5-infected mouse as a model of AIDS dementia complex.

Animals↗

PubMed1997

Effects of some phenylethylamines in rhesus monkeys trained to discriminate (+)-amphetamine from saline.

Although the structure-activity relationships (SAR) for the discriminative stimulus (DS) effects of phenylethylamines (PEAs) have been extensively evaluated in rats, only isolated components of the SAR have been studied in other species. Since DS effects in animals predict subjective effects in humans, it is important to establish cross-species generality of substitution results. In the present experiment, rhesus monkeys (n = 4) were trained to discriminate (+)-amphetamine (0.56 or 1.0 mg/kg, i.g.) from saline in a two-lever drug discrimination paradigm. Responding was maintained under a fixed-ratio discrete-trials schedule of shock avoidance. (+)-Amphetamine, and the N-substituted phenylethylamines (+)-methylamphetamine, and (+)-ethylamphetamine all engendered dose-dependent, full substitution for (+)-amphetamine and had no effect on rate of responding. In contrast, the ring-substituted compounds (+/-)-4-methoxyamphetamine (PMA), (+/-)-2,5-dimethoxy-4-methylamphetamine (DMA), (+/-)-2,5-dimethoxy-4-methylamphetamine (DOM), and (+/-)-3,4, 5-trimethoxyamphetamine (TMA) occasioned little or no (+)-amphetamine-appropriate response up to doses of 3.0 or 10 mg/kg. Therefore, it appears that monkeys respond to N-substituted amphetamines in the same way as rats, at least qualitatively. Considering that ring-substituted compounds have been found to partially substitute for (+)-amphetamine in rats, it is possible that the (+)-amphetamine DS may be pharmacologically more selective in monkeys. However, methodological differences may also explain differences between experiments.

Amphetamine↗

PubMed1997

Choice between cocaine and food in a discrete-trials procedure in monkeys: a unit price analysis.

In behavioral economics, the unit price (UP) model of drug consumption defines UP as the ratio of the response requirement to the dose of drug. This model makes two predictions: increasing UP will decrease consumption, and consumption at a given UP will be constant regardless of the response requirement and dose that make up the UP. The present experiment was designed to test the UP model in rhesus monkeys allowed to choose between an IV injection of cocaine and food in a discrete-trials choice procedure. Both response requirement/injection and dose of cocaine were varied in such a way as to yield UPs from 40 to 10,000 responses per mg/kg. The response requirement for food was always 30 and there was a 30-min time-out between trials to allow the direct effects of cocaine on responding to dissipate. Consistent with the UP model, cocaine consumption decreased as UP increased. However, at a given UP, cocaine consumption was usually higher at the higher dose. Thus, under the conditions of the present experiment an important component of the UP model of drug consumption was not supported. It may be that UP is not a reliable predictor of consumption under conditions in which the direct effects of a drug on responding are minimized.

Animals↗

PubMed1997

Further analysis of choice between cocaine and food using the unit price model of behavioral economics.

Behavioral economics defines unit price (UP) as the ratio of the response requirement to magnitude of reinforcer. When applied to drug self-administration, the UP model defines UP as the ratio of the response requirement to the unit dose of drug. This model makes two predictions about drug self-administration: increasing UP decreases consumption and consumption at a given UP will be constant regardless of the response requirement and dose that make up the UP. In previous experiments conducted in rhesus monkeys allowed to choose between an i.v. injection of cocaine and food, the UP model has failed to adequately predict drug consumption in that consumption varied (increased with dose) at a given UP. However, previous experiments have allowed a fixed number of choice trials/day, thereby imposing a procedural ceiling on consumption that may have influenced conformity to the UP model. In the present experiment, the number of choice trials available was varied in such a way that constant drug consumption was possible over the range of UPs tested. The response requirement for cocaine was varied between 15 and 1200 lever presses/injection and the dose of cocaine was varied between 0.05 and 0.2 mg/kg/inj, yielding UPs from 300 to 5600 responses/mg/kg. The response requirement for food was always 30. As predicted by the UP model, cocaine consumption decreased as UP increased. Moreover, in contrast to previous experiments, consumption did not vary significantly across the response requirement/dose combinations that made up a UP. A detailed analysis suggested that a decrease in magnitude of the alternative reinforcer (one rather than three food pellets), rather than the increase in trials, was responsible for the improved conformity to the UP model in the present experiment relative to previous experiments. Taken together with previous experiments, the present experiment suggests that conformity to the UP model of drug consumption in a choice situation is dependent upon the magnitude of alternative reinforcers that are available. Consumption was best predicted by the UP model when the magnitude of the alternative reinforcer was small.

Animals↗

PubMed1997

Evidence-based management of upper respiratory infection in a family practice teaching clinic.

BACKGROUND AND OBJECTIVES: Management of upper respiratory infection (URI) was examined in a family practice clinic to determine evidence-based practices, specifically for medication choice. Scientific evidence supports the use of decongestants and perhaps decongestant/antihistamine combinations in adolescents and adults and antipyretics in all age groups. The use of cold preparations for children younger than age 5 is not evidence based. METHODS: Data on demographics, medications prescribed, and over-the-counter medications recommended were collected from patient charts for 293 URI visits over a 6-month period. The cost of evidence-based URI treatment was compared with the cost of nonevidence-based treatment. RESULTS: Thirty-three percent of patients younger than age 5 were given a prescription; 96% of the prescription cost in this age group was nonevidence based. Twenty-six percent of all patients seen were given unnecessary and potentially harmful medication. These unnecessary medications accounted for almost 60% of the total prescription cost. Various combinations of antihistamines, decongestants, and antitussives were most commonly prescribed. CONCLUSIONS: Few medications have been shown to effectively alleviate the symptoms of the generally self-limited, benign common cold. Medications are often overprescribed, escalating health care costs and, in some cases, exposing the patient to dangerous side effects. Family physicians and educators are encouraged to reexamine their treatment and teaching practices for the common cold.

Adolescent↗

PubMed1995

Unit-price analysis of opioid consumption by monkeys responding under a progressive-ratio schedule of drug injection.

Several reports have indicated that drug consumption in self-administration procedures is a function of the ratio of the instrumental requirement to the dose of drug, a quantity termed unit price. We evaluated three predictions from this unit-price model in a reanalysis of data on opioid self-administration in rhesus monkeys responding under a progressive-ratio schedule (Hoffmeister, 1979). We evaluated whether consumption was inversely related to unit price, and compared the goodness of fit of an equation devised by Hursh, Raslear, Shurtleff, Bauman, and Simmons (1988) to that of a linear model predicting consumption as a function of dose. We also tested whether consumption was constant when the same unit price was comprised of different combinations of dose and instrumental requirement. Consumption declined overall as unit price increased. The equation devised by Hursh et al. and the linear model based on dose fit the data equally well. Drug consumption was not uniform at a given unit price. The analyses suggest limits on the unit-price model as a characterization of drug consumption.

Animals↗

PubMed1994

John Blackall (1771-1860): failure to see the obvious in dropsical patients with coagulable urine?

Despite his success in publishing a book which was widely read and which drew attention to the fact that some cases of dropsy are associated with coagulable urine, John Blackall failed to make the link between this phenomenon and disease of the kidneys. Thus, to Richard Bright must go the credit for providing the critical understanding of the phenomenon. The single most probable reason for Bright's success and Blackall's failure was that Bright carried out post mortem examinations of almost all of his patients. In addition, Bright was ruthlessly systematic in documenting his autopsy findings, and not least was the fact that he possessed the rare talent of being objective in looking at his data, without being influenced by the preconceptions of the times.

Edema↗

PubMed1977