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Biomedical subjects

J R Hughes

Publications and source records attributed to J R Hughes.

At least 19 recordsLinked to original sources
PubMed1992

Optic neuropathy in Hodgkin's disease.

Hodgkin's disease is a rare cause of infiltrative optic neuropathy, which typically evolves late in the disease course. We managed an unusual case of isolated optic neuropathy in a 21-year-old man occurring during clinical remission from Hodgkin's disease. Radiotherapy and treatment with high-dose systemic corticosteroids resulted in dramatic improvement in vision. Even without other evidence of recurrent disease, acute-onset optic neuropathy in a patient with a history of a lymphoproliferative disorder should raise the question of a reemergence of the malignancy.

Adult↗
PubMed1992

Topographic analysis of visual evoked potentials from flash and pattern reversal stimuli: evidence for "travelling waves".

In this mapping study of the entire scalp area, the responses to flash (FL) and pattern reversal (PR) stimuli were studied in 34 normal subjects. The N70, P100, N135 and P180 were similar from both stimuli but with some differences in amplitude and latency, especially the variability of the latency of P100 from FL. A polarity inversion was usually seen for all components, especially at opposite ends of the scalp and a zero-potential was noted for all four components near Cz Pz. Evidence is seen that the frontal N100 is likely not the other end of a dipole involving the posterior P100. Lateral components as P120, N150 and N200 were also described. The major finding was evidence of "travelling" waves that appear to move in both the AP and PA directions throughout the scalp that eventually arrive on the posterior regions and appear as N70, P100, N135 and P180.

Adolescent↗
PubMed1992

Behavioral economics of drug self-administration. IV. The effects of response requirement on the consumption of and interaction between concurrently available coffee and cigarettes.

In behavioral economics, consumption of a reinforcer is determined by its price and by the price of other available reinforcers. This study examined the effects of price manipulations on the consumption of concurrently available coffee and cigarettes. During fifteen 4-h sessions, coffee and cigarettes were concurrently available according to fixed-ratio (FR) schedules of reinforcement. After consumption stabilized under a fixed ratio 100 for both reinforcers, the response requirement for each reinforcer was varied separately (i.e., FR 100, 1000 and 2500), while the response requirement for the other reinforcer was kept at 100. Increasing the FR value decreased coffee and cigarette consumption to a similar degree. Also, as the price for cigarettes increased (and consumption decreased), coffee consumption decreased; however, as the price of coffee increased, cigarette consumption did not change. These results indicate that for this setting the reinforcing effects of cigarettes and coffee were comparable but interacted asymmetrically. These findings when analyzed and quantified via economic concepts of own-price and cross-price elasticity illustrate the viability of using behavioral economics to examine drug self-administration in a choice paradigm.

Adolescent↗
PubMed1992

Behavioral economics of drug self-administration. III. A reanalysis of the nicotine regulation hypothesis.

The maintenance of a characteristic level of nicotine in a smoker's body is referred to as nicotine regulation. Considerable research has examined this question of whether smokers regulate nicotine intake. This is because nicotine regulation raises the question of whether smokers who, to decrease their intake of tar, switch to low tar/low nicotine cigarettes will increase the number and/or intensity of cigarettes smoked. Although the results of studies examining nicotine regulation are reported as generally consistent, considerable variability exists across these analyses such that the health hazards of smoking low tar/nicotine cigarettes remains uncertain. In the present analysis, these studies were analyzed to ascertain whether a behavioral-economic interpretation could better quantify the effects of changing nicotine yield on individuals' nicotine and smoke consumption. Specifically, 17 nicotine-regulation studies were reanalyzed using a unit-price analysis (i.e., cost-benefit analysis). The reanalysis showed less variability across regulation studies than previously reported; a positively-decelerating demand curve was found across most studies, consistent with previous unit-price analyses of food- and drug-maintained behavior. The benefits of this reanalysis versus the traditional regulation interpretation are that the behavioral economics approach: 1) brings unity to a variable set of data, 2) shows a nonlinear relationship, previously considered to be linear, between nicotine consumption and nicotine yield, 3) shows that nicotine yields higher, and not lower, than the smoker's usual brand decrease smoke consumption and thus decreases consumption of the harmful agents in tobacco, 4) better quantifies the data and provides a more parsimonious interpretation that generalizes to other drugs and food-maintained behavior in humans and nonhumans and, 5) integrates behavioral and pharmacological factors that control the consumption of reinforcers. These results suggest the value of behavioral economics in the study of consumptive behaviors and clinically suggest, in agreement with the studies contained herein, that decreasing the smoker's usual nicotine yield can have potential health risks for smokers who are unable to stop smoking.

Behavior↗
PubMed1992

Forced-choice versus free-choice procedures: caffeine self-administration in humans.

Methodological comparisons of procedures for drug self-administration are rare. In studies examining the reinforcing effect of caffeine in humans, caffeine self-administration usually has been inferred from performance under forced-choice procedures. In the present experiment, caffeine self-administration via coffee was compared under forced-choice and free-choice conditions; i.e., when subjects were and were not required to use a minimum number of coffees. Ten moderate coffee drinkers (2-7 cups/day) were assigned to forced- and free-choice conditions using a randomized cross-over design. Under each choice condition, subjects completed six independent, double-blind trials, consisting of a 2-day exposure period followed by a 2-day test period. During exposure, subjects consumed either decaffeinated or caffeinated (100 mg/serving) coffee on day 1 and the other coffee on day 2. During the test period, subjects had concurrent access to the same decaffeinated and caffeinated coffees. Under the forced-choice condition, subjects were required to drink at least four cups of coffee per day during the test period. Under the free-choice condition, subjects did not have a minimum-cup requirement. In general, the relative rate at which subjects self-administered caffeinated versus decaffeinated coffee was similar across choice conditions, even though subjects self-administered significantly fewer cups of both coffee types under the free-choice than the forced-choice condition. These results suggest that, at least for caffeine, forced-choice and free-choice procedures produce comparable results. Whether this finding generalizes to a context in which caffeine or another drug is more robustly self-administered, remains to be determined.

Adult↗
PubMed1992

Triazolam as a discriminative stimulus in humans.

Seven healthy normal male and female volunteers (19-42 years) were trained to discriminate between the benzodiazepine triazolam (0.32 mg/70 kg; e.g. drug A) and placebo (e.g. drug B). During the first four daily sessions, drug A and drug B were administered orally in capsules 60 min prior to the session on alternate days and subjects were informed of the drug label at the time of drug administration. Subsequently, drug A and drug B were administered in a randomized-block fashion and subjects identified the drug code they thought they received. Subjects were informed of the drug code post-session. Once the criterion for discrimination was met (i.e. correct drug code identification on four consecutive sessions), the dose-effect curve for triazolam (0.1-0.75 mg/70 kg) was determined. The discrimination was acquired in all subjects; triazolam (0.32 mg/70 kg) and placebo produced approximately 85-95% correct responding. During the dose-effect curve determination, triazolam produced dose-related increases in triazolam-appropriate responding and self-reported sedation and drug strength. These results indicate that a triazolam-placebo discrimination can be acquired and that the triazolam discriminative stimulus effect is related to dose and to self-reported sedation.

Adult↗
PubMed1992

The scientific/clinical response to the cocaine epidemic: a MEDLINE search of the literature.

Index Medicus (1966-1990) was searched to quantify and characterize the scientific/clinical community's responses to the cocaine epidemic. The rate of growth in the cocaine literature was compared with the rate of growth in the heroin and marijuana literatures in the 1960s and 1970s. Articles on cocaine increased dramatically over the past 7 years suggesting a clear response from the scientific/clinical community to the public health problems presented by the cocaine epidemic. That literature spans a wide range of areas addressing many scientific and health-care issues. This increase in cocaine citations is similar to that which occurred previously in response to use of heroin and marijuana.

Cocaine↗
PubMed1992

Observer reports of smoking status: a replication.

Observer and self-reports of abstinence from smoking were compared at 2-, 7-, 14-, 30-, 90-, and 180-day follow-ups and with biochemical verification at 180-day follow-up in a study of 630 self-quitters. Observer reports were often not returned (25-65%), rarely refuted self-reported abstinence (< 1%), and were often discordant with biochemical results (32%). These results replicate a prior finding (Hughes, 1990) that observer verification of smoking status during a prospective study of cessation is not very helpful.

Adult↗
PubMed1992

Tobacco withdrawal in self-quitters.

Self-reported and observer-rated signs and symptoms of nicotine withdrawal were assessed precessation and 2, 7, 14, 30, 90, and 180 days postcessation in smokers who quit on their own for 30 days. Anxiety, difficulty concentrating, hunger, irritability, restlessness, and weight gain increased, and heart rate decreased, postcessation (p less than .001). Except for hunger and weight gain, these symptoms returned to precessation levels by 30 days postcessation. Craving, depression, and alcohol or caffeine intake did not reliably increase. Postcessation depression, but not withdrawal symptoms, craving, or weight gain, predicted relapse. These results are consistent with prior studies.

Adult↗
PubMed1992

Smoking cessation among self-quitters.

We examined cessation among 630 smokers who quit abruptly on their own. Continuous, complete abstinence rates were 33% at 2 days, 24% at 7 days, 22% at 14 days, 19% at 1 month, 11% at 3 months, 8% at 6 months postcessation, and 3% at 6 months with biochemical verification. Slipping (smoking an average of less than 1 cigarette/day) was common (9% to 15% of subjects) and was a strong predictor of relapse; however, 23% of long-term abstainers slipped at some point. These results challenge beliefs that most smokers can initially stop smoking and that most relapse occurs later on postcessation.

Adult↗
PubMed1992

Should caffeine abuse, dependence, or withdrawal be added to DSM-IV and ICD-10?

OBJECTIVE: The authors reviewed basic science and clinical data on caffeine abuse, dependence, and withdrawal in order to make a conclusion about whether these disorders exist and should be included in DSM-IV and ICD-10. METHOD: Studies were located through computerized searches, reference sections of published articles, and written requests. RESULTS: The studies show that abstinence from caffeine induces a withdrawal syndrome of headache, fatigue, and drowsiness which begins within 12-24 hours and lasts about 1 week. The syndrome can be severe and appears to be one reason for continued use of coffee. The prevalence of this caffeine withdrawal syndrome is unknown. Use of caffeine may aggravate some common behavioral and medical disorders. In double-blind tests, a subset of coffee and soda drinkers reliably self-administered caffeinated beverages in preference to uncaffeinated beverages. Clinical indicators of dependence, such as difficulty stopping use of caffeine and use despite harm, have not been documented. CONCLUSIONS: Caffeine withdrawal but not caffeine abuse or dependence should be included as a diagnosis in DSM-IV and ICD-10. Future research should focus on whether some caffeine users exhibit clinical indicators of drug dependence.

Caffeine↗
PubMed1992

Changes in reactivity during the 6/second spike and wave complex.

This study on a patient with the WHAM form of the 6/sec spike and wave complex shows significant delays in reaction time and increased variability when stimuli were presented during the complex and within 1 second after it, especially when the pattern was high in amplitude and short in duration, and also during theta bursts without the spike component. The similarities and differences between this pattern and the 3/sec spike and wave complex are discussed.

Acoustic Stimulation↗
PubMed1992

The Lennox-Gastaut syndrome: electroencephalographic characteristics, clinical correlates, and follow-up studies.

Electroencephalographic and clinical findings are reported for 100 patients with the Lennox-Gastaut (LGS) triad of slow bilateral spike and wave (BSW), retardation and multiple seizures. Neurological and mental deficits were frequently observed, especially in patients who developed seizures before age 1 yr. More than half of the patients had focal epileptiform discharges that peaked in occurrence at age 4-6 yrs. EEG follow-up showed that background frequency slowed when patients developed the LGS pattern, and increased after recovery. Only 2 patients developed normal EEGs on follow-up, although 22 patients no longer showed the LGS pattern after an average of 3 yrs 3 mos follow-up.

Adolescent↗
PubMed1992

Effects of cocaine and alcohol, alone and in combination, on human learning and performance.

The acute effects of cocaine hydrochloride (4 to 96 mg/70 kg) and alcohol (0 to 1.0 g/kg), administered alone and in combination, were assessed in two experiments with human volunteers responding under a multiple schedule of repeated acquisition and performance of response chains. Subjects were intermittent users of cocaine and regular drinkers who were not cocaine or alcohol dependent. Alcohol was mixed with orange juice and ingested in six drinks within 30 min; cocaine was administered intranasally 45 min after completion of drinking. In each component of the multiple schedule, subjects completed response sequences using three keys of a numeric keypad. In the acquisition component, a new sequence was learned each session. In the performance component, the response sequence always remained the same. Results were consistent in both experiments, despite variations in the order in which the drugs were tested alone and in combination. Alcohol administered alone increased overall percentage of errors and decreased rates of responding in the acquisition component, whereas responding in the performance component generally was unaffected. Cocaine administered alone decreased rates of responding but did not affect accuracy of responding in the acquisition component, and enhanced accuracy of responding without affecting rates of responding in the performance component. The combined doses of cocaine and alcohol attenuated the effects observed with alcohol and cocaine alone. These results suggest that, under the conditions investigated in this study, (a) alcohol produces greater behavioral disruption than cocaine or cocaine-alcohol combinations, (b) cocaine and alcohol each attenuate effects of the other, and (c) such attenuation is most pronounced for cocaine attenuating the disruptive effects of alcohol.

Adult↗
PubMed1992

Caffeine drug discrimination in humans: acquisition, specificity and correlation with self-reports.

This study evaluated the discriminative stimulus effects of caffeine in humans. Nine normal male and female volunteers (ages 18-28) were trained to discriminate between the methylxanthine central nervous system stimulant caffeine (320 mg/70 kg, p.o.) and placebo. Monetary reinforcers were earned for identifying correctly the letter code associated with each substance. After four training sessions, the ability to discriminate between the two training conditions was tested for 20 sessions (test-of-acquisition). In subjects who met the criterion for discrimination (i.e., greater than or equal to 85% correct responding on greater than or equal to 4 consecutive sessions during the last 10 test-of-acquisition sessions) dose-effect curves for caffeine (0, 56, 100, 180, 240 and 320 mg/70 kg) and for the benzodiazepine triazolam (0, 0.10, 0.32 and 0.56 mg/70 kg) were determined. Seven of the nine subjects learned the caffeine-placebo discrimination and their performance improved across the 20 test-of-acquisition sessions. The training dose of caffeine (320 mg/70 kg) produced stimulant-like self-reports that differed from placebo when the letter codes were identified correctly, but not when the letter codes were identified incorrectly. Novel caffeine doses produced dose-related increases in caffeine-appropriate responding (N = 4), whereas triazolam produced predominantly placebo-appropriate responding (N = 3) and self-reports that differed from both caffeine and placebo. Throughout dose-effect curve determinations, the training dose of caffeine and placebo continued to be identified correctly (range: 84-100% correct responding). These results suggest that a caffeine (320 mg/70 kg)-placebo discrimination 1) can be acquired and maintained, 2) is related to self-reported drug effects if the training conditions are correctly identified and 3) has some pharmacological specificity.

Adult↗