Biomedical subjects

M M Ghoneim

Publications and source records attributed to M M Ghoneim.

At least 73 records · Page 4Linked to original sources

PubMed1988

Nitrous oxide and human state-dependent memory.

State-dependent effects of nitrous oxide on human memory were examined by administering serial and paired-associate learning tasks to subjects receiving 20 and 30% nitrous oxide or placebo. Nitrous oxide in 30% concentration impaired learning of both tasks. In addition, it produced an atypical form of asymmetric state-dependent memory; subjects who learned while receiving placebo and recalled while receiving nitrous oxide displayed the worst recall.

Adult↗

PubMed1988

Comparison of psychologic and cognitive functions after general or regional anesthesia.

The behavior of 105 patients randomly assigned to receive either general or regional anesthesia and who underwent one of three types of surgery (hysterectomy, prostatectomy, or joint replacement) was assessed before, immediately after, and 3 mo after surgery. Psychologic status was assessed by the Sickness Impact Profile, the SCL-90-R, and a Metamemory Questionnaire. Cognitive functioning was measured by a battery of ten psychomotor, memory, and skilled performance tasks. Physical health was scored by the ASA classification of physical status, a health index, postoperative complications ratings, and a self-rated measure of the patient's health. There were cognitive differences across surgery groups due to age and gender variability among the patients; however, the type of anesthesia produced no difference in behavior. Both the physical and mental health indices showed improvement from the preoperative to the postoperative periods. General anesthesia appears to pose no risk to mental function and recovery beyond that associated with regional anesthesia and surgery.

Adult↗

PubMed1987

Diazepam, behavior, and aging: increased sensitivity or lower baseline performance?

Cognitive performance, psychomotor skills, and subjective reactions to diazepam and placebo were compared in 12 healthy, well-educated subjects in three age groups: 19-28, 40-45, and 61-73 years old. With only minor exceptions, the changes in performance caused by diazepam and age differences were statistically additive and noninteracting. Diazepam did not act synergistically in older individuals; the decrements in performance were about the same in all age groups. Baseline performance decreased with increasing age; middle-aged subjects performed more like older than younger subjects. A variety of tasks exhibited similar effects of aging and diazepam, i.e., when performance declined with increasing age, it was also reduced by diazepam.

Adult↗

PubMed1987

Effects of a subanesthetic concentration of nitrous oxide on establishment, elicitation, and semantic and phonemic generalization of classically conditioned skin conductance responses.

Classical conditioning of skin conductance responses was studied in 16 men and 16 women breathing 30% nitrous oxide or 100% oxygen to see how nitrous oxide affected establishment, elicitation, and generalization of conditioned responses (CRs). For CRs that had been established before gas inhalation, nitrous oxide blocked elicitation of "anticipatory" (long latency) but not "orienting" (short latency) CRs. Nitrous oxide appeared to prevent new CRs from being established during its inhalation, but learning evidently took place since anticipatory CRs could be elicited after nitrous oxide inhalation had ceased. Words were used as the conditioned stimuli and nitrous oxide altered generalization of CRs to other words related in meaning or sound, though generalization effects were limited. Nitrous oxide also seemed to reduce the efficacy of the unconditioned stimulus. The results were interpreted in terms of Rescorla's theory of classical conditioning.

Adult↗

PubMed1987

Diazepam and memory: evidence for spared memory function.

The effects of diazepam on several tests of memory were investigated in a double-blind study of 24 healthy young adults. Following a single oral administration of 0.3 mg/kg diazepam or placebo, subjects in the diazepam group showed marked impairment in immediate free recall of words as compared to placebo control subjects. However, diazepam-treated subjects demonstrated performance benefits from prior exposure to the same words on tests of memory priming using word completion and category-generation tasks. The two types of memory tests differ in their demand for conscious recollection. Tests of free recall have explicit (declarative) memory demands whereas the priming test places only implicit (procedural) demands upon memory. The results demonstrate that diazepam spares some forms of memory as does amnesia induced by neurological impairment.

Adolescent↗

PubMed1986

The behavioral actions of diazepam and oxazepam are similar.

In a double-blind and randomized study, we assessed the comparative pharmacodynamic profiles and behavioral effects of diazepam and oxazepam administered to young healthy volunteers. Diazepam 0.3 mg/kg or oxazepam 1.2 mg/kg or placebo were each administered orally to 13 subjects who were tested with tasks which measured learning and memory, cognition, psychomotor performance and mood before and for 9 h after treatment. The two drugs had similar actions, although subjective effects were milder after oxazepam, which also had a slower onset of action. There was no evidence of rebound behavioral impairment.

Adolescent↗

PubMed1986

Comparison of two benzodiazepines with differing accumulation: behavioral changes during and after 3 weeks of dosing.

The effects of diazepam (0.2 mg/kg for 15 days followed by 0.3 mg/kg for 7 days), oxazepam (0.8 mg/kg for 15 days followed by 1.2 mg/kg for 7 days), and placebo were studied in healthy subjects after the first dose, once a week during chronic dosing, and at 48 and 96 hours after withdrawal through a battery of psychologic tests. Diazepam produced quick effects followed by relatively rapid recovery, whereas the effects of oxazepam appeared slowly and lasted longer. Tolerance developed to the effects of both active drugs, so that when the dosages were increased, effects did not. There were no symptoms or signs indicative of withdrawal reactions. There were also no differences between the effects of the two active drugs after repeated dosing, although diazepam is an accumulating drug with active metabolites and oxazepam is a slightly accumulating one with inactive metabolites.

Administration, Oral↗

PubMed1986

Pharmacokinetic and pharmacodynamic interactions between caffeine and diazepam.

The pharmacokinetic and dynamic interactions of caffeine and diazepam after single doses were investigated in six young healthy adults. Subjects received 6 mg/kg of caffeine, 0.3 mg/kg of diazepam, and their combination at 2-week intervals according to a Latin square design and a double-blind procedure. Subjects had blood samples withdrawn at 0, 5, 10, 20, 30, 45, 60 minutes and every 30 minutes thereafter until 210 minutes after treatment. A battery of behavioral tests were administered before treatment and after each blood sampling, starting with the 20-minute period. The coadministration of caffeine with diazepam resulted in a 22% reduction in diazepam plasma levels. Caffeine produced hand tremors and diazepam produced sedation and impaired memory and cognition. The two drugs did not antagonize the effects of each other except in the symbol cancellation task. There were significant correlations between the caffeine and diazepam plasma levels and performance on several tasks and evidence for the development of acute tolerance to both drugs.

Adolescent↗

PubMed1985

Caffeine and diazepam: separate and combined effects on mood, memory, and psychomotor performance.

The effects of caffeine and diazepam on several mood, cognitive, learning, memory, and psychomotor tasks were investigated in a double-blind study of 108 young healthy adults who were randomly assigned to nine treatments; oral administration of caffeine (0, 3 and 6 mg/kg), diazepam (0, 0.15, and 0.30 mg/kg) and their combinations. Subjects completed a battery of tasks once before and twice after administration of the drugs. Caffeine alone showed no effects on cognitive, learning, and memory performance, but impaired fine motor coordination and increased anxiety and tenseness. Diazepam alone produced sedation, lowered other ratings of subjective moods, and impaired cognitive, learning, and memory performance. The two drugs did not antagonize the effects of each other, except in the symbol cancellation task.

Adolescent↗

PubMed1985

The pharmacokinetics of methohexital in young and elderly subjects.

The pharmacokinetics of methohexital were investigated in ten young adult volunteers and in seven young and seven elderly patients. The latter two groups underwent enflurane and nitrous oxide anesthesia and surgery. Each subject received a bolus dose of 2 mg/kg of methohexital intravenously. Plasma levels of the drug were measured for 8 h after injection by gas chromatography using a nitrogen detector. Anesthesia (combined with surgery) and increase in age did not separately affect the kinetics of the drug; however, the elimination half-life was longer in the elderly patients group than in the young non-anesthetized volunteers.

Adult↗

PubMed1985

Etomidate anesthesia inhibits the cortisol response to surgical stress.

Plasma cortisol was measured in 18 patients undergoing gynecological procedures under etomidate or methohexital and nitrous oxide anesthesia. Plasma ACTH was also measured in three patients in each group. The mean plasma cortisol concentration before anesthesia was comparable in both groups. Plasma cortisol increased in patients anesthetized with methohexital, while none of the patients anesthetized with etomidate had an increase in plasma cortisol. The increase in plasma ACTH was equivalent in the two groups. Therefore, etomidate is a potent inhibitor of the adrenal response to surgery. The absence of clinical consequences associated with the blunted response suggests that a major increase in adrenal hormone production may not be necessary during surgery.

Adrenal Cortex↗

PubMed1985

Ketamine: behavioral effects of subanesthetic doses.

Effects of subanesthetic doses of ketamine (0.25 and 0.5 mg/kg) on memory, cognition, psychomotor function, subjective moods, and incidence of adverse reactions were investigated in 34 healthy young volunteers. The drug caused impairment of immediate and delayed recall. Most of the impairment was due to interference with retrieval processes. Recovery was virtually complete 60 minutes after administration. The incidence of adverse reactions was high. Benzodiazepines need to be administered even when ketamine is used in subanesthetic doses.

Adolescent↗

PubMed1984

Diazepam and propranolol in panic disorder and agoraphobia.

The response to diazepam and propranolol hydrochloride was compared in 21 patients who (with one exception) met DSM-III criteria for panic disorder and agoraphobia. Each drug was administered for two weeks in double-blind fashion according to a crossover design. The response to diazepam was significantly superior on all measures. By observer rating, 18 patients showed at least moderate improvement with diazepam compared with seven receiving propranolol. Panic attacks and phobic symptoms responded to diazepam, but not to propranolol. The results suggest that benzodiazepines constitute effective short-term treatment for these newly defined disorders.

Adult↗

PubMed1984

Diazepam and memory: retrograde facilitation produced by interference reduction.

Although diazepam (Valium) reduces learning and memory of information presented after administration (anterograde amnesia), in some cases it improves retention of predrug information (retrograde facilitation). Three experiments examined the magnitude and the conditions for producing retrograde facilitation and tested three hypotheses about the cause of memory enhancement. Differential effort and enhanced consolidation explanations were rejected in favor of a reduced interference interpretation. Improvement in predrug memory occurs because poor postdrug learning reduces the amount of new information available to interfere with prior learning.

Adolescent↗

PubMed1984

Dose-response analysis of the behavioral effects of diazepam: I. Learning and memory.

A total of 120 healthy volunteers were randomly assigned to four treatments (placebo, 0.1, 0.2, and 0.3 mg/kg) and three testing times (7 AM, 1 PM and 7 PM). Immediate and delayed free recall of word lists revealed consistent decreases in performance as oral diazepam dose increased from 0.1, 0.2, to 0.3 mg/kg. Paradoxically, as the dose increased, the number of predrug list words recalled also increased. A serial number-learning task displayed a pattern of delayed improvement of acquisition as the dose increased. Response times in a semantic-categories task were prolonged as the dose increased. Parallel recovery functions were observed for all doses and tasks. Full recovery after a single administration of 0.1, 0.2, and 0.3 mg/kg doses was estimated to occur after 3.5, 4.5, and 5.5 h, respectively. Several analyses were consistent with the view that acquisition and not retrieval was impaired by diazepam. There were no circadian interactions with the effects of the drug.

Adolescent↗

PubMed1984

Dose-response analysis of the behavioral effects of diazepam: II. Psychomotor performance, cognition and mood.

The psychomotor, cognitive, and mood effects of orally administered diazepam and placebo were measured over approximately equal to 3.5 h. A total of 120 volunteers were assigned to 12 groups of 10 each, representing the combination of four treatments (placebo, 0.1, 0.2, and 0.3 mg/kg diazepam) and three testing sessions (7 AM, 1 PM, and 7 PM). A variety of cognitive tasks, tapping and postural stability tests, and a mood evaluation scale were used. Psychomotor and cognitive functions showed consistent dose-response effects, while for subjective evaluations, the only effect of dose level was in the duration of sedation. The pattern of impairment of cognitive functions suggests that the drug affects speed rather than accuracy, and it primarily blocks acquisition of new information or skills. Use of repeated testing may therefore be necessary to detect subtle drug effects. Subjects reported no tranquilization , which suggests that the anxiolytic action of the drug cannot be studied in healthy volunteers. There was no circadian influence on the actions of the drug.

Adolescent↗

PubMed1984

Behavioral effects of oral versus intravenous administration of diazepam.

The behavioral effects of oral versus intravenous administration of diazepam were studied in 50 volunteers using a battery of memory, cognitive, mood and psychomotor tests repeated over a 4.5 hr period. Subjects received diazepam 0.2 mg/kg or placebo as capsules, commercial tablets or intravenous solution in a randomized double blind manner. While a quick onset of effects occurred with intravenous administration followed by the capsule and tablet oral administrations in that order, the recovery rate was similar for the 3 methods of administration. Contrary to many claims in the literature the effects of oral administration were substantial. Behavioral impairment was directly related to the magnitude of the memory component of the task. On many of the tasks the pattern of diazepam impairment was one of delayed improvement of performance, a pattern which would only be apparent with repeated testing. Subjects who received diazepam showed a paradoxical enhancement of recall for material learned before the drug.

Administration, Oral↗

PubMed1984

Ventilatory and mental effects of alfentanil and fentanyl.

Forty healthy, young volunteers received intravenously, in a double-blind and random fashion, 7.5 or 15 micrograms/kg of alfentanil, 1.5 or 3 micrograms/kg of fentanyl, or saline. The ventilatory response to CO2 was measured before and at 4, 20, 30, 50, 80, and 120 min post-treatment. Mental and psychomotor functions were measured before and at 10, 40, 100, 130, and 180 min post-treatment. Low and high-dose fentanyl caused significant respiratory depression up to 30 and 80 min post-treatment, respectively, while there was no depression with low-dose alfentanil and only at 4 min with high-dose alfentanil. The fentanyl to alfentanil potency ratio for respiratory depression was 13:1. High-dose fentanyl caused more intense and prolonged mental effects than other treatments. Neither drug affected learning or recall, although high-dose fentanyl impaired motor activity. Nausea and vomiting rates were similar between high-dose alfentanil and low-dose fentanyl.

Adult↗