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Biomedical subjects

J Handel

Publications and source records attributed to J Handel.

16 recordsLinked to original sources
PubMed2004

The effects of moclobemide on autonomic and cognitive functions in healthy volunteers.

BACKGROUND: Moclobemide, a reversible and selective inhibitor of the MAO-A isoenzyme, is marketed as an antidepressant that lacks autonomic and cognitive side effects. However, only few and inconclusive quantitative data on the effects of moclobemide on autonomic and cognitive functions have been reported in the literature. Therefore, a double-blind, randomized, placebo-controlled crossover trial was performed. METHODS: Twelve healthy male volunteers (age 22-29 years) received orally 150 mg moclobemide b.i.d. and placebo for 14 days each. Heart rate variability (HRV) and skin conductance response (SCR) following sudden deep breath were employed as parameters for autonomic function. Quantitative EEG (qEEG) and psychometric tests served as parameters for cognitive function. Measurements were performed before the start of drug administration and repeatedly on the last treatment day. RESULTS: Parameters of HRV and SCR were not changed by multiple dosing with moclobemide (P > 0.05). Neither cognitive functions such as flicker fusion frequency, memory, choice reaction time, and psychomotor performance nor qEEG was significantly influenced, but subjective tiredness was decreased at all time points of measurement after multiple dosing with moclobemide (P < 0.05). CONCLUSIONS: In conclusion, moclobemide does not appear to influence autonomic functions or cognitive functions when given subchronically to healthy humans. In contrast, changes in subjective mood hint at a subtle activating effect.

Adult↗
PubMed1997

Effect of hyperventilation on regional cerebral blood flow in head-injured children.

OBJECTIVES: To study cerebral blood flow and cerebral oxygen consumption in severe head-injured children and also to assess the effect of hyperventilation on regional cerebral blood flow. DESIGN: Prospective cohort study. SETTING: Pediatric intensive care unit at a tertiary-level university children's hospital. PATIENTS: Twenty-three children with isolated severe brain injury, whose admission Glasgow Coma Scores were <8. INTERVENTIONS: PaCO2 was adjusted by altering minute ventilation. Cerebral metabolic measurements were made at three levels of PaCO2 (>35, 25 to 35, and <25 torr [>4.7, 3.3 to 4.7, and <3.3 kPa]) after allowing 15 mins for equilibrium. MEASUREMENTS AND MAIN RESULTS: Thirty-eight studies (each study consisting of three sets of measurements at different levels of PaCO2) were performed on 23 patients. At each level of PaCO2, the following measurements were made: xenon-enhanced computed tomography scans; cerebral blood flow; intracranial pressure; jugular venous bulb oxygen saturation; mean arterial pressure; and arterial oxygen saturation. Derived variables included: cerebral oxygen consumption; cerebral perfusion pressure; and oxygen extraction ratio. Cerebral blood flow decreased below normal after head injury (mean 49.6 +/- 14.6 mL/min/100 g). Cerebral oxygen consumption decreased out of proportion to the decrease in cerebral blood flow; cerebral oxygen consumption was only a third of the normal range (mean 1.02 +/- 0.59 mL/min/100 g). Neither cerebral blood flow nor cerebral oxygen consumption showed any relationship to time after injury, Glasgow Coma Score at the time of presentation, or intracranial pressure. The frequency of one or more regions of ischemia (defined as cerebral blood flow of <18 mL/min/100 g) was 28.9% during normocapnia. This value increased to 73.1% for PaCO2 at <25 torr. CONCLUSIONS: Severe head injury in children produced a modest decrease in cerebral blood flow but a much larger decrease in cerebral oxygen consumption. Absolute hyperemia was uncommon at any time, but measured cerebral blood flow rates were still above the metabolic requirements of most children. The clear relationship between the frequency of cerebral ischemia and hypocarbia, combined with the rarity of hyperemia, suggests that hyperventilation should be used with caution and monitored carefully in children with severe head injuries.

Adolescent↗
PubMed1992

Smoking reduction during pregnancy by a program of self-help and clinical support.

This study investigated the impact of a low-cost, pregnancy-specific self-help smoking-cessation program on patient smoking behavior both pre- and postpartum. The population consisted of 274 English-speaking women enrolled in a large health maintenance organization who reported smoking at the time of the baseline survey or had quit within the previous 3 months. A control group receiving standard obstetric care was compared with two experimental groups, one receiving the self-help materials and standard care and the other receiving the materials plus brief regular clinician interactions and counseling about smoking. Smoking data were obtained from two additional self-reported surveys conducted at 6 months' gestation and approximately 8 weeks postpartum. Self-reported smoking behavior was verified using a urine cotinine test, which revealed no significant differences between the groups. Among baseline smokers, although neither intervention yielded significantly higher 6-month nonsmoking rates compared with controls, both interventions significantly increased the proportion of women who were not smoking postpartum. Among those who had quit smoking at baseline, only the more intensive intervention significantly increased maintenance of non-smoking postpartum. Brief counseling, a simple charting system, and improved access to educational materials allowed the program to be integrated easily into routine prenatal care at a cost of $50-111 per patient.

Adolescent↗
PubMed1991

Thromboembolic events in a severely burned patient.

A patient with severe burns suffered spontaneous bilateral peripheral arterial thromboses which were successfully treated with recombinant human tissue plasminogen activator (rt PA) (Actilyse). The patient later died from complications of burns.

Adult↗
PubMed1990

Time course of vitamin E repletion in the premature infant.

Plasma and erythrocyte (RBC) tocopherol-isomer concentrations were determined serially in forty-two premature infants (25-35 weeks gestation) from birth to 8 weeks of age. For comparison purposes vitamin E status was also determined in six term infants over the first 8 d following birth and in a group of thirteen adult volunteers. Vitamin E intakes in term and preterm infants were calculated from recorded food intakes and blood transfusions. In term infants plasma vitamin E concentration rose from 1.9 mg/l (day 1) to 8.2 mg/l by day 8. In comparison preterm plasma vitamin E concentration, 0.3 mg/l (day 1), did not change appreciably by day 8 (0.7 mg/l). Likewise RBC vitamin E concentration increased in term infants from 1.3 mg/l (day 1) to 2.7 mg/l (day 8), while in preterm infants it remained unchanged, 1.5 mg/1 (day 1) v. 1.3 mg/l (day 8). Over the 3 weeks following birth, RBC vitamin E concentrations in the premature infants increased to adult values, while plasma vitamin E concentration did not reach the adult range until 8 weeks post-term. These slow changes in plasma vitamin E status occurred even though the vitamin E intake of these infants was similar to that proving adequate for term infants.

Adult↗
PubMed1988

Lack of effect of nitrendipine on the pharmacokinetics and pharmacodynamics of midazolam during steady state.

1. The possible interaction (as indicated by rat experiments) between calcium channel blocking agents and benzodiazepines has been evaluated in nine healthy subjects. 2. Subsequently to an intravenous loading dose (0.07 mg kg-1) midazolam was infused for 6 h (0.035 mg kg-1 h-1) and steady state plasma levels between 54 to 114 micrograms l-1 were achieved. Two hours after the bolus of midazolam a solution of 20 mg nitrendipine or placebo was administered in a randomized, double-blind crossover fashion. 3. The marked sedative-hypnotic effects of midazolam as assessed by visual analogue scales (about four fold increase in the sedation index) and choice reaction time (100% prolongation) indicated some form of adaptation or tolerance towards the end of the infusion. However, the midazolam-induced impairments were not affected by nitrendipine. 4. EEG-data indicated stabile benzodiazepine-like effects during the complete infusion period of midazolam (e.g. decrease in alpha activity, increase in sigma, delta 2 and beta 1 activity). Again, these alterations were not modified by nitrendipine. 5. There was also no pharmacokinetic interaction between both agents, since elimination of midazolam (t 1/2 = 2.5 +/- 0.8 h; CL = 548 +/- 143 ml min-1) was in close agreement with control values (t 1/2 = 2.4 +/- 0.6 h; CL = 512 +/- 102 ml min-1). Likewise, plasma levels of nitrendipine were comparable to literature data. 6. Thus, it could be concluded that nitrendipine does not affect the action of midazolam and therefore a direct involvement of calcium at the benzodiazepine receptor site is unlikely under our clinical conditions.

Adult↗
PubMedDate not supplied

Tricyclic antidepressants: effects on extinction and fear learning.

Rats trained to run an alley for a food reward were extinguished following injections of different antidepressants. When retested several days later, the animals extinguished following pretreatment with the NE reuptake blocker protriptyline showed faster running speeds than did the other groups. Other rats given electrical shocks following pretreatment with protriptyline avoided the compartment in which they had been shocked less than did animals shocked following pretreatment with other antidepressants. This implies an interferance with some aspect of the learning or consolidation process which is correlated with the degree of NE reuptake blockage. It is hypothesized that NE terminals are deactivated following frustrative nonreward or punishment by the conversion and reuptake of the released NE to an altered extinction molecule.

Animals↗