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Biomedical subjects

R Byck

Publications and source records attributed to R Byck.

At least 19 recordsLinked to original sources
PubMed1997

Decreased digital flow persists after the abatement of cocaine-induced hemodynamic stimulation.

This study determined whether the development of delayed ischemic sequelae due to cocaine use--after the return of arterial blood pressure (BP) and heart rate to near-baseline values--may be attributable to regional vasoconstriction which persists beyond the acute systemic hemodynamic response. Five cocaine-using volunteers received intravenous infusions of saline placebo and cocaine 0.50 mg/kg several days apart in a double-blinded cross-over design. The intensity and duration of the cocaine-induced decrease in peripheral blood flow (as documented by laser Doppler flowmetry of the finger) were compared to the increases in BP (obtained with a Dinamap) and heart rate using paired t-test and repeated-measures analysis of variance. A significant increase in BP and a significant decrease in finger flow were noted by the first time point (5 min). Within 15 min, cocaine induced a 36% +/- 5% increase in BP and a 73% +/- 18% decline in finger flow (P < 0.05 for difference between percent change in BP and percent change in flow). Dinamap(systolic) and Dinamap(diastolic) returned to within 15% of baseline within 30 min, while finger flow remained more than 50% below baseline for the remainder of the 60-min study period (P < 0.05). Changes in heart rate paralleled those in BP. Except for isolated cases of documented coronary vasoconstriction in patients presenting with complications after cocaine use, this study is the first to document the persistence of cocaine-induced vasoconstriction of a sensitive vascular bed beyond the hypertensive response. It thus helps to explain the development of ischemic injury after cocaine use despite a stable rate-pressure product.

Adult↗
PubMed1992

Intravenous cocaine challenges during desipramine maintenance.

Intravenous challenges with placebo and cocaine doses ranging from 0.125 to 0.5 mg/kg were administered to five subjects using a within subjects design during placebo and active desipramine (DMI) maintenance at a fixed dose of 150 mg daily for at least 10 days. The "high" reported after cocaine infusion was not altered by DMI, but "desire for cocaine" after a single dose was attenuated. Together with the results of clinical trials of DMI for cocaine abuse, these laboratory results suggest that DMI may reduce cocaine craving both during and between cocaine binges. Physiologically, baseline heart rate was higher on DMI, but the incremental heart rate response to cocaine was attenuated.

Adult↗
PubMed1992

Read my lips.

The leading hairy edge of the lip is claimed to be related to peptic ulcer disease. Implications of this relationship are examined in light of psychiatric and probabilistic possibilities.

Hair↗
PubMed1989

Desipramine facilitation of initial cocaine abstinence.

We conducted a double-blind, random assignment, six-week comparison of desipramine hydrochloride (n = 24), lithium carbonate (n = 24), and placebo (n = 24) treatments for cocaine dependence. Subjects were 72 outpatient cocaine abusers who met DSM-III-R dependence criteria for cocaine but not for other substance abuse. Subjects in each treatment group were similar in history of cocaine and other substance abuse, cocaine craving, sociodemographics, and other psychiatric comorbidity. Desipramine, compared with both other treatments, substantially decreased cocaine use. Lithium treatment outcome did not differ from that of placebo. Desipramine-treated subjects attained contiguous periods of abstinence substantially more frequently than subjects receiving lithium or placebo. Fifty-nine percent of the desipramine-treated subjects were abstinent for at least three to four consecutive weeks during the six-week study period, compared with 17% for placebo and 25% for lithium. Cocaine craving reductions were also substantially greater in the desipramine-treated subjects. Establishment of initial abstinence is the first stage in recovery from cocaine dependence. Our findings indicate that desipramine is an effective general treatment, for this first treatment stage, in actively cocaine-dependent outpatients.

Adult↗
PubMed1989

Magnetic field modulation of receptor binding.

Although it is widely held that the magnetic fields encountered during magnetic resonance imaging (MRI) and other procedures have no discernible effect on biological systems, we find that at early times of incubation, the amount of binding of the neurotoxin, alpha-bungarotoxin, to nicotinic acetylcholine receptor is significantly reduced in a constant 2.0-T magnetic field. This finding suggests that steady magnetic fields can directly affect the functional activity of biologically important macromolecules, in this particular case a neurotransmitter receptor.

Animals↗
PubMed1982

Plasma cocaine concentrations during cocaine paste smoking.

Cigarettes containing cocaine paste were administered to experiences volunteer smokers in Peru, and plasma concentrations of cocaine were measured. Cocaine concentrations as high as 462 ng/ml were obtained after only three minutes of smoking cocaine paste. Subjects titrated their rate of consumption so as to achieve remarkably constant plasma concentrations during the smoking period. Areas under curve (AUC), adjusted for dose, were approximately 70% that obtained with oral or intranasal administration of cocaine to different subjects in previous experiments.

Adult↗
PubMed1982

Kinetics of drug effect by distributed lags analysis: an application to cocaine.

The same plasma drug concentration may induce different effects depending on whether the concentration is rising or falling. We described a new method of modeling kinetics of drug effects that can handle such "dissociation" phenomena, that does not depend on compartmental theory, and that allows quantitative comparisons between experiments. As applied to cocaine, it is shown that the resulting models are independent of drug dose or route of administration and give good predictions of the time course of response.

Administration, Intranasal↗
PubMed1982

Cocaine.

Explore the source record for details and available documents.

Chemistry↗
PubMed1982

Intranasal cocaine: dose relationships of psychological effects and plasma levels.

We compared the psychological effects of three doses of intranasal cocaine hydrochloride (.2, .75, and 1.5 mg/kg) with cocaine plasma concentrations in four volunteers. Intranasal lidocaine hydrochloride (.2 mg/kg) was used as a topically active placebo. Peak "high" ratings were related to both dose and peak plasma concentrations. At a given plasma concentration, "high" ratings were greater when plasma levels were increasing than when they were decreasing. This indicates that acute tolerance by tachphylaxis occurred after single doses. The cocaine "high" was a pleasant feeling but was without distinctive sensations. The dramatic effects of intranasal cocaine on the street may be related to larger or repeated doses as well as the setting.

Administration, Intranasal↗