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Biomedical subjects

C E Cook

Publications and source records attributed to C E Cook.

At least 37 records · Page 2Linked to original sources
PubMed1992

Evaluation of a 1-year levonorgestrel-releasing contraceptive implant: side effects, release rates, and biodegradability.

OBJECTIVE: To determine the release rates, effects on ovulation, and side effects of two lengths of a biodegradable, subdermal contraceptive implant containing levonorgestrel in a caprolactone capsule. DESIGN: Phase II randomized clinical trial. SETTING: Public family planning clinic at an urban general hospital. PARTICIPANTS: Forty-eight healthy, parous, ovulating volunteers. INTERVENTION: Subjects were randomly assigned either a 2.5- or a 4.0-cm contraceptive capsule that was worn under the skin of the upper arm for 1 year if not removed earlier for other reasons. MAIN OUTCOME MEASURES: Serum concentrations of levonorgestrel, progesterone, estradiol, and lipoproteins were measured as were metabolic parameters. Vaginal bleeding and other side effects were recorded. After implant removal, remaining levonorgestrel, capsule viscosity, and molecular weight were measured. RESULTS: The 4-cm implant provided serum concentrations of levonorgestrel ranging from 0.65 ng/mL shortly after insertion to 0.20 ng/mL at 12 months, but the 2.5-cm implant resulted in levels too low for contraception. The 4-cm implant suppressed ovulation in approximately 80% of cycles over 1 year of use, but the 2.5-cm implant failed to suppress ovulation. The implants were rapidly and easily inserted and removed. They retained structural integrity through 1 year of use. Of 48 subjects, 32 had abnormal bleeding patterns; the mean number of days of bleeding per month was 7 with 23 days between episodes. Women using capronor maintained normal metabolic parameters except that low-density lipoprotein decreased slightly. CONCLUSIONS: The 4.0-cm implant is a promising contraceptive. There were no important metabolic effects, but there were bothersome minor side effects typical of progestin-only contraception.

Abdominal Pain↗
PubMed1992

Influence of age, performance status, body weight, and tumor type in individuals with cancer on the disposition of warfarin and its enantiomers: Department of Veterans Affairs cooperative study number 75.

Plasma warfarin and its R,S enantiomer concentrations, one-stage prothrombin times, and mean daily warfarin doses were analyzed in 196 patients given warfarin. These individuals were part of a controlled clinical trial that examined the effect of warfarin as an adjuvant to "standard" treatment in a variety of malignancies. Neither the plasma warfarin concentration nor the daily warfarin dose required to produce a given degree of prothrombin-time prolongation was influenced by age or body weight in these subjects. When the data were analyzed by performance status, we noted several variations of interest. Individuals with different tumor types demonstrated disparities in warfarin disposition. Patients with colorectal cancer, for example, required lower mean daily warfarin doses to achieve a given degree of one-stage prothrombin time prolongation. Analysis of warfarin enantiomers (R,S) in a selected group of patients demonstrated a lower-than-normal ratio (2:1) for the colorectal cancer group (1.42:1) because of an apparent decrease in the plasma R component. In contrast, patients with head and neck cancer demonstrated a ratio of 2.85:1, and the R component was elevated. Warfarin disposition and the effect of warfarin on vitamin K-dependent clotting factor production were altered in the patients with cancer reported in this study. The mechanisms for these alterations are complex and not completely understood.

Aging↗
PubMed1991

Clinical effects of methamphetamine vapor inhalation.

Despite the increasing popularity of crystalline methamphetamine ("ice") vapor inhalation, no investigations have reported drug plasma concentrations and effects. Under controlled laboratory conditions, six subjects were studied. Plasma concentrations of methamphetamine were determined, and subjective and cardiovascular effects were measured. Methamphetamine appeared in plasma rapidly, increased slowly over the next four hours and then progressively declined. The dose of methamphetamine administered produced modest ratings of subjective drug effects, and moderate changes in cardiovascular parameters. Both subjective and cardiovascular effects rapidly decreased despite the presence of sustained concentrations of methamphetamine in plasma.

Administration, Inhalation↗
PubMed1991

The pharmacologic effects of daily marijuana smoking in humans.

Six healthy male, paid volunteers smoked one NIDA cigarette containing 1.0% THC each day for 13 consecutive days. They were tested before and after the period of drug administration by the following procedure: the subjects smoked one NIDA marijuana cigarette containing 1.0% THC followed 15 minutes later by the intravenous infusion of 52 micrograms/min of deuterated THC for 50 minutes. The THC plasma concentrations, ratings of "high" and heart rate effects produced by the combined drug administration were measured, and absolute bioavailability of smoked THC was calculated on Days 1 and 22. Statistical analyses indicate that the only significant changes induced by daily marijuana exposure were in cardioacceleration.

Adult↗
PubMed1991

Clinical effects of daily methamphetamine administration.

This study investigated alterations in the disposition and pharmacodynamics of methamphetamine HCl after daily administration. Six male paid volunteers familiar with the use of amphetamines participated. Each subject was administered 10 mg of methamphetamine HCl as a slow-release preparation (Desoxyn Gradumets) at 9 a.m. for 13 consecutive days (days 2-14 of the study). On days 1 and 15 the subjects were challenged with 10 mg of oral deuterated methamphetamine HCl. Deuterated drug was used to differentiate plasma concentrations of challenge doses from those of daily doses. The heart rate, subjective perception of "high," and plasma concentrations of methamphetamine were examined on days 1 and 15. Repeated ANOVA measures indicate that a significant decrease in heart-rate acceleration in response to methamphetamine challenge occurred on day 15 [F(1,5) = 8.26, p less than or equal to 0.035]. However, no significant change in either the subjective ratings of "high" or the plasma concentrations of deuterated methamphetamine occurred. These findings indicate that the disposition of methamphetamine and its subjective effects were not altered by this period of daily exposure to a low dose of the drug. In contrast, tolerance to the heart-rate accelerating effect was observed.

Adult↗
PubMed1990

Application of countercurrent chromatography/thermospray mass spectrometry for the identification of bioactive lignans from plant natural products.

The versatility and resolving power of countercurrent chromatography (CCC) has been demonstrated with a newly developed analytical high-speed planet centrifuge system. Interfacing countercurrent chromatography with mass spectrometry (MS) provides a new analytical methodology that integrates the advantages of countercurrent chromatography with the low detection limit and identification capability of mass spectrometry. In this paper the capability of thermospray CCC/MS is demonstrated in identifying and validating the bioactive and structurally known lignans from a crude extract of Schisandra rubriflora Rhed et Wils, a traditional Chinese herbal medicine for treatment of hepatitis.

Chromatography↗
PubMed1988

Interaction between marihuana and ethanol: effects on psychomotor performance.

This is a report of the results of a placebo-controlled study in which the effects of the interaction between ethanol and marihuana on drug plasma concentrations, subjective ratings of intoxication, heart rate acceleration, and psychomotor performance were investigated. Six healthy, male, paid volunteers, moderate users of ethanol and marihuana, participated in the study. Ethanol (0.42 g/kg, 0.85 g/kg, or placebo) was administered over a 30-min interval. Fifteen minutes later the subjects smoked, in their customary manner, NIDA cigarettes containing 2.4% or 0.0004% (placebo) delta-9-tetrahydrocannabinol (THC). Each subject was tested in a single-blind, latin-square crossover design with the following six conditions: placebo ethanol/placebo marihuana; low dose ethanol/placebo marihuana; high dose ethanol/placebo marihuana; placebo ethanol/marihuana; low dose ethanol/marihuana; and high dose ethanol/marihuana. The variables measured in the study were: (a) subjective rating of ethanol and/or marihuana intoxication; (b) heart rate; (c) accuracy and latency of response in the Simulator Evaluation of Drug Impairment (SEDI) task; (d) blood ethanol concentration by gas chromatography; and (e) plasma concentration of THC by radioimmunoassay. The results indicate that the decrements due to ethanol in performance of skills necessary to drive an automobile were significantly enhanced by marihuana in an additive and perhaps synergistic manner. The administration of ethanol prior to marihuana smoking did not produce significant effects on the subjective rating of "high," heart rate acceleration, or THC plasma concentration.

Adult↗
PubMed1987

Mammogram interpretation by physician assistants.

The objective of this study was to determine whether a health maintenance organization (HMO) desirous of providing low-cost, quality mammography could employ physician assistants (PAs) to interpret mammograms under the supervision of HMO radiologists. After intensive training in mammographic interpretation, four PAs individually interpreted 727 mammograms of 470 normal breasts, 75 breasts with benign breast masses, and 182 breasts with cancer. The interpretations by the PAs were more sensitive and as specific as those made by six HMO radiologists who interpreted the same cases, and as effective as those by radiologists described in the literature. In receiver-operating-characteristic curve analysis, the areas under curves for PAs were larger than those under curves for radiologists. Interpretations by PAs took less time and cost less than did those by radiologists; the dispositions recommended by PAs were similar to those recommended by radiologists. We conclude that properly trained, evaluated, and supervised PAs can interpret mammograms. Legal, practical, and ethical considerations dictate that this can best be accomplished under the direction of radiologists who are well trained in mammography.

Female↗