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Biomedical subjects

R Keenan

Publications and source records attributed to R Keenan.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effects of carbamazepine on acute responses to smoked cocaine-base in human cocaine users.

A double-blind, placebo-controlled cross-over study was conducted to determine the effects of carbamazepine on the acute physiological and subjective responses to a single dose of smoked cocaine-base. Male cocaine users (N = 6) were given 400 mg carbamazepine or placebo, each for a period of 5 days. At the end of the 5-day period, a 40 mg dose of smoked cocaine was administered. The results showed a significantly higher heart rate, diastolic blood pressure elevation, and blood pressure-heart rate product under the carbamazepine compared to the placebo condition. There were no effects of carbamazepine on the subjective responses from cocaine. The increase in cardiovascular functions indicates a need to be cautious in the use of carbamazepine in the treatment of cocaine abusers.

Administration, Inhalation↗
PubMed1991

Does histologic acute rejection in lung allografts predict the development of bronchiolitis obliterans?

Clinical acute lung rejection (AR) occurs in lung allografts usually within 50 days after transplantation. While perivascular infiltrates characterize AR, with moderate-to-severe acute rejection small airway injury occurs. We investigated the significance of small airway injury in AR and its relationship to the development of bronchiolitis obliterans (OB) in 11 recipients of combined heart-lung or double-lung allografts. In general, the intensity and persistence of early acute rejection episodes associated with injury to bronchioles correlated with the development of histologic bronchiolitis obliterans. Early AR may "prime" lymphocytes for subsequent respiratory epithelial injury and airway fibrosis late in the postoperative period.

Adult↗
PubMed1991

Long-term use of nicotine vs placebo gum.

Medical patients (n = 315) who wished to quit smoking were randomly assigned in a double-blind manner to receive either nicotine or placebo gum. Subjects were advised to stop gum use by 4 months. Among abstinent smokers, 46% of those receiving nicotine gum and 17% of those receiving placebo gum used the gum beyond the recommended 4-month period. By 10 months after cessation 17% of quitters receiving nicotine gum and 6% receiving placebo gum were still using gum. Gradual reduction of nicotine gum did not result in withdrawal and cessation of nicotine gum did not increase the probability of relapse to smoking or weight gain. We conclude that use of nicotine gum is due, in part, to the effects of nicotine; however, long-term use is uncommon.

Adult↗
PubMed1990

A method for delivery of precise doses of smoked cocaine-base to humans.

Despite increasing smoked cocaine-base use, there have been relatively few parametric studies in this area. The major reason for the limited number of studies is the lack of a simple procedure for the administration of precise doses of smoked cocaine-base to human volunteers. This paper describes a new method that allows for the delivery of precise doses of smoked cocaine-base. A complete description of the method and the precision of the administration procedure are presented. Furthermore, a study is described which was undertaken to determine: 1) the reproducibility of peak blood cocaine levels when the same dose of cocaine was given on two separate occasions; and 2) the dose-related effects on smoking topography, biochemical, physiological and subjective measures. Subjects (N = 5) were administered three doses of cocaine-base (10, 20 and 40 mg). Four subjects were given repeated doses of cocaine-base. Subjects were blind to the dose and in most cases randomly assigned to different doses. The results showed: 1) a significant correlation of peak whole blood cocaine concentrations among similar doses within subjects (r = .99); 2) no significant effects of dose on smoking topography; and 3) significant dose effects for whole blood cocaine concentrations, heart rate and systolic blood pressure.

Adult↗
PubMed1989

The effects of varying cigarette deprivation duration on cognitive and performance tasks.

The effects of varying times of cigarette deprivation on cognitive and performance tasks were examined. This study employed a between-subjects design in which five groups of smokers (9-10 subjects in each group) were compared on a vigilance task and cognitive measures as a function of length of deprivation (0, 2, 4, 8, or 24 hours). Each subject was tested during baseline ad-lib smoking and at one of the deprivation durations. Difference scores were compared between the 0-hour group and the 2-, 4-, 8-, and 24-hour groups. The results showed that there were no significant withdrawal effects on the measures at 2, 4, and 8 hours after cigarette deprivation with the exception of poorer performance on the Trail Making Test (B) at 4 hours, However, there were significant withdrawal effects at 24-hours deprivation. These included increased mean reaction time, increased variability in reaction time, and increased errors of commission on the vigilance task. There were near significant changes at 24-hours deprivation on the Trail Making Test (B) and Symbol Digits Modalities.

Adolescent↗
PubMed1986

Nutritional knowledge of medical staff and students: is present education adequate?

Knowledge of nutritional principles and attitudes to nutrition education of a group of clinical medical students and junior hospital doctors were examined by questionnaire. The percentage of correct answers to factual questions was 50.8 for students and 58.5 for doctors. Both groups considered that their teaching was inadequate and over 95 per cent requested education in applied nutrition. Undergraduate instruction by both doctors and dietitians was advocated as appropriate to the final clinical years.

Attitude↗
PubMed1985

Failure of prophylactic barbiturate coma in the treatment of severe head injury.

In certain subgroups of severely head-injured patients, the mortality rate remains unacceptably high. The authors describe a randomized, controlled trial of prophylactic pentobarbital therapy in a group of these patients. Pentobarbital was started as soon as possible after the head injury, regardless of the intracranial pressure (ICP), and was continued for a prescribed period of time. The study included 53 consecutive head-injured patients over the age of 12 years, who had either an acute intradural hematoma (subdural and/or intracerebral, large enough to warrant surgical decompression), or no mass lesion but whose best motor response was abnormal flexion or extension. All patients in the study were randomly assigned to a control group (26 cases) or a pentobarbital-treated group (27 cases) once the diagnosis had been made and informed consent obtained. All patients were treated with the same protocol of aggressive resuscitation, prompt diagnosis and treatment of mass lesions, and intensive care, with close follow-up monitoring. The randomization was effective in producing a close match between the control and treated groups with respect to age, sex distribution, cause of injury, neurological status, intracranial lesions, prevalence of early systemic insults, midline shift, and initial ICP. Outcome was essentially the same in each group. There was no difference between groups in the incidence of elevated ICP, the duration of ICP elevation, or the response of ICP elevations to treatment. Arterial hypotension occurred in 14 patients (54%) in the treated group and only two patients (7%) in the untreated group. Based on these data the authors cannot recommend the prophylactic use of pentobarbital coma in the treatment of patients with severe head injury. They also believe that its use is accompanied by significant side effects which can potentially worsen the condition of a patient with severe head injury.

Adolescent↗
PubMed1981

Pulmonary metastases from a basal cell carcinoma.

Although basal cell carcinomas are the commonest malignant condition of the skin (Borel 1973) pulmonary metastases are rare; it appears that only 30 authenticated cases have been reported (Sakula 1977). A further case is described of a man aged 64 who presented severe dyspnoea and who for 12 years had harbored an untreated ulcerating lesion of the abdominal wall shown histologically to be a basal cell carcinoma. Chest radiography showed metastatic disease confirmed histologically to be identical to the ulcerating skin lesion. Unfortunately, because of the severe respiratory condition, no definitive treatment was indicated and the patient died of respiratory failure 2 weeks following discharge.

Abdominal Muscles↗