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Biomedical subjects

D B Scott

Publications and source records attributed to D B Scott.

At least 37 records · Page 2Linked to original sources
PubMed1990

A study of the psychometric effects of chlormethiazole in healthy young and elderly subjects.

The pharmacokinetics and effects of chlormethiazole (91 mg intravenously together with 356 mg orally) on psychomotor performance were studied in 10 young (mean age 29 years) and 10 older (mean age 66.2 years) volunteers using an open design. Chlormethiazole affected psychomotor function and decreased subjective arousal in both age groups. The peak effect was found at approximately 30 min, i.e. at the end of the infusion, and performance returned to normal by 3 h. There was no evidence of increased sensitivity of the older subjects to the psychomotor or subjective effects of chlormethiazole. The incidence and type of reported symptoms was also similar in the two age groups. The volume of distribution of chlormethiazole was greater in the old than in the young subjects as was the elimination half-life after intravenous administration. Other pharmacokinetic variables showed no significant differences between young and old subjects.

Administration, Oral↗
PubMed1990

Serious non-fatal complications associated with extradural block in obstetric practice.

A retrospective study of serious non-fatal complications of extradural block in obstetric practice was carried out using a postal questionnaire. Two hundred and three obstetric units in the United Kingdom (responsible for 2,580,000 deliveries from 1982 to 1986 inclusive) responded. A total of 505,000 extradural blocks were performed, 84% for relief of pain in labour and 16% for Caesarean section. Of 108 events reported, five were associated with permanent disability. Neuropathy involving a single spinal nerve, acute toxicity from the local anaesthetic, and problems associated with accidental dural puncture were the commonest complications. This investigation indicates the need for a prospective study. Although rare, serious complications could be reduced further by meticulous technique, while early diagnosis and treatment of untoward events would reduce the incidence of permanent disability.

Anesthesia, Epidural↗
PubMed1990

A comparison of the CNS effects of enprofylline and theophylline in healthy subjects assessed by performance testing and subjective measures.

1. The effects of intravenous infusions of enprofylline, theophylline, and placebo on subjective ratings and on psychological test performance were studied in a double-blind crossover experiment in 12 healthy subjects who abstained from caffeine throughout the experimental procedures. 2. Mean plasma concentrations of enprofylline were: mean 2.9 mg l-1 (range 1.9-3.4). Those for theophylline were: mean 12.1 mg l-1 (range 9.0-14.4). 3. Performance on the auditory vigilance task showed a significant improvement with theophylline compared with both enprofylline and placebo. The correct detection rates (out of 90) were 50.3, 43.4 and 39.1 respectively. A similar effect was seen with finger tapping rates: 404, 394 and 390 taps min-1 respectively. Other measures showed no significant effects, although choice reaction time showed a trend towards faster responses with theophylline. 4. Subjective ratings showed that subjects were significantly more alert with theophylline than with enprofylline. Subjects reported themselves as significantly more dizzy and ill with both active drugs compared with placebo. 5. These results suggest that emprofylline largely lacks the CNS stimulant effects of theophylline, but that the incidence of other unwanted effects of the drugs may be similar.

Acoustic Stimulation↗
PubMed1990

The availability of epidural anaesthesia and analgesia in obstetrics.

This survey analyses the provision of obstetric epidural services on national and regional bases and also by size of obstetric unit. Epidural anaesthesia and analgesia in obstetrics is not readily available to all women who wish for it, or in whom it is recommended on medical grounds, in spite of the recommendations of the Social Services Committee and other advisory bodies. Deficiencies in the provision of facilities are obvious but further analysis at a local level is required to determine the reasons and the remedies.

Analgesia↗
PubMed1989

A cloned DNA probe for the detection of Mycobacterium paratuberculosis.

DNA extracted from Mycobacterium paratuberculosis, which had been isolated from a cow with clinical Johne's disease, was used to make a gene library in the Escherichia Coli expression vector phage lambda gt11. Plaque-lifts were made from the library onto nitrocellulose membranes. These were screened by differential hybridization using radiolabelled chromosomal DNA from M. paratuberculosis and Mycobacterium phlei. By this method six recombinants that hybridized to M. paratuberculosis but not to M. phlei were identified. Three of these, designated lambda gt-R3, lambda gt-R4 and lambda gt-RS, containing DNA inserts of 2.5,1.5 and 3.7 kilobases (kb), respectively, were chosen for further analysis of their insert specificities. Following restriction with the endonucleases EcoRI and BamHI, the digestion fragments from the three recombinants were transferred to nitrocellulose membranes and probed with radiolabelled DNA from M. paratuberculosis and M. phlei. As expected, M. paratuberculosis DNA hybridized to all the fragments. M. phlei DNA hybridized to both the fragments that were generated from lambda gt-R3, to the single fragment from lambda gt-R4 and to two of the three fragments generated from lambda gt-RS. The fragment with which M. phlei DNA failed to hybridize was 0.45 kb in length. Multiple copies of this fragment were made in the plasmid pGEM-2; the plasmid DNA was then harvested and radiolabelled. Designated PAM-1, the radiolabelled material hybridized to a 3.7 kb fragment of EcoRI-digested M. paratuberculosis and to 2.2 kb fragments of similarly digested M. avium serovars 2 and 3. PAM-1 did not hybridize to DNA from the other four mycobacterial species examined or from Nocardia asteroides. The restriction fragment length polymorphism thus demonstrated distinguishes M. paratuberculosis from M. avium serovars 2 and 3.

Journal Article↗
PubMed1989

Disposition kinetics of ropivacaine in humans.

The pharmacokinetic characteristics of a new local anesthetic drug, ropivacaine, were determined after intravenous infusion of 50 mg of the hydrochloride salt into six healthy male volunteers. Results showed that the disposition of ropivacaine can be described by a biexponential function. Its blood clearance (0.72 +/- 0.16 L/min) is intermediate between that of mepivacaine and bupivacaine. Plasma binding averaged 94% +/- 1% and the volume of distribution at steady state based on blood drug concentration was 59 +/- 7 L. The terminal elimination half-life was 111 +/- 62 min.

Adult↗
PubMed1989

Acute toxicity of ropivacaine compared with that of bupivacaine.

The acute central nervous and cardiovascular effects of the local anesthetics ropivacaine and bupivacaine were compared in 12 volunteers in a randomized double-blind manner with use of intravenous infusions at a rate of 10 mg/min up to a maximal dose of 150 mg. The volunteers were all healthy men. They were familiarized with the central nervous system (CNS) toxic effects of local anesthetics by receiving a preliminary intravenous injection of lidocaine. The infusions of ropivacaine and bupivacaine were given not less than 7 days apart. CNS toxicity was identified by the CNS symptoms and the volunteers were told to request that the infusion be stopped when they felt definite but not severe symptoms of toxicity such as numbness of the mouth, lightheadedness, and tinnitus. In the absence of definite symptoms, the infusion was stopped after 150 mg had been given. Cardiovascular system (CVS) changes in conductivity and myocardial contractility were monitored using an interpretive electrocardiograph (which measured PR interval, QRS duration, and QT interval corrected for heart rate) and echocardiography (which measured left ventricular dimensions from which stroke volume and ejection fraction were calculated). Ropivacaine caused less CNS symptoms and was at least 25% less toxic than bupivacaine in regard to the dose tolerated. Both drugs increased heart rate and arterial pressure. Stroke volume and ejection fraction were reduced. There was no change in cardiac output. Although both drugs caused evidence of depression of conductivity and contractility, these appeared at lower dosage and lower plasma concentrations with bupivacaine than with ropivacaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

A fatal accident after epidural anesthesia for cesarean section.

It is a sobering fact that mishaps during the administration of anesthesia sometimes have a way of initiating problems which escalate step by step to a situation of total disaster for the patient. Inexperience and poor judgment often lie behind such tragedies and the following case report is presented not only as an illustration of this, but also as a useful lesson. The authors only became involved in this case after the anesthesiologist concerned made available his account of the clinical events together with the hospital records. For obvious reasons the anesthesiologist's name has not been given, but he has given his full permission to publish this case. A case report is presented in which a healthy 31-year-old a term para II, requested epidural anesthesia for an elective Cesarean section for pelvic disproportion. Repeated attempts to perform epidural anesthesia were necessary. Eventually she developed acute pulmonary edema and resuscitation was not successful. Both mother and fetus died.

Acute Disease↗