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Biomedical subjects

D B Scott

Publications and source records attributed to D B Scott.

At least 73 records · Page 4Linked to original sources
PubMed1985

Isolation and characterization of transposon Tn5-induced symbiotic mutants of Rhizobium loti.

Rhizobium loti NZP2037 and NZP2213, each cured of its single large indigenous plasmid, formed effective nodules on Lotus spp., suggesting that the symbiotic genes are carried on the chromosome of these strains. By using pSUP1011 as a vector for introducing transposon Tn5 into R. loti NZP2037, symbiotic mutants blocked in hair curling (Hac), nodule initiation (Noi), bacterial release (Bar), and nitrogen fixation (Nif/Cof) on Lotus pedunculatus were isolated. Cosmids complementing the Hac, Noi, and Bar mutants were isolated from a pLAFR1 gene library of NZP2037 DNA by in planta complementation and found to contain EcoRI fragments of identical sizes to those into which Tn5 had inserted in the mutants. The cosmids that complemented the mutants of these phenotypic classes did not share common fragments, nor did cosmids that complemented four mutants within the Noi class, suggesting that these symbiotically important regions are not tightly linked on the R. loti chromosome.

DNA Transposable Elements↗
PubMed1984

A study of the effects of zimelidine on the pharmacokinetics and pharmacodynamics of temazepam in healthy volunteers.

In this double-blind two-period crossover study, ten healthy volunteers received either 200 mg zimelidine each morning for 5 days, or placebo on the same schedule. On day 5 they received 20 mg temazepam 2 h after zimelidine or placebo. A battery of psychometric tests and subjective measurements was carried out on days 4 and 5. Blood samples were collected on day 5 for pharmacokinetic analysis of temazepam. All the measures of psychomotor performance showed the effects of temazepam, as did two of the subjective measures, the "alert/drowsy" and "steady/dizzy" visual analogue scales. No effect of zimelidine alone on performance or subjective state was seen. Zimelidine showed no discernible interaction with the effects of temazepam as assessed by subjective reports, by psychomotor tests, or by pharmacokinetic analysis.

Adult↗
PubMed1984

Influence of the addition of potassium to 0.5% prilocaine solution during I.V. regional anaesthesia.

Six volunteers underwent i.v. regional anaesthesia on two occasions using 0.5% prilocaine 40 ml with potassium 0 or 4 mmol litre-1. Addition of potassium produced more rapid sensory blockade to pinprick at five of the six sites tested, although this was statistically significant at only one site (P less than 0.05) and more rapid sensory blockade to pinch with Allis forceps at four of the six sites (n.s.). Recovery of sensory blockade was rapid and only one site showed any significant effect, pinprick blockade being prolonged by potassium (P less than 0.05), although there was no overall effect. It is suggested that the addition of physiological (extracellular) concentrations of potassium to prilocaine for i.v. regional anaesthesia confers no clinical advantage, but that further study of other agents and sites of blockade is required.

Anesthesia, Conduction↗
PubMed1984

Comparison of bupivacaine and etidocaine in extradural blockade.

In a randomized, double-blind study, 40 female patients underwent major gynaecological surgery with extradural anaesthesia provided by 0.75% bupivacaine, 0.75% bupivacaine with adrenaline 5 micrograms ml-1, 1.5% etidocaine or 1.5% etidocaine with adrenaline 5 micrograms ml-1, 20 ml in each case. In all patients the resultant blockade was suitable for intra-abdominal pelvic surgery. Mean maximum spread of analgesia was around T3/4 with all four drugs. Onset of sensory and motor block was more rapid following etidocaine than following bupivacaine. The addition of adrenaline increased the speed of onset of sensory block. Patients receiving etidocaine had a denser motor blockade than those receiving bupivacaine, and the addition of adrenaline led to an increase in the density of the motor blockade. There were no differences in the durations of motor blockade. Objective measurements of the duration of sensory blockade showed that there were no differences between the drugs and that the addition of adrenaline increased the duration of blockade. However, pain returned sooner following etidocaine than bupivacaine, and the additive effect of adrenaline was to increase this period of subjective analgesia.

Acetanilides↗
PubMed1984

Epidural test dose.

Explore the source record for details and available documents.

Anesthesia, Epidural↗
PubMed1984

Bupivacaine and prilocaine in intravenous regional anaesthesia.

Six volunteers underwent intravenous regional anaesthesia of the non-dominant arm on four occasions using two equipotent doses of bupivacaine and prilocaine, administered in a randomised double-blind sequence. Equipotent doses produced similar degrees of motor and sensory blockade. Bupivacaine produced more rapid motor power loss and delayed motor recovery (p less than 0.01). Prilocaine produced more prolonged objective blockade following tourniquet release (p less than 0.01), although this was not clinically useful, and bupivacaine led to a marked prolongation of subjective blockade (p less than 0.01). Increase of dose with both drugs gave more rapid and complete sensory and motor blockade and delayed recovery (p less than 0.05). This was, however, associated with more marked toxicity. It is suggested that in intravenous regional anaesthesia there are no clinical differences between the drugs in equipotent solutions, and that the lower concentrations are the appropriate ones for standard use.

Adult↗
PubMed1984

The effect of chlormethiazole on the hypoxic drive to breathing in normal man.

We have studied the effects of chlormethiazole infusion on the ventilatory response to progressive isocapnic hypoxia in seven healthy volunteers, during both normocapnia and induced hypercapnia. The dose of chlormethiazole was such that it produced the same degree of hypnosis as would be expected from oral administration of two capsules each containing 192 mg of base in arachis oil. Ventilation did not change significantly during chlormethiazole administration. The ventilatory response to hypoxia was unaffected by chlormethiazole during normocapnia and was enhanced during hypercapnia. In these subjects, giving chlormethiazole intravenously was not associated with depression of the resting ventilation nor the hypoxia ventilatory response.

Adult↗
PubMed1983

Haemodynamic effects of induced hypotension with a nitroprusside-trimetaphan mixture.

The haemodynamic effects of a 10:1 mixture of trimetaphan and nitroprusside have been studied before and during the course of surgery, in 12 patients placed in 5 degrees reverse Trendelenburg position. Six patients breathed spontaneously and in six the lungs were ventilated artificially. The mixture had a potent hypotensive action that was almost as rapid in onset and recovery as that produced by nitroprusside alone, but the required dose of each drug was decreased considerably. In patients breathing spontaneously, cardiac output remained unchanged on the induction of hypotension, but it decreased significantly in the IPPV group. Heart rate increased, and stroke volume, peripheral resistance and central venous pressure decreased in both groups. The start of surgery was associated with a need to increase the dose of the hypotensive mixture, and with a further increase in heart rate and decrease in stroke volume. Levelling the operating table produced an increase in cardiac output and discontinuation of the mixture resulted in a rapid return of all measurements towards control values.

Adult↗
PubMed1983

Effects of alaproclate and morphine on the ventilatory response to carbon dioxide in normal man.

The ventilatory response to carbon dioxide was determined in six healthy volunteers given alaproclate alone and combined with morphine. A rebreathing technique was used and the slope of the ventilatory response to carbon dioxide was plotted. A comparison of these responses after alaproclate or a placebo showed no significant difference. Following the administration of morphine i.v., respiration was depressed, but there was no enhancement of the depression of the ventilatory response to carbon dioxide in subjects pretreated with alaproclate.

Adult↗
PubMed1983

Anaesthesia-related surgical mortality.

This is the report of the second of two studies conducted by the Association of Anaesthetists of Great Britain and Ireland based on anonymous reports of deaths within 6 days of anaesthesia. One hundred and ninety-seven detailed reports were received during 1981; 43% were found by assessors to have nothing to do with anaesthesia, 41% to be partly due to, and 16% totally due to anaesthesia. These figures confirm earlier results reported by the same system. It is important to have the opinion of the two clinicians (anaesthetist and surgeon) separately and not to ignore either in a study which attempts to identify aspects of clinical medicine which might be improved.

Aged↗
PubMed1982

Effects of amitriptyline and zimelidine in combination with ethanol.

Six healthy male volunteers took part in this three-period crossover study. In each session, a dose of trial drug -- either placebo, zimelidine 200 mg, or amitriptyline 75 mg -- was given at 09.00 h. Ethanol (50 g) was taken orally at 1200 h. Blood samples were taken for measurement of drug and ethanol concentrations, and body sway and subjective sedation were determined. No differences in the pharmacokinetics of ethanol were seen between the three treatment sessions. Amitriptyline and ethanol showed marked sedative effects, and the results suggest that these two effects may be additive. The combination of amitriptyline and ethanol results in a particularly marked increase in body sway. No sedative nor alerting effect of zimelidine was seen, nor was any interaction between zimelidine and ethanol apparent.

Adult↗
PubMed1982

Spinal anaesthesia with hyperbaric bupivacaine: effects of concentration and volume administered.

A double-blind study was carried out using hyperbaric solutions of bupivacaine to compare the effects of varying the concentration of bupivacaine and the volume of solution administered intrathecally. Fifty-seven patients were studied. Ten patients received each volume of each concentration: 0.5% bupivacaine in 8% dextrose, 2 ml, 3 ml or 4 ml and 0.75% bupivacaine in 8% dextrose, 1.3 ml or 2 ml. A further seven patients received 3 ml of the 0.75% solution. Both solutions consistently produced good nerve blockade. With the 0.5% solution, increases in the volume administered had no effect on the spread of sensory loss, whereas with the 0.75% solution, increasing the volume administered resulted in a significantly greater cephalad spread. The use of 3 ml of this solution was abandoned after seven patients had received it because of the excessive spread. With both solutions, increasing the volume produced a longer duration of action. The use of a 0.75% solution of hyperbaric bupivacaine for spinal anaesthesia did not appear to confer any advantage over the 0.5% solution.

Anesthesia, Spinal↗
PubMed1982

Postoperative glucose tolerance during extradural analgesia.

Thirteen patients undergoing lower abdominal gynaecological surgery were allocated to general anaesthesia (halothane and nitrous oxide) or general anaesthesia plus extradural analgesia (T8-S5). I.v. glucose tolerance tests were performed on the day before surgery and 8 h after skin incision. All patients having extradural analgesia (T8) were pain-free following surgery. Extradural analgesia blocked the hyperglycaemic response to surgery but not the late postoperative cortisol response, although values were significantly less than in the group receiving general anaesthesia alone. Impairment of glucose tolerance and of insulin response to the glucose load in the period after operation were not influenced by extradural analgesia and this may have resulted from insufficient inhibition of the stress-induced release of catecholamines or cortisol, or both, or from blockade of stimulatory efferent sympathetic pathways to pancreatic islets.

Adult↗