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Biomedical subjects

D B Scott

Publications and source records attributed to D B Scott.

At least 109 records · Page 6Linked to original sources
PubMed1980

Effect of baricity on spinal anaesthesia with amethocaine.

Amethocaine 1% solution was mixed with equal volumes of water, 0.9% saline or 10% dextrose to prepare respectively, hypobaric, isobaric and hyperbaric solutions which were compared for intradural spinal anaesthesia in 60 patients. Thirty patients received 10 mg and 30 patients received 15 mg of amethocaine. Injections were made with the patients in the lateral recumbent position and the operating table was horizontal during and after injection. Equal numbers of patients and equal numbers of males and females received hypobaric, isobaric and hyperbaric solutions. The mean spread of analgesia after the hyperbaric solution was five dermatomes greater than after the other two solutions, but the extent of analgesia was not significantly different whether amethocaine 10 mg or 15 mg was injected. The mean duration of analgesia after the hyperbaric solution was 285 min compared with 332 min and 360 min after the isobaric and hypobaric solutions respectively. The mean duration of analgesia after amethocaine 15 mg was significantly greater than after 10 mg.

Adult↗
PubMed1980

Haemodynamic changes following buprenorphine and morphine.

Twenty-five women were investigated on the day after lower abdominal surgery in a single-blind non-cross-over trial to assess and compare the haemodynamic effects of intravenous injections of buprenorphine 0.3 mg and morphine 7.5 mg. Arterial blood pressure was measured by sphygmomanometry and cardiac output by thoracic impedance cardiography. Arterial blood pressure was significantly reduced following both drugs (p < 0.05), although the mean decrease in systolic arterial pressure was less than 8 mmHg. However, in one patient in each group the decrease was more than 20 mmHg. Cardiac output decreased but the mean reduction was less than 5%. The greatest individual decreases were 21% after buprenorphine and 30% after morphine. Myocardial contractility, assessed by systolic time indices, did not appear to change. There were no consistent differences in the haemodynamic effects of the two drugs.

Abdomen↗
PubMed1979

The biosynthesis of nitrogenase MoFe protein polypeptides in free-living cultures of Rhizobium japonicum.

The biosynthesis of the constituent polypeptides of nitrogenase component I (Rj 1) in free-living cultures of Rhizobium japonicum (strain 110) was investigated under different growth conditions. Cells were pulse-labelled and the proteins analysed by one and two-dimensional gel electrophoresis. The positions of the constituent Rj 1 polypeptides were identified by co-electrophoresis with purified Rj 1 isolated from bacteroids of soybean nodules, and by comparison with an immunoprecipitate from a culture induced for nitrogenase. The synthesis of the proteins preceded any detectable enzyme activity and increased with time, reaching a maximum after 3 days. At this time, between 6 and 8% of the total sodium dodecyl sulfate-soluble protein synthesized was Rj 1. Exposure to air led to a dramatic decrease in the rate of Rj 1 synthesis, with almost complete regression after 20 min. In the presence of KNO3, there was no nitrogenase activity, but the proteins were present in similar amounts (7%) as the control culture. When mannitol and glycerol were used as the sole carbon sources, the amount of Rj 1 synthesized was extremely low.

Gluconates↗
PubMed1979

Pharmacokinetic and clinical pharmacological studies with mepivacaine and prilocaine.

The tolerance and pharmacokinetic properties of mepivacaine and prilocaine were compared following i.v. infusion of 250 mg (0.88 and 0.97 mmol respectively) of each drug in five healthy volunteers. Side-effects were minor and occurred in only two subjects during the infusion of mepivacaine. Plasma concentrations of mepivacaine were greater in each subject than the corresponding values for prilocaine. The elimination half-life of mepivacaine was generally longer than that for prilocaine, whereas the total body clearance of prilocaine was consistently greater than the corresponding value for mepivacaine. For each subject the clearance of prilocaine substantially exceeded normal heptic blood flow and therefore an extra-hepatic site of metabolism of prilocaine has been postulated.

Adult↗
PubMed1979

Cardiovascular effects of prenalterol (H133/22) in normal man.

1 Prenalterol, (S-(-)-1-(4 hydroxyphenoxy)-3-isopropylaminopropanol-2 hydrochloride) a cardio-selective beta-adrenergic receptor agonist, was infused intravenously into six normal male volunteers to determine the cardiovascular effects of this drug. 2 On different occasions, each volunteer received a placebo infusion, an infusion of 0.5 mg prenalterol and an infusion of 1 mg prenalterol. Cardiac output (impedance cardiography), arterial pressure (sphygmomanometry), heart rate and ECG were measured throughout. 3 Prenalterol produced a statistically significant increase in cardiac output and at the end of the infusion this increase was 24% with 0.5 mg and 29% with 1 mg, mainly due to an increase in stroke volume (18% and 17%) with a lesser change in heart rate (+2 and +7 beats/min). Pulse pressure increased but mean arterial pressure showed little change. Peripheral resistance fell by 18% and 20%. As indicated by systolic time indices myocardial contractility increased. 4 Prenalterol at plasma concentrations in excess of 20 nmol l-1 produced significant inotropic effects but did not markedly increase heart rate at concentrations of 60 nmol l-1.

Adrenergic beta-Agonists↗
PubMed1979

Effect of cyclic guanosine 3',5'-monophosphate on nitrogen fixation in Rhizobium japonicum.

The addition of exogenous cyclic guanosine 3',5'-monophosphate (cGMP) at a concentration of 0.1 mM to a free-living culture of Rhizobium japonicum 3I1b110 was found to completely inhibit the expression of nitrogenase activity and markedly inhibit the expression of hydrogenase and nitrate reductase activities. The effect was specific for cGMP. Experiments on the in vivo incorporation of radioactive methionine and subsequent analysis of the labeled proteins on polyacrylamide gels showed that the biosynthesis of nitrogenase polypeptides was inhibited. It appears that the time of addition of cGMP is important since the effect was only seen during the early stages of nif gene expression. The intracellular level of cGMP was found to respond to physiological changes in the cell, and there was a fall in cGMP concentrations when nitrogenase was induced. Microaerophilic-aerobic shift experiments showed that intracellular levels increased from 0.25 pmol/mg of cell protein under microaerophilic conditions to 2.6 pmol/mg of cell protein under aerobic conditions, suggesting that the cellular pool size of cGMP may be under redox control.

Cyclic GMP↗
PubMed1978

Effects of adrenaline and the concentration of solution on extradural block with etidocaine.

Forty patients allocated to four groups received extradural injections of etidocaine for the performance of lower abdominal surgery. Twenty millilitre of the 1% or 1.5% solutions with or without adrenaline (1:200 000) was given in a double-blind manner. The addition of adrenaline to etidocaine did not significantly prolong the duration of analgesia, but it produced significant more motor block. Etidocaine 1.5% caused significantly longer durations of analgesia and more motor block than the 1% solution. The spread of sensory analgesia was similar with all four solutions of local anaesthetic agent.

Acetanilides↗
PubMed1978

Gastric emptying following hysterectomy with extradural analgesia.

Using the rate of absorption of paracetamol following oral administration of the drug, gastric emptying was measured in 21 patients following hysterectomy. Gastric emptying was inhibited markedly in patients receiving narcotic analgesia after operation, but only a moderate delay was observed in patients undergoing extradural analgesia.

Acetaminophen↗
PubMed1978

Circulatory effects of labetalol during halothane anaesthesia.

Labetalol is a drug possessing both alpha and beta adrenergic receptor blocking properties. Its possible use in induced hypotension during halothane anaesthesia has been investigated. It causes a satisfactory decrease in arterial pressure unaccompanied by tachycardia. The circulatory effects of the drug during halothane anaesthesia, both with spontaneous and controlled respiration, have been measured and compared with those of halothane alone. In patients anaesthetised with 1% halothane, labetalol, with both spontaneous and controlled ventilation, was associated with a reduction in MAP from 71.5 mmHg to 54.0 mmHg (P less than 0.001) and 66.8 mmHg to 50.4 mmHg (P less than 0.001) respectively. This reduction was associated with decreases in Qt of 18% and 12% respectively. In the presence of labetalol, with 3% halothane and spontaneous respiration, the depressant effects of the anaesthetic on the heart became rapidly apparent: Qt was reduced by a further 28%. In patients not receiving labetalol, the depressant effects of 3% halothane were frequently countered by the positive inotropic effects of hypercarbia.

Adult↗
PubMed1978

Propranolol in thyrotoxicosis. Cardiovascular changes during thyroidectomy in patients pre-treated with propranolol.

The cardiovascular changes during anaesthesia and thyroidectomy have been studied in seven thyrotoxic patients prepared with propranolol. The heart rate and cardiac rhythm remained very stable throughout surgery. A 20% increase in mean arterial pressure occurred during surgical stimulation. A decrease in cardiac output, due to decreased stroke volume, occurred during surgical stimulation. A decrease in cardiac output, due to decreased stroke volume, occurred during surgery, reaching a maximum of 21% during ligation of the thyroid vessels and returning to pre-operative values by the end of surgery. The fall in cardiac output was accompanied by raised central venous pressure and raised total peripheral resistance.

Adult↗