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Biomedical subjects

R M Jones

Publications and source records attributed to R M Jones.

At least 217 records · Page 12Linked to original sources
PubMed1986

Vecuronium induced neuromuscular blockade. The effect of increasing dose on speed of onset.

The speed of onset of neuromuscular blockade was measured for increasing doses of vecuronium. Onset times were found to be shorter with larger doses, up to a limit of ED95 X 3 (0.15 mg/kg). Thereafter, increasing the dose, even up to ED95 X 8 (0.4 mg/kg), did not appreciably shorten the time to full neuromuscular blockade. The clinical implications of, and pharmacokinetic basis for, these findings are discussed.

Adult↗
PubMed1986

Profound atracurium induced neuromuscular blockade. A comparison of evoked reversal with edrophonium or neostigmine.

Speed of reversal of profound atracurium induced neuromuscular blockade following edrophonium (0.5 or 1.0 mg/kg) or neostigmine (0.04 or 0.08 mg/kg) was measured using the train-of-four pattern of nerve stimulation. In all patients adequate clinical reversal was present when the ratio of the strength of the fourth to the first twitch (T4 ratio) was 0.5. Both doses of edrophonium were associated with a significantly faster speed of reversal than the smaller dose of neostigmine (p less than 0.05 in both cases). However, the larger dose of neostigmine was associated with a reversal time approaching that of edrophonium. Possible explanations for these findings are discussed in terms of contemporary theories of neuromuscular pharmacology.

Adult↗
PubMed1986

IgE FAST inhibition: a rapid technique for the standardization of pollen allergen extract potency.

An IgE FAST(TM) inhibition protocol has been developed as a rapid in vitro method for determining relative potencies of in vivo allergenic extracts. Results are obtained within one day and correlate well with those of the RAST inhibition protocol (r = .96), making the FAST assay a preferable procedure for inprocess potency determination during the manufacture of standardized allergenic extracts.

Allergens↗
PubMed1985

Interactions between diltiazem and isoflurane. An in vitro investigation in isolated guinea pig atria.

Maximum force of contraction of paced, isolated guinea pig atria was measured in three groups. Atria from animals in group 1 were exposed to isoflurane for 10 min. In group 2, atria were exposed to diltiazem 35 nmol litre-1 alone and in group 3 atria were pre-treated with diltiazem 35 nmol litre-1 before exposure to isoflurane. Maximum depression of contraction was significantly greater in tissue exposed to the combination of diltiazem and isoflurane (group 3) compared with that exposed to isoflurane alone (group 1). Tissue exposed to diltiazem and isoflurane remained significantly more depressed from 15 to 30 min after the administration of isoflurane compared with the depression produced by the volatile agent alone. The results suggest that the calcium antagonist, diltiazem, may modify the effects of isoflurane on myocardial function.

Animals↗
PubMed1985

Comparison of infusions of morphine and lysine acetyl salicylate for the relief of pain after surgery.

The effect of a constant i.v. infusion of lysine acetyl salicylate (LAS) on pain after operation was compared with that of a constant infusion of morphine in 30 patients undergoing unilateral inguinal herniorrhaphy. LAS provided analgesia equivalent to that provided by morphine and was associated with significantly less drowsiness, nausea and vomiting. No patient in either group was noted to suffer from respiratory depression. No untoward side effects were noted during or following the administration of LAS.

Analgesics↗
PubMed1985

Comparison of infusions of morphine and lysine acetyl salicylate for the relief of pain following thoracic surgery.

A double-blind study comparing the effectiveness of a continuous infusion i.v. of lysine acetyl salicylate (LAS) with an infusion of morphine for the treatment of pain following pulmonary surgery is described. Mean pain scores in the two groups were not significantly different at any stage during the 24-h period of study. LAS was not associated with any significantly greater blood loss in the period after operation. The incidence of drowsiness, nausea and vomiting, and the need for antiemetic medication were similar in both groups.

Analgesics↗
PubMed1985

Cardiac rate and rhythm during anaesthesia for dental extraction. A comparison of halothane, enflurane and isoflurane.

Cardiac rate and rhythm were compared in 60 patients having dental extractions under conventional general anaesthesia using halothane, enflurane or isoflurane to supplement nitrous oxide in oxygen. The incidence of arrhythmia was higher in the halothane group when compared with both the enflurane (P less than 0.05) and the isoflurane (P less than 0.05) groups. Heart rates, measured at 1-min intervals, tended to be more rapid in the isoflurane group compared with the other two groups (P less than 0.001 in both instances), and patients anaesthetized with enflurane tended to have more rapid heart rates than those anaesthetized with halothane (P less than 0.001).

Adolescent↗
PubMed1985

Fade characteristics and onset times following administration of pancuronium, tubocurarine and a mixture of both agents.

The onset characteristics of pancuronium, tubocurarine and a mixture of these two neuromuscular blocking drugs were studied during the induction of neuromuscular blockade, using a train-of-four pattern of stimulation. Four characteristics of onset were defined: train-of-four fade = a reduction in the height of the fourth twitch greater than a reduction in the height of the first twitch; latent onset time = time from injection of neuromuscular blocker to a greater than 5% reduction in the first twitch in the train-of-four; total onset time = time to 90% reduction in twitch height; manifest onset time = time from 5% to 90% reduction in twitch height. Tubocurarine was associated with significantly more fade than either pancuronium or the mixture. During the period of study the fade profile of the mixture was almost identical to that of pancuronium alone. The mixture had the most rapid total onset time (100.3 s), tubocurarine the slowest (135.1 s) and pancuronium was intermediate (124.0 s). The mixture and tubocurarine had similar latent onset times, while the mixture and pancuronium had similar manifest onset times.

Adult↗
PubMed1985

Factors affecting train-of-four fade.

The characteristics of the train-of-four response during neuromuscular blockade with two agents, atracurium and vecuronium, have been compared. During onset of blockade, at 75% depression of the initial twitch, atracurium was associated with significantly more fade than was vecuronium, and larger doses of atracurium were associated with less fade than smaller doses of the same agent. In addition, with both agents, the degree of fade at a given amount of initial twitch depression was significantly less during onset than during spontaneous offset of action. The degree of train-of-four fade bears no fixed relationship to depression of the initial twitch.

Adult↗
PubMed1985

Anaesthetic carrier gases. Their effect on middle-ear pressure peri-operatively.

The effects of three different anaesthetic carrier gases on middle-ear pressure in the operative and postoperative periods was assessed. Patients receiving oxygen and oxygen-enriched air did not have significant changes in middle-ear pressure. The changes associated with the use of nitrous oxide as the carrier gas were reversed with return of pharyngeal reflexes or after prolonged inhalation of 100% oxygen. In patients undergoing middle-ear surgery or those with pre-existing middle-ear disease, we suggest that oxygen-enriched air is the anaesthetic carrier gas of choice.

Adult↗
PubMed1985

Parenteral aspirin for pain relief in day-case dental anaesthesia. A randomised double blind placebo controlled trial.

Forty patients undergoing day-case anaesthesia for surgical extraction of third molar teeth received either lysine acetylsalicylate 1.8 g in 10 ml of saline intravenously or a placebo injection of 10 ml of saline intravenously just prior to induction of anaesthesia. Lysine acetylsalicylate was associated with a significantly more satisfactory postoperative recovery overall. However, there was no significant difference in mean pain scores between the two treatment groups at 1, 6, 12 or 24 hours following administration. Both treatment groups self administered additional oral analgesics to the same extent during the first 24 hours following surgery.

Adolescent↗
PubMed1985

Carbon-11 choline: synthesis, purification, and brain uptake inhibition by 2-dimethylaminoethanol.

We report an improved method for the synthesis and purification of [11C]methylcholine from the precursors [11C]methyliodide and 2-dimethylaminoethanol (deanol). Preparation time, including purification, is 35 min postbombardment. Forty millicuries of purified injectable [11C]choline were produced with a measured specific activity of greater than 300 Ci/mmol and a radiochemical purity greater than 98%. The decay corrected radiochemical yield for the synthesis and purification was approximately 50%. Residual precursor deanol, which inhibits brain uptake of choline, is removed by a rapid preparative high performance liquid chromatography (HPLC) method using a reverse phase cyano column with a biologically compatible 100% water eluent. Evaporation alone did not completely remove the deanol precursor. Brain uptake of the [11C]choline product was six times greater after HPLC removal of deanol because doses of less than 1 microgram/kg significantly inhibit [14C]choline brain uptake.

Animals↗
PubMed1984

Naproxen disposition in patients with alcoholic cirrhosis.

Chronic liver disease is known to alter the absorption and disposition of many drugs. To assess the influence of chronic alcoholic liver disease on the disposition of naproxen, we administered the drug both as a single dose and to steady state to 10 individuals with alcoholic cirrhosis and to 10 healthy controls. Plasma and serum samples collected after naproxen dosing were assayed for both total and (following equilibrium dialysis) unbound drug concentration. Clearance calculated based on both total and unbound naproxen concentration revealed no change in total plasma clearance of the drug at steady state but a marked reduction of approximately 60% in clearance based on unbound drug. Naproxen volume of distribution changed only minimally. Because clearance based on unbound drug concentration at a given dosing rate determines the plasma or blood free drug concentration, this concentration may increase significantly in patients with alcoholic liver disease given usual doses of naproxen. Unbound drug concentration is thought to determine the pharmacologic effect of a drug. We therefore recommend that naproxen dosing be reduced by at least half in patients with chronic alcoholic liver disease. In the absence of data to the contrary, this recommendation can be extended to individuals with other forms of hepatic disease.

Adult↗
PubMed1984

Recovery characteristics following antagonism of atracurium with neostigmine or edrophonium.

The evoked reversal characteristics of atracurium were studied in 21 patients using edrophonium or neostigmine and a train-of-four pattern of stimulation. Reversal of residual atracurium -induced neuromuscular blockade was significantly more rapid using edrophonium compared with neostigmine. The ratio of the fourth twitch in the train-of-four to the first twitch--the T4 ratio--was significantly greater when the first twitch (T1) had recovered to 75% of control T1, using edrophonium compared with neostigmine. A T4 ratio of 0.5 was confirmed to be compatible with the reliable and safe reversal of atracurium -induced neuromuscular blockade.

Adult↗