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Biomedical subjects

J Dixon

Publications and source records attributed to J Dixon.

At least 163 records · Page 9Linked to original sources
PubMed1986

Meptazinol versus pethidine for postoperative pain relief in children.

A double-blind, randomised, clinical trial was undertaken comparing intramuscular meptazinol (1 mg/kg) with intramuscular pethidine (1 mg/kg) for the relief of post-tonsillectomy pain, in 100 children under 15 years of age. Pethidine provided better analgesia in those patients who were awake after 30 minutes, but thereafter no statistically significant differences between the degree of pain relief could be detected. Meptazinol caused less sedation than pethidine, in that significantly more patients were awake after 40 minutes in the meptazinol group. The incidence of nausea and vomiting was similar in patients of both groups.

Azepines↗
PubMed1986

Comparison of diflunisal and acetaminophen with codeine in the treatment of initial or recurrent acute low back strain.

Effective pain relief and patient tolerance and acceptance are essential in outpatient management of mild to moderate pain of acute low back strain. This study evaluated the efficacy, tolerability, and acceptability of diflunisal and acetaminophen with codeine in patients with mild to moderate pain after an initial or recurrent acute low back strain. Both drugs demonstrated equipotent analgesic efficacy; however, diflunisal was superior to acetaminophen with codeine for patient tolerability and acceptability. The results demonstrated that the study drugs were effective in treating mild to moderate pain caused by acute low back strain in an ambulatory care setting.

Acetaminophen↗
PubMed1985

Responses of atherosclerotic aorta to argon laser.

Lasers have been advocated to resect atherosclerotic plaques in the cardiovascular system, yet little information is available regarding the effects of laser on the range of occlusive lesions seen in the peripheral arterial tree. This study was conducted to assess the risk of perforation in human cadaveric aorta involved with variable degrees of atherosclerosis. Ten fresh segments of atherosclerotic human aorta were graded for extent of atherosclerosis, then subjected to argon laser energy within 48 hours. Using air as the conduction medium and with the fiber tip 2 or 5 mm from the vessel wall, the argon laser was applied to matched calcified and non-calcified arteries at 3.0-7.0 W and 10.0-13.5 W with energy density identical for matched pairs. Results were compared among segments which were normal in appearance or had only fatty streaks grossly with those with gross regional wall calcification. The mean penetration time (T) for calcified and non-calcified lesions at low and high power outputs was compared. (table; see text) Mean time to perforation and range of time necessary to produce perforation were greater in calcified than non-calcified segments at all power levels employed. These data suggest that atherosclerotic lesions vary in their response to argon laser. The presence of calcium may preclude resection of some plaques and protect against wall perforation.

Aortic Diseases↗
PubMed1985

Dopexamine: a novel agonist at peripheral dopamine receptors and beta 2-adrenoceptors.

Dopexamine is an agonist at peripheral dopamine receptors and at beta 2-adrenoceptors. Dopexamine has approximately one-third the potency of dopamine in stimulating the vascular DA1-receptor in the dog, resulting in a fall in renal vascular resistance of 20% at 2.3 X 10(-8) mol kg-1 (i.a.). Prejunctional DA2-receptors are also stimulated by dopexamine, resulting in a reduction of neurogenic vasoconstriction in the rabbit isolated ear artery (IC50 of 1.15 X 10(-6)M) and of neurogenic tachycardia in the cat (ID50 of 5.4 X 10(-8) mol kg-1, i.v.), with a potency six and four times less respectively than that of dopamine. By contrast, dopexamine is approximately 60 times more potent than dopamine as an agonist at the beta 2-adrenoceptor of the guinea-pig isolated tracheal chain, with an EC50 of 1.5 X 10(-6)M. Both dopexamine and dopamine are weak agonists at the guinea-pig atrial beta 1-adrenoceptor over the concentration range 10(-7) to 10(-4) M, but dopexamine has an intrinsic activity of only 0.16 relative to dopamine. Dopexamine does not stimulate postjunctional alpha 1- or alpha 2-adrenoceptors in the canine isolated saphenous vein, whereas dopamine is an agonist, approximately 120 times less potent than noradrenaline. Unlike dopamine and salbutamol, dopexamine does not cause arrhythmias in the guinea-pig isolated perfused heart at doses of up to 10(-5) mol, which is a thousand times the minimum cardiostimulant dose. The combination of agonist properties at peripheral dopamine receptors and at beta 2-adrenoceptors, with little or no activity at alpha- and beta 1-adrenoceptors gives dopexamine a novel pharmacological profile. This may confer advantages over dopamine in the treatment of acute heart failure.

Adrenergic Agonists↗
PubMed1985

Combination therapy with pulsed methylprednisolone in rheumatoid arthritis.

Pulsed methylprednisolone (PMP) has been shown to produce clinical improvement and reduction in the ESR and acute phase protein concentrations in patients with active rheumatoid arthritis and has been advocated for use either as an alternative to slow-acting antirheumatoid drugs (SAARDs) or in conjunction with SAARDs to accelerate the response to treatment. To test these potential roles for PMP 45 patients with active RA were randomly allocated to treatment with PMP alone, PMP + sulphasalazine (SAS - at a maintenance dose of 2.0 g/day), or PMP + D-penicillamine (DPA - at a maintenance dose of 500 mg/day). In each case three 1 g intravenous infusions were given on alternate days during the first week of the trial. Patients were monitored for 24 weeks by standard clinical and laboratory measurements. All three treatment groups showed significant clinical and laboratory improvements at two weeks. With PMP + DPA and PMP + SAS these improvements were sustained and were not significantly different in these two treatment groups. However, in the 'PMP only' group ESR and CRP rose to pretreatment values by eight weeks. Twelve patients withdrew from the study owing to a relapse of the RA. No serious adverse effects were seen in the 'PMP only' group. Both combination regimens were well tolerated; adverse effects seen were attributable to either DPA or SAS. We conclude that PMP alone is insufficient for treatment of RA but can be used successfully in combination with either DPA or SAS. A comparison between these results obtained from two previous groups of 15 patients treated with DPA alone and SAS alone (using the same study design) shows that PMP accelerated the response to therapy by at least six weeks.

Arthritis, Rheumatoid↗
PubMed1984

Effects of low energy laser on wound healing in a porcine model.

Low energy helium neon laser has been suggested as an effective adjuvant in the healing of open wounds. To date, supportive studies have been performed in loose-skinned animals. For such data to be clinically meaningful, it was felt necessary to study this effect in an animal with a dermal structure more closely resembling that of man, the pig. After creating 62 partial thickness wounds on the dorsum of domestic swine, one-half of these were randomized to receive laser treatment. The remainder served as controls. Laser treated wounds received a daily treatment of 15 sec/cm2 at an irradiance of 64 mW/cm2 (energy fluence = .96 J/cm2/day). With these treatment parameters, we could not demonstrate any clinically significant laser induced acceleration of open wound healing.

Animals↗
PubMed1984

Acute effects of argon laser on human atherosclerotic plaque.

Although the laser has been demonstrated to vaporize coronary artery plaque, there is little information about its ability to resect or vaporize the range of plaques present in peripheral vessels. This study attempts to determine the ability of the argon laser to resect all grades of atherosclerotic plaque, the risk of perforation during plaque resection, the effects on surrounding arteries, and the effect of different transmission media (air, saline solution, and blood) on the delivery of laser energy to the vessel. Seventy-five adult human cadaveric aortic specimens with a range of atherosclerosis from grossly normal artery to extensive calcification with ulceration were exposed to variable energy densities (200 to greater than 20,000 J/cm2) within 48 hours of harvesting. Specimens were examined grossly for the visual effects of laser and microscopically after preparation with hematoxylin-eosin, trichrome, and/or Verhoeff's elastin stains. Our results indicate that normal arteries and noncalcified plaques absorb laser energy and are vaporized. As the atherosclerosis becomes more complex with calcification, calcified regions are not vaporized and cannot be resected. In normal arteries and noncalcified plaque, perforation times were less than 5 seconds. Where palpable calcification was present in atherosclerotic lesions, average perforation time was doubled. In some vessels areas of calcification prevented wall perforation, but areas of subintimal hemorrhage perforated rapidly because of the selective absorption of laser energy by the red color of hemorrhagic tissue. These results remain the same when saline solution is used as a transmission media, although the amount of energy required to achieve the effects is increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Dose requirements of ICI 35,868 (propofol, 'Diprivan') in a new formulation for induction of anaesthesia.

In order to avoid Cremophor-related reactions and reduce the incidence of pain on injection, diisopropylphenol (ICI 35,868; propofol) has been reformulated as an emulsion. One hundred and fifteen patients received an induction dose of propofol in the new formulation. The dose required to induce anaesthesia in 95% of healthy, unpremedicated patients was 2.5 mg/kg. Induction was associated with a degree of cardiovascular and respiratory depression. There were no adverse reactions although there were a number of minor side-effects. The incidence of pain on injection was low (3%) and the overall quality of induction was assessed as good or adequate in 92% of patients.

Adolescent↗
PubMed1984

An assessment of the Humphrey ADE anaesthetic system in the Mapleson A mode during spontaneous ventilation.

The Humphrey ADE anaesthetic breathing system in the Mapleson A mode has been compared with the Magill system in spontaneously breathing conscious volunteers and anaesthetised patients. In the latter, rebreathing occurred at a significantly lower fresh gas flow with the ADE system than when the Magill system was used (mean 45.6 ml/kg/minute and 56.5 ml/kg/minute respectively). There was no significant difference between the fresh gas flow at which rebreathing occurred in conscious volunteers.

Adult↗
PubMed1984

Intracoronary thrombolysis in patients with acute myocardial infarction: comparison of the efficacy of urokinase with streptokinase.

The efficacy of intracoronary urokinase and streptokinase were compared in 80 patients with acute myocardial infarction in a prospective, randomized, double-blind study. Urokinase was infused into the occluded coronary artery at 6000 U/min, and streptokinase was infused at 2000 U/min. Maximal duration of infusion was 2 hr. The frequency of successfully opening the artery was similar for patients receiving urokinase (27 of 45, 60%) and those receiving streptokinase (20 of 35, 57%). Fibrinogen levels after infusion were measured in 63 patients. Nineteen of 29 streptokinase recipients had fibrinogen levels less than 100 mg/dl compared with levels of two of 34 urokinase recipients (p less than .001). Five of 45 (11%) patients receiving urokinase and 10 of 35 receiving streptokinase (29%) had bleeding complications (p less than .05). Major bleeding after early coronary artery bypass surgery was more frequent in the streptokinase group (four of five compared with a similar group of patients receiving urokinase (none of five). This study demonstrates that while urokinase and streptokinase have equal intracoronary thrombolytic efficacy, patients receiving urokinase have less systemic fibrinolysis and less perioperative bleeding with early surgery than do patients receiving streptokinase.

Adult↗
PubMed1983

Chemical inactivation of hepatitis B virus: the effect of disinfectants on virus-associated DNA polymerase activity, morphology and infectivity.

The inactivation of hepatitis B virus (HBV) using two commercially available disinfectants was analysed. Indirect evidence of virus inactivation was obtained by examining the decrease in HBV-associated DNA polymerase and HBcAg activities after treatment with increasing concentrations of disinfectant. Inactivation was accompanied by the irreversible loss of all morphological forms typically found in hepatitis B-positive sera and in particular 42-nm HBV particles were absent. Physiochemical analysis confirmed that the exposure of HBV to either product resulted in the degradation of virus particle structure. Direct evidence of HBV inactivation was obtained by treatment of virus pellets prior to inoculation into susceptible chimpanzees. No evidence of hepatitis B was found in animals receiving treated HBV thereby confirming the suitability of certain disinfectants for the inactivation of potentially infectious material.

1-Propanol↗
PubMed1983

The use of the argon laser in the treatment of experimental endometriosis.

The argon laser offers several theoretical advantages over excision, electrocautery, or CO2 laser therapy for the treatment of peritoneal implants of endometriosis. Therefore, a study of the feasibility of the argon laser for the treatment of endometriosis was performed using five virgin New Zealand White rabbits. Following 6 days of estrogen administration, each animal underwent laparotomy with excision of the right uterine horn. Sections of endometrium were sutured to several peritoneal surfaces. Approximately 3 weeks later the endometrial implants were photocoagulated with the argon laser (488 nm, 2 W, 2-mm spot size, 3 to 5 seconds). Histologic examination of the sites of laser therapy demonstrated complete ablation of the endometriosis with 0.25-mm damage to the underlying tissue and surrounding tissue.

Animals↗
PubMed1983

Photocoagulation of endometriosis by the argon laser through the laparoscope.

Photocoagulation of peritoneal implants of endometriosis was performed in five women during laparoscopy to evaluate infertility. A 600-microns flexible quartz fiber was passed into the abdomen through a suprapubic incision using an instrument with a steerable operating tip. Thirty-one implants of the uterosacral ligaments, ovaries, fallopian tubes, bladder, and sigmoid were photocoagulated without complication or perforation. Because of the selective absorption of the argon laser by the hemoglobin of the endometriosis implants and the ease of photocoagulating implants at laparoscopy, this technique may eventually be an important therapeutic modality for the treatment of endometriosis.

Adult↗