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Biomedical subjects

D Cameron

Publications and source records attributed to D Cameron.

At least 19 recordsLinked to original sources
PubMed1992

Use of telemetry functions in the assessment of implanted antitachycardia device efficacy.

Twenty patients (aged 50 +/- 21 years and mean left ventricular ejection fraction 37 +/- 17%) with recurrent ventricular arrhythmias were treated with an investigational, implantable combined antitachycardia-pacing cardioverter defibrillator. The device's telemetry capabilities include both stored (1-second snapshots) and real-time display of endocardial and device-circuit signals. The device can store these before, during and after up to 50 tachycardia and antitachycardia pacing episodes. All stored events are indexed to a 24-hour internal clock. During 10.1 +/- 5.1 months of follow-up, the device was used in 11 of 20 patients. In the entire group, antitachycardia pacing was activated on 44 +/- 14 occasions per patient (total 874) and shock delivery occurred on 8 +/- 14 occasions per patient (total 156). Reconstruction by stored telemetry of all device-therapy episodes was possible. Twenty-six percent of all shocks delivered were not appropriate and were due to atrial arrhythmias in 2 patients and dysfunction of the sensing lead in 3. The absence of a relation between symptoms and appropriate shock delivery was documented in 1 patient. Antitachycardia pace acceleration occurred in 5.3% of cases; 7% of attempts at pacing were unsuccessful and needed shock therapy. It is concluded that the enhanced telemetry available in newer antitachycardia devices enables more accurate assessment of device use and enhances diagnosis of inappropriate therapy delivery.

Electric Countershock↗
PubMed1992

Farm accidents in children.

OBJECTIVE: To examine the problem of accidental injury to children on farms. DESIGN: Prospective county based study of children presenting to accident and emergency departments over 12 months with injuries sustained in a farm setting and nationwide review of fatal childhood farm accidents over the four years April 1986 to March 1990. SETTING: Accident and emergency departments in Aberystwyth, Carmarthen, Haverfordwest, and Llanelli and fatal accidents in England, Scotland, and Wales notified to the Health and Safety Executive register. SUBJECTS: Children aged under 16. MAIN OUTCOME MEASURE: Death or injury after farm related accidents. RESULTS: 65 accidents were recorded, including 18 fractures. Nine accidents necessitated admission to hospital for a mean of two (range one to four) days. 13 incidents were related to tractors and other machinery; 24 were due to falls. None of these incidents were reported under the statutory notification scheme. 33 deaths were notified, eight related to tractors and allied machinery and 10 related to falling objects. CONCLUSIONS: Although safety is improving, the farm remains a dangerous environment for children. Enforcement of existing safety legislation with significant penalties and targeting of safety education will help reduce accident rates further.

Accidents↗
PubMed1992

Homocysteine-induced alterations in extracellular amino acids in rat hippocampus.

The effects of DL-homocysteine, and DL-homocysteate, on extracellular levels of amino acids in the rat hippocampus have been studied using brain microdialysis. Hippocampal electroencephalogram activity was monitored simultaneously using an electrode attached to the dialysis probe. DL-Homocysteine (1200 mg/kg; i.p. injection) produced epileptic activity in hippocampus in an inconsistent manner. Alterations in electroencephalogram activity were not observed in urethane anaesthetized animals, whereas 50% of Hypnorm anaesthetized animals exhibited epileptic activity. DL-Homocysteate (2 mu mol; i.c.v.) induced epileptic activity in a majority of animals anaesthetized using urethane. Dialysate levels of aspartate were significantly elevated by homocysteine in both groups of animals. Conversely, dialysis levels of GABA were reduced. Dialysate levels of other amino acids measured (glutamate, glutamine, taurine, alanine and valine) were not affected significantly. Dialysate levels of taurine were increased significantly in animals injected with homocysteate. These data suggest that the imbalance in excitatory:inhibitory neurotransmission in the hippocampus caused by these alterations in extracellular levels of neuroexcitatory (i.e. aspartate) and neuroinhibitory (i.e. GABA) transmitters could underly the epileptic effect of homocysteine.

Amino Acids↗
PubMed1992

Selective embolisation of intrahepatic aneurysms.

The radiological techniques that can be used to selectively embolise small arteries have improved markedly in the past few years. This article discusses the use of transcatheter embolisation in the management of three patients with aneurysms involving the intrahepatic arterial tree.

Adult↗
PubMed1992

Double blind, controlled trial of 4-aminosalicylic acid and prednisolone enemas in distal ulcerative colitis.

Corticosteroid or 5-aminosalicylic acid enemas are the treatment of choice for distal ulcerative colitis but up to one third of patients may be unresponsive. As an alternative therapy might be advantageous, the efficacy of six weeks' treatment with 2 g 4-aminosalicylic acid (4-ASA) (n = 24) and 20 mg prednisolone enemas (n = 21) were compared in a double blind, randomised trial in patients with acute distal (less than 30 cm from the anus) ulcerative colitis. Baseline demography and clinical severity were similar in both groups. Five of 24 patients receiving 4-ASA and 4 of 21 receiving prednisolone did not complete the trial because of deteriorating symptoms, failure to improve, or side effects. At the time of leaving the trial, 24 hour stool frequency, the presence of blood in the stools, and histological and sigmoidoscopic appearances were similar in both groups. Symptomatic improvement occurred in 17 of 24 patients receiving 4-ASA compared with 11 of 21 receiving prednisolone (chi 2 = 1.62, NS). Complete symptomatic improvement occurred in 9 of 24 patients receiving 4-ASA compared with 5 of 21 receiving prednisolone (chi 2 = 0.98, NS). Histological improvement was seen in 9 of 24 patients on 4-ASA compared with 7 of 21 on prednisolone (chi 2 = 0.08, NS). One patient receiving 4-ASA was considered to have an idiosyncratic reaction to the drug but other side effects were not considered to be drug related. Thus, 4-ASA, previously used in the treatment of tuberculosis (para-aminosalicyclic acid), is as good as prednisolone in the treatment of distal ulcerative colitis and should be considered in patients unresponsive to steroids or in whom steroid treatment is undesirable.

Aminosalicylic Acid↗
PubMed1991

Aerosol delivery in neonatal ventilator circuits: a rabbit lung model.

The benefits of inhaled therapy in ventilated neonates are recognized, but the reliability of drug delivery in nebulizer-ventilator circuits is uncertain. We quantified the effect of changing variables. Twenty-three freshly killed rabbits (1.15-1.9 kg) were ventilated via a tracheostomy by a pressure-limited, time-cycled ventilator (Neovent). A radioaerosol of 99Tcm pertechnetate from an Ultravent nebulizer (Mallinkrodt) was fed into the proximal ventilator tubing. Two 3-minute nebulizations at "standard settings" were followed by 2 at altered pressure, frequency, gas flow, I:E ratio, or position of the nebulizer in the circuit. Each nebulization was followed by a 3-minute gamma camera image and total deposited radioactivity was measured in excised lungs and trachea. Images demonstrated good peripheral aerosol deposition. At standard settings, lung deposition averaged 2.8% of the aerosol released. This was decreased markedly by reducing tidal volume (ventilator pressures) and residence time of aerosol (I:E ratio). Reduced gas flow decreased deposition slightly, presumably by increased particle size and marginally reduced tidal volume. Deposition did not change with increased frequency; increased minute ventilation was offset by decreased residence time of the aerosol. We conclude that the Ultravent nebulizer can be used to nebulize drugs in a standard neonatal circuit, although the dose delivered is small. Tidal volume and aerosol residence time are important determinants of aerosol delivery.

Animals↗
PubMed1991

Short report: plasma somatostatin concentrations in the irritable bowel syndrome.

The description of a patient with the irritable bowel syndrome whose symptoms were completely relieved by the administration of somatostatin raised the possibility that a deficiency of somatostatin may be involved in the pathogenesis of the disorder. We have examined this possibility by studying 11 healthy controls (35 +/- 12 years; mean +/- S.D. 8 female) and 10 irritable bowel syndrome patients (39 +/- 14 years; 7 female) complaining of frequency of defaecation of 4 or more times a day. Plasma somatostatin concentrations were determined by specific radioimmunoassay, fasting and at 15, 30, 45, 60, 90, 120 and 180 min after a standard breakfast. Irritable bowel syndrome patients and controls had similar fasting (27.4 +/- 5.1 vs. 35.2 +/- 4.3 pg/ml; mean +/- S.E.M. and integrated increment of post-prandial (5105 +/- 858 vs. 3885 +/- 793 pg.min/L) plasma concentrations of somatostatin, as assessed by student's t-test. These observations do not support the idea that a state of somatostatin deficiency exists in the irritable bowel syndrome.

Adult↗
PubMed1991

A mattress suitable for use with tilting tables in a radiology department.

It has been possible to design a comfortable, yet highly practical mattress for use in general purpose screening rooms with tilt tables. Attention has been paid to materials and fittings and because it is easy for the staff to use it is in constant use. It has become an essential part of our equipment and has considerably improved the comfort of many procedures.

Beds↗
PubMed1990

The effects of ingestion time of gliclazide in relationship to meals on plasma glucose, insulin and C-peptide levels.

The effect of altering the timing of gliclazide administration in relation to a meal was studied in ten type 2 (non-insulin dependent) chronically treated diabetics. Gliclazide was given 30 min before, at the start of and 30 min after breakfast or omitted altogether. Plasma gliclazide was present at greater than 2 mg/l throughout the study periods. Administration at 30 min after the meal significantly delayed the time to peak for plasma gliclazide. No significant difference was noted in plasma glucose, insulin or c-peptide patterns with any protocol. It is concluded that, in clinical practice, with chronically treated diabetics the timing of gliclazide ingestion in relation to meals is not critical.

Aged↗
PubMed1990

Evaluation of nebulizers for use in neonatal ventilator circuits.

The use of nebulizers in neonatal ventilator circuits offers a new and relatively uncharted route of therapy for infants in respiratory failure. We used a model lung to investigate and compare different nebulizer types and therapeutic agents and to make practical observations. Five different nebulizers (Ultravent, Acorn, MAD2, Small Particle Aerosol Generator, and Pulmosonic) were compared for efficiency of delivery of an amino-phylline aerosol to the model lung, and the particle size of aerosol produced by them was measured. A Nebulizer Efficiency Index (NEI) was created, representing the deposition rate of the original solution as aerosol upon the model lung filter. The Acorn (2.8.10(3) ml/min) and MAD2 (2.4.10(-3) scored highest NEI. When a suspension of budesonide was nebulized, minimal amounts of drug were recovered from the filter when the nebulizer producing the smallest particle size (Ultravent) was studied, suggesting that suspensions of drugs behave differently from solutions. Significant changes need to be made to a conventional circuit when jet nebulizers are used; most of these are obviated by the use of an ultrasonic nebulizer, which also avoids the potential problem of marked cooling of the gas flow produced by jet nebulizers.

Aerosols↗