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Biomedical subjects

D Royston

Publications and source records attributed to D Royston.

At least 127 records · Page 7Linked to original sources
PubMed1984

A simple separator to generate half micron aqueous particles for lung imaging.

An aerosol of a radionuclide may be used for ventilation imaging as an alternative to radioactive rare gases. For good-quality images as few particles as possible must be deposited in the trachea and bronchi, which means that no, or very few, particles should have aerodynamic diameter of more than 2 micron. We have developed a separator to modify the output of an Acorn jet nebuliser. It reduced the proportion of particles in the aerosol with aerodynamic diameters of more than 2 micron from 60% for the unmodified output of the nebuliser to only 6%; it consisted of a cylinder of perspex with two compartments containing inert spheres, either stainless steel or glass, of diameter 3 mm (the first compartment contained two layers of spheres, and the main section was packed with spheres). To examine the efficiency of the separator system for routine clinical use we compared the images produced and the deposition of the particles in the modified aerosol (using 99TcmDTPA) with the distribution of ventilation of 81Krm in eight subjects. Despite the theoretical differences between the behaviour of a gas molecule and of a particle in the respiratory tree, the images produced using the modified aerosol delivery system were as good as those produced with 81Krm in normal subjects. In abnormal subjects the images produced were only distinguished following the calculation of a penetration index.

Adult↗
PubMed1984

The effect of nicotine on pulmonary epithelial permeability in man.

We examined the effect of nicotine on pulmonary epithelial permeability in man. Nicotine was administered from a chewing gum base given over a seven-day period. An index of pulmonary permeability was derived from the rate of clearance from the lung into the blood of 99mTcDTPA (diethylenetriamine pentacetate). In five nonsmoking volunteers there was no change in permeability for the seven-day study period. This lack of effect of nicotine alone was in striking contrast to the increase in epithelial permeability observed in five nonsmoking subjects who took up cigarette smoking.

Adult↗
PubMed1983

Effect of subanaesthetic concentrations of nitrous oxide on the regulation of ventilation in man.

The pattern of ventilation was studied in eight healthy male volunteers breathing, in sequence, air and then two subanaesthetic concentrations of nitrous oxide (20% and 40%). The effect of these gas mixtures on the response to an added inspiratory resistance (3.88 kPa litre-1s-1) was examined. During unrestricted breathing of 40% nitrous oxide, there was a significant decrease (P less than 0.05) in inspiratory time (TI), a concomitant increase in the rate of ventilation and a significant decrease (P less than 0.05) in the end-tidal carbon dioxide tension (PE'CO2) compared with air breathing. For the first breath on load while breathing 40% nitrous oxide, there were significant decreases (P less than 0.05) in the responses for TI and tidal volume (VT) compared with the responses when breathing air. TI, VT, minute volume and PE'CO2 were similar for each gas mixture during steady state breathing against resistance. The increase in PE'CO2 when breathing 40% nitrous oxide against the resistance represented a significant (P less than 0.01) difference in response to the load compared with that breathing air. There was no significant change in these variables when breathing 20% nitrous oxide.

Adult↗
PubMed1983

Enflurane anaesthesia causes graded changes in the brainstem and early cortical auditory evoked response in man.

The effect of increasing end-tidal enflurane concentration on the auditory evoked response was studied in six patients. After a standard induction, anesthesia was maintained with 70% nitrous oxide in oxygen and the end-tidal enflurane concentration was increased gradually from 0 to 1% over a period of 30 min. The averaged auditory evoked response was derived from the electroencephalogram and measurements were made of the latencies and amplitudes of waves I, III, V, Pa and Nb within the auditory evoked response. The latencies of all waves and the interpeak latencies I to V and III to V showed significant linear increases and the amplitudes of Pa and Nb showed significant linear decreases with increasing end-tidal enflurane concentration. These results could not be explained by changes in deep body temperature or end-tidal carbon dioxide concentration. The study demonstrated a dose-related direct effect of enflurane on the brainstem and early cortical components of the auditory evoked response.

Adolescent↗
PubMed1983

Disseminated arterial calcification associated with acardius acephalus.

Widespread arterial calcification was shown at necropsy in an infant who died at age 5 days and whose twin was acardiac. The changes resembled closely those described in idiopathic arterial calcification of infancy and the possible importance of haemodynamic factors in the production of these changes is discussed.

Abnormalities, Multiple↗
PubMed1983

Carboxyhaemoglobin and pulmonary epithelial permeability in man.

The effect of cigarette smoke exposure on pulmonary epithelial permeability was studied in 45 smokers and 22 non-smokers. An index of cigarette smoke exposure was obtained from the carboxyhaemoglobin concentration (HbCO%). Pulmonary epithelial permeability was proportional to the half-time clearance rate of technetium-99m-labelled diethylene triamine pentacetate (99mTc DTPA) from lung to blood (T1/2LB). The relationship between T1/2LB and HbCO% was hyperbolic in form and the data could be fitted to the quadratic formula (formula; see text) where the parameters a0, a1, and a2 represent respectively the asymptotic T1/2LB value at large carboxyhaemoglobin values and the slope and shape of the curve. The values of these parameters were a0 4.4 (2.6), a1 = 77.8 (15.5), and a2 -25.5 (9.7) (SE). This is the first demonstration of a dose-response relationship between carboxyhaemoglobin and an increased permeability of the lungs in man and provides a technique for identifying the roles of carbon monoxide and other cigarette smoke constituents in causing increased pulmonary epithelial permeability.

Adult↗
PubMed1983

Abnormality of an index of alveolar-capillary barrier permeability associated with respiratory tract infection in the rat.

The study investigated the role of subclinical respiratory tract infection in producing an abnormality of lung function assessed by measuring an index of the permeability of the blood-gas barrier to 99mTcDTPA. Pasteurella pneumotropica was grown from throat swabs taken from 9 female rats age 10 weeks at the time of the experiment and housed under conventional husbandry conditions for 4 weeks previously. There was a significant association between the amount of bacteriological growth and an abnormality of the index of permeability. In contrast to this finding, there was no bacterial growth and no abnormality of function found in 12 female rats age 6 weeks, kept under strict barrier-maintained conditions. This finding emphasises the need for great care to be taken in the husbandry of animals used in scientific research.

Animals↗
PubMed1982

Serum methionine and hepatic enzyme activity in anaesthetists exposed to nitrous oxide.

Normal serum concentrations of methionine, leucine, isoleucine and valine have been found in 10 anaesthetists using nitrous oxide under their regular working conditions without scavenging of patients' exhaled gas. Mean inhaled concentrations of nitrous oxide ranged from 150 to 400 p.p.m. The results indicate either that there was no significant inhibition of methionine synthase (attributable to oxidation of vitamin B12 by nitrous oxide) or that methionine concentrations were maintained by dietary intake or by the alternative betaine pathway of methylation of homocysteine. In either case, anaesthetists working under these conditions should not be at risk from reduced methionine concentrations. We also report normal serum activities of aspartate transaminase and gamma glutamyl transpeptidase.

Adult↗
PubMed1982

Pulmonary epithelial permeability is immediately increased after embolisation with oleic acid but not with neutral fat.

Pulmonary fat embolism occurs frequently after trauma but its functional significance is often unclear. To obtain direct evidence of lung damage caused by fat embolism we have measured changes in permeability of the alveolar-capillary interface. A permeability index was derived from the half time clearance from lung to blood (T1/2LB) of 99mTcDTPA introduced into the lung in a 1 ml bolus. Three groups of rabbits were studied. Baseline T1/2LB. did not differ significantly between groups. After intravenous injection of saline placebo in one group and of 300 mg/kg triolein in another group there was no change in permeability index. After intravenous injection of 100 mg/kg oleic acid in the third group there was an immediate change in T1/2LB from a monoexponential baseline 280 +/- 20 min (SEM) to a multiexponential curve which was resolved into two components, one with a T1/2LB of 3.2 +/- 0.6 min (SEM) and the other 39.5 +/- 7.6 min (SEM). Statistically significant changes in alveolar-arterial PO2 difference, dynamic compliance, chest radiography, and postmortem lung water accompanied the changes in T1/2LB in this group. There were no significant changes in these variables in the placebo or triolein group. Histological studies of the lung tissue of these animals using the osmic acid stain for fat showed no fat in the placebo group, extensive fat embolisation which was densely stained in the triolein group and much less densely stained fat in the oleic acid group. Measurement of the permeability of the alveolar-capillary interface provides direct evidence of lung damage after oleic acid embolisation. There were no functional changes in animals with extensive embolisation with triolein.

Animals↗
PubMed1981

Comparison of respiratory characteristics during enflurane and halothane anaesthesia.

The effects of enflurane on certain respiratory characteristics were compared with those of halothane in 70 patients during anaesthesia with spontaneous breathing using a specially designed circuit. The rate of respiration with enflurane (mean 22 b.p.m.) was slower than with halothane (mean 31 b.p.m.; P less than 0.001) and the tidal volume greater (enflurane mean 240 ml, halothane 180 ml; P less than 0.05). There was no statistically significant difference in the minute volume of ventilation or end-tidal carbon dioxide concentration between the two agents. The effects of a narcotic premedication were observed in 16 patients in the study. The main effect was to produce slowing of respiratory rate (enflurane mean 16 b.p.m.; halothane 18 b.p.m.). The value of the respiratory pattern compared with the measurement of heart rate and arterial pressure as a clinical guide during anaesthesia is discussed.

Adolescent↗
PubMed1979

Simultaneous disseminated aspergillosis and zygomycosis in a leukemic patient.

Although the incidence of fungal infections is increasing, infections caused by more than one fungus are rare. We have described the clinical, pathologic, and mycologic findings in a leukemic patient with simultaneous pulmonary infection and systemic dissemination caused by Aspergillus fumigatus and Rhizopus sp.

Adult↗
PubMed1978

True anaphylaxis to suxamethonium chloride. A case report.

A severe anaphylactic reaction to suxamethonium chloride is reported. The patient had received suxamethonium uneventfully on four previous occasions. Previous sensitization and immunological studies indicated that this was a classical type I hypersensitivity reaction.

Adult↗
PubMedDate not supplied

Cutaneous lesions, not just skin deep!

BACKGROUND: Cutaneous metastatic disease is not unusual but it may mimic inflammatory lesions. The growth pattern of skin metastases is unpredictable and may differ from that of the primary tumour. Skin metastases may present as rapidly growing, solitary sessile or polypoid vascular nodules that ulcerate or bleed. AIM: To investigate the presenting complaints, surgical treatment and outcome of patients with cutaneous metastatic disease. METHODS: We present three cases of metastatic skin cancer recently seen in our Department and review the clinical and pathological findings. RESULTS: The finding of metastatic skin cancer is associated with a very poor prognosis and suggests widespread disease dissemination. CONCLUSION: The paper emphasizes the importance of excisional biopsy and accurate tissue diagnosis of skin nodules.

Adenocarcinoma↗
PubMedDate not supplied

Pulmonary angiography and embolization for severe hemoptysis due to cavitary pulmonary tuberculosis.

PURPOSE: To identify the role of pulmonary angiography in the diagnosis and treatment of severe hemoptysis due to cavitary pulmonary tuberculosis. METHODS: Selective pulmonary angiography was performed on eight patients with severe hemoptysis uncontrolled by previous bronchial and systemic arterial embolization. RESULTS: Three (38%) patients had Rasmussen aneurysms, which were successfully embolized with steel coils. Five patients demonstrated pulmonary arterial hypoperfusion in the diseased lung. CONCLUSIONS: We recommend pulmonary angiography in cavitary tuberculous patients with severe hemoptysis who do not respond to systemic arterial embolization. Rasmussen aneurysms are effectively treated by steel coil occlusion.

Adult↗
PubMedDate not supplied

The serine antiprotease aprotinin (Trasylol): a novel approach to reducing postoperative bleeding.

Aprotinin is a polypeptide from bovine lung which has been known since 1930, and which has previously been administered to humans as a relatively non-specific protease inhibitor in a number of disease states. In 1987, a remarkable use for this drug was realized, when by chance, it was discovered that by infusing large doses of aprotinin during cardiac surgery, it was possible to greatly reduce the bleeding which had hitherto been regarded as normal in such operations. The aim of this article is to briefly review the biochemistry and pharmacology of aprotinin, and to describe the background to its use in preventing postoperative bleeding. The use of aprotinin in reducing bleeding after cardiac surgery is then described in detail, and outlined for other types of major surgery. The possible modes of action of aprotinin in reducing bleeding are discussed, with particular reference to the bleeding which follows cardiac surgery. The profound effect of aprotinin, given in a novel dosage to reverse the postoperative haemostatic defect suggests that this drug may abolish the need for blood transfusions in most patients after major surgery. In addition, it is clear that aprotinin will provide a potent tool to probe some of the remaining mysteries of the haemostatic process.

Aprotinin↗