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Biomedical subjects

F Moran

Publications and source records attributed to F Moran.

At least 37 records · Page 2Linked to original sources
PubMed1990

Variation of breath sound and airway caliber induced by histamine challenge.

Inspiratory breath sounds were recorded from the chest wall during histamine challenge in five subjects with mild asthma (baseline FEV1 greater than 60% of predicted normal). The median frequency of the power spectrum of the breath sounds was found to correlate with the percentage change in FEV1 induced by histamine and with FEF50. The analysis suggests that for a decrease in FEV1 of 20%, the median frequency of breath sound would increase by 80 Hz. Variation in airway caliber produced a consistent alteration in the distribution of energy in inspiratory breath sound in the absence of wheeze. Spectral analysis of breath sound may be a useful addition to conventional spirometry in identifying changes in airway diameter.

Adult↗
PubMed1989

Pulmonary abnormalities in Crohn's disease.

Abnormalities of pulmonary function in Crohn's disease have been described, although the results are conflicting and anecdotal accounts of lung involvement are few. In this study we assessed the prevalence of lung function abnormalities in Crohn's disease, and the relative contributions of age, sex, smoking and past medical history, and Crohn's disease activity to the pulmonary abnormalities found. Twenty-nine patients with Crohn's disease and 29 age-, sex- and smoking-matched volunteer controls underwent detailed respiratory assessment. Airways obstruction due to chronic bronchitis and asthma was present in 13 patients with Crohn's disease, but was not more prevalent than in the control group. FEV1 was similar in both Crohn's disease and control subjects (84.2 +/- 21.2% predicted, mean +/- SD; 93.7 +/- 16.3%, respectively: n.s.). The vital capacity was significantly lower in the Crohn's disease patients than in controls (86.7 +/- 16.6%; 95.9 +/- 12.7%; P less than 0.01), but this may have been influenced by the higher prevalence of past or intercurrent medical illnesses affecting the chest in Crohn's disease patients. No patient had evidence of fibrosing alveolitis or bronchiectasis. The haemoglobin corrected transfer factor was significantly lower in the Crohn's disease patients than in controls (100.4 +/- 17.4%; 113.2 +/- 25.1: P less than 0.05) but the diffusing coefficient was not significantly different. There was a significant correlation (r = 0.44, P less than 0.05) between the residual volume and the Crohn's disease activity index but otherwise no close relationship was observed between Crohn's disease activity, extent or duration and the indices of lung function. These findings suggest that the lungs are relatively unaffected by Crohn's disease.

Adult↗
PubMed1988

Management of asthma in hospital: a prospective audit.

In a prospective study of management of asthma in hospital patients with acute asthma admitted to a single hospital over a calendar year were surveyed. Altogether 157 out of 194 admissions (81%) were studied. The patients (16 of whom had been admitted twice and one three times) were interviewed at home about two weeks after discharge, and their hospital records were reviewed. When interviewed an appreciable proportion of patients said that their asthma had been poorly controlled after their discharge from the hospital: 54 reported regular sleep disturbance due to wheeze, 78 tightness of the chest in the morning, and 77 wheeze after climbing one flight of stairs. Patients had been described on admission as having had symptoms of deteriorating asthma for a median of three days. Closer questioning of 71 patients, however, elicited that 50 had had regular symptoms indicating poor control for weeks or months. Most patients did not know how their drugs worked, and many did not have an appropriate plan of action in the event of a further attack. In all the cases studied 114 patients were treated with oral corticosteroids, only 70 had had their previous maintenance treatment increased at the time of discharge, and 107 had a follow up appointment booked for an average of three and a half weeks after discharge. These findings show that undersupervision and undertreatment of patients with asthma are common and not confined to those dying of the condition.

Asthma↗
PubMed1988

Differences in hospital asthma management.

Asthma management was audited prospectively for one year in a large teaching hospital. Full details were available on 77% of all patients admitted, or readmitted, with asthma during that year (150 of 195 admissions). 64 patients were admitted to general wards with a special interest in respiratory medicine, and 86 to general wards without this specialist interest. Cases in the two groups were similar in terms of age, previous severity of asthma, previous treatment, and initial pulse rate. Fewer cases in the non-specialist group were treated with oral corticosteroids (67%, vs 83%), had regular peak flow recordings (42%, vs 73%), or were given return appointments (56%, vs 92%); and fewer had their regular inhaled therapy increased after discharge (28%, vs 55%). At interview 13 days later, more patients from the non-specialist group reported sleep disturbance (41%, vs 23%), morning chest tightness (55%, vs 37%), ow wheeze on 1 flight of stairs (58%, vs 34%). 20% of first admissions in the non-specialist group were readmitted within the year, compared to 2% of the group treated on wards with a specialist interest in respiratory medicine. These data suggest that the intensive management of asthmatic patients, practised in respiratory units, prevents much unnecessary morbidity.

Acute Disease↗
PubMed1988

Dynamics of a biochemical system with multiple oscillatory domains as a clue for multiple modes of neuronal oscillations.

We analyze the behavior of a two-variable biochemical model in conditions where it admits multiple oscillatory domains in parameter space. The model represents an autocatalytic enzyme reaction with input of substrate both from a constant source and from non-linear recycling of product into substrate. This system was previously studied for birhythmicity, i.e. the coexistence between two stable periodic regimes (Moran and Goldbeter 1984), and for multi-threshold excitability (Moran and Goldbeter 1985). When two distinct oscillatory domains obtain as a function of the substrate injection rate, the system is capable of exhibiting two markedly different modes of oscillations for slightly different values of this control parameter. Phase plane analysis shows how the multiplicity of oscillatory domains depends on the parameters that govern the underlying biochemical mechanism of product recycling. We analyze the response of the model to various kinds of transient perturbations and to periodic changes in the substrate input that bring the system through the two ranges of oscillatory behavior. The results provide a qualitative explanation for experimental observations (Jahnsen and Llinas 1984b) related to the occurrence of two different modes of oscillations in thalamic neurones.

Models, Biological↗
PubMed1988

Finding complex oscillatory phenomena in biochemical systems. An empirical approach.

Starting with a model for a product-activated enzymatic reaction proposed for glycolytic oscillations, we show how more complex oscillatory phenomena may develop when the basic model is modified by addition of product recycling into substrate or by coupling in parallel or in series two autocatalytic enzyme reactions. Among the new modes of behavior are the coexistence between two stable types of oscillations (birhythmicity), bursting, and aperiodic oscillations (chaos). On the basis of these results, we outline an empirical method for finding complex oscillatory phenomena in autonomous biochemical systems, not subjected to forcing by a periodic input. This procedure relies on finding in parameter space two domains of instability of the steady state and bringing them close to each other until they merge. Complex phenomena occur in or near the region where the two domains overlap. The method applies to the search for birhythmicity, bursting and chaos in a model for the cAMP signalling system of Dictyostelium discoideum amoebae.

Cyclic AMP↗
PubMed1988

A retrospective survey of asthma management in hospital.

A retrospective survey of asthma admissions to general medical units during 1983 is described. 127 cases occurred, of whom 52 were males (44%). The average age was 45.2 years. Forty-eight per cent were receiving inhaled steroids or cromoglycate before admission and 16% regular oral steroids. Initial assessment seldom included peak flow measurement although these were made subsequently in 57%. No steroids were used in 32% of cases. No oxygen was given in 48% of cases and when used was usually at low flow rates. Apart from a reducing course of steroids, 46% of cases were discharged with no increase in pre-admission maintenance treatment and although follow-up was planned for 76% it was for an average 4.9 weeks later. This survey suggests a tendency to under-treatment and undersupervision of asthma patients admitted to acute general medical wards which may well be a cause of unnecessary morbidity.

Adolescent↗
PubMed1986

A critical appraisal of a rapid radiographic method of determining total lung capacity.

We have demonstrated that the total lung capacities of normal caucasian adults, can be satisfactorily estimated by means of a regression equation derived from a single set of three measurements taken from a specially exposed plain X-ray film of the chest. However, these equations differ from those found by workers who have studied patients with lung disease. It is concluded from this that different regression equations are to be expected for normal and diseased lungs, and that, the appropriate equation will depend not only on the presence of disease, but also on its type and severity. It is also concluded that the rapid radiographic method of estimating total lung capacity can make little contribution to the diagnostic assessment of lung disease. However, the regression equations appropriate to particular ethnic groups could be used to measure TLC in normal subjects rapidly and inexpensively in places where specialised respiratory equipment and trained personnel are lacking.

Adult↗
PubMed1985

Excitability with multiple thresholds. A new mode of dynamic behavior analyzed in a regulated biochemical system.

We analyze in a biochemical model the phenomenon of excitability in which suprathreshold perturbations of a stable steady state are amplified in a pulsatory manner. The two-variable model is that of an autocatalytic enzyme reaction with recycling of product into the substrate. This model was previously studied for the coexistence between two stable periodic regimes (birhythmicity). We show that the multiplicity of dynamic behavioral modes extends to the phenomenon of excitability. Whereas excitable behavior is generally characterized by a single threshold for excitation, two distinct thresholds may coexist in this model. Moreover, in these conditions, two different plateaux are obtained for the response amplitude when the stimulus is gradually increased. By means of phase plane analysis we explain the origin of multiple thresholds for excitability and predict the conditions for their occurrence. Implications of the phenomenon for excitable cells, in particular for neurons, are discussed.

Animals↗
PubMed1984

Reporting of ventilation perfusion images for pulmonary embolism: accuracy and precision.

Thirty-four hospital patients with suspected pulmonary embolism (PE) had ventilation perfusion (VP) imaging after pulmonary angiography to assess the performance of highly specific criteria for diagnosis of PE and to evaluate the precision of image reporting. A diagnostic result was obtained from VP imaging in 21 of 34 patients giving a sensitivity for PE of 80% and a specificity of 100% in this subgroup. Six of 11 patients with PE had an indeterminate study which reduced the overall sensitivity of the technique for PE in the whole group. A critical analysis of image reporting by two readers gave an 85% inter-observer agreement on ranking as diagnostic or indeterminate for PE (k 0.69) and 91%-94% agreement for consensus reproducibility (k 0.82). We conclude that the degree of accuracy and precision of reporting that can be obtained using specific criteria will provide a reliable diagnosis in a significant number of patients suspected of having PE. Consensus reporting by two readers is shown to be more reliable than individual reporting.

Angiography↗
PubMed1984

Pulmonary hypersensitivity in the alginate industry.

Salts of alginic acid are complex polymerised polysaccharides which are chemically extracted from seaweed. Workers in the alginate industry are exposed to dust from dried milled seaweed and pure alginate compounds. In this survey of one of the two factories in Britain producing alginates, we found evidence of pulmonary hypersensitivity to seaweed dust in seven per cent of the total work force, and evidence of precipitating antibody to sodium alginate and seaweed extracts in the serum of 4.5 per cent of the work force. Challenge testing of a number of employees with symptoms showed a dual response with immediate airways obstruction, and a later loss of lung volume, with associated impairment of transfer factor.

Alginates↗
PubMed1984

Alteration in the low frequency lung sounds in respiratory disorders associated with crackles.

Lung sounds were recorded in three groups of 5 subjects, 2 conditions associated with pulmonary crackling (asbestosis and pulmonary oedema), and in normal non-smoking males. A technique was used which permitted extraction and analysis of the low-frequency sounds. Differences were evident in the 5-50 Hz range of the frequency spectra which allowed separation of all 3 groups. A prominent feature was the close similarity of the low-frequency sounds within the asbestos group when plotted on a scattergram. The findings suggest that alteration in low-frequency breath sound occurs in parenchymal lung disease and that its potential merits further investigation.

Asbestosis↗
PubMed1983

Anti-emetic efficacy and toxicity of nabilone, a synthetic cannabinoid, in lung cancer chemotherapy.

Nabilone, a synthetic cannabinoid, and Prochlorperazine were compared in a double-blind crossover study of 34 patients with lung cancer undergoing a 3-day schedule of chemotherapy with Cyclophosphamide, Adriamycin and Etoposide. Symptom scores were significantly better for patients on nabilone for nausea, retching and vomiting (P less than 0.05). Fewer subjects vomited with nabilone (P = 0.05) and the number of vomiting episodes was lower (P less than 0.05); no patients on nabilone required additional parenteral anti-emetic. More patients preferred nabilone for anti-emetic control (P less than 0.005). Adverse effects common with nabilone were drowsiness (57%), postural dizziness (35%) and lightheadedness (18%). Euphoria was seen in 14% and a "high" in 7%. Erect systolic blood pressure was lower in nabilone patients on Day 1 (P = 0.05) but postural hypotension was a major problem in only 7%. Nabilone is an effective oral anti-emetic drug for moderately toxic chemotherapy, but the range and unpredictability of its side-effects warrant caution in its use.

Adult↗