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Biomedical subjects

T C Aitchison

Publications and source records attributed to T C Aitchison.

At least 37 records · Page 2Linked to original sources
PubMed1997

Clinical trial of a mucin-containing oral spray for treatment of xerostomia in hospice patients.

Thirty-five hospice patients complaining of dry mouth entered a double-blind, single-phase placebo-controlled trial of a mucin-containing oral spray (Saliva Orthana) for the relief of xerostomia. The sprays were administered ad libitum for two weeks by the patients themselves, with nursing help as necessary. A detailed history and examination were undertaken, together with collection of microbiological specimens, at entry and after seven and 14 days of spray usage, respectively. Thirty-one patients were available for follow-up at seven days and 26 patients after 14 days. Relief of oral dryness during the day was reported by 9/15 patients on Saliva Orthana and 10/16 patients on placebo by day 7, with a similar degree of improvement maintained to day 14. The corresponding figures by day 7 for relief of dryness at night were 8/15 for Saliva Orthana and 8/16 for placebo. There were no statistically significant differences between those on active and those on placebo spray for any of the oral symptoms recorded. Neither spray had any major impact on the oral microflora. However, the majority of patients in both treatment groups wished to continue using a mouth spray at the end of their involvement in the trial. Whilst the data from this study provide no evidence for increased benefit of a mucin-containing spray over a mucin-free placebo among xerostomic hospice patients, it is clear that both sprays provided worthwhile symptomatic relief of oral dryness for many of the participants.

Aerosols↗
PubMed1996

Techniques for improving overall consistency of serial ECG analysis.

The techniques that improve the overall repeatability of computer interpretation of electrocardiograms (ECGs) that have been recorded several minutes apart from patients in a clinically stable condition are described. Estimates of the normal amounts of variability present in many ECG parameters that are used in the identification of a variety of cardiac abnormalities have been adopted in conjunction with smoothing techniques to form the basis of the new methodology. When applied to the Glasgow ECG analysis program, these new methods improve overall repeatability by about 31% when tested on a set of 263 pairs of ECGs. Randomly generated noise was added to the test set and an additional technique aimed at removing noise from the ECG tracings was used in conjunction with the smoothing methods. The observed improvement over the original repeatability was 63%.

Adult↗
PubMed1996

Comparison between lentigo maligna melanoma and other histogenetic types of malignant melanoma of the head and neck. Scottish Melanoma Group.

A study of 953 invasive cutaneous malignant melanomas of the head and neck was performed to determine differences between lentigo maligna melanoma and other histogenetic types with regard to patients and sites affected; prognosis was analysed in 595 of these cases. The cases studied comprised all head and neck melanomas registered with the Scottish Melanoma Group between 1979 and 1992, apart from the 3% of cases that were unclassifiable or rare histogenetic types. The histogenetic types of melanoma were 498 (52%) lentigo maligna melanoma (LMM), 237 (25%) superficial spreading melanoma (SSM) and 218 (23%) nodular melanoma (NM). All types increased in incidence throughout the study period. Patients with LMM (mean age 73 years) and NM (mean 68 years) were significantly older than those with SSM (mean 57 years). There were significant anatomical subsite differences related to sex of patients and histogenetic type of melanoma; melanomas on the face were more frequent in females and 90% of LMM occurred at this site, whereas melanomas on the scalp, neck and ears were more frequent in men. Kaplan-Meier estimates of the probability of survival were produced for the 595 of these 953 patients with 5 year follow-up details. In this group of patients the prognostic significance of tumour thickness, Clark level of invasion, ulceration, histogenetic type of melanoma and number of mitoses were studied using stepwise variable selection of procedures. Each of these possible prognostic factors attained individual significance but the tumour thickness was the dominant risk factor in the proportional hazards analysis. When patients were divided into four sex/ulceration subgroups (male/ulcerated, female/ulcerated, male/non-ulcerated, female/non-ulcerated) and analysed by proportional hazards analysis, no variable other than the tumour thickness had any further prognostic effect. Histogenetic type did not remain an independent prognostic variable at this stage. Despite sex and subsite differences, the prognosis for invasive lentigo maligna melanoma does not differ from that for other histogenetic types after controlling for tumour thickness.

Adolescent↗
PubMed1996

Survival analysis: the importance of censored observations.

We have considered the issue of predicting from diagnosis of a condition such as malignant melanoma survival past an often arbitrarily chosen fixed time-point, such as 5 years. Prediction of survival past any time-point becomes rather complicated due to the presence of 'censored observations', and these observations are often ignored in any analysis. Censored observations are subjects who either die of causes other than the disease of interest or are lost to follow-up. The aim of this paper is to show that the result of ignoring these 'censored observations' is an underestimation of the probability of survival beyond the fixed time-point. Ignoring these censored observations results in potentially valuable information on survival being thrown away. This underestimation will often prove to be of considerable magnitude and dependent on the proportion of censored observations present in the data. It is therefore essential to carry out a full actuarial survival analysis which will incorporate all the information contained in these censored observations.

Bias↗
PubMed1996

The effect of climatic heat stress on intermittent supramaximal running performance in humans.

The purpose of this study was to test the hypothesis that intermittent supramaximal running would be negatively affected when performed in a hot humid environment. Twelve physically active, male volunteers took part in this study. The exercise model was performed under three environmental trial conditions, randomly assigned and separated by 1 week. This included performing: (a) a standardized warm-up in the cool environment and a repeated sprint test in the cool environment (CC); (b) a standardized warm-up in the cool environment and a repeated sprint test in a hot, humid environment (CH); and (c) a standardized warm-up in a hot, humid environment and a repeated sprint test in a hot, humid environment (HH). The repeated sprint test involved 20 s runs, each at increasing-intensity, with 100s passive recovery between successive sprints. Capillary blood samples were taken post-warm-up and at 1, 3 and 6 min post-repeated sprint test for the determination of plasma lactate, ammonia and glucose concentrations and the percentage change in plasma volume. Rectal, aural and mean skin temperature were measured continuously throughout each trial condition. Sweat loss was estimated from the change in body mass. Sweat loss was significantly greater in the HH trial than in the CH trial and in the CH trial than in the CC trial (P < 0.0001). Performance was significantly better in the CC trial than in the CH and HH trials (CC vs. CH and HH: 151 +/- 4 vs. 144 +/- 5 and 140 +/- 5 s, respectively, P = 0.02). For the post-exercise data, significant differences were found between the CC and the CH and HH trials in rectal (P = 0.007), aural (P < 0.001) and mean skin temperatures (P < 0.001). No significant differences were found in post-repeated sprint test lactate and ammonia concentrations, or in plasma volume among trial conditions, but glucose concentrations were higher in the CH and HH trials than in the CC trial (P = 0.005). No significant differences were found in performance, body temperature or any blood measurement between the CH and HH trials. Intermittent supramaximal running performance was detrimentally affected by a hot, humid environment, resulting in performance being significantly less in the CH and HH trials than in the CC trial.

Adult↗
PubMed1995

Prognostic trees to aid prognosis in patients with cutaneous malignant melanoma. Scottish Melanoma Group.

OBJECTIVES: To design user friendly guides to prognosis for patients who have had invasive primary cutaneous malignant melanomas surgically excised. DESIGN: Adaptation of the classification tree method was used to derive prognostic trees for four different subgroups of malignant melanoma patients in whom known and possible prognostic variables interacted in different ways. SETTING: Scotland. SUBJECTS: Statistical modelling for prognostic trees was based on 1978 patients whose primary malignant melanoma was first diagnosed in 1979-86 for whom five year follow up and all relevant clinical pathological data were available. The resultant model was validated with 300 patients first diagnosed in 1987 for whom the same information was available. MAIN OUTCOME MEASURES: Actual and predicted rate of survival after diagnosis of primary cutaneous malignant melanoma. RESULTS: The four subgroups of patients were men and women with ulcerated and non-ulcerated cutaneous primary melanomas. Validation of the model showed excellent agreement between actual status of patients in the relevant subgroups and their status as predicted by the model. CONCLUSIONS: The prognostic trees are simple to use and give more accurate prognosis for individual patients than is currently available from tumour thickness alone.

Decision Trees↗
PubMed1995

Measured bronchodilator use in preschool children with asthma.

OBJECTIVE: To investigate how parents use bronchodilator treatment for relief of symptoms when treating their asthmatic preschool children. DESIGN: A commercial electromechanical timer device was attached to a large volume spacer to record the time and date of each use of inhaled bronchodilator over two months. The recorded time and dates were compared with symptoms noted in an asthma diary card. SETTING: Large paediatric teaching hospital in Glasgow. SUBJECTS: 29 preschool children with moderately severe asthma attending a specialist paediatric asthma clinic. MAIN OUTCOME MEASURES: Inhaler use measured by the timer device; symptoms and inhaler use recorded by parents in a daily asthma diary. RESULTS: Satisfactory data were obtained in 22 of the 29 children; the median number of study days was 53 (range 18-77). Asthmatic symptoms were recorded on a median of 30 (3-77) days. Bronchodilator was used on a median of 19 (2-73) days, or on 63% (7-100%) of days when symptoms occurred. The median number of puffs used in a day was 1 (range 0-100) and was significantly related to symptom severity in only 14 of the 22 children. In only two of the 22 children was bronchodilator given more frequently than four hourly, and only five children ever used more than 12 puffs a day. CONCLUSIONS: The frequency of parental administration of bronchodilator treatment was variable and not closely related to the parent's record of symptom severity. Parents often recorded symptoms in their children but did not treat them.

Asthma↗
PubMed1995

Compliance with inhaled asthma medication in preschool children.

BACKGROUND: Previous studies have shown poor compliance with regular drug therapy in children and adults with asthma. In preschool children the parents supervise and are responsible for drug administration, but little is known of compliance in this group. In addition, there are few data on the patterns of drug use of inhaled prophylactic asthma therapy or of the relation between compliance and symptom control. A study was undertaken to address these issues with the hypothesis that parental supervision would result in good compliance. METHODS: The subjects were 29 asthmatic children aged 15 months to five years already established on inhaled prophylactic medication delivered through a large volume spacer. The prescribed drug regimens varied between subjects. This was an observational study using an electronic inhaler timer device to record the date and time of each actuation of the aerosol canister. Diary cards were used for parallel recording of symptoms and parentally reported compliance with a drug regimen. RESULTS: Variable and generally poor compliance was demonstrated with a median of 50% of study days with full compliance (subject range 0-94%) and an overall median of 77% of prescribed doses of therapy taken during the study period. No relation was found between frequency of prescribed regimen and good compliance. Day care was associated with poorer compliance. No relation between good compliance and low symptom scores was found. CONCLUSION: Compliance with inhaled prophylactic therapy is poor in preschool children with asthma whose medication is administered under parental supervision.

Administration, Inhalation↗
PubMed1995

Evaluation of the in vitro cariogenic potential of Streptococcus mutans strains isolated from 12-year-old children with differing caries experience.

The limited usefulness of caries activity tests based solely on counts of mutans streptococci has been recognised increasingly. Such tests do not account for potential differences in cariogenicity of Streptococcus mutans strains harboured by individual patients. Hence, this study describes the evaluation of a simple and inexpensive method involving the dissolution of powdered hydroxyapatite as a means of determining the cariogenic potential of 64 freshly isolated strains of S. mutans from 24 children. Whilst it is apparent that differences between strains isolated from individuals could be demonstrated using this test, the variability observed was such that it was not possible to relate in vitro cariogenicity to actual clinical caries experience.

Anions↗
PubMed1995

Methods for improving the repeatability of automated ECG analysis.

Statistically-based smoothing techniques are described which have been applied to the existing framework of the Glasgow ECG Analysis program. These methods have been designed with the aim of improving repeatability in the computer interpretation of ECGs which have been recorded either several minutes or 24 hours apart from patients in a clinically stable condition. With respect to the ECG diagnosis of Left Ventricular Hypertrophy (LVH), these flexible methods have the effect to reducing the number of inconsistent day-to-day interpretations by 36% from 33 to 21 in 330 pairs of ECGs recorded one day apart. Similarly, when comparing agreement in the diagnosis of LVH in 249 pairs of ECGs which were recorded several minutes apart, the number of discordant computer interpretations was 6 using the new methodology, compared with 13 using conventional criteria, i.e. there was a 54% reduction in disagreements.

Computer Graphics↗
PubMed1994

Is evidence for homoeopathy reproducible?

We tested, under independent conditions, the reproducibility of evidence from two previous trials that homoeopathy differs from placebo. The test model was again homoeopathic immunotherapy. 28 patients with allergic asthma, most of them sensitive to house-dust mite, were randomly allocated to receive either oral homoeopathic immunotherapy to their principal allergen or identical placebo. The test treatments were given as a complement to their unaltered conventional care. A daily visual analogue scale of overall symptom intensity was the outcome measure. A difference in visual analogue score in favour of homoeopathic immunotherapy appeared within one week of starting treatment and persisted for up to 8 weeks (p = 0.003). There were similar trends in respiratory function and bronchial reactivity tests. A meta-analysis of all three trials strengthened the evidence that homoeopathy does more than placebo (p = 0.0004). Is the reproducibility of evidence in favour of homoeopathy proof of its activity or proof of the clinical trial's capacity to produce false-positive results?

Adult↗
PubMed1994

Beta 2-agonists and running economy in prepubertal boys.

Asthmatic athletes (adults and junior) have competed successfully at the highest level for many years assisted by pre-event medication with beta 2-agonists. To examine the impact of beta 2-agonists upon submaximal running economy (oxygen consumption at a given submaximal work load), we studied 10 nonasthmatic boys (age, 10.4 +/- 0.48 years, mean +/- SD). They each completed submaximal (speeds, 7.2, 8.0 and 8.8 km/hr) and peak treadmill running protocols preceded by treatment with beta 2-agonist (terbutaline, 500 micrograms via nebuhaler) or placebo in a randomized, crossover single-blind study. No significant differences were found between running economy and heart rate during the submaximal exercise tests or between peak oxygen consumption (VO2), peak respiratory exchange ratio, peak heart rate (HR), or total running time during the peak VO2 test. Pretreatment with terbutaline did produce small but nonsignificant increases in aerobic fractional utilization (percent peak VO2 on drug: 65.9%, 72.6%, and 76.7% vs. placebo: 65.1%, 70%, and 75.5%), at the three submaximal work loads. Respiratory exchange ratio (RER) values were elevated throughout the submaximal tests (on drug: 0.94, 0.93, and 0.94 vs placebo: 0.91, 0.92, and 0.91, P < 0.05). No significant differences were found between drug and placebo for minute ventilation (VE) and ventilatory equivalent for oxygen (VE/VO2), at both submaximal and peak exercise intensities.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1994

Smoothing techniques for improving the repeatability of the automated diagnosis of inferior myocardial infarction.

This study describes the implementation of novel techniques that have been designed with the aim of improving the repeatability of the diagnostic section of the Glasgow electrocardiographic (ECG) analysis program. Specific reference is made to the agreement in consecutive computer-assisted diagnoses of inferior myocardial infarction (IMI). Inherent repeat variation was estimated in ECG parameters of interest and used in conjunction with smoothing methods to produce a continuous Q-wave index ranging from 0 (no IMI) to 1 (IMI). A decision as to the presence or absence of IMI was then made on the basis of this smooth index. The sensitivity and specificity of the new approach remain unchanged from the conventional procedure when analyzing single ECGs. However, consistency in interpretation of day-to-day and minute-to-minute ECG interpretations was enhanced. Specific reference is made to the agreement between consecutive pairs of computer-assisted diagnoses of ECGs from the same patient with which one or both interpretations was that of IMI.

Adult↗
PubMed1994

The effect of nebulised pentamidine on the concentration of intra-oral Candida albicans in HIV-infected patients.

This prospective study investigated whether oral candidal carriage in HIV-infected patients was altered by pentamidine therapy. Repeated oral rinses were taken from 56 HIV-positive patients over a 2-year period. Oral candidal carriage was investigated in two groups of patients, one receiving prophylactic pentamidine therapy and the other not receiving regular prophylaxis. Patients receiving pentamidine had lower concentrations of Candida albicans intra-orally than patients who did not receive it. Furthermore, patients who received pentamidine at one stage of the study, but not another, also had lower concentrations of C. albicans intra-orally when receiving pentamidine. These findings indicate that pentamidine is useful as a local agent for prophylaxis against intra-oral candidosis in HIV-infected patients.

Administration, Inhalation↗
PubMed1993

Umbilical cord clamping and preterm infants: a randomised trial.

OBJECTIVE: To investigate the clinical effects of regulating umbilical cord clamping in preterm infants. DESIGN: A prospective randomised study. SETTING: The Queen Mother's Hospital, Glasgow. SUBJECTS: 36 vaginally delivered infants over 27 and under 33 weeks' gestation. INTERVENTION: Holding the infant 20 cm below the introitus for 30 seconds before clamping the umbilical cord ("regulated" group, 17 patients), or conventional management ("random" group, 19 patients). MAIN OUTCOME MEASURES: Initial packed cell volume, peak serum bilirubin concentrations, red cell transfusion requirements, and respiratory impairment (assessed by ventilatory requirements, arterial-alveolar oxygen tension ratio over the first day in ventilated infants, and duration of dependence on supplemental oxygen). RESULTS: There were statistically significant differences between the two groups in mean initial packed cell volume (regulated group 0.564, random group 0.509) and median red cell transfusion requirements (regulated group zero, random group 23 ml/kg). 13 infants from each group underwent mechanical ventilation and showed significant differences in mean minimum arterial-alveolar oxygen tension ratio on the first day (regulated group 0.42, random group 0.22) and in median duration of dependence on supplemental oxygen (regulated group three days, random group 10 days). Differences in final outcome measures such as duration of supplemental oxygen dependence and red cell transfusion requirements were mediated primarily through arterial-alveolar oxygen tension ratio and also packed cell volume. CONCLUSIONS: This intervention at preterm deliveries produces clinical and economic benefits.

Bilirubin↗
PubMed1993

Plantar malignant melanoma in a white Caucasian population.

Fifty-one white Caucasian patients from the west of Scotland, with stage I primary malignant melanoma arising on the plantar surface were studied. Subungual lesions were excluded from the study. Clinical and pathological features were related to survival, and compared with a group of 239 cases of clinical stage 1 melanoma of the lower limb, excluding the foot, collected in the same geographical area over the same period of time (1979-84). The average age of patients with plantar melanoma was 67 years and was significantly older than those with leg melanomas, in whom the mean age was 53 years. Twenty patients with plantar lesions had superficial spreading melanomas, 27 had acral lentiginous melanomas, and four had nodular lesions. The female:male ratio was 3:2 which was significantly different from the 7:1 female:male ratio for leg lesions. Plantar melanomas were more commonly ulcerated (57%) than were melanomas on the leg (29%) [P < 0.001]. There was no significant difference between the mean thickness of melanomas on the plantar surface and those on the leg. Nine (17%) of the patients with plantar melanomas gave a clinical history of pre-existing naevus and in 27% there was pathological evidence of a pre-existing naevus. Disease-free survival at 5 years for the population with plantar melanomas was 82, 51 and 0%, respectively, for melanomas 0-1.49, 1.5-3.49 and over 3.5 mm in thickness. This compares with 95, 71 and 46%, respectively, for leg lesions. In each thickness category patients with leg melanomas have a significantly better survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗