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P M Fisher

Publications and source records attributed to P M Fisher.

At least 19 recordsLinked to original sources
PubMed2006

Capacity for 5-HT1A-mediated autoregulation predicts amygdala reactivity.

We examined the contribution of 5-HT1A autoreceptors (with [11C]WAY100635 positron emission tomography) to amygdala reactivity (with blood oxygenation level-dependent functional magnetic resonance imaging) in 20 healthy adult volunteers. We found a significant inverse relationship wherein 5-HT1A autoreceptor density predicted a notable 30-44% of the variability in amygdala reactivity. Our data suggest a potential molecular mechanism by which a reduced capacity for negative feedback regulation of 5-HT release is associated with increased amygdala reactivity.

Adult↗
PubMed2005

The use of lung dose-volume histograms in predicting post-radiation pneumonitis after non-conventionally fractionated radiotherapy for thoracic carcinoma.

AIMS: To assess the use of lung dose-volume histogram (DVH) parameters (specifically V20Gy) in the prediction of radiation pneumonitis for non-conventional fraction sizes used in the treatment of lung cancer. MATERIALS AND METHODS: Patients requiring computed tomography planning for thoracic radiotherapy between January 1999 and January 2002 were identified. The patients receiving radical or high-dose palliative radiotherapy had DVH produced routinely during planning. These were retrospectively reviewed and the case notes accessed for additional pre-treatment parameters, demographics and evidence of radiation pneumonitis. The severity of the pneumonitis was then scored using Radiation Therapy Oncology Group criteria. Data were analysed using the SPSS computer program. RESULTS: One hundred and sixty consecutive patients were reviewed. Ninety patients received hypofractionated treatment (fraction size > 2.5 Gy) and 57 continuous hyperfractionated accelerated radiation therapy (CHART) (fraction size 1.5 Gy). Lung V20Gy values ranged from 3% to 53%, with a median value of 24%. Only six patients reported grade 2, and 16 patients grade 3 pneumonitis. Two patients developed fatal, grade 5 pneumonitis. No correlation between pneumonitis score and V20Gy or other possible predictive factors was found. CONCLUSION: The 15% grade 2-5 pneumonitis rate we document is at the lower end of the spectrum reported in other studies. This suggests that using published data on limiting V20Gy values to reduce the risk of radiation pneumonitis can be extrapolated to planning treatment with non-conventionally fractionated radiotherapy.

Aged↗
PubMed2001

The impact of virtual simulation in palliative radiotherapy for non-small-cell lung cancer.

BACKGROUND AND PURPOSE: Radiotherapy is widely used to palliate local symptoms in non-small-cell lung cancer. Using conventional X-ray simulation, it is often difficult to accurately localize the extent of the tumour. We report a randomized, double blind trial comparing target localization with conventional and virtual simulation. METHODS: Eighty-six patients underwent both conventional and virtual simulation. The conventional simulator films were compared with digitally reconstructed radiographs (DRRs) produced from the computed tomography (CT) data. The treatment fields defined by the clinicians using each modality were compared in terms of field area, position and the implications for target coverage. RESULTS: Comparing fields defined by each study arm, there was a major mis-match in coverage between fields in 66.2% of cases, and a complete match in only 5.2% of cases. In 82.4% of cases, conventional simulator fields were larger (mean 24.5+/-5.1% (95% confidence interval)) than CT-localized fields, potentially contributing to a mean target under-coverage of 16.4+/-3.5% and normal tissue over-coverage of 25.4+/-4.2%. CONCLUSIONS: CT localization and virtual simulation allow more accurate definition of the target volume. This could enable a reduction in geographical misses, while also reducing treatment-related toxicity.

Carcinoma, Non-Small-Cell Lung↗
PubMed1996

A study of waiting times and waiting lists for radiation therapy patients.

A simple mathematical model based on queueing theory is introduced, and used to obtain a sensitive measure of the capacity of a radiation therapy centre to provide service. The model illustrates the relationships among the relevant variables: the patient waiting time, the number on the waiting list, the rate at which requests for radiation therapy are received and the rate at which courses of treatment are commenced. In particular, the rate at which the waiting time increases is equal to the difference between the request rate and the start rate, expressed as a fraction of the start rate, and is therefore a measure of the deficiency in service capacity of a facility. A study of the records of patients treated on the linear accelerators of the Tom Baker Cancer Centre from January 1991 to June 1994 shows that this relationship holds to a high degree of accuracy for average values of the various parameters in spite of the considerable variation in these values, and particularly variation in the individual waiting times. This finding suggests that such an approach would be useful in assessing and comparing the performance of radiation therapy facilities.

Alberta↗
PubMed1992

Mild and moderate dyskaryosis: can women be selected for colposcopy on the basis of social criteria?

OBJECTIVE: To describe the distribution of cervical intraepithelial neoplasia grades among women with mild and moderate dyskaryosis after a single cervical smear and to determine whether social criteria could help identify women who are at increased risk of grade II or III disease. DESIGN: Cross sectional analysis within a randomised prospective study. Subjects had a repeat smear, a colposcopic examination, and an excision biopsy of the transformation zone. In addition, women were asked to complete a social questionnaire. SETTING: Colposcopy clinic, Aberdeen. SUBJECTS: 228 women with a single smear test showing mild or moderate dyskaryosis. MAIN OUTCOME MEASURES: Histology, age, sexual and contraceptive history, cigarette smoking. RESULTS: 159 (70%) women had cervical intraepithelial neoplasia grades II or III. Among current smokers the prevalence of grade II and III disease was higher in women who smoked greater than or equal to 20 cigarettes a day (84%) than among those who smoked less (66%; p less than 0.04). Women with more than one sexual partner also had a higher prevalence (75%) than women with only one partner (50%; p = 0.0028). Use of oral contraceptives and younger age were not significantly associated. The prevalence of grade II or III disease was up to 66% in the lower risk groups. CONCLUSIONS: Because of the high prevalence of cervical intraepithelial neoplasia grades II and III in both the high and the low risk groups social factors are not useful for selecting women with mild or moderate dyskaryosis for either early referral to colposcopy or cytological surveillance.

Adult↗
PubMed1992

A population-based study of microinvasive disease of the cervix--a colposcopic and cytologic analysis.

A study of 61 cases of microinvasion of the cervix occurring in our population between 1980 and 1989 is reported. The mean age of the women was 39 years, compared with 30 years for cervical intraepithelial grade 3 (CIN III) and 47 years for frank invasion, respectively. Colposcopic suspicion of microinvasion was present in 31 cases, giving a sensitivity of colposcopic diagnosis of 50% and a specificity of 91%. In 21 cases (34%) there was no suspicion either cytologically or colposcopically of microinvasion. Colposcopy predicted microinvasion more accurately with increasing depth of invasion. In 28 women there had been previous smears within 10 years available for review. The time interval between the first abnormal smear and the histological diagnosis ranged from 1 month to 9.8 years (mean, 4 years).

Adult↗
PubMed1991

Pattern of treatment failure following laser for cervical intraepithelial neoplasia: implications for follow-up protocol.

In an effort to devise a rational protocol for the follow-up of patients who have had destructive treatment for cervical intraepithelial neoplasia (CIN), an analysis has been performed of treatment failures following laser therapy in 2130 women treated between 1980-1989. Of this group, 1253 women have been followed up for 3 years or more and 380 for 6 years or more. There have been 119 treatment failures (5.6%), of which 71% of the women had the second lesion detected during the first year of follow-up, 24% during the second year, 3.3% during the third year, and 1.7% during the sixth year. In 18% of these 119, the second lesion was detected colposcopically in the presence of negative cytology. There were two cases of microinvasion and one frankly invasive lesion following laser, all diagnosed during the second year of follow-up. Our data suggest that if the first year of follow-up includes at least one colposcopic examination, some second lesions will be diagnosed in the presence of negative cytology.

Adult↗
PubMed1986

Unstimulated renal venous renin ratio predicts improvement in hypertension following nephrectomy for unilateral renal disease.

The ability of renal venous renin ratio (RVRR) to predict the blood pressure response to nephrectomy was studied in 45 hypertensive patients followed for at least 1 year after nephrectomy. Twenty patients had unilateral chronic parenchymal renal disease (UCPR) and 25 patients had unilateral renal artery stenosis (RAS). The RVRR procedure was performed according to a strict protocol which included sodium restricted diet (40 mmol daily) and hospital admission, with one set of unstimulated samples collected after overnight recumbency, and at least one further set collected after sympathetic nervous system stimulation induced by tilting or i.v. diazoxide. In only 3 of 12 patients with serum creatinine 0.15 mmol/l or higher and presumed bilateral renal disease was hypertension improved. If these 12 patients are excluded, RVRR was a good predictor of outcome, but only if the question of unstimulated and stimulated ratios was considered. Whereas inclusion of stimulated ratios increased the predictive accuracy to 81% in RAS, and avoided two false-negatives, in UCPR the stimulated ratio created four false-positives. Since there were no false-negatives and six true-negatives in UCPR, overnight recumbent RVRR was a perfect predictor of outcome in this sub-group. It appears that RVRR without sympathetic stimulation is most reliable in UCPR, and RVRR during sympathetic stimulation in RAS, raising the question that renin regulation may be different in these two conditions.

Adolescent↗
PubMed1982

Fetal loss and maternal glucose intolerance. A retrospective study.

The premise that unexplained fetal loss is associated with maternal intravenous glucose intolerance (IVGT) has been studied retrospectively in three pregnancy related groups. In 97 women (Group A) who had stillbirths inadequately explained by obstetrical or necropsy findings, 24 per cent had abnormal IVGT tested six weeks postpartum. In 115 women (Group B) with histories of two or more spontaneous abortions (recurrent abortion) tested late in a subsequent successful pregnancy 26 per cent were abnormal. In 465 pregnancies of women with abnormal IVGT diagnosed during pregnancy (Group C) there were 19 perinatal deaths (12 stillbirths and 7 first week deaths) (Perinatal Mortality Rate 41 per 1000). Perinatal mortality characteristics which are similar to those found in insulin dependent diabetes namely a high incidence of major fetal abnormality (37 per cent) and the occurrence of hyaline membrane disease in term infants were observed. A causal association is postulated between inadequately explained stillbirth and recurrent abortion and abnormal maternal IVGT.

Abortion, Habitual↗
PubMed1980

The insulin response to glucose infusion in gestational diabetes.

Using a glucose infusion test insulin responses and insulin sensitivities were studied in 15 gestational diabetic women at 36-40 weeks gestation. In all women intravenous glucose tolerance had returned to normal at six weeks postpartum. Twelve women had a repeat glucose infusion test done 7-24 weeks (mean 17 weeks) postpartum. The results were compared with previously evaluated normal non-pregnant and normal pregnant standards and insulin responses below the normal 15th percentile were defined as "low". Twelve women had "low insulin responses in late pregnancy, and six had "low" insulin responses postpartum. The mean insulin sensitivity index of 1.34 +/- 1.21 (mean +/- SD) was significantly higher in the gestational diabetic group during pregnancy compared with a control pregnant group at 0.53 +/- 0.21 (p less than 0.01). The findings in this study support the hypothesis that gestational diabetes may arise in women who are unable to achieve adequate insulinogenic compensation to pregnancy. Increased insulin sensitivity in gestational diabetes may be a compensatory mechanism.

Adult↗
PubMed1980

The insulin response to glucose infusion in normal human pregnancy.

To study insulin response and insulin sensitivity a glucose infusion test was devised. Twenty normal non-pregnant and twenty normal pregnant women had an intravenous glucose tolerance test followed by a glucose infusion test. In a normal pregnant group at 38-40 weeks gestation (n = 20) the plasma insulin response was found to be 3.7 times greater than that observed in a normal non-pregnant group (n = 20), while in the normal pregnant group the insulin sensitivity index was only 18 per cent of that observed in the non-pregnant group. Intravenous glucose tolerance in the non-pregnant women was observed to correlate with the insulin sensitivity index (r = 0.61, p less than 0.05) but in the pregnant women it correlated with the insulin response (r = 0.66, p less than 0.01). These findings support the hypothesis that in the non-pregnant state intravenous glucose tolerance may be primarily related to insulin sensitivity while during pregnancy it may be related to the degree of compensatory hyperinsulinism.

Adult↗
PubMed1975

Palmitic acid concentrations and lecithin/sphingomyelin ratios in amniotic fluid.

Palmitic acid concentrations and L/S ratios have been estimated in amniotic fluid specimens with and without centrifugation and cold acetone precipitation. Although the number of cases was small, both of these measurements in uncentrifuged fluid seemed to reflect only indirectly on lung maturation in normal pregnancy while with centrifuged fluid the L/S value predicted RDS in one infant more reliably than palmitic acid concentration.

Acetone↗