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Biomedical subjects

A M Bruce

Publications and source records attributed to A M Bruce.

11 recordsLinked to original sources
PubMed2005

Gender differences in balance performance at the time of retirement.

BACKGROUND: Impairments in balance performance are a commonly accepted risk factor for falling in older people. Since there is a higher reported incidence of falling in women, it is of interest to test whether this correlates with poorer balance performance in women than men at the time of retirement in order to plan health promotional strategies. The purpose of this study was to investigate whether any gender differences exist in balance performance in people approaching retirement age. METHODS: Ninety-seven healthy volunteers (44 males, 53 females) planning to retire shortly were enrolled in the study (age range 50-67 years). Balance assessments during quiet standing were performed under various conditions; feet together eyes open, feet together eyes closed and single limb stance eyes open. The range of centre of pressure displacement in both the anterior-posterior and medial-lateral planes was collected for each task using a force platform. FINDINGS: For several of the balance tasks the men exhibited a statistically significant larger range of centre of pressure displacement than the women (P<0.01). However, after normalising the data for height, no gender differences were seen. Over half of the group failed to complete all three single limb stance trials on both limbs. INTERPRETATION: When the data was normalised for height, no differences were found in static balance performance between men and women of retirement age. A number of participants demonstrated balance impairments whilst performing the single limb stance likely to affect functional activities. Health promotional messages should be targeted equally at men and women.

Aged↗
PubMed1998

Estimation of the incidence of late bladder and rectum complications after high-dose (70-78 GY) conformal radiotherapy for prostate cancer, using dose-volume histograms.

PURPOSE: To investigate whether Dose-Volume Histogram (DVH) parameters can be used to identify risk groups for developing late gastrointestinal (GI) and genitourinary (GU) complications after conformal radiotherapy for prostate cancer. METHODS AND MATERIALS: DVH parameters were analyzed for 130 patients with localized prostate cancer, treated with conformal radiotherapy in a dose-escalating protocol (70-78 Gy, 2 Gy per fraction). The incidence of late (>6 months) GI and GU complications was classified using the RTOG/EORTC and the SOMA/LENT scoring system. In addition, GI complications were divided in nonsevere and severe (requiring one or more laser treatments or blood transfusions) rectal bleeding. The median follow-up time was 24 months. We investigated whether rectal and bladder wall volumes, irradiated to various dose levels, correlated with the observed actuarial incidences of GI and GU complications, using volume as a continuous variable. Subsequently, for each dose level in the DVH, the rectal wall volumes were dichotomized using different volumes as cutoff levels. The impact of the total radiation dose, and the maximum radiation dose in the rectal and bladder wall was analyzed as well. RESULTS: The actuarial incidence at 2 years for GI complications > or =Grade II was 14% (RTOG/EORTC) or 20% (SOMA/LENT); for GU complications > or =Grade III 8% (RTOG/EORTC) or 21% (SOMA/LENT). Neither for GI complications > or =Grade II (RTOG/EORTC or SOMA/LENT), nor for GU complications > or =Grade III (RTOG/EORTC or SOMA/LENT), was a significant correlation found between any of the DVH parameters and the actuarial incidence of complications. For severe rectal bleeding (actuarial incidence at 2 years 3%), four consecutive volume cutoff levels were found, which significantly discriminated between high and low risk. A trend was observed that a total radiation dose > or = 74 Gy (or a maximum radiation dose in the rectal wall >75 Gy) resulted in a higher incidence of severe rectal bleeding (p = 0.07). CONCLUSIONS: These data show that dose escalation up to 78 Gy, using a conformal technique, is feasible. However, these data have also demonstrated that the incidence of severe late rectal bleeding is increased above certain dose-volume thresholds.

Dose-Response Relationship, Radiation↗
PubMed1996

Evidence for early and persistent impairment of salivary gland excretion after irradiation of head and neck tumours.

Salivary gland scintigraphy with technetium-99m pertechnetate was used to follow changes in the excretion and uptake function of the major salivary glands until 1 year after irradiation. Twenty-five patients who received radiotherapy for head and neck tumours were included in the study. Seventy-nine salivary glands (39 parotid and 40 submandibular) were evaluated in relation to the average received radiation dose. Salivary gland scintigraphy was performed before and 1, 6 and 12 months after radiotherapy. For each gland the excretion response to carbachol, evaluated by calculation of the salivary excretion fraction (SEF), the cumulative gland uptake (CGU) and the absolute excreted activity (AEA) at various intervals after radiotherapy were compared with the baseline values. The excretion response decreased in 20 of 25 patients at 1 month after radiotherapy. One month after radiotherapy both SEF and AEA decreased significantly in relation to the radiation dose. These decreases in excretion parameters persisted during the follow-up period. Parotid excretion was affected significantly more than submandibular excretion. CGU values did not change significantly until 6 months after radiotherapy, but at 12 months a significant decrease related to radiation dose was observed. Xerostomia was assessed during radiotherapy and on the days of the scintigraphic tests. The incidence of xerostomia did not correspond to the effects observed in the scintigraphic studies. It is concluded that radiotherapy induces early and persistent impairment of salivary gland excretion, related to the radiation dose. This impairment is stronger in parotid glands than in submandibular glands.

Dose-Response Relationship, Radiation↗
PubMed1995

Variation in volumes, dose-volume histograms, and estimated normal tissue complication probabilities of rectum and bladder during conformal radiotherapy of T3 prostate cancer.

PURPOSE: To determine the pattern of changes of rectum and bladder structures during conformal therapy of T3 prostate cancer and the impact of these changes on the accuracy of the dose-volume histograms (DVHs) and normal tissue complication probabilities (NTCPs) of these organs, based on the planning computed tomography (CT) scan only. METHODS AND MATERIALS: For 11 T3 prostate cancer patients treated with conformal therapy, three repeat CT scans were made in Weeks 2, 4, and 6 of the treatment. The bony anatomy was aligned with the planning CT scan, using three dimensional (3D) chamfer matching. The internal and external surfaces of rectum and bladder were contoured in each scan. Three volumes were calculated for each organ: solid organ (including filling), filling, and wall volume. DVHs and NTCPs were calculated for all structures. RESULTS: The solid organ and filling volumes varied considerably between patients and within a patient and they decreased with increasing treatment time. The largest patient variation was seen for patients with large initial filling volumes. The variations of rectum and bladder wall volumes during treatment were 9 and 17% (1 standard deviation (SD)), respectively, with no time trend. The changes of the high dose (> 80 and 90% of the prescribed dose) volumes of the rectum in response to rectum filling differences were proportional to the whole rectum volume changes. The variation of the high-dose rectum wall volume was relatively small (14%, 1 SD). As a result, the NTCPs of rectum and rectum wall were the same overall and the variation of the NTCPs during treatment was about 14% (1 SD) and not correlated with rectum filling. The variation of the high-dose bladder volumes (about 14%, 1 SD) was smaller than the variation of the whole bladder volumes (30%, 1 SD). The high-dose bladder wall volume decreased significantly due to wall distention as the bladder filling increased. As a result of this complex pattern, the variation of NTCPs of bladder (85%, 1 SD) and bladder wall (88%, 1 SD) during treatment was large and significantly correlated with bladder filling. CONCLUSIONS: The planning CT scan overestimates rectum and bladder filling during treatment. Furthermore, the variation of filling is so large that only the wall structures have relatively constant volumes during treatment. For the rectum wall, the DVHs and NTCPs, as estimated from the initial scan, are representative for the whole treatment, because no correlation was seen between these parameters and organ filling. For the bladder wall, however, such a correlation was present and consequently, the initial bladder wall DVHs and NTCPs can only be representative for the whole treatment, if the bladder filling can be kept reasonably constant during treatment.

Anthropometry↗
PubMed1990

Electroretinograms in microcephaly with chorioretinal degeneration.

We recorded full-field electroretinograms from a family with two daughters with microcephaly and chorioretinal degeneration and a third daughter and mother with microcephaly without chorioretinal degeneration. The two siblings with inferior chorioretinal degeneration showed electroretinographic responses to 0.5-Hz white light that were reduced 60% to 70% below normal, suggesting that the loss of photoreceptor function exceeded the areas of visible atrophy. The mother and third daughter had normal electroretinograms. The two siblings, ages 12 and 21 years, had virtually the same electroretinographic amplitudes. In a second family, a man with microcephaly and inferior chorioretinal degeneration, examined at ages 9 and 23 years, also showed 60% to 70% reduction in electroretinographic responses to 0.5-Hz white light and showed no change in amplitudes over the 14-year interval. These findings suggest that the chorioretinal degeneration sometimes associated with microcephaly is stable in young adult life, although the long-term prognosis remains to be defined.

Adolescent↗
PubMed1990

Time-course of the antihypertensive and autonomic effects of regular endurance exercise in human subjects.

To assess the role of different factors on the long-term antihypertensive effect of regular exercise we examined the time course of changes in haemodynamics, oxygen consumption and plasma noradrenaline in 10 normal healthy subjects. For 12 weeks, subjects performed alternating months of training and detraining in a random order. Training involved 40 min of bicycle exercise three times per week at 60-70% of maximum work. Steady-state changes at the end of 1 month's exercise were: (1) falls in resting blood pressure when supine and erect by 8/5 and 10/6 mmHg, respectively (P less than 0.01); (2) a reduction in the total peripheral resistance index of 14%; (3) an increase in maximum oxygen consumption of 14% (P less than 0.005); and (4) a fall in plasma noradrenaline of 21% (P less than 0.05). A significant fall in blood pressure occurred at the third training bout (P less than 0.005), at the beginning of the second week, and no further reduction occurred beyond the fourth bout of exercise. The reduction in plasma noradrenaline concentration was confined to the second half of the month in which exercise took place and lagged behind the blood pressure changes. There were significant differences between the rates of the initial fall of blood pressure and noradrenaline, and the times taken for the maximum changes to occur (P less than 0.05). During detraining, blood pressure remained low for 1-2 weeks after cessation of exercise, as did plasma noradrenaline. Both then rose gradually towards the initial sedentary levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

An electroretinographic and molecular genetic study of X-linked cone degeneration.

We evaluated full-field electroretinograms from members of a family with X-linked cone degeneration. The 15-year-old propositus had near normal visual acuity and a protan deficiency. His maternal grandfather and great uncle had a visual acuity of 20/200, a deficiency in color vision, and signs of macular degeneration; all had normal rod electroretinographic responses and diminished cone electroretinographic responses. The mother and maternal aunt of the propositus had normal visual acuity and diminished cone electroretinograms with predominant loss of red cone function. Their cone responses were greater than those of affected males. Genomic DNA isolated from these patients was analyzed with a red cone pigment gene cDNA probe that disclosed a 6.5-kilobase deletion in the red cone pigment gene. These findings substantiate that a defect in a gene encoding for a cone photoreceptor protein can lead to a cone photoreceptor degeneration.

Adolescent↗
PubMedDate not supplied

A suicide by thiopentone injection.

Post-mortem tissues from a thiopentone suicide were analysed by ultraviolet spectrometry and gas chromatography. The thiopentone concentrations found (0.6 mg/100 ml of blood and 2 6 mg/100 g of tissue) are consistent with those reported for 'anaesthetic' deaths where only thiopentone and other anaesthetic agents were present. The gas chromatographic method gave more accurate result with the tissues.

Anesthesia↗