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Biomedical subjects

A Dawson

Publications and source records attributed to A Dawson.

At least 55 records · Page 3Linked to original sources
PubMed2001

Haemangiopericytoma diagnosed from a metastasis 11years after surgery for "atypical meningioma".

Meningeal haemangiopericytoma (HPC) is a rare tumour often mistakenly reported as "vascular meningioma". Unlike meningiomas, HPC has a high rate of local recurrence and distant metastases, which may occur several years after initial treatment. We report a patient in whom a HPC was misdiagnosed as benign vascular meningioma and the patient discharged from follow-up. HPC was diagnosed 11 years later from biopsy of a skeletal metastasis. Histological review of the meningeal tumour confirmed the diagnosis of meningeal HPC. Meningeal HPCs resemble meningiomas clinically, radiologically and even light microscopically. As a result, they can be reported as atypical meningioma, as in this case. HPC's are more aggressive than typical meningiomas, with a high rate of recurrence and distant metastasis, often late in the course of the disease. Management of meningeal HPC differs from that of typical meningioma, with a need for post-operative radiotherapy and long-term follow-up.

Bone Neoplasms↗
PubMed2001

From safety contract to safety agreement.

1. Confusion and controversy continue to surround the definition and use of safety contracts. 2. A safety agreement based on Orlando's Nursing Theory may be a more practical, concise, and nurse-patient friendly means to promote patient safety. 3. The key ingredients in a safety agreement are identifying patients' immediate safety needs and decreasing patients' immediate distress related to safety through the nurse-patient relationship. 4. The value of a safety agreement lies not in the tool itself but in its promotion of a nurse-patient relationship that involves communication and collaboration.

Humans↗
PubMed2000

Rate of moult affects feather quality: a mechanism linking current reproductive effort to future survival.

Life-history theory proposes that costs must be associated with reproduction. Many direct costs are incurred during breeding. There is also evidence for indirect costs, incurred after breeding, which decrease survival and future reproductive success. One possible indirect cost identified in birds is that breeding activity in some way compromises plumage quality in the subsequent moult. Here we propose a mechanism by which this could occur. Breeding activity delays the start of moult. Birds that start to moult later also moult more rapidly--an effect of decreasing daylength. Could this result in poorer quality plumage? We kept two groups of male European starlings, Sturnus vulgaris, one on constant long days and the other on decreasing daylengths from the start of moult. Decreasing daylengths reduced the duration of moult from 103 +/- 4 days to 73 +/- 3 days (p < 0.0001). Newly grown primary feathers of birds that moulted fast were slightly shorter, weighed less (p < 0.05) and were more asymmetrical. They had a thinner rachis (p < 0.005), were less hard (p < 0.01) and less rigid (p < 0.05). They were also less resistant to wear so that differences in mass and asymmetry increased with time. There was no difference in Young's modulus. Poorer quality plumage will lead to decreased survival due to decreased flight performance and increased thermoregulatory costs. Thus, reproduction incurs costs through a mechanism that operates after the end of breeding.

Animals↗
PubMed2000

Lack of gonadotrophin-releasing hormone (GnRH) neuron response to decreasing photoperiod in thyroidectomized male starlings (Sturnus vulgaris).

Exposure of starlings to long days initially causes reproductive maturation, but eventually leads to photorefractoriness. During photorefractoriness, gonadotrophin-releasing hormone (GnRH) decreases in the GnRH cell bodies and fibers emanating from these to the median eminence, circulating gonadotrophin concentrations decrease to a minimum, and the gonads regress. Thyroidectomy profoundly affects these photoperiodic responses. In chronically thyroidectomized starlings, gonadal responses to changes in day length are attenuated. This investigation was conducted to determine whether, in the absence of gonadal responsiveness, the GnRH system of chronically thyroidectomized starlings responds to changes in day length. Two groups of thyroidectomized male starlings were transferred from short days (8L:16D) to long days (18L:6D) for four weeks, and testicular volume increased. One group was kept on long days (TxLD) and the other was returned to short days (TxSD). Testicular volume did not decrease in the TxSD group. The GnRH neurons of the two thyroidectomized groups were compared to those of two groups of intact starlings, one of them on long days and photorefractory (ILD), the other on short days and photosensitive (ISD). Group ILD had lower numbers of GnRH-stained cells than groups TxLD, TxSD and ISD, which did not differ in this respect. Similar differences were observed for GnRH cell size in the pre-optic area (POA) and for density of staining of GnRH fibers in the median eminence. The results confirm that thyroidectomy attenuates gonadal responses to change in day length and suggest that this results from an effect upon the central nervous system rather than a peripheral effect.

Animals↗
PubMed2000

Risk of hip fracture derived from relative risks: an analysis applied to the population of Sweden.

Bone mineral density measurements are widely used to estimate the relative risk of hip fracture. In addition, many other risk factors have been identified, some of which are known to add to the risk independently of other risk factors, including bone mineral density measurements. In this paper we develop an algorithm that converts relative risks for hip fracture to absolute (15 years and lifetime) risks, modeled on the population of Sweden. Lifetime risks increased as expected with increments in relative risk. Average lifetime risk in women at the age of 50 years was 22.7%, which increased to 64.9% when the relative risk was 6.0. In men the risk increased from 11.1% to 41.3%. The identification of high-risk groups had little effect on the specificity of assessments but increased the sensitivity over a wide range of assumptions. The increment in lifetime risk was relatively stable across all ages, reducing the complexity of computing lifetime risks from relative risk. The derivation of absolute risk from relative risk permits the optimization of selection of individuals or populations either for further risk assessment or for treatment.

Age Factors↗
PubMed2000

Long-term risk of osteoporotic fracture in Malmö.

The objectives of the present study were to estimate long-term risks of osteoporotic fractures. The incidence of hip, distal forearm, proximal humerus and vertebral fracture were obtained from patient records in Malmö, Sweden. Vertebral fractures were confined to those coming to clinical attention, either as an inpatient or an outpatient case. Patient records were examined to exclude individuals with prior fractures at the same site. Future mortality rates were computed for each year of age from Poisson models using the Swedish Patient Register and the Statistical Year Book. The incidence and lifetime risk of any fracture were determined from the proportion of individuals fracture-free from the age of 45 years. Lifetime risk of shoulder, forearm, hip and spine fracture were 13.3%, 21.5%, 23.3% and 15.4% respectively in women at the age of 45 years. Corresponding values for men at the age of 45 years were 4.4%, 5.2%, 11.2% and 8.6%. The risk of any of these fractures was 47.3% and 23.8% in women and men respectively. Remaining lifetime risk was stable with age for hip fracture, but decreased by 20-30% by the age of 70 years in the case of other fractures. Ten and 15 year risks for all types of fractures increased with age until the age of 80 years, when they approached lifetime risks because of the competing probabilities of fracture and death. We conclude that fractures of the hip and spine carry higher risks than fractures at other sites, and that lifetime risks of fracture of the hip in particular have been underestimated.

Age Factors↗
PubMed2000

Prediction of fracture from low bone mineral density measurements overestimates risk.

There is a well-established relationship between bone mineral density (BMD) and fracture risk. Estimates of the relative risk of fracture from BMD have been derived mainly from short-term studies in which the correlation between BMD at assessment and BMD in later life ranged from 0.8 to 0.9. Because individuals lose bone mineral at different rates throughout later life, the long-term predictive value of low BMD is likely to decrease progressively with time. This article examines and formalizes the relationship between current BMD, correlation coefficients, and long-term risk. The loss of predictive value has important implications for early assessment and supports the view that measurements should be optimally targeted at the time interventions are contemplated and, when necessary, repeated in later life.

Age Distribution↗
PubMed2000

Risk of hip fracture according to the World Health Organization criteria for osteopenia and osteoporosis.

The risk of hip fracture is commonly expressed as a relative risk. The aim of this study was to examine the utility of relative risks of hip fracture in men and women using World Health Organization (WHO) diagnostic criteria for low bone mass and osteoporosis. Reference data for bone mineral density (BMD) at the femoral neck, from the third National Health and Nutrition Examination Survey (NHANES III), were applied to the population of Sweden. Relative risks (RRs) were calculated from the known relationship between BMD at the femoral neck and hip fracture risk. The apparent prevalence of low bone mass and osteoporosis depended on the segment of the young population chosen for reference ranges. Using a reference derived from women aged 20-29 years, the prevalence of osteoporosis was 21.2% in women between the ages of 50 and 84 years and 6.3% in men. The RRs associated with osteoporosis depended markedly on the risk comparison. For example, in men or women aged 50 years, the RR of hip fracture in those with osteoporosis compared to those without osteoporosis was 7.4 and 6.1, respectively. The RR of those at the threshold value for osteoporosis compared to those with an average value for BMD at that age was 6.6 and 4.6 in men and women, respectively. RRs were lower comparing those at the threshold value compared to the risk of the general population at that age (4.2 and 2.9, respectively). When RR was expressed in relation to the population risk rather than to the risk at the average value for BMD, RR decreased at all ages by 37%. Such adjustments are required for risk assessment in individuals and for the combined use of different risk factors. Because the average T score at each age decreased with age, the RR of hip fracture at any age decreased with advancing age in the presence of osteoporosis. The decrease in relative risk with age is, however, associated with an increase in absolute risk. Thus, for clinical use, the expression of absolute risks may be preferred to relative risks.

Adult↗
PubMed2000

Consistency in the observation of features used to classify duct carcinoma in situ (DCIS) of the breast.

AIM: To determine interobserver and intra-observer agreement in the assessment of cytological grade and intraduct necrosis in pure duct carcinoma in situ (DCIS) of the breast. METHODS: Sixty unselected cases with illustrated diagnostic criteria were circulated to 19 practising histopathologists. RESULTS: Overall agreement was moderate for cytological grade in three categories: 71% agreement; weighted kappa (kappa w), 0.36; intraduct necrosis in three categories (absent, present, extensive): 76% agreement; kappa w, 0.57; and the Van Nuys classification system: 73% agreement; kappa w, 0.48. Agreement was no better among observers participating in the National External Quality Assurance Programme. Intra-observer agreement for cytological assessment (69.6% agreement; kappa w, 0.52) and intraduct necrosis (68.3% agreement; kappa w, 0.48) was moderate, suggesting that individual variation rather than precision of criteria contributes to the lack of agreement. CONCLUSIONS: Moderate agreement on observations can be achieved by non-specialist pathologists, with better agreement on necrosis than cytological grade. There was evidence of consistent individual bias towards over or under scoring cytological grade, which could be corrected with adequate and prompt feedback.

Breast Neoplasms↗
PubMed2000

Health-related quality of life in postmenopausal women with low BMD with or without prevalent vertebral fractures.

Fractures and subsequent morbidity determine the impact of established postmenopausal osteoporosis. Health-related quality of life (HRQOL) has become an important outcome criterion in the assessment and follow-up of osteoporotic patients. As part of the baseline measurements of the Multiple Outcomes of Raloxifene Evaluation (MORE) study, HRQOL was assessed in 751 osteoporotic (bone mineral density [BMD] T score > or = -2.5) women from Europe with or without vertebral fractures (VFX). This was done using the quality of life questionnaire of the European Foundation for Osteoporosis (QUALEFFO), Nottingham Health Profile (NHP) and the EQ-5D (former EuroQol). QUALEFFO contains questions in five domains: pain, physical function, social function, general health perception, and mental function. Each domain score and QUALEFFO total scores are expressed on a 100-point scale, with 0 corresponding to the best HRQOL. In comparison with patients without VFX, those with VFX were older (66.2 +/- 5.9 years vs. 68.8 +/- 6.3 years; p < 0.001), had higher prevalence of nonvertebral fractures (25% vs. 36%; p = 0.002), and higher QUALEFFO scores (worse HRQOL; total score, 26 +/- 14 vs. 36 +/- 17; p < 0.001). QUALEFFO scores increased progressively with increasing number of VFX, especially lumbar fractures (p < 0.001). Patients with a single VFX already had a significant increase in QUALEFFO scores (p < 0.05). Similar, though weaker, associations were seen for NHP and EQ-5D scores. This study confirms decreased HRQOL for patients with prevalent VFX. In osteoporotic patients, QUALEFFO scores change in relation to the number of VFX. QUALEFFO is suitable for clinical studies in patients with postmenopausal osteoporosis.

Aged↗
PubMed1999

Cytogenetic aspects of the Canadian early and mid-trimester amniotic fluid trial (CEMAT).

Cytogenetic results from a large multicentre randomized controlled study of 2108 amniotic fluids obtained at 11+0-12+6 weeks (EA) and 1999 fluids at 15+0-16+6 weeks (MA) were compared. There was no statistically significant difference in the rate of chromosome abnormalities (EA =1.9 per cent; MA=1.7 per cent) or level III mosaicism (EA=0.2 per cent; MA= 0.2 per cent) between the groups. Level I and Level II mosaicism occurred more frequently in MA. Maternal cell contamination was not significantly different between the groups, but maternal cells only were analysed from one bloody EA fluid. The number of repeat amniocenteses because of cytogenetic problems was 2.2 per cent in the EA group compared with only 0.3 per cent in the MA group. On average, culture of EA fluids required one day more than MA fluids. Although both culture success (97.7 per cent) and accuracy (99.8 per cent) were high for patients randomized to the EA group, routine amniocentesis prior to 13 weeks' gestation is not recommended for clinical reasons including an increased risk of fetal loss and talipes equinovarus.

Amniocentesis↗
PubMed1999

Fertility decline in aging roosters is related to increased testicular and plasma levels of estradiol.

The relationships between testicular and plasma hormone levels and the decline in fertility in aging roosters were examined. Body mass, testicular mass, and fertility were measured in roosters from 20 to 72 weeks of age. Plasma was assayed for LH and testosterone, and estradiol and testicular extracts were assayed for testosterone and estradiol contents. Fertility increased rapidly in young roosters to a peak of 96.2 +/- 3.9% at 37 weeks of age. Thereafter, fertility declined and by 72 weeks of age was significantly lower than at 37 weeks. Plasma LH reached 16.8 +/- 2.5 ng/ml at 27 weeks and remained high until 60 weeks of age, when it decreased significantly. Plasma and testicular testosterone levels increased from low levels in young birds to a peak that coincided with highest fertility and declined thereafter. Plasma and testicular estradiol showed a striking inverse relationship with testosterone. Plasma estradiol was 29.4 +/- 4.0 pg/ml in 20-week-old birds, decreased rapidly as testosterone increased, and increased again in older birds as testosterone decreased. Thus, the decline in fertility in aging roosters was associated with a decrease in plasma LH and testosterone and an increase in plasma and testicular estradiol. It is suggested that plasma levels of LH and testosterone in roosters are regulated by a negative feedback mechanism involving estradiol that is produced not only by the aromatization of testosterone in the brain but also by peripheral estradiol originating in the testes and that estradiol has a major role in the decline in fertility in aging roosters.

Aging↗
PubMed1999

Effect and offset of effect of treatments for hip fracture on health outcomes.

We investigated the cost-effectiveness of treatments that reduce the risk of hip fracture using a computer simulation model. Cost-effectiveness was measured as cost per quality-adjusted life-year (QALY) gained using a threshold value for cost-effectiveness of $30,000/QALY gained. The baseline simulations assumed a 5-year intervention that reduced the risk of hip fracture by 50% during the intervention period, and an effect which reversed to the pretreatment risk during the next 5 years. Sensitivity analyses included the effects of age, different fracture risks, and different treatment costs and duration of therapeutic effect once treatment was stopped. Cost-effectiveness was critically dependent upon absolute risk determined by the age and the relative risk of hip fracture at any given age. Reasonable cost-effectiveness was shown even with relatively high intervention costs for women with a risk about twice the average at the age of 70 or more years. Cost-effectiveness was critically dependent upon the assumptions made concerning offset of effect of intervention after the end of treatment. Where no residual effect was assumed, it was difficult to show cost-effectiveness from any intervention except for the most effective and least expensive. Conversely, cost-effectiveness improved considerably where effectiveness persisted for a longer time. These studies support the view that intervention in the elderly with agents affecting skeletal metabolism alone may be preferred to such interventions at the time of the menopause, and that offset time, hitherto poorly characterized, is a critical component of cost-effectiveness, particularly in younger women.

Age Factors↗
PubMed1999

Domiciliary midwifery support in high-risk pregnancy incorporating telephonic fetal heart rate monitoring: a health technology randomized assessment.

We conducted a health technology assessment of the care of women with high-risk pregnancies in the South Wales valleys. Women in the control arm were intended to receive conventional care with standard midwifery visits. Women in the intervention arm received additional or longer visits and domiciliary fetal heart rate telemonitoring. Eighty-one mothers were randomized. There were significant differences in midwifery intervention resources between domiciliary and control groups, with the former receiving a mean of 3.7 visits lasting 33.5 min, compared with 1.4 visits lasting 12.8 min for the latter. There were slightly more spontaneous labours and fewer Caesarean sections in the domiciliary group. Maternal satisfaction and anxiety were high in both groups. Domiciliary care increased the service costs by 21.02 Pounds per woman in terms of extra midwife travel and visiting time, and by a further 18.38 Pounds per woman in home monitoring equipment costs. This, however, was more than offset by health service savings from fewer clinic visits (35.60 Pounds) and fewer clinic ultrasound scans (9.01 Pounds). Adding the reductions in lost productivity to women and their partners (34.51 Pounds) suggests that domiciliary care was cheaper than conventional care, even if it did not greatly reduce inpatient days (a reduction nonetheless saving 184.24 Pounds). While clinical processes were similar in both groups, there were useful practical advantages and savings for patients and the health service from the domiciliary intervention.

Anxiety↗