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Biomedical subjects

P Mitchell

Publications and source records attributed to P Mitchell.

At least 145 records · Page 8Linked to original sources
PubMed2000

Secondary myelodysplastic syndrome/acute myeloid leukaemia following mitoxantrone-based therapy for breast carcinoma.

Of 1774 patients with breast cancer given mitoxantrone (MTZ) with methotrexate (n = 492) or with methotrexate and mitomycin C (n = 1282), nine developed MDS/AML after a median of 2.5 years. Median duration of survival from diagnosis of MDS/AML was 10 months and six patients died. The crude incidence of developing MDS/AML after MMM or MM chemotherapy was 15 per 100,000 patient years follow-up, while the actuarial risk was 1.1% and 1.6% at 5 and 10 years respectively. MTZ-based regimens carry a 10 x higher risk of subsequent MDS/AML compared to that seen in the general population.

Acute Disease↗
PubMed2000

Stereotactic radiosurgery and the risk of haemorrhage from cavernous malformations.

Eighteen patients with cerebral cavernous malformations were treated with single dose of cobalt 60 source stereotactic radiosurgery. All had suffered at least one haemorrhage prior to treatment with six suffering 2, four suffering 3 and one suffering 4. Mean follow-up was 4.5 years. A total of 36 pretreatment haemorrhages occurred in 139 patient years. The first haemorrhage each patient suffered was taken as the start of observation and not included in the rehaemorrhage rate calculation. Three posttreatment haemorrhages occurred in 81 patient years of observation. The annual haemorrhage rate thus fell from 13% before to 3.7% after treatment. The odds ratio was thus 0.29 with a 95% confidence interval of (0.08-0.97), but this must be interpreted with caution because of the prereferral selection of this group of patients. Three patients developed complications of radiosurgery, two of them recovered fully.

Adolescent↗
PubMed2000

Acute neuromedical and neurosurgical admissions. Standard and ultrafast MR imaging of the brain compared with cranial CT.

PURPOSE: To evaluate the role of standard and ultrafast MR brain imaging and compare the information with CT. MATERIAL AND METHODS: This was a prospective study of 114 patients with acute neurological symptoms and signs. CT brain examinations consisted of axial non-enhanced images. MR imaging consisted of standard spin-echo/fast spin-echo sequences and a series of rapid techniques including echoplanar and single shot fast spin-echo sequences. RESULTS: Using standard MR methods, 41% of the patients had all five sequences of good technical quality, while using ultrafast methods 81% of the patients had good technical quality examinations in all five sequences. In 3% of the cases, ischaemic stroke was incorrectly reported on CT. In 24% of the cases, MR gave extra diagnostic information not reported on CT and in a further 8%, one neuroradiologist reported the abnormality in agreement with the MR, whilst the other neuroradiologist reported the CT as normal. In 2 cases, subarachnoid haemorrhage was missed on MR. Subarachnoid haemorrhage was not shown on the ultrafast sequences. CONCLUSION: MR can be used to image acute neurological admissions with a high success rate, particularly using ultrafast methods. In many cases, MR provided extra information of direct clinical relevance not shown on CT.

Acute Disease↗
PubMed2000

Costing depression and its management: an Australian study.

OBJECTIVE: To examine the cost impact of referral to a Mood Disorders Unit (MDU), by comparing pre-service and post-service costs, and MDU and control samples. METHOD: We studied tertiary referral MDU patients and a control group of consultants' depressed patients, with the principal comparison intervals being: (i) 12 months prior to and (ii) 6 months following baseline assessment, with costs annualised to allow the impact of assessment and treatment recommendation to be determined. In addition, we assessed any 'personal cost' of depression. RESULTS: Following baseline assessment, MDU referrals showed a reduction in costs, while controls' costs increased, largely driven by contrasting directions in hospitalisation and social welfare costs. We identify variables associated with high and increased costs, including features of the earlier stages of the disorder, whether social welfare was received, diagnostic subtype and personality dysfunction, with multivariate analyses refining the variable sets. Self-report data indicated that patients judged the 'personal cost' of depression to exceed more formal cost parameters, so that to experience depression is itself depressogenic. CONCLUSIONS: This first Australian attempt to cost depression and its management in the clinical setting more provides a methodology for wider application in service evaluation studies rather than delivers an unequivocal answer to whether a specialist Mood Disorders Unit is cost efficient or not.

Adult↗
PubMed2000

Long-term topical timolol and blood lipids: the Blue Mountains Eye Study.

OBJECTIVES: To examine whether an association exists between long-term use of topical timolol and blood lipids, including high-density lipoprotein cholesterol (HDL-C), cholesterol, and triglycerides, among participants of the Blue Mountains Eye Study. METHODS: From 1992 through 1994, a detailed medical and eye examination was performed in 3,654 people aged 49 years or older, representing 82% of permanent residents in two postcode areas west of Sydney. Glaucoma and ocular hypertension were diagnosed, and an ophthalmic history was taken, including use of topical timolol. Fasting blood tests were performed in 89% of subjects. Lipid levels were compared in subjects using topical timolol for at least 1 year with those not using timolol, after excluding people using oral beta-blockers, topical beta1-selective agents, or oral lipid-lowering medications. RESULTS: Analyses compared blood lipids of 63 people who had used topical timolol for at least 1 year with 2,597 nonusers. No statistically significant differences were found in any blood lipid mean levels between treated and untreated people, after multivariate adjustment. However, subgroup analyses of men and women separately showed that male timolol users had a mean value of HDL-C 0.13 mmol/L (11%) lower then the mean value of male nonusers, while female timolol users had a mean value of HDL-C 0.09 mmol/L (5%) higher than the mean for female nonusers. There were no statistically significant associations between timolol treatment duration and HDL-C or other lipid levels. Previously reported adverse effects of oral beta-blockers on blood lipid levels were confirmed. CONCLUSIONS: These population-based data suggest that long-term administration of topical timolol for glaucoma or ocular hypertension can cause adverse effects on HDL-C in men, but not in women. The magnitude of the effect in men was similar to that previously described in a number of short-term studies.

Adrenergic beta-Antagonists↗
PubMed2000

The emergency department experience of chest pain patients and their intention to delay care seeking for acute myocardial infarction.

This study investigated how patients' emergency department experience was related to their intention to delay action in response to future symptoms of acute myocardial infarction. A sample of 426 persons admitted to the emergency department with a chief complaint of chest pain and released from the emergency department were contacted by telephone. Patients were queried about their affective response to the emergency department experience, their satisfaction with emergency department staff communication, their intention to delay prompt action for acute myocardial infarction symptoms in the future, the influence of others in the decision to seek care, and medical and demographic status. The results of a mixed model linear regression analysis showed that the less education patients had (p = 0.007), the less sure they felt that going to the emergency department had been "the right thing to do" (p = 0.004), and the greater the degree of embarrassment (p = 0.0001), the greater was the intention to delay action for future symptoms of acute myocardial infarction. The results also showed that those patients who were prompted by health professionals to go to the emergency department were less likely to report intentions to delay for future symptoms (p = 0.036). It is important that emergency department staff reassure chest pain patients who are sent home that they did the right thing by coming to the emergency department for their symptoms. Providers need to be particularly sensitive to feelings of embarrassment.

Chest Pain↗
PubMed2000

Risk analysis of treatment of unruptured aneurysms.

OBJECTIVES: To calculate the expected number of life-years saved by surgical treatment of unruptured intracranial aneurysms at ages over 20 years. METHODS: An actuarial risk analysis of the treatment of unruptured intracranial aneurysms based on data from the International Study of Unruptured Intracranial Aneurysms (ISUIA). The benefits of operative treatment are calculated in terms of average life-years saved. RESULTS: Results are presented as graphs of life-years saved or lost against age at the time of operative treatment for three groups of aneurysms: those under 10 mm in diameter with no history of subarachnoid haemorrhage (SAH) from another aneurysm, those under 10 mm in diameter and a history of previous SAH from a different aneurysm, and those over 10 mm in diameter. Life-years are lost at all ages in the group under 10 mm with no history of SAH. For the group under 10 mm with a history of SAH about 4 years are saved at age 20 declining to 0 at around age 50. For aneurysms 10 mm or more in diameter about 8 life-years are saved at age 20 declining to 0 at around 50. CONCLUSIONS: Clipping of unruptured aneurysms under 10 mm in diameter with no history of subarachnoid haemorrhage is not justified on actuarial grounds. Intervention in other unruptured aneurysms produces benefits in life expectancy up to the age of 50. There may be subgroups of aneurysms in which larger benefits exist.

Adult↗
PubMed2000

Estimate of the maximum time interval between formation of cerebral aneurysm and rupture.

The recent publication of the results of the international study on unruptured intracranial aneurysms highlighted a paradox: there do not seem to be enough unruptured aneurysms in the population to account for the observed incidence of subarachnoid haemorrhage. Some authors have suggested that the answer to this paradox is that most aneurysms that bleed do so shortly after formation. This would mean that the bulk of subarachnoid haemorrhages come from recently formed rather than long standing aneurysms. This paradox and proposed answer are examined. The available statistics on the incidence of subarachnoid haemorrhage, the prevalence of unruptured aneurysms, and the risk of bleeding from unruptured aneurysms are used to place a maximum on the time interval between aneurysm formation and rupture. For aneurysms less than 10 mm in diameter in persons with no history of subarachnoid haemorrhage, an estimate of less than 42 weeks was made. The null hypothesis that such aneurysms pose a constant risk with time is rejected with p <10(-9). In larger aneurysms the risk seems to be constant with time.

Humans↗
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed2000

Vision and low self-rated health: the Blue Mountains Eye Study.

PURPOSE: To assess the relationship between reduced vision and low self-rating of global health, after taking into account many other related factors. METHODS: The Blue Mountains Eye Study examined 3654 residents aged > or =49 years (82.4% response) in an area west of Sydney, Australia. Presenting and best-corrected visual acuity (VA) were measured before and after refraction using a LogMAR chart. During a face-to-face interview, self-rated health was assessed by asking: "For someone of your age, how would you rate your overall health?: excellent, good, fair, or poor." Information about demography, socioeconomic status, need for assistance in daily living activities, medical history, and health risk behaviors was also collected. Logistic regression analyses were performed after dichotomizing self-rated health as poor or fair (low) versus good or excellent. RESULTS: Among persons without visual impairment (defined from best-corrected VA in the better eye), 24.5% rated their health as either poor or fair, compared with 35.5% and 48.8% of persons with mild or moderate-to-severe visual impairment, respectively. In multivariate logistic regression models that included 17 other related factors, reduced vision was statistically significantly associated with lower self-rated health in persons aged <80 years. For each one-line (5 letter) reduction in best-corrected VA, there was 20% increased likelihood of low self-rated health, after adjustment for other factors found associated with self-rated health (multivariate-adjusted odds ratio 1.2, 95% confidence interval 1.1-1.3). In persons aged 80 years or older, reduced vision had no impact on global health rating. CONCLUSIONS: Decreased vision was found to have an independent impact on global health ranking by persons younger than age 80 years, but not by older persons in this population. Taking into account many other factors affecting perceived health, people younger than age 80 years who see well are also more likely to say that they feel well!

Activities of Daily Living↗
PubMed2000

Improving the selective use of plain radiographs in the initial evaluation of shoulder pain.

OBJECTIVE: In a previous retrospective study, we had found that shoulder radiographs were overused in the initial evaluation of patients presenting to the emergency department with shoulder pain. Our objective was to prospectively define clinical criteria that identify patients who have a low risk of radiographic findings that influence the management of the initial evaluation of shoulder pain in the emergency department. METHODS: All adult patients presenting to the emergency department of a university teaching hospital with shoulder pain were eligible to participate. Patients with deformities, penetrating wounds, referred pain, and those presenting for followup were excluded. Data were recorded prospectively using a standardized form. All radiographs were classified as therapeutically uninformative (TU) except fracture, acromioclavicular joint separation (> or =Grade 3), infection, or malignancy. A classification tree was used for analysis. RESULTS: Two hundred six patients had shoulder radiographs, of which 88% were TU. The model yielded 3 sets of low risk patients with a high percentage of TU radiographs: (1) no fall, no swelling (99% TU: 106 TU, 1 radiograph with lytic lesions in a cancer patient); (2) a fall, but no swelling, and no pain at rest (100% TU, n = 18); (3) a fall and pain at rest, but no swelling and normal range of motion (100% TU, n = 10). Not performing radiographs on these low risk patients would have decreased radiograph utilization from 52 to 18% of all shoulder patients seen. CONCLUSION: Our findings suggest that specific clinical criteria are able to identify patients who do not need radiographs as part of the initial management of shoulder pain. Prospective validation of these criteria are needed to confirm that these low risk patients can be safely evaluated without radiographs.

Adult↗
PubMed2000

Effect of the 30 degree lateral recumbent position on pulmonary artery and pulmonary artery wedge pressures in critically ill adult cardiac surgery patients.

BACKGROUND: Despite demonstrated benefits of lateral positioning, critically ill patients may require prolonged supine positioning to obtain reproducible hemodynamic measurements. OBJECTIVES: TO determine the effect of 30 degree right and left lateral positions on pulmonary artery and pulmonary artery wedge pressures after cardiac surgery in critically ill adult patients. METHODS: An experimental repeated-measures design was used to study 35 patients with stable hemodynamics after cardiac surgery. Subjects were randomly assigned to 1 of 2 position sequences. Pulmonary artery and pulmonary artery wedge pressures were measured in each position. RESULTS: Measurements obtained from patients in the 30 degree left lateral position differed significantly (all Ps < .05) from measurements obtained from patients in the supine position for pulmonary artery systolic, end-diastolic, and mean pressures. Pulmonary artery wedge pressures did not differ significantly; however, data were available from only 17 subjects. The largest mean difference in pressures between the 2 positions was 2.0 +/- 2.1 mm Hg for pulmonary artery systolic pressures, whereas maximum differences for end-diastolic and pulmonary artery wedge pressures were 1.4 +/- 2.7 mm Hg and 1.6 +/- 2.4 mm Hg, respectively. Clinically significant position-related changes in pressure occurred in 12 (2.1%) of 581 pressure pairs. Clinically significant changes occurred in end-diastolic pressure in 2 subjects and in pulmonary artery wedge pressure in 1 subject. CONCLUSIONS: In patients with stable hemodynamics during the first 12 to 24 hours after cardiac surgery, measurements of pulmonary artery and pulmonary artery wedge pressures obtained in the 30 degree lateral and supine positions are clinically interchangeable.

Adult↗
PubMed1999

Functions of the exosome in rRNA, snoRNA and snRNA synthesis.

The yeast nuclear exosome contains multiple 3'-->5' exoribonucleases, raising the question of why so many activities are present in the complex. All components are required during the 3' processing of the 5.8S rRNA, together with the putative RNA helicase Dob1p/Mtr4p. During this processing three distinct steps can be resolved, and hand-over between different exonucleases appears to occur at least twice. 3' processing of snoRNAs (small nucleolar RNAs) that are excised from polycistronic precursors or from mRNA introns is also a multi-step process that involves the exosome, with final trimming specifically dependent on the Rrp6p component. The spliceosomal U4 snRNA (small nuclear RNA) is synthesized from a 3' extended precursor that is cleaved by Rnt1p at sites 135 and 169 nt downstream of the mature 3' end. This cleavage is followed by 3'-->5' processing of the pre-snRNA involving the exosome complex and Dob1p. The exosome, together with Rnt1p, also participates in the 3' processing of the U1 and U5 snRNAs. We conclude that the exosome is involved in the processing of many RNA substrates and that different components can have distinct functions.

Base Sequence↗