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Biomedical subjects

H Brown

Publications and source records attributed to H Brown.

At least 37 records · Page 2Linked to original sources
PubMed2001

Utility values associated with blindness in an adult population.

AIM: To ascertain utility values associated with varying degrees of legal blindness. METHODS: A cross sectional study on three group of patients. There were: (1) 15 patients with complete absence of vision (no light perception) in at least one eye who were asked to assume a scenario of no light perception in the second eye as well, (2) 17 patients with light perception to counting fingers in the better seeing eye, and (3) 33 patients with 20/200-20/400 vision in the better seeing eye. Utility values were measured using the time trade-off and standard gamble methods in each of the three groups. RESULTS: The mean time trade-off utility value for the no light perception group with the theoretical scenario of bilateral absence of light perception was 0.26 (95% CI, 0.19-0.33). The mean utility value for the light perception to counting fingers group was 0.47 (95% CI, 0.33-0.61), and the mean utility value for the 20/200-20/400 group was 0.65 (95% CI, 0.58-0.72). Thus, patients with no light perception in one eye, who were presented with the same scenario in the second eye as well, were willing to trade almost 3 out of every 4 years of remaining life in return for perfect vision in each eye. Those with light perception to counting fingers would trade approximately 1 of 2 remaining years and those with 20/200-20/400 would trade approximately 1 of 3 remaining years. CONCLUSIONS: There is a wide range of utility values associated with legal blindness. The utility value decreases dramatically with perceived total loss of vision (absence of light perception in each eye), compared with counting fingers to light perception vision, indicating that the preservation of even small amounts of vision in patients with legal blindness is critically important to their wellbeing and functioning in life.

Adult↗
PubMed2001

Attitudes towards prenatal HIV testing and treatment among pregnant women in southern India.

During June and July 1999, oral interviews were conducted on 666 women seeking prenatal care at 9 medical facilities in Chennai and Mysore, India, to assess their attitudes towards prenatal HIV testing and antiretroviral prophylaxis for preventing perinatal HIV transmission if needed. Seventy-eight per cent were aware of the risk of perinatal HIV transmission and 36% knew that intervention could reduce the chances of such transmission. Eighty-six per cent would agree to undergo prenatal HIV testing but only 21% of all respondents would make this decision independently while 46% said their husband would have to decide. Of those women who would not agree to testing, 21% would agree if testing were compulsory. Ninety-seven per cent of respondents would undergo antiretroviral prophylaxis to prevent vertical transmission, and 94% would consider alternatives to breastfeeding if HIV positive. Considering its widespread acceptability, prenatal voluntary counselling and testing may be an affordable method of HIV prevention for this population.

AIDS Serodiagnosis↗
PubMed2001

Monitoring task loading with multivariate EEG measures during complex forms of human-computer interaction.

Electroencephalographic (EEG) recordings were made while 16 participants performed versions of a personal-computer-based flight simulation task of low, moderate, or high difficulty. As task difficulty increased, frontal midline theta EEG activity increased and alpha band activity decreased. A participant-specific function that combined multiple EEG features to create a single load index was derived from a sample of each participant's data and then applied to new test data from that participant. Index values were computed for every 4 s of task data. Across participants, mean task load index values increased systematically with increasing task difficulty and differed significantly between the different task versions. Actual or potential applications of this research include the use of multivariate EEG-based methods to monitor task loading during naturalistic computer-based work.

Adult↗
PubMed2000

Munc-18 associates with syntaxin and serves as a negative regulator of exocytosis in the pancreatic beta -cell.

The Munc-18 protein (mammalian homologue of the unc-18 gene; also called nSec1 or rbSec1) has been identified as an essential component of the synaptic vesicle fusion protein complex. The cellular and subcellular localization and functional role of Munc-18 protein in pancreatic beta-cells was investigated. Subcellular fractionation of insulin-secreting HIT-T15 cells revealed a 67-kDa protein in both cytosol and membrane fractions. Immunohistochemistry showed punctate Munc-18 immunoreactivity in the cytoplasm of rat pancreatic islet cells. Direct double-labeling immunofluorescence histochemistry combined with confocal laser microscopy revealed the presence of Munc-18 immunoreactivity in insulin-, glucagon-, pancreatic polypeptide-, and somatostatin-containing cells. Syntaxin 1 immunoreactivity was detected in extracts of HIT-T15 cells, which were immunoprecipitated using Munc-18 antiserum, suggesting an intimate association of Munc-18 with syntaxin 1. Administration of Munc-18 peptide or Munc-18 antiserum to streptolysin O-permeabilized HIT-T15 cells resulted in significantly increased insulin release, but did not have any significant effect on voltage-gated Ca(2+) channel activity. The findings taken together show that the Munc-18 protein is present in insulin-secreting beta-cells and implicate Munc-18 as a negative regulator of the insulin secretory machinery via a mechanism that does not involve syntaxin-associated Ca(2+) channels.

Animals↗
PubMed2000

Netlines

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Journal Article↗
PubMed2000

Netlines

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Journal Article↗
PubMed2000

Netlines

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Journal Article↗
PubMed2000

Netlines

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Journal Article↗
PubMed2000

Netlines

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Journal Article↗
PubMed2000

Converting visual acuity to utilities.

BACKGROUND: Utility theory can be used to quantify dysfunction associated with various diseases and thus can represent a "hard" measure of quality of life. By determining utility values, one can compare the quality of life of patients with ocular disease to that of patients with non-ophthalmic problems. We performed a study to determine whether utility values from patients with ocular disease are associated with clinical variables, including visual acuity in the better-seeing eye, and to develop a mathematical method for converting visual acuity to utility value, if there is an association between the two. METHODS: Cross-sectional study. A total of 239 patients from a tertiary care retinal practice with various ocular conditions, including macular degeneration, cataract, glaucoma and diabetic retinopathy, were interviewed under standardized conditions to determine their utility values by the time trade-off technique. Visual acuity, duration of visual loss and number of concomitant conditions were also determined. Multiple linear regression was performed to determine which variables were associated with utility values. RESULTS: The mean acuity in the better-seeing eye was 0.479 (near 20/40 vision). The mean utility value was 0.72. Accordingly, the average patient in our series was willing to trade 2.8 of every 10 remaining years of life to obtain perfect vision in both eyes. Utility value was significantly associated with visual acuity in the better-seeing eye (F = 69.1, p < 0.001). Other variables were not significantly associated with utility value. The association with duration of visual loss approached statistical significance (p = 0.075). Utility values (U) for patients with ocular disease can be derived from the following formula: U = (0.374)(visual acuity in better-seeing eye) + 0.514. INTERPRETATION: Utility values from patients with ocular disease were strongly associated with visual acuity and could be estimated mathematically.

Aged↗
PubMed2000

Incremental cost effectiveness of laser photocoagulation for subfoveal choroidal neovascularization.

OBJECTIVE: To perform a patient preference-based, incremental cost-effectiveness analysis for laser treatment of subfoveal choroidal neovascularization. DESIGN: Computer-based econometric modeling. METHODS: The cost effectiveness of laser photocoagulation therapy was compared with the natural course of subfoveal choroidal neovascularization. The model applied long-term visual data from previous clinical trials, utility analysis (which reflects patient perceptions of quality of life associated with a health state), decision analysis with Markov modeling, and the economic principles of present value analysis with discounting to account for the time value of money. DATABASE: Data from patients eligible for treatment of subfoveal choroidal neovascularization obtained by researchers in the Macular Photocoagulation Study were used for the analysis. INTERVENTION: Modeled laser therapy for subfoveal choroidal neovasacularization in patients with age-related macular degeneration. MAIN OUTCOME MEASURE: Cost per quality-adjusted life-year ($/QALY gained) associated with laser therapy. RESULTS: Laser photocoagulation therapy for subfoveal choroidal neovascularization, as compared with no treatment, resulted in a mean gain of 0.257 QALYs per treated patient. Using a yearly discount rate of 3% to account for the time value of money and inflation, the resultant $/QALY gained was $5629. Sensitivity analysis used in the cost-effectiveness analysis resulted in a $/QALY gained of $4974 with no gained discount rate and $11,633 with a yearly discount rate of 10%. CONCLUSIONS: The incremental expense of laser therapy for the treatment of subfoveal choroidal neovascularization appears to be highly cost effective. The result, which takes into account patient preference-based utility data, compares quite favorably with other interventional therapies across different medical specialties.

Aged↗
PubMed2000

Project 2000: a study of expected and experienced stressors and support reported by students and qualified nurses.

The present study was conducted in the light of major reforms to nurse education which have taken place in the United Kingdom since 1989. The study aimed to identify initially perceived stressors and coping resources and subsequently, to compare these with actually reported stressors and available resources, during a critical period in nurses' careers. Three groups of nurses participated who were undertaking, or had recently completed, the first Project 2000 course at a university in the south of England. Participants were given an open-ended questionnaire and asked to describe potential difficulties, and the coping resources they anticipated using, in a subsequent 6-month period. Following analysis of the descriptors a structured questionnaire was developed to measure actually experienced difficulties and coping resources that were reported; this was completed by the three groups 6 months after the initial phase of the study. Both student and staff nurse groups reported fewer stressors and more resources than they had predicted. Students anticipated difficulties with competence but actually reported financial difficulties. They experienced support from mentors although this was not anticipated. Newly qualified staff nurses experienced fewer difficulties with meeting personal expectations of the role than they had anticipated. They reported more use of emotion-focused coping and less professional support than the student groups. The results are discussed in relation to training needs.

Adolescent↗
PubMed2000

Anatomy and blood supply of the lower four cranial and cervical nerves: relevance to surgical neck dissection.

This study is a continuation of previous work searching for possible anatomic reasons to explain variable and usually unpredictable postoperative pain and dysfunction after the same nerve losses with similar neck dissection operations. The study consisted of dissections of 19 deceased unpreserved elderly subjects arterially injected with dyed latex. Of the 19 subjects, 14 had brain stem and cervical spinal cord dissections, and all had neck dissections. The findings suggested two possible anatomic reasons for the pain and dysfunction: (i) The intracranial anatomy of the lower four cranial nerves, the glossopharyngeal (IX), the vagus (X), the spinal accessory (XI), and the hypoglossal (XII), was just as variable as the previously reported peripheral spinal accessory nerve plexus; and (ii) Both the intracranial and neck dissections indicated that the blood supply to the lower four cranial and cervical nerves, particularly to the brachial plexus, could be impaired by atherosclerosis and/or neuroforaminal impingement or operative loss. This loss of blood supply theoretically could result in ischemia as another possible cause of postoperative pain and dysfunction. It is concluded that because of the potential importance of each nerve and vessel, often unknown at operation, it is very important to spare as many of them as possible to avoid subsequent painful impairment.

Accessory Nerve↗