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Biomedical subjects

A Hopper

Publications and source records attributed to A Hopper.

12 recordsLinked to original sources
PubMed2006

Dynamic production of hypoxia-inducible factor-1alpha in early transplanted islets.

More than half of transplanted beta-cells undergo apoptotic cell death triggered by nonimmunological factors within a few days after transplantation. To investigate the dynamic hypoxic responses in early transplanted islets, syngeneic islets were transplanted under the kidney capsule of balb/c mice. Hypoxia-inducible factor-1alpha (HIF-1alpha) was strongly expressed at post-transplant day (POD) 1, increased on POD 3, and gradually diminished on POD 14. Insulin secretion decreased on POD 3 in association with a significant increase of HIF-1alpha-related beta-cell death, which can be suppressed by short-term hyperbaric oxygen therapy. On POD 7, apoptosis was not further activated by continually produced HIF-1alpha. In contrast, improvement of nerve growth factor and duodenal homeobox factor-1 (PDx-1) production resulted in islet graft recovery and remodeling. In addition, significant activation of vascular endothelial growth factor in islet grafts on POD 7 correlated with development of massive newly formed microvessels, whose maturation is advanced on POD 14 with gradual diminution of HIF-1alpha. We conclude that (1) transplanted islets strongly express HIF-1alpha in association with beta-cell death and decreased insulin production until adequate revascularization is established and (2) early suppression of HIF-1alpha results in less beta-cell death thereby minimizing early graft failure.

Animals↗
PubMed2005

Beneficial effects of nerve growth factor on islet transplantation.

OBJECTIVE: Development of the Edmonton protocol was a pivotal contribution to clinical islet transplantation (ITx). Persistent limitations to ITx include insufficient supply and posttransplant functional failure of islets. In this study, nerve growth factor (NGF) was used to enhance both cultured and transplanted beta-cell function, thus achieving prolonged graft survival. METHODS: Fluorescence microscopy with ethidium bromide and SYTO green staining was used to evaluate balb/c mouse islet viability. Islets were syngeneically transplanted under the kidney capsule of recipients with streptozotocin-induced diabetes. Intraperitoneal glucose tolerance was used to test posttransplant function. RESULTS: Improved viability was found in murine islets cultured for 48 hours in 500 ng/mL NGF (P < .05). A submarginal islet mass (260 islet equivalents/recipient) was used for ITx. The NGF-culture resulted in prolonged islet survival (24.7 days vs 5.5 days without NFG culture, n = 6). Intravenous injection of NGF (6 mug) on the day of transplant and postoperative days (POD) 1 + 2 prolonged islet survival from 4.1 days (no treatment) to 13.2 days (n = 6). Glucose tolerance testing performed at posttransplant day 4 showed improvement at 60 and 120 minutes in recipients treated intravenously with NGF (blood glucose of 95 +/- 15 vs 210 +/- 78 and 57 +/- 6 vs 176 +/- 70 mg/dL, respectively). CONCLUSION: NGF may improve beta-cell function and result in prolonged survival of both cultured and transplanted islets.

Animals↗
PubMed2001

Memory impairments in adults with neurogenic communication disorders.

Over the past few decades, there has been increasing interest in the nonlinguistic, cognitive abilities of adults with neurogenic communication disorders. In particular, a growing literature has documented deficits in a number of memory functions in this population. The purpose of this article is to summarize that literature and provide an overview of the presence and nature of memory impairments in aphasia, right hemisphere disorders, traumatic brain injury, and dementia. Ways that memory impairments may interact with the communication abilities of individuals with neurogenic communication disorders also are discussed.

Aphasia↗
PubMed2000

Do hospital fall prevention programs work? A systematic review.

OBJECTIVES: To analyze published hospital fall prevention programs to determine whether there is any effect on fall rates. To review the methodological quality of those programs and the range of interventions used. To provide directions for further research. DESIGN: Systematic review of published hospital fall prevention programs. Meta-analysis. METHODS: Keyword searches of Medline, CINAHL, monographs, and secondary references. All papers were included that described fall rates before and during intervention. Risk ratios and 95% Confidence Intervals (95% CI) were estimated and random effects meta-analysis employed. Begg's test was applied to detect possible publication bias. Separate meta-analysis regressions were performed to determine whether individual components of multifaceted interventions were effective. RESULTS: A total of 21 papers met the criteria (18 from North America), although only 10 contained sufficient data to allow calculation of confidence intervals. A rate ratio of <1 indicates a reduction in the fall rate, resulting from an intervention. Three were randomized controlled trials (pooled rate ratio 1.0 (CI 0.60, 1.68)), seven prospective studies with historical control (0.76 (CI 0.65, 0.88)). Pooled effect rate ratio from these 10 studies was 0.79 (CI 0.69, 0.89). The remaining 11 studies were prospective studies with historical control describing fall rates only. Individual components of interventions showed no significant benefit. DISCUSSION: The pooled effect of about 25% reduction in the fall rate may be a result of intervention but may also be biased by studies that used historical controls not allowing for historical trends in the fall rate before and during the intervention. The randomized controlled trials apparent lack of effect might be due to a change in practice when patients and controls were in the same unit at the same time during a study. Studies did not analyze compliance with the intervention or opportunity costs resulting from the intervention. Research and clinical programs in hospital fall prevention should pay more attention to study design and the nature of interventions.

Accidental Falls↗
PubMed1998

Potent inhibitory activities of hydrophobic aci-reductones (2-hydroxytetronic acid analogs) against membrane and human low-density lipoprotein oxidation.

The effects of selected aci-reductones, which are hydrophobic ascorbate-related analogs including 4-chlorophenyl-2-hydroxytetronic acid (Cpd A), 4-(1,1'-biphenyl)-2-hydroxytetronic acid (Cpd B), and 4-(4'-chloro-1,1'-biphenyl)-2-hydroxytetronic acid (Cpd C), on membrane and low density lipoprotein (LDL) oxidation were assessed. Hepatic microsomal lipid peroxidation was induced by the ascorbate + Fe(II) chemical system. All three agents inhibited membrane lipid peroxidation in a concentration-dependent manner with the order of potency: Trolox (vitamin E) < or = Cpd A << Cpd B < Cpd C; based on the EC50 values, Cpd B and Cpd C were 11- and 19-fold, respectively, more potent than Trolox. In contrast to ascorbic acid, all three agents did not display any membrane prooxidative effect in the presence of iron. When human LDL was incubated with 10 microM of Cu(II), LDL oxidation, determined by the formation of thiobarbituric acid reactive substances, followed a typical sigmoidal curve with an initial lag phase. Preincubation of the LDL samples with low micromolar concentrations (1 and 3 microM) of each agents for 30 min before the addition of copper resulted in significant delays of the lag time of LDL oxidation, and the effectiveness of Cpd B and Cpd C was more prominent than that mediated by either Trolox or probucol. Since clinical evidence strongly supports the hypothesis that atherogenesis is initiated by LDL oxidation, the results suggest that these aryl tetronic acid analogs may serve as promising candidates for future therapeutic use as anti-atherogenic agents.

Animals↗
PubMed1998

A patient-centric approach to telemedicine database development.

Computer and telecommunications technologies have unleashed a wide range of powerful tools for gathering, storing, and distributing patient information. Computerized records enable healthcare providers to rapidly access patient data and to closely monitor patients from a distance. These significant advantages can be further extended by using the technology to more fully involve patients in their own healthcare management. A patient-centric approach to telemedicine means that the patient takes on additional responsibility and control, and the benefits from increased patient involvement will translate into improved compliance, reduced litigation, lower costs, and better outcomes. Furthermore, there are often important ethical questions that are best decided by the informed patient. Patients have a right to know what information is being gathered and who will be authorized to access that information. Current health information systems do not adequately address these issues, and telemedicine applications--particularly home based telemedicine--is forcing everyone to take a closer look at patients' roles in their own healthcare. In this presentation, a patient-centric home telemedicine database is described, the limitations are discussed, and future directions are proposed.

Computer Communication Networks↗
PubMed1997

Screening for diabetic retinopathy in primary care: retinal photography alone can be used efficiently and effectively to exclude those with sight threatening lesions.

BACKGROUND: Good screening performance of retinal photography and ophthalmoscopy together in screening for diabetic retinopathy in primary care have been reported. This study reanalysed the data to evaluate the screening performance of photography alone. METHODS: One thousand and ten patients screened by fundal photography and ophthalmoscopy were studied retrospectively. Fundal photographs were quality graded with poor quality pictures being excluded from the analysis. Each patient was reviewed initially by both retinal photographs and ophthalmoscopy by an ophthalmologist, the "gold standard". Six months later the fundal photographs were reviewed and reported in a blinded manner by the ophthalmologist. RESULTS: Two thousand and fourteen photographs were obtained, of which 162 (8%) had to be excluded because of poor quality. On review of the remaining 1852 photographs in isolation, of 77 cases of severe retinopathy as determined by the "gold standard", 67 had severe changes on photography--detection rate 87%. Of the 1775 cases without sight threatening retinopathy only five were judged to have sight threatening changes on photography--false positive rate 0.3%. Considering sight threatening and background retinopathy together, the detection rate was 69% (257 of 375) and the false positive rate 1.6% (23 of 1477). CONCLUSION: Good quality fundal photographs alone seem specific enough to screen for sight threatening diabetic retinopathy, but will underdetect background retinopathy.

Diabetic Retinopathy↗
PubMed1996

Adding retinal photography to screening for diabetic retinopathy: a prospective study in primary care.

OBJECTIVE: To evaluate whether adding retinal photography improved community screening for diabetic retinopathy. SETTING: Mobile screening unit at rural and urban general practices in south west England. SUBJECTS: 1010 diabetic patients from primary care. DESIGN: Prospective study; patients were examined by ophthalmoscopy by general practitioners or opticians without fundal photographs and again with photographs, and assessments were compared to those of an ophthalmologist. MAIN OUTCOME MEASURES: Whether fundal photography improved the sensitivity of detection of retinopathy and referrable diabetic retinopathy, and whether this sensitivity could be improved by including a review of the films by the specialist. RESULTS: Diabetic retinopathy was detected by the ophthalmologist in 205 patients (20.5%) and referrable retinopathy in 49 (4.9%). The sensitivity of the general practitioners and opticians for referrable retinopathy with ophthalmoscopy was 65%, and improved to 84% with retinal photographs. General practitioners' sensitivity in detecting background retinopathy improved with photographs from 22% to 65%; opticians' sensitivity in detecting background retinopathy improved from 43% to 71%. The sensitivity of detecting referrable retinopathy by general practitioners improved from 56% to 80% with photographs; for opticians it improved from 75% to 88%. CONCLUSIONS: Combining modalities of screening by providing photography with specialist review of all films in addition to direct ophthalmoscopy through dilated pupils improves assessment and referral for diabetic retinopathy by general practitioners and opticians. With further training and experience, primary care screeners should be able to achieve a sensitivity that will achieve an effective, acceptable, and economical community based screening programme for this condition.

Ambulatory Care↗
PubMed1991

Quality assurance in outpatient departments.

Outpatients departments are prime targets for quality assurance. They are probably the most visible department of a general hospital in terms of patient throughput and, clearly, the service quality standards projected to patients will significantly influence their perceptions of the hospital as a whole. Angela Hopper describes a research project funded by the Institute's Health Services Management Development Trust.

Attitude to Health↗
PubMed1982

Rat fetal development and maternal exposure to trichloroethylene 100 p.p.m.

Thirty-two inbred Wistar rats (study group) were exposed to trichloroethylene 100 p.p.m. in air for 4 h daily from day 8 to day 21 of pregnancy. A control group (31 rats) was exposed to the same experimental conditions but without the addition of trichloroethylene. All the rats were sacrificed on the 21st day of pregnancy and the ovaries, uterus, liver, lungs, heart and the fetuses were examined. There was no evidence of teratogenesis, but a delay in fetal maturation was suggested by reduced fetal weight (P less than 0.05) and by an increase in bipartite or absent skeletal ossification centres (P less than 0.005).

Abnormalities, Drug-Induced↗