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Biomedical subjects

R Wright

Publications and source records attributed to R Wright.

340 records · Page 19Linked to original sources
PubMedDate not supplied

Dialysate contamination and back filtration may limit the use of high-flux dialysis membranes.

Endotoxins, or fragments thereof, can reach the blood stream of dialysis patients, transported by diffusion and connection across the intact high-flux membrane. This transfer depends upon the phenomenon of back filtration. Back filtration generally occurs under conventional high-flux dialysis conditions with membranes having an ultrafiltration coefficient in blood (UF-C) above 20 ml/hr/m2/mmHg. The clinical consequences of back filtration vary from center to center depending primarily on the quality of dialysate. We therefore surveyed the bacterial and endotoxin levels of purified water and effluent dialysate in a cross section of dialysis centers in the central United States. Using a high recovery medium, we found that 53% of the centers had bacterial counts above the Association for the Advancement of Medical Instruments standard in water (20% cfu/ml) and 35% above the standard in dialysate (2,100 cfu/ml). Endotoxin concentrations higher than 5.0 EU/ml in both water and dialysate were found in 4% and 11.8% of the centers, respectively. Since high-flux membranes are believed to be of benefit for long-term dialysis patients, manufacturers will have to offer dialysate preparation systems with additional safety features. The proper membrane design will be a key to the success of such systems.

Colony Count, Microbial↗
PubMedDate not supplied

Magnetic resonance imaging of the Dandy-Walker malformation.

Five cases of the Dandy-Walker malformation are described using the magnetic resonance (MR) scan as a primary imaging technique. The patients' ages ranged from 34 weeks (in utero) to 41 years; their clinical and neuroanatomical characteristics encompassed the entire spectrum of the malformation. Clear visualization of the greatly enlarged posterior fossa, Dandy-Walker cyst, and absence of the inferior vermis established the pathological diagnosis and excluded other structural defects. In 3 patients, MR demonstration of the aqueduct and evidence of pressure on adjacent tissue aided in the surgical planning for ventricular decompression. The MR scan is a significant advancement in the radiological diagnosis of the Dandy-Walker malformation. The major technical advantage of the scan consists in its ability to delineate intracranial morphology in multiple planes.

Adult↗
PubMedDate not supplied

[Sickness, Healing, and Health Services: social representations, practices, and demands among the Baníwa].

The research for this paper was conducted in São Gabriel da Cachoeira, in the northwestern Amazon, with the Baníwa indigenous people, in partnership with indigenous organizations, seeking to understand the relations among the group's cosmology, their system of representations of sickness and healing practices, and their transformation through inter-ethnic contact. The recording of myths showed the origin of the diseases and demonstrated the existence of several traditional categories of sickness, guiding traditional healing practices and the incorporation of biomedical knowledge. The Baníwa's cosmology operates like a reception system for biomedical information, which the people grasp according to the logic of mythical thought. Similar cognitive strategies are used to generate the demands that indigenous leaders submit to the Health Councils and Health Services.

Brazil↗
PubMedDate not supplied

Mathematical modeling of phosphorus losses from land application of hog and cattle manure.

Mathematical models may provide a means to estimate phosphorus (P) losses from land application of manure. Phosphorus losses typically occur during brief episodes of runoff and erosion. Models must be able to simulate P losses during these episodes by representing the basic chemical, physical, and biological processes by which these losses occur. The mathematical model ecosys combines dynamic distributed flow of solutes and nonsolutes through runoff and erosion with convective-dispersive transport of solutes, and both biologically and thermodynamically driven transformations between solutes and nonsolutes. This model was tested against P lost in runoff, erosion, and leachate measured during 90 min of controlled rainfall at 65 mm h(-1) on soils from six sites at which different rates of manure had been applied over the previous 3 to 6 yr. Transport and transformation kinetics in the model enabled it to simulate changes of dissolved inorganic phosphorus (DIP) in runoff from >1.0 to <0.05 mg L(-1) and changes of total phosphorus (TP) in sediment from 15 to 3 mg L(-1) measured during controlled rainfall on soils with diverse P contents. Results from 60-yr model runs using these kinetics with different application rates of cattle manure indicated that (i) a positive interaction exists between annual rainfall and application rate on P losses and (ii) rates greater than 30 Mg ha(-1) yr(-1) would cause TP concentrations in water leaving the site to rise above acceptable limits. The interaction between rainfall and rate suggests that P losses from manure application at any site should be assessed under the upper range of likely rainfall intensities.

Agriculture↗
PubMedDate not supplied

A visual fuzzy cluster system for patient analysis.

A visual fuzzy cluster (VFC) system is developed to assist physicians in interactively detecting and refining cluster partitions for patients with acute upper respiratory infections. The VFC system assists physicians in discovering relationships among patients by applying a fuzzy cluster algorithm to analyse a case base of patient findings. The algorithm discovers similarities among patients, while at the same time identifying atypical patients. The system visually presents the fuzzy cluster solutions on a three-dimensional animated display. Physicians then interactively manipulate icons representing patients to explore and refine the fuzzy cluster solution. Initial experiences with the VFC prototype are encouraging and support the claims that the system improves physician understanding and allows physicians to take advantage of visual recognition and manipulation skills to define and label patient groupings. The resulting labels and cluster centres or prototypes offer insight into the set of patient features that best discriminate between groups.

Algorithms↗