Evaluation of the new "System Olli 3000" kinetic ultraviolet analyzer for measuring aspartate ana alanine aminotransferase and lactate dehydrogenase activities in serum.
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A new fast kinetic analyzer, System Olli 3000, is evaluated as an instrument for the routine clinical laboratory measurement of the activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase in serum. The System Olli 3000 consists of dispensers for simultaneous multiple dispensing of sample and reagents, incubators, vortex-type shakers, and a photometer with quartz fibre optics connected to a computer, allowing cycling measurements of 24 cuvets 24 times in 2 min. An unique slope search algorithm is described. The system shows a high degree of precision and a wide linearity range; activities of at least 10-fole the normal upper limit for all three of these enzymes can be measured without diluting the serum sample. As many as 380 analyses per hour (including calibration and blanks) can be carried out by one technician. For comparison, enzyme measurements were also made with an LKB 8600 Reaction Rate Analyzer and a Pye Unicam SP 8005 spectrophotometer coupled on-line to an IBM 1800 computer. Results obtained with the different instruments correlated well, especially in the region of main interest, i.e., above the normal upper limit. We conclude that the new instrument has many potentialities in kinetic analyses of nonenzymatic constituents in biological fluids. (+info)
Small-group CME using e-mail discussions. Can it work?
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PROBLEM BEING ADDRESSED: Traditional continuing medical education (CME) approaches do not work well in changing physicians' behaviour, but some promising strategies and technologies might help. Our program sought to meld small-group learning with an Internet e-mail approach. OBJECTIVE OF PROGRAM: In 1994, the Family medicine Education and Research Network (FERN) was developed to support on-line discussion among London, Ont, and area family physicians. To support educational, moderated case discussions using e-mail, FERN Dissemination (FERN-D) was introduced to a subgroup of participants. We hoped to increase awareness and use of evidence-based research in clinical practice and to increase use of Internet-based resources for CME. The target group was family physicians in the London area. MAIN COMPONENTS OF PROGRAM: Forty volunteers were recruited and were e-mailed one case every 2 weeks; 34 completed the study. Each case was followed by further postings and, at the end of 2 weeks, by a summary of the group's discussion. Background material for each case was researched and was evidence-based. Evaluation was conducted using preintervention and postintervention mailed surveys combined with an e-mail feedback questionnaire and a modified focus group. CONCLUSION: On-line case-based discussion is a promising strategy for encouraging family physicians to access current research. More research is needed to determine whether it can be effectively used to change physicians' practice. (+info)
Variability of the relative preference for stimulus orientation and direction of movement in some units of the cat visual cortex (areas 17 and 18).
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1. The responses to visual stimuli of single units in the cortex of cats anaesthetized with pentobarbitone were recorded extracellularly with glass micropipettes. All had receptive field centres more than 5 degrees and most lay between 5 and 20 degrees from the area centralis. Most units were in Area 18 but some were in the corresponding field representation in Area 17. 2. A quantitative method is described in which the visual stimuli (slits or light bars) were presented repetitively by mechanical means in each of four orientations of the stimulus and in two directions of movement for each orientation. The responses were analysed quantitatively and criteria are described for classification of units according to their preference for particular orientations or directions of movement of the stimulus. 3. Some units were studied continuously for up to 2 hr using the quantitative technique. In Area 18, of nineteen units, eighteen showed changes in their preference for direction of stimulus movement and, in seven of eleven units, the orientation preference changed. In Area 17 direction preference changed in eight of nine units and orientation preference in six of seven. In some cases both orientation and direction preference altered. 4. The relationship of these changes to alterations in the 'spontaneous activity' of the cortical units and to variations in the depth of anaesthesia are considered. Neither would appear to be the sole cause of the phenomenon. (+info)
The effect of a chronic lesion in cortical area 17 on the visual responses of units in area 18 of the cat.
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1. Lesions were made in cortical Area 17 (Visual I) of eight cats which were then allowed to recover. 2. During acute experiments between 1 and 11 weeks after the lesion the activity of Area 18 (Visual II) units was recorded and the results were compared with those obtained in normal cats. 3. The receptive fields were similar in size and distribution in the two groups but the lesioned animals had a much higher proportion of units unaffected by a visual stimulus and a higher proportion of the visually responsive units lacked specific direction or orientation preference. 4. Of six units which were tested in Area 18 of cats with lesions five showed variability of their direction or orientation preference with time. 5. The effects described above are most probably due to destruction of the corticocortical pathway which connects Areas 17 and 18. Some units in Area 18 appear to be driven by visual stimuli via their geniculate input alone. The corticocortical (Area 17 to 18) pathway may normally confer additional specificity on some of these units. (+info)
Removal of contrast media by different extracorporeal treatments.
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BACKGROUND: Although the capability of extracorporeal treatments after administration of contrast media to prevent radiocontrast-induced nephropathy is controversial, haemodialysis is performed in many institutions after radiographic procedures. There are conflicting reports on the efficacy of different dialysers and treatment modalities to remove contrast media. METHODS: We compared the contrast medium-removing ability of different extracorporeal treatments in a randomized trial. Thirty-nine patients on chronic renal-replacement therapy or with chronic renal failure were randomized to receive low-flux haemodialysis (Low-HD, n=10), high-flux haemodialysis (High-HD, n=10), online haemodiafiltration (HDF, 10 litre substitution, n=10) and online haemofiltration (HF, 18 litre substitution, n=9) after administration of contrast medium during routine radiological procedures. Plasma concentrations of contrast medium (iopromide or iomeprol) were measured by energy-dispersive X-ray fluorescence analysis. RESULTS: The extraction ratio for contrast media was 0.64+/-0.1 for Low HD (P<0.05 vs. High-HD and vs. HDF), 0.74+/-0.1 for High-HD (P<0.05 vs. HF), 0.81+/-0.1 for HDF (P<0.05 vs HF), and 0.62+/-0.1 for HF. Mean extracorporeal plasma clearances were 82+/-2 for Low-HD (P<0.05 vs. High-HD and vs HDF), 100+/-2 for High-HD, 115+/-4 for HDF (P<0.05 vs. HF), and 86+/-5 ml/min for HF. CONCLUSIONS: We conclude that HDF and High-HD remove contrast media more effectively than Low-HD and HF during the time of each treatment session. However, whether this is also true for the overall elimination of contrast media by these different procedures needs to be addressed in future studies, by a precise assessment of the drug time course after the session. (+info)
On-line identification of sensory systems using pseudorandom binary noise perturbations.
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A technique of on-line identification of linear system characteristics from sensory systems with spike train or analog voltage outputs was developed and applied to the semicircular canal. A pseudorandom binary white noise input was cross-correlated with the system's output to produce estimates of linear system unit impulse responses (UIRs), which were then corrected for response errors of the input transducers. The effects of variability in the system response characteristics and sensitivity were studied by employing the technique with known linear analog circuits. First-order unit afferent responses from the guitarfish horizontal semicircular canal were cross-correlated with white noise rotational acceleration inputs to produce non-parametric UIR models. In addition, the UIRs were fitted by nonlinear regression to truncated exponential series to produce parametric models in the form of low-order linear system equations. The experimental responses to the white noise input were then compared with those predicted from the UIR models linear convolution, and the differences were expressed as a percent mean-square-error (%MSE). The average difference found from a population of 62 semicircular canal afferents was relatively low mean and standard deviation of 10.2 +/- 5.9 SD%MSE, respectively. This suggests that relatively accurate inferences can be made concerning the physiology of the semicircular canal from the linear characteristics of afferent responses. (+info)
Creating the gene ontology resource: design and implementation.
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The exponential growth in the volume of accessible biological information has generated a confusion of voices surrounding the annotation of molecular information about genes and their products. The Gene Ontology (GO) project seeks to provide a set of structured vocabularies for specific biological domains that can be used to describe gene products in any organism. This work includes building three extensive ontologies to describe molecular function, biological process, and cellular component, and providing a community database resource that supports the use of these ontologies. The GO Consortium was initiated by scientists associated with three model organism databases: SGD, the Saccharomyces Genome database; FlyBase, the Drosophila genome database; and MGD/GXD, the Mouse Genome Informatics databases. Additional model organism database groups are joining the project. Each of these model organism information systems is annotating genes and gene products using GO vocabulary terms and incorporating these annotations into their respective model organism databases. Each database contributes its annotation files to a shared GO data resource accessible to the public at http://www.geneontology.org/. The GO site can be used by the community both to recover the GO vocabularies and to access the annotated gene product data sets from the model organism databases. The GO Consortium supports the development of the GO database resource and provides tools enabling curators and researchers to query and manipulate the vocabularies. We believe that the shared development of this molecular annotation resource will contribute to the unification of biological information. (+info)
Accessing heterogeneous sources of evidence to answer clinical questions.
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The large and rapidly growing number of information sources relevant to health care, and the increasing amounts of new evidence produced by researchers, are improving the access of professionals and students to valuable information. However, seeking and filtering useful, valid information can be still very difficult. An online information system that conducts searches based on individual patient data can have a beneficial influence on the particular patient's outcome and educate the healthcare worker. In this paper, we describe the underlying model for a system that aims to facilitate the search for evidence based on clinicians' needs. This paper reviews studies of information needs of clinicians, describes principles of information retrieval, and examines the role that standardized terminologies can play in the integration between a clinical system and literature resources, as well as in the information retrieval process. The paper also describes a model for a digital library system that supports the integration of clinical systems with online information sources, making use of information available in the electronic medical record to enhance searches and information retrieval. The model builds on several different, previously developed techniques to identify information themes that are relevant to specific clinical data. Using a framework of evidence-based practice, the system generates well-structured questions with the intent of enhancing information retrieval. We believe that by helping clinicians to pose well-structured clinical queries and including in them relevant information from individual patients' medical records, we can enhance information retrieval and thus can improve patient-care. (+info)