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Biomedical subjects

P Steen

Publications and source records attributed to P Steen.

27 records · Page 2Linked to original sources
PubMed1997

[Radial keratotomy: can we predict results?].

PURPOSE: Results after keratotomy may be less than satisfactory. Based on different parameters, we performed statistical efficiency tests in order to improve criteria for good and poor prognosis for the first procedure. MATERIAL AND METHODS: This study used the registries of 155 surgical procedures performed by the same team. Data collected from patient records included degree of myopia, preoperative keratometry, close preoperative pachymetry and postoperative visual acuity. Preoperative factors predicting poor postoperative visual acuity in this population were screened with several statistical tests: one simple test, one two-way (linear or barycentric) test and one principal component factorial test using visual analysis. RESULTS: Prognosis was very different depending on whether myopia was greater than or less than 3.25 diopters. The visual analysis method gave maps capable of screening for prognosis. Results mapping is a new approach. CONCLUSION: Chance of success is greatest in less myopic eyes (< 3.25 diopters) with low keratometry (< 43.5 diopters). Other eyes should not be operated. Easy-to-use maps were obtained and provided hetero unreached prognostic precision. Nevertheless, because of population composition, none of the methods could identify perfectly satisfactory prognosis criteria.

Humans↗
PubMed1996

Evolution of analytical tools by MediQual Systems, Inc.

Over the last two decades purchasers, both private and public, have become increasingly involved in the provision of health care. Their major concern was whether services provided were effective, efficient, and appropriate. Those concerns led to the evolution of analytical tools that do much more than compare averages, which is insufficient to assess outcomes. Analytical tools have evolved in four major areas: 1) case-mix adjustment, 2) comparative data, 3) expanded outcomes, and 4) comprehensive systems. Through 20 years of work, MediQual Systems, Inc., made continuous improvements in its outcomes measuring and reporting systems. These are incorporated in the present version of the Atlas Outcomes system. This work has not occurred in a vacuum, but has been stimulated and encouraged by practical applications such as the Central Florida Healthcare Coalition. This collaborative effort among vendor, provider, and purchaser will move the process to the next step-to build a common platform to analyze the different sets of data.

Health Care Coalitions↗
PubMed1989

Monoclonal antibody markers for amphibian oligodendrocytes and neurons.

Few immunocytochemical probes have been developed for cold-blooded vertebrates, thus hampering analyses of cellular processes in these species. Those developed from mammalian and avian tissue often fail either to react or to show similar specificities in poikilotherms. Therefore, we have begun raising monoclonal antibodies (mabs) in mice against frog and tadpole brain tissue. The following analyses of two of these mabs suggest that these antibodies represent specific probes for frog axons and oligodendrocytes. Mab Olig recognizes all the myelinated axon tracts of the mature frog brain and spinal cord, as well as the tracts of the developing tadpole CNS once they have become myelinated. Axons cut in cross section show characteristic o-shaped staining around individual axons when processed with this antibody. Particularly easy to visualize in the tadpole are immunoreactive cell bodies and processes, seen in continuity with the myelin sheath. Occasionally, in this developing tissue, cells with highly branched processes characteristic of immature oligodendrocytes are observed. No other cells or processes within the brain or spinal cord react with this antibody. Mab Linc stains numerous filaments in all axonal projections. Occasionally, a thin rim of filamentous staining is observed in cell somata, but many regions rich in neuronal somata or dendrites are unreactive to this antibody. This in vivo staining pattern suggests that the Linc antigen is differentially distributed within neurons and exhibits a high concentration in axons. Linc immunoreactivity is robust in the processes of a subpopulation of dissociated tectal cells in culture. These Linc-positive cells are characterized as neurons on morphological criteria. Also, intense Linc immunoreactivity is present in the bundles of retinal axons that extend from retinal explants. Olig immunoreactivity, however, has not been detected in tectal cultures or retinal explants. Improved staining following Triton X-100 treatment of tissue sections suggests that neither of the mabs recognizes lipid antigens and that both are probably localized within the cell cytoplasm. Only the Linc mab reacts on Western blots of denatured brain protein. Linc consistently recognizes two Triton X-100-insoluble proteins with apparent molecular weights of 56 and 58 kD. The epitopes recognized by the Olig and Linc mabs have been surveyed in terms of their resistance to optic nerve crush and their consequent value in studies requiring such procedures. Possible homologies to known cell-type-specific molecules are discussed.

Animals↗