Biomedical subjects
Publications and source records attributed to F Bigar.
The corneal endothelium of intact donor eyes was evaluated by means of a specular microscope. In a series of 278 corneas, different morphologic changes were found in the endothelium. These changes are described and systematically classified. The findings are analogous to results obtained on experimental animals and with light- and electron-microscopic studies of other authors.
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Experiments were performed to study the fate of corneal grafts sensitized to herpes antigens when grafted to HSV-sensitized hosts. Nonsensitized grafts in systemically sensitized hosts remained clear, whereas all locally sensitized grafts in systemically sensitized hosts became opaque within ten days. The stroma showed severe lymphocytic and plasma cell infiltration and neovascularization. One-half of the corneas from systemically sensitized hosts grafted to eyes previously infected opacified in an accelerated manner. Round cells were found in the stroma and endothelium. The histological reaction in both groups was similar to that found in the immune graft reaction even though the clinical picture was not typical (peripheral and progressive edema with a rejection line). The accelerated reaction was probably related to the presence of virus antigens in graft stroma and subepithelial areas of the graft. The significance of HSV-sensitized donor tissue grafted onto HSV-sensitized hosts is discussed because of its possible implication in tissue transplantation.
Twenty-six of 28 human corneas stored for up to seven days in a simple tissue culture medium (dextran dissolved in tissue culture medium with streptomycin-penicillin mixture) remained clear and thin after keratoplasty. Temperature reversal phenomenon and electron microscopy demonstrated high quality of such tissue after storage. The method is inexpensive, requires limited technical assistance, and provides the surgeon with excellent tissue at regular operation hours.
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BB shots and other spherical foreign bodies produce long chains of rapidly successive echo spikes which gradually decrease in height. These patterns are specific for this type of foreign bodies and allow their reliable detection and accurate localization. A-scan echography has become a very useful addition to X-ray examination in order to determine whether such foreign bodies are intra- or extraocular. Echography also helps to localize such foreign bodies during surgery and to evaluate the posterior segment of the eye in the presence of opaque ocular media (hemorrhages, cataract). Although it is sometimes possible to demonstrate specific B-scan patterns of spherical foreign bodies, A-scan echography is the method of choice since it is faster, more reliable and more accurate.
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Cavernous hemangiomas of the orbit produce echographic A-scan patterns which allow their detection, localization, measurement, and differentiation from all other orbital lesions with a high degree of accuracy. Specific echograms, however, of these tumors can only be obtained with optimized and standardized A-scan instruments providing specific settings of the sensitivity, amplifier characteristics, dynamic range, expansion of the screen display, filtering, etc. When instruments other than these are used, both differentiation and detection of this tumor become difficult or impossible. The more an A-scan instrument differs from the optimized and standardized type, the less successful the diagnosis of cavernous hemangiomas becomes, B-scan techniques add to the A-scan examination by better demonstrating the round shape and the topographic relationship to the globe, the optic nerve and the orbital wall.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.