Quantitation of total protein deposits on contact lenses by means of amino acid analysis.

PURPOSE: This study was done to characterize and quantify the protein deposits on worn contact lenses and to measure the residual deposits after extraction in 2% sodium dodecyl sulfate and the total protein deposits on worn vifilcon, atlafilcon, and tefilcon lenses (Food and Drug Administration Types IV, II, and I, respectively). METHODS: Contact lens extracts were separated with gel electrophoresis, and the amount of protein was estimated after silver staining and densitometry. To determine the residual deposits, the contact lenses were hydrolyzed, and amino acid analysis was carried out by reverse-phase high-performance liquid chromatography after precolumn derivatization with phenylisothiocyanate. Refinement of the hydrolysis conditions was undertaken to minimize interference by the lens polymers. RESULTS: The extraction removed only approximately 25% of the protein deposits. Mild hydrolytic conditions, 20 hr in 6 N HCl at 105 degrees C, were found to cause minimal polymer interference. Of the 350, 10, and 20 micrograms of protein typically determined on whole vifilcon, atlafilcon, and tefilcon lenses, the polymers were estimated to account for 4, 0.5, and less than 0.4 micrograms, respectively. CONCLUSIONS: Hydrolysis of worn contact lenses with subsequent amino acid separation can be applied to determine the total protein deposits without the uncertainty inherent in extraction of the deposits.

Interaction of plasma proteins with heparinized gel particles studied by high-resolution two-dimensional gel electrophoresis.

In order to further the understanding of protein-surface interactions in the coagulation system, we have chosen to study plasma protein adsorption onto heparin-immobilized surfaces. Heparin-binding proteins are abundant in plasma: a search of amino acid sequences revealed that many plasma proteins have possible heparin binding sites. Plasma protein adsorption to the heparinized surfaces is monitored by a novel technique in which the solution depletion of proteins is analytically determined using quantitative two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). This method enables simultaneous, quantitative detection of the majority of plasma proteins before, during, and after their adsorption onto high surface area adsorbents. Using computerized densitometry of silver-stained 2-D PAGE gels, the amount of each protein can be determined from the integrated optical density of each protein "spot." Kinetics of adsorption and adsorption isotherms of four important heparin binding proteins, antithrombin III (ATIII), complement factor C3 (C3), apolipoprotein AI (Apo-AI) and apolipoprotein AIV (Apo-AIV) are reported in this paper. From the adsorption isotherms, the apparent binding constants of each protein-immobilized heparin complex, Ka, were calculated. The surface binding constants were of the same order of magnitude as the respective solution binding constants in the literature. The surface binding constants followed the same order as the respective solution binding constants: Ka (ATIII) greater than Ka (Apo-AIV) greater than Ka (C3) greater than Ka (Apo-AI), indicating that protein binding to the immobilized heparin used is not essentially different from solution binding.

Experimental investigations on sensitivity to nickel present in alloys used in dentistry carried out on guinea pigs previously sensitized to this metal.

Experimental investigation on sensitivity to nickel present in dental alloys has been carried out on guinea pigs previously sensitized to this metal. The metal plates containing nickel have been sutured to the oral mucosa in such a way that condition of alloys contact with mucosa were possible similar to those present in the mouth of the patient wearing fixed prosthesis. The results of macro and micro examination has not shown any morphological differences between experimental and control material.

Correlation of field injuries and GM hybrid III dummy responses for lap-shoulder belt restraint.

Simulated frontal, lap-shoulder belted, barrier impact tests were performed using a Volvo sedan and General Motors Hybrid III anthropomorphic test dummy. Swedish field accident injury data for this vehicle are available from another published study. For the purpose of this program, the injuries were logically subdivided into four body regions: head, neck, thorax, and lower torso. The Hybrid III has instrumentation in each of these regions. The results of three replicated tests at barrier equivalent velocities of nominally 32 and 48 km/h are discussed in terms of the field injuries, thereby providing a basis for more intelligent interpretation of future Hybrid III test results.

Crash test dummy lower leg instrumentation for axial force and bending moment.

Instrumented anthropomorphic dummy surrogates of humans have been used in automobile occupant crash protection research and development programs for many years. Lower leg instrumentation provides the safety engineer with a valuable tool for gaining otherwise unavailable insights into occupant restraint system performance. Instrumentation described in this paper constitutes an advancement of the state of the art of dummy test technology. A more comprehensive study of crash victim leg loadings is possible with only the traditional femur (upper leg) axial force transducer. Each lower leg has five electrical resistance strain gage circuits to monitor orthogonal bending moments and axial force. Stress analysis and Wheatstone bridge theories are combined in the paper to define strain gage locations and predict transducer sensitivities. Transducer fabrication and calibration precedures are also discussed.

An Assessment of Compressive Neck Loads Under Injury-Producing Conditions.

Injury reference curves for axial compressive forces on the neck were derived from impact tests of a spring-loaded tackling block on football helmets. Results suggest that helmets, especially those with resilient liners, reduce these forces.

A new skin protecting ointment against acrylic resins.

In order to protect the hands of dentists, dental technicians and dental nurses from direct contacts with acrylic monomer, a new type of protective monoglyceride containing ointment has been introduced. The monoglyceride-based ointment was found to prevent penetration of the monomeric part of an autopolymerising acrylic resin and was also shown to have significantly smaller decreasing influence on the ability to manipulate instruments and materials than a compared silicone-based ointment. Furthermore, even with addition of 1% by volume of the monoglyceride-based ointment there was no marked influence on the mechanical properties (elastic modulous and ultimate tensile strength) of an investigated acrylic tray material.