The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.

Journal Article↗

PubMedDate not supplied

Psychoendocrine study of adaptation in young hemophiliacs.

Explore the source record for details and available documents.

17-Hydroxycorticosteroids↗

PubMedDate not supplied

Circulating testosterone levels and aggression in adolescent males: a causal analysis.

Empirical analyses conducted within a causal-analytic framework (path analysis) on a sample of normal adolescent human males suggested that circulating levels of testosterone in the blood had a direct causal influence on provoked aggressive behavior (self-reports): A high level of testosterone led to an increased readiness to respond vigorously and assertively to provocations and threats. Testosterone also had an indirect and weaker affect on another aggression dimension: High levels of testosterone made the boys more impatient and irritable, which in turn increased their propensity to engage in aggressive-destructive behavior. Two somewhat parallel dimensions of behavior, intermale and irritable aggression, have been identified in animal research to be under testosterone control.

Adolescent↗