The thermal conductivity of cortical and cancellous bone.

Surgical interventions close to vulnerable structures, such as nerves, require precise handling of surgical instruments and tools. These tools not only pose the risk of mechanical damage to soft tissues, but they also generate heat, which can lead to thermal necrosis of bone or soft tissues. Researchers and engineers are trying to improve those tools through experimentation and simulations. To simulate temperature distributions in anatomical structures, reliable material constants are needed. Therefore, this study aimed at investigating the thermal conductivity of cortical and cancellous bone. Accordingly, a custom-made steady-state experimental setup was designed and validated. 6 bovine and 3 human cortical bone samples, as well as 32 bovine cancellous bone samples, with variable bone volume fraction were tested. The cancellous bone samples were scanned by micro-computed tomography (µCT) and micro-finite element (µFE) voxel models were created to calculate iteratively the thermal conductivity of the bone marrow. The experimental results provided 0.64 ± 0.04 W/mK for bovine cortical bone and 0.68 ± 0.01 W/mK for human cortical bone. A linear dependency of thermal conductivity on bone volume fraction was found for cancellous bone [R-square (R2) = 0.8096, standard error of the estimates (SEE) = 0.0355 W/mK]. The thermal conductivity of the bone marrow was estimated to be 0.42 ± 0.05 W/mK. These results will help to improve thermal finite element simulations of the human skeleton and aid the development of new surgical tools or procedures.

Comparison of two formulations of cyclosporin A in the treatment of severe atopic dermatitis. Aa double-blind, single-centre, cross-over pilot study.

BACKGROUND: Cyclosporin A (CsA) has been shown to be highly effective in the therapy of atopic dermatitis (AD). However, little information exists on the treatment of AD patients with Sandimmun Neoral(R) (Neoral), a microemulsion of CsA with improved pharmacokinetic properties in comparison to Sandimmun(R). OBJECTIVE: We have compared the efficacy and tolerability of Sandimmun and Neoral. METHODS: In a randomised, monocentric, double-blind, cross-over pilot study (n = 14), each formulation was administered for 8 weeks, followed by switching to the other treatment group for another 8 weeks. RESULTS: After 2 weeks of therapy, the improvement under Neoral therapy was significantly higher than with Sandimmun (disease activity p = 0.047; extent of disease p = 0.016). In contrast, after 8 weeks of therapy, both formulations yielded similar improvement in the patients' condition. CONCLUSION: While both formulations are effective and well tolerated in the treatment of severe AD, Neoral may have a faster onset of action and higher initial efficacy, which makes it an adequate replacement for Sandimmun.

Treatment of onychomycosis with terbinafine.

An open multicentre trial was conducted by 40 dermatologists in Switzerland involving 188 patients with onychomycosis of either the toenails or fingernails. Of these patients, 145 who had positive microscopy and culture of dermatophyte infection were evaluable: of the dermatophytes identified at the initial visit, 80% were Trichophyton rubrum and 12.4% were T. mentagrophytes. Only the most affected nail was evaluated during the observation period. Daily dosage was 250 mg of terbinafine (Lamisil) orally for up to 6 months. The cure rate (negative microscopy and culture) at the end of treatment was 77% for toenails and 100% for fingernails. A follow-up investigation was made 6 months after the end of treatment: of the 88 patients examined with onychomycosis of the toenail and the 14 with fingernail onychomycosis, 90.9% and 85.7%, respectively, remained free of recurrence. Of the 26 patients who had shown improvement, but not cure, by the end of the treatment period, 15 were clinically and mycologically cured at the time of the follow-up investigation. Terbinafine was generally well tolerated; the most frequent drug-related adverse events were mild-to-moderate gastrointestinal disturbances. Changes in liver or renal biochemical tests were not considered clinically relevant.