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In surgical refractive interventions over-correction or under-correction still occur in 10-15 % of cases. Improved outcomes could be achieved by incorporating patient-specific corneal biomechanics into surgical planning. As a first step, this study mechanically characterizes and numerically simulates corneal lenticules harvested during a refractive intervention called Corneal Lenticule Extraction for Advanced Refractive Correction (CLEAR). These human corneal lenticules were mechanically tested in uniaxial extension in nasal-temporal and 45 deg orientations. An HGO material model that accounts for the unique collagen arrangement of the human cornea was developed and used to identify the material parameters using a finite element model of the experimental setup. The material parameters that best represent the experimental force/displacement were obtained by parameter estimation using Bayesian optimization. The uniaxial experiments performed on 3 patients did not show distinctive differences in orientation. The estimated material parameters fit well with the experimental data, representing a promising material model. In the future, Brillouin measurements will be performed on the CLEAR patients before lenticule extraction so that material parameters can be estimated in vivo, providing the surgeon with a patient specific-surgical planning tool.

Assessments were made of 945 consecutive hospital patients with regard to a relation between borderline low thyroid function (recognised by a slightly raised thyroid stimulating hormone), thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid stimulating hormone of 4.0 mU/l or over had a higher prevalence of coronary heart disease than did age-matched controls, and this difference was significant in women. The excess of coronary heart disease was not explained by an excess of other risk factors such as a high cholesterol, hypertension, smoking, and diabetes. Women with thyroid antibodies had a slightly higher prevalence of coronary heart disease despite the unexpected finding of a lower serum cholesterol. The data point to an association between borderline thyroid function and autoimmunity and coronary heart disease which is not mediated through a raised serum cholesterol. [ABSTRACT FROM PUBLISHER]

1 The effect of different combinations of liver microsomal enzyme inducing drugs on thyroidal hormone steady state concentrations was investigated. Three groups of healthy volunteers were given daily either antipyrine 1200 mg together with phenobarbitone 100 mg, antipyrine 1200 mg combined with rifampicin 600 mg or rifampicin 600 mg alone for a period of 14 days. 2 Before and after each treatment the total body clearance of antipyrine, gamma-glutamyl transferase (gamma- GT), 6 beta-OH-cortisol as in vivo parameters of liver microsomal enzyme activity were measured. In addition, thyroxine (T4), free thyroxine (FT4), T3 resin uptake, tri-iodothyronine (T3) reverse T3 (rT3) and TSH were estimated. 3 After rifampicin administration there was a 60% increase in antipyrine clearance while following combinations of antipyrine-phenobarbitone or antipyrine-rifampicin an 80% and 128% increase respectively occurred. 4 A marked decrease of T4, FT4 and rT3 was seen in all groups while T3 remained stable in all groups investigated. This effect may be partly due to an increase in extrathyroidal metabolism of T4 as found previously by a kinetic turnover study using 125I-T4. It also depends on the extent of the liver microsomal enzyme inducing capacity rather than on the nature of the drugs used. The striking disparity of liver enzyme induction of T4 and rT3 disposal on the one hand and T3 metabolism on the other is a unique phenomenon whose pathogenesis is not clear at the present time. [ABSTRACT FROM AUTHOR]