ABSTRACT
Dry skin symptoms such as scaling and itching are often treated with lipophilic moisturizers. The aim of this study was to investigate the effect of lipophilic moisturizers on the stratum corneum (SC) ultra-structure and lipid organization. Lipophilic moisturizers were applied on the forearms of 4 healthy volunteers for 3 h. Subsequently, the application sites were tape stripped, and selected tape strips prepared for Freeze Fracture Electron Microscopy (FFEM), a method to visualize the SC intercellular lipid parallel to the skin surface. To investigate the effect of lipid moisturizers on the lipid lamellae, isolated SC was pretreated with the lipophilic moisturizers for 24 h prior to performing small angle X-ray diffraction (SAXD) measurements. Additionally, the lipid organization of mixtures prepared with ceramides, cholesterol, free fatty acids and lipophilic moisturizer in a 2:1:1:1 molar ratio were studied using SAXD. The FFEM data (in vivo) as well as the SAXD data (in vitro) show that the lipophilic moisturizers do not change the lipid lamellar organization in the SC. Addition of 20% m/m lipophilic moisturizer to the ceramide:cholesterol:free fatty acids mixture did not inhibit the formation of the long periodicity phase, the characteristic lamellar phase in the SC, even though there was clear evidence that two of the three moisturizers were at least partially incorporated in the long periodicity phase. Concluding, all findings suggest that the lipophilic moisturizers investigated in this study do not drastically change the lamellar organization of the SC intracellular lipid matrix, but that the moisturizers form separate domains in the SC, as was visualized by FFEM.
Subject(s)
Emollients/pharmacology , Epidermis/drug effects , Lipid Metabolism , Stearic Acids/pharmacology , Emollients/chemistry , Epidermis/chemistry , Epidermis/ultrastructure , Freeze Fracturing , Humans , In Vitro Techniques , Lipids/chemistry , Microscopy, Electron , Stearic Acids/chemistry , X-Ray DiffractionABSTRACT
Absorbed doses to family members of patients treated with (131)I were measured using thermoluminescent dosimeters worn on the chest. Twenty-two patients with thyroid cancer were hospitalized for 2 d for treatment with 3,700-7,400 MBq, and 18 hyperthyroid patients were treated on an outpatient basis with 200-600 MBq. Doses were measured over periods of 15-21 d following the administration of radioiodine in 35 partners and 38 children, aged 4 mo to 25 y. These results were correlated with dose rate measurements performed with an ionization chamber, and residual thyroid uptake was assessed by scintigraphy over the same period. In the cancer group, the residual activity in thyroid remnants was less than 50 MBq in all cases at day 4 following treatment and decayed with a mean half-life of 2.2 (SD: 0.8) d. The dose measured with thermoluminescent dosimeters was lower than 0.5 mSv in all partners and children. In the hyperthyroid group, the effective half-life averaged 6.2 (SD: 1.2) d. The median of the doses measured in partners and children were 1.04 mSv (range: 0.05-5.2) and 0.13 mSv (range: 0.04-3.1), respectively. Fifteen children (88%) received less than the dose constraint of 0.5 mSv. The ICRP recommend an annual limit of 1 mSv for the members of the public. In addition, dose constraints (for example: 0.5 mSv) should be complied with whenever possible. The recommended dose limits are generally well met among family members of patients treated with 1311 for cancer. The higher doses measured in hyperthyroid patients, compared to thyroid cancer patients, relate to a higher (131)I retention by the gland and justify more extended and stringent restriction periods, based on residual thyroid activity.
Subject(s)
Hyperthyroidism/radiotherapy , Iodine Radioisotopes/pharmacokinetics , Iodine Radioisotopes/therapeutic use , Thermoluminescent Dosimetry/methods , Thyroid Neoplasms/radiotherapy , Adolescent , Adult , Aged , Child , Child, Preschool , Female , Humans , Infant , Iodine Radioisotopes/analysis , Male , Middle Aged , Nuclear Family , Prospective Studies , Spouses , Time FactorsABSTRACT
To deliver optimal radioiodine activity in hemodialyzed patients with thyroid carcinoma, the behavior of radioiodine was followed during six treatments. During hemodialysis, blood activity decreases with a half-life of 3.4 +/- 0.5, (1SD) h. The whole body dose was calculated from the total activity determined during 10 days after 131I administration. A reasonable strategy may consist in delivering 25% of the currently prescribed activity (925 MBq-25 mCi) and to perform the first dialysis session after 24 h to reduce total body irradiation.