Vesicle solubilization by bile salts: comparison of macroscopic theory and simulation.

Lipid metabolism is accompanied by the solubilization of lipid bilayer membranes by bile salts. We use Brownian dynamics simulations to study the solubilization of model membranes and vesicles by sodium cholate. The solubilization pathways of small and large vesicles are found to be different. Both results for small and large vesicles can be compared with predictions of a macroscopic theoretical description. The line tension of bilayer edges is an important parameter in the solubilization process. We propose a simple method to determine the line tension by analyzing the shape fluctuations of planar membrane patches. Macroscopic mechanical models provide a reasonable explanation for processes observed when a spherical vesicle consisting of lipids and adsorbed bile salt molecules is transformed into mixed lipid-bile salt micelles.

Robustness testing of a reversed-phase high-performance liquid chromatographic assay: comparison of fractional and asymmetrical factorial designs.

Robustness tests were performed on a reversed-phase HPLC assay for triadimenol. Different experimental designs were compared. Two-level fractional factorial designs with different resolutions were used to study the influence of procedure-related factors. The factors chromatographic column manufacturer at four levels and instrument at three levels were stepwise included in the study using asymmetrical factorial designs. The significance of the factor effects was determined statistically, using two types of error estimates in the calculation of critical effects, and graphically, by means of half-normal plots. The asymmetrical designs turned out to be an efficient and economic method to examine the influence of factors at different numbers of levels in the robustness testing of analytical methods.

Red thermoluminescence of quartz and its application in dating archaeometallurgical slag.

Slag is often the only relic of early pyrometallurgical processes. In archaeological research information about the age of slag deposits is needed and diflicult to obtain with traditional methods. Thermoluminescence has a great potential in this field, because the smelting process leads to a well defined resetting of the 'Luminescence Clock'. Metallurgical slag generally consists of many components, artificial secondary minerals, e.g. fayalite and glass phases usually being the dominant parts. Primary minerals, called relics, are also components or slag. Such a complex composition leads to large difficulties in palaeodose determation if the bulk slag is used. To overcome these problems defined phases of the slag have been separated. Palaeodose determination has been carried out on separated quartz fractions by 'Single Aliquot Regeneration' procedures using the 620 nm emission. The dose rate was determined by high-resolution gamma spectrometry. Alpha autoradiography was carried out to get information about the distribution of radionuclides. The study includes first dating results.

[Therapy-resistant swelling of the upper eyelid in childhood]. / Therapieresistente Oberlidschwellung im Kindesalter.

HISTORY: Swelling of the upper eyelid in childhood is caused by a variety of diseases and is very often generated by inflammation but orbital tumors should always be considered in the differential diagnostics. METHODS: We report about a 4-year-old girl with a drug-resistant swelling of the upper eyelid and ptosis of the right eye. This case report demonstrates the route from initial clinical examination to diagnosis and additionally reviews the current status of therapeutic options. RESULTS: After magnetic resonance imaging (MRI) and diagnostic excision, Langerhans cell histiocytosis (LCH) could be histologically proven. Visual acuity and levator muscle function improved from 0.5 to 1.25 and from 2 mm to 12 mm, respectively, by amblyopic prophylaxis and immunosuppressive therapy. CONCLUSIONS: Persistent and drug-resistant swelling of the upper eyelid in childhood is also strongly suspicious for tumors. The suspicion of rare orbital tumors in children can be frequently substantiated by MRI. Biopsy and histological diagnosis are essential to plan adequate treatment and to estimate the prognosis. Particularly in Langerhans cell histiocytosis the methods of choice for over 10 years are specific immunochemical procedures (detection of protein s100 and CD1a).

[Ankyloblepharon filiforme adnatum]. / Ankyloblepharon filiforme adnatum.

The ankyloblepharon filiforme adnatum is a congenital eyelid anomaly in which the development of the eyelids is completed but the eyelids are not completely separated at birth. The abnormality can occur as an isolated anomaly, together with other eye diseases or in the context of systemic syndromes. In this case report the current classification and essential diagnostics of AFA will be reviewed.

[Gingival hyperplasia and visual reduction]. / Zahnfleischschwellung und Visusreduktion.

This case report describes the unilateral acute reduction of vision in the right eye of a 48-year-old woman. The patient was otherwise healthy but 2 days previously had suffered from dizziness and blurred vision. Secondary to this, the patient had already been under dental treatment for 1 week due to gingival swelling. At the first examination a macular branch retinal vein occlusion and Roth spots were found in the right eye by indirect ophthalmoscopy. The immediate diagnostic procedure identified aute amyeloid leukemia (AML) as the cause of the vascular pathology. The AML can be manifested in different ways and the retina is involved in approximately 50% of cases. Due to a secondary hyperviscosity syndrome, which is found in approx. 20% of acute leukaemias, symptomatic central vein occlusion or macular branch vein occlusion can occur. Ophthalmic symptoms can be the first and only signs to be detected. Therefore, ophthalmologists should also consider a systemic disease and initiate a clarification. A differential blood count is indispensable. The results usually improve by a rapidly arranged and suitable therapy. Ophthalmological follow-up examinations are imperative as an initiated chemotherapy can also produce ophthalmological side-effects.

[Measurement of the disc area by indirect ophthalmoscopy]. / Flächenbestimmung der Papille mittels indirekter Ophthalmoskopie.

PURPOSE: The aim of this study was to assess the accuracy of measuring the optic disc area by indirect ophthalmoscopy. PATIENTS AND METHODS: In a prospective clinical trial, 57 eyes of 29 subjects (age 57.3+/-12.1 years) were examined. The refractive error was -0.67+/-2.69D (+3.75D to -8D).The vertical and horizontal disc diameters (DD) were measured using a Haag-Streit slit lamp and 60D-, 78D-, 90D-, and Super Field lenses (Volk Optical, Mentor, USA). Afterwards the disc area was calculated by an ellipse formula (horizontal DD x vertical DD x pi/4). The magnification factor given by the manufacturer was taken into account for each lens: 1.15x (60D lens), 0.93x (78D lens), 0.76x (90D lens), and 0.76x (Super Field lens), respectively. As reference for the disc size, the same eyes were examined by HRT II (Heidelberg Engineering, Heidelberg, Germany). Bland-Altman plots were used to assess the agreement between measurements obtained by indirect ophthalmoscopy and HRT. RESULTS: The results of the disc estimate compared with the HRT measurements were as follows: 0.119+/-0.51 mm(2) (60D lens), 0.224+/-0.57 mm(2) (78D lens), 0.10+/-0.51 mm(2) (90D lens), and -0.07 s+/-0.47 mm(2) (Super Field lens). Differences were not statistically significant for the 60D (p=0.083), 90D (p=0.147), or Super Field lenses (p=0.257). However, the difference between the 78D lens and HRT was statistically significant (Student's t-test; P=0.004). CONCLUSION: Measuring the disc size by indirect ophthalmoscopy is possible. The 90D lens showed the smallest and the 78D lens the largest deviation.

[Biomechanical condition of the cornea as a new indicator for pathological and structural changes]. / Biomechanische Zustand der Hornhaut als neuer Indikator für pathologische und strukturelle Veränderungen.

AIM: Several methods permit the measurement of geometric parameters of the cornea, but until now biomechanical conditions of the cornea have been ignored (e.g. in refractive corneal surgery). Besides the geometric condition, biomechanical properties of the cornea have been shown to influence applanation measurement of intra-ocular pressure (IOP) and epidemiological studies have identified corneal thickness as an independent risk factor for the development and progression of glaucoma. The aim of this investigation was to characterize the biomechanical properties of the cornea using the ocular response analyzer (ORA). METHODS: The ocular response analyzer (ORA) is a new method available for non-contact measurement of the biomechanical properties of the cornea. We evaluated the reproducibility of measurements, the difference between static and dynamic factors and the impact of independent factors (e.g. IOP, age, CCT, swelling of the cornea) on 2,500 measurements of corneal hysteresis (CH) and corneal resistance factor (CRF). RESULTS: In a large sample size we observed changes in CH and CRF after refractive surgery procedures (LASIK, UV-A cross-linking, keratoplasty) and in other corneal disorders (keratoconus, corneal dystrophies). CONCLUSIONS: CRF and CH changes may reflect structural changes of the cornea. Thus, the ORA provides valuable information for a better understanding and characterization of the biomechanical condition of the cornea, especially with regard to diseases such as keratoconus and glaucoma.