The radiosensitizing effect of platinum nanoparticles in proton irradiations is not caused by an enhanced proton energy deposition at the macroscopic scale.

Objective.Due to the radiosensitizing effect of biocompatible noble metal nanoparticles (NPs), their administration is considered to potentially increase tumor control in radiotherapy. The underlying physical, chemical and biological mechanisms of the NPs' radiosensitivity especially when interacting with proton radiation is not conclusive. In the following work, the energy deposition of protons in matter containing platinum nanoparticles (PtNPs) is experimentally investigated.Approach.Surfactant-free monomodal PtNPs with a mean diameter of (40 ± 10) nm and a concentration of 300 µg ml-1, demonstrably leading to a substantial production of reactive oxygen species (ROS), were homogeneously dispersed into cubic gelatin samples serving as tissue-like phantoms. Gelatin samples without PtNPs were used as control. The samples' dimensions and contrast of the PtNPs were verified in a clinical computed tomography scanner. Fields from a clinical proton machine were used for depth dose and stopping power measurements downstream of both samples types. These experiments were performed with a variety of detectors at a pencil beam scanning beam line as well as a passive beam line with proton energies from about 56-200 MeV.Main results.The samples' water equivalent ratios in terms of proton stopping as well as the mean proton energy deposition downstream of the samples with ROS-producing PtNPs compared to the samples without PtNPs showed no differences within the experimental uncertainties of about 2%.Significance.This study serves as experimental proof that the radiosensitizing effect of biocompatible PtNPs is not due to a macroscopically increased proton energy deposition, but is more likely caused by a catalytic effect of the PtNPs. Thus, these experiments provide a contribution to the highly discussed radiobiological question of the proton therapy efficiency with noble metal NPs and facilitate initial evidence that the dose calculation in treatment planning is straightforward and not affected by the presence of sensitizing PtNPs.

[Public Health as an Applied, Multidisciplinary Subject: Is Research-Based Learning the Answer to Challenges in Learning and Teaching?] / Public Health als anwendungsorientiertes Fach und Multidisziplin ­ "Forschendes Lernen" als Antwort auf die Herausforderungen für Lehren und Lernen?

Public health education aims at enabling students to deal with complex health-related challenges using appropriate methods based on sound theoretical understanding. Virtually all health-related problems in science and practice require the involvement of different disciplines. However, the necessary interdisciplinarity is only partly reflected in the curricula of public health courses. Also theories, methods, health topics, and their application are often taught side-by-side and not together. For students, it can become an insurmountable challenge to integrate the different disciplines ("horizontal integration") and theories, methods, health topics, and their application ("vertical integration"). This situation is specific for education in public health but is representative for other interdisciplinary fields as well. Several approaches are available to achieve the horizontal integration of different disciplines and vertical integration of theories, methods, health topics, and their application. A curriculum that is structured by topics, rather than disciplines might be more successful in integrating different disciplines. Vertical integration can be achieved by research-based learning. Research-based learning places a student-led research project at the centre of teaching. Students choose a topic and a research question, raise their own questions for theories and methods and will hopefully cross the seeming chasm between science and practice. Challenges of research-based learning are enhanced demands on students, teachers and curriculum design.

[Prevalence of type 1 diabetes-specific autoantibodies and of certain HLA patterns in celiac disease]. / Prävalenz Typ 1-Diabetes-spezifischer Autoantikörper und bestimmter HLA-Muster bei Zöliakie.

BACKGROUND AND OBJECTIVE: An association between type 1 diabetes mellitus and celiac disease has been known for some time. One in ten type 1 diabetics have immunological markers for celiac disease (CD). But is there, conversely, an increased risk of CD for diabetics? This study was undertaken to answer this question by determining diabetes-associated antibodies and genetic factors in patients with a gluten-sensitive enteropathy (CD). PATIENTS AND METHODS: 68 patients with CD (48 females and 20 males) were investigated by determining the diabetes-associated serological marker GADA (glutamic acid decarboxylase antibodies). 1A-2A (insulinoma-associated protein 2 antibodies), ICA (Islet cell antibodies) and IAA (insulin autoantibodies). Among this cohort were 60 patients up to the age of 25 years and eight adults (average age 41.7 years). In 36 of these patients the HLA was also determined. RESULTS: GADA was found in 6 patients (9%), 1A-2A in eight (12%) and IAA in 21. ICA were not demonstrated in any. Five of the CD patients were positive for several markers. One child, positive for autoantibodies already had manifest diabetes at the time of investigation. None of the patients with autoantibodies had an abnormal glucose metabolism one year later. HLA-DR3, that occurs in both CD and diabetes, was demonstrated in 78% of the patients with CD. The most common constellation, HLA-DR3-DQ2/HLA-DR7-DQ2, was found in 31%. CONCLUSION: This investigation indicates a genetic association between celiac disease and diabetes. Nonetheless, the risk of developing diabetes mellitus is only minimally higher in patients with CD than in the normal population. Therefore, general screening cannot be recommended at present. Further studies will be needed.

Acute dietary effects on diurnal plasma lipids in normal subjects.

The effects of different dietary carbohydrates and different dietary fats as well as of differently spaced dietary constituents on 24-h plasma free fatty acids and triglycerides were determined in healthy young males. If, in an isocaloric diet containing 15-20% protein, 37% fat and 43--48% carbohydrates, sucrose is compared with glucose, 24-h plasma triglycerides are significantly higher with the former carbohydrate. When palm oil (mainly 16 : 0 fatty acids) is compared with olive oil (mainly 18 : 1 fatty acids), 24-h triglycerides are significantly higher with the latter. If the carbohydrate component of a mixed meal is removed, alimentary lipemia is considerably greater. Our findings supplement long term studies regarding the effect of different dietary fats and carbohydrates on plasma lipids and allow calculation of "upper normal limits" for 24-h plasma triglycerides and free fatty acid patterns on isocaloric diets of "prudent" composition.