University of Marburg

About: University of Marburg is a education organization based out in Marburg, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 23195 authors who have published 42907 publications receiving 1506069 citations. The organization is also known as: Philipps University of Marburg & Philipps-Universität.

Surfactants and experimental irritant contact dermatitis

Abstract: Surface-active agents (surfactants) are characterized by the possession of 2 different moieties, both polar and non-polar regions on the same molecule. Surfactants are broadly classified as anionic, cationic, amphoteric, or non-ionic, according to the nature of the hydrophile yielded in aqueous solution. In currently marketed household, personal, and industrial cleaners, anionic surfactants are the most common class because of their relative ability to solubilize fats and oils, lower the surface tension of aqueous solutions, or form microemulsions. Many surfactants elicit irritant reactions when applied to the skin, partially due to their relative ability to solubilize lipid membranes. Hence, surfactants have become important implements in skin irritation investigations. In general, the physicochemical properties of surfactants are a crucial factor in eliciting skin irritation. Anionic surfactants are broadly accepted as potent irritants to human and animal skin. Cationic surfactants are reputedly at least equally irritating, but more cytotoxic than anionic, while the irritation potential of non-ionic surfactants is considered the lowest. Such classification of innumerable surfactants is convenient and held in high practical esteem. however, the categorization does not permit the exact determination of irritation and cytotoxicity potential of each surfactant. Ranking of surfactant skin irritancy and cytotoxicity obtained by both in vitro and in vivo assays provides a helpful orientation for future work.

Early detection of breast cancer: benefits and risks of supplemental breast ultrasound in asymptomatic women with mammographically dense breast tissue. A systematic review

Abstract: Mammographic screening alone will miss a certain fraction of malignancies, as evidenced by retrospective reviews of mammograms following a subsequent screening. Mammographic breast density is a marker for increased breast cancer risk and is associated with a higher risk of interval breast cancer, i.e. cancer detected between screening tests. The purpose of this review is to estimate risks and benefits of supplemental breast ultrasound in women with negative mammographic screening with dense breast tissue. A systematic search and review of studies involving mammography and breast ultrasound for screening of breast cancer was conducted. The search was performed for the period 1/2000-8/2008 within the data source of PubMed, DARE, and Cochrane databases. Inclusion and exclusion criteria were determined prospectively, and the Oxford evidence classification system for diagnostic studies was used for evidence level. The parameters biopsy rate, positive predictive value (PPV) for biopsy, cancer yield for breast ultrasound alone, and carcinoma detection rate by breast density were extracted or constructed. The systematic search identified no randomized controlled trials or systematic reviews, six cohort studies of intermediate level of evidence (3b) were found. Only two of the studies included adequate follow-up of subjects with negative or benign findings. Supplemental breast ultrasound after negative mammographic screening permitted diagnosis of primarily invasive carcinomas in 0.32% of women in breast density type categories 2-4 of the American College of Radiology (ACR); mean tumor size for those identified was 9.9 mm, 90% with negative lymph node status. Most detected cancers occurred in mammographically dense breast ACR types 3 and 4. Biopsy rates were in the range 2.3%-4.7%, with PPV of 8.4-13.7% for those biopsied due to positive ultrasound, or about one third of the PPV of biopsies due to mammography. Limitations: The study populations included wide age ranges, and the application to women age 50-69 years as proposed for mammographic screening could result in less striking benefit. Further validation studies should employ a uniform assessment system such as BI-RADS and report not only PPV, but also negative predictive value, sensitivity and specificity. Supplemental breast ultrasound in the population of women with mammographically dense breast tissue (ACR 3 and 4) permits detection of small, otherwise occult, breast cancers. Potential adverse impacts for women in this intermediate risk group are associated with an increased biopsy rate.

Alternatively activated macrophages do not synthesize catecholamines or contribute to adipose tissue adaptive thermogenesis

Abstract: Adaptive thermogenesis is the process of heat generation in response to cold stimulation. It is under the control of the sympathetic nervous system, whose chief effector is the catecholamine norepi ...

Charge carrier mobility in regioregular poly(3-hexylthiophene) probed by transient conductivity techniques: A comparative study

Abstract: The temperature and electric-field dependence of charge carrier mobility has been studied by a conventional time-of-flight technique in chemically purified, low dark conductivity samples of regioregular poly(3-hexylthiophene) Subsequently, the mobility of doping-induced charge carriers has been determined using the technique of charge carrier extraction by linearly increasing voltage in the same samples exposed to air The charge carrier mobility determined by both experimental techniques correspond well to each other at temperatures above $130\phantom{\rule{03em}{0ex}}\mathrm{K}$, indicating that these experimental techniques are mutually consistent The study clearly shows that the typical $\mathrm{log}\phantom{\rule{02em}{0ex}}\ensuremath{\mu}\ensuremath{\propto}\ensuremath{\beta}{E}^{1∕2}$, $\ensuremath{\beta}g0$ Poole--Frenkel-like electric-field dependence of the charge carrier mobility diminishes at temperatures around $250--270\phantom{\rule{03em}{0ex}}\mathrm{K}$, and $\ensuremath{\beta}$ becomes negative at higher temperatures Such negative electric-field dependence of mobility observed by both experimental techniques is attributed to positional disorder in a random-organic dielectric and analyzed in the framework of the disorder formalism Finally, the overall agreement indicates that the mode of charge generation has negligible effect on the temperature- and electric-field dependence of mobility except at the lowest temperatures $(l110\phantom{\rule{03em}{0ex}}\mathrm{K})$, where transit time dispersion of the photogenerated charge carriers probed by the ToF technique is more pronounced

Extracellular vesicle measurements with nanoparticle tracking analysis – An accuracy and repeatability comparison between NanoSight NS300 and ZetaView

Abstract: The expanding field of extracellular vesicle (EV) research needs reproducible and accurate methods to characterize single EVs. Nanoparticle Tracking Analysis (NTA) is commonly used to determine EV ...