Lösungsbeispiel "pur" oder "angereichert"? Bedingungen und Effekte erfolgreichen Lernens mit einem komplexen Lösungsbeispiel im Bereich empirischer Forschungsmethoden und Statistik.

Starting from problems of knowledge application in the domain of empirical re-search methods and findings from a field study on example-based learning in this domain, a complex worked-out example was employed under experimental conditions. The completeness of the information provided in the example (no gaps vs. gaps) and the provision of questions of understanding (no questions vs. questions) was varied, that is a 2×2-factorial design was used. For all conditions, a distinct learning progress could be achieved by employing the complex worked-out example. However, learning outcomes were neither fostered by the gaps nor by the questions of understanding. The instructional means also had no influence on cognitive load and on motivational aspects. However, various characteristics of the students proved to be important influencing factorsAusgehend von Problemen der Wissensanwendung im Bereich empirischer Forschungsmethoden und den Befunden einer Feldstudie zum beispielbasierten Lernen in diesem Gebiet wurde ein komplexes Lösungsbeispiel unter experimentellen Bedingungen eingesetzt. Variiert wurden die Vollständigkeit der bereit gestellten Beispielinformation (keine Lücken vs. Lücken) und die Vorgabe von Verständnisfragen (keine Fragen vs. Fragen), d.h. es lag ein 2×2-faktorielles Design vor. Über alle Bedingungen hinweg konnte durch Einsatz des komplexen Lösungsbeispiels ein deutlicher Lernfortschritt erzielt werden. Lücken und Verständnisfragen hatten jedoch keinen Einfluss auf den Lernerfolg. Auf die kognitive Belastung und auf motivationale Aspekte wirkten sich beide Maßnahmen ebenfalls nicht aus. Verschiedene Merkmale der Studierenden erwiesen sich jedoch als wichtige Einflussgröße

Function of N-terminal import signals in trypanosome microbodies

AbstractThe glycosomes of trypanosomes are related to eukaryoticperoxisomes. For many glycosomal and peroxisomal proteins, a C-terminal SKL-like tripeptide known as PTS-1 serves as the targeting signal. For peroxisomes, a second N-terminal signal (PTS-2) was demonstrated on rat 3-ketoacyl-CoA thiolase. Several glycosomal proteins do not bear a PTS-1. One such protein, fructose bisphosphate aldolase, has a PTS-2 homology at its N-terminus. To find out whether the PTS-2 pathway exists in trypanosomes, we expressed chloramphenicol acetyltransferase fusion proteins bearing N-terminal segments of either rat thiolase or trypanosome aldolase. The mammalian PTS-2 clearly mediated glycosomal import. The aldolase N-terminus mediated import with variable efficiency depending on the length of the appended sequence. These results provide evidence for the existence of the PTS-2 pathway in trypanosomes

Estrogen metabolite ratio: Is the 2-hydroxyestrone to 16α-hydroxyestrone ratio predictive for breast cancer?

Experimental studies have shown that two main estrogen metabolites hydroxylated by CYP1A1 and CYP1B1 in the breast differentially affect breast cell proliferation and carcinogenesis. Although 16α-hydroxyestrone (16αOHE1) exerts estrogenic activity through covalent estrogen receptor (ER) binding, 2-hydroxyestrone (2OHE1) presumably has antiestrogenic capabilities. The ratio of 2OHE1 to 16αOHE1 represents the relative dominance of one pathway over the other and is believed to be modifiable by diet. It was hypothesized that women with or at high risk of breast cancer have a lower estrogen metabolite ratio (EMR) compared with women without breast cancer. We conducted a systematic review on the EMR as a predictor for breast cancer. A total of nine studies (six prospective and three retrospective) matched our inclusion criteria, comprising 682 premenopausal cases (1027 controls) and 1189 postmenopausal cases (1888 controls). For the highest compared with the lowest quantile of urinary EMR, nonsignificant associations suggested at best a weak protective effect in premenopausal but not in postmenopausal breast cancer (range of odds ratios: 0.50–0.75 for premenopausal and 0.71–1.31 for postmenopausal). Circulating serum/plasma EMR was not associated with breast cancer risk. Associations were inconclusive for receptor subtypes of breast cancer. Uncontrolled factors known to be involved in breast carcinogenesis, such as 4-hydroxyestrone (4OHE1) concentration, may have confounded results for EMR. Results of the prospective studies do not support the hypothesis that EMR can be used as a predictive marker for breast cancer risk. Future research should concentrate on profiles of estrogen metabolites, including 4OHE1, to gain a more complete picture of the relative importance of single metabolites for breast cancer

Strategies for feeding the world more sustainably with organic agriculture

The authors are grateful for the inputs from Caterina Batello, Jan Breithaupt, Carlo Cafiero, Marianna Campeanu, Reto Cumani, Rich Conant, Piero Conforti, Marie-Aude Even, Karen Franken, Andreas Gattinger, Pierre Gerber, Frank Hayer, Jippe Hoogeven, Stefan Hörtenhuber, Mathilde Iweins, John Lantham, Robert Mayo, Eric Meili, Soren Moller, Jamie Morrison, Alexander Müller, Noemi Nemes, Monica Petri, Tim Robinson, Nicolas Sagoff, Henning Steinfeld, Francesco Tubiello, Helga Willer, and thank Robert Home for checking the language. KHE gratefully acknowledges funding from ERC-2010-Stg-263522 (LUISE). The input of PS contributes to the DEVIL project (NE/M021327/1), funded under the Belmont Forum / FACCE-JPI. This paper contributes to the Global Land Project (www.globallandproject.org). The authors acknowledge funding for open access publication by the Institute of Environmental Decisions, Federal Institutes of Technology, Zurich.Peer reviewedPublisher PD

Age Affects Quantity but Not Quality of Antibody Responses after Vaccination with an Inactivated Flavivirus Vaccine against Tick-Borne Encephalitis

The impairment of immune functions in the elderly (immunosenescence) results in post-vaccination antibody titers that are significantly lower than in young individuals. It is, however, a controversial question whether also the quality of antibodies declines with age. In this study, we have therefore investigated the age-dependence of functional characteristics of antibody responses induced by vaccination with an inactivated flavivirus vaccine against tick-borne encephalitis (TBE). For this purpose, we quantified TBE virus-specific IgG and neutralizing antibody titers in post-vaccination sera from groups of young and elderly healthy adults and determined antibody avidities and NT/ELISA titer ratios (functional activity). In contrast to the quantitative impairment of antibody production in the elderly, we found no age-related differences in the avidity and functional activity of antibodies induced by vaccination, which also appeared to be independent of the age at primary immunization. There was no correlation between antibody avidity and NT/ELISA ratios suggesting that additional factors affect the quality of polyclonal responses, independent of age. Our work indicates that healthy elderly people are able to produce antibodies in response to vaccination with similar avidity and functional activity as young individuals, albeit at lower titers

Highly sensitive real-time PCR for specific detection and quantification of Coxiella burnetii

BACKGROUND: Coxiella burnetii, the bacterium causing Q fever, is an obligate intracellular biosafety level 3 agent. Detection and quantification of these bacteria with conventional methods is time consuming and dangerous. During the last years, several PCR based diagnostic assays were developed to detect C. burnetii DNA in cell cultures and clinical samples. We developed and evaluated TaqMan-based real-time PCR assays that targeted the singular icd (isocitrate dehydrogenase) gene and the transposase of the IS1111a element present in multiple copies in the C. burnetii genome. RESULTS: To evaluate the precision of the icd and IS1111 real-time PCR assays, we performed different PCR runs with independent DNA dilutions of the C. burnetii Nine Mile RSA493 strain. The results showed very low variability, indicating efficient reproducibility of both assays. Using probit analysis, we determined that the minimal number of genome equivalents per reaction that could be detected with a 95% probability was 10 for the icd marker and 6.5 for the IS marker. Plasmid standards with cloned icd and IS1111 fragments were used to establish standard curves which were linear over a range from 10 to 10(7 )starting plasmid copy numbers. We were able to quantify cell numbers of a diluted, heat-inactivated Coxiella isolate with a detection limit of 17 C. burnetii particles per reaction. Real-time PCR targeting both markers was performed with DNA of 75 different C. burnetii isolates originating from all over the world. Using this approach, the number of IS1111 elements in the genome of the Nine Mile strain was determined to be 23, close to 20, the number revealed by genome sequencing. In other isolates, the number of IS1111 elements varied widely (between seven and 110) and seemed to be very high in some isolates. CONCLUSION: We validated TaqMan-based real-time PCR assays targeting the icd and IS1111 markers of C. burnetii. The assays were shown to be specific, highly sensitive and efficiently reproducible. Cell numbers in dilutions of a C. burnetii isolate were reliably quantified. PCR quantification suggested a high variability of the number of IS1111 elements in different C. burnetii isolates, which may be useful for further phylogenetic studies

Do alpine skiers and snowboarders wear protective equipment more often after an accident?

Questions under study/principles: Analysis of changes in the behaviour of wearing protective equipment by alpine skiers and snowboarders after injury, performed at a level I trauma centre in Switzerland. Methods: We present a study, using a standardised questionnaire, assessing behaviour on ski slopes by adult patients admitted between Oct 2007 and April 2008. Patients were re-interviewed after the 2008/2009 season. McNemar tests were used to analyse differences in protective clothing wearing rates between the two seasons. Multiple logistic regression with age, gender and injury severity score (ISS) as predictors, was used to compare findings in those who started wearing protective equipment and those who did not. Results: A total of 104/132 patients from the 2007/2008 season were questioned about wearing protective equipment in 2008/2009. 20 patients could not be reassessed (7 declined, 13 had abandoned winter sports). A total of 84 patients were reassessed (61 alpine skiers and 23 snowboarders). The median age of participants was 39 years and 70.2% were male. Helmet and back protector wearing rates increased from 40.5% to 78.6% (p <0.001) and from 14.3% to 23.8% (p = 0.021), respectively. Snowboarders more than doubled their helmet wearing rate (39.1% to 82.6%, p = 0.002). Skiers showed a trend towards doubling their back protector wearing rate (6.6% to 14.8%, p = 0.063). Younger skiers started wearing back protectors more often than older skiers. Conclusions: Sustained injury might provide skiers and snowboards with a potent trigger to change their attitude towards the use of protective equipment. The psychological processes influencing the use of protective equipment require further investigation