Color and scent: how single genes influence pollinator attraction

A major function of angiosperm flowers is the recruitment of animal pollinators that serve to transfer pollen among conspecific plants. Distinct sets of floral characteristics, called pollination syndromes, are correlated with visitation by specific groups of pollinators. Switches among pollination syndromes have occurred in many plant families. Such switches must have involved coordinated changes in multiple traits and multiple genes. Two well-studied floral traits affecting pollinator attraction are petal color and scent production. We review current knowledge about the biosynthetic pathways for floral color and scent production and their interaction at the genetic and biochemical levels. A key question in the field concerns the genes that underlie natural variation in color and scent and how such genes affect pollinator preference, reproductive isolation, and ultimately speciation.

X-ray absorption from large molecules at metal surfaces: theoretical and experimental results for Co-OEP on Ni(100)

Metal octaethylporphyrins (M-OEP), M-N(4)C(20)H(4)(C(2)H(5))(8), adsorbed at a metallic substrate are promising candidates to provide spin dependent electric transport. Despite these systems having been studied extensively by experiment, details of the adsorbate geometry and surface binding are still unclear. We have carried out density functional theory calculations for cobalt octaethyl porphyrin (Co-OEP) adsorbate at clean and oxygen-covered Ni(100) surfaces as well as for the free Co-OEP molecule where equilibrium structures were obtained by corresponding energy optimizations. These geometries were then used in calculations of Co-OEP carbon and nitrogen 1s core excitations yielding theoretical excitation spectra to be compared with corresponding K-edge x-ray absorption fine structure (NEXAFS) measurements. The experimental NEXAFS spectra near the carbon K-edge of Co-OEP bulk material show large intensity close to the ionization threshold and a triple-peak structure at lower energies, which can be reproduced by the calculations on free Co-OEP. The experimental nitrogen K-edge spectra of adsorbed Co-OEP layers exhibit always a double-peak structure below ionization threshold, independent of the layer thickness. The peaks are shifted slightly and their separation varies with adsorbate-substrate distance. This can be explained by hybridization of N 2p with corresponding 3d contributions of the Ni substrate in the excited final state orbitals as a result of adsorbate-substrate binding via N-Ni bond formation.

[Experiences and attitudes regarding practice-based clinical trials: results of a survey among German primary care physicians]

OBJECTIVE

Clinical trials are regarded as complex due to the high demands on quality and patient safety and are still exceptional in German primary care. To optimise future trial planning, this study aimed at investigating the barriers and enablers experienced by primary care physicians (PCPs) for trial participation.

METHODS

PCPs were surveyed on 11 regional primary care medical education (CME) events using a standardised questionnaire. Regression analyses were used to identify predictors for future trial participation.

RESULTS

Of 804 invited PCPs, 408 (50.7%) participated in the survey (51 ± 9 years, female 35%). 69% of participants could imagine their participation in a clinical trial. Of 12 potential factors assessed, the final model retained the 2 predictors (OR; CI; P-value) "research questions relevant to practice" (2.25; 1.61-3.14;<0.001) and "new challenges/change from everyday life" (2.24; 1.67-2.97;<0.001). While 58% of participants were principally willing to participate in investigator training courses according to Good Clinical Practice (GCP), only 6% had participated in such training at the time of answering. Short events were preferred. Only 7% were willing to take over at least half of the costs of these courses.

CONCLUSION

To enhance German PCPs motivation to participate in clinical trials, both trials and training courses should be tailored to the needs in the primary care setting.

Self-metalation of 2H-tetraphenylporphyrin on Cu(111): an x-ray spectroscopy study

The bonding and the temperature-driven metalation of 2H-tetraphenylporphyrin (2H-TPP) on the Cu(111) surface under ultrahigh vacuum conditions were investigated by a combination of x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy with density functional theory calculations. Thin films were prepared by organic molecular beam epitaxy and subsequent annealing. Our systematic study provides an understanding of the changes of the spectroscopic signature during adsorption and metalation. Specifically, we achieved a detailed peak assignment of the 2H-TPP multilayer data of the C1s and the N1s region. After annealing to 420 K both XPS and NEXAFS show the signatures of a metalloporphyrin, which indicates self-metalation at the porphyrin-substrate interface, resulting in Cu-TPP. Furthermore, for 2H-TPP monolayer samples we show how the strong influence of the copper surface is reflected in the spectroscopic signatures. Adsorption results in a strongly deformed macrocycle and a quenching of the first NEXAFS resonance in the nitrogen edge suggesting electron transfer into the LUMO. For Cu-TPP the spectroscopic data indicate a reduced interaction of first-layer molecules with the substrate as demonstrated by the relaxed macrocycle geometry.

[HeiCare®: a project aiming to improve medication communication across health care sectors]

BACKGROUND AND OBJECTIVE

Changes between health care sectors represent a critical phase in long-term pharmacotherapy. The aim of the Hei CARE(®) project was to close the communication gap at the interface between primary care physicians (PCP), hospital physicians and patients, and to improve quality and safety of pharmacotherapy.

METHODS

Physicians who enrolled patients with long-term pharmacotherapy were able to participate in the Hei CARE(®) project. After enrolment the patient's medication was entered in the internet-based medication knowledge data base AiD PRAXIS and checked for medication interactions and optimized if necessary. At hospitalisation medication was transferred electronically to the hospital (AiD KLINIK(®)) and on discharge integrated in the discharge letter and faxed to the primary care physician (PCP). The project was evaluated using quantitative and qualitative methods. Hei CARE(®) -cases, in which medication was transferred electronically as planned, were compared with the other cases. PCPs' experiences were collected in focus groups.

RESULTS

One thousand and three chronically ill patients of 56 primary care practices participated. 259 patients were hospitalized between October 2005 and March 2009 of which entrance and discharge medication were transferred both ways via the electronic prescribing platform in 67 cases. The number of changes in medication was reduced in comparison to the other cases. Participating PCPs reported positive changes through Hei CARE(®) as well as further potential for optimizing communication across health care sectors.

CONCLUSION

Use of a common internet-based medication knowledge data base (Hei CARE(®) ) in both health care sectors reduced the number of changes in pharmacotherapy. Seamless care in chronically ill patients was thereby improved. The project also demonstrated that improving communication across health care sectors is a slow process.

[Development, factor-analytical control and psychometric evaluation of a questionnaire on specialty choices among medical students]

AIM OF THE STUDY

A questionnaire was developed and validated which assesses factors influencing career choices of medical students and their perception of possibilities in general practice.

METHODS

The first questionnaire version, which was developed based on a systematic literature review, was checked for comprehensibility and redundancy using concurrent think aloud. The revised version was filled out by a pilot sample of medical students and the factor structure was assessed using principal component analysis (PCA). The final version was filled out in an online survey by medical students of all 5 Medical Faculties in the federal state of Baden-Wuerttemberg. The factor structure was validated with a confirmatory factor analysis (CFA). Reliability was assessed as internal consistency using Cronbach's α.

RESULTS

The questionnaire comprises 2 parts: ratings of (A) the individual importance and of (B) the possibilities in general practice on 5-point scales. The first version comprising 118 items was shortened to 63 items after conducting interviews using concurrent think aloud. A further 3 items giving no information were removed after piloting the questionnaire on 179 students. The 27 items of part A were structured in 7 factors (PCA): image, personal ambition, patient orientation, work-life balance, future perspectives, job-related ambition, and variety in job. This structure had a critical fit in the CFA applied to the final version filled out by 1 299 students. Internal consistency of the factors was satisfactory to very good (Cronbach's α=0.55-0.81).

CONCLUSION

The questionnaire showed good psychometric properties. Further, not assessed factors influence career choice resulting in unexplained variance in our dataset and the critical fit of the model.

[Aspirations of medical students: "planning for a secure career" - results of an online-survey among students at five medical schools in Germany]

BACKGROUND

In times of shortage of doctors, expectations and interests of the future generation of doctors towards their career aspiration is of major importance. The aim of this study was to analyze expectations of medical students at the five medical schools in the State of Baden-Wuerttemberg (Germany) concerning their career choice and factors influencing it.

METHODS

Between January and February 2010, 1299 medical students (out of 12 062 medical students at the five medical schools) participated in an online-survey. In addition to sociodemographic items, career choice and aspects of planning reliability were raised.

RESULTS

Three quarters of the students assign a medical profession for their future occupation. There is a dominance of internal medicine (n = 152), gynaecology (n = 127), paediatrics (n = 125), surgery (n = 115), anaesthesiology (n = 101), and family medicine (n = 88). The time point of decision varies between the different undergraduate years of medical school and specialty. Students at the beginning of their studies seem to be interested mostly in surgery. During medical school the interests towards internal medicine grows. Regarding planning dependability important aspects for medical students were to work in a job that has a future (61.2 % fully agree), to have a safe job (57.7 %), and to have a safe income (57.1 %). Less important seems to be to have good opportunity to earn money (29.6 %).

CONCLUSIONS

Interest in a certain specialty changes markedly at during medical school. Factors such as economical guarantee, good future prospects and also the studies itself have an essential impact for students on choosing a specific career. Strategies to face physicians' shortage in different specialties need to be close to the needs and expectations of future physicians. This is not only valid for the undergraduate time period but also for the work circumstances of their future.

Antifungal therapy with itraconazole impairs the anti-lymphoma effects of rituximab by inhibiting recruitment of CD20 to cell surface lipid rafts

Immunotherapy with rituximab alone or in conjunction with chemotherapy has significantly improved the treatment outcome of B-cell lymphoma patients. Nevertheless, a subpopulation of patients does not respond to rituximab. The reason for treatment failure as well as the exact mechanism of action is still uncertain. The function of rituximab has long been associated with the partitioning of CD20 molecules to membrane microdomains. Here, we show that concomitant antifungal treatment with itraconazole impairs the rituximab anti-lymphoma effect both in vitro and in vivo. At the molecular level, recruitment of CD20 to lipid rafts is inhibited in the presence of itraconazole. Furthermore, calcium influx, which is crucial for rituximab-mediated cell death, was nearly completely abolished by itraconazole treatment. In contrast, the antifungal drug caspofungin did not inhibit CD20 recruitment to lipid rafts, nor did it affect calcium influx or the cytotoxic effect of rituximab. The finding that itraconazole also abolished the cytotoxic effects of other therapeutic antibodies directed against lipid raft-associated molecules (i.e., CD20 and CD52) but not those against the non-raft-associated molecule CD33 further supported our proposed mechanism of action. Our results argue that concomitant medications must be adjusted carefully to achieve optimal antitumor effects with monoclonal antibodies.

[Information on medications - How do chronically ill patients assess counselling on drugs in general practice?]

BACKGROUND AND OBJECTIVE

Patients with chronic disease have to rely on safe and efficacious drug treatment. They therefore need individual information on their medicaton, in which counselling within the setting of general practice plays a pivotal role. However, information that seems to be relevant from the doctor's point of view is not necessarily consistent with the information patients consider to be necessary. The question was addressed in this study on to what extent patients are satisfied with the information they have received on their medication in general practice?

METHODS

A standardized questionnaire consisting of the SIMS-D (German version of the Satisfaction with Information about Medicines Scale) and MARS-D (German version of the Medication Adherence Report Scale) was sent to 834 chronically ill patients between March 2007 and April 2008.

RESULTS

Patients felt quite satisfied with the information they received on "action and usage" of medication (mean 6.95; range 0 - 9). They were not quite so satisfied with the information they received on "potential problems of medication". Self-reported adherence showed a high mean of 23.6 (range 5 - 25). Less than half of the doctors (43.6 %) inquired "always" or "often" whether patients were taking any other drugs than those prescribed.

CONCLUSION

Patients wish to have more information on potential drug-related problems. More attention needs to be given to a structured review of drugs prescribed in general practice.

Mechanisms regulating cytochrome c release in pancreatic mitochondria

BACKGROUND

Mechanisms of acinar cell death in pancreatitis are poorly understood. Cytochrome c release is a central event in apoptosis in pancreatitis. Here, we assessed the regulation of pancreatic cytochrome c release by Ca(2+), mitochondrial membrane potential (Delta Psi m), and reactive oxygen species (ROS), the signals involved in acute pancreatitis. We used both isolated rat pancreatic mitochondria and intact acinar cells hyperstimulated with cholecystokinin-8 (CCK-8; in vitro model of acute pancreatitis).

RESULTS

Micromolar amounts of Ca(2+) depolarised isolated pancreatic mitochondria through a mechanism different from the "classical" (ie, liver) mitochondrial permeability transition pore (mPTP). In contrast with liver, Ca(2+)-induced mPTP opening caused a dramatic decrease in ROS and was not associated with pancreatic mitochondria swelling. Importantly, we found that Ca(2+)-induced depolarisation inhibited cytochrome c release from pancreatic mitochondria, due to blockade of ROS production. As a result, Ca(2+) exerted two opposite effects on cytochrome c release: Ca(2+) per se stimulated the release, whereas Ca(2+)-induced depolarisation inhibited it. This dual effect caused a non-monotonous dose-dependence of cytochrome c release on Ca(2+). In intact acinar cells, cytochrome c release, caspase activation and apoptosis were all stimulated by ROS and Ca(2+), and inhibited by depolarisation, corroborating the findings on isolated pancreatic mitochondria.

CONCLUSIONS

These data implicate ROS as a key mediator of CCK-induced apoptotic responses. The results indicate a major role for mitochondria in the effects of Ca(2+ )and ROS on acinar cell death. They suggest that the extent of apoptosis in pancreatitis is regulated by the interplay between ROS, Delta Psi m and Ca(2+). Stabilising mitochondria against loss of Delta Psi m may represent a strategy to mitigate the severity of pancreatitis.

Differential expression of genes encoding tight junction proteins in colorectal cancer: frequent dysregulation of claudin-1, -8 and -12

BACKGROUND AND AIMS

As integral membrane proteins, claudins form tight junctions together with occludin. Several claudins were shown to be up-regulated in various cancer types. We performed an expression analysis of genes encoding tight junction proteins to display differential gene expression on RNA and protein level and to identify and validate potential targets for colorectal cancer (CRC) therapy.

PATIENTS AND METHODS

Amplified and biotinylated cRNA from 30 microdissected CRC specimen and corresponding normal tissues was hybridized to Affymetrix U133set GeneChips. Quantification of differential protein expression of claudin-1, -8 and -12 between normal and corresponding tumour tissues was performed by Western blot analyses. Paraffin-embedded CRC tissue samples, colon cancer cell lines and normal tissue microarray were analysed for protein expression of claudin-1 by immunohistochemistry (IHC).

RESULTS

Claudin-1 (CLDN1) and -12 (CLDN12) are frequently overexpressed in CRC, whereas claudin-8 (CLDN8) shows down-regulation in tumour tissue on RNA level. Quantification of proteins confirmed the overexpression of claudin-1 in tumour tissues, whereas changes of claudin-8 and -12 were not significantly detectable on protein level. IHC confirmed the markedly elevated expression level of claudin-1 in the majority of CRC, showing membranous and intracellular vesicular staining.

CONCLUSIONS

Differential expression of genes encoding claudins in CRC suggests that these tight junction proteins may be associated to and involved in tumorigenesis. CLDN1 is frequently up-regulated in large proportion of CRC and may represent potential target molecule for blocking studies in CRC.