Obesity and impairment in psychosocial functioning in women: the mediating role of eating disorder features

Objective: The objective was to test the hypothesis that, in women, the association between obesity and impairment in psychosocial functioning is mediated by levels of weight and shape concerns and/or binge‐eating frequency. Research Methods and Procedures: Self‐report measures of eating disorder psychopathology, mental health functioning, subjective quality of life in the psychological and social domains, and days “out‐of‐role” associated with any (physical or mental) health problem, were completed by a community sample of women classified as obese (BMI ≥30 kg/m², n = 639) or non‐obese (BMI <30 kg/m², n = 4253). For each of the dependent measures, regression models were used to test the hypothesis of mediation by comparing the strength of the relationship between independent and dependent variables with and without inclusion of the putative mediator in the regression model. Results: On each measure, the conditions for perfect mediation were satisfied when weight or shape concerns acted as the putative mediator, indicating that there was no association between obesity and functional impairment after controlling for weight or shape concerns. In contrast, associations between obesity and impairment in psychosocial functioning remained highly significant when binge‐eating frequency was the putative mediator. Discussion: The findings suggest that in women, weight and shape concerns are an important mediator of the relationship between obesity and impairment in psychosocial functioning, whereas binge eating may not be of primary importance. A greater focus on body acceptance in obesity treatment may be indicated.     

Nanoparticle-enzyme hybrid systems for nanobiotechnology

Biomolecule-nanoparticle (NP) [or quantum-dot (QD)] hybrid systems combine the recognition and biocatalytic properties of biomolecules with the unique electronic, optical, and catalytic features of NPs and yield composite materials with new functionalities. The biomolecule-NP hybrid systems allow the development of new biosensors, the synthesis of metallic nanowires, and the fabrication of nanostructured patterns of metallic or magnetic NPs on surfaces. These advances in nanobiotechnology are exemplified by the development of amperometric glucose sensors by the electrical contacting of redox enzymes by means of AuNPs, and the design of an optical glucose sensor by the biocatalytic growth of AuNPs. The biocatalytic growth of metallic NPs is used to fabricate Au and Ag nanowires on surfaces. The fluorescence properties of semiconductor QDs are used to develop competitive maltose biosensors and to probe the biocatalytic functions of proteases. Similarly, semiconductor NPs, associated with electrodes, are used to photoactivate bioelectrocatalytic cascades while generating photocurrents.     

Characterization of the bga1-encoded glycoside hydrolase family 35 beta-galactosidase of Hypocrea jecorina with galacto-beta-D-galactanase activity

The extracellular bga1-encoded beta-galactosidase of Hypocrea jecorina (Trichoderma reesei) was overexpressed under the pyruvat kinase (pki1) promoter region and purified to apparent homogeneity. The monomeric enzyme is a glycoprotein with a molecular mass of 118.8 +/- 0.5 kDa (MALDI-MS) and an isoelectric point of 6.6. Bga1 is active with several disaccharides, e.g. lactose, lactulose and galactobiose, as well as with aryl- and alkyl-beta-D-galactosides. Based on the catalytic efficiencies, lactitol and lactobionic acid are the poorest substrates and o-nitrophenyl-beta-D-galactoside and lactulose are the best. The pH optimum for the hydrolysis of galactosides is approximately 5.0, and the optimum temperature was found to be 60 degrees C. Bga1 is also capable of releasing D-galactose from beta-galactans and is thus actually a galacto-beta-D-galactanase. beta-Galactosidase is inhibited by its reaction product D-galactose and the enzyme also shows a significant transferase activity which results in the formation of galacto-oligosaccharides.     

Standardisation of rapid in-gel digestion by mass spectrometry

In-gel digestion has been standardised using a poly(propylene) disposable. We designed a four-step rapid and simple in-gel digestion protocol which is carried out in one self-contained reaction tube avoiding keratin contamination. In order to quantify the efficiency of in-gel digestion, we developed a rapid on-column peptide acetylation protocol. Results show that trypsin in-gel uptake is increased and in-gel digestion is 90% complete within 15 min. We further show that spectrum quality, peptide yield and sequence coverage for mass spectrometric analysis are enhanced. We utilise 2-D PAGE separation of photosystem II from barley to demonstrate that the protocol facilitates identification of highly hydrophobic membrane proteins.     

Minireview: Recent progress in hemocyanin research

This review summarizes recent highlights of our joint work on the structure, evolution, and function of a family of highly complex proteins, the hemocyanins. They are blue-pigmented oxygen carriers, occurring freely dissolved in the hemolymph of many arthropods and molluscs. They are copper type-3 proteins and bind one dioxygen molecule between two copper atoms in a side-on coordination. They possess between 6 and 160 oxygen-binding sites, and some of them display the highest molecular cooperativity observed in nature. The functional properties of hemocyanins can be convincingly described by either the Monod-Wyman-Changeux (MWC) model or its hierarchical extension, the Nested MWC model; the latter takes into account the structural hierarchies in the oligomeric architecture. Recently, we applied these models to interpret the influence of allosteric effectors in detailed terms. Effectors shift the allosteric equilibria but have no influence on the oxygen affinities characterizing the various conformational states. We have shown that hemocyanins from species living at different environmental temperatures have a cooperativity optimum at the typical temperature of their natural habitat. Besides being oxygen carriers, some hemocyanins function as a phenoloxidase (tyrosinase/catecholoxidase) which, however, requires activation. Chelicerates such as spiders and scorpions lack a specific phenoloxidase, and in these animals activated hemocyanin might catalyse melanin synthesis in vivo. We propose a similar activation mechanism for arthropod hemocyanins, molluscan hemocyanins and tyrosinases: amino acid(s) that sterically block the access of phenolic compounds to the active site have to be removed. The catalysis mechanism itself can now be explained on the basis of the recently published crystal structure of a tyrosinase. In a series of recent publications, we presented the complete gene and primary structure of various hemocyanins from different molluscan classes. From these data, we deduced that the molluscan hemocyanin molecule evolved ca. 740 million years ago, prior to the separation of the extant molluscan classes. Our recent advances in the 3D cryo-electron microscopy of hemocyanins also allow considerable insight into the oligomeric architecture of these proteins of high molecular mass. In the case of molluscan hemocyanin, the structure of the wall and collar of the basic decamers is now rapidly becoming known in greater detail. In the case of arthropod hemocyanin, a 10-? structure and molecular model of the Limulus 8 × 6mer shows the amino acids at the various interfaces between the eight hexamers, and reveals histidine-rich residue clusters that might be involved in transferring the conformational signals establishing cooperative oxygen binding.     

Inhibition of TGF-beta2 with AP 12009 in recurrent malignant gliomas: from preclinical to phase I/II studies

Transforming growth factor-beta2 (TGF-beta2) is known to suppress the immune response to cancer cells and plays a pivotal role in tumor progression by regulating key mechanisms including proliferation, metastasis, and angiogenesis. For targeted protein suppression the TGF-beta2-specific antisense oligodeoxynucleotide AP 12009 was developed. In vitro experiments have been performed to prove specificity and efficacy of the TGF-beta2 inhibitor AP 12009 employing patient-derived malignant glioma cells as well as peripheral blood mononuclear cells (PBMCs) from patients. Clinically, the antisense compound AP 12009 was assessed in three Phase I/II-studies for the treatment of patients with recurrent or refractory malignant (high-grade) glioma WHO grade III or IV. Although the study was not primarily designed as an efficacy evaluation, prolonged survival compared to literature data and response data were observed, which are very rarely seen in this tumor indication. Two patients experienced long-lasting complete tumor remissions. These results implicate targeted TGF-beta2-suppression using AP 12009 as a promising novel approach for malignant gliomas and other highly aggressive, TGF-beta-2-overexpressing tumors.     

Metabolic reconstruction and modeling of nitrogen fixation in Rhizobium etli

Rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. This symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. Rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. A genome-scale approach, integrating the biochemical information available for R. etli, constitutes an important step toward understanding the symbiotic relationship and its possible improvement. In this work we present a genome-scale metabolic reconstruction (iOR363) for R. etli CFN42, which includes 387 metabolic and transport reactions across 26 metabolic pathways. This model was used to analyze the physiological capabilities of R. etli during stages of nitrogen fixation. To study the physiological capacities in silico, an objective function was formulated to simulate symbiotic nitrogen fixation. Flux balance analysis (FBA) was performed, and the predicted active metabolic pathways agreed qualitatively with experimental observations. In addition, predictions for the effects of gene deletions during nitrogen fixation in Rhizobia in silico also agreed with reported experimental data. Overall, we present some evidence supporting that FBA of the reconstructed metabolic network for R. etli provides results that are in agreement with physiological observations. Thus, as for other organisms, the reconstructed genome-scale metabolic network provides an important framework which allows us to compare model predictions with experimental measurements and eventually generate hypotheses on ways to improve nitrogen fixation.     

Strong seasonal differences of bacterial polysaccharide utilization in the North Sea over an annual cycle

Marine heterotrophic bacteria contribute considerably to global carbon cycling, in part by utilizing phytoplankton-derived polysaccharides. The patterns and rates of two different polysaccharide utilization modes – extracellular hydrolysis and selfish uptake – have previously been found to change during spring phytoplankton bloom events. Here we investigated seasonal changes in bacterial utilization of three polysaccharides, laminarin, xylan and chondroitin sulfate. Strong seasonal differences were apparent in mode and speed of polysaccharide utilization, as well as in bacterial community compositions. Compared to the winter month of February, during the spring bloom in May, polysaccharide utilization was detected earlier in the incubations and a higher portion of all bacteria took up laminarin selfishly. Highest polysaccharide utilization was measured in June and September, mediated by bacterial communities that were significantly different from spring assemblages. Extensive selfish laminarin uptake, for example, was detectible within a few hours in June, while extracellular hydrolysis of chondroitin was dominant in September. In addition to the well-known Bacteroidota and Gammaproteobacteria clades, the numerically minor verrucomicrobial clade Pedosphaeraceae could be identified as a rapid laminarin utilizer. In summary, polysaccharide utilization proved highly variable over the seasons, both in mode and speed, and also by the bacterial clades involved.