A biomechanical mathematical model for the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds

A continuum hypothesis-based, biomechanical model is presented for the simulation of the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds that cover a large surface area. Since wound contraction mainly takes place in the dermal layer of the skin, solely a portion of this layer is included explicitly into the model. This portion of dermal layer is modeled as a heterogeneous, orthotropic continuous solid with bulk mechanical properties that are locally dependent on both the local concentration and the local geometrical arrangement of the collagen bundles. With respect to the dynamic regulation of the geometrical arrangement of the collagen bundles, it is assumed that a portion of the collagen molecules are deposited and reoriented in the direction of movement of (myo)fibroblasts. The remainder of the newly secreted collagen molecules are deposited by ratio in the direction of the present collagen bundles. Simulation results show that the distribution of the collagen bundles influences the evolution over time of both the shape of the wounded area and the degree of overall contraction of the wounded area. Interestingly, these effects are solely a consequence of alterations in the initial overall distribution of the collagen bundles, and not a consequence of alterations in the evolution over time of the different cell densities and concentrations of the modeled constituents. In accordance with experimental observations, simulation results show furthermore that ultimately the majority of the collagen molecules ends up permanently oriented toward the center of the wound and in the plane that runs parallel to the surface of the skin.

     

Determination of opipramol in human plasma by high-performance liquid chromatography with photometric detection using a cyanopropyl column

A high-performance liquid chromatographic method is described for the determination of opipramol in human plasma. Opipramol was extracted into tert.-butylmethyl ether, separated on a cyanopropyl silica column and detected at 254 nm. Imipramine was used as internal standard. The limit of quantitation was 250 pg/ml using 1.5 ml plasma. Precision was better than 9%, inaccuracy less than 8%. The assay is more sensitive than previously published methods, and it has been applied to the analysis of plasma samples from a pharmacokinetic study.     

Values Determine the (In)Effectiveness of Informational Interventions in Promoting Pro-Environmental Behavior

Informational interventions (e.g., awareness campaigns, carbon footprint calculators) are built on the assumption that informing the public about the environmental consequences of their actions should result in increased pro-environmental intentions and behavior. However, empirical support for this reasoning is mixed. In this paper, we argue that informational interventions may succeed in improving people’s knowledge about the negative environmental consequences of one’s actions, but this knowledge will not gain motivational force if people do not consider protecting the environment an important personal value. In an experiment, we measured individual differences in value priorities, and either presented participants a movie clip that portrayed the negative environmental consequences of using bottled water, or a control movie. As predicted, we found that the environmental movie improved recipients’ knowledge of the negative environmental impact of bottled water, but this knowledge only resulted in concomitant changes in intentions and acceptability of related policies among participants who strongly endorsed biospheric (i.e. environmental) values, while having no effect on those who care less about the environment. Interestingly, the results suggest that although informational interventions are perhaps not always successful in directly affecting less environmentally-conscious recipients, they could still have beneficial effects, because they make those who strongly care about the environment more inclined to act on their values.     

Evoked Emotions Predict Food Choice

In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments. Therefore, the focus within recent studies shifted towards using emotion-profiling methods that successfully can discriminate between products that are equally liked. However, it is unclear how well scores from emotion-profiling methods predict actual food choice and/or consumption. To test this, we proposed to decompose emotion scores into valence and arousal scores using Principal Component Analysis (PCA) and apply Multinomial Logit Models (MLM) to estimate food choice using liking, valence, and arousal as possible predictors. For this analysis, we used an existing data set comprised of liking and food-evoked emotions scores from 123 participants, who rated 7 unlabeled breakfast drinks. Liking scores were measured using a 100-mm visual analogue scale, while food-evoked emotions were measured using 2 existing emotion-profiling methods: a verbal and a non-verbal method (EsSense Profile and PrEmo, respectively). After 7 days, participants were asked to choose 1 breakfast drink from the experiment to consume during breakfast in a simulated restaurant environment. Cross validation showed that we were able to correctly predict individualized food choice (1 out of 7 products) for over 50% of the participants. This number increased to nearly 80% when looking at the top 2 candidates. Model comparisons showed that evoked emotions better predict food choice than perceived liking alone. However, the strongest predictive strength was achieved by the combination of evoked emotions and liking. Furthermore we showed that non-verbal food-evoked emotion scores more accurately predict food choice than verbal food-evoked emotions scores.     

Book Review: C. Perrot-Rechenmann and G. Hagen (eds.): Auxin Molecular Biology

Plant Cell, Tissue and Organ Culture (PCTOC) -     

Fungal biosynthesis of non-ribosomal peptide antibiotics and alpha, alpha-dialkylated amino acid constituents.

Zervamicins (Zrv) IIA and IIB are membrane modifying peptide antibiotics of fungal origin, characterized by a sequence of 15 amino acid residues. The primary structure of Zrv-IIA contains five alpha-aminoisobutyric acid residues at positions 4, 7, 9, 12 and 14 of the linear peptide. The sequence of Zrv-IIB is similar, but contains a D-isovaline at position 4. When the free amino acid Aib was added to the peptone-glucose culture medium, the fungus Emericellopsis salmosynnemata produced Zrv-IIA as the major secondary metabolite, whereas addition of DL-Iva to the culture led to a high production of Zrv-IIB. This observation is rationalized by a lack of selectivity of the non-ribosomal peptide synthetase with respect to the thiolester activated amino acid substrates during step 12 of peptide synthesis. Analysis of the configuration of the Iva residue of Zrv-IIB showed a high enantiomeric purity of the D-enantiomer, indicating a high stereoselectivity of the peptide synthetase for this substrate.When the culture was supplemented with [(15)N]DL-Iva, the nitrogen isotope was not only found at the D-Iva residue, but surprisingly also at the Aib residues as well as at the proteinogenic residues of Zrv. The partial catabolism of exogenous [(15)N]DL-Iva is explained by the assumption of a decarboxylation-dependent transamination reaction, catalysed by 2,2-dimethylglycine decarboxylase. The same enzyme might also be involved in the reversed carboxylation reactions of acetone and 2-butanone, during the anabolic biosynthesis of Aib and Iva, respectively. Zrv might possibly act as a thermodynamic sink to shift these equilibrium reactions towards the reversed side.     

Novel Surface Display System for Proteins on Non-Genetically Modified Gram-Positive Bacteria

A novel display system is described that allows highly efficient immobilization of heterologous proteins on bacterial surfaces in applications for which the use of genetically modified bacteria is less desirable. This system is based on nonliving and non-genetically modified gram-positive bacterial cells, designated gram-positive enhancer matrix (GEM) particles, which are used as substrates to bind externally added heterologous proteins by means of a high-affinity binding domain. This binding domain, the protein anchor (PA), was derived from the Lactococcus lactis peptidoglycan hydrolase AcmA. GEM particles were typically prepared from the innocuous bacterium L. lactis, and various parameters for the optimal preparation of GEM particles and binding of PA fusion proteins were determined. The versatility and flexibility of the display and delivery technology were demonstrated by investigating enzyme immobilization and nasal vaccine applications.     

Temporal and spatial variation in the occurrence of Palearctic warblers around Lake Victoria

Goudswaard, K. & Wanink, J.H. 2000. Temporal and spatial variation in the occurrence of Palearctic warblers around Lake Victoria. Ostrich 71 (1 & 2): 210–212.

Only one Palearctic warbler species, the Sedge Warbler, wintered at the south-eastem shores of Lake Victoria. Willow Warbler and Garden Warbler occurred mainly on passage, with peak values in the first lunar quarter, the period in which lakeflies would normally swarm. Higher warbler densities have been reported from the north-western shores. This agrees with our idea that the prevailing eastern winds will result in a higher availability of lakeflies to warblers at the western side of the lake.