Limb kinematics, kinetics and muscle dynamics during the sit-to-stand transition in greyhounds

Standing up from a prone position is a critical daily activity for animals: failing to do so effectively may cause an injurious fall or increase predation susceptibility. This sit-to-stand behaviour (StS) is biomechanically interesting because it necessitates transitioning through near-maximal joint motion ranges from a crouched (i.e., poor mechanical advantage) to a more upright posture. Such large joint excursions should require large length changes of muscle-tendon units. Here we integrate experimental and musculoskeletal simulation methods to quantify the joint motions, limb forces, and muscle fibre forces, activations and length changes during StS in an extreme athlete – the greyhound – which has large hindlimb muscles bearing short-fibred distal muscles and long tendons. Study results indicate that hindlimb anti-gravity muscle fibres operate near their ~50% limits of length change during StS; mostly by starting at highly lengthened positions. StS also requires high muscle activations (>50%), in part due to non-sagittal motions. Finally, StS movements require passive non-muscular support in the distal hindlimb where short-fibred muscles are incapable of sustaining StS themselves. Non-locomotor behaviours like StS likely impose important trade-offs between muscle fibre force capacity and length changes, as well as active and passive mechanisms of support, that have been neglected in locomotor biomechanics studies

Analysis of two methods of isometric muscle contractions during the anti-G straining maneuver

This study investigated the difference in Mean Arterial Pressure (MAP) and Cardiac Output (CO) between two methods of isometric muscle contractions during the Anti-G Straining Maneuver (AGSM). 12 subjects (ages 18 to 38 yrs, height 176.8 +/- 7.4 cm, body mass 78.8 +/- 15.6 kg, percent body fat 14.3 +/- 6.6%) participated in the study. The study was a one-way within-subject design with test conditions counterbalanced. Two methods of isometric muscle contractions lasting 30 seconds each were assessed; an isometric push contraction and an isometric muscle tensing contraction. The dependent parameters were MAP and CO. The average MAP during the push contraction was 123 mmHg, SD +/- 11 and for tense was 118 mmHg, SD +/- 8. CO was 7.6 L/min, SD +/- 1.6 for push and 7.9 L/min, SD +/- 2.0 for tense method. Dependent t-tests revealed t(11) = 1.517, p = 0.157 for MAP and t(11) = 0.875, p = 0.400 for CO. This study demonstrated that the two methods of isometric muscle contractions were not statistically different with regards to MAP and CO. Therefore, both forms of isometric contractions may be potentially useful when performing the muscle contraction portion of the AGSM

Optimization and validation of an analytical method to measure phenolic acids

A method has been developed to separate and quantify phenolic acids (gallic-, caffeic-, p-coumaric-, o-coumaric and ferulic acid) and their microbial conversion products by means of high performance liquid chromatography (HPLC). The separation was performed using a Inertsil ODS-3, 3 µm (4.6 * 150 mm) column. Acetonitrile and 50 mM phosphoric acid formed the mobile phase. Quantification was done at three different wavelengths. The method has been validated by measuring the linearity, the limit of detection, the range, the limit of quantification and the reproducibility

Metabolism of ferulic acid by two lactic acid bacteria

Lactic acid fermentation of vegetable products, which are a rich source of phenolic acids, is a technique to prolong the shelf-life. It has been known that phenolic acids not only influence growth of Lactobacillus sp. but also that different Lactobacillus strains are able to metabolise the phenolic compounds. Ferulic acid (FA) is a major phenolic acid present in vegetable products and was chosen to use in the fermentation experiments. In this study, it was aimed to investigate the effect of different FA concentrations (0, 0.5, 1.5 and 3 mM) on the growth as well as to quantify the conversion products of FA of two lactobacillus strains. The two lactic acid bacteria were Lactobacillus plantarum (LMG6907) and Lactobacillus collinoides (LMG9194). The strains were grown until end-stationary phase in MRS medium at 30 °C. Inoculation was done at 1 %. Also samples were taken to identify and quantify FA and its conversion products. Quantification was done by LC-DAD, while identification was performed by UPLC-HDMS-Q-TOF. From the fermentation experiments, it was observed that none of the FA concentrations clearly affected the growth of both lactobacilli. However metabolism of FA by these bacteria was different, and was dependent on the added FA concentration. Lactobacillus plantarum converted FA into 4-vinylguaiacol and hydroferulic acid. These conversion products appeared in different stages of the growth phase, and were formed depending on the added FA concentration. Lactobacillus collinoides converted FA only into 4-vinylguaiacol, and to a much lesser extent than Lactobacillus plantarum. Also, a clear effect of the added FA concentration on the extent of conversion to 4-vinylguaiacol was observed for Lactobacillus collinoides fermentations. From the results it can be suggested that metabolic pathways on phenolic acids between the different lactic acid bacteria are different

Role of processing on bioaccessibility of minerals: influence of location of minerals and anti-nutritional factors in the plant

Phytate, phenolic compounds and fiber are known anti-nutritional factors (ANFs) that contribute to the low bioaccessibility and bioavailability of iron and zinc in plant foods. Better insight into the localization of minerals and anti-nutritional factors in plant tissues, as well as on the mechanisms of interaction between minerals and ANFs, may lead to better targeted processing for improvement of the bioaccessibility of minerals in plant foods. This review highlights the subcellular distribution of iron and zinc and their ANFs in plant organs, as well as the mechanisms of interaction between these metals and their ANFs. These insights are then used to better clarify the role of various processing technologies, like mechanical treatments, soaking, germination, fermentation and heating, on improving the bioaccessibility of iron and zinc in plant foods

Machining and Selective Laser Hardening of Complex Shaped Components on a Multi-axis Machining center

This paper presents the activities performed on a Mori Seiki NTX2000 mill-turn center, made available to the KU Leuven by the Machine Tools Technologies Research Foundation (MTTRF). Besides various educational activities, the equipment is used in research focusing on the machining of complex shaped parts, requiring selective hardened regions. This paper focusses on the development of a selective laser hardening set-up, including the optical and mechanical design, within a DMG MORI NTX2000 machining center. This development is also supported by thermal simulations of the selective hardening process. A proof of concept, based on C45 steel, is also presented.status: publishe

Potential of lactic acid fermentation to produce health beneficial compounds from vegetable waste

During the production of vegetables, a lot of waste is produced. This waste still contains a high amount of important health beneficial compounds, e.g. phenolic compounds. Phenolic compounds in cabbage leaves appear in their bound form, conjugated with mono- and polysaccharides and/or linked to one or more of the phenolic groups. Several techniques are studied to release the phenolic compounds from these leaves. One possible processing technique is the use of lactic acid fermentation to release phenolic compounds from cabbage leaves. Therefore, cabbage leaves were mixed with sterile water and transferred into jars. Three heat treatments i.e. pasteurization, sterilization and no heat treatment, were performed on the leaves, combined with three different starters i.e. Lactobacillus plantarum, Lactobacillus collinoides and natural fermentation. The jars were incubated for 13 days at 30 °C and sampled on a regular base to follow growth and phenolic profile. Independent of the performed heat treatment, the pH increased during natural fermentation. In the incubations with L. plantarum, the pH immediately decreased, independent of the heat treatment. In a later stage of the fermentation, an increase in pH was monitored. For the incubations with L. collinoides, independent of the thermal treatment, the decrease in pH was at a later moment in time. In the case were no heat treatment was subjected to the leaves, an increase of pH was seen after 50 hours of fermentation. In the two other heat treated samples, inoculated with L. collinoides, the pH remained more or less constant. LC-analysis after acid hydrolysis of the fermented leaves showed clearly the release of 3 compounds. One of these compounds is identified as kaempferol. The amount of kaempferol stayed constant during fermentation. The other two peaks needs to be identified further and were degraded by the present microflora