Monitoring muscle oxygenation and myoelectric activity after damage-inducing exercise

In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage

De vruchtbaarheidscyclus na afkalven

Om na te gaan hoe het tijdstip van de eerste ovulatie na afkalven verloopt bij hoogproduktieve koeien is op twee bedrijven van de Waiboerhoeve gedurende een jaar van alle afkalvende koeien het progesterongehalte in de melk onderzocht tot 50 dagen na afkalven

Disruption of Cxcr3 chemotactic signaling alters lysosomal function and renders macrophages more microbicidal

Chemotaxis and lysosomal function are closely intertwined processes essential for the inflammatory response and clearance of intracellular bacteria. We used the zebrafish model to examine the link between chemotactic signaling and lysosome physiology in macrophages during mycobacterial infection and wound-induced inflammation in vivo. Macrophages from zebrafish larvae carrying a mutation in a chemokine receptor of the Cxcr3 family display upregulated expression of vesicle trafficking and lysosomal genes and possess enlarged lysosomes that enhance intracellular bacterial clearance. This increased microbicidal capacity is phenocopied by inhibiting the lysosomal transcription factor EC, while its overexpression counteracts the protective effect of chemokine receptor mutation. Tracking macrophage migration in zebrafish revealed that lysosomes of chemokine receptor mutants accumulate in the front half of cells, preventing macrophage polarization during chemotaxis and reaching sites of inflammation. Our work shows that chemotactic signaling affects the bactericidal properties and localization during chemotaxis, key aspects of the inflammatory response

The diverse nature of island isolation and its effect on land bridge insular faunas

Aim: Isolation is a key factor in island biology. It is usually defined as the distance to the geographically nearest mainland, but many other definitions exist. We explored how testing different isolation indices affects the inference of impacts of isolation on faunal characteristics. We focused on land bridge islands and compared the relationships of many spatial and temporal (i.e., through time) isolation indices with community‐, population‐ and individual‐level characteristics (species richness, population density and body size, respectively). Location: Aegean Sea islands, Greece. Time period: Current. Taxon: Many animal taxa. Methods: We estimated 21 isolation indices for 205 islands and recorded species richness data for 15 taxa (invertebrates and vertebrates). We obtained body size data for seven lizard species and population density data for three. We explored how well indices predict each characteristic, in each taxon, by conducting a series of ordinary least squares regressions (controlling for island area when needed) and a meta‐analysis. Results: Isolation was significantly (and negatively) associated with species richness in 10 of 15 taxa. It was significantly (and positively) associated with body size in only one of seven species and was not associated with population density. The effect of isolation on species richness was much weaker than that of island area, regardless of the index tested. Spatial indices generally out‐performed temporal indices, and indices directly related to the mainland out‐performed those related mainly to neighbouring islands. No index was universally superior to others, including the distance to the geographically nearest mainland. Main conclusions: The choice of index can alter our perception of the impacts of isolation on biological patterns. The nearly automatic, ubiquitous use of distance to the geographically nearest mainland misrepresents the complexity of the effects of isolation. We recommend the simultaneous testing of several indices that represent different aspects of isolation, in order to produce more constructive and thorough investigations and avoid imprecise inference