Metabolic, endocrine, haemodynamic and pulmonary responses to different types of exercise in individuals with normal or reduced liver function

The liver is central to the metabolic response to exercise but measurements of effects of reduced liver function on the physiological adaptation to exercise are scarce. We investigated metabolic, endocrine, pulmonary and haemodynamic responses to exercise in 15 healthy untrained controls (Co) and in 30 subjects with reduced liver function (i.e. liver cirrhosis, Ci). The following protocols were used: protocol 1 maximal oxygen uptake and anaerobic threshold (AT), protocol 2 stepwise increases in exercise intensity from 0 to 40% giving steady-stage conditions, protocol 3 1 h exercise at 20% . Muscle glycogen content was determined in 15 Ci. Spirometry was essentially normal in Ci. Result: protocol 1 Ci had impaired and reduced AT (P < 0.05). Basal plasma concentrations of insulin, glucagon, growth hormone and adrenaline were increased in Ci (P < 0.05); cortisol was normal. During exercise, only glucagon remained different between groups. In protocol 2 Ci had decreased resting respiratory exchange ratio (RQ: p < 0.05) associated with increased plasma concentrations of free fatty acids and glycerol. They had disproportionately enhanced lipolysis and RQ. heart rate (+ 24%), ventilation (+ 28%), thermal effects of exercise (+ 31%) and intrapulmonary shunt volume (+ 76%), which accounted for 11.7 (SD 3.0) or 7.4 (SD 0.9%) of cardiac output during exercise in Ci and Co, respectively (P < 0.05 for all the differences reported). The metabolic effects of Ci were independent of the clinical and nutritional state of the patients. In protocol 3 muscle glycogen content was highly variable in Ci, but mean values were normal [16.9 (SD 8.9) mol·g^–1 wet mass]. Glycogen content positively correlated with resting and exercise-induced RQ, but negatively correlated with the exercise-induced alterations in plasma glucose concentration. From these results we concluded that with reduced liver function , and AT are reduced, but metabolic, pulmonary and haemodynamic reponses per unit power output are enhanced. Muscle glycogen content would seem to contribute to the metabolic response, but its mobilization to be limited in individuals with reduced liver function.Dedicated to Professor D.F.W. Schmidt on the occasion of his 70th birthday     

A meta‐analysis on growth,physiological, and biochemical responses of woody species to ground‐level ozone highlights the role of plant functional types

The carbon‐sink strength of temperate and boreal forests at midlatitudes of the northern hemisphere is decreased by ozone pollution, but knowledge on subtropical evergreen broadleaved forests is missing. Taking the dataset from Chinese studies covering temperate and subtropical regions, effects of elevated ozone concentration ([O₃]) on growth, biomass, and functional leaf traits of different types of woody plants were quantitatively evaluated by meta‐analysis. Elevated mean [O₃] of 116 ppb reduced total biomass of woody plants by 14% compared with control (mean [O₃] of 21 ppb). Temperate species from China were more sensitive to O₃ than those from Europe and North America in terms of photosynthesis and transpiration. Significant reductions in chlorophyll content, chlorophyll fluorescence parameters, and ascorbate peroxidase induced significant injury to photosynthesis and growth (height and diameter). Importantly, subtropical species were significantly less sensitive to O₃ than temperate ones, whereas deciduous broadleaf species were significantly more sensitive than evergreen broadleaf and needle‐leaf species. These findings suggest that carbon‐sink strength of Chinese forests is reduced by present and future [O₃] relative to control (20–40 ppb). Given that (sub)‐tropical evergreen broadleaved species dominate in Chinese forests, estimation of the global carbon‐sink constraints due to [O₃] should be re‐evaluated.     

Evolutionary responses of Drosophila melanogaster to selection at different larval densities: changes in genetic variation,specialization and phenotypic plasticity

Abstract We studied the evolutionary response to novel environments by applying artificial selection for total progeny biomass in populations of Drosophila melanogaster maintained at three different larval population densities. We found the relative amount of genetic variability for characters related with biomass to be lower and the correlation between them more negative at the intermediate density, and that selection resulted in changes in phenotypic plasticity and in patterns of resource allocation between traits. We found some evidence for tradeoffs between densities, which suggests that populations living at heterogeneous densities might be subject to disruptive selection. Our results show that adaptation to new environments may be a complex process, involving not only changes in trait means, but also in correlations between traits and between environments.     

Dynamic dentin: A quantitative microscopic assessment of age and spatial changes to matrix architecture,peritubular dentin,and collagens types I and III

To investigate age and site-related changes to human dentin collagen, sound human teeth collected from donors aged 13–29 (young) and 50–74 (aged) years (n = 9/group) were cut to shallow and deep sites. Dentin collagen orientation and fibril bundling was investigated using the Picrosirius Red (PSR) stain observed under cross-polarized light microscopy (Pol), and collagen distribution was investigated using Confocal Laser Scanning Microscopy (CLSM). Collagen types III to I distribution in peritubular dentin (PTD) was revealed using Herovici stain and brightfield microscopy. Image analysis software and linear mixed modelling quantified outcomes. In situ dentin collagen was observed using Xenon Plasma Focussed Ion Beam Scanning Electron Microscopy (Xe PFIB-SEM). The PSR-Pol analysis revealed less coherently aligned and more bundled collagen fibrils in aged dentin (P = 0.005). Deep inner dentin collagen in both groups were less coherently aligned with reduced bundling. Regardless of age, CLSM showed collagen distribution remained stable; and more collagen type III was detectable in PTD located in inner dentin (Young: P = 0.006; Aged: P = 0.008). Observations following Xe PFIB-SEM cross-sectioning showed apatite-like deposits surrounding large intratubular collagen fibers, and evidence of smaller intertubular dentin collagen fibrils in situ. In conclusion, aging changes collagen network architecture, but not distribution or content.