Effect of Feed Restriction on Performance and Postprandial Nutrient Metabolism in Pigs Co-Infected with Mycoplasma hyopneumoniae and Swine Influenza Virus

As nutritional status and inflammation are strongly connected, feeding and nutritional strategies could be effective to improve the ability of pigs to cope with disease. The aims of this study were to investigate the impact of a feed restriction on the ability of pigs to resist and be tolerant to a coinfection with Mycoplasma hyopneumoniae (Mhp) and the European H1N1 swine influenza virus, and the consequences for nutrient metabolism, with a focus on amino acids. Two groups of specific pathogen-free pigs were inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum, the other group was subjected to a two-week 40% feed restriction starting one week before H1N1 infection. The two respective mock control groups were included. Three days post-H1N1 infection, 200 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over 4 hours to measure plasma nutrient concentrations. Throughout the study, clinical signs were observed and pathogens were detected in nasal swabs and lung tissues. Feed-restricted pigs presented shorter hyperthermia and a positive mean weight gain over the 3 days post-H1N1 infection whereas animals fed ad libitum lost weight. Both infection and feed restriction reduced postprandial glucose concentrations, indicating changes in glucose metabolism. Post-prandial plasma concentrations of the essential amino acids histidine, arginine and threonine were lower in co-infected pigs suggesting a greater use of those amino acids for metabolic purposes associated with the immune response. Altogether, these results indicate that modifying feeding practices could help to prepare animals to overcome an influenza infection. Connections with metabolism changes are discussed.     

L-proline uptake in human fibroblasts: evidence for a high-affinity system in addition to system A

Proline uptake was studied in human skin fibroblasts by simultaneous running of kinetic and inhibition experiments on the same cell lines. Two systems for proline uptake were shown: a high-affinity system not inhibited by alpha-(methylamino)isobutyric acid and a low affinity system inhibited by this amino acid (i.e. system A). These results appear to be of interest, firstly because up till now, system A was considered preferable for proline uptake in human fibroblasts, and secondly because they illustrate the need for combined inhibition and kinetic studies of amino acid uptake, especially when the substrate concentration range used and the respective Km of the systems do not allow their detection by kinetic analysis alone. Furthermore, this high-affinity system may have major physiological implications.     

Crystal structure of human PACRG in complex with MEIG1 reveals roles in axoneme formation and tubulin binding

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Phenotype Classification of Zebrafish Embryos by Supervised Learning

Zebrafish is increasingly used to assess biological properties of chemical substances and thus is becoming a specific tool for toxicological and pharmacological studies. The effects of chemical substances on embryo survival and development are generally evaluated manually through microscopic observation by an expert and documented by several typical photographs. Here, we present a methodology to automatically classify brightfield images of wildtype zebrafish embryos according to their defects by using an image analysis approach based on supervised machine learning. We show that, compared to manual classification, automatic classification results in 90 to 100% agreement with consensus voting of biological experts in nine out of eleven considered defects in 3 days old zebrafish larvae. Automation of the analysis and classification of zebrafish embryo pictures reduces the workload and time required for the biological expert and increases the reproducibility and objectivity of this classification.     

Cancer risk from chronic exposures to chemicals and radiation: a comparison of the toxicological reference value with the radiation detriment

This article aims at comparing reference methods for the assessment of cancer risk from exposure to genotoxic carcinogen chemical substances and to ionizing radiation. For chemicals, cancer potency is expressed as a toxicological reference value (TRV) based on the most sensitive type of cancer generally observed in animal experiments of oral or inhalation exposure. A dose–response curve is established by modelling experimental data adjusted to apply to human exposure. This leads to a point of departure from which the TRV is derived as the slope of a linear extrapolation to zero dose. Human lifetime cancer risk can then be assessed as the product of dose by TRV and it is generally considered to be tolerable in a 10^–6–10^–4 range for the public in a normal situation. Radiation exposure is assessed as an effective dose corresponding to a weighted average of energy deposition in body organs. Cancer risk models were derived from the epidemiological follow-up of atomic bombing survivors. Considering a linear-no-threshold dose-risk relationship and average baseline risks, lifetime nominal risk coefficients were established for 13 types of cancers. Those are adjusted according to the severity of each cancer type and combined into an overall indicator denominated radiation detriment. Exposure to radiation is subject to dose limits proscribing unacceptable health detriment. The differences between chemical and radiological cancer risk assessments are discussed and concern data sources, extrapolation to low doses, definition of dose, considered health effects and level of conservatism. These differences should not be an insuperable impediment to the comparison of TRVs with radiation risk, thus opportunities exist to bring closer the two types of risk assessment.

     

The Amusic Brain: Lost in Music,but Not in Space

Congenital amusia is a neurogenetic disorder of music processing that is currently ascribed to a deficit in pitch processing. A recent study challenges this view and claims the disorder might arise as a consequence of a general spatial-processing deficit. Here, we assessed spatial processing abilities in two independent samples of individuals with congenital amusia by using line bisection tasks (Experiment 1) and a mental rotation task (Experiment 2). Both amusics and controls showed the classical spatial effects on bisection performance and on mental rotation performance, and amusics and controls did not differ from each other. These results indicate that the neurocognitive impairment of congenital amusia does not affect the processing of space.     

Evidence for the activation of phospholipases during acrosome reaction of human sperm elicited by calcium ionophore A23187

Incubation of washed human sperm with [3H]- or [14C]arachidonic acid allowed a major incorporation of the label into phospholipids, provided that the final concentration of the fatty acid did not exceed 20 microM. A further challenge with calcium ionophore A23187 of spermatozoa suspended in a calcium-containing medium led to phospholipid hydrolysis, which could account for 10-12% of total cell radioactivity. Degradation products were identified as free, unconverted arachidonic acid, occurring with some diacylglycerol. Phospholipid hydrolysis was significant after 15 min of incubation and became maximal after 120 min. It was found to be calcium dependent, diacylglycerol and free arachidonate production occurring maximally at 2 mM and 5 mM CaCl2, respectively. Phosphatidylcholine and phosphatidylinositol were the most significantly degraded phospholipids after 60 min of incubation. Similar incubations conducted with 32P-labeled sperm confirmed the selective hydrolysis of phosphatidylcholine and revealed an increase production of phosphatidic acid probably due to a phosphorylation of diacylglycerol. Under the same conditions, one third of the cells remained motile and electron microscopy revealed that acrosome reaction was completed in 40% of the cells and displayed an intermediary state in 40-50% of the spermatozoa. Furthermore, a good parallelism was observed between the extent of the acrosome reaction and the extent of phospholipid hydrolysis promoted by increasing concentrations of A23187. It is concluded that calcium entry into the cells activates both a phospholipase A2 and a phospholipase C, leading to the production of substances, like lysophospholipid, diacylglycerol or phosphatidic acid, which may or may not be involved in acrosome reaction.