Factors Underlying the Early Limb Muscle Weakness in Acute Quadriplegic Myopathy Using an Experimental ICU Porcine Model

The basic mechanisms underlying acquired generalized muscle weakness and paralysis in critically ill patients remain poorly understood and may be related to prolonged mechanical ventilation/immobilization (MV) or to other triggering factors such as sepsis, systemic corticosteroid (CS) treatment and administration of neuromuscular blocking agents (NMBA). The present study aims at exploring the relative importance of these factors by using a unique porcine model. Piglets were all exposed to MV together with different combinations of endotoxin-induced sepsis, CS and NMBA for five days. Peroneal motor nerve conduction velocity and amplitude of the compound muscle action potential (CMAP) as well as biceps femoris muscle biopsy specimens were obtained immediately after anesthesia on the first day and at the end of the 5-day experimental period. Results showed that peroneal nerve motor conduction velocity is unaffected whereas the size of the CMAP decreases independently of the type of intervention, in all groups after 5 days. Otherwise, despite a preserved size, muscle fibre specific force (maximum force normalized to cross-sectional area) decreased dramatically for animals exposed to MV in combination with CS or/and sepsis. These results suggest that the rapid declines in CMAP amplitude and in force generation capacity are triggered by independent mechanisms with significant clinical and therapeutic implications

Age- and Temperature-Dependent Somatic Mutation Accumulation in Drosophila melanogaster

Using a transgenic mouse model harboring a mutation reporter gene that can be efficiently recovered from genomic DNA, we previously demonstrated that mutations accumulate in aging mice in a tissue-specific manner. Applying a recently developed, similar reporter-based assay in Drosophila melanogaster, we now show that the mutation frequency at the lacZ locus in somatic tissue of flies is about three times as high as in mouse tissues, with a much higher fraction of large genome rearrangements. Similar to mice, somatic mutations in the fly also accumulate as a function of age, but they do so much more quickly at higher temperature, a condition which in invertebrates is associated with decreased life span. Most mutations were found to accumulate in the thorax and less in abdomen, suggesting the highly oxidative flight muscles as a possible source of genotoxic stress. These results show that somatic mutation loads in short-lived flies are much more severe than in the much longer-lived mice, with the mutation rate in flies proportional to biological rather than chronological aging

Mosquito Feeding Affects Larval Behaviour and Development in a Moth

Organisms are attacked by different natural enemies present in their habitat. While enemies such as parasitoids and predators will kill their hosts/preys when they successfully attack them, enemies such as micropredators will not entirely consume their prey. However, they can still have important consequences on the performance and ecology of the prey, such as reduced growth, increased emigration, disease transmission

N-terminal amino-acid-sequence homology of storage protein-components from barley and a diploid wheat

Wild barley (Hordeum spontaneum) and the wild diploid wheat Triticum boeoticum were possibly the first plants cultivated by early man1, giving rise to the domesticated forms Hordeum vulgare L. and Triticum monococcum L. In addition, T. boeoticum may have contributed the A genome to polyploid wheats, including common bread wheat (Triticum aestivum)2 which is a hexaploid with genome composition ABD. Hordeum seems to be the older genus, having diverged from some common ancestor before the divergence of Triticum and other genera of the subtribe Triticinae3. Prolamins constitute the major storage protein fraction of both barley and wheat; they are located in the endosperm of the caryopsis and are soluble in alcohol–water solutions4. Barley and wheat prolamins (hordeins and gliadins, respectively) contain large amounts of glutamine and proline, which together make up 50–75 mol per cent of total amino acids4,5. The hordeins and gliadins are complex mixtures of components6–8 that seem to be encoded by clusters of duplicated genes that have diverged to produce many distinguishable protein components. Despite the complexity of the gliadin mixture, the components retain considerable homology in their N-terminal region9,10 and this has been reported for zeins, the prolamins of maize (Zea mays)11, as well. Here, we report that a purified C-hordein component from barley is homologous in amino acid sequence with a purified ω-gliadin component from T. monococcum at 23 of 27 residues at the N-terminus. This result is in accord with the close relationship between the two species and indicates that, despite the propensity of prolamin genes to tolerate mutations, a significant portion of their sequences can be conserved over a period of time, which, although not accurately known, probably amounts to millions of years.&nbsp