Envenomations by Bothrops and Crotalus Snakes Induce the Release of Mitochondrial Alarmins

Skeletal muscle necrosis is a common manifestation of viperid snakebite envenomations. Venoms from snakes of the genus Bothrops, such as that of B. asper, induce muscle tissue damage at the site of venom injection, provoking severe local pathology which often results in permanent sequelae. In contrast, the venom of the South American rattlesnake Crotalus durissus terrificus, induces a clinical picture of systemic myotoxicity, i.e., rhabdomyolysis, together with neurotoxicity. It is known that molecules released from damaged muscle might act as ‘danger’ signals. These are known as ‘alarmins’, and contribute to the inflammatory reaction by activating the innate immune system. Here we show that the venoms of B. asper and C. d. terrificus release the mitochondrial markers mtDNA (from the matrix) and cytochrome c (Cyt c) from the intermembrane space, from ex vivo mouse tibialis anterior muscles. Cyt c was released to a similar extent by the two venoms whereas B. asper venom induced the release of higher amounts of mtDNA, thus reflecting hitherto some differences in their pathological action on muscle mitochondria. At variance, injection of these venoms in mice resulted in a different time-course of mtDNA release, with B. asper venom inducing an early onset increment in plasma levels and C. d. terrificus venom provoking a delayed release. We suggest that the release of mitochondrial ‘alarmins’ might contribute to the local and systemic inflammatory events characteristic of snakebite envenomations

Biofeedback and progressive relaxation treatment of sleep-onset insomnia

Previous research suggests that self-defined insomniacs are distinguished from normals by high levels of anxiety and physiological arousal, which might be mitigated by muscle relaxation. This study assessed the relative effects of frontal EMG biofeedback, progressive relaxation, and a placebo set of “relaxation” exercises on the sleep of 18 onset insomniacs. Each subject was trained in one of these three methods for six half-hour sessions and slept in the laboratory for two consecutive nights before and after training. The experimental groups demonstrated significant decreases in physiological activity during training while changes in the control group were minimal. Reductions in sleep-onset time were: biofeedback group, 29.66 minutes; progressive relaxation group, 22.92 minutes; control group, 2.79 minutes. The experimental groups improved significantly ( p<.05 ) more than the control group, but did not differ from each other. No significant relationships between physiological levels and sleep-onset time were found, which suggests that muscle relaxation alone was not responsible for subjects' improvements. Since 20 minutes of daily practice were required to achieve an approximate 30-minute decrease in sleep-onset time, the practical utility of the methods is questioned.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44085/1/10484_2005_Article_BF01001167.pd

Unusual Microbial Xylanases from Insect Guts

Recombinant DNA technologies enable the direct isolation and expression of novel genes from biotopes containing complex consortia of uncultured microorganisms. In this study, genomic libraries were constructed from microbial DNA isolated from insect intestinal tracts from the orders Isoptera (termites) and Lepidoptera (moths). Using a targeted functional assay, these environmental DNA libraries were screened for genes that encode proteins with xylanase activity. Several novel xylanase enzymes with unusual primary sequences and novel domains of unknown function were discovered. Phylogenetic analysis demonstrated remarkable distance between the sequences of these enzymes and other known xylanases. Biochemical analysis confirmed that these enzymes are true xylanases, which catalyze the hydrolysis of a variety of substituted β-1,4-linked xylose oligomeric and polymeric substrates and produce unique hydrolysis products. From detailed polyacrylamide carbohydrate electrophoresis analysis of substrate cleavage patterns, the xylan polymer binding sites of these enzymes are proposed