Gene-centric metagenomics of the fiber-adherent bovine rumen microbiome reveals forage specific glycoside hydrolases.

The complex microbiome of the rumen functions as an effective system for the conversion of plant cell wall biomass to microbial protein, short chain fatty acids, and gases. As such, it provides a unique genetic resource for plant cell wall degrading microbial enzymes that could be used in the production of biofuels. The rumen and gastrointestinal tract harbor a dense and complex microbiome. To gain a greater understanding of the ecology and metabolic potential of this microbiome, we used comparative metagenomics (phylotype analysis and SEED subsystems-based annotations) to examine randomly sampled pyrosequence data from 3 fiber-adherent microbiomes and 1 pooled liquid sample (a mixture of the liquid microbiome fractions from the same bovine rumens). Even though the 3 animals were fed the same diet, the community structure, predicted phylotype, and metabolic potentials in the rumen were markedly different with respect to nutrient utilization. A comparison of the glycoside hydrolase and cellulosome functional genes revealed that in the rumen microbiome, initial colonization of fiber appears to be by organisms possessing enzymes that attack the easily available side chains of complex plant polysaccharides and not the more recalcitrant main chains, especially cellulose. Furthermore, when compared with the termite hindgut microbiome, there are fundamental differences in the glycoside hydrolase content that appear to be diet driven for either the bovine rumen (forages and legumes) or the termite hindgut (wood).

Sleep onset insomnia symptoms during hospitalization for major burn injury predict chronic pain.

Both cross-sectional studies of chronic pain and sleep deprivation experiments suggest a bi-directional relationship between sleep and pain. Few longitudinal studies, however, have assessed whether acute insomnia following traumatic injury predicts the development of persistent pain. We sought to evaluate (1) whether in-hospital insomnia independently predicts long-term pain after burn injury and (2) whether in-hospital pain predicts future insomnia symptoms. We analyzed data on 333 subjects hospitalized for major burn injury (72.7% male; mean age=41.1+/-14.5years) who were participating in the multi-site, Burn Model System project. Subjects completed measures of health, function (SF-36), and psychological distress (Brief Symptom Inventory) while in hospital, at 6, 12, and 24months after discharge. Participants were categorized as either having or not having sleep onset insomnia at discharge. Linear mixed effects analyses revealed that persons reporting insomnia at discharge (40.5%) had significantly decreased improvement in pain and increased pain severity during long-term follow-up (p<0.001). More severe pain during the week preceding hospital discharge, time from injury, lack of college education and older age also contributed independent effects on chronic pain (p<0.05). In a reciprocal model (N=299), more severe pain during the week preceding discharge predicted increased rates of long-term sleep onset insomnia. In-hospital insomnia and pre-burn mental health symptoms were also highly significant predictors of insomnia. This study provides support for a long-term, prospective and reciprocal interaction between insomnia and pain. Future work should ascertain whether treatment of insomnia and pain during acute injury can prevent or minimize chronic pain.