Time budgets of grassland herbivores: body size similarities

The summer (May–September) time budgets of 14 generalist herbivore species living in the same grassland environment are presented in terms of various component activities (e.g., walking, feeding, resting, etc.). All the species exhibit a decrease in activity as average daily air temperature increases. Greater body size and variety of habitats used by a species lead to increased time spent active. Use of a greater variety of habitats may increase activity time because different habitats provide suitable thermal conditions for activity at different times of the day. Body size affects sn herbivore's thermal balance through metabolism, body surface area and thermal inertia. The time spent feeding, exclusive of time spent searching for foods, is less for large than small herbivores. This may arise because large species must spend more time walking in the search for food to satisfy their energy requirements. The observed feeding time differences for species composing a common trophic level in a single environment may help to explain their diet choice because feeding time constrains the variety of foods an herbivore can select. Diet differences, in turn, can explain the potential competition for food if food is in short supply.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47766/1/442_2004_Article_BF00377110.pd

Aortic-Valve Infection - Risk-Factors for Death and Recurrent Endocarditis After Aortic-Valve Replacement

Patients (n = 195) undergoing aortic valve replacement (n = 209) for native or prosthetic valve endocarditis were studied to determine risk factors for death and recurrent endocarditis and also to determine the valve type least likely to be associated with recurrent endocarditis. Ten-year survival was 60 %, the highest risk of dying occurring within the first 3 postoperative months. Risk factors for death in this early phase included increased urea concentration, higher New York Heart Association functional class, prosthetic valve endocarditis, infection status (lower in patients with healed endocarditis), longer duration of cardiopulmonary bypass, and nonuse of an allograft valve. In the late phase (beyond 3 months), risk factors included age at operation and Staphylococcus aureus infection (only in New York Heart Association functional class V). Ten years after aortic valve replacement, 79 % of valves were free of recurrent endocarditis. The highest risk of recurrence was in the first 4 months. Longer duration of cardiopulmonary bypass was a weak risk factor for recurrent endocarditis in the early phase, and in the late phase risk factors were S. aureus infection (only in New York Heart Association functional classes III, IV, and V) and the use of now discontinued biologic valves. Allograft aortic valve replacement was shown to be associated with a low and constant risk of recurrent endocarditis, whereas other valve types were associated with a high early risk. The allograft valve should be the preferred replacement device for aortic root infection

Effects of aging on apoptosis gene expression in oral mucosal tissues

Apoptotic processes are important for physiologic renewal of an intact epithelial barrier and contribute some antimicrobial resistance for bacteria and viruses, as well as anti-inflammatory effects that benefits the mucosa. The oral cavity presents a model of host-bacterial interactions at mucosal surfaces, in which a panoply of microorganisms colonizes various niches in the oral cavity and creates complex multispecies biofilms that challenge the gingival tissues. This report details gene expression in apoptotic pathways that occur in oral mucosal tissues across the lifespan, using a nonhuman primate model. Macaca mulatta primates from 2 to 23 years of age (n = 23) were used in a cross-sectional study to obtain clinical healthy gingival tissues specimens. Further, mRNA was prepared and evaluated using the Affymetrix Rhesus GeneChip and 88 apoptotic pathway genes were evaluated. The results identified significant positive correlations with age in 12 genes and negative correlations with an additional five genes. The gene effects were predicted to alter apoptosis receptor levels, extrinsic apoptotic pathways through caspases, cytokine effects on apoptotic events, Ca(+2)-induced death signaling, cell cycle checkpoints, and potential effects of survival factors. Both the positively and negatively correlated genes within the apoptotic pathways provided evidence that healthy tissues in aging animals exhibit decreased apoptotic potential compared to younger animals. The results suggested that decreased physiologic apoptotic process in the dynamic septic environment of the oral mucosal tissues could increase the risk of aging tissues to undergo destructive disease processes through dysregulated inflammatory responses to the oral microbial burden