Effects of a Heated Anesthesia Breathing Circuit on Body Temperature in Anesthetized Rhesus Macaques (Macaca mulatta).

This study evaluated the effects of using a heated anesthesia breathing circuit in addition to forced-air warming on body temperature in anesthetized rhesus macaques as compared with forced-air warming alone. Hypothermia is a common perianesthetic and intraoperative complication that can increase the risk of negative outcomes. Body heat is lost through 4 mechanisms during anesthesia: radiation, conduction, convection, and evaporation. Typical warming methods such as forced-air warming devices, conductive heating pads, and heated surgical tables only influence radiative and conductive mechanisms of heat loss. A commercially available heated breathing circuit that delivers gas warmed to 104 °F can easily be integrated into an anesthesia machine. We hypothesized that heating the inspired anesthetic gas to address the evaporative mechanism of heat loss would result in higher body temperature during anesthesia in rhesus macaques. Body temperatures were measured at 5-min intervals in a group of 10 adult male rhesus macaques during 2 anesthetic events: one with a heated anesthesia breathing circuit in addition to forced-air warming, and one with forced-air warming alone. The addition of a heated breathing circuit had a significant positive effect on perianesthetic body temperature, with a faster return to baseline temperature, earlier nadir of initial drop in body temperature, and higher body temperatures during a 2-h anesthetic procedure. Use of a heated anesthesia breathing circuit should be considered as a significant refinement to thermal support during macaque anesthesia, especially for procedures lasting longer than one hour.

Moonlighting proteins: putting the spotlight on enzymes.

AROGENATE DEHAYDRATASE2 (ADT2) is a member of the Arabidopsis thaliana ADT family. All members of this family act as arogenate dehydratases in phenylalanine biosynthesis, decarboxylating/dehydrating arogenate to phenylalanine. ADT2 is detected in stromules, and as a ring around the equatorial plane of dividing chloroplasts, indicating it has a second, non-enzymatic function in chloroplast division. Here, we provide further evidence for this alternative role of ADT2. First, we demonstrate that ADT2 and FtsZ co-localize around the equatorial plane at the same time. Second, FtsZ expression in an adt2 mutant was analyzed, as well as ADT2 expression in three Arabidopsis chloroplast division mutants, ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3), ARC5 and ARC6. In arc3 and arc6 mutants, ADT2 is misexpressed and resembles the expression of FtsZ in the same mutants. However, in the arc5 mutant, ADT2 ring positioning is observed at constriction points indicating proper relative timing. ADT2 expression in the arc mutants shows that the role of ADT2 in chloroplast division occurs prior to ARC5, but is dependent on ARC3 and ARC6. Abbreviations used: ADT: arogenate dehydratase, ARC: accumulation and replication of chloroplasts, CFP: cyan fluorescent protein, dpi: days post infiltration, FtsZ: filamentous temperature sensitive Z, PD: plastid division, Phe: phenylalanine, YFP: yellow fluorescent protein.

Assessing Energy Level as a Marker of Aerobic Exercise Readiness: A Pilot Investigation.

Energy ratings have been used as a marker of exercise readiness (i.e. pre-exercise physical/mental state indicating ability to perform) within flexible nonlinear periodization (FNLP)-based resistance training interventions. However, empirical data is lacking regarding the utility of this approach for aerobic exercise. The purpose of this study was to examine the ability of pre-exercise energy level to predict affective and behavioral responses to prescribed aerobic exercise. Participants consisted of 19 women and 8 men (N=27, age=20±4 years, estimated maximal oxygen uptake=37±6). Participants performed two 30-min bouts of treadmill exercise under an imposed moderate intensity (70-75% of age-predicted maximal heart rate; %HRmax) condition and a self-selected intensity condition. Pre-exercise energy level was assessed using the Energy Index (EI) score derived from the Profile of Mood States. Feeling Scale (FS) was the dependent variable in the imposed bout and average intensity (%HRmax) was the dependent variable during the self-selected bout. Multiple regression analyses were used to determine if EI predicted mean FS and %HRmax. After controlling for potential confounders, EI significantly predicted mean FS (ß=.499, p=.037) during imposed exercise. No significant relationship existed between EI and overall intensity (ß =-121, p=.554) during self-selected exercise. While EI predicted in-task core affect it was unrelated to self-selected intensity. It is premature to suggest EI as an optimal predictor of exercise readiness in regards to aerobic exercise for aerobically untrained young adults. More research is needed to determine an evidence-based marker of readiness that can be used for aerobic exercise prescribed within the context of FNLP.

Chickadees Faced with Unpredictable Food Increase Fat Reserves but Certain Components of Their Immune Function Decline.

In winter, temperate resident birds are often faced with periodic low natural food availability. This reduction or unpredictability in resource availability might then have a negative impact on immune function, given that immune system support is highly resource dependent. We investigated the balance between energetic and immune management in captive black-capped chickadees (Poecile atricapilus) by manipulating the predictability of resources. The control group received food ad lib. every day, while the experimental group received a reduced amount of food on random days and food ad lib. on all other days. We measured two key metrics of energetic management (body and fat mass) as well as a suite of immune system components. Compared with control birds, experimental birds maintained significantly higher total body and fat mass, had lower acute phase protein concentrations, and had decreased body temperature and lost more body mass during the fever response following injection with lipopolysaccharides. Interestingly, birds in both groups had similar levels of complement lysis, delayed-type hypersensitivity response (phytohemagglutinin), and primary antibody production (keyhole limpet hemocyanin). This experiment demonstrates that black-capped chickadees strategically increase their fat mass in response to decreased food availability and that this might allow the birds to maintain most of the immune system unaltered, except some of the most costly immune components.

Co-extinction in a host-parasite network: identifying key hosts for network stability.

Parasites comprise a substantial portion of total biodiversity. Ultimately, this means that host extinction could result in many secondary extinctions of obligate parasites and potentially alter host-parasite network structure. Here, we examined a highly resolved fish-parasite network to determine key hosts responsible for maintaining parasite diversity and network structure (quantified here as nestedness and modularity). We evaluated four possible host extinction orders and compared the resulting co-extinction dynamics to random extinction simulations; including host removal based on estimated extinction risk, parasite species richness and host level contributions to nestedness and modularity. We found that all extinction orders, except the one based on realistic extinction risk, resulted in faster declines in parasite diversity and network structure relative to random biodiversity loss. Further, we determined species-level contributions to network structure were best predicted by parasite species richness and host family. Taken together, we demonstrate that a small proportion of hosts contribute substantially to network structure and that removal of these hosts results in rapid declines in parasite diversity and network structure. As network stability can potentially be inferred through measures of network structure, our findings may provide insight into species traits that confer stability.