Variation in the neonate size of Daphnia pulex: the effects of predator exposure and clonal origin

Daphnia pulex clones originating from twelve small pond habitats were exposed to chemical cues from a size-selective predator, larvae of the phantom midge Chaoborus. Exposure delayed the onset of reproduction and increased the size at first reproduction. On the other hand, the neonates produced by these larger mothers were slightly smaller than the neonates produced by the smaller control mothers. In cladocerans, neonate size is usually positively correlated to the size of the mother. Thus exposure to Chaoborus kairomone apparently had direct effects on neonate size counterbalancing the maternal effects. Daphnia clones collected from Chaoborus-free and Chaoborus-rich environments exhibited different responses. In first adult instar, the clones from Chaoborus inhabited environments increased their offspring size under Chaoborus exposure whereas clones from Chaoborus-free environments did not. This may reflect clonal adaptation to the predation prehistory of their original habitat since larger neonates more quickly reach a size protected from the predator.     

Dental and Microbiological Risk Factors for Hospital-Acquired Pneumonia in Non-Ventilated Older Patients

Hospital acquired pneumonia (HAP) is often fatal in older patients. The mouth is the main reservoir of infection and studies have suggested that oral hygiene interventions may prevent HAP. The aim of this study was to investigate associations between HAP and preceding a) heavy dental plaque and b) oral carriage of potential respiratory pathogens in older patients with lower limb fracture to determine the target for intervention studies.

Methods

We obtained a time series of tongue/throat swabs from 90 patients with lower limb fracture, aged 65-101 in a general hospital in the North East of England between April 2009-July 2010. We used novel real-time multiplex PCR assays to detect S. aureus, MRSA, E. coli, P. aeruginosa, S. pneumoniae, H. influenza and Acinetobacter spp. We collected data on dental/denture plaque (modified Quigley-Hein index) and outcomes of clinician-diagnosed HAP.

Results

The crude incidence of HAP was 10% (n = 90), with mortality of 80% at 90 days post discharge. 50% of cases occurred within the first 25 days. HAP was not associated with being dentate, tooth number, or heavy dental/denture plaque. HAP was associated with prior oral carriage with E. coli/S. aureus/P.aeruginosa/MRSA (p = 0.002, OR 9.48 95% CI 2.28-38.78). The incidence of HAP in those with carriage was 35% (4% without), with relative risk 6.44 (95% CI 2.04-20.34, p = 0.002). HAP was associated with increased length of stay (Fishers exact test, p=0.01), with mean 30 excess days (range -11.5-115). Target organisms were first detected within 72 hours of admission in 90% participants, but HAP was significantly associated with S. aureus/MRSA/P. aeruginosa/E. coli being detected at days 5 (OR 4.39, 95%CI1.73-11.16) or 14 (OR 6.69, 95%CI 2.40-18.60).

Conclusions

Patients with lower limb fracture who were colonised orally with E. coli/ S. aureus/MRSA/P. aeruginosa after 5 days in hospital were at significantly greater risk of HAP (p = 0.002).     

Relative vs. absolute physiological measures as predictors of mountain bike cross-country race performance

The aims of this study were to document the effect terrain has on the physiological responses and work demands (power output) of riding a typical mountain bike cross-country course under race conditions. We were particularly interested in determining whether physiological measures relative to mass were better predictors of race performance than absolute measures. Eleven A-grade male cross-country mountain bike riders (VO2max 67.1 +/- 3.6 ml x kg(-1) x min(-1)) performed 2 tests: a laboratory-based maximum progressive exercise test, and a 15.5-km (six 2.58-km laps) mountain bike cross-country time trial. There were significant differences among the speed, cadence, and power output measured in each of 8 different terrain types found in the cross-country time trial course. The highest average speed was measured during the 10-15% downhill section (22.7 +/- 2.6 km x h(-1)), whereas the cadence was highest in the posttechnical flat sections (74.3 +/- 5.6 rpm) and lowest on the 15-20% downhill sections (6.4 +/- 12.1 rpm). The highest mean heart rate (HR) was obtained during the steepest (15-20% incline) section of the course (179 +/- 8 b x min(-1)), when the power output was greatest (419.8 +/- 39.7 W). However, HR remained elevated relative to power output in the downhill sections of the course. Physiological measures relative to total rider mass correlated more strongly to average course speed than did absolute measures (peak power relative to mass r = 0.93, p < 0.01, vs. peak power r = 0.64, p < 0.05; relative VO2max r = 0.80, p < 0.05, vs. VO2max r = 0.66, p < 0.05; power at anaerobic threshold relative to mass r = 0.78, p < 0.05, vs. power at anaerobic threshold r = 0.5, p < 0.05). This suggests that mountain bike cross-country training programs should focus upon improving relative physiological values rather than focusing upon maximizing absolute values to improve performance.     

Identification of serum N-acetylmuramoyl-l-alanine amidase as liver peptidoglycan recognition protein 2

N-acetylmuramoyl-l-alanine amidase (NAMLAA) hydrolyzes bacterial peptidoglycan and is present in human serum. A peptidoglycan-recognition protein 2 (PGLYRP2) is expressed in human liver and has N-acetylmuramoyl-l-alanine amidase activity. Here, we determined the amino acid sequences of human serum NAMLAA and liver PGLYRP2 and tested the hypothesis that serum NAMLAA and PGLYRP2 are the same protein. Liver PGLYRP2 and serum NAMLAA had the same mass determined by mass spectrometry and polyacrylamide gel electrophoresis, and both proteins and recombinant PGLYRP2 reacted with polyclonal anti-NAMLAA and anti-PGLYRP2 antibodies, and with monoclonal anti-NAMLAA antibodies. Digestion of serum NAMLAA with trypsin, chymotrypsin, or trypsin plus V8 protease, or with CNBr yielded, respectively, 37, 40, and 3 overlapping peptides that matched 100% and covered 81% of the deduced amino acid sequence of mature PGLYRP2. These peptides overlapped all exon-intron junctions indicating no alternative splice forms. Digestion of liver PGLYRP2 with trypsin yielded 23 peptides that matched 100% and covered 44% of the deduced amino acid sequence of mature PGLYRP2. Serum NAMLAA had a C398-C404 disulfide, partial phosphorylation of S218, and deamidation of N253 and N301. These results indicate that serum NAMLAA and liver PGLYRP2 are the same protein encoded by the pglyrp2 gene.     

Food insecurity and increased BMI in young adult women

Food insecurity has been associated with weight status in children and adults although results have been mixed. We aimed to identify whether food insecurity was associated with BMI in young adults and whether this association differed by gender and was modified by food stamp use and the presence of children in the home. Cross-sectional data from wave 4 (2007-2008) of the National Longitudinal Study of Adolescent Health were analyzed. Multiple linear regression was used to investigate the association between food insecurity and BMI in gender stratified models of young adult women (n = 7,116) and men (n = 6,604) controlling for age, race/ethnicity, income, education, physical activity, smoking, alcohol use, the presence of children in the home, and food stamp use in young adulthood and/or adolescence. Food insecurity was more common in young adult women (14%) than young adult men (9%). After controlling for a variety of individual variables, food insecure women had a BMI that was on average 0.9 kg/m(2) units higher than women who were food secure. This difference in BMI persisted after controlling for recent or past food stamp use and was not different among women with or without children in the household. No relationship was found between food insecurity and BMI in young adult men. Providers should inquire about food insecurity, especially when treating obesity, and policy initiatives should address the role of access to healthy food in those facing food insecurity.     

A CMOS Image Sensor Integrated with Plasmonic Colour Filters

Multi-pixel, 4.5?×?9???m, plasmonic colour filters, consisting of periodic subwavelength holes in an aluminium film, were directly integrated on the top surface of a complementary metal oxide semiconductor (CMOS) image sensor (CIS) using electron beam lithography and dry etch. The 100?×?100-pixel plasmonic CIS showed full colour sensitivities across the visible range determined by a photocurrent measurement. The filters were fabricated in a simple process utilising a single lithography step. This is to be compared with the traditional multi-step processing when using dye-doped polymers. The intrinsic compatibility of these plasmonic components with a standard CMOS process allows them to be manufactured in a metal layer close to the photodiodes. The incorporation of such plasmonic components may in the future enable the development of advanced CIS with low cost, low cross-talk and increased functionality.     

Synthesis and biological evaluation of a fluorescent analog of phenytoin as a potential inhibitor of neuropathic pain and imaging agent

Here we report on a novel fluorescent analog of phenytoin as a potential inhibitor of neuropathic pain with potential use as an imaging agent. Compound 2 incorporated a heptyl side chain and dansyl moiety onto the parent compound phenytoin and produced greater displacement of BTX from sodium channels and greater functional blockade with greatly reduced toxicity. Compound 2 reduced mechano-allodynia in a rat model of neuropathic pain and was visualized ex vivo in sensory neuron axons with two-photon microscopy. These results suggest a promising strategy for developing novel sodium channel inhibitors with imaging capabilities.     

The impact of experimental sedimentation and flooding on the growth and germination of floodplain trees

Land-use changes in a forested floodplain’s watershed can lead to incremental changes in the hydrology and sedimentation rates of the floodplain. The impacts of these changes can be difficult to measure due to the slow response time of mature trees. Seedlings and saplings, on the other hand, may show an immediate response. Responses during these early life history stages can have major consequences for regeneration of floodplain forests and ultimately result in community alteration. This study tested the importance of changes in hydrology and sedimentation on the germination and growth rates of three common floodplain tree species: Acer rubrum, Fraxinus pennsylvanica and Quercus palustris. Two-year-old saplings were grown in a greenhouse under two hydrologic regimes, with or without the addition of sediment. Neither periodic flooding with or without sediment nor static flooding on its own affected the growth of the seedlings. With the addition of sediment, static flooding for two weeks lead to a significant decrease in sapling growth. There was a significant species x treatment interaction, suggesting that each species responded differently to the application of flooding and sediment. The timing of germination and the total percent germination for F. pennsylvanica and Q. palustris seeds were tested under the same conditions. Flooding and sediment acted in an additive manner to delay the germination of both F. pennsylvanica and Q. palustris and to reduce the total germination rate of Q. palustris. There was no difference in the total germination rate of F. pennsylvanica seeds under any treatment. During the growth trials, adventitious roots sprouted on saplings grown under sedimentation. Adventitious roots growing into sediment rather than floodwater should be able to utilize the sediment’s nutrients and may compensate for some of the stress of flooding. The results of this study suggest that sediment tolerances will vary among species, but will not necessarily correlate with flood tolerances, and that sedimentation may be as important as flooding in determining floodplain plant community composition.