Meteorological influences on respirable fragment release from Chinese elm pollen

Exposure to airborne pollen from certain plants can cause allergic disease, leading to acute respiratory symptoms. Whole pollen grains, 15–90 μ m-sized particles, provoke the upper respiratory symptoms of rhinitis (hay fever), while smaller pollen fragments capable of depositing in the lower respiratory tract have been proposed as the trigger for asthma. In order to understand factors leading to pollen release and fragmentation we have examined the rupture of Chinese elm pollen under controlled laboratory conditions and in the outdoor atmosphere. Within 30 minutes after immersion in water, 70% of fresh Chinese pollen ruptures, rapidly expelling cytoplasm. Chinese elm flowers, placed in a controlled atmosphere chamber, emitted pollen and pollen debris after a sequential treatment of 98% relative humidity followed by drying and a gentle disturbance. Immunologic assays of antigenic proteins specific to elm pollens revealed that fine particulate material (D p < 2 μ m) collected from the chamber contained elm pollen antigens. In a temporal study of the outdoor urban atmosphere during the Chinese elm bloom season of 2004, peak concentrations of pollen and fine pollen fragments occurred at the beginning of the season when nocturnal relative humidity (RH) exceeded 90%. Following later periods of hot dry weather, pollen counts decreased to zero. The Chinese elm pollen fragments also decreased during the hot weather, but later displayed additional peaks following periods of more moderate RH and temperature, indicating that pollen counts underestimate total atmospheric pollen allergen concentrations. Pollen fragments thus increase the biogenic load in the atmosphere in a form that is no longer recognizable as pollen and, therefore, is not amenable to microscopic analysis. This raises the possibility of exposure of sensitive individuals to pollen allergens in the form of fine particles that can penetrate into the lower airways and pose potentially severe health risks.

Uncoupling the mechanisms that facilitate cell survival in hormone-deprived bovine mammary explants

Mammary explants can be hormonally stimulated to mimic the biochemical changes that occur during lactogenesis. Previous studies using mammary explants concluded that the addition of exogenous macromolecules were required for mammary epithelial cells to remain viable in culture. The present study examines the survival of mammary explants from the dairy cow using milk protein gene expression as a functional marker of lactation and cell viability. Mammary explants cultured from late pregnant cows mimicked lactogenesis and showed significantly elevated milk protein gene expression after 3 days of culture with lactogenic hormones. The subsequent removal of exogenous hormones from the media for 10 days resulted in the down-regulation of milk protein genes. During this time, the mammary explants remained hormone responsive, the alveolar architecture was maintained and the expression of milk protein genes was re-induced after a second challenge with lactogenic hormones. We report that a population of bovine mammary epithelial cells have an intrinsic capacity to remain viable and hormone responsive for extended periods in chemically defined media without any exogenous macromolecules. In addition, we found mammary explant viability was dependent on de novo protein and RNA synthesis. Global functional microarray analysis showed that differential expression of genes involved in energy production, immune responses, oxidative stress and apoptosis signalling might contribute to cell survival. As the decline in milk production in dairy cattle after peak lactation results in considerable economic loss, the identification of novel survival genes may be used as genetic markers for breeding programmes to improve lactational persistency in dairy cows.

Sprint cycling performance is maintained with short-term contrast water immersion

Purpose: Given the widespread use of water immersion during recovery from exercise, we aimed to investigate the effect of contrast water immersion on recovery of sprint cycling performance, HR and, blood lactate.

Methods: Two groups completed high-intensity sprint exercise before and after a 30-min randomized recovery. The Wingate group (n = 8) performed 3 x 30-s Wingate tests (4-min rest periods). The repeated intermittent sprint group (n = 8) cycled for alternating 30-s periods at 40% of predetermined maximum power and 120% maximum power, until exhaustion. Both groups completed three trials using a different recovery treatment for each trial (balanced randomized application). Recovery treatments were passive rest, 1:1 contrast water immersion (2.5 min of cold (8-C) to 2.5 min of hot (40-C)), and 1:4 contrast water immersion (1 min of cold to 4 min of hot). Blood lactate and HR were recorded throughout, and peak power and total work for pre- and postrecovery Wingate performance and exercise time and total work for repeated sprinting were recorded.

Results: Recovery of Wingate peak power was 8% greater after 1:4 contrast water immersion than after passive rest, whereas both contrast water immersion ratios provided a greater recovery of exercise time (È10%) and total work (È14%) for repeated sprinting than for passive rest. Blood lactate was similar between trials. Compared with passive rest, HR initially declined more slowly during contrast water immersion but increased with each transition to a cold immersion phase.

Conclusions: These data support contrast water immersion being effective in maintaining performance during a short-term recovery from sprint exercise. This effect needs further investigation but is likely explained by cardiovascular mechanisms, shown here by an elevation in HR upon each cold immersion.

A comparison of the classification of disparate malware collected in different time periods

It has been argued that an anti-virus strategy based on malware collected at a certain date, will not work at a later date because malware evolves rapidly and an anti-virus engine is faced with a completely new type of executable not as amenable to detection as the first was. In this paper, we test this idea by collecting two sets of malware, the first from 2002 to 2007, the second from 2009 to 2010 to determine how well the anti-virus strategy we developed based on the earlier set [14] will do on the later set. This anti-virus strategy integrates dynamic and static features extracted from the executables to classify malware by distinguishing between families. The resulting classification accuracies are very close for both datasets, with a difference of only 5.4%, the older malware being more accurately classified than the newer malware. This leads us to conjecture that current anti-virus strategies can indeed be modified to deal effectively with new malware.

A comparison of the classification of disparate malware collected in different time periods

It has been argued that an anti-virus strategy based on malware collected at a certain date, will not work at a later date because malware evolves rapidly and an anti-virus engine is then faced with a completely new type of executable not as amenable to detection as the first was.

In this paper, we test this idea by collecting two sets of malware, the first from 2002 to 2007, the second from 2009 to 2010 to determine how well the anti-virus strategy we developed based on the earlier set [18] will do on the later set. This anti-virus strategy integrates dynamic and static features extracted from the executables to classify malware by distinguishing between families. We also perform another test, to investigate the same idea whereby we accumulate all the malware executables in the old and new dataset, separately, and apply a malware versus cleanware classification.

The resulting classification accuracies are very close for both datasets, with a difference of approximately 5.4% for both experiments, the older malware being more accurately classified than the newer malware. This leads us to conjecture that current anti-virus strategies can indeed be modified to deal effectively with new malware.

Industry self regulation of television food advertising : responsible or responsive?

Introduction. This study evaluated the impact of the Australian Food and Grocery Council (AFGC) self-regulatory initiative on unhealthy food marketing to children, introduced in January 2009. The study compared patterns of food advertising by AFGC and non-AFGC signatory companies in 2009, 2007 and 2006 on three Sydney commercial free-to-air television channels.

Methods. Data were collected across seven days in May 2006 and 2007, and four days in May 2009. Advertised foods were coded as core, non-core and miscellaneous. Regression for counts analyses was used to examine change in rates of advertisements across the sampled periods and differential change between AFGC-signatory or non-signatory companies between 2007 and 2009.

Results. Of 36 food companies that advertised during the 2009 sample period, 14 were AFGC signatories. The average number of food advertisements decreased significantly from 7.0 per hour in 2007 to 5.9 in 2009. There was a significant reduction in non-core food advertising from 2007 to 2009 by AFGC signatories compared with non-signatory companies overall and during peak times, when the largest numbers of children were viewing. There was no reduction in the rate of non-core food advertisements by all companies, and these advertisements continue to comprise the majority during peak viewing times.

Discussion. While some companies have responded to pressures to reduce unhealthy food advertising on television, the impact of the self-regulatory code is limited by the extent of uptake by food companies. The continued advertising of unhealthy foods indicates that this self-regulatory code does not adequately protect children.

Differential corticosteroid receptor regulation of mesoaccumbens dopamine efflux during the peak and nadir of the circadian rhythm : a molecular equilibrium in the midbrain?

Corticosteroid receptor modulation of mesoaccumbens dopamine neurotransmission is believed to be a key neurobiological mechanism mediating the effects of stress in addiction. Importantly, nucleus accumbens (NAc) subregions (core and shell) are reported to respond differentially to fluctuating basal levels of glucocorticoids, with dopaminergic responses in the core of the NAc being somewhat impervious to fluctuating levels of glucocorticoids relative to the shell. To investigate the corticosteroid receptor mechanisms mediating basal dopamine efflux in the core of the NAc, we have used chronoamperometry in combination with stearate-modified graphite paste electrodes in urethane anesthetized male Long–Evans rats during the peak and nadir of the circadian cycle. Blockade of ventral tegmental area low-affinity glucocorticoid (GR) or high-affinity mineralocorticoid (MR) receptors with mifepristone (1 μg/μl) or spironolactone (0.2 μg/μl), respectively, indicated that endogenous phase-dependent corticosteroid receptor activation (GRs during peak; MRs during nadir) facilitated extracellular NAc dopamine efflux. Conversely, the alternate receptor's actions appeared inhibitory at these time points (MRs during peak; GRs during nadir). Pharmacological activation of either the GR or MR with corticosterone (2 μg/μl) or aldosterone (0.2 μg/μl), respectively, potentiated NAc dopamine efflux, irrespective of circadian phase. Together, these data suggest that dominant corticosteroid receptor activation stimulates tonic mesoaccumbens dopamine transmission, enabling MRs and GRs to differentially maintain basal NAc dopamine release over the course of the circadian cycle. This points to an important molecular mechanism through which relatively stable NAc core dopamine extracellular levels could be maintained in the face of fluctuating corticosterone circadian rhythms.

Peak picking and the assessment of separation performance in two-dimensional high performance liquid chromatography

An algorithm was developed for 2DHPLC that automated the process of peak recognition, measuring their retention times, and then subsequently plotting the information in a two-dimensional retention plane. Following the recognition of peaks, the software then performed a series of statistical assessments of the separation performance, measuring for example, correlation between dimensions, peak capacity and the percentage of usage of the separation space. Peak recognition was achieved by interpreting the first and second derivatives of each respective one-dimensional chromatogram to determine the 1D retention times of each solute and then compiling these retention times for each respective fraction ‘cut’. Due to the nature of comprehensive 2DHPLC adjacent cut fractions may contain peaks common to more than one cut fraction. The algorithm determined which components were common in adjacent cuts and subsequently calculated the peak maximum profile by interpolating the space between adjacent peaks. This algorithm was applied to the analysis of a two-dimensional separation of an apple flesh extract separated in a first dimension comprising a cyano stationary phase and an aqueous/THF mobile phase as the first dimension and a second dimension comprising C18-Hydro with an aqueous/MeOH mobile phase. A total of 187 peaks were detected.

Energetic cost of bot fly parasitism in free-ranging eastern chipmunks

The energy and nutrient demands of parasites on their hosts are frequently invoked as an explanation for negative impacts of parasitism on host survival and reproductive success. Although cuterebrid bot flies are among the physically largest and most-studied insect parasites of mammals, the only study conducted on metabolic consequences of bot fly parasitism revealed a surprisingly small effect of bot flies on host metabolism. Here we test the prediction that bot fly parasitism increases the resting metabolic rate (RMR) of free-ranging eastern chipmunks (Tamias striatus), particularly in juveniles who have not previously encountered parasites and have to allocate energy to growth. We found no effect of bot fly parasitism on adults. In juveniles, however, we found that RMR strongly increased with the number of bot fly larvae hosted. For a subset of 12 juveniles during a year where parasite prevalence was particularly high, we also compared the RMR before versus during the peak of bot fly prevalence, allowing each individual to act as its own control. Each bot fly larva resulted in a ~7.6% increase in the RMR of its host while reducing juvenile growth rates. Finally, bot fly parasitism at the juvenile stage was positively correlated with adult stage RMR, suggesting persistent effects of bot flies on RMR. This study is the first to show an important effect of bot fly parasitism on the metabolism and growth of a wild mammal. Our work highlights the importance of studying cost of parasitism over multiple years in natural settings, as negative effects on hosts are more likely to emerge in periods of high energetic demand (e.g. growing juveniles) and/or in harsh environmental conditions (e.g. low food availability).

Timing of breeding and diet of the Black-faced cormorant Phalacrocorax fuscescens

Previous anecdotal reports have suggested that Black-faced Cormorant Phalacrocorax fuscescens breeds only in winter in southeastern Australia, but detailed reports confirming this are lacking. Here we examine the timing of breeding in Black-faced Cormorants at Notch Island in northern Bass Strait in 2006. Peak laying occurred during winter (ca 26 July). The diet of Black-faced Cormorants was predominantly fish (97% of identified prey) and varied between breeding and post-breeding periods. Black-faced Cormorants consumed a total of 14 different species with four species having a frequency of occurrence in the diet of ?5% during the breeding season and six species during the post-breeding period. We provide data for the first time on the chronology of breeding of Black-faced Cormorants in one year and give a preliminary description of their diet based on pellet analyses. We propose that late winter breeding may be a strategy to avoid the high ambient temperatures in northern Bass Strait during summer, the associated higher thermoregulatory costs for adults and the increased mortality for chicks.

Peak oxygen uptake of 12-18-year-old boys living in a densely populated urban environment

The purposes of this study were to provide data on the peak Vo 2 of 12-18-year-old boys from Hong Kong, a densely populated urban environment; to compare these data with those for other similarly aged populations; and to examine the correlations between peak Vo 2 and various anthropometric parameters of this group. A stratified, random sample of 86 ethnic Chinese boys had their peak Vo 2 determined using an on-line gas analysis system during incremental, treadmill running. The mean peak 17o2 of the boys was 2.7 SD 0.44 1- rain - 1 or, when expressed in relation to body mass, 52.0 SD 5-8 ml- kg- 1. min - 1. Peak Vo 2 (1. min - 1) was significantly correlated with body mass (r = 0.72, p < 0.001, age (r = 0.49, p < 0.001) and height (r = 0.71, p = 0-001). Peak Vo 2 (ml 'kg- 1. min- 1) showed no correlation with age or height. These data suggest that this population group has peak Vo 2 values very similar to those observed in boys from most other population groups.

A preliminary study of the 20-m multistage shuttle run as a predictor of peak VO2 in Hong Kong Chinese students

The purpose of the present study was to determine the validity of the 20-meter multistage shuttle run (MSR) for predicting peak VO2 in Hong Kong Chinese students, ages 12-15 years. Fifty-five subjects, 27 boys and 28 girls, performed the MSR in the school environment and had peak VO2 determined in the laboratory. A correlation of 0.72 (p is less than 0.001) was found between peak VO2 and predicted peak VO2 using an equation previously developed with Canadian children (6). However, maximal shuttle run speed alone was a better predictor in this group (r=0.74, SEE=4.6 ml.kg-1.min-1, p is less than 0.001). Multiple-regression analysis (best-subsets) was performed and the best predictor variables were maximal speed and sex with either triceps skinfold or weight. For practical application in the school setting, the equation peak VO2=24.2-5.0(sex) minus 0.8(age) plus 3.4(maximal speed) (r=0.82, SEE=4.0), where for sex, male = 0 and female = 1, is suggested.