Cross-Protection of Influenza A Virus Infection by a DNA Aptamer Targeting the PA Endonuclease Domain

Amino acid residues in the N-terminal of the PA subunit (PA_N) of the influenza A virus polymerase play critical roles in endonuclease activity, protein stability, and viral RNA (vRNA) promoter binding. In addition, PA_N is highly conserved among different subtypes of influenza virus, which suggests PA_N to be a desired target in the development of anti-influenza agents. We selected DNA aptamers targeting the intact PA protein or the PA_N domain of an H5N1 virus strain using systematic evolution of ligands by exponential enrichment (SELEX). The binding affinities of selected aptamers were measured, followed by an evaluation of in vitro endonuclease inhibitory activity. Next, the antiviral effects of enriched aptamers against influenza A virus infections were examined. A total of three aptamers targeting PA and six aptamers targeting PA_N were selected. Our data demonstrated that all three PA-selected aptamers neither inhibited endonuclease activity nor exhibited antiviral efficacy, whereas four of the six PA_N-selected aptamers inhibited both endonuclease activity and H5N1 virus infection. Among the four effective aptamers, one exhibited cross-protection against infections of H1N1, H5N1, H7N7, and H7N9 influenza viruses, with a 50% inhibitory concentration (IC₅₀) of around 10 nM. Notably, this aptamer was identified at the 5th round but disappeared after the 10th round of selection, suggesting that the identification and evaluation of aptamers at early rounds of selection may be highly helpful for screening effective aptamers. Overall, our study provides novel insights for screening and developing effective aptamers for use as anti-influenza drugs.     

Individual versus Standardized Running Protocols in the Determination of VO2max

The purpose of this study was to determine whether an individually designed incremental exercise protocol results in greater rates of oxygen uptake (VO_2max) than standardized testing. Fourteen well-trained, male runners performed five incremental protocols in randomized order to measure their VO_2max: i) an incremental test (INC_S+I) with pre-defined increases in speed (2 min at 8.64 km·h⁻¹, then a rise of 1.44 km·h⁻¹ every 30 s up to 14.4 km·h⁻¹) and thereafter inclination (0.5° every 30 s); ii) an incremental test (INC_I) at constant speed (14.4 km·h⁻¹) and increasing inclination (2° every 2 min from the initial 0°); iii) an incremental test (INC_S) at constant inclination (0°) and increasing speed (0.5 km·h⁻¹ every 30 s from the initial 12.0 km·h⁻¹); iv) a graded exercise protocol (GXP) at a 1° incline with increasing speed (initially 8.64 km·h⁻¹ + 1.44 km·h⁻¹ every 5 min); v) an individual exercise protocol (INDXP) in which the runner chose the inclination and speed. VO_2max was lowest (-4.2%) during the GXP (p = 0.01; d = 0.06-0.61) compared to all other tests. The highest rating of perceived exertion, heart rate, ventilation and end-exercise blood lactate concentration were similar between the different protocols (p < 0.05). The time to exhaustion ranged from 7 min 18 sec (INC_S) to 25 min 30 sec (GXP) (p = 0.01).The VO_2max attained by employing an individual treadmill protocol does not differ from the values derived from various standardized incremental protocols.

Key points

• The mean maximum oxygen uptake during the GXP was lower than for all other tests.
• Differences in the maximum rate of oxygen uptake between the various protocols exhibited considerable inter-individual variation.
• From the current findings, it can be concluded that well trained athletes are able to perform an individually designed treadmill running protocol.

Key words: Maximum oxygen uptake, aerobic power, treadmill running, ramp test, treadmill protocol     

Interaction of microbes with mucus and mucins

Due to the recent rapid expansion in our understanding of the composition of the gut microflora and the consequences of altering that composition the question of how bacteria colonise mucus layers and interact with components of mucus, such as mucin, is now receiving widespread attention. Using a combination of mucus secreting cells, and a novel mucin microarray platform containing purified native mucins from different sources we recently demonstrated that two gastrointestinal pathogens, Helicobacter pylori and Campylobacter jejuni, colonise mucus by different mechanisms. This result emphasizes the potential for even closely related bacteria to interact with mucus in divergent ways to establish successful infection. Expanding the use of the mucin arrays described in the study to other microorganisms, both pathogenic and commensal, should lead to the discovery of biologically important motifs in bacterial-host interactions and complement the use of novel in vitro cell models, such as mucus secreting cell lines.     

Effect of pregnancy on immunological and virological outcomes of women on ART: a prospective cohort study in rural Uganda, 2004-2009

Objectives Before antiretroviral therapy (ART) introduction, pregnancy was associated with a sustained drop in CD4 cell count in HIV‐infected women. We examined the effects of pregnancy on immunological and virological ART outcomes. Methods Between January 2004 and March 2009, we studied HIV‐infected women receiving ART in a prospective open cohort study in rural Uganda. We used random effects regression models to compare the CD4 counts of women who became pregnant and those who did not, and among the pregnant women before and after pregnancy. CD4 count and proportions with detectable viral load (≥400 copies/ml) were compared between the two groups using the Mann–Whitney rank sum test and logistic regression respectively. Results Of 88 women aged 20–40 years receiving ART, 23 became pregnant. At ART initiation, there were no significant differences between those who became pregnant and those who did not in clinical, immunological and virological parameters. Among women who became pregnant, CD4 cell count increased before pregnancy (average 75.9 cells/mm³ per year), declined during pregnancy (average 106.0) but rose again in the first year after delivery (average 88.6). Among women who did not become pregnant, the average CD4 cell count rise per year for the first 3 years was 88.5. There was no significant difference in the proportions of women with detectable viral load at last clinic visit among those who became pregnant (8.7%) and those who did not (16.1%), P = 0.499. Conclusion Pregnancy had no lasting effect on the immunological and virological outcomes of HIV‐infected women on ART.     

Assessment of leptomeningeal collaterals using dynamic CT angiography in patients with acute ischemic stroke

Whole-brain dynamic time-resolved computed tomography angiography (CTA) is a technique developed on the new 320-detector row CT scanner capable of generating time-resolved cerebral angiograms from skull base to vertex. Unlike a conventional cerebral angiogram, this technique visualizes pial arterial filling in all vascular territories, thereby providing additional hemodynamic information. Ours was a retrospective study of consecutive patients with ischemic stroke and M1 middle cerebral artery +/−intracranial internal carotid artery occlusions presenting to our center from June 2010 and undergoing dynamic time-resolved CTA and perfusion CT within 6 hours of symptom onset. Leptomeningeal collateral status was assessed by determining relative prominence of pial arteries in the ischemic region, rate and extent of retrograde flow, and various topographical patterns of pial arterial filling. Twenty-five patients were included in the study. We demonstrate the existence of the following novel properties of leptomeningeal collaterals in humans: (a) posterior (posterior cerebral artery (PCA)–MCA) dominant collateralization, (b) intra-territorial ‘within MCA region'' leptomeningeal collaterals, and (c) significant variability in size, extent, and retrograde filling time in pial arteries. We also describe a simple and reliable collateral grading template that, for the first time on dynamic CTA, incorporates back-filling time as well as size and extent of collateral filling.     

Trauma and current symptoms of PTSD in a South East London community

Purpose

This study aimed to estimate the prevalence of symptoms of post-traumatic stress disorder (PTSD) and its association with traumatic events in a representative sample of an inner city population in the UK.

Methods

A representative community sample of 1,698 adults, aged 16 years and over, from two south London boroughs were interviewed face to face with structured survey questionnaires.

Results

The prevalence of current symptoms of PTSD was 5.5 %. Women were more likely to screen positive (6.4 %) than men (3.6 %), and symptoms of PTSD were high in the unemployed (12.5 %), in those not working because of health reasons (18.2 %) and in the lowest household income group (14.8 %). Most (78.2 %) of the study population had lifetime trauma and more than a third (39.7 %) reported childhood trauma. There was an independent association between childhood as well as lifetime trauma and current symptoms of PTSD and a gradient association between an increase in cumulative traumatic events and the likelihood of reporting symptoms of current PTSD (OR 1.8, 95 % CI (1.6–2.1)). Although we observed the highest prevalence of current symptoms of PTSD in those migrated for asylum or political reason (13.6 %), compared to the non-migrants, the prevalence of exposure to most traumatic life events was higher in the non-migrant group.

Conclusion

The present study demonstrates the high prevalence of exposure to trauma in a South East London community and the cumulative effect on current symptoms of PTSD. As PTSD is a condition which is associated with disability and co-morbidity, the association of current PTSD with common adversities in the community should be noted.