Abstract
Many radio galaxies show the presence of dense and dusty gas near the active nucleus. This can be traced by both 21 cm H i absorption and soft X-ray absorption, offering new insight into the ...physical nature of the circumnuclear medium of these distant galaxies. To better understand this relationship, we investigate soft X-ray absorption as an indicator for the detection of associated H i absorption, as part of preparation for the First Large Absorption Survey in H i to be undertaken with the Australian Square Kilometre Array Pathfinder (ASKAP). We present the results of our pilot study using the Boolardy Engineering Test Array, a precursor to ASKAP, to search for new absorption detections in radio sources brighter than 1 Jy that also feature soft X-ray absorption. Based on this pilot survey, we detected H i absorption towards the radio source PKS 1657−298 at a redshift of z = 0.42. This source also features the highest X-ray absorption ratio of our pilot sample by a factor of 3, which is consistent with our general findings that X-ray absorption predicates the presence of dense neutral gas. By comparing the X-ray properties of active galactic nuclei with and without detection of H i absorption at radio wavelengths, we find that X-ray hardness ratio and H i absorption optical depth are correlated at a statistical significance of 4.71σ. We conclude by considering the impact of these findings on future radio and X-ray absorption studies.
•We examined whether groups that differ in the activity of catechol-O-methyltransferase (COMT), either genetically or as the result of a pharmacological challenge, show differences in regional ...cerebral blood flow (CBF).•COMT genotype influenced frontal CBF, whilst COMT inhibition altered CBF in parietal and temporal regions.•Our findings demonstrate that both acute and trait differences in dopamine signalling influence regional CBF.•We recommend the inclusion of CBF measures in fMRI studies of the impact of dopaminergic manipulations on BOLD signal.
Dopamine has direct and complex vasoactive effects on cerebral circulation. Catechol-O-methyltransferase (COMT) regulates cortical dopamine, and its activity can be influenced both genetically and pharmacologically. COMT activity influences the functional connectivity of the PFC at rest, as well as its activity during task performance, determined using blood oxygen level-dependent (BOLD) fMRI. However, its effects on cerebral perfusion have been relatively unexplored. Here, 76 healthy males, homozygous for the functional COMT Val158Met polymorphism, were administered either the COMT inhibitor tolcapone or placebo in a double-blind, randomised design. We then assessed regional cerebral blood flow at rest using pulsed arterial spin labelling. Perfusion was affected by both genotype and drug. COMT genotype affected frontal regions (Val158 > Met158), whilst tolcapone influenced parietal and temporal regions (placebo > tolcapone). There was no genotype by drug interaction. Our data demonstrate that lower COMT activity is associated with lower cerebral blood flow, although the regions affected differ between those affected by genotype compared with those altered by acute pharmacological inhibition. The results extend the evidence for dopaminergic modulation of cerebral blood flow. Our findings also highlight the importance of considering vascular effects in functional neuroimaging studies, and of exercising caution in ascribing group differences in BOLD signal solely to altered neuronal activity if information about regional perfusion is not available.
A pH-driven DNA nanomachine based on the human α-thrombin binding aptamer was designed for the specific catch-and-release of human α-thrombin at neutral and acidic pH, respectively. In neutral ...conditions, the thrombin aptamer component of the nanomachine is exposed and exists in the G-quadruplex conformation required to bind to the target protein. At slightly acidic pH, the polyadenine tail of the nanomachine becomes partially protonated and A+(anti)•G(syn) mispairing results in a conformational change, causing the target protein to be released. Förster resonance energy transfer (FRET) was used to monitor conformational switching over multiple pH cycles. Electrophoretic mobility shift assay (EMSA) and fluorescence anisotropy were used to show pH dependent protein binding and release by the nanomachine. This approach could be applied generally to existing G-rich aptamers to develop novel biosensors, theranostics, and nanoswitches.
The primary goal of this pilot feasibility study was to examine the effects of Mindfulness-Oriented Recovery Enhancement (MORE), a behavioral treatment grounded in dual-process models derived from ...cognitive science, on frontostriatal reward processes among cigarette smokers. Healthy adult (N=13; mean (SD) age 49 ± 12.2) smokers provided informed consent to participate in a 10-week study testing MORE versus a comparison group (CG). All participants underwent two fMRI scans: pre-tx and after 8-weeks of MORE. Emotion regulation (ER), smoking cue reactivity (CR), and resting-state functional connectivity (rsFC) were assessed at each fMRI visit; smoking and mood were assessed throughout. As compared to the CG, MORE significantly reduced smoking (d=2.06) and increased positive affect (d=2.02). MORE participants evidenced decreased CR-BOLD response in ventral striatum (VS; d=1.57) and ventral prefrontal cortex (vPFC; d=1.7) and increased positive ER-BOLD in VS (dVS=2.13) and vPFC (dvmPFC=2.66). Importantly, ER was correlated with smoking reduction (r’s = .68 to .91) and increased positive affect (r’s = .52 to .61). These findings provide preliminary evidence that MORE may facilitate the restructuring of reward processes and play a role in treating the pathophysiology of nicotine addiction.
Summary
Background
Human skin has the crucial roles of maintaining homeostasis and protecting against the external environment. Skin offers protection against mechanical trauma due to the reversible ...deformation of its structure; these biomechanical properties are amenable to dynamic testing using noninvasive devices.
Objectives
To characterize the biomechanical properties of young, black African/African‐Caribbean and white Northern European skin from different anatomical sites, and to relate underlying skin architecture to biomechanical function.
Methods
Using cutometry and ballistometry, the biomechanical properties of buttock and dorsal forearm skin were determined in black African/African‐Caribbean (n = 18) and white Northern European (n = 20) individuals aged 18–30 years. Skin biopsies were obtained from a subset of the volunteers (black African/African‐Caribbean, n = 5; white Northern European, n = 6) and processed for histological and immunohistochemical detection of the major elastic fibre components and fibrillar collagens.
Results
We have determined that healthy skin from young African and white Northern European individuals has similar biomechanical properties (F3): the skin is resilient (capable of returning to its original position following deformation, R1), exhibits minimal fatigue (R4) and is highly elastic (R2, R5 and R7). At the histological level, skin with these biomechanical properties is imbued with strong interdigitation of the rete ridges at the dermoepidermal junction (DEJ) and candelabra‐like arrays of elastic fibres throughout the papillary dermis. Dramatic disruption to this highly organized arrangement of elastic fibres, effacement of the rete ridges and alterations to the alignment of the fibrillar collagens is apparent in the white Northern European forearm and coincides with a marked decline in biomechanical function.
Conclusions
Maintenance of skin architecture – both epidermal morphology and elastic fibre arrangement – is essential for optimal skin biomechanical properties. Disruption to underlying skin architecture, as observed in the young white Northern European forearm, compromises biomechanical function.
What's already known about this topic?
Human skin offers protection against the external environment via the reversible deformation of its structure: the stratum corneum and components of the dermal extracellular matrix imbue skin with these important biomechanical properties.
Skin biomechanical properties are amenable to dynamic testing in vivo using the noninvasive methods of cutometry and ballistometry.
What does this study add?
This study combines in vivo testing of black African and white Northern European skin with the histological assessment of skin biopsies in order to interrogate the relationship between underlying skin architecture and biomechanical function.
Disruption to skin architecture, particularly loss of oxytalan fibres and effacement of rete ridges, correlates with perturbation of biomechanical function.
What is the translational message?
Quantitative measurement of biomechanical properties combined with histological assessment of underlying extracellular matrix architecture are useful tools to provide us with an understanding of skin's normal functions.
These techniques may be useful to examine the clinical progression of skin conditions that affect skin elasticity and provide objective measurement of the efficacy of treatment options designed to improve skin health.
Respond to this article
Linked Comment: Dobrev. Br J Dermatol 2017; 177:622–623
Plain language summary available online
•LPS injection induces social avoidance in female mice.•LPS induces cytokine expression in both males and females.•LPS increases alcohol intake in both males and females.•Neurokinin-1 receptor ...antagonism reduces LPS-induced escalation in alcohol intake.
Much recent research has demonstrated a role of inflammatory pathways in depressive-like behavior and excess alcohol consumption. Lipopolysaccharide (LPS) is a cell wall component of gram-negative bacteria that can be used to trigger a strong inflammatory response in rodents in a preclinical research setting to study the mechanisms behind this relationship. In our study, we exposed male and female mice to LPS and assessed depressive-like behavior using the social interaction (SI) test, alcohol consumption in the two-bottle choice procedure, and expression of inflammatory mediators using quantitative PCR. We found that LPS administration decreased SI in female mice but had no significant impact on male mice when assessed 24 h after injection. LPS resulted in increased proinflammatory cytokine expression in both male and female mice; however, some aspects of the cytokine upregulation observed was greater in female mice as compared to males. A separate cohort of male and female mice underwent drinking for 12 days before receiving a saline or LPS injection, which we found to increase alcohol intake in both males and females. We have previously observed a role of the neurokinin-1 receptor (NK1R) in escalated alcohol intake, and in the inflammatory and behavioral response to LPS. The NK1R is the endogenous target of the neuropeptide SP, and this system has wide ranging roles in depression, anxiety, drug/alcohol seeking, pain, and inflammation. Thus, we administered a NK1R antagonist prior to alcohol access. This treatment reduced escalated alcohol consumption in female mice treated with LPS but did not affect drinking in males. Taken together, these results indicate that females are more sensitive to some physiological and behavioral effects of LPS administration, but that LPS escalates alcohol consumption in both sexes. Furthermore, NK1R antagonism can reduce alcohol consumption that is escalated by LPS treatment, in line with our previous findings.
The belowground effects of Phytophthora cinnamomi on 1‐year‐old saplings of two common oak species in mid‐Atlantic US forests, white (Quercus alba) and red oak (Q. rubra), were examined after ...incubation in pathogen‐infested soilless potting mix. Fine root lengths (0–1.5 mm in diameter) of both oak species were quantified after incubation at successive 30‐day intervals up to 300 days, for a total of 10 incubation periods. In addition, colony‐forming units (CFU) of P. cinnamomi were quantified after white oak saplings were incubated in infested soilless potting mix at different temperature/duration combinations that reflect soil conditions present in the mid‐Atlantic United States. Impact of P. cinnamomi on fine root lengths of red and white oak saplings varied considerably over time. Significant periods of fine root loss occurred primarily during spring, when bud break and leaf flush began for both oak species. Red oaks had 17% fine root loss on average, while white oaks appeared more resistant to P. cinnamomi infection with a 2% decrease in fine roots over the course of the experiment. Phytophthora cinnamomi CFU declined significantly with exposure to all incubation temperatures except 8°C. This was in contrast to in vitro experiments, where the optimum temperature for mycelial growth was determined to be 21°C and above. Significant fine root loss caused by P. cinnamomi depended on plant phenology and the oak species tested. Extreme soil temperatures have a significant adverse impact on temporal changes of P. cinnamomi population.
ABSTRACT
Obscuration of quasars by accreted gas and dust, or dusty intervening galaxies, can cause active galactic nuclei (AGN) to be missed in optically selected surveys. Radio observations can ...overcome this dust bias. In particular, radio surveys searching for H i absorption inform us on how the AGN can impact on the cold neutral gas medium within the host galaxy, or the population of intervening galaxies through the observed line of sight gas kinematics. We present the results of an H i absorption line survey at 0.4 < z < 1 towards 34 obscured quasars with the Australian SKA Pathfinder (ASKAP) commissioning array. We detect three H i absorption lines, with one of these systems previously unknown. Through optical follow-up for two sources, we find that in all detections the H i gas is associated with the AGN, and hence that these AGN are obscured by material within their host galaxies. Most of our sample are compact, and in addition, are either gigahertz peaked spectrum (GPS), or steep spectrum (CSS) sources, both thought to represent young or recently re-triggered radio AGN. The radio spectral energy distribution classifications for our sample agree with galaxy evolution models in which the obscured AGN has only recently become active. Our associated H i detection rate for GPS and compact SS sources matches those of other surveys towards such sources. We also find shallow and asymmetric H i absorption features, which agrees with previous findings that the cold neutral medium in compact radio galaxies is typically kinematically disturbed by the AGN.
PDF
