Antarctic permafrost degassing in Taylor Valley by extensive soil gas investigation.

Ongoing studies conducted in northern polar regions reveal that permafrost stability plays a key role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emissions, both from physical and microbial processes. The potential impact of greenhouse gas release from the Antarctic region has not, to date, been investigated. In Antarctica, the McMurdo Dry Valleys comprise 10 % of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit at a slower rate. The work presented herein examines a comprehensive sample suite of soil gas (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in Taylor Valley during austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CO2, CH4 and He (up to 3.44 vol%, 18,447 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increased CO2 flux rates (estimated CO2 emissions in the study area of 21.6 km2 ≈ 15 tons day-1). We suggest that the gas source is connected with the deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emissions from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.

Stepped-wedge cluster randomised controlled trial to assess the effectiveness of an electronic medication management system to reduce medication errors, adverse drug events and average length of stay at two paediatric hospitals: a study protocol.

INTRODUCTION: Medication errors are the most frequent cause of preventable harm in hospitals. Medication management in paediatric patients is particularly complex and consequently potential for harms are greater than in adults. Electronic medication management (eMM) systems are heralded as a highly effective intervention to reduce adverse drug events (ADEs), yet internationally evidence of their effectiveness in paediatric populations is limited. This study will assess the effectiveness of an eMM system to reduce medication errors, ADEs and length of stay (LOS). The study will also investigate system impact on clinical work processes. METHODS AND ANALYSIS: A stepped-wedge cluster randomised controlled trial (SWCRCT) will measure changes pre-eMM and post-eMM system implementation in prescribing and medication administration error (MAE) rates, potential and actual ADEs, and average LOS. In stage 1, 8 wards within the first paediatric hospital will be randomised to receive the eMM system 1 week apart. In stage 2, the second paediatric hospital will randomise implementation of a modified eMM and outcomes will be assessed. Prescribing errors will be identified through record reviews, and MAEs through direct observation of nurses and record reviews. Actual and potential severity will be assigned. Outcomes will be assessed at the patient-level using mixed models, taking into account correlation of admissions within wards and multiple admissions for the same patient, with adjustment for potential confounders. Interviews and direct observation of clinicians will investigate the effects of the system on workflow. Data from site 1 will be used to develop improvements in the eMM and implemented at site 2, where the SWCRCT design will be repeated (stage 2). ETHICS AND DISSEMINATION: The research has been approved by the Human Research Ethics Committee of the Sydney Children's Hospitals Network and Macquarie University. Results will be reported through academic journals and seminar and conference presentations. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ANZCTR) 370325.

Foliar-Applied Small Molecule that Suppresses Biofilm Formation and Enhances Control of Copper-Resistant Xanthomonas euvesicatoria on Pepper.

We report a small molecule additive, a member of the 2-aminoimidazole (2AI) group that is an analogue of the marine sponge natural product oroidin that suppresses resistance of Xanthomonas euvesicatoria to copper and decreases biofilm formation in an in vitro system. In laboratory experiments, 2AI combined with copper reduced both bacterial multiplication in broth and bacterial recovery on pepper leaf discs of a copper-resistant strain of X. euvesicatoria to a level close to that of a copper-sensitive strain. Compound 2AI used alone exhibited minimal bactericidal activity. In 3 years of field experiments, when combined with a copper-containing material, copper hydroxide (Kocide 3000), and other antibacterial materials, these spray mixtures resulted in decreased bacterial spot foliar disease and increased fruit yields using hybrid bell pepper (Capsicum annuum) cultivars and copper-resistant strains of X. euvesicatoria. This study demonstrates the concept for using small molecules as additives to antibacterial compounds at nonbactericidal concentrations under field conditions that, in the laboratory, were demonstrated to suppress bacterial biofilms and copper-resistant strains.

Clinical issues on consent: some philosophical concerns.

On occasions, laws on consent are subject to modification, largely on account of being subject to common law rather than statute-for example, in the UK. Guideline publications such as the UK Department of Health Reference Guide to Consent for Examination or Treatment are intended to provide information for clinicians on when and how to apply current laws in everyday clinical situations. While the extent to which guidelines influence clinician behaviour depends on how much they are read and followed, what is also relevant, and sometimes omitted from consideration, is discussion about underlying philosophical concepts. This paper analyses philosophical weaknesses relating to English laws on consent, the main focus of attention being applied ethics and the rights of adults with incapacity. It draws comparisons between the US and the UK, and advocates changes in English law in order to help rectify weaknesses in patient protection. Discussion includes references to Scottish law, and the use of advance directives, and it voices concerns about over-reliance on "best interests" determinations. The problem is partly one of logical analysis, and what can happen is that best interests determinations fail to show proper respect for adults lacking the capacity to consent to examination or treatment on their own behalf. This is fundamentally a matter of rights, and requires further investigation and appropriate legal remedies in order to respond to ethical deficiencies in English law as it now stands.

Point mutations confer loss of ATP-induced human P2X(7) receptor function.

Residues considered essential for ATP binding to the human P2X(7) receptor (hP2X(7)R) were investigated. HEK293 cells or Xenopus oocytes were transfected with wild-type or site-directed mutants of hP2X(7)R constructs and channel/pore activity measured in the presence of ATP or 2',3'-O-(4-benzoylbenzoyl)-ATP (BzATP). Barium uptake and ethidium influx into HEK293 cells were abolished in cells expressing K193A and K311A mutants, and were partially reduced in cells expressing mutant P210A. K193A and K311A mutations also completely abolished responses to ATP and BzATP in Xenopus oocytes as measured by electrophysiology. These results indicate that K193 and K311 are essential residues in ATP binding in the hP2X(7)R.

A Glu-496 to Ala polymorphism leads to loss of function of the human P2X7 receptor.

The P2X(7) receptor is a ligand-gated cation-selective channel that mediates ATP-induced apoptosis of cells of the immune system. We and others have shown that P2X(7) is nonfunctional both in lymphocytes and monocytes from some subjects. To study a possible genetic basis we sequenced DNA coding for the carboxyl-terminal tail of P2X(7). In 9 of 45 normal subjects a heterozygous nucleotide substitution (1513A-->C) was found, whereas 1 subject carried the homozygous substitution that codes for glutamic acid to alanine at amino acid position 496. Surface expression of P2X(7) on lymphocytes was not affected by this E496A polymorphism, demonstrated both by confocal microscopy and immunofluorescent staining. Monocytes and lymphocytes from the E496A homozygote subject expressed nonfunctional receptor, whereas heterozygotes showed P2X(7) function that was half that of germline P2X(7). Results of transfection experiments showed that the mutant P2X(7) receptor was nonfunctional when expressed at low receptor density but regained function at a high receptor density. This density dependence of mutant P2X(7) function was also seen on differentiation of fresh monocytes to macrophages with interferon-gamma, which up-regulated mutant P2X(7) and partially restored its function. P2X(7)-mediated apoptosis of lymphocytes was impaired in homozygous mutant P2X(7) compared with germline (8.6 versus 35.2%). The data suggest that the glutamic acid at position 496 is required for optimal assembly of the P2X(7) receptor.

Fighting from the right side of the brain: left visual field preference during aggression in free-ranging male tree lizards (Urosaurus ornatus).

In a field study on male tree lizards (Urosaurus ornatus), we tested the hypothesis that aggression is lateralized, and predicted that resident males should preferentially use the left-visual field (LVF)/right hemisphere in aggressive interactions with other males. This prediction was based on results for a small but taxonomically diverse number of vertebrates indicating a left-eye preference/ right hemisphere specialization for aggression. Many lizards use postural displays to signal aggression and lateral eye placement prevents binocular vision of such displays. The fullshow is an aggressive display that is typically performed with the body held perpendicular to that of the opponent. We staged male-male encounters by introducing stimulus males to free-ranging males (hereafter called focal males), and then recorded both the focal male's behavior and the visual field that he used to view the intruder while performing fullshow displays. When intruders were introduced in the right visual field (RVF), focal males were equally likely to use either the LVF or RVF to perform their first fullshow. However, in these RVF introductions focal males were more likely to turn and use the LVF if the intruder was smaller. In contrast to RVF introductions, in LVF introductions focal males were significantly more likely than expected by chance to continue to use the LVF to view the intruder when performing the first fullshow. Furthermore, if focal males performed their first fullshow with the intruder in their LVF, they subsequently gave more aggressive displays than focal males that performed their first display with the intruder in their RVF. Additionally, charge (a highly aggressive behavior that usually leads to direct physical contact and a bite) was significantly more likely to occur while the LVF was being used to view the opponent. These results are consistent with the hypothesis that aggression is lateralized to the right hemisphere. This study is one of only a few examples of laterality of brain function demonstrated in a free-ranging vertebrate.

A review of the infectious diseases of African wild ruminants.

The important viral, protozoal and bacterial diseases of wild African ruminants are reviewed. Special attention is paid to the epidemiological factors that determine the role played by these animals in the transmission of diseases to domestic stock. Examples of the converse situation where livestock serve as a source of infection for wild ruminants are also given.

Residual erythroid progenitors in W/W mice respond to erythropoietin in the absence of steel factor signals.

Erythropoiesis is severely impaired in mice with inactivating mutations in the Steel factor (SF) gene (Sl/Sl mice) or in c-kit, in the SF receptor gene (W/W mice), and in mice with null mutations in the genes for either erythropoietin (EPO) or the erythropoietin receptor (EPO-R). Previous studies indicated that EPO is sufficient for colony development from colony-forming units-erythroid (CFU-E). However, recent studies have shown that there is a physical association between these 2 receptors and that c-kit can phosphorylate EPO-R. To examine the role SF and EPO play in regulating erythropoiesis, we examined the effect of SF and EPO on colony development from cells of the embryonic aorta-gonad-mesonephros (AGM) region, yolk sac, and liver of fetal wild-type and W/W mice. The maturation of CFU-E from these sites did not require the addition of SF to clonal cultures, whereas the efficient development of erythroid bursts required both EPO and SE The number of erythroid colony-forming cells was reduced in both the AGM region and liver of fetal W/W mice. The residual CFU-E present in W/W mice were dependent on EPO and independent of SF. These results indicate that EPO/EPO-R can function to support colony formation in the absence of an SF signal.

Breakdown of stabilization of atoms interacting with intense, high-frequency laser pulses

An analysis of the influence of the magnetic field of an intense, high-frequency laser pulse on the stabilization of an atomic system is presented. We demonstrate that at relatively modest intensities the magnetic field can significantly alter the dynamics of the system. In particular, a breakdown of stabilization occurs, thereby restricting the intensity regime in which the atom is relatively stable against ionization. Counterpropagating pulses do not negate the detrimental effects of the magnetic field. We compare our quantum mechanical results with classical Monte Carlo simulations.

P2X(1) receptor membrane redistribution and down-regulation visualized by using receptor-coupled green fluorescent protein chimeras.

The P2X(1) purinergic receptor subtype occurs on smooth muscle cells of the vas deferens and urinary bladder where it is localized in two different size receptor clusters, with the larger beneath autonomic nerve terminal varicosities. We have sought to determine whether these synaptic-size clusters only form in the presence of varicosities and whether they are labile when exposed to agonists. P2X(1) and a chimera of P2X(1) and green fluorescent protein (GFP) were delivered into cells using microinjection, transient transfection or infection with a replication-deficient adenovirus. The P2X(1)-GFP chimera was used to study the time course of P2X(1) receptor clustering in plasma membranes and the internalization of the receptor following prolonged exposure to ATP. Both P2X(1) and P2X(1)-GFP clustered in the plasma membranes of Xenopus oocytes, forming patches 4-6 microm in diameter. Human embryonic kidney 293 (HEK293) cells, infected with the adenovirus, possessed P2X(1) antibody-labeled regions in the membrane colocalized with GFP fluorescence. The ED(50) for the binding of alpha,beta-methylene adenosine triphosphate (alpha,beta-meATP) to the P2X(1)-GFP chimera was similar to native P2X(1) receptors. ATP-generated whole-cell currents in oocytes or HEK293 cells expressing either P2X(1) or P2X(1)-GFP were similar. Exposure of HEK293 cells to alpha, beta-meATP for 10-20 min in the presence of 5 microM monensin led to the disappearance of P2X(1)-GFP fluorescence from the surface of the cells. These observations using the P2X(1)-GFP chimera demonstrate that P2X(1) receptors spontaneously form synaptic-size clusters in the plasma membrane that are internalized on exposure to agonists.

Localisation of P2X receptors in human salivary gland epithelial cells and human embryonic kidney cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blotting and immunofluorescence.

Human salivary gland epithelial cells, a continuous cell line derived from an irradiated human salivary gland and human embryonic kidney cell line human embryonic kidney (HEK)293 were examined for the purpose of establishing whether they expressed endogenous P2X ionotropic receptors at any stage in their cycles. HSG cells were found to express P2X1-6 subtypes using both Western blotting and immunofluorescence labeling. HEK293 cells had no detectable levels of P2X1-3 and P2X6 under normal circumstances along with very low levels of P2X4 and P2X5 but when the cells were grown past confluence then all subtypes were expressed on the surface membrane with the exception of P2X2. The results are discussed in terms of the likely influence of ATP acting as an intercellular signaling molecule.

Expression and localisation of stanniocalcin 1 in rat bladder, kidney and ovary.

Bony fish use the glycoprotein hormone stanniocalcin (STC) to counteract hypercalcaemia. This is achieved through dual mechanisms involving gill calcium uptake inhibition and stimulation of renal inorganic phosphate reabsorption. Human STC (hSTC-1) shows considerable homology with both rat and mouse STC (mSTC) and their mRNA is expressed in a wide range of tissues. In fish, STC is produced by endocrine glands known as the corpuscles of Stannius but in mammals the widespread expression is suggestive of a paracrine rather than an endocrine role. In order to determine the distribution and strucutral characteristics of hSTC-1, the recombinant protein was expressed in bacteria, purified by metal-ion affinity chromatography, and a study was made of the likely epitopes for raising an antibody. This novel hSTC-1 antibody was used to test the purification protocol. Since the role of mammalian STC is largely unknown, the specific distribution of STC needed to be addressed. To test the specificity of the antibody, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)/Western blotting was undertaken in homogenised rat bladder, ovary and kidney.

Identification and localisation of ATP P2X receptors in rat midbrain.

P2X receptors that are gated by extracellular ATP are among the few known examples of ligand-gated cation-selective channels. There have been seven cloned proteins identified to date as members of the P2X receptor family in a wide range of tissues from the peripheral and central nervous systems and from many species. To determine the distribution of the P2X subtypes in the rat midbrain, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)/Western blotting was combined with immunolocalisation using confocal microscopy. Subtypes P2X1-6 were detected in the periaqueductal gray area and the ependymal layer bordering the ventricle with a widespread distribution.

Analysis of novel P2X subunit-specific antibodies in rat cardiac and smooth muscle.

P2X receptors are cation-selective channels gated by extracellular adenosine triphosphate (ATP). There are relatively few known types of ligand-gated receptors. In vertebrates they include acetylcholine (Ach), 5-hydroxytryptamine (5-HT), gamma-aminobutyric acid (GABA), glycine, and glutamate as well as ATP. Ach, 5-HT, GABA and glycine ligand-gated receptors are related in evolutionary terms, while glutamate and ATP receptors form separate groups. There have been seven cloned proteins identified to date as members of the P2X receptor family in a wide range of cells and species. We have carried out hydropathy investigations and sequence comparisons of each of the seven subunits in order to examine the putative transmembrane and cysteine-rich extracellular domains. Probable locations of disulphide bridges are consistent with there being two separate extracellular folding domains. Assessment of the putative surface-accessible regions was used to select small localised amino acid segments in nonglycosylated regions for raising antibodies against each of the P2X receptor subunits. To test the specificity of these novel P2X receptor antibodies and their presence in cardiac and smooth muscle, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)/Western blotting was undertaken in homogenised rat heart, bladder, kidney, and vas deferens.

Incisal edge reattachment: indications for use and clinical technique.

This article presents an overview of the evolution of the incisal edge reattachment procedure. Case reports are described of patients presenting with traumatised teeth in which the reattachment procedure was performed. A review is provided of present in vivo studies detailing long-term success rates in the clinical application of this procedure. Finally, a recommended technique for diagnosis and treatment is offered to improve success in this procedure which may benefit a significant segment of the paediatric and adolescent populations.

Incisal edge reattachment: the effect of preparation utilization and design.

OBJECTIVE: This study evaluated the effect of preparation utilization and design, and addition of resin composite to the bonding interface, on the fracture resistance of reattached incisal fragments. METHOD AND MATERIALS: Sixty bovine incisors were distributed among 1 control group and 5 experimental groups. Experimental specimens were sectioned 3.0 mm from the incisal edge with a 0.15-mm wafering blade at a 25-degree inclination apically in a faciolingual direction. Two groups received no further preparation. Specimens in the other 3 groups received either external bevels, internal bevels, or combined external and internal bevels. One preparationless group was reattached with dentin bonding agent alone. All other fragments were reattached with a dentin bonding agent-resin composite interface. After thermocycling and 4 weeks of bond weathering, specimens were sheared to failure in a universal testing machine. RESULTS: No significant differences in fracture strength were observed among any of the experimental groups, yet each displayed significantly less resistance to fracture than the control group. Reattachment of fragments in all groups restored approximately one half or one third the fracture strength of the control teeth for crown or root fractures, respectively. CONCLUSION: Compared to the simple, expedient regimen of using a dentin bonding agent alone, nonconservative tooth modification and the addition of resin composite to the bonding interface did not increase resistance to fracture and thus provided no retentive advantage.

Incisal edge reattachment: literature review and treatment perspectives.

Anterior crown fractures in children and adolescents are a common form of injury, affecting approximately 25% of that population. Common restorative treatments such as composite bonding, laminate veneers, or full-coverage restorations tend to sacrifice healthy tooth structure and challenge dentists to match the adjacent unrestored dentition. Incisal edge fragment reattachment, including the use of current bonding techniques, is a restorative treatment option that offers the advantages of simplicity, immediate esthetics, and conservatism in cases of dental trauma. This article presents a comprehensive literature review on this restorative technique. It also provides diagnostic and treatment algorithms to simplify and clarify the recommended diagnostic and clinical regimens.

Ligand recognition sites on P2X receptors studied by quantitative autoradiography of [3H]alpha,beta-methylene-ATP binding in rat brain.

The specificity of alpha, beta-methylene-ATP for P2X receptor binding sites in the CNS has been examined by testing the effects of several ATP analogues and other ATP-related substances on the binding of 10 nM [3H]alpha,beta-methylene-ATP to 20 microns thick sections of fresh-frozen rat brain. The labelling of the putative P2X receptor binding sites by [3H]alpha,beta-methylene-ATP was evaluated by quantitative densitometry. [3H]alpha,beta-methylene-ATP binding was strongly inhibited by two close ATP analogues, 3'-O-(trinitrophenyl)-adenosine-5'-triphosphate and beta,gamma-imido-ATP (IC50 2.5 microM). beta,gamma-Methylene-ATP was, however, less potent (< 50% inhibition at 25 microM). Inosine-5'-triphosphate, guanosine-5'-triphosphate, uridine-5'-triphosphate, and cytidine-5'-triphosphate were practically inactive up to concentrations of 100 microM. Periodate oxidised ATP and 1, N6-etheno-ATP produced < 50% inhibition at 100 and 500 microM concentrations, respectively. Cations (K+, Rb+, Cs+, and Mg2+ at 5 mM and Na+ at 150 mM) reduced [3H]alpha,beta-methylene-ATP binding by no more than 50%. Several agents known to interact with Ca2+- and/or ATP-related cationic channels (Cd2+, glibenclamide, dantrolene, nifedipine, and thapsigargin) had no effect. We conclude that [3H]alpha,beta-methylene-ATP at low nanomolar concentrations binds to a site that has very strict structural requirements and is pharmacologically similar to ATP P2X receptors.