1,568 research outputs found
The physiological significance of the water soluble components of nervous tissue
Part I. The mechanisms of acetylcholine synthesis1) Both citrate and acetate can act as acetyl
donors for choline acetylation by crude brain
extracts.2) In order to demonstrate the action of acetate
three conditions have to be observed: a) that
acetate is not added as a contaminant of the ATP:
b) that the enzymes bringing acetate into reaction
are protected during extraction from the acetone - dried powder by cysteine: c) that a ten times
higher level of coenzyme than for the citrate
system is used.á) Citrate acts as an acetyl donor by breaking
down to acetate and oxaloacetate. Mg, ATP and
the coenzyme are essential for this reaction.
The coenzyme requirement is low.4) Citrate can act in a similar manner in the
acetylation of sulphanilamide. Probably acetate
and oxaloacetate are not the only products of
citrate dismutation.5 The citrate and acetate "priming reactions"
carried out by the brain enzymes (in the absence
of choline) can be coupled with a liver fraction
(sulphanilamide condensing enzyme) to acetylate
sulphanilamide.6) At least two steps are involved in enzymic
acetylation. Activation of acetate (probably a coenzyme acetate complex) and condensation with
the acetyl acceptor are the main enzymic steps.7) "Choline acetylase" includes more than one
enzyme; it should only refer to the enzyme catalysing the condensation of active acetate with
choline.8) The validity of studies on the distribution of
"choline acetylase" in the nervous system is discussed. No change in the ability of various
parts of the system to synthesise acetylcholine is
expected since the "citrate enzyme" probably has a universal distribution.Part II:
The Purification and Structure of Coenzyme A.1) Evidence is presented to prove the identity of th
activator with the coenzyme of acetylation.2) The coenzyme is not responsible for the blue
fluorescence described by Comline (1948).3) A method of purification, based on the acidic
and reducing properties of the coenzyme is described.4) Acid hydrolysatevof the coenzyme contain a sulphur fragment which is probably identical with
the Lactobacillus bulgaricus factor.5) Digestion of the coenzyme with an enzyme derived from rabbit spleen releases two phosphoruscontaining fragments which can be resynthesised to
the coenzyme by a liver enzyme.6) Digestion of the coenzyme with a crude intestinal phosphatase releases three phosphorus-containing fragments which cannot be resynthesised
to the coenzyme under the conditions described.7) The structure of the coenzyme is discussed
Hospital Loneliness and the Patient-Physician Relationship: A Preliminary Analysis of Associations with Recovery in Bone Marrow Transplant Patients
The purpose of the present study was to examine general loneliness, hospital loneliness, and the patient-physician relationship in regards to their associations with Bone Marrow Transplant (BMT) recovery outcome variables (days until engraftment and quality of life). Fifteen (66.7% female, 33.3% male; 93.3% white, 6.7% Black/African American; average age 61.73) individuals who had an allogeneic or autologous BMT at The Mayo Clinic of Jacksonville completed the FACT-BMT, UCLA-Loneliness Scale Version 3, the CARE Measure, and provided disease and treatment information at the 6 month posttransplant date (+/- 30 days). Patients recovering from BMT indicated significantly higher scores of hospital loneliness in comparison to their general loneliness scores. This increase is believed to represent the outcome of experiencing hospital isolation during the post-transplant recovery process. Increases in hospital loneliness were marginally significant in predicting decreases in the patients overall quality of life. The patient physician consultational relationship was found to have a significant relationship with the number of days until engraftment, however the direction of the relationship was opposite the hypothesized direction. This may suggest that engraftment influences the quality of the relationship instead of vice versa. These results imply that there is a relationship between hospital isolation and increases in the amount of loneliness experienced during recovery from a BMT. Loneliness has been found to have a negative relationship with a number of physiological and quality of life outcomes. The present study also elucidates possible correlates with the patient-physician relationship
Star Formation triggered by cloud-cloud collisions
We present the results of SPH simulations in which two clouds, each having
mass and radius
, collide head-on at relative velocities of
. There is a clear trend with increasing . At low
, star formation starts later, and the shock-compressed
layer breaks up into an array of predominantly radial filaments; stars condense
out of these filaments and fall, together with residual gas, towards the centre
of the layer, to form a single large- cluster, which then evolves by
competitive accretion, producing one or two very massive protostars and a
diaspora of ejected (mainly low-mass) protostars; the pattern of filaments is
reminiscent of the hub and spokes systems identified recently by observers. At
high , star formation occurs sooner and the
shock-compressed layer breaks up into a network of filaments; the pattern of
filaments here is more like a spider's web, with several small- clusters
forming independently of one another, in cores at the intersections of
filaments, and since each core only spawns a small number of protostars, there
are fewer ejections of protostars. As the relative velocity is increased, the
{\it mean} protostellar mass increases, but the {\it maximum} protostellar mass
and the width of the mass function both decrease. We use a Minimal Spanning
Tree to analyse the spatial distributions of protostars formed at different
relative velocities.Comment: 10 pages, 11 figure
Range-separated density-functional theory with random phase approximation: detailed formalism and illustrative applications
Using Green-function many-body theory, we present the details of a formally
exact adiabatic-connection fluctuation-dissipation density-functional theory
based on range separation, which was sketched in Toulouse, Gerber, Jansen,
Savin and Angyan, Phys. Rev. Lett. 102, 096404 (2009). Range-separated
density-functional theory approaches combining short-range density functional
approximations with long-range random phase approximations (RPA) are then
obtained as well-identified approximations on the long-range Green-function
self-energy. Range-separated RPA-type schemes with or without long-range
Hartree-Fock exchange response kernel are assessed on rare-gas and
alkaline-earth dimers, and compared to range-separated second-order
perturbation theory and range-separated coupled-cluster theory.Comment: 15 pages, 3 figures, 2 table
Can females choose to avoid mating failure in the seed bug Lygaeus simulans?
We thank the Natural Environmental Research Council (Ph.D. studentship to E.V.G.) and the Association for the Study of Animal Behaviour (Undergraduate Project Scholarship awarded to V.L.B.) for funding.It is becoming increasingly clear that copulation does not necessarily always lead to offspring production in many organisms, despite fertilization success presumably being under both strong natural and sexual selection. In the seed bug Lygaeus simulans, between 40% and 60% of copulations fail to produce offspring, with this ‘mating failure’ representing a significantly repeatable male-associated trait. Mating has been demonstrated to be costly in this species and, as such, we might expect females to minimize the chance of mating failure by displaying a preference for males with higher insemination success where possible. After assaying males for mating failure, we asked whether females preferred males with a history of successful inseminations versus unsuccessful inseminations in pairwise mate choice trials. Contrary to our expectations, females showed no preference for more successful over less successful males. Moreover, females showed no preference for larger males in the choice trials, even though larger males were significantly more likely to successfully inseminate females in the initial assay. This apparent lack of female precopulatory choice suggests that postcopulatory choice mechanisms may be key to mating failure in this species. However, this does not necessarily explain why females pay the cost of mating with males they will then reject via postcopulatory processes. More generally, our results suggest that mating failure may play a largely underappreciated role in mating systems evolution, influencing both the cost of choosiness, and the costs and benefits of polyandry.Publisher PDFPeer reviewe
NOC Liverpool report for the Wirewalker underwater profiler deployment for the RidgeMix research programme
This report provides a review of a ‘wirewalker’ underwater profiler that was used for high resolution water quality and turbulence measurements as part of a mid-Atlantic ocean based scientific survey. The profiler utilised wave energy and buoyancy to generate automated, cyclic underwater vertical measurements. A drifting supporting surface buoy and mooring configuration was used that moved horizontally in response to underwater currents, surface wind and waves, while generating repeated sub-surface vertical scientific measurements.
The profiler instrumentation payload included a high-resolution chlorophyll-a fluorimeter, a fast sampling, precision conductivity, temperature and depth sensor (CTD) and a fragile, high resolution oceanic microstructure and turbulence sensor. A bespoke guard was used to help protect the fragile microstructure and turbulence sensors from damage. The mooring surface buoy instrumentation included telemetered GPS at nominally 30 minute intervals, a backup telemetered position indication, a VHF radio beacon based position locator and a solar powered night time light.
The experiment was designed to resolve time-variability of upper-ocean mixing and chlorophyll-a fluorescence over the Mid-Atlantic underwater Ridge, an internal wave generation hotspot. Typically more than three wave driven descents to 200 metres and subsequent buoyancy driven ascents to close to the sea surface were achieved per hour during a 22 day deployment, whilst continuously sampling. This represents the first time the UK National Oceanography Centre (NOC) have used this type of underwater profiling system for high resolution oceanic microstructure and turbulence measurements to support a scientific campaign.
Information to support a series of developing operational best practices for the use of this delicate and precision sensing arrangement with a wirewalker underwater profiler is provided. Recommendations relating to the future development of this versatile measurement system are also discussed
Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy
Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment
The Prosocial Framework: Theory, Practice and Applications Within Schools
Recent collaborations across psychological and evolutionary science have resulted in the emergence of an intervention programme for increasing the cohesion and effectiveness of human group processes. Prosocial (Atkins et al., 2019) combines Acceptance & Commitment Therapy (ACT; S. Hayes et al., 2012) and Multi-Level Selection Theory (Wilson & Sober, 1994) with Nobel Laureate Elinor Ostrom’s Core Design Principles (CDPs) for effective group-level processes (Ostrom, 2012, 2015). Ostrom’s work was ground-breaking but, being primarily descriptive in nature, did not provide a full account of the processes and procedures required to implement the CDPs. The current paper outlines the theoretical underpinnings of Prosocial and offers guidelines for its application within educational communities, providing specific examples of the wide array of ways in which the approach can be applied by professionals such as educational psychologists (EPs) to bring about positive change at the systemic level
Influence of Crohn’s disease related polymorphisms in innate immune function on ileal microbiome
We have previously identified NOD2 genotype and inflammatory bowel diseases (IBD) phenotype, as associated with shifts in the ileal microbiome (“dysbiosis”) in a patient cohort. Here we report an integrative analysis of an expanded number of Crohn's disease (CD) related genetic defects in innate immune function (NOD2, ATG16L1, IRGM, CARD9, XBP1, ORMDL3) and composition of the ileal microbiome by combining the initial patient cohort (Batch 1, 2005–2010, n = 165) with a second consecutive patient cohort (Batch 2, 2010–2012, n = 118). These combined patient cohorts were composed of three non-overlapping phenotypes: 1.) 106 ileal CD subjects undergoing initial ileocolic resection for diseased ileum, 2.) 88 IBD colitis subjects without ileal disease (predominantly ulcerative colitis but also Crohn’s colitis and indeterminate colitis, and 3.) 89 non-IBD subjects. Significant differences (FDR C. difficile infection, and NOD2 genotype on ileal dysbiosis in the expanded analysis. The relative abundance of the Proteobacteria phylum was positively associated with ileal CD and colitis phenotypes, but negatively associated with NOD2R genotype. Additional associations with ORMDL3 and XBP1 were detected at the phylum/subphylum level. IBD medications, such as immunomodulators and anti-TNFα agents, may have a beneficial effect on reversing dysbiosis associated with the IBD phenotype. Exploratory analysis comparing microbial composition of the disease unaffected region of the resected ileum between 27 ileal CD patients who subsequently developed endoscopic recurrence within 6–12 months versus 34 patients who did not, suggested that microbial biomarkers in the resected specimen helped stratify patients with respect to risk of post-surgical recurrence.</div
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