Blood Reservoir Function of the Fetal Guinea Pig Liver

To determine of the fetal liver functions as a blood reservoir, we measured liver blood volume under normal conditions and after hemorrhage and volume loading. Nineteen pregnant guinea pig sows and 54 near-term fetuses were injected intravenously with 51Cr-labeled red cells while the fetuses remained in utero. Ninety seconds later a 0.5-1.0 g sample of liver was garroted with a sharp wire into a tared tube with minimal blood loss. A blood sample was taken to measure counts per ml of blood, the fetus killed and the remainder of the liver weighed. Blood volume of the liver and body were calculated. Groups of fetuses were studied with normal volume, after 14% hemorrhage and 12% volume loading. Adult sows weighed 1235 ± 29 (SEM) g with a blood volume of 60.4 ± 2.3 ml, of which the liver contained 11.2 ± 0.5 ml. Fetuses weighed 58.2 ± 1.8 g. Under normal conditions fetal blood volume was 5.1 ± 0.2 ml and the liver contained 22.7 ± 1.8% of total blood volume. This fell to 16.9 ± 1.6% after hemorrhage, but did not change significantly from normal during volume loading. These results indicate the fetal liver is relatively larger than the adult and contains more blood per gram of tissue. Following decreases in blood volume the fetal liver acts as a blood reservoir by releasing blood into the circulation. It releases a volume equal to about 60% of the shed blood after a moderate hemorrhage

Distribution of Maternal and Fetal Blood Flow within Cotyledons of the Sheep Placenta

These studies explore the distribution of blood flow among small samples of placental tissue. Labeled microspheres (14 ± 1 pm) were Injected Into the left ventricle of six un-anesthetized ewes and Into the jugular vein of the fetus In utero. A total of 3,576 samples weighing 31. +11. (S.D.) mg were taken from seventeen cotyledons and counted for flow labels. Maternal and fetal flow within the cotyledons were both normally distributed with standard deviations of 44%. The maternal/ fetal flow ratio was less than 0.5 In 9% of the cotyledon, between 0.5 and 1.5 In 70%, and greater than 1.5 In 21%. Errors due to the method were estimated to contribute less than 10% of the flow variances. Maternal and fetal flows were significantly correlated (r = 0.57, p \u3c .001). Spatial flow patterns were visualized using computerized Image processing. The distribution of maternal and fetal flow may be a sensitive determinant of water transfer, and the distribution of their ratio explains about 50% of the uterine—umbilical venous oxygen tension gradient. Analysis of the correlation between samples vs. the distance separating them suggested a weight of roughly 125 mg for hypothetical placental regulatory units

Proteinase-activated receptor 2 modulates neuroinflammation in experimental autoimmune encephalomyelitis and multiple sclerosis

The proteinase-activated receptors (PARs) are widely recognized for their modulatory properties of inflammation and neurodegeneration. We investigated the role of PAR2 in the pathogenesis of multiple sclerosis (MS) in humans and experimental autoimmune encephalomyelitis (EAE) in mice. PAR2 expression was increased on astrocytes and infiltrating macrophages in human MS and murine EAE central nervous system (CNS) white matter (P < 0.05). Macrophages and astrocytes from PAR2 wild-type (WT) and knockout (KO) mice exhibited differential immune gene expression with PAR2 KO macrophages showing significantly higher interleukin 10 production after lipopolysaccharide stimulation (P < 0.001). PAR2 activation in macrophages resulted in the release of soluble oligodendrocyte cytotoxins (P < 0.01). Myelin oligodendrocyte glycoprotein–induced EAE caused more severe inflammatory gene expression in the CNS of PAR2 WT animals (P < 0.05), together with enhanced T cell proliferation and interferon γ production (P < 0.05), compared with KO littermates. Indeed, PAR2 WT animals showed markedly greater microglial activation and T lymphocyte infiltration accompanied by worsened demyelination and axonal injury in the CNS compared with their PAR2 KO littermates. Enhanced neuropathological changes were associated with a more severe progressive relapsing disease phenotype (P < 0.001) in WT animals. These findings reveal previously unreported pathogenic interactions between CNS PAR2 expression and neuroinflammation with ensuing demyelination and axonal injury

Giving something back? Sentiments of privilege and social responsibility among elite graduates from Britain and France

This article explores the complex relationship between transnational elites and civil society through examining the contrasting orientations of two cohorts of ‘elite graduates’ from Paris and Oxford. Both cohorts believe their privileged status has been earned through hard work and ability. But they are also aware that they have benefited from advantages not available to all. Perhaps because of this, they express the need to ‘give something back’. However, the means through which they seek to discharge their social responsibilities are very different. While the Oxford graduates seek to ‘give something back’ through volunteering and third sector engagement, the Paris graduates will ‘give something back’ through public service. The article discusses how the contrasting relationship between the state, civil society and the education system in these two countries may shape dispositions, and speculates on the extent to which these elite recruits’ commitment to ‘give something back’ will make a difference

The Compiler Forest

Abstract. We address the problem of writing compilers targeting complex execution environments, such as computer clusters composed of machines with multi-core CPUs. To that end we introduce partial compilers. These compilers can pass sub-programs to several child (partial) compilers, combining the code generated by their children to generate the final target code. We define a set of high-level polymorphic operations manipulating both compilers and partial compilers as first-class values. These mechanisms provide a software architecture for modular compiler construction. This allows the building of a forest of compilers, providing a structured treatment of multistage compilers.

The Dynamics of Functional Brain Networks:Integrated Network States during Cognitive Task Performance

Higher brain function relies upon the ability to flexibly integrate information across specialized communities of brain regions, however it is unclear how this mechanism manifests over time. In this study, we use time-resolved network analysis of functional magnetic resonance imaging data to demonstrate that the human brain traverses between two functional states that maximize either segregation into tight-knit communities or integration across otherwise disparate neural regions. The integrated state enables faster and more accurate performance on a cognitive task, and is associated with dilations in pupil diameter, suggesting that ascending neuromodulatory systems may govern the transition between these alternative modes of brain function. Our data confirm a direct link between cognitive performance and the dynamic reorganization of the network structure of the brain.Comment: 38 pages, 4 figure

Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, Canada

Background: This study provides experimental evidence for biologically induced precipitation of magnesium carbonates, specifically dypingite (Mg(CO)(OH) ·5HO), by cyanobacteria from an alkaline wetland near Atlin, British Columbia. This wetland is part of a larger hydromagnesite (Mg(CO)(OH) ·4HO) playa. Abiotic and biotic processes for magnesium carbonate precipitation in this environment are compared. Results: Field observations show that evaporation of wetland water produces carbonate films of nesquehonite (MgCO ·3HO) on the water surface and crusts on exposed surfaces. In contrast, benthic microbial mats possessing filamentous cyanobacteria (Lyngbya sp.) contain platy dypingite (Mg (CO)4(OH)·5HO) and aragonite. Bulk carbonates in the benthic mats (δC avg. = 6.7%, δO avg. = 17.2%) were isotopically distinguishable from abiotically formed nesquehonite (δC avg. = 9.3%, δO avg. = 24.9%). Field and laboratory experiments, which emulated natural conditions, were conducted to provide insight into the processes for magnesium carbonate precipitation in this environment. Field microcosm experiments included an abiotic control and two microbial systems, one containing ambient wetland water and one amended with nutrients to simulate eutrophic conditions. The abiotic control developed an extensive crust of nesquehonite on its bottom surface during which [Mg] decreased by 16.7% relative to the starting concentration. In the microbial systems, precipitation occurred within the mats and was not simply due to the capturing of mineral grains settling out of the water column. Magnesium concentrations decreased by 22.2% and 38.7% in the microbial systems, respectively. Laboratory experiments using natural waters from the Atlin site produced rosettes and flakey globular aggregates of dypingite precipitated in association with filamentous cyanobacteria dominated biofilms cultured from the site, whereas the abiotic control again precipitated nesquehonite. Conclusion: Microbial mats in the Atlin wetland create ideal conditions for biologically induced precipitation of dypingite and have presumably played a significant role in the development of this natural Mg-carbonate playa. This biogeochemical process represents an important link between the biosphere and the inorganic carbon pool

A verification framework for interannual-to-decadal predictions experiments

Decadal predictions have a high profile in the climate science community and beyond, yet very little is known about their skill. Nor is there any agreed protocol for estimating their skill. This paper proposes a sound and coordinated framework for verification of decadal hindcast experiments. The framework is illustrated for decadal hindcasts tailored to meet the requirements and specifications of CMIP5 (Coupled Model Intercomparison Project phase 5). The chosen metrics address key questions about the information content in initialized decadal hindcasts. These questions are: (1) Do the initial conditions in the hindcasts lead to more accurate predictions of the climate, compared to un-initialized climate change projections? and (2) Is the prediction model’s ensemble spread an appropriate representation of forecast uncertainty on average? The first question is addressed through deterministic metrics that compare the initialized and uninitialized hindcasts. The second question is addressed through a probabilistic metric applied to the initialized hindcasts and comparing different ways to ascribe forecast uncertainty. Verification is advocated at smoothed regional scales that can illuminate broad areas of predictability, as well as at the grid scale, since many users of the decadal prediction experiments who feed the climate data into applications or decision models will use the data at grid scale, or downscale it to even higher resolution. An overall statement on skill of CMIP5 decadal hindcasts is not the aim of this paper. The results presented are only illustrative of the framework, which would enable such studies. However, broad conclusions that are beginning to emerge from the CMIP5 results include (1) Most predictability at the interannual-to-decadal scale, relative to climatological averages, comes from external forcing, particularly for temperature; (2) though moderate, additional skill is added by the initial conditions over what is imparted by external forcing alone; however, the impact of initialization may result in overall worse predictions in some regions than provided by uninitialized climate change projections; (3) limited hindcast records and the dearth of climate-quality observational data impede our ability to quantify expected skill as well as model biases; and (4) as is common to seasonal-to-interannual model predictions, the spread of the ensemble members is not necessarily a good representation of forecast uncertainty. The authors recommend that this framework be adopted to serve as a starting point to compare prediction quality across prediction systems. The framework can provide a baseline against which future improvements can be quantified. The framework also provides guidance on the use of these model predictions, which differ in fundamental ways from the climate change projections that much of the community has become familiar with, including adjustment of mean and conditional biases, and consideration of how to best approach forecast uncertainty

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Patterns of smoking behavior among physicians in Yerevan, Armenia

BACKGROUND: Physicians can play an important role in smoking prevention and control. This study will identify smoking prevalence among physicians in Yerevan, Armenia. It will also explore how the smoking behaviors of physicians, their perceived ability to influence patient smoking behavior, and their knowledge about health outcomes related to smoking influence their interaction with patients. METHODS: A cross-sectional, self-administered, anonymous survey was conducted in July, 2004, among 12 healthcare facilities in Yerevan. Analyses are based on responses from 240 physicians, representing a 70% response rate. RESULTS: The percentage of current smokers was significantly higher in men than women (48.5% vs. 12.8% regular and 6.8% vs. 4.5% occasional). Among current smokers, 52.7% of men compared with 13.0% of women had previously smoked in the presence of patients. Only 35.3% felt well prepared to assist patients to quit smoking. Physicians who smoke are less likely to ask their patients about their smoking behavior or believe their example is likely to influence their patients. Level of perceived preparedness to assist patients to quit smoking was positively associated with knowledge about known health risks associated with smoking. CONCLUSION: Smoking prevalence is high among physicians in the 12 healthcare facilities in Yerevan, and a large percentage of physician smoke in the presence of their patients. Physician smoking behavior and knowledge of smoking related health outcomes in Yerevan influences whether they counsel patients regarding smoking