4,202 research outputs found
Application of the optimized carbon monoxide rebreathing method for the measurement of total haemoglobin mass in chronic liver disease
Background:
Anemia is common in liver cirrhosis. This generally infers a fall in total hemoglobin mass (tHbâmass). However, hemoglobin concentration ([Hb]) may fall due to an expansion in plasma volume (PV). The âoptimized carbon monoxide rebreathing methodâ (oCOR) measures tHbâmass directly and PV (indirectly using hematocrit). It relies upon carboxyhemoglobin (COHb) distribution throughout the entire circulation. In healthy subjects, such distribution is complete within 6â8 min. Given the altered circulatory dynamics in cirrhosis, we sought in this pilot study, to assess whether this was true in cirrhosis. The primary aim was to ascertain if the standard timings for the oCOR were applicable to patients with chronic liver disease and cirrhosis. The secondary aim was to explore the applicability of standard CO dosing methodologies to this patient population.
Methods:
Sixteen patients with chronic liver parenchymal disease were studied. However, tHbâmass was determined using the standard oCOR technique before elective paracentesis. Three subjects had an inadequate COHb% rise. In the remaining 13 (11 male), mean ± standard deviation (SD ) age was 52 ± 13.8 years, body mass 79.1 ± 11.4 kg, height 175 ± 6.8 cm. To these, mean ± SD dose of carbon monoxide (CO) gas administered was 0.73 ± 0.13 ml/kg COHb values at baseline, 6 and 8 min (and â7âmin valueâ) were compared to those at 10, 12, 15 and 20 min after CO rebreathing.
Results:
The â7âmin valueâ for median COHb% (IQR) of 6.30% (6.21%â7.47%) did not differ significantly from those at subsequent time points (8 min: 6.30% (6.21%â7.47%), 10 min: 6.33% (6.00%â7.50%), 12 min: 6.33% (5.90%â7.40%), 15 min: 6.37% (5.80%â7.33%), 20 min: 6.27% (5.70%â7.20%)). Mean difference in calculated tHbâmass between minute 7 and minute 20 was only 4.1 g, or 0.6%, p = .68. No subjects reported any adverse effects.
Conclusions:
The oCOR method can be safely used to measure tHbâmass in patients with chronic liver disease and ascites, without adjustment of blood sample timings. Further work might refine and validate appropriate dosing regimens
Electromagnetic Form Factors of the Nucleon and Compton Scattering
We review the experimental and theoretical status of elastic electron
scattering and elastic low-energy photon scattering (with both real and virtual
photons) from the nucleon. As a consequence of new experimental facilities and
new theoretical insights, these subjects are advancing with unprecedented
precision. These reactions provide many important insights into the spatial
distributions and correlations of quarks in the nucleon.Comment: 47 pages, 18 figures, includes corrections and updates to published
manuscrip
Time-dependent response of a zonally averaged oceanâatmosphereâsea ice model to Milankovitch forcing
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer-Verlag for personal use, not for redistribution. The definitive version was published in Climate Dynamics 6 (2010): 763-779, doi:10.1007/s00382-010-0790-6.An ocean-atmosphere-sea ice model is developed to explore the time-dependent
response of climate to Milankovitch forcing for the time interval 5-3 Myr BP. The ocean
component is a zonally averaged model of the circulation in five basins (Arctic, Atlantic,
Indian, Pacific, and Southern Oceans). The atmospheric component is a one-dimensional
(latitudinal) energy balance model, and the sea-ice component is a thermodynamic model.
Two numerical experiments are conducted. The first experiment does not include sea ice
and the Arctic Ocean; the second experiment does. Results from the two experiments are
used to investigate (i) the response of annual mean surface air and ocean temperatures to
Milankovitch forcing, and (ii) the role of sea ice in this response.
In both experiments, the response of air temperature is dominated by obliquity cycles
at most latitudes. On the other hand, the response of ocean temperature varies with latitude
and depth. Deep water formed between 45°N-65°N in the Atlantic Ocean mainly responds
to precession. In contrast, deep water formed south of 60°S responds to obliquity when sea
ice is not included. Sea ice acts as a time-integrator of summer insolation changes such that
annual mean sea-ice conditions mainly respond to obliquity. Thus, in the presence of sea
ice, air temperature changes over the sea ice are amplified, and temperature changes in deep
water of southern origin are suppressed since water below sea ice is kept near the freezing
point.This work was supported by an NSERC Discovery
Grant awarded to L.A.M. We also thank GEC3 for a Network Grant
Demonstration of infectious salmon anaemia virus (ISAV) endocytosis in erythrocytes of Atlantic salmon
Infectious salmon anaemia (ISA) virus (ISAV) is a fish orthomyxovirus that has recently been assigned to the new genus Isavirus within the family Orthomyxoviridae. It possesses the major functional characteristics of the virus family including haemagglutinating, receptor destroying enzyme (RDE), and fusion activities associated with the virion surface proteins. It is generally accepted that ISAV agglutinates erythrocytes of several fish species and that the ISAV RDE activity dissolves this haemagglutination reaction except for Atlantic salmon (Salmo salar) erythrocytes. We used electron microscopy to examine the physical interaction between ISAV and erythrocytes from Atlantic salmon and rainbow trout (Oncorhynchus mykiss) during haemagglutination. We present evidence that ISAV enters into Atlantic salmon erythrocytes. Atlantic salmon erythrocytes incubated with ISAV for 4 hours showed endocytosis of the virus particles, which is consistent with virus infection. These observations suggest that the lack of dissolution of ISAV-induced haemagglutination of Atlantic salmon erythrocytes favours virus infection of the erythrocytes. Moreover, such a haemagglutination-infection phenotype is fundamentally different from haemagglutination by avian and mammalian orthomyxoviruses, and is indicative of a different pathogenesis for the fish orthomyxovirus
Local science and media engagement on climate change
Climate scientists can do a better job of communicating their work to local communities and reignite interest in the issue. Local media outlets provide a unique opportunity to build a platform for scientists to tell their stories and engage in a dialogue with people currently outside the 'climate bubble'
Neuroinflammation and Neuronal Loss Precede AÎČ Plaque Deposition in the hAPP-J20 Mouse Model of Alzheimer's Disease
Recent human trials of treatments for Alzheimer's disease (AD) have been largely unsuccessful, raising the idea that treatment may need to be started earlier in the disease, well before cognitive symptoms appear. An early marker of AD pathology is therefore needed and it is debated as to whether amyloid-ÎČAÎČ? plaque load may serve this purpose. We investigated this in the hAPP-J20 AD mouse model by studying disease pathology at 6, 12, 24 and 36 weeks. Using robust stereological methods, we found there is no neuron loss in the hippocampal CA3 region at any age. However loss of neurons from the hippocampal CA1 region begins as early as 12 weeks of age. The extent of neuron loss increases with age, correlating with the number of activated microglia. Gliosis was also present, but plateaued during aging. Increased hyperactivity and spatial memory deficits occurred at 16 and 24 weeks. Meanwhile, the appearance of plaques and oligomeric AÎČ were essentially the last pathological changes, with significant changes only observed at 36 weeks of age. This is surprising given that the hAPP-J20 AD mouse model is engineered to over-expresses AÎČ. Our data raises the possibility that plaque load may not be the best marker for early AD and suggests that activated microglia could be a valuable marker to track disease progression. © 2013 Wright et al
PCV13 induced IgG responses in serum associate with serotype-specific IgG in the lung
Pneumococcal conjugate vaccine efficacy is lower for non-invasive pneumonia than invasive disease. In this study, participants were vaccinated with PCV13 or HepA (control). Bronchoalveolar lavage samples were taken between 2-6 months and serum at 4- and 7-weeks post vaccination. In the lung, anti-capsular IgG levels were higher in the PCV13 group compared to control for all serotypes, except 3 and 6B. Systemically, IgG levels were elevated in the PCV group at 4-weeks for all serotypes, except 3. IgG in BAL and serum positively correlated for nearly all serotypes. PCV13 shows poor immunogenicity to serotype 3, implying lack of protective efficacy.
Clinical trial registration with ISRCTN: 4534043
Neo-Aristotelian Naturalism and the Evolutionary Objection: Rethinking the Relevance of Empirical Science
Neo-Aristotelian metaethical naturalism is a modern attempt at naturalizing ethics using ideas from Aristotleâs teleological metaphysics. Proponents of this view argue that moral virtue in human beings is an instance of natural goodness, a kind of goodness supposedly also found in the realm of non-human living things. Many critics question whether neo-Aristotelian naturalism is tenable in light of modern evolutionary biology. Two influential lines of objection have appealed to an evolutionary understanding of human nature and natural teleology to argue against this view. In this paper, I offer a reconstruction of these two seemingly different lines of objection as raising instances of the same dilemma, giving neo-Aristotelians a choice between contradicting our considered moral judgment and abandoning metaethical naturalism. I argue that resolving the dilemma requires showing a particular kind of continuity between the norms of moral virtue and norms that are necessary for understanding non-human living things. I also argue that in order to show such a continuity, neo-Aristotelians need to revise the relationship they adopt with empirical science and acknowledge that the latter is relevant to assessing their central commitments regarding living things. Finally, I argue that to move this debate forward, both neo-Aristotelians and their critics should pay attention to recent work on the concept of organism in evolutionary and developmental biology
Could Public Restrooms Be an Environment for Bacterial Resistomes?
PMCID: PMC3547874This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Internal construct validity of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS): a Rasch analysis using data from the Scottish Health Education Population Survey
Background: The Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) was developed to meet demand for instruments
to measure mental well-being. It comprises 14 positively phrased Likert-style items and fulfils classic criteria for scale development. We report here the internal construct validity of WEMWBS from the perspective of the Rasch measurement model.
Methods: The model was applied to data collected from 779 respondents in Wave 12 (Autumn 2006) of the Scottish Health
Education Population Survey. Respondents were aged 16â74 (average 41.9) yrs.
Results: Initial fit to model expectations was poor. The items 'I've been feeling good about myself', 'I've been interested in new things' and 'I've been feeling cheerful' all showed significant misfit to model expectations, and were deleted. This led to a marginal improvement in fit to the model. After further analysis, more items were deleted and a strict unidimensional seven item scale (the Short Warwick Edinburgh Mental Well-Being Scale (SWEMWBS)) was resolved. Many items deleted because of misfit with
model expectations showed considerable bias for gender. Two retained items also demonstrated bias for gender but, at the
scale level, cancelled out. One further retained item 'I've been feeling optimistic about the future' showed bias for age. The correlation between the 14 item and 7 item versions was 0.954. Given fit to the Rasch model, and strict unidimensionality, SWEMWBS provides an interval scale estimate of mental well-being.
Conclusion: A short 7 item version of WEMWBS was found to satisfy the strict unidimensionality expectations of the Rasch model, and be largely free of bias. This scale, SWEMWBS, provides a raw score-interval scale transformation for use in parametric procedures. In terms of face validity, SWEMWBS presents a more restricted view of mental well-being than the 14 item WEMWBS, with most items representing aspects of psychological and eudemonic well-being, and few covering hedonic well-being or affect. However, robust measurement properties combined with brevity make SWEMWBS preferable to WEMWBS at present for monitoring mental well-being in populations. Where face validity is an issue there remain arguments for continuing to collect data on the full 14 item WEMWBS
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