3,138 research outputs found
Recent changes in area and thickness of Torngat Mountain glaciers (northern Labrador, Canada)
The Torngat Mountains National Park, northern Labrador, Canada, contains more
than 120 small glaciers: the only remaining glaciers in continental northeast
North America. These small cirque glaciers exist in a unique topo-climatic
setting, experiencing temperate maritime summer conditions yet very cold and
dry winters, and may provide insights into the deglaciation dynamics of
similar small glaciers in temperate mountain settings. Due to their size and
remote location, very little information exists regarding the health of these
glaciers. Just a single study has been published on the contemporary
glaciology of the Torngat Mountains, focusing on net mass balances from 1981
to 1984. This paper addresses the extent to which glaciologically relevant
climate variables have changed in northern Labrador in concert with
20th-century Arctic warming, and how these changes have affected Torngat Mountain
glaciers. Field surveys and remote-sensing analyses were used to measure
regional glacier area loss of 27âŻ% from 1950 to 2005, substantial rates of
ice surface thinning (up to 6âŻmâŻyr<sup>â1</sup>) and volume losses at Abraham,
Hidden, and Minaret glaciers, between 2005 and 2011. Glacier mass balances
appear to be controlled by variations in winter precipitation and,
increasingly, by strong summer and autumn atmospheric warming since the
early 1990s, though further observations are required to fully understand
mass balance sensitivities. This study provides the first comprehensive
contemporary assessment of Labrador glaciers and will inform both regional
impact assessments and syntheses of global glacier mass balance
Role of vascular smooth muscle cell clonality in atherosclerosis
Atherosclerotic cardiovascular disease remains the leading cause of death worldwide. While many cell types contribute to the growing atherosclerotic plaque, the vascular smooth muscle cell (SMC) is a major contributor due in part to its remarkable plasticity and ability to undergo phenotype switching in response to injury. SMCs can migrate into the fibrous cap, presumably stabilizing the plaque, or accumulate within the lesional core, possibly accelerating vascular inflammation. How SMCs expand and react to disease stimuli has been a controversial topic for many decades. While early studies relying on X-chromosome inactivation were inconclusive due to low resolution and sensitivity, recent advances in multi-color lineage tracing models have revitalized the concept that SMCs likely expand in an oligoclonal fashion during atherogenesis. Current efforts are focused on determining whether all SMCs have equal capacity for clonal expansion or if a âstem-likeâ progenitor cell may exist, and to understand how constituents of the clone decide which phenotype they will ultimately adopt as the disease progresses. Mechanistic studies are also beginning to dissect the processes which confer cells with their overall survival advantage, test whether these properties are attributable to intrinsic features of the expanding clone, and define the role of cross-talk between proliferating SMCs and other plaque constituents such as neighboring macrophages. In this review, we aim to summarize the historical perspectives on SMC clonality, highlight unanswered questions, and identify translational issues which may need to be considered as therapeutics directed against SMC clonality are developed as a novel approach to targeting atherosclerosis
Cosmic-ray-induced ionization in molecular clouds adjacent to supernova remnants - Tracing the hadronic origin of GeV gamma radiation
Energetic gamma rays (GeV to TeV photon energy) have been detected toward
several supernova remnants (SNR) associated with molecular clouds. If the gamma
rays are produced mainly by hadronic processes rather than leptonic processes
like bremsstrahlung, then the flux of energetic cosmic ray (CR) nuclei (>1 GeV)
required to produce the gamma rays can be inferred at the site where the
particles are accelerated in SNR shocks. It is of great interest to understand
the acceleration of the CR of lower energy (<1 GeV) accompanying the energetic
component. These particles of lower energy are most effective in ionizing
interstellar gas, leaving an observable imprint on the interstellar ion
chemistry. A correlation of energetic gamma radiation with enhanced
interstellar ionization can thus support the hadronic origin of the gamma rays
and constrain the acceleration of ionizing CR in SNR. We propose a method to
test the hadronic origin of GeV gamma rays from SNR associated with a molecular
cloud. We use observational gamma ray data for each of these SNR known,
modeling the observations to obtain the underlying proton spectrum assuming
that the gamma rays are produced by pion decay. Assuming that the acceleration
mechanism does not only produce high energy protons, but also low energy
protons, this proton spectrum at the source is then used to calculate the
ionization rate of the molecular cloud. Ionized molecular hydrogen triggers a
chemical network forming molecular ions. The relaxation of these ions results
in characteristic line emission, which can be predicted. We show that the
ionization rate for at least two objects is more than an order of magnitude
above Galactic average for molecular clouds, hinting at an enhanced formation
rate of molecular ions. There will be interesting opportunities to measure
crucial molecular ions in the infrared and submillimeter-wave parts of the
spectrum.Comment: published in Astronomy and Astrophysics, 13 pages, 19 figure
Closed circuit rebreathing to achieve inert gas wash-in for multiple breath wash-out
Multiple breath wash-out (MBW) testing requires prior wash-in of inert tracer gas. Wash-in efficiency can be enhanced by a rebreathing tracer in a closed circuit. Previous attempts to deploy this did not account for the impact of CO2Â accumulation on patients and were unsuccessful. We hypothesised that an effective rebreathe wash-in could be delivered and it would not alter wash-out parameters.
Computer modelling was used to assess the impact of the rebreathe method on wash-in efficiency. Clinical testing of open and closed circuit wash-inâwash-out was performed in healthy controls and adult patients with cystic fibrosis (CF) using a circuit with an effective CO2Â scrubber and a refined wash-in protocol.
Wash-in efficiency was enhanced by rebreathing. There was no difference in mean lung clearance index between the two wash-in methods for controls (6.5 versus 6.4; p=0.2, n=12) or patients with CF (10.9 versus 10.8; p=0.2, n=19). Test time was reduced by rebreathe wash-in (156 versus230â
s for CF patients, p<0.001) and both methods were well tolerated. End wash-in CO2Â was maintained below 2% in most cases.
Rebreatheâwash-in is a promising development that, when correctly deployed, reduces wash-in time and facilitates portable MBW testing. For mild CF, wash-out outcomes are equivalent to an open circuit
Kidney replacement therapy: trends in incidence, treatment, and outcomes of myocardial infarction and stroke in a nationwide Scottish study
BACKGROUND AND AIMS: Patients with kidney failure have a higher risk of cardiovascular disease compared with the general population. Whilst temporal trends of myocardial infarction and stroke are declining in the general population, these have not been evaluated in patients with kidney failure. This study aimed to describe national trends in the incidence, treatment, and outcomes of myocardial infarction and stroke in patients with kidney failure (i.e. on dialysis or with a kidney transplant) over a 20-year period, stratified by age and sex.METHODS: In this retrospective national data linkage study, all patients with kidney failure in Scotland (UK) receiving kidney replacement therapy between January 1996 and December 2016 were linked to national hospitalization, prescribing, and death records. The primary outcomes were the incidence of myocardial infarction and stroke, and subsequent cardiovascular death. Generalized additive models were constructed to estimate age-standardized, sex-stratified incidence rates and trends in cardiovascular and all-cause death.RESULTS: Amongst 16 050 patients with kidney failure [52 (SD 15) years; 41.5% women], there were 1992 [66 (SD 12) years; 34.8% women] and 996 [65 (SD 13) years; 45.1% women] incident myocardial infarctions and strokes, respectively, between January 1996 and December 2016. During this period, the age-standardized incidence of myocardial infarction per 100 000 decreased in men {from 4376 [95% confidence interval (CI) 3998-4785] to 1835 (95% CI 1692-1988)} and women [from 3268 (95% CI 2982-3593) to 1369 (95% CI 1257-1491)]. Similarly, the age-standardized incidence of stroke per 100 000 also decreased in men [from 1978 (95% CI 1795-2175) to 799 (95% CI 729-875)] and women [from 2234 (95% CI 2031-2468) to 903 (95% CI 824-990)]. Compared with the general population, the incidence of myocardial infarction was four- to eight-fold higher in patients with kidney failure, whilst for stroke it was two- to four-fold higher. The use of evidence-based cardioprotective treatment increased over the study period, and the predicted probability of cardiovascular death within 1 year of myocardial infarction for a 66-year-old patient with kidney failure (mean age of the cohort) fell in men (76.6% to 38.6%) and women (76.8% to 38.8%), and also decreased in both sexes following stroke (men, from 63.5% to 41.4%; women, from 67.6% to 45.8%).CONCLUSIONS: The incidence of myocardial infarction and stroke has halved in patients with kidney failure over the past 20 years but remains significantly higher than in the general population. Despite improvements in treatment and outcomes, the prognosis of these patients following myocardial infarction and stroke remains poor.</p
Kidney replacement therapy:trends in incidence, treatment, and outcomes of myocardial infarction and stroke in a nationwide Scottish study
BACKGROUND AND AIMS: Patients with kidney failure have a higher risk of cardiovascular disease compared with the general population. Whilst temporal trends of myocardial infarction and stroke are declining in the general population, these have not been evaluated in patients with kidney failure. This study aimed to describe national trends in the incidence, treatment, and outcomes of myocardial infarction and stroke in patients with kidney failure (i.e. on dialysis or with a kidney transplant) over a 20-year period, stratified by age and sex.METHODS: In this retrospective national data linkage study, all patients with kidney failure in Scotland (UK) receiving kidney replacement therapy between January 1996 and December 2016 were linked to national hospitalization, prescribing, and death records. The primary outcomes were the incidence of myocardial infarction and stroke, and subsequent cardiovascular death. Generalized additive models were constructed to estimate age-standardized, sex-stratified incidence rates and trends in cardiovascular and all-cause death. RESULTS: Amongst 16 050 patients with kidney failure [52 (SD 15) years; 41.5% women], there were 1992 [66 (SD 12) years; 34.8% women] and 996 [65 (SD 13) years; 45.1% women] incident myocardial infarctions and strokes, respectively, between January 1996 and December 2016. During this period, the age-standardized incidence of myocardial infarction per 100 000 decreased in men {from 4376 [95% confidence interval (CI) 3998â4785] to 1835 (95% CI 1692â1988)} and women [from 3268 (95% CI 2982â3593) to 1369 (95% CI 1257â1491)]. Similarly, the age-standardized incidence of stroke per 100 000 also decreased in men [from 1978 (95% CI 1795â2175) to 799 (95% CI 729â875)] and women [from 2234 (95% CI 2031â2468) to 903 (95% CI 824â990)]. Compared with the general population, the incidence of myocardial infarction was four- to eight-fold higher in patients with kidney failure, whilst for stroke it was two- to four-fold higher. The use of evidence-based cardioprotective treatment increased over the study period, and the predicted probability of cardiovascular death within 1 year of myocardial infarction for a 66-year-old patient with kidney failure (mean age of the cohort) fell in men (76.6% to 38.6%) and women (76.8% to 38.8%), and also decreased in both sexes following stroke (men, from 63.5% to 41.4%; women, from 67.6% to 45.8%). CONCLUSIONS: The incidence of myocardial infarction and stroke has halved in patients with kidney failure over the past 20 years but remains significantly higher than in the general population. Despite improvements in treatment and outcomes, the prognosis of these patients following myocardial infarction and stroke remains poor
Kidney replacement therapy:trends in incidence, treatment, and outcomes of myocardial infarction and stroke in a nationwide Scottish study
BACKGROUND AND AIMS: Patients with kidney failure have a higher risk of cardiovascular disease compared with the general population. Whilst temporal trends of myocardial infarction and stroke are declining in the general population, these have not been evaluated in patients with kidney failure. This study aimed to describe national trends in the incidence, treatment, and outcomes of myocardial infarction and stroke in patients with kidney failure (i.e. on dialysis or with a kidney transplant) over a 20-year period, stratified by age and sex.METHODS: In this retrospective national data linkage study, all patients with kidney failure in Scotland (UK) receiving kidney replacement therapy between January 1996 and December 2016 were linked to national hospitalization, prescribing, and death records. The primary outcomes were the incidence of myocardial infarction and stroke, and subsequent cardiovascular death. Generalized additive models were constructed to estimate age-standardized, sex-stratified incidence rates and trends in cardiovascular and all-cause death. RESULTS: Amongst 16 050 patients with kidney failure [52 (SD 15) years; 41.5% women], there were 1992 [66 (SD 12) years; 34.8% women] and 996 [65 (SD 13) years; 45.1% women] incident myocardial infarctions and strokes, respectively, between January 1996 and December 2016. During this period, the age-standardized incidence of myocardial infarction per 100 000 decreased in men {from 4376 [95% confidence interval (CI) 3998â4785] to 1835 (95% CI 1692â1988)} and women [from 3268 (95% CI 2982â3593) to 1369 (95% CI 1257â1491)]. Similarly, the age-standardized incidence of stroke per 100 000 also decreased in men [from 1978 (95% CI 1795â2175) to 799 (95% CI 729â875)] and women [from 2234 (95% CI 2031â2468) to 903 (95% CI 824â990)]. Compared with the general population, the incidence of myocardial infarction was four- to eight-fold higher in patients with kidney failure, whilst for stroke it was two- to four-fold higher. The use of evidence-based cardioprotective treatment increased over the study period, and the predicted probability of cardiovascular death within 1 year of myocardial infarction for a 66-year-old patient with kidney failure (mean age of the cohort) fell in men (76.6% to 38.6%) and women (76.8% to 38.8%), and also decreased in both sexes following stroke (men, from 63.5% to 41.4%; women, from 67.6% to 45.8%). CONCLUSIONS: The incidence of myocardial infarction and stroke has halved in patients with kidney failure over the past 20 years but remains significantly higher than in the general population. Despite improvements in treatment and outcomes, the prognosis of these patients following myocardial infarction and stroke remains poor
Declaring a Patient Brain Dead on Extracorporeal Membrane Oxygenation (ECMO): Are There Guidelines or Misconceptions
Objectives: To review the clinical practice variations and trends with declaring patients brain dead on ECMO To highlight the need for the development of consensus guidelines to assist clinicians in the accurate diagnosis of brain death in this specific patient populatio
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