5,558 research outputs found
Exacerbation of erythropoietic protoporphyria by hyperthyroidism
Erythropoietic protoporphyria (EPP) is a hereditary disorder caused by deficiency of ferrochelatase, the last enzyme in the heme biosynthetic pathway. The majority of EPP patients present with a clinical symptom of painful phototoxicity. Liver damage, the most serious complication of EPP, occurs in <5% of the patients. This report describes a case of an EPP patient who complained of worsening cutaneous symptoms, nervousness, and insomnia. Laboratory tests showed highly increased protoporphyrin concentration in erythrocytes and elevated serum transaminases that are indicative of EPP-related liver damage. The subsequent finding of decreased serum thyroid-stimulating hormone (TSH) and increased free triiodothyronine (FT3) and free thyroxine (FT4) concentrations, as well antibodies against both thyroid peroxidase (TPO) and TSH receptors, led to the diagnosis of Graves' disease. The patient received 500MBq of radioiodine (I131). Three months after the radioactive iodine therapy, the thyroid volume was reduced to 30% of pretherapeutic volume. Although the patient was slightly hypothyroidic, his liver enzymes returned to normal, his erythrocytic protoporphyrin concentration dropped fivefold, and his skin symptoms improved dramatically. The coexistence of Graves' disease and EPP is a statistically rare event as, besides our patient, there was one additional case reported in the literature. Although the exact mechanism whereby Graves' disease interacts with EPP is yet to be explored, we recommend testing thyroid function in EPP patients with liver complication to exclude hyperthyroidism as a potential caus
Biochemical and molecular diagnosis of erythropoietic protoporphyria in an Ashkenazi Jewish family
Summary: Erythropoietic protoporphyria (EPP) is a rare hereditary disorder due to a partial deficiency of ferrochelatase (FECH). The genotype of EPP patients features a mutation on one allele of the FECH gene and a common hypomorphic FECH IVS3-48c on the other allele (M/c). The resulting enzyme activity in patients is ∼35% of that in normal individuals. Ferrochelatase deficiency results in the accumulation of protoporphyrin in the skin, which is responsible for the clinical symptom of cutaneous photosensitivity in patients. In this study, we report the identification of a novel FECH mutation delT23 in an 11-member EPP family of Jewish origin. Two EPP siblings shared an identical genotype of delT23/IVS3-48c (M/c). They were both photosensitive and showed highly increased erythrocyte protoporphyrin. The genotype of the patients' mother, who did not present with any EPP clinical symptoms, was delT23/IVS3-48t (M/t). The patients' father, an offspring of consanguineous parents, was homozygous IVS3-48 c/c. He exhibited a mild photosensitivity, and an increase of 4-fold in erythrocyte protoporphyrin. His FECH mRNA amount was 71% of that of genotype t/t. It is the first reported case of an individual with c/c genotype who exhibits both biochemical and clinical indications of EPP. These results suggest that IVS3-48c is a functional variant of ferrochelatase. The clinical symptoms and biochemical abnormalities in the patients' father could be the result of an interaction between genetic and environmental factors. In addition, the frequency of IVS3-48c in the Ashkenazi Jewish population was estimated at 8%, which is similar to that in the European population
Water vapor and the dynamics of climate changes
Water vapor is not only Earth's dominant greenhouse gas. Through the release
of latent heat when it condenses, it also plays an active role in dynamic
processes that shape the global circulation of the atmosphere and thus climate.
Here we present an overview of how latent heat release affects atmosphere
dynamics in a broad range of climates, ranging from extremely cold to extremely
warm. Contrary to widely held beliefs, atmospheric circulation statistics can
change non-monotonically with global-mean surface temperature, in part because
of dynamic effects of water vapor. For example, the strengths of the tropical
Hadley circulation and of zonally asymmetric tropical circulations, as well as
the kinetic energy of extratropical baroclinic eddies, can be lower than they
presently are both in much warmer climates and in much colder climates. We
discuss how latent heat release is implicated in such circulation changes,
particularly through its effect on the atmospheric static stability, and we
illustrate the circulation changes through simulations with an idealized
general circulation model. This allows us to explore a continuum of climates,
constrain macroscopic laws governing this climatic continuum, and place past
and possible future climate changes in a broader context.Comment: 22 pages, 11 figure
Thermodynamics of Quasi-Particles at Finite Chemical Potential
We present in this work a generalization of the solution of Gorenstein and
Yang to the inconsistency problem of thermodynamics for systems of
quasi-particles whose masses depend on both the temperature and the chemical
potential. We work out several solutions for an interacting system of quarks
and gluons and show that there is only one type of solution that reproduce both
perturbative and lattice QCD.Comment: 33 pages, 1 figure. Accepted for publication in Nuclear Physics
Reliability assessment of distribution systems incorporating feeder restoration actions
This paper proposes a computational methodology for the evaluation of the IEEE reliability indices for distribution systems considering distribution system restoration. The goal of the proposed methodology is to move from a reliability assessment based on historical data to a computational approach. The developed tool allows the evaluation of the Service Restoration benefits, in terms of customers interruption duration in case of fault occurrences. Distribution System Restoration (DSR) is aimed at restoring loads after a fault by altering the topological structure of the distribution network while meeting electrical and operational constraints. The Spanning Tree Search algorithm is used to identify a post-outage topology that will restore the maximal amount of load with a minimal number of switching operations. The goal of the proposed tool is to determine the optimal switching sequences for the restoration process. The reliability indices incorporates contributions of all possible faults effects
Precipitate stability and recrystallisation in the weld nuggets of friction stir welded Al-Mg-Si and Al-Mg-Sc alloys
Two different precipitate hardening aluminium alloys processed by friction
stir welding were investigated. The microstructure and the hardness of the as
delivered materials were compared to that of the weld nugget. Transmission
electron microscopy observations combined with three-dimensional atom probe
analyses clearly show that \beta;" precipitates dissolved in the nugget of the
Al-Mg-Si giving rise to some supersaturated solid solution. It is shown that
the dramatic softening of the weld could be partly recovered by post-welding
ageing treatments. In the Al-Mg-Sc alloy, Al3Sc precipitate size and density
are unchanged in the nugget comparing to the base metal. These precipitates
strongly reduce the boundary mobility of recrystallised grains, leading to a
grain size in the nugget much smaller than in the Al-Mg-Si alloy. Both coherent
and incoherent precipitates were detected. This feature may indicate that a
combination of continuous and discontinuous recrystallisation occurred in the
weld nugget
In The Neighbourhood of Tame Monsters: A study of galaxies near low-redshift quasars
The impact of quasars on their galaxy neighbours is an important factor in
the understanding of galaxy evolution models. The aim of this work is to
characterize the intermediate-scale environments of quasars at low redshift (z
0.2) with the most statistically complete sample to date using the seventh
data release of the Sloan Digital Sky Survey. We have used 305 quasar-galaxy
associations with spectroscopically measured redshifts within the projected
distance range of 350 kpc, to calculate how surface densities of galaxies,
colors, degree of ionization, dust extinction and star-formation rates change
as a function of the distance to our quasar sample. We also identify the
companion Active Galactic Nuclei from our main galaxy sample and calculate
surface density for different galaxy types. We have done this in three
different quasar-galaxy redshift difference ranges z 0.001, 0.006,
and 0.012. Our results suggest that there is a significant increase of the
surface density of blue neighbours around our low-redshift quasar sample that
is steeper than around non-active field galaxies of the same luminosity and
redshift range. This may indicate that quasar formation is accomplished via a
merging scenario. No significant changes in star formation rate, dust
extinction, degree of ionization or color as a function of distance from the
quasars was observed. We could not observe any effects from quasars on their
companion galaxies.Comment: Submitted to Astronomy & Astrophysics November 22 2011; Accepted into
Astronomy & Astrophysics on April 23 2012. Keywords: active, nuclei, star
formation, quasars: general, interactions, evolutio
- …