2,121 research outputs found
Disease flare of ankylosing spondylitis presenting as reactive arthritis with seropositivity: a case report
<p>Abstract</p> <p>Introduction</p> <p>Concurrent rheumatoid factor seropositivity is occasionally detected in ankylosing spondylitis and often causes confusion in clinical routine. Overlap between various seronegative arthritides is a known but uncommon association. Differentiation of spondyloarthropathy from rheumatoid arthritis is important, since the natural history, complications, treatments and prognosis of the two diseases differ significantly.</p> <p>Case presentation</p> <p>Here, we report the case of a 47-year-old Sri Lankan man who had a long history of intermittent joint pains worsening following a recent episode of self-resolving non-bloody diarrhea. Subsequently, he developed a skin rash suggestive of keratoderma blenorrhagica and circinate balanitis. He had classical radiological evidence of ankylosing spondylosis (previously undiagnosed) associated with human leukocyte antigen B27 antigen, but was positive for rheumatoid factor.</p> <p>Conclusions</p> <p>A disease flare of ankylosing spondylitis prompted by a minor diarrheal illness showing well documented features of reactive arthritis is remarkable. The prognostic implications of seropositivity in spondyloarthritis are discussed.</p
Fast estimation of the difference between two PAM/JTT evolutionary distances in triplets of homologous sequences
BACKGROUND: The estimation of the difference between two evolutionary distances within a triplet of homologs is a common operation that is used for example to determine which of two sequences is closer to a third one. The most accurate method is currently maximum likelihood over the entire triplet. However, this approach is relatively time consuming. RESULTS: We show that an alternative estimator, based on pairwise estimates and therefore much faster to compute, has almost the same statistical power as the maximum likelihood estimator. We also provide a numerical approximation for its variance, which could otherwise only be estimated through an expensive re-sampling approach such as bootstrapping. An extensive simulation demonstrates that the approximation delivers precise confidence intervals. To illustrate the possible applications of these results, we show how they improve the detection of asymmetric evolution, and the identification of the closest relative to a given sequence in a group of homologs. CONCLUSION: The results presented in this paper constitute a basis for large-scale protein cross-comparisons of pairwise evolutionary distances
TISs-ST: a web server to evaluate polymorphic translation initiation sites and their reflections on the secretory targets
<p>Abstract</p> <p>Background</p> <p>The nucleotide sequence flanking the translation initiation codon (start codon context) affects the translational efficiency of eukaryotic mRNAs, and may indicate the presence of an alternative translation initiation site (TIS) to produce proteins with different properties. Multi-targeting may reflect the translational variability of these other protein forms. In this paper we present a web server that performs computations to investigate the usage of alternative translation initiation sites for the synthesis of new protein variants that might have different functions.</p> <p>Results</p> <p>An efficient web-based tool entitled TISs-ST (Translation Initiation Sites and Secretory Targets) evaluates putative translation initiation sites and indicates the prediction of a signal peptide of the protein encoded from this site. The TISs-ST web server is freely available to both academic and commercial users and can be accessed at <url>http://ipe.cbmeg.unicamp.br/pub/TISs-ST</url>.</p> <p>Conclusion</p> <p>The program can be used to evaluate alternative translation initiation site consensus with user-specified sequences, based on their composition or on many position weight matrix models. TISs-ST provides analytical and visualization tools for evaluating the periodic frequency, the consensus pattern and the total information content of a sequence data set. A search option allows for the identification of signal peptides from predicted proteins using the PrediSi software.</p
A Similar but Distinctive Pattern of Impaired Cortical Excitability in First-Episode Schizophrenia and ADHD
Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice
Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals,
there are two converging apoptosis pathways: the âextrinsicâ pathway, which is triggered by engagement of cell surface âdeath
receptorsâ such as Fas/APO-1; and the âintrinsicâ pathway, which is triggered by diverse cellular stresses, and is regulated by prosurvival
and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the proapoptotic
proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To
investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1
transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional
Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the
macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was
striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells
(TCRÎČ+
CD4â
CD8â
B220+
) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr
mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating
autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene
by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell
population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the
development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other
haemopoietic cell types
Dusty Planetary Systems
Extensive photometric stellar surveys show that many main sequence stars show
emission at infrared and longer wavelengths that is in excess of the stellar
photosphere; this emission is thought to arise from circumstellar dust. The
presence of dust disks is confirmed by spatially resolved imaging at infrared
to millimeter wavelengths (tracing the dust thermal emission), and at optical
to near infrared wavelengths (tracing the dust scattered light). Because the
expected lifetime of these dust particles is much shorter than the age of the
stars (>10 Myr), it is inferred that this solid material not primordial, i.e.
the remaining from the placental cloud of gas and dust where the star was born,
but instead is replenished by dust-producing planetesimals. These planetesimals
are analogous to the asteroids, comets and Kuiper Belt objects (KBOs) in our
Solar system that produce the interplanetary dust that gives rise to the
zodiacal light (tracing the inner component of the Solar system debris disk).
The presence of these "debris disks" around stars with a wide range of masses,
luminosities, and metallicities, with and without binary companions, is
evidence that planetesimal formation is a robust process that can take place
under a wide range of conditions. This chapter is divided in two parts. Part I
discusses how the study of the Solar system debris disk and the study of debris
disks around other stars can help us learn about the formation, evolution and
diversity of planetary systems by shedding light on the frequency and timing of
planetesimal formation, the location and physical properties of the
planetesimals, the presence of long-period planets, and the dynamical and
collisional evolution of the system. Part II reviews the physical processes
that affect dust particles in the gas-free environment of a debris disk and
their effect on the dust particle size and spatial distribution.Comment: 68 pages, 25 figures. To be published in "Solar and Planetary
Systems" (P. Kalas and L. French, Eds.), Volume 3 of the series "Planets,
Stars and Stellar Systems" (T.D. Oswalt, Editor-in-chief), Springer 201
Cytogerontology since 1881: A reappraisal of August Weismann and a review of modern progress
Cytogerontology, the science of cellular ageing, originated in 1881 with the prediction by August Weismann that the somatic cells of higher animals have limited division potential. Weismann's prediction was derived by considering the role of natural selection in regulating the duration of an organism's life. For various reasons, Weismann's ideas on ageing fell into neglect following his death in 1914, and cytogerontology has only reappeared as a major research area following the demonstration by Hayflick and Moorhead in the early 1960s that diploid human fibroblasts are restricted to a finite number of divisions in vitro.
In this review we give a detailed account of Weismann's theory, and we reveal that his ideas were both more extensive in their scope and more pertinent to current research than is generally recognised. We also appraise the progress which has been made over the past hundred years in investigating the causes of ageing, with particular emphasis being given to (i) the evolution of ageing, and (ii) ageing at the cellular level. We critically assess the current state of knowledge in these areas and recommend a series of points as primary targets for future research
Circadian changes and sex-related differences in fetal heart rate parameters
BACKGROUND: Previous researchers have studied circadian changes in the fetal heart rate (FHR) on small sample sizes and in a strictly controlled environment. This study was undertaken to investigate these changes during the late second and third trimesters, using a portable fetal electrocardiogram recording device (Monica AN24) in pregnant women in home and hospital environments with unrestricted mobility.
METHODS: This was a prospective cohort study of 54 pregnant women with uncomplicated singleton pregnancies between 25 and 40 weeks gestation. FHR recordings were made up to 16 h at home or in the hospital setting in the United Kingdom. FHR data over 90 min periods were averaged and the day (7:00 am-11:00 pm) and night (11:00 pm-7:00 am) data from the same individual were compared. Data were examined for evidence of sex-related differences.
RESULTS: During the night, there was a significant reduction in basal heart rate (bFHR) and a significant increase in short term variation (STV) and long term variation (LTV) (Pâ<â0.05). Basal FHR decreased (Pâ<â0.002), whereas LTV increased (Pâ=â0.014) with advancing gestation. Male fetuses showed greater day: night variation than females regardless of gestation (Pâ=â0.014). There was a higher bFHR in fetuses monitored during the day in hospital (Pâ=â0.04).
CONCLUSION: This study demonstrates that there are sex-, environment and time-related differences in the FHR parameters measured. These differences may need to be considered taken when interpreting FHR data
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