An expanded phylogeny of social amoebas (Dictyostelia) shows increasing diversity and new morphological patterns

<p>Abstract</p> <p>Background</p> <p>Social Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and <it>Dictyostelium discoideum </it>is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned.</p> <p>Results</p> <p>Over the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of the previously established four major groups, violating nearly all previously suggested deep morphological patterns.</p> <p>Conclusions</p> <p>A greatly expanded phylogeny of Dictyostelia now shows even greater morphological plasticity at deep taxonomic levels. In fact, there now seem to be no obvious deep evolutionary trends across the group. However at a finer level, patterns in morphological character evolution are beginning to emerge. These results also suggest that there is a far greater diversity of Dictyostelia yet to be discovered, including novel morphologies.</p

MASEP gamma knife radiosurgery for secretory pituitary adenomas: experience in 347 consecutive cases

<p>Abstract</p> <p>Background</p> <p>Secretory pituitary adenomas are very common brain tumors. Historically, the treatment armamentarium for secretory pituitary adenomas included neurosurgery, medical management, and fractionated radiotherapy. In recent years, MASEP gamma knife radiosurgery (MASEP GKRS) has emerged as an important treatment modality in the management of secretory pituitary adenomas. The goal of this research is to define accurately the efficacy, safety, complications, and role of MASEP GKRS for treatment of secretory pituitary adenomas.</p> <p>Methods</p> <p>Between 1997 and 2007 a total of 347 patients with secretory pituitary adenomas treated with MASEP GKRS and with at least 60 months of follow-up data were identified. In 47 of these patients some form of prior treatment such as transsphenoidal resection, or craniotomy and resection had been conducted. The others were deemed ineligible for microsurgery because of body health or private choice, and MASEP GKRS served as the primary treatment modality. Endocrinological, ophthalmological, and neuroradiological responses were evaluated.</p> <p>Results</p> <p>MASEP GKRS was tolerated well in these patients under the follow-up period ranged from 60 to 90 months; acute radioreaction was rare and 17 patients had transient headaches with no clinical significance. Late radioreaction was noted in 1 patient and consisted of consistent headache. Of the 68 patients with adrenocorticotropic hormone-secreting(ACTH) adenomas, 89.7% showed tumor volume decrease or remain unchanged and 27.9% experienced normalization of hormone level. Of the 176 patients with prolactinomas, 23.3% had normalization of hormone level and 90.3% showed tumor volume decrease or remain unchanged. Of the 103 patients with growth hormone-secreting(GH) adenomas, 95.1% experienced tumor volume decrease or remain unchanged and 36.9% showed normalization of hormone level.</p> <p>Conclusion</p> <p>MASEP GKRS is safe and effective in treating secretory pituitary adenomas. None of the patients in our study experienced injury to the optic apparatus or had other neuropathies related with gamma knife. MASEP GKRS may serve as a primary treatment method in some or as a salvage treatment in the others. However, treatment must be tailored to meet the patient's symptoms, tumor location, tumor morphometry, and overall health. Longer follow-up is required for a more complete assessment of late radioreaction and treatment efficacy.</p

Test System Stability and Natural Variability of a Lemna Gibba L. Bioassay

BACKGROUND: In ecotoxicological and environmental studies Lemna spp. are used as test organisms due to their small size, rapid predominantly vegetative reproduction, easy handling and high sensitivity to various chemicals. However, there is not much information available concerning spatial and temporal stability of experimental set-ups used for Lemna bioassays, though this is essential for interpretation and reliability of results. We therefore investigated stability and natural variability of a Lemna gibba bioassay assessing area-related and frond number-related growth rates under controlled laboratory conditions over about one year. METHODOLOGY/PRINCIPAL FINDINGS: Lemna gibba L. was grown in beakers with Steinberg medium for one week. Area-related and frond number-related growth rates (r(area) and r(num)) were determined with a non-destructive image processing system. To assess inter-experimental stability, 35 independent experiments were performed with 10 beakers each in the course of one year. We observed changes in growth rates by a factor of two over time. These did not correlate well with temperature or relative humidity in the growth chamber. In order to assess intra-experimental stability, we analysed six systematic negative control experiments (nontoxicant tests) with 96 replicate beakers each. Evaluation showed that the chosen experimental set-up was stable and did not produce false positive results. The coefficient of variation was lower for r(area) (2.99%) than for r(num) (4.27%). CONCLUSIONS/SIGNIFICANCE: It is hypothesised that the variations in growth rates over time under controlled conditions are partly due to endogenic periodicities in Lemna gibba. The relevance of these variations for toxicity investigations should be investigated more closely. Area-related growth rate seems to be more precise as non-destructive calculation parameter than number-related growth rate. Furthermore, we propose two new validity criteria for Lemna gibba bioassays: variability of average specific and section-by-section segmented growth rate, complementary to average specific growth rate as the only validity criterion existing in guidelines for duckweed bioassays

Cross-protection against European swine influenza viruses in the context of infection immunity against the 2009 pandemic H1N1 virus : studies in the pig model of influenza

Pigs are natural hosts for the same influenza virus subtypes as humans and are a valuable model for cross-protection studies with influenza. In this study, we have used the pig model to examine the extent of virological protection between a) the 2009 pandemic H1N1 (pH1N1) virus and three different European H1 swine influenza virus (SIV) lineages, and b) these H1 viruses and a European H3N2 SIV. Pigs were inoculated intranasally with representative strains of each virus lineage with 6- and 17-week intervals between H1 inoculations and between H1 and H3 inoculations, respectively. Virus titers in nasal swabs and/or tissues of the respiratory tract were determined after each inoculation. There was substantial though differing cross-protection between pH1N1 and other H1 viruses, which was directly correlated with the relatedness in the viral hemagglutinin (HA) and neuraminidase (NA) proteins. Cross-protection against H3N2 was almost complete in pigs with immunity against H1N2, but was weak in H1N1/pH1N1-immune pigs. In conclusion, infection with a live, wild type influenza virus may offer substantial cross-lineage protection against viruses of the same HA and/or NA subtype. True heterosubtypic protection, in contrast, appears to be minimal in natural influenza virus hosts. We discuss our findings in the light of the zoonotic and pandemic risks of SIVs

Distances and ages of globular clusters using Hipparcos parallaxes of local subdwarfs

We discuss the impact of Population II and Globular Cluster (GCs) stars on the derivation of the age of the Universe, and on the study of the formation and early evolution of galaxies, our own in particular. The long-standing problem of the actual distance scale to Population II stars and GCs is addressed, and a variety of different methods commonly used to derive distances to Population II stars are briefly reviewed. Emphasis is given to the discussion of distances and ages for GCs derived using Hipparcos parallaxes of local subdwarfs. Results obtained by different authors are slightly different, depending on different assumptions about metallicity scale, reddenings, and corrections for undetected binaries. These and other uncertainties present in the method are discussed. Finally, we outline progress expected in the near future.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 22 pages including 3 tables and 2 postscript figures, uses Kluwer's crckapb.sty LaTeX style file, enclose

Kin discrimination and possible cryptic species in the social amoeba Polysphondylium violaceum

Abstract Background The genetic diversity of many protists is unknown. The differences that result from this diversity can be important in interactions among individuals. The social amoeba Polysphondylium violaceum, which is a member of the Dictyostelia, has a social stage where individual amoebae aggregate together to form a multicellular fruiting body with dead stalk cells and live spores. Individuals can either cooperate with amoebae from the same clone, or sort to form clonal fruiting bodies. In this study we look at genetic diversity in P. violaceum and at how this diversity impacts social behavior. Results The phylogeny of the ribosomal DNA sequence (17S to 5.8S region) shows that P. violaceum is made up of at least two groups. Mating compatibility is more common between clones from the same phylogenetic group, though matings between clones from different phylogenetic groups sometimes occurred. P. violaceum clones are more likely to form clonal fruiting bodies when they are mixed with clones from a different group than when they are mixed with a clone of the same group. Conclusion Both the phylogenetic and mating analyses suggest the possibility of cryptic species in P. violaceum. The level of divergence found within P. violaceum is comparable to the divergence between sibling species in other dictyostelids. Both major groups A/B and C/D/E/F show kin discrimination, which elevates relatedness within fruiting bodies but not to the level of clonality. The diminished cooperation in mixes between groups suggests that the level of genetic variation between individuals influences the extent of their cooperation

Outcome after renal transplantation. Part II: Quality of life and psychosocial adjustment

Knowledge of health-related quality of life (QOL) and psychosocial adjustment (PA) in children after renal transplantation (RTPL) is limited. QOL and PA were evaluated by standardized tests in patients after RTPL. Thirty-seven children of median age 14.5 years (range 6.5-17 years) were investigated a mean 4.5 years (range 0.5-12.8 years) after RTPL. Child- and parent-rated QOL was evaluated with the Child Quality of life Questionnaire of The Netherlands Organization for Applied Scientific Research Academical Medical Centre (TNO-AZL). PA was assessed by the Child Behaviour Checklist (CBCL) providing parental reports of a child's behaviour. In patients' self-ratings, the QOL dimension physical complaints (P < 0.0005) scored significantly better than that of healthy controls, whereas the dimension positive emotional functioning was impaired (P = 0.02). Parents rated motor functioning (P = 0.002), autonomy (P = 0.01), cognition (P = 0.04) and positive emotions (P < 0.0005) as significantly impaired. Parents also assessed PA significantly (P = 0.02) impaired with regard to internalizing behaviour. Dialysis duration, young age at RTPL, living-related donation, steroid treatment, adverse family relationships and maternal distress had a significantly negative impact on QOL and PA (P < 0.05). Patients rated QOL higher than did healthy controls. Parents evaluated their children's QOL and PA more pessimistically than did the patients themselves. Both illness-related variables and family environment played an important role

Evolutionary and pulsational properties of white dwarf stars

Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. They can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants. In this work, we review the essentials of the physics of white dwarf stars. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.Comment: 85 pages, 28 figures. To be published in The Astronomy and Astrophysics Revie

Posttraumatic stress disorder (PTSD) in children after paediatric intensive care treatment compared to children who survived a major fire disaster

<p>Abstract</p> <p>Background</p> <p>The goals were to determine the presence of posttraumatic stress disorder (PTSD) in children after paediatric intensive care treatment, to identify risk factors for PTSD, and to compare this data with data from a major fire disaster in the Netherlands.</p> <p>Methods</p> <p>Children completed the Dutch Children's Responses to Trauma Inventory at three and nine months after discharge from the paediatric intensive care unit (PICU). Comparison data were available from 355 children survivors who completed the same questionnaire 10 months after a major fire disaster.</p> <p>Results</p> <p>Thirty-six children aged eight to 17 years completed questionnaires at three month follow-up, nine month follow-up, or both. More than one third (34.5%) of the children had subclinical PTSD, while 13.8% were likely to meet criteria for PTSD. Maternal PTSD was the strongest predictor for child PTSD. There were no significant differences in (subclinical) PTSD symptoms either over time or compared to symptoms of survivors from the fire disaster.</p> <p>Conclusion</p> <p>This study shows that a considerable number of children have persistent PTSD after PICU treatment. Prevention of PTSD is important to minimize the profound adverse effects that PTSD can have on children's well-being and future development.</p

Sleep Loss Produces False Memories

People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b) as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., “night”, “dark”, “coal”,…), lacking the strongest common associate or theme word (here: “black”). Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss