| 1. |
- A Hulten, Maj, et al.
(författare)
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On the origin of the maternal age effect in trisomy 21 Down syndrome: the Oocyte Mosaicism Selection model
- 2010
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Ingår i: Reproduction. - 1470-1626 .- 1476-3990. ; 139:1, s. 1-9
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Forskningsöversikt (refereegranskat)abstract
- We have recently documented that trisomy 21 mosaicism is common in human foetal ovaries. On the basis of this observation we propose that the maternal age effect in Down syndrome (DS) is caused by the differential behaviour of trisomy 21 in relation to disomy 21 oocytes during development from foetal life until ovulation in adulthood. in particular, we suggest that trisomy 21 oocytes, lagging behind those that are disomic, may escape the timed pruning of the seven million in foetal life to the 300-400 finally selected for ovulation. The net effect of this preferential elimination will be an accumulation of trisomy 21 oocytes in the ovarian reserve of older women. We here highlight the implications of this Oocyte Mosaicism Selection (OMS) model with respect to the prevalent view that the maternal age effect is complex, dependent on many different biological and environmental factors. We examine conclusions drawn from recent large-scale studies in families, tracing DNA markers along the length of chromosome 21q between parents and DS children, in comparison to the OMS model. We conclude that these family linkage data are equally compatible with the maternal age effect originating from the accumulation of trisomy 21 oocytes with advancing maternal age. One relatively straightforward way to get to grips with what is actually going on in this regard would be to compare incidence of trisomy 21 oocytes (and their pairing configurations) in foetal ovaries with that in oocytes at the meiosis I stage from adult women.
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| 2. |
- Abbott, Jessica K.
(författare)
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Intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic animals
- 2011
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 278:1703, s. 161-169
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Forskningsöversikt (refereegranskat)abstract
- Intra-locus sexual conflict results when sex-specific selection pressures for a given trait act against the intra-sexual genetic correlation for that trait. It has been found in a wide variety of taxa in both laboratory and natural populations, but the importance of intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic organisms has rarely been considered. This is not so surprising given the conceptual and theoretical association of intra-locus sexual conflict with sexual dimorphism, but there is no a priori reason why intra-locus sexual conflict cannot occur in hermaphroditic organisms as well. Here, I discuss the potential for intra-locus sexual conflict in hermaphroditic animals and review the available evidence for such conflict, and for the existence of sexually antagonistic genetic variation in hermaphrodites. I argue that mutations with asymmetric effects are particularly likely to be important in mediating sexual antagonism in hermaphroditic organisms. Moreover, sexually antagonistic genetic variation is likely to play an important role in inter-individual variation in sex allocation and in transitions to and from gonochorism (separate sexes) in simultaneous hermaphrodites. I also describe how sequential hermaphrodites may experience a unique form of intra-locus sexual conflict via antagonistic pleiotropy. Finally, I conclude with some suggestions for further research.
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| 3. |
- Abbott, Jessica K., et al.
(författare)
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Obtaining snapshots of genetic variation using hemiclonal analysis
- 2011
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Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 26:7, s. 359-368
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Forskningsöversikt (refereegranskat)abstract
- Hemiclones are naturally occurring or artificially produced individuals that share a single specific genetic haplotype. Natural hemiclones are produced via hybridization between two closely related species, whereas hemiclonal analysis in Drosophila is carried out in the laboratory via crosses with artificially created 'clone-generator' females with a specific genetic make-up. Hemiclonal analysis in Drosophila has been applied successfully to date to obtain measures of standing genetic variation for numerous traits. Here, we review the current hemiclonal literature and suggest future directions for hemiclonal research, including its application in molecular and genomic studies, and the adaptation of natural hemiclonal systems to carry out Drosophila-type studies of standing genetic variation.
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| 4. |
- Abdo, A. A., et al.
(författare)
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PKS 1502+106 : A new and distant gamma-ray blazar in outburst discovered by the fermi large area telescope
- 2010
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 710:1, s. 810-827
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Forskningsöversikt (refereegranskat)abstract
- The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope discovered a rapid (similar to 5 days duration), high-energy (E > 100 MeV) gamma-ray outburst from a source identified with the blazar PKS 1502+106 (OR 103, S3 1502+10, z = 1.839) starting on 2008 August 5 (similar to 23 UTC, MJD 54683.95), and followed by bright and variable flux over the next few months. Results on the gamma-ray localization and identification, as well as spectral and temporal behavior during the first months of the Fermi all-sky survey, are reported here in conjunction with a multiwaveband characterization as a result of one of the first Fermi multifrequency campaigns. The campaign included a Swift ToO (followed up by a 16 day observation on August 7-22, MJD 54685-54700), VLBA (within the MOJAVE program), Owens Valley Radio Observatory (OVRO) 40 m, Effelsberg-100 m, Metsahovi-14 m, RATAN-600, and Kanata-Hiroshima radio/optical observations. Results from the analysis of archival observations by INTEGRAL, XMM-Newton, and Spitzer space telescopes are reported for a more complete picture of this new gamma-ray blazar. PKS 1502+106 is a sub-GeV peaked, powerful flat spectrum radio quasar (luminosity at E > 100 MeV, L-gamma, is about 1.1 x 10(49) erg s(-1), and black hole mass likely close to 10(9) M-circle dot), exhibiting marked gamma-ray bolometric dominance, in particular during the asymmetric outburst (L-gamma/L-opt similar to 100, and 5 day averaged flux F-E > 100MeV = 2.91 +/- 1.4 x 10(-6) ph cm(-2) s(-1)), which was characterized by a factor greater than 3 of flux increase in less than 12 hr. The outburst was observed simultaneously from optical to X-ray bands (F0.3-10keV = 2.18(-0.12)(+0.15) x 10(-12) erg cm(-2) s(-1), and hard photon index similar to 1.5, similar to past values) with a flux increase of less than 1 order of magnitude with respect to past observations, and was likely controlled by Comptonization of external-jet photons produced in the broad-line region (BLR) in the gamma-ray band. No evidence of a possible blue bump signature was observed in the optical-UV continuum spectrum, while some hints for a possible 4 day time lag with respect to the gamma-ray flare were found. Nonetheless, the properties of PKS 1502+106 and the strict optical/UV, X-, and gamma-ray cross-correlations suggest the contribution of the synchrotron self-Compton (SSC), in-jet, process should dominate from radio to X- rays. This mechanism may also be responsible for the consistent gamma-ray variability observed by the LAT on longer timescales, after the ignition of activity at these energies provided by the BLR-dissipated outburst. Modulations and subsequent minor, rapid flare events were detected, with a general fluctuation mode between pink-noise and a random-walk. The averaged gamma-ray spectrum showed a deviation from a simple power law, and can be described by a log-parabola curved model peaking around 0.4-0.5 GeV. The maximum energy of photons detected from the source in the first four months of LAT observations was 15.8 GeV, with no significant consequences on extragalactic background light predictions. A possible radio counterpart of the gamma-ray outburst can be assumed only if a delay of more than three months is considered on the basis of opacity effects at cm and longer wavelengths. The rotation of the electric vector position angle observed by VLBA from 2007 to 2008 could represent a slow field odering and alignment with respect to the jet axis, likely a precursor feature of the ejection of a superluminal radio knot and the high-energy outburst. This observing campaign provides more insight into the connection between MeV-GeV flares and the moving, polarized structures observed by the VLBI.
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| 5. |
- Abouassaly, Robert, et al.
(författare)
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Sequelae of Treatment in Long-term Survivors of Testis Cancer
- 2011
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Ingår i: European Urology. - : Elsevier BV. - 1873-7560 .- 0302-2838. ; 60:3, s. 516-526
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Forskningsöversikt (refereegranskat)abstract
- Context: Testicular cancer patients are often diagnosed at a young age, and because of the advances in the treatment of this disease, the vast majority have a normal life expectancy after therapy. Thus, recognition of the long-term sequelae of treatment (ie, surgery, radiation therapy, and chemotherapy) is particularly important in these patients. Objective: To review the adverse effects and the risk of secondary malignancy in long-term survivors of testicular cancer. Evidence acquisition: We conducted a Medline search to identify original articles and reviews on the long-term effects of testicular cancer treatment. Although the search included articles from January 1948 to February 2011, the majority of the included articles were published in the last two decades. Evidence synthesis: All studies examining the long-term sequelae of treatment in testicular cancer are retrospective in nature, with most classified as cohort, case-control, and/or epidemiologic studies. Given that no standardized method of reporting long-term complications exists, evidence synthesis is limited. Conclusions: Recent evidence suggests an increased risk of cardiovascular disease, neurotoxicity, and mild reductions in renal function in survivors of testicular cancer. Treatment of testicular malignancy can also negatively affect gonadal function and fertility and has been shown to result in an increased risk of solid malignancy and leukemia. (C) 2011 European Association of Urology. Published by Elsevier B.V. All rights reserved.
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| 6. |
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| 7. |
- Achatz, Johannes Georg, et al.
(författare)
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Systematic revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology
- 2010
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - : Hindawi Limited. - 0947-5745 .- 1439-0469. ; 48:1, s. 9-32
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Forskningsöversikt (refereegranskat)abstract
- We have used newly discerned morphological characters as well as molecular-sequence data from 18S and 28S rDNA to revise the families recently designated as the '9+0' acoels - what we call Convolutida. Characters from the ultrastructure of sperm, with their '9+0' axonemes, are useful in delineating the Convolutida, but are either species-specific or too conserved within the group to be used to infer relationships within it. Male genital organs, prostatoid organs, and sagittocysts, on the other hand, give a good phylogenetic signal for reconstructing relationships of such genera as Conaperta, Anaperus, and Achoerus; some features of the reproductive organs correlate with habitat and show how the Convolutida probably originated as epiphytic predators and radiated into the mesopsammon, pelagic, and coral-associated realms. In this revision of the Convolutida we provide revised synopses of its families - which we restrict to the Anaperidae, Convolutidae, and Sagittiferidae - and describe a new species, Polychoerus gordoni, from New Zealand. We transfer the genus Adenopea from the Antroposthiidae to the Convolutidae; Conaperta, Neochildia, and Oxyposthia from the Convolutidae to the Anaperidae; Paranaperus and Praeanaperus from the Anaperidae to the Haploposthiidae. Convoluta aegyptica is synonymized with Convoluta boehmigi, Convoluta lacazii with Convoluta sordida, and the genus Picola (Convolutidae) with Deuterogonaria (Haploposthiidae). Amphiscolops blumi, A. carvalhoi, and A. langerhansi, all of which possess a cellular seminal bursa, are transferred to the genus Heterochaerus. Convoluta elegans and Pseudanaperus tinctus are classified as nomina nuda. We use our findings on the ultrastructure of female genital organs and spermatozoa to show that sexual conflict plays a major role in the evolution of diversity of these structures and that the phylogeny of the Acoela would comprise early forms without female genital organs and hyper- or hypodermal transfer of sperm through advanced forms with ever longer and narrower bursal nozzles and sperm with axial microtubules. Moreover, our results show that the acquisition of endosymbiotic algae happened at least twice within the Acoela.
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| 8. |
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| 9. |
- Acosta, Rafael, et al.
(författare)
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A Clinical Review of 9 Years of Free Perforator Flap Breast Reconstructions : An Analysis of 675 Flaps and the Influence of New Techniques on Clinical Practice
- 2011
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Ingår i: Journal of reconstructive microsurgery. - : Georg Thieme Verlag KG. - 0743-684X .- 1098-8947. ; 27:2, s. 91-98
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Forskningsöversikt (refereegranskat)abstract
- The aim of this study is to review our 9-year experience with deep inferior epigastric perforator (DIEP) breast reconstructions to help others more easily overcome the pitfalls we experienced. A chart review was conducted for all 543 patients who had 622 DIEP breast reconstructions in our clinic between January 2000 and January 2009. In this time, there were an additional 28 superior gluteal artery perforator and 25 superficial inferior epigastric artery reconstructions, bringing the total free flap reconstructions to 675. In the early years, the success rate was 90.7%, the average operative time was 7 hours and 18 minutes, and the complication rate was 33.3%; these have improved to 98.2%, 4 hours and 8 minutes, and 19.3%, respectively. We describe our selection criteria, preoperative vascular mapping, surgical techniques, and postoperative monitoring as they relate to these improvements in outcome, operative time, and complications. The DIEP flap is a safe and reliable option in breast reconstructions. By acquiring experience with the flap and introducing new and improving existing techniques we have improved the ease of the procedure and the success rate and have shortened the operative time.
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| 10. |
- Afzal, Wasif, et al.
(författare)
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On the application of genetic programming for software engineering predictive modeling : A systematic review
- 2011
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Ingår i: Expert Systems with Applications. - : Pergamon-Elsevier Science Ltd. - 0957-4174 .- 1873-6793. ; 38:9, s. 11984-11997
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Forskningsöversikt (refereegranskat)abstract
- The objective of this paper is to investigate the evidence for symbolic regression using genetic programming (GP) being an effective method for prediction and estimation in software engineering, when compared with regression/machine learning models and other comparison groups (including comparisons with different improvements over the standard GP algorithm). We performed a systematic review of literature that compared genetic programming models with comparative techniques based on different independent project variables. A total of 23 primary studies were obtained after searching different information sources in the time span 1995-2008. The results of the review show that symbolic regression using genetic programming has been applied in three domains within software engineering predictive modeling: (i) Software quality classification (eight primary studies). (ii) Software cost/effort/size estimation (seven primary studies). (iii) Software fault prediction/software reliability growth modeling (eight primary studies). While there is evidence in support of using genetic programming for software quality classification, software fault prediction and software reliability growth modeling: the results are inconclusive for software cost/effort/size estimation.
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