| 1. |
- Thompson, B.A., et al.
(författare)
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Application of a 5-tiered scheme for standardized classification of 2,360 unique mismatch repair gene variants in the InSiGHT locus-specific database
- 2014
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 46:2, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- The clinical classification of hereditary sequence variants identified in disease-related genes directly affects clinical management of patients and their relatives. The International Society for Gastrointestinal Hereditary Tumours (InSiGHT) undertook a collaborative effort to develop, test and apply a standardized classification scheme to constitutional variants in the Lynch syndrome-associated genes MLH1, MSH2, MSH6 and PMS2. Unpublished data submission was encouraged to assist in variant classification and was recognized through microattribution. The scheme was refined by multidisciplinary expert committee review of the clinical and functional data available for variants, applied to 2,360 sequence alterations, and disseminated online. Assessment using validated criteria altered classifications for 66% of 12,006 database entries. Clinical recommendations based on transparent evaluation are now possible for 1,370 variants that were not obviously protein truncating from nomenclature. This large-scale endeavor will facilitate the consistent management of families suspected to have Lynch syndrome and demonstrates the value of multidisciplinary collaboration in the curation and classification of variants in public locus-specific databases. © 2014 Nature America, Inc.
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| 2. |
- Dahl-Jensen, D., et al.
(författare)
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Eemian interglacial reconstructed from a Greenland folded ice core
- 2013
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 493:7433, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
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| 3. |
- Abbott, Peter M., et al.
(författare)
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A detailed framework of Marine Isotope Stages 4 and 5 volcanic events recorded in two Greenland ice-cores
- 2012
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 36, s. 59-77
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Tidskriftsartikel (refereegranskat)abstract
- Sulphate records from Greenland ice-cores indicate that Marine Isotope Stages 4 and 5 were charactensed by a higher incidence of large volcanic eruptions than other periods during the last glacial period, however, few investigations have focused on tephra deposits associated with these volcanic eruptions and the nature and origin of the events. Here we present a detailed tephrochronological framework of the products of 15 volcanic events spanning this interval: the majority of which have been preserved as cryptotephra horizons within the Greenland records. The major element compositions of individual glass shards within these horizons indicate that 13 of the eruptions originated from Iceland and 6 of these events can be correlated to the specific volcanic systems of Katla, Grimsvotn, Grimsvotn-Kverkfjoll and either Reykjanes or Veidivotn-Bardarbunga. For the remaining Icelandic horizons a source from either the rift zone or a flank zone can be suggested based on rock suite affinities. Two horizons have been correlated to a source from the Jan Mayen volcanic system which represents the first discovery of material from this system within any Greenland ice-cores. The robust geochemical characterisations, independent ages for these horizons (derived from the GICCO5 ice-core chronology) and stratigraphic positions relative to the Dansgaard-Oeschger climate events recorded in the Greenland ice-cores represent a critical framework that provides new information on the frequency and nature of volcanic events occurring in the North Atlantic region during MIS 4 and 5. This framework can now be utilised in the assessment of the differential timing and rate of response to the millennial-scale climatic events that characterised this period, through the use of the tephra horizons as time-synchronous tie-lines to other palaeoclimatic sequences.
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| 4. |
- Davies, Siwan M., et al.
(författare)
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Tracing volcanic events in the NGRIP ice-core and synchronising North Atlantic marine records during the last glacial period
- 2010
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 0012-821X .- 1385-013X. ; 294, s. 69-79
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Five basaltic tephra horizons have been identified in the NGRIP ice-core during the last glacial period. Geochemical analyses indicate that these tephras are of Icelandic origin with one horizon identified as the Faroe Marine Ash Zone III (FMAZ III) — an important marker horizon in several marine records within the Faroe Islands margin. The FMAZ III is a few millimetres thick and is constrained to 38,122 ± 723 yr b2k (before year AD 2000) according to the Greenland Ice Core Chronology (GICC05). This event falls directly at the thermal peak of Greenland Interstadial 8 (GI-8) and a marine-ice correlation, based on the position of this tephra, suggests a close coupling of the marine and atmospheric systems at this time. The remaining tephras originate from the Eastern Volcanic Zone with the Katla volcanic system pinpointed as the dominant source. These are thought to represent previously unknown volcanic events which add considerably to our knowledge of Icelandic volcanism during this period. Independent ages are assigned to these events and together with major element characterisation, form the backbone of the tephrochronology framework presented here. Despite the identification of these tephras, this study also demonstrates that the sulphate record may not always act as a suitable proxy for the identification of tephra horizons in ice-core records.
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| 5. |
- Jonsson, Christina E., et al.
(författare)
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High-resolution diatom delta O-18 records, from the last 150 years, reflecting changes in amount of winter precipitation in two sub-Arctic high-altitude lakes in the Swedish Scandes
- 2010
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Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 25:6, s. 918-930
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Tidskriftsartikel (refereegranskat)abstract
- Waters from high-altitude alpine lakes are mainly recharged by meteoric water. Because of seasonal variations in precipitation and temperature and relatively short hydraulic residence times, most high-altitude lakes have lake water isotopic compositions (delta O-18(lake)) that fluctuate due to seasonality in water balance processes. Input from snowmelt, in particular, has a significant role in determining lake water delta O-18. Here we compare two high-resolution delta O-18(diatom) records from lake sediments in the Swedish Scandes with instrumental data from the last century obtained from nearby meteorological stations. The time period AD 1900-1990 is characterised by an increase in winter precipitation and high winter/summer precipitation ratios and this is recorded in delta O-18(diatom) as decreasing trends. Lowest delta O-18(diatom) values and highest amount of winter precipitation are found around AD 1990 when the winter North Atlantic Oscillation index was above +2. We conclude that for the last 150 a the main factor affecting the delta O-18(diatom) signal in these sub-Arctic high-altitude lakes with short residence times has been changes in amount of winter precipitation and that delta O-18(diatom) derived from high-altitude lakes in the Swedish Scandes can be used as a winter precipitation proxy.
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| 6. |
- Jonsson, Christina E, et al.
(författare)
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High resolution diatom δ18O records from two sub-Arctic high altitude lakes in the Swedish Scandes
- 2010
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Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 25:6, s. 918-930
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Tidskriftsartikel (refereegranskat)abstract
- Waters from high-altitude alpine lakes are mainly recharged by meteoric water. Because of seasonal variations in precipitation and temperature and relatively short hydraulic residence times, most high-altitude lakes have lake water isotopic compositions (δ18Olake) that fluctuate due to seasonality in water balance processes. Input from snowmelt, in particular, has a significant role in determining lake water δ18O. Here we compare two high-resolution δ18Odiatom records from lake sediments in the Swedish Scandes with instrumental data from the last century obtained from nearby meteorological stations. The time period AD 1900–1990 is characterised by an increase in winter precipitation and high winter/summer precipitation ratios and this is recorded in δ18Odiatom as decreasing trends. Lowest δ18Odiatom values and highest amount of winter precipitation are found around AD 1990 when the winter North Atlantic Oscillation index was above +2. We conclude that for the last 150 a the main factor affecting the δ18Odiatom signal in these sub-Arctic high-altitude lakes with short residence times has been changes in amount of winter precipitation and that δ18Odiatom derived from high-altitude lakes in the Swedish Scandes can be used as a winter precipitation proxy. Copyright © 2010 John Wiley & Sons, Ltd.
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| 7. |
- Rosqvist, Gunhild C., et al.
(författare)
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Shifts in precipitation during the last millennium in northern Scandinavia from lacustrine isotope records
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 66, s. 22-34
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Tidskriftsartikel (refereegranskat)abstract
- Here we present delta P-18(diatom) data from two high-latitude lakes; one has short residence time and a water isotopic composition (delta O-18(lake)) that fluctuate due to seasonal variations in precipitation and temperature, and the other has delta O-18(lake) that is influenced by longer lake water residence times and evaporation. The delta O-18(diatom) records reveal common responses to precipitation forcing over the past millennium. Relatively wet summers are inferred from delta O-18(diatom) between 1000 and 1080 AD, 1300 and 1440 AD, and during the early 19th century, coincided with periods of high cloud cover inferred from tree-ring carbon isotopes, and other data for high Arctic Oscillation index. While relatively dry summers with increasing influence of winter snow are indicated between 1600 and 1750 AD. The co-response between carbon isotopes in trees and oxygen isotopes in diatoms strengthens the relationship between cloud cover and precipitation and the hypothesis that these changes were the result of significant regional shifts in atmospheric circulation.
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| 8. |
- Olesen, Pernille J, et al.
(författare)
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A population-based study on the influence of brain atrophy on 20-year survival after age 85.
- 2011
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Ingår i: Neurology. - 0028-3878. ; 76:10, s. 879-86
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Tidskriftsartikel (refereegranskat)abstract
- Individuals aged 80 years and older is the fastest growing segment of the population worldwide. To understand the biology behind increasing longevity, it is important to examine factors related to survival in this age group. The relationship between brain atrophy and survival after age 85 remains unclear.
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| 9. |
- Skoog, Ingmar, 1954, et al.
(författare)
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Head size may modify the impact of white matter lesions on dementia.
- 2012
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Ingår i: Neurobiology of aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 33:7, s. 1186-1193
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to examine whether total intracranial volume (TICV), a marker of premorbid brain size, modified the impact of the apolipoprotein E (apoE) e4 phenotype and ischemic white matter lesions (WMLs) on odds for dementia. The study comprised a population-based sample of 104 demented and 135 nondemented 85-year-olds, and included physical and neuropsychiatric examinations, and head computerized tomography (CT). Dementia disorders were defined according to standard criteria. TICV and WMLs were rated on computerized tomography. Using the highest group as reference, the risk for dementia, Alzheimer's disease (AD), and vascular dementia (VaD) was increased in those with the smallest half, tertile, and quartile of TICV. Smaller TICV increased the odds of dementia, Alzheimer's disease, and vascular dementia in participants with WMLs. WMLs were not associated with increased odds of dementia in those with the largest TICV. The interaction term WMLs*TICV was also significant. TICV did not modify the odds of dementia in those with the apolipoprotein e4 phenotype. Our results suggest that the impact of brain pathology on the risk of dementia is modified by premorbid brain size.
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| 10. |
- Wolff, E. W., et al.
(författare)
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Changes in environment over the last 800,000 years from chemical analysis of the EPICA Dome C ice core
- 2010
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 29:1-2, s. 285-295
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Tidskriftsartikel (refereegranskat)abstract
- The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and sequential ice. Numerous chemical species have been measured along the length of the cores. Here we concentrate on interpreting the main low-resolution patterns of major ions. We extend the published record for non-sea-salt calcium, sea-salt sodium and non-sea-salt sulfate flux to 800 ka. The non-sea-salt calcium record confirms that terrestrial dust originating from South America closely mirrored Antarctic climate, both at orbital and millennial timescales. A major cause of the main trends is most likely climate in southern South America, which could be sensitive to subtle changes in atmospheric circulation. Sea-salt sodium also follows temperature, but With a threshold at low temperature. We re-examine the use of sodium as a sea ice proxy, concluding that it is probably reflecting extent, with high salt concentrations reflecting larger ice extents. With this interpretation, the sodium flux record indicates low ice extent operating as an amplifier in warm interglacials. Non-sea-salt sulfate flux is almost constant along the core, confirming the lack of change in marine productivity (for sulfur-producing organisms) in the areas of the Southern Ocean contributing to the flux at Dome C. For the first time we also present long records of reversible species such as nitrate and chloride, and show that the pattern of post-depositional losses described for shallower ice is maintained in older ice. It appears possible to use these concentrations to constrain snow accumulation rates in interglacial ice at this site, and the results suggest a possible correction to accumulation rates in one early interglacial. Taken together the chemistry records offer a number of constraints on the way the Earth system combined to give the major climate fluctuations of the late Quaternary period.
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