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- Callaghan, Terry, et al.
(författare)
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Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 2. |
- van Es, Michael A, et al.
(författare)
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Angiogenin variants in Parkinson disease and amyotrophic lateral sclerosis
- 2011
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Ingår i: Annals of Neurology. - : Wiley-Blackwell. - 0364-5134 .- 1531-8249. ; 70:6, s. 964-973
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Several studies have suggested an increased frequency of variants in the gene encoding angiogenin (ANG) in patients with amyotrophic lateral sclerosis (ALS). Interestingly, a few ALS patients carrying ANG variants also showed signs of Parkinson disease (PD). Furthermore, relatives of ALS patients have an increased risk to develop PD, and the prevalence of concomitant motor neuron disease in PD is higher than expected based on chance occurrence. We therefore investigated whether ANG variants could predispose to both ALS and PD.METHODS: We reviewed all previous studies on ANG in ALS and performed sequence experiments on additional samples, which allowed us to analyze data from 6,471 ALS patients and 7,668 controls from 15 centers (13 from Europe and 2 from the USA). We sequenced DNA samples from 3,146 PD patients from 6 centers (5 from Europe and 1 from the USA). Statistical analysis was performed using the variable threshold test, and the Mantel-Haenszel procedure was used to estimate odds ratios.RESULTS: Analysis of sequence data from 17,258 individuals demonstrated a significantly higher frequency of ANG variants in both ALS and PD patients compared to control subjects (p = 9.3 × 10(-6) for ALS and p = 4.3 × 10(-5) for PD). The odds ratio for any ANG variant in patients versus controls was 9.2 for ALS and 6.7 for PD.INTERPRETATION: The data from this multicenter study demonstrate that there is a strong association between PD, ALS, and ANG variants. ANG is a genetic link between ALS and PD.
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| 7. |
- Biressi, A., et al.
(författare)
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Wound healing and arm regeneration in Ophioderma longicaudum and Amphiura filiformis (Ophiuroidea, Echinodermata): comparative morphogenesis and histogenesis
- 2010
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Ingår i: Zoomorphology. - : Springer Science and Business Media LLC. - 0720-213X .- 1432-234X. ; 129:1, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- All species of the Ophiuroidea have exceptional regenerative capabilities; in particular, they can replace arms lost following traumatic or self-induced amputation. In order to reconstruct this complex phenomenon, we studied arm regeneration in two different ophiuroids, Ophioderma longicaudum (Retzius, 1805) and Amphiura filiformis O. F. Muller, 1776, which are quite distantly related. These species present contrasting regeneration and differentiation rates and differ in several ecological traits. The aim of this paper is to interpret the primary sequence of morphogenetic and histogenetic events leading to the complete reconstruction of a new arm, comparing the arm regenerative processes of these two ophiuroid species with those described in crinoids. Arm regeneration in ophiuroids is considered an epimorphic process in which new structures develop from a typical blastema formed from an accumulation of presumptive undifferentiated cells. Our results showed that although very different in some respects such as, for instance, the regeneration rate (0.17 mm/week for O. longicaudum and 0.99 mm/week for A. filiformis), morphogenetic and histogenetic aspects are surprisingly similar in both species. The regenerative process presents similar characteristics and follows a developmental scheme which can be subdivided into four phases: a repair phase, an early regenerative phase, an intermediate regenerative phase and an advanced regenerative phase. In terms of histogenesis, the regenerative events involve the development of new structures from migratory pluripotent cells, which proliferate actively, in addition in both cases there is a significant contribution from dedifferentiated cells, in particular dedifferentiating myocytes, although to varying extents. This evidence confirms the plasticity of the regenerative phenomenon in echinoderms, which can apparently follow different pathways in terms of growth and morphogenesis, but nevertheless involve both epimorphic and morphallactic contributions at the cellular level.
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| 8. |
- Blomgren, Lena, 1957-, et al.
(författare)
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Late follow-up of a randomized trial of routine duplex imaging before varicose vein surgery
- 2011
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Ingår i: British Journal of Surgery. - : Oxford University Press (OUP). - 0007-1323 .- 1365-2168. ; 98:8, s. 1112-1116
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Tidskriftsartikel (refereegranskat)abstract
- Background: Routine preoperative duplex examination led to an improvement in results 2 years after surgery for primary varicose veins. The aim of the present study was to evaluate the impact of preoperative duplex imaging after 7 years, in relation to other risk factors for varicose vein recurrence. Methods: Patients with primary varicose veins were randomized to operation with (group 1), or without (group 2) preoperative duplex imaging. The same patients were invited to attend follow-up with interview, clinical examination and duplex imaging. Quality of life (QoL) was measured with the Short Form 36 questionnaire. Results: Some 293 patients (343 legs) were included initially; after 7 years 227 were interviewed, or their records reviewed: 114 in group 1 and 113 in group 2. One hundred and ninety-four legs (95 in group 1 and 99 in group 2) were examined clinically and with duplex imaging. Incompetence was seen at the saphenofemoral junction and/or saphenopopliteal junction in 14 per cent of legs in group 1 and 46 per cent in group 2 (P < 0.001). QoL was similar in both groups. After a mean follow-up of 7 years (and including patients who underwent surgery after the review), 15 legs in group 1 needed reoperation and 38 in group 2 (P = 0.001). Conclusion: Routine preoperative duplex imaging improved the results of surgery for primary varicose veins for at least 7 years.
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| 9. |
- Brooks, Samantha J, et al.
(författare)
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Obsessive-compulsivity and working memory are associated with differential prefrontal cortex and insula activation in adolescents with a recent diagnosis of an eating disorder
- 2014
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Ingår i: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123 .- 0925-4927. ; 224:3, s. 246-253
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Tidskriftsartikel (refereegranskat)abstract
- The role of rumination at the beginning of eating disorder (ED) is not well understood. We hypothesised that impulsivity, rumination and restriction could be associated with neural activity in response to food stimuli in young individuals with eating disorders (ED). We measured neural responses with functional magnetic resonance imaging (fMRI), tested working memory (WM) and administered the eating disorders examination questionnaire (EDE-Q), Barratt impulsivity scale (BIS-11) and obsessive-compulsive inventory (OCI-R) in 15 adolescent females with eating disorder not otherwise specified (EDNOS) (mean age 15 years) and 20 age-matched healthy control females. We found that EDNOS subjects had significantly higher scores on the BIS 11, EDE-Q and OCI-R scales. Significantly increased neural responses to food images in the EDNOS group were observed in the prefrontal circuitry. OCI-R scores in the EDNOS group also significantly correlated with activity in the prefrontal circuitry and the cerebellum. Significantly slower WM responses negatively correlated with bilateral superior frontal gyrus activity in the EDNOS group. We conclude that ruminations, linked to WM, are present in adolescent females newly diagnosed with EDNOS. These may be risk factors for the development of an eating disorder and may be detectable before disease onset.
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- Ellery, W. N., et al.
(författare)
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Peat formation in the context of the development of the Mkuze floodplain on the coastal plain of Maputaland, South Africa
- 2012
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Ingår i: Geomorphology. - : Elsevier BV. - 0169-555X .- 1872-695X. ; 141, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the geomorphological and sedimentological development of blocked-valley lakes in the Mkuze floodplain on the coastal plain of Maputaland, northern KwaZulu-Natal, South Africa. Blocked tributary valley lakes north of the floodplain become progressively shorter, broader, and less linear toward the eastern (downstream) end of the east-west oriented Mkuze floodplain. Clastic sediment forms surface sedimentary fill in tributary valleys in the west, while peat predominates tributary valley fill in the east. Two contrasting adjacent tributary valleys were examined, the more western Yengweni dominated by clastic sediment at the surface, and the more eastern Totweni with peat. The Mkuze floodplain is characterised by silt with a low organic content. Surface sediments fine downstream and with distance from the main channel. Tributary sediment south of the lakes (adjacent to the floodplain) contains little organic material at the surface, but increases with depth. North (upstream) of Yengweni lake, the tributary valley contains peat up to 1.5 m thick, with organic contents up to 30% (generally 10 to 20%). In contrast, north (upstream) of Mpanza lake, peat up to 7 m thick is extensive with high organic contents (typically >60% at the surface but decreasing with depth). The thickness and width of the peat deposits increase longitudinally from the head of the tributary valley toward Mpanza lake. The distribution of clastic and organic sediments illustrates that as aggradation of the Mkuze floodplain progresses, tributary valleys initially fill with sediment from the local tributary catchment, lakes form, there is a phase of peat formation and finally, peat is buried by sediment from the Mkuze floodplain. We hypothesise that peat formation in subtropical and tropical settings through these processes is likely to be an important long-term sink for carbon.
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