548 research outputs found

    Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125–97 ka): insights from a Belgian speleothem

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    The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and  ∼  97 ka, with interruptions of growth occurring at 117.3–112.9 and 106.6–103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e–5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite morphology, evidencing increased variability compared to the Eemian. Stadials that appear to be analogous to those in Greenland are recognized in Han-9, and the chronology is consistent with other European (speleothem) records. Greenland Stadial 25 is reflected as a cold/dry period within Han-9 stable isotope proxies, and the second interruption in speleothem growth occurs simultaneously with Greenland Stadial 24

    Reconstruction of MIS 5 climate in the central Levant using a stalagmite from Kanaan Cave, Lebanon

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    Lying at the transition between the temperate Mediterranean domain and subtropical deserts, the Levant is a key area to study the palaeoclimatic response over glacial–interglacial cycles. This paper presents a precisely dated last interglacial (MIS 5) stalagmite (129–84 ka) from the Kanaan Cave, Lebanon. Variations in growth rate and isotopic records indicate a warm humid phase at the onset of the last interglacial at ~ 129 ka that lasted until ~ 125 ka. A gradual shift in speleothem isotopic composition (125–122 ka) is driven mainly by the δ18O source effect of the eastern Mediterranean surface waters during sapropel 5 (S5). The onset of glacial inception began after ~ 122 ka, interrupted by a short wet pulse during the sapropel 4 (S4) event. Low growth rates and enriched oxygen and carbon values until ~ 84 ka indicate a transition to drier conditions during Northern Hemisphere glaciation

    Comparative anatomy of intervessel pits in two mangrove species growing along a natural salinity gradient in Gazi Bay, Kenya

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    Background and Aims: According to the air-seeding hypothesis, embolism vulnerability in xylem elements is linked directly to bordered pit structure and functioning. To elucidate the adaptive potential of intervessel pits towards fluctuating environmental conditions, two mangrove species with a distinct ecological distribution growing along a natural salinity gradient were investigated. Methods: Scanning and transmission electron microscopic observations were conducted to obtain qualitative and quantitative characteristics of alternate intervessel pits in A. marina and scalariform intervessel pits in Rhizophora mucronata. Wood samples from three to six trees were collected at seven and five sites for A. marina and R. mucronata, respectively, with considerable differences between sites in soil water salinity. Key Results: Vestured pits without visible pores in the pit membrane were observed in A. marina, the mangrove species with the widest geographical distribution on global as well as local scale. Their thick pit membranes (on average 370 nm) and minute pit apertures may contribute to reduced vulnerability to cavitation of this highly salt-tolerant species. The smaller ecological distribution of R. mucronata was in accordance with wide pit apertures and a slightly higher pitfield fraction (67 % vs. 60 % in A. marina). Nonetheless, its outer pit apertures were observed to be funnel-shaped shielding non-porous pit membranes. No trends in intervessel pit size were observed with increasing soil water salinity of the site. Conclusions: The contrasting ecological distribution of two mangrove species was reflected in the geometry and pit membrane characteristics of their intervessel pits. Within species, intervessel pit size seemed to be independent of spatial variations in environmental conditions and was only weakly correlated with vessel diameter. Further research on pit formation and function has to clarify the large variations in intervessel pit size within trees and even within single vessels

    Consensus-Based Core Set of Outcome Measures for Clinical Motor Rehabilitation After Stroke—A Delphi Study

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    Introduction: Outcome measures are key to tailor rehabilitation goals to the stroke patient's individual needs and to monitor poststroke recovery. The large number of available outcome measures leads to high variability in clinical use. Currently, an internationally agreed core set of motor outcome measures for clinical application is lacking. Therefore, the goal was to develop such a set to serve as a quality standard in clinical motor rehabilitation poststroke. / Methods: Outcome measures for the upper and lower extremities, and activities of daily living (ADL)/stroke-specific outcomes were identified and presented to stroke rehabilitation experts in an electronic Delphi study. In round 1, clinical feasibility and relevance of the outcome measures were rated on a 7-point Likert scale. In round 2, those rated at least as “relevant” and “feasible” were ranked within the body functions, activities, and participation domains of the International Classification of Functioning, Disability, and Health (ICF). Furthermore, measurement time points poststroke were indicated. In round 3, answers were reviewed in reference to overall results to reach final consensus. / Results: In total, 119 outcome measures were presented to 33 experts from 18 countries. The recommended core set includes the Fugl–Meyer Motor Assessment and Action Research Arm Test for the upper extremity section; the Fugl–Meyer Motor Assessment, 10-m Walk Test, Timed-Up-and-Go, and Berg Balance Scale for the lower extremity section; and the National Institutes of Health Stroke Scale, and Barthel Index or Functional Independence Measure for the ADL/stroke-specific section. The Stroke Impact Scale was recommended spanning all ICF domains. Recommended measurement time points are days 2 ± 1 and 7; weeks 2, 4, and 12; 6 months poststroke and every following 6th month. / Discussion and Conclusion: Agreement was found upon a set of nine outcome measures for application in clinical motor rehabilitation poststroke, with seven measurement time points following the stages of poststroke recovery. This core set was specifically developed for clinical practice and distinguishes itself from initiatives for stroke rehabilitation research. The next challenge is to implement this clinical core set across the full stroke care continuum with the aim to improve the transparency, comparability, and quality of stroke rehabilitation at a regional, national, and international level

    Donor KIR B Genotype Improves Progression-Free Survival of Non-Hodgkin Lymphoma Patients Receiving Unrelated Donor Transplantation

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    Donor killer immunoglobulin-like receptor (KIR) genotypes are associated with relapse protection and survival after allotransplantation for acute myelogenous leukemia. We examined the possibility of a similar effect in a cohort of 614 non-Hodgkin lymphoma (NHL) patients receiving unrelated donor (URD) T cell-replete marrow or peripheral blood grafts. Sixty-four percent (n = 396) of donor-recipient pairs were 10/10 allele HLA matched and 26% were 9/10 allele matched. Seventy percent of donors had KIR B/x genotype; the others had KIR A/A genotype. NHL patients receiving 10/10 HLA-matched URD grafts with KIR B/x donors experienced significantly lower relapse at 5 years (26%; 95% confidence interval [CI], 21% to 32% versus 37%; 95% CI, 27% to 46%; P = .05) compared with KIR A/A donors, resulting in improved 5-year progression-free survival (PFS) (35%; 95% CI, 26% to 44% versus 22%; 95% CI, 11% to 35%; P = .007). In multivariate analysis, use of KIR B/x donors was associated with significantly reduced relapse risk (relative risk [RR], .63, P = .02) and improved PFS (RR, .71, P = .008). The relapse protection afforded by KIR B/x donors was not observed in HLA-mismatched transplantations and was not specific to any particular KIR-B gene. Selecting 10/10 HLA-matched and KIR B/x donors should benefit patients with NHL receiving URD allogeneic transplantation

    Testing the theory of immune selection in cancers that break the rules of transplantation

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    Modification of cancer cells likely to reduce their immunogenicity, including loss or down-regulation of MHC molecules, is now well documented and has become the main support for the concept of immune surveillance. The evidence that these modifications, in fact, result from selection by the immune system is less clear, since the possibility that they may result from reorganized metabolism associated with proliferation or from cell de-differentiation remains. Here, we (a) survey old and new transplantation experiments that test the possibility of selection and (b) survey how transmissible tumours of dogs and Tasmanian devils provide naturally evolved tests of immune surveillance

    Measurement of motor-evoked potential resting threshold and amplitude of proximal and distal arm muscles in healthy adults. A reliability study

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    Purpose: Reliability of motor-evoked potential threshold and amplitude measurement of upper limb muscles is important when detecting changes in cortical excitability. The objective of this study was to investigate intra-rater, test-retest reliability and minimal detectable change of resting motor threshold and amplitude of a proximal and distal upper limb muscles, anterior deltoid and distal extensor digitorum communis in healthy adults. Method: To measure motor-evoked potential responses, transcranial magnetic stimulation was interfaced with electromyography and neuronavigation equipment. Two measurements were conducted on day 1 and a third measurement three days later. Reliability was analysed using intraclass correlation coefficients. Results: Twenty participants completed the study. Excellent intra-rater (intraclass correlation coefficient = 0.91 (extensor digitorum), 0.94 (anterior deltoid)) and good to excellent test-retest reliability (intraclass correlation coefficient = 0.69 (anterior deltoid), 0.84 (extensor digitorum)) was found for resting motor threshold. Minimal detectable change for resting motor threshold was found at 10.95% (extensor digitorum) and 16.35% (anterior deltoid) between first and third measurements. Motor-evoked potential amplitude of extensor digitorum communis had fair to good intra-rater (intraclass correlation coefficient = 0.50) and test-retest reliability (intraclass correlation coefficient = 0.65). Conclusions: Our results suggest that resting motor threshold is a reliable neurophysiological measure even for proximal shoulder muscles. Future research should further explore the reliability of motor-evoked potential amplitude before integration into neurological rehabilitation

    Low CD4+ T Cell Counts among African HIV-1 Infected Subjects with Group B KIR Haplotypes in the Absence of Specific Inhibitory KIR Ligands

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    Natural killer (NK) cells are regulated by interactions between polymorphic killer immunoglobulin-like receptors (KIR) and human leukocyte antigens (HLA). Genotypic combinations of KIR3DS1/L1 and HLA Bw4-80I were previously shown to influence HIV-1 disease progression, however other KIR genes have not been well studied. In this study, we analyzed the influence of all activating and inhibitory KIR, in association with the known HLA inhibitory KIR ligands, on markers of disease progression in a West African population of therapy-naïve HIV-1 infected subjects. We observed a significant association between carriage of a group B KIR haplotype and lower CD4+ T cell counts, with an additional effect for KIR3DS1 within the frame of this haplotype. In contrast, we found that individuals carrying genes for the inhibitory KIR ligands HLA-Bw4 as well as HLA-C1 showed significantly higher CD4+ T cell counts. These associations were independent from the viral load and from individual HIV-1 protective HLA alleles. Our data suggest that group B KIR haplotypes and lack of specific inhibitory KIR ligand genes, genotypes considered to favor NK cell activation, are predictive of HIV-1 disease progression
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