81 resultados para AMS(14)C dating


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BACKGROUND: Hepatic steatosis may promote progression of chronic hepatitis C (CHC). Microsomal triglyceride transfer protein (MTP) is required for assembly and secretion of ApoB lipoprotein and is implicated in hepatitis C virus (HCV)-related steatosis. The MTP -493G/T polymorphism may promote liver fat accumulation, but its role in HCV-related steatosis is still unclear. METHODS: Two hundred ninety-eight CHC patients were studied and genotyped for MTP -493G/T variants. Hepatic MTP mRNA expression and activity were determined in a subgroup. RESULTS: Patients with grades 2/3 steatosis were older, had a higher body mass index (BMI), more advanced fibrosis and lower MTP mRNA expression and carried more often HCV genotype 3 and the MTP T allele. Age, BMI, HCV-3 and MTP T allele [odds ratio (OR) 2.05; 95% confidence interval (CI) 1.2-3.53; P=0.009] were independent risk factors for steatosis grades 2/3, and in HCV genotype non-3 patients, the MTP T allele was the strongest predictor for steatosis grade 2/3 (OR 2.17; 95% CI 1.22-3.86; P=0.008). Moreover, TT carriers had higher high-density lipoprotein (65.6+/-14.6 vs 56.1+/-16.2 mg/dl; P=0.003) and apolipoprotein AI (1.80+/-0.3 vs 1.60+/-0.3 g/L; P=0.005) levels than G allele carriers. CONCLUSIONS: Chronic hepatitis C patients with the MTP -493T allele reveal higher grades of steatosis, indicating a relevant contribution to liver fat accumulation, particularly in HCV non-3 patients.

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BACKGROUND: The aim of this study was to evaluate the effect of CD4+ T-cell counts and other characteristics of HIV-infected individuals on hepatitis C virus (HCV) RNA levels. METHODS: All HIV-HCV-coinfected Swiss HIV Cohort Study participants with available HCV RNA levels and concurrent CD4+ T-cell counts before starting HCV therapy were included. Potential predictors of HCV RNA levels were assessed by multivariate censored linear regression models that adjust for censored values. RESULTS: The study included 1,031 individuals. Low current and nadir CD4+ T-cell counts were significantly associated with higher HCV RNA levels (P = 0.004 and 0.001, respectively). In individuals with current CD4+ T-cell counts < 200/microl, median HCV RNA levels (6.22 log10 IU/ml) were +0.14 and +0.24 log10 IU/ml higher than those with CD4+ T-cell counts of 200-500/microl and > 500/microl. Based on nadir CD4+ T-cell counts, median HCV RNA levels (6.12 log10 IU/ml) in individuals with < 200/microl CD4+ T-cells were +0.06 and +0.44 log10 IU/ml higher than those with nadir T-cell counts of 200-500/microl and > 500/microl. Median HCV RNA levels were also significantly associated with HCV genotype: lower values were associated with genotype 4 and higher values with genotype 2, as compared with genotype 1. Additional significant predictors of lower HCV RNA levels were female gender and HIV transmission through male homosexual contacts. In multivariate analyses, only CD4+ T-cell counts and HCV genotype remained significant predictors of HCV RNA levels. Conclusions: Higher HCV RNA levels were associated with CD4+ T-cell depletion. This finding is in line with the crucial role of CD4+ T-cells in the control of HCV infection.

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We investigated oxygen and carbon isotopes of bulk carbonate and of benthic freshwater ostracods (Candona candida) in a sediment core of Lago Piccolo di Avigliana that was previously analyzed for pollen and loss-on-ignition, in order to reconstruct environmental changes during the late glacial and early Holocene. The depth-age relationship of the sediment core was established using 14 AMS C-14 dates and the Laacher See Tephra. While stable isotopes of bulk carbonates may have been affected by detrital input and, therefore, only indirectly reflect climatic changes, isotopes measured on ostracod shells provide unambiguous evidence for major environmental changes. Oxygen isotope ratios of ostracod shells (delta O-18(C)) increased by similar to 6 parts per thousand at the onset of the Bolling (similar to 14,650 cal BP) and were similar to 2 parts per thousand lower during the Younger Dryas (similar to 12,850 to 11,650 cal BP), indicating a temporal pattern of climate changes similar to the North Atlantic region. However, in contrast to records in that region, delta O-18(C) gradually decreased during the early Holocene, suggesting that compared to the Younger Dryas more humid conditions occurred and that the lake received gradually increasing input of O-18-depleted groundwater or river water.

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The many different proxy records from the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core allow for the first time a comparison of nine glacial terminations in great detail. Despite the fact that all terminations cover the transition from a glacial maximum into an interglacial, there are large differences between single terminations. For some terminations, Antarctic temperature increased only moderately, while for others, the amplitude of change at the termination was much larger. For the different terminations, the rate of change in temperature is more similar than the magnitude or duration of change. These temperature changes were accompanied by vast changes in dust and sea salt deposition all over Antarctica. Here we investigate the phasing between a South American dust proxy (non-sea-salt calcium flux, nssCa2+), a sea ice proxy (sea salt sodium flux, ssNa+) and a proxy for Antarctic temperature (deuterium, δD). In particular, we look into whether a similar sequence of events applies to all terminations, despite their different characteristics. All proxies are derived from the EPICA Dome C ice core, resulting in a relative dating uncertainty between the proxies of less than 20 years. At the start of the terminations, the temperature (δD) increase and dust (nssCa2+ flux) decrease start synchronously. The sea ice proxy (ssNa+ flux), however, only changes once the temperature has reached a particular threshold, approximately 5°C below present day temperatures (corresponding to a δD value of −420‰). This reflects to a large extent the limited sensitivity of the sea ice proxy during very cold periods with large sea ice extent. At terminations where this threshold is not reached (TVI, TVIII), ssNa+ flux shows no changes. Above this threshold, the sea ice proxy is closely coupled to the Antarctic temperature, and interglacial levels are reached at the same time for both ssNa+ and δD. On the other hand, once another threshold at approximately 2°C below present day temperature is passed (corresponding to a δD value of −402‰), nssCa2+ flux has reached interglacial levels and does not change any more, despite further warming. This threshold behaviour most likely results from a combination of changes to the threshold friction velocity for dust entrainment and to the distribution of surface wind speeds in the dust source region.

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Five cases of fatal babesiosis in free-ranging chamois (Rupicapra r. rupicapra) attributed to infections with Babesia capreoli were recently recorded in two regions of the Swiss Alps. To investigate the ecologic factors that possibly lead to those fatal B. capreoli infections in chamois, blood, ticks, and demographic data of 46 roe deer (Capreolus c. capreolus), 48 chamois, and nine red deer (Cervus elaphus) were collected in 2006 and 2007 in both affected regions. Whereas no parasitic inclusions were found by microscopical examination of blood smears, B. capreoli was identified by polymerase chain reaction/sequencing in blood of 12 roe deer (26%, 95% confidence interval [CI]: 14.3-41.1), one chamois (2%, CI: 0-6.1), and one red deer (11%, CI: 0.3-48.2). Prevalence of B. capreoli was significantly higher in roe deer compared with chamois (P<0.001). All 214 ticks were identified as Ixodes ricinus, and significantly more roe deer (63%, CI: 47.5-76.8) were infested compared with chamois (21%, CI: 10.5-35.0, P<0.001). Overall, prevalences of both tick infestation and Babesia infection increased significantly (P<0.001) with decreasing altitude, and Babesia-positive samples were detected significantly more often from animals with tick infestation compared with animals without ticks (P = 0.040). Our results indicate that roe deer may play an important reservoir role for B. capreoli. It is hypothesized that the expansion of the presumed vector I. ricinus to higher elevations and its increased abundance in overlapping habitats of roe deer and chamois may favor the spillover of B. capreoli from roe deer to chamois.

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Lake sediments from Lauenensee (1381 m a.s.l.), a small lake in the Bernese Alps, were analysed to reconstruct the vegetation and fire history. The chronology is based on 11 calibrated radiocarbon dates on terrestrial plant macrofossils suggesting a basal age of 14,200 cal. BP. Pollen and macrofossil data imply that treeline never reached the lake catchment during the Bølling–Allerød interstadial. Treeline north of the Alps was depressed by c. 300 altitudinal meters, if compared with southern locations. We attribute this difference to colder temperatures and to unbuffered cold air excursions from the ice masses in northern Europe. Afforestation started after the Younger Dryas at 11,600 cal. BP. Early-Holocene tree-Betula and Pinus sylvestris forests were replaced by Abies alba forests around 7500 cal. BP. Continuous high-resolution pollen and macrofossil series allow quantitative assessments of vegetation dynamics at 5900–5200 cal. BP (first expansion of Picea abies, decline of Abies alba) and 4100–2900 cal. BP (first collapse of Abies alba). The first signs of human activity became noticeable during the late Neolithic c. 5700–5200 cal. BP. Cross-correlation analysis shows that the expansion of Alnus viridis and the replacement of Abies alba by Picea abies after c. 5500 cal. BP was most likely a consequence of human disturbance. Abies alba responded very sensitively to a combination of fire and grazing disturbance. Our results imply that the current dominance of Picea abies in the upper montane and subalpine belts is a consequence of anthropogenic activities through the millennia.

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Anhand fossiler Überreste von Chironomiden (Zuckmücken) in den Sedimenten des Lauenensees wurden Temperaturveränderungen im westlichen Berner Oberland über die letzten 14 000 Jahre rekonstruiert. Mittlere Juli-Lufttemperaturen wurden mithilfe eines Kalibrationsdatensatzes und eines Temperaturrekonstruktionsmodells rekonstruiert, welches bereits in einer früheren Studie entwickelt worden ist. Während dem Allerød (~14,000-12,700 kal. Jahre vor heute) wurden Temperaturen zwischen 8,7-12,0 °C berechnet, während der Jüngeren Dryaszeit (-12 700- 11 700 kal. Jahre vor heute) Werte um 10,2-10,7 °C und während dem Früh- bis Mittelholozän (-11 700-3000 kal. Jahre vor heute) Temperaturen um 12,0-14,5 °C. Für das Spätholozän (ab -3000 kal. Jahre vor heute) wurden tiefere Temperaturen (10-12 °C) geschätzt. Der menschliche Einfluss wird ab 4300 kal. Jahre vor heute deutlich in den Chironomidenvergesellschaftungen sichtbar und beeinträchtigt möglicherweise die Verlässlichkeit der Temperaturrekonstruktion für dieses Zeitintervall. Die Temperaturrekonstruktion stimmt gut mit anderen paläoklimatischen Rekonstruktionen der Alpen sowie dem Anstieg der Baumgrenze in dieser Region überein.

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BACKGROUND Recommendations from international task forces on geriatric assessment emphasize the need for research including validation of cancer-specific geriatric assessment (C-SGA) tools in oncological settings. The objective of this study was to evaluate the feasibility of the SAKK Cancer-Specific Geriatric Assessment (C-SGA) in clinical practice. METHODS A cross sectional study of cancer patients >=65 years old (N = 51) with pathologically confirmed cancer presenting for initiation of chemotherapy treatment (07/01/2009-03/31/2011) at two oncology departments in Swiss canton hospitals: Kantonsspital Graubunden (KSGR N = 25), Kantonsspital St. Gallen (KSSG N = 26). Data was collected using three instruments, the SAKK C-SGA plus physician and patient evaluation forms. The SAKK C-SGA includes six measures covering five geriatric assessment domains (comorbidity, function, psychosocial, nutrition, cognition) using a mix of medical record abstraction (MRA) and patient interview. Five individual domains and one overall SAKK C-SGA score were calculated and dichotomized as below/above literature-based cut-offs. The SAKK C-SGA was evaluated by: patient and physician estimated time to complete, ease of completing, and difficult or unanswered questions. RESULTS Time to complete the patient questionnaire was considered acceptable by almost all (>=96%) patients and physicians. Patients reported slightly shorter times to complete the questionnaire than physicians (17.33 +/- 7.34 vs. 20.59 +/- 6.53 minutes, p = 0.02). Both groups rated the patient questionnaire as easy/fairly easy to complete (91% vs. 84% respectively, p = 0.14) with few difficult or unanswered questions. The MRA took on average 8.32 +/- 4.72 minutes to complete. Physicians (100%) considered time to complete MRA acceptable, 96% rated it as easy/fairly easy to complete. Individual study site populations differed on health-related characteristics (excellent/good physician-rated general health KSGR 71% vs. KSSG 32%, p = 0.007). The overall mean C-SGA score was 2.4 +/- 1.12. Patients at KSGR had lower C-SGA scores (2.00 +/- 1.19 vs. 2.81 +/- 0.90, p = 0.009) and a smaller proportion (28% vs.65%, p = 0.008) was above the C-SGA cut-off score compared to KSSG. CONCLUSIONS These results suggest the SAKK C-SGA is a feasible practical tool for use in clinical practice. It demonstrated discriminative ability based on objective geriatric assessment measures, but additional investigations on use for clinical decision-making are warranted. The SAKK C-SGA also provides important usable domain information for intervention to optimize outcomes in older cancer patients.

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High-resolution multiproxy analyses were performed on a 128 cm section of organic sediments accumulated in a small mountain lake in NW Iberia (Laguna de la Roya, 1608 m asl). The pollen stratigraphy together with radiocarbon dating provided the basis for a chronology ranging from 15,600 to 10,500 cal yr BP. Chironomid-inferred July air temperatures suggest a temperature range from 7 to 13 degrees C, also evidencing two well-established cold periods which may be equivalent to the INTIMATE stages GS-2a and GS-1. Furthermore, a number of short cold events (with summer temperatures dropping about 0.5-1 degrees C) appear intercalated within the Lateglacial Interstadial (possibly equivalent to the INTIMATE cold events GI-1d, GI-1c2 and GI-1b) and the early Holocene (possibly equivalent to the 11.2 k event). The temperature variations predicted by our reconstruction allow explaining the changes in local conditions and productivity of the lake inferred from the biological record of the same sediment core. Furthermore, they also agree with the local and regional vegetation dynamics, and the main oscillations deduced for the vegetation belts. Based on its chronology our multiproxy record indicates a similar temperature development in NW Iberia as inferred by the Greenland delta O-18 record, the marine deep-sea records off the Atlantic Iberian Margin, and other chironomid-based Lateglacial temperature reconstructions from Europe. Nevertheless, the impact of most of the less intense Lateglacial/early Holocene cold events in NW Iberia was most probably limited to very sensitive sites that were very close to ecotonal situations. Particularly, our new pollen record indicates that they were represented as three minor environmental crises occurring during the Lateglacial Interestadial in this area. The Older Dryas event (in our usage corresponding to the Aegelsee Oscillation in Central Europe and event GI-1d in central Greenland) has previously been described in this region, but its age and duration (ca 14,250-14050 cal yr BP) is now better constrained. The two subsequent stages, La Roya I (ca 13,600-13,400 cal yr BP) and La Roya II (ca 13,300-12,900 cal yr BP) have been described for first time in NW Iberia. (C) 2013 Elsevier Ltd. All rights reserved.

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Diepkloof Rock Shelter offers an exceptional opportunity to study the onset and evolution of both Still Bay (SB) and Howiesons Poort (HP) techno-complexes. However, previous age estimates based on luminescence dating of burnt quartzites (Tribolo et al., 2009) and of sediments (Jacobs et al., 2008) were not in agreement. Here, we present new luminescence ages for 17 rock samples (equivalent dose estimated with a SAR-ITL protocol instead of classical MAAD-TL) as well as for 5 sediment samples (equivalent dose estimated with SAR-single grain OSL protocol) and an update of the 22 previous age estimates for burnt lithics (modified calibration and beta dose estimates). While a good agreement between the rock and sediment ages is obtained, these estimates are still significantly older than those reported by Jacobs et al. (2008). After our own analyses of the sediment from Diepkloof, it is suspected that these authors did not correctly chose the parameters for the equivalent dose determination, leading to an underestimate of the equivalent doses, and thus of the ages. From bottom to top, the mean ages are 100 ± 10 ka for stratigraphic unit (SU) Noël and 107 ± 11 ka for SU Mark (uncharacterized Lower MSA), 100 ± 10 ka for SU Lynn-Leo (Pre-SB type Lynn), 109 ± 10 ka for SUs Kim-Larry (SB), 105 ± 10 ka for SUs Kerry-Kate and 109 ± 10 ka for SU Jess (Early HP), 89 ± 8 ka for SU Jude (MSA type Jack), 77 ± 8 ka for SU John, 85 ± 9 ka for SU Fox, 83 ± 8 ka for SU Fred and 65 ± 8 ka for SU OB5 (Intermediate HP), 52 ± 5 ka for SUs OB2-4 (Late HP). This chronology, together with the technological analyses, greatly modifies the current chrono-cultural model regarding the SB and the HP and has important archaeological implications. Indeed, SB and HP no longer appear as short-lived techno-complexes with synchronous appearances for each and restricted to Oxygen Isotopic Stage (OIS) 4 across South Africa, as suggested by Jacobs et al. (2008, 2012). Rather, the sequence of Diepkloof supports a long chronology model with an early appearance of both SB and HP in the first half of OIS 5 and a long duration of the HP into OIS 3. These new dates imply that different technological traditions coexisted during OIS 5 and 4 in southern Africa and that SB and HP can no longer be considered as horizon markers.

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Rigid electron donor-acceptor conjugates (1-3) that combine -extended benzodifurans as electron donors and C-60 molecules as electron acceptors with different linkers have been synthesized and investigated with respect to intramolecular charge-transfer events. Electrochemistry, fluorescence, and transient absorption measurements revealed tunable and structure-dependent charge-transfer processes in the ground and excited states. Our experimental findings are underpinned by density-functional theory calculations.