978 resultados para Van Inwagen, James W.
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Shallow ice cores were obtained from widely distributed sites across the West Antarctic ice sheet, as part of the United States portion of the International Trans-Antarctic Scientific Expedition (US ITASE) program. The US ITASE cores have been dated by annual-layer counting, primarily through the identification of summer peaks in non-sea-salt sulfate (nssSO(4)(2-)) concentration. Absolute dating accuracy of better than 2 years and relative dating accuracy better than 1 year is demonstrated by the identification of multiple volcanic marker horizons in each of the cores, Tambora, Indonesia (1815), being the most prominent. Independent validation is provided by the tracing of isochronal layers from site to site using high-frequency ice-penetrating radar observations, and by the timing of mid-winter warming events in stable-isotope ratios, which demonstrate significantly better than 1 year accuracy in the last 20 years. Dating precision to 1 month is demonstrated by the occurrence of summer nitrate peaks and stable-isotope ratios in phase with nssSO(4)(2-), and winter-time sea-salt peaks out of phase, with phase variation of < 1 month. Dating precision and accuracy are uniform with depth, for at least the last 100 years.
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The transition from the Oldest Dryas to the Bølling around 14,685 cal yr BP was a period of extremely rapid climatic warming. From a single core of lake marl taken at Gerzensee (Switzerland) we studied the transition in stable isotopes of oxygen and carbon on bulk sediment and charophyte remains, as well as on monospecific samples of ostracods, after Pisidium a; in addition pollen, chironomids, and Cladocera were analyzed. The δ18O record serves as an estimate of mean air temperature, and by correlation to the one from NGRIP in Greenland it provides a timescale. The timing of responses: The statistically significant zone boundaries of the biostratigraphies are telescoped at the rapid increase of about 3‰ in δ18O at the onset of Bølling. Biotic responses may have occurred within sampling resolution (8 to 16 years), although younger zone boundaries are less synchronous. Gradual and longer-lasting responses include complex processes such as primary or secular succession. During the late-glacial interstadial of Bølling and Allerød, two stronger and two weaker cool phases were found. Biological processes involved in the responses occurred on levels of individuals (e.g. pollen productivity), of populations (increases or decreases, immigration, or extinction), and on the ecosystem level (species interactions such as facilitation or competition). Abiotic and biotic interactions include pedogenesis, nitrogen-fixation, nutrient cycling, catchment hydrology, water chemistry of the lake and albedo (controlled by the transition from tundra to forest). For the Swiss Plateau this major change in vegetation induced a change in the mammal fauna, which in turn led to changes in the tool-making by Paleolithic people.
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Sub-fossil Cladocera were studied in a core from Gerzensee (Swiss Plateau) for the late-glacial periods of Oldest Dryas, Bølling, and Allerød. Cladocera assemblages were dominated by cold-tolerant littoral taxa Chydorus sphaericus, Acroperus harpae, Alonella nana, Alona affinis, and Alonella excisa. The rapid warming at the beginning of the Bølling (GI-1e) ca. 14,650 yr before present (BP: before AD 1950) was indicated by an abrupt 2‰ shift in carbonate δ18O and a clear change in pollen assemblages. Cladocera assemblages, in contrast, changed more gradually. C. sphaericus and A. harpae are the most cold-tolerant, and their abundance was highest in the earliest part of the record. Only 150–200 years after the beginning of the Bølling warming we observed an increase in less cold-tolerant A. excisa and A. affinis. The establishment of Alona guttata, A. guttata var. tuberculata, and Pleuroxus unicatus was delayed by ca. 350, 770, and 800 years respectively after the onset of the Bølling. The development of the Cladocera assemblages suggests increasing water temperatures during the Bølling/Allerød, which agrees with the interpretation by von Grafenstein et al. (2013-this issue) that decreasing δ18O values in carbonates in this period reflect increasing summer water temperatures at the sediment–water interface. Other processes also affected the Cladocera community, including the development and diversification of aquatic vegetation favourable for Cladocera. The record is clearly dominated by Chydoridae, as expected for a littoral core. Yet, the planktonic Eubosmina-group occurred throughout the core, with the exception of a period at ca. 13,760–13,420 yr BP. Lake levels reconstructed for this period are relatively low, indicating that the littoral location might have become too shallow for Eubosmina in that period.
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We have measured the CO2 concentration of air occluded during the last 40,000 years in the deep Siple Dome A ( hereafter Siple Dome) ice core, Antarctica. The general trend of CO2 concentration from Siple Dome ice follows the temperature inferred from the isotopic composition of the ice and is mostly in agreement with other Antarctic ice core CO2 records. CO2 rose initially at similar to 17.5 kyr B. P. ( thousand years before 1950), decreased slowly during the Antarctic Cold Reversal, rose during the Younger Dryas, fell to a local minimum at around 8 kyr B. P., and rose continuously since then. The CO2 concentration never reached steady state during the Holocene, as also found in the Taylor Dome and EPICA Dome C ( hereafter Dome C) records. During the last glacial termination, a lag of CO2 versus Siple Dome isotopic temperature is probable. The Siple Dome CO2 concentrations during the last glacial termination and in the Holocene are at certain times greater than in other Antarctic ice cores by up to 20 ppm (mumol CO2/mol air). While in situ production of CO2 is one possible cause of the sporadic elevated levels, the mechanism leading to the enrichment is not yet clear.
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DNA-based parentage determination accelerates genetic improvement in sheep by increasing pedigree accuracy. Single nucleotide polymorphism (SNP) markers can be used for determining parentage and to provide unique molecular identifiers for tracing sheep products to their source. However, the utility of a particular "parentage SNP" varies by breed depending on its minor allele frequency (MAF) and its sequence context. Our aims were to identify parentage SNPs with exceptional qualities for use in globally diverse breeds and to develop a subset for use in North American sheep. Starting with genotypes from 2,915 sheep and 74 breed groups provided by the International Sheep Genomics Consortium (ISGC), we analyzed 47,693 autosomal SNPs by multiple criteria and selected 163 with desirable properties for parentage testing. On average, each of the 163 SNPs was highly informative (MAF≥0.3) in 48±5 breed groups. Nearby polymorphisms that could otherwise confound genetic testing were identified by whole genome and Sanger sequencing of 166 sheep from 54 breed groups. A genetic test with 109 of the 163 parentage SNPs was developed for matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The scoring rates and accuracies for these 109 SNPs were greater than 99% in a panel of North American sheep. In a blinded set of 96 families (sire, dam, and non-identical twin lambs), each parent of every lamb was identified without using the other parent's genotype. In 74 ISGC breed groups, the median estimates for probability of a coincidental match between two animals (PI), and the fraction of potential adults excluded from parentage (PE) were 1.1×10(-39) and 0.999987, respectively, for the 109 SNPs combined. The availability of a well-characterized set of 163 parentage SNPs facilitates the development of high-throughput genetic technologies for implementing accurate and economical parentage testing and traceability in many of the world's sheep breeds.
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BACKGROUND Dimethyl sulfoxide (DMSO) is essential for the preservation of liquid nitrogen-frozen stem cells, but is associated with toxicity in the transplant recipient. STUDY DESIGN AND METHODS In this prospective noninterventional study, we describe the use of DMSO in 64 European Blood and Marrow Transplant Group centers undertaking autologous transplantation on patients with myeloma and lymphoma and analyze side effects after return of DMSO-preserved stem cells. RESULTS While the majority of centers continue to use 10% DMSO, a significant proportion either use lower concentrations, mostly 5 or 7.5%, or wash cells before infusion (some for selected patients only). In contrast, the median dose of DMSO given (20 mL) was much less than the upper limit set by the same institutions (70 mL). In an accompanying statistical analysis of side effects noted after return of DMSO-preserved stem cells, we show that patients in the highest quartile receiving DMSO (mL and mL/kg body weight) had significantly more side effects attributed to DMSO, although this effect was not observed if DMSO was calculated as mL/min. Dividing the myeloma and lymphoma patients each into two equal groups by age we were able to confirm this result in all but young myeloma patients in whom an inversion of the odds ratio was seen, possibly related to the higher dose of melphalan received by young myeloma patients. CONCLUSION We suggest better standardization of preservation method with reduced DMSO concentration and attention to the dose of DMSO received by patients could help reduce the toxicity and morbidity of the transplant procedure.
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CONTEXT Although open radical cystectomy (ORC) is still the standard approach, laparoscopic radical cystectomy (LRC) and robot-assisted radical cystectomy (RARC) are increasingly performed. OBJECTIVE To report on a systematic literature review and cumulative analysis of pathologic, oncologic, and functional outcomes of RARC in comparison with ORC and LRC. EVIDENCE ACQUISITION Medline, Scopus, and Web of Science databases were searched using a free-text protocol including the terms robot-assisted radical cystectomy or da Vinci radical cystectomy or robot* radical cystectomy. RARC case series and studies comparing RARC with either ORC or LRC were collected. A cumulative analysis was conducted. EVIDENCE SYNTHESIS The searches retrieved 105 papers, 87 of which reported on pathologic, oncologic, or functional outcomes. Most series were retrospective and had small case numbers, short follow-up, and potential patient selection bias. The lymph node yield during lymph node dissection was 19 (range: 3-55), with half of the series following an extended template (yield range: 11-55). The lymph node-positive rate was 22%. The performance of lymphadenectomy was correlated with surgeon and institutional volume. Cumulative analyses showed no significant difference in lymph node yield between RARC and ORC. Positive surgical margin (PSM) rates were 5.6% (1-1.5% in pT2 disease and 0-25% in pT3 and higher disease). PSM rates did not appear to decrease with sequential case numbers. Cumulative analyses showed no significant difference in rates of surgical margins between RARC and ORC or RARC and LRC. Neoadjuvant chemotherapy use ranged from 0% to 31%, with adjuvant chemotherapy used in 4-29% of patients. Only six series reported a mean follow-up of >36 mo. Three-year disease-free survival (DFS), cancer-specific survival (CSS), and overall survival (OS) rates were 67-76%, 68-83%, and 61-80%, respectively. The 5-yr DFS, CSS, and OS rates were 53-74%, 66-80%, and 39-66%, respectively. Similar to ORC, disease of higher pathologic stage or evidence of lymph node involvement was associated with worse survival. Very limited data were available with respect to functional outcomes. The 12-mo continence rates with continent diversion were 83-100% in men for daytime continence and 66-76% for nighttime continence. In one series, potency was recovered in 63% of patients who were evaluable at 12 mo. CONCLUSIONS Oncologic and functional data from RARC remain immature, and longer-term prospective studies are needed. Cumulative analyses demonstrated that lymph node yields and PSM rates were similar between RARC and ORC. Conclusive long-term survival outcomes for RARC were limited, although oncologic outcomes up to 5 yr were similar to those reported for ORC. PATIENT SUMMARY Although open radical cystectomy (RC) is still regarded as the standard treatment for muscle-invasive bladder cancer, laparoscopic and robot-assisted RCs are becoming more popular. Templates of lymph node dissection, lymph node yields, and positive surgical margin rates are acceptable with robot-assisted RC. Although definitive comparisons with open RC with respect to oncologic or functional outcomes are lacking, early results appear comparable.
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by Arnold D. Margolin. Foreword by James W. Gerard
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REV3, the catalytic subunit of translesion polymerase zeta (polζ), is commonly associated with DNA damage bypass and repair. Despite sharing accessory subunits with replicative polymerase δ, very little is known about the role of polζ in DNA replication. We previously demonstrated that inhibition of REV3 expression induces persistent DNA damage and growth arrest in cancer cells. To reveal determinants of this sensitivity and obtain insights into the cellular function of REV3, we performed whole human genome RNAi library screens aimed at identification of synthetic lethal interactions with REV3 in A549 lung cancer cells. The top confirmed hit was RRM1, the large subunit of ribonucleotide reductase (RNR), a critical enzyme of de novo nucleotide synthesis. Treatment with the RNR-inhibitor hydroxyurea (HU) synergistically increased the fraction of REV3-deficient cells containing single stranded DNA (ssDNA) as indicated by an increase in replication protein A (RPA). However, this increase was not accompanied by accumulation of the DNA damage marker γH2AX suggesting a role of REV3 in counteracting HU-induced replication stress (RS). Consistent with a role of REV3 in DNA replication, increased RPA staining was confined to HU-treated S-phase cells. Additionally, we found genes related to RS to be significantly enriched among the top hits of the synthetic sickness/lethality (SSL) screen further corroborating the importance of REV3 for DNA replication under conditions of RS.
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Pollen-trap results from the Swiss Alps 1996–2009 were used to assess the pollen dispersal–deposition properties of Poaceae (grasses) and Cyperaceae (sedges). Dispersal parameter values were investigated for a modified version of the Prentice–Sugita pollen dispersal–deposition model. Appropriate values (i.e. realistic in the field and allowing realistic modelling results) for wind speed are suggested to be in the range of 3–7 m s− 1 and for pollen an injection height of 0.03–0.1 m above the ground. The appropriate range of pollen injection height values for grasses and sedges differs from that of trees in the same area, suggesting different pollen dispersal properties between herbs and trees. In addition, logarithmic weighting of the vegetation was tested as an alternative to the modified Prentice–Sugita model. This yielded very similar results, suggesting that the use of such much simpler approximations of the pollen–vegetation relationship is a plausible alternative. Based on the modified Prentice–Sugita model, absolute pollen productivity for Poaceae was estimated to 7300 ± 400 grains cm− 2 year− 1 (1 SE). The data basis for Cyperaceae is smaller than for Poaceae, but the dispersal parameter values determined as appropriate for Poaceae yield good results. Absolute pollen productivity for Cyperaceae was estimated to 6300 ± 1100 grains cm− 2 year− 1 (1 SE).
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[2: vervolgd op de 3 boeken van Petrus Cunaeus; 3: Grootdeels] Uyt de naargelaten [3: naagelaaten]. Schriften van H[ugo] W[illem] Goeree