袋装折叠式冰帽的设计及临床应用

适方便,临床降温效果好.     

超早期冰敷治疗重型颅脑损伤的疗效观察

[目的]探讨实施超早期冰敷治疗重型颅脑损伤的临床疗效。[方法]按入院先后顺序单双数将68例重型颅脑损伤病人分为观察组和对照组各34例,两组均行常规药物、手术、综合治疗。实验组实施超早期冰敷,对照组在38℃以上实施冰敷。[结果]观察组病人生命体征较对照组容易控制在正常范围(P<0.05),实验组预后明显优于对照组(P<0.01)。[结论]超早期冰敷能有效地控制重型颅脑损伤病人的体温,促进神经功能恢复,改善预后。     

超早期冰敷治疗重型颅脑损伤的疗效观察

[目的]探讨实施超早期冰敷治疗重型颅脑损伤的临床疗效.[方法]按入院先后顺序单双数将68例重型颅脑损伤病人分为观察组和对照组各34例,两组均行常规药物、手术、综合治疗.实验组实施超早期冰敷,对照组在38℃以上实施冰敷.[结果]观察组病人生命体征较对照组容易控制在正常范围(P＜0.05),实验组预后明显优于对照组(P＜0.01).[结论]超早期冰敷能有效地控制重型颅脑损伤病人的体温,促进神经功能恢复,改善预后.     

Mechanisms for low-frequency variability of summer Arctic sea ice extent

Satellite observations reveal a substantial decline in September Arctic sea ice extent since 1979, which has played a leading role in the observed recent Arctic surface warming and has often been attributed, in large part, to the increase in greenhouse gases. However, the most rapid decline occurred during the recent global warming hiatus period. Previous studies are often focused on a single mechanism for changes and variations of summer Arctic sea ice extent, and many are based on short observational records. The key players for summer Arctic sea ice extent variability at multidecadal/centennial time scales and their contributions to the observed summer Arctic sea ice decline are not well understood. Here a multiple regression model is developed for the first time, to the author’s knowledge, to provide a framework to quantify the contributions of three key predictors (Atlantic/Pacific heat transport into the Arctic, and Arctic Dipole) to the internal low-frequency variability of Summer Arctic sea ice extent, using a 3,600-y-long control climate model simulation. The results suggest that changes in these key predictors could have contributed substantially to the observed summer Arctic sea ice decline. If the ocean heat transport into the Arctic were to weaken in the near future due to internal variability, there might be a hiatus in the decline of September Arctic sea ice. The modeling results also suggest that at multidecadal/centennial time scales, variations in the atmosphere heat transport across the Arctic Circle are forced by anticorrelated variations in the Atlantic heat transport into the Arctic.Observations reveal multidecadal variations in Arctic surface air temperature (SAT), and amplified Arctic warming similar to that observed in recent decades also occurred during 1930–1940 (1–3). Both observations and climate modeling results suggest that the reduced Arctic sea ice is crucial for the early twentieth century Arctic warming, and internal variability is a very likely cause for that event (3). In recent decades, satellite observations reveal a substantial decline in September Arctic sea ice extent (4). This observed recent Arctic sea ice decline is also found to have played a leading role in causing the observed amplified Arctic surface warming in recent decades (5, 6).The summer Arctic was projected to become ice-free within a few decades by some climate models used in Coupled Model Intercomparison Project Phase 5 (CMIP5) due to the increase in anthropogenic greenhouse gases (7, 8), or even within the next decade if extrapolating the observed trend (9). These future projections imply enormous social and economic impacts, such as the potential for trans-Arctic shipping. However, the most rapid decline in summer Arctic sea ice actually occurred during the recent global warming hiatus period. The CMIP5 multimodel mean response to changes in anthropogenic radiative forcings exhibits much less decline in September Arctic sea ice extent (SIE) but stronger warming in global mean surface temperature than that observed over the recent hiatus period (10), implying that natural variability might have played an important role in the observed recent decline in September Arctic SIE.Various mechanisms have been proposed separately for the observed recent summer Arctic sea ice decline, such as the positive ice infrared feedback, i.e., enhanced downward longwave radiative flux due to increased air temperature, water vapor, cloudiness, and reduced sea ice (11, 12); the positive ice albedo feedback (13–15); the warming of the Atlantic water in the Arctic (16–18); the increase in Bering Strait ocean heat fluxes (19); the influence of wind forcing over the central Arctic associated with the Arctic Oscillation (AO) (20, 21) and the nonlinear positive feedback (22) among Pacific inflow, Beaufort Gyre (23), and AO at interannual time scale; and the interaction between the Arctic Dipole (AD) and transpolar ice drift (24–28). The previous studies are often based on short observational records. Some crucial questions remain unknown, e.g., what are the key players for internal variability of summer Arctic SIE at multidecadal/centennial time scales and how do they contribute to the observed summer Arctic SIE decline?Multidecadal internal variability has been observed in the Atlantic (29), and climate models suggest that the Atlantic Meridional Overturning Circulation (AMOC) variability is a major source for the Atlantic multidecadal variability (AMV) and might be important for the observed opposite trends in Arctic and Antarctica sea ice (30). Both modeling results (31, 32) and multicentury historical records (33) showed that winter Arctic sea ice variability is closely linked to the AMV. The AMOC is suggested to have strengthened since the mid 1970s as implied indirectly by its fingerprints (34, 35). Could a strengthened AMOC have led to an enhanced Atlantic heat transport into the Arctic and thus contributed to the observed recent summer Arctic SIE decline? If the AMOC and the associated Atlantic heat transport into the Arctic were to weaken in the near future due to internal variability, would there be a hiatus in the decline of September Arctic SIE and a delay in attaining a summer ice-free Arctic?Motivated by the above questions, this paper investigates the internal low-frequency variability of summer Arctic SIE, using a 3,600-y segment of a control simulation from a renowned climate model, Geophysical Fluid Dynamics Laboratory (GFDL) Coupled Model version 2.1 (CM2.1) (36). Three key predictors for internal low-frequency variability of summer Arctic SIE are identified, and they cover a broad range of internal variability in the climate system, including both the Atlantic and Pacific ocean heat transport into the Arctic, as well as the atmosphere circulation. A multiple regression model is developed to provide a framework to quantify the contributions of the three key predictors. The advantage of such a long control simulation is the statistical reliability, especially at multidecadal/centennial time scales, which cannot be obtained by short observational records. The estimated contributions of these key predictors to the observed summer Arctic SIE decline are also discussed.     

Life and extinction of megafauna in the ice-age Arctic

Understanding the population dynamics of megafauna that inhabited the mammoth steppe provides insights into the causes of extinctions during both the terminal Pleistocene and today. Our study area is Alaska''s North Slope, a place where humans were rare when these extinctions occurred. After developing a statistical approach to remove the age artifacts caused by radiocarbon calibration from a large series of dated megafaunal bones, we compare the temporal patterns of bone abundance with climate records. Megafaunal abundance tracked ice age climate, peaking during transitions from cold to warm periods. These results suggest that a defining characteristic of the mammoth steppe was its temporal instability and imply that regional extinctions followed by population reestablishment from distant refugia were characteristic features of ice-age biogeography at high latitudes. It follows that long-distance dispersal was crucial for the long-term persistence of megafaunal species living in the Arctic. Such dispersal was only possible when their rapidly shifting range lands were geographically interconnected. The end of the last ice age was fatally unique because the geographic ranges of arctic megafauna became permanently fragmented after stable, interglacial climate engendered the spread of peatlands at the same time that rising sea level severed former dispersal routes.One of the most intriguing examples of mass extinction and the most accessible in terms of its geological record occurred around the end of the Wisconsin ice age ca. 10–45 calendar ka B.P. (10,000–45,000 calendar y ago) when some 65% of terrestrial megafauna genera (animals weighing >45 kg) became globally extinct (1). Based on what we know about recent species extinctions, the causes of extinction are usually synergistic, often species-specific, and therefore, complex, which implies that there is no universal explanation for end-Pleistocene extinctions (2, 3). Globally and specifically in the Arctic (3–10), megafaunal extinctions have been variously blamed on overhunting, rapid climate change, habitat loss, and introduced diseases (3–10). Further complicating a clear understanding of the causes of ice-age extinctions is that the magnitude and tempo of environmental change during the last 100,000 y of the Pleistocene were fundamentally different than during the Holocene (11), and these differences had far-reaching implications for community structure, evolution, and extinction causes (12).A recent survey comparing the extinction dates of circumboreal megafauna with ice-age climate suggests that extinctions and genetic turnover were most frequent during warm, interstadial events (13). However, the mechanisms for these extinctions remain unclear, partly because this previous study considered multiple taxa living in many different ecosystems. Here, we focus on five megafaunal species that coinhabited a region of the Arctic with an ecological setting that is relatively well-understood. To avoid the methodological problems involved in pinpointing extinction dates (13), we infer population dynamics from changes in the relative abundance of megafauna over time. Using a uniquely large dataset of dated megafaunal bones from one particular area, we test a specific paleoecological hypothesis relating rapid climate change to population dynamics—namely, that transitions from cold to warm intervals were briefly optimal for grazing megafauna.The study area is Alaska’s North Slope, the tundra region bordered to the south by the Brooks Range and to the north by the Arctic Ocean (Fig. 1). The North Slope is a particularly interesting place to study end-Pleistocene extinctions for several reasons. First, its ice-age megafauna included iconic species like woolly mammoth (Mammuthus primigenius), steppe bison (Bison priscus), and cave lion (Panthera spelaea) (14). Second, the local extinctions of megafauna on Alaska’s North Slope occurred at a time when archaeological remains are rare, suggesting that people seldom ventured there (15, 16). Third, bone preservation in arctic environments tends to be excellent because of the presence of permafrost (perennially frozen ground), which makes it possible to ¹⁴C date large numbers of bones from many different species (SI Appendix, Table S1). Our record of dated bones provides key insights into the temporal dynamics and biogeographical characteristics of the mammoth steppe, a biome that was unique to the ice ages and the exact nature of which has been long debated (17).Open in a separate windowFig. 1.The North Slope is the tundra region between the Brooks Range and the Arctic Ocean. The light blue area shows the extent of the Bering Land Bridge during the last glacial maximum (LGM) ca. 19,000 calendar y B.P. Glacier extent (gray) during the LGM is based on the works by Dyke (64) and Brigham-Grette et al. (71). The timing of the opening of the ice-free corridor is still uncertain.     

Detection of viable Salmonella in ice cream by TaqMan real-time polymerase chain reaction assay combining propidium monoazide

Real-time polymerase chain reaction (PCR) allows rapid detection of Salmonella in frozen dairy products, but it might cause a false positive detection result because it might amplify DNA from dead target cells as well. In this study, Salmonella-free frozen ice cream was initially inoculated with heat-killed Salmonella Typhimurium cells and stored at −18°C. Bacterial DNA extracted from the sample was amplified using TaqMan probe-based real-time PCR targeting the invA gene. Our results indicated that DNA from the dead cells remained stable in frozen ice cream for at least 20 days, and could produce fluorescence signal for real-time PCR as well. To overcome this limitation, propidium monoazide (PMA) was combined with real-time PCR. PMA treatment can effectively prevent PCR amplification from heat-killed Salmonella cells in frozen ice cream. The PMA real-time PCR assay can selectively detect viable Salmonella at as low as 10³ CFU/mL. Combining 18 hours of pre-enrichment with the assay allows for the detection of viable Salmonella at 10⁰ CFU/mL and avoiding the false-positive result of dead cells. The PMA real-time PCR assay provides an alternative specifically for detection of viable Salmonella in ice cream. However, when the PMA real-time PCR assay was evaluated in ice cream subjected to frozen storage, it obviously underestimated the contamination situation of viable Salmonella, which might lead to a false negative result. According to this result, the use of enrichment prior to PMA real-time PCR analysis remains as the more appropriate approach.     

犬骨髓基质细胞复合nHAC/CSH裸鼠皮下成骨的实验研究

目的：评价纳米晶羟基磷灰石/胶原/硫酸钙(nHAC/CSH)—犬骨髓基质细胞(bone marrow stromal cells,BMSCs)复合物体内异位成骨能力。方法：犬骨髓基质细胞(dBMSCs)通过密度梯度离心法分离得到,与nHAC/CSH复合,构建可注射骨,扫描电镜观察细胞生长情况,并将构建的可注射组织工程骨植入裸鼠体内,4周后行HE染色观察异位骨形成情况。结果：扫描电镜观察细胞生长良好,体内研究表明,可注射组织工程骨植入裸鼠皮下4周后有类骨样结构形成。结论：nHAC/CSH复合BMSCs具有良好的成骨活性。     

Hepatocyte cryopreservation: Is it time to change the strategy?

Liver cell transplantation presents clinical benefit in patients with inborn errors of metabolism as an alternative,or at least as a bridge,to orthotopic liver transplantation.The success of such a therapeutic approach remains limited by the quality of the transplanted cells.Cryopreservation remains the best option for long-term storage of hepatocytes,providing a permanent and sufficient cell supply.However, isolated adult hepatocytes are poorly resistant to such a process,with a significant alteration both...