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91.
92.
Elevated plasma lipid concentrations and increased platelet activation are risk factors in the development of atherosclerosis. Nine patients with type IIa hyperlipoproteinemia and nine patients with type IV hyperlipoproteinemia were given soya lecithin, 12 g/day, for 3 months. Plasma cholesterol and triglycerides were reduced by 15 and 23%, respectively, and HDL-cholesterol increased by 16% in the hypercholesterolemic patients. Platelet function was unchanged. In the hypertriglyceridemic patients, total cholesterol fell by 18%, triglycerides by 36%, and HDL-cholesterol increased by 14%. There was a 27% reduction in platelet aggregation (P less than 0.01). Seventeen hypertriglyceridemic patients then received increasing doses of soya lecithin for 1-month periods (6, 12, and 18 g/day). The optimal lipoprotein-lowering effect was achieved with a daily dose of 12 g soya lecithin per day. Both low-density lipoprotein and very-low-density lipoprotein levels were reduced, and HDL-cholesterol and apolipoprotein levels were reduced, and HDL-cholesterol and apolipoprotein A-I concentrations were increased. Platelet aggregation in response to collagen and ADP was significantly reduced, parallel with the reduction in triglyceride level. Soya lecithin supplementing the diet may be useful in the management of the hypertriglyceridemic patient. 相似文献
93.
Local and global pyrogeographic evidence that indigenous fire management creates pyrodiversity 下载免费PDF全文
Clay Trauernicht Barry W. Brook Brett P. Murphy Grant J. Williamson David M. J. S. Bowman 《Ecology and evolution》2015,5(9):1908-1918
Despite the challenges wildland fire poses to contemporary resource management, many fire‐prone ecosystems have adapted over centuries to millennia to intentional landscape burning by people to maintain resources. We combine fieldwork, modeling, and a literature survey to examine the extent and mechanism by which anthropogenic burning alters the spatial grain of habitat mosaics in fire‐prone ecosystems. We survey the distribution of Callitris intratropica, a conifer requiring long fire‐free intervals for establishment, as an indicator of long‐unburned habitat availability under Aboriginal burning in the savannas of Arnhem Land. We then use cellular automata to simulate the effects of burning identical proportions of the landscape under different fire sizes on the emergent patterns of habitat heterogeneity. Finally, we examine the global extent of intentional burning and diversity of objectives using the scientific literature. The current distribution of Callitris across multiple field sites suggested long‐unburnt patches are common and occur at fine scales (<0.5 ha), while modeling revealed smaller, patchy disturbances maximize patch age diversity, creating a favorable habitat matrix for Callitris. The literature search provided evidence for intentional landscape burning across multiple ecosystems on six continents, with the number of identified objectives ranging from two to thirteen per study. The fieldwork and modeling results imply that the occurrence of long‐unburnt habitat in fire‐prone ecosystems may be an emergent property of patch scaling under fire regimes dominated by smaller fires. These findings provide a model for understanding how anthropogenic burning alters spatial and temporal aspects of habitat heterogeneity, which, as the literature survey strongly suggests, warrant consideration across a diversity of geographies and cultures. Our results clarify how traditional fire management shapes fire‐prone ecosystems, which despite diverse objectives, has allowed human societies to cope with fire as a recurrent disturbance. 相似文献
94.
95.
Effector and memory CD8+ T cells can be generated in response to alloantigen independently of CD4+ T cell help 总被引:3,自引:0,他引:3
Jones ND Carvalho-Gaspar M Luo S Brook MO Martin L Wood KJ 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(4):2316-2323
There is now considerable evidence suggesting that CD8(+) T cells are able to generate effector but not functional memory T cells following pathogenic infections in the absence of CD4(+) T cells. We show that following transplantation of allogeneic skin, in the absence of CD4(+) T cells, CD8(+) T cells become activated, proliferate, and expand exclusively in the draining lymph nodes and are able to infiltrate and reject skin allografts. CD44(+)CD8(+) T cells isolated 100 days after transplantation rapidly produce IFN-gamma following restimulation with alloantigen in vitro. In vivo CD44(+)CD8(+) T cells rejected donor-type skin allografts more rapidly than naive CD8(+) T cells demonstrating the ability of these putative memory T cells to mount an effective recall response in vivo. These data form the first direct demonstration that CD8(+) T cells are able to generate memory as well as effector cells in response to alloantigen during rejection in the complete absence of CD4(+) T cells. These data have important implications for the design of therapies to combat rejection and serve to reinforce the view that CD8(+) T cell responses to allografts require manipulation in addition to CD4(+) T cell responses to completely prevent the rejection of foreign organ transplants. 相似文献
96.
Imminent shifts in environmental parameters due to climatic change might have profound ramifications for wetlands listed under the Ramsar convention. Although the exact mechanisms by which global change will affect these systems are not known, models that simulate component drivers, particularly at a broad spatial scale, can nevertheless allow for more informed conservation decision making. Such general inference is particularly needed for wetlands across the tropics, where less knowledge and fewer resources are available to mitigate the impacts on important conservation sites. Here we develop a case study of wetland loss to sea level rise across tropical north Australia (including Ramsar‐listed sites), and link these to a metapopulation model for a keystone endemic waterbird, the magpie goose Anseranas semipalmata. We projected published models on sea level rise through to the year 2400, and found a non‐linear trajectory of inundation up to 20 m above present levels. Digital elevation models were used to simulate sea level rise and the spatially differentiated loss of wetland habitat used by geese. Range retraction was linked to decline in ecological carrying capacity, and we coupled wetland‐specific habitat loss projections to a spatially explicit demographic metapopulation model. Additionally, we included alternate harvest strategies based on present‐day estimates of indigenous and non‐indigenous offtake of geese, and examined the synergy between wetland loss and hunting on extinction risk. Our results suggest that Australia's once‐abundant and widespread magpie goose will be reduced to a fragmented population of just a few thousand individuals within the next 200–300 yr. Harvest could continue for some time, up to a “tipping point” at around 5% loss of current wetland habitat, after which the decline of geese is rapid. Given the inexorable nature of sea level rise, short‐ to medium‐term conservation of waterbirds across Ramsar wetlands must prepare for adaptive wetland management, such as through buffer‐placement, and ongoing monitoring of harvest. 相似文献
97.
I. Brook 《Journal of applied microbiology》1990,69(5):697-700
B rook , I. 1990. Growth of Bacteroides fragilis group in agar and broth media. Journal of Applied Bacteriology 69 , 697–700.
The rate of bacterial growth of four . Bacteroides fragilis group organisms was determined in agar and broth media. Exponential bacterial growth occurred in agar media within 4 to 8 h, while such growth was delayed in broth media and occurred within 12–24 h after inoculation. This phenomenon may explain why antimicrobials which manifest an 'inoculum effect' may show increased resistance to antimicrobials when tested in agar media. 相似文献
The rate of bacterial growth of four . Bacteroides fragilis group organisms was determined in agar and broth media. Exponential bacterial growth occurred in agar media within 4 to 8 h, while such growth was delayed in broth media and occurred within 12–24 h after inoculation. This phenomenon may explain why antimicrobials which manifest an 'inoculum effect' may show increased resistance to antimicrobials when tested in agar media. 相似文献
98.
Global average temperature increase during the last century has induced species geographic range shifts and extinctions. Montane floras, in particular, are highly sensitive to climate change and mountains serve as suitable observation sites for tracing climate-induced biological response. The Himalaya constitute an important global biodiversity hotspot, yet studies on species’ response to climate change from this region are lacking. Here we use historical (1849–50) and the recent (2007–2010) data on temperature and endemic species’ elevational ranges to perform a correlative study in the two alpine valleys of Sikkim. We show that the ongoing warming in the alpine Sikkim Himalaya has transformed the plant assemblages. This study lends support to the hypothesis that changing climate is causing species distribution changes. We provide first evidence of warmer winters in the region compared to the last two centuries, with mean temperatures of the warmest and the coldest months may have increased by 0.76±0.25°C and 3.65±2°C, respectively. Warming-driven geographical range shifts were recorded in 87% of 124 endemic plant species studied in the region; upper range extensions of species have resulted in increased species richness in the upper alpine zone, compared to the 19th century. We recorded a shift of 23–998 m in species’ upper elevation limit and a mean upward displacement rate of 27.53±22.04 m/decade in the present study. We infer that the present-day plant assemblages and community structure in the Himalaya is substantially different from the last century and is, therefore, in a state of flux under the impact of warming. The continued trend of warming is likely to result in ongoing elevational range contractions and eventually, species extinctions, particularly at mountaintops. 相似文献
99.
Exposure to whole-body irradiation is associated with fatal gram-negative sepsis. The optimal length of therapy of such infection is not established. The effect of short and long courses of oral therapy with the quinolone ofloxacin for orally acquired Klebsiella pneumoniae infection was tested in B6D2F1 mice exposed to 8.0 Gy of bilateral radiation from 60Co. A dose of 10(8) organisms was given orally 4 days after irradiation, and therapy was started 1 day later. Cultures of the ileum 7 days after irradiation showed the recovery of K. pneumoniae in 7 of 10 untreated mice and in 3 of 20 treated with ofloxacin. However, 14 days after irradiation K. pneumoniae was isolated in 5 of 6 untreated mice, in 7 of 9 that received the short course of therapy, and in one of those that received the long course of therapy (P less than 0.05). At Day 7, K. pneumoniae was isolated from the livers of 6 of 10 untreated mice, and from none of those receiving ofloxacin (P less than 0.05). At 14 days, K. pneumoniae was isolated in 4 of 6 untreated animals, in 4 of 9 that received the short course of therapy, and in none of the mice that received the long course of therapy (P less than 0.05). Only 3 of 20 (15%) untreated mice survived for 30 days as compared to 11 of 20 (55%) mice treated for 7 days with ofloxacin and 18 of 20 (90%) mice treated for 21 days with ofloxacin (P less than 0.05). These survival data illustrate the efficacy of a 21-day course over a 7-day course of ofloxacin therapy for orally acquired K. pneumoniae infection in irradiated hosts. 相似文献
100.
Allan E. Strand Brook G. Milligan Casey M. Pruitt 《Evolution; international journal of organic evolution》1996,50(5):1822-1829
The degree to which conspecific populations are interconnected via ongoing gene flow remains an important focus of evolutionary biology. One major difficulty in distinguishing ongoing gene flow from historical subdivision is that either process can generate similar estimates of apparent gene flow. Thus, gene flow estimates themselves are insufficient to distinguish between these alternatives. However, genetic data coupled with additional information about demography and distribution do allow a distinction to be made. Here we address the specific question, does gene flow link populations of Aquilegia? In a survey of a 525 B.P. chloroplast DNA fragment sampled from 251 individual plants from 18 populations of three taxa, five haplotypes were identified. No significant relationship between geographic distance and apparent gene flow between population pairs existed. Further, the estimated level of gene flow was entirely compatible with a historical subdivision of Aquilegia populations during the late Pleistocene or early Holocene. Therefore, these patterns of variation are due not to ongoing gene flow, but rather to historical association among populations. Thus Aquilegia populations may be considered as distinct evolutionary entities with regard to seed-mediated processes. As a result, comparative analysis of ecological traits undergoing potentially rapid evolution (e.g., life histories, mating systems, inbreeding depression) should be possible in these taxa. 相似文献