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Variable Period (variable + period)
Selected AbstractsSpatio-temporal dynamics and local hotspots of initial recruitment in vertebrate-dispersed treesJOURNAL OF ECOLOGY, Issue 4 2008Arndt Hampe Summary 1Initial recruitment, or the arrival and establishment of propagules, is the most variable period in the life cycle of long-lived plants, and the extent to which studies of initial recruitment can be used to predict patterns of regeneration remains unresolved. 2We investigated the spatio-temporal dynamics of initial recruitment across five populations of three fleshy-fruited tree species from contrasting environments. Among-year variation in total seedfall, dispersed seedfall and seedling distributions was examined using analytical approaches that are new to the field and that explicitly incorporate space and allow comparisons among studies. 3Observed patterns ranged from remarkable across-year consistency in seedfall distributions and strong spatial coupling between seed and seedling stages to extensive variation and almost complete independence of stages. Spatial distributions of frugivore-mediated seedfall were markedly more consistent than those of the total seedfall in two of the five populations. Seedling distributions were generally more variable among years than seedfall distributions. 4All populations showed a positive relationship between the long-term mean density of recruitment at a given microsite and its year-to-year consistency. This relationship remained valid when considering only microsites away from fruiting tree canopies (i.e. those receiving actually dispersed seeds), and was virtually independent of their distance to the nearest fruiting tree. 5Synthesis. Our results point to the existence of some general rules behind the idiosyncratic recruitment dynamics of perennial plant populations, which should help with projecting spatial patterns of plant establishment in long-lived species. In particular, those microsites that combine a great intensity with a high year-to-year consistency of recruitment should represent potential regeneration ,hotspots' whose identification and characterization can be of great use for the management and conservation of naturally regenerating tree populations. [source] Broods of attractive three-spined stickleback males require greater paternal careJOURNAL OF FISH BIOLOGY, Issue 4 2006T. C. M. Bakker The relationship between egg number and survival in nests of three-spined sticklebacks Gasterosteus aculeatus was tested in the field. Nests were deprived of paternal care during a variable period by removal of the father while preventing egg predation by protection of the nest by a net. Upon male removal, a number of male traits were quantified. Nest-content variables and embryo survival were assessed at the end of the deprivation period. Proportional egg mortality was significantly positively correlated with the length of the deprivation period, the number of eggs present in the nest and egg size, thus suggesting that nests with more and larger eggs need more paternal care. Males with the most symmetrical ventral spines achieved the highest reproductive success as measured by the number of eggs in the nest. In addition, their nests contained relatively larger eggs. Spine length symmetry correlated with the blue intensity of the eye thus giving females several cues to assess male quality. [source] Risk of dispersal in western spruce budwormAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2009Vincent G. Nealis Abstract 1,Western spruce budworm Choristoneura occidentalis Free. larvae emerge in the spring before buds have expanded and spend a variable period of time foraging on branches and mining needles. 2,Losses of dispersing budworms during this needle-mining period are related directly to the severity of defoliation in previous years and inversely related to foliage biomass in the study plot and to temperature and rainfall during the needle-mining period. 3,Losses can be interpreted in terms of risk of dispersal, which is the product of the propensity of early-stage budworms to disperse in search of resources and the consequences of this behaviour for survival under variable ecological conditions. 4,A comparison of the species-specific nature of risk of dispersal in three conifer-feeding budworm systems of North America may elucidate the common nature but variable features of their respective population dynamics. [source] Observance of Antiplatelet Therapy after Stent Implantation in Patients under Chronic Oral Anticoagulant TreatmentJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 3 2008JOSÉ VALENCIA M.D., Ph.D. Purpose: Patients undergoing coronary stenting must take dual antiplatelet therapy during a variable period. The combination of chronic oral anticoagulants (COA) with antiplatelet therapy has been related to an increased risk of hemorrhage. The aim of this study was to evaluate the level of the antiplatelet therapy observance in those patients and the incidence of adverse events after 1 year. Methods: Patients with prior COA treatment with coronary lesions suitable for stenting were included. Clinical assessment was performed on admission, with follow-up at 1, 6, and 12 months. Antiplatelet and COA treatment, adverse cardiac events, and hemorrhagic episodes were registered. Results: A total of 70 patients were included. Mean age was 70.5 ± 8.7 years. The most common cause of COA was atrial fibrillation. Conventional stents were used in 40% and drug-eluting stents (DES) in 60%. Treatment at discharge was: ASA + clopidogrel + COA 64.2%, ASA + clopidogrel 25.4%, COA + clopidogrel 7.5%, and COA + ASA 3%. Observance of antiplatelet and COA therapy at 1-6-12 month follow-up after conventional stent was: COA 73.1-70.8-69.6%; ASA 92.3-75.4-65.2%; clopidogrel 92.3-62.5-43.5%. In patients receiving DES, it was: COA 76.9-78.9-80.6%, ASA 79.5-65.8-55.7%, and clopidogrel 94.9-84.2-61.1%. Dual antiplatelet therapy in patients with DES over these periods was taken in 79.5-51.4-27.8%, respectively. The incidence of adverse events was minor bleeding 11.4%, major bleeding 8.6%, myocardial infarction 4.3%, stent thrombosis 1.4%, and death 12.8%. Conclusions: There is a great variability in the treatment prescribed at discharge. Low observance with dual antiplatelet therapy has been detected in these patients, particularly after DES implantation, and they present a very high rate of complications in the follow-up. [source] Short-term food deprivation does not improve the efficacy of a fish oil finishing strategy in Murray codAQUACULTURE NUTRITION, Issue 6 2009G. PALMERI Abstract Two groups of fish (Maccullochella peelii peelii) were fed for a 90-day conditioning period on a canola oil diet (CO) or a fish oil diet (FO). Canola oil diet fed fish were then shifted to the FO diet for a 90-day finishing period. A variable period of starvation (0, 5, 10 and 15 days) was introduced to reduce the initial lipid level of CO fed fish at the beginning of the finishing period and therefore accelerate the rate of recovery of FO-like fatty acids. During starvation, fish did not show significant reduction in total lipid content, either in the fillet or whole body. At the end of the conditioning period, fatty acid composition of the diet was mirrored in fish tissues. These differences came close to levelling out following re-feeding, with the exception of n - 6 polyunsaturated fatty acids (PUFA). However, no effects of the starvation periods on the final fatty acid make-up of fish were recorded. The results of this trial show that Murray cod, when subjected to a starvation period of up to 15 days, does not lose an appreciable quantity of lipid and, therefore, the tested starvation approach to reduce the initial level of lipid has to be considered unsuccessful. [source] Effects of anti-CD154 treatment on B cells in murine systemic lupus erythematosusARTHRITIS & RHEUMATISM, Issue 2 2003Xiaobo Wang Objective To determine the immunologic effects of anti-CD154 (CD40L) therapy in the (NZB × NZW)F1 mouse model of systemic lupus erythematosus. Methods Twenty-week-old and 26-week-old (NZB × NZW)F1 mice were treated with continuous anti-CD154 therapy. Mice were followed up clinically, and their spleens were studied at intervals for B and T cell numbers and subsets and frequency of anti,double-stranded DNA (anti-dsDNA),producing B cells. T cell,dependent immunity was assessed by studying the humoral response to the hapten oxazolone. Results IgG anti-dsDNA antibodies decreased during therapy and disease onset was delayed, but immune tolerance did not occur. During treatment, there was marked depletion of CD19+ cells in the spleen; however, autoreactive IgM-producing B cells could still be detected by enzyme-linked immunospot assay. In contrast, few IgG- and IgG anti-dsDNA,secreting B cells were detected. Eight weeks after treatment cessation, the frequency of B cells producing IgG anti-dsDNA antibodies was still decreased in 50% of the mice, and activation and transition of T cells from the naive to the memory compartment were blocked. Anti-CD154 treatment blocked both class switching and somatic mutation and induced a variable period of relative unresponsiveness of IgG anti-dsDNA,producing B cells, as shown by decreased expression of the CD69 marker and failure to generate spontaneous IgG anti-dsDNA,producing hybridomas. Treated mice mounted an attenuated IgM response to the hapten oxazolone and produced no IgG antioxazolone antibodies. Conclusion Anti-CD154 is a B cell,depleting therapy that affects multiple B cell subsets. Activation of both B and T cells is prevented during therapy. After treatment cessation, autoreactive B cells progress through a series of activation steps before they become fully competent antibody-producing cells. The general immunosuppression induced during treatment will need to be taken into account when using B cell,depleting regimens in humans. [source] Improving the outcome of cord blood transplantation: use of mobilized HSC and other cells from third party donorsBRITISH JOURNAL OF HAEMATOLOGY, Issue 2 2009Manuel N. Fernández Summary We developed the strategy of umbilical cord blood transplants (UCBT) with co-infusion of a limited number of highly purified mobilized haematopoietic stem cells (MHSC) from a human leucocyte antigen (HLA) unrestricted third party donor (TPD). Short post-transplant periods of neutropenia were usually observed in adults with haematological neoplasms receiving UCBT with a relatively low cell content and 0,3 HLA mismatches after myeloablative conditioning. This resulted from an early and initially predominant engraftment of the TPD,MHSC. After a variable period of double complete TPD + UCB chimerism, final full UCB chimerism was achieved (cumulative incidence >90%) within 100 d. Early recovery of the circulating neutrophils resulting from the ,bridge transplant' of the TPD,MHSC reduced the incidence of serious neutropenia-related infections, also facilitating the use of drugs with myelosuppressive side effects to combat other infections. The observed incidence of graft- versus -host disease and relapses was low, with overall and disease-free survival curves comparable to those of HLA identical sibling transplants. Post-transplant recovery of natural killer cells occurred soon after the transplant and B cells recovered around 6 months, but T-cell recovery took more than 1 year. Available data show that T cell recovery derives from UCB,HSC through thymic differentiation and that cytomegalovirus (CMV)-specific lymphocytes develop following CMV reactivations. [source] | |||||||||||||