•The occurrence of resilience strongly coincides with short-term dynamics.•Adaptability is found mainly in long-term data sets.•In all case studies several disturbances with different operational ...scales were interlinked.
In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.
Late solid tumors (STs) are a significant cause of morbidity and mortality in long-term survivors of Hodgkin's disease. To investigate the carcinogenic potential of two different therapeutic ...approaches, we measured the relative risk (RR) of STs in patients with early-stage disease cured after primary full-dose (approximately 40 Gy) radiation therapy (RT) and in patients with advanced disease who were treated with chemotherapy followed by low-dose (15 to 30 Gy) involved-field radiation (CMT).
Because therapy-induced STs generally begin after a latency period of 5 to 10 years, we restricted our analysis to patients treated before 1986 who achieved durable remissions. Patients who required salvage chemotherapy or who died of Hodgkin's disease were excluded from analysis. The RR of STs was calculated by dividing the observed number of cases by the expected number in a matched population from the Connecticut Tumor Registry. The actuarial incidence of STs was also measured.
A total of 197 patients formed the RT group and 116 the CMT group. The median follow-up period in the RT group was 12.8 years, versus 13.5 years in the CMT group. The overall RR of STs in the CMT group was 1.5 (95% confidence interval CI, 0.6 to 3.5; P = .122). There were no cases of lung or breast cancer. In the RT group, the overall RR of STs was 3.3 (95% CI, 2.0 to 5.3; P < .001). There were seven cases of lung cancer (RR = 10.8; 95% CI, 5.3 to 22.2; P < .001) and two cases of breast cancer (RR = 2; 95% CI, 0.6 to 7.4; P = .07). All six benign tumors occurred in the RT group.
In patients cured by initial treatment for Hodgkin's disease, RT was associated with a statistically significant increase in STs, particularly lung cancer. CMT was not associated with a significant increase in STs. These data may have important implications for the design of newer therapies for early-stage Hodgkin's disease.
The response of cancer to chemotherapy can be quantified using (18)F-FDG to indicate changes in tumor metabolism. Quantification using the standardized uptake value (SUV) is more feasible for ...clinical practice than is the metabolic rate of (18)F-FDG (MRFDG), which requires longer, dynamic scanning. The relationship between MRFDG and SUV depends in part on how each accounts for blood clearance of tracer. We tested whether chemotherapy and treatment with granulocyte colony-stimulating factor (CSF) changed the blood clearance curves and therefore affected the relationship between MRFDG and SUV.
Thirty-nine patients with locally advanced breast cancer underwent (18)F-FDG PET before and after chemotherapy, including granulocyte CSF. The area under the curve (AUC) for blood clearance was determined before and after therapy. MRFDGs were determined by graphical analyses, whereas SUVs were calculated using the standard formula normalized by body weight. MRFDG and SUVs were compared with each other and with tumor response. Paired percentage changes in MRFDG and SUV were also divided into tertiles based on pretherapy SUV to investigate differences in the relative sensitivity of SUV changes to MRFDG changes due to baseline tumor uptake.
Despite a small but statistically significant 6% decrease in blood AUCs after therapy (P = 0.02), SUV and MRFDG did not differ significantly in slope (P = 0.53) or in correlation before and after therapy (r = 0.95 for both). Percentage changes in MRFDG and SUV between serial scans correlated with each other (r = 0.84) and with patient response (P <or= 0.06). The maximum detectable percentage change in SUV and the slope of percentage changes in MRFDG versus SUV for the patient tertile with the lowest baseline SUVs (65% +/- 5% +/-SE, slope (m) = 0.40 +/- 0.12, n = 13) were significantly lower than for the other patients (86% +/- 3%, m = 0.85 +/- 0.10, n = 26, P = 0.01 for both).
Chemotherapy and granulocyte CSF treatment resulted in a lower (18)F-FDG blood AUC. The maximum detectable percentage change in (18)F-FDG uptake is less when quantifying via static SUV than via dynamic MRFDG. This effect is small in most patients but may have clinical significance for measuring the response of patients with a low pretherapy (18)F-FDG uptake.
CP violation in B-meson decays Schubert, K. R.
The European physical journal. A, Hadrons and nuclei,
11/2003, Letnik:
18, Številka:
2-3
Journal Article
We previously demonstrated, in transgenic tobacco plants, that the role of the movement protein (MP) of tobacco mosaic virus is to facilitate the cell-to-cell spread of viral progeny during ...infection. An analysis of different tissues of these transgenic plants indicated that the MP accumulated in leaf, stem, and root tissue. The highest levels were detected in older leaves. The relative levels of MP in leaf tissue from transgenic plants were equivalent to, or higher than, the levels of MP in tobacco mosaic virus-infected leaf tissue. Results of subcellular fractionation of homogenates of transgenic leaf tissue showed that the MP was most abundant in the cell wall fraction of older leaves and that the protein remained at high levels in the cell wall fraction as the leaves continued to age. Significant levels of the MP were detected in a crude membrane/organelle fraction and a soluble fraction in younger leaves but decreased to low levels in older leaves. These results suggest that the MP accumulates and is stable in cell walls. We have previously shown that the MP modifies the molecular exclusion limit of plasmodesmata, which is consistent with the hypothesis that plant viruses move from cell to cell through altered plasmodesmata. We show here that the ability of the tobacco mosaic virus MP to modify the molecular exclusion limit of plasmodesmata in tobacco depends on the developmental stage of the leaf. The implications of these findings on understanding virus movement and how plasmodesmata function are discussed.
The growth and diversity of electronic journals (e-journals) in the past five years has led many to predict the extinction of print journals and that a new paradigm is sweeping scholarship. Some ...others, however, believe that future electronic scholarly journals will be different from their print antecedents and fill a different niche, and will be necessary for the growth of knowledge. This paper considers the future of e-journals in the light of the use and perception of graduate student end-users, and their expectations of future e-journals. Some results from a recent user study presenting significant implications for the design of future e-journals are reported. The results show a significantly high acceptance of e-journals by this category of users. Generally, e-journals are expected to be different from print journals, with novel forms of functionality not possible in their print counterparts.
N2-fixing root nodules of soybean (Glycine max L. Merr.) convert atmospheric N2 to ammonia(um) in an energy-intensive enzymatic reaction. These nodules synthesize large quantities of purines because ...nitrogen fixed by bacteria contained within this tissue is transferred to the shoots in the form of ureides, which are degradation products of purines. In animal systems, it has been proposed that proline biosynthesis by pyrroline-5-carboxylate reductase (P5CR) is used to generate the NADP+ required for the synthesis of the purine precursor ribose 5-phosphate. We have examined the levels, properties, and location of P5CR and proline dehydrogenase (ProDH) in soybean nodules. Nodule P5CR was found in the plant cytosol. Its activity was substantially higher than that reported for other animal and plant tissues and is 4-fold higher than in pea (Pisum sativum) nodules (which export amides). The Km for NADPH was lower by a factor of 25 than the Km for NADH, while the Vmax with NADPH was one-third of that with NADH. P5CR activity was diminished by NADP+ but not by proline. These characteristics are consistent with a role for P5CR in supporting nodule purine biosynthesis rather than in producing proline for incorporation into protein. ProDH activity was divided between the bacteroids and plant cytosol, but <2% was in the mitochondria-rich fractions. The specific activity of ProDH in soybean nodule bacteroids was comparable to that in rat liver mitochondria. In addition, we propose that some of the proline synthesized in the plant cytosol by P5CR is catabolized within the bacteroids by ProDH and that this represents a novel mechanism for transferring energy from the plant to its endosymbiont.
Formyltransferase catalyzes the reversible formation of formylmethanofuran from N5‐formyltetrahydromethanopterin and methanofuran, a reaction involved in the C1 metabolism of methanogenic and ...sulfate‐reducing archaea. The crystal structure of the homotetrameric enzyme from Methanopyrus kandleri (growth temperature optimum 98°C) has recently been solved at 1.65 Å resolution. We report here the crystal structures of the formyltransferase from Methanosarcina barkeri (growth temperature optimum 37°C) and from Archaeoglobus fulgidus (growth temperature optimum 83°C) at 1.9 Å and 2.0 Å resolution, respectively. Comparison of the structures of the three enzymes revealed very similar folds. The most striking difference found was the negative surface charge, which was −32 for the M. kandleri enzyme, only −8 for the M. barkeri enzyme, and −11 for the A. fulgidus enzyme. The hydrophobic surface fraction was 50% for the M. kandleri enzyme, 56% for the M. barkeri enzyme, and 57% for the A. fulgidus enzyme. These differences most likely reflect the adaptation of the enzyme to different cytoplasmic concentrations of potassium cyclic 2,3‐diphosphoglycerate, which are very high in M. kandleri (>1 M) and relatively low in M. barkeri and A. fulgidus. Formyltransferase is in a monomer/dimer/tetramer equilibrium that is dependent on the salt concentration. Only the dimers and tetramers are active, and only the tetramers are thermostable. The enzyme from M. kandleri is a tetramer, which is active and thermostable only at high concentrations of potassium phosphate (>1 M) or potassium cyclic 2,3‐diphosphoglycerate. Conversely, the enzyme from M. barkeri and A. fulgidus already showed these properties, activity and stability, at much lower concentrations of these strong salting‐out salts.
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