Artefactual cleavage of E coli H-NS by OmpT

In the bacterium Escherichia coli, H-NS-(H1, H1a) is a heat-stable protein with a molecular mass of 15.5 kDa involved in nucleoid organisation and gene regulation linked to certain signal transduction pathways. We have shown that, following addition of preparations of everted inner membrane vesicles, heat-stable cleavage products of approximately 10 kDa of H-NS are formed in vitro from newly synthesised, radio-labelled H-NS and from purified H-NS. The 15.5 kDa protein and its cleavage products were also recovered from a minicell system. These results raised the possibility that cleavage of H-NS is physiologically significant. However, the cleavage of H-NS observed appears to occur during cell breakage and to depend on the method of protein extraction and the presence of the outer membrane protease, OmpT. Nevertheless, the results indicate that H-NS may contain at least two separate domains with cleavage occurring between these domains at a preferred OmpT site. Failure to take account of H-NS cleavage in sample preparation and analysis can lead to serious underestimation of H-NS levels.     

Thoracic and abdominal SPECT-CT image fusion without external markers in endocrine carcinomas. The Group of Thyroid Tumoral Pathology of Champagne-Ardenne

Superimposition of SPECT and computed tomography (CT) slices from the thoracoabdominal region was achieved without the use of external markers for 14 studies in 13 patients with endocrine carcinoma. Technical feasibility and clinical validation of this retrospective fusion method were assessed. METHODS: Patients had a history of thyroid cancer or of carcinoid tumor. To detect tumor sites, CT scan and dual-isotope tomoscintigraphy were performed, with 99mTc-hydroxymethylene diphosphonate for bone scintigraphy and with 111In-pentetreotide, 131I or 131I-metaiodobenzylguanidine for tumor scintigraphy (TS). A superimposition method previously developed for the pelvic region was adapted to the nonrigid thoraco-abdominal region. CT-bone scintigraphy and CT-TS superimposed images were obtained. Clinical validation of the information obtained from the superimposed images was obtained from surgery or follow-up imaging studies performed after clinical evolution of the disease process. RESULTS: Reliable and reproducible registration was achieved in all patients. CT-TS superimposed images produced accurate localization of abnormal TS foci. Accuracy was limited primarily by variable relative displacements of the thoracoabdominal organs. For 10 sites in 8 patients, localization and/or characterization obtained from CT-TS images was confirmed by a reference technique. Superimposition enabled the localization of tumor sites that otherwise could not have been suspected from CT alone and allowed the characterization of CT suspicious masses and the confirmation of CT positive sites. Nonspecific tumor TS uptake sites were also localized. CONCLUSION: With standard CT and dual-isotope SPECT acquisitions, SPECT-CT fusion is feasible in the thoracoabdominal region without the use of external markers. Fused images were validated in 8 patients for 10 sites. The use of this technique could probably improve the management and care of patients with endocrine carcinoma.     

Study of the nutrient distribution in root tips of the tropical forage Brachiaria

A Brachiaria breeding project is being conducted at CIAT, Colombia to combine acid soil adaptation of B. decumbens with other favourable traits of Brachiaria species that are less adapted to acid soils. Micro-PIXE was applied to investigate nutrient uptake and distribution in root tips of different species grown in hydroponic culture under control and simulated acid soil stress conditions. Different sample measurement approaches were evaluated, including: (1) linear scans with single point measurements along the root axis; (2) mapping of whole root tips; and (3) mapping of root cross sections. Different tissue types could be distinguished on the base of differences in nutrient concentrations and/or Al stress. Al, if supplied under nutrient stress conditions, increased P accumulation in the central vascular tissue of the meristematic and elongation zone of B. decumbens and B. brizantha. Furthermore, a negative correlation was found between Al and Cl accumulation in the root cap of B. decumbens.     

Engraftment of allogeneic hematopoietic progenitor cells with purine analog-containing chemotherapy: harnessing graft-versus-leukemia without myeloablative therapy

The immune-mediated graft-versus-leukemia effect is important to prevent relapse after allogeneic progenitor cell transplantation. This process requires engraftment of donor immuno-competent cells. The objective of this study was to assess the feasibility of achieving engraftment of allogeneic peripheral blood or bone marrow progenitor cell after purine analog containing nonmyeloablative chemotherapy. Patients with advanced leukemia or myelodysplastic syndromes (MDS) who were not candidates for a conventional myeloablative therapy because of older age or organ dysfunction were eligible. All patients had an HLA-identical or one-antigen-mismatched related donor. Fifteen patients were treated (13 with acute myeloid leukemia and 2 with MDS). The median age was 59 years (range, 27 to 71 years). Twelve patients were either refractory to therapy or beyond first relapse. Eight patients received fludarabine at 30 mg/m2/d for 4 days with idarubicin at 12 mg/m2/d for 3 days and ara-c at 2 g/m2/d for 4 days (n = 7) or melphalan at 140 mg/m2/d (n = 1). Seven patients received 2-chloro-deoxyadenosine at 12 mg/m2/d for 5 days and ara-C 1 at g/m2/d for 5 days. Thirteen patients received allogeneic peripheral blood stem cells and 1 received bone marrow after chemotherapy. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and methyl-prednisolone. Treatment was generally well tolerated, with only 1 death from multiorgan failure before receiving stem cells. Thirteen patients achieved a neutrophil count of greater than 0.5 x 10(9)/L a median of 10 days postinfusion (range, 8 to 17 days). Ten patients achieved platelet counts of 20 x 10(9)/L a median of 13 days after progenitor cell infusion (range, 7 to 78 days). Eight patients achieved complete remissions (bone marrow blasts were < 5% with neutrophil recovery and platelet transfusion independence) that lasted a median of 60 days posttransplantation (range, 34 to 170+ days). Acute GVHD grade > or = 2 occurred in 3 patients. Chimerism analysis of bone marrow cells in 6 of 8 patients achieving remission showed > or = 90% donor cells between 14 and 30 days postinfusion, and 3 of 4 patients remaining in remission between 60 and 90 days continued to have > or = 80% donor cells. We conclude that purine analog-containing nonmyeloablative regimens allow engraftment of HLA-compatible hematopoietic progenitor cells. This approach permits us to explore the graft-versus-leukemia effect without the toxicity of myeloablative therapy and warrants further study in patients with leukemia who are ineligible for conventional transplantation with myeloablative regimens either because of age or concurrent medical conditions.     

Effects of ACh on the electric activity of rostral ventrolateral medullary neurons of rat in vitro

Extracellular single-unit discharges were obtained from 165 spontaneously active neurons within the region of the rostral ventrolateral medulla (RVLM) by glass microelectrode from 89 brain slices of the Sprague-Dawley rats. The units could be divided into three types: regular (61.8%), irregular (24.2%) and silent (14%). Acetylcholine (ACh, 0.1, 0.3 mumol/L) showed four kinds of effects on spontaneous discharges of RVLM neurons: excitatory, inhibitory, biphasic and non-responsive, counting respectively 41.8%, 20%, 3% and 35.2% of the neurons tested. The excitatory effect of ACh was dose-dependent. The effects, either excitatory or inhibitory, of ACh (n = 49) were mostly blocked by atropine (0.3 mumol/L, n = 42). The excitatory effect of ACh (n = 14) could be blocked mainly by selective antagonist of M1 receptor, pirenzepine (PZ, 30 nmol/L, n = 9), but not by selective antagonist of M2 receptor, methoctramine (MT) and AFDX-116. The inhibitory effect of ACh (n = 10) could be blocked mostly by M2 receptor antagonist MT (30 nmol/L, n = 7); and this inhibitory effect (n = 9) could be blocked mostly by another M2 receptor antagonist AFDX-116 (30 nmol/L, n = 6), but not by M1 receptor antagonist PZ.     

Polynomial-complexity deadlock avoidance policies for sequentialresource allocation systems

The development of efficient deadlock avoidance policies (DAPs) for sequential resource allocation systems (RASs) is a problem of increasing interest in the scientific community, largely because of its relevance to the design of large-scale flexibly automated manufacturing systems. Much of the work on this problem existing in the literature is focused on the so-called single-unit RAS model, which is the simplest model in the considered class of RASs. Furthermore, due to a well-established result stating that, even for single-unit RASs, the computation of the maximally permissive DAP is intractable (NP-hard), many researchers (including our group) have focused on obtaining good suboptimal policies which are computationally tractable (scalable) and provably correct. In the first part of the paper, it is shown, however, that for a large subset (in fact, a majority) of single-unit RASs, the optimal DAP can be obtained in real-time with a computational cost which is a polynomial function of the system size (i.e., the number of resource types and the distinct route stages of the processes running through the system). The implications of this result for the entire class of single-unit RASs are also explored. With a result on the design of optimal DAPs for single-unit RASs, the second part of the paper concentrates on the development of scalable and provably correct DAPs for the more general case of conjunctive RASs     

Infinite-dimensional convex optimization in optimal and robustcontrol theory

Many engineering problems can be shown to be equivalent to solving semidefinite programs (SPs), i.e., convex optimization problems involving linear matrix inequalities (LMIs). Powerful computation tools are available for such problems in the finite-dimensional case. However, the problems arising in optimal and robust control theory are often infinite dimensional, and so adequate computation tools are not available. The key to tackling such problems with finite computation tools is to have a primal-dual formulation of the problem without duality gap. In this paper we study infinite-dimensional SPs and present a lifting technique to recast SPs as parameterized linear programs (LPs). This enables the wealth of theoretical tools available for infinite-dimensional LPs to be extended to infinite-dimensional SPs. In particular, we develop some new sufficient conditions for the lack of a duality gap for infinite-dimensional SPs and give an exact characterization of the primal and dual problems for these cases. Both primal and dual problems are formed as infinite-dimensional SP problems, with finite truncations to each giving upper and lower bounds, respectively, on the exact solution to the infinite-dimensional problem. Thus, these results can form the basis of practical computation schemes for infinite-dimensional problems, which require only finite-dimensional computation tools. To illustrate the power of these tools we apply the results to two previously unsolved optimization problems, namely minimizing the l₁ norm of a closed-loop system subject to bounds on the frequency response magnitude at a finite number of points and/or bounds on the H₂ norm     

New advances on a posteriori error on constitutive relation in f.e. analysis

This paper deals with error estimators based on residuals on the constitutive relation which have been developed for the past 20 years at Cachan. Especially in the case of elasticity, these error estimators can become poor in situations where the material and the mesh are strongly anisotropic. The crucial point herein is the construction of equilibrated stress fields from the computed finite element solution. Therefore, in this paper, the approach and in particular this last point are re-examined. Several important modifications are introduced in the concepts and basic techniques. Hence, a new generation of error estimators which seem to be extremely robust upon initial applications has been generated.     

Effect of dynamic strain ageing on the tensile properties of a modified 9Cr–1Mo steel

Tensile testing of a modified 9Cr–1Mo steel in two microstructural conditions (710T– normalized at 1100°C, tempered at 710°C, and 550T – normalized at 1100°C tempered at 550°C) in the temperature range 25–450°C, under strain rates of 2.3×10-5–2.3×10-3s-1, exhibited serrated flow curves, with serrations appearing almost at the onset of deformation and disappearing before ultimate strengths were attained. The serrated flow curves (characteristics of dynamic strain ageing) were accompanied by increased ultimate strengths, loss of ductility and negative strain-rate sensitivity, relative to the ambient temperature properties. However, the increase in ultimate strength and the reduction in ductility were much larger for 710T specimens, as compared to 550T ones. In the dynamic strain ageing regime, the work-hardenability of 710T specimens increased rapidly while that of 550T specimens remained practically unaffected. Based on the microstructural consideration and the observed activation energy of 45 kJ mol-1, it is proposed that serrations are initiated by a nitrogen atmosphere formation on the waiting dislocations by a pipe diffusion mechanism, and they disappear by diffusion to the precipitate sinks during deformation. Because the fine alloy carbide precipitates in 550T specimens are more effective sinks than those of 710T ones, they can cause much faster depletion of the atmosphere, resulting in a much smaller effect of dynamic strain ageing on the tensile properties of 550T specimens.