Adsorption of n-Pentane on Mesoporous Silica and Adsorbent Deformation

Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid−fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid−fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment, but for SBA-15 they are only qualitative. This deviation suggests that the elastic modulus of SBA-15 may change during pore filling

Preventive Antibacterial Therapy in Acute Ischemic Stroke: A Randomized Controlled Trial

BACKGROUND: Pneumonia is a major risk factor of death after acute stroke. In a mouse model, preventive antibacterial therapy with moxifloxacin not only prevents the development of post-stroke infections, it also reduces mortality, and improves neurological outcome significantly. In this study we investigate whether this approach is effective in stroke patients. METHODS: Preventive ANtibacterial THERapy in acute Ischemic Stroke (PANTHERIS) is a randomized, double-blind, placebo-controlled trial in 80 patients with severe, non-lacunar, ischemic stroke (NIHSS>11) in the middle cerebral artery (MCA) territory. Patients received either intravenous moxifloxacin (400 mg daily) or placebo for 5 days starting within 36 hours after stroke onset. Primary endpoint was infection within 11 days. Secondary endpoints included neurological outcome, survival, development of stroke-induced immunodepression, and induction of bacterial resistance. FINDINGS: On intention-to treat analysis (79 patients), the infection rate at day 11 in the moxifloxacin treated group was 15.4% compared to 32.5% in the placebo treated group (p = 0.114). On per protocol analysis (n = 66), moxifloxacin significantly reduced infection rate from 41.9% to 17.1% (p = 0.032). Stroke associated infections were associated with a lower survival rate. In this study, neurological outcome and survival were not significantly influenced by treatment with moxifloxacin. Frequency of fluoroquinolone resistance in both treatment groups did not differ. On logistic regression analysis, treatment arm as well as the interaction between treatment arm and monocytic HLA-DR expression (a marker for immunodepression) at day 1 after stroke onset was independently and highly predictive for post-stroke infections. INTERPRETATION: PANTHERIS suggests that preventive administration of moxifloxacin is superior in reducing infections after severe non-lacunar ischemic stroke compared to placebo. In addition, the results emphasize the pivotal role of immunodepression in developing post-stroke infections. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN74386719

Adsorption-Induced Deformation in Nanopores: Unexpected Results Obtained by Molecular Simulations

International audienceThe adsorption of a fluid in a nanoporous material induces deformations of the solid. The saturating regime, where the solid is filled with liquid, generally exhibits a linear relationship between the liquid pressure and the solid strain. This provides an experimental way to measure the elastic moduli of the solid walls. For large pores, the strain is determined by the pressure of the liquid saturating the pores and the mechanical properties of the porous solid. What happens at the nanometric scale, where liquid/matrix interfacial effects dominate? We have performed molecular simulations of a simple Lennard-Jones fluid confined between deformable nanoplatelets. The simulations provide the deformation of the nanopore as a function of the liquid pressure, in a way similar to what is done experimentally. The results show unexpected interface effects, which could be relevant to experimental data analysis

Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen

A prominent 19kDa surface antigen of Legionella pneumophila , cloned in Escherichia coli , was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA + gene fusions, generated by Tn phoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA + transposon insertions were also associated with loss of the 19 kDa antigen in immunoassay s using a monoclonal antibody (mAb1E9) and the replacement of the 19kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75712/1/j.1365-2958.1991.tb00824.x.pd

Integration of LCC and LCA results to higher system levels : The German meat and EU tomato cases

This report aims to highlight the potential contribution of food waste reduction to improving the sustainability of agri-food sector, by integrating the Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) results and upscaling them to a higher system level, using Germany meat and EU tomatoes as examples

Association of severe hypertension with pneumonia in elderly patients with acute ischemic stroke

Pneumonia is one of the most frequent complications in elderly patients with acute ischemic stroke. Although severe hypertension is often observed in the early phase of acute stroke, there are few studies of acute hypertension as a factor influencing the incidence of stroke-associated pneumonia (SAP) in elderly subjects with acute ischemic stroke. To assess the association of acute phase blood-pressure elevation with the incidence of SAP, we compared 10 elderly patients with acute ischemic stroke complicated with severe hypertension (⩾200/120 mm Hg) with 43 patients with moderate hypertension (160–199/100–119 mm Hg), as well as with 65 control normotensive or mildly hypertensive (<160/100 mm Hg) controls on admission. Data were collected on known risk factors, type of ischemic stroke and underlying chronic conditions. The significance of differences in risk factors was analyzed using univariate and multivariate comparisons of 38 SAP cases and others, 8 SAP death cases and others, and 28 patients with poor outcome associated with in-hospital death or artificial feeding at discharge and others. After adjustment for potential confounding factors, the relative risk estimates for SAP, SAP death and poor outcome were 2.83 (95% confidence interval 1.14–7.05), 5.20 (1.01–26.8) and 6.84 (1.32–35.4), respectively, for severe hypertension relative to normotensive or mildly hypertensive controls. We conclude that severe hypertension on admission is an independent predictive factor for SAP in elderly patients with acute ischemic stroke

The elementary events underlying force generation in neuronal lamellipodia

We have used optical tweezers to identify the elementary events underlying force generation in neuronal lamellipodia. When an optically trapped bead seals on the lamellipodium membrane, Brownian fluctuations decrease revealing the underlying elementary events. The distribution of bead velocities has long tails with frequent large positive and negative values associated to forward and backward jumps occurring in 0.1–0.2 ms with varying amplitudes up to 20 nm. Jump frequency and amplitude are reduced when actin turnover is slowed down by the addition of 25 nM Jasplakinolide. When myosin II is inhibited by the addition of 20 μM Blebbistatin, jump frequency is reduced but to a lesser extent than by Jasplainolide. These jumps constitute the elementary events underlying force generation

Pneumonia and in-hospital mortality in the context of neurogenic oropharyngeal dysphagia (NOD) in stroke and a new NOD step-wise concept

The aim of our work was to develop a step-wise concept for investigating neurogenic oropharyngeal dysphagia (NOD) that could be used by both trained nursing staff as well as swallowing therapists and physicians to identify patients with NOD at an early stage and so enable an appropriate therapy to be started. To achieve this objective, we assessed uniform terminology and standard operating procedures (SOP) in a new NOD step-wise concept. In-house stroke mortality rates and rates of pneumonia were measured over time (2003–2009) in order to show improvements in quality of care. In addition, outcome measures in a stroke-unit monitoring system were studied after neurorehabilitation (day 90) assessing quality of life (QL) and patient feedback. An investigation that was carried out in the context of internal and external quality assurance stroke projects revealed a significant correlation between the NOD step-wise concept and low rates of pneumonia and in-house mortality. The quality of life measures show a delta value that can contribute to “post-stroke” depression. The NOD step-wise concept (NSC) should, on the one hand, be capable of being routinely used in clinical care and, on the other, being able to fulfil the requirements of being scientifically based for investigating different stages of swallowing disorders. The value of our NSC relates to the effective management of clinical resources and the provision of adequate diagnostic and therapeutic options for different grades of dysphagia. We anticipate that our concept will provide substantial support to physicians, as well as swallowing therapists, in clinical settings and rehabilitation facilities, thereby promoting better guidance and understanding of neurogenic dysphagia as a concept in acute and rehabilitation care, especially stroke-unit settings

Force-Velocity Measurements of a Few Growing Actin Filaments

The authors propose a new mechanism for actin-based force generation based on results using chains of actin-grafted magnetic colloids

A New Microsphere-Based Immunoassay for Measuring the Activity of Transcription Factors

There are several traditional and well-developed methods for analyzing the activity of transcription factors, such as EMSA, enzyme-linked immunosorbent assay, and reporter gene activity assays. All of these methods have their own distinct disadvantages, but none can analyze the changes in transcription factors in the few cells that are cultured in the wells of 96-well titer plates. Thus, a new microsphere-based immunoassay to measure the activity of transcription factors (MIA-TF) was developed. In MIA-TF, NeutrAvidin-labeled microspheres were used as the solid phase to capture biotin-labeled double-strand DNA fragments which contain certain transcription factor binding elements. The activity of transcription factors was detected by immunoassay using a transcription factor-specific antibody to monitor the binding with the DNA probe. Next, analysis was performed by flow cytometry. The targets hypoxia-inducible factor-1α (HIF-1α) and nuclear factor-kappa B (NF-κB) were applied and detected in this MIA-TF method; the results that we obtained demonstrated that this method could be used to monitor the changes of NF-κB or HIF within 50 or 100 ng of nuclear extract. Furthermore, MIA-TF could detect the changes in NF-κB or HIF in cells that were cultured in wells of a 96-well plate without purification of the nuclear protein, an important consideration for applying this method to high-throughput assays in the future. The development of MIA-TF would support further progress in clinical analysis and drug screening systems. Overall, MIA-TF is a method with high potential to detect the activity of transcription factors