Plant cells : immobilization and oxygen transfer

The study described in this thesis is part of the integrated project 'Biotechnological production of non-persistent bioinsecticides by means of plant cells invitro ' and was done in close cooperation with the research Institute Ital within the framework of NOVAPLANT. The plant cells used in this project were Tagetes species which produce thiophenes, naturally occurring biocides, particularly against nematodes.The objective of the study described in this thesis was to use immobilized plant cells or large plant cell aggregates for secondary metabolite production. In particular the upscaling of immobilization techniques for plant cells, the role of diffusion limitation of oxygen as a substrate on the immobilized plant cells and its effect on secondary metabolite production of the immobilized plant cells were subject of research.A literature survey on immobilized plant cells is presented in Chapter 2. The advantages of immobilized plant cells, several aspects concerning immobilization techniques, consequences of plant cell immobilization, immobilized plant cell reactors, and future prospects of immobilized plant cells are discussed in this Chapter.Chapter 3 deals with the application of the resonance nozzle as an immobilization technique with a high production capacity for plant cells as well as yeast cells in calcium alginate gel beads. It is found that this technique has a production capacity of two orders of magnitude larger than the conventional dripping technique with a needle. The viability of the cells after immobilization with the resonance nozzle was preserved. An extension of the applicability of the nozzle technique for thermogelling gel supports (k-carrageenan, agar and gellan gum) Is described in Chapter 4. Plant cells, yeast cells, bacterial cells and insect cells were used as model systems in the experiments.In Chapter 5, the occurrence of oxygen diffusion limitation of Daucuscarota cells in agarose, calcium alginate and (κ-carrageenan, is determined by respiration measurements of the immobilized cells in order to explain the enhanced pronounced secondary metabolite production with alginate immobilized plant cells from in the literature reported experiments. However, in our experiments no differences between the support materials could be observed.The effective diffusion coefficient for oxygen (ID e ) in the gel material is an important factor in mathematical model calculations in order to quantify the occurrence of oxygen diffusion limitation. Chapter 6 deals with the experiments in which (ID e ) was determined in different gel materials (calcium alginate, κ-carrageenan, gellan gum, agar and agarose) by measuring the oxygen diffusion from a well- stirred solution into gel beads, which were initially free of oxygen. A mathematical model was fitted on the experimental data resulting in the value of (ID e ) which was used In the following experiments.In several parts of this thesis a mathematical model was used for calculation of oxygen concentration profiles in gel beads containing plant cells or cell aggregates in order to visualize the occurrence of oxygen diffusion limitation. In Chapter 7 this model is tested on validity by experimental measurement of the oxygen concentration profiles in agarose beads containing respiring plant cells of Tagetesminuta . This was done with the aid of an oxygen microelectrode with a tip of 15 μm. The experimental and calculated oxygen concentration profiles correspond quite well.Chapter 8 deals with the effects of aggregate size and oxygen diffusion limitation on thiophene production and cell growth by cell aggregates of Tagetespatula . It is concluded that aggregate size is related to thiophene production by the observation of an 'optimum' aggregate size where the production is highest. Calculations of the oxygen concentration profiles showed that this could be due to the absence of oxygen In the centre of the aggregates

Towards a concurrency theory for supervisory control

In this paper we propose a process-theoretic concurrency model to express supervisory control properties. In light of the present importance of reliable control software, the current work ow of direct conversion from informal specication documents to control software implementations can be improved. A separate modeling step in terms of controllable and uncontrollable behavior of the device under control is desired. We consider the control loop as a feedback model for supervisory control, in terms of the three distinct components of plant, requirements and supervisor. With respect to the control ow, we consider event-based models as well as state-based ones. We study the process theory TCP as a convenient modeling formalism that includes parallelism, iteration, communication features and non-determinism. Via structural operational semantics, we relate the terms in TCP to labeled transition systems. We consider the partial bisimulation preorder to express controllability that is better suited to handle non-determinism, compared to bisimulation-based models. It is shown how precongruence of partial bisimulation can be derived from the format of the deduction rules. The theory of TCP is studied under nite axiomatization for which soundness and ground-completeness (modulo iteration) is proved with respect to partial bisimulation. Language-based controllability, as the neccesary condition for event-based supervisory control is expressed in terms of partial bisimulation and we discuss several drawbacks of the strict event-based approach. Statebased control is considered under partial bisimulation as a dependable solution to address non-determinism. An appropriate renaming operator is introduced to address an issue in parallel communication. A case for automated guided vehicles (AGV) is modeled using the theory TCP. The latter theory is henceforth extended to include state-based valuations for which partial bisimulation and an axiomatization are dened. We consider an extended case on industrial printers to show the modeling abilities of this extended theory. In our concluding remarks, we sketch a future research path in terms of a new formal language for concurrent control modeling

Millimeter Wave Scattering from Neutral and Charged Water Droplets

We investigated 94GHz millimeter wave (MMW) scattering from neutral and charged water mist produced in the laboratory with an ultrasonic atomizer. Diffusion charging of the mist was accomplished with a negative ion generator (NIG). We observed increased forward and backscattering of MMW from charged mist, as compared to MMW scattering from an uncharged mist. In order to interpret the experimental results, we developed a model based on classical electrodynamics theory of scattering from a dielectric sphere with diffusion-deposited mobile surface charge. In this approach, scattering and extinction cross-sections are calculated for a charged Rayleigh particle with effective dielectric constant consisting of the volume dielectric function of the neutral sphere and surface dielectric function due to the oscillation of the surface charge in the presence of applied electric field. For small droplets with (radius smaller than 100nm), this model predicts increased MMW scattering from charged mist, which is qualitatively consistent with the experimental observations. The objective of this work is to develop indirect remote sensing of radioactive gases via their charging action on atmospheric humid air.Comment: 18 pages, 8 figure

Aberrant B cell receptor signaling in naïve B cells from patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and ultimately fatal disease in which an impaired healing response to recurrent micro-injuries is thought to lead to fibrosis. Recent findings hint at a role for B cells and autoimmunity in IPF pathogenesis. We previously reported that circulating B cells from a fraction of patients, compared with healthy controls, express increased levels of the signaling molecule Bruton’s tyrosine kinase (BTK). However, it remains unclear whether B cell receptor (BCR) signaling is altered in IPF. Here, we show that the response to BCR stimulation is enhanced in peripheral blood B cells from treatment-naïve IPF patients. We observed increased anti-immunoglobulin-induced phosphorylation of BTK and its substrate phospholipase Cγ2 (PLCγ2) in naïve but not in memory B cells of patients with IPF. In naïve B cells of IPF patients enhanced BCR signaling correlated with surface expression of transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) but not B cell activating factor receptor (BAFFR), both of which provide pro-survival signals. Interestingly, treatment of IPF patients with nintedanib, a tyrosine kinase inhibitor with anti-fibrotic and anti-inflammatory activity, induced substantial changes in BCR signaling. These findings support the involvement of B cells in IPF pathogenesis and suggest that targeting BCR signaling has potential value as a treatment option.</p

Tnfaip3 expression in pulmonary conventional type 1 Langerin‐expressing dendritic cells regulates T helper 2‐mediated airway inflammation in mice

BACKGROUND: Conventional type 1 dendritic cells (cDC1s) control antiviral and antitumor immunity by inducing antigen-specific cytotoxic CD8+ T-cell responses. Controversy exists whether cDC1s also control CD4+ T helper 2 (Th2) cell responses, since suppressive and activating roles have been reported. DC activation status, controlled by the transcription factor NF-κB, might determine the precise outcome of Th-cell differentiation upon encounter with cDC1s. To investigate the role of activated cDC1s in Th2-driven immune responses, pulmonary cDC1s were activated by targeted deletion of A20/Tnfaip3, a negative regulator of NF-κB signaling METHODS: To target pulmonary cDC1s, Cd207 (Langerin)-mediated excision of A20/Tnfaip3 was used, generating Tnfaip3fl/fl xCd207+/cre (Tnfaip3Lg-KO ) mice. Mice were exposed to house dust mite (HDM) to provoke Th2-mediated immune responses. RESULTS: Mice harboring Tnfaip3-deficient cDC1s did not develop Th2-driven eosinophilic airway inflammation upon HDM exposure, but rather showed elevated numbers of IFNγ-expressing CD8+ T-cells. In addition, Tnfaip3Lg-KO mice harbored increased numbers of IL-12-expressing cDC1s and elevated PD-L1 expression in all pulmonary DC subsets. Blocking either IL-12 or IFNγ in Tnfaip3Lg-KO mice restored Th2-responses, whereas administration of recombinant IFNγ during HDM sensitization in C57Bl/6 mice blocked Th2-development. CONCLUSIONS: These findings indicate that the activation status of cDC1s, shown by their specific expression of co-inhibitory molecules and cytokines, critically contributes to the development of Th2-cell-mediated disorders, most likely by influencing IFNγ production in CD8+ T-cells

Optical properties of dust

http://arxiv.org/abs/0808.4123Except in a few cases cosmic dust can be studied in situ or in terrestrial laboratories, essentially all of our information concerning the nature of cosmic dust depends upon its interaction with electromagnetic radiation. This chapter presents the theoretical basis for describing the optical properties of dust -- how it absorbs and scatters starlight and reradiates the absorbed energy at longer wavelengths.Partial support by a Chandra Theory program and HST Theory Programs is gratefully acknowledged

Clinical validation of an evidence-based method to adjust Pancreatic Enzyme Replacement Therapy through a prospective interventional study in paediatric patients with Cystic Fibrosis

Background A method to adjust Pancreatic Enzyme Replacement Therapy in Cystic Fibrosis is not currently available. Objectives To assess the in vivo efficacy of a method to adjust the dose of enzymatic supplement in CF extrapolated from previous in vitro digestion studies (theoretical optimal dose, TOD). Secondly, to assess how individual patient characteristics influence the expected coefficient of fat absorption (CFA) and thus to identify an individual correction factor to improve TOD. Methods A prospective interventional study in 43 paediatric patients with CF from 5 European centres. They followed a 24h fixed diet with the theoretical optimal dose for each meal. Faecal collection was carried out between colorimetric markers in order to include all the faeces corresponding to the fixed diet. Beta regression models were applied to assess the associations of individual patient characteristics with the CFA. Results Median CFA was 90% (84, 94% 1st, 3rd Q.) with no significant differences among centres. Intestinal transit time was positively associated with CFA (p = 0.007), but no statistical associations were found with and age, gender, phenotype or BMI. Regression model showed no improvement of the in vitro predicted theoretical optimal dose when taking individual patient characteristics into account. Conclusion Strict adherence to the theoretical optimal dose of enzymatic supplement for a prescribed meal, led to median CFA levels at the clinical target of 90% with a low variability between patients. The proposed method can be considered as a first approach for an evidencebased method in PERT dosing based on food characteristics. Results have to be confirmed in free dietary settings