Spi1 R235C point mutation confers hypersensitivity to radiation-induced acute myeloid leukemia in mice

Ionizing radiation (IR) is a risk factor for acute myeloid leukemia (rAML). Murine rAMLs feature both hemizygous chromosome 2 deletions (Del2) and point mutations (R235) within the hematopoietic regulatory gene Spi1. We generated a heterozygous CBA Spi1 R235 mouse (CBASpm/+) which develops de novo AML with 100% incidence by ∼12 months old and shows a dose-dependent reduction in latency following X-irradiation. These effects are reduced on an AML-resistant C57Bl6 genetic background. CBASpm/Gfp reporter mice show increased Gfp expression, indicating compensation for Spm-induced Spi1 haploinsufficiency. Del2 is always detected in both de novo and rAMLs, indicating that biallelic Spi1 mutation is required for AML. CBASpm/+ mice show that a single Spm modification is sufficient for initiating AML development with complete penetrance, via the "two-hit" mechanism and this is accelerated by IR exposure. Similar SPI1/PU.1 polymorphisms in humans could potentially lead to enhanced susceptibility to IR following medical or environmental exposure.

Yersinia ruckeri infection activates local skin and gill B cell responses in rainbow trout

Teleost fish lack organized structures in mucosal tissues such as those of mammals, but instead contain dispersed B and T cells with the capacity to respond to external stimuli. Nonetheless, there is still a great lack of knowledge regarding how B cells differentiate to plasmablasts/plasma cells in these mucosal surfaces. To contribute to a further understanding of the mechanisms through which fish mucosal B cells are activated, in the current study, we have studied the B cell responses in the skin and gills of rainbow trout (Oncorhynchus mykiss) exposed to Yersinia ruckeri. We have first analyzed the transcription levels of genes related to B cell function in both mucosal surfaces, and in spleen and kidney for comparative purposes. In a second experiment, we have evaluated how the infection affects the presence and size of B cells in both skin and gills, as well as the presence of plasmablasts secreting total or specific IgMs. The results obtained in both experiments support the local differentiation of B cells to plasmablasts/plasma cells in the skin and gills of rainbow trout in response to Y. ruckeri. Interestingly, these plasmablasts/plasma cells were shown to secrete specific IgMs as soon as 5 days after the exposure. These findings contribute to a further understanding of how B cells in the periphery respond to immune stimulation in teleost fish.

A review of the biological and clinical implications of RAS-MAPK pathway alterations in neuroblastoma

Neuroblastoma is the most common extra-cranial solid tumor in children, representing approximately 8% of all malignant childhood tumors and 15% of pediatric cancer-related deaths. Recent sequencing and transcriptomics studies have demonstrated the RAS-MAPK pathway’s contribution to the development and progression of neuroblastoma. This review compiles up-to-date evidence of this pathway’s involvement in neuroblastoma. We discuss the RAS-MAPK pathway’s general functioning, the clinical implications of its deregulation in neuroblastoma, and current promising therapeutics targeting proteins involved in signaling.

Rôle de l’infirmière et du cadre infirmier lors de la mise en place urgente d’une équipe de dépistage autour d’un cluster de coronavirus

Introduction

La découverte d’un cluster autour d’un cas d’infection à coronavirus Covid-19 dans une commune française a déclenché la création d’une cellule de crise. Une équipe d’intervention a dû être constituée 24 h après cette découverte pour dépister les contacts d’un enfant infecté appartenant à ce cluster. Celle ci était composée d’une équipe médicale et paramédicale d’infectiologie, d’un médecin et d’ambulanciers du SAMU. L’objet de ce travail est de décrire le rôle des paramédicaux lors de la préparation et de la réalisation du dépistage autour des cas.

Matériels et méthodes

Il est décrit l’action du cadre infirmier et de l’équipe infirmière lors de la création d’une équipe de dépistage en urgence autour d’un cluster de coronavirus et la gestion de l’accueil des cas possibles en hospitalisation.

Résultats

L’intervention nécessitait la mobilisation, en moins de 24 h, d’une équipe afin de dépister 100 enfants des écoles fréquentées par l’enfant infecté. Une première équipe comprenant médecins, infirmiers, cadres infirmiers et ambulanciers était chargée du dépistage dans la commune du cas. La réactivité de l’équipe paramédicale a été permise par l’implication dès la découverte du cluster du cadre soignant du service. Celui-ci a été impliqué dans la cellule de crise, puis s’est déplacé sur la commune concernée pour l’organisation et la réalisation des premiers prélèvements du cluster. Fort de cette expérience, le cadre a pu, 24 h après, coordonner la préparation du matériel, le circuit des cas contacts et le protocole des règles d’hygiène et de prélèvements. Sur la base du volontariat, 5 infirmières de l’équipe d’infectiologie, un cadre et 2 infirmiers du SAMU ont participé à l’action de terrain en plus du cadre d’infectiologie. Ceci a permis la création de 6 postes de prélèvements en coopération avec les médecins infectiologues. Dans l’hypothèse d’hospitalisation des cas possibles, il a été nécessaire d’organiser en parallèle un cohorting dédié au coronavirus dans le service de maladies Infectieuses du centre hospitalier de référence. Celui-ci a été coordonné par le cadre soignant avec les médecins infectiologues restés en lien avec la cellule de crise. Le transfert de la moitié des patients alors hospitalisés dans le service a été réalisé. Un protocole de libération de la totalité des lits du service a été rédigé par anticipation.

Conclusion

Cette expérience montre la capacité de mobilisation très rapide d’une équipe paramédicale pour mettre en place une intervention de dépistage délocalisée face à un risque épidémique. La bonne gestion de la crise a été permise par l’anticipation, la réactivité, l’expérience et la compétence en hygiène des acteurs paramédicaux.

P3116New role of EPAC1 in Anthracycline-induced cardiotoxicity and anticancer therapy

Introduction

Doxorubicin (Dox) is an anthracycline commonly used to treat many types of cancer; unfortunately this chemotherapeutic agent induces many side effects such as cardiotoxicity leading to dilated cardiomyopathy (DCM). The cardiotoxicity of Dox has been related to reactive oxygen species generation, DNA intercalation, topoisomerase II inhibition and bioenergetics alterations leading to cardiomyocyte death.

Objective

Nowadays the challenge is to find new treatment options aiming at reducing Dox cardiotoxicity. Epac (exchange protein directly activated by cAMP) signaling could be worth investigating as Epac activates small G proteins which are known to be involved in Dox-induced cardiotoxicity.

Methods

We investigated the time/dose-dependent Dox effect on Epac signaling in both in vivo mice model (C57Bl63/ Knock-out Epac1 mice, iv injections, 12mg/kg cumulative dose) and in vitro (primary culture of neonatal rat cardiomyocytes (NRVM, 24h, Dox 1μM).

Results

In vivo, Dox-treated mice developed a DCM associated with Ca2+ homeostasis dysfunction (increase of Ca2+ waves and Ca2+ leaks). In vitro, as measured by flow cytometry and western blot, Dox (1μM) induced DNA damages and cell death in NRVM. This cell death is associated with apoptotic features including mitochondrial membrane permeabilization, caspase activation and cell size reduction. The inhibition of Epac1 (ESI09, CE3F4) decreased Dox-induced DNA damage, loss of mitochondrial membrane potential, apoptosis and finally cardiomyocyte death. Moreover, in vivo, Epac1 KO mice were protected against Dox-induced cardiotoxicity by unaltered cardiac function (no DCM) and calcium homeostasis at 15 weeks post-treatment.

Conclusion

Inhibition of Epac1 could be a valuable therapeutic strategy to limit Dox-induced cardiomyopathy during cancer chemotherapy. Indeed, preliminary data show also that preventing Dox-induced cardiotoxicity, the inhibition of Epac1 can also potentiate cancerous cells death.

Acknowledgement/Funding

Labex Lermit (ANR 0033), Torino and Inserm

Atrial fibrillation is associated with hypermethylation in human left atrium, and treatment with decitabine reduces atrial tachyarrhythmias in spontaneously hypertensive rats

Atrial fibrillation (AF) is the most common cardiac arrhythmia. As the molecular mechanisms underlying the pathology are largely unknown, this cardiac arrhythmia remains difficult to treat. To identify specific molecular actors involved in AF, we have performed a transcriptomic analysis on left atrium (LA) from patients with valvular heart disease with or without AF. We showed that 1627 genes had altered basal expression level in LA tissue of AF patients compared with the control group. The significantly enriched gene ontology biological process "anatomical structure morphogenesis" contained the highest number of genes in line with changes in structure that occur when the human heart remodels following AF development (ie, LA dilatation and interstitial fibrosis). We then focused the study on Pitx2 (paired-like homeodomain 2), being the most altered transcription factor in LA from AF patients and from which compelling evidence have indicated that its reduced expression can be considered as a marker for the disease. In addition, its expression was inversely correlated with LA size. We demonstrated that AF is associated with Pitx2 promoter hypermethylation both in humans and arrhythmic aging spontaneously hypertensive rats. Chronic administration of a DNA methylation inhibitor (ie, 5-Aza-2'-deoxycitidine) improved ECG arrhythmic profiles and superoxide dismutase activities and reduced fibrosis in the left ventricle of spontaneously hypertensive rats. Taken together, these data support the notion that AF is associated with epigenetic changes in LA and provide a proof-of-concept that hypomethylating agents have to be considered in the treatment of atrial arrhythmias.

Molecular Mechanisms of Noncanonical Autophagy

Macroautophagy is a lysosomal catabolic process that maintains the homeostasis of eukaryotic cells, tissues, and organisms. Macroautophagy plays important physiological roles during development and aging processes and also contributes to immune responses. The process of macroautophagy is compromised in diseases, such as cancer, neurodegenerative disorders, and diabetes. The autophagosome, the double-membrane-bound organelle that sequesters cytoplasmic material to initiate macroautophagy, is formed by the hierarchical recruitment of about 15 autophagy-related (ATG) proteins and associated proteins, such as DFCP1, AMBRA1, the class III phosphatidyl-inositol 3-kinase VPS34, and p150/VPS15. Evidence suggests that in addition to the canonical pathway, noncanonical pathways that do not require the entire repertoire of ATGs can also result in formation of autophagosomes. Here we will discuss recent discoveries concerning the molecular regulation of these noncanonical forms of macroautophagy and their potential roles in cellular responses to stressful situations.

Motor function levels and pelvic parameters in walking or ambulating children with cerebral palsy

BACKGROUND

In children with cerebral palsy, spinal equilibrium and pelvic strategies may vary according to the functional status.

OBJECTIVES

To study the relationship between motor function and pelvic and spinal parameters in a population of children and adolescents with cerebral palsy (rated from level I to level IV on Gross Motor Function Classification System [GMFCS]). A sagittal X-ray of the spine in the standing position was analyzed with Optispine(®) software.

RESULTS

The study population comprised 114 children and adolescents (mean [range] age: 12.35 [4-17]). For the study population as a whole, there were significant overall correlations between the GMFCS level on one hand and pelvic incidence and pelvic tilt (PT) on the other (P=0.013 and 0.021, respectively).

DISCUSSION

Pelvic parameters vary according to the GMFCS level but do not appear to affect spinal curvature. The sacrum is positioned in front of the head of the femur (i.e. negative PT) in GMFCS level I and progressively moves backwards (i.e. positive PT) in GMFCS levels II, III and IV.

First Report of Umbel Browning and Stem Necrosis Caused by Diaporthe angelicae on Carrot in France

In 2011, carrot (Daucus carota L.) seed production occurred on 2,900 ha, which accounts for approximately 25% of the area devoted to the production of vegetable fine seeds. Since 2007, symptoms of umbel browning have been regularly observed in carrot production areas located in the central region. Initially, triangular necrotic lesions appeared on carrot umbels that later spread to the entire umbels and often progressed to the stems. Diseased umbels became dried prematurely, compromising seed development. The loss in seed production was estimated at approximately 8% of the harvested carrot umbels during the cropping seasons of spring and summer 2007 and 2008 in France. In collaboration with seed companies, diseased carrot stems were collected from seven fields of seed production (eight plants per field) and a fungus was isolated from the tissue. The cultures were grown on malt (2%) agar (1.5%) medium and incubated for 2 weeks at 22°C in darkness. Young fungal colonies were white and a brownish green pigmentation developed when the colonies became older. The same color was observed from the top and on the reverse of the colonies. To induce sporulation, isolates were grown on water agar (1.5%) medium in the presence of carrot stem fragments for 1 week at 22°C in darkness, followed by 1 week at 22°C in white light under a 16-h photoperiod. Pycnidia were produced on stem fragments and contained alpha and beta conidia typical of the genus Diaporthe (2). Alternatively, pycnidia were also obtained on malt agar medium after 2 weeks of culture at 25°C in white light under a 12-h photoperiod. The size of alpha and beta conidia was 6.3 ± 0.5 × 2.3 ± 0.4 μm and 23.3 ± 1.8 × 0.9 ± 0.2 μm, respectively (n = 170). In order to confirm the identification at the genus level and determine the species, DNA was extracted from the mycelium of three representative isolates and the ITS regions of the ribosomal DNA were amplified using universal primers (1). The sequences of the amplified products (GenBank Accession Nos. KF240772 to KF240774) were 100% identical with the ITS sequence of a Diaporthe angelicae isolate deposited in the NCBI database (CBS 111592 isolate, KC343027). To confirm pathogenicity, the three isolates of D. angelicae were inoculated on carrot umbels in the greenhouse. A total of nine plants were inoculated (three plants per isolate). Using a micropipette, 10 μl of a conidial suspension containing alpha and beta conidia (10⁵ conidia mL^-1) were deposited at the base of the primary umbel and two secondary umbels, which were wounded before inoculation using a scalpel blade. Seven inoculated plants developed triangular, necrotic lesions that were typical umbel browning. D. angelicae was re-isolated on malt agar medium from the inoculated diseased carrot umbels. To our knowledge, this is the first report of D. angelicae in carrot cultivated for seed production in France. The disease resembles the lesions described in the Netherlands in 1951 on carrot inflorescence caused by Phomopsis dauci (3). In future experiments, it would be crucial to precisely determine if D. angelicae could be transmitted to the seeds. References: (1) M. A. Innis et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (2) J. M. Santos and A. J. L. Philips. Fungal Divers. 34:111, 2009. (3) J. A. von Arx. Eur. J. Plant Pathol. 57:44, 1951.

Sagittal X-ray parameters in walking or ambulating children with cerebral palsy

Adolescents with cerebral palsy (CP) who walk or ambulate often have an abnormal clinical and radiological spinal profile during pubertal growth compared with adolescents of the same age without neuromotor impairments. Therefore, in the following study, we aimed to conduct a radiological assessment of static data on the lumbar-pelvic-femoral complex in ambulatory children with CP to compare these data with those of an asymptomatic population. The CP population was comprised of 119 children and the asymptomatic population was comprised of 652 children. The large format (30×90cm) sagittal X-rays were taken while subjects were in a comfortable position in which knees and hips were in maximal extension. Analyses were performed using Optispine(®) software to measure the parameters of an X-ray of the profile of the spine, pelvis and femurs. Comparing, the two populations, we found no difference in the shape parameter (pelvic incidence) but we did find significant differences in the positional parameters (pelvic tilt and sacral slope) of the pelvis. We found a difference in the curvature and orientation of lumbar lordosis as well as in the number of vertebrae involved in the kyphosis and its orientation. There was also a significant difference in the C7 plumb line. We can say that the CP population is not structurally different from the control population, but that parameters become disturbed during growth. These disturbances should be identified and monitored so that changes can be detected early and progression can be prevented.

Expression of α-defensin 1-3 in T cells from severe cutaneous drug-induced hypersensitivity reactions

BACKGROUND

Cytotoxic T cells seem to be the main effector cells in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). However, recent data support a role of the innate immune system in the etiopathology of drug-induced cutaneous reactions. In this study, we analyzed the expression of α-defensins 1-3 in mononuclear cells from patients with SJS/TEN, drug-induced maculopapular exanthema (MPE), and healthy donors.

METHODS

DEFA1A3 gene expression was analyzed by quantitative and end-point RT-PCR. Intracellular flow cytometry, immunofluorescence and immunohistochemistry were carried out to verify α-defensin 1-3 protein expression in mononuclear cells from peripheral blood and skin infiltrates. α-Defensin 1-3 concentration was evaluated in plasma and blister fluid samples by ELISA.

RESULTS

We herein describe DEFA1A3 gene expression in peripheral blood mononuclear cells (PBMCs) from patients with drug-induced cutaneous diseases. Gene expression analysis unveiled transcription in CD4 and CD8 peripheral blood T cells. Protein expression was confirmed by intracellular flow cytometry in mononuclear cells from the patients, including monocytes, NK cells, and T cells from peripheral blood and blister fluid. Further analysis of protein content by flow cytometry revealed higher protein levels in CD56(+) CD3(+) lymphocytes from patients with SJS/TEN when compared to MPE and healthy donors. Immunohistological analysis was used to confirm expression in dermal infiltrates. α-Defensin levels were estimated by ELISA to be 3- to 175-fold higher in blister fluid when compared to simultaneously drawn plasma samples.

CONCLUSION

Upregulation of innate immune molecules such as α-defensins 1-3 in T cells from patients with SJS/TEN may be involved in the etiopathology of these life-threatening diseases induced by medications.

Thoracolumbar junction lateral spine dislocation

The authors describe a case of traumatic lateral spine dislocation at the thoracolumbar junction level, without fracture, in a healthy young adult, complicated by a complete neurological deficit. The main aspects of surgical management are discussed based on a review of the literature. Control of the spinal cord is a mandatory first step, before reduction, independently of neurological deficits considerations. Instrumented stabilization and fusion are achieved thereafter; levels selection for instrumentation and fusion depends on the injury location.

Acute generalized exanthematous pustulosis due to tetrazepam

Tetrazepam is a benzodiazepine that is widely used in Spain as a muscle relaxant, with occasional cutaneous side effects. We report a patient who developed a generalized pruriginous cutaneous reaction compatible with acute generalized exanthematous pustulosis (AGEP) due to tetrazepam. Patch tests with bromazepam, diazepam, and tetrazepam were negative at 48 and 72 hours; however, the tetrazepam patch showed a positive reaction at 10 days. Immunohistochemical studies revealed a mononuclear infiltrate composed of CD4+ and CD8+ T lymphocytes. Analysis of interleukin (IL) 8 expression by quantitative polymerase chain reaction revealed increased IL-8 mRNA levels in patch test-positive skin. Lymphoblast transformation test (LTT) was positive with tetrazepam but not with diazepam. Positive patch test and LTT suggested that tetrazepam-specific lymphocytes might be responsible for a T cell-mediated reaction. These results support previous data suggesting an important role for IL-8 and drug-specific T cells in the pathogenesis ofAGEP and imply that the reaction was specific to tetrazepam with no cross-reactivity to other benzodiazepines.

[Superior mesenteric artery syndrome following correction of spinal deformity: case report and review of the literature]

Superior mesenteric artery syndrome is a rare complication which can develop after surgical correction of a spinal deformity. The syndrome is caused by an extrinsic compression on the third portion of the duodenum by the aorta posteriorly and the mesenteric artery anteriorly. We report here a case of aortomesenteric compression of the duodenum secondary to surgical correction of lower thoracic scoliosis in a 19-year-old female. The patient presented vomiting and intestinal obstruction ten days after spinal surgery. Treatment consisted in exclusive parenteral nutrition followed by careful surveillance and progressive reintroduction of oral food intake to avoid unnecessary surgery. Young thin subjects are predominantly exposed to this type of complication. The body mass index is a good indication to identify subjects at risk. Symptoms of upper gastrointestinal obstruction develop seven to ten days after surgery. Diagnosis is based on transit studies using a hydroluble contrast agent which reveals major gastric dilation and a clear interruption of the transit at the level of the third duodenum as well as retrograde peristaltism. Medical treatment should be undertaken first and is effective in the large majority of cases. Surgery may be proposed only in the event of failure. Recurrence is exceptional. Early diagnosis, delivery of clear information for the patient and family and multidisciplinary management are important points to consider for proper care for this complication which if neglected can become life-threatening.

Up-regulation of CCL17, CCL22 and CCR4 in drug-induced maculopapular exanthema

BACKGROUND

Maculopapular exanthema has been reported to be the most frequently drug-induced cutaneous reaction. Although T lymphocytes are involved in the pathomechanism of this disease, little is know about the recruitment of these cells to the skin.

OBJECTIVE

The aim of this work is to study the role of the chemokines TARC/CCL17 and MDC/CCL22 in the lymphocyte trafficking to affected skin in drug-induced exanthemas.

METHODS

Real-time PCR was performed to quantify gene expression levels of CCL17, CCL22 and their receptor CCR4 in lesional skin biopsies and in peripheral blood mononuclear cells from patients. CCL27 and CCL22 proteins were detected in the skin by immunochemistry. Protein expression of CCR4 was determined by flow cytometry in peripheral blood lymphocytes. Functional migration assays to CCL17 and CCL22 were assessed to compare the migratory responses of peripheral blood lymphocytes from patients and healthy subjects.

RESULTS

CCL17 and CCL22 were up-regulated in maculopapular exanthema-affected skin. CCR4 mRNA levels and protein expression were increased in peripheral blood mononuclear cells during the acute phase of the disease. The increased expression of the receptor was consistent with a higher response of peripheral blood lymphocytes to CCL17 and CCL22 compared with the migratory response in healthy donors.

CONCLUSION

TARC/CCL17 and MDC/CCL22 might cooperate in attracting T lymphocytes to skin in drug-induced maculopapular exanthemas.

Amoxicillin conjugates to HLA class I molecules and interferes with signalling through the ILT2/LIR-1/CD85j inhibitory receptor

BACKGROUND

Drugs behave as haptens and are recognized by specific T-cell receptors in the context of major histocompatibility complex (MHC) molecules in allergic subjects. Natural killer cell receptors (NKRs) are MHC class I-specific receptors that modulate the threshold of activation of immunocompetent cells. Amongst them, ILT2/LIR-1/CD85j is an inhibitory NKR widely distributed in several cell lineages and with a broad spectrum of recognition of human leucocyte antigen (HLA) class I ligands.

METHODS

We have evaluated, at the biochemical and cellular level, the ability of amoxicillin (AX) conjugate to HLA class I molecules and to interfere with the inhibitory signal delivered by the HLA class I receptor ILT2/LIR-1/CD85j.

RESULTS

We have detected AX bound to cell membrane proteins and in particular to HLA class I molecules. Preincubation with AX rendered target cells susceptible to NK cell-mediated lysis. In conjugation experiments, target cell-bound AX hampered tyrosine phosphorylation of ILT2/LIR-1/CD85j upon ligand recognition and the subsequent recruitment of SHP-1 phosphatase.

CONCLUSION

Conjugation of AX to HLA class I molecules may mask HLA recognition by inhibitory receptors and attenuate the negative signal delivered by SHP-1 phosphatase, thus lowering the threshold of activation of effector cells.

[Sagittal balance of the spine and degenerative spondylolisthesis]

PURPOSE OF THE STUDY

Several reports have examined the pathophysiology of degenerative spondylolisthesis. Very little work has however been devoted to the influence of spinal balance in the sagittal plane in its pathogenesis. The purpose of this work was to present a descriptive analysis of pelvic and spinal sagittal balance in a cohort of seventy patients treated for degenerative spondylolisthesis and to compare findings with those established in a population of 250 volunteers. The goal was to deduct pathophysiological hypotheses and identify therapeutic implications.

MATERIAL AND METHODS

Seventy patients were included in this study. The following variables were noted: pelvic incidence and version, sacral slope, lumbar lordosis, thoracic kyphosis, T9 sagittal tilt and S1-S2 angle. These variables were measured on digitalized lateral views of the spine using a dedicated software (SpineView). Univariate analysis of the values obtained was performed to identify the variable distributions. Multivariate analysis was applied to study the relationships between these variables and to better define perturbations of spinal balance in the anteroposterior plane. The findings were compared with those obtained in a control population.

RESULTS

One of the essential characteristics of the cohort of patients with degenerative spondylolisthesis was the presence of an exaggerated pelvic incidence (62.6 degrees versus 54.7 degrees in the control population). The most significant determinants of T9 sagittal tilt (which reflects sagittal balance) were: pelvic version, pelvic incidence, lumbar lordosis, and L4-S1 local lordosis. One-third of our patients presented posterior tilt due to exaggerated thoracic kyphosis. The high pelvic incidence, via hyperlordosis and increased pelvic version, could be one of the factors favoring degenerative disease of the spinal unit.

CONCLUSIONS

This work enabled us to better describe sagittal balance in patients with degenerative spondylolisthesis and to propose hypotheses concerning the underlying mechanism of progressive degeneration. We emphasize the diversity of spinal balance in these patients and the different therapeutic implications.

On-line estimation of kinetic parameters in anaerobic digestion using observer-based estimators and multiwavelength fluorometry

Observer-based estimators (OBE) were used for estimation of state variables and kinetic parameters in an anaerobic digestion (AD) process. A simplified first-order model with time-varying kinetic parameters was used to design an OBE for kinetic parameter estimation. This approach was validated on a laboratory-scale anaerobic reactor equipped with a multiwavelength fluorometer for on-line measurements of COD and VFA concentrations in the reactor effluent. The proposed estimators provide continuous adjustment of kinetic parameters and can be used for predictions of state variables between samples acquisition and during sensor failure.

ADM1 application for tuning and performance analysis of a multi-model observer-based estimator

Anaerobic digestion model no.1 (ADM1) was used for tuning and performance analysis of the multi-model observer based estimator (mmOBE). The mmOBE was based on the variable structure model (VSM) of the anaerobic digestion model, which consists of several local submodels, each of which describes a typical process state. Depending on the hydraulic retention time, ADM1 simulated the methanogenic, organic overload, and acidogenic states of the process. These simulations allowed for optimising tunable parameters of the mmOBE. Owing to relatively slow process dynamics, a data acquisition interval as large as one day was sufficient to obtain acceptable accuracy. The simulations of mmOBE performance showed excellent rate of mmOBE convergence to ADM1 outputs. Moreover, mmOBE successfully estimated key kinetic parameters, such as maximal transformation rates of CODs, VFAs, and methane. These estimations can be used in the development of the advanced knowledge-based process system, which uses both available measurements and estimations of key kinetic parameters for extended diagnosis of failures and process trend analysis.

Multi-wavelength fluorometry for anaerobic digestion process monitoring

Applicability of multi-wavelength fluorometry for anaerobic digestion process monitoring was investigated in a 3.5 L upflow anaerobic sludge bed (UASB) lab-scale reactor. Both off-line and on-line monitoring of key process parameters was tested. Off-line emission spectra were measured at an angle of 90 degrees to the excitation beam using a cuvette. On-line measurements were carried out using a fiber optic probe in the external recirculation line of the digester. Fluorescence spectra were correlated to available analytical measurements to obtain partial least square regression models. An independent set of measurements was used to validate the regression models. Model estimations showed reasonable agreement with analytical measurements with multiple determination coefficients (R2) between 0.6 and 0.95. Results showed that offline fluorescence measurements can be used for fast estimation of anaerobic digestor effluent quality. At the same time, the on-line implementation of multi-wavelength fluorescence measurements can be used for realtime process monitoring and, potentially, for on-line process control.

Application of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process

This work examined the use of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process. Experiments were carried out in a laboratory-scale anaerobic digestor fed with either synthetic or agricultural (cheese factory) wastewater. An in-line fiber optic probe installed in the external recirculation loop of the reactor was used to acquire fluorescence spectra with an interval of 5-10 min. The spectra were compared with analytical measurements taken at the same time to develop regression models, which were then used to predict concentrations of chemical oxygen demand, volatile fatty acids, and other key process parameters. A comparison of partial least squares (PLS), nonlinear principal components regression, and step-wise regression models on an independent set of data showed that the PLS model gave the best prediction accuracy.

Effect of radiation on cAMP, cGMP and Ca(2+)(i) pathways and their interactions in rat distal colon

The secretory response implicated in the intestinal response to luminal attack is altered by radiation. The cAMP, cGMP and Ca(2+)(i) pathways leading to secretion as well as the interactions between the cAMP pathway and the cGMP or Ca(2+)(i) pathway were studied in the rat distal colon 4 days after a 9-Gy abdominal X irradiation, when modifications mainly occurred. The secretory response in Ussing chambers and cAMP and cGMP accumulation in single isolated crypts were measured. The muscarinic receptor characteristics were determined in mucosal membrane preparations. The secretory response by the cAMP pathway (stimulated by vasoactive intestinal peptide or forskolin) and the cAMP accumulation in crypts were decreased (P < 0.05) after irradiation. The weak secretory response induced by the cGMP pathway (stimulated by nitric oxide or guanylin) was unaltered by radiation, and the small amount of cGMP determined in isolated crypts from the control group became undetectable in the irradiated group. Inducible NOS was not involved in the hyporesponsiveness to VIP after irradiation (there was no effect of an iNOS inhibitor). The secretory response by the Ca(2+)(i) pathway (stimulated by carbachol) was unaffected despite a decreased number and increased affinity of muscarinic receptors. The non-additivity of VIP and carbachol co-stimulated responses was unmodified. In contrast, VIP and SNP co-stimulation showed that NO enhanced the radiation-induced hyporesponsiveness to VIP through a reduced accumulation of cAMP in crypts. This study provides further understanding of the effect of ionizing radiation on the intracellular signaling pathways.

Application of a variable structure model in observation and control of an anaerobic digestor

In this work, a variable structure model (VSM) of an anaerobic digestion process was developed. The anaerobic biodegradation process was described by four nonlinear submodels representing methanogenic, chemical oxygen demand overload, acidogenic, and hydrogen-inhibited states of the anaerobic process. At any instant, process dynamics was modeled only by one of the submodels, while the others were considered trailing. The choice of a leading submodel was handled by a knowledge-based system, which analyzed available process variables, such as off-gas composition and reactor pH. The feasibility of the proposed method was demonstrated both by using the VSM to predict the outputs of a comprehensive process model, and the experimental results obtained in a pilot scale anaerobic fixed-bed bioreactor.

Alterations of the VIP-stimulated cAMP pathway in rat distal colon after abdominal irradiation

Ionizing radiation induces hyporesponsiveness of rat colonic mucosa to vasoactive intestinal peptide (VIP). Possible mechanisms responsible for this hyporesponsiveness of the cAMP communication pathway in rat colon were investigated. VIP- and forskolin-stimulated short-circuit current (I(sc)) responses were studied after a 10-Gy abdominal irradiation in Ussing chambers as well as in single, isolated crypts. Adenylyl cyclase (AC) activity and VIP receptor characteristics were determined in mucosal membrane preparations. In addition, alterations in crypt morphology were studied. Impaired secretory responses to VIP and forskolin were observed 4 days after irradiation (decrease of 80%). cAMP analog-stimulated I(sc) responses were unchanged. In isolated crypts, VIP- and forskolin-stimulated cAMP accumulation was markedly reduced by 80 and 50%, respectively. VIP-stimulated AC activity and VIP receptor number were decreased in membrane preparations. No major change of cellularity was associated with these functional alterations. In conclusion, the decreased secretory responses to VIP of rat colon are associated with reduced cAMP accumulation, decreased AC activity, and diminution of VIP receptor numbers without a marked decrease of crypt cell number.

Characterization of altered absorptive and secretory functions in the rat colon after abdominal irradiation: comparison with the effects of total-body irradiation

The aim of this work was to determine the alterations in the absorptive and secretory functions of the rat colon after abdominal irradiation and to compare the effects of abdominal and whole-body irradiation. Rats received an abdominal irradiation with 8 to 12 Gy and were studied at 1, 4 and 7 days after exposure. Water and electrolyte absorption was measured in vivo by insertion of an agarose cylinder into the colons of anesthetized rats. In vitro measurements of potential difference, short-circuit current and tissue conductance were performed in Ussing chambers under basal and agonist-stimulated conditions. Most of the changes appeared at 4 days after abdominal irradiation. At this time, a decrease in water and electrolyte absorption in the colon was observed for radiation doses > or = 9 Gy. The response to secretagogues (VIP, 5-HT and forskolin) was attenuated after 10 and 12 Gy. Epithelial integrity, estimated by potential difference and tissue conductance, was altered from 1 to 7 days after 12 Gy abdominal irradiation. These results show that the function of the colon was affected by abdominal irradiation. Comparison with earlier results for total-body irradiation demonstrated a difference of 2 Gy in the radiation dose needed to induce changes in the function of the colon.

Effect of an alpha-linolenic acid-rich diet on rat mammary tumor growth depends on the dietary oxidative status

To investigate whether the oxidative status of an 18:3(n-3) polyunsaturated fatty acid (PUFA)-enriched diet could modulate the growth of chemically induced rat mammary tumors, three independent experiments were performed. Experiments I and II examined the variation of tumor growth by addition of antioxidant (vitamin E) or a prooxidant system (sodium ascorbate/2-methyl-1,4-naphthoquinone) to a 15% linseed oil diet rich in 18:3(n-3). Experiment III addressed the role of PUFA in the tumor growth modulation by vitamin E. For this purpose, we compared the effect of vitamin E in 15% fat diets containing a high level of 18:3(n-3) (linseed oil, high-PUFA diet) or devoid of 18:3(n-3) (hydrogenated palm/sunflower oil, low-PUFA diet). In Experiments I-III, tumor growth increased in the presence of vitamin E compared with control (without vitamin E). Furthermore, it decreased when prooxidant was added. In contrast, no difference was observed when the diet was low in PUFA, suggesting that sensitivity of PUFA to peroxidation may interfere with tumor growth. This observation was supported by growth kinetic parameter analysis, which indicated that tumor growth resulted from variations in cell loss but not from changes in cell proliferation. These data show that, in vivo, PUFA effects on tumor growth are highly dependent on diet oxidative status.

Metabolic capacity for L-citrulline synthesis from ammonia in rat isolated colonocytes

Ammonia is present at high concentration in the colon lumen and is considered a colon cancer suspect. Furthermore, ammonia usually eliminated by the liver in the ornithine cycle is considered highly toxic to cerebral function when present in excess in the blood plasma. Therefore, the metabolic pathways involved in ammonia metabolism in colonocytes were studied in the present study. Rat colonocytes were found equipped with low carbamoylphosphate synthase I activity, high ornithine carbamoyltransferase and arginase activities and low argininosuccinate synthase activity. High (10 and 50 mmol/l) NH4Cl concentrations but not low concentrations (1 and 5 mmol/l) were found able to increase respectively 3- and 10-fold the conversion of radioactive L-arginine to L-citrulline. In contrast, very low capacity for L-citrulline conversion to L-arginine is found in colonocytes. It is concluded that an incomplete ornithine cycle is operative in colonocytes which results in ammonia stimulated L-citrulline production. The contribution of this metabolic pathway in relation to ammonia detoxication by colonocytes is discussed.