Volitional assessment of respiratory muscle strength.

Respiratory muscle weakness may induce dyspnoea, secretion retention and respiratory failure. Assessing respiratory muscle strength is mandatory in neuromuscular diseases and in case of unexplained dyspnoea. A step by step approach is recommended, starting with simple volitional tests. Using spirometry, respiratory muscle weakness may be suspected on the basis of an abnormal flow-volume loop or a fall of supine vital capacity. When normal, maximal inspiratory and expiratory pressures against a near complete occlusion exclude significant muscle weakness, but low values are more difficult to interpret. Sniff nasal inspiratory pressure is a useful alternative because it is easy and it eliminates the problem of air leaks around the mouthpiece in patients with neuromuscular disorders. The strength available for coughing is easily assessed by measuring peak cough flow. In most cases, these simple non invasive tests are sufficient to confirm or to eliminate significant respiratory muscle weakness and help the timely introduction of ventilatory support or assisted cough techniques. In a minority of patients, a more complete evaluation is necessary using non volitional tests like cervical magnetic stimulation of phrenic nerves.

Evaluation of respiratory and dermal occupational exposures to monoethanolamine during cleaning

Professional cleaning is a basic service occupation with a wide variety of tasks carried out in all kind of different sectors and workplaces by a large workforce. One important risk for cleaning workers is the exposure to chemical substances that are present in cleaning products.Monoethanolamine was found to be often present in cleaning products such as general purpose cleaners, bathroom cleaners, floor cleaners and kitchen cleaners. Monoethanolamine can injure the skin, and exposure to monoethanolamine was associated to asthma even when the air concentrations were low. It is a strong irritant and known to be involved in sensitizing mechanisms. It is very likely that the use of cleaning products containing monoethanolamine gives rise to respiratory and dermal exposures. Therefore there is a need to further investigate the exposures to monoethanolamine for both, respiratory and dermal exposure.The determination of monoethanolamine has traditionally been difficult and analytical methods available are little adapted for occupational exposure assessments. For monoethanolamine air concentrations, a sampling and analytical method was already available and could be used. However, a method to analyses samples for skin exposure assessments as well as samples of skin permeation experiments was missing. Therefore one main objective of this master thesis was to search an already developed and described analytical method for the measurement of monoethanolamine in water solutions, and to set it up in the laboratory. Monoethanolamine was analyzed after a derivatisation reaction with o-pthtaldialdehyde. The derivated fluorescing monoethanolamine was then separated with high performance liquid chromatography and detection took place with a fluorescent detector. The method was found to be suitable for qualitative and quantitative analysis of monoethanolamine. An exposure assessment was conducted in the cleaning sector to measure the respiratory and dermal exposures to monoethanolamine during floor cleaning. Stationary air samples (n=36) were collected in 8 companies and samples for dermal exposures (n=12) were collected in two companies. Air concentrations (Mean = 0.18 mg/m3, Standard Deviation = 0.23 mg/m3, geometric Mean = 0.09 mg/m3, Geometric Standard Deviation = 3.50) detected were mostly below 1/10 of the Swiss 8h time weighted average occupational exposure limit. Factors that influenced the measured monoethanolamine air concentrations were room size, ventilation system and the concentration of monoethanolamine in the cleaning product and amount of monoethanolamine used. Measured skin exposures ranged from 0.6 to 128.4 mg/sample. Some cleaning workers that participated in the skin exposure assessment did not use gloves and had direct contact with the solutions containing the cleaning product and monoethanolamine. During the entire sampling campaign, cleaning workers mostly did not use gloves. Cleaning workers are at risk to be regularly exposed to low air concentrations of monoethanolamine. This exposure may be problematic if a worker suffers from allergic reactions (e.g. Asthma). In that case a substitution of the cleaning product may be a good prevention measure as several different cleaning products are available for similar cleaning tasks. Currently there are no occupational exposure limits to compare the skin exposures that were found. To prevent skin exposures, adaptations of the cleaning techniques and the use of gloves should be considered. The simultaneous skin and airborne exposures might accelerate adverse health effects. Overall the risks caused by exposures to monoethanolamine are considered as low to moderate when the cleaning products are used correctly. Whenever possible, skin exposures should be avoided. Further research should consider especially the dermal exposure routes, as very high exposures might occur by skin contact with cleaning products. Dermatitis but also sensitization might be caused by skin exposures. In addition, new biomedical insights are needed to better understand the risks of the dermal exposure. Therefore skin permeability experiments should be considered.

Consequences of gestational stress on GABAergic modulation of respiratory activity in developing newborn pups.

The GABAergic system modulates respiratory activity and undergoes substantial changes during early life. Because this maturation process is sensitive to stress, we tested the hypothesis that gestational stress (GS) alters development of GABAergic modulation of respiratory control in rat pups. The respiratory responses to the selective GABAA receptor agonist muscimol were compared between pups born to dams subjected to GS (bright light and predator odor; 20 min/day from G9 to G19) or maintained under standard (control) conditions. Respiratory activity was measured on 1 and 4 days old pups of both sexes using in vivo (whole body plethysmography) and in vitro (isolated brainstem-spinal cord preparation) approaches. In intact pups, muscimol injection (0.75 mg/kg; i.p.) depressed minute ventilation; this response was less in GS pups, and at P4, muscimol augmented minute ventilation in GS females. Bath application of muscimol (0.01-0.5 μM) onto brainstem preparations decreased inspiratory (C4) burst frequency and amplitude in a dose-dependent manner; the responsiveness decreased with age. However, GS had limited effects on these results. We conclude that the results obtained in vivo are consistent with our hypothesis and show that GS delays maturation of GABAergic modulation of respiratory activity. The differences in the results observed between experimental approaches (in vivo versus in vitro) indicate that the effect of prenatal stress on maturation of GABAergic modulation of respiratory control mainly affects the peripheral/metabolic components of the respiratory control system.

Low incidence of severe respiratory syncytial virus infections in lung transplant recipients despite the absence of specific therapy.

BACKGROUND: Respiratory syncytial virus (RSV) infections in lung transplant recipients (LTRs) have been associated with significant morbidity and mortality. Immunoglobulins, ribavirin, and palivizumab are suggested treatments for both pre-emptive and therapeutic purposes. However, in the absence of randomized, placebo-controlled trials, efficacy is controversial and there is toxicity as well as cost concerns. METHODS: We retrospectively reviewed cases of lower respiratory tract RSV infections in adult LTRs. Diagnosis was based on clinical history, combined with a positive polymerase chain reaction (PCR) and/or viral cultures of bronchoalveolar lavage (BAL) specimens. RESULTS: Ten symptomatic patients were identified (7 men and 3 women, age range 28 to 64 years). All were hospitalized for community-acquired respiratory tract infections. Two patients had a concomitant acute Grade A3 graft rejection, and 1 patient had a concomitant bacterial pneumonia. Eight patients did not receive a specific anti-RSV treatment because of clinical stability and/or improvement at the time of RSV diagnosis. Only 2 patients (1 with Grade A3 allograft rejection and 1 requiring mechanical ventilation) received ribavirin and palivizumab. All patients recovered without complications and with no persistent RSV infection. However, bronchiolitis obliterans (BOS) staging worsened in 6 patients during the mean follow-up of 45 months. CONCLUSIONS: Our data suggest that mild RSV infections in LTRs might evolve favorably in the absence of specific anti-viral therapy. However, this observation needs confirmation in a large clinical trial specifically investigating the development of BOS in untreated vs treated patients.

Body composition by X-ray absorptiometry and bioelectrical impedance in chronic respiratory insufficiency patients.

Nutrition assessment is important during chronic respiratory insufficiency to evaluate the level of malnutrition or obesity and should include body composition measurements. The appreciation of fat-free and fat reserves in patients with chronic respiratory insufficiency can aid in designing an adapted nutritional support, e.g., nutritional support in malnutrition and food restriction in obesity. The purpose of the present study was to cross-validate fat-free and fat mass obtained by various bioelectric impedance (BIA) formulas with the fat-free and fat mass measured by dual-energy X-ray absorptiometry (DXA) and determine the formulas that are best suited to predict the fat-free and fat mass for a group of patients with severe chronic respiratory insufficiency. Seventy-five patients (15 women and 60 men) with chronic obstructive and restrictive respiratory insufficiency aged 45-86 y were included in this study. Body composition was calculated according to 13 different BIA formulas for women and 12 for men and compared with DXA. Because of the variability, calculated as 2 standard deviations, of +/- 5.0 kg fat-free mass for women and +/- 6.4 kg for men for the best predictive formula, the use of the various existing BIA formulas was considered not clinically relevant. Therefore disease-specific formulas for patients with chronic respiratory insufficiency should be developed to improve the prediction of fat-free and fat mass by BIA in these patients.

Food allergy: Evaluation of the quality of life in Swiss children

Background: Food allergy in children, an increasingly prevalent disease, significantly affects the quality of life. Its impact can be analyzed by the recently validated French version of the Food Allergy Quality of Life Questionnaire (FAQLQ). Objectives: The aim of our study was to evaluate the quality of life in a small sample of Swiss children with IgE-mediated food allergy. Methods: Information were collected with the questionnaire among 0-12 years old children and their parents during a scheduled allergy visit, and analysed in term of emotional impact, food anxiety and social and food limitations. Patients were divided according to the questionnaire in three age groups: group 1 from 0 to 3 years, group 2 from 4 to 6 years and group 3 from 7 up to 12 years. Results: 30 food allergic patients were included, with a girl/boy ratio of 1:1.14. Median age was 6 years. 56% suffered from or had a history of eczema, 23% of rhino-conjunctivitis, 30% of asthma, and 13% reported a drug allergy. None had insect venom allergy. 57% were known to be allergic to one food, 20% to two foods, 20% to 3 foods and 3% had 3 or more food allergies. Tree nuts (51% of all allergies) as well as eggs (28 %) were the major allergies. Emotional impact had a total score of 1.54 but showed differences between age groups. In group 1 it was lower with 0.23, in group 2 the score was 2.03 and 1.77 in group 3. Food anxiety total score was 1.9; 0.76 in group 1, 2.31 in group 2 and 2.23 in group 3. Social and food limitations showed similar results with a total score of 1.73 and 1.23 in group 1, 2.05 in group 2 and 1.68 for group 3. Conclusion: Food allergy affects the quality of life of Swiss children. Our preliminary results on a small sample are comparable to previously published data. We show that the impact of food allergy on daily life increases when the child starts school and social activities.

Reversible mitochondrial respiratory chain impairment during symptomatic hyperlactatemia associated with antiretroviral therapy

Direct evidence confirming the hypothesis that a dysfunction of the mitochondrial respiratory chain (MRC) underlies the pathogenesis of hyperlactatemia associated with highly active antiretroviral therapy (HAART) is scarce. We studied mitochondrial DNA (mtDNA) content and MRC function in the skeletal muscle of an HIV-infected patient during an episode of symptomatic hyperlactatemia. Skeletal muscle biopsy was performed during the episode when the patient was symptomatic and 3 months later when the patient was clinically recovered. Assessment of mitochondria was performed using histological, polarographic, spectrophotometrical, and Southern blot and real time PCR DNA quantification methods. The histological study disclosed extensive mitochondrial impairment in the form of ragged-red fibers or equivalents on oxidative reactions. These findings were associated with an increase in mitochondrial content and a decrease in both mitochondrial respiratory capacity and MRC enzyme activities. Mitochondrial DNA content declined to 53% of control values. Mitochondrial abnormalities had almost disappeared later when the patient became asymptomatic. Our findings support the hypothesis that MRC dysfunction stands at the basis of HAART-related hyperlactatemia.

Reversible mitochondrial respiratory chain impairment during symptomatic hyperlactatemia associated with antiretroviral therapy

Direct evidence confirming the hypothesis that a dysfunction of the mitochondrial respiratory chain (MRC) underlies the pathogenesis of hyperlactatemia associated with highly active antiretroviral therapy (HAART) is scarce. We studied mitochondrial DNA (mtDNA) content and MRC function in the skeletal muscle of an HIV-infected patient during an episode of symptomatic hyperlactatemia. Skeletal muscle biopsy was performed during the episode when the patient was symptomatic and 3 months later when the patient was clinically recovered. Assessment of mitochondria was performed using histological, polarographic, spectrophotometrical, and Southern blot and real time PCR DNA quantification methods. The histological study disclosed extensive mitochondrial impairment in the form of ragged-red fibers or equivalents on oxidative reactions. These findings were associated with an increase in mitochondrial content and a decrease in both mitochondrial respiratory capacity and MRC enzyme activities. Mitochondrial DNA content declined to 53% of control values. Mitochondrial abnormalities had almost disappeared later when the patient became asymptomatic. Our findings support the hypothesis that MRC dysfunction stands at the basis of HAART-related hyperlactatemia.

Identification of the pathological alterations underlying respiratory failure in myotonic dystrophy transgenic mice

AbstractMyotonic dystrophy type 1 (DM1), also known as Steinert's disease, is an inherited autosomal dominant disease. DM1 is characterized by myotonia, muscular weakness and atrophy, but it has a multisystemic phenotype. The genetic basis of the disease is the abnormal expansion of CTG repeats in the 3' untranslated region of the DM protein kinase (DMPK) gene on chromosome 19. The size of the expansion correlates to the severity of the disease and the age of onset.Respiratory problems have long been recognized to be a major feature of the disease and are the main factor contributing to mortality ; however the mechanisms are only partly known. The aim of our study is to investigate whether respiratory failure results only from the involvement of the dystrophic process at the level of the respiratory muscles or comes also from abnormalities in the neuronal network that generates and controls the respiratory rhythm. The generation of valid transgenic mice displaying the human DM1 phenotype by the group of Dr. Gourdon provided us a useful tool to analyze the brain stem respiratory neurons, spinal phrenic motoneurons and phrenic nerves. We examined therefore these structures in transgenic mice carrying 350-500 CTGs and displaying a mild form of the disease (DM1 mice). The morphological and morphometric analysis of diaphragm muscle sections revealed a denervation of the end-plates (EPs), characterized by a decrease in size and shape complexity of EPs and a reduction in the density of acetylcholine receptors (AChRs). Also a strong and significant reduction in the number of phrenic unmyelinated fibers was detected, but not in the myelinated fibers. In addition, no pathological changes were detected in the cervical motoneurons and medullary respiratory centers (Panaite et al., 2008). These results suggest that the breathing rhythm is probably not affected in mice expressing a mild form of DM1, but rather the transmission of action potentials at the level of diaphragm NMJs is deficient.Because size of the mutation increases over generations, new transgenic mice were obtained from the mice with 350-500 CTGs, resulting from a large increase of CTG repeat in successive generations, these mice carry more than 1300 CTGs (DMSXL) and display a severe DM1 phenotype (Gomes-Pereira et al., 2007). Before we study the mechanism underlying the respiratory failure in DMSXL mice, we analyzed the peripheral nervous system (PNS) in these mice by electrophysiological, histological and morphometric methods. Our results provide strong evidence that DMSXL mice have motor neuropathy (Panaite et al., 2010, submitted). Therefore the DMSXL mice expressing severe DM1 features represent for us a good tool to investigate, in the future, the physiological, structural and molecular alterations underlying respiratory failure in DM1. Understanding the mechanism of respiratory deficiency will help to better target the therapy of these problems in DM1 patients. In addition our results may, in the future, orientate pharmaceutical and clinical research towards possible development of therapy against respiratory deficits associated with the DM1.RésuméLa dystrophic myotonique type 1 (DM1), aussi dénommée maladie de Steinert, est une maladie héréditaire autosomique dominante. Elle est caractérisée par une myotonie, une faiblesse musculaire avec atrophie et se manifeste aussi par un phénotype multisystémique. La base génétique de la maladie est une expansion anormale de répétitions CTG dans une région non traduite en 3' du gène de la DM protéine kinase (DMPK) sur le chromosome 19. La taille de l'expansion est corrélée avec la sévérité et l'âge d'apparition de DM1.Bien que les problèmes respiratoires soient reconnus depuis longtemps comme une complication de la maladie et soient le principal facteur contribuant à la mortalité, les mécanismes en sont partiellement connus. Le but de notre étude est d'examiner si l'insuffisance respiratoire de la DM1 est dû au processus dystrophique au niveau des muscles respiratoires ou si elle est entraînée aussi par des anomalies dans le réseau neuronal qui génère et contrôle le rythme respiratoire. La production par le groupe du Dr. Gourdon de souris transgéniques de DM1, manifestant le phénotype de DM1 humaine, nous a fourni un outil pour analyser les nerfs phréniques, les neurones des centres respiratoires du tronc cérébral et les motoneurones phréniques. Par conséquence, nous avons examiné ces structures chez des souris transgéniques portant 350-500 CTG et affichant une forme légère de la maladie (souris DM1). L'analyse morphologique et morphométrique des sections du diaphragme a révélé une dénervation des plaques motrices et une diminution de la taille et de la complexité de la membrane postsynaptîque, ainsi qu'une réduction de la densité des récepteurs à l'acétylcholine. Nous avons aussi détecté une réduction significative du nombre de fibres nerveuses non myélinisées mais pas des fibres myélinisées. Par ailleurs, aucun changement pathologique n'a été détecté pour les neurones moteurs médullaires cervicaux et centres respiratoires du tronc cérébral (Panaite et al., 2008). Ces résultats suggèrent que le iythme respiratoire n'est probablement pas affecté chez les souris manifestant une forme légère du DM1, mais plutôt que la transmission des potentiels d'action au niveau des plaques motrices du diaphragme est déficiente.Comme la taille du mutation augmente au fil des générations, de nouvelles souris transgéniques ont été générés par le groupe Gourdon; ces souris ont plus de 1300 CTG (DMSXL) et manifestent un phénotype sévère du DM1 (Gomes-Pereira et al., 2007). Avant d'étudier le mécanisme sous-jacent de l'insuffisance respiratoire chez les souris DMSXL, nous avons analysé le système nerveux périphérique chez ces souris par des méthodes électrophysiologiques, histologiques et morphométriques. Nos résultats fournissent des preuves solides que les souris DMSXL manifestent une neuropathie motrice (Panaite et al., 2010, soumis). Par conséquent, les souris DMSXL représentent pour nous un bon outil pour étudier, à l'avenir, les modifications physiologiques, morphologiques et moléculaires qui sous-tendent l'insuffisance respiratoire du DM1. La connaissance du mécanisme de déficience respiratoire en DM1 aidera à mieux cibler le traitement de ces problèmes aux patients. De plus, nos résultats pourront, à l'avenir, orienter la recherche pharmaceutique et clinique vers le développement de thérapie contre le déficit respiratoire associé à DM1.

Respiratory failure in a mouse model of myotonic dystrophy does not correlate with the CTG repeat length.

Myotonic dystrophy (DM1) is a multisystemic disease caused by an expansion of CTG repeats in the region of DMPK, the gene encoding DM protein kinase. The severity of muscle disability in DM1 correlates with the size of CTG expansion. As respiratory failure is one of the main causes of death in DM1, we investigated the correlation between respiratory impairment and size of the (CTG)n repeat in DM1 animal models. Using pressure plethysmography the respiratory function was assessed in control and transgenic mice carrying either 600 (DM600) or >1300 CTG repeats (DMSXL). The statistical analysis of respiratory parameters revealed that both DM1 transgenic mice sub-lines show respiratory impairment compared to control mice. In addition, there is no significant difference in breathing functions between the DM600 and DMSXL mice. In conclusion, these results indicate that respiratory impairment is present in both transgenic mice sub-lines, but the severity of respiratory failure is not related to the size of the (CTG)n expansion.

From pathogen defence to food allergy; The multiple facets of the mucosal immune system

Résumé destiné à un large public Le système immunitaire associé aux muqueuses gastro-intestinales doit être capable de protéger notre organisme contre l'invasion de pathogènes. Parallèlement, il doit identifier en Cant que tels, des composés inoffensifs comme la nourriture ou les milliards de bactéries qui résident dans notre intestin. Le travail présenté ici aborde ces deux aspects essentiels au bon fonctionnement de notre muqueuse intestinale. Dans une première partie, la protéine nommée pièce sécrétoire a été étudiée pour ses propriétés protectrices contre le pathogène viral rotavirus. Le rôle de la pièce sécrétoire est de transporter les anticorps que nous produisons vers la surface des muqueuses. En dehors de cette fonction bien connue, il se peut que cette protéine soit également capable de protéger notre organisme contre certains virus. L'hypothèse de travail était donc que la pièce sécrétoire se lie directement au virus, l'empêchant ainsi d'infecter des cellules épithéliales de l'intestin. En utilisant différentes techniques biochimiques, cette hypothèse s'est révélée fausse car aucune interaction entre la pièce sécrétoire et le virus n'a pu être observée, et logiquement, aucune protection n'a pu prendre place. En revanche, la pièce sécrétoire se lie à d'autres structures pathogéniques et permet ainsi de neutraliser leurs effets néfastes. La pièce sécrétoire participe donc activement à la protection de nos muqueuses, en plus de son rôle de transporteur. La deuxième partie de ce travail avait pour sujet les réactions inappropriées que le système immunitaire induit parfois contre un aliment, ou, autrement dit, les allergies alimentaires. Un modèle d'allergie alimentaire à donc été développé chez la souris et a permis de mesurer plusieurs symptômes et facteurs liés à l'allergie. Puis, ce modèle a été utilisé afin de tester les effets bénéfiques d'une bactérie lactique, dite probiotique, sur le développement de l'allergie. Il a été observé que, sous certaines circonstances, l'administration de la bactérie lactique protégeait entièrement les souris contre les réactions allergiques. L'effet bénéfique dépend donc du probiotique mais également d'autres facteurs encore inconnus â ce jour. Cette étude ouvre la voie sur la compréhension des mécanismes liés aux allergies alimentaires et sur l'impact que peuvent avoir les bactéries probiotiques sur cette maladie. Résumé Le système immunitaire associé aux muqueuses intestinales doit être capable de différencier les antigènes inoffensifs tels que 1a nourriture ou les bactéries commensales des microorganismes potentiellement dangereux. Cet aspect est essentiel pour le maintien de l'homéostase intestinale et fait l'objet du travail présenté ici. Dans un premier projet, les propriétés protectrices de la protéine appelée pièce sécrétoire (SC) ont été étudiées. SC est une protéine connue pour le transport des immunoglobulines à la surface des muqueuses. Cette protéine est fortement glycosylée paz des sucres complexes, ce qui nous a mené à postuler que SC puisse interagir avec le pathogène rotavirus. Cette hypothèse était soutenue par le fait que ce virus adhère aux cellules épithéliales par des résidus glycosylés. Des analyses biochimiques et biologiques ont démontré qu'aucune interaction entre SC et le virus ne prenait place, et que par conséquent SC n'offrait aucune protection contre ce pathogène. En revanche, SC interagit avec d'autres structures pathogéniques, comme la toxine A de Clostridium difficile, et la molécule d'adhésion intimine de la bactérie entéropathogène Escherichia coli. La liaison se fait par l'intermédiaire des sucres et confère ainsi une protection contre ces pathogènes. Ainsi, SC a été identifié comme agent neutralisant au niveau de l'intestin. La deuxième partie de ce travail abordait le sujet des allergies alimentaires, et avait pour but de tester les effets bénéfiques potentiels d'une bactérie probiotique, Lactobacillus paracasei NCC2461, contre les réactions allergiques. Un modèle marin d'allergie alimentaire a été mis au point, permettant de mesurer des immunoglobulines E, des symptômes allergiques, et la dégranulation de mastocytes. Lorsque le probiotique a été administré aux souris, celles-ci ont été complètement protégées des réactions allergiques dans une première expérience. Cependant, cette protection n'a pas été reproduite et suggère que des facteurs environnementaux encore inconnus sont critiques pour que le probiotique agisse positivement. Ce travail a permis de mettre en évidence la complexité de l'approche des traitements liés aux probiotiques et ouvre la voie sur la compréhension des mécanismes liés à l'allergie. Abstract The mucosal immune system associated to the gastrointestinal mucosa must efficiently distinguish between innocuous antigens, such as food proteins and commensal bacteria and potentially infectious agents. The work presented here deals with these two essential aspects guaranteeing intestinal homeostasis. In the first part of this work, the protective properties of secretory component (SC) toward the pathogen rotavirus were investigated. SC, which allows the transport of polymeric immunoglobulins (Ig) to mucosal surfaces, is highly glycosylated with complex glycan structures. The abundance and the nature of these carbohydrates led us to speculate that SC might interact with rotavirus, which is known to bind target cells with glycan receptors. Using various biological and biochemical techniques, we demonstrated that SC did not interact with rotaviruses, nor protected epithelial cells from infection. However, SC was shown to bind to Clostridium difficile toxin A and to the enteropathogenic Echerischia coli adhesion molecule intimin in a glycan-dependent fashion. These interactions allow in vitro protection of epithelial cells using physiological concentrations of SC. These data identify SC as a microbial scavenger at mucosal surfaces, and in the context of secretory IgA, further enhance the neutralising properties of the complex. The second project was inscribed in the domain of food allergy and aimed to test the modulatory functions of a probiotic strain of Lactobacillus paracasei toward allergic reactions. A model of food-mediated allergy was developed in the mouse using mucosal sensitisation. Several parameters associated to allergy were quantified after allergen challenge, and included allergen-specific IgE, allergic signs like diarrhea and temperature drop, and degranulation of mast cells. Administration of the probiotic strain was shown to completely protect mice from allergic reactions. However, these data were not reproduced, suggesting that unknown environmental factors are required so that protection mediated by the probiotic strain occurs. This study paves the way to the understanding of the mechanisms associated to allergy, and highlights the tremendous complexity that probiotic treatments will have to face.

Two distinct plant respiratory physiotypes might exist which correspond to fast-growing and slow-growing species

The origin of the carbon atoms in CO2 respired by leaves in the dark of several plant species has been studied using 13C/12C stable isotopes. This study was conducted using an open gas exchange system for isotope labeling that was coupled to an elemental analyser and further linked to an isotope ratio mass spectrometer (EA-IRMS) or coupled to a gas chromatography-combustion-isotope ratio mass spectrometer (GC-C-IRMS). We demonstrate here that the carbon, which is recently assimilated during photosynthesis, accounts for nearly ca. 50% of the carbon in the CO2 lost through dark respiration after illumination in fast-growing and cultivated plants and trees and, accounts for only ca. 10% in slow-growing plants. Moreover, our study shows that fast- growing plants, which had the largest percentages of newly fixed carbon of leaf-respired CO2 , were also those with the largest shoot/root ratios, whereas slow-growing plants showed the lowest shoot/root values.

Mutations in NDUFB11, Encoding a Complex I Component of the Mitochondrial Respiratory Chain, Cause Microphthalmia with Linear Skin Defects Syndrome.

Microphthalmia with linear skin defects (MLS) syndrome is an X-linked male-lethal disorder also known as MIDAS (microphthalmia, dermal aplasia, and sclerocornea). Additional clinical features include neurological and cardiac abnormalities. MLS syndrome is genetically heterogeneous given that heterozygous mutations in HCCS or COX7B have been identified in MLS-affected females. Both genes encode proteins involved in the structure and function of complexes III and IV, which form the terminal segment of the mitochondrial respiratory chain (MRC). However, not all individuals with MLS syndrome carry a mutation in either HCCS or COX7B. The majority of MLS-affected females have severe skewing of X chromosome inactivation, suggesting that mutations in HCCS, COX7B, and other as-yet-unidentified X-linked gene(s) cause selective loss of cells in which the mutated X chromosome is active. By applying whole-exome sequencing and filtering for X-chromosomal variants, we identified a de novo nonsense mutation in NDUFB11 (Xp11.23) in one female individual and a heterozygous 1-bp deletion in a second individual, her asymptomatic mother, and an affected aborted fetus of the subject's mother. NDUFB11 encodes one of 30 poorly characterized supernumerary subunits of NADH:ubiquinone oxidoreductase, known as complex I (cI), the first and largest enzyme of the MRC. By shRNA-mediated NDUFB11 knockdown in HeLa cells, we demonstrate that NDUFB11 is essential for cI assembly and activity as well as cell growth and survival. These results demonstrate that X-linked genetic defects leading to the complete inactivation of complex I, III, or IV underlie MLS syndrome. Our data reveal an unexpected role of cI dysfunction in a developmental phenotype, further underscoring the existence of a group of mitochondrial diseases associated with neurocutaneous manifestations.

A bovine model of a respiratory Parachlamydia acanthamoebae infection.

The aim of this study was to evaluate the pathogenicity of Parachlamydia (P.) acanthamoebae as a potential agent of lower respiratory tract disease in a bovine model of induced lung infection. Intrabronchial inoculation with P. acanthamoebae was performed in healthy calves aged 2-3 months using two challenge doses: 10(8) and 10(10) bacteria per animal. Controls received 10(8) heat-inactivated bacteria. Challenge with 10(8) viable Parachlamydia resulted in a mild degree of general indisposition, whereas 10(10) bacteria induced a more severe respiratory illness becoming apparent 1-2 days post inoculation (dpi), affecting 9/9 (100%) animals and lasting for 6 days. The extent of macroscopic pulmonary lesions was as high as 6.6 (6.0)% [median (range)] of lung tissue at 2-4 dpi and correlated with parachlamydial genomic copy numbers detected by PCR, and with bacterial load estimated by immunohistochemistry in lung tissue. Clinical outcome, acute phase reactants, pathological findings and bacterial load exhibited an initial dose-dependent effect on severity. Animals fully recovered from clinical signs of respiratory disease within 5 days. The bovine lung was shown to be moderately susceptible to P. acanthamoebae, exhibiting a transient pneumonic inflammation after intrabronchial challenge. Further studies are warranted to determine the precise pathophysiologic pathways of host-pathogen interaction.

Reduction of respiratory motion artifacts for free-breathing whole-heart coronary MRA by weighted iterative reconstruction.

PURPOSE: To combine weighted iterative reconstruction with self-navigated free-breathing coronary magnetic resonance angiography for retrospective reduction of respiratory motion artifacts. METHODS: One-dimensional self-navigation was improved for robust respiratory motion detection and the consistency of the acquired data was estimated on the detected motion. Based on the data consistency, the data fidelity term of iterative reconstruction was weighted to reduce the effects of respiratory motion. In vivo experiments were performed in 14 healthy volunteers and the resulting image quality of the proposed method was compared to a navigator-gated reference in terms of acquisition time, vessel length, and sharpness. RESULT: Although the sampling pattern of the proposed method contained 60% more samples with respect to the reference, the scan efficiency was improved from 39.5 ± 10.1% to 55.1 ± 9.1%. The improved self-navigation showed a high correlation to the standard navigator signal and the described weighting efficiently reduced respiratory motion artifacts. Overall, the average image quality of the proposed method was comparable to the navigator-gated reference. CONCLUSION: Self-navigated coronary magnetic resonance angiography was successfully combined with weighted iterative reconstruction to reduce the total acquisition time and efficiently suppress respiratory motion artifacts. The simplicity of the experimental setup and the promising image quality are encouraging toward future clinical evaluation. Magn Reson Med 73:1885-1895, 2015. © 2014 Wiley Periodicals, Inc.