Spatial multi-criteria decision analysis for the selection of sentinel regions in tick-borne disease surveillance

BACKGROUND

The implementation of cost-effective surveillance systems is essential for tracking the emerging risk of tick-borne diseases. In Canada, where Lyme disease is a growing public health concern, a national sentinel surveillance network was designed to follow the epidemiological portrait of this tick-borne disease across the country. The surveillance network consists of sentinel regions, with active drag sampling carried out annually in all regions to assess the density of Ixodes spp. ticks and prevalence of various tick-borne pathogens in the tick population. The aim of the present study was to prioritize sentinel regions by integrating different spatial criteria relevant to the surveillance goals.

METHODS

We used spatially-explicit multi-criteria decision analyses (MCDA) to map priority areas for surveillance across Canada, and to evaluate different scenarios using sensitivity analyses. Results were shared with stakeholders to support their decision making for the selection of priority areas to survey during active surveillance activities.

RESULTS

Weights attributed to criteria by decision-makers were overall consistent. Sensitivity analyses showed that the population criterion had the most impact on rankings. Thirty-seven sentinel regions were identified across Canada using this systematic and transparent approach.

CONCLUSION

This novel application of spatial MCDA to surveillance network design favors inclusivity of nationwide partners. We propose that such an approach can support the standardized planning of spatial design of sentinel surveillance not only for vector-borne disease BDs, but more broadly for infectious disease surveillance where spatial design is an important component.

The added value of One Health surveillance: data from questing ticks can provide an early signal for anaplasmosis outbreaks in animals and humans

OBJECTIVE

In 2021, a first outbreak of anaplasmosis occurred in animals and humans in southern Québec, with 64% of confirmed human cases located in Bromont municipality. Ixodes scapularis ticks and Peromyscus mouse ear biopsies collected in Bromont from 2019 to 2021 were analyzed for Anaplasma phagocytophilum (Ap) with the objective of determining whether an early environmental signal could have been detected before the outbreak.

METHODS

Samples were collected for a concurrent study aiming to reduce Lyme disease risk. Between 2019 and 2021, up to 14 experimental sites were sampled for ticks and capture of small mammals took place on three sites in 2021. Samples were screened for Ap using multiplex real-time PCR, and genetic strains were identified using a single-nucleotide polymorphism assay.

RESULTS

Analyses showed an increase of 5.7% in Ap prevalence in ticks (CI95: 1.5-9.9) between 2019 and 2020, i.e., one year before the outbreak. A majority of Ap-positive ticks were infected with the zoonotic strain (68.8%; CI95: 50.0-83.9) during the study period. In 2021, 2 of 59 captured Peromycus mice were positive for Ap, for a prevalence of 3.4% (CI95: 0.4-11.7).

CONCLUSION

We conclude that data collected in Bromont could have provided an early signal for an anaplasmosis risk increasing in the targeted region. This is a reminder that integrated surveillance of tick-borne diseases through structured One Health programs, i.e. systematically integrating data from humans, animals and the environment, can provide useful and timely information for better preparedness and response in public health.

Clinical practice guidelines: management of severe bronchiolitis in infants under 12 months old admitted to a pediatric critical care unit

PURPOSE

We present guidelines for the management of infants under 12 months of age with severe bronchiolitis with the aim of creating a series of pragmatic recommendations for a patient subgroup that is poorly individualized in national and international guidelines.

METHODS

Twenty-five French-speaking experts, all members of the Groupe Francophone de Réanimation et Urgence Pédiatriques (French-speaking group of paediatric intensive and emergency care; GFRUP) (Algeria, Belgium, Canada, France, Switzerland), collaborated from 2021 to 2022 through teleconferences and face-to-face meetings. The guidelines cover five areas: (1) criteria for admission to a pediatric critical care unit, (2) environment and monitoring, (3) feeding and hydration, (4) ventilatory support and (5) adjuvant therapies. The questions were written in the Patient-Intervention-Comparison-Outcome (PICO) format. An extensive Anglophone and Francophone literature search indexed in the MEDLINE database via PubMed, Web of Science, Cochrane and Embase was performed using pre-established keywords. The texts were analyzed and classified according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. When this method did not apply, an expert opinion was given. Each of these recommendations was voted on by all the experts according to the Delphi methodology.

RESULTS

This group proposes 40 recommendations. The GRADE methodology could be applied for 17 of them (3 strong, 14 conditional) and an expert opinion was given for the remaining 23. All received strong approval during the first round of voting.

CONCLUSION

These guidelines cover the different aspects in the management of severe bronchiolitis in infants admitted to pediatric critical care units. Compared to the different ways to manage patients with severe bronchiolitis described in the literature, our original work proposes an overall less invasive approach in terms of monitoring and treatment.

Criteria for selecting sentinel unit locations in a surveillance system for vector-borne disease: A decision tool

Objectives

With vector-borne diseases emerging across the globe, precipitated by climate change and other anthropogenic changes, it is critical for public health authorities to have well-designed surveillance strategies in place. Sentinel surveillance has been proposed as a cost-effective approach to surveillance in this context. However, spatial design of sentinel surveillance system has important impacts on surveillance outcomes, and careful selection of sentinel unit locations is therefore an essential component of planning.

Methods

A review of the available literature, based on the realist approach, was used to identify key decision issues for sentinel surveillance planning. Outcomes of the review were used to develop a decision tool, which was subsequently validated by experts in the field.

Results

The resulting decision tool provides a list of criteria which can be used to select sentinel unit locations. We illustrate its application using the case example of designing a national sentinel surveillance system for Lyme disease in Canada.

Conclusions

The decision tool provides researchers and public health authorities with a systematic, evidence-based approach for planning the spatial design of sentinel surveillance systems, taking into account the aims of the surveillance system and disease and/or context-specific considerations.

L’infection a SARS-CoV-2 pourrait-elle induire des rhumatismes inflammatoires chroniques ? Une enquête nationale française

Introduction

Les cas publiés de manifestations inflammatoires non microcristallines après COVID-19 sont exceptionnels. L’objectif de cette étude est de décrire les caractéristiques clinicobiologiques, morphologiques et de suivi des manifestations rhumatologiques observées suite à une infection récente à SARS-CoV-2.

Matériels et méthodes

Cette étude est une série française ambispective, multicentrique, de patients présentant une infection à SARS-CoV-2, associée à la survenue de manifestations rhumatologiques. Elle provient des premiers résultats d’un registre national (étude du CRI) de patients atteints du SARS-CoV-2. Du 7 avril 2020 au 24 juin 2021, nous avons recueilli les données clinicobiologiques, morphologiques, et la prise en charge de ces manifestations.

Résultats

Cette étude comprend 15 patients ayant présenté une infection à SARS-CoV-2 avec haute suspicion clinique et cas contact confirmé (n = 2), confirmée par PCR nasale (n = 8), trachéale (n = 2), test salivaire (n = 1) ou sérologie (n = 2). L’âge moyen est de 55,1 ans (19–72) ; 53,3 % des patients sont de sexe féminin. Les comorbidités principales sont une hypertension artérielle (40 %), un diabète de type 2 (20 %), une obésité (20 %). Aucun patient ne présente d’antécédent de rhumatisme inflammatoire chronique sous traitement de fond, maladie auto-immune ou déficit immunitaire. Deux patients présentent un antécédent de psoriasis dans l’enfance. Le délai moyen d’apparition des manifestations rhumatologiques est de 32,9 jours après les premiers symptômes d’infection à SARS-CoV-2 et de 23,9 jours après confirmation diagnostique : arthralgies (100 %), myalgies (47 %), au moins une synovite (86 %). L’atteinte est majoritairement bilatérale (67 %), asymétrique (54 %), poly- ou oligo-articulaire (73 %). Trois patients présentent des signes extra-articulaires évoquant une maladie inflammatoire systémique (syndrome néphrotique, engelures, syndrome de Raynaud, papules de Gottron, télangiectasies). Un syndrome inflammatoire biologique est présent chez 80 % des patients. Un patient présente une positivité du facteur rhumatoïde à taux significatif, alors que les anticorps anti-CCP ne sont présents chez aucun d’entre eux. Les anticorps antinucléaires sont positifs à taux significatif (seuil de 1/160) chez 20 % des patients. Les radiographies ne montrent pas d’atteinte structurale. Dix patients ont bénéficié d’une évaluation échographique : sept présentent au moins une synovite, dont quatre avec hyperhémie Doppler. Une seule ponction articulaire de genou a été réalisée, retrouvant un liquide inflammatoire à prédominance de polynucléaires neutrophiles, sans cristaux. Nous disposons de données de suivi pour 12 patients. Le délai de suivi moyen par rapport au j0 des symptômes de l’infection à SARS-CoV-2 est de 15 mois (8–18). L’évolution a été favorable sous AINS ou corticothérapie chez 6 patients, et après abstention thérapeutique chez 2 patients. Parmi les 12 patients suivis, 6 ont présenté une rechute articulaire. Quatre patients ont fait l’objet d’un traitement de fond : csDMARDS (méthotrexate n = 1, sulfasalazine n = 1), bDMARDS (infliximab n = 1, adalimumab n = 1).

Conclusion

Notre étude rapporte plusieurs cas de manifestations rhumatologiques inflammatoires, non érosives, après une infection à SARS-CoV-2, après un suivi moyen de 15 mois. Elles restent exceptionnelles. L’hypothèse d’une arthrite de type réactionnelle ne peut être écartée.

Modelling Spatiotemporal Patterns of Lyme Disease Emergence in Québec

Lyme disease is a growing public health problem in Québec. Its emergence over the last decade is caused by environmental and anthropological factors that favour the survival of Ixodes scapularis, the vector of Lyme disease transmission. The objective of this study was to estimate the speed and direction of human Lyme disease emergence in Québec and to identify spatiotemporal risk patterns. A surface trend analysis was conducted to estimate the speed and direction of its emergence based upon the first detected case of Lyme disease in each municipality in Québec since 2004. A cluster analysis was also conducted to identify at-risk regions across space and time. These analyses were reproduced for the date of disease onset and date of notification for each case of Lyme disease. It was estimated that Lyme disease is spreading northward in Québec at a speed varying between 18 and 32 km/year according to the date of notification and the date of disease onset, respectively. A significantly high risk of disease was found in seven clusters identified in the south-west of Québec in the sociosanitary regions of Montérégie and Estrie. The results obtained in this study improve our understanding of the spatiotemporal patterns of Lyme disease in Québec, which can be used for proactive, targeted interventions by public and clinical health authorities.

A Portrait of Sentinel Surveillance Networks for Vector-Borne Diseases: A Scoping Review Supporting Sentinel Network Design

Vector-borne diseases (VBDs) are continuing to emerge globally, requiring new surveillance systems to follow increasing VBD risk for human populations. Sentinel surveillance is an approach that allows tracking of disease risk through time using limited resources. However, there is no consensus on how best to design a sentinel surveillance network in the context of VBDs. We conducted a scoping review to compare VBD sentinel surveillance systems worldwide with the aim of identifying key design features associated with effective networks. Overall, VBD surveillance networks were used most commonly for malaria, West Nile virus, and lymphatic filariasis. A total of 45 criteria for the selection of sentinel unit location were identified. Risk-based criteria were the most often used, and logistic regression showed that using risk-based criteria dependent on host animals is particularly correlated with surveillance system sensitivity (p < 0.018). We identify tools that could prove valuable for sentinel surveillance network design, including a standardized approach for evaluating surveillance systems and a tool to prioritize criteria for selecting optimal geographic locations for spatial sentinel units.

Are Nutritional Guidelines Followed in the Pediatric Intensive Care Unit?

Background: French (2014) and American (2017) pediatric guidelines recommend starting enteral nutrition (EN) early in pediatric intensive care. The aims of this study were to compare the applicability of the guidelines in the pediatric intensive care unit (PICU) and to identify risk factors of non-application of the guidelines. Methods: This retrospective, single-center study was conducted in a medical-surgical PICU between 2014 and 2016. All patients from 1 month to 18 years old with a length of stay >48 h and an exclusive EN at least 1 day during the PICU stay were included. The outcome variable was application of the 2014 and 2017 guidelines, defined by energy intakes ≥90% of the recommended intake at least 1 day as defined by both guidelines. The risk factors of non-application were studied comparing "optimal EN" vs. "non-optimal EN" groups for both guidelines. Results: In total, 416 children were included (mortality rate, 8%). Malnutrition occurred in 36% of cases. The mean energy intake was 34 ± 30.3 kcal kg^-1 day^-1. The 2014 and 2017 guidelines were applied in 183 (44%) and 296 (71%) patients, respectively (p < 0.05). Following the 2017 guidelines, enteral energy intakes were considered as "satisfactory enteral intake" for 335 patients (81%). Hemodynamic failure was a risk factor of the non-application of both guidelines. Conclusion: In our PICU, the received energy intake approached the level of intake recommended by the American 2017 guidelines, which used the predictive Schofield equations and seem more useful and applicable than the higher recommendations of the 2014 guidelines. Multicenter studies to validate the pediatric guidelines seem necessary.

Practical implementation of automated closed-loop insulin delivery: A French position statement

Automated closed-loop (CL) insulin therapy has come of age. This major technological advance is expected to significantly improve the quality of care for adults, adolescents and children with type 1 diabetes. To improve access to this innovation for both patients and healthcare professionals (HCPs), and to promote adherence to its requirements in terms of safety, regulations, ethics and practice, the French Diabetes Society (SFD) brought together a French Working Group of experts to discuss the current practical consensus. The result is the present statement describing the indications for CL therapy with emphasis on the idea that treatment expectations must be clearly defined in advance. Specifications for expert care centres in charge of initiating the treatment were also proposed. Great importance was also attached to the crucial place of high-quality training for patients and healthcare professionals. Long-term follow-up should collect not only metabolic and clinical results, but also indicators related to psychosocial and human factors. Overall, this national consensus statement aims to promote the introduction of marketed CL devices into standard clinical practice.

Enhance quality care performance: Determination of the variables for establishing a common database in French paediatric critical care units

Selected variables for the French Paediatric Intensive Care registry.

RATIONALE, AIMS, AND OBJECTIVES

Providing quality care requires follow-up in regard to clinical and economic activities. Over the past decade, medical databases and patient registries have expanded considerably, particularly in paediatric critical care medicine (eg, the Paediatric Intensive Care Audit Network (PICANet) in the UK, the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry in Australia and New Zealand, and the Virtual Paediatric Intensive Care Unit Performance System (VPS) in the USA). Such a registry is not yet available in France. The aim of this study was to determine variables that ought to be included in a French paediatric critical care registry.

METHODS

Variables, items, and subitems from 3 foreign registries and 2 French local databases were used. Items described each variable, and subitems described items. The Delphi method was used to evaluate and rate 65 variables, 90 items, and 17 subitems taking into account importance or relevance based on input from 28 French physicians affiliated with the French Paediatric Critical Care Group. Two ratings were used between January and May 2013.

RESULTS

Fifteen files from 10 paediatric intensive care units were included. Out of 65 potential variables, 48 (74%) were considered to be indispensable, 16 (25%) were considered to be optional, and 1 (2%) was considered to be irrelevant. Out of 90 potential items, 62 (69%) were considered to be relevant, 23 (26%) were considered to be of little relevance, and 5 (6%) were considered to be irrelevant. Out of 17 potential subitems, 9 (53%) were considered to be relevant, 6 (35%) were considered to be of little relevance, and 2 (12%) were considered to be irrelevant.

CONCLUSIONS

The necessary variables that ought to be included in a French paediatric critical care registry were identified. The challenge now is to develop the French registry for paediatric intensive care units.

Monitoring Cerebral and Renal Oxygenation Status during Neonatal Digestive Surgeries Using Near Infrared Spectroscopy

BACKGROUND

Depending on the initial pathology, hypovolemia, intra-abdominal hypertension, and sepsis are often encountered in neonatal digestive surgery. Accurate newborn monitoring during and after surgery is essential to adapt resuscitation protocols. Near infrared spectroscopy (NIRS) is non-invasive and can detect hypoperfusion which indicates a low circulatory blood flow, regardless of the cause.

OBJECTIVE

Evaluating changes in cerebral and renal regional oxygen saturation during neonatal digestive surgeries, conducted according to normal practices, with commonly used monitoring parameters. Analyzing retrospectively the inter-relationships between NIRS values and mean arterial pressure (MAP) values as well as pre-ductal SpO₂.

METHODS

Prospective, descriptive, monocentric study. All neonates referred for surgery were included. NIRS allows the measurement of cerebral and renal oxygenation fluctuations, as well as calculating difference in intraoperative and postoperative values.

RESULTS

Nineteen patients were included. Cerebral regional oxygen saturation (C rSO₂) values were stable while renal regional oxygen saturation (R rSO₂) values tended to decrease with time during surgery. Indeed, 72% of rSO₂ decline episodes occurred after the first 30 min of surgery, without any significant statistical differences for the next 90 min of surgery. After surgery, the lowest average C and R rSO₂ values were evidenced during the first 6 h, with 60% of C rSO₂ and R rSO₂ anomalies occurring in that time frame. There was no significant statistical difference observed in the following 18 h. There was a significant correlation between R rSO₂ and SpO₂ values (p < 0.01), but not with C rSO₂ values. There was no correlation with the MAP either for the C rSO₂ values or R rSO₂ ones.

CONCLUSION

NIRS is a promising non-invasive bedside tool to monitor cerebral and tissue perfusion, analyzing tissue microcirculation. NIRS has its interest to guide neonatal digestive surgeries (bowel manipulation, viscera reduction) and may represent an early warning for identifying patients requiring resuscitation during or after these surgeries.

Implementation of an in-house quantitative real-time polymerase chain reaction method for Hepatitis B virus quantification in West African countries

Hepatitis B virus (HBV) is a major cause of chronic liver disease worldwide. HBV infection is diagnosed by serological tests, while real-time polymerase chain reaction (qRT-PCR) assays are used to quantify viral load, which is a crucial parameter to determine viral replication and to monitor antiviral treatments. However, measuring viral load in resource-limited countries remains nonsystematic, due to the high cost of commercial kits. Here, we describe the development, validation and implementation of a low-cost, in-house qRT-PCR assay to monitor HBV viral load in chronic carriers enrolled in the PROLIFICA programme in the Gambia and Senegal. Over 1500 HBsAg-positive patients, including 210 chronically infected HBV patients, who were given antiviral treatment (tenofovir), were monitored by qRT-PCR using the SYBR Green- and HBV-specific primers. Twenty-four tenofovir-treated patients were followed up and their viral load was tested every 3 months over the 12-month experimental time course. Compared to commercial assays, our in-house assay was shown to be (i) highly reliable, with good intra- and interassay reproducibility over a wide range (45-4.5 × 108 copies mL-1 ), (ii) very similar in the viral loads detected (R2  = .90), (iii) highly sensitive, as it detected loads as low as 30 copies mL-1 (~5 IU mL-1 ), (iv) cheaper (2- to 3-fold), (v) easier to implement and (vi) more rapid. Based on our experience, we recommend this assay as a reliable alternative to commercial assays, for monitoring HBV viraemia in resource-limited, highly endemic countries to reduce the cost and technical obstacles associated with commercial kits.

Factors controlling BTEX and chlorinated solvents plume length under natural attenuation conditions

Natural attenuation is presently used at numerous sites where groundwater is contaminated. In order to simulate this attenuation, reactive transport models are often used but they are quite complex and depend on both physical and chemical conditions in the aquifer. As complex numerical models cannot be used to study all possible cases, we develop here analytical solutions to draw general conclusions. Our strategy, called MIKSS (Mixed Instantaneous and Kinetics Superposition Sequence), allows the calculation of the concentrations of all reacting substances in a plume. It is an extension of the superimposition principle that is able to treat the case of joint kinetics and instantaneous reactions. The basic equations have been extended to treat different reactions that occur in the plume core and at its fringe. At first we consider one organic substance degraded under all oxidising conditions (toluene for instance). For this problem the size of the plume depends on the reduced source width and on the ratio of the organic substance concentration to the sum of the electron acceptors' concentrations. For several BTEX substances having different degradation behaviour the formulation is similar, but leads to quite different plume lengths for each substance. Contrary to the case of one substance, the plumes can be quite long and may not satisfy the target risk level. For chlorinated solvents we developed a specific approach to take under consideration all reactions and particularly the competition for hydrogen. A formula is given to assess the size of the plume core, i.e. the zone with highly reducing conditions. The factors influencing the core length are the same as for BTEX (source width, dispersivity, organic carbon content). The size of the TCE plume is calculated from the plume core length and the kinetic constant of TCE degradation. Using assumptions of degradation constants for DCE and VC it is also possible to calculate the longitudinal concentration profile of these substances. The degradation of moderately substituted solvents under oxic conditions reduces the size of their plumes but under these conditions TCE becomes the major threat. Among the conditions studied in this paper, very few chlorinated solvents sites can lead to a negligible risk at an acceptable distance from the source.

Same efficacies of ipratropium and salbutamol in reversing methacholine-induced bronchoconstriction

Efficacy of salbutamol (S) was compared to that of ipratropium (I) or to their association, after methacholine challenge testing (MCT). MCT was performed in 4 groups of 10 patients suspected to suffer from asthma; mean changes in FEV1, maximal midexpiratory flow rate (MMFR), and airway resistance (Raw) were the same in all groups. After MCT, the group 1 patients inhaled S and then I, 10 min later; both drugs were given in the reverse order to the group 2 patients. The group 3 patients inhaled a mixture of both drugs just after MCT; the group 4 patients were not given any bronchodilator till the 20th min after MCT, when they inhaled S. Short-term (10 min) bronchodilator effects of S, I or S + I on spirometric variables were of the same magnitude and Raw returned to its baseline value. Further improvement (10-20 min) in FEV1 was mainly due to spontaneous recovery, whereas further increase in MMFR was due also to bronchodilator actions of drugs. It is concluded that ipratropium could be proposed as an alternative bronchodilator to salbutamol after MCT.

T-cell activation in occupational asthma and rhinitis

BACKGROUND

Allergic asthma and rhinitis are described as associated with a Th2 activation. However, recent works indicate that a Th1 activation can also be associated with these diseases, concomitantly to a defect in regulatory T (Treg) cell activation. Occupational asthma (OA) and occupational rhinitis (OR) are peculiar cases of these diseases in which the T-cell activation profile is largely unknown.

OBJECTIVE

To characterize T-cell activation induced after a specific inhalation test (SIT) in OA and OR.

MATERIAL AND METHODS

A total of 21 subjects with OA, 10 subjects with OR, 10 exposed nonallergic (ENA) subjects, and 14 healthy volunteers were included. The SIT with the incriminated substance was performed in patients and ENA subjects. Blood and induced sputum were obtained before and after SIT. T cells were analysed for CD69, CD25, IL-13, and IFN-gamma expression by flow cytometry. IL-4 and IFN-gamma were assayed by enzyme-linked immunosorbent assay (ELISA) in cell culture supernatants. Treg cells were identified as CD4(+)CD25(+high)CD45RO(+)CD69(-) T cells in peripheral blood.

RESULTS

Baseline IFN-gamma production was decreased in OA and OR compared with controls. The SIT induced an increase in both Th1 and Th2 cells in blood and sputum from OA. In this group, the proportion of peripheral Treg cells decreased after SIT. Similar results were found in the CD8(+) population. ELISA assays were concordant with flow cytometry. In OR, an attenuated activation profile was found, with an increase in the proportion of IL-13-producing T cells after SIT. By contrast, in ENA subjects, SIT induced Th2 activation, with an increase in Treg cells and a decrease in Th1 cells.

CONCLUSIONS

Our results demonstrate a gradient of T-cell activation from a tolerating profile in ENA subjects to an inflammatory profile in OA, with an intermediate stage in OR.

Scaling exponents for fracture surfaces in homogeneous glass and glassy ceramics

We investigate the scaling properties of postmortem fracture surfaces in silica glass and glassy ceramics. In both cases, the 2D height-height correlation function is found to obey Family-Viseck scaling properties, but with two sets of critical exponents, in particular, a roughness exponent zeta approximately 0.75 in homogeneous glass and zeta approximately 0.4 in glassy ceramics. The ranges of length scales over which these two scalings are observed are shown to be below and above the size of the process zone, respectively. A model derived from linear elastic fracture mechanics in the quasistatic approximation succeeds to reproduce the scaling exponents observed in glassy ceramics. The critical exponents observed in homogeneous glass are conjectured to reflect the damage screening occurring for length scales below the size of the process zone.

Increased diaphragmatic strength and tolerance to fatigue after bilateral lung transplantation: an electromyographic study

We evaluated the diaphragmatic function of seven patients with severe chronic respiratory failure before and after a bilateral lung transplantation (BLT), with follow-up at one year of pulmonary function tests, maximal inspiratory mouth pressure (MIP) and surface diaphragmatic electromyogram (Edi). The patients were asked to sustain target inspiratory pressures at -15, -30, and -50 cmH(2)O. We measured the endurance time (Tlim) to sustain inspiratory efforts and the power spectrum density function of Edi at each inspiratory maneuver. The Edi power spectra was analysed in terms of median frequency (MF), total power (TP) and energies in high-and low-frequency bands (EL and EH). Before BLT, a defect of the diaphragmatic function was evident: MIP was 62+/-7% of the predicted value and the Tlim measured at each inspiratory effort was very short ( 13+/-1 s, 10+/-1 s and 8+/-1 s at pressures of -15, -30, and -50 cmH(2)O, respectively). One month after BLT, the Tlim began to increase at all target inspiratory pressures and at 6 months MIP recovered to normal values. One month after BLT, there was a significant decrease in TP measured at the beginning of each inspiratory efforts and also an increase in the concomitant MF value. BLT markedly accentuated the maximal variations of TP, MF and low-frequency Edi energy. Some hypotheses are raised to explain this dramatic improvement in diaphragmatic function after BLT.

Assessment of T lymphocyte cytokine production in induced sputum from asthmatics: a flow cytometry study

BACKGROUND

Asthma results from a bronchial inflammation in which Th2 lymphocytes play a pivotal role, as shown in invasive bronchial biopsies and broncho-alveolar lavages. Induced sputum (IS) is a non-invasive method of recovery of bronchial cells, which can be repeated in the same patients. However, lymphocyte activation has not been studied in IS to date, because of the low number of T cells recovered. Herein we took advantage of flow cytometry, a method suitable for the study of small cell populations, to assess T cell cytokine production in IS.

OBJECTIVES

(1) To assess induced sputum T cell cytokine production by flow cytometry in asthmatic subjects and controls. (2) To compare the T cell cytokine production between symptomatic and non-symptomatic asthmatics.

METHODS

Thirteen asthmatics and 19 controls were included. Sputum was induced by a hypertonic saline. Sputum cells were stimulated and intracellular IL-13 and IFN-gamma were detected in T cells by flow cytometry.

RESULTS

Stimulation induced an increase of IL-13 and IFN-gamma production by T cells. This increase was higher in asthmatics. IL-13-producing T cells were increased in asthmatics after stimulation. In symptomatic asthma, IFN-gamma-producing T cells were in higher proportion than in controlled asthma.

CONCLUSION

IS T cell cytokine production indicates a basic Th2 bias in asthma, accompanied during symptoms by a Th1-like activation. These results open the field for longitudinal studies of the variation of T cell activation in asthma.

Electrostatic charge on spacer devices and salbutamol response in young children

Electrostatic charge on plastic spacer devices may affect the efficacy of inhaled drugs, but its consequences have never been evaluated in asthmatic children with airflow limitation. At the end of a positive metacholine challenge, 64 children (51.3+/-12.9 months, 32 boys, specific airway resistance (SRaw) 257.1+/-56.7% and forced expiratory volume in 1s (FEV(1)) 64.2+/-17.9% of the predicted value) inhaled one puff of hydrofluoroalkane-134a (HFA-134a) salbutamol (Ventoline((R))), and 15min later two other puffs (total dose of 300 microgram), delivered through either a new static Babyhaler((R)) (n=21), a detergent-coated, reduced static, Babyhaler((R)) (n=20), or a metal NES-Spacer((R)) (n=23) equipped with facemask. SRaw and FEV(1) were measured after each treatment and compared between groups by a Kruskal-Wallis test. The first 100 microgram salbutamol induced a 151.7+/-43.9% decrease in SRaw and a 19.9+/-10.6% increase in FEV(1). Additional 200 microgram salbutamol allowed a supplementary decrease of 35.1+/-25.7% in SRaw and increase of 12.1+/-11.8% in FEV(1), without significant difference between the spacer devices. Electrostatic charge on spacer devices does not affect bronchodilation with HFA-134a salbutamol in metacholine-challenged pre-school children. This could be in part explained by the use of supramaximal doses of salbutamol.

Glass breaks like metal, but at the nanometer scale

We report in situ atomic force microscopy experiments which reveal the presence of nanoscale damage cavities ahead of a stress-corrosion crack tip in glass. Their presence might explain the departure from linear elasticity observed in the vicinity of a crack tip in glass. Such a ductile fracture mechanism, widely observed in the case of metallic materials at the micrometer scale, might be also at the origin of the striking similarity of the morphologies of fracture surfaces of glass and metallic alloys at different length scales.

Genetic engineering in allotransplantation of vascularized organs

Transplantation offers a unique opportunity for gene transfer into allografts before grafting. After organ retrieval, the cold ischemic period renders organs available for manipulation and gene transfer. Local expression of protective or immunomodulatory molecules within the graft environment offers a better local bioavailability of bioreagents and potentially less systemic side effects. Protection against ischemia-reperfusion injury, acute and/or chronic rejection without significant side effects would be a major breakthrough in transplant research. However, protocols of transfection adapted to the transplant setting and control of gene expression must be clearly evaluated before going to clinical trials. The first part of this review deals with gene transfer techniques into the allograft, emphasizing particular transplant conditions that are encountered and that must be respected when designing protocols for gene transfer experiments. The second part deals with specific therapeutic strategies to protect and prolong allograft survival.

Lethal hepatitis after gene transfer of IL-4 in the liver is independent of immune responses and dependent on apoptosis of hepatocytes: a rodent model of IL-4-induced hepatitis

The putative role of IL-4 in human and animal models of hepatitis has not yet been directly determined. We now report that direct expression of IL-4 in the liver of rats or mice using recombinant adenoviruses coding for rat or mouse IL-4 (AdrIL-4 and AdmIL-4, respectively) results in a lethal, dose-dependent hepatitis. The hepatitis induced by IL-4 was characterized by hepatocyte apoptosis and a massive monocyte/macrophage infiltrate. IL-4-induced hepatitis was independent of T cell-mediated immune responses. Hepatitis occurred even after gene transfer of IL-4 into nude rats, CD8-depleted rats, cyclosporine A-treated rats, or recombinase-activating gene 2(-/-) immunodeficient mice. Peripheral depletion of leukocytes using high doses of cyclophosphamide, and/or the specific depletion of liver macrophages with liposome-encapsulated dichloromethylene diphosphonate in rats did not block lethal IL-4-induced hepatitis. Direct transduction of hepatocytes with adenoviruses was not essential, since injection of AdrIL-4 into the hind limb induced an identical hepatitis. Finally, primary rat hepatocytes in culture also showed apoptosis when cultured in the presence of rIL-4. IL-4-dependent hepatitis was associated with increases in the intrahepatic levels of IFN-gamma, TNF-alpha, and Fas ligand. Administration of AdmIL-4 to IFN-gamma, TNF-alpha receptor type I, or TNF-alpha receptor type II knockout mice also resulted in lethal hepatitis, whereas a moderate protection was observed in Fas-deficient lpr mice. IL-4-dependent hepatocyte apoptosis could be abolished by treatment with caspase inhibitory peptides. Our results thus demonstrate that IL-4 causes hepatocyte apoptosis, which is only partially dependent on the activation of Apo-1-Fas signaling and is largely independent of any immune cells in the liver.

Value of bronchial challenge in scuba diving candidates

Bronchial challenges were effected with carbachol in 76 subjects who were candidates for a scuba diving group. Bronchial reactivity was assessed through airway resistance and forced expiratory volume in 1 sec (FEV1) measurements. Medical interrogation had revealed symptoms of recent (RA) or ancient (AA) asthma, or allergic rhinitis (AL). Nearly half of the subjects (47%) presented bronchial hyperresponsiveness (BHR), which was much more frequent in the RA group, but whose strength did not depend on clinical presentation. Prevalence of BHR was fairly high (36%) in the AL group. BHR constituted a contraindication to scuba diving because it may promote pulmonary barotrauma.

Tolerance to cardiac allografts via local and systemic mechanisms after adenovirus-mediated CTLA4Ig expression

Blockade of the CD28/B7 T cell costimulatory pathway prolongs allograft survival and induces tolerance in some animal models. We analyzed the efficacy of a CTLA4Ig-expressing adenovirus in preventing cardiac allorejection in rats, the mechanisms underlying heart transplant acceptance, and whether the effects of CTLA4Ig were restricted to the graft microenvironment or were systemic. CTLA4Ig gene transfer into the myocardium allowed indefinite graft survival (>100 days vs 9 +/- 1 days for controls) in 90% of cases, whereas CTLA4Ig protein injected systemically only prolonged cardiac allograft survival (by up to 22 days). CTLA4Ig could be detected in the graft and in the serum for at least 1 year after gene transfer. CTLA4Ig gene transfer induced local intragraft immunomodulation at day 5 after transplantation, as shown by decreased expression of the IL-2R and MHC II Ags; decreased levels of mRNA encoding for IFN-gamma, inducible NO synthase, and TGF-beta; and inhibited proliferative responses of graft-infiltrating cells. Systemic immune responses were also down-modulated, as shown by the suppression of Ab production against donor alloantigens and cognate Ags, up to at least 120 days after gene transfer. Alloantigenic and mitogenic proliferative responses of graft-infiltrating cells and total splenocytes were inhibited and were not reversed by IL-2. In contrast, lymph node cells and T cells purified from splenocytes showed normal proliferation. Recipients of long-term grafts treated with adenovirus coding for CTLA4Ig showed organ and donor-specific tolerance. These data show that expression of CTLA4Ig was high and long lasting after adenovirus-mediated gene transfer. This expression resulted in down-modulation of responses against cognate Ags, efficient suppression of local and systemic allograft immune responses, and ultimate induction of donor-specific tolerance.

Changes in maximal performance of inspiratory and skeletal muscles during and after the 7.1-MPa Hydra 10 record human dive

During the 7.1-MPa hydrogen-helium-oxygen record human dive, we tested the hypothesis that the increased ambient pressure would alter the maximal muscle performance, specifically that breathing dense gas would lead to fatigue of the respiratory muscle. A group of hand muscles (adductor pollicis, AP) and the inspiratory muscles (IM) were studied in three professional divers. Maximal voluntary contractions (MVC) of AP and maximal inspiratory pressure (P(i(max))) generated by IM were measured prior to the dive, during compression and decompression, and then 1 and 2 months after the dive. The decrease in MVC (-22%) was significant at 3.1 MPa, i.e. at the beginning of the introduction of hydrogen into the breathing mixture, whereas P(i(max)) fell progressively during the dive and decompression (maximal DeltaP(i(max)) = -55%), a significant reduction still being measured 1 month after the dive. The altered IM function was attributed to the consequences of long-term ventilatory loading, a condition associated with breathing a dense gas. The transient decrease in MVC of the skeletal muscle would indicate a possible effect of the hyperbaric environment, possibly the high partial pressure of hydrogen, on neuromuscular drive.

Interleukin-10 produced by recombinant adenovirus prolongs survival of cardiac allografts in rats

Interleukin-10 (IL-10) and interleukin-4 (IL-4), two Th2-derived cytokines, are molecules with anti-inflammatory and immunodeviating properties whose direct expression in allografts may prolong graft survival. Recombinant adenoviruses represent efficient vectors for gene transfer in quiescent cells in vivo. Adenoviral vectors encoding rat IL-10 (AdIL-10), rat IL-4 (AdIL-4) or beta-galactosidase (AdlacZ) or without transgene (Addl324) were injected directly into rat hearts at the time of transplantation in order to test their potential to prolong heart allograft survival. Expression of vectorized sequences was confirmed in heart biopsies, and kinetic analysis of beta-galactosidase showed transient expression. Cardiac allograft survival was significantly prolonged after administration of 10(9) p.f.u. of AdIL-10 (16.6 +/- 3.2 days, P < 0.05), but not AdIL-4 (9.8 +/- 1.6 days), compared with Addl324-treated (9.3 +/- 3.3 days) or untreated groups (7.8 +/- 1.5 days). Immunohistochemical analysis of allografts after gene transfer of IL-10 showed that leukocyte infiltration was quantitatively equivalent to that seen in control groups but with a strong tendency towards lower levels of CD8+ cells. Importantly, adenovirus-derived IL-10 modified the functional status of leukocytes by inducing a significant decrease in IFN-gamma production but significantly increased transforming-growth factor beta 1 (TGF-beta 1) expression within the grafts compared with those treated with Addl324. These results show that expression of IL-10 by rat hearts after gene transfer mediated by an adenoviral vector decreases allogeneic immune responses and allows prolongation of allograft survival.

Gene therapy in transplantation in the year 2000: moving towards clinical applications?

Transplantation faces several major obstacles that could be overcome by expression of immunomodulatory proteins through application of gene therapy techniques. Gene therapy strategies to prolong graft survival involve gene transfer of immunosuppressive or graft-protecting molecules. Very promising results have been obtained in small animal experimental models with inhibitors of co-stimulatory signals on T cells, immunosuppressive cytokines, donor major histocompatibility antigens and regulators of cell apoptosis or oxidative stress. The application of gene therapy techniques to transplantation offers a great experimental and therapeutic potential. Local production of immunosuppressive molecules may increase their therapeutic efficiency and reduce their systemic effects. When compared with other clinical situations, gene therapy in transplantation offers several potential advantages. Gene transfer into the graft can be performed ex vivo, during the transit between the donor and the recipient, thus avoiding many of the hurdles encountered with in vivo gene transfer. Furthermore, the difficulties associated with immune responses to the gene transfer vectors and transient gene expression may be easier to overcome when gene therapy protocols are applied to transplantation than when applied to other clinical situations. The next century should witness a rapid increase in the application of gene therapy techniques to large animal pre-clinical models of transplantation and later to clinical trials. Gene Therapy (2000) 7, 14-19.

[Protective effect of an apoptosis inhibitor in a new model of hepatitis induced by interleukin-4 in the rat]

OBJECTIVES

Interleukin-4 is a cytokine with pleiotropic effects on many cells. The effects of its expression on the liver remain unclear. To obtain organ-localized cytokine expression and analyze its effect on the liver, recombinant adenovirus with coding sequences of interleukin-4 were transduced to rat livers.

METHODS

Adenovirus with coding sequences of rat interleukin-4 were injected into the portal vein of Wistar rats. Microscopic examination of the liver was performed. The effects of interleukin-4 were confirmed in vitro on primary cultured rat hepatocytes. The same analysis was performed after intraperitoneal injection of l'YVADcmk, an inhibitor of the interleukin 1 converting enzyme.

RESULTS

Interleukin-4 expression due to the recombinant adenovirus produced dose-related, potentially lethal, severe hepatitis. This hepatitis was characterized by a leucocyte infiltrate mainly composed of eosinophilic polymorphonuclear and mast cells with numerous apoptotic hepatocytes. Intraperitoneal injection of YVADcmk decreased hepatocyte apoptosis and biological hepatitis and prevented death.

CONCLUSION

These results suggested that YVADcmk might be used in fulminant hepatitis in which apoptosis is predominant.

M-wave changes after high- and low-frequency electrically induced fatigue in different muscles

The mechanisms of fatigue-induced changes in evoked compound muscle action potential (M-waves) are not well documented. In rats, isolated fast-glycolytic (tibialis anterior, or TA) and slow-oxidative muscles (soleus, or SOL) were stimulated repetitively at a low (10-Hz) or high (80-Hz) rate. Decreased amplitude and prolonged duration of M-waves were only significant after high-frequency fatigue in TA and SOL muscles; that is, in the conditions in which an influx of calcium was measured. On the other hand, maximal force failure and maximal lactic acid increase in the bath medium occurred in TA muscle after high- and low-frequency fatigue trials. Postfatigue increase in potassium concentration occurred in all circumstances. Thus, M-wave alterations depend mainly on the stimulation paradigm and not on the muscle type, and cannot be used as a marker of changes in intracellular potassium or lactate ions. This amplifies understanding of the significance of M-wave changes in human exercise protocols.

Bronchial challenge with carbachol in 3-6-year-old children: body plethysmography assessments

Several studies of airway responsiveness in young children (3-6 years old) have been reported, but few have attempted measurements of airway resistance by body plethysmography. Therefore, we decided to study nonspecific bronchial responsiveness following cumulative doses of inhaled carbachol in 44 children with clinical asthma (CA group), 44 children with chronic cough (CC group), 38 children with wheezy bronchitis in the first 2 years of life (WB group), and 40 controls. Specific airway resistance (sRaw) was measured in a body plethysmograph, and specific airway conductance (sGaw=1/sRaw) was calculated. Two parameters were used to assess individual bronchial responses: 1) PD100 (the dose of carbachol which induced a 100% increase in sRaw), and 2) bronchial reactivity (BR), i.e., the slope of the log-dose sGaw response to carbachol. Significant differences were observed in PD100 and BR between the control group and the three groups of young patients (P < 0.001). Moreover, PD100 of the CA group was significantly lower than in the CC group (83.1 +/- 7.8 microg vs. 108.0 +/- 10.2 microg, respectively, P < 0.05), but was similar to the WB group PD100 (94.4 +/- 8.5 microg). BR in the CA group was significantly higher than in both the CC and WB groups (0.127 +/- 0.009 cm H2O-L.sec(-1) x log microg(-1) vs. 0.073 +/- 0.006 cm H2O(-1) x sec(-1) x log microg(-1) and 0.082 +/- 0.006 cm H2O(-1) x sec(-1) x log microg(-1), respectively, P < 0.001). Repeatability and coefficients of variation were always acceptable. Continuous SaO2 monitoring in some children of the CA group demonstrated the safety of the method, which is proposed as a technique in future studies.

A critical role for transforming growth factor-beta in donor transfusion-induced allograft tolerance

Donor-specific (DST) or nonspecific blood transfusions administered before transplantation can enhance survival of vascularized allografts both in humans and animals but the immunological mechanisms of this effect remain unclear. We have analyzed the expression and the role of endogenous TGF-beta1 in a model of heart allograft tolerance, induced by pregraft DST in adult rats. We reported previously that this tolerance occurs despite a strong infiltration of leukocytes into the graft that are unable to produce both Th1- and Th2-related cytokines in vivo. Allografts from DST-treated rats express high levels of TGF-beta1 mRNA and active protein. This phenomenon is correlated with the rapid infiltration of leukocytes producing high amounts of TGF-beta1. TGF-beta1-producing cells are virtually absent among early infiltrating cells in rejected grafts but are found at a later time point. The induction of allograft tolerance in vivo is abrogated by administration of neutralizing anti-TGF-beta mAb. Moreover, overexpression of active TGF- beta1 in heart allografts using a recombinant adenovirus leads to prolonged graft survival in unmodified recipients. Taken together, our results identify TGF-beta as a critical cytokine involved in the suppression of allograft rejection induced by DST and suggest that TGF-beta-producing regulatory cells are also involved in allograft tolerance.

Blood ammonia and ventilation at maximal exercise

This study, intended to evaluate the role of ammonia (NH3) as a ventilatory stimulus, was conducted in three groups of subjects: 14 sedentary individuals, 12 triathletes, 5 patients with a glycolytic deficiency (Mc Ardle disease). All subjects performed maximal exercise tests on a cycle ergometer. Ventilation measured at maximal oxygen consumption (VE 100%) was correlated with lactatemia (lactate 100%) and ammonemia (NH3 100%) in the sedentary group, but only with ammonemia in triathletes, although NH3 100% and lactate 100% were correlated in both groups, which suggests that correlation between VE 100% and NH3 100% is not a false correlation. In patients with Mc Ardle disease, unable to produce lactate during exercise, VE 100% was correlated with NH3 100%. NH3 may act indirectly by increasing the production of lactate in cereberal tissue. Another hypothesis rests on the fact that the catabolism of ammonia leads to an increase in intracerebral glutamate which may act as a ventilatory stimulus.