High time resolution measurements of droplet evaporation kinetics and particle crystallisation.

A refined technique for observing the complete evaporation behaviour of free-falling droplets, from droplet generation to complete solvent evaporation, with ultra-high time resolution is introduced and benchmarked. High-resolution phase-delay stroboscopic imaging is employed to simultaneously resolve the evolving droplet morphology, geometric and aerodynamic diameters, throughout the evaporative lifetime with a user-controlled < µs timescale. This allows rapid, complex morphological changes, such as crystallisation events, to be clearly observed and the corresponding mechanisms to be inferred. The dried particles are sampled for offline SEM analysis and the observed morphologies compared to the inflight imaging. Density changes can be calculated directly from the deviation between the geometric and aerodynamic diameters. The full capabilities of the new technique are demonstrated by examination of the different evaporation behaviours and crystallisation mechanisms for aqueous sodium chloride droplets evaporating under different ambient relative humidity (RH) conditions. The crystallisation window, defined as the time taken from initial to complete crystallisation, is shown to be RH dependent, extending from 0.03 s at 20% RH and 0.13 s at 40% RH. The different crystallisation mechanisms observed during the experiments are also clearly reflected in the final structure of the dry particles, with multi-crystal structures produced at low RH compared to single-crystal structures at higher RH. It is anticipated that this technique will unlock measurements which explore the evaporation behaviour and crystallisation mechanisms for rapid, complex droplet drying events, and with increasingly non-ideal solutions, relevant to industrial applications.

Interferometric out-of-focus imaging of ice particles with overlapping images.

It is shown that the size and relative positions of two irregular rough particles can be analyzed using interferometric out-of-focus imaging despite the overlapping of their out-of-focus images. Simulations are confirmed by experiments done with ice particles generated in a freezing column.

Simultaneous 3D location and size measurement of bubbles and sand particles in a flow using interferometric particle imaging.

We present a system to characterize a triphasic flow in a 3D volume (air bubbles and solid irregular particles in water) using only one CCD sensor. A cylindrical interferometric out-of-focus imaging setup is used to determine simultaneously the 3D position and the size of bubbles and irregular sand particles in a flow. The 3D position of the particles is deduced from the ellipticity of their out-of-focus image. The size of bubbles is deduced from analysis of interference fringes. The characteristics of irregular sand particles are obtained from analysis of their speckle-like pattern. Experiments are confirmed by simulations.

Cyclosporine A drives a Th17- and Th2-mediated posttransplant obliterative airway disease.

Calcineurin-inhibitor refractory bronchiolitis obliterans (BO) represents the leading cause of late graft failure after lung transplantation. T helper (Th)2 and Th17 lymphocytes have been associated with BO development. Taking advantage of a fully allogeneic trachea transplantation model in mice, we addressed the pathogenicity of Th cells in obliterative airway disease (OAD) occurring in cyclosporine A (CsA)-treated recipients. We found that CsA prevented CD8(+) T cell infiltration into the graft and downregulated the Th1 response but affected neither Th2 nor Th17 responses in vivo. In secondary mixed lymphocyte cultures, CsA dramatically decreased donor-specific IFN-γ production, enhanced IL-17 production and did not affect IL-13. As CD4(+) depletion efficiently prevented OAD in CsA-treated recipients, we further explored the role of Th2 and Th17 immunity in vivo. Although IL-4 and IL-17 deficient untreated mice developed an OAD comparable to wild-type recipients, a single cytokine deficiency afforded significant protection in CsA-treated recipients. In conclusion, CsA treatment unbalances T helper alloreactivity and favors Th2 and Th17 as coexisting pathways mediating chronic rejection of heterotopic tracheal allografts.

CTLA4-Ig restores rejection of MHC class-II mismatched allografts by disabling IL-2-expanded regulatory T cells.

Allograft acceptance and tolerance can be achieved by different approaches including inhibition of effector T cell responses through CD28-dependent costimulatory blockade and induction of peripheral regulatory T cells (Tregs). The observation that Tregs rely upon CD28-dependent signals for development and peripheral expansion, raises the intriguing possibility of a counterproductive consequence of CTLA4-Ig administration on tolerance induction. We have investigated the possible negative effect of CTLA4-Ig on Treg-mediated tolerance induction using a mouse model of single MHC class II-mismatched skin grafts in which long-term acceptance was achieved by short-term administration of IL-2/anti-IL-2 complex. CTLA4-Ig treatment was found to abolish Treg-dependent acceptance in this model, restoring skin allograft rejection and Th1 alloreactivity. CTLA4-Ig inhibited IL-2-driven Treg expansion, and prevented in particular the occurrence of ICOS(+) Tregs endowed with potent suppressive capacities. Restoring CD28 signaling was sufficient to counteract the deleterious effect of CTLA4-Ig on Treg expansion and functionality, in keeping with the hypothesis that costimulatory blockade inhibits Treg expansion and function by limiting the delivery of essential CD28-dependent signals. Inhibition of regulatory T cell function should therefore be taken into account when designing tolerance protocols based on costimulatory blockade.

[Study of mechanisms dependent on interleukin-17 and their modulation in development of bronchiolitis obliterans after experimental transplantation]. / Etude des mécanismes dépendants de l'interleukine-17 et de leur modulation dans le développement de la bronchiolite oblitérante expérimentale après transplantation.

Survival of lung transplant recipients is currently limited by the primary graft dysfunction, an acute phenomenon occurring within 72 hours after the transplantation, but also by the chronic rejection that appears more than one year later. IL-17 might be implicated in these two diseases. The heterotopic trachea transplantation in mice generates epithelial lesions mimicking the human pathology. Using this model, we show that IL-17 was crucially implicated in early, but not chronic lesions after transplantation. The main intragraft cellular sources of IL-17 are recipient-derived gammadelta T cells. However, the IL17-dependent lesions in our model are not mediated by a direct effect of IL-17 on donor-derived cells. Nevertheless, its inhibition protects CK-14+ basal epithelial stem cells that are known to be capable of renewing of the whole epithelium.

Endotoxin-induced myeloid-derived suppressor cells inhibit alloimmune responses via heme oxygenase-1.

Inflammation and cancer are associated with impairment of T-cell responses by a heterogeneous population of myeloid-derived suppressor cells (MDSCs) coexpressing CD11b and GR-1 antigens. MDSCs have been recently implicated in costimulation blockade-induced transplantation tolerance in rats, which was under the control of inducible NO synthase (iNOS). Herein, we describe CD11b+GR-1+MDSC-compatible cells appearing after repetitive injections of lipopolysaccharide (LPS) using a unique mechanism of suppression. These cells suppressed T-cell proliferation and Th1 and Th2 cytokine production in both mixed lymphocyte reaction and polyclonal stimulation assays. Transfer of CD11b+ cells from LPS-treated mice in untreated recipients significantly prolonged skin allograft survival. They produced large amounts of IL-10 and expressed heme oxygenase-1 (HO-1), a stress-responsive enzyme endowed with immunoregulatory and cytoprotective properties not previously associated with MDSC activity. HO-1 inhibition by the specific inhibitor, SnPP, completely abolished T-cell suppression and IL-10 production. In contrast, neither iNOS nor arginase 1 inhibition did affect suppression. Importantly, HO-1 inhibition before CD11b+ cell transfer prevented the delay of allograft rejection revealing a new MDSC-associated suppressor mechanism relevant for transplantation.

A new technique for measuring blood flow in polytetrafluorethylene grafts for hemodialysis.

A method has been described for the measurement of blood flow in non branching grafts using the isotope dilution principle. The technique is simple, reproducible and consistent and can be performed in less than ten minutes.

Hemodynamic studies in patients with expanded polytetrafluoroethylene (PTFE) forearm grafts.

21 patients with polytetrafluoroethylene grafts inserted for hemodialysis access were studied to assess the hemodynamic parameters. Mean graft flow was 1.9 l/min with a range of 0.2-3.8 l/min. Intragraft pressure varied from 1 to 83 mmHg and was dependent on systemic pressure, graft flow and the presence of stenotic lesions. Mean cardiac output was 7.1 l/min and index 4.0 l/min and was positively correlated with graft flow. By obtaining this data surgical corrective action was taken in several patients prospectively thus removing the abnormalities and ensuring continued graft patency. The techniques described are reproducible and simple and can be carried out in less than five minutes with minimal patient discomfort or hazard.

Polytetrafluorethylene (PTFE) grafts for hemodialysis. 18 months' experience.

18 months clinical experience with 6 mm polytetrafluorethylene forearm grafts for hemodialysis access has been described. 35 grafts were implanted, all in patients who had unsuitable vessels for construction of a regular Brescia-Cimino forearm fistula. The overall patency was 71% with mean duration of 10.3 months, and at any one time more than 85% of the grafts at risk were functional. Complications, including undesirable flow rates, edema, thrombosis, aneurysm and cardiac failure have been discussed and rational methods of avoidance described. We believe the polytetrafluorethylene (PTFE) graft represents an important advance in hemodialysis access.

Impact of interleukin-2-expanded regulatory T cells in various allogeneic combinations on mouse skin graft survival.

The impact of in vivo regulatory T cells (Treg) expansion using short-term injections of interleukin-2 (IL-2) coupled to a specific anti-IL-2 antibody was examined in various allogeneic combinations of murine skin transplantations. In a model of a single major histocompatibility complex (MHC) class II disparity, the IL-2-expanded Tregs infiltrated the transplanted skin, inhibited Th1 alloreactivity, and prevented acute graft rejection. However, in the presence of increased load of CD4-recognized alloantigens, exogenous IL-2 only moderately prolonged graft survival as attested by CD8 T cell-depletion in full minor plus major mismatched recipients treated with IL-2. If direct CD8 alloreactivity remained intact, the IL-2/anti-IL-2-mediated Tregs expansion failed to delay allograft rejection. This observation was confirmed by the inability of expanded Tregs to delay rejection of multiple minor disparate (MHC matched) skin allografts. Altogether, these results warn that cross-reactive CD8(+) T cells represent an important hurdle to Treg-based tolerance induction.

Carpegen real-time polymerase chain reaction vs. anaerobic culture for periodontal pathogen identification.

BACKGROUND/AIMS: The aim of this study was to compare two methods of microbiological diagnosis, anaerobic bacterial culture and real-time polymerase chain reaction (PCR), for the detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Treponema denticola. METHODS: Seventy-two samples were collected from 18 patients who were suffering from aggressive periodontitis. The data obtained were compared for the two methods. RESULTS: The results obtained with real-time PCR were different from those obtained with bacterial culture. The detection differences were 3% for A. actinomycetemcomitans, 8.33% for P. intermedia, and 12.5% for F. nucleatum. However, the differences for P. gingivalis and T. forsythia were 51.39% and 36.11%, respectively. No comparison was possible for T. denticola because it cannot be identified in culture. The variations found were the result of the better detection level (10(2) pathogens) of the PCR probe. Unlike bacterial culture, PCR allows the detection of T. denticola, which does not forming colonies and is oxygen sensitive. For F. nucleatum, T. forsythia and P. gingivalis, the real-time PCR technique was more sensitive than culture. CONCLUSION: Good results were obtained with the real-time PCR technique for the six periopathogens targeted. This method seems to be indicated for its simplicity, rapidity and reproducibility but it cannot analyze data for an antibiotic susceptibility test. The periodontist must therefore choose one of these two methods according to his specific clinical objective: to obtain rapid, specific detection even with weak initial concentrations (but for targeted periopathogens only) or to be non-specific and analyze the pathological activity with an antibiogram.

Acinetobacter baumanii folliculitis in a patient with AIDS.

Gram-negative folliculitis usually involves the face and develops in patients with acne or rosacea during long-term antibiotic therapy. Numerous pathogens have been found, but not, until now, Acinetobacter baumanii which has previously been recognized as an important cause of nosocomial infections and hospital outbreaks. We report here a case of A. baumanii folliculitis of the face, neck, arms and upper part of trunk in a patient with AIDS responding to intravenous treatment with ticarcillin-clavulanic acid. The bacterium was not found on healthy skin and the source of the infection remained unknown.

[The role of chlorhexidine irrigation combined with ultrasonic root planing in treatment of periodontal disease. Preliminary study]. / Intérêt de l'association d'une irrigation à la chlorhexidine et du surfaçage ultrasonique dans le traitement des maladies parodontales. Etude préliminaire.

The beneficial effects of chlorhexidine on plaque formation have been well documented. This study was undertaken to evaluate the dual effects of chlorhexidine irrigation and root planing with an ultrasonic scaler. The parameters measured were plaque and gingival indices and bleeding on probing. A statistically significant decrease in all indices measured was demonstrated when compared with the test group of patients who received ultrasonic scaling and irrigation with sterile water.

Complications in expanded polytetrafluoroethylene arteriovenous grafts: an angiographic study.

Expanded polytetrafluoroethylene grafts were used for creation of arteriovenous shunts in 35 patients on chronic hemodialysis. When flow studies or mechanical factors indicated abnormal flow in the graft, angiography was performed. Detection of venous backflow or obstruction, arterial stenosis, aneurysm formation, or graft kinking facilitated correction and thus salvage of the grafts.