Results of ultrathin Descemet stripping automated endothelial keratoplasty with donor corneas preserved in synthetic organ culture media.

PURPOSE: To evaluate outcomes of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) with donor corneas preserved at 31°C in Cornea Syn®, a medium formulated with recombinant human serum albumin (rHSA) to replace foetal calf serum, and deswelled-transported in the xeno-free medium Cornea Trans®. METHODS: Prospective, multicentre, open-label study. We evaluated the endothelial cell loss (ECL) as the percentage variation of the endothelial cell density (ECD, cells/mm2) between 6 and 12 months after surgery, corneal transparency and thickness at 12 months, and adverse events within 12 months. Endothelial lenticules of mean 89 µm, ECD ≥ 2300 cells/mm2, minimum signs of cell mortality or morphology alterations, were dissected by microkeratome in the eye bank, and grafted in patients ≥ 18 years without corneal neovascularisation, conjunctivalization, or blinking impairment. RESULTS: Thirty-five patients underwent UT-DSAEK, 3 showed primary failure, 1 late failure, and 2 skipped the 6-month visit. We analysed data from 29 patients, 27 with Fuchs endothelial corneal dystrophy (FECD) and 2 with pseudophakic bullous keratopathy (PBK). The median ECL between 6 and 12 months was 2.6% (p = .054, CI 0 to 12.5) and the absolute mean (SD) was 158.4 (364.1) cells/mm2. After 12 months, 96.5% of corneas were clear, with mean pachymetry of 585.9 (50.4) µm. CONCLUSIONS: The ECL rate after UT-DSAEK match overall that observed in DSAEK or UT-DSAEK models of endothelial survival and the overall safety compared that reported for similar follow-up. Corneas maintained in Cornea Syn® and Cornea Trans® did not affect the ECD and functional outcomes of UT-DSAEK up to 12 months.

Real-Time PCR Assay for the Detection of Dermatophytes: Comparison between an In-House Method and a Commercial Kit for the Diagnosis of Dermatophytoses in Patients from Dakar, Senegal.

BACKGROUND: PCR assays have been developed for the diagnosis of dermatophytes, yet data in African populations are scarce. OBJECTIVE: This study aimed to compare two PCR assays for the diagnosis of dermatophytosis in outpatients at the Aristide Le Dantec University Hospital in Dakar, Senegal. PATIENTS AND METHODS: A total of 105 samples, including 24 skin, 19 nail and 62 hair samples collected from 99 patients were included in this study. Each sample was subjected to conventional diagnosis (CD), including direct microscopy and culture, and two real-time PCR assays: one in-house (IH)-PCR, used at the University Hospital of Marseille and the Eurobio Scientific commercial kit (CK): designed for the specific detection of six dermatophytes not including Microsporum audouinii. RESULTS: Of the 105 specimens, 24.8%, 36.2% and 20% were positive by CD, IH-PCR and CK-PCR, respectively. The IH-PCR and CK-PCR exhibited 88.9% and 65.4% sensitivity, respectively. With a 36.6 diagnostic odd ratio and 1.41 needed to diagnose, the IH-PCR displayed better diagnostic indices than the CK-PCR. It is notable that, when considering the species that it claims to detect, when it came to skin and nail samples, CK-PCR sensitivity increased to 77%. CONCLUSIONS: The pan-dermatophyte IH-PCR performed better in the diagnosis of dermatophytosis in this African population than the CK-PCR, which is not designed to detect M. audouinii. Nevertheless, both assays exhibited similarly good diagnostic indices for tinea corporis and tinea unguium, both of which are localisations where M. audouinii is more rarely involved than in tinea capitis.

Recombinant human serum albumin for corneal preservation.

PURPOSE: To study the performance of a completely synthetic organ culture (OC) preservation system containing recombinant human serum albumin (rHSA) for preservation of human donor corneas. METHODS: Twenty-four paired donor corneas were randomly collected, and one cornea from each donor was preserved in synthetic (experimental) and serum-based media (control). The tissues were assessed at day 0; after 6 days of preservation at room temperature (RT) in Cornea Trans® and Cornea Prep II® ; after 28 days at 31°C in Cornea Syn® [with rHSA] and Cornea Max® [with foetal calf serum (FCS)] and; 4-day post deswelling in Cornea Trans® and Cornea Jet® . Thickness was determined with optical coherence tomography (OCT) and transparency with a validated, custom device. Morphology, endothelial cell density (ECD) and mortality were observed after treating the tissues with Trypan blue and sucrose. Glucose uptake by the cells was analysed. Data were compared using non-parametric paired Wilcoxon tests with p < 0.05 deemed significant. Histology using periodic acid-schiff (PAS), expressions of p63, CK12, αSMA and ZO-1 were analysed, and cell apoptosis postpreservation was studied. RESULTS: Corneas stored in synthetic media showed a higher and statistically significant value as compared to serum-based media in terms of viable endothelial cell density (VECD), mortality, morphology and glucose uptake postpreservation. Histology showed presence of all the layers, all the markers were expressed, and no apoptosis was observed in either media. CONCLUSION: The new synthetic preservation system containing rHSA (and other confidential constituents) showed better preservation effects than traditional media containing serum.

Bubble technique for Descemet membrane endothelial keratoplasty tissue preparation in an eye bank: air or liquid?

PURPOSE: To compare the big-bubble method using air and liquid as medium of separation for Descemet membrane endothelial keratoplasty (DMEK) lenticule preparation in an eye bank. METHODS: Donor corneas (n=20) were immersed in liquid [tissue culture medium (TCM)]. Air and liquid was injected using a 25-gauge needle in the posterior stroma or as near to the stroma-Descemet membrane (DM) phase as possible to create a complete bubble of larger diameter. The endothelial cell density and mortality were checked pre- and postbubble after deflating the tissue. Four pairs of tissues were used to analyse the intracellular tight junctions and three pairs for histological examination and DNA integrity studies, respectively. RESULTS: The yield obtained using air was 80%, whereas that with liquid was 100%. Single injection was required in six cases; twice in two cases; three and four times in one case each with air bubble, whereas seven cases required single injection; twice in two cases; and thrice in just one case with liquid bubble. The average diameter of the final lenticule was 9.12 (±1.71) mm for air bubble and 9.78 (±1.75) mm for liquid bubble with p=0.4362 (no statistical significance). Endothelial cell mortality postbubble preparation was 8.9 (±12.38)% for air and 6.25 (±9.57)% for liquid (p=0.6268). CONCLUSIONS: DM and endothelium could be separated exclusively using air or liquid bubble. However, liquid bubble seems to have certain advantages over air such as the generation of yield, larger diameter and higher maintenance of endothelial cell density and integrity.

A quantitative method to evaluate the donor corneal tissue quality used in a comparative study between two hypothermic preservation media.

To standardize a new evaluation technique for calculating the overall quality (OQ) of the donor cornea and validate it using a comparative study of corneas preserved in Optisol-GS and Cornea Cold®. Thirty pairs of donor corneas were selected for a 4 week in vitro comparative study using masked observers. Physiological parameters like thickness, transparency, viable endothelial cell density (VECD) and morphology were transformed to numerical range (0-4) to obtain the OQ. Microbiological examination was performed using Bactec instrument. Students t test showed statistically better results (p < 0.05) from week 3 for thickness, week 2 for transparency and week 1 for morphology and VECD; statistical significance (p < 0.05) was found for OQ from week 2 for the corneas preserved in Cornea Cold® compared to Optisol-GS. Epithelial quality was similar regardless of the medium. Microbiological examination showed absence of aerobic and anaerobic microorganisms in both media. OQ method is efficient, consistent and easy, now validated for comparative studies. Further refinement is necessary for its use at eye-banks, bio-banks and research or transplantation purposes. Cornea Cold® is a promising hypothermic corneal storage medium with preservation time ≤21 days. This permits higher flexibility, evaluation accuracy, longer duration for surgical preparation and ease of transportation.

Semaphorin 3E suppresses tumor cell death triggered by the plexin D1 dependence receptor in metastatic breast cancers.

The semaphorin guidance molecules and their receptors, the plexins, are often inappropriately expressed in cancers. However, the signaling processes mediated by plexins in tumor cells are still poorly understood. Here, we demonstrate that the Semaphorin 3E (Sema3E) regulates tumor cell survival by suppressing an apoptotic pathway triggered by the Plexin D1 dependence receptor. In mouse models of breast cancer, a ligand trap that sequesters Sema3E inhibited tumor growth and reduced metastasis through a selective tumor cytocidal effect. We further showed that Plexin D1 triggers apoptosis via interaction with the orphan nuclear receptor NR4A1. These results define a critical role of Sema3E/Plexin D1 interaction in tumor resistance to apoptosis and suggest a therapeutic approach based on activation of a dependence receptor pathway.

Dynamic quantitative intravital imaging of glioblastoma progression reveals a lack of correlation between tumor growth and blood vessel density.

The spatiotemporal and longitudinal monitoring of cellular processes occurring in tumors is critical for oncological research. We focused on glioblastoma multiforme (GBM), an untreatable highly vascularized brain tumor whose progression is thought to critically depend on the oxygen and metabolites supplied by blood vessels. We optimized protocols for orthotopic GBM grafting in mice that were able to recapitulate the biophysical constraints normally governing tumor progression and were suitable for intravital multiphoton microscopy. We repeatedly imaged tumor cells and blood vessels during GBM development. We established methods for quantitative correlative analyses of dynamic imaging data over wide fields in order to cover the entire tumor. We searched whether correlations existed between blood vessel density, tumor cell density and proliferation in control tumors. Extensive vascular remodeling and the formation of new vessels accompanied U87 tumor cell growth, but no strong correlation was found between local cell density and the extent of local blood vessel density irrespective of the tumor area or time points. The technique moreover proves useful for comparative analysis of mice subjected either to Bevacizumab anti-angiogenic treatment that targets VEGF or to AMD3100, an antagonist of CXCR4 receptor. Bevacizumab treatment massively reduced tumoral vessel densities but only transiently reduced U87 tumor growth rate. Again, there was no correlation between local blood vessel density and local cell density. Moreover, Bev applied only prior to tumor implantation inhibited tumor growth to the same extent as post-grafting treatment. AMD3100 achieved a potent inhibition of tumor growth without significant reduction in blood vessel density. These results indicate that in the brain, in this model, tumor growth can be sustained without an increase in blood vessel density and suggest that GBM growth is rather governed by stromal properties.

NCAM180 regulates Ric8A membrane localization and potentiates ß-adrenergic response.

Cooperation between receptors allows integrated intracellular signaling leading to appropriate physiological responses. The Neural Cell Adhesion Molecule (NCAM) has three main isoforms of 120, 140 and 180 kDa, with adhesive and signaling properties, but their respective functions remains to be fully identified. Here we show that the human NCAM180 intracellular domain is a novel interactor of the human guanosine exchange factor (GEF) Ric8A using the yeast two hybrid system and immunoprecipitation. Furthermore, NCAM, Ric8A and G(αs) form a tripartite complex. Colocalization experiments by confocal microscopy revealed that human NCAM180 specifically induces the recruitment of Ric8A to the membrane. In addition, using an in vitro recombinant system, and in vivo by comparing NCAM knock-out mouse brain to NCAM heterozygous and wild type brains, we show that NCAM expression dose dependently regulates Ric8A redistribution in detergent resistent membrane microdomains (DRM). Previous studies have demonstrated essential roles for Ric8 in G(α) protein activity at G protein coupled receptors (GPCR), during neurotransmitter release and for asymmetric cell division. We observed that inhibition of Ric8A by siRNA or its overexpression, decreases or increases respectively, cAMP production following ß-adrenergic receptor stimulation. Furthermore, in human HEK293T recombinant cells, NCAM180 potentiates the G(αs) coupled ß-adrenergic receptor response, in a Ric8A dependent manner, whereas NCAM120 or NCAM140 do not. Finally, in mouse hippocampal neurons expressing endogenously NCAM, NCAM is required for the agonist isoproterenol to induce cAMP production, and this requirement depends on Ric8A. These data illustrate a functional crosstalk between a GPCR and an IgCAM in the nervous system.

Polysialic acid neural cell adhesion molecule (PSA-NCAM) is an adverse prognosis factor in glioblastoma, and regulates olig2 expression in glioma cell lines.

BACKGROUND: Glioblastoma multiforme (GBM) is the most aggressive and frequent brain tumor, albeit without cure. Although patient survival is limited to one year on average, significant variability in outcome is observed. The assessment of biomarkers is needed to gain better knowledge of this type of tumor, help prognosis, design and evaluate therapies. The neurodevelopmental polysialic acid neural cell adhesion molecule (PSA-NCAM) protein is overexpressed in various cancers. Here, we studied its expression in GBM and evaluated its prognosis value for overall survival (OS) and disease free survival (DFS). METHODS: We set up a specific and sensitive enzyme linked immunosorbent assay (ELISA) test for PSA-NCAM quantification, which correlated well with PSA-NCAM semi quantitative analysis by immunohistochemistry, and thus provides an accurate quantitative measurement of PSA-NCAM content for the 56 GBM biopsies analyzed. For statistics, the Spearman correlation coefficient was used to evaluate the consistency between the immunohistochemistry and ELISA data. Patients' survival was estimated by using the Kaplan-Meier method, and curves were compared using the log-rank test. On multivariate analysis, the effect of potential risk factors on the DFS and OS were evaluated using the cox regression proportional hazard models. The threshold for statistical significance was p = 0.05. RESULTS: We showed that PSA-NCAM was expressed by approximately two thirds of the GBM at variable levels. On univariate analysis, PSA-NCAM content was an adverse prognosis factor for both OS (p = 0.04) and DFS (p = 0.0017). On multivariate analysis, PSA-NCAM expression was an independent negative predictor of OS (p = 0.046) and DFS (p = 0.007). Furthermore, in glioma cell lines, PSA-NCAM level expression was correlated to the one of olig2, a transcription factor required for gliomagenesis. CONCLUSION: PSA-NCAM represents a valuable biomarker for the prognosis of GBM patients.

A polysialic acid mimetic peptide promotes functional recovery in a mouse model of spinal cord injury.

Contrary to lower species that recapitulate some of the developmental programs, in mammals, functional recovery after spinal cord injury is impaired by a non-permissive environment and the lack of plasticity of adult neurons. The developmental plasticity associated linear homopolymer of alpha 2,8-linked sialic acid (PolySialic Acid, PSA), represents a permissive determinant that could contribute to recovery. We previously showed that a PSA cyclic mimetic peptide (PR-21) displayed PSA-like biological functions (Torregrossa, P., Buhl, L., Bancila, M., Durbec, P., Schafer, C., Schachner, M., Rougon, G., 2004. Selection of poly-alpha 2,8-sialic acid mimotopes from a random phage peptide library and analysis of their bioactivity. J. Biol. Chem. 279, 30707-30714.). In the present study we investigated the therapeutic potential of PR-21 in young adult mice after dorsal hemisection at the T9 level. We show that PR-21 fulfills several criteria for an in vivo use as it is not toxic, not immunogenic and displays good stability in biological fluids or tissue. Delivery of PR-21 to the lesion site decreased the time of the animals' return to continence, and enhanced motor functions, sensorimotor control and coordination of hindlimbs with forelimbs when compared to a control peptide. At the cellular level, PR-21 increased serotonergic axon density at and caudal to the lesion site, and decreased reactive gliosis in vivo. In an in vitro model of reactive astrocytes, PR-21 increased NCAM expression in strongly GFAP positive cells. Our data point to the unique features of a carbohydrate mimicking peptide, and support the notion that PSA can be considered as an important factor in recovery from spinal cord injury.

Polysialylation increases lateral diffusion of neural cell adhesion molecule in the cell membrane.

Polysialic acid (PSA) is a polymer of N-acetylneuraminic acid residues added post-translationally to the membrane-bound neural cell adhesion molecule (NCAM). The large excluded volume created by PSA polymer is thought to facilitate cell migration by decreasing cell adhesion. Here we used live cell imaging (spot fluorescence recovery after photobleaching and fluorescence correlation spectroscopy) combined with biochemical approaches in an attempt to uncover a link between cell motility and the impact of polysialylation on NCAM dynamics. We show that PSA regulates specifically NCAM lateral diffusion and this is dependent on the integrity of the cytoskeleton. However, whereas the glial-derivative neurotrophic factor chemotactic effect is dependent on PSA, the molecular dynamics of PSA-NCAM is not directly affected by glial-derivative neurotrophic factor. These findings reveal a new intrinsic mechanism by which polysialylation regulates NCAM dynamics and thereby a biological function like cell migration.

Peptidoglycan and bacterial DNA induce inflammation and coagulation markers in synergy.

Bacterial compounds signal the presence of foreign pathogens in the innate immune system. These microbial components are key players in infectious diseases and implicate toll-like receptors in the activation of inflammation and coagulation. Nevertheless, the existence of a synergistic relationship between peptidoglycan and bacterial DNA on these two physiological responses has not been investigated. The present study reports new findings on the regulation of tumor necrosis factor alpha and tissue factor in peripheral blood mononuclear cells by peptidoglycan and bacterial DNA. These were found to induce tumor necrosis factor alpha and tissue factor simultaneously and in a synergistic manner. These findings provide a new proinflammatory and procoagulant mechanism likely to play a role in sepsis pathogenesis.

Characterization of the DialGuard device for endotoxin removal in hemodialysis.

Bacterial pyrogens, capable of penetrating dialyzer membranes, are responsible for a systemic inflammatory reaction in hemodialysis patients. Dialyzer reuse, involving rinsing of the dialyzer with pyrogen-containing water, may exacerbate this situation. Studies of the mechanism of action of endotoxin suggest that it irreversibly damages the vascular endothelium. The novel endotoxin removal method described here, is based on affinity-binding of endotoxin by the adsorbent ClarEtox, a USP Class VI-certified resin that is the active component of the medical device DialGuard. Under standard hemodialysis operating conditions, challenge of DialGuard with Pseudomonas maltophilia supernatant-spiked dialysate, containing 35-193 EU/ml endotoxin, resulted in endotoxin levels below 0.05 EU/ml in the treated dialysate. DialGuard was able to decrease endotoxin concentrations in the dialysate from a range of 2.39-8.49 to <0.005 EU/ml. DialGuard supports high fluid velocities at low back pressures and can be sanitized using the heat sanitization cycle of hemodialysis machines. DialGuard offers a simple, user-friendly way to reduce the concentration of endotoxin in dialysate and water for dialysis at a low cost.

A new method for removing endotoxin from plasma using hemocompatible affinity chromatography technology, applicable for extracorporeal treatment of septic patients.

The pathogenesis of sepsis begins with the proliferation of micro-organisms at a site of infection, followed by invasion of the bloodstream and other organs. Gram-negative bacteria account for a large part of sepsis cases. The structural component of Gram-negative bacteria, endotoxin or lipopolysaccharide (LPS), induces the synthesis and release of endogenous mediators of sepsis. A growing number of investigations of the molecular mechanisms occurring in sepsis, point to endotoxin as a central mediator leading to multi-organ failure and death. In numerous clinical trials, attempts to target molecules downstream of endotoxin have been made, but have not been associated with improved survival. We describe an affinity-based system for the selective removal of endotoxin from plasma. The small-scale device, a 1.5 ml cartridge, contains beads that bind endotoxin with high specificity and efficiency. In addition, evidence is presented that this device does not affect plasma hemostasis, nor does it activate the complement system. Taken together, these results represent a proof of principle for endotoxin removal from plasma, which may be of clinical value to treat sepsis by extracorporeal circulation of the blood through a scaled-up version of this endotoxin-removing device.