Diabetic retinopathy: new therapeutic perspectives based on pathogenic mechanisms.

Diabetic retinopathy (DR) is the leading cause of visual impairment and preventable blindness and represents a significant socioeconomic cost for healthcare systems worldwide. In early stages of DR the only therapeutic strategy that physicians can offer is a tight control of the risk factors for DR (mainly blood glucose and blood pressure). The currently available treatments for DR are applicable only at advanced stages of the disease and are associated with significant adverse effects. Therefore, new treatments for the early stages of DR are needed. However, in early stages of DR invasive treatments such as intravitreal injections are too aggressive, and topical treatment seems to be an emerging route. In the present review, therapeutic strategies based on the main pathogenic mechanisms involved in the development of DR are reviewed. The main gap in the clinical setting is the treatment of early stages of DR and, therefore, this review emphasizes in this issue by giving an overview of potential druggable targets. By understanding of disease-specific pathogenic mechanisms, biological heterogeneity and progression patterns in early and advanced DR a more personalised approach to patient treatment will be implemented.

Usefulness of Ultrasound in Assessing the Impact of Bariatric Surgery on Body Composition: a Pilot Study.

BACKGROUND: Bariatric surgery (BS) has a significant impact on body composition. The purpose of the study is to evaluate the usefulness of musculoskeletal ultrasound (MUS) to bioelectrical impedance (BIA) in the follow-up of patients undergoing BS in terms of body composition and quality of life (QoL). METHODS: This is a prospective pilot study including 32 subjects (75% female, mean age: 49.15 ± 1.9 years) who underwent BS. Fat mass (FM), lean mass (LM), and skeletal muscle index (SMI) were calculated by BIA. MUS measured subcutaneous fat (SF) and thigh muscle thickness (TMT) of the quadriceps. QoL was assessed by the Moorehead-Ardelt questionnaire. All these measurements were performed 1 month prior to BS and at 12-month follow-up. RESULTS: The mean BMI decreased by 6.63 ± 1.25 kg/m2 (p=0.001). We observed significant reductions in FM (p=0.001) and SF (p=0.007) and in LM (p=0.001) but not in SMI and TMT. We found a correlation between the FM and SF (pre-surgical, r=0.42, p=0.01; post-surgical, r=0.52, p=0.003) and between SMI and TMT (pre-surgical, r=0.35, p=0.04; post-surgical, r=0.38, p=0.03). QoL test showed significant improvement (p=0.001). In addition, a correlation between the QoL questionnaire and TMT post-surgery (r=0.91, p=0.019) was observed. However, we did not find any statistically significant correlation between QoL assessment and SMI or LM. CONCLUSIONS: Our results suggest that MUS can be complementary to BIA for the evaluation and the follow-up of body composition after BS. TMT of quadriceps can provide relevant information about regional sarcopenia and has a significant correlation with QoL.

A quantitative indirect ELISA to monitor the effectiveness of rabies vaccination in domestic and wild carnivores.

This paper reports a new ELISA to measure the level of rabies anti-glycoprotein G antibodies after vaccination. The Platelia Rabies II kit was evaluated on different populations of dogs, cats and foxes. For each target species, sera from naive, unvaccinated and vaccinated animals were tested. Platelia Rabies II results were compared to the reference fluorescent antibody virus neutralisation test (for dogs and cats) and to a published in house ELISA test (for foxes). The Platelia Rabies II test was found to be highly specific whatever the species (more than 98%) using a cut-off value of 0.5 EU/ml. The index of sensitivity was between 92.4% and 94.5% for fox samples, and reached 83% for domestic carnivores. Data collected by testing field samples revealed that the rate of false negative results ranged between 8.9% and 11.1% and the rate of false positive results ranged between 1% and 2% for the dog/cat population. Therefore, the Platelia Rabies II test described here would be a good candidate for routine detection of rabies antibodies not only in domestic carnivores (within the framework of international trade) but also in foxes for the follow up of rabies oral vaccination programs.

Collaborative study to evaluate a new ELISA test to monitor the effectiveness of rabies vaccination in domestic carnivores.

To prevent any introduction of rabies, many rabies-free countries have adopted a scheme requiring the rabies vaccination of pets associated with a serological test. FAVN test and RFFIT are the current OIE prescribed techniques to perform this assay. A qualitative indirect ELISA (Serelisa) test has been recently described as a screening test to monitor the effectiveness of rabies vaccination of pets. A lack of sensitivity requires ELISA negative samples to be retested using an OIE confirmatory test. This raised the question whether this new test could be reasonably proposed as an alternative tool in the context of international trades of pets. The Community Reference Institute of Nancy organized a short trial to answer this question. In this study, 16 laboratories tested a panel of their own samples with FAVN test/RFFIT and the Serelisa. The comparison of results revealed that the performance of the Serelisa is highly heterogeneous. A lack of sensitivity was detected in 50% of participants, when 25% of laboratories obtained a significant rate of false positive results. This last point questions the pertinence of using the Serelisa in the context of international trades by preventing any movements of insufficiently or non-protected animals.

Tools for rabies serology to monitor the effectiveness of rabies vaccination in domestic and wild carnivores.

Serology remains the only way to monitor the effectiveness of vaccination of humans and animals against rabies. Many techniques for determining the level of rabies antibodies have been described, including seroneutralisation techniques such as tests for fluorescent antibody virus neutralisation (FAVN) and rapid fluorescent focus inhibition (RFFIT), enzyme-linked immunosorbent assay (ELISA), and in-vivo tests (the mouse neutralisation test, MNT). The need to verify the effectiveness of rabies vaccination has become widespread, particularly in the context of international trading of domestic carnivores from infected to rabies-free territories. The standardisation of serological techniques, approval of laboratories and proficiency tests are key concepts to ensure the practicability of such systems. Serological tests for rabies are also often used by laboratories in infected territories to assess the efficacy of campaigns aimed at the eradication of the disease via oral vaccination of wildlife. The adaptation of these methods should provide the means to titrate specific antibodies in dogs during mass parenteral vaccination in countries infected by canine rabies. However, in most cases these serological tests are carried without any standardised procedure. On the basis of our experience in rabies serology and its harmonisation throughout laboratories worldwide, we propose here an adapted standard technique for the serological monitoring for rabies in wildlife at the European level. Such harmonisation would allow the monitoring of vaccination campaigns to be enhanced by increasing the exchange of epidemiological data, with the ultimate goal being the eradication of rabies in Europe.

First isolation of a rabid bat infected with European bat lyssavirus in Luxembourg.

Rabid bats are regularly reported in Europe, especially in countries that have implemented a bat surveillance network. In May 2013, bat rabies was evidenced for the first time in Luxembourg (southern city of Differdange). The rabies virus, an EBLV-1b strain, was diagnosed in a serotine bat that bit a 29-year-old male person while he was asleep. The man received rapidly a post-exposure RABV treatment and was put under strict medical supervision.

Development of a qualitative indirect ELISA for the measurement of rabies virus-specific antibodies from vaccinated dogs and cats.

A protocol suitable for the detection of rabies virus-specific antibodies in serum samples from companion animals using an enzyme linked immunosorbent assay (ELISA) is described. This method has been used successfully for the qualitative assessment of rabies virus-specific antibodies in serum samples from a cohort of vaccinated dogs and cats. In two initial field studies, a variable population of field samples from the Veterinary Laboratories Agency (VLA), United Kingdom were tested. In the first study (n = 1000), the number of false-positive and false-negative results was 11 samples (1.1%) and 67 samples (6.7%), respectively. In the second study (n = 920), the number of false-positive and false-negative results was 7 samples (0.8%) and 52 samples (5.7%). In a third study, undertaken at l'Agence Française de Sécurité Sanitaire des Aliments (AFSSA), Nancy, France (n = 440), 1 false-positive sample (0.23%) and 91 (20.7%) false-negative samples were identified. Data generated using this prototype ELISA indicate a strong correlation for specificity when compared to the gold standard fluorescent antibody virus neutralisation (FAVN) test. Although the ELISA has a lower sensitivity than the FAVN test, it is a useful tool for rapidly screening serum samples from vaccinated companion animals. Using a cut-off value of 0.6 EU/ml, the sensitivity (R = % from VLA and 79% from AFSSA) and specificity (R = 97.3%) indices between the ELISA compared favourably with data generated using the FAVN test. The major advantages of the ELISA test are that it is a qualitative tool that can be completed in four hours, does not require the use of live virus and can be performed without the need for specialised laboratory containment. This contrasts with 4 days using conventional rabies antibody virus neutralisation assays. Using the current format, the ELISA assay described would be a valuable screening tool for the detection of rabies antibodies from vaccinated domestic animals in combination with other Office International des Epizooties (OIE) accepted serological tests.

Neutralising antibody titration in 25,000 sera of dogs and cats vaccinated against rabies in France, in the framework of the new regulations that offer an alternative to quarantine.

Regulations governing international movements of domestic carnivores from rabies-infected to rabies-free countries have recently been loosened, with the adoption of a system that combines vaccination against rabies and serological surveillance (neutralising antibody titration test with a threshold of 0.5 UI/ml). Since 1993, the Research Laboratory for Rabies and Wild Animal Pathology in Nancy, France, has analysed over 25,000 sera from dogs and cats using a viral seroneutralisation technique. The statistical analyses performed during this time show that cats respond better than dogs. Although no significant difference in titres was observed between primovaccinated and repeat-vaccinated cats, repeat-vaccinated dogs had titres above 0.5 IU/ml more frequently. In primovaccinated dogs, monovalent vaccines offered a better serological conversion rate than multivalent ones. Finally, the results of these analyses showed a strong correlation between antibody counts and the time that elapsed between the last vaccination and the blood sampling.

Comparative assay of fluorescent antibody test results among twelve European National Reference Laboratories using various anti-rabies conjugates.

Twelve National Reference Laboratories (NRLs) for rabies have undertaken a comparative assay to assess the comparison of fluorescent antibody test (FAT) results using five coded commercial anti-rabies conjugates (Biorad, Bioveta, Fujirebio, Millipore, and SIFIN conjugates). Homogenized positive brain tissues infected with various lyssavirus species as well as negative samples were analyzed blindly using a standardized FAT procedure. Conjugates B, C, D, and E were found to be significantly more effective than conjugate A for GS7 (French RABV) diluted samples (1/8 and 1/100) while the frequency of concordant results of conjugates C and D differ significantly from conjugates A, B and E for CVS 27. For detection of EBLV-1 strains, conjugates C and D also presented a significantly lower frequency of discordant results compared to conjugates A, B and E. Conjugates B, C and D were found to be significantly more effective than conjugates E and A for EBLV-2 and ABLV samples. In view of these results, conjugates C and D set themselves apart from the others and appeared as the most effective of this 5-panel conjugates. This study clearly demonstrates that the variability of conjugates used by National Reference Laboratories can potentially lead to discordant results and influence assay sensitivity. In case of false negative results this could have a dramatic impact if the animal under investigation is responsible for human exposure. To avoid such situations, confirmatory tests should be implemented.

International interlaboratory trials on rabies diagnosis: an overview of results and variation in reference diagnosis techniques (fluorescent antibody test, rabies tissue culture infection test, mouse inoculation test) and molecular biology techniques.

Interlaboratory trials on rabies diagnosis were organised in 2009 and in 2010 by the European Union Reference Laboratory (EURL) for rabies. In 2009, two panels of virus samples were sent to participating laboratories to compare results on reference diagnosis techniques and on RT-PCR. A single panel was sent in 2010 to test FAT (fluorescent antibody test), RTCIT (rabies tissue culture infection test) and RT-PCR techniques. The virus panels included the RABV, EBLV-1, EBLV-2 and ABLV strains. Results revealed that laboratories produced the highest proportion of concordant results using RT-PCR (90.5%) and FAT (87.1%), followed by RTCIT (70.0%) and MIT (35.0%) in 2009 and in FAT (85.0%) and RT-PCR (80.6%) followed by RTCIT (77.3%) in 2010. Errors were only observed in bat strains (i.e. none in the RABV strain) for the RT-PCR or FAT techniques, highlighting the need to improve diagnosis most specifically in such strains. RT-PCR was the technique showing the lowest rate of false negative results in either trial year, while RTCIT and MIT (performed in 2009 only) were the techniques with the lowest proportion of false positive results. Nevertheless, the FAT technique represented a good compromise with both satisfactory sensitivity and specificity, as only a few false positive (1.6% in 2009, 5.8% in 2010) and false negative results (1.6% in both 2009 and 2010) were detected. The analysis of technical questionnaires describing the protocols used by participating laboratories revealed variation in the methods used that may induce inconsistencies in the results. In this study, the number of readers for FAT slide examination was identified as a factor affecting significantly the results of laboratories, suggesting that two independent readers are necessary for routine rabies diagnosis. Our findings highlight the need for all rabies diagnostic laboratories to improve harmonisation of procedures.

Inter-laboratory trial to evaluate the reproducibility of a new ELISA to detect rabies antibodies in vaccinated domestic and wild carnivores.

Validation of new diagnostic assays requires the establishment of their performance characteristics such as diagnostic sensitivity and specificity, precision, repeatability, accuracy and reproducibility. These different stages of validation are described in the recent Standard Operating Procedure for OIE Validation and Certification of Diagnostic Assays. This report describes a reproducibility study of a new ELISA to titrate rabies antibodies in vaccinated wild and domestic carnivores. The study was modelled on the proficiency tests which are annually organised by the Community Reference Institute (Afssa Nancy, France) in the frame of international movements of pets. Analyses demonstrated that the five participants provided satisfactory repeatability estimates (variation coefficients generally below 15% for the 20 coded sera of the panel), and concordant status for all serums. A regression analysis performed on standard curves revealed that two different positive standards used in two dilution ranges were titrated similarly by all participants, and that no significant differences were observed by using these two standards. Titres obtained on a dilution range included in the panel demonstrated that all laboratories were consistent with themselves (significant correlation between experimental and theoretical results), and consistent with other laboratories (significant correlation between results of laboratory under test and mean results of all other laboratories).

Validation and standardization of virus neutralizing test using indirect immunoperoxidase technique for the quantification of antibodies to rabies virus.

A virus neutralizing test using an indirect immunoperoxidase technique (VNT-IIP) for rabies has been developed for the titration of dog and cat serum samples in Japan. The VNT-IIP has the advantage that results obtained can be viewed by the naked eye. The purpose of this study was to validate the VNT-IIP and compare it with one of the international standard methods, the fluorescent antibody virus neutralization test (FAVNT). The VNT-IIP showed satisfactory repeatability, high analytical specificity and good accuracy. Regarding the comparison between the VNT-IIP and the FAVNT, the VNT-IIP showed good agreement (91.9%), high sensitivity (92.8%) as well as specificity (87.0%) and good correlation (r = 0.92). As described above, the validation of the VNT-IIP was satisfactory and the performances of the test proved to be equivalent to those of an international standard method.

Immunolabeling of CD3-positive lymphocytes with a recombinant single-chain antibody/alkaline phosphatase conjugate.

G3(3) is a novel murine monoclonal antibody directed against the CD3 antigen of human T lymphocytes which could be used to analyze lymphoid malignancies. We have produced and characterized a recombinant colorimetric immunoconjugate with the antigen-binding specificity of antibody G3(3). A gene encoding a single-chain antibody variable fragment (scFv) was assembled using the original hybridoma cells as a source of antibody variable heavy (VH) and variable light (VL) chain genes. The chimeric gene was introduced into a prokaryotic expression vector in order to produce a soluble scFv fused to bacterial alkaline phosphatase. DNA sequencing and Western blotting analyses demonstrated the integrity of the soluble immunoconjugate recovered from induced recombinant bacteria. The scFv/AP protein was bifunctional and similar in immunoreactivity to the parent G3(3) antibody. Flow cytometry and immunostaining experiments confirmed that the activity of the scFv/AP protein compares favourably with that of the parent antibody. The scFv/AP conjugate was bound to CD3 antigen at the surface of T cells and was directly detected by its enzymatic activity. Thus this novel fusion protein has potential applications as an immunodiagnostic reagent.