Innovations in vascular access for hemodialysis.

Worldwide, hemodialysis remains the prevalent dialysis modality for more than 2 million patients who require well-functioning vascular access for this procedure. Creation of an arteriovenous fistula for long-term hemodialysis was the first innovation since the Scribner shunt and was followed by the development of an arteriovenous graft and catheter. Bioengineered vessels were developed during the last century, but this field has been energized by recent technology relating to the creation of human vessels. Novel endovascular techniques for creating an arteriovenous fistula may resolve some of the logistical issues involved in obtaining a timely arteriovenous fistula. Treatment of access stenosis, infection, and thrombosis has remained suboptimal, and innovative technologies are evolving. Many new approaches are now targeting the biological and mechanical aspects of vascular access, such as creation and maturation of arterial and venous anastomoses, development of a biological conduit for outflow, and negotiating the problems of central vein stenosis. Importantly, processes of access care that have long focused on arteriovenous fistulas are now recognizing the new paradigm, providing a complementary niche to arteriovenous grafts and dialysis catheters in the algorithm for individualized access placement. Cumulatively, to the credit of the multidisciplinary team approach, the long overdue focus on the very existential issue of vascular access for hemodialysis is being approached with newfound evidence-based enthusiasm as the vexing challenges related to regulations and reimbursement in hemodialysis persist. Patient choice and experience, often missed and ignored in the challenging management of an end-stage organ failure, need to stay central as we focus on patient-centered care of vascular access.

Avoiding problems in tunneled dialysis catheter placement.

Tunneled dialysis catheters (TDCs) remain the predominant vascular access for initiation of hemodialysis (HD) worldwide. TDCs are also utilized in a significant number of prevalent patients for continuation of dialysis and during the periods of complications related to arteriovenous (AV) accesses. TDC placement is a routine procedure, but can be associated with mechanical and infectious complications related to placement. Imaging guidance with ultrasound and fluoroscopy has made the placement of TDC safer and more successful. Adequate operator training, careful technique, utilization of a checklist, and barrier precautions are essential to avoid problems related to TDC placement.

Current and future distribution of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in WHO Eastern Mediterranean Region.

BACKGROUND: Aedes-borne diseases as dengue, zika, chikungunya and yellow fever are an emerging problem worldwide, being transmitted by Aedes aegypti and Aedes albopictus. Lack of up to date information about the distribution of Aedes species hampers surveillance and control. Global databases have been compiled but these did not capture data in the WHO Eastern Mediterranean Region (EMR), and any models built using these datasets fail to identify highly suitable areas where one or both species may occur. The first objective of this study was therefore to update the existing Ae. aegypti (Linnaeus, 1762) and Ae. albopictus (Skuse, 1895) compendia and the second objective was to generate species distribution models targeted to the EMR. A final objective was to engage the WHO points of contacts within the region to provide feedback and hence validate all model outputs. METHODS: The Ae. aegypti and Ae. albopictus compendia provided by Kraemer et al. (Sci Data 2:150035, 2015; Dryad Digit Repos, 2015) were used as starting points. These datasets were extended with more recent species and disease data. In the next step, these sets were filtered using the Köppen-Geiger classification and the Mahalanobis distance. The occurrence data were supplemented with pseudo-absence data as input to Random Forests. The resulting suitability and maximum risk of establishment maps were combined into hard-classified maps per country for expert validation. RESULTS: The EMR datasets consisted of 1995 presence locations for Ae. aegypti and 2868 presence locations for Ae. albopictus. The resulting suitability maps indicated that there exist areas with high suitability and/or maximum risk of establishment for these disease vectors in contrast with previous model output. Precipitation and host availability, expressed as population density and night-time lights, were the most important variables for Ae. aegypti. Host availability was the most important predictor in case of Ae. albopictus. Internal validation was assessed geographically. External validation showed high agreement between the predicted maps and the experts' extensive knowledge of the terrain. CONCLUSION: Maps of distribution and maximum risk of establishment were created for Ae. aegypti and Ae. albopictus for the WHO EMR. These region-specific maps highlighted data gaps and these gaps will be filled using targeted monitoring and surveillance. This will increase the awareness and preparedness of the different countries for Aedes borne diseases.

Complications of Vascular Access: Superior Vena Cava Syndrome.

Stenosis or occlusion of central veins in hemodialysis patients is common, especially with previous intravascular catheter or device use. Superior vena cava (SVC) obstruction is emerging as a frequent chronic complication of central vein cannulation that not only jeopardizes the availability of vascular access for hemodialysis, but can become a life-threatening emergency. Clinical features of SVC syndrome can be subtle or dramatic, including facial swelling and shortness of breath, which require expeditious attention and intervention. The approach to SVC syndrome involves judicious use of imaging techniques to define the cause and location. Early management with endovascular intervention with angioplasty and stent placement is the usual first choice. The occlusion can often be recanalized using new techniques such as radiofrequency wire and then salvaged with stents, providing prompt resolution of symptoms. Limitations to interventions include requirement of cutting-edge equipment, expertise, expense, and the usually temporary nature of the resolution. Surgery is considered the treatment of last resort for refractory cases. SVC syndrome can be prevented by minimizing catheter and intravascular device use through early recognition of patients with chronic kidney disease, early referral for education about all choices for kidney replacement modalities, and early placement of arteriovenous access prior to the onset of dialysis therapy.

Thrombocytopenia in ESRD patients: epidemiology, mechanisms and interventional nephrology perspective.

A well-functioning vascular access is essential for provision of life-sustaining dialysis treatment in patients with end-stage renal disease. Arteriovenous accesses are preferred form of vascular access. Although significant advances have been made in the field of dialysis access, arteriovenous access dysfunction remains the single most important cause of morbidity in ESRD patients. While thrombosis and stenosis of AV access are more frequently seen, hemorrhage from AV access can be life threatening with or without risk of permanent access loss. Aside from anticoagulation for comorbidities, qualitative and/or quantitative platelet abnormalities are often the predisposing factors. We describe an ESRD patient who developed new onset but severe thrombocytopenia due to metastatic small cell neuroendocrine carcinoma of lung. Given her persistent thrombocytopenia and presence of prolonged bleeding from the cannulation sites, a right internal jugular tunneled dialysis catheter was placed for continuation of maintenance dialysis. This review discusses the definition of thrombocytopenia, mechanisms of thrombocytopenia in patients with ESRD and with a special focus on implications of thrombocytopenia on dialysis access interventions. The review underscores the need for consensus with regard to cannulating AV access as well as guidelines specific to dialysis access-related endovascular intervention in the setting of thrombocytopenia and other coagulation abnormalities.

The role of stents in hemodialysis vascular access.

Vascular access is the Achilles' heel of dialysis therapy among patient with end stage kidney disease. The development of neointimal hyperplasia and subsequent stenosis is common in vascular access and is associated with significant morbidity. Percutaneous transluminal angioplasty using balloon inflation was the standard therapy of these lesions. However, the balloon-based approaches were associated with poor vascular access patency rate necessitating new inventions. It is within this context that different types of stents were developed in order to improve the overall dialysis vascular access functionality. In this article, we review the available literature regarding the use of stents in treating dialysis vascular access stenotic lesions. Further, we review the major clinical trials of stent use in different anatomic locations and in different clinical scenarios.

Aedes albopictus in Lebanon, a potential risk of arboviruses outbreak.

BACKGROUND: The mosquito Aedes albopictus is undergoing a worldwide expansion with potential consequences on transmission of various arboviruses. This species has been first detected in Lebanon in 2003. METHODS: We performed a phylogenetic study of Lebanese specimens and assessed their host preference by detecting human, cat, dog and chicken immunoglobulins in mosquito blood-meals. Their capacity to transmit arboviruses was investigated by providing infectious blood-meals using an artificial feeding system followed by detection of viral particles in mosquito saliva. RESULTS: Our results suggest that Lebanese strains are part of the recent wave of Ae. albopictus expansion and are related to some European, African and North American strains. They exhibited a host preference towards humans and an important capacity to transmit arboviruses. Indeed, we showed that Ae. albopictus was able to transmit chikungunya (CHIKV), dengue (DENV) and West-Nile (WNV) viruses. At day 10 after an infectious blood-meal at a titer of 108 MID50/ml, 30% of mosquitoes delivered an average of 515 ± 781 viral particles of CHIKV in saliva collected using a forced salivation technique and 55% with an average of 245 ± 304 viral particles when infected with WNV. Whereas DENV was not found in saliva at day 10 post-infection (pi), an average of 174 ± 455 viral particles was detected in 38.1% of mosquitoes tested at day 21 after an infectious blood-meal at a higher titer of 109 MID50/ml. CONCLUSION: These observations suggest that Ae. albopictus around Beirut is a potential vector of the three tested arboviruses.

The tiger mosquito in Lebanon two decades after its introduction: A growing health concern.

The tiger mosquito was introduced to the Eastern region of the Mediterranean basin more than twenty years ago. In Lebanon, it was first observed in 2002 in a limited number of locations mainly from the coastal area of the country. In the absence of national entomological control program, this invasive mosquito became an established species and is now considered in many localities, a source of nuisance because of its human biting behavior. Several entomological surveys were conducted to monitor the geographic spread and the seasonal dynamics of Aedes albopictus by collecting adult stages and by monitoring oviposition activity. Moreover, its susceptibility to the common groups of insecticides was assessed using WHO standard bioassays. Previous vector competence studies revealed that local strains were able to transmit Chikungunya and Dengue viruses. Due to the increased risk of Zika virus introduction in the country, we determined the competence of local populations to transmit this virus. Mapping results showed that Ae. albopictus is mainly spread in the relatively humid western versant of the Mount Lebanon chain reaching 1000m altitude, while it is absent from arid and semi-arid inland areas. Besides, this mosquito is active during 32 weeks from spring till the end of autumn. Local strains of the tiger mosquito are susceptible to pyrethroids and carbamates but resistant to organophosphates and organochlorines. They showed ability to transmit Zika virus; however, only 9% of females were capable to excrete the virus in their saliva at day 28 post infection. Current and previous observations highlight the need to establish a surveillance system in order to control this mosquito and monitor the potential introduction of related diseases.

Assessment of expertise in morphological identification of mosquito species (Diptera, Culicidae) using photomicrographs.

Accurate identification of insect species is an indispensable and challenging requirement for every entomologist, particularly if the species is involved in disease outbreaks. The European MediLabSecure project designed an identification (ID) exercise available to any willing participant with the aim of assessing and improving knowledge in mosquito taxonomy. The exercise was based on high-definition photomicrographs of mosquitoes (26 adult females and 12 larvae) collected from the western Palaearctic. Sixty-five responses from Europe, North Africa and the Middle East were usable. The study demonstrated that the responders were better at identifying females (82% correct responses) than larvae (63%). When the responders reported that they were sure of the accuracy of their ID, the success rate of ID increased (92% for females and 88% for larvae). The top three tools used for ID were MosKeyTool (72% of responders), the ID key following Becker et al. [2010. Mosquitoes and their control, 2nd edn. Berlin: Springer] (38%), and the CD-ROM of Schaffner et al. [2001. Les moustiques d'Europe: logiciel d'identification et d'enseignement - The mosquitoes of Europe: an identification and training programme. Montpellier: IRD; EID] (32%), while other tools were used by less than 10% of responders. Responders reporting the identification of mosquitoes using the MosKeyTool were significantly better (80% correct responses) than non-MosKeyTool users (69%). Most responders (63%) used more than one ID tool. The feedback from responders in this study was positive, with the exercise being perceived as halfway between educational training and a fun quiz. It raised the importance of further expanding training in mosquito ID for better preparedness of mosquito surveillance and control programmes.

Title: Évaluation de l'expertise en identification morphologique des espèces de moustiques (Diptera, Culicidae) à l'aide de photomicrographies. Abstract: L'identification précise des espèces d'insectes est une exigence indispensable et difficile pour tout entomologiste, en particulier si l'espèce est impliquée dans des épidémies. Le projet européen MediLabSecure a conçu un exercice d'identification (ID) accessible à tout participant volontaire dans le but d'évaluer et d'améliorer les connaissances en taxonomie des moustiques. L'exercice était basé sur des photomicrographies haute définition de moustiques (26 femelles adultes et 12 larves) prélevées dans le Paléarctique occidental. Soixante-cinq réponses d'Europe, d'Afrique du Nord et du Moyen-Orient ont été utilisables. L'étude a démontré que les répondants étaient meilleurs pour identifier les femelles (82 % de réponses correctes) que les larves (63 %). Lorsque les répondants ont déclaré être sûrs de l'exactitude de leur ID, le taux de réussite de l'identification était meilleur (92 % pour les femelles et 88 % pour les larves). Les trois principaux outils utilisés pour les ID étaient MosKeyTool (72 % des répondants), la clé d'identification du livre de Becker et al. (38%) et le CD-ROM de Schaffner et al. (32 %), tandis que d'autres outils étaient utilisés par moins de 10 % des répondants. Les répondants déclarant identifier des moustiques à l'aide de MosKeyTool étaient significativement meilleurs (80 % de réponses correctes) que les non-utilisateurs de MosKeyTool (69 %). La plupart des répondants (63 %) ont utilisé plus d'un outil d'identification. Les commentaires des répondants de cette étude ont été positifs, l'exercice étant perçu comme à mi-chemin entre une formation pédagogique et un quiz amusant. Il a souligné l'importance d'étendre la formation complémentaire à l'identification des moustiques pour une meilleure préparation des programmes de surveillance et de contrôle des moustiques.

Essentials of Vascular Access for Home Hemodialysis.

Hemodialysis (HD) at home has gained increasing popularity in recent years because of regulatory and financial issues. Creation and maintenance of a well-functioning, cannulatable vascular access is essential for performance of home HD (HHD). A vascular access team-based approach to creation, maintenance, and troubleshooting of vascular access can facilitate removing barriers to cannulation at home related to fear of pain and bleeding associated with large bore needles. Frequent cannulation of HD access is associated with more frequent access complications, especially infections. Thus, proper cannulation of arteriovenous access requires careful training of rope ladder and buttonhole techniques to avoid infectious and traumatic complications that can lead to dire consequences. Development of better methods of creating buttonholes and single needles for dialysis can facilitate HHD. A culture of self-cannulation at dialysis centers can also promote HHD.

Evidence of West Nile Virus Circulation in Lebanon.

West Nile virus (WNV) has never been reported from Lebanon. Yet, this country is located on the flyway of migratory birds in the Middle East region. Serological screening was conducted to assess the potential circulation of this virus. Human, horse, and chicken sera were collected from the Bekaa and North districts. Specific IgG and IgY were first screened by ELISA. Then, positive samples were confirmed by plaque reduction neutralization test (PRNT). Besides this, adult mosquitoes were collected and tested for the presence of WNV RNA using conventional RT-PCR. Sera screening revealed a seroprevalence rate reaching 1.86% among humans and 2.47% among horses. Cross-reactions revealed by ELISA suggested the circulation of flaviviruses other than WNV. None of the tested mosquitoes was positive for WNV. The observed results constitute strong evidence of local exposure of the Lebanese population to this virus and the first report of equine WNV in Lebanon.

Dipeptidyl peptidase III as a DNA marker to investigate epidemiology and taxonomy of Old World Leishmania species.

BACKGROUND: Dipeptidyl peptidase III (DPPIII) member of M49 peptidase family is a zinc-dependent metallopeptidase that cleaves dipeptides sequentially from the N-terminus of its substrates. In Leishmania, DPPIII, was reported with other peptidases to play a significant role in parasites' growth and survival. In a previous study, we used a coding sequence annotated as DPPIII to develop and evaluate a PCR assay that is specific to dermotropic Old World (OW) Leishmania species. Thus, our objective was to further assess use of this gene for Leishmania species identification and for phylogeny, and thus for diagnostic and molecular epidemiology studies of Old World Leishmania species. METHODOLOGY: Orthologous DDPIII genes were searched in all Leishmania genomes and aligned to design PCR primers and identify relevant restriction enzymes. A PCR assays was developed and seventy-two Leishmania fragment sequences were analyzed using MEGA X genetics software to infer evolution and phylogenetic relationships of studied species and strains. A PCR-RFLP scheme was also designed and tested on 58 OW Leishmania strains belonging to 8 Leishmania species and evaluated on 75 human clinical skin samples. FINDINGS: Sequence analysis showed 478 variable sites (302 being parsimony informative). Test of natural selection (dN-dS) (-0.164, SE = 0.013) inferred a negative selection, characteristic of essential genes, corroborating the DPPIII importance for parasite survival. Inter- and intra-specific genetic diversity was used to develop universal amplification of a 662bp fragment. Sequence analyses and phylogenies confirmed occurrence of 6 clusters congruent to L. major, L. tropica, L. aethiopica, L. arabica, L. turanica, L. tarentolae species, and one to the L. infantum and L. donovani species complex. A PCR-RFLP algorithm for Leishmania species identification was designed using double digestions with HaeIII and KpnI and with SacI and PvuII endonucleases. Overall, this PCR-RFLP yielded distinct profiles for each of the species L. major, L. tropica, L. aethiopica, L. arabica and L. turanica and the L. (Sauroleishmania) L. tarentolae. The species L. donovani, and L. infantum shared the same profile except for strains of Indian origin. When tested on clinical samples, the DPPIII PCR showed sensitivities of 82.22% when compared to direct examination and was able to identify 84.78% of the positive samples. CONCLUSION: The study demonstrates that DPPIII gene is suitable to detect and identify Leishmania species and to complement other molecular methods for leishmaniases diagnosis and epidemiology. Thus, it can contribute to evidence-based disease control and surveillance.

Iatrogenic graft to vein fistula (GVF) formation associated with synthetic arteriovenous grafts.

The prevalence of fistulous connection between arteriovenous graft (AVG) and an adjacent vein resulting in graft-vein fistula (GVF) formation is not established. AVG venous outflow stenosis along with repeated and traumatic cannulation is likely major contributing factor of this complication. Detection and resolution of venous outflow stenosis may be the only needed intervention. We report a series of eight cases with GVF formation between AVG and adjacent veins. Awareness of this complication and intervention to relieve stenotic lesions may result in improved AVG survival.

Vessel Preservation in Chronic Kidney Disease.

Chronic kidney disease (CKD) is a major noncommunicable disorder and has become the 9th leading cause of death in the United States. Most patients with CKD in the United States choose hemodialysis as their treatment of choice. A functioning arteriovenous access is essential to reduce dependence on central venous catheters. An arteriovenous fistula (AVF), though the preferred access, has a major limitation with a high primary maturation failure rate. A functioning AVF requires well-preserved vessels, both arteries and veins, along with an acceptable cardiac pump function. Vessel preservation is crucial from a surgeon's perspective to create an AVF but is also relevant for maturation. More recently, concerns regarding the sequelae of transradial approach for percutaneous cardiac interventions have been raised. Educating and empowering the patient is the first step, but equally important is to educate all caregivers involved in providing care to a patient with advanced CKD. The current review evaluates the strategies used to preserve peripheral veins, central veins, and peripheral arteries.

Fertility and endocrine effects of intra-abdominally misplaced intrauterine system for more than 2 years: a case report and review of the literature.

This case report shows with documented evidence that a misplaced Mirena intrauterine system in the abdominal cavity had an endocrine and contraceptive effect causing amenorrhea and infertility for 2 years and 5 months. This had been proved by a negative hysteroscopy in November 2004 and an abdominal X-ray showing the device which was done in May 2007. Intraabdominal misplacement of the LNG-IUS has been reported in the literature with variable consequences and effects. In this case report, we reviewed the literature and assessed the fertility and endocrine consequences.

Towards harmonisation of entomological surveillance in the Mediterranean area.

BACKGROUND: The Mediterranean Basin is historically a hotspot for trade, transport, and migration. As a result, countries surrounding the Mediterranean Sea share common public health threats. Among them are vector-borne diseases, and in particular, mosquito-borne viral diseases are prime candidates as (re)emerging diseases and are likely to spread across the area. Improving preparedness and response capacities to these threats at the regional level is therefore a major issue. The implementation of entomological surveillance is, in particular, of utmost importance. Guidance in designing entomological surveillance systems is critical, and these systems may pursue different specific objectives depending on the disease. The purpose of the proposed review is to draw up guidelines for designing effective and sustainable entomological surveillance systems in order to improve preparedness and response. However, we make it clear that there is no universal surveillance system, so the thinking behind harmonisation is to define evidence-based standards in order to promote best practises, identify the most appropriate surveillance activities, and optimise the use of resources. Such guidance is aimed at policymakers and diverse stakeholders and is intended to be used as a framework for the implementation of entomological surveillance programmes. It will also be useful to collaborate and share information with health professionals involved in other areas of disease surveillance. Medical entomologists and vector control professionals will be able to refer to this report to advocate for tailored entomological surveillance strategies. The main threats targeted in this review are the vectors of dengue virus, chikungunya virus, Zika virus, West Nile virus, and Rift Valley fever virus. The vectors of all these arboviruses are mosquitoes. METHODS: Current knowledge on vector surveillance in the Mediterranean area is reviewed. The analysis was carried out by a collaboration of the medical entomology experts in the region, all of whom belong to the MediLabSecure network, which is currently funded by the European Union and represents an international effort encompassing 19 countries in the Mediterranean and Black Sea region. FINDINGS: Robust surveillance systems are required to address the globalisation of emerging arboviruses. The prevention and management of mosquito-borne viral diseases must be addressed in the prism of a One Health strategy that includes entomological surveillance as an integral part of the policy. Entomological surveillance systems should be designed according to the entomological and epidemiological context and must have well-defined objectives in order to effect a tailored and graduated response. We therefore rely on different scenarios according to different entomological and epidemiological contexts and set out detailed objectives of surveillance. The development of multidisciplinary networks involving both academics and public authorities will provide resources to address these health challenges by promoting good practises in surveillance (identification of surveillance aims, design of surveillance systems, data collection, dissemination of surveillance results, evaluation of surveillance activities) and through the sharing of effective knowledge and information. These networks will also contribute to capacity building and stronger collaborations between sectors at both the local and regional levels. Finally, concrete guidance is offered on the vector of the main arbovirus based on the current situation in the area.

Experimental transmission of West Nile Virus and Rift Valley Fever Virus by Culex pipiens from Lebanon.

West Nile virus (WNV) and Rift Valley fever virus (RVFV) are two emerging arboviruses transmitted by Culex pipiens species that includes two biotypes: pipiens and molestus. In Lebanon, human cases caused by WNV and RVFV have never been reported. However, the introduction of these viruses in the country is likely to occur through the migratory birds and animal trades. In this study, we evaluated the ability of Cx. pipiens, a predominant mosquito species in urban and rural regions in Lebanon, to transmit WNV and RVFV. Culex egg rafts were collected in the West Bekaa district, east of Lebanon and adult females of Cx. pipiens were experimentally infected with WNV and RVFV Clone 13 strain at titers of 1.6×108 and 1.33×107 plaque forming units (PFU)/mL, respectively. We estimated viral infection, dissemination and transmission at 3, 7, 14 and 19 days post infection (dpi). Results showed that infection was higher for WNV than for RVFV from 3 dpi to 19 dpi. Viral dissemination and transmission started from 3 dpi for WNV; and only from 19 dpi for RVFV. Moreover, Cx. pipiens were able to excrete in saliva a higher number of viral particles of WNV (1028 ± 405 PFU/saliva at 19 dpi) than RVFV (42 PFU/saliva at 19 dpi). Cx. pipiens from Lebanon are efficient experimental vectors of WNV and to a lower extent, RVFV. These findings should stimulate local authorities to establish an active entomological surveillance in addition to animal surveys for both viruses in the country.