Loss of NK Stimulatory Capacity by Plasmacytoid and Monocyte-Derived DC but Not Myeloid DC in HIV-1 Infected Patients

Dendritic cells (DC) are potent inducers of natural killer (NK) cells. There are two distinct populations in blood, myeloid (mDC) and plasmacytoid (pDC) but they can also be generated In vitro from monocytes (mdDC). Although it is established that blood DC are lost in HIV-1 infection, the full impact of HIV-1 infection on DC-NK cell interactions remains elusive. We thus investigated the ability of pDC, mDC, and mdDC from viremic and anti-retroviral therapy-treated aviremic HIV-1+ patients to stimulate various NK cell functions. Stimulated pDC and mdDC from HIV-1+ patients showed reduced secretion of IFN-α and IL-12p70 respectively and their capacity to stimulate expression of CD25 and CD69, and IFN-γ secretion in NK cells was also reduced. pDC activation of NK cell degranulation in response to a tumour cell line was severely reduced in HIV-1+ patients but the ability of mDC to activate NK cells was not affected by HIV-1 infection, with the exception of HLA-DR induction. No differences were observed between viremic and aviremic patients indicating that anti-retroviral therapy had minimal effect on restoration on pDC and mdDC-mediated activation of NK cells. Results from this study provide further insight into HIV-1 mediated suppression of innate immune functions

IL-1β, IL-6, and RANTES as Biomarkers of Chikungunya Severity

Little is known about the immunopathogenesis of Chikungunya virus. Circulating levels of immune mediators and growth factors were analyzed from patients infected during the first Singaporean Chikungunya fever outbreak in early 2008 to establish biomarkers associated with infection and/or disease severity.Adult patients with laboratory-confirmed Chikungunya fever infection, who were referred to the Communicable Disease Centre/Tan Tock Seng Hospital during the period from January to February 2008, were included in this retrospective study. Plasma fractions were analyzed using a multiplex-microbead immunoassay. Among the patients, the most common clinical features were fever (100%), arthralgia (90%), rash (50%) and conjunctivitis (40%). Profiles of 30 cytokines, chemokines, and growth factors were able to discriminate the clinical forms of Chikungunya from healthy controls, with patients classified as non-severe and severe disease. Levels of 8 plasma cytokines and 4 growth factors were significantly elevated. Statistical analysis showed that an increase in IL-1beta, IL-6 and a decrease in RANTES were associated with disease severity.This is the first comprehensive report on the production of cytokines, chemokines, and growth factors during acute Chikungunya virus infection. Using these biomarkers, we were able to distinguish between mild disease and more severe forms of Chikungunya fever, thus enabling the identification of patients with poor prognosis and monitoring of the disease

New materials and devices for preventing catheter-related infections

Catheters are the leading source of bloodstream infections for patients in the intensive care unit (ICU). Comprehensive unit-based programs have proven to be effective in decreasing catheter-related bloodstream infections (CR-BSIs). ICU rates of CR-BSI higher than 2 per 1,000 catheter-days are no longer acceptable. The locally adapted list of preventive measures should include skin antisepsis with an alcoholic preparation, maximal barrier precautions, a strict catheter maintenance policy, and removal of unnecessary catheters. The development of new technologies capable of further decreasing the now low CR-BSI rate is a major challenge. Recently, new materials that decrease the risk of skin-to-vein bacterial migration, such as new antiseptic dressings, were extensively tested. Antimicrobial-coated catheters can prevent CR-BSI but have a theoretical risk of selecting resistant bacteria. An antimicrobial or antiseptic lock may prevent bacterial migration from the hub to the bloodstream. This review discusses the available knowledge about these new technologies

Hummingbird diversity, food niche characters, and assemblage composition along a latitudinal precipitation gradient in the Bolivian lowlands

As for many other taxa, hummingbird diversity declines away from the equator, but the causes for this decline are still disputed and might involve, among others, climatic factors or the availability of food resources. Because hummingbirds are one of the classical examples for plant–animal coevolution, it has been proposed that the diversity of hummingbird assemblages might depend on the diversity of food plants available. We tested this hypothesis by studying the hummingbird assemblages and their food plants for 1 year at six sites along a 660-km-long transect in Bolivian lowland forests extending from the southernmost Amazonian rain forests to dry Chaco forests. Hummingbird diversity was higher in the northern three sites as compared to the southern ones, with an abrupt decline in species numbers and a corresponding change in taxonomic composition at the boundary from evergreen to drought deciduous forests. Hummingbird diversity and abundance were only weakly correlated to climatic factors or to the diversity of humming-visited flowers, but strongly to the seasonal abundance of flowers. The overlap in nectar diet between hummingbird species depended on the number of plant species: when numerous species were available, the hummingbirds segregated by feeding preferences, but when few flowers were available, all hummingbirds fed on the same plants. We conclude that the local diversity of hummingbird species is not primarily determined by the diversity of food plants, but rather by the abundance of flowers available at any given point in time