Lúcio M. Barbosa

Schistosoma mansoni population structure and persistence after praziquantel treatment in two villages of Bahia, Brazil

Praziquantel has been used to treat schistosome infections since 1979 and currently is the only chemotherapeutic agent in production for this purpose, raising concerns about the potential for the emergence of drug resistance. In practice, 10-20% of infected patients will continue to excrete eggs after treatment. It is not understood to what degree this represents selection of a resistant population or incomplete elimination due to the presence of immature worms at the time of treatment. We used a population genetics approach to test whether or not persistent Schistosomamansoni parasites were drawn from the same population as susceptible parasites. In this study, stool samples were collected from 96% of individuals in two small Brazilian communities (populations 482 and 367) and examined for S.mansoni eggs. The combined prevalence of S.mansoni infections in the villages was 41%. Total egg DNA was extracted from each sample and was genotyped at 15 microsatellite markers. Day-to-day variation of the infrapopulation from an individual human host was low (median differentiation using Josts D=0.010), so that a single stool was representative of the genotypes present in stool eggs, at least in the short term. Average pairwise analysis of D among all pre-treatment infrapopulations suggested moderate differentiation (mean D=0.082 and 0.122 for the two villages), whereas the pre-treatment component population differentiation between the two communities was 0.047. The differentiation of the component population remaining after treatment from the fully susceptible component population was low (mean D=0.007 and 0.020 for the two villages), suggesting that the persistent parasites were not selected by praziquantel treatment. We will continue to follow these communities for evidence of selection or changes in population structure.

NK and NKT cell dynamics after rituximab therapy for systemic lupus erythematosus and rheumatoid arthritis

Biomarkers of clinical response to rituximab (RTX) therapy and early predictors of outcome are still under investigation. We report a flow cytometric immunophenotyping analysis from peripheral blood leukocyte subpopulations of two patients with systemic lupus erythematosus (SLE) associated thrombocytopenia and one patient with rheumatoid arthritis (RA), before and after 6 weeks of treatment with RTX. Our results show a reduced population of CD19+ expressing cells (B cells) after RTX treatment in all three patients. Increased frequency of peripheral regulatory CD4+CD25high T cell subset and the CD3−CD16−CD56bright NK cell subset after RTX therapy were also observed in all patients, the latter being more pronounced in the SLE patient with sustained clinical response. In addition, an increased population of NKT cell subsets was observed in the patients with clinical response. This is the first evaluation of NK and NKT cells as biomarkers of clinical response after rituximab therapy in rheumatic diseases.

Anti-C1q Antibodies: Association With Nephritis and Disease Activity in Systemic Lupus Erythematosus

Background: Anti‐C1q antibodies have been described in systemic lupus erythematosus (SLE) as well as in other connective tissue diseases. They have been considered as a marker for disease activity and presence of nephritis.

Repeated praziquantel treatments remodel the genetic and spatial landscape of schistosomiasis risk and transmission

Repeated treatments with praziquantel reduce schistosomiasis prevalence and morbidity, but transmission persists and populations often recover within a few years. To identify factors associated with persistence, we surveyed and treated all identified Schistosoma mansoni infections in two rural Brazilian communities (Jenipapo and Volta do Rio) in 2009, 2012 and 2013. Eggs were collected from all infected individuals and genotyped with 11 microsatellite markers to evaluate parasite differentiation and diversity. After successive rounds of community-wide treatment, prevalence decreased from 45% to 24% then 16%. Intensity of infection decreased by 57% over this period, and the number of eggs transmitted to the environment decreased by 92%. During all time periods the majority of eggs were excreted by those >15years of age. The incidence was 23% in 2012 and 15% in 2013, consistent with a decrease in transmission. There was little immigration or gene flow over a distance of 6km. On reinfection, infrapopulations were moderately differentiated indicating that pretreatment multilocus genotypes were not fully reacquired. The effective population size responded to census population decline more rapidly than differentiation. Reinfection was concentrated in the downstream portion of Jenipapo, consistent with the observed increased human fecal contamination. At this scale and in this area S. mansoni infections exist on a fragmented landscape with a highly focal pattern of transmission that may facilitate future elimination.

Genetic Population Structure of Cercariae from an Urban Foci of Schistosoma mansoni, Brazil

Rapid urbanization in Brazil has meant that many persons from rural areas where Schistosoma mansoni is endemic have migrated to cities. Discovery of a focus of active transmission in the city of Salvador prompted a citywide survey for active and potential transmission sites. Cercariae shed from infected snails collected from four locations were used to determine how these samples were related and if they were representative of the parasite population infecting humans. Each cercarial collection was greatly differentiated from the others, and diversity was significantly lower when compared with eggs from natural human infections in one site. Egg samples collected 7 years apart in one neighborhood showed little differentiation (Josts D = 0.01-0.03). Given the clonal nature of parasite reproduction in the snail host and the short-term acquisition of parasites, cercariae from collections at one time point are unlikely to be representative of the diversity in the human population.

Pesquisa de anticorpos antinucleossoma em lúpus eritematoso sistêmico

OBJECTIVE: to determine the frequency of antinucleosome (AN) antibodies in systemic lupus erythematosus (SLE) and their association with disease activity. METHODS: cross-sectional study to evaluate patients with diagnosis of SLE based on the American College of Rheumatology criteria. SLEDAI score was used as a disease activity index. AN antibodies were tested by ELISA (INOVA Diagnostics Inc). Systemic sclerosis (SSc) and myositis patients were also studied to determine the diagnostic performance of the ELISA system. RESULTS: a total of 82 SLE patients, 81 female, mean age 35 ± 11.7 years were included in the study. AN antibodies were positive in 48 SLE samples (58.5%), three with myositis (21.4%) and two with SSc (14.2%), determining a sensitivity and specificity of AN antibodies for the diagnosis of SLE of 58.5% and 82.14%, respectively. Utilizing a cut off of 40 U, test was positive in 45 SLE samples (53.65%), two with myositis (13.33%) and one with SSc (6.66%), determining a sensitivity and specificity of AN antibodies for the diagnosis of SLE of 53.65% and 90%, respectively. There were no correlation between AN antibodies and SLEDAI scores. On the other hand, it was observed a positive correlation between anti-DNA antibodies and disease activity (r = 0.42; p < 0.005). CONCLUSIONS: in the present study it was demonstrated a high specificity and moderate sensitivity of AN antibodies for the diagnosis of SLE. However, the lack of association with disease activity suggests that it has limited value in rheumatologic practice.

Synthesis, characterization and applications of maghemite beads functionalized with rabbit antibodies

Magnetic nanoparticles (NPs) have attracted great attention owing to their applications in the biomedical field. In the present work, maghemite (γFe2O3) NPs of 6.5 nm were prepared using a sonochemical method and used to prepare magnetic beads through silanization with 3-aminopropyltrimethoxysilane (APTS). Subsequently, amino groups in the resulting APTS-γFe2O3 beads were converted to carboxylic acid (CARB-γFe2O3) through the succinic anhydride reaction, as confirmed by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and dynamic light scattering (DLS) measurements. The size of these beads was measured as 12 nm and their hydrodynamic diameter as 490 nm, using TEM analysis and DLS, respectively. The CARB-γFe2O3 beads were further functionalized by immobilizing rabbit antibodies on their surfaces; the immobilization was confirmed by flow cytometry and ionic strength. The samples were further characterized by Mössbauer spectroscopy and DC magnetization measurements. Studies on magnetic relaxivities showed that magnetic beads present great potential for application in MR imaging.

The effect of sample size on estimates of genetic differentiation and effective population size for Schistosoma mansoni populations

Eradication or local extinction of the human parasite Schistosoma mansoni is a goal for many control programs. Population genetic analyses are helping to evaluate and guide these efforts, yet what to sample, how to sample and how densely to sample is not well established. We determined the S. mansoni allele frequency profile of nearly all infected inhabitants in two small Brazilian communities and created sub-samples representing 5-50% of all detected human infections (infrapopulations). Samples were selected at random with replacement, and each size class was replicated 100 times. Mean pairwise differentiation for all infrapopulations (Di) and the variance effective population size (Ne) were calculated for each sample. Prior to community-wide treatment, the true mean Di was moderate (0.095-0.123) and Ne large (>30,000). Most samples of <50% of those infected produced estimates outside of 5% of the true value. For estimates within 10%, sample sizes of >15% of all infrapopulations were required. At the 3 year follow-up after treatment, the Di increased and Ne was reduced by >15 fold. At this time sampling of >30-45% was needed to achieve the same accuracy. Following a second treatment and 4 years from baseline, the Di further increased and Ne decreased with little change in the sampling effort required. Extensive sampling is required for accurate estimates of these important population parameters. Characteristics such as population census size, infection prevalence, the communitys treatment history and the degree of infrapopulation differentiation should be taken into account. The intensity of infection was weakly correlated with the ability of a single infrapopulation to represent the component population (Dic), indicating a tendency toward random acquisition of parasite genotypes. This also suggests that targeted sampling from those most heavily infected will better represent the genetic diversity of the whole community than a random sample of infrapopulations.

Alcohol preparation compared to traditional surgical hand antisepsis: acceptance by surgical team at a private hospital in Brazil

Traditional surgical hand scrubbing (TSHS) has been replaced by alcohol-based formulation (ABF) in many countries due to antimicrobial efficacy, easy application, lower skin damage, time saver and no recontamination risk by rinsing hands with water [1]. In Brazil, chlorhexidine (CHG) and povidone-iodine (PVPI) are used for TSHS.