Castor (Ricinus communis L.) differential cell cycle and metabolism reactivation, germinability, and seedling performance under NaCl and PEG osmoticum: Stress tolerance related to genotype-preestablished superoxide dismutase activity.

Castor (Ricinus communis) is a relevant industrial oilseed feedstock for many industrial applications, being globally mainly cultivated by smallholder farmers in semiarid areas, where abiotic stresses predominate. Therefore, susceptible to generating reactive oxygen species (ROS) and subsequent oxidative stress, compromising cell metabolism upon seed imbibition and germination, seedling and crop establishment, and yield. The present study evaluated the consequences of water restriction by Polyethylene glycol (PEG) and Sodium chloride (NaCl) on cell cycle and metabolism reactivation on germinability, seedling growth, and vigor parameters in 2 commercial castor genotypes (Nordestina and Paraguaçu). PEG water restriction inhibited germination completely at -0.23 MPa or higher, presumably due to reduced oxygen availability. The restrictive effects of NaCl saline stress on germination were observed only from -0.46 MPa onwards, affecting dry mass accumulation and the production of normal seedlings. In general, superoxide dismutase (SOD) activity increased in NaCl -0.23 MPa, whereas its modulation during the onset of imbibition (24h) seemed to depend on its initial levels in dry seeds in a genotype-specific manner, therefore, resulting in the higher stress tolerance of Nordestina compared to Paraguaçu. Overall, results show that Castor germination and seedling development are more sensitive to the restrictive effects of PEG than NaCl at similar osmotic potentials, contributing to a better understanding of the responses to water restriction stresses by different Castor genotypes. Ultimately, SOD may constitute a potential marker for characterizing castor genotypes in stressful situations during germination, early seedling, and crop establishment, and a target for breeding for Castor-improved stress tolerance.

Spatial Distribution of Dengue in a Brazilian Urban Slum Setting: Role of Socioeconomic Gradient in Disease Risk.

BACKGROUND: Few studies of dengue have shown group-level associations between demographic, socioeconomic, or geographic characteristics and the spatial distribution of dengue within small urban areas. This study aimed to examine whether specific characteristics of an urban slum community were associated with the risk of dengue disease. METHODOLOGY/PRINCIPAL FINDINGS: From 01/2009 to 12/2010, we conducted enhanced, community-based surveillance in the only public emergency unit in a slum in Salvador, Brazil to identify acute febrile illness (AFI) patients with laboratory evidence of dengue infection. Patient households were geocoded within census tracts (CTs). Demographic, socioeconomic, and geographical data were obtained from the 2010 national census. Associations between CTs characteristics and the spatial risk of both dengue and non-dengue AFI were assessed by Poisson log-normal and conditional auto-regressive models (CAR). We identified 651 (22.0%) dengue cases among 2,962 AFI patients. Estimated risk of symptomatic dengue was 21.3 and 70.2 cases per 10,000 inhabitants in 2009 and 2010, respectively. All the four dengue serotypes were identified, but DENV2 predominated (DENV1: 8.1%; DENV2: 90.7%; DENV3: 0.4%; DENV4: 0.8%). Multivariable CAR regression analysis showed increased dengue risk in CTs with poorer inhabitants (RR: 1.02 for each percent increase in the frequency of families earning ≤1 times the minimum wage; 95% CI: 1.01-1.04), and decreased risk in CTs located farther from the health unit (RR: 0.87 for each 100 meter increase; 95% CI: 0.80-0.94). The same CTs characteristics were also associated with non-dengue AFI risk. CONCLUSIONS/SIGNIFICANCE: This study highlights the large burden of symptomatic dengue on individuals living in urban slums in Brazil. Lower neighborhood socioeconomic status was independently associated with increased risk of dengue, indicating that within slum communities with high levels of absolute poverty, factors associated with the social gradient influence dengue transmission. In addition, poor geographic access to health services may be a barrier to identifying both dengue and non-dengue AFI cases. Therefore, further spatial studies should account for this potential source of bias.

Accuracy of a dual path platform (DPP) assay for the rapid point-of-care diagnosis of human leptospirosis.

BACKGROUND: Diagnosis of leptospirosis by the gold standard serologic assay, the microscopic agglutination test (MAT), requires paired sera and is not widely available. We developed a rapid assay using immunodominant Leptospira immunoglobulin-like (Lig) proteins in a Dual Path Platform (DPP). This study aimed to evaluate the assay's diagnostic performance in the setting of urban transmission. METHODOLOGY: We determined test sensitivity using 446 acute and convalescent sera from MAT-confirmed case-patients with severe or mild leptospirosis in Brazil. We assessed test specificity using 677 sera from the following groups: healthy residents of a Brazilian slum with endemic transmission, febrile outpatients from the same slum, healthy blood donors, and patients with dengue, hepatitis A, and syphilis. Three operators independently interpreted visual results without knowing specimen status. RESULTS: The overall sensitivity for paired sera was 100% and 73% for severe and mild disease, respectively. In the acute phase, the assay achieved a sensitivity of 85% and 64% for severe and mild leptospirosis, respectively. Within seven days of illness onset, the assay achieved a sensitivity of 77% for severe disease and 60% for mild leptospirosis. Sensitivity of the DPP assay was similar to that for IgM-ELISA and increased with both duration of symptoms (chi-square regression P = 0.002) and agglutinating titer (Spearman ρ = 0.24, P<0.001). Specificity was ≥93% for dengue, hepatitis A, syphilis, febrile outpatients, and blood donors, while it was 86% for healthy slum residents. Inter-operator agreement ranged from very good to excellent (kappa: 0.82-0.94) and test-to-test reproducibility was also high (kappa: 0.89). CONCLUSIONS: The DPP assay performed acceptably well for diagnosis of severe acute clinical leptospirosis and can be easily implemented in hospitals and health posts where leptospirosis is a major public health problem. However, test accuracy may need improvement for mild disease and early stage leptospirosis, particularly in regions with high transmission.

Prevalence of Streptococcus pneumoniae serotype 6C among invasive and carriage isolates in metropolitan Salvador, Brazil, from 1996 to 2007.

The newly described Streptococcus pneumoniae serotype 6C accounted for 2.3% (16/709) of meningitis cases and 3.2% (3/95) of nasopharyngeal isolates from healthy individuals in Brazil. The strains were multidrug resistant (18.8%) and genetically diverse. Despite low serotype 6C prevalence, continuous surveillance is necessary to guide vaccine strategies.

Burden of group A streptococcal meningitis in Salvador, Brazil: report of 11 years of population-based surveillance.

BACKGROUND: Over recent decades, a resurgence of invasive group A streptococcal (GAS) infections has been observed; GAS remains a rare cause of pyogenic meningitis. We report herein population-based findings of long-term surveillance for GAS meningitis in Salvador, Brazil, and estimate the overall burden of invasive GAS infections. METHODS: From February 1996 to February 2007 we conducted active surveillance for GAS meningitis in the state reference hospital for infectious diseases in Salvador, Brazil. Data on clinical presentation, laboratory records, and outcome were collected through interviews and chart review. GAS isolates were evaluated for antimicrobial susceptibility and emm type. RESULTS: We identified 20 cases of GAS meningitis, which accounted for 0.9% of all culture-proven bacterial meningitis in the study period. The mean annual incidence of GAS meningitis was 0.03 cases per 100,000 population in metropolitan Salvador and peaked in children <1 year of age (0.67 cases per 100,000 population). Among 17 cases with clinical information available, 41% required intensive care unit support and 25% died. Tested isolates were susceptible to penicillin and exhibited large emm type diversity. Based on the incidence of GAS meningitis, we estimate that the annual incidence of GAS infection is 3 cases per 100,000 population in metropolitan Salvador. CONCLUSIONS: Although rare, GAS is a life-threatening cause of bacterial meningitis. Knowledge of the incidence and emm type variability of the disease is necessary for planning immunization strategies.