Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity.     

Yeast populations associated with the artisanal cheese produced in the region of Serra da Canastra, Brazil

The aim of this work was to describe the yeast populations present during the manufacturing of Minas cheese of the region of Serra da Canastra, Minas Gerais state, Brazil. Canastra cheese is produced from raw cow’s milk at the farmhouse level using artisanal procedures and natural whey cultures as starters. Samples from 10 farms were studied, and they included: raw milk, natural starter, cheese curd before salting and cheese after 5 days of ripening. The most frequent yeasts in whey, curd and cheese were Debaryomyces hansenii, Kluyveromyces lactis, Kodamaea ohmeri and Torulaspora delbrueckii. Many yeast isolates were able to produce proteases, lipases and β-galactosidades. Production of these enzymes by yeasts in the cheese would contribute to the development of the characteristic flavor and smell during the ripening process.     

Synthesis and characterization of cross-linked malonylchitosan microspheres for controlled release of acyclovir

The purpose of the present study was to obtain a polymeric system for delayed release of the drug acyclovir (ACV), which can be used for treatment of Herpes simplex and Varicella Zoster. The gelled chitosan (GCT) microspheres were obtained by coacervation-phase separation. They were treated with malonic acid to obtain malonylchitosan (MLCT) microspheres, which were characterized by, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (¹³C NMR), elemental analysis (CHN), thermogravimetric analysis (TG/DTG) and scanning electron microscopy (SEM). The drug was encapsulated in MLCT microspheres by a contact adsorption technique, and the final formulation (MLCT-ACV), was analyzed for loading efficiency, degree of swelling and in vitro release profiles. The results obtained support the N-substitution of malonyl groups in the MLCT microspheres. The loading efficiency increased with impregnation time and a major amount of drug was encapsulated after 24 h. The swelling rate was higher in acid pH. The median release time was 5.5 h in pH 1.2 and 6.8. The mechanism involved in release was non-Fickian (0.43 < n < 0.85, n = 0.8474) and Super Case II kinetics (n > 1, n = 1.0491) at pH 1.2 and 6.8, respectively.     

Heterogeneity in response to serological exposure markers of recent Plasmodium vivax infections in contrasting epidemiological contexts

BackgroundAntibody responses as serological markers of Plasmodium vivax infection have been shown to correlate with exposure, but little is known about the other factors that affect antibody responses in naturally infected people from endemic settings. To address this question, we studied IgG responses to novel serological exposure markers (SEMs) of P. vivax in three settings with different transmission intensity.MethodologyWe validated a panel of 34 SEMs in a Peruvian cohort with up to three years’ longitudinal follow-up using a multiplex platform and compared results to data from cohorts in Thailand and Brazil. Linear regression models were used to characterize the association between antibody responses and age, the number of detected blood-stage infections during follow-up, and time since previous infection. Receiver Operating Characteristic (ROC) analysis was used to test the performance of SEMs to identify P. vivax infections in the previous 9 months.Principal findingsAntibody titers were associated with age, the number of blood-stage infections, and time since previous P. vivax infection in all three study sites. The association between antibody titers and time since previous P. vivax infection was stronger in the low transmission settings of Thailand and Brazil compared to the higher transmission setting in Peru. Of the SEMs tested, antibody responses to RBP2b had the highest performance for classifying recent exposure in all sites, with area under the ROC curve (AUC) = 0.83 in Thailand, AUC = 0.79 in Brazil, and AUC = 0.68 in Peru.ConclusionsIn low transmission settings, P. vivax SEMs can accurately identify individuals with recent blood-stage infections. In higher transmission settings, the accuracy of this approach diminishes substantially. We recommend using P. vivax SEMs in low transmission settings pursuing malaria elimination, but they are likely to be less effective in high transmission settings focused on malaria control.     

Phytoplankton nyctemeral variation at a tropical river estuary (Itamaracá-Pernambuco-Brazil).

The Botafogo estuary is of socio-economical importance for Pernambuco State. It is located at the north of Santa Cruz Channel, Itamaracá, Pernambuco, Brazil (07 degrees 42' 50 "S and 34 degrees 52' 10" W). There is a critical need to understand its functioning because of the rate at which this area is being converted to land uses. The phytoplankton dynamics was studied to enhance the knowledge of and verify the possible changes which have occurred in this ecosystem. Sampling was carried out with a plankton net 65 micrometers mesh size for qualitative data, and a Van Dorn bottle for quantitative data. Concurrent hydrological and chlorophyll-a data were collected. Samplings were made in one fixed station in July 1996 (rainy season) and December 1996 (dry season), at 3-hour intervals during 24 hours. Eighty-seven specific and infra-specific taxa were identified from net plankton samples. Diatoms were most frequent, mainly Coscinodiscus centralis and Odontella regia in the rainy and dry seasons, respectively. Phytoplankton density varied from 205,000 to 1,210,000 cell.L-1 in the dry season, and from 230,000 to 2,510,000 cell.L-1 in the rainy season, indicating eutrophic conditions. Most numerically abundant were the diatoms Cyclotella meneghiniana and Cylindrotheca closterium and the phytoflagellates. The ecosystem is polluted, and deleterious effects are minimized by the marine influence which allows periodic water renewal.     

LH response (in vivo and in vitro) to an LHRH agonist administered to domestic male cats

We investigated plasma luteinizing hormone (LH) concentration in domestic male cats challenged with Luteinizing Hormone Releasing Hormone Analog (LHRH-A) [des Gly 10, (DTrp6)-LHRH ethylamide] that mediates the function of the hypothalamic-pituitary-gonadal axis (HPG). Plasma LH concentrations in cats treated daily with LHRH (10 microg/100 microl/kg/day, subcutaneously-s.c.) for 19 days (LHRH group) and in controls treated with saline (NaCl-0.9%, same volume-SAL group) were chronically studied. LHRH administration (s.c.) for 15 days induced a significant fall (P < 0.05) in plasma LH concentrations during the chronic study. After the 15th day of treatment the groups were divided once more into animals treated with LHRH (10 microg/100 microl/kg) or saline (i.v.), and a time course study (300 min) was performed (acute study). Next, four groups of cats were compared in an acute study involving the s.c./i.v. administration of SAL/SAL, SAL/LHRH, LHRH/SAL, and LHRH/LHRH. The responses of the SAL animals challenged by acute i.v. administration of LHRH (group SAL/LHRH) were significantly higher (P < 0.01) than those of animals treated with LHRH (sc) (group LHRH/LHRH). LH release was also significantly increased in the latter group (P < 0.05), although the effect was short lasting, being recorded only at the first observation (45 min). An in vitro study with the pituitaries was also performed on day 20. Mean (+/-SEM) LH concentrations in the culture medium containing pituitaries with LHRH (10(-7) M) or saline were determined. In vitro analysis of these pituitaries demonstrated a significantly reduced response (P < 0.05) by animals treated sc with LHRH for 19 days. This study represents a source of data for the domestic cat going beyond its own physiology. Serving as a model, this animal provide important information for the study of reproductive physiology in other members of its family (Felidae), almost all of them threatened with extinction.     

Chemical fingerprint,acute oral toxicity and anti-inflammatory activity of the hydroalcoholic extract of leaves from Tocoyena formosa (Cham. & Schlecht.) K. Schum

Inflammation is a protective response of the organism against damaging agents, this process is considered beneficial, however in some situations, this response can be damage when exacerbated effect are present. This claim objective to evaluate the qualitative and quantitative chemical profile, acute toxic and anti-inflammatory effects of the hydroalcoholic extract of leaves from Tocoyena formosa (Cham. & Schlecht.) K. Schum. (HELTF). Quantitative and qualitative phytochemical analysis was performed by HPLC-DAD and colorimetric assay. The topical anti-inflammatory activity was determined in Croton oil-induced ear edema assay and systemic activity was performed in vascular permeability, paw edema induced by carrageenan and dextran. Phytochemical analysis of leaves from HELTF showed presence of tannin, flavonoid, saponins an other that confirmed by HPLC analysis. The extract did not cause significant with LD₅₀ greater than 5000 mg/kg and did not promote significate reduction in topical inflammatory process. However, HELTF demonstrate significant reduction of paw edema induced by carrageenan and dextran. The HELTF (200 mg/kg) reduced the protein/cell migration in the intradermal carrageenan-induced inflammation. Our results demonstrated that the first time the chemical profile and describe the effective action in systemic anti-inflammatory, antiedematogenic activity and low acute toxicity. This activity presents, supporting its traditional use. However, new studies are necessary for the detection and clarification of the possible mechanism of action.     

Long-pollen Movement and Deviation of Random Mating in a Low-density Continuous Population of a Tropical Tree Hymenaea courbaril in the Brazilian Amazon

Mating system and pollen flow are two key elements to understand the genetic structure of tree species. Mating and pollen-dispersal patterns of a low-density population of bat pollinated Hymanea courbaril were examined before logging in a 546-ha plot in the Brazilian Amazon. The multilocus genotypes of nine microsatellite loci were determined for 130 adult-trees and 367 seeds collected from 20 seed-trees. Mating system analysis, using mixed-mating model and paternity analysis showed that the studied population is perfectly outcrossed ( t_m = 1.002), and probably self-incompatible. However, significant deviations from random mating were detected for mating among relatives ( t_m − t_s = 0.096, P < 0.05) and correlated matings ( r_p = 0.289, P < 0.05), indicating inbreeding in the population and that part of offspring are full-sibs (28.9%). Inbreeding was reflected in the positive and significant fixation index observed in adult trees ( F = 0.137, P < 0.05), although no significant inbreeding was detected in offspring ( F = 0.074, P > 0.05). The effective number of pollen donors mating with each seed-tree was determined to be low ( N_ep ≈ 4). The average of pollen flow distance was measured inside of the plot by both paternity (827 ± 429 m) and TwoGener analysis (115–363 m). However, this underestimated pollen dispersal distance, since the detected rate of pollen immigration inside of the plot was high (55%). The observed long-pollen dispersal distance is probably related to pollination by bats and the low density of reproductive trees in the site.     

Mercury distribution in sediment profiles from lakes of the high pantanal,Mato Grosso State,Brazil

Sediment cores from lakes located in the Pantanal Swamp, Central Brazil were analysed for the distribution of mercury released by the local gold mining. Atmospheric transport is the only pathway of mercury contamination of these remote lakes. Mercury concentrations were higher at the surface of sediments (62 to 80 ug.kg^–1) decreasing to values of 20 to 30 ug.kg^–1 in deeper layers. Mercury deposition rate was estimated as 90 to 120 ug Hg.m^–2yr^–1 Although mercury concentrations were much lower than in industrialized areas, mercury deposition rate for these Pantanal lakes is of the same order of magnitude of deposition rates measured in lakes in industrialized areas     

The Role of Reactive Oxygen Species in Anopheles aquasalis Response to Plasmodium vivax Infection

Malaria affects millions of people worldwide and hundreds of thousands of people each year in Brazil. The mosquito Anopheles aquasalis is an important vector of Plasmodium vivax, the main human malaria parasite in the Americas. Reactive oxygen species (ROS) have been shown to have a role in insect innate immune responses as a potent pathogen-killing agent. We investigated the mechanisms of free radicals modulation after A. aquasalis infection with P. vivax. ROS metabolism was evaluated in the vector by studying expression and activity of three key detoxification enzymes, one catalase and two superoxide dismutases (SOD3A and SOD3B). Also, the involvement of free radicals in the mosquito immunity was measured by silencing the catalase gene followed by infection of A. aquasalis with P. vivax. Catalase, SOD3A and SOD3B expression in whole A. aquasalis were at the same levels of controls at 24 h and upregulated 36 h after ingestion of blood containing P. vivax. However, in the insect isolated midgut, the mRNA for these enzymes was not regulated by P. vivax infection, while catalase activity was reduced 24 h after the infectious meal. RNAi-mediated silencing of catalase reduced enzyme activity in the midgut, resulted in increased P. vivax infection and prevalence, and decreased bacterial load in the mosquito midgut. Our findings suggest that the interactions between A. aquasalis and P. vivax do not follow the model of ROS-induced parasite killing. It appears that P. vivax manipulates the mosquito detoxification system in order to allow its own development. This can be an indirect effect of fewer competitive bacteria present in the mosquito midgut caused by the increase of ROS after catalase silencing. These findings provide novel information on unique aspects of the main malaria parasite in the Americas interaction with one of its natural vectors.